2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache *sigqueue_cachep;
42 static int __sig_ignored(struct task_struct *t, int sig)
46 /* Is it explicitly or implicitly ignored? */
48 handler = t->sighand->action[sig - 1].sa.sa_handler;
49 return handler == SIG_IGN ||
50 (handler == SIG_DFL && sig_kernel_ignore(sig));
53 static int sig_ignored(struct task_struct *t, int sig)
56 * Tracers always want to know about signals..
58 if (t->ptrace & PT_PTRACED)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
69 return __sig_ignored(t, sig);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
81 switch (_NSIG_WORDS) {
83 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
84 ready |= signal->sig[i] &~ blocked->sig[i];
87 case 4: ready = signal->sig[3] &~ blocked->sig[3];
88 ready |= signal->sig[2] &~ blocked->sig[2];
89 ready |= signal->sig[1] &~ blocked->sig[1];
90 ready |= signal->sig[0] &~ blocked->sig[0];
93 case 2: ready = signal->sig[1] &~ blocked->sig[1];
94 ready |= signal->sig[0] &~ blocked->sig[0];
97 case 1: ready = signal->sig[0] &~ blocked->sig[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct *t)
106 if (t->signal->group_stop_count > 0 ||
107 PENDING(&t->pending, &t->blocked) ||
108 PENDING(&t->signal->shared_pending, &t->blocked)) {
109 set_tsk_thread_flag(t, TIF_SIGPENDING);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct *t)
126 if (recalc_sigpending_tsk(t))
127 signal_wake_up(t, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current) && !freezing(current))
133 clear_thread_flag(TIF_SIGPENDING);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending *pending, sigset_t *mask)
141 unsigned long i, *s, *m, x;
144 s = pending->signal.sig;
146 switch (_NSIG_WORDS) {
148 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
149 if ((x = *s &~ *m) != 0) {
150 sig = ffz(~x) + i*_NSIG_BPW + 1;
155 case 2: if ((x = s[0] &~ m[0]) != 0)
157 else if ((x = s[1] &~ m[1]) != 0)
164 case 1: if ((x = *s &~ *m) != 0)
172 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
175 struct sigqueue *q = NULL;
176 struct user_struct *user;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user->sigpending);
185 if (override_rlimit ||
186 atomic_read(&user->sigpending) <=
187 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
188 q = kmem_cache_alloc(sigqueue_cachep, flags);
189 if (unlikely(q == NULL)) {
190 atomic_dec(&user->sigpending);
192 INIT_LIST_HEAD(&q->list);
194 q->user = get_uid(user);
199 static void __sigqueue_free(struct sigqueue *q)
201 if (q->flags & SIGQUEUE_PREALLOC)
203 atomic_dec(&q->user->sigpending);
205 kmem_cache_free(sigqueue_cachep, q);
208 void flush_sigqueue(struct sigpending *queue)
212 sigemptyset(&queue->signal);
213 while (!list_empty(&queue->list)) {
214 q = list_entry(queue->list.next, struct sigqueue , list);
215 list_del_init(&q->list);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct *t)
227 spin_lock_irqsave(&t->sighand->siglock, flags);
228 clear_tsk_thread_flag(t, TIF_SIGPENDING);
229 flush_sigqueue(&t->pending);
230 flush_sigqueue(&t->signal->shared_pending);
231 spin_unlock_irqrestore(&t->sighand->siglock, flags);
234 void ignore_signals(struct task_struct *t)
238 for (i = 0; i < _NSIG; ++i)
239 t->sighand->action[i].sa.sa_handler = SIG_IGN;
245 * Flush all handlers for a task.
249 flush_signal_handlers(struct task_struct *t, int force_default)
252 struct k_sigaction *ka = &t->sighand->action[0];
253 for (i = _NSIG ; i != 0 ; i--) {
254 if (force_default || ka->sa.sa_handler != SIG_IGN)
255 ka->sa.sa_handler = SIG_DFL;
257 sigemptyset(&ka->sa.sa_mask);
262 int unhandled_signal(struct task_struct *tsk, int sig)
264 if (is_global_init(tsk))
266 if (tsk->ptrace & PT_PTRACED)
268 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
269 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
273 /* Notify the system that a driver wants to block all signals for this
274 * process, and wants to be notified if any signals at all were to be
275 * sent/acted upon. If the notifier routine returns non-zero, then the
276 * signal will be acted upon after all. If the notifier routine returns 0,
277 * then then signal will be blocked. Only one block per process is
278 * allowed. priv is a pointer to private data that the notifier routine
279 * can use to determine if the signal should be blocked or not. */
282 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
286 spin_lock_irqsave(¤t->sighand->siglock, flags);
287 current->notifier_mask = mask;
288 current->notifier_data = priv;
289 current->notifier = notifier;
290 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
293 /* Notify the system that blocking has ended. */
296 unblock_all_signals(void)
300 spin_lock_irqsave(¤t->sighand->siglock, flags);
301 current->notifier = NULL;
302 current->notifier_data = NULL;
304 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
307 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
309 struct sigqueue *q, *first = NULL;
310 int still_pending = 0;
312 if (unlikely(!sigismember(&list->signal, sig)))
316 * Collect the siginfo appropriate to this signal. Check if
317 * there is another siginfo for the same signal.
319 list_for_each_entry(q, &list->list, list) {
320 if (q->info.si_signo == sig) {
329 list_del_init(&first->list);
330 copy_siginfo(info, &first->info);
331 __sigqueue_free(first);
333 sigdelset(&list->signal, sig);
336 /* Ok, it wasn't in the queue. This must be
337 a fast-pathed signal or we must have been
338 out of queue space. So zero out the info.
340 sigdelset(&list->signal, sig);
341 info->si_signo = sig;
350 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
353 int sig = next_signal(pending, mask);
356 if (current->notifier) {
357 if (sigismember(current->notifier_mask, sig)) {
358 if (!(current->notifier)(current->notifier_data)) {
359 clear_thread_flag(TIF_SIGPENDING);
365 if (!collect_signal(sig, pending, info))
373 * Dequeue a signal and return the element to the caller, which is
374 * expected to free it.
376 * All callers have to hold the siglock.
378 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
382 /* We only dequeue private signals from ourselves, we don't let
383 * signalfd steal them
385 signr = __dequeue_signal(&tsk->pending, mask, info);
387 signr = __dequeue_signal(&tsk->signal->shared_pending,
392 * itimers are process shared and we restart periodic
393 * itimers in the signal delivery path to prevent DoS
394 * attacks in the high resolution timer case. This is
395 * compliant with the old way of self restarting
396 * itimers, as the SIGALRM is a legacy signal and only
397 * queued once. Changing the restart behaviour to
398 * restart the timer in the signal dequeue path is
399 * reducing the timer noise on heavy loaded !highres
402 if (unlikely(signr == SIGALRM)) {
403 struct hrtimer *tmr = &tsk->signal->real_timer;
405 if (!hrtimer_is_queued(tmr) &&
406 tsk->signal->it_real_incr.tv64 != 0) {
407 hrtimer_forward(tmr, tmr->base->get_time(),
408 tsk->signal->it_real_incr);
409 hrtimer_restart(tmr);
418 if (unlikely(sig_kernel_stop(signr))) {
420 * Set a marker that we have dequeued a stop signal. Our
421 * caller might release the siglock and then the pending
422 * stop signal it is about to process is no longer in the
423 * pending bitmasks, but must still be cleared by a SIGCONT
424 * (and overruled by a SIGKILL). So those cases clear this
425 * shared flag after we've set it. Note that this flag may
426 * remain set after the signal we return is ignored or
427 * handled. That doesn't matter because its only purpose
428 * is to alert stop-signal processing code when another
429 * processor has come along and cleared the flag.
431 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
432 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
434 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
436 * Release the siglock to ensure proper locking order
437 * of timer locks outside of siglocks. Note, we leave
438 * irqs disabled here, since the posix-timers code is
439 * about to disable them again anyway.
441 spin_unlock(&tsk->sighand->siglock);
442 do_schedule_next_timer(info);
443 spin_lock(&tsk->sighand->siglock);
449 * Tell a process that it has a new active signal..
451 * NOTE! we rely on the previous spin_lock to
452 * lock interrupts for us! We can only be called with
453 * "siglock" held, and the local interrupt must
454 * have been disabled when that got acquired!
456 * No need to set need_resched since signal event passing
457 * goes through ->blocked
459 void signal_wake_up(struct task_struct *t, int resume)
463 set_tsk_thread_flag(t, TIF_SIGPENDING);
466 * For SIGKILL, we want to wake it up in the stopped/traced/killable
467 * case. We don't check t->state here because there is a race with it
468 * executing another processor and just now entering stopped state.
469 * By using wake_up_state, we ensure the process will wake up and
470 * handle its death signal.
472 mask = TASK_INTERRUPTIBLE;
474 mask |= TASK_WAKEKILL;
475 if (!wake_up_state(t, mask))
480 * Remove signals in mask from the pending set and queue.
481 * Returns 1 if any signals were found.
483 * All callers must be holding the siglock.
485 * This version takes a sigset mask and looks at all signals,
486 * not just those in the first mask word.
488 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
490 struct sigqueue *q, *n;
493 sigandsets(&m, mask, &s->signal);
494 if (sigisemptyset(&m))
497 signandsets(&s->signal, &s->signal, mask);
498 list_for_each_entry_safe(q, n, &s->list, list) {
499 if (sigismember(mask, q->info.si_signo)) {
500 list_del_init(&q->list);
507 * Remove signals in mask from the pending set and queue.
508 * Returns 1 if any signals were found.
510 * All callers must be holding the siglock.
512 static int rm_from_queue(unsigned long mask, struct sigpending *s)
514 struct sigqueue *q, *n;
516 if (!sigtestsetmask(&s->signal, mask))
519 sigdelsetmask(&s->signal, mask);
520 list_for_each_entry_safe(q, n, &s->list, list) {
521 if (q->info.si_signo < SIGRTMIN &&
522 (mask & sigmask(q->info.si_signo))) {
523 list_del_init(&q->list);
531 * Bad permissions for sending the signal
533 static int check_kill_permission(int sig, struct siginfo *info,
534 struct task_struct *t)
538 if (!valid_signal(sig))
541 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
544 error = audit_signal_info(sig, t); /* Let audit system see the signal */
548 if (((sig != SIGCONT) || (task_session_nr(current) != task_session_nr(t)))
549 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
550 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
551 && !capable(CAP_KILL))
554 return security_task_kill(t, info, sig, 0);
558 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
561 * Handle magic process-wide effects of stop/continue signals. Unlike
562 * the signal actions, these happen immediately at signal-generation
563 * time regardless of blocking, ignoring, or handling. This does the
564 * actual continuing for SIGCONT, but not the actual stopping for stop
565 * signals. The process stop is done as a signal action for SIG_DFL.
567 * Returns true if the signal should be actually delivered, otherwise
568 * it should be dropped.
570 static int prepare_signal(int sig, struct task_struct *p)
572 struct signal_struct *signal = p->signal;
573 struct task_struct *t;
575 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
577 * The process is in the middle of dying, nothing to do.
579 } else if (sig_kernel_stop(sig)) {
581 * This is a stop signal. Remove SIGCONT from all queues.
583 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
586 rm_from_queue(sigmask(SIGCONT), &t->pending);
587 } while_each_thread(p, t);
588 } else if (sig == SIGCONT) {
591 * Remove all stop signals from all queues,
592 * and wake all threads.
594 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
598 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
600 * If there is a handler for SIGCONT, we must make
601 * sure that no thread returns to user mode before
602 * we post the signal, in case it was the only
603 * thread eligible to run the signal handler--then
604 * it must not do anything between resuming and
605 * running the handler. With the TIF_SIGPENDING
606 * flag set, the thread will pause and acquire the
607 * siglock that we hold now and until we've queued
608 * the pending signal.
610 * Wake up the stopped thread _after_ setting
613 state = __TASK_STOPPED;
614 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
615 set_tsk_thread_flag(t, TIF_SIGPENDING);
616 state |= TASK_INTERRUPTIBLE;
618 wake_up_state(t, state);
619 } while_each_thread(p, t);
622 * Notify the parent with CLD_CONTINUED if we were stopped.
624 * If we were in the middle of a group stop, we pretend it
625 * was already finished, and then continued. Since SIGCHLD
626 * doesn't queue we report only CLD_STOPPED, as if the next
627 * CLD_CONTINUED was dropped.
630 if (signal->flags & SIGNAL_STOP_STOPPED)
631 why |= SIGNAL_CLD_CONTINUED;
632 else if (signal->group_stop_count)
633 why |= SIGNAL_CLD_STOPPED;
637 * The first thread which returns from finish_stop()
638 * will take ->siglock, notice SIGNAL_CLD_MASK, and
639 * notify its parent. See get_signal_to_deliver().
641 signal->flags = why | SIGNAL_STOP_CONTINUED;
642 signal->group_stop_count = 0;
643 signal->group_exit_code = 0;
646 * We are not stopped, but there could be a stop
647 * signal in the middle of being processed after
648 * being removed from the queue. Clear that too.
650 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
654 return !sig_ignored(p, sig);
658 * Test if P wants to take SIG. After we've checked all threads with this,
659 * it's equivalent to finding no threads not blocking SIG. Any threads not
660 * blocking SIG were ruled out because they are not running and already
661 * have pending signals. Such threads will dequeue from the shared queue
662 * as soon as they're available, so putting the signal on the shared queue
663 * will be equivalent to sending it to one such thread.
665 static inline int wants_signal(int sig, struct task_struct *p)
667 if (sigismember(&p->blocked, sig))
669 if (p->flags & PF_EXITING)
673 if (task_is_stopped_or_traced(p))
675 return task_curr(p) || !signal_pending(p);
678 static void complete_signal(int sig, struct task_struct *p, int group)
680 struct signal_struct *signal = p->signal;
681 struct task_struct *t;
684 * Now find a thread we can wake up to take the signal off the queue.
686 * If the main thread wants the signal, it gets first crack.
687 * Probably the least surprising to the average bear.
689 if (wants_signal(sig, p))
691 else if (!group || thread_group_empty(p))
693 * There is just one thread and it does not need to be woken.
694 * It will dequeue unblocked signals before it runs again.
699 * Otherwise try to find a suitable thread.
701 t = signal->curr_target;
702 while (!wants_signal(sig, t)) {
704 if (t == signal->curr_target)
706 * No thread needs to be woken.
707 * Any eligible threads will see
708 * the signal in the queue soon.
712 signal->curr_target = t;
716 * Found a killable thread. If the signal will be fatal,
717 * then start taking the whole group down immediately.
719 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
720 !sigismember(&t->real_blocked, sig) &&
721 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
723 * This signal will be fatal to the whole group.
725 if (!sig_kernel_coredump(sig)) {
727 * Start a group exit and wake everybody up.
728 * This way we don't have other threads
729 * running and doing things after a slower
730 * thread has the fatal signal pending.
732 signal->flags = SIGNAL_GROUP_EXIT;
733 signal->group_exit_code = sig;
734 signal->group_stop_count = 0;
737 sigaddset(&t->pending.signal, SIGKILL);
738 signal_wake_up(t, 1);
739 } while_each_thread(p, t);
745 * The signal is already in the shared-pending queue.
746 * Tell the chosen thread to wake up and dequeue it.
748 signal_wake_up(t, sig == SIGKILL);
752 static inline int legacy_queue(struct sigpending *signals, int sig)
754 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
757 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
760 struct sigpending *pending;
763 assert_spin_locked(&t->sighand->siglock);
764 if (!prepare_signal(sig, t))
767 pending = group ? &t->signal->shared_pending : &t->pending;
769 * Short-circuit ignored signals and support queuing
770 * exactly one non-rt signal, so that we can get more
771 * detailed information about the cause of the signal.
773 if (legacy_queue(pending, sig))
776 * fast-pathed signals for kernel-internal things like SIGSTOP
779 if (info == SEND_SIG_FORCED)
782 /* Real-time signals must be queued if sent by sigqueue, or
783 some other real-time mechanism. It is implementation
784 defined whether kill() does so. We attempt to do so, on
785 the principle of least surprise, but since kill is not
786 allowed to fail with EAGAIN when low on memory we just
787 make sure at least one signal gets delivered and don't
788 pass on the info struct. */
790 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
791 (is_si_special(info) ||
792 info->si_code >= 0)));
794 list_add_tail(&q->list, &pending->list);
795 switch ((unsigned long) info) {
796 case (unsigned long) SEND_SIG_NOINFO:
797 q->info.si_signo = sig;
798 q->info.si_errno = 0;
799 q->info.si_code = SI_USER;
800 q->info.si_pid = task_pid_vnr(current);
801 q->info.si_uid = current->uid;
803 case (unsigned long) SEND_SIG_PRIV:
804 q->info.si_signo = sig;
805 q->info.si_errno = 0;
806 q->info.si_code = SI_KERNEL;
811 copy_siginfo(&q->info, info);
814 } else if (!is_si_special(info)) {
815 if (sig >= SIGRTMIN && info->si_code != SI_USER)
817 * Queue overflow, abort. We may abort if the signal was rt
818 * and sent by user using something other than kill().
824 signalfd_notify(t, sig);
825 sigaddset(&pending->signal, sig);
826 complete_signal(sig, t, group);
830 int print_fatal_signals;
832 static void print_fatal_signal(struct pt_regs *regs, int signr)
834 printk("%s/%d: potentially unexpected fatal signal %d.\n",
835 current->comm, task_pid_nr(current), signr);
837 #if defined(__i386__) && !defined(__arch_um__)
838 printk("code at %08lx: ", regs->ip);
841 for (i = 0; i < 16; i++) {
844 __get_user(insn, (unsigned char *)(regs->ip + i));
845 printk("%02x ", insn);
853 static int __init setup_print_fatal_signals(char *str)
855 get_option (&str, &print_fatal_signals);
860 __setup("print-fatal-signals=", setup_print_fatal_signals);
863 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
865 return send_signal(sig, info, p, 1);
869 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
871 return send_signal(sig, info, t, 0);
875 * Force a signal that the process can't ignore: if necessary
876 * we unblock the signal and change any SIG_IGN to SIG_DFL.
878 * Note: If we unblock the signal, we always reset it to SIG_DFL,
879 * since we do not want to have a signal handler that was blocked
880 * be invoked when user space had explicitly blocked it.
882 * We don't want to have recursive SIGSEGV's etc, for example.
885 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
887 unsigned long int flags;
888 int ret, blocked, ignored;
889 struct k_sigaction *action;
891 spin_lock_irqsave(&t->sighand->siglock, flags);
892 action = &t->sighand->action[sig-1];
893 ignored = action->sa.sa_handler == SIG_IGN;
894 blocked = sigismember(&t->blocked, sig);
895 if (blocked || ignored) {
896 action->sa.sa_handler = SIG_DFL;
898 sigdelset(&t->blocked, sig);
899 recalc_sigpending_and_wake(t);
902 ret = specific_send_sig_info(sig, info, t);
903 spin_unlock_irqrestore(&t->sighand->siglock, flags);
909 force_sig_specific(int sig, struct task_struct *t)
911 force_sig_info(sig, SEND_SIG_FORCED, t);
915 * Nuke all other threads in the group.
917 void zap_other_threads(struct task_struct *p)
919 struct task_struct *t;
921 p->signal->group_stop_count = 0;
923 for (t = next_thread(p); t != p; t = next_thread(t)) {
925 * Don't bother with already dead threads
930 /* SIGKILL will be handled before any pending SIGSTOP */
931 sigaddset(&t->pending.signal, SIGKILL);
932 signal_wake_up(t, 1);
936 int __fatal_signal_pending(struct task_struct *tsk)
938 return sigismember(&tsk->pending.signal, SIGKILL);
940 EXPORT_SYMBOL(__fatal_signal_pending);
942 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
944 struct sighand_struct *sighand;
948 sighand = rcu_dereference(tsk->sighand);
949 if (unlikely(sighand == NULL))
952 spin_lock_irqsave(&sighand->siglock, *flags);
953 if (likely(sighand == tsk->sighand))
955 spin_unlock_irqrestore(&sighand->siglock, *flags);
962 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
967 ret = check_kill_permission(sig, info, p);
971 if (lock_task_sighand(p, &flags)) {
972 ret = __group_send_sig_info(sig, info, p);
973 unlock_task_sighand(p, &flags);
981 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
982 * control characters do (^C, ^Z etc)
985 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
987 struct task_struct *p = NULL;
992 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
993 int err = group_send_sig_info(sig, info, p);
996 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
997 return success ? 0 : retval;
1000 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1003 struct task_struct *p;
1007 p = pid_task(pid, PIDTYPE_PID);
1009 error = group_send_sig_info(sig, info, p);
1010 if (unlikely(error == -ESRCH))
1012 * The task was unhashed in between, try again.
1013 * If it is dead, pid_task() will return NULL,
1014 * if we race with de_thread() it will find the
1025 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1029 error = kill_pid_info(sig, info, find_vpid(pid));
1034 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1035 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1036 uid_t uid, uid_t euid, u32 secid)
1039 struct task_struct *p;
1041 if (!valid_signal(sig))
1044 read_lock(&tasklist_lock);
1045 p = pid_task(pid, PIDTYPE_PID);
1050 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1051 && (euid != p->suid) && (euid != p->uid)
1052 && (uid != p->suid) && (uid != p->uid)) {
1056 ret = security_task_kill(p, info, sig, secid);
1059 if (sig && p->sighand) {
1060 unsigned long flags;
1061 spin_lock_irqsave(&p->sighand->siglock, flags);
1062 ret = __group_send_sig_info(sig, info, p);
1063 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1066 read_unlock(&tasklist_lock);
1069 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1072 * kill_something_info() interprets pid in interesting ways just like kill(2).
1074 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1075 * is probably wrong. Should make it like BSD or SYSV.
1078 static int kill_something_info(int sig, struct siginfo *info, int pid)
1084 ret = kill_pid_info(sig, info, find_vpid(pid));
1089 read_lock(&tasklist_lock);
1091 ret = __kill_pgrp_info(sig, info,
1092 pid ? find_vpid(-pid) : task_pgrp(current));
1094 int retval = 0, count = 0;
1095 struct task_struct * p;
1097 for_each_process(p) {
1098 if (p->pid > 1 && !same_thread_group(p, current)) {
1099 int err = group_send_sig_info(sig, info, p);
1105 ret = count ? retval : -ESRCH;
1107 read_unlock(&tasklist_lock);
1113 * These are for backward compatibility with the rest of the kernel source.
1117 * The caller must ensure the task can't exit.
1120 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1123 unsigned long flags;
1126 * Make sure legacy kernel users don't send in bad values
1127 * (normal paths check this in check_kill_permission).
1129 if (!valid_signal(sig))
1132 spin_lock_irqsave(&p->sighand->siglock, flags);
1133 ret = specific_send_sig_info(sig, info, p);
1134 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1138 #define __si_special(priv) \
1139 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1142 send_sig(int sig, struct task_struct *p, int priv)
1144 return send_sig_info(sig, __si_special(priv), p);
1148 force_sig(int sig, struct task_struct *p)
1150 force_sig_info(sig, SEND_SIG_PRIV, p);
1154 * When things go south during signal handling, we
1155 * will force a SIGSEGV. And if the signal that caused
1156 * the problem was already a SIGSEGV, we'll want to
1157 * make sure we don't even try to deliver the signal..
1160 force_sigsegv(int sig, struct task_struct *p)
1162 if (sig == SIGSEGV) {
1163 unsigned long flags;
1164 spin_lock_irqsave(&p->sighand->siglock, flags);
1165 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1166 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1168 force_sig(SIGSEGV, p);
1172 int kill_pgrp(struct pid *pid, int sig, int priv)
1176 read_lock(&tasklist_lock);
1177 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1178 read_unlock(&tasklist_lock);
1182 EXPORT_SYMBOL(kill_pgrp);
1184 int kill_pid(struct pid *pid, int sig, int priv)
1186 return kill_pid_info(sig, __si_special(priv), pid);
1188 EXPORT_SYMBOL(kill_pid);
1191 kill_proc(pid_t pid, int sig, int priv)
1196 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1202 * These functions support sending signals using preallocated sigqueue
1203 * structures. This is needed "because realtime applications cannot
1204 * afford to lose notifications of asynchronous events, like timer
1205 * expirations or I/O completions". In the case of Posix Timers
1206 * we allocate the sigqueue structure from the timer_create. If this
1207 * allocation fails we are able to report the failure to the application
1208 * with an EAGAIN error.
1211 struct sigqueue *sigqueue_alloc(void)
1215 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1216 q->flags |= SIGQUEUE_PREALLOC;
1220 void sigqueue_free(struct sigqueue *q)
1222 unsigned long flags;
1223 spinlock_t *lock = ¤t->sighand->siglock;
1225 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1227 * If the signal is still pending remove it from the
1228 * pending queue. We must hold ->siglock while testing
1229 * q->list to serialize with collect_signal().
1231 spin_lock_irqsave(lock, flags);
1232 if (!list_empty(&q->list))
1233 list_del_init(&q->list);
1234 spin_unlock_irqrestore(lock, flags);
1236 q->flags &= ~SIGQUEUE_PREALLOC;
1240 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1242 int sig = q->info.si_signo;
1243 struct sigpending *pending;
1244 unsigned long flags;
1247 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1250 if (!likely(lock_task_sighand(t, &flags)))
1253 ret = 1; /* the signal is ignored */
1254 if (!prepare_signal(sig, t))
1258 if (unlikely(!list_empty(&q->list))) {
1260 * If an SI_TIMER entry is already queue just increment
1261 * the overrun count.
1263 BUG_ON(q->info.si_code != SI_TIMER);
1264 q->info.si_overrun++;
1268 signalfd_notify(t, sig);
1269 pending = group ? &t->signal->shared_pending : &t->pending;
1270 list_add_tail(&q->list, &pending->list);
1271 sigaddset(&pending->signal, sig);
1272 complete_signal(sig, t, group);
1274 unlock_task_sighand(t, &flags);
1280 * Wake up any threads in the parent blocked in wait* syscalls.
1282 static inline void __wake_up_parent(struct task_struct *p,
1283 struct task_struct *parent)
1285 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1289 * Let a parent know about the death of a child.
1290 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1293 void do_notify_parent(struct task_struct *tsk, int sig)
1295 struct siginfo info;
1296 unsigned long flags;
1297 struct sighand_struct *psig;
1301 /* do_notify_parent_cldstop should have been called instead. */
1302 BUG_ON(task_is_stopped_or_traced(tsk));
1304 BUG_ON(!tsk->ptrace &&
1305 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1307 info.si_signo = sig;
1310 * we are under tasklist_lock here so our parent is tied to
1311 * us and cannot exit and release its namespace.
1313 * the only it can is to switch its nsproxy with sys_unshare,
1314 * bu uncharing pid namespaces is not allowed, so we'll always
1315 * see relevant namespace
1317 * write_lock() currently calls preempt_disable() which is the
1318 * same as rcu_read_lock(), but according to Oleg, this is not
1319 * correct to rely on this
1322 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1325 info.si_uid = tsk->uid;
1327 /* FIXME: find out whether or not this is supposed to be c*time. */
1328 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1329 tsk->signal->utime));
1330 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1331 tsk->signal->stime));
1333 info.si_status = tsk->exit_code & 0x7f;
1334 if (tsk->exit_code & 0x80)
1335 info.si_code = CLD_DUMPED;
1336 else if (tsk->exit_code & 0x7f)
1337 info.si_code = CLD_KILLED;
1339 info.si_code = CLD_EXITED;
1340 info.si_status = tsk->exit_code >> 8;
1343 psig = tsk->parent->sighand;
1344 spin_lock_irqsave(&psig->siglock, flags);
1345 if (!tsk->ptrace && sig == SIGCHLD &&
1346 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1347 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1349 * We are exiting and our parent doesn't care. POSIX.1
1350 * defines special semantics for setting SIGCHLD to SIG_IGN
1351 * or setting the SA_NOCLDWAIT flag: we should be reaped
1352 * automatically and not left for our parent's wait4 call.
1353 * Rather than having the parent do it as a magic kind of
1354 * signal handler, we just set this to tell do_exit that we
1355 * can be cleaned up without becoming a zombie. Note that
1356 * we still call __wake_up_parent in this case, because a
1357 * blocked sys_wait4 might now return -ECHILD.
1359 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1360 * is implementation-defined: we do (if you don't want
1361 * it, just use SIG_IGN instead).
1363 tsk->exit_signal = -1;
1364 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1367 if (valid_signal(sig) && sig > 0)
1368 __group_send_sig_info(sig, &info, tsk->parent);
1369 __wake_up_parent(tsk, tsk->parent);
1370 spin_unlock_irqrestore(&psig->siglock, flags);
1373 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1375 struct siginfo info;
1376 unsigned long flags;
1377 struct task_struct *parent;
1378 struct sighand_struct *sighand;
1380 if (tsk->ptrace & PT_PTRACED)
1381 parent = tsk->parent;
1383 tsk = tsk->group_leader;
1384 parent = tsk->real_parent;
1387 info.si_signo = SIGCHLD;
1390 * see comment in do_notify_parent() abot the following 3 lines
1393 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1396 info.si_uid = tsk->uid;
1398 /* FIXME: find out whether or not this is supposed to be c*time. */
1399 info.si_utime = cputime_to_jiffies(tsk->utime);
1400 info.si_stime = cputime_to_jiffies(tsk->stime);
1405 info.si_status = SIGCONT;
1408 info.si_status = tsk->signal->group_exit_code & 0x7f;
1411 info.si_status = tsk->exit_code & 0x7f;
1417 sighand = parent->sighand;
1418 spin_lock_irqsave(&sighand->siglock, flags);
1419 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1420 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1421 __group_send_sig_info(SIGCHLD, &info, parent);
1423 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1425 __wake_up_parent(tsk, parent);
1426 spin_unlock_irqrestore(&sighand->siglock, flags);
1429 static inline int may_ptrace_stop(void)
1431 if (!likely(current->ptrace & PT_PTRACED))
1434 * Are we in the middle of do_coredump?
1435 * If so and our tracer is also part of the coredump stopping
1436 * is a deadlock situation, and pointless because our tracer
1437 * is dead so don't allow us to stop.
1438 * If SIGKILL was already sent before the caller unlocked
1439 * ->siglock we must see ->core_waiters != 0. Otherwise it
1440 * is safe to enter schedule().
1442 if (unlikely(current->mm->core_waiters) &&
1443 unlikely(current->mm == current->parent->mm))
1450 * Return nonzero if there is a SIGKILL that should be waking us up.
1451 * Called with the siglock held.
1453 static int sigkill_pending(struct task_struct *tsk)
1455 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1456 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1457 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1461 * This must be called with current->sighand->siglock held.
1463 * This should be the path for all ptrace stops.
1464 * We always set current->last_siginfo while stopped here.
1465 * That makes it a way to test a stopped process for
1466 * being ptrace-stopped vs being job-control-stopped.
1468 * If we actually decide not to stop at all because the tracer
1469 * is gone, we keep current->exit_code unless clear_code.
1471 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1475 if (arch_ptrace_stop_needed(exit_code, info)) {
1477 * The arch code has something special to do before a
1478 * ptrace stop. This is allowed to block, e.g. for faults
1479 * on user stack pages. We can't keep the siglock while
1480 * calling arch_ptrace_stop, so we must release it now.
1481 * To preserve proper semantics, we must do this before
1482 * any signal bookkeeping like checking group_stop_count.
1483 * Meanwhile, a SIGKILL could come in before we retake the
1484 * siglock. That must prevent us from sleeping in TASK_TRACED.
1485 * So after regaining the lock, we must check for SIGKILL.
1487 spin_unlock_irq(¤t->sighand->siglock);
1488 arch_ptrace_stop(exit_code, info);
1489 spin_lock_irq(¤t->sighand->siglock);
1490 killed = sigkill_pending(current);
1494 * If there is a group stop in progress,
1495 * we must participate in the bookkeeping.
1497 if (current->signal->group_stop_count > 0)
1498 --current->signal->group_stop_count;
1500 current->last_siginfo = info;
1501 current->exit_code = exit_code;
1503 /* Let the debugger run. */
1504 __set_current_state(TASK_TRACED);
1505 spin_unlock_irq(¤t->sighand->siglock);
1506 read_lock(&tasklist_lock);
1507 if (!unlikely(killed) && may_ptrace_stop()) {
1508 do_notify_parent_cldstop(current, CLD_TRAPPED);
1509 read_unlock(&tasklist_lock);
1513 * By the time we got the lock, our tracer went away.
1514 * Don't drop the lock yet, another tracer may come.
1516 __set_current_state(TASK_RUNNING);
1518 current->exit_code = 0;
1519 read_unlock(&tasklist_lock);
1523 * While in TASK_TRACED, we were considered "frozen enough".
1524 * Now that we woke up, it's crucial if we're supposed to be
1525 * frozen that we freeze now before running anything substantial.
1530 * We are back. Now reacquire the siglock before touching
1531 * last_siginfo, so that we are sure to have synchronized with
1532 * any signal-sending on another CPU that wants to examine it.
1534 spin_lock_irq(¤t->sighand->siglock);
1535 current->last_siginfo = NULL;
1538 * Queued signals ignored us while we were stopped for tracing.
1539 * So check for any that we should take before resuming user mode.
1540 * This sets TIF_SIGPENDING, but never clears it.
1542 recalc_sigpending_tsk(current);
1545 void ptrace_notify(int exit_code)
1549 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1551 memset(&info, 0, sizeof info);
1552 info.si_signo = SIGTRAP;
1553 info.si_code = exit_code;
1554 info.si_pid = task_pid_vnr(current);
1555 info.si_uid = current->uid;
1557 /* Let the debugger run. */
1558 spin_lock_irq(¤t->sighand->siglock);
1559 ptrace_stop(exit_code, 1, &info);
1560 spin_unlock_irq(¤t->sighand->siglock);
1564 finish_stop(int stop_count)
1567 * If there are no other threads in the group, or if there is
1568 * a group stop in progress and we are the last to stop,
1569 * report to the parent. When ptraced, every thread reports itself.
1571 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1572 read_lock(&tasklist_lock);
1573 do_notify_parent_cldstop(current, CLD_STOPPED);
1574 read_unlock(&tasklist_lock);
1579 } while (try_to_freeze());
1581 * Now we don't run again until continued.
1583 current->exit_code = 0;
1587 * This performs the stopping for SIGSTOP and other stop signals.
1588 * We have to stop all threads in the thread group.
1589 * Returns nonzero if we've actually stopped and released the siglock.
1590 * Returns zero if we didn't stop and still hold the siglock.
1592 static int do_signal_stop(int signr)
1594 struct signal_struct *sig = current->signal;
1597 if (sig->group_stop_count > 0) {
1599 * There is a group stop in progress. We don't need to
1600 * start another one.
1602 stop_count = --sig->group_stop_count;
1604 struct task_struct *t;
1606 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1607 unlikely(signal_group_exit(sig)))
1610 * There is no group stop already in progress.
1611 * We must initiate one now.
1613 sig->group_exit_code = signr;
1616 for (t = next_thread(current); t != current; t = next_thread(t))
1618 * Setting state to TASK_STOPPED for a group
1619 * stop is always done with the siglock held,
1620 * so this check has no races.
1622 if (!(t->flags & PF_EXITING) &&
1623 !task_is_stopped_or_traced(t)) {
1625 signal_wake_up(t, 0);
1627 sig->group_stop_count = stop_count;
1630 if (stop_count == 0)
1631 sig->flags = SIGNAL_STOP_STOPPED;
1632 current->exit_code = sig->group_exit_code;
1633 __set_current_state(TASK_STOPPED);
1635 spin_unlock_irq(¤t->sighand->siglock);
1636 finish_stop(stop_count);
1640 static int ptrace_signal(int signr, siginfo_t *info,
1641 struct pt_regs *regs, void *cookie)
1643 if (!(current->ptrace & PT_PTRACED))
1646 ptrace_signal_deliver(regs, cookie);
1648 /* Let the debugger run. */
1649 ptrace_stop(signr, 0, info);
1651 /* We're back. Did the debugger cancel the sig? */
1652 signr = current->exit_code;
1656 current->exit_code = 0;
1658 /* Update the siginfo structure if the signal has
1659 changed. If the debugger wanted something
1660 specific in the siginfo structure then it should
1661 have updated *info via PTRACE_SETSIGINFO. */
1662 if (signr != info->si_signo) {
1663 info->si_signo = signr;
1665 info->si_code = SI_USER;
1666 info->si_pid = task_pid_vnr(current->parent);
1667 info->si_uid = current->parent->uid;
1670 /* If the (new) signal is now blocked, requeue it. */
1671 if (sigismember(¤t->blocked, signr)) {
1672 specific_send_sig_info(signr, info, current);
1679 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1680 struct pt_regs *regs, void *cookie)
1682 struct sighand_struct *sighand = current->sighand;
1683 struct signal_struct *signal = current->signal;
1688 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1689 * While in TASK_STOPPED, we were considered "frozen enough".
1690 * Now that we woke up, it's crucial if we're supposed to be
1691 * frozen that we freeze now before running anything substantial.
1695 spin_lock_irq(&sighand->siglock);
1697 * Every stopped thread goes here after wakeup. Check to see if
1698 * we should notify the parent, prepare_signal(SIGCONT) encodes
1699 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1701 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1702 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1703 ? CLD_CONTINUED : CLD_STOPPED;
1704 signal->flags &= ~SIGNAL_CLD_MASK;
1705 spin_unlock_irq(&sighand->siglock);
1707 read_lock(&tasklist_lock);
1708 do_notify_parent_cldstop(current->group_leader, why);
1709 read_unlock(&tasklist_lock);
1714 struct k_sigaction *ka;
1716 if (unlikely(signal->group_stop_count > 0) &&
1720 signr = dequeue_signal(current, ¤t->blocked, info);
1722 break; /* will return 0 */
1724 if (signr != SIGKILL) {
1725 signr = ptrace_signal(signr, info, regs, cookie);
1730 ka = &sighand->action[signr-1];
1731 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1733 if (ka->sa.sa_handler != SIG_DFL) {
1734 /* Run the handler. */
1737 if (ka->sa.sa_flags & SA_ONESHOT)
1738 ka->sa.sa_handler = SIG_DFL;
1740 break; /* will return non-zero "signr" value */
1744 * Now we are doing the default action for this signal.
1746 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1750 * Global init gets no signals it doesn't want.
1752 if (is_global_init(current))
1755 if (sig_kernel_stop(signr)) {
1757 * The default action is to stop all threads in
1758 * the thread group. The job control signals
1759 * do nothing in an orphaned pgrp, but SIGSTOP
1760 * always works. Note that siglock needs to be
1761 * dropped during the call to is_orphaned_pgrp()
1762 * because of lock ordering with tasklist_lock.
1763 * This allows an intervening SIGCONT to be posted.
1764 * We need to check for that and bail out if necessary.
1766 if (signr != SIGSTOP) {
1767 spin_unlock_irq(&sighand->siglock);
1769 /* signals can be posted during this window */
1771 if (is_current_pgrp_orphaned())
1774 spin_lock_irq(&sighand->siglock);
1777 if (likely(do_signal_stop(signr))) {
1778 /* It released the siglock. */
1783 * We didn't actually stop, due to a race
1784 * with SIGCONT or something like that.
1789 spin_unlock_irq(&sighand->siglock);
1792 * Anything else is fatal, maybe with a core dump.
1794 current->flags |= PF_SIGNALED;
1796 if (sig_kernel_coredump(signr)) {
1797 if (print_fatal_signals)
1798 print_fatal_signal(regs, signr);
1800 * If it was able to dump core, this kills all
1801 * other threads in the group and synchronizes with
1802 * their demise. If we lost the race with another
1803 * thread getting here, it set group_exit_code
1804 * first and our do_group_exit call below will use
1805 * that value and ignore the one we pass it.
1807 do_coredump((long)signr, signr, regs);
1811 * Death signals, no core dump.
1813 do_group_exit(signr);
1816 spin_unlock_irq(&sighand->siglock);
1820 void exit_signals(struct task_struct *tsk)
1823 struct task_struct *t;
1825 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1826 tsk->flags |= PF_EXITING;
1830 spin_lock_irq(&tsk->sighand->siglock);
1832 * From now this task is not visible for group-wide signals,
1833 * see wants_signal(), do_signal_stop().
1835 tsk->flags |= PF_EXITING;
1836 if (!signal_pending(tsk))
1839 /* It could be that __group_complete_signal() choose us to
1840 * notify about group-wide signal. Another thread should be
1841 * woken now to take the signal since we will not.
1843 for (t = tsk; (t = next_thread(t)) != tsk; )
1844 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1845 recalc_sigpending_and_wake(t);
1847 if (unlikely(tsk->signal->group_stop_count) &&
1848 !--tsk->signal->group_stop_count) {
1849 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1853 spin_unlock_irq(&tsk->sighand->siglock);
1855 if (unlikely(group_stop)) {
1856 read_lock(&tasklist_lock);
1857 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1858 read_unlock(&tasklist_lock);
1862 EXPORT_SYMBOL(recalc_sigpending);
1863 EXPORT_SYMBOL_GPL(dequeue_signal);
1864 EXPORT_SYMBOL(flush_signals);
1865 EXPORT_SYMBOL(force_sig);
1866 EXPORT_SYMBOL(kill_proc);
1867 EXPORT_SYMBOL(ptrace_notify);
1868 EXPORT_SYMBOL(send_sig);
1869 EXPORT_SYMBOL(send_sig_info);
1870 EXPORT_SYMBOL(sigprocmask);
1871 EXPORT_SYMBOL(block_all_signals);
1872 EXPORT_SYMBOL(unblock_all_signals);
1876 * System call entry points.
1879 asmlinkage long sys_restart_syscall(void)
1881 struct restart_block *restart = ¤t_thread_info()->restart_block;
1882 return restart->fn(restart);
1885 long do_no_restart_syscall(struct restart_block *param)
1891 * We don't need to get the kernel lock - this is all local to this
1892 * particular thread.. (and that's good, because this is _heavily_
1893 * used by various programs)
1897 * This is also useful for kernel threads that want to temporarily
1898 * (or permanently) block certain signals.
1900 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1901 * interface happily blocks "unblockable" signals like SIGKILL
1904 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1908 spin_lock_irq(¤t->sighand->siglock);
1910 *oldset = current->blocked;
1915 sigorsets(¤t->blocked, ¤t->blocked, set);
1918 signandsets(¤t->blocked, ¤t->blocked, set);
1921 current->blocked = *set;
1926 recalc_sigpending();
1927 spin_unlock_irq(¤t->sighand->siglock);
1933 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1935 int error = -EINVAL;
1936 sigset_t old_set, new_set;
1938 /* XXX: Don't preclude handling different sized sigset_t's. */
1939 if (sigsetsize != sizeof(sigset_t))
1944 if (copy_from_user(&new_set, set, sizeof(*set)))
1946 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1948 error = sigprocmask(how, &new_set, &old_set);
1954 spin_lock_irq(¤t->sighand->siglock);
1955 old_set = current->blocked;
1956 spin_unlock_irq(¤t->sighand->siglock);
1960 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1968 long do_sigpending(void __user *set, unsigned long sigsetsize)
1970 long error = -EINVAL;
1973 if (sigsetsize > sizeof(sigset_t))
1976 spin_lock_irq(¤t->sighand->siglock);
1977 sigorsets(&pending, ¤t->pending.signal,
1978 ¤t->signal->shared_pending.signal);
1979 spin_unlock_irq(¤t->sighand->siglock);
1981 /* Outside the lock because only this thread touches it. */
1982 sigandsets(&pending, ¤t->blocked, &pending);
1985 if (!copy_to_user(set, &pending, sigsetsize))
1993 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
1995 return do_sigpending(set, sigsetsize);
1998 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2000 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2004 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2006 if (from->si_code < 0)
2007 return __copy_to_user(to, from, sizeof(siginfo_t))
2010 * If you change siginfo_t structure, please be sure
2011 * this code is fixed accordingly.
2012 * Please remember to update the signalfd_copyinfo() function
2013 * inside fs/signalfd.c too, in case siginfo_t changes.
2014 * It should never copy any pad contained in the structure
2015 * to avoid security leaks, but must copy the generic
2016 * 3 ints plus the relevant union member.
2018 err = __put_user(from->si_signo, &to->si_signo);
2019 err |= __put_user(from->si_errno, &to->si_errno);
2020 err |= __put_user((short)from->si_code, &to->si_code);
2021 switch (from->si_code & __SI_MASK) {
2023 err |= __put_user(from->si_pid, &to->si_pid);
2024 err |= __put_user(from->si_uid, &to->si_uid);
2027 err |= __put_user(from->si_tid, &to->si_tid);
2028 err |= __put_user(from->si_overrun, &to->si_overrun);
2029 err |= __put_user(from->si_ptr, &to->si_ptr);
2032 err |= __put_user(from->si_band, &to->si_band);
2033 err |= __put_user(from->si_fd, &to->si_fd);
2036 err |= __put_user(from->si_addr, &to->si_addr);
2037 #ifdef __ARCH_SI_TRAPNO
2038 err |= __put_user(from->si_trapno, &to->si_trapno);
2042 err |= __put_user(from->si_pid, &to->si_pid);
2043 err |= __put_user(from->si_uid, &to->si_uid);
2044 err |= __put_user(from->si_status, &to->si_status);
2045 err |= __put_user(from->si_utime, &to->si_utime);
2046 err |= __put_user(from->si_stime, &to->si_stime);
2048 case __SI_RT: /* This is not generated by the kernel as of now. */
2049 case __SI_MESGQ: /* But this is */
2050 err |= __put_user(from->si_pid, &to->si_pid);
2051 err |= __put_user(from->si_uid, &to->si_uid);
2052 err |= __put_user(from->si_ptr, &to->si_ptr);
2054 default: /* this is just in case for now ... */
2055 err |= __put_user(from->si_pid, &to->si_pid);
2056 err |= __put_user(from->si_uid, &to->si_uid);
2065 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2066 siginfo_t __user *uinfo,
2067 const struct timespec __user *uts,
2076 /* XXX: Don't preclude handling different sized sigset_t's. */
2077 if (sigsetsize != sizeof(sigset_t))
2080 if (copy_from_user(&these, uthese, sizeof(these)))
2084 * Invert the set of allowed signals to get those we
2087 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2091 if (copy_from_user(&ts, uts, sizeof(ts)))
2093 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2098 spin_lock_irq(¤t->sighand->siglock);
2099 sig = dequeue_signal(current, &these, &info);
2101 timeout = MAX_SCHEDULE_TIMEOUT;
2103 timeout = (timespec_to_jiffies(&ts)
2104 + (ts.tv_sec || ts.tv_nsec));
2107 /* None ready -- temporarily unblock those we're
2108 * interested while we are sleeping in so that we'll
2109 * be awakened when they arrive. */
2110 current->real_blocked = current->blocked;
2111 sigandsets(¤t->blocked, ¤t->blocked, &these);
2112 recalc_sigpending();
2113 spin_unlock_irq(¤t->sighand->siglock);
2115 timeout = schedule_timeout_interruptible(timeout);
2117 spin_lock_irq(¤t->sighand->siglock);
2118 sig = dequeue_signal(current, &these, &info);
2119 current->blocked = current->real_blocked;
2120 siginitset(¤t->real_blocked, 0);
2121 recalc_sigpending();
2124 spin_unlock_irq(¤t->sighand->siglock);
2129 if (copy_siginfo_to_user(uinfo, &info))
2142 sys_kill(int pid, int sig)
2144 struct siginfo info;
2146 info.si_signo = sig;
2148 info.si_code = SI_USER;
2149 info.si_pid = task_tgid_vnr(current);
2150 info.si_uid = current->uid;
2152 return kill_something_info(sig, &info, pid);
2155 static int do_tkill(int tgid, int pid, int sig)
2158 struct siginfo info;
2159 struct task_struct *p;
2160 unsigned long flags;
2163 info.si_signo = sig;
2165 info.si_code = SI_TKILL;
2166 info.si_pid = task_tgid_vnr(current);
2167 info.si_uid = current->uid;
2170 p = find_task_by_vpid(pid);
2171 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2172 error = check_kill_permission(sig, &info, p);
2174 * The null signal is a permissions and process existence
2175 * probe. No signal is actually delivered.
2177 * If lock_task_sighand() fails we pretend the task dies
2178 * after receiving the signal. The window is tiny, and the
2179 * signal is private anyway.
2181 if (!error && sig && lock_task_sighand(p, &flags)) {
2182 error = specific_send_sig_info(sig, &info, p);
2183 unlock_task_sighand(p, &flags);
2192 * sys_tgkill - send signal to one specific thread
2193 * @tgid: the thread group ID of the thread
2194 * @pid: the PID of the thread
2195 * @sig: signal to be sent
2197 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2198 * exists but it's not belonging to the target process anymore. This
2199 * method solves the problem of threads exiting and PIDs getting reused.
2201 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2203 /* This is only valid for single tasks */
2204 if (pid <= 0 || tgid <= 0)
2207 return do_tkill(tgid, pid, sig);
2211 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2214 sys_tkill(int pid, int sig)
2216 /* This is only valid for single tasks */
2220 return do_tkill(0, pid, sig);
2224 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2228 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2231 /* Not even root can pretend to send signals from the kernel.
2232 Nor can they impersonate a kill(), which adds source info. */
2233 if (info.si_code >= 0)
2235 info.si_signo = sig;
2237 /* POSIX.1b doesn't mention process groups. */
2238 return kill_proc_info(sig, &info, pid);
2241 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2243 struct task_struct *t = current;
2244 struct k_sigaction *k;
2247 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2250 k = &t->sighand->action[sig-1];
2252 spin_lock_irq(¤t->sighand->siglock);
2257 sigdelsetmask(&act->sa.sa_mask,
2258 sigmask(SIGKILL) | sigmask(SIGSTOP));
2262 * "Setting a signal action to SIG_IGN for a signal that is
2263 * pending shall cause the pending signal to be discarded,
2264 * whether or not it is blocked."
2266 * "Setting a signal action to SIG_DFL for a signal that is
2267 * pending and whose default action is to ignore the signal
2268 * (for example, SIGCHLD), shall cause the pending signal to
2269 * be discarded, whether or not it is blocked"
2271 if (__sig_ignored(t, sig)) {
2273 sigaddset(&mask, sig);
2274 rm_from_queue_full(&mask, &t->signal->shared_pending);
2276 rm_from_queue_full(&mask, &t->pending);
2278 } while (t != current);
2282 spin_unlock_irq(¤t->sighand->siglock);
2287 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2293 oss.ss_sp = (void __user *) current->sas_ss_sp;
2294 oss.ss_size = current->sas_ss_size;
2295 oss.ss_flags = sas_ss_flags(sp);
2304 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2305 || __get_user(ss_sp, &uss->ss_sp)
2306 || __get_user(ss_flags, &uss->ss_flags)
2307 || __get_user(ss_size, &uss->ss_size))
2311 if (on_sig_stack(sp))
2317 * Note - this code used to test ss_flags incorrectly
2318 * old code may have been written using ss_flags==0
2319 * to mean ss_flags==SS_ONSTACK (as this was the only
2320 * way that worked) - this fix preserves that older
2323 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2326 if (ss_flags == SS_DISABLE) {
2331 if (ss_size < MINSIGSTKSZ)
2335 current->sas_ss_sp = (unsigned long) ss_sp;
2336 current->sas_ss_size = ss_size;
2341 if (copy_to_user(uoss, &oss, sizeof(oss)))
2350 #ifdef __ARCH_WANT_SYS_SIGPENDING
2353 sys_sigpending(old_sigset_t __user *set)
2355 return do_sigpending(set, sizeof(*set));
2360 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2361 /* Some platforms have their own version with special arguments others
2362 support only sys_rt_sigprocmask. */
2365 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2368 old_sigset_t old_set, new_set;
2372 if (copy_from_user(&new_set, set, sizeof(*set)))
2374 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2376 spin_lock_irq(¤t->sighand->siglock);
2377 old_set = current->blocked.sig[0];
2385 sigaddsetmask(¤t->blocked, new_set);
2388 sigdelsetmask(¤t->blocked, new_set);
2391 current->blocked.sig[0] = new_set;
2395 recalc_sigpending();
2396 spin_unlock_irq(¤t->sighand->siglock);
2402 old_set = current->blocked.sig[0];
2405 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2412 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2414 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2416 sys_rt_sigaction(int sig,
2417 const struct sigaction __user *act,
2418 struct sigaction __user *oact,
2421 struct k_sigaction new_sa, old_sa;
2424 /* XXX: Don't preclude handling different sized sigset_t's. */
2425 if (sigsetsize != sizeof(sigset_t))
2429 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2433 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2436 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2442 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2444 #ifdef __ARCH_WANT_SYS_SGETMASK
2447 * For backwards compatibility. Functionality superseded by sigprocmask.
2453 return current->blocked.sig[0];
2457 sys_ssetmask(int newmask)
2461 spin_lock_irq(¤t->sighand->siglock);
2462 old = current->blocked.sig[0];
2464 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2466 recalc_sigpending();
2467 spin_unlock_irq(¤t->sighand->siglock);
2471 #endif /* __ARCH_WANT_SGETMASK */
2473 #ifdef __ARCH_WANT_SYS_SIGNAL
2475 * For backwards compatibility. Functionality superseded by sigaction.
2477 asmlinkage unsigned long
2478 sys_signal(int sig, __sighandler_t handler)
2480 struct k_sigaction new_sa, old_sa;
2483 new_sa.sa.sa_handler = handler;
2484 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2485 sigemptyset(&new_sa.sa.sa_mask);
2487 ret = do_sigaction(sig, &new_sa, &old_sa);
2489 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2491 #endif /* __ARCH_WANT_SYS_SIGNAL */
2493 #ifdef __ARCH_WANT_SYS_PAUSE
2498 current->state = TASK_INTERRUPTIBLE;
2500 return -ERESTARTNOHAND;
2505 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2506 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2510 /* XXX: Don't preclude handling different sized sigset_t's. */
2511 if (sigsetsize != sizeof(sigset_t))
2514 if (copy_from_user(&newset, unewset, sizeof(newset)))
2516 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2518 spin_lock_irq(¤t->sighand->siglock);
2519 current->saved_sigmask = current->blocked;
2520 current->blocked = newset;
2521 recalc_sigpending();
2522 spin_unlock_irq(¤t->sighand->siglock);
2524 current->state = TASK_INTERRUPTIBLE;
2526 set_thread_flag(TIF_RESTORE_SIGMASK);
2527 return -ERESTARTNOHAND;
2529 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2531 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2536 void __init signals_init(void)
2538 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);