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;
655 static inline int legacy_queue(struct sigpending *signals, int sig)
657 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
660 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
661 struct sigpending *signals)
665 assert_spin_locked(&t->sighand->siglock);
666 handle_stop_signal(sig, t);
668 * Short-circuit ignored signals and support queuing
669 * exactly one non-rt signal, so that we can get more
670 * detailed information about the cause of the signal.
672 if (sig_ignored(t, sig) || legacy_queue(signals, sig))
676 * Deliver the signal to listening signalfds. This must be called
677 * with the sighand lock held.
679 signalfd_notify(t, sig);
682 * fast-pathed signals for kernel-internal things like SIGSTOP
685 if (info == SEND_SIG_FORCED)
688 /* Real-time signals must be queued if sent by sigqueue, or
689 some other real-time mechanism. It is implementation
690 defined whether kill() does so. We attempt to do so, on
691 the principle of least surprise, but since kill is not
692 allowed to fail with EAGAIN when low on memory we just
693 make sure at least one signal gets delivered and don't
694 pass on the info struct. */
696 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
697 (is_si_special(info) ||
698 info->si_code >= 0)));
700 list_add_tail(&q->list, &signals->list);
701 switch ((unsigned long) info) {
702 case (unsigned long) SEND_SIG_NOINFO:
703 q->info.si_signo = sig;
704 q->info.si_errno = 0;
705 q->info.si_code = SI_USER;
706 q->info.si_pid = task_pid_vnr(current);
707 q->info.si_uid = current->uid;
709 case (unsigned long) SEND_SIG_PRIV:
710 q->info.si_signo = sig;
711 q->info.si_errno = 0;
712 q->info.si_code = SI_KERNEL;
717 copy_siginfo(&q->info, info);
720 } else if (!is_si_special(info)) {
721 if (sig >= SIGRTMIN && info->si_code != SI_USER)
723 * Queue overflow, abort. We may abort if the signal was rt
724 * and sent by user using something other than kill().
730 sigaddset(&signals->signal, sig);
734 int print_fatal_signals;
736 static void print_fatal_signal(struct pt_regs *regs, int signr)
738 printk("%s/%d: potentially unexpected fatal signal %d.\n",
739 current->comm, task_pid_nr(current), signr);
741 #if defined(__i386__) && !defined(__arch_um__)
742 printk("code at %08lx: ", regs->ip);
745 for (i = 0; i < 16; i++) {
748 __get_user(insn, (unsigned char *)(regs->ip + i));
749 printk("%02x ", insn);
757 static int __init setup_print_fatal_signals(char *str)
759 get_option (&str, &print_fatal_signals);
764 __setup("print-fatal-signals=", setup_print_fatal_signals);
767 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
771 ret = send_signal(sig, info, t, &t->pending);
775 if (!sigismember(&t->blocked, sig))
776 signal_wake_up(t, sig == SIGKILL);
781 * Force a signal that the process can't ignore: if necessary
782 * we unblock the signal and change any SIG_IGN to SIG_DFL.
784 * Note: If we unblock the signal, we always reset it to SIG_DFL,
785 * since we do not want to have a signal handler that was blocked
786 * be invoked when user space had explicitly blocked it.
788 * We don't want to have recursive SIGSEGV's etc, for example.
791 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
793 unsigned long int flags;
794 int ret, blocked, ignored;
795 struct k_sigaction *action;
797 spin_lock_irqsave(&t->sighand->siglock, flags);
798 action = &t->sighand->action[sig-1];
799 ignored = action->sa.sa_handler == SIG_IGN;
800 blocked = sigismember(&t->blocked, sig);
801 if (blocked || ignored) {
802 action->sa.sa_handler = SIG_DFL;
804 sigdelset(&t->blocked, sig);
805 recalc_sigpending_and_wake(t);
808 ret = specific_send_sig_info(sig, info, t);
809 spin_unlock_irqrestore(&t->sighand->siglock, flags);
815 force_sig_specific(int sig, struct task_struct *t)
817 force_sig_info(sig, SEND_SIG_FORCED, t);
821 * Test if P wants to take SIG. After we've checked all threads with this,
822 * it's equivalent to finding no threads not blocking SIG. Any threads not
823 * blocking SIG were ruled out because they are not running and already
824 * have pending signals. Such threads will dequeue from the shared queue
825 * as soon as they're available, so putting the signal on the shared queue
826 * will be equivalent to sending it to one such thread.
828 static inline int wants_signal(int sig, struct task_struct *p)
830 if (sigismember(&p->blocked, sig))
832 if (p->flags & PF_EXITING)
836 if (task_is_stopped_or_traced(p))
838 return task_curr(p) || !signal_pending(p);
842 __group_complete_signal(int sig, struct task_struct *p)
844 struct signal_struct *signal = p->signal;
845 struct task_struct *t;
848 * Now find a thread we can wake up to take the signal off the queue.
850 * If the main thread wants the signal, it gets first crack.
851 * Probably the least surprising to the average bear.
853 if (wants_signal(sig, p))
855 else if (thread_group_empty(p))
857 * There is just one thread and it does not need to be woken.
858 * It will dequeue unblocked signals before it runs again.
863 * Otherwise try to find a suitable thread.
865 t = signal->curr_target;
867 /* restart balancing at this thread */
868 t = signal->curr_target = p;
870 while (!wants_signal(sig, t)) {
872 if (t == signal->curr_target)
874 * No thread needs to be woken.
875 * Any eligible threads will see
876 * the signal in the queue soon.
880 signal->curr_target = t;
884 * Found a killable thread. If the signal will be fatal,
885 * then start taking the whole group down immediately.
887 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
888 !sigismember(&t->real_blocked, sig) &&
889 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
891 * This signal will be fatal to the whole group.
893 if (!sig_kernel_coredump(sig)) {
895 * Start a group exit and wake everybody up.
896 * This way we don't have other threads
897 * running and doing things after a slower
898 * thread has the fatal signal pending.
900 signal->flags = SIGNAL_GROUP_EXIT;
901 signal->group_exit_code = sig;
902 signal->group_stop_count = 0;
905 sigaddset(&t->pending.signal, SIGKILL);
906 signal_wake_up(t, 1);
907 } while_each_thread(p, t);
913 * The signal is already in the shared-pending queue.
914 * Tell the chosen thread to wake up and dequeue it.
916 signal_wake_up(t, sig == SIGKILL);
921 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
926 * Put this signal on the shared-pending queue, or fail with EAGAIN.
927 * We always use the shared queue for process-wide signals,
928 * to avoid several races.
930 ret = send_signal(sig, info, p, &p->signal->shared_pending);
934 __group_complete_signal(sig, p);
939 * Nuke all other threads in the group.
941 void zap_other_threads(struct task_struct *p)
943 struct task_struct *t;
945 p->signal->group_stop_count = 0;
947 for (t = next_thread(p); t != p; t = next_thread(t)) {
949 * Don't bother with already dead threads
954 /* SIGKILL will be handled before any pending SIGSTOP */
955 sigaddset(&t->pending.signal, SIGKILL);
956 signal_wake_up(t, 1);
960 int __fatal_signal_pending(struct task_struct *tsk)
962 return sigismember(&tsk->pending.signal, SIGKILL);
964 EXPORT_SYMBOL(__fatal_signal_pending);
966 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
968 struct sighand_struct *sighand;
972 sighand = rcu_dereference(tsk->sighand);
973 if (unlikely(sighand == NULL))
976 spin_lock_irqsave(&sighand->siglock, *flags);
977 if (likely(sighand == tsk->sighand))
979 spin_unlock_irqrestore(&sighand->siglock, *flags);
986 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
991 ret = check_kill_permission(sig, info, p);
995 if (lock_task_sighand(p, &flags)) {
996 ret = __group_send_sig_info(sig, info, p);
997 unlock_task_sighand(p, &flags);
1005 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1006 * control characters do (^C, ^Z etc)
1009 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1011 struct task_struct *p = NULL;
1012 int retval, success;
1016 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1017 int err = group_send_sig_info(sig, info, p);
1020 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1021 return success ? 0 : retval;
1024 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1027 struct task_struct *p;
1031 p = pid_task(pid, PIDTYPE_PID);
1033 error = group_send_sig_info(sig, info, p);
1034 if (unlikely(error == -ESRCH))
1036 * The task was unhashed in between, try again.
1037 * If it is dead, pid_task() will return NULL,
1038 * if we race with de_thread() it will find the
1049 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1053 error = kill_pid_info(sig, info, find_vpid(pid));
1058 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1059 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1060 uid_t uid, uid_t euid, u32 secid)
1063 struct task_struct *p;
1065 if (!valid_signal(sig))
1068 read_lock(&tasklist_lock);
1069 p = pid_task(pid, PIDTYPE_PID);
1074 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1075 && (euid != p->suid) && (euid != p->uid)
1076 && (uid != p->suid) && (uid != p->uid)) {
1080 ret = security_task_kill(p, info, sig, secid);
1083 if (sig && p->sighand) {
1084 unsigned long flags;
1085 spin_lock_irqsave(&p->sighand->siglock, flags);
1086 ret = __group_send_sig_info(sig, info, p);
1087 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1090 read_unlock(&tasklist_lock);
1093 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1096 * kill_something_info() interprets pid in interesting ways just like kill(2).
1098 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1099 * is probably wrong. Should make it like BSD or SYSV.
1102 static int kill_something_info(int sig, struct siginfo *info, int pid)
1108 ret = kill_pid_info(sig, info, find_vpid(pid));
1113 read_lock(&tasklist_lock);
1115 ret = __kill_pgrp_info(sig, info,
1116 pid ? find_vpid(-pid) : task_pgrp(current));
1118 int retval = 0, count = 0;
1119 struct task_struct * p;
1121 for_each_process(p) {
1122 if (p->pid > 1 && !same_thread_group(p, current)) {
1123 int err = group_send_sig_info(sig, info, p);
1129 ret = count ? retval : -ESRCH;
1131 read_unlock(&tasklist_lock);
1137 * These are for backward compatibility with the rest of the kernel source.
1141 * The caller must ensure the task can't exit.
1144 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1147 unsigned long flags;
1150 * Make sure legacy kernel users don't send in bad values
1151 * (normal paths check this in check_kill_permission).
1153 if (!valid_signal(sig))
1156 spin_lock_irqsave(&p->sighand->siglock, flags);
1157 ret = specific_send_sig_info(sig, info, p);
1158 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1162 #define __si_special(priv) \
1163 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1166 send_sig(int sig, struct task_struct *p, int priv)
1168 return send_sig_info(sig, __si_special(priv), p);
1172 force_sig(int sig, struct task_struct *p)
1174 force_sig_info(sig, SEND_SIG_PRIV, p);
1178 * When things go south during signal handling, we
1179 * will force a SIGSEGV. And if the signal that caused
1180 * the problem was already a SIGSEGV, we'll want to
1181 * make sure we don't even try to deliver the signal..
1184 force_sigsegv(int sig, struct task_struct *p)
1186 if (sig == SIGSEGV) {
1187 unsigned long flags;
1188 spin_lock_irqsave(&p->sighand->siglock, flags);
1189 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1190 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1192 force_sig(SIGSEGV, p);
1196 int kill_pgrp(struct pid *pid, int sig, int priv)
1200 read_lock(&tasklist_lock);
1201 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1202 read_unlock(&tasklist_lock);
1206 EXPORT_SYMBOL(kill_pgrp);
1208 int kill_pid(struct pid *pid, int sig, int priv)
1210 return kill_pid_info(sig, __si_special(priv), pid);
1212 EXPORT_SYMBOL(kill_pid);
1215 kill_proc(pid_t pid, int sig, int priv)
1220 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1226 * These functions support sending signals using preallocated sigqueue
1227 * structures. This is needed "because realtime applications cannot
1228 * afford to lose notifications of asynchronous events, like timer
1229 * expirations or I/O completions". In the case of Posix Timers
1230 * we allocate the sigqueue structure from the timer_create. If this
1231 * allocation fails we are able to report the failure to the application
1232 * with an EAGAIN error.
1235 struct sigqueue *sigqueue_alloc(void)
1239 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1240 q->flags |= SIGQUEUE_PREALLOC;
1244 void sigqueue_free(struct sigqueue *q)
1246 unsigned long flags;
1247 spinlock_t *lock = ¤t->sighand->siglock;
1249 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1251 * If the signal is still pending remove it from the
1252 * pending queue. We must hold ->siglock while testing
1253 * q->list to serialize with collect_signal().
1255 spin_lock_irqsave(lock, flags);
1256 if (!list_empty(&q->list))
1257 list_del_init(&q->list);
1258 spin_unlock_irqrestore(lock, flags);
1260 q->flags &= ~SIGQUEUE_PREALLOC;
1264 static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
1265 struct sigpending *pending)
1267 handle_stop_signal(sig, t);
1269 if (unlikely(!list_empty(&q->list))) {
1271 * If an SI_TIMER entry is already queue just increment
1272 * the overrun count.
1275 BUG_ON(q->info.si_code != SI_TIMER);
1276 q->info.si_overrun++;
1280 if (sig_ignored(t, sig))
1283 signalfd_notify(t, sig);
1284 list_add_tail(&q->list, &pending->list);
1285 sigaddset(&pending->signal, sig);
1289 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1291 unsigned long flags;
1294 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1297 * The rcu based delayed sighand destroy makes it possible to
1298 * run this without tasklist lock held. The task struct itself
1299 * cannot go away as create_timer did get_task_struct().
1301 * We return -1, when the task is marked exiting, so
1302 * posix_timer_event can redirect it to the group leader
1304 if (!likely(lock_task_sighand(p, &flags)))
1307 ret = do_send_sigqueue(sig, q, p, &p->pending);
1309 if (!sigismember(&p->blocked, sig))
1310 signal_wake_up(p, sig == SIGKILL);
1312 unlock_task_sighand(p, &flags);
1318 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1320 unsigned long flags;
1323 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1325 /* Since it_lock is held, p->sighand cannot be NULL. */
1326 spin_lock_irqsave(&p->sighand->siglock, flags);
1328 ret = do_send_sigqueue(sig, q, p, &p->signal->shared_pending);
1330 __group_complete_signal(sig, p);
1332 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1338 * Wake up any threads in the parent blocked in wait* syscalls.
1340 static inline void __wake_up_parent(struct task_struct *p,
1341 struct task_struct *parent)
1343 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1347 * Let a parent know about the death of a child.
1348 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1351 void do_notify_parent(struct task_struct *tsk, int sig)
1353 struct siginfo info;
1354 unsigned long flags;
1355 struct sighand_struct *psig;
1359 /* do_notify_parent_cldstop should have been called instead. */
1360 BUG_ON(task_is_stopped_or_traced(tsk));
1362 BUG_ON(!tsk->ptrace &&
1363 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1365 info.si_signo = sig;
1368 * we are under tasklist_lock here so our parent is tied to
1369 * us and cannot exit and release its namespace.
1371 * the only it can is to switch its nsproxy with sys_unshare,
1372 * bu uncharing pid namespaces is not allowed, so we'll always
1373 * see relevant namespace
1375 * write_lock() currently calls preempt_disable() which is the
1376 * same as rcu_read_lock(), but according to Oleg, this is not
1377 * correct to rely on this
1380 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1383 info.si_uid = tsk->uid;
1385 /* FIXME: find out whether or not this is supposed to be c*time. */
1386 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1387 tsk->signal->utime));
1388 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1389 tsk->signal->stime));
1391 info.si_status = tsk->exit_code & 0x7f;
1392 if (tsk->exit_code & 0x80)
1393 info.si_code = CLD_DUMPED;
1394 else if (tsk->exit_code & 0x7f)
1395 info.si_code = CLD_KILLED;
1397 info.si_code = CLD_EXITED;
1398 info.si_status = tsk->exit_code >> 8;
1401 psig = tsk->parent->sighand;
1402 spin_lock_irqsave(&psig->siglock, flags);
1403 if (!tsk->ptrace && sig == SIGCHLD &&
1404 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1405 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1407 * We are exiting and our parent doesn't care. POSIX.1
1408 * defines special semantics for setting SIGCHLD to SIG_IGN
1409 * or setting the SA_NOCLDWAIT flag: we should be reaped
1410 * automatically and not left for our parent's wait4 call.
1411 * Rather than having the parent do it as a magic kind of
1412 * signal handler, we just set this to tell do_exit that we
1413 * can be cleaned up without becoming a zombie. Note that
1414 * we still call __wake_up_parent in this case, because a
1415 * blocked sys_wait4 might now return -ECHILD.
1417 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1418 * is implementation-defined: we do (if you don't want
1419 * it, just use SIG_IGN instead).
1421 tsk->exit_signal = -1;
1422 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1425 if (valid_signal(sig) && sig > 0)
1426 __group_send_sig_info(sig, &info, tsk->parent);
1427 __wake_up_parent(tsk, tsk->parent);
1428 spin_unlock_irqrestore(&psig->siglock, flags);
1431 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1433 struct siginfo info;
1434 unsigned long flags;
1435 struct task_struct *parent;
1436 struct sighand_struct *sighand;
1438 if (tsk->ptrace & PT_PTRACED)
1439 parent = tsk->parent;
1441 tsk = tsk->group_leader;
1442 parent = tsk->real_parent;
1445 info.si_signo = SIGCHLD;
1448 * see comment in do_notify_parent() abot the following 3 lines
1451 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1454 info.si_uid = tsk->uid;
1456 /* FIXME: find out whether or not this is supposed to be c*time. */
1457 info.si_utime = cputime_to_jiffies(tsk->utime);
1458 info.si_stime = cputime_to_jiffies(tsk->stime);
1463 info.si_status = SIGCONT;
1466 info.si_status = tsk->signal->group_exit_code & 0x7f;
1469 info.si_status = tsk->exit_code & 0x7f;
1475 sighand = parent->sighand;
1476 spin_lock_irqsave(&sighand->siglock, flags);
1477 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1478 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1479 __group_send_sig_info(SIGCHLD, &info, parent);
1481 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1483 __wake_up_parent(tsk, parent);
1484 spin_unlock_irqrestore(&sighand->siglock, flags);
1487 static inline int may_ptrace_stop(void)
1489 if (!likely(current->ptrace & PT_PTRACED))
1492 * Are we in the middle of do_coredump?
1493 * If so and our tracer is also part of the coredump stopping
1494 * is a deadlock situation, and pointless because our tracer
1495 * is dead so don't allow us to stop.
1496 * If SIGKILL was already sent before the caller unlocked
1497 * ->siglock we must see ->core_waiters != 0. Otherwise it
1498 * is safe to enter schedule().
1500 if (unlikely(current->mm->core_waiters) &&
1501 unlikely(current->mm == current->parent->mm))
1508 * Return nonzero if there is a SIGKILL that should be waking us up.
1509 * Called with the siglock held.
1511 static int sigkill_pending(struct task_struct *tsk)
1513 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1514 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1515 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1519 * This must be called with current->sighand->siglock held.
1521 * This should be the path for all ptrace stops.
1522 * We always set current->last_siginfo while stopped here.
1523 * That makes it a way to test a stopped process for
1524 * being ptrace-stopped vs being job-control-stopped.
1526 * If we actually decide not to stop at all because the tracer
1527 * is gone, we keep current->exit_code unless clear_code.
1529 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1533 if (arch_ptrace_stop_needed(exit_code, info)) {
1535 * The arch code has something special to do before a
1536 * ptrace stop. This is allowed to block, e.g. for faults
1537 * on user stack pages. We can't keep the siglock while
1538 * calling arch_ptrace_stop, so we must release it now.
1539 * To preserve proper semantics, we must do this before
1540 * any signal bookkeeping like checking group_stop_count.
1541 * Meanwhile, a SIGKILL could come in before we retake the
1542 * siglock. That must prevent us from sleeping in TASK_TRACED.
1543 * So after regaining the lock, we must check for SIGKILL.
1545 spin_unlock_irq(¤t->sighand->siglock);
1546 arch_ptrace_stop(exit_code, info);
1547 spin_lock_irq(¤t->sighand->siglock);
1548 killed = sigkill_pending(current);
1552 * If there is a group stop in progress,
1553 * we must participate in the bookkeeping.
1555 if (current->signal->group_stop_count > 0)
1556 --current->signal->group_stop_count;
1558 current->last_siginfo = info;
1559 current->exit_code = exit_code;
1561 /* Let the debugger run. */
1562 __set_current_state(TASK_TRACED);
1563 spin_unlock_irq(¤t->sighand->siglock);
1564 read_lock(&tasklist_lock);
1565 if (!unlikely(killed) && may_ptrace_stop()) {
1566 do_notify_parent_cldstop(current, CLD_TRAPPED);
1567 read_unlock(&tasklist_lock);
1571 * By the time we got the lock, our tracer went away.
1572 * Don't drop the lock yet, another tracer may come.
1574 __set_current_state(TASK_RUNNING);
1576 current->exit_code = 0;
1577 read_unlock(&tasklist_lock);
1581 * While in TASK_TRACED, we were considered "frozen enough".
1582 * Now that we woke up, it's crucial if we're supposed to be
1583 * frozen that we freeze now before running anything substantial.
1588 * We are back. Now reacquire the siglock before touching
1589 * last_siginfo, so that we are sure to have synchronized with
1590 * any signal-sending on another CPU that wants to examine it.
1592 spin_lock_irq(¤t->sighand->siglock);
1593 current->last_siginfo = NULL;
1596 * Queued signals ignored us while we were stopped for tracing.
1597 * So check for any that we should take before resuming user mode.
1598 * This sets TIF_SIGPENDING, but never clears it.
1600 recalc_sigpending_tsk(current);
1603 void ptrace_notify(int exit_code)
1607 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1609 memset(&info, 0, sizeof info);
1610 info.si_signo = SIGTRAP;
1611 info.si_code = exit_code;
1612 info.si_pid = task_pid_vnr(current);
1613 info.si_uid = current->uid;
1615 /* Let the debugger run. */
1616 spin_lock_irq(¤t->sighand->siglock);
1617 ptrace_stop(exit_code, 1, &info);
1618 spin_unlock_irq(¤t->sighand->siglock);
1622 finish_stop(int stop_count)
1625 * If there are no other threads in the group, or if there is
1626 * a group stop in progress and we are the last to stop,
1627 * report to the parent. When ptraced, every thread reports itself.
1629 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1630 read_lock(&tasklist_lock);
1631 do_notify_parent_cldstop(current, CLD_STOPPED);
1632 read_unlock(&tasklist_lock);
1637 } while (try_to_freeze());
1639 * Now we don't run again until continued.
1641 current->exit_code = 0;
1645 * This performs the stopping for SIGSTOP and other stop signals.
1646 * We have to stop all threads in the thread group.
1647 * Returns nonzero if we've actually stopped and released the siglock.
1648 * Returns zero if we didn't stop and still hold the siglock.
1650 static int do_signal_stop(int signr)
1652 struct signal_struct *sig = current->signal;
1655 if (sig->group_stop_count > 0) {
1657 * There is a group stop in progress. We don't need to
1658 * start another one.
1660 stop_count = --sig->group_stop_count;
1662 struct task_struct *t;
1664 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1665 unlikely(signal_group_exit(sig)))
1668 * There is no group stop already in progress.
1669 * We must initiate one now.
1671 sig->group_exit_code = signr;
1674 for (t = next_thread(current); t != current; t = next_thread(t))
1676 * Setting state to TASK_STOPPED for a group
1677 * stop is always done with the siglock held,
1678 * so this check has no races.
1680 if (!(t->flags & PF_EXITING) &&
1681 !task_is_stopped_or_traced(t)) {
1683 signal_wake_up(t, 0);
1685 sig->group_stop_count = stop_count;
1688 if (stop_count == 0)
1689 sig->flags = SIGNAL_STOP_STOPPED;
1690 current->exit_code = sig->group_exit_code;
1691 __set_current_state(TASK_STOPPED);
1693 spin_unlock_irq(¤t->sighand->siglock);
1694 finish_stop(stop_count);
1698 static int ptrace_signal(int signr, siginfo_t *info,
1699 struct pt_regs *regs, void *cookie)
1701 if (!(current->ptrace & PT_PTRACED))
1704 ptrace_signal_deliver(regs, cookie);
1706 /* Let the debugger run. */
1707 ptrace_stop(signr, 0, info);
1709 /* We're back. Did the debugger cancel the sig? */
1710 signr = current->exit_code;
1714 current->exit_code = 0;
1716 /* Update the siginfo structure if the signal has
1717 changed. If the debugger wanted something
1718 specific in the siginfo structure then it should
1719 have updated *info via PTRACE_SETSIGINFO. */
1720 if (signr != info->si_signo) {
1721 info->si_signo = signr;
1723 info->si_code = SI_USER;
1724 info->si_pid = task_pid_vnr(current->parent);
1725 info->si_uid = current->parent->uid;
1728 /* If the (new) signal is now blocked, requeue it. */
1729 if (sigismember(¤t->blocked, signr)) {
1730 specific_send_sig_info(signr, info, current);
1737 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1738 struct pt_regs *regs, void *cookie)
1740 struct sighand_struct *sighand = current->sighand;
1741 struct signal_struct *signal = current->signal;
1746 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1747 * While in TASK_STOPPED, we were considered "frozen enough".
1748 * Now that we woke up, it's crucial if we're supposed to be
1749 * frozen that we freeze now before running anything substantial.
1753 spin_lock_irq(&sighand->siglock);
1755 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1756 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1757 ? CLD_CONTINUED : CLD_STOPPED;
1758 signal->flags &= ~SIGNAL_CLD_MASK;
1759 spin_unlock_irq(&sighand->siglock);
1761 read_lock(&tasklist_lock);
1762 do_notify_parent_cldstop(current->group_leader, why);
1763 read_unlock(&tasklist_lock);
1768 struct k_sigaction *ka;
1770 if (unlikely(signal->group_stop_count > 0) &&
1774 signr = dequeue_signal(current, ¤t->blocked, info);
1776 break; /* will return 0 */
1778 if (signr != SIGKILL) {
1779 signr = ptrace_signal(signr, info, regs, cookie);
1784 ka = &sighand->action[signr-1];
1785 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1787 if (ka->sa.sa_handler != SIG_DFL) {
1788 /* Run the handler. */
1791 if (ka->sa.sa_flags & SA_ONESHOT)
1792 ka->sa.sa_handler = SIG_DFL;
1794 break; /* will return non-zero "signr" value */
1798 * Now we are doing the default action for this signal.
1800 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1804 * Global init gets no signals it doesn't want.
1806 if (is_global_init(current))
1809 if (sig_kernel_stop(signr)) {
1811 * The default action is to stop all threads in
1812 * the thread group. The job control signals
1813 * do nothing in an orphaned pgrp, but SIGSTOP
1814 * always works. Note that siglock needs to be
1815 * dropped during the call to is_orphaned_pgrp()
1816 * because of lock ordering with tasklist_lock.
1817 * This allows an intervening SIGCONT to be posted.
1818 * We need to check for that and bail out if necessary.
1820 if (signr != SIGSTOP) {
1821 spin_unlock_irq(&sighand->siglock);
1823 /* signals can be posted during this window */
1825 if (is_current_pgrp_orphaned())
1828 spin_lock_irq(&sighand->siglock);
1831 if (likely(do_signal_stop(signr))) {
1832 /* It released the siglock. */
1837 * We didn't actually stop, due to a race
1838 * with SIGCONT or something like that.
1843 spin_unlock_irq(&sighand->siglock);
1846 * Anything else is fatal, maybe with a core dump.
1848 current->flags |= PF_SIGNALED;
1849 if ((signr != SIGKILL) && print_fatal_signals)
1850 print_fatal_signal(regs, signr);
1851 if (sig_kernel_coredump(signr)) {
1853 * If it was able to dump core, this kills all
1854 * other threads in the group and synchronizes with
1855 * their demise. If we lost the race with another
1856 * thread getting here, it set group_exit_code
1857 * first and our do_group_exit call below will use
1858 * that value and ignore the one we pass it.
1860 do_coredump((long)signr, signr, regs);
1864 * Death signals, no core dump.
1866 do_group_exit(signr);
1869 spin_unlock_irq(&sighand->siglock);
1873 void exit_signals(struct task_struct *tsk)
1876 struct task_struct *t;
1878 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1879 tsk->flags |= PF_EXITING;
1883 spin_lock_irq(&tsk->sighand->siglock);
1885 * From now this task is not visible for group-wide signals,
1886 * see wants_signal(), do_signal_stop().
1888 tsk->flags |= PF_EXITING;
1889 if (!signal_pending(tsk))
1892 /* It could be that __group_complete_signal() choose us to
1893 * notify about group-wide signal. Another thread should be
1894 * woken now to take the signal since we will not.
1896 for (t = tsk; (t = next_thread(t)) != tsk; )
1897 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1898 recalc_sigpending_and_wake(t);
1900 if (unlikely(tsk->signal->group_stop_count) &&
1901 !--tsk->signal->group_stop_count) {
1902 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1906 spin_unlock_irq(&tsk->sighand->siglock);
1908 if (unlikely(group_stop)) {
1909 read_lock(&tasklist_lock);
1910 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1911 read_unlock(&tasklist_lock);
1915 EXPORT_SYMBOL(recalc_sigpending);
1916 EXPORT_SYMBOL_GPL(dequeue_signal);
1917 EXPORT_SYMBOL(flush_signals);
1918 EXPORT_SYMBOL(force_sig);
1919 EXPORT_SYMBOL(kill_proc);
1920 EXPORT_SYMBOL(ptrace_notify);
1921 EXPORT_SYMBOL(send_sig);
1922 EXPORT_SYMBOL(send_sig_info);
1923 EXPORT_SYMBOL(sigprocmask);
1924 EXPORT_SYMBOL(block_all_signals);
1925 EXPORT_SYMBOL(unblock_all_signals);
1929 * System call entry points.
1932 asmlinkage long sys_restart_syscall(void)
1934 struct restart_block *restart = ¤t_thread_info()->restart_block;
1935 return restart->fn(restart);
1938 long do_no_restart_syscall(struct restart_block *param)
1944 * We don't need to get the kernel lock - this is all local to this
1945 * particular thread.. (and that's good, because this is _heavily_
1946 * used by various programs)
1950 * This is also useful for kernel threads that want to temporarily
1951 * (or permanently) block certain signals.
1953 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1954 * interface happily blocks "unblockable" signals like SIGKILL
1957 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1961 spin_lock_irq(¤t->sighand->siglock);
1963 *oldset = current->blocked;
1968 sigorsets(¤t->blocked, ¤t->blocked, set);
1971 signandsets(¤t->blocked, ¤t->blocked, set);
1974 current->blocked = *set;
1979 recalc_sigpending();
1980 spin_unlock_irq(¤t->sighand->siglock);
1986 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1988 int error = -EINVAL;
1989 sigset_t old_set, new_set;
1991 /* XXX: Don't preclude handling different sized sigset_t's. */
1992 if (sigsetsize != sizeof(sigset_t))
1997 if (copy_from_user(&new_set, set, sizeof(*set)))
1999 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2001 error = sigprocmask(how, &new_set, &old_set);
2007 spin_lock_irq(¤t->sighand->siglock);
2008 old_set = current->blocked;
2009 spin_unlock_irq(¤t->sighand->siglock);
2013 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2021 long do_sigpending(void __user *set, unsigned long sigsetsize)
2023 long error = -EINVAL;
2026 if (sigsetsize > sizeof(sigset_t))
2029 spin_lock_irq(¤t->sighand->siglock);
2030 sigorsets(&pending, ¤t->pending.signal,
2031 ¤t->signal->shared_pending.signal);
2032 spin_unlock_irq(¤t->sighand->siglock);
2034 /* Outside the lock because only this thread touches it. */
2035 sigandsets(&pending, ¤t->blocked, &pending);
2038 if (!copy_to_user(set, &pending, sigsetsize))
2046 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2048 return do_sigpending(set, sigsetsize);
2051 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2053 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2057 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2059 if (from->si_code < 0)
2060 return __copy_to_user(to, from, sizeof(siginfo_t))
2063 * If you change siginfo_t structure, please be sure
2064 * this code is fixed accordingly.
2065 * Please remember to update the signalfd_copyinfo() function
2066 * inside fs/signalfd.c too, in case siginfo_t changes.
2067 * It should never copy any pad contained in the structure
2068 * to avoid security leaks, but must copy the generic
2069 * 3 ints plus the relevant union member.
2071 err = __put_user(from->si_signo, &to->si_signo);
2072 err |= __put_user(from->si_errno, &to->si_errno);
2073 err |= __put_user((short)from->si_code, &to->si_code);
2074 switch (from->si_code & __SI_MASK) {
2076 err |= __put_user(from->si_pid, &to->si_pid);
2077 err |= __put_user(from->si_uid, &to->si_uid);
2080 err |= __put_user(from->si_tid, &to->si_tid);
2081 err |= __put_user(from->si_overrun, &to->si_overrun);
2082 err |= __put_user(from->si_ptr, &to->si_ptr);
2085 err |= __put_user(from->si_band, &to->si_band);
2086 err |= __put_user(from->si_fd, &to->si_fd);
2089 err |= __put_user(from->si_addr, &to->si_addr);
2090 #ifdef __ARCH_SI_TRAPNO
2091 err |= __put_user(from->si_trapno, &to->si_trapno);
2095 err |= __put_user(from->si_pid, &to->si_pid);
2096 err |= __put_user(from->si_uid, &to->si_uid);
2097 err |= __put_user(from->si_status, &to->si_status);
2098 err |= __put_user(from->si_utime, &to->si_utime);
2099 err |= __put_user(from->si_stime, &to->si_stime);
2101 case __SI_RT: /* This is not generated by the kernel as of now. */
2102 case __SI_MESGQ: /* But this is */
2103 err |= __put_user(from->si_pid, &to->si_pid);
2104 err |= __put_user(from->si_uid, &to->si_uid);
2105 err |= __put_user(from->si_ptr, &to->si_ptr);
2107 default: /* this is just in case for now ... */
2108 err |= __put_user(from->si_pid, &to->si_pid);
2109 err |= __put_user(from->si_uid, &to->si_uid);
2118 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2119 siginfo_t __user *uinfo,
2120 const struct timespec __user *uts,
2129 /* XXX: Don't preclude handling different sized sigset_t's. */
2130 if (sigsetsize != sizeof(sigset_t))
2133 if (copy_from_user(&these, uthese, sizeof(these)))
2137 * Invert the set of allowed signals to get those we
2140 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2144 if (copy_from_user(&ts, uts, sizeof(ts)))
2146 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2151 spin_lock_irq(¤t->sighand->siglock);
2152 sig = dequeue_signal(current, &these, &info);
2154 timeout = MAX_SCHEDULE_TIMEOUT;
2156 timeout = (timespec_to_jiffies(&ts)
2157 + (ts.tv_sec || ts.tv_nsec));
2160 /* None ready -- temporarily unblock those we're
2161 * interested while we are sleeping in so that we'll
2162 * be awakened when they arrive. */
2163 current->real_blocked = current->blocked;
2164 sigandsets(¤t->blocked, ¤t->blocked, &these);
2165 recalc_sigpending();
2166 spin_unlock_irq(¤t->sighand->siglock);
2168 timeout = schedule_timeout_interruptible(timeout);
2170 spin_lock_irq(¤t->sighand->siglock);
2171 sig = dequeue_signal(current, &these, &info);
2172 current->blocked = current->real_blocked;
2173 siginitset(¤t->real_blocked, 0);
2174 recalc_sigpending();
2177 spin_unlock_irq(¤t->sighand->siglock);
2182 if (copy_siginfo_to_user(uinfo, &info))
2195 sys_kill(int pid, int sig)
2197 struct siginfo info;
2199 info.si_signo = sig;
2201 info.si_code = SI_USER;
2202 info.si_pid = task_tgid_vnr(current);
2203 info.si_uid = current->uid;
2205 return kill_something_info(sig, &info, pid);
2208 static int do_tkill(int tgid, int pid, int sig)
2211 struct siginfo info;
2212 struct task_struct *p;
2213 unsigned long flags;
2216 info.si_signo = sig;
2218 info.si_code = SI_TKILL;
2219 info.si_pid = task_tgid_vnr(current);
2220 info.si_uid = current->uid;
2223 p = find_task_by_vpid(pid);
2224 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2225 error = check_kill_permission(sig, &info, p);
2227 * The null signal is a permissions and process existence
2228 * probe. No signal is actually delivered.
2230 * If lock_task_sighand() fails we pretend the task dies
2231 * after receiving the signal. The window is tiny, and the
2232 * signal is private anyway.
2234 if (!error && sig && lock_task_sighand(p, &flags)) {
2235 error = specific_send_sig_info(sig, &info, p);
2236 unlock_task_sighand(p, &flags);
2245 * sys_tgkill - send signal to one specific thread
2246 * @tgid: the thread group ID of the thread
2247 * @pid: the PID of the thread
2248 * @sig: signal to be sent
2250 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2251 * exists but it's not belonging to the target process anymore. This
2252 * method solves the problem of threads exiting and PIDs getting reused.
2254 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2256 /* This is only valid for single tasks */
2257 if (pid <= 0 || tgid <= 0)
2260 return do_tkill(tgid, pid, sig);
2264 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2267 sys_tkill(int pid, int sig)
2269 /* This is only valid for single tasks */
2273 return do_tkill(0, pid, sig);
2277 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2281 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2284 /* Not even root can pretend to send signals from the kernel.
2285 Nor can they impersonate a kill(), which adds source info. */
2286 if (info.si_code >= 0)
2288 info.si_signo = sig;
2290 /* POSIX.1b doesn't mention process groups. */
2291 return kill_proc_info(sig, &info, pid);
2294 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2296 struct task_struct *t = current;
2297 struct k_sigaction *k;
2300 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2303 k = &t->sighand->action[sig-1];
2305 spin_lock_irq(¤t->sighand->siglock);
2310 sigdelsetmask(&act->sa.sa_mask,
2311 sigmask(SIGKILL) | sigmask(SIGSTOP));
2315 * "Setting a signal action to SIG_IGN for a signal that is
2316 * pending shall cause the pending signal to be discarded,
2317 * whether or not it is blocked."
2319 * "Setting a signal action to SIG_DFL for a signal that is
2320 * pending and whose default action is to ignore the signal
2321 * (for example, SIGCHLD), shall cause the pending signal to
2322 * be discarded, whether or not it is blocked"
2324 if (__sig_ignored(t, sig)) {
2326 sigaddset(&mask, sig);
2327 rm_from_queue_full(&mask, &t->signal->shared_pending);
2329 rm_from_queue_full(&mask, &t->pending);
2331 } while (t != current);
2335 spin_unlock_irq(¤t->sighand->siglock);
2340 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2346 oss.ss_sp = (void __user *) current->sas_ss_sp;
2347 oss.ss_size = current->sas_ss_size;
2348 oss.ss_flags = sas_ss_flags(sp);
2357 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2358 || __get_user(ss_sp, &uss->ss_sp)
2359 || __get_user(ss_flags, &uss->ss_flags)
2360 || __get_user(ss_size, &uss->ss_size))
2364 if (on_sig_stack(sp))
2370 * Note - this code used to test ss_flags incorrectly
2371 * old code may have been written using ss_flags==0
2372 * to mean ss_flags==SS_ONSTACK (as this was the only
2373 * way that worked) - this fix preserves that older
2376 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2379 if (ss_flags == SS_DISABLE) {
2384 if (ss_size < MINSIGSTKSZ)
2388 current->sas_ss_sp = (unsigned long) ss_sp;
2389 current->sas_ss_size = ss_size;
2394 if (copy_to_user(uoss, &oss, sizeof(oss)))
2403 #ifdef __ARCH_WANT_SYS_SIGPENDING
2406 sys_sigpending(old_sigset_t __user *set)
2408 return do_sigpending(set, sizeof(*set));
2413 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2414 /* Some platforms have their own version with special arguments others
2415 support only sys_rt_sigprocmask. */
2418 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2421 old_sigset_t old_set, new_set;
2425 if (copy_from_user(&new_set, set, sizeof(*set)))
2427 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2429 spin_lock_irq(¤t->sighand->siglock);
2430 old_set = current->blocked.sig[0];
2438 sigaddsetmask(¤t->blocked, new_set);
2441 sigdelsetmask(¤t->blocked, new_set);
2444 current->blocked.sig[0] = new_set;
2448 recalc_sigpending();
2449 spin_unlock_irq(¤t->sighand->siglock);
2455 old_set = current->blocked.sig[0];
2458 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2465 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2467 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2469 sys_rt_sigaction(int sig,
2470 const struct sigaction __user *act,
2471 struct sigaction __user *oact,
2474 struct k_sigaction new_sa, old_sa;
2477 /* XXX: Don't preclude handling different sized sigset_t's. */
2478 if (sigsetsize != sizeof(sigset_t))
2482 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2486 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2489 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2495 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2497 #ifdef __ARCH_WANT_SYS_SGETMASK
2500 * For backwards compatibility. Functionality superseded by sigprocmask.
2506 return current->blocked.sig[0];
2510 sys_ssetmask(int newmask)
2514 spin_lock_irq(¤t->sighand->siglock);
2515 old = current->blocked.sig[0];
2517 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2519 recalc_sigpending();
2520 spin_unlock_irq(¤t->sighand->siglock);
2524 #endif /* __ARCH_WANT_SGETMASK */
2526 #ifdef __ARCH_WANT_SYS_SIGNAL
2528 * For backwards compatibility. Functionality superseded by sigaction.
2530 asmlinkage unsigned long
2531 sys_signal(int sig, __sighandler_t handler)
2533 struct k_sigaction new_sa, old_sa;
2536 new_sa.sa.sa_handler = handler;
2537 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2538 sigemptyset(&new_sa.sa.sa_mask);
2540 ret = do_sigaction(sig, &new_sa, &old_sa);
2542 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2544 #endif /* __ARCH_WANT_SYS_SIGNAL */
2546 #ifdef __ARCH_WANT_SYS_PAUSE
2551 current->state = TASK_INTERRUPTIBLE;
2553 return -ERESTARTNOHAND;
2558 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2559 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2563 /* XXX: Don't preclude handling different sized sigset_t's. */
2564 if (sigsetsize != sizeof(sigset_t))
2567 if (copy_from_user(&newset, unewset, sizeof(newset)))
2569 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2571 spin_lock_irq(¤t->sighand->siglock);
2572 current->saved_sigmask = current->blocked;
2573 current->blocked = newset;
2574 recalc_sigpending();
2575 spin_unlock_irq(¤t->sighand->siglock);
2577 current->state = TASK_INTERRUPTIBLE;
2579 set_thread_flag(TIF_RESTORE_SIGMASK);
2580 return -ERESTARTNOHAND;
2582 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2584 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2589 void __init signals_init(void)
2591 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);