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)
539 if (!valid_signal(sig))
542 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
545 error = audit_signal_info(sig, t); /* Let audit system see the signal */
549 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
550 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
551 !capable(CAP_KILL)) {
554 sid = task_session(t);
556 * We don't return the error if sid == NULL. The
557 * task was unhashed, the caller must notice this.
559 if (!sid || sid == task_session(current))
566 return security_task_kill(t, info, sig, 0);
570 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
573 * Handle magic process-wide effects of stop/continue signals. Unlike
574 * the signal actions, these happen immediately at signal-generation
575 * time regardless of blocking, ignoring, or handling. This does the
576 * actual continuing for SIGCONT, but not the actual stopping for stop
577 * signals. The process stop is done as a signal action for SIG_DFL.
579 * Returns true if the signal should be actually delivered, otherwise
580 * it should be dropped.
582 static int prepare_signal(int sig, struct task_struct *p)
584 struct signal_struct *signal = p->signal;
585 struct task_struct *t;
587 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
589 * The process is in the middle of dying, nothing to do.
591 } else if (sig_kernel_stop(sig)) {
593 * This is a stop signal. Remove SIGCONT from all queues.
595 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
598 rm_from_queue(sigmask(SIGCONT), &t->pending);
599 } while_each_thread(p, t);
600 } else if (sig == SIGCONT) {
603 * Remove all stop signals from all queues,
604 * and wake all threads.
606 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
610 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
612 * If there is a handler for SIGCONT, we must make
613 * sure that no thread returns to user mode before
614 * we post the signal, in case it was the only
615 * thread eligible to run the signal handler--then
616 * it must not do anything between resuming and
617 * running the handler. With the TIF_SIGPENDING
618 * flag set, the thread will pause and acquire the
619 * siglock that we hold now and until we've queued
620 * the pending signal.
622 * Wake up the stopped thread _after_ setting
625 state = __TASK_STOPPED;
626 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
627 set_tsk_thread_flag(t, TIF_SIGPENDING);
628 state |= TASK_INTERRUPTIBLE;
630 wake_up_state(t, state);
631 } while_each_thread(p, t);
634 * Notify the parent with CLD_CONTINUED if we were stopped.
636 * If we were in the middle of a group stop, we pretend it
637 * was already finished, and then continued. Since SIGCHLD
638 * doesn't queue we report only CLD_STOPPED, as if the next
639 * CLD_CONTINUED was dropped.
642 if (signal->flags & SIGNAL_STOP_STOPPED)
643 why |= SIGNAL_CLD_CONTINUED;
644 else if (signal->group_stop_count)
645 why |= SIGNAL_CLD_STOPPED;
649 * The first thread which returns from finish_stop()
650 * will take ->siglock, notice SIGNAL_CLD_MASK, and
651 * notify its parent. See get_signal_to_deliver().
653 signal->flags = why | SIGNAL_STOP_CONTINUED;
654 signal->group_stop_count = 0;
655 signal->group_exit_code = 0;
658 * We are not stopped, but there could be a stop
659 * signal in the middle of being processed after
660 * being removed from the queue. Clear that too.
662 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
666 return !sig_ignored(p, sig);
670 * Test if P wants to take SIG. After we've checked all threads with this,
671 * it's equivalent to finding no threads not blocking SIG. Any threads not
672 * blocking SIG were ruled out because they are not running and already
673 * have pending signals. Such threads will dequeue from the shared queue
674 * as soon as they're available, so putting the signal on the shared queue
675 * will be equivalent to sending it to one such thread.
677 static inline int wants_signal(int sig, struct task_struct *p)
679 if (sigismember(&p->blocked, sig))
681 if (p->flags & PF_EXITING)
685 if (task_is_stopped_or_traced(p))
687 return task_curr(p) || !signal_pending(p);
690 static void complete_signal(int sig, struct task_struct *p, int group)
692 struct signal_struct *signal = p->signal;
693 struct task_struct *t;
696 * Now find a thread we can wake up to take the signal off the queue.
698 * If the main thread wants the signal, it gets first crack.
699 * Probably the least surprising to the average bear.
701 if (wants_signal(sig, p))
703 else if (!group || thread_group_empty(p))
705 * There is just one thread and it does not need to be woken.
706 * It will dequeue unblocked signals before it runs again.
711 * Otherwise try to find a suitable thread.
713 t = signal->curr_target;
714 while (!wants_signal(sig, t)) {
716 if (t == signal->curr_target)
718 * No thread needs to be woken.
719 * Any eligible threads will see
720 * the signal in the queue soon.
724 signal->curr_target = t;
728 * Found a killable thread. If the signal will be fatal,
729 * then start taking the whole group down immediately.
731 if (sig_fatal(p, sig) &&
732 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
733 !sigismember(&t->real_blocked, sig) &&
734 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
736 * This signal will be fatal to the whole group.
738 if (!sig_kernel_coredump(sig)) {
740 * Start a group exit and wake everybody up.
741 * This way we don't have other threads
742 * running and doing things after a slower
743 * thread has the fatal signal pending.
745 signal->flags = SIGNAL_GROUP_EXIT;
746 signal->group_exit_code = sig;
747 signal->group_stop_count = 0;
750 sigaddset(&t->pending.signal, SIGKILL);
751 signal_wake_up(t, 1);
752 } while_each_thread(p, t);
758 * The signal is already in the shared-pending queue.
759 * Tell the chosen thread to wake up and dequeue it.
761 signal_wake_up(t, sig == SIGKILL);
765 static inline int legacy_queue(struct sigpending *signals, int sig)
767 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
770 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
773 struct sigpending *pending;
776 assert_spin_locked(&t->sighand->siglock);
777 if (!prepare_signal(sig, t))
780 pending = group ? &t->signal->shared_pending : &t->pending;
782 * Short-circuit ignored signals and support queuing
783 * exactly one non-rt signal, so that we can get more
784 * detailed information about the cause of the signal.
786 if (legacy_queue(pending, sig))
789 * fast-pathed signals for kernel-internal things like SIGSTOP
792 if (info == SEND_SIG_FORCED)
795 /* Real-time signals must be queued if sent by sigqueue, or
796 some other real-time mechanism. It is implementation
797 defined whether kill() does so. We attempt to do so, on
798 the principle of least surprise, but since kill is not
799 allowed to fail with EAGAIN when low on memory we just
800 make sure at least one signal gets delivered and don't
801 pass on the info struct. */
803 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
804 (is_si_special(info) ||
805 info->si_code >= 0)));
807 list_add_tail(&q->list, &pending->list);
808 switch ((unsigned long) info) {
809 case (unsigned long) SEND_SIG_NOINFO:
810 q->info.si_signo = sig;
811 q->info.si_errno = 0;
812 q->info.si_code = SI_USER;
813 q->info.si_pid = task_pid_vnr(current);
814 q->info.si_uid = current->uid;
816 case (unsigned long) SEND_SIG_PRIV:
817 q->info.si_signo = sig;
818 q->info.si_errno = 0;
819 q->info.si_code = SI_KERNEL;
824 copy_siginfo(&q->info, info);
827 } else if (!is_si_special(info)) {
828 if (sig >= SIGRTMIN && info->si_code != SI_USER)
830 * Queue overflow, abort. We may abort if the signal was rt
831 * and sent by user using something other than kill().
837 signalfd_notify(t, sig);
838 sigaddset(&pending->signal, sig);
839 complete_signal(sig, t, group);
843 int print_fatal_signals;
845 static void print_fatal_signal(struct pt_regs *regs, int signr)
847 printk("%s/%d: potentially unexpected fatal signal %d.\n",
848 current->comm, task_pid_nr(current), signr);
850 #if defined(__i386__) && !defined(__arch_um__)
851 printk("code at %08lx: ", regs->ip);
854 for (i = 0; i < 16; i++) {
857 __get_user(insn, (unsigned char *)(regs->ip + i));
858 printk("%02x ", insn);
866 static int __init setup_print_fatal_signals(char *str)
868 get_option (&str, &print_fatal_signals);
873 __setup("print-fatal-signals=", setup_print_fatal_signals);
876 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
878 return send_signal(sig, info, p, 1);
882 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
884 return send_signal(sig, info, t, 0);
888 * Force a signal that the process can't ignore: if necessary
889 * we unblock the signal and change any SIG_IGN to SIG_DFL.
891 * Note: If we unblock the signal, we always reset it to SIG_DFL,
892 * since we do not want to have a signal handler that was blocked
893 * be invoked when user space had explicitly blocked it.
895 * We don't want to have recursive SIGSEGV's etc, for example.
898 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
900 unsigned long int flags;
901 int ret, blocked, ignored;
902 struct k_sigaction *action;
904 spin_lock_irqsave(&t->sighand->siglock, flags);
905 action = &t->sighand->action[sig-1];
906 ignored = action->sa.sa_handler == SIG_IGN;
907 blocked = sigismember(&t->blocked, sig);
908 if (blocked || ignored) {
909 action->sa.sa_handler = SIG_DFL;
911 sigdelset(&t->blocked, sig);
912 recalc_sigpending_and_wake(t);
915 ret = specific_send_sig_info(sig, info, t);
916 spin_unlock_irqrestore(&t->sighand->siglock, flags);
922 force_sig_specific(int sig, struct task_struct *t)
924 force_sig_info(sig, SEND_SIG_FORCED, t);
928 * Nuke all other threads in the group.
930 void zap_other_threads(struct task_struct *p)
932 struct task_struct *t;
934 p->signal->group_stop_count = 0;
936 for (t = next_thread(p); t != p; t = next_thread(t)) {
938 * Don't bother with already dead threads
943 /* SIGKILL will be handled before any pending SIGSTOP */
944 sigaddset(&t->pending.signal, SIGKILL);
945 signal_wake_up(t, 1);
949 int __fatal_signal_pending(struct task_struct *tsk)
951 return sigismember(&tsk->pending.signal, SIGKILL);
953 EXPORT_SYMBOL(__fatal_signal_pending);
955 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
957 struct sighand_struct *sighand;
961 sighand = rcu_dereference(tsk->sighand);
962 if (unlikely(sighand == NULL))
965 spin_lock_irqsave(&sighand->siglock, *flags);
966 if (likely(sighand == tsk->sighand))
968 spin_unlock_irqrestore(&sighand->siglock, *flags);
975 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
980 ret = check_kill_permission(sig, info, p);
984 if (lock_task_sighand(p, &flags)) {
985 ret = __group_send_sig_info(sig, info, p);
986 unlock_task_sighand(p, &flags);
994 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
995 * control characters do (^C, ^Z etc)
998 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1000 struct task_struct *p = NULL;
1001 int retval, success;
1005 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1006 int err = group_send_sig_info(sig, info, p);
1009 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1010 return success ? 0 : retval;
1013 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1016 struct task_struct *p;
1020 p = pid_task(pid, PIDTYPE_PID);
1022 error = group_send_sig_info(sig, info, p);
1023 if (unlikely(error == -ESRCH))
1025 * The task was unhashed in between, try again.
1026 * If it is dead, pid_task() will return NULL,
1027 * if we race with de_thread() it will find the
1038 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1042 error = kill_pid_info(sig, info, find_vpid(pid));
1047 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1048 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1049 uid_t uid, uid_t euid, u32 secid)
1052 struct task_struct *p;
1054 if (!valid_signal(sig))
1057 read_lock(&tasklist_lock);
1058 p = pid_task(pid, PIDTYPE_PID);
1063 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1064 && (euid != p->suid) && (euid != p->uid)
1065 && (uid != p->suid) && (uid != p->uid)) {
1069 ret = security_task_kill(p, info, sig, secid);
1072 if (sig && p->sighand) {
1073 unsigned long flags;
1074 spin_lock_irqsave(&p->sighand->siglock, flags);
1075 ret = __group_send_sig_info(sig, info, p);
1076 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1079 read_unlock(&tasklist_lock);
1082 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1085 * kill_something_info() interprets pid in interesting ways just like kill(2).
1087 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1088 * is probably wrong. Should make it like BSD or SYSV.
1091 static int kill_something_info(int sig, struct siginfo *info, int pid)
1097 ret = kill_pid_info(sig, info, find_vpid(pid));
1102 read_lock(&tasklist_lock);
1104 ret = __kill_pgrp_info(sig, info,
1105 pid ? find_vpid(-pid) : task_pgrp(current));
1107 int retval = 0, count = 0;
1108 struct task_struct * p;
1110 for_each_process(p) {
1111 if (p->pid > 1 && !same_thread_group(p, current)) {
1112 int err = group_send_sig_info(sig, info, p);
1118 ret = count ? retval : -ESRCH;
1120 read_unlock(&tasklist_lock);
1126 * These are for backward compatibility with the rest of the kernel source.
1130 * The caller must ensure the task can't exit.
1133 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1136 unsigned long flags;
1139 * Make sure legacy kernel users don't send in bad values
1140 * (normal paths check this in check_kill_permission).
1142 if (!valid_signal(sig))
1145 spin_lock_irqsave(&p->sighand->siglock, flags);
1146 ret = specific_send_sig_info(sig, info, p);
1147 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1151 #define __si_special(priv) \
1152 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1155 send_sig(int sig, struct task_struct *p, int priv)
1157 return send_sig_info(sig, __si_special(priv), p);
1161 force_sig(int sig, struct task_struct *p)
1163 force_sig_info(sig, SEND_SIG_PRIV, p);
1167 * When things go south during signal handling, we
1168 * will force a SIGSEGV. And if the signal that caused
1169 * the problem was already a SIGSEGV, we'll want to
1170 * make sure we don't even try to deliver the signal..
1173 force_sigsegv(int sig, struct task_struct *p)
1175 if (sig == SIGSEGV) {
1176 unsigned long flags;
1177 spin_lock_irqsave(&p->sighand->siglock, flags);
1178 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1179 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1181 force_sig(SIGSEGV, p);
1185 int kill_pgrp(struct pid *pid, int sig, int priv)
1189 read_lock(&tasklist_lock);
1190 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1191 read_unlock(&tasklist_lock);
1195 EXPORT_SYMBOL(kill_pgrp);
1197 int kill_pid(struct pid *pid, int sig, int priv)
1199 return kill_pid_info(sig, __si_special(priv), pid);
1201 EXPORT_SYMBOL(kill_pid);
1204 kill_proc(pid_t pid, int sig, int priv)
1209 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1215 * These functions support sending signals using preallocated sigqueue
1216 * structures. This is needed "because realtime applications cannot
1217 * afford to lose notifications of asynchronous events, like timer
1218 * expirations or I/O completions". In the case of Posix Timers
1219 * we allocate the sigqueue structure from the timer_create. If this
1220 * allocation fails we are able to report the failure to the application
1221 * with an EAGAIN error.
1224 struct sigqueue *sigqueue_alloc(void)
1228 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1229 q->flags |= SIGQUEUE_PREALLOC;
1233 void sigqueue_free(struct sigqueue *q)
1235 unsigned long flags;
1236 spinlock_t *lock = ¤t->sighand->siglock;
1238 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1240 * If the signal is still pending remove it from the
1241 * pending queue. We must hold ->siglock while testing
1242 * q->list to serialize with collect_signal().
1244 spin_lock_irqsave(lock, flags);
1245 if (!list_empty(&q->list))
1246 list_del_init(&q->list);
1247 spin_unlock_irqrestore(lock, flags);
1249 q->flags &= ~SIGQUEUE_PREALLOC;
1253 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1255 int sig = q->info.si_signo;
1256 struct sigpending *pending;
1257 unsigned long flags;
1260 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1263 if (!likely(lock_task_sighand(t, &flags)))
1266 ret = 1; /* the signal is ignored */
1267 if (!prepare_signal(sig, t))
1271 if (unlikely(!list_empty(&q->list))) {
1273 * If an SI_TIMER entry is already queue just increment
1274 * the overrun count.
1276 BUG_ON(q->info.si_code != SI_TIMER);
1277 q->info.si_overrun++;
1281 signalfd_notify(t, sig);
1282 pending = group ? &t->signal->shared_pending : &t->pending;
1283 list_add_tail(&q->list, &pending->list);
1284 sigaddset(&pending->signal, sig);
1285 complete_signal(sig, t, group);
1287 unlock_task_sighand(t, &flags);
1293 * Wake up any threads in the parent blocked in wait* syscalls.
1295 static inline void __wake_up_parent(struct task_struct *p,
1296 struct task_struct *parent)
1298 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1302 * Let a parent know about the death of a child.
1303 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1306 void do_notify_parent(struct task_struct *tsk, int sig)
1308 struct siginfo info;
1309 unsigned long flags;
1310 struct sighand_struct *psig;
1314 /* do_notify_parent_cldstop should have been called instead. */
1315 BUG_ON(task_is_stopped_or_traced(tsk));
1317 BUG_ON(!tsk->ptrace &&
1318 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1320 info.si_signo = sig;
1323 * we are under tasklist_lock here so our parent is tied to
1324 * us and cannot exit and release its namespace.
1326 * the only it can is to switch its nsproxy with sys_unshare,
1327 * bu uncharing pid namespaces is not allowed, so we'll always
1328 * see relevant namespace
1330 * write_lock() currently calls preempt_disable() which is the
1331 * same as rcu_read_lock(), but according to Oleg, this is not
1332 * correct to rely on this
1335 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1338 info.si_uid = tsk->uid;
1340 /* FIXME: find out whether or not this is supposed to be c*time. */
1341 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1342 tsk->signal->utime));
1343 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1344 tsk->signal->stime));
1346 info.si_status = tsk->exit_code & 0x7f;
1347 if (tsk->exit_code & 0x80)
1348 info.si_code = CLD_DUMPED;
1349 else if (tsk->exit_code & 0x7f)
1350 info.si_code = CLD_KILLED;
1352 info.si_code = CLD_EXITED;
1353 info.si_status = tsk->exit_code >> 8;
1356 psig = tsk->parent->sighand;
1357 spin_lock_irqsave(&psig->siglock, flags);
1358 if (!tsk->ptrace && sig == SIGCHLD &&
1359 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1360 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1362 * We are exiting and our parent doesn't care. POSIX.1
1363 * defines special semantics for setting SIGCHLD to SIG_IGN
1364 * or setting the SA_NOCLDWAIT flag: we should be reaped
1365 * automatically and not left for our parent's wait4 call.
1366 * Rather than having the parent do it as a magic kind of
1367 * signal handler, we just set this to tell do_exit that we
1368 * can be cleaned up without becoming a zombie. Note that
1369 * we still call __wake_up_parent in this case, because a
1370 * blocked sys_wait4 might now return -ECHILD.
1372 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1373 * is implementation-defined: we do (if you don't want
1374 * it, just use SIG_IGN instead).
1376 tsk->exit_signal = -1;
1377 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1380 if (valid_signal(sig) && sig > 0)
1381 __group_send_sig_info(sig, &info, tsk->parent);
1382 __wake_up_parent(tsk, tsk->parent);
1383 spin_unlock_irqrestore(&psig->siglock, flags);
1386 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1388 struct siginfo info;
1389 unsigned long flags;
1390 struct task_struct *parent;
1391 struct sighand_struct *sighand;
1393 if (tsk->ptrace & PT_PTRACED)
1394 parent = tsk->parent;
1396 tsk = tsk->group_leader;
1397 parent = tsk->real_parent;
1400 info.si_signo = SIGCHLD;
1403 * see comment in do_notify_parent() abot the following 3 lines
1406 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1409 info.si_uid = tsk->uid;
1411 /* FIXME: find out whether or not this is supposed to be c*time. */
1412 info.si_utime = cputime_to_jiffies(tsk->utime);
1413 info.si_stime = cputime_to_jiffies(tsk->stime);
1418 info.si_status = SIGCONT;
1421 info.si_status = tsk->signal->group_exit_code & 0x7f;
1424 info.si_status = tsk->exit_code & 0x7f;
1430 sighand = parent->sighand;
1431 spin_lock_irqsave(&sighand->siglock, flags);
1432 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1433 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1434 __group_send_sig_info(SIGCHLD, &info, parent);
1436 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1438 __wake_up_parent(tsk, parent);
1439 spin_unlock_irqrestore(&sighand->siglock, flags);
1442 static inline int may_ptrace_stop(void)
1444 if (!likely(current->ptrace & PT_PTRACED))
1447 * Are we in the middle of do_coredump?
1448 * If so and our tracer is also part of the coredump stopping
1449 * is a deadlock situation, and pointless because our tracer
1450 * is dead so don't allow us to stop.
1451 * If SIGKILL was already sent before the caller unlocked
1452 * ->siglock we must see ->core_waiters != 0. Otherwise it
1453 * is safe to enter schedule().
1455 if (unlikely(current->mm->core_waiters) &&
1456 unlikely(current->mm == current->parent->mm))
1463 * Return nonzero if there is a SIGKILL that should be waking us up.
1464 * Called with the siglock held.
1466 static int sigkill_pending(struct task_struct *tsk)
1468 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1469 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1470 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1474 * This must be called with current->sighand->siglock held.
1476 * This should be the path for all ptrace stops.
1477 * We always set current->last_siginfo while stopped here.
1478 * That makes it a way to test a stopped process for
1479 * being ptrace-stopped vs being job-control-stopped.
1481 * If we actually decide not to stop at all because the tracer
1482 * is gone, we keep current->exit_code unless clear_code.
1484 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1488 if (arch_ptrace_stop_needed(exit_code, info)) {
1490 * The arch code has something special to do before a
1491 * ptrace stop. This is allowed to block, e.g. for faults
1492 * on user stack pages. We can't keep the siglock while
1493 * calling arch_ptrace_stop, so we must release it now.
1494 * To preserve proper semantics, we must do this before
1495 * any signal bookkeeping like checking group_stop_count.
1496 * Meanwhile, a SIGKILL could come in before we retake the
1497 * siglock. That must prevent us from sleeping in TASK_TRACED.
1498 * So after regaining the lock, we must check for SIGKILL.
1500 spin_unlock_irq(¤t->sighand->siglock);
1501 arch_ptrace_stop(exit_code, info);
1502 spin_lock_irq(¤t->sighand->siglock);
1503 killed = sigkill_pending(current);
1507 * If there is a group stop in progress,
1508 * we must participate in the bookkeeping.
1510 if (current->signal->group_stop_count > 0)
1511 --current->signal->group_stop_count;
1513 current->last_siginfo = info;
1514 current->exit_code = exit_code;
1516 /* Let the debugger run. */
1517 __set_current_state(TASK_TRACED);
1518 spin_unlock_irq(¤t->sighand->siglock);
1519 read_lock(&tasklist_lock);
1520 if (!unlikely(killed) && may_ptrace_stop()) {
1521 do_notify_parent_cldstop(current, CLD_TRAPPED);
1522 read_unlock(&tasklist_lock);
1526 * By the time we got the lock, our tracer went away.
1527 * Don't drop the lock yet, another tracer may come.
1529 __set_current_state(TASK_RUNNING);
1531 current->exit_code = 0;
1532 read_unlock(&tasklist_lock);
1536 * While in TASK_TRACED, we were considered "frozen enough".
1537 * Now that we woke up, it's crucial if we're supposed to be
1538 * frozen that we freeze now before running anything substantial.
1543 * We are back. Now reacquire the siglock before touching
1544 * last_siginfo, so that we are sure to have synchronized with
1545 * any signal-sending on another CPU that wants to examine it.
1547 spin_lock_irq(¤t->sighand->siglock);
1548 current->last_siginfo = NULL;
1551 * Queued signals ignored us while we were stopped for tracing.
1552 * So check for any that we should take before resuming user mode.
1553 * This sets TIF_SIGPENDING, but never clears it.
1555 recalc_sigpending_tsk(current);
1558 void ptrace_notify(int exit_code)
1562 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1564 memset(&info, 0, sizeof info);
1565 info.si_signo = SIGTRAP;
1566 info.si_code = exit_code;
1567 info.si_pid = task_pid_vnr(current);
1568 info.si_uid = current->uid;
1570 /* Let the debugger run. */
1571 spin_lock_irq(¤t->sighand->siglock);
1572 ptrace_stop(exit_code, 1, &info);
1573 spin_unlock_irq(¤t->sighand->siglock);
1577 finish_stop(int stop_count)
1580 * If there are no other threads in the group, or if there is
1581 * a group stop in progress and we are the last to stop,
1582 * report to the parent. When ptraced, every thread reports itself.
1584 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1585 read_lock(&tasklist_lock);
1586 do_notify_parent_cldstop(current, CLD_STOPPED);
1587 read_unlock(&tasklist_lock);
1592 } while (try_to_freeze());
1594 * Now we don't run again until continued.
1596 current->exit_code = 0;
1600 * This performs the stopping for SIGSTOP and other stop signals.
1601 * We have to stop all threads in the thread group.
1602 * Returns nonzero if we've actually stopped and released the siglock.
1603 * Returns zero if we didn't stop and still hold the siglock.
1605 static int do_signal_stop(int signr)
1607 struct signal_struct *sig = current->signal;
1610 if (sig->group_stop_count > 0) {
1612 * There is a group stop in progress. We don't need to
1613 * start another one.
1615 stop_count = --sig->group_stop_count;
1617 struct task_struct *t;
1619 if (unlikely((sig->flags & (SIGNAL_STOP_DEQUEUED | SIGNAL_UNKILLABLE))
1620 != SIGNAL_STOP_DEQUEUED) ||
1621 unlikely(signal_group_exit(sig)))
1624 * There is no group stop already in progress.
1625 * We must initiate one now.
1627 sig->group_exit_code = signr;
1630 for (t = next_thread(current); t != current; t = next_thread(t))
1632 * Setting state to TASK_STOPPED for a group
1633 * stop is always done with the siglock held,
1634 * so this check has no races.
1636 if (!(t->flags & PF_EXITING) &&
1637 !task_is_stopped_or_traced(t)) {
1639 signal_wake_up(t, 0);
1641 sig->group_stop_count = stop_count;
1644 if (stop_count == 0)
1645 sig->flags = SIGNAL_STOP_STOPPED;
1646 current->exit_code = sig->group_exit_code;
1647 __set_current_state(TASK_STOPPED);
1649 spin_unlock_irq(¤t->sighand->siglock);
1650 finish_stop(stop_count);
1654 static int ptrace_signal(int signr, siginfo_t *info,
1655 struct pt_regs *regs, void *cookie)
1657 if (!(current->ptrace & PT_PTRACED))
1660 ptrace_signal_deliver(regs, cookie);
1662 /* Let the debugger run. */
1663 ptrace_stop(signr, 0, info);
1665 /* We're back. Did the debugger cancel the sig? */
1666 signr = current->exit_code;
1670 current->exit_code = 0;
1672 /* Update the siginfo structure if the signal has
1673 changed. If the debugger wanted something
1674 specific in the siginfo structure then it should
1675 have updated *info via PTRACE_SETSIGINFO. */
1676 if (signr != info->si_signo) {
1677 info->si_signo = signr;
1679 info->si_code = SI_USER;
1680 info->si_pid = task_pid_vnr(current->parent);
1681 info->si_uid = current->parent->uid;
1684 /* If the (new) signal is now blocked, requeue it. */
1685 if (sigismember(¤t->blocked, signr)) {
1686 specific_send_sig_info(signr, info, current);
1693 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1694 struct pt_regs *regs, void *cookie)
1696 struct sighand_struct *sighand = current->sighand;
1697 struct signal_struct *signal = current->signal;
1702 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1703 * While in TASK_STOPPED, we were considered "frozen enough".
1704 * Now that we woke up, it's crucial if we're supposed to be
1705 * frozen that we freeze now before running anything substantial.
1709 spin_lock_irq(&sighand->siglock);
1711 * Every stopped thread goes here after wakeup. Check to see if
1712 * we should notify the parent, prepare_signal(SIGCONT) encodes
1713 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1715 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1716 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1717 ? CLD_CONTINUED : CLD_STOPPED;
1718 signal->flags &= ~SIGNAL_CLD_MASK;
1719 spin_unlock_irq(&sighand->siglock);
1721 read_lock(&tasklist_lock);
1722 do_notify_parent_cldstop(current->group_leader, why);
1723 read_unlock(&tasklist_lock);
1728 struct k_sigaction *ka;
1730 if (unlikely(signal->group_stop_count > 0) &&
1734 signr = dequeue_signal(current, ¤t->blocked, info);
1736 break; /* will return 0 */
1738 if (signr != SIGKILL) {
1739 signr = ptrace_signal(signr, info, regs, cookie);
1744 ka = &sighand->action[signr-1];
1745 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1747 if (ka->sa.sa_handler != SIG_DFL) {
1748 /* Run the handler. */
1751 if (ka->sa.sa_flags & SA_ONESHOT)
1752 ka->sa.sa_handler = SIG_DFL;
1754 break; /* will return non-zero "signr" value */
1758 * Now we are doing the default action for this signal.
1760 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1764 * Global init gets no signals it doesn't want.
1766 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1767 !signal_group_exit(signal))
1770 if (sig_kernel_stop(signr)) {
1772 * The default action is to stop all threads in
1773 * the thread group. The job control signals
1774 * do nothing in an orphaned pgrp, but SIGSTOP
1775 * always works. Note that siglock needs to be
1776 * dropped during the call to is_orphaned_pgrp()
1777 * because of lock ordering with tasklist_lock.
1778 * This allows an intervening SIGCONT to be posted.
1779 * We need to check for that and bail out if necessary.
1781 if (signr != SIGSTOP) {
1782 spin_unlock_irq(&sighand->siglock);
1784 /* signals can be posted during this window */
1786 if (is_current_pgrp_orphaned())
1789 spin_lock_irq(&sighand->siglock);
1792 if (likely(do_signal_stop(signr))) {
1793 /* It released the siglock. */
1798 * We didn't actually stop, due to a race
1799 * with SIGCONT or something like that.
1804 spin_unlock_irq(&sighand->siglock);
1807 * Anything else is fatal, maybe with a core dump.
1809 current->flags |= PF_SIGNALED;
1811 if (sig_kernel_coredump(signr)) {
1812 if (print_fatal_signals)
1813 print_fatal_signal(regs, signr);
1815 * If it was able to dump core, this kills all
1816 * other threads in the group and synchronizes with
1817 * their demise. If we lost the race with another
1818 * thread getting here, it set group_exit_code
1819 * first and our do_group_exit call below will use
1820 * that value and ignore the one we pass it.
1822 do_coredump((long)signr, signr, regs);
1826 * Death signals, no core dump.
1828 do_group_exit(signr);
1831 spin_unlock_irq(&sighand->siglock);
1835 void exit_signals(struct task_struct *tsk)
1838 struct task_struct *t;
1840 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1841 tsk->flags |= PF_EXITING;
1845 spin_lock_irq(&tsk->sighand->siglock);
1847 * From now this task is not visible for group-wide signals,
1848 * see wants_signal(), do_signal_stop().
1850 tsk->flags |= PF_EXITING;
1851 if (!signal_pending(tsk))
1854 /* It could be that __group_complete_signal() choose us to
1855 * notify about group-wide signal. Another thread should be
1856 * woken now to take the signal since we will not.
1858 for (t = tsk; (t = next_thread(t)) != tsk; )
1859 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1860 recalc_sigpending_and_wake(t);
1862 if (unlikely(tsk->signal->group_stop_count) &&
1863 !--tsk->signal->group_stop_count) {
1864 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1868 spin_unlock_irq(&tsk->sighand->siglock);
1870 if (unlikely(group_stop)) {
1871 read_lock(&tasklist_lock);
1872 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1873 read_unlock(&tasklist_lock);
1877 EXPORT_SYMBOL(recalc_sigpending);
1878 EXPORT_SYMBOL_GPL(dequeue_signal);
1879 EXPORT_SYMBOL(flush_signals);
1880 EXPORT_SYMBOL(force_sig);
1881 EXPORT_SYMBOL(kill_proc);
1882 EXPORT_SYMBOL(ptrace_notify);
1883 EXPORT_SYMBOL(send_sig);
1884 EXPORT_SYMBOL(send_sig_info);
1885 EXPORT_SYMBOL(sigprocmask);
1886 EXPORT_SYMBOL(block_all_signals);
1887 EXPORT_SYMBOL(unblock_all_signals);
1891 * System call entry points.
1894 asmlinkage long sys_restart_syscall(void)
1896 struct restart_block *restart = ¤t_thread_info()->restart_block;
1897 return restart->fn(restart);
1900 long do_no_restart_syscall(struct restart_block *param)
1906 * We don't need to get the kernel lock - this is all local to this
1907 * particular thread.. (and that's good, because this is _heavily_
1908 * used by various programs)
1912 * This is also useful for kernel threads that want to temporarily
1913 * (or permanently) block certain signals.
1915 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1916 * interface happily blocks "unblockable" signals like SIGKILL
1919 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1923 spin_lock_irq(¤t->sighand->siglock);
1925 *oldset = current->blocked;
1930 sigorsets(¤t->blocked, ¤t->blocked, set);
1933 signandsets(¤t->blocked, ¤t->blocked, set);
1936 current->blocked = *set;
1941 recalc_sigpending();
1942 spin_unlock_irq(¤t->sighand->siglock);
1948 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1950 int error = -EINVAL;
1951 sigset_t old_set, new_set;
1953 /* XXX: Don't preclude handling different sized sigset_t's. */
1954 if (sigsetsize != sizeof(sigset_t))
1959 if (copy_from_user(&new_set, set, sizeof(*set)))
1961 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1963 error = sigprocmask(how, &new_set, &old_set);
1969 spin_lock_irq(¤t->sighand->siglock);
1970 old_set = current->blocked;
1971 spin_unlock_irq(¤t->sighand->siglock);
1975 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1983 long do_sigpending(void __user *set, unsigned long sigsetsize)
1985 long error = -EINVAL;
1988 if (sigsetsize > sizeof(sigset_t))
1991 spin_lock_irq(¤t->sighand->siglock);
1992 sigorsets(&pending, ¤t->pending.signal,
1993 ¤t->signal->shared_pending.signal);
1994 spin_unlock_irq(¤t->sighand->siglock);
1996 /* Outside the lock because only this thread touches it. */
1997 sigandsets(&pending, ¤t->blocked, &pending);
2000 if (!copy_to_user(set, &pending, sigsetsize))
2008 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2010 return do_sigpending(set, sigsetsize);
2013 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2015 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2019 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2021 if (from->si_code < 0)
2022 return __copy_to_user(to, from, sizeof(siginfo_t))
2025 * If you change siginfo_t structure, please be sure
2026 * this code is fixed accordingly.
2027 * Please remember to update the signalfd_copyinfo() function
2028 * inside fs/signalfd.c too, in case siginfo_t changes.
2029 * It should never copy any pad contained in the structure
2030 * to avoid security leaks, but must copy the generic
2031 * 3 ints plus the relevant union member.
2033 err = __put_user(from->si_signo, &to->si_signo);
2034 err |= __put_user(from->si_errno, &to->si_errno);
2035 err |= __put_user((short)from->si_code, &to->si_code);
2036 switch (from->si_code & __SI_MASK) {
2038 err |= __put_user(from->si_pid, &to->si_pid);
2039 err |= __put_user(from->si_uid, &to->si_uid);
2042 err |= __put_user(from->si_tid, &to->si_tid);
2043 err |= __put_user(from->si_overrun, &to->si_overrun);
2044 err |= __put_user(from->si_ptr, &to->si_ptr);
2047 err |= __put_user(from->si_band, &to->si_band);
2048 err |= __put_user(from->si_fd, &to->si_fd);
2051 err |= __put_user(from->si_addr, &to->si_addr);
2052 #ifdef __ARCH_SI_TRAPNO
2053 err |= __put_user(from->si_trapno, &to->si_trapno);
2057 err |= __put_user(from->si_pid, &to->si_pid);
2058 err |= __put_user(from->si_uid, &to->si_uid);
2059 err |= __put_user(from->si_status, &to->si_status);
2060 err |= __put_user(from->si_utime, &to->si_utime);
2061 err |= __put_user(from->si_stime, &to->si_stime);
2063 case __SI_RT: /* This is not generated by the kernel as of now. */
2064 case __SI_MESGQ: /* But this is */
2065 err |= __put_user(from->si_pid, &to->si_pid);
2066 err |= __put_user(from->si_uid, &to->si_uid);
2067 err |= __put_user(from->si_ptr, &to->si_ptr);
2069 default: /* this is just in case for now ... */
2070 err |= __put_user(from->si_pid, &to->si_pid);
2071 err |= __put_user(from->si_uid, &to->si_uid);
2080 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2081 siginfo_t __user *uinfo,
2082 const struct timespec __user *uts,
2091 /* XXX: Don't preclude handling different sized sigset_t's. */
2092 if (sigsetsize != sizeof(sigset_t))
2095 if (copy_from_user(&these, uthese, sizeof(these)))
2099 * Invert the set of allowed signals to get those we
2102 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2106 if (copy_from_user(&ts, uts, sizeof(ts)))
2108 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2113 spin_lock_irq(¤t->sighand->siglock);
2114 sig = dequeue_signal(current, &these, &info);
2116 timeout = MAX_SCHEDULE_TIMEOUT;
2118 timeout = (timespec_to_jiffies(&ts)
2119 + (ts.tv_sec || ts.tv_nsec));
2122 /* None ready -- temporarily unblock those we're
2123 * interested while we are sleeping in so that we'll
2124 * be awakened when they arrive. */
2125 current->real_blocked = current->blocked;
2126 sigandsets(¤t->blocked, ¤t->blocked, &these);
2127 recalc_sigpending();
2128 spin_unlock_irq(¤t->sighand->siglock);
2130 timeout = schedule_timeout_interruptible(timeout);
2132 spin_lock_irq(¤t->sighand->siglock);
2133 sig = dequeue_signal(current, &these, &info);
2134 current->blocked = current->real_blocked;
2135 siginitset(¤t->real_blocked, 0);
2136 recalc_sigpending();
2139 spin_unlock_irq(¤t->sighand->siglock);
2144 if (copy_siginfo_to_user(uinfo, &info))
2157 sys_kill(int pid, int sig)
2159 struct siginfo info;
2161 info.si_signo = sig;
2163 info.si_code = SI_USER;
2164 info.si_pid = task_tgid_vnr(current);
2165 info.si_uid = current->uid;
2167 return kill_something_info(sig, &info, pid);
2170 static int do_tkill(int tgid, int pid, int sig)
2173 struct siginfo info;
2174 struct task_struct *p;
2175 unsigned long flags;
2178 info.si_signo = sig;
2180 info.si_code = SI_TKILL;
2181 info.si_pid = task_tgid_vnr(current);
2182 info.si_uid = current->uid;
2185 p = find_task_by_vpid(pid);
2186 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2187 error = check_kill_permission(sig, &info, p);
2189 * The null signal is a permissions and process existence
2190 * probe. No signal is actually delivered.
2192 * If lock_task_sighand() fails we pretend the task dies
2193 * after receiving the signal. The window is tiny, and the
2194 * signal is private anyway.
2196 if (!error && sig && lock_task_sighand(p, &flags)) {
2197 error = specific_send_sig_info(sig, &info, p);
2198 unlock_task_sighand(p, &flags);
2207 * sys_tgkill - send signal to one specific thread
2208 * @tgid: the thread group ID of the thread
2209 * @pid: the PID of the thread
2210 * @sig: signal to be sent
2212 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2213 * exists but it's not belonging to the target process anymore. This
2214 * method solves the problem of threads exiting and PIDs getting reused.
2216 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2218 /* This is only valid for single tasks */
2219 if (pid <= 0 || tgid <= 0)
2222 return do_tkill(tgid, pid, sig);
2226 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2229 sys_tkill(int pid, int sig)
2231 /* This is only valid for single tasks */
2235 return do_tkill(0, pid, sig);
2239 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2243 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2246 /* Not even root can pretend to send signals from the kernel.
2247 Nor can they impersonate a kill(), which adds source info. */
2248 if (info.si_code >= 0)
2250 info.si_signo = sig;
2252 /* POSIX.1b doesn't mention process groups. */
2253 return kill_proc_info(sig, &info, pid);
2256 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2258 struct task_struct *t = current;
2259 struct k_sigaction *k;
2262 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2265 k = &t->sighand->action[sig-1];
2267 spin_lock_irq(¤t->sighand->siglock);
2272 sigdelsetmask(&act->sa.sa_mask,
2273 sigmask(SIGKILL) | sigmask(SIGSTOP));
2277 * "Setting a signal action to SIG_IGN for a signal that is
2278 * pending shall cause the pending signal to be discarded,
2279 * whether or not it is blocked."
2281 * "Setting a signal action to SIG_DFL for a signal that is
2282 * pending and whose default action is to ignore the signal
2283 * (for example, SIGCHLD), shall cause the pending signal to
2284 * be discarded, whether or not it is blocked"
2286 if (__sig_ignored(t, sig)) {
2288 sigaddset(&mask, sig);
2289 rm_from_queue_full(&mask, &t->signal->shared_pending);
2291 rm_from_queue_full(&mask, &t->pending);
2293 } while (t != current);
2297 spin_unlock_irq(¤t->sighand->siglock);
2302 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2308 oss.ss_sp = (void __user *) current->sas_ss_sp;
2309 oss.ss_size = current->sas_ss_size;
2310 oss.ss_flags = sas_ss_flags(sp);
2319 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2320 || __get_user(ss_sp, &uss->ss_sp)
2321 || __get_user(ss_flags, &uss->ss_flags)
2322 || __get_user(ss_size, &uss->ss_size))
2326 if (on_sig_stack(sp))
2332 * Note - this code used to test ss_flags incorrectly
2333 * old code may have been written using ss_flags==0
2334 * to mean ss_flags==SS_ONSTACK (as this was the only
2335 * way that worked) - this fix preserves that older
2338 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2341 if (ss_flags == SS_DISABLE) {
2346 if (ss_size < MINSIGSTKSZ)
2350 current->sas_ss_sp = (unsigned long) ss_sp;
2351 current->sas_ss_size = ss_size;
2356 if (copy_to_user(uoss, &oss, sizeof(oss)))
2365 #ifdef __ARCH_WANT_SYS_SIGPENDING
2368 sys_sigpending(old_sigset_t __user *set)
2370 return do_sigpending(set, sizeof(*set));
2375 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2376 /* Some platforms have their own version with special arguments others
2377 support only sys_rt_sigprocmask. */
2380 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2383 old_sigset_t old_set, new_set;
2387 if (copy_from_user(&new_set, set, sizeof(*set)))
2389 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2391 spin_lock_irq(¤t->sighand->siglock);
2392 old_set = current->blocked.sig[0];
2400 sigaddsetmask(¤t->blocked, new_set);
2403 sigdelsetmask(¤t->blocked, new_set);
2406 current->blocked.sig[0] = new_set;
2410 recalc_sigpending();
2411 spin_unlock_irq(¤t->sighand->siglock);
2417 old_set = current->blocked.sig[0];
2420 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2427 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2429 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2431 sys_rt_sigaction(int sig,
2432 const struct sigaction __user *act,
2433 struct sigaction __user *oact,
2436 struct k_sigaction new_sa, old_sa;
2439 /* XXX: Don't preclude handling different sized sigset_t's. */
2440 if (sigsetsize != sizeof(sigset_t))
2444 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2448 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2451 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2457 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2459 #ifdef __ARCH_WANT_SYS_SGETMASK
2462 * For backwards compatibility. Functionality superseded by sigprocmask.
2468 return current->blocked.sig[0];
2472 sys_ssetmask(int newmask)
2476 spin_lock_irq(¤t->sighand->siglock);
2477 old = current->blocked.sig[0];
2479 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2481 recalc_sigpending();
2482 spin_unlock_irq(¤t->sighand->siglock);
2486 #endif /* __ARCH_WANT_SGETMASK */
2488 #ifdef __ARCH_WANT_SYS_SIGNAL
2490 * For backwards compatibility. Functionality superseded by sigaction.
2492 asmlinkage unsigned long
2493 sys_signal(int sig, __sighandler_t handler)
2495 struct k_sigaction new_sa, old_sa;
2498 new_sa.sa.sa_handler = handler;
2499 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2500 sigemptyset(&new_sa.sa.sa_mask);
2502 ret = do_sigaction(sig, &new_sa, &old_sa);
2504 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2506 #endif /* __ARCH_WANT_SYS_SIGNAL */
2508 #ifdef __ARCH_WANT_SYS_PAUSE
2513 current->state = TASK_INTERRUPTIBLE;
2515 return -ERESTARTNOHAND;
2520 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2521 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2525 /* XXX: Don't preclude handling different sized sigset_t's. */
2526 if (sigsetsize != sizeof(sigset_t))
2529 if (copy_from_user(&newset, unewset, sizeof(newset)))
2531 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2533 spin_lock_irq(¤t->sighand->siglock);
2534 current->saved_sigmask = current->blocked;
2535 current->blocked = newset;
2536 recalc_sigpending();
2537 spin_unlock_irq(¤t->sighand->siglock);
2539 current->state = TASK_INTERRUPTIBLE;
2541 set_thread_flag(TIF_RESTORE_SIGMASK);
2542 return -ERESTARTNOHAND;
2544 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2546 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2551 void __init signals_init(void)
2553 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);