2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/tracehook.h>
26 #include <linux/capability.h>
27 #include <linux/freezer.h>
28 #include <linux/pid_namespace.h>
29 #include <linux/nsproxy.h>
31 #include <asm/param.h>
32 #include <asm/uaccess.h>
33 #include <asm/unistd.h>
34 #include <asm/siginfo.h>
35 #include "audit.h" /* audit_signal_info() */
38 * SLAB caches for signal bits.
41 static struct kmem_cache *sigqueue_cachep;
43 static void __user *sig_handler(struct task_struct *t, int sig)
45 return t->sighand->action[sig - 1].sa.sa_handler;
48 static int sig_handler_ignored(void __user *handler, int sig)
50 /* Is it explicitly or implicitly ignored? */
51 return handler == SIG_IGN ||
52 (handler == SIG_DFL && sig_kernel_ignore(sig));
55 static int sig_ignored(struct task_struct *t, int sig)
60 * Blocked signals are never ignored, since the
61 * signal handler may change by the time it is
64 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
67 handler = sig_handler(t, sig);
68 if (!sig_handler_ignored(handler, sig))
72 * Tracers may want to know about even ignored signals.
74 return !tracehook_consider_ignored_signal(t, sig, handler);
78 * Re-calculate pending state from the set of locally pending
79 * signals, globally pending signals, and blocked signals.
81 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
86 switch (_NSIG_WORDS) {
88 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
89 ready |= signal->sig[i] &~ blocked->sig[i];
92 case 4: ready = signal->sig[3] &~ blocked->sig[3];
93 ready |= signal->sig[2] &~ blocked->sig[2];
94 ready |= signal->sig[1] &~ blocked->sig[1];
95 ready |= signal->sig[0] &~ blocked->sig[0];
98 case 2: ready = signal->sig[1] &~ blocked->sig[1];
99 ready |= signal->sig[0] &~ blocked->sig[0];
102 case 1: ready = signal->sig[0] &~ blocked->sig[0];
107 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
109 static int recalc_sigpending_tsk(struct task_struct *t)
111 if (t->signal->group_stop_count > 0 ||
112 PENDING(&t->pending, &t->blocked) ||
113 PENDING(&t->signal->shared_pending, &t->blocked)) {
114 set_tsk_thread_flag(t, TIF_SIGPENDING);
118 * We must never clear the flag in another thread, or in current
119 * when it's possible the current syscall is returning -ERESTART*.
120 * So we don't clear it here, and only callers who know they should do.
126 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
127 * This is superfluous when called on current, the wakeup is a harmless no-op.
129 void recalc_sigpending_and_wake(struct task_struct *t)
131 if (recalc_sigpending_tsk(t))
132 signal_wake_up(t, 0);
135 void recalc_sigpending(void)
137 if (!recalc_sigpending_tsk(current) && !freezing(current))
138 clear_thread_flag(TIF_SIGPENDING);
142 /* Given the mask, find the first available signal that should be serviced. */
144 int next_signal(struct sigpending *pending, sigset_t *mask)
146 unsigned long i, *s, *m, x;
149 s = pending->signal.sig;
151 switch (_NSIG_WORDS) {
153 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
154 if ((x = *s &~ *m) != 0) {
155 sig = ffz(~x) + i*_NSIG_BPW + 1;
160 case 2: if ((x = s[0] &~ m[0]) != 0)
162 else if ((x = s[1] &~ m[1]) != 0)
169 case 1: if ((x = *s &~ *m) != 0)
177 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
180 struct sigqueue *q = NULL;
181 struct user_struct *user;
184 * In order to avoid problems with "switch_user()", we want to make
185 * sure that the compiler doesn't re-load "t->user"
189 atomic_inc(&user->sigpending);
190 if (override_rlimit ||
191 atomic_read(&user->sigpending) <=
192 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
193 q = kmem_cache_alloc(sigqueue_cachep, flags);
194 if (unlikely(q == NULL)) {
195 atomic_dec(&user->sigpending);
197 INIT_LIST_HEAD(&q->list);
199 q->user = get_uid(user);
204 static void __sigqueue_free(struct sigqueue *q)
206 if (q->flags & SIGQUEUE_PREALLOC)
208 atomic_dec(&q->user->sigpending);
210 kmem_cache_free(sigqueue_cachep, q);
213 void flush_sigqueue(struct sigpending *queue)
217 sigemptyset(&queue->signal);
218 while (!list_empty(&queue->list)) {
219 q = list_entry(queue->list.next, struct sigqueue , list);
220 list_del_init(&q->list);
226 * Flush all pending signals for a task.
228 void flush_signals(struct task_struct *t)
232 spin_lock_irqsave(&t->sighand->siglock, flags);
233 clear_tsk_thread_flag(t, TIF_SIGPENDING);
234 flush_sigqueue(&t->pending);
235 flush_sigqueue(&t->signal->shared_pending);
236 spin_unlock_irqrestore(&t->sighand->siglock, flags);
239 static void __flush_itimer_signals(struct sigpending *pending)
241 sigset_t signal, retain;
242 struct sigqueue *q, *n;
244 signal = pending->signal;
245 sigemptyset(&retain);
247 list_for_each_entry_safe(q, n, &pending->list, list) {
248 int sig = q->info.si_signo;
250 if (likely(q->info.si_code != SI_TIMER)) {
251 sigaddset(&retain, sig);
253 sigdelset(&signal, sig);
254 list_del_init(&q->list);
259 sigorsets(&pending->signal, &signal, &retain);
262 void flush_itimer_signals(void)
264 struct task_struct *tsk = current;
267 spin_lock_irqsave(&tsk->sighand->siglock, flags);
268 __flush_itimer_signals(&tsk->pending);
269 __flush_itimer_signals(&tsk->signal->shared_pending);
270 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
273 void ignore_signals(struct task_struct *t)
277 for (i = 0; i < _NSIG; ++i)
278 t->sighand->action[i].sa.sa_handler = SIG_IGN;
284 * Flush all handlers for a task.
288 flush_signal_handlers(struct task_struct *t, int force_default)
291 struct k_sigaction *ka = &t->sighand->action[0];
292 for (i = _NSIG ; i != 0 ; i--) {
293 if (force_default || ka->sa.sa_handler != SIG_IGN)
294 ka->sa.sa_handler = SIG_DFL;
296 sigemptyset(&ka->sa.sa_mask);
301 int unhandled_signal(struct task_struct *tsk, int sig)
303 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
304 if (is_global_init(tsk))
306 if (handler != SIG_IGN && handler != SIG_DFL)
308 return !tracehook_consider_fatal_signal(tsk, sig, handler);
312 /* Notify the system that a driver wants to block all signals for this
313 * process, and wants to be notified if any signals at all were to be
314 * sent/acted upon. If the notifier routine returns non-zero, then the
315 * signal will be acted upon after all. If the notifier routine returns 0,
316 * then then signal will be blocked. Only one block per process is
317 * allowed. priv is a pointer to private data that the notifier routine
318 * can use to determine if the signal should be blocked or not. */
321 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
325 spin_lock_irqsave(¤t->sighand->siglock, flags);
326 current->notifier_mask = mask;
327 current->notifier_data = priv;
328 current->notifier = notifier;
329 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
332 /* Notify the system that blocking has ended. */
335 unblock_all_signals(void)
339 spin_lock_irqsave(¤t->sighand->siglock, flags);
340 current->notifier = NULL;
341 current->notifier_data = NULL;
343 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
346 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
348 struct sigqueue *q, *first = NULL;
351 * Collect the siginfo appropriate to this signal. Check if
352 * there is another siginfo for the same signal.
354 list_for_each_entry(q, &list->list, list) {
355 if (q->info.si_signo == sig) {
362 sigdelset(&list->signal, sig);
366 list_del_init(&first->list);
367 copy_siginfo(info, &first->info);
368 __sigqueue_free(first);
370 /* Ok, it wasn't in the queue. This must be
371 a fast-pathed signal or we must have been
372 out of queue space. So zero out the info.
374 info->si_signo = sig;
382 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
385 int sig = next_signal(pending, mask);
388 if (current->notifier) {
389 if (sigismember(current->notifier_mask, sig)) {
390 if (!(current->notifier)(current->notifier_data)) {
391 clear_thread_flag(TIF_SIGPENDING);
397 collect_signal(sig, pending, info);
404 * Dequeue a signal and return the element to the caller, which is
405 * expected to free it.
407 * All callers have to hold the siglock.
409 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
413 /* We only dequeue private signals from ourselves, we don't let
414 * signalfd steal them
416 signr = __dequeue_signal(&tsk->pending, mask, info);
418 signr = __dequeue_signal(&tsk->signal->shared_pending,
423 * itimers are process shared and we restart periodic
424 * itimers in the signal delivery path to prevent DoS
425 * attacks in the high resolution timer case. This is
426 * compliant with the old way of self restarting
427 * itimers, as the SIGALRM is a legacy signal and only
428 * queued once. Changing the restart behaviour to
429 * restart the timer in the signal dequeue path is
430 * reducing the timer noise on heavy loaded !highres
433 if (unlikely(signr == SIGALRM)) {
434 struct hrtimer *tmr = &tsk->signal->real_timer;
436 if (!hrtimer_is_queued(tmr) &&
437 tsk->signal->it_real_incr.tv64 != 0) {
438 hrtimer_forward(tmr, tmr->base->get_time(),
439 tsk->signal->it_real_incr);
440 hrtimer_restart(tmr);
449 if (unlikely(sig_kernel_stop(signr))) {
451 * Set a marker that we have dequeued a stop signal. Our
452 * caller might release the siglock and then the pending
453 * stop signal it is about to process is no longer in the
454 * pending bitmasks, but must still be cleared by a SIGCONT
455 * (and overruled by a SIGKILL). So those cases clear this
456 * shared flag after we've set it. Note that this flag may
457 * remain set after the signal we return is ignored or
458 * handled. That doesn't matter because its only purpose
459 * is to alert stop-signal processing code when another
460 * processor has come along and cleared the flag.
462 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
464 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
466 * Release the siglock to ensure proper locking order
467 * of timer locks outside of siglocks. Note, we leave
468 * irqs disabled here, since the posix-timers code is
469 * about to disable them again anyway.
471 spin_unlock(&tsk->sighand->siglock);
472 do_schedule_next_timer(info);
473 spin_lock(&tsk->sighand->siglock);
479 * Tell a process that it has a new active signal..
481 * NOTE! we rely on the previous spin_lock to
482 * lock interrupts for us! We can only be called with
483 * "siglock" held, and the local interrupt must
484 * have been disabled when that got acquired!
486 * No need to set need_resched since signal event passing
487 * goes through ->blocked
489 void signal_wake_up(struct task_struct *t, int resume)
493 set_tsk_thread_flag(t, TIF_SIGPENDING);
496 * For SIGKILL, we want to wake it up in the stopped/traced/killable
497 * case. We don't check t->state here because there is a race with it
498 * executing another processor and just now entering stopped state.
499 * By using wake_up_state, we ensure the process will wake up and
500 * handle its death signal.
502 mask = TASK_INTERRUPTIBLE;
504 mask |= TASK_WAKEKILL;
505 if (!wake_up_state(t, mask))
510 * Remove signals in mask from the pending set and queue.
511 * Returns 1 if any signals were found.
513 * All callers must be holding the siglock.
515 * This version takes a sigset mask and looks at all signals,
516 * not just those in the first mask word.
518 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
520 struct sigqueue *q, *n;
523 sigandsets(&m, mask, &s->signal);
524 if (sigisemptyset(&m))
527 signandsets(&s->signal, &s->signal, mask);
528 list_for_each_entry_safe(q, n, &s->list, list) {
529 if (sigismember(mask, q->info.si_signo)) {
530 list_del_init(&q->list);
537 * Remove signals in mask from the pending set and queue.
538 * Returns 1 if any signals were found.
540 * All callers must be holding the siglock.
542 static int rm_from_queue(unsigned long mask, struct sigpending *s)
544 struct sigqueue *q, *n;
546 if (!sigtestsetmask(&s->signal, mask))
549 sigdelsetmask(&s->signal, mask);
550 list_for_each_entry_safe(q, n, &s->list, list) {
551 if (q->info.si_signo < SIGRTMIN &&
552 (mask & sigmask(q->info.si_signo))) {
553 list_del_init(&q->list);
561 * Bad permissions for sending the signal
563 static int check_kill_permission(int sig, struct siginfo *info,
564 struct task_struct *t)
569 if (!valid_signal(sig))
572 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
575 error = audit_signal_info(sig, t); /* Let audit system see the signal */
579 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
580 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
581 !capable(CAP_KILL)) {
584 sid = task_session(t);
586 * We don't return the error if sid == NULL. The
587 * task was unhashed, the caller must notice this.
589 if (!sid || sid == task_session(current))
596 return security_task_kill(t, info, sig, 0);
600 * Handle magic process-wide effects of stop/continue signals. Unlike
601 * the signal actions, these happen immediately at signal-generation
602 * time regardless of blocking, ignoring, or handling. This does the
603 * actual continuing for SIGCONT, but not the actual stopping for stop
604 * signals. The process stop is done as a signal action for SIG_DFL.
606 * Returns true if the signal should be actually delivered, otherwise
607 * it should be dropped.
609 static int prepare_signal(int sig, struct task_struct *p)
611 struct signal_struct *signal = p->signal;
612 struct task_struct *t;
614 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
616 * The process is in the middle of dying, nothing to do.
618 } else if (sig_kernel_stop(sig)) {
620 * This is a stop signal. Remove SIGCONT from all queues.
622 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
625 rm_from_queue(sigmask(SIGCONT), &t->pending);
626 } while_each_thread(p, t);
627 } else if (sig == SIGCONT) {
630 * Remove all stop signals from all queues,
631 * and wake all threads.
633 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
637 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
639 * If there is a handler for SIGCONT, we must make
640 * sure that no thread returns to user mode before
641 * we post the signal, in case it was the only
642 * thread eligible to run the signal handler--then
643 * it must not do anything between resuming and
644 * running the handler. With the TIF_SIGPENDING
645 * flag set, the thread will pause and acquire the
646 * siglock that we hold now and until we've queued
647 * the pending signal.
649 * Wake up the stopped thread _after_ setting
652 state = __TASK_STOPPED;
653 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
654 set_tsk_thread_flag(t, TIF_SIGPENDING);
655 state |= TASK_INTERRUPTIBLE;
657 wake_up_state(t, state);
658 } while_each_thread(p, t);
661 * Notify the parent with CLD_CONTINUED if we were stopped.
663 * If we were in the middle of a group stop, we pretend it
664 * was already finished, and then continued. Since SIGCHLD
665 * doesn't queue we report only CLD_STOPPED, as if the next
666 * CLD_CONTINUED was dropped.
669 if (signal->flags & SIGNAL_STOP_STOPPED)
670 why |= SIGNAL_CLD_CONTINUED;
671 else if (signal->group_stop_count)
672 why |= SIGNAL_CLD_STOPPED;
676 * The first thread which returns from finish_stop()
677 * will take ->siglock, notice SIGNAL_CLD_MASK, and
678 * notify its parent. See get_signal_to_deliver().
680 signal->flags = why | SIGNAL_STOP_CONTINUED;
681 signal->group_stop_count = 0;
682 signal->group_exit_code = 0;
685 * We are not stopped, but there could be a stop
686 * signal in the middle of being processed after
687 * being removed from the queue. Clear that too.
689 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
693 return !sig_ignored(p, sig);
697 * Test if P wants to take SIG. After we've checked all threads with this,
698 * it's equivalent to finding no threads not blocking SIG. Any threads not
699 * blocking SIG were ruled out because they are not running and already
700 * have pending signals. Such threads will dequeue from the shared queue
701 * as soon as they're available, so putting the signal on the shared queue
702 * will be equivalent to sending it to one such thread.
704 static inline int wants_signal(int sig, struct task_struct *p)
706 if (sigismember(&p->blocked, sig))
708 if (p->flags & PF_EXITING)
712 if (task_is_stopped_or_traced(p))
714 return task_curr(p) || !signal_pending(p);
717 static void complete_signal(int sig, struct task_struct *p, int group)
719 struct signal_struct *signal = p->signal;
720 struct task_struct *t;
723 * Now find a thread we can wake up to take the signal off the queue.
725 * If the main thread wants the signal, it gets first crack.
726 * Probably the least surprising to the average bear.
728 if (wants_signal(sig, p))
730 else if (!group || thread_group_empty(p))
732 * There is just one thread and it does not need to be woken.
733 * It will dequeue unblocked signals before it runs again.
738 * Otherwise try to find a suitable thread.
740 t = signal->curr_target;
741 while (!wants_signal(sig, t)) {
743 if (t == signal->curr_target)
745 * No thread needs to be woken.
746 * Any eligible threads will see
747 * the signal in the queue soon.
751 signal->curr_target = t;
755 * Found a killable thread. If the signal will be fatal,
756 * then start taking the whole group down immediately.
758 if (sig_fatal(p, sig) &&
759 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
760 !sigismember(&t->real_blocked, sig) &&
762 !tracehook_consider_fatal_signal(t, sig, SIG_DFL))) {
764 * This signal will be fatal to the whole group.
766 if (!sig_kernel_coredump(sig)) {
768 * Start a group exit and wake everybody up.
769 * This way we don't have other threads
770 * running and doing things after a slower
771 * thread has the fatal signal pending.
773 signal->flags = SIGNAL_GROUP_EXIT;
774 signal->group_exit_code = sig;
775 signal->group_stop_count = 0;
778 sigaddset(&t->pending.signal, SIGKILL);
779 signal_wake_up(t, 1);
780 } while_each_thread(p, t);
786 * The signal is already in the shared-pending queue.
787 * Tell the chosen thread to wake up and dequeue it.
789 signal_wake_up(t, sig == SIGKILL);
793 static inline int legacy_queue(struct sigpending *signals, int sig)
795 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
798 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
801 struct sigpending *pending;
804 assert_spin_locked(&t->sighand->siglock);
805 if (!prepare_signal(sig, t))
808 pending = group ? &t->signal->shared_pending : &t->pending;
810 * Short-circuit ignored signals and support queuing
811 * exactly one non-rt signal, so that we can get more
812 * detailed information about the cause of the signal.
814 if (legacy_queue(pending, sig))
817 * fast-pathed signals for kernel-internal things like SIGSTOP
820 if (info == SEND_SIG_FORCED)
823 /* Real-time signals must be queued if sent by sigqueue, or
824 some other real-time mechanism. It is implementation
825 defined whether kill() does so. We attempt to do so, on
826 the principle of least surprise, but since kill is not
827 allowed to fail with EAGAIN when low on memory we just
828 make sure at least one signal gets delivered and don't
829 pass on the info struct. */
831 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
832 (is_si_special(info) ||
833 info->si_code >= 0)));
835 list_add_tail(&q->list, &pending->list);
836 switch ((unsigned long) info) {
837 case (unsigned long) SEND_SIG_NOINFO:
838 q->info.si_signo = sig;
839 q->info.si_errno = 0;
840 q->info.si_code = SI_USER;
841 q->info.si_pid = task_pid_vnr(current);
842 q->info.si_uid = current->uid;
844 case (unsigned long) SEND_SIG_PRIV:
845 q->info.si_signo = sig;
846 q->info.si_errno = 0;
847 q->info.si_code = SI_KERNEL;
852 copy_siginfo(&q->info, info);
855 } else if (!is_si_special(info)) {
856 if (sig >= SIGRTMIN && info->si_code != SI_USER)
858 * Queue overflow, abort. We may abort if the signal was rt
859 * and sent by user using something other than kill().
865 signalfd_notify(t, sig);
866 sigaddset(&pending->signal, sig);
867 complete_signal(sig, t, group);
871 int print_fatal_signals;
873 static void print_fatal_signal(struct pt_regs *regs, int signr)
875 printk("%s/%d: potentially unexpected fatal signal %d.\n",
876 current->comm, task_pid_nr(current), signr);
878 #if defined(__i386__) && !defined(__arch_um__)
879 printk("code at %08lx: ", regs->ip);
882 for (i = 0; i < 16; i++) {
885 __get_user(insn, (unsigned char *)(regs->ip + i));
886 printk("%02x ", insn);
894 static int __init setup_print_fatal_signals(char *str)
896 get_option (&str, &print_fatal_signals);
901 __setup("print-fatal-signals=", setup_print_fatal_signals);
904 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
906 return send_signal(sig, info, p, 1);
910 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
912 return send_signal(sig, info, t, 0);
916 * Force a signal that the process can't ignore: if necessary
917 * we unblock the signal and change any SIG_IGN to SIG_DFL.
919 * Note: If we unblock the signal, we always reset it to SIG_DFL,
920 * since we do not want to have a signal handler that was blocked
921 * be invoked when user space had explicitly blocked it.
923 * We don't want to have recursive SIGSEGV's etc, for example,
924 * that is why we also clear SIGNAL_UNKILLABLE.
927 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
929 unsigned long int flags;
930 int ret, blocked, ignored;
931 struct k_sigaction *action;
933 spin_lock_irqsave(&t->sighand->siglock, flags);
934 action = &t->sighand->action[sig-1];
935 ignored = action->sa.sa_handler == SIG_IGN;
936 blocked = sigismember(&t->blocked, sig);
937 if (blocked || ignored) {
938 action->sa.sa_handler = SIG_DFL;
940 sigdelset(&t->blocked, sig);
941 recalc_sigpending_and_wake(t);
944 if (action->sa.sa_handler == SIG_DFL)
945 t->signal->flags &= ~SIGNAL_UNKILLABLE;
946 ret = specific_send_sig_info(sig, info, t);
947 spin_unlock_irqrestore(&t->sighand->siglock, flags);
953 force_sig_specific(int sig, struct task_struct *t)
955 force_sig_info(sig, SEND_SIG_FORCED, t);
959 * Nuke all other threads in the group.
961 void zap_other_threads(struct task_struct *p)
963 struct task_struct *t;
965 p->signal->group_stop_count = 0;
967 for (t = next_thread(p); t != p; t = next_thread(t)) {
969 * Don't bother with already dead threads
974 /* SIGKILL will be handled before any pending SIGSTOP */
975 sigaddset(&t->pending.signal, SIGKILL);
976 signal_wake_up(t, 1);
980 int __fatal_signal_pending(struct task_struct *tsk)
982 return sigismember(&tsk->pending.signal, SIGKILL);
984 EXPORT_SYMBOL(__fatal_signal_pending);
986 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
988 struct sighand_struct *sighand;
992 sighand = rcu_dereference(tsk->sighand);
993 if (unlikely(sighand == NULL))
996 spin_lock_irqsave(&sighand->siglock, *flags);
997 if (likely(sighand == tsk->sighand))
999 spin_unlock_irqrestore(&sighand->siglock, *flags);
1006 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1008 unsigned long flags;
1011 ret = check_kill_permission(sig, info, p);
1015 if (lock_task_sighand(p, &flags)) {
1016 ret = __group_send_sig_info(sig, info, p);
1017 unlock_task_sighand(p, &flags);
1025 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1026 * control characters do (^C, ^Z etc)
1029 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1031 struct task_struct *p = NULL;
1032 int retval, success;
1036 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1037 int err = group_send_sig_info(sig, info, p);
1040 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1041 return success ? 0 : retval;
1044 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1047 struct task_struct *p;
1051 p = pid_task(pid, PIDTYPE_PID);
1053 error = group_send_sig_info(sig, info, p);
1054 if (unlikely(error == -ESRCH))
1056 * The task was unhashed in between, try again.
1057 * If it is dead, pid_task() will return NULL,
1058 * if we race with de_thread() it will find the
1069 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1073 error = kill_pid_info(sig, info, find_vpid(pid));
1078 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1079 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1080 uid_t uid, uid_t euid, u32 secid)
1083 struct task_struct *p;
1085 if (!valid_signal(sig))
1088 read_lock(&tasklist_lock);
1089 p = pid_task(pid, PIDTYPE_PID);
1094 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1095 && (euid != p->suid) && (euid != p->uid)
1096 && (uid != p->suid) && (uid != p->uid)) {
1100 ret = security_task_kill(p, info, sig, secid);
1103 if (sig && p->sighand) {
1104 unsigned long flags;
1105 spin_lock_irqsave(&p->sighand->siglock, flags);
1106 ret = __group_send_sig_info(sig, info, p);
1107 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1110 read_unlock(&tasklist_lock);
1113 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1116 * kill_something_info() interprets pid in interesting ways just like kill(2).
1118 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1119 * is probably wrong. Should make it like BSD or SYSV.
1122 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1128 ret = kill_pid_info(sig, info, find_vpid(pid));
1133 read_lock(&tasklist_lock);
1135 ret = __kill_pgrp_info(sig, info,
1136 pid ? find_vpid(-pid) : task_pgrp(current));
1138 int retval = 0, count = 0;
1139 struct task_struct * p;
1141 for_each_process(p) {
1142 if (p->pid > 1 && !same_thread_group(p, current)) {
1143 int err = group_send_sig_info(sig, info, p);
1149 ret = count ? retval : -ESRCH;
1151 read_unlock(&tasklist_lock);
1157 * These are for backward compatibility with the rest of the kernel source.
1161 * The caller must ensure the task can't exit.
1164 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1167 unsigned long flags;
1170 * Make sure legacy kernel users don't send in bad values
1171 * (normal paths check this in check_kill_permission).
1173 if (!valid_signal(sig))
1176 spin_lock_irqsave(&p->sighand->siglock, flags);
1177 ret = specific_send_sig_info(sig, info, p);
1178 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1182 #define __si_special(priv) \
1183 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1186 send_sig(int sig, struct task_struct *p, int priv)
1188 return send_sig_info(sig, __si_special(priv), p);
1192 force_sig(int sig, struct task_struct *p)
1194 force_sig_info(sig, SEND_SIG_PRIV, p);
1198 * When things go south during signal handling, we
1199 * will force a SIGSEGV. And if the signal that caused
1200 * the problem was already a SIGSEGV, we'll want to
1201 * make sure we don't even try to deliver the signal..
1204 force_sigsegv(int sig, struct task_struct *p)
1206 if (sig == SIGSEGV) {
1207 unsigned long flags;
1208 spin_lock_irqsave(&p->sighand->siglock, flags);
1209 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1210 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1212 force_sig(SIGSEGV, p);
1216 int kill_pgrp(struct pid *pid, int sig, int priv)
1220 read_lock(&tasklist_lock);
1221 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1222 read_unlock(&tasklist_lock);
1226 EXPORT_SYMBOL(kill_pgrp);
1228 int kill_pid(struct pid *pid, int sig, int priv)
1230 return kill_pid_info(sig, __si_special(priv), pid);
1232 EXPORT_SYMBOL(kill_pid);
1235 * These functions support sending signals using preallocated sigqueue
1236 * structures. This is needed "because realtime applications cannot
1237 * afford to lose notifications of asynchronous events, like timer
1238 * expirations or I/O completions". In the case of Posix Timers
1239 * we allocate the sigqueue structure from the timer_create. If this
1240 * allocation fails we are able to report the failure to the application
1241 * with an EAGAIN error.
1244 struct sigqueue *sigqueue_alloc(void)
1248 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1249 q->flags |= SIGQUEUE_PREALLOC;
1253 void sigqueue_free(struct sigqueue *q)
1255 unsigned long flags;
1256 spinlock_t *lock = ¤t->sighand->siglock;
1258 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1260 * We must hold ->siglock while testing q->list
1261 * to serialize with collect_signal() or with
1262 * __exit_signal()->flush_sigqueue().
1264 spin_lock_irqsave(lock, flags);
1265 q->flags &= ~SIGQUEUE_PREALLOC;
1267 * If it is queued it will be freed when dequeued,
1268 * like the "regular" sigqueue.
1270 if (!list_empty(&q->list))
1272 spin_unlock_irqrestore(lock, flags);
1278 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1280 int sig = q->info.si_signo;
1281 struct sigpending *pending;
1282 unsigned long flags;
1285 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1288 if (!likely(lock_task_sighand(t, &flags)))
1291 ret = 1; /* the signal is ignored */
1292 if (!prepare_signal(sig, t))
1296 if (unlikely(!list_empty(&q->list))) {
1298 * If an SI_TIMER entry is already queue just increment
1299 * the overrun count.
1301 BUG_ON(q->info.si_code != SI_TIMER);
1302 q->info.si_overrun++;
1306 signalfd_notify(t, sig);
1307 pending = group ? &t->signal->shared_pending : &t->pending;
1308 list_add_tail(&q->list, &pending->list);
1309 sigaddset(&pending->signal, sig);
1310 complete_signal(sig, t, group);
1312 unlock_task_sighand(t, &flags);
1318 * Wake up any threads in the parent blocked in wait* syscalls.
1320 static inline void __wake_up_parent(struct task_struct *p,
1321 struct task_struct *parent)
1323 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1327 * Let a parent know about the death of a child.
1328 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1330 * Returns -1 if our parent ignored us and so we've switched to
1331 * self-reaping, or else @sig.
1333 int do_notify_parent(struct task_struct *tsk, int sig)
1335 struct siginfo info;
1336 unsigned long flags;
1337 struct sighand_struct *psig;
1341 /* do_notify_parent_cldstop should have been called instead. */
1342 BUG_ON(task_is_stopped_or_traced(tsk));
1344 BUG_ON(!tsk->ptrace &&
1345 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1347 info.si_signo = sig;
1350 * we are under tasklist_lock here so our parent is tied to
1351 * us and cannot exit and release its namespace.
1353 * the only it can is to switch its nsproxy with sys_unshare,
1354 * bu uncharing pid namespaces is not allowed, so we'll always
1355 * see relevant namespace
1357 * write_lock() currently calls preempt_disable() which is the
1358 * same as rcu_read_lock(), but according to Oleg, this is not
1359 * correct to rely on this
1362 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1365 info.si_uid = tsk->uid;
1367 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1368 tsk->signal->utime));
1369 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1370 tsk->signal->stime));
1372 info.si_status = tsk->exit_code & 0x7f;
1373 if (tsk->exit_code & 0x80)
1374 info.si_code = CLD_DUMPED;
1375 else if (tsk->exit_code & 0x7f)
1376 info.si_code = CLD_KILLED;
1378 info.si_code = CLD_EXITED;
1379 info.si_status = tsk->exit_code >> 8;
1382 psig = tsk->parent->sighand;
1383 spin_lock_irqsave(&psig->siglock, flags);
1384 if (!tsk->ptrace && sig == SIGCHLD &&
1385 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1386 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1388 * We are exiting and our parent doesn't care. POSIX.1
1389 * defines special semantics for setting SIGCHLD to SIG_IGN
1390 * or setting the SA_NOCLDWAIT flag: we should be reaped
1391 * automatically and not left for our parent's wait4 call.
1392 * Rather than having the parent do it as a magic kind of
1393 * signal handler, we just set this to tell do_exit that we
1394 * can be cleaned up without becoming a zombie. Note that
1395 * we still call __wake_up_parent in this case, because a
1396 * blocked sys_wait4 might now return -ECHILD.
1398 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1399 * is implementation-defined: we do (if you don't want
1400 * it, just use SIG_IGN instead).
1402 tsk->exit_signal = -1;
1403 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1406 if (valid_signal(sig) && sig > 0)
1407 __group_send_sig_info(sig, &info, tsk->parent);
1408 __wake_up_parent(tsk, tsk->parent);
1409 spin_unlock_irqrestore(&psig->siglock, flags);
1414 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1416 struct siginfo info;
1417 unsigned long flags;
1418 struct task_struct *parent;
1419 struct sighand_struct *sighand;
1421 if (tsk->ptrace & PT_PTRACED)
1422 parent = tsk->parent;
1424 tsk = tsk->group_leader;
1425 parent = tsk->real_parent;
1428 info.si_signo = SIGCHLD;
1431 * see comment in do_notify_parent() abot the following 3 lines
1434 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1437 info.si_uid = tsk->uid;
1439 info.si_utime = cputime_to_clock_t(tsk->utime);
1440 info.si_stime = cputime_to_clock_t(tsk->stime);
1445 info.si_status = SIGCONT;
1448 info.si_status = tsk->signal->group_exit_code & 0x7f;
1451 info.si_status = tsk->exit_code & 0x7f;
1457 sighand = parent->sighand;
1458 spin_lock_irqsave(&sighand->siglock, flags);
1459 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1460 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1461 __group_send_sig_info(SIGCHLD, &info, parent);
1463 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1465 __wake_up_parent(tsk, parent);
1466 spin_unlock_irqrestore(&sighand->siglock, flags);
1469 static inline int may_ptrace_stop(void)
1471 if (!likely(current->ptrace & PT_PTRACED))
1474 * Are we in the middle of do_coredump?
1475 * If so and our tracer is also part of the coredump stopping
1476 * is a deadlock situation, and pointless because our tracer
1477 * is dead so don't allow us to stop.
1478 * If SIGKILL was already sent before the caller unlocked
1479 * ->siglock we must see ->core_state != NULL. Otherwise it
1480 * is safe to enter schedule().
1482 if (unlikely(current->mm->core_state) &&
1483 unlikely(current->mm == current->parent->mm))
1490 * Return nonzero if there is a SIGKILL that should be waking us up.
1491 * Called with the siglock held.
1493 static int sigkill_pending(struct task_struct *tsk)
1495 return sigismember(&tsk->pending.signal, SIGKILL) ||
1496 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1500 * This must be called with current->sighand->siglock held.
1502 * This should be the path for all ptrace stops.
1503 * We always set current->last_siginfo while stopped here.
1504 * That makes it a way to test a stopped process for
1505 * being ptrace-stopped vs being job-control-stopped.
1507 * If we actually decide not to stop at all because the tracer
1508 * is gone, we keep current->exit_code unless clear_code.
1510 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1512 if (arch_ptrace_stop_needed(exit_code, info)) {
1514 * The arch code has something special to do before a
1515 * ptrace stop. This is allowed to block, e.g. for faults
1516 * on user stack pages. We can't keep the siglock while
1517 * calling arch_ptrace_stop, so we must release it now.
1518 * To preserve proper semantics, we must do this before
1519 * any signal bookkeeping like checking group_stop_count.
1520 * Meanwhile, a SIGKILL could come in before we retake the
1521 * siglock. That must prevent us from sleeping in TASK_TRACED.
1522 * So after regaining the lock, we must check for SIGKILL.
1524 spin_unlock_irq(¤t->sighand->siglock);
1525 arch_ptrace_stop(exit_code, info);
1526 spin_lock_irq(¤t->sighand->siglock);
1527 if (sigkill_pending(current))
1532 * If there is a group stop in progress,
1533 * we must participate in the bookkeeping.
1535 if (current->signal->group_stop_count > 0)
1536 --current->signal->group_stop_count;
1538 current->last_siginfo = info;
1539 current->exit_code = exit_code;
1541 /* Let the debugger run. */
1542 __set_current_state(TASK_TRACED);
1543 spin_unlock_irq(¤t->sighand->siglock);
1544 read_lock(&tasklist_lock);
1545 if (may_ptrace_stop()) {
1546 do_notify_parent_cldstop(current, CLD_TRAPPED);
1547 read_unlock(&tasklist_lock);
1551 * By the time we got the lock, our tracer went away.
1552 * Don't drop the lock yet, another tracer may come.
1554 __set_current_state(TASK_RUNNING);
1556 current->exit_code = 0;
1557 read_unlock(&tasklist_lock);
1561 * While in TASK_TRACED, we were considered "frozen enough".
1562 * Now that we woke up, it's crucial if we're supposed to be
1563 * frozen that we freeze now before running anything substantial.
1568 * We are back. Now reacquire the siglock before touching
1569 * last_siginfo, so that we are sure to have synchronized with
1570 * any signal-sending on another CPU that wants to examine it.
1572 spin_lock_irq(¤t->sighand->siglock);
1573 current->last_siginfo = NULL;
1576 * Queued signals ignored us while we were stopped for tracing.
1577 * So check for any that we should take before resuming user mode.
1578 * This sets TIF_SIGPENDING, but never clears it.
1580 recalc_sigpending_tsk(current);
1583 void ptrace_notify(int exit_code)
1587 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1589 memset(&info, 0, sizeof info);
1590 info.si_signo = SIGTRAP;
1591 info.si_code = exit_code;
1592 info.si_pid = task_pid_vnr(current);
1593 info.si_uid = current->uid;
1595 /* Let the debugger run. */
1596 spin_lock_irq(¤t->sighand->siglock);
1597 ptrace_stop(exit_code, 1, &info);
1598 spin_unlock_irq(¤t->sighand->siglock);
1602 finish_stop(int stop_count)
1605 * If there are no other threads in the group, or if there is
1606 * a group stop in progress and we are the last to stop,
1607 * report to the parent. When ptraced, every thread reports itself.
1609 if (tracehook_notify_jctl(stop_count == 0, CLD_STOPPED)) {
1610 read_lock(&tasklist_lock);
1611 do_notify_parent_cldstop(current, CLD_STOPPED);
1612 read_unlock(&tasklist_lock);
1617 } while (try_to_freeze());
1619 * Now we don't run again until continued.
1621 current->exit_code = 0;
1625 * This performs the stopping for SIGSTOP and other stop signals.
1626 * We have to stop all threads in the thread group.
1627 * Returns nonzero if we've actually stopped and released the siglock.
1628 * Returns zero if we didn't stop and still hold the siglock.
1630 static int do_signal_stop(int signr)
1632 struct signal_struct *sig = current->signal;
1635 if (sig->group_stop_count > 0) {
1637 * There is a group stop in progress. We don't need to
1638 * start another one.
1640 stop_count = --sig->group_stop_count;
1642 struct task_struct *t;
1644 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1645 unlikely(signal_group_exit(sig)))
1648 * There is no group stop already in progress.
1649 * We must initiate one now.
1651 sig->group_exit_code = signr;
1654 for (t = next_thread(current); t != current; t = next_thread(t))
1656 * Setting state to TASK_STOPPED for a group
1657 * stop is always done with the siglock held,
1658 * so this check has no races.
1660 if (!(t->flags & PF_EXITING) &&
1661 !task_is_stopped_or_traced(t)) {
1663 signal_wake_up(t, 0);
1665 sig->group_stop_count = stop_count;
1668 if (stop_count == 0)
1669 sig->flags = SIGNAL_STOP_STOPPED;
1670 current->exit_code = sig->group_exit_code;
1671 __set_current_state(TASK_STOPPED);
1673 spin_unlock_irq(¤t->sighand->siglock);
1674 finish_stop(stop_count);
1678 static int ptrace_signal(int signr, siginfo_t *info,
1679 struct pt_regs *regs, void *cookie)
1681 if (!(current->ptrace & PT_PTRACED))
1684 ptrace_signal_deliver(regs, cookie);
1686 /* Let the debugger run. */
1687 ptrace_stop(signr, 0, info);
1689 /* We're back. Did the debugger cancel the sig? */
1690 signr = current->exit_code;
1694 current->exit_code = 0;
1696 /* Update the siginfo structure if the signal has
1697 changed. If the debugger wanted something
1698 specific in the siginfo structure then it should
1699 have updated *info via PTRACE_SETSIGINFO. */
1700 if (signr != info->si_signo) {
1701 info->si_signo = signr;
1703 info->si_code = SI_USER;
1704 info->si_pid = task_pid_vnr(current->parent);
1705 info->si_uid = current->parent->uid;
1708 /* If the (new) signal is now blocked, requeue it. */
1709 if (sigismember(¤t->blocked, signr)) {
1710 specific_send_sig_info(signr, info, current);
1717 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1718 struct pt_regs *regs, void *cookie)
1720 struct sighand_struct *sighand = current->sighand;
1721 struct signal_struct *signal = current->signal;
1726 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1727 * While in TASK_STOPPED, we were considered "frozen enough".
1728 * Now that we woke up, it's crucial if we're supposed to be
1729 * frozen that we freeze now before running anything substantial.
1733 spin_lock_irq(&sighand->siglock);
1735 * Every stopped thread goes here after wakeup. Check to see if
1736 * we should notify the parent, prepare_signal(SIGCONT) encodes
1737 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1739 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1740 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1741 ? CLD_CONTINUED : CLD_STOPPED;
1742 signal->flags &= ~SIGNAL_CLD_MASK;
1743 spin_unlock_irq(&sighand->siglock);
1745 if (unlikely(!tracehook_notify_jctl(1, why)))
1748 read_lock(&tasklist_lock);
1749 do_notify_parent_cldstop(current->group_leader, why);
1750 read_unlock(&tasklist_lock);
1755 struct k_sigaction *ka;
1757 if (unlikely(signal->group_stop_count > 0) &&
1762 * Tracing can induce an artifical signal and choose sigaction.
1763 * The return value in @signr determines the default action,
1764 * but @info->si_signo is the signal number we will report.
1766 signr = tracehook_get_signal(current, regs, info, return_ka);
1767 if (unlikely(signr < 0))
1769 if (unlikely(signr != 0))
1772 signr = dequeue_signal(current, ¤t->blocked,
1776 break; /* will return 0 */
1778 if (signr != SIGKILL) {
1779 signr = ptrace_signal(signr, info,
1785 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 (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1810 !signal_group_exit(signal))
1813 if (sig_kernel_stop(signr)) {
1815 * The default action is to stop all threads in
1816 * the thread group. The job control signals
1817 * do nothing in an orphaned pgrp, but SIGSTOP
1818 * always works. Note that siglock needs to be
1819 * dropped during the call to is_orphaned_pgrp()
1820 * because of lock ordering with tasklist_lock.
1821 * This allows an intervening SIGCONT to be posted.
1822 * We need to check for that and bail out if necessary.
1824 if (signr != SIGSTOP) {
1825 spin_unlock_irq(&sighand->siglock);
1827 /* signals can be posted during this window */
1829 if (is_current_pgrp_orphaned())
1832 spin_lock_irq(&sighand->siglock);
1835 if (likely(do_signal_stop(info->si_signo))) {
1836 /* It released the siglock. */
1841 * We didn't actually stop, due to a race
1842 * with SIGCONT or something like that.
1847 spin_unlock_irq(&sighand->siglock);
1850 * Anything else is fatal, maybe with a core dump.
1852 current->flags |= PF_SIGNALED;
1854 if (sig_kernel_coredump(signr)) {
1855 if (print_fatal_signals)
1856 print_fatal_signal(regs, info->si_signo);
1858 * If it was able to dump core, this kills all
1859 * other threads in the group and synchronizes with
1860 * their demise. If we lost the race with another
1861 * thread getting here, it set group_exit_code
1862 * first and our do_group_exit call below will use
1863 * that value and ignore the one we pass it.
1865 do_coredump(info->si_signo, info->si_signo, regs);
1869 * Death signals, no core dump.
1871 do_group_exit(info->si_signo);
1874 spin_unlock_irq(&sighand->siglock);
1878 void exit_signals(struct task_struct *tsk)
1881 struct task_struct *t;
1883 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1884 tsk->flags |= PF_EXITING;
1888 spin_lock_irq(&tsk->sighand->siglock);
1890 * From now this task is not visible for group-wide signals,
1891 * see wants_signal(), do_signal_stop().
1893 tsk->flags |= PF_EXITING;
1894 if (!signal_pending(tsk))
1897 /* It could be that __group_complete_signal() choose us to
1898 * notify about group-wide signal. Another thread should be
1899 * woken now to take the signal since we will not.
1901 for (t = tsk; (t = next_thread(t)) != tsk; )
1902 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1903 recalc_sigpending_and_wake(t);
1905 if (unlikely(tsk->signal->group_stop_count) &&
1906 !--tsk->signal->group_stop_count) {
1907 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1911 spin_unlock_irq(&tsk->sighand->siglock);
1913 if (unlikely(group_stop) && tracehook_notify_jctl(1, CLD_STOPPED)) {
1914 read_lock(&tasklist_lock);
1915 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1916 read_unlock(&tasklist_lock);
1920 EXPORT_SYMBOL(recalc_sigpending);
1921 EXPORT_SYMBOL_GPL(dequeue_signal);
1922 EXPORT_SYMBOL(flush_signals);
1923 EXPORT_SYMBOL(force_sig);
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(pid_t 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(pid_t tgid, pid_t 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(pid_t tgid, pid_t 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(pid_t pid, int sig)
2272 /* This is only valid for single tasks */
2276 return do_tkill(0, pid, sig);
2280 sys_rt_sigqueueinfo(pid_t 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_handler_ignored(sig_handler(t, sig), 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_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);