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/atomic.h>
17 #include <linux/audit.h>
18 #include <linux/compat.h>
19 #include <linux/sched.h>
20 #include <linux/seccomp.h>
21 #include <linux/slab.h>
22 #include <linux/syscalls.h>
24 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
25 #include <asm/syscall.h>
28 #ifdef CONFIG_SECCOMP_FILTER
29 #include <linux/filter.h>
30 #include <linux/pid.h>
31 #include <linux/ptrace.h>
32 #include <linux/security.h>
33 #include <linux/tracehook.h>
34 #include <linux/uaccess.h>
37 * struct seccomp_filter - container for seccomp BPF programs
39 * @usage: reference count to manage the object lifetime.
40 * get/put helpers should be used when accessing an instance
41 * outside of a lifetime-guarded section. In general, this
42 * is only needed for handling filters shared across tasks.
43 * @prev: points to a previously installed, or inherited, filter
44 * @len: the number of instructions in the program
45 * @insnsi: the BPF program instructions to evaluate
47 * seccomp_filter objects are organized in a tree linked via the @prev
48 * pointer. For any task, it appears to be a singly-linked list starting
49 * with current->seccomp.filter, the most recently attached or inherited filter.
50 * However, multiple filters may share a @prev node, by way of fork(), which
51 * results in a unidirectional tree existing in memory. This is similar to
52 * how namespaces work.
54 * seccomp_filter objects should never be modified after being attached
55 * to a task_struct (other than @usage).
57 struct seccomp_filter
{
59 struct seccomp_filter
*prev
;
60 struct bpf_prog
*prog
;
63 /* Limit any path through the tree to 256KB worth of instructions. */
64 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
67 * Endianness is explicitly ignored and left for BPF program authors to manage
68 * as per the specific architecture.
70 static void populate_seccomp_data(struct seccomp_data
*sd
)
72 struct task_struct
*task
= current
;
73 struct pt_regs
*regs
= task_pt_regs(task
);
74 unsigned long args
[6];
76 sd
->nr
= syscall_get_nr(task
, regs
);
77 sd
->arch
= syscall_get_arch();
78 syscall_get_arguments(task
, regs
, 0, 6, args
);
79 sd
->args
[0] = args
[0];
80 sd
->args
[1] = args
[1];
81 sd
->args
[2] = args
[2];
82 sd
->args
[3] = args
[3];
83 sd
->args
[4] = args
[4];
84 sd
->args
[5] = args
[5];
85 sd
->instruction_pointer
= KSTK_EIP(task
);
89 * seccomp_check_filter - verify seccomp filter code
90 * @filter: filter to verify
91 * @flen: length of filter
93 * Takes a previously checked filter (by bpf_check_classic) and
94 * redirects all filter code that loads struct sk_buff data
95 * and related data through seccomp_bpf_load. It also
96 * enforces length and alignment checking of those loads.
98 * Returns 0 if the rule set is legal or -EINVAL if not.
100 static int seccomp_check_filter(struct sock_filter
*filter
, unsigned int flen
)
103 for (pc
= 0; pc
< flen
; pc
++) {
104 struct sock_filter
*ftest
= &filter
[pc
];
105 u16 code
= ftest
->code
;
109 case BPF_LD
| BPF_W
| BPF_ABS
:
110 ftest
->code
= BPF_LDX
| BPF_W
| BPF_ABS
;
111 /* 32-bit aligned and not out of bounds. */
112 if (k
>= sizeof(struct seccomp_data
) || k
& 3)
115 case BPF_LD
| BPF_W
| BPF_LEN
:
116 ftest
->code
= BPF_LD
| BPF_IMM
;
117 ftest
->k
= sizeof(struct seccomp_data
);
119 case BPF_LDX
| BPF_W
| BPF_LEN
:
120 ftest
->code
= BPF_LDX
| BPF_IMM
;
121 ftest
->k
= sizeof(struct seccomp_data
);
123 /* Explicitly include allowed calls. */
124 case BPF_RET
| BPF_K
:
125 case BPF_RET
| BPF_A
:
126 case BPF_ALU
| BPF_ADD
| BPF_K
:
127 case BPF_ALU
| BPF_ADD
| BPF_X
:
128 case BPF_ALU
| BPF_SUB
| BPF_K
:
129 case BPF_ALU
| BPF_SUB
| BPF_X
:
130 case BPF_ALU
| BPF_MUL
| BPF_K
:
131 case BPF_ALU
| BPF_MUL
| BPF_X
:
132 case BPF_ALU
| BPF_DIV
| BPF_K
:
133 case BPF_ALU
| BPF_DIV
| BPF_X
:
134 case BPF_ALU
| BPF_AND
| BPF_K
:
135 case BPF_ALU
| BPF_AND
| BPF_X
:
136 case BPF_ALU
| BPF_OR
| BPF_K
:
137 case BPF_ALU
| BPF_OR
| BPF_X
:
138 case BPF_ALU
| BPF_XOR
| BPF_K
:
139 case BPF_ALU
| BPF_XOR
| BPF_X
:
140 case BPF_ALU
| BPF_LSH
| BPF_K
:
141 case BPF_ALU
| BPF_LSH
| BPF_X
:
142 case BPF_ALU
| BPF_RSH
| BPF_K
:
143 case BPF_ALU
| BPF_RSH
| BPF_X
:
144 case BPF_ALU
| BPF_NEG
:
145 case BPF_LD
| BPF_IMM
:
146 case BPF_LDX
| BPF_IMM
:
147 case BPF_MISC
| BPF_TAX
:
148 case BPF_MISC
| BPF_TXA
:
149 case BPF_LD
| BPF_MEM
:
150 case BPF_LDX
| BPF_MEM
:
153 case BPF_JMP
| BPF_JA
:
154 case BPF_JMP
| BPF_JEQ
| BPF_K
:
155 case BPF_JMP
| BPF_JEQ
| BPF_X
:
156 case BPF_JMP
| BPF_JGE
| BPF_K
:
157 case BPF_JMP
| BPF_JGE
| BPF_X
:
158 case BPF_JMP
| BPF_JGT
| BPF_K
:
159 case BPF_JMP
| BPF_JGT
| BPF_X
:
160 case BPF_JMP
| BPF_JSET
| BPF_K
:
161 case BPF_JMP
| BPF_JSET
| BPF_X
:
171 * seccomp_run_filters - evaluates all seccomp filters against @syscall
172 * @syscall: number of the current system call
174 * Returns valid seccomp BPF response codes.
176 static u32
seccomp_run_filters(const struct seccomp_data
*sd
)
178 struct seccomp_data sd_local
;
179 u32 ret
= SECCOMP_RET_ALLOW
;
180 /* Make sure cross-thread synced filter points somewhere sane. */
181 struct seccomp_filter
*f
=
182 lockless_dereference(current
->seccomp
.filter
);
184 /* Ensure unexpected behavior doesn't result in failing open. */
185 if (unlikely(WARN_ON(f
== NULL
)))
186 return SECCOMP_RET_KILL
;
189 populate_seccomp_data(&sd_local
);
194 * All filters in the list are evaluated and the lowest BPF return
195 * value always takes priority (ignoring the DATA).
197 for (; f
; f
= f
->prev
) {
198 u32 cur_ret
= BPF_PROG_RUN(f
->prog
, (void *)sd
);
200 if ((cur_ret
& SECCOMP_RET_ACTION
) < (ret
& SECCOMP_RET_ACTION
))
205 #endif /* CONFIG_SECCOMP_FILTER */
207 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode
)
209 assert_spin_locked(¤t
->sighand
->siglock
);
211 if (current
->seccomp
.mode
&& current
->seccomp
.mode
!= seccomp_mode
)
217 static inline void seccomp_assign_mode(struct task_struct
*task
,
218 unsigned long seccomp_mode
)
220 assert_spin_locked(&task
->sighand
->siglock
);
222 task
->seccomp
.mode
= seccomp_mode
;
224 * Make sure TIF_SECCOMP cannot be set before the mode (and
227 smp_mb__before_atomic();
228 set_tsk_thread_flag(task
, TIF_SECCOMP
);
231 #ifdef CONFIG_SECCOMP_FILTER
232 /* Returns 1 if the parent is an ancestor of the child. */
233 static int is_ancestor(struct seccomp_filter
*parent
,
234 struct seccomp_filter
*child
)
236 /* NULL is the root ancestor. */
239 for (; child
; child
= child
->prev
)
246 * seccomp_can_sync_threads: checks if all threads can be synchronized
248 * Expects sighand and cred_guard_mutex locks to be held.
250 * Returns 0 on success, -ve on error, or the pid of a thread which was
251 * either not in the correct seccomp mode or it did not have an ancestral
254 static inline pid_t
seccomp_can_sync_threads(void)
256 struct task_struct
*thread
, *caller
;
258 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
259 assert_spin_locked(¤t
->sighand
->siglock
);
261 /* Validate all threads being eligible for synchronization. */
263 for_each_thread(caller
, thread
) {
266 /* Skip current, since it is initiating the sync. */
267 if (thread
== caller
)
270 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
||
271 (thread
->seccomp
.mode
== SECCOMP_MODE_FILTER
&&
272 is_ancestor(thread
->seccomp
.filter
,
273 caller
->seccomp
.filter
)))
276 /* Return the first thread that cannot be synchronized. */
277 failed
= task_pid_vnr(thread
);
278 /* If the pid cannot be resolved, then return -ESRCH */
279 if (unlikely(WARN_ON(failed
== 0)))
288 * seccomp_sync_threads: sets all threads to use current's filter
290 * Expects sighand and cred_guard_mutex locks to be held, and for
291 * seccomp_can_sync_threads() to have returned success already
292 * without dropping the locks.
295 static inline void seccomp_sync_threads(void)
297 struct task_struct
*thread
, *caller
;
299 BUG_ON(!mutex_is_locked(¤t
->signal
->cred_guard_mutex
));
300 assert_spin_locked(¤t
->sighand
->siglock
);
302 /* Synchronize all threads. */
304 for_each_thread(caller
, thread
) {
305 /* Skip current, since it needs no changes. */
306 if (thread
== caller
)
309 /* Get a task reference for the new leaf node. */
310 get_seccomp_filter(caller
);
312 * Drop the task reference to the shared ancestor since
313 * current's path will hold a reference. (This also
314 * allows a put before the assignment.)
316 put_seccomp_filter(thread
);
317 smp_store_release(&thread
->seccomp
.filter
,
318 caller
->seccomp
.filter
);
321 * Don't let an unprivileged task work around
322 * the no_new_privs restriction by creating
323 * a thread that sets it up, enters seccomp,
326 if (task_no_new_privs(caller
))
327 task_set_no_new_privs(thread
);
330 * Opt the other thread into seccomp if needed.
331 * As threads are considered to be trust-realm
332 * equivalent (see ptrace_may_access), it is safe to
333 * allow one thread to transition the other.
335 if (thread
->seccomp
.mode
== SECCOMP_MODE_DISABLED
)
336 seccomp_assign_mode(thread
, SECCOMP_MODE_FILTER
);
341 * seccomp_prepare_filter: Prepares a seccomp filter for use.
342 * @fprog: BPF program to install
344 * Returns filter on success or an ERR_PTR on failure.
346 static struct seccomp_filter
*seccomp_prepare_filter(struct sock_fprog
*fprog
)
348 struct seccomp_filter
*sfilter
;
350 const bool save_orig
= IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
);
352 if (fprog
->len
== 0 || fprog
->len
> BPF_MAXINSNS
)
353 return ERR_PTR(-EINVAL
);
355 BUG_ON(INT_MAX
/ fprog
->len
< sizeof(struct sock_filter
));
358 * Installing a seccomp filter requires that the task has
359 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
360 * This avoids scenarios where unprivileged tasks can affect the
361 * behavior of privileged children.
363 if (!task_no_new_privs(current
) &&
364 security_capable_noaudit(current_cred(), current_user_ns(),
366 return ERR_PTR(-EACCES
);
368 /* Allocate a new seccomp_filter */
369 sfilter
= kzalloc(sizeof(*sfilter
), GFP_KERNEL
| __GFP_NOWARN
);
371 return ERR_PTR(-ENOMEM
);
373 ret
= bpf_prog_create_from_user(&sfilter
->prog
, fprog
,
374 seccomp_check_filter
, save_orig
);
380 atomic_set(&sfilter
->usage
, 1);
386 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
387 * @user_filter: pointer to the user data containing a sock_fprog.
389 * Returns 0 on success and non-zero otherwise.
391 static struct seccomp_filter
*
392 seccomp_prepare_user_filter(const char __user
*user_filter
)
394 struct sock_fprog fprog
;
395 struct seccomp_filter
*filter
= ERR_PTR(-EFAULT
);
398 if (in_compat_syscall()) {
399 struct compat_sock_fprog fprog32
;
400 if (copy_from_user(&fprog32
, user_filter
, sizeof(fprog32
)))
402 fprog
.len
= fprog32
.len
;
403 fprog
.filter
= compat_ptr(fprog32
.filter
);
404 } else /* falls through to the if below. */
406 if (copy_from_user(&fprog
, user_filter
, sizeof(fprog
)))
408 filter
= seccomp_prepare_filter(&fprog
);
414 * seccomp_attach_filter: validate and attach filter
415 * @flags: flags to change filter behavior
416 * @filter: seccomp filter to add to the current process
418 * Caller must be holding current->sighand->siglock lock.
420 * Returns 0 on success, -ve on error.
422 static long seccomp_attach_filter(unsigned int flags
,
423 struct seccomp_filter
*filter
)
425 unsigned long total_insns
;
426 struct seccomp_filter
*walker
;
428 assert_spin_locked(¤t
->sighand
->siglock
);
430 /* Validate resulting filter length. */
431 total_insns
= filter
->prog
->len
;
432 for (walker
= current
->seccomp
.filter
; walker
; walker
= walker
->prev
)
433 total_insns
+= walker
->prog
->len
+ 4; /* 4 instr penalty */
434 if (total_insns
> MAX_INSNS_PER_PATH
)
437 /* If thread sync has been requested, check that it is possible. */
438 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
) {
441 ret
= seccomp_can_sync_threads();
447 * If there is an existing filter, make it the prev and don't drop its
450 filter
->prev
= current
->seccomp
.filter
;
451 current
->seccomp
.filter
= filter
;
453 /* Now that the new filter is in place, synchronize to all threads. */
454 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
455 seccomp_sync_threads();
460 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
461 void get_seccomp_filter(struct task_struct
*tsk
)
463 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
466 /* Reference count is bounded by the number of total processes. */
467 atomic_inc(&orig
->usage
);
470 static inline void seccomp_filter_free(struct seccomp_filter
*filter
)
473 bpf_prog_destroy(filter
->prog
);
478 /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
479 void put_seccomp_filter(struct task_struct
*tsk
)
481 struct seccomp_filter
*orig
= tsk
->seccomp
.filter
;
482 /* Clean up single-reference branches iteratively. */
483 while (orig
&& atomic_dec_and_test(&orig
->usage
)) {
484 struct seccomp_filter
*freeme
= orig
;
486 seccomp_filter_free(freeme
);
491 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
492 * @syscall: syscall number to send to userland
493 * @reason: filter-supplied reason code to send to userland (via si_errno)
495 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
497 static void seccomp_send_sigsys(int syscall
, int reason
)
500 memset(&info
, 0, sizeof(info
));
501 info
.si_signo
= SIGSYS
;
502 info
.si_code
= SYS_SECCOMP
;
503 info
.si_call_addr
= (void __user
*)KSTK_EIP(current
);
504 info
.si_errno
= reason
;
505 info
.si_arch
= syscall_get_arch();
506 info
.si_syscall
= syscall
;
507 force_sig_info(SIGSYS
, &info
, current
);
509 #endif /* CONFIG_SECCOMP_FILTER */
512 * Secure computing mode 1 allows only read/write/exit/sigreturn.
513 * To be fully secure this must be combined with rlimit
514 * to limit the stack allocations too.
516 static const int mode1_syscalls
[] = {
517 __NR_seccomp_read
, __NR_seccomp_write
, __NR_seccomp_exit
, __NR_seccomp_sigreturn
,
518 0, /* null terminated */
521 static void __secure_computing_strict(int this_syscall
)
523 const int *syscall_whitelist
= mode1_syscalls
;
525 if (in_compat_syscall())
526 syscall_whitelist
= get_compat_mode1_syscalls();
529 if (*syscall_whitelist
== this_syscall
)
531 } while (*++syscall_whitelist
);
536 audit_seccomp(this_syscall
, SIGKILL
, SECCOMP_RET_KILL
);
540 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
541 void secure_computing_strict(int this_syscall
)
543 int mode
= current
->seccomp
.mode
;
545 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
546 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
549 if (mode
== SECCOMP_MODE_DISABLED
)
551 else if (mode
== SECCOMP_MODE_STRICT
)
552 __secure_computing_strict(this_syscall
);
558 #ifdef CONFIG_SECCOMP_FILTER
559 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
560 const bool recheck_after_trace
)
562 u32 filter_ret
, action
;
566 * Make sure that any changes to mode from another thread have
567 * been seen after TIF_SECCOMP was seen.
571 filter_ret
= seccomp_run_filters(sd
);
572 data
= filter_ret
& SECCOMP_RET_DATA
;
573 action
= filter_ret
& SECCOMP_RET_ACTION
;
576 case SECCOMP_RET_ERRNO
:
577 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
578 if (data
> MAX_ERRNO
)
580 syscall_set_return_value(current
, task_pt_regs(current
),
584 case SECCOMP_RET_TRAP
:
585 /* Show the handler the original registers. */
586 syscall_rollback(current
, task_pt_regs(current
));
587 /* Let the filter pass back 16 bits of data. */
588 seccomp_send_sigsys(this_syscall
, data
);
591 case SECCOMP_RET_TRACE
:
592 /* We've been put in this state by the ptracer already. */
593 if (recheck_after_trace
)
596 /* ENOSYS these calls if there is no tracer attached. */
597 if (!ptrace_event_enabled(current
, PTRACE_EVENT_SECCOMP
)) {
598 syscall_set_return_value(current
,
599 task_pt_regs(current
),
604 /* Allow the BPF to provide the event message */
605 ptrace_event(PTRACE_EVENT_SECCOMP
, data
);
607 * The delivery of a fatal signal during event
608 * notification may silently skip tracer notification,
609 * which could leave us with a potentially unmodified
610 * syscall that the tracer would have liked to have
611 * changed. Since the process is about to die, we just
612 * force the syscall to be skipped and let the signal
613 * kill the process and correctly handle any tracer exit
616 if (fatal_signal_pending(current
))
618 /* Check if the tracer forced the syscall to be skipped. */
619 this_syscall
= syscall_get_nr(current
, task_pt_regs(current
));
620 if (this_syscall
< 0)
624 * Recheck the syscall, since it may have changed. This
625 * intentionally uses a NULL struct seccomp_data to force
626 * a reload of all registers. This does not goto skip since
627 * a skip would have already been reported.
629 if (__seccomp_filter(this_syscall
, NULL
, true))
634 case SECCOMP_RET_ALLOW
:
637 case SECCOMP_RET_KILL
:
639 audit_seccomp(this_syscall
, SIGSYS
, action
);
646 audit_seccomp(this_syscall
, 0, action
);
650 static int __seccomp_filter(int this_syscall
, const struct seccomp_data
*sd
,
651 const bool recheck_after_trace
)
657 int __secure_computing(const struct seccomp_data
*sd
)
659 int mode
= current
->seccomp
.mode
;
662 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE
) &&
663 unlikely(current
->ptrace
& PT_SUSPEND_SECCOMP
))
666 this_syscall
= sd
? sd
->nr
:
667 syscall_get_nr(current
, task_pt_regs(current
));
670 case SECCOMP_MODE_STRICT
:
671 __secure_computing_strict(this_syscall
); /* may call do_exit */
673 case SECCOMP_MODE_FILTER
:
674 return __seccomp_filter(this_syscall
, sd
, false);
679 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
681 long prctl_get_seccomp(void)
683 return current
->seccomp
.mode
;
687 * seccomp_set_mode_strict: internal function for setting strict seccomp
689 * Once current->seccomp.mode is non-zero, it may not be changed.
691 * Returns 0 on success or -EINVAL on failure.
693 static long seccomp_set_mode_strict(void)
695 const unsigned long seccomp_mode
= SECCOMP_MODE_STRICT
;
698 spin_lock_irq(¤t
->sighand
->siglock
);
700 if (!seccomp_may_assign_mode(seccomp_mode
))
706 seccomp_assign_mode(current
, seccomp_mode
);
710 spin_unlock_irq(¤t
->sighand
->siglock
);
715 #ifdef CONFIG_SECCOMP_FILTER
717 * seccomp_set_mode_filter: internal function for setting seccomp filter
718 * @flags: flags to change filter behavior
719 * @filter: struct sock_fprog containing filter
721 * This function may be called repeatedly to install additional filters.
722 * Every filter successfully installed will be evaluated (in reverse order)
723 * for each system call the task makes.
725 * Once current->seccomp.mode is non-zero, it may not be changed.
727 * Returns 0 on success or -EINVAL on failure.
729 static long seccomp_set_mode_filter(unsigned int flags
,
730 const char __user
*filter
)
732 const unsigned long seccomp_mode
= SECCOMP_MODE_FILTER
;
733 struct seccomp_filter
*prepared
= NULL
;
736 /* Validate flags. */
737 if (flags
& ~SECCOMP_FILTER_FLAG_MASK
)
740 /* Prepare the new filter before holding any locks. */
741 prepared
= seccomp_prepare_user_filter(filter
);
742 if (IS_ERR(prepared
))
743 return PTR_ERR(prepared
);
746 * Make sure we cannot change seccomp or nnp state via TSYNC
747 * while another thread is in the middle of calling exec.
749 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
&&
750 mutex_lock_killable(¤t
->signal
->cred_guard_mutex
))
753 spin_lock_irq(¤t
->sighand
->siglock
);
755 if (!seccomp_may_assign_mode(seccomp_mode
))
758 ret
= seccomp_attach_filter(flags
, prepared
);
761 /* Do not free the successfully attached filter. */
764 seccomp_assign_mode(current
, seccomp_mode
);
766 spin_unlock_irq(¤t
->sighand
->siglock
);
767 if (flags
& SECCOMP_FILTER_FLAG_TSYNC
)
768 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
770 seccomp_filter_free(prepared
);
774 static inline long seccomp_set_mode_filter(unsigned int flags
,
775 const char __user
*filter
)
781 /* Common entry point for both prctl and syscall. */
782 static long do_seccomp(unsigned int op
, unsigned int flags
,
783 const char __user
*uargs
)
786 case SECCOMP_SET_MODE_STRICT
:
787 if (flags
!= 0 || uargs
!= NULL
)
789 return seccomp_set_mode_strict();
790 case SECCOMP_SET_MODE_FILTER
:
791 return seccomp_set_mode_filter(flags
, uargs
);
797 SYSCALL_DEFINE3(seccomp
, unsigned int, op
, unsigned int, flags
,
798 const char __user
*, uargs
)
800 return do_seccomp(op
, flags
, uargs
);
804 * prctl_set_seccomp: configures current->seccomp.mode
805 * @seccomp_mode: requested mode to use
806 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
808 * Returns 0 on success or -EINVAL on failure.
810 long prctl_set_seccomp(unsigned long seccomp_mode
, char __user
*filter
)
815 switch (seccomp_mode
) {
816 case SECCOMP_MODE_STRICT
:
817 op
= SECCOMP_SET_MODE_STRICT
;
819 * Setting strict mode through prctl always ignored filter,
820 * so make sure it is always NULL here to pass the internal
821 * check in do_seccomp().
825 case SECCOMP_MODE_FILTER
:
826 op
= SECCOMP_SET_MODE_FILTER
;
833 /* prctl interface doesn't have flags, so they are always zero. */
834 return do_seccomp(op
, 0, uargs
);
837 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
838 long seccomp_get_filter(struct task_struct
*task
, unsigned long filter_off
,
841 struct seccomp_filter
*filter
;
842 struct sock_fprog_kern
*fprog
;
844 unsigned long count
= 0;
846 if (!capable(CAP_SYS_ADMIN
) ||
847 current
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
) {
851 spin_lock_irq(&task
->sighand
->siglock
);
852 if (task
->seccomp
.mode
!= SECCOMP_MODE_FILTER
) {
857 filter
= task
->seccomp
.filter
;
859 filter
= filter
->prev
;
863 if (filter_off
>= count
) {
869 filter
= task
->seccomp
.filter
;
870 while (filter
&& count
> 1) {
871 filter
= filter
->prev
;
875 if (WARN_ON(count
!= 1 || !filter
)) {
876 /* The filter tree shouldn't shrink while we're using it. */
881 fprog
= filter
->prog
->orig_prog
;
883 /* This must be a new non-cBPF filter, since we save
884 * every cBPF filter's orig_prog above when
885 * CONFIG_CHECKPOINT_RESTORE is enabled.
895 get_seccomp_filter(task
);
896 spin_unlock_irq(&task
->sighand
->siglock
);
898 if (copy_to_user(data
, fprog
->filter
, bpf_classic_proglen(fprog
)))
901 put_seccomp_filter(task
);
905 spin_unlock_irq(&task
->sighand
->siglock
);