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/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache *sigqueue_cachep;
43 static int sig_ignored(struct task_struct *t, int sig)
45 void __user * handler;
48 * Tracers always want to know about signals..
50 if (t->ptrace & PT_PTRACED)
54 * Blocked signals are never ignored, since the
55 * signal handler may change by the time it is
58 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
61 /* Is it explicitly or implicitly ignored? */
62 handler = t->sighand->action[sig-1].sa.sa_handler;
63 return handler == SIG_IGN ||
64 (handler == SIG_DFL && sig_kernel_ignore(sig));
68 * Re-calculate pending state from the set of locally pending
69 * signals, globally pending signals, and blocked signals.
71 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
76 switch (_NSIG_WORDS) {
78 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
79 ready |= signal->sig[i] &~ blocked->sig[i];
82 case 4: ready = signal->sig[3] &~ blocked->sig[3];
83 ready |= signal->sig[2] &~ blocked->sig[2];
84 ready |= signal->sig[1] &~ blocked->sig[1];
85 ready |= signal->sig[0] &~ blocked->sig[0];
88 case 2: ready = signal->sig[1] &~ blocked->sig[1];
89 ready |= signal->sig[0] &~ blocked->sig[0];
92 case 1: ready = signal->sig[0] &~ blocked->sig[0];
97 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
99 static int recalc_sigpending_tsk(struct task_struct *t)
101 if (t->signal->group_stop_count > 0 ||
102 PENDING(&t->pending, &t->blocked) ||
103 PENDING(&t->signal->shared_pending, &t->blocked)) {
104 set_tsk_thread_flag(t, TIF_SIGPENDING);
108 * We must never clear the flag in another thread, or in current
109 * when it's possible the current syscall is returning -ERESTART*.
110 * So we don't clear it here, and only callers who know they should do.
116 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
117 * This is superfluous when called on current, the wakeup is a harmless no-op.
119 void recalc_sigpending_and_wake(struct task_struct *t)
121 if (recalc_sigpending_tsk(t))
122 signal_wake_up(t, 0);
125 void recalc_sigpending(void)
127 if (!recalc_sigpending_tsk(current) && !freezing(current))
128 clear_thread_flag(TIF_SIGPENDING);
132 /* Given the mask, find the first available signal that should be serviced. */
134 int next_signal(struct sigpending *pending, sigset_t *mask)
136 unsigned long i, *s, *m, x;
139 s = pending->signal.sig;
141 switch (_NSIG_WORDS) {
143 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
144 if ((x = *s &~ *m) != 0) {
145 sig = ffz(~x) + i*_NSIG_BPW + 1;
150 case 2: if ((x = s[0] &~ m[0]) != 0)
152 else if ((x = s[1] &~ m[1]) != 0)
159 case 1: if ((x = *s &~ *m) != 0)
167 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
170 struct sigqueue *q = NULL;
171 struct user_struct *user;
174 * In order to avoid problems with "switch_user()", we want to make
175 * sure that the compiler doesn't re-load "t->user"
179 atomic_inc(&user->sigpending);
180 if (override_rlimit ||
181 atomic_read(&user->sigpending) <=
182 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
183 q = kmem_cache_alloc(sigqueue_cachep, flags);
184 if (unlikely(q == NULL)) {
185 atomic_dec(&user->sigpending);
187 INIT_LIST_HEAD(&q->list);
189 q->user = get_uid(user);
194 static void __sigqueue_free(struct sigqueue *q)
196 if (q->flags & SIGQUEUE_PREALLOC)
198 atomic_dec(&q->user->sigpending);
200 kmem_cache_free(sigqueue_cachep, q);
203 void flush_sigqueue(struct sigpending *queue)
207 sigemptyset(&queue->signal);
208 while (!list_empty(&queue->list)) {
209 q = list_entry(queue->list.next, struct sigqueue , list);
210 list_del_init(&q->list);
216 * Flush all pending signals for a task.
218 void flush_signals(struct task_struct *t)
222 spin_lock_irqsave(&t->sighand->siglock, flags);
223 clear_tsk_thread_flag(t, TIF_SIGPENDING);
224 flush_sigqueue(&t->pending);
225 flush_sigqueue(&t->signal->shared_pending);
226 spin_unlock_irqrestore(&t->sighand->siglock, flags);
229 void ignore_signals(struct task_struct *t)
233 for (i = 0; i < _NSIG; ++i)
234 t->sighand->action[i].sa.sa_handler = SIG_IGN;
240 * Flush all handlers for a task.
244 flush_signal_handlers(struct task_struct *t, int force_default)
247 struct k_sigaction *ka = &t->sighand->action[0];
248 for (i = _NSIG ; i != 0 ; i--) {
249 if (force_default || ka->sa.sa_handler != SIG_IGN)
250 ka->sa.sa_handler = SIG_DFL;
252 sigemptyset(&ka->sa.sa_mask);
257 int unhandled_signal(struct task_struct *tsk, int sig)
259 if (is_global_init(tsk))
261 if (tsk->ptrace & PT_PTRACED)
263 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
264 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
268 /* Notify the system that a driver wants to block all signals for this
269 * process, and wants to be notified if any signals at all were to be
270 * sent/acted upon. If the notifier routine returns non-zero, then the
271 * signal will be acted upon after all. If the notifier routine returns 0,
272 * then then signal will be blocked. Only one block per process is
273 * allowed. priv is a pointer to private data that the notifier routine
274 * can use to determine if the signal should be blocked or not. */
277 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
281 spin_lock_irqsave(¤t->sighand->siglock, flags);
282 current->notifier_mask = mask;
283 current->notifier_data = priv;
284 current->notifier = notifier;
285 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
288 /* Notify the system that blocking has ended. */
291 unblock_all_signals(void)
295 spin_lock_irqsave(¤t->sighand->siglock, flags);
296 current->notifier = NULL;
297 current->notifier_data = NULL;
299 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
302 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
304 struct sigqueue *q, *first = NULL;
305 int still_pending = 0;
307 if (unlikely(!sigismember(&list->signal, sig)))
311 * Collect the siginfo appropriate to this signal. Check if
312 * there is another siginfo for the same signal.
314 list_for_each_entry(q, &list->list, list) {
315 if (q->info.si_signo == sig) {
324 list_del_init(&first->list);
325 copy_siginfo(info, &first->info);
326 __sigqueue_free(first);
328 sigdelset(&list->signal, sig);
331 /* Ok, it wasn't in the queue. This must be
332 a fast-pathed signal or we must have been
333 out of queue space. So zero out the info.
335 sigdelset(&list->signal, sig);
336 info->si_signo = sig;
345 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
348 int sig = next_signal(pending, mask);
351 if (current->notifier) {
352 if (sigismember(current->notifier_mask, sig)) {
353 if (!(current->notifier)(current->notifier_data)) {
354 clear_thread_flag(TIF_SIGPENDING);
360 if (!collect_signal(sig, pending, info))
368 * Dequeue a signal and return the element to the caller, which is
369 * expected to free it.
371 * All callers have to hold the siglock.
373 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
377 /* We only dequeue private signals from ourselves, we don't let
378 * signalfd steal them
380 signr = __dequeue_signal(&tsk->pending, mask, info);
382 signr = __dequeue_signal(&tsk->signal->shared_pending,
387 * itimers are process shared and we restart periodic
388 * itimers in the signal delivery path to prevent DoS
389 * attacks in the high resolution timer case. This is
390 * compliant with the old way of self restarting
391 * itimers, as the SIGALRM is a legacy signal and only
392 * queued once. Changing the restart behaviour to
393 * restart the timer in the signal dequeue path is
394 * reducing the timer noise on heavy loaded !highres
397 if (unlikely(signr == SIGALRM)) {
398 struct hrtimer *tmr = &tsk->signal->real_timer;
400 if (!hrtimer_is_queued(tmr) &&
401 tsk->signal->it_real_incr.tv64 != 0) {
402 hrtimer_forward(tmr, tmr->base->get_time(),
403 tsk->signal->it_real_incr);
404 hrtimer_restart(tmr);
409 if (signr && unlikely(sig_kernel_stop(signr))) {
411 * Set a marker that we have dequeued a stop signal. Our
412 * caller might release the siglock and then the pending
413 * stop signal it is about to process is no longer in the
414 * pending bitmasks, but must still be cleared by a SIGCONT
415 * (and overruled by a SIGKILL). So those cases clear this
416 * shared flag after we've set it. Note that this flag may
417 * remain set after the signal we return is ignored or
418 * handled. That doesn't matter because its only purpose
419 * is to alert stop-signal processing code when another
420 * processor has come along and cleared the flag.
422 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
423 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
426 ((info->si_code & __SI_MASK) == __SI_TIMER) &&
427 info->si_sys_private) {
429 * Release the siglock to ensure proper locking order
430 * of timer locks outside of siglocks. Note, we leave
431 * irqs disabled here, since the posix-timers code is
432 * about to disable them again anyway.
434 spin_unlock(&tsk->sighand->siglock);
435 do_schedule_next_timer(info);
436 spin_lock(&tsk->sighand->siglock);
442 * Tell a process that it has a new active signal..
444 * NOTE! we rely on the previous spin_lock to
445 * lock interrupts for us! We can only be called with
446 * "siglock" held, and the local interrupt must
447 * have been disabled when that got acquired!
449 * No need to set need_resched since signal event passing
450 * goes through ->blocked
452 void signal_wake_up(struct task_struct *t, int resume)
456 set_tsk_thread_flag(t, TIF_SIGPENDING);
459 * For SIGKILL, we want to wake it up in the stopped/traced/killable
460 * case. We don't check t->state here because there is a race with it
461 * executing another processor and just now entering stopped state.
462 * By using wake_up_state, we ensure the process will wake up and
463 * handle its death signal.
465 mask = TASK_INTERRUPTIBLE;
467 mask |= TASK_WAKEKILL;
468 if (!wake_up_state(t, mask))
473 * Remove signals in mask from the pending set and queue.
474 * Returns 1 if any signals were found.
476 * All callers must be holding the siglock.
478 * This version takes a sigset mask and looks at all signals,
479 * not just those in the first mask word.
481 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
483 struct sigqueue *q, *n;
486 sigandsets(&m, mask, &s->signal);
487 if (sigisemptyset(&m))
490 signandsets(&s->signal, &s->signal, mask);
491 list_for_each_entry_safe(q, n, &s->list, list) {
492 if (sigismember(mask, q->info.si_signo)) {
493 list_del_init(&q->list);
500 * Remove signals in mask from the pending set and queue.
501 * Returns 1 if any signals were found.
503 * All callers must be holding the siglock.
505 static int rm_from_queue(unsigned long mask, struct sigpending *s)
507 struct sigqueue *q, *n;
509 if (!sigtestsetmask(&s->signal, mask))
512 sigdelsetmask(&s->signal, mask);
513 list_for_each_entry_safe(q, n, &s->list, list) {
514 if (q->info.si_signo < SIGRTMIN &&
515 (mask & sigmask(q->info.si_signo))) {
516 list_del_init(&q->list);
524 * Bad permissions for sending the signal
526 static int check_kill_permission(int sig, struct siginfo *info,
527 struct task_struct *t)
530 if (!valid_signal(sig))
533 if (info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info))) {
534 error = audit_signal_info(sig, t); /* Let audit system see the signal */
538 if (((sig != SIGCONT) ||
539 (task_session_nr(current) != task_session_nr(t)))
540 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
541 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
542 && !capable(CAP_KILL))
546 return security_task_kill(t, info, sig, 0);
550 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
553 * Handle magic process-wide effects of stop/continue signals.
554 * Unlike the signal actions, these happen immediately at signal-generation
555 * time regardless of blocking, ignoring, or handling. This does the
556 * actual continuing for SIGCONT, but not the actual stopping for stop
557 * signals. The process stop is done as a signal action for SIG_DFL.
559 static void handle_stop_signal(int sig, struct task_struct *p)
561 struct task_struct *t;
563 if (p->signal->flags & SIGNAL_GROUP_EXIT)
565 * The process is in the middle of dying already.
569 if (sig_kernel_stop(sig)) {
571 * This is a stop signal. Remove SIGCONT from all queues.
573 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
576 rm_from_queue(sigmask(SIGCONT), &t->pending);
579 } else if (sig == SIGCONT) {
581 * Remove all stop signals from all queues,
582 * and wake all threads.
584 if (unlikely(p->signal->group_stop_count > 0)) {
586 * There was a group stop in progress. We'll
587 * pretend it finished before we got here. We are
588 * obliged to report it to the parent: if the
589 * SIGSTOP happened "after" this SIGCONT, then it
590 * would have cleared this pending SIGCONT. If it
591 * happened "before" this SIGCONT, then the parent
592 * got the SIGCHLD about the stop finishing before
593 * the continue happened. We do the notification
594 * now, and it's as if the stop had finished and
595 * the SIGCHLD was pending on entry to this kill.
597 p->signal->group_stop_count = 0;
598 p->signal->flags = SIGNAL_STOP_CONTINUED;
599 spin_unlock(&p->sighand->siglock);
600 do_notify_parent_cldstop(p, CLD_STOPPED);
601 spin_lock(&p->sighand->siglock);
603 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
607 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
610 * If there is a handler for SIGCONT, we must make
611 * sure that no thread returns to user mode before
612 * we post the signal, in case it was the only
613 * thread eligible to run the signal handler--then
614 * it must not do anything between resuming and
615 * running the handler. With the TIF_SIGPENDING
616 * flag set, the thread will pause and acquire the
617 * siglock that we hold now and until we've queued
618 * the pending signal.
620 * Wake up the stopped thread _after_ setting
623 state = __TASK_STOPPED;
624 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
625 set_tsk_thread_flag(t, TIF_SIGPENDING);
626 state |= TASK_INTERRUPTIBLE;
628 wake_up_state(t, state);
633 if (p->signal->flags & SIGNAL_STOP_STOPPED) {
635 * We were in fact stopped, and are now continued.
636 * Notify the parent with CLD_CONTINUED.
638 p->signal->flags = SIGNAL_STOP_CONTINUED;
639 p->signal->group_exit_code = 0;
640 spin_unlock(&p->sighand->siglock);
641 do_notify_parent_cldstop(p, CLD_CONTINUED);
642 spin_lock(&p->sighand->siglock);
645 * We are not stopped, but there could be a stop
646 * signal in the middle of being processed after
647 * being removed from the queue. Clear that too.
649 p->signal->flags = 0;
651 } else if (sig == SIGKILL) {
653 * Make sure that any pending stop signal already dequeued
654 * is undone by the wakeup for SIGKILL.
656 p->signal->flags = 0;
660 static inline int legacy_queue(struct sigpending *signals, int sig)
662 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
665 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
666 struct sigpending *signals)
668 struct sigqueue * q = NULL;
671 * Deliver the signal to listening signalfds. This must be called
672 * with the sighand lock held.
674 signalfd_notify(t, sig);
677 * fast-pathed signals for kernel-internal things like SIGSTOP
680 if (info == SEND_SIG_FORCED)
683 /* Real-time signals must be queued if sent by sigqueue, or
684 some other real-time mechanism. It is implementation
685 defined whether kill() does so. We attempt to do so, on
686 the principle of least surprise, but since kill is not
687 allowed to fail with EAGAIN when low on memory we just
688 make sure at least one signal gets delivered and don't
689 pass on the info struct. */
691 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
692 (is_si_special(info) ||
693 info->si_code >= 0)));
695 list_add_tail(&q->list, &signals->list);
696 switch ((unsigned long) info) {
697 case (unsigned long) SEND_SIG_NOINFO:
698 q->info.si_signo = sig;
699 q->info.si_errno = 0;
700 q->info.si_code = SI_USER;
701 q->info.si_pid = task_pid_vnr(current);
702 q->info.si_uid = current->uid;
704 case (unsigned long) SEND_SIG_PRIV:
705 q->info.si_signo = sig;
706 q->info.si_errno = 0;
707 q->info.si_code = SI_KERNEL;
712 copy_siginfo(&q->info, info);
715 } else if (!is_si_special(info)) {
716 if (sig >= SIGRTMIN && info->si_code != SI_USER)
718 * Queue overflow, abort. We may abort if the signal was rt
719 * and sent by user using something other than kill().
725 sigaddset(&signals->signal, sig);
729 int print_fatal_signals;
731 static void print_fatal_signal(struct pt_regs *regs, int signr)
733 printk("%s/%d: potentially unexpected fatal signal %d.\n",
734 current->comm, task_pid_nr(current), signr);
736 #if defined(__i386__) && !defined(__arch_um__)
737 printk("code at %08lx: ", regs->ip);
740 for (i = 0; i < 16; i++) {
743 __get_user(insn, (unsigned char *)(regs->ip + i));
744 printk("%02x ", insn);
752 static int __init setup_print_fatal_signals(char *str)
754 get_option (&str, &print_fatal_signals);
759 __setup("print-fatal-signals=", setup_print_fatal_signals);
762 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
766 BUG_ON(!irqs_disabled());
767 assert_spin_locked(&t->sighand->siglock);
769 /* Short-circuit ignored signals. */
770 if (sig_ignored(t, sig))
773 /* Support queueing exactly one non-rt signal, so that we
774 can get more detailed information about the cause of
776 if (legacy_queue(&t->pending, sig))
779 ret = send_signal(sig, info, t, &t->pending);
780 if (!ret && !sigismember(&t->blocked, sig))
781 signal_wake_up(t, sig == SIGKILL);
787 * Force a signal that the process can't ignore: if necessary
788 * we unblock the signal and change any SIG_IGN to SIG_DFL.
790 * Note: If we unblock the signal, we always reset it to SIG_DFL,
791 * since we do not want to have a signal handler that was blocked
792 * be invoked when user space had explicitly blocked it.
794 * We don't want to have recursive SIGSEGV's etc, for example.
797 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
799 unsigned long int flags;
800 int ret, blocked, ignored;
801 struct k_sigaction *action;
803 spin_lock_irqsave(&t->sighand->siglock, flags);
804 action = &t->sighand->action[sig-1];
805 ignored = action->sa.sa_handler == SIG_IGN;
806 blocked = sigismember(&t->blocked, sig);
807 if (blocked || ignored) {
808 action->sa.sa_handler = SIG_DFL;
810 sigdelset(&t->blocked, sig);
811 recalc_sigpending_and_wake(t);
814 ret = specific_send_sig_info(sig, info, t);
815 spin_unlock_irqrestore(&t->sighand->siglock, flags);
821 force_sig_specific(int sig, struct task_struct *t)
823 force_sig_info(sig, SEND_SIG_FORCED, t);
827 * Test if P wants to take SIG. After we've checked all threads with this,
828 * it's equivalent to finding no threads not blocking SIG. Any threads not
829 * blocking SIG were ruled out because they are not running and already
830 * have pending signals. Such threads will dequeue from the shared queue
831 * as soon as they're available, so putting the signal on the shared queue
832 * will be equivalent to sending it to one such thread.
834 static inline int wants_signal(int sig, struct task_struct *p)
836 if (sigismember(&p->blocked, sig))
838 if (p->flags & PF_EXITING)
842 if (task_is_stopped_or_traced(p))
844 return task_curr(p) || !signal_pending(p);
848 __group_complete_signal(int sig, struct task_struct *p)
850 struct task_struct *t;
853 * Now find a thread we can wake up to take the signal off the queue.
855 * If the main thread wants the signal, it gets first crack.
856 * Probably the least surprising to the average bear.
858 if (wants_signal(sig, p))
860 else if (thread_group_empty(p))
862 * There is just one thread and it does not need to be woken.
863 * It will dequeue unblocked signals before it runs again.
868 * Otherwise try to find a suitable thread.
870 t = p->signal->curr_target;
872 /* restart balancing at this thread */
873 t = p->signal->curr_target = p;
875 while (!wants_signal(sig, t)) {
877 if (t == p->signal->curr_target)
879 * No thread needs to be woken.
880 * Any eligible threads will see
881 * the signal in the queue soon.
885 p->signal->curr_target = t;
889 * Found a killable thread. If the signal will be fatal,
890 * then start taking the whole group down immediately.
892 if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
893 !sigismember(&t->real_blocked, sig) &&
894 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
896 * This signal will be fatal to the whole group.
898 if (!sig_kernel_coredump(sig)) {
900 * Start a group exit and wake everybody up.
901 * This way we don't have other threads
902 * running and doing things after a slower
903 * thread has the fatal signal pending.
905 p->signal->flags = SIGNAL_GROUP_EXIT;
906 p->signal->group_exit_code = sig;
907 p->signal->group_stop_count = 0;
910 sigaddset(&t->pending.signal, SIGKILL);
911 signal_wake_up(t, 1);
912 } while_each_thread(p, t);
918 * The signal is already in the shared-pending queue.
919 * Tell the chosen thread to wake up and dequeue it.
921 signal_wake_up(t, sig == SIGKILL);
926 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
930 assert_spin_locked(&p->sighand->siglock);
931 handle_stop_signal(sig, p);
933 /* Short-circuit ignored signals. */
934 if (sig_ignored(p, sig))
937 if (legacy_queue(&p->signal->shared_pending, sig))
938 /* This is a non-RT signal and we already have one queued. */
942 * Put this signal on the shared-pending queue, or fail with EAGAIN.
943 * We always use the shared queue for process-wide signals,
944 * to avoid several races.
946 ret = send_signal(sig, info, p, &p->signal->shared_pending);
950 __group_complete_signal(sig, p);
955 * Nuke all other threads in the group.
957 void zap_other_threads(struct task_struct *p)
959 struct task_struct *t;
961 p->signal->group_stop_count = 0;
963 for (t = next_thread(p); t != p; t = next_thread(t)) {
965 * Don't bother with already dead threads
970 /* SIGKILL will be handled before any pending SIGSTOP */
971 sigaddset(&t->pending.signal, SIGKILL);
972 signal_wake_up(t, 1);
976 int __fatal_signal_pending(struct task_struct *tsk)
978 return sigismember(&tsk->pending.signal, SIGKILL);
980 EXPORT_SYMBOL(__fatal_signal_pending);
983 * Must be called under rcu_read_lock() or with tasklist_lock read-held.
985 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
987 struct sighand_struct *sighand;
990 sighand = rcu_dereference(tsk->sighand);
991 if (unlikely(sighand == NULL))
994 spin_lock_irqsave(&sighand->siglock, *flags);
995 if (likely(sighand == tsk->sighand))
997 spin_unlock_irqrestore(&sighand->siglock, *flags);
1003 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1005 unsigned long flags;
1008 ret = check_kill_permission(sig, info, p);
1012 if (lock_task_sighand(p, &flags)) {
1013 ret = __group_send_sig_info(sig, info, p);
1014 unlock_task_sighand(p, &flags);
1022 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1023 * control characters do (^C, ^Z etc)
1026 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1028 struct task_struct *p = NULL;
1029 int retval, success;
1033 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1034 int err = group_send_sig_info(sig, info, p);
1037 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1038 return success ? 0 : retval;
1041 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1044 struct task_struct *p;
1047 if (unlikely(sig_needs_tasklist(sig)))
1048 read_lock(&tasklist_lock);
1051 p = pid_task(pid, PIDTYPE_PID);
1053 error = group_send_sig_info(sig, info, p);
1054 if (unlikely(error == -ESRCH))
1056 * The task was unhashed in between, try again.
1057 * If it is dead, pid_task() will return NULL,
1058 * if we race with de_thread() it will find the
1064 if (unlikely(sig_needs_tasklist(sig)))
1065 read_unlock(&tasklist_lock);
1071 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1075 error = kill_pid_info(sig, info, find_vpid(pid));
1080 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1081 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1082 uid_t uid, uid_t euid, u32 secid)
1085 struct task_struct *p;
1087 if (!valid_signal(sig))
1090 read_lock(&tasklist_lock);
1091 p = pid_task(pid, PIDTYPE_PID);
1096 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1097 && (euid != p->suid) && (euid != p->uid)
1098 && (uid != p->suid) && (uid != p->uid)) {
1102 ret = security_task_kill(p, info, sig, secid);
1105 if (sig && p->sighand) {
1106 unsigned long flags;
1107 spin_lock_irqsave(&p->sighand->siglock, flags);
1108 ret = __group_send_sig_info(sig, info, p);
1109 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1112 read_unlock(&tasklist_lock);
1115 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1118 * kill_something_info() interprets pid in interesting ways just like kill(2).
1120 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1121 * is probably wrong. Should make it like BSD or SYSV.
1124 static int kill_something_info(int sig, struct siginfo *info, int pid)
1130 ret = kill_pid_info(sig, info, find_vpid(pid));
1135 read_lock(&tasklist_lock);
1137 ret = __kill_pgrp_info(sig, info,
1138 pid ? find_vpid(-pid) : task_pgrp(current));
1140 int retval = 0, count = 0;
1141 struct task_struct * p;
1143 for_each_process(p) {
1144 if (p->pid > 1 && !same_thread_group(p, current)) {
1145 int err = group_send_sig_info(sig, info, p);
1151 ret = count ? retval : -ESRCH;
1153 read_unlock(&tasklist_lock);
1159 * These are for backward compatibility with the rest of the kernel source.
1163 * These two are the most common entry points. They send a signal
1164 * just to the specific thread.
1167 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1170 unsigned long flags;
1173 * Make sure legacy kernel users don't send in bad values
1174 * (normal paths check this in check_kill_permission).
1176 if (!valid_signal(sig))
1180 * We need the tasklist lock even for the specific
1181 * thread case (when we don't need to follow the group
1182 * lists) in order to avoid races with "p->sighand"
1183 * going away or changing from under us.
1185 read_lock(&tasklist_lock);
1186 spin_lock_irqsave(&p->sighand->siglock, flags);
1187 ret = specific_send_sig_info(sig, info, p);
1188 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1189 read_unlock(&tasklist_lock);
1193 #define __si_special(priv) \
1194 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1197 send_sig(int sig, struct task_struct *p, int priv)
1199 return send_sig_info(sig, __si_special(priv), p);
1203 force_sig(int sig, struct task_struct *p)
1205 force_sig_info(sig, SEND_SIG_PRIV, p);
1209 * When things go south during signal handling, we
1210 * will force a SIGSEGV. And if the signal that caused
1211 * the problem was already a SIGSEGV, we'll want to
1212 * make sure we don't even try to deliver the signal..
1215 force_sigsegv(int sig, struct task_struct *p)
1217 if (sig == SIGSEGV) {
1218 unsigned long flags;
1219 spin_lock_irqsave(&p->sighand->siglock, flags);
1220 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1221 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1223 force_sig(SIGSEGV, p);
1227 int kill_pgrp(struct pid *pid, int sig, int priv)
1231 read_lock(&tasklist_lock);
1232 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1233 read_unlock(&tasklist_lock);
1237 EXPORT_SYMBOL(kill_pgrp);
1239 int kill_pid(struct pid *pid, int sig, int priv)
1241 return kill_pid_info(sig, __si_special(priv), pid);
1243 EXPORT_SYMBOL(kill_pid);
1246 kill_proc(pid_t pid, int sig, int priv)
1251 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1257 * These functions support sending signals using preallocated sigqueue
1258 * structures. This is needed "because realtime applications cannot
1259 * afford to lose notifications of asynchronous events, like timer
1260 * expirations or I/O completions". In the case of Posix Timers
1261 * we allocate the sigqueue structure from the timer_create. If this
1262 * allocation fails we are able to report the failure to the application
1263 * with an EAGAIN error.
1266 struct sigqueue *sigqueue_alloc(void)
1270 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1271 q->flags |= SIGQUEUE_PREALLOC;
1275 void sigqueue_free(struct sigqueue *q)
1277 unsigned long flags;
1278 spinlock_t *lock = ¤t->sighand->siglock;
1280 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1282 * If the signal is still pending remove it from the
1283 * pending queue. We must hold ->siglock while testing
1284 * q->list to serialize with collect_signal().
1286 spin_lock_irqsave(lock, flags);
1287 if (!list_empty(&q->list))
1288 list_del_init(&q->list);
1289 spin_unlock_irqrestore(lock, flags);
1291 q->flags &= ~SIGQUEUE_PREALLOC;
1295 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1297 unsigned long flags;
1300 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1303 * The rcu based delayed sighand destroy makes it possible to
1304 * run this without tasklist lock held. The task struct itself
1305 * cannot go away as create_timer did get_task_struct().
1307 * We return -1, when the task is marked exiting, so
1308 * posix_timer_event can redirect it to the group leader
1312 if (!likely(lock_task_sighand(p, &flags))) {
1317 if (unlikely(!list_empty(&q->list))) {
1319 * If an SI_TIMER entry is already queue just increment
1320 * the overrun count.
1322 BUG_ON(q->info.si_code != SI_TIMER);
1323 q->info.si_overrun++;
1326 /* Short-circuit ignored signals. */
1327 if (sig_ignored(p, sig)) {
1332 * Deliver the signal to listening signalfds. This must be called
1333 * with the sighand lock held.
1335 signalfd_notify(p, sig);
1337 list_add_tail(&q->list, &p->pending.list);
1338 sigaddset(&p->pending.signal, sig);
1339 if (!sigismember(&p->blocked, sig))
1340 signal_wake_up(p, sig == SIGKILL);
1343 unlock_task_sighand(p, &flags);
1351 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1353 unsigned long flags;
1356 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1358 read_lock(&tasklist_lock);
1359 /* Since it_lock is held, p->sighand cannot be NULL. */
1360 spin_lock_irqsave(&p->sighand->siglock, flags);
1361 handle_stop_signal(sig, p);
1363 /* Short-circuit ignored signals. */
1364 if (sig_ignored(p, sig)) {
1369 if (unlikely(!list_empty(&q->list))) {
1371 * If an SI_TIMER entry is already queue just increment
1372 * the overrun count. Other uses should not try to
1373 * send the signal multiple times.
1375 BUG_ON(q->info.si_code != SI_TIMER);
1376 q->info.si_overrun++;
1380 * Deliver the signal to listening signalfds. This must be called
1381 * with the sighand lock held.
1383 signalfd_notify(p, sig);
1386 * Put this signal on the shared-pending queue.
1387 * We always use the shared queue for process-wide signals,
1388 * to avoid several races.
1390 list_add_tail(&q->list, &p->signal->shared_pending.list);
1391 sigaddset(&p->signal->shared_pending.signal, sig);
1393 __group_complete_signal(sig, p);
1395 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1396 read_unlock(&tasklist_lock);
1401 * Wake up any threads in the parent blocked in wait* syscalls.
1403 static inline void __wake_up_parent(struct task_struct *p,
1404 struct task_struct *parent)
1406 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1410 * Let a parent know about the death of a child.
1411 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1414 void do_notify_parent(struct task_struct *tsk, int sig)
1416 struct siginfo info;
1417 unsigned long flags;
1418 struct sighand_struct *psig;
1422 /* do_notify_parent_cldstop should have been called instead. */
1423 BUG_ON(task_is_stopped_or_traced(tsk));
1425 BUG_ON(!tsk->ptrace &&
1426 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1428 info.si_signo = sig;
1431 * we are under tasklist_lock here so our parent is tied to
1432 * us and cannot exit and release its namespace.
1434 * the only it can is to switch its nsproxy with sys_unshare,
1435 * bu uncharing pid namespaces is not allowed, so we'll always
1436 * see relevant namespace
1438 * write_lock() currently calls preempt_disable() which is the
1439 * same as rcu_read_lock(), but according to Oleg, this is not
1440 * correct to rely on this
1443 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1446 info.si_uid = tsk->uid;
1448 /* FIXME: find out whether or not this is supposed to be c*time. */
1449 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1450 tsk->signal->utime));
1451 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1452 tsk->signal->stime));
1454 info.si_status = tsk->exit_code & 0x7f;
1455 if (tsk->exit_code & 0x80)
1456 info.si_code = CLD_DUMPED;
1457 else if (tsk->exit_code & 0x7f)
1458 info.si_code = CLD_KILLED;
1460 info.si_code = CLD_EXITED;
1461 info.si_status = tsk->exit_code >> 8;
1464 psig = tsk->parent->sighand;
1465 spin_lock_irqsave(&psig->siglock, flags);
1466 if (!tsk->ptrace && sig == SIGCHLD &&
1467 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1468 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1470 * We are exiting and our parent doesn't care. POSIX.1
1471 * defines special semantics for setting SIGCHLD to SIG_IGN
1472 * or setting the SA_NOCLDWAIT flag: we should be reaped
1473 * automatically and not left for our parent's wait4 call.
1474 * Rather than having the parent do it as a magic kind of
1475 * signal handler, we just set this to tell do_exit that we
1476 * can be cleaned up without becoming a zombie. Note that
1477 * we still call __wake_up_parent in this case, because a
1478 * blocked sys_wait4 might now return -ECHILD.
1480 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1481 * is implementation-defined: we do (if you don't want
1482 * it, just use SIG_IGN instead).
1484 tsk->exit_signal = -1;
1485 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1488 if (valid_signal(sig) && sig > 0)
1489 __group_send_sig_info(sig, &info, tsk->parent);
1490 __wake_up_parent(tsk, tsk->parent);
1491 spin_unlock_irqrestore(&psig->siglock, flags);
1494 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1496 struct siginfo info;
1497 unsigned long flags;
1498 struct task_struct *parent;
1499 struct sighand_struct *sighand;
1501 if (tsk->ptrace & PT_PTRACED)
1502 parent = tsk->parent;
1504 tsk = tsk->group_leader;
1505 parent = tsk->real_parent;
1508 info.si_signo = SIGCHLD;
1511 * see comment in do_notify_parent() abot the following 3 lines
1514 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1517 info.si_uid = tsk->uid;
1519 /* FIXME: find out whether or not this is supposed to be c*time. */
1520 info.si_utime = cputime_to_jiffies(tsk->utime);
1521 info.si_stime = cputime_to_jiffies(tsk->stime);
1526 info.si_status = SIGCONT;
1529 info.si_status = tsk->signal->group_exit_code & 0x7f;
1532 info.si_status = tsk->exit_code & 0x7f;
1538 sighand = parent->sighand;
1539 spin_lock_irqsave(&sighand->siglock, flags);
1540 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1541 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1542 __group_send_sig_info(SIGCHLD, &info, parent);
1544 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1546 __wake_up_parent(tsk, parent);
1547 spin_unlock_irqrestore(&sighand->siglock, flags);
1550 static inline int may_ptrace_stop(void)
1552 if (!likely(current->ptrace & PT_PTRACED))
1555 * Are we in the middle of do_coredump?
1556 * If so and our tracer is also part of the coredump stopping
1557 * is a deadlock situation, and pointless because our tracer
1558 * is dead so don't allow us to stop.
1559 * If SIGKILL was already sent before the caller unlocked
1560 * ->siglock we must see ->core_waiters != 0. Otherwise it
1561 * is safe to enter schedule().
1563 if (unlikely(current->mm->core_waiters) &&
1564 unlikely(current->mm == current->parent->mm))
1571 * Return nonzero if there is a SIGKILL that should be waking us up.
1572 * Called with the siglock held.
1574 static int sigkill_pending(struct task_struct *tsk)
1576 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1577 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1578 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1582 * This must be called with current->sighand->siglock held.
1584 * This should be the path for all ptrace stops.
1585 * We always set current->last_siginfo while stopped here.
1586 * That makes it a way to test a stopped process for
1587 * being ptrace-stopped vs being job-control-stopped.
1589 * If we actually decide not to stop at all because the tracer
1590 * is gone, we keep current->exit_code unless clear_code.
1592 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1596 if (arch_ptrace_stop_needed(exit_code, info)) {
1598 * The arch code has something special to do before a
1599 * ptrace stop. This is allowed to block, e.g. for faults
1600 * on user stack pages. We can't keep the siglock while
1601 * calling arch_ptrace_stop, so we must release it now.
1602 * To preserve proper semantics, we must do this before
1603 * any signal bookkeeping like checking group_stop_count.
1604 * Meanwhile, a SIGKILL could come in before we retake the
1605 * siglock. That must prevent us from sleeping in TASK_TRACED.
1606 * So after regaining the lock, we must check for SIGKILL.
1608 spin_unlock_irq(¤t->sighand->siglock);
1609 arch_ptrace_stop(exit_code, info);
1610 spin_lock_irq(¤t->sighand->siglock);
1611 killed = sigkill_pending(current);
1615 * If there is a group stop in progress,
1616 * we must participate in the bookkeeping.
1618 if (current->signal->group_stop_count > 0)
1619 --current->signal->group_stop_count;
1621 current->last_siginfo = info;
1622 current->exit_code = exit_code;
1624 /* Let the debugger run. */
1625 __set_current_state(TASK_TRACED);
1626 spin_unlock_irq(¤t->sighand->siglock);
1627 read_lock(&tasklist_lock);
1628 if (!unlikely(killed) && may_ptrace_stop()) {
1629 do_notify_parent_cldstop(current, CLD_TRAPPED);
1630 read_unlock(&tasklist_lock);
1634 * By the time we got the lock, our tracer went away.
1635 * Don't drop the lock yet, another tracer may come.
1637 __set_current_state(TASK_RUNNING);
1639 current->exit_code = 0;
1640 read_unlock(&tasklist_lock);
1644 * While in TASK_TRACED, we were considered "frozen enough".
1645 * Now that we woke up, it's crucial if we're supposed to be
1646 * frozen that we freeze now before running anything substantial.
1651 * We are back. Now reacquire the siglock before touching
1652 * last_siginfo, so that we are sure to have synchronized with
1653 * any signal-sending on another CPU that wants to examine it.
1655 spin_lock_irq(¤t->sighand->siglock);
1656 current->last_siginfo = NULL;
1659 * Queued signals ignored us while we were stopped for tracing.
1660 * So check for any that we should take before resuming user mode.
1661 * This sets TIF_SIGPENDING, but never clears it.
1663 recalc_sigpending_tsk(current);
1666 void ptrace_notify(int exit_code)
1670 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1672 memset(&info, 0, sizeof info);
1673 info.si_signo = SIGTRAP;
1674 info.si_code = exit_code;
1675 info.si_pid = task_pid_vnr(current);
1676 info.si_uid = current->uid;
1678 /* Let the debugger run. */
1679 spin_lock_irq(¤t->sighand->siglock);
1680 ptrace_stop(exit_code, 1, &info);
1681 spin_unlock_irq(¤t->sighand->siglock);
1685 finish_stop(int stop_count)
1688 * If there are no other threads in the group, or if there is
1689 * a group stop in progress and we are the last to stop,
1690 * report to the parent. When ptraced, every thread reports itself.
1692 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1693 read_lock(&tasklist_lock);
1694 do_notify_parent_cldstop(current, CLD_STOPPED);
1695 read_unlock(&tasklist_lock);
1700 } while (try_to_freeze());
1702 * Now we don't run again until continued.
1704 current->exit_code = 0;
1708 * This performs the stopping for SIGSTOP and other stop signals.
1709 * We have to stop all threads in the thread group.
1710 * Returns nonzero if we've actually stopped and released the siglock.
1711 * Returns zero if we didn't stop and still hold the siglock.
1713 static int do_signal_stop(int signr)
1715 struct signal_struct *sig = current->signal;
1718 if (sig->group_stop_count > 0) {
1720 * There is a group stop in progress. We don't need to
1721 * start another one.
1723 stop_count = --sig->group_stop_count;
1725 struct task_struct *t;
1727 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1728 unlikely(sig->group_exit_task))
1731 * There is no group stop already in progress.
1732 * We must initiate one now.
1734 sig->group_exit_code = signr;
1737 for (t = next_thread(current); t != current; t = next_thread(t))
1739 * Setting state to TASK_STOPPED for a group
1740 * stop is always done with the siglock held,
1741 * so this check has no races.
1743 if (!(t->flags & PF_EXITING) &&
1744 !task_is_stopped_or_traced(t)) {
1746 signal_wake_up(t, 0);
1748 sig->group_stop_count = stop_count;
1751 if (stop_count == 0)
1752 sig->flags = SIGNAL_STOP_STOPPED;
1753 current->exit_code = sig->group_exit_code;
1754 __set_current_state(TASK_STOPPED);
1756 spin_unlock_irq(¤t->sighand->siglock);
1757 finish_stop(stop_count);
1761 static int ptrace_signal(int signr, siginfo_t *info,
1762 struct pt_regs *regs, void *cookie)
1764 if (!(current->ptrace & PT_PTRACED))
1767 ptrace_signal_deliver(regs, cookie);
1769 /* Let the debugger run. */
1770 ptrace_stop(signr, 0, info);
1772 /* We're back. Did the debugger cancel the sig? */
1773 signr = current->exit_code;
1777 current->exit_code = 0;
1779 /* Update the siginfo structure if the signal has
1780 changed. If the debugger wanted something
1781 specific in the siginfo structure then it should
1782 have updated *info via PTRACE_SETSIGINFO. */
1783 if (signr != info->si_signo) {
1784 info->si_signo = signr;
1786 info->si_code = SI_USER;
1787 info->si_pid = task_pid_vnr(current->parent);
1788 info->si_uid = current->parent->uid;
1791 /* If the (new) signal is now blocked, requeue it. */
1792 if (sigismember(¤t->blocked, signr)) {
1793 specific_send_sig_info(signr, info, current);
1800 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1801 struct pt_regs *regs, void *cookie)
1803 sigset_t *mask = ¤t->blocked;
1808 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1809 * While in TASK_STOPPED, we were considered "frozen enough".
1810 * Now that we woke up, it's crucial if we're supposed to be
1811 * frozen that we freeze now before running anything substantial.
1815 spin_lock_irq(¤t->sighand->siglock);
1817 struct k_sigaction *ka;
1819 if (unlikely(current->signal->group_stop_count > 0) &&
1823 signr = dequeue_signal(current, mask, info);
1826 break; /* will return 0 */
1828 if (signr != SIGKILL) {
1829 signr = ptrace_signal(signr, info, regs, cookie);
1834 ka = ¤t->sighand->action[signr-1];
1835 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1837 if (ka->sa.sa_handler != SIG_DFL) {
1838 /* Run the handler. */
1841 if (ka->sa.sa_flags & SA_ONESHOT)
1842 ka->sa.sa_handler = SIG_DFL;
1844 break; /* will return non-zero "signr" value */
1848 * Now we are doing the default action for this signal.
1850 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1854 * Global init gets no signals it doesn't want.
1856 if (is_global_init(current))
1859 if (sig_kernel_stop(signr)) {
1861 * The default action is to stop all threads in
1862 * the thread group. The job control signals
1863 * do nothing in an orphaned pgrp, but SIGSTOP
1864 * always works. Note that siglock needs to be
1865 * dropped during the call to is_orphaned_pgrp()
1866 * because of lock ordering with tasklist_lock.
1867 * This allows an intervening SIGCONT to be posted.
1868 * We need to check for that and bail out if necessary.
1870 if (signr != SIGSTOP) {
1871 spin_unlock_irq(¤t->sighand->siglock);
1873 /* signals can be posted during this window */
1875 if (is_current_pgrp_orphaned())
1878 spin_lock_irq(¤t->sighand->siglock);
1881 if (likely(do_signal_stop(signr))) {
1882 /* It released the siglock. */
1887 * We didn't actually stop, due to a race
1888 * with SIGCONT or something like that.
1893 spin_unlock_irq(¤t->sighand->siglock);
1896 * Anything else is fatal, maybe with a core dump.
1898 current->flags |= PF_SIGNALED;
1899 if ((signr != SIGKILL) && print_fatal_signals)
1900 print_fatal_signal(regs, signr);
1901 if (sig_kernel_coredump(signr)) {
1903 * If it was able to dump core, this kills all
1904 * other threads in the group and synchronizes with
1905 * their demise. If we lost the race with another
1906 * thread getting here, it set group_exit_code
1907 * first and our do_group_exit call below will use
1908 * that value and ignore the one we pass it.
1910 do_coredump((long)signr, signr, regs);
1914 * Death signals, no core dump.
1916 do_group_exit(signr);
1919 spin_unlock_irq(¤t->sighand->siglock);
1923 void exit_signals(struct task_struct *tsk)
1926 struct task_struct *t;
1928 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1929 tsk->flags |= PF_EXITING;
1933 spin_lock_irq(&tsk->sighand->siglock);
1935 * From now this task is not visible for group-wide signals,
1936 * see wants_signal(), do_signal_stop().
1938 tsk->flags |= PF_EXITING;
1939 if (!signal_pending(tsk))
1942 /* It could be that __group_complete_signal() choose us to
1943 * notify about group-wide signal. Another thread should be
1944 * woken now to take the signal since we will not.
1946 for (t = tsk; (t = next_thread(t)) != tsk; )
1947 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1948 recalc_sigpending_and_wake(t);
1950 if (unlikely(tsk->signal->group_stop_count) &&
1951 !--tsk->signal->group_stop_count) {
1952 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1956 spin_unlock_irq(&tsk->sighand->siglock);
1958 if (unlikely(group_stop)) {
1959 read_lock(&tasklist_lock);
1960 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1961 read_unlock(&tasklist_lock);
1965 EXPORT_SYMBOL(recalc_sigpending);
1966 EXPORT_SYMBOL_GPL(dequeue_signal);
1967 EXPORT_SYMBOL(flush_signals);
1968 EXPORT_SYMBOL(force_sig);
1969 EXPORT_SYMBOL(kill_proc);
1970 EXPORT_SYMBOL(ptrace_notify);
1971 EXPORT_SYMBOL(send_sig);
1972 EXPORT_SYMBOL(send_sig_info);
1973 EXPORT_SYMBOL(sigprocmask);
1974 EXPORT_SYMBOL(block_all_signals);
1975 EXPORT_SYMBOL(unblock_all_signals);
1979 * System call entry points.
1982 asmlinkage long sys_restart_syscall(void)
1984 struct restart_block *restart = ¤t_thread_info()->restart_block;
1985 return restart->fn(restart);
1988 long do_no_restart_syscall(struct restart_block *param)
1994 * We don't need to get the kernel lock - this is all local to this
1995 * particular thread.. (and that's good, because this is _heavily_
1996 * used by various programs)
2000 * This is also useful for kernel threads that want to temporarily
2001 * (or permanently) block certain signals.
2003 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2004 * interface happily blocks "unblockable" signals like SIGKILL
2007 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2011 spin_lock_irq(¤t->sighand->siglock);
2013 *oldset = current->blocked;
2018 sigorsets(¤t->blocked, ¤t->blocked, set);
2021 signandsets(¤t->blocked, ¤t->blocked, set);
2024 current->blocked = *set;
2029 recalc_sigpending();
2030 spin_unlock_irq(¤t->sighand->siglock);
2036 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2038 int error = -EINVAL;
2039 sigset_t old_set, new_set;
2041 /* XXX: Don't preclude handling different sized sigset_t's. */
2042 if (sigsetsize != sizeof(sigset_t))
2047 if (copy_from_user(&new_set, set, sizeof(*set)))
2049 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2051 error = sigprocmask(how, &new_set, &old_set);
2057 spin_lock_irq(¤t->sighand->siglock);
2058 old_set = current->blocked;
2059 spin_unlock_irq(¤t->sighand->siglock);
2063 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2071 long do_sigpending(void __user *set, unsigned long sigsetsize)
2073 long error = -EINVAL;
2076 if (sigsetsize > sizeof(sigset_t))
2079 spin_lock_irq(¤t->sighand->siglock);
2080 sigorsets(&pending, ¤t->pending.signal,
2081 ¤t->signal->shared_pending.signal);
2082 spin_unlock_irq(¤t->sighand->siglock);
2084 /* Outside the lock because only this thread touches it. */
2085 sigandsets(&pending, ¤t->blocked, &pending);
2088 if (!copy_to_user(set, &pending, sigsetsize))
2096 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2098 return do_sigpending(set, sigsetsize);
2101 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2103 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2107 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2109 if (from->si_code < 0)
2110 return __copy_to_user(to, from, sizeof(siginfo_t))
2113 * If you change siginfo_t structure, please be sure
2114 * this code is fixed accordingly.
2115 * Please remember to update the signalfd_copyinfo() function
2116 * inside fs/signalfd.c too, in case siginfo_t changes.
2117 * It should never copy any pad contained in the structure
2118 * to avoid security leaks, but must copy the generic
2119 * 3 ints plus the relevant union member.
2121 err = __put_user(from->si_signo, &to->si_signo);
2122 err |= __put_user(from->si_errno, &to->si_errno);
2123 err |= __put_user((short)from->si_code, &to->si_code);
2124 switch (from->si_code & __SI_MASK) {
2126 err |= __put_user(from->si_pid, &to->si_pid);
2127 err |= __put_user(from->si_uid, &to->si_uid);
2130 err |= __put_user(from->si_tid, &to->si_tid);
2131 err |= __put_user(from->si_overrun, &to->si_overrun);
2132 err |= __put_user(from->si_ptr, &to->si_ptr);
2135 err |= __put_user(from->si_band, &to->si_band);
2136 err |= __put_user(from->si_fd, &to->si_fd);
2139 err |= __put_user(from->si_addr, &to->si_addr);
2140 #ifdef __ARCH_SI_TRAPNO
2141 err |= __put_user(from->si_trapno, &to->si_trapno);
2145 err |= __put_user(from->si_pid, &to->si_pid);
2146 err |= __put_user(from->si_uid, &to->si_uid);
2147 err |= __put_user(from->si_status, &to->si_status);
2148 err |= __put_user(from->si_utime, &to->si_utime);
2149 err |= __put_user(from->si_stime, &to->si_stime);
2151 case __SI_RT: /* This is not generated by the kernel as of now. */
2152 case __SI_MESGQ: /* But this is */
2153 err |= __put_user(from->si_pid, &to->si_pid);
2154 err |= __put_user(from->si_uid, &to->si_uid);
2155 err |= __put_user(from->si_ptr, &to->si_ptr);
2157 default: /* this is just in case for now ... */
2158 err |= __put_user(from->si_pid, &to->si_pid);
2159 err |= __put_user(from->si_uid, &to->si_uid);
2168 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2169 siginfo_t __user *uinfo,
2170 const struct timespec __user *uts,
2179 /* XXX: Don't preclude handling different sized sigset_t's. */
2180 if (sigsetsize != sizeof(sigset_t))
2183 if (copy_from_user(&these, uthese, sizeof(these)))
2187 * Invert the set of allowed signals to get those we
2190 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2194 if (copy_from_user(&ts, uts, sizeof(ts)))
2196 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2201 spin_lock_irq(¤t->sighand->siglock);
2202 sig = dequeue_signal(current, &these, &info);
2204 timeout = MAX_SCHEDULE_TIMEOUT;
2206 timeout = (timespec_to_jiffies(&ts)
2207 + (ts.tv_sec || ts.tv_nsec));
2210 /* None ready -- temporarily unblock those we're
2211 * interested while we are sleeping in so that we'll
2212 * be awakened when they arrive. */
2213 current->real_blocked = current->blocked;
2214 sigandsets(¤t->blocked, ¤t->blocked, &these);
2215 recalc_sigpending();
2216 spin_unlock_irq(¤t->sighand->siglock);
2218 timeout = schedule_timeout_interruptible(timeout);
2220 spin_lock_irq(¤t->sighand->siglock);
2221 sig = dequeue_signal(current, &these, &info);
2222 current->blocked = current->real_blocked;
2223 siginitset(¤t->real_blocked, 0);
2224 recalc_sigpending();
2227 spin_unlock_irq(¤t->sighand->siglock);
2232 if (copy_siginfo_to_user(uinfo, &info))
2245 sys_kill(int pid, int sig)
2247 struct siginfo info;
2249 info.si_signo = sig;
2251 info.si_code = SI_USER;
2252 info.si_pid = task_tgid_vnr(current);
2253 info.si_uid = current->uid;
2255 return kill_something_info(sig, &info, pid);
2258 static int do_tkill(int tgid, int pid, int sig)
2261 struct siginfo info;
2262 struct task_struct *p;
2265 info.si_signo = sig;
2267 info.si_code = SI_TKILL;
2268 info.si_pid = task_tgid_vnr(current);
2269 info.si_uid = current->uid;
2271 read_lock(&tasklist_lock);
2272 p = find_task_by_vpid(pid);
2273 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2274 error = check_kill_permission(sig, &info, p);
2276 * The null signal is a permissions and process existence
2277 * probe. No signal is actually delivered.
2279 if (!error && sig && p->sighand) {
2280 spin_lock_irq(&p->sighand->siglock);
2281 handle_stop_signal(sig, p);
2282 error = specific_send_sig_info(sig, &info, p);
2283 spin_unlock_irq(&p->sighand->siglock);
2286 read_unlock(&tasklist_lock);
2292 * sys_tgkill - send signal to one specific thread
2293 * @tgid: the thread group ID of the thread
2294 * @pid: the PID of the thread
2295 * @sig: signal to be sent
2297 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2298 * exists but it's not belonging to the target process anymore. This
2299 * method solves the problem of threads exiting and PIDs getting reused.
2301 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2303 /* This is only valid for single tasks */
2304 if (pid <= 0 || tgid <= 0)
2307 return do_tkill(tgid, pid, sig);
2311 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2314 sys_tkill(int pid, int sig)
2316 /* This is only valid for single tasks */
2320 return do_tkill(0, pid, sig);
2324 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2328 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2331 /* Not even root can pretend to send signals from the kernel.
2332 Nor can they impersonate a kill(), which adds source info. */
2333 if (info.si_code >= 0)
2335 info.si_signo = sig;
2337 /* POSIX.1b doesn't mention process groups. */
2338 return kill_proc_info(sig, &info, pid);
2341 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2343 struct k_sigaction *k;
2346 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2349 k = ¤t->sighand->action[sig-1];
2351 spin_lock_irq(¤t->sighand->siglock);
2356 sigdelsetmask(&act->sa.sa_mask,
2357 sigmask(SIGKILL) | sigmask(SIGSTOP));
2361 * "Setting a signal action to SIG_IGN for a signal that is
2362 * pending shall cause the pending signal to be discarded,
2363 * whether or not it is blocked."
2365 * "Setting a signal action to SIG_DFL for a signal that is
2366 * pending and whose default action is to ignore the signal
2367 * (for example, SIGCHLD), shall cause the pending signal to
2368 * be discarded, whether or not it is blocked"
2370 if (act->sa.sa_handler == SIG_IGN ||
2371 (act->sa.sa_handler == SIG_DFL && sig_kernel_ignore(sig))) {
2372 struct task_struct *t = current;
2374 sigaddset(&mask, sig);
2375 rm_from_queue_full(&mask, &t->signal->shared_pending);
2377 rm_from_queue_full(&mask, &t->pending);
2379 } while (t != current);
2383 spin_unlock_irq(¤t->sighand->siglock);
2388 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2394 oss.ss_sp = (void __user *) current->sas_ss_sp;
2395 oss.ss_size = current->sas_ss_size;
2396 oss.ss_flags = sas_ss_flags(sp);
2405 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2406 || __get_user(ss_sp, &uss->ss_sp)
2407 || __get_user(ss_flags, &uss->ss_flags)
2408 || __get_user(ss_size, &uss->ss_size))
2412 if (on_sig_stack(sp))
2418 * Note - this code used to test ss_flags incorrectly
2419 * old code may have been written using ss_flags==0
2420 * to mean ss_flags==SS_ONSTACK (as this was the only
2421 * way that worked) - this fix preserves that older
2424 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2427 if (ss_flags == SS_DISABLE) {
2432 if (ss_size < MINSIGSTKSZ)
2436 current->sas_ss_sp = (unsigned long) ss_sp;
2437 current->sas_ss_size = ss_size;
2442 if (copy_to_user(uoss, &oss, sizeof(oss)))
2451 #ifdef __ARCH_WANT_SYS_SIGPENDING
2454 sys_sigpending(old_sigset_t __user *set)
2456 return do_sigpending(set, sizeof(*set));
2461 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2462 /* Some platforms have their own version with special arguments others
2463 support only sys_rt_sigprocmask. */
2466 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2469 old_sigset_t old_set, new_set;
2473 if (copy_from_user(&new_set, set, sizeof(*set)))
2475 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2477 spin_lock_irq(¤t->sighand->siglock);
2478 old_set = current->blocked.sig[0];
2486 sigaddsetmask(¤t->blocked, new_set);
2489 sigdelsetmask(¤t->blocked, new_set);
2492 current->blocked.sig[0] = new_set;
2496 recalc_sigpending();
2497 spin_unlock_irq(¤t->sighand->siglock);
2503 old_set = current->blocked.sig[0];
2506 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2513 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2515 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2517 sys_rt_sigaction(int sig,
2518 const struct sigaction __user *act,
2519 struct sigaction __user *oact,
2522 struct k_sigaction new_sa, old_sa;
2525 /* XXX: Don't preclude handling different sized sigset_t's. */
2526 if (sigsetsize != sizeof(sigset_t))
2530 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2534 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2537 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2543 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2545 #ifdef __ARCH_WANT_SYS_SGETMASK
2548 * For backwards compatibility. Functionality superseded by sigprocmask.
2554 return current->blocked.sig[0];
2558 sys_ssetmask(int newmask)
2562 spin_lock_irq(¤t->sighand->siglock);
2563 old = current->blocked.sig[0];
2565 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2567 recalc_sigpending();
2568 spin_unlock_irq(¤t->sighand->siglock);
2572 #endif /* __ARCH_WANT_SGETMASK */
2574 #ifdef __ARCH_WANT_SYS_SIGNAL
2576 * For backwards compatibility. Functionality superseded by sigaction.
2578 asmlinkage unsigned long
2579 sys_signal(int sig, __sighandler_t handler)
2581 struct k_sigaction new_sa, old_sa;
2584 new_sa.sa.sa_handler = handler;
2585 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2586 sigemptyset(&new_sa.sa.sa_mask);
2588 ret = do_sigaction(sig, &new_sa, &old_sa);
2590 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2592 #endif /* __ARCH_WANT_SYS_SIGNAL */
2594 #ifdef __ARCH_WANT_SYS_PAUSE
2599 current->state = TASK_INTERRUPTIBLE;
2601 return -ERESTARTNOHAND;
2606 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2607 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2611 /* XXX: Don't preclude handling different sized sigset_t's. */
2612 if (sigsetsize != sizeof(sigset_t))
2615 if (copy_from_user(&newset, unewset, sizeof(newset)))
2617 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2619 spin_lock_irq(¤t->sighand->siglock);
2620 current->saved_sigmask = current->blocked;
2621 current->blocked = newset;
2622 recalc_sigpending();
2623 spin_unlock_irq(¤t->sighand->siglock);
2625 current->state = TASK_INTERRUPTIBLE;
2627 set_thread_flag(TIF_RESTORE_SIGMASK);
2628 return -ERESTARTNOHAND;
2630 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2632 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2637 void __init signals_init(void)
2639 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);