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;
42 static int __sig_ignored(struct task_struct *t, int sig)
46 /* Is it explicitly or implicitly ignored? */
48 handler = t->sighand->action[sig - 1].sa.sa_handler;
49 return handler == SIG_IGN ||
50 (handler == SIG_DFL && sig_kernel_ignore(sig));
53 static int sig_ignored(struct task_struct *t, int sig)
56 * Tracers always want to know about signals..
58 if (t->ptrace & PT_PTRACED)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
69 return __sig_ignored(t, sig);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
81 switch (_NSIG_WORDS) {
83 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
84 ready |= signal->sig[i] &~ blocked->sig[i];
87 case 4: ready = signal->sig[3] &~ blocked->sig[3];
88 ready |= signal->sig[2] &~ blocked->sig[2];
89 ready |= signal->sig[1] &~ blocked->sig[1];
90 ready |= signal->sig[0] &~ blocked->sig[0];
93 case 2: ready = signal->sig[1] &~ blocked->sig[1];
94 ready |= signal->sig[0] &~ blocked->sig[0];
97 case 1: ready = signal->sig[0] &~ blocked->sig[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct *t)
106 if (t->signal->group_stop_count > 0 ||
107 PENDING(&t->pending, &t->blocked) ||
108 PENDING(&t->signal->shared_pending, &t->blocked)) {
109 set_tsk_thread_flag(t, TIF_SIGPENDING);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct *t)
126 if (recalc_sigpending_tsk(t))
127 signal_wake_up(t, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current) && !freezing(current))
133 clear_thread_flag(TIF_SIGPENDING);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending *pending, sigset_t *mask)
141 unsigned long i, *s, *m, x;
144 s = pending->signal.sig;
146 switch (_NSIG_WORDS) {
148 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
149 if ((x = *s &~ *m) != 0) {
150 sig = ffz(~x) + i*_NSIG_BPW + 1;
155 case 2: if ((x = s[0] &~ m[0]) != 0)
157 else if ((x = s[1] &~ m[1]) != 0)
164 case 1: if ((x = *s &~ *m) != 0)
172 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
175 struct sigqueue *q = NULL;
176 struct user_struct *user;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user->sigpending);
185 if (override_rlimit ||
186 atomic_read(&user->sigpending) <=
187 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
188 q = kmem_cache_alloc(sigqueue_cachep, flags);
189 if (unlikely(q == NULL)) {
190 atomic_dec(&user->sigpending);
192 INIT_LIST_HEAD(&q->list);
194 q->user = get_uid(user);
199 static void __sigqueue_free(struct sigqueue *q)
201 if (q->flags & SIGQUEUE_PREALLOC)
203 atomic_dec(&q->user->sigpending);
205 kmem_cache_free(sigqueue_cachep, q);
208 void flush_sigqueue(struct sigpending *queue)
212 sigemptyset(&queue->signal);
213 while (!list_empty(&queue->list)) {
214 q = list_entry(queue->list.next, struct sigqueue , list);
215 list_del_init(&q->list);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct *t)
227 spin_lock_irqsave(&t->sighand->siglock, flags);
228 clear_tsk_thread_flag(t, TIF_SIGPENDING);
229 flush_sigqueue(&t->pending);
230 flush_sigqueue(&t->signal->shared_pending);
231 spin_unlock_irqrestore(&t->sighand->siglock, flags);
234 void ignore_signals(struct task_struct *t)
238 for (i = 0; i < _NSIG; ++i)
239 t->sighand->action[i].sa.sa_handler = SIG_IGN;
245 * Flush all handlers for a task.
249 flush_signal_handlers(struct task_struct *t, int force_default)
252 struct k_sigaction *ka = &t->sighand->action[0];
253 for (i = _NSIG ; i != 0 ; i--) {
254 if (force_default || ka->sa.sa_handler != SIG_IGN)
255 ka->sa.sa_handler = SIG_DFL;
257 sigemptyset(&ka->sa.sa_mask);
262 int unhandled_signal(struct task_struct *tsk, int sig)
264 if (is_global_init(tsk))
266 if (tsk->ptrace & PT_PTRACED)
268 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
269 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
273 /* Notify the system that a driver wants to block all signals for this
274 * process, and wants to be notified if any signals at all were to be
275 * sent/acted upon. If the notifier routine returns non-zero, then the
276 * signal will be acted upon after all. If the notifier routine returns 0,
277 * then then signal will be blocked. Only one block per process is
278 * allowed. priv is a pointer to private data that the notifier routine
279 * can use to determine if the signal should be blocked or not. */
282 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
286 spin_lock_irqsave(¤t->sighand->siglock, flags);
287 current->notifier_mask = mask;
288 current->notifier_data = priv;
289 current->notifier = notifier;
290 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
293 /* Notify the system that blocking has ended. */
296 unblock_all_signals(void)
300 spin_lock_irqsave(¤t->sighand->siglock, flags);
301 current->notifier = NULL;
302 current->notifier_data = NULL;
304 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
307 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
309 struct sigqueue *q, *first = NULL;
310 int still_pending = 0;
312 if (unlikely(!sigismember(&list->signal, sig)))
316 * Collect the siginfo appropriate to this signal. Check if
317 * there is another siginfo for the same signal.
319 list_for_each_entry(q, &list->list, list) {
320 if (q->info.si_signo == sig) {
329 list_del_init(&first->list);
330 copy_siginfo(info, &first->info);
331 __sigqueue_free(first);
333 sigdelset(&list->signal, sig);
336 /* Ok, it wasn't in the queue. This must be
337 a fast-pathed signal or we must have been
338 out of queue space. So zero out the info.
340 sigdelset(&list->signal, sig);
341 info->si_signo = sig;
350 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
353 int sig = next_signal(pending, mask);
356 if (current->notifier) {
357 if (sigismember(current->notifier_mask, sig)) {
358 if (!(current->notifier)(current->notifier_data)) {
359 clear_thread_flag(TIF_SIGPENDING);
365 if (!collect_signal(sig, pending, info))
373 * Dequeue a signal and return the element to the caller, which is
374 * expected to free it.
376 * All callers have to hold the siglock.
378 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
382 /* We only dequeue private signals from ourselves, we don't let
383 * signalfd steal them
385 signr = __dequeue_signal(&tsk->pending, mask, info);
387 signr = __dequeue_signal(&tsk->signal->shared_pending,
392 * itimers are process shared and we restart periodic
393 * itimers in the signal delivery path to prevent DoS
394 * attacks in the high resolution timer case. This is
395 * compliant with the old way of self restarting
396 * itimers, as the SIGALRM is a legacy signal and only
397 * queued once. Changing the restart behaviour to
398 * restart the timer in the signal dequeue path is
399 * reducing the timer noise on heavy loaded !highres
402 if (unlikely(signr == SIGALRM)) {
403 struct hrtimer *tmr = &tsk->signal->real_timer;
405 if (!hrtimer_is_queued(tmr) &&
406 tsk->signal->it_real_incr.tv64 != 0) {
407 hrtimer_forward(tmr, tmr->base->get_time(),
408 tsk->signal->it_real_incr);
409 hrtimer_restart(tmr);
418 if (unlikely(sig_kernel_stop(signr))) {
420 * Set a marker that we have dequeued a stop signal. Our
421 * caller might release the siglock and then the pending
422 * stop signal it is about to process is no longer in the
423 * pending bitmasks, but must still be cleared by a SIGCONT
424 * (and overruled by a SIGKILL). So those cases clear this
425 * shared flag after we've set it. Note that this flag may
426 * remain set after the signal we return is ignored or
427 * handled. That doesn't matter because its only purpose
428 * is to alert stop-signal processing code when another
429 * processor has come along and cleared the flag.
431 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
432 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
434 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
436 * Release the siglock to ensure proper locking order
437 * of timer locks outside of siglocks. Note, we leave
438 * irqs disabled here, since the posix-timers code is
439 * about to disable them again anyway.
441 spin_unlock(&tsk->sighand->siglock);
442 do_schedule_next_timer(info);
443 spin_lock(&tsk->sighand->siglock);
449 * Tell a process that it has a new active signal..
451 * NOTE! we rely on the previous spin_lock to
452 * lock interrupts for us! We can only be called with
453 * "siglock" held, and the local interrupt must
454 * have been disabled when that got acquired!
456 * No need to set need_resched since signal event passing
457 * goes through ->blocked
459 void signal_wake_up(struct task_struct *t, int resume)
463 set_tsk_thread_flag(t, TIF_SIGPENDING);
466 * For SIGKILL, we want to wake it up in the stopped/traced/killable
467 * case. We don't check t->state here because there is a race with it
468 * executing another processor and just now entering stopped state.
469 * By using wake_up_state, we ensure the process will wake up and
470 * handle its death signal.
472 mask = TASK_INTERRUPTIBLE;
474 mask |= TASK_WAKEKILL;
475 if (!wake_up_state(t, mask))
480 * Remove signals in mask from the pending set and queue.
481 * Returns 1 if any signals were found.
483 * All callers must be holding the siglock.
485 * This version takes a sigset mask and looks at all signals,
486 * not just those in the first mask word.
488 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
490 struct sigqueue *q, *n;
493 sigandsets(&m, mask, &s->signal);
494 if (sigisemptyset(&m))
497 signandsets(&s->signal, &s->signal, mask);
498 list_for_each_entry_safe(q, n, &s->list, list) {
499 if (sigismember(mask, q->info.si_signo)) {
500 list_del_init(&q->list);
507 * Remove signals in mask from the pending set and queue.
508 * Returns 1 if any signals were found.
510 * All callers must be holding the siglock.
512 static int rm_from_queue(unsigned long mask, struct sigpending *s)
514 struct sigqueue *q, *n;
516 if (!sigtestsetmask(&s->signal, mask))
519 sigdelsetmask(&s->signal, mask);
520 list_for_each_entry_safe(q, n, &s->list, list) {
521 if (q->info.si_signo < SIGRTMIN &&
522 (mask & sigmask(q->info.si_signo))) {
523 list_del_init(&q->list);
531 * Bad permissions for sending the signal
533 static int check_kill_permission(int sig, struct siginfo *info,
534 struct task_struct *t)
537 if (!valid_signal(sig))
540 if (info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info))) {
541 error = audit_signal_info(sig, t); /* Let audit system see the signal */
545 if (((sig != SIGCONT) ||
546 (task_session_nr(current) != task_session_nr(t)))
547 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
548 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
549 && !capable(CAP_KILL))
553 return security_task_kill(t, info, sig, 0);
557 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
560 * Handle magic process-wide effects of stop/continue signals.
561 * Unlike the signal actions, these happen immediately at signal-generation
562 * time regardless of blocking, ignoring, or handling. This does the
563 * actual continuing for SIGCONT, but not the actual stopping for stop
564 * signals. The process stop is done as a signal action for SIG_DFL.
566 static void handle_stop_signal(int sig, struct task_struct *p)
568 struct task_struct *t;
570 if (p->signal->flags & SIGNAL_GROUP_EXIT)
572 * The process is in the middle of dying already.
576 if (sig_kernel_stop(sig)) {
578 * This is a stop signal. Remove SIGCONT from all queues.
580 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
583 rm_from_queue(sigmask(SIGCONT), &t->pending);
586 } else if (sig == SIGCONT) {
588 * Remove all stop signals from all queues,
589 * and wake all threads.
591 if (unlikely(p->signal->group_stop_count > 0)) {
593 * There was a group stop in progress. We'll
594 * pretend it finished before we got here. We are
595 * obliged to report it to the parent: if the
596 * SIGSTOP happened "after" this SIGCONT, then it
597 * would have cleared this pending SIGCONT. If it
598 * happened "before" this SIGCONT, then the parent
599 * got the SIGCHLD about the stop finishing before
600 * the continue happened. We do the notification
601 * now, and it's as if the stop had finished and
602 * the SIGCHLD was pending on entry to this kill.
604 p->signal->group_stop_count = 0;
605 p->signal->flags = SIGNAL_STOP_CONTINUED;
606 spin_unlock(&p->sighand->siglock);
607 do_notify_parent_cldstop(p, CLD_STOPPED);
608 spin_lock(&p->sighand->siglock);
610 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
614 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
617 * If there is a handler for SIGCONT, we must make
618 * sure that no thread returns to user mode before
619 * we post the signal, in case it was the only
620 * thread eligible to run the signal handler--then
621 * it must not do anything between resuming and
622 * running the handler. With the TIF_SIGPENDING
623 * flag set, the thread will pause and acquire the
624 * siglock that we hold now and until we've queued
625 * the pending signal.
627 * Wake up the stopped thread _after_ setting
630 state = __TASK_STOPPED;
631 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
632 set_tsk_thread_flag(t, TIF_SIGPENDING);
633 state |= TASK_INTERRUPTIBLE;
635 wake_up_state(t, state);
640 if (p->signal->flags & SIGNAL_STOP_STOPPED) {
642 * We were in fact stopped, and are now continued.
643 * Notify the parent with CLD_CONTINUED.
645 p->signal->flags = SIGNAL_STOP_CONTINUED;
646 p->signal->group_exit_code = 0;
647 spin_unlock(&p->sighand->siglock);
648 do_notify_parent_cldstop(p, CLD_CONTINUED);
649 spin_lock(&p->sighand->siglock);
652 * We are not stopped, but there could be a stop
653 * signal in the middle of being processed after
654 * being removed from the queue. Clear that too.
656 p->signal->flags = 0;
658 } else if (sig == SIGKILL) {
660 * Make sure that any pending stop signal already dequeued
661 * is undone by the wakeup for SIGKILL.
663 p->signal->flags = 0;
667 static inline int legacy_queue(struct sigpending *signals, int sig)
669 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
672 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
673 struct sigpending *signals)
675 struct sigqueue * q = NULL;
678 * Short-circuit ignored signals and support queuing
679 * exactly one non-rt signal, so that we can get more
680 * detailed information about the cause of the signal.
682 if (sig_ignored(t, sig) || legacy_queue(signals, sig))
686 * Deliver the signal to listening signalfds. This must be called
687 * with the sighand lock held.
689 signalfd_notify(t, sig);
692 * fast-pathed signals for kernel-internal things like SIGSTOP
695 if (info == SEND_SIG_FORCED)
698 /* Real-time signals must be queued if sent by sigqueue, or
699 some other real-time mechanism. It is implementation
700 defined whether kill() does so. We attempt to do so, on
701 the principle of least surprise, but since kill is not
702 allowed to fail with EAGAIN when low on memory we just
703 make sure at least one signal gets delivered and don't
704 pass on the info struct. */
706 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
707 (is_si_special(info) ||
708 info->si_code >= 0)));
710 list_add_tail(&q->list, &signals->list);
711 switch ((unsigned long) info) {
712 case (unsigned long) SEND_SIG_NOINFO:
713 q->info.si_signo = sig;
714 q->info.si_errno = 0;
715 q->info.si_code = SI_USER;
716 q->info.si_pid = task_pid_vnr(current);
717 q->info.si_uid = current->uid;
719 case (unsigned long) SEND_SIG_PRIV:
720 q->info.si_signo = sig;
721 q->info.si_errno = 0;
722 q->info.si_code = SI_KERNEL;
727 copy_siginfo(&q->info, info);
730 } else if (!is_si_special(info)) {
731 if (sig >= SIGRTMIN && info->si_code != SI_USER)
733 * Queue overflow, abort. We may abort if the signal was rt
734 * and sent by user using something other than kill().
740 sigaddset(&signals->signal, sig);
744 int print_fatal_signals;
746 static void print_fatal_signal(struct pt_regs *regs, int signr)
748 printk("%s/%d: potentially unexpected fatal signal %d.\n",
749 current->comm, task_pid_nr(current), signr);
751 #if defined(__i386__) && !defined(__arch_um__)
752 printk("code at %08lx: ", regs->ip);
755 for (i = 0; i < 16; i++) {
758 __get_user(insn, (unsigned char *)(regs->ip + i));
759 printk("%02x ", insn);
767 static int __init setup_print_fatal_signals(char *str)
769 get_option (&str, &print_fatal_signals);
774 __setup("print-fatal-signals=", setup_print_fatal_signals);
777 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
781 BUG_ON(!irqs_disabled());
782 assert_spin_locked(&t->sighand->siglock);
784 ret = send_signal(sig, info, t, &t->pending);
788 if (!sigismember(&t->blocked, sig))
789 signal_wake_up(t, sig == SIGKILL);
794 * Force a signal that the process can't ignore: if necessary
795 * we unblock the signal and change any SIG_IGN to SIG_DFL.
797 * Note: If we unblock the signal, we always reset it to SIG_DFL,
798 * since we do not want to have a signal handler that was blocked
799 * be invoked when user space had explicitly blocked it.
801 * We don't want to have recursive SIGSEGV's etc, for example.
804 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
806 unsigned long int flags;
807 int ret, blocked, ignored;
808 struct k_sigaction *action;
810 spin_lock_irqsave(&t->sighand->siglock, flags);
811 action = &t->sighand->action[sig-1];
812 ignored = action->sa.sa_handler == SIG_IGN;
813 blocked = sigismember(&t->blocked, sig);
814 if (blocked || ignored) {
815 action->sa.sa_handler = SIG_DFL;
817 sigdelset(&t->blocked, sig);
818 recalc_sigpending_and_wake(t);
821 ret = specific_send_sig_info(sig, info, t);
822 spin_unlock_irqrestore(&t->sighand->siglock, flags);
828 force_sig_specific(int sig, struct task_struct *t)
830 force_sig_info(sig, SEND_SIG_FORCED, t);
834 * Test if P wants to take SIG. After we've checked all threads with this,
835 * it's equivalent to finding no threads not blocking SIG. Any threads not
836 * blocking SIG were ruled out because they are not running and already
837 * have pending signals. Such threads will dequeue from the shared queue
838 * as soon as they're available, so putting the signal on the shared queue
839 * will be equivalent to sending it to one such thread.
841 static inline int wants_signal(int sig, struct task_struct *p)
843 if (sigismember(&p->blocked, sig))
845 if (p->flags & PF_EXITING)
849 if (task_is_stopped_or_traced(p))
851 return task_curr(p) || !signal_pending(p);
855 __group_complete_signal(int sig, struct task_struct *p)
857 struct task_struct *t;
860 * Now find a thread we can wake up to take the signal off the queue.
862 * If the main thread wants the signal, it gets first crack.
863 * Probably the least surprising to the average bear.
865 if (wants_signal(sig, p))
867 else if (thread_group_empty(p))
869 * There is just one thread and it does not need to be woken.
870 * It will dequeue unblocked signals before it runs again.
875 * Otherwise try to find a suitable thread.
877 t = p->signal->curr_target;
879 /* restart balancing at this thread */
880 t = p->signal->curr_target = p;
882 while (!wants_signal(sig, t)) {
884 if (t == p->signal->curr_target)
886 * No thread needs to be woken.
887 * Any eligible threads will see
888 * the signal in the queue soon.
892 p->signal->curr_target = t;
896 * Found a killable thread. If the signal will be fatal,
897 * then start taking the whole group down immediately.
899 if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
900 !sigismember(&t->real_blocked, sig) &&
901 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
903 * This signal will be fatal to the whole group.
905 if (!sig_kernel_coredump(sig)) {
907 * Start a group exit and wake everybody up.
908 * This way we don't have other threads
909 * running and doing things after a slower
910 * thread has the fatal signal pending.
912 p->signal->flags = SIGNAL_GROUP_EXIT;
913 p->signal->group_exit_code = sig;
914 p->signal->group_stop_count = 0;
917 sigaddset(&t->pending.signal, SIGKILL);
918 signal_wake_up(t, 1);
919 } while_each_thread(p, t);
925 * The signal is already in the shared-pending queue.
926 * Tell the chosen thread to wake up and dequeue it.
928 signal_wake_up(t, sig == SIGKILL);
933 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
937 assert_spin_locked(&p->sighand->siglock);
938 handle_stop_signal(sig, p);
941 * Put this signal on the shared-pending queue, or fail with EAGAIN.
942 * We always use the shared queue for process-wide signals,
943 * to avoid several races.
945 ret = send_signal(sig, info, p, &p->signal->shared_pending);
949 __group_complete_signal(sig, p);
954 * Nuke all other threads in the group.
956 void zap_other_threads(struct task_struct *p)
958 struct task_struct *t;
960 p->signal->group_stop_count = 0;
962 for (t = next_thread(p); t != p; t = next_thread(t)) {
964 * Don't bother with already dead threads
969 /* SIGKILL will be handled before any pending SIGSTOP */
970 sigaddset(&t->pending.signal, SIGKILL);
971 signal_wake_up(t, 1);
975 int __fatal_signal_pending(struct task_struct *tsk)
977 return sigismember(&tsk->pending.signal, SIGKILL);
979 EXPORT_SYMBOL(__fatal_signal_pending);
981 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
983 struct sighand_struct *sighand;
987 sighand = rcu_dereference(tsk->sighand);
988 if (unlikely(sighand == NULL))
991 spin_lock_irqsave(&sighand->siglock, *flags);
992 if (likely(sighand == tsk->sighand))
994 spin_unlock_irqrestore(&sighand->siglock, *flags);
1001 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1003 unsigned long flags;
1006 ret = check_kill_permission(sig, info, p);
1010 if (lock_task_sighand(p, &flags)) {
1011 ret = __group_send_sig_info(sig, info, p);
1012 unlock_task_sighand(p, &flags);
1020 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1021 * control characters do (^C, ^Z etc)
1024 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1026 struct task_struct *p = NULL;
1027 int retval, success;
1031 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1032 int err = group_send_sig_info(sig, info, p);
1035 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1036 return success ? 0 : retval;
1039 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1042 struct task_struct *p;
1045 if (unlikely(sig_needs_tasklist(sig)))
1046 read_lock(&tasklist_lock);
1049 p = pid_task(pid, PIDTYPE_PID);
1051 error = group_send_sig_info(sig, info, p);
1052 if (unlikely(error == -ESRCH))
1054 * The task was unhashed in between, try again.
1055 * If it is dead, pid_task() will return NULL,
1056 * if we race with de_thread() it will find the
1062 if (unlikely(sig_needs_tasklist(sig)))
1063 read_unlock(&tasklist_lock);
1069 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1073 error = kill_pid_info(sig, info, find_vpid(pid));
1078 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1079 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1080 uid_t uid, uid_t euid, u32 secid)
1083 struct task_struct *p;
1085 if (!valid_signal(sig))
1088 read_lock(&tasklist_lock);
1089 p = pid_task(pid, PIDTYPE_PID);
1094 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1095 && (euid != p->suid) && (euid != p->uid)
1096 && (uid != p->suid) && (uid != p->uid)) {
1100 ret = security_task_kill(p, info, sig, secid);
1103 if (sig && p->sighand) {
1104 unsigned long flags;
1105 spin_lock_irqsave(&p->sighand->siglock, flags);
1106 ret = __group_send_sig_info(sig, info, p);
1107 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1110 read_unlock(&tasklist_lock);
1113 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1116 * kill_something_info() interprets pid in interesting ways just like kill(2).
1118 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1119 * is probably wrong. Should make it like BSD or SYSV.
1122 static int kill_something_info(int sig, struct siginfo *info, int pid)
1128 ret = kill_pid_info(sig, info, find_vpid(pid));
1133 read_lock(&tasklist_lock);
1135 ret = __kill_pgrp_info(sig, info,
1136 pid ? find_vpid(-pid) : task_pgrp(current));
1138 int retval = 0, count = 0;
1139 struct task_struct * p;
1141 for_each_process(p) {
1142 if (p->pid > 1 && !same_thread_group(p, current)) {
1143 int err = group_send_sig_info(sig, info, p);
1149 ret = count ? retval : -ESRCH;
1151 read_unlock(&tasklist_lock);
1157 * These are for backward compatibility with the rest of the kernel source.
1161 * These two are the most common entry points. They send a signal
1162 * just to the specific thread.
1165 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1168 unsigned long flags;
1171 * Make sure legacy kernel users don't send in bad values
1172 * (normal paths check this in check_kill_permission).
1174 if (!valid_signal(sig))
1178 * We need the tasklist lock even for the specific
1179 * thread case (when we don't need to follow the group
1180 * lists) in order to avoid races with "p->sighand"
1181 * going away or changing from under us.
1183 read_lock(&tasklist_lock);
1184 spin_lock_irqsave(&p->sighand->siglock, flags);
1185 ret = specific_send_sig_info(sig, info, p);
1186 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1187 read_unlock(&tasklist_lock);
1191 #define __si_special(priv) \
1192 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1195 send_sig(int sig, struct task_struct *p, int priv)
1197 return send_sig_info(sig, __si_special(priv), p);
1201 force_sig(int sig, struct task_struct *p)
1203 force_sig_info(sig, SEND_SIG_PRIV, p);
1207 * When things go south during signal handling, we
1208 * will force a SIGSEGV. And if the signal that caused
1209 * the problem was already a SIGSEGV, we'll want to
1210 * make sure we don't even try to deliver the signal..
1213 force_sigsegv(int sig, struct task_struct *p)
1215 if (sig == SIGSEGV) {
1216 unsigned long flags;
1217 spin_lock_irqsave(&p->sighand->siglock, flags);
1218 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1219 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1221 force_sig(SIGSEGV, p);
1225 int kill_pgrp(struct pid *pid, int sig, int priv)
1229 read_lock(&tasklist_lock);
1230 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1231 read_unlock(&tasklist_lock);
1235 EXPORT_SYMBOL(kill_pgrp);
1237 int kill_pid(struct pid *pid, int sig, int priv)
1239 return kill_pid_info(sig, __si_special(priv), pid);
1241 EXPORT_SYMBOL(kill_pid);
1244 kill_proc(pid_t pid, int sig, int priv)
1249 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1255 * These functions support sending signals using preallocated sigqueue
1256 * structures. This is needed "because realtime applications cannot
1257 * afford to lose notifications of asynchronous events, like timer
1258 * expirations or I/O completions". In the case of Posix Timers
1259 * we allocate the sigqueue structure from the timer_create. If this
1260 * allocation fails we are able to report the failure to the application
1261 * with an EAGAIN error.
1264 struct sigqueue *sigqueue_alloc(void)
1268 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1269 q->flags |= SIGQUEUE_PREALLOC;
1273 void sigqueue_free(struct sigqueue *q)
1275 unsigned long flags;
1276 spinlock_t *lock = ¤t->sighand->siglock;
1278 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1280 * If the signal is still pending remove it from the
1281 * pending queue. We must hold ->siglock while testing
1282 * q->list to serialize with collect_signal().
1284 spin_lock_irqsave(lock, flags);
1285 if (!list_empty(&q->list))
1286 list_del_init(&q->list);
1287 spin_unlock_irqrestore(lock, flags);
1289 q->flags &= ~SIGQUEUE_PREALLOC;
1293 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1295 unsigned long flags;
1298 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1301 * The rcu based delayed sighand destroy makes it possible to
1302 * run this without tasklist lock held. The task struct itself
1303 * cannot go away as create_timer did get_task_struct().
1305 * We return -1, when the task is marked exiting, so
1306 * posix_timer_event can redirect it to the group leader
1310 if (!likely(lock_task_sighand(p, &flags))) {
1315 if (unlikely(!list_empty(&q->list))) {
1317 * If an SI_TIMER entry is already queue just increment
1318 * the overrun count.
1320 BUG_ON(q->info.si_code != SI_TIMER);
1321 q->info.si_overrun++;
1324 /* Short-circuit ignored signals. */
1325 if (sig_ignored(p, sig)) {
1330 * Deliver the signal to listening signalfds. This must be called
1331 * with the sighand lock held.
1333 signalfd_notify(p, sig);
1335 list_add_tail(&q->list, &p->pending.list);
1336 sigaddset(&p->pending.signal, sig);
1337 if (!sigismember(&p->blocked, sig))
1338 signal_wake_up(p, sig == SIGKILL);
1341 unlock_task_sighand(p, &flags);
1349 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1351 unsigned long flags;
1354 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1356 read_lock(&tasklist_lock);
1357 /* Since it_lock is held, p->sighand cannot be NULL. */
1358 spin_lock_irqsave(&p->sighand->siglock, flags);
1359 handle_stop_signal(sig, p);
1361 /* Short-circuit ignored signals. */
1362 if (sig_ignored(p, sig)) {
1367 if (unlikely(!list_empty(&q->list))) {
1369 * If an SI_TIMER entry is already queue just increment
1370 * the overrun count. Other uses should not try to
1371 * send the signal multiple times.
1373 BUG_ON(q->info.si_code != SI_TIMER);
1374 q->info.si_overrun++;
1378 * Deliver the signal to listening signalfds. This must be called
1379 * with the sighand lock held.
1381 signalfd_notify(p, sig);
1384 * Put this signal on the shared-pending queue.
1385 * We always use the shared queue for process-wide signals,
1386 * to avoid several races.
1388 list_add_tail(&q->list, &p->signal->shared_pending.list);
1389 sigaddset(&p->signal->shared_pending.signal, sig);
1391 __group_complete_signal(sig, p);
1393 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1394 read_unlock(&tasklist_lock);
1399 * Wake up any threads in the parent blocked in wait* syscalls.
1401 static inline void __wake_up_parent(struct task_struct *p,
1402 struct task_struct *parent)
1404 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1408 * Let a parent know about the death of a child.
1409 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1412 void do_notify_parent(struct task_struct *tsk, int sig)
1414 struct siginfo info;
1415 unsigned long flags;
1416 struct sighand_struct *psig;
1420 /* do_notify_parent_cldstop should have been called instead. */
1421 BUG_ON(task_is_stopped_or_traced(tsk));
1423 BUG_ON(!tsk->ptrace &&
1424 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1426 info.si_signo = sig;
1429 * we are under tasklist_lock here so our parent is tied to
1430 * us and cannot exit and release its namespace.
1432 * the only it can is to switch its nsproxy with sys_unshare,
1433 * bu uncharing pid namespaces is not allowed, so we'll always
1434 * see relevant namespace
1436 * write_lock() currently calls preempt_disable() which is the
1437 * same as rcu_read_lock(), but according to Oleg, this is not
1438 * correct to rely on this
1441 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1444 info.si_uid = tsk->uid;
1446 /* FIXME: find out whether or not this is supposed to be c*time. */
1447 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1448 tsk->signal->utime));
1449 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1450 tsk->signal->stime));
1452 info.si_status = tsk->exit_code & 0x7f;
1453 if (tsk->exit_code & 0x80)
1454 info.si_code = CLD_DUMPED;
1455 else if (tsk->exit_code & 0x7f)
1456 info.si_code = CLD_KILLED;
1458 info.si_code = CLD_EXITED;
1459 info.si_status = tsk->exit_code >> 8;
1462 psig = tsk->parent->sighand;
1463 spin_lock_irqsave(&psig->siglock, flags);
1464 if (!tsk->ptrace && sig == SIGCHLD &&
1465 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1466 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1468 * We are exiting and our parent doesn't care. POSIX.1
1469 * defines special semantics for setting SIGCHLD to SIG_IGN
1470 * or setting the SA_NOCLDWAIT flag: we should be reaped
1471 * automatically and not left for our parent's wait4 call.
1472 * Rather than having the parent do it as a magic kind of
1473 * signal handler, we just set this to tell do_exit that we
1474 * can be cleaned up without becoming a zombie. Note that
1475 * we still call __wake_up_parent in this case, because a
1476 * blocked sys_wait4 might now return -ECHILD.
1478 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1479 * is implementation-defined: we do (if you don't want
1480 * it, just use SIG_IGN instead).
1482 tsk->exit_signal = -1;
1483 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1486 if (valid_signal(sig) && sig > 0)
1487 __group_send_sig_info(sig, &info, tsk->parent);
1488 __wake_up_parent(tsk, tsk->parent);
1489 spin_unlock_irqrestore(&psig->siglock, flags);
1492 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1494 struct siginfo info;
1495 unsigned long flags;
1496 struct task_struct *parent;
1497 struct sighand_struct *sighand;
1499 if (tsk->ptrace & PT_PTRACED)
1500 parent = tsk->parent;
1502 tsk = tsk->group_leader;
1503 parent = tsk->real_parent;
1506 info.si_signo = SIGCHLD;
1509 * see comment in do_notify_parent() abot the following 3 lines
1512 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1515 info.si_uid = tsk->uid;
1517 /* FIXME: find out whether or not this is supposed to be c*time. */
1518 info.si_utime = cputime_to_jiffies(tsk->utime);
1519 info.si_stime = cputime_to_jiffies(tsk->stime);
1524 info.si_status = SIGCONT;
1527 info.si_status = tsk->signal->group_exit_code & 0x7f;
1530 info.si_status = tsk->exit_code & 0x7f;
1536 sighand = parent->sighand;
1537 spin_lock_irqsave(&sighand->siglock, flags);
1538 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1539 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1540 __group_send_sig_info(SIGCHLD, &info, parent);
1542 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1544 __wake_up_parent(tsk, parent);
1545 spin_unlock_irqrestore(&sighand->siglock, flags);
1548 static inline int may_ptrace_stop(void)
1550 if (!likely(current->ptrace & PT_PTRACED))
1553 * Are we in the middle of do_coredump?
1554 * If so and our tracer is also part of the coredump stopping
1555 * is a deadlock situation, and pointless because our tracer
1556 * is dead so don't allow us to stop.
1557 * If SIGKILL was already sent before the caller unlocked
1558 * ->siglock we must see ->core_waiters != 0. Otherwise it
1559 * is safe to enter schedule().
1561 if (unlikely(current->mm->core_waiters) &&
1562 unlikely(current->mm == current->parent->mm))
1569 * Return nonzero if there is a SIGKILL that should be waking us up.
1570 * Called with the siglock held.
1572 static int sigkill_pending(struct task_struct *tsk)
1574 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1575 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1576 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1580 * This must be called with current->sighand->siglock held.
1582 * This should be the path for all ptrace stops.
1583 * We always set current->last_siginfo while stopped here.
1584 * That makes it a way to test a stopped process for
1585 * being ptrace-stopped vs being job-control-stopped.
1587 * If we actually decide not to stop at all because the tracer
1588 * is gone, we keep current->exit_code unless clear_code.
1590 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1594 if (arch_ptrace_stop_needed(exit_code, info)) {
1596 * The arch code has something special to do before a
1597 * ptrace stop. This is allowed to block, e.g. for faults
1598 * on user stack pages. We can't keep the siglock while
1599 * calling arch_ptrace_stop, so we must release it now.
1600 * To preserve proper semantics, we must do this before
1601 * any signal bookkeeping like checking group_stop_count.
1602 * Meanwhile, a SIGKILL could come in before we retake the
1603 * siglock. That must prevent us from sleeping in TASK_TRACED.
1604 * So after regaining the lock, we must check for SIGKILL.
1606 spin_unlock_irq(¤t->sighand->siglock);
1607 arch_ptrace_stop(exit_code, info);
1608 spin_lock_irq(¤t->sighand->siglock);
1609 killed = sigkill_pending(current);
1613 * If there is a group stop in progress,
1614 * we must participate in the bookkeeping.
1616 if (current->signal->group_stop_count > 0)
1617 --current->signal->group_stop_count;
1619 current->last_siginfo = info;
1620 current->exit_code = exit_code;
1622 /* Let the debugger run. */
1623 __set_current_state(TASK_TRACED);
1624 spin_unlock_irq(¤t->sighand->siglock);
1625 read_lock(&tasklist_lock);
1626 if (!unlikely(killed) && may_ptrace_stop()) {
1627 do_notify_parent_cldstop(current, CLD_TRAPPED);
1628 read_unlock(&tasklist_lock);
1632 * By the time we got the lock, our tracer went away.
1633 * Don't drop the lock yet, another tracer may come.
1635 __set_current_state(TASK_RUNNING);
1637 current->exit_code = 0;
1638 read_unlock(&tasklist_lock);
1642 * While in TASK_TRACED, we were considered "frozen enough".
1643 * Now that we woke up, it's crucial if we're supposed to be
1644 * frozen that we freeze now before running anything substantial.
1649 * We are back. Now reacquire the siglock before touching
1650 * last_siginfo, so that we are sure to have synchronized with
1651 * any signal-sending on another CPU that wants to examine it.
1653 spin_lock_irq(¤t->sighand->siglock);
1654 current->last_siginfo = NULL;
1657 * Queued signals ignored us while we were stopped for tracing.
1658 * So check for any that we should take before resuming user mode.
1659 * This sets TIF_SIGPENDING, but never clears it.
1661 recalc_sigpending_tsk(current);
1664 void ptrace_notify(int exit_code)
1668 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1670 memset(&info, 0, sizeof info);
1671 info.si_signo = SIGTRAP;
1672 info.si_code = exit_code;
1673 info.si_pid = task_pid_vnr(current);
1674 info.si_uid = current->uid;
1676 /* Let the debugger run. */
1677 spin_lock_irq(¤t->sighand->siglock);
1678 ptrace_stop(exit_code, 1, &info);
1679 spin_unlock_irq(¤t->sighand->siglock);
1683 finish_stop(int stop_count)
1686 * If there are no other threads in the group, or if there is
1687 * a group stop in progress and we are the last to stop,
1688 * report to the parent. When ptraced, every thread reports itself.
1690 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1691 read_lock(&tasklist_lock);
1692 do_notify_parent_cldstop(current, CLD_STOPPED);
1693 read_unlock(&tasklist_lock);
1698 } while (try_to_freeze());
1700 * Now we don't run again until continued.
1702 current->exit_code = 0;
1706 * This performs the stopping for SIGSTOP and other stop signals.
1707 * We have to stop all threads in the thread group.
1708 * Returns nonzero if we've actually stopped and released the siglock.
1709 * Returns zero if we didn't stop and still hold the siglock.
1711 static int do_signal_stop(int signr)
1713 struct signal_struct *sig = current->signal;
1716 if (sig->group_stop_count > 0) {
1718 * There is a group stop in progress. We don't need to
1719 * start another one.
1721 stop_count = --sig->group_stop_count;
1723 struct task_struct *t;
1725 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1726 unlikely(signal_group_exit(sig)))
1729 * There is no group stop already in progress.
1730 * We must initiate one now.
1732 sig->group_exit_code = signr;
1735 for (t = next_thread(current); t != current; t = next_thread(t))
1737 * Setting state to TASK_STOPPED for a group
1738 * stop is always done with the siglock held,
1739 * so this check has no races.
1741 if (!(t->flags & PF_EXITING) &&
1742 !task_is_stopped_or_traced(t)) {
1744 signal_wake_up(t, 0);
1746 sig->group_stop_count = stop_count;
1749 if (stop_count == 0)
1750 sig->flags = SIGNAL_STOP_STOPPED;
1751 current->exit_code = sig->group_exit_code;
1752 __set_current_state(TASK_STOPPED);
1754 spin_unlock_irq(¤t->sighand->siglock);
1755 finish_stop(stop_count);
1759 static int ptrace_signal(int signr, siginfo_t *info,
1760 struct pt_regs *regs, void *cookie)
1762 if (!(current->ptrace & PT_PTRACED))
1765 ptrace_signal_deliver(regs, cookie);
1767 /* Let the debugger run. */
1768 ptrace_stop(signr, 0, info);
1770 /* We're back. Did the debugger cancel the sig? */
1771 signr = current->exit_code;
1775 current->exit_code = 0;
1777 /* Update the siginfo structure if the signal has
1778 changed. If the debugger wanted something
1779 specific in the siginfo structure then it should
1780 have updated *info via PTRACE_SETSIGINFO. */
1781 if (signr != info->si_signo) {
1782 info->si_signo = signr;
1784 info->si_code = SI_USER;
1785 info->si_pid = task_pid_vnr(current->parent);
1786 info->si_uid = current->parent->uid;
1789 /* If the (new) signal is now blocked, requeue it. */
1790 if (sigismember(¤t->blocked, signr)) {
1791 specific_send_sig_info(signr, info, current);
1798 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1799 struct pt_regs *regs, void *cookie)
1801 sigset_t *mask = ¤t->blocked;
1806 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1807 * While in TASK_STOPPED, we were considered "frozen enough".
1808 * Now that we woke up, it's crucial if we're supposed to be
1809 * frozen that we freeze now before running anything substantial.
1813 spin_lock_irq(¤t->sighand->siglock);
1815 struct k_sigaction *ka;
1817 if (unlikely(current->signal->group_stop_count > 0) &&
1821 signr = dequeue_signal(current, mask, info);
1824 break; /* will return 0 */
1826 if (signr != SIGKILL) {
1827 signr = ptrace_signal(signr, info, regs, cookie);
1832 ka = ¤t->sighand->action[signr-1];
1833 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1835 if (ka->sa.sa_handler != SIG_DFL) {
1836 /* Run the handler. */
1839 if (ka->sa.sa_flags & SA_ONESHOT)
1840 ka->sa.sa_handler = SIG_DFL;
1842 break; /* will return non-zero "signr" value */
1846 * Now we are doing the default action for this signal.
1848 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1852 * Global init gets no signals it doesn't want.
1854 if (is_global_init(current))
1857 if (sig_kernel_stop(signr)) {
1859 * The default action is to stop all threads in
1860 * the thread group. The job control signals
1861 * do nothing in an orphaned pgrp, but SIGSTOP
1862 * always works. Note that siglock needs to be
1863 * dropped during the call to is_orphaned_pgrp()
1864 * because of lock ordering with tasklist_lock.
1865 * This allows an intervening SIGCONT to be posted.
1866 * We need to check for that and bail out if necessary.
1868 if (signr != SIGSTOP) {
1869 spin_unlock_irq(¤t->sighand->siglock);
1871 /* signals can be posted during this window */
1873 if (is_current_pgrp_orphaned())
1876 spin_lock_irq(¤t->sighand->siglock);
1879 if (likely(do_signal_stop(signr))) {
1880 /* It released the siglock. */
1885 * We didn't actually stop, due to a race
1886 * with SIGCONT or something like that.
1891 spin_unlock_irq(¤t->sighand->siglock);
1894 * Anything else is fatal, maybe with a core dump.
1896 current->flags |= PF_SIGNALED;
1897 if ((signr != SIGKILL) && print_fatal_signals)
1898 print_fatal_signal(regs, signr);
1899 if (sig_kernel_coredump(signr)) {
1901 * If it was able to dump core, this kills all
1902 * other threads in the group and synchronizes with
1903 * their demise. If we lost the race with another
1904 * thread getting here, it set group_exit_code
1905 * first and our do_group_exit call below will use
1906 * that value and ignore the one we pass it.
1908 do_coredump((long)signr, signr, regs);
1912 * Death signals, no core dump.
1914 do_group_exit(signr);
1917 spin_unlock_irq(¤t->sighand->siglock);
1921 void exit_signals(struct task_struct *tsk)
1924 struct task_struct *t;
1926 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1927 tsk->flags |= PF_EXITING;
1931 spin_lock_irq(&tsk->sighand->siglock);
1933 * From now this task is not visible for group-wide signals,
1934 * see wants_signal(), do_signal_stop().
1936 tsk->flags |= PF_EXITING;
1937 if (!signal_pending(tsk))
1940 /* It could be that __group_complete_signal() choose us to
1941 * notify about group-wide signal. Another thread should be
1942 * woken now to take the signal since we will not.
1944 for (t = tsk; (t = next_thread(t)) != tsk; )
1945 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1946 recalc_sigpending_and_wake(t);
1948 if (unlikely(tsk->signal->group_stop_count) &&
1949 !--tsk->signal->group_stop_count) {
1950 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1954 spin_unlock_irq(&tsk->sighand->siglock);
1956 if (unlikely(group_stop)) {
1957 read_lock(&tasklist_lock);
1958 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1959 read_unlock(&tasklist_lock);
1963 EXPORT_SYMBOL(recalc_sigpending);
1964 EXPORT_SYMBOL_GPL(dequeue_signal);
1965 EXPORT_SYMBOL(flush_signals);
1966 EXPORT_SYMBOL(force_sig);
1967 EXPORT_SYMBOL(kill_proc);
1968 EXPORT_SYMBOL(ptrace_notify);
1969 EXPORT_SYMBOL(send_sig);
1970 EXPORT_SYMBOL(send_sig_info);
1971 EXPORT_SYMBOL(sigprocmask);
1972 EXPORT_SYMBOL(block_all_signals);
1973 EXPORT_SYMBOL(unblock_all_signals);
1977 * System call entry points.
1980 asmlinkage long sys_restart_syscall(void)
1982 struct restart_block *restart = ¤t_thread_info()->restart_block;
1983 return restart->fn(restart);
1986 long do_no_restart_syscall(struct restart_block *param)
1992 * We don't need to get the kernel lock - this is all local to this
1993 * particular thread.. (and that's good, because this is _heavily_
1994 * used by various programs)
1998 * This is also useful for kernel threads that want to temporarily
1999 * (or permanently) block certain signals.
2001 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2002 * interface happily blocks "unblockable" signals like SIGKILL
2005 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2009 spin_lock_irq(¤t->sighand->siglock);
2011 *oldset = current->blocked;
2016 sigorsets(¤t->blocked, ¤t->blocked, set);
2019 signandsets(¤t->blocked, ¤t->blocked, set);
2022 current->blocked = *set;
2027 recalc_sigpending();
2028 spin_unlock_irq(¤t->sighand->siglock);
2034 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2036 int error = -EINVAL;
2037 sigset_t old_set, new_set;
2039 /* XXX: Don't preclude handling different sized sigset_t's. */
2040 if (sigsetsize != sizeof(sigset_t))
2045 if (copy_from_user(&new_set, set, sizeof(*set)))
2047 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2049 error = sigprocmask(how, &new_set, &old_set);
2055 spin_lock_irq(¤t->sighand->siglock);
2056 old_set = current->blocked;
2057 spin_unlock_irq(¤t->sighand->siglock);
2061 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2069 long do_sigpending(void __user *set, unsigned long sigsetsize)
2071 long error = -EINVAL;
2074 if (sigsetsize > sizeof(sigset_t))
2077 spin_lock_irq(¤t->sighand->siglock);
2078 sigorsets(&pending, ¤t->pending.signal,
2079 ¤t->signal->shared_pending.signal);
2080 spin_unlock_irq(¤t->sighand->siglock);
2082 /* Outside the lock because only this thread touches it. */
2083 sigandsets(&pending, ¤t->blocked, &pending);
2086 if (!copy_to_user(set, &pending, sigsetsize))
2094 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2096 return do_sigpending(set, sigsetsize);
2099 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2101 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2105 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2107 if (from->si_code < 0)
2108 return __copy_to_user(to, from, sizeof(siginfo_t))
2111 * If you change siginfo_t structure, please be sure
2112 * this code is fixed accordingly.
2113 * Please remember to update the signalfd_copyinfo() function
2114 * inside fs/signalfd.c too, in case siginfo_t changes.
2115 * It should never copy any pad contained in the structure
2116 * to avoid security leaks, but must copy the generic
2117 * 3 ints plus the relevant union member.
2119 err = __put_user(from->si_signo, &to->si_signo);
2120 err |= __put_user(from->si_errno, &to->si_errno);
2121 err |= __put_user((short)from->si_code, &to->si_code);
2122 switch (from->si_code & __SI_MASK) {
2124 err |= __put_user(from->si_pid, &to->si_pid);
2125 err |= __put_user(from->si_uid, &to->si_uid);
2128 err |= __put_user(from->si_tid, &to->si_tid);
2129 err |= __put_user(from->si_overrun, &to->si_overrun);
2130 err |= __put_user(from->si_ptr, &to->si_ptr);
2133 err |= __put_user(from->si_band, &to->si_band);
2134 err |= __put_user(from->si_fd, &to->si_fd);
2137 err |= __put_user(from->si_addr, &to->si_addr);
2138 #ifdef __ARCH_SI_TRAPNO
2139 err |= __put_user(from->si_trapno, &to->si_trapno);
2143 err |= __put_user(from->si_pid, &to->si_pid);
2144 err |= __put_user(from->si_uid, &to->si_uid);
2145 err |= __put_user(from->si_status, &to->si_status);
2146 err |= __put_user(from->si_utime, &to->si_utime);
2147 err |= __put_user(from->si_stime, &to->si_stime);
2149 case __SI_RT: /* This is not generated by the kernel as of now. */
2150 case __SI_MESGQ: /* But this is */
2151 err |= __put_user(from->si_pid, &to->si_pid);
2152 err |= __put_user(from->si_uid, &to->si_uid);
2153 err |= __put_user(from->si_ptr, &to->si_ptr);
2155 default: /* this is just in case for now ... */
2156 err |= __put_user(from->si_pid, &to->si_pid);
2157 err |= __put_user(from->si_uid, &to->si_uid);
2166 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2167 siginfo_t __user *uinfo,
2168 const struct timespec __user *uts,
2177 /* XXX: Don't preclude handling different sized sigset_t's. */
2178 if (sigsetsize != sizeof(sigset_t))
2181 if (copy_from_user(&these, uthese, sizeof(these)))
2185 * Invert the set of allowed signals to get those we
2188 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2192 if (copy_from_user(&ts, uts, sizeof(ts)))
2194 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2199 spin_lock_irq(¤t->sighand->siglock);
2200 sig = dequeue_signal(current, &these, &info);
2202 timeout = MAX_SCHEDULE_TIMEOUT;
2204 timeout = (timespec_to_jiffies(&ts)
2205 + (ts.tv_sec || ts.tv_nsec));
2208 /* None ready -- temporarily unblock those we're
2209 * interested while we are sleeping in so that we'll
2210 * be awakened when they arrive. */
2211 current->real_blocked = current->blocked;
2212 sigandsets(¤t->blocked, ¤t->blocked, &these);
2213 recalc_sigpending();
2214 spin_unlock_irq(¤t->sighand->siglock);
2216 timeout = schedule_timeout_interruptible(timeout);
2218 spin_lock_irq(¤t->sighand->siglock);
2219 sig = dequeue_signal(current, &these, &info);
2220 current->blocked = current->real_blocked;
2221 siginitset(¤t->real_blocked, 0);
2222 recalc_sigpending();
2225 spin_unlock_irq(¤t->sighand->siglock);
2230 if (copy_siginfo_to_user(uinfo, &info))
2243 sys_kill(int pid, int sig)
2245 struct siginfo info;
2247 info.si_signo = sig;
2249 info.si_code = SI_USER;
2250 info.si_pid = task_tgid_vnr(current);
2251 info.si_uid = current->uid;
2253 return kill_something_info(sig, &info, pid);
2256 static int do_tkill(int tgid, int pid, int sig)
2259 struct siginfo info;
2260 struct task_struct *p;
2263 info.si_signo = sig;
2265 info.si_code = SI_TKILL;
2266 info.si_pid = task_tgid_vnr(current);
2267 info.si_uid = current->uid;
2269 read_lock(&tasklist_lock);
2270 p = find_task_by_vpid(pid);
2271 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2272 error = check_kill_permission(sig, &info, p);
2274 * The null signal is a permissions and process existence
2275 * probe. No signal is actually delivered.
2277 if (!error && sig && p->sighand) {
2278 spin_lock_irq(&p->sighand->siglock);
2279 handle_stop_signal(sig, p);
2280 error = specific_send_sig_info(sig, &info, p);
2281 spin_unlock_irq(&p->sighand->siglock);
2284 read_unlock(&tasklist_lock);
2290 * sys_tgkill - send signal to one specific thread
2291 * @tgid: the thread group ID of the thread
2292 * @pid: the PID of the thread
2293 * @sig: signal to be sent
2295 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2296 * exists but it's not belonging to the target process anymore. This
2297 * method solves the problem of threads exiting and PIDs getting reused.
2299 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2301 /* This is only valid for single tasks */
2302 if (pid <= 0 || tgid <= 0)
2305 return do_tkill(tgid, pid, sig);
2309 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2312 sys_tkill(int pid, int sig)
2314 /* This is only valid for single tasks */
2318 return do_tkill(0, pid, sig);
2322 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2326 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2329 /* Not even root can pretend to send signals from the kernel.
2330 Nor can they impersonate a kill(), which adds source info. */
2331 if (info.si_code >= 0)
2333 info.si_signo = sig;
2335 /* POSIX.1b doesn't mention process groups. */
2336 return kill_proc_info(sig, &info, pid);
2339 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2341 struct task_struct *t = current;
2342 struct k_sigaction *k;
2345 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2348 k = &t->sighand->action[sig-1];
2350 spin_lock_irq(¤t->sighand->siglock);
2355 sigdelsetmask(&act->sa.sa_mask,
2356 sigmask(SIGKILL) | sigmask(SIGSTOP));
2360 * "Setting a signal action to SIG_IGN for a signal that is
2361 * pending shall cause the pending signal to be discarded,
2362 * whether or not it is blocked."
2364 * "Setting a signal action to SIG_DFL for a signal that is
2365 * pending and whose default action is to ignore the signal
2366 * (for example, SIGCHLD), shall cause the pending signal to
2367 * be discarded, whether or not it is blocked"
2369 if (__sig_ignored(t, sig)) {
2371 sigaddset(&mask, sig);
2372 rm_from_queue_full(&mask, &t->signal->shared_pending);
2374 rm_from_queue_full(&mask, &t->pending);
2376 } while (t != current);
2380 spin_unlock_irq(¤t->sighand->siglock);
2385 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2391 oss.ss_sp = (void __user *) current->sas_ss_sp;
2392 oss.ss_size = current->sas_ss_size;
2393 oss.ss_flags = sas_ss_flags(sp);
2402 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2403 || __get_user(ss_sp, &uss->ss_sp)
2404 || __get_user(ss_flags, &uss->ss_flags)
2405 || __get_user(ss_size, &uss->ss_size))
2409 if (on_sig_stack(sp))
2415 * Note - this code used to test ss_flags incorrectly
2416 * old code may have been written using ss_flags==0
2417 * to mean ss_flags==SS_ONSTACK (as this was the only
2418 * way that worked) - this fix preserves that older
2421 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2424 if (ss_flags == SS_DISABLE) {
2429 if (ss_size < MINSIGSTKSZ)
2433 current->sas_ss_sp = (unsigned long) ss_sp;
2434 current->sas_ss_size = ss_size;
2439 if (copy_to_user(uoss, &oss, sizeof(oss)))
2448 #ifdef __ARCH_WANT_SYS_SIGPENDING
2451 sys_sigpending(old_sigset_t __user *set)
2453 return do_sigpending(set, sizeof(*set));
2458 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2459 /* Some platforms have their own version with special arguments others
2460 support only sys_rt_sigprocmask. */
2463 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2466 old_sigset_t old_set, new_set;
2470 if (copy_from_user(&new_set, set, sizeof(*set)))
2472 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2474 spin_lock_irq(¤t->sighand->siglock);
2475 old_set = current->blocked.sig[0];
2483 sigaddsetmask(¤t->blocked, new_set);
2486 sigdelsetmask(¤t->blocked, new_set);
2489 current->blocked.sig[0] = new_set;
2493 recalc_sigpending();
2494 spin_unlock_irq(¤t->sighand->siglock);
2500 old_set = current->blocked.sig[0];
2503 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2510 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2512 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2514 sys_rt_sigaction(int sig,
2515 const struct sigaction __user *act,
2516 struct sigaction __user *oact,
2519 struct k_sigaction new_sa, old_sa;
2522 /* XXX: Don't preclude handling different sized sigset_t's. */
2523 if (sigsetsize != sizeof(sigset_t))
2527 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2531 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2534 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2540 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2542 #ifdef __ARCH_WANT_SYS_SGETMASK
2545 * For backwards compatibility. Functionality superseded by sigprocmask.
2551 return current->blocked.sig[0];
2555 sys_ssetmask(int newmask)
2559 spin_lock_irq(¤t->sighand->siglock);
2560 old = current->blocked.sig[0];
2562 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2564 recalc_sigpending();
2565 spin_unlock_irq(¤t->sighand->siglock);
2569 #endif /* __ARCH_WANT_SGETMASK */
2571 #ifdef __ARCH_WANT_SYS_SIGNAL
2573 * For backwards compatibility. Functionality superseded by sigaction.
2575 asmlinkage unsigned long
2576 sys_signal(int sig, __sighandler_t handler)
2578 struct k_sigaction new_sa, old_sa;
2581 new_sa.sa.sa_handler = handler;
2582 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2583 sigemptyset(&new_sa.sa.sa_mask);
2585 ret = do_sigaction(sig, &new_sa, &old_sa);
2587 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2589 #endif /* __ARCH_WANT_SYS_SIGNAL */
2591 #ifdef __ARCH_WANT_SYS_PAUSE
2596 current->state = TASK_INTERRUPTIBLE;
2598 return -ERESTARTNOHAND;
2603 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2604 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2608 /* XXX: Don't preclude handling different sized sigset_t's. */
2609 if (sigsetsize != sizeof(sigset_t))
2612 if (copy_from_user(&newset, unewset, sizeof(newset)))
2614 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2616 spin_lock_irq(¤t->sighand->siglock);
2617 current->saved_sigmask = current->blocked;
2618 current->blocked = newset;
2619 recalc_sigpending();
2620 spin_unlock_irq(¤t->sighand->siglock);
2622 current->state = TASK_INTERRUPTIBLE;
2624 set_thread_flag(TIF_RESTORE_SIGMASK);
2625 return -ERESTARTNOHAND;
2627 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2629 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2634 void __init signals_init(void)
2636 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);