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 * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
111 * @ret: The return value of the installing process. It is set to the fd num
112 * upon success (>= 0).
113 * @completion: Indicates that the installing process has completed fd
114 * installation, or gone away (either due to successful
118 struct seccomp_kaddfd
{
126 /* To only be set on reply */
129 struct completion completion
;
130 struct list_head list
;
134 * struct notification - container for seccomp userspace notifications. Since
135 * most seccomp filters will not have notification listeners attached and this
136 * structure is fairly large, we store the notification-specific stuff in a
137 * separate structure.
139 * @request: A semaphore that users of this notification can wait on for
140 * changes. Actual reads and writes are still controlled with
141 * filter->notify_lock.
142 * @next_id: The id of the next request.
143 * @notifications: A list of struct seccomp_knotif elements.
145 struct notification
{
146 struct semaphore request
;
148 struct list_head notifications
;
151 #ifdef SECCOMP_ARCH_NATIVE
153 * struct action_cache - per-filter cache of seccomp actions per
156 * @allow_native: A bitmap where each bit represents whether the
157 * filter will always allow the syscall, for the
158 * native architecture.
159 * @allow_compat: A bitmap where each bit represents whether the
160 * filter will always allow the syscall, for the
161 * compat architecture.
163 struct action_cache
{
164 DECLARE_BITMAP(allow_native
, SECCOMP_ARCH_NATIVE_NR
);
165 #ifdef SECCOMP_ARCH_COMPAT
166 DECLARE_BITMAP(allow_compat
, SECCOMP_ARCH_COMPAT_NR
);
170 struct action_cache
{ };
172 static inline bool seccomp_cache_check_allow(const struct seccomp_filter
*sfilter
,
173 const struct seccomp_data
*sd
)
178 static inline void seccomp_cache_prepare(struct seccomp_filter
*sfilter
)
181 #endif /* SECCOMP_ARCH_NATIVE */
184 * struct seccomp_filter - container for seccomp BPF programs
186 * @refs: Reference count to manage the object lifetime.
187 * A filter's reference count is incremented for each directly
188 * attached task, once for the dependent filter, and if
189 * requested for the user notifier. When @refs reaches zero,
190 * the filter can be freed.
191 * @users: A filter's @users count is incremented for each directly
192 * attached task (filter installation, fork(), thread_sync),
193 * and once for the dependent filter (tracked in filter->prev).
194 * When it reaches zero it indicates that no direct or indirect
195 * users of that filter exist. No new tasks can get associated with
196 * this filter after reaching 0. The @users count is always smaller
197 * or equal to @refs. Hence, reaching 0 for @users does not mean
198 * the filter can be freed.
199 * @cache: cache of arch/syscall mappings to actions
200 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
201 * @prev: points to a previously installed, or inherited, filter
202 * @prog: the BPF program to evaluate
203 * @notif: the struct that holds all notification related information
204 * @notify_lock: A lock for all notification-related accesses.
205 * @wqh: A wait queue for poll if a notifier is in use.
207 * seccomp_filter objects are organized in a tree linked via the @prev
208 * pointer. For any task, it appears to be a singly-linked list starting
209 * with current->seccomp.filter, the most recently attached or inherited filter.
210 * However, multiple filters may share a @prev node, by way of fork(), which
211 * results in a unidirectional tree existing in memory. This is similar to
212 * how namespaces work.
214 * seccomp_filter objects should never be modified after being attached
215 * to a task_struct (other than @refs).
217 struct seccomp_filter
{
221 struct action_cache cache
;
222 struct seccomp_filter
*prev
;
223 struct bpf_prog
*prog
;
224 struct notification
*notif
;
225 struct mutex notify_lock
;
226 wait_queue_head_t wqh
;
229 /* Limit any path through the tree to 256KB worth of instructions. */
230 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
233 * Endianness is explicitly ignored and left for BPF program authors to manage
234 * as per the specific architecture.
236 static void populate_seccomp_data(struct seccomp_data
*sd
)
239 * Instead of using current_pt_reg(), we're already doing the work
240 * to safely fetch "current", so just use "task" everywhere below.
242 struct task_struct
*task
= current
;
243 struct pt_regs
*regs
= task_pt_regs(task
);
244 unsigned long args
[6];
246 sd
->nr
= syscall_get_nr(task
, regs
);
247 sd
->arch
= syscall_get_arch(task
);
248 syscall_get_arguments(task
, regs
, args
);
249 sd
->args
[0] = args
[0];
250 sd
->args
[1] = args
[1];
251 sd
->args
[2] = args
[2];
252 sd
->args
[3] = args
[3];
253 sd
->args
[4] = args
[4];
254 sd
->args
[5] = args
[5];
255 sd
->instruction_pointer
= KSTK_EIP(task
);
259 * seccomp_check_filter - verify seccomp filter code
260 * @filter: filter to verify
261 * @flen: length of filter
263 * Takes a previously checked filter (by bpf_check_classic) and
264 * redirects all filter code that loads struct sk_buff data
265 * and related data through seccomp_bpf_load. It also
266 * enforces length and alignment checking of those loads.
268 * Returns 0 if the rule set is legal or -EINVAL if not.
270 static int seccomp_check_filter(struct sock_filter
*filter
, unsigned int flen
)
273 for (pc
= 0; pc
< flen
; pc
++) {
274 struct sock_filter
*ftest
= &filter
[pc
];
275 u16 code
= ftest
->code
;
279 case BPF_LD
| BPF_W
| BPF_ABS
:
280 ftest
->code
= BPF_LDX
| BPF_W
| BPF_ABS
;
281 /* 32-bit aligned and not out of bounds. */
282 if (k
>= sizeof(struct seccomp_data
) || k
& 3)
285 case BPF_LD
| BPF_W
| BPF_LEN
:
286 ftest
->code
= BPF_LD
| BPF_IMM
;
287 ftest
->k
= sizeof(struct seccomp_data
);
289 case BPF_LDX
| BPF_W
| BPF_LEN
:
290 ftest
->code
= BPF_LDX
| BPF_IMM
;
291 ftest
->k
= sizeof(struct seccomp_data
);
293 /* Explicitly include allowed calls. */
294 case BPF_RET
| BPF_K
:
295 case BPF_RET
| BPF_A
:
296 case BPF_ALU
| BPF_ADD
| BPF_K
:
297 case BPF_ALU
| BPF_ADD
| BPF_X
:
298 case BPF_ALU
| BPF_SUB
| BPF_K
:
299 case BPF_ALU
| BPF_SUB
| BPF_X
:
300 case BPF_ALU
| BPF_MUL
| BPF_K
:
301 case BPF_ALU
| BPF_MUL
| BPF_X
:
302 case BPF_ALU
| BPF_DIV
| BPF_K
:
303 case BPF_ALU
| BPF_DIV
| BPF_X
:
304 case BPF_ALU
| BPF_AND
| BPF_K
:
305 case BPF_ALU
| BPF_AND
| BPF_X
:
306 case BPF_ALU
| BPF_OR
| BPF_K
:
307 case BPF_ALU
| BPF_OR
| BPF_X
:
308 case BPF_ALU
| BPF_XOR
| BPF_K
:
309 case BPF_ALU
| BPF_XOR
| BPF_X
:
310 case BPF_ALU
| BPF_LSH
| BPF_K
:
311 case BPF_ALU
| BPF_LSH
| BPF_X
:
312 case BPF_ALU
| BPF_RSH
| BPF_K
:
313 case BPF_ALU
| BPF_RSH
| BPF_X
:
314 case BPF_ALU
| BPF_NEG
:
315 case BPF_LD
| BPF_IMM
:
316 case BPF_LDX
| BPF_IMM
:
317 case BPF_MISC
| BPF_TAX
:
318 case BPF_MISC
| BPF_TXA
:
319 case BPF_LD
| BPF_MEM
:
320 case BPF_LDX
| BPF_MEM
:
323 case BPF_JMP
| BPF_JA
:
324 case BPF_JMP
| BPF_JEQ
| BPF_K
:
325 case BPF_JMP
| BPF_JEQ
| BPF_X
:
326 case BPF_JMP
| BPF_JGE
| BPF_K
:
327 case BPF_JMP
| BPF_JGE
| BPF_X
:
328 case BPF_JMP
| BPF_JGT
| BPF_K
:
329 case BPF_JMP
| BPF_JGT
| BPF_X
:
330 case BPF_JMP
| BPF_JSET
| BPF_K
:
331 case BPF_JMP
| BPF_JSET
| BPF_X
:
340 #ifdef SECCOMP_ARCH_NATIVE
341 static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap
,
345 if (unlikely(syscall_nr
< 0 || syscall_nr
>= bitmap_size
))
347 syscall_nr
= array_index_nospec(syscall_nr
, bitmap_size
);
349 return test_bit(syscall_nr
, bitmap
);
353 * seccomp_cache_check_allow - lookup seccomp cache
354 * @sfilter: The seccomp filter
355 * @sd: The seccomp data to lookup the cache with
357 * Returns true if the seccomp_data is cached and allowed.
359 static inline bool seccomp_cache_check_allow(const struct seccomp_filter
*sfilter
,
360 const struct seccomp_data
*sd
)
362 int syscall_nr
= sd
->nr
;
363 const struct action_cache
*cache
= &sfilter
->cache
;
365 #ifndef SECCOMP_ARCH_COMPAT
366 /* A native-only architecture doesn't need to check sd->arch. */
367 return seccomp_cache_check_allow_bitmap(cache
->allow_native
,
368 SECCOMP_ARCH_NATIVE_NR
,
371 if (likely(sd
->arch
== SECCOMP_ARCH_NATIVE
))
372 return seccomp_cache_check_allow_bitmap(cache
->allow_native
,
373 SECCOMP_ARCH_NATIVE_NR
,
375 if (likely(sd
->arch
== SECCOMP_ARCH_COMPAT
))
376 return seccomp_cache_check_allow_bitmap(cache
->allow_compat
,
377 SECCOMP_ARCH_COMPAT_NR
,
379 #endif /* SECCOMP_ARCH_COMPAT */
384 #endif /* SECCOMP_ARCH_NATIVE */
387 * seccomp_run_filters - evaluates all seccomp filters against @sd
388 * @sd: optional seccomp data to be passed to filters
389 * @match: stores struct seccomp_filter that resulted in the return value,
390 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
393 * Returns valid seccomp BPF response codes.
395 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
396 static u32
seccomp_run_filters(const struct seccomp_data
*sd
,
397 struct seccomp_filter
**match
)
399 u32 ret
= SECCOMP_RET_ALLOW
;
400 /* Make sure cross-thread synced filter points somewhere sane. */
401 struct seccomp_filter
*f
=
402 READ_ONCE(current
->seccomp
.filter
);
404 /* Ensure unexpected behavior doesn't result in failing open. */
405 if (WARN_ON(f
== NULL
))
406 return SECCOMP_RET_KILL_PROCESS
;
408 if (seccomp_cache_check_allow(f
, sd
))
409 return SECCOMP_RET_ALLOW
;
412 * All filters in the list are evaluated and the lowest BPF return
413 * value always takes priority (ignoring the DATA).
415 for (; f
; f
= f
->prev
) {
416 u32 cur_ret
= bpf_prog_run_pin_on_cpu(f
->prog
, sd
);
418 if (ACTION_ONLY(cur_ret
) < ACTION_ONLY(ret
)) {
425 #endif /* CONFIG_SECCOMP_FILTER */
427 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode
)
429 assert_spin_locked(¤t
->sighand
->siglock
);
431 if (current
->seccomp
.mode
&& current
->seccomp
.mode
!= seccomp_mode
)
437 void __weak
arch_seccomp_spec_mitigate(struct task_struct
*task
) { }
439 static inline void seccomp_assign_mode(struct task_struct
*task
,
440 unsigned long seccomp_mode
,
443 assert_spin_locked(&task
->sighand
->siglock
);
445 task
->seccomp
.mode
= seccomp_mode
;
447 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
450 smp_mb__before_atomic();
451 /* Assume default seccomp processes want spec flaw mitigation. */
452 if ((flags
& SECCOMP_FILTER_FLAG_SPEC_ALLOW
) == 0)
453 arch_seccomp_spec_mitigate(task
);
454 set_task_syscall_work(task
, SECCOMP
);
457 #ifdef CONFIG_SECCOMP_FILTER
458 /* Returns 1 if the parent is an ancestor of the child. */
459 static int is_ancestor(struct seccomp_filter
*parent
,
460 struct seccomp_filter
*child
)
462 /* NULL is the root ancestor. */
465 for (; child
; child
= child
->prev
)
472 * seccomp_can_sync_threads: checks if all threads can be synchronized
474 * Expects sighand and cred_guard_mutex locks to be held.
476 * Returns 0 on success, -ve on error, or the pid of a thread which was
477 * either not in the correct seccomp mode or did not have an ancestral
480 static inline pid_t
seccomp_can_sync_threads(void)
482 struct task_struct
*thread
, *caller
;
484 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
485 assert_spin_locked(¤t
->sighand
->siglock
);
487 /* Validate all threads being eligible for synchronization. */
489 for_each_thread(caller
, thread
) {
492 /* Skip current, since it is initiating the sync. */
493 if (thread
== caller
)
496 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
||
497 (thread
->seccomp
.mode
== SECCOMP_MODE_FILTER
&&
498 is_ancestor(thread
->seccomp
.filter
,
499 caller
->seccomp
.filter
)))
502 /* Return the first thread that cannot be synchronized. */
503 failed
= task_pid_vnr(thread
);
504 /* If the pid cannot be resolved, then return -ESRCH */
505 if (WARN_ON(failed
== 0))
513 static inline void seccomp_filter_free(struct seccomp_filter
*filter
)
516 bpf_prog_destroy(filter
->prog
);
521 static void __seccomp_filter_orphan(struct seccomp_filter
*orig
)
523 while (orig
&& refcount_dec_and_test(&orig
->users
)) {
524 if (waitqueue_active(&orig
->wqh
))
525 wake_up_poll(&orig
->wqh
, EPOLLHUP
);
530 static void __put_seccomp_filter(struct seccomp_filter
*orig
)
532 /* Clean up single-reference branches iteratively. */
533 while (orig
&& refcount_dec_and_test(&orig
->refs
)) {
534 struct seccomp_filter
*freeme
= orig
;
536 seccomp_filter_free(freeme
);
540 static void __seccomp_filter_release(struct seccomp_filter
*orig
)
542 /* Notify about any unused filters in the task's former filter tree. */
543 __seccomp_filter_orphan(orig
);
544 /* Finally drop all references to the task's former tree. */
545 __put_seccomp_filter(orig
);
549 * seccomp_filter_release - Detach the task from its filter tree,
550 * drop its reference count, and notify
551 * about unused filters
553 * This function should only be called when the task is exiting as
554 * it detaches it from its filter tree. As such, READ_ONCE() and
555 * barriers are not needed here, as would normally be needed.
557 void seccomp_filter_release(struct task_struct
*tsk
)
559 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
561 /* We are effectively holding the siglock by not having any sighand. */
562 WARN_ON(tsk
->sighand
!= NULL
);
564 /* Detach task from its filter tree. */
565 tsk
->seccomp
.filter
= NULL
;
566 __seccomp_filter_release(orig
);
570 * seccomp_sync_threads: sets all threads to use current's filter
572 * Expects sighand and cred_guard_mutex locks to be held, and for
573 * seccomp_can_sync_threads() to have returned success already
574 * without dropping the locks.
577 static inline void seccomp_sync_threads(unsigned long flags
)
579 struct task_struct
*thread
, *caller
;
581 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
582 assert_spin_locked(¤t
->sighand
->siglock
);
584 /* Synchronize all threads. */
586 for_each_thread(caller
, thread
) {
587 /* Skip current, since it needs no changes. */
588 if (thread
== caller
)
591 /* Get a task reference for the new leaf node. */
592 get_seccomp_filter(caller
);
595 * Drop the task reference to the shared ancestor since
596 * current's path will hold a reference. (This also
597 * allows a put before the assignment.)
599 __seccomp_filter_release(thread
->seccomp
.filter
);
601 /* Make our new filter tree visible. */
602 smp_store_release(&thread
->seccomp
.filter
,
603 caller
->seccomp
.filter
);
604 atomic_set(&thread
->seccomp
.filter_count
,
605 atomic_read(&caller
->seccomp
.filter_count
));
608 * Don't let an unprivileged task work around
609 * the no_new_privs restriction by creating
610 * a thread that sets it up, enters seccomp,
613 if (task_no_new_privs(caller
))
614 task_set_no_new_privs(thread
);
617 * Opt the other thread into seccomp if needed.
618 * As threads are considered to be trust-realm
619 * equivalent (see ptrace_may_access), it is safe to
620 * allow one thread to transition the other.
622 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
)
623 seccomp_assign_mode(thread
, SECCOMP_MODE_FILTER
,
629 * seccomp_prepare_filter: Prepares a seccomp filter for use.
630 * @fprog: BPF program to install
632 * Returns filter on success or an ERR_PTR on failure.
634 static struct seccomp_filter
*seccomp_prepare_filter(struct sock_fprog
*fprog
)
636 struct seccomp_filter
*sfilter
;
638 const bool save_orig
=
639 #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
645 if (fprog
->len
== 0 || fprog
->len
> BPF_MAXINSNS
)
646 return ERR_PTR(-EINVAL
);
648 BUG_ON(INT_MAX
/ fprog
->len
< sizeof(struct sock_filter
));
651 * Installing a seccomp filter requires that the task has
652 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
653 * This avoids scenarios where unprivileged tasks can affect the
654 * behavior of privileged children.
656 if (!task_no_new_privs(current
) &&
657 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN
))
658 return ERR_PTR(-EACCES
);
660 /* Allocate a new seccomp_filter */
661 sfilter
= kzalloc(sizeof(*sfilter
), GFP_KERNEL
| __GFP_NOWARN
);
663 return ERR_PTR(-ENOMEM
);
665 mutex_init(&sfilter
->notify_lock
);
666 ret
= bpf_prog_create_from_user(&sfilter
->prog
, fprog
,
667 seccomp_check_filter
, save_orig
);
673 refcount_set(&sfilter
->refs
, 1);
674 refcount_set(&sfilter
->users
, 1);
675 init_waitqueue_head(&sfilter
->wqh
);
681 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
682 * @user_filter: pointer to the user data containing a sock_fprog.
684 * Returns 0 on success and non-zero otherwise.
686 static struct seccomp_filter
*
687 seccomp_prepare_user_filter(const char __user
*user_filter
)
689 struct sock_fprog fprog
;
690 struct seccomp_filter
*filter
= ERR_PTR(-EFAULT
);
693 if (in_compat_syscall()) {
694 struct compat_sock_fprog fprog32
;
695 if (copy_from_user(&fprog32
, user_filter
, sizeof(fprog32
)))
697 fprog
.len
= fprog32
.len
;
698 fprog
.filter
= compat_ptr(fprog32
.filter
);
699 } else /* falls through to the if below. */
701 if (copy_from_user(&fprog
, user_filter
, sizeof(fprog
)))
703 filter
= seccomp_prepare_filter(&fprog
);
708 #ifdef SECCOMP_ARCH_NATIVE
710 * seccomp_is_const_allow - check if filter is constant allow with given data
711 * @fprog: The BPF programs
712 * @sd: The seccomp data to check against, only syscall number and arch
713 * number are considered constant.
715 static bool seccomp_is_const_allow(struct sock_fprog_kern
*fprog
,
716 struct seccomp_data
*sd
)
718 unsigned int reg_value
= 0;
722 if (WARN_ON_ONCE(!fprog
))
725 for (pc
= 0; pc
< fprog
->len
; pc
++) {
726 struct sock_filter
*insn
= &fprog
->filter
[pc
];
727 u16 code
= insn
->code
;
731 case BPF_LD
| BPF_W
| BPF_ABS
:
733 case offsetof(struct seccomp_data
, nr
):
736 case offsetof(struct seccomp_data
, arch
):
737 reg_value
= sd
->arch
;
740 /* can't optimize (non-constant value load) */
744 case BPF_RET
| BPF_K
:
745 /* reached return with constant values only, check allow */
746 return k
== SECCOMP_RET_ALLOW
;
747 case BPF_JMP
| BPF_JA
:
750 case BPF_JMP
| BPF_JEQ
| BPF_K
:
751 case BPF_JMP
| BPF_JGE
| BPF_K
:
752 case BPF_JMP
| BPF_JGT
| BPF_K
:
753 case BPF_JMP
| BPF_JSET
| BPF_K
:
754 switch (BPF_OP(code
)) {
756 op_res
= reg_value
== k
;
759 op_res
= reg_value
>= k
;
762 op_res
= reg_value
> k
;
765 op_res
= !!(reg_value
& k
);
768 /* can't optimize (unknown jump) */
772 pc
+= op_res
? insn
->jt
: insn
->jf
;
774 case BPF_ALU
| BPF_AND
| BPF_K
:
778 /* can't optimize (unknown insn) */
783 /* ran off the end of the filter?! */
788 static void seccomp_cache_prepare_bitmap(struct seccomp_filter
*sfilter
,
789 void *bitmap
, const void *bitmap_prev
,
790 size_t bitmap_size
, int arch
)
792 struct sock_fprog_kern
*fprog
= sfilter
->prog
->orig_prog
;
793 struct seccomp_data sd
;
797 /* The new filter must be as restrictive as the last. */
798 bitmap_copy(bitmap
, bitmap_prev
, bitmap_size
);
800 /* Before any filters, all syscalls are always allowed. */
801 bitmap_fill(bitmap
, bitmap_size
);
804 for (nr
= 0; nr
< bitmap_size
; nr
++) {
805 /* No bitmap change: not a cacheable action. */
806 if (!test_bit(nr
, bitmap
))
812 /* No bitmap change: continue to always allow. */
813 if (seccomp_is_const_allow(fprog
, &sd
))
817 * Not a cacheable action: always run filters.
818 * atomic clear_bit() not needed, filter not visible yet.
820 __clear_bit(nr
, bitmap
);
825 * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
826 * @sfilter: The seccomp filter
828 * Returns 0 if successful or -errno if error occurred.
830 static void seccomp_cache_prepare(struct seccomp_filter
*sfilter
)
832 struct action_cache
*cache
= &sfilter
->cache
;
833 const struct action_cache
*cache_prev
=
834 sfilter
->prev
? &sfilter
->prev
->cache
: NULL
;
836 seccomp_cache_prepare_bitmap(sfilter
, cache
->allow_native
,
837 cache_prev
? cache_prev
->allow_native
: NULL
,
838 SECCOMP_ARCH_NATIVE_NR
,
839 SECCOMP_ARCH_NATIVE
);
841 #ifdef SECCOMP_ARCH_COMPAT
842 seccomp_cache_prepare_bitmap(sfilter
, cache
->allow_compat
,
843 cache_prev
? cache_prev
->allow_compat
: NULL
,
844 SECCOMP_ARCH_COMPAT_NR
,
845 SECCOMP_ARCH_COMPAT
);
846 #endif /* SECCOMP_ARCH_COMPAT */
848 #endif /* SECCOMP_ARCH_NATIVE */
851 * seccomp_attach_filter: validate and attach filter
852 * @flags: flags to change filter behavior
853 * @filter: seccomp filter to add to the current process
855 * Caller must be holding current->sighand->siglock lock.
857 * Returns 0 on success, -ve on error, or
858 * - in TSYNC mode: the pid of a thread which was either not in the correct
859 * seccomp mode or did not have an ancestral seccomp filter
860 * - in NEW_LISTENER mode: the fd of the new listener
862 static long seccomp_attach_filter(unsigned int flags
,
863 struct seccomp_filter
*filter
)
865 unsigned long total_insns
;
866 struct seccomp_filter
*walker
;
868 assert_spin_locked(¤t
->sighand
->siglock
);
870 /* Validate resulting filter length. */
871 total_insns
= filter
->prog
->len
;
872 for (walker
= current
->seccomp
.filter
; walker
; walker
= walker
->prev
)
873 total_insns
+= walker
->prog
->len
+ 4; /* 4 instr penalty */
874 if (total_insns
> MAX_INSNS_PER_PATH
)
877 /* If thread sync has been requested, check that it is possible. */
878 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
) {
881 ret
= seccomp_can_sync_threads();
883 if (flags
& SECCOMP_FILTER_FLAG_TSYNC_ESRCH
)
890 /* Set log flag, if present. */
891 if (flags
& SECCOMP_FILTER_FLAG_LOG
)
895 * If there is an existing filter, make it the prev and don't drop its
898 filter
->prev
= current
->seccomp
.filter
;
899 seccomp_cache_prepare(filter
);
900 current
->seccomp
.filter
= filter
;
901 atomic_inc(¤t
->seccomp
.filter_count
);
903 /* Now that the new filter is in place, synchronize to all threads. */
904 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
905 seccomp_sync_threads(flags
);
910 static void __get_seccomp_filter(struct seccomp_filter
*filter
)
912 refcount_inc(&filter
->refs
);
915 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
916 void get_seccomp_filter(struct task_struct
*tsk
)
918 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
921 __get_seccomp_filter(orig
);
922 refcount_inc(&orig
->users
);
925 #endif /* CONFIG_SECCOMP_FILTER */
927 /* For use with seccomp_actions_logged */
928 #define SECCOMP_LOG_KILL_PROCESS (1 << 0)
929 #define SECCOMP_LOG_KILL_THREAD (1 << 1)
930 #define SECCOMP_LOG_TRAP (1 << 2)
931 #define SECCOMP_LOG_ERRNO (1 << 3)
932 #define SECCOMP_LOG_TRACE (1 << 4)
933 #define SECCOMP_LOG_LOG (1 << 5)
934 #define SECCOMP_LOG_ALLOW (1 << 6)
935 #define SECCOMP_LOG_USER_NOTIF (1 << 7)
937 static u32 seccomp_actions_logged
= SECCOMP_LOG_KILL_PROCESS
|
938 SECCOMP_LOG_KILL_THREAD
|
941 SECCOMP_LOG_USER_NOTIF
|
945 static inline void seccomp_log(unsigned long syscall
, long signr
, u32 action
,
951 case SECCOMP_RET_ALLOW
:
953 case SECCOMP_RET_TRAP
:
954 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRAP
;
956 case SECCOMP_RET_ERRNO
:
957 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_ERRNO
;
959 case SECCOMP_RET_TRACE
:
960 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRACE
;
962 case SECCOMP_RET_USER_NOTIF
:
963 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_USER_NOTIF
;
965 case SECCOMP_RET_LOG
:
966 log
= seccomp_actions_logged
& SECCOMP_LOG_LOG
;
968 case SECCOMP_RET_KILL_THREAD
:
969 log
= seccomp_actions_logged
& SECCOMP_LOG_KILL_THREAD
;
971 case SECCOMP_RET_KILL_PROCESS
:
973 log
= seccomp_actions_logged
& SECCOMP_LOG_KILL_PROCESS
;
977 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
978 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
979 * any action from being logged by removing the action name from the
980 * seccomp_actions_logged sysctl.
985 audit_seccomp(syscall
, signr
, action
);
989 * Secure computing mode 1 allows only read/write/exit/sigreturn.
990 * To be fully secure this must be combined with rlimit
991 * to limit the stack allocations too.
993 static const int mode1_syscalls
[] = {
994 __NR_seccomp_read
, __NR_seccomp_write
, __NR_seccomp_exit
, __NR_seccomp_sigreturn
,
995 -1, /* negative terminated */
998 static void __secure_computing_strict(int this_syscall
)
1000 const int *allowed_syscalls
= mode1_syscalls
;
1001 #ifdef CONFIG_COMPAT
1002 if (in_compat_syscall())
1003 allowed_syscalls
= get_compat_mode1_syscalls();
1006 if (*allowed_syscalls
== this_syscall
)
1008 } while (*++allowed_syscalls
!= -1);
1010 #ifdef SECCOMP_DEBUG
1013 seccomp_log(this_syscall
, SIGKILL
, SECCOMP_RET_KILL_THREAD
, true);
1017 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1018 void secure_computing_strict(int this_syscall
)
1020 int mode
= current
->seccomp
.mode
;
1022 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
1023 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
1026 if (mode
== SECCOMP_MODE_DISABLED
)
1028 else if (mode
== SECCOMP_MODE_STRICT
)
1029 __secure_computing_strict(this_syscall
);
1035 #ifdef CONFIG_SECCOMP_FILTER
1036 static u64
seccomp_next_notify_id(struct seccomp_filter
*filter
)
1039 * Note: overflow is ok here, the id just needs to be unique per
1042 lockdep_assert_held(&filter
->notify_lock
);
1043 return filter
->notif
->next_id
++;
1046 static void seccomp_handle_addfd(struct seccomp_kaddfd
*addfd
, struct seccomp_knotif
*n
)
1051 * Remove the notification, and reset the list pointers, indicating
1052 * that it has been handled.
1054 list_del_init(&addfd
->list
);
1056 fd
= receive_fd(addfd
->file
, addfd
->flags
);
1058 fd
= receive_fd_replace(addfd
->fd
, addfd
->file
, addfd
->flags
);
1061 if (addfd
->ioctl_flags
& SECCOMP_ADDFD_FLAG_SEND
) {
1062 /* If we fail reset and return an error to the notifier */
1064 n
->state
= SECCOMP_NOTIFY_SENT
;
1066 /* Return the FD we just added */
1074 * Mark the notification as completed. From this point, addfd mem
1075 * might be invalidated and we can't safely read it anymore.
1077 complete(&addfd
->completion
);
1080 static int seccomp_do_user_notification(int this_syscall
,
1081 struct seccomp_filter
*match
,
1082 const struct seccomp_data
*sd
)
1087 struct seccomp_knotif n
= {};
1088 struct seccomp_kaddfd
*addfd
, *tmp
;
1090 mutex_lock(&match
->notify_lock
);
1096 n
.state
= SECCOMP_NOTIFY_INIT
;
1098 n
.id
= seccomp_next_notify_id(match
);
1099 init_completion(&n
.ready
);
1100 list_add(&n
.list
, &match
->notif
->notifications
);
1101 INIT_LIST_HEAD(&n
.addfd
);
1103 up(&match
->notif
->request
);
1104 wake_up_poll(&match
->wqh
, EPOLLIN
| EPOLLRDNORM
);
1107 * This is where we wait for a reply from userspace.
1110 mutex_unlock(&match
->notify_lock
);
1111 err
= wait_for_completion_interruptible(&n
.ready
);
1112 mutex_lock(&match
->notify_lock
);
1116 addfd
= list_first_entry_or_null(&n
.addfd
,
1117 struct seccomp_kaddfd
, list
);
1118 /* Check if we were woken up by a addfd message */
1120 seccomp_handle_addfd(addfd
, &n
);
1122 } while (n
.state
!= SECCOMP_NOTIFY_REPLIED
);
1129 /* If there were any pending addfd calls, clear them out */
1130 list_for_each_entry_safe(addfd
, tmp
, &n
.addfd
, list
) {
1131 /* The process went away before we got a chance to handle it */
1132 addfd
->ret
= -ESRCH
;
1133 list_del_init(&addfd
->list
);
1134 complete(&addfd
->completion
);
1138 * Note that it's possible the listener died in between the time when
1139 * we were notified of a response (or a signal) and when we were able to
1140 * re-acquire the lock, so only delete from the list if the
1141 * notification actually exists.
1143 * Also note that this test is only valid because there's no way to
1144 * *reattach* to a notifier right now. If one is added, we'll need to
1145 * keep track of the notif itself and make sure they match here.
1150 mutex_unlock(&match
->notify_lock
);
1152 /* Userspace requests to continue the syscall. */
1153 if (flags
& SECCOMP_USER_NOTIF_FLAG_CONTINUE
)
1156 syscall_set_return_value(current
, current_pt_regs(),
1161 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
1162 const bool recheck_after_trace
)
1164 u32 filter_ret
, action
;
1165 struct seccomp_filter
*match
= NULL
;
1167 struct seccomp_data sd_local
;
1170 * Make sure that any changes to mode from another thread have
1171 * been seen after SYSCALL_WORK_SECCOMP was seen.
1176 populate_seccomp_data(&sd_local
);
1180 filter_ret
= seccomp_run_filters(sd
, &match
);
1181 data
= filter_ret
& SECCOMP_RET_DATA
;
1182 action
= filter_ret
& SECCOMP_RET_ACTION_FULL
;
1185 case SECCOMP_RET_ERRNO
:
1186 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1187 if (data
> MAX_ERRNO
)
1189 syscall_set_return_value(current
, current_pt_regs(),
1193 case SECCOMP_RET_TRAP
:
1194 /* Show the handler the original registers. */
1195 syscall_rollback(current
, current_pt_regs());
1196 /* Let the filter pass back 16 bits of data. */
1197 force_sig_seccomp(this_syscall
, data
, false);
1200 case SECCOMP_RET_TRACE
:
1201 /* We've been put in this state by the ptracer already. */
1202 if (recheck_after_trace
)
1205 /* ENOSYS these calls if there is no tracer attached. */
1206 if (!ptrace_event_enabled(current
, PTRACE_EVENT_SECCOMP
)) {
1207 syscall_set_return_value(current
,
1213 /* Allow the BPF to provide the event message */
1214 ptrace_event(PTRACE_EVENT_SECCOMP
, data
);
1216 * The delivery of a fatal signal during event
1217 * notification may silently skip tracer notification,
1218 * which could leave us with a potentially unmodified
1219 * syscall that the tracer would have liked to have
1220 * changed. Since the process is about to die, we just
1221 * force the syscall to be skipped and let the signal
1222 * kill the process and correctly handle any tracer exit
1225 if (fatal_signal_pending(current
))
1227 /* Check if the tracer forced the syscall to be skipped. */
1228 this_syscall
= syscall_get_nr(current
, current_pt_regs());
1229 if (this_syscall
< 0)
1233 * Recheck the syscall, since it may have changed. This
1234 * intentionally uses a NULL struct seccomp_data to force
1235 * a reload of all registers. This does not goto skip since
1236 * a skip would have already been reported.
1238 if (__seccomp_filter(this_syscall
, NULL
, true))
1243 case SECCOMP_RET_USER_NOTIF
:
1244 if (seccomp_do_user_notification(this_syscall
, match
, sd
))
1249 case SECCOMP_RET_LOG
:
1250 seccomp_log(this_syscall
, 0, action
, true);
1253 case SECCOMP_RET_ALLOW
:
1255 * Note that the "match" filter will always be NULL for
1256 * this action since SECCOMP_RET_ALLOW is the starting
1257 * state in seccomp_run_filters().
1261 case SECCOMP_RET_KILL_THREAD
:
1262 case SECCOMP_RET_KILL_PROCESS
:
1264 seccomp_log(this_syscall
, SIGSYS
, action
, true);
1265 /* Dump core only if this is the last remaining thread. */
1266 if (action
!= SECCOMP_RET_KILL_THREAD
||
1267 (atomic_read(¤t
->signal
->live
) == 1)) {
1268 /* Show the original registers in the dump. */
1269 syscall_rollback(current
, current_pt_regs());
1270 /* Trigger a coredump with SIGSYS */
1271 force_sig_seccomp(this_syscall
, data
, true);
1275 return -1; /* skip the syscall go directly to signal handling */
1281 seccomp_log(this_syscall
, 0, action
, match
? match
->log
: false);
1285 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
1286 const bool recheck_after_trace
)
1294 int __secure_computing(const struct seccomp_data
*sd
)
1296 int mode
= current
->seccomp
.mode
;
1299 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
1300 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
1303 this_syscall
= sd
? sd
->nr
:
1304 syscall_get_nr(current
, current_pt_regs());
1307 case SECCOMP_MODE_STRICT
:
1308 __secure_computing_strict(this_syscall
); /* may call do_exit */
1310 case SECCOMP_MODE_FILTER
:
1311 return __seccomp_filter(this_syscall
, sd
, false);
1316 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1318 long prctl_get_seccomp(void)
1320 return current
->seccomp
.mode
;
1324 * seccomp_set_mode_strict: internal function for setting strict seccomp
1326 * Once current->seccomp.mode is non-zero, it may not be changed.
1328 * Returns 0 on success or -EINVAL on failure.
1330 static long seccomp_set_mode_strict(void)
1332 const unsigned long seccomp_mode
= SECCOMP_MODE_STRICT
;
1335 spin_lock_irq(¤t
->sighand
->siglock
);
1337 if (!seccomp_may_assign_mode(seccomp_mode
))
1343 seccomp_assign_mode(current
, seccomp_mode
, 0);
1347 spin_unlock_irq(¤t
->sighand
->siglock
);
1352 #ifdef CONFIG_SECCOMP_FILTER
1353 static void seccomp_notify_free(struct seccomp_filter
*filter
)
1355 kfree(filter
->notif
);
1356 filter
->notif
= NULL
;
1359 static void seccomp_notify_detach(struct seccomp_filter
*filter
)
1361 struct seccomp_knotif
*knotif
;
1366 mutex_lock(&filter
->notify_lock
);
1369 * If this file is being closed because e.g. the task who owned it
1370 * died, let's wake everyone up who was waiting on us.
1372 list_for_each_entry(knotif
, &filter
->notif
->notifications
, list
) {
1373 if (knotif
->state
== SECCOMP_NOTIFY_REPLIED
)
1376 knotif
->state
= SECCOMP_NOTIFY_REPLIED
;
1377 knotif
->error
= -ENOSYS
;
1381 * We do not need to wake up any pending addfd messages, as
1382 * the notifier will do that for us, as this just looks
1383 * like a standard reply.
1385 complete(&knotif
->ready
);
1388 seccomp_notify_free(filter
);
1389 mutex_unlock(&filter
->notify_lock
);
1392 static int seccomp_notify_release(struct inode
*inode
, struct file
*file
)
1394 struct seccomp_filter
*filter
= file
->private_data
;
1396 seccomp_notify_detach(filter
);
1397 __put_seccomp_filter(filter
);
1401 /* must be called with notif_lock held */
1402 static inline struct seccomp_knotif
*
1403 find_notification(struct seccomp_filter
*filter
, u64 id
)
1405 struct seccomp_knotif
*cur
;
1407 lockdep_assert_held(&filter
->notify_lock
);
1409 list_for_each_entry(cur
, &filter
->notif
->notifications
, list
) {
1418 static long seccomp_notify_recv(struct seccomp_filter
*filter
,
1421 struct seccomp_knotif
*knotif
= NULL
, *cur
;
1422 struct seccomp_notif unotif
;
1425 /* Verify that we're not given garbage to keep struct extensible. */
1426 ret
= check_zeroed_user(buf
, sizeof(unotif
));
1432 memset(&unotif
, 0, sizeof(unotif
));
1434 ret
= down_interruptible(&filter
->notif
->request
);
1438 mutex_lock(&filter
->notify_lock
);
1439 list_for_each_entry(cur
, &filter
->notif
->notifications
, list
) {
1440 if (cur
->state
== SECCOMP_NOTIFY_INIT
) {
1447 * If we didn't find a notification, it could be that the task was
1448 * interrupted by a fatal signal between the time we were woken and
1449 * when we were able to acquire the rw lock.
1456 unotif
.id
= knotif
->id
;
1457 unotif
.pid
= task_pid_vnr(knotif
->task
);
1458 unotif
.data
= *(knotif
->data
);
1460 knotif
->state
= SECCOMP_NOTIFY_SENT
;
1461 wake_up_poll(&filter
->wqh
, EPOLLOUT
| EPOLLWRNORM
);
1464 mutex_unlock(&filter
->notify_lock
);
1466 if (ret
== 0 && copy_to_user(buf
, &unotif
, sizeof(unotif
))) {
1470 * Userspace screwed up. To make sure that we keep this
1471 * notification alive, let's reset it back to INIT. It
1472 * may have died when we released the lock, so we need to make
1473 * sure it's still around.
1475 mutex_lock(&filter
->notify_lock
);
1476 knotif
= find_notification(filter
, unotif
.id
);
1478 knotif
->state
= SECCOMP_NOTIFY_INIT
;
1479 up(&filter
->notif
->request
);
1481 mutex_unlock(&filter
->notify_lock
);
1487 static long seccomp_notify_send(struct seccomp_filter
*filter
,
1490 struct seccomp_notif_resp resp
= {};
1491 struct seccomp_knotif
*knotif
;
1494 if (copy_from_user(&resp
, buf
, sizeof(resp
)))
1497 if (resp
.flags
& ~SECCOMP_USER_NOTIF_FLAG_CONTINUE
)
1500 if ((resp
.flags
& SECCOMP_USER_NOTIF_FLAG_CONTINUE
) &&
1501 (resp
.error
|| resp
.val
))
1504 ret
= mutex_lock_interruptible(&filter
->notify_lock
);
1508 knotif
= find_notification(filter
, resp
.id
);
1514 /* Allow exactly one reply. */
1515 if (knotif
->state
!= SECCOMP_NOTIFY_SENT
) {
1521 knotif
->state
= SECCOMP_NOTIFY_REPLIED
;
1522 knotif
->error
= resp
.error
;
1523 knotif
->val
= resp
.val
;
1524 knotif
->flags
= resp
.flags
;
1525 complete(&knotif
->ready
);
1527 mutex_unlock(&filter
->notify_lock
);
1531 static long seccomp_notify_id_valid(struct seccomp_filter
*filter
,
1534 struct seccomp_knotif
*knotif
;
1538 if (copy_from_user(&id
, buf
, sizeof(id
)))
1541 ret
= mutex_lock_interruptible(&filter
->notify_lock
);
1545 knotif
= find_notification(filter
, id
);
1546 if (knotif
&& knotif
->state
== SECCOMP_NOTIFY_SENT
)
1551 mutex_unlock(&filter
->notify_lock
);
1555 static long seccomp_notify_addfd(struct seccomp_filter
*filter
,
1556 struct seccomp_notif_addfd __user
*uaddfd
,
1559 struct seccomp_notif_addfd addfd
;
1560 struct seccomp_knotif
*knotif
;
1561 struct seccomp_kaddfd kaddfd
;
1564 BUILD_BUG_ON(sizeof(addfd
) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0
);
1565 BUILD_BUG_ON(sizeof(addfd
) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST
);
1567 if (size
< SECCOMP_NOTIFY_ADDFD_SIZE_VER0
|| size
>= PAGE_SIZE
)
1570 ret
= copy_struct_from_user(&addfd
, sizeof(addfd
), uaddfd
, size
);
1574 if (addfd
.newfd_flags
& ~O_CLOEXEC
)
1577 if (addfd
.flags
& ~(SECCOMP_ADDFD_FLAG_SETFD
| SECCOMP_ADDFD_FLAG_SEND
))
1580 if (addfd
.newfd
&& !(addfd
.flags
& SECCOMP_ADDFD_FLAG_SETFD
))
1583 kaddfd
.file
= fget(addfd
.srcfd
);
1587 kaddfd
.ioctl_flags
= addfd
.flags
;
1588 kaddfd
.flags
= addfd
.newfd_flags
;
1589 kaddfd
.setfd
= addfd
.flags
& SECCOMP_ADDFD_FLAG_SETFD
;
1590 kaddfd
.fd
= addfd
.newfd
;
1591 init_completion(&kaddfd
.completion
);
1593 ret
= mutex_lock_interruptible(&filter
->notify_lock
);
1597 knotif
= find_notification(filter
, addfd
.id
);
1604 * We do not want to allow for FD injection to occur before the
1605 * notification has been picked up by a userspace handler, or after
1606 * the notification has been replied to.
1608 if (knotif
->state
!= SECCOMP_NOTIFY_SENT
) {
1613 if (addfd
.flags
& SECCOMP_ADDFD_FLAG_SEND
) {
1615 * Disallow queuing an atomic addfd + send reply while there are
1616 * some addfd requests still to process.
1618 * There is no clear reason to support it and allows us to keep
1619 * the loop on the other side straight-forward.
1621 if (!list_empty(&knotif
->addfd
)) {
1626 /* Allow exactly only one reply */
1627 knotif
->state
= SECCOMP_NOTIFY_REPLIED
;
1630 list_add(&kaddfd
.list
, &knotif
->addfd
);
1631 complete(&knotif
->ready
);
1632 mutex_unlock(&filter
->notify_lock
);
1634 /* Now we wait for it to be processed or be interrupted */
1635 ret
= wait_for_completion_interruptible(&kaddfd
.completion
);
1638 * We had a successful completion. The other side has already
1639 * removed us from the addfd queue, and
1640 * wait_for_completion_interruptible has a memory barrier upon
1641 * success that lets us read this value directly without
1648 mutex_lock(&filter
->notify_lock
);
1650 * Even though we were woken up by a signal and not a successful
1651 * completion, a completion may have happened in the mean time.
1653 * We need to check again if the addfd request has been handled,
1654 * and if not, we will remove it from the queue.
1656 if (list_empty(&kaddfd
.list
))
1659 list_del(&kaddfd
.list
);
1662 mutex_unlock(&filter
->notify_lock
);
1669 static long seccomp_notify_ioctl(struct file
*file
, unsigned int cmd
,
1672 struct seccomp_filter
*filter
= file
->private_data
;
1673 void __user
*buf
= (void __user
*)arg
;
1675 /* Fixed-size ioctls */
1677 case SECCOMP_IOCTL_NOTIF_RECV
:
1678 return seccomp_notify_recv(filter
, buf
);
1679 case SECCOMP_IOCTL_NOTIF_SEND
:
1680 return seccomp_notify_send(filter
, buf
);
1681 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR
:
1682 case SECCOMP_IOCTL_NOTIF_ID_VALID
:
1683 return seccomp_notify_id_valid(filter
, buf
);
1686 /* Extensible Argument ioctls */
1687 #define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1688 switch (EA_IOCTL(cmd
)) {
1689 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD
):
1690 return seccomp_notify_addfd(filter
, buf
, _IOC_SIZE(cmd
));
1696 static __poll_t
seccomp_notify_poll(struct file
*file
,
1697 struct poll_table_struct
*poll_tab
)
1699 struct seccomp_filter
*filter
= file
->private_data
;
1701 struct seccomp_knotif
*cur
;
1703 poll_wait(file
, &filter
->wqh
, poll_tab
);
1705 if (mutex_lock_interruptible(&filter
->notify_lock
) < 0)
1708 list_for_each_entry(cur
, &filter
->notif
->notifications
, list
) {
1709 if (cur
->state
== SECCOMP_NOTIFY_INIT
)
1710 ret
|= EPOLLIN
| EPOLLRDNORM
;
1711 if (cur
->state
== SECCOMP_NOTIFY_SENT
)
1712 ret
|= EPOLLOUT
| EPOLLWRNORM
;
1713 if ((ret
& EPOLLIN
) && (ret
& EPOLLOUT
))
1717 mutex_unlock(&filter
->notify_lock
);
1719 if (refcount_read(&filter
->users
) == 0)
1725 static const struct file_operations seccomp_notify_ops
= {
1726 .poll
= seccomp_notify_poll
,
1727 .release
= seccomp_notify_release
,
1728 .unlocked_ioctl
= seccomp_notify_ioctl
,
1729 .compat_ioctl
= seccomp_notify_ioctl
,
1732 static struct file
*init_listener(struct seccomp_filter
*filter
)
1736 ret
= ERR_PTR(-ENOMEM
);
1737 filter
->notif
= kzalloc(sizeof(*(filter
->notif
)), GFP_KERNEL
);
1741 sema_init(&filter
->notif
->request
, 0);
1742 filter
->notif
->next_id
= get_random_u64();
1743 INIT_LIST_HEAD(&filter
->notif
->notifications
);
1745 ret
= anon_inode_getfile("seccomp notify", &seccomp_notify_ops
,
1750 /* The file has a reference to it now */
1751 __get_seccomp_filter(filter
);
1755 seccomp_notify_free(filter
);
1761 * Does @new_child have a listener while an ancestor also has a listener?
1762 * If so, we'll want to reject this filter.
1763 * This only has to be tested for the current process, even in the TSYNC case,
1764 * because TSYNC installs @child with the same parent on all threads.
1765 * Note that @new_child is not hooked up to its parent at this point yet, so
1766 * we use current->seccomp.filter.
1768 static bool has_duplicate_listener(struct seccomp_filter
*new_child
)
1770 struct seccomp_filter
*cur
;
1772 /* must be protected against concurrent TSYNC */
1773 lockdep_assert_held(¤t
->sighand
->siglock
);
1775 if (!new_child
->notif
)
1777 for (cur
= current
->seccomp
.filter
; cur
; cur
= cur
->prev
) {
1786 * seccomp_set_mode_filter: internal function for setting seccomp filter
1787 * @flags: flags to change filter behavior
1788 * @filter: struct sock_fprog containing filter
1790 * This function may be called repeatedly to install additional filters.
1791 * Every filter successfully installed will be evaluated (in reverse order)
1792 * for each system call the task makes.
1794 * Once current->seccomp.mode is non-zero, it may not be changed.
1796 * Returns 0 on success or -EINVAL on failure.
1798 static long seccomp_set_mode_filter(unsigned int flags
,
1799 const char __user
*filter
)
1801 const unsigned long seccomp_mode
= SECCOMP_MODE_FILTER
;
1802 struct seccomp_filter
*prepared
= NULL
;
1805 struct file
*listener_f
= NULL
;
1807 /* Validate flags. */
1808 if (flags
& ~SECCOMP_FILTER_FLAG_MASK
)
1812 * In the successful case, NEW_LISTENER returns the new listener fd.
1813 * But in the failure case, TSYNC returns the thread that died. If you
1814 * combine these two flags, there's no way to tell whether something
1815 * succeeded or failed. So, let's disallow this combination if the user
1816 * has not explicitly requested no errors from TSYNC.
1818 if ((flags
& SECCOMP_FILTER_FLAG_TSYNC
) &&
1819 (flags
& SECCOMP_FILTER_FLAG_NEW_LISTENER
) &&
1820 ((flags
& SECCOMP_FILTER_FLAG_TSYNC_ESRCH
) == 0))
1823 /* Prepare the new filter before holding any locks. */
1824 prepared
= seccomp_prepare_user_filter(filter
);
1825 if (IS_ERR(prepared
))
1826 return PTR_ERR(prepared
);
1828 if (flags
& SECCOMP_FILTER_FLAG_NEW_LISTENER
) {
1829 listener
= get_unused_fd_flags(O_CLOEXEC
);
1835 listener_f
= init_listener(prepared
);
1836 if (IS_ERR(listener_f
)) {
1837 put_unused_fd(listener
);
1838 ret
= PTR_ERR(listener_f
);
1844 * Make sure we cannot change seccomp or nnp state via TSYNC
1845 * while another thread is in the middle of calling exec.
1847 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
&&
1848 mutex_lock_killable(¤t
->signal
->cred_guard_mutex
))
1851 spin_lock_irq(¤t
->sighand
->siglock
);
1853 if (!seccomp_may_assign_mode(seccomp_mode
))
1856 if (has_duplicate_listener(prepared
)) {
1861 ret
= seccomp_attach_filter(flags
, prepared
);
1864 /* Do not free the successfully attached filter. */
1867 seccomp_assign_mode(current
, seccomp_mode
, flags
);
1869 spin_unlock_irq(¤t
->sighand
->siglock
);
1870 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
1871 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
1873 if (flags
& SECCOMP_FILTER_FLAG_NEW_LISTENER
) {
1875 listener_f
->private_data
= NULL
;
1877 put_unused_fd(listener
);
1878 seccomp_notify_detach(prepared
);
1880 fd_install(listener
, listener_f
);
1885 seccomp_filter_free(prepared
);
1889 static inline long seccomp_set_mode_filter(unsigned int flags
,
1890 const char __user
*filter
)
1896 static long seccomp_get_action_avail(const char __user
*uaction
)
1900 if (copy_from_user(&action
, uaction
, sizeof(action
)))
1904 case SECCOMP_RET_KILL_PROCESS
:
1905 case SECCOMP_RET_KILL_THREAD
:
1906 case SECCOMP_RET_TRAP
:
1907 case SECCOMP_RET_ERRNO
:
1908 case SECCOMP_RET_USER_NOTIF
:
1909 case SECCOMP_RET_TRACE
:
1910 case SECCOMP_RET_LOG
:
1911 case SECCOMP_RET_ALLOW
:
1920 static long seccomp_get_notif_sizes(void __user
*usizes
)
1922 struct seccomp_notif_sizes sizes
= {
1923 .seccomp_notif
= sizeof(struct seccomp_notif
),
1924 .seccomp_notif_resp
= sizeof(struct seccomp_notif_resp
),
1925 .seccomp_data
= sizeof(struct seccomp_data
),
1928 if (copy_to_user(usizes
, &sizes
, sizeof(sizes
)))
1934 /* Common entry point for both prctl and syscall. */
1935 static long do_seccomp(unsigned int op
, unsigned int flags
,
1939 case SECCOMP_SET_MODE_STRICT
:
1940 if (flags
!= 0 || uargs
!= NULL
)
1942 return seccomp_set_mode_strict();
1943 case SECCOMP_SET_MODE_FILTER
:
1944 return seccomp_set_mode_filter(flags
, uargs
);
1945 case SECCOMP_GET_ACTION_AVAIL
:
1949 return seccomp_get_action_avail(uargs
);
1950 case SECCOMP_GET_NOTIF_SIZES
:
1954 return seccomp_get_notif_sizes(uargs
);
1960 SYSCALL_DEFINE3(seccomp
, unsigned int, op
, unsigned int, flags
,
1961 void __user
*, uargs
)
1963 return do_seccomp(op
, flags
, uargs
);
1967 * prctl_set_seccomp: configures current->seccomp.mode
1968 * @seccomp_mode: requested mode to use
1969 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1971 * Returns 0 on success or -EINVAL on failure.
1973 long prctl_set_seccomp(unsigned long seccomp_mode
, void __user
*filter
)
1978 switch (seccomp_mode
) {
1979 case SECCOMP_MODE_STRICT
:
1980 op
= SECCOMP_SET_MODE_STRICT
;
1982 * Setting strict mode through prctl always ignored filter,
1983 * so make sure it is always NULL here to pass the internal
1984 * check in do_seccomp().
1988 case SECCOMP_MODE_FILTER
:
1989 op
= SECCOMP_SET_MODE_FILTER
;
1996 /* prctl interface doesn't have flags, so they are always zero. */
1997 return do_seccomp(op
, 0, uargs
);
2000 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
2001 static struct seccomp_filter
*get_nth_filter(struct task_struct
*task
,
2002 unsigned long filter_off
)
2004 struct seccomp_filter
*orig
, *filter
;
2005 unsigned long count
;
2008 * Note: this is only correct because the caller should be the (ptrace)
2009 * tracer of the task, otherwise lock_task_sighand is needed.
2011 spin_lock_irq(&task
->sighand
->siglock
);
2013 if (task
->seccomp
.mode
!= SECCOMP_MODE_FILTER
) {
2014 spin_unlock_irq(&task
->sighand
->siglock
);
2015 return ERR_PTR(-EINVAL
);
2018 orig
= task
->seccomp
.filter
;
2019 __get_seccomp_filter(orig
);
2020 spin_unlock_irq(&task
->sighand
->siglock
);
2023 for (filter
= orig
; filter
; filter
= filter
->prev
)
2026 if (filter_off
>= count
) {
2027 filter
= ERR_PTR(-ENOENT
);
2031 count
-= filter_off
;
2032 for (filter
= orig
; filter
&& count
> 1; filter
= filter
->prev
)
2035 if (WARN_ON(count
!= 1 || !filter
)) {
2036 filter
= ERR_PTR(-ENOENT
);
2040 __get_seccomp_filter(filter
);
2043 __put_seccomp_filter(orig
);
2047 long seccomp_get_filter(struct task_struct
*task
, unsigned long filter_off
,
2050 struct seccomp_filter
*filter
;
2051 struct sock_fprog_kern
*fprog
;
2054 if (!capable(CAP_SYS_ADMIN
) ||
2055 current
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
) {
2059 filter
= get_nth_filter(task
, filter_off
);
2061 return PTR_ERR(filter
);
2063 fprog
= filter
->prog
->orig_prog
;
2065 /* This must be a new non-cBPF filter, since we save
2066 * every cBPF filter's orig_prog above when
2067 * CONFIG_CHECKPOINT_RESTORE is enabled.
2077 if (copy_to_user(data
, fprog
->filter
, bpf_classic_proglen(fprog
)))
2081 __put_seccomp_filter(filter
);
2085 long seccomp_get_metadata(struct task_struct
*task
,
2086 unsigned long size
, void __user
*data
)
2089 struct seccomp_filter
*filter
;
2090 struct seccomp_metadata kmd
= {};
2092 if (!capable(CAP_SYS_ADMIN
) ||
2093 current
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
) {
2097 size
= min_t(unsigned long, size
, sizeof(kmd
));
2099 if (size
< sizeof(kmd
.filter_off
))
2102 if (copy_from_user(&kmd
.filter_off
, data
, sizeof(kmd
.filter_off
)))
2105 filter
= get_nth_filter(task
, kmd
.filter_off
);
2107 return PTR_ERR(filter
);
2110 kmd
.flags
|= SECCOMP_FILTER_FLAG_LOG
;
2113 if (copy_to_user(data
, &kmd
, size
))
2116 __put_seccomp_filter(filter
);
2121 #ifdef CONFIG_SYSCTL
2123 /* Human readable action names for friendly sysctl interaction */
2124 #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
2125 #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
2126 #define SECCOMP_RET_TRAP_NAME "trap"
2127 #define SECCOMP_RET_ERRNO_NAME "errno"
2128 #define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
2129 #define SECCOMP_RET_TRACE_NAME "trace"
2130 #define SECCOMP_RET_LOG_NAME "log"
2131 #define SECCOMP_RET_ALLOW_NAME "allow"
2133 static const char seccomp_actions_avail
[] =
2134 SECCOMP_RET_KILL_PROCESS_NAME
" "
2135 SECCOMP_RET_KILL_THREAD_NAME
" "
2136 SECCOMP_RET_TRAP_NAME
" "
2137 SECCOMP_RET_ERRNO_NAME
" "
2138 SECCOMP_RET_USER_NOTIF_NAME
" "
2139 SECCOMP_RET_TRACE_NAME
" "
2140 SECCOMP_RET_LOG_NAME
" "
2141 SECCOMP_RET_ALLOW_NAME
;
2143 struct seccomp_log_name
{
2148 static const struct seccomp_log_name seccomp_log_names
[] = {
2149 { SECCOMP_LOG_KILL_PROCESS
, SECCOMP_RET_KILL_PROCESS_NAME
},
2150 { SECCOMP_LOG_KILL_THREAD
, SECCOMP_RET_KILL_THREAD_NAME
},
2151 { SECCOMP_LOG_TRAP
, SECCOMP_RET_TRAP_NAME
},
2152 { SECCOMP_LOG_ERRNO
, SECCOMP_RET_ERRNO_NAME
},
2153 { SECCOMP_LOG_USER_NOTIF
, SECCOMP_RET_USER_NOTIF_NAME
},
2154 { SECCOMP_LOG_TRACE
, SECCOMP_RET_TRACE_NAME
},
2155 { SECCOMP_LOG_LOG
, SECCOMP_RET_LOG_NAME
},
2156 { SECCOMP_LOG_ALLOW
, SECCOMP_RET_ALLOW_NAME
},
2160 static bool seccomp_names_from_actions_logged(char *names
, size_t size
,
2164 const struct seccomp_log_name
*cur
;
2165 bool append_sep
= false;
2167 for (cur
= seccomp_log_names
; cur
->name
&& size
; cur
++) {
2170 if (!(actions_logged
& cur
->log
))
2174 ret
= strscpy(names
, sep
, size
);
2183 ret
= strscpy(names
, cur
->name
, size
);
2194 static bool seccomp_action_logged_from_name(u32
*action_logged
,
2197 const struct seccomp_log_name
*cur
;
2199 for (cur
= seccomp_log_names
; cur
->name
; cur
++) {
2200 if (!strcmp(cur
->name
, name
)) {
2201 *action_logged
= cur
->log
;
2209 static bool seccomp_actions_logged_from_names(u32
*actions_logged
, char *names
)
2213 *actions_logged
= 0;
2214 while ((name
= strsep(&names
, " ")) && *name
) {
2215 u32 action_logged
= 0;
2217 if (!seccomp_action_logged_from_name(&action_logged
, name
))
2220 *actions_logged
|= action_logged
;
2226 static int read_actions_logged(struct ctl_table
*ro_table
, void *buffer
,
2227 size_t *lenp
, loff_t
*ppos
)
2229 char names
[sizeof(seccomp_actions_avail
)];
2230 struct ctl_table table
;
2232 memset(names
, 0, sizeof(names
));
2234 if (!seccomp_names_from_actions_logged(names
, sizeof(names
),
2235 seccomp_actions_logged
, " "))
2240 table
.maxlen
= sizeof(names
);
2241 return proc_dostring(&table
, 0, buffer
, lenp
, ppos
);
2244 static int write_actions_logged(struct ctl_table
*ro_table
, void *buffer
,
2245 size_t *lenp
, loff_t
*ppos
, u32
*actions_logged
)
2247 char names
[sizeof(seccomp_actions_avail
)];
2248 struct ctl_table table
;
2251 if (!capable(CAP_SYS_ADMIN
))
2254 memset(names
, 0, sizeof(names
));
2258 table
.maxlen
= sizeof(names
);
2259 ret
= proc_dostring(&table
, 1, buffer
, lenp
, ppos
);
2263 if (!seccomp_actions_logged_from_names(actions_logged
, table
.data
))
2266 if (*actions_logged
& SECCOMP_LOG_ALLOW
)
2269 seccomp_actions_logged
= *actions_logged
;
2273 static void audit_actions_logged(u32 actions_logged
, u32 old_actions_logged
,
2276 char names
[sizeof(seccomp_actions_avail
)];
2277 char old_names
[sizeof(seccomp_actions_avail
)];
2278 const char *new = names
;
2279 const char *old
= old_names
;
2284 memset(names
, 0, sizeof(names
));
2285 memset(old_names
, 0, sizeof(old_names
));
2289 else if (!actions_logged
)
2291 else if (!seccomp_names_from_actions_logged(names
, sizeof(names
),
2292 actions_logged
, ","))
2295 if (!old_actions_logged
)
2297 else if (!seccomp_names_from_actions_logged(old_names
,
2299 old_actions_logged
, ","))
2302 return audit_seccomp_actions_logged(new, old
, !ret
);
2305 static int seccomp_actions_logged_handler(struct ctl_table
*ro_table
, int write
,
2306 void *buffer
, size_t *lenp
,
2312 u32 actions_logged
= 0;
2313 u32 old_actions_logged
= seccomp_actions_logged
;
2315 ret
= write_actions_logged(ro_table
, buffer
, lenp
, ppos
,
2317 audit_actions_logged(actions_logged
, old_actions_logged
, ret
);
2319 ret
= read_actions_logged(ro_table
, buffer
, lenp
, ppos
);
2324 static struct ctl_path seccomp_sysctl_path
[] = {
2325 { .procname
= "kernel", },
2326 { .procname
= "seccomp", },
2330 static struct ctl_table seccomp_sysctl_table
[] = {
2332 .procname
= "actions_avail",
2333 .data
= (void *) &seccomp_actions_avail
,
2334 .maxlen
= sizeof(seccomp_actions_avail
),
2336 .proc_handler
= proc_dostring
,
2339 .procname
= "actions_logged",
2341 .proc_handler
= seccomp_actions_logged_handler
,
2346 static int __init
seccomp_sysctl_init(void)
2348 struct ctl_table_header
*hdr
;
2350 hdr
= register_sysctl_paths(seccomp_sysctl_path
, seccomp_sysctl_table
);
2352 pr_warn("sysctl registration failed\n");
2354 kmemleak_not_leak(hdr
);
2359 device_initcall(seccomp_sysctl_init
)
2361 #endif /* CONFIG_SYSCTL */
2363 #ifdef CONFIG_SECCOMP_CACHE_DEBUG
2364 /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2365 static void proc_pid_seccomp_cache_arch(struct seq_file
*m
, const char *name
,
2366 const void *bitmap
, size_t bitmap_size
)
2370 for (nr
= 0; nr
< bitmap_size
; nr
++) {
2371 bool cached
= test_bit(nr
, bitmap
);
2372 char *status
= cached
? "ALLOW" : "FILTER";
2374 seq_printf(m
, "%s %d %s\n", name
, nr
, status
);
2378 int proc_pid_seccomp_cache(struct seq_file
*m
, struct pid_namespace
*ns
,
2379 struct pid
*pid
, struct task_struct
*task
)
2381 struct seccomp_filter
*f
;
2382 unsigned long flags
;
2385 * We don't want some sandboxed process to know what their seccomp
2386 * filters consist of.
2388 if (!file_ns_capable(m
->file
, &init_user_ns
, CAP_SYS_ADMIN
))
2391 if (!lock_task_sighand(task
, &flags
))
2394 f
= READ_ONCE(task
->seccomp
.filter
);
2396 unlock_task_sighand(task
, &flags
);
2400 /* prevent filter from being freed while we are printing it */
2401 __get_seccomp_filter(f
);
2402 unlock_task_sighand(task
, &flags
);
2404 proc_pid_seccomp_cache_arch(m
, SECCOMP_ARCH_NATIVE_NAME
,
2405 f
->cache
.allow_native
,
2406 SECCOMP_ARCH_NATIVE_NR
);
2408 #ifdef SECCOMP_ARCH_COMPAT
2409 proc_pid_seccomp_cache_arch(m
, SECCOMP_ARCH_COMPAT_NAME
,
2410 f
->cache
.allow_compat
,
2411 SECCOMP_ARCH_COMPAT_NR
);
2412 #endif /* SECCOMP_ARCH_COMPAT */
2414 __put_seccomp_filter(f
);
2417 #endif /* CONFIG_SECCOMP_CACHE_DEBUG */