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TOMOYO Linux Cross Reference
Linux/kernel/trace/bpf_trace.c

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  1 /* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
  2  * Copyright (c) 2016 Facebook
  3  *
  4  * This program is free software; you can redistribute it and/or
  5  * modify it under the terms of version 2 of the GNU General Public
  6  * License as published by the Free Software Foundation.
  7  */
  8 #include <linux/kernel.h>
  9 #include <linux/types.h>
 10 #include <linux/slab.h>
 11 #include <linux/bpf.h>
 12 #include <linux/bpf_perf_event.h>
 13 #include <linux/filter.h>
 14 #include <linux/uaccess.h>
 15 #include <linux/ctype.h>
 16 #include <linux/kprobes.h>
 17 #include <linux/error-injection.h>
 18 
 19 #include "trace_probe.h"
 20 #include "trace.h"
 21 
 22 u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 23 
 24 /**
 25  * trace_call_bpf - invoke BPF program
 26  * @call: tracepoint event
 27  * @ctx: opaque context pointer
 28  *
 29  * kprobe handlers execute BPF programs via this helper.
 30  * Can be used from static tracepoints in the future.
 31  *
 32  * Return: BPF programs always return an integer which is interpreted by
 33  * kprobe handler as:
 34  * 0 - return from kprobe (event is filtered out)
 35  * 1 - store kprobe event into ring buffer
 36  * Other values are reserved and currently alias to 1
 37  */
 38 unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
 39 {
 40         unsigned int ret;
 41 
 42         if (in_nmi()) /* not supported yet */
 43                 return 1;
 44 
 45         preempt_disable();
 46 
 47         if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
 48                 /*
 49                  * since some bpf program is already running on this cpu,
 50                  * don't call into another bpf program (same or different)
 51                  * and don't send kprobe event into ring-buffer,
 52                  * so return zero here
 53                  */
 54                 ret = 0;
 55                 goto out;
 56         }
 57 
 58         /*
 59          * Instead of moving rcu_read_lock/rcu_dereference/rcu_read_unlock
 60          * to all call sites, we did a bpf_prog_array_valid() there to check
 61          * whether call->prog_array is empty or not, which is
 62          * a heurisitc to speed up execution.
 63          *
 64          * If bpf_prog_array_valid() fetched prog_array was
 65          * non-NULL, we go into trace_call_bpf() and do the actual
 66          * proper rcu_dereference() under RCU lock.
 67          * If it turns out that prog_array is NULL then, we bail out.
 68          * For the opposite, if the bpf_prog_array_valid() fetched pointer
 69          * was NULL, you'll skip the prog_array with the risk of missing
 70          * out of events when it was updated in between this and the
 71          * rcu_dereference() which is accepted risk.
 72          */
 73         ret = BPF_PROG_RUN_ARRAY_CHECK(call->prog_array, ctx, BPF_PROG_RUN);
 74 
 75  out:
 76         __this_cpu_dec(bpf_prog_active);
 77         preempt_enable();
 78 
 79         return ret;
 80 }
 81 EXPORT_SYMBOL_GPL(trace_call_bpf);
 82 
 83 #ifdef CONFIG_BPF_KPROBE_OVERRIDE
 84 BPF_CALL_2(bpf_override_return, struct pt_regs *, regs, unsigned long, rc)
 85 {
 86         regs_set_return_value(regs, rc);
 87         override_function_with_return(regs);
 88         return 0;
 89 }
 90 
 91 static const struct bpf_func_proto bpf_override_return_proto = {
 92         .func           = bpf_override_return,
 93         .gpl_only       = true,
 94         .ret_type       = RET_INTEGER,
 95         .arg1_type      = ARG_PTR_TO_CTX,
 96         .arg2_type      = ARG_ANYTHING,
 97 };
 98 #endif
 99 
100 BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
101 {
102         int ret;
103 
104         ret = probe_kernel_read(dst, unsafe_ptr, size);
105         if (unlikely(ret < 0))
106                 memset(dst, 0, size);
107 
108         return ret;
109 }
110 
111 static const struct bpf_func_proto bpf_probe_read_proto = {
112         .func           = bpf_probe_read,
113         .gpl_only       = true,
114         .ret_type       = RET_INTEGER,
115         .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
116         .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
117         .arg3_type      = ARG_ANYTHING,
118 };
119 
120 BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src,
121            u32, size)
122 {
123         /*
124          * Ensure we're in user context which is safe for the helper to
125          * run. This helper has no business in a kthread.
126          *
127          * access_ok() should prevent writing to non-user memory, but in
128          * some situations (nommu, temporary switch, etc) access_ok() does
129          * not provide enough validation, hence the check on KERNEL_DS.
130          */
131 
132         if (unlikely(in_interrupt() ||
133                      current->flags & (PF_KTHREAD | PF_EXITING)))
134                 return -EPERM;
135         if (unlikely(uaccess_kernel()))
136                 return -EPERM;
137         if (!access_ok(VERIFY_WRITE, unsafe_ptr, size))
138                 return -EPERM;
139 
140         return probe_kernel_write(unsafe_ptr, src, size);
141 }
142 
143 static const struct bpf_func_proto bpf_probe_write_user_proto = {
144         .func           = bpf_probe_write_user,
145         .gpl_only       = true,
146         .ret_type       = RET_INTEGER,
147         .arg1_type      = ARG_ANYTHING,
148         .arg2_type      = ARG_PTR_TO_MEM,
149         .arg3_type      = ARG_CONST_SIZE,
150 };
151 
152 static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
153 {
154         pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!",
155                             current->comm, task_pid_nr(current));
156 
157         return &bpf_probe_write_user_proto;
158 }
159 
160 /*
161  * Only limited trace_printk() conversion specifiers allowed:
162  * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %s
163  */
164 BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
165            u64, arg2, u64, arg3)
166 {
167         bool str_seen = false;
168         int mod[3] = {};
169         int fmt_cnt = 0;
170         u64 unsafe_addr;
171         char buf[64];
172         int i;
173 
174         /*
175          * bpf_check()->check_func_arg()->check_stack_boundary()
176          * guarantees that fmt points to bpf program stack,
177          * fmt_size bytes of it were initialized and fmt_size > 0
178          */
179         if (fmt[--fmt_size] != 0)
180                 return -EINVAL;
181 
182         /* check format string for allowed specifiers */
183         for (i = 0; i < fmt_size; i++) {
184                 if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i]))
185                         return -EINVAL;
186 
187                 if (fmt[i] != '%')
188                         continue;
189 
190                 if (fmt_cnt >= 3)
191                         return -EINVAL;
192 
193                 /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
194                 i++;
195                 if (fmt[i] == 'l') {
196                         mod[fmt_cnt]++;
197                         i++;
198                 } else if (fmt[i] == 'p' || fmt[i] == 's') {
199                         mod[fmt_cnt]++;
200                         i++;
201                         if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
202                                 return -EINVAL;
203                         fmt_cnt++;
204                         if (fmt[i - 1] == 's') {
205                                 if (str_seen)
206                                         /* allow only one '%s' per fmt string */
207                                         return -EINVAL;
208                                 str_seen = true;
209 
210                                 switch (fmt_cnt) {
211                                 case 1:
212                                         unsafe_addr = arg1;
213                                         arg1 = (long) buf;
214                                         break;
215                                 case 2:
216                                         unsafe_addr = arg2;
217                                         arg2 = (long) buf;
218                                         break;
219                                 case 3:
220                                         unsafe_addr = arg3;
221                                         arg3 = (long) buf;
222                                         break;
223                                 }
224                                 buf[0] = 0;
225                                 strncpy_from_unsafe(buf,
226                                                     (void *) (long) unsafe_addr,
227                                                     sizeof(buf));
228                         }
229                         continue;
230                 }
231 
232                 if (fmt[i] == 'l') {
233                         mod[fmt_cnt]++;
234                         i++;
235                 }
236 
237                 if (fmt[i] != 'i' && fmt[i] != 'd' &&
238                     fmt[i] != 'u' && fmt[i] != 'x')
239                         return -EINVAL;
240                 fmt_cnt++;
241         }
242 
243 /* Horrid workaround for getting va_list handling working with different
244  * argument type combinations generically for 32 and 64 bit archs.
245  */
246 #define __BPF_TP_EMIT() __BPF_ARG3_TP()
247 #define __BPF_TP(...)                                                   \
248         __trace_printk(0 /* Fake ip */,                                 \
249                        fmt, ##__VA_ARGS__)
250 
251 #define __BPF_ARG1_TP(...)                                              \
252         ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64))        \
253           ? __BPF_TP(arg1, ##__VA_ARGS__)                               \
254           : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32))    \
255               ? __BPF_TP((long)arg1, ##__VA_ARGS__)                     \
256               : __BPF_TP((u32)arg1, ##__VA_ARGS__)))
257 
258 #define __BPF_ARG2_TP(...)                                              \
259         ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64))        \
260           ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__)                          \
261           : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32))    \
262               ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__)                \
263               : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__)))
264 
265 #define __BPF_ARG3_TP(...)                                              \
266         ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64))        \
267           ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__)                          \
268           : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32))    \
269               ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__)                \
270               : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__)))
271 
272         return __BPF_TP_EMIT();
273 }
274 
275 static const struct bpf_func_proto bpf_trace_printk_proto = {
276         .func           = bpf_trace_printk,
277         .gpl_only       = true,
278         .ret_type       = RET_INTEGER,
279         .arg1_type      = ARG_PTR_TO_MEM,
280         .arg2_type      = ARG_CONST_SIZE,
281 };
282 
283 const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
284 {
285         /*
286          * this program might be calling bpf_trace_printk,
287          * so allocate per-cpu printk buffers
288          */
289         trace_printk_init_buffers();
290 
291         return &bpf_trace_printk_proto;
292 }
293 
294 static __always_inline int
295 get_map_perf_counter(struct bpf_map *map, u64 flags,
296                      u64 *value, u64 *enabled, u64 *running)
297 {
298         struct bpf_array *array = container_of(map, struct bpf_array, map);
299         unsigned int cpu = smp_processor_id();
300         u64 index = flags & BPF_F_INDEX_MASK;
301         struct bpf_event_entry *ee;
302 
303         if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
304                 return -EINVAL;
305         if (index == BPF_F_CURRENT_CPU)
306                 index = cpu;
307         if (unlikely(index >= array->map.max_entries))
308                 return -E2BIG;
309 
310         ee = READ_ONCE(array->ptrs[index]);
311         if (!ee)
312                 return -ENOENT;
313 
314         return perf_event_read_local(ee->event, value, enabled, running);
315 }
316 
317 BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
318 {
319         u64 value = 0;
320         int err;
321 
322         err = get_map_perf_counter(map, flags, &value, NULL, NULL);
323         /*
324          * this api is ugly since we miss [-22..-2] range of valid
325          * counter values, but that's uapi
326          */
327         if (err)
328                 return err;
329         return value;
330 }
331 
332 static const struct bpf_func_proto bpf_perf_event_read_proto = {
333         .func           = bpf_perf_event_read,
334         .gpl_only       = true,
335         .ret_type       = RET_INTEGER,
336         .arg1_type      = ARG_CONST_MAP_PTR,
337         .arg2_type      = ARG_ANYTHING,
338 };
339 
340 BPF_CALL_4(bpf_perf_event_read_value, struct bpf_map *, map, u64, flags,
341            struct bpf_perf_event_value *, buf, u32, size)
342 {
343         int err = -EINVAL;
344 
345         if (unlikely(size != sizeof(struct bpf_perf_event_value)))
346                 goto clear;
347         err = get_map_perf_counter(map, flags, &buf->counter, &buf->enabled,
348                                    &buf->running);
349         if (unlikely(err))
350                 goto clear;
351         return 0;
352 clear:
353         memset(buf, 0, size);
354         return err;
355 }
356 
357 static const struct bpf_func_proto bpf_perf_event_read_value_proto = {
358         .func           = bpf_perf_event_read_value,
359         .gpl_only       = true,
360         .ret_type       = RET_INTEGER,
361         .arg1_type      = ARG_CONST_MAP_PTR,
362         .arg2_type      = ARG_ANYTHING,
363         .arg3_type      = ARG_PTR_TO_UNINIT_MEM,
364         .arg4_type      = ARG_CONST_SIZE,
365 };
366 
367 static DEFINE_PER_CPU(struct perf_sample_data, bpf_trace_sd);
368 
369 static __always_inline u64
370 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
371                         u64 flags, struct perf_sample_data *sd)
372 {
373         struct bpf_array *array = container_of(map, struct bpf_array, map);
374         unsigned int cpu = smp_processor_id();
375         u64 index = flags & BPF_F_INDEX_MASK;
376         struct bpf_event_entry *ee;
377         struct perf_event *event;
378 
379         if (index == BPF_F_CURRENT_CPU)
380                 index = cpu;
381         if (unlikely(index >= array->map.max_entries))
382                 return -E2BIG;
383 
384         ee = READ_ONCE(array->ptrs[index]);
385         if (!ee)
386                 return -ENOENT;
387 
388         event = ee->event;
389         if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
390                      event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
391                 return -EINVAL;
392 
393         if (unlikely(event->oncpu != cpu))
394                 return -EOPNOTSUPP;
395 
396         perf_event_output(event, sd, regs);
397         return 0;
398 }
399 
400 BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
401            u64, flags, void *, data, u64, size)
402 {
403         struct perf_sample_data *sd = this_cpu_ptr(&bpf_trace_sd);
404         struct perf_raw_record raw = {
405                 .frag = {
406                         .size = size,
407                         .data = data,
408                 },
409         };
410 
411         if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
412                 return -EINVAL;
413 
414         perf_sample_data_init(sd, 0, 0);
415         sd->raw = &raw;
416 
417         return __bpf_perf_event_output(regs, map, flags, sd);
418 }
419 
420 static const struct bpf_func_proto bpf_perf_event_output_proto = {
421         .func           = bpf_perf_event_output,
422         .gpl_only       = true,
423         .ret_type       = RET_INTEGER,
424         .arg1_type      = ARG_PTR_TO_CTX,
425         .arg2_type      = ARG_CONST_MAP_PTR,
426         .arg3_type      = ARG_ANYTHING,
427         .arg4_type      = ARG_PTR_TO_MEM,
428         .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
429 };
430 
431 static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
432 static DEFINE_PER_CPU(struct perf_sample_data, bpf_misc_sd);
433 
434 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
435                      void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
436 {
437         struct perf_sample_data *sd = this_cpu_ptr(&bpf_misc_sd);
438         struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
439         struct perf_raw_frag frag = {
440                 .copy           = ctx_copy,
441                 .size           = ctx_size,
442                 .data           = ctx,
443         };
444         struct perf_raw_record raw = {
445                 .frag = {
446                         {
447                                 .next   = ctx_size ? &frag : NULL,
448                         },
449                         .size   = meta_size,
450                         .data   = meta,
451                 },
452         };
453 
454         perf_fetch_caller_regs(regs);
455         perf_sample_data_init(sd, 0, 0);
456         sd->raw = &raw;
457 
458         return __bpf_perf_event_output(regs, map, flags, sd);
459 }
460 
461 BPF_CALL_0(bpf_get_current_task)
462 {
463         return (long) current;
464 }
465 
466 static const struct bpf_func_proto bpf_get_current_task_proto = {
467         .func           = bpf_get_current_task,
468         .gpl_only       = true,
469         .ret_type       = RET_INTEGER,
470 };
471 
472 BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
473 {
474         struct bpf_array *array = container_of(map, struct bpf_array, map);
475         struct cgroup *cgrp;
476 
477         if (unlikely(in_interrupt()))
478                 return -EINVAL;
479         if (unlikely(idx >= array->map.max_entries))
480                 return -E2BIG;
481 
482         cgrp = READ_ONCE(array->ptrs[idx]);
483         if (unlikely(!cgrp))
484                 return -EAGAIN;
485 
486         return task_under_cgroup_hierarchy(current, cgrp);
487 }
488 
489 static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
490         .func           = bpf_current_task_under_cgroup,
491         .gpl_only       = false,
492         .ret_type       = RET_INTEGER,
493         .arg1_type      = ARG_CONST_MAP_PTR,
494         .arg2_type      = ARG_ANYTHING,
495 };
496 
497 BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
498            const void *, unsafe_ptr)
499 {
500         int ret;
501 
502         /*
503          * The strncpy_from_unsafe() call will likely not fill the entire
504          * buffer, but that's okay in this circumstance as we're probing
505          * arbitrary memory anyway similar to bpf_probe_read() and might
506          * as well probe the stack. Thus, memory is explicitly cleared
507          * only in error case, so that improper users ignoring return
508          * code altogether don't copy garbage; otherwise length of string
509          * is returned that can be used for bpf_perf_event_output() et al.
510          */
511         ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
512         if (unlikely(ret < 0))
513                 memset(dst, 0, size);
514 
515         return ret;
516 }
517 
518 static const struct bpf_func_proto bpf_probe_read_str_proto = {
519         .func           = bpf_probe_read_str,
520         .gpl_only       = true,
521         .ret_type       = RET_INTEGER,
522         .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
523         .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
524         .arg3_type      = ARG_ANYTHING,
525 };
526 
527 static const struct bpf_func_proto *
528 tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
529 {
530         switch (func_id) {
531         case BPF_FUNC_map_lookup_elem:
532                 return &bpf_map_lookup_elem_proto;
533         case BPF_FUNC_map_update_elem:
534                 return &bpf_map_update_elem_proto;
535         case BPF_FUNC_map_delete_elem:
536                 return &bpf_map_delete_elem_proto;
537         case BPF_FUNC_probe_read:
538                 return &bpf_probe_read_proto;
539         case BPF_FUNC_ktime_get_ns:
540                 return &bpf_ktime_get_ns_proto;
541         case BPF_FUNC_tail_call:
542                 return &bpf_tail_call_proto;
543         case BPF_FUNC_get_current_pid_tgid:
544                 return &bpf_get_current_pid_tgid_proto;
545         case BPF_FUNC_get_current_task:
546                 return &bpf_get_current_task_proto;
547         case BPF_FUNC_get_current_uid_gid:
548                 return &bpf_get_current_uid_gid_proto;
549         case BPF_FUNC_get_current_comm:
550                 return &bpf_get_current_comm_proto;
551         case BPF_FUNC_trace_printk:
552                 return bpf_get_trace_printk_proto();
553         case BPF_FUNC_get_smp_processor_id:
554                 return &bpf_get_smp_processor_id_proto;
555         case BPF_FUNC_get_numa_node_id:
556                 return &bpf_get_numa_node_id_proto;
557         case BPF_FUNC_perf_event_read:
558                 return &bpf_perf_event_read_proto;
559         case BPF_FUNC_probe_write_user:
560                 return bpf_get_probe_write_proto();
561         case BPF_FUNC_current_task_under_cgroup:
562                 return &bpf_current_task_under_cgroup_proto;
563         case BPF_FUNC_get_prandom_u32:
564                 return &bpf_get_prandom_u32_proto;
565         case BPF_FUNC_probe_read_str:
566                 return &bpf_probe_read_str_proto;
567         default:
568                 return NULL;
569         }
570 }
571 
572 static const struct bpf_func_proto *
573 kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
574 {
575         switch (func_id) {
576         case BPF_FUNC_perf_event_output:
577                 return &bpf_perf_event_output_proto;
578         case BPF_FUNC_get_stackid:
579                 return &bpf_get_stackid_proto;
580         case BPF_FUNC_perf_event_read_value:
581                 return &bpf_perf_event_read_value_proto;
582 #ifdef CONFIG_BPF_KPROBE_OVERRIDE
583         case BPF_FUNC_override_return:
584                 return &bpf_override_return_proto;
585 #endif
586         default:
587                 return tracing_func_proto(func_id, prog);
588         }
589 }
590 
591 /* bpf+kprobe programs can access fields of 'struct pt_regs' */
592 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
593                                         const struct bpf_prog *prog,
594                                         struct bpf_insn_access_aux *info)
595 {
596         if (off < 0 || off >= sizeof(struct pt_regs))
597                 return false;
598         if (type != BPF_READ)
599                 return false;
600         if (off % size != 0)
601                 return false;
602         /*
603          * Assertion for 32 bit to make sure last 8 byte access
604          * (BPF_DW) to the last 4 byte member is disallowed.
605          */
606         if (off + size > sizeof(struct pt_regs))
607                 return false;
608 
609         return true;
610 }
611 
612 const struct bpf_verifier_ops kprobe_verifier_ops = {
613         .get_func_proto  = kprobe_prog_func_proto,
614         .is_valid_access = kprobe_prog_is_valid_access,
615 };
616 
617 const struct bpf_prog_ops kprobe_prog_ops = {
618 };
619 
620 BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map,
621            u64, flags, void *, data, u64, size)
622 {
623         struct pt_regs *regs = *(struct pt_regs **)tp_buff;
624 
625         /*
626          * r1 points to perf tracepoint buffer where first 8 bytes are hidden
627          * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
628          * from there and call the same bpf_perf_event_output() helper inline.
629          */
630         return ____bpf_perf_event_output(regs, map, flags, data, size);
631 }
632 
633 static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
634         .func           = bpf_perf_event_output_tp,
635         .gpl_only       = true,
636         .ret_type       = RET_INTEGER,
637         .arg1_type      = ARG_PTR_TO_CTX,
638         .arg2_type      = ARG_CONST_MAP_PTR,
639         .arg3_type      = ARG_ANYTHING,
640         .arg4_type      = ARG_PTR_TO_MEM,
641         .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
642 };
643 
644 BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
645            u64, flags)
646 {
647         struct pt_regs *regs = *(struct pt_regs **)tp_buff;
648 
649         /*
650          * Same comment as in bpf_perf_event_output_tp(), only that this time
651          * the other helper's function body cannot be inlined due to being
652          * external, thus we need to call raw helper function.
653          */
654         return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
655                                flags, 0, 0);
656 }
657 
658 static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
659         .func           = bpf_get_stackid_tp,
660         .gpl_only       = true,
661         .ret_type       = RET_INTEGER,
662         .arg1_type      = ARG_PTR_TO_CTX,
663         .arg2_type      = ARG_CONST_MAP_PTR,
664         .arg3_type      = ARG_ANYTHING,
665 };
666 
667 static const struct bpf_func_proto *
668 tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
669 {
670         switch (func_id) {
671         case BPF_FUNC_perf_event_output:
672                 return &bpf_perf_event_output_proto_tp;
673         case BPF_FUNC_get_stackid:
674                 return &bpf_get_stackid_proto_tp;
675         default:
676                 return tracing_func_proto(func_id, prog);
677         }
678 }
679 
680 static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
681                                     const struct bpf_prog *prog,
682                                     struct bpf_insn_access_aux *info)
683 {
684         if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
685                 return false;
686         if (type != BPF_READ)
687                 return false;
688         if (off % size != 0)
689                 return false;
690 
691         BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));
692         return true;
693 }
694 
695 const struct bpf_verifier_ops tracepoint_verifier_ops = {
696         .get_func_proto  = tp_prog_func_proto,
697         .is_valid_access = tp_prog_is_valid_access,
698 };
699 
700 const struct bpf_prog_ops tracepoint_prog_ops = {
701 };
702 
703 BPF_CALL_3(bpf_perf_prog_read_value, struct bpf_perf_event_data_kern *, ctx,
704            struct bpf_perf_event_value *, buf, u32, size)
705 {
706         int err = -EINVAL;
707 
708         if (unlikely(size != sizeof(struct bpf_perf_event_value)))
709                 goto clear;
710         err = perf_event_read_local(ctx->event, &buf->counter, &buf->enabled,
711                                     &buf->running);
712         if (unlikely(err))
713                 goto clear;
714         return 0;
715 clear:
716         memset(buf, 0, size);
717         return err;
718 }
719 
720 static const struct bpf_func_proto bpf_perf_prog_read_value_proto = {
721          .func           = bpf_perf_prog_read_value,
722          .gpl_only       = true,
723          .ret_type       = RET_INTEGER,
724          .arg1_type      = ARG_PTR_TO_CTX,
725          .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
726          .arg3_type      = ARG_CONST_SIZE,
727 };
728 
729 static const struct bpf_func_proto *
730 pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
731 {
732         switch (func_id) {
733         case BPF_FUNC_perf_event_output:
734                 return &bpf_perf_event_output_proto_tp;
735         case BPF_FUNC_get_stackid:
736                 return &bpf_get_stackid_proto_tp;
737         case BPF_FUNC_perf_prog_read_value:
738                 return &bpf_perf_prog_read_value_proto;
739         default:
740                 return tracing_func_proto(func_id, prog);
741         }
742 }
743 
744 /*
745  * bpf_raw_tp_regs are separate from bpf_pt_regs used from skb/xdp
746  * to avoid potential recursive reuse issue when/if tracepoints are added
747  * inside bpf_*_event_output and/or bpf_get_stack_id
748  */
749 static DEFINE_PER_CPU(struct pt_regs, bpf_raw_tp_regs);
750 BPF_CALL_5(bpf_perf_event_output_raw_tp, struct bpf_raw_tracepoint_args *, args,
751            struct bpf_map *, map, u64, flags, void *, data, u64, size)
752 {
753         struct pt_regs *regs = this_cpu_ptr(&bpf_raw_tp_regs);
754 
755         perf_fetch_caller_regs(regs);
756         return ____bpf_perf_event_output(regs, map, flags, data, size);
757 }
758 
759 static const struct bpf_func_proto bpf_perf_event_output_proto_raw_tp = {
760         .func           = bpf_perf_event_output_raw_tp,
761         .gpl_only       = true,
762         .ret_type       = RET_INTEGER,
763         .arg1_type      = ARG_PTR_TO_CTX,
764         .arg2_type      = ARG_CONST_MAP_PTR,
765         .arg3_type      = ARG_ANYTHING,
766         .arg4_type      = ARG_PTR_TO_MEM,
767         .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
768 };
769 
770 BPF_CALL_3(bpf_get_stackid_raw_tp, struct bpf_raw_tracepoint_args *, args,
771            struct bpf_map *, map, u64, flags)
772 {
773         struct pt_regs *regs = this_cpu_ptr(&bpf_raw_tp_regs);
774 
775         perf_fetch_caller_regs(regs);
776         /* similar to bpf_perf_event_output_tp, but pt_regs fetched differently */
777         return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
778                                flags, 0, 0);
779 }
780 
781 static const struct bpf_func_proto bpf_get_stackid_proto_raw_tp = {
782         .func           = bpf_get_stackid_raw_tp,
783         .gpl_only       = true,
784         .ret_type       = RET_INTEGER,
785         .arg1_type      = ARG_PTR_TO_CTX,
786         .arg2_type      = ARG_CONST_MAP_PTR,
787         .arg3_type      = ARG_ANYTHING,
788 };
789 
790 static const struct bpf_func_proto *
791 raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
792 {
793         switch (func_id) {
794         case BPF_FUNC_perf_event_output:
795                 return &bpf_perf_event_output_proto_raw_tp;
796         case BPF_FUNC_get_stackid:
797                 return &bpf_get_stackid_proto_raw_tp;
798         default:
799                 return tracing_func_proto(func_id, prog);
800         }
801 }
802 
803 static bool raw_tp_prog_is_valid_access(int off, int size,
804                                         enum bpf_access_type type,
805                                         const struct bpf_prog *prog,
806                                         struct bpf_insn_access_aux *info)
807 {
808         /* largest tracepoint in the kernel has 12 args */
809         if (off < 0 || off >= sizeof(__u64) * 12)
810                 return false;
811         if (type != BPF_READ)
812                 return false;
813         if (off % size != 0)
814                 return false;
815         return true;
816 }
817 
818 const struct bpf_verifier_ops raw_tracepoint_verifier_ops = {
819         .get_func_proto  = raw_tp_prog_func_proto,
820         .is_valid_access = raw_tp_prog_is_valid_access,
821 };
822 
823 const struct bpf_prog_ops raw_tracepoint_prog_ops = {
824 };
825 
826 static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
827                                     const struct bpf_prog *prog,
828                                     struct bpf_insn_access_aux *info)
829 {
830         const int size_u64 = sizeof(u64);
831 
832         if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
833                 return false;
834         if (type != BPF_READ)
835                 return false;
836         if (off % size != 0)
837                 return false;
838 
839         switch (off) {
840         case bpf_ctx_range(struct bpf_perf_event_data, sample_period):
841                 bpf_ctx_record_field_size(info, size_u64);
842                 if (!bpf_ctx_narrow_access_ok(off, size, size_u64))
843                         return false;
844                 break;
845         case bpf_ctx_range(struct bpf_perf_event_data, addr):
846                 bpf_ctx_record_field_size(info, size_u64);
847                 if (!bpf_ctx_narrow_access_ok(off, size, size_u64))
848                         return false;
849                 break;
850         default:
851                 if (size != sizeof(long))
852                         return false;
853         }
854 
855         return true;
856 }
857 
858 static u32 pe_prog_convert_ctx_access(enum bpf_access_type type,
859                                       const struct bpf_insn *si,
860                                       struct bpf_insn *insn_buf,
861                                       struct bpf_prog *prog, u32 *target_size)
862 {
863         struct bpf_insn *insn = insn_buf;
864 
865         switch (si->off) {
866         case offsetof(struct bpf_perf_event_data, sample_period):
867                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
868                                                        data), si->dst_reg, si->src_reg,
869                                       offsetof(struct bpf_perf_event_data_kern, data));
870                 *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
871                                       bpf_target_off(struct perf_sample_data, period, 8,
872                                                      target_size));
873                 break;
874         case offsetof(struct bpf_perf_event_data, addr):
875                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
876                                                        data), si->dst_reg, si->src_reg,
877                                       offsetof(struct bpf_perf_event_data_kern, data));
878                 *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
879                                       bpf_target_off(struct perf_sample_data, addr, 8,
880                                                      target_size));
881                 break;
882         default:
883                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
884                                                        regs), si->dst_reg, si->src_reg,
885                                       offsetof(struct bpf_perf_event_data_kern, regs));
886                 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), si->dst_reg, si->dst_reg,
887                                       si->off);
888                 break;
889         }
890 
891         return insn - insn_buf;
892 }
893 
894 const struct bpf_verifier_ops perf_event_verifier_ops = {
895         .get_func_proto         = pe_prog_func_proto,
896         .is_valid_access        = pe_prog_is_valid_access,
897         .convert_ctx_access     = pe_prog_convert_ctx_access,
898 };
899 
900 const struct bpf_prog_ops perf_event_prog_ops = {
901 };
902 
903 static DEFINE_MUTEX(bpf_event_mutex);
904 
905 #define BPF_TRACE_MAX_PROGS 64
906 
907 int perf_event_attach_bpf_prog(struct perf_event *event,
908                                struct bpf_prog *prog)
909 {
910         struct bpf_prog_array __rcu *old_array;
911         struct bpf_prog_array *new_array;
912         int ret = -EEXIST;
913 
914         /*
915          * Kprobe override only works if they are on the function entry,
916          * and only if they are on the opt-in list.
917          */
918         if (prog->kprobe_override &&
919             (!trace_kprobe_on_func_entry(event->tp_event) ||
920              !trace_kprobe_error_injectable(event->tp_event)))
921                 return -EINVAL;
922 
923         mutex_lock(&bpf_event_mutex);
924 
925         if (event->prog)
926                 goto unlock;
927 
928         old_array = event->tp_event->prog_array;
929         if (old_array &&
930             bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {
931                 ret = -E2BIG;
932                 goto unlock;
933         }
934 
935         ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
936         if (ret < 0)
937                 goto unlock;
938 
939         /* set the new array to event->tp_event and set event->prog */
940         event->prog = prog;
941         rcu_assign_pointer(event->tp_event->prog_array, new_array);
942         bpf_prog_array_free(old_array);
943 
944 unlock:
945         mutex_unlock(&bpf_event_mutex);
946         return ret;
947 }
948 
949 void perf_event_detach_bpf_prog(struct perf_event *event)
950 {
951         struct bpf_prog_array __rcu *old_array;
952         struct bpf_prog_array *new_array;
953         int ret;
954 
955         mutex_lock(&bpf_event_mutex);
956 
957         if (!event->prog)
958                 goto unlock;
959 
960         old_array = event->tp_event->prog_array;
961         ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
962         if (ret < 0) {
963                 bpf_prog_array_delete_safe(old_array, event->prog);
964         } else {
965                 rcu_assign_pointer(event->tp_event->prog_array, new_array);
966                 bpf_prog_array_free(old_array);
967         }
968 
969         bpf_prog_put(event->prog);
970         event->prog = NULL;
971 
972 unlock:
973         mutex_unlock(&bpf_event_mutex);
974 }
975 
976 int perf_event_query_prog_array(struct perf_event *event, void __user *info)
977 {
978         struct perf_event_query_bpf __user *uquery = info;
979         struct perf_event_query_bpf query = {};
980         int ret;
981 
982         if (!capable(CAP_SYS_ADMIN))
983                 return -EPERM;
984         if (event->attr.type != PERF_TYPE_TRACEPOINT)
985                 return -EINVAL;
986         if (copy_from_user(&query, uquery, sizeof(query)))
987                 return -EFAULT;
988         if (query.ids_len > BPF_TRACE_MAX_PROGS)
989                 return -E2BIG;
990 
991         mutex_lock(&bpf_event_mutex);
992         ret = bpf_prog_array_copy_info(event->tp_event->prog_array,
993                                        uquery->ids,
994                                        query.ids_len,
995                                        &uquery->prog_cnt);
996         mutex_unlock(&bpf_event_mutex);
997 
998         return ret;
999 }
1000 
1001 extern struct bpf_raw_event_map __start__bpf_raw_tp[];
1002 extern struct bpf_raw_event_map __stop__bpf_raw_tp[];
1003 
1004 struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
1005 {
1006         struct bpf_raw_event_map *btp = __start__bpf_raw_tp;
1007 
1008         for (; btp < __stop__bpf_raw_tp; btp++) {
1009                 if (!strcmp(btp->tp->name, name))
1010                         return btp;
1011         }
1012         return NULL;
1013 }
1014 
1015 static __always_inline
1016 void __bpf_trace_run(struct bpf_prog *prog, u64 *args)
1017 {
1018         rcu_read_lock();
1019         preempt_disable();
1020         (void) BPF_PROG_RUN(prog, args);
1021         preempt_enable();
1022         rcu_read_unlock();
1023 }
1024 
1025 #define UNPACK(...)                     __VA_ARGS__
1026 #define REPEAT_1(FN, DL, X, ...)        FN(X)
1027 #define REPEAT_2(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_1(FN, DL, __VA_ARGS__)
1028 #define REPEAT_3(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_2(FN, DL, __VA_ARGS__)
1029 #define REPEAT_4(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_3(FN, DL, __VA_ARGS__)
1030 #define REPEAT_5(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_4(FN, DL, __VA_ARGS__)
1031 #define REPEAT_6(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_5(FN, DL, __VA_ARGS__)
1032 #define REPEAT_7(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_6(FN, DL, __VA_ARGS__)
1033 #define REPEAT_8(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_7(FN, DL, __VA_ARGS__)
1034 #define REPEAT_9(FN, DL, X, ...)        FN(X) UNPACK DL REPEAT_8(FN, DL, __VA_ARGS__)
1035 #define REPEAT_10(FN, DL, X, ...)       FN(X) UNPACK DL REPEAT_9(FN, DL, __VA_ARGS__)
1036 #define REPEAT_11(FN, DL, X, ...)       FN(X) UNPACK DL REPEAT_10(FN, DL, __VA_ARGS__)
1037 #define REPEAT_12(FN, DL, X, ...)       FN(X) UNPACK DL REPEAT_11(FN, DL, __VA_ARGS__)
1038 #define REPEAT(X, FN, DL, ...)          REPEAT_##X(FN, DL, __VA_ARGS__)
1039 
1040 #define SARG(X)         u64 arg##X
1041 #define COPY(X)         args[X] = arg##X
1042 
1043 #define __DL_COM        (,)
1044 #define __DL_SEM        (;)
1045 
1046 #define __SEQ_0_11      0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
1047 
1048 #define BPF_TRACE_DEFN_x(x)                                             \
1049         void bpf_trace_run##x(struct bpf_prog *prog,                    \
1050                               REPEAT(x, SARG, __DL_COM, __SEQ_0_11))    \
1051         {                                                               \
1052                 u64 args[x];                                            \
1053                 REPEAT(x, COPY, __DL_SEM, __SEQ_0_11);                  \
1054                 __bpf_trace_run(prog, args);                            \
1055         }                                                               \
1056         EXPORT_SYMBOL_GPL(bpf_trace_run##x)
1057 BPF_TRACE_DEFN_x(1);
1058 BPF_TRACE_DEFN_x(2);
1059 BPF_TRACE_DEFN_x(3);
1060 BPF_TRACE_DEFN_x(4);
1061 BPF_TRACE_DEFN_x(5);
1062 BPF_TRACE_DEFN_x(6);
1063 BPF_TRACE_DEFN_x(7);
1064 BPF_TRACE_DEFN_x(8);
1065 BPF_TRACE_DEFN_x(9);
1066 BPF_TRACE_DEFN_x(10);
1067 BPF_TRACE_DEFN_x(11);
1068 BPF_TRACE_DEFN_x(12);
1069 
1070 static int __bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
1071 {
1072         struct tracepoint *tp = btp->tp;
1073 
1074         /*
1075          * check that program doesn't access arguments beyond what's
1076          * available in this tracepoint
1077          */
1078         if (prog->aux->max_ctx_offset > btp->num_args * sizeof(u64))
1079                 return -EINVAL;
1080 
1081         return tracepoint_probe_register(tp, (void *)btp->bpf_func, prog);
1082 }
1083 
1084 int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
1085 {
1086         int err;
1087 
1088         mutex_lock(&bpf_event_mutex);
1089         err = __bpf_probe_register(btp, prog);
1090         mutex_unlock(&bpf_event_mutex);
1091         return err;
1092 }
1093 
1094 int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
1095 {
1096         int err;
1097 
1098         mutex_lock(&bpf_event_mutex);
1099         err = tracepoint_probe_unregister(btp->tp, (void *)btp->bpf_func, prog);
1100         mutex_unlock(&bpf_event_mutex);
1101         return err;
1102 }
1103 

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