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 if (unlikely(!list_empty(&q->list))) {
1281 * If an SI_TIMER entry is already queue just increment
1282 * the overrun count.
1285 BUG_ON(q->info.si_code != SI_TIMER);
1286 q->info.si_overrun++;
1290 if (sig_ignored(t, sig))
1293 signalfd_notify(t, sig);
1294 list_add_tail(&q->list, &pending->list);
1295 sigaddset(&pending->signal, sig);
1299 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1301 unsigned long flags;
1304 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1307 * The rcu based delayed sighand destroy makes it possible to
1308 * run this without tasklist lock held. The task struct itself
1309 * cannot go away as create_timer did get_task_struct().
1311 * We return -1, when the task is marked exiting, so
1312 * 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);
1332 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1334 unsigned long flags;
1337 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1339 read_lock(&tasklist_lock);
1340 /* Since it_lock is held, p->sighand cannot be NULL. */
1341 spin_lock_irqsave(&p->sighand->siglock, flags);
1342 handle_stop_signal(sig, p);
1344 ret = do_send_sigqueue(sig, q, p, &p->signal->shared_pending);
1346 __group_complete_signal(sig, p);
1348 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1349 read_unlock(&tasklist_lock);
1354 * Wake up any threads in the parent blocked in wait* syscalls.
1356 static inline void __wake_up_parent(struct task_struct *p,
1357 struct task_struct *parent)
1359 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1363 * Let a parent know about the death of a child.
1364 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1367 void do_notify_parent(struct task_struct *tsk, int sig)
1369 struct siginfo info;
1370 unsigned long flags;
1371 struct sighand_struct *psig;
1375 /* do_notify_parent_cldstop should have been called instead. */
1376 BUG_ON(task_is_stopped_or_traced(tsk));
1378 BUG_ON(!tsk->ptrace &&
1379 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1381 info.si_signo = sig;
1384 * we are under tasklist_lock here so our parent is tied to
1385 * us and cannot exit and release its namespace.
1387 * the only it can is to switch its nsproxy with sys_unshare,
1388 * bu uncharing pid namespaces is not allowed, so we'll always
1389 * see relevant namespace
1391 * write_lock() currently calls preempt_disable() which is the
1392 * same as rcu_read_lock(), but according to Oleg, this is not
1393 * correct to rely on this
1396 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1399 info.si_uid = tsk->uid;
1401 /* FIXME: find out whether or not this is supposed to be c*time. */
1402 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1403 tsk->signal->utime));
1404 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1405 tsk->signal->stime));
1407 info.si_status = tsk->exit_code & 0x7f;
1408 if (tsk->exit_code & 0x80)
1409 info.si_code = CLD_DUMPED;
1410 else if (tsk->exit_code & 0x7f)
1411 info.si_code = CLD_KILLED;
1413 info.si_code = CLD_EXITED;
1414 info.si_status = tsk->exit_code >> 8;
1417 psig = tsk->parent->sighand;
1418 spin_lock_irqsave(&psig->siglock, flags);
1419 if (!tsk->ptrace && sig == SIGCHLD &&
1420 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1421 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1423 * We are exiting and our parent doesn't care. POSIX.1
1424 * defines special semantics for setting SIGCHLD to SIG_IGN
1425 * or setting the SA_NOCLDWAIT flag: we should be reaped
1426 * automatically and not left for our parent's wait4 call.
1427 * Rather than having the parent do it as a magic kind of
1428 * signal handler, we just set this to tell do_exit that we
1429 * can be cleaned up without becoming a zombie. Note that
1430 * we still call __wake_up_parent in this case, because a
1431 * blocked sys_wait4 might now return -ECHILD.
1433 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1434 * is implementation-defined: we do (if you don't want
1435 * it, just use SIG_IGN instead).
1437 tsk->exit_signal = -1;
1438 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1441 if (valid_signal(sig) && sig > 0)
1442 __group_send_sig_info(sig, &info, tsk->parent);
1443 __wake_up_parent(tsk, tsk->parent);
1444 spin_unlock_irqrestore(&psig->siglock, flags);
1447 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1449 struct siginfo info;
1450 unsigned long flags;
1451 struct task_struct *parent;
1452 struct sighand_struct *sighand;
1454 if (tsk->ptrace & PT_PTRACED)
1455 parent = tsk->parent;
1457 tsk = tsk->group_leader;
1458 parent = tsk->real_parent;
1461 info.si_signo = SIGCHLD;
1464 * see comment in do_notify_parent() abot the following 3 lines
1467 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1470 info.si_uid = tsk->uid;
1472 /* FIXME: find out whether or not this is supposed to be c*time. */
1473 info.si_utime = cputime_to_jiffies(tsk->utime);
1474 info.si_stime = cputime_to_jiffies(tsk->stime);
1479 info.si_status = SIGCONT;
1482 info.si_status = tsk->signal->group_exit_code & 0x7f;
1485 info.si_status = tsk->exit_code & 0x7f;
1491 sighand = parent->sighand;
1492 spin_lock_irqsave(&sighand->siglock, flags);
1493 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1494 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1495 __group_send_sig_info(SIGCHLD, &info, parent);
1497 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1499 __wake_up_parent(tsk, parent);
1500 spin_unlock_irqrestore(&sighand->siglock, flags);
1503 static inline int may_ptrace_stop(void)
1505 if (!likely(current->ptrace & PT_PTRACED))
1508 * Are we in the middle of do_coredump?
1509 * If so and our tracer is also part of the coredump stopping
1510 * is a deadlock situation, and pointless because our tracer
1511 * is dead so don't allow us to stop.
1512 * If SIGKILL was already sent before the caller unlocked
1513 * ->siglock we must see ->core_waiters != 0. Otherwise it
1514 * is safe to enter schedule().
1516 if (unlikely(current->mm->core_waiters) &&
1517 unlikely(current->mm == current->parent->mm))
1524 * Return nonzero if there is a SIGKILL that should be waking us up.
1525 * Called with the siglock held.
1527 static int sigkill_pending(struct task_struct *tsk)
1529 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1530 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1531 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1535 * This must be called with current->sighand->siglock held.
1537 * This should be the path for all ptrace stops.
1538 * We always set current->last_siginfo while stopped here.
1539 * That makes it a way to test a stopped process for
1540 * being ptrace-stopped vs being job-control-stopped.
1542 * If we actually decide not to stop at all because the tracer
1543 * is gone, we keep current->exit_code unless clear_code.
1545 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1549 if (arch_ptrace_stop_needed(exit_code, info)) {
1551 * The arch code has something special to do before a
1552 * ptrace stop. This is allowed to block, e.g. for faults
1553 * on user stack pages. We can't keep the siglock while
1554 * calling arch_ptrace_stop, so we must release it now.
1555 * To preserve proper semantics, we must do this before
1556 * any signal bookkeeping like checking group_stop_count.
1557 * Meanwhile, a SIGKILL could come in before we retake the
1558 * siglock. That must prevent us from sleeping in TASK_TRACED.
1559 * So after regaining the lock, we must check for SIGKILL.
1561 spin_unlock_irq(¤t->sighand->siglock);
1562 arch_ptrace_stop(exit_code, info);
1563 spin_lock_irq(¤t->sighand->siglock);
1564 killed = sigkill_pending(current);
1568 * If there is a group stop in progress,
1569 * we must participate in the bookkeeping.
1571 if (current->signal->group_stop_count > 0)
1572 --current->signal->group_stop_count;
1574 current->last_siginfo = info;
1575 current->exit_code = exit_code;
1577 /* Let the debugger run. */
1578 __set_current_state(TASK_TRACED);
1579 spin_unlock_irq(¤t->sighand->siglock);
1580 read_lock(&tasklist_lock);
1581 if (!unlikely(killed) && may_ptrace_stop()) {
1582 do_notify_parent_cldstop(current, CLD_TRAPPED);
1583 read_unlock(&tasklist_lock);
1587 * By the time we got the lock, our tracer went away.
1588 * Don't drop the lock yet, another tracer may come.
1590 __set_current_state(TASK_RUNNING);
1592 current->exit_code = 0;
1593 read_unlock(&tasklist_lock);
1597 * While in TASK_TRACED, we were considered "frozen enough".
1598 * Now that we woke up, it's crucial if we're supposed to be
1599 * frozen that we freeze now before running anything substantial.
1604 * We are back. Now reacquire the siglock before touching
1605 * last_siginfo, so that we are sure to have synchronized with
1606 * any signal-sending on another CPU that wants to examine it.
1608 spin_lock_irq(¤t->sighand->siglock);
1609 current->last_siginfo = NULL;
1612 * Queued signals ignored us while we were stopped for tracing.
1613 * So check for any that we should take before resuming user mode.
1614 * This sets TIF_SIGPENDING, but never clears it.
1616 recalc_sigpending_tsk(current);
1619 void ptrace_notify(int exit_code)
1623 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1625 memset(&info, 0, sizeof info);
1626 info.si_signo = SIGTRAP;
1627 info.si_code = exit_code;
1628 info.si_pid = task_pid_vnr(current);
1629 info.si_uid = current->uid;
1631 /* Let the debugger run. */
1632 spin_lock_irq(¤t->sighand->siglock);
1633 ptrace_stop(exit_code, 1, &info);
1634 spin_unlock_irq(¤t->sighand->siglock);
1638 finish_stop(int stop_count)
1641 * If there are no other threads in the group, or if there is
1642 * a group stop in progress and we are the last to stop,
1643 * report to the parent. When ptraced, every thread reports itself.
1645 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1646 read_lock(&tasklist_lock);
1647 do_notify_parent_cldstop(current, CLD_STOPPED);
1648 read_unlock(&tasklist_lock);
1653 } while (try_to_freeze());
1655 * Now we don't run again until continued.
1657 current->exit_code = 0;
1661 * This performs the stopping for SIGSTOP and other stop signals.
1662 * We have to stop all threads in the thread group.
1663 * Returns nonzero if we've actually stopped and released the siglock.
1664 * Returns zero if we didn't stop and still hold the siglock.
1666 static int do_signal_stop(int signr)
1668 struct signal_struct *sig = current->signal;
1671 if (sig->group_stop_count > 0) {
1673 * There is a group stop in progress. We don't need to
1674 * start another one.
1676 stop_count = --sig->group_stop_count;
1678 struct task_struct *t;
1680 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1681 unlikely(signal_group_exit(sig)))
1684 * There is no group stop already in progress.
1685 * We must initiate one now.
1687 sig->group_exit_code = signr;
1690 for (t = next_thread(current); t != current; t = next_thread(t))
1692 * Setting state to TASK_STOPPED for a group
1693 * stop is always done with the siglock held,
1694 * so this check has no races.
1696 if (!(t->flags & PF_EXITING) &&
1697 !task_is_stopped_or_traced(t)) {
1699 signal_wake_up(t, 0);
1701 sig->group_stop_count = stop_count;
1704 if (stop_count == 0)
1705 sig->flags = SIGNAL_STOP_STOPPED;
1706 current->exit_code = sig->group_exit_code;
1707 __set_current_state(TASK_STOPPED);
1709 spin_unlock_irq(¤t->sighand->siglock);
1710 finish_stop(stop_count);
1714 static int ptrace_signal(int signr, siginfo_t *info,
1715 struct pt_regs *regs, void *cookie)
1717 if (!(current->ptrace & PT_PTRACED))
1720 ptrace_signal_deliver(regs, cookie);
1722 /* Let the debugger run. */
1723 ptrace_stop(signr, 0, info);
1725 /* We're back. Did the debugger cancel the sig? */
1726 signr = current->exit_code;
1730 current->exit_code = 0;
1732 /* Update the siginfo structure if the signal has
1733 changed. If the debugger wanted something
1734 specific in the siginfo structure then it should
1735 have updated *info via PTRACE_SETSIGINFO. */
1736 if (signr != info->si_signo) {
1737 info->si_signo = signr;
1739 info->si_code = SI_USER;
1740 info->si_pid = task_pid_vnr(current->parent);
1741 info->si_uid = current->parent->uid;
1744 /* If the (new) signal is now blocked, requeue it. */
1745 if (sigismember(¤t->blocked, signr)) {
1746 specific_send_sig_info(signr, info, current);
1753 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1754 struct pt_regs *regs, void *cookie)
1756 sigset_t *mask = ¤t->blocked;
1761 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1762 * While in TASK_STOPPED, we were considered "frozen enough".
1763 * Now that we woke up, it's crucial if we're supposed to be
1764 * frozen that we freeze now before running anything substantial.
1768 spin_lock_irq(¤t->sighand->siglock);
1770 if (unlikely(current->signal->flags & SIGNAL_CLD_MASK)) {
1771 int why = (current->signal->flags & SIGNAL_STOP_CONTINUED)
1772 ? CLD_CONTINUED : CLD_STOPPED;
1773 current->signal->flags &= ~SIGNAL_CLD_MASK;
1774 spin_unlock_irq(¤t->sighand->siglock);
1776 read_lock(&tasklist_lock);
1777 do_notify_parent_cldstop(current->group_leader, why);
1778 read_unlock(&tasklist_lock);
1783 struct k_sigaction *ka;
1785 if (unlikely(current->signal->group_stop_count > 0) &&
1789 signr = dequeue_signal(current, mask, info);
1792 break; /* will return 0 */
1794 if (signr != SIGKILL) {
1795 signr = ptrace_signal(signr, info, regs, cookie);
1800 ka = ¤t->sighand->action[signr-1];
1801 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1803 if (ka->sa.sa_handler != SIG_DFL) {
1804 /* Run the handler. */
1807 if (ka->sa.sa_flags & SA_ONESHOT)
1808 ka->sa.sa_handler = SIG_DFL;
1810 break; /* will return non-zero "signr" value */
1814 * Now we are doing the default action for this signal.
1816 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1820 * Global init gets no signals it doesn't want.
1822 if (is_global_init(current))
1825 if (sig_kernel_stop(signr)) {
1827 * The default action is to stop all threads in
1828 * the thread group. The job control signals
1829 * do nothing in an orphaned pgrp, but SIGSTOP
1830 * always works. Note that siglock needs to be
1831 * dropped during the call to is_orphaned_pgrp()
1832 * because of lock ordering with tasklist_lock.
1833 * This allows an intervening SIGCONT to be posted.
1834 * We need to check for that and bail out if necessary.
1836 if (signr != SIGSTOP) {
1837 spin_unlock_irq(¤t->sighand->siglock);
1839 /* signals can be posted during this window */
1841 if (is_current_pgrp_orphaned())
1844 spin_lock_irq(¤t->sighand->siglock);
1847 if (likely(do_signal_stop(signr))) {
1848 /* It released the siglock. */
1853 * We didn't actually stop, due to a race
1854 * with SIGCONT or something like that.
1859 spin_unlock_irq(¤t->sighand->siglock);
1862 * Anything else is fatal, maybe with a core dump.
1864 current->flags |= PF_SIGNALED;
1865 if ((signr != SIGKILL) && print_fatal_signals)
1866 print_fatal_signal(regs, signr);
1867 if (sig_kernel_coredump(signr)) {
1869 * If it was able to dump core, this kills all
1870 * other threads in the group and synchronizes with
1871 * their demise. If we lost the race with another
1872 * thread getting here, it set group_exit_code
1873 * first and our do_group_exit call below will use
1874 * that value and ignore the one we pass it.
1876 do_coredump((long)signr, signr, regs);
1880 * Death signals, no core dump.
1882 do_group_exit(signr);
1885 spin_unlock_irq(¤t->sighand->siglock);
1889 void exit_signals(struct task_struct *tsk)
1892 struct task_struct *t;
1894 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1895 tsk->flags |= PF_EXITING;
1899 spin_lock_irq(&tsk->sighand->siglock);
1901 * From now this task is not visible for group-wide signals,
1902 * see wants_signal(), do_signal_stop().
1904 tsk->flags |= PF_EXITING;
1905 if (!signal_pending(tsk))
1908 /* It could be that __group_complete_signal() choose us to
1909 * notify about group-wide signal. Another thread should be
1910 * woken now to take the signal since we will not.
1912 for (t = tsk; (t = next_thread(t)) != tsk; )
1913 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1914 recalc_sigpending_and_wake(t);
1916 if (unlikely(tsk->signal->group_stop_count) &&
1917 !--tsk->signal->group_stop_count) {
1918 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1922 spin_unlock_irq(&tsk->sighand->siglock);
1924 if (unlikely(group_stop)) {
1925 read_lock(&tasklist_lock);
1926 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1927 read_unlock(&tasklist_lock);
1931 EXPORT_SYMBOL(recalc_sigpending);
1932 EXPORT_SYMBOL_GPL(dequeue_signal);
1933 EXPORT_SYMBOL(flush_signals);
1934 EXPORT_SYMBOL(force_sig);
1935 EXPORT_SYMBOL(kill_proc);
1936 EXPORT_SYMBOL(ptrace_notify);
1937 EXPORT_SYMBOL(send_sig);
1938 EXPORT_SYMBOL(send_sig_info);
1939 EXPORT_SYMBOL(sigprocmask);
1940 EXPORT_SYMBOL(block_all_signals);
1941 EXPORT_SYMBOL(unblock_all_signals);
1945 * System call entry points.
1948 asmlinkage long sys_restart_syscall(void)
1950 struct restart_block *restart = ¤t_thread_info()->restart_block;
1951 return restart->fn(restart);
1954 long do_no_restart_syscall(struct restart_block *param)
1960 * We don't need to get the kernel lock - this is all local to this
1961 * particular thread.. (and that's good, because this is _heavily_
1962 * used by various programs)
1966 * This is also useful for kernel threads that want to temporarily
1967 * (or permanently) block certain signals.
1969 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1970 * interface happily blocks "unblockable" signals like SIGKILL
1973 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1977 spin_lock_irq(¤t->sighand->siglock);
1979 *oldset = current->blocked;
1984 sigorsets(¤t->blocked, ¤t->blocked, set);
1987 signandsets(¤t->blocked, ¤t->blocked, set);
1990 current->blocked = *set;
1995 recalc_sigpending();
1996 spin_unlock_irq(¤t->sighand->siglock);
2002 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2004 int error = -EINVAL;
2005 sigset_t old_set, new_set;
2007 /* XXX: Don't preclude handling different sized sigset_t's. */
2008 if (sigsetsize != sizeof(sigset_t))
2013 if (copy_from_user(&new_set, set, sizeof(*set)))
2015 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2017 error = sigprocmask(how, &new_set, &old_set);
2023 spin_lock_irq(¤t->sighand->siglock);
2024 old_set = current->blocked;
2025 spin_unlock_irq(¤t->sighand->siglock);
2029 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2037 long do_sigpending(void __user *set, unsigned long sigsetsize)
2039 long error = -EINVAL;
2042 if (sigsetsize > sizeof(sigset_t))
2045 spin_lock_irq(¤t->sighand->siglock);
2046 sigorsets(&pending, ¤t->pending.signal,
2047 ¤t->signal->shared_pending.signal);
2048 spin_unlock_irq(¤t->sighand->siglock);
2050 /* Outside the lock because only this thread touches it. */
2051 sigandsets(&pending, ¤t->blocked, &pending);
2054 if (!copy_to_user(set, &pending, sigsetsize))
2062 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2064 return do_sigpending(set, sigsetsize);
2067 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2069 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2073 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2075 if (from->si_code < 0)
2076 return __copy_to_user(to, from, sizeof(siginfo_t))
2079 * If you change siginfo_t structure, please be sure
2080 * this code is fixed accordingly.
2081 * Please remember to update the signalfd_copyinfo() function
2082 * inside fs/signalfd.c too, in case siginfo_t changes.
2083 * It should never copy any pad contained in the structure
2084 * to avoid security leaks, but must copy the generic
2085 * 3 ints plus the relevant union member.
2087 err = __put_user(from->si_signo, &to->si_signo);
2088 err |= __put_user(from->si_errno, &to->si_errno);
2089 err |= __put_user((short)from->si_code, &to->si_code);
2090 switch (from->si_code & __SI_MASK) {
2092 err |= __put_user(from->si_pid, &to->si_pid);
2093 err |= __put_user(from->si_uid, &to->si_uid);
2096 err |= __put_user(from->si_tid, &to->si_tid);
2097 err |= __put_user(from->si_overrun, &to->si_overrun);
2098 err |= __put_user(from->si_ptr, &to->si_ptr);
2101 err |= __put_user(from->si_band, &to->si_band);
2102 err |= __put_user(from->si_fd, &to->si_fd);
2105 err |= __put_user(from->si_addr, &to->si_addr);
2106 #ifdef __ARCH_SI_TRAPNO
2107 err |= __put_user(from->si_trapno, &to->si_trapno);
2111 err |= __put_user(from->si_pid, &to->si_pid);
2112 err |= __put_user(from->si_uid, &to->si_uid);
2113 err |= __put_user(from->si_status, &to->si_status);
2114 err |= __put_user(from->si_utime, &to->si_utime);
2115 err |= __put_user(from->si_stime, &to->si_stime);
2117 case __SI_RT: /* This is not generated by the kernel as of now. */
2118 case __SI_MESGQ: /* But this is */
2119 err |= __put_user(from->si_pid, &to->si_pid);
2120 err |= __put_user(from->si_uid, &to->si_uid);
2121 err |= __put_user(from->si_ptr, &to->si_ptr);
2123 default: /* this is just in case for now ... */
2124 err |= __put_user(from->si_pid, &to->si_pid);
2125 err |= __put_user(from->si_uid, &to->si_uid);
2134 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2135 siginfo_t __user *uinfo,
2136 const struct timespec __user *uts,
2145 /* XXX: Don't preclude handling different sized sigset_t's. */
2146 if (sigsetsize != sizeof(sigset_t))
2149 if (copy_from_user(&these, uthese, sizeof(these)))
2153 * Invert the set of allowed signals to get those we
2156 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2160 if (copy_from_user(&ts, uts, sizeof(ts)))
2162 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2167 spin_lock_irq(¤t->sighand->siglock);
2168 sig = dequeue_signal(current, &these, &info);
2170 timeout = MAX_SCHEDULE_TIMEOUT;
2172 timeout = (timespec_to_jiffies(&ts)
2173 + (ts.tv_sec || ts.tv_nsec));
2176 /* None ready -- temporarily unblock those we're
2177 * interested while we are sleeping in so that we'll
2178 * be awakened when they arrive. */
2179 current->real_blocked = current->blocked;
2180 sigandsets(¤t->blocked, ¤t->blocked, &these);
2181 recalc_sigpending();
2182 spin_unlock_irq(¤t->sighand->siglock);
2184 timeout = schedule_timeout_interruptible(timeout);
2186 spin_lock_irq(¤t->sighand->siglock);
2187 sig = dequeue_signal(current, &these, &info);
2188 current->blocked = current->real_blocked;
2189 siginitset(¤t->real_blocked, 0);
2190 recalc_sigpending();
2193 spin_unlock_irq(¤t->sighand->siglock);
2198 if (copy_siginfo_to_user(uinfo, &info))
2211 sys_kill(int pid, int sig)
2213 struct siginfo info;
2215 info.si_signo = sig;
2217 info.si_code = SI_USER;
2218 info.si_pid = task_tgid_vnr(current);
2219 info.si_uid = current->uid;
2221 return kill_something_info(sig, &info, pid);
2224 static int do_tkill(int tgid, int pid, int sig)
2227 struct siginfo info;
2228 struct task_struct *p;
2231 info.si_signo = sig;
2233 info.si_code = SI_TKILL;
2234 info.si_pid = task_tgid_vnr(current);
2235 info.si_uid = current->uid;
2237 read_lock(&tasklist_lock);
2238 p = find_task_by_vpid(pid);
2239 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2240 error = check_kill_permission(sig, &info, p);
2242 * The null signal is a permissions and process existence
2243 * probe. No signal is actually delivered.
2245 if (!error && sig && p->sighand) {
2246 spin_lock_irq(&p->sighand->siglock);
2247 handle_stop_signal(sig, p);
2248 error = specific_send_sig_info(sig, &info, p);
2249 spin_unlock_irq(&p->sighand->siglock);
2252 read_unlock(&tasklist_lock);
2258 * sys_tgkill - send signal to one specific thread
2259 * @tgid: the thread group ID of the thread
2260 * @pid: the PID of the thread
2261 * @sig: signal to be sent
2263 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2264 * exists but it's not belonging to the target process anymore. This
2265 * method solves the problem of threads exiting and PIDs getting reused.
2267 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2269 /* This is only valid for single tasks */
2270 if (pid <= 0 || tgid <= 0)
2273 return do_tkill(tgid, pid, sig);
2277 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2280 sys_tkill(int pid, int sig)
2282 /* This is only valid for single tasks */
2286 return do_tkill(0, pid, sig);
2290 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2294 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2297 /* Not even root can pretend to send signals from the kernel.
2298 Nor can they impersonate a kill(), which adds source info. */
2299 if (info.si_code >= 0)
2301 info.si_signo = sig;
2303 /* POSIX.1b doesn't mention process groups. */
2304 return kill_proc_info(sig, &info, pid);
2307 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2309 struct task_struct *t = current;
2310 struct k_sigaction *k;
2313 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2316 k = &t->sighand->action[sig-1];
2318 spin_lock_irq(¤t->sighand->siglock);
2323 sigdelsetmask(&act->sa.sa_mask,
2324 sigmask(SIGKILL) | sigmask(SIGSTOP));
2328 * "Setting a signal action to SIG_IGN for a signal that is
2329 * pending shall cause the pending signal to be discarded,
2330 * whether or not it is blocked."
2332 * "Setting a signal action to SIG_DFL for a signal that is
2333 * pending and whose default action is to ignore the signal
2334 * (for example, SIGCHLD), shall cause the pending signal to
2335 * be discarded, whether or not it is blocked"
2337 if (__sig_ignored(t, sig)) {
2339 sigaddset(&mask, sig);
2340 rm_from_queue_full(&mask, &t->signal->shared_pending);
2342 rm_from_queue_full(&mask, &t->pending);
2344 } while (t != current);
2348 spin_unlock_irq(¤t->sighand->siglock);
2353 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2359 oss.ss_sp = (void __user *) current->sas_ss_sp;
2360 oss.ss_size = current->sas_ss_size;
2361 oss.ss_flags = sas_ss_flags(sp);
2370 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2371 || __get_user(ss_sp, &uss->ss_sp)
2372 || __get_user(ss_flags, &uss->ss_flags)
2373 || __get_user(ss_size, &uss->ss_size))
2377 if (on_sig_stack(sp))
2383 * Note - this code used to test ss_flags incorrectly
2384 * old code may have been written using ss_flags==0
2385 * to mean ss_flags==SS_ONSTACK (as this was the only
2386 * way that worked) - this fix preserves that older
2389 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2392 if (ss_flags == SS_DISABLE) {
2397 if (ss_size < MINSIGSTKSZ)
2401 current->sas_ss_sp = (unsigned long) ss_sp;
2402 current->sas_ss_size = ss_size;
2407 if (copy_to_user(uoss, &oss, sizeof(oss)))
2416 #ifdef __ARCH_WANT_SYS_SIGPENDING
2419 sys_sigpending(old_sigset_t __user *set)
2421 return do_sigpending(set, sizeof(*set));
2426 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2427 /* Some platforms have their own version with special arguments others
2428 support only sys_rt_sigprocmask. */
2431 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2434 old_sigset_t old_set, new_set;
2438 if (copy_from_user(&new_set, set, sizeof(*set)))
2440 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2442 spin_lock_irq(¤t->sighand->siglock);
2443 old_set = current->blocked.sig[0];
2451 sigaddsetmask(¤t->blocked, new_set);
2454 sigdelsetmask(¤t->blocked, new_set);
2457 current->blocked.sig[0] = new_set;
2461 recalc_sigpending();
2462 spin_unlock_irq(¤t->sighand->siglock);
2468 old_set = current->blocked.sig[0];
2471 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2478 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2480 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2482 sys_rt_sigaction(int sig,
2483 const struct sigaction __user *act,
2484 struct sigaction __user *oact,
2487 struct k_sigaction new_sa, old_sa;
2490 /* XXX: Don't preclude handling different sized sigset_t's. */
2491 if (sigsetsize != sizeof(sigset_t))
2495 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2499 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2502 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2508 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2510 #ifdef __ARCH_WANT_SYS_SGETMASK
2513 * For backwards compatibility. Functionality superseded by sigprocmask.
2519 return current->blocked.sig[0];
2523 sys_ssetmask(int newmask)
2527 spin_lock_irq(¤t->sighand->siglock);
2528 old = current->blocked.sig[0];
2530 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2532 recalc_sigpending();
2533 spin_unlock_irq(¤t->sighand->siglock);
2537 #endif /* __ARCH_WANT_SGETMASK */
2539 #ifdef __ARCH_WANT_SYS_SIGNAL
2541 * For backwards compatibility. Functionality superseded by sigaction.
2543 asmlinkage unsigned long
2544 sys_signal(int sig, __sighandler_t handler)
2546 struct k_sigaction new_sa, old_sa;
2549 new_sa.sa.sa_handler = handler;
2550 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2551 sigemptyset(&new_sa.sa.sa_mask);
2553 ret = do_sigaction(sig, &new_sa, &old_sa);
2555 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2557 #endif /* __ARCH_WANT_SYS_SIGNAL */
2559 #ifdef __ARCH_WANT_SYS_PAUSE
2564 current->state = TASK_INTERRUPTIBLE;
2566 return -ERESTARTNOHAND;
2571 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2572 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2576 /* XXX: Don't preclude handling different sized sigset_t's. */
2577 if (sigsetsize != sizeof(sigset_t))
2580 if (copy_from_user(&newset, unewset, sizeof(newset)))
2582 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2584 spin_lock_irq(¤t->sighand->siglock);
2585 current->saved_sigmask = current->blocked;
2586 current->blocked = newset;
2587 recalc_sigpending();
2588 spin_unlock_irq(¤t->sighand->siglock);
2590 current->state = TASK_INTERRUPTIBLE;
2592 set_thread_flag(TIF_RESTORE_SIGMASK);
2593 return -ERESTARTNOHAND;
2595 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2597 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2602 void __init signals_init(void)
2604 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);