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 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
603 * Handle magic process-wide effects of stop/continue signals. Unlike
604 * the signal actions, these happen immediately at signal-generation
605 * time regardless of blocking, ignoring, or handling. This does the
606 * actual continuing for SIGCONT, but not the actual stopping for stop
607 * signals. The process stop is done as a signal action for SIG_DFL.
609 * Returns true if the signal should be actually delivered, otherwise
610 * it should be dropped.
612 static int prepare_signal(int sig, struct task_struct *p)
614 struct signal_struct *signal = p->signal;
615 struct task_struct *t;
617 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
619 * The process is in the middle of dying, nothing to do.
621 } else if (sig_kernel_stop(sig)) {
623 * This is a stop signal. Remove SIGCONT from all queues.
625 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
628 rm_from_queue(sigmask(SIGCONT), &t->pending);
629 } while_each_thread(p, t);
630 } else if (sig == SIGCONT) {
633 * Remove all stop signals from all queues,
634 * and wake all threads.
636 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
640 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
642 * If there is a handler for SIGCONT, we must make
643 * sure that no thread returns to user mode before
644 * we post the signal, in case it was the only
645 * thread eligible to run the signal handler--then
646 * it must not do anything between resuming and
647 * running the handler. With the TIF_SIGPENDING
648 * flag set, the thread will pause and acquire the
649 * siglock that we hold now and until we've queued
650 * the pending signal.
652 * Wake up the stopped thread _after_ setting
655 state = __TASK_STOPPED;
656 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
657 set_tsk_thread_flag(t, TIF_SIGPENDING);
658 state |= TASK_INTERRUPTIBLE;
660 wake_up_state(t, state);
661 } while_each_thread(p, t);
664 * Notify the parent with CLD_CONTINUED if we were stopped.
666 * If we were in the middle of a group stop, we pretend it
667 * was already finished, and then continued. Since SIGCHLD
668 * doesn't queue we report only CLD_STOPPED, as if the next
669 * CLD_CONTINUED was dropped.
672 if (signal->flags & SIGNAL_STOP_STOPPED)
673 why |= SIGNAL_CLD_CONTINUED;
674 else if (signal->group_stop_count)
675 why |= SIGNAL_CLD_STOPPED;
679 * The first thread which returns from finish_stop()
680 * will take ->siglock, notice SIGNAL_CLD_MASK, and
681 * notify its parent. See get_signal_to_deliver().
683 signal->flags = why | SIGNAL_STOP_CONTINUED;
684 signal->group_stop_count = 0;
685 signal->group_exit_code = 0;
688 * We are not stopped, but there could be a stop
689 * signal in the middle of being processed after
690 * being removed from the queue. Clear that too.
692 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
696 return !sig_ignored(p, sig);
700 * Test if P wants to take SIG. After we've checked all threads with this,
701 * it's equivalent to finding no threads not blocking SIG. Any threads not
702 * blocking SIG were ruled out because they are not running and already
703 * have pending signals. Such threads will dequeue from the shared queue
704 * as soon as they're available, so putting the signal on the shared queue
705 * will be equivalent to sending it to one such thread.
707 static inline int wants_signal(int sig, struct task_struct *p)
709 if (sigismember(&p->blocked, sig))
711 if (p->flags & PF_EXITING)
715 if (task_is_stopped_or_traced(p))
717 return task_curr(p) || !signal_pending(p);
720 static void complete_signal(int sig, struct task_struct *p, int group)
722 struct signal_struct *signal = p->signal;
723 struct task_struct *t;
726 * Now find a thread we can wake up to take the signal off the queue.
728 * If the main thread wants the signal, it gets first crack.
729 * Probably the least surprising to the average bear.
731 if (wants_signal(sig, p))
733 else if (!group || thread_group_empty(p))
735 * There is just one thread and it does not need to be woken.
736 * It will dequeue unblocked signals before it runs again.
741 * Otherwise try to find a suitable thread.
743 t = signal->curr_target;
744 while (!wants_signal(sig, t)) {
746 if (t == signal->curr_target)
748 * No thread needs to be woken.
749 * Any eligible threads will see
750 * the signal in the queue soon.
754 signal->curr_target = t;
758 * Found a killable thread. If the signal will be fatal,
759 * then start taking the whole group down immediately.
761 if (sig_fatal(p, sig) &&
762 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
763 !sigismember(&t->real_blocked, sig) &&
765 !tracehook_consider_fatal_signal(t, sig, SIG_DFL))) {
767 * This signal will be fatal to the whole group.
769 if (!sig_kernel_coredump(sig)) {
771 * Start a group exit and wake everybody up.
772 * This way we don't have other threads
773 * running and doing things after a slower
774 * thread has the fatal signal pending.
776 signal->flags = SIGNAL_GROUP_EXIT;
777 signal->group_exit_code = sig;
778 signal->group_stop_count = 0;
781 sigaddset(&t->pending.signal, SIGKILL);
782 signal_wake_up(t, 1);
783 } while_each_thread(p, t);
789 * The signal is already in the shared-pending queue.
790 * Tell the chosen thread to wake up and dequeue it.
792 signal_wake_up(t, sig == SIGKILL);
796 static inline int legacy_queue(struct sigpending *signals, int sig)
798 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
801 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
804 struct sigpending *pending;
807 assert_spin_locked(&t->sighand->siglock);
808 if (!prepare_signal(sig, t))
811 pending = group ? &t->signal->shared_pending : &t->pending;
813 * Short-circuit ignored signals and support queuing
814 * exactly one non-rt signal, so that we can get more
815 * detailed information about the cause of the signal.
817 if (legacy_queue(pending, sig))
820 * fast-pathed signals for kernel-internal things like SIGSTOP
823 if (info == SEND_SIG_FORCED)
826 /* Real-time signals must be queued if sent by sigqueue, or
827 some other real-time mechanism. It is implementation
828 defined whether kill() does so. We attempt to do so, on
829 the principle of least surprise, but since kill is not
830 allowed to fail with EAGAIN when low on memory we just
831 make sure at least one signal gets delivered and don't
832 pass on the info struct. */
834 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
835 (is_si_special(info) ||
836 info->si_code >= 0)));
838 list_add_tail(&q->list, &pending->list);
839 switch ((unsigned long) info) {
840 case (unsigned long) SEND_SIG_NOINFO:
841 q->info.si_signo = sig;
842 q->info.si_errno = 0;
843 q->info.si_code = SI_USER;
844 q->info.si_pid = task_pid_vnr(current);
845 q->info.si_uid = current->uid;
847 case (unsigned long) SEND_SIG_PRIV:
848 q->info.si_signo = sig;
849 q->info.si_errno = 0;
850 q->info.si_code = SI_KERNEL;
855 copy_siginfo(&q->info, info);
858 } else if (!is_si_special(info)) {
859 if (sig >= SIGRTMIN && info->si_code != SI_USER)
861 * Queue overflow, abort. We may abort if the signal was rt
862 * and sent by user using something other than kill().
868 signalfd_notify(t, sig);
869 sigaddset(&pending->signal, sig);
870 complete_signal(sig, t, group);
874 int print_fatal_signals;
876 static void print_fatal_signal(struct pt_regs *regs, int signr)
878 printk("%s/%d: potentially unexpected fatal signal %d.\n",
879 current->comm, task_pid_nr(current), signr);
881 #if defined(__i386__) && !defined(__arch_um__)
882 printk("code at %08lx: ", regs->ip);
885 for (i = 0; i < 16; i++) {
888 __get_user(insn, (unsigned char *)(regs->ip + i));
889 printk("%02x ", insn);
897 static int __init setup_print_fatal_signals(char *str)
899 get_option (&str, &print_fatal_signals);
904 __setup("print-fatal-signals=", setup_print_fatal_signals);
907 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
909 return send_signal(sig, info, p, 1);
913 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
915 return send_signal(sig, info, t, 0);
919 * Force a signal that the process can't ignore: if necessary
920 * we unblock the signal and change any SIG_IGN to SIG_DFL.
922 * Note: If we unblock the signal, we always reset it to SIG_DFL,
923 * since we do not want to have a signal handler that was blocked
924 * be invoked when user space had explicitly blocked it.
926 * We don't want to have recursive SIGSEGV's etc, for example,
927 * that is why we also clear SIGNAL_UNKILLABLE.
930 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
932 unsigned long int flags;
933 int ret, blocked, ignored;
934 struct k_sigaction *action;
936 spin_lock_irqsave(&t->sighand->siglock, flags);
937 action = &t->sighand->action[sig-1];
938 ignored = action->sa.sa_handler == SIG_IGN;
939 blocked = sigismember(&t->blocked, sig);
940 if (blocked || ignored) {
941 action->sa.sa_handler = SIG_DFL;
943 sigdelset(&t->blocked, sig);
944 recalc_sigpending_and_wake(t);
947 if (action->sa.sa_handler == SIG_DFL)
948 t->signal->flags &= ~SIGNAL_UNKILLABLE;
949 ret = specific_send_sig_info(sig, info, t);
950 spin_unlock_irqrestore(&t->sighand->siglock, flags);
956 force_sig_specific(int sig, struct task_struct *t)
958 force_sig_info(sig, SEND_SIG_FORCED, t);
962 * Nuke all other threads in the group.
964 void zap_other_threads(struct task_struct *p)
966 struct task_struct *t;
968 p->signal->group_stop_count = 0;
970 for (t = next_thread(p); t != p; t = next_thread(t)) {
972 * Don't bother with already dead threads
977 /* SIGKILL will be handled before any pending SIGSTOP */
978 sigaddset(&t->pending.signal, SIGKILL);
979 signal_wake_up(t, 1);
983 int __fatal_signal_pending(struct task_struct *tsk)
985 return sigismember(&tsk->pending.signal, SIGKILL);
987 EXPORT_SYMBOL(__fatal_signal_pending);
989 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
991 struct sighand_struct *sighand;
995 sighand = rcu_dereference(tsk->sighand);
996 if (unlikely(sighand == NULL))
999 spin_lock_irqsave(&sighand->siglock, *flags);
1000 if (likely(sighand == tsk->sighand))
1002 spin_unlock_irqrestore(&sighand->siglock, *flags);
1009 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1011 unsigned long flags;
1014 ret = check_kill_permission(sig, info, p);
1018 if (lock_task_sighand(p, &flags)) {
1019 ret = __group_send_sig_info(sig, info, p);
1020 unlock_task_sighand(p, &flags);
1028 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1029 * control characters do (^C, ^Z etc)
1032 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1034 struct task_struct *p = NULL;
1035 int retval, success;
1039 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1040 int err = group_send_sig_info(sig, info, p);
1043 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1044 return success ? 0 : retval;
1047 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1050 struct task_struct *p;
1054 p = pid_task(pid, PIDTYPE_PID);
1056 error = group_send_sig_info(sig, info, p);
1057 if (unlikely(error == -ESRCH))
1059 * The task was unhashed in between, try again.
1060 * If it is dead, pid_task() will return NULL,
1061 * if we race with de_thread() it will find the
1072 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1076 error = kill_pid_info(sig, info, find_vpid(pid));
1081 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1082 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1083 uid_t uid, uid_t euid, u32 secid)
1086 struct task_struct *p;
1088 if (!valid_signal(sig))
1091 read_lock(&tasklist_lock);
1092 p = pid_task(pid, PIDTYPE_PID);
1097 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1098 && (euid != p->suid) && (euid != p->uid)
1099 && (uid != p->suid) && (uid != p->uid)) {
1103 ret = security_task_kill(p, info, sig, secid);
1106 if (sig && p->sighand) {
1107 unsigned long flags;
1108 spin_lock_irqsave(&p->sighand->siglock, flags);
1109 ret = __group_send_sig_info(sig, info, p);
1110 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1113 read_unlock(&tasklist_lock);
1116 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1119 * kill_something_info() interprets pid in interesting ways just like kill(2).
1121 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1122 * is probably wrong. Should make it like BSD or SYSV.
1125 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1131 ret = kill_pid_info(sig, info, find_vpid(pid));
1136 read_lock(&tasklist_lock);
1138 ret = __kill_pgrp_info(sig, info,
1139 pid ? find_vpid(-pid) : task_pgrp(current));
1141 int retval = 0, count = 0;
1142 struct task_struct * p;
1144 for_each_process(p) {
1145 if (p->pid > 1 && !same_thread_group(p, current)) {
1146 int err = group_send_sig_info(sig, info, p);
1152 ret = count ? retval : -ESRCH;
1154 read_unlock(&tasklist_lock);
1160 * These are for backward compatibility with the rest of the kernel source.
1164 * The caller must ensure the task can't exit.
1167 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1170 unsigned long flags;
1173 * Make sure legacy kernel users don't send in bad values
1174 * (normal paths check this in check_kill_permission).
1176 if (!valid_signal(sig))
1179 spin_lock_irqsave(&p->sighand->siglock, flags);
1180 ret = specific_send_sig_info(sig, info, p);
1181 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1185 #define __si_special(priv) \
1186 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1189 send_sig(int sig, struct task_struct *p, int priv)
1191 return send_sig_info(sig, __si_special(priv), p);
1195 force_sig(int sig, struct task_struct *p)
1197 force_sig_info(sig, SEND_SIG_PRIV, p);
1201 * When things go south during signal handling, we
1202 * will force a SIGSEGV. And if the signal that caused
1203 * the problem was already a SIGSEGV, we'll want to
1204 * make sure we don't even try to deliver the signal..
1207 force_sigsegv(int sig, struct task_struct *p)
1209 if (sig == SIGSEGV) {
1210 unsigned long flags;
1211 spin_lock_irqsave(&p->sighand->siglock, flags);
1212 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1213 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1215 force_sig(SIGSEGV, p);
1219 int kill_pgrp(struct pid *pid, int sig, int priv)
1223 read_lock(&tasklist_lock);
1224 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1225 read_unlock(&tasklist_lock);
1229 EXPORT_SYMBOL(kill_pgrp);
1231 int kill_pid(struct pid *pid, int sig, int priv)
1233 return kill_pid_info(sig, __si_special(priv), pid);
1235 EXPORT_SYMBOL(kill_pid);
1238 * These functions support sending signals using preallocated sigqueue
1239 * structures. This is needed "because realtime applications cannot
1240 * afford to lose notifications of asynchronous events, like timer
1241 * expirations or I/O completions". In the case of Posix Timers
1242 * we allocate the sigqueue structure from the timer_create. If this
1243 * allocation fails we are able to report the failure to the application
1244 * with an EAGAIN error.
1247 struct sigqueue *sigqueue_alloc(void)
1251 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1252 q->flags |= SIGQUEUE_PREALLOC;
1256 void sigqueue_free(struct sigqueue *q)
1258 unsigned long flags;
1259 spinlock_t *lock = ¤t->sighand->siglock;
1261 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1263 * We must hold ->siglock while testing q->list
1264 * to serialize with collect_signal() or with
1265 * __exit_signal()->flush_sigqueue().
1267 spin_lock_irqsave(lock, flags);
1268 q->flags &= ~SIGQUEUE_PREALLOC;
1270 * If it is queued it will be freed when dequeued,
1271 * like the "regular" sigqueue.
1273 if (!list_empty(&q->list))
1275 spin_unlock_irqrestore(lock, flags);
1281 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1283 int sig = q->info.si_signo;
1284 struct sigpending *pending;
1285 unsigned long flags;
1288 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1291 if (!likely(lock_task_sighand(t, &flags)))
1294 ret = 1; /* the signal is ignored */
1295 if (!prepare_signal(sig, t))
1299 if (unlikely(!list_empty(&q->list))) {
1301 * If an SI_TIMER entry is already queue just increment
1302 * the overrun count.
1304 BUG_ON(q->info.si_code != SI_TIMER);
1305 q->info.si_overrun++;
1309 signalfd_notify(t, sig);
1310 pending = group ? &t->signal->shared_pending : &t->pending;
1311 list_add_tail(&q->list, &pending->list);
1312 sigaddset(&pending->signal, sig);
1313 complete_signal(sig, t, group);
1315 unlock_task_sighand(t, &flags);
1321 * Wake up any threads in the parent blocked in wait* syscalls.
1323 static inline void __wake_up_parent(struct task_struct *p,
1324 struct task_struct *parent)
1326 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1330 * Let a parent know about the death of a child.
1331 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1334 void do_notify_parent(struct task_struct *tsk, int sig)
1336 struct siginfo info;
1337 unsigned long flags;
1338 struct sighand_struct *psig;
1342 /* do_notify_parent_cldstop should have been called instead. */
1343 BUG_ON(task_is_stopped_or_traced(tsk));
1345 BUG_ON(!tsk->ptrace &&
1346 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1348 info.si_signo = sig;
1351 * we are under tasklist_lock here so our parent is tied to
1352 * us and cannot exit and release its namespace.
1354 * the only it can is to switch its nsproxy with sys_unshare,
1355 * bu uncharing pid namespaces is not allowed, so we'll always
1356 * see relevant namespace
1358 * write_lock() currently calls preempt_disable() which is the
1359 * same as rcu_read_lock(), but according to Oleg, this is not
1360 * correct to rely on this
1363 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1366 info.si_uid = tsk->uid;
1368 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1369 tsk->signal->utime));
1370 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1371 tsk->signal->stime));
1373 info.si_status = tsk->exit_code & 0x7f;
1374 if (tsk->exit_code & 0x80)
1375 info.si_code = CLD_DUMPED;
1376 else if (tsk->exit_code & 0x7f)
1377 info.si_code = CLD_KILLED;
1379 info.si_code = CLD_EXITED;
1380 info.si_status = tsk->exit_code >> 8;
1383 psig = tsk->parent->sighand;
1384 spin_lock_irqsave(&psig->siglock, flags);
1385 if (!tsk->ptrace && sig == SIGCHLD &&
1386 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1387 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1389 * We are exiting and our parent doesn't care. POSIX.1
1390 * defines special semantics for setting SIGCHLD to SIG_IGN
1391 * or setting the SA_NOCLDWAIT flag: we should be reaped
1392 * automatically and not left for our parent's wait4 call.
1393 * Rather than having the parent do it as a magic kind of
1394 * signal handler, we just set this to tell do_exit that we
1395 * can be cleaned up without becoming a zombie. Note that
1396 * we still call __wake_up_parent in this case, because a
1397 * blocked sys_wait4 might now return -ECHILD.
1399 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1400 * is implementation-defined: we do (if you don't want
1401 * it, just use SIG_IGN instead).
1403 tsk->exit_signal = -1;
1404 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1407 if (valid_signal(sig) && sig > 0)
1408 __group_send_sig_info(sig, &info, tsk->parent);
1409 __wake_up_parent(tsk, tsk->parent);
1410 spin_unlock_irqrestore(&psig->siglock, flags);
1413 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1415 struct siginfo info;
1416 unsigned long flags;
1417 struct task_struct *parent;
1418 struct sighand_struct *sighand;
1420 if (tsk->ptrace & PT_PTRACED)
1421 parent = tsk->parent;
1423 tsk = tsk->group_leader;
1424 parent = tsk->real_parent;
1427 info.si_signo = SIGCHLD;
1430 * see comment in do_notify_parent() abot the following 3 lines
1433 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1436 info.si_uid = tsk->uid;
1438 info.si_utime = cputime_to_clock_t(tsk->utime);
1439 info.si_stime = cputime_to_clock_t(tsk->stime);
1444 info.si_status = SIGCONT;
1447 info.si_status = tsk->signal->group_exit_code & 0x7f;
1450 info.si_status = tsk->exit_code & 0x7f;
1456 sighand = parent->sighand;
1457 spin_lock_irqsave(&sighand->siglock, flags);
1458 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1459 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1460 __group_send_sig_info(SIGCHLD, &info, parent);
1462 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1464 __wake_up_parent(tsk, parent);
1465 spin_unlock_irqrestore(&sighand->siglock, flags);
1468 static inline int may_ptrace_stop(void)
1470 if (!likely(current->ptrace & PT_PTRACED))
1473 * Are we in the middle of do_coredump?
1474 * If so and our tracer is also part of the coredump stopping
1475 * is a deadlock situation, and pointless because our tracer
1476 * is dead so don't allow us to stop.
1477 * If SIGKILL was already sent before the caller unlocked
1478 * ->siglock we must see ->core_state != NULL. Otherwise it
1479 * is safe to enter schedule().
1481 if (unlikely(current->mm->core_state) &&
1482 unlikely(current->mm == current->parent->mm))
1489 * Return nonzero if there is a SIGKILL that should be waking us up.
1490 * Called with the siglock held.
1492 static int sigkill_pending(struct task_struct *tsk)
1494 return sigismember(&tsk->pending.signal, SIGKILL) ||
1495 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1499 * This must be called with current->sighand->siglock held.
1501 * This should be the path for all ptrace stops.
1502 * We always set current->last_siginfo while stopped here.
1503 * That makes it a way to test a stopped process for
1504 * being ptrace-stopped vs being job-control-stopped.
1506 * If we actually decide not to stop at all because the tracer
1507 * is gone, we keep current->exit_code unless clear_code.
1509 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1511 if (arch_ptrace_stop_needed(exit_code, info)) {
1513 * The arch code has something special to do before a
1514 * ptrace stop. This is allowed to block, e.g. for faults
1515 * on user stack pages. We can't keep the siglock while
1516 * calling arch_ptrace_stop, so we must release it now.
1517 * To preserve proper semantics, we must do this before
1518 * any signal bookkeeping like checking group_stop_count.
1519 * Meanwhile, a SIGKILL could come in before we retake the
1520 * siglock. That must prevent us from sleeping in TASK_TRACED.
1521 * So after regaining the lock, we must check for SIGKILL.
1523 spin_unlock_irq(¤t->sighand->siglock);
1524 arch_ptrace_stop(exit_code, info);
1525 spin_lock_irq(¤t->sighand->siglock);
1526 if (sigkill_pending(current))
1531 * If there is a group stop in progress,
1532 * we must participate in the bookkeeping.
1534 if (current->signal->group_stop_count > 0)
1535 --current->signal->group_stop_count;
1537 current->last_siginfo = info;
1538 current->exit_code = exit_code;
1540 /* Let the debugger run. */
1541 __set_current_state(TASK_TRACED);
1542 spin_unlock_irq(¤t->sighand->siglock);
1543 read_lock(&tasklist_lock);
1544 if (may_ptrace_stop()) {
1545 do_notify_parent_cldstop(current, CLD_TRAPPED);
1546 read_unlock(&tasklist_lock);
1550 * By the time we got the lock, our tracer went away.
1551 * Don't drop the lock yet, another tracer may come.
1553 __set_current_state(TASK_RUNNING);
1555 current->exit_code = 0;
1556 read_unlock(&tasklist_lock);
1560 * While in TASK_TRACED, we were considered "frozen enough".
1561 * Now that we woke up, it's crucial if we're supposed to be
1562 * frozen that we freeze now before running anything substantial.
1567 * We are back. Now reacquire the siglock before touching
1568 * last_siginfo, so that we are sure to have synchronized with
1569 * any signal-sending on another CPU that wants to examine it.
1571 spin_lock_irq(¤t->sighand->siglock);
1572 current->last_siginfo = NULL;
1575 * Queued signals ignored us while we were stopped for tracing.
1576 * So check for any that we should take before resuming user mode.
1577 * This sets TIF_SIGPENDING, but never clears it.
1579 recalc_sigpending_tsk(current);
1582 void ptrace_notify(int exit_code)
1586 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1588 memset(&info, 0, sizeof info);
1589 info.si_signo = SIGTRAP;
1590 info.si_code = exit_code;
1591 info.si_pid = task_pid_vnr(current);
1592 info.si_uid = current->uid;
1594 /* Let the debugger run. */
1595 spin_lock_irq(¤t->sighand->siglock);
1596 ptrace_stop(exit_code, 1, &info);
1597 spin_unlock_irq(¤t->sighand->siglock);
1601 finish_stop(int stop_count)
1604 * If there are no other threads in the group, or if there is
1605 * a group stop in progress and we are the last to stop,
1606 * report to the parent. When ptraced, every thread reports itself.
1608 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1609 read_lock(&tasklist_lock);
1610 do_notify_parent_cldstop(current, CLD_STOPPED);
1611 read_unlock(&tasklist_lock);
1616 } while (try_to_freeze());
1618 * Now we don't run again until continued.
1620 current->exit_code = 0;
1624 * This performs the stopping for SIGSTOP and other stop signals.
1625 * We have to stop all threads in the thread group.
1626 * Returns nonzero if we've actually stopped and released the siglock.
1627 * Returns zero if we didn't stop and still hold the siglock.
1629 static int do_signal_stop(int signr)
1631 struct signal_struct *sig = current->signal;
1634 if (sig->group_stop_count > 0) {
1636 * There is a group stop in progress. We don't need to
1637 * start another one.
1639 stop_count = --sig->group_stop_count;
1641 struct task_struct *t;
1643 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1644 unlikely(signal_group_exit(sig)))
1647 * There is no group stop already in progress.
1648 * We must initiate one now.
1650 sig->group_exit_code = signr;
1653 for (t = next_thread(current); t != current; t = next_thread(t))
1655 * Setting state to TASK_STOPPED for a group
1656 * stop is always done with the siglock held,
1657 * so this check has no races.
1659 if (!(t->flags & PF_EXITING) &&
1660 !task_is_stopped_or_traced(t)) {
1662 signal_wake_up(t, 0);
1664 sig->group_stop_count = stop_count;
1667 if (stop_count == 0)
1668 sig->flags = SIGNAL_STOP_STOPPED;
1669 current->exit_code = sig->group_exit_code;
1670 __set_current_state(TASK_STOPPED);
1672 spin_unlock_irq(¤t->sighand->siglock);
1673 finish_stop(stop_count);
1677 static int ptrace_signal(int signr, siginfo_t *info,
1678 struct pt_regs *regs, void *cookie)
1680 if (!(current->ptrace & PT_PTRACED))
1683 ptrace_signal_deliver(regs, cookie);
1685 /* Let the debugger run. */
1686 ptrace_stop(signr, 0, info);
1688 /* We're back. Did the debugger cancel the sig? */
1689 signr = current->exit_code;
1693 current->exit_code = 0;
1695 /* Update the siginfo structure if the signal has
1696 changed. If the debugger wanted something
1697 specific in the siginfo structure then it should
1698 have updated *info via PTRACE_SETSIGINFO. */
1699 if (signr != info->si_signo) {
1700 info->si_signo = signr;
1702 info->si_code = SI_USER;
1703 info->si_pid = task_pid_vnr(current->parent);
1704 info->si_uid = current->parent->uid;
1707 /* If the (new) signal is now blocked, requeue it. */
1708 if (sigismember(¤t->blocked, signr)) {
1709 specific_send_sig_info(signr, info, current);
1716 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1717 struct pt_regs *regs, void *cookie)
1719 struct sighand_struct *sighand = current->sighand;
1720 struct signal_struct *signal = current->signal;
1725 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1726 * While in TASK_STOPPED, we were considered "frozen enough".
1727 * Now that we woke up, it's crucial if we're supposed to be
1728 * frozen that we freeze now before running anything substantial.
1732 spin_lock_irq(&sighand->siglock);
1734 * Every stopped thread goes here after wakeup. Check to see if
1735 * we should notify the parent, prepare_signal(SIGCONT) encodes
1736 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1738 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1739 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1740 ? CLD_CONTINUED : CLD_STOPPED;
1741 signal->flags &= ~SIGNAL_CLD_MASK;
1742 spin_unlock_irq(&sighand->siglock);
1744 read_lock(&tasklist_lock);
1745 do_notify_parent_cldstop(current->group_leader, why);
1746 read_unlock(&tasklist_lock);
1751 struct k_sigaction *ka;
1753 if (unlikely(signal->group_stop_count > 0) &&
1758 * Tracing can induce an artifical signal and choose sigaction.
1759 * The return value in @signr determines the default action,
1760 * but @info->si_signo is the signal number we will report.
1762 signr = tracehook_get_signal(current, regs, info, return_ka);
1763 if (unlikely(signr < 0))
1765 if (unlikely(signr != 0))
1768 signr = dequeue_signal(current, ¤t->blocked,
1772 break; /* will return 0 */
1774 if (signr != SIGKILL) {
1775 signr = ptrace_signal(signr, info,
1781 ka = &sighand->action[signr-1];
1784 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1786 if (ka->sa.sa_handler != SIG_DFL) {
1787 /* Run the handler. */
1790 if (ka->sa.sa_flags & SA_ONESHOT)
1791 ka->sa.sa_handler = SIG_DFL;
1793 break; /* will return non-zero "signr" value */
1797 * Now we are doing the default action for this signal.
1799 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1803 * Global init gets no signals it doesn't want.
1805 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1806 !signal_group_exit(signal))
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(info->si_signo))) {
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;
1850 if (sig_kernel_coredump(signr)) {
1851 if (print_fatal_signals)
1852 print_fatal_signal(regs, info->si_signo);
1854 * If it was able to dump core, this kills all
1855 * other threads in the group and synchronizes with
1856 * their demise. If we lost the race with another
1857 * thread getting here, it set group_exit_code
1858 * first and our do_group_exit call below will use
1859 * that value and ignore the one we pass it.
1861 do_coredump(info->si_signo, info->si_signo, regs);
1865 * Death signals, no core dump.
1867 do_group_exit(info->si_signo);
1870 spin_unlock_irq(&sighand->siglock);
1874 void exit_signals(struct task_struct *tsk)
1877 struct task_struct *t;
1879 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1880 tsk->flags |= PF_EXITING;
1884 spin_lock_irq(&tsk->sighand->siglock);
1886 * From now this task is not visible for group-wide signals,
1887 * see wants_signal(), do_signal_stop().
1889 tsk->flags |= PF_EXITING;
1890 if (!signal_pending(tsk))
1893 /* It could be that __group_complete_signal() choose us to
1894 * notify about group-wide signal. Another thread should be
1895 * woken now to take the signal since we will not.
1897 for (t = tsk; (t = next_thread(t)) != tsk; )
1898 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1899 recalc_sigpending_and_wake(t);
1901 if (unlikely(tsk->signal->group_stop_count) &&
1902 !--tsk->signal->group_stop_count) {
1903 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1907 spin_unlock_irq(&tsk->sighand->siglock);
1909 if (unlikely(group_stop)) {
1910 read_lock(&tasklist_lock);
1911 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1912 read_unlock(&tasklist_lock);
1916 EXPORT_SYMBOL(recalc_sigpending);
1917 EXPORT_SYMBOL_GPL(dequeue_signal);
1918 EXPORT_SYMBOL(flush_signals);
1919 EXPORT_SYMBOL(force_sig);
1920 EXPORT_SYMBOL(send_sig);
1921 EXPORT_SYMBOL(send_sig_info);
1922 EXPORT_SYMBOL(sigprocmask);
1923 EXPORT_SYMBOL(block_all_signals);
1924 EXPORT_SYMBOL(unblock_all_signals);
1928 * System call entry points.
1931 asmlinkage long sys_restart_syscall(void)
1933 struct restart_block *restart = ¤t_thread_info()->restart_block;
1934 return restart->fn(restart);
1937 long do_no_restart_syscall(struct restart_block *param)
1943 * We don't need to get the kernel lock - this is all local to this
1944 * particular thread.. (and that's good, because this is _heavily_
1945 * used by various programs)
1949 * This is also useful for kernel threads that want to temporarily
1950 * (or permanently) block certain signals.
1952 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1953 * interface happily blocks "unblockable" signals like SIGKILL
1956 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1960 spin_lock_irq(¤t->sighand->siglock);
1962 *oldset = current->blocked;
1967 sigorsets(¤t->blocked, ¤t->blocked, set);
1970 signandsets(¤t->blocked, ¤t->blocked, set);
1973 current->blocked = *set;
1978 recalc_sigpending();
1979 spin_unlock_irq(¤t->sighand->siglock);
1985 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1987 int error = -EINVAL;
1988 sigset_t old_set, new_set;
1990 /* XXX: Don't preclude handling different sized sigset_t's. */
1991 if (sigsetsize != sizeof(sigset_t))
1996 if (copy_from_user(&new_set, set, sizeof(*set)))
1998 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2000 error = sigprocmask(how, &new_set, &old_set);
2006 spin_lock_irq(¤t->sighand->siglock);
2007 old_set = current->blocked;
2008 spin_unlock_irq(¤t->sighand->siglock);
2012 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2020 long do_sigpending(void __user *set, unsigned long sigsetsize)
2022 long error = -EINVAL;
2025 if (sigsetsize > sizeof(sigset_t))
2028 spin_lock_irq(¤t->sighand->siglock);
2029 sigorsets(&pending, ¤t->pending.signal,
2030 ¤t->signal->shared_pending.signal);
2031 spin_unlock_irq(¤t->sighand->siglock);
2033 /* Outside the lock because only this thread touches it. */
2034 sigandsets(&pending, ¤t->blocked, &pending);
2037 if (!copy_to_user(set, &pending, sigsetsize))
2045 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2047 return do_sigpending(set, sigsetsize);
2050 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2052 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2056 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2058 if (from->si_code < 0)
2059 return __copy_to_user(to, from, sizeof(siginfo_t))
2062 * If you change siginfo_t structure, please be sure
2063 * this code is fixed accordingly.
2064 * Please remember to update the signalfd_copyinfo() function
2065 * inside fs/signalfd.c too, in case siginfo_t changes.
2066 * It should never copy any pad contained in the structure
2067 * to avoid security leaks, but must copy the generic
2068 * 3 ints plus the relevant union member.
2070 err = __put_user(from->si_signo, &to->si_signo);
2071 err |= __put_user(from->si_errno, &to->si_errno);
2072 err |= __put_user((short)from->si_code, &to->si_code);
2073 switch (from->si_code & __SI_MASK) {
2075 err |= __put_user(from->si_pid, &to->si_pid);
2076 err |= __put_user(from->si_uid, &to->si_uid);
2079 err |= __put_user(from->si_tid, &to->si_tid);
2080 err |= __put_user(from->si_overrun, &to->si_overrun);
2081 err |= __put_user(from->si_ptr, &to->si_ptr);
2084 err |= __put_user(from->si_band, &to->si_band);
2085 err |= __put_user(from->si_fd, &to->si_fd);
2088 err |= __put_user(from->si_addr, &to->si_addr);
2089 #ifdef __ARCH_SI_TRAPNO
2090 err |= __put_user(from->si_trapno, &to->si_trapno);
2094 err |= __put_user(from->si_pid, &to->si_pid);
2095 err |= __put_user(from->si_uid, &to->si_uid);
2096 err |= __put_user(from->si_status, &to->si_status);
2097 err |= __put_user(from->si_utime, &to->si_utime);
2098 err |= __put_user(from->si_stime, &to->si_stime);
2100 case __SI_RT: /* This is not generated by the kernel as of now. */
2101 case __SI_MESGQ: /* But this is */
2102 err |= __put_user(from->si_pid, &to->si_pid);
2103 err |= __put_user(from->si_uid, &to->si_uid);
2104 err |= __put_user(from->si_ptr, &to->si_ptr);
2106 default: /* this is just in case for now ... */
2107 err |= __put_user(from->si_pid, &to->si_pid);
2108 err |= __put_user(from->si_uid, &to->si_uid);
2117 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2118 siginfo_t __user *uinfo,
2119 const struct timespec __user *uts,
2128 /* XXX: Don't preclude handling different sized sigset_t's. */
2129 if (sigsetsize != sizeof(sigset_t))
2132 if (copy_from_user(&these, uthese, sizeof(these)))
2136 * Invert the set of allowed signals to get those we
2139 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2143 if (copy_from_user(&ts, uts, sizeof(ts)))
2145 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2150 spin_lock_irq(¤t->sighand->siglock);
2151 sig = dequeue_signal(current, &these, &info);
2153 timeout = MAX_SCHEDULE_TIMEOUT;
2155 timeout = (timespec_to_jiffies(&ts)
2156 + (ts.tv_sec || ts.tv_nsec));
2159 /* None ready -- temporarily unblock those we're
2160 * interested while we are sleeping in so that we'll
2161 * be awakened when they arrive. */
2162 current->real_blocked = current->blocked;
2163 sigandsets(¤t->blocked, ¤t->blocked, &these);
2164 recalc_sigpending();
2165 spin_unlock_irq(¤t->sighand->siglock);
2167 timeout = schedule_timeout_interruptible(timeout);
2169 spin_lock_irq(¤t->sighand->siglock);
2170 sig = dequeue_signal(current, &these, &info);
2171 current->blocked = current->real_blocked;
2172 siginitset(¤t->real_blocked, 0);
2173 recalc_sigpending();
2176 spin_unlock_irq(¤t->sighand->siglock);
2181 if (copy_siginfo_to_user(uinfo, &info))
2194 sys_kill(pid_t pid, int sig)
2196 struct siginfo info;
2198 info.si_signo = sig;
2200 info.si_code = SI_USER;
2201 info.si_pid = task_tgid_vnr(current);
2202 info.si_uid = current->uid;
2204 return kill_something_info(sig, &info, pid);
2207 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2210 struct siginfo info;
2211 struct task_struct *p;
2212 unsigned long flags;
2215 info.si_signo = sig;
2217 info.si_code = SI_TKILL;
2218 info.si_pid = task_tgid_vnr(current);
2219 info.si_uid = current->uid;
2222 p = find_task_by_vpid(pid);
2223 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2224 error = check_kill_permission(sig, &info, p);
2226 * The null signal is a permissions and process existence
2227 * probe. No signal is actually delivered.
2229 * If lock_task_sighand() fails we pretend the task dies
2230 * after receiving the signal. The window is tiny, and the
2231 * signal is private anyway.
2233 if (!error && sig && lock_task_sighand(p, &flags)) {
2234 error = specific_send_sig_info(sig, &info, p);
2235 unlock_task_sighand(p, &flags);
2244 * sys_tgkill - send signal to one specific thread
2245 * @tgid: the thread group ID of the thread
2246 * @pid: the PID of the thread
2247 * @sig: signal to be sent
2249 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2250 * exists but it's not belonging to the target process anymore. This
2251 * method solves the problem of threads exiting and PIDs getting reused.
2253 asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig)
2255 /* This is only valid for single tasks */
2256 if (pid <= 0 || tgid <= 0)
2259 return do_tkill(tgid, pid, sig);
2263 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2266 sys_tkill(pid_t pid, int sig)
2268 /* This is only valid for single tasks */
2272 return do_tkill(0, pid, sig);
2276 sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo)
2280 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2283 /* Not even root can pretend to send signals from the kernel.
2284 Nor can they impersonate a kill(), which adds source info. */
2285 if (info.si_code >= 0)
2287 info.si_signo = sig;
2289 /* POSIX.1b doesn't mention process groups. */
2290 return kill_proc_info(sig, &info, pid);
2293 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2295 struct task_struct *t = current;
2296 struct k_sigaction *k;
2299 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2302 k = &t->sighand->action[sig-1];
2304 spin_lock_irq(¤t->sighand->siglock);
2309 sigdelsetmask(&act->sa.sa_mask,
2310 sigmask(SIGKILL) | sigmask(SIGSTOP));
2314 * "Setting a signal action to SIG_IGN for a signal that is
2315 * pending shall cause the pending signal to be discarded,
2316 * whether or not it is blocked."
2318 * "Setting a signal action to SIG_DFL for a signal that is
2319 * pending and whose default action is to ignore the signal
2320 * (for example, SIGCHLD), shall cause the pending signal to
2321 * be discarded, whether or not it is blocked"
2323 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2325 sigaddset(&mask, sig);
2326 rm_from_queue_full(&mask, &t->signal->shared_pending);
2328 rm_from_queue_full(&mask, &t->pending);
2330 } while (t != current);
2334 spin_unlock_irq(¤t->sighand->siglock);
2339 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2345 oss.ss_sp = (void __user *) current->sas_ss_sp;
2346 oss.ss_size = current->sas_ss_size;
2347 oss.ss_flags = sas_ss_flags(sp);
2356 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2357 || __get_user(ss_sp, &uss->ss_sp)
2358 || __get_user(ss_flags, &uss->ss_flags)
2359 || __get_user(ss_size, &uss->ss_size))
2363 if (on_sig_stack(sp))
2369 * Note - this code used to test ss_flags incorrectly
2370 * old code may have been written using ss_flags==0
2371 * to mean ss_flags==SS_ONSTACK (as this was the only
2372 * way that worked) - this fix preserves that older
2375 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2378 if (ss_flags == SS_DISABLE) {
2383 if (ss_size < MINSIGSTKSZ)
2387 current->sas_ss_sp = (unsigned long) ss_sp;
2388 current->sas_ss_size = ss_size;
2393 if (copy_to_user(uoss, &oss, sizeof(oss)))
2402 #ifdef __ARCH_WANT_SYS_SIGPENDING
2405 sys_sigpending(old_sigset_t __user *set)
2407 return do_sigpending(set, sizeof(*set));
2412 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2413 /* Some platforms have their own version with special arguments others
2414 support only sys_rt_sigprocmask. */
2417 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2420 old_sigset_t old_set, new_set;
2424 if (copy_from_user(&new_set, set, sizeof(*set)))
2426 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2428 spin_lock_irq(¤t->sighand->siglock);
2429 old_set = current->blocked.sig[0];
2437 sigaddsetmask(¤t->blocked, new_set);
2440 sigdelsetmask(¤t->blocked, new_set);
2443 current->blocked.sig[0] = new_set;
2447 recalc_sigpending();
2448 spin_unlock_irq(¤t->sighand->siglock);
2454 old_set = current->blocked.sig[0];
2457 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2464 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2466 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2468 sys_rt_sigaction(int sig,
2469 const struct sigaction __user *act,
2470 struct sigaction __user *oact,
2473 struct k_sigaction new_sa, old_sa;
2476 /* XXX: Don't preclude handling different sized sigset_t's. */
2477 if (sigsetsize != sizeof(sigset_t))
2481 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2485 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2488 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2494 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2496 #ifdef __ARCH_WANT_SYS_SGETMASK
2499 * For backwards compatibility. Functionality superseded by sigprocmask.
2505 return current->blocked.sig[0];
2509 sys_ssetmask(int newmask)
2513 spin_lock_irq(¤t->sighand->siglock);
2514 old = current->blocked.sig[0];
2516 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2518 recalc_sigpending();
2519 spin_unlock_irq(¤t->sighand->siglock);
2523 #endif /* __ARCH_WANT_SGETMASK */
2525 #ifdef __ARCH_WANT_SYS_SIGNAL
2527 * For backwards compatibility. Functionality superseded by sigaction.
2529 asmlinkage unsigned long
2530 sys_signal(int sig, __sighandler_t handler)
2532 struct k_sigaction new_sa, old_sa;
2535 new_sa.sa.sa_handler = handler;
2536 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2537 sigemptyset(&new_sa.sa.sa_mask);
2539 ret = do_sigaction(sig, &new_sa, &old_sa);
2541 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2543 #endif /* __ARCH_WANT_SYS_SIGNAL */
2545 #ifdef __ARCH_WANT_SYS_PAUSE
2550 current->state = TASK_INTERRUPTIBLE;
2552 return -ERESTARTNOHAND;
2557 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2558 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2562 /* XXX: Don't preclude handling different sized sigset_t's. */
2563 if (sigsetsize != sizeof(sigset_t))
2566 if (copy_from_user(&newset, unewset, sizeof(newset)))
2568 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2570 spin_lock_irq(¤t->sighand->siglock);
2571 current->saved_sigmask = current->blocked;
2572 current->blocked = newset;
2573 recalc_sigpending();
2574 spin_unlock_irq(¤t->sighand->siglock);
2576 current->state = TASK_INTERRUPTIBLE;
2578 set_restore_sigmask();
2579 return -ERESTARTNOHAND;
2581 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2583 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2588 void __init signals_init(void)
2590 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);