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(struct seccomp_data *sd)
178 struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
179 struct seccomp_data sd_local;
180 u32 ret = SECCOMP_RET_ALLOW;
182 /* Ensure unexpected behavior doesn't result in failing open. */
183 if (unlikely(WARN_ON(f == NULL)))
184 return SECCOMP_RET_KILL;
186 /* Make sure cross-thread synced filter points somewhere sane. */
187 smp_read_barrier_depends();
190 populate_seccomp_data(&sd_local);
195 * All filters in the list are evaluated and the lowest BPF return
196 * value always takes priority (ignoring the DATA).
198 for (; f; f = f->prev) {
199 u32 cur_ret = BPF_PROG_RUN(f->prog, (void *)sd);
201 if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
206 #endif /* CONFIG_SECCOMP_FILTER */
208 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
210 assert_spin_locked(¤t->sighand->siglock);
212 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
218 static inline void seccomp_assign_mode(struct task_struct *task,
219 unsigned long seccomp_mode)
221 assert_spin_locked(&task->sighand->siglock);
223 task->seccomp.mode = seccomp_mode;
225 * Make sure TIF_SECCOMP cannot be set before the mode (and
228 smp_mb__before_atomic();
229 set_tsk_thread_flag(task, TIF_SECCOMP);
232 #ifdef CONFIG_SECCOMP_FILTER
233 /* Returns 1 if the parent is an ancestor of the child. */
234 static int is_ancestor(struct seccomp_filter *parent,
235 struct seccomp_filter *child)
237 /* NULL is the root ancestor. */
240 for (; child; child = child->prev)
247 * seccomp_can_sync_threads: checks if all threads can be synchronized
249 * Expects sighand and cred_guard_mutex locks to be held.
251 * Returns 0 on success, -ve on error, or the pid of a thread which was
252 * either not in the correct seccomp mode or it did not have an ancestral
255 static inline pid_t seccomp_can_sync_threads(void)
257 struct task_struct *thread, *caller;
259 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
260 assert_spin_locked(¤t->sighand->siglock);
262 /* Validate all threads being eligible for synchronization. */
264 for_each_thread(caller, thread) {
267 /* Skip current, since it is initiating the sync. */
268 if (thread == caller)
271 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
272 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
273 is_ancestor(thread->seccomp.filter,
274 caller->seccomp.filter)))
277 /* Return the first thread that cannot be synchronized. */
278 failed = task_pid_vnr(thread);
279 /* If the pid cannot be resolved, then return -ESRCH */
280 if (unlikely(WARN_ON(failed == 0)))
289 * seccomp_sync_threads: sets all threads to use current's filter
291 * Expects sighand and cred_guard_mutex locks to be held, and for
292 * seccomp_can_sync_threads() to have returned success already
293 * without dropping the locks.
296 static inline void seccomp_sync_threads(void)
298 struct task_struct *thread, *caller;
300 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
301 assert_spin_locked(¤t->sighand->siglock);
303 /* Synchronize all threads. */
305 for_each_thread(caller, thread) {
306 /* Skip current, since it needs no changes. */
307 if (thread == caller)
310 /* Get a task reference for the new leaf node. */
311 get_seccomp_filter(caller);
313 * Drop the task reference to the shared ancestor since
314 * current's path will hold a reference. (This also
315 * allows a put before the assignment.)
317 put_seccomp_filter(thread);
318 smp_store_release(&thread->seccomp.filter,
319 caller->seccomp.filter);
321 * Opt the other thread into seccomp if needed.
322 * As threads are considered to be trust-realm
323 * equivalent (see ptrace_may_access), it is safe to
324 * allow one thread to transition the other.
326 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) {
328 * Don't let an unprivileged task work around
329 * the no_new_privs restriction by creating
330 * a thread that sets it up, enters seccomp,
333 if (task_no_new_privs(caller))
334 task_set_no_new_privs(thread);
336 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER);
342 * seccomp_prepare_filter: Prepares a seccomp filter for use.
343 * @fprog: BPF program to install
345 * Returns filter on success or an ERR_PTR on failure.
347 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
349 struct seccomp_filter *filter;
350 unsigned long fp_size;
351 struct sock_filter *fp;
355 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
356 return ERR_PTR(-EINVAL);
357 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
358 fp_size = fprog->len * sizeof(struct sock_filter);
361 * Installing a seccomp filter requires that the task has
362 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
363 * This avoids scenarios where unprivileged tasks can affect the
364 * behavior of privileged children.
366 if (!task_no_new_privs(current) &&
367 security_capable_noaudit(current_cred(), current_user_ns(),
369 return ERR_PTR(-EACCES);
371 fp = kzalloc(fp_size, GFP_KERNEL|__GFP_NOWARN);
373 return ERR_PTR(-ENOMEM);
375 /* Copy the instructions from fprog. */
377 if (copy_from_user(fp, fprog->filter, fp_size))
380 /* Check and rewrite the fprog via the skb checker */
381 ret = bpf_check_classic(fp, fprog->len);
385 /* Check and rewrite the fprog for seccomp use */
386 ret = seccomp_check_filter(fp, fprog->len);
390 /* Convert 'sock_filter' insns to 'bpf_insn' insns */
391 ret = bpf_convert_filter(fp, fprog->len, NULL, &new_len);
395 /* Allocate a new seccomp_filter */
397 filter = kzalloc(sizeof(struct seccomp_filter),
398 GFP_KERNEL|__GFP_NOWARN);
402 filter->prog = bpf_prog_alloc(bpf_prog_size(new_len), __GFP_NOWARN);
406 ret = bpf_convert_filter(fp, fprog->len, filter->prog->insnsi, &new_len);
408 goto free_filter_prog;
411 atomic_set(&filter->usage, 1);
412 filter->prog->len = new_len;
414 bpf_prog_select_runtime(filter->prog);
419 __bpf_prog_free(filter->prog);
428 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
429 * @user_filter: pointer to the user data containing a sock_fprog.
431 * Returns 0 on success and non-zero otherwise.
433 static struct seccomp_filter *
434 seccomp_prepare_user_filter(const char __user *user_filter)
436 struct sock_fprog fprog;
437 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
440 if (is_compat_task()) {
441 struct compat_sock_fprog fprog32;
442 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
444 fprog.len = fprog32.len;
445 fprog.filter = compat_ptr(fprog32.filter);
446 } else /* falls through to the if below. */
448 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
450 filter = seccomp_prepare_filter(&fprog);
456 * seccomp_attach_filter: validate and attach filter
457 * @flags: flags to change filter behavior
458 * @filter: seccomp filter to add to the current process
460 * Caller must be holding current->sighand->siglock lock.
462 * Returns 0 on success, -ve on error.
464 static long seccomp_attach_filter(unsigned int flags,
465 struct seccomp_filter *filter)
467 unsigned long total_insns;
468 struct seccomp_filter *walker;
470 assert_spin_locked(¤t->sighand->siglock);
472 /* Validate resulting filter length. */
473 total_insns = filter->prog->len;
474 for (walker = current->seccomp.filter; walker; walker = walker->prev)
475 total_insns += walker->prog->len + 4; /* 4 instr penalty */
476 if (total_insns > MAX_INSNS_PER_PATH)
479 /* If thread sync has been requested, check that it is possible. */
480 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
483 ret = seccomp_can_sync_threads();
489 * If there is an existing filter, make it the prev and don't drop its
492 filter->prev = current->seccomp.filter;
493 current->seccomp.filter = filter;
495 /* Now that the new filter is in place, synchronize to all threads. */
496 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
497 seccomp_sync_threads();
502 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
503 void get_seccomp_filter(struct task_struct *tsk)
505 struct seccomp_filter *orig = tsk->seccomp.filter;
508 /* Reference count is bounded by the number of total processes. */
509 atomic_inc(&orig->usage);
512 static inline void seccomp_filter_free(struct seccomp_filter *filter)
515 bpf_prog_free(filter->prog);
520 /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
521 void put_seccomp_filter(struct task_struct *tsk)
523 struct seccomp_filter *orig = tsk->seccomp.filter;
524 /* Clean up single-reference branches iteratively. */
525 while (orig && atomic_dec_and_test(&orig->usage)) {
526 struct seccomp_filter *freeme = orig;
528 seccomp_filter_free(freeme);
533 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
534 * @syscall: syscall number to send to userland
535 * @reason: filter-supplied reason code to send to userland (via si_errno)
537 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
539 static void seccomp_send_sigsys(int syscall, int reason)
542 memset(&info, 0, sizeof(info));
543 info.si_signo = SIGSYS;
544 info.si_code = SYS_SECCOMP;
545 info.si_call_addr = (void __user *)KSTK_EIP(current);
546 info.si_errno = reason;
547 info.si_arch = syscall_get_arch();
548 info.si_syscall = syscall;
549 force_sig_info(SIGSYS, &info, current);
551 #endif /* CONFIG_SECCOMP_FILTER */
554 * Secure computing mode 1 allows only read/write/exit/sigreturn.
555 * To be fully secure this must be combined with rlimit
556 * to limit the stack allocations too.
558 static int mode1_syscalls[] = {
559 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
560 0, /* null terminated */
564 static int mode1_syscalls_32[] = {
565 __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
566 0, /* null terminated */
570 static void __secure_computing_strict(int this_syscall)
572 int *syscall_whitelist = mode1_syscalls;
574 if (is_compat_task())
575 syscall_whitelist = mode1_syscalls_32;
578 if (*syscall_whitelist == this_syscall)
580 } while (*++syscall_whitelist);
585 audit_seccomp(this_syscall, SIGKILL, SECCOMP_RET_KILL);
589 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
590 void secure_computing_strict(int this_syscall)
592 int mode = current->seccomp.mode;
596 else if (mode == SECCOMP_MODE_STRICT)
597 __secure_computing_strict(this_syscall);
602 int __secure_computing(void)
604 u32 phase1_result = seccomp_phase1(NULL);
606 if (likely(phase1_result == SECCOMP_PHASE1_OK))
608 else if (likely(phase1_result == SECCOMP_PHASE1_SKIP))
611 return seccomp_phase2(phase1_result);
614 #ifdef CONFIG_SECCOMP_FILTER
615 static u32 __seccomp_phase1_filter(int this_syscall, struct seccomp_data *sd)
617 u32 filter_ret, action;
621 * Make sure that any changes to mode from another thread have
622 * been seen after TIF_SECCOMP was seen.
626 filter_ret = seccomp_run_filters(sd);
627 data = filter_ret & SECCOMP_RET_DATA;
628 action = filter_ret & SECCOMP_RET_ACTION;
631 case SECCOMP_RET_ERRNO:
632 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
633 if (data > MAX_ERRNO)
635 syscall_set_return_value(current, task_pt_regs(current),
639 case SECCOMP_RET_TRAP:
640 /* Show the handler the original registers. */
641 syscall_rollback(current, task_pt_regs(current));
642 /* Let the filter pass back 16 bits of data. */
643 seccomp_send_sigsys(this_syscall, data);
646 case SECCOMP_RET_TRACE:
647 return filter_ret; /* Save the rest for phase 2. */
649 case SECCOMP_RET_ALLOW:
650 return SECCOMP_PHASE1_OK;
652 case SECCOMP_RET_KILL:
654 audit_seccomp(this_syscall, SIGSYS, action);
661 audit_seccomp(this_syscall, 0, action);
662 return SECCOMP_PHASE1_SKIP;
667 * seccomp_phase1() - run fast path seccomp checks on the current syscall
668 * @arg sd: The seccomp_data or NULL
670 * This only reads pt_regs via the syscall_xyz helpers. The only change
671 * it will make to pt_regs is via syscall_set_return_value, and it will
672 * only do that if it returns SECCOMP_PHASE1_SKIP.
674 * If sd is provided, it will not read pt_regs at all.
676 * It may also call do_exit or force a signal; these actions must be
679 * If it returns SECCOMP_PHASE1_OK, the syscall passes checks and should
680 * be processed normally.
682 * If it returns SECCOMP_PHASE1_SKIP, then the syscall should not be
683 * invoked. In this case, seccomp_phase1 will have set the return value
684 * using syscall_set_return_value.
686 * If it returns anything else, then the return value should be passed
687 * to seccomp_phase2 from a context in which ptrace hooks are safe.
689 u32 seccomp_phase1(struct seccomp_data *sd)
691 int mode = current->seccomp.mode;
692 int this_syscall = sd ? sd->nr :
693 syscall_get_nr(current, task_pt_regs(current));
696 case SECCOMP_MODE_STRICT:
697 __secure_computing_strict(this_syscall); /* may call do_exit */
698 return SECCOMP_PHASE1_OK;
699 #ifdef CONFIG_SECCOMP_FILTER
700 case SECCOMP_MODE_FILTER:
701 return __seccomp_phase1_filter(this_syscall, sd);
709 * seccomp_phase2() - finish slow path seccomp work for the current syscall
710 * @phase1_result: The return value from seccomp_phase1()
712 * This must be called from a context in which ptrace hooks can be used.
714 * Returns 0 if the syscall should be processed or -1 to skip the syscall.
716 int seccomp_phase2(u32 phase1_result)
718 struct pt_regs *regs = task_pt_regs(current);
719 u32 action = phase1_result & SECCOMP_RET_ACTION;
720 int data = phase1_result & SECCOMP_RET_DATA;
722 BUG_ON(action != SECCOMP_RET_TRACE);
724 audit_seccomp(syscall_get_nr(current, regs), 0, action);
726 /* Skip these calls if there is no tracer. */
727 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
728 syscall_set_return_value(current, regs,
733 /* Allow the BPF to provide the event message */
734 ptrace_event(PTRACE_EVENT_SECCOMP, data);
736 * The delivery of a fatal signal during event
737 * notification may silently skip tracer notification.
738 * Terminating the task now avoids executing a system
739 * call that may not be intended.
741 if (fatal_signal_pending(current))
743 if (syscall_get_nr(current, regs) < 0)
744 return -1; /* Explicit request to skip. */
748 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
750 long prctl_get_seccomp(void)
752 return current->seccomp.mode;
756 * seccomp_set_mode_strict: internal function for setting strict seccomp
758 * Once current->seccomp.mode is non-zero, it may not be changed.
760 * Returns 0 on success or -EINVAL on failure.
762 static long seccomp_set_mode_strict(void)
764 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
767 spin_lock_irq(¤t->sighand->siglock);
769 if (!seccomp_may_assign_mode(seccomp_mode))
775 seccomp_assign_mode(current, seccomp_mode);
779 spin_unlock_irq(¤t->sighand->siglock);
784 #ifdef CONFIG_SECCOMP_FILTER
786 * seccomp_set_mode_filter: internal function for setting seccomp filter
787 * @flags: flags to change filter behavior
788 * @filter: struct sock_fprog containing filter
790 * This function may be called repeatedly to install additional filters.
791 * Every filter successfully installed will be evaluated (in reverse order)
792 * for each system call the task makes.
794 * Once current->seccomp.mode is non-zero, it may not be changed.
796 * Returns 0 on success or -EINVAL on failure.
798 static long seccomp_set_mode_filter(unsigned int flags,
799 const char __user *filter)
801 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
802 struct seccomp_filter *prepared = NULL;
805 /* Validate flags. */
806 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
809 /* Prepare the new filter before holding any locks. */
810 prepared = seccomp_prepare_user_filter(filter);
811 if (IS_ERR(prepared))
812 return PTR_ERR(prepared);
815 * Make sure we cannot change seccomp or nnp state via TSYNC
816 * while another thread is in the middle of calling exec.
818 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
819 mutex_lock_killable(¤t->signal->cred_guard_mutex))
822 spin_lock_irq(¤t->sighand->siglock);
824 if (!seccomp_may_assign_mode(seccomp_mode))
827 ret = seccomp_attach_filter(flags, prepared);
830 /* Do not free the successfully attached filter. */
833 seccomp_assign_mode(current, seccomp_mode);
835 spin_unlock_irq(¤t->sighand->siglock);
836 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
837 mutex_unlock(¤t->signal->cred_guard_mutex);
839 seccomp_filter_free(prepared);
843 static inline long seccomp_set_mode_filter(unsigned int flags,
844 const char __user *filter)
850 /* Common entry point for both prctl and syscall. */
851 static long do_seccomp(unsigned int op, unsigned int flags,
852 const char __user *uargs)
855 case SECCOMP_SET_MODE_STRICT:
856 if (flags != 0 || uargs != NULL)
858 return seccomp_set_mode_strict();
859 case SECCOMP_SET_MODE_FILTER:
860 return seccomp_set_mode_filter(flags, uargs);
866 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
867 const char __user *, uargs)
869 return do_seccomp(op, flags, uargs);
873 * prctl_set_seccomp: configures current->seccomp.mode
874 * @seccomp_mode: requested mode to use
875 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
877 * Returns 0 on success or -EINVAL on failure.
879 long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
884 switch (seccomp_mode) {
885 case SECCOMP_MODE_STRICT:
886 op = SECCOMP_SET_MODE_STRICT;
888 * Setting strict mode through prctl always ignored filter,
889 * so make sure it is always NULL here to pass the internal
890 * check in do_seccomp().
894 case SECCOMP_MODE_FILTER:
895 op = SECCOMP_SET_MODE_FILTER;
902 /* prctl interface doesn't have flags, so they are always zero. */
903 return do_seccomp(op, 0, uargs);