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/tracehook.h>
26 #include <linux/capability.h>
27 #include <linux/freezer.h>
28 #include <linux/pid_namespace.h>
29 #include <linux/nsproxy.h>
31 #include <asm/param.h>
32 #include <asm/uaccess.h>
33 #include <asm/unistd.h>
34 #include <asm/siginfo.h>
35 #include "audit.h" /* audit_signal_info() */
38 * SLAB caches for signal bits.
41 static struct kmem_cache *sigqueue_cachep;
43 static void __user *sig_handler(struct task_struct *t, int sig)
45 return t->sighand->action[sig - 1].sa.sa_handler;
48 static int sig_handler_ignored(void __user *handler, int sig)
50 /* Is it explicitly or implicitly ignored? */
51 return handler == SIG_IGN ||
52 (handler == SIG_DFL && sig_kernel_ignore(sig));
55 static int sig_ignored(struct task_struct *t, int sig)
60 * Blocked signals are never ignored, since the
61 * signal handler may change by the time it is
64 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
67 handler = sig_handler(t, sig);
68 if (!sig_handler_ignored(handler, sig))
72 * Tracers may want to know about even ignored signals.
74 return !tracehook_consider_ignored_signal(t, sig, handler);
78 * Re-calculate pending state from the set of locally pending
79 * signals, globally pending signals, and blocked signals.
81 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
86 switch (_NSIG_WORDS) {
88 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
89 ready |= signal->sig[i] &~ blocked->sig[i];
92 case 4: ready = signal->sig[3] &~ blocked->sig[3];
93 ready |= signal->sig[2] &~ blocked->sig[2];
94 ready |= signal->sig[1] &~ blocked->sig[1];
95 ready |= signal->sig[0] &~ blocked->sig[0];
98 case 2: ready = signal->sig[1] &~ blocked->sig[1];
99 ready |= signal->sig[0] &~ blocked->sig[0];
102 case 1: ready = signal->sig[0] &~ blocked->sig[0];
107 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
109 static int recalc_sigpending_tsk(struct task_struct *t)
111 if (t->signal->group_stop_count > 0 ||
112 PENDING(&t->pending, &t->blocked) ||
113 PENDING(&t->signal->shared_pending, &t->blocked)) {
114 set_tsk_thread_flag(t, TIF_SIGPENDING);
118 * We must never clear the flag in another thread, or in current
119 * when it's possible the current syscall is returning -ERESTART*.
120 * So we don't clear it here, and only callers who know they should do.
126 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
127 * This is superfluous when called on current, the wakeup is a harmless no-op.
129 void recalc_sigpending_and_wake(struct task_struct *t)
131 if (recalc_sigpending_tsk(t))
132 signal_wake_up(t, 0);
135 void recalc_sigpending(void)
137 if (!recalc_sigpending_tsk(current) && !freezing(current))
138 clear_thread_flag(TIF_SIGPENDING);
142 /* Given the mask, find the first available signal that should be serviced. */
144 int next_signal(struct sigpending *pending, sigset_t *mask)
146 unsigned long i, *s, *m, x;
149 s = pending->signal.sig;
151 switch (_NSIG_WORDS) {
153 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
154 if ((x = *s &~ *m) != 0) {
155 sig = ffz(~x) + i*_NSIG_BPW + 1;
160 case 2: if ((x = s[0] &~ m[0]) != 0)
162 else if ((x = s[1] &~ m[1]) != 0)
169 case 1: if ((x = *s &~ *m) != 0)
177 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
180 struct sigqueue *q = NULL;
181 struct user_struct *user;
184 * In order to avoid problems with "switch_user()", we want to make
185 * sure that the compiler doesn't re-load "t->user"
189 atomic_inc(&user->sigpending);
190 if (override_rlimit ||
191 atomic_read(&user->sigpending) <=
192 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
193 q = kmem_cache_alloc(sigqueue_cachep, flags);
194 if (unlikely(q == NULL)) {
195 atomic_dec(&user->sigpending);
197 INIT_LIST_HEAD(&q->list);
199 q->user = get_uid(user);
204 static void __sigqueue_free(struct sigqueue *q)
206 if (q->flags & SIGQUEUE_PREALLOC)
208 atomic_dec(&q->user->sigpending);
210 kmem_cache_free(sigqueue_cachep, q);
213 void flush_sigqueue(struct sigpending *queue)
217 sigemptyset(&queue->signal);
218 while (!list_empty(&queue->list)) {
219 q = list_entry(queue->list.next, struct sigqueue , list);
220 list_del_init(&q->list);
226 * Flush all pending signals for a task.
228 void flush_signals(struct task_struct *t)
232 spin_lock_irqsave(&t->sighand->siglock, flags);
233 clear_tsk_thread_flag(t, TIF_SIGPENDING);
234 flush_sigqueue(&t->pending);
235 flush_sigqueue(&t->signal->shared_pending);
236 spin_unlock_irqrestore(&t->sighand->siglock, flags);
239 static void __flush_itimer_signals(struct sigpending *pending)
241 sigset_t signal, retain;
242 struct sigqueue *q, *n;
244 signal = pending->signal;
245 sigemptyset(&retain);
247 list_for_each_entry_safe(q, n, &pending->list, list) {
248 int sig = q->info.si_signo;
250 if (likely(q->info.si_code != SI_TIMER)) {
251 sigaddset(&retain, sig);
253 sigdelset(&signal, sig);
254 list_del_init(&q->list);
259 sigorsets(&pending->signal, &signal, &retain);
262 void flush_itimer_signals(void)
264 struct task_struct *tsk = current;
267 spin_lock_irqsave(&tsk->sighand->siglock, flags);
268 __flush_itimer_signals(&tsk->pending);
269 __flush_itimer_signals(&tsk->signal->shared_pending);
270 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
273 void ignore_signals(struct task_struct *t)
277 for (i = 0; i < _NSIG; ++i)
278 t->sighand->action[i].sa.sa_handler = SIG_IGN;
284 * Flush all handlers for a task.
288 flush_signal_handlers(struct task_struct *t, int force_default)
291 struct k_sigaction *ka = &t->sighand->action[0];
292 for (i = _NSIG ; i != 0 ; i--) {
293 if (force_default || ka->sa.sa_handler != SIG_IGN)
294 ka->sa.sa_handler = SIG_DFL;
296 sigemptyset(&ka->sa.sa_mask);
301 int unhandled_signal(struct task_struct *tsk, int sig)
303 if (is_global_init(tsk))
305 if (tsk->ptrace & PT_PTRACED)
307 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
308 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
312 /* Notify the system that a driver wants to block all signals for this
313 * process, and wants to be notified if any signals at all were to be
314 * sent/acted upon. If the notifier routine returns non-zero, then the
315 * signal will be acted upon after all. If the notifier routine returns 0,
316 * then then signal will be blocked. Only one block per process is
317 * allowed. priv is a pointer to private data that the notifier routine
318 * can use to determine if the signal should be blocked or not. */
321 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
325 spin_lock_irqsave(¤t->sighand->siglock, flags);
326 current->notifier_mask = mask;
327 current->notifier_data = priv;
328 current->notifier = notifier;
329 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
332 /* Notify the system that blocking has ended. */
335 unblock_all_signals(void)
339 spin_lock_irqsave(¤t->sighand->siglock, flags);
340 current->notifier = NULL;
341 current->notifier_data = NULL;
343 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
346 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
348 struct sigqueue *q, *first = NULL;
351 * Collect the siginfo appropriate to this signal. Check if
352 * there is another siginfo for the same signal.
354 list_for_each_entry(q, &list->list, list) {
355 if (q->info.si_signo == sig) {
362 sigdelset(&list->signal, sig);
366 list_del_init(&first->list);
367 copy_siginfo(info, &first->info);
368 __sigqueue_free(first);
370 /* Ok, it wasn't in the queue. This must be
371 a fast-pathed signal or we must have been
372 out of queue space. So zero out the info.
374 info->si_signo = sig;
382 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
385 int sig = next_signal(pending, mask);
388 if (current->notifier) {
389 if (sigismember(current->notifier_mask, sig)) {
390 if (!(current->notifier)(current->notifier_data)) {
391 clear_thread_flag(TIF_SIGPENDING);
397 collect_signal(sig, pending, info);
404 * Dequeue a signal and return the element to the caller, which is
405 * expected to free it.
407 * All callers have to hold the siglock.
409 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
413 /* We only dequeue private signals from ourselves, we don't let
414 * signalfd steal them
416 signr = __dequeue_signal(&tsk->pending, mask, info);
418 signr = __dequeue_signal(&tsk->signal->shared_pending,
423 * itimers are process shared and we restart periodic
424 * itimers in the signal delivery path to prevent DoS
425 * attacks in the high resolution timer case. This is
426 * compliant with the old way of self restarting
427 * itimers, as the SIGALRM is a legacy signal and only
428 * queued once. Changing the restart behaviour to
429 * restart the timer in the signal dequeue path is
430 * reducing the timer noise on heavy loaded !highres
433 if (unlikely(signr == SIGALRM)) {
434 struct hrtimer *tmr = &tsk->signal->real_timer;
436 if (!hrtimer_is_queued(tmr) &&
437 tsk->signal->it_real_incr.tv64 != 0) {
438 hrtimer_forward(tmr, tmr->base->get_time(),
439 tsk->signal->it_real_incr);
440 hrtimer_restart(tmr);
449 if (unlikely(sig_kernel_stop(signr))) {
451 * Set a marker that we have dequeued a stop signal. Our
452 * caller might release the siglock and then the pending
453 * stop signal it is about to process is no longer in the
454 * pending bitmasks, but must still be cleared by a SIGCONT
455 * (and overruled by a SIGKILL). So those cases clear this
456 * shared flag after we've set it. Note that this flag may
457 * remain set after the signal we return is ignored or
458 * handled. That doesn't matter because its only purpose
459 * is to alert stop-signal processing code when another
460 * processor has come along and cleared the flag.
462 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
464 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
466 * Release the siglock to ensure proper locking order
467 * of timer locks outside of siglocks. Note, we leave
468 * irqs disabled here, since the posix-timers code is
469 * about to disable them again anyway.
471 spin_unlock(&tsk->sighand->siglock);
472 do_schedule_next_timer(info);
473 spin_lock(&tsk->sighand->siglock);
479 * Tell a process that it has a new active signal..
481 * NOTE! we rely on the previous spin_lock to
482 * lock interrupts for us! We can only be called with
483 * "siglock" held, and the local interrupt must
484 * have been disabled when that got acquired!
486 * No need to set need_resched since signal event passing
487 * goes through ->blocked
489 void signal_wake_up(struct task_struct *t, int resume)
493 set_tsk_thread_flag(t, TIF_SIGPENDING);
496 * For SIGKILL, we want to wake it up in the stopped/traced/killable
497 * case. We don't check t->state here because there is a race with it
498 * executing another processor and just now entering stopped state.
499 * By using wake_up_state, we ensure the process will wake up and
500 * handle its death signal.
502 mask = TASK_INTERRUPTIBLE;
504 mask |= TASK_WAKEKILL;
505 if (!wake_up_state(t, mask))
510 * Remove signals in mask from the pending set and queue.
511 * Returns 1 if any signals were found.
513 * All callers must be holding the siglock.
515 * This version takes a sigset mask and looks at all signals,
516 * not just those in the first mask word.
518 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
520 struct sigqueue *q, *n;
523 sigandsets(&m, mask, &s->signal);
524 if (sigisemptyset(&m))
527 signandsets(&s->signal, &s->signal, mask);
528 list_for_each_entry_safe(q, n, &s->list, list) {
529 if (sigismember(mask, q->info.si_signo)) {
530 list_del_init(&q->list);
537 * Remove signals in mask from the pending set and queue.
538 * Returns 1 if any signals were found.
540 * All callers must be holding the siglock.
542 static int rm_from_queue(unsigned long mask, struct sigpending *s)
544 struct sigqueue *q, *n;
546 if (!sigtestsetmask(&s->signal, mask))
549 sigdelsetmask(&s->signal, mask);
550 list_for_each_entry_safe(q, n, &s->list, list) {
551 if (q->info.si_signo < SIGRTMIN &&
552 (mask & sigmask(q->info.si_signo))) {
553 list_del_init(&q->list);
561 * Bad permissions for sending the signal
563 static int check_kill_permission(int sig, struct siginfo *info,
564 struct task_struct *t)
569 if (!valid_signal(sig))
572 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
575 error = audit_signal_info(sig, t); /* Let audit system see the signal */
579 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
580 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
581 !capable(CAP_KILL)) {
584 sid = task_session(t);
586 * We don't return the error if sid == NULL. The
587 * task was unhashed, the caller must notice this.
589 if (!sid || sid == task_session(current))
596 return security_task_kill(t, info, sig, 0);
600 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
603 * Handle magic process-wide effects of stop/continue signals. Unlike
604 * the signal actions, these happen immediately at signal-generation
605 * time regardless of blocking, ignoring, or handling. This does the
606 * actual continuing for SIGCONT, but not the actual stopping for stop
607 * signals. The process stop is done as a signal action for SIG_DFL.
609 * Returns true if the signal should be actually delivered, otherwise
610 * it should be dropped.
612 static int prepare_signal(int sig, struct task_struct *p)
614 struct signal_struct *signal = p->signal;
615 struct task_struct *t;
617 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
619 * The process is in the middle of dying, nothing to do.
621 } else if (sig_kernel_stop(sig)) {
623 * This is a stop signal. Remove SIGCONT from all queues.
625 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
628 rm_from_queue(sigmask(SIGCONT), &t->pending);
629 } while_each_thread(p, t);
630 } else if (sig == SIGCONT) {
633 * Remove all stop signals from all queues,
634 * and wake all threads.
636 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
640 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
642 * If there is a handler for SIGCONT, we must make
643 * sure that no thread returns to user mode before
644 * we post the signal, in case it was the only
645 * thread eligible to run the signal handler--then
646 * it must not do anything between resuming and
647 * running the handler. With the TIF_SIGPENDING
648 * flag set, the thread will pause and acquire the
649 * siglock that we hold now and until we've queued
650 * the pending signal.
652 * Wake up the stopped thread _after_ setting
655 state = __TASK_STOPPED;
656 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
657 set_tsk_thread_flag(t, TIF_SIGPENDING);
658 state |= TASK_INTERRUPTIBLE;
660 wake_up_state(t, state);
661 } while_each_thread(p, t);
664 * Notify the parent with CLD_CONTINUED if we were stopped.
666 * If we were in the middle of a group stop, we pretend it
667 * was already finished, and then continued. Since SIGCHLD
668 * doesn't queue we report only CLD_STOPPED, as if the next
669 * CLD_CONTINUED was dropped.
672 if (signal->flags & SIGNAL_STOP_STOPPED)
673 why |= SIGNAL_CLD_CONTINUED;
674 else if (signal->group_stop_count)
675 why |= SIGNAL_CLD_STOPPED;
679 * The first thread which returns from finish_stop()
680 * will take ->siglock, notice SIGNAL_CLD_MASK, and
681 * notify its parent. See get_signal_to_deliver().
683 signal->flags = why | SIGNAL_STOP_CONTINUED;
684 signal->group_stop_count = 0;
685 signal->group_exit_code = 0;
688 * We are not stopped, but there could be a stop
689 * signal in the middle of being processed after
690 * being removed from the queue. Clear that too.
692 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
696 return !sig_ignored(p, sig);
700 * Test if P wants to take SIG. After we've checked all threads with this,
701 * it's equivalent to finding no threads not blocking SIG. Any threads not
702 * blocking SIG were ruled out because they are not running and already
703 * have pending signals. Such threads will dequeue from the shared queue
704 * as soon as they're available, so putting the signal on the shared queue
705 * will be equivalent to sending it to one such thread.
707 static inline int wants_signal(int sig, struct task_struct *p)
709 if (sigismember(&p->blocked, sig))
711 if (p->flags & PF_EXITING)
715 if (task_is_stopped_or_traced(p))
717 return task_curr(p) || !signal_pending(p);
720 static void complete_signal(int sig, struct task_struct *p, int group)
722 struct signal_struct *signal = p->signal;
723 struct task_struct *t;
726 * Now find a thread we can wake up to take the signal off the queue.
728 * If the main thread wants the signal, it gets first crack.
729 * Probably the least surprising to the average bear.
731 if (wants_signal(sig, p))
733 else if (!group || thread_group_empty(p))
735 * There is just one thread and it does not need to be woken.
736 * It will dequeue unblocked signals before it runs again.
741 * Otherwise try to find a suitable thread.
743 t = signal->curr_target;
744 while (!wants_signal(sig, t)) {
746 if (t == signal->curr_target)
748 * No thread needs to be woken.
749 * Any eligible threads will see
750 * the signal in the queue soon.
754 signal->curr_target = t;
758 * Found a killable thread. If the signal will be fatal,
759 * then start taking the whole group down immediately.
761 if (sig_fatal(p, sig) &&
762 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
763 !sigismember(&t->real_blocked, sig) &&
764 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
766 * This signal will be fatal to the whole group.
768 if (!sig_kernel_coredump(sig)) {
770 * Start a group exit and wake everybody up.
771 * This way we don't have other threads
772 * running and doing things after a slower
773 * thread has the fatal signal pending.
775 signal->flags = SIGNAL_GROUP_EXIT;
776 signal->group_exit_code = sig;
777 signal->group_stop_count = 0;
780 sigaddset(&t->pending.signal, SIGKILL);
781 signal_wake_up(t, 1);
782 } while_each_thread(p, t);
788 * The signal is already in the shared-pending queue.
789 * Tell the chosen thread to wake up and dequeue it.
791 signal_wake_up(t, sig == SIGKILL);
795 static inline int legacy_queue(struct sigpending *signals, int sig)
797 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
800 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
803 struct sigpending *pending;
806 assert_spin_locked(&t->sighand->siglock);
807 if (!prepare_signal(sig, t))
810 pending = group ? &t->signal->shared_pending : &t->pending;
812 * Short-circuit ignored signals and support queuing
813 * exactly one non-rt signal, so that we can get more
814 * detailed information about the cause of the signal.
816 if (legacy_queue(pending, sig))
819 * fast-pathed signals for kernel-internal things like SIGSTOP
822 if (info == SEND_SIG_FORCED)
825 /* Real-time signals must be queued if sent by sigqueue, or
826 some other real-time mechanism. It is implementation
827 defined whether kill() does so. We attempt to do so, on
828 the principle of least surprise, but since kill is not
829 allowed to fail with EAGAIN when low on memory we just
830 make sure at least one signal gets delivered and don't
831 pass on the info struct. */
833 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
834 (is_si_special(info) ||
835 info->si_code >= 0)));
837 list_add_tail(&q->list, &pending->list);
838 switch ((unsigned long) info) {
839 case (unsigned long) SEND_SIG_NOINFO:
840 q->info.si_signo = sig;
841 q->info.si_errno = 0;
842 q->info.si_code = SI_USER;
843 q->info.si_pid = task_pid_vnr(current);
844 q->info.si_uid = current->uid;
846 case (unsigned long) SEND_SIG_PRIV:
847 q->info.si_signo = sig;
848 q->info.si_errno = 0;
849 q->info.si_code = SI_KERNEL;
854 copy_siginfo(&q->info, info);
857 } else if (!is_si_special(info)) {
858 if (sig >= SIGRTMIN && info->si_code != SI_USER)
860 * Queue overflow, abort. We may abort if the signal was rt
861 * and sent by user using something other than kill().
867 signalfd_notify(t, sig);
868 sigaddset(&pending->signal, sig);
869 complete_signal(sig, t, group);
873 int print_fatal_signals;
875 static void print_fatal_signal(struct pt_regs *regs, int signr)
877 printk("%s/%d: potentially unexpected fatal signal %d.\n",
878 current->comm, task_pid_nr(current), signr);
880 #if defined(__i386__) && !defined(__arch_um__)
881 printk("code at %08lx: ", regs->ip);
884 for (i = 0; i < 16; i++) {
887 __get_user(insn, (unsigned char *)(regs->ip + i));
888 printk("%02x ", insn);
896 static int __init setup_print_fatal_signals(char *str)
898 get_option (&str, &print_fatal_signals);
903 __setup("print-fatal-signals=", setup_print_fatal_signals);
906 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
908 return send_signal(sig, info, p, 1);
912 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
914 return send_signal(sig, info, t, 0);
918 * Force a signal that the process can't ignore: if necessary
919 * we unblock the signal and change any SIG_IGN to SIG_DFL.
921 * Note: If we unblock the signal, we always reset it to SIG_DFL,
922 * since we do not want to have a signal handler that was blocked
923 * be invoked when user space had explicitly blocked it.
925 * We don't want to have recursive SIGSEGV's etc, for example,
926 * that is why we also clear SIGNAL_UNKILLABLE.
929 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
931 unsigned long int flags;
932 int ret, blocked, ignored;
933 struct k_sigaction *action;
935 spin_lock_irqsave(&t->sighand->siglock, flags);
936 action = &t->sighand->action[sig-1];
937 ignored = action->sa.sa_handler == SIG_IGN;
938 blocked = sigismember(&t->blocked, sig);
939 if (blocked || ignored) {
940 action->sa.sa_handler = SIG_DFL;
942 sigdelset(&t->blocked, sig);
943 recalc_sigpending_and_wake(t);
946 if (action->sa.sa_handler == SIG_DFL)
947 t->signal->flags &= ~SIGNAL_UNKILLABLE;
948 ret = specific_send_sig_info(sig, info, t);
949 spin_unlock_irqrestore(&t->sighand->siglock, flags);
955 force_sig_specific(int sig, struct task_struct *t)
957 force_sig_info(sig, SEND_SIG_FORCED, t);
961 * Nuke all other threads in the group.
963 void zap_other_threads(struct task_struct *p)
965 struct task_struct *t;
967 p->signal->group_stop_count = 0;
969 for (t = next_thread(p); t != p; t = next_thread(t)) {
971 * Don't bother with already dead threads
976 /* SIGKILL will be handled before any pending SIGSTOP */
977 sigaddset(&t->pending.signal, SIGKILL);
978 signal_wake_up(t, 1);
982 int __fatal_signal_pending(struct task_struct *tsk)
984 return sigismember(&tsk->pending.signal, SIGKILL);
986 EXPORT_SYMBOL(__fatal_signal_pending);
988 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
990 struct sighand_struct *sighand;
994 sighand = rcu_dereference(tsk->sighand);
995 if (unlikely(sighand == NULL))
998 spin_lock_irqsave(&sighand->siglock, *flags);
999 if (likely(sighand == tsk->sighand))
1001 spin_unlock_irqrestore(&sighand->siglock, *flags);
1008 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1010 unsigned long flags;
1013 ret = check_kill_permission(sig, info, p);
1017 if (lock_task_sighand(p, &flags)) {
1018 ret = __group_send_sig_info(sig, info, p);
1019 unlock_task_sighand(p, &flags);
1027 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1028 * control characters do (^C, ^Z etc)
1031 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1033 struct task_struct *p = NULL;
1034 int retval, success;
1038 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1039 int err = group_send_sig_info(sig, info, p);
1042 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1043 return success ? 0 : retval;
1046 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1049 struct task_struct *p;
1053 p = pid_task(pid, PIDTYPE_PID);
1055 error = group_send_sig_info(sig, info, p);
1056 if (unlikely(error == -ESRCH))
1058 * The task was unhashed in between, try again.
1059 * If it is dead, pid_task() will return NULL,
1060 * if we race with de_thread() it will find the
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, pid_t 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 * The caller must ensure the task can't exit.
1166 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1169 unsigned long flags;
1172 * Make sure legacy kernel users don't send in bad values
1173 * (normal paths check this in check_kill_permission).
1175 if (!valid_signal(sig))
1178 spin_lock_irqsave(&p->sighand->siglock, flags);
1179 ret = specific_send_sig_info(sig, info, p);
1180 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1184 #define __si_special(priv) \
1185 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1188 send_sig(int sig, struct task_struct *p, int priv)
1190 return send_sig_info(sig, __si_special(priv), p);
1194 force_sig(int sig, struct task_struct *p)
1196 force_sig_info(sig, SEND_SIG_PRIV, p);
1200 * When things go south during signal handling, we
1201 * will force a SIGSEGV. And if the signal that caused
1202 * the problem was already a SIGSEGV, we'll want to
1203 * make sure we don't even try to deliver the signal..
1206 force_sigsegv(int sig, struct task_struct *p)
1208 if (sig == SIGSEGV) {
1209 unsigned long flags;
1210 spin_lock_irqsave(&p->sighand->siglock, flags);
1211 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1212 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1214 force_sig(SIGSEGV, p);
1218 int kill_pgrp(struct pid *pid, int sig, int priv)
1222 read_lock(&tasklist_lock);
1223 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1224 read_unlock(&tasklist_lock);
1228 EXPORT_SYMBOL(kill_pgrp);
1230 int kill_pid(struct pid *pid, int sig, int priv)
1232 return kill_pid_info(sig, __si_special(priv), pid);
1234 EXPORT_SYMBOL(kill_pid);
1237 * These functions support sending signals using preallocated sigqueue
1238 * structures. This is needed "because realtime applications cannot
1239 * afford to lose notifications of asynchronous events, like timer
1240 * expirations or I/O completions". In the case of Posix Timers
1241 * we allocate the sigqueue structure from the timer_create. If this
1242 * allocation fails we are able to report the failure to the application
1243 * with an EAGAIN error.
1246 struct sigqueue *sigqueue_alloc(void)
1250 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1251 q->flags |= SIGQUEUE_PREALLOC;
1255 void sigqueue_free(struct sigqueue *q)
1257 unsigned long flags;
1258 spinlock_t *lock = ¤t->sighand->siglock;
1260 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1262 * We must hold ->siglock while testing q->list
1263 * to serialize with collect_signal() or with
1264 * __exit_signal()->flush_sigqueue().
1266 spin_lock_irqsave(lock, flags);
1267 q->flags &= ~SIGQUEUE_PREALLOC;
1269 * If it is queued it will be freed when dequeued,
1270 * like the "regular" sigqueue.
1272 if (!list_empty(&q->list))
1274 spin_unlock_irqrestore(lock, flags);
1280 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1282 int sig = q->info.si_signo;
1283 struct sigpending *pending;
1284 unsigned long flags;
1287 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1290 if (!likely(lock_task_sighand(t, &flags)))
1293 ret = 1; /* the signal is ignored */
1294 if (!prepare_signal(sig, t))
1298 if (unlikely(!list_empty(&q->list))) {
1300 * If an SI_TIMER entry is already queue just increment
1301 * the overrun count.
1303 BUG_ON(q->info.si_code != SI_TIMER);
1304 q->info.si_overrun++;
1308 signalfd_notify(t, sig);
1309 pending = group ? &t->signal->shared_pending : &t->pending;
1310 list_add_tail(&q->list, &pending->list);
1311 sigaddset(&pending->signal, sig);
1312 complete_signal(sig, t, group);
1314 unlock_task_sighand(t, &flags);
1320 * Wake up any threads in the parent blocked in wait* syscalls.
1322 static inline void __wake_up_parent(struct task_struct *p,
1323 struct task_struct *parent)
1325 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1329 * Let a parent know about the death of a child.
1330 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1333 void do_notify_parent(struct task_struct *tsk, int sig)
1335 struct siginfo info;
1336 unsigned long flags;
1337 struct sighand_struct *psig;
1341 /* do_notify_parent_cldstop should have been called instead. */
1342 BUG_ON(task_is_stopped_or_traced(tsk));
1344 BUG_ON(!tsk->ptrace &&
1345 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1347 info.si_signo = sig;
1350 * we are under tasklist_lock here so our parent is tied to
1351 * us and cannot exit and release its namespace.
1353 * the only it can is to switch its nsproxy with sys_unshare,
1354 * bu uncharing pid namespaces is not allowed, so we'll always
1355 * see relevant namespace
1357 * write_lock() currently calls preempt_disable() which is the
1358 * same as rcu_read_lock(), but according to Oleg, this is not
1359 * correct to rely on this
1362 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1365 info.si_uid = tsk->uid;
1367 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1368 tsk->signal->utime));
1369 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1370 tsk->signal->stime));
1372 info.si_status = tsk->exit_code & 0x7f;
1373 if (tsk->exit_code & 0x80)
1374 info.si_code = CLD_DUMPED;
1375 else if (tsk->exit_code & 0x7f)
1376 info.si_code = CLD_KILLED;
1378 info.si_code = CLD_EXITED;
1379 info.si_status = tsk->exit_code >> 8;
1382 psig = tsk->parent->sighand;
1383 spin_lock_irqsave(&psig->siglock, flags);
1384 if (!tsk->ptrace && sig == SIGCHLD &&
1385 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1386 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1388 * We are exiting and our parent doesn't care. POSIX.1
1389 * defines special semantics for setting SIGCHLD to SIG_IGN
1390 * or setting the SA_NOCLDWAIT flag: we should be reaped
1391 * automatically and not left for our parent's wait4 call.
1392 * Rather than having the parent do it as a magic kind of
1393 * signal handler, we just set this to tell do_exit that we
1394 * can be cleaned up without becoming a zombie. Note that
1395 * we still call __wake_up_parent in this case, because a
1396 * blocked sys_wait4 might now return -ECHILD.
1398 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1399 * is implementation-defined: we do (if you don't want
1400 * it, just use SIG_IGN instead).
1402 tsk->exit_signal = -1;
1403 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1406 if (valid_signal(sig) && sig > 0)
1407 __group_send_sig_info(sig, &info, tsk->parent);
1408 __wake_up_parent(tsk, tsk->parent);
1409 spin_unlock_irqrestore(&psig->siglock, flags);
1412 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1414 struct siginfo info;
1415 unsigned long flags;
1416 struct task_struct *parent;
1417 struct sighand_struct *sighand;
1419 if (tsk->ptrace & PT_PTRACED)
1420 parent = tsk->parent;
1422 tsk = tsk->group_leader;
1423 parent = tsk->real_parent;
1426 info.si_signo = SIGCHLD;
1429 * see comment in do_notify_parent() abot the following 3 lines
1432 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1435 info.si_uid = tsk->uid;
1437 info.si_utime = cputime_to_clock_t(tsk->utime);
1438 info.si_stime = cputime_to_clock_t(tsk->stime);
1443 info.si_status = SIGCONT;
1446 info.si_status = tsk->signal->group_exit_code & 0x7f;
1449 info.si_status = tsk->exit_code & 0x7f;
1455 sighand = parent->sighand;
1456 spin_lock_irqsave(&sighand->siglock, flags);
1457 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1458 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1459 __group_send_sig_info(SIGCHLD, &info, parent);
1461 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1463 __wake_up_parent(tsk, parent);
1464 spin_unlock_irqrestore(&sighand->siglock, flags);
1467 static inline int may_ptrace_stop(void)
1469 if (!likely(current->ptrace & PT_PTRACED))
1472 * Are we in the middle of do_coredump?
1473 * If so and our tracer is also part of the coredump stopping
1474 * is a deadlock situation, and pointless because our tracer
1475 * is dead so don't allow us to stop.
1476 * If SIGKILL was already sent before the caller unlocked
1477 * ->siglock we must see ->core_state != NULL. Otherwise it
1478 * is safe to enter schedule().
1480 if (unlikely(current->mm->core_state) &&
1481 unlikely(current->mm == current->parent->mm))
1488 * Return nonzero if there is a SIGKILL that should be waking us up.
1489 * Called with the siglock held.
1491 static int sigkill_pending(struct task_struct *tsk)
1493 return sigismember(&tsk->pending.signal, SIGKILL) ||
1494 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1498 * This must be called with current->sighand->siglock held.
1500 * This should be the path for all ptrace stops.
1501 * We always set current->last_siginfo while stopped here.
1502 * That makes it a way to test a stopped process for
1503 * being ptrace-stopped vs being job-control-stopped.
1505 * If we actually decide not to stop at all because the tracer
1506 * is gone, we keep current->exit_code unless clear_code.
1508 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1510 if (arch_ptrace_stop_needed(exit_code, info)) {
1512 * The arch code has something special to do before a
1513 * ptrace stop. This is allowed to block, e.g. for faults
1514 * on user stack pages. We can't keep the siglock while
1515 * calling arch_ptrace_stop, so we must release it now.
1516 * To preserve proper semantics, we must do this before
1517 * any signal bookkeeping like checking group_stop_count.
1518 * Meanwhile, a SIGKILL could come in before we retake the
1519 * siglock. That must prevent us from sleeping in TASK_TRACED.
1520 * So after regaining the lock, we must check for SIGKILL.
1522 spin_unlock_irq(¤t->sighand->siglock);
1523 arch_ptrace_stop(exit_code, info);
1524 spin_lock_irq(¤t->sighand->siglock);
1525 if (sigkill_pending(current))
1530 * If there is a group stop in progress,
1531 * we must participate in the bookkeeping.
1533 if (current->signal->group_stop_count > 0)
1534 --current->signal->group_stop_count;
1536 current->last_siginfo = info;
1537 current->exit_code = exit_code;
1539 /* Let the debugger run. */
1540 __set_current_state(TASK_TRACED);
1541 spin_unlock_irq(¤t->sighand->siglock);
1542 read_lock(&tasklist_lock);
1543 if (may_ptrace_stop()) {
1544 do_notify_parent_cldstop(current, CLD_TRAPPED);
1545 read_unlock(&tasklist_lock);
1549 * By the time we got the lock, our tracer went away.
1550 * Don't drop the lock yet, another tracer may come.
1552 __set_current_state(TASK_RUNNING);
1554 current->exit_code = 0;
1555 read_unlock(&tasklist_lock);
1559 * While in TASK_TRACED, we were considered "frozen enough".
1560 * Now that we woke up, it's crucial if we're supposed to be
1561 * frozen that we freeze now before running anything substantial.
1566 * We are back. Now reacquire the siglock before touching
1567 * last_siginfo, so that we are sure to have synchronized with
1568 * any signal-sending on another CPU that wants to examine it.
1570 spin_lock_irq(¤t->sighand->siglock);
1571 current->last_siginfo = NULL;
1574 * Queued signals ignored us while we were stopped for tracing.
1575 * So check for any that we should take before resuming user mode.
1576 * This sets TIF_SIGPENDING, but never clears it.
1578 recalc_sigpending_tsk(current);
1581 void ptrace_notify(int exit_code)
1585 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1587 memset(&info, 0, sizeof info);
1588 info.si_signo = SIGTRAP;
1589 info.si_code = exit_code;
1590 info.si_pid = task_pid_vnr(current);
1591 info.si_uid = current->uid;
1593 /* Let the debugger run. */
1594 spin_lock_irq(¤t->sighand->siglock);
1595 ptrace_stop(exit_code, 1, &info);
1596 spin_unlock_irq(¤t->sighand->siglock);
1600 finish_stop(int stop_count)
1603 * If there are no other threads in the group, or if there is
1604 * a group stop in progress and we are the last to stop,
1605 * report to the parent. When ptraced, every thread reports itself.
1607 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1608 read_lock(&tasklist_lock);
1609 do_notify_parent_cldstop(current, CLD_STOPPED);
1610 read_unlock(&tasklist_lock);
1615 } while (try_to_freeze());
1617 * Now we don't run again until continued.
1619 current->exit_code = 0;
1623 * This performs the stopping for SIGSTOP and other stop signals.
1624 * We have to stop all threads in the thread group.
1625 * Returns nonzero if we've actually stopped and released the siglock.
1626 * Returns zero if we didn't stop and still hold the siglock.
1628 static int do_signal_stop(int signr)
1630 struct signal_struct *sig = current->signal;
1633 if (sig->group_stop_count > 0) {
1635 * There is a group stop in progress. We don't need to
1636 * start another one.
1638 stop_count = --sig->group_stop_count;
1640 struct task_struct *t;
1642 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1643 unlikely(signal_group_exit(sig)))
1646 * There is no group stop already in progress.
1647 * We must initiate one now.
1649 sig->group_exit_code = signr;
1652 for (t = next_thread(current); t != current; t = next_thread(t))
1654 * Setting state to TASK_STOPPED for a group
1655 * stop is always done with the siglock held,
1656 * so this check has no races.
1658 if (!(t->flags & PF_EXITING) &&
1659 !task_is_stopped_or_traced(t)) {
1661 signal_wake_up(t, 0);
1663 sig->group_stop_count = stop_count;
1666 if (stop_count == 0)
1667 sig->flags = SIGNAL_STOP_STOPPED;
1668 current->exit_code = sig->group_exit_code;
1669 __set_current_state(TASK_STOPPED);
1671 spin_unlock_irq(¤t->sighand->siglock);
1672 finish_stop(stop_count);
1676 static int ptrace_signal(int signr, siginfo_t *info,
1677 struct pt_regs *regs, void *cookie)
1679 if (!(current->ptrace & PT_PTRACED))
1682 ptrace_signal_deliver(regs, cookie);
1684 /* Let the debugger run. */
1685 ptrace_stop(signr, 0, info);
1687 /* We're back. Did the debugger cancel the sig? */
1688 signr = current->exit_code;
1692 current->exit_code = 0;
1694 /* Update the siginfo structure if the signal has
1695 changed. If the debugger wanted something
1696 specific in the siginfo structure then it should
1697 have updated *info via PTRACE_SETSIGINFO. */
1698 if (signr != info->si_signo) {
1699 info->si_signo = signr;
1701 info->si_code = SI_USER;
1702 info->si_pid = task_pid_vnr(current->parent);
1703 info->si_uid = current->parent->uid;
1706 /* If the (new) signal is now blocked, requeue it. */
1707 if (sigismember(¤t->blocked, signr)) {
1708 specific_send_sig_info(signr, info, current);
1715 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1716 struct pt_regs *regs, void *cookie)
1718 struct sighand_struct *sighand = current->sighand;
1719 struct signal_struct *signal = current->signal;
1724 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1725 * While in TASK_STOPPED, we were considered "frozen enough".
1726 * Now that we woke up, it's crucial if we're supposed to be
1727 * frozen that we freeze now before running anything substantial.
1731 spin_lock_irq(&sighand->siglock);
1733 * Every stopped thread goes here after wakeup. Check to see if
1734 * we should notify the parent, prepare_signal(SIGCONT) encodes
1735 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1737 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1738 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1739 ? CLD_CONTINUED : CLD_STOPPED;
1740 signal->flags &= ~SIGNAL_CLD_MASK;
1741 spin_unlock_irq(&sighand->siglock);
1743 read_lock(&tasklist_lock);
1744 do_notify_parent_cldstop(current->group_leader, why);
1745 read_unlock(&tasklist_lock);
1750 struct k_sigaction *ka;
1752 if (unlikely(signal->group_stop_count > 0) &&
1756 signr = dequeue_signal(current, ¤t->blocked, info);
1758 break; /* will return 0 */
1760 if (signr != SIGKILL) {
1761 signr = ptrace_signal(signr, info, regs, cookie);
1766 ka = &sighand->action[signr-1];
1767 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1769 if (ka->sa.sa_handler != SIG_DFL) {
1770 /* Run the handler. */
1773 if (ka->sa.sa_flags & SA_ONESHOT)
1774 ka->sa.sa_handler = SIG_DFL;
1776 break; /* will return non-zero "signr" value */
1780 * Now we are doing the default action for this signal.
1782 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1786 * Global init gets no signals it doesn't want.
1788 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1789 !signal_group_exit(signal))
1792 if (sig_kernel_stop(signr)) {
1794 * The default action is to stop all threads in
1795 * the thread group. The job control signals
1796 * do nothing in an orphaned pgrp, but SIGSTOP
1797 * always works. Note that siglock needs to be
1798 * dropped during the call to is_orphaned_pgrp()
1799 * because of lock ordering with tasklist_lock.
1800 * This allows an intervening SIGCONT to be posted.
1801 * We need to check for that and bail out if necessary.
1803 if (signr != SIGSTOP) {
1804 spin_unlock_irq(&sighand->siglock);
1806 /* signals can be posted during this window */
1808 if (is_current_pgrp_orphaned())
1811 spin_lock_irq(&sighand->siglock);
1814 if (likely(do_signal_stop(signr))) {
1815 /* It released the siglock. */
1820 * We didn't actually stop, due to a race
1821 * with SIGCONT or something like that.
1826 spin_unlock_irq(&sighand->siglock);
1829 * Anything else is fatal, maybe with a core dump.
1831 current->flags |= PF_SIGNALED;
1833 if (sig_kernel_coredump(signr)) {
1834 if (print_fatal_signals)
1835 print_fatal_signal(regs, signr);
1837 * If it was able to dump core, this kills all
1838 * other threads in the group and synchronizes with
1839 * their demise. If we lost the race with another
1840 * thread getting here, it set group_exit_code
1841 * first and our do_group_exit call below will use
1842 * that value and ignore the one we pass it.
1844 do_coredump((long)signr, signr, regs);
1848 * Death signals, no core dump.
1850 do_group_exit(signr);
1853 spin_unlock_irq(&sighand->siglock);
1857 void exit_signals(struct task_struct *tsk)
1860 struct task_struct *t;
1862 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1863 tsk->flags |= PF_EXITING;
1867 spin_lock_irq(&tsk->sighand->siglock);
1869 * From now this task is not visible for group-wide signals,
1870 * see wants_signal(), do_signal_stop().
1872 tsk->flags |= PF_EXITING;
1873 if (!signal_pending(tsk))
1876 /* It could be that __group_complete_signal() choose us to
1877 * notify about group-wide signal. Another thread should be
1878 * woken now to take the signal since we will not.
1880 for (t = tsk; (t = next_thread(t)) != tsk; )
1881 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1882 recalc_sigpending_and_wake(t);
1884 if (unlikely(tsk->signal->group_stop_count) &&
1885 !--tsk->signal->group_stop_count) {
1886 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1890 spin_unlock_irq(&tsk->sighand->siglock);
1892 if (unlikely(group_stop)) {
1893 read_lock(&tasklist_lock);
1894 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1895 read_unlock(&tasklist_lock);
1899 EXPORT_SYMBOL(recalc_sigpending);
1900 EXPORT_SYMBOL_GPL(dequeue_signal);
1901 EXPORT_SYMBOL(flush_signals);
1902 EXPORT_SYMBOL(force_sig);
1903 EXPORT_SYMBOL(send_sig);
1904 EXPORT_SYMBOL(send_sig_info);
1905 EXPORT_SYMBOL(sigprocmask);
1906 EXPORT_SYMBOL(block_all_signals);
1907 EXPORT_SYMBOL(unblock_all_signals);
1911 * System call entry points.
1914 asmlinkage long sys_restart_syscall(void)
1916 struct restart_block *restart = ¤t_thread_info()->restart_block;
1917 return restart->fn(restart);
1920 long do_no_restart_syscall(struct restart_block *param)
1926 * We don't need to get the kernel lock - this is all local to this
1927 * particular thread.. (and that's good, because this is _heavily_
1928 * used by various programs)
1932 * This is also useful for kernel threads that want to temporarily
1933 * (or permanently) block certain signals.
1935 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1936 * interface happily blocks "unblockable" signals like SIGKILL
1939 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1943 spin_lock_irq(¤t->sighand->siglock);
1945 *oldset = current->blocked;
1950 sigorsets(¤t->blocked, ¤t->blocked, set);
1953 signandsets(¤t->blocked, ¤t->blocked, set);
1956 current->blocked = *set;
1961 recalc_sigpending();
1962 spin_unlock_irq(¤t->sighand->siglock);
1968 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1970 int error = -EINVAL;
1971 sigset_t old_set, new_set;
1973 /* XXX: Don't preclude handling different sized sigset_t's. */
1974 if (sigsetsize != sizeof(sigset_t))
1979 if (copy_from_user(&new_set, set, sizeof(*set)))
1981 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1983 error = sigprocmask(how, &new_set, &old_set);
1989 spin_lock_irq(¤t->sighand->siglock);
1990 old_set = current->blocked;
1991 spin_unlock_irq(¤t->sighand->siglock);
1995 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2003 long do_sigpending(void __user *set, unsigned long sigsetsize)
2005 long error = -EINVAL;
2008 if (sigsetsize > sizeof(sigset_t))
2011 spin_lock_irq(¤t->sighand->siglock);
2012 sigorsets(&pending, ¤t->pending.signal,
2013 ¤t->signal->shared_pending.signal);
2014 spin_unlock_irq(¤t->sighand->siglock);
2016 /* Outside the lock because only this thread touches it. */
2017 sigandsets(&pending, ¤t->blocked, &pending);
2020 if (!copy_to_user(set, &pending, sigsetsize))
2028 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2030 return do_sigpending(set, sigsetsize);
2033 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2035 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2039 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2041 if (from->si_code < 0)
2042 return __copy_to_user(to, from, sizeof(siginfo_t))
2045 * If you change siginfo_t structure, please be sure
2046 * this code is fixed accordingly.
2047 * Please remember to update the signalfd_copyinfo() function
2048 * inside fs/signalfd.c too, in case siginfo_t changes.
2049 * It should never copy any pad contained in the structure
2050 * to avoid security leaks, but must copy the generic
2051 * 3 ints plus the relevant union member.
2053 err = __put_user(from->si_signo, &to->si_signo);
2054 err |= __put_user(from->si_errno, &to->si_errno);
2055 err |= __put_user((short)from->si_code, &to->si_code);
2056 switch (from->si_code & __SI_MASK) {
2058 err |= __put_user(from->si_pid, &to->si_pid);
2059 err |= __put_user(from->si_uid, &to->si_uid);
2062 err |= __put_user(from->si_tid, &to->si_tid);
2063 err |= __put_user(from->si_overrun, &to->si_overrun);
2064 err |= __put_user(from->si_ptr, &to->si_ptr);
2067 err |= __put_user(from->si_band, &to->si_band);
2068 err |= __put_user(from->si_fd, &to->si_fd);
2071 err |= __put_user(from->si_addr, &to->si_addr);
2072 #ifdef __ARCH_SI_TRAPNO
2073 err |= __put_user(from->si_trapno, &to->si_trapno);
2077 err |= __put_user(from->si_pid, &to->si_pid);
2078 err |= __put_user(from->si_uid, &to->si_uid);
2079 err |= __put_user(from->si_status, &to->si_status);
2080 err |= __put_user(from->si_utime, &to->si_utime);
2081 err |= __put_user(from->si_stime, &to->si_stime);
2083 case __SI_RT: /* This is not generated by the kernel as of now. */
2084 case __SI_MESGQ: /* But this is */
2085 err |= __put_user(from->si_pid, &to->si_pid);
2086 err |= __put_user(from->si_uid, &to->si_uid);
2087 err |= __put_user(from->si_ptr, &to->si_ptr);
2089 default: /* this is just in case for now ... */
2090 err |= __put_user(from->si_pid, &to->si_pid);
2091 err |= __put_user(from->si_uid, &to->si_uid);
2100 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2101 siginfo_t __user *uinfo,
2102 const struct timespec __user *uts,
2111 /* XXX: Don't preclude handling different sized sigset_t's. */
2112 if (sigsetsize != sizeof(sigset_t))
2115 if (copy_from_user(&these, uthese, sizeof(these)))
2119 * Invert the set of allowed signals to get those we
2122 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2126 if (copy_from_user(&ts, uts, sizeof(ts)))
2128 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2133 spin_lock_irq(¤t->sighand->siglock);
2134 sig = dequeue_signal(current, &these, &info);
2136 timeout = MAX_SCHEDULE_TIMEOUT;
2138 timeout = (timespec_to_jiffies(&ts)
2139 + (ts.tv_sec || ts.tv_nsec));
2142 /* None ready -- temporarily unblock those we're
2143 * interested while we are sleeping in so that we'll
2144 * be awakened when they arrive. */
2145 current->real_blocked = current->blocked;
2146 sigandsets(¤t->blocked, ¤t->blocked, &these);
2147 recalc_sigpending();
2148 spin_unlock_irq(¤t->sighand->siglock);
2150 timeout = schedule_timeout_interruptible(timeout);
2152 spin_lock_irq(¤t->sighand->siglock);
2153 sig = dequeue_signal(current, &these, &info);
2154 current->blocked = current->real_blocked;
2155 siginitset(¤t->real_blocked, 0);
2156 recalc_sigpending();
2159 spin_unlock_irq(¤t->sighand->siglock);
2164 if (copy_siginfo_to_user(uinfo, &info))
2177 sys_kill(pid_t pid, int sig)
2179 struct siginfo info;
2181 info.si_signo = sig;
2183 info.si_code = SI_USER;
2184 info.si_pid = task_tgid_vnr(current);
2185 info.si_uid = current->uid;
2187 return kill_something_info(sig, &info, pid);
2190 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2193 struct siginfo info;
2194 struct task_struct *p;
2195 unsigned long flags;
2198 info.si_signo = sig;
2200 info.si_code = SI_TKILL;
2201 info.si_pid = task_tgid_vnr(current);
2202 info.si_uid = current->uid;
2205 p = find_task_by_vpid(pid);
2206 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2207 error = check_kill_permission(sig, &info, p);
2209 * The null signal is a permissions and process existence
2210 * probe. No signal is actually delivered.
2212 * If lock_task_sighand() fails we pretend the task dies
2213 * after receiving the signal. The window is tiny, and the
2214 * signal is private anyway.
2216 if (!error && sig && lock_task_sighand(p, &flags)) {
2217 error = specific_send_sig_info(sig, &info, p);
2218 unlock_task_sighand(p, &flags);
2227 * sys_tgkill - send signal to one specific thread
2228 * @tgid: the thread group ID of the thread
2229 * @pid: the PID of the thread
2230 * @sig: signal to be sent
2232 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2233 * exists but it's not belonging to the target process anymore. This
2234 * method solves the problem of threads exiting and PIDs getting reused.
2236 asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig)
2238 /* This is only valid for single tasks */
2239 if (pid <= 0 || tgid <= 0)
2242 return do_tkill(tgid, pid, sig);
2246 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2249 sys_tkill(pid_t pid, int sig)
2251 /* This is only valid for single tasks */
2255 return do_tkill(0, pid, sig);
2259 sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo)
2263 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2266 /* Not even root can pretend to send signals from the kernel.
2267 Nor can they impersonate a kill(), which adds source info. */
2268 if (info.si_code >= 0)
2270 info.si_signo = sig;
2272 /* POSIX.1b doesn't mention process groups. */
2273 return kill_proc_info(sig, &info, pid);
2276 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2278 struct task_struct *t = current;
2279 struct k_sigaction *k;
2282 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2285 k = &t->sighand->action[sig-1];
2287 spin_lock_irq(¤t->sighand->siglock);
2292 sigdelsetmask(&act->sa.sa_mask,
2293 sigmask(SIGKILL) | sigmask(SIGSTOP));
2297 * "Setting a signal action to SIG_IGN for a signal that is
2298 * pending shall cause the pending signal to be discarded,
2299 * whether or not it is blocked."
2301 * "Setting a signal action to SIG_DFL for a signal that is
2302 * pending and whose default action is to ignore the signal
2303 * (for example, SIGCHLD), shall cause the pending signal to
2304 * be discarded, whether or not it is blocked"
2306 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2308 sigaddset(&mask, sig);
2309 rm_from_queue_full(&mask, &t->signal->shared_pending);
2311 rm_from_queue_full(&mask, &t->pending);
2313 } while (t != current);
2317 spin_unlock_irq(¤t->sighand->siglock);
2322 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2328 oss.ss_sp = (void __user *) current->sas_ss_sp;
2329 oss.ss_size = current->sas_ss_size;
2330 oss.ss_flags = sas_ss_flags(sp);
2339 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2340 || __get_user(ss_sp, &uss->ss_sp)
2341 || __get_user(ss_flags, &uss->ss_flags)
2342 || __get_user(ss_size, &uss->ss_size))
2346 if (on_sig_stack(sp))
2352 * Note - this code used to test ss_flags incorrectly
2353 * old code may have been written using ss_flags==0
2354 * to mean ss_flags==SS_ONSTACK (as this was the only
2355 * way that worked) - this fix preserves that older
2358 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2361 if (ss_flags == SS_DISABLE) {
2366 if (ss_size < MINSIGSTKSZ)
2370 current->sas_ss_sp = (unsigned long) ss_sp;
2371 current->sas_ss_size = ss_size;
2376 if (copy_to_user(uoss, &oss, sizeof(oss)))
2385 #ifdef __ARCH_WANT_SYS_SIGPENDING
2388 sys_sigpending(old_sigset_t __user *set)
2390 return do_sigpending(set, sizeof(*set));
2395 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2396 /* Some platforms have their own version with special arguments others
2397 support only sys_rt_sigprocmask. */
2400 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2403 old_sigset_t old_set, new_set;
2407 if (copy_from_user(&new_set, set, sizeof(*set)))
2409 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2411 spin_lock_irq(¤t->sighand->siglock);
2412 old_set = current->blocked.sig[0];
2420 sigaddsetmask(¤t->blocked, new_set);
2423 sigdelsetmask(¤t->blocked, new_set);
2426 current->blocked.sig[0] = new_set;
2430 recalc_sigpending();
2431 spin_unlock_irq(¤t->sighand->siglock);
2437 old_set = current->blocked.sig[0];
2440 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2447 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2449 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2451 sys_rt_sigaction(int sig,
2452 const struct sigaction __user *act,
2453 struct sigaction __user *oact,
2456 struct k_sigaction new_sa, old_sa;
2459 /* XXX: Don't preclude handling different sized sigset_t's. */
2460 if (sigsetsize != sizeof(sigset_t))
2464 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2468 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2471 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2477 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2479 #ifdef __ARCH_WANT_SYS_SGETMASK
2482 * For backwards compatibility. Functionality superseded by sigprocmask.
2488 return current->blocked.sig[0];
2492 sys_ssetmask(int newmask)
2496 spin_lock_irq(¤t->sighand->siglock);
2497 old = current->blocked.sig[0];
2499 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2501 recalc_sigpending();
2502 spin_unlock_irq(¤t->sighand->siglock);
2506 #endif /* __ARCH_WANT_SGETMASK */
2508 #ifdef __ARCH_WANT_SYS_SIGNAL
2510 * For backwards compatibility. Functionality superseded by sigaction.
2512 asmlinkage unsigned long
2513 sys_signal(int sig, __sighandler_t handler)
2515 struct k_sigaction new_sa, old_sa;
2518 new_sa.sa.sa_handler = handler;
2519 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2520 sigemptyset(&new_sa.sa.sa_mask);
2522 ret = do_sigaction(sig, &new_sa, &old_sa);
2524 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2526 #endif /* __ARCH_WANT_SYS_SIGNAL */
2528 #ifdef __ARCH_WANT_SYS_PAUSE
2533 current->state = TASK_INTERRUPTIBLE;
2535 return -ERESTARTNOHAND;
2540 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2541 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2545 /* XXX: Don't preclude handling different sized sigset_t's. */
2546 if (sigsetsize != sizeof(sigset_t))
2549 if (copy_from_user(&newset, unewset, sizeof(newset)))
2551 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2553 spin_lock_irq(¤t->sighand->siglock);
2554 current->saved_sigmask = current->blocked;
2555 current->blocked = newset;
2556 recalc_sigpending();
2557 spin_unlock_irq(¤t->sighand->siglock);
2559 current->state = TASK_INTERRUPTIBLE;
2561 set_restore_sigmask();
2562 return -ERESTARTNOHAND;
2564 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2566 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2571 void __init signals_init(void)
2573 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);