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 (unlikely(tracehook_force_sigpending()))
138 set_thread_flag(TIF_SIGPENDING);
139 else if (!recalc_sigpending_tsk(current) && !freezing(current))
140 clear_thread_flag(TIF_SIGPENDING);
144 /* Given the mask, find the first available signal that should be serviced. */
146 int next_signal(struct sigpending *pending, sigset_t *mask)
148 unsigned long i, *s, *m, x;
151 s = pending->signal.sig;
153 switch (_NSIG_WORDS) {
155 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
156 if ((x = *s &~ *m) != 0) {
157 sig = ffz(~x) + i*_NSIG_BPW + 1;
162 case 2: if ((x = s[0] &~ m[0]) != 0)
164 else if ((x = s[1] &~ m[1]) != 0)
171 case 1: if ((x = *s &~ *m) != 0)
179 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
182 struct sigqueue *q = NULL;
183 struct user_struct *user;
186 * In order to avoid problems with "switch_user()", we want to make
187 * sure that the compiler doesn't re-load "t->user"
191 atomic_inc(&user->sigpending);
192 if (override_rlimit ||
193 atomic_read(&user->sigpending) <=
194 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
195 q = kmem_cache_alloc(sigqueue_cachep, flags);
196 if (unlikely(q == NULL)) {
197 atomic_dec(&user->sigpending);
199 INIT_LIST_HEAD(&q->list);
201 q->user = get_uid(user);
206 static void __sigqueue_free(struct sigqueue *q)
208 if (q->flags & SIGQUEUE_PREALLOC)
210 atomic_dec(&q->user->sigpending);
212 kmem_cache_free(sigqueue_cachep, q);
215 void flush_sigqueue(struct sigpending *queue)
219 sigemptyset(&queue->signal);
220 while (!list_empty(&queue->list)) {
221 q = list_entry(queue->list.next, struct sigqueue , list);
222 list_del_init(&q->list);
228 * Flush all pending signals for a task.
230 void flush_signals(struct task_struct *t)
234 spin_lock_irqsave(&t->sighand->siglock, flags);
235 clear_tsk_thread_flag(t, TIF_SIGPENDING);
236 flush_sigqueue(&t->pending);
237 flush_sigqueue(&t->signal->shared_pending);
238 spin_unlock_irqrestore(&t->sighand->siglock, flags);
241 static void __flush_itimer_signals(struct sigpending *pending)
243 sigset_t signal, retain;
244 struct sigqueue *q, *n;
246 signal = pending->signal;
247 sigemptyset(&retain);
249 list_for_each_entry_safe(q, n, &pending->list, list) {
250 int sig = q->info.si_signo;
252 if (likely(q->info.si_code != SI_TIMER)) {
253 sigaddset(&retain, sig);
255 sigdelset(&signal, sig);
256 list_del_init(&q->list);
261 sigorsets(&pending->signal, &signal, &retain);
264 void flush_itimer_signals(void)
266 struct task_struct *tsk = current;
269 spin_lock_irqsave(&tsk->sighand->siglock, flags);
270 __flush_itimer_signals(&tsk->pending);
271 __flush_itimer_signals(&tsk->signal->shared_pending);
272 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
275 void ignore_signals(struct task_struct *t)
279 for (i = 0; i < _NSIG; ++i)
280 t->sighand->action[i].sa.sa_handler = SIG_IGN;
286 * Flush all handlers for a task.
290 flush_signal_handlers(struct task_struct *t, int force_default)
293 struct k_sigaction *ka = &t->sighand->action[0];
294 for (i = _NSIG ; i != 0 ; i--) {
295 if (force_default || ka->sa.sa_handler != SIG_IGN)
296 ka->sa.sa_handler = SIG_DFL;
298 sigemptyset(&ka->sa.sa_mask);
303 int unhandled_signal(struct task_struct *tsk, int sig)
305 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
306 if (is_global_init(tsk))
308 if (handler != SIG_IGN && handler != SIG_DFL)
310 return !tracehook_consider_fatal_signal(tsk, sig, handler);
314 /* Notify the system that a driver wants to block all signals for this
315 * process, and wants to be notified if any signals at all were to be
316 * sent/acted upon. If the notifier routine returns non-zero, then the
317 * signal will be acted upon after all. If the notifier routine returns 0,
318 * then then signal will be blocked. Only one block per process is
319 * allowed. priv is a pointer to private data that the notifier routine
320 * can use to determine if the signal should be blocked or not. */
323 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
327 spin_lock_irqsave(¤t->sighand->siglock, flags);
328 current->notifier_mask = mask;
329 current->notifier_data = priv;
330 current->notifier = notifier;
331 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
334 /* Notify the system that blocking has ended. */
337 unblock_all_signals(void)
341 spin_lock_irqsave(¤t->sighand->siglock, flags);
342 current->notifier = NULL;
343 current->notifier_data = NULL;
345 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
348 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
350 struct sigqueue *q, *first = NULL;
353 * Collect the siginfo appropriate to this signal. Check if
354 * there is another siginfo for the same signal.
356 list_for_each_entry(q, &list->list, list) {
357 if (q->info.si_signo == sig) {
364 sigdelset(&list->signal, sig);
368 list_del_init(&first->list);
369 copy_siginfo(info, &first->info);
370 __sigqueue_free(first);
372 /* Ok, it wasn't in the queue. This must be
373 a fast-pathed signal or we must have been
374 out of queue space. So zero out the info.
376 info->si_signo = sig;
384 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
387 int sig = next_signal(pending, mask);
390 if (current->notifier) {
391 if (sigismember(current->notifier_mask, sig)) {
392 if (!(current->notifier)(current->notifier_data)) {
393 clear_thread_flag(TIF_SIGPENDING);
399 collect_signal(sig, pending, info);
406 * Dequeue a signal and return the element to the caller, which is
407 * expected to free it.
409 * All callers have to hold the siglock.
411 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
415 /* We only dequeue private signals from ourselves, we don't let
416 * signalfd steal them
418 signr = __dequeue_signal(&tsk->pending, mask, info);
420 signr = __dequeue_signal(&tsk->signal->shared_pending,
425 * itimers are process shared and we restart periodic
426 * itimers in the signal delivery path to prevent DoS
427 * attacks in the high resolution timer case. This is
428 * compliant with the old way of self restarting
429 * itimers, as the SIGALRM is a legacy signal and only
430 * queued once. Changing the restart behaviour to
431 * restart the timer in the signal dequeue path is
432 * reducing the timer noise on heavy loaded !highres
435 if (unlikely(signr == SIGALRM)) {
436 struct hrtimer *tmr = &tsk->signal->real_timer;
438 if (!hrtimer_is_queued(tmr) &&
439 tsk->signal->it_real_incr.tv64 != 0) {
440 hrtimer_forward(tmr, tmr->base->get_time(),
441 tsk->signal->it_real_incr);
442 hrtimer_restart(tmr);
451 if (unlikely(sig_kernel_stop(signr))) {
453 * Set a marker that we have dequeued a stop signal. Our
454 * caller might release the siglock and then the pending
455 * stop signal it is about to process is no longer in the
456 * pending bitmasks, but must still be cleared by a SIGCONT
457 * (and overruled by a SIGKILL). So those cases clear this
458 * shared flag after we've set it. Note that this flag may
459 * remain set after the signal we return is ignored or
460 * handled. That doesn't matter because its only purpose
461 * is to alert stop-signal processing code when another
462 * processor has come along and cleared the flag.
464 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
466 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
468 * Release the siglock to ensure proper locking order
469 * of timer locks outside of siglocks. Note, we leave
470 * irqs disabled here, since the posix-timers code is
471 * about to disable them again anyway.
473 spin_unlock(&tsk->sighand->siglock);
474 do_schedule_next_timer(info);
475 spin_lock(&tsk->sighand->siglock);
481 * Tell a process that it has a new active signal..
483 * NOTE! we rely on the previous spin_lock to
484 * lock interrupts for us! We can only be called with
485 * "siglock" held, and the local interrupt must
486 * have been disabled when that got acquired!
488 * No need to set need_resched since signal event passing
489 * goes through ->blocked
491 void signal_wake_up(struct task_struct *t, int resume)
495 set_tsk_thread_flag(t, TIF_SIGPENDING);
498 * For SIGKILL, we want to wake it up in the stopped/traced/killable
499 * case. We don't check t->state here because there is a race with it
500 * executing another processor and just now entering stopped state.
501 * By using wake_up_state, we ensure the process will wake up and
502 * handle its death signal.
504 mask = TASK_INTERRUPTIBLE;
506 mask |= TASK_WAKEKILL;
507 if (!wake_up_state(t, mask))
512 * Remove signals in mask from the pending set and queue.
513 * Returns 1 if any signals were found.
515 * All callers must be holding the siglock.
517 * This version takes a sigset mask and looks at all signals,
518 * not just those in the first mask word.
520 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
522 struct sigqueue *q, *n;
525 sigandsets(&m, mask, &s->signal);
526 if (sigisemptyset(&m))
529 signandsets(&s->signal, &s->signal, mask);
530 list_for_each_entry_safe(q, n, &s->list, list) {
531 if (sigismember(mask, q->info.si_signo)) {
532 list_del_init(&q->list);
539 * Remove signals in mask from the pending set and queue.
540 * Returns 1 if any signals were found.
542 * All callers must be holding the siglock.
544 static int rm_from_queue(unsigned long mask, struct sigpending *s)
546 struct sigqueue *q, *n;
548 if (!sigtestsetmask(&s->signal, mask))
551 sigdelsetmask(&s->signal, mask);
552 list_for_each_entry_safe(q, n, &s->list, list) {
553 if (q->info.si_signo < SIGRTMIN &&
554 (mask & sigmask(q->info.si_signo))) {
555 list_del_init(&q->list);
563 * Bad permissions for sending the signal
565 static int check_kill_permission(int sig, struct siginfo *info,
566 struct task_struct *t)
571 if (!valid_signal(sig))
574 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
577 error = audit_signal_info(sig, t); /* Let audit system see the signal */
581 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
582 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
583 !capable(CAP_KILL)) {
586 sid = task_session(t);
588 * We don't return the error if sid == NULL. The
589 * task was unhashed, the caller must notice this.
591 if (!sid || sid == task_session(current))
598 return security_task_kill(t, info, sig, 0);
602 * Handle magic process-wide effects of stop/continue signals. Unlike
603 * the signal actions, these happen immediately at signal-generation
604 * time regardless of blocking, ignoring, or handling. This does the
605 * actual continuing for SIGCONT, but not the actual stopping for stop
606 * signals. The process stop is done as a signal action for SIG_DFL.
608 * Returns true if the signal should be actually delivered, otherwise
609 * it should be dropped.
611 static int prepare_signal(int sig, struct task_struct *p)
613 struct signal_struct *signal = p->signal;
614 struct task_struct *t;
616 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
618 * The process is in the middle of dying, nothing to do.
620 } else if (sig_kernel_stop(sig)) {
622 * This is a stop signal. Remove SIGCONT from all queues.
624 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
627 rm_from_queue(sigmask(SIGCONT), &t->pending);
628 } while_each_thread(p, t);
629 } else if (sig == SIGCONT) {
632 * Remove all stop signals from all queues,
633 * and wake all threads.
635 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
639 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
641 * If there is a handler for SIGCONT, we must make
642 * sure that no thread returns to user mode before
643 * we post the signal, in case it was the only
644 * thread eligible to run the signal handler--then
645 * it must not do anything between resuming and
646 * running the handler. With the TIF_SIGPENDING
647 * flag set, the thread will pause and acquire the
648 * siglock that we hold now and until we've queued
649 * the pending signal.
651 * Wake up the stopped thread _after_ setting
654 state = __TASK_STOPPED;
655 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
656 set_tsk_thread_flag(t, TIF_SIGPENDING);
657 state |= TASK_INTERRUPTIBLE;
659 wake_up_state(t, state);
660 } while_each_thread(p, t);
663 * Notify the parent with CLD_CONTINUED if we were stopped.
665 * If we were in the middle of a group stop, we pretend it
666 * was already finished, and then continued. Since SIGCHLD
667 * doesn't queue we report only CLD_STOPPED, as if the next
668 * CLD_CONTINUED was dropped.
671 if (signal->flags & SIGNAL_STOP_STOPPED)
672 why |= SIGNAL_CLD_CONTINUED;
673 else if (signal->group_stop_count)
674 why |= SIGNAL_CLD_STOPPED;
678 * The first thread which returns from finish_stop()
679 * will take ->siglock, notice SIGNAL_CLD_MASK, and
680 * notify its parent. See get_signal_to_deliver().
682 signal->flags = why | SIGNAL_STOP_CONTINUED;
683 signal->group_stop_count = 0;
684 signal->group_exit_code = 0;
687 * We are not stopped, but there could be a stop
688 * signal in the middle of being processed after
689 * being removed from the queue. Clear that too.
691 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
695 return !sig_ignored(p, sig);
699 * Test if P wants to take SIG. After we've checked all threads with this,
700 * it's equivalent to finding no threads not blocking SIG. Any threads not
701 * blocking SIG were ruled out because they are not running and already
702 * have pending signals. Such threads will dequeue from the shared queue
703 * as soon as they're available, so putting the signal on the shared queue
704 * will be equivalent to sending it to one such thread.
706 static inline int wants_signal(int sig, struct task_struct *p)
708 if (sigismember(&p->blocked, sig))
710 if (p->flags & PF_EXITING)
714 if (task_is_stopped_or_traced(p))
716 return task_curr(p) || !signal_pending(p);
719 static void complete_signal(int sig, struct task_struct *p, int group)
721 struct signal_struct *signal = p->signal;
722 struct task_struct *t;
725 * Now find a thread we can wake up to take the signal off the queue.
727 * If the main thread wants the signal, it gets first crack.
728 * Probably the least surprising to the average bear.
730 if (wants_signal(sig, p))
732 else if (!group || thread_group_empty(p))
734 * There is just one thread and it does not need to be woken.
735 * It will dequeue unblocked signals before it runs again.
740 * Otherwise try to find a suitable thread.
742 t = signal->curr_target;
743 while (!wants_signal(sig, t)) {
745 if (t == signal->curr_target)
747 * No thread needs to be woken.
748 * Any eligible threads will see
749 * the signal in the queue soon.
753 signal->curr_target = t;
757 * Found a killable thread. If the signal will be fatal,
758 * then start taking the whole group down immediately.
760 if (sig_fatal(p, sig) &&
761 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
762 !sigismember(&t->real_blocked, sig) &&
764 !tracehook_consider_fatal_signal(t, sig, SIG_DFL))) {
766 * This signal will be fatal to the whole group.
768 if (!sig_kernel_coredump(sig)) {
770 * Start a group exit and wake everybody up.
771 * This way we don't have other threads
772 * running and doing things after a slower
773 * thread has the fatal signal pending.
775 signal->flags = SIGNAL_GROUP_EXIT;
776 signal->group_exit_code = sig;
777 signal->group_stop_count = 0;
780 sigaddset(&t->pending.signal, SIGKILL);
781 signal_wake_up(t, 1);
782 } while_each_thread(p, t);
788 * The signal is already in the shared-pending queue.
789 * Tell the chosen thread to wake up and dequeue it.
791 signal_wake_up(t, sig == SIGKILL);
795 static inline int legacy_queue(struct sigpending *signals, int sig)
797 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
800 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
803 struct sigpending *pending;
806 assert_spin_locked(&t->sighand->siglock);
807 if (!prepare_signal(sig, t))
810 pending = group ? &t->signal->shared_pending : &t->pending;
812 * Short-circuit ignored signals and support queuing
813 * exactly one non-rt signal, so that we can get more
814 * detailed information about the cause of the signal.
816 if (legacy_queue(pending, sig))
819 * fast-pathed signals for kernel-internal things like SIGSTOP
822 if (info == SEND_SIG_FORCED)
825 /* Real-time signals must be queued if sent by sigqueue, or
826 some other real-time mechanism. It is implementation
827 defined whether kill() does so. We attempt to do so, on
828 the principle of least surprise, but since kill is not
829 allowed to fail with EAGAIN when low on memory we just
830 make sure at least one signal gets delivered and don't
831 pass on the info struct. */
833 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
834 (is_si_special(info) ||
835 info->si_code >= 0)));
837 list_add_tail(&q->list, &pending->list);
838 switch ((unsigned long) info) {
839 case (unsigned long) SEND_SIG_NOINFO:
840 q->info.si_signo = sig;
841 q->info.si_errno = 0;
842 q->info.si_code = SI_USER;
843 q->info.si_pid = task_pid_vnr(current);
844 q->info.si_uid = current->uid;
846 case (unsigned long) SEND_SIG_PRIV:
847 q->info.si_signo = sig;
848 q->info.si_errno = 0;
849 q->info.si_code = SI_KERNEL;
854 copy_siginfo(&q->info, info);
857 } else if (!is_si_special(info)) {
858 if (sig >= SIGRTMIN && info->si_code != SI_USER)
860 * Queue overflow, abort. We may abort if the signal was rt
861 * and sent by user using something other than kill().
867 signalfd_notify(t, sig);
868 sigaddset(&pending->signal, sig);
869 complete_signal(sig, t, group);
873 int print_fatal_signals;
875 static void print_fatal_signal(struct pt_regs *regs, int signr)
877 printk("%s/%d: potentially unexpected fatal signal %d.\n",
878 current->comm, task_pid_nr(current), signr);
880 #if defined(__i386__) && !defined(__arch_um__)
881 printk("code at %08lx: ", regs->ip);
884 for (i = 0; i < 16; i++) {
887 __get_user(insn, (unsigned char *)(regs->ip + i));
888 printk("%02x ", insn);
896 static int __init setup_print_fatal_signals(char *str)
898 get_option (&str, &print_fatal_signals);
903 __setup("print-fatal-signals=", setup_print_fatal_signals);
906 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
908 return send_signal(sig, info, p, 1);
912 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
914 return send_signal(sig, info, t, 0);
918 * Force a signal that the process can't ignore: if necessary
919 * we unblock the signal and change any SIG_IGN to SIG_DFL.
921 * Note: If we unblock the signal, we always reset it to SIG_DFL,
922 * since we do not want to have a signal handler that was blocked
923 * be invoked when user space had explicitly blocked it.
925 * We don't want to have recursive SIGSEGV's etc, for example,
926 * that is why we also clear SIGNAL_UNKILLABLE.
929 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
931 unsigned long int flags;
932 int ret, blocked, ignored;
933 struct k_sigaction *action;
935 spin_lock_irqsave(&t->sighand->siglock, flags);
936 action = &t->sighand->action[sig-1];
937 ignored = action->sa.sa_handler == SIG_IGN;
938 blocked = sigismember(&t->blocked, sig);
939 if (blocked || ignored) {
940 action->sa.sa_handler = SIG_DFL;
942 sigdelset(&t->blocked, sig);
943 recalc_sigpending_and_wake(t);
946 if (action->sa.sa_handler == SIG_DFL)
947 t->signal->flags &= ~SIGNAL_UNKILLABLE;
948 ret = specific_send_sig_info(sig, info, t);
949 spin_unlock_irqrestore(&t->sighand->siglock, flags);
955 force_sig_specific(int sig, struct task_struct *t)
957 force_sig_info(sig, SEND_SIG_FORCED, t);
961 * Nuke all other threads in the group.
963 void zap_other_threads(struct task_struct *p)
965 struct task_struct *t;
967 p->signal->group_stop_count = 0;
969 for (t = next_thread(p); t != p; t = next_thread(t)) {
971 * Don't bother with already dead threads
976 /* SIGKILL will be handled before any pending SIGSTOP */
977 sigaddset(&t->pending.signal, SIGKILL);
978 signal_wake_up(t, 1);
982 int __fatal_signal_pending(struct task_struct *tsk)
984 return sigismember(&tsk->pending.signal, SIGKILL);
986 EXPORT_SYMBOL(__fatal_signal_pending);
988 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
990 struct sighand_struct *sighand;
994 sighand = rcu_dereference(tsk->sighand);
995 if (unlikely(sighand == NULL))
998 spin_lock_irqsave(&sighand->siglock, *flags);
999 if (likely(sighand == tsk->sighand))
1001 spin_unlock_irqrestore(&sighand->siglock, *flags);
1008 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1010 unsigned long flags;
1013 ret = check_kill_permission(sig, info, p);
1017 if (lock_task_sighand(p, &flags)) {
1018 ret = __group_send_sig_info(sig, info, p);
1019 unlock_task_sighand(p, &flags);
1027 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1028 * control characters do (^C, ^Z etc)
1031 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1033 struct task_struct *p = NULL;
1034 int retval, success;
1038 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1039 int err = group_send_sig_info(sig, info, p);
1042 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1043 return success ? 0 : retval;
1046 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1049 struct task_struct *p;
1053 p = pid_task(pid, PIDTYPE_PID);
1055 error = group_send_sig_info(sig, info, p);
1056 if (unlikely(error == -ESRCH))
1058 * The task was unhashed in between, try again.
1059 * If it is dead, pid_task() will return NULL,
1060 * if we race with de_thread() it will find the
1071 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1075 error = kill_pid_info(sig, info, find_vpid(pid));
1080 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1081 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1082 uid_t uid, uid_t euid, u32 secid)
1085 struct task_struct *p;
1087 if (!valid_signal(sig))
1090 read_lock(&tasklist_lock);
1091 p = pid_task(pid, PIDTYPE_PID);
1096 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1097 && (euid != p->suid) && (euid != p->uid)
1098 && (uid != p->suid) && (uid != p->uid)) {
1102 ret = security_task_kill(p, info, sig, secid);
1105 if (sig && p->sighand) {
1106 unsigned long flags;
1107 spin_lock_irqsave(&p->sighand->siglock, flags);
1108 ret = __group_send_sig_info(sig, info, p);
1109 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1112 read_unlock(&tasklist_lock);
1115 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1118 * kill_something_info() interprets pid in interesting ways just like kill(2).
1120 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1121 * is probably wrong. Should make it like BSD or SYSV.
1124 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1130 ret = kill_pid_info(sig, info, find_vpid(pid));
1135 read_lock(&tasklist_lock);
1137 ret = __kill_pgrp_info(sig, info,
1138 pid ? find_vpid(-pid) : task_pgrp(current));
1140 int retval = 0, count = 0;
1141 struct task_struct * p;
1143 for_each_process(p) {
1144 if (p->pid > 1 && !same_thread_group(p, current)) {
1145 int err = group_send_sig_info(sig, info, p);
1151 ret = count ? retval : -ESRCH;
1153 read_unlock(&tasklist_lock);
1159 * These are for backward compatibility with the rest of the kernel source.
1163 * The caller must ensure the task can't exit.
1166 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1169 unsigned long flags;
1172 * Make sure legacy kernel users don't send in bad values
1173 * (normal paths check this in check_kill_permission).
1175 if (!valid_signal(sig))
1178 spin_lock_irqsave(&p->sighand->siglock, flags);
1179 ret = specific_send_sig_info(sig, info, p);
1180 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1184 #define __si_special(priv) \
1185 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1188 send_sig(int sig, struct task_struct *p, int priv)
1190 return send_sig_info(sig, __si_special(priv), p);
1194 force_sig(int sig, struct task_struct *p)
1196 force_sig_info(sig, SEND_SIG_PRIV, p);
1200 * When things go south during signal handling, we
1201 * will force a SIGSEGV. And if the signal that caused
1202 * the problem was already a SIGSEGV, we'll want to
1203 * make sure we don't even try to deliver the signal..
1206 force_sigsegv(int sig, struct task_struct *p)
1208 if (sig == SIGSEGV) {
1209 unsigned long flags;
1210 spin_lock_irqsave(&p->sighand->siglock, flags);
1211 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1212 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1214 force_sig(SIGSEGV, p);
1218 int kill_pgrp(struct pid *pid, int sig, int priv)
1222 read_lock(&tasklist_lock);
1223 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1224 read_unlock(&tasklist_lock);
1228 EXPORT_SYMBOL(kill_pgrp);
1230 int kill_pid(struct pid *pid, int sig, int priv)
1232 return kill_pid_info(sig, __si_special(priv), pid);
1234 EXPORT_SYMBOL(kill_pid);
1237 * These functions support sending signals using preallocated sigqueue
1238 * structures. This is needed "because realtime applications cannot
1239 * afford to lose notifications of asynchronous events, like timer
1240 * expirations or I/O completions". In the case of Posix Timers
1241 * we allocate the sigqueue structure from the timer_create. If this
1242 * allocation fails we are able to report the failure to the application
1243 * with an EAGAIN error.
1246 struct sigqueue *sigqueue_alloc(void)
1250 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1251 q->flags |= SIGQUEUE_PREALLOC;
1255 void sigqueue_free(struct sigqueue *q)
1257 unsigned long flags;
1258 spinlock_t *lock = ¤t->sighand->siglock;
1260 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1262 * We must hold ->siglock while testing q->list
1263 * to serialize with collect_signal() or with
1264 * __exit_signal()->flush_sigqueue().
1266 spin_lock_irqsave(lock, flags);
1267 q->flags &= ~SIGQUEUE_PREALLOC;
1269 * If it is queued it will be freed when dequeued,
1270 * like the "regular" sigqueue.
1272 if (!list_empty(&q->list))
1274 spin_unlock_irqrestore(lock, flags);
1280 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1282 int sig = q->info.si_signo;
1283 struct sigpending *pending;
1284 unsigned long flags;
1287 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1290 if (!likely(lock_task_sighand(t, &flags)))
1293 ret = 1; /* the signal is ignored */
1294 if (!prepare_signal(sig, t))
1298 if (unlikely(!list_empty(&q->list))) {
1300 * If an SI_TIMER entry is already queue just increment
1301 * the overrun count.
1303 BUG_ON(q->info.si_code != SI_TIMER);
1304 q->info.si_overrun++;
1307 q->info.si_overrun = 0;
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.
1333 * Returns -1 if our parent ignored us and so we've switched to
1334 * self-reaping, or else @sig.
1336 int do_notify_parent(struct task_struct *tsk, int sig)
1338 struct siginfo info;
1339 unsigned long flags;
1340 struct sighand_struct *psig;
1345 /* do_notify_parent_cldstop should have been called instead. */
1346 BUG_ON(task_is_stopped_or_traced(tsk));
1348 BUG_ON(!tsk->ptrace &&
1349 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1351 info.si_signo = sig;
1354 * we are under tasklist_lock here so our parent is tied to
1355 * us and cannot exit and release its namespace.
1357 * the only it can is to switch its nsproxy with sys_unshare,
1358 * bu uncharing pid namespaces is not allowed, so we'll always
1359 * see relevant namespace
1361 * write_lock() currently calls preempt_disable() which is the
1362 * same as rcu_read_lock(), but according to Oleg, this is not
1363 * correct to rely on this
1366 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1369 info.si_uid = tsk->uid;
1371 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1372 tsk->signal->utime));
1373 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1374 tsk->signal->stime));
1376 info.si_status = tsk->exit_code & 0x7f;
1377 if (tsk->exit_code & 0x80)
1378 info.si_code = CLD_DUMPED;
1379 else if (tsk->exit_code & 0x7f)
1380 info.si_code = CLD_KILLED;
1382 info.si_code = CLD_EXITED;
1383 info.si_status = tsk->exit_code >> 8;
1386 psig = tsk->parent->sighand;
1387 spin_lock_irqsave(&psig->siglock, flags);
1388 if (!tsk->ptrace && sig == SIGCHLD &&
1389 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1390 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1392 * We are exiting and our parent doesn't care. POSIX.1
1393 * defines special semantics for setting SIGCHLD to SIG_IGN
1394 * or setting the SA_NOCLDWAIT flag: we should be reaped
1395 * automatically and not left for our parent's wait4 call.
1396 * Rather than having the parent do it as a magic kind of
1397 * signal handler, we just set this to tell do_exit that we
1398 * can be cleaned up without becoming a zombie. Note that
1399 * we still call __wake_up_parent in this case, because a
1400 * blocked sys_wait4 might now return -ECHILD.
1402 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1403 * is implementation-defined: we do (if you don't want
1404 * it, just use SIG_IGN instead).
1406 ret = tsk->exit_signal = -1;
1407 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1410 if (valid_signal(sig) && sig > 0)
1411 __group_send_sig_info(sig, &info, tsk->parent);
1412 __wake_up_parent(tsk, tsk->parent);
1413 spin_unlock_irqrestore(&psig->siglock, flags);
1418 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1420 struct siginfo info;
1421 unsigned long flags;
1422 struct task_struct *parent;
1423 struct sighand_struct *sighand;
1425 if (tsk->ptrace & PT_PTRACED)
1426 parent = tsk->parent;
1428 tsk = tsk->group_leader;
1429 parent = tsk->real_parent;
1432 info.si_signo = SIGCHLD;
1435 * see comment in do_notify_parent() abot the following 3 lines
1438 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1441 info.si_uid = tsk->uid;
1443 info.si_utime = cputime_to_clock_t(tsk->utime);
1444 info.si_stime = cputime_to_clock_t(tsk->stime);
1449 info.si_status = SIGCONT;
1452 info.si_status = tsk->signal->group_exit_code & 0x7f;
1455 info.si_status = tsk->exit_code & 0x7f;
1461 sighand = parent->sighand;
1462 spin_lock_irqsave(&sighand->siglock, flags);
1463 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1464 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1465 __group_send_sig_info(SIGCHLD, &info, parent);
1467 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1469 __wake_up_parent(tsk, parent);
1470 spin_unlock_irqrestore(&sighand->siglock, flags);
1473 static inline int may_ptrace_stop(void)
1475 if (!likely(current->ptrace & PT_PTRACED))
1478 * Are we in the middle of do_coredump?
1479 * If so and our tracer is also part of the coredump stopping
1480 * is a deadlock situation, and pointless because our tracer
1481 * is dead so don't allow us to stop.
1482 * If SIGKILL was already sent before the caller unlocked
1483 * ->siglock we must see ->core_state != NULL. Otherwise it
1484 * is safe to enter schedule().
1486 if (unlikely(current->mm->core_state) &&
1487 unlikely(current->mm == current->parent->mm))
1494 * Return nonzero if there is a SIGKILL that should be waking us up.
1495 * Called with the siglock held.
1497 static int sigkill_pending(struct task_struct *tsk)
1499 return sigismember(&tsk->pending.signal, SIGKILL) ||
1500 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1504 * This must be called with current->sighand->siglock held.
1506 * This should be the path for all ptrace stops.
1507 * We always set current->last_siginfo while stopped here.
1508 * That makes it a way to test a stopped process for
1509 * being ptrace-stopped vs being job-control-stopped.
1511 * If we actually decide not to stop at all because the tracer
1512 * is gone, we keep current->exit_code unless clear_code.
1514 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1516 if (arch_ptrace_stop_needed(exit_code, info)) {
1518 * The arch code has something special to do before a
1519 * ptrace stop. This is allowed to block, e.g. for faults
1520 * on user stack pages. We can't keep the siglock while
1521 * calling arch_ptrace_stop, so we must release it now.
1522 * To preserve proper semantics, we must do this before
1523 * any signal bookkeeping like checking group_stop_count.
1524 * Meanwhile, a SIGKILL could come in before we retake the
1525 * siglock. That must prevent us from sleeping in TASK_TRACED.
1526 * So after regaining the lock, we must check for SIGKILL.
1528 spin_unlock_irq(¤t->sighand->siglock);
1529 arch_ptrace_stop(exit_code, info);
1530 spin_lock_irq(¤t->sighand->siglock);
1531 if (sigkill_pending(current))
1536 * If there is a group stop in progress,
1537 * we must participate in the bookkeeping.
1539 if (current->signal->group_stop_count > 0)
1540 --current->signal->group_stop_count;
1542 current->last_siginfo = info;
1543 current->exit_code = exit_code;
1545 /* Let the debugger run. */
1546 __set_current_state(TASK_TRACED);
1547 spin_unlock_irq(¤t->sighand->siglock);
1548 read_lock(&tasklist_lock);
1549 if (may_ptrace_stop()) {
1550 do_notify_parent_cldstop(current, CLD_TRAPPED);
1551 read_unlock(&tasklist_lock);
1555 * By the time we got the lock, our tracer went away.
1556 * Don't drop the lock yet, another tracer may come.
1558 __set_current_state(TASK_RUNNING);
1560 current->exit_code = 0;
1561 read_unlock(&tasklist_lock);
1565 * While in TASK_TRACED, we were considered "frozen enough".
1566 * Now that we woke up, it's crucial if we're supposed to be
1567 * frozen that we freeze now before running anything substantial.
1572 * We are back. Now reacquire the siglock before touching
1573 * last_siginfo, so that we are sure to have synchronized with
1574 * any signal-sending on another CPU that wants to examine it.
1576 spin_lock_irq(¤t->sighand->siglock);
1577 current->last_siginfo = NULL;
1580 * Queued signals ignored us while we were stopped for tracing.
1581 * So check for any that we should take before resuming user mode.
1582 * This sets TIF_SIGPENDING, but never clears it.
1584 recalc_sigpending_tsk(current);
1587 void ptrace_notify(int exit_code)
1591 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1593 memset(&info, 0, sizeof info);
1594 info.si_signo = SIGTRAP;
1595 info.si_code = exit_code;
1596 info.si_pid = task_pid_vnr(current);
1597 info.si_uid = current->uid;
1599 /* Let the debugger run. */
1600 spin_lock_irq(¤t->sighand->siglock);
1601 ptrace_stop(exit_code, 1, &info);
1602 spin_unlock_irq(¤t->sighand->siglock);
1606 finish_stop(int stop_count)
1609 * If there are no other threads in the group, or if there is
1610 * a group stop in progress and we are the last to stop,
1611 * report to the parent. When ptraced, every thread reports itself.
1613 if (tracehook_notify_jctl(stop_count == 0, CLD_STOPPED)) {
1614 read_lock(&tasklist_lock);
1615 do_notify_parent_cldstop(current, CLD_STOPPED);
1616 read_unlock(&tasklist_lock);
1621 } while (try_to_freeze());
1623 * Now we don't run again until continued.
1625 current->exit_code = 0;
1629 * This performs the stopping for SIGSTOP and other stop signals.
1630 * We have to stop all threads in the thread group.
1631 * Returns nonzero if we've actually stopped and released the siglock.
1632 * Returns zero if we didn't stop and still hold the siglock.
1634 static int do_signal_stop(int signr)
1636 struct signal_struct *sig = current->signal;
1639 if (sig->group_stop_count > 0) {
1641 * There is a group stop in progress. We don't need to
1642 * start another one.
1644 stop_count = --sig->group_stop_count;
1646 struct task_struct *t;
1648 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1649 unlikely(signal_group_exit(sig)))
1652 * There is no group stop already in progress.
1653 * We must initiate one now.
1655 sig->group_exit_code = signr;
1658 for (t = next_thread(current); t != current; t = next_thread(t))
1660 * Setting state to TASK_STOPPED for a group
1661 * stop is always done with the siglock held,
1662 * so this check has no races.
1664 if (!(t->flags & PF_EXITING) &&
1665 !task_is_stopped_or_traced(t)) {
1667 signal_wake_up(t, 0);
1669 sig->group_stop_count = stop_count;
1672 if (stop_count == 0)
1673 sig->flags = SIGNAL_STOP_STOPPED;
1674 current->exit_code = sig->group_exit_code;
1675 __set_current_state(TASK_STOPPED);
1677 spin_unlock_irq(¤t->sighand->siglock);
1678 finish_stop(stop_count);
1682 static int ptrace_signal(int signr, siginfo_t *info,
1683 struct pt_regs *regs, void *cookie)
1685 if (!(current->ptrace & PT_PTRACED))
1688 ptrace_signal_deliver(regs, cookie);
1690 /* Let the debugger run. */
1691 ptrace_stop(signr, 0, info);
1693 /* We're back. Did the debugger cancel the sig? */
1694 signr = current->exit_code;
1698 current->exit_code = 0;
1700 /* Update the siginfo structure if the signal has
1701 changed. If the debugger wanted something
1702 specific in the siginfo structure then it should
1703 have updated *info via PTRACE_SETSIGINFO. */
1704 if (signr != info->si_signo) {
1705 info->si_signo = signr;
1707 info->si_code = SI_USER;
1708 info->si_pid = task_pid_vnr(current->parent);
1709 info->si_uid = current->parent->uid;
1712 /* If the (new) signal is now blocked, requeue it. */
1713 if (sigismember(¤t->blocked, signr)) {
1714 specific_send_sig_info(signr, info, current);
1721 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1722 struct pt_regs *regs, void *cookie)
1724 struct sighand_struct *sighand = current->sighand;
1725 struct signal_struct *signal = current->signal;
1730 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1731 * While in TASK_STOPPED, we were considered "frozen enough".
1732 * Now that we woke up, it's crucial if we're supposed to be
1733 * frozen that we freeze now before running anything substantial.
1737 spin_lock_irq(&sighand->siglock);
1739 * Every stopped thread goes here after wakeup. Check to see if
1740 * we should notify the parent, prepare_signal(SIGCONT) encodes
1741 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1743 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1744 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1745 ? CLD_CONTINUED : CLD_STOPPED;
1746 signal->flags &= ~SIGNAL_CLD_MASK;
1747 spin_unlock_irq(&sighand->siglock);
1749 if (unlikely(!tracehook_notify_jctl(1, why)))
1752 read_lock(&tasklist_lock);
1753 do_notify_parent_cldstop(current->group_leader, why);
1754 read_unlock(&tasklist_lock);
1759 struct k_sigaction *ka;
1761 if (unlikely(signal->group_stop_count > 0) &&
1766 * Tracing can induce an artifical signal and choose sigaction.
1767 * The return value in @signr determines the default action,
1768 * but @info->si_signo is the signal number we will report.
1770 signr = tracehook_get_signal(current, regs, info, return_ka);
1771 if (unlikely(signr < 0))
1773 if (unlikely(signr != 0))
1776 signr = dequeue_signal(current, ¤t->blocked,
1780 break; /* will return 0 */
1782 if (signr != SIGKILL) {
1783 signr = ptrace_signal(signr, info,
1789 ka = &sighand->action[signr-1];
1792 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1794 if (ka->sa.sa_handler != SIG_DFL) {
1795 /* Run the handler. */
1798 if (ka->sa.sa_flags & SA_ONESHOT)
1799 ka->sa.sa_handler = SIG_DFL;
1801 break; /* will return non-zero "signr" value */
1805 * Now we are doing the default action for this signal.
1807 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1811 * Global init gets no signals it doesn't want.
1813 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1814 !signal_group_exit(signal))
1817 if (sig_kernel_stop(signr)) {
1819 * The default action is to stop all threads in
1820 * the thread group. The job control signals
1821 * do nothing in an orphaned pgrp, but SIGSTOP
1822 * always works. Note that siglock needs to be
1823 * dropped during the call to is_orphaned_pgrp()
1824 * because of lock ordering with tasklist_lock.
1825 * This allows an intervening SIGCONT to be posted.
1826 * We need to check for that and bail out if necessary.
1828 if (signr != SIGSTOP) {
1829 spin_unlock_irq(&sighand->siglock);
1831 /* signals can be posted during this window */
1833 if (is_current_pgrp_orphaned())
1836 spin_lock_irq(&sighand->siglock);
1839 if (likely(do_signal_stop(info->si_signo))) {
1840 /* It released the siglock. */
1845 * We didn't actually stop, due to a race
1846 * with SIGCONT or something like that.
1851 spin_unlock_irq(&sighand->siglock);
1854 * Anything else is fatal, maybe with a core dump.
1856 current->flags |= PF_SIGNALED;
1858 if (sig_kernel_coredump(signr)) {
1859 if (print_fatal_signals)
1860 print_fatal_signal(regs, info->si_signo);
1862 * If it was able to dump core, this kills all
1863 * other threads in the group and synchronizes with
1864 * their demise. If we lost the race with another
1865 * thread getting here, it set group_exit_code
1866 * first and our do_group_exit call below will use
1867 * that value and ignore the one we pass it.
1869 do_coredump(info->si_signo, info->si_signo, regs);
1873 * Death signals, no core dump.
1875 do_group_exit(info->si_signo);
1878 spin_unlock_irq(&sighand->siglock);
1882 void exit_signals(struct task_struct *tsk)
1885 struct task_struct *t;
1887 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1888 tsk->flags |= PF_EXITING;
1892 spin_lock_irq(&tsk->sighand->siglock);
1894 * From now this task is not visible for group-wide signals,
1895 * see wants_signal(), do_signal_stop().
1897 tsk->flags |= PF_EXITING;
1898 if (!signal_pending(tsk))
1901 /* It could be that __group_complete_signal() choose us to
1902 * notify about group-wide signal. Another thread should be
1903 * woken now to take the signal since we will not.
1905 for (t = tsk; (t = next_thread(t)) != tsk; )
1906 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1907 recalc_sigpending_and_wake(t);
1909 if (unlikely(tsk->signal->group_stop_count) &&
1910 !--tsk->signal->group_stop_count) {
1911 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1915 spin_unlock_irq(&tsk->sighand->siglock);
1917 if (unlikely(group_stop) && tracehook_notify_jctl(1, CLD_STOPPED)) {
1918 read_lock(&tasklist_lock);
1919 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1920 read_unlock(&tasklist_lock);
1924 EXPORT_SYMBOL(recalc_sigpending);
1925 EXPORT_SYMBOL_GPL(dequeue_signal);
1926 EXPORT_SYMBOL(flush_signals);
1927 EXPORT_SYMBOL(force_sig);
1928 EXPORT_SYMBOL(send_sig);
1929 EXPORT_SYMBOL(send_sig_info);
1930 EXPORT_SYMBOL(sigprocmask);
1931 EXPORT_SYMBOL(block_all_signals);
1932 EXPORT_SYMBOL(unblock_all_signals);
1936 * System call entry points.
1939 asmlinkage long sys_restart_syscall(void)
1941 struct restart_block *restart = ¤t_thread_info()->restart_block;
1942 return restart->fn(restart);
1945 long do_no_restart_syscall(struct restart_block *param)
1951 * We don't need to get the kernel lock - this is all local to this
1952 * particular thread.. (and that's good, because this is _heavily_
1953 * used by various programs)
1957 * This is also useful for kernel threads that want to temporarily
1958 * (or permanently) block certain signals.
1960 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1961 * interface happily blocks "unblockable" signals like SIGKILL
1964 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1968 spin_lock_irq(¤t->sighand->siglock);
1970 *oldset = current->blocked;
1975 sigorsets(¤t->blocked, ¤t->blocked, set);
1978 signandsets(¤t->blocked, ¤t->blocked, set);
1981 current->blocked = *set;
1986 recalc_sigpending();
1987 spin_unlock_irq(¤t->sighand->siglock);
1993 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1995 int error = -EINVAL;
1996 sigset_t old_set, new_set;
1998 /* XXX: Don't preclude handling different sized sigset_t's. */
1999 if (sigsetsize != sizeof(sigset_t))
2004 if (copy_from_user(&new_set, set, sizeof(*set)))
2006 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2008 error = sigprocmask(how, &new_set, &old_set);
2014 spin_lock_irq(¤t->sighand->siglock);
2015 old_set = current->blocked;
2016 spin_unlock_irq(¤t->sighand->siglock);
2020 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2028 long do_sigpending(void __user *set, unsigned long sigsetsize)
2030 long error = -EINVAL;
2033 if (sigsetsize > sizeof(sigset_t))
2036 spin_lock_irq(¤t->sighand->siglock);
2037 sigorsets(&pending, ¤t->pending.signal,
2038 ¤t->signal->shared_pending.signal);
2039 spin_unlock_irq(¤t->sighand->siglock);
2041 /* Outside the lock because only this thread touches it. */
2042 sigandsets(&pending, ¤t->blocked, &pending);
2045 if (!copy_to_user(set, &pending, sigsetsize))
2053 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2055 return do_sigpending(set, sigsetsize);
2058 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2060 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2064 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2066 if (from->si_code < 0)
2067 return __copy_to_user(to, from, sizeof(siginfo_t))
2070 * If you change siginfo_t structure, please be sure
2071 * this code is fixed accordingly.
2072 * Please remember to update the signalfd_copyinfo() function
2073 * inside fs/signalfd.c too, in case siginfo_t changes.
2074 * It should never copy any pad contained in the structure
2075 * to avoid security leaks, but must copy the generic
2076 * 3 ints plus the relevant union member.
2078 err = __put_user(from->si_signo, &to->si_signo);
2079 err |= __put_user(from->si_errno, &to->si_errno);
2080 err |= __put_user((short)from->si_code, &to->si_code);
2081 switch (from->si_code & __SI_MASK) {
2083 err |= __put_user(from->si_pid, &to->si_pid);
2084 err |= __put_user(from->si_uid, &to->si_uid);
2087 err |= __put_user(from->si_tid, &to->si_tid);
2088 err |= __put_user(from->si_overrun, &to->si_overrun);
2089 err |= __put_user(from->si_ptr, &to->si_ptr);
2092 err |= __put_user(from->si_band, &to->si_band);
2093 err |= __put_user(from->si_fd, &to->si_fd);
2096 err |= __put_user(from->si_addr, &to->si_addr);
2097 #ifdef __ARCH_SI_TRAPNO
2098 err |= __put_user(from->si_trapno, &to->si_trapno);
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_status, &to->si_status);
2105 err |= __put_user(from->si_utime, &to->si_utime);
2106 err |= __put_user(from->si_stime, &to->si_stime);
2108 case __SI_RT: /* This is not generated by the kernel as of now. */
2109 case __SI_MESGQ: /* But this is */
2110 err |= __put_user(from->si_pid, &to->si_pid);
2111 err |= __put_user(from->si_uid, &to->si_uid);
2112 err |= __put_user(from->si_ptr, &to->si_ptr);
2114 default: /* this is just in case for now ... */
2115 err |= __put_user(from->si_pid, &to->si_pid);
2116 err |= __put_user(from->si_uid, &to->si_uid);
2125 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2126 siginfo_t __user *uinfo,
2127 const struct timespec __user *uts,
2136 /* XXX: Don't preclude handling different sized sigset_t's. */
2137 if (sigsetsize != sizeof(sigset_t))
2140 if (copy_from_user(&these, uthese, sizeof(these)))
2144 * Invert the set of allowed signals to get those we
2147 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2151 if (copy_from_user(&ts, uts, sizeof(ts)))
2153 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2158 spin_lock_irq(¤t->sighand->siglock);
2159 sig = dequeue_signal(current, &these, &info);
2161 timeout = MAX_SCHEDULE_TIMEOUT;
2163 timeout = (timespec_to_jiffies(&ts)
2164 + (ts.tv_sec || ts.tv_nsec));
2167 /* None ready -- temporarily unblock those we're
2168 * interested while we are sleeping in so that we'll
2169 * be awakened when they arrive. */
2170 current->real_blocked = current->blocked;
2171 sigandsets(¤t->blocked, ¤t->blocked, &these);
2172 recalc_sigpending();
2173 spin_unlock_irq(¤t->sighand->siglock);
2175 timeout = schedule_timeout_interruptible(timeout);
2177 spin_lock_irq(¤t->sighand->siglock);
2178 sig = dequeue_signal(current, &these, &info);
2179 current->blocked = current->real_blocked;
2180 siginitset(¤t->real_blocked, 0);
2181 recalc_sigpending();
2184 spin_unlock_irq(¤t->sighand->siglock);
2189 if (copy_siginfo_to_user(uinfo, &info))
2202 sys_kill(pid_t pid, int sig)
2204 struct siginfo info;
2206 info.si_signo = sig;
2208 info.si_code = SI_USER;
2209 info.si_pid = task_tgid_vnr(current);
2210 info.si_uid = current->uid;
2212 return kill_something_info(sig, &info, pid);
2215 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2218 struct siginfo info;
2219 struct task_struct *p;
2220 unsigned long flags;
2223 info.si_signo = sig;
2225 info.si_code = SI_TKILL;
2226 info.si_pid = task_tgid_vnr(current);
2227 info.si_uid = current->uid;
2230 p = find_task_by_vpid(pid);
2231 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2232 error = check_kill_permission(sig, &info, p);
2234 * The null signal is a permissions and process existence
2235 * probe. No signal is actually delivered.
2237 * If lock_task_sighand() fails we pretend the task dies
2238 * after receiving the signal. The window is tiny, and the
2239 * signal is private anyway.
2241 if (!error && sig && lock_task_sighand(p, &flags)) {
2242 error = specific_send_sig_info(sig, &info, p);
2243 unlock_task_sighand(p, &flags);
2252 * sys_tgkill - send signal to one specific thread
2253 * @tgid: the thread group ID of the thread
2254 * @pid: the PID of the thread
2255 * @sig: signal to be sent
2257 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2258 * exists but it's not belonging to the target process anymore. This
2259 * method solves the problem of threads exiting and PIDs getting reused.
2261 asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig)
2263 /* This is only valid for single tasks */
2264 if (pid <= 0 || tgid <= 0)
2267 return do_tkill(tgid, pid, sig);
2271 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2274 sys_tkill(pid_t pid, int sig)
2276 /* This is only valid for single tasks */
2280 return do_tkill(0, pid, sig);
2284 sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo)
2288 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2291 /* Not even root can pretend to send signals from the kernel.
2292 Nor can they impersonate a kill(), which adds source info. */
2293 if (info.si_code >= 0)
2295 info.si_signo = sig;
2297 /* POSIX.1b doesn't mention process groups. */
2298 return kill_proc_info(sig, &info, pid);
2301 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2303 struct task_struct *t = current;
2304 struct k_sigaction *k;
2307 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2310 k = &t->sighand->action[sig-1];
2312 spin_lock_irq(¤t->sighand->siglock);
2317 sigdelsetmask(&act->sa.sa_mask,
2318 sigmask(SIGKILL) | sigmask(SIGSTOP));
2322 * "Setting a signal action to SIG_IGN for a signal that is
2323 * pending shall cause the pending signal to be discarded,
2324 * whether or not it is blocked."
2326 * "Setting a signal action to SIG_DFL for a signal that is
2327 * pending and whose default action is to ignore the signal
2328 * (for example, SIGCHLD), shall cause the pending signal to
2329 * be discarded, whether or not it is blocked"
2331 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2333 sigaddset(&mask, sig);
2334 rm_from_queue_full(&mask, &t->signal->shared_pending);
2336 rm_from_queue_full(&mask, &t->pending);
2338 } while (t != current);
2342 spin_unlock_irq(¤t->sighand->siglock);
2347 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2353 oss.ss_sp = (void __user *) current->sas_ss_sp;
2354 oss.ss_size = current->sas_ss_size;
2355 oss.ss_flags = sas_ss_flags(sp);
2364 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2365 || __get_user(ss_sp, &uss->ss_sp)
2366 || __get_user(ss_flags, &uss->ss_flags)
2367 || __get_user(ss_size, &uss->ss_size))
2371 if (on_sig_stack(sp))
2377 * Note - this code used to test ss_flags incorrectly
2378 * old code may have been written using ss_flags==0
2379 * to mean ss_flags==SS_ONSTACK (as this was the only
2380 * way that worked) - this fix preserves that older
2383 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2386 if (ss_flags == SS_DISABLE) {
2391 if (ss_size < MINSIGSTKSZ)
2395 current->sas_ss_sp = (unsigned long) ss_sp;
2396 current->sas_ss_size = ss_size;
2401 if (copy_to_user(uoss, &oss, sizeof(oss)))
2410 #ifdef __ARCH_WANT_SYS_SIGPENDING
2413 sys_sigpending(old_sigset_t __user *set)
2415 return do_sigpending(set, sizeof(*set));
2420 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2421 /* Some platforms have their own version with special arguments others
2422 support only sys_rt_sigprocmask. */
2425 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2428 old_sigset_t old_set, new_set;
2432 if (copy_from_user(&new_set, set, sizeof(*set)))
2434 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2436 spin_lock_irq(¤t->sighand->siglock);
2437 old_set = current->blocked.sig[0];
2445 sigaddsetmask(¤t->blocked, new_set);
2448 sigdelsetmask(¤t->blocked, new_set);
2451 current->blocked.sig[0] = new_set;
2455 recalc_sigpending();
2456 spin_unlock_irq(¤t->sighand->siglock);
2462 old_set = current->blocked.sig[0];
2465 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2472 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2474 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2476 sys_rt_sigaction(int sig,
2477 const struct sigaction __user *act,
2478 struct sigaction __user *oact,
2481 struct k_sigaction new_sa, old_sa;
2484 /* XXX: Don't preclude handling different sized sigset_t's. */
2485 if (sigsetsize != sizeof(sigset_t))
2489 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2493 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2496 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2502 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2504 #ifdef __ARCH_WANT_SYS_SGETMASK
2507 * For backwards compatibility. Functionality superseded by sigprocmask.
2513 return current->blocked.sig[0];
2517 sys_ssetmask(int newmask)
2521 spin_lock_irq(¤t->sighand->siglock);
2522 old = current->blocked.sig[0];
2524 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2526 recalc_sigpending();
2527 spin_unlock_irq(¤t->sighand->siglock);
2531 #endif /* __ARCH_WANT_SGETMASK */
2533 #ifdef __ARCH_WANT_SYS_SIGNAL
2535 * For backwards compatibility. Functionality superseded by sigaction.
2537 asmlinkage unsigned long
2538 sys_signal(int sig, __sighandler_t handler)
2540 struct k_sigaction new_sa, old_sa;
2543 new_sa.sa.sa_handler = handler;
2544 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2545 sigemptyset(&new_sa.sa.sa_mask);
2547 ret = do_sigaction(sig, &new_sa, &old_sa);
2549 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2551 #endif /* __ARCH_WANT_SYS_SIGNAL */
2553 #ifdef __ARCH_WANT_SYS_PAUSE
2558 current->state = TASK_INTERRUPTIBLE;
2560 return -ERESTARTNOHAND;
2565 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2566 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2570 /* XXX: Don't preclude handling different sized sigset_t's. */
2571 if (sigsetsize != sizeof(sigset_t))
2574 if (copy_from_user(&newset, unewset, sizeof(newset)))
2576 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2578 spin_lock_irq(¤t->sighand->siglock);
2579 current->saved_sigmask = current->blocked;
2580 current->blocked = newset;
2581 recalc_sigpending();
2582 spin_unlock_irq(¤t->sighand->siglock);
2584 current->state = TASK_INTERRUPTIBLE;
2586 set_restore_sigmask();
2587 return -ERESTARTNOHAND;
2589 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2591 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2596 void __init signals_init(void)
2598 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);