1 // SPDX-License-Identifier: GPL-2.0
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 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
33 #include <asm/syscall.h>
36 #ifdef CONFIG_SECCOMP_FILTER
37 #include <linux/file.h>
38 #include <linux/filter.h>
39 #include <linux/pid.h>
40 #include <linux/ptrace.h>
41 #include <linux/capability.h>
42 #include <linux/tracehook.h>
43 #include <linux/uaccess.h>
44 #include <linux/anon_inodes.h>
45 #include <linux/lockdep.h>
48 * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
49 * wrong direction flag in the ioctl number. This is the broken one,
50 * which the kernel needs to keep supporting until all userspaces stop
51 * using the wrong command number.
53 #define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
58 SECCOMP_NOTIFY_REPLIED,
61 struct seccomp_knotif {
62 /* The struct pid of the task whose filter triggered the notification */
63 struct task_struct *task;
65 /* The "cookie" for this request; this is unique for this filter. */
69 * The seccomp data. This pointer is valid the entire time this
70 * notification is active, since it comes from __seccomp_filter which
71 * eclipses the entire lifecycle here.
73 const struct seccomp_data *data;
76 * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
77 * struct seccomp_knotif is created and starts out in INIT. Once the
78 * handler reads the notification off of an FD, it transitions to SENT.
79 * If a signal is received the state transitions back to INIT and
80 * another message is sent. When the userspace handler replies, state
81 * transitions to REPLIED.
83 enum notify_state state;
85 /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
91 * Signals when this has changed states, such as the listener
92 * dying, a new seccomp addfd message, or changing to REPLIED
94 struct completion ready;
96 struct list_head list;
98 /* outstanding addfd requests */
99 struct list_head addfd;
103 * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
105 * @file: A reference to the file to install in the other task
106 * @fd: The fd number to install it at. If the fd number is -1, it means the
107 * installing process should allocate the fd as normal.
108 * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
110 * @ret: The return value of the installing process. It is set to the fd num
111 * upon success (>= 0).
112 * @completion: Indicates that the installing process has completed fd
113 * installation, or gone away (either due to successful
117 struct seccomp_kaddfd {
124 /* To only be set on reply */
127 struct completion completion;
128 struct list_head list;
132 * struct notification - container for seccomp userspace notifications. Since
133 * most seccomp filters will not have notification listeners attached and this
134 * structure is fairly large, we store the notification-specific stuff in a
135 * separate structure.
137 * @request: A semaphore that users of this notification can wait on for
138 * changes. Actual reads and writes are still controlled with
139 * filter->notify_lock.
140 * @next_id: The id of the next request.
141 * @notifications: A list of struct seccomp_knotif elements.
143 struct notification {
144 struct semaphore request;
146 struct list_head notifications;
149 #ifdef SECCOMP_ARCH_NATIVE
151 * struct action_cache - per-filter cache of seccomp actions per
154 * @allow_native: A bitmap where each bit represents whether the
155 * filter will always allow the syscall, for the
156 * native architecture.
157 * @allow_compat: A bitmap where each bit represents whether the
158 * filter will always allow the syscall, for the
159 * compat architecture.
161 struct action_cache {
162 DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
163 #ifdef SECCOMP_ARCH_COMPAT
164 DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
168 struct action_cache { };
170 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
171 const struct seccomp_data *sd)
176 static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
179 #endif /* SECCOMP_ARCH_NATIVE */
182 * struct seccomp_filter - container for seccomp BPF programs
184 * @refs: Reference count to manage the object lifetime.
185 * A filter's reference count is incremented for each directly
186 * attached task, once for the dependent filter, and if
187 * requested for the user notifier. When @refs reaches zero,
188 * the filter can be freed.
189 * @users: A filter's @users count is incremented for each directly
190 * attached task (filter installation, fork(), thread_sync),
191 * and once for the dependent filter (tracked in filter->prev).
192 * When it reaches zero it indicates that no direct or indirect
193 * users of that filter exist. No new tasks can get associated with
194 * this filter after reaching 0. The @users count is always smaller
195 * or equal to @refs. Hence, reaching 0 for @users does not mean
196 * the filter can be freed.
197 * @cache: cache of arch/syscall mappings to actions
198 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
199 * @prev: points to a previously installed, or inherited, filter
200 * @prog: the BPF program to evaluate
201 * @notif: the struct that holds all notification related information
202 * @notify_lock: A lock for all notification-related accesses.
203 * @wqh: A wait queue for poll if a notifier is in use.
205 * seccomp_filter objects are organized in a tree linked via the @prev
206 * pointer. For any task, it appears to be a singly-linked list starting
207 * with current->seccomp.filter, the most recently attached or inherited filter.
208 * However, multiple filters may share a @prev node, by way of fork(), which
209 * results in a unidirectional tree existing in memory. This is similar to
210 * how namespaces work.
212 * seccomp_filter objects should never be modified after being attached
213 * to a task_struct (other than @refs).
215 struct seccomp_filter {
219 struct action_cache cache;
220 struct seccomp_filter *prev;
221 struct bpf_prog *prog;
222 struct notification *notif;
223 struct mutex notify_lock;
224 wait_queue_head_t wqh;
227 /* Limit any path through the tree to 256KB worth of instructions. */
228 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
231 * Endianness is explicitly ignored and left for BPF program authors to manage
232 * as per the specific architecture.
234 static void populate_seccomp_data(struct seccomp_data *sd)
237 * Instead of using current_pt_reg(), we're already doing the work
238 * to safely fetch "current", so just use "task" everywhere below.
240 struct task_struct *task = current;
241 struct pt_regs *regs = task_pt_regs(task);
242 unsigned long args[6];
244 sd->nr = syscall_get_nr(task, regs);
245 sd->arch = syscall_get_arch(task);
246 syscall_get_arguments(task, regs, args);
247 sd->args[0] = args[0];
248 sd->args[1] = args[1];
249 sd->args[2] = args[2];
250 sd->args[3] = args[3];
251 sd->args[4] = args[4];
252 sd->args[5] = args[5];
253 sd->instruction_pointer = KSTK_EIP(task);
257 * seccomp_check_filter - verify seccomp filter code
258 * @filter: filter to verify
259 * @flen: length of filter
261 * Takes a previously checked filter (by bpf_check_classic) and
262 * redirects all filter code that loads struct sk_buff data
263 * and related data through seccomp_bpf_load. It also
264 * enforces length and alignment checking of those loads.
266 * Returns 0 if the rule set is legal or -EINVAL if not.
268 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
271 for (pc = 0; pc < flen; pc++) {
272 struct sock_filter *ftest = &filter[pc];
273 u16 code = ftest->code;
277 case BPF_LD | BPF_W | BPF_ABS:
278 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
279 /* 32-bit aligned and not out of bounds. */
280 if (k >= sizeof(struct seccomp_data) || k & 3)
283 case BPF_LD | BPF_W | BPF_LEN:
284 ftest->code = BPF_LD | BPF_IMM;
285 ftest->k = sizeof(struct seccomp_data);
287 case BPF_LDX | BPF_W | BPF_LEN:
288 ftest->code = BPF_LDX | BPF_IMM;
289 ftest->k = sizeof(struct seccomp_data);
291 /* Explicitly include allowed calls. */
292 case BPF_RET | BPF_K:
293 case BPF_RET | BPF_A:
294 case BPF_ALU | BPF_ADD | BPF_K:
295 case BPF_ALU | BPF_ADD | BPF_X:
296 case BPF_ALU | BPF_SUB | BPF_K:
297 case BPF_ALU | BPF_SUB | BPF_X:
298 case BPF_ALU | BPF_MUL | BPF_K:
299 case BPF_ALU | BPF_MUL | BPF_X:
300 case BPF_ALU | BPF_DIV | BPF_K:
301 case BPF_ALU | BPF_DIV | BPF_X:
302 case BPF_ALU | BPF_AND | BPF_K:
303 case BPF_ALU | BPF_AND | BPF_X:
304 case BPF_ALU | BPF_OR | BPF_K:
305 case BPF_ALU | BPF_OR | BPF_X:
306 case BPF_ALU | BPF_XOR | BPF_K:
307 case BPF_ALU | BPF_XOR | BPF_X:
308 case BPF_ALU | BPF_LSH | BPF_K:
309 case BPF_ALU | BPF_LSH | BPF_X:
310 case BPF_ALU | BPF_RSH | BPF_K:
311 case BPF_ALU | BPF_RSH | BPF_X:
312 case BPF_ALU | BPF_NEG:
313 case BPF_LD | BPF_IMM:
314 case BPF_LDX | BPF_IMM:
315 case BPF_MISC | BPF_TAX:
316 case BPF_MISC | BPF_TXA:
317 case BPF_LD | BPF_MEM:
318 case BPF_LDX | BPF_MEM:
321 case BPF_JMP | BPF_JA:
322 case BPF_JMP | BPF_JEQ | BPF_K:
323 case BPF_JMP | BPF_JEQ | BPF_X:
324 case BPF_JMP | BPF_JGE | BPF_K:
325 case BPF_JMP | BPF_JGE | BPF_X:
326 case BPF_JMP | BPF_JGT | BPF_K:
327 case BPF_JMP | BPF_JGT | BPF_X:
328 case BPF_JMP | BPF_JSET | BPF_K:
329 case BPF_JMP | BPF_JSET | BPF_X:
338 #ifdef SECCOMP_ARCH_NATIVE
339 static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
343 if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
345 syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
347 return test_bit(syscall_nr, bitmap);
351 * seccomp_cache_check_allow - lookup seccomp cache
352 * @sfilter: The seccomp filter
353 * @sd: The seccomp data to lookup the cache with
355 * Returns true if the seccomp_data is cached and allowed.
357 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
358 const struct seccomp_data *sd)
360 int syscall_nr = sd->nr;
361 const struct action_cache *cache = &sfilter->cache;
363 #ifndef SECCOMP_ARCH_COMPAT
364 /* A native-only architecture doesn't need to check sd->arch. */
365 return seccomp_cache_check_allow_bitmap(cache->allow_native,
366 SECCOMP_ARCH_NATIVE_NR,
369 if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
370 return seccomp_cache_check_allow_bitmap(cache->allow_native,
371 SECCOMP_ARCH_NATIVE_NR,
373 if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
374 return seccomp_cache_check_allow_bitmap(cache->allow_compat,
375 SECCOMP_ARCH_COMPAT_NR,
377 #endif /* SECCOMP_ARCH_COMPAT */
382 #endif /* SECCOMP_ARCH_NATIVE */
385 * seccomp_run_filters - evaluates all seccomp filters against @sd
386 * @sd: optional seccomp data to be passed to filters
387 * @match: stores struct seccomp_filter that resulted in the return value,
388 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
391 * Returns valid seccomp BPF response codes.
393 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
394 static u32 seccomp_run_filters(const struct seccomp_data *sd,
395 struct seccomp_filter **match)
397 u32 ret = SECCOMP_RET_ALLOW;
398 /* Make sure cross-thread synced filter points somewhere sane. */
399 struct seccomp_filter *f =
400 READ_ONCE(current->seccomp.filter);
402 /* Ensure unexpected behavior doesn't result in failing open. */
403 if (WARN_ON(f == NULL))
404 return SECCOMP_RET_KILL_PROCESS;
406 if (seccomp_cache_check_allow(f, sd))
407 return SECCOMP_RET_ALLOW;
410 * All filters in the list are evaluated and the lowest BPF return
411 * value always takes priority (ignoring the DATA).
413 for (; f; f = f->prev) {
414 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
416 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
423 #endif /* CONFIG_SECCOMP_FILTER */
425 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
427 assert_spin_locked(¤t->sighand->siglock);
429 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
435 void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
437 static inline void seccomp_assign_mode(struct task_struct *task,
438 unsigned long seccomp_mode,
441 assert_spin_locked(&task->sighand->siglock);
443 task->seccomp.mode = seccomp_mode;
445 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
448 smp_mb__before_atomic();
449 /* Assume default seccomp processes want spec flaw mitigation. */
450 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
451 arch_seccomp_spec_mitigate(task);
452 set_task_syscall_work(task, SECCOMP);
455 #ifdef CONFIG_SECCOMP_FILTER
456 /* Returns 1 if the parent is an ancestor of the child. */
457 static int is_ancestor(struct seccomp_filter *parent,
458 struct seccomp_filter *child)
460 /* NULL is the root ancestor. */
463 for (; child; child = child->prev)
470 * seccomp_can_sync_threads: checks if all threads can be synchronized
472 * Expects sighand and cred_guard_mutex locks to be held.
474 * Returns 0 on success, -ve on error, or the pid of a thread which was
475 * either not in the correct seccomp mode or did not have an ancestral
478 static inline pid_t seccomp_can_sync_threads(void)
480 struct task_struct *thread, *caller;
482 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
483 assert_spin_locked(¤t->sighand->siglock);
485 /* Validate all threads being eligible for synchronization. */
487 for_each_thread(caller, thread) {
490 /* Skip current, since it is initiating the sync. */
491 if (thread == caller)
494 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
495 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
496 is_ancestor(thread->seccomp.filter,
497 caller->seccomp.filter)))
500 /* Return the first thread that cannot be synchronized. */
501 failed = task_pid_vnr(thread);
502 /* If the pid cannot be resolved, then return -ESRCH */
503 if (WARN_ON(failed == 0))
511 static inline void seccomp_filter_free(struct seccomp_filter *filter)
514 bpf_prog_destroy(filter->prog);
519 static void __seccomp_filter_orphan(struct seccomp_filter *orig)
521 while (orig && refcount_dec_and_test(&orig->users)) {
522 if (waitqueue_active(&orig->wqh))
523 wake_up_poll(&orig->wqh, EPOLLHUP);
528 static void __put_seccomp_filter(struct seccomp_filter *orig)
530 /* Clean up single-reference branches iteratively. */
531 while (orig && refcount_dec_and_test(&orig->refs)) {
532 struct seccomp_filter *freeme = orig;
534 seccomp_filter_free(freeme);
538 static void __seccomp_filter_release(struct seccomp_filter *orig)
540 /* Notify about any unused filters in the task's former filter tree. */
541 __seccomp_filter_orphan(orig);
542 /* Finally drop all references to the task's former tree. */
543 __put_seccomp_filter(orig);
547 * seccomp_filter_release - Detach the task from its filter tree,
548 * drop its reference count, and notify
549 * about unused filters
551 * This function should only be called when the task is exiting as
552 * it detaches it from its filter tree. As such, READ_ONCE() and
553 * barriers are not needed here, as would normally be needed.
555 void seccomp_filter_release(struct task_struct *tsk)
557 struct seccomp_filter *orig = tsk->seccomp.filter;
559 /* We are effectively holding the siglock by not having any sighand. */
560 WARN_ON(tsk->sighand != NULL);
562 /* Detach task from its filter tree. */
563 tsk->seccomp.filter = NULL;
564 __seccomp_filter_release(orig);
568 * seccomp_sync_threads: sets all threads to use current's filter
570 * Expects sighand and cred_guard_mutex locks to be held, and for
571 * seccomp_can_sync_threads() to have returned success already
572 * without dropping the locks.
575 static inline void seccomp_sync_threads(unsigned long flags)
577 struct task_struct *thread, *caller;
579 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
580 assert_spin_locked(¤t->sighand->siglock);
582 /* Synchronize all threads. */
584 for_each_thread(caller, thread) {
585 /* Skip current, since it needs no changes. */
586 if (thread == caller)
589 /* Get a task reference for the new leaf node. */
590 get_seccomp_filter(caller);
593 * Drop the task reference to the shared ancestor since
594 * current's path will hold a reference. (This also
595 * allows a put before the assignment.)
597 __seccomp_filter_release(thread->seccomp.filter);
599 /* Make our new filter tree visible. */
600 smp_store_release(&thread->seccomp.filter,
601 caller->seccomp.filter);
602 atomic_set(&thread->seccomp.filter_count,
603 atomic_read(&thread->seccomp.filter_count));
606 * Don't let an unprivileged task work around
607 * the no_new_privs restriction by creating
608 * a thread that sets it up, enters seccomp,
611 if (task_no_new_privs(caller))
612 task_set_no_new_privs(thread);
615 * Opt the other thread into seccomp if needed.
616 * As threads are considered to be trust-realm
617 * equivalent (see ptrace_may_access), it is safe to
618 * allow one thread to transition the other.
620 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
621 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
627 * seccomp_prepare_filter: Prepares a seccomp filter for use.
628 * @fprog: BPF program to install
630 * Returns filter on success or an ERR_PTR on failure.
632 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
634 struct seccomp_filter *sfilter;
636 const bool save_orig =
637 #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
643 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
644 return ERR_PTR(-EINVAL);
646 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
649 * Installing a seccomp filter requires that the task has
650 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
651 * This avoids scenarios where unprivileged tasks can affect the
652 * behavior of privileged children.
654 if (!task_no_new_privs(current) &&
655 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
656 return ERR_PTR(-EACCES);
658 /* Allocate a new seccomp_filter */
659 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
661 return ERR_PTR(-ENOMEM);
663 mutex_init(&sfilter->notify_lock);
664 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
665 seccomp_check_filter, save_orig);
671 refcount_set(&sfilter->refs, 1);
672 refcount_set(&sfilter->users, 1);
673 init_waitqueue_head(&sfilter->wqh);
679 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
680 * @user_filter: pointer to the user data containing a sock_fprog.
682 * Returns 0 on success and non-zero otherwise.
684 static struct seccomp_filter *
685 seccomp_prepare_user_filter(const char __user *user_filter)
687 struct sock_fprog fprog;
688 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
691 if (in_compat_syscall()) {
692 struct compat_sock_fprog fprog32;
693 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
695 fprog.len = fprog32.len;
696 fprog.filter = compat_ptr(fprog32.filter);
697 } else /* falls through to the if below. */
699 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
701 filter = seccomp_prepare_filter(&fprog);
706 #ifdef SECCOMP_ARCH_NATIVE
708 * seccomp_is_const_allow - check if filter is constant allow with given data
709 * @fprog: The BPF programs
710 * @sd: The seccomp data to check against, only syscall number and arch
711 * number are considered constant.
713 static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
714 struct seccomp_data *sd)
716 unsigned int reg_value = 0;
720 if (WARN_ON_ONCE(!fprog))
723 for (pc = 0; pc < fprog->len; pc++) {
724 struct sock_filter *insn = &fprog->filter[pc];
725 u16 code = insn->code;
729 case BPF_LD | BPF_W | BPF_ABS:
731 case offsetof(struct seccomp_data, nr):
734 case offsetof(struct seccomp_data, arch):
735 reg_value = sd->arch;
738 /* can't optimize (non-constant value load) */
742 case BPF_RET | BPF_K:
743 /* reached return with constant values only, check allow */
744 return k == SECCOMP_RET_ALLOW;
745 case BPF_JMP | BPF_JA:
748 case BPF_JMP | BPF_JEQ | BPF_K:
749 case BPF_JMP | BPF_JGE | BPF_K:
750 case BPF_JMP | BPF_JGT | BPF_K:
751 case BPF_JMP | BPF_JSET | BPF_K:
752 switch (BPF_OP(code)) {
754 op_res = reg_value == k;
757 op_res = reg_value >= k;
760 op_res = reg_value > k;
763 op_res = !!(reg_value & k);
766 /* can't optimize (unknown jump) */
770 pc += op_res ? insn->jt : insn->jf;
772 case BPF_ALU | BPF_AND | BPF_K:
776 /* can't optimize (unknown insn) */
781 /* ran off the end of the filter?! */
786 static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
787 void *bitmap, const void *bitmap_prev,
788 size_t bitmap_size, int arch)
790 struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
791 struct seccomp_data sd;
795 /* The new filter must be as restrictive as the last. */
796 bitmap_copy(bitmap, bitmap_prev, bitmap_size);
798 /* Before any filters, all syscalls are always allowed. */
799 bitmap_fill(bitmap, bitmap_size);
802 for (nr = 0; nr < bitmap_size; nr++) {
803 /* No bitmap change: not a cacheable action. */
804 if (!test_bit(nr, bitmap))
810 /* No bitmap change: continue to always allow. */
811 if (seccomp_is_const_allow(fprog, &sd))
815 * Not a cacheable action: always run filters.
816 * atomic clear_bit() not needed, filter not visible yet.
818 __clear_bit(nr, bitmap);
823 * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
824 * @sfilter: The seccomp filter
826 * Returns 0 if successful or -errno if error occurred.
828 static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
830 struct action_cache *cache = &sfilter->cache;
831 const struct action_cache *cache_prev =
832 sfilter->prev ? &sfilter->prev->cache : NULL;
834 seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
835 cache_prev ? cache_prev->allow_native : NULL,
836 SECCOMP_ARCH_NATIVE_NR,
837 SECCOMP_ARCH_NATIVE);
839 #ifdef SECCOMP_ARCH_COMPAT
840 seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
841 cache_prev ? cache_prev->allow_compat : NULL,
842 SECCOMP_ARCH_COMPAT_NR,
843 SECCOMP_ARCH_COMPAT);
844 #endif /* SECCOMP_ARCH_COMPAT */
846 #endif /* SECCOMP_ARCH_NATIVE */
849 * seccomp_attach_filter: validate and attach filter
850 * @flags: flags to change filter behavior
851 * @filter: seccomp filter to add to the current process
853 * Caller must be holding current->sighand->siglock lock.
855 * Returns 0 on success, -ve on error, or
856 * - in TSYNC mode: the pid of a thread which was either not in the correct
857 * seccomp mode or did not have an ancestral seccomp filter
858 * - in NEW_LISTENER mode: the fd of the new listener
860 static long seccomp_attach_filter(unsigned int flags,
861 struct seccomp_filter *filter)
863 unsigned long total_insns;
864 struct seccomp_filter *walker;
866 assert_spin_locked(¤t->sighand->siglock);
868 /* Validate resulting filter length. */
869 total_insns = filter->prog->len;
870 for (walker = current->seccomp.filter; walker; walker = walker->prev)
871 total_insns += walker->prog->len + 4; /* 4 instr penalty */
872 if (total_insns > MAX_INSNS_PER_PATH)
875 /* If thread sync has been requested, check that it is possible. */
876 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
879 ret = seccomp_can_sync_threads();
881 if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
888 /* Set log flag, if present. */
889 if (flags & SECCOMP_FILTER_FLAG_LOG)
893 * If there is an existing filter, make it the prev and don't drop its
896 filter->prev = current->seccomp.filter;
897 seccomp_cache_prepare(filter);
898 current->seccomp.filter = filter;
899 atomic_inc(¤t->seccomp.filter_count);
901 /* Now that the new filter is in place, synchronize to all threads. */
902 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
903 seccomp_sync_threads(flags);
908 static void __get_seccomp_filter(struct seccomp_filter *filter)
910 refcount_inc(&filter->refs);
913 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
914 void get_seccomp_filter(struct task_struct *tsk)
916 struct seccomp_filter *orig = tsk->seccomp.filter;
919 __get_seccomp_filter(orig);
920 refcount_inc(&orig->users);
923 static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
926 info->si_signo = SIGSYS;
927 info->si_code = SYS_SECCOMP;
928 info->si_call_addr = (void __user *)KSTK_EIP(current);
929 info->si_errno = reason;
930 info->si_arch = syscall_get_arch(current);
931 info->si_syscall = syscall;
935 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
936 * @syscall: syscall number to send to userland
937 * @reason: filter-supplied reason code to send to userland (via si_errno)
939 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
941 static void seccomp_send_sigsys(int syscall, int reason)
943 struct kernel_siginfo info;
944 seccomp_init_siginfo(&info, syscall, reason);
945 force_sig_info(&info);
947 #endif /* CONFIG_SECCOMP_FILTER */
949 /* For use with seccomp_actions_logged */
950 #define SECCOMP_LOG_KILL_PROCESS (1 << 0)
951 #define SECCOMP_LOG_KILL_THREAD (1 << 1)
952 #define SECCOMP_LOG_TRAP (1 << 2)
953 #define SECCOMP_LOG_ERRNO (1 << 3)
954 #define SECCOMP_LOG_TRACE (1 << 4)
955 #define SECCOMP_LOG_LOG (1 << 5)
956 #define SECCOMP_LOG_ALLOW (1 << 6)
957 #define SECCOMP_LOG_USER_NOTIF (1 << 7)
959 static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
960 SECCOMP_LOG_KILL_THREAD |
963 SECCOMP_LOG_USER_NOTIF |
967 static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
973 case SECCOMP_RET_ALLOW:
975 case SECCOMP_RET_TRAP:
976 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
978 case SECCOMP_RET_ERRNO:
979 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
981 case SECCOMP_RET_TRACE:
982 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
984 case SECCOMP_RET_USER_NOTIF:
985 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
987 case SECCOMP_RET_LOG:
988 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
990 case SECCOMP_RET_KILL_THREAD:
991 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
993 case SECCOMP_RET_KILL_PROCESS:
995 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
999 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
1000 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
1001 * any action from being logged by removing the action name from the
1002 * seccomp_actions_logged sysctl.
1007 audit_seccomp(syscall, signr, action);
1011 * Secure computing mode 1 allows only read/write/exit/sigreturn.
1012 * To be fully secure this must be combined with rlimit
1013 * to limit the stack allocations too.
1015 static const int mode1_syscalls[] = {
1016 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
1017 -1, /* negative terminated */
1020 static void __secure_computing_strict(int this_syscall)
1022 const int *allowed_syscalls = mode1_syscalls;
1023 #ifdef CONFIG_COMPAT
1024 if (in_compat_syscall())
1025 allowed_syscalls = get_compat_mode1_syscalls();
1028 if (*allowed_syscalls == this_syscall)
1030 } while (*++allowed_syscalls != -1);
1032 #ifdef SECCOMP_DEBUG
1035 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1039 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1040 void secure_computing_strict(int this_syscall)
1042 int mode = current->seccomp.mode;
1044 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1045 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1048 if (mode == SECCOMP_MODE_DISABLED)
1050 else if (mode == SECCOMP_MODE_STRICT)
1051 __secure_computing_strict(this_syscall);
1057 #ifdef CONFIG_SECCOMP_FILTER
1058 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1061 * Note: overflow is ok here, the id just needs to be unique per
1064 lockdep_assert_held(&filter->notify_lock);
1065 return filter->notif->next_id++;
1068 static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd)
1071 * Remove the notification, and reset the list pointers, indicating
1072 * that it has been handled.
1074 list_del_init(&addfd->list);
1076 addfd->ret = receive_fd(addfd->file, addfd->flags);
1078 addfd->ret = receive_fd_replace(addfd->fd, addfd->file,
1080 complete(&addfd->completion);
1083 static int seccomp_do_user_notification(int this_syscall,
1084 struct seccomp_filter *match,
1085 const struct seccomp_data *sd)
1090 struct seccomp_knotif n = {};
1091 struct seccomp_kaddfd *addfd, *tmp;
1093 mutex_lock(&match->notify_lock);
1099 n.state = SECCOMP_NOTIFY_INIT;
1101 n.id = seccomp_next_notify_id(match);
1102 init_completion(&n.ready);
1103 list_add(&n.list, &match->notif->notifications);
1104 INIT_LIST_HEAD(&n.addfd);
1106 up(&match->notif->request);
1107 wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
1110 * This is where we wait for a reply from userspace.
1113 mutex_unlock(&match->notify_lock);
1114 err = wait_for_completion_interruptible(&n.ready);
1115 mutex_lock(&match->notify_lock);
1119 addfd = list_first_entry_or_null(&n.addfd,
1120 struct seccomp_kaddfd, list);
1121 /* Check if we were woken up by a addfd message */
1123 seccomp_handle_addfd(addfd);
1125 } while (n.state != SECCOMP_NOTIFY_REPLIED);
1132 /* If there were any pending addfd calls, clear them out */
1133 list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1134 /* The process went away before we got a chance to handle it */
1135 addfd->ret = -ESRCH;
1136 list_del_init(&addfd->list);
1137 complete(&addfd->completion);
1141 * Note that it's possible the listener died in between the time when
1142 * we were notified of a response (or a signal) and when we were able to
1143 * re-acquire the lock, so only delete from the list if the
1144 * notification actually exists.
1146 * Also note that this test is only valid because there's no way to
1147 * *reattach* to a notifier right now. If one is added, we'll need to
1148 * keep track of the notif itself and make sure they match here.
1153 mutex_unlock(&match->notify_lock);
1155 /* Userspace requests to continue the syscall. */
1156 if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1159 syscall_set_return_value(current, current_pt_regs(),
1164 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1165 const bool recheck_after_trace)
1167 u32 filter_ret, action;
1168 struct seccomp_filter *match = NULL;
1170 struct seccomp_data sd_local;
1173 * Make sure that any changes to mode from another thread have
1174 * been seen after SYSCALL_WORK_SECCOMP was seen.
1179 populate_seccomp_data(&sd_local);
1183 filter_ret = seccomp_run_filters(sd, &match);
1184 data = filter_ret & SECCOMP_RET_DATA;
1185 action = filter_ret & SECCOMP_RET_ACTION_FULL;
1188 case SECCOMP_RET_ERRNO:
1189 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1190 if (data > MAX_ERRNO)
1192 syscall_set_return_value(current, current_pt_regs(),
1196 case SECCOMP_RET_TRAP:
1197 /* Show the handler the original registers. */
1198 syscall_rollback(current, current_pt_regs());
1199 /* Let the filter pass back 16 bits of data. */
1200 seccomp_send_sigsys(this_syscall, data);
1203 case SECCOMP_RET_TRACE:
1204 /* We've been put in this state by the ptracer already. */
1205 if (recheck_after_trace)
1208 /* ENOSYS these calls if there is no tracer attached. */
1209 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1210 syscall_set_return_value(current,
1216 /* Allow the BPF to provide the event message */
1217 ptrace_event(PTRACE_EVENT_SECCOMP, data);
1219 * The delivery of a fatal signal during event
1220 * notification may silently skip tracer notification,
1221 * which could leave us with a potentially unmodified
1222 * syscall that the tracer would have liked to have
1223 * changed. Since the process is about to die, we just
1224 * force the syscall to be skipped and let the signal
1225 * kill the process and correctly handle any tracer exit
1228 if (fatal_signal_pending(current))
1230 /* Check if the tracer forced the syscall to be skipped. */
1231 this_syscall = syscall_get_nr(current, current_pt_regs());
1232 if (this_syscall < 0)
1236 * Recheck the syscall, since it may have changed. This
1237 * intentionally uses a NULL struct seccomp_data to force
1238 * a reload of all registers. This does not goto skip since
1239 * a skip would have already been reported.
1241 if (__seccomp_filter(this_syscall, NULL, true))
1246 case SECCOMP_RET_USER_NOTIF:
1247 if (seccomp_do_user_notification(this_syscall, match, sd))
1252 case SECCOMP_RET_LOG:
1253 seccomp_log(this_syscall, 0, action, true);
1256 case SECCOMP_RET_ALLOW:
1258 * Note that the "match" filter will always be NULL for
1259 * this action since SECCOMP_RET_ALLOW is the starting
1260 * state in seccomp_run_filters().
1264 case SECCOMP_RET_KILL_THREAD:
1265 case SECCOMP_RET_KILL_PROCESS:
1267 seccomp_log(this_syscall, SIGSYS, action, true);
1268 /* Dump core only if this is the last remaining thread. */
1269 if (action != SECCOMP_RET_KILL_THREAD ||
1270 get_nr_threads(current) == 1) {
1271 kernel_siginfo_t info;
1273 /* Show the original registers in the dump. */
1274 syscall_rollback(current, current_pt_regs());
1275 /* Trigger a manual coredump since do_exit skips it. */
1276 seccomp_init_siginfo(&info, this_syscall, data);
1279 if (action == SECCOMP_RET_KILL_THREAD)
1282 do_group_exit(SIGSYS);
1288 seccomp_log(this_syscall, 0, action, match ? match->log : false);
1292 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1293 const bool recheck_after_trace)
1301 int __secure_computing(const struct seccomp_data *sd)
1303 int mode = current->seccomp.mode;
1306 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1307 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1310 this_syscall = sd ? sd->nr :
1311 syscall_get_nr(current, current_pt_regs());
1314 case SECCOMP_MODE_STRICT:
1315 __secure_computing_strict(this_syscall); /* may call do_exit */
1317 case SECCOMP_MODE_FILTER:
1318 return __seccomp_filter(this_syscall, sd, false);
1323 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1325 long prctl_get_seccomp(void)
1327 return current->seccomp.mode;
1331 * seccomp_set_mode_strict: internal function for setting strict seccomp
1333 * Once current->seccomp.mode is non-zero, it may not be changed.
1335 * Returns 0 on success or -EINVAL on failure.
1337 static long seccomp_set_mode_strict(void)
1339 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1342 spin_lock_irq(¤t->sighand->siglock);
1344 if (!seccomp_may_assign_mode(seccomp_mode))
1350 seccomp_assign_mode(current, seccomp_mode, 0);
1354 spin_unlock_irq(¤t->sighand->siglock);
1359 #ifdef CONFIG_SECCOMP_FILTER
1360 static void seccomp_notify_free(struct seccomp_filter *filter)
1362 kfree(filter->notif);
1363 filter->notif = NULL;
1366 static void seccomp_notify_detach(struct seccomp_filter *filter)
1368 struct seccomp_knotif *knotif;
1373 mutex_lock(&filter->notify_lock);
1376 * If this file is being closed because e.g. the task who owned it
1377 * died, let's wake everyone up who was waiting on us.
1379 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1380 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1383 knotif->state = SECCOMP_NOTIFY_REPLIED;
1384 knotif->error = -ENOSYS;
1388 * We do not need to wake up any pending addfd messages, as
1389 * the notifier will do that for us, as this just looks
1390 * like a standard reply.
1392 complete(&knotif->ready);
1395 seccomp_notify_free(filter);
1396 mutex_unlock(&filter->notify_lock);
1399 static int seccomp_notify_release(struct inode *inode, struct file *file)
1401 struct seccomp_filter *filter = file->private_data;
1403 seccomp_notify_detach(filter);
1404 __put_seccomp_filter(filter);
1408 /* must be called with notif_lock held */
1409 static inline struct seccomp_knotif *
1410 find_notification(struct seccomp_filter *filter, u64 id)
1412 struct seccomp_knotif *cur;
1414 lockdep_assert_held(&filter->notify_lock);
1416 list_for_each_entry(cur, &filter->notif->notifications, list) {
1425 static long seccomp_notify_recv(struct seccomp_filter *filter,
1428 struct seccomp_knotif *knotif = NULL, *cur;
1429 struct seccomp_notif unotif;
1432 /* Verify that we're not given garbage to keep struct extensible. */
1433 ret = check_zeroed_user(buf, sizeof(unotif));
1439 memset(&unotif, 0, sizeof(unotif));
1441 ret = down_interruptible(&filter->notif->request);
1445 mutex_lock(&filter->notify_lock);
1446 list_for_each_entry(cur, &filter->notif->notifications, list) {
1447 if (cur->state == SECCOMP_NOTIFY_INIT) {
1454 * If we didn't find a notification, it could be that the task was
1455 * interrupted by a fatal signal between the time we were woken and
1456 * when we were able to acquire the rw lock.
1463 unotif.id = knotif->id;
1464 unotif.pid = task_pid_vnr(knotif->task);
1465 unotif.data = *(knotif->data);
1467 knotif->state = SECCOMP_NOTIFY_SENT;
1468 wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1471 mutex_unlock(&filter->notify_lock);
1473 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1477 * Userspace screwed up. To make sure that we keep this
1478 * notification alive, let's reset it back to INIT. It
1479 * may have died when we released the lock, so we need to make
1480 * sure it's still around.
1482 mutex_lock(&filter->notify_lock);
1483 knotif = find_notification(filter, unotif.id);
1485 knotif->state = SECCOMP_NOTIFY_INIT;
1486 up(&filter->notif->request);
1488 mutex_unlock(&filter->notify_lock);
1494 static long seccomp_notify_send(struct seccomp_filter *filter,
1497 struct seccomp_notif_resp resp = {};
1498 struct seccomp_knotif *knotif;
1501 if (copy_from_user(&resp, buf, sizeof(resp)))
1504 if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1507 if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1508 (resp.error || resp.val))
1511 ret = mutex_lock_interruptible(&filter->notify_lock);
1515 knotif = find_notification(filter, resp.id);
1521 /* Allow exactly one reply. */
1522 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1528 knotif->state = SECCOMP_NOTIFY_REPLIED;
1529 knotif->error = resp.error;
1530 knotif->val = resp.val;
1531 knotif->flags = resp.flags;
1532 complete(&knotif->ready);
1534 mutex_unlock(&filter->notify_lock);
1538 static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1541 struct seccomp_knotif *knotif;
1545 if (copy_from_user(&id, buf, sizeof(id)))
1548 ret = mutex_lock_interruptible(&filter->notify_lock);
1552 knotif = find_notification(filter, id);
1553 if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1558 mutex_unlock(&filter->notify_lock);
1562 static long seccomp_notify_addfd(struct seccomp_filter *filter,
1563 struct seccomp_notif_addfd __user *uaddfd,
1566 struct seccomp_notif_addfd addfd;
1567 struct seccomp_knotif *knotif;
1568 struct seccomp_kaddfd kaddfd;
1571 BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1572 BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1574 if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1577 ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1581 if (addfd.newfd_flags & ~O_CLOEXEC)
1584 if (addfd.flags & ~SECCOMP_ADDFD_FLAG_SETFD)
1587 if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1590 kaddfd.file = fget(addfd.srcfd);
1594 kaddfd.flags = addfd.newfd_flags;
1595 kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1596 kaddfd.fd = addfd.newfd;
1597 init_completion(&kaddfd.completion);
1599 ret = mutex_lock_interruptible(&filter->notify_lock);
1603 knotif = find_notification(filter, addfd.id);
1610 * We do not want to allow for FD injection to occur before the
1611 * notification has been picked up by a userspace handler, or after
1612 * the notification has been replied to.
1614 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1619 list_add(&kaddfd.list, &knotif->addfd);
1620 complete(&knotif->ready);
1621 mutex_unlock(&filter->notify_lock);
1623 /* Now we wait for it to be processed or be interrupted */
1624 ret = wait_for_completion_interruptible(&kaddfd.completion);
1627 * We had a successful completion. The other side has already
1628 * removed us from the addfd queue, and
1629 * wait_for_completion_interruptible has a memory barrier upon
1630 * success that lets us read this value directly without
1637 mutex_lock(&filter->notify_lock);
1639 * Even though we were woken up by a signal and not a successful
1640 * completion, a completion may have happened in the mean time.
1642 * We need to check again if the addfd request has been handled,
1643 * and if not, we will remove it from the queue.
1645 if (list_empty(&kaddfd.list))
1648 list_del(&kaddfd.list);
1651 mutex_unlock(&filter->notify_lock);
1658 static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1661 struct seccomp_filter *filter = file->private_data;
1662 void __user *buf = (void __user *)arg;
1664 /* Fixed-size ioctls */
1666 case SECCOMP_IOCTL_NOTIF_RECV:
1667 return seccomp_notify_recv(filter, buf);
1668 case SECCOMP_IOCTL_NOTIF_SEND:
1669 return seccomp_notify_send(filter, buf);
1670 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1671 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1672 return seccomp_notify_id_valid(filter, buf);
1675 /* Extensible Argument ioctls */
1676 #define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1677 switch (EA_IOCTL(cmd)) {
1678 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1679 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1685 static __poll_t seccomp_notify_poll(struct file *file,
1686 struct poll_table_struct *poll_tab)
1688 struct seccomp_filter *filter = file->private_data;
1690 struct seccomp_knotif *cur;
1692 poll_wait(file, &filter->wqh, poll_tab);
1694 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1697 list_for_each_entry(cur, &filter->notif->notifications, list) {
1698 if (cur->state == SECCOMP_NOTIFY_INIT)
1699 ret |= EPOLLIN | EPOLLRDNORM;
1700 if (cur->state == SECCOMP_NOTIFY_SENT)
1701 ret |= EPOLLOUT | EPOLLWRNORM;
1702 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1706 mutex_unlock(&filter->notify_lock);
1708 if (refcount_read(&filter->users) == 0)
1714 static const struct file_operations seccomp_notify_ops = {
1715 .poll = seccomp_notify_poll,
1716 .release = seccomp_notify_release,
1717 .unlocked_ioctl = seccomp_notify_ioctl,
1718 .compat_ioctl = seccomp_notify_ioctl,
1721 static struct file *init_listener(struct seccomp_filter *filter)
1725 ret = ERR_PTR(-ENOMEM);
1726 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1730 sema_init(&filter->notif->request, 0);
1731 filter->notif->next_id = get_random_u64();
1732 INIT_LIST_HEAD(&filter->notif->notifications);
1734 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1739 /* The file has a reference to it now */
1740 __get_seccomp_filter(filter);
1744 seccomp_notify_free(filter);
1750 * Does @new_child have a listener while an ancestor also has a listener?
1751 * If so, we'll want to reject this filter.
1752 * This only has to be tested for the current process, even in the TSYNC case,
1753 * because TSYNC installs @child with the same parent on all threads.
1754 * Note that @new_child is not hooked up to its parent at this point yet, so
1755 * we use current->seccomp.filter.
1757 static bool has_duplicate_listener(struct seccomp_filter *new_child)
1759 struct seccomp_filter *cur;
1761 /* must be protected against concurrent TSYNC */
1762 lockdep_assert_held(¤t->sighand->siglock);
1764 if (!new_child->notif)
1766 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1775 * seccomp_set_mode_filter: internal function for setting seccomp filter
1776 * @flags: flags to change filter behavior
1777 * @filter: struct sock_fprog containing filter
1779 * This function may be called repeatedly to install additional filters.
1780 * Every filter successfully installed will be evaluated (in reverse order)
1781 * for each system call the task makes.
1783 * Once current->seccomp.mode is non-zero, it may not be changed.
1785 * Returns 0 on success or -EINVAL on failure.
1787 static long seccomp_set_mode_filter(unsigned int flags,
1788 const char __user *filter)
1790 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1791 struct seccomp_filter *prepared = NULL;
1794 struct file *listener_f = NULL;
1796 /* Validate flags. */
1797 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1801 * In the successful case, NEW_LISTENER returns the new listener fd.
1802 * But in the failure case, TSYNC returns the thread that died. If you
1803 * combine these two flags, there's no way to tell whether something
1804 * succeeded or failed. So, let's disallow this combination if the user
1805 * has not explicitly requested no errors from TSYNC.
1807 if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1808 (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1809 ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1812 /* Prepare the new filter before holding any locks. */
1813 prepared = seccomp_prepare_user_filter(filter);
1814 if (IS_ERR(prepared))
1815 return PTR_ERR(prepared);
1817 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1818 listener = get_unused_fd_flags(O_CLOEXEC);
1824 listener_f = init_listener(prepared);
1825 if (IS_ERR(listener_f)) {
1826 put_unused_fd(listener);
1827 ret = PTR_ERR(listener_f);
1833 * Make sure we cannot change seccomp or nnp state via TSYNC
1834 * while another thread is in the middle of calling exec.
1836 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1837 mutex_lock_killable(¤t->signal->cred_guard_mutex))
1840 spin_lock_irq(¤t->sighand->siglock);
1842 if (!seccomp_may_assign_mode(seccomp_mode))
1845 if (has_duplicate_listener(prepared)) {
1850 ret = seccomp_attach_filter(flags, prepared);
1853 /* Do not free the successfully attached filter. */
1856 seccomp_assign_mode(current, seccomp_mode, flags);
1858 spin_unlock_irq(¤t->sighand->siglock);
1859 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1860 mutex_unlock(¤t->signal->cred_guard_mutex);
1862 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1864 listener_f->private_data = NULL;
1866 put_unused_fd(listener);
1867 seccomp_notify_detach(prepared);
1869 fd_install(listener, listener_f);
1874 seccomp_filter_free(prepared);
1878 static inline long seccomp_set_mode_filter(unsigned int flags,
1879 const char __user *filter)
1885 static long seccomp_get_action_avail(const char __user *uaction)
1889 if (copy_from_user(&action, uaction, sizeof(action)))
1893 case SECCOMP_RET_KILL_PROCESS:
1894 case SECCOMP_RET_KILL_THREAD:
1895 case SECCOMP_RET_TRAP:
1896 case SECCOMP_RET_ERRNO:
1897 case SECCOMP_RET_USER_NOTIF:
1898 case SECCOMP_RET_TRACE:
1899 case SECCOMP_RET_LOG:
1900 case SECCOMP_RET_ALLOW:
1909 static long seccomp_get_notif_sizes(void __user *usizes)
1911 struct seccomp_notif_sizes sizes = {
1912 .seccomp_notif = sizeof(struct seccomp_notif),
1913 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1914 .seccomp_data = sizeof(struct seccomp_data),
1917 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1923 /* Common entry point for both prctl and syscall. */
1924 static long do_seccomp(unsigned int op, unsigned int flags,
1928 case SECCOMP_SET_MODE_STRICT:
1929 if (flags != 0 || uargs != NULL)
1931 return seccomp_set_mode_strict();
1932 case SECCOMP_SET_MODE_FILTER:
1933 return seccomp_set_mode_filter(flags, uargs);
1934 case SECCOMP_GET_ACTION_AVAIL:
1938 return seccomp_get_action_avail(uargs);
1939 case SECCOMP_GET_NOTIF_SIZES:
1943 return seccomp_get_notif_sizes(uargs);
1949 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1950 void __user *, uargs)
1952 return do_seccomp(op, flags, uargs);
1956 * prctl_set_seccomp: configures current->seccomp.mode
1957 * @seccomp_mode: requested mode to use
1958 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1960 * Returns 0 on success or -EINVAL on failure.
1962 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
1967 switch (seccomp_mode) {
1968 case SECCOMP_MODE_STRICT:
1969 op = SECCOMP_SET_MODE_STRICT;
1971 * Setting strict mode through prctl always ignored filter,
1972 * so make sure it is always NULL here to pass the internal
1973 * check in do_seccomp().
1977 case SECCOMP_MODE_FILTER:
1978 op = SECCOMP_SET_MODE_FILTER;
1985 /* prctl interface doesn't have flags, so they are always zero. */
1986 return do_seccomp(op, 0, uargs);
1989 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1990 static struct seccomp_filter *get_nth_filter(struct task_struct *task,
1991 unsigned long filter_off)
1993 struct seccomp_filter *orig, *filter;
1994 unsigned long count;
1997 * Note: this is only correct because the caller should be the (ptrace)
1998 * tracer of the task, otherwise lock_task_sighand is needed.
2000 spin_lock_irq(&task->sighand->siglock);
2002 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2003 spin_unlock_irq(&task->sighand->siglock);
2004 return ERR_PTR(-EINVAL);
2007 orig = task->seccomp.filter;
2008 __get_seccomp_filter(orig);
2009 spin_unlock_irq(&task->sighand->siglock);
2012 for (filter = orig; filter; filter = filter->prev)
2015 if (filter_off >= count) {
2016 filter = ERR_PTR(-ENOENT);
2020 count -= filter_off;
2021 for (filter = orig; filter && count > 1; filter = filter->prev)
2024 if (WARN_ON(count != 1 || !filter)) {
2025 filter = ERR_PTR(-ENOENT);
2029 __get_seccomp_filter(filter);
2032 __put_seccomp_filter(orig);
2036 long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2039 struct seccomp_filter *filter;
2040 struct sock_fprog_kern *fprog;
2043 if (!capable(CAP_SYS_ADMIN) ||
2044 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2048 filter = get_nth_filter(task, filter_off);
2050 return PTR_ERR(filter);
2052 fprog = filter->prog->orig_prog;
2054 /* This must be a new non-cBPF filter, since we save
2055 * every cBPF filter's orig_prog above when
2056 * CONFIG_CHECKPOINT_RESTORE is enabled.
2066 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2070 __put_seccomp_filter(filter);
2074 long seccomp_get_metadata(struct task_struct *task,
2075 unsigned long size, void __user *data)
2078 struct seccomp_filter *filter;
2079 struct seccomp_metadata kmd = {};
2081 if (!capable(CAP_SYS_ADMIN) ||
2082 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2086 size = min_t(unsigned long, size, sizeof(kmd));
2088 if (size < sizeof(kmd.filter_off))
2091 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2094 filter = get_nth_filter(task, kmd.filter_off);
2096 return PTR_ERR(filter);
2099 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2102 if (copy_to_user(data, &kmd, size))
2105 __put_seccomp_filter(filter);
2110 #ifdef CONFIG_SYSCTL
2112 /* Human readable action names for friendly sysctl interaction */
2113 #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
2114 #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
2115 #define SECCOMP_RET_TRAP_NAME "trap"
2116 #define SECCOMP_RET_ERRNO_NAME "errno"
2117 #define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
2118 #define SECCOMP_RET_TRACE_NAME "trace"
2119 #define SECCOMP_RET_LOG_NAME "log"
2120 #define SECCOMP_RET_ALLOW_NAME "allow"
2122 static const char seccomp_actions_avail[] =
2123 SECCOMP_RET_KILL_PROCESS_NAME " "
2124 SECCOMP_RET_KILL_THREAD_NAME " "
2125 SECCOMP_RET_TRAP_NAME " "
2126 SECCOMP_RET_ERRNO_NAME " "
2127 SECCOMP_RET_USER_NOTIF_NAME " "
2128 SECCOMP_RET_TRACE_NAME " "
2129 SECCOMP_RET_LOG_NAME " "
2130 SECCOMP_RET_ALLOW_NAME;
2132 struct seccomp_log_name {
2137 static const struct seccomp_log_name seccomp_log_names[] = {
2138 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2139 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2140 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2141 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2142 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2143 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2144 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2145 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2149 static bool seccomp_names_from_actions_logged(char *names, size_t size,
2153 const struct seccomp_log_name *cur;
2154 bool append_sep = false;
2156 for (cur = seccomp_log_names; cur->name && size; cur++) {
2159 if (!(actions_logged & cur->log))
2163 ret = strscpy(names, sep, size);
2172 ret = strscpy(names, cur->name, size);
2183 static bool seccomp_action_logged_from_name(u32 *action_logged,
2186 const struct seccomp_log_name *cur;
2188 for (cur = seccomp_log_names; cur->name; cur++) {
2189 if (!strcmp(cur->name, name)) {
2190 *action_logged = cur->log;
2198 static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2202 *actions_logged = 0;
2203 while ((name = strsep(&names, " ")) && *name) {
2204 u32 action_logged = 0;
2206 if (!seccomp_action_logged_from_name(&action_logged, name))
2209 *actions_logged |= action_logged;
2215 static int read_actions_logged(struct ctl_table *ro_table, void *buffer,
2216 size_t *lenp, loff_t *ppos)
2218 char names[sizeof(seccomp_actions_avail)];
2219 struct ctl_table table;
2221 memset(names, 0, sizeof(names));
2223 if (!seccomp_names_from_actions_logged(names, sizeof(names),
2224 seccomp_actions_logged, " "))
2229 table.maxlen = sizeof(names);
2230 return proc_dostring(&table, 0, buffer, lenp, ppos);
2233 static int write_actions_logged(struct ctl_table *ro_table, void *buffer,
2234 size_t *lenp, loff_t *ppos, u32 *actions_logged)
2236 char names[sizeof(seccomp_actions_avail)];
2237 struct ctl_table table;
2240 if (!capable(CAP_SYS_ADMIN))
2243 memset(names, 0, sizeof(names));
2247 table.maxlen = sizeof(names);
2248 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2252 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2255 if (*actions_logged & SECCOMP_LOG_ALLOW)
2258 seccomp_actions_logged = *actions_logged;
2262 static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2265 char names[sizeof(seccomp_actions_avail)];
2266 char old_names[sizeof(seccomp_actions_avail)];
2267 const char *new = names;
2268 const char *old = old_names;
2273 memset(names, 0, sizeof(names));
2274 memset(old_names, 0, sizeof(old_names));
2278 else if (!actions_logged)
2280 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2281 actions_logged, ","))
2284 if (!old_actions_logged)
2286 else if (!seccomp_names_from_actions_logged(old_names,
2288 old_actions_logged, ","))
2291 return audit_seccomp_actions_logged(new, old, !ret);
2294 static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
2295 void *buffer, size_t *lenp,
2301 u32 actions_logged = 0;
2302 u32 old_actions_logged = seccomp_actions_logged;
2304 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2306 audit_actions_logged(actions_logged, old_actions_logged, ret);
2308 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2313 static struct ctl_path seccomp_sysctl_path[] = {
2314 { .procname = "kernel", },
2315 { .procname = "seccomp", },
2319 static struct ctl_table seccomp_sysctl_table[] = {
2321 .procname = "actions_avail",
2322 .data = (void *) &seccomp_actions_avail,
2323 .maxlen = sizeof(seccomp_actions_avail),
2325 .proc_handler = proc_dostring,
2328 .procname = "actions_logged",
2330 .proc_handler = seccomp_actions_logged_handler,
2335 static int __init seccomp_sysctl_init(void)
2337 struct ctl_table_header *hdr;
2339 hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
2341 pr_warn("sysctl registration failed\n");
2343 kmemleak_not_leak(hdr);
2348 device_initcall(seccomp_sysctl_init)
2350 #endif /* CONFIG_SYSCTL */
2352 #ifdef CONFIG_SECCOMP_CACHE_DEBUG
2353 /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2354 static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2355 const void *bitmap, size_t bitmap_size)
2359 for (nr = 0; nr < bitmap_size; nr++) {
2360 bool cached = test_bit(nr, bitmap);
2361 char *status = cached ? "ALLOW" : "FILTER";
2363 seq_printf(m, "%s %d %s\n", name, nr, status);
2367 int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2368 struct pid *pid, struct task_struct *task)
2370 struct seccomp_filter *f;
2371 unsigned long flags;
2374 * We don't want some sandboxed process to know what their seccomp
2375 * filters consist of.
2377 if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2380 if (!lock_task_sighand(task, &flags))
2383 f = READ_ONCE(task->seccomp.filter);
2385 unlock_task_sighand(task, &flags);
2389 /* prevent filter from being freed while we are printing it */
2390 __get_seccomp_filter(f);
2391 unlock_task_sighand(task, &flags);
2393 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2394 f->cache.allow_native,
2395 SECCOMP_ARCH_NATIVE_NR);
2397 #ifdef SECCOMP_ARCH_COMPAT
2398 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2399 f->cache.allow_compat,
2400 SECCOMP_ARCH_COMPAT_NR);
2401 #endif /* SECCOMP_ARCH_COMPAT */
2403 __put_seccomp_filter(f);
2406 #endif /* CONFIG_SECCOMP_CACHE_DEBUG */