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;
656 * Test if P wants to take SIG. After we've checked all threads with this,
657 * it's equivalent to finding no threads not blocking SIG. Any threads not
658 * blocking SIG were ruled out because they are not running and already
659 * have pending signals. Such threads will dequeue from the shared queue
660 * as soon as they're available, so putting the signal on the shared queue
661 * will be equivalent to sending it to one such thread.
663 static inline int wants_signal(int sig, struct task_struct *p)
665 if (sigismember(&p->blocked, sig))
667 if (p->flags & PF_EXITING)
671 if (task_is_stopped_or_traced(p))
673 return task_curr(p) || !signal_pending(p);
676 static void complete_signal(int sig, struct task_struct *p, int group)
678 struct signal_struct *signal = p->signal;
679 struct task_struct *t;
682 * Now find a thread we can wake up to take the signal off the queue.
684 * If the main thread wants the signal, it gets first crack.
685 * Probably the least surprising to the average bear.
687 if (wants_signal(sig, p))
689 else if (!group || thread_group_empty(p))
691 * There is just one thread and it does not need to be woken.
692 * It will dequeue unblocked signals before it runs again.
697 * Otherwise try to find a suitable thread.
699 t = signal->curr_target;
700 while (!wants_signal(sig, t)) {
702 if (t == signal->curr_target)
704 * No thread needs to be woken.
705 * Any eligible threads will see
706 * the signal in the queue soon.
710 signal->curr_target = t;
714 * Found a killable thread. If the signal will be fatal,
715 * then start taking the whole group down immediately.
717 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
718 !sigismember(&t->real_blocked, sig) &&
719 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
721 * This signal will be fatal to the whole group.
723 if (!sig_kernel_coredump(sig)) {
725 * Start a group exit and wake everybody up.
726 * This way we don't have other threads
727 * running and doing things after a slower
728 * thread has the fatal signal pending.
730 signal->flags = SIGNAL_GROUP_EXIT;
731 signal->group_exit_code = sig;
732 signal->group_stop_count = 0;
735 sigaddset(&t->pending.signal, SIGKILL);
736 signal_wake_up(t, 1);
737 } while_each_thread(p, t);
743 * The signal is already in the shared-pending queue.
744 * Tell the chosen thread to wake up and dequeue it.
746 signal_wake_up(t, sig == SIGKILL);
750 static inline int legacy_queue(struct sigpending *signals, int sig)
752 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
755 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
758 struct sigpending *pending;
761 assert_spin_locked(&t->sighand->siglock);
762 handle_stop_signal(sig, t);
764 pending = group ? &t->signal->shared_pending : &t->pending;
766 * Short-circuit ignored signals and support queuing
767 * exactly one non-rt signal, so that we can get more
768 * detailed information about the cause of the signal.
770 if (sig_ignored(t, sig) || legacy_queue(pending, sig))
774 * Deliver the signal to listening signalfds. This must be called
775 * with the sighand lock held.
777 signalfd_notify(t, sig);
780 * fast-pathed signals for kernel-internal things like SIGSTOP
783 if (info == SEND_SIG_FORCED)
786 /* Real-time signals must be queued if sent by sigqueue, or
787 some other real-time mechanism. It is implementation
788 defined whether kill() does so. We attempt to do so, on
789 the principle of least surprise, but since kill is not
790 allowed to fail with EAGAIN when low on memory we just
791 make sure at least one signal gets delivered and don't
792 pass on the info struct. */
794 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
795 (is_si_special(info) ||
796 info->si_code >= 0)));
798 list_add_tail(&q->list, &pending->list);
799 switch ((unsigned long) info) {
800 case (unsigned long) SEND_SIG_NOINFO:
801 q->info.si_signo = sig;
802 q->info.si_errno = 0;
803 q->info.si_code = SI_USER;
804 q->info.si_pid = task_pid_vnr(current);
805 q->info.si_uid = current->uid;
807 case (unsigned long) SEND_SIG_PRIV:
808 q->info.si_signo = sig;
809 q->info.si_errno = 0;
810 q->info.si_code = SI_KERNEL;
815 copy_siginfo(&q->info, info);
818 } else if (!is_si_special(info)) {
819 if (sig >= SIGRTMIN && info->si_code != SI_USER)
821 * Queue overflow, abort. We may abort if the signal was rt
822 * and sent by user using something other than kill().
828 sigaddset(&pending->signal, sig);
829 complete_signal(sig, t, group);
833 int print_fatal_signals;
835 static void print_fatal_signal(struct pt_regs *regs, int signr)
837 printk("%s/%d: potentially unexpected fatal signal %d.\n",
838 current->comm, task_pid_nr(current), signr);
840 #if defined(__i386__) && !defined(__arch_um__)
841 printk("code at %08lx: ", regs->ip);
844 for (i = 0; i < 16; i++) {
847 __get_user(insn, (unsigned char *)(regs->ip + i));
848 printk("%02x ", insn);
856 static int __init setup_print_fatal_signals(char *str)
858 get_option (&str, &print_fatal_signals);
863 __setup("print-fatal-signals=", setup_print_fatal_signals);
866 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
868 return send_signal(sig, info, p, 1);
872 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
874 return send_signal(sig, info, t, 0);
878 * Force a signal that the process can't ignore: if necessary
879 * we unblock the signal and change any SIG_IGN to SIG_DFL.
881 * Note: If we unblock the signal, we always reset it to SIG_DFL,
882 * since we do not want to have a signal handler that was blocked
883 * be invoked when user space had explicitly blocked it.
885 * We don't want to have recursive SIGSEGV's etc, for example.
888 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
890 unsigned long int flags;
891 int ret, blocked, ignored;
892 struct k_sigaction *action;
894 spin_lock_irqsave(&t->sighand->siglock, flags);
895 action = &t->sighand->action[sig-1];
896 ignored = action->sa.sa_handler == SIG_IGN;
897 blocked = sigismember(&t->blocked, sig);
898 if (blocked || ignored) {
899 action->sa.sa_handler = SIG_DFL;
901 sigdelset(&t->blocked, sig);
902 recalc_sigpending_and_wake(t);
905 ret = specific_send_sig_info(sig, info, t);
906 spin_unlock_irqrestore(&t->sighand->siglock, flags);
912 force_sig_specific(int sig, struct task_struct *t)
914 force_sig_info(sig, SEND_SIG_FORCED, t);
918 * Nuke all other threads in the group.
920 void zap_other_threads(struct task_struct *p)
922 struct task_struct *t;
924 p->signal->group_stop_count = 0;
926 for (t = next_thread(p); t != p; t = next_thread(t)) {
928 * Don't bother with already dead threads
933 /* SIGKILL will be handled before any pending SIGSTOP */
934 sigaddset(&t->pending.signal, SIGKILL);
935 signal_wake_up(t, 1);
939 int __fatal_signal_pending(struct task_struct *tsk)
941 return sigismember(&tsk->pending.signal, SIGKILL);
943 EXPORT_SYMBOL(__fatal_signal_pending);
945 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
947 struct sighand_struct *sighand;
951 sighand = rcu_dereference(tsk->sighand);
952 if (unlikely(sighand == NULL))
955 spin_lock_irqsave(&sighand->siglock, *flags);
956 if (likely(sighand == tsk->sighand))
958 spin_unlock_irqrestore(&sighand->siglock, *flags);
965 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
970 ret = check_kill_permission(sig, info, p);
974 if (lock_task_sighand(p, &flags)) {
975 ret = __group_send_sig_info(sig, info, p);
976 unlock_task_sighand(p, &flags);
984 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
985 * control characters do (^C, ^Z etc)
988 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
990 struct task_struct *p = NULL;
995 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
996 int err = group_send_sig_info(sig, info, p);
999 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1000 return success ? 0 : retval;
1003 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1006 struct task_struct *p;
1010 p = pid_task(pid, PIDTYPE_PID);
1012 error = group_send_sig_info(sig, info, p);
1013 if (unlikely(error == -ESRCH))
1015 * The task was unhashed in between, try again.
1016 * If it is dead, pid_task() will return NULL,
1017 * if we race with de_thread() it will find the
1028 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1032 error = kill_pid_info(sig, info, find_vpid(pid));
1037 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1038 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1039 uid_t uid, uid_t euid, u32 secid)
1042 struct task_struct *p;
1044 if (!valid_signal(sig))
1047 read_lock(&tasklist_lock);
1048 p = pid_task(pid, PIDTYPE_PID);
1053 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1054 && (euid != p->suid) && (euid != p->uid)
1055 && (uid != p->suid) && (uid != p->uid)) {
1059 ret = security_task_kill(p, info, sig, secid);
1062 if (sig && p->sighand) {
1063 unsigned long flags;
1064 spin_lock_irqsave(&p->sighand->siglock, flags);
1065 ret = __group_send_sig_info(sig, info, p);
1066 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1069 read_unlock(&tasklist_lock);
1072 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1075 * kill_something_info() interprets pid in interesting ways just like kill(2).
1077 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1078 * is probably wrong. Should make it like BSD or SYSV.
1081 static int kill_something_info(int sig, struct siginfo *info, int pid)
1087 ret = kill_pid_info(sig, info, find_vpid(pid));
1092 read_lock(&tasklist_lock);
1094 ret = __kill_pgrp_info(sig, info,
1095 pid ? find_vpid(-pid) : task_pgrp(current));
1097 int retval = 0, count = 0;
1098 struct task_struct * p;
1100 for_each_process(p) {
1101 if (p->pid > 1 && !same_thread_group(p, current)) {
1102 int err = group_send_sig_info(sig, info, p);
1108 ret = count ? retval : -ESRCH;
1110 read_unlock(&tasklist_lock);
1116 * These are for backward compatibility with the rest of the kernel source.
1120 * The caller must ensure the task can't exit.
1123 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1126 unsigned long flags;
1129 * Make sure legacy kernel users don't send in bad values
1130 * (normal paths check this in check_kill_permission).
1132 if (!valid_signal(sig))
1135 spin_lock_irqsave(&p->sighand->siglock, flags);
1136 ret = specific_send_sig_info(sig, info, p);
1137 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1141 #define __si_special(priv) \
1142 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1145 send_sig(int sig, struct task_struct *p, int priv)
1147 return send_sig_info(sig, __si_special(priv), p);
1151 force_sig(int sig, struct task_struct *p)
1153 force_sig_info(sig, SEND_SIG_PRIV, p);
1157 * When things go south during signal handling, we
1158 * will force a SIGSEGV. And if the signal that caused
1159 * the problem was already a SIGSEGV, we'll want to
1160 * make sure we don't even try to deliver the signal..
1163 force_sigsegv(int sig, struct task_struct *p)
1165 if (sig == SIGSEGV) {
1166 unsigned long flags;
1167 spin_lock_irqsave(&p->sighand->siglock, flags);
1168 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1169 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1171 force_sig(SIGSEGV, p);
1175 int kill_pgrp(struct pid *pid, int sig, int priv)
1179 read_lock(&tasklist_lock);
1180 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1181 read_unlock(&tasklist_lock);
1185 EXPORT_SYMBOL(kill_pgrp);
1187 int kill_pid(struct pid *pid, int sig, int priv)
1189 return kill_pid_info(sig, __si_special(priv), pid);
1191 EXPORT_SYMBOL(kill_pid);
1194 kill_proc(pid_t pid, int sig, int priv)
1199 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1205 * These functions support sending signals using preallocated sigqueue
1206 * structures. This is needed "because realtime applications cannot
1207 * afford to lose notifications of asynchronous events, like timer
1208 * expirations or I/O completions". In the case of Posix Timers
1209 * we allocate the sigqueue structure from the timer_create. If this
1210 * allocation fails we are able to report the failure to the application
1211 * with an EAGAIN error.
1214 struct sigqueue *sigqueue_alloc(void)
1218 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1219 q->flags |= SIGQUEUE_PREALLOC;
1223 void sigqueue_free(struct sigqueue *q)
1225 unsigned long flags;
1226 spinlock_t *lock = ¤t->sighand->siglock;
1228 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1230 * If the signal is still pending remove it from the
1231 * pending queue. We must hold ->siglock while testing
1232 * q->list to serialize with collect_signal().
1234 spin_lock_irqsave(lock, flags);
1235 if (!list_empty(&q->list))
1236 list_del_init(&q->list);
1237 spin_unlock_irqrestore(lock, flags);
1239 q->flags &= ~SIGQUEUE_PREALLOC;
1243 static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
1246 struct sigpending *pending;
1248 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1249 handle_stop_signal(sig, t);
1251 if (unlikely(!list_empty(&q->list))) {
1253 * If an SI_TIMER entry is already queue just increment
1254 * the overrun count.
1257 BUG_ON(q->info.si_code != SI_TIMER);
1258 q->info.si_overrun++;
1262 if (sig_ignored(t, sig))
1265 signalfd_notify(t, sig);
1266 pending = group ? &t->signal->shared_pending : &t->pending;
1267 list_add_tail(&q->list, &pending->list);
1268 sigaddset(&pending->signal, sig);
1269 complete_signal(sig, t, group);
1274 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1276 unsigned long flags;
1280 * The rcu based delayed sighand destroy makes it possible to
1281 * run this without tasklist lock held. The task struct itself
1282 * cannot go away as create_timer did get_task_struct().
1284 * We return -1, when the task is marked exiting, so
1285 * posix_timer_event can redirect it to the group leader
1287 if (!likely(lock_task_sighand(p, &flags)))
1290 ret = do_send_sigqueue(sig, q, p, 0);
1292 unlock_task_sighand(p, &flags);
1298 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1300 unsigned long flags;
1303 /* Since it_lock is held, p->sighand cannot be NULL. */
1304 spin_lock_irqsave(&p->sighand->siglock, flags);
1306 ret = do_send_sigqueue(sig, q, p, 1);
1308 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1314 * Wake up any threads in the parent blocked in wait* syscalls.
1316 static inline void __wake_up_parent(struct task_struct *p,
1317 struct task_struct *parent)
1319 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1323 * Let a parent know about the death of a child.
1324 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1327 void do_notify_parent(struct task_struct *tsk, int sig)
1329 struct siginfo info;
1330 unsigned long flags;
1331 struct sighand_struct *psig;
1335 /* do_notify_parent_cldstop should have been called instead. */
1336 BUG_ON(task_is_stopped_or_traced(tsk));
1338 BUG_ON(!tsk->ptrace &&
1339 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1341 info.si_signo = sig;
1344 * we are under tasklist_lock here so our parent is tied to
1345 * us and cannot exit and release its namespace.
1347 * the only it can is to switch its nsproxy with sys_unshare,
1348 * bu uncharing pid namespaces is not allowed, so we'll always
1349 * see relevant namespace
1351 * write_lock() currently calls preempt_disable() which is the
1352 * same as rcu_read_lock(), but according to Oleg, this is not
1353 * correct to rely on this
1356 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1359 info.si_uid = tsk->uid;
1361 /* FIXME: find out whether or not this is supposed to be c*time. */
1362 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1363 tsk->signal->utime));
1364 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1365 tsk->signal->stime));
1367 info.si_status = tsk->exit_code & 0x7f;
1368 if (tsk->exit_code & 0x80)
1369 info.si_code = CLD_DUMPED;
1370 else if (tsk->exit_code & 0x7f)
1371 info.si_code = CLD_KILLED;
1373 info.si_code = CLD_EXITED;
1374 info.si_status = tsk->exit_code >> 8;
1377 psig = tsk->parent->sighand;
1378 spin_lock_irqsave(&psig->siglock, flags);
1379 if (!tsk->ptrace && sig == SIGCHLD &&
1380 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1381 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1383 * We are exiting and our parent doesn't care. POSIX.1
1384 * defines special semantics for setting SIGCHLD to SIG_IGN
1385 * or setting the SA_NOCLDWAIT flag: we should be reaped
1386 * automatically and not left for our parent's wait4 call.
1387 * Rather than having the parent do it as a magic kind of
1388 * signal handler, we just set this to tell do_exit that we
1389 * can be cleaned up without becoming a zombie. Note that
1390 * we still call __wake_up_parent in this case, because a
1391 * blocked sys_wait4 might now return -ECHILD.
1393 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1394 * is implementation-defined: we do (if you don't want
1395 * it, just use SIG_IGN instead).
1397 tsk->exit_signal = -1;
1398 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1401 if (valid_signal(sig) && sig > 0)
1402 __group_send_sig_info(sig, &info, tsk->parent);
1403 __wake_up_parent(tsk, tsk->parent);
1404 spin_unlock_irqrestore(&psig->siglock, flags);
1407 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1409 struct siginfo info;
1410 unsigned long flags;
1411 struct task_struct *parent;
1412 struct sighand_struct *sighand;
1414 if (tsk->ptrace & PT_PTRACED)
1415 parent = tsk->parent;
1417 tsk = tsk->group_leader;
1418 parent = tsk->real_parent;
1421 info.si_signo = SIGCHLD;
1424 * see comment in do_notify_parent() abot the following 3 lines
1427 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1430 info.si_uid = tsk->uid;
1432 /* FIXME: find out whether or not this is supposed to be c*time. */
1433 info.si_utime = cputime_to_jiffies(tsk->utime);
1434 info.si_stime = cputime_to_jiffies(tsk->stime);
1439 info.si_status = SIGCONT;
1442 info.si_status = tsk->signal->group_exit_code & 0x7f;
1445 info.si_status = tsk->exit_code & 0x7f;
1451 sighand = parent->sighand;
1452 spin_lock_irqsave(&sighand->siglock, flags);
1453 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1454 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1455 __group_send_sig_info(SIGCHLD, &info, parent);
1457 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1459 __wake_up_parent(tsk, parent);
1460 spin_unlock_irqrestore(&sighand->siglock, flags);
1463 static inline int may_ptrace_stop(void)
1465 if (!likely(current->ptrace & PT_PTRACED))
1468 * Are we in the middle of do_coredump?
1469 * If so and our tracer is also part of the coredump stopping
1470 * is a deadlock situation, and pointless because our tracer
1471 * is dead so don't allow us to stop.
1472 * If SIGKILL was already sent before the caller unlocked
1473 * ->siglock we must see ->core_waiters != 0. Otherwise it
1474 * is safe to enter schedule().
1476 if (unlikely(current->mm->core_waiters) &&
1477 unlikely(current->mm == current->parent->mm))
1484 * Return nonzero if there is a SIGKILL that should be waking us up.
1485 * Called with the siglock held.
1487 static int sigkill_pending(struct task_struct *tsk)
1489 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1490 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1491 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1495 * This must be called with current->sighand->siglock held.
1497 * This should be the path for all ptrace stops.
1498 * We always set current->last_siginfo while stopped here.
1499 * That makes it a way to test a stopped process for
1500 * being ptrace-stopped vs being job-control-stopped.
1502 * If we actually decide not to stop at all because the tracer
1503 * is gone, we keep current->exit_code unless clear_code.
1505 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1509 if (arch_ptrace_stop_needed(exit_code, info)) {
1511 * The arch code has something special to do before a
1512 * ptrace stop. This is allowed to block, e.g. for faults
1513 * on user stack pages. We can't keep the siglock while
1514 * calling arch_ptrace_stop, so we must release it now.
1515 * To preserve proper semantics, we must do this before
1516 * any signal bookkeeping like checking group_stop_count.
1517 * Meanwhile, a SIGKILL could come in before we retake the
1518 * siglock. That must prevent us from sleeping in TASK_TRACED.
1519 * So after regaining the lock, we must check for SIGKILL.
1521 spin_unlock_irq(¤t->sighand->siglock);
1522 arch_ptrace_stop(exit_code, info);
1523 spin_lock_irq(¤t->sighand->siglock);
1524 killed = sigkill_pending(current);
1528 * If there is a group stop in progress,
1529 * we must participate in the bookkeeping.
1531 if (current->signal->group_stop_count > 0)
1532 --current->signal->group_stop_count;
1534 current->last_siginfo = info;
1535 current->exit_code = exit_code;
1537 /* Let the debugger run. */
1538 __set_current_state(TASK_TRACED);
1539 spin_unlock_irq(¤t->sighand->siglock);
1540 read_lock(&tasklist_lock);
1541 if (!unlikely(killed) && may_ptrace_stop()) {
1542 do_notify_parent_cldstop(current, CLD_TRAPPED);
1543 read_unlock(&tasklist_lock);
1547 * By the time we got the lock, our tracer went away.
1548 * Don't drop the lock yet, another tracer may come.
1550 __set_current_state(TASK_RUNNING);
1552 current->exit_code = 0;
1553 read_unlock(&tasklist_lock);
1557 * While in TASK_TRACED, we were considered "frozen enough".
1558 * Now that we woke up, it's crucial if we're supposed to be
1559 * frozen that we freeze now before running anything substantial.
1564 * We are back. Now reacquire the siglock before touching
1565 * last_siginfo, so that we are sure to have synchronized with
1566 * any signal-sending on another CPU that wants to examine it.
1568 spin_lock_irq(¤t->sighand->siglock);
1569 current->last_siginfo = NULL;
1572 * Queued signals ignored us while we were stopped for tracing.
1573 * So check for any that we should take before resuming user mode.
1574 * This sets TIF_SIGPENDING, but never clears it.
1576 recalc_sigpending_tsk(current);
1579 void ptrace_notify(int exit_code)
1583 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1585 memset(&info, 0, sizeof info);
1586 info.si_signo = SIGTRAP;
1587 info.si_code = exit_code;
1588 info.si_pid = task_pid_vnr(current);
1589 info.si_uid = current->uid;
1591 /* Let the debugger run. */
1592 spin_lock_irq(¤t->sighand->siglock);
1593 ptrace_stop(exit_code, 1, &info);
1594 spin_unlock_irq(¤t->sighand->siglock);
1598 finish_stop(int stop_count)
1601 * If there are no other threads in the group, or if there is
1602 * a group stop in progress and we are the last to stop,
1603 * report to the parent. When ptraced, every thread reports itself.
1605 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1606 read_lock(&tasklist_lock);
1607 do_notify_parent_cldstop(current, CLD_STOPPED);
1608 read_unlock(&tasklist_lock);
1613 } while (try_to_freeze());
1615 * Now we don't run again until continued.
1617 current->exit_code = 0;
1621 * This performs the stopping for SIGSTOP and other stop signals.
1622 * We have to stop all threads in the thread group.
1623 * Returns nonzero if we've actually stopped and released the siglock.
1624 * Returns zero if we didn't stop and still hold the siglock.
1626 static int do_signal_stop(int signr)
1628 struct signal_struct *sig = current->signal;
1631 if (sig->group_stop_count > 0) {
1633 * There is a group stop in progress. We don't need to
1634 * start another one.
1636 stop_count = --sig->group_stop_count;
1638 struct task_struct *t;
1640 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1641 unlikely(signal_group_exit(sig)))
1644 * There is no group stop already in progress.
1645 * We must initiate one now.
1647 sig->group_exit_code = signr;
1650 for (t = next_thread(current); t != current; t = next_thread(t))
1652 * Setting state to TASK_STOPPED for a group
1653 * stop is always done with the siglock held,
1654 * so this check has no races.
1656 if (!(t->flags & PF_EXITING) &&
1657 !task_is_stopped_or_traced(t)) {
1659 signal_wake_up(t, 0);
1661 sig->group_stop_count = stop_count;
1664 if (stop_count == 0)
1665 sig->flags = SIGNAL_STOP_STOPPED;
1666 current->exit_code = sig->group_exit_code;
1667 __set_current_state(TASK_STOPPED);
1669 spin_unlock_irq(¤t->sighand->siglock);
1670 finish_stop(stop_count);
1674 static int ptrace_signal(int signr, siginfo_t *info,
1675 struct pt_regs *regs, void *cookie)
1677 if (!(current->ptrace & PT_PTRACED))
1680 ptrace_signal_deliver(regs, cookie);
1682 /* Let the debugger run. */
1683 ptrace_stop(signr, 0, info);
1685 /* We're back. Did the debugger cancel the sig? */
1686 signr = current->exit_code;
1690 current->exit_code = 0;
1692 /* Update the siginfo structure if the signal has
1693 changed. If the debugger wanted something
1694 specific in the siginfo structure then it should
1695 have updated *info via PTRACE_SETSIGINFO. */
1696 if (signr != info->si_signo) {
1697 info->si_signo = signr;
1699 info->si_code = SI_USER;
1700 info->si_pid = task_pid_vnr(current->parent);
1701 info->si_uid = current->parent->uid;
1704 /* If the (new) signal is now blocked, requeue it. */
1705 if (sigismember(¤t->blocked, signr)) {
1706 specific_send_sig_info(signr, info, current);
1713 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1714 struct pt_regs *regs, void *cookie)
1716 struct sighand_struct *sighand = current->sighand;
1717 struct signal_struct *signal = current->signal;
1722 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1723 * While in TASK_STOPPED, we were considered "frozen enough".
1724 * Now that we woke up, it's crucial if we're supposed to be
1725 * frozen that we freeze now before running anything substantial.
1729 spin_lock_irq(&sighand->siglock);
1731 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1732 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1733 ? CLD_CONTINUED : CLD_STOPPED;
1734 signal->flags &= ~SIGNAL_CLD_MASK;
1735 spin_unlock_irq(&sighand->siglock);
1737 read_lock(&tasklist_lock);
1738 do_notify_parent_cldstop(current->group_leader, why);
1739 read_unlock(&tasklist_lock);
1744 struct k_sigaction *ka;
1746 if (unlikely(signal->group_stop_count > 0) &&
1750 signr = dequeue_signal(current, ¤t->blocked, info);
1752 break; /* will return 0 */
1754 if (signr != SIGKILL) {
1755 signr = ptrace_signal(signr, info, regs, cookie);
1760 ka = &sighand->action[signr-1];
1761 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1763 if (ka->sa.sa_handler != SIG_DFL) {
1764 /* Run the handler. */
1767 if (ka->sa.sa_flags & SA_ONESHOT)
1768 ka->sa.sa_handler = SIG_DFL;
1770 break; /* will return non-zero "signr" value */
1774 * Now we are doing the default action for this signal.
1776 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1780 * Global init gets no signals it doesn't want.
1782 if (is_global_init(current))
1785 if (sig_kernel_stop(signr)) {
1787 * The default action is to stop all threads in
1788 * the thread group. The job control signals
1789 * do nothing in an orphaned pgrp, but SIGSTOP
1790 * always works. Note that siglock needs to be
1791 * dropped during the call to is_orphaned_pgrp()
1792 * because of lock ordering with tasklist_lock.
1793 * This allows an intervening SIGCONT to be posted.
1794 * We need to check for that and bail out if necessary.
1796 if (signr != SIGSTOP) {
1797 spin_unlock_irq(&sighand->siglock);
1799 /* signals can be posted during this window */
1801 if (is_current_pgrp_orphaned())
1804 spin_lock_irq(&sighand->siglock);
1807 if (likely(do_signal_stop(signr))) {
1808 /* It released the siglock. */
1813 * We didn't actually stop, due to a race
1814 * with SIGCONT or something like that.
1819 spin_unlock_irq(&sighand->siglock);
1822 * Anything else is fatal, maybe with a core dump.
1824 current->flags |= PF_SIGNALED;
1825 if ((signr != SIGKILL) && print_fatal_signals)
1826 print_fatal_signal(regs, signr);
1827 if (sig_kernel_coredump(signr)) {
1829 * If it was able to dump core, this kills all
1830 * other threads in the group and synchronizes with
1831 * their demise. If we lost the race with another
1832 * thread getting here, it set group_exit_code
1833 * first and our do_group_exit call below will use
1834 * that value and ignore the one we pass it.
1836 do_coredump((long)signr, signr, regs);
1840 * Death signals, no core dump.
1842 do_group_exit(signr);
1845 spin_unlock_irq(&sighand->siglock);
1849 void exit_signals(struct task_struct *tsk)
1852 struct task_struct *t;
1854 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1855 tsk->flags |= PF_EXITING;
1859 spin_lock_irq(&tsk->sighand->siglock);
1861 * From now this task is not visible for group-wide signals,
1862 * see wants_signal(), do_signal_stop().
1864 tsk->flags |= PF_EXITING;
1865 if (!signal_pending(tsk))
1868 /* It could be that __group_complete_signal() choose us to
1869 * notify about group-wide signal. Another thread should be
1870 * woken now to take the signal since we will not.
1872 for (t = tsk; (t = next_thread(t)) != tsk; )
1873 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1874 recalc_sigpending_and_wake(t);
1876 if (unlikely(tsk->signal->group_stop_count) &&
1877 !--tsk->signal->group_stop_count) {
1878 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1882 spin_unlock_irq(&tsk->sighand->siglock);
1884 if (unlikely(group_stop)) {
1885 read_lock(&tasklist_lock);
1886 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1887 read_unlock(&tasklist_lock);
1891 EXPORT_SYMBOL(recalc_sigpending);
1892 EXPORT_SYMBOL_GPL(dequeue_signal);
1893 EXPORT_SYMBOL(flush_signals);
1894 EXPORT_SYMBOL(force_sig);
1895 EXPORT_SYMBOL(kill_proc);
1896 EXPORT_SYMBOL(ptrace_notify);
1897 EXPORT_SYMBOL(send_sig);
1898 EXPORT_SYMBOL(send_sig_info);
1899 EXPORT_SYMBOL(sigprocmask);
1900 EXPORT_SYMBOL(block_all_signals);
1901 EXPORT_SYMBOL(unblock_all_signals);
1905 * System call entry points.
1908 asmlinkage long sys_restart_syscall(void)
1910 struct restart_block *restart = ¤t_thread_info()->restart_block;
1911 return restart->fn(restart);
1914 long do_no_restart_syscall(struct restart_block *param)
1920 * We don't need to get the kernel lock - this is all local to this
1921 * particular thread.. (and that's good, because this is _heavily_
1922 * used by various programs)
1926 * This is also useful for kernel threads that want to temporarily
1927 * (or permanently) block certain signals.
1929 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1930 * interface happily blocks "unblockable" signals like SIGKILL
1933 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1937 spin_lock_irq(¤t->sighand->siglock);
1939 *oldset = current->blocked;
1944 sigorsets(¤t->blocked, ¤t->blocked, set);
1947 signandsets(¤t->blocked, ¤t->blocked, set);
1950 current->blocked = *set;
1955 recalc_sigpending();
1956 spin_unlock_irq(¤t->sighand->siglock);
1962 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1964 int error = -EINVAL;
1965 sigset_t old_set, new_set;
1967 /* XXX: Don't preclude handling different sized sigset_t's. */
1968 if (sigsetsize != sizeof(sigset_t))
1973 if (copy_from_user(&new_set, set, sizeof(*set)))
1975 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1977 error = sigprocmask(how, &new_set, &old_set);
1983 spin_lock_irq(¤t->sighand->siglock);
1984 old_set = current->blocked;
1985 spin_unlock_irq(¤t->sighand->siglock);
1989 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1997 long do_sigpending(void __user *set, unsigned long sigsetsize)
1999 long error = -EINVAL;
2002 if (sigsetsize > sizeof(sigset_t))
2005 spin_lock_irq(¤t->sighand->siglock);
2006 sigorsets(&pending, ¤t->pending.signal,
2007 ¤t->signal->shared_pending.signal);
2008 spin_unlock_irq(¤t->sighand->siglock);
2010 /* Outside the lock because only this thread touches it. */
2011 sigandsets(&pending, ¤t->blocked, &pending);
2014 if (!copy_to_user(set, &pending, sigsetsize))
2022 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2024 return do_sigpending(set, sigsetsize);
2027 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2029 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2033 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2035 if (from->si_code < 0)
2036 return __copy_to_user(to, from, sizeof(siginfo_t))
2039 * If you change siginfo_t structure, please be sure
2040 * this code is fixed accordingly.
2041 * Please remember to update the signalfd_copyinfo() function
2042 * inside fs/signalfd.c too, in case siginfo_t changes.
2043 * It should never copy any pad contained in the structure
2044 * to avoid security leaks, but must copy the generic
2045 * 3 ints plus the relevant union member.
2047 err = __put_user(from->si_signo, &to->si_signo);
2048 err |= __put_user(from->si_errno, &to->si_errno);
2049 err |= __put_user((short)from->si_code, &to->si_code);
2050 switch (from->si_code & __SI_MASK) {
2052 err |= __put_user(from->si_pid, &to->si_pid);
2053 err |= __put_user(from->si_uid, &to->si_uid);
2056 err |= __put_user(from->si_tid, &to->si_tid);
2057 err |= __put_user(from->si_overrun, &to->si_overrun);
2058 err |= __put_user(from->si_ptr, &to->si_ptr);
2061 err |= __put_user(from->si_band, &to->si_band);
2062 err |= __put_user(from->si_fd, &to->si_fd);
2065 err |= __put_user(from->si_addr, &to->si_addr);
2066 #ifdef __ARCH_SI_TRAPNO
2067 err |= __put_user(from->si_trapno, &to->si_trapno);
2071 err |= __put_user(from->si_pid, &to->si_pid);
2072 err |= __put_user(from->si_uid, &to->si_uid);
2073 err |= __put_user(from->si_status, &to->si_status);
2074 err |= __put_user(from->si_utime, &to->si_utime);
2075 err |= __put_user(from->si_stime, &to->si_stime);
2077 case __SI_RT: /* This is not generated by the kernel as of now. */
2078 case __SI_MESGQ: /* But this is */
2079 err |= __put_user(from->si_pid, &to->si_pid);
2080 err |= __put_user(from->si_uid, &to->si_uid);
2081 err |= __put_user(from->si_ptr, &to->si_ptr);
2083 default: /* this is just in case for now ... */
2084 err |= __put_user(from->si_pid, &to->si_pid);
2085 err |= __put_user(from->si_uid, &to->si_uid);
2094 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2095 siginfo_t __user *uinfo,
2096 const struct timespec __user *uts,
2105 /* XXX: Don't preclude handling different sized sigset_t's. */
2106 if (sigsetsize != sizeof(sigset_t))
2109 if (copy_from_user(&these, uthese, sizeof(these)))
2113 * Invert the set of allowed signals to get those we
2116 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2120 if (copy_from_user(&ts, uts, sizeof(ts)))
2122 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2127 spin_lock_irq(¤t->sighand->siglock);
2128 sig = dequeue_signal(current, &these, &info);
2130 timeout = MAX_SCHEDULE_TIMEOUT;
2132 timeout = (timespec_to_jiffies(&ts)
2133 + (ts.tv_sec || ts.tv_nsec));
2136 /* None ready -- temporarily unblock those we're
2137 * interested while we are sleeping in so that we'll
2138 * be awakened when they arrive. */
2139 current->real_blocked = current->blocked;
2140 sigandsets(¤t->blocked, ¤t->blocked, &these);
2141 recalc_sigpending();
2142 spin_unlock_irq(¤t->sighand->siglock);
2144 timeout = schedule_timeout_interruptible(timeout);
2146 spin_lock_irq(¤t->sighand->siglock);
2147 sig = dequeue_signal(current, &these, &info);
2148 current->blocked = current->real_blocked;
2149 siginitset(¤t->real_blocked, 0);
2150 recalc_sigpending();
2153 spin_unlock_irq(¤t->sighand->siglock);
2158 if (copy_siginfo_to_user(uinfo, &info))
2171 sys_kill(int pid, int sig)
2173 struct siginfo info;
2175 info.si_signo = sig;
2177 info.si_code = SI_USER;
2178 info.si_pid = task_tgid_vnr(current);
2179 info.si_uid = current->uid;
2181 return kill_something_info(sig, &info, pid);
2184 static int do_tkill(int tgid, int pid, int sig)
2187 struct siginfo info;
2188 struct task_struct *p;
2189 unsigned long flags;
2192 info.si_signo = sig;
2194 info.si_code = SI_TKILL;
2195 info.si_pid = task_tgid_vnr(current);
2196 info.si_uid = current->uid;
2199 p = find_task_by_vpid(pid);
2200 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2201 error = check_kill_permission(sig, &info, p);
2203 * The null signal is a permissions and process existence
2204 * probe. No signal is actually delivered.
2206 * If lock_task_sighand() fails we pretend the task dies
2207 * after receiving the signal. The window is tiny, and the
2208 * signal is private anyway.
2210 if (!error && sig && lock_task_sighand(p, &flags)) {
2211 error = specific_send_sig_info(sig, &info, p);
2212 unlock_task_sighand(p, &flags);
2221 * sys_tgkill - send signal to one specific thread
2222 * @tgid: the thread group ID of the thread
2223 * @pid: the PID of the thread
2224 * @sig: signal to be sent
2226 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2227 * exists but it's not belonging to the target process anymore. This
2228 * method solves the problem of threads exiting and PIDs getting reused.
2230 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2232 /* This is only valid for single tasks */
2233 if (pid <= 0 || tgid <= 0)
2236 return do_tkill(tgid, pid, sig);
2240 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2243 sys_tkill(int pid, int sig)
2245 /* This is only valid for single tasks */
2249 return do_tkill(0, pid, sig);
2253 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2257 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2260 /* Not even root can pretend to send signals from the kernel.
2261 Nor can they impersonate a kill(), which adds source info. */
2262 if (info.si_code >= 0)
2264 info.si_signo = sig;
2266 /* POSIX.1b doesn't mention process groups. */
2267 return kill_proc_info(sig, &info, pid);
2270 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2272 struct task_struct *t = current;
2273 struct k_sigaction *k;
2276 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2279 k = &t->sighand->action[sig-1];
2281 spin_lock_irq(¤t->sighand->siglock);
2286 sigdelsetmask(&act->sa.sa_mask,
2287 sigmask(SIGKILL) | sigmask(SIGSTOP));
2291 * "Setting a signal action to SIG_IGN for a signal that is
2292 * pending shall cause the pending signal to be discarded,
2293 * whether or not it is blocked."
2295 * "Setting a signal action to SIG_DFL for a signal that is
2296 * pending and whose default action is to ignore the signal
2297 * (for example, SIGCHLD), shall cause the pending signal to
2298 * be discarded, whether or not it is blocked"
2300 if (__sig_ignored(t, sig)) {
2302 sigaddset(&mask, sig);
2303 rm_from_queue_full(&mask, &t->signal->shared_pending);
2305 rm_from_queue_full(&mask, &t->pending);
2307 } while (t != current);
2311 spin_unlock_irq(¤t->sighand->siglock);
2316 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2322 oss.ss_sp = (void __user *) current->sas_ss_sp;
2323 oss.ss_size = current->sas_ss_size;
2324 oss.ss_flags = sas_ss_flags(sp);
2333 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2334 || __get_user(ss_sp, &uss->ss_sp)
2335 || __get_user(ss_flags, &uss->ss_flags)
2336 || __get_user(ss_size, &uss->ss_size))
2340 if (on_sig_stack(sp))
2346 * Note - this code used to test ss_flags incorrectly
2347 * old code may have been written using ss_flags==0
2348 * to mean ss_flags==SS_ONSTACK (as this was the only
2349 * way that worked) - this fix preserves that older
2352 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2355 if (ss_flags == SS_DISABLE) {
2360 if (ss_size < MINSIGSTKSZ)
2364 current->sas_ss_sp = (unsigned long) ss_sp;
2365 current->sas_ss_size = ss_size;
2370 if (copy_to_user(uoss, &oss, sizeof(oss)))
2379 #ifdef __ARCH_WANT_SYS_SIGPENDING
2382 sys_sigpending(old_sigset_t __user *set)
2384 return do_sigpending(set, sizeof(*set));
2389 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2390 /* Some platforms have their own version with special arguments others
2391 support only sys_rt_sigprocmask. */
2394 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2397 old_sigset_t old_set, new_set;
2401 if (copy_from_user(&new_set, set, sizeof(*set)))
2403 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2405 spin_lock_irq(¤t->sighand->siglock);
2406 old_set = current->blocked.sig[0];
2414 sigaddsetmask(¤t->blocked, new_set);
2417 sigdelsetmask(¤t->blocked, new_set);
2420 current->blocked.sig[0] = new_set;
2424 recalc_sigpending();
2425 spin_unlock_irq(¤t->sighand->siglock);
2431 old_set = current->blocked.sig[0];
2434 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2441 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2443 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2445 sys_rt_sigaction(int sig,
2446 const struct sigaction __user *act,
2447 struct sigaction __user *oact,
2450 struct k_sigaction new_sa, old_sa;
2453 /* XXX: Don't preclude handling different sized sigset_t's. */
2454 if (sigsetsize != sizeof(sigset_t))
2458 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2462 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2465 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2471 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2473 #ifdef __ARCH_WANT_SYS_SGETMASK
2476 * For backwards compatibility. Functionality superseded by sigprocmask.
2482 return current->blocked.sig[0];
2486 sys_ssetmask(int newmask)
2490 spin_lock_irq(¤t->sighand->siglock);
2491 old = current->blocked.sig[0];
2493 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2495 recalc_sigpending();
2496 spin_unlock_irq(¤t->sighand->siglock);
2500 #endif /* __ARCH_WANT_SGETMASK */
2502 #ifdef __ARCH_WANT_SYS_SIGNAL
2504 * For backwards compatibility. Functionality superseded by sigaction.
2506 asmlinkage unsigned long
2507 sys_signal(int sig, __sighandler_t handler)
2509 struct k_sigaction new_sa, old_sa;
2512 new_sa.sa.sa_handler = handler;
2513 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2514 sigemptyset(&new_sa.sa.sa_mask);
2516 ret = do_sigaction(sig, &new_sa, &old_sa);
2518 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2520 #endif /* __ARCH_WANT_SYS_SIGNAL */
2522 #ifdef __ARCH_WANT_SYS_PAUSE
2527 current->state = TASK_INTERRUPTIBLE;
2529 return -ERESTARTNOHAND;
2534 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2535 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2539 /* XXX: Don't preclude handling different sized sigset_t's. */
2540 if (sigsetsize != sizeof(sigset_t))
2543 if (copy_from_user(&newset, unewset, sizeof(newset)))
2545 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2547 spin_lock_irq(¤t->sighand->siglock);
2548 current->saved_sigmask = current->blocked;
2549 current->blocked = newset;
2550 recalc_sigpending();
2551 spin_unlock_irq(¤t->sighand->siglock);
2553 current->state = TASK_INTERRUPTIBLE;
2555 set_thread_flag(TIF_RESTORE_SIGMASK);
2556 return -ERESTARTNOHAND;
2558 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2560 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2565 void __init signals_init(void)
2567 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);