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)
538 if (!valid_signal(sig))
541 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
544 error = audit_signal_info(sig, t); /* Let audit system see the signal */
548 if (((sig != SIGCONT) || (task_session_nr(current) != task_session_nr(t)))
549 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
550 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
551 && !capable(CAP_KILL))
554 return security_task_kill(t, info, sig, 0);
558 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
561 * Handle magic process-wide effects of stop/continue signals.
562 * Unlike the signal actions, these happen immediately at signal-generation
563 * time regardless of blocking, ignoring, or handling. This does the
564 * actual continuing for SIGCONT, but not the actual stopping for stop
565 * signals. The process stop is done as a signal action for SIG_DFL.
567 static void handle_stop_signal(int sig, struct task_struct *p)
569 struct signal_struct *signal = p->signal;
570 struct task_struct *t;
572 if (signal->flags & SIGNAL_GROUP_EXIT)
574 * The process is in the middle of dying already.
578 if (sig_kernel_stop(sig)) {
580 * This is a stop signal. Remove SIGCONT from all queues.
582 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
585 rm_from_queue(sigmask(SIGCONT), &t->pending);
586 } while_each_thread(p, t);
587 } else if (sig == SIGCONT) {
590 * Remove all stop signals from all queues,
591 * and wake all threads.
593 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
597 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
599 * If there is a handler for SIGCONT, we must make
600 * sure that no thread returns to user mode before
601 * we post the signal, in case it was the only
602 * thread eligible to run the signal handler--then
603 * it must not do anything between resuming and
604 * running the handler. With the TIF_SIGPENDING
605 * flag set, the thread will pause and acquire the
606 * siglock that we hold now and until we've queued
607 * the pending signal.
609 * Wake up the stopped thread _after_ setting
612 state = __TASK_STOPPED;
613 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
614 set_tsk_thread_flag(t, TIF_SIGPENDING);
615 state |= TASK_INTERRUPTIBLE;
617 wake_up_state(t, state);
618 } while_each_thread(p, t);
621 * Notify the parent with CLD_CONTINUED if we were stopped.
623 * If we were in the middle of a group stop, we pretend it
624 * was already finished, and then continued. Since SIGCHLD
625 * doesn't queue we report only CLD_STOPPED, as if the next
626 * CLD_CONTINUED was dropped.
629 if (signal->flags & SIGNAL_STOP_STOPPED)
630 why |= SIGNAL_CLD_CONTINUED;
631 else if (signal->group_stop_count)
632 why |= SIGNAL_CLD_STOPPED;
635 signal->flags = why | SIGNAL_STOP_CONTINUED;
636 signal->group_stop_count = 0;
637 signal->group_exit_code = 0;
640 * We are not stopped, but there could be a stop
641 * signal in the middle of being processed after
642 * being removed from the queue. Clear that too.
644 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
646 } else if (sig == SIGKILL) {
648 * Make sure that any pending stop signal already dequeued
649 * is undone by the wakeup for SIGKILL.
651 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
656 * Test if P wants to take SIG. After we've checked all threads with this,
657 * it's equivalent to finding no threads not blocking SIG. Any threads not
658 * blocking SIG were ruled out because they are not running and already
659 * have pending signals. Such threads will dequeue from the shared queue
660 * as soon as they're available, so putting the signal on the shared queue
661 * will be equivalent to sending it to one such thread.
663 static inline int wants_signal(int sig, struct task_struct *p)
665 if (sigismember(&p->blocked, sig))
667 if (p->flags & PF_EXITING)
671 if (task_is_stopped_or_traced(p))
673 return task_curr(p) || !signal_pending(p);
677 __group_complete_signal(int sig, struct task_struct *p)
679 struct signal_struct *signal = p->signal;
680 struct task_struct *t;
683 * Now find a thread we can wake up to take the signal off the queue.
685 * If the main thread wants the signal, it gets first crack.
686 * Probably the least surprising to the average bear.
688 if (wants_signal(sig, p))
690 else if (thread_group_empty(p))
692 * There is just one thread and it does not need to be woken.
693 * It will dequeue unblocked signals before it runs again.
698 * Otherwise try to find a suitable thread.
700 t = signal->curr_target;
701 while (!wants_signal(sig, t)) {
703 if (t == signal->curr_target)
705 * No thread needs to be woken.
706 * Any eligible threads will see
707 * the signal in the queue soon.
711 signal->curr_target = t;
715 * Found a killable thread. If the signal will be fatal,
716 * then start taking the whole group down immediately.
718 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
719 !sigismember(&t->real_blocked, sig) &&
720 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
722 * This signal will be fatal to the whole group.
724 if (!sig_kernel_coredump(sig)) {
726 * Start a group exit and wake everybody up.
727 * This way we don't have other threads
728 * running and doing things after a slower
729 * thread has the fatal signal pending.
731 signal->flags = SIGNAL_GROUP_EXIT;
732 signal->group_exit_code = sig;
733 signal->group_stop_count = 0;
736 sigaddset(&t->pending.signal, SIGKILL);
737 signal_wake_up(t, 1);
738 } while_each_thread(p, t);
744 * The signal is already in the shared-pending queue.
745 * Tell the chosen thread to wake up and dequeue it.
747 signal_wake_up(t, sig == SIGKILL);
751 static inline int legacy_queue(struct sigpending *signals, int sig)
753 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
756 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
759 struct sigpending *pending;
762 assert_spin_locked(&t->sighand->siglock);
763 handle_stop_signal(sig, t);
765 pending = group ? &t->signal->shared_pending : &t->pending;
767 * Short-circuit ignored signals and support queuing
768 * exactly one non-rt signal, so that we can get more
769 * detailed information about the cause of the signal.
771 if (sig_ignored(t, sig) || legacy_queue(pending, sig))
775 * Deliver the signal to listening signalfds. This must be called
776 * with the sighand lock held.
778 signalfd_notify(t, sig);
781 * fast-pathed signals for kernel-internal things like SIGSTOP
784 if (info == SEND_SIG_FORCED)
787 /* Real-time signals must be queued if sent by sigqueue, or
788 some other real-time mechanism. It is implementation
789 defined whether kill() does so. We attempt to do so, on
790 the principle of least surprise, but since kill is not
791 allowed to fail with EAGAIN when low on memory we just
792 make sure at least one signal gets delivered and don't
793 pass on the info struct. */
795 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
796 (is_si_special(info) ||
797 info->si_code >= 0)));
799 list_add_tail(&q->list, &pending->list);
800 switch ((unsigned long) info) {
801 case (unsigned long) SEND_SIG_NOINFO:
802 q->info.si_signo = sig;
803 q->info.si_errno = 0;
804 q->info.si_code = SI_USER;
805 q->info.si_pid = task_pid_vnr(current);
806 q->info.si_uid = current->uid;
808 case (unsigned long) SEND_SIG_PRIV:
809 q->info.si_signo = sig;
810 q->info.si_errno = 0;
811 q->info.si_code = SI_KERNEL;
816 copy_siginfo(&q->info, info);
819 } else if (!is_si_special(info)) {
820 if (sig >= SIGRTMIN && info->si_code != SI_USER)
822 * Queue overflow, abort. We may abort if the signal was rt
823 * and sent by user using something other than kill().
829 sigaddset(&pending->signal, sig);
833 int print_fatal_signals;
835 static void print_fatal_signal(struct pt_regs *regs, int signr)
837 printk("%s/%d: potentially unexpected fatal signal %d.\n",
838 current->comm, task_pid_nr(current), signr);
840 #if defined(__i386__) && !defined(__arch_um__)
841 printk("code at %08lx: ", regs->ip);
844 for (i = 0; i < 16; i++) {
847 __get_user(insn, (unsigned char *)(regs->ip + i));
848 printk("%02x ", insn);
856 static int __init setup_print_fatal_signals(char *str)
858 get_option (&str, &print_fatal_signals);
863 __setup("print-fatal-signals=", setup_print_fatal_signals);
866 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
870 ret = send_signal(sig, info, t, 0);
874 if (!sigismember(&t->blocked, sig))
875 signal_wake_up(t, sig == SIGKILL);
880 * Force a signal that the process can't ignore: if necessary
881 * we unblock the signal and change any SIG_IGN to SIG_DFL.
883 * Note: If we unblock the signal, we always reset it to SIG_DFL,
884 * since we do not want to have a signal handler that was blocked
885 * be invoked when user space had explicitly blocked it.
887 * We don't want to have recursive SIGSEGV's etc, for example.
890 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
892 unsigned long int flags;
893 int ret, blocked, ignored;
894 struct k_sigaction *action;
896 spin_lock_irqsave(&t->sighand->siglock, flags);
897 action = &t->sighand->action[sig-1];
898 ignored = action->sa.sa_handler == SIG_IGN;
899 blocked = sigismember(&t->blocked, sig);
900 if (blocked || ignored) {
901 action->sa.sa_handler = SIG_DFL;
903 sigdelset(&t->blocked, sig);
904 recalc_sigpending_and_wake(t);
907 ret = specific_send_sig_info(sig, info, t);
908 spin_unlock_irqrestore(&t->sighand->siglock, flags);
914 force_sig_specific(int sig, struct task_struct *t)
916 force_sig_info(sig, SEND_SIG_FORCED, t);
920 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
925 * Put this signal on the shared-pending queue, or fail with EAGAIN.
926 * We always use the shared queue for process-wide signals,
927 * to avoid several races.
929 ret = send_signal(sig, info, p, 1);
933 __group_complete_signal(sig, p);
938 * Nuke all other threads in the group.
940 void zap_other_threads(struct task_struct *p)
942 struct task_struct *t;
944 p->signal->group_stop_count = 0;
946 for (t = next_thread(p); t != p; t = next_thread(t)) {
948 * Don't bother with already dead threads
953 /* SIGKILL will be handled before any pending SIGSTOP */
954 sigaddset(&t->pending.signal, SIGKILL);
955 signal_wake_up(t, 1);
959 int __fatal_signal_pending(struct task_struct *tsk)
961 return sigismember(&tsk->pending.signal, SIGKILL);
963 EXPORT_SYMBOL(__fatal_signal_pending);
965 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
967 struct sighand_struct *sighand;
971 sighand = rcu_dereference(tsk->sighand);
972 if (unlikely(sighand == NULL))
975 spin_lock_irqsave(&sighand->siglock, *flags);
976 if (likely(sighand == tsk->sighand))
978 spin_unlock_irqrestore(&sighand->siglock, *flags);
985 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
990 ret = check_kill_permission(sig, info, p);
994 if (lock_task_sighand(p, &flags)) {
995 ret = __group_send_sig_info(sig, info, p);
996 unlock_task_sighand(p, &flags);
1004 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1005 * control characters do (^C, ^Z etc)
1008 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1010 struct task_struct *p = NULL;
1011 int retval, success;
1015 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1016 int err = group_send_sig_info(sig, info, p);
1019 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1020 return success ? 0 : retval;
1023 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1026 struct task_struct *p;
1030 p = pid_task(pid, PIDTYPE_PID);
1032 error = group_send_sig_info(sig, info, p);
1033 if (unlikely(error == -ESRCH))
1035 * The task was unhashed in between, try again.
1036 * If it is dead, pid_task() will return NULL,
1037 * if we race with de_thread() it will find the
1048 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1052 error = kill_pid_info(sig, info, find_vpid(pid));
1057 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1058 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1059 uid_t uid, uid_t euid, u32 secid)
1062 struct task_struct *p;
1064 if (!valid_signal(sig))
1067 read_lock(&tasklist_lock);
1068 p = pid_task(pid, PIDTYPE_PID);
1073 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1074 && (euid != p->suid) && (euid != p->uid)
1075 && (uid != p->suid) && (uid != p->uid)) {
1079 ret = security_task_kill(p, info, sig, secid);
1082 if (sig && p->sighand) {
1083 unsigned long flags;
1084 spin_lock_irqsave(&p->sighand->siglock, flags);
1085 ret = __group_send_sig_info(sig, info, p);
1086 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1089 read_unlock(&tasklist_lock);
1092 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1095 * kill_something_info() interprets pid in interesting ways just like kill(2).
1097 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1098 * is probably wrong. Should make it like BSD or SYSV.
1101 static int kill_something_info(int sig, struct siginfo *info, int pid)
1107 ret = kill_pid_info(sig, info, find_vpid(pid));
1112 read_lock(&tasklist_lock);
1114 ret = __kill_pgrp_info(sig, info,
1115 pid ? find_vpid(-pid) : task_pgrp(current));
1117 int retval = 0, count = 0;
1118 struct task_struct * p;
1120 for_each_process(p) {
1121 if (p->pid > 1 && !same_thread_group(p, current)) {
1122 int err = group_send_sig_info(sig, info, p);
1128 ret = count ? retval : -ESRCH;
1130 read_unlock(&tasklist_lock);
1136 * These are for backward compatibility with the rest of the kernel source.
1140 * The caller must ensure the task can't exit.
1143 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1146 unsigned long flags;
1149 * Make sure legacy kernel users don't send in bad values
1150 * (normal paths check this in check_kill_permission).
1152 if (!valid_signal(sig))
1155 spin_lock_irqsave(&p->sighand->siglock, flags);
1156 ret = specific_send_sig_info(sig, info, p);
1157 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1161 #define __si_special(priv) \
1162 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1165 send_sig(int sig, struct task_struct *p, int priv)
1167 return send_sig_info(sig, __si_special(priv), p);
1171 force_sig(int sig, struct task_struct *p)
1173 force_sig_info(sig, SEND_SIG_PRIV, p);
1177 * When things go south during signal handling, we
1178 * will force a SIGSEGV. And if the signal that caused
1179 * the problem was already a SIGSEGV, we'll want to
1180 * make sure we don't even try to deliver the signal..
1183 force_sigsegv(int sig, struct task_struct *p)
1185 if (sig == SIGSEGV) {
1186 unsigned long flags;
1187 spin_lock_irqsave(&p->sighand->siglock, flags);
1188 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1189 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1191 force_sig(SIGSEGV, p);
1195 int kill_pgrp(struct pid *pid, int sig, int priv)
1199 read_lock(&tasklist_lock);
1200 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1201 read_unlock(&tasklist_lock);
1205 EXPORT_SYMBOL(kill_pgrp);
1207 int kill_pid(struct pid *pid, int sig, int priv)
1209 return kill_pid_info(sig, __si_special(priv), pid);
1211 EXPORT_SYMBOL(kill_pid);
1214 kill_proc(pid_t pid, int sig, int priv)
1219 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1225 * These functions support sending signals using preallocated sigqueue
1226 * structures. This is needed "because realtime applications cannot
1227 * afford to lose notifications of asynchronous events, like timer
1228 * expirations or I/O completions". In the case of Posix Timers
1229 * we allocate the sigqueue structure from the timer_create. If this
1230 * allocation fails we are able to report the failure to the application
1231 * with an EAGAIN error.
1234 struct sigqueue *sigqueue_alloc(void)
1238 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1239 q->flags |= SIGQUEUE_PREALLOC;
1243 void sigqueue_free(struct sigqueue *q)
1245 unsigned long flags;
1246 spinlock_t *lock = ¤t->sighand->siglock;
1248 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1250 * If the signal is still pending remove it from the
1251 * pending queue. We must hold ->siglock while testing
1252 * q->list to serialize with collect_signal().
1254 spin_lock_irqsave(lock, flags);
1255 if (!list_empty(&q->list))
1256 list_del_init(&q->list);
1257 spin_unlock_irqrestore(lock, flags);
1259 q->flags &= ~SIGQUEUE_PREALLOC;
1263 static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
1266 struct sigpending *pending;
1268 handle_stop_signal(sig, t);
1270 if (unlikely(!list_empty(&q->list))) {
1272 * If an SI_TIMER entry is already queue just increment
1273 * the overrun count.
1276 BUG_ON(q->info.si_code != SI_TIMER);
1277 q->info.si_overrun++;
1281 if (sig_ignored(t, sig))
1284 signalfd_notify(t, sig);
1285 pending = group ? &t->signal->shared_pending : &t->pending;
1286 list_add_tail(&q->list, &pending->list);
1287 sigaddset(&pending->signal, sig);
1292 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1294 unsigned long flags;
1297 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1300 * The rcu based delayed sighand destroy makes it possible to
1301 * run this without tasklist lock held. The task struct itself
1302 * cannot go away as create_timer did get_task_struct().
1304 * We return -1, when the task is marked exiting, so
1305 * posix_timer_event can redirect it to the group leader
1307 if (!likely(lock_task_sighand(p, &flags)))
1310 ret = do_send_sigqueue(sig, q, p, 0);
1312 if (!sigismember(&p->blocked, sig))
1313 signal_wake_up(p, sig == SIGKILL);
1315 unlock_task_sighand(p, &flags);
1321 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1323 unsigned long flags;
1326 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1328 /* Since it_lock is held, p->sighand cannot be NULL. */
1329 spin_lock_irqsave(&p->sighand->siglock, flags);
1331 ret = do_send_sigqueue(sig, q, p, 1);
1333 __group_complete_signal(sig, p);
1335 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1341 * Wake up any threads in the parent blocked in wait* syscalls.
1343 static inline void __wake_up_parent(struct task_struct *p,
1344 struct task_struct *parent)
1346 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1350 * Let a parent know about the death of a child.
1351 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1354 void do_notify_parent(struct task_struct *tsk, int sig)
1356 struct siginfo info;
1357 unsigned long flags;
1358 struct sighand_struct *psig;
1362 /* do_notify_parent_cldstop should have been called instead. */
1363 BUG_ON(task_is_stopped_or_traced(tsk));
1365 BUG_ON(!tsk->ptrace &&
1366 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1368 info.si_signo = sig;
1371 * we are under tasklist_lock here so our parent is tied to
1372 * us and cannot exit and release its namespace.
1374 * the only it can is to switch its nsproxy with sys_unshare,
1375 * bu uncharing pid namespaces is not allowed, so we'll always
1376 * see relevant namespace
1378 * write_lock() currently calls preempt_disable() which is the
1379 * same as rcu_read_lock(), but according to Oleg, this is not
1380 * correct to rely on this
1383 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1386 info.si_uid = tsk->uid;
1388 /* FIXME: find out whether or not this is supposed to be c*time. */
1389 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1390 tsk->signal->utime));
1391 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1392 tsk->signal->stime));
1394 info.si_status = tsk->exit_code & 0x7f;
1395 if (tsk->exit_code & 0x80)
1396 info.si_code = CLD_DUMPED;
1397 else if (tsk->exit_code & 0x7f)
1398 info.si_code = CLD_KILLED;
1400 info.si_code = CLD_EXITED;
1401 info.si_status = tsk->exit_code >> 8;
1404 psig = tsk->parent->sighand;
1405 spin_lock_irqsave(&psig->siglock, flags);
1406 if (!tsk->ptrace && sig == SIGCHLD &&
1407 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1408 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1410 * We are exiting and our parent doesn't care. POSIX.1
1411 * defines special semantics for setting SIGCHLD to SIG_IGN
1412 * or setting the SA_NOCLDWAIT flag: we should be reaped
1413 * automatically and not left for our parent's wait4 call.
1414 * Rather than having the parent do it as a magic kind of
1415 * signal handler, we just set this to tell do_exit that we
1416 * can be cleaned up without becoming a zombie. Note that
1417 * we still call __wake_up_parent in this case, because a
1418 * blocked sys_wait4 might now return -ECHILD.
1420 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1421 * is implementation-defined: we do (if you don't want
1422 * it, just use SIG_IGN instead).
1424 tsk->exit_signal = -1;
1425 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1428 if (valid_signal(sig) && sig > 0)
1429 __group_send_sig_info(sig, &info, tsk->parent);
1430 __wake_up_parent(tsk, tsk->parent);
1431 spin_unlock_irqrestore(&psig->siglock, flags);
1434 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1436 struct siginfo info;
1437 unsigned long flags;
1438 struct task_struct *parent;
1439 struct sighand_struct *sighand;
1441 if (tsk->ptrace & PT_PTRACED)
1442 parent = tsk->parent;
1444 tsk = tsk->group_leader;
1445 parent = tsk->real_parent;
1448 info.si_signo = SIGCHLD;
1451 * see comment in do_notify_parent() abot the following 3 lines
1454 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1457 info.si_uid = tsk->uid;
1459 /* FIXME: find out whether or not this is supposed to be c*time. */
1460 info.si_utime = cputime_to_jiffies(tsk->utime);
1461 info.si_stime = cputime_to_jiffies(tsk->stime);
1466 info.si_status = SIGCONT;
1469 info.si_status = tsk->signal->group_exit_code & 0x7f;
1472 info.si_status = tsk->exit_code & 0x7f;
1478 sighand = parent->sighand;
1479 spin_lock_irqsave(&sighand->siglock, flags);
1480 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1481 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1482 __group_send_sig_info(SIGCHLD, &info, parent);
1484 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1486 __wake_up_parent(tsk, parent);
1487 spin_unlock_irqrestore(&sighand->siglock, flags);
1490 static inline int may_ptrace_stop(void)
1492 if (!likely(current->ptrace & PT_PTRACED))
1495 * Are we in the middle of do_coredump?
1496 * If so and our tracer is also part of the coredump stopping
1497 * is a deadlock situation, and pointless because our tracer
1498 * is dead so don't allow us to stop.
1499 * If SIGKILL was already sent before the caller unlocked
1500 * ->siglock we must see ->core_waiters != 0. Otherwise it
1501 * is safe to enter schedule().
1503 if (unlikely(current->mm->core_waiters) &&
1504 unlikely(current->mm == current->parent->mm))
1511 * Return nonzero if there is a SIGKILL that should be waking us up.
1512 * Called with the siglock held.
1514 static int sigkill_pending(struct task_struct *tsk)
1516 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1517 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1518 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1522 * This must be called with current->sighand->siglock held.
1524 * This should be the path for all ptrace stops.
1525 * We always set current->last_siginfo while stopped here.
1526 * That makes it a way to test a stopped process for
1527 * being ptrace-stopped vs being job-control-stopped.
1529 * If we actually decide not to stop at all because the tracer
1530 * is gone, we keep current->exit_code unless clear_code.
1532 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1536 if (arch_ptrace_stop_needed(exit_code, info)) {
1538 * The arch code has something special to do before a
1539 * ptrace stop. This is allowed to block, e.g. for faults
1540 * on user stack pages. We can't keep the siglock while
1541 * calling arch_ptrace_stop, so we must release it now.
1542 * To preserve proper semantics, we must do this before
1543 * any signal bookkeeping like checking group_stop_count.
1544 * Meanwhile, a SIGKILL could come in before we retake the
1545 * siglock. That must prevent us from sleeping in TASK_TRACED.
1546 * So after regaining the lock, we must check for SIGKILL.
1548 spin_unlock_irq(¤t->sighand->siglock);
1549 arch_ptrace_stop(exit_code, info);
1550 spin_lock_irq(¤t->sighand->siglock);
1551 killed = sigkill_pending(current);
1555 * If there is a group stop in progress,
1556 * we must participate in the bookkeeping.
1558 if (current->signal->group_stop_count > 0)
1559 --current->signal->group_stop_count;
1561 current->last_siginfo = info;
1562 current->exit_code = exit_code;
1564 /* Let the debugger run. */
1565 __set_current_state(TASK_TRACED);
1566 spin_unlock_irq(¤t->sighand->siglock);
1567 read_lock(&tasklist_lock);
1568 if (!unlikely(killed) && may_ptrace_stop()) {
1569 do_notify_parent_cldstop(current, CLD_TRAPPED);
1570 read_unlock(&tasklist_lock);
1574 * By the time we got the lock, our tracer went away.
1575 * Don't drop the lock yet, another tracer may come.
1577 __set_current_state(TASK_RUNNING);
1579 current->exit_code = 0;
1580 read_unlock(&tasklist_lock);
1584 * While in TASK_TRACED, we were considered "frozen enough".
1585 * Now that we woke up, it's crucial if we're supposed to be
1586 * frozen that we freeze now before running anything substantial.
1591 * We are back. Now reacquire the siglock before touching
1592 * last_siginfo, so that we are sure to have synchronized with
1593 * any signal-sending on another CPU that wants to examine it.
1595 spin_lock_irq(¤t->sighand->siglock);
1596 current->last_siginfo = NULL;
1599 * Queued signals ignored us while we were stopped for tracing.
1600 * So check for any that we should take before resuming user mode.
1601 * This sets TIF_SIGPENDING, but never clears it.
1603 recalc_sigpending_tsk(current);
1606 void ptrace_notify(int exit_code)
1610 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1612 memset(&info, 0, sizeof info);
1613 info.si_signo = SIGTRAP;
1614 info.si_code = exit_code;
1615 info.si_pid = task_pid_vnr(current);
1616 info.si_uid = current->uid;
1618 /* Let the debugger run. */
1619 spin_lock_irq(¤t->sighand->siglock);
1620 ptrace_stop(exit_code, 1, &info);
1621 spin_unlock_irq(¤t->sighand->siglock);
1625 finish_stop(int stop_count)
1628 * If there are no other threads in the group, or if there is
1629 * a group stop in progress and we are the last to stop,
1630 * report to the parent. When ptraced, every thread reports itself.
1632 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1633 read_lock(&tasklist_lock);
1634 do_notify_parent_cldstop(current, CLD_STOPPED);
1635 read_unlock(&tasklist_lock);
1640 } while (try_to_freeze());
1642 * Now we don't run again until continued.
1644 current->exit_code = 0;
1648 * This performs the stopping for SIGSTOP and other stop signals.
1649 * We have to stop all threads in the thread group.
1650 * Returns nonzero if we've actually stopped and released the siglock.
1651 * Returns zero if we didn't stop and still hold the siglock.
1653 static int do_signal_stop(int signr)
1655 struct signal_struct *sig = current->signal;
1658 if (sig->group_stop_count > 0) {
1660 * There is a group stop in progress. We don't need to
1661 * start another one.
1663 stop_count = --sig->group_stop_count;
1665 struct task_struct *t;
1667 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1668 unlikely(signal_group_exit(sig)))
1671 * There is no group stop already in progress.
1672 * We must initiate one now.
1674 sig->group_exit_code = signr;
1677 for (t = next_thread(current); t != current; t = next_thread(t))
1679 * Setting state to TASK_STOPPED for a group
1680 * stop is always done with the siglock held,
1681 * so this check has no races.
1683 if (!(t->flags & PF_EXITING) &&
1684 !task_is_stopped_or_traced(t)) {
1686 signal_wake_up(t, 0);
1688 sig->group_stop_count = stop_count;
1691 if (stop_count == 0)
1692 sig->flags = SIGNAL_STOP_STOPPED;
1693 current->exit_code = sig->group_exit_code;
1694 __set_current_state(TASK_STOPPED);
1696 spin_unlock_irq(¤t->sighand->siglock);
1697 finish_stop(stop_count);
1701 static int ptrace_signal(int signr, siginfo_t *info,
1702 struct pt_regs *regs, void *cookie)
1704 if (!(current->ptrace & PT_PTRACED))
1707 ptrace_signal_deliver(regs, cookie);
1709 /* Let the debugger run. */
1710 ptrace_stop(signr, 0, info);
1712 /* We're back. Did the debugger cancel the sig? */
1713 signr = current->exit_code;
1717 current->exit_code = 0;
1719 /* Update the siginfo structure if the signal has
1720 changed. If the debugger wanted something
1721 specific in the siginfo structure then it should
1722 have updated *info via PTRACE_SETSIGINFO. */
1723 if (signr != info->si_signo) {
1724 info->si_signo = signr;
1726 info->si_code = SI_USER;
1727 info->si_pid = task_pid_vnr(current->parent);
1728 info->si_uid = current->parent->uid;
1731 /* If the (new) signal is now blocked, requeue it. */
1732 if (sigismember(¤t->blocked, signr)) {
1733 specific_send_sig_info(signr, info, current);
1740 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1741 struct pt_regs *regs, void *cookie)
1743 struct sighand_struct *sighand = current->sighand;
1744 struct signal_struct *signal = current->signal;
1749 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1750 * While in TASK_STOPPED, we were considered "frozen enough".
1751 * Now that we woke up, it's crucial if we're supposed to be
1752 * frozen that we freeze now before running anything substantial.
1756 spin_lock_irq(&sighand->siglock);
1758 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1759 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1760 ? CLD_CONTINUED : CLD_STOPPED;
1761 signal->flags &= ~SIGNAL_CLD_MASK;
1762 spin_unlock_irq(&sighand->siglock);
1764 read_lock(&tasklist_lock);
1765 do_notify_parent_cldstop(current->group_leader, why);
1766 read_unlock(&tasklist_lock);
1771 struct k_sigaction *ka;
1773 if (unlikely(signal->group_stop_count > 0) &&
1777 signr = dequeue_signal(current, ¤t->blocked, info);
1779 break; /* will return 0 */
1781 if (signr != SIGKILL) {
1782 signr = ptrace_signal(signr, info, regs, cookie);
1787 ka = &sighand->action[signr-1];
1788 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1790 if (ka->sa.sa_handler != SIG_DFL) {
1791 /* Run the handler. */
1794 if (ka->sa.sa_flags & SA_ONESHOT)
1795 ka->sa.sa_handler = SIG_DFL;
1797 break; /* will return non-zero "signr" value */
1801 * Now we are doing the default action for this signal.
1803 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1807 * Global init gets no signals it doesn't want.
1809 if (is_global_init(current))
1812 if (sig_kernel_stop(signr)) {
1814 * The default action is to stop all threads in
1815 * the thread group. The job control signals
1816 * do nothing in an orphaned pgrp, but SIGSTOP
1817 * always works. Note that siglock needs to be
1818 * dropped during the call to is_orphaned_pgrp()
1819 * because of lock ordering with tasklist_lock.
1820 * This allows an intervening SIGCONT to be posted.
1821 * We need to check for that and bail out if necessary.
1823 if (signr != SIGSTOP) {
1824 spin_unlock_irq(&sighand->siglock);
1826 /* signals can be posted during this window */
1828 if (is_current_pgrp_orphaned())
1831 spin_lock_irq(&sighand->siglock);
1834 if (likely(do_signal_stop(signr))) {
1835 /* It released the siglock. */
1840 * We didn't actually stop, due to a race
1841 * with SIGCONT or something like that.
1846 spin_unlock_irq(&sighand->siglock);
1849 * Anything else is fatal, maybe with a core dump.
1851 current->flags |= PF_SIGNALED;
1852 if ((signr != SIGKILL) && print_fatal_signals)
1853 print_fatal_signal(regs, signr);
1854 if (sig_kernel_coredump(signr)) {
1856 * If it was able to dump core, this kills all
1857 * other threads in the group and synchronizes with
1858 * their demise. If we lost the race with another
1859 * thread getting here, it set group_exit_code
1860 * first and our do_group_exit call below will use
1861 * that value and ignore the one we pass it.
1863 do_coredump((long)signr, signr, regs);
1867 * Death signals, no core dump.
1869 do_group_exit(signr);
1872 spin_unlock_irq(&sighand->siglock);
1876 void exit_signals(struct task_struct *tsk)
1879 struct task_struct *t;
1881 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1882 tsk->flags |= PF_EXITING;
1886 spin_lock_irq(&tsk->sighand->siglock);
1888 * From now this task is not visible for group-wide signals,
1889 * see wants_signal(), do_signal_stop().
1891 tsk->flags |= PF_EXITING;
1892 if (!signal_pending(tsk))
1895 /* It could be that __group_complete_signal() choose us to
1896 * notify about group-wide signal. Another thread should be
1897 * woken now to take the signal since we will not.
1899 for (t = tsk; (t = next_thread(t)) != tsk; )
1900 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1901 recalc_sigpending_and_wake(t);
1903 if (unlikely(tsk->signal->group_stop_count) &&
1904 !--tsk->signal->group_stop_count) {
1905 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1909 spin_unlock_irq(&tsk->sighand->siglock);
1911 if (unlikely(group_stop)) {
1912 read_lock(&tasklist_lock);
1913 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1914 read_unlock(&tasklist_lock);
1918 EXPORT_SYMBOL(recalc_sigpending);
1919 EXPORT_SYMBOL_GPL(dequeue_signal);
1920 EXPORT_SYMBOL(flush_signals);
1921 EXPORT_SYMBOL(force_sig);
1922 EXPORT_SYMBOL(kill_proc);
1923 EXPORT_SYMBOL(ptrace_notify);
1924 EXPORT_SYMBOL(send_sig);
1925 EXPORT_SYMBOL(send_sig_info);
1926 EXPORT_SYMBOL(sigprocmask);
1927 EXPORT_SYMBOL(block_all_signals);
1928 EXPORT_SYMBOL(unblock_all_signals);
1932 * System call entry points.
1935 asmlinkage long sys_restart_syscall(void)
1937 struct restart_block *restart = ¤t_thread_info()->restart_block;
1938 return restart->fn(restart);
1941 long do_no_restart_syscall(struct restart_block *param)
1947 * We don't need to get the kernel lock - this is all local to this
1948 * particular thread.. (and that's good, because this is _heavily_
1949 * used by various programs)
1953 * This is also useful for kernel threads that want to temporarily
1954 * (or permanently) block certain signals.
1956 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1957 * interface happily blocks "unblockable" signals like SIGKILL
1960 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1964 spin_lock_irq(¤t->sighand->siglock);
1966 *oldset = current->blocked;
1971 sigorsets(¤t->blocked, ¤t->blocked, set);
1974 signandsets(¤t->blocked, ¤t->blocked, set);
1977 current->blocked = *set;
1982 recalc_sigpending();
1983 spin_unlock_irq(¤t->sighand->siglock);
1989 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1991 int error = -EINVAL;
1992 sigset_t old_set, new_set;
1994 /* XXX: Don't preclude handling different sized sigset_t's. */
1995 if (sigsetsize != sizeof(sigset_t))
2000 if (copy_from_user(&new_set, set, sizeof(*set)))
2002 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2004 error = sigprocmask(how, &new_set, &old_set);
2010 spin_lock_irq(¤t->sighand->siglock);
2011 old_set = current->blocked;
2012 spin_unlock_irq(¤t->sighand->siglock);
2016 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2024 long do_sigpending(void __user *set, unsigned long sigsetsize)
2026 long error = -EINVAL;
2029 if (sigsetsize > sizeof(sigset_t))
2032 spin_lock_irq(¤t->sighand->siglock);
2033 sigorsets(&pending, ¤t->pending.signal,
2034 ¤t->signal->shared_pending.signal);
2035 spin_unlock_irq(¤t->sighand->siglock);
2037 /* Outside the lock because only this thread touches it. */
2038 sigandsets(&pending, ¤t->blocked, &pending);
2041 if (!copy_to_user(set, &pending, sigsetsize))
2049 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2051 return do_sigpending(set, sigsetsize);
2054 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2056 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2060 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2062 if (from->si_code < 0)
2063 return __copy_to_user(to, from, sizeof(siginfo_t))
2066 * If you change siginfo_t structure, please be sure
2067 * this code is fixed accordingly.
2068 * Please remember to update the signalfd_copyinfo() function
2069 * inside fs/signalfd.c too, in case siginfo_t changes.
2070 * It should never copy any pad contained in the structure
2071 * to avoid security leaks, but must copy the generic
2072 * 3 ints plus the relevant union member.
2074 err = __put_user(from->si_signo, &to->si_signo);
2075 err |= __put_user(from->si_errno, &to->si_errno);
2076 err |= __put_user((short)from->si_code, &to->si_code);
2077 switch (from->si_code & __SI_MASK) {
2079 err |= __put_user(from->si_pid, &to->si_pid);
2080 err |= __put_user(from->si_uid, &to->si_uid);
2083 err |= __put_user(from->si_tid, &to->si_tid);
2084 err |= __put_user(from->si_overrun, &to->si_overrun);
2085 err |= __put_user(from->si_ptr, &to->si_ptr);
2088 err |= __put_user(from->si_band, &to->si_band);
2089 err |= __put_user(from->si_fd, &to->si_fd);
2092 err |= __put_user(from->si_addr, &to->si_addr);
2093 #ifdef __ARCH_SI_TRAPNO
2094 err |= __put_user(from->si_trapno, &to->si_trapno);
2098 err |= __put_user(from->si_pid, &to->si_pid);
2099 err |= __put_user(from->si_uid, &to->si_uid);
2100 err |= __put_user(from->si_status, &to->si_status);
2101 err |= __put_user(from->si_utime, &to->si_utime);
2102 err |= __put_user(from->si_stime, &to->si_stime);
2104 case __SI_RT: /* This is not generated by the kernel as of now. */
2105 case __SI_MESGQ: /* But this is */
2106 err |= __put_user(from->si_pid, &to->si_pid);
2107 err |= __put_user(from->si_uid, &to->si_uid);
2108 err |= __put_user(from->si_ptr, &to->si_ptr);
2110 default: /* this is just in case for now ... */
2111 err |= __put_user(from->si_pid, &to->si_pid);
2112 err |= __put_user(from->si_uid, &to->si_uid);
2121 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2122 siginfo_t __user *uinfo,
2123 const struct timespec __user *uts,
2132 /* XXX: Don't preclude handling different sized sigset_t's. */
2133 if (sigsetsize != sizeof(sigset_t))
2136 if (copy_from_user(&these, uthese, sizeof(these)))
2140 * Invert the set of allowed signals to get those we
2143 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2147 if (copy_from_user(&ts, uts, sizeof(ts)))
2149 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2154 spin_lock_irq(¤t->sighand->siglock);
2155 sig = dequeue_signal(current, &these, &info);
2157 timeout = MAX_SCHEDULE_TIMEOUT;
2159 timeout = (timespec_to_jiffies(&ts)
2160 + (ts.tv_sec || ts.tv_nsec));
2163 /* None ready -- temporarily unblock those we're
2164 * interested while we are sleeping in so that we'll
2165 * be awakened when they arrive. */
2166 current->real_blocked = current->blocked;
2167 sigandsets(¤t->blocked, ¤t->blocked, &these);
2168 recalc_sigpending();
2169 spin_unlock_irq(¤t->sighand->siglock);
2171 timeout = schedule_timeout_interruptible(timeout);
2173 spin_lock_irq(¤t->sighand->siglock);
2174 sig = dequeue_signal(current, &these, &info);
2175 current->blocked = current->real_blocked;
2176 siginitset(¤t->real_blocked, 0);
2177 recalc_sigpending();
2180 spin_unlock_irq(¤t->sighand->siglock);
2185 if (copy_siginfo_to_user(uinfo, &info))
2198 sys_kill(int pid, int sig)
2200 struct siginfo info;
2202 info.si_signo = sig;
2204 info.si_code = SI_USER;
2205 info.si_pid = task_tgid_vnr(current);
2206 info.si_uid = current->uid;
2208 return kill_something_info(sig, &info, pid);
2211 static int do_tkill(int tgid, int pid, int sig)
2214 struct siginfo info;
2215 struct task_struct *p;
2216 unsigned long flags;
2219 info.si_signo = sig;
2221 info.si_code = SI_TKILL;
2222 info.si_pid = task_tgid_vnr(current);
2223 info.si_uid = current->uid;
2226 p = find_task_by_vpid(pid);
2227 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2228 error = check_kill_permission(sig, &info, p);
2230 * The null signal is a permissions and process existence
2231 * probe. No signal is actually delivered.
2233 * If lock_task_sighand() fails we pretend the task dies
2234 * after receiving the signal. The window is tiny, and the
2235 * signal is private anyway.
2237 if (!error && sig && lock_task_sighand(p, &flags)) {
2238 error = specific_send_sig_info(sig, &info, p);
2239 unlock_task_sighand(p, &flags);
2248 * sys_tgkill - send signal to one specific thread
2249 * @tgid: the thread group ID of the thread
2250 * @pid: the PID of the thread
2251 * @sig: signal to be sent
2253 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2254 * exists but it's not belonging to the target process anymore. This
2255 * method solves the problem of threads exiting and PIDs getting reused.
2257 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2259 /* This is only valid for single tasks */
2260 if (pid <= 0 || tgid <= 0)
2263 return do_tkill(tgid, pid, sig);
2267 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2270 sys_tkill(int pid, int sig)
2272 /* This is only valid for single tasks */
2276 return do_tkill(0, pid, sig);
2280 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2284 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2287 /* Not even root can pretend to send signals from the kernel.
2288 Nor can they impersonate a kill(), which adds source info. */
2289 if (info.si_code >= 0)
2291 info.si_signo = sig;
2293 /* POSIX.1b doesn't mention process groups. */
2294 return kill_proc_info(sig, &info, pid);
2297 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2299 struct task_struct *t = current;
2300 struct k_sigaction *k;
2303 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2306 k = &t->sighand->action[sig-1];
2308 spin_lock_irq(¤t->sighand->siglock);
2313 sigdelsetmask(&act->sa.sa_mask,
2314 sigmask(SIGKILL) | sigmask(SIGSTOP));
2318 * "Setting a signal action to SIG_IGN for a signal that is
2319 * pending shall cause the pending signal to be discarded,
2320 * whether or not it is blocked."
2322 * "Setting a signal action to SIG_DFL for a signal that is
2323 * pending and whose default action is to ignore the signal
2324 * (for example, SIGCHLD), shall cause the pending signal to
2325 * be discarded, whether or not it is blocked"
2327 if (__sig_ignored(t, sig)) {
2329 sigaddset(&mask, sig);
2330 rm_from_queue_full(&mask, &t->signal->shared_pending);
2332 rm_from_queue_full(&mask, &t->pending);
2334 } while (t != current);
2338 spin_unlock_irq(¤t->sighand->siglock);
2343 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2349 oss.ss_sp = (void __user *) current->sas_ss_sp;
2350 oss.ss_size = current->sas_ss_size;
2351 oss.ss_flags = sas_ss_flags(sp);
2360 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2361 || __get_user(ss_sp, &uss->ss_sp)
2362 || __get_user(ss_flags, &uss->ss_flags)
2363 || __get_user(ss_size, &uss->ss_size))
2367 if (on_sig_stack(sp))
2373 * Note - this code used to test ss_flags incorrectly
2374 * old code may have been written using ss_flags==0
2375 * to mean ss_flags==SS_ONSTACK (as this was the only
2376 * way that worked) - this fix preserves that older
2379 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2382 if (ss_flags == SS_DISABLE) {
2387 if (ss_size < MINSIGSTKSZ)
2391 current->sas_ss_sp = (unsigned long) ss_sp;
2392 current->sas_ss_size = ss_size;
2397 if (copy_to_user(uoss, &oss, sizeof(oss)))
2406 #ifdef __ARCH_WANT_SYS_SIGPENDING
2409 sys_sigpending(old_sigset_t __user *set)
2411 return do_sigpending(set, sizeof(*set));
2416 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2417 /* Some platforms have their own version with special arguments others
2418 support only sys_rt_sigprocmask. */
2421 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2424 old_sigset_t old_set, new_set;
2428 if (copy_from_user(&new_set, set, sizeof(*set)))
2430 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2432 spin_lock_irq(¤t->sighand->siglock);
2433 old_set = current->blocked.sig[0];
2441 sigaddsetmask(¤t->blocked, new_set);
2444 sigdelsetmask(¤t->blocked, new_set);
2447 current->blocked.sig[0] = new_set;
2451 recalc_sigpending();
2452 spin_unlock_irq(¤t->sighand->siglock);
2458 old_set = current->blocked.sig[0];
2461 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2468 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2470 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2472 sys_rt_sigaction(int sig,
2473 const struct sigaction __user *act,
2474 struct sigaction __user *oact,
2477 struct k_sigaction new_sa, old_sa;
2480 /* XXX: Don't preclude handling different sized sigset_t's. */
2481 if (sigsetsize != sizeof(sigset_t))
2485 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2489 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2492 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2498 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2500 #ifdef __ARCH_WANT_SYS_SGETMASK
2503 * For backwards compatibility. Functionality superseded by sigprocmask.
2509 return current->blocked.sig[0];
2513 sys_ssetmask(int newmask)
2517 spin_lock_irq(¤t->sighand->siglock);
2518 old = current->blocked.sig[0];
2520 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2522 recalc_sigpending();
2523 spin_unlock_irq(¤t->sighand->siglock);
2527 #endif /* __ARCH_WANT_SGETMASK */
2529 #ifdef __ARCH_WANT_SYS_SIGNAL
2531 * For backwards compatibility. Functionality superseded by sigaction.
2533 asmlinkage unsigned long
2534 sys_signal(int sig, __sighandler_t handler)
2536 struct k_sigaction new_sa, old_sa;
2539 new_sa.sa.sa_handler = handler;
2540 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2541 sigemptyset(&new_sa.sa.sa_mask);
2543 ret = do_sigaction(sig, &new_sa, &old_sa);
2545 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2547 #endif /* __ARCH_WANT_SYS_SIGNAL */
2549 #ifdef __ARCH_WANT_SYS_PAUSE
2554 current->state = TASK_INTERRUPTIBLE;
2556 return -ERESTARTNOHAND;
2561 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2562 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2566 /* XXX: Don't preclude handling different sized sigset_t's. */
2567 if (sigsetsize != sizeof(sigset_t))
2570 if (copy_from_user(&newset, unewset, sizeof(newset)))
2572 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2574 spin_lock_irq(¤t->sighand->siglock);
2575 current->saved_sigmask = current->blocked;
2576 current->blocked = newset;
2577 recalc_sigpending();
2578 spin_unlock_irq(¤t->sighand->siglock);
2580 current->state = TASK_INTERRUPTIBLE;
2582 set_thread_flag(TIF_RESTORE_SIGMASK);
2583 return -ERESTARTNOHAND;
2585 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2587 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2592 void __init signals_init(void)
2594 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);