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TOMOYO Linux Cross Reference
Linux/kernel/bpf/verifier.c

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  1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
  2  * Copyright (c) 2016 Facebook
  3  * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of version 2 of the GNU General Public
  7  * License as published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it will be useful, but
 10  * WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 12  * General Public License for more details.
 13  */
 14 #include <linux/kernel.h>
 15 #include <linux/types.h>
 16 #include <linux/slab.h>
 17 #include <linux/bpf.h>
 18 #include <linux/bpf_verifier.h>
 19 #include <linux/filter.h>
 20 #include <net/netlink.h>
 21 #include <linux/file.h>
 22 #include <linux/vmalloc.h>
 23 #include <linux/stringify.h>
 24 #include <linux/bsearch.h>
 25 #include <linux/sort.h>
 26 #include <linux/perf_event.h>
 27 
 28 #include "disasm.h"
 29 
 30 static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
 31 #define BPF_PROG_TYPE(_id, _name) \
 32         [_id] = & _name ## _verifier_ops,
 33 #define BPF_MAP_TYPE(_id, _ops)
 34 #include <linux/bpf_types.h>
 35 #undef BPF_PROG_TYPE
 36 #undef BPF_MAP_TYPE
 37 };
 38 
 39 /* bpf_check() is a static code analyzer that walks eBPF program
 40  * instruction by instruction and updates register/stack state.
 41  * All paths of conditional branches are analyzed until 'bpf_exit' insn.
 42  *
 43  * The first pass is depth-first-search to check that the program is a DAG.
 44  * It rejects the following programs:
 45  * - larger than BPF_MAXINSNS insns
 46  * - if loop is present (detected via back-edge)
 47  * - unreachable insns exist (shouldn't be a forest. program = one function)
 48  * - out of bounds or malformed jumps
 49  * The second pass is all possible path descent from the 1st insn.
 50  * Since it's analyzing all pathes through the program, the length of the
 51  * analysis is limited to 64k insn, which may be hit even if total number of
 52  * insn is less then 4K, but there are too many branches that change stack/regs.
 53  * Number of 'branches to be analyzed' is limited to 1k
 54  *
 55  * On entry to each instruction, each register has a type, and the instruction
 56  * changes the types of the registers depending on instruction semantics.
 57  * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
 58  * copied to R1.
 59  *
 60  * All registers are 64-bit.
 61  * R0 - return register
 62  * R1-R5 argument passing registers
 63  * R6-R9 callee saved registers
 64  * R10 - frame pointer read-only
 65  *
 66  * At the start of BPF program the register R1 contains a pointer to bpf_context
 67  * and has type PTR_TO_CTX.
 68  *
 69  * Verifier tracks arithmetic operations on pointers in case:
 70  *    BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
 71  *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
 72  * 1st insn copies R10 (which has FRAME_PTR) type into R1
 73  * and 2nd arithmetic instruction is pattern matched to recognize
 74  * that it wants to construct a pointer to some element within stack.
 75  * So after 2nd insn, the register R1 has type PTR_TO_STACK
 76  * (and -20 constant is saved for further stack bounds checking).
 77  * Meaning that this reg is a pointer to stack plus known immediate constant.
 78  *
 79  * Most of the time the registers have SCALAR_VALUE type, which
 80  * means the register has some value, but it's not a valid pointer.
 81  * (like pointer plus pointer becomes SCALAR_VALUE type)
 82  *
 83  * When verifier sees load or store instructions the type of base register
 84  * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
 85  * four pointer types recognized by check_mem_access() function.
 86  *
 87  * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
 88  * and the range of [ptr, ptr + map's value_size) is accessible.
 89  *
 90  * registers used to pass values to function calls are checked against
 91  * function argument constraints.
 92  *
 93  * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
 94  * It means that the register type passed to this function must be
 95  * PTR_TO_STACK and it will be used inside the function as
 96  * 'pointer to map element key'
 97  *
 98  * For example the argument constraints for bpf_map_lookup_elem():
 99  *   .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
100  *   .arg1_type = ARG_CONST_MAP_PTR,
101  *   .arg2_type = ARG_PTR_TO_MAP_KEY,
102  *
103  * ret_type says that this function returns 'pointer to map elem value or null'
104  * function expects 1st argument to be a const pointer to 'struct bpf_map' and
105  * 2nd argument should be a pointer to stack, which will be used inside
106  * the helper function as a pointer to map element key.
107  *
108  * On the kernel side the helper function looks like:
109  * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
110  * {
111  *    struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
112  *    void *key = (void *) (unsigned long) r2;
113  *    void *value;
114  *
115  *    here kernel can access 'key' and 'map' pointers safely, knowing that
116  *    [key, key + map->key_size) bytes are valid and were initialized on
117  *    the stack of eBPF program.
118  * }
119  *
120  * Corresponding eBPF program may look like:
121  *    BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),  // after this insn R2 type is FRAME_PTR
122  *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
123  *    BPF_LD_MAP_FD(BPF_REG_1, map_fd),      // after this insn R1 type is CONST_PTR_TO_MAP
124  *    BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
125  * here verifier looks at prototype of map_lookup_elem() and sees:
126  * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
127  * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
128  *
129  * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
130  * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
131  * and were initialized prior to this call.
132  * If it's ok, then verifier allows this BPF_CALL insn and looks at
133  * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
134  * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
135  * returns ether pointer to map value or NULL.
136  *
137  * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
138  * insn, the register holding that pointer in the true branch changes state to
139  * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
140  * branch. See check_cond_jmp_op().
141  *
142  * After the call R0 is set to return type of the function and registers R1-R5
143  * are set to NOT_INIT to indicate that they are no longer readable.
144  *
145  * The following reference types represent a potential reference to a kernel
146  * resource which, after first being allocated, must be checked and freed by
147  * the BPF program:
148  * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
149  *
150  * When the verifier sees a helper call return a reference type, it allocates a
151  * pointer id for the reference and stores it in the current function state.
152  * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
153  * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
154  * passes through a NULL-check conditional. For the branch wherein the state is
155  * changed to CONST_IMM, the verifier releases the reference.
156  *
157  * For each helper function that allocates a reference, such as
158  * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
159  * bpf_sk_release(). When a reference type passes into the release function,
160  * the verifier also releases the reference. If any unchecked or unreleased
161  * reference remains at the end of the program, the verifier rejects it.
162  */
163 
164 /* verifier_state + insn_idx are pushed to stack when branch is encountered */
165 struct bpf_verifier_stack_elem {
166         /* verifer state is 'st'
167          * before processing instruction 'insn_idx'
168          * and after processing instruction 'prev_insn_idx'
169          */
170         struct bpf_verifier_state st;
171         int insn_idx;
172         int prev_insn_idx;
173         struct bpf_verifier_stack_elem *next;
174 };
175 
176 #define BPF_COMPLEXITY_LIMIT_INSNS      131072
177 #define BPF_COMPLEXITY_LIMIT_STACK      1024
178 #define BPF_COMPLEXITY_LIMIT_STATES     64
179 
180 #define BPF_MAP_PTR_UNPRIV      1UL
181 #define BPF_MAP_PTR_POISON      ((void *)((0xeB9FUL << 1) +     \
182                                           POISON_POINTER_DELTA))
183 #define BPF_MAP_PTR(X)          ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))
184 
185 static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
186 {
187         return BPF_MAP_PTR(aux->map_state) == BPF_MAP_PTR_POISON;
188 }
189 
190 static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
191 {
192         return aux->map_state & BPF_MAP_PTR_UNPRIV;
193 }
194 
195 static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
196                               const struct bpf_map *map, bool unpriv)
197 {
198         BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV);
199         unpriv |= bpf_map_ptr_unpriv(aux);
200         aux->map_state = (unsigned long)map |
201                          (unpriv ? BPF_MAP_PTR_UNPRIV : 0UL);
202 }
203 
204 struct bpf_call_arg_meta {
205         struct bpf_map *map_ptr;
206         bool raw_mode;
207         bool pkt_access;
208         int regno;
209         int access_size;
210         s64 msize_smax_value;
211         u64 msize_umax_value;
212         int ptr_id;
213 };
214 
215 static DEFINE_MUTEX(bpf_verifier_lock);
216 
217 void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
218                        va_list args)
219 {
220         unsigned int n;
221 
222         n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
223 
224         WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
225                   "verifier log line truncated - local buffer too short\n");
226 
227         n = min(log->len_total - log->len_used - 1, n);
228         log->kbuf[n] = '\0';
229 
230         if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
231                 log->len_used += n;
232         else
233                 log->ubuf = NULL;
234 }
235 
236 /* log_level controls verbosity level of eBPF verifier.
237  * bpf_verifier_log_write() is used to dump the verification trace to the log,
238  * so the user can figure out what's wrong with the program
239  */
240 __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
241                                            const char *fmt, ...)
242 {
243         va_list args;
244 
245         if (!bpf_verifier_log_needed(&env->log))
246                 return;
247 
248         va_start(args, fmt);
249         bpf_verifier_vlog(&env->log, fmt, args);
250         va_end(args);
251 }
252 EXPORT_SYMBOL_GPL(bpf_verifier_log_write);
253 
254 __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
255 {
256         struct bpf_verifier_env *env = private_data;
257         va_list args;
258 
259         if (!bpf_verifier_log_needed(&env->log))
260                 return;
261 
262         va_start(args, fmt);
263         bpf_verifier_vlog(&env->log, fmt, args);
264         va_end(args);
265 }
266 
267 static bool type_is_pkt_pointer(enum bpf_reg_type type)
268 {
269         return type == PTR_TO_PACKET ||
270                type == PTR_TO_PACKET_META;
271 }
272 
273 static bool reg_type_may_be_null(enum bpf_reg_type type)
274 {
275         return type == PTR_TO_MAP_VALUE_OR_NULL ||
276                type == PTR_TO_SOCKET_OR_NULL;
277 }
278 
279 static bool type_is_refcounted(enum bpf_reg_type type)
280 {
281         return type == PTR_TO_SOCKET;
282 }
283 
284 static bool type_is_refcounted_or_null(enum bpf_reg_type type)
285 {
286         return type == PTR_TO_SOCKET || type == PTR_TO_SOCKET_OR_NULL;
287 }
288 
289 static bool reg_is_refcounted(const struct bpf_reg_state *reg)
290 {
291         return type_is_refcounted(reg->type);
292 }
293 
294 static bool reg_is_refcounted_or_null(const struct bpf_reg_state *reg)
295 {
296         return type_is_refcounted_or_null(reg->type);
297 }
298 
299 static bool arg_type_is_refcounted(enum bpf_arg_type type)
300 {
301         return type == ARG_PTR_TO_SOCKET;
302 }
303 
304 /* Determine whether the function releases some resources allocated by another
305  * function call. The first reference type argument will be assumed to be
306  * released by release_reference().
307  */
308 static bool is_release_function(enum bpf_func_id func_id)
309 {
310         return func_id == BPF_FUNC_sk_release;
311 }
312 
313 /* string representation of 'enum bpf_reg_type' */
314 static const char * const reg_type_str[] = {
315         [NOT_INIT]              = "?",
316         [SCALAR_VALUE]          = "inv",
317         [PTR_TO_CTX]            = "ctx",
318         [CONST_PTR_TO_MAP]      = "map_ptr",
319         [PTR_TO_MAP_VALUE]      = "map_value",
320         [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
321         [PTR_TO_STACK]          = "fp",
322         [PTR_TO_PACKET]         = "pkt",
323         [PTR_TO_PACKET_META]    = "pkt_meta",
324         [PTR_TO_PACKET_END]     = "pkt_end",
325         [PTR_TO_FLOW_KEYS]      = "flow_keys",
326         [PTR_TO_SOCKET]         = "sock",
327         [PTR_TO_SOCKET_OR_NULL] = "sock_or_null",
328 };
329 
330 static char slot_type_char[] = {
331         [STACK_INVALID] = '?',
332         [STACK_SPILL]   = 'r',
333         [STACK_MISC]    = 'm',
334         [STACK_ZERO]    = '',
335 };
336 
337 static void print_liveness(struct bpf_verifier_env *env,
338                            enum bpf_reg_liveness live)
339 {
340         if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN))
341             verbose(env, "_");
342         if (live & REG_LIVE_READ)
343                 verbose(env, "r");
344         if (live & REG_LIVE_WRITTEN)
345                 verbose(env, "w");
346 }
347 
348 static struct bpf_func_state *func(struct bpf_verifier_env *env,
349                                    const struct bpf_reg_state *reg)
350 {
351         struct bpf_verifier_state *cur = env->cur_state;
352 
353         return cur->frame[reg->frameno];
354 }
355 
356 static void print_verifier_state(struct bpf_verifier_env *env,
357                                  const struct bpf_func_state *state)
358 {
359         const struct bpf_reg_state *reg;
360         enum bpf_reg_type t;
361         int i;
362 
363         if (state->frameno)
364                 verbose(env, " frame%d:", state->frameno);
365         for (i = 0; i < MAX_BPF_REG; i++) {
366                 reg = &state->regs[i];
367                 t = reg->type;
368                 if (t == NOT_INIT)
369                         continue;
370                 verbose(env, " R%d", i);
371                 print_liveness(env, reg->live);
372                 verbose(env, "=%s", reg_type_str[t]);
373                 if ((t == SCALAR_VALUE || t == PTR_TO_STACK) &&
374                     tnum_is_const(reg->var_off)) {
375                         /* reg->off should be 0 for SCALAR_VALUE */
376                         verbose(env, "%lld", reg->var_off.value + reg->off);
377                         if (t == PTR_TO_STACK)
378                                 verbose(env, ",call_%d", func(env, reg)->callsite);
379                 } else {
380                         verbose(env, "(id=%d", reg->id);
381                         if (t != SCALAR_VALUE)
382                                 verbose(env, ",off=%d", reg->off);
383                         if (type_is_pkt_pointer(t))
384                                 verbose(env, ",r=%d", reg->range);
385                         else if (t == CONST_PTR_TO_MAP ||
386                                  t == PTR_TO_MAP_VALUE ||
387                                  t == PTR_TO_MAP_VALUE_OR_NULL)
388                                 verbose(env, ",ks=%d,vs=%d",
389                                         reg->map_ptr->key_size,
390                                         reg->map_ptr->value_size);
391                         if (tnum_is_const(reg->var_off)) {
392                                 /* Typically an immediate SCALAR_VALUE, but
393                                  * could be a pointer whose offset is too big
394                                  * for reg->off
395                                  */
396                                 verbose(env, ",imm=%llx", reg->var_off.value);
397                         } else {
398                                 if (reg->smin_value != reg->umin_value &&
399                                     reg->smin_value != S64_MIN)
400                                         verbose(env, ",smin_value=%lld",
401                                                 (long long)reg->smin_value);
402                                 if (reg->smax_value != reg->umax_value &&
403                                     reg->smax_value != S64_MAX)
404                                         verbose(env, ",smax_value=%lld",
405                                                 (long long)reg->smax_value);
406                                 if (reg->umin_value != 0)
407                                         verbose(env, ",umin_value=%llu",
408                                                 (unsigned long long)reg->umin_value);
409                                 if (reg->umax_value != U64_MAX)
410                                         verbose(env, ",umax_value=%llu",
411                                                 (unsigned long long)reg->umax_value);
412                                 if (!tnum_is_unknown(reg->var_off)) {
413                                         char tn_buf[48];
414 
415                                         tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
416                                         verbose(env, ",var_off=%s", tn_buf);
417                                 }
418                         }
419                         verbose(env, ")");
420                 }
421         }
422         for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
423                 char types_buf[BPF_REG_SIZE + 1];
424                 bool valid = false;
425                 int j;
426 
427                 for (j = 0; j < BPF_REG_SIZE; j++) {
428                         if (state->stack[i].slot_type[j] != STACK_INVALID)
429                                 valid = true;
430                         types_buf[j] = slot_type_char[
431                                         state->stack[i].slot_type[j]];
432                 }
433                 types_buf[BPF_REG_SIZE] = 0;
434                 if (!valid)
435                         continue;
436                 verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE);
437                 print_liveness(env, state->stack[i].spilled_ptr.live);
438                 if (state->stack[i].slot_type[0] == STACK_SPILL)
439                         verbose(env, "=%s",
440                                 reg_type_str[state->stack[i].spilled_ptr.type]);
441                 else
442                         verbose(env, "=%s", types_buf);
443         }
444         if (state->acquired_refs && state->refs[0].id) {
445                 verbose(env, " refs=%d", state->refs[0].id);
446                 for (i = 1; i < state->acquired_refs; i++)
447                         if (state->refs[i].id)
448                                 verbose(env, ",%d", state->refs[i].id);
449         }
450         verbose(env, "\n");
451 }
452 
453 #define COPY_STATE_FN(NAME, COUNT, FIELD, SIZE)                         \
454 static int copy_##NAME##_state(struct bpf_func_state *dst,              \
455                                const struct bpf_func_state *src)        \
456 {                                                                       \
457         if (!src->FIELD)                                                \
458                 return 0;                                               \
459         if (WARN_ON_ONCE(dst->COUNT < src->COUNT)) {                    \
460                 /* internal bug, make state invalid to reject the program */ \
461                 memset(dst, 0, sizeof(*dst));                           \
462                 return -EFAULT;                                         \
463         }                                                               \
464         memcpy(dst->FIELD, src->FIELD,                                  \
465                sizeof(*src->FIELD) * (src->COUNT / SIZE));              \
466         return 0;                                                       \
467 }
468 /* copy_reference_state() */
469 COPY_STATE_FN(reference, acquired_refs, refs, 1)
470 /* copy_stack_state() */
471 COPY_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
472 #undef COPY_STATE_FN
473 
474 #define REALLOC_STATE_FN(NAME, COUNT, FIELD, SIZE)                      \
475 static int realloc_##NAME##_state(struct bpf_func_state *state, int size, \
476                                   bool copy_old)                        \
477 {                                                                       \
478         u32 old_size = state->COUNT;                                    \
479         struct bpf_##NAME##_state *new_##FIELD;                         \
480         int slot = size / SIZE;                                         \
481                                                                         \
482         if (size <= old_size || !size) {                                \
483                 if (copy_old)                                           \
484                         return 0;                                       \
485                 state->COUNT = slot * SIZE;                             \
486                 if (!size && old_size) {                                \
487                         kfree(state->FIELD);                            \
488                         state->FIELD = NULL;                            \
489                 }                                                       \
490                 return 0;                                               \
491         }                                                               \
492         new_##FIELD = kmalloc_array(slot, sizeof(struct bpf_##NAME##_state), \
493                                     GFP_KERNEL);                        \
494         if (!new_##FIELD)                                               \
495                 return -ENOMEM;                                         \
496         if (copy_old) {                                                 \
497                 if (state->FIELD)                                       \
498                         memcpy(new_##FIELD, state->FIELD,               \
499                                sizeof(*new_##FIELD) * (old_size / SIZE)); \
500                 memset(new_##FIELD + old_size / SIZE, 0,                \
501                        sizeof(*new_##FIELD) * (size - old_size) / SIZE); \
502         }                                                               \
503         state->COUNT = slot * SIZE;                                     \
504         kfree(state->FIELD);                                            \
505         state->FIELD = new_##FIELD;                                     \
506         return 0;                                                       \
507 }
508 /* realloc_reference_state() */
509 REALLOC_STATE_FN(reference, acquired_refs, refs, 1)
510 /* realloc_stack_state() */
511 REALLOC_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
512 #undef REALLOC_STATE_FN
513 
514 /* do_check() starts with zero-sized stack in struct bpf_verifier_state to
515  * make it consume minimal amount of memory. check_stack_write() access from
516  * the program calls into realloc_func_state() to grow the stack size.
517  * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
518  * which realloc_stack_state() copies over. It points to previous
519  * bpf_verifier_state which is never reallocated.
520  */
521 static int realloc_func_state(struct bpf_func_state *state, int stack_size,
522                               int refs_size, bool copy_old)
523 {
524         int err = realloc_reference_state(state, refs_size, copy_old);
525         if (err)
526                 return err;
527         return realloc_stack_state(state, stack_size, copy_old);
528 }
529 
530 /* Acquire a pointer id from the env and update the state->refs to include
531  * this new pointer reference.
532  * On success, returns a valid pointer id to associate with the register
533  * On failure, returns a negative errno.
534  */
535 static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
536 {
537         struct bpf_func_state *state = cur_func(env);
538         int new_ofs = state->acquired_refs;
539         int id, err;
540 
541         err = realloc_reference_state(state, state->acquired_refs + 1, true);
542         if (err)
543                 return err;
544         id = ++env->id_gen;
545         state->refs[new_ofs].id = id;
546         state->refs[new_ofs].insn_idx = insn_idx;
547 
548         return id;
549 }
550 
551 /* release function corresponding to acquire_reference_state(). Idempotent. */
552 static int __release_reference_state(struct bpf_func_state *state, int ptr_id)
553 {
554         int i, last_idx;
555 
556         if (!ptr_id)
557                 return -EFAULT;
558 
559         last_idx = state->acquired_refs - 1;
560         for (i = 0; i < state->acquired_refs; i++) {
561                 if (state->refs[i].id == ptr_id) {
562                         if (last_idx && i != last_idx)
563                                 memcpy(&state->refs[i], &state->refs[last_idx],
564                                        sizeof(*state->refs));
565                         memset(&state->refs[last_idx], 0, sizeof(*state->refs));
566                         state->acquired_refs--;
567                         return 0;
568                 }
569         }
570         return -EFAULT;
571 }
572 
573 /* variation on the above for cases where we expect that there must be an
574  * outstanding reference for the specified ptr_id.
575  */
576 static int release_reference_state(struct bpf_verifier_env *env, int ptr_id)
577 {
578         struct bpf_func_state *state = cur_func(env);
579         int err;
580 
581         err = __release_reference_state(state, ptr_id);
582         if (WARN_ON_ONCE(err != 0))
583                 verbose(env, "verifier internal error: can't release reference\n");
584         return err;
585 }
586 
587 static int transfer_reference_state(struct bpf_func_state *dst,
588                                     struct bpf_func_state *src)
589 {
590         int err = realloc_reference_state(dst, src->acquired_refs, false);
591         if (err)
592                 return err;
593         err = copy_reference_state(dst, src);
594         if (err)
595                 return err;
596         return 0;
597 }
598 
599 static void free_func_state(struct bpf_func_state *state)
600 {
601         if (!state)
602                 return;
603         kfree(state->refs);
604         kfree(state->stack);
605         kfree(state);
606 }
607 
608 static void free_verifier_state(struct bpf_verifier_state *state,
609                                 bool free_self)
610 {
611         int i;
612 
613         for (i = 0; i <= state->curframe; i++) {
614                 free_func_state(state->frame[i]);
615                 state->frame[i] = NULL;
616         }
617         if (free_self)
618                 kfree(state);
619 }
620 
621 /* copy verifier state from src to dst growing dst stack space
622  * when necessary to accommodate larger src stack
623  */
624 static int copy_func_state(struct bpf_func_state *dst,
625                            const struct bpf_func_state *src)
626 {
627         int err;
628 
629         err = realloc_func_state(dst, src->allocated_stack, src->acquired_refs,
630                                  false);
631         if (err)
632                 return err;
633         memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
634         err = copy_reference_state(dst, src);
635         if (err)
636                 return err;
637         return copy_stack_state(dst, src);
638 }
639 
640 static int copy_verifier_state(struct bpf_verifier_state *dst_state,
641                                const struct bpf_verifier_state *src)
642 {
643         struct bpf_func_state *dst;
644         int i, err;
645 
646         /* if dst has more stack frames then src frame, free them */
647         for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
648                 free_func_state(dst_state->frame[i]);
649                 dst_state->frame[i] = NULL;
650         }
651         dst_state->curframe = src->curframe;
652         for (i = 0; i <= src->curframe; i++) {
653                 dst = dst_state->frame[i];
654                 if (!dst) {
655                         dst = kzalloc(sizeof(*dst), GFP_KERNEL);
656                         if (!dst)
657                                 return -ENOMEM;
658                         dst_state->frame[i] = dst;
659                 }
660                 err = copy_func_state(dst, src->frame[i]);
661                 if (err)
662                         return err;
663         }
664         return 0;
665 }
666 
667 static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
668                      int *insn_idx)
669 {
670         struct bpf_verifier_state *cur = env->cur_state;
671         struct bpf_verifier_stack_elem *elem, *head = env->head;
672         int err;
673 
674         if (env->head == NULL)
675                 return -ENOENT;
676 
677         if (cur) {
678                 err = copy_verifier_state(cur, &head->st);
679                 if (err)
680                         return err;
681         }
682         if (insn_idx)
683                 *insn_idx = head->insn_idx;
684         if (prev_insn_idx)
685                 *prev_insn_idx = head->prev_insn_idx;
686         elem = head->next;
687         free_verifier_state(&head->st, false);
688         kfree(head);
689         env->head = elem;
690         env->stack_size--;
691         return 0;
692 }
693 
694 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
695                                              int insn_idx, int prev_insn_idx)
696 {
697         struct bpf_verifier_state *cur = env->cur_state;
698         struct bpf_verifier_stack_elem *elem;
699         int err;
700 
701         elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
702         if (!elem)
703                 goto err;
704 
705         elem->insn_idx = insn_idx;
706         elem->prev_insn_idx = prev_insn_idx;
707         elem->next = env->head;
708         env->head = elem;
709         env->stack_size++;
710         err = copy_verifier_state(&elem->st, cur);
711         if (err)
712                 goto err;
713         if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
714                 verbose(env, "BPF program is too complex\n");
715                 goto err;
716         }
717         return &elem->st;
718 err:
719         free_verifier_state(env->cur_state, true);
720         env->cur_state = NULL;
721         /* pop all elements and return */
722         while (!pop_stack(env, NULL, NULL));
723         return NULL;
724 }
725 
726 #define CALLER_SAVED_REGS 6
727 static const int caller_saved[CALLER_SAVED_REGS] = {
728         BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
729 };
730 
731 static void __mark_reg_not_init(struct bpf_reg_state *reg);
732 
733 /* Mark the unknown part of a register (variable offset or scalar value) as
734  * known to have the value @imm.
735  */
736 static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
737 {
738         /* Clear id, off, and union(map_ptr, range) */
739         memset(((u8 *)reg) + sizeof(reg->type), 0,
740                offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
741         reg->var_off = tnum_const(imm);
742         reg->smin_value = (s64)imm;
743         reg->smax_value = (s64)imm;
744         reg->umin_value = imm;
745         reg->umax_value = imm;
746 }
747 
748 /* Mark the 'variable offset' part of a register as zero.  This should be
749  * used only on registers holding a pointer type.
750  */
751 static void __mark_reg_known_zero(struct bpf_reg_state *reg)
752 {
753         __mark_reg_known(reg, 0);
754 }
755 
756 static void __mark_reg_const_zero(struct bpf_reg_state *reg)
757 {
758         __mark_reg_known(reg, 0);
759         reg->type = SCALAR_VALUE;
760 }
761 
762 static void mark_reg_known_zero(struct bpf_verifier_env *env,
763                                 struct bpf_reg_state *regs, u32 regno)
764 {
765         if (WARN_ON(regno >= MAX_BPF_REG)) {
766                 verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
767                 /* Something bad happened, let's kill all regs */
768                 for (regno = 0; regno < MAX_BPF_REG; regno++)
769                         __mark_reg_not_init(regs + regno);
770                 return;
771         }
772         __mark_reg_known_zero(regs + regno);
773 }
774 
775 static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
776 {
777         return type_is_pkt_pointer(reg->type);
778 }
779 
780 static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
781 {
782         return reg_is_pkt_pointer(reg) ||
783                reg->type == PTR_TO_PACKET_END;
784 }
785 
786 /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
787 static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
788                                     enum bpf_reg_type which)
789 {
790         /* The register can already have a range from prior markings.
791          * This is fine as long as it hasn't been advanced from its
792          * origin.
793          */
794         return reg->type == which &&
795                reg->id == 0 &&
796                reg->off == 0 &&
797                tnum_equals_const(reg->var_off, 0);
798 }
799 
800 /* Attempts to improve min/max values based on var_off information */
801 static void __update_reg_bounds(struct bpf_reg_state *reg)
802 {
803         /* min signed is max(sign bit) | min(other bits) */
804         reg->smin_value = max_t(s64, reg->smin_value,
805                                 reg->var_off.value | (reg->var_off.mask & S64_MIN));
806         /* max signed is min(sign bit) | max(other bits) */
807         reg->smax_value = min_t(s64, reg->smax_value,
808                                 reg->var_off.value | (reg->var_off.mask & S64_MAX));
809         reg->umin_value = max(reg->umin_value, reg->var_off.value);
810         reg->umax_value = min(reg->umax_value,
811                               reg->var_off.value | reg->var_off.mask);
812 }
813 
814 /* Uses signed min/max values to inform unsigned, and vice-versa */
815 static void __reg_deduce_bounds(struct bpf_reg_state *reg)
816 {
817         /* Learn sign from signed bounds.
818          * If we cannot cross the sign boundary, then signed and unsigned bounds
819          * are the same, so combine.  This works even in the negative case, e.g.
820          * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
821          */
822         if (reg->smin_value >= 0 || reg->smax_value < 0) {
823                 reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
824                                                           reg->umin_value);
825                 reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
826                                                           reg->umax_value);
827                 return;
828         }
829         /* Learn sign from unsigned bounds.  Signed bounds cross the sign
830          * boundary, so we must be careful.
831          */
832         if ((s64)reg->umax_value >= 0) {
833                 /* Positive.  We can't learn anything from the smin, but smax
834                  * is positive, hence safe.
835                  */
836                 reg->smin_value = reg->umin_value;
837                 reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
838                                                           reg->umax_value);
839         } else if ((s64)reg->umin_value < 0) {
840                 /* Negative.  We can't learn anything from the smax, but smin
841                  * is negative, hence safe.
842                  */
843                 reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
844                                                           reg->umin_value);
845                 reg->smax_value = reg->umax_value;
846         }
847 }
848 
849 /* Attempts to improve var_off based on unsigned min/max information */
850 static void __reg_bound_offset(struct bpf_reg_state *reg)
851 {
852         reg->var_off = tnum_intersect(reg->var_off,
853                                       tnum_range(reg->umin_value,
854                                                  reg->umax_value));
855 }
856 
857 /* Reset the min/max bounds of a register */
858 static void __mark_reg_unbounded(struct bpf_reg_state *reg)
859 {
860         reg->smin_value = S64_MIN;
861         reg->smax_value = S64_MAX;
862         reg->umin_value = 0;
863         reg->umax_value = U64_MAX;
864 }
865 
866 /* Mark a register as having a completely unknown (scalar) value. */
867 static void __mark_reg_unknown(struct bpf_reg_state *reg)
868 {
869         /*
870          * Clear type, id, off, and union(map_ptr, range) and
871          * padding between 'type' and union
872          */
873         memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
874         reg->type = SCALAR_VALUE;
875         reg->var_off = tnum_unknown;
876         reg->frameno = 0;
877         __mark_reg_unbounded(reg);
878 }
879 
880 static void mark_reg_unknown(struct bpf_verifier_env *env,
881                              struct bpf_reg_state *regs, u32 regno)
882 {
883         if (WARN_ON(regno >= MAX_BPF_REG)) {
884                 verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
885                 /* Something bad happened, let's kill all regs except FP */
886                 for (regno = 0; regno < BPF_REG_FP; regno++)
887                         __mark_reg_not_init(regs + regno);
888                 return;
889         }
890         __mark_reg_unknown(regs + regno);
891 }
892 
893 static void __mark_reg_not_init(struct bpf_reg_state *reg)
894 {
895         __mark_reg_unknown(reg);
896         reg->type = NOT_INIT;
897 }
898 
899 static void mark_reg_not_init(struct bpf_verifier_env *env,
900                               struct bpf_reg_state *regs, u32 regno)
901 {
902         if (WARN_ON(regno >= MAX_BPF_REG)) {
903                 verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
904                 /* Something bad happened, let's kill all regs except FP */
905                 for (regno = 0; regno < BPF_REG_FP; regno++)
906                         __mark_reg_not_init(regs + regno);
907                 return;
908         }
909         __mark_reg_not_init(regs + regno);
910 }
911 
912 static void init_reg_state(struct bpf_verifier_env *env,
913                            struct bpf_func_state *state)
914 {
915         struct bpf_reg_state *regs = state->regs;
916         int i;
917 
918         for (i = 0; i < MAX_BPF_REG; i++) {
919                 mark_reg_not_init(env, regs, i);
920                 regs[i].live = REG_LIVE_NONE;
921                 regs[i].parent = NULL;
922         }
923 
924         /* frame pointer */
925         regs[BPF_REG_FP].type = PTR_TO_STACK;
926         mark_reg_known_zero(env, regs, BPF_REG_FP);
927         regs[BPF_REG_FP].frameno = state->frameno;
928 
929         /* 1st arg to a function */
930         regs[BPF_REG_1].type = PTR_TO_CTX;
931         mark_reg_known_zero(env, regs, BPF_REG_1);
932 }
933 
934 #define BPF_MAIN_FUNC (-1)
935 static void init_func_state(struct bpf_verifier_env *env,
936                             struct bpf_func_state *state,
937                             int callsite, int frameno, int subprogno)
938 {
939         state->callsite = callsite;
940         state->frameno = frameno;
941         state->subprogno = subprogno;
942         init_reg_state(env, state);
943 }
944 
945 enum reg_arg_type {
946         SRC_OP,         /* register is used as source operand */
947         DST_OP,         /* register is used as destination operand */
948         DST_OP_NO_MARK  /* same as above, check only, don't mark */
949 };
950 
951 static int cmp_subprogs(const void *a, const void *b)
952 {
953         return ((struct bpf_subprog_info *)a)->start -
954                ((struct bpf_subprog_info *)b)->start;
955 }
956 
957 static int find_subprog(struct bpf_verifier_env *env, int off)
958 {
959         struct bpf_subprog_info *p;
960 
961         p = bsearch(&off, env->subprog_info, env->subprog_cnt,
962                     sizeof(env->subprog_info[0]), cmp_subprogs);
963         if (!p)
964                 return -ENOENT;
965         return p - env->subprog_info;
966 
967 }
968 
969 static int add_subprog(struct bpf_verifier_env *env, int off)
970 {
971         int insn_cnt = env->prog->len;
972         int ret;
973 
974         if (off >= insn_cnt || off < 0) {
975                 verbose(env, "call to invalid destination\n");
976                 return -EINVAL;
977         }
978         ret = find_subprog(env, off);
979         if (ret >= 0)
980                 return 0;
981         if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
982                 verbose(env, "too many subprograms\n");
983                 return -E2BIG;
984         }
985         env->subprog_info[env->subprog_cnt++].start = off;
986         sort(env->subprog_info, env->subprog_cnt,
987              sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
988         return 0;
989 }
990 
991 static int check_subprogs(struct bpf_verifier_env *env)
992 {
993         int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;
994         struct bpf_subprog_info *subprog = env->subprog_info;
995         struct bpf_insn *insn = env->prog->insnsi;
996         int insn_cnt = env->prog->len;
997 
998         /* Add entry function. */
999         ret = add_subprog(env, 0);
1000         if (ret < 0)
1001                 return ret;
1002 
1003         /* determine subprog starts. The end is one before the next starts */
1004         for (i = 0; i < insn_cnt; i++) {
1005                 if (insn[i].code != (BPF_JMP | BPF_CALL))
1006                         continue;
1007                 if (insn[i].src_reg != BPF_PSEUDO_CALL)
1008                         continue;
1009                 if (!env->allow_ptr_leaks) {
1010                         verbose(env, "function calls to other bpf functions are allowed for root only\n");
1011                         return -EPERM;
1012                 }
1013                 ret = add_subprog(env, i + insn[i].imm + 1);
1014                 if (ret < 0)
1015                         return ret;
1016         }
1017 
1018         /* Add a fake 'exit' subprog which could simplify subprog iteration
1019          * logic. 'subprog_cnt' should not be increased.
1020          */
1021         subprog[env->subprog_cnt].start = insn_cnt;
1022 
1023         if (env->log.level > 1)
1024                 for (i = 0; i < env->subprog_cnt; i++)
1025                         verbose(env, "func#%d @%d\n", i, subprog[i].start);
1026 
1027         /* now check that all jumps are within the same subprog */
1028         subprog_start = subprog[cur_subprog].start;
1029         subprog_end = subprog[cur_subprog + 1].start;
1030         for (i = 0; i < insn_cnt; i++) {
1031                 u8 code = insn[i].code;
1032 
1033                 if (BPF_CLASS(code) != BPF_JMP)
1034                         goto next;
1035                 if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
1036                         goto next;
1037                 off = i + insn[i].off + 1;
1038                 if (off < subprog_start || off >= subprog_end) {
1039                         verbose(env, "jump out of range from insn %d to %d\n", i, off);
1040                         return -EINVAL;
1041                 }
1042 next:
1043                 if (i == subprog_end - 1) {
1044                         /* to avoid fall-through from one subprog into another
1045                          * the last insn of the subprog should be either exit
1046                          * or unconditional jump back
1047                          */
1048                         if (code != (BPF_JMP | BPF_EXIT) &&
1049                             code != (BPF_JMP | BPF_JA)) {
1050                                 verbose(env, "last insn is not an exit or jmp\n");
1051                                 return -EINVAL;
1052                         }
1053                         subprog_start = subprog_end;
1054                         cur_subprog++;
1055                         if (cur_subprog < env->subprog_cnt)
1056                                 subprog_end = subprog[cur_subprog + 1].start;
1057                 }
1058         }
1059         return 0;
1060 }
1061 
1062 /* Parentage chain of this register (or stack slot) should take care of all
1063  * issues like callee-saved registers, stack slot allocation time, etc.
1064  */
1065 static int mark_reg_read(struct bpf_verifier_env *env,
1066                          const struct bpf_reg_state *state,
1067                          struct bpf_reg_state *parent)
1068 {
1069         bool writes = parent == state->parent; /* Observe write marks */
1070 
1071         while (parent) {
1072                 /* if read wasn't screened by an earlier write ... */
1073                 if (writes && state->live & REG_LIVE_WRITTEN)
1074                         break;
1075                 /* ... then we depend on parent's value */
1076                 parent->live |= REG_LIVE_READ;
1077                 state = parent;
1078                 parent = state->parent;
1079                 writes = true;
1080         }
1081         return 0;
1082 }
1083 
1084 static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
1085                          enum reg_arg_type t)
1086 {
1087         struct bpf_verifier_state *vstate = env->cur_state;
1088         struct bpf_func_state *state = vstate->frame[vstate->curframe];
1089         struct bpf_reg_state *regs = state->regs;
1090 
1091         if (regno >= MAX_BPF_REG) {
1092                 verbose(env, "R%d is invalid\n", regno);
1093                 return -EINVAL;
1094         }
1095 
1096         if (t == SRC_OP) {
1097                 /* check whether register used as source operand can be read */
1098                 if (regs[regno].type == NOT_INIT) {
1099                         verbose(env, "R%d !read_ok\n", regno);
1100                         return -EACCES;
1101                 }
1102                 /* We don't need to worry about FP liveness because it's read-only */
1103                 if (regno != BPF_REG_FP)
1104                         return mark_reg_read(env, &regs[regno],
1105                                              regs[regno].parent);
1106         } else {
1107                 /* check whether register used as dest operand can be written to */
1108                 if (regno == BPF_REG_FP) {
1109                         verbose(env, "frame pointer is read only\n");
1110                         return -EACCES;
1111                 }
1112                 regs[regno].live |= REG_LIVE_WRITTEN;
1113                 if (t == DST_OP)
1114                         mark_reg_unknown(env, regs, regno);
1115         }
1116         return 0;
1117 }
1118 
1119 static bool is_spillable_regtype(enum bpf_reg_type type)
1120 {
1121         switch (type) {
1122         case PTR_TO_MAP_VALUE:
1123         case PTR_TO_MAP_VALUE_OR_NULL:
1124         case PTR_TO_STACK:
1125         case PTR_TO_CTX:
1126         case PTR_TO_PACKET:
1127         case PTR_TO_PACKET_META:
1128         case PTR_TO_PACKET_END:
1129         case PTR_TO_FLOW_KEYS:
1130         case CONST_PTR_TO_MAP:
1131         case PTR_TO_SOCKET:
1132         case PTR_TO_SOCKET_OR_NULL:
1133                 return true;
1134         default:
1135                 return false;
1136         }
1137 }
1138 
1139 /* Does this register contain a constant zero? */
1140 static bool register_is_null(struct bpf_reg_state *reg)
1141 {
1142         return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
1143 }
1144 
1145 /* check_stack_read/write functions track spill/fill of registers,
1146  * stack boundary and alignment are checked in check_mem_access()
1147  */
1148 static int check_stack_write(struct bpf_verifier_env *env,
1149                              struct bpf_func_state *state, /* func where register points to */
1150                              int off, int size, int value_regno, int insn_idx)
1151 {
1152         struct bpf_func_state *cur; /* state of the current function */
1153         int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
1154         enum bpf_reg_type type;
1155 
1156         err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE),
1157                                  state->acquired_refs, true);
1158         if (err)
1159                 return err;
1160         /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
1161          * so it's aligned access and [off, off + size) are within stack limits
1162          */
1163         if (!env->allow_ptr_leaks &&
1164             state->stack[spi].slot_type[0] == STACK_SPILL &&
1165             size != BPF_REG_SIZE) {
1166                 verbose(env, "attempt to corrupt spilled pointer on stack\n");
1167                 return -EACCES;
1168         }
1169 
1170         cur = env->cur_state->frame[env->cur_state->curframe];
1171         if (value_regno >= 0 &&
1172             is_spillable_regtype((type = cur->regs[value_regno].type))) {
1173 
1174                 /* register containing pointer is being spilled into stack */
1175                 if (size != BPF_REG_SIZE) {
1176                         verbose(env, "invalid size of register spill\n");
1177                         return -EACCES;
1178                 }
1179 
1180                 if (state != cur && type == PTR_TO_STACK) {
1181                         verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
1182                         return -EINVAL;
1183                 }
1184 
1185                 /* save register state */
1186                 state->stack[spi].spilled_ptr = cur->regs[value_regno];
1187                 state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
1188 
1189                 for (i = 0; i < BPF_REG_SIZE; i++) {
1190                         if (state->stack[spi].slot_type[i] == STACK_MISC &&
1191                             !env->allow_ptr_leaks) {
1192                                 int *poff = &env->insn_aux_data[insn_idx].sanitize_stack_off;
1193                                 int soff = (-spi - 1) * BPF_REG_SIZE;
1194 
1195                                 /* detected reuse of integer stack slot with a pointer
1196                                  * which means either llvm is reusing stack slot or
1197                                  * an attacker is trying to exploit CVE-2018-3639
1198                                  * (speculative store bypass)
1199                                  * Have to sanitize that slot with preemptive
1200                                  * store of zero.
1201                                  */
1202                                 if (*poff && *poff != soff) {
1203                                         /* disallow programs where single insn stores
1204                                          * into two different stack slots, since verifier
1205                                          * cannot sanitize them
1206                                          */
1207                                         verbose(env,
1208                                                 "insn %d cannot access two stack slots fp%d and fp%d",
1209                                                 insn_idx, *poff, soff);
1210                                         return -EINVAL;
1211                                 }
1212                                 *poff = soff;
1213                         }
1214                         state->stack[spi].slot_type[i] = STACK_SPILL;
1215                 }
1216         } else {
1217                 u8 type = STACK_MISC;
1218 
1219                 /* regular write of data into stack destroys any spilled ptr */
1220                 state->stack[spi].spilled_ptr.type = NOT_INIT;
1221 
1222                 /* only mark the slot as written if all 8 bytes were written
1223                  * otherwise read propagation may incorrectly stop too soon
1224                  * when stack slots are partially written.
1225                  * This heuristic means that read propagation will be
1226                  * conservative, since it will add reg_live_read marks
1227                  * to stack slots all the way to first state when programs
1228                  * writes+reads less than 8 bytes
1229                  */
1230                 if (size == BPF_REG_SIZE)
1231                         state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
1232 
1233                 /* when we zero initialize stack slots mark them as such */
1234                 if (value_regno >= 0 &&
1235                     register_is_null(&cur->regs[value_regno]))
1236                         type = STACK_ZERO;
1237 
1238                 for (i = 0; i < size; i++)
1239                         state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] =
1240                                 type;
1241         }
1242         return 0;
1243 }
1244 
1245 static int check_stack_read(struct bpf_verifier_env *env,
1246                             struct bpf_func_state *reg_state /* func where register points to */,
1247                             int off, int size, int value_regno)
1248 {
1249         struct bpf_verifier_state *vstate = env->cur_state;
1250         struct bpf_func_state *state = vstate->frame[vstate->curframe];
1251         int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
1252         u8 *stype;
1253 
1254         if (reg_state->allocated_stack <= slot) {
1255                 verbose(env, "invalid read from stack off %d+0 size %d\n",
1256                         off, size);
1257                 return -EACCES;
1258         }
1259         stype = reg_state->stack[spi].slot_type;
1260 
1261         if (stype[0] == STACK_SPILL) {
1262                 if (size != BPF_REG_SIZE) {
1263                         verbose(env, "invalid size of register spill\n");
1264                         return -EACCES;
1265                 }
1266                 for (i = 1; i < BPF_REG_SIZE; i++) {
1267                         if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
1268                                 verbose(env, "corrupted spill memory\n");
1269                                 return -EACCES;
1270                         }
1271                 }
1272 
1273                 if (value_regno >= 0) {
1274                         /* restore register state from stack */
1275                         state->regs[value_regno] = reg_state->stack[spi].spilled_ptr;
1276                         /* mark reg as written since spilled pointer state likely
1277                          * has its liveness marks cleared by is_state_visited()
1278                          * which resets stack/reg liveness for state transitions
1279                          */
1280                         state->regs[value_regno].live |= REG_LIVE_WRITTEN;
1281                 }
1282                 mark_reg_read(env, &reg_state->stack[spi].spilled_ptr,
1283                               reg_state->stack[spi].spilled_ptr.parent);
1284                 return 0;
1285         } else {
1286                 int zeros = 0;
1287 
1288                 for (i = 0; i < size; i++) {
1289                         if (stype[(slot - i) % BPF_REG_SIZE] == STACK_MISC)
1290                                 continue;
1291                         if (stype[(slot - i) % BPF_REG_SIZE] == STACK_ZERO) {
1292                                 zeros++;
1293                                 continue;
1294                         }
1295                         verbose(env, "invalid read from stack off %d+%d size %d\n",
1296                                 off, i, size);
1297                         return -EACCES;
1298                 }
1299                 mark_reg_read(env, &reg_state->stack[spi].spilled_ptr,
1300                               reg_state->stack[spi].spilled_ptr.parent);
1301                 if (value_regno >= 0) {
1302                         if (zeros == size) {
1303                                 /* any size read into register is zero extended,
1304                                  * so the whole register == const_zero
1305                                  */
1306                                 __mark_reg_const_zero(&state->regs[value_regno]);
1307                         } else {
1308                                 /* have read misc data from the stack */
1309                                 mark_reg_unknown(env, state->regs, value_regno);
1310                         }
1311                         state->regs[value_regno].live |= REG_LIVE_WRITTEN;
1312                 }
1313                 return 0;
1314         }
1315 }
1316 
1317 /* check read/write into map element returned by bpf_map_lookup_elem() */
1318 static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
1319                               int size, bool zero_size_allowed)
1320 {
1321         struct bpf_reg_state *regs = cur_regs(env);
1322         struct bpf_map *map = regs[regno].map_ptr;
1323 
1324         if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) ||
1325             off + size > map->value_size) {
1326                 verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
1327                         map->value_size, off, size);
1328                 return -EACCES;
1329         }
1330         return 0;
1331 }
1332 
1333 /* check read/write into a map element with possible variable offset */
1334 static int check_map_access(struct bpf_verifier_env *env, u32 regno,
1335                             int off, int size, bool zero_size_allowed)
1336 {
1337         struct bpf_verifier_state *vstate = env->cur_state;
1338         struct bpf_func_state *state = vstate->frame[vstate->curframe];
1339         struct bpf_reg_state *reg = &state->regs[regno];
1340         int err;
1341 
1342         /* We may have adjusted the register to this map value, so we
1343          * need to try adding each of min_value and max_value to off
1344          * to make sure our theoretical access will be safe.
1345          */
1346         if (env->log.level)
1347                 print_verifier_state(env, state);
1348         /* The minimum value is only important with signed
1349          * comparisons where we can't assume the floor of a
1350          * value is 0.  If we are using signed variables for our
1351          * index'es we need to make sure that whatever we use
1352          * will have a set floor within our range.
1353          */
1354         if (reg->smin_value < 0) {
1355                 verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
1356                         regno);
1357                 return -EACCES;
1358         }
1359         err = __check_map_access(env, regno, reg->smin_value + off, size,
1360                                  zero_size_allowed);
1361         if (err) {
1362                 verbose(env, "R%d min value is outside of the array range\n",
1363                         regno);
1364                 return err;
1365         }
1366 
1367         /* If we haven't set a max value then we need to bail since we can't be
1368          * sure we won't do bad things.
1369          * If reg->umax_value + off could overflow, treat that as unbounded too.
1370          */
1371         if (reg->umax_value >= BPF_MAX_VAR_OFF) {
1372                 verbose(env, "R%d unbounded memory access, make sure to bounds check any array access into a map\n",
1373                         regno);
1374                 return -EACCES;
1375         }
1376         err = __check_map_access(env, regno, reg->umax_value + off, size,
1377                                  zero_size_allowed);
1378         if (err)
1379                 verbose(env, "R%d max value is outside of the array range\n",
1380                         regno);
1381         return err;
1382 }
1383 
1384 #define MAX_PACKET_OFF 0xffff
1385 
1386 static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
1387                                        const struct bpf_call_arg_meta *meta,
1388                                        enum bpf_access_type t)
1389 {
1390         switch (env->prog->type) {
1391         /* Program types only with direct read access go here! */
1392         case BPF_PROG_TYPE_LWT_IN:
1393         case BPF_PROG_TYPE_LWT_OUT:
1394         case BPF_PROG_TYPE_LWT_SEG6LOCAL:
1395         case BPF_PROG_TYPE_SK_REUSEPORT:
1396         case BPF_PROG_TYPE_FLOW_DISSECTOR:
1397         case BPF_PROG_TYPE_CGROUP_SKB:
1398                 if (t == BPF_WRITE)
1399                         return false;
1400                 /* fallthrough */
1401 
1402         /* Program types with direct read + write access go here! */
1403         case BPF_PROG_TYPE_SCHED_CLS:
1404         case BPF_PROG_TYPE_SCHED_ACT:
1405         case BPF_PROG_TYPE_XDP:
1406         case BPF_PROG_TYPE_LWT_XMIT:
1407         case BPF_PROG_TYPE_SK_SKB:
1408         case BPF_PROG_TYPE_SK_MSG:
1409                 if (meta)
1410                         return meta->pkt_access;
1411 
1412                 env->seen_direct_write = true;
1413                 return true;
1414         default:
1415                 return false;
1416         }
1417 }
1418 
1419 static int __check_packet_access(struct bpf_verifier_env *env, u32 regno,
1420                                  int off, int size, bool zero_size_allowed)
1421 {
1422         struct bpf_reg_state *regs = cur_regs(env);
1423         struct bpf_reg_state *reg = &regs[regno];
1424 
1425         if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) ||
1426             (u64)off + size > reg->range) {
1427                 verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
1428                         off, size, regno, reg->id, reg->off, reg->range);
1429                 return -EACCES;
1430         }
1431         return 0;
1432 }
1433 
1434 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
1435                                int size, bool zero_size_allowed)
1436 {
1437         struct bpf_reg_state *regs = cur_regs(env);
1438         struct bpf_reg_state *reg = &regs[regno];
1439         int err;
1440 
1441         /* We may have added a variable offset to the packet pointer; but any
1442          * reg->range we have comes after that.  We are only checking the fixed
1443          * offset.
1444          */
1445 
1446         /* We don't allow negative numbers, because we aren't tracking enough
1447          * detail to prove they're safe.
1448          */
1449         if (reg->smin_value < 0) {
1450                 verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
1451                         regno);
1452                 return -EACCES;
1453         }
1454         err = __check_packet_access(env, regno, off, size, zero_size_allowed);
1455         if (err) {
1456                 verbose(env, "R%d offset is outside of the packet\n", regno);
1457                 return err;
1458         }
1459         return err;
1460 }
1461 
1462 /* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
1463 static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
1464                             enum bpf_access_type t, enum bpf_reg_type *reg_type)
1465 {
1466         struct bpf_insn_access_aux info = {
1467                 .reg_type = *reg_type,
1468         };
1469 
1470         if (env->ops->is_valid_access &&
1471             env->ops->is_valid_access(off, size, t, env->prog, &info)) {
1472                 /* A non zero info.ctx_field_size indicates that this field is a
1473                  * candidate for later verifier transformation to load the whole
1474                  * field and then apply a mask when accessed with a narrower
1475                  * access than actual ctx access size. A zero info.ctx_field_size
1476                  * will only allow for whole field access and rejects any other
1477                  * type of narrower access.
1478                  */
1479                 *reg_type = info.reg_type;
1480 
1481                 env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
1482                 /* remember the offset of last byte accessed in ctx */
1483                 if (env->prog->aux->max_ctx_offset < off + size)
1484                         env->prog->aux->max_ctx_offset = off + size;
1485                 return 0;
1486         }
1487 
1488         verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
1489         return -EACCES;
1490 }
1491 
1492 static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
1493                                   int size)
1494 {
1495         if (size < 0 || off < 0 ||
1496             (u64)off + size > sizeof(struct bpf_flow_keys)) {
1497                 verbose(env, "invalid access to flow keys off=%d size=%d\n",
1498                         off, size);
1499                 return -EACCES;
1500         }
1501         return 0;
1502 }
1503 
1504 static int check_sock_access(struct bpf_verifier_env *env, u32 regno, int off,
1505                              int size, enum bpf_access_type t)
1506 {
1507         struct bpf_reg_state *regs = cur_regs(env);
1508         struct bpf_reg_state *reg = &regs[regno];
1509         struct bpf_insn_access_aux info;
1510 
1511         if (reg->smin_value < 0) {
1512                 verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
1513                         regno);
1514                 return -EACCES;
1515         }
1516 
1517         if (!bpf_sock_is_valid_access(off, size, t, &info)) {
1518                 verbose(env, "invalid bpf_sock access off=%d size=%d\n",
1519                         off, size);
1520                 return -EACCES;
1521         }
1522 
1523         return 0;
1524 }
1525 
1526 static bool __is_pointer_value(bool allow_ptr_leaks,
1527                                const struct bpf_reg_state *reg)
1528 {
1529         if (allow_ptr_leaks)
1530                 return false;
1531 
1532         return reg->type != SCALAR_VALUE;
1533 }
1534 
1535 static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
1536 {
1537         return cur_regs(env) + regno;
1538 }
1539 
1540 static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
1541 {
1542         return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
1543 }
1544 
1545 static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
1546 {
1547         const struct bpf_reg_state *reg = reg_state(env, regno);
1548 
1549         return reg->type == PTR_TO_CTX ||
1550                reg->type == PTR_TO_SOCKET;
1551 }
1552 
1553 static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
1554 {
1555         const struct bpf_reg_state *reg = reg_state(env, regno);
1556 
1557         return type_is_pkt_pointer(reg->type);
1558 }
1559 
1560 static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
1561 {
1562         const struct bpf_reg_state *reg = reg_state(env, regno);
1563 
1564         /* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
1565         return reg->type == PTR_TO_FLOW_KEYS;
1566 }
1567 
1568 static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
1569                                    const struct bpf_reg_state *reg,
1570                                    int off, int size, bool strict)
1571 {
1572         struct tnum reg_off;
1573         int ip_align;
1574 
1575         /* Byte size accesses are always allowed. */
1576         if (!strict || size == 1)
1577                 return 0;
1578 
1579         /* For platforms that do not have a Kconfig enabling
1580          * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
1581          * NET_IP_ALIGN is universally set to '2'.  And on platforms
1582          * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
1583          * to this code only in strict mode where we want to emulate
1584          * the NET_IP_ALIGN==2 checking.  Therefore use an
1585          * unconditional IP align value of '2'.
1586          */
1587         ip_align = 2;
1588 
1589         reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
1590         if (!tnum_is_aligned(reg_off, size)) {
1591                 char tn_buf[48];
1592 
1593                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
1594                 verbose(env,
1595                         "misaligned packet access off %d+%s+%d+%d size %d\n",
1596                         ip_align, tn_buf, reg->off, off, size);
1597                 return -EACCES;
1598         }
1599 
1600         return 0;
1601 }
1602 
1603 static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
1604                                        const struct bpf_reg_state *reg,
1605                                        const char *pointer_desc,
1606                                        int off, int size, bool strict)
1607 {
1608         struct tnum reg_off;
1609 
1610         /* Byte size accesses are always allowed. */
1611         if (!strict || size == 1)
1612                 return 0;
1613 
1614         reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
1615         if (!tnum_is_aligned(reg_off, size)) {
1616                 char tn_buf[48];
1617 
1618                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
1619                 verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
1620                         pointer_desc, tn_buf, reg->off, off, size);
1621                 return -EACCES;
1622         }
1623 
1624         return 0;
1625 }
1626 
1627 static int check_ptr_alignment(struct bpf_verifier_env *env,
1628                                const struct bpf_reg_state *reg, int off,
1629                                int size, bool strict_alignment_once)
1630 {
1631         bool strict = env->strict_alignment || strict_alignment_once;
1632         const char *pointer_desc = "";
1633 
1634         switch (reg->type) {
1635         case PTR_TO_PACKET:
1636         case PTR_TO_PACKET_META:
1637                 /* Special case, because of NET_IP_ALIGN. Given metadata sits
1638                  * right in front, treat it the very same way.
1639                  */
1640                 return check_pkt_ptr_alignment(env, reg, off, size, strict);
1641         case PTR_TO_FLOW_KEYS:
1642                 pointer_desc = "flow keys ";
1643                 break;
1644         case PTR_TO_MAP_VALUE:
1645                 pointer_desc = "value ";
1646                 break;
1647         case PTR_TO_CTX:
1648                 pointer_desc = "context ";
1649                 break;
1650         case PTR_TO_STACK:
1651                 pointer_desc = "stack ";
1652                 /* The stack spill tracking logic in check_stack_write()
1653                  * and check_stack_read() relies on stack accesses being
1654                  * aligned.
1655                  */
1656                 strict = true;
1657                 break;
1658         case PTR_TO_SOCKET:
1659                 pointer_desc = "sock ";
1660                 break;
1661         default:
1662                 break;
1663         }
1664         return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
1665                                            strict);
1666 }
1667 
1668 static int update_stack_depth(struct bpf_verifier_env *env,
1669                               const struct bpf_func_state *func,
1670                               int off)
1671 {
1672         u16 stack = env->subprog_info[func->subprogno].stack_depth;
1673 
1674         if (stack >= -off)
1675                 return 0;
1676 
1677         /* update known max for given subprogram */
1678         env->subprog_info[func->subprogno].stack_depth = -off;
1679         return 0;
1680 }
1681 
1682 /* starting from main bpf function walk all instructions of the function
1683  * and recursively walk all callees that given function can call.
1684  * Ignore jump and exit insns.
1685  * Since recursion is prevented by check_cfg() this algorithm
1686  * only needs a local stack of MAX_CALL_FRAMES to remember callsites
1687  */
1688 static int check_max_stack_depth(struct bpf_verifier_env *env)
1689 {
1690         int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
1691         struct bpf_subprog_info *subprog = env->subprog_info;
1692         struct bpf_insn *insn = env->prog->insnsi;
1693         int ret_insn[MAX_CALL_FRAMES];
1694         int ret_prog[MAX_CALL_FRAMES];
1695 
1696 process_func:
1697         /* round up to 32-bytes, since this is granularity
1698          * of interpreter stack size
1699          */
1700         depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
1701         if (depth > MAX_BPF_STACK) {
1702                 verbose(env, "combined stack size of %d calls is %d. Too large\n",
1703                         frame + 1, depth);
1704                 return -EACCES;
1705         }
1706 continue_func:
1707         subprog_end = subprog[idx + 1].start;
1708         for (; i < subprog_end; i++) {
1709                 if (insn[i].code != (BPF_JMP | BPF_CALL))
1710                         continue;
1711                 if (insn[i].src_reg != BPF_PSEUDO_CALL)
1712                         continue;
1713                 /* remember insn and function to return to */
1714                 ret_insn[frame] = i + 1;
1715                 ret_prog[frame] = idx;
1716 
1717                 /* find the callee */
1718                 i = i + insn[i].imm + 1;
1719                 idx = find_subprog(env, i);
1720                 if (idx < 0) {
1721                         WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
1722                                   i);
1723                         return -EFAULT;
1724                 }
1725                 frame++;
1726                 if (frame >= MAX_CALL_FRAMES) {
1727                         WARN_ONCE(1, "verifier bug. Call stack is too deep\n");
1728                         return -EFAULT;
1729                 }
1730                 goto process_func;
1731         }
1732         /* end of for() loop means the last insn of the 'subprog'
1733          * was reached. Doesn't matter whether it was JA or EXIT
1734          */
1735         if (frame == 0)
1736                 return 0;
1737         depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
1738         frame--;
1739         i = ret_insn[frame];
1740         idx = ret_prog[frame];
1741         goto continue_func;
1742 }
1743 
1744 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
1745 static int get_callee_stack_depth(struct bpf_verifier_env *env,
1746                                   const struct bpf_insn *insn, int idx)
1747 {
1748         int start = idx + insn->imm + 1, subprog;
1749 
1750         subprog = find_subprog(env, start);
1751         if (subprog < 0) {
1752                 WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
1753                           start);
1754                 return -EFAULT;
1755         }
1756         return env->subprog_info[subprog].stack_depth;
1757 }
1758 #endif
1759 
1760 static int check_ctx_reg(struct bpf_verifier_env *env,
1761                          const struct bpf_reg_state *reg, int regno)
1762 {
1763         /* Access to ctx or passing it to a helper is only allowed in
1764          * its original, unmodified form.
1765          */
1766 
1767         if (reg->off) {
1768                 verbose(env, "dereference of modified ctx ptr R%d off=%d disallowed\n",
1769                         regno, reg->off);
1770                 return -EACCES;
1771         }
1772 
1773         if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
1774                 char tn_buf[48];
1775 
1776                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
1777                 verbose(env, "variable ctx access var_off=%s disallowed\n", tn_buf);
1778                 return -EACCES;
1779         }
1780 
1781         return 0;
1782 }
1783 
1784 /* truncate register to smaller size (in bytes)
1785  * must be called with size < BPF_REG_SIZE
1786  */
1787 static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
1788 {
1789         u64 mask;
1790 
1791         /* clear high bits in bit representation */
1792         reg->var_off = tnum_cast(reg->var_off, size);
1793 
1794         /* fix arithmetic bounds */
1795         mask = ((u64)1 << (size * 8)) - 1;
1796         if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
1797                 reg->umin_value &= mask;
1798                 reg->umax_value &= mask;
1799         } else {
1800                 reg->umin_value = 0;
1801                 reg->umax_value = mask;
1802         }
1803         reg->smin_value = reg->umin_value;
1804         reg->smax_value = reg->umax_value;
1805 }
1806 
1807 /* check whether memory at (regno + off) is accessible for t = (read | write)
1808  * if t==write, value_regno is a register which value is stored into memory
1809  * if t==read, value_regno is a register which will receive the value from memory
1810  * if t==write && value_regno==-1, some unknown value is stored into memory
1811  * if t==read && value_regno==-1, don't care what we read from memory
1812  */
1813 static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
1814                             int off, int bpf_size, enum bpf_access_type t,
1815                             int value_regno, bool strict_alignment_once)
1816 {
1817         struct bpf_reg_state *regs = cur_regs(env);
1818         struct bpf_reg_state *reg = regs + regno;
1819         struct bpf_func_state *state;
1820         int size, err = 0;
1821 
1822         size = bpf_size_to_bytes(bpf_size);
1823         if (size < 0)
1824                 return size;
1825 
1826         /* alignment checks will add in reg->off themselves */
1827         err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
1828         if (err)
1829                 return err;
1830 
1831         /* for access checks, reg->off is just part of off */
1832         off += reg->off;
1833 
1834         if (reg->type == PTR_TO_MAP_VALUE) {
1835                 if (t == BPF_WRITE && value_regno >= 0 &&
1836                     is_pointer_value(env, value_regno)) {
1837                         verbose(env, "R%d leaks addr into map\n", value_regno);
1838                         return -EACCES;
1839                 }
1840 
1841                 err = check_map_access(env, regno, off, size, false);
1842                 if (!err && t == BPF_READ && value_regno >= 0)
1843                         mark_reg_unknown(env, regs, value_regno);
1844 
1845         } else if (reg->type == PTR_TO_CTX) {
1846                 enum bpf_reg_type reg_type = SCALAR_VALUE;
1847 
1848                 if (t == BPF_WRITE && value_regno >= 0 &&
1849                     is_pointer_value(env, value_regno)) {
1850                         verbose(env, "R%d leaks addr into ctx\n", value_regno);
1851                         return -EACCES;
1852                 }
1853 
1854                 err = check_ctx_reg(env, reg, regno);
1855                 if (err < 0)
1856                         return err;
1857 
1858                 err = check_ctx_access(env, insn_idx, off, size, t, &reg_type);
1859                 if (!err && t == BPF_READ && value_regno >= 0) {
1860                         /* ctx access returns either a scalar, or a
1861                          * PTR_TO_PACKET[_META,_END]. In the latter
1862                          * case, we know the offset is zero.
1863                          */
1864                         if (reg_type == SCALAR_VALUE)
1865                                 mark_reg_unknown(env, regs, value_regno);
1866                         else
1867                                 mark_reg_known_zero(env, regs,
1868                                                     value_regno);
1869                         regs[value_regno].type = reg_type;
1870                 }
1871 
1872         } else if (reg->type == PTR_TO_STACK) {
1873                 /* stack accesses must be at a fixed offset, so that we can
1874                  * determine what type of data were returned.
1875                  * See check_stack_read().
1876                  */
1877                 if (!tnum_is_const(reg->var_off)) {
1878                         char tn_buf[48];
1879 
1880                         tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
1881                         verbose(env, "variable stack access var_off=%s off=%d size=%d",
1882                                 tn_buf, off, size);
1883                         return -EACCES;
1884                 }
1885                 off += reg->var_off.value;
1886                 if (off >= 0 || off < -MAX_BPF_STACK) {
1887                         verbose(env, "invalid stack off=%d size=%d\n", off,
1888                                 size);
1889                         return -EACCES;
1890                 }
1891 
1892                 state = func(env, reg);
1893                 err = update_stack_depth(env, state, off);
1894                 if (err)
1895                         return err;
1896 
1897                 if (t == BPF_WRITE)
1898                         err = check_stack_write(env, state, off, size,
1899                                                 value_regno, insn_idx);
1900                 else
1901                         err = check_stack_read(env, state, off, size,
1902                                                value_regno);
1903         } else if (reg_is_pkt_pointer(reg)) {
1904                 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
1905                         verbose(env, "cannot write into packet\n");
1906                         return -EACCES;
1907                 }
1908                 if (t == BPF_WRITE && value_regno >= 0 &&
1909                     is_pointer_value(env, value_regno)) {
1910                         verbose(env, "R%d leaks addr into packet\n",
1911                                 value_regno);
1912                         return -EACCES;
1913                 }
1914                 err = check_packet_access(env, regno, off, size, false);
1915                 if (!err && t == BPF_READ && value_regno >= 0)
1916                         mark_reg_unknown(env, regs, value_regno);
1917         } else if (reg->type == PTR_TO_FLOW_KEYS) {
1918                 if (t == BPF_WRITE && value_regno >= 0 &&
1919                     is_pointer_value(env, value_regno)) {
1920                         verbose(env, "R%d leaks addr into flow keys\n",
1921                                 value_regno);
1922                         return -EACCES;
1923                 }
1924 
1925                 err = check_flow_keys_access(env, off, size);
1926                 if (!err && t == BPF_READ && value_regno >= 0)
1927                         mark_reg_unknown(env, regs, value_regno);
1928         } else if (reg->type == PTR_TO_SOCKET) {
1929                 if (t == BPF_WRITE) {
1930                         verbose(env, "cannot write into socket\n");
1931                         return -EACCES;
1932                 }
1933                 err = check_sock_access(env, regno, off, size, t);
1934                 if (!err && value_regno >= 0)
1935                         mark_reg_unknown(env, regs, value_regno);
1936         } else {
1937                 verbose(env, "R%d invalid mem access '%s'\n", regno,
1938                         reg_type_str[reg->type]);
1939                 return -EACCES;
1940         }
1941 
1942         if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
1943             regs[value_regno].type == SCALAR_VALUE) {
1944                 /* b/h/w load zero-extends, mark upper bits as known 0 */
1945                 coerce_reg_to_size(&regs[value_regno], size);
1946         }
1947         return err;
1948 }
1949 
1950 static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
1951 {
1952         int err;
1953 
1954         if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
1955             insn->imm != 0) {
1956                 verbose(env, "BPF_XADD uses reserved fields\n");
1957                 return -EINVAL;
1958         }
1959 
1960         /* check src1 operand */
1961         err = check_reg_arg(env, insn->src_reg, SRC_OP);
1962         if (err)
1963                 return err;
1964 
1965         /* check src2 operand */
1966         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
1967         if (err)
1968                 return err;
1969 
1970         if (is_pointer_value(env, insn->src_reg)) {
1971                 verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
1972                 return -EACCES;
1973         }
1974 
1975         if (is_ctx_reg(env, insn->dst_reg) ||
1976             is_pkt_reg(env, insn->dst_reg) ||
1977             is_flow_key_reg(env, insn->dst_reg)) {
1978                 verbose(env, "BPF_XADD stores into R%d %s is not allowed\n",
1979                         insn->dst_reg,
1980                         reg_type_str[reg_state(env, insn->dst_reg)->type]);
1981                 return -EACCES;
1982         }
1983 
1984         /* check whether atomic_add can read the memory */
1985         err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
1986                                BPF_SIZE(insn->code), BPF_READ, -1, true);
1987         if (err)
1988                 return err;
1989 
1990         /* check whether atomic_add can write into the same memory */
1991         return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
1992                                 BPF_SIZE(insn->code), BPF_WRITE, -1, true);
1993 }
1994 
1995 /* when register 'regno' is passed into function that will read 'access_size'
1996  * bytes from that pointer, make sure that it's within stack boundary
1997  * and all elements of stack are initialized.
1998  * Unlike most pointer bounds-checking functions, this one doesn't take an
1999  * 'off' argument, so it has to add in reg->off itself.
2000  */
2001 static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
2002                                 int access_size, bool zero_size_allowed,
2003                                 struct bpf_call_arg_meta *meta)
2004 {
2005         struct bpf_reg_state *reg = reg_state(env, regno);
2006         struct bpf_func_state *state = func(env, reg);
2007         int off, i, slot, spi;
2008 
2009         if (reg->type != PTR_TO_STACK) {
2010                 /* Allow zero-byte read from NULL, regardless of pointer type */
2011                 if (zero_size_allowed && access_size == 0 &&
2012                     register_is_null(reg))
2013                         return 0;
2014 
2015                 verbose(env, "R%d type=%s expected=%s\n", regno,
2016                         reg_type_str[reg->type],
2017                         reg_type_str[PTR_TO_STACK]);
2018                 return -EACCES;
2019         }
2020 
2021         /* Only allow fixed-offset stack reads */
2022         if (!tnum_is_const(reg->var_off)) {
2023                 char tn_buf[48];
2024 
2025                 tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
2026                 verbose(env, "invalid variable stack read R%d var_off=%s\n",
2027                         regno, tn_buf);
2028                 return -EACCES;
2029         }
2030         off = reg->off + reg->var_off.value;
2031         if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
2032             access_size < 0 || (access_size == 0 && !zero_size_allowed)) {
2033                 verbose(env, "invalid stack type R%d off=%d access_size=%d\n",
2034                         regno, off, access_size);
2035                 return -EACCES;
2036         }
2037 
2038         if (meta && meta->raw_mode) {
2039                 meta->access_size = access_size;
2040                 meta->regno = regno;
2041                 return 0;
2042         }
2043 
2044         for (i = 0; i < access_size; i++) {
2045                 u8 *stype;
2046 
2047                 slot = -(off + i) - 1;
2048                 spi = slot / BPF_REG_SIZE;
2049                 if (state->allocated_stack <= slot)
2050                         goto err;
2051                 stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
2052                 if (*stype == STACK_MISC)
2053                         goto mark;
2054                 if (*stype == STACK_ZERO) {
2055                         /* helper can write anything into the stack */
2056                         *stype = STACK_MISC;
2057                         goto mark;
2058                 }
2059 err:
2060                 verbose(env, "invalid indirect read from stack off %d+%d size %d\n",
2061                         off, i, access_size);
2062                 return -EACCES;
2063 mark:
2064                 /* reading any byte out of 8-byte 'spill_slot' will cause
2065                  * the whole slot to be marked as 'read'
2066                  */
2067                 mark_reg_read(env, &state->stack[spi].spilled_ptr,
2068                               state->stack[spi].spilled_ptr.parent);
2069         }
2070         return update_stack_depth(env, state, off);
2071 }
2072 
2073 static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
2074                                    int access_size, bool zero_size_allowed,
2075                                    struct bpf_call_arg_meta *meta)
2076 {
2077         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
2078 
2079         switch (reg->type) {
2080         case PTR_TO_PACKET:
2081         case PTR_TO_PACKET_META:
2082                 return check_packet_access(env, regno, reg->off, access_size,
2083                                            zero_size_allowed);
2084         case PTR_TO_MAP_VALUE:
2085                 return check_map_access(env, regno, reg->off, access_size,
2086                                         zero_size_allowed);
2087         default: /* scalar_value|ptr_to_stack or invalid ptr */
2088                 return check_stack_boundary(env, regno, access_size,
2089                                             zero_size_allowed, meta);
2090         }
2091 }
2092 
2093 static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
2094 {
2095         return type == ARG_PTR_TO_MEM ||
2096                type == ARG_PTR_TO_MEM_OR_NULL ||
2097                type == ARG_PTR_TO_UNINIT_MEM;
2098 }
2099 
2100 static bool arg_type_is_mem_size(enum bpf_arg_type type)
2101 {
2102         return type == ARG_CONST_SIZE ||
2103                type == ARG_CONST_SIZE_OR_ZERO;
2104 }
2105 
2106 static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
2107                           enum bpf_arg_type arg_type,
2108                           struct bpf_call_arg_meta *meta)
2109 {
2110         struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
2111         enum bpf_reg_type expected_type, type = reg->type;
2112         int err = 0;
2113 
2114         if (arg_type == ARG_DONTCARE)
2115                 return 0;
2116 
2117         err = check_reg_arg(env, regno, SRC_OP);
2118         if (err)
2119                 return err;
2120 
2121         if (arg_type == ARG_ANYTHING) {
2122                 if (is_pointer_value(env, regno)) {
2123                         verbose(env, "R%d leaks addr into helper function\n",
2124                                 regno);
2125                         return -EACCES;
2126                 }
2127                 return 0;
2128         }
2129 
2130         if (type_is_pkt_pointer(type) &&
2131             !may_access_direct_pkt_data(env, meta, BPF_READ)) {
2132                 verbose(env, "helper access to the packet is not allowed\n");
2133                 return -EACCES;
2134         }
2135 
2136         if (arg_type == ARG_PTR_TO_MAP_KEY ||
2137             arg_type == ARG_PTR_TO_MAP_VALUE ||
2138             arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) {
2139                 expected_type = PTR_TO_STACK;
2140                 if (!type_is_pkt_pointer(type) && type != PTR_TO_MAP_VALUE &&
2141                     type != expected_type)
2142                         goto err_type;
2143         } else if (arg_type == ARG_CONST_SIZE ||
2144                    arg_type == ARG_CONST_SIZE_OR_ZERO) {
2145                 expected_type = SCALAR_VALUE;
2146                 if (type != expected_type)
2147                         goto err_type;
2148         } else if (arg_type == ARG_CONST_MAP_PTR) {
2149                 expected_type = CONST_PTR_TO_MAP;
2150                 if (type != expected_type)
2151                         goto err_type;
2152         } else if (arg_type == ARG_PTR_TO_CTX) {
2153                 expected_type = PTR_TO_CTX;
2154                 if (type != expected_type)
2155                         goto err_type;
2156                 err = check_ctx_reg(env, reg, regno);
2157                 if (err < 0)
2158                         return err;
2159         } else if (arg_type == ARG_PTR_TO_SOCKET) {
2160                 expected_type = PTR_TO_SOCKET;
2161                 if (type != expected_type)
2162                         goto err_type;
2163                 if (meta->ptr_id || !reg->id) {
2164                         verbose(env, "verifier internal error: mismatched references meta=%d, reg=%d\n",
2165                                 meta->ptr_id, reg->id);
2166                         return -EFAULT;
2167                 }
2168                 meta->ptr_id = reg->id;
2169         } else if (arg_type_is_mem_ptr(arg_type)) {
2170                 expected_type = PTR_TO_STACK;
2171                 /* One exception here. In case function allows for NULL to be
2172                  * passed in as argument, it's a SCALAR_VALUE type. Final test
2173                  * happens during stack boundary checking.
2174                  */
2175                 if (register_is_null(reg) &&
2176                     arg_type == ARG_PTR_TO_MEM_OR_NULL)
2177                         /* final test in check_stack_boundary() */;
2178                 else if (!type_is_pkt_pointer(type) &&
2179                          type != PTR_TO_MAP_VALUE &&
2180                          type != expected_type)
2181                         goto err_type;
2182                 meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM;
2183         } else {
2184                 verbose(env, "unsupported arg_type %d\n", arg_type);
2185                 return -EFAULT;
2186         }
2187 
2188         if (arg_type == ARG_CONST_MAP_PTR) {
2189                 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
2190                 meta->map_ptr = reg->map_ptr;
2191         } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
2192                 /* bpf_map_xxx(..., map_ptr, ..., key) call:
2193                  * check that [key, key + map->key_size) are within
2194                  * stack limits and initialized
2195                  */
2196                 if (!meta->map_ptr) {
2197                         /* in function declaration map_ptr must come before
2198                          * map_key, so that it's verified and known before
2199                          * we have to check map_key here. Otherwise it means
2200                          * that kernel subsystem misconfigured verifier
2201                          */
2202                         verbose(env, "invalid map_ptr to access map->key\n");
2203                         return -EACCES;
2204                 }
2205                 err = check_helper_mem_access(env, regno,
2206                                               meta->map_ptr->key_size, false,
2207                                               NULL);
2208         } else if (arg_type == ARG_PTR_TO_MAP_VALUE ||
2209                    arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) {
2210                 /* bpf_map_xxx(..., map_ptr, ..., value) call:
2211                  * check [value, value + map->value_size) validity
2212                  */
2213                 if (!meta->map_ptr) {
2214                         /* kernel subsystem misconfigured verifier */
2215                         verbose(env, "invalid map_ptr to access map->value\n");
2216                         return -EACCES;
2217                 }
2218                 meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE);
2219                 err = check_helper_mem_access(env, regno,
2220                                               meta->map_ptr->value_size, false,
2221                                               meta);
2222         } else if (arg_type_is_mem_size(arg_type)) {
2223                 bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
2224 
2225                 /* remember the mem_size which may be used later
2226                  * to refine return values.
2227                  */
2228                 meta->msize_smax_value = reg->smax_value;
2229                 meta->msize_umax_value = reg->umax_value;
2230 
2231                 /* The register is SCALAR_VALUE; the access check
2232                  * happens using its boundaries.
2233                  */
2234                 if (!tnum_is_const(reg->var_off))
2235                         /* For unprivileged variable accesses, disable raw
2236                          * mode so that the program is required to
2237                          * initialize all the memory that the helper could
2238                          * just partially fill up.
2239                          */
2240                         meta = NULL;
2241 
2242                 if (reg->smin_value < 0) {
2243                         verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
2244                                 regno);
2245                         return -EACCES;
2246                 }
2247 
2248                 if (reg->umin_value == 0) {
2249                         err = check_helper_mem_access(env, regno - 1, 0,
2250                                                       zero_size_allowed,
2251                                                       meta);
2252                         if (err)
2253                                 return err;
2254                 }
2255 
2256                 if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
2257                         verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
2258                                 regno);
2259                         return -EACCES;
2260                 }
2261                 err = check_helper_mem_access(env, regno - 1,
2262                                               reg->umax_value,
2263                                               zero_size_allowed, meta);
2264         }
2265 
2266         return err;
2267 err_type:
2268         verbose(env, "R%d type=%s expected=%s\n", regno,
2269                 reg_type_str[type], reg_type_str[expected_type]);
2270         return -EACCES;
2271 }
2272 
2273 static int check_map_func_compatibility(struct bpf_verifier_env *env,
2274                                         struct bpf_map *map, int func_id)
2275 {
2276         if (!map)
2277                 return 0;
2278 
2279         /* We need a two way check, first is from map perspective ... */
2280         switch (map->map_type) {
2281         case BPF_MAP_TYPE_PROG_ARRAY:
2282                 if (func_id != BPF_FUNC_tail_call)
2283                         goto error;
2284                 break;
2285         case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
2286                 if (func_id != BPF_FUNC_perf_event_read &&
2287                     func_id != BPF_FUNC_perf_event_output &&
2288                     func_id != BPF_FUNC_perf_event_read_value)
2289                         goto error;
2290                 break;
2291         case BPF_MAP_TYPE_STACK_TRACE:
2292                 if (func_id != BPF_FUNC_get_stackid)
2293                         goto error;
2294                 break;
2295         case BPF_MAP_TYPE_CGROUP_ARRAY:
2296                 if (func_id != BPF_FUNC_skb_under_cgroup &&
2297                     func_id != BPF_FUNC_current_task_under_cgroup)
2298                         goto error;
2299                 break;
2300         case BPF_MAP_TYPE_CGROUP_STORAGE:
2301         case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
2302                 if (func_id != BPF_FUNC_get_local_storage)
2303                         goto error;
2304                 break;
2305         /* devmap returns a pointer to a live net_device ifindex that we cannot
2306          * allow to be modified from bpf side. So do not allow lookup elements
2307          * for now.
2308          */
2309         case BPF_MAP_TYPE_DEVMAP:
2310                 if (func_id != BPF_FUNC_redirect_map)
2311                         goto error;
2312                 break;
2313         /* Restrict bpf side of cpumap and xskmap, open when use-cases
2314          * appear.
2315          */
2316         case BPF_MAP_TYPE_CPUMAP:
2317         case BPF_MAP_TYPE_XSKMAP:
2318                 if (func_id != BPF_FUNC_redirect_map)
2319                         goto error;
2320                 break;
2321         case BPF_MAP_TYPE_ARRAY_OF_MAPS:
2322         case BPF_MAP_TYPE_HASH_OF_MAPS:
2323                 if (func_id != BPF_FUNC_map_lookup_elem)
2324                         goto error;
2325                 break;
2326         case BPF_MAP_TYPE_SOCKMAP:
2327                 if (func_id != BPF_FUNC_sk_redirect_map &&
2328                     func_id != BPF_FUNC_sock_map_update &&
2329                     func_id != BPF_FUNC_map_delete_elem &&
2330                     func_id != BPF_FUNC_msg_redirect_map)
2331                         goto error;
2332                 break;
2333         case BPF_MAP_TYPE_SOCKHASH:
2334                 if (func_id != BPF_FUNC_sk_redirect_hash &&
2335                     func_id != BPF_FUNC_sock_hash_update &&
2336                     func_id != BPF_FUNC_map_delete_elem &&
2337                     func_id != BPF_FUNC_msg_redirect_hash)
2338                         goto error;
2339                 break;
2340         case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
2341                 if (func_id != BPF_FUNC_sk_select_reuseport)
2342                         goto error;
2343                 break;
2344         case BPF_MAP_TYPE_QUEUE:
2345         case BPF_MAP_TYPE_STACK:
2346                 if (func_id != BPF_FUNC_map_peek_elem &&
2347                     func_id != BPF_FUNC_map_pop_elem &&
2348                     func_id != BPF_FUNC_map_push_elem)
2349                         goto error;
2350                 break;
2351         default:
2352                 break;
2353         }
2354 
2355         /* ... and second from the function itself. */
2356         switch (func_id) {
2357         case BPF_FUNC_tail_call:
2358                 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
2359                         goto error;
2360                 if (env->subprog_cnt > 1) {
2361                         verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
2362                         return -EINVAL;
2363                 }
2364                 break;
2365         case BPF_FUNC_perf_event_read:
2366         case BPF_FUNC_perf_event_output:
2367         case BPF_FUNC_perf_event_read_value:
2368                 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
2369                         goto error;
2370                 break;
2371         case BPF_FUNC_get_stackid:
2372                 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
2373                         goto error;
2374                 break;
2375         case BPF_FUNC_current_task_under_cgroup:
2376         case BPF_FUNC_skb_under_cgroup:
2377                 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
2378                         goto error;
2379                 break;
2380         case BPF_FUNC_redirect_map:
2381                 if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
2382                     map->map_type != BPF_MAP_TYPE_CPUMAP &&
2383                     map->map_type != BPF_MAP_TYPE_XSKMAP)
2384                         goto error;
2385                 break;
2386         case BPF_FUNC_sk_redirect_map:
2387         case BPF_FUNC_msg_redirect_map:
2388         case BPF_FUNC_sock_map_update:
2389                 if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
2390                         goto error;
2391                 break;
2392         case BPF_FUNC_sk_redirect_hash:
2393         case BPF_FUNC_msg_redirect_hash:
2394         case BPF_FUNC_sock_hash_update:
2395                 if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
2396                         goto error;
2397                 break;
2398         case BPF_FUNC_get_local_storage:
2399                 if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
2400                     map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
2401                         goto error;
2402                 break;
2403         case BPF_FUNC_sk_select_reuseport:
2404                 if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY)
2405                         goto error;
2406                 break;
2407         case BPF_FUNC_map_peek_elem:
2408         case BPF_FUNC_map_pop_elem:
2409         case BPF_FUNC_map_push_elem:
2410                 if (map->map_type != BPF_MAP_TYPE_QUEUE &&
2411                     map->map_type != BPF_MAP_TYPE_STACK)
2412                         goto error;
2413                 break;
2414         default:
2415                 break;
2416         }
2417 
2418         return 0;
2419 error:
2420         verbose(env, "cannot pass map_type %d into func %s#%d\n",
2421                 map->map_type, func_id_name(func_id), func_id);
2422         return -EINVAL;
2423 }
2424 
2425 static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
2426 {
2427         int count = 0;
2428 
2429         if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
2430                 count++;
2431         if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
2432                 count++;
2433         if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
2434                 count++;
2435         if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
2436                 count++;
2437         if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
2438                 count++;
2439 
2440         /* We only support one arg being in raw mode at the moment,
2441          * which is sufficient for the helper functions we have
2442          * right now.
2443          */
2444         return count <= 1;
2445 }
2446 
2447 static bool check_args_pair_invalid(enum bpf_arg_type arg_curr,
2448                                     enum bpf_arg_type arg_next)
2449 {
2450         return (arg_type_is_mem_ptr(arg_curr) &&
2451                 !arg_type_is_mem_size(arg_next)) ||
2452                (!arg_type_is_mem_ptr(arg_curr) &&
2453                 arg_type_is_mem_size(arg_next));
2454 }
2455 
2456 static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
2457 {
2458         /* bpf_xxx(..., buf, len) call will access 'len'
2459          * bytes from memory 'buf'. Both arg types need
2460          * to be paired, so make sure there's no buggy
2461          * helper function specification.
2462          */
2463         if (arg_type_is_mem_size(fn->arg1_type) ||
2464             arg_type_is_mem_ptr(fn->arg5_type)  ||
2465             check_args_pair_invalid(fn->arg1_type, fn->arg2_type) ||
2466             check_args_pair_invalid(fn->arg2_type, fn->arg3_type) ||
2467             check_args_pair_invalid(fn->arg3_type, fn->arg4_type) ||
2468             check_args_pair_invalid(fn->arg4_type, fn->arg5_type))
2469                 return false;
2470 
2471         return true;
2472 }
2473 
2474 static bool check_refcount_ok(const struct bpf_func_proto *fn)
2475 {
2476         int count = 0;
2477 
2478         if (arg_type_is_refcounted(fn->arg1_type))
2479                 count++;
2480         if (arg_type_is_refcounted(fn->arg2_type))
2481                 count++;
2482         if (arg_type_is_refcounted(fn->arg3_type))
2483                 count++;
2484         if (arg_type_is_refcounted(fn->arg4_type))
2485                 count++;
2486         if (arg_type_is_refcounted(fn->arg5_type))
2487                 count++;
2488 
2489         /* We only support one arg being unreferenced at the moment,
2490          * which is sufficient for the helper functions we have right now.
2491          */
2492         return count <= 1;
2493 }
2494 
2495 static int check_func_proto(const struct bpf_func_proto *fn)
2496 {
2497         return check_raw_mode_ok(fn) &&
2498                check_arg_pair_ok(fn) &&
2499                check_refcount_ok(fn) ? 0 : -EINVAL;
2500 }
2501 
2502 /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
2503  * are now invalid, so turn them into unknown SCALAR_VALUE.
2504  */
2505 static void __clear_all_pkt_pointers(struct bpf_verifier_env *env,
2506                                      struct bpf_func_state *state)
2507 {
2508         struct bpf_reg_state *regs = state->regs, *reg;
2509         int i;
2510 
2511         for (i = 0; i < MAX_BPF_REG; i++)
2512                 if (reg_is_pkt_pointer_any(&regs[i]))
2513                         mark_reg_unknown(env, regs, i);
2514 
2515         bpf_for_each_spilled_reg(i, state, reg) {
2516                 if (!reg)
2517                         continue;
2518                 if (reg_is_pkt_pointer_any(reg))
2519                         __mark_reg_unknown(reg);
2520         }
2521 }
2522 
2523 static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
2524 {
2525         struct bpf_verifier_state *vstate = env->cur_state;
2526         int i;
2527 
2528         for (i = 0; i <= vstate->curframe; i++)
2529                 __clear_all_pkt_pointers(env, vstate->frame[i]);
2530 }
2531 
2532 static void release_reg_references(struct bpf_verifier_env *env,
2533                                    struct bpf_func_state *state, int id)
2534 {
2535         struct bpf_reg_state *regs = state->regs, *reg;
2536         int i;
2537 
2538         for (i = 0; i < MAX_BPF_REG; i++)
2539                 if (regs[i].id == id)
2540                         mark_reg_unknown(env, regs, i);
2541 
2542         bpf_for_each_spilled_reg(i, state, reg) {
2543                 if (!reg)
2544                         continue;
2545                 if (reg_is_refcounted(reg) && reg->id == id)
2546                         __mark_reg_unknown(reg);
2547         }
2548 }
2549 
2550 /* The pointer with the specified id has released its reference to kernel
2551  * resources. Identify all copies of the same pointer and clear the reference.
2552  */
2553 static int release_reference(struct bpf_verifier_env *env,
2554                              struct bpf_call_arg_meta *meta)
2555 {
2556         struct bpf_verifier_state *vstate = env->cur_state;
2557         int i;
2558 
2559         for (i = 0; i <= vstate->curframe; i++)
2560                 release_reg_references(env, vstate->frame[i], meta->ptr_id);
2561 
2562         return release_reference_state(env, meta->ptr_id);
2563 }
2564 
2565 static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
2566                            int *insn_idx)
2567 {
2568         struct bpf_verifier_state *state = env->cur_state;
2569         struct bpf_func_state *caller, *callee;
2570         int i, err, subprog, target_insn;
2571 
2572         if (state->curframe + 1 >= MAX_CALL_FRAMES) {
2573                 verbose(env, "the call stack of %d frames is too deep\n",
2574                         state->curframe + 2);
2575                 return -E2BIG;
2576         }
2577 
2578         target_insn = *insn_idx + insn->imm;
2579         subprog = find_subprog(env, target_insn + 1);
2580         if (subprog < 0) {
2581                 verbose(env, "verifier bug. No program starts at insn %d\n",
2582                         target_insn + 1);
2583                 return -EFAULT;
2584         }
2585 
2586         caller = state->frame[state->curframe];
2587         if (state->frame[state->curframe + 1]) {
2588                 verbose(env, "verifier bug. Frame %d already allocated\n",
2589                         state->curframe + 1);
2590                 return -EFAULT;
2591         }
2592 
2593         callee = kzalloc(sizeof(*callee), GFP_KERNEL);
2594         if (!callee)
2595                 return -ENOMEM;
2596         state->frame[state->curframe + 1] = callee;
2597 
2598         /* callee cannot access r0, r6 - r9 for reading and has to write
2599          * into its own stack before reading from it.
2600          * callee can read/write into caller's stack
2601          */
2602         init_func_state(env, callee,
2603                         /* remember the callsite, it will be used by bpf_exit */
2604                         *insn_idx /* callsite */,
2605                         state->curframe + 1 /* frameno within this callchain */,
2606                         subprog /* subprog number within this prog */);
2607 
2608         /* Transfer references to the callee */
2609         err = transfer_reference_state(callee, caller);
2610         if (err)
2611                 return err;
2612 
2613         /* copy r1 - r5 args that callee can access.  The copy includes parent
2614          * pointers, which connects us up to the liveness chain
2615          */
2616         for (i = BPF_REG_1; i <= BPF_REG_5; i++)
2617                 callee->regs[i] = caller->regs[i];
2618 
2619         /* after the call registers r0 - r5 were scratched */
2620         for (i = 0; i < CALLER_SAVED_REGS; i++) {
2621                 mark_reg_not_init(env, caller->regs, caller_saved[i]);
2622                 check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
2623         }
2624 
2625         /* only increment it after check_reg_arg() finished */
2626         state->curframe++;
2627 
2628         /* and go analyze first insn of the callee */
2629         *insn_idx = target_insn;
2630 
2631         if (env->log.level) {
2632                 verbose(env, "caller:\n");
2633                 print_verifier_state(env, caller);
2634                 verbose(env, "callee:\n");
2635                 print_verifier_state(env, callee);
2636         }
2637         return 0;
2638 }
2639 
2640 static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
2641 {
2642         struct bpf_verifier_state *state = env->cur_state;
2643         struct bpf_func_state *caller, *callee;
2644         struct bpf_reg_state *r0;
2645         int err;
2646 
2647         callee = state->frame[state->curframe];
2648         r0 = &callee->regs[BPF_REG_0];
2649         if (r0->type == PTR_TO_STACK) {
2650                 /* technically it's ok to return caller's stack pointer
2651                  * (or caller's caller's pointer) back to the caller,
2652                  * since these pointers are valid. Only current stack
2653                  * pointer will be invalid as soon as function exits,
2654                  * but let's be conservative
2655                  */
2656                 verbose(env, "cannot return stack pointer to the caller\n");
2657                 return -EINVAL;
2658         }
2659 
2660         state->curframe--;
2661         caller = state->frame[state->curframe];
2662         /* return to the caller whatever r0 had in the callee */
2663         caller->regs[BPF_REG_0] = *r0;
2664 
2665         /* Transfer references to the caller */
2666         err = transfer_reference_state(caller, callee);
2667         if (err)
2668                 return err;
2669 
2670         *insn_idx = callee->callsite + 1;
2671         if (env->log.level) {
2672                 verbose(env, "returning from callee:\n");
2673                 print_verifier_state(env, callee);
2674                 verbose(env, "to caller at %d:\n", *insn_idx);
2675                 print_verifier_state(env, caller);
2676         }
2677         /* clear everything in the callee */
2678         free_func_state(callee);
2679         state->frame[state->curframe + 1] = NULL;
2680         return 0;
2681 }
2682 
2683 static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type,
2684                                    int func_id,
2685                                    struct bpf_call_arg_meta *meta)
2686 {
2687         struct bpf_reg_state *ret_reg = &regs[BPF_REG_0];
2688 
2689         if (ret_type != RET_INTEGER ||
2690             (func_id != BPF_FUNC_get_stack &&
2691              func_id != BPF_FUNC_probe_read_str))
2692                 return;
2693 
2694         ret_reg->smax_value = meta->msize_smax_value;
2695         ret_reg->umax_value = meta->msize_umax_value;
2696         __reg_deduce_bounds(ret_reg);
2697         __reg_bound_offset(ret_reg);
2698 }
2699 
2700 static int
2701 record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
2702                 int func_id, int insn_idx)
2703 {
2704         struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
2705 
2706         if (func_id != BPF_FUNC_tail_call &&
2707             func_id != BPF_FUNC_map_lookup_elem &&
2708             func_id != BPF_FUNC_map_update_elem &&
2709             func_id != BPF_FUNC_map_delete_elem &&
2710             func_id != BPF_FUNC_map_push_elem &&
2711             func_id != BPF_FUNC_map_pop_elem &&
2712             func_id != BPF_FUNC_map_peek_elem)
2713                 return 0;
2714 
2715         if (meta->map_ptr == NULL) {
2716                 verbose(env, "kernel subsystem misconfigured verifier\n");
2717                 return -EINVAL;
2718         }
2719 
2720         if (!BPF_MAP_PTR(aux->map_state))
2721                 bpf_map_ptr_store(aux, meta->map_ptr,
2722                                   meta->map_ptr->unpriv_array);
2723         else if (BPF_MAP_PTR(aux->map_state) != meta->map_ptr)
2724                 bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON,
2725                                   meta->map_ptr->unpriv_array);
2726         return 0;
2727 }
2728 
2729 static int check_reference_leak(struct bpf_verifier_env *env)
2730 {
2731         struct bpf_func_state *state = cur_func(env);
2732         int i;
2733 
2734         for (i = 0; i < state->acquired_refs; i++) {
2735                 verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
2736                         state->refs[i].id, state->refs[i].insn_idx);
2737         }
2738         return state->acquired_refs ? -EINVAL : 0;
2739 }
2740 
2741 static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
2742 {
2743         const struct bpf_func_proto *fn = NULL;
2744         struct bpf_reg_state *regs;
2745         struct bpf_call_arg_meta meta;
2746         bool changes_data;
2747         int i, err;
2748 
2749         /* find function prototype */
2750         if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
2751                 verbose(env, "invalid func %s#%d\n", func_id_name(func_id),
2752                         func_id);
2753                 return -EINVAL;
2754         }
2755 
2756         if (env->ops->get_func_proto)
2757                 fn = env->ops->get_func_proto(func_id, env->prog);
2758         if (!fn) {
2759                 verbose(env, "unknown func %s#%d\n", func_id_name(func_id),
2760                         func_id);
2761                 return -EINVAL;
2762         }
2763 
2764         /* eBPF programs must be GPL compatible to use GPL-ed functions */
2765         if (!env->prog->gpl_compatible && fn->gpl_only) {
2766                 verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
2767                 return -EINVAL;
2768         }
2769 
2770         /* With LD_ABS/IND some JITs save/restore skb from r1. */
2771         changes_data = bpf_helper_changes_pkt_data(fn->func);
2772         if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
2773                 verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
2774                         func_id_name(func_id), func_id);
2775                 return -EINVAL;
2776         }
2777 
2778         memset(&meta, 0, sizeof(meta));
2779         meta.pkt_access = fn->pkt_access;
2780 
2781         err = check_func_proto(fn);
2782         if (err) {
2783                 verbose(env, "kernel subsystem misconfigured func %s#%d\n",
2784                         func_id_name(func_id), func_id);
2785                 return err;
2786         }
2787 
2788         /* check args */
2789         err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
2790         if (err)
2791                 return err;
2792         err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
2793         if (err)
2794                 return err;
2795         err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
2796         if (err)
2797                 return err;
2798         err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
2799         if (err)
2800                 return err;
2801         err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
2802         if (err)
2803                 return err;
2804 
2805         err = record_func_map(env, &meta, func_id, insn_idx);
2806         if (err)
2807                 return err;
2808 
2809         /* Mark slots with STACK_MISC in case of raw mode, stack offset
2810          * is inferred from register state.
2811          */
2812         for (i = 0; i < meta.access_size; i++) {
2813                 err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
2814                                        BPF_WRITE, -1, false);
2815                 if (err)
2816                         return err;
2817         }
2818 
2819         if (func_id == BPF_FUNC_tail_call) {
2820                 err = check_reference_leak(env);
2821                 if (err) {
2822                         verbose(env, "tail_call would lead to reference leak\n");
2823                         return err;
2824                 }
2825         } else if (is_release_function(func_id)) {
2826                 err = release_reference(env, &meta);
2827                 if (err)
2828                         return err;
2829         }
2830 
2831         regs = cur_regs(env);
2832 
2833         /* check that flags argument in get_local_storage(map, flags) is 0,
2834          * this is required because get_local_storage() can't return an error.
2835          */
2836         if (func_id == BPF_FUNC_get_local_storage &&
2837             !register_is_null(&regs[BPF_REG_2])) {
2838                 verbose(env, "get_local_storage() doesn't support non-zero flags\n");
2839                 return -EINVAL;
2840         }
2841 
2842         /* reset caller saved regs */
2843         for (i = 0; i < CALLER_SAVED_REGS; i++) {
2844                 mark_reg_not_init(env, regs, caller_saved[i]);
2845                 check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
2846         }
2847 
2848         /* update return register (already marked as written above) */
2849         if (fn->ret_type == RET_INTEGER) {
2850                 /* sets type to SCALAR_VALUE */
2851                 mark_reg_unknown(env, regs, BPF_REG_0);
2852         } else if (fn->ret_type == RET_VOID) {
2853                 regs[BPF_REG_0].type = NOT_INIT;
2854         } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL ||
2855                    fn->ret_type == RET_PTR_TO_MAP_VALUE) {
2856                 /* There is no offset yet applied, variable or fixed */
2857                 mark_reg_known_zero(env, regs, BPF_REG_0);
2858                 /* remember map_ptr, so that check_map_access()
2859                  * can check 'value_size' boundary of memory access
2860                  * to map element returned from bpf_map_lookup_elem()
2861                  */
2862                 if (meta.map_ptr == NULL) {
2863                         verbose(env,
2864                                 "kernel subsystem misconfigured verifier\n");
2865                         return -EINVAL;
2866                 }
2867                 regs[BPF_REG_0].map_ptr = meta.map_ptr;
2868                 if (fn->ret_type == RET_PTR_TO_MAP_VALUE) {
2869                         regs[BPF_REG_0].type = PTR_TO_MAP_VALUE;
2870                 } else {
2871                         regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
2872                         regs[BPF_REG_0].id = ++env->id_gen;
2873                 }
2874         } else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) {
2875                 int id = acquire_reference_state(env, insn_idx);
2876                 if (id < 0)
2877                         return id;
2878                 mark_reg_known_zero(env, regs, BPF_REG_0);
2879                 regs[BPF_REG_0].type = PTR_TO_SOCKET_OR_NULL;
2880                 regs[BPF_REG_0].id = id;
2881         } else {
2882                 verbose(env, "unknown return type %d of func %s#%d\n",
2883                         fn->ret_type, func_id_name(func_id), func_id);
2884                 return -EINVAL;
2885         }
2886 
2887         do_refine_retval_range(regs, fn->ret_type, func_id, &meta);
2888 
2889         err = check_map_func_compatibility(env, meta.map_ptr, func_id);
2890         if (err)
2891                 return err;
2892 
2893         if (func_id == BPF_FUNC_get_stack && !env->prog->has_callchain_buf) {
2894                 const char *err_str;
2895 
2896 #ifdef CONFIG_PERF_EVENTS
2897                 err = get_callchain_buffers(sysctl_perf_event_max_stack);
2898                 err_str = "cannot get callchain buffer for func %s#%d\n";
2899 #else
2900                 err = -ENOTSUPP;
2901                 err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
2902 #endif
2903                 if (err) {
2904                         verbose(env, err_str, func_id_name(func_id), func_id);
2905                         return err;
2906                 }
2907 
2908                 env->prog->has_callchain_buf = true;
2909         }
2910 
2911         if (changes_data)
2912                 clear_all_pkt_pointers(env);
2913         return 0;
2914 }
2915 
2916 static bool signed_add_overflows(s64 a, s64 b)
2917 {
2918         /* Do the add in u64, where overflow is well-defined */
2919         s64 res = (s64)((u64)a + (u64)b);
2920 
2921         if (b < 0)
2922                 return res > a;
2923         return res < a;
2924 }
2925 
2926 static bool signed_sub_overflows(s64 a, s64 b)
2927 {
2928         /* Do the sub in u64, where overflow is well-defined */
2929         s64 res = (s64)((u64)a - (u64)b);
2930 
2931         if (b < 0)
2932                 return res < a;
2933         return res > a;
2934 }
2935 
2936 static bool check_reg_sane_offset(struct bpf_verifier_env *env,
2937                                   const struct bpf_reg_state *reg,
2938                                   enum bpf_reg_type type)
2939 {
2940         bool known = tnum_is_const(reg->var_off);
2941         s64 val = reg->var_off.value;
2942         s64 smin = reg->smin_value;
2943 
2944         if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
2945                 verbose(env, "math between %s pointer and %lld is not allowed\n",
2946                         reg_type_str[type], val);
2947                 return false;
2948         }
2949 
2950         if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
2951                 verbose(env, "%s pointer offset %d is not allowed\n",
2952                         reg_type_str[type], reg->off);
2953                 return false;
2954         }
2955 
2956         if (smin == S64_MIN) {
2957                 verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
2958                         reg_type_str[type]);
2959                 return false;
2960         }
2961 
2962         if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
2963                 verbose(env, "value %lld makes %s pointer be out of bounds\n",
2964                         smin, reg_type_str[type]);
2965                 return false;
2966         }
2967 
2968         return true;
2969 }
2970 
2971 /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
2972  * Caller should also handle BPF_MOV case separately.
2973  * If we return -EACCES, caller may want to try again treating pointer as a
2974  * scalar.  So we only emit a diagnostic if !env->allow_ptr_leaks.
2975  */
2976 static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
2977                                    struct bpf_insn *insn,
2978                                    const struct bpf_reg_state *ptr_reg,
2979                                    const struct bpf_reg_state *off_reg)
2980 {
2981         struct bpf_verifier_state *vstate = env->cur_state;
2982         struct bpf_func_state *state = vstate->frame[vstate->curframe];
2983         struct bpf_reg_state *regs = state->regs, *dst_reg;
2984         bool known = tnum_is_const(off_reg->var_off);
2985         s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
2986             smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
2987         u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
2988             umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
2989         u8 opcode = BPF_OP(insn->code);
2990         u32 dst = insn->dst_reg;
2991 
2992         dst_reg = &regs[dst];
2993 
2994         if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
2995             smin_val > smax_val || umin_val > umax_val) {
2996                 /* Taint dst register if offset had invalid bounds derived from
2997                  * e.g. dead branches.
2998                  */
2999                 __mark_reg_unknown(dst_reg);
3000                 return 0;
3001         }
3002 
3003         if (BPF_CLASS(insn->code) != BPF_ALU64) {
3004                 /* 32-bit ALU ops on pointers produce (meaningless) scalars */
3005                 verbose(env,
3006                         "R%d 32-bit pointer arithmetic prohibited\n",
3007                         dst);
3008                 return -EACCES;
3009         }
3010 
3011         switch (ptr_reg->type) {
3012         case PTR_TO_MAP_VALUE_OR_NULL:
3013                 verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
3014                         dst, reg_type_str[ptr_reg->type]);
3015                 return -EACCES;
3016         case CONST_PTR_TO_MAP:
3017         case PTR_TO_PACKET_END:
3018         case PTR_TO_SOCKET:
3019         case PTR_TO_SOCKET_OR_NULL:
3020                 verbose(env, "R%d pointer arithmetic on %s prohibited\n",
3021                         dst, reg_type_str[ptr_reg->type]);
3022                 return -EACCES;
3023         default:
3024                 break;
3025         }
3026 
3027         /* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
3028          * The id may be overwritten later if we create a new variable offset.
3029          */
3030         dst_reg->type = ptr_reg->type;
3031         dst_reg->id = ptr_reg->id;
3032 
3033         if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) ||
3034             !check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
3035                 return -EINVAL;
3036 
3037         switch (opcode) {
3038         case BPF_ADD:
3039                 /* We can take a fixed offset as long as it doesn't overflow
3040                  * the s32 'off' field
3041                  */
3042                 if (known && (ptr_reg->off + smin_val ==
3043                               (s64)(s32)(ptr_reg->off + smin_val))) {
3044                         /* pointer += K.  Accumulate it into fixed offset */
3045                         dst_reg->smin_value = smin_ptr;
3046                         dst_reg->smax_value = smax_ptr;
3047                         dst_reg->umin_value = umin_ptr;
3048                         dst_reg->umax_value = umax_ptr;
3049                         dst_reg->var_off = ptr_reg->var_off;
3050                         dst_reg->off = ptr_reg->off + smin_val;
3051                         dst_reg->raw = ptr_reg->raw;
3052                         break;
3053                 }
3054                 /* A new variable offset is created.  Note that off_reg->off
3055                  * == 0, since it's a scalar.
3056                  * dst_reg gets the pointer type and since some positive
3057                  * integer value was added to the pointer, give it a new 'id'
3058                  * if it's a PTR_TO_PACKET.
3059                  * this creates a new 'base' pointer, off_reg (variable) gets
3060                  * added into the variable offset, and we copy the fixed offset
3061                  * from ptr_reg.
3062                  */
3063                 if (signed_add_overflows(smin_ptr, smin_val) ||
3064                     signed_add_overflows(smax_ptr, smax_val)) {
3065                         dst_reg->smin_value = S64_MIN;
3066                         dst_reg->smax_value = S64_MAX;
3067                 } else {
3068                         dst_reg->smin_value = smin_ptr + smin_val;
3069                         dst_reg->smax_value = smax_ptr + smax_val;
3070                 }
3071                 if (umin_ptr + umin_val < umin_ptr ||
3072                     umax_ptr + umax_val < umax_ptr) {
3073                         dst_reg->umin_value = 0;
3074                         dst_reg->umax_value = U64_MAX;
3075                 } else {
3076                         dst_reg->umin_value = umin_ptr + umin_val;
3077                         dst_reg->umax_value = umax_ptr + umax_val;
3078                 }
3079                 dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
3080                 dst_reg->off = ptr_reg->off;
3081                 dst_reg->raw = ptr_reg->raw;
3082                 if (reg_is_pkt_pointer(ptr_reg)) {
3083                         dst_reg->id = ++env->id_gen;
3084                         /* something was added to pkt_ptr, set range to zero */
3085                         dst_reg->raw = 0;
3086                 }
3087                 break;
3088         case BPF_SUB:
3089                 if (dst_reg == off_reg) {
3090                         /* scalar -= pointer.  Creates an unknown scalar */
3091                         verbose(env, "R%d tried to subtract pointer from scalar\n",
3092                                 dst);
3093                         return -EACCES;
3094                 }
3095                 /* We don't allow subtraction from FP, because (according to
3096                  * test_verifier.c test "invalid fp arithmetic", JITs might not
3097                  * be able to deal with it.
3098                  */
3099                 if (ptr_reg->type == PTR_TO_STACK) {
3100                         verbose(env, "R%d subtraction from stack pointer prohibited\n",
3101                                 dst);
3102                         return -EACCES;
3103                 }
3104                 if (known && (ptr_reg->off - smin_val ==
3105                               (s64)(s32)(ptr_reg->off - smin_val))) {
3106                         /* pointer -= K.  Subtract it from fixed offset */
3107                         dst_reg->smin_value = smin_ptr;
3108                         dst_reg->smax_value = smax_ptr;
3109                         dst_reg->umin_value = umin_ptr;
3110                         dst_reg->umax_value = umax_ptr;
3111                         dst_reg->var_off = ptr_reg->var_off;
3112                         dst_reg->id = ptr_reg->id;
3113                         dst_reg->off = ptr_reg->off - smin_val;
3114                         dst_reg->raw = ptr_reg->raw;
3115                         break;
3116                 }
3117                 /* A new variable offset is created.  If the subtrahend is known
3118                  * nonnegative, then any reg->range we had before is still good.
3119                  */
3120                 if (signed_sub_overflows(smin_ptr, smax_val) ||
3121                     signed_sub_overflows(smax_ptr, smin_val)) {
3122                         /* Overflow possible, we know nothing */
3123                         dst_reg->smin_value = S64_MIN;
3124                         dst_reg->smax_value = S64_MAX;
3125                 } else {
3126                         dst_reg->smin_value = smin_ptr - smax_val;
3127                         dst_reg->smax_value = smax_ptr - smin_val;
3128                 }
3129                 if (umin_ptr < umax_val) {
3130                         /* Overflow possible, we know nothing */
3131                         dst_reg->umin_value = 0;
3132                         dst_reg->umax_value = U64_MAX;
3133                 } else {
3134                         /* Cannot overflow (as long as bounds are consistent) */
3135                         dst_reg->umin_value = umin_ptr - umax_val;
3136                         dst_reg->umax_value = umax_ptr - umin_val;
3137                 }
3138                 dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
3139                 dst_reg->off = ptr_reg->off;
3140                 dst_reg->raw = ptr_reg->raw;
3141                 if (reg_is_pkt_pointer(ptr_reg)) {
3142                         dst_reg->id = ++env->id_gen;
3143                         /* something was added to pkt_ptr, set range to zero */
3144                         if (smin_val < 0)
3145                                 dst_reg->raw = 0;
3146                 }
3147                 break;
3148         case BPF_AND:
3149         case BPF_OR:
3150         case BPF_XOR:
3151                 /* bitwise ops on pointers are troublesome, prohibit. */
3152                 verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
3153                         dst, bpf_alu_string[opcode >> 4]);
3154                 return -EACCES;
3155         default:
3156                 /* other operators (e.g. MUL,LSH) produce non-pointer results */
3157                 verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
3158                         dst, bpf_alu_string[opcode >> 4]);
3159                 return -EACCES;
3160         }
3161 
3162         if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type))
3163                 return -EINVAL;
3164 
3165         __update_reg_bounds(dst_reg);
3166         __reg_deduce_bounds(dst_reg);
3167         __reg_bound_offset(dst_reg);
3168         return 0;
3169 }
3170 
3171 /* WARNING: This function does calculations on 64-bit values, but the actual
3172  * execution may occur on 32-bit values. Therefore, things like bitshifts
3173  * need extra checks in the 32-bit case.
3174  */
3175 static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
3176                                       struct bpf_insn *insn,
3177                                       struct bpf_reg_state *dst_reg,
3178                                       struct bpf_reg_state src_reg)
3179 {
3180         struct bpf_reg_state *regs = cur_regs(env);
3181         u8 opcode = BPF_OP(insn->code);
3182         bool src_known, dst_known;
3183         s64 smin_val, smax_val;
3184         u64 umin_val, umax_val;
3185         u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
3186 
3187         if (insn_bitness == 32) {
3188                 /* Relevant for 32-bit RSH: Information can propagate towards
3189                  * LSB, so it isn't sufficient to only truncate the output to
3190                  * 32 bits.
3191                  */
3192                 coerce_reg_to_size(dst_reg, 4);
3193                 coerce_reg_to_size(&src_reg, 4);
3194         }
3195 
3196         smin_val = src_reg.smin_value;
3197         smax_val = src_reg.smax_value;
3198         umin_val = src_reg.umin_value;
3199         umax_val = src_reg.umax_value;
3200         src_known = tnum_is_const(src_reg.var_off);
3201         dst_known = tnum_is_const(dst_reg->var_off);
3202 
3203         if ((src_known && (smin_val != smax_val || umin_val != umax_val)) ||
3204             smin_val > smax_val || umin_val > umax_val) {
3205                 /* Taint dst register if offset had invalid bounds derived from
3206                  * e.g. dead branches.
3207                  */
3208                 __mark_reg_unknown(dst_reg);
3209                 return 0;
3210         }
3211 
3212         if (!src_known &&
3213             opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) {
3214                 __mark_reg_unknown(dst_reg);
3215                 return 0;
3216         }
3217 
3218         switch (opcode) {
3219         case BPF_ADD:
3220                 if (signed_add_overflows(dst_reg->smin_value, smin_val) ||
3221                     signed_add_overflows(dst_reg->smax_value, smax_val)) {
3222                         dst_reg->smin_value = S64_MIN;
3223                         dst_reg->smax_value = S64_MAX;
3224                 } else {
3225                         dst_reg->smin_value += smin_val;
3226                         dst_reg->smax_value += smax_val;
3227                 }
3228                 if (dst_reg->umin_value + umin_val < umin_val ||
3229                     dst_reg->umax_value + umax_val < umax_val) {
3230                         dst_reg->umin_value = 0;
3231                         dst_reg->umax_value = U64_MAX;
3232                 } else {
3233                         dst_reg->umin_value += umin_val;
3234                         dst_reg->umax_value += umax_val;
3235                 }
3236                 dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
3237                 break;
3238         case BPF_SUB:
3239                 if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
3240                     signed_sub_overflows(dst_reg->smax_value, smin_val)) {
3241                         /* Overflow possible, we know nothing */
3242                         dst_reg->smin_value = S64_MIN;
3243                         dst_reg->smax_value = S64_MAX;
3244                 } else {
3245                         dst_reg->smin_value -= smax_val;
3246                         dst_reg->smax_value -= smin_val;
3247                 }
3248                 if (dst_reg->umin_value < umax_val) {
3249                         /* Overflow possible, we know nothing */
3250                         dst_reg->umin_value = 0;
3251                         dst_reg->umax_value = U64_MAX;
3252                 } else {
3253                         /* Cannot overflow (as long as bounds are consistent) */
3254                         dst_reg->umin_value -= umax_val;
3255                         dst_reg->umax_value -= umin_val;
3256                 }
3257                 dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
3258                 break;
3259         case BPF_MUL:
3260                 dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
3261                 if (smin_val < 0 || dst_reg->smin_value < 0) {
3262                         /* Ain't nobody got time to multiply that sign */
3263                         __mark_reg_unbounded(dst_reg);
3264                         __update_reg_bounds(dst_reg);
3265                         break;
3266                 }
3267                 /* Both values are positive, so we can work with unsigned and
3268                  * copy the result to signed (unless it exceeds S64_MAX).
3269                  */
3270                 if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
3271                         /* Potential overflow, we know nothing */
3272                         __mark_reg_unbounded(dst_reg);
3273                         /* (except what we can learn from the var_off) */
3274                         __update_reg_bounds(dst_reg);
3275                         break;
3276                 }
3277                 dst_reg->umin_value *= umin_val;
3278                 dst_reg->umax_value *= umax_val;
3279                 if (dst_reg->umax_value > S64_MAX) {
3280                         /* Overflow possible, we know nothing */
3281                         dst_reg->smin_value = S64_MIN;
3282                         dst_reg->smax_value = S64_MAX;
3283                 } else {
3284                         dst_reg->smin_value = dst_reg->umin_value;
3285                         dst_reg->smax_value = dst_reg->umax_value;
3286                 }
3287                 break;
3288         case BPF_AND:
3289                 if (src_known && dst_known) {
3290                         __mark_reg_known(dst_reg, dst_reg->var_off.value &
3291                                                   src_reg.var_off.value);
3292                         break;
3293                 }
3294                 /* We get our minimum from the var_off, since that's inherently
3295                  * bitwise.  Our maximum is the minimum of the operands' maxima.
3296                  */
3297                 dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
3298                 dst_reg->umin_value = dst_reg->var_off.value;
3299                 dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
3300                 if (dst_reg->smin_value < 0 || smin_val < 0) {
3301                         /* Lose signed bounds when ANDing negative numbers,
3302                          * ain't nobody got time for that.
3303                          */
3304                         dst_reg->smin_value = S64_MIN;
3305                         dst_reg->smax_value = S64_MAX;
3306                 } else {
3307                         /* ANDing two positives gives a positive, so safe to
3308                          * cast result into s64.
3309                          */
3310                         dst_reg->smin_value = dst_reg->umin_value;
3311                         dst_reg->smax_value = dst_reg->umax_value;
3312                 }
3313                 /* We may learn something more from the var_off */
3314                 __update_reg_bounds(dst_reg);
3315                 break;
3316         case BPF_OR:
3317                 if (src_known && dst_known) {
3318                         __mark_reg_known(dst_reg, dst_reg->var_off.value |
3319                                                   src_reg.var_off.value);
3320                         break;
3321                 }
3322                 /* We get our maximum from the var_off, and our minimum is the
3323                  * maximum of the operands' minima
3324                  */
3325                 dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
3326                 dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
3327                 dst_reg->umax_value = dst_reg->var_off.value |
3328                                       dst_reg->var_off.mask;
3329                 if (dst_reg->smin_value < 0 || smin_val < 0) {
3330                         /* Lose signed bounds when ORing negative numbers,
3331                          * ain't nobody got time for that.
3332                          */
3333                         dst_reg->smin_value = S64_MIN;
3334                         dst_reg->smax_value = S64_MAX;
3335                 } else {
3336                         /* ORing two positives gives a positive, so safe to
3337                          * cast result into s64.
3338                          */
3339                         dst_reg->smin_value = dst_reg->umin_value;
3340                         dst_reg->smax_value = dst_reg->umax_value;
3341                 }
3342                 /* We may learn something more from the var_off */
3343                 __update_reg_bounds(dst_reg);
3344                 break;
3345         case BPF_LSH:
3346                 if (umax_val >= insn_bitness) {
3347                         /* Shifts greater than 31 or 63 are undefined.
3348                          * This includes shifts by a negative number.
3349                          */
3350                         mark_reg_unknown(env, regs, insn->dst_reg);
3351                         break;
3352                 }
3353                 /* We lose all sign bit information (except what we can pick
3354                  * up from var_off)
3355                  */
3356                 dst_reg->smin_value = S64_MIN;
3357                 dst_reg->smax_value = S64_MAX;
3358                 /* If we might shift our top bit out, then we know nothing */
3359                 if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
3360                         dst_reg->umin_value = 0;
3361                         dst_reg->umax_value = U64_MAX;
3362                 } else {
3363                         dst_reg->umin_value <<= umin_val;
3364                         dst_reg->umax_value <<= umax_val;
3365                 }
3366                 dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
3367                 /* We may learn something more from the var_off */
3368                 __update_reg_bounds(dst_reg);
3369                 break;
3370         case BPF_RSH:
3371                 if (umax_val >= insn_bitness) {
3372                         /* Shifts greater than 31 or 63 are undefined.
3373                          * This includes shifts by a negative number.
3374                          */
3375                         mark_reg_unknown(env, regs, insn->dst_reg);
3376                         break;
3377                 }
3378                 /* BPF_RSH is an unsigned shift.  If the value in dst_reg might
3379                  * be negative, then either:
3380                  * 1) src_reg might be zero, so the sign bit of the result is
3381                  *    unknown, so we lose our signed bounds
3382                  * 2) it's known negative, thus the unsigned bounds capture the
3383                  *    signed bounds
3384                  * 3) the signed bounds cross zero, so they tell us nothing
3385                  *    about the result
3386                  * If the value in dst_reg is known nonnegative, then again the
3387                  * unsigned bounts capture the signed bounds.
3388                  * Thus, in all cases it suffices to blow away our signed bounds
3389                  * and rely on inferring new ones from the unsigned bounds and
3390                  * var_off of the result.
3391                  */
3392                 dst_reg->smin_value = S64_MIN;
3393                 dst_reg->smax_value = S64_MAX;
3394                 dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
3395                 dst_reg->umin_value >>= umax_val;
3396                 dst_reg->umax_value >>= umin_val;
3397                 /* We may learn something more from the var_off */
3398                 __update_reg_bounds(dst_reg);
3399                 break;
3400         case BPF_ARSH:
3401                 if (umax_val >= insn_bitness) {
3402                         /* Shifts greater than 31 or 63 are undefined.
3403                          * This includes shifts by a negative number.
3404                          */
3405                         mark_reg_unknown(env, regs, insn->dst_reg);
3406                         break;
3407                 }
3408 
3409                 /* Upon reaching here, src_known is true and
3410                  * umax_val is equal to umin_val.
3411                  */
3412                 dst_reg->smin_value >>= umin_val;
3413                 dst_reg->smax_value >>= umin_val;
3414                 dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val);
3415 
3416                 /* blow away the dst_reg umin_value/umax_value and rely on
3417                  * dst_reg var_off to refine the result.
3418                  */
3419                 dst_reg->umin_value = 0;
3420                 dst_reg->umax_value = U64_MAX;
3421                 __update_reg_bounds(dst_reg);
3422                 break;
3423         default:
3424                 mark_reg_unknown(env, regs, insn->dst_reg);
3425                 break;
3426         }
3427 
3428         if (BPF_CLASS(insn->code) != BPF_ALU64) {
3429                 /* 32-bit ALU ops are (32,32)->32 */
3430                 coerce_reg_to_size(dst_reg, 4);
3431         }
3432 
3433         __reg_deduce_bounds(dst_reg);
3434         __reg_bound_offset(dst_reg);
3435         return 0;
3436 }
3437 
3438 /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
3439  * and var_off.
3440  */
3441 static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
3442                                    struct bpf_insn *insn)
3443 {
3444         struct bpf_verifier_state *vstate = env->cur_state;
3445         struct bpf_func_state *state = vstate->frame[vstate->curframe];
3446         struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
3447         struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
3448         u8 opcode = BPF_OP(insn->code);
3449 
3450         dst_reg = &regs[insn->dst_reg];
3451         src_reg = NULL;
3452         if (dst_reg->type != SCALAR_VALUE)
3453                 ptr_reg = dst_reg;
3454         if (BPF_SRC(insn->code) == BPF_X) {
3455                 src_reg = &regs[insn->src_reg];
3456                 if (src_reg->type != SCALAR_VALUE) {
3457                         if (dst_reg->type != SCALAR_VALUE) {
3458                                 /* Combining two pointers by any ALU op yields
3459                                  * an arbitrary scalar. Disallow all math except
3460                                  * pointer subtraction
3461                                  */
3462                                 if (opcode == BPF_SUB && env->allow_ptr_leaks) {
3463                                         mark_reg_unknown(env, regs, insn->dst_reg);
3464                                         return 0;
3465                                 }
3466                                 verbose(env, "R%d pointer %s pointer prohibited\n",
3467                                         insn->dst_reg,
3468                                         bpf_alu_string[opcode >> 4]);
3469                                 return -EACCES;
3470                         } else {
3471                                 /* scalar += pointer
3472                                  * This is legal, but we have to reverse our
3473                                  * src/dest handling in computing the range
3474                                  */
3475                                 return adjust_ptr_min_max_vals(env, insn,
3476                                                                src_reg, dst_reg);
3477                         }
3478                 } else if (ptr_reg) {
3479                         /* pointer += scalar */
3480                         return adjust_ptr_min_max_vals(env, insn,
3481                                                        dst_reg, src_reg);
3482                 }
3483         } else {
3484                 /* Pretend the src is a reg with a known value, since we only
3485                  * need to be able to read from this state.
3486                  */
3487                 off_reg.type = SCALAR_VALUE;
3488                 __mark_reg_known(&off_reg, insn->imm);
3489                 src_reg = &off_reg;
3490                 if (ptr_reg) /* pointer += K */
3491                         return adjust_ptr_min_max_vals(env, insn,
3492                                                        ptr_reg, src_reg);
3493         }
3494 
3495         /* Got here implies adding two SCALAR_VALUEs */
3496         if (WARN_ON_ONCE(ptr_reg)) {
3497                 print_verifier_state(env, state);
3498                 verbose(env, "verifier internal error: unexpected ptr_reg\n");
3499                 return -EINVAL;
3500         }
3501         if (WARN_ON(!src_reg)) {
3502                 print_verifier_state(env, state);
3503                 verbose(env, "verifier internal error: no src_reg\n");
3504                 return -EINVAL;
3505         }
3506         return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
3507 }
3508 
3509 /* check validity of 32-bit and 64-bit arithmetic operations */
3510 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
3511 {
3512         struct bpf_reg_state *regs = cur_regs(env);
3513         u8 opcode = BPF_OP(insn->code);
3514         int err;
3515 
3516         if (opcode == BPF_END || opcode == BPF_NEG) {
3517                 if (opcode == BPF_NEG) {
3518                         if (BPF_SRC(insn->code) != 0 ||
3519                             insn->src_reg != BPF_REG_0 ||
3520                             insn->off != 0 || insn->imm != 0) {
3521                                 verbose(env, "BPF_NEG uses reserved fields\n");
3522                                 return -EINVAL;
3523                         }
3524                 } else {
3525                         if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
3526                             (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
3527                             BPF_CLASS(insn->code) == BPF_ALU64) {
3528                                 verbose(env, "BPF_END uses reserved fields\n");
3529                                 return -EINVAL;
3530                         }
3531                 }
3532 
3533                 /* check src operand */
3534                 err = check_reg_arg(env, insn->dst_reg, SRC_OP);
3535                 if (err)
3536                         return err;
3537 
3538                 if (is_pointer_value(env, insn->dst_reg)) {
3539                         verbose(env, "R%d pointer arithmetic prohibited\n",
3540                                 insn->dst_reg);
3541                         return -EACCES;
3542                 }
3543 
3544                 /* check dest operand */
3545                 err = check_reg_arg(env, insn->dst_reg, DST_OP);
3546                 if (err)
3547                         return err;
3548 
3549         } else if (opcode == BPF_MOV) {
3550 
3551                 if (BPF_SRC(insn->code) == BPF_X) {
3552                         if (insn->imm != 0 || insn->off != 0) {
3553                                 verbose(env, "BPF_MOV uses reserved fields\n");
3554                                 return -EINVAL;
3555                         }
3556 
3557                         /* check src operand */
3558                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
3559                         if (err)
3560                                 return err;
3561                 } else {
3562                         if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
3563                                 verbose(env, "BPF_MOV uses reserved fields\n");
3564                                 return -EINVAL;
3565                         }
3566                 }
3567 
3568                 /* check dest operand, mark as required later */
3569                 err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
3570                 if (err)
3571                         return err;
3572 
3573                 if (BPF_SRC(insn->code) == BPF_X) {
3574                         if (BPF_CLASS(insn->code) == BPF_ALU64) {
3575                                 /* case: R1 = R2
3576                                  * copy register state to dest reg
3577                                  */
3578                                 regs[insn->dst_reg] = regs[insn->src_reg];
3579                                 regs[insn->dst_reg].live |= REG_LIVE_WRITTEN;
3580                         } else {
3581                                 /* R1 = (u32) R2 */
3582                                 if (is_pointer_value(env, insn->src_reg)) {
3583                                         verbose(env,
3584                                                 "R%d partial copy of pointer\n",
3585                                                 insn->src_reg);
3586                                         return -EACCES;
3587                                 }
3588                                 mark_reg_unknown(env, regs, insn->dst_reg);
3589                                 coerce_reg_to_size(&regs[insn->dst_reg], 4);
3590                         }
3591                 } else {
3592                         /* case: R = imm
3593                          * remember the value we stored into this reg
3594                          */
3595                         /* clear any state __mark_reg_known doesn't set */
3596                         mark_reg_unknown(env, regs, insn->dst_reg);
3597                         regs[insn->dst_reg].type = SCALAR_VALUE;
3598                         if (BPF_CLASS(insn->code) == BPF_ALU64) {
3599                                 __mark_reg_known(regs + insn->dst_reg,
3600                                                  insn->imm);
3601                         } else {
3602                                 __mark_reg_known(regs + insn->dst_reg,
3603                                                  (u32)insn->imm);
3604                         }
3605                 }
3606 
3607         } else if (opcode > BPF_END) {
3608                 verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
3609                 return -EINVAL;
3610 
3611         } else {        /* all other ALU ops: and, sub, xor, add, ... */
3612 
3613                 if (BPF_SRC(insn->code) == BPF_X) {
3614                         if (insn->imm != 0 || insn->off != 0) {
3615                                 verbose(env, "BPF_ALU uses reserved fields\n");
3616                                 return -EINVAL;
3617                         }
3618                         /* check src1 operand */
3619                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
3620                         if (err)
3621                                 return err;
3622                 } else {
3623                         if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
3624                                 verbose(env, "BPF_ALU uses reserved fields\n");
3625                                 return -EINVAL;
3626                         }
3627                 }
3628 
3629                 /* check src2 operand */
3630                 err = check_reg_arg(env, insn->dst_reg, SRC_OP);
3631                 if (err)
3632                         return err;
3633 
3634                 if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
3635                     BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
3636                         verbose(env, "div by zero\n");
3637                         return -EINVAL;
3638                 }
3639 
3640                 if (opcode == BPF_ARSH && BPF_CLASS(insn->code) != BPF_ALU64) {
3641                         verbose(env, "BPF_ARSH not supported for 32 bit ALU\n");
3642                         return -EINVAL;
3643                 }
3644 
3645                 if ((opcode == BPF_LSH || opcode == BPF_RSH ||
3646                      opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
3647                         int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
3648 
3649                         if (insn->imm < 0 || insn->imm >= size) {
3650                                 verbose(env, "invalid shift %d\n", insn->imm);
3651                                 return -EINVAL;
3652                         }
3653                 }
3654 
3655                 /* check dest operand */
3656                 err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
3657                 if (err)
3658                         return err;
3659 
3660                 return adjust_reg_min_max_vals(env, insn);
3661         }
3662 
3663         return 0;
3664 }
3665 
3666 static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
3667                                    struct bpf_reg_state *dst_reg,
3668                                    enum bpf_reg_type type,
3669                                    bool range_right_open)
3670 {
3671         struct bpf_func_state *state = vstate->frame[vstate->curframe];
3672         struct bpf_reg_state *regs = state->regs, *reg;
3673         u16 new_range;
3674         int i, j;
3675 
3676         if (dst_reg->off < 0 ||
3677             (dst_reg->off == 0 && range_right_open))
3678                 /* This doesn't give us any range */
3679                 return;
3680 
3681         if (dst_reg->umax_value > MAX_PACKET_OFF ||
3682             dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF)
3683                 /* Risk of overflow.  For instance, ptr + (1<<63) may be less
3684                  * than pkt_end, but that's because it's also less than pkt.
3685                  */
3686                 return;
3687 
3688         new_range = dst_reg->off;
3689         if (range_right_open)
3690                 new_range--;
3691 
3692         /* Examples for register markings:
3693          *
3694          * pkt_data in dst register:
3695          *
3696          *   r2 = r3;
3697          *   r2 += 8;
3698          *   if (r2 > pkt_end) goto <handle exception>
3699          *   <access okay>
3700          *
3701          *   r2 = r3;
3702          *   r2 += 8;
3703          *   if (r2 < pkt_end) goto <access okay>
3704          *   <handle exception>
3705          *
3706          *   Where:
3707          *     r2 == dst_reg, pkt_end == src_reg
3708          *     r2=pkt(id=n,off=8,r=0)
3709          *     r3=pkt(id=n,off=0,r=0)
3710          *
3711          * pkt_data in src register:
3712          *
3713          *   r2 = r3;
3714          *   r2 += 8;
3715          *   if (pkt_end >= r2) goto <access okay>
3716          *   <handle exception>
3717          *
3718          *   r2 = r3;
3719          *   r2 += 8;
3720          *   if (pkt_end <= r2) goto <handle exception>
3721          *   <access okay>
3722          *
3723          *   Where:
3724          *     pkt_end == dst_reg, r2 == src_reg
3725          *     r2=pkt(id=n,off=8,r=0)
3726          *     r3=pkt(id=n,off=0,r=0)
3727          *
3728          * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
3729          * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
3730          * and [r3, r3 + 8-1) respectively is safe to access depending on
3731          * the check.
3732          */
3733 
3734         /* If our ids match, then we must have the same max_value.  And we
3735          * don't care about the other reg's fixed offset, since if it's too big
3736          * the range won't allow anything.
3737          * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
3738          */
3739         for (i = 0; i < MAX_BPF_REG; i++)
3740                 if (regs[i].type == type && regs[i].id == dst_reg->id)
3741                         /* keep the maximum range already checked */
3742                         regs[i].range = max(regs[i].range, new_range);
3743 
3744         for (j = 0; j <= vstate->curframe; j++) {
3745                 state = vstate->frame[j];
3746                 bpf_for_each_spilled_reg(i, state, reg) {
3747                         if (!reg)
3748                                 continue;
3749                         if (reg->type == type && reg->id == dst_reg->id)
3750                                 reg->range = max(reg->range, new_range);
3751                 }
3752         }
3753 }
3754 
3755 /* compute branch direction of the expression "if (reg opcode val) goto target;"
3756  * and return:
3757  *  1 - branch will be taken and "goto target" will be executed
3758  *  0 - branch will not be taken and fall-through to next insn
3759  * -1 - unknown. Example: "if (reg < 5)" is unknown when register value range [0,10]
3760  */
3761 static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode)
3762 {
3763         if (__is_pointer_value(false, reg))
3764                 return -1;
3765 
3766         switch (opcode) {
3767         case BPF_JEQ:
3768                 if (tnum_is_const(reg->var_off))
3769                         return !!tnum_equals_const(reg->var_off, val);
3770                 break;
3771         case BPF_JNE:
3772                 if (tnum_is_const(reg->var_off))
3773                         return !tnum_equals_const(reg->var_off, val);
3774                 break;
3775         case BPF_JGT:
3776                 if (reg->umin_value > val)
3777                         return 1;
3778                 else if (reg->umax_value <= val)
3779                         return 0;
3780                 break;
3781         case BPF_JSGT:
3782                 if (reg->smin_value > (s64)val)
3783                         return 1;
3784                 else if (reg->smax_value < (s64)val)
3785                         return 0;
3786                 break;
3787         case BPF_JLT:
3788                 if (reg->umax_value < val)
3789                         return 1;
3790                 else if (reg->umin_value >= val)
3791                         return 0;
3792                 break;
3793         case BPF_JSLT:
3794                 if (reg->smax_value < (s64)val)
3795                         return 1;
3796                 else if (reg->smin_value >= (s64)val)
3797                         return 0;
3798                 break;
3799         case BPF_JGE:
3800                 if (reg->umin_value >= val)
3801                         return 1;
3802                 else if (reg->umax_value < val)
3803                         return 0;
3804                 break;
3805         case BPF_JSGE:
3806                 if (reg->smin_value >= (s64)val)
3807                         return 1;
3808                 else if (reg->smax_value < (s64)val)
3809                         return 0;
3810                 break;
3811         case BPF_JLE:
3812                 if (reg->umax_value <= val)
3813                         return 1;
3814                 else if (reg->umin_value > val)
3815                         return 0;
3816                 break;
3817         case BPF_JSLE:
3818                 if (reg->smax_value <= (s64)val)
3819                         return 1;
3820                 else if (reg->smin_value > (s64)val)
3821                         return 0;
3822                 break;
3823         }
3824 
3825         return -1;
3826 }
3827 
3828 /* Adjusts the register min/max values in the case that the dst_reg is the
3829  * variable register that we are working on, and src_reg is a constant or we're
3830  * simply doing a BPF_K check.
3831  * In JEQ/JNE cases we also adjust the var_off values.
3832  */
3833 static void reg_set_min_max(struct bpf_reg_state *true_reg,
3834                             struct bpf_reg_state *false_reg, u64 val,
3835                             u8 opcode)
3836 {
3837         /* If the dst_reg is a pointer, we can't learn anything about its
3838          * variable offset from the compare (unless src_reg were a pointer into
3839          * the same object, but we don't bother with that.
3840          * Since false_reg and true_reg have the same type by construction, we
3841          * only need to check one of them for pointerness.
3842          */
3843         if (__is_pointer_value(false, false_reg))
3844                 return;
3845 
3846         switch (opcode) {
3847         case BPF_JEQ:
3848                 /* If this is false then we know nothing Jon Snow, but if it is
3849                  * true then we know for sure.
3850                  */
3851                 __mark_reg_known(true_reg, val);
3852                 break;
3853         case BPF_JNE:
3854                 /* If this is true we know nothing Jon Snow, but if it is false
3855                  * we know the value for sure;
3856                  */
3857                 __mark_reg_known(false_reg, val);
3858                 break;
3859         case BPF_JGT:
3860                 false_reg->umax_value = min(false_reg->umax_value, val);
3861                 true_reg->umin_value = max(true_reg->umin_value, val + 1);
3862                 break;
3863         case BPF_JSGT:
3864                 false_reg->smax_value = min_t(s64, false_reg->smax_value, val);
3865                 true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1);
3866                 break;
3867         case BPF_JLT:
3868                 false_reg->umin_value = max(false_reg->umin_value, val);
3869                 true_reg->umax_value = min(true_reg->umax_value, val - 1);
3870                 break;
3871         case BPF_JSLT:
3872                 false_reg->smin_value = max_t(s64, false_reg->smin_value, val);
3873                 true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1);
3874                 break;
3875         case BPF_JGE:
3876                 false_reg->umax_value = min(false_reg->umax_value, val - 1);
3877                 true_reg->umin_value = max(true_reg->umin_value, val);
3878                 break;
3879         case BPF_JSGE:
3880                 false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1);
3881                 true_reg->smin_value = max_t(s64, true_reg->smin_value, val);
3882                 break;
3883         case BPF_JLE:
3884                 false_reg->umin_value = max(false_reg->umin_value, val + 1);
3885                 true_reg->umax_value = min(true_reg->umax_value, val);
3886                 break;
3887         case BPF_JSLE:
3888                 false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1);
3889                 true_reg->smax_value = min_t(s64, true_reg->smax_value, val);
3890                 break;
3891         default:
3892                 break;
3893         }
3894 
3895         __reg_deduce_bounds(false_reg);
3896         __reg_deduce_bounds(true_reg);
3897         /* We might have learned some bits from the bounds. */
3898         __reg_bound_offset(false_reg);
3899         __reg_bound_offset(true_reg);
3900         /* Intersecting with the old var_off might have improved our bounds
3901          * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
3902          * then new var_off is (0; 0x7f...fc) which improves our umax.
3903          */
3904         __update_reg_bounds(false_reg);
3905         __update_reg_bounds(true_reg);
3906 }
3907 
3908 /* Same as above, but for the case that dst_reg holds a constant and src_reg is
3909  * the variable reg.
3910  */
3911 static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
3912                                 struct bpf_reg_state *false_reg, u64 val,
3913                                 u8 opcode)
3914 {
3915         if (__is_pointer_value(false, false_reg))
3916                 return;
3917 
3918         switch (opcode) {
3919         case BPF_JEQ:
3920                 /* If this is false then we know nothing Jon Snow, but if it is
3921                  * true then we know for sure.
3922                  */
3923                 __mark_reg_known(true_reg, val);
3924                 break;
3925         case BPF_JNE:
3926                 /* If this is true we know nothing Jon Snow, but if it is false
3927                  * we know the value for sure;
3928                  */
3929                 __mark_reg_known(false_reg, val);
3930                 break;
3931         case BPF_JGT:
3932                 true_reg->umax_value = min(true_reg->umax_value, val - 1);
3933                 false_reg->umin_value = max(false_reg->umin_value, val);
3934                 break;
3935         case BPF_JSGT:
3936                 true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1);
3937                 false_reg->smin_value = max_t(s64, false_reg->smin_value, val);
3938                 break;
3939         case BPF_JLT:
3940                 true_reg->umin_value = max(true_reg->umin_value, val + 1);
3941                 false_reg->umax_value = min(false_reg->umax_value, val);
3942                 break;
3943         case BPF_JSLT:
3944                 true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1);
3945                 false_reg->smax_value = min_t(s64, false_reg->smax_value, val);
3946                 break;
3947         case BPF_JGE:
3948                 true_reg->umax_value = min(true_reg->umax_value, val);
3949                 false_reg->umin_value = max(false_reg->umin_value, val + 1);
3950                 break;
3951         case BPF_JSGE:
3952                 true_reg->smax_value = min_t(s64, true_reg->smax_value, val);
3953                 false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1);
3954                 break;
3955         case BPF_JLE:
3956                 true_reg->umin_value = max(true_reg->umin_value, val);
3957                 false_reg->umax_value = min(false_reg->umax_value, val - 1);
3958                 break;
3959         case BPF_JSLE:
3960                 true_reg->smin_value = max_t(s64, true_reg->smin_value, val);
3961                 false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1);
3962                 break;
3963         default:
3964                 break;
3965         }
3966 
3967         __reg_deduce_bounds(false_reg);
3968         __reg_deduce_bounds(true_reg);
3969         /* We might have learned some bits from the bounds. */
3970         __reg_bound_offset(false_reg);
3971         __reg_bound_offset(true_reg);
3972         /* Intersecting with the old var_off might have improved our bounds
3973          * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
3974          * then new var_off is (0; 0x7f...fc) which improves our umax.
3975          */
3976         __update_reg_bounds(false_reg);
3977         __update_reg_bounds(true_reg);
3978 }
3979 
3980 /* Regs are known to be equal, so intersect their min/max/var_off */
3981 static void __reg_combine_min_max(struct bpf_reg_state *src_reg,
3982                                   struct bpf_reg_state *dst_reg)
3983 {
3984         src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value,
3985                                                         dst_reg->umin_value);
3986         src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value,
3987                                                         dst_reg->umax_value);
3988         src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value,
3989                                                         dst_reg->smin_value);
3990         src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value,
3991                                                         dst_reg->smax_value);
3992         src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off,
3993                                                              dst_reg->var_off);
3994         /* We might have learned new bounds from the var_off. */
3995         __update_reg_bounds(src_reg);
3996         __update_reg_bounds(dst_reg);
3997         /* We might have learned something about the sign bit. */
3998         __reg_deduce_bounds(src_reg);
3999         __reg_deduce_bounds(dst_reg);
4000         /* We might have learned some bits from the bounds. */
4001         __reg_bound_offset(src_reg);
4002         __reg_bound_offset(dst_reg);
4003         /* Intersecting with the old var_off might have improved our bounds
4004          * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
4005          * then new var_off is (0; 0x7f...fc) which improves our umax.
4006          */
4007         __update_reg_bounds(src_reg);
4008         __update_reg_bounds(dst_reg);
4009 }
4010 
4011 static void reg_combine_min_max(struct bpf_reg_state *true_src,
4012                                 struct bpf_reg_state *true_dst,
4013                                 struct bpf_reg_state *false_src,
4014                                 struct bpf_reg_state *false_dst,
4015                                 u8 opcode)
4016 {
4017         switch (opcode) {
4018         case BPF_JEQ:
4019                 __reg_combine_min_max(true_src, true_dst);
4020                 break;
4021         case BPF_JNE:
4022                 __reg_combine_min_max(false_src, false_dst);
4023                 break;
4024         }
4025 }
4026 
4027 static void mark_ptr_or_null_reg(struct bpf_func_state *state,
4028                                  struct bpf_reg_state *reg, u32 id,
4029                                  bool is_null)
4030 {
4031         if (reg_type_may_be_null(reg->type) && reg->id == id) {
4032                 /* Old offset (both fixed and variable parts) should
4033                  * have been known-zero, because we don't allow pointer
4034                  * arithmetic on pointers that might be NULL.
4035                  */
4036                 if (WARN_ON_ONCE(reg->smin_value || reg->smax_value ||
4037                                  !tnum_equals_const(reg->var_off, 0) ||
4038                                  reg->off)) {
4039                         __mark_reg_known_zero(reg);
4040                         reg->off = 0;
4041                 }
4042                 if (is_null) {
4043                         reg->type = SCALAR_VALUE;
4044                 } else if (reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
4045                         if (reg->map_ptr->inner_map_meta) {
4046                                 reg->type = CONST_PTR_TO_MAP;
4047                                 reg->map_ptr = reg->map_ptr->inner_map_meta;
4048                         } else {
4049                                 reg->type = PTR_TO_MAP_VALUE;
4050                         }
4051                 } else if (reg->type == PTR_TO_SOCKET_OR_NULL) {
4052                         reg->type = PTR_TO_SOCKET;
4053                 }
4054                 if (is_null || !reg_is_refcounted(reg)) {
4055                         /* We don't need id from this point onwards anymore,
4056                          * thus we should better reset it, so that state
4057                          * pruning has chances to take effect.
4058                          */
4059                         reg->id = 0;
4060                 }
4061         }
4062 }
4063 
4064 /* The logic is similar to find_good_pkt_pointers(), both could eventually
4065  * be folded together at some point.
4066  */
4067 static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
4068                                   bool is_null)
4069 {
4070         struct bpf_func_state *state = vstate->frame[vstate->curframe];
4071         struct bpf_reg_state *reg, *regs = state->regs;
4072         u32 id = regs[regno].id;
4073         int i, j;
4074 
4075         if (reg_is_refcounted_or_null(&regs[regno]) && is_null)
4076                 __release_reference_state(state, id);
4077 
4078         for (i = 0; i < MAX_BPF_REG; i++)
4079                 mark_ptr_or_null_reg(state, &regs[i], id, is_null);
4080 
4081         for (j = 0; j <= vstate->curframe; j++) {
4082                 state = vstate->frame[j];
4083                 bpf_for_each_spilled_reg(i, state, reg) {
4084                         if (!reg)
4085                                 continue;
4086                         mark_ptr_or_null_reg(state, reg, id, is_null);
4087                 }
4088         }
4089 }
4090 
4091 static bool try_match_pkt_pointers(const struct bpf_insn *insn,
4092                                    struct bpf_reg_state *dst_reg,
4093                                    struct bpf_reg_state *src_reg,
4094                                    struct bpf_verifier_state *this_branch,
4095                                    struct bpf_verifier_state *other_branch)
4096 {
4097         if (BPF_SRC(insn->code) != BPF_X)
4098                 return false;
4099 
4100         switch (BPF_OP(insn->code)) {
4101         case BPF_JGT:
4102                 if ((dst_reg->type == PTR_TO_PACKET &&
4103                      src_reg->type == PTR_TO_PACKET_END) ||
4104                     (dst_reg->type == PTR_TO_PACKET_META &&
4105                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
4106                         /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
4107                         find_good_pkt_pointers(this_branch, dst_reg,
4108                                                dst_reg->type, false);
4109                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
4110                             src_reg->type == PTR_TO_PACKET) ||
4111                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
4112                             src_reg->type == PTR_TO_PACKET_META)) {
4113                         /* pkt_end > pkt_data', pkt_data > pkt_meta' */
4114                         find_good_pkt_pointers(other_branch, src_reg,
4115                                                src_reg->type, true);
4116                 } else {
4117                         return false;
4118                 }
4119                 break;
4120         case BPF_JLT:
4121                 if ((dst_reg->type == PTR_TO_PACKET &&
4122                      src_reg->type == PTR_TO_PACKET_END) ||
4123                     (dst_reg->type == PTR_TO_PACKET_META &&
4124                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
4125                         /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
4126                         find_good_pkt_pointers(other_branch, dst_reg,
4127                                                dst_reg->type, true);
4128                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
4129                             src_reg->type == PTR_TO_PACKET) ||
4130                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
4131                             src_reg->type == PTR_TO_PACKET_META)) {
4132                         /* pkt_end < pkt_data', pkt_data > pkt_meta' */
4133                         find_good_pkt_pointers(this_branch, src_reg,
4134                                                src_reg->type, false);
4135                 } else {
4136                         return false;
4137                 }
4138                 break;
4139         case BPF_JGE:
4140                 if ((dst_reg->type == PTR_TO_PACKET &&
4141                      src_reg->type == PTR_TO_PACKET_END) ||
4142                     (dst_reg->type == PTR_TO_PACKET_META &&
4143                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
4144                         /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
4145                         find_good_pkt_pointers(this_branch, dst_reg,
4146                                                dst_reg->type, true);
4147                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
4148                             src_reg->type == PTR_TO_PACKET) ||
4149                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
4150                             src_reg->type == PTR_TO_PACKET_META)) {
4151                         /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
4152                         find_good_pkt_pointers(other_branch, src_reg,
4153                                                src_reg->type, false);
4154                 } else {
4155                         return false;
4156                 }
4157                 break;
4158         case BPF_JLE:
4159                 if ((dst_reg->type == PTR_TO_PACKET &&
4160                      src_reg->type == PTR_TO_PACKET_END) ||
4161                     (dst_reg->type == PTR_TO_PACKET_META &&
4162                      reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
4163                         /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
4164                         find_good_pkt_pointers(other_branch, dst_reg,
4165                                                dst_reg->type, false);
4166                 } else if ((dst_reg->type == PTR_TO_PACKET_END &&
4167                             src_reg->type == PTR_TO_PACKET) ||
4168                            (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
4169                             src_reg->type == PTR_TO_PACKET_META)) {
4170                         /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
4171                         find_good_pkt_pointers(this_branch, src_reg,
4172                                                src_reg->type, true);
4173                 } else {
4174                         return false;
4175                 }
4176                 break;
4177         default:
4178                 return false;
4179         }
4180 
4181         return true;
4182 }
4183 
4184 static int check_cond_jmp_op(struct bpf_verifier_env *env,
4185                              struct bpf_insn *insn, int *insn_idx)
4186 {
4187         struct bpf_verifier_state *this_branch = env->cur_state;
4188         struct bpf_verifier_state *other_branch;
4189         struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
4190         struct bpf_reg_state *dst_reg, *other_branch_regs;
4191         u8 opcode = BPF_OP(insn->code);
4192         int err;
4193 
4194         if (opcode > BPF_JSLE) {
4195                 verbose(env, "invalid BPF_JMP opcode %x\n", opcode);
4196                 return -EINVAL;
4197         }
4198 
4199         if (BPF_SRC(insn->code) == BPF_X) {
4200                 if (insn->imm != 0) {
4201                         verbose(env, "BPF_JMP uses reserved fields\n");
4202                         return -EINVAL;
4203                 }
4204 
4205                 /* check src1 operand */
4206                 err = check_reg_arg(env, insn->src_reg, SRC_OP);
4207                 if (err)
4208                         return err;
4209 
4210                 if (is_pointer_value(env, insn->src_reg)) {
4211                         verbose(env, "R%d pointer comparison prohibited\n",
4212                                 insn->src_reg);
4213                         return -EACCES;
4214                 }
4215         } else {
4216                 if (insn->src_reg != BPF_REG_0) {
4217                         verbose(env, "BPF_JMP uses reserved fields\n");
4218                         return -EINVAL;
4219                 }
4220         }
4221 
4222         /* check src2 operand */
4223         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
4224         if (err)
4225                 return err;
4226 
4227         dst_reg = &regs[insn->dst_reg];
4228 
4229         if (BPF_SRC(insn->code) == BPF_K) {
4230                 int pred = is_branch_taken(dst_reg, insn->imm, opcode);
4231 
4232                 if (pred == 1) {
4233                          /* only follow the goto, ignore fall-through */
4234                         *insn_idx += insn->off;
4235                         return 0;
4236                 } else if (pred == 0) {
4237                         /* only follow fall-through branch, since
4238                          * that's where the program will go
4239                          */
4240                         return 0;
4241                 }
4242         }
4243 
4244         other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
4245         if (!other_branch)
4246                 return -EFAULT;
4247         other_branch_regs = other_branch->frame[other_branch->curframe]->regs;
4248 
4249         /* detect if we are comparing against a constant value so we can adjust
4250          * our min/max values for our dst register.
4251          * this is only legit if both are scalars (or pointers to the same
4252          * object, I suppose, but we don't support that right now), because
4253          * otherwise the different base pointers mean the offsets aren't
4254          * comparable.
4255          */
4256         if (BPF_SRC(insn->code) == BPF_X) {
4257                 if (dst_reg->type == SCALAR_VALUE &&
4258                     regs[insn->src_reg].type == SCALAR_VALUE) {
4259                         if (tnum_is_const(regs[insn->src_reg].var_off))
4260                                 reg_set_min_max(&other_branch_regs[insn->dst_reg],
4261                                                 dst_reg, regs[insn->src_reg].var_off.value,
4262                                                 opcode);
4263                         else if (tnum_is_const(dst_reg->var_off))
4264                                 reg_set_min_max_inv(&other_branch_regs[insn->src_reg],
4265                                                     &regs[insn->src_reg],
4266                                                     dst_reg->var_off.value, opcode);
4267                         else if (opcode == BPF_JEQ || opcode == BPF_JNE)
4268                                 /* Comparing for equality, we can combine knowledge */
4269                                 reg_combine_min_max(&other_branch_regs[insn->src_reg],
4270                                                     &other_branch_regs[insn->dst_reg],
4271                                                     &regs[insn->src_reg],
4272                                                     &regs[insn->dst_reg], opcode);
4273                 }
4274         } else if (dst_reg->type == SCALAR_VALUE) {
4275                 reg_set_min_max(&other_branch_regs[insn->dst_reg],
4276                                         dst_reg, insn->imm, opcode);
4277         }
4278 
4279         /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
4280         if (BPF_SRC(insn->code) == BPF_K &&
4281             insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
4282             reg_type_may_be_null(dst_reg->type)) {
4283                 /* Mark all identical registers in each branch as either
4284                  * safe or unknown depending R == 0 or R != 0 conditional.
4285                  */
4286                 mark_ptr_or_null_regs(this_branch, insn->dst_reg,
4287                                       opcode == BPF_JNE);
4288                 mark_ptr_or_null_regs(other_branch, insn->dst_reg,
4289                                       opcode == BPF_JEQ);
4290         } else if (!try_match_pkt_pointers(insn, dst_reg, &regs[insn->src_reg],
4291                                            this_branch, other_branch) &&
4292                    is_pointer_value(env, insn->dst_reg)) {
4293                 verbose(env, "R%d pointer comparison prohibited\n",
4294                         insn->dst_reg);
4295                 return -EACCES;
4296         }
4297         if (env->log.level)
4298                 print_verifier_state(env, this_branch->frame[this_branch->curframe]);
4299         return 0;
4300 }
4301 
4302 /* return the map pointer stored inside BPF_LD_IMM64 instruction */
4303 static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
4304 {
4305         u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
4306 
4307         return (struct bpf_map *) (unsigned long) imm64;
4308 }
4309 
4310 /* verify BPF_LD_IMM64 instruction */
4311 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
4312 {
4313         struct bpf_reg_state *regs = cur_regs(env);
4314         int err;
4315 
4316         if (BPF_SIZE(insn->code) != BPF_DW) {
4317                 verbose(env, "invalid BPF_LD_IMM insn\n");
4318                 return -EINVAL;
4319         }
4320         if (insn->off != 0) {
4321                 verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
4322                 return -EINVAL;
4323         }
4324 
4325         err = check_reg_arg(env, insn->dst_reg, DST_OP);
4326         if (err)
4327                 return err;
4328 
4329         if (insn->src_reg == 0) {
4330                 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
4331 
4332                 regs[insn->dst_reg].type = SCALAR_VALUE;
4333                 __mark_reg_known(&regs[insn->dst_reg], imm);
4334                 return 0;
4335         }
4336 
4337         /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
4338         BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
4339 
4340         regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
4341         regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
4342         return 0;
4343 }
4344 
4345 static bool may_access_skb(enum bpf_prog_type type)
4346 {
4347         switch (type) {
4348         case BPF_PROG_TYPE_SOCKET_FILTER:
4349         case BPF_PROG_TYPE_SCHED_CLS:
4350         case BPF_PROG_TYPE_SCHED_ACT:
4351                 return true;
4352         default:
4353                 return false;
4354         }
4355 }
4356 
4357 /* verify safety of LD_ABS|LD_IND instructions:
4358  * - they can only appear in the programs where ctx == skb
4359  * - since they are wrappers of function calls, they scratch R1-R5 registers,
4360  *   preserve R6-R9, and store return value into R0
4361  *
4362  * Implicit input:
4363  *   ctx == skb == R6 == CTX
4364  *
4365  * Explicit input:
4366  *   SRC == any register
4367  *   IMM == 32-bit immediate
4368  *
4369  * Output:
4370  *   R0 - 8/16/32-bit skb data converted to cpu endianness
4371  */
4372 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
4373 {
4374         struct bpf_reg_state *regs = cur_regs(env);
4375         u8 mode = BPF_MODE(insn->code);
4376         int i, err;
4377 
4378         if (!may_access_skb(env->prog->type)) {
4379                 verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
4380                 return -EINVAL;
4381         }
4382 
4383         if (!env->ops->gen_ld_abs) {
4384                 verbose(env, "bpf verifier is misconfigured\n");
4385                 return -EINVAL;
4386         }
4387 
4388         if (env->subprog_cnt > 1) {
4389                 /* when program has LD_ABS insn JITs and interpreter assume
4390                  * that r1 == ctx == skb which is not the case for callees
4391                  * that can have arbitrary arguments. It's problematic
4392                  * for main prog as well since JITs would need to analyze
4393                  * all functions in order to make proper register save/restore
4394                  * decisions in the main prog. Hence disallow LD_ABS with calls
4395                  */
4396                 verbose(env, "BPF_LD_[ABS|IND] instructions cannot be mixed with bpf-to-bpf calls\n");
4397                 return -EINVAL;
4398         }
4399 
4400         if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
4401             BPF_SIZE(insn->code) == BPF_DW ||
4402             (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
4403                 verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
4404                 return -EINVAL;
4405         }
4406 
4407         /* check whether implicit source operand (register R6) is readable */
4408         err = check_reg_arg(env, BPF_REG_6, SRC_OP);
4409         if (err)
4410                 return err;
4411 
4412         /* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
4413          * gen_ld_abs() may terminate the program at runtime, leading to
4414          * reference leak.
4415          */
4416         err = check_reference_leak(env);
4417         if (err) {
4418                 verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n");
4419                 return err;
4420         }
4421 
4422         if (regs[BPF_REG_6].type != PTR_TO_CTX) {
4423                 verbose(env,
4424                         "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
4425                 return -EINVAL;
4426         }
4427 
4428         if (mode == BPF_IND) {
4429                 /* check explicit source operand */
4430                 err = check_reg_arg(env, insn->src_reg, SRC_OP);
4431                 if (err)
4432                         return err;
4433         }
4434 
4435         /* reset caller saved regs to unreadable */
4436         for (i = 0; i < CALLER_SAVED_REGS; i++) {
4437                 mark_reg_not_init(env, regs, caller_saved[i]);
4438                 check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
4439         }
4440 
4441         /* mark destination R0 register as readable, since it contains
4442          * the value fetched from the packet.
4443          * Already marked as written above.
4444          */
4445         mark_reg_unknown(env, regs, BPF_REG_0);
4446         return 0;
4447 }
4448 
4449 static int check_return_code(struct bpf_verifier_env *env)
4450 {
4451         struct bpf_reg_state *reg;
4452         struct tnum range = tnum_range(0, 1);
4453 
4454         switch (env->prog->type) {
4455         case BPF_PROG_TYPE_CGROUP_SKB:
4456         case BPF_PROG_TYPE_CGROUP_SOCK:
4457         case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
4458         case BPF_PROG_TYPE_SOCK_OPS:
4459         case BPF_PROG_TYPE_CGROUP_DEVICE:
4460                 break;
4461         default:
4462                 return 0;
4463         }
4464 
4465         reg = cur_regs(env) + BPF_REG_0;
4466         if (reg->type != SCALAR_VALUE) {
4467                 verbose(env, "At program exit the register R0 is not a known value (%s)\n",
4468                         reg_type_str[reg->type]);
4469                 return -EINVAL;
4470         }
4471 
4472         if (!tnum_in(range, reg->var_off)) {
4473                 verbose(env, "At program exit the register R0 ");
4474                 if (!tnum_is_unknown(reg->var_off)) {
4475                         char tn_buf[48];
4476 
4477                         tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
4478                         verbose(env, "has value %s", tn_buf);
4479                 } else {
4480                         verbose(env, "has unknown scalar value");
4481                 }
4482                 verbose(env, " should have been 0 or 1\n");
4483                 return -EINVAL;
4484         }
4485         return 0;
4486 }
4487 
4488 /* non-recursive DFS pseudo code
4489  * 1  procedure DFS-iterative(G,v):
4490  * 2      label v as discovered
4491  * 3      let S be a stack
4492  * 4      S.push(v)
4493  * 5      while S is not empty
4494  * 6            t <- S.pop()
4495  * 7            if t is what we're looking for:
4496  * 8                return t
4497  * 9            for all edges e in G.adjacentEdges(t) do
4498  * 10               if edge e is already labelled
4499  * 11                   continue with the next edge
4500  * 12               w <- G.adjacentVertex(t,e)
4501  * 13               if vertex w is not discovered and not explored
4502  * 14                   label e as tree-edge
4503  * 15                   label w as discovered
4504  * 16                   S.push(w)
4505  * 17                   continue at 5
4506  * 18               else if vertex w is discovered
4507  * 19                   label e as back-edge
4508  * 20               else
4509  * 21                   // vertex w is explored
4510  * 22                   label e as forward- or cross-edge
4511  * 23           label t as explored
4512  * 24           S.pop()
4513  *
4514  * convention:
4515  * 0x10 - discovered
4516  * 0x11 - discovered and fall-through edge labelled
4517  * 0x12 - discovered and fall-through and branch edges labelled
4518  * 0x20 - explored
4519  */
4520 
4521 enum {
4522         DISCOVERED = 0x10,
4523         EXPLORED = 0x20,
4524         FALLTHROUGH = 1,
4525         BRANCH = 2,
4526 };
4527 
4528 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
4529 
4530 static int *insn_stack; /* stack of insns to process */
4531 static int cur_stack;   /* current stack index */
4532 static int *insn_state;
4533 
4534 /* t, w, e - match pseudo-code above:
4535  * t - index of current instruction
4536  * w - next instruction
4537  * e - edge
4538  */
4539 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
4540 {
4541         if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
4542                 return 0;
4543 
4544         if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
4545                 return 0;
4546 
4547         if (w < 0 || w >= env->prog->len) {
4548                 verbose(env, "jump out of range from insn %d to %d\n", t, w);
4549                 return -EINVAL;
4550         }
4551 
4552         if (e == BRANCH)
4553                 /* mark branch target for state pruning */
4554                 env->explored_states[w] = STATE_LIST_MARK;
4555 
4556         if (insn_state[w] == 0) {
4557                 /* tree-edge */
4558                 insn_state[t] = DISCOVERED | e;
4559                 insn_state[w] = DISCOVERED;
4560                 if (cur_stack >= env->prog->len)
4561                         return -E2BIG;
4562                 insn_stack[cur_stack++] = w;
4563                 return 1;
4564         } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
4565                 verbose(env, "back-edge from insn %d to %d\n", t, w);
4566                 return -EINVAL;
4567         } else if (insn_state[w] == EXPLORED) {
4568                 /* forward- or cross-edge */
4569                 insn_state[t] = DISCOVERED | e;
4570         } else {
4571                 verbose(env, "insn state internal bug\n");
4572                 return -EFAULT;
4573         }
4574         return 0;
4575 }
4576 
4577 /* non-recursive depth-first-search to detect loops in BPF program
4578  * loop == back-edge in directed graph
4579  */
4580 static int check_cfg(struct bpf_verifier_env *env)
4581 {
4582         struct bpf_insn *insns = env->prog->insnsi;
4583         int insn_cnt = env->prog->len;
4584         int ret = 0;
4585         int i, t;
4586 
4587         ret = check_subprogs(env);
4588         if (ret < 0)
4589                 return ret;
4590 
4591         insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
4592         if (!insn_state)
4593                 return -ENOMEM;
4594 
4595         insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
4596         if (!insn_stack) {
4597                 kfree(insn_state);
4598                 return -ENOMEM;
4599         }
4600 
4601         insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
4602         insn_stack[0] = 0; /* 0 is the first instruction */
4603         cur_stack = 1;
4604 
4605 peek_stack:
4606         if (cur_stack == 0)
4607                 goto check_state;
4608         t = insn_stack[cur_stack - 1];
4609 
4610         if (BPF_CLASS(insns[t].code) == BPF_JMP) {
4611                 u8 opcode = BPF_OP(insns[t].code);
4612 
4613                 if (opcode == BPF_EXIT) {
4614                         goto mark_explored;
4615                 } else if (opcode == BPF_CALL) {
4616                         ret = push_insn(t, t + 1, FALLTHROUGH, env);
4617                         if (ret == 1)
4618                                 goto peek_stack;
4619                         else if (ret < 0)
4620                                 goto err_free;
4621                         if (t + 1 < insn_cnt)
4622                                 env->explored_states[t + 1] = STATE_LIST_MARK;
4623                         if (insns[t].src_reg == BPF_PSEUDO_CALL) {
4624                                 env->explored_states[t] = STATE_LIST_MARK;
4625                                 ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env);
4626                                 if (ret == 1)
4627                                         goto peek_stack;
4628                                 else if (ret < 0)
4629                                         goto err_free;
4630                         }
4631                 } else if (opcode == BPF_JA) {
4632                         if (BPF_SRC(insns[t].code) != BPF_K) {
4633                                 ret = -EINVAL;
4634                                 goto err_free;
4635                         }
4636                         /* unconditional jump with single edge */
4637                         ret = push_insn(t, t + insns[t].off + 1,
4638                                         FALLTHROUGH, env);
4639                         if (ret == 1)
4640                                 goto peek_stack;
4641                         else if (ret < 0)
4642                                 goto err_free;
4643                         /* tell verifier to check for equivalent states
4644                          * after every call and jump
4645                          */
4646                         if (t + 1 < insn_cnt)
4647                                 env->explored_states[t + 1] = STATE_LIST_MARK;
4648                 } else {
4649                         /* conditional jump with two edges */
4650                         env->explored_states[t] = STATE_LIST_MARK;
4651                         ret = push_insn(t, t + 1, FALLTHROUGH, env);
4652                         if (ret == 1)
4653                                 goto peek_stack;
4654                         else if (ret < 0)
4655                                 goto err_free;
4656 
4657                         ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
4658                         if (ret == 1)
4659                                 goto peek_stack;
4660                         else if (ret < 0)
4661                                 goto err_free;
4662                 }
4663         } else {
4664                 /* all other non-branch instructions with single
4665                  * fall-through edge
4666                  */
4667                 ret = push_insn(t, t + 1, FALLTHROUGH, env);
4668                 if (ret == 1)
4669                         goto peek_stack;
4670                 else if (ret < 0)
4671                         goto err_free;
4672         }
4673 
4674 mark_explored:
4675         insn_state[t] = EXPLORED;
4676         if (cur_stack-- <= 0) {
4677                 verbose(env, "pop stack internal bug\n");
4678                 ret = -EFAULT;
4679                 goto err_free;
4680         }
4681         goto peek_stack;
4682 
4683 check_state:
4684         for (i = 0; i < insn_cnt; i++) {
4685                 if (insn_state[i] != EXPLORED) {
4686                         verbose(env, "unreachable insn %d\n", i);
4687                         ret = -EINVAL;
4688                         goto err_free;
4689                 }
4690         }
4691         ret = 0; /* cfg looks good */
4692 
4693 err_free:
4694         kfree(insn_state);
4695         kfree(insn_stack);
4696         return ret;
4697 }
4698 
4699 /* check %cur's range satisfies %old's */
4700 static bool range_within(struct bpf_reg_state *old,
4701                          struct bpf_reg_state *cur)
4702 {
4703         return old->umin_value <= cur->umin_value &&
4704                old->umax_value >= cur->umax_value &&
4705                old->smin_value <= cur->smin_value &&
4706                old->smax_value >= cur->smax_value;
4707 }
4708 
4709 /* Maximum number of register states that can exist at once */
4710 #define ID_MAP_SIZE     (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE)
4711 struct idpair {
4712         u32 old;
4713         u32 cur;
4714 };
4715 
4716 /* If in the old state two registers had the same id, then they need to have
4717  * the same id in the new state as well.  But that id could be different from
4718  * the old state, so we need to track the mapping from old to new ids.
4719  * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
4720  * regs with old id 5 must also have new id 9 for the new state to be safe.  But
4721  * regs with a different old id could still have new id 9, we don't care about
4722  * that.
4723  * So we look through our idmap to see if this old id has been seen before.  If
4724  * so, we require the new id to match; otherwise, we add the id pair to the map.
4725  */
4726 static bool check_ids(u32 old_id, u32 cur_id, struct idpair *idmap)
4727 {
4728         unsigned int i;
4729 
4730         for (i = 0; i < ID_MAP_SIZE; i++) {
4731                 if (!idmap[i].old) {
4732                         /* Reached an empty slot; haven't seen this id before */
4733                         idmap[i].old = old_id;
4734                         idmap[i].cur = cur_id;
4735                         return true;
4736                 }
4737                 if (idmap[i].old == old_id)
4738                         return idmap[i].cur == cur_id;
4739         }
4740         /* We ran out of idmap slots, which should be impossible */
4741         WARN_ON_ONCE(1);
4742         return false;
4743 }
4744 
4745 /* Returns true if (rold safe implies rcur safe) */
4746 static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
4747                     struct idpair *idmap)
4748 {
4749         bool equal;
4750 
4751         if (!(rold->live & REG_LIVE_READ))
4752                 /* explored state didn't use this */
4753                 return true;
4754 
4755         equal = memcmp(rold, rcur, offsetof(struct bpf_reg_state, parent)) == 0;
4756 
4757         if (rold->type == PTR_TO_STACK)
4758                 /* two stack pointers are equal only if they're pointing to
4759                  * the same stack frame, since fp-8 in foo != fp-8 in bar
4760                  */
4761                 return equal && rold->frameno == rcur->frameno;
4762 
4763         if (equal)
4764                 return true;
4765 
4766         if (rold->type == NOT_INIT)
4767                 /* explored state can't have used this */
4768                 return true;
4769         if (rcur->type == NOT_INIT)
4770                 return false;
4771         switch (rold->type) {
4772         case SCALAR_VALUE:
4773                 if (rcur->type == SCALAR_VALUE) {
4774                         /* new val must satisfy old val knowledge */
4775                         return range_within(rold, rcur) &&
4776                                tnum_in(rold->var_off, rcur->var_off);
4777                 } else {
4778                         /* We're trying to use a pointer in place of a scalar.
4779                          * Even if the scalar was unbounded, this could lead to
4780                          * pointer leaks because scalars are allowed to leak
4781                          * while pointers are not. We could make this safe in
4782                          * special cases if root is calling us, but it's
4783                          * probably not worth the hassle.
4784                          */
4785                         return false;
4786                 }
4787         case PTR_TO_MAP_VALUE:
4788                 /* If the new min/max/var_off satisfy the old ones and
4789                  * everything else matches, we are OK.
4790                  * We don't care about the 'id' value, because nothing
4791                  * uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL)
4792                  */
4793                 return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
4794                        range_within(rold, rcur) &&
4795                        tnum_in(rold->var_off, rcur->var_off);
4796         case PTR_TO_MAP_VALUE_OR_NULL:
4797                 /* a PTR_TO_MAP_VALUE could be safe to use as a
4798                  * PTR_TO_MAP_VALUE_OR_NULL into the same map.
4799                  * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
4800                  * checked, doing so could have affected others with the same
4801                  * id, and we can't check for that because we lost the id when
4802                  * we converted to a PTR_TO_MAP_VALUE.
4803                  */
4804                 if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL)
4805                         return false;
4806                 if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)))
4807                         return false;
4808                 /* Check our ids match any regs they're supposed to */
4809                 return check_ids(rold->id, rcur->id, idmap);
4810         case PTR_TO_PACKET_META:
4811         case PTR_TO_PACKET:
4812                 if (rcur->type != rold->type)
4813                         return false;
4814                 /* We must have at least as much range as the old ptr
4815                  * did, so that any accesses which were safe before are
4816                  * still safe.  This is true even if old range < old off,
4817                  * since someone could have accessed through (ptr - k), or
4818                  * even done ptr -= k in a register, to get a safe access.
4819                  */
4820                 if (rold->range > rcur->range)
4821                         return false;
4822                 /* If the offsets don't match, we can't trust our alignment;
4823                  * nor can we be sure that we won't fall out of range.
4824                  */
4825                 if (rold->off != rcur->off)
4826                         return false;
4827                 /* id relations must be preserved */
4828                 if (rold->id && !check_ids(rold->id, rcur->id, idmap))
4829                         return false;
4830                 /* new val must satisfy old val knowledge */
4831                 return range_within(rold, rcur) &&
4832                        tnum_in(rold->var_off, rcur->var_off);
4833         case PTR_TO_CTX:
4834         case CONST_PTR_TO_MAP:
4835         case PTR_TO_PACKET_END:
4836         case PTR_TO_FLOW_KEYS:
4837         case PTR_TO_SOCKET:
4838         case PTR_TO_SOCKET_OR_NULL:
4839                 /* Only valid matches are exact, which memcmp() above
4840                  * would have accepted
4841                  */
4842         default:
4843                 /* Don't know what's going on, just say it's not safe */
4844                 return false;
4845         }
4846 
4847         /* Shouldn't get here; if we do, say it's not safe */
4848         WARN_ON_ONCE(1);
4849         return false;
4850 }
4851 
4852 static bool stacksafe(struct bpf_func_state *old,
4853                       struct bpf_func_state *cur,
4854                       struct idpair *idmap)
4855 {
4856         int i, spi;
4857 
4858         /* if explored stack has more populated slots than current stack
4859          * such stacks are not equivalent
4860          */
4861         if (old->allocated_stack > cur->allocated_stack)
4862                 return false;
4863 
4864         /* walk slots of the explored stack and ignore any additional
4865          * slots in the current stack, since explored(safe) state
4866          * didn't use them
4867          */
4868         for (i = 0; i < old->allocated_stack; i++) {
4869                 spi = i / BPF_REG_SIZE;
4870 
4871                 if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ))
4872                         /* explored state didn't use this */
4873                         continue;
4874 
4875                 if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
4876                         continue;
4877                 /* if old state was safe with misc data in the stack
4878                  * it will be safe with zero-initialized stack.
4879                  * The opposite is not true
4880                  */
4881                 if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC &&
4882                     cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO)
4883                         continue;
4884                 if (old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
4885                     cur->stack[spi].slot_type[i % BPF_REG_SIZE])
4886                         /* Ex: old explored (safe) state has STACK_SPILL in
4887                          * this stack slot, but current has has STACK_MISC ->
4888                          * this verifier states are not equivalent,
4889                          * return false to continue verification of this path
4890                          */
4891                         return false;
4892                 if (i % BPF_REG_SIZE)
4893                         continue;
4894                 if (old->stack[spi].slot_type[0] != STACK_SPILL)
4895                         continue;
4896                 if (!regsafe(&old->stack[spi].spilled_ptr,
4897                              &cur->stack[spi].spilled_ptr,
4898                              idmap))
4899                         /* when explored and current stack slot are both storing
4900                          * spilled registers, check that stored pointers types
4901                          * are the same as well.
4902                          * Ex: explored safe path could have stored
4903                          * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
4904                          * but current path has stored:
4905                          * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
4906                          * such verifier states are not equivalent.
4907                          * return false to continue verification of this path
4908                          */
4909                         return false;
4910         }
4911         return true;
4912 }
4913 
4914 static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur)
4915 {
4916         if (old->acquired_refs != cur->acquired_refs)
4917                 return false;
4918         return !memcmp(old->refs, cur->refs,
4919                        sizeof(*old->refs) * old->acquired_refs);
4920 }
4921 
4922 /* compare two verifier states
4923  *
4924  * all states stored in state_list are known to be valid, since
4925  * verifier reached 'bpf_exit' instruction through them
4926  *
4927  * this function is called when verifier exploring different branches of
4928  * execution popped from the state stack. If it sees an old state that has
4929  * more strict register state and more strict stack state then this execution
4930  * branch doesn't need to be explored further, since verifier already
4931  * concluded that more strict state leads to valid finish.
4932  *
4933  * Therefore two states are equivalent if register state is more conservative
4934  * and explored stack state is more conservative than the current one.
4935  * Example:
4936  *       explored                   current
4937  * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
4938  * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
4939  *
4940  * In other words if current stack state (one being explored) has more
4941  * valid slots than old one that already passed validation, it means
4942  * the verifier can stop exploring and conclude that current state is valid too
4943  *
4944  * Similarly with registers. If explored state has register type as invalid
4945  * whereas register type in current state is meaningful, it means that
4946  * the current state will reach 'bpf_exit' instruction safely
4947  */
4948 static bool func_states_equal(struct bpf_func_state *old,
4949                               struct bpf_func_state *cur)
4950 {
4951         struct idpair *idmap;
4952         bool ret = false;
4953         int i;
4954 
4955         idmap = kcalloc(ID_MAP_SIZE, sizeof(struct idpair), GFP_KERNEL);
4956         /* If we failed to allocate the idmap, just say it's not safe */
4957         if (!idmap)
4958                 return false;
4959 
4960         for (i = 0; i < MAX_BPF_REG; i++) {
4961                 if (!regsafe(&old->regs[i], &cur->regs[i], idmap))
4962                         goto out_free;
4963         }
4964 
4965         if (!stacksafe(old, cur, idmap))
4966                 goto out_free;
4967 
4968         if (!refsafe(old, cur))
4969                 goto out_free;
4970         ret = true;
4971 out_free:
4972         kfree(idmap);
4973         return ret;
4974 }
4975 
4976 static bool states_equal(struct bpf_verifier_env *env,
4977                          struct bpf_verifier_state *old,
4978                          struct bpf_verifier_state *cur)
4979 {
4980         int i;
4981 
4982         if (old->curframe != cur->curframe)
4983                 return false;
4984 
4985         /* for states to be equal callsites have to be the same
4986          * and all frame states need to be equivalent
4987          */
4988         for (i = 0; i <= old->curframe; i++) {
4989                 if (old->frame[i]->callsite != cur->frame[i]->callsite)
4990                         return false;
4991                 if (!func_states_equal(old->frame[i], cur->frame[i]))
4992                         return false;
4993         }
4994         return true;
4995 }
4996 
4997 /* A write screens off any subsequent reads; but write marks come from the
4998  * straight-line code between a state and its parent.  When we arrive at an
4999  * equivalent state (jump target or such) we didn't arrive by the straight-line
5000  * code, so read marks in the state must propagate to the parent regardless
5001  * of the state's write marks. That's what 'parent == state->parent' comparison
5002  * in mark_reg_read() is for.
5003  */
5004 static int propagate_liveness(struct bpf_verifier_env *env,
5005                               const struct bpf_verifier_state *vstate,
5006                               struct bpf_verifier_state *vparent)
5007 {
5008         int i, frame, err = 0;
5009         struct bpf_func_state *state, *parent;
5010 
5011         if (vparent->curframe != vstate->curframe) {
5012                 WARN(1, "propagate_live: parent frame %d current frame %d\n",
5013                      vparent->curframe, vstate->curframe);
5014                 return -EFAULT;
5015         }
5016         /* Propagate read liveness of registers... */
5017         BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
5018         /* We don't need to worry about FP liveness because it's read-only */
5019         for (i = 0; i < BPF_REG_FP; i++) {
5020                 if (vparent->frame[vparent->curframe]->regs[i].live & REG_LIVE_READ)
5021                         continue;
5022                 if (vstate->frame[vstate->curframe]->regs[i].live & REG_LIVE_READ) {
5023                         err = mark_reg_read(env, &vstate->frame[vstate->curframe]->regs[i],
5024                                             &vparent->frame[vstate->curframe]->regs[i]);
5025                         if (err)
5026                                 return err;
5027                 }
5028         }
5029 
5030         /* ... and stack slots */
5031         for (frame = 0; frame <= vstate->curframe; frame++) {
5032                 state = vstate->frame[frame];
5033                 parent = vparent->frame[frame];
5034                 for (i = 0; i < state->allocated_stack / BPF_REG_SIZE &&
5035                             i < parent->allocated_stack / BPF_REG_SIZE; i++) {
5036                         if (parent->stack[i].spilled_ptr.live & REG_LIVE_READ)
5037                                 continue;
5038                         if (state->stack[i].spilled_ptr.live & REG_LIVE_READ)
5039                                 mark_reg_read(env, &state->stack[i].spilled_ptr,
5040                                               &parent->stack[i].spilled_ptr);
5041                 }
5042         }
5043         return err;
5044 }
5045 
5046 static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
5047 {
5048         struct bpf_verifier_state_list *new_sl;
5049         struct bpf_verifier_state_list *sl;
5050         struct bpf_verifier_state *cur = env->cur_state, *new;
5051         int i, j, err, states_cnt = 0;
5052 
5053         sl = env->explored_states[insn_idx];
5054         if (!sl)
5055                 /* this 'insn_idx' instruction wasn't marked, so we will not
5056                  * be doing state search here
5057                  */
5058                 return 0;
5059 
5060         while (sl != STATE_LIST_MARK) {
5061                 if (states_equal(env, &sl->state, cur)) {
5062                         /* reached equivalent register/stack state,
5063                          * prune the search.
5064                          * Registers read by the continuation are read by us.
5065                          * If we have any write marks in env->cur_state, they
5066                          * will prevent corresponding reads in the continuation
5067                          * from reaching our parent (an explored_state).  Our
5068                          * own state will get the read marks recorded, but
5069                          * they'll be immediately forgotten as we're pruning
5070                          * this state and will pop a new one.
5071                          */
5072                         err = propagate_liveness(env, &sl->state, cur);
5073                         if (err)
5074                                 return err;
5075                         return 1;
5076                 }
5077                 sl = sl->next;
5078                 states_cnt++;
5079         }
5080 
5081         if (!env->allow_ptr_leaks && states_cnt > BPF_COMPLEXITY_LIMIT_STATES)
5082                 return 0;
5083 
5084         /* there were no equivalent states, remember current one.
5085          * technically the current state is not proven to be safe yet,
5086          * but it will either reach outer most bpf_exit (which means it's safe)
5087          * or it will be rejected. Since there are no loops, we won't be
5088          * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
5089          * again on the way to bpf_exit
5090          */
5091         new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
5092         if (!new_sl)
5093                 return -ENOMEM;
5094 
5095         /* add new state to the head of linked list */
5096         new = &new_sl->state;
5097         err = copy_verifier_state(new, cur);
5098         if (err) {
5099                 free_verifier_state(new, false);
5100                 kfree(new_sl);
5101                 return err;
5102         }
5103         new_sl->next = env->explored_states[insn_idx];
5104         env->explored_states[insn_idx] = new_sl;
5105         /* connect new state to parentage chain */
5106         for (i = 0; i < BPF_REG_FP; i++)
5107                 cur_regs(env)[i].parent = &new->frame[new->curframe]->regs[i];
5108         /* clear write marks in current state: the writes we did are not writes
5109          * our child did, so they don't screen off its reads from us.
5110          * (There are no read marks in current state, because reads always mark
5111          * their parent and current state never has children yet.  Only
5112          * explored_states can get read marks.)
5113          */
5114         for (i = 0; i < BPF_REG_FP; i++)
5115                 cur->frame[cur->curframe]->regs[i].live = REG_LIVE_NONE;
5116 
5117         /* all stack frames are accessible from callee, clear them all */
5118         for (j = 0; j <= cur->curframe; j++) {
5119                 struct bpf_func_state *frame = cur->frame[j];
5120                 struct bpf_func_state *newframe = new->frame[j];
5121 
5122                 for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) {
5123                         frame->stack[i].spilled_ptr.live = REG_LIVE_NONE;
5124                         frame->stack[i].spilled_ptr.parent =
5125                                                 &newframe->stack[i].spilled_ptr;
5126                 }
5127         }
5128         return 0;
5129 }
5130 
5131 /* Return true if it's OK to have the same insn return a different type. */
5132 static bool reg_type_mismatch_ok(enum bpf_reg_type type)
5133 {
5134         switch (type) {
5135         case PTR_TO_CTX:
5136         case PTR_TO_SOCKET:
5137         case PTR_TO_SOCKET_OR_NULL:
5138                 return false;
5139         default:
5140                 return true;
5141         }
5142 }
5143 
5144 /* If an instruction was previously used with particular pointer types, then we
5145  * need to be careful to avoid cases such as the below, where it may be ok
5146  * for one branch accessing the pointer, but not ok for the other branch:
5147  *
5148  * R1 = sock_ptr
5149  * goto X;
5150  * ...
5151  * R1 = some_other_valid_ptr;
5152  * goto X;
5153  * ...
5154  * R2 = *(u32 *)(R1 + 0);
5155  */
5156 static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
5157 {
5158         return src != prev && (!reg_type_mismatch_ok(src) ||
5159                                !reg_type_mismatch_ok(prev));
5160 }
5161 
5162 static int do_check(struct bpf_verifier_env *env)
5163 {
5164         struct bpf_verifier_state *state;
5165         struct bpf_insn *insns = env->prog->insnsi;
5166         struct bpf_reg_state *regs;
5167         int insn_cnt = env->prog->len, i;
5168         int insn_idx, prev_insn_idx = 0;
5169         int insn_processed = 0;
5170         bool do_print_state = false;
5171 
5172         state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
5173         if (!state)
5174                 return -ENOMEM;
5175         state->curframe = 0;
5176         state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL);
5177         if (!state->frame[0]) {
5178                 kfree(state);
5179                 return -ENOMEM;
5180         }
5181         env->cur_state = state;
5182         init_func_state(env, state->frame[0],
5183                         BPF_MAIN_FUNC /* callsite */,
5184                         0 /* frameno */,
5185                         0 /* subprogno, zero == main subprog */);
5186         insn_idx = 0;
5187         for (;;) {
5188                 struct bpf_insn *insn;
5189                 u8 class;
5190                 int err;
5191 
5192                 if (insn_idx >= insn_cnt) {
5193                         verbose(env, "invalid insn idx %d insn_cnt %d\n",
5194                                 insn_idx, insn_cnt);
5195                         return -EFAULT;
5196                 }
5197 
5198                 insn = &insns[insn_idx];
5199                 class = BPF_CLASS(insn->code);
5200 
5201                 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
5202                         verbose(env,
5203                                 "BPF program is too large. Processed %d insn\n",
5204                                 insn_processed);
5205                         return -E2BIG;
5206                 }
5207 
5208                 err = is_state_visited(env, insn_idx);
5209                 if (err < 0)
5210                         return err;
5211                 if (err == 1) {
5212                         /* found equivalent state, can prune the search */
5213                         if (env->log.level) {
5214                                 if (do_print_state)
5215                                         verbose(env, "\nfrom %d to %d: safe\n",
5216                                                 prev_insn_idx, insn_idx);
5217                                 else
5218                                         verbose(env, "%d: safe\n", insn_idx);
5219                         }
5220                         goto process_bpf_exit;
5221                 }
5222 
5223                 if (signal_pending(current))
5224                         return -EAGAIN;
5225 
5226                 if (need_resched())
5227                         cond_resched();
5228 
5229                 if (env->log.level > 1 || (env->log.level && do_print_state)) {
5230                         if (env->log.level > 1)
5231                                 verbose(env, "%d:", insn_idx);
5232                         else
5233                                 verbose(env, "\nfrom %d to %d:",
5234                                         prev_insn_idx, insn_idx);
5235                         print_verifier_state(env, state->frame[state->curframe]);
5236                         do_print_state = false;
5237                 }
5238 
5239                 if (env->log.level) {
5240                         const struct bpf_insn_cbs cbs = {
5241                                 .cb_print       = verbose,
5242                                 .private_data   = env,
5243                         };
5244 
5245                         verbose(env, "%d: ", insn_idx);
5246                         print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
5247                 }
5248 
5249                 if (bpf_prog_is_dev_bound(env->prog->aux)) {
5250                         err = bpf_prog_offload_verify_insn(env, insn_idx,
5251                                                            prev_insn_idx);
5252                         if (err)
5253                                 return err;
5254                 }
5255 
5256                 regs = cur_regs(env);
5257                 env->insn_aux_data[insn_idx].seen = true;
5258 
5259                 if (class == BPF_ALU || class == BPF_ALU64) {
5260                         err = check_alu_op(env, insn);
5261                         if (err)
5262                                 return err;
5263 
5264                 } else if (class == BPF_LDX) {
5265                         enum bpf_reg_type *prev_src_type, src_reg_type;
5266 
5267                         /* check for reserved fields is already done */
5268 
5269                         /* check src operand */
5270                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
5271                         if (err)
5272                                 return err;
5273 
5274                         err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
5275                         if (err)
5276                                 return err;
5277 
5278                         src_reg_type = regs[insn->src_reg].type;
5279 
5280                         /* check that memory (src_reg + off) is readable,
5281                          * the state of dst_reg will be updated by this func
5282                          */
5283                         err = check_mem_access(env, insn_idx, insn->src_reg, insn->off,
5284                                                BPF_SIZE(insn->code), BPF_READ,
5285                                                insn->dst_reg, false);
5286                         if (err)
5287                                 return err;
5288 
5289                         prev_src_type = &env->insn_aux_data[insn_idx].ptr_type;
5290 
5291                         if (*prev_src_type == NOT_INIT) {
5292                                 /* saw a valid insn
5293                                  * dst_reg = *(u32 *)(src_reg + off)
5294                                  * save type to validate intersecting paths
5295                                  */
5296                                 *prev_src_type = src_reg_type;
5297 
5298                         } else if (reg_type_mismatch(src_reg_type, *prev_src_type)) {
5299                                 /* ABuser program is trying to use the same insn
5300                                  * dst_reg = *(u32*) (src_reg + off)
5301                                  * with different pointer types:
5302                                  * src_reg == ctx in one branch and
5303                                  * src_reg == stack|map in some other branch.
5304                                  * Reject it.
5305                                  */
5306                                 verbose(env, "same insn cannot be used with different pointers\n");
5307                                 return -EINVAL;
5308                         }
5309 
5310                 } else if (class == BPF_STX) {
5311                         enum bpf_reg_type *prev_dst_type, dst_reg_type;
5312 
5313                         if (BPF_MODE(insn->code) == BPF_XADD) {
5314                                 err = check_xadd(env, insn_idx, insn);
5315                                 if (err)
5316                                         return err;
5317                                 insn_idx++;
5318                                 continue;
5319                         }
5320 
5321                         /* check src1 operand */
5322                         err = check_reg_arg(env, insn->src_reg, SRC_OP);
5323                         if (err)
5324                                 return err;
5325                         /* check src2 operand */
5326                         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
5327                         if (err)
5328                                 return err;
5329 
5330                         dst_reg_type = regs[insn->dst_reg].type;
5331 
5332                         /* check that memory (dst_reg + off) is writeable */
5333                         err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
5334                                                BPF_SIZE(insn->code), BPF_WRITE,
5335                                                insn->src_reg, false);
5336                         if (err)
5337                                 return err;
5338 
5339                         prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type;
5340 
5341                         if (*prev_dst_type == NOT_INIT) {
5342                                 *prev_dst_type = dst_reg_type;
5343                         } else if (reg_type_mismatch(dst_reg_type, *prev_dst_type)) {
5344                                 verbose(env, "same insn cannot be used with different pointers\n");
5345                                 return -EINVAL;
5346                         }
5347 
5348                 } else if (class == BPF_ST) {
5349                         if (BPF_MODE(insn->code) != BPF_MEM ||
5350                             insn->src_reg != BPF_REG_0) {
5351                                 verbose(env, "BPF_ST uses reserved fields\n");
5352                                 return -EINVAL;
5353                         }
5354                         /* check src operand */
5355                         err = check_reg_arg(env, insn->dst_reg, SRC_OP);
5356                         if (err)
5357                                 return err;
5358 
5359                         if (is_ctx_reg(env, insn->dst_reg)) {
5360                                 verbose(env, "BPF_ST stores into R%d %s is not allowed\n",
5361                                         insn->dst_reg,
5362                                         reg_type_str[reg_state(env, insn->dst_reg)->type]);
5363                                 return -EACCES;
5364                         }
5365 
5366                         /* check that memory (dst_reg + off) is writeable */
5367                         err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
5368                                                BPF_SIZE(insn->code), BPF_WRITE,
5369                                                -1, false);
5370                         if (err)
5371                                 return err;
5372 
5373                 } else if (class == BPF_JMP) {
5374                         u8 opcode = BPF_OP(insn->code);
5375 
5376                         if (opcode == BPF_CALL) {
5377                                 if (BPF_SRC(insn->code) != BPF_K ||
5378                                     insn->off != 0 ||
5379                                     (insn->src_reg != BPF_REG_0 &&
5380                                      insn->src_reg != BPF_PSEUDO_CALL) ||
5381                                     insn->dst_reg != BPF_REG_0) {
5382                                         verbose(env, "BPF_CALL uses reserved fields\n");
5383                                         return -EINVAL;
5384                                 }
5385 
5386                                 if (insn->src_reg == BPF_PSEUDO_CALL)
5387                                         err = check_func_call(env, insn, &insn_idx);
5388                                 else
5389                                         err = check_helper_call(env, insn->imm, insn_idx);
5390                                 if (err)
5391                                         return err;
5392 
5393                         } else if (opcode == BPF_JA) {
5394                                 if (BPF_SRC(insn->code) != BPF_K ||
5395                                     insn->imm != 0 ||
5396                                     insn->src_reg != BPF_REG_0 ||
5397                                     insn->dst_reg != BPF_REG_0) {
5398                                         verbose(env, "BPF_JA uses reserved fields\n");
5399                                         return -EINVAL;
5400                                 }
5401 
5402                                 insn_idx += insn->off + 1;
5403                                 continue;
5404 
5405                         } else if (opcode == BPF_EXIT) {
5406                                 if (BPF_SRC(insn->code) != BPF_K ||
5407                                     insn->imm != 0 ||
5408                                     insn->src_reg != BPF_REG_0 ||
5409                                     insn->dst_reg != BPF_REG_0) {
5410                                         verbose(env, "BPF_EXIT uses reserved fields\n");
5411                                         return -EINVAL;
5412                                 }
5413 
5414                                 if (state->curframe) {
5415                                         /* exit from nested function */
5416                                         prev_insn_idx = insn_idx;
5417                                         err = prepare_func_exit(env, &insn_idx);
5418                                         if (err)
5419                                                 return err;
5420                                         do_print_state = true;
5421                                         continue;
5422                                 }
5423 
5424                                 err = check_reference_leak(env);
5425                                 if (err)
5426                                         return err;
5427 
5428                                 /* eBPF calling convetion is such that R0 is used
5429                                  * to return the value from eBPF program.
5430                                  * Make sure that it's readable at this time
5431                                  * of bpf_exit, which means that program wrote
5432                                  * something into it earlier
5433                                  */
5434                                 err = check_reg_arg(env, BPF_REG_0, SRC_OP);
5435                                 if (err)
5436                                         return err;
5437 
5438                                 if (is_pointer_value(env, BPF_REG_0)) {
5439                                         verbose(env, "R0 leaks addr as return value\n");
5440                                         return -EACCES;
5441                                 }
5442 
5443                                 err = check_return_code(env);
5444                                 if (err)
5445                                         return err;
5446 process_bpf_exit:
5447                                 err = pop_stack(env, &prev_insn_idx, &insn_idx);
5448                                 if (err < 0) {
5449                                         if (err != -ENOENT)
5450                                                 return err;
5451                                         break;
5452                                 } else {
5453                                         do_print_state = true;
5454                                         continue;
5455                                 }
5456                         } else {
5457                                 err = check_cond_jmp_op(env, insn, &insn_idx);
5458                                 if (err)
5459                                         return err;
5460                         }
5461                 } else if (class == BPF_LD) {
5462                         u8 mode = BPF_MODE(insn->code);
5463 
5464                         if (mode == BPF_ABS || mode == BPF_IND) {
5465                                 err = check_ld_abs(env, insn);
5466                                 if (err)
5467                                         return err;
5468 
5469                         } else if (mode == BPF_IMM) {
5470                                 err = check_ld_imm(env, insn);
5471                                 if (err)
5472                                         return err;
5473 
5474                                 insn_idx++;
5475                                 env->insn_aux_data[insn_idx].seen = true;
5476                         } else {
5477                                 verbose(env, "invalid BPF_LD mode\n");
5478                                 return -EINVAL;
5479                         }
5480                 } else {
5481                         verbose(env, "unknown insn class %d\n", class);
5482                         return -EINVAL;
5483                 }
5484 
5485                 insn_idx++;
5486         }
5487 
5488         verbose(env, "processed %d insns (limit %d), stack depth ",
5489                 insn_processed, BPF_COMPLEXITY_LIMIT_INSNS);
5490         for (i = 0; i < env->subprog_cnt; i++) {
5491                 u32 depth = env->subprog_info[i].stack_depth;
5492 
5493                 verbose(env, "%d", depth);
5494                 if (i + 1 < env->subprog_cnt)
5495                         verbose(env, "+");
5496         }
5497         verbose(env, "\n");
5498         env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
5499         return 0;
5500 }
5501 
5502 static int check_map_prealloc(struct bpf_map *map)
5503 {
5504         return (map->map_type != BPF_MAP_TYPE_HASH &&
5505                 map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
5506                 map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
5507                 !(map->map_flags & BPF_F_NO_PREALLOC);
5508 }
5509 
5510 static int check_map_prog_compatibility(struct bpf_verifier_env *env,
5511                                         struct bpf_map *map,
5512                                         struct bpf_prog *prog)
5513 
5514 {
5515         /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
5516          * preallocated hash maps, since doing memory allocation
5517          * in overflow_handler can crash depending on where nmi got
5518          * triggered.
5519          */
5520         if (prog->type == BPF_PROG_TYPE_PERF_EVENT) {
5521                 if (!check_map_prealloc(map)) {
5522                         verbose(env, "perf_event programs can only use preallocated hash map\n");
5523                         return -EINVAL;
5524                 }
5525                 if (map->inner_map_meta &&
5526                     !check_map_prealloc(map->inner_map_meta)) {
5527                         verbose(env, "perf_event programs can only use preallocated inner hash map\n");
5528                         return -EINVAL;
5529                 }
5530         }
5531 
5532         if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) &&
5533             !bpf_offload_prog_map_match(prog, map)) {
5534                 verbose(env, "offload device mismatch between prog and map\n");
5535                 return -EINVAL;
5536         }
5537 
5538         return 0;
5539 }
5540 
5541 static bool bpf_map_is_cgroup_storage(struct bpf_map *map)
5542 {
5543         return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
5544                 map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
5545 }
5546 
5547 /* look for pseudo eBPF instructions that access map FDs and
5548  * replace them with actual map pointers
5549  */
5550 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
5551 {
5552         struct bpf_insn *insn = env->prog->insnsi;
5553         int insn_cnt = env->prog->len;
5554         int i, j, err;
5555 
5556         err = bpf_prog_calc_tag(env->prog);
5557         if (err)
5558                 return err;
5559 
5560         for (i = 0; i < insn_cnt; i++, insn++) {
5561                 if (BPF_CLASS(insn->code) == BPF_LDX &&
5562                     (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
5563                         verbose(env, "BPF_LDX uses reserved fields\n");
5564                         return -EINVAL;
5565                 }
5566 
5567                 if (BPF_CLASS(insn->code) == BPF_STX &&
5568                     ((BPF_MODE(insn->code) != BPF_MEM &&
5569                       BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
5570                         verbose(env, "BPF_STX uses reserved fields\n");
5571                         return -EINVAL;
5572                 }
5573 
5574                 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
5575                         struct bpf_map *map;
5576                         struct fd f;
5577 
5578                         if (i == insn_cnt - 1 || insn[1].code != 0 ||
5579                             insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
5580                             insn[1].off != 0) {
5581                                 verbose(env, "invalid bpf_ld_imm64 insn\n");
5582                                 return -EINVAL;
5583                         }
5584 
5585                         if (insn->src_reg == 0)
5586                                 /* valid generic load 64-bit imm */
5587                                 goto next_insn;
5588 
5589                         if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
5590                                 verbose(env,
5591                                         "unrecognized bpf_ld_imm64 insn\n");
5592                                 return -EINVAL;
5593                         }
5594 
5595                         f = fdget(insn->imm);
5596                         map = __bpf_map_get(f);
5597                         if (IS_ERR(map)) {
5598                                 verbose(env, "fd %d is not pointing to valid bpf_map\n",
5599                                         insn->imm);
5600                                 return PTR_ERR(map);
5601                         }
5602 
5603                         err = check_map_prog_compatibility(env, map, env->prog);
5604                         if (err) {
5605                                 fdput(f);
5606                                 return err;
5607                         }
5608 
5609                         /* store map pointer inside BPF_LD_IMM64 instruction */
5610                         insn[0].imm = (u32) (unsigned long) map;
5611                         insn[1].imm = ((u64) (unsigned long) map) >> 32;
5612 
5613                         /* check whether we recorded this map already */
5614                         for (j = 0; j < env->used_map_cnt; j++)
5615                                 if (env->used_maps[j] == map) {
5616                                         fdput(f);
5617                                         goto next_insn;
5618                                 }
5619 
5620                         if (env->used_map_cnt >= MAX_USED_MAPS) {
5621                                 fdput(f);
5622                                 return -E2BIG;
5623                         }
5624 
5625                         /* hold the map. If the program is rejected by verifier,
5626                          * the map will be released by release_maps() or it
5627                          * will be used by the valid program until it's unloaded
5628                          * and all maps are released in free_used_maps()
5629                          */
5630                         map = bpf_map_inc(map, false);
5631                         if (IS_ERR(map)) {
5632                                 fdput(f);
5633                                 return PTR_ERR(map);
5634                         }
5635                         env->used_maps[env->used_map_cnt++] = map;
5636 
5637                         if (bpf_map_is_cgroup_storage(map) &&
5638                             bpf_cgroup_storage_assign(env->prog, map)) {
5639                                 verbose(env, "only one cgroup storage of each type is allowed\n");
5640                                 fdput(f);
5641                                 return -EBUSY;
5642                         }
5643 
5644                         fdput(f);
5645 next_insn:
5646                         insn++;
5647                         i++;
5648                         continue;
5649                 }
5650 
5651                 /* Basic sanity check before we invest more work here. */
5652                 if (!bpf_opcode_in_insntable(insn->code)) {
5653                         verbose(env, "unknown opcode %02x\n", insn->code);
5654                         return -EINVAL;
5655                 }
5656         }
5657 
5658         /* now all pseudo BPF_LD_IMM64 instructions load valid
5659          * 'struct bpf_map *' into a register instead of user map_fd.
5660          * These pointers will be used later by verifier to validate map access.
5661          */
5662         return 0;
5663 }
5664 
5665 /* drop refcnt of maps used by the rejected program */
5666 static void release_maps(struct bpf_verifier_env *env)
5667 {
5668         enum bpf_cgroup_storage_type stype;
5669         int i;
5670 
5671         for_each_cgroup_storage_type(stype) {
5672                 if (!env->prog->aux->cgroup_storage[stype])
5673                         continue;
5674                 bpf_cgroup_storage_release(env->prog,
5675                         env->prog->aux->cgroup_storage[stype]);
5676         }
5677 
5678         for (i = 0; i < env->used_map_cnt; i++)
5679                 bpf_map_put(env->used_maps[i]);
5680 }
5681 
5682 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
5683 static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
5684 {
5685         struct bpf_insn *insn = env->prog->insnsi;
5686         int insn_cnt = env->prog->len;
5687         int i;
5688 
5689         for (i = 0; i < insn_cnt; i++, insn++)
5690                 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
5691                         insn->src_reg = 0;
5692 }
5693 
5694 /* single env->prog->insni[off] instruction was replaced with the range
5695  * insni[off, off + cnt).  Adjust corresponding insn_aux_data by copying
5696  * [0, off) and [off, end) to new locations, so the patched range stays zero
5697  */
5698 static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
5699                                 u32 off, u32 cnt)
5700 {
5701         struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
5702         int i;
5703 
5704         if (cnt == 1)
5705                 return 0;
5706         new_data = vzalloc(array_size(prog_len,
5707                                       sizeof(struct bpf_insn_aux_data)));
5708         if (!new_data)
5709                 return -ENOMEM;
5710         memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
5711         memcpy(new_data + off + cnt - 1, old_data + off,
5712                sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
5713         for (i = off; i < off + cnt - 1; i++)
5714                 new_data[i].seen = true;
5715         env->insn_aux_data = new_data;
5716         vfree(old_data);
5717         return 0;
5718 }
5719 
5720 static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
5721 {
5722         int i;
5723 
5724         if (len == 1)
5725                 return;
5726         /* NOTE: fake 'exit' subprog should be updated as well. */
5727         for (i = 0; i <= env->subprog_cnt; i++) {
5728                 if (env->subprog_info[i].start <= off)
5729                         continue;
5730                 env->subprog_info[i].start += len - 1;
5731         }
5732 }
5733 
5734 static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
5735                                             const struct bpf_insn *patch, u32 len)
5736 {
5737         struct bpf_prog *new_prog;
5738 
5739         new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
5740         if (!new_prog)
5741                 return NULL;
5742         if (adjust_insn_aux_data(env, new_prog->len, off, len))
5743                 return NULL;
5744         adjust_subprog_starts(env, off, len);
5745         return new_prog;
5746 }
5747 
5748 /* The verifier does more data flow analysis than llvm and will not
5749  * explore branches that are dead at run time. Malicious programs can
5750  * have dead code too. Therefore replace all dead at-run-time code
5751  * with 'ja -1'.
5752  *
5753  * Just nops are not optimal, e.g. if they would sit at the end of the
5754  * program and through another bug we would manage to jump there, then
5755  * we'd execute beyond program memory otherwise. Returning exception
5756  * code also wouldn't work since we can have subprogs where the dead
5757  * code could be located.
5758  */
5759 static void sanitize_dead_code(struct bpf_verifier_env *env)
5760 {
5761         struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
5762         struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
5763         struct bpf_insn *insn = env->prog->insnsi;
5764         const int insn_cnt = env->prog->len;
5765         int i;
5766 
5767         for (i = 0; i < insn_cnt; i++) {
5768                 if (aux_data[i].seen)
5769                         continue;
5770                 memcpy(insn + i, &trap, sizeof(trap));
5771         }
5772 }
5773 
5774 /* convert load instructions that access fields of a context type into a
5775  * sequence of instructions that access fields of the underlying structure:
5776  *     struct __sk_buff    -> struct sk_buff
5777  *     struct bpf_sock_ops -> struct sock
5778  */
5779 static int convert_ctx_accesses(struct bpf_verifier_env *env)
5780 {
5781         const struct bpf_verifier_ops *ops = env->ops;
5782         int i, cnt, size, ctx_field_size, delta = 0;
5783         const int insn_cnt = env->prog->len;
5784         struct bpf_insn insn_buf[16], *insn;
5785         struct bpf_prog *new_prog;
5786         enum bpf_access_type type;
5787         bool is_narrower_load;
5788         u32 target_size;
5789 
5790         if (ops->gen_prologue || env->seen_direct_write) {
5791                 if (!ops->gen_prologue) {
5792                         verbose(env, "bpf verifier is misconfigured\n");
5793                         return -EINVAL;
5794                 }
5795                 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
5796                                         env->prog);
5797                 if (cnt >= ARRAY_SIZE(insn_buf)) {
5798                         verbose(env, "bpf verifier is misconfigured\n");
5799                         return -EINVAL;
5800                 } else if (cnt) {
5801                         new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
5802                         if (!new_prog)
5803                                 return -ENOMEM;
5804 
5805                         env->prog = new_prog;
5806                         delta += cnt - 1;
5807                 }
5808         }
5809 
5810         if (bpf_prog_is_dev_bound(env->prog->aux))
5811                 return 0;
5812 
5813         insn = env->prog->insnsi + delta;
5814 
5815         for (i = 0; i < insn_cnt; i++, insn++) {
5816                 bpf_convert_ctx_access_t convert_ctx_access;
5817 
5818                 if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
5819                     insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
5820                     insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
5821                     insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
5822                         type = BPF_READ;
5823                 else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
5824                          insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
5825                          insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
5826                          insn->code == (BPF_STX | BPF_MEM | BPF_DW))
5827                         type = BPF_WRITE;
5828                 else
5829                         continue;
5830 
5831                 if (type == BPF_WRITE &&
5832                     env->insn_aux_data[i + delta].sanitize_stack_off) {
5833                         struct bpf_insn patch[] = {
5834                                 /* Sanitize suspicious stack slot with zero.
5835                                  * There are no memory dependencies for this store,
5836                                  * since it's only using frame pointer and immediate
5837                                  * constant of zero
5838                                  */
5839                                 BPF_ST_MEM(BPF_DW, BPF_REG_FP,
5840                                            env->insn_aux_data[i + delta].sanitize_stack_off,
5841                                            0),
5842                                 /* the original STX instruction will immediately
5843                                  * overwrite the same stack slot with appropriate value
5844                                  */
5845                                 *insn,
5846                         };
5847 
5848                         cnt = ARRAY_SIZE(patch);
5849                         new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
5850                         if (!new_prog)
5851                                 return -ENOMEM;
5852 
5853                         delta    += cnt - 1;
5854                         env->prog = new_prog;
5855                         insn      = new_prog->insnsi + i + delta;
5856                         continue;
5857                 }
5858 
5859                 switch (env->insn_aux_data[i + delta].ptr_type) {
5860                 case PTR_TO_CTX:
5861                         if (!ops->convert_ctx_access)
5862                                 continue;
5863                         convert_ctx_access = ops->convert_ctx_access;
5864                         break;
5865                 case PTR_TO_SOCKET:
5866                         convert_ctx_access = bpf_sock_convert_ctx_access;
5867                         break;
5868                 default:
5869                         continue;
5870                 }
5871 
5872                 ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
5873                 size = BPF_LDST_BYTES(insn);
5874 
5875                 /* If the read access is a narrower load of the field,
5876                  * convert to a 4/8-byte load, to minimum program type specific
5877                  * convert_ctx_access changes. If conversion is successful,
5878                  * we will apply proper mask to the result.
5879                  */
5880                 is_narrower_load = size < ctx_field_size;
5881                 if (is_narrower_load) {
5882                         u32 size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
5883                         u32 off = insn->off;
5884                         u8 size_code;
5885 
5886                         if (type == BPF_WRITE) {
5887                                 verbose(env, "bpf verifier narrow ctx access misconfigured\n");
5888                                 return -EINVAL;
5889                         }
5890 
5891                         size_code = BPF_H;
5892                         if (ctx_field_size == 4)
5893                                 size_code = BPF_W;
5894                         else if (ctx_field_size == 8)
5895                                 size_code = BPF_DW;
5896 
5897                         insn->off = off & ~(size_default - 1);
5898                         insn->code = BPF_LDX | BPF_MEM | size_code;
5899                 }
5900 
5901                 target_size = 0;
5902                 cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
5903                                          &target_size);
5904                 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
5905                     (ctx_field_size && !target_size)) {
5906                         verbose(env, "bpf verifier is misconfigured\n");
5907                         return -EINVAL;
5908                 }
5909 
5910                 if (is_narrower_load && size < target_size) {
5911                         if (ctx_field_size <= 4)
5912                                 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
5913                                                                 (1 << size * 8) - 1);
5914                         else
5915                                 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
5916                                                                 (1 << size * 8) - 1);
5917                 }
5918 
5919                 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
5920                 if (!new_prog)
5921                         return -ENOMEM;
5922 
5923                 delta += cnt - 1;
5924 
5925                 /* keep walking new program and skip insns we just inserted */
5926                 env->prog = new_prog;
5927                 insn      = new_prog->insnsi + i + delta;
5928         }
5929 
5930         return 0;
5931 }
5932 
5933 static int jit_subprogs(struct bpf_verifier_env *env)
5934 {
5935         struct bpf_prog *prog = env->prog, **func, *tmp;
5936         int i, j, subprog_start, subprog_end = 0, len, subprog;
5937         struct bpf_insn *insn;
5938         void *old_bpf_func;
5939         int err = -ENOMEM;
5940 
5941         if (env->subprog_cnt <= 1)
5942                 return 0;
5943 
5944         for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
5945                 if (insn->code != (BPF_JMP | BPF_CALL) ||
5946                     insn->src_reg != BPF_PSEUDO_CALL)
5947                         continue;
5948                 /* Upon error here we cannot fall back to interpreter but
5949                  * need a hard reject of the program. Thus -EFAULT is
5950                  * propagated in any case.
5951                  */
5952                 subprog = find_subprog(env, i + insn->imm + 1);
5953                 if (subprog < 0) {
5954                         WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
5955                                   i + insn->imm + 1);
5956                         return -EFAULT;
5957                 }
5958                 /* temporarily remember subprog id inside insn instead of
5959                  * aux_data, since next loop will split up all insns into funcs
5960                  */
5961                 insn->off = subprog;
5962                 /* remember original imm in case JIT fails and fallback
5963                  * to interpreter will be needed
5964                  */
5965                 env->insn_aux_data[i].call_imm = insn->imm;
5966                 /* point imm to __bpf_call_base+1 from JITs point of view */
5967                 insn->imm = 1;
5968         }
5969 
5970         func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
5971         if (!func)
5972                 goto out_undo_insn;
5973 
5974         for (i = 0; i < env->subprog_cnt; i++) {
5975                 subprog_start = subprog_end;
5976                 subprog_end = env->subprog_info[i + 1].start;
5977 
5978                 len = subprog_end - subprog_start;
5979                 func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);
5980                 if (!func[i])
5981                         goto out_free;
5982                 memcpy(func[i]->insnsi, &prog->insnsi[subprog_start],
5983                        len * sizeof(struct bpf_insn));
5984                 func[i]->type = prog->type;
5985                 func[i]->len = len;
5986                 if (bpf_prog_calc_tag(func[i]))
5987                         goto out_free;
5988                 func[i]->is_func = 1;
5989                 /* Use bpf_prog_F_tag to indicate functions in stack traces.
5990                  * Long term would need debug info to populate names
5991                  */
5992                 func[i]->aux->name[0] = 'F';
5993                 func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
5994                 func[i]->jit_requested = 1;
5995                 func[i] = bpf_int_jit_compile(func[i]);
5996                 if (!func[i]->jited) {
5997                         err = -ENOTSUPP;
5998                         goto out_free;
5999                 }
6000                 cond_resched();
6001         }
6002         /* at this point all bpf functions were successfully JITed
6003          * now populate all bpf_calls with correct addresses and
6004          * run last pass of JIT
6005          */
6006         for (i = 0; i < env->subprog_cnt; i++) {
6007                 insn = func[i]->insnsi;
6008                 for (j = 0; j < func[i]->len; j++, insn++) {
6009                         if (insn->code != (BPF_JMP | BPF_CALL) ||
6010                             insn->src_reg != BPF_PSEUDO_CALL)
6011                                 continue;
6012                         subprog = insn->off;
6013                         insn->imm = (u64 (*)(u64, u64, u64, u64, u64))
6014                                 func[subprog]->bpf_func -
6015                                 __bpf_call_base;
6016                 }
6017 
6018                 /* we use the aux data to keep a list of the start addresses
6019                  * of the JITed images for each function in the program
6020                  *
6021                  * for some architectures, such as powerpc64, the imm field
6022                  * might not be large enough to hold the offset of the start
6023                  * address of the callee's JITed image from __bpf_call_base
6024                  *
6025                  * in such cases, we can lookup the start address of a callee
6026                  * by using its subprog id, available from the off field of
6027                  * the call instruction, as an index for this list
6028                  */
6029                 func[i]->aux->func = func;
6030                 func[i]->aux->func_cnt = env->subprog_cnt;
6031         }
6032         for (i = 0; i < env->subprog_cnt; i++) {
6033                 old_bpf_func = func[i]->bpf_func;
6034                 tmp = bpf_int_jit_compile(func[i]);
6035                 if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
6036                         verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
6037                         err = -ENOTSUPP;
6038                         goto out_free;
6039                 }
6040                 cond_resched();
6041         }
6042 
6043         /* finally lock prog and jit images for all functions and
6044          * populate kallsysm
6045          */
6046         for (i = 0; i < env->subprog_cnt; i++) {
6047                 bpf_prog_lock_ro(func[i]);
6048                 bpf_prog_kallsyms_add(func[i]);
6049         }
6050 
6051         /* Last step: make now unused interpreter insns from main
6052          * prog consistent for later dump requests, so they can
6053          * later look the same as if they were interpreted only.
6054          */
6055         for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
6056                 if (insn->code != (BPF_JMP | BPF_CALL) ||
6057                     insn->src_reg != BPF_PSEUDO_CALL)
6058                         continue;
6059                 insn->off = env->insn_aux_data[i].call_imm;
6060                 subprog = find_subprog(env, i + insn->off + 1);
6061                 insn->imm = subprog;
6062         }
6063 
6064         prog->jited = 1;
6065         prog->bpf_func = func[0]->bpf_func;
6066         prog->aux->func = func;
6067         prog->aux->func_cnt = env->subprog_cnt;
6068         return 0;
6069 out_free:
6070         for (i = 0; i < env->subprog_cnt; i++)
6071                 if (func[i])
6072                         bpf_jit_free(func[i]);
6073         kfree(func);
6074 out_undo_insn:
6075         /* cleanup main prog to be interpreted */
6076         prog->jit_requested = 0;
6077         for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
6078                 if (insn->code != (BPF_JMP | BPF_CALL) ||
6079                     insn->src_reg != BPF_PSEUDO_CALL)
6080                         continue;
6081                 insn->off = 0;
6082                 insn->imm = env->insn_aux_data[i].call_imm;
6083         }
6084         return err;
6085 }
6086 
6087 static int fixup_call_args(struct bpf_verifier_env *env)
6088 {
6089 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
6090         struct bpf_prog *prog = env->prog;
6091         struct bpf_insn *insn = prog->insnsi;
6092         int i, depth;
6093 #endif
6094         int err = 0;
6095 
6096         if (env->prog->jit_requested &&
6097             !bpf_prog_is_dev_bound(env->prog->aux)) {
6098                 err = jit_subprogs(env);
6099                 if (err == 0)
6100                         return 0;
6101                 if (err == -EFAULT)
6102                         return err;
6103         }
6104 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
6105         for (i = 0; i < prog->len; i++, insn++) {
6106                 if (insn->code != (BPF_JMP | BPF_CALL) ||
6107                     insn->src_reg != BPF_PSEUDO_CALL)
6108                         continue;
6109                 depth = get_callee_stack_depth(env, insn, i);
6110                 if (depth < 0)
6111                         return depth;
6112                 bpf_patch_call_args(insn, depth);
6113         }
6114         err = 0;
6115 #endif
6116         return err;
6117 }
6118 
6119 /* fixup insn->imm field of bpf_call instructions
6120  * and inline eligible helpers as explicit sequence of BPF instructions
6121  *
6122  * this function is called after eBPF program passed verification
6123  */
6124 static int fixup_bpf_calls(struct bpf_verifier_env *env)
6125 {
6126         struct bpf_prog *prog = env->prog;
6127         struct bpf_insn *insn = prog->insnsi;
6128         const struct bpf_func_proto *fn;
6129         const int insn_cnt = prog->len;
6130         const struct bpf_map_ops *ops;
6131         struct bpf_insn_aux_data *aux;
6132         struct bpf_insn insn_buf[16];
6133         struct bpf_prog *new_prog;
6134         struct bpf_map *map_ptr;
6135         int i, cnt, delta = 0;
6136 
6137         for (i = 0; i < insn_cnt; i++, insn++) {
6138                 if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) ||
6139                     insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
6140                     insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
6141                     insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
6142                         bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
6143                         struct bpf_insn mask_and_div[] = {
6144                                 BPF_MOV32_REG(insn->src_reg, insn->src_reg),
6145                                 /* Rx div 0 -> 0 */
6146                                 BPF_JMP_IMM(BPF_JNE, insn->src_reg, 0, 2),
6147                                 BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg),
6148                                 BPF_JMP_IMM(BPF_JA, 0, 0, 1),
6149                                 *insn,
6150                         };
6151                         struct bpf_insn mask_and_mod[] = {
6152                                 BPF_MOV32_REG(insn->src_reg, insn->src_reg),
6153                                 /* Rx mod 0 -> Rx */
6154                                 BPF_JMP_IMM(BPF_JEQ, insn->src_reg, 0, 1),
6155                                 *insn,
6156                         };
6157                         struct bpf_insn *patchlet;
6158 
6159                         if (insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
6160                             insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
6161                                 patchlet = mask_and_div + (is64 ? 1 : 0);
6162                                 cnt = ARRAY_SIZE(mask_and_div) - (is64 ? 1 : 0);
6163                         } else {
6164                                 patchlet = mask_and_mod + (is64 ? 1 : 0);
6165                                 cnt = ARRAY_SIZE(mask_and_mod) - (is64 ? 1 : 0);
6166                         }
6167 
6168                         new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
6169                         if (!new_prog)
6170                                 return -ENOMEM;
6171 
6172                         delta    += cnt - 1;
6173                         env->prog = prog = new_prog;
6174                         insn      = new_prog->insnsi + i + delta;
6175                         continue;
6176                 }
6177 
6178                 if (BPF_CLASS(insn->code) == BPF_LD &&
6179                     (BPF_MODE(insn->code) == BPF_ABS ||
6180                      BPF_MODE(insn->code) == BPF_IND)) {
6181                         cnt = env->ops->gen_ld_abs(insn, insn_buf);
6182                         if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
6183                                 verbose(env, "bpf verifier is misconfigured\n");
6184                                 return -EINVAL;
6185                         }
6186 
6187                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
6188                         if (!new_prog)
6189                                 return -ENOMEM;
6190 
6191                         delta    += cnt - 1;
6192                         env->prog = prog = new_prog;
6193                         insn      = new_prog->insnsi + i + delta;
6194                         continue;
6195                 }
6196 
6197                 if (insn->code != (BPF_JMP | BPF_CALL))
6198                         continue;
6199                 if (insn->src_reg == BPF_PSEUDO_CALL)
6200                         continue;
6201 
6202                 if (insn->imm == BPF_FUNC_get_route_realm)
6203                         prog->dst_needed = 1;
6204                 if (insn->imm == BPF_FUNC_get_prandom_u32)
6205                         bpf_user_rnd_init_once();
6206                 if (insn->imm == BPF_FUNC_override_return)
6207                         prog->kprobe_override = 1;
6208                 if (insn->imm == BPF_FUNC_tail_call) {
6209                         /* If we tail call into other programs, we
6210                          * cannot make any assumptions since they can
6211                          * be replaced dynamically during runtime in
6212                          * the program array.
6213                          */
6214                         prog->cb_access = 1;
6215                         env->prog->aux->stack_depth = MAX_BPF_STACK;
6216 
6217                         /* mark bpf_tail_call as different opcode to avoid
6218                          * conditional branch in the interpeter for every normal
6219                          * call and to prevent accidental JITing by JIT compiler
6220                          * that doesn't support bpf_tail_call yet
6221                          */
6222                         insn->imm = 0;
6223                         insn->code = BPF_JMP | BPF_TAIL_CALL;
6224 
6225                         aux = &env->insn_aux_data[i + delta];
6226                         if (!bpf_map_ptr_unpriv(aux))
6227                                 continue;
6228 
6229                         /* instead of changing every JIT dealing with tail_call
6230                          * emit two extra insns:
6231                          * if (index >= max_entries) goto out;
6232                          * index &= array->index_mask;
6233                          * to avoid out-of-bounds cpu speculation
6234                          */
6235                         if (bpf_map_ptr_poisoned(aux)) {
6236                                 verbose(env, "tail_call abusing map_ptr\n");
6237                                 return -EINVAL;
6238                         }
6239 
6240                         map_ptr = BPF_MAP_PTR(aux->map_state);
6241                         insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
6242                                                   map_ptr->max_entries, 2);
6243                         insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
6244                                                     container_of(map_ptr,
6245                                                                  struct bpf_array,
6246                                                                  map)->index_mask);
6247                         insn_buf[2] = *insn;
6248                         cnt = 3;
6249                         new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
6250                         if (!new_prog)
6251                                 return -ENOMEM;
6252 
6253                         delta    += cnt - 1;
6254                         env->prog = prog = new_prog;
6255                         insn      = new_prog->insnsi + i + delta;
6256                         continue;
6257                 }
6258 
6259                 /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
6260                  * and other inlining handlers are currently limited to 64 bit
6261                  * only.
6262                  */
6263                 if (prog->jit_requested && BITS_PER_LONG == 64 &&
6264                     (insn->imm == BPF_FUNC_map_lookup_elem ||
6265                      insn->imm == BPF_FUNC_map_update_elem ||
6266                      insn->imm == BPF_FUNC_map_delete_elem ||
6267                      insn->imm == BPF_FUNC_map_push_elem   ||
6268                      insn->imm == BPF_FUNC_map_pop_elem    ||
6269                      insn->imm == BPF_FUNC_map_peek_elem)) {
6270                         aux = &env->insn_aux_data[i + delta];
6271                         if (bpf_map_ptr_poisoned(aux))
6272                                 goto patch_call_imm;
6273 
6274                         map_ptr = BPF_MAP_PTR(aux->map_state);
6275                         ops = map_ptr->ops;
6276                         if (insn->imm == BPF_FUNC_map_lookup_elem &&
6277                             ops->map_gen_lookup) {
6278                                 cnt = ops->map_gen_lookup(map_ptr, insn_buf);
6279                                 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
6280                                         verbose(env, "bpf verifier is misconfigured\n");
6281                                         return -EINVAL;
6282                                 }
6283 
6284                                 new_prog = bpf_patch_insn_data(env, i + delta,
6285                                                                insn_buf, cnt);
6286                                 if (!new_prog)
6287                                         return -ENOMEM;
6288 
6289                                 delta    += cnt - 1;
6290                                 env->prog = prog = new_prog;
6291                                 insn      = new_prog->insnsi + i + delta;
6292                                 continue;
6293                         }
6294 
6295                         BUILD_BUG_ON(!__same_type(ops->map_lookup_elem,
6296                                      (void *(*)(struct bpf_map *map, void *key))NULL));
6297                         BUILD_BUG_ON(!__same_type(ops->map_delete_elem,
6298                                      (int (*)(struct bpf_map *map, void *key))NULL));
6299                         BUILD_BUG_ON(!__same_type(ops->map_update_elem,
6300                                      (int (*)(struct bpf_map *map, void *key, void *value,
6301                                               u64 flags))NULL));
6302                         BUILD_BUG_ON(!__same_type(ops->map_push_elem,
6303                                      (int (*)(struct bpf_map *map, void *value,
6304                                               u64 flags))NULL));
6305                         BUILD_BUG_ON(!__same_type(ops->map_pop_elem,
6306                                      (int (*)(struct bpf_map *map, void *value))NULL));
6307                         BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
6308                                      (int (*)(struct bpf_map *map, void *value))NULL));
6309 
6310                         switch (insn->imm) {
6311                         case BPF_FUNC_map_lookup_elem:
6312                                 insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) -
6313                                             __bpf_call_base;
6314                                 continue;
6315                         case BPF_FUNC_map_update_elem:
6316                                 insn->imm = BPF_CAST_CALL(ops->map_update_elem) -
6317                                             __bpf_call_base;
6318                                 continue;
6319                         case BPF_FUNC_map_delete_elem:
6320                                 insn->imm = BPF_CAST_CALL(ops->map_delete_elem) -
6321                                             __bpf_call_base;
6322                                 continue;
6323                         case BPF_FUNC_map_push_elem:
6324                                 insn->imm = BPF_CAST_CALL(ops->map_push_elem) -
6325                                             __bpf_call_base;
6326                                 continue;
6327                         case BPF_FUNC_map_pop_elem:
6328                                 insn->imm = BPF_CAST_CALL(ops->map_pop_elem) -
6329                                             __bpf_call_base;
6330                                 continue;
6331                         case BPF_FUNC_map_peek_elem:
6332                                 insn->imm = BPF_CAST_CALL(ops->map_peek_elem) -
6333                                             __bpf_call_base;
6334                                 continue;
6335                         }
6336 
6337                         goto patch_call_imm;
6338                 }
6339 
6340 patch_call_imm:
6341                 fn = env->ops->get_func_proto(insn->imm, env->prog);
6342                 /* all functions that have prototype and verifier allowed
6343                  * programs to call them, must be real in-kernel functions
6344                  */
6345                 if (!fn->func) {
6346                         verbose(env,
6347                                 "kernel subsystem misconfigured func %s#%d\n",
6348                                 func_id_name(insn->imm), insn->imm);
6349                         return -EFAULT;
6350                 }
6351                 insn->imm = fn->func - __bpf_call_base;
6352         }
6353 
6354         return 0;
6355 }
6356 
6357 static void free_states(struct bpf_verifier_env *env)
6358 {
6359         struct bpf_verifier_state_list *sl, *sln;
6360         int i;
6361 
6362         if (!env->explored_states)
6363                 return;
6364 
6365         for (i = 0; i < env->prog->len; i++) {
6366                 sl = env->explored_states[i];
6367 
6368                 if (sl)
6369                         while (sl != STATE_LIST_MARK) {
6370                                 sln = sl->next;
6371                                 free_verifier_state(&sl->state, false);
6372                                 kfree(sl);
6373                                 sl = sln;
6374                         }
6375         }
6376 
6377         kfree(env->explored_states);
6378 }
6379 
6380 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
6381 {
6382         struct bpf_verifier_env *env;
6383         struct bpf_verifier_log *log;
6384         int ret = -EINVAL;
6385 
6386         /* no program is valid */
6387         if (ARRAY_SIZE(bpf_verifier_ops) == 0)
6388                 return -EINVAL;
6389 
6390         /* 'struct bpf_verifier_env' can be global, but since it's not small,
6391          * allocate/free it every time bpf_check() is called
6392          */
6393         env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
6394         if (!env)
6395                 return -ENOMEM;
6396         log = &env->log;
6397 
6398         env->insn_aux_data =
6399                 vzalloc(array_size(sizeof(struct bpf_insn_aux_data),
6400                                    (*prog)->len));
6401         ret = -ENOMEM;
6402         if (!env->insn_aux_data)
6403                 goto err_free_env;
6404         env->prog = *prog;
6405         env->ops = bpf_verifier_ops[env->prog->type];
6406 
6407         /* grab the mutex to protect few globals used by verifier */
6408         mutex_lock(&bpf_verifier_lock);
6409 
6410         if (attr->log_level || attr->log_buf || attr->log_size) {
6411                 /* user requested verbose verifier output
6412                  * and supplied buffer to store the verification trace
6413                  */
6414                 log->level = attr->log_level;
6415                 log->ubuf = (char __user *) (unsigned long) attr->log_buf;
6416                 log->len_total = attr->log_size;
6417 
6418                 ret = -EINVAL;
6419                 /* log attributes have to be sane */
6420                 if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 ||
6421                     !log->level || !log->ubuf)
6422                         goto err_unlock;
6423         }
6424 
6425         env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
6426         if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
6427                 env->strict_alignment = true;
6428 
6429         ret = replace_map_fd_with_map_ptr(env);
6430         if (ret < 0)
6431                 goto skip_full_check;
6432 
6433         if (bpf_prog_is_dev_bound(env->prog->aux)) {
6434                 ret = bpf_prog_offload_verifier_prep(env);
6435                 if (ret)
6436                         goto skip_full_check;
6437         }
6438 
6439         env->explored_states = kcalloc(env->prog->len,
6440                                        sizeof(struct bpf_verifier_state_list *),
6441                                        GFP_USER);
6442         ret = -ENOMEM;
6443         if (!env->explored_states)
6444                 goto skip_full_check;
6445 
6446         env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
6447 
6448         ret = check_cfg(env);
6449         if (ret < 0)
6450                 goto skip_full_check;
6451 
6452         ret = do_check(env);
6453         if (env->cur_state) {
6454                 free_verifier_state(env->cur_state, true);
6455                 env->cur_state = NULL;
6456         }
6457 
6458         if (ret == 0 && bpf_prog_is_dev_bound(env->prog->aux))
6459                 ret = bpf_prog_offload_finalize(env);
6460 
6461 skip_full_check:
6462         while (!pop_stack(env, NULL, NULL));
6463         free_states(env);
6464 
6465         if (ret == 0)
6466                 sanitize_dead_code(env);
6467 
6468         if (ret == 0)
6469                 ret = check_max_stack_depth(env);
6470 
6471         if (ret == 0)
6472                 /* program is valid, convert *(u32*)(ctx + off) accesses */
6473                 ret = convert_ctx_accesses(env);
6474 
6475         if (ret == 0)
6476                 ret = fixup_bpf_calls(env);
6477 
6478         if (ret == 0)
6479                 ret = fixup_call_args(env);
6480 
6481         if (log->level && bpf_verifier_log_full(log))
6482                 ret = -ENOSPC;
6483         if (log->level && !log->ubuf) {
6484                 ret = -EFAULT;
6485                 goto err_release_maps;
6486         }
6487 
6488         if (ret == 0 && env->used_map_cnt) {
6489                 /* if program passed verifier, update used_maps in bpf_prog_info */
6490                 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
6491                                                           sizeof(env->used_maps[0]),
6492                                                           GFP_KERNEL);
6493 
6494                 if (!env->prog->aux->used_maps) {
6495                         ret = -ENOMEM;
6496                         goto err_release_maps;
6497                 }
6498 
6499                 memcpy(env->prog->aux->used_maps, env->used_maps,
6500                        sizeof(env->used_maps[0]) * env->used_map_cnt);
6501                 env->prog->aux->used_map_cnt = env->used_map_cnt;
6502 
6503                 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
6504                  * bpf_ld_imm64 instructions
6505                  */
6506                 convert_pseudo_ld_imm64(env);
6507         }
6508 
6509 err_release_maps:
6510         if (!env->prog->aux->used_maps)
6511                 /* if we didn't copy map pointers into bpf_prog_info, release
6512                  * them now. Otherwise free_used_maps() will release them.
6513                  */
6514                 release_maps(env);
6515         *prog = env->prog;
6516 err_unlock:
6517         mutex_unlock(&bpf_verifier_lock);
6518         vfree(env->insn_aux_data);
6519 err_free_env:
6520         kfree(env);
6521         return ret;
6522 }
6523 

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