accel/amdxdna: use modern PM helpers
[drm/drm-misc.git] / kernel / seccomp.c
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1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/kernel/seccomp.c
5 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
7 * Copyright (C) 2012 Google, Inc.
8 * Will Drewry <wad@chromium.org>
10 * This defines a simple but solid secure-computing facility.
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.
16 #define pr_fmt(fmt) "seccomp: " fmt
18 #include <linux/refcount.h>
19 #include <linux/audit.h>
20 #include <linux/compat.h>
21 #include <linux/coredump.h>
22 #include <linux/kmemleak.h>
23 #include <linux/nospec.h>
24 #include <linux/prctl.h>
25 #include <linux/sched.h>
26 #include <linux/sched/task_stack.h>
27 #include <linux/seccomp.h>
28 #include <linux/slab.h>
29 #include <linux/syscalls.h>
30 #include <linux/sysctl.h>
32 /* Not exposed in headers: strictly internal use only. */
33 #define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1)
35 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
36 #include <asm/syscall.h>
37 #endif
39 #ifdef CONFIG_SECCOMP_FILTER
40 #include <linux/file.h>
41 #include <linux/filter.h>
42 #include <linux/pid.h>
43 #include <linux/ptrace.h>
44 #include <linux/capability.h>
45 #include <linux/uaccess.h>
46 #include <linux/anon_inodes.h>
47 #include <linux/lockdep.h>
50 * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
51 * wrong direction flag in the ioctl number. This is the broken one,
52 * which the kernel needs to keep supporting until all userspaces stop
53 * using the wrong command number.
55 #define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
57 enum notify_state {
58 SECCOMP_NOTIFY_INIT,
59 SECCOMP_NOTIFY_SENT,
60 SECCOMP_NOTIFY_REPLIED,
63 struct seccomp_knotif {
64 /* The struct pid of the task whose filter triggered the notification */
65 struct task_struct *task;
67 /* The "cookie" for this request; this is unique for this filter. */
68 u64 id;
71 * The seccomp data. This pointer is valid the entire time this
72 * notification is active, since it comes from __seccomp_filter which
73 * eclipses the entire lifecycle here.
75 const struct seccomp_data *data;
78 * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
79 * struct seccomp_knotif is created and starts out in INIT. Once the
80 * handler reads the notification off of an FD, it transitions to SENT.
81 * If a signal is received the state transitions back to INIT and
82 * another message is sent. When the userspace handler replies, state
83 * transitions to REPLIED.
85 enum notify_state state;
87 /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
88 int error;
89 long val;
90 u32 flags;
93 * Signals when this has changed states, such as the listener
94 * dying, a new seccomp addfd message, or changing to REPLIED
96 struct completion ready;
98 struct list_head list;
100 /* outstanding addfd requests */
101 struct list_head addfd;
105 * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
107 * @file: A reference to the file to install in the other task
108 * @fd: The fd number to install it at. If the fd number is -1, it means the
109 * installing process should allocate the fd as normal.
110 * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
111 * is allowed.
112 * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
113 * @setfd: whether or not SECCOMP_ADDFD_FLAG_SETFD was set during notify_addfd
114 * @ret: The return value of the installing process. It is set to the fd num
115 * upon success (>= 0).
116 * @completion: Indicates that the installing process has completed fd
117 * installation, or gone away (either due to successful
118 * reply, or signal)
119 * @list: list_head for chaining seccomp_kaddfd together.
122 struct seccomp_kaddfd {
123 struct file *file;
124 int fd;
125 unsigned int flags;
126 __u32 ioctl_flags;
128 union {
129 bool setfd;
130 /* To only be set on reply */
131 int ret;
133 struct completion completion;
134 struct list_head list;
138 * struct notification - container for seccomp userspace notifications. Since
139 * most seccomp filters will not have notification listeners attached and this
140 * structure is fairly large, we store the notification-specific stuff in a
141 * separate structure.
143 * @requests: A semaphore that users of this notification can wait on for
144 * changes. Actual reads and writes are still controlled with
145 * filter->notify_lock.
146 * @flags: A set of SECCOMP_USER_NOTIF_FD_* flags.
147 * @next_id: The id of the next request.
148 * @notifications: A list of struct seccomp_knotif elements.
151 struct notification {
152 atomic_t requests;
153 u32 flags;
154 u64 next_id;
155 struct list_head notifications;
158 #ifdef SECCOMP_ARCH_NATIVE
160 * struct action_cache - per-filter cache of seccomp actions per
161 * arch/syscall pair
163 * @allow_native: A bitmap where each bit represents whether the
164 * filter will always allow the syscall, for the
165 * native architecture.
166 * @allow_compat: A bitmap where each bit represents whether the
167 * filter will always allow the syscall, for the
168 * compat architecture.
170 struct action_cache {
171 DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
172 #ifdef SECCOMP_ARCH_COMPAT
173 DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
174 #endif
176 #else
177 struct action_cache { };
179 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
180 const struct seccomp_data *sd)
182 return false;
185 static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
188 #endif /* SECCOMP_ARCH_NATIVE */
191 * struct seccomp_filter - container for seccomp BPF programs
193 * @refs: Reference count to manage the object lifetime.
194 * A filter's reference count is incremented for each directly
195 * attached task, once for the dependent filter, and if
196 * requested for the user notifier. When @refs reaches zero,
197 * the filter can be freed.
198 * @users: A filter's @users count is incremented for each directly
199 * attached task (filter installation, fork(), thread_sync),
200 * and once for the dependent filter (tracked in filter->prev).
201 * When it reaches zero it indicates that no direct or indirect
202 * users of that filter exist. No new tasks can get associated with
203 * this filter after reaching 0. The @users count is always smaller
204 * or equal to @refs. Hence, reaching 0 for @users does not mean
205 * the filter can be freed.
206 * @cache: cache of arch/syscall mappings to actions
207 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
208 * @wait_killable_recv: Put notifying process in killable state once the
209 * notification is received by the userspace listener.
210 * @prev: points to a previously installed, or inherited, filter
211 * @prog: the BPF program to evaluate
212 * @notif: the struct that holds all notification related information
213 * @notify_lock: A lock for all notification-related accesses.
214 * @wqh: A wait queue for poll if a notifier is in use.
216 * seccomp_filter objects are organized in a tree linked via the @prev
217 * pointer. For any task, it appears to be a singly-linked list starting
218 * with current->seccomp.filter, the most recently attached or inherited filter.
219 * However, multiple filters may share a @prev node, by way of fork(), which
220 * results in a unidirectional tree existing in memory. This is similar to
221 * how namespaces work.
223 * seccomp_filter objects should never be modified after being attached
224 * to a task_struct (other than @refs).
226 struct seccomp_filter {
227 refcount_t refs;
228 refcount_t users;
229 bool log;
230 bool wait_killable_recv;
231 struct action_cache cache;
232 struct seccomp_filter *prev;
233 struct bpf_prog *prog;
234 struct notification *notif;
235 struct mutex notify_lock;
236 wait_queue_head_t wqh;
239 /* Limit any path through the tree to 256KB worth of instructions. */
240 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
243 * Endianness is explicitly ignored and left for BPF program authors to manage
244 * as per the specific architecture.
246 static void populate_seccomp_data(struct seccomp_data *sd)
249 * Instead of using current_pt_reg(), we're already doing the work
250 * to safely fetch "current", so just use "task" everywhere below.
252 struct task_struct *task = current;
253 struct pt_regs *regs = task_pt_regs(task);
254 unsigned long args[6];
256 sd->nr = syscall_get_nr(task, regs);
257 sd->arch = syscall_get_arch(task);
258 syscall_get_arguments(task, regs, args);
259 sd->args[0] = args[0];
260 sd->args[1] = args[1];
261 sd->args[2] = args[2];
262 sd->args[3] = args[3];
263 sd->args[4] = args[4];
264 sd->args[5] = args[5];
265 sd->instruction_pointer = KSTK_EIP(task);
269 * seccomp_check_filter - verify seccomp filter code
270 * @filter: filter to verify
271 * @flen: length of filter
273 * Takes a previously checked filter (by bpf_check_classic) and
274 * redirects all filter code that loads struct sk_buff data
275 * and related data through seccomp_bpf_load. It also
276 * enforces length and alignment checking of those loads.
278 * Returns 0 if the rule set is legal or -EINVAL if not.
280 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
282 int pc;
283 for (pc = 0; pc < flen; pc++) {
284 struct sock_filter *ftest = &filter[pc];
285 u16 code = ftest->code;
286 u32 k = ftest->k;
288 switch (code) {
289 case BPF_LD | BPF_W | BPF_ABS:
290 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
291 /* 32-bit aligned and not out of bounds. */
292 if (k >= sizeof(struct seccomp_data) || k & 3)
293 return -EINVAL;
294 continue;
295 case BPF_LD | BPF_W | BPF_LEN:
296 ftest->code = BPF_LD | BPF_IMM;
297 ftest->k = sizeof(struct seccomp_data);
298 continue;
299 case BPF_LDX | BPF_W | BPF_LEN:
300 ftest->code = BPF_LDX | BPF_IMM;
301 ftest->k = sizeof(struct seccomp_data);
302 continue;
303 /* Explicitly include allowed calls. */
304 case BPF_RET | BPF_K:
305 case BPF_RET | BPF_A:
306 case BPF_ALU | BPF_ADD | BPF_K:
307 case BPF_ALU | BPF_ADD | BPF_X:
308 case BPF_ALU | BPF_SUB | BPF_K:
309 case BPF_ALU | BPF_SUB | BPF_X:
310 case BPF_ALU | BPF_MUL | BPF_K:
311 case BPF_ALU | BPF_MUL | BPF_X:
312 case BPF_ALU | BPF_DIV | BPF_K:
313 case BPF_ALU | BPF_DIV | BPF_X:
314 case BPF_ALU | BPF_AND | BPF_K:
315 case BPF_ALU | BPF_AND | BPF_X:
316 case BPF_ALU | BPF_OR | BPF_K:
317 case BPF_ALU | BPF_OR | BPF_X:
318 case BPF_ALU | BPF_XOR | BPF_K:
319 case BPF_ALU | BPF_XOR | BPF_X:
320 case BPF_ALU | BPF_LSH | BPF_K:
321 case BPF_ALU | BPF_LSH | BPF_X:
322 case BPF_ALU | BPF_RSH | BPF_K:
323 case BPF_ALU | BPF_RSH | BPF_X:
324 case BPF_ALU | BPF_NEG:
325 case BPF_LD | BPF_IMM:
326 case BPF_LDX | BPF_IMM:
327 case BPF_MISC | BPF_TAX:
328 case BPF_MISC | BPF_TXA:
329 case BPF_LD | BPF_MEM:
330 case BPF_LDX | BPF_MEM:
331 case BPF_ST:
332 case BPF_STX:
333 case BPF_JMP | BPF_JA:
334 case BPF_JMP | BPF_JEQ | BPF_K:
335 case BPF_JMP | BPF_JEQ | BPF_X:
336 case BPF_JMP | BPF_JGE | BPF_K:
337 case BPF_JMP | BPF_JGE | BPF_X:
338 case BPF_JMP | BPF_JGT | BPF_K:
339 case BPF_JMP | BPF_JGT | BPF_X:
340 case BPF_JMP | BPF_JSET | BPF_K:
341 case BPF_JMP | BPF_JSET | BPF_X:
342 continue;
343 default:
344 return -EINVAL;
347 return 0;
350 #ifdef SECCOMP_ARCH_NATIVE
351 static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
352 size_t bitmap_size,
353 int syscall_nr)
355 if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
356 return false;
357 syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
359 return test_bit(syscall_nr, bitmap);
363 * seccomp_cache_check_allow - lookup seccomp cache
364 * @sfilter: The seccomp filter
365 * @sd: The seccomp data to lookup the cache with
367 * Returns true if the seccomp_data is cached and allowed.
369 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
370 const struct seccomp_data *sd)
372 int syscall_nr = sd->nr;
373 const struct action_cache *cache = &sfilter->cache;
375 #ifndef SECCOMP_ARCH_COMPAT
376 /* A native-only architecture doesn't need to check sd->arch. */
377 return seccomp_cache_check_allow_bitmap(cache->allow_native,
378 SECCOMP_ARCH_NATIVE_NR,
379 syscall_nr);
380 #else
381 if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
382 return seccomp_cache_check_allow_bitmap(cache->allow_native,
383 SECCOMP_ARCH_NATIVE_NR,
384 syscall_nr);
385 if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
386 return seccomp_cache_check_allow_bitmap(cache->allow_compat,
387 SECCOMP_ARCH_COMPAT_NR,
388 syscall_nr);
389 #endif /* SECCOMP_ARCH_COMPAT */
391 WARN_ON_ONCE(true);
392 return false;
394 #endif /* SECCOMP_ARCH_NATIVE */
396 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
398 * seccomp_run_filters - evaluates all seccomp filters against @sd
399 * @sd: optional seccomp data to be passed to filters
400 * @match: stores struct seccomp_filter that resulted in the return value,
401 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
402 * be unchanged.
404 * Returns valid seccomp BPF response codes.
406 static u32 seccomp_run_filters(const struct seccomp_data *sd,
407 struct seccomp_filter **match)
409 u32 ret = SECCOMP_RET_ALLOW;
410 /* Make sure cross-thread synced filter points somewhere sane. */
411 struct seccomp_filter *f =
412 READ_ONCE(current->seccomp.filter);
414 /* Ensure unexpected behavior doesn't result in failing open. */
415 if (WARN_ON(f == NULL))
416 return SECCOMP_RET_KILL_PROCESS;
418 if (seccomp_cache_check_allow(f, sd))
419 return SECCOMP_RET_ALLOW;
422 * All filters in the list are evaluated and the lowest BPF return
423 * value always takes priority (ignoring the DATA).
425 for (; f; f = f->prev) {
426 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
428 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
429 ret = cur_ret;
430 *match = f;
433 return ret;
435 #endif /* CONFIG_SECCOMP_FILTER */
437 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
439 assert_spin_locked(&current->sighand->siglock);
441 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
442 return false;
444 return true;
447 void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
449 static inline void seccomp_assign_mode(struct task_struct *task,
450 unsigned long seccomp_mode,
451 unsigned long flags)
453 assert_spin_locked(&task->sighand->siglock);
455 task->seccomp.mode = seccomp_mode;
457 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
458 * filter) is set.
460 smp_mb__before_atomic();
461 /* Assume default seccomp processes want spec flaw mitigation. */
462 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
463 arch_seccomp_spec_mitigate(task);
464 set_task_syscall_work(task, SECCOMP);
467 #ifdef CONFIG_SECCOMP_FILTER
468 /* Returns 1 if the parent is an ancestor of the child. */
469 static int is_ancestor(struct seccomp_filter *parent,
470 struct seccomp_filter *child)
472 /* NULL is the root ancestor. */
473 if (parent == NULL)
474 return 1;
475 for (; child; child = child->prev)
476 if (child == parent)
477 return 1;
478 return 0;
482 * seccomp_can_sync_threads: checks if all threads can be synchronized
484 * Expects sighand and cred_guard_mutex locks to be held.
486 * Returns 0 on success, -ve on error, or the pid of a thread which was
487 * either not in the correct seccomp mode or did not have an ancestral
488 * seccomp filter.
490 static inline pid_t seccomp_can_sync_threads(void)
492 struct task_struct *thread, *caller;
494 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
495 assert_spin_locked(&current->sighand->siglock);
497 /* Validate all threads being eligible for synchronization. */
498 caller = current;
499 for_each_thread(caller, thread) {
500 pid_t failed;
502 /* Skip current, since it is initiating the sync. */
503 if (thread == caller)
504 continue;
505 /* Skip exited threads. */
506 if (thread->flags & PF_EXITING)
507 continue;
509 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
510 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
511 is_ancestor(thread->seccomp.filter,
512 caller->seccomp.filter)))
513 continue;
515 /* Return the first thread that cannot be synchronized. */
516 failed = task_pid_vnr(thread);
517 /* If the pid cannot be resolved, then return -ESRCH */
518 if (WARN_ON(failed == 0))
519 failed = -ESRCH;
520 return failed;
523 return 0;
526 static inline void seccomp_filter_free(struct seccomp_filter *filter)
528 if (filter) {
529 bpf_prog_destroy(filter->prog);
530 kfree(filter);
534 static void __seccomp_filter_orphan(struct seccomp_filter *orig)
536 while (orig && refcount_dec_and_test(&orig->users)) {
537 if (waitqueue_active(&orig->wqh))
538 wake_up_poll(&orig->wqh, EPOLLHUP);
539 orig = orig->prev;
543 static void __put_seccomp_filter(struct seccomp_filter *orig)
545 /* Clean up single-reference branches iteratively. */
546 while (orig && refcount_dec_and_test(&orig->refs)) {
547 struct seccomp_filter *freeme = orig;
548 orig = orig->prev;
549 seccomp_filter_free(freeme);
553 static void __seccomp_filter_release(struct seccomp_filter *orig)
555 /* Notify about any unused filters in the task's former filter tree. */
556 __seccomp_filter_orphan(orig);
557 /* Finally drop all references to the task's former tree. */
558 __put_seccomp_filter(orig);
562 * seccomp_filter_release - Detach the task from its filter tree,
563 * drop its reference count, and notify
564 * about unused filters
566 * @tsk: task the filter should be released from.
568 * This function should only be called when the task is exiting as
569 * it detaches it from its filter tree. PF_EXITING has to be set
570 * for the task.
572 void seccomp_filter_release(struct task_struct *tsk)
574 struct seccomp_filter *orig;
576 if (WARN_ON((tsk->flags & PF_EXITING) == 0))
577 return;
579 spin_lock_irq(&tsk->sighand->siglock);
580 orig = tsk->seccomp.filter;
581 /* Detach task from its filter tree. */
582 tsk->seccomp.filter = NULL;
583 spin_unlock_irq(&tsk->sighand->siglock);
584 __seccomp_filter_release(orig);
588 * seccomp_sync_threads: sets all threads to use current's filter
590 * @flags: SECCOMP_FILTER_FLAG_* flags to set during sync.
592 * Expects sighand and cred_guard_mutex locks to be held, and for
593 * seccomp_can_sync_threads() to have returned success already
594 * without dropping the locks.
597 static inline void seccomp_sync_threads(unsigned long flags)
599 struct task_struct *thread, *caller;
601 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
602 assert_spin_locked(&current->sighand->siglock);
604 /* Synchronize all threads. */
605 caller = current;
606 for_each_thread(caller, thread) {
607 /* Skip current, since it needs no changes. */
608 if (thread == caller)
609 continue;
612 * Skip exited threads. seccomp_filter_release could have
613 * been already called for this task.
615 if (thread->flags & PF_EXITING)
616 continue;
618 /* Get a task reference for the new leaf node. */
619 get_seccomp_filter(caller);
622 * Drop the task reference to the shared ancestor since
623 * current's path will hold a reference. (This also
624 * allows a put before the assignment.)
626 __seccomp_filter_release(thread->seccomp.filter);
628 /* Make our new filter tree visible. */
629 smp_store_release(&thread->seccomp.filter,
630 caller->seccomp.filter);
631 atomic_set(&thread->seccomp.filter_count,
632 atomic_read(&caller->seccomp.filter_count));
635 * Don't let an unprivileged task work around
636 * the no_new_privs restriction by creating
637 * a thread that sets it up, enters seccomp,
638 * then dies.
640 if (task_no_new_privs(caller))
641 task_set_no_new_privs(thread);
644 * Opt the other thread into seccomp if needed.
645 * As threads are considered to be trust-realm
646 * equivalent (see ptrace_may_access), it is safe to
647 * allow one thread to transition the other.
649 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
650 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
651 flags);
656 * seccomp_prepare_filter: Prepares a seccomp filter for use.
657 * @fprog: BPF program to install
659 * Returns filter on success or an ERR_PTR on failure.
661 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
663 struct seccomp_filter *sfilter;
664 int ret;
665 const bool save_orig =
666 #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
667 true;
668 #else
669 false;
670 #endif
672 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
673 return ERR_PTR(-EINVAL);
675 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
678 * Installing a seccomp filter requires that the task has
679 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
680 * This avoids scenarios where unprivileged tasks can affect the
681 * behavior of privileged children.
683 if (!task_no_new_privs(current) &&
684 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
685 return ERR_PTR(-EACCES);
687 /* Allocate a new seccomp_filter */
688 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
689 if (!sfilter)
690 return ERR_PTR(-ENOMEM);
692 mutex_init(&sfilter->notify_lock);
693 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
694 seccomp_check_filter, save_orig);
695 if (ret < 0) {
696 kfree(sfilter);
697 return ERR_PTR(ret);
700 refcount_set(&sfilter->refs, 1);
701 refcount_set(&sfilter->users, 1);
702 init_waitqueue_head(&sfilter->wqh);
704 return sfilter;
708 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
709 * @user_filter: pointer to the user data containing a sock_fprog.
711 * Returns 0 on success and non-zero otherwise.
713 static struct seccomp_filter *
714 seccomp_prepare_user_filter(const char __user *user_filter)
716 struct sock_fprog fprog;
717 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
719 #ifdef CONFIG_COMPAT
720 if (in_compat_syscall()) {
721 struct compat_sock_fprog fprog32;
722 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
723 goto out;
724 fprog.len = fprog32.len;
725 fprog.filter = compat_ptr(fprog32.filter);
726 } else /* falls through to the if below. */
727 #endif
728 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
729 goto out;
730 filter = seccomp_prepare_filter(&fprog);
731 out:
732 return filter;
735 #ifdef SECCOMP_ARCH_NATIVE
737 * seccomp_is_const_allow - check if filter is constant allow with given data
738 * @fprog: The BPF programs
739 * @sd: The seccomp data to check against, only syscall number and arch
740 * number are considered constant.
742 static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
743 struct seccomp_data *sd)
745 unsigned int reg_value = 0;
746 unsigned int pc;
747 bool op_res;
749 if (WARN_ON_ONCE(!fprog))
750 return false;
752 for (pc = 0; pc < fprog->len; pc++) {
753 struct sock_filter *insn = &fprog->filter[pc];
754 u16 code = insn->code;
755 u32 k = insn->k;
757 switch (code) {
758 case BPF_LD | BPF_W | BPF_ABS:
759 switch (k) {
760 case offsetof(struct seccomp_data, nr):
761 reg_value = sd->nr;
762 break;
763 case offsetof(struct seccomp_data, arch):
764 reg_value = sd->arch;
765 break;
766 default:
767 /* can't optimize (non-constant value load) */
768 return false;
770 break;
771 case BPF_RET | BPF_K:
772 /* reached return with constant values only, check allow */
773 return k == SECCOMP_RET_ALLOW;
774 case BPF_JMP | BPF_JA:
775 pc += insn->k;
776 break;
777 case BPF_JMP | BPF_JEQ | BPF_K:
778 case BPF_JMP | BPF_JGE | BPF_K:
779 case BPF_JMP | BPF_JGT | BPF_K:
780 case BPF_JMP | BPF_JSET | BPF_K:
781 switch (BPF_OP(code)) {
782 case BPF_JEQ:
783 op_res = reg_value == k;
784 break;
785 case BPF_JGE:
786 op_res = reg_value >= k;
787 break;
788 case BPF_JGT:
789 op_res = reg_value > k;
790 break;
791 case BPF_JSET:
792 op_res = !!(reg_value & k);
793 break;
794 default:
795 /* can't optimize (unknown jump) */
796 return false;
799 pc += op_res ? insn->jt : insn->jf;
800 break;
801 case BPF_ALU | BPF_AND | BPF_K:
802 reg_value &= k;
803 break;
804 default:
805 /* can't optimize (unknown insn) */
806 return false;
810 /* ran off the end of the filter?! */
811 WARN_ON(1);
812 return false;
815 static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
816 void *bitmap, const void *bitmap_prev,
817 size_t bitmap_size, int arch)
819 struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
820 struct seccomp_data sd;
821 int nr;
823 if (bitmap_prev) {
824 /* The new filter must be as restrictive as the last. */
825 bitmap_copy(bitmap, bitmap_prev, bitmap_size);
826 } else {
827 /* Before any filters, all syscalls are always allowed. */
828 bitmap_fill(bitmap, bitmap_size);
831 for (nr = 0; nr < bitmap_size; nr++) {
832 /* No bitmap change: not a cacheable action. */
833 if (!test_bit(nr, bitmap))
834 continue;
836 sd.nr = nr;
837 sd.arch = arch;
839 /* No bitmap change: continue to always allow. */
840 if (seccomp_is_const_allow(fprog, &sd))
841 continue;
844 * Not a cacheable action: always run filters.
845 * atomic clear_bit() not needed, filter not visible yet.
847 __clear_bit(nr, bitmap);
852 * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
853 * @sfilter: The seccomp filter
855 * Returns 0 if successful or -errno if error occurred.
857 static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
859 struct action_cache *cache = &sfilter->cache;
860 const struct action_cache *cache_prev =
861 sfilter->prev ? &sfilter->prev->cache : NULL;
863 seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
864 cache_prev ? cache_prev->allow_native : NULL,
865 SECCOMP_ARCH_NATIVE_NR,
866 SECCOMP_ARCH_NATIVE);
868 #ifdef SECCOMP_ARCH_COMPAT
869 seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
870 cache_prev ? cache_prev->allow_compat : NULL,
871 SECCOMP_ARCH_COMPAT_NR,
872 SECCOMP_ARCH_COMPAT);
873 #endif /* SECCOMP_ARCH_COMPAT */
875 #endif /* SECCOMP_ARCH_NATIVE */
878 * seccomp_attach_filter: validate and attach filter
879 * @flags: flags to change filter behavior
880 * @filter: seccomp filter to add to the current process
882 * Caller must be holding current->sighand->siglock lock.
884 * Returns 0 on success, -ve on error, or
885 * - in TSYNC mode: the pid of a thread which was either not in the correct
886 * seccomp mode or did not have an ancestral seccomp filter
887 * - in NEW_LISTENER mode: the fd of the new listener
889 static long seccomp_attach_filter(unsigned int flags,
890 struct seccomp_filter *filter)
892 unsigned long total_insns;
893 struct seccomp_filter *walker;
895 assert_spin_locked(&current->sighand->siglock);
897 /* Validate resulting filter length. */
898 total_insns = filter->prog->len;
899 for (walker = current->seccomp.filter; walker; walker = walker->prev)
900 total_insns += walker->prog->len + 4; /* 4 instr penalty */
901 if (total_insns > MAX_INSNS_PER_PATH)
902 return -ENOMEM;
904 /* If thread sync has been requested, check that it is possible. */
905 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
906 int ret;
908 ret = seccomp_can_sync_threads();
909 if (ret) {
910 if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
911 return -ESRCH;
912 else
913 return ret;
917 /* Set log flag, if present. */
918 if (flags & SECCOMP_FILTER_FLAG_LOG)
919 filter->log = true;
921 /* Set wait killable flag, if present. */
922 if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
923 filter->wait_killable_recv = true;
926 * If there is an existing filter, make it the prev and don't drop its
927 * task reference.
929 filter->prev = current->seccomp.filter;
930 seccomp_cache_prepare(filter);
931 current->seccomp.filter = filter;
932 atomic_inc(&current->seccomp.filter_count);
934 /* Now that the new filter is in place, synchronize to all threads. */
935 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
936 seccomp_sync_threads(flags);
938 return 0;
941 static void __get_seccomp_filter(struct seccomp_filter *filter)
943 refcount_inc(&filter->refs);
946 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
947 void get_seccomp_filter(struct task_struct *tsk)
949 struct seccomp_filter *orig = tsk->seccomp.filter;
950 if (!orig)
951 return;
952 __get_seccomp_filter(orig);
953 refcount_inc(&orig->users);
956 #endif /* CONFIG_SECCOMP_FILTER */
958 /* For use with seccomp_actions_logged */
959 #define SECCOMP_LOG_KILL_PROCESS (1 << 0)
960 #define SECCOMP_LOG_KILL_THREAD (1 << 1)
961 #define SECCOMP_LOG_TRAP (1 << 2)
962 #define SECCOMP_LOG_ERRNO (1 << 3)
963 #define SECCOMP_LOG_TRACE (1 << 4)
964 #define SECCOMP_LOG_LOG (1 << 5)
965 #define SECCOMP_LOG_ALLOW (1 << 6)
966 #define SECCOMP_LOG_USER_NOTIF (1 << 7)
968 static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
969 SECCOMP_LOG_KILL_THREAD |
970 SECCOMP_LOG_TRAP |
971 SECCOMP_LOG_ERRNO |
972 SECCOMP_LOG_USER_NOTIF |
973 SECCOMP_LOG_TRACE |
974 SECCOMP_LOG_LOG;
976 static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
977 bool requested)
979 bool log = false;
981 switch (action) {
982 case SECCOMP_RET_ALLOW:
983 break;
984 case SECCOMP_RET_TRAP:
985 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
986 break;
987 case SECCOMP_RET_ERRNO:
988 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
989 break;
990 case SECCOMP_RET_TRACE:
991 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
992 break;
993 case SECCOMP_RET_USER_NOTIF:
994 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
995 break;
996 case SECCOMP_RET_LOG:
997 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
998 break;
999 case SECCOMP_RET_KILL_THREAD:
1000 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
1001 break;
1002 case SECCOMP_RET_KILL_PROCESS:
1003 default:
1004 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
1008 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
1009 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
1010 * any action from being logged by removing the action name from the
1011 * seccomp_actions_logged sysctl.
1013 if (!log)
1014 return;
1016 audit_seccomp(syscall, signr, action);
1020 * Secure computing mode 1 allows only read/write/exit/sigreturn.
1021 * To be fully secure this must be combined with rlimit
1022 * to limit the stack allocations too.
1024 static const int mode1_syscalls[] = {
1025 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
1026 -1, /* negative terminated */
1029 static void __secure_computing_strict(int this_syscall)
1031 const int *allowed_syscalls = mode1_syscalls;
1032 #ifdef CONFIG_COMPAT
1033 if (in_compat_syscall())
1034 allowed_syscalls = get_compat_mode1_syscalls();
1035 #endif
1036 do {
1037 if (*allowed_syscalls == this_syscall)
1038 return;
1039 } while (*++allowed_syscalls != -1);
1041 #ifdef SECCOMP_DEBUG
1042 dump_stack();
1043 #endif
1044 current->seccomp.mode = SECCOMP_MODE_DEAD;
1045 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1046 do_exit(SIGKILL);
1049 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1050 void secure_computing_strict(int this_syscall)
1052 int mode = current->seccomp.mode;
1054 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1055 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1056 return;
1058 if (mode == SECCOMP_MODE_DISABLED)
1059 return;
1060 else if (mode == SECCOMP_MODE_STRICT)
1061 __secure_computing_strict(this_syscall);
1062 else
1063 BUG();
1065 #else
1067 #ifdef CONFIG_SECCOMP_FILTER
1068 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1071 * Note: overflow is ok here, the id just needs to be unique per
1072 * filter.
1074 lockdep_assert_held(&filter->notify_lock);
1075 return filter->notif->next_id++;
1078 static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
1080 int fd;
1083 * Remove the notification, and reset the list pointers, indicating
1084 * that it has been handled.
1086 list_del_init(&addfd->list);
1087 if (!addfd->setfd)
1088 fd = receive_fd(addfd->file, NULL, addfd->flags);
1089 else
1090 fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
1091 addfd->ret = fd;
1093 if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
1094 /* If we fail reset and return an error to the notifier */
1095 if (fd < 0) {
1096 n->state = SECCOMP_NOTIFY_SENT;
1097 } else {
1098 /* Return the FD we just added */
1099 n->flags = 0;
1100 n->error = 0;
1101 n->val = fd;
1106 * Mark the notification as completed. From this point, addfd mem
1107 * might be invalidated and we can't safely read it anymore.
1109 complete(&addfd->completion);
1112 static bool should_sleep_killable(struct seccomp_filter *match,
1113 struct seccomp_knotif *n)
1115 return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
1118 static int seccomp_do_user_notification(int this_syscall,
1119 struct seccomp_filter *match,
1120 const struct seccomp_data *sd)
1122 int err;
1123 u32 flags = 0;
1124 long ret = 0;
1125 struct seccomp_knotif n = {};
1126 struct seccomp_kaddfd *addfd, *tmp;
1128 mutex_lock(&match->notify_lock);
1129 err = -ENOSYS;
1130 if (!match->notif)
1131 goto out;
1133 n.task = current;
1134 n.state = SECCOMP_NOTIFY_INIT;
1135 n.data = sd;
1136 n.id = seccomp_next_notify_id(match);
1137 init_completion(&n.ready);
1138 list_add_tail(&n.list, &match->notif->notifications);
1139 INIT_LIST_HEAD(&n.addfd);
1141 atomic_inc(&match->notif->requests);
1142 if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1143 wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN | EPOLLRDNORM);
1144 else
1145 wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
1148 * This is where we wait for a reply from userspace.
1150 do {
1151 bool wait_killable = should_sleep_killable(match, &n);
1153 mutex_unlock(&match->notify_lock);
1154 if (wait_killable)
1155 err = wait_for_completion_killable(&n.ready);
1156 else
1157 err = wait_for_completion_interruptible(&n.ready);
1158 mutex_lock(&match->notify_lock);
1160 if (err != 0) {
1162 * Check to see if the notifcation got picked up and
1163 * whether we should switch to wait killable.
1165 if (!wait_killable && should_sleep_killable(match, &n))
1166 continue;
1168 goto interrupted;
1171 addfd = list_first_entry_or_null(&n.addfd,
1172 struct seccomp_kaddfd, list);
1173 /* Check if we were woken up by a addfd message */
1174 if (addfd)
1175 seccomp_handle_addfd(addfd, &n);
1177 } while (n.state != SECCOMP_NOTIFY_REPLIED);
1179 ret = n.val;
1180 err = n.error;
1181 flags = n.flags;
1183 interrupted:
1184 /* If there were any pending addfd calls, clear them out */
1185 list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1186 /* The process went away before we got a chance to handle it */
1187 addfd->ret = -ESRCH;
1188 list_del_init(&addfd->list);
1189 complete(&addfd->completion);
1193 * Note that it's possible the listener died in between the time when
1194 * we were notified of a response (or a signal) and when we were able to
1195 * re-acquire the lock, so only delete from the list if the
1196 * notification actually exists.
1198 * Also note that this test is only valid because there's no way to
1199 * *reattach* to a notifier right now. If one is added, we'll need to
1200 * keep track of the notif itself and make sure they match here.
1202 if (match->notif)
1203 list_del(&n.list);
1204 out:
1205 mutex_unlock(&match->notify_lock);
1207 /* Userspace requests to continue the syscall. */
1208 if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1209 return 0;
1211 syscall_set_return_value(current, current_pt_regs(),
1212 err, ret);
1213 return -1;
1216 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1217 const bool recheck_after_trace)
1219 u32 filter_ret, action;
1220 struct seccomp_filter *match = NULL;
1221 int data;
1222 struct seccomp_data sd_local;
1225 * Make sure that any changes to mode from another thread have
1226 * been seen after SYSCALL_WORK_SECCOMP was seen.
1228 smp_rmb();
1230 if (!sd) {
1231 populate_seccomp_data(&sd_local);
1232 sd = &sd_local;
1235 filter_ret = seccomp_run_filters(sd, &match);
1236 data = filter_ret & SECCOMP_RET_DATA;
1237 action = filter_ret & SECCOMP_RET_ACTION_FULL;
1239 switch (action) {
1240 case SECCOMP_RET_ERRNO:
1241 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1242 if (data > MAX_ERRNO)
1243 data = MAX_ERRNO;
1244 syscall_set_return_value(current, current_pt_regs(),
1245 -data, 0);
1246 goto skip;
1248 case SECCOMP_RET_TRAP:
1249 /* Show the handler the original registers. */
1250 syscall_rollback(current, current_pt_regs());
1251 /* Let the filter pass back 16 bits of data. */
1252 force_sig_seccomp(this_syscall, data, false);
1253 goto skip;
1255 case SECCOMP_RET_TRACE:
1256 /* We've been put in this state by the ptracer already. */
1257 if (recheck_after_trace)
1258 return 0;
1260 /* ENOSYS these calls if there is no tracer attached. */
1261 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1262 syscall_set_return_value(current,
1263 current_pt_regs(),
1264 -ENOSYS, 0);
1265 goto skip;
1268 /* Allow the BPF to provide the event message */
1269 ptrace_event(PTRACE_EVENT_SECCOMP, data);
1271 * The delivery of a fatal signal during event
1272 * notification may silently skip tracer notification,
1273 * which could leave us with a potentially unmodified
1274 * syscall that the tracer would have liked to have
1275 * changed. Since the process is about to die, we just
1276 * force the syscall to be skipped and let the signal
1277 * kill the process and correctly handle any tracer exit
1278 * notifications.
1280 if (fatal_signal_pending(current))
1281 goto skip;
1282 /* Check if the tracer forced the syscall to be skipped. */
1283 this_syscall = syscall_get_nr(current, current_pt_regs());
1284 if (this_syscall < 0)
1285 goto skip;
1288 * Recheck the syscall, since it may have changed. This
1289 * intentionally uses a NULL struct seccomp_data to force
1290 * a reload of all registers. This does not goto skip since
1291 * a skip would have already been reported.
1293 if (__seccomp_filter(this_syscall, NULL, true))
1294 return -1;
1296 return 0;
1298 case SECCOMP_RET_USER_NOTIF:
1299 if (seccomp_do_user_notification(this_syscall, match, sd))
1300 goto skip;
1302 return 0;
1304 case SECCOMP_RET_LOG:
1305 seccomp_log(this_syscall, 0, action, true);
1306 return 0;
1308 case SECCOMP_RET_ALLOW:
1310 * Note that the "match" filter will always be NULL for
1311 * this action since SECCOMP_RET_ALLOW is the starting
1312 * state in seccomp_run_filters().
1314 return 0;
1316 case SECCOMP_RET_KILL_THREAD:
1317 case SECCOMP_RET_KILL_PROCESS:
1318 default:
1319 current->seccomp.mode = SECCOMP_MODE_DEAD;
1320 seccomp_log(this_syscall, SIGSYS, action, true);
1321 /* Dump core only if this is the last remaining thread. */
1322 if (action != SECCOMP_RET_KILL_THREAD ||
1323 (atomic_read(&current->signal->live) == 1)) {
1324 /* Show the original registers in the dump. */
1325 syscall_rollback(current, current_pt_regs());
1326 /* Trigger a coredump with SIGSYS */
1327 force_sig_seccomp(this_syscall, data, true);
1328 } else {
1329 do_exit(SIGSYS);
1331 return -1; /* skip the syscall go directly to signal handling */
1334 unreachable();
1336 skip:
1337 seccomp_log(this_syscall, 0, action, match ? match->log : false);
1338 return -1;
1340 #else
1341 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1342 const bool recheck_after_trace)
1344 BUG();
1346 return -1;
1348 #endif
1350 int __secure_computing(const struct seccomp_data *sd)
1352 int mode = current->seccomp.mode;
1353 int this_syscall;
1355 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1356 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1357 return 0;
1359 this_syscall = sd ? sd->nr :
1360 syscall_get_nr(current, current_pt_regs());
1362 switch (mode) {
1363 case SECCOMP_MODE_STRICT:
1364 __secure_computing_strict(this_syscall); /* may call do_exit */
1365 return 0;
1366 case SECCOMP_MODE_FILTER:
1367 return __seccomp_filter(this_syscall, sd, false);
1368 /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
1369 case SECCOMP_MODE_DEAD:
1370 WARN_ON_ONCE(1);
1371 do_exit(SIGKILL);
1372 return -1;
1373 default:
1374 BUG();
1377 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1379 long prctl_get_seccomp(void)
1381 return current->seccomp.mode;
1385 * seccomp_set_mode_strict: internal function for setting strict seccomp
1387 * Once current->seccomp.mode is non-zero, it may not be changed.
1389 * Returns 0 on success or -EINVAL on failure.
1391 static long seccomp_set_mode_strict(void)
1393 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1394 long ret = -EINVAL;
1396 spin_lock_irq(&current->sighand->siglock);
1398 if (!seccomp_may_assign_mode(seccomp_mode))
1399 goto out;
1401 #ifdef TIF_NOTSC
1402 disable_TSC();
1403 #endif
1404 seccomp_assign_mode(current, seccomp_mode, 0);
1405 ret = 0;
1407 out:
1408 spin_unlock_irq(&current->sighand->siglock);
1410 return ret;
1413 #ifdef CONFIG_SECCOMP_FILTER
1414 static void seccomp_notify_free(struct seccomp_filter *filter)
1416 kfree(filter->notif);
1417 filter->notif = NULL;
1420 static void seccomp_notify_detach(struct seccomp_filter *filter)
1422 struct seccomp_knotif *knotif;
1424 if (!filter)
1425 return;
1427 mutex_lock(&filter->notify_lock);
1430 * If this file is being closed because e.g. the task who owned it
1431 * died, let's wake everyone up who was waiting on us.
1433 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1434 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1435 continue;
1437 knotif->state = SECCOMP_NOTIFY_REPLIED;
1438 knotif->error = -ENOSYS;
1439 knotif->val = 0;
1442 * We do not need to wake up any pending addfd messages, as
1443 * the notifier will do that for us, as this just looks
1444 * like a standard reply.
1446 complete(&knotif->ready);
1449 seccomp_notify_free(filter);
1450 mutex_unlock(&filter->notify_lock);
1453 static int seccomp_notify_release(struct inode *inode, struct file *file)
1455 struct seccomp_filter *filter = file->private_data;
1457 seccomp_notify_detach(filter);
1458 __put_seccomp_filter(filter);
1459 return 0;
1462 /* must be called with notif_lock held */
1463 static inline struct seccomp_knotif *
1464 find_notification(struct seccomp_filter *filter, u64 id)
1466 struct seccomp_knotif *cur;
1468 lockdep_assert_held(&filter->notify_lock);
1470 list_for_each_entry(cur, &filter->notif->notifications, list) {
1471 if (cur->id == id)
1472 return cur;
1475 return NULL;
1478 static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync,
1479 void *key)
1481 /* Avoid a wakeup if event not interesting for us. */
1482 if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR | EPOLLHUP)))
1483 return 0;
1484 return autoremove_wake_function(wait, mode, sync, key);
1487 static int recv_wait_event(struct seccomp_filter *filter)
1489 DEFINE_WAIT_FUNC(wait, recv_wake_function);
1490 int ret;
1492 if (refcount_read(&filter->users) == 0)
1493 return 0;
1495 if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1496 return 0;
1498 for (;;) {
1499 ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE);
1501 if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1502 break;
1503 if (refcount_read(&filter->users) == 0)
1504 break;
1506 if (ret)
1507 return ret;
1509 schedule();
1511 finish_wait(&filter->wqh, &wait);
1512 return 0;
1515 static long seccomp_notify_recv(struct seccomp_filter *filter,
1516 void __user *buf)
1518 struct seccomp_knotif *knotif = NULL, *cur;
1519 struct seccomp_notif unotif;
1520 ssize_t ret;
1522 /* Verify that we're not given garbage to keep struct extensible. */
1523 ret = check_zeroed_user(buf, sizeof(unotif));
1524 if (ret < 0)
1525 return ret;
1526 if (!ret)
1527 return -EINVAL;
1529 memset(&unotif, 0, sizeof(unotif));
1531 ret = recv_wait_event(filter);
1532 if (ret < 0)
1533 return ret;
1535 mutex_lock(&filter->notify_lock);
1536 list_for_each_entry(cur, &filter->notif->notifications, list) {
1537 if (cur->state == SECCOMP_NOTIFY_INIT) {
1538 knotif = cur;
1539 break;
1544 * If we didn't find a notification, it could be that the task was
1545 * interrupted by a fatal signal between the time we were woken and
1546 * when we were able to acquire the rw lock.
1548 if (!knotif) {
1549 ret = -ENOENT;
1550 goto out;
1553 unotif.id = knotif->id;
1554 unotif.pid = task_pid_vnr(knotif->task);
1555 unotif.data = *(knotif->data);
1557 knotif->state = SECCOMP_NOTIFY_SENT;
1558 wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1559 ret = 0;
1560 out:
1561 mutex_unlock(&filter->notify_lock);
1563 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1564 ret = -EFAULT;
1567 * Userspace screwed up. To make sure that we keep this
1568 * notification alive, let's reset it back to INIT. It
1569 * may have died when we released the lock, so we need to make
1570 * sure it's still around.
1572 mutex_lock(&filter->notify_lock);
1573 knotif = find_notification(filter, unotif.id);
1574 if (knotif) {
1575 /* Reset the process to make sure it's not stuck */
1576 if (should_sleep_killable(filter, knotif))
1577 complete(&knotif->ready);
1578 knotif->state = SECCOMP_NOTIFY_INIT;
1579 atomic_inc(&filter->notif->requests);
1580 wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM);
1582 mutex_unlock(&filter->notify_lock);
1585 return ret;
1588 static long seccomp_notify_send(struct seccomp_filter *filter,
1589 void __user *buf)
1591 struct seccomp_notif_resp resp = {};
1592 struct seccomp_knotif *knotif;
1593 long ret;
1595 if (copy_from_user(&resp, buf, sizeof(resp)))
1596 return -EFAULT;
1598 if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1599 return -EINVAL;
1601 if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1602 (resp.error || resp.val))
1603 return -EINVAL;
1605 ret = mutex_lock_interruptible(&filter->notify_lock);
1606 if (ret < 0)
1607 return ret;
1609 knotif = find_notification(filter, resp.id);
1610 if (!knotif) {
1611 ret = -ENOENT;
1612 goto out;
1615 /* Allow exactly one reply. */
1616 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1617 ret = -EINPROGRESS;
1618 goto out;
1621 ret = 0;
1622 knotif->state = SECCOMP_NOTIFY_REPLIED;
1623 knotif->error = resp.error;
1624 knotif->val = resp.val;
1625 knotif->flags = resp.flags;
1626 if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1627 complete_on_current_cpu(&knotif->ready);
1628 else
1629 complete(&knotif->ready);
1630 out:
1631 mutex_unlock(&filter->notify_lock);
1632 return ret;
1635 static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1636 void __user *buf)
1638 struct seccomp_knotif *knotif;
1639 u64 id;
1640 long ret;
1642 if (copy_from_user(&id, buf, sizeof(id)))
1643 return -EFAULT;
1645 ret = mutex_lock_interruptible(&filter->notify_lock);
1646 if (ret < 0)
1647 return ret;
1649 knotif = find_notification(filter, id);
1650 if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1651 ret = 0;
1652 else
1653 ret = -ENOENT;
1655 mutex_unlock(&filter->notify_lock);
1656 return ret;
1659 static long seccomp_notify_set_flags(struct seccomp_filter *filter,
1660 unsigned long flags)
1662 long ret;
1664 if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1665 return -EINVAL;
1667 ret = mutex_lock_interruptible(&filter->notify_lock);
1668 if (ret < 0)
1669 return ret;
1670 filter->notif->flags = flags;
1671 mutex_unlock(&filter->notify_lock);
1672 return 0;
1675 static long seccomp_notify_addfd(struct seccomp_filter *filter,
1676 struct seccomp_notif_addfd __user *uaddfd,
1677 unsigned int size)
1679 struct seccomp_notif_addfd addfd;
1680 struct seccomp_knotif *knotif;
1681 struct seccomp_kaddfd kaddfd;
1682 int ret;
1684 BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1685 BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1687 if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1688 return -EINVAL;
1690 ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1691 if (ret)
1692 return ret;
1694 if (addfd.newfd_flags & ~O_CLOEXEC)
1695 return -EINVAL;
1697 if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
1698 return -EINVAL;
1700 if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1701 return -EINVAL;
1703 kaddfd.file = fget(addfd.srcfd);
1704 if (!kaddfd.file)
1705 return -EBADF;
1707 kaddfd.ioctl_flags = addfd.flags;
1708 kaddfd.flags = addfd.newfd_flags;
1709 kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1710 kaddfd.fd = addfd.newfd;
1711 init_completion(&kaddfd.completion);
1713 ret = mutex_lock_interruptible(&filter->notify_lock);
1714 if (ret < 0)
1715 goto out;
1717 knotif = find_notification(filter, addfd.id);
1718 if (!knotif) {
1719 ret = -ENOENT;
1720 goto out_unlock;
1724 * We do not want to allow for FD injection to occur before the
1725 * notification has been picked up by a userspace handler, or after
1726 * the notification has been replied to.
1728 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1729 ret = -EINPROGRESS;
1730 goto out_unlock;
1733 if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
1735 * Disallow queuing an atomic addfd + send reply while there are
1736 * some addfd requests still to process.
1738 * There is no clear reason to support it and allows us to keep
1739 * the loop on the other side straight-forward.
1741 if (!list_empty(&knotif->addfd)) {
1742 ret = -EBUSY;
1743 goto out_unlock;
1746 /* Allow exactly only one reply */
1747 knotif->state = SECCOMP_NOTIFY_REPLIED;
1750 list_add(&kaddfd.list, &knotif->addfd);
1751 complete(&knotif->ready);
1752 mutex_unlock(&filter->notify_lock);
1754 /* Now we wait for it to be processed or be interrupted */
1755 ret = wait_for_completion_interruptible(&kaddfd.completion);
1756 if (ret == 0) {
1758 * We had a successful completion. The other side has already
1759 * removed us from the addfd queue, and
1760 * wait_for_completion_interruptible has a memory barrier upon
1761 * success that lets us read this value directly without
1762 * locking.
1764 ret = kaddfd.ret;
1765 goto out;
1768 mutex_lock(&filter->notify_lock);
1770 * Even though we were woken up by a signal and not a successful
1771 * completion, a completion may have happened in the mean time.
1773 * We need to check again if the addfd request has been handled,
1774 * and if not, we will remove it from the queue.
1776 if (list_empty(&kaddfd.list))
1777 ret = kaddfd.ret;
1778 else
1779 list_del(&kaddfd.list);
1781 out_unlock:
1782 mutex_unlock(&filter->notify_lock);
1783 out:
1784 fput(kaddfd.file);
1786 return ret;
1789 static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1790 unsigned long arg)
1792 struct seccomp_filter *filter = file->private_data;
1793 void __user *buf = (void __user *)arg;
1795 /* Fixed-size ioctls */
1796 switch (cmd) {
1797 case SECCOMP_IOCTL_NOTIF_RECV:
1798 return seccomp_notify_recv(filter, buf);
1799 case SECCOMP_IOCTL_NOTIF_SEND:
1800 return seccomp_notify_send(filter, buf);
1801 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1802 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1803 return seccomp_notify_id_valid(filter, buf);
1804 case SECCOMP_IOCTL_NOTIF_SET_FLAGS:
1805 return seccomp_notify_set_flags(filter, arg);
1808 /* Extensible Argument ioctls */
1809 #define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1810 switch (EA_IOCTL(cmd)) {
1811 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1812 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1813 default:
1814 return -EINVAL;
1818 static __poll_t seccomp_notify_poll(struct file *file,
1819 struct poll_table_struct *poll_tab)
1821 struct seccomp_filter *filter = file->private_data;
1822 __poll_t ret = 0;
1823 struct seccomp_knotif *cur;
1825 poll_wait(file, &filter->wqh, poll_tab);
1827 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1828 return EPOLLERR;
1830 list_for_each_entry(cur, &filter->notif->notifications, list) {
1831 if (cur->state == SECCOMP_NOTIFY_INIT)
1832 ret |= EPOLLIN | EPOLLRDNORM;
1833 if (cur->state == SECCOMP_NOTIFY_SENT)
1834 ret |= EPOLLOUT | EPOLLWRNORM;
1835 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1836 break;
1839 mutex_unlock(&filter->notify_lock);
1841 if (refcount_read(&filter->users) == 0)
1842 ret |= EPOLLHUP;
1844 return ret;
1847 static const struct file_operations seccomp_notify_ops = {
1848 .poll = seccomp_notify_poll,
1849 .release = seccomp_notify_release,
1850 .unlocked_ioctl = seccomp_notify_ioctl,
1851 .compat_ioctl = seccomp_notify_ioctl,
1854 static struct file *init_listener(struct seccomp_filter *filter)
1856 struct file *ret;
1858 ret = ERR_PTR(-ENOMEM);
1859 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1860 if (!filter->notif)
1861 goto out;
1863 filter->notif->next_id = get_random_u64();
1864 INIT_LIST_HEAD(&filter->notif->notifications);
1866 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1867 filter, O_RDWR);
1868 if (IS_ERR(ret))
1869 goto out_notif;
1871 /* The file has a reference to it now */
1872 __get_seccomp_filter(filter);
1874 out_notif:
1875 if (IS_ERR(ret))
1876 seccomp_notify_free(filter);
1877 out:
1878 return ret;
1882 * Does @new_child have a listener while an ancestor also has a listener?
1883 * If so, we'll want to reject this filter.
1884 * This only has to be tested for the current process, even in the TSYNC case,
1885 * because TSYNC installs @child with the same parent on all threads.
1886 * Note that @new_child is not hooked up to its parent at this point yet, so
1887 * we use current->seccomp.filter.
1889 static bool has_duplicate_listener(struct seccomp_filter *new_child)
1891 struct seccomp_filter *cur;
1893 /* must be protected against concurrent TSYNC */
1894 lockdep_assert_held(&current->sighand->siglock);
1896 if (!new_child->notif)
1897 return false;
1898 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1899 if (cur->notif)
1900 return true;
1903 return false;
1907 * seccomp_set_mode_filter: internal function for setting seccomp filter
1908 * @flags: flags to change filter behavior
1909 * @filter: struct sock_fprog containing filter
1911 * This function may be called repeatedly to install additional filters.
1912 * Every filter successfully installed will be evaluated (in reverse order)
1913 * for each system call the task makes.
1915 * Once current->seccomp.mode is non-zero, it may not be changed.
1917 * Returns 0 on success or -EINVAL on failure.
1919 static long seccomp_set_mode_filter(unsigned int flags,
1920 const char __user *filter)
1922 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1923 struct seccomp_filter *prepared = NULL;
1924 long ret = -EINVAL;
1925 int listener = -1;
1926 struct file *listener_f = NULL;
1928 /* Validate flags. */
1929 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1930 return -EINVAL;
1933 * In the successful case, NEW_LISTENER returns the new listener fd.
1934 * But in the failure case, TSYNC returns the thread that died. If you
1935 * combine these two flags, there's no way to tell whether something
1936 * succeeded or failed. So, let's disallow this combination if the user
1937 * has not explicitly requested no errors from TSYNC.
1939 if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1940 (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1941 ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1942 return -EINVAL;
1945 * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
1946 * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
1948 if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
1949 ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
1950 return -EINVAL;
1952 /* Prepare the new filter before holding any locks. */
1953 prepared = seccomp_prepare_user_filter(filter);
1954 if (IS_ERR(prepared))
1955 return PTR_ERR(prepared);
1957 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1958 listener = get_unused_fd_flags(O_CLOEXEC);
1959 if (listener < 0) {
1960 ret = listener;
1961 goto out_free;
1964 listener_f = init_listener(prepared);
1965 if (IS_ERR(listener_f)) {
1966 put_unused_fd(listener);
1967 ret = PTR_ERR(listener_f);
1968 goto out_free;
1973 * Make sure we cannot change seccomp or nnp state via TSYNC
1974 * while another thread is in the middle of calling exec.
1976 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1977 mutex_lock_killable(&current->signal->cred_guard_mutex))
1978 goto out_put_fd;
1980 spin_lock_irq(&current->sighand->siglock);
1982 if (!seccomp_may_assign_mode(seccomp_mode))
1983 goto out;
1985 if (has_duplicate_listener(prepared)) {
1986 ret = -EBUSY;
1987 goto out;
1990 ret = seccomp_attach_filter(flags, prepared);
1991 if (ret)
1992 goto out;
1993 /* Do not free the successfully attached filter. */
1994 prepared = NULL;
1996 seccomp_assign_mode(current, seccomp_mode, flags);
1997 out:
1998 spin_unlock_irq(&current->sighand->siglock);
1999 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
2000 mutex_unlock(&current->signal->cred_guard_mutex);
2001 out_put_fd:
2002 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
2003 if (ret) {
2004 listener_f->private_data = NULL;
2005 fput(listener_f);
2006 put_unused_fd(listener);
2007 seccomp_notify_detach(prepared);
2008 } else {
2009 fd_install(listener, listener_f);
2010 ret = listener;
2013 out_free:
2014 seccomp_filter_free(prepared);
2015 return ret;
2017 #else
2018 static inline long seccomp_set_mode_filter(unsigned int flags,
2019 const char __user *filter)
2021 return -EINVAL;
2023 #endif
2025 static long seccomp_get_action_avail(const char __user *uaction)
2027 u32 action;
2029 if (copy_from_user(&action, uaction, sizeof(action)))
2030 return -EFAULT;
2032 switch (action) {
2033 case SECCOMP_RET_KILL_PROCESS:
2034 case SECCOMP_RET_KILL_THREAD:
2035 case SECCOMP_RET_TRAP:
2036 case SECCOMP_RET_ERRNO:
2037 case SECCOMP_RET_USER_NOTIF:
2038 case SECCOMP_RET_TRACE:
2039 case SECCOMP_RET_LOG:
2040 case SECCOMP_RET_ALLOW:
2041 break;
2042 default:
2043 return -EOPNOTSUPP;
2046 return 0;
2049 static long seccomp_get_notif_sizes(void __user *usizes)
2051 struct seccomp_notif_sizes sizes = {
2052 .seccomp_notif = sizeof(struct seccomp_notif),
2053 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
2054 .seccomp_data = sizeof(struct seccomp_data),
2057 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
2058 return -EFAULT;
2060 return 0;
2063 /* Common entry point for both prctl and syscall. */
2064 static long do_seccomp(unsigned int op, unsigned int flags,
2065 void __user *uargs)
2067 switch (op) {
2068 case SECCOMP_SET_MODE_STRICT:
2069 if (flags != 0 || uargs != NULL)
2070 return -EINVAL;
2071 return seccomp_set_mode_strict();
2072 case SECCOMP_SET_MODE_FILTER:
2073 return seccomp_set_mode_filter(flags, uargs);
2074 case SECCOMP_GET_ACTION_AVAIL:
2075 if (flags != 0)
2076 return -EINVAL;
2078 return seccomp_get_action_avail(uargs);
2079 case SECCOMP_GET_NOTIF_SIZES:
2080 if (flags != 0)
2081 return -EINVAL;
2083 return seccomp_get_notif_sizes(uargs);
2084 default:
2085 return -EINVAL;
2089 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
2090 void __user *, uargs)
2092 return do_seccomp(op, flags, uargs);
2096 * prctl_set_seccomp: configures current->seccomp.mode
2097 * @seccomp_mode: requested mode to use
2098 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2100 * Returns 0 on success or -EINVAL on failure.
2102 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
2104 unsigned int op;
2105 void __user *uargs;
2107 switch (seccomp_mode) {
2108 case SECCOMP_MODE_STRICT:
2109 op = SECCOMP_SET_MODE_STRICT;
2111 * Setting strict mode through prctl always ignored filter,
2112 * so make sure it is always NULL here to pass the internal
2113 * check in do_seccomp().
2115 uargs = NULL;
2116 break;
2117 case SECCOMP_MODE_FILTER:
2118 op = SECCOMP_SET_MODE_FILTER;
2119 uargs = filter;
2120 break;
2121 default:
2122 return -EINVAL;
2125 /* prctl interface doesn't have flags, so they are always zero. */
2126 return do_seccomp(op, 0, uargs);
2129 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
2130 static struct seccomp_filter *get_nth_filter(struct task_struct *task,
2131 unsigned long filter_off)
2133 struct seccomp_filter *orig, *filter;
2134 unsigned long count;
2137 * Note: this is only correct because the caller should be the (ptrace)
2138 * tracer of the task, otherwise lock_task_sighand is needed.
2140 spin_lock_irq(&task->sighand->siglock);
2142 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2143 spin_unlock_irq(&task->sighand->siglock);
2144 return ERR_PTR(-EINVAL);
2147 orig = task->seccomp.filter;
2148 __get_seccomp_filter(orig);
2149 spin_unlock_irq(&task->sighand->siglock);
2151 count = 0;
2152 for (filter = orig; filter; filter = filter->prev)
2153 count++;
2155 if (filter_off >= count) {
2156 filter = ERR_PTR(-ENOENT);
2157 goto out;
2160 count -= filter_off;
2161 for (filter = orig; filter && count > 1; filter = filter->prev)
2162 count--;
2164 if (WARN_ON(count != 1 || !filter)) {
2165 filter = ERR_PTR(-ENOENT);
2166 goto out;
2169 __get_seccomp_filter(filter);
2171 out:
2172 __put_seccomp_filter(orig);
2173 return filter;
2176 long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2177 void __user *data)
2179 struct seccomp_filter *filter;
2180 struct sock_fprog_kern *fprog;
2181 long ret;
2183 if (!capable(CAP_SYS_ADMIN) ||
2184 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2185 return -EACCES;
2188 filter = get_nth_filter(task, filter_off);
2189 if (IS_ERR(filter))
2190 return PTR_ERR(filter);
2192 fprog = filter->prog->orig_prog;
2193 if (!fprog) {
2194 /* This must be a new non-cBPF filter, since we save
2195 * every cBPF filter's orig_prog above when
2196 * CONFIG_CHECKPOINT_RESTORE is enabled.
2198 ret = -EMEDIUMTYPE;
2199 goto out;
2202 ret = fprog->len;
2203 if (!data)
2204 goto out;
2206 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2207 ret = -EFAULT;
2209 out:
2210 __put_seccomp_filter(filter);
2211 return ret;
2214 long seccomp_get_metadata(struct task_struct *task,
2215 unsigned long size, void __user *data)
2217 long ret;
2218 struct seccomp_filter *filter;
2219 struct seccomp_metadata kmd = {};
2221 if (!capable(CAP_SYS_ADMIN) ||
2222 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2223 return -EACCES;
2226 size = min_t(unsigned long, size, sizeof(kmd));
2228 if (size < sizeof(kmd.filter_off))
2229 return -EINVAL;
2231 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2232 return -EFAULT;
2234 filter = get_nth_filter(task, kmd.filter_off);
2235 if (IS_ERR(filter))
2236 return PTR_ERR(filter);
2238 if (filter->log)
2239 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2241 ret = size;
2242 if (copy_to_user(data, &kmd, size))
2243 ret = -EFAULT;
2245 __put_seccomp_filter(filter);
2246 return ret;
2248 #endif
2250 #ifdef CONFIG_SYSCTL
2252 /* Human readable action names for friendly sysctl interaction */
2253 #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
2254 #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
2255 #define SECCOMP_RET_TRAP_NAME "trap"
2256 #define SECCOMP_RET_ERRNO_NAME "errno"
2257 #define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
2258 #define SECCOMP_RET_TRACE_NAME "trace"
2259 #define SECCOMP_RET_LOG_NAME "log"
2260 #define SECCOMP_RET_ALLOW_NAME "allow"
2262 static const char seccomp_actions_avail[] =
2263 SECCOMP_RET_KILL_PROCESS_NAME " "
2264 SECCOMP_RET_KILL_THREAD_NAME " "
2265 SECCOMP_RET_TRAP_NAME " "
2266 SECCOMP_RET_ERRNO_NAME " "
2267 SECCOMP_RET_USER_NOTIF_NAME " "
2268 SECCOMP_RET_TRACE_NAME " "
2269 SECCOMP_RET_LOG_NAME " "
2270 SECCOMP_RET_ALLOW_NAME;
2272 struct seccomp_log_name {
2273 u32 log;
2274 const char *name;
2277 static const struct seccomp_log_name seccomp_log_names[] = {
2278 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2279 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2280 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2281 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2282 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2283 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2284 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2285 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2289 static bool seccomp_names_from_actions_logged(char *names, size_t size,
2290 u32 actions_logged,
2291 const char *sep)
2293 const struct seccomp_log_name *cur;
2294 bool append_sep = false;
2296 for (cur = seccomp_log_names; cur->name && size; cur++) {
2297 ssize_t ret;
2299 if (!(actions_logged & cur->log))
2300 continue;
2302 if (append_sep) {
2303 ret = strscpy(names, sep, size);
2304 if (ret < 0)
2305 return false;
2307 names += ret;
2308 size -= ret;
2309 } else
2310 append_sep = true;
2312 ret = strscpy(names, cur->name, size);
2313 if (ret < 0)
2314 return false;
2316 names += ret;
2317 size -= ret;
2320 return true;
2323 static bool seccomp_action_logged_from_name(u32 *action_logged,
2324 const char *name)
2326 const struct seccomp_log_name *cur;
2328 for (cur = seccomp_log_names; cur->name; cur++) {
2329 if (!strcmp(cur->name, name)) {
2330 *action_logged = cur->log;
2331 return true;
2335 return false;
2338 static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2340 char *name;
2342 *actions_logged = 0;
2343 while ((name = strsep(&names, " ")) && *name) {
2344 u32 action_logged = 0;
2346 if (!seccomp_action_logged_from_name(&action_logged, name))
2347 return false;
2349 *actions_logged |= action_logged;
2352 return true;
2355 static int read_actions_logged(const struct ctl_table *ro_table, void *buffer,
2356 size_t *lenp, loff_t *ppos)
2358 char names[sizeof(seccomp_actions_avail)];
2359 struct ctl_table table;
2361 memset(names, 0, sizeof(names));
2363 if (!seccomp_names_from_actions_logged(names, sizeof(names),
2364 seccomp_actions_logged, " "))
2365 return -EINVAL;
2367 table = *ro_table;
2368 table.data = names;
2369 table.maxlen = sizeof(names);
2370 return proc_dostring(&table, 0, buffer, lenp, ppos);
2373 static int write_actions_logged(const struct ctl_table *ro_table, void *buffer,
2374 size_t *lenp, loff_t *ppos, u32 *actions_logged)
2376 char names[sizeof(seccomp_actions_avail)];
2377 struct ctl_table table;
2378 int ret;
2380 if (!capable(CAP_SYS_ADMIN))
2381 return -EPERM;
2383 memset(names, 0, sizeof(names));
2385 table = *ro_table;
2386 table.data = names;
2387 table.maxlen = sizeof(names);
2388 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2389 if (ret)
2390 return ret;
2392 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2393 return -EINVAL;
2395 if (*actions_logged & SECCOMP_LOG_ALLOW)
2396 return -EINVAL;
2398 seccomp_actions_logged = *actions_logged;
2399 return 0;
2402 static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2403 int ret)
2405 char names[sizeof(seccomp_actions_avail)];
2406 char old_names[sizeof(seccomp_actions_avail)];
2407 const char *new = names;
2408 const char *old = old_names;
2410 if (!audit_enabled)
2411 return;
2413 memset(names, 0, sizeof(names));
2414 memset(old_names, 0, sizeof(old_names));
2416 if (ret)
2417 new = "?";
2418 else if (!actions_logged)
2419 new = "(none)";
2420 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2421 actions_logged, ","))
2422 new = "?";
2424 if (!old_actions_logged)
2425 old = "(none)";
2426 else if (!seccomp_names_from_actions_logged(old_names,
2427 sizeof(old_names),
2428 old_actions_logged, ","))
2429 old = "?";
2431 return audit_seccomp_actions_logged(new, old, !ret);
2434 static int seccomp_actions_logged_handler(const struct ctl_table *ro_table, int write,
2435 void *buffer, size_t *lenp,
2436 loff_t *ppos)
2438 int ret;
2440 if (write) {
2441 u32 actions_logged = 0;
2442 u32 old_actions_logged = seccomp_actions_logged;
2444 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2445 &actions_logged);
2446 audit_actions_logged(actions_logged, old_actions_logged, ret);
2447 } else
2448 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2450 return ret;
2453 static struct ctl_table seccomp_sysctl_table[] = {
2455 .procname = "actions_avail",
2456 .data = (void *) &seccomp_actions_avail,
2457 .maxlen = sizeof(seccomp_actions_avail),
2458 .mode = 0444,
2459 .proc_handler = proc_dostring,
2462 .procname = "actions_logged",
2463 .mode = 0644,
2464 .proc_handler = seccomp_actions_logged_handler,
2468 static int __init seccomp_sysctl_init(void)
2470 register_sysctl_init("kernel/seccomp", seccomp_sysctl_table);
2471 return 0;
2474 device_initcall(seccomp_sysctl_init)
2476 #endif /* CONFIG_SYSCTL */
2478 #ifdef CONFIG_SECCOMP_CACHE_DEBUG
2479 /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2480 static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2481 const void *bitmap, size_t bitmap_size)
2483 int nr;
2485 for (nr = 0; nr < bitmap_size; nr++) {
2486 bool cached = test_bit(nr, bitmap);
2487 char *status = cached ? "ALLOW" : "FILTER";
2489 seq_printf(m, "%s %d %s\n", name, nr, status);
2493 int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2494 struct pid *pid, struct task_struct *task)
2496 struct seccomp_filter *f;
2497 unsigned long flags;
2500 * We don't want some sandboxed process to know what their seccomp
2501 * filters consist of.
2503 if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2504 return -EACCES;
2506 if (!lock_task_sighand(task, &flags))
2507 return -ESRCH;
2509 f = READ_ONCE(task->seccomp.filter);
2510 if (!f) {
2511 unlock_task_sighand(task, &flags);
2512 return 0;
2515 /* prevent filter from being freed while we are printing it */
2516 __get_seccomp_filter(f);
2517 unlock_task_sighand(task, &flags);
2519 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2520 f->cache.allow_native,
2521 SECCOMP_ARCH_NATIVE_NR);
2523 #ifdef SECCOMP_ARCH_COMPAT
2524 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2525 f->cache.allow_compat,
2526 SECCOMP_ARCH_COMPAT_NR);
2527 #endif /* SECCOMP_ARCH_COMPAT */
2529 __put_seccomp_filter(f);
2530 return 0;
2532 #endif /* CONFIG_SECCOMP_CACHE_DEBUG */