1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/kernel/signal.c
5 * Copyright (C) 1991, 1992 Linus Torvalds
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
14 #include <linux/slab.h>
15 #include <linux/export.h>
16 #include <linux/init.h>
17 #include <linux/sched/mm.h>
18 #include <linux/sched/user.h>
19 #include <linux/sched/debug.h>
20 #include <linux/sched/task.h>
21 #include <linux/sched/task_stack.h>
22 #include <linux/sched/cputime.h>
23 #include <linux/file.h>
25 #include <linux/proc_fs.h>
26 #include <linux/tty.h>
27 #include <linux/binfmts.h>
28 #include <linux/coredump.h>
29 #include <linux/security.h>
30 #include <linux/syscalls.h>
31 #include <linux/ptrace.h>
32 #include <linux/signal.h>
33 #include <linux/signalfd.h>
34 #include <linux/ratelimit.h>
35 #include <linux/tracehook.h>
36 #include <linux/capability.h>
37 #include <linux/freezer.h>
38 #include <linux/pid_namespace.h>
39 #include <linux/nsproxy.h>
40 #include <linux/user_namespace.h>
41 #include <linux/uprobes.h>
42 #include <linux/compat.h>
43 #include <linux/cn_proc.h>
44 #include <linux/compiler.h>
45 #include <linux/posix-timers.h>
46 #include <linux/cgroup.h>
47 #include <linux/audit.h>
49 #define CREATE_TRACE_POINTS
50 #include <trace/events/signal.h>
52 #include <asm/param.h>
53 #include <linux/uaccess.h>
54 #include <asm/unistd.h>
55 #include <asm/siginfo.h>
56 #include <asm/cacheflush.h>
57 #include <asm/syscall.h> /* for syscall_get_* */
60 * SLAB caches for signal bits.
63 static struct kmem_cache *sigqueue_cachep;
65 int print_fatal_signals __read_mostly;
67 static void __user *sig_handler(struct task_struct *t, int sig)
69 return t->sighand->action[sig - 1].sa.sa_handler;
72 static inline bool sig_handler_ignored(void __user *handler, int sig)
74 /* Is it explicitly or implicitly ignored? */
75 return handler == SIG_IGN ||
76 (handler == SIG_DFL && sig_kernel_ignore(sig));
79 static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
83 handler = sig_handler(t, sig);
85 /* SIGKILL and SIGSTOP may not be sent to the global init */
86 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
89 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
90 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
93 /* Only allow kernel generated signals to this kthread */
94 if (unlikely((t->flags & PF_KTHREAD) &&
95 (handler == SIG_KTHREAD_KERNEL) && !force))
98 return sig_handler_ignored(handler, sig);
101 static bool sig_ignored(struct task_struct *t, int sig, bool force)
104 * Blocked signals are never ignored, since the
105 * signal handler may change by the time it is
108 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
112 * Tracers may want to know about even ignored signal unless it
113 * is SIGKILL which can't be reported anyway but can be ignored
114 * by SIGNAL_UNKILLABLE task.
116 if (t->ptrace && sig != SIGKILL)
119 return sig_task_ignored(t, sig, force);
123 * Re-calculate pending state from the set of locally pending
124 * signals, globally pending signals, and blocked signals.
126 static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
131 switch (_NSIG_WORDS) {
133 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
134 ready |= signal->sig[i] &~ blocked->sig[i];
137 case 4: ready = signal->sig[3] &~ blocked->sig[3];
138 ready |= signal->sig[2] &~ blocked->sig[2];
139 ready |= signal->sig[1] &~ blocked->sig[1];
140 ready |= signal->sig[0] &~ blocked->sig[0];
143 case 2: ready = signal->sig[1] &~ blocked->sig[1];
144 ready |= signal->sig[0] &~ blocked->sig[0];
147 case 1: ready = signal->sig[0] &~ blocked->sig[0];
152 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
154 static bool recalc_sigpending_tsk(struct task_struct *t)
156 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
157 PENDING(&t->pending, &t->blocked) ||
158 PENDING(&t->signal->shared_pending, &t->blocked) ||
159 cgroup_task_frozen(t)) {
160 set_tsk_thread_flag(t, TIF_SIGPENDING);
165 * We must never clear the flag in another thread, or in current
166 * when it's possible the current syscall is returning -ERESTART*.
167 * So we don't clear it here, and only callers who know they should do.
173 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
174 * This is superfluous when called on current, the wakeup is a harmless no-op.
176 void recalc_sigpending_and_wake(struct task_struct *t)
178 if (recalc_sigpending_tsk(t))
179 signal_wake_up(t, 0);
182 void recalc_sigpending(void)
184 if (!recalc_sigpending_tsk(current) && !freezing(current))
185 clear_thread_flag(TIF_SIGPENDING);
188 EXPORT_SYMBOL(recalc_sigpending);
190 void calculate_sigpending(void)
192 /* Have any signals or users of TIF_SIGPENDING been delayed
195 spin_lock_irq(¤t->sighand->siglock);
196 set_tsk_thread_flag(current, TIF_SIGPENDING);
198 spin_unlock_irq(¤t->sighand->siglock);
201 /* Given the mask, find the first available signal that should be serviced. */
203 #define SYNCHRONOUS_MASK \
204 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
205 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
207 int next_signal(struct sigpending *pending, sigset_t *mask)
209 unsigned long i, *s, *m, x;
212 s = pending->signal.sig;
216 * Handle the first word specially: it contains the
217 * synchronous signals that need to be dequeued first.
221 if (x & SYNCHRONOUS_MASK)
222 x &= SYNCHRONOUS_MASK;
227 switch (_NSIG_WORDS) {
229 for (i = 1; i < _NSIG_WORDS; ++i) {
233 sig = ffz(~x) + i*_NSIG_BPW + 1;
242 sig = ffz(~x) + _NSIG_BPW + 1;
253 static inline void print_dropped_signal(int sig)
255 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
257 if (!print_fatal_signals)
260 if (!__ratelimit(&ratelimit_state))
263 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
264 current->comm, current->pid, sig);
268 * task_set_jobctl_pending - set jobctl pending bits
270 * @mask: pending bits to set
272 * Clear @mask from @task->jobctl. @mask must be subset of
273 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
274 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
275 * cleared. If @task is already being killed or exiting, this function
279 * Must be called with @task->sighand->siglock held.
282 * %true if @mask is set, %false if made noop because @task was dying.
284 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
286 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
287 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
288 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
290 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
293 if (mask & JOBCTL_STOP_SIGMASK)
294 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
296 task->jobctl |= mask;
301 * task_clear_jobctl_trapping - clear jobctl trapping bit
304 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
305 * Clear it and wake up the ptracer. Note that we don't need any further
306 * locking. @task->siglock guarantees that @task->parent points to the
310 * Must be called with @task->sighand->siglock held.
312 void task_clear_jobctl_trapping(struct task_struct *task)
314 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
315 task->jobctl &= ~JOBCTL_TRAPPING;
316 smp_mb(); /* advised by wake_up_bit() */
317 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
322 * task_clear_jobctl_pending - clear jobctl pending bits
324 * @mask: pending bits to clear
326 * Clear @mask from @task->jobctl. @mask must be subset of
327 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
328 * STOP bits are cleared together.
330 * If clearing of @mask leaves no stop or trap pending, this function calls
331 * task_clear_jobctl_trapping().
334 * Must be called with @task->sighand->siglock held.
336 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
338 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
340 if (mask & JOBCTL_STOP_PENDING)
341 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
343 task->jobctl &= ~mask;
345 if (!(task->jobctl & JOBCTL_PENDING_MASK))
346 task_clear_jobctl_trapping(task);
350 * task_participate_group_stop - participate in a group stop
351 * @task: task participating in a group stop
353 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
354 * Group stop states are cleared and the group stop count is consumed if
355 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
356 * stop, the appropriate `SIGNAL_*` flags are set.
359 * Must be called with @task->sighand->siglock held.
362 * %true if group stop completion should be notified to the parent, %false
365 static bool task_participate_group_stop(struct task_struct *task)
367 struct signal_struct *sig = task->signal;
368 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
370 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
372 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
377 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
378 sig->group_stop_count--;
381 * Tell the caller to notify completion iff we are entering into a
382 * fresh group stop. Read comment in do_signal_stop() for details.
384 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
385 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
391 void task_join_group_stop(struct task_struct *task)
393 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
394 struct signal_struct *sig = current->signal;
396 if (sig->group_stop_count) {
397 sig->group_stop_count++;
398 mask |= JOBCTL_STOP_CONSUME;
399 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
402 /* Have the new thread join an on-going signal group stop */
403 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
407 * allocate a new signal queue record
408 * - this may be called without locks if and only if t == current, otherwise an
409 * appropriate lock must be held to stop the target task from exiting
411 static struct sigqueue *
412 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
413 int override_rlimit, const unsigned int sigqueue_flags)
415 struct sigqueue *q = NULL;
416 struct ucounts *ucounts = NULL;
420 * Protect access to @t credentials. This can go away when all
421 * callers hold rcu read lock.
423 * NOTE! A pending signal will hold on to the user refcount,
424 * and we get/put the refcount only when the sigpending count
425 * changes from/to zero.
428 ucounts = task_ucounts(t);
429 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
434 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
435 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
437 print_dropped_signal(sig);
440 if (unlikely(q == NULL)) {
441 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
443 INIT_LIST_HEAD(&q->list);
444 q->flags = sigqueue_flags;
445 q->ucounts = ucounts;
450 static void __sigqueue_free(struct sigqueue *q)
452 if (q->flags & SIGQUEUE_PREALLOC)
455 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
458 kmem_cache_free(sigqueue_cachep, q);
461 void flush_sigqueue(struct sigpending *queue)
465 sigemptyset(&queue->signal);
466 while (!list_empty(&queue->list)) {
467 q = list_entry(queue->list.next, struct sigqueue , list);
468 list_del_init(&q->list);
474 * Flush all pending signals for this kthread.
476 void flush_signals(struct task_struct *t)
480 spin_lock_irqsave(&t->sighand->siglock, flags);
481 clear_tsk_thread_flag(t, TIF_SIGPENDING);
482 flush_sigqueue(&t->pending);
483 flush_sigqueue(&t->signal->shared_pending);
484 spin_unlock_irqrestore(&t->sighand->siglock, flags);
486 EXPORT_SYMBOL(flush_signals);
488 #ifdef CONFIG_POSIX_TIMERS
489 static void __flush_itimer_signals(struct sigpending *pending)
491 sigset_t signal, retain;
492 struct sigqueue *q, *n;
494 signal = pending->signal;
495 sigemptyset(&retain);
497 list_for_each_entry_safe(q, n, &pending->list, list) {
498 int sig = q->info.si_signo;
500 if (likely(q->info.si_code != SI_TIMER)) {
501 sigaddset(&retain, sig);
503 sigdelset(&signal, sig);
504 list_del_init(&q->list);
509 sigorsets(&pending->signal, &signal, &retain);
512 void flush_itimer_signals(void)
514 struct task_struct *tsk = current;
517 spin_lock_irqsave(&tsk->sighand->siglock, flags);
518 __flush_itimer_signals(&tsk->pending);
519 __flush_itimer_signals(&tsk->signal->shared_pending);
520 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
524 void ignore_signals(struct task_struct *t)
528 for (i = 0; i < _NSIG; ++i)
529 t->sighand->action[i].sa.sa_handler = SIG_IGN;
535 * Flush all handlers for a task.
539 flush_signal_handlers(struct task_struct *t, int force_default)
542 struct k_sigaction *ka = &t->sighand->action[0];
543 for (i = _NSIG ; i != 0 ; i--) {
544 if (force_default || ka->sa.sa_handler != SIG_IGN)
545 ka->sa.sa_handler = SIG_DFL;
547 #ifdef __ARCH_HAS_SA_RESTORER
548 ka->sa.sa_restorer = NULL;
550 sigemptyset(&ka->sa.sa_mask);
555 bool unhandled_signal(struct task_struct *tsk, int sig)
557 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
558 if (is_global_init(tsk))
561 if (handler != SIG_IGN && handler != SIG_DFL)
564 /* if ptraced, let the tracer determine */
568 static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
571 struct sigqueue *q, *first = NULL;
574 * Collect the siginfo appropriate to this signal. Check if
575 * there is another siginfo for the same signal.
577 list_for_each_entry(q, &list->list, list) {
578 if (q->info.si_signo == sig) {
585 sigdelset(&list->signal, sig);
589 list_del_init(&first->list);
590 copy_siginfo(info, &first->info);
593 (first->flags & SIGQUEUE_PREALLOC) &&
594 (info->si_code == SI_TIMER) &&
595 (info->si_sys_private);
597 __sigqueue_free(first);
600 * Ok, it wasn't in the queue. This must be
601 * a fast-pathed signal or we must have been
602 * out of queue space. So zero out the info.
605 info->si_signo = sig;
607 info->si_code = SI_USER;
613 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
614 kernel_siginfo_t *info, bool *resched_timer)
616 int sig = next_signal(pending, mask);
619 collect_signal(sig, pending, info, resched_timer);
624 * Dequeue a signal and return the element to the caller, which is
625 * expected to free it.
627 * All callers have to hold the siglock.
629 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
631 bool resched_timer = false;
634 /* We only dequeue private signals from ourselves, we don't let
635 * signalfd steal them
637 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
639 signr = __dequeue_signal(&tsk->signal->shared_pending,
640 mask, info, &resched_timer);
641 #ifdef CONFIG_POSIX_TIMERS
645 * itimers are process shared and we restart periodic
646 * itimers in the signal delivery path to prevent DoS
647 * attacks in the high resolution timer case. This is
648 * compliant with the old way of self-restarting
649 * itimers, as the SIGALRM is a legacy signal and only
650 * queued once. Changing the restart behaviour to
651 * restart the timer in the signal dequeue path is
652 * reducing the timer noise on heavy loaded !highres
655 if (unlikely(signr == SIGALRM)) {
656 struct hrtimer *tmr = &tsk->signal->real_timer;
658 if (!hrtimer_is_queued(tmr) &&
659 tsk->signal->it_real_incr != 0) {
660 hrtimer_forward(tmr, tmr->base->get_time(),
661 tsk->signal->it_real_incr);
662 hrtimer_restart(tmr);
672 if (unlikely(sig_kernel_stop(signr))) {
674 * Set a marker that we have dequeued a stop signal. Our
675 * caller might release the siglock and then the pending
676 * stop signal it is about to process is no longer in the
677 * pending bitmasks, but must still be cleared by a SIGCONT
678 * (and overruled by a SIGKILL). So those cases clear this
679 * shared flag after we've set it. Note that this flag may
680 * remain set after the signal we return is ignored or
681 * handled. That doesn't matter because its only purpose
682 * is to alert stop-signal processing code when another
683 * processor has come along and cleared the flag.
685 current->jobctl |= JOBCTL_STOP_DEQUEUED;
687 #ifdef CONFIG_POSIX_TIMERS
690 * Release the siglock to ensure proper locking order
691 * of timer locks outside of siglocks. Note, we leave
692 * irqs disabled here, since the posix-timers code is
693 * about to disable them again anyway.
695 spin_unlock(&tsk->sighand->siglock);
696 posixtimer_rearm(info);
697 spin_lock(&tsk->sighand->siglock);
699 /* Don't expose the si_sys_private value to userspace */
700 info->si_sys_private = 0;
705 EXPORT_SYMBOL_GPL(dequeue_signal);
707 static int dequeue_synchronous_signal(kernel_siginfo_t *info)
709 struct task_struct *tsk = current;
710 struct sigpending *pending = &tsk->pending;
711 struct sigqueue *q, *sync = NULL;
714 * Might a synchronous signal be in the queue?
716 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
720 * Return the first synchronous signal in the queue.
722 list_for_each_entry(q, &pending->list, list) {
723 /* Synchronous signals have a positive si_code */
724 if ((q->info.si_code > SI_USER) &&
725 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
733 * Check if there is another siginfo for the same signal.
735 list_for_each_entry_continue(q, &pending->list, list) {
736 if (q->info.si_signo == sync->info.si_signo)
740 sigdelset(&pending->signal, sync->info.si_signo);
743 list_del_init(&sync->list);
744 copy_siginfo(info, &sync->info);
745 __sigqueue_free(sync);
746 return info->si_signo;
750 * Tell a process that it has a new active signal..
752 * NOTE! we rely on the previous spin_lock to
753 * lock interrupts for us! We can only be called with
754 * "siglock" held, and the local interrupt must
755 * have been disabled when that got acquired!
757 * No need to set need_resched since signal event passing
758 * goes through ->blocked
760 void signal_wake_up_state(struct task_struct *t, unsigned int state)
762 set_tsk_thread_flag(t, TIF_SIGPENDING);
764 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
765 * case. We don't check t->state here because there is a race with it
766 * executing another processor and just now entering stopped state.
767 * By using wake_up_state, we ensure the process will wake up and
768 * handle its death signal.
770 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
775 * Remove signals in mask from the pending set and queue.
776 * Returns 1 if any signals were found.
778 * All callers must be holding the siglock.
780 static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
782 struct sigqueue *q, *n;
785 sigandsets(&m, mask, &s->signal);
786 if (sigisemptyset(&m))
789 sigandnsets(&s->signal, &s->signal, mask);
790 list_for_each_entry_safe(q, n, &s->list, list) {
791 if (sigismember(mask, q->info.si_signo)) {
792 list_del_init(&q->list);
798 static inline int is_si_special(const struct kernel_siginfo *info)
800 return info <= SEND_SIG_PRIV;
803 static inline bool si_fromuser(const struct kernel_siginfo *info)
805 return info == SEND_SIG_NOINFO ||
806 (!is_si_special(info) && SI_FROMUSER(info));
810 * called with RCU read lock from check_kill_permission()
812 static bool kill_ok_by_cred(struct task_struct *t)
814 const struct cred *cred = current_cred();
815 const struct cred *tcred = __task_cred(t);
817 return uid_eq(cred->euid, tcred->suid) ||
818 uid_eq(cred->euid, tcred->uid) ||
819 uid_eq(cred->uid, tcred->suid) ||
820 uid_eq(cred->uid, tcred->uid) ||
821 ns_capable(tcred->user_ns, CAP_KILL);
825 * Bad permissions for sending the signal
826 * - the caller must hold the RCU read lock
828 static int check_kill_permission(int sig, struct kernel_siginfo *info,
829 struct task_struct *t)
834 if (!valid_signal(sig))
837 if (!si_fromuser(info))
840 error = audit_signal_info(sig, t); /* Let audit system see the signal */
844 if (!same_thread_group(current, t) &&
845 !kill_ok_by_cred(t)) {
848 sid = task_session(t);
850 * We don't return the error if sid == NULL. The
851 * task was unhashed, the caller must notice this.
853 if (!sid || sid == task_session(current))
861 return security_task_kill(t, info, sig, NULL);
865 * ptrace_trap_notify - schedule trap to notify ptracer
866 * @t: tracee wanting to notify tracer
868 * This function schedules sticky ptrace trap which is cleared on the next
869 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
872 * If @t is running, STOP trap will be taken. If trapped for STOP and
873 * ptracer is listening for events, tracee is woken up so that it can
874 * re-trap for the new event. If trapped otherwise, STOP trap will be
875 * eventually taken without returning to userland after the existing traps
876 * are finished by PTRACE_CONT.
879 * Must be called with @task->sighand->siglock held.
881 static void ptrace_trap_notify(struct task_struct *t)
883 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
884 assert_spin_locked(&t->sighand->siglock);
886 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
887 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
891 * Handle magic process-wide effects of stop/continue signals. Unlike
892 * the signal actions, these happen immediately at signal-generation
893 * time regardless of blocking, ignoring, or handling. This does the
894 * actual continuing for SIGCONT, but not the actual stopping for stop
895 * signals. The process stop is done as a signal action for SIG_DFL.
897 * Returns true if the signal should be actually delivered, otherwise
898 * it should be dropped.
900 static bool prepare_signal(int sig, struct task_struct *p, bool force)
902 struct signal_struct *signal = p->signal;
903 struct task_struct *t;
906 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
907 if (!(signal->flags & SIGNAL_GROUP_EXIT))
908 return sig == SIGKILL;
910 * The process is in the middle of dying, nothing to do.
912 } else if (sig_kernel_stop(sig)) {
914 * This is a stop signal. Remove SIGCONT from all queues.
916 siginitset(&flush, sigmask(SIGCONT));
917 flush_sigqueue_mask(&flush, &signal->shared_pending);
918 for_each_thread(p, t)
919 flush_sigqueue_mask(&flush, &t->pending);
920 } else if (sig == SIGCONT) {
923 * Remove all stop signals from all queues, wake all threads.
925 siginitset(&flush, SIG_KERNEL_STOP_MASK);
926 flush_sigqueue_mask(&flush, &signal->shared_pending);
927 for_each_thread(p, t) {
928 flush_sigqueue_mask(&flush, &t->pending);
929 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
930 if (likely(!(t->ptrace & PT_SEIZED)))
931 wake_up_state(t, __TASK_STOPPED);
933 ptrace_trap_notify(t);
937 * Notify the parent with CLD_CONTINUED if we were stopped.
939 * If we were in the middle of a group stop, we pretend it
940 * was already finished, and then continued. Since SIGCHLD
941 * doesn't queue we report only CLD_STOPPED, as if the next
942 * CLD_CONTINUED was dropped.
945 if (signal->flags & SIGNAL_STOP_STOPPED)
946 why |= SIGNAL_CLD_CONTINUED;
947 else if (signal->group_stop_count)
948 why |= SIGNAL_CLD_STOPPED;
952 * The first thread which returns from do_signal_stop()
953 * will take ->siglock, notice SIGNAL_CLD_MASK, and
954 * notify its parent. See get_signal().
956 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
957 signal->group_stop_count = 0;
958 signal->group_exit_code = 0;
962 return !sig_ignored(p, sig, force);
966 * Test if P wants to take SIG. After we've checked all threads with this,
967 * it's equivalent to finding no threads not blocking SIG. Any threads not
968 * blocking SIG were ruled out because they are not running and already
969 * have pending signals. Such threads will dequeue from the shared queue
970 * as soon as they're available, so putting the signal on the shared queue
971 * will be equivalent to sending it to one such thread.
973 static inline bool wants_signal(int sig, struct task_struct *p)
975 if (sigismember(&p->blocked, sig))
978 if (p->flags & PF_EXITING)
984 if (task_is_stopped_or_traced(p))
987 return task_curr(p) || !task_sigpending(p);
990 static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
992 struct signal_struct *signal = p->signal;
993 struct task_struct *t;
996 * Now find a thread we can wake up to take the signal off the queue.
998 * If the main thread wants the signal, it gets first crack.
999 * Probably the least surprising to the average bear.
1001 if (wants_signal(sig, p))
1003 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1005 * There is just one thread and it does not need to be woken.
1006 * It will dequeue unblocked signals before it runs again.
1011 * Otherwise try to find a suitable thread.
1013 t = signal->curr_target;
1014 while (!wants_signal(sig, t)) {
1016 if (t == signal->curr_target)
1018 * No thread needs to be woken.
1019 * Any eligible threads will see
1020 * the signal in the queue soon.
1024 signal->curr_target = t;
1028 * Found a killable thread. If the signal will be fatal,
1029 * then start taking the whole group down immediately.
1031 if (sig_fatal(p, sig) &&
1032 !(signal->flags & SIGNAL_GROUP_EXIT) &&
1033 !sigismember(&t->real_blocked, sig) &&
1034 (sig == SIGKILL || !p->ptrace)) {
1036 * This signal will be fatal to the whole group.
1038 if (!sig_kernel_coredump(sig)) {
1040 * Start a group exit and wake everybody up.
1041 * This way we don't have other threads
1042 * running and doing things after a slower
1043 * thread has the fatal signal pending.
1045 signal->flags = SIGNAL_GROUP_EXIT;
1046 signal->group_exit_code = sig;
1047 signal->group_stop_count = 0;
1050 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1051 sigaddset(&t->pending.signal, SIGKILL);
1052 signal_wake_up(t, 1);
1053 } while_each_thread(p, t);
1059 * The signal is already in the shared-pending queue.
1060 * Tell the chosen thread to wake up and dequeue it.
1062 signal_wake_up(t, sig == SIGKILL);
1066 static inline bool legacy_queue(struct sigpending *signals, int sig)
1068 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1071 static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1072 enum pid_type type, bool force)
1074 struct sigpending *pending;
1076 int override_rlimit;
1077 int ret = 0, result;
1079 assert_spin_locked(&t->sighand->siglock);
1081 result = TRACE_SIGNAL_IGNORED;
1082 if (!prepare_signal(sig, t, force))
1085 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1087 * Short-circuit ignored signals and support queuing
1088 * exactly one non-rt signal, so that we can get more
1089 * detailed information about the cause of the signal.
1091 result = TRACE_SIGNAL_ALREADY_PENDING;
1092 if (legacy_queue(pending, sig))
1095 result = TRACE_SIGNAL_DELIVERED;
1097 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1099 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1103 * Real-time signals must be queued if sent by sigqueue, or
1104 * some other real-time mechanism. It is implementation
1105 * defined whether kill() does so. We attempt to do so, on
1106 * the principle of least surprise, but since kill is not
1107 * allowed to fail with EAGAIN when low on memory we just
1108 * make sure at least one signal gets delivered and don't
1109 * pass on the info struct.
1112 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1114 override_rlimit = 0;
1116 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1119 list_add_tail(&q->list, &pending->list);
1120 switch ((unsigned long) info) {
1121 case (unsigned long) SEND_SIG_NOINFO:
1122 clear_siginfo(&q->info);
1123 q->info.si_signo = sig;
1124 q->info.si_errno = 0;
1125 q->info.si_code = SI_USER;
1126 q->info.si_pid = task_tgid_nr_ns(current,
1127 task_active_pid_ns(t));
1130 from_kuid_munged(task_cred_xxx(t, user_ns),
1134 case (unsigned long) SEND_SIG_PRIV:
1135 clear_siginfo(&q->info);
1136 q->info.si_signo = sig;
1137 q->info.si_errno = 0;
1138 q->info.si_code = SI_KERNEL;
1143 copy_siginfo(&q->info, info);
1146 } else if (!is_si_special(info) &&
1147 sig >= SIGRTMIN && info->si_code != SI_USER) {
1149 * Queue overflow, abort. We may abort if the
1150 * signal was rt and sent by user using something
1151 * other than kill().
1153 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1158 * This is a silent loss of information. We still
1159 * send the signal, but the *info bits are lost.
1161 result = TRACE_SIGNAL_LOSE_INFO;
1165 signalfd_notify(t, sig);
1166 sigaddset(&pending->signal, sig);
1168 /* Let multiprocess signals appear after on-going forks */
1169 if (type > PIDTYPE_TGID) {
1170 struct multiprocess_signals *delayed;
1171 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1172 sigset_t *signal = &delayed->signal;
1173 /* Can't queue both a stop and a continue signal */
1175 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1176 else if (sig_kernel_stop(sig))
1177 sigdelset(signal, SIGCONT);
1178 sigaddset(signal, sig);
1182 complete_signal(sig, t, type);
1184 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1188 static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1191 switch (siginfo_layout(info->si_signo, info->si_code)) {
1200 case SIL_FAULT_TRAPNO:
1201 case SIL_FAULT_MCEERR:
1202 case SIL_FAULT_BNDERR:
1203 case SIL_FAULT_PKUERR:
1204 case SIL_FAULT_PERF_EVENT:
1212 static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1215 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1218 if (info == SEND_SIG_NOINFO) {
1219 /* Force if sent from an ancestor pid namespace */
1220 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1221 } else if (info == SEND_SIG_PRIV) {
1222 /* Don't ignore kernel generated signals */
1224 } else if (has_si_pid_and_uid(info)) {
1225 /* SIGKILL and SIGSTOP is special or has ids */
1226 struct user_namespace *t_user_ns;
1229 t_user_ns = task_cred_xxx(t, user_ns);
1230 if (current_user_ns() != t_user_ns) {
1231 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1232 info->si_uid = from_kuid_munged(t_user_ns, uid);
1236 /* A kernel generated signal? */
1237 force = (info->si_code == SI_KERNEL);
1239 /* From an ancestor pid namespace? */
1240 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1245 return __send_signal(sig, info, t, type, force);
1248 static void print_fatal_signal(int signr)
1250 struct pt_regs *regs = signal_pt_regs();
1251 pr_info("potentially unexpected fatal signal %d.\n", signr);
1253 #if defined(__i386__) && !defined(__arch_um__)
1254 pr_info("code at %08lx: ", regs->ip);
1257 for (i = 0; i < 16; i++) {
1260 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1262 pr_cont("%02x ", insn);
1272 static int __init setup_print_fatal_signals(char *str)
1274 get_option (&str, &print_fatal_signals);
1279 __setup("print-fatal-signals=", setup_print_fatal_signals);
1282 __group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1284 return send_signal(sig, info, p, PIDTYPE_TGID);
1287 int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1290 unsigned long flags;
1293 if (lock_task_sighand(p, &flags)) {
1294 ret = send_signal(sig, info, p, type);
1295 unlock_task_sighand(p, &flags);
1302 * Force a signal that the process can't ignore: if necessary
1303 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1305 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1306 * since we do not want to have a signal handler that was blocked
1307 * be invoked when user space had explicitly blocked it.
1309 * We don't want to have recursive SIGSEGV's etc, for example,
1310 * that is why we also clear SIGNAL_UNKILLABLE.
1313 force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, bool sigdfl)
1315 unsigned long int flags;
1316 int ret, blocked, ignored;
1317 struct k_sigaction *action;
1318 int sig = info->si_signo;
1320 spin_lock_irqsave(&t->sighand->siglock, flags);
1321 action = &t->sighand->action[sig-1];
1322 ignored = action->sa.sa_handler == SIG_IGN;
1323 blocked = sigismember(&t->blocked, sig);
1324 if (blocked || ignored || sigdfl) {
1325 action->sa.sa_handler = SIG_DFL;
1326 action->sa.sa_flags |= SA_IMMUTABLE;
1328 sigdelset(&t->blocked, sig);
1329 recalc_sigpending_and_wake(t);
1333 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1334 * debugging to leave init killable.
1336 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1337 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1338 ret = send_signal(sig, info, t, PIDTYPE_PID);
1339 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1344 int force_sig_info(struct kernel_siginfo *info)
1346 return force_sig_info_to_task(info, current, false);
1350 * Nuke all other threads in the group.
1352 int zap_other_threads(struct task_struct *p)
1354 struct task_struct *t = p;
1357 p->signal->group_stop_count = 0;
1359 while_each_thread(p, t) {
1360 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1363 /* Don't bother with already dead threads */
1366 sigaddset(&t->pending.signal, SIGKILL);
1367 signal_wake_up(t, 1);
1373 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1374 unsigned long *flags)
1376 struct sighand_struct *sighand;
1380 sighand = rcu_dereference(tsk->sighand);
1381 if (unlikely(sighand == NULL))
1385 * This sighand can be already freed and even reused, but
1386 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1387 * initializes ->siglock: this slab can't go away, it has
1388 * the same object type, ->siglock can't be reinitialized.
1390 * We need to ensure that tsk->sighand is still the same
1391 * after we take the lock, we can race with de_thread() or
1392 * __exit_signal(). In the latter case the next iteration
1393 * must see ->sighand == NULL.
1395 spin_lock_irqsave(&sighand->siglock, *flags);
1396 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1398 spin_unlock_irqrestore(&sighand->siglock, *flags);
1405 #ifdef CONFIG_LOCKDEP
1406 void lockdep_assert_task_sighand_held(struct task_struct *task)
1408 struct sighand_struct *sighand;
1411 sighand = rcu_dereference(task->sighand);
1413 lockdep_assert_held(&sighand->siglock);
1421 * send signal info to all the members of a group
1423 int group_send_sig_info(int sig, struct kernel_siginfo *info,
1424 struct task_struct *p, enum pid_type type)
1429 ret = check_kill_permission(sig, info, p);
1433 ret = do_send_sig_info(sig, info, p, type);
1439 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1440 * control characters do (^C, ^Z etc)
1441 * - the caller must hold at least a readlock on tasklist_lock
1443 int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1445 struct task_struct *p = NULL;
1446 int retval, success;
1450 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1451 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1454 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1455 return success ? 0 : retval;
1458 int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1461 struct task_struct *p;
1465 p = pid_task(pid, PIDTYPE_PID);
1467 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1469 if (likely(!p || error != -ESRCH))
1473 * The task was unhashed in between, try again. If it
1474 * is dead, pid_task() will return NULL, if we race with
1475 * de_thread() it will find the new leader.
1480 static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1484 error = kill_pid_info(sig, info, find_vpid(pid));
1489 static inline bool kill_as_cred_perm(const struct cred *cred,
1490 struct task_struct *target)
1492 const struct cred *pcred = __task_cred(target);
1494 return uid_eq(cred->euid, pcred->suid) ||
1495 uid_eq(cred->euid, pcred->uid) ||
1496 uid_eq(cred->uid, pcred->suid) ||
1497 uid_eq(cred->uid, pcred->uid);
1501 * The usb asyncio usage of siginfo is wrong. The glibc support
1502 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1503 * AKA after the generic fields:
1504 * kernel_pid_t si_pid;
1505 * kernel_uid32_t si_uid;
1506 * sigval_t si_value;
1508 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1509 * after the generic fields is:
1510 * void __user *si_addr;
1512 * This is a practical problem when there is a 64bit big endian kernel
1513 * and a 32bit userspace. As the 32bit address will encoded in the low
1514 * 32bits of the pointer. Those low 32bits will be stored at higher
1515 * address than appear in a 32 bit pointer. So userspace will not
1516 * see the address it was expecting for it's completions.
1518 * There is nothing in the encoding that can allow
1519 * copy_siginfo_to_user32 to detect this confusion of formats, so
1520 * handle this by requiring the caller of kill_pid_usb_asyncio to
1521 * notice when this situration takes place and to store the 32bit
1522 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1525 int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1526 struct pid *pid, const struct cred *cred)
1528 struct kernel_siginfo info;
1529 struct task_struct *p;
1530 unsigned long flags;
1533 if (!valid_signal(sig))
1536 clear_siginfo(&info);
1537 info.si_signo = sig;
1538 info.si_errno = errno;
1539 info.si_code = SI_ASYNCIO;
1540 *((sigval_t *)&info.si_pid) = addr;
1543 p = pid_task(pid, PIDTYPE_PID);
1548 if (!kill_as_cred_perm(cred, p)) {
1552 ret = security_task_kill(p, &info, sig, cred);
1557 if (lock_task_sighand(p, &flags)) {
1558 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1559 unlock_task_sighand(p, &flags);
1567 EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1570 * kill_something_info() interprets pid in interesting ways just like kill(2).
1572 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1573 * is probably wrong. Should make it like BSD or SYSV.
1576 static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1581 return kill_proc_info(sig, info, pid);
1583 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1587 read_lock(&tasklist_lock);
1589 ret = __kill_pgrp_info(sig, info,
1590 pid ? find_vpid(-pid) : task_pgrp(current));
1592 int retval = 0, count = 0;
1593 struct task_struct * p;
1595 for_each_process(p) {
1596 if (task_pid_vnr(p) > 1 &&
1597 !same_thread_group(p, current)) {
1598 int err = group_send_sig_info(sig, info, p,
1605 ret = count ? retval : -ESRCH;
1607 read_unlock(&tasklist_lock);
1613 * These are for backward compatibility with the rest of the kernel source.
1616 int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1619 * Make sure legacy kernel users don't send in bad values
1620 * (normal paths check this in check_kill_permission).
1622 if (!valid_signal(sig))
1625 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1627 EXPORT_SYMBOL(send_sig_info);
1629 #define __si_special(priv) \
1630 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1633 send_sig(int sig, struct task_struct *p, int priv)
1635 return send_sig_info(sig, __si_special(priv), p);
1637 EXPORT_SYMBOL(send_sig);
1639 void force_sig(int sig)
1641 struct kernel_siginfo info;
1643 clear_siginfo(&info);
1644 info.si_signo = sig;
1646 info.si_code = SI_KERNEL;
1649 force_sig_info(&info);
1651 EXPORT_SYMBOL(force_sig);
1653 void force_fatal_sig(int sig)
1655 struct kernel_siginfo info;
1657 clear_siginfo(&info);
1658 info.si_signo = sig;
1660 info.si_code = SI_KERNEL;
1663 force_sig_info_to_task(&info, current, true);
1667 * When things go south during signal handling, we
1668 * will force a SIGSEGV. And if the signal that caused
1669 * the problem was already a SIGSEGV, we'll want to
1670 * make sure we don't even try to deliver the signal..
1672 void force_sigsegv(int sig)
1675 force_fatal_sig(SIGSEGV);
1680 int force_sig_fault_to_task(int sig, int code, void __user *addr
1681 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1682 , struct task_struct *t)
1684 struct kernel_siginfo info;
1686 clear_siginfo(&info);
1687 info.si_signo = sig;
1689 info.si_code = code;
1690 info.si_addr = addr;
1693 info.si_flags = flags;
1696 return force_sig_info_to_task(&info, t, false);
1699 int force_sig_fault(int sig, int code, void __user *addr
1700 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1702 return force_sig_fault_to_task(sig, code, addr
1703 ___ARCH_SI_IA64(imm, flags, isr), current);
1706 int send_sig_fault(int sig, int code, void __user *addr
1707 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1708 , struct task_struct *t)
1710 struct kernel_siginfo info;
1712 clear_siginfo(&info);
1713 info.si_signo = sig;
1715 info.si_code = code;
1716 info.si_addr = addr;
1719 info.si_flags = flags;
1722 return send_sig_info(info.si_signo, &info, t);
1725 int force_sig_mceerr(int code, void __user *addr, short lsb)
1727 struct kernel_siginfo info;
1729 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1730 clear_siginfo(&info);
1731 info.si_signo = SIGBUS;
1733 info.si_code = code;
1734 info.si_addr = addr;
1735 info.si_addr_lsb = lsb;
1736 return force_sig_info(&info);
1739 int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1741 struct kernel_siginfo info;
1743 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1744 clear_siginfo(&info);
1745 info.si_signo = SIGBUS;
1747 info.si_code = code;
1748 info.si_addr = addr;
1749 info.si_addr_lsb = lsb;
1750 return send_sig_info(info.si_signo, &info, t);
1752 EXPORT_SYMBOL(send_sig_mceerr);
1754 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1756 struct kernel_siginfo info;
1758 clear_siginfo(&info);
1759 info.si_signo = SIGSEGV;
1761 info.si_code = SEGV_BNDERR;
1762 info.si_addr = addr;
1763 info.si_lower = lower;
1764 info.si_upper = upper;
1765 return force_sig_info(&info);
1769 int force_sig_pkuerr(void __user *addr, u32 pkey)
1771 struct kernel_siginfo info;
1773 clear_siginfo(&info);
1774 info.si_signo = SIGSEGV;
1776 info.si_code = SEGV_PKUERR;
1777 info.si_addr = addr;
1778 info.si_pkey = pkey;
1779 return force_sig_info(&info);
1783 int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
1785 struct kernel_siginfo info;
1787 clear_siginfo(&info);
1788 info.si_signo = SIGTRAP;
1790 info.si_code = TRAP_PERF;
1791 info.si_addr = addr;
1792 info.si_perf_data = sig_data;
1793 info.si_perf_type = type;
1795 return force_sig_info(&info);
1799 * force_sig_seccomp - signals the task to allow in-process syscall emulation
1800 * @syscall: syscall number to send to userland
1801 * @reason: filter-supplied reason code to send to userland (via si_errno)
1803 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1805 int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1807 struct kernel_siginfo info;
1809 clear_siginfo(&info);
1810 info.si_signo = SIGSYS;
1811 info.si_code = SYS_SECCOMP;
1812 info.si_call_addr = (void __user *)KSTK_EIP(current);
1813 info.si_errno = reason;
1814 info.si_arch = syscall_get_arch(current);
1815 info.si_syscall = syscall;
1816 return force_sig_info_to_task(&info, current, force_coredump);
1819 /* For the crazy architectures that include trap information in
1820 * the errno field, instead of an actual errno value.
1822 int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1824 struct kernel_siginfo info;
1826 clear_siginfo(&info);
1827 info.si_signo = SIGTRAP;
1828 info.si_errno = errno;
1829 info.si_code = TRAP_HWBKPT;
1830 info.si_addr = addr;
1831 return force_sig_info(&info);
1834 /* For the rare architectures that include trap information using
1837 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1839 struct kernel_siginfo info;
1841 clear_siginfo(&info);
1842 info.si_signo = sig;
1844 info.si_code = code;
1845 info.si_addr = addr;
1846 info.si_trapno = trapno;
1847 return force_sig_info(&info);
1850 /* For the rare architectures that include trap information using
1853 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1854 struct task_struct *t)
1856 struct kernel_siginfo info;
1858 clear_siginfo(&info);
1859 info.si_signo = sig;
1861 info.si_code = code;
1862 info.si_addr = addr;
1863 info.si_trapno = trapno;
1864 return send_sig_info(info.si_signo, &info, t);
1867 int kill_pgrp(struct pid *pid, int sig, int priv)
1871 read_lock(&tasklist_lock);
1872 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1873 read_unlock(&tasklist_lock);
1877 EXPORT_SYMBOL(kill_pgrp);
1879 int kill_pid(struct pid *pid, int sig, int priv)
1881 return kill_pid_info(sig, __si_special(priv), pid);
1883 EXPORT_SYMBOL(kill_pid);
1886 * These functions support sending signals using preallocated sigqueue
1887 * structures. This is needed "because realtime applications cannot
1888 * afford to lose notifications of asynchronous events, like timer
1889 * expirations or I/O completions". In the case of POSIX Timers
1890 * we allocate the sigqueue structure from the timer_create. If this
1891 * allocation fails we are able to report the failure to the application
1892 * with an EAGAIN error.
1894 struct sigqueue *sigqueue_alloc(void)
1896 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1899 void sigqueue_free(struct sigqueue *q)
1901 unsigned long flags;
1902 spinlock_t *lock = ¤t->sighand->siglock;
1904 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1906 * We must hold ->siglock while testing q->list
1907 * to serialize with collect_signal() or with
1908 * __exit_signal()->flush_sigqueue().
1910 spin_lock_irqsave(lock, flags);
1911 q->flags &= ~SIGQUEUE_PREALLOC;
1913 * If it is queued it will be freed when dequeued,
1914 * like the "regular" sigqueue.
1916 if (!list_empty(&q->list))
1918 spin_unlock_irqrestore(lock, flags);
1924 int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1926 int sig = q->info.si_signo;
1927 struct sigpending *pending;
1928 struct task_struct *t;
1929 unsigned long flags;
1932 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1936 t = pid_task(pid, type);
1937 if (!t || !likely(lock_task_sighand(t, &flags)))
1940 ret = 1; /* the signal is ignored */
1941 result = TRACE_SIGNAL_IGNORED;
1942 if (!prepare_signal(sig, t, false))
1946 if (unlikely(!list_empty(&q->list))) {
1948 * If an SI_TIMER entry is already queue just increment
1949 * the overrun count.
1951 BUG_ON(q->info.si_code != SI_TIMER);
1952 q->info.si_overrun++;
1953 result = TRACE_SIGNAL_ALREADY_PENDING;
1956 q->info.si_overrun = 0;
1958 signalfd_notify(t, sig);
1959 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1960 list_add_tail(&q->list, &pending->list);
1961 sigaddset(&pending->signal, sig);
1962 complete_signal(sig, t, type);
1963 result = TRACE_SIGNAL_DELIVERED;
1965 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1966 unlock_task_sighand(t, &flags);
1972 static void do_notify_pidfd(struct task_struct *task)
1976 WARN_ON(task->exit_state == 0);
1977 pid = task_pid(task);
1978 wake_up_all(&pid->wait_pidfd);
1982 * Let a parent know about the death of a child.
1983 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1985 * Returns true if our parent ignored us and so we've switched to
1988 bool do_notify_parent(struct task_struct *tsk, int sig)
1990 struct kernel_siginfo info;
1991 unsigned long flags;
1992 struct sighand_struct *psig;
1993 bool autoreap = false;
1998 /* do_notify_parent_cldstop should have been called instead. */
1999 BUG_ON(task_is_stopped_or_traced(tsk));
2001 BUG_ON(!tsk->ptrace &&
2002 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2004 /* Wake up all pidfd waiters */
2005 do_notify_pidfd(tsk);
2007 if (sig != SIGCHLD) {
2009 * This is only possible if parent == real_parent.
2010 * Check if it has changed security domain.
2012 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2016 clear_siginfo(&info);
2017 info.si_signo = sig;
2020 * We are under tasklist_lock here so our parent is tied to
2021 * us and cannot change.
2023 * task_active_pid_ns will always return the same pid namespace
2024 * until a task passes through release_task.
2026 * write_lock() currently calls preempt_disable() which is the
2027 * same as rcu_read_lock(), but according to Oleg, this is not
2028 * correct to rely on this
2031 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2032 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2036 task_cputime(tsk, &utime, &stime);
2037 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2038 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2040 info.si_status = tsk->exit_code & 0x7f;
2041 if (tsk->exit_code & 0x80)
2042 info.si_code = CLD_DUMPED;
2043 else if (tsk->exit_code & 0x7f)
2044 info.si_code = CLD_KILLED;
2046 info.si_code = CLD_EXITED;
2047 info.si_status = tsk->exit_code >> 8;
2050 psig = tsk->parent->sighand;
2051 spin_lock_irqsave(&psig->siglock, flags);
2052 if (!tsk->ptrace && sig == SIGCHLD &&
2053 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2054 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2056 * We are exiting and our parent doesn't care. POSIX.1
2057 * defines special semantics for setting SIGCHLD to SIG_IGN
2058 * or setting the SA_NOCLDWAIT flag: we should be reaped
2059 * automatically and not left for our parent's wait4 call.
2060 * Rather than having the parent do it as a magic kind of
2061 * signal handler, we just set this to tell do_exit that we
2062 * can be cleaned up without becoming a zombie. Note that
2063 * we still call __wake_up_parent in this case, because a
2064 * blocked sys_wait4 might now return -ECHILD.
2066 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2067 * is implementation-defined: we do (if you don't want
2068 * it, just use SIG_IGN instead).
2071 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2075 * Send with __send_signal as si_pid and si_uid are in the
2076 * parent's namespaces.
2078 if (valid_signal(sig) && sig)
2079 __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2080 __wake_up_parent(tsk, tsk->parent);
2081 spin_unlock_irqrestore(&psig->siglock, flags);
2087 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2088 * @tsk: task reporting the state change
2089 * @for_ptracer: the notification is for ptracer
2090 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2092 * Notify @tsk's parent that the stopped/continued state has changed. If
2093 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2094 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2097 * Must be called with tasklist_lock at least read locked.
2099 static void do_notify_parent_cldstop(struct task_struct *tsk,
2100 bool for_ptracer, int why)
2102 struct kernel_siginfo info;
2103 unsigned long flags;
2104 struct task_struct *parent;
2105 struct sighand_struct *sighand;
2109 parent = tsk->parent;
2111 tsk = tsk->group_leader;
2112 parent = tsk->real_parent;
2115 clear_siginfo(&info);
2116 info.si_signo = SIGCHLD;
2119 * see comment in do_notify_parent() about the following 4 lines
2122 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2123 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2126 task_cputime(tsk, &utime, &stime);
2127 info.si_utime = nsec_to_clock_t(utime);
2128 info.si_stime = nsec_to_clock_t(stime);
2133 info.si_status = SIGCONT;
2136 info.si_status = tsk->signal->group_exit_code & 0x7f;
2139 info.si_status = tsk->exit_code & 0x7f;
2145 sighand = parent->sighand;
2146 spin_lock_irqsave(&sighand->siglock, flags);
2147 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2148 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2149 __group_send_sig_info(SIGCHLD, &info, parent);
2151 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2153 __wake_up_parent(tsk, parent);
2154 spin_unlock_irqrestore(&sighand->siglock, flags);
2158 * This must be called with current->sighand->siglock held.
2160 * This should be the path for all ptrace stops.
2161 * We always set current->last_siginfo while stopped here.
2162 * That makes it a way to test a stopped process for
2163 * being ptrace-stopped vs being job-control-stopped.
2165 * If we actually decide not to stop at all because the tracer
2166 * is gone, we keep current->exit_code unless clear_code.
2168 static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
2169 __releases(¤t->sighand->siglock)
2170 __acquires(¤t->sighand->siglock)
2172 bool gstop_done = false;
2174 if (arch_ptrace_stop_needed()) {
2176 * The arch code has something special to do before a
2177 * ptrace stop. This is allowed to block, e.g. for faults
2178 * on user stack pages. We can't keep the siglock while
2179 * calling arch_ptrace_stop, so we must release it now.
2180 * To preserve proper semantics, we must do this before
2181 * any signal bookkeeping like checking group_stop_count.
2183 spin_unlock_irq(¤t->sighand->siglock);
2185 spin_lock_irq(¤t->sighand->siglock);
2189 * schedule() will not sleep if there is a pending signal that
2190 * can awaken the task.
2192 set_special_state(TASK_TRACED);
2195 * We're committing to trapping. TRACED should be visible before
2196 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2197 * Also, transition to TRACED and updates to ->jobctl should be
2198 * atomic with respect to siglock and should be done after the arch
2199 * hook as siglock is released and regrabbed across it.
2204 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2206 * set_current_state() smp_wmb();
2208 * wait_task_stopped()
2209 * task_stopped_code()
2210 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2214 current->last_siginfo = info;
2215 current->exit_code = exit_code;
2218 * If @why is CLD_STOPPED, we're trapping to participate in a group
2219 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2220 * across siglock relocks since INTERRUPT was scheduled, PENDING
2221 * could be clear now. We act as if SIGCONT is received after
2222 * TASK_TRACED is entered - ignore it.
2224 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2225 gstop_done = task_participate_group_stop(current);
2227 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2228 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2229 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2230 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2232 /* entering a trap, clear TRAPPING */
2233 task_clear_jobctl_trapping(current);
2235 spin_unlock_irq(¤t->sighand->siglock);
2236 read_lock(&tasklist_lock);
2237 if (likely(current->ptrace)) {
2239 * Notify parents of the stop.
2241 * While ptraced, there are two parents - the ptracer and
2242 * the real_parent of the group_leader. The ptracer should
2243 * know about every stop while the real parent is only
2244 * interested in the completion of group stop. The states
2245 * for the two don't interact with each other. Notify
2246 * separately unless they're gonna be duplicates.
2248 do_notify_parent_cldstop(current, true, why);
2249 if (gstop_done && ptrace_reparented(current))
2250 do_notify_parent_cldstop(current, false, why);
2253 * Don't want to allow preemption here, because
2254 * sys_ptrace() needs this task to be inactive.
2256 * XXX: implement read_unlock_no_resched().
2259 read_unlock(&tasklist_lock);
2260 cgroup_enter_frozen();
2261 preempt_enable_no_resched();
2262 freezable_schedule();
2263 cgroup_leave_frozen(true);
2266 * By the time we got the lock, our tracer went away.
2267 * Don't drop the lock yet, another tracer may come.
2269 * If @gstop_done, the ptracer went away between group stop
2270 * completion and here. During detach, it would have set
2271 * JOBCTL_STOP_PENDING on us and we'll re-enter
2272 * TASK_STOPPED in do_signal_stop() on return, so notifying
2273 * the real parent of the group stop completion is enough.
2276 do_notify_parent_cldstop(current, false, why);
2278 /* tasklist protects us from ptrace_freeze_traced() */
2279 __set_current_state(TASK_RUNNING);
2281 current->exit_code = 0;
2282 read_unlock(&tasklist_lock);
2286 * We are back. Now reacquire the siglock before touching
2287 * last_siginfo, so that we are sure to have synchronized with
2288 * any signal-sending on another CPU that wants to examine it.
2290 spin_lock_irq(¤t->sighand->siglock);
2291 current->last_siginfo = NULL;
2293 /* LISTENING can be set only during STOP traps, clear it */
2294 current->jobctl &= ~JOBCTL_LISTENING;
2297 * Queued signals ignored us while we were stopped for tracing.
2298 * So check for any that we should take before resuming user mode.
2299 * This sets TIF_SIGPENDING, but never clears it.
2301 recalc_sigpending_tsk(current);
2304 static void ptrace_do_notify(int signr, int exit_code, int why)
2306 kernel_siginfo_t info;
2308 clear_siginfo(&info);
2309 info.si_signo = signr;
2310 info.si_code = exit_code;
2311 info.si_pid = task_pid_vnr(current);
2312 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2314 /* Let the debugger run. */
2315 ptrace_stop(exit_code, why, 1, &info);
2318 void ptrace_notify(int exit_code)
2320 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2321 if (unlikely(current->task_works))
2324 spin_lock_irq(¤t->sighand->siglock);
2325 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2326 spin_unlock_irq(¤t->sighand->siglock);
2330 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2331 * @signr: signr causing group stop if initiating
2333 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2334 * and participate in it. If already set, participate in the existing
2335 * group stop. If participated in a group stop (and thus slept), %true is
2336 * returned with siglock released.
2338 * If ptraced, this function doesn't handle stop itself. Instead,
2339 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2340 * untouched. The caller must ensure that INTERRUPT trap handling takes
2341 * places afterwards.
2344 * Must be called with @current->sighand->siglock held, which is released
2348 * %false if group stop is already cancelled or ptrace trap is scheduled.
2349 * %true if participated in group stop.
2351 static bool do_signal_stop(int signr)
2352 __releases(¤t->sighand->siglock)
2354 struct signal_struct *sig = current->signal;
2356 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2357 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2358 struct task_struct *t;
2360 /* signr will be recorded in task->jobctl for retries */
2361 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2363 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2364 unlikely(signal_group_exit(sig)))
2367 * There is no group stop already in progress. We must
2370 * While ptraced, a task may be resumed while group stop is
2371 * still in effect and then receive a stop signal and
2372 * initiate another group stop. This deviates from the
2373 * usual behavior as two consecutive stop signals can't
2374 * cause two group stops when !ptraced. That is why we
2375 * also check !task_is_stopped(t) below.
2377 * The condition can be distinguished by testing whether
2378 * SIGNAL_STOP_STOPPED is already set. Don't generate
2379 * group_exit_code in such case.
2381 * This is not necessary for SIGNAL_STOP_CONTINUED because
2382 * an intervening stop signal is required to cause two
2383 * continued events regardless of ptrace.
2385 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2386 sig->group_exit_code = signr;
2388 sig->group_stop_count = 0;
2390 if (task_set_jobctl_pending(current, signr | gstop))
2391 sig->group_stop_count++;
2394 while_each_thread(current, t) {
2396 * Setting state to TASK_STOPPED for a group
2397 * stop is always done with the siglock held,
2398 * so this check has no races.
2400 if (!task_is_stopped(t) &&
2401 task_set_jobctl_pending(t, signr | gstop)) {
2402 sig->group_stop_count++;
2403 if (likely(!(t->ptrace & PT_SEIZED)))
2404 signal_wake_up(t, 0);
2406 ptrace_trap_notify(t);
2411 if (likely(!current->ptrace)) {
2415 * If there are no other threads in the group, or if there
2416 * is a group stop in progress and we are the last to stop,
2417 * report to the parent.
2419 if (task_participate_group_stop(current))
2420 notify = CLD_STOPPED;
2422 set_special_state(TASK_STOPPED);
2423 spin_unlock_irq(¤t->sighand->siglock);
2426 * Notify the parent of the group stop completion. Because
2427 * we're not holding either the siglock or tasklist_lock
2428 * here, ptracer may attach inbetween; however, this is for
2429 * group stop and should always be delivered to the real
2430 * parent of the group leader. The new ptracer will get
2431 * its notification when this task transitions into
2435 read_lock(&tasklist_lock);
2436 do_notify_parent_cldstop(current, false, notify);
2437 read_unlock(&tasklist_lock);
2440 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2441 cgroup_enter_frozen();
2442 freezable_schedule();
2446 * While ptraced, group stop is handled by STOP trap.
2447 * Schedule it and let the caller deal with it.
2449 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2455 * do_jobctl_trap - take care of ptrace jobctl traps
2457 * When PT_SEIZED, it's used for both group stop and explicit
2458 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2459 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2460 * the stop signal; otherwise, %SIGTRAP.
2462 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2463 * number as exit_code and no siginfo.
2466 * Must be called with @current->sighand->siglock held, which may be
2467 * released and re-acquired before returning with intervening sleep.
2469 static void do_jobctl_trap(void)
2471 struct signal_struct *signal = current->signal;
2472 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2474 if (current->ptrace & PT_SEIZED) {
2475 if (!signal->group_stop_count &&
2476 !(signal->flags & SIGNAL_STOP_STOPPED))
2478 WARN_ON_ONCE(!signr);
2479 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2482 WARN_ON_ONCE(!signr);
2483 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2484 current->exit_code = 0;
2489 * do_freezer_trap - handle the freezer jobctl trap
2491 * Puts the task into frozen state, if only the task is not about to quit.
2492 * In this case it drops JOBCTL_TRAP_FREEZE.
2495 * Must be called with @current->sighand->siglock held,
2496 * which is always released before returning.
2498 static void do_freezer_trap(void)
2499 __releases(¤t->sighand->siglock)
2502 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2503 * let's make another loop to give it a chance to be handled.
2504 * In any case, we'll return back.
2506 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2507 JOBCTL_TRAP_FREEZE) {
2508 spin_unlock_irq(¤t->sighand->siglock);
2513 * Now we're sure that there is no pending fatal signal and no
2514 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2515 * immediately (if there is a non-fatal signal pending), and
2516 * put the task into sleep.
2518 __set_current_state(TASK_INTERRUPTIBLE);
2519 clear_thread_flag(TIF_SIGPENDING);
2520 spin_unlock_irq(¤t->sighand->siglock);
2521 cgroup_enter_frozen();
2522 freezable_schedule();
2525 static int ptrace_signal(int signr, kernel_siginfo_t *info)
2528 * We do not check sig_kernel_stop(signr) but set this marker
2529 * unconditionally because we do not know whether debugger will
2530 * change signr. This flag has no meaning unless we are going
2531 * to stop after return from ptrace_stop(). In this case it will
2532 * be checked in do_signal_stop(), we should only stop if it was
2533 * not cleared by SIGCONT while we were sleeping. See also the
2534 * comment in dequeue_signal().
2536 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2537 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2539 /* We're back. Did the debugger cancel the sig? */
2540 signr = current->exit_code;
2544 current->exit_code = 0;
2547 * Update the siginfo structure if the signal has
2548 * changed. If the debugger wanted something
2549 * specific in the siginfo structure then it should
2550 * have updated *info via PTRACE_SETSIGINFO.
2552 if (signr != info->si_signo) {
2553 clear_siginfo(info);
2554 info->si_signo = signr;
2556 info->si_code = SI_USER;
2558 info->si_pid = task_pid_vnr(current->parent);
2559 info->si_uid = from_kuid_munged(current_user_ns(),
2560 task_uid(current->parent));
2564 /* If the (new) signal is now blocked, requeue it. */
2565 if (sigismember(¤t->blocked, signr)) {
2566 send_signal(signr, info, current, PIDTYPE_PID);
2573 static void hide_si_addr_tag_bits(struct ksignal *ksig)
2575 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2577 case SIL_FAULT_TRAPNO:
2578 case SIL_FAULT_MCEERR:
2579 case SIL_FAULT_BNDERR:
2580 case SIL_FAULT_PKUERR:
2581 case SIL_FAULT_PERF_EVENT:
2582 ksig->info.si_addr = arch_untagged_si_addr(
2583 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2595 bool get_signal(struct ksignal *ksig)
2597 struct sighand_struct *sighand = current->sighand;
2598 struct signal_struct *signal = current->signal;
2601 if (unlikely(current->task_works))
2605 * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so
2606 * that the arch handlers don't all have to do it. If we get here
2607 * without TIF_SIGPENDING, just exit after running signal work.
2609 if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
2610 if (test_thread_flag(TIF_NOTIFY_SIGNAL))
2611 tracehook_notify_signal();
2612 if (!task_sigpending(current))
2616 if (unlikely(uprobe_deny_signal()))
2620 * Do this once, we can't return to user-mode if freezing() == T.
2621 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2622 * thus do not need another check after return.
2627 spin_lock_irq(&sighand->siglock);
2630 * Every stopped thread goes here after wakeup. Check to see if
2631 * we should notify the parent, prepare_signal(SIGCONT) encodes
2632 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2634 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2637 if (signal->flags & SIGNAL_CLD_CONTINUED)
2638 why = CLD_CONTINUED;
2642 signal->flags &= ~SIGNAL_CLD_MASK;
2644 spin_unlock_irq(&sighand->siglock);
2647 * Notify the parent that we're continuing. This event is
2648 * always per-process and doesn't make whole lot of sense
2649 * for ptracers, who shouldn't consume the state via
2650 * wait(2) either, but, for backward compatibility, notify
2651 * the ptracer of the group leader too unless it's gonna be
2654 read_lock(&tasklist_lock);
2655 do_notify_parent_cldstop(current, false, why);
2657 if (ptrace_reparented(current->group_leader))
2658 do_notify_parent_cldstop(current->group_leader,
2660 read_unlock(&tasklist_lock);
2665 /* Has this task already been marked for death? */
2666 if (signal_group_exit(signal)) {
2667 ksig->info.si_signo = signr = SIGKILL;
2668 sigdelset(¤t->pending.signal, SIGKILL);
2669 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2670 &sighand->action[SIGKILL - 1]);
2671 recalc_sigpending();
2676 struct k_sigaction *ka;
2678 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2682 if (unlikely(current->jobctl &
2683 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2684 if (current->jobctl & JOBCTL_TRAP_MASK) {
2686 spin_unlock_irq(&sighand->siglock);
2687 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2694 * If the task is leaving the frozen state, let's update
2695 * cgroup counters and reset the frozen bit.
2697 if (unlikely(cgroup_task_frozen(current))) {
2698 spin_unlock_irq(&sighand->siglock);
2699 cgroup_leave_frozen(false);
2704 * Signals generated by the execution of an instruction
2705 * need to be delivered before any other pending signals
2706 * so that the instruction pointer in the signal stack
2707 * frame points to the faulting instruction.
2709 signr = dequeue_synchronous_signal(&ksig->info);
2711 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2714 break; /* will return 0 */
2716 if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2717 !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2718 signr = ptrace_signal(signr, &ksig->info);
2723 ka = &sighand->action[signr-1];
2725 /* Trace actually delivered signals. */
2726 trace_signal_deliver(signr, &ksig->info, ka);
2728 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2730 if (ka->sa.sa_handler != SIG_DFL) {
2731 /* Run the handler. */
2734 if (ka->sa.sa_flags & SA_ONESHOT)
2735 ka->sa.sa_handler = SIG_DFL;
2737 break; /* will return non-zero "signr" value */
2741 * Now we are doing the default action for this signal.
2743 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2747 * Global init gets no signals it doesn't want.
2748 * Container-init gets no signals it doesn't want from same
2751 * Note that if global/container-init sees a sig_kernel_only()
2752 * signal here, the signal must have been generated internally
2753 * or must have come from an ancestor namespace. In either
2754 * case, the signal cannot be dropped.
2756 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2757 !sig_kernel_only(signr))
2760 if (sig_kernel_stop(signr)) {
2762 * The default action is to stop all threads in
2763 * the thread group. The job control signals
2764 * do nothing in an orphaned pgrp, but SIGSTOP
2765 * always works. Note that siglock needs to be
2766 * dropped during the call to is_orphaned_pgrp()
2767 * because of lock ordering with tasklist_lock.
2768 * This allows an intervening SIGCONT to be posted.
2769 * We need to check for that and bail out if necessary.
2771 if (signr != SIGSTOP) {
2772 spin_unlock_irq(&sighand->siglock);
2774 /* signals can be posted during this window */
2776 if (is_current_pgrp_orphaned())
2779 spin_lock_irq(&sighand->siglock);
2782 if (likely(do_signal_stop(ksig->info.si_signo))) {
2783 /* It released the siglock. */
2788 * We didn't actually stop, due to a race
2789 * with SIGCONT or something like that.
2795 spin_unlock_irq(&sighand->siglock);
2796 if (unlikely(cgroup_task_frozen(current)))
2797 cgroup_leave_frozen(true);
2800 * Anything else is fatal, maybe with a core dump.
2802 current->flags |= PF_SIGNALED;
2804 if (sig_kernel_coredump(signr)) {
2805 if (print_fatal_signals)
2806 print_fatal_signal(ksig->info.si_signo);
2807 proc_coredump_connector(current);
2809 * If it was able to dump core, this kills all
2810 * other threads in the group and synchronizes with
2811 * their demise. If we lost the race with another
2812 * thread getting here, it set group_exit_code
2813 * first and our do_group_exit call below will use
2814 * that value and ignore the one we pass it.
2816 do_coredump(&ksig->info);
2820 * PF_IO_WORKER threads will catch and exit on fatal signals
2821 * themselves. They have cleanup that must be performed, so
2822 * we cannot call do_exit() on their behalf.
2824 if (current->flags & PF_IO_WORKER)
2828 * Death signals, no core dump.
2830 do_group_exit(ksig->info.si_signo);
2833 spin_unlock_irq(&sighand->siglock);
2837 if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2838 hide_si_addr_tag_bits(ksig);
2840 return ksig->sig > 0;
2844 * signal_delivered -
2845 * @ksig: kernel signal struct
2846 * @stepping: nonzero if debugger single-step or block-step in use
2848 * This function should be called when a signal has successfully been
2849 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2850 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2851 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2853 static void signal_delivered(struct ksignal *ksig, int stepping)
2857 /* A signal was successfully delivered, and the
2858 saved sigmask was stored on the signal frame,
2859 and will be restored by sigreturn. So we can
2860 simply clear the restore sigmask flag. */
2861 clear_restore_sigmask();
2863 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2864 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2865 sigaddset(&blocked, ksig->sig);
2866 set_current_blocked(&blocked);
2867 if (current->sas_ss_flags & SS_AUTODISARM)
2868 sas_ss_reset(current);
2869 tracehook_signal_handler(stepping);
2872 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2875 force_sigsegv(ksig->sig);
2877 signal_delivered(ksig, stepping);
2881 * It could be that complete_signal() picked us to notify about the
2882 * group-wide signal. Other threads should be notified now to take
2883 * the shared signals in @which since we will not.
2885 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2888 struct task_struct *t;
2890 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2891 if (sigisemptyset(&retarget))
2895 while_each_thread(tsk, t) {
2896 if (t->flags & PF_EXITING)
2899 if (!has_pending_signals(&retarget, &t->blocked))
2901 /* Remove the signals this thread can handle. */
2902 sigandsets(&retarget, &retarget, &t->blocked);
2904 if (!task_sigpending(t))
2905 signal_wake_up(t, 0);
2907 if (sigisemptyset(&retarget))
2912 void exit_signals(struct task_struct *tsk)
2918 * @tsk is about to have PF_EXITING set - lock out users which
2919 * expect stable threadgroup.
2921 cgroup_threadgroup_change_begin(tsk);
2923 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2924 tsk->flags |= PF_EXITING;
2925 cgroup_threadgroup_change_end(tsk);
2929 spin_lock_irq(&tsk->sighand->siglock);
2931 * From now this task is not visible for group-wide signals,
2932 * see wants_signal(), do_signal_stop().
2934 tsk->flags |= PF_EXITING;
2936 cgroup_threadgroup_change_end(tsk);
2938 if (!task_sigpending(tsk))
2941 unblocked = tsk->blocked;
2942 signotset(&unblocked);
2943 retarget_shared_pending(tsk, &unblocked);
2945 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2946 task_participate_group_stop(tsk))
2947 group_stop = CLD_STOPPED;
2949 spin_unlock_irq(&tsk->sighand->siglock);
2952 * If group stop has completed, deliver the notification. This
2953 * should always go to the real parent of the group leader.
2955 if (unlikely(group_stop)) {
2956 read_lock(&tasklist_lock);
2957 do_notify_parent_cldstop(tsk, false, group_stop);
2958 read_unlock(&tasklist_lock);
2963 * System call entry points.
2967 * sys_restart_syscall - restart a system call
2969 SYSCALL_DEFINE0(restart_syscall)
2971 struct restart_block *restart = ¤t->restart_block;
2972 return restart->fn(restart);
2975 long do_no_restart_syscall(struct restart_block *param)
2980 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2982 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
2983 sigset_t newblocked;
2984 /* A set of now blocked but previously unblocked signals. */
2985 sigandnsets(&newblocked, newset, ¤t->blocked);
2986 retarget_shared_pending(tsk, &newblocked);
2988 tsk->blocked = *newset;
2989 recalc_sigpending();
2993 * set_current_blocked - change current->blocked mask
2996 * It is wrong to change ->blocked directly, this helper should be used
2997 * to ensure the process can't miss a shared signal we are going to block.
2999 void set_current_blocked(sigset_t *newset)
3001 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3002 __set_current_blocked(newset);
3005 void __set_current_blocked(const sigset_t *newset)
3007 struct task_struct *tsk = current;
3010 * In case the signal mask hasn't changed, there is nothing we need
3011 * to do. The current->blocked shouldn't be modified by other task.
3013 if (sigequalsets(&tsk->blocked, newset))
3016 spin_lock_irq(&tsk->sighand->siglock);
3017 __set_task_blocked(tsk, newset);
3018 spin_unlock_irq(&tsk->sighand->siglock);
3022 * This is also useful for kernel threads that want to temporarily
3023 * (or permanently) block certain signals.
3025 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3026 * interface happily blocks "unblockable" signals like SIGKILL
3029 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3031 struct task_struct *tsk = current;
3034 /* Lockless, only current can change ->blocked, never from irq */
3036 *oldset = tsk->blocked;
3040 sigorsets(&newset, &tsk->blocked, set);
3043 sigandnsets(&newset, &tsk->blocked, set);
3052 __set_current_blocked(&newset);
3055 EXPORT_SYMBOL(sigprocmask);
3058 * The api helps set app-provided sigmasks.
3060 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3061 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3063 * Note that it does set_restore_sigmask() in advance, so it must be always
3064 * paired with restore_saved_sigmask_unless() before return from syscall.
3066 int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3072 if (sigsetsize != sizeof(sigset_t))
3074 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3077 set_restore_sigmask();
3078 current->saved_sigmask = current->blocked;
3079 set_current_blocked(&kmask);
3084 #ifdef CONFIG_COMPAT
3085 int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3092 if (sigsetsize != sizeof(compat_sigset_t))
3094 if (get_compat_sigset(&kmask, umask))
3097 set_restore_sigmask();
3098 current->saved_sigmask = current->blocked;
3099 set_current_blocked(&kmask);
3106 * sys_rt_sigprocmask - change the list of currently blocked signals
3107 * @how: whether to add, remove, or set signals
3108 * @nset: stores pending signals
3109 * @oset: previous value of signal mask if non-null
3110 * @sigsetsize: size of sigset_t type
3112 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3113 sigset_t __user *, oset, size_t, sigsetsize)
3115 sigset_t old_set, new_set;
3118 /* XXX: Don't preclude handling different sized sigset_t's. */
3119 if (sigsetsize != sizeof(sigset_t))
3122 old_set = current->blocked;
3125 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3127 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3129 error = sigprocmask(how, &new_set, NULL);
3135 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3142 #ifdef CONFIG_COMPAT
3143 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3144 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3146 sigset_t old_set = current->blocked;
3148 /* XXX: Don't preclude handling different sized sigset_t's. */
3149 if (sigsetsize != sizeof(sigset_t))
3155 if (get_compat_sigset(&new_set, nset))
3157 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3159 error = sigprocmask(how, &new_set, NULL);
3163 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3167 static void do_sigpending(sigset_t *set)
3169 spin_lock_irq(¤t->sighand->siglock);
3170 sigorsets(set, ¤t->pending.signal,
3171 ¤t->signal->shared_pending.signal);
3172 spin_unlock_irq(¤t->sighand->siglock);
3174 /* Outside the lock because only this thread touches it. */
3175 sigandsets(set, ¤t->blocked, set);
3179 * sys_rt_sigpending - examine a pending signal that has been raised
3181 * @uset: stores pending signals
3182 * @sigsetsize: size of sigset_t type or larger
3184 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3188 if (sigsetsize > sizeof(*uset))
3191 do_sigpending(&set);
3193 if (copy_to_user(uset, &set, sigsetsize))
3199 #ifdef CONFIG_COMPAT
3200 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3201 compat_size_t, sigsetsize)
3205 if (sigsetsize > sizeof(*uset))
3208 do_sigpending(&set);
3210 return put_compat_sigset(uset, &set, sigsetsize);
3214 static const struct {
3215 unsigned char limit, layout;
3217 [SIGILL] = { NSIGILL, SIL_FAULT },
3218 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3219 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3220 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3221 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3223 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3225 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3226 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3227 [SIGSYS] = { NSIGSYS, SIL_SYS },
3230 static bool known_siginfo_layout(unsigned sig, int si_code)
3232 if (si_code == SI_KERNEL)
3234 else if ((si_code > SI_USER)) {
3235 if (sig_specific_sicodes(sig)) {
3236 if (si_code <= sig_sicodes[sig].limit)
3239 else if (si_code <= NSIGPOLL)
3242 else if (si_code >= SI_DETHREAD)
3244 else if (si_code == SI_ASYNCNL)
3249 enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3251 enum siginfo_layout layout = SIL_KILL;
3252 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3253 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3254 (si_code <= sig_sicodes[sig].limit)) {
3255 layout = sig_sicodes[sig].layout;
3256 /* Handle the exceptions */
3257 if ((sig == SIGBUS) &&
3258 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3259 layout = SIL_FAULT_MCEERR;
3260 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3261 layout = SIL_FAULT_BNDERR;
3263 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3264 layout = SIL_FAULT_PKUERR;
3266 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3267 layout = SIL_FAULT_PERF_EVENT;
3268 else if (IS_ENABLED(CONFIG_SPARC) &&
3269 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3270 layout = SIL_FAULT_TRAPNO;
3271 else if (IS_ENABLED(CONFIG_ALPHA) &&
3273 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3274 layout = SIL_FAULT_TRAPNO;
3276 else if (si_code <= NSIGPOLL)
3279 if (si_code == SI_TIMER)
3281 else if (si_code == SI_SIGIO)
3283 else if (si_code < 0)
3289 static inline char __user *si_expansion(const siginfo_t __user *info)
3291 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3294 int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3296 char __user *expansion = si_expansion(to);
3297 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3299 if (clear_user(expansion, SI_EXPANSION_SIZE))
3304 static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3305 const siginfo_t __user *from)
3307 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3308 char __user *expansion = si_expansion(from);
3309 char buf[SI_EXPANSION_SIZE];
3312 * An unknown si_code might need more than
3313 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3314 * extra bytes are 0. This guarantees copy_siginfo_to_user
3315 * will return this data to userspace exactly.
3317 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3319 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3327 static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3328 const siginfo_t __user *from)
3330 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3332 to->si_signo = signo;
3333 return post_copy_siginfo_from_user(to, from);
3336 int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3338 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3340 return post_copy_siginfo_from_user(to, from);
3343 #ifdef CONFIG_COMPAT
3345 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3346 * @to: compat siginfo destination
3347 * @from: kernel siginfo source
3349 * Note: This function does not work properly for the SIGCHLD on x32, but
3350 * fortunately it doesn't have to. The only valid callers for this function are
3351 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3352 * The latter does not care because SIGCHLD will never cause a coredump.
3354 void copy_siginfo_to_external32(struct compat_siginfo *to,
3355 const struct kernel_siginfo *from)
3357 memset(to, 0, sizeof(*to));
3359 to->si_signo = from->si_signo;
3360 to->si_errno = from->si_errno;
3361 to->si_code = from->si_code;
3362 switch(siginfo_layout(from->si_signo, from->si_code)) {
3364 to->si_pid = from->si_pid;
3365 to->si_uid = from->si_uid;
3368 to->si_tid = from->si_tid;
3369 to->si_overrun = from->si_overrun;
3370 to->si_int = from->si_int;
3373 to->si_band = from->si_band;
3374 to->si_fd = from->si_fd;
3377 to->si_addr = ptr_to_compat(from->si_addr);
3379 case SIL_FAULT_TRAPNO:
3380 to->si_addr = ptr_to_compat(from->si_addr);
3381 to->si_trapno = from->si_trapno;
3383 case SIL_FAULT_MCEERR:
3384 to->si_addr = ptr_to_compat(from->si_addr);
3385 to->si_addr_lsb = from->si_addr_lsb;
3387 case SIL_FAULT_BNDERR:
3388 to->si_addr = ptr_to_compat(from->si_addr);
3389 to->si_lower = ptr_to_compat(from->si_lower);
3390 to->si_upper = ptr_to_compat(from->si_upper);
3392 case SIL_FAULT_PKUERR:
3393 to->si_addr = ptr_to_compat(from->si_addr);
3394 to->si_pkey = from->si_pkey;
3396 case SIL_FAULT_PERF_EVENT:
3397 to->si_addr = ptr_to_compat(from->si_addr);
3398 to->si_perf_data = from->si_perf_data;
3399 to->si_perf_type = from->si_perf_type;
3402 to->si_pid = from->si_pid;
3403 to->si_uid = from->si_uid;
3404 to->si_status = from->si_status;
3405 to->si_utime = from->si_utime;
3406 to->si_stime = from->si_stime;
3409 to->si_pid = from->si_pid;
3410 to->si_uid = from->si_uid;
3411 to->si_int = from->si_int;
3414 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3415 to->si_syscall = from->si_syscall;
3416 to->si_arch = from->si_arch;
3421 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3422 const struct kernel_siginfo *from)
3424 struct compat_siginfo new;
3426 copy_siginfo_to_external32(&new, from);
3427 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3432 static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3433 const struct compat_siginfo *from)
3436 to->si_signo = from->si_signo;
3437 to->si_errno = from->si_errno;
3438 to->si_code = from->si_code;
3439 switch(siginfo_layout(from->si_signo, from->si_code)) {
3441 to->si_pid = from->si_pid;
3442 to->si_uid = from->si_uid;
3445 to->si_tid = from->si_tid;
3446 to->si_overrun = from->si_overrun;
3447 to->si_int = from->si_int;
3450 to->si_band = from->si_band;
3451 to->si_fd = from->si_fd;
3454 to->si_addr = compat_ptr(from->si_addr);
3456 case SIL_FAULT_TRAPNO:
3457 to->si_addr = compat_ptr(from->si_addr);
3458 to->si_trapno = from->si_trapno;
3460 case SIL_FAULT_MCEERR:
3461 to->si_addr = compat_ptr(from->si_addr);
3462 to->si_addr_lsb = from->si_addr_lsb;
3464 case SIL_FAULT_BNDERR:
3465 to->si_addr = compat_ptr(from->si_addr);
3466 to->si_lower = compat_ptr(from->si_lower);
3467 to->si_upper = compat_ptr(from->si_upper);
3469 case SIL_FAULT_PKUERR:
3470 to->si_addr = compat_ptr(from->si_addr);
3471 to->si_pkey = from->si_pkey;
3473 case SIL_FAULT_PERF_EVENT:
3474 to->si_addr = compat_ptr(from->si_addr);
3475 to->si_perf_data = from->si_perf_data;
3476 to->si_perf_type = from->si_perf_type;
3479 to->si_pid = from->si_pid;
3480 to->si_uid = from->si_uid;
3481 to->si_status = from->si_status;
3482 #ifdef CONFIG_X86_X32_ABI
3483 if (in_x32_syscall()) {
3484 to->si_utime = from->_sifields._sigchld_x32._utime;
3485 to->si_stime = from->_sifields._sigchld_x32._stime;
3489 to->si_utime = from->si_utime;
3490 to->si_stime = from->si_stime;
3494 to->si_pid = from->si_pid;
3495 to->si_uid = from->si_uid;
3496 to->si_int = from->si_int;
3499 to->si_call_addr = compat_ptr(from->si_call_addr);
3500 to->si_syscall = from->si_syscall;
3501 to->si_arch = from->si_arch;
3507 static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3508 const struct compat_siginfo __user *ufrom)
3510 struct compat_siginfo from;
3512 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3515 from.si_signo = signo;
3516 return post_copy_siginfo_from_user32(to, &from);
3519 int copy_siginfo_from_user32(struct kernel_siginfo *to,
3520 const struct compat_siginfo __user *ufrom)
3522 struct compat_siginfo from;
3524 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3527 return post_copy_siginfo_from_user32(to, &from);
3529 #endif /* CONFIG_COMPAT */
3532 * do_sigtimedwait - wait for queued signals specified in @which
3533 * @which: queued signals to wait for
3534 * @info: if non-null, the signal's siginfo is returned here
3535 * @ts: upper bound on process time suspension
3537 static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3538 const struct timespec64 *ts)
3540 ktime_t *to = NULL, timeout = KTIME_MAX;
3541 struct task_struct *tsk = current;
3542 sigset_t mask = *which;
3546 if (!timespec64_valid(ts))
3548 timeout = timespec64_to_ktime(*ts);
3553 * Invert the set of allowed signals to get those we want to block.
3555 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3558 spin_lock_irq(&tsk->sighand->siglock);
3559 sig = dequeue_signal(tsk, &mask, info);
3560 if (!sig && timeout) {
3562 * None ready, temporarily unblock those we're interested
3563 * while we are sleeping in so that we'll be awakened when
3564 * they arrive. Unblocking is always fine, we can avoid
3565 * set_current_blocked().
3567 tsk->real_blocked = tsk->blocked;
3568 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3569 recalc_sigpending();
3570 spin_unlock_irq(&tsk->sighand->siglock);
3572 __set_current_state(TASK_INTERRUPTIBLE);
3573 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3575 spin_lock_irq(&tsk->sighand->siglock);
3576 __set_task_blocked(tsk, &tsk->real_blocked);
3577 sigemptyset(&tsk->real_blocked);
3578 sig = dequeue_signal(tsk, &mask, info);
3580 spin_unlock_irq(&tsk->sighand->siglock);
3584 return ret ? -EINTR : -EAGAIN;
3588 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3590 * @uthese: queued signals to wait for
3591 * @uinfo: if non-null, the signal's siginfo is returned here
3592 * @uts: upper bound on process time suspension
3593 * @sigsetsize: size of sigset_t type
3595 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3596 siginfo_t __user *, uinfo,
3597 const struct __kernel_timespec __user *, uts,
3601 struct timespec64 ts;
3602 kernel_siginfo_t info;
3605 /* XXX: Don't preclude handling different sized sigset_t's. */
3606 if (sigsetsize != sizeof(sigset_t))
3609 if (copy_from_user(&these, uthese, sizeof(these)))
3613 if (get_timespec64(&ts, uts))
3617 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3619 if (ret > 0 && uinfo) {
3620 if (copy_siginfo_to_user(uinfo, &info))
3627 #ifdef CONFIG_COMPAT_32BIT_TIME
3628 SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3629 siginfo_t __user *, uinfo,
3630 const struct old_timespec32 __user *, uts,
3634 struct timespec64 ts;
3635 kernel_siginfo_t info;
3638 if (sigsetsize != sizeof(sigset_t))
3641 if (copy_from_user(&these, uthese, sizeof(these)))
3645 if (get_old_timespec32(&ts, uts))
3649 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3651 if (ret > 0 && uinfo) {
3652 if (copy_siginfo_to_user(uinfo, &info))
3660 #ifdef CONFIG_COMPAT
3661 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3662 struct compat_siginfo __user *, uinfo,
3663 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3666 struct timespec64 t;
3667 kernel_siginfo_t info;
3670 if (sigsetsize != sizeof(sigset_t))
3673 if (get_compat_sigset(&s, uthese))
3677 if (get_timespec64(&t, uts))
3681 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3683 if (ret > 0 && uinfo) {
3684 if (copy_siginfo_to_user32(uinfo, &info))
3691 #ifdef CONFIG_COMPAT_32BIT_TIME
3692 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3693 struct compat_siginfo __user *, uinfo,
3694 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3697 struct timespec64 t;
3698 kernel_siginfo_t info;
3701 if (sigsetsize != sizeof(sigset_t))
3704 if (get_compat_sigset(&s, uthese))
3708 if (get_old_timespec32(&t, uts))
3712 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3714 if (ret > 0 && uinfo) {
3715 if (copy_siginfo_to_user32(uinfo, &info))
3724 static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3726 clear_siginfo(info);
3727 info->si_signo = sig;
3729 info->si_code = SI_USER;
3730 info->si_pid = task_tgid_vnr(current);
3731 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3735 * sys_kill - send a signal to a process
3736 * @pid: the PID of the process
3737 * @sig: signal to be sent
3739 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3741 struct kernel_siginfo info;
3743 prepare_kill_siginfo(sig, &info);
3745 return kill_something_info(sig, &info, pid);
3749 * Verify that the signaler and signalee either are in the same pid namespace
3750 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3753 static bool access_pidfd_pidns(struct pid *pid)
3755 struct pid_namespace *active = task_active_pid_ns(current);
3756 struct pid_namespace *p = ns_of_pid(pid);
3769 static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3770 siginfo_t __user *info)
3772 #ifdef CONFIG_COMPAT
3774 * Avoid hooking up compat syscalls and instead handle necessary
3775 * conversions here. Note, this is a stop-gap measure and should not be
3776 * considered a generic solution.
3778 if (in_compat_syscall())
3779 return copy_siginfo_from_user32(
3780 kinfo, (struct compat_siginfo __user *)info);
3782 return copy_siginfo_from_user(kinfo, info);
3785 static struct pid *pidfd_to_pid(const struct file *file)
3789 pid = pidfd_pid(file);
3793 return tgid_pidfd_to_pid(file);
3797 * sys_pidfd_send_signal - Signal a process through a pidfd
3798 * @pidfd: file descriptor of the process
3799 * @sig: signal to send
3800 * @info: signal info
3801 * @flags: future flags
3803 * The syscall currently only signals via PIDTYPE_PID which covers
3804 * kill(<positive-pid>, <signal>. It does not signal threads or process
3806 * In order to extend the syscall to threads and process groups the @flags
3807 * argument should be used. In essence, the @flags argument will determine
3808 * what is signaled and not the file descriptor itself. Put in other words,
3809 * grouping is a property of the flags argument not a property of the file
3812 * Return: 0 on success, negative errno on failure
3814 SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3815 siginfo_t __user *, info, unsigned int, flags)
3820 kernel_siginfo_t kinfo;
3822 /* Enforce flags be set to 0 until we add an extension. */
3830 /* Is this a pidfd? */
3831 pid = pidfd_to_pid(f.file);
3838 if (!access_pidfd_pidns(pid))
3842 ret = copy_siginfo_from_user_any(&kinfo, info);
3847 if (unlikely(sig != kinfo.si_signo))
3850 /* Only allow sending arbitrary signals to yourself. */
3852 if ((task_pid(current) != pid) &&
3853 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3856 prepare_kill_siginfo(sig, &kinfo);
3859 ret = kill_pid_info(sig, &kinfo, pid);
3867 do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3869 struct task_struct *p;
3873 p = find_task_by_vpid(pid);
3874 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3875 error = check_kill_permission(sig, info, p);
3877 * The null signal is a permissions and process existence
3878 * probe. No signal is actually delivered.
3880 if (!error && sig) {
3881 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3883 * If lock_task_sighand() failed we pretend the task
3884 * dies after receiving the signal. The window is tiny,
3885 * and the signal is private anyway.
3887 if (unlikely(error == -ESRCH))
3896 static int do_tkill(pid_t tgid, pid_t pid, int sig)
3898 struct kernel_siginfo info;
3900 clear_siginfo(&info);
3901 info.si_signo = sig;
3903 info.si_code = SI_TKILL;
3904 info.si_pid = task_tgid_vnr(current);
3905 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3907 return do_send_specific(tgid, pid, sig, &info);
3911 * sys_tgkill - send signal to one specific thread
3912 * @tgid: the thread group ID of the thread
3913 * @pid: the PID of the thread
3914 * @sig: signal to be sent
3916 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3917 * exists but it's not belonging to the target process anymore. This
3918 * method solves the problem of threads exiting and PIDs getting reused.
3920 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3922 /* This is only valid for single tasks */
3923 if (pid <= 0 || tgid <= 0)
3926 return do_tkill(tgid, pid, sig);
3930 * sys_tkill - send signal to one specific task
3931 * @pid: the PID of the task
3932 * @sig: signal to be sent
3934 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3936 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3938 /* This is only valid for single tasks */
3942 return do_tkill(0, pid, sig);
3945 static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3947 /* Not even root can pretend to send signals from the kernel.
3948 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3950 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3951 (task_pid_vnr(current) != pid))
3954 /* POSIX.1b doesn't mention process groups. */
3955 return kill_proc_info(sig, info, pid);
3959 * sys_rt_sigqueueinfo - send signal information to a signal
3960 * @pid: the PID of the thread
3961 * @sig: signal to be sent
3962 * @uinfo: signal info to be sent
3964 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3965 siginfo_t __user *, uinfo)
3967 kernel_siginfo_t info;
3968 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3971 return do_rt_sigqueueinfo(pid, sig, &info);
3974 #ifdef CONFIG_COMPAT
3975 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3978 struct compat_siginfo __user *, uinfo)
3980 kernel_siginfo_t info;
3981 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3984 return do_rt_sigqueueinfo(pid, sig, &info);
3988 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
3990 /* This is only valid for single tasks */
3991 if (pid <= 0 || tgid <= 0)
3994 /* Not even root can pretend to send signals from the kernel.
3995 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3997 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3998 (task_pid_vnr(current) != pid))
4001 return do_send_specific(tgid, pid, sig, info);
4004 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4005 siginfo_t __user *, uinfo)
4007 kernel_siginfo_t info;
4008 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4011 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4014 #ifdef CONFIG_COMPAT
4015 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4019 struct compat_siginfo __user *, uinfo)
4021 kernel_siginfo_t info;
4022 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4025 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4030 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4032 void kernel_sigaction(int sig, __sighandler_t action)
4034 spin_lock_irq(¤t->sighand->siglock);
4035 current->sighand->action[sig - 1].sa.sa_handler = action;
4036 if (action == SIG_IGN) {
4040 sigaddset(&mask, sig);
4042 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4043 flush_sigqueue_mask(&mask, ¤t->pending);
4044 recalc_sigpending();
4046 spin_unlock_irq(¤t->sighand->siglock);
4048 EXPORT_SYMBOL(kernel_sigaction);
4050 void __weak sigaction_compat_abi(struct k_sigaction *act,
4051 struct k_sigaction *oact)
4055 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4057 struct task_struct *p = current, *t;
4058 struct k_sigaction *k;
4061 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4064 k = &p->sighand->action[sig-1];
4066 spin_lock_irq(&p->sighand->siglock);
4067 if (k->sa.sa_flags & SA_IMMUTABLE) {
4068 spin_unlock_irq(&p->sighand->siglock);
4075 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4076 * e.g. by having an architecture use the bit in their uapi.
4078 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4081 * Clear unknown flag bits in order to allow userspace to detect missing
4082 * support for flag bits and to allow the kernel to use non-uapi bits
4086 act->sa.sa_flags &= UAPI_SA_FLAGS;
4088 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4090 sigaction_compat_abi(act, oact);
4093 sigdelsetmask(&act->sa.sa_mask,
4094 sigmask(SIGKILL) | sigmask(SIGSTOP));
4098 * "Setting a signal action to SIG_IGN for a signal that is
4099 * pending shall cause the pending signal to be discarded,
4100 * whether or not it is blocked."
4102 * "Setting a signal action to SIG_DFL for a signal that is
4103 * pending and whose default action is to ignore the signal
4104 * (for example, SIGCHLD), shall cause the pending signal to
4105 * be discarded, whether or not it is blocked"
4107 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4109 sigaddset(&mask, sig);
4110 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4111 for_each_thread(p, t)
4112 flush_sigqueue_mask(&mask, &t->pending);
4116 spin_unlock_irq(&p->sighand->siglock);
4120 #ifdef CONFIG_DYNAMIC_SIGFRAME
4121 static inline void sigaltstack_lock(void)
4122 __acquires(¤t->sighand->siglock)
4124 spin_lock_irq(¤t->sighand->siglock);
4127 static inline void sigaltstack_unlock(void)
4128 __releases(¤t->sighand->siglock)
4130 spin_unlock_irq(¤t->sighand->siglock);
4133 static inline void sigaltstack_lock(void) { }
4134 static inline void sigaltstack_unlock(void) { }
4138 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4141 struct task_struct *t = current;
4145 memset(oss, 0, sizeof(stack_t));
4146 oss->ss_sp = (void __user *) t->sas_ss_sp;
4147 oss->ss_size = t->sas_ss_size;
4148 oss->ss_flags = sas_ss_flags(sp) |
4149 (current->sas_ss_flags & SS_FLAG_BITS);
4153 void __user *ss_sp = ss->ss_sp;
4154 size_t ss_size = ss->ss_size;
4155 unsigned ss_flags = ss->ss_flags;
4158 if (unlikely(on_sig_stack(sp)))
4161 ss_mode = ss_flags & ~SS_FLAG_BITS;
4162 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4167 if (ss_mode == SS_DISABLE) {
4171 if (unlikely(ss_size < min_ss_size))
4173 if (!sigaltstack_size_valid(ss_size))
4177 t->sas_ss_sp = (unsigned long) ss_sp;
4178 t->sas_ss_size = ss_size;
4179 t->sas_ss_flags = ss_flags;
4181 sigaltstack_unlock();
4186 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4190 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4192 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4193 current_user_stack_pointer(),
4195 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4200 int restore_altstack(const stack_t __user *uss)
4203 if (copy_from_user(&new, uss, sizeof(stack_t)))
4205 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4207 /* squash all but EFAULT for now */
4211 int __save_altstack(stack_t __user *uss, unsigned long sp)
4213 struct task_struct *t = current;
4214 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4215 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4216 __put_user(t->sas_ss_size, &uss->ss_size);
4220 #ifdef CONFIG_COMPAT
4221 static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4222 compat_stack_t __user *uoss_ptr)
4228 compat_stack_t uss32;
4229 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4231 uss.ss_sp = compat_ptr(uss32.ss_sp);
4232 uss.ss_flags = uss32.ss_flags;
4233 uss.ss_size = uss32.ss_size;
4235 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4236 compat_user_stack_pointer(),
4237 COMPAT_MINSIGSTKSZ);
4238 if (ret >= 0 && uoss_ptr) {
4240 memset(&old, 0, sizeof(old));
4241 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4242 old.ss_flags = uoss.ss_flags;
4243 old.ss_size = uoss.ss_size;
4244 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4250 COMPAT_SYSCALL_DEFINE2(sigaltstack,
4251 const compat_stack_t __user *, uss_ptr,
4252 compat_stack_t __user *, uoss_ptr)
4254 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4257 int compat_restore_altstack(const compat_stack_t __user *uss)
4259 int err = do_compat_sigaltstack(uss, NULL);
4260 /* squash all but -EFAULT for now */
4261 return err == -EFAULT ? err : 0;
4264 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4267 struct task_struct *t = current;
4268 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4270 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4271 __put_user(t->sas_ss_size, &uss->ss_size);
4276 #ifdef __ARCH_WANT_SYS_SIGPENDING
4279 * sys_sigpending - examine pending signals
4280 * @uset: where mask of pending signal is returned
4282 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4286 if (sizeof(old_sigset_t) > sizeof(*uset))
4289 do_sigpending(&set);
4291 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4297 #ifdef CONFIG_COMPAT
4298 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4302 do_sigpending(&set);
4304 return put_user(set.sig[0], set32);
4310 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
4312 * sys_sigprocmask - examine and change blocked signals
4313 * @how: whether to add, remove, or set signals
4314 * @nset: signals to add or remove (if non-null)
4315 * @oset: previous value of signal mask if non-null
4317 * Some platforms have their own version with special arguments;
4318 * others support only sys_rt_sigprocmask.
4321 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4322 old_sigset_t __user *, oset)
4324 old_sigset_t old_set, new_set;
4325 sigset_t new_blocked;
4327 old_set = current->blocked.sig[0];
4330 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4333 new_blocked = current->blocked;
4337 sigaddsetmask(&new_blocked, new_set);
4340 sigdelsetmask(&new_blocked, new_set);
4343 new_blocked.sig[0] = new_set;
4349 set_current_blocked(&new_blocked);
4353 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4359 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4361 #ifndef CONFIG_ODD_RT_SIGACTION
4363 * sys_rt_sigaction - alter an action taken by a process
4364 * @sig: signal to be sent
4365 * @act: new sigaction
4366 * @oact: used to save the previous sigaction
4367 * @sigsetsize: size of sigset_t type
4369 SYSCALL_DEFINE4(rt_sigaction, int, sig,
4370 const struct sigaction __user *, act,
4371 struct sigaction __user *, oact,
4374 struct k_sigaction new_sa, old_sa;
4377 /* XXX: Don't preclude handling different sized sigset_t's. */
4378 if (sigsetsize != sizeof(sigset_t))
4381 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4384 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4388 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4393 #ifdef CONFIG_COMPAT
4394 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4395 const struct compat_sigaction __user *, act,
4396 struct compat_sigaction __user *, oact,
4397 compat_size_t, sigsetsize)
4399 struct k_sigaction new_ka, old_ka;
4400 #ifdef __ARCH_HAS_SA_RESTORER
4401 compat_uptr_t restorer;
4405 /* XXX: Don't preclude handling different sized sigset_t's. */
4406 if (sigsetsize != sizeof(compat_sigset_t))
4410 compat_uptr_t handler;
4411 ret = get_user(handler, &act->sa_handler);
4412 new_ka.sa.sa_handler = compat_ptr(handler);
4413 #ifdef __ARCH_HAS_SA_RESTORER
4414 ret |= get_user(restorer, &act->sa_restorer);
4415 new_ka.sa.sa_restorer = compat_ptr(restorer);
4417 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4418 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4423 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4425 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4427 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4428 sizeof(oact->sa_mask));
4429 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4430 #ifdef __ARCH_HAS_SA_RESTORER
4431 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4432 &oact->sa_restorer);
4438 #endif /* !CONFIG_ODD_RT_SIGACTION */
4440 #ifdef CONFIG_OLD_SIGACTION
4441 SYSCALL_DEFINE3(sigaction, int, sig,
4442 const struct old_sigaction __user *, act,
4443 struct old_sigaction __user *, oact)
4445 struct k_sigaction new_ka, old_ka;
4450 if (!access_ok(act, sizeof(*act)) ||
4451 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4452 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4453 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4454 __get_user(mask, &act->sa_mask))
4456 #ifdef __ARCH_HAS_KA_RESTORER
4457 new_ka.ka_restorer = NULL;
4459 siginitset(&new_ka.sa.sa_mask, mask);
4462 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4465 if (!access_ok(oact, sizeof(*oact)) ||
4466 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4467 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4468 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4469 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4476 #ifdef CONFIG_COMPAT_OLD_SIGACTION
4477 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4478 const struct compat_old_sigaction __user *, act,
4479 struct compat_old_sigaction __user *, oact)
4481 struct k_sigaction new_ka, old_ka;
4483 compat_old_sigset_t mask;
4484 compat_uptr_t handler, restorer;
4487 if (!access_ok(act, sizeof(*act)) ||
4488 __get_user(handler, &act->sa_handler) ||
4489 __get_user(restorer, &act->sa_restorer) ||
4490 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4491 __get_user(mask, &act->sa_mask))
4494 #ifdef __ARCH_HAS_KA_RESTORER
4495 new_ka.ka_restorer = NULL;
4497 new_ka.sa.sa_handler = compat_ptr(handler);
4498 new_ka.sa.sa_restorer = compat_ptr(restorer);
4499 siginitset(&new_ka.sa.sa_mask, mask);
4502 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4505 if (!access_ok(oact, sizeof(*oact)) ||
4506 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4507 &oact->sa_handler) ||
4508 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4509 &oact->sa_restorer) ||
4510 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4511 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4518 #ifdef CONFIG_SGETMASK_SYSCALL
4521 * For backwards compatibility. Functionality superseded by sigprocmask.
4523 SYSCALL_DEFINE0(sgetmask)
4526 return current->blocked.sig[0];
4529 SYSCALL_DEFINE1(ssetmask, int, newmask)
4531 int old = current->blocked.sig[0];
4534 siginitset(&newset, newmask);
4535 set_current_blocked(&newset);
4539 #endif /* CONFIG_SGETMASK_SYSCALL */
4541 #ifdef __ARCH_WANT_SYS_SIGNAL
4543 * For backwards compatibility. Functionality superseded by sigaction.
4545 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4547 struct k_sigaction new_sa, old_sa;
4550 new_sa.sa.sa_handler = handler;
4551 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4552 sigemptyset(&new_sa.sa.sa_mask);
4554 ret = do_sigaction(sig, &new_sa, &old_sa);
4556 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4558 #endif /* __ARCH_WANT_SYS_SIGNAL */
4560 #ifdef __ARCH_WANT_SYS_PAUSE
4562 SYSCALL_DEFINE0(pause)
4564 while (!signal_pending(current)) {
4565 __set_current_state(TASK_INTERRUPTIBLE);
4568 return -ERESTARTNOHAND;
4573 static int sigsuspend(sigset_t *set)
4575 current->saved_sigmask = current->blocked;
4576 set_current_blocked(set);
4578 while (!signal_pending(current)) {
4579 __set_current_state(TASK_INTERRUPTIBLE);
4582 set_restore_sigmask();
4583 return -ERESTARTNOHAND;
4587 * sys_rt_sigsuspend - replace the signal mask for a value with the
4588 * @unewset value until a signal is received
4589 * @unewset: new signal mask value
4590 * @sigsetsize: size of sigset_t type
4592 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4596 /* XXX: Don't preclude handling different sized sigset_t's. */
4597 if (sigsetsize != sizeof(sigset_t))
4600 if (copy_from_user(&newset, unewset, sizeof(newset)))
4602 return sigsuspend(&newset);
4605 #ifdef CONFIG_COMPAT
4606 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4610 /* XXX: Don't preclude handling different sized sigset_t's. */
4611 if (sigsetsize != sizeof(sigset_t))
4614 if (get_compat_sigset(&newset, unewset))
4616 return sigsuspend(&newset);
4620 #ifdef CONFIG_OLD_SIGSUSPEND
4621 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4624 siginitset(&blocked, mask);
4625 return sigsuspend(&blocked);
4628 #ifdef CONFIG_OLD_SIGSUSPEND3
4629 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4632 siginitset(&blocked, mask);
4633 return sigsuspend(&blocked);
4637 __weak const char *arch_vma_name(struct vm_area_struct *vma)
4642 static inline void siginfo_buildtime_checks(void)
4644 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4646 /* Verify the offsets in the two siginfos match */
4647 #define CHECK_OFFSET(field) \
4648 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4651 CHECK_OFFSET(si_pid);
4652 CHECK_OFFSET(si_uid);
4655 CHECK_OFFSET(si_tid);
4656 CHECK_OFFSET(si_overrun);
4657 CHECK_OFFSET(si_value);
4660 CHECK_OFFSET(si_pid);
4661 CHECK_OFFSET(si_uid);
4662 CHECK_OFFSET(si_value);
4665 CHECK_OFFSET(si_pid);
4666 CHECK_OFFSET(si_uid);
4667 CHECK_OFFSET(si_status);
4668 CHECK_OFFSET(si_utime);
4669 CHECK_OFFSET(si_stime);
4672 CHECK_OFFSET(si_addr);
4673 CHECK_OFFSET(si_trapno);
4674 CHECK_OFFSET(si_addr_lsb);
4675 CHECK_OFFSET(si_lower);
4676 CHECK_OFFSET(si_upper);
4677 CHECK_OFFSET(si_pkey);
4678 CHECK_OFFSET(si_perf_data);
4679 CHECK_OFFSET(si_perf_type);
4682 CHECK_OFFSET(si_band);
4683 CHECK_OFFSET(si_fd);
4686 CHECK_OFFSET(si_call_addr);
4687 CHECK_OFFSET(si_syscall);
4688 CHECK_OFFSET(si_arch);
4692 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4693 offsetof(struct siginfo, si_addr));
4694 if (sizeof(int) == sizeof(void __user *)) {
4695 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4696 sizeof(void __user *));
4698 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4699 sizeof_field(struct siginfo, si_uid)) !=
4700 sizeof(void __user *));
4701 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4702 offsetof(struct siginfo, si_uid));
4704 #ifdef CONFIG_COMPAT
4705 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4706 offsetof(struct compat_siginfo, si_addr));
4707 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4708 sizeof(compat_uptr_t));
4709 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4710 sizeof_field(struct siginfo, si_pid));
4714 void __init signals_init(void)
4716 siginfo_buildtime_checks();
4718 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4721 #ifdef CONFIG_KGDB_KDB
4722 #include <linux/kdb.h>
4724 * kdb_send_sig - Allows kdb to send signals without exposing
4725 * signal internals. This function checks if the required locks are
4726 * available before calling the main signal code, to avoid kdb
4729 void kdb_send_sig(struct task_struct *t, int sig)
4731 static struct task_struct *kdb_prev_t;
4733 if (!spin_trylock(&t->sighand->siglock)) {
4734 kdb_printf("Can't do kill command now.\n"
4735 "The sigmask lock is held somewhere else in "
4736 "kernel, try again later\n");
4739 new_t = kdb_prev_t != t;
4741 if (!task_is_running(t) && new_t) {
4742 spin_unlock(&t->sighand->siglock);
4743 kdb_printf("Process is not RUNNING, sending a signal from "
4744 "kdb risks deadlock\n"
4745 "on the run queue locks. "
4746 "The signal has _not_ been sent.\n"
4747 "Reissue the kill command if you want to risk "
4751 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4752 spin_unlock(&t->sighand->siglock);
4754 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4757 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4759 #endif /* CONFIG_KGDB_KDB */