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/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/ratelimit.h>
26 #include <linux/tracehook.h>
27 #include <linux/capability.h>
28 #include <linux/freezer.h>
29 #include <linux/pid_namespace.h>
30 #include <linux/nsproxy.h>
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/signal.h>
34 #include <asm/param.h>
35 #include <asm/uaccess.h>
36 #include <asm/unistd.h>
37 #include <asm/siginfo.h>
38 #include "audit.h" /* audit_signal_info() */
41 * SLAB caches for signal bits.
44 static struct kmem_cache *sigqueue_cachep;
46 int print_fatal_signals __read_mostly;
48 static void __user *sig_handler(struct task_struct *t, int sig)
50 return t->sighand->action[sig - 1].sa.sa_handler;
53 static int sig_handler_ignored(void __user *handler, int sig)
55 /* Is it explicitly or implicitly ignored? */
56 return handler == SIG_IGN ||
57 (handler == SIG_DFL && sig_kernel_ignore(sig));
60 static int sig_task_ignored(struct task_struct *t, int sig,
65 handler = sig_handler(t, sig);
67 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
68 handler == SIG_DFL && !from_ancestor_ns)
71 return sig_handler_ignored(handler, sig);
74 static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
77 * Blocked signals are never ignored, since the
78 * signal handler may change by the time it is
81 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
84 if (!sig_task_ignored(t, sig, from_ancestor_ns))
88 * Tracers may want to know about even ignored signals.
90 return !tracehook_consider_ignored_signal(t, sig);
94 * Re-calculate pending state from the set of locally pending
95 * signals, globally pending signals, and blocked signals.
97 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
102 switch (_NSIG_WORDS) {
104 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
105 ready |= signal->sig[i] &~ blocked->sig[i];
108 case 4: ready = signal->sig[3] &~ blocked->sig[3];
109 ready |= signal->sig[2] &~ blocked->sig[2];
110 ready |= signal->sig[1] &~ blocked->sig[1];
111 ready |= signal->sig[0] &~ blocked->sig[0];
114 case 2: ready = signal->sig[1] &~ blocked->sig[1];
115 ready |= signal->sig[0] &~ blocked->sig[0];
118 case 1: ready = signal->sig[0] &~ blocked->sig[0];
123 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
125 static int recalc_sigpending_tsk(struct task_struct *t)
127 if (t->signal->group_stop_count > 0 ||
128 PENDING(&t->pending, &t->blocked) ||
129 PENDING(&t->signal->shared_pending, &t->blocked)) {
130 set_tsk_thread_flag(t, TIF_SIGPENDING);
134 * We must never clear the flag in another thread, or in current
135 * when it's possible the current syscall is returning -ERESTART*.
136 * So we don't clear it here, and only callers who know they should do.
142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
143 * This is superfluous when called on current, the wakeup is a harmless no-op.
145 void recalc_sigpending_and_wake(struct task_struct *t)
147 if (recalc_sigpending_tsk(t))
148 signal_wake_up(t, 0);
151 void recalc_sigpending(void)
153 if (unlikely(tracehook_force_sigpending()))
154 set_thread_flag(TIF_SIGPENDING);
155 else if (!recalc_sigpending_tsk(current) && !freezing(current))
156 clear_thread_flag(TIF_SIGPENDING);
160 /* Given the mask, find the first available signal that should be serviced. */
162 int next_signal(struct sigpending *pending, sigset_t *mask)
164 unsigned long i, *s, *m, x;
167 s = pending->signal.sig;
169 switch (_NSIG_WORDS) {
171 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
172 if ((x = *s &~ *m) != 0) {
173 sig = ffz(~x) + i*_NSIG_BPW + 1;
178 case 2: if ((x = s[0] &~ m[0]) != 0)
180 else if ((x = s[1] &~ m[1]) != 0)
187 case 1: if ((x = *s &~ *m) != 0)
195 static inline void print_dropped_signal(int sig)
197 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
199 if (!print_fatal_signals)
202 if (!__ratelimit(&ratelimit_state))
205 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
206 current->comm, current->pid, sig);
210 * allocate a new signal queue record
211 * - this may be called without locks if and only if t == current, otherwise an
212 * appopriate lock must be held to stop the target task from exiting
214 static struct sigqueue *
215 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
217 struct sigqueue *q = NULL;
218 struct user_struct *user;
221 * Protect access to @t credentials. This can go away when all
222 * callers hold rcu read lock.
225 user = get_uid(__task_cred(t)->user);
226 atomic_inc(&user->sigpending);
229 if (override_rlimit ||
230 atomic_read(&user->sigpending) <=
231 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur) {
232 q = kmem_cache_alloc(sigqueue_cachep, flags);
234 print_dropped_signal(sig);
237 if (unlikely(q == NULL)) {
238 atomic_dec(&user->sigpending);
241 INIT_LIST_HEAD(&q->list);
249 static void __sigqueue_free(struct sigqueue *q)
251 if (q->flags & SIGQUEUE_PREALLOC)
253 atomic_dec(&q->user->sigpending);
255 kmem_cache_free(sigqueue_cachep, q);
258 void flush_sigqueue(struct sigpending *queue)
262 sigemptyset(&queue->signal);
263 while (!list_empty(&queue->list)) {
264 q = list_entry(queue->list.next, struct sigqueue , list);
265 list_del_init(&q->list);
271 * Flush all pending signals for a task.
273 void __flush_signals(struct task_struct *t)
275 clear_tsk_thread_flag(t, TIF_SIGPENDING);
276 flush_sigqueue(&t->pending);
277 flush_sigqueue(&t->signal->shared_pending);
280 void flush_signals(struct task_struct *t)
284 spin_lock_irqsave(&t->sighand->siglock, flags);
286 spin_unlock_irqrestore(&t->sighand->siglock, flags);
289 static void __flush_itimer_signals(struct sigpending *pending)
291 sigset_t signal, retain;
292 struct sigqueue *q, *n;
294 signal = pending->signal;
295 sigemptyset(&retain);
297 list_for_each_entry_safe(q, n, &pending->list, list) {
298 int sig = q->info.si_signo;
300 if (likely(q->info.si_code != SI_TIMER)) {
301 sigaddset(&retain, sig);
303 sigdelset(&signal, sig);
304 list_del_init(&q->list);
309 sigorsets(&pending->signal, &signal, &retain);
312 void flush_itimer_signals(void)
314 struct task_struct *tsk = current;
317 spin_lock_irqsave(&tsk->sighand->siglock, flags);
318 __flush_itimer_signals(&tsk->pending);
319 __flush_itimer_signals(&tsk->signal->shared_pending);
320 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
323 void ignore_signals(struct task_struct *t)
327 for (i = 0; i < _NSIG; ++i)
328 t->sighand->action[i].sa.sa_handler = SIG_IGN;
334 * Flush all handlers for a task.
338 flush_signal_handlers(struct task_struct *t, int force_default)
341 struct k_sigaction *ka = &t->sighand->action[0];
342 for (i = _NSIG ; i != 0 ; i--) {
343 if (force_default || ka->sa.sa_handler != SIG_IGN)
344 ka->sa.sa_handler = SIG_DFL;
346 sigemptyset(&ka->sa.sa_mask);
351 int unhandled_signal(struct task_struct *tsk, int sig)
353 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
354 if (is_global_init(tsk))
356 if (handler != SIG_IGN && handler != SIG_DFL)
358 return !tracehook_consider_fatal_signal(tsk, sig);
362 /* Notify the system that a driver wants to block all signals for this
363 * process, and wants to be notified if any signals at all were to be
364 * sent/acted upon. If the notifier routine returns non-zero, then the
365 * signal will be acted upon after all. If the notifier routine returns 0,
366 * then then signal will be blocked. Only one block per process is
367 * allowed. priv is a pointer to private data that the notifier routine
368 * can use to determine if the signal should be blocked or not. */
371 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
375 spin_lock_irqsave(¤t->sighand->siglock, flags);
376 current->notifier_mask = mask;
377 current->notifier_data = priv;
378 current->notifier = notifier;
379 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
382 /* Notify the system that blocking has ended. */
385 unblock_all_signals(void)
389 spin_lock_irqsave(¤t->sighand->siglock, flags);
390 current->notifier = NULL;
391 current->notifier_data = NULL;
393 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
396 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
398 struct sigqueue *q, *first = NULL;
401 * Collect the siginfo appropriate to this signal. Check if
402 * there is another siginfo for the same signal.
404 list_for_each_entry(q, &list->list, list) {
405 if (q->info.si_signo == sig) {
412 sigdelset(&list->signal, sig);
416 list_del_init(&first->list);
417 copy_siginfo(info, &first->info);
418 __sigqueue_free(first);
420 /* Ok, it wasn't in the queue. This must be
421 a fast-pathed signal or we must have been
422 out of queue space. So zero out the info.
424 info->si_signo = sig;
426 info->si_code = SI_USER;
432 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
435 int sig = next_signal(pending, mask);
438 if (current->notifier) {
439 if (sigismember(current->notifier_mask, sig)) {
440 if (!(current->notifier)(current->notifier_data)) {
441 clear_thread_flag(TIF_SIGPENDING);
447 collect_signal(sig, pending, info);
454 * Dequeue a signal and return the element to the caller, which is
455 * expected to free it.
457 * All callers have to hold the siglock.
459 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
463 /* We only dequeue private signals from ourselves, we don't let
464 * signalfd steal them
466 signr = __dequeue_signal(&tsk->pending, mask, info);
468 signr = __dequeue_signal(&tsk->signal->shared_pending,
473 * itimers are process shared and we restart periodic
474 * itimers in the signal delivery path to prevent DoS
475 * attacks in the high resolution timer case. This is
476 * compliant with the old way of self restarting
477 * itimers, as the SIGALRM is a legacy signal and only
478 * queued once. Changing the restart behaviour to
479 * restart the timer in the signal dequeue path is
480 * reducing the timer noise on heavy loaded !highres
483 if (unlikely(signr == SIGALRM)) {
484 struct hrtimer *tmr = &tsk->signal->real_timer;
486 if (!hrtimer_is_queued(tmr) &&
487 tsk->signal->it_real_incr.tv64 != 0) {
488 hrtimer_forward(tmr, tmr->base->get_time(),
489 tsk->signal->it_real_incr);
490 hrtimer_restart(tmr);
499 if (unlikely(sig_kernel_stop(signr))) {
501 * Set a marker that we have dequeued a stop signal. Our
502 * caller might release the siglock and then the pending
503 * stop signal it is about to process is no longer in the
504 * pending bitmasks, but must still be cleared by a SIGCONT
505 * (and overruled by a SIGKILL). So those cases clear this
506 * shared flag after we've set it. Note that this flag may
507 * remain set after the signal we return is ignored or
508 * handled. That doesn't matter because its only purpose
509 * is to alert stop-signal processing code when another
510 * processor has come along and cleared the flag.
512 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
514 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
516 * Release the siglock to ensure proper locking order
517 * of timer locks outside of siglocks. Note, we leave
518 * irqs disabled here, since the posix-timers code is
519 * about to disable them again anyway.
521 spin_unlock(&tsk->sighand->siglock);
522 do_schedule_next_timer(info);
523 spin_lock(&tsk->sighand->siglock);
529 * Tell a process that it has a new active signal..
531 * NOTE! we rely on the previous spin_lock to
532 * lock interrupts for us! We can only be called with
533 * "siglock" held, and the local interrupt must
534 * have been disabled when that got acquired!
536 * No need to set need_resched since signal event passing
537 * goes through ->blocked
539 void signal_wake_up(struct task_struct *t, int resume)
543 set_tsk_thread_flag(t, TIF_SIGPENDING);
546 * For SIGKILL, we want to wake it up in the stopped/traced/killable
547 * case. We don't check t->state here because there is a race with it
548 * executing another processor and just now entering stopped state.
549 * By using wake_up_state, we ensure the process will wake up and
550 * handle its death signal.
552 mask = TASK_INTERRUPTIBLE;
554 mask |= TASK_WAKEKILL;
555 if (!wake_up_state(t, mask))
560 * Remove signals in mask from the pending set and queue.
561 * Returns 1 if any signals were found.
563 * All callers must be holding the siglock.
565 * This version takes a sigset mask and looks at all signals,
566 * not just those in the first mask word.
568 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
570 struct sigqueue *q, *n;
573 sigandsets(&m, mask, &s->signal);
574 if (sigisemptyset(&m))
577 signandsets(&s->signal, &s->signal, mask);
578 list_for_each_entry_safe(q, n, &s->list, list) {
579 if (sigismember(mask, q->info.si_signo)) {
580 list_del_init(&q->list);
587 * Remove signals in mask from the pending set and queue.
588 * Returns 1 if any signals were found.
590 * All callers must be holding the siglock.
592 static int rm_from_queue(unsigned long mask, struct sigpending *s)
594 struct sigqueue *q, *n;
596 if (!sigtestsetmask(&s->signal, mask))
599 sigdelsetmask(&s->signal, mask);
600 list_for_each_entry_safe(q, n, &s->list, list) {
601 if (q->info.si_signo < SIGRTMIN &&
602 (mask & sigmask(q->info.si_signo))) {
603 list_del_init(&q->list);
610 static inline int is_si_special(const struct siginfo *info)
612 return info <= SEND_SIG_FORCED;
615 static inline bool si_fromuser(const struct siginfo *info)
617 return info == SEND_SIG_NOINFO ||
618 (!is_si_special(info) && SI_FROMUSER(info));
622 * Bad permissions for sending the signal
623 * - the caller must hold at least the RCU read lock
625 static int check_kill_permission(int sig, struct siginfo *info,
626 struct task_struct *t)
628 const struct cred *cred, *tcred;
632 if (!valid_signal(sig))
635 if (!si_fromuser(info))
638 error = audit_signal_info(sig, t); /* Let audit system see the signal */
642 cred = current_cred();
643 tcred = __task_cred(t);
644 if (!same_thread_group(current, t) &&
645 (cred->euid ^ tcred->suid) &&
646 (cred->euid ^ tcred->uid) &&
647 (cred->uid ^ tcred->suid) &&
648 (cred->uid ^ tcred->uid) &&
649 !capable(CAP_KILL)) {
652 sid = task_session(t);
654 * We don't return the error if sid == NULL. The
655 * task was unhashed, the caller must notice this.
657 if (!sid || sid == task_session(current))
664 return security_task_kill(t, info, sig, 0);
668 * Handle magic process-wide effects of stop/continue signals. Unlike
669 * the signal actions, these happen immediately at signal-generation
670 * time regardless of blocking, ignoring, or handling. This does the
671 * actual continuing for SIGCONT, but not the actual stopping for stop
672 * signals. The process stop is done as a signal action for SIG_DFL.
674 * Returns true if the signal should be actually delivered, otherwise
675 * it should be dropped.
677 static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
679 struct signal_struct *signal = p->signal;
680 struct task_struct *t;
682 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
684 * The process is in the middle of dying, nothing to do.
686 } else if (sig_kernel_stop(sig)) {
688 * This is a stop signal. Remove SIGCONT from all queues.
690 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
693 rm_from_queue(sigmask(SIGCONT), &t->pending);
694 } while_each_thread(p, t);
695 } else if (sig == SIGCONT) {
698 * Remove all stop signals from all queues,
699 * and wake all threads.
701 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
705 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
707 * If there is a handler for SIGCONT, we must make
708 * sure that no thread returns to user mode before
709 * we post the signal, in case it was the only
710 * thread eligible to run the signal handler--then
711 * it must not do anything between resuming and
712 * running the handler. With the TIF_SIGPENDING
713 * flag set, the thread will pause and acquire the
714 * siglock that we hold now and until we've queued
715 * the pending signal.
717 * Wake up the stopped thread _after_ setting
720 state = __TASK_STOPPED;
721 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
722 set_tsk_thread_flag(t, TIF_SIGPENDING);
723 state |= TASK_INTERRUPTIBLE;
725 wake_up_state(t, state);
726 } while_each_thread(p, t);
729 * Notify the parent with CLD_CONTINUED if we were stopped.
731 * If we were in the middle of a group stop, we pretend it
732 * was already finished, and then continued. Since SIGCHLD
733 * doesn't queue we report only CLD_STOPPED, as if the next
734 * CLD_CONTINUED was dropped.
737 if (signal->flags & SIGNAL_STOP_STOPPED)
738 why |= SIGNAL_CLD_CONTINUED;
739 else if (signal->group_stop_count)
740 why |= SIGNAL_CLD_STOPPED;
744 * The first thread which returns from do_signal_stop()
745 * will take ->siglock, notice SIGNAL_CLD_MASK, and
746 * notify its parent. See get_signal_to_deliver().
748 signal->flags = why | SIGNAL_STOP_CONTINUED;
749 signal->group_stop_count = 0;
750 signal->group_exit_code = 0;
753 * We are not stopped, but there could be a stop
754 * signal in the middle of being processed after
755 * being removed from the queue. Clear that too.
757 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
761 return !sig_ignored(p, sig, from_ancestor_ns);
765 * Test if P wants to take SIG. After we've checked all threads with this,
766 * it's equivalent to finding no threads not blocking SIG. Any threads not
767 * blocking SIG were ruled out because they are not running and already
768 * have pending signals. Such threads will dequeue from the shared queue
769 * as soon as they're available, so putting the signal on the shared queue
770 * will be equivalent to sending it to one such thread.
772 static inline int wants_signal(int sig, struct task_struct *p)
774 if (sigismember(&p->blocked, sig))
776 if (p->flags & PF_EXITING)
780 if (task_is_stopped_or_traced(p))
782 return task_curr(p) || !signal_pending(p);
785 static void complete_signal(int sig, struct task_struct *p, int group)
787 struct signal_struct *signal = p->signal;
788 struct task_struct *t;
791 * Now find a thread we can wake up to take the signal off the queue.
793 * If the main thread wants the signal, it gets first crack.
794 * Probably the least surprising to the average bear.
796 if (wants_signal(sig, p))
798 else if (!group || thread_group_empty(p))
800 * There is just one thread and it does not need to be woken.
801 * It will dequeue unblocked signals before it runs again.
806 * Otherwise try to find a suitable thread.
808 t = signal->curr_target;
809 while (!wants_signal(sig, t)) {
811 if (t == signal->curr_target)
813 * No thread needs to be woken.
814 * Any eligible threads will see
815 * the signal in the queue soon.
819 signal->curr_target = t;
823 * Found a killable thread. If the signal will be fatal,
824 * then start taking the whole group down immediately.
826 if (sig_fatal(p, sig) &&
827 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
828 !sigismember(&t->real_blocked, sig) &&
830 !tracehook_consider_fatal_signal(t, sig))) {
832 * This signal will be fatal to the whole group.
834 if (!sig_kernel_coredump(sig)) {
836 * Start a group exit and wake everybody up.
837 * This way we don't have other threads
838 * running and doing things after a slower
839 * thread has the fatal signal pending.
841 signal->flags = SIGNAL_GROUP_EXIT;
842 signal->group_exit_code = sig;
843 signal->group_stop_count = 0;
846 sigaddset(&t->pending.signal, SIGKILL);
847 signal_wake_up(t, 1);
848 } while_each_thread(p, t);
854 * The signal is already in the shared-pending queue.
855 * Tell the chosen thread to wake up and dequeue it.
857 signal_wake_up(t, sig == SIGKILL);
861 static inline int legacy_queue(struct sigpending *signals, int sig)
863 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
866 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
867 int group, int from_ancestor_ns)
869 struct sigpending *pending;
873 trace_signal_generate(sig, info, t);
875 assert_spin_locked(&t->sighand->siglock);
877 if (!prepare_signal(sig, t, from_ancestor_ns))
880 pending = group ? &t->signal->shared_pending : &t->pending;
882 * Short-circuit ignored signals and support queuing
883 * exactly one non-rt signal, so that we can get more
884 * detailed information about the cause of the signal.
886 if (legacy_queue(pending, sig))
889 * fast-pathed signals for kernel-internal things like SIGSTOP
892 if (info == SEND_SIG_FORCED)
895 /* Real-time signals must be queued if sent by sigqueue, or
896 some other real-time mechanism. It is implementation
897 defined whether kill() does so. We attempt to do so, on
898 the principle of least surprise, but since kill is not
899 allowed to fail with EAGAIN when low on memory we just
900 make sure at least one signal gets delivered and don't
901 pass on the info struct. */
904 override_rlimit = (is_si_special(info) || info->si_code >= 0);
908 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
911 list_add_tail(&q->list, &pending->list);
912 switch ((unsigned long) info) {
913 case (unsigned long) SEND_SIG_NOINFO:
914 q->info.si_signo = sig;
915 q->info.si_errno = 0;
916 q->info.si_code = SI_USER;
917 q->info.si_pid = task_tgid_nr_ns(current,
918 task_active_pid_ns(t));
919 q->info.si_uid = current_uid();
921 case (unsigned long) SEND_SIG_PRIV:
922 q->info.si_signo = sig;
923 q->info.si_errno = 0;
924 q->info.si_code = SI_KERNEL;
929 copy_siginfo(&q->info, info);
930 if (from_ancestor_ns)
934 } else if (!is_si_special(info)) {
935 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
937 * Queue overflow, abort. We may abort if the
938 * signal was rt and sent by user using something
941 trace_signal_overflow_fail(sig, group, info);
945 * This is a silent loss of information. We still
946 * send the signal, but the *info bits are lost.
948 trace_signal_lose_info(sig, group, info);
953 signalfd_notify(t, sig);
954 sigaddset(&pending->signal, sig);
955 complete_signal(sig, t, group);
959 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
962 int from_ancestor_ns = 0;
965 from_ancestor_ns = si_fromuser(info) &&
966 !task_pid_nr_ns(current, task_active_pid_ns(t));
969 return __send_signal(sig, info, t, group, from_ancestor_ns);
972 static void print_fatal_signal(struct pt_regs *regs, int signr)
974 printk("%s/%d: potentially unexpected fatal signal %d.\n",
975 current->comm, task_pid_nr(current), signr);
977 #if defined(__i386__) && !defined(__arch_um__)
978 printk("code at %08lx: ", regs->ip);
981 for (i = 0; i < 16; i++) {
984 if (get_user(insn, (unsigned char *)(regs->ip + i)))
986 printk("%02x ", insn);
996 static int __init setup_print_fatal_signals(char *str)
998 get_option (&str, &print_fatal_signals);
1003 __setup("print-fatal-signals=", setup_print_fatal_signals);
1006 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1008 return send_signal(sig, info, p, 1);
1012 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1014 return send_signal(sig, info, t, 0);
1017 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1020 unsigned long flags;
1023 if (lock_task_sighand(p, &flags)) {
1024 ret = send_signal(sig, info, p, group);
1025 unlock_task_sighand(p, &flags);
1032 * Force a signal that the process can't ignore: if necessary
1033 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1035 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1036 * since we do not want to have a signal handler that was blocked
1037 * be invoked when user space had explicitly blocked it.
1039 * We don't want to have recursive SIGSEGV's etc, for example,
1040 * that is why we also clear SIGNAL_UNKILLABLE.
1043 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1045 unsigned long int flags;
1046 int ret, blocked, ignored;
1047 struct k_sigaction *action;
1049 spin_lock_irqsave(&t->sighand->siglock, flags);
1050 action = &t->sighand->action[sig-1];
1051 ignored = action->sa.sa_handler == SIG_IGN;
1052 blocked = sigismember(&t->blocked, sig);
1053 if (blocked || ignored) {
1054 action->sa.sa_handler = SIG_DFL;
1056 sigdelset(&t->blocked, sig);
1057 recalc_sigpending_and_wake(t);
1060 if (action->sa.sa_handler == SIG_DFL)
1061 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1062 ret = specific_send_sig_info(sig, info, t);
1063 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1069 * Nuke all other threads in the group.
1071 void zap_other_threads(struct task_struct *p)
1073 struct task_struct *t;
1075 p->signal->group_stop_count = 0;
1077 for (t = next_thread(p); t != p; t = next_thread(t)) {
1079 * Don't bother with already dead threads
1084 /* SIGKILL will be handled before any pending SIGSTOP */
1085 sigaddset(&t->pending.signal, SIGKILL);
1086 signal_wake_up(t, 1);
1090 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
1092 struct sighand_struct *sighand;
1096 sighand = rcu_dereference(tsk->sighand);
1097 if (unlikely(sighand == NULL))
1100 spin_lock_irqsave(&sighand->siglock, *flags);
1101 if (likely(sighand == tsk->sighand))
1103 spin_unlock_irqrestore(&sighand->siglock, *flags);
1111 * send signal info to all the members of a group
1112 * - the caller must hold the RCU read lock at least
1114 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1116 int ret = check_kill_permission(sig, info, p);
1119 ret = do_send_sig_info(sig, info, p, true);
1125 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1126 * control characters do (^C, ^Z etc)
1127 * - the caller must hold at least a readlock on tasklist_lock
1129 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1131 struct task_struct *p = NULL;
1132 int retval, success;
1136 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1137 int err = group_send_sig_info(sig, info, p);
1140 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1141 return success ? 0 : retval;
1144 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1147 struct task_struct *p;
1151 p = pid_task(pid, PIDTYPE_PID);
1153 error = group_send_sig_info(sig, info, p);
1154 if (unlikely(error == -ESRCH))
1156 * The task was unhashed in between, try again.
1157 * If it is dead, pid_task() will return NULL,
1158 * if we race with de_thread() it will find the
1169 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1173 error = kill_pid_info(sig, info, find_vpid(pid));
1178 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1179 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1180 uid_t uid, uid_t euid, u32 secid)
1183 struct task_struct *p;
1184 const struct cred *pcred;
1185 unsigned long flags;
1187 if (!valid_signal(sig))
1191 p = pid_task(pid, PIDTYPE_PID);
1196 pcred = __task_cred(p);
1197 if (si_fromuser(info) &&
1198 euid != pcred->suid && euid != pcred->uid &&
1199 uid != pcred->suid && uid != pcred->uid) {
1203 ret = security_task_kill(p, info, sig, secid);
1208 if (lock_task_sighand(p, &flags)) {
1209 ret = __send_signal(sig, info, p, 1, 0);
1210 unlock_task_sighand(p, &flags);
1218 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1221 * kill_something_info() interprets pid in interesting ways just like kill(2).
1223 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1224 * is probably wrong. Should make it like BSD or SYSV.
1227 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1233 ret = kill_pid_info(sig, info, find_vpid(pid));
1238 read_lock(&tasklist_lock);
1240 ret = __kill_pgrp_info(sig, info,
1241 pid ? find_vpid(-pid) : task_pgrp(current));
1243 int retval = 0, count = 0;
1244 struct task_struct * p;
1246 for_each_process(p) {
1247 if (task_pid_vnr(p) > 1 &&
1248 !same_thread_group(p, current)) {
1249 int err = group_send_sig_info(sig, info, p);
1255 ret = count ? retval : -ESRCH;
1257 read_unlock(&tasklist_lock);
1263 * These are for backward compatibility with the rest of the kernel source.
1267 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1270 * Make sure legacy kernel users don't send in bad values
1271 * (normal paths check this in check_kill_permission).
1273 if (!valid_signal(sig))
1276 return do_send_sig_info(sig, info, p, false);
1279 #define __si_special(priv) \
1280 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1283 send_sig(int sig, struct task_struct *p, int priv)
1285 return send_sig_info(sig, __si_special(priv), p);
1289 force_sig(int sig, struct task_struct *p)
1291 force_sig_info(sig, SEND_SIG_PRIV, p);
1295 * When things go south during signal handling, we
1296 * will force a SIGSEGV. And if the signal that caused
1297 * the problem was already a SIGSEGV, we'll want to
1298 * make sure we don't even try to deliver the signal..
1301 force_sigsegv(int sig, struct task_struct *p)
1303 if (sig == SIGSEGV) {
1304 unsigned long flags;
1305 spin_lock_irqsave(&p->sighand->siglock, flags);
1306 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1307 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1309 force_sig(SIGSEGV, p);
1313 int kill_pgrp(struct pid *pid, int sig, int priv)
1317 read_lock(&tasklist_lock);
1318 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1319 read_unlock(&tasklist_lock);
1323 EXPORT_SYMBOL(kill_pgrp);
1325 int kill_pid(struct pid *pid, int sig, int priv)
1327 return kill_pid_info(sig, __si_special(priv), pid);
1329 EXPORT_SYMBOL(kill_pid);
1332 * These functions support sending signals using preallocated sigqueue
1333 * structures. This is needed "because realtime applications cannot
1334 * afford to lose notifications of asynchronous events, like timer
1335 * expirations or I/O completions". In the case of Posix Timers
1336 * we allocate the sigqueue structure from the timer_create. If this
1337 * allocation fails we are able to report the failure to the application
1338 * with an EAGAIN error.
1340 struct sigqueue *sigqueue_alloc(void)
1342 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1345 q->flags |= SIGQUEUE_PREALLOC;
1350 void sigqueue_free(struct sigqueue *q)
1352 unsigned long flags;
1353 spinlock_t *lock = ¤t->sighand->siglock;
1355 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1357 * We must hold ->siglock while testing q->list
1358 * to serialize with collect_signal() or with
1359 * __exit_signal()->flush_sigqueue().
1361 spin_lock_irqsave(lock, flags);
1362 q->flags &= ~SIGQUEUE_PREALLOC;
1364 * If it is queued it will be freed when dequeued,
1365 * like the "regular" sigqueue.
1367 if (!list_empty(&q->list))
1369 spin_unlock_irqrestore(lock, flags);
1375 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1377 int sig = q->info.si_signo;
1378 struct sigpending *pending;
1379 unsigned long flags;
1382 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1385 if (!likely(lock_task_sighand(t, &flags)))
1388 ret = 1; /* the signal is ignored */
1389 if (!prepare_signal(sig, t, 0))
1393 if (unlikely(!list_empty(&q->list))) {
1395 * If an SI_TIMER entry is already queue just increment
1396 * the overrun count.
1398 BUG_ON(q->info.si_code != SI_TIMER);
1399 q->info.si_overrun++;
1402 q->info.si_overrun = 0;
1404 signalfd_notify(t, sig);
1405 pending = group ? &t->signal->shared_pending : &t->pending;
1406 list_add_tail(&q->list, &pending->list);
1407 sigaddset(&pending->signal, sig);
1408 complete_signal(sig, t, group);
1410 unlock_task_sighand(t, &flags);
1416 * Let a parent know about the death of a child.
1417 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1419 * Returns -1 if our parent ignored us and so we've switched to
1420 * self-reaping, or else @sig.
1422 int do_notify_parent(struct task_struct *tsk, int sig)
1424 struct siginfo info;
1425 unsigned long flags;
1426 struct sighand_struct *psig;
1431 /* do_notify_parent_cldstop should have been called instead. */
1432 BUG_ON(task_is_stopped_or_traced(tsk));
1434 BUG_ON(!task_ptrace(tsk) &&
1435 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1437 info.si_signo = sig;
1440 * we are under tasklist_lock here so our parent is tied to
1441 * us and cannot exit and release its namespace.
1443 * the only it can is to switch its nsproxy with sys_unshare,
1444 * bu uncharing pid namespaces is not allowed, so we'll always
1445 * see relevant namespace
1447 * write_lock() currently calls preempt_disable() which is the
1448 * same as rcu_read_lock(), but according to Oleg, this is not
1449 * correct to rely on this
1452 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1453 info.si_uid = __task_cred(tsk)->uid;
1456 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1457 tsk->signal->utime));
1458 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1459 tsk->signal->stime));
1461 info.si_status = tsk->exit_code & 0x7f;
1462 if (tsk->exit_code & 0x80)
1463 info.si_code = CLD_DUMPED;
1464 else if (tsk->exit_code & 0x7f)
1465 info.si_code = CLD_KILLED;
1467 info.si_code = CLD_EXITED;
1468 info.si_status = tsk->exit_code >> 8;
1471 psig = tsk->parent->sighand;
1472 spin_lock_irqsave(&psig->siglock, flags);
1473 if (!task_ptrace(tsk) && sig == SIGCHLD &&
1474 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1475 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1477 * We are exiting and our parent doesn't care. POSIX.1
1478 * defines special semantics for setting SIGCHLD to SIG_IGN
1479 * or setting the SA_NOCLDWAIT flag: we should be reaped
1480 * automatically and not left for our parent's wait4 call.
1481 * Rather than having the parent do it as a magic kind of
1482 * signal handler, we just set this to tell do_exit that we
1483 * can be cleaned up without becoming a zombie. Note that
1484 * we still call __wake_up_parent in this case, because a
1485 * blocked sys_wait4 might now return -ECHILD.
1487 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1488 * is implementation-defined: we do (if you don't want
1489 * it, just use SIG_IGN instead).
1491 ret = tsk->exit_signal = -1;
1492 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1495 if (valid_signal(sig) && sig > 0)
1496 __group_send_sig_info(sig, &info, tsk->parent);
1497 __wake_up_parent(tsk, tsk->parent);
1498 spin_unlock_irqrestore(&psig->siglock, flags);
1503 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1505 struct siginfo info;
1506 unsigned long flags;
1507 struct task_struct *parent;
1508 struct sighand_struct *sighand;
1510 if (task_ptrace(tsk))
1511 parent = tsk->parent;
1513 tsk = tsk->group_leader;
1514 parent = tsk->real_parent;
1517 info.si_signo = SIGCHLD;
1520 * see comment in do_notify_parent() abot the following 3 lines
1523 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1524 info.si_uid = __task_cred(tsk)->uid;
1527 info.si_utime = cputime_to_clock_t(tsk->utime);
1528 info.si_stime = cputime_to_clock_t(tsk->stime);
1533 info.si_status = SIGCONT;
1536 info.si_status = tsk->signal->group_exit_code & 0x7f;
1539 info.si_status = tsk->exit_code & 0x7f;
1545 sighand = parent->sighand;
1546 spin_lock_irqsave(&sighand->siglock, flags);
1547 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1548 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1549 __group_send_sig_info(SIGCHLD, &info, parent);
1551 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1553 __wake_up_parent(tsk, parent);
1554 spin_unlock_irqrestore(&sighand->siglock, flags);
1557 static inline int may_ptrace_stop(void)
1559 if (!likely(task_ptrace(current)))
1562 * Are we in the middle of do_coredump?
1563 * If so and our tracer is also part of the coredump stopping
1564 * is a deadlock situation, and pointless because our tracer
1565 * is dead so don't allow us to stop.
1566 * If SIGKILL was already sent before the caller unlocked
1567 * ->siglock we must see ->core_state != NULL. Otherwise it
1568 * is safe to enter schedule().
1570 if (unlikely(current->mm->core_state) &&
1571 unlikely(current->mm == current->parent->mm))
1578 * Return nonzero if there is a SIGKILL that should be waking us up.
1579 * Called with the siglock held.
1581 static int sigkill_pending(struct task_struct *tsk)
1583 return sigismember(&tsk->pending.signal, SIGKILL) ||
1584 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1588 * This must be called with current->sighand->siglock held.
1590 * This should be the path for all ptrace stops.
1591 * We always set current->last_siginfo while stopped here.
1592 * That makes it a way to test a stopped process for
1593 * being ptrace-stopped vs being job-control-stopped.
1595 * If we actually decide not to stop at all because the tracer
1596 * is gone, we keep current->exit_code unless clear_code.
1598 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1600 if (arch_ptrace_stop_needed(exit_code, info)) {
1602 * The arch code has something special to do before a
1603 * ptrace stop. This is allowed to block, e.g. for faults
1604 * on user stack pages. We can't keep the siglock while
1605 * calling arch_ptrace_stop, so we must release it now.
1606 * To preserve proper semantics, we must do this before
1607 * any signal bookkeeping like checking group_stop_count.
1608 * Meanwhile, a SIGKILL could come in before we retake the
1609 * siglock. That must prevent us from sleeping in TASK_TRACED.
1610 * So after regaining the lock, we must check for SIGKILL.
1612 spin_unlock_irq(¤t->sighand->siglock);
1613 arch_ptrace_stop(exit_code, info);
1614 spin_lock_irq(¤t->sighand->siglock);
1615 if (sigkill_pending(current))
1620 * If there is a group stop in progress,
1621 * we must participate in the bookkeeping.
1623 if (current->signal->group_stop_count > 0)
1624 --current->signal->group_stop_count;
1626 current->last_siginfo = info;
1627 current->exit_code = exit_code;
1629 /* Let the debugger run. */
1630 __set_current_state(TASK_TRACED);
1631 spin_unlock_irq(¤t->sighand->siglock);
1632 read_lock(&tasklist_lock);
1633 if (may_ptrace_stop()) {
1634 do_notify_parent_cldstop(current, CLD_TRAPPED);
1636 * Don't want to allow preemption here, because
1637 * sys_ptrace() needs this task to be inactive.
1639 * XXX: implement read_unlock_no_resched().
1642 read_unlock(&tasklist_lock);
1643 preempt_enable_no_resched();
1647 * By the time we got the lock, our tracer went away.
1648 * Don't drop the lock yet, another tracer may come.
1650 __set_current_state(TASK_RUNNING);
1652 current->exit_code = 0;
1653 read_unlock(&tasklist_lock);
1657 * While in TASK_TRACED, we were considered "frozen enough".
1658 * Now that we woke up, it's crucial if we're supposed to be
1659 * frozen that we freeze now before running anything substantial.
1664 * We are back. Now reacquire the siglock before touching
1665 * last_siginfo, so that we are sure to have synchronized with
1666 * any signal-sending on another CPU that wants to examine it.
1668 spin_lock_irq(¤t->sighand->siglock);
1669 current->last_siginfo = NULL;
1672 * Queued signals ignored us while we were stopped for tracing.
1673 * So check for any that we should take before resuming user mode.
1674 * This sets TIF_SIGPENDING, but never clears it.
1676 recalc_sigpending_tsk(current);
1679 void ptrace_notify(int exit_code)
1683 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1685 memset(&info, 0, sizeof info);
1686 info.si_signo = SIGTRAP;
1687 info.si_code = exit_code;
1688 info.si_pid = task_pid_vnr(current);
1689 info.si_uid = current_uid();
1691 /* Let the debugger run. */
1692 spin_lock_irq(¤t->sighand->siglock);
1693 ptrace_stop(exit_code, 1, &info);
1694 spin_unlock_irq(¤t->sighand->siglock);
1698 * This performs the stopping for SIGSTOP and other stop signals.
1699 * We have to stop all threads in the thread group.
1700 * Returns nonzero if we've actually stopped and released the siglock.
1701 * Returns zero if we didn't stop and still hold the siglock.
1703 static int do_signal_stop(int signr)
1705 struct signal_struct *sig = current->signal;
1708 if (!sig->group_stop_count) {
1709 struct task_struct *t;
1711 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1712 unlikely(signal_group_exit(sig)))
1715 * There is no group stop already in progress.
1716 * We must initiate one now.
1718 sig->group_exit_code = signr;
1720 sig->group_stop_count = 1;
1721 for (t = next_thread(current); t != current; t = next_thread(t))
1723 * Setting state to TASK_STOPPED for a group
1724 * stop is always done with the siglock held,
1725 * so this check has no races.
1727 if (!(t->flags & PF_EXITING) &&
1728 !task_is_stopped_or_traced(t)) {
1729 sig->group_stop_count++;
1730 signal_wake_up(t, 0);
1734 * If there are no other threads in the group, or if there is
1735 * a group stop in progress and we are the last to stop, report
1736 * to the parent. When ptraced, every thread reports itself.
1738 notify = sig->group_stop_count == 1 ? CLD_STOPPED : 0;
1739 notify = tracehook_notify_jctl(notify, CLD_STOPPED);
1741 * tracehook_notify_jctl() can drop and reacquire siglock, so
1742 * we keep ->group_stop_count != 0 before the call. If SIGCONT
1743 * or SIGKILL comes in between ->group_stop_count == 0.
1745 if (sig->group_stop_count) {
1746 if (!--sig->group_stop_count)
1747 sig->flags = SIGNAL_STOP_STOPPED;
1748 current->exit_code = sig->group_exit_code;
1749 __set_current_state(TASK_STOPPED);
1751 spin_unlock_irq(¤t->sighand->siglock);
1754 read_lock(&tasklist_lock);
1755 do_notify_parent_cldstop(current, notify);
1756 read_unlock(&tasklist_lock);
1759 /* Now we don't run again until woken by SIGCONT or SIGKILL */
1762 } while (try_to_freeze());
1764 tracehook_finish_jctl();
1765 current->exit_code = 0;
1770 static int ptrace_signal(int signr, siginfo_t *info,
1771 struct pt_regs *regs, void *cookie)
1773 if (!task_ptrace(current))
1776 ptrace_signal_deliver(regs, cookie);
1778 /* Let the debugger run. */
1779 ptrace_stop(signr, 0, info);
1781 /* We're back. Did the debugger cancel the sig? */
1782 signr = current->exit_code;
1786 current->exit_code = 0;
1788 /* Update the siginfo structure if the signal has
1789 changed. If the debugger wanted something
1790 specific in the siginfo structure then it should
1791 have updated *info via PTRACE_SETSIGINFO. */
1792 if (signr != info->si_signo) {
1793 info->si_signo = signr;
1795 info->si_code = SI_USER;
1796 info->si_pid = task_pid_vnr(current->parent);
1797 info->si_uid = task_uid(current->parent);
1800 /* If the (new) signal is now blocked, requeue it. */
1801 if (sigismember(¤t->blocked, signr)) {
1802 specific_send_sig_info(signr, info, current);
1809 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1810 struct pt_regs *regs, void *cookie)
1812 struct sighand_struct *sighand = current->sighand;
1813 struct signal_struct *signal = current->signal;
1818 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1819 * While in TASK_STOPPED, we were considered "frozen enough".
1820 * Now that we woke up, it's crucial if we're supposed to be
1821 * frozen that we freeze now before running anything substantial.
1825 spin_lock_irq(&sighand->siglock);
1827 * Every stopped thread goes here after wakeup. Check to see if
1828 * we should notify the parent, prepare_signal(SIGCONT) encodes
1829 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1831 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1832 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1833 ? CLD_CONTINUED : CLD_STOPPED;
1834 signal->flags &= ~SIGNAL_CLD_MASK;
1836 why = tracehook_notify_jctl(why, CLD_CONTINUED);
1837 spin_unlock_irq(&sighand->siglock);
1840 read_lock(&tasklist_lock);
1841 do_notify_parent_cldstop(current->group_leader, why);
1842 read_unlock(&tasklist_lock);
1848 struct k_sigaction *ka;
1850 * Tracing can induce an artifical signal and choose sigaction.
1851 * The return value in @signr determines the default action,
1852 * but @info->si_signo is the signal number we will report.
1854 signr = tracehook_get_signal(current, regs, info, return_ka);
1855 if (unlikely(signr < 0))
1857 if (unlikely(signr != 0))
1860 if (unlikely(signal->group_stop_count > 0) &&
1864 signr = dequeue_signal(current, ¤t->blocked,
1868 break; /* will return 0 */
1870 if (signr != SIGKILL) {
1871 signr = ptrace_signal(signr, info,
1877 ka = &sighand->action[signr-1];
1880 /* Trace actually delivered signals. */
1881 trace_signal_deliver(signr, info, ka);
1883 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1885 if (ka->sa.sa_handler != SIG_DFL) {
1886 /* Run the handler. */
1889 if (ka->sa.sa_flags & SA_ONESHOT)
1890 ka->sa.sa_handler = SIG_DFL;
1892 break; /* will return non-zero "signr" value */
1896 * Now we are doing the default action for this signal.
1898 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1902 * Global init gets no signals it doesn't want.
1903 * Container-init gets no signals it doesn't want from same
1906 * Note that if global/container-init sees a sig_kernel_only()
1907 * signal here, the signal must have been generated internally
1908 * or must have come from an ancestor namespace. In either
1909 * case, the signal cannot be dropped.
1911 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1912 !sig_kernel_only(signr))
1915 if (sig_kernel_stop(signr)) {
1917 * The default action is to stop all threads in
1918 * the thread group. The job control signals
1919 * do nothing in an orphaned pgrp, but SIGSTOP
1920 * always works. Note that siglock needs to be
1921 * dropped during the call to is_orphaned_pgrp()
1922 * because of lock ordering with tasklist_lock.
1923 * This allows an intervening SIGCONT to be posted.
1924 * We need to check for that and bail out if necessary.
1926 if (signr != SIGSTOP) {
1927 spin_unlock_irq(&sighand->siglock);
1929 /* signals can be posted during this window */
1931 if (is_current_pgrp_orphaned())
1934 spin_lock_irq(&sighand->siglock);
1937 if (likely(do_signal_stop(info->si_signo))) {
1938 /* It released the siglock. */
1943 * We didn't actually stop, due to a race
1944 * with SIGCONT or something like that.
1949 spin_unlock_irq(&sighand->siglock);
1952 * Anything else is fatal, maybe with a core dump.
1954 current->flags |= PF_SIGNALED;
1956 if (sig_kernel_coredump(signr)) {
1957 if (print_fatal_signals)
1958 print_fatal_signal(regs, info->si_signo);
1960 * If it was able to dump core, this kills all
1961 * other threads in the group and synchronizes with
1962 * their demise. If we lost the race with another
1963 * thread getting here, it set group_exit_code
1964 * first and our do_group_exit call below will use
1965 * that value and ignore the one we pass it.
1967 do_coredump(info->si_signo, info->si_signo, regs);
1971 * Death signals, no core dump.
1973 do_group_exit(info->si_signo);
1976 spin_unlock_irq(&sighand->siglock);
1980 void exit_signals(struct task_struct *tsk)
1983 struct task_struct *t;
1985 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1986 tsk->flags |= PF_EXITING;
1990 spin_lock_irq(&tsk->sighand->siglock);
1992 * From now this task is not visible for group-wide signals,
1993 * see wants_signal(), do_signal_stop().
1995 tsk->flags |= PF_EXITING;
1996 if (!signal_pending(tsk))
1999 /* It could be that __group_complete_signal() choose us to
2000 * notify about group-wide signal. Another thread should be
2001 * woken now to take the signal since we will not.
2003 for (t = tsk; (t = next_thread(t)) != tsk; )
2004 if (!signal_pending(t) && !(t->flags & PF_EXITING))
2005 recalc_sigpending_and_wake(t);
2007 if (unlikely(tsk->signal->group_stop_count) &&
2008 !--tsk->signal->group_stop_count) {
2009 tsk->signal->flags = SIGNAL_STOP_STOPPED;
2010 group_stop = tracehook_notify_jctl(CLD_STOPPED, CLD_STOPPED);
2013 spin_unlock_irq(&tsk->sighand->siglock);
2015 if (unlikely(group_stop)) {
2016 read_lock(&tasklist_lock);
2017 do_notify_parent_cldstop(tsk, group_stop);
2018 read_unlock(&tasklist_lock);
2022 EXPORT_SYMBOL(recalc_sigpending);
2023 EXPORT_SYMBOL_GPL(dequeue_signal);
2024 EXPORT_SYMBOL(flush_signals);
2025 EXPORT_SYMBOL(force_sig);
2026 EXPORT_SYMBOL(send_sig);
2027 EXPORT_SYMBOL(send_sig_info);
2028 EXPORT_SYMBOL(sigprocmask);
2029 EXPORT_SYMBOL(block_all_signals);
2030 EXPORT_SYMBOL(unblock_all_signals);
2034 * System call entry points.
2037 SYSCALL_DEFINE0(restart_syscall)
2039 struct restart_block *restart = ¤t_thread_info()->restart_block;
2040 return restart->fn(restart);
2043 long do_no_restart_syscall(struct restart_block *param)
2049 * We don't need to get the kernel lock - this is all local to this
2050 * particular thread.. (and that's good, because this is _heavily_
2051 * used by various programs)
2055 * This is also useful for kernel threads that want to temporarily
2056 * (or permanently) block certain signals.
2058 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2059 * interface happily blocks "unblockable" signals like SIGKILL
2062 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2066 spin_lock_irq(¤t->sighand->siglock);
2068 *oldset = current->blocked;
2073 sigorsets(¤t->blocked, ¤t->blocked, set);
2076 signandsets(¤t->blocked, ¤t->blocked, set);
2079 current->blocked = *set;
2084 recalc_sigpending();
2085 spin_unlock_irq(¤t->sighand->siglock);
2090 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, set,
2091 sigset_t __user *, oset, size_t, sigsetsize)
2093 int error = -EINVAL;
2094 sigset_t old_set, new_set;
2096 /* XXX: Don't preclude handling different sized sigset_t's. */
2097 if (sigsetsize != sizeof(sigset_t))
2102 if (copy_from_user(&new_set, set, sizeof(*set)))
2104 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2106 error = sigprocmask(how, &new_set, &old_set);
2112 spin_lock_irq(¤t->sighand->siglock);
2113 old_set = current->blocked;
2114 spin_unlock_irq(¤t->sighand->siglock);
2118 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2126 long do_sigpending(void __user *set, unsigned long sigsetsize)
2128 long error = -EINVAL;
2131 if (sigsetsize > sizeof(sigset_t))
2134 spin_lock_irq(¤t->sighand->siglock);
2135 sigorsets(&pending, ¤t->pending.signal,
2136 ¤t->signal->shared_pending.signal);
2137 spin_unlock_irq(¤t->sighand->siglock);
2139 /* Outside the lock because only this thread touches it. */
2140 sigandsets(&pending, ¤t->blocked, &pending);
2143 if (!copy_to_user(set, &pending, sigsetsize))
2150 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2152 return do_sigpending(set, sigsetsize);
2155 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2157 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2161 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2163 if (from->si_code < 0)
2164 return __copy_to_user(to, from, sizeof(siginfo_t))
2167 * If you change siginfo_t structure, please be sure
2168 * this code is fixed accordingly.
2169 * Please remember to update the signalfd_copyinfo() function
2170 * inside fs/signalfd.c too, in case siginfo_t changes.
2171 * It should never copy any pad contained in the structure
2172 * to avoid security leaks, but must copy the generic
2173 * 3 ints plus the relevant union member.
2175 err = __put_user(from->si_signo, &to->si_signo);
2176 err |= __put_user(from->si_errno, &to->si_errno);
2177 err |= __put_user((short)from->si_code, &to->si_code);
2178 switch (from->si_code & __SI_MASK) {
2180 err |= __put_user(from->si_pid, &to->si_pid);
2181 err |= __put_user(from->si_uid, &to->si_uid);
2184 err |= __put_user(from->si_tid, &to->si_tid);
2185 err |= __put_user(from->si_overrun, &to->si_overrun);
2186 err |= __put_user(from->si_ptr, &to->si_ptr);
2189 err |= __put_user(from->si_band, &to->si_band);
2190 err |= __put_user(from->si_fd, &to->si_fd);
2193 err |= __put_user(from->si_addr, &to->si_addr);
2194 #ifdef __ARCH_SI_TRAPNO
2195 err |= __put_user(from->si_trapno, &to->si_trapno);
2199 err |= __put_user(from->si_pid, &to->si_pid);
2200 err |= __put_user(from->si_uid, &to->si_uid);
2201 err |= __put_user(from->si_status, &to->si_status);
2202 err |= __put_user(from->si_utime, &to->si_utime);
2203 err |= __put_user(from->si_stime, &to->si_stime);
2205 case __SI_RT: /* This is not generated by the kernel as of now. */
2206 case __SI_MESGQ: /* But this is */
2207 err |= __put_user(from->si_pid, &to->si_pid);
2208 err |= __put_user(from->si_uid, &to->si_uid);
2209 err |= __put_user(from->si_ptr, &to->si_ptr);
2211 default: /* this is just in case for now ... */
2212 err |= __put_user(from->si_pid, &to->si_pid);
2213 err |= __put_user(from->si_uid, &to->si_uid);
2221 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2222 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2231 /* XXX: Don't preclude handling different sized sigset_t's. */
2232 if (sigsetsize != sizeof(sigset_t))
2235 if (copy_from_user(&these, uthese, sizeof(these)))
2239 * Invert the set of allowed signals to get those we
2242 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2246 if (copy_from_user(&ts, uts, sizeof(ts)))
2248 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2253 spin_lock_irq(¤t->sighand->siglock);
2254 sig = dequeue_signal(current, &these, &info);
2256 timeout = MAX_SCHEDULE_TIMEOUT;
2258 timeout = (timespec_to_jiffies(&ts)
2259 + (ts.tv_sec || ts.tv_nsec));
2262 /* None ready -- temporarily unblock those we're
2263 * interested while we are sleeping in so that we'll
2264 * be awakened when they arrive. */
2265 current->real_blocked = current->blocked;
2266 sigandsets(¤t->blocked, ¤t->blocked, &these);
2267 recalc_sigpending();
2268 spin_unlock_irq(¤t->sighand->siglock);
2270 timeout = schedule_timeout_interruptible(timeout);
2272 spin_lock_irq(¤t->sighand->siglock);
2273 sig = dequeue_signal(current, &these, &info);
2274 current->blocked = current->real_blocked;
2275 siginitset(¤t->real_blocked, 0);
2276 recalc_sigpending();
2279 spin_unlock_irq(¤t->sighand->siglock);
2284 if (copy_siginfo_to_user(uinfo, &info))
2296 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2298 struct siginfo info;
2300 info.si_signo = sig;
2302 info.si_code = SI_USER;
2303 info.si_pid = task_tgid_vnr(current);
2304 info.si_uid = current_uid();
2306 return kill_something_info(sig, &info, pid);
2310 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2312 struct task_struct *p;
2316 p = find_task_by_vpid(pid);
2317 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2318 error = check_kill_permission(sig, info, p);
2320 * The null signal is a permissions and process existence
2321 * probe. No signal is actually delivered.
2323 if (!error && sig) {
2324 error = do_send_sig_info(sig, info, p, false);
2326 * If lock_task_sighand() failed we pretend the task
2327 * dies after receiving the signal. The window is tiny,
2328 * and the signal is private anyway.
2330 if (unlikely(error == -ESRCH))
2339 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2341 struct siginfo info;
2343 info.si_signo = sig;
2345 info.si_code = SI_TKILL;
2346 info.si_pid = task_tgid_vnr(current);
2347 info.si_uid = current_uid();
2349 return do_send_specific(tgid, pid, sig, &info);
2353 * sys_tgkill - send signal to one specific thread
2354 * @tgid: the thread group ID of the thread
2355 * @pid: the PID of the thread
2356 * @sig: signal to be sent
2358 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2359 * exists but it's not belonging to the target process anymore. This
2360 * method solves the problem of threads exiting and PIDs getting reused.
2362 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2364 /* This is only valid for single tasks */
2365 if (pid <= 0 || tgid <= 0)
2368 return do_tkill(tgid, pid, sig);
2372 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2374 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2376 /* This is only valid for single tasks */
2380 return do_tkill(0, pid, sig);
2383 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2384 siginfo_t __user *, uinfo)
2388 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2391 /* Not even root can pretend to send signals from the kernel.
2392 Nor can they impersonate a kill(), which adds source info. */
2393 if (info.si_code >= 0)
2395 info.si_signo = sig;
2397 /* POSIX.1b doesn't mention process groups. */
2398 return kill_proc_info(sig, &info, pid);
2401 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2403 /* This is only valid for single tasks */
2404 if (pid <= 0 || tgid <= 0)
2407 /* Not even root can pretend to send signals from the kernel.
2408 Nor can they impersonate a kill(), which adds source info. */
2409 if (info->si_code >= 0)
2411 info->si_signo = sig;
2413 return do_send_specific(tgid, pid, sig, info);
2416 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2417 siginfo_t __user *, uinfo)
2421 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2424 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2427 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2429 struct task_struct *t = current;
2430 struct k_sigaction *k;
2433 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2436 k = &t->sighand->action[sig-1];
2438 spin_lock_irq(¤t->sighand->siglock);
2443 sigdelsetmask(&act->sa.sa_mask,
2444 sigmask(SIGKILL) | sigmask(SIGSTOP));
2448 * "Setting a signal action to SIG_IGN for a signal that is
2449 * pending shall cause the pending signal to be discarded,
2450 * whether or not it is blocked."
2452 * "Setting a signal action to SIG_DFL for a signal that is
2453 * pending and whose default action is to ignore the signal
2454 * (for example, SIGCHLD), shall cause the pending signal to
2455 * be discarded, whether or not it is blocked"
2457 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2459 sigaddset(&mask, sig);
2460 rm_from_queue_full(&mask, &t->signal->shared_pending);
2462 rm_from_queue_full(&mask, &t->pending);
2464 } while (t != current);
2468 spin_unlock_irq(¤t->sighand->siglock);
2473 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2478 oss.ss_sp = (void __user *) current->sas_ss_sp;
2479 oss.ss_size = current->sas_ss_size;
2480 oss.ss_flags = sas_ss_flags(sp);
2488 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
2490 error = __get_user(ss_sp, &uss->ss_sp) |
2491 __get_user(ss_flags, &uss->ss_flags) |
2492 __get_user(ss_size, &uss->ss_size);
2497 if (on_sig_stack(sp))
2503 * Note - this code used to test ss_flags incorrectly
2504 * old code may have been written using ss_flags==0
2505 * to mean ss_flags==SS_ONSTACK (as this was the only
2506 * way that worked) - this fix preserves that older
2509 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2512 if (ss_flags == SS_DISABLE) {
2517 if (ss_size < MINSIGSTKSZ)
2521 current->sas_ss_sp = (unsigned long) ss_sp;
2522 current->sas_ss_size = ss_size;
2528 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
2530 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
2531 __put_user(oss.ss_size, &uoss->ss_size) |
2532 __put_user(oss.ss_flags, &uoss->ss_flags);
2539 #ifdef __ARCH_WANT_SYS_SIGPENDING
2541 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
2543 return do_sigpending(set, sizeof(*set));
2548 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2549 /* Some platforms have their own version with special arguments others
2550 support only sys_rt_sigprocmask. */
2552 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, set,
2553 old_sigset_t __user *, oset)
2556 old_sigset_t old_set, new_set;
2560 if (copy_from_user(&new_set, set, sizeof(*set)))
2562 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2564 spin_lock_irq(¤t->sighand->siglock);
2565 old_set = current->blocked.sig[0];
2573 sigaddsetmask(¤t->blocked, new_set);
2576 sigdelsetmask(¤t->blocked, new_set);
2579 current->blocked.sig[0] = new_set;
2583 recalc_sigpending();
2584 spin_unlock_irq(¤t->sighand->siglock);
2590 old_set = current->blocked.sig[0];
2593 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2600 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2602 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2603 SYSCALL_DEFINE4(rt_sigaction, int, sig,
2604 const struct sigaction __user *, act,
2605 struct sigaction __user *, oact,
2608 struct k_sigaction new_sa, old_sa;
2611 /* XXX: Don't preclude handling different sized sigset_t's. */
2612 if (sigsetsize != sizeof(sigset_t))
2616 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2620 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2623 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2629 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2631 #ifdef __ARCH_WANT_SYS_SGETMASK
2634 * For backwards compatibility. Functionality superseded by sigprocmask.
2636 SYSCALL_DEFINE0(sgetmask)
2639 return current->blocked.sig[0];
2642 SYSCALL_DEFINE1(ssetmask, int, newmask)
2646 spin_lock_irq(¤t->sighand->siglock);
2647 old = current->blocked.sig[0];
2649 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2651 recalc_sigpending();
2652 spin_unlock_irq(¤t->sighand->siglock);
2656 #endif /* __ARCH_WANT_SGETMASK */
2658 #ifdef __ARCH_WANT_SYS_SIGNAL
2660 * For backwards compatibility. Functionality superseded by sigaction.
2662 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
2664 struct k_sigaction new_sa, old_sa;
2667 new_sa.sa.sa_handler = handler;
2668 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2669 sigemptyset(&new_sa.sa.sa_mask);
2671 ret = do_sigaction(sig, &new_sa, &old_sa);
2673 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2675 #endif /* __ARCH_WANT_SYS_SIGNAL */
2677 #ifdef __ARCH_WANT_SYS_PAUSE
2679 SYSCALL_DEFINE0(pause)
2681 current->state = TASK_INTERRUPTIBLE;
2683 return -ERESTARTNOHAND;
2688 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2689 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
2693 /* XXX: Don't preclude handling different sized sigset_t's. */
2694 if (sigsetsize != sizeof(sigset_t))
2697 if (copy_from_user(&newset, unewset, sizeof(newset)))
2699 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2701 spin_lock_irq(¤t->sighand->siglock);
2702 current->saved_sigmask = current->blocked;
2703 current->blocked = newset;
2704 recalc_sigpending();
2705 spin_unlock_irq(¤t->sighand->siglock);
2707 current->state = TASK_INTERRUPTIBLE;
2709 set_restore_sigmask();
2710 return -ERESTARTNOHAND;
2712 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2714 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2719 void __init signals_init(void)
2721 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);