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
{
122 /* To only be set on reply */
124 struct completion completion
;
125 struct list_head list
;
129 * struct notification - container for seccomp userspace notifications. Since
130 * most seccomp filters will not have notification listeners attached and this
131 * structure is fairly large, we store the notification-specific stuff in a
132 * separate structure.
134 * @request: A semaphore that users of this notification can wait on for
135 * changes. Actual reads and writes are still controlled with
136 * filter->notify_lock.
137 * @next_id: The id of the next request.
138 * @notifications: A list of struct seccomp_knotif elements.
140 struct notification
{
141 struct semaphore request
;
143 struct list_head notifications
;
147 * struct seccomp_filter - container for seccomp BPF programs
149 * @refs: Reference count to manage the object lifetime.
150 * A filter's reference count is incremented for each directly
151 * attached task, once for the dependent filter, and if
152 * requested for the user notifier. When @refs reaches zero,
153 * the filter can be freed.
154 * @users: A filter's @users count is incremented for each directly
155 * attached task (filter installation, fork(), thread_sync),
156 * and once for the dependent filter (tracked in filter->prev).
157 * When it reaches zero it indicates that no direct or indirect
158 * users of that filter exist. No new tasks can get associated with
159 * this filter after reaching 0. The @users count is always smaller
160 * or equal to @refs. Hence, reaching 0 for @users does not mean
161 * the filter can be freed.
162 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
163 * @prev: points to a previously installed, or inherited, filter
164 * @prog: the BPF program to evaluate
165 * @notif: the struct that holds all notification related information
166 * @notify_lock: A lock for all notification-related accesses.
167 * @wqh: A wait queue for poll if a notifier is in use.
169 * seccomp_filter objects are organized in a tree linked via the @prev
170 * pointer. For any task, it appears to be a singly-linked list starting
171 * with current->seccomp.filter, the most recently attached or inherited filter.
172 * However, multiple filters may share a @prev node, by way of fork(), which
173 * results in a unidirectional tree existing in memory. This is similar to
174 * how namespaces work.
176 * seccomp_filter objects should never be modified after being attached
177 * to a task_struct (other than @refs).
179 struct seccomp_filter
{
183 struct seccomp_filter
*prev
;
184 struct bpf_prog
*prog
;
185 struct notification
*notif
;
186 struct mutex notify_lock
;
187 wait_queue_head_t wqh
;
190 /* Limit any path through the tree to 256KB worth of instructions. */
191 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
194 * Endianness is explicitly ignored and left for BPF program authors to manage
195 * as per the specific architecture.
197 static void populate_seccomp_data(struct seccomp_data
*sd
)
200 * Instead of using current_pt_reg(), we're already doing the work
201 * to safely fetch "current", so just use "task" everywhere below.
203 struct task_struct
*task
= current
;
204 struct pt_regs
*regs
= task_pt_regs(task
);
205 unsigned long args
[6];
207 sd
->nr
= syscall_get_nr(task
, regs
);
208 sd
->arch
= syscall_get_arch(task
);
209 syscall_get_arguments(task
, regs
, args
);
210 sd
->args
[0] = args
[0];
211 sd
->args
[1] = args
[1];
212 sd
->args
[2] = args
[2];
213 sd
->args
[3] = args
[3];
214 sd
->args
[4] = args
[4];
215 sd
->args
[5] = args
[5];
216 sd
->instruction_pointer
= KSTK_EIP(task
);
220 * seccomp_check_filter - verify seccomp filter code
221 * @filter: filter to verify
222 * @flen: length of filter
224 * Takes a previously checked filter (by bpf_check_classic) and
225 * redirects all filter code that loads struct sk_buff data
226 * and related data through seccomp_bpf_load. It also
227 * enforces length and alignment checking of those loads.
229 * Returns 0 if the rule set is legal or -EINVAL if not.
231 static int seccomp_check_filter(struct sock_filter
*filter
, unsigned int flen
)
234 for (pc
= 0; pc
< flen
; pc
++) {
235 struct sock_filter
*ftest
= &filter
[pc
];
236 u16 code
= ftest
->code
;
240 case BPF_LD
| BPF_W
| BPF_ABS
:
241 ftest
->code
= BPF_LDX
| BPF_W
| BPF_ABS
;
242 /* 32-bit aligned and not out of bounds. */
243 if (k
>= sizeof(struct seccomp_data
) || k
& 3)
246 case BPF_LD
| BPF_W
| BPF_LEN
:
247 ftest
->code
= BPF_LD
| BPF_IMM
;
248 ftest
->k
= sizeof(struct seccomp_data
);
250 case BPF_LDX
| BPF_W
| BPF_LEN
:
251 ftest
->code
= BPF_LDX
| BPF_IMM
;
252 ftest
->k
= sizeof(struct seccomp_data
);
254 /* Explicitly include allowed calls. */
255 case BPF_RET
| BPF_K
:
256 case BPF_RET
| BPF_A
:
257 case BPF_ALU
| BPF_ADD
| BPF_K
:
258 case BPF_ALU
| BPF_ADD
| BPF_X
:
259 case BPF_ALU
| BPF_SUB
| BPF_K
:
260 case BPF_ALU
| BPF_SUB
| BPF_X
:
261 case BPF_ALU
| BPF_MUL
| BPF_K
:
262 case BPF_ALU
| BPF_MUL
| BPF_X
:
263 case BPF_ALU
| BPF_DIV
| BPF_K
:
264 case BPF_ALU
| BPF_DIV
| BPF_X
:
265 case BPF_ALU
| BPF_AND
| BPF_K
:
266 case BPF_ALU
| BPF_AND
| BPF_X
:
267 case BPF_ALU
| BPF_OR
| BPF_K
:
268 case BPF_ALU
| BPF_OR
| BPF_X
:
269 case BPF_ALU
| BPF_XOR
| BPF_K
:
270 case BPF_ALU
| BPF_XOR
| BPF_X
:
271 case BPF_ALU
| BPF_LSH
| BPF_K
:
272 case BPF_ALU
| BPF_LSH
| BPF_X
:
273 case BPF_ALU
| BPF_RSH
| BPF_K
:
274 case BPF_ALU
| BPF_RSH
| BPF_X
:
275 case BPF_ALU
| BPF_NEG
:
276 case BPF_LD
| BPF_IMM
:
277 case BPF_LDX
| BPF_IMM
:
278 case BPF_MISC
| BPF_TAX
:
279 case BPF_MISC
| BPF_TXA
:
280 case BPF_LD
| BPF_MEM
:
281 case BPF_LDX
| BPF_MEM
:
284 case BPF_JMP
| BPF_JA
:
285 case BPF_JMP
| BPF_JEQ
| BPF_K
:
286 case BPF_JMP
| BPF_JEQ
| BPF_X
:
287 case BPF_JMP
| BPF_JGE
| BPF_K
:
288 case BPF_JMP
| BPF_JGE
| BPF_X
:
289 case BPF_JMP
| BPF_JGT
| BPF_K
:
290 case BPF_JMP
| BPF_JGT
| BPF_X
:
291 case BPF_JMP
| BPF_JSET
| BPF_K
:
292 case BPF_JMP
| BPF_JSET
| BPF_X
:
302 * seccomp_run_filters - evaluates all seccomp filters against @sd
303 * @sd: optional seccomp data to be passed to filters
304 * @match: stores struct seccomp_filter that resulted in the return value,
305 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
308 * Returns valid seccomp BPF response codes.
310 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
311 static u32
seccomp_run_filters(const struct seccomp_data
*sd
,
312 struct seccomp_filter
**match
)
314 u32 ret
= SECCOMP_RET_ALLOW
;
315 /* Make sure cross-thread synced filter points somewhere sane. */
316 struct seccomp_filter
*f
=
317 READ_ONCE(current
->seccomp
.filter
);
319 /* Ensure unexpected behavior doesn't result in failing open. */
320 if (WARN_ON(f
== NULL
))
321 return SECCOMP_RET_KILL_PROCESS
;
324 * All filters in the list are evaluated and the lowest BPF return
325 * value always takes priority (ignoring the DATA).
327 for (; f
; f
= f
->prev
) {
328 u32 cur_ret
= bpf_prog_run_pin_on_cpu(f
->prog
, sd
);
330 if (ACTION_ONLY(cur_ret
) < ACTION_ONLY(ret
)) {
337 #endif /* CONFIG_SECCOMP_FILTER */
339 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode
)
341 assert_spin_locked(¤t
->sighand
->siglock
);
343 if (current
->seccomp
.mode
&& current
->seccomp
.mode
!= seccomp_mode
)
349 void __weak
arch_seccomp_spec_mitigate(struct task_struct
*task
) { }
351 static inline void seccomp_assign_mode(struct task_struct
*task
,
352 unsigned long seccomp_mode
,
355 assert_spin_locked(&task
->sighand
->siglock
);
357 task
->seccomp
.mode
= seccomp_mode
;
359 * Make sure TIF_SECCOMP cannot be set before the mode (and
362 smp_mb__before_atomic();
363 /* Assume default seccomp processes want spec flaw mitigation. */
364 if ((flags
& SECCOMP_FILTER_FLAG_SPEC_ALLOW
) == 0)
365 arch_seccomp_spec_mitigate(task
);
366 set_tsk_thread_flag(task
, TIF_SECCOMP
);
369 #ifdef CONFIG_SECCOMP_FILTER
370 /* Returns 1 if the parent is an ancestor of the child. */
371 static int is_ancestor(struct seccomp_filter
*parent
,
372 struct seccomp_filter
*child
)
374 /* NULL is the root ancestor. */
377 for (; child
; child
= child
->prev
)
384 * seccomp_can_sync_threads: checks if all threads can be synchronized
386 * Expects sighand and cred_guard_mutex locks to be held.
388 * Returns 0 on success, -ve on error, or the pid of a thread which was
389 * either not in the correct seccomp mode or did not have an ancestral
392 static inline pid_t
seccomp_can_sync_threads(void)
394 struct task_struct
*thread
, *caller
;
396 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
397 assert_spin_locked(¤t
->sighand
->siglock
);
399 /* Validate all threads being eligible for synchronization. */
401 for_each_thread(caller
, thread
) {
404 /* Skip current, since it is initiating the sync. */
405 if (thread
== caller
)
408 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
||
409 (thread
->seccomp
.mode
== SECCOMP_MODE_FILTER
&&
410 is_ancestor(thread
->seccomp
.filter
,
411 caller
->seccomp
.filter
)))
414 /* Return the first thread that cannot be synchronized. */
415 failed
= task_pid_vnr(thread
);
416 /* If the pid cannot be resolved, then return -ESRCH */
417 if (WARN_ON(failed
== 0))
425 static inline void seccomp_filter_free(struct seccomp_filter
*filter
)
428 bpf_prog_destroy(filter
->prog
);
433 static void __seccomp_filter_orphan(struct seccomp_filter
*orig
)
435 while (orig
&& refcount_dec_and_test(&orig
->users
)) {
436 if (waitqueue_active(&orig
->wqh
))
437 wake_up_poll(&orig
->wqh
, EPOLLHUP
);
442 static void __put_seccomp_filter(struct seccomp_filter
*orig
)
444 /* Clean up single-reference branches iteratively. */
445 while (orig
&& refcount_dec_and_test(&orig
->refs
)) {
446 struct seccomp_filter
*freeme
= orig
;
448 seccomp_filter_free(freeme
);
452 static void __seccomp_filter_release(struct seccomp_filter
*orig
)
454 /* Notify about any unused filters in the task's former filter tree. */
455 __seccomp_filter_orphan(orig
);
456 /* Finally drop all references to the task's former tree. */
457 __put_seccomp_filter(orig
);
461 * seccomp_filter_release - Detach the task from its filter tree,
462 * drop its reference count, and notify
463 * about unused filters
465 * This function should only be called when the task is exiting as
466 * it detaches it from its filter tree. As such, READ_ONCE() and
467 * barriers are not needed here, as would normally be needed.
469 void seccomp_filter_release(struct task_struct
*tsk
)
471 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
473 /* Detach task from its filter tree. */
474 tsk
->seccomp
.filter
= NULL
;
475 __seccomp_filter_release(orig
);
479 * seccomp_sync_threads: sets all threads to use current's filter
481 * Expects sighand and cred_guard_mutex locks to be held, and for
482 * seccomp_can_sync_threads() to have returned success already
483 * without dropping the locks.
486 static inline void seccomp_sync_threads(unsigned long flags
)
488 struct task_struct
*thread
, *caller
;
490 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
491 assert_spin_locked(¤t
->sighand
->siglock
);
493 /* Synchronize all threads. */
495 for_each_thread(caller
, thread
) {
496 /* Skip current, since it needs no changes. */
497 if (thread
== caller
)
500 /* Get a task reference for the new leaf node. */
501 get_seccomp_filter(caller
);
504 * Drop the task reference to the shared ancestor since
505 * current's path will hold a reference. (This also
506 * allows a put before the assignment.)
508 __seccomp_filter_release(thread
->seccomp
.filter
);
510 /* Make our new filter tree visible. */
511 smp_store_release(&thread
->seccomp
.filter
,
512 caller
->seccomp
.filter
);
513 atomic_set(&thread
->seccomp
.filter_count
,
514 atomic_read(&thread
->seccomp
.filter_count
));
517 * Don't let an unprivileged task work around
518 * the no_new_privs restriction by creating
519 * a thread that sets it up, enters seccomp,
522 if (task_no_new_privs(caller
))
523 task_set_no_new_privs(thread
);
526 * Opt the other thread into seccomp if needed.
527 * As threads are considered to be trust-realm
528 * equivalent (see ptrace_may_access), it is safe to
529 * allow one thread to transition the other.
531 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
)
532 seccomp_assign_mode(thread
, SECCOMP_MODE_FILTER
,
538 * seccomp_prepare_filter: Prepares a seccomp filter for use.
539 * @fprog: BPF program to install
541 * Returns filter on success or an ERR_PTR on failure.
543 static struct seccomp_filter
*seccomp_prepare_filter(struct sock_fprog
*fprog
)
545 struct seccomp_filter
*sfilter
;
547 const bool save_orig
= IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
);
549 if (fprog
->len
== 0 || fprog
->len
> BPF_MAXINSNS
)
550 return ERR_PTR(-EINVAL
);
552 BUG_ON(INT_MAX
/ fprog
->len
< sizeof(struct sock_filter
));
555 * Installing a seccomp filter requires that the task has
556 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
557 * This avoids scenarios where unprivileged tasks can affect the
558 * behavior of privileged children.
560 if (!task_no_new_privs(current
) &&
561 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN
))
562 return ERR_PTR(-EACCES
);
564 /* Allocate a new seccomp_filter */
565 sfilter
= kzalloc(sizeof(*sfilter
), GFP_KERNEL
| __GFP_NOWARN
);
567 return ERR_PTR(-ENOMEM
);
569 mutex_init(&sfilter
->notify_lock
);
570 ret
= bpf_prog_create_from_user(&sfilter
->prog
, fprog
,
571 seccomp_check_filter
, save_orig
);
577 refcount_set(&sfilter
->refs
, 1);
578 refcount_set(&sfilter
->users
, 1);
579 init_waitqueue_head(&sfilter
->wqh
);
585 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
586 * @user_filter: pointer to the user data containing a sock_fprog.
588 * Returns 0 on success and non-zero otherwise.
590 static struct seccomp_filter
*
591 seccomp_prepare_user_filter(const char __user
*user_filter
)
593 struct sock_fprog fprog
;
594 struct seccomp_filter
*filter
= ERR_PTR(-EFAULT
);
597 if (in_compat_syscall()) {
598 struct compat_sock_fprog fprog32
;
599 if (copy_from_user(&fprog32
, user_filter
, sizeof(fprog32
)))
601 fprog
.len
= fprog32
.len
;
602 fprog
.filter
= compat_ptr(fprog32
.filter
);
603 } else /* falls through to the if below. */
605 if (copy_from_user(&fprog
, user_filter
, sizeof(fprog
)))
607 filter
= seccomp_prepare_filter(&fprog
);
613 * seccomp_attach_filter: validate and attach filter
614 * @flags: flags to change filter behavior
615 * @filter: seccomp filter to add to the current process
617 * Caller must be holding current->sighand->siglock lock.
619 * Returns 0 on success, -ve on error, or
620 * - in TSYNC mode: the pid of a thread which was either not in the correct
621 * seccomp mode or did not have an ancestral seccomp filter
622 * - in NEW_LISTENER mode: the fd of the new listener
624 static long seccomp_attach_filter(unsigned int flags
,
625 struct seccomp_filter
*filter
)
627 unsigned long total_insns
;
628 struct seccomp_filter
*walker
;
630 assert_spin_locked(¤t
->sighand
->siglock
);
632 /* Validate resulting filter length. */
633 total_insns
= filter
->prog
->len
;
634 for (walker
= current
->seccomp
.filter
; walker
; walker
= walker
->prev
)
635 total_insns
+= walker
->prog
->len
+ 4; /* 4 instr penalty */
636 if (total_insns
> MAX_INSNS_PER_PATH
)
639 /* If thread sync has been requested, check that it is possible. */
640 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
) {
643 ret
= seccomp_can_sync_threads();
645 if (flags
& SECCOMP_FILTER_FLAG_TSYNC_ESRCH
)
652 /* Set log flag, if present. */
653 if (flags
& SECCOMP_FILTER_FLAG_LOG
)
657 * If there is an existing filter, make it the prev and don't drop its
660 filter
->prev
= current
->seccomp
.filter
;
661 current
->seccomp
.filter
= filter
;
662 atomic_inc(¤t
->seccomp
.filter_count
);
664 /* Now that the new filter is in place, synchronize to all threads. */
665 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
666 seccomp_sync_threads(flags
);
671 static void __get_seccomp_filter(struct seccomp_filter
*filter
)
673 refcount_inc(&filter
->refs
);
676 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
677 void get_seccomp_filter(struct task_struct
*tsk
)
679 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
682 __get_seccomp_filter(orig
);
683 refcount_inc(&orig
->users
);
686 static void seccomp_init_siginfo(kernel_siginfo_t
*info
, int syscall
, int reason
)
689 info
->si_signo
= SIGSYS
;
690 info
->si_code
= SYS_SECCOMP
;
691 info
->si_call_addr
= (void __user
*)KSTK_EIP(current
);
692 info
->si_errno
= reason
;
693 info
->si_arch
= syscall_get_arch(current
);
694 info
->si_syscall
= syscall
;
698 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
699 * @syscall: syscall number to send to userland
700 * @reason: filter-supplied reason code to send to userland (via si_errno)
702 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
704 static void seccomp_send_sigsys(int syscall
, int reason
)
706 struct kernel_siginfo info
;
707 seccomp_init_siginfo(&info
, syscall
, reason
);
708 force_sig_info(&info
);
710 #endif /* CONFIG_SECCOMP_FILTER */
712 /* For use with seccomp_actions_logged */
713 #define SECCOMP_LOG_KILL_PROCESS (1 << 0)
714 #define SECCOMP_LOG_KILL_THREAD (1 << 1)
715 #define SECCOMP_LOG_TRAP (1 << 2)
716 #define SECCOMP_LOG_ERRNO (1 << 3)
717 #define SECCOMP_LOG_TRACE (1 << 4)
718 #define SECCOMP_LOG_LOG (1 << 5)
719 #define SECCOMP_LOG_ALLOW (1 << 6)
720 #define SECCOMP_LOG_USER_NOTIF (1 << 7)
722 static u32 seccomp_actions_logged
= SECCOMP_LOG_KILL_PROCESS
|
723 SECCOMP_LOG_KILL_THREAD
|
726 SECCOMP_LOG_USER_NOTIF
|
730 static inline void seccomp_log(unsigned long syscall
, long signr
, u32 action
,
736 case SECCOMP_RET_ALLOW
:
738 case SECCOMP_RET_TRAP
:
739 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRAP
;
741 case SECCOMP_RET_ERRNO
:
742 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_ERRNO
;
744 case SECCOMP_RET_TRACE
:
745 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRACE
;
747 case SECCOMP_RET_USER_NOTIF
:
748 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_USER_NOTIF
;
750 case SECCOMP_RET_LOG
:
751 log
= seccomp_actions_logged
& SECCOMP_LOG_LOG
;
753 case SECCOMP_RET_KILL_THREAD
:
754 log
= seccomp_actions_logged
& SECCOMP_LOG_KILL_THREAD
;
756 case SECCOMP_RET_KILL_PROCESS
:
758 log
= seccomp_actions_logged
& SECCOMP_LOG_KILL_PROCESS
;
762 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
763 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
764 * any action from being logged by removing the action name from the
765 * seccomp_actions_logged sysctl.
770 audit_seccomp(syscall
, signr
, action
);
774 * Secure computing mode 1 allows only read/write/exit/sigreturn.
775 * To be fully secure this must be combined with rlimit
776 * to limit the stack allocations too.
778 static const int mode1_syscalls
[] = {
779 __NR_seccomp_read
, __NR_seccomp_write
, __NR_seccomp_exit
, __NR_seccomp_sigreturn
,
780 -1, /* negative terminated */
783 static void __secure_computing_strict(int this_syscall
)
785 const int *allowed_syscalls
= mode1_syscalls
;
787 if (in_compat_syscall())
788 allowed_syscalls
= get_compat_mode1_syscalls();
791 if (*allowed_syscalls
== this_syscall
)
793 } while (*++allowed_syscalls
!= -1);
798 seccomp_log(this_syscall
, SIGKILL
, SECCOMP_RET_KILL_THREAD
, true);
802 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
803 void secure_computing_strict(int this_syscall
)
805 int mode
= current
->seccomp
.mode
;
807 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
808 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
811 if (mode
== SECCOMP_MODE_DISABLED
)
813 else if (mode
== SECCOMP_MODE_STRICT
)
814 __secure_computing_strict(this_syscall
);
820 #ifdef CONFIG_SECCOMP_FILTER
821 static u64
seccomp_next_notify_id(struct seccomp_filter
*filter
)
824 * Note: overflow is ok here, the id just needs to be unique per
827 lockdep_assert_held(&filter
->notify_lock
);
828 return filter
->notif
->next_id
++;
831 static void seccomp_handle_addfd(struct seccomp_kaddfd
*addfd
)
834 * Remove the notification, and reset the list pointers, indicating
835 * that it has been handled.
837 list_del_init(&addfd
->list
);
838 addfd
->ret
= receive_fd_replace(addfd
->fd
, addfd
->file
, addfd
->flags
);
839 complete(&addfd
->completion
);
842 static int seccomp_do_user_notification(int this_syscall
,
843 struct seccomp_filter
*match
,
844 const struct seccomp_data
*sd
)
849 struct seccomp_knotif n
= {};
850 struct seccomp_kaddfd
*addfd
, *tmp
;
852 mutex_lock(&match
->notify_lock
);
858 n
.state
= SECCOMP_NOTIFY_INIT
;
860 n
.id
= seccomp_next_notify_id(match
);
861 init_completion(&n
.ready
);
862 list_add(&n
.list
, &match
->notif
->notifications
);
863 INIT_LIST_HEAD(&n
.addfd
);
865 up(&match
->notif
->request
);
866 wake_up_poll(&match
->wqh
, EPOLLIN
| EPOLLRDNORM
);
867 mutex_unlock(&match
->notify_lock
);
870 * This is where we wait for a reply from userspace.
873 err
= wait_for_completion_interruptible(&n
.ready
);
874 mutex_lock(&match
->notify_lock
);
876 /* Check if we were woken up by a addfd message */
877 addfd
= list_first_entry_or_null(&n
.addfd
,
878 struct seccomp_kaddfd
, list
);
879 if (addfd
&& n
.state
!= SECCOMP_NOTIFY_REPLIED
) {
880 seccomp_handle_addfd(addfd
);
881 mutex_unlock(&match
->notify_lock
);
889 /* If there were any pending addfd calls, clear them out */
890 list_for_each_entry_safe(addfd
, tmp
, &n
.addfd
, list
) {
891 /* The process went away before we got a chance to handle it */
893 list_del_init(&addfd
->list
);
894 complete(&addfd
->completion
);
898 * Note that it's possible the listener died in between the time when
899 * we were notified of a response (or a signal) and when we were able to
900 * re-acquire the lock, so only delete from the list if the
901 * notification actually exists.
903 * Also note that this test is only valid because there's no way to
904 * *reattach* to a notifier right now. If one is added, we'll need to
905 * keep track of the notif itself and make sure they match here.
910 mutex_unlock(&match
->notify_lock
);
912 /* Userspace requests to continue the syscall. */
913 if (flags
& SECCOMP_USER_NOTIF_FLAG_CONTINUE
)
916 syscall_set_return_value(current
, current_pt_regs(),
921 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
922 const bool recheck_after_trace
)
924 u32 filter_ret
, action
;
925 struct seccomp_filter
*match
= NULL
;
927 struct seccomp_data sd_local
;
930 * Make sure that any changes to mode from another thread have
931 * been seen after TIF_SECCOMP was seen.
936 populate_seccomp_data(&sd_local
);
940 filter_ret
= seccomp_run_filters(sd
, &match
);
941 data
= filter_ret
& SECCOMP_RET_DATA
;
942 action
= filter_ret
& SECCOMP_RET_ACTION_FULL
;
945 case SECCOMP_RET_ERRNO
:
946 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
947 if (data
> MAX_ERRNO
)
949 syscall_set_return_value(current
, current_pt_regs(),
953 case SECCOMP_RET_TRAP
:
954 /* Show the handler the original registers. */
955 syscall_rollback(current
, current_pt_regs());
956 /* Let the filter pass back 16 bits of data. */
957 seccomp_send_sigsys(this_syscall
, data
);
960 case SECCOMP_RET_TRACE
:
961 /* We've been put in this state by the ptracer already. */
962 if (recheck_after_trace
)
965 /* ENOSYS these calls if there is no tracer attached. */
966 if (!ptrace_event_enabled(current
, PTRACE_EVENT_SECCOMP
)) {
967 syscall_set_return_value(current
,
973 /* Allow the BPF to provide the event message */
974 ptrace_event(PTRACE_EVENT_SECCOMP
, data
);
976 * The delivery of a fatal signal during event
977 * notification may silently skip tracer notification,
978 * which could leave us with a potentially unmodified
979 * syscall that the tracer would have liked to have
980 * changed. Since the process is about to die, we just
981 * force the syscall to be skipped and let the signal
982 * kill the process and correctly handle any tracer exit
985 if (fatal_signal_pending(current
))
987 /* Check if the tracer forced the syscall to be skipped. */
988 this_syscall
= syscall_get_nr(current
, current_pt_regs());
989 if (this_syscall
< 0)
993 * Recheck the syscall, since it may have changed. This
994 * intentionally uses a NULL struct seccomp_data to force
995 * a reload of all registers. This does not goto skip since
996 * a skip would have already been reported.
998 if (__seccomp_filter(this_syscall
, NULL
, true))
1003 case SECCOMP_RET_USER_NOTIF
:
1004 if (seccomp_do_user_notification(this_syscall
, match
, sd
))
1009 case SECCOMP_RET_LOG
:
1010 seccomp_log(this_syscall
, 0, action
, true);
1013 case SECCOMP_RET_ALLOW
:
1015 * Note that the "match" filter will always be NULL for
1016 * this action since SECCOMP_RET_ALLOW is the starting
1017 * state in seccomp_run_filters().
1021 case SECCOMP_RET_KILL_THREAD
:
1022 case SECCOMP_RET_KILL_PROCESS
:
1024 seccomp_log(this_syscall
, SIGSYS
, action
, true);
1025 /* Dump core only if this is the last remaining thread. */
1026 if (action
!= SECCOMP_RET_KILL_THREAD
||
1027 get_nr_threads(current
) == 1) {
1028 kernel_siginfo_t info
;
1030 /* Show the original registers in the dump. */
1031 syscall_rollback(current
, current_pt_regs());
1032 /* Trigger a manual coredump since do_exit skips it. */
1033 seccomp_init_siginfo(&info
, this_syscall
, data
);
1036 if (action
== SECCOMP_RET_KILL_THREAD
)
1039 do_group_exit(SIGSYS
);
1045 seccomp_log(this_syscall
, 0, action
, match
? match
->log
: false);
1049 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
1050 const bool recheck_after_trace
)
1056 int __secure_computing(const struct seccomp_data
*sd
)
1058 int mode
= current
->seccomp
.mode
;
1061 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
1062 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
1065 this_syscall
= sd
? sd
->nr
:
1066 syscall_get_nr(current
, current_pt_regs());
1069 case SECCOMP_MODE_STRICT
:
1070 __secure_computing_strict(this_syscall
); /* may call do_exit */
1072 case SECCOMP_MODE_FILTER
:
1073 return __seccomp_filter(this_syscall
, sd
, false);
1078 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1080 long prctl_get_seccomp(void)
1082 return current
->seccomp
.mode
;
1086 * seccomp_set_mode_strict: internal function for setting strict seccomp
1088 * Once current->seccomp.mode is non-zero, it may not be changed.
1090 * Returns 0 on success or -EINVAL on failure.
1092 static long seccomp_set_mode_strict(void)
1094 const unsigned long seccomp_mode
= SECCOMP_MODE_STRICT
;
1097 spin_lock_irq(¤t
->sighand
->siglock
);
1099 if (!seccomp_may_assign_mode(seccomp_mode
))
1105 seccomp_assign_mode(current
, seccomp_mode
, 0);
1109 spin_unlock_irq(¤t
->sighand
->siglock
);
1114 #ifdef CONFIG_SECCOMP_FILTER
1115 static void seccomp_notify_free(struct seccomp_filter
*filter
)
1117 kfree(filter
->notif
);
1118 filter
->notif
= NULL
;
1121 static void seccomp_notify_detach(struct seccomp_filter
*filter
)
1123 struct seccomp_knotif
*knotif
;
1128 mutex_lock(&filter
->notify_lock
);
1131 * If this file is being closed because e.g. the task who owned it
1132 * died, let's wake everyone up who was waiting on us.
1134 list_for_each_entry(knotif
, &filter
->notif
->notifications
, list
) {
1135 if (knotif
->state
== SECCOMP_NOTIFY_REPLIED
)
1138 knotif
->state
= SECCOMP_NOTIFY_REPLIED
;
1139 knotif
->error
= -ENOSYS
;
1143 * We do not need to wake up any pending addfd messages, as
1144 * the notifier will do that for us, as this just looks
1145 * like a standard reply.
1147 complete(&knotif
->ready
);
1150 seccomp_notify_free(filter
);
1151 mutex_unlock(&filter
->notify_lock
);
1154 static int seccomp_notify_release(struct inode
*inode
, struct file
*file
)
1156 struct seccomp_filter
*filter
= file
->private_data
;
1158 seccomp_notify_detach(filter
);
1159 __put_seccomp_filter(filter
);
1163 /* must be called with notif_lock held */
1164 static inline struct seccomp_knotif
*
1165 find_notification(struct seccomp_filter
*filter
, u64 id
)
1167 struct seccomp_knotif
*cur
;
1169 lockdep_assert_held(&filter
->notify_lock
);
1171 list_for_each_entry(cur
, &filter
->notif
->notifications
, list
) {
1180 static long seccomp_notify_recv(struct seccomp_filter
*filter
,
1183 struct seccomp_knotif
*knotif
= NULL
, *cur
;
1184 struct seccomp_notif unotif
;
1187 /* Verify that we're not given garbage to keep struct extensible. */
1188 ret
= check_zeroed_user(buf
, sizeof(unotif
));
1194 memset(&unotif
, 0, sizeof(unotif
));
1196 ret
= down_interruptible(&filter
->notif
->request
);
1200 mutex_lock(&filter
->notify_lock
);
1201 list_for_each_entry(cur
, &filter
->notif
->notifications
, list
) {
1202 if (cur
->state
== SECCOMP_NOTIFY_INIT
) {
1209 * If we didn't find a notification, it could be that the task was
1210 * interrupted by a fatal signal between the time we were woken and
1211 * when we were able to acquire the rw lock.
1218 unotif
.id
= knotif
->id
;
1219 unotif
.pid
= task_pid_vnr(knotif
->task
);
1220 unotif
.data
= *(knotif
->data
);
1222 knotif
->state
= SECCOMP_NOTIFY_SENT
;
1223 wake_up_poll(&filter
->wqh
, EPOLLOUT
| EPOLLWRNORM
);
1226 mutex_unlock(&filter
->notify_lock
);
1228 if (ret
== 0 && copy_to_user(buf
, &unotif
, sizeof(unotif
))) {
1232 * Userspace screwed up. To make sure that we keep this
1233 * notification alive, let's reset it back to INIT. It
1234 * may have died when we released the lock, so we need to make
1235 * sure it's still around.
1237 mutex_lock(&filter
->notify_lock
);
1238 knotif
= find_notification(filter
, unotif
.id
);
1240 knotif
->state
= SECCOMP_NOTIFY_INIT
;
1241 up(&filter
->notif
->request
);
1243 mutex_unlock(&filter
->notify_lock
);
1249 static long seccomp_notify_send(struct seccomp_filter
*filter
,
1252 struct seccomp_notif_resp resp
= {};
1253 struct seccomp_knotif
*knotif
;
1256 if (copy_from_user(&resp
, buf
, sizeof(resp
)))
1259 if (resp
.flags
& ~SECCOMP_USER_NOTIF_FLAG_CONTINUE
)
1262 if ((resp
.flags
& SECCOMP_USER_NOTIF_FLAG_CONTINUE
) &&
1263 (resp
.error
|| resp
.val
))
1266 ret
= mutex_lock_interruptible(&filter
->notify_lock
);
1270 knotif
= find_notification(filter
, resp
.id
);
1276 /* Allow exactly one reply. */
1277 if (knotif
->state
!= SECCOMP_NOTIFY_SENT
) {
1283 knotif
->state
= SECCOMP_NOTIFY_REPLIED
;
1284 knotif
->error
= resp
.error
;
1285 knotif
->val
= resp
.val
;
1286 knotif
->flags
= resp
.flags
;
1287 complete(&knotif
->ready
);
1289 mutex_unlock(&filter
->notify_lock
);
1293 static long seccomp_notify_id_valid(struct seccomp_filter
*filter
,
1296 struct seccomp_knotif
*knotif
;
1300 if (copy_from_user(&id
, buf
, sizeof(id
)))
1303 ret
= mutex_lock_interruptible(&filter
->notify_lock
);
1307 knotif
= find_notification(filter
, id
);
1308 if (knotif
&& knotif
->state
== SECCOMP_NOTIFY_SENT
)
1313 mutex_unlock(&filter
->notify_lock
);
1317 static long seccomp_notify_addfd(struct seccomp_filter
*filter
,
1318 struct seccomp_notif_addfd __user
*uaddfd
,
1321 struct seccomp_notif_addfd addfd
;
1322 struct seccomp_knotif
*knotif
;
1323 struct seccomp_kaddfd kaddfd
;
1326 BUILD_BUG_ON(sizeof(addfd
) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0
);
1327 BUILD_BUG_ON(sizeof(addfd
) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST
);
1329 if (size
< SECCOMP_NOTIFY_ADDFD_SIZE_VER0
|| size
>= PAGE_SIZE
)
1332 ret
= copy_struct_from_user(&addfd
, sizeof(addfd
), uaddfd
, size
);
1336 if (addfd
.newfd_flags
& ~O_CLOEXEC
)
1339 if (addfd
.flags
& ~SECCOMP_ADDFD_FLAG_SETFD
)
1342 if (addfd
.newfd
&& !(addfd
.flags
& SECCOMP_ADDFD_FLAG_SETFD
))
1345 kaddfd
.file
= fget(addfd
.srcfd
);
1349 kaddfd
.flags
= addfd
.newfd_flags
;
1350 kaddfd
.fd
= (addfd
.flags
& SECCOMP_ADDFD_FLAG_SETFD
) ?
1352 init_completion(&kaddfd
.completion
);
1354 ret
= mutex_lock_interruptible(&filter
->notify_lock
);
1358 knotif
= find_notification(filter
, addfd
.id
);
1365 * We do not want to allow for FD injection to occur before the
1366 * notification has been picked up by a userspace handler, or after
1367 * the notification has been replied to.
1369 if (knotif
->state
!= SECCOMP_NOTIFY_SENT
) {
1374 list_add(&kaddfd
.list
, &knotif
->addfd
);
1375 complete(&knotif
->ready
);
1376 mutex_unlock(&filter
->notify_lock
);
1378 /* Now we wait for it to be processed or be interrupted */
1379 ret
= wait_for_completion_interruptible(&kaddfd
.completion
);
1382 * We had a successful completion. The other side has already
1383 * removed us from the addfd queue, and
1384 * wait_for_completion_interruptible has a memory barrier upon
1385 * success that lets us read this value directly without
1392 mutex_lock(&filter
->notify_lock
);
1394 * Even though we were woken up by a signal and not a successful
1395 * completion, a completion may have happened in the mean time.
1397 * We need to check again if the addfd request has been handled,
1398 * and if not, we will remove it from the queue.
1400 if (list_empty(&kaddfd
.list
))
1403 list_del(&kaddfd
.list
);
1406 mutex_unlock(&filter
->notify_lock
);
1413 static long seccomp_notify_ioctl(struct file
*file
, unsigned int cmd
,
1416 struct seccomp_filter
*filter
= file
->private_data
;
1417 void __user
*buf
= (void __user
*)arg
;
1419 /* Fixed-size ioctls */
1421 case SECCOMP_IOCTL_NOTIF_RECV
:
1422 return seccomp_notify_recv(filter
, buf
);
1423 case SECCOMP_IOCTL_NOTIF_SEND
:
1424 return seccomp_notify_send(filter
, buf
);
1425 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR
:
1426 case SECCOMP_IOCTL_NOTIF_ID_VALID
:
1427 return seccomp_notify_id_valid(filter
, buf
);
1430 /* Extensible Argument ioctls */
1431 #define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1432 switch (EA_IOCTL(cmd
)) {
1433 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD
):
1434 return seccomp_notify_addfd(filter
, buf
, _IOC_SIZE(cmd
));
1440 static __poll_t
seccomp_notify_poll(struct file
*file
,
1441 struct poll_table_struct
*poll_tab
)
1443 struct seccomp_filter
*filter
= file
->private_data
;
1445 struct seccomp_knotif
*cur
;
1447 poll_wait(file
, &filter
->wqh
, poll_tab
);
1449 if (mutex_lock_interruptible(&filter
->notify_lock
) < 0)
1452 list_for_each_entry(cur
, &filter
->notif
->notifications
, list
) {
1453 if (cur
->state
== SECCOMP_NOTIFY_INIT
)
1454 ret
|= EPOLLIN
| EPOLLRDNORM
;
1455 if (cur
->state
== SECCOMP_NOTIFY_SENT
)
1456 ret
|= EPOLLOUT
| EPOLLWRNORM
;
1457 if ((ret
& EPOLLIN
) && (ret
& EPOLLOUT
))
1461 mutex_unlock(&filter
->notify_lock
);
1463 if (refcount_read(&filter
->users
) == 0)
1469 static const struct file_operations seccomp_notify_ops
= {
1470 .poll
= seccomp_notify_poll
,
1471 .release
= seccomp_notify_release
,
1472 .unlocked_ioctl
= seccomp_notify_ioctl
,
1473 .compat_ioctl
= seccomp_notify_ioctl
,
1476 static struct file
*init_listener(struct seccomp_filter
*filter
)
1480 ret
= ERR_PTR(-ENOMEM
);
1481 filter
->notif
= kzalloc(sizeof(*(filter
->notif
)), GFP_KERNEL
);
1485 sema_init(&filter
->notif
->request
, 0);
1486 filter
->notif
->next_id
= get_random_u64();
1487 INIT_LIST_HEAD(&filter
->notif
->notifications
);
1489 ret
= anon_inode_getfile("seccomp notify", &seccomp_notify_ops
,
1494 /* The file has a reference to it now */
1495 __get_seccomp_filter(filter
);
1499 seccomp_notify_free(filter
);
1505 * Does @new_child have a listener while an ancestor also has a listener?
1506 * If so, we'll want to reject this filter.
1507 * This only has to be tested for the current process, even in the TSYNC case,
1508 * because TSYNC installs @child with the same parent on all threads.
1509 * Note that @new_child is not hooked up to its parent at this point yet, so
1510 * we use current->seccomp.filter.
1512 static bool has_duplicate_listener(struct seccomp_filter
*new_child
)
1514 struct seccomp_filter
*cur
;
1516 /* must be protected against concurrent TSYNC */
1517 lockdep_assert_held(¤t
->sighand
->siglock
);
1519 if (!new_child
->notif
)
1521 for (cur
= current
->seccomp
.filter
; cur
; cur
= cur
->prev
) {
1530 * seccomp_set_mode_filter: internal function for setting seccomp filter
1531 * @flags: flags to change filter behavior
1532 * @filter: struct sock_fprog containing filter
1534 * This function may be called repeatedly to install additional filters.
1535 * Every filter successfully installed will be evaluated (in reverse order)
1536 * for each system call the task makes.
1538 * Once current->seccomp.mode is non-zero, it may not be changed.
1540 * Returns 0 on success or -EINVAL on failure.
1542 static long seccomp_set_mode_filter(unsigned int flags
,
1543 const char __user
*filter
)
1545 const unsigned long seccomp_mode
= SECCOMP_MODE_FILTER
;
1546 struct seccomp_filter
*prepared
= NULL
;
1549 struct file
*listener_f
= NULL
;
1551 /* Validate flags. */
1552 if (flags
& ~SECCOMP_FILTER_FLAG_MASK
)
1556 * In the successful case, NEW_LISTENER returns the new listener fd.
1557 * But in the failure case, TSYNC returns the thread that died. If you
1558 * combine these two flags, there's no way to tell whether something
1559 * succeeded or failed. So, let's disallow this combination if the user
1560 * has not explicitly requested no errors from TSYNC.
1562 if ((flags
& SECCOMP_FILTER_FLAG_TSYNC
) &&
1563 (flags
& SECCOMP_FILTER_FLAG_NEW_LISTENER
) &&
1564 ((flags
& SECCOMP_FILTER_FLAG_TSYNC_ESRCH
) == 0))
1567 /* Prepare the new filter before holding any locks. */
1568 prepared
= seccomp_prepare_user_filter(filter
);
1569 if (IS_ERR(prepared
))
1570 return PTR_ERR(prepared
);
1572 if (flags
& SECCOMP_FILTER_FLAG_NEW_LISTENER
) {
1573 listener
= get_unused_fd_flags(O_CLOEXEC
);
1579 listener_f
= init_listener(prepared
);
1580 if (IS_ERR(listener_f
)) {
1581 put_unused_fd(listener
);
1582 ret
= PTR_ERR(listener_f
);
1588 * Make sure we cannot change seccomp or nnp state via TSYNC
1589 * while another thread is in the middle of calling exec.
1591 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
&&
1592 mutex_lock_killable(¤t
->signal
->cred_guard_mutex
))
1595 spin_lock_irq(¤t
->sighand
->siglock
);
1597 if (!seccomp_may_assign_mode(seccomp_mode
))
1600 if (has_duplicate_listener(prepared
)) {
1605 ret
= seccomp_attach_filter(flags
, prepared
);
1608 /* Do not free the successfully attached filter. */
1611 seccomp_assign_mode(current
, seccomp_mode
, flags
);
1613 spin_unlock_irq(¤t
->sighand
->siglock
);
1614 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
1615 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
1617 if (flags
& SECCOMP_FILTER_FLAG_NEW_LISTENER
) {
1619 listener_f
->private_data
= NULL
;
1621 put_unused_fd(listener
);
1622 seccomp_notify_detach(prepared
);
1624 fd_install(listener
, listener_f
);
1629 seccomp_filter_free(prepared
);
1633 static inline long seccomp_set_mode_filter(unsigned int flags
,
1634 const char __user
*filter
)
1640 static long seccomp_get_action_avail(const char __user
*uaction
)
1644 if (copy_from_user(&action
, uaction
, sizeof(action
)))
1648 case SECCOMP_RET_KILL_PROCESS
:
1649 case SECCOMP_RET_KILL_THREAD
:
1650 case SECCOMP_RET_TRAP
:
1651 case SECCOMP_RET_ERRNO
:
1652 case SECCOMP_RET_USER_NOTIF
:
1653 case SECCOMP_RET_TRACE
:
1654 case SECCOMP_RET_LOG
:
1655 case SECCOMP_RET_ALLOW
:
1664 static long seccomp_get_notif_sizes(void __user
*usizes
)
1666 struct seccomp_notif_sizes sizes
= {
1667 .seccomp_notif
= sizeof(struct seccomp_notif
),
1668 .seccomp_notif_resp
= sizeof(struct seccomp_notif_resp
),
1669 .seccomp_data
= sizeof(struct seccomp_data
),
1672 if (copy_to_user(usizes
, &sizes
, sizeof(sizes
)))
1678 /* Common entry point for both prctl and syscall. */
1679 static long do_seccomp(unsigned int op
, unsigned int flags
,
1683 case SECCOMP_SET_MODE_STRICT
:
1684 if (flags
!= 0 || uargs
!= NULL
)
1686 return seccomp_set_mode_strict();
1687 case SECCOMP_SET_MODE_FILTER
:
1688 return seccomp_set_mode_filter(flags
, uargs
);
1689 case SECCOMP_GET_ACTION_AVAIL
:
1693 return seccomp_get_action_avail(uargs
);
1694 case SECCOMP_GET_NOTIF_SIZES
:
1698 return seccomp_get_notif_sizes(uargs
);
1704 SYSCALL_DEFINE3(seccomp
, unsigned int, op
, unsigned int, flags
,
1705 void __user
*, uargs
)
1707 return do_seccomp(op
, flags
, uargs
);
1711 * prctl_set_seccomp: configures current->seccomp.mode
1712 * @seccomp_mode: requested mode to use
1713 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1715 * Returns 0 on success or -EINVAL on failure.
1717 long prctl_set_seccomp(unsigned long seccomp_mode
, void __user
*filter
)
1722 switch (seccomp_mode
) {
1723 case SECCOMP_MODE_STRICT
:
1724 op
= SECCOMP_SET_MODE_STRICT
;
1726 * Setting strict mode through prctl always ignored filter,
1727 * so make sure it is always NULL here to pass the internal
1728 * check in do_seccomp().
1732 case SECCOMP_MODE_FILTER
:
1733 op
= SECCOMP_SET_MODE_FILTER
;
1740 /* prctl interface doesn't have flags, so they are always zero. */
1741 return do_seccomp(op
, 0, uargs
);
1744 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1745 static struct seccomp_filter
*get_nth_filter(struct task_struct
*task
,
1746 unsigned long filter_off
)
1748 struct seccomp_filter
*orig
, *filter
;
1749 unsigned long count
;
1752 * Note: this is only correct because the caller should be the (ptrace)
1753 * tracer of the task, otherwise lock_task_sighand is needed.
1755 spin_lock_irq(&task
->sighand
->siglock
);
1757 if (task
->seccomp
.mode
!= SECCOMP_MODE_FILTER
) {
1758 spin_unlock_irq(&task
->sighand
->siglock
);
1759 return ERR_PTR(-EINVAL
);
1762 orig
= task
->seccomp
.filter
;
1763 __get_seccomp_filter(orig
);
1764 spin_unlock_irq(&task
->sighand
->siglock
);
1767 for (filter
= orig
; filter
; filter
= filter
->prev
)
1770 if (filter_off
>= count
) {
1771 filter
= ERR_PTR(-ENOENT
);
1775 count
-= filter_off
;
1776 for (filter
= orig
; filter
&& count
> 1; filter
= filter
->prev
)
1779 if (WARN_ON(count
!= 1 || !filter
)) {
1780 filter
= ERR_PTR(-ENOENT
);
1784 __get_seccomp_filter(filter
);
1787 __put_seccomp_filter(orig
);
1791 long seccomp_get_filter(struct task_struct
*task
, unsigned long filter_off
,
1794 struct seccomp_filter
*filter
;
1795 struct sock_fprog_kern
*fprog
;
1798 if (!capable(CAP_SYS_ADMIN
) ||
1799 current
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
) {
1803 filter
= get_nth_filter(task
, filter_off
);
1805 return PTR_ERR(filter
);
1807 fprog
= filter
->prog
->orig_prog
;
1809 /* This must be a new non-cBPF filter, since we save
1810 * every cBPF filter's orig_prog above when
1811 * CONFIG_CHECKPOINT_RESTORE is enabled.
1821 if (copy_to_user(data
, fprog
->filter
, bpf_classic_proglen(fprog
)))
1825 __put_seccomp_filter(filter
);
1829 long seccomp_get_metadata(struct task_struct
*task
,
1830 unsigned long size
, void __user
*data
)
1833 struct seccomp_filter
*filter
;
1834 struct seccomp_metadata kmd
= {};
1836 if (!capable(CAP_SYS_ADMIN
) ||
1837 current
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
) {
1841 size
= min_t(unsigned long, size
, sizeof(kmd
));
1843 if (size
< sizeof(kmd
.filter_off
))
1846 if (copy_from_user(&kmd
.filter_off
, data
, sizeof(kmd
.filter_off
)))
1849 filter
= get_nth_filter(task
, kmd
.filter_off
);
1851 return PTR_ERR(filter
);
1854 kmd
.flags
|= SECCOMP_FILTER_FLAG_LOG
;
1857 if (copy_to_user(data
, &kmd
, size
))
1860 __put_seccomp_filter(filter
);
1865 #ifdef CONFIG_SYSCTL
1867 /* Human readable action names for friendly sysctl interaction */
1868 #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
1869 #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
1870 #define SECCOMP_RET_TRAP_NAME "trap"
1871 #define SECCOMP_RET_ERRNO_NAME "errno"
1872 #define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
1873 #define SECCOMP_RET_TRACE_NAME "trace"
1874 #define SECCOMP_RET_LOG_NAME "log"
1875 #define SECCOMP_RET_ALLOW_NAME "allow"
1877 static const char seccomp_actions_avail
[] =
1878 SECCOMP_RET_KILL_PROCESS_NAME
" "
1879 SECCOMP_RET_KILL_THREAD_NAME
" "
1880 SECCOMP_RET_TRAP_NAME
" "
1881 SECCOMP_RET_ERRNO_NAME
" "
1882 SECCOMP_RET_USER_NOTIF_NAME
" "
1883 SECCOMP_RET_TRACE_NAME
" "
1884 SECCOMP_RET_LOG_NAME
" "
1885 SECCOMP_RET_ALLOW_NAME
;
1887 struct seccomp_log_name
{
1892 static const struct seccomp_log_name seccomp_log_names
[] = {
1893 { SECCOMP_LOG_KILL_PROCESS
, SECCOMP_RET_KILL_PROCESS_NAME
},
1894 { SECCOMP_LOG_KILL_THREAD
, SECCOMP_RET_KILL_THREAD_NAME
},
1895 { SECCOMP_LOG_TRAP
, SECCOMP_RET_TRAP_NAME
},
1896 { SECCOMP_LOG_ERRNO
, SECCOMP_RET_ERRNO_NAME
},
1897 { SECCOMP_LOG_USER_NOTIF
, SECCOMP_RET_USER_NOTIF_NAME
},
1898 { SECCOMP_LOG_TRACE
, SECCOMP_RET_TRACE_NAME
},
1899 { SECCOMP_LOG_LOG
, SECCOMP_RET_LOG_NAME
},
1900 { SECCOMP_LOG_ALLOW
, SECCOMP_RET_ALLOW_NAME
},
1904 static bool seccomp_names_from_actions_logged(char *names
, size_t size
,
1908 const struct seccomp_log_name
*cur
;
1909 bool append_sep
= false;
1911 for (cur
= seccomp_log_names
; cur
->name
&& size
; cur
++) {
1914 if (!(actions_logged
& cur
->log
))
1918 ret
= strscpy(names
, sep
, size
);
1927 ret
= strscpy(names
, cur
->name
, size
);
1938 static bool seccomp_action_logged_from_name(u32
*action_logged
,
1941 const struct seccomp_log_name
*cur
;
1943 for (cur
= seccomp_log_names
; cur
->name
; cur
++) {
1944 if (!strcmp(cur
->name
, name
)) {
1945 *action_logged
= cur
->log
;
1953 static bool seccomp_actions_logged_from_names(u32
*actions_logged
, char *names
)
1957 *actions_logged
= 0;
1958 while ((name
= strsep(&names
, " ")) && *name
) {
1959 u32 action_logged
= 0;
1961 if (!seccomp_action_logged_from_name(&action_logged
, name
))
1964 *actions_logged
|= action_logged
;
1970 static int read_actions_logged(struct ctl_table
*ro_table
, void __user
*buffer
,
1971 size_t *lenp
, loff_t
*ppos
)
1973 char names
[sizeof(seccomp_actions_avail
)];
1974 struct ctl_table table
;
1976 memset(names
, 0, sizeof(names
));
1978 if (!seccomp_names_from_actions_logged(names
, sizeof(names
),
1979 seccomp_actions_logged
, " "))
1984 table
.maxlen
= sizeof(names
);
1985 return proc_dostring(&table
, 0, buffer
, lenp
, ppos
);
1988 static int write_actions_logged(struct ctl_table
*ro_table
, void __user
*buffer
,
1989 size_t *lenp
, loff_t
*ppos
, u32
*actions_logged
)
1991 char names
[sizeof(seccomp_actions_avail
)];
1992 struct ctl_table table
;
1995 if (!capable(CAP_SYS_ADMIN
))
1998 memset(names
, 0, sizeof(names
));
2002 table
.maxlen
= sizeof(names
);
2003 ret
= proc_dostring(&table
, 1, buffer
, lenp
, ppos
);
2007 if (!seccomp_actions_logged_from_names(actions_logged
, table
.data
))
2010 if (*actions_logged
& SECCOMP_LOG_ALLOW
)
2013 seccomp_actions_logged
= *actions_logged
;
2017 static void audit_actions_logged(u32 actions_logged
, u32 old_actions_logged
,
2020 char names
[sizeof(seccomp_actions_avail
)];
2021 char old_names
[sizeof(seccomp_actions_avail
)];
2022 const char *new = names
;
2023 const char *old
= old_names
;
2028 memset(names
, 0, sizeof(names
));
2029 memset(old_names
, 0, sizeof(old_names
));
2033 else if (!actions_logged
)
2035 else if (!seccomp_names_from_actions_logged(names
, sizeof(names
),
2036 actions_logged
, ","))
2039 if (!old_actions_logged
)
2041 else if (!seccomp_names_from_actions_logged(old_names
,
2043 old_actions_logged
, ","))
2046 return audit_seccomp_actions_logged(new, old
, !ret
);
2049 static int seccomp_actions_logged_handler(struct ctl_table
*ro_table
, int write
,
2050 void *buffer
, size_t *lenp
,
2056 u32 actions_logged
= 0;
2057 u32 old_actions_logged
= seccomp_actions_logged
;
2059 ret
= write_actions_logged(ro_table
, buffer
, lenp
, ppos
,
2061 audit_actions_logged(actions_logged
, old_actions_logged
, ret
);
2063 ret
= read_actions_logged(ro_table
, buffer
, lenp
, ppos
);
2068 static struct ctl_path seccomp_sysctl_path
[] = {
2069 { .procname
= "kernel", },
2070 { .procname
= "seccomp", },
2074 static struct ctl_table seccomp_sysctl_table
[] = {
2076 .procname
= "actions_avail",
2077 .data
= (void *) &seccomp_actions_avail
,
2078 .maxlen
= sizeof(seccomp_actions_avail
),
2080 .proc_handler
= proc_dostring
,
2083 .procname
= "actions_logged",
2085 .proc_handler
= seccomp_actions_logged_handler
,
2090 static int __init
seccomp_sysctl_init(void)
2092 struct ctl_table_header
*hdr
;
2094 hdr
= register_sysctl_paths(seccomp_sysctl_path
, seccomp_sysctl_table
);
2096 pr_warn("sysctl registration failed\n");
2098 kmemleak_not_leak(hdr
);
2103 device_initcall(seccomp_sysctl_init
)
2105 #endif /* CONFIG_SYSCTL */