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 static void __flush_itimer_signals(struct sigpending *pending)
236 sigset_t signal, retain;
237 struct sigqueue *q, *n;
239 signal = pending->signal;
240 sigemptyset(&retain);
242 list_for_each_entry_safe(q, n, &pending->list, list) {
243 int sig = q->info.si_signo;
245 if (likely(q->info.si_code != SI_TIMER)) {
246 sigaddset(&retain, sig);
248 sigdelset(&signal, sig);
249 list_del_init(&q->list);
254 sigorsets(&pending->signal, &signal, &retain);
257 void flush_itimer_signals(void)
259 struct task_struct *tsk = current;
262 spin_lock_irqsave(&tsk->sighand->siglock, flags);
263 __flush_itimer_signals(&tsk->pending);
264 __flush_itimer_signals(&tsk->signal->shared_pending);
265 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
268 void ignore_signals(struct task_struct *t)
272 for (i = 0; i < _NSIG; ++i)
273 t->sighand->action[i].sa.sa_handler = SIG_IGN;
279 * Flush all handlers for a task.
283 flush_signal_handlers(struct task_struct *t, int force_default)
286 struct k_sigaction *ka = &t->sighand->action[0];
287 for (i = _NSIG ; i != 0 ; i--) {
288 if (force_default || ka->sa.sa_handler != SIG_IGN)
289 ka->sa.sa_handler = SIG_DFL;
291 sigemptyset(&ka->sa.sa_mask);
296 int unhandled_signal(struct task_struct *tsk, int sig)
298 if (is_global_init(tsk))
300 if (tsk->ptrace & PT_PTRACED)
302 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
303 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
307 /* Notify the system that a driver wants to block all signals for this
308 * process, and wants to be notified if any signals at all were to be
309 * sent/acted upon. If the notifier routine returns non-zero, then the
310 * signal will be acted upon after all. If the notifier routine returns 0,
311 * then then signal will be blocked. Only one block per process is
312 * allowed. priv is a pointer to private data that the notifier routine
313 * can use to determine if the signal should be blocked or not. */
316 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
320 spin_lock_irqsave(¤t->sighand->siglock, flags);
321 current->notifier_mask = mask;
322 current->notifier_data = priv;
323 current->notifier = notifier;
324 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
327 /* Notify the system that blocking has ended. */
330 unblock_all_signals(void)
334 spin_lock_irqsave(¤t->sighand->siglock, flags);
335 current->notifier = NULL;
336 current->notifier_data = NULL;
338 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
341 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
343 struct sigqueue *q, *first = NULL;
346 * Collect the siginfo appropriate to this signal. Check if
347 * there is another siginfo for the same signal.
349 list_for_each_entry(q, &list->list, list) {
350 if (q->info.si_signo == sig) {
357 sigdelset(&list->signal, sig);
361 list_del_init(&first->list);
362 copy_siginfo(info, &first->info);
363 __sigqueue_free(first);
365 /* Ok, it wasn't in the queue. This must be
366 a fast-pathed signal or we must have been
367 out of queue space. So zero out the info.
369 info->si_signo = sig;
378 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
381 int sig = next_signal(pending, mask);
384 if (current->notifier) {
385 if (sigismember(current->notifier_mask, sig)) {
386 if (!(current->notifier)(current->notifier_data)) {
387 clear_thread_flag(TIF_SIGPENDING);
393 if (!collect_signal(sig, pending, info))
401 * Dequeue a signal and return the element to the caller, which is
402 * expected to free it.
404 * All callers have to hold the siglock.
406 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
410 /* We only dequeue private signals from ourselves, we don't let
411 * signalfd steal them
413 signr = __dequeue_signal(&tsk->pending, mask, info);
415 signr = __dequeue_signal(&tsk->signal->shared_pending,
420 * itimers are process shared and we restart periodic
421 * itimers in the signal delivery path to prevent DoS
422 * attacks in the high resolution timer case. This is
423 * compliant with the old way of self restarting
424 * itimers, as the SIGALRM is a legacy signal and only
425 * queued once. Changing the restart behaviour to
426 * restart the timer in the signal dequeue path is
427 * reducing the timer noise on heavy loaded !highres
430 if (unlikely(signr == SIGALRM)) {
431 struct hrtimer *tmr = &tsk->signal->real_timer;
433 if (!hrtimer_is_queued(tmr) &&
434 tsk->signal->it_real_incr.tv64 != 0) {
435 hrtimer_forward(tmr, tmr->base->get_time(),
436 tsk->signal->it_real_incr);
437 hrtimer_restart(tmr);
446 if (unlikely(sig_kernel_stop(signr))) {
448 * Set a marker that we have dequeued a stop signal. Our
449 * caller might release the siglock and then the pending
450 * stop signal it is about to process is no longer in the
451 * pending bitmasks, but must still be cleared by a SIGCONT
452 * (and overruled by a SIGKILL). So those cases clear this
453 * shared flag after we've set it. Note that this flag may
454 * remain set after the signal we return is ignored or
455 * handled. That doesn't matter because its only purpose
456 * is to alert stop-signal processing code when another
457 * processor has come along and cleared the flag.
459 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
460 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
462 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
464 * Release the siglock to ensure proper locking order
465 * of timer locks outside of siglocks. Note, we leave
466 * irqs disabled here, since the posix-timers code is
467 * about to disable them again anyway.
469 spin_unlock(&tsk->sighand->siglock);
470 do_schedule_next_timer(info);
471 spin_lock(&tsk->sighand->siglock);
477 * Tell a process that it has a new active signal..
479 * NOTE! we rely on the previous spin_lock to
480 * lock interrupts for us! We can only be called with
481 * "siglock" held, and the local interrupt must
482 * have been disabled when that got acquired!
484 * No need to set need_resched since signal event passing
485 * goes through ->blocked
487 void signal_wake_up(struct task_struct *t, int resume)
491 set_tsk_thread_flag(t, TIF_SIGPENDING);
494 * For SIGKILL, we want to wake it up in the stopped/traced/killable
495 * case. We don't check t->state here because there is a race with it
496 * executing another processor and just now entering stopped state.
497 * By using wake_up_state, we ensure the process will wake up and
498 * handle its death signal.
500 mask = TASK_INTERRUPTIBLE;
502 mask |= TASK_WAKEKILL;
503 if (!wake_up_state(t, mask))
508 * Remove signals in mask from the pending set and queue.
509 * Returns 1 if any signals were found.
511 * All callers must be holding the siglock.
513 * This version takes a sigset mask and looks at all signals,
514 * not just those in the first mask word.
516 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
518 struct sigqueue *q, *n;
521 sigandsets(&m, mask, &s->signal);
522 if (sigisemptyset(&m))
525 signandsets(&s->signal, &s->signal, mask);
526 list_for_each_entry_safe(q, n, &s->list, list) {
527 if (sigismember(mask, q->info.si_signo)) {
528 list_del_init(&q->list);
535 * Remove signals in mask from the pending set and queue.
536 * Returns 1 if any signals were found.
538 * All callers must be holding the siglock.
540 static int rm_from_queue(unsigned long mask, struct sigpending *s)
542 struct sigqueue *q, *n;
544 if (!sigtestsetmask(&s->signal, mask))
547 sigdelsetmask(&s->signal, mask);
548 list_for_each_entry_safe(q, n, &s->list, list) {
549 if (q->info.si_signo < SIGRTMIN &&
550 (mask & sigmask(q->info.si_signo))) {
551 list_del_init(&q->list);
559 * Bad permissions for sending the signal
561 static int check_kill_permission(int sig, struct siginfo *info,
562 struct task_struct *t)
567 if (!valid_signal(sig))
570 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
573 error = audit_signal_info(sig, t); /* Let audit system see the signal */
577 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
578 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
579 !capable(CAP_KILL)) {
582 sid = task_session(t);
584 * We don't return the error if sid == NULL. The
585 * task was unhashed, the caller must notice this.
587 if (!sid || sid == task_session(current))
594 return security_task_kill(t, info, sig, 0);
598 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
601 * Handle magic process-wide effects of stop/continue signals. Unlike
602 * the signal actions, these happen immediately at signal-generation
603 * time regardless of blocking, ignoring, or handling. This does the
604 * actual continuing for SIGCONT, but not the actual stopping for stop
605 * signals. The process stop is done as a signal action for SIG_DFL.
607 * Returns true if the signal should be actually delivered, otherwise
608 * it should be dropped.
610 static int prepare_signal(int sig, struct task_struct *p)
612 struct signal_struct *signal = p->signal;
613 struct task_struct *t;
615 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
617 * The process is in the middle of dying, nothing to do.
619 } else if (sig_kernel_stop(sig)) {
621 * This is a stop signal. Remove SIGCONT from all queues.
623 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
626 rm_from_queue(sigmask(SIGCONT), &t->pending);
627 } while_each_thread(p, t);
628 } else if (sig == SIGCONT) {
631 * Remove all stop signals from all queues,
632 * and wake all threads.
634 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
638 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
640 * If there is a handler for SIGCONT, we must make
641 * sure that no thread returns to user mode before
642 * we post the signal, in case it was the only
643 * thread eligible to run the signal handler--then
644 * it must not do anything between resuming and
645 * running the handler. With the TIF_SIGPENDING
646 * flag set, the thread will pause and acquire the
647 * siglock that we hold now and until we've queued
648 * the pending signal.
650 * Wake up the stopped thread _after_ setting
653 state = __TASK_STOPPED;
654 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
655 set_tsk_thread_flag(t, TIF_SIGPENDING);
656 state |= TASK_INTERRUPTIBLE;
658 wake_up_state(t, state);
659 } while_each_thread(p, t);
662 * Notify the parent with CLD_CONTINUED if we were stopped.
664 * If we were in the middle of a group stop, we pretend it
665 * was already finished, and then continued. Since SIGCHLD
666 * doesn't queue we report only CLD_STOPPED, as if the next
667 * CLD_CONTINUED was dropped.
670 if (signal->flags & SIGNAL_STOP_STOPPED)
671 why |= SIGNAL_CLD_CONTINUED;
672 else if (signal->group_stop_count)
673 why |= SIGNAL_CLD_STOPPED;
677 * The first thread which returns from finish_stop()
678 * will take ->siglock, notice SIGNAL_CLD_MASK, and
679 * notify its parent. See get_signal_to_deliver().
681 signal->flags = why | SIGNAL_STOP_CONTINUED;
682 signal->group_stop_count = 0;
683 signal->group_exit_code = 0;
686 * We are not stopped, but there could be a stop
687 * signal in the middle of being processed after
688 * being removed from the queue. Clear that too.
690 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
694 return !sig_ignored(p, sig);
698 * Test if P wants to take SIG. After we've checked all threads with this,
699 * it's equivalent to finding no threads not blocking SIG. Any threads not
700 * blocking SIG were ruled out because they are not running and already
701 * have pending signals. Such threads will dequeue from the shared queue
702 * as soon as they're available, so putting the signal on the shared queue
703 * will be equivalent to sending it to one such thread.
705 static inline int wants_signal(int sig, struct task_struct *p)
707 if (sigismember(&p->blocked, sig))
709 if (p->flags & PF_EXITING)
713 if (task_is_stopped_or_traced(p))
715 return task_curr(p) || !signal_pending(p);
718 static void complete_signal(int sig, struct task_struct *p, int group)
720 struct signal_struct *signal = p->signal;
721 struct task_struct *t;
724 * Now find a thread we can wake up to take the signal off the queue.
726 * If the main thread wants the signal, it gets first crack.
727 * Probably the least surprising to the average bear.
729 if (wants_signal(sig, p))
731 else if (!group || thread_group_empty(p))
733 * There is just one thread and it does not need to be woken.
734 * It will dequeue unblocked signals before it runs again.
739 * Otherwise try to find a suitable thread.
741 t = signal->curr_target;
742 while (!wants_signal(sig, t)) {
744 if (t == signal->curr_target)
746 * No thread needs to be woken.
747 * Any eligible threads will see
748 * the signal in the queue soon.
752 signal->curr_target = t;
756 * Found a killable thread. If the signal will be fatal,
757 * then start taking the whole group down immediately.
759 if (sig_fatal(p, sig) &&
760 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
761 !sigismember(&t->real_blocked, sig) &&
762 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
764 * This signal will be fatal to the whole group.
766 if (!sig_kernel_coredump(sig)) {
768 * Start a group exit and wake everybody up.
769 * This way we don't have other threads
770 * running and doing things after a slower
771 * thread has the fatal signal pending.
773 signal->flags = SIGNAL_GROUP_EXIT;
774 signal->group_exit_code = sig;
775 signal->group_stop_count = 0;
778 sigaddset(&t->pending.signal, SIGKILL);
779 signal_wake_up(t, 1);
780 } while_each_thread(p, t);
786 * The signal is already in the shared-pending queue.
787 * Tell the chosen thread to wake up and dequeue it.
789 signal_wake_up(t, sig == SIGKILL);
793 static inline int legacy_queue(struct sigpending *signals, int sig)
795 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
798 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
801 struct sigpending *pending;
804 assert_spin_locked(&t->sighand->siglock);
805 if (!prepare_signal(sig, t))
808 pending = group ? &t->signal->shared_pending : &t->pending;
810 * Short-circuit ignored signals and support queuing
811 * exactly one non-rt signal, so that we can get more
812 * detailed information about the cause of the signal.
814 if (legacy_queue(pending, sig))
817 * fast-pathed signals for kernel-internal things like SIGSTOP
820 if (info == SEND_SIG_FORCED)
823 /* Real-time signals must be queued if sent by sigqueue, or
824 some other real-time mechanism. It is implementation
825 defined whether kill() does so. We attempt to do so, on
826 the principle of least surprise, but since kill is not
827 allowed to fail with EAGAIN when low on memory we just
828 make sure at least one signal gets delivered and don't
829 pass on the info struct. */
831 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
832 (is_si_special(info) ||
833 info->si_code >= 0)));
835 list_add_tail(&q->list, &pending->list);
836 switch ((unsigned long) info) {
837 case (unsigned long) SEND_SIG_NOINFO:
838 q->info.si_signo = sig;
839 q->info.si_errno = 0;
840 q->info.si_code = SI_USER;
841 q->info.si_pid = task_pid_vnr(current);
842 q->info.si_uid = current->uid;
844 case (unsigned long) SEND_SIG_PRIV:
845 q->info.si_signo = sig;
846 q->info.si_errno = 0;
847 q->info.si_code = SI_KERNEL;
852 copy_siginfo(&q->info, info);
855 } else if (!is_si_special(info)) {
856 if (sig >= SIGRTMIN && info->si_code != SI_USER)
858 * Queue overflow, abort. We may abort if the signal was rt
859 * and sent by user using something other than kill().
865 signalfd_notify(t, sig);
866 sigaddset(&pending->signal, sig);
867 complete_signal(sig, t, group);
871 int print_fatal_signals;
873 static void print_fatal_signal(struct pt_regs *regs, int signr)
875 printk("%s/%d: potentially unexpected fatal signal %d.\n",
876 current->comm, task_pid_nr(current), signr);
878 #if defined(__i386__) && !defined(__arch_um__)
879 printk("code at %08lx: ", regs->ip);
882 for (i = 0; i < 16; i++) {
885 __get_user(insn, (unsigned char *)(regs->ip + i));
886 printk("%02x ", insn);
894 static int __init setup_print_fatal_signals(char *str)
896 get_option (&str, &print_fatal_signals);
901 __setup("print-fatal-signals=", setup_print_fatal_signals);
904 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
906 return send_signal(sig, info, p, 1);
910 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
912 return send_signal(sig, info, t, 0);
916 * Force a signal that the process can't ignore: if necessary
917 * we unblock the signal and change any SIG_IGN to SIG_DFL.
919 * Note: If we unblock the signal, we always reset it to SIG_DFL,
920 * since we do not want to have a signal handler that was blocked
921 * be invoked when user space had explicitly blocked it.
923 * We don't want to have recursive SIGSEGV's etc, for example,
924 * that is why we also clear SIGNAL_UNKILLABLE.
927 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
929 unsigned long int flags;
930 int ret, blocked, ignored;
931 struct k_sigaction *action;
933 spin_lock_irqsave(&t->sighand->siglock, flags);
934 action = &t->sighand->action[sig-1];
935 ignored = action->sa.sa_handler == SIG_IGN;
936 blocked = sigismember(&t->blocked, sig);
937 if (blocked || ignored) {
938 action->sa.sa_handler = SIG_DFL;
940 sigdelset(&t->blocked, sig);
941 recalc_sigpending_and_wake(t);
944 if (action->sa.sa_handler == SIG_DFL)
945 t->signal->flags &= ~SIGNAL_UNKILLABLE;
946 ret = specific_send_sig_info(sig, info, t);
947 spin_unlock_irqrestore(&t->sighand->siglock, flags);
953 force_sig_specific(int sig, struct task_struct *t)
955 force_sig_info(sig, SEND_SIG_FORCED, t);
959 * Nuke all other threads in the group.
961 void zap_other_threads(struct task_struct *p)
963 struct task_struct *t;
965 p->signal->group_stop_count = 0;
967 for (t = next_thread(p); t != p; t = next_thread(t)) {
969 * Don't bother with already dead threads
974 /* SIGKILL will be handled before any pending SIGSTOP */
975 sigaddset(&t->pending.signal, SIGKILL);
976 signal_wake_up(t, 1);
980 int __fatal_signal_pending(struct task_struct *tsk)
982 return sigismember(&tsk->pending.signal, SIGKILL);
984 EXPORT_SYMBOL(__fatal_signal_pending);
986 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
988 struct sighand_struct *sighand;
992 sighand = rcu_dereference(tsk->sighand);
993 if (unlikely(sighand == NULL))
996 spin_lock_irqsave(&sighand->siglock, *flags);
997 if (likely(sighand == tsk->sighand))
999 spin_unlock_irqrestore(&sighand->siglock, *flags);
1006 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1008 unsigned long flags;
1011 ret = check_kill_permission(sig, info, p);
1015 if (lock_task_sighand(p, &flags)) {
1016 ret = __group_send_sig_info(sig, info, p);
1017 unlock_task_sighand(p, &flags);
1025 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1026 * control characters do (^C, ^Z etc)
1029 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1031 struct task_struct *p = NULL;
1032 int retval, success;
1036 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1037 int err = group_send_sig_info(sig, info, p);
1040 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1041 return success ? 0 : retval;
1044 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1047 struct task_struct *p;
1051 p = pid_task(pid, PIDTYPE_PID);
1053 error = group_send_sig_info(sig, info, p);
1054 if (unlikely(error == -ESRCH))
1056 * The task was unhashed in between, try again.
1057 * If it is dead, pid_task() will return NULL,
1058 * if we race with de_thread() it will find the
1069 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1073 error = kill_pid_info(sig, info, find_vpid(pid));
1078 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1079 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1080 uid_t uid, uid_t euid, u32 secid)
1083 struct task_struct *p;
1085 if (!valid_signal(sig))
1088 read_lock(&tasklist_lock);
1089 p = pid_task(pid, PIDTYPE_PID);
1094 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1095 && (euid != p->suid) && (euid != p->uid)
1096 && (uid != p->suid) && (uid != p->uid)) {
1100 ret = security_task_kill(p, info, sig, secid);
1103 if (sig && p->sighand) {
1104 unsigned long flags;
1105 spin_lock_irqsave(&p->sighand->siglock, flags);
1106 ret = __group_send_sig_info(sig, info, p);
1107 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1110 read_unlock(&tasklist_lock);
1113 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1116 * kill_something_info() interprets pid in interesting ways just like kill(2).
1118 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1119 * is probably wrong. Should make it like BSD or SYSV.
1122 static int kill_something_info(int sig, struct siginfo *info, int pid)
1128 ret = kill_pid_info(sig, info, find_vpid(pid));
1133 read_lock(&tasklist_lock);
1135 ret = __kill_pgrp_info(sig, info,
1136 pid ? find_vpid(-pid) : task_pgrp(current));
1138 int retval = 0, count = 0;
1139 struct task_struct * p;
1141 for_each_process(p) {
1142 if (p->pid > 1 && !same_thread_group(p, current)) {
1143 int err = group_send_sig_info(sig, info, p);
1149 ret = count ? retval : -ESRCH;
1151 read_unlock(&tasklist_lock);
1157 * These are for backward compatibility with the rest of the kernel source.
1161 * The caller must ensure the task can't exit.
1164 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1167 unsigned long flags;
1170 * Make sure legacy kernel users don't send in bad values
1171 * (normal paths check this in check_kill_permission).
1173 if (!valid_signal(sig))
1176 spin_lock_irqsave(&p->sighand->siglock, flags);
1177 ret = specific_send_sig_info(sig, info, p);
1178 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1182 #define __si_special(priv) \
1183 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1186 send_sig(int sig, struct task_struct *p, int priv)
1188 return send_sig_info(sig, __si_special(priv), p);
1192 force_sig(int sig, struct task_struct *p)
1194 force_sig_info(sig, SEND_SIG_PRIV, p);
1198 * When things go south during signal handling, we
1199 * will force a SIGSEGV. And if the signal that caused
1200 * the problem was already a SIGSEGV, we'll want to
1201 * make sure we don't even try to deliver the signal..
1204 force_sigsegv(int sig, struct task_struct *p)
1206 if (sig == SIGSEGV) {
1207 unsigned long flags;
1208 spin_lock_irqsave(&p->sighand->siglock, flags);
1209 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1210 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1212 force_sig(SIGSEGV, p);
1216 int kill_pgrp(struct pid *pid, int sig, int priv)
1220 read_lock(&tasklist_lock);
1221 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1222 read_unlock(&tasklist_lock);
1226 EXPORT_SYMBOL(kill_pgrp);
1228 int kill_pid(struct pid *pid, int sig, int priv)
1230 return kill_pid_info(sig, __si_special(priv), pid);
1232 EXPORT_SYMBOL(kill_pid);
1235 kill_proc(pid_t pid, int sig, int priv)
1240 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1246 * These functions support sending signals using preallocated sigqueue
1247 * structures. This is needed "because realtime applications cannot
1248 * afford to lose notifications of asynchronous events, like timer
1249 * expirations or I/O completions". In the case of Posix Timers
1250 * we allocate the sigqueue structure from the timer_create. If this
1251 * allocation fails we are able to report the failure to the application
1252 * with an EAGAIN error.
1255 struct sigqueue *sigqueue_alloc(void)
1259 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1260 q->flags |= SIGQUEUE_PREALLOC;
1264 void sigqueue_free(struct sigqueue *q)
1266 unsigned long flags;
1267 spinlock_t *lock = ¤t->sighand->siglock;
1269 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1271 * We must hold ->siglock while testing q->list
1272 * to serialize with collect_signal() or with
1273 * __exit_signal()->flush_sigqueue().
1275 spin_lock_irqsave(lock, flags);
1276 q->flags &= ~SIGQUEUE_PREALLOC;
1278 * If it is queued it will be freed when dequeued,
1279 * like the "regular" sigqueue.
1281 if (!list_empty(&q->list))
1283 spin_unlock_irqrestore(lock, flags);
1289 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1291 int sig = q->info.si_signo;
1292 struct sigpending *pending;
1293 unsigned long flags;
1296 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1299 if (!likely(lock_task_sighand(t, &flags)))
1302 ret = 1; /* the signal is ignored */
1303 if (!prepare_signal(sig, t))
1307 if (unlikely(!list_empty(&q->list))) {
1309 * If an SI_TIMER entry is already queue just increment
1310 * the overrun count.
1312 BUG_ON(q->info.si_code != SI_TIMER);
1313 q->info.si_overrun++;
1317 signalfd_notify(t, sig);
1318 pending = group ? &t->signal->shared_pending : &t->pending;
1319 list_add_tail(&q->list, &pending->list);
1320 sigaddset(&pending->signal, sig);
1321 complete_signal(sig, t, group);
1323 unlock_task_sighand(t, &flags);
1329 * Wake up any threads in the parent blocked in wait* syscalls.
1331 static inline void __wake_up_parent(struct task_struct *p,
1332 struct task_struct *parent)
1334 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1338 * Let a parent know about the death of a child.
1339 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1342 void do_notify_parent(struct task_struct *tsk, int sig)
1344 struct siginfo info;
1345 unsigned long flags;
1346 struct sighand_struct *psig;
1350 /* do_notify_parent_cldstop should have been called instead. */
1351 BUG_ON(task_is_stopped_or_traced(tsk));
1353 BUG_ON(!tsk->ptrace &&
1354 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1356 info.si_signo = sig;
1359 * we are under tasklist_lock here so our parent is tied to
1360 * us and cannot exit and release its namespace.
1362 * the only it can is to switch its nsproxy with sys_unshare,
1363 * bu uncharing pid namespaces is not allowed, so we'll always
1364 * see relevant namespace
1366 * write_lock() currently calls preempt_disable() which is the
1367 * same as rcu_read_lock(), but according to Oleg, this is not
1368 * correct to rely on this
1371 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1374 info.si_uid = tsk->uid;
1376 /* FIXME: find out whether or not this is supposed to be c*time. */
1377 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1378 tsk->signal->utime));
1379 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1380 tsk->signal->stime));
1382 info.si_status = tsk->exit_code & 0x7f;
1383 if (tsk->exit_code & 0x80)
1384 info.si_code = CLD_DUMPED;
1385 else if (tsk->exit_code & 0x7f)
1386 info.si_code = CLD_KILLED;
1388 info.si_code = CLD_EXITED;
1389 info.si_status = tsk->exit_code >> 8;
1392 psig = tsk->parent->sighand;
1393 spin_lock_irqsave(&psig->siglock, flags);
1394 if (!tsk->ptrace && sig == SIGCHLD &&
1395 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1396 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1398 * We are exiting and our parent doesn't care. POSIX.1
1399 * defines special semantics for setting SIGCHLD to SIG_IGN
1400 * or setting the SA_NOCLDWAIT flag: we should be reaped
1401 * automatically and not left for our parent's wait4 call.
1402 * Rather than having the parent do it as a magic kind of
1403 * signal handler, we just set this to tell do_exit that we
1404 * can be cleaned up without becoming a zombie. Note that
1405 * we still call __wake_up_parent in this case, because a
1406 * blocked sys_wait4 might now return -ECHILD.
1408 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1409 * is implementation-defined: we do (if you don't want
1410 * it, just use SIG_IGN instead).
1412 tsk->exit_signal = -1;
1413 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1416 if (valid_signal(sig) && sig > 0)
1417 __group_send_sig_info(sig, &info, tsk->parent);
1418 __wake_up_parent(tsk, tsk->parent);
1419 spin_unlock_irqrestore(&psig->siglock, flags);
1422 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1424 struct siginfo info;
1425 unsigned long flags;
1426 struct task_struct *parent;
1427 struct sighand_struct *sighand;
1429 if (tsk->ptrace & PT_PTRACED)
1430 parent = tsk->parent;
1432 tsk = tsk->group_leader;
1433 parent = tsk->real_parent;
1436 info.si_signo = SIGCHLD;
1439 * see comment in do_notify_parent() abot the following 3 lines
1442 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1445 info.si_uid = tsk->uid;
1447 /* FIXME: find out whether or not this is supposed to be c*time. */
1448 info.si_utime = cputime_to_jiffies(tsk->utime);
1449 info.si_stime = cputime_to_jiffies(tsk->stime);
1454 info.si_status = SIGCONT;
1457 info.si_status = tsk->signal->group_exit_code & 0x7f;
1460 info.si_status = tsk->exit_code & 0x7f;
1466 sighand = parent->sighand;
1467 spin_lock_irqsave(&sighand->siglock, flags);
1468 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1469 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1470 __group_send_sig_info(SIGCHLD, &info, parent);
1472 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1474 __wake_up_parent(tsk, parent);
1475 spin_unlock_irqrestore(&sighand->siglock, flags);
1478 static inline int may_ptrace_stop(void)
1480 if (!likely(current->ptrace & PT_PTRACED))
1483 * Are we in the middle of do_coredump?
1484 * If so and our tracer is also part of the coredump stopping
1485 * is a deadlock situation, and pointless because our tracer
1486 * is dead so don't allow us to stop.
1487 * If SIGKILL was already sent before the caller unlocked
1488 * ->siglock we must see ->core_waiters != 0. Otherwise it
1489 * is safe to enter schedule().
1491 if (unlikely(current->mm->core_waiters) &&
1492 unlikely(current->mm == current->parent->mm))
1499 * Return nonzero if there is a SIGKILL that should be waking us up.
1500 * Called with the siglock held.
1502 static int sigkill_pending(struct task_struct *tsk)
1504 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1505 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1506 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1510 * This must be called with current->sighand->siglock held.
1512 * This should be the path for all ptrace stops.
1513 * We always set current->last_siginfo while stopped here.
1514 * That makes it a way to test a stopped process for
1515 * being ptrace-stopped vs being job-control-stopped.
1517 * If we actually decide not to stop at all because the tracer
1518 * is gone, we keep current->exit_code unless clear_code.
1520 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1524 if (arch_ptrace_stop_needed(exit_code, info)) {
1526 * The arch code has something special to do before a
1527 * ptrace stop. This is allowed to block, e.g. for faults
1528 * on user stack pages. We can't keep the siglock while
1529 * calling arch_ptrace_stop, so we must release it now.
1530 * To preserve proper semantics, we must do this before
1531 * any signal bookkeeping like checking group_stop_count.
1532 * Meanwhile, a SIGKILL could come in before we retake the
1533 * siglock. That must prevent us from sleeping in TASK_TRACED.
1534 * So after regaining the lock, we must check for SIGKILL.
1536 spin_unlock_irq(¤t->sighand->siglock);
1537 arch_ptrace_stop(exit_code, info);
1538 spin_lock_irq(¤t->sighand->siglock);
1539 killed = sigkill_pending(current);
1543 * If there is a group stop in progress,
1544 * we must participate in the bookkeeping.
1546 if (current->signal->group_stop_count > 0)
1547 --current->signal->group_stop_count;
1549 current->last_siginfo = info;
1550 current->exit_code = exit_code;
1552 /* Let the debugger run. */
1553 __set_current_state(TASK_TRACED);
1554 spin_unlock_irq(¤t->sighand->siglock);
1555 read_lock(&tasklist_lock);
1556 if (!unlikely(killed) && may_ptrace_stop()) {
1557 do_notify_parent_cldstop(current, CLD_TRAPPED);
1558 read_unlock(&tasklist_lock);
1562 * By the time we got the lock, our tracer went away.
1563 * Don't drop the lock yet, another tracer may come.
1565 __set_current_state(TASK_RUNNING);
1567 current->exit_code = 0;
1568 read_unlock(&tasklist_lock);
1572 * While in TASK_TRACED, we were considered "frozen enough".
1573 * Now that we woke up, it's crucial if we're supposed to be
1574 * frozen that we freeze now before running anything substantial.
1579 * We are back. Now reacquire the siglock before touching
1580 * last_siginfo, so that we are sure to have synchronized with
1581 * any signal-sending on another CPU that wants to examine it.
1583 spin_lock_irq(¤t->sighand->siglock);
1584 current->last_siginfo = NULL;
1587 * Queued signals ignored us while we were stopped for tracing.
1588 * So check for any that we should take before resuming user mode.
1589 * This sets TIF_SIGPENDING, but never clears it.
1591 recalc_sigpending_tsk(current);
1594 void ptrace_notify(int exit_code)
1598 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1600 memset(&info, 0, sizeof info);
1601 info.si_signo = SIGTRAP;
1602 info.si_code = exit_code;
1603 info.si_pid = task_pid_vnr(current);
1604 info.si_uid = current->uid;
1606 /* Let the debugger run. */
1607 spin_lock_irq(¤t->sighand->siglock);
1608 ptrace_stop(exit_code, 1, &info);
1609 spin_unlock_irq(¤t->sighand->siglock);
1613 finish_stop(int stop_count)
1616 * If there are no other threads in the group, or if there is
1617 * a group stop in progress and we are the last to stop,
1618 * report to the parent. When ptraced, every thread reports itself.
1620 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1621 read_lock(&tasklist_lock);
1622 do_notify_parent_cldstop(current, CLD_STOPPED);
1623 read_unlock(&tasklist_lock);
1628 } while (try_to_freeze());
1630 * Now we don't run again until continued.
1632 current->exit_code = 0;
1636 * This performs the stopping for SIGSTOP and other stop signals.
1637 * We have to stop all threads in the thread group.
1638 * Returns nonzero if we've actually stopped and released the siglock.
1639 * Returns zero if we didn't stop and still hold the siglock.
1641 static int do_signal_stop(int signr)
1643 struct signal_struct *sig = current->signal;
1646 if (sig->group_stop_count > 0) {
1648 * There is a group stop in progress. We don't need to
1649 * start another one.
1651 stop_count = --sig->group_stop_count;
1653 struct task_struct *t;
1655 if (unlikely((sig->flags & (SIGNAL_STOP_DEQUEUED | SIGNAL_UNKILLABLE))
1656 != SIGNAL_STOP_DEQUEUED) ||
1657 unlikely(signal_group_exit(sig)))
1660 * There is no group stop already in progress.
1661 * We must initiate one now.
1663 sig->group_exit_code = signr;
1666 for (t = next_thread(current); t != current; t = next_thread(t))
1668 * Setting state to TASK_STOPPED for a group
1669 * stop is always done with the siglock held,
1670 * so this check has no races.
1672 if (!(t->flags & PF_EXITING) &&
1673 !task_is_stopped_or_traced(t)) {
1675 signal_wake_up(t, 0);
1677 sig->group_stop_count = stop_count;
1680 if (stop_count == 0)
1681 sig->flags = SIGNAL_STOP_STOPPED;
1682 current->exit_code = sig->group_exit_code;
1683 __set_current_state(TASK_STOPPED);
1685 spin_unlock_irq(¤t->sighand->siglock);
1686 finish_stop(stop_count);
1690 static int ptrace_signal(int signr, siginfo_t *info,
1691 struct pt_regs *regs, void *cookie)
1693 if (!(current->ptrace & PT_PTRACED))
1696 ptrace_signal_deliver(regs, cookie);
1698 /* Let the debugger run. */
1699 ptrace_stop(signr, 0, info);
1701 /* We're back. Did the debugger cancel the sig? */
1702 signr = current->exit_code;
1706 current->exit_code = 0;
1708 /* Update the siginfo structure if the signal has
1709 changed. If the debugger wanted something
1710 specific in the siginfo structure then it should
1711 have updated *info via PTRACE_SETSIGINFO. */
1712 if (signr != info->si_signo) {
1713 info->si_signo = signr;
1715 info->si_code = SI_USER;
1716 info->si_pid = task_pid_vnr(current->parent);
1717 info->si_uid = current->parent->uid;
1720 /* If the (new) signal is now blocked, requeue it. */
1721 if (sigismember(¤t->blocked, signr)) {
1722 specific_send_sig_info(signr, info, current);
1729 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1730 struct pt_regs *regs, void *cookie)
1732 struct sighand_struct *sighand = current->sighand;
1733 struct signal_struct *signal = current->signal;
1738 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1739 * While in TASK_STOPPED, we were considered "frozen enough".
1740 * Now that we woke up, it's crucial if we're supposed to be
1741 * frozen that we freeze now before running anything substantial.
1745 spin_lock_irq(&sighand->siglock);
1747 * Every stopped thread goes here after wakeup. Check to see if
1748 * we should notify the parent, prepare_signal(SIGCONT) encodes
1749 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1751 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1752 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1753 ? CLD_CONTINUED : CLD_STOPPED;
1754 signal->flags &= ~SIGNAL_CLD_MASK;
1755 spin_unlock_irq(&sighand->siglock);
1757 read_lock(&tasklist_lock);
1758 do_notify_parent_cldstop(current->group_leader, why);
1759 read_unlock(&tasklist_lock);
1764 struct k_sigaction *ka;
1766 if (unlikely(signal->group_stop_count > 0) &&
1770 signr = dequeue_signal(current, ¤t->blocked, info);
1772 break; /* will return 0 */
1774 if (signr != SIGKILL) {
1775 signr = ptrace_signal(signr, info, regs, cookie);
1780 ka = &sighand->action[signr-1];
1781 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1783 if (ka->sa.sa_handler != SIG_DFL) {
1784 /* Run the handler. */
1787 if (ka->sa.sa_flags & SA_ONESHOT)
1788 ka->sa.sa_handler = SIG_DFL;
1790 break; /* will return non-zero "signr" value */
1794 * Now we are doing the default action for this signal.
1796 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1800 * Global init gets no signals it doesn't want.
1802 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1803 !signal_group_exit(signal))
1806 if (sig_kernel_stop(signr)) {
1808 * The default action is to stop all threads in
1809 * the thread group. The job control signals
1810 * do nothing in an orphaned pgrp, but SIGSTOP
1811 * always works. Note that siglock needs to be
1812 * dropped during the call to is_orphaned_pgrp()
1813 * because of lock ordering with tasklist_lock.
1814 * This allows an intervening SIGCONT to be posted.
1815 * We need to check for that and bail out if necessary.
1817 if (signr != SIGSTOP) {
1818 spin_unlock_irq(&sighand->siglock);
1820 /* signals can be posted during this window */
1822 if (is_current_pgrp_orphaned())
1825 spin_lock_irq(&sighand->siglock);
1828 if (likely(do_signal_stop(signr))) {
1829 /* It released the siglock. */
1834 * We didn't actually stop, due to a race
1835 * with SIGCONT or something like that.
1840 spin_unlock_irq(&sighand->siglock);
1843 * Anything else is fatal, maybe with a core dump.
1845 current->flags |= PF_SIGNALED;
1847 if (sig_kernel_coredump(signr)) {
1848 if (print_fatal_signals)
1849 print_fatal_signal(regs, signr);
1851 * If it was able to dump core, this kills all
1852 * other threads in the group and synchronizes with
1853 * their demise. If we lost the race with another
1854 * thread getting here, it set group_exit_code
1855 * first and our do_group_exit call below will use
1856 * that value and ignore the one we pass it.
1858 do_coredump((long)signr, signr, regs);
1862 * Death signals, no core dump.
1864 do_group_exit(signr);
1867 spin_unlock_irq(&sighand->siglock);
1871 void exit_signals(struct task_struct *tsk)
1874 struct task_struct *t;
1876 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1877 tsk->flags |= PF_EXITING;
1881 spin_lock_irq(&tsk->sighand->siglock);
1883 * From now this task is not visible for group-wide signals,
1884 * see wants_signal(), do_signal_stop().
1886 tsk->flags |= PF_EXITING;
1887 if (!signal_pending(tsk))
1890 /* It could be that __group_complete_signal() choose us to
1891 * notify about group-wide signal. Another thread should be
1892 * woken now to take the signal since we will not.
1894 for (t = tsk; (t = next_thread(t)) != tsk; )
1895 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1896 recalc_sigpending_and_wake(t);
1898 if (unlikely(tsk->signal->group_stop_count) &&
1899 !--tsk->signal->group_stop_count) {
1900 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1904 spin_unlock_irq(&tsk->sighand->siglock);
1906 if (unlikely(group_stop)) {
1907 read_lock(&tasklist_lock);
1908 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1909 read_unlock(&tasklist_lock);
1913 EXPORT_SYMBOL(recalc_sigpending);
1914 EXPORT_SYMBOL_GPL(dequeue_signal);
1915 EXPORT_SYMBOL(flush_signals);
1916 EXPORT_SYMBOL(force_sig);
1917 EXPORT_SYMBOL(kill_proc);
1918 EXPORT_SYMBOL(ptrace_notify);
1919 EXPORT_SYMBOL(send_sig);
1920 EXPORT_SYMBOL(send_sig_info);
1921 EXPORT_SYMBOL(sigprocmask);
1922 EXPORT_SYMBOL(block_all_signals);
1923 EXPORT_SYMBOL(unblock_all_signals);
1927 * System call entry points.
1930 asmlinkage long sys_restart_syscall(void)
1932 struct restart_block *restart = ¤t_thread_info()->restart_block;
1933 return restart->fn(restart);
1936 long do_no_restart_syscall(struct restart_block *param)
1942 * We don't need to get the kernel lock - this is all local to this
1943 * particular thread.. (and that's good, because this is _heavily_
1944 * used by various programs)
1948 * This is also useful for kernel threads that want to temporarily
1949 * (or permanently) block certain signals.
1951 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1952 * interface happily blocks "unblockable" signals like SIGKILL
1955 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1959 spin_lock_irq(¤t->sighand->siglock);
1961 *oldset = current->blocked;
1966 sigorsets(¤t->blocked, ¤t->blocked, set);
1969 signandsets(¤t->blocked, ¤t->blocked, set);
1972 current->blocked = *set;
1977 recalc_sigpending();
1978 spin_unlock_irq(¤t->sighand->siglock);
1984 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1986 int error = -EINVAL;
1987 sigset_t old_set, new_set;
1989 /* XXX: Don't preclude handling different sized sigset_t's. */
1990 if (sigsetsize != sizeof(sigset_t))
1995 if (copy_from_user(&new_set, set, sizeof(*set)))
1997 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1999 error = sigprocmask(how, &new_set, &old_set);
2005 spin_lock_irq(¤t->sighand->siglock);
2006 old_set = current->blocked;
2007 spin_unlock_irq(¤t->sighand->siglock);
2011 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2019 long do_sigpending(void __user *set, unsigned long sigsetsize)
2021 long error = -EINVAL;
2024 if (sigsetsize > sizeof(sigset_t))
2027 spin_lock_irq(¤t->sighand->siglock);
2028 sigorsets(&pending, ¤t->pending.signal,
2029 ¤t->signal->shared_pending.signal);
2030 spin_unlock_irq(¤t->sighand->siglock);
2032 /* Outside the lock because only this thread touches it. */
2033 sigandsets(&pending, ¤t->blocked, &pending);
2036 if (!copy_to_user(set, &pending, sigsetsize))
2044 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2046 return do_sigpending(set, sigsetsize);
2049 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2051 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2055 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2057 if (from->si_code < 0)
2058 return __copy_to_user(to, from, sizeof(siginfo_t))
2061 * If you change siginfo_t structure, please be sure
2062 * this code is fixed accordingly.
2063 * Please remember to update the signalfd_copyinfo() function
2064 * inside fs/signalfd.c too, in case siginfo_t changes.
2065 * It should never copy any pad contained in the structure
2066 * to avoid security leaks, but must copy the generic
2067 * 3 ints plus the relevant union member.
2069 err = __put_user(from->si_signo, &to->si_signo);
2070 err |= __put_user(from->si_errno, &to->si_errno);
2071 err |= __put_user((short)from->si_code, &to->si_code);
2072 switch (from->si_code & __SI_MASK) {
2074 err |= __put_user(from->si_pid, &to->si_pid);
2075 err |= __put_user(from->si_uid, &to->si_uid);
2078 err |= __put_user(from->si_tid, &to->si_tid);
2079 err |= __put_user(from->si_overrun, &to->si_overrun);
2080 err |= __put_user(from->si_ptr, &to->si_ptr);
2083 err |= __put_user(from->si_band, &to->si_band);
2084 err |= __put_user(from->si_fd, &to->si_fd);
2087 err |= __put_user(from->si_addr, &to->si_addr);
2088 #ifdef __ARCH_SI_TRAPNO
2089 err |= __put_user(from->si_trapno, &to->si_trapno);
2093 err |= __put_user(from->si_pid, &to->si_pid);
2094 err |= __put_user(from->si_uid, &to->si_uid);
2095 err |= __put_user(from->si_status, &to->si_status);
2096 err |= __put_user(from->si_utime, &to->si_utime);
2097 err |= __put_user(from->si_stime, &to->si_stime);
2099 case __SI_RT: /* This is not generated by the kernel as of now. */
2100 case __SI_MESGQ: /* But this is */
2101 err |= __put_user(from->si_pid, &to->si_pid);
2102 err |= __put_user(from->si_uid, &to->si_uid);
2103 err |= __put_user(from->si_ptr, &to->si_ptr);
2105 default: /* this is just in case for now ... */
2106 err |= __put_user(from->si_pid, &to->si_pid);
2107 err |= __put_user(from->si_uid, &to->si_uid);
2116 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2117 siginfo_t __user *uinfo,
2118 const struct timespec __user *uts,
2127 /* XXX: Don't preclude handling different sized sigset_t's. */
2128 if (sigsetsize != sizeof(sigset_t))
2131 if (copy_from_user(&these, uthese, sizeof(these)))
2135 * Invert the set of allowed signals to get those we
2138 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2142 if (copy_from_user(&ts, uts, sizeof(ts)))
2144 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2149 spin_lock_irq(¤t->sighand->siglock);
2150 sig = dequeue_signal(current, &these, &info);
2152 timeout = MAX_SCHEDULE_TIMEOUT;
2154 timeout = (timespec_to_jiffies(&ts)
2155 + (ts.tv_sec || ts.tv_nsec));
2158 /* None ready -- temporarily unblock those we're
2159 * interested while we are sleeping in so that we'll
2160 * be awakened when they arrive. */
2161 current->real_blocked = current->blocked;
2162 sigandsets(¤t->blocked, ¤t->blocked, &these);
2163 recalc_sigpending();
2164 spin_unlock_irq(¤t->sighand->siglock);
2166 timeout = schedule_timeout_interruptible(timeout);
2168 spin_lock_irq(¤t->sighand->siglock);
2169 sig = dequeue_signal(current, &these, &info);
2170 current->blocked = current->real_blocked;
2171 siginitset(¤t->real_blocked, 0);
2172 recalc_sigpending();
2175 spin_unlock_irq(¤t->sighand->siglock);
2180 if (copy_siginfo_to_user(uinfo, &info))
2193 sys_kill(int pid, int sig)
2195 struct siginfo info;
2197 info.si_signo = sig;
2199 info.si_code = SI_USER;
2200 info.si_pid = task_tgid_vnr(current);
2201 info.si_uid = current->uid;
2203 return kill_something_info(sig, &info, pid);
2206 static int do_tkill(int tgid, int pid, int sig)
2209 struct siginfo info;
2210 struct task_struct *p;
2211 unsigned long flags;
2214 info.si_signo = sig;
2216 info.si_code = SI_TKILL;
2217 info.si_pid = task_tgid_vnr(current);
2218 info.si_uid = current->uid;
2221 p = find_task_by_vpid(pid);
2222 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2223 error = check_kill_permission(sig, &info, p);
2225 * The null signal is a permissions and process existence
2226 * probe. No signal is actually delivered.
2228 * If lock_task_sighand() fails we pretend the task dies
2229 * after receiving the signal. The window is tiny, and the
2230 * signal is private anyway.
2232 if (!error && sig && lock_task_sighand(p, &flags)) {
2233 error = specific_send_sig_info(sig, &info, p);
2234 unlock_task_sighand(p, &flags);
2243 * sys_tgkill - send signal to one specific thread
2244 * @tgid: the thread group ID of the thread
2245 * @pid: the PID of the thread
2246 * @sig: signal to be sent
2248 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2249 * exists but it's not belonging to the target process anymore. This
2250 * method solves the problem of threads exiting and PIDs getting reused.
2252 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2254 /* This is only valid for single tasks */
2255 if (pid <= 0 || tgid <= 0)
2258 return do_tkill(tgid, pid, sig);
2262 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2265 sys_tkill(int pid, int sig)
2267 /* This is only valid for single tasks */
2271 return do_tkill(0, pid, sig);
2275 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2279 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2282 /* Not even root can pretend to send signals from the kernel.
2283 Nor can they impersonate a kill(), which adds source info. */
2284 if (info.si_code >= 0)
2286 info.si_signo = sig;
2288 /* POSIX.1b doesn't mention process groups. */
2289 return kill_proc_info(sig, &info, pid);
2292 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2294 struct task_struct *t = current;
2295 struct k_sigaction *k;
2298 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2301 k = &t->sighand->action[sig-1];
2303 spin_lock_irq(¤t->sighand->siglock);
2308 sigdelsetmask(&act->sa.sa_mask,
2309 sigmask(SIGKILL) | sigmask(SIGSTOP));
2313 * "Setting a signal action to SIG_IGN for a signal that is
2314 * pending shall cause the pending signal to be discarded,
2315 * whether or not it is blocked."
2317 * "Setting a signal action to SIG_DFL for a signal that is
2318 * pending and whose default action is to ignore the signal
2319 * (for example, SIGCHLD), shall cause the pending signal to
2320 * be discarded, whether or not it is blocked"
2322 if (__sig_ignored(t, sig)) {
2324 sigaddset(&mask, sig);
2325 rm_from_queue_full(&mask, &t->signal->shared_pending);
2327 rm_from_queue_full(&mask, &t->pending);
2329 } while (t != current);
2333 spin_unlock_irq(¤t->sighand->siglock);
2338 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2344 oss.ss_sp = (void __user *) current->sas_ss_sp;
2345 oss.ss_size = current->sas_ss_size;
2346 oss.ss_flags = sas_ss_flags(sp);
2355 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2356 || __get_user(ss_sp, &uss->ss_sp)
2357 || __get_user(ss_flags, &uss->ss_flags)
2358 || __get_user(ss_size, &uss->ss_size))
2362 if (on_sig_stack(sp))
2368 * Note - this code used to test ss_flags incorrectly
2369 * old code may have been written using ss_flags==0
2370 * to mean ss_flags==SS_ONSTACK (as this was the only
2371 * way that worked) - this fix preserves that older
2374 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2377 if (ss_flags == SS_DISABLE) {
2382 if (ss_size < MINSIGSTKSZ)
2386 current->sas_ss_sp = (unsigned long) ss_sp;
2387 current->sas_ss_size = ss_size;
2392 if (copy_to_user(uoss, &oss, sizeof(oss)))
2401 #ifdef __ARCH_WANT_SYS_SIGPENDING
2404 sys_sigpending(old_sigset_t __user *set)
2406 return do_sigpending(set, sizeof(*set));
2411 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2412 /* Some platforms have their own version with special arguments others
2413 support only sys_rt_sigprocmask. */
2416 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2419 old_sigset_t old_set, new_set;
2423 if (copy_from_user(&new_set, set, sizeof(*set)))
2425 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2427 spin_lock_irq(¤t->sighand->siglock);
2428 old_set = current->blocked.sig[0];
2436 sigaddsetmask(¤t->blocked, new_set);
2439 sigdelsetmask(¤t->blocked, new_set);
2442 current->blocked.sig[0] = new_set;
2446 recalc_sigpending();
2447 spin_unlock_irq(¤t->sighand->siglock);
2453 old_set = current->blocked.sig[0];
2456 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2463 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2465 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2467 sys_rt_sigaction(int sig,
2468 const struct sigaction __user *act,
2469 struct sigaction __user *oact,
2472 struct k_sigaction new_sa, old_sa;
2475 /* XXX: Don't preclude handling different sized sigset_t's. */
2476 if (sigsetsize != sizeof(sigset_t))
2480 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2484 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2487 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2493 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2495 #ifdef __ARCH_WANT_SYS_SGETMASK
2498 * For backwards compatibility. Functionality superseded by sigprocmask.
2504 return current->blocked.sig[0];
2508 sys_ssetmask(int newmask)
2512 spin_lock_irq(¤t->sighand->siglock);
2513 old = current->blocked.sig[0];
2515 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2517 recalc_sigpending();
2518 spin_unlock_irq(¤t->sighand->siglock);
2522 #endif /* __ARCH_WANT_SGETMASK */
2524 #ifdef __ARCH_WANT_SYS_SIGNAL
2526 * For backwards compatibility. Functionality superseded by sigaction.
2528 asmlinkage unsigned long
2529 sys_signal(int sig, __sighandler_t handler)
2531 struct k_sigaction new_sa, old_sa;
2534 new_sa.sa.sa_handler = handler;
2535 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2536 sigemptyset(&new_sa.sa.sa_mask);
2538 ret = do_sigaction(sig, &new_sa, &old_sa);
2540 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2542 #endif /* __ARCH_WANT_SYS_SIGNAL */
2544 #ifdef __ARCH_WANT_SYS_PAUSE
2549 current->state = TASK_INTERRUPTIBLE;
2551 return -ERESTARTNOHAND;
2556 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2557 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2561 /* XXX: Don't preclude handling different sized sigset_t's. */
2562 if (sigsetsize != sizeof(sigset_t))
2565 if (copy_from_user(&newset, unewset, sizeof(newset)))
2567 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2569 spin_lock_irq(¤t->sighand->siglock);
2570 current->saved_sigmask = current->blocked;
2571 current->blocked = newset;
2572 recalc_sigpending();
2573 spin_unlock_irq(¤t->sighand->siglock);
2575 current->state = TASK_INTERRUPTIBLE;
2577 set_restore_sigmask();
2578 return -ERESTARTNOHAND;
2580 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2582 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2587 void __init signals_init(void)
2589 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);