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 signal_struct *signal = p->signal;
846 struct task_struct *t;
849 * Now find a thread we can wake up to take the signal off the queue.
851 * If the main thread wants the signal, it gets first crack.
852 * Probably the least surprising to the average bear.
854 if (wants_signal(sig, p))
856 else if (thread_group_empty(p))
858 * There is just one thread and it does not need to be woken.
859 * It will dequeue unblocked signals before it runs again.
864 * Otherwise try to find a suitable thread.
866 t = signal->curr_target;
868 /* restart balancing at this thread */
869 t = signal->curr_target = p;
871 while (!wants_signal(sig, t)) {
873 if (t == signal->curr_target)
875 * No thread needs to be woken.
876 * Any eligible threads will see
877 * the signal in the queue soon.
881 signal->curr_target = t;
885 * Found a killable thread. If the signal will be fatal,
886 * then start taking the whole group down immediately.
888 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
889 !sigismember(&t->real_blocked, sig) &&
890 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
892 * This signal will be fatal to the whole group.
894 if (!sig_kernel_coredump(sig)) {
896 * Start a group exit and wake everybody up.
897 * This way we don't have other threads
898 * running and doing things after a slower
899 * thread has the fatal signal pending.
901 signal->flags = SIGNAL_GROUP_EXIT;
902 signal->group_exit_code = sig;
903 signal->group_stop_count = 0;
906 sigaddset(&t->pending.signal, SIGKILL);
907 signal_wake_up(t, 1);
908 } while_each_thread(p, t);
914 * The signal is already in the shared-pending queue.
915 * Tell the chosen thread to wake up and dequeue it.
917 signal_wake_up(t, sig == SIGKILL);
922 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
926 assert_spin_locked(&p->sighand->siglock);
927 handle_stop_signal(sig, p);
930 * Put this signal on the shared-pending queue, or fail with EAGAIN.
931 * We always use the shared queue for process-wide signals,
932 * to avoid several races.
934 ret = send_signal(sig, info, p, &p->signal->shared_pending);
938 __group_complete_signal(sig, p);
943 * Nuke all other threads in the group.
945 void zap_other_threads(struct task_struct *p)
947 struct task_struct *t;
949 p->signal->group_stop_count = 0;
951 for (t = next_thread(p); t != p; t = next_thread(t)) {
953 * Don't bother with already dead threads
958 /* SIGKILL will be handled before any pending SIGSTOP */
959 sigaddset(&t->pending.signal, SIGKILL);
960 signal_wake_up(t, 1);
964 int __fatal_signal_pending(struct task_struct *tsk)
966 return sigismember(&tsk->pending.signal, SIGKILL);
968 EXPORT_SYMBOL(__fatal_signal_pending);
970 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
972 struct sighand_struct *sighand;
976 sighand = rcu_dereference(tsk->sighand);
977 if (unlikely(sighand == NULL))
980 spin_lock_irqsave(&sighand->siglock, *flags);
981 if (likely(sighand == tsk->sighand))
983 spin_unlock_irqrestore(&sighand->siglock, *flags);
990 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
995 ret = check_kill_permission(sig, info, p);
999 if (lock_task_sighand(p, &flags)) {
1000 ret = __group_send_sig_info(sig, info, p);
1001 unlock_task_sighand(p, &flags);
1009 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1010 * control characters do (^C, ^Z etc)
1013 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1015 struct task_struct *p = NULL;
1016 int retval, success;
1020 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1021 int err = group_send_sig_info(sig, info, p);
1024 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1025 return success ? 0 : retval;
1028 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1031 struct task_struct *p;
1035 p = pid_task(pid, PIDTYPE_PID);
1037 error = group_send_sig_info(sig, info, p);
1038 if (unlikely(error == -ESRCH))
1040 * The task was unhashed in between, try again.
1041 * If it is dead, pid_task() will return NULL,
1042 * if we race with de_thread() it will find the
1053 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1057 error = kill_pid_info(sig, info, find_vpid(pid));
1062 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1063 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1064 uid_t uid, uid_t euid, u32 secid)
1067 struct task_struct *p;
1069 if (!valid_signal(sig))
1072 read_lock(&tasklist_lock);
1073 p = pid_task(pid, PIDTYPE_PID);
1078 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1079 && (euid != p->suid) && (euid != p->uid)
1080 && (uid != p->suid) && (uid != p->uid)) {
1084 ret = security_task_kill(p, info, sig, secid);
1087 if (sig && p->sighand) {
1088 unsigned long flags;
1089 spin_lock_irqsave(&p->sighand->siglock, flags);
1090 ret = __group_send_sig_info(sig, info, p);
1091 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1094 read_unlock(&tasklist_lock);
1097 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1100 * kill_something_info() interprets pid in interesting ways just like kill(2).
1102 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1103 * is probably wrong. Should make it like BSD or SYSV.
1106 static int kill_something_info(int sig, struct siginfo *info, int pid)
1112 ret = kill_pid_info(sig, info, find_vpid(pid));
1117 read_lock(&tasklist_lock);
1119 ret = __kill_pgrp_info(sig, info,
1120 pid ? find_vpid(-pid) : task_pgrp(current));
1122 int retval = 0, count = 0;
1123 struct task_struct * p;
1125 for_each_process(p) {
1126 if (p->pid > 1 && !same_thread_group(p, current)) {
1127 int err = group_send_sig_info(sig, info, p);
1133 ret = count ? retval : -ESRCH;
1135 read_unlock(&tasklist_lock);
1141 * These are for backward compatibility with the rest of the kernel source.
1145 * These two are the most common entry points. They send a signal
1146 * just to the specific thread.
1149 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1152 unsigned long flags;
1155 * Make sure legacy kernel users don't send in bad values
1156 * (normal paths check this in check_kill_permission).
1158 if (!valid_signal(sig))
1162 * We need the tasklist lock even for the specific
1163 * thread case (when we don't need to follow the group
1164 * lists) in order to avoid races with "p->sighand"
1165 * going away or changing from under us.
1167 read_lock(&tasklist_lock);
1168 spin_lock_irqsave(&p->sighand->siglock, flags);
1169 ret = specific_send_sig_info(sig, info, p);
1170 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1171 read_unlock(&tasklist_lock);
1175 #define __si_special(priv) \
1176 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1179 send_sig(int sig, struct task_struct *p, int priv)
1181 return send_sig_info(sig, __si_special(priv), p);
1185 force_sig(int sig, struct task_struct *p)
1187 force_sig_info(sig, SEND_SIG_PRIV, p);
1191 * When things go south during signal handling, we
1192 * will force a SIGSEGV. And if the signal that caused
1193 * the problem was already a SIGSEGV, we'll want to
1194 * make sure we don't even try to deliver the signal..
1197 force_sigsegv(int sig, struct task_struct *p)
1199 if (sig == SIGSEGV) {
1200 unsigned long flags;
1201 spin_lock_irqsave(&p->sighand->siglock, flags);
1202 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1203 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1205 force_sig(SIGSEGV, p);
1209 int kill_pgrp(struct pid *pid, int sig, int priv)
1213 read_lock(&tasklist_lock);
1214 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1215 read_unlock(&tasklist_lock);
1219 EXPORT_SYMBOL(kill_pgrp);
1221 int kill_pid(struct pid *pid, int sig, int priv)
1223 return kill_pid_info(sig, __si_special(priv), pid);
1225 EXPORT_SYMBOL(kill_pid);
1228 kill_proc(pid_t pid, int sig, int priv)
1233 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1239 * These functions support sending signals using preallocated sigqueue
1240 * structures. This is needed "because realtime applications cannot
1241 * afford to lose notifications of asynchronous events, like timer
1242 * expirations or I/O completions". In the case of Posix Timers
1243 * we allocate the sigqueue structure from the timer_create. If this
1244 * allocation fails we are able to report the failure to the application
1245 * with an EAGAIN error.
1248 struct sigqueue *sigqueue_alloc(void)
1252 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1253 q->flags |= SIGQUEUE_PREALLOC;
1257 void sigqueue_free(struct sigqueue *q)
1259 unsigned long flags;
1260 spinlock_t *lock = ¤t->sighand->siglock;
1262 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1264 * If the signal is still pending remove it from the
1265 * pending queue. We must hold ->siglock while testing
1266 * q->list to serialize with collect_signal().
1268 spin_lock_irqsave(lock, flags);
1269 if (!list_empty(&q->list))
1270 list_del_init(&q->list);
1271 spin_unlock_irqrestore(lock, flags);
1273 q->flags &= ~SIGQUEUE_PREALLOC;
1277 static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
1278 struct sigpending *pending)
1280 handle_stop_signal(sig, t);
1282 if (unlikely(!list_empty(&q->list))) {
1284 * If an SI_TIMER entry is already queue just increment
1285 * the overrun count.
1288 BUG_ON(q->info.si_code != SI_TIMER);
1289 q->info.si_overrun++;
1293 if (sig_ignored(t, sig))
1296 signalfd_notify(t, sig);
1297 list_add_tail(&q->list, &pending->list);
1298 sigaddset(&pending->signal, sig);
1302 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1304 unsigned long flags;
1307 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1310 * The rcu based delayed sighand destroy makes it possible to
1311 * run this without tasklist lock held. The task struct itself
1312 * cannot go away as create_timer did get_task_struct().
1314 * We return -1, when the task is marked exiting, so
1315 * posix_timer_event can redirect it to the group leader
1317 if (!likely(lock_task_sighand(p, &flags)))
1320 ret = do_send_sigqueue(sig, q, p, &p->pending);
1322 if (!sigismember(&p->blocked, sig))
1323 signal_wake_up(p, sig == SIGKILL);
1325 unlock_task_sighand(p, &flags);
1331 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1333 unsigned long flags;
1336 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1338 read_lock(&tasklist_lock);
1339 /* Since it_lock is held, p->sighand cannot be NULL. */
1340 spin_lock_irqsave(&p->sighand->siglock, flags);
1342 ret = do_send_sigqueue(sig, q, p, &p->signal->shared_pending);
1344 __group_complete_signal(sig, p);
1346 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1347 read_unlock(&tasklist_lock);
1352 * Wake up any threads in the parent blocked in wait* syscalls.
1354 static inline void __wake_up_parent(struct task_struct *p,
1355 struct task_struct *parent)
1357 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1361 * Let a parent know about the death of a child.
1362 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1365 void do_notify_parent(struct task_struct *tsk, int sig)
1367 struct siginfo info;
1368 unsigned long flags;
1369 struct sighand_struct *psig;
1373 /* do_notify_parent_cldstop should have been called instead. */
1374 BUG_ON(task_is_stopped_or_traced(tsk));
1376 BUG_ON(!tsk->ptrace &&
1377 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1379 info.si_signo = sig;
1382 * we are under tasklist_lock here so our parent is tied to
1383 * us and cannot exit and release its namespace.
1385 * the only it can is to switch its nsproxy with sys_unshare,
1386 * bu uncharing pid namespaces is not allowed, so we'll always
1387 * see relevant namespace
1389 * write_lock() currently calls preempt_disable() which is the
1390 * same as rcu_read_lock(), but according to Oleg, this is not
1391 * correct to rely on this
1394 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1397 info.si_uid = tsk->uid;
1399 /* FIXME: find out whether or not this is supposed to be c*time. */
1400 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1401 tsk->signal->utime));
1402 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1403 tsk->signal->stime));
1405 info.si_status = tsk->exit_code & 0x7f;
1406 if (tsk->exit_code & 0x80)
1407 info.si_code = CLD_DUMPED;
1408 else if (tsk->exit_code & 0x7f)
1409 info.si_code = CLD_KILLED;
1411 info.si_code = CLD_EXITED;
1412 info.si_status = tsk->exit_code >> 8;
1415 psig = tsk->parent->sighand;
1416 spin_lock_irqsave(&psig->siglock, flags);
1417 if (!tsk->ptrace && sig == SIGCHLD &&
1418 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1419 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1421 * We are exiting and our parent doesn't care. POSIX.1
1422 * defines special semantics for setting SIGCHLD to SIG_IGN
1423 * or setting the SA_NOCLDWAIT flag: we should be reaped
1424 * automatically and not left for our parent's wait4 call.
1425 * Rather than having the parent do it as a magic kind of
1426 * signal handler, we just set this to tell do_exit that we
1427 * can be cleaned up without becoming a zombie. Note that
1428 * we still call __wake_up_parent in this case, because a
1429 * blocked sys_wait4 might now return -ECHILD.
1431 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1432 * is implementation-defined: we do (if you don't want
1433 * it, just use SIG_IGN instead).
1435 tsk->exit_signal = -1;
1436 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1439 if (valid_signal(sig) && sig > 0)
1440 __group_send_sig_info(sig, &info, tsk->parent);
1441 __wake_up_parent(tsk, tsk->parent);
1442 spin_unlock_irqrestore(&psig->siglock, flags);
1445 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1447 struct siginfo info;
1448 unsigned long flags;
1449 struct task_struct *parent;
1450 struct sighand_struct *sighand;
1452 if (tsk->ptrace & PT_PTRACED)
1453 parent = tsk->parent;
1455 tsk = tsk->group_leader;
1456 parent = tsk->real_parent;
1459 info.si_signo = SIGCHLD;
1462 * see comment in do_notify_parent() abot the following 3 lines
1465 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1468 info.si_uid = tsk->uid;
1470 /* FIXME: find out whether or not this is supposed to be c*time. */
1471 info.si_utime = cputime_to_jiffies(tsk->utime);
1472 info.si_stime = cputime_to_jiffies(tsk->stime);
1477 info.si_status = SIGCONT;
1480 info.si_status = tsk->signal->group_exit_code & 0x7f;
1483 info.si_status = tsk->exit_code & 0x7f;
1489 sighand = parent->sighand;
1490 spin_lock_irqsave(&sighand->siglock, flags);
1491 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1492 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1493 __group_send_sig_info(SIGCHLD, &info, parent);
1495 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1497 __wake_up_parent(tsk, parent);
1498 spin_unlock_irqrestore(&sighand->siglock, flags);
1501 static inline int may_ptrace_stop(void)
1503 if (!likely(current->ptrace & PT_PTRACED))
1506 * Are we in the middle of do_coredump?
1507 * If so and our tracer is also part of the coredump stopping
1508 * is a deadlock situation, and pointless because our tracer
1509 * is dead so don't allow us to stop.
1510 * If SIGKILL was already sent before the caller unlocked
1511 * ->siglock we must see ->core_waiters != 0. Otherwise it
1512 * is safe to enter schedule().
1514 if (unlikely(current->mm->core_waiters) &&
1515 unlikely(current->mm == current->parent->mm))
1522 * Return nonzero if there is a SIGKILL that should be waking us up.
1523 * Called with the siglock held.
1525 static int sigkill_pending(struct task_struct *tsk)
1527 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1528 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1529 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1533 * This must be called with current->sighand->siglock held.
1535 * This should be the path for all ptrace stops.
1536 * We always set current->last_siginfo while stopped here.
1537 * That makes it a way to test a stopped process for
1538 * being ptrace-stopped vs being job-control-stopped.
1540 * If we actually decide not to stop at all because the tracer
1541 * is gone, we keep current->exit_code unless clear_code.
1543 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1547 if (arch_ptrace_stop_needed(exit_code, info)) {
1549 * The arch code has something special to do before a
1550 * ptrace stop. This is allowed to block, e.g. for faults
1551 * on user stack pages. We can't keep the siglock while
1552 * calling arch_ptrace_stop, so we must release it now.
1553 * To preserve proper semantics, we must do this before
1554 * any signal bookkeeping like checking group_stop_count.
1555 * Meanwhile, a SIGKILL could come in before we retake the
1556 * siglock. That must prevent us from sleeping in TASK_TRACED.
1557 * So after regaining the lock, we must check for SIGKILL.
1559 spin_unlock_irq(¤t->sighand->siglock);
1560 arch_ptrace_stop(exit_code, info);
1561 spin_lock_irq(¤t->sighand->siglock);
1562 killed = sigkill_pending(current);
1566 * If there is a group stop in progress,
1567 * we must participate in the bookkeeping.
1569 if (current->signal->group_stop_count > 0)
1570 --current->signal->group_stop_count;
1572 current->last_siginfo = info;
1573 current->exit_code = exit_code;
1575 /* Let the debugger run. */
1576 __set_current_state(TASK_TRACED);
1577 spin_unlock_irq(¤t->sighand->siglock);
1578 read_lock(&tasklist_lock);
1579 if (!unlikely(killed) && may_ptrace_stop()) {
1580 do_notify_parent_cldstop(current, CLD_TRAPPED);
1581 read_unlock(&tasklist_lock);
1585 * By the time we got the lock, our tracer went away.
1586 * Don't drop the lock yet, another tracer may come.
1588 __set_current_state(TASK_RUNNING);
1590 current->exit_code = 0;
1591 read_unlock(&tasklist_lock);
1595 * While in TASK_TRACED, we were considered "frozen enough".
1596 * Now that we woke up, it's crucial if we're supposed to be
1597 * frozen that we freeze now before running anything substantial.
1602 * We are back. Now reacquire the siglock before touching
1603 * last_siginfo, so that we are sure to have synchronized with
1604 * any signal-sending on another CPU that wants to examine it.
1606 spin_lock_irq(¤t->sighand->siglock);
1607 current->last_siginfo = NULL;
1610 * Queued signals ignored us while we were stopped for tracing.
1611 * So check for any that we should take before resuming user mode.
1612 * This sets TIF_SIGPENDING, but never clears it.
1614 recalc_sigpending_tsk(current);
1617 void ptrace_notify(int exit_code)
1621 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1623 memset(&info, 0, sizeof info);
1624 info.si_signo = SIGTRAP;
1625 info.si_code = exit_code;
1626 info.si_pid = task_pid_vnr(current);
1627 info.si_uid = current->uid;
1629 /* Let the debugger run. */
1630 spin_lock_irq(¤t->sighand->siglock);
1631 ptrace_stop(exit_code, 1, &info);
1632 spin_unlock_irq(¤t->sighand->siglock);
1636 finish_stop(int stop_count)
1639 * If there are no other threads in the group, or if there is
1640 * a group stop in progress and we are the last to stop,
1641 * report to the parent. When ptraced, every thread reports itself.
1643 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1644 read_lock(&tasklist_lock);
1645 do_notify_parent_cldstop(current, CLD_STOPPED);
1646 read_unlock(&tasklist_lock);
1651 } while (try_to_freeze());
1653 * Now we don't run again until continued.
1655 current->exit_code = 0;
1659 * This performs the stopping for SIGSTOP and other stop signals.
1660 * We have to stop all threads in the thread group.
1661 * Returns nonzero if we've actually stopped and released the siglock.
1662 * Returns zero if we didn't stop and still hold the siglock.
1664 static int do_signal_stop(int signr)
1666 struct signal_struct *sig = current->signal;
1669 if (sig->group_stop_count > 0) {
1671 * There is a group stop in progress. We don't need to
1672 * start another one.
1674 stop_count = --sig->group_stop_count;
1676 struct task_struct *t;
1678 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1679 unlikely(signal_group_exit(sig)))
1682 * There is no group stop already in progress.
1683 * We must initiate one now.
1685 sig->group_exit_code = signr;
1688 for (t = next_thread(current); t != current; t = next_thread(t))
1690 * Setting state to TASK_STOPPED for a group
1691 * stop is always done with the siglock held,
1692 * so this check has no races.
1694 if (!(t->flags & PF_EXITING) &&
1695 !task_is_stopped_or_traced(t)) {
1697 signal_wake_up(t, 0);
1699 sig->group_stop_count = stop_count;
1702 if (stop_count == 0)
1703 sig->flags = SIGNAL_STOP_STOPPED;
1704 current->exit_code = sig->group_exit_code;
1705 __set_current_state(TASK_STOPPED);
1707 spin_unlock_irq(¤t->sighand->siglock);
1708 finish_stop(stop_count);
1712 static int ptrace_signal(int signr, siginfo_t *info,
1713 struct pt_regs *regs, void *cookie)
1715 if (!(current->ptrace & PT_PTRACED))
1718 ptrace_signal_deliver(regs, cookie);
1720 /* Let the debugger run. */
1721 ptrace_stop(signr, 0, info);
1723 /* We're back. Did the debugger cancel the sig? */
1724 signr = current->exit_code;
1728 current->exit_code = 0;
1730 /* Update the siginfo structure if the signal has
1731 changed. If the debugger wanted something
1732 specific in the siginfo structure then it should
1733 have updated *info via PTRACE_SETSIGINFO. */
1734 if (signr != info->si_signo) {
1735 info->si_signo = signr;
1737 info->si_code = SI_USER;
1738 info->si_pid = task_pid_vnr(current->parent);
1739 info->si_uid = current->parent->uid;
1742 /* If the (new) signal is now blocked, requeue it. */
1743 if (sigismember(¤t->blocked, signr)) {
1744 specific_send_sig_info(signr, info, current);
1751 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1752 struct pt_regs *regs, void *cookie)
1754 struct sighand_struct *sighand = current->sighand;
1755 struct signal_struct *signal = current->signal;
1760 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1761 * While in TASK_STOPPED, we were considered "frozen enough".
1762 * Now that we woke up, it's crucial if we're supposed to be
1763 * frozen that we freeze now before running anything substantial.
1767 spin_lock_irq(&sighand->siglock);
1769 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1770 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1771 ? CLD_CONTINUED : CLD_STOPPED;
1772 signal->flags &= ~SIGNAL_CLD_MASK;
1773 spin_unlock_irq(&sighand->siglock);
1775 read_lock(&tasklist_lock);
1776 do_notify_parent_cldstop(current->group_leader, why);
1777 read_unlock(&tasklist_lock);
1782 struct k_sigaction *ka;
1784 if (unlikely(signal->group_stop_count > 0) &&
1788 signr = dequeue_signal(current, ¤t->blocked, info);
1790 break; /* will return 0 */
1792 if (signr != SIGKILL) {
1793 signr = ptrace_signal(signr, info, regs, cookie);
1798 ka = &sighand->action[signr-1];
1799 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1801 if (ka->sa.sa_handler != SIG_DFL) {
1802 /* Run the handler. */
1805 if (ka->sa.sa_flags & SA_ONESHOT)
1806 ka->sa.sa_handler = SIG_DFL;
1808 break; /* will return non-zero "signr" value */
1812 * Now we are doing the default action for this signal.
1814 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1818 * Global init gets no signals it doesn't want.
1820 if (is_global_init(current))
1823 if (sig_kernel_stop(signr)) {
1825 * The default action is to stop all threads in
1826 * the thread group. The job control signals
1827 * do nothing in an orphaned pgrp, but SIGSTOP
1828 * always works. Note that siglock needs to be
1829 * dropped during the call to is_orphaned_pgrp()
1830 * because of lock ordering with tasklist_lock.
1831 * This allows an intervening SIGCONT to be posted.
1832 * We need to check for that and bail out if necessary.
1834 if (signr != SIGSTOP) {
1835 spin_unlock_irq(&sighand->siglock);
1837 /* signals can be posted during this window */
1839 if (is_current_pgrp_orphaned())
1842 spin_lock_irq(&sighand->siglock);
1845 if (likely(do_signal_stop(signr))) {
1846 /* It released the siglock. */
1851 * We didn't actually stop, due to a race
1852 * with SIGCONT or something like that.
1857 spin_unlock_irq(&sighand->siglock);
1860 * Anything else is fatal, maybe with a core dump.
1862 current->flags |= PF_SIGNALED;
1863 if ((signr != SIGKILL) && print_fatal_signals)
1864 print_fatal_signal(regs, signr);
1865 if (sig_kernel_coredump(signr)) {
1867 * If it was able to dump core, this kills all
1868 * other threads in the group and synchronizes with
1869 * their demise. If we lost the race with another
1870 * thread getting here, it set group_exit_code
1871 * first and our do_group_exit call below will use
1872 * that value and ignore the one we pass it.
1874 do_coredump((long)signr, signr, regs);
1878 * Death signals, no core dump.
1880 do_group_exit(signr);
1883 spin_unlock_irq(&sighand->siglock);
1887 void exit_signals(struct task_struct *tsk)
1890 struct task_struct *t;
1892 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1893 tsk->flags |= PF_EXITING;
1897 spin_lock_irq(&tsk->sighand->siglock);
1899 * From now this task is not visible for group-wide signals,
1900 * see wants_signal(), do_signal_stop().
1902 tsk->flags |= PF_EXITING;
1903 if (!signal_pending(tsk))
1906 /* It could be that __group_complete_signal() choose us to
1907 * notify about group-wide signal. Another thread should be
1908 * woken now to take the signal since we will not.
1910 for (t = tsk; (t = next_thread(t)) != tsk; )
1911 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1912 recalc_sigpending_and_wake(t);
1914 if (unlikely(tsk->signal->group_stop_count) &&
1915 !--tsk->signal->group_stop_count) {
1916 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1920 spin_unlock_irq(&tsk->sighand->siglock);
1922 if (unlikely(group_stop)) {
1923 read_lock(&tasklist_lock);
1924 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1925 read_unlock(&tasklist_lock);
1929 EXPORT_SYMBOL(recalc_sigpending);
1930 EXPORT_SYMBOL_GPL(dequeue_signal);
1931 EXPORT_SYMBOL(flush_signals);
1932 EXPORT_SYMBOL(force_sig);
1933 EXPORT_SYMBOL(kill_proc);
1934 EXPORT_SYMBOL(ptrace_notify);
1935 EXPORT_SYMBOL(send_sig);
1936 EXPORT_SYMBOL(send_sig_info);
1937 EXPORT_SYMBOL(sigprocmask);
1938 EXPORT_SYMBOL(block_all_signals);
1939 EXPORT_SYMBOL(unblock_all_signals);
1943 * System call entry points.
1946 asmlinkage long sys_restart_syscall(void)
1948 struct restart_block *restart = ¤t_thread_info()->restart_block;
1949 return restart->fn(restart);
1952 long do_no_restart_syscall(struct restart_block *param)
1958 * We don't need to get the kernel lock - this is all local to this
1959 * particular thread.. (and that's good, because this is _heavily_
1960 * used by various programs)
1964 * This is also useful for kernel threads that want to temporarily
1965 * (or permanently) block certain signals.
1967 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1968 * interface happily blocks "unblockable" signals like SIGKILL
1971 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1975 spin_lock_irq(¤t->sighand->siglock);
1977 *oldset = current->blocked;
1982 sigorsets(¤t->blocked, ¤t->blocked, set);
1985 signandsets(¤t->blocked, ¤t->blocked, set);
1988 current->blocked = *set;
1993 recalc_sigpending();
1994 spin_unlock_irq(¤t->sighand->siglock);
2000 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2002 int error = -EINVAL;
2003 sigset_t old_set, new_set;
2005 /* XXX: Don't preclude handling different sized sigset_t's. */
2006 if (sigsetsize != sizeof(sigset_t))
2011 if (copy_from_user(&new_set, set, sizeof(*set)))
2013 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2015 error = sigprocmask(how, &new_set, &old_set);
2021 spin_lock_irq(¤t->sighand->siglock);
2022 old_set = current->blocked;
2023 spin_unlock_irq(¤t->sighand->siglock);
2027 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2035 long do_sigpending(void __user *set, unsigned long sigsetsize)
2037 long error = -EINVAL;
2040 if (sigsetsize > sizeof(sigset_t))
2043 spin_lock_irq(¤t->sighand->siglock);
2044 sigorsets(&pending, ¤t->pending.signal,
2045 ¤t->signal->shared_pending.signal);
2046 spin_unlock_irq(¤t->sighand->siglock);
2048 /* Outside the lock because only this thread touches it. */
2049 sigandsets(&pending, ¤t->blocked, &pending);
2052 if (!copy_to_user(set, &pending, sigsetsize))
2060 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2062 return do_sigpending(set, sigsetsize);
2065 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2067 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2071 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2073 if (from->si_code < 0)
2074 return __copy_to_user(to, from, sizeof(siginfo_t))
2077 * If you change siginfo_t structure, please be sure
2078 * this code is fixed accordingly.
2079 * Please remember to update the signalfd_copyinfo() function
2080 * inside fs/signalfd.c too, in case siginfo_t changes.
2081 * It should never copy any pad contained in the structure
2082 * to avoid security leaks, but must copy the generic
2083 * 3 ints plus the relevant union member.
2085 err = __put_user(from->si_signo, &to->si_signo);
2086 err |= __put_user(from->si_errno, &to->si_errno);
2087 err |= __put_user((short)from->si_code, &to->si_code);
2088 switch (from->si_code & __SI_MASK) {
2090 err |= __put_user(from->si_pid, &to->si_pid);
2091 err |= __put_user(from->si_uid, &to->si_uid);
2094 err |= __put_user(from->si_tid, &to->si_tid);
2095 err |= __put_user(from->si_overrun, &to->si_overrun);
2096 err |= __put_user(from->si_ptr, &to->si_ptr);
2099 err |= __put_user(from->si_band, &to->si_band);
2100 err |= __put_user(from->si_fd, &to->si_fd);
2103 err |= __put_user(from->si_addr, &to->si_addr);
2104 #ifdef __ARCH_SI_TRAPNO
2105 err |= __put_user(from->si_trapno, &to->si_trapno);
2109 err |= __put_user(from->si_pid, &to->si_pid);
2110 err |= __put_user(from->si_uid, &to->si_uid);
2111 err |= __put_user(from->si_status, &to->si_status);
2112 err |= __put_user(from->si_utime, &to->si_utime);
2113 err |= __put_user(from->si_stime, &to->si_stime);
2115 case __SI_RT: /* This is not generated by the kernel as of now. */
2116 case __SI_MESGQ: /* But this is */
2117 err |= __put_user(from->si_pid, &to->si_pid);
2118 err |= __put_user(from->si_uid, &to->si_uid);
2119 err |= __put_user(from->si_ptr, &to->si_ptr);
2121 default: /* this is just in case for now ... */
2122 err |= __put_user(from->si_pid, &to->si_pid);
2123 err |= __put_user(from->si_uid, &to->si_uid);
2132 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2133 siginfo_t __user *uinfo,
2134 const struct timespec __user *uts,
2143 /* XXX: Don't preclude handling different sized sigset_t's. */
2144 if (sigsetsize != sizeof(sigset_t))
2147 if (copy_from_user(&these, uthese, sizeof(these)))
2151 * Invert the set of allowed signals to get those we
2154 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2158 if (copy_from_user(&ts, uts, sizeof(ts)))
2160 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2165 spin_lock_irq(¤t->sighand->siglock);
2166 sig = dequeue_signal(current, &these, &info);
2168 timeout = MAX_SCHEDULE_TIMEOUT;
2170 timeout = (timespec_to_jiffies(&ts)
2171 + (ts.tv_sec || ts.tv_nsec));
2174 /* None ready -- temporarily unblock those we're
2175 * interested while we are sleeping in so that we'll
2176 * be awakened when they arrive. */
2177 current->real_blocked = current->blocked;
2178 sigandsets(¤t->blocked, ¤t->blocked, &these);
2179 recalc_sigpending();
2180 spin_unlock_irq(¤t->sighand->siglock);
2182 timeout = schedule_timeout_interruptible(timeout);
2184 spin_lock_irq(¤t->sighand->siglock);
2185 sig = dequeue_signal(current, &these, &info);
2186 current->blocked = current->real_blocked;
2187 siginitset(¤t->real_blocked, 0);
2188 recalc_sigpending();
2191 spin_unlock_irq(¤t->sighand->siglock);
2196 if (copy_siginfo_to_user(uinfo, &info))
2209 sys_kill(int pid, int sig)
2211 struct siginfo info;
2213 info.si_signo = sig;
2215 info.si_code = SI_USER;
2216 info.si_pid = task_tgid_vnr(current);
2217 info.si_uid = current->uid;
2219 return kill_something_info(sig, &info, pid);
2222 static int do_tkill(int tgid, int pid, int sig)
2225 struct siginfo info;
2226 struct task_struct *p;
2229 info.si_signo = sig;
2231 info.si_code = SI_TKILL;
2232 info.si_pid = task_tgid_vnr(current);
2233 info.si_uid = current->uid;
2235 read_lock(&tasklist_lock);
2236 p = find_task_by_vpid(pid);
2237 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2238 error = check_kill_permission(sig, &info, p);
2240 * The null signal is a permissions and process existence
2241 * probe. No signal is actually delivered.
2243 if (!error && sig && p->sighand) {
2244 spin_lock_irq(&p->sighand->siglock);
2245 handle_stop_signal(sig, p);
2246 error = specific_send_sig_info(sig, &info, p);
2247 spin_unlock_irq(&p->sighand->siglock);
2250 read_unlock(&tasklist_lock);
2256 * sys_tgkill - send signal to one specific thread
2257 * @tgid: the thread group ID of the thread
2258 * @pid: the PID of the thread
2259 * @sig: signal to be sent
2261 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2262 * exists but it's not belonging to the target process anymore. This
2263 * method solves the problem of threads exiting and PIDs getting reused.
2265 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2267 /* This is only valid for single tasks */
2268 if (pid <= 0 || tgid <= 0)
2271 return do_tkill(tgid, pid, sig);
2275 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2278 sys_tkill(int pid, int sig)
2280 /* This is only valid for single tasks */
2284 return do_tkill(0, pid, sig);
2288 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2292 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2295 /* Not even root can pretend to send signals from the kernel.
2296 Nor can they impersonate a kill(), which adds source info. */
2297 if (info.si_code >= 0)
2299 info.si_signo = sig;
2301 /* POSIX.1b doesn't mention process groups. */
2302 return kill_proc_info(sig, &info, pid);
2305 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2307 struct task_struct *t = current;
2308 struct k_sigaction *k;
2311 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2314 k = &t->sighand->action[sig-1];
2316 spin_lock_irq(¤t->sighand->siglock);
2321 sigdelsetmask(&act->sa.sa_mask,
2322 sigmask(SIGKILL) | sigmask(SIGSTOP));
2326 * "Setting a signal action to SIG_IGN for a signal that is
2327 * pending shall cause the pending signal to be discarded,
2328 * whether or not it is blocked."
2330 * "Setting a signal action to SIG_DFL for a signal that is
2331 * pending and whose default action is to ignore the signal
2332 * (for example, SIGCHLD), shall cause the pending signal to
2333 * be discarded, whether or not it is blocked"
2335 if (__sig_ignored(t, sig)) {
2337 sigaddset(&mask, sig);
2338 rm_from_queue_full(&mask, &t->signal->shared_pending);
2340 rm_from_queue_full(&mask, &t->pending);
2342 } while (t != current);
2346 spin_unlock_irq(¤t->sighand->siglock);
2351 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2357 oss.ss_sp = (void __user *) current->sas_ss_sp;
2358 oss.ss_size = current->sas_ss_size;
2359 oss.ss_flags = sas_ss_flags(sp);
2368 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2369 || __get_user(ss_sp, &uss->ss_sp)
2370 || __get_user(ss_flags, &uss->ss_flags)
2371 || __get_user(ss_size, &uss->ss_size))
2375 if (on_sig_stack(sp))
2381 * Note - this code used to test ss_flags incorrectly
2382 * old code may have been written using ss_flags==0
2383 * to mean ss_flags==SS_ONSTACK (as this was the only
2384 * way that worked) - this fix preserves that older
2387 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2390 if (ss_flags == SS_DISABLE) {
2395 if (ss_size < MINSIGSTKSZ)
2399 current->sas_ss_sp = (unsigned long) ss_sp;
2400 current->sas_ss_size = ss_size;
2405 if (copy_to_user(uoss, &oss, sizeof(oss)))
2414 #ifdef __ARCH_WANT_SYS_SIGPENDING
2417 sys_sigpending(old_sigset_t __user *set)
2419 return do_sigpending(set, sizeof(*set));
2424 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2425 /* Some platforms have their own version with special arguments others
2426 support only sys_rt_sigprocmask. */
2429 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2432 old_sigset_t old_set, new_set;
2436 if (copy_from_user(&new_set, set, sizeof(*set)))
2438 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2440 spin_lock_irq(¤t->sighand->siglock);
2441 old_set = current->blocked.sig[0];
2449 sigaddsetmask(¤t->blocked, new_set);
2452 sigdelsetmask(¤t->blocked, new_set);
2455 current->blocked.sig[0] = new_set;
2459 recalc_sigpending();
2460 spin_unlock_irq(¤t->sighand->siglock);
2466 old_set = current->blocked.sig[0];
2469 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2476 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2478 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2480 sys_rt_sigaction(int sig,
2481 const struct sigaction __user *act,
2482 struct sigaction __user *oact,
2485 struct k_sigaction new_sa, old_sa;
2488 /* XXX: Don't preclude handling different sized sigset_t's. */
2489 if (sigsetsize != sizeof(sigset_t))
2493 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2497 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2500 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2506 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2508 #ifdef __ARCH_WANT_SYS_SGETMASK
2511 * For backwards compatibility. Functionality superseded by sigprocmask.
2517 return current->blocked.sig[0];
2521 sys_ssetmask(int newmask)
2525 spin_lock_irq(¤t->sighand->siglock);
2526 old = current->blocked.sig[0];
2528 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2530 recalc_sigpending();
2531 spin_unlock_irq(¤t->sighand->siglock);
2535 #endif /* __ARCH_WANT_SGETMASK */
2537 #ifdef __ARCH_WANT_SYS_SIGNAL
2539 * For backwards compatibility. Functionality superseded by sigaction.
2541 asmlinkage unsigned long
2542 sys_signal(int sig, __sighandler_t handler)
2544 struct k_sigaction new_sa, old_sa;
2547 new_sa.sa.sa_handler = handler;
2548 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2549 sigemptyset(&new_sa.sa.sa_mask);
2551 ret = do_sigaction(sig, &new_sa, &old_sa);
2553 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2555 #endif /* __ARCH_WANT_SYS_SIGNAL */
2557 #ifdef __ARCH_WANT_SYS_PAUSE
2562 current->state = TASK_INTERRUPTIBLE;
2564 return -ERESTARTNOHAND;
2569 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2570 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2574 /* XXX: Don't preclude handling different sized sigset_t's. */
2575 if (sigsetsize != sizeof(sigset_t))
2578 if (copy_from_user(&newset, unewset, sizeof(newset)))
2580 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2582 spin_lock_irq(¤t->sighand->siglock);
2583 current->saved_sigmask = current->blocked;
2584 current->blocked = newset;
2585 recalc_sigpending();
2586 spin_unlock_irq(¤t->sighand->siglock);
2588 current->state = TASK_INTERRUPTIBLE;
2590 set_thread_flag(TIF_RESTORE_SIGMASK);
2591 return -ERESTARTNOHAND;
2593 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2595 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2600 void __init signals_init(void)
2602 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);