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TOMOYO Linux Cross Reference
Linux/kernel/seccomp.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * linux/kernel/seccomp.c
  4  *
  5  * Copyright 2004-2005  Andrea Arcangeli <andrea@cpushare.com>
  6  *
  7  * Copyright (C) 2012 Google, Inc.
  8  * Will Drewry <wad@chromium.org>
  9  *
 10  * This defines a simple but solid secure-computing facility.
 11  *
 12  * Mode 1 uses a fixed list of allowed system calls.
 13  * Mode 2 allows user-defined system call filters in the form
 14  *        of Berkeley Packet Filters/Linux Socket Filters.
 15  */
 16 
 17 #include <linux/refcount.h>
 18 #include <linux/audit.h>
 19 #include <linux/compat.h>
 20 #include <linux/coredump.h>
 21 #include <linux/kmemleak.h>
 22 #include <linux/nospec.h>
 23 #include <linux/prctl.h>
 24 #include <linux/sched.h>
 25 #include <linux/sched/task_stack.h>
 26 #include <linux/seccomp.h>
 27 #include <linux/slab.h>
 28 #include <linux/syscalls.h>
 29 #include <linux/sysctl.h>
 30 
 31 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
 32 #include <asm/syscall.h>
 33 #endif
 34 
 35 #ifdef CONFIG_SECCOMP_FILTER
 36 #include <linux/file.h>
 37 #include <linux/filter.h>
 38 #include <linux/pid.h>
 39 #include <linux/ptrace.h>
 40 #include <linux/security.h>
 41 #include <linux/tracehook.h>
 42 #include <linux/uaccess.h>
 43 #include <linux/anon_inodes.h>
 44 
 45 enum notify_state {
 46         SECCOMP_NOTIFY_INIT,
 47         SECCOMP_NOTIFY_SENT,
 48         SECCOMP_NOTIFY_REPLIED,
 49 };
 50 
 51 struct seccomp_knotif {
 52         /* The struct pid of the task whose filter triggered the notification */
 53         struct task_struct *task;
 54 
 55         /* The "cookie" for this request; this is unique for this filter. */
 56         u64 id;
 57 
 58         /*
 59          * The seccomp data. This pointer is valid the entire time this
 60          * notification is active, since it comes from __seccomp_filter which
 61          * eclipses the entire lifecycle here.
 62          */
 63         const struct seccomp_data *data;
 64 
 65         /*
 66          * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
 67          * struct seccomp_knotif is created and starts out in INIT. Once the
 68          * handler reads the notification off of an FD, it transitions to SENT.
 69          * If a signal is received the state transitions back to INIT and
 70          * another message is sent. When the userspace handler replies, state
 71          * transitions to REPLIED.
 72          */
 73         enum notify_state state;
 74 
 75         /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
 76         int error;
 77         long val;
 78 
 79         /* Signals when this has entered SECCOMP_NOTIFY_REPLIED */
 80         struct completion ready;
 81 
 82         struct list_head list;
 83 };
 84 
 85 /**
 86  * struct notification - container for seccomp userspace notifications. Since
 87  * most seccomp filters will not have notification listeners attached and this
 88  * structure is fairly large, we store the notification-specific stuff in a
 89  * separate structure.
 90  *
 91  * @request: A semaphore that users of this notification can wait on for
 92  *           changes. Actual reads and writes are still controlled with
 93  *           filter->notify_lock.
 94  * @next_id: The id of the next request.
 95  * @notifications: A list of struct seccomp_knotif elements.
 96  * @wqh: A wait queue for poll.
 97  */
 98 struct notification {
 99         struct semaphore request;
100         u64 next_id;
101         struct list_head notifications;
102         wait_queue_head_t wqh;
103 };
104 
105 /**
106  * struct seccomp_filter - container for seccomp BPF programs
107  *
108  * @usage: reference count to manage the object lifetime.
109  *         get/put helpers should be used when accessing an instance
110  *         outside of a lifetime-guarded section.  In general, this
111  *         is only needed for handling filters shared across tasks.
112  * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
113  * @prev: points to a previously installed, or inherited, filter
114  * @prog: the BPF program to evaluate
115  * @notif: the struct that holds all notification related information
116  * @notify_lock: A lock for all notification-related accesses.
117  *
118  * seccomp_filter objects are organized in a tree linked via the @prev
119  * pointer.  For any task, it appears to be a singly-linked list starting
120  * with current->seccomp.filter, the most recently attached or inherited filter.
121  * However, multiple filters may share a @prev node, by way of fork(), which
122  * results in a unidirectional tree existing in memory.  This is similar to
123  * how namespaces work.
124  *
125  * seccomp_filter objects should never be modified after being attached
126  * to a task_struct (other than @usage).
127  */
128 struct seccomp_filter {
129         refcount_t usage;
130         bool log;
131         struct seccomp_filter *prev;
132         struct bpf_prog *prog;
133         struct notification *notif;
134         struct mutex notify_lock;
135 };
136 
137 /* Limit any path through the tree to 256KB worth of instructions. */
138 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
139 
140 /*
141  * Endianness is explicitly ignored and left for BPF program authors to manage
142  * as per the specific architecture.
143  */
144 static void populate_seccomp_data(struct seccomp_data *sd)
145 {
146         struct task_struct *task = current;
147         struct pt_regs *regs = task_pt_regs(task);
148         unsigned long args[6];
149 
150         sd->nr = syscall_get_nr(task, regs);
151         sd->arch = syscall_get_arch(task);
152         syscall_get_arguments(task, regs, args);
153         sd->args[0] = args[0];
154         sd->args[1] = args[1];
155         sd->args[2] = args[2];
156         sd->args[3] = args[3];
157         sd->args[4] = args[4];
158         sd->args[5] = args[5];
159         sd->instruction_pointer = KSTK_EIP(task);
160 }
161 
162 /**
163  *      seccomp_check_filter - verify seccomp filter code
164  *      @filter: filter to verify
165  *      @flen: length of filter
166  *
167  * Takes a previously checked filter (by bpf_check_classic) and
168  * redirects all filter code that loads struct sk_buff data
169  * and related data through seccomp_bpf_load.  It also
170  * enforces length and alignment checking of those loads.
171  *
172  * Returns 0 if the rule set is legal or -EINVAL if not.
173  */
174 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
175 {
176         int pc;
177         for (pc = 0; pc < flen; pc++) {
178                 struct sock_filter *ftest = &filter[pc];
179                 u16 code = ftest->code;
180                 u32 k = ftest->k;
181 
182                 switch (code) {
183                 case BPF_LD | BPF_W | BPF_ABS:
184                         ftest->code = BPF_LDX | BPF_W | BPF_ABS;
185                         /* 32-bit aligned and not out of bounds. */
186                         if (k >= sizeof(struct seccomp_data) || k & 3)
187                                 return -EINVAL;
188                         continue;
189                 case BPF_LD | BPF_W | BPF_LEN:
190                         ftest->code = BPF_LD | BPF_IMM;
191                         ftest->k = sizeof(struct seccomp_data);
192                         continue;
193                 case BPF_LDX | BPF_W | BPF_LEN:
194                         ftest->code = BPF_LDX | BPF_IMM;
195                         ftest->k = sizeof(struct seccomp_data);
196                         continue;
197                 /* Explicitly include allowed calls. */
198                 case BPF_RET | BPF_K:
199                 case BPF_RET | BPF_A:
200                 case BPF_ALU | BPF_ADD | BPF_K:
201                 case BPF_ALU | BPF_ADD | BPF_X:
202                 case BPF_ALU | BPF_SUB | BPF_K:
203                 case BPF_ALU | BPF_SUB | BPF_X:
204                 case BPF_ALU | BPF_MUL | BPF_K:
205                 case BPF_ALU | BPF_MUL | BPF_X:
206                 case BPF_ALU | BPF_DIV | BPF_K:
207                 case BPF_ALU | BPF_DIV | BPF_X:
208                 case BPF_ALU | BPF_AND | BPF_K:
209                 case BPF_ALU | BPF_AND | BPF_X:
210                 case BPF_ALU | BPF_OR | BPF_K:
211                 case BPF_ALU | BPF_OR | BPF_X:
212                 case BPF_ALU | BPF_XOR | BPF_K:
213                 case BPF_ALU | BPF_XOR | BPF_X:
214                 case BPF_ALU | BPF_LSH | BPF_K:
215                 case BPF_ALU | BPF_LSH | BPF_X:
216                 case BPF_ALU | BPF_RSH | BPF_K:
217                 case BPF_ALU | BPF_RSH | BPF_X:
218                 case BPF_ALU | BPF_NEG:
219                 case BPF_LD | BPF_IMM:
220                 case BPF_LDX | BPF_IMM:
221                 case BPF_MISC | BPF_TAX:
222                 case BPF_MISC | BPF_TXA:
223                 case BPF_LD | BPF_MEM:
224                 case BPF_LDX | BPF_MEM:
225                 case BPF_ST:
226                 case BPF_STX:
227                 case BPF_JMP | BPF_JA:
228                 case BPF_JMP | BPF_JEQ | BPF_K:
229                 case BPF_JMP | BPF_JEQ | BPF_X:
230                 case BPF_JMP | BPF_JGE | BPF_K:
231                 case BPF_JMP | BPF_JGE | BPF_X:
232                 case BPF_JMP | BPF_JGT | BPF_K:
233                 case BPF_JMP | BPF_JGT | BPF_X:
234                 case BPF_JMP | BPF_JSET | BPF_K:
235                 case BPF_JMP | BPF_JSET | BPF_X:
236                         continue;
237                 default:
238                         return -EINVAL;
239                 }
240         }
241         return 0;
242 }
243 
244 /**
245  * seccomp_run_filters - evaluates all seccomp filters against @sd
246  * @sd: optional seccomp data to be passed to filters
247  * @match: stores struct seccomp_filter that resulted in the return value,
248  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
249  *         be unchanged.
250  *
251  * Returns valid seccomp BPF response codes.
252  */
253 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
254 static u32 seccomp_run_filters(const struct seccomp_data *sd,
255                                struct seccomp_filter **match)
256 {
257         u32 ret = SECCOMP_RET_ALLOW;
258         /* Make sure cross-thread synced filter points somewhere sane. */
259         struct seccomp_filter *f =
260                         READ_ONCE(current->seccomp.filter);
261 
262         /* Ensure unexpected behavior doesn't result in failing open. */
263         if (WARN_ON(f == NULL))
264                 return SECCOMP_RET_KILL_PROCESS;
265 
266         /*
267          * All filters in the list are evaluated and the lowest BPF return
268          * value always takes priority (ignoring the DATA).
269          */
270         preempt_disable();
271         for (; f; f = f->prev) {
272                 u32 cur_ret = BPF_PROG_RUN(f->prog, sd);
273 
274                 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
275                         ret = cur_ret;
276                         *match = f;
277                 }
278         }
279         preempt_enable();
280         return ret;
281 }
282 #endif /* CONFIG_SECCOMP_FILTER */
283 
284 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
285 {
286         assert_spin_locked(&current->sighand->siglock);
287 
288         if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
289                 return false;
290 
291         return true;
292 }
293 
294 void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
295 
296 static inline void seccomp_assign_mode(struct task_struct *task,
297                                        unsigned long seccomp_mode,
298                                        unsigned long flags)
299 {
300         assert_spin_locked(&task->sighand->siglock);
301 
302         task->seccomp.mode = seccomp_mode;
303         /*
304          * Make sure TIF_SECCOMP cannot be set before the mode (and
305          * filter) is set.
306          */
307         smp_mb__before_atomic();
308         /* Assume default seccomp processes want spec flaw mitigation. */
309         if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
310                 arch_seccomp_spec_mitigate(task);
311         set_tsk_thread_flag(task, TIF_SECCOMP);
312 }
313 
314 #ifdef CONFIG_SECCOMP_FILTER
315 /* Returns 1 if the parent is an ancestor of the child. */
316 static int is_ancestor(struct seccomp_filter *parent,
317                        struct seccomp_filter *child)
318 {
319         /* NULL is the root ancestor. */
320         if (parent == NULL)
321                 return 1;
322         for (; child; child = child->prev)
323                 if (child == parent)
324                         return 1;
325         return 0;
326 }
327 
328 /**
329  * seccomp_can_sync_threads: checks if all threads can be synchronized
330  *
331  * Expects sighand and cred_guard_mutex locks to be held.
332  *
333  * Returns 0 on success, -ve on error, or the pid of a thread which was
334  * either not in the correct seccomp mode or did not have an ancestral
335  * seccomp filter.
336  */
337 static inline pid_t seccomp_can_sync_threads(void)
338 {
339         struct task_struct *thread, *caller;
340 
341         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
342         assert_spin_locked(&current->sighand->siglock);
343 
344         /* Validate all threads being eligible for synchronization. */
345         caller = current;
346         for_each_thread(caller, thread) {
347                 pid_t failed;
348 
349                 /* Skip current, since it is initiating the sync. */
350                 if (thread == caller)
351                         continue;
352 
353                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
354                     (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
355                      is_ancestor(thread->seccomp.filter,
356                                  caller->seccomp.filter)))
357                         continue;
358 
359                 /* Return the first thread that cannot be synchronized. */
360                 failed = task_pid_vnr(thread);
361                 /* If the pid cannot be resolved, then return -ESRCH */
362                 if (WARN_ON(failed == 0))
363                         failed = -ESRCH;
364                 return failed;
365         }
366 
367         return 0;
368 }
369 
370 /**
371  * seccomp_sync_threads: sets all threads to use current's filter
372  *
373  * Expects sighand and cred_guard_mutex locks to be held, and for
374  * seccomp_can_sync_threads() to have returned success already
375  * without dropping the locks.
376  *
377  */
378 static inline void seccomp_sync_threads(unsigned long flags)
379 {
380         struct task_struct *thread, *caller;
381 
382         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
383         assert_spin_locked(&current->sighand->siglock);
384 
385         /* Synchronize all threads. */
386         caller = current;
387         for_each_thread(caller, thread) {
388                 /* Skip current, since it needs no changes. */
389                 if (thread == caller)
390                         continue;
391 
392                 /* Get a task reference for the new leaf node. */
393                 get_seccomp_filter(caller);
394                 /*
395                  * Drop the task reference to the shared ancestor since
396                  * current's path will hold a reference.  (This also
397                  * allows a put before the assignment.)
398                  */
399                 put_seccomp_filter(thread);
400                 smp_store_release(&thread->seccomp.filter,
401                                   caller->seccomp.filter);
402 
403                 /*
404                  * Don't let an unprivileged task work around
405                  * the no_new_privs restriction by creating
406                  * a thread that sets it up, enters seccomp,
407                  * then dies.
408                  */
409                 if (task_no_new_privs(caller))
410                         task_set_no_new_privs(thread);
411 
412                 /*
413                  * Opt the other thread into seccomp if needed.
414                  * As threads are considered to be trust-realm
415                  * equivalent (see ptrace_may_access), it is safe to
416                  * allow one thread to transition the other.
417                  */
418                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
419                         seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
420                                             flags);
421         }
422 }
423 
424 /**
425  * seccomp_prepare_filter: Prepares a seccomp filter for use.
426  * @fprog: BPF program to install
427  *
428  * Returns filter on success or an ERR_PTR on failure.
429  */
430 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
431 {
432         struct seccomp_filter *sfilter;
433         int ret;
434         const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE);
435 
436         if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
437                 return ERR_PTR(-EINVAL);
438 
439         BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
440 
441         /*
442          * Installing a seccomp filter requires that the task has
443          * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
444          * This avoids scenarios where unprivileged tasks can affect the
445          * behavior of privileged children.
446          */
447         if (!task_no_new_privs(current) &&
448             security_capable(current_cred(), current_user_ns(),
449                                      CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) != 0)
450                 return ERR_PTR(-EACCES);
451 
452         /* Allocate a new seccomp_filter */
453         sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
454         if (!sfilter)
455                 return ERR_PTR(-ENOMEM);
456 
457         mutex_init(&sfilter->notify_lock);
458         ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
459                                         seccomp_check_filter, save_orig);
460         if (ret < 0) {
461                 kfree(sfilter);
462                 return ERR_PTR(ret);
463         }
464 
465         refcount_set(&sfilter->usage, 1);
466 
467         return sfilter;
468 }
469 
470 /**
471  * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
472  * @user_filter: pointer to the user data containing a sock_fprog.
473  *
474  * Returns 0 on success and non-zero otherwise.
475  */
476 static struct seccomp_filter *
477 seccomp_prepare_user_filter(const char __user *user_filter)
478 {
479         struct sock_fprog fprog;
480         struct seccomp_filter *filter = ERR_PTR(-EFAULT);
481 
482 #ifdef CONFIG_COMPAT
483         if (in_compat_syscall()) {
484                 struct compat_sock_fprog fprog32;
485                 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
486                         goto out;
487                 fprog.len = fprog32.len;
488                 fprog.filter = compat_ptr(fprog32.filter);
489         } else /* falls through to the if below. */
490 #endif
491         if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
492                 goto out;
493         filter = seccomp_prepare_filter(&fprog);
494 out:
495         return filter;
496 }
497 
498 /**
499  * seccomp_attach_filter: validate and attach filter
500  * @flags:  flags to change filter behavior
501  * @filter: seccomp filter to add to the current process
502  *
503  * Caller must be holding current->sighand->siglock lock.
504  *
505  * Returns 0 on success, -ve on error, or
506  *   - in TSYNC mode: the pid of a thread which was either not in the correct
507  *     seccomp mode or did not have an ancestral seccomp filter
508  *   - in NEW_LISTENER mode: the fd of the new listener
509  */
510 static long seccomp_attach_filter(unsigned int flags,
511                                   struct seccomp_filter *filter)
512 {
513         unsigned long total_insns;
514         struct seccomp_filter *walker;
515 
516         assert_spin_locked(&current->sighand->siglock);
517 
518         /* Validate resulting filter length. */
519         total_insns = filter->prog->len;
520         for (walker = current->seccomp.filter; walker; walker = walker->prev)
521                 total_insns += walker->prog->len + 4;  /* 4 instr penalty */
522         if (total_insns > MAX_INSNS_PER_PATH)
523                 return -ENOMEM;
524 
525         /* If thread sync has been requested, check that it is possible. */
526         if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
527                 int ret;
528 
529                 ret = seccomp_can_sync_threads();
530                 if (ret)
531                         return ret;
532         }
533 
534         /* Set log flag, if present. */
535         if (flags & SECCOMP_FILTER_FLAG_LOG)
536                 filter->log = true;
537 
538         /*
539          * If there is an existing filter, make it the prev and don't drop its
540          * task reference.
541          */
542         filter->prev = current->seccomp.filter;
543         current->seccomp.filter = filter;
544 
545         /* Now that the new filter is in place, synchronize to all threads. */
546         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
547                 seccomp_sync_threads(flags);
548 
549         return 0;
550 }
551 
552 static void __get_seccomp_filter(struct seccomp_filter *filter)
553 {
554         refcount_inc(&filter->usage);
555 }
556 
557 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
558 void get_seccomp_filter(struct task_struct *tsk)
559 {
560         struct seccomp_filter *orig = tsk->seccomp.filter;
561         if (!orig)
562                 return;
563         __get_seccomp_filter(orig);
564 }
565 
566 static inline void seccomp_filter_free(struct seccomp_filter *filter)
567 {
568         if (filter) {
569                 bpf_prog_destroy(filter->prog);
570                 kfree(filter);
571         }
572 }
573 
574 static void __put_seccomp_filter(struct seccomp_filter *orig)
575 {
576         /* Clean up single-reference branches iteratively. */
577         while (orig && refcount_dec_and_test(&orig->usage)) {
578                 struct seccomp_filter *freeme = orig;
579                 orig = orig->prev;
580                 seccomp_filter_free(freeme);
581         }
582 }
583 
584 /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
585 void put_seccomp_filter(struct task_struct *tsk)
586 {
587         __put_seccomp_filter(tsk->seccomp.filter);
588 }
589 
590 static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
591 {
592         clear_siginfo(info);
593         info->si_signo = SIGSYS;
594         info->si_code = SYS_SECCOMP;
595         info->si_call_addr = (void __user *)KSTK_EIP(current);
596         info->si_errno = reason;
597         info->si_arch = syscall_get_arch(current);
598         info->si_syscall = syscall;
599 }
600 
601 /**
602  * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
603  * @syscall: syscall number to send to userland
604  * @reason: filter-supplied reason code to send to userland (via si_errno)
605  *
606  * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
607  */
608 static void seccomp_send_sigsys(int syscall, int reason)
609 {
610         struct kernel_siginfo info;
611         seccomp_init_siginfo(&info, syscall, reason);
612         force_sig_info(&info);
613 }
614 #endif  /* CONFIG_SECCOMP_FILTER */
615 
616 /* For use with seccomp_actions_logged */
617 #define SECCOMP_LOG_KILL_PROCESS        (1 << 0)
618 #define SECCOMP_LOG_KILL_THREAD         (1 << 1)
619 #define SECCOMP_LOG_TRAP                (1 << 2)
620 #define SECCOMP_LOG_ERRNO               (1 << 3)
621 #define SECCOMP_LOG_TRACE               (1 << 4)
622 #define SECCOMP_LOG_LOG                 (1 << 5)
623 #define SECCOMP_LOG_ALLOW               (1 << 6)
624 #define SECCOMP_LOG_USER_NOTIF          (1 << 7)
625 
626 static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
627                                     SECCOMP_LOG_KILL_THREAD  |
628                                     SECCOMP_LOG_TRAP  |
629                                     SECCOMP_LOG_ERRNO |
630                                     SECCOMP_LOG_USER_NOTIF |
631                                     SECCOMP_LOG_TRACE |
632                                     SECCOMP_LOG_LOG;
633 
634 static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
635                                bool requested)
636 {
637         bool log = false;
638 
639         switch (action) {
640         case SECCOMP_RET_ALLOW:
641                 break;
642         case SECCOMP_RET_TRAP:
643                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
644                 break;
645         case SECCOMP_RET_ERRNO:
646                 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
647                 break;
648         case SECCOMP_RET_TRACE:
649                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
650                 break;
651         case SECCOMP_RET_USER_NOTIF:
652                 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
653                 break;
654         case SECCOMP_RET_LOG:
655                 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
656                 break;
657         case SECCOMP_RET_KILL_THREAD:
658                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
659                 break;
660         case SECCOMP_RET_KILL_PROCESS:
661         default:
662                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
663         }
664 
665         /*
666          * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
667          * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
668          * any action from being logged by removing the action name from the
669          * seccomp_actions_logged sysctl.
670          */
671         if (!log)
672                 return;
673 
674         audit_seccomp(syscall, signr, action);
675 }
676 
677 /*
678  * Secure computing mode 1 allows only read/write/exit/sigreturn.
679  * To be fully secure this must be combined with rlimit
680  * to limit the stack allocations too.
681  */
682 static const int mode1_syscalls[] = {
683         __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
684         0, /* null terminated */
685 };
686 
687 static void __secure_computing_strict(int this_syscall)
688 {
689         const int *syscall_whitelist = mode1_syscalls;
690 #ifdef CONFIG_COMPAT
691         if (in_compat_syscall())
692                 syscall_whitelist = get_compat_mode1_syscalls();
693 #endif
694         do {
695                 if (*syscall_whitelist == this_syscall)
696                         return;
697         } while (*++syscall_whitelist);
698 
699 #ifdef SECCOMP_DEBUG
700         dump_stack();
701 #endif
702         seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
703         do_exit(SIGKILL);
704 }
705 
706 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
707 void secure_computing_strict(int this_syscall)
708 {
709         int mode = current->seccomp.mode;
710 
711         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
712             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
713                 return;
714 
715         if (mode == SECCOMP_MODE_DISABLED)
716                 return;
717         else if (mode == SECCOMP_MODE_STRICT)
718                 __secure_computing_strict(this_syscall);
719         else
720                 BUG();
721 }
722 #else
723 
724 #ifdef CONFIG_SECCOMP_FILTER
725 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
726 {
727         /*
728          * Note: overflow is ok here, the id just needs to be unique per
729          * filter.
730          */
731         lockdep_assert_held(&filter->notify_lock);
732         return filter->notif->next_id++;
733 }
734 
735 static void seccomp_do_user_notification(int this_syscall,
736                                          struct seccomp_filter *match,
737                                          const struct seccomp_data *sd)
738 {
739         int err;
740         long ret = 0;
741         struct seccomp_knotif n = {};
742 
743         mutex_lock(&match->notify_lock);
744         err = -ENOSYS;
745         if (!match->notif)
746                 goto out;
747 
748         n.task = current;
749         n.state = SECCOMP_NOTIFY_INIT;
750         n.data = sd;
751         n.id = seccomp_next_notify_id(match);
752         init_completion(&n.ready);
753         list_add(&n.list, &match->notif->notifications);
754 
755         up(&match->notif->request);
756         wake_up_poll(&match->notif->wqh, EPOLLIN | EPOLLRDNORM);
757         mutex_unlock(&match->notify_lock);
758 
759         /*
760          * This is where we wait for a reply from userspace.
761          */
762         err = wait_for_completion_interruptible(&n.ready);
763         mutex_lock(&match->notify_lock);
764         if (err == 0) {
765                 ret = n.val;
766                 err = n.error;
767         }
768 
769         /*
770          * Note that it's possible the listener died in between the time when
771          * we were notified of a respons (or a signal) and when we were able to
772          * re-acquire the lock, so only delete from the list if the
773          * notification actually exists.
774          *
775          * Also note that this test is only valid because there's no way to
776          * *reattach* to a notifier right now. If one is added, we'll need to
777          * keep track of the notif itself and make sure they match here.
778          */
779         if (match->notif)
780                 list_del(&n.list);
781 out:
782         mutex_unlock(&match->notify_lock);
783         syscall_set_return_value(current, task_pt_regs(current),
784                                  err, ret);
785 }
786 
787 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
788                             const bool recheck_after_trace)
789 {
790         u32 filter_ret, action;
791         struct seccomp_filter *match = NULL;
792         int data;
793         struct seccomp_data sd_local;
794 
795         /*
796          * Make sure that any changes to mode from another thread have
797          * been seen after TIF_SECCOMP was seen.
798          */
799         rmb();
800 
801         if (!sd) {
802                 populate_seccomp_data(&sd_local);
803                 sd = &sd_local;
804         }
805 
806         filter_ret = seccomp_run_filters(sd, &match);
807         data = filter_ret & SECCOMP_RET_DATA;
808         action = filter_ret & SECCOMP_RET_ACTION_FULL;
809 
810         switch (action) {
811         case SECCOMP_RET_ERRNO:
812                 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
813                 if (data > MAX_ERRNO)
814                         data = MAX_ERRNO;
815                 syscall_set_return_value(current, task_pt_regs(current),
816                                          -data, 0);
817                 goto skip;
818 
819         case SECCOMP_RET_TRAP:
820                 /* Show the handler the original registers. */
821                 syscall_rollback(current, task_pt_regs(current));
822                 /* Let the filter pass back 16 bits of data. */
823                 seccomp_send_sigsys(this_syscall, data);
824                 goto skip;
825 
826         case SECCOMP_RET_TRACE:
827                 /* We've been put in this state by the ptracer already. */
828                 if (recheck_after_trace)
829                         return 0;
830 
831                 /* ENOSYS these calls if there is no tracer attached. */
832                 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
833                         syscall_set_return_value(current,
834                                                  task_pt_regs(current),
835                                                  -ENOSYS, 0);
836                         goto skip;
837                 }
838 
839                 /* Allow the BPF to provide the event message */
840                 ptrace_event(PTRACE_EVENT_SECCOMP, data);
841                 /*
842                  * The delivery of a fatal signal during event
843                  * notification may silently skip tracer notification,
844                  * which could leave us with a potentially unmodified
845                  * syscall that the tracer would have liked to have
846                  * changed. Since the process is about to die, we just
847                  * force the syscall to be skipped and let the signal
848                  * kill the process and correctly handle any tracer exit
849                  * notifications.
850                  */
851                 if (fatal_signal_pending(current))
852                         goto skip;
853                 /* Check if the tracer forced the syscall to be skipped. */
854                 this_syscall = syscall_get_nr(current, task_pt_regs(current));
855                 if (this_syscall < 0)
856                         goto skip;
857 
858                 /*
859                  * Recheck the syscall, since it may have changed. This
860                  * intentionally uses a NULL struct seccomp_data to force
861                  * a reload of all registers. This does not goto skip since
862                  * a skip would have already been reported.
863                  */
864                 if (__seccomp_filter(this_syscall, NULL, true))
865                         return -1;
866 
867                 return 0;
868 
869         case SECCOMP_RET_USER_NOTIF:
870                 seccomp_do_user_notification(this_syscall, match, sd);
871                 goto skip;
872 
873         case SECCOMP_RET_LOG:
874                 seccomp_log(this_syscall, 0, action, true);
875                 return 0;
876 
877         case SECCOMP_RET_ALLOW:
878                 /*
879                  * Note that the "match" filter will always be NULL for
880                  * this action since SECCOMP_RET_ALLOW is the starting
881                  * state in seccomp_run_filters().
882                  */
883                 return 0;
884 
885         case SECCOMP_RET_KILL_THREAD:
886         case SECCOMP_RET_KILL_PROCESS:
887         default:
888                 seccomp_log(this_syscall, SIGSYS, action, true);
889                 /* Dump core only if this is the last remaining thread. */
890                 if (action == SECCOMP_RET_KILL_PROCESS ||
891                     get_nr_threads(current) == 1) {
892                         kernel_siginfo_t info;
893 
894                         /* Show the original registers in the dump. */
895                         syscall_rollback(current, task_pt_regs(current));
896                         /* Trigger a manual coredump since do_exit skips it. */
897                         seccomp_init_siginfo(&info, this_syscall, data);
898                         do_coredump(&info);
899                 }
900                 if (action == SECCOMP_RET_KILL_PROCESS)
901                         do_group_exit(SIGSYS);
902                 else
903                         do_exit(SIGSYS);
904         }
905 
906         unreachable();
907 
908 skip:
909         seccomp_log(this_syscall, 0, action, match ? match->log : false);
910         return -1;
911 }
912 #else
913 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
914                             const bool recheck_after_trace)
915 {
916         BUG();
917 }
918 #endif
919 
920 int __secure_computing(const struct seccomp_data *sd)
921 {
922         int mode = current->seccomp.mode;
923         int this_syscall;
924 
925         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
926             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
927                 return 0;
928 
929         this_syscall = sd ? sd->nr :
930                 syscall_get_nr(current, task_pt_regs(current));
931 
932         switch (mode) {
933         case SECCOMP_MODE_STRICT:
934                 __secure_computing_strict(this_syscall);  /* may call do_exit */
935                 return 0;
936         case SECCOMP_MODE_FILTER:
937                 return __seccomp_filter(this_syscall, sd, false);
938         default:
939                 BUG();
940         }
941 }
942 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
943 
944 long prctl_get_seccomp(void)
945 {
946         return current->seccomp.mode;
947 }
948 
949 /**
950  * seccomp_set_mode_strict: internal function for setting strict seccomp
951  *
952  * Once current->seccomp.mode is non-zero, it may not be changed.
953  *
954  * Returns 0 on success or -EINVAL on failure.
955  */
956 static long seccomp_set_mode_strict(void)
957 {
958         const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
959         long ret = -EINVAL;
960 
961         spin_lock_irq(&current->sighand->siglock);
962 
963         if (!seccomp_may_assign_mode(seccomp_mode))
964                 goto out;
965 
966 #ifdef TIF_NOTSC
967         disable_TSC();
968 #endif
969         seccomp_assign_mode(current, seccomp_mode, 0);
970         ret = 0;
971 
972 out:
973         spin_unlock_irq(&current->sighand->siglock);
974 
975         return ret;
976 }
977 
978 #ifdef CONFIG_SECCOMP_FILTER
979 static int seccomp_notify_release(struct inode *inode, struct file *file)
980 {
981         struct seccomp_filter *filter = file->private_data;
982         struct seccomp_knotif *knotif;
983 
984         if (!filter)
985                 return 0;
986 
987         mutex_lock(&filter->notify_lock);
988 
989         /*
990          * If this file is being closed because e.g. the task who owned it
991          * died, let's wake everyone up who was waiting on us.
992          */
993         list_for_each_entry(knotif, &filter->notif->notifications, list) {
994                 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
995                         continue;
996 
997                 knotif->state = SECCOMP_NOTIFY_REPLIED;
998                 knotif->error = -ENOSYS;
999                 knotif->val = 0;
1000 
1001                 complete(&knotif->ready);
1002         }
1003 
1004         kfree(filter->notif);
1005         filter->notif = NULL;
1006         mutex_unlock(&filter->notify_lock);
1007         __put_seccomp_filter(filter);
1008         return 0;
1009 }
1010 
1011 static long seccomp_notify_recv(struct seccomp_filter *filter,
1012                                 void __user *buf)
1013 {
1014         struct seccomp_knotif *knotif = NULL, *cur;
1015         struct seccomp_notif unotif;
1016         ssize_t ret;
1017 
1018         memset(&unotif, 0, sizeof(unotif));
1019 
1020         ret = down_interruptible(&filter->notif->request);
1021         if (ret < 0)
1022                 return ret;
1023 
1024         mutex_lock(&filter->notify_lock);
1025         list_for_each_entry(cur, &filter->notif->notifications, list) {
1026                 if (cur->state == SECCOMP_NOTIFY_INIT) {
1027                         knotif = cur;
1028                         break;
1029                 }
1030         }
1031 
1032         /*
1033          * If we didn't find a notification, it could be that the task was
1034          * interrupted by a fatal signal between the time we were woken and
1035          * when we were able to acquire the rw lock.
1036          */
1037         if (!knotif) {
1038                 ret = -ENOENT;
1039                 goto out;
1040         }
1041 
1042         unotif.id = knotif->id;
1043         unotif.pid = task_pid_vnr(knotif->task);
1044         unotif.data = *(knotif->data);
1045 
1046         knotif->state = SECCOMP_NOTIFY_SENT;
1047         wake_up_poll(&filter->notif->wqh, EPOLLOUT | EPOLLWRNORM);
1048         ret = 0;
1049 out:
1050         mutex_unlock(&filter->notify_lock);
1051 
1052         if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1053                 ret = -EFAULT;
1054 
1055                 /*
1056                  * Userspace screwed up. To make sure that we keep this
1057                  * notification alive, let's reset it back to INIT. It
1058                  * may have died when we released the lock, so we need to make
1059                  * sure it's still around.
1060                  */
1061                 knotif = NULL;
1062                 mutex_lock(&filter->notify_lock);
1063                 list_for_each_entry(cur, &filter->notif->notifications, list) {
1064                         if (cur->id == unotif.id) {
1065                                 knotif = cur;
1066                                 break;
1067                         }
1068                 }
1069 
1070                 if (knotif) {
1071                         knotif->state = SECCOMP_NOTIFY_INIT;
1072                         up(&filter->notif->request);
1073                 }
1074                 mutex_unlock(&filter->notify_lock);
1075         }
1076 
1077         return ret;
1078 }
1079 
1080 static long seccomp_notify_send(struct seccomp_filter *filter,
1081                                 void __user *buf)
1082 {
1083         struct seccomp_notif_resp resp = {};
1084         struct seccomp_knotif *knotif = NULL, *cur;
1085         long ret;
1086 
1087         if (copy_from_user(&resp, buf, sizeof(resp)))
1088                 return -EFAULT;
1089 
1090         if (resp.flags)
1091                 return -EINVAL;
1092 
1093         ret = mutex_lock_interruptible(&filter->notify_lock);
1094         if (ret < 0)
1095                 return ret;
1096 
1097         list_for_each_entry(cur, &filter->notif->notifications, list) {
1098                 if (cur->id == resp.id) {
1099                         knotif = cur;
1100                         break;
1101                 }
1102         }
1103 
1104         if (!knotif) {
1105                 ret = -ENOENT;
1106                 goto out;
1107         }
1108 
1109         /* Allow exactly one reply. */
1110         if (knotif->state != SECCOMP_NOTIFY_SENT) {
1111                 ret = -EINPROGRESS;
1112                 goto out;
1113         }
1114 
1115         ret = 0;
1116         knotif->state = SECCOMP_NOTIFY_REPLIED;
1117         knotif->error = resp.error;
1118         knotif->val = resp.val;
1119         complete(&knotif->ready);
1120 out:
1121         mutex_unlock(&filter->notify_lock);
1122         return ret;
1123 }
1124 
1125 static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1126                                     void __user *buf)
1127 {
1128         struct seccomp_knotif *knotif = NULL;
1129         u64 id;
1130         long ret;
1131 
1132         if (copy_from_user(&id, buf, sizeof(id)))
1133                 return -EFAULT;
1134 
1135         ret = mutex_lock_interruptible(&filter->notify_lock);
1136         if (ret < 0)
1137                 return ret;
1138 
1139         ret = -ENOENT;
1140         list_for_each_entry(knotif, &filter->notif->notifications, list) {
1141                 if (knotif->id == id) {
1142                         if (knotif->state == SECCOMP_NOTIFY_SENT)
1143                                 ret = 0;
1144                         goto out;
1145                 }
1146         }
1147 
1148 out:
1149         mutex_unlock(&filter->notify_lock);
1150         return ret;
1151 }
1152 
1153 static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1154                                  unsigned long arg)
1155 {
1156         struct seccomp_filter *filter = file->private_data;
1157         void __user *buf = (void __user *)arg;
1158 
1159         switch (cmd) {
1160         case SECCOMP_IOCTL_NOTIF_RECV:
1161                 return seccomp_notify_recv(filter, buf);
1162         case SECCOMP_IOCTL_NOTIF_SEND:
1163                 return seccomp_notify_send(filter, buf);
1164         case SECCOMP_IOCTL_NOTIF_ID_VALID:
1165                 return seccomp_notify_id_valid(filter, buf);
1166         default:
1167                 return -EINVAL;
1168         }
1169 }
1170 
1171 static __poll_t seccomp_notify_poll(struct file *file,
1172                                     struct poll_table_struct *poll_tab)
1173 {
1174         struct seccomp_filter *filter = file->private_data;
1175         __poll_t ret = 0;
1176         struct seccomp_knotif *cur;
1177 
1178         poll_wait(file, &filter->notif->wqh, poll_tab);
1179 
1180         if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1181                 return EPOLLERR;
1182 
1183         list_for_each_entry(cur, &filter->notif->notifications, list) {
1184                 if (cur->state == SECCOMP_NOTIFY_INIT)
1185                         ret |= EPOLLIN | EPOLLRDNORM;
1186                 if (cur->state == SECCOMP_NOTIFY_SENT)
1187                         ret |= EPOLLOUT | EPOLLWRNORM;
1188                 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1189                         break;
1190         }
1191 
1192         mutex_unlock(&filter->notify_lock);
1193 
1194         return ret;
1195 }
1196 
1197 static const struct file_operations seccomp_notify_ops = {
1198         .poll = seccomp_notify_poll,
1199         .release = seccomp_notify_release,
1200         .unlocked_ioctl = seccomp_notify_ioctl,
1201 };
1202 
1203 static struct file *init_listener(struct seccomp_filter *filter)
1204 {
1205         struct file *ret = ERR_PTR(-EBUSY);
1206         struct seccomp_filter *cur;
1207 
1208         for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1209                 if (cur->notif)
1210                         goto out;
1211         }
1212 
1213         ret = ERR_PTR(-ENOMEM);
1214         filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1215         if (!filter->notif)
1216                 goto out;
1217 
1218         sema_init(&filter->notif->request, 0);
1219         filter->notif->next_id = get_random_u64();
1220         INIT_LIST_HEAD(&filter->notif->notifications);
1221         init_waitqueue_head(&filter->notif->wqh);
1222 
1223         ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1224                                  filter, O_RDWR);
1225         if (IS_ERR(ret))
1226                 goto out_notif;
1227 
1228         /* The file has a reference to it now */
1229         __get_seccomp_filter(filter);
1230 
1231 out_notif:
1232         if (IS_ERR(ret))
1233                 kfree(filter->notif);
1234 out:
1235         return ret;
1236 }
1237 
1238 /**
1239  * seccomp_set_mode_filter: internal function for setting seccomp filter
1240  * @flags:  flags to change filter behavior
1241  * @filter: struct sock_fprog containing filter
1242  *
1243  * This function may be called repeatedly to install additional filters.
1244  * Every filter successfully installed will be evaluated (in reverse order)
1245  * for each system call the task makes.
1246  *
1247  * Once current->seccomp.mode is non-zero, it may not be changed.
1248  *
1249  * Returns 0 on success or -EINVAL on failure.
1250  */
1251 static long seccomp_set_mode_filter(unsigned int flags,
1252                                     const char __user *filter)
1253 {
1254         const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1255         struct seccomp_filter *prepared = NULL;
1256         long ret = -EINVAL;
1257         int listener = -1;
1258         struct file *listener_f = NULL;
1259 
1260         /* Validate flags. */
1261         if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1262                 return -EINVAL;
1263 
1264         /*
1265          * In the successful case, NEW_LISTENER returns the new listener fd.
1266          * But in the failure case, TSYNC returns the thread that died. If you
1267          * combine these two flags, there's no way to tell whether something
1268          * succeeded or failed. So, let's disallow this combination.
1269          */
1270         if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1271             (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER))
1272                 return -EINVAL;
1273 
1274         /* Prepare the new filter before holding any locks. */
1275         prepared = seccomp_prepare_user_filter(filter);
1276         if (IS_ERR(prepared))
1277                 return PTR_ERR(prepared);
1278 
1279         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1280                 listener = get_unused_fd_flags(O_CLOEXEC);
1281                 if (listener < 0) {
1282                         ret = listener;
1283                         goto out_free;
1284                 }
1285 
1286                 listener_f = init_listener(prepared);
1287                 if (IS_ERR(listener_f)) {
1288                         put_unused_fd(listener);
1289                         ret = PTR_ERR(listener_f);
1290                         goto out_free;
1291                 }
1292         }
1293 
1294         /*
1295          * Make sure we cannot change seccomp or nnp state via TSYNC
1296          * while another thread is in the middle of calling exec.
1297          */
1298         if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1299             mutex_lock_killable(&current->signal->cred_guard_mutex))
1300                 goto out_put_fd;
1301 
1302         spin_lock_irq(&current->sighand->siglock);
1303 
1304         if (!seccomp_may_assign_mode(seccomp_mode))
1305                 goto out;
1306 
1307         ret = seccomp_attach_filter(flags, prepared);
1308         if (ret)
1309                 goto out;
1310         /* Do not free the successfully attached filter. */
1311         prepared = NULL;
1312 
1313         seccomp_assign_mode(current, seccomp_mode, flags);
1314 out:
1315         spin_unlock_irq(&current->sighand->siglock);
1316         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1317                 mutex_unlock(&current->signal->cred_guard_mutex);
1318 out_put_fd:
1319         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1320                 if (ret) {
1321                         listener_f->private_data = NULL;
1322                         fput(listener_f);
1323                         put_unused_fd(listener);
1324                 } else {
1325                         fd_install(listener, listener_f);
1326                         ret = listener;
1327                 }
1328         }
1329 out_free:
1330         seccomp_filter_free(prepared);
1331         return ret;
1332 }
1333 #else
1334 static inline long seccomp_set_mode_filter(unsigned int flags,
1335                                            const char __user *filter)
1336 {
1337         return -EINVAL;
1338 }
1339 #endif
1340 
1341 static long seccomp_get_action_avail(const char __user *uaction)
1342 {
1343         u32 action;
1344 
1345         if (copy_from_user(&action, uaction, sizeof(action)))
1346                 return -EFAULT;
1347 
1348         switch (action) {
1349         case SECCOMP_RET_KILL_PROCESS:
1350         case SECCOMP_RET_KILL_THREAD:
1351         case SECCOMP_RET_TRAP:
1352         case SECCOMP_RET_ERRNO:
1353         case SECCOMP_RET_USER_NOTIF:
1354         case SECCOMP_RET_TRACE:
1355         case SECCOMP_RET_LOG:
1356         case SECCOMP_RET_ALLOW:
1357                 break;
1358         default:
1359                 return -EOPNOTSUPP;
1360         }
1361 
1362         return 0;
1363 }
1364 
1365 static long seccomp_get_notif_sizes(void __user *usizes)
1366 {
1367         struct seccomp_notif_sizes sizes = {
1368                 .seccomp_notif = sizeof(struct seccomp_notif),
1369                 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1370                 .seccomp_data = sizeof(struct seccomp_data),
1371         };
1372 
1373         if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1374                 return -EFAULT;
1375 
1376         return 0;
1377 }
1378 
1379 /* Common entry point for both prctl and syscall. */
1380 static long do_seccomp(unsigned int op, unsigned int flags,
1381                        void __user *uargs)
1382 {
1383         switch (op) {
1384         case SECCOMP_SET_MODE_STRICT:
1385                 if (flags != 0 || uargs != NULL)
1386                         return -EINVAL;
1387                 return seccomp_set_mode_strict();
1388         case SECCOMP_SET_MODE_FILTER:
1389                 return seccomp_set_mode_filter(flags, uargs);
1390         case SECCOMP_GET_ACTION_AVAIL:
1391                 if (flags != 0)
1392                         return -EINVAL;
1393 
1394                 return seccomp_get_action_avail(uargs);
1395         case SECCOMP_GET_NOTIF_SIZES:
1396                 if (flags != 0)
1397                         return -EINVAL;
1398 
1399                 return seccomp_get_notif_sizes(uargs);
1400         default:
1401                 return -EINVAL;
1402         }
1403 }
1404 
1405 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1406                          void __user *, uargs)
1407 {
1408         return do_seccomp(op, flags, uargs);
1409 }
1410 
1411 /**
1412  * prctl_set_seccomp: configures current->seccomp.mode
1413  * @seccomp_mode: requested mode to use
1414  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1415  *
1416  * Returns 0 on success or -EINVAL on failure.
1417  */
1418 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
1419 {
1420         unsigned int op;
1421         void __user *uargs;
1422 
1423         switch (seccomp_mode) {
1424         case SECCOMP_MODE_STRICT:
1425                 op = SECCOMP_SET_MODE_STRICT;
1426                 /*
1427                  * Setting strict mode through prctl always ignored filter,
1428                  * so make sure it is always NULL here to pass the internal
1429                  * check in do_seccomp().
1430                  */
1431                 uargs = NULL;
1432                 break;
1433         case SECCOMP_MODE_FILTER:
1434                 op = SECCOMP_SET_MODE_FILTER;
1435                 uargs = filter;
1436                 break;
1437         default:
1438                 return -EINVAL;
1439         }
1440 
1441         /* prctl interface doesn't have flags, so they are always zero. */
1442         return do_seccomp(op, 0, uargs);
1443 }
1444 
1445 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1446 static struct seccomp_filter *get_nth_filter(struct task_struct *task,
1447                                              unsigned long filter_off)
1448 {
1449         struct seccomp_filter *orig, *filter;
1450         unsigned long count;
1451 
1452         /*
1453          * Note: this is only correct because the caller should be the (ptrace)
1454          * tracer of the task, otherwise lock_task_sighand is needed.
1455          */
1456         spin_lock_irq(&task->sighand->siglock);
1457 
1458         if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
1459                 spin_unlock_irq(&task->sighand->siglock);
1460                 return ERR_PTR(-EINVAL);
1461         }
1462 
1463         orig = task->seccomp.filter;
1464         __get_seccomp_filter(orig);
1465         spin_unlock_irq(&task->sighand->siglock);
1466 
1467         count = 0;
1468         for (filter = orig; filter; filter = filter->prev)
1469                 count++;
1470 
1471         if (filter_off >= count) {
1472                 filter = ERR_PTR(-ENOENT);
1473                 goto out;
1474         }
1475 
1476         count -= filter_off;
1477         for (filter = orig; filter && count > 1; filter = filter->prev)
1478                 count--;
1479 
1480         if (WARN_ON(count != 1 || !filter)) {
1481                 filter = ERR_PTR(-ENOENT);
1482                 goto out;
1483         }
1484 
1485         __get_seccomp_filter(filter);
1486 
1487 out:
1488         __put_seccomp_filter(orig);
1489         return filter;
1490 }
1491 
1492 long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
1493                         void __user *data)
1494 {
1495         struct seccomp_filter *filter;
1496         struct sock_fprog_kern *fprog;
1497         long ret;
1498 
1499         if (!capable(CAP_SYS_ADMIN) ||
1500             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1501                 return -EACCES;
1502         }
1503 
1504         filter = get_nth_filter(task, filter_off);
1505         if (IS_ERR(filter))
1506                 return PTR_ERR(filter);
1507 
1508         fprog = filter->prog->orig_prog;
1509         if (!fprog) {
1510                 /* This must be a new non-cBPF filter, since we save
1511                  * every cBPF filter's orig_prog above when
1512                  * CONFIG_CHECKPOINT_RESTORE is enabled.
1513                  */
1514                 ret = -EMEDIUMTYPE;
1515                 goto out;
1516         }
1517 
1518         ret = fprog->len;
1519         if (!data)
1520                 goto out;
1521 
1522         if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
1523                 ret = -EFAULT;
1524 
1525 out:
1526         __put_seccomp_filter(filter);
1527         return ret;
1528 }
1529 
1530 long seccomp_get_metadata(struct task_struct *task,
1531                           unsigned long size, void __user *data)
1532 {
1533         long ret;
1534         struct seccomp_filter *filter;
1535         struct seccomp_metadata kmd = {};
1536 
1537         if (!capable(CAP_SYS_ADMIN) ||
1538             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1539                 return -EACCES;
1540         }
1541 
1542         size = min_t(unsigned long, size, sizeof(kmd));
1543 
1544         if (size < sizeof(kmd.filter_off))
1545                 return -EINVAL;
1546 
1547         if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
1548                 return -EFAULT;
1549 
1550         filter = get_nth_filter(task, kmd.filter_off);
1551         if (IS_ERR(filter))
1552                 return PTR_ERR(filter);
1553 
1554         if (filter->log)
1555                 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
1556 
1557         ret = size;
1558         if (copy_to_user(data, &kmd, size))
1559                 ret = -EFAULT;
1560 
1561         __put_seccomp_filter(filter);
1562         return ret;
1563 }
1564 #endif
1565 
1566 #ifdef CONFIG_SYSCTL
1567 
1568 /* Human readable action names for friendly sysctl interaction */
1569 #define SECCOMP_RET_KILL_PROCESS_NAME   "kill_process"
1570 #define SECCOMP_RET_KILL_THREAD_NAME    "kill_thread"
1571 #define SECCOMP_RET_TRAP_NAME           "trap"
1572 #define SECCOMP_RET_ERRNO_NAME          "errno"
1573 #define SECCOMP_RET_USER_NOTIF_NAME     "user_notif"
1574 #define SECCOMP_RET_TRACE_NAME          "trace"
1575 #define SECCOMP_RET_LOG_NAME            "log"
1576 #define SECCOMP_RET_ALLOW_NAME          "allow"
1577 
1578 static const char seccomp_actions_avail[] =
1579                                 SECCOMP_RET_KILL_PROCESS_NAME   " "
1580                                 SECCOMP_RET_KILL_THREAD_NAME    " "
1581                                 SECCOMP_RET_TRAP_NAME           " "
1582                                 SECCOMP_RET_ERRNO_NAME          " "
1583                                 SECCOMP_RET_USER_NOTIF_NAME     " "
1584                                 SECCOMP_RET_TRACE_NAME          " "
1585                                 SECCOMP_RET_LOG_NAME            " "
1586                                 SECCOMP_RET_ALLOW_NAME;
1587 
1588 struct seccomp_log_name {
1589         u32             log;
1590         const char      *name;
1591 };
1592 
1593 static const struct seccomp_log_name seccomp_log_names[] = {
1594         { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
1595         { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
1596         { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
1597         { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
1598         { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
1599         { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
1600         { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
1601         { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
1602         { }
1603 };
1604 
1605 static bool seccomp_names_from_actions_logged(char *names, size_t size,
1606                                               u32 actions_logged,
1607                                               const char *sep)
1608 {
1609         const struct seccomp_log_name *cur;
1610         bool append_sep = false;
1611 
1612         for (cur = seccomp_log_names; cur->name && size; cur++) {
1613                 ssize_t ret;
1614 
1615                 if (!(actions_logged & cur->log))
1616                         continue;
1617 
1618                 if (append_sep) {
1619                         ret = strscpy(names, sep, size);
1620                         if (ret < 0)
1621                                 return false;
1622 
1623                         names += ret;
1624                         size -= ret;
1625                 } else
1626                         append_sep = true;
1627 
1628                 ret = strscpy(names, cur->name, size);
1629                 if (ret < 0)
1630                         return false;
1631 
1632                 names += ret;
1633                 size -= ret;
1634         }
1635 
1636         return true;
1637 }
1638 
1639 static bool seccomp_action_logged_from_name(u32 *action_logged,
1640                                             const char *name)
1641 {
1642         const struct seccomp_log_name *cur;
1643 
1644         for (cur = seccomp_log_names; cur->name; cur++) {
1645                 if (!strcmp(cur->name, name)) {
1646                         *action_logged = cur->log;
1647                         return true;
1648                 }
1649         }
1650 
1651         return false;
1652 }
1653 
1654 static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
1655 {
1656         char *name;
1657 
1658         *actions_logged = 0;
1659         while ((name = strsep(&names, " ")) && *name) {
1660                 u32 action_logged = 0;
1661 
1662                 if (!seccomp_action_logged_from_name(&action_logged, name))
1663                         return false;
1664 
1665                 *actions_logged |= action_logged;
1666         }
1667 
1668         return true;
1669 }
1670 
1671 static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1672                                size_t *lenp, loff_t *ppos)
1673 {
1674         char names[sizeof(seccomp_actions_avail)];
1675         struct ctl_table table;
1676 
1677         memset(names, 0, sizeof(names));
1678 
1679         if (!seccomp_names_from_actions_logged(names, sizeof(names),
1680                                                seccomp_actions_logged, " "))
1681                 return -EINVAL;
1682 
1683         table = *ro_table;
1684         table.data = names;
1685         table.maxlen = sizeof(names);
1686         return proc_dostring(&table, 0, buffer, lenp, ppos);
1687 }
1688 
1689 static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1690                                 size_t *lenp, loff_t *ppos, u32 *actions_logged)
1691 {
1692         char names[sizeof(seccomp_actions_avail)];
1693         struct ctl_table table;
1694         int ret;
1695 
1696         if (!capable(CAP_SYS_ADMIN))
1697                 return -EPERM;
1698 
1699         memset(names, 0, sizeof(names));
1700 
1701         table = *ro_table;
1702         table.data = names;
1703         table.maxlen = sizeof(names);
1704         ret = proc_dostring(&table, 1, buffer, lenp, ppos);
1705         if (ret)
1706                 return ret;
1707 
1708         if (!seccomp_actions_logged_from_names(actions_logged, table.data))
1709                 return -EINVAL;
1710 
1711         if (*actions_logged & SECCOMP_LOG_ALLOW)
1712                 return -EINVAL;
1713 
1714         seccomp_actions_logged = *actions_logged;
1715         return 0;
1716 }
1717 
1718 static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
1719                                  int ret)
1720 {
1721         char names[sizeof(seccomp_actions_avail)];
1722         char old_names[sizeof(seccomp_actions_avail)];
1723         const char *new = names;
1724         const char *old = old_names;
1725 
1726         if (!audit_enabled)
1727                 return;
1728 
1729         memset(names, 0, sizeof(names));
1730         memset(old_names, 0, sizeof(old_names));
1731 
1732         if (ret)
1733                 new = "?";
1734         else if (!actions_logged)
1735                 new = "(none)";
1736         else if (!seccomp_names_from_actions_logged(names, sizeof(names),
1737                                                     actions_logged, ","))
1738                 new = "?";
1739 
1740         if (!old_actions_logged)
1741                 old = "(none)";
1742         else if (!seccomp_names_from_actions_logged(old_names,
1743                                                     sizeof(old_names),
1744                                                     old_actions_logged, ","))
1745                 old = "?";
1746 
1747         return audit_seccomp_actions_logged(new, old, !ret);
1748 }
1749 
1750 static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
1751                                           void __user *buffer, size_t *lenp,
1752                                           loff_t *ppos)
1753 {
1754         int ret;
1755 
1756         if (write) {
1757                 u32 actions_logged = 0;
1758                 u32 old_actions_logged = seccomp_actions_logged;
1759 
1760                 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
1761                                            &actions_logged);
1762                 audit_actions_logged(actions_logged, old_actions_logged, ret);
1763         } else
1764                 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
1765 
1766         return ret;
1767 }
1768 
1769 static struct ctl_path seccomp_sysctl_path[] = {
1770         { .procname = "kernel", },
1771         { .procname = "seccomp", },
1772         { }
1773 };
1774 
1775 static struct ctl_table seccomp_sysctl_table[] = {
1776         {
1777                 .procname       = "actions_avail",
1778                 .data           = (void *) &seccomp_actions_avail,
1779                 .maxlen         = sizeof(seccomp_actions_avail),
1780                 .mode           = 0444,
1781                 .proc_handler   = proc_dostring,
1782         },
1783         {
1784                 .procname       = "actions_logged",
1785                 .mode           = 0644,
1786                 .proc_handler   = seccomp_actions_logged_handler,
1787         },
1788         { }
1789 };
1790 
1791 static int __init seccomp_sysctl_init(void)
1792 {
1793         struct ctl_table_header *hdr;
1794 
1795         hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
1796         if (!hdr)
1797                 pr_warn("seccomp: sysctl registration failed\n");
1798         else
1799                 kmemleak_not_leak(hdr);
1800 
1801         return 0;
1802 }
1803 
1804 device_initcall(seccomp_sysctl_init)
1805 
1806 #endif /* CONFIG_SYSCTL */
1807 

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