2 * linux/kernel/seccomp.c
4 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
6 * Copyright (C) 2012 Google, Inc.
7 * Will Drewry <wad@chromium.org>
9 * This defines a simple but solid secure-computing facility.
11 * Mode 1 uses a fixed list of allowed system calls.
12 * Mode 2 allows user-defined system call filters in the form
13 * of Berkeley Packet Filters/Linux Socket Filters.
16 #include <linux/refcount.h>
17 #include <linux/audit.h>
18 #include <linux/compat.h>
19 #include <linux/coredump.h>
20 #include <linux/kmemleak.h>
21 #include <linux/sched.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/seccomp.h>
24 #include <linux/slab.h>
25 #include <linux/syscalls.h>
26 #include <linux/sysctl.h>
28 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
29 #include <asm/syscall.h>
32 #ifdef CONFIG_SECCOMP_FILTER
33 #include <linux/filter.h>
34 #include <linux/pid.h>
35 #include <linux/ptrace.h>
36 #include <linux/security.h>
37 #include <linux/tracehook.h>
38 #include <linux/uaccess.h>
41 * struct seccomp_filter - container for seccomp BPF programs
43 * @usage: reference count to manage the object lifetime.
44 * get/put helpers should be used when accessing an instance
45 * outside of a lifetime-guarded section. In general, this
46 * is only needed for handling filters shared across tasks.
47 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
48 * @prev: points to a previously installed, or inherited, filter
49 * @prog: the BPF program to evaluate
51 * seccomp_filter objects are organized in a tree linked via the @prev
52 * pointer. For any task, it appears to be a singly-linked list starting
53 * with current->seccomp.filter, the most recently attached or inherited filter.
54 * However, multiple filters may share a @prev node, by way of fork(), which
55 * results in a unidirectional tree existing in memory. This is similar to
56 * how namespaces work.
58 * seccomp_filter objects should never be modified after being attached
59 * to a task_struct (other than @usage).
61 struct seccomp_filter
{
64 struct seccomp_filter
*prev
;
65 struct bpf_prog
*prog
;
68 /* Limit any path through the tree to 256KB worth of instructions. */
69 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
72 * Endianness is explicitly ignored and left for BPF program authors to manage
73 * as per the specific architecture.
75 static void populate_seccomp_data(struct seccomp_data
*sd
)
77 struct task_struct
*task
= current
;
78 struct pt_regs
*regs
= task_pt_regs(task
);
79 unsigned long args
[6];
81 sd
->nr
= syscall_get_nr(task
, regs
);
82 sd
->arch
= syscall_get_arch();
83 syscall_get_arguments(task
, regs
, 0, 6, args
);
84 sd
->args
[0] = args
[0];
85 sd
->args
[1] = args
[1];
86 sd
->args
[2] = args
[2];
87 sd
->args
[3] = args
[3];
88 sd
->args
[4] = args
[4];
89 sd
->args
[5] = args
[5];
90 sd
->instruction_pointer
= KSTK_EIP(task
);
94 * seccomp_check_filter - verify seccomp filter code
95 * @filter: filter to verify
96 * @flen: length of filter
98 * Takes a previously checked filter (by bpf_check_classic) and
99 * redirects all filter code that loads struct sk_buff data
100 * and related data through seccomp_bpf_load. It also
101 * enforces length and alignment checking of those loads.
103 * Returns 0 if the rule set is legal or -EINVAL if not.
105 static int seccomp_check_filter(struct sock_filter
*filter
, unsigned int flen
)
108 for (pc
= 0; pc
< flen
; pc
++) {
109 struct sock_filter
*ftest
= &filter
[pc
];
110 u16 code
= ftest
->code
;
114 case BPF_LD
| BPF_W
| BPF_ABS
:
115 ftest
->code
= BPF_LDX
| BPF_W
| BPF_ABS
;
116 /* 32-bit aligned and not out of bounds. */
117 if (k
>= sizeof(struct seccomp_data
) || k
& 3)
120 case BPF_LD
| BPF_W
| BPF_LEN
:
121 ftest
->code
= BPF_LD
| BPF_IMM
;
122 ftest
->k
= sizeof(struct seccomp_data
);
124 case BPF_LDX
| BPF_W
| BPF_LEN
:
125 ftest
->code
= BPF_LDX
| BPF_IMM
;
126 ftest
->k
= sizeof(struct seccomp_data
);
128 /* Explicitly include allowed calls. */
129 case BPF_RET
| BPF_K
:
130 case BPF_RET
| BPF_A
:
131 case BPF_ALU
| BPF_ADD
| BPF_K
:
132 case BPF_ALU
| BPF_ADD
| BPF_X
:
133 case BPF_ALU
| BPF_SUB
| BPF_K
:
134 case BPF_ALU
| BPF_SUB
| BPF_X
:
135 case BPF_ALU
| BPF_MUL
| BPF_K
:
136 case BPF_ALU
| BPF_MUL
| BPF_X
:
137 case BPF_ALU
| BPF_DIV
| BPF_K
:
138 case BPF_ALU
| BPF_DIV
| BPF_X
:
139 case BPF_ALU
| BPF_AND
| BPF_K
:
140 case BPF_ALU
| BPF_AND
| BPF_X
:
141 case BPF_ALU
| BPF_OR
| BPF_K
:
142 case BPF_ALU
| BPF_OR
| BPF_X
:
143 case BPF_ALU
| BPF_XOR
| BPF_K
:
144 case BPF_ALU
| BPF_XOR
| BPF_X
:
145 case BPF_ALU
| BPF_LSH
| BPF_K
:
146 case BPF_ALU
| BPF_LSH
| BPF_X
:
147 case BPF_ALU
| BPF_RSH
| BPF_K
:
148 case BPF_ALU
| BPF_RSH
| BPF_X
:
149 case BPF_ALU
| BPF_NEG
:
150 case BPF_LD
| BPF_IMM
:
151 case BPF_LDX
| BPF_IMM
:
152 case BPF_MISC
| BPF_TAX
:
153 case BPF_MISC
| BPF_TXA
:
154 case BPF_LD
| BPF_MEM
:
155 case BPF_LDX
| BPF_MEM
:
158 case BPF_JMP
| BPF_JA
:
159 case BPF_JMP
| BPF_JEQ
| BPF_K
:
160 case BPF_JMP
| BPF_JEQ
| BPF_X
:
161 case BPF_JMP
| BPF_JGE
| BPF_K
:
162 case BPF_JMP
| BPF_JGE
| BPF_X
:
163 case BPF_JMP
| BPF_JGT
| BPF_K
:
164 case BPF_JMP
| BPF_JGT
| BPF_X
:
165 case BPF_JMP
| BPF_JSET
| BPF_K
:
166 case BPF_JMP
| BPF_JSET
| BPF_X
:
176 * seccomp_run_filters - evaluates all seccomp filters against @sd
177 * @sd: optional seccomp data to be passed to filters
178 * @match: stores struct seccomp_filter that resulted in the return value,
179 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
182 * Returns valid seccomp BPF response codes.
184 static u32
seccomp_run_filters(const struct seccomp_data
*sd
,
185 struct seccomp_filter
**match
)
187 struct seccomp_data sd_local
;
188 u32 ret
= SECCOMP_RET_ALLOW
;
189 /* Make sure cross-thread synced filter points somewhere sane. */
190 struct seccomp_filter
*f
=
191 lockless_dereference(current
->seccomp
.filter
);
193 /* Ensure unexpected behavior doesn't result in failing open. */
194 if (unlikely(WARN_ON(f
== NULL
)))
195 return SECCOMP_RET_KILL
;
198 populate_seccomp_data(&sd_local
);
203 * All filters in the list are evaluated and the lowest BPF return
204 * value always takes priority (ignoring the DATA).
206 for (; f
; f
= f
->prev
) {
207 u32 cur_ret
= BPF_PROG_RUN(f
->prog
, sd
);
209 if ((cur_ret
& SECCOMP_RET_ACTION
) < (ret
& SECCOMP_RET_ACTION
)) {
216 #endif /* CONFIG_SECCOMP_FILTER */
218 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode
)
220 assert_spin_locked(¤t
->sighand
->siglock
);
222 if (current
->seccomp
.mode
&& current
->seccomp
.mode
!= seccomp_mode
)
228 static inline void seccomp_assign_mode(struct task_struct
*task
,
229 unsigned long seccomp_mode
)
231 assert_spin_locked(&task
->sighand
->siglock
);
233 task
->seccomp
.mode
= seccomp_mode
;
235 * Make sure TIF_SECCOMP cannot be set before the mode (and
238 smp_mb__before_atomic();
239 set_tsk_thread_flag(task
, TIF_SECCOMP
);
242 #ifdef CONFIG_SECCOMP_FILTER
243 /* Returns 1 if the parent is an ancestor of the child. */
244 static int is_ancestor(struct seccomp_filter
*parent
,
245 struct seccomp_filter
*child
)
247 /* NULL is the root ancestor. */
250 for (; child
; child
= child
->prev
)
257 * seccomp_can_sync_threads: checks if all threads can be synchronized
259 * Expects sighand and cred_guard_mutex locks to be held.
261 * Returns 0 on success, -ve on error, or the pid of a thread which was
262 * either not in the correct seccomp mode or it did not have an ancestral
265 static inline pid_t
seccomp_can_sync_threads(void)
267 struct task_struct
*thread
, *caller
;
269 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
270 assert_spin_locked(¤t
->sighand
->siglock
);
272 /* Validate all threads being eligible for synchronization. */
274 for_each_thread(caller
, thread
) {
277 /* Skip current, since it is initiating the sync. */
278 if (thread
== caller
)
281 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
||
282 (thread
->seccomp
.mode
== SECCOMP_MODE_FILTER
&&
283 is_ancestor(thread
->seccomp
.filter
,
284 caller
->seccomp
.filter
)))
287 /* Return the first thread that cannot be synchronized. */
288 failed
= task_pid_vnr(thread
);
289 /* If the pid cannot be resolved, then return -ESRCH */
290 if (unlikely(WARN_ON(failed
== 0)))
299 * seccomp_sync_threads: sets all threads to use current's filter
301 * Expects sighand and cred_guard_mutex locks to be held, and for
302 * seccomp_can_sync_threads() to have returned success already
303 * without dropping the locks.
306 static inline void seccomp_sync_threads(void)
308 struct task_struct
*thread
, *caller
;
310 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
311 assert_spin_locked(¤t
->sighand
->siglock
);
313 /* Synchronize all threads. */
315 for_each_thread(caller
, thread
) {
316 /* Skip current, since it needs no changes. */
317 if (thread
== caller
)
320 /* Get a task reference for the new leaf node. */
321 get_seccomp_filter(caller
);
323 * Drop the task reference to the shared ancestor since
324 * current's path will hold a reference. (This also
325 * allows a put before the assignment.)
327 put_seccomp_filter(thread
);
328 smp_store_release(&thread
->seccomp
.filter
,
329 caller
->seccomp
.filter
);
332 * Don't let an unprivileged task work around
333 * the no_new_privs restriction by creating
334 * a thread that sets it up, enters seccomp,
337 if (task_no_new_privs(caller
))
338 task_set_no_new_privs(thread
);
341 * Opt the other thread into seccomp if needed.
342 * As threads are considered to be trust-realm
343 * equivalent (see ptrace_may_access), it is safe to
344 * allow one thread to transition the other.
346 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
)
347 seccomp_assign_mode(thread
, SECCOMP_MODE_FILTER
);
352 * seccomp_prepare_filter: Prepares a seccomp filter for use.
353 * @fprog: BPF program to install
355 * Returns filter on success or an ERR_PTR on failure.
357 static struct seccomp_filter
*seccomp_prepare_filter(struct sock_fprog
*fprog
)
359 struct seccomp_filter
*sfilter
;
361 const bool save_orig
= IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
);
363 if (fprog
->len
== 0 || fprog
->len
> BPF_MAXINSNS
)
364 return ERR_PTR(-EINVAL
);
366 BUG_ON(INT_MAX
/ fprog
->len
< sizeof(struct sock_filter
));
369 * Installing a seccomp filter requires that the task has
370 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
371 * This avoids scenarios where unprivileged tasks can affect the
372 * behavior of privileged children.
374 if (!task_no_new_privs(current
) &&
375 security_capable_noaudit(current_cred(), current_user_ns(),
377 return ERR_PTR(-EACCES
);
379 /* Allocate a new seccomp_filter */
380 sfilter
= kzalloc(sizeof(*sfilter
), GFP_KERNEL
| __GFP_NOWARN
);
382 return ERR_PTR(-ENOMEM
);
384 ret
= bpf_prog_create_from_user(&sfilter
->prog
, fprog
,
385 seccomp_check_filter
, save_orig
);
391 refcount_set(&sfilter
->usage
, 1);
397 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
398 * @user_filter: pointer to the user data containing a sock_fprog.
400 * Returns 0 on success and non-zero otherwise.
402 static struct seccomp_filter
*
403 seccomp_prepare_user_filter(const char __user
*user_filter
)
405 struct sock_fprog fprog
;
406 struct seccomp_filter
*filter
= ERR_PTR(-EFAULT
);
409 if (in_compat_syscall()) {
410 struct compat_sock_fprog fprog32
;
411 if (copy_from_user(&fprog32
, user_filter
, sizeof(fprog32
)))
413 fprog
.len
= fprog32
.len
;
414 fprog
.filter
= compat_ptr(fprog32
.filter
);
415 } else /* falls through to the if below. */
417 if (copy_from_user(&fprog
, user_filter
, sizeof(fprog
)))
419 filter
= seccomp_prepare_filter(&fprog
);
425 * seccomp_attach_filter: validate and attach filter
426 * @flags: flags to change filter behavior
427 * @filter: seccomp filter to add to the current process
429 * Caller must be holding current->sighand->siglock lock.
431 * Returns 0 on success, -ve on error.
433 static long seccomp_attach_filter(unsigned int flags
,
434 struct seccomp_filter
*filter
)
436 unsigned long total_insns
;
437 struct seccomp_filter
*walker
;
439 assert_spin_locked(¤t
->sighand
->siglock
);
441 /* Validate resulting filter length. */
442 total_insns
= filter
->prog
->len
;
443 for (walker
= current
->seccomp
.filter
; walker
; walker
= walker
->prev
)
444 total_insns
+= walker
->prog
->len
+ 4; /* 4 instr penalty */
445 if (total_insns
> MAX_INSNS_PER_PATH
)
448 /* If thread sync has been requested, check that it is possible. */
449 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
) {
452 ret
= seccomp_can_sync_threads();
457 /* Set log flag, if present. */
458 if (flags
& SECCOMP_FILTER_FLAG_LOG
)
462 * If there is an existing filter, make it the prev and don't drop its
465 filter
->prev
= current
->seccomp
.filter
;
466 current
->seccomp
.filter
= filter
;
468 /* Now that the new filter is in place, synchronize to all threads. */
469 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
470 seccomp_sync_threads();
475 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
476 void get_seccomp_filter(struct task_struct
*tsk
)
478 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
481 /* Reference count is bounded by the number of total processes. */
482 refcount_inc(&orig
->usage
);
485 static inline void seccomp_filter_free(struct seccomp_filter
*filter
)
488 bpf_prog_destroy(filter
->prog
);
493 /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
494 void put_seccomp_filter(struct task_struct
*tsk
)
496 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
497 /* Clean up single-reference branches iteratively. */
498 while (orig
&& refcount_dec_and_test(&orig
->usage
)) {
499 struct seccomp_filter
*freeme
= orig
;
501 seccomp_filter_free(freeme
);
505 static void seccomp_init_siginfo(siginfo_t
*info
, int syscall
, int reason
)
507 memset(info
, 0, sizeof(*info
));
508 info
->si_signo
= SIGSYS
;
509 info
->si_code
= SYS_SECCOMP
;
510 info
->si_call_addr
= (void __user
*)KSTK_EIP(current
);
511 info
->si_errno
= reason
;
512 info
->si_arch
= syscall_get_arch();
513 info
->si_syscall
= syscall
;
517 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
518 * @syscall: syscall number to send to userland
519 * @reason: filter-supplied reason code to send to userland (via si_errno)
521 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
523 static void seccomp_send_sigsys(int syscall
, int reason
)
526 seccomp_init_siginfo(&info
, syscall
, reason
);
527 force_sig_info(SIGSYS
, &info
, current
);
529 #endif /* CONFIG_SECCOMP_FILTER */
531 /* For use with seccomp_actions_logged */
532 #define SECCOMP_LOG_KILL (1 << 0)
533 #define SECCOMP_LOG_TRAP (1 << 2)
534 #define SECCOMP_LOG_ERRNO (1 << 3)
535 #define SECCOMP_LOG_TRACE (1 << 4)
536 #define SECCOMP_LOG_ALLOW (1 << 5)
538 static u32 seccomp_actions_logged
= SECCOMP_LOG_KILL
| SECCOMP_LOG_TRAP
|
539 SECCOMP_LOG_ERRNO
| SECCOMP_LOG_TRACE
;
541 static inline void seccomp_log(unsigned long syscall
, long signr
, u32 action
,
547 case SECCOMP_RET_ALLOW
:
549 case SECCOMP_RET_TRAP
:
550 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRAP
;
552 case SECCOMP_RET_ERRNO
:
553 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_ERRNO
;
555 case SECCOMP_RET_TRACE
:
556 log
= requested
&& seccomp_actions_logged
& SECCOMP_LOG_TRACE
;
558 case SECCOMP_RET_KILL
:
560 log
= seccomp_actions_logged
& SECCOMP_LOG_KILL
;
564 * Force an audit message to be emitted when the action is RET_KILL or
565 * the FILTER_FLAG_LOG bit was set and the action is allowed to be
566 * logged by the admin.
569 return __audit_seccomp(syscall
, signr
, action
);
572 * Let the audit subsystem decide if the action should be audited based
573 * on whether the current task itself is being audited.
575 return audit_seccomp(syscall
, signr
, action
);
579 * Secure computing mode 1 allows only read/write/exit/sigreturn.
580 * To be fully secure this must be combined with rlimit
581 * to limit the stack allocations too.
583 static const int mode1_syscalls
[] = {
584 __NR_seccomp_read
, __NR_seccomp_write
, __NR_seccomp_exit
, __NR_seccomp_sigreturn
,
585 0, /* null terminated */
588 static void __secure_computing_strict(int this_syscall
)
590 const int *syscall_whitelist
= mode1_syscalls
;
592 if (in_compat_syscall())
593 syscall_whitelist
= get_compat_mode1_syscalls();
596 if (*syscall_whitelist
== this_syscall
)
598 } while (*++syscall_whitelist
);
603 seccomp_log(this_syscall
, SIGKILL
, SECCOMP_RET_KILL
, true);
607 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
608 void secure_computing_strict(int this_syscall
)
610 int mode
= current
->seccomp
.mode
;
612 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
613 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
616 if (mode
== SECCOMP_MODE_DISABLED
)
618 else if (mode
== SECCOMP_MODE_STRICT
)
619 __secure_computing_strict(this_syscall
);
625 #ifdef CONFIG_SECCOMP_FILTER
626 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
627 const bool recheck_after_trace
)
629 u32 filter_ret
, action
;
630 struct seccomp_filter
*match
= NULL
;
634 * Make sure that any changes to mode from another thread have
635 * been seen after TIF_SECCOMP was seen.
639 filter_ret
= seccomp_run_filters(sd
, &match
);
640 data
= filter_ret
& SECCOMP_RET_DATA
;
641 action
= filter_ret
& SECCOMP_RET_ACTION
;
644 case SECCOMP_RET_ERRNO
:
645 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
646 if (data
> MAX_ERRNO
)
648 syscall_set_return_value(current
, task_pt_regs(current
),
652 case SECCOMP_RET_TRAP
:
653 /* Show the handler the original registers. */
654 syscall_rollback(current
, task_pt_regs(current
));
655 /* Let the filter pass back 16 bits of data. */
656 seccomp_send_sigsys(this_syscall
, data
);
659 case SECCOMP_RET_TRACE
:
660 /* We've been put in this state by the ptracer already. */
661 if (recheck_after_trace
)
664 /* ENOSYS these calls if there is no tracer attached. */
665 if (!ptrace_event_enabled(current
, PTRACE_EVENT_SECCOMP
)) {
666 syscall_set_return_value(current
,
667 task_pt_regs(current
),
672 /* Allow the BPF to provide the event message */
673 ptrace_event(PTRACE_EVENT_SECCOMP
, data
);
675 * The delivery of a fatal signal during event
676 * notification may silently skip tracer notification,
677 * which could leave us with a potentially unmodified
678 * syscall that the tracer would have liked to have
679 * changed. Since the process is about to die, we just
680 * force the syscall to be skipped and let the signal
681 * kill the process and correctly handle any tracer exit
684 if (fatal_signal_pending(current
))
686 /* Check if the tracer forced the syscall to be skipped. */
687 this_syscall
= syscall_get_nr(current
, task_pt_regs(current
));
688 if (this_syscall
< 0)
692 * Recheck the syscall, since it may have changed. This
693 * intentionally uses a NULL struct seccomp_data to force
694 * a reload of all registers. This does not goto skip since
695 * a skip would have already been reported.
697 if (__seccomp_filter(this_syscall
, NULL
, true))
702 case SECCOMP_RET_ALLOW
:
704 * Note that the "match" filter will always be NULL for
705 * this action since SECCOMP_RET_ALLOW is the starting
706 * state in seccomp_run_filters().
710 case SECCOMP_RET_KILL
:
712 seccomp_log(this_syscall
, SIGSYS
, action
, true);
713 /* Dump core only if this is the last remaining thread. */
714 if (get_nr_threads(current
) == 1) {
717 /* Show the original registers in the dump. */
718 syscall_rollback(current
, task_pt_regs(current
));
719 /* Trigger a manual coredump since do_exit skips it. */
720 seccomp_init_siginfo(&info
, this_syscall
, data
);
729 seccomp_log(this_syscall
, 0, action
, match
? match
->log
: false);
733 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
734 const bool recheck_after_trace
)
740 int __secure_computing(const struct seccomp_data
*sd
)
742 int mode
= current
->seccomp
.mode
;
745 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
746 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
749 this_syscall
= sd
? sd
->nr
:
750 syscall_get_nr(current
, task_pt_regs(current
));
753 case SECCOMP_MODE_STRICT
:
754 __secure_computing_strict(this_syscall
); /* may call do_exit */
756 case SECCOMP_MODE_FILTER
:
757 return __seccomp_filter(this_syscall
, sd
, false);
762 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
764 long prctl_get_seccomp(void)
766 return current
->seccomp
.mode
;
770 * seccomp_set_mode_strict: internal function for setting strict seccomp
772 * Once current->seccomp.mode is non-zero, it may not be changed.
774 * Returns 0 on success or -EINVAL on failure.
776 static long seccomp_set_mode_strict(void)
778 const unsigned long seccomp_mode
= SECCOMP_MODE_STRICT
;
781 spin_lock_irq(¤t
->sighand
->siglock
);
783 if (!seccomp_may_assign_mode(seccomp_mode
))
789 seccomp_assign_mode(current
, seccomp_mode
);
793 spin_unlock_irq(¤t
->sighand
->siglock
);
798 #ifdef CONFIG_SECCOMP_FILTER
800 * seccomp_set_mode_filter: internal function for setting seccomp filter
801 * @flags: flags to change filter behavior
802 * @filter: struct sock_fprog containing filter
804 * This function may be called repeatedly to install additional filters.
805 * Every filter successfully installed will be evaluated (in reverse order)
806 * for each system call the task makes.
808 * Once current->seccomp.mode is non-zero, it may not be changed.
810 * Returns 0 on success or -EINVAL on failure.
812 static long seccomp_set_mode_filter(unsigned int flags
,
813 const char __user
*filter
)
815 const unsigned long seccomp_mode
= SECCOMP_MODE_FILTER
;
816 struct seccomp_filter
*prepared
= NULL
;
819 /* Validate flags. */
820 if (flags
& ~SECCOMP_FILTER_FLAG_MASK
)
823 /* Prepare the new filter before holding any locks. */
824 prepared
= seccomp_prepare_user_filter(filter
);
825 if (IS_ERR(prepared
))
826 return PTR_ERR(prepared
);
829 * Make sure we cannot change seccomp or nnp state via TSYNC
830 * while another thread is in the middle of calling exec.
832 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
&&
833 mutex_lock_killable(¤t
->signal
->cred_guard_mutex
))
836 spin_lock_irq(¤t
->sighand
->siglock
);
838 if (!seccomp_may_assign_mode(seccomp_mode
))
841 ret
= seccomp_attach_filter(flags
, prepared
);
844 /* Do not free the successfully attached filter. */
847 seccomp_assign_mode(current
, seccomp_mode
);
849 spin_unlock_irq(¤t
->sighand
->siglock
);
850 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
851 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
853 seccomp_filter_free(prepared
);
857 static inline long seccomp_set_mode_filter(unsigned int flags
,
858 const char __user
*filter
)
864 static long seccomp_get_action_avail(const char __user
*uaction
)
868 if (copy_from_user(&action
, uaction
, sizeof(action
)))
872 case SECCOMP_RET_KILL
:
873 case SECCOMP_RET_TRAP
:
874 case SECCOMP_RET_ERRNO
:
875 case SECCOMP_RET_TRACE
:
876 case SECCOMP_RET_ALLOW
:
885 /* Common entry point for both prctl and syscall. */
886 static long do_seccomp(unsigned int op
, unsigned int flags
,
887 const char __user
*uargs
)
890 case SECCOMP_SET_MODE_STRICT
:
891 if (flags
!= 0 || uargs
!= NULL
)
893 return seccomp_set_mode_strict();
894 case SECCOMP_SET_MODE_FILTER
:
895 return seccomp_set_mode_filter(flags
, uargs
);
896 case SECCOMP_GET_ACTION_AVAIL
:
900 return seccomp_get_action_avail(uargs
);
906 SYSCALL_DEFINE3(seccomp
, unsigned int, op
, unsigned int, flags
,
907 const char __user
*, uargs
)
909 return do_seccomp(op
, flags
, uargs
);
913 * prctl_set_seccomp: configures current->seccomp.mode
914 * @seccomp_mode: requested mode to use
915 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
917 * Returns 0 on success or -EINVAL on failure.
919 long prctl_set_seccomp(unsigned long seccomp_mode
, char __user
*filter
)
924 switch (seccomp_mode
) {
925 case SECCOMP_MODE_STRICT
:
926 op
= SECCOMP_SET_MODE_STRICT
;
928 * Setting strict mode through prctl always ignored filter,
929 * so make sure it is always NULL here to pass the internal
930 * check in do_seccomp().
934 case SECCOMP_MODE_FILTER
:
935 op
= SECCOMP_SET_MODE_FILTER
;
942 /* prctl interface doesn't have flags, so they are always zero. */
943 return do_seccomp(op
, 0, uargs
);
946 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
947 long seccomp_get_filter(struct task_struct
*task
, unsigned long filter_off
,
950 struct seccomp_filter
*filter
;
951 struct sock_fprog_kern
*fprog
;
953 unsigned long count
= 0;
955 if (!capable(CAP_SYS_ADMIN
) ||
956 current
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
) {
960 spin_lock_irq(&task
->sighand
->siglock
);
961 if (task
->seccomp
.mode
!= SECCOMP_MODE_FILTER
) {
966 filter
= task
->seccomp
.filter
;
968 filter
= filter
->prev
;
972 if (filter_off
>= count
) {
978 filter
= task
->seccomp
.filter
;
979 while (filter
&& count
> 1) {
980 filter
= filter
->prev
;
984 if (WARN_ON(count
!= 1 || !filter
)) {
985 /* The filter tree shouldn't shrink while we're using it. */
990 fprog
= filter
->prog
->orig_prog
;
992 /* This must be a new non-cBPF filter, since we save
993 * every cBPF filter's orig_prog above when
994 * CONFIG_CHECKPOINT_RESTORE is enabled.
1004 get_seccomp_filter(task
);
1005 spin_unlock_irq(&task
->sighand
->siglock
);
1007 if (copy_to_user(data
, fprog
->filter
, bpf_classic_proglen(fprog
)))
1010 put_seccomp_filter(task
);
1014 spin_unlock_irq(&task
->sighand
->siglock
);
1019 #ifdef CONFIG_SYSCTL
1021 /* Human readable action names for friendly sysctl interaction */
1022 #define SECCOMP_RET_KILL_NAME "kill"
1023 #define SECCOMP_RET_TRAP_NAME "trap"
1024 #define SECCOMP_RET_ERRNO_NAME "errno"
1025 #define SECCOMP_RET_TRACE_NAME "trace"
1026 #define SECCOMP_RET_ALLOW_NAME "allow"
1028 static const char seccomp_actions_avail
[] = SECCOMP_RET_KILL_NAME
" "
1029 SECCOMP_RET_TRAP_NAME
" "
1030 SECCOMP_RET_ERRNO_NAME
" "
1031 SECCOMP_RET_TRACE_NAME
" "
1032 SECCOMP_RET_ALLOW_NAME
;
1034 struct seccomp_log_name
{
1039 static const struct seccomp_log_name seccomp_log_names
[] = {
1040 { SECCOMP_LOG_KILL
, SECCOMP_RET_KILL_NAME
},
1041 { SECCOMP_LOG_TRAP
, SECCOMP_RET_TRAP_NAME
},
1042 { SECCOMP_LOG_ERRNO
, SECCOMP_RET_ERRNO_NAME
},
1043 { SECCOMP_LOG_TRACE
, SECCOMP_RET_TRACE_NAME
},
1044 { SECCOMP_LOG_ALLOW
, SECCOMP_RET_ALLOW_NAME
},
1048 static bool seccomp_names_from_actions_logged(char *names
, size_t size
,
1051 const struct seccomp_log_name
*cur
;
1052 bool append_space
= false;
1054 for (cur
= seccomp_log_names
; cur
->name
&& size
; cur
++) {
1057 if (!(actions_logged
& cur
->log
))
1061 ret
= strscpy(names
, " ", size
);
1068 append_space
= true;
1070 ret
= strscpy(names
, cur
->name
, size
);
1081 static bool seccomp_action_logged_from_name(u32
*action_logged
,
1084 const struct seccomp_log_name
*cur
;
1086 for (cur
= seccomp_log_names
; cur
->name
; cur
++) {
1087 if (!strcmp(cur
->name
, name
)) {
1088 *action_logged
= cur
->log
;
1096 static bool seccomp_actions_logged_from_names(u32
*actions_logged
, char *names
)
1100 *actions_logged
= 0;
1101 while ((name
= strsep(&names
, " ")) && *name
) {
1102 u32 action_logged
= 0;
1104 if (!seccomp_action_logged_from_name(&action_logged
, name
))
1107 *actions_logged
|= action_logged
;
1113 static int seccomp_actions_logged_handler(struct ctl_table
*ro_table
, int write
,
1114 void __user
*buffer
, size_t *lenp
,
1117 char names
[sizeof(seccomp_actions_avail
)];
1118 struct ctl_table table
;
1121 if (write
&& !capable(CAP_SYS_ADMIN
))
1124 memset(names
, 0, sizeof(names
));
1127 if (!seccomp_names_from_actions_logged(names
, sizeof(names
),
1128 seccomp_actions_logged
))
1134 table
.maxlen
= sizeof(names
);
1135 ret
= proc_dostring(&table
, write
, buffer
, lenp
, ppos
);
1142 if (!seccomp_actions_logged_from_names(&actions_logged
,
1146 if (actions_logged
& SECCOMP_LOG_ALLOW
)
1149 seccomp_actions_logged
= actions_logged
;
1155 static struct ctl_path seccomp_sysctl_path
[] = {
1156 { .procname
= "kernel", },
1157 { .procname
= "seccomp", },
1161 static struct ctl_table seccomp_sysctl_table
[] = {
1163 .procname
= "actions_avail",
1164 .data
= (void *) &seccomp_actions_avail
,
1165 .maxlen
= sizeof(seccomp_actions_avail
),
1167 .proc_handler
= proc_dostring
,
1170 .procname
= "actions_logged",
1172 .proc_handler
= seccomp_actions_logged_handler
,
1177 static int __init
seccomp_sysctl_init(void)
1179 struct ctl_table_header
*hdr
;
1181 hdr
= register_sysctl_paths(seccomp_sysctl_path
, seccomp_sysctl_table
);
1183 pr_warn("seccomp: sysctl registration failed\n");
1185 kmemleak_not_leak(hdr
);
1190 device_initcall(seccomp_sysctl_init
)
1192 #endif /* CONFIG_SYSCTL */