2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache *sigqueue_cachep;
42 static int __sig_ignored(struct task_struct *t, int sig)
46 /* Is it explicitly or implicitly ignored? */
48 handler = t->sighand->action[sig - 1].sa.sa_handler;
49 return handler == SIG_IGN ||
50 (handler == SIG_DFL && sig_kernel_ignore(sig));
53 static int sig_ignored(struct task_struct *t, int sig)
56 * Tracers always want to know about signals..
58 if (t->ptrace & PT_PTRACED)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
69 return __sig_ignored(t, sig);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
81 switch (_NSIG_WORDS) {
83 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
84 ready |= signal->sig[i] &~ blocked->sig[i];
87 case 4: ready = signal->sig[3] &~ blocked->sig[3];
88 ready |= signal->sig[2] &~ blocked->sig[2];
89 ready |= signal->sig[1] &~ blocked->sig[1];
90 ready |= signal->sig[0] &~ blocked->sig[0];
93 case 2: ready = signal->sig[1] &~ blocked->sig[1];
94 ready |= signal->sig[0] &~ blocked->sig[0];
97 case 1: ready = signal->sig[0] &~ blocked->sig[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct *t)
106 if (t->signal->group_stop_count > 0 ||
107 PENDING(&t->pending, &t->blocked) ||
108 PENDING(&t->signal->shared_pending, &t->blocked)) {
109 set_tsk_thread_flag(t, TIF_SIGPENDING);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct *t)
126 if (recalc_sigpending_tsk(t))
127 signal_wake_up(t, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current) && !freezing(current))
133 clear_thread_flag(TIF_SIGPENDING);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending *pending, sigset_t *mask)
141 unsigned long i, *s, *m, x;
144 s = pending->signal.sig;
146 switch (_NSIG_WORDS) {
148 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
149 if ((x = *s &~ *m) != 0) {
150 sig = ffz(~x) + i*_NSIG_BPW + 1;
155 case 2: if ((x = s[0] &~ m[0]) != 0)
157 else if ((x = s[1] &~ m[1]) != 0)
164 case 1: if ((x = *s &~ *m) != 0)
172 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
175 struct sigqueue *q = NULL;
176 struct user_struct *user;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user->sigpending);
185 if (override_rlimit ||
186 atomic_read(&user->sigpending) <=
187 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
188 q = kmem_cache_alloc(sigqueue_cachep, flags);
189 if (unlikely(q == NULL)) {
190 atomic_dec(&user->sigpending);
192 INIT_LIST_HEAD(&q->list);
194 q->user = get_uid(user);
199 static void __sigqueue_free(struct sigqueue *q)
201 if (q->flags & SIGQUEUE_PREALLOC)
203 atomic_dec(&q->user->sigpending);
205 kmem_cache_free(sigqueue_cachep, q);
208 void flush_sigqueue(struct sigpending *queue)
212 sigemptyset(&queue->signal);
213 while (!list_empty(&queue->list)) {
214 q = list_entry(queue->list.next, struct sigqueue , list);
215 list_del_init(&q->list);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct *t)
227 spin_lock_irqsave(&t->sighand->siglock, flags);
228 clear_tsk_thread_flag(t, TIF_SIGPENDING);
229 flush_sigqueue(&t->pending);
230 flush_sigqueue(&t->signal->shared_pending);
231 spin_unlock_irqrestore(&t->sighand->siglock, flags);
234 void ignore_signals(struct task_struct *t)
238 for (i = 0; i < _NSIG; ++i)
239 t->sighand->action[i].sa.sa_handler = SIG_IGN;
245 * Flush all handlers for a task.
249 flush_signal_handlers(struct task_struct *t, int force_default)
252 struct k_sigaction *ka = &t->sighand->action[0];
253 for (i = _NSIG ; i != 0 ; i--) {
254 if (force_default || ka->sa.sa_handler != SIG_IGN)
255 ka->sa.sa_handler = SIG_DFL;
257 sigemptyset(&ka->sa.sa_mask);
262 int unhandled_signal(struct task_struct *tsk, int sig)
264 if (is_global_init(tsk))
266 if (tsk->ptrace & PT_PTRACED)
268 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
269 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
273 /* Notify the system that a driver wants to block all signals for this
274 * process, and wants to be notified if any signals at all were to be
275 * sent/acted upon. If the notifier routine returns non-zero, then the
276 * signal will be acted upon after all. If the notifier routine returns 0,
277 * then then signal will be blocked. Only one block per process is
278 * allowed. priv is a pointer to private data that the notifier routine
279 * can use to determine if the signal should be blocked or not. */
282 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
286 spin_lock_irqsave(¤t->sighand->siglock, flags);
287 current->notifier_mask = mask;
288 current->notifier_data = priv;
289 current->notifier = notifier;
290 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
293 /* Notify the system that blocking has ended. */
296 unblock_all_signals(void)
300 spin_lock_irqsave(¤t->sighand->siglock, flags);
301 current->notifier = NULL;
302 current->notifier_data = NULL;
304 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
307 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
309 struct sigqueue *q, *first = NULL;
310 int still_pending = 0;
312 if (unlikely(!sigismember(&list->signal, sig)))
316 * Collect the siginfo appropriate to this signal. Check if
317 * there is another siginfo for the same signal.
319 list_for_each_entry(q, &list->list, list) {
320 if (q->info.si_signo == sig) {
329 list_del_init(&first->list);
330 copy_siginfo(info, &first->info);
331 __sigqueue_free(first);
333 sigdelset(&list->signal, sig);
336 /* Ok, it wasn't in the queue. This must be
337 a fast-pathed signal or we must have been
338 out of queue space. So zero out the info.
340 sigdelset(&list->signal, sig);
341 info->si_signo = sig;
350 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
353 int sig = next_signal(pending, mask);
356 if (current->notifier) {
357 if (sigismember(current->notifier_mask, sig)) {
358 if (!(current->notifier)(current->notifier_data)) {
359 clear_thread_flag(TIF_SIGPENDING);
365 if (!collect_signal(sig, pending, info))
373 * Dequeue a signal and return the element to the caller, which is
374 * expected to free it.
376 * All callers have to hold the siglock.
378 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
382 /* We only dequeue private signals from ourselves, we don't let
383 * signalfd steal them
385 signr = __dequeue_signal(&tsk->pending, mask, info);
387 signr = __dequeue_signal(&tsk->signal->shared_pending,
392 * itimers are process shared and we restart periodic
393 * itimers in the signal delivery path to prevent DoS
394 * attacks in the high resolution timer case. This is
395 * compliant with the old way of self restarting
396 * itimers, as the SIGALRM is a legacy signal and only
397 * queued once. Changing the restart behaviour to
398 * restart the timer in the signal dequeue path is
399 * reducing the timer noise on heavy loaded !highres
402 if (unlikely(signr == SIGALRM)) {
403 struct hrtimer *tmr = &tsk->signal->real_timer;
405 if (!hrtimer_is_queued(tmr) &&
406 tsk->signal->it_real_incr.tv64 != 0) {
407 hrtimer_forward(tmr, tmr->base->get_time(),
408 tsk->signal->it_real_incr);
409 hrtimer_restart(tmr);
418 if (unlikely(sig_kernel_stop(signr))) {
420 * Set a marker that we have dequeued a stop signal. Our
421 * caller might release the siglock and then the pending
422 * stop signal it is about to process is no longer in the
423 * pending bitmasks, but must still be cleared by a SIGCONT
424 * (and overruled by a SIGKILL). So those cases clear this
425 * shared flag after we've set it. Note that this flag may
426 * remain set after the signal we return is ignored or
427 * handled. That doesn't matter because its only purpose
428 * is to alert stop-signal processing code when another
429 * processor has come along and cleared the flag.
431 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
432 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
434 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
436 * Release the siglock to ensure proper locking order
437 * of timer locks outside of siglocks. Note, we leave
438 * irqs disabled here, since the posix-timers code is
439 * about to disable them again anyway.
441 spin_unlock(&tsk->sighand->siglock);
442 do_schedule_next_timer(info);
443 spin_lock(&tsk->sighand->siglock);
449 * Tell a process that it has a new active signal..
451 * NOTE! we rely on the previous spin_lock to
452 * lock interrupts for us! We can only be called with
453 * "siglock" held, and the local interrupt must
454 * have been disabled when that got acquired!
456 * No need to set need_resched since signal event passing
457 * goes through ->blocked
459 void signal_wake_up(struct task_struct *t, int resume)
463 set_tsk_thread_flag(t, TIF_SIGPENDING);
466 * For SIGKILL, we want to wake it up in the stopped/traced/killable
467 * case. We don't check t->state here because there is a race with it
468 * executing another processor and just now entering stopped state.
469 * By using wake_up_state, we ensure the process will wake up and
470 * handle its death signal.
472 mask = TASK_INTERRUPTIBLE;
474 mask |= TASK_WAKEKILL;
475 if (!wake_up_state(t, mask))
480 * Remove signals in mask from the pending set and queue.
481 * Returns 1 if any signals were found.
483 * All callers must be holding the siglock.
485 * This version takes a sigset mask and looks at all signals,
486 * not just those in the first mask word.
488 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
490 struct sigqueue *q, *n;
493 sigandsets(&m, mask, &s->signal);
494 if (sigisemptyset(&m))
497 signandsets(&s->signal, &s->signal, mask);
498 list_for_each_entry_safe(q, n, &s->list, list) {
499 if (sigismember(mask, q->info.si_signo)) {
500 list_del_init(&q->list);
507 * Remove signals in mask from the pending set and queue.
508 * Returns 1 if any signals were found.
510 * All callers must be holding the siglock.
512 static int rm_from_queue(unsigned long mask, struct sigpending *s)
514 struct sigqueue *q, *n;
516 if (!sigtestsetmask(&s->signal, mask))
519 sigdelsetmask(&s->signal, mask);
520 list_for_each_entry_safe(q, n, &s->list, list) {
521 if (q->info.si_signo < SIGRTMIN &&
522 (mask & sigmask(q->info.si_signo))) {
523 list_del_init(&q->list);
531 * Bad permissions for sending the signal
533 static int check_kill_permission(int sig, struct siginfo *info,
534 struct task_struct *t)
538 if (!valid_signal(sig))
541 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
544 error = audit_signal_info(sig, t); /* Let audit system see the signal */
548 if (((sig != SIGCONT) || (task_session_nr(current) != task_session_nr(t)))
549 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
550 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
551 && !capable(CAP_KILL))
554 return security_task_kill(t, info, sig, 0);
558 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
561 * Handle magic process-wide effects of stop/continue signals.
562 * Unlike the signal actions, these happen immediately at signal-generation
563 * time regardless of blocking, ignoring, or handling. This does the
564 * actual continuing for SIGCONT, but not the actual stopping for stop
565 * signals. The process stop is done as a signal action for SIG_DFL.
567 static void handle_stop_signal(int sig, struct task_struct *p)
569 struct signal_struct *signal = p->signal;
570 struct task_struct *t;
572 if (signal->flags & SIGNAL_GROUP_EXIT)
574 * The process is in the middle of dying already.
578 if (sig_kernel_stop(sig)) {
580 * This is a stop signal. Remove SIGCONT from all queues.
582 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
585 rm_from_queue(sigmask(SIGCONT), &t->pending);
586 } while_each_thread(p, t);
587 } else if (sig == SIGCONT) {
590 * Remove all stop signals from all queues,
591 * and wake all threads.
593 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
597 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
599 * If there is a handler for SIGCONT, we must make
600 * sure that no thread returns to user mode before
601 * we post the signal, in case it was the only
602 * thread eligible to run the signal handler--then
603 * it must not do anything between resuming and
604 * running the handler. With the TIF_SIGPENDING
605 * flag set, the thread will pause and acquire the
606 * siglock that we hold now and until we've queued
607 * the pending signal.
609 * Wake up the stopped thread _after_ setting
612 state = __TASK_STOPPED;
613 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
614 set_tsk_thread_flag(t, TIF_SIGPENDING);
615 state |= TASK_INTERRUPTIBLE;
617 wake_up_state(t, state);
618 } while_each_thread(p, t);
621 * Notify the parent with CLD_CONTINUED if we were stopped.
623 * If we were in the middle of a group stop, we pretend it
624 * was already finished, and then continued. Since SIGCHLD
625 * doesn't queue we report only CLD_STOPPED, as if the next
626 * CLD_CONTINUED was dropped.
629 if (signal->flags & SIGNAL_STOP_STOPPED)
630 why |= SIGNAL_CLD_CONTINUED;
631 else if (signal->group_stop_count)
632 why |= SIGNAL_CLD_STOPPED;
635 signal->flags = why | SIGNAL_STOP_CONTINUED;
636 signal->group_stop_count = 0;
637 signal->group_exit_code = 0;
640 * We are not stopped, but there could be a stop
641 * signal in the middle of being processed after
642 * being removed from the queue. Clear that too.
644 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
646 } else if (sig == SIGKILL) {
648 * Make sure that any pending stop signal already dequeued
649 * is undone by the wakeup for SIGKILL.
651 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
655 static inline int legacy_queue(struct sigpending *signals, int sig)
657 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
660 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
661 struct sigpending *signals)
663 struct sigqueue * q = NULL;
666 * Short-circuit ignored signals and support queuing
667 * exactly one non-rt signal, so that we can get more
668 * detailed information about the cause of the signal.
670 if (sig_ignored(t, sig) || legacy_queue(signals, sig))
674 * Deliver the signal to listening signalfds. This must be called
675 * with the sighand lock held.
677 signalfd_notify(t, sig);
680 * fast-pathed signals for kernel-internal things like SIGSTOP
683 if (info == SEND_SIG_FORCED)
686 /* Real-time signals must be queued if sent by sigqueue, or
687 some other real-time mechanism. It is implementation
688 defined whether kill() does so. We attempt to do so, on
689 the principle of least surprise, but since kill is not
690 allowed to fail with EAGAIN when low on memory we just
691 make sure at least one signal gets delivered and don't
692 pass on the info struct. */
694 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
695 (is_si_special(info) ||
696 info->si_code >= 0)));
698 list_add_tail(&q->list, &signals->list);
699 switch ((unsigned long) info) {
700 case (unsigned long) SEND_SIG_NOINFO:
701 q->info.si_signo = sig;
702 q->info.si_errno = 0;
703 q->info.si_code = SI_USER;
704 q->info.si_pid = task_pid_vnr(current);
705 q->info.si_uid = current->uid;
707 case (unsigned long) SEND_SIG_PRIV:
708 q->info.si_signo = sig;
709 q->info.si_errno = 0;
710 q->info.si_code = SI_KERNEL;
715 copy_siginfo(&q->info, info);
718 } else if (!is_si_special(info)) {
719 if (sig >= SIGRTMIN && info->si_code != SI_USER)
721 * Queue overflow, abort. We may abort if the signal was rt
722 * and sent by user using something other than kill().
728 sigaddset(&signals->signal, sig);
732 int print_fatal_signals;
734 static void print_fatal_signal(struct pt_regs *regs, int signr)
736 printk("%s/%d: potentially unexpected fatal signal %d.\n",
737 current->comm, task_pid_nr(current), signr);
739 #if defined(__i386__) && !defined(__arch_um__)
740 printk("code at %08lx: ", regs->ip);
743 for (i = 0; i < 16; i++) {
746 __get_user(insn, (unsigned char *)(regs->ip + i));
747 printk("%02x ", insn);
755 static int __init setup_print_fatal_signals(char *str)
757 get_option (&str, &print_fatal_signals);
762 __setup("print-fatal-signals=", setup_print_fatal_signals);
765 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
769 BUG_ON(!irqs_disabled());
770 assert_spin_locked(&t->sighand->siglock);
772 ret = send_signal(sig, info, t, &t->pending);
776 if (!sigismember(&t->blocked, sig))
777 signal_wake_up(t, sig == SIGKILL);
782 * Force a signal that the process can't ignore: if necessary
783 * we unblock the signal and change any SIG_IGN to SIG_DFL.
785 * Note: If we unblock the signal, we always reset it to SIG_DFL,
786 * since we do not want to have a signal handler that was blocked
787 * be invoked when user space had explicitly blocked it.
789 * We don't want to have recursive SIGSEGV's etc, for example.
792 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
794 unsigned long int flags;
795 int ret, blocked, ignored;
796 struct k_sigaction *action;
798 spin_lock_irqsave(&t->sighand->siglock, flags);
799 action = &t->sighand->action[sig-1];
800 ignored = action->sa.sa_handler == SIG_IGN;
801 blocked = sigismember(&t->blocked, sig);
802 if (blocked || ignored) {
803 action->sa.sa_handler = SIG_DFL;
805 sigdelset(&t->blocked, sig);
806 recalc_sigpending_and_wake(t);
809 ret = specific_send_sig_info(sig, info, t);
810 spin_unlock_irqrestore(&t->sighand->siglock, flags);
816 force_sig_specific(int sig, struct task_struct *t)
818 force_sig_info(sig, SEND_SIG_FORCED, t);
822 * Test if P wants to take SIG. After we've checked all threads with this,
823 * it's equivalent to finding no threads not blocking SIG. Any threads not
824 * blocking SIG were ruled out because they are not running and already
825 * have pending signals. Such threads will dequeue from the shared queue
826 * as soon as they're available, so putting the signal on the shared queue
827 * will be equivalent to sending it to one such thread.
829 static inline int wants_signal(int sig, struct task_struct *p)
831 if (sigismember(&p->blocked, sig))
833 if (p->flags & PF_EXITING)
837 if (task_is_stopped_or_traced(p))
839 return task_curr(p) || !signal_pending(p);
843 __group_complete_signal(int sig, struct task_struct *p)
845 struct task_struct *t;
848 * Now find a thread we can wake up to take the signal off the queue.
850 * If the main thread wants the signal, it gets first crack.
851 * Probably the least surprising to the average bear.
853 if (wants_signal(sig, p))
855 else if (thread_group_empty(p))
857 * There is just one thread and it does not need to be woken.
858 * It will dequeue unblocked signals before it runs again.
863 * Otherwise try to find a suitable thread.
865 t = p->signal->curr_target;
867 /* restart balancing at this thread */
868 t = p->signal->curr_target = p;
870 while (!wants_signal(sig, t)) {
872 if (t == p->signal->curr_target)
874 * No thread needs to be woken.
875 * Any eligible threads will see
876 * the signal in the queue soon.
880 p->signal->curr_target = t;
884 * Found a killable thread. If the signal will be fatal,
885 * then start taking the whole group down immediately.
887 if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
888 !sigismember(&t->real_blocked, sig) &&
889 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
891 * This signal will be fatal to the whole group.
893 if (!sig_kernel_coredump(sig)) {
895 * Start a group exit and wake everybody up.
896 * This way we don't have other threads
897 * running and doing things after a slower
898 * thread has the fatal signal pending.
900 p->signal->flags = SIGNAL_GROUP_EXIT;
901 p->signal->group_exit_code = sig;
902 p->signal->group_stop_count = 0;
905 sigaddset(&t->pending.signal, SIGKILL);
906 signal_wake_up(t, 1);
907 } while_each_thread(p, t);
913 * The signal is already in the shared-pending queue.
914 * Tell the chosen thread to wake up and dequeue it.
916 signal_wake_up(t, sig == SIGKILL);
921 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
925 assert_spin_locked(&p->sighand->siglock);
926 handle_stop_signal(sig, p);
929 * Put this signal on the shared-pending queue, or fail with EAGAIN.
930 * We always use the shared queue for process-wide signals,
931 * to avoid several races.
933 ret = send_signal(sig, info, p, &p->signal->shared_pending);
937 __group_complete_signal(sig, p);
942 * Nuke all other threads in the group.
944 void zap_other_threads(struct task_struct *p)
946 struct task_struct *t;
948 p->signal->group_stop_count = 0;
950 for (t = next_thread(p); t != p; t = next_thread(t)) {
952 * Don't bother with already dead threads
957 /* SIGKILL will be handled before any pending SIGSTOP */
958 sigaddset(&t->pending.signal, SIGKILL);
959 signal_wake_up(t, 1);
963 int __fatal_signal_pending(struct task_struct *tsk)
965 return sigismember(&tsk->pending.signal, SIGKILL);
967 EXPORT_SYMBOL(__fatal_signal_pending);
969 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
971 struct sighand_struct *sighand;
975 sighand = rcu_dereference(tsk->sighand);
976 if (unlikely(sighand == NULL))
979 spin_lock_irqsave(&sighand->siglock, *flags);
980 if (likely(sighand == tsk->sighand))
982 spin_unlock_irqrestore(&sighand->siglock, *flags);
989 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
994 ret = check_kill_permission(sig, info, p);
998 if (lock_task_sighand(p, &flags)) {
999 ret = __group_send_sig_info(sig, info, p);
1000 unlock_task_sighand(p, &flags);
1008 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1009 * control characters do (^C, ^Z etc)
1012 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1014 struct task_struct *p = NULL;
1015 int retval, success;
1019 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1020 int err = group_send_sig_info(sig, info, p);
1023 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1024 return success ? 0 : retval;
1027 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1030 struct task_struct *p;
1034 p = pid_task(pid, PIDTYPE_PID);
1036 error = group_send_sig_info(sig, info, p);
1037 if (unlikely(error == -ESRCH))
1039 * The task was unhashed in between, try again.
1040 * If it is dead, pid_task() will return NULL,
1041 * if we race with de_thread() it will find the
1052 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1056 error = kill_pid_info(sig, info, find_vpid(pid));
1061 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1062 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1063 uid_t uid, uid_t euid, u32 secid)
1066 struct task_struct *p;
1068 if (!valid_signal(sig))
1071 read_lock(&tasklist_lock);
1072 p = pid_task(pid, PIDTYPE_PID);
1077 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1078 && (euid != p->suid) && (euid != p->uid)
1079 && (uid != p->suid) && (uid != p->uid)) {
1083 ret = security_task_kill(p, info, sig, secid);
1086 if (sig && p->sighand) {
1087 unsigned long flags;
1088 spin_lock_irqsave(&p->sighand->siglock, flags);
1089 ret = __group_send_sig_info(sig, info, p);
1090 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1093 read_unlock(&tasklist_lock);
1096 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1099 * kill_something_info() interprets pid in interesting ways just like kill(2).
1101 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1102 * is probably wrong. Should make it like BSD or SYSV.
1105 static int kill_something_info(int sig, struct siginfo *info, int pid)
1111 ret = kill_pid_info(sig, info, find_vpid(pid));
1116 read_lock(&tasklist_lock);
1118 ret = __kill_pgrp_info(sig, info,
1119 pid ? find_vpid(-pid) : task_pgrp(current));
1121 int retval = 0, count = 0;
1122 struct task_struct * p;
1124 for_each_process(p) {
1125 if (p->pid > 1 && !same_thread_group(p, current)) {
1126 int err = group_send_sig_info(sig, info, p);
1132 ret = count ? retval : -ESRCH;
1134 read_unlock(&tasklist_lock);
1140 * These are for backward compatibility with the rest of the kernel source.
1144 * These two are the most common entry points. They send a signal
1145 * just to the specific thread.
1148 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1151 unsigned long flags;
1154 * Make sure legacy kernel users don't send in bad values
1155 * (normal paths check this in check_kill_permission).
1157 if (!valid_signal(sig))
1161 * We need the tasklist lock even for the specific
1162 * thread case (when we don't need to follow the group
1163 * lists) in order to avoid races with "p->sighand"
1164 * going away or changing from under us.
1166 read_lock(&tasklist_lock);
1167 spin_lock_irqsave(&p->sighand->siglock, flags);
1168 ret = specific_send_sig_info(sig, info, p);
1169 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1170 read_unlock(&tasklist_lock);
1174 #define __si_special(priv) \
1175 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1178 send_sig(int sig, struct task_struct *p, int priv)
1180 return send_sig_info(sig, __si_special(priv), p);
1184 force_sig(int sig, struct task_struct *p)
1186 force_sig_info(sig, SEND_SIG_PRIV, p);
1190 * When things go south during signal handling, we
1191 * will force a SIGSEGV. And if the signal that caused
1192 * the problem was already a SIGSEGV, we'll want to
1193 * make sure we don't even try to deliver the signal..
1196 force_sigsegv(int sig, struct task_struct *p)
1198 if (sig == SIGSEGV) {
1199 unsigned long flags;
1200 spin_lock_irqsave(&p->sighand->siglock, flags);
1201 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1202 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1204 force_sig(SIGSEGV, p);
1208 int kill_pgrp(struct pid *pid, int sig, int priv)
1212 read_lock(&tasklist_lock);
1213 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1214 read_unlock(&tasklist_lock);
1218 EXPORT_SYMBOL(kill_pgrp);
1220 int kill_pid(struct pid *pid, int sig, int priv)
1222 return kill_pid_info(sig, __si_special(priv), pid);
1224 EXPORT_SYMBOL(kill_pid);
1227 kill_proc(pid_t pid, int sig, int priv)
1232 ret = kill_pid_info(sig, __si_special(priv), find_pid(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 * If the signal is still pending remove it from the
1264 * pending queue. We must hold ->siglock while testing
1265 * q->list to serialize with collect_signal().
1267 spin_lock_irqsave(lock, flags);
1268 if (!list_empty(&q->list))
1269 list_del_init(&q->list);
1270 spin_unlock_irqrestore(lock, flags);
1272 q->flags &= ~SIGQUEUE_PREALLOC;
1276 static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
1277 struct sigpending *pending)
1279 handle_stop_signal(sig, t);
1281 if (unlikely(!list_empty(&q->list))) {
1283 * If an SI_TIMER entry is already queue just increment
1284 * the overrun count.
1287 BUG_ON(q->info.si_code != SI_TIMER);
1288 q->info.si_overrun++;
1292 if (sig_ignored(t, sig))
1295 signalfd_notify(t, sig);
1296 list_add_tail(&q->list, &pending->list);
1297 sigaddset(&pending->signal, sig);
1301 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1303 unsigned long flags;
1306 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1309 * The rcu based delayed sighand destroy makes it possible to
1310 * run this without tasklist lock held. The task struct itself
1311 * cannot go away as create_timer did get_task_struct().
1313 * We return -1, when the task is marked exiting, so
1314 * posix_timer_event can redirect it to the group leader
1316 if (!likely(lock_task_sighand(p, &flags)))
1319 ret = do_send_sigqueue(sig, q, p, &p->pending);
1321 if (!sigismember(&p->blocked, sig))
1322 signal_wake_up(p, sig == SIGKILL);
1324 unlock_task_sighand(p, &flags);
1330 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1332 unsigned long flags;
1335 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1337 read_lock(&tasklist_lock);
1338 /* Since it_lock is held, p->sighand cannot be NULL. */
1339 spin_lock_irqsave(&p->sighand->siglock, flags);
1341 ret = do_send_sigqueue(sig, q, p, &p->signal->shared_pending);
1343 __group_complete_signal(sig, p);
1345 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1346 read_unlock(&tasklist_lock);
1351 * Wake up any threads in the parent blocked in wait* syscalls.
1353 static inline void __wake_up_parent(struct task_struct *p,
1354 struct task_struct *parent)
1356 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1360 * Let a parent know about the death of a child.
1361 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1364 void do_notify_parent(struct task_struct *tsk, int sig)
1366 struct siginfo info;
1367 unsigned long flags;
1368 struct sighand_struct *psig;
1372 /* do_notify_parent_cldstop should have been called instead. */
1373 BUG_ON(task_is_stopped_or_traced(tsk));
1375 BUG_ON(!tsk->ptrace &&
1376 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1378 info.si_signo = sig;
1381 * we are under tasklist_lock here so our parent is tied to
1382 * us and cannot exit and release its namespace.
1384 * the only it can is to switch its nsproxy with sys_unshare,
1385 * bu uncharing pid namespaces is not allowed, so we'll always
1386 * see relevant namespace
1388 * write_lock() currently calls preempt_disable() which is the
1389 * same as rcu_read_lock(), but according to Oleg, this is not
1390 * correct to rely on this
1393 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1396 info.si_uid = tsk->uid;
1398 /* FIXME: find out whether or not this is supposed to be c*time. */
1399 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1400 tsk->signal->utime));
1401 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1402 tsk->signal->stime));
1404 info.si_status = tsk->exit_code & 0x7f;
1405 if (tsk->exit_code & 0x80)
1406 info.si_code = CLD_DUMPED;
1407 else if (tsk->exit_code & 0x7f)
1408 info.si_code = CLD_KILLED;
1410 info.si_code = CLD_EXITED;
1411 info.si_status = tsk->exit_code >> 8;
1414 psig = tsk->parent->sighand;
1415 spin_lock_irqsave(&psig->siglock, flags);
1416 if (!tsk->ptrace && sig == SIGCHLD &&
1417 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1418 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1420 * We are exiting and our parent doesn't care. POSIX.1
1421 * defines special semantics for setting SIGCHLD to SIG_IGN
1422 * or setting the SA_NOCLDWAIT flag: we should be reaped
1423 * automatically and not left for our parent's wait4 call.
1424 * Rather than having the parent do it as a magic kind of
1425 * signal handler, we just set this to tell do_exit that we
1426 * can be cleaned up without becoming a zombie. Note that
1427 * we still call __wake_up_parent in this case, because a
1428 * blocked sys_wait4 might now return -ECHILD.
1430 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1431 * is implementation-defined: we do (if you don't want
1432 * it, just use SIG_IGN instead).
1434 tsk->exit_signal = -1;
1435 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1438 if (valid_signal(sig) && sig > 0)
1439 __group_send_sig_info(sig, &info, tsk->parent);
1440 __wake_up_parent(tsk, tsk->parent);
1441 spin_unlock_irqrestore(&psig->siglock, flags);
1444 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1446 struct siginfo info;
1447 unsigned long flags;
1448 struct task_struct *parent;
1449 struct sighand_struct *sighand;
1451 if (tsk->ptrace & PT_PTRACED)
1452 parent = tsk->parent;
1454 tsk = tsk->group_leader;
1455 parent = tsk->real_parent;
1458 info.si_signo = SIGCHLD;
1461 * see comment in do_notify_parent() abot the following 3 lines
1464 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1467 info.si_uid = tsk->uid;
1469 /* FIXME: find out whether or not this is supposed to be c*time. */
1470 info.si_utime = cputime_to_jiffies(tsk->utime);
1471 info.si_stime = cputime_to_jiffies(tsk->stime);
1476 info.si_status = SIGCONT;
1479 info.si_status = tsk->signal->group_exit_code & 0x7f;
1482 info.si_status = tsk->exit_code & 0x7f;
1488 sighand = parent->sighand;
1489 spin_lock_irqsave(&sighand->siglock, flags);
1490 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1491 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1492 __group_send_sig_info(SIGCHLD, &info, parent);
1494 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1496 __wake_up_parent(tsk, parent);
1497 spin_unlock_irqrestore(&sighand->siglock, flags);
1500 static inline int may_ptrace_stop(void)
1502 if (!likely(current->ptrace & PT_PTRACED))
1505 * Are we in the middle of do_coredump?
1506 * If so and our tracer is also part of the coredump stopping
1507 * is a deadlock situation, and pointless because our tracer
1508 * is dead so don't allow us to stop.
1509 * If SIGKILL was already sent before the caller unlocked
1510 * ->siglock we must see ->core_waiters != 0. Otherwise it
1511 * is safe to enter schedule().
1513 if (unlikely(current->mm->core_waiters) &&
1514 unlikely(current->mm == current->parent->mm))
1521 * Return nonzero if there is a SIGKILL that should be waking us up.
1522 * Called with the siglock held.
1524 static int sigkill_pending(struct task_struct *tsk)
1526 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1527 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1528 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1532 * This must be called with current->sighand->siglock held.
1534 * This should be the path for all ptrace stops.
1535 * We always set current->last_siginfo while stopped here.
1536 * That makes it a way to test a stopped process for
1537 * being ptrace-stopped vs being job-control-stopped.
1539 * If we actually decide not to stop at all because the tracer
1540 * is gone, we keep current->exit_code unless clear_code.
1542 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1546 if (arch_ptrace_stop_needed(exit_code, info)) {
1548 * The arch code has something special to do before a
1549 * ptrace stop. This is allowed to block, e.g. for faults
1550 * on user stack pages. We can't keep the siglock while
1551 * calling arch_ptrace_stop, so we must release it now.
1552 * To preserve proper semantics, we must do this before
1553 * any signal bookkeeping like checking group_stop_count.
1554 * Meanwhile, a SIGKILL could come in before we retake the
1555 * siglock. That must prevent us from sleeping in TASK_TRACED.
1556 * So after regaining the lock, we must check for SIGKILL.
1558 spin_unlock_irq(¤t->sighand->siglock);
1559 arch_ptrace_stop(exit_code, info);
1560 spin_lock_irq(¤t->sighand->siglock);
1561 killed = sigkill_pending(current);
1565 * If there is a group stop in progress,
1566 * we must participate in the bookkeeping.
1568 if (current->signal->group_stop_count > 0)
1569 --current->signal->group_stop_count;
1571 current->last_siginfo = info;
1572 current->exit_code = exit_code;
1574 /* Let the debugger run. */
1575 __set_current_state(TASK_TRACED);
1576 spin_unlock_irq(¤t->sighand->siglock);
1577 read_lock(&tasklist_lock);
1578 if (!unlikely(killed) && may_ptrace_stop()) {
1579 do_notify_parent_cldstop(current, CLD_TRAPPED);
1580 read_unlock(&tasklist_lock);
1584 * By the time we got the lock, our tracer went away.
1585 * Don't drop the lock yet, another tracer may come.
1587 __set_current_state(TASK_RUNNING);
1589 current->exit_code = 0;
1590 read_unlock(&tasklist_lock);
1594 * While in TASK_TRACED, we were considered "frozen enough".
1595 * Now that we woke up, it's crucial if we're supposed to be
1596 * frozen that we freeze now before running anything substantial.
1601 * We are back. Now reacquire the siglock before touching
1602 * last_siginfo, so that we are sure to have synchronized with
1603 * any signal-sending on another CPU that wants to examine it.
1605 spin_lock_irq(¤t->sighand->siglock);
1606 current->last_siginfo = NULL;
1609 * Queued signals ignored us while we were stopped for tracing.
1610 * So check for any that we should take before resuming user mode.
1611 * This sets TIF_SIGPENDING, but never clears it.
1613 recalc_sigpending_tsk(current);
1616 void ptrace_notify(int exit_code)
1620 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1622 memset(&info, 0, sizeof info);
1623 info.si_signo = SIGTRAP;
1624 info.si_code = exit_code;
1625 info.si_pid = task_pid_vnr(current);
1626 info.si_uid = current->uid;
1628 /* Let the debugger run. */
1629 spin_lock_irq(¤t->sighand->siglock);
1630 ptrace_stop(exit_code, 1, &info);
1631 spin_unlock_irq(¤t->sighand->siglock);
1635 finish_stop(int stop_count)
1638 * If there are no other threads in the group, or if there is
1639 * a group stop in progress and we are the last to stop,
1640 * report to the parent. When ptraced, every thread reports itself.
1642 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1643 read_lock(&tasklist_lock);
1644 do_notify_parent_cldstop(current, CLD_STOPPED);
1645 read_unlock(&tasklist_lock);
1650 } while (try_to_freeze());
1652 * Now we don't run again until continued.
1654 current->exit_code = 0;
1658 * This performs the stopping for SIGSTOP and other stop signals.
1659 * We have to stop all threads in the thread group.
1660 * Returns nonzero if we've actually stopped and released the siglock.
1661 * Returns zero if we didn't stop and still hold the siglock.
1663 static int do_signal_stop(int signr)
1665 struct signal_struct *sig = current->signal;
1668 if (sig->group_stop_count > 0) {
1670 * There is a group stop in progress. We don't need to
1671 * start another one.
1673 stop_count = --sig->group_stop_count;
1675 struct task_struct *t;
1677 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1678 unlikely(signal_group_exit(sig)))
1681 * There is no group stop already in progress.
1682 * We must initiate one now.
1684 sig->group_exit_code = signr;
1687 for (t = next_thread(current); t != current; t = next_thread(t))
1689 * Setting state to TASK_STOPPED for a group
1690 * stop is always done with the siglock held,
1691 * so this check has no races.
1693 if (!(t->flags & PF_EXITING) &&
1694 !task_is_stopped_or_traced(t)) {
1696 signal_wake_up(t, 0);
1698 sig->group_stop_count = stop_count;
1701 if (stop_count == 0)
1702 sig->flags = SIGNAL_STOP_STOPPED;
1703 current->exit_code = sig->group_exit_code;
1704 __set_current_state(TASK_STOPPED);
1706 spin_unlock_irq(¤t->sighand->siglock);
1707 finish_stop(stop_count);
1711 static int ptrace_signal(int signr, siginfo_t *info,
1712 struct pt_regs *regs, void *cookie)
1714 if (!(current->ptrace & PT_PTRACED))
1717 ptrace_signal_deliver(regs, cookie);
1719 /* Let the debugger run. */
1720 ptrace_stop(signr, 0, info);
1722 /* We're back. Did the debugger cancel the sig? */
1723 signr = current->exit_code;
1727 current->exit_code = 0;
1729 /* Update the siginfo structure if the signal has
1730 changed. If the debugger wanted something
1731 specific in the siginfo structure then it should
1732 have updated *info via PTRACE_SETSIGINFO. */
1733 if (signr != info->si_signo) {
1734 info->si_signo = signr;
1736 info->si_code = SI_USER;
1737 info->si_pid = task_pid_vnr(current->parent);
1738 info->si_uid = current->parent->uid;
1741 /* If the (new) signal is now blocked, requeue it. */
1742 if (sigismember(¤t->blocked, signr)) {
1743 specific_send_sig_info(signr, info, current);
1750 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1751 struct pt_regs *regs, void *cookie)
1753 struct sighand_struct *sighand = current->sighand;
1754 struct signal_struct *signal = current->signal;
1759 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1760 * While in TASK_STOPPED, we were considered "frozen enough".
1761 * Now that we woke up, it's crucial if we're supposed to be
1762 * frozen that we freeze now before running anything substantial.
1766 spin_lock_irq(&sighand->siglock);
1768 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1769 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1770 ? CLD_CONTINUED : CLD_STOPPED;
1771 signal->flags &= ~SIGNAL_CLD_MASK;
1772 spin_unlock_irq(&sighand->siglock);
1774 read_lock(&tasklist_lock);
1775 do_notify_parent_cldstop(current->group_leader, why);
1776 read_unlock(&tasklist_lock);
1781 struct k_sigaction *ka;
1783 if (unlikely(signal->group_stop_count > 0) &&
1787 signr = dequeue_signal(current, ¤t->blocked, info);
1789 break; /* will return 0 */
1791 if (signr != SIGKILL) {
1792 signr = ptrace_signal(signr, info, regs, cookie);
1797 ka = &sighand->action[signr-1];
1798 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1800 if (ka->sa.sa_handler != SIG_DFL) {
1801 /* Run the handler. */
1804 if (ka->sa.sa_flags & SA_ONESHOT)
1805 ka->sa.sa_handler = SIG_DFL;
1807 break; /* will return non-zero "signr" value */
1811 * Now we are doing the default action for this signal.
1813 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1817 * Global init gets no signals it doesn't want.
1819 if (is_global_init(current))
1822 if (sig_kernel_stop(signr)) {
1824 * The default action is to stop all threads in
1825 * the thread group. The job control signals
1826 * do nothing in an orphaned pgrp, but SIGSTOP
1827 * always works. Note that siglock needs to be
1828 * dropped during the call to is_orphaned_pgrp()
1829 * because of lock ordering with tasklist_lock.
1830 * This allows an intervening SIGCONT to be posted.
1831 * We need to check for that and bail out if necessary.
1833 if (signr != SIGSTOP) {
1834 spin_unlock_irq(&sighand->siglock);
1836 /* signals can be posted during this window */
1838 if (is_current_pgrp_orphaned())
1841 spin_lock_irq(&sighand->siglock);
1844 if (likely(do_signal_stop(signr))) {
1845 /* It released the siglock. */
1850 * We didn't actually stop, due to a race
1851 * with SIGCONT or something like that.
1856 spin_unlock_irq(&sighand->siglock);
1859 * Anything else is fatal, maybe with a core dump.
1861 current->flags |= PF_SIGNALED;
1862 if ((signr != SIGKILL) && print_fatal_signals)
1863 print_fatal_signal(regs, signr);
1864 if (sig_kernel_coredump(signr)) {
1866 * If it was able to dump core, this kills all
1867 * other threads in the group and synchronizes with
1868 * their demise. If we lost the race with another
1869 * thread getting here, it set group_exit_code
1870 * first and our do_group_exit call below will use
1871 * that value and ignore the one we pass it.
1873 do_coredump((long)signr, signr, regs);
1877 * Death signals, no core dump.
1879 do_group_exit(signr);
1882 spin_unlock_irq(&sighand->siglock);
1886 void exit_signals(struct task_struct *tsk)
1889 struct task_struct *t;
1891 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1892 tsk->flags |= PF_EXITING;
1896 spin_lock_irq(&tsk->sighand->siglock);
1898 * From now this task is not visible for group-wide signals,
1899 * see wants_signal(), do_signal_stop().
1901 tsk->flags |= PF_EXITING;
1902 if (!signal_pending(tsk))
1905 /* It could be that __group_complete_signal() choose us to
1906 * notify about group-wide signal. Another thread should be
1907 * woken now to take the signal since we will not.
1909 for (t = tsk; (t = next_thread(t)) != tsk; )
1910 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1911 recalc_sigpending_and_wake(t);
1913 if (unlikely(tsk->signal->group_stop_count) &&
1914 !--tsk->signal->group_stop_count) {
1915 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1919 spin_unlock_irq(&tsk->sighand->siglock);
1921 if (unlikely(group_stop)) {
1922 read_lock(&tasklist_lock);
1923 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1924 read_unlock(&tasklist_lock);
1928 EXPORT_SYMBOL(recalc_sigpending);
1929 EXPORT_SYMBOL_GPL(dequeue_signal);
1930 EXPORT_SYMBOL(flush_signals);
1931 EXPORT_SYMBOL(force_sig);
1932 EXPORT_SYMBOL(kill_proc);
1933 EXPORT_SYMBOL(ptrace_notify);
1934 EXPORT_SYMBOL(send_sig);
1935 EXPORT_SYMBOL(send_sig_info);
1936 EXPORT_SYMBOL(sigprocmask);
1937 EXPORT_SYMBOL(block_all_signals);
1938 EXPORT_SYMBOL(unblock_all_signals);
1942 * System call entry points.
1945 asmlinkage long sys_restart_syscall(void)
1947 struct restart_block *restart = ¤t_thread_info()->restart_block;
1948 return restart->fn(restart);
1951 long do_no_restart_syscall(struct restart_block *param)
1957 * We don't need to get the kernel lock - this is all local to this
1958 * particular thread.. (and that's good, because this is _heavily_
1959 * used by various programs)
1963 * This is also useful for kernel threads that want to temporarily
1964 * (or permanently) block certain signals.
1966 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1967 * interface happily blocks "unblockable" signals like SIGKILL
1970 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1974 spin_lock_irq(¤t->sighand->siglock);
1976 *oldset = current->blocked;
1981 sigorsets(¤t->blocked, ¤t->blocked, set);
1984 signandsets(¤t->blocked, ¤t->blocked, set);
1987 current->blocked = *set;
1992 recalc_sigpending();
1993 spin_unlock_irq(¤t->sighand->siglock);
1999 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2001 int error = -EINVAL;
2002 sigset_t old_set, new_set;
2004 /* XXX: Don't preclude handling different sized sigset_t's. */
2005 if (sigsetsize != sizeof(sigset_t))
2010 if (copy_from_user(&new_set, set, sizeof(*set)))
2012 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2014 error = sigprocmask(how, &new_set, &old_set);
2020 spin_lock_irq(¤t->sighand->siglock);
2021 old_set = current->blocked;
2022 spin_unlock_irq(¤t->sighand->siglock);
2026 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2034 long do_sigpending(void __user *set, unsigned long sigsetsize)
2036 long error = -EINVAL;
2039 if (sigsetsize > sizeof(sigset_t))
2042 spin_lock_irq(¤t->sighand->siglock);
2043 sigorsets(&pending, ¤t->pending.signal,
2044 ¤t->signal->shared_pending.signal);
2045 spin_unlock_irq(¤t->sighand->siglock);
2047 /* Outside the lock because only this thread touches it. */
2048 sigandsets(&pending, ¤t->blocked, &pending);
2051 if (!copy_to_user(set, &pending, sigsetsize))
2059 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2061 return do_sigpending(set, sigsetsize);
2064 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2066 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2070 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2072 if (from->si_code < 0)
2073 return __copy_to_user(to, from, sizeof(siginfo_t))
2076 * If you change siginfo_t structure, please be sure
2077 * this code is fixed accordingly.
2078 * Please remember to update the signalfd_copyinfo() function
2079 * inside fs/signalfd.c too, in case siginfo_t changes.
2080 * It should never copy any pad contained in the structure
2081 * to avoid security leaks, but must copy the generic
2082 * 3 ints plus the relevant union member.
2084 err = __put_user(from->si_signo, &to->si_signo);
2085 err |= __put_user(from->si_errno, &to->si_errno);
2086 err |= __put_user((short)from->si_code, &to->si_code);
2087 switch (from->si_code & __SI_MASK) {
2089 err |= __put_user(from->si_pid, &to->si_pid);
2090 err |= __put_user(from->si_uid, &to->si_uid);
2093 err |= __put_user(from->si_tid, &to->si_tid);
2094 err |= __put_user(from->si_overrun, &to->si_overrun);
2095 err |= __put_user(from->si_ptr, &to->si_ptr);
2098 err |= __put_user(from->si_band, &to->si_band);
2099 err |= __put_user(from->si_fd, &to->si_fd);
2102 err |= __put_user(from->si_addr, &to->si_addr);
2103 #ifdef __ARCH_SI_TRAPNO
2104 err |= __put_user(from->si_trapno, &to->si_trapno);
2108 err |= __put_user(from->si_pid, &to->si_pid);
2109 err |= __put_user(from->si_uid, &to->si_uid);
2110 err |= __put_user(from->si_status, &to->si_status);
2111 err |= __put_user(from->si_utime, &to->si_utime);
2112 err |= __put_user(from->si_stime, &to->si_stime);
2114 case __SI_RT: /* This is not generated by the kernel as of now. */
2115 case __SI_MESGQ: /* But this is */
2116 err |= __put_user(from->si_pid, &to->si_pid);
2117 err |= __put_user(from->si_uid, &to->si_uid);
2118 err |= __put_user(from->si_ptr, &to->si_ptr);
2120 default: /* this is just in case for now ... */
2121 err |= __put_user(from->si_pid, &to->si_pid);
2122 err |= __put_user(from->si_uid, &to->si_uid);
2131 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2132 siginfo_t __user *uinfo,
2133 const struct timespec __user *uts,
2142 /* XXX: Don't preclude handling different sized sigset_t's. */
2143 if (sigsetsize != sizeof(sigset_t))
2146 if (copy_from_user(&these, uthese, sizeof(these)))
2150 * Invert the set of allowed signals to get those we
2153 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2157 if (copy_from_user(&ts, uts, sizeof(ts)))
2159 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2164 spin_lock_irq(¤t->sighand->siglock);
2165 sig = dequeue_signal(current, &these, &info);
2167 timeout = MAX_SCHEDULE_TIMEOUT;
2169 timeout = (timespec_to_jiffies(&ts)
2170 + (ts.tv_sec || ts.tv_nsec));
2173 /* None ready -- temporarily unblock those we're
2174 * interested while we are sleeping in so that we'll
2175 * be awakened when they arrive. */
2176 current->real_blocked = current->blocked;
2177 sigandsets(¤t->blocked, ¤t->blocked, &these);
2178 recalc_sigpending();
2179 spin_unlock_irq(¤t->sighand->siglock);
2181 timeout = schedule_timeout_interruptible(timeout);
2183 spin_lock_irq(¤t->sighand->siglock);
2184 sig = dequeue_signal(current, &these, &info);
2185 current->blocked = current->real_blocked;
2186 siginitset(¤t->real_blocked, 0);
2187 recalc_sigpending();
2190 spin_unlock_irq(¤t->sighand->siglock);
2195 if (copy_siginfo_to_user(uinfo, &info))
2208 sys_kill(int pid, int sig)
2210 struct siginfo info;
2212 info.si_signo = sig;
2214 info.si_code = SI_USER;
2215 info.si_pid = task_tgid_vnr(current);
2216 info.si_uid = current->uid;
2218 return kill_something_info(sig, &info, pid);
2221 static int do_tkill(int tgid, int pid, int sig)
2224 struct siginfo info;
2225 struct task_struct *p;
2228 info.si_signo = sig;
2230 info.si_code = SI_TKILL;
2231 info.si_pid = task_tgid_vnr(current);
2232 info.si_uid = current->uid;
2234 read_lock(&tasklist_lock);
2235 p = find_task_by_vpid(pid);
2236 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2237 error = check_kill_permission(sig, &info, p);
2239 * The null signal is a permissions and process existence
2240 * probe. No signal is actually delivered.
2242 if (!error && sig && p->sighand) {
2243 spin_lock_irq(&p->sighand->siglock);
2244 handle_stop_signal(sig, p);
2245 error = specific_send_sig_info(sig, &info, p);
2246 spin_unlock_irq(&p->sighand->siglock);
2249 read_unlock(&tasklist_lock);
2255 * sys_tgkill - send signal to one specific thread
2256 * @tgid: the thread group ID of the thread
2257 * @pid: the PID of the thread
2258 * @sig: signal to be sent
2260 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2261 * exists but it's not belonging to the target process anymore. This
2262 * method solves the problem of threads exiting and PIDs getting reused.
2264 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2266 /* This is only valid for single tasks */
2267 if (pid <= 0 || tgid <= 0)
2270 return do_tkill(tgid, pid, sig);
2274 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2277 sys_tkill(int pid, int sig)
2279 /* This is only valid for single tasks */
2283 return do_tkill(0, pid, sig);
2287 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2291 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2294 /* Not even root can pretend to send signals from the kernel.
2295 Nor can they impersonate a kill(), which adds source info. */
2296 if (info.si_code >= 0)
2298 info.si_signo = sig;
2300 /* POSIX.1b doesn't mention process groups. */
2301 return kill_proc_info(sig, &info, pid);
2304 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2306 struct task_struct *t = current;
2307 struct k_sigaction *k;
2310 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2313 k = &t->sighand->action[sig-1];
2315 spin_lock_irq(¤t->sighand->siglock);
2320 sigdelsetmask(&act->sa.sa_mask,
2321 sigmask(SIGKILL) | sigmask(SIGSTOP));
2325 * "Setting a signal action to SIG_IGN for a signal that is
2326 * pending shall cause the pending signal to be discarded,
2327 * whether or not it is blocked."
2329 * "Setting a signal action to SIG_DFL for a signal that is
2330 * pending and whose default action is to ignore the signal
2331 * (for example, SIGCHLD), shall cause the pending signal to
2332 * be discarded, whether or not it is blocked"
2334 if (__sig_ignored(t, sig)) {
2336 sigaddset(&mask, sig);
2337 rm_from_queue_full(&mask, &t->signal->shared_pending);
2339 rm_from_queue_full(&mask, &t->pending);
2341 } while (t != current);
2345 spin_unlock_irq(¤t->sighand->siglock);
2350 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2356 oss.ss_sp = (void __user *) current->sas_ss_sp;
2357 oss.ss_size = current->sas_ss_size;
2358 oss.ss_flags = sas_ss_flags(sp);
2367 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2368 || __get_user(ss_sp, &uss->ss_sp)
2369 || __get_user(ss_flags, &uss->ss_flags)
2370 || __get_user(ss_size, &uss->ss_size))
2374 if (on_sig_stack(sp))
2380 * Note - this code used to test ss_flags incorrectly
2381 * old code may have been written using ss_flags==0
2382 * to mean ss_flags==SS_ONSTACK (as this was the only
2383 * way that worked) - this fix preserves that older
2386 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2389 if (ss_flags == SS_DISABLE) {
2394 if (ss_size < MINSIGSTKSZ)
2398 current->sas_ss_sp = (unsigned long) ss_sp;
2399 current->sas_ss_size = ss_size;
2404 if (copy_to_user(uoss, &oss, sizeof(oss)))
2413 #ifdef __ARCH_WANT_SYS_SIGPENDING
2416 sys_sigpending(old_sigset_t __user *set)
2418 return do_sigpending(set, sizeof(*set));
2423 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2424 /* Some platforms have their own version with special arguments others
2425 support only sys_rt_sigprocmask. */
2428 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2431 old_sigset_t old_set, new_set;
2435 if (copy_from_user(&new_set, set, sizeof(*set)))
2437 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2439 spin_lock_irq(¤t->sighand->siglock);
2440 old_set = current->blocked.sig[0];
2448 sigaddsetmask(¤t->blocked, new_set);
2451 sigdelsetmask(¤t->blocked, new_set);
2454 current->blocked.sig[0] = new_set;
2458 recalc_sigpending();
2459 spin_unlock_irq(¤t->sighand->siglock);
2465 old_set = current->blocked.sig[0];
2468 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2475 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2477 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2479 sys_rt_sigaction(int sig,
2480 const struct sigaction __user *act,
2481 struct sigaction __user *oact,
2484 struct k_sigaction new_sa, old_sa;
2487 /* XXX: Don't preclude handling different sized sigset_t's. */
2488 if (sigsetsize != sizeof(sigset_t))
2492 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2496 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2499 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2505 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2507 #ifdef __ARCH_WANT_SYS_SGETMASK
2510 * For backwards compatibility. Functionality superseded by sigprocmask.
2516 return current->blocked.sig[0];
2520 sys_ssetmask(int newmask)
2524 spin_lock_irq(¤t->sighand->siglock);
2525 old = current->blocked.sig[0];
2527 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2529 recalc_sigpending();
2530 spin_unlock_irq(¤t->sighand->siglock);
2534 #endif /* __ARCH_WANT_SGETMASK */
2536 #ifdef __ARCH_WANT_SYS_SIGNAL
2538 * For backwards compatibility. Functionality superseded by sigaction.
2540 asmlinkage unsigned long
2541 sys_signal(int sig, __sighandler_t handler)
2543 struct k_sigaction new_sa, old_sa;
2546 new_sa.sa.sa_handler = handler;
2547 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2548 sigemptyset(&new_sa.sa.sa_mask);
2550 ret = do_sigaction(sig, &new_sa, &old_sa);
2552 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2554 #endif /* __ARCH_WANT_SYS_SIGNAL */
2556 #ifdef __ARCH_WANT_SYS_PAUSE
2561 current->state = TASK_INTERRUPTIBLE;
2563 return -ERESTARTNOHAND;
2568 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2569 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2573 /* XXX: Don't preclude handling different sized sigset_t's. */
2574 if (sigsetsize != sizeof(sigset_t))
2577 if (copy_from_user(&newset, unewset, sizeof(newset)))
2579 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2581 spin_lock_irq(¤t->sighand->siglock);
2582 current->saved_sigmask = current->blocked;
2583 current->blocked = newset;
2584 recalc_sigpending();
2585 spin_unlock_irq(¤t->sighand->siglock);
2587 current->state = TASK_INTERRUPTIBLE;
2589 set_thread_flag(TIF_RESTORE_SIGMASK);
2590 return -ERESTARTNOHAND;
2592 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2594 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2599 void __init signals_init(void)
2601 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);