2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/export.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/coredump.h>
21 #include <linux/security.h>
22 #include <linux/syscalls.h>
23 #include <linux/ptrace.h>
24 #include <linux/signal.h>
25 #include <linux/signalfd.h>
26 #include <linux/ratelimit.h>
27 #include <linux/tracehook.h>
28 #include <linux/capability.h>
29 #include <linux/freezer.h>
30 #include <linux/pid_namespace.h>
31 #include <linux/nsproxy.h>
32 #include <linux/user_namespace.h>
33 #include <linux/uprobes.h>
34 #define CREATE_TRACE_POINTS
35 #include <trace/events/signal.h>
37 #include <asm/param.h>
38 #include <asm/uaccess.h>
39 #include <asm/unistd.h>
40 #include <asm/siginfo.h>
41 #include <asm/cacheflush.h>
42 #include "audit.h" /* audit_signal_info() */
45 * SLAB caches for signal bits.
48 static struct kmem_cache *sigqueue_cachep;
50 int print_fatal_signals __read_mostly;
52 static void __user *sig_handler(struct task_struct *t, int sig)
54 return t->sighand->action[sig - 1].sa.sa_handler;
57 static int sig_handler_ignored(void __user *handler, int sig)
59 /* Is it explicitly or implicitly ignored? */
60 return handler == SIG_IGN ||
61 (handler == SIG_DFL && sig_kernel_ignore(sig));
64 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
68 handler = sig_handler(t, sig);
70 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
71 handler == SIG_DFL && !force)
74 return sig_handler_ignored(handler, sig);
77 static int sig_ignored(struct task_struct *t, int sig, bool force)
80 * Blocked signals are never ignored, since the
81 * signal handler may change by the time it is
84 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
87 if (!sig_task_ignored(t, sig, force))
91 * Tracers may want to know about even ignored signals.
97 * Re-calculate pending state from the set of locally pending
98 * signals, globally pending signals, and blocked signals.
100 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105 switch (_NSIG_WORDS) {
107 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
108 ready |= signal->sig[i] &~ blocked->sig[i];
111 case 4: ready = signal->sig[3] &~ blocked->sig[3];
112 ready |= signal->sig[2] &~ blocked->sig[2];
113 ready |= signal->sig[1] &~ blocked->sig[1];
114 ready |= signal->sig[0] &~ blocked->sig[0];
117 case 2: ready = signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
121 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
128 static int recalc_sigpending_tsk(struct task_struct *t)
130 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
131 PENDING(&t->pending, &t->blocked) ||
132 PENDING(&t->signal->shared_pending, &t->blocked)) {
133 set_tsk_thread_flag(t, TIF_SIGPENDING);
137 * We must never clear the flag in another thread, or in current
138 * when it's possible the current syscall is returning -ERESTART*.
139 * So we don't clear it here, and only callers who know they should do.
145 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
146 * This is superfluous when called on current, the wakeup is a harmless no-op.
148 void recalc_sigpending_and_wake(struct task_struct *t)
150 if (recalc_sigpending_tsk(t))
151 signal_wake_up(t, 0);
154 void recalc_sigpending(void)
156 if (!recalc_sigpending_tsk(current) && !freezing(current))
157 clear_thread_flag(TIF_SIGPENDING);
161 /* Given the mask, find the first available signal that should be serviced. */
163 #define SYNCHRONOUS_MASK \
164 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
165 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
167 int next_signal(struct sigpending *pending, sigset_t *mask)
169 unsigned long i, *s, *m, x;
172 s = pending->signal.sig;
176 * Handle the first word specially: it contains the
177 * synchronous signals that need to be dequeued first.
181 if (x & SYNCHRONOUS_MASK)
182 x &= SYNCHRONOUS_MASK;
187 switch (_NSIG_WORDS) {
189 for (i = 1; i < _NSIG_WORDS; ++i) {
193 sig = ffz(~x) + i*_NSIG_BPW + 1;
202 sig = ffz(~x) + _NSIG_BPW + 1;
213 static inline void print_dropped_signal(int sig)
215 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
217 if (!print_fatal_signals)
220 if (!__ratelimit(&ratelimit_state))
223 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
224 current->comm, current->pid, sig);
228 * task_set_jobctl_pending - set jobctl pending bits
230 * @mask: pending bits to set
232 * Clear @mask from @task->jobctl. @mask must be subset of
233 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
234 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
235 * cleared. If @task is already being killed or exiting, this function
239 * Must be called with @task->sighand->siglock held.
242 * %true if @mask is set, %false if made noop because @task was dying.
244 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
246 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
247 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
248 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
250 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
253 if (mask & JOBCTL_STOP_SIGMASK)
254 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
256 task->jobctl |= mask;
261 * task_clear_jobctl_trapping - clear jobctl trapping bit
264 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
265 * Clear it and wake up the ptracer. Note that we don't need any further
266 * locking. @task->siglock guarantees that @task->parent points to the
270 * Must be called with @task->sighand->siglock held.
272 void task_clear_jobctl_trapping(struct task_struct *task)
274 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
275 task->jobctl &= ~JOBCTL_TRAPPING;
276 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
281 * task_clear_jobctl_pending - clear jobctl pending bits
283 * @mask: pending bits to clear
285 * Clear @mask from @task->jobctl. @mask must be subset of
286 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
287 * STOP bits are cleared together.
289 * If clearing of @mask leaves no stop or trap pending, this function calls
290 * task_clear_jobctl_trapping().
293 * Must be called with @task->sighand->siglock held.
295 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
297 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
299 if (mask & JOBCTL_STOP_PENDING)
300 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
302 task->jobctl &= ~mask;
304 if (!(task->jobctl & JOBCTL_PENDING_MASK))
305 task_clear_jobctl_trapping(task);
309 * task_participate_group_stop - participate in a group stop
310 * @task: task participating in a group stop
312 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
313 * Group stop states are cleared and the group stop count is consumed if
314 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
315 * stop, the appropriate %SIGNAL_* flags are set.
318 * Must be called with @task->sighand->siglock held.
321 * %true if group stop completion should be notified to the parent, %false
324 static bool task_participate_group_stop(struct task_struct *task)
326 struct signal_struct *sig = task->signal;
327 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
329 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
331 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
336 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
337 sig->group_stop_count--;
340 * Tell the caller to notify completion iff we are entering into a
341 * fresh group stop. Read comment in do_signal_stop() for details.
343 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
344 sig->flags = SIGNAL_STOP_STOPPED;
351 * allocate a new signal queue record
352 * - this may be called without locks if and only if t == current, otherwise an
353 * appropriate lock must be held to stop the target task from exiting
355 static struct sigqueue *
356 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
358 struct sigqueue *q = NULL;
359 struct user_struct *user;
362 * Protect access to @t credentials. This can go away when all
363 * callers hold rcu read lock.
366 user = get_uid(__task_cred(t)->user);
367 atomic_inc(&user->sigpending);
370 if (override_rlimit ||
371 atomic_read(&user->sigpending) <=
372 task_rlimit(t, RLIMIT_SIGPENDING)) {
373 q = kmem_cache_alloc(sigqueue_cachep, flags);
375 print_dropped_signal(sig);
378 if (unlikely(q == NULL)) {
379 atomic_dec(&user->sigpending);
382 INIT_LIST_HEAD(&q->list);
390 static void __sigqueue_free(struct sigqueue *q)
392 if (q->flags & SIGQUEUE_PREALLOC)
394 atomic_dec(&q->user->sigpending);
396 kmem_cache_free(sigqueue_cachep, q);
399 void flush_sigqueue(struct sigpending *queue)
403 sigemptyset(&queue->signal);
404 while (!list_empty(&queue->list)) {
405 q = list_entry(queue->list.next, struct sigqueue , list);
406 list_del_init(&q->list);
412 * Flush all pending signals for a task.
414 void __flush_signals(struct task_struct *t)
416 clear_tsk_thread_flag(t, TIF_SIGPENDING);
417 flush_sigqueue(&t->pending);
418 flush_sigqueue(&t->signal->shared_pending);
421 void flush_signals(struct task_struct *t)
425 spin_lock_irqsave(&t->sighand->siglock, flags);
427 spin_unlock_irqrestore(&t->sighand->siglock, flags);
430 static void __flush_itimer_signals(struct sigpending *pending)
432 sigset_t signal, retain;
433 struct sigqueue *q, *n;
435 signal = pending->signal;
436 sigemptyset(&retain);
438 list_for_each_entry_safe(q, n, &pending->list, list) {
439 int sig = q->info.si_signo;
441 if (likely(q->info.si_code != SI_TIMER)) {
442 sigaddset(&retain, sig);
444 sigdelset(&signal, sig);
445 list_del_init(&q->list);
450 sigorsets(&pending->signal, &signal, &retain);
453 void flush_itimer_signals(void)
455 struct task_struct *tsk = current;
458 spin_lock_irqsave(&tsk->sighand->siglock, flags);
459 __flush_itimer_signals(&tsk->pending);
460 __flush_itimer_signals(&tsk->signal->shared_pending);
461 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
464 void ignore_signals(struct task_struct *t)
468 for (i = 0; i < _NSIG; ++i)
469 t->sighand->action[i].sa.sa_handler = SIG_IGN;
475 * Flush all handlers for a task.
479 flush_signal_handlers(struct task_struct *t, int force_default)
482 struct k_sigaction *ka = &t->sighand->action[0];
483 for (i = _NSIG ; i != 0 ; i--) {
484 if (force_default || ka->sa.sa_handler != SIG_IGN)
485 ka->sa.sa_handler = SIG_DFL;
487 sigemptyset(&ka->sa.sa_mask);
492 int unhandled_signal(struct task_struct *tsk, int sig)
494 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
495 if (is_global_init(tsk))
497 if (handler != SIG_IGN && handler != SIG_DFL)
499 /* if ptraced, let the tracer determine */
504 * Notify the system that a driver wants to block all signals for this
505 * process, and wants to be notified if any signals at all were to be
506 * sent/acted upon. If the notifier routine returns non-zero, then the
507 * signal will be acted upon after all. If the notifier routine returns 0,
508 * then then signal will be blocked. Only one block per process is
509 * allowed. priv is a pointer to private data that the notifier routine
510 * can use to determine if the signal should be blocked or not.
513 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
517 spin_lock_irqsave(¤t->sighand->siglock, flags);
518 current->notifier_mask = mask;
519 current->notifier_data = priv;
520 current->notifier = notifier;
521 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
524 /* Notify the system that blocking has ended. */
527 unblock_all_signals(void)
531 spin_lock_irqsave(¤t->sighand->siglock, flags);
532 current->notifier = NULL;
533 current->notifier_data = NULL;
535 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
538 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
540 struct sigqueue *q, *first = NULL;
543 * Collect the siginfo appropriate to this signal. Check if
544 * there is another siginfo for the same signal.
546 list_for_each_entry(q, &list->list, list) {
547 if (q->info.si_signo == sig) {
554 sigdelset(&list->signal, sig);
558 list_del_init(&first->list);
559 copy_siginfo(info, &first->info);
560 __sigqueue_free(first);
563 * Ok, it wasn't in the queue. This must be
564 * a fast-pathed signal or we must have been
565 * out of queue space. So zero out the info.
567 info->si_signo = sig;
569 info->si_code = SI_USER;
575 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
578 int sig = next_signal(pending, mask);
581 if (current->notifier) {
582 if (sigismember(current->notifier_mask, sig)) {
583 if (!(current->notifier)(current->notifier_data)) {
584 clear_thread_flag(TIF_SIGPENDING);
590 collect_signal(sig, pending, info);
597 * Dequeue a signal and return the element to the caller, which is
598 * expected to free it.
600 * All callers have to hold the siglock.
602 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
606 /* We only dequeue private signals from ourselves, we don't let
607 * signalfd steal them
609 signr = __dequeue_signal(&tsk->pending, mask, info);
611 signr = __dequeue_signal(&tsk->signal->shared_pending,
616 * itimers are process shared and we restart periodic
617 * itimers in the signal delivery path to prevent DoS
618 * attacks in the high resolution timer case. This is
619 * compliant with the old way of self-restarting
620 * itimers, as the SIGALRM is a legacy signal and only
621 * queued once. Changing the restart behaviour to
622 * restart the timer in the signal dequeue path is
623 * reducing the timer noise on heavy loaded !highres
626 if (unlikely(signr == SIGALRM)) {
627 struct hrtimer *tmr = &tsk->signal->real_timer;
629 if (!hrtimer_is_queued(tmr) &&
630 tsk->signal->it_real_incr.tv64 != 0) {
631 hrtimer_forward(tmr, tmr->base->get_time(),
632 tsk->signal->it_real_incr);
633 hrtimer_restart(tmr);
642 if (unlikely(sig_kernel_stop(signr))) {
644 * Set a marker that we have dequeued a stop signal. Our
645 * caller might release the siglock and then the pending
646 * stop signal it is about to process is no longer in the
647 * pending bitmasks, but must still be cleared by a SIGCONT
648 * (and overruled by a SIGKILL). So those cases clear this
649 * shared flag after we've set it. Note that this flag may
650 * remain set after the signal we return is ignored or
651 * handled. That doesn't matter because its only purpose
652 * is to alert stop-signal processing code when another
653 * processor has come along and cleared the flag.
655 current->jobctl |= JOBCTL_STOP_DEQUEUED;
657 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
659 * Release the siglock to ensure proper locking order
660 * of timer locks outside of siglocks. Note, we leave
661 * irqs disabled here, since the posix-timers code is
662 * about to disable them again anyway.
664 spin_unlock(&tsk->sighand->siglock);
665 do_schedule_next_timer(info);
666 spin_lock(&tsk->sighand->siglock);
672 * Tell a process that it has a new active signal..
674 * NOTE! we rely on the previous spin_lock to
675 * lock interrupts for us! We can only be called with
676 * "siglock" held, and the local interrupt must
677 * have been disabled when that got acquired!
679 * No need to set need_resched since signal event passing
680 * goes through ->blocked
682 void signal_wake_up(struct task_struct *t, int resume)
686 set_tsk_thread_flag(t, TIF_SIGPENDING);
689 * For SIGKILL, we want to wake it up in the stopped/traced/killable
690 * case. We don't check t->state here because there is a race with it
691 * executing another processor and just now entering stopped state.
692 * By using wake_up_state, we ensure the process will wake up and
693 * handle its death signal.
695 mask = TASK_INTERRUPTIBLE;
697 mask |= TASK_WAKEKILL;
698 if (!wake_up_state(t, mask))
703 * Remove signals in mask from the pending set and queue.
704 * Returns 1 if any signals were found.
706 * All callers must be holding the siglock.
708 * This version takes a sigset mask and looks at all signals,
709 * not just those in the first mask word.
711 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
713 struct sigqueue *q, *n;
716 sigandsets(&m, mask, &s->signal);
717 if (sigisemptyset(&m))
720 sigandnsets(&s->signal, &s->signal, mask);
721 list_for_each_entry_safe(q, n, &s->list, list) {
722 if (sigismember(mask, q->info.si_signo)) {
723 list_del_init(&q->list);
730 * Remove signals in mask from the pending set and queue.
731 * Returns 1 if any signals were found.
733 * All callers must be holding the siglock.
735 static int rm_from_queue(unsigned long mask, struct sigpending *s)
737 struct sigqueue *q, *n;
739 if (!sigtestsetmask(&s->signal, mask))
742 sigdelsetmask(&s->signal, mask);
743 list_for_each_entry_safe(q, n, &s->list, list) {
744 if (q->info.si_signo < SIGRTMIN &&
745 (mask & sigmask(q->info.si_signo))) {
746 list_del_init(&q->list);
753 static inline int is_si_special(const struct siginfo *info)
755 return info <= SEND_SIG_FORCED;
758 static inline bool si_fromuser(const struct siginfo *info)
760 return info == SEND_SIG_NOINFO ||
761 (!is_si_special(info) && SI_FROMUSER(info));
765 * called with RCU read lock from check_kill_permission()
767 static int kill_ok_by_cred(struct task_struct *t)
769 const struct cred *cred = current_cred();
770 const struct cred *tcred = __task_cred(t);
772 if (uid_eq(cred->euid, tcred->suid) ||
773 uid_eq(cred->euid, tcred->uid) ||
774 uid_eq(cred->uid, tcred->suid) ||
775 uid_eq(cred->uid, tcred->uid))
778 if (ns_capable(tcred->user_ns, CAP_KILL))
785 * Bad permissions for sending the signal
786 * - the caller must hold the RCU read lock
788 static int check_kill_permission(int sig, struct siginfo *info,
789 struct task_struct *t)
794 if (!valid_signal(sig))
797 if (!si_fromuser(info))
800 error = audit_signal_info(sig, t); /* Let audit system see the signal */
804 if (!same_thread_group(current, t) &&
805 !kill_ok_by_cred(t)) {
808 sid = task_session(t);
810 * We don't return the error if sid == NULL. The
811 * task was unhashed, the caller must notice this.
813 if (!sid || sid == task_session(current))
820 return security_task_kill(t, info, sig, 0);
824 * ptrace_trap_notify - schedule trap to notify ptracer
825 * @t: tracee wanting to notify tracer
827 * This function schedules sticky ptrace trap which is cleared on the next
828 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
831 * If @t is running, STOP trap will be taken. If trapped for STOP and
832 * ptracer is listening for events, tracee is woken up so that it can
833 * re-trap for the new event. If trapped otherwise, STOP trap will be
834 * eventually taken without returning to userland after the existing traps
835 * are finished by PTRACE_CONT.
838 * Must be called with @task->sighand->siglock held.
840 static void ptrace_trap_notify(struct task_struct *t)
842 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
843 assert_spin_locked(&t->sighand->siglock);
845 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
846 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
850 * Handle magic process-wide effects of stop/continue signals. Unlike
851 * the signal actions, these happen immediately at signal-generation
852 * time regardless of blocking, ignoring, or handling. This does the
853 * actual continuing for SIGCONT, but not the actual stopping for stop
854 * signals. The process stop is done as a signal action for SIG_DFL.
856 * Returns true if the signal should be actually delivered, otherwise
857 * it should be dropped.
859 static int prepare_signal(int sig, struct task_struct *p, bool force)
861 struct signal_struct *signal = p->signal;
862 struct task_struct *t;
864 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
866 * The process is in the middle of dying, nothing to do.
868 } else if (sig_kernel_stop(sig)) {
870 * This is a stop signal. Remove SIGCONT from all queues.
872 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
875 rm_from_queue(sigmask(SIGCONT), &t->pending);
876 } while_each_thread(p, t);
877 } else if (sig == SIGCONT) {
880 * Remove all stop signals from all queues, wake all threads.
882 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
885 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
886 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
887 if (likely(!(t->ptrace & PT_SEIZED)))
888 wake_up_state(t, __TASK_STOPPED);
890 ptrace_trap_notify(t);
891 } while_each_thread(p, t);
894 * Notify the parent with CLD_CONTINUED if we were stopped.
896 * If we were in the middle of a group stop, we pretend it
897 * was already finished, and then continued. Since SIGCHLD
898 * doesn't queue we report only CLD_STOPPED, as if the next
899 * CLD_CONTINUED was dropped.
902 if (signal->flags & SIGNAL_STOP_STOPPED)
903 why |= SIGNAL_CLD_CONTINUED;
904 else if (signal->group_stop_count)
905 why |= SIGNAL_CLD_STOPPED;
909 * The first thread which returns from do_signal_stop()
910 * will take ->siglock, notice SIGNAL_CLD_MASK, and
911 * notify its parent. See get_signal_to_deliver().
913 signal->flags = why | SIGNAL_STOP_CONTINUED;
914 signal->group_stop_count = 0;
915 signal->group_exit_code = 0;
919 return !sig_ignored(p, sig, force);
923 * Test if P wants to take SIG. After we've checked all threads with this,
924 * it's equivalent to finding no threads not blocking SIG. Any threads not
925 * blocking SIG were ruled out because they are not running and already
926 * have pending signals. Such threads will dequeue from the shared queue
927 * as soon as they're available, so putting the signal on the shared queue
928 * will be equivalent to sending it to one such thread.
930 static inline int wants_signal(int sig, struct task_struct *p)
932 if (sigismember(&p->blocked, sig))
934 if (p->flags & PF_EXITING)
938 if (task_is_stopped_or_traced(p))
940 return task_curr(p) || !signal_pending(p);
943 static void complete_signal(int sig, struct task_struct *p, int group)
945 struct signal_struct *signal = p->signal;
946 struct task_struct *t;
949 * Now find a thread we can wake up to take the signal off the queue.
951 * If the main thread wants the signal, it gets first crack.
952 * Probably the least surprising to the average bear.
954 if (wants_signal(sig, p))
956 else if (!group || thread_group_empty(p))
958 * There is just one thread and it does not need to be woken.
959 * It will dequeue unblocked signals before it runs again.
964 * Otherwise try to find a suitable thread.
966 t = signal->curr_target;
967 while (!wants_signal(sig, t)) {
969 if (t == signal->curr_target)
971 * No thread needs to be woken.
972 * Any eligible threads will see
973 * the signal in the queue soon.
977 signal->curr_target = t;
981 * Found a killable thread. If the signal will be fatal,
982 * then start taking the whole group down immediately.
984 if (sig_fatal(p, sig) &&
985 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
986 !sigismember(&t->real_blocked, sig) &&
987 (sig == SIGKILL || !t->ptrace)) {
989 * This signal will be fatal to the whole group.
991 if (!sig_kernel_coredump(sig)) {
993 * Start a group exit and wake everybody up.
994 * This way we don't have other threads
995 * running and doing things after a slower
996 * thread has the fatal signal pending.
998 signal->flags = SIGNAL_GROUP_EXIT;
999 signal->group_exit_code = sig;
1000 signal->group_stop_count = 0;
1003 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1004 sigaddset(&t->pending.signal, SIGKILL);
1005 signal_wake_up(t, 1);
1006 } while_each_thread(p, t);
1012 * The signal is already in the shared-pending queue.
1013 * Tell the chosen thread to wake up and dequeue it.
1015 signal_wake_up(t, sig == SIGKILL);
1019 static inline int legacy_queue(struct sigpending *signals, int sig)
1021 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1024 #ifdef CONFIG_USER_NS
1025 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1027 if (current_user_ns() == task_cred_xxx(t, user_ns))
1030 if (SI_FROMKERNEL(info))
1034 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1035 make_kuid(current_user_ns(), info->si_uid));
1039 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1045 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1046 int group, int from_ancestor_ns)
1048 struct sigpending *pending;
1050 int override_rlimit;
1051 int ret = 0, result;
1053 assert_spin_locked(&t->sighand->siglock);
1055 result = TRACE_SIGNAL_IGNORED;
1056 if (!prepare_signal(sig, t,
1057 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1060 pending = group ? &t->signal->shared_pending : &t->pending;
1062 * Short-circuit ignored signals and support queuing
1063 * exactly one non-rt signal, so that we can get more
1064 * detailed information about the cause of the signal.
1066 result = TRACE_SIGNAL_ALREADY_PENDING;
1067 if (legacy_queue(pending, sig))
1070 result = TRACE_SIGNAL_DELIVERED;
1072 * fast-pathed signals for kernel-internal things like SIGSTOP
1075 if (info == SEND_SIG_FORCED)
1079 * Real-time signals must be queued if sent by sigqueue, or
1080 * some other real-time mechanism. It is implementation
1081 * defined whether kill() does so. We attempt to do so, on
1082 * the principle of least surprise, but since kill is not
1083 * allowed to fail with EAGAIN when low on memory we just
1084 * make sure at least one signal gets delivered and don't
1085 * pass on the info struct.
1088 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1090 override_rlimit = 0;
1092 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1095 list_add_tail(&q->list, &pending->list);
1096 switch ((unsigned long) info) {
1097 case (unsigned long) SEND_SIG_NOINFO:
1098 q->info.si_signo = sig;
1099 q->info.si_errno = 0;
1100 q->info.si_code = SI_USER;
1101 q->info.si_pid = task_tgid_nr_ns(current,
1102 task_active_pid_ns(t));
1103 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1105 case (unsigned long) SEND_SIG_PRIV:
1106 q->info.si_signo = sig;
1107 q->info.si_errno = 0;
1108 q->info.si_code = SI_KERNEL;
1113 copy_siginfo(&q->info, info);
1114 if (from_ancestor_ns)
1119 userns_fixup_signal_uid(&q->info, t);
1121 } else if (!is_si_special(info)) {
1122 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1124 * Queue overflow, abort. We may abort if the
1125 * signal was rt and sent by user using something
1126 * other than kill().
1128 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1133 * This is a silent loss of information. We still
1134 * send the signal, but the *info bits are lost.
1136 result = TRACE_SIGNAL_LOSE_INFO;
1141 signalfd_notify(t, sig);
1142 sigaddset(&pending->signal, sig);
1143 complete_signal(sig, t, group);
1145 trace_signal_generate(sig, info, t, group, result);
1149 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1152 int from_ancestor_ns = 0;
1154 #ifdef CONFIG_PID_NS
1155 from_ancestor_ns = si_fromuser(info) &&
1156 !task_pid_nr_ns(current, task_active_pid_ns(t));
1159 return __send_signal(sig, info, t, group, from_ancestor_ns);
1162 static void print_fatal_signal(int signr)
1164 struct pt_regs *regs = signal_pt_regs();
1165 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1166 current->comm, task_pid_nr(current), signr);
1168 #if defined(__i386__) && !defined(__arch_um__)
1169 printk("code at %08lx: ", regs->ip);
1172 for (i = 0; i < 16; i++) {
1175 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1177 printk("%02x ", insn);
1187 static int __init setup_print_fatal_signals(char *str)
1189 get_option (&str, &print_fatal_signals);
1194 __setup("print-fatal-signals=", setup_print_fatal_signals);
1197 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1199 return send_signal(sig, info, p, 1);
1203 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1205 return send_signal(sig, info, t, 0);
1208 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1211 unsigned long flags;
1214 if (lock_task_sighand(p, &flags)) {
1215 ret = send_signal(sig, info, p, group);
1216 unlock_task_sighand(p, &flags);
1223 * Force a signal that the process can't ignore: if necessary
1224 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1226 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1227 * since we do not want to have a signal handler that was blocked
1228 * be invoked when user space had explicitly blocked it.
1230 * We don't want to have recursive SIGSEGV's etc, for example,
1231 * that is why we also clear SIGNAL_UNKILLABLE.
1234 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1236 unsigned long int flags;
1237 int ret, blocked, ignored;
1238 struct k_sigaction *action;
1240 spin_lock_irqsave(&t->sighand->siglock, flags);
1241 action = &t->sighand->action[sig-1];
1242 ignored = action->sa.sa_handler == SIG_IGN;
1243 blocked = sigismember(&t->blocked, sig);
1244 if (blocked || ignored) {
1245 action->sa.sa_handler = SIG_DFL;
1247 sigdelset(&t->blocked, sig);
1248 recalc_sigpending_and_wake(t);
1251 if (action->sa.sa_handler == SIG_DFL)
1252 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1253 ret = specific_send_sig_info(sig, info, t);
1254 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1260 * Nuke all other threads in the group.
1262 int zap_other_threads(struct task_struct *p)
1264 struct task_struct *t = p;
1267 p->signal->group_stop_count = 0;
1269 while_each_thread(p, t) {
1270 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1273 /* Don't bother with already dead threads */
1276 sigaddset(&t->pending.signal, SIGKILL);
1277 signal_wake_up(t, 1);
1283 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1284 unsigned long *flags)
1286 struct sighand_struct *sighand;
1289 local_irq_save(*flags);
1291 sighand = rcu_dereference(tsk->sighand);
1292 if (unlikely(sighand == NULL)) {
1294 local_irq_restore(*flags);
1298 spin_lock(&sighand->siglock);
1299 if (likely(sighand == tsk->sighand)) {
1303 spin_unlock(&sighand->siglock);
1305 local_irq_restore(*flags);
1312 * send signal info to all the members of a group
1314 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1319 ret = check_kill_permission(sig, info, p);
1323 ret = do_send_sig_info(sig, info, p, true);
1329 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1330 * control characters do (^C, ^Z etc)
1331 * - the caller must hold at least a readlock on tasklist_lock
1333 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1335 struct task_struct *p = NULL;
1336 int retval, success;
1340 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1341 int err = group_send_sig_info(sig, info, p);
1344 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1345 return success ? 0 : retval;
1348 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1351 struct task_struct *p;
1355 p = pid_task(pid, PIDTYPE_PID);
1357 error = group_send_sig_info(sig, info, p);
1358 if (unlikely(error == -ESRCH))
1360 * The task was unhashed in between, try again.
1361 * If it is dead, pid_task() will return NULL,
1362 * if we race with de_thread() it will find the
1372 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1376 error = kill_pid_info(sig, info, find_vpid(pid));
1381 static int kill_as_cred_perm(const struct cred *cred,
1382 struct task_struct *target)
1384 const struct cred *pcred = __task_cred(target);
1385 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1386 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1391 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1392 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1393 const struct cred *cred, u32 secid)
1396 struct task_struct *p;
1397 unsigned long flags;
1399 if (!valid_signal(sig))
1403 p = pid_task(pid, PIDTYPE_PID);
1408 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1412 ret = security_task_kill(p, info, sig, secid);
1417 if (lock_task_sighand(p, &flags)) {
1418 ret = __send_signal(sig, info, p, 1, 0);
1419 unlock_task_sighand(p, &flags);
1427 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1430 * kill_something_info() interprets pid in interesting ways just like kill(2).
1432 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1433 * is probably wrong. Should make it like BSD or SYSV.
1436 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1442 ret = kill_pid_info(sig, info, find_vpid(pid));
1447 read_lock(&tasklist_lock);
1449 ret = __kill_pgrp_info(sig, info,
1450 pid ? find_vpid(-pid) : task_pgrp(current));
1452 int retval = 0, count = 0;
1453 struct task_struct * p;
1455 for_each_process(p) {
1456 if (task_pid_vnr(p) > 1 &&
1457 !same_thread_group(p, current)) {
1458 int err = group_send_sig_info(sig, info, p);
1464 ret = count ? retval : -ESRCH;
1466 read_unlock(&tasklist_lock);
1472 * These are for backward compatibility with the rest of the kernel source.
1475 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1478 * Make sure legacy kernel users don't send in bad values
1479 * (normal paths check this in check_kill_permission).
1481 if (!valid_signal(sig))
1484 return do_send_sig_info(sig, info, p, false);
1487 #define __si_special(priv) \
1488 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1491 send_sig(int sig, struct task_struct *p, int priv)
1493 return send_sig_info(sig, __si_special(priv), p);
1497 force_sig(int sig, struct task_struct *p)
1499 force_sig_info(sig, SEND_SIG_PRIV, p);
1503 * When things go south during signal handling, we
1504 * will force a SIGSEGV. And if the signal that caused
1505 * the problem was already a SIGSEGV, we'll want to
1506 * make sure we don't even try to deliver the signal..
1509 force_sigsegv(int sig, struct task_struct *p)
1511 if (sig == SIGSEGV) {
1512 unsigned long flags;
1513 spin_lock_irqsave(&p->sighand->siglock, flags);
1514 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1515 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1517 force_sig(SIGSEGV, p);
1521 int kill_pgrp(struct pid *pid, int sig, int priv)
1525 read_lock(&tasklist_lock);
1526 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1527 read_unlock(&tasklist_lock);
1531 EXPORT_SYMBOL(kill_pgrp);
1533 int kill_pid(struct pid *pid, int sig, int priv)
1535 return kill_pid_info(sig, __si_special(priv), pid);
1537 EXPORT_SYMBOL(kill_pid);
1540 * These functions support sending signals using preallocated sigqueue
1541 * structures. This is needed "because realtime applications cannot
1542 * afford to lose notifications of asynchronous events, like timer
1543 * expirations or I/O completions". In the case of POSIX Timers
1544 * we allocate the sigqueue structure from the timer_create. If this
1545 * allocation fails we are able to report the failure to the application
1546 * with an EAGAIN error.
1548 struct sigqueue *sigqueue_alloc(void)
1550 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1553 q->flags |= SIGQUEUE_PREALLOC;
1558 void sigqueue_free(struct sigqueue *q)
1560 unsigned long flags;
1561 spinlock_t *lock = ¤t->sighand->siglock;
1563 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1565 * We must hold ->siglock while testing q->list
1566 * to serialize with collect_signal() or with
1567 * __exit_signal()->flush_sigqueue().
1569 spin_lock_irqsave(lock, flags);
1570 q->flags &= ~SIGQUEUE_PREALLOC;
1572 * If it is queued it will be freed when dequeued,
1573 * like the "regular" sigqueue.
1575 if (!list_empty(&q->list))
1577 spin_unlock_irqrestore(lock, flags);
1583 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1585 int sig = q->info.si_signo;
1586 struct sigpending *pending;
1587 unsigned long flags;
1590 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1593 if (!likely(lock_task_sighand(t, &flags)))
1596 ret = 1; /* the signal is ignored */
1597 result = TRACE_SIGNAL_IGNORED;
1598 if (!prepare_signal(sig, t, false))
1602 if (unlikely(!list_empty(&q->list))) {
1604 * If an SI_TIMER entry is already queue just increment
1605 * the overrun count.
1607 BUG_ON(q->info.si_code != SI_TIMER);
1608 q->info.si_overrun++;
1609 result = TRACE_SIGNAL_ALREADY_PENDING;
1612 q->info.si_overrun = 0;
1614 signalfd_notify(t, sig);
1615 pending = group ? &t->signal->shared_pending : &t->pending;
1616 list_add_tail(&q->list, &pending->list);
1617 sigaddset(&pending->signal, sig);
1618 complete_signal(sig, t, group);
1619 result = TRACE_SIGNAL_DELIVERED;
1621 trace_signal_generate(sig, &q->info, t, group, result);
1622 unlock_task_sighand(t, &flags);
1628 * Let a parent know about the death of a child.
1629 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1631 * Returns true if our parent ignored us and so we've switched to
1634 bool do_notify_parent(struct task_struct *tsk, int sig)
1636 struct siginfo info;
1637 unsigned long flags;
1638 struct sighand_struct *psig;
1639 bool autoreap = false;
1643 /* do_notify_parent_cldstop should have been called instead. */
1644 BUG_ON(task_is_stopped_or_traced(tsk));
1646 BUG_ON(!tsk->ptrace &&
1647 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1649 if (sig != SIGCHLD) {
1651 * This is only possible if parent == real_parent.
1652 * Check if it has changed security domain.
1654 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1658 info.si_signo = sig;
1661 * We are under tasklist_lock here so our parent is tied to
1662 * us and cannot change.
1664 * task_active_pid_ns will always return the same pid namespace
1665 * until a task passes through release_task.
1667 * write_lock() currently calls preempt_disable() which is the
1668 * same as rcu_read_lock(), but according to Oleg, this is not
1669 * correct to rely on this
1672 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1673 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1677 info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
1678 info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
1680 info.si_status = tsk->exit_code & 0x7f;
1681 if (tsk->exit_code & 0x80)
1682 info.si_code = CLD_DUMPED;
1683 else if (tsk->exit_code & 0x7f)
1684 info.si_code = CLD_KILLED;
1686 info.si_code = CLD_EXITED;
1687 info.si_status = tsk->exit_code >> 8;
1690 psig = tsk->parent->sighand;
1691 spin_lock_irqsave(&psig->siglock, flags);
1692 if (!tsk->ptrace && sig == SIGCHLD &&
1693 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1694 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1696 * We are exiting and our parent doesn't care. POSIX.1
1697 * defines special semantics for setting SIGCHLD to SIG_IGN
1698 * or setting the SA_NOCLDWAIT flag: we should be reaped
1699 * automatically and not left for our parent's wait4 call.
1700 * Rather than having the parent do it as a magic kind of
1701 * signal handler, we just set this to tell do_exit that we
1702 * can be cleaned up without becoming a zombie. Note that
1703 * we still call __wake_up_parent in this case, because a
1704 * blocked sys_wait4 might now return -ECHILD.
1706 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1707 * is implementation-defined: we do (if you don't want
1708 * it, just use SIG_IGN instead).
1711 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1714 if (valid_signal(sig) && sig)
1715 __group_send_sig_info(sig, &info, tsk->parent);
1716 __wake_up_parent(tsk, tsk->parent);
1717 spin_unlock_irqrestore(&psig->siglock, flags);
1723 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1724 * @tsk: task reporting the state change
1725 * @for_ptracer: the notification is for ptracer
1726 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1728 * Notify @tsk's parent that the stopped/continued state has changed. If
1729 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1730 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1733 * Must be called with tasklist_lock at least read locked.
1735 static void do_notify_parent_cldstop(struct task_struct *tsk,
1736 bool for_ptracer, int why)
1738 struct siginfo info;
1739 unsigned long flags;
1740 struct task_struct *parent;
1741 struct sighand_struct *sighand;
1744 parent = tsk->parent;
1746 tsk = tsk->group_leader;
1747 parent = tsk->real_parent;
1750 info.si_signo = SIGCHLD;
1753 * see comment in do_notify_parent() about the following 4 lines
1756 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1757 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1760 info.si_utime = cputime_to_clock_t(tsk->utime);
1761 info.si_stime = cputime_to_clock_t(tsk->stime);
1766 info.si_status = SIGCONT;
1769 info.si_status = tsk->signal->group_exit_code & 0x7f;
1772 info.si_status = tsk->exit_code & 0x7f;
1778 sighand = parent->sighand;
1779 spin_lock_irqsave(&sighand->siglock, flags);
1780 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1781 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1782 __group_send_sig_info(SIGCHLD, &info, parent);
1784 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1786 __wake_up_parent(tsk, parent);
1787 spin_unlock_irqrestore(&sighand->siglock, flags);
1790 static inline int may_ptrace_stop(void)
1792 if (!likely(current->ptrace))
1795 * Are we in the middle of do_coredump?
1796 * If so and our tracer is also part of the coredump stopping
1797 * is a deadlock situation, and pointless because our tracer
1798 * is dead so don't allow us to stop.
1799 * If SIGKILL was already sent before the caller unlocked
1800 * ->siglock we must see ->core_state != NULL. Otherwise it
1801 * is safe to enter schedule().
1803 if (unlikely(current->mm->core_state) &&
1804 unlikely(current->mm == current->parent->mm))
1811 * Return non-zero if there is a SIGKILL that should be waking us up.
1812 * Called with the siglock held.
1814 static int sigkill_pending(struct task_struct *tsk)
1816 return sigismember(&tsk->pending.signal, SIGKILL) ||
1817 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1821 * This must be called with current->sighand->siglock held.
1823 * This should be the path for all ptrace stops.
1824 * We always set current->last_siginfo while stopped here.
1825 * That makes it a way to test a stopped process for
1826 * being ptrace-stopped vs being job-control-stopped.
1828 * If we actually decide not to stop at all because the tracer
1829 * is gone, we keep current->exit_code unless clear_code.
1831 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1832 __releases(¤t->sighand->siglock)
1833 __acquires(¤t->sighand->siglock)
1835 bool gstop_done = false;
1837 if (arch_ptrace_stop_needed(exit_code, info)) {
1839 * The arch code has something special to do before a
1840 * ptrace stop. This is allowed to block, e.g. for faults
1841 * on user stack pages. We can't keep the siglock while
1842 * calling arch_ptrace_stop, so we must release it now.
1843 * To preserve proper semantics, we must do this before
1844 * any signal bookkeeping like checking group_stop_count.
1845 * Meanwhile, a SIGKILL could come in before we retake the
1846 * siglock. That must prevent us from sleeping in TASK_TRACED.
1847 * So after regaining the lock, we must check for SIGKILL.
1849 spin_unlock_irq(¤t->sighand->siglock);
1850 arch_ptrace_stop(exit_code, info);
1851 spin_lock_irq(¤t->sighand->siglock);
1852 if (sigkill_pending(current))
1857 * We're committing to trapping. TRACED should be visible before
1858 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1859 * Also, transition to TRACED and updates to ->jobctl should be
1860 * atomic with respect to siglock and should be done after the arch
1861 * hook as siglock is released and regrabbed across it.
1863 set_current_state(TASK_TRACED);
1865 current->last_siginfo = info;
1866 current->exit_code = exit_code;
1869 * If @why is CLD_STOPPED, we're trapping to participate in a group
1870 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1871 * across siglock relocks since INTERRUPT was scheduled, PENDING
1872 * could be clear now. We act as if SIGCONT is received after
1873 * TASK_TRACED is entered - ignore it.
1875 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1876 gstop_done = task_participate_group_stop(current);
1878 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1879 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1880 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1881 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1883 /* entering a trap, clear TRAPPING */
1884 task_clear_jobctl_trapping(current);
1886 spin_unlock_irq(¤t->sighand->siglock);
1887 read_lock(&tasklist_lock);
1888 if (may_ptrace_stop()) {
1890 * Notify parents of the stop.
1892 * While ptraced, there are two parents - the ptracer and
1893 * the real_parent of the group_leader. The ptracer should
1894 * know about every stop while the real parent is only
1895 * interested in the completion of group stop. The states
1896 * for the two don't interact with each other. Notify
1897 * separately unless they're gonna be duplicates.
1899 do_notify_parent_cldstop(current, true, why);
1900 if (gstop_done && ptrace_reparented(current))
1901 do_notify_parent_cldstop(current, false, why);
1904 * Don't want to allow preemption here, because
1905 * sys_ptrace() needs this task to be inactive.
1907 * XXX: implement read_unlock_no_resched().
1910 read_unlock(&tasklist_lock);
1911 preempt_enable_no_resched();
1915 * By the time we got the lock, our tracer went away.
1916 * Don't drop the lock yet, another tracer may come.
1918 * If @gstop_done, the ptracer went away between group stop
1919 * completion and here. During detach, it would have set
1920 * JOBCTL_STOP_PENDING on us and we'll re-enter
1921 * TASK_STOPPED in do_signal_stop() on return, so notifying
1922 * the real parent of the group stop completion is enough.
1925 do_notify_parent_cldstop(current, false, why);
1927 __set_current_state(TASK_RUNNING);
1929 current->exit_code = 0;
1930 read_unlock(&tasklist_lock);
1934 * While in TASK_TRACED, we were considered "frozen enough".
1935 * Now that we woke up, it's crucial if we're supposed to be
1936 * frozen that we freeze now before running anything substantial.
1941 * We are back. Now reacquire the siglock before touching
1942 * last_siginfo, so that we are sure to have synchronized with
1943 * any signal-sending on another CPU that wants to examine it.
1945 spin_lock_irq(¤t->sighand->siglock);
1946 current->last_siginfo = NULL;
1948 /* LISTENING can be set only during STOP traps, clear it */
1949 current->jobctl &= ~JOBCTL_LISTENING;
1952 * Queued signals ignored us while we were stopped for tracing.
1953 * So check for any that we should take before resuming user mode.
1954 * This sets TIF_SIGPENDING, but never clears it.
1956 recalc_sigpending_tsk(current);
1959 static void ptrace_do_notify(int signr, int exit_code, int why)
1963 memset(&info, 0, sizeof info);
1964 info.si_signo = signr;
1965 info.si_code = exit_code;
1966 info.si_pid = task_pid_vnr(current);
1967 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1969 /* Let the debugger run. */
1970 ptrace_stop(exit_code, why, 1, &info);
1973 void ptrace_notify(int exit_code)
1975 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1976 if (unlikely(current->task_works))
1979 spin_lock_irq(¤t->sighand->siglock);
1980 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1981 spin_unlock_irq(¤t->sighand->siglock);
1985 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1986 * @signr: signr causing group stop if initiating
1988 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1989 * and participate in it. If already set, participate in the existing
1990 * group stop. If participated in a group stop (and thus slept), %true is
1991 * returned with siglock released.
1993 * If ptraced, this function doesn't handle stop itself. Instead,
1994 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1995 * untouched. The caller must ensure that INTERRUPT trap handling takes
1996 * places afterwards.
1999 * Must be called with @current->sighand->siglock held, which is released
2003 * %false if group stop is already cancelled or ptrace trap is scheduled.
2004 * %true if participated in group stop.
2006 static bool do_signal_stop(int signr)
2007 __releases(¤t->sighand->siglock)
2009 struct signal_struct *sig = current->signal;
2011 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2012 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2013 struct task_struct *t;
2015 /* signr will be recorded in task->jobctl for retries */
2016 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2018 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2019 unlikely(signal_group_exit(sig)))
2022 * There is no group stop already in progress. We must
2025 * While ptraced, a task may be resumed while group stop is
2026 * still in effect and then receive a stop signal and
2027 * initiate another group stop. This deviates from the
2028 * usual behavior as two consecutive stop signals can't
2029 * cause two group stops when !ptraced. That is why we
2030 * also check !task_is_stopped(t) below.
2032 * The condition can be distinguished by testing whether
2033 * SIGNAL_STOP_STOPPED is already set. Don't generate
2034 * group_exit_code in such case.
2036 * This is not necessary for SIGNAL_STOP_CONTINUED because
2037 * an intervening stop signal is required to cause two
2038 * continued events regardless of ptrace.
2040 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2041 sig->group_exit_code = signr;
2043 sig->group_stop_count = 0;
2045 if (task_set_jobctl_pending(current, signr | gstop))
2046 sig->group_stop_count++;
2048 for (t = next_thread(current); t != current;
2049 t = next_thread(t)) {
2051 * Setting state to TASK_STOPPED for a group
2052 * stop is always done with the siglock held,
2053 * so this check has no races.
2055 if (!task_is_stopped(t) &&
2056 task_set_jobctl_pending(t, signr | gstop)) {
2057 sig->group_stop_count++;
2058 if (likely(!(t->ptrace & PT_SEIZED)))
2059 signal_wake_up(t, 0);
2061 ptrace_trap_notify(t);
2066 if (likely(!current->ptrace)) {
2070 * If there are no other threads in the group, or if there
2071 * is a group stop in progress and we are the last to stop,
2072 * report to the parent.
2074 if (task_participate_group_stop(current))
2075 notify = CLD_STOPPED;
2077 __set_current_state(TASK_STOPPED);
2078 spin_unlock_irq(¤t->sighand->siglock);
2081 * Notify the parent of the group stop completion. Because
2082 * we're not holding either the siglock or tasklist_lock
2083 * here, ptracer may attach inbetween; however, this is for
2084 * group stop and should always be delivered to the real
2085 * parent of the group leader. The new ptracer will get
2086 * its notification when this task transitions into
2090 read_lock(&tasklist_lock);
2091 do_notify_parent_cldstop(current, false, notify);
2092 read_unlock(&tasklist_lock);
2095 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2100 * While ptraced, group stop is handled by STOP trap.
2101 * Schedule it and let the caller deal with it.
2103 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2109 * do_jobctl_trap - take care of ptrace jobctl traps
2111 * When PT_SEIZED, it's used for both group stop and explicit
2112 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2113 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2114 * the stop signal; otherwise, %SIGTRAP.
2116 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2117 * number as exit_code and no siginfo.
2120 * Must be called with @current->sighand->siglock held, which may be
2121 * released and re-acquired before returning with intervening sleep.
2123 static void do_jobctl_trap(void)
2125 struct signal_struct *signal = current->signal;
2126 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2128 if (current->ptrace & PT_SEIZED) {
2129 if (!signal->group_stop_count &&
2130 !(signal->flags & SIGNAL_STOP_STOPPED))
2132 WARN_ON_ONCE(!signr);
2133 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2136 WARN_ON_ONCE(!signr);
2137 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2138 current->exit_code = 0;
2142 static int ptrace_signal(int signr, siginfo_t *info)
2144 ptrace_signal_deliver();
2146 * We do not check sig_kernel_stop(signr) but set this marker
2147 * unconditionally because we do not know whether debugger will
2148 * change signr. This flag has no meaning unless we are going
2149 * to stop after return from ptrace_stop(). In this case it will
2150 * be checked in do_signal_stop(), we should only stop if it was
2151 * not cleared by SIGCONT while we were sleeping. See also the
2152 * comment in dequeue_signal().
2154 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2155 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2157 /* We're back. Did the debugger cancel the sig? */
2158 signr = current->exit_code;
2162 current->exit_code = 0;
2165 * Update the siginfo structure if the signal has
2166 * changed. If the debugger wanted something
2167 * specific in the siginfo structure then it should
2168 * have updated *info via PTRACE_SETSIGINFO.
2170 if (signr != info->si_signo) {
2171 info->si_signo = signr;
2173 info->si_code = SI_USER;
2175 info->si_pid = task_pid_vnr(current->parent);
2176 info->si_uid = from_kuid_munged(current_user_ns(),
2177 task_uid(current->parent));
2181 /* If the (new) signal is now blocked, requeue it. */
2182 if (sigismember(¤t->blocked, signr)) {
2183 specific_send_sig_info(signr, info, current);
2190 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2191 struct pt_regs *regs, void *cookie)
2193 struct sighand_struct *sighand = current->sighand;
2194 struct signal_struct *signal = current->signal;
2197 if (unlikely(current->task_works))
2200 if (unlikely(uprobe_deny_signal()))
2205 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2206 * While in TASK_STOPPED, we were considered "frozen enough".
2207 * Now that we woke up, it's crucial if we're supposed to be
2208 * frozen that we freeze now before running anything substantial.
2212 spin_lock_irq(&sighand->siglock);
2214 * Every stopped thread goes here after wakeup. Check to see if
2215 * we should notify the parent, prepare_signal(SIGCONT) encodes
2216 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2218 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2221 if (signal->flags & SIGNAL_CLD_CONTINUED)
2222 why = CLD_CONTINUED;
2226 signal->flags &= ~SIGNAL_CLD_MASK;
2228 spin_unlock_irq(&sighand->siglock);
2231 * Notify the parent that we're continuing. This event is
2232 * always per-process and doesn't make whole lot of sense
2233 * for ptracers, who shouldn't consume the state via
2234 * wait(2) either, but, for backward compatibility, notify
2235 * the ptracer of the group leader too unless it's gonna be
2238 read_lock(&tasklist_lock);
2239 do_notify_parent_cldstop(current, false, why);
2241 if (ptrace_reparented(current->group_leader))
2242 do_notify_parent_cldstop(current->group_leader,
2244 read_unlock(&tasklist_lock);
2250 struct k_sigaction *ka;
2252 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2256 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2258 spin_unlock_irq(&sighand->siglock);
2262 signr = dequeue_signal(current, ¤t->blocked, info);
2265 break; /* will return 0 */
2267 if (unlikely(current->ptrace) && signr != SIGKILL) {
2268 signr = ptrace_signal(signr, info);
2273 ka = &sighand->action[signr-1];
2275 /* Trace actually delivered signals. */
2276 trace_signal_deliver(signr, info, ka);
2278 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2280 if (ka->sa.sa_handler != SIG_DFL) {
2281 /* Run the handler. */
2284 if (ka->sa.sa_flags & SA_ONESHOT)
2285 ka->sa.sa_handler = SIG_DFL;
2287 break; /* will return non-zero "signr" value */
2291 * Now we are doing the default action for this signal.
2293 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2297 * Global init gets no signals it doesn't want.
2298 * Container-init gets no signals it doesn't want from same
2301 * Note that if global/container-init sees a sig_kernel_only()
2302 * signal here, the signal must have been generated internally
2303 * or must have come from an ancestor namespace. In either
2304 * case, the signal cannot be dropped.
2306 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2307 !sig_kernel_only(signr))
2310 if (sig_kernel_stop(signr)) {
2312 * The default action is to stop all threads in
2313 * the thread group. The job control signals
2314 * do nothing in an orphaned pgrp, but SIGSTOP
2315 * always works. Note that siglock needs to be
2316 * dropped during the call to is_orphaned_pgrp()
2317 * because of lock ordering with tasklist_lock.
2318 * This allows an intervening SIGCONT to be posted.
2319 * We need to check for that and bail out if necessary.
2321 if (signr != SIGSTOP) {
2322 spin_unlock_irq(&sighand->siglock);
2324 /* signals can be posted during this window */
2326 if (is_current_pgrp_orphaned())
2329 spin_lock_irq(&sighand->siglock);
2332 if (likely(do_signal_stop(info->si_signo))) {
2333 /* It released the siglock. */
2338 * We didn't actually stop, due to a race
2339 * with SIGCONT or something like that.
2344 spin_unlock_irq(&sighand->siglock);
2347 * Anything else is fatal, maybe with a core dump.
2349 current->flags |= PF_SIGNALED;
2351 if (sig_kernel_coredump(signr)) {
2352 if (print_fatal_signals)
2353 print_fatal_signal(info->si_signo);
2355 * If it was able to dump core, this kills all
2356 * other threads in the group and synchronizes with
2357 * their demise. If we lost the race with another
2358 * thread getting here, it set group_exit_code
2359 * first and our do_group_exit call below will use
2360 * that value and ignore the one we pass it.
2366 * Death signals, no core dump.
2368 do_group_exit(info->si_signo);
2371 spin_unlock_irq(&sighand->siglock);
2376 * signal_delivered -
2377 * @sig: number of signal being delivered
2378 * @info: siginfo_t of signal being delivered
2379 * @ka: sigaction setting that chose the handler
2380 * @regs: user register state
2381 * @stepping: nonzero if debugger single-step or block-step in use
2383 * This function should be called when a signal has succesfully been
2384 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2385 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2386 * is set in @ka->sa.sa_flags. Tracing is notified.
2388 void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2389 struct pt_regs *regs, int stepping)
2393 /* A signal was successfully delivered, and the
2394 saved sigmask was stored on the signal frame,
2395 and will be restored by sigreturn. So we can
2396 simply clear the restore sigmask flag. */
2397 clear_restore_sigmask();
2399 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2400 if (!(ka->sa.sa_flags & SA_NODEFER))
2401 sigaddset(&blocked, sig);
2402 set_current_blocked(&blocked);
2403 tracehook_signal_handler(sig, info, ka, regs, stepping);
2407 * It could be that complete_signal() picked us to notify about the
2408 * group-wide signal. Other threads should be notified now to take
2409 * the shared signals in @which since we will not.
2411 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2414 struct task_struct *t;
2416 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2417 if (sigisemptyset(&retarget))
2421 while_each_thread(tsk, t) {
2422 if (t->flags & PF_EXITING)
2425 if (!has_pending_signals(&retarget, &t->blocked))
2427 /* Remove the signals this thread can handle. */
2428 sigandsets(&retarget, &retarget, &t->blocked);
2430 if (!signal_pending(t))
2431 signal_wake_up(t, 0);
2433 if (sigisemptyset(&retarget))
2438 void exit_signals(struct task_struct *tsk)
2444 * @tsk is about to have PF_EXITING set - lock out users which
2445 * expect stable threadgroup.
2447 threadgroup_change_begin(tsk);
2449 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2450 tsk->flags |= PF_EXITING;
2451 threadgroup_change_end(tsk);
2455 spin_lock_irq(&tsk->sighand->siglock);
2457 * From now this task is not visible for group-wide signals,
2458 * see wants_signal(), do_signal_stop().
2460 tsk->flags |= PF_EXITING;
2462 threadgroup_change_end(tsk);
2464 if (!signal_pending(tsk))
2467 unblocked = tsk->blocked;
2468 signotset(&unblocked);
2469 retarget_shared_pending(tsk, &unblocked);
2471 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2472 task_participate_group_stop(tsk))
2473 group_stop = CLD_STOPPED;
2475 spin_unlock_irq(&tsk->sighand->siglock);
2478 * If group stop has completed, deliver the notification. This
2479 * should always go to the real parent of the group leader.
2481 if (unlikely(group_stop)) {
2482 read_lock(&tasklist_lock);
2483 do_notify_parent_cldstop(tsk, false, group_stop);
2484 read_unlock(&tasklist_lock);
2488 EXPORT_SYMBOL(recalc_sigpending);
2489 EXPORT_SYMBOL_GPL(dequeue_signal);
2490 EXPORT_SYMBOL(flush_signals);
2491 EXPORT_SYMBOL(force_sig);
2492 EXPORT_SYMBOL(send_sig);
2493 EXPORT_SYMBOL(send_sig_info);
2494 EXPORT_SYMBOL(sigprocmask);
2495 EXPORT_SYMBOL(block_all_signals);
2496 EXPORT_SYMBOL(unblock_all_signals);
2500 * System call entry points.
2504 * sys_restart_syscall - restart a system call
2506 SYSCALL_DEFINE0(restart_syscall)
2508 struct restart_block *restart = ¤t_thread_info()->restart_block;
2509 return restart->fn(restart);
2512 long do_no_restart_syscall(struct restart_block *param)
2517 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2519 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2520 sigset_t newblocked;
2521 /* A set of now blocked but previously unblocked signals. */
2522 sigandnsets(&newblocked, newset, ¤t->blocked);
2523 retarget_shared_pending(tsk, &newblocked);
2525 tsk->blocked = *newset;
2526 recalc_sigpending();
2530 * set_current_blocked - change current->blocked mask
2533 * It is wrong to change ->blocked directly, this helper should be used
2534 * to ensure the process can't miss a shared signal we are going to block.
2536 void set_current_blocked(sigset_t *newset)
2538 struct task_struct *tsk = current;
2539 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2540 spin_lock_irq(&tsk->sighand->siglock);
2541 __set_task_blocked(tsk, newset);
2542 spin_unlock_irq(&tsk->sighand->siglock);
2545 void __set_current_blocked(const sigset_t *newset)
2547 struct task_struct *tsk = current;
2549 spin_lock_irq(&tsk->sighand->siglock);
2550 __set_task_blocked(tsk, newset);
2551 spin_unlock_irq(&tsk->sighand->siglock);
2555 * This is also useful for kernel threads that want to temporarily
2556 * (or permanently) block certain signals.
2558 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2559 * interface happily blocks "unblockable" signals like SIGKILL
2562 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2564 struct task_struct *tsk = current;
2567 /* Lockless, only current can change ->blocked, never from irq */
2569 *oldset = tsk->blocked;
2573 sigorsets(&newset, &tsk->blocked, set);
2576 sigandnsets(&newset, &tsk->blocked, set);
2585 __set_current_blocked(&newset);
2590 * sys_rt_sigprocmask - change the list of currently blocked signals
2591 * @how: whether to add, remove, or set signals
2592 * @nset: stores pending signals
2593 * @oset: previous value of signal mask if non-null
2594 * @sigsetsize: size of sigset_t type
2596 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2597 sigset_t __user *, oset, size_t, sigsetsize)
2599 sigset_t old_set, new_set;
2602 /* XXX: Don't preclude handling different sized sigset_t's. */
2603 if (sigsetsize != sizeof(sigset_t))
2606 old_set = current->blocked;
2609 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2611 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2613 error = sigprocmask(how, &new_set, NULL);
2619 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2626 long do_sigpending(void __user *set, unsigned long sigsetsize)
2628 long error = -EINVAL;
2631 if (sigsetsize > sizeof(sigset_t))
2634 spin_lock_irq(¤t->sighand->siglock);
2635 sigorsets(&pending, ¤t->pending.signal,
2636 ¤t->signal->shared_pending.signal);
2637 spin_unlock_irq(¤t->sighand->siglock);
2639 /* Outside the lock because only this thread touches it. */
2640 sigandsets(&pending, ¤t->blocked, &pending);
2643 if (!copy_to_user(set, &pending, sigsetsize))
2651 * sys_rt_sigpending - examine a pending signal that has been raised
2653 * @set: stores pending signals
2654 * @sigsetsize: size of sigset_t type or larger
2656 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2658 return do_sigpending(set, sigsetsize);
2661 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2663 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2667 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2669 if (from->si_code < 0)
2670 return __copy_to_user(to, from, sizeof(siginfo_t))
2673 * If you change siginfo_t structure, please be sure
2674 * this code is fixed accordingly.
2675 * Please remember to update the signalfd_copyinfo() function
2676 * inside fs/signalfd.c too, in case siginfo_t changes.
2677 * It should never copy any pad contained in the structure
2678 * to avoid security leaks, but must copy the generic
2679 * 3 ints plus the relevant union member.
2681 err = __put_user(from->si_signo, &to->si_signo);
2682 err |= __put_user(from->si_errno, &to->si_errno);
2683 err |= __put_user((short)from->si_code, &to->si_code);
2684 switch (from->si_code & __SI_MASK) {
2686 err |= __put_user(from->si_pid, &to->si_pid);
2687 err |= __put_user(from->si_uid, &to->si_uid);
2690 err |= __put_user(from->si_tid, &to->si_tid);
2691 err |= __put_user(from->si_overrun, &to->si_overrun);
2692 err |= __put_user(from->si_ptr, &to->si_ptr);
2695 err |= __put_user(from->si_band, &to->si_band);
2696 err |= __put_user(from->si_fd, &to->si_fd);
2699 err |= __put_user(from->si_addr, &to->si_addr);
2700 #ifdef __ARCH_SI_TRAPNO
2701 err |= __put_user(from->si_trapno, &to->si_trapno);
2703 #ifdef BUS_MCEERR_AO
2705 * Other callers might not initialize the si_lsb field,
2706 * so check explicitly for the right codes here.
2708 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2709 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2713 err |= __put_user(from->si_pid, &to->si_pid);
2714 err |= __put_user(from->si_uid, &to->si_uid);
2715 err |= __put_user(from->si_status, &to->si_status);
2716 err |= __put_user(from->si_utime, &to->si_utime);
2717 err |= __put_user(from->si_stime, &to->si_stime);
2719 case __SI_RT: /* This is not generated by the kernel as of now. */
2720 case __SI_MESGQ: /* But this is */
2721 err |= __put_user(from->si_pid, &to->si_pid);
2722 err |= __put_user(from->si_uid, &to->si_uid);
2723 err |= __put_user(from->si_ptr, &to->si_ptr);
2725 #ifdef __ARCH_SIGSYS
2727 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2728 err |= __put_user(from->si_syscall, &to->si_syscall);
2729 err |= __put_user(from->si_arch, &to->si_arch);
2732 default: /* this is just in case for now ... */
2733 err |= __put_user(from->si_pid, &to->si_pid);
2734 err |= __put_user(from->si_uid, &to->si_uid);
2743 * do_sigtimedwait - wait for queued signals specified in @which
2744 * @which: queued signals to wait for
2745 * @info: if non-null, the signal's siginfo is returned here
2746 * @ts: upper bound on process time suspension
2748 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2749 const struct timespec *ts)
2751 struct task_struct *tsk = current;
2752 long timeout = MAX_SCHEDULE_TIMEOUT;
2753 sigset_t mask = *which;
2757 if (!timespec_valid(ts))
2759 timeout = timespec_to_jiffies(ts);
2761 * We can be close to the next tick, add another one
2762 * to ensure we will wait at least the time asked for.
2764 if (ts->tv_sec || ts->tv_nsec)
2769 * Invert the set of allowed signals to get those we want to block.
2771 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2774 spin_lock_irq(&tsk->sighand->siglock);
2775 sig = dequeue_signal(tsk, &mask, info);
2776 if (!sig && timeout) {
2778 * None ready, temporarily unblock those we're interested
2779 * while we are sleeping in so that we'll be awakened when
2780 * they arrive. Unblocking is always fine, we can avoid
2781 * set_current_blocked().
2783 tsk->real_blocked = tsk->blocked;
2784 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2785 recalc_sigpending();
2786 spin_unlock_irq(&tsk->sighand->siglock);
2788 timeout = schedule_timeout_interruptible(timeout);
2790 spin_lock_irq(&tsk->sighand->siglock);
2791 __set_task_blocked(tsk, &tsk->real_blocked);
2792 siginitset(&tsk->real_blocked, 0);
2793 sig = dequeue_signal(tsk, &mask, info);
2795 spin_unlock_irq(&tsk->sighand->siglock);
2799 return timeout ? -EINTR : -EAGAIN;
2803 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2805 * @uthese: queued signals to wait for
2806 * @uinfo: if non-null, the signal's siginfo is returned here
2807 * @uts: upper bound on process time suspension
2808 * @sigsetsize: size of sigset_t type
2810 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2811 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2819 /* XXX: Don't preclude handling different sized sigset_t's. */
2820 if (sigsetsize != sizeof(sigset_t))
2823 if (copy_from_user(&these, uthese, sizeof(these)))
2827 if (copy_from_user(&ts, uts, sizeof(ts)))
2831 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2833 if (ret > 0 && uinfo) {
2834 if (copy_siginfo_to_user(uinfo, &info))
2842 * sys_kill - send a signal to a process
2843 * @pid: the PID of the process
2844 * @sig: signal to be sent
2846 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2848 struct siginfo info;
2850 info.si_signo = sig;
2852 info.si_code = SI_USER;
2853 info.si_pid = task_tgid_vnr(current);
2854 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2856 return kill_something_info(sig, &info, pid);
2860 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2862 struct task_struct *p;
2866 p = find_task_by_vpid(pid);
2867 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2868 error = check_kill_permission(sig, info, p);
2870 * The null signal is a permissions and process existence
2871 * probe. No signal is actually delivered.
2873 if (!error && sig) {
2874 error = do_send_sig_info(sig, info, p, false);
2876 * If lock_task_sighand() failed we pretend the task
2877 * dies after receiving the signal. The window is tiny,
2878 * and the signal is private anyway.
2880 if (unlikely(error == -ESRCH))
2889 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2891 struct siginfo info;
2893 info.si_signo = sig;
2895 info.si_code = SI_TKILL;
2896 info.si_pid = task_tgid_vnr(current);
2897 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2899 return do_send_specific(tgid, pid, sig, &info);
2903 * sys_tgkill - send signal to one specific thread
2904 * @tgid: the thread group ID of the thread
2905 * @pid: the PID of the thread
2906 * @sig: signal to be sent
2908 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2909 * exists but it's not belonging to the target process anymore. This
2910 * method solves the problem of threads exiting and PIDs getting reused.
2912 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2914 /* This is only valid for single tasks */
2915 if (pid <= 0 || tgid <= 0)
2918 return do_tkill(tgid, pid, sig);
2922 * sys_tkill - send signal to one specific task
2923 * @pid: the PID of the task
2924 * @sig: signal to be sent
2926 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2928 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2930 /* This is only valid for single tasks */
2934 return do_tkill(0, pid, sig);
2938 * sys_rt_sigqueueinfo - send signal information to a signal
2939 * @pid: the PID of the thread
2940 * @sig: signal to be sent
2941 * @uinfo: signal info to be sent
2943 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2944 siginfo_t __user *, uinfo)
2948 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2951 /* Not even root can pretend to send signals from the kernel.
2952 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2954 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2955 /* We used to allow any < 0 si_code */
2956 WARN_ON_ONCE(info.si_code < 0);
2959 info.si_signo = sig;
2961 /* POSIX.1b doesn't mention process groups. */
2962 return kill_proc_info(sig, &info, pid);
2965 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2967 /* This is only valid for single tasks */
2968 if (pid <= 0 || tgid <= 0)
2971 /* Not even root can pretend to send signals from the kernel.
2972 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2974 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2975 /* We used to allow any < 0 si_code */
2976 WARN_ON_ONCE(info->si_code < 0);
2979 info->si_signo = sig;
2981 return do_send_specific(tgid, pid, sig, info);
2984 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2985 siginfo_t __user *, uinfo)
2989 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2992 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2995 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2997 struct task_struct *t = current;
2998 struct k_sigaction *k;
3001 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3004 k = &t->sighand->action[sig-1];
3006 spin_lock_irq(¤t->sighand->siglock);
3011 sigdelsetmask(&act->sa.sa_mask,
3012 sigmask(SIGKILL) | sigmask(SIGSTOP));
3016 * "Setting a signal action to SIG_IGN for a signal that is
3017 * pending shall cause the pending signal to be discarded,
3018 * whether or not it is blocked."
3020 * "Setting a signal action to SIG_DFL for a signal that is
3021 * pending and whose default action is to ignore the signal
3022 * (for example, SIGCHLD), shall cause the pending signal to
3023 * be discarded, whether or not it is blocked"
3025 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3027 sigaddset(&mask, sig);
3028 rm_from_queue_full(&mask, &t->signal->shared_pending);
3030 rm_from_queue_full(&mask, &t->pending);
3032 } while (t != current);
3036 spin_unlock_irq(¤t->sighand->siglock);
3041 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3046 oss.ss_sp = (void __user *) current->sas_ss_sp;
3047 oss.ss_size = current->sas_ss_size;
3048 oss.ss_flags = sas_ss_flags(sp);
3056 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3058 error = __get_user(ss_sp, &uss->ss_sp) |
3059 __get_user(ss_flags, &uss->ss_flags) |
3060 __get_user(ss_size, &uss->ss_size);
3065 if (on_sig_stack(sp))
3070 * Note - this code used to test ss_flags incorrectly:
3071 * old code may have been written using ss_flags==0
3072 * to mean ss_flags==SS_ONSTACK (as this was the only
3073 * way that worked) - this fix preserves that older
3076 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3079 if (ss_flags == SS_DISABLE) {
3084 if (ss_size < MINSIGSTKSZ)
3088 current->sas_ss_sp = (unsigned long) ss_sp;
3089 current->sas_ss_size = ss_size;
3095 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3097 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3098 __put_user(oss.ss_size, &uoss->ss_size) |
3099 __put_user(oss.ss_flags, &uoss->ss_flags);
3106 int restore_altstack(const stack_t __user *uss)
3108 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3109 /* squash all but EFAULT for now */
3110 return err == -EFAULT ? err : 0;
3113 #ifdef __ARCH_WANT_SYS_SIGPENDING
3116 * sys_sigpending - examine pending signals
3117 * @set: where mask of pending signal is returned
3119 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3121 return do_sigpending(set, sizeof(*set));
3126 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3128 * sys_sigprocmask - examine and change blocked signals
3129 * @how: whether to add, remove, or set signals
3130 * @nset: signals to add or remove (if non-null)
3131 * @oset: previous value of signal mask if non-null
3133 * Some platforms have their own version with special arguments;
3134 * others support only sys_rt_sigprocmask.
3137 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3138 old_sigset_t __user *, oset)
3140 old_sigset_t old_set, new_set;
3141 sigset_t new_blocked;
3143 old_set = current->blocked.sig[0];
3146 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3148 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3150 new_blocked = current->blocked;
3154 sigaddsetmask(&new_blocked, new_set);
3157 sigdelsetmask(&new_blocked, new_set);
3160 new_blocked.sig[0] = new_set;
3166 __set_current_blocked(&new_blocked);
3170 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3176 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3178 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3180 * sys_rt_sigaction - alter an action taken by a process
3181 * @sig: signal to be sent
3182 * @act: new sigaction
3183 * @oact: used to save the previous sigaction
3184 * @sigsetsize: size of sigset_t type
3186 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3187 const struct sigaction __user *, act,
3188 struct sigaction __user *, oact,
3191 struct k_sigaction new_sa, old_sa;
3194 /* XXX: Don't preclude handling different sized sigset_t's. */
3195 if (sigsetsize != sizeof(sigset_t))
3199 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3203 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3206 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3212 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3214 #ifdef __ARCH_WANT_SYS_SGETMASK
3217 * For backwards compatibility. Functionality superseded by sigprocmask.
3219 SYSCALL_DEFINE0(sgetmask)
3222 return current->blocked.sig[0];
3225 SYSCALL_DEFINE1(ssetmask, int, newmask)
3227 int old = current->blocked.sig[0];
3230 set_current_blocked(&newset);
3234 #endif /* __ARCH_WANT_SGETMASK */
3236 #ifdef __ARCH_WANT_SYS_SIGNAL
3238 * For backwards compatibility. Functionality superseded by sigaction.
3240 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3242 struct k_sigaction new_sa, old_sa;
3245 new_sa.sa.sa_handler = handler;
3246 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3247 sigemptyset(&new_sa.sa.sa_mask);
3249 ret = do_sigaction(sig, &new_sa, &old_sa);
3251 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3253 #endif /* __ARCH_WANT_SYS_SIGNAL */
3255 #ifdef __ARCH_WANT_SYS_PAUSE
3257 SYSCALL_DEFINE0(pause)
3259 while (!signal_pending(current)) {
3260 current->state = TASK_INTERRUPTIBLE;
3263 return -ERESTARTNOHAND;
3268 int sigsuspend(sigset_t *set)
3270 current->saved_sigmask = current->blocked;
3271 set_current_blocked(set);
3273 current->state = TASK_INTERRUPTIBLE;
3275 set_restore_sigmask();
3276 return -ERESTARTNOHAND;
3279 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3281 * sys_rt_sigsuspend - replace the signal mask for a value with the
3282 * @unewset value until a signal is received
3283 * @unewset: new signal mask value
3284 * @sigsetsize: size of sigset_t type
3286 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3290 /* XXX: Don't preclude handling different sized sigset_t's. */
3291 if (sigsetsize != sizeof(sigset_t))
3294 if (copy_from_user(&newset, unewset, sizeof(newset)))
3296 return sigsuspend(&newset);
3298 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3300 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3305 void __init signals_init(void)
3307 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3310 #ifdef CONFIG_KGDB_KDB
3311 #include <linux/kdb.h>
3313 * kdb_send_sig_info - Allows kdb to send signals without exposing
3314 * signal internals. This function checks if the required locks are
3315 * available before calling the main signal code, to avoid kdb
3319 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3321 static struct task_struct *kdb_prev_t;
3323 if (!spin_trylock(&t->sighand->siglock)) {
3324 kdb_printf("Can't do kill command now.\n"
3325 "The sigmask lock is held somewhere else in "
3326 "kernel, try again later\n");
3329 spin_unlock(&t->sighand->siglock);
3330 new_t = kdb_prev_t != t;
3332 if (t->state != TASK_RUNNING && new_t) {
3333 kdb_printf("Process is not RUNNING, sending a signal from "
3334 "kdb risks deadlock\n"
3335 "on the run queue locks. "
3336 "The signal has _not_ been sent.\n"
3337 "Reissue the kill command if you want to risk "
3341 sig = info->si_signo;
3342 if (send_sig_info(sig, info, t))
3343 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3346 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3348 #endif /* CONFIG_KGDB_KDB */