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 void 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;
377 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
380 int sig = next_signal(pending, mask);
383 if (current->notifier) {
384 if (sigismember(current->notifier_mask, sig)) {
385 if (!(current->notifier)(current->notifier_data)) {
386 clear_thread_flag(TIF_SIGPENDING);
392 collect_signal(sig, pending, info);
399 * Dequeue a signal and return the element to the caller, which is
400 * expected to free it.
402 * All callers have to hold the siglock.
404 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
408 /* We only dequeue private signals from ourselves, we don't let
409 * signalfd steal them
411 signr = __dequeue_signal(&tsk->pending, mask, info);
413 signr = __dequeue_signal(&tsk->signal->shared_pending,
418 * itimers are process shared and we restart periodic
419 * itimers in the signal delivery path to prevent DoS
420 * attacks in the high resolution timer case. This is
421 * compliant with the old way of self restarting
422 * itimers, as the SIGALRM is a legacy signal and only
423 * queued once. Changing the restart behaviour to
424 * restart the timer in the signal dequeue path is
425 * reducing the timer noise on heavy loaded !highres
428 if (unlikely(signr == SIGALRM)) {
429 struct hrtimer *tmr = &tsk->signal->real_timer;
431 if (!hrtimer_is_queued(tmr) &&
432 tsk->signal->it_real_incr.tv64 != 0) {
433 hrtimer_forward(tmr, tmr->base->get_time(),
434 tsk->signal->it_real_incr);
435 hrtimer_restart(tmr);
444 if (unlikely(sig_kernel_stop(signr))) {
446 * Set a marker that we have dequeued a stop signal. Our
447 * caller might release the siglock and then the pending
448 * stop signal it is about to process is no longer in the
449 * pending bitmasks, but must still be cleared by a SIGCONT
450 * (and overruled by a SIGKILL). So those cases clear this
451 * shared flag after we've set it. Note that this flag may
452 * remain set after the signal we return is ignored or
453 * handled. That doesn't matter because its only purpose
454 * is to alert stop-signal processing code when another
455 * processor has come along and cleared the flag.
457 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
459 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
461 * Release the siglock to ensure proper locking order
462 * of timer locks outside of siglocks. Note, we leave
463 * irqs disabled here, since the posix-timers code is
464 * about to disable them again anyway.
466 spin_unlock(&tsk->sighand->siglock);
467 do_schedule_next_timer(info);
468 spin_lock(&tsk->sighand->siglock);
474 * Tell a process that it has a new active signal..
476 * NOTE! we rely on the previous spin_lock to
477 * lock interrupts for us! We can only be called with
478 * "siglock" held, and the local interrupt must
479 * have been disabled when that got acquired!
481 * No need to set need_resched since signal event passing
482 * goes through ->blocked
484 void signal_wake_up(struct task_struct *t, int resume)
488 set_tsk_thread_flag(t, TIF_SIGPENDING);
491 * For SIGKILL, we want to wake it up in the stopped/traced/killable
492 * case. We don't check t->state here because there is a race with it
493 * executing another processor and just now entering stopped state.
494 * By using wake_up_state, we ensure the process will wake up and
495 * handle its death signal.
497 mask = TASK_INTERRUPTIBLE;
499 mask |= TASK_WAKEKILL;
500 if (!wake_up_state(t, mask))
505 * Remove signals in mask from the pending set and queue.
506 * Returns 1 if any signals were found.
508 * All callers must be holding the siglock.
510 * This version takes a sigset mask and looks at all signals,
511 * not just those in the first mask word.
513 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
515 struct sigqueue *q, *n;
518 sigandsets(&m, mask, &s->signal);
519 if (sigisemptyset(&m))
522 signandsets(&s->signal, &s->signal, mask);
523 list_for_each_entry_safe(q, n, &s->list, list) {
524 if (sigismember(mask, q->info.si_signo)) {
525 list_del_init(&q->list);
532 * Remove signals in mask from the pending set and queue.
533 * Returns 1 if any signals were found.
535 * All callers must be holding the siglock.
537 static int rm_from_queue(unsigned long mask, struct sigpending *s)
539 struct sigqueue *q, *n;
541 if (!sigtestsetmask(&s->signal, mask))
544 sigdelsetmask(&s->signal, mask);
545 list_for_each_entry_safe(q, n, &s->list, list) {
546 if (q->info.si_signo < SIGRTMIN &&
547 (mask & sigmask(q->info.si_signo))) {
548 list_del_init(&q->list);
556 * Bad permissions for sending the signal
558 static int check_kill_permission(int sig, struct siginfo *info,
559 struct task_struct *t)
564 if (!valid_signal(sig))
567 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
570 error = audit_signal_info(sig, t); /* Let audit system see the signal */
574 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
575 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
576 !capable(CAP_KILL)) {
579 sid = task_session(t);
581 * We don't return the error if sid == NULL. The
582 * task was unhashed, the caller must notice this.
584 if (!sid || sid == task_session(current))
591 return security_task_kill(t, info, sig, 0);
595 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
598 * Handle magic process-wide effects of stop/continue signals. Unlike
599 * the signal actions, these happen immediately at signal-generation
600 * time regardless of blocking, ignoring, or handling. This does the
601 * actual continuing for SIGCONT, but not the actual stopping for stop
602 * signals. The process stop is done as a signal action for SIG_DFL.
604 * Returns true if the signal should be actually delivered, otherwise
605 * it should be dropped.
607 static int prepare_signal(int sig, struct task_struct *p)
609 struct signal_struct *signal = p->signal;
610 struct task_struct *t;
612 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
614 * The process is in the middle of dying, nothing to do.
616 } else if (sig_kernel_stop(sig)) {
618 * This is a stop signal. Remove SIGCONT from all queues.
620 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
623 rm_from_queue(sigmask(SIGCONT), &t->pending);
624 } while_each_thread(p, t);
625 } else if (sig == SIGCONT) {
628 * Remove all stop signals from all queues,
629 * and wake all threads.
631 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
635 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
637 * If there is a handler for SIGCONT, we must make
638 * sure that no thread returns to user mode before
639 * we post the signal, in case it was the only
640 * thread eligible to run the signal handler--then
641 * it must not do anything between resuming and
642 * running the handler. With the TIF_SIGPENDING
643 * flag set, the thread will pause and acquire the
644 * siglock that we hold now and until we've queued
645 * the pending signal.
647 * Wake up the stopped thread _after_ setting
650 state = __TASK_STOPPED;
651 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
652 set_tsk_thread_flag(t, TIF_SIGPENDING);
653 state |= TASK_INTERRUPTIBLE;
655 wake_up_state(t, state);
656 } while_each_thread(p, t);
659 * Notify the parent with CLD_CONTINUED if we were stopped.
661 * If we were in the middle of a group stop, we pretend it
662 * was already finished, and then continued. Since SIGCHLD
663 * doesn't queue we report only CLD_STOPPED, as if the next
664 * CLD_CONTINUED was dropped.
667 if (signal->flags & SIGNAL_STOP_STOPPED)
668 why |= SIGNAL_CLD_CONTINUED;
669 else if (signal->group_stop_count)
670 why |= SIGNAL_CLD_STOPPED;
674 * The first thread which returns from finish_stop()
675 * will take ->siglock, notice SIGNAL_CLD_MASK, and
676 * notify its parent. See get_signal_to_deliver().
678 signal->flags = why | SIGNAL_STOP_CONTINUED;
679 signal->group_stop_count = 0;
680 signal->group_exit_code = 0;
683 * We are not stopped, but there could be a stop
684 * signal in the middle of being processed after
685 * being removed from the queue. Clear that too.
687 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
691 return !sig_ignored(p, sig);
695 * Test if P wants to take SIG. After we've checked all threads with this,
696 * it's equivalent to finding no threads not blocking SIG. Any threads not
697 * blocking SIG were ruled out because they are not running and already
698 * have pending signals. Such threads will dequeue from the shared queue
699 * as soon as they're available, so putting the signal on the shared queue
700 * will be equivalent to sending it to one such thread.
702 static inline int wants_signal(int sig, struct task_struct *p)
704 if (sigismember(&p->blocked, sig))
706 if (p->flags & PF_EXITING)
710 if (task_is_stopped_or_traced(p))
712 return task_curr(p) || !signal_pending(p);
715 static void complete_signal(int sig, struct task_struct *p, int group)
717 struct signal_struct *signal = p->signal;
718 struct task_struct *t;
721 * Now find a thread we can wake up to take the signal off the queue.
723 * If the main thread wants the signal, it gets first crack.
724 * Probably the least surprising to the average bear.
726 if (wants_signal(sig, p))
728 else if (!group || thread_group_empty(p))
730 * There is just one thread and it does not need to be woken.
731 * It will dequeue unblocked signals before it runs again.
736 * Otherwise try to find a suitable thread.
738 t = signal->curr_target;
739 while (!wants_signal(sig, t)) {
741 if (t == signal->curr_target)
743 * No thread needs to be woken.
744 * Any eligible threads will see
745 * the signal in the queue soon.
749 signal->curr_target = t;
753 * Found a killable thread. If the signal will be fatal,
754 * then start taking the whole group down immediately.
756 if (sig_fatal(p, sig) &&
757 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
758 !sigismember(&t->real_blocked, sig) &&
759 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
761 * This signal will be fatal to the whole group.
763 if (!sig_kernel_coredump(sig)) {
765 * Start a group exit and wake everybody up.
766 * This way we don't have other threads
767 * running and doing things after a slower
768 * thread has the fatal signal pending.
770 signal->flags = SIGNAL_GROUP_EXIT;
771 signal->group_exit_code = sig;
772 signal->group_stop_count = 0;
775 sigaddset(&t->pending.signal, SIGKILL);
776 signal_wake_up(t, 1);
777 } while_each_thread(p, t);
783 * The signal is already in the shared-pending queue.
784 * Tell the chosen thread to wake up and dequeue it.
786 signal_wake_up(t, sig == SIGKILL);
790 static inline int legacy_queue(struct sigpending *signals, int sig)
792 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
795 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
798 struct sigpending *pending;
801 assert_spin_locked(&t->sighand->siglock);
802 if (!prepare_signal(sig, t))
805 pending = group ? &t->signal->shared_pending : &t->pending;
807 * Short-circuit ignored signals and support queuing
808 * exactly one non-rt signal, so that we can get more
809 * detailed information about the cause of the signal.
811 if (legacy_queue(pending, sig))
814 * fast-pathed signals for kernel-internal things like SIGSTOP
817 if (info == SEND_SIG_FORCED)
820 /* Real-time signals must be queued if sent by sigqueue, or
821 some other real-time mechanism. It is implementation
822 defined whether kill() does so. We attempt to do so, on
823 the principle of least surprise, but since kill is not
824 allowed to fail with EAGAIN when low on memory we just
825 make sure at least one signal gets delivered and don't
826 pass on the info struct. */
828 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
829 (is_si_special(info) ||
830 info->si_code >= 0)));
832 list_add_tail(&q->list, &pending->list);
833 switch ((unsigned long) info) {
834 case (unsigned long) SEND_SIG_NOINFO:
835 q->info.si_signo = sig;
836 q->info.si_errno = 0;
837 q->info.si_code = SI_USER;
838 q->info.si_pid = task_pid_vnr(current);
839 q->info.si_uid = current->uid;
841 case (unsigned long) SEND_SIG_PRIV:
842 q->info.si_signo = sig;
843 q->info.si_errno = 0;
844 q->info.si_code = SI_KERNEL;
849 copy_siginfo(&q->info, info);
852 } else if (!is_si_special(info)) {
853 if (sig >= SIGRTMIN && info->si_code != SI_USER)
855 * Queue overflow, abort. We may abort if the signal was rt
856 * and sent by user using something other than kill().
862 signalfd_notify(t, sig);
863 sigaddset(&pending->signal, sig);
864 complete_signal(sig, t, group);
868 int print_fatal_signals;
870 static void print_fatal_signal(struct pt_regs *regs, int signr)
872 printk("%s/%d: potentially unexpected fatal signal %d.\n",
873 current->comm, task_pid_nr(current), signr);
875 #if defined(__i386__) && !defined(__arch_um__)
876 printk("code at %08lx: ", regs->ip);
879 for (i = 0; i < 16; i++) {
882 __get_user(insn, (unsigned char *)(regs->ip + i));
883 printk("%02x ", insn);
891 static int __init setup_print_fatal_signals(char *str)
893 get_option (&str, &print_fatal_signals);
898 __setup("print-fatal-signals=", setup_print_fatal_signals);
901 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
903 return send_signal(sig, info, p, 1);
907 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
909 return send_signal(sig, info, t, 0);
913 * Force a signal that the process can't ignore: if necessary
914 * we unblock the signal and change any SIG_IGN to SIG_DFL.
916 * Note: If we unblock the signal, we always reset it to SIG_DFL,
917 * since we do not want to have a signal handler that was blocked
918 * be invoked when user space had explicitly blocked it.
920 * We don't want to have recursive SIGSEGV's etc, for example,
921 * that is why we also clear SIGNAL_UNKILLABLE.
924 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
926 unsigned long int flags;
927 int ret, blocked, ignored;
928 struct k_sigaction *action;
930 spin_lock_irqsave(&t->sighand->siglock, flags);
931 action = &t->sighand->action[sig-1];
932 ignored = action->sa.sa_handler == SIG_IGN;
933 blocked = sigismember(&t->blocked, sig);
934 if (blocked || ignored) {
935 action->sa.sa_handler = SIG_DFL;
937 sigdelset(&t->blocked, sig);
938 recalc_sigpending_and_wake(t);
941 if (action->sa.sa_handler == SIG_DFL)
942 t->signal->flags &= ~SIGNAL_UNKILLABLE;
943 ret = specific_send_sig_info(sig, info, t);
944 spin_unlock_irqrestore(&t->sighand->siglock, flags);
950 force_sig_specific(int sig, struct task_struct *t)
952 force_sig_info(sig, SEND_SIG_FORCED, t);
956 * Nuke all other threads in the group.
958 void zap_other_threads(struct task_struct *p)
960 struct task_struct *t;
962 p->signal->group_stop_count = 0;
964 for (t = next_thread(p); t != p; t = next_thread(t)) {
966 * Don't bother with already dead threads
971 /* SIGKILL will be handled before any pending SIGSTOP */
972 sigaddset(&t->pending.signal, SIGKILL);
973 signal_wake_up(t, 1);
977 int __fatal_signal_pending(struct task_struct *tsk)
979 return sigismember(&tsk->pending.signal, SIGKILL);
981 EXPORT_SYMBOL(__fatal_signal_pending);
983 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
985 struct sighand_struct *sighand;
989 sighand = rcu_dereference(tsk->sighand);
990 if (unlikely(sighand == NULL))
993 spin_lock_irqsave(&sighand->siglock, *flags);
994 if (likely(sighand == tsk->sighand))
996 spin_unlock_irqrestore(&sighand->siglock, *flags);
1003 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1005 unsigned long flags;
1008 ret = check_kill_permission(sig, info, p);
1012 if (lock_task_sighand(p, &flags)) {
1013 ret = __group_send_sig_info(sig, info, p);
1014 unlock_task_sighand(p, &flags);
1022 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1023 * control characters do (^C, ^Z etc)
1026 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1028 struct task_struct *p = NULL;
1029 int retval, success;
1033 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1034 int err = group_send_sig_info(sig, info, p);
1037 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1038 return success ? 0 : retval;
1041 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1044 struct task_struct *p;
1048 p = pid_task(pid, PIDTYPE_PID);
1050 error = group_send_sig_info(sig, info, p);
1051 if (unlikely(error == -ESRCH))
1053 * The task was unhashed in between, try again.
1054 * If it is dead, pid_task() will return NULL,
1055 * if we race with de_thread() it will find the
1066 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1070 error = kill_pid_info(sig, info, find_vpid(pid));
1075 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1076 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1077 uid_t uid, uid_t euid, u32 secid)
1080 struct task_struct *p;
1082 if (!valid_signal(sig))
1085 read_lock(&tasklist_lock);
1086 p = pid_task(pid, PIDTYPE_PID);
1091 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1092 && (euid != p->suid) && (euid != p->uid)
1093 && (uid != p->suid) && (uid != p->uid)) {
1097 ret = security_task_kill(p, info, sig, secid);
1100 if (sig && p->sighand) {
1101 unsigned long flags;
1102 spin_lock_irqsave(&p->sighand->siglock, flags);
1103 ret = __group_send_sig_info(sig, info, p);
1104 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1107 read_unlock(&tasklist_lock);
1110 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1113 * kill_something_info() interprets pid in interesting ways just like kill(2).
1115 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1116 * is probably wrong. Should make it like BSD or SYSV.
1119 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1125 ret = kill_pid_info(sig, info, find_vpid(pid));
1130 read_lock(&tasklist_lock);
1132 ret = __kill_pgrp_info(sig, info,
1133 pid ? find_vpid(-pid) : task_pgrp(current));
1135 int retval = 0, count = 0;
1136 struct task_struct * p;
1138 for_each_process(p) {
1139 if (p->pid > 1 && !same_thread_group(p, current)) {
1140 int err = group_send_sig_info(sig, info, p);
1146 ret = count ? retval : -ESRCH;
1148 read_unlock(&tasklist_lock);
1154 * These are for backward compatibility with the rest of the kernel source.
1158 * The caller must ensure the task can't exit.
1161 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1164 unsigned long flags;
1167 * Make sure legacy kernel users don't send in bad values
1168 * (normal paths check this in check_kill_permission).
1170 if (!valid_signal(sig))
1173 spin_lock_irqsave(&p->sighand->siglock, flags);
1174 ret = specific_send_sig_info(sig, info, p);
1175 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1179 #define __si_special(priv) \
1180 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1183 send_sig(int sig, struct task_struct *p, int priv)
1185 return send_sig_info(sig, __si_special(priv), p);
1189 force_sig(int sig, struct task_struct *p)
1191 force_sig_info(sig, SEND_SIG_PRIV, p);
1195 * When things go south during signal handling, we
1196 * will force a SIGSEGV. And if the signal that caused
1197 * the problem was already a SIGSEGV, we'll want to
1198 * make sure we don't even try to deliver the signal..
1201 force_sigsegv(int sig, struct task_struct *p)
1203 if (sig == SIGSEGV) {
1204 unsigned long flags;
1205 spin_lock_irqsave(&p->sighand->siglock, flags);
1206 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1207 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1209 force_sig(SIGSEGV, p);
1213 int kill_pgrp(struct pid *pid, int sig, int priv)
1217 read_lock(&tasklist_lock);
1218 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1219 read_unlock(&tasklist_lock);
1223 EXPORT_SYMBOL(kill_pgrp);
1225 int kill_pid(struct pid *pid, int sig, int priv)
1227 return kill_pid_info(sig, __si_special(priv), pid);
1229 EXPORT_SYMBOL(kill_pid);
1232 * These functions support sending signals using preallocated sigqueue
1233 * structures. This is needed "because realtime applications cannot
1234 * afford to lose notifications of asynchronous events, like timer
1235 * expirations or I/O completions". In the case of Posix Timers
1236 * we allocate the sigqueue structure from the timer_create. If this
1237 * allocation fails we are able to report the failure to the application
1238 * with an EAGAIN error.
1241 struct sigqueue *sigqueue_alloc(void)
1245 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1246 q->flags |= SIGQUEUE_PREALLOC;
1250 void sigqueue_free(struct sigqueue *q)
1252 unsigned long flags;
1253 spinlock_t *lock = ¤t->sighand->siglock;
1255 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1257 * We must hold ->siglock while testing q->list
1258 * to serialize with collect_signal() or with
1259 * __exit_signal()->flush_sigqueue().
1261 spin_lock_irqsave(lock, flags);
1262 q->flags &= ~SIGQUEUE_PREALLOC;
1264 * If it is queued it will be freed when dequeued,
1265 * like the "regular" sigqueue.
1267 if (!list_empty(&q->list))
1269 spin_unlock_irqrestore(lock, flags);
1275 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1277 int sig = q->info.si_signo;
1278 struct sigpending *pending;
1279 unsigned long flags;
1282 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1285 if (!likely(lock_task_sighand(t, &flags)))
1288 ret = 1; /* the signal is ignored */
1289 if (!prepare_signal(sig, t))
1293 if (unlikely(!list_empty(&q->list))) {
1295 * If an SI_TIMER entry is already queue just increment
1296 * the overrun count.
1298 BUG_ON(q->info.si_code != SI_TIMER);
1299 q->info.si_overrun++;
1303 signalfd_notify(t, sig);
1304 pending = group ? &t->signal->shared_pending : &t->pending;
1305 list_add_tail(&q->list, &pending->list);
1306 sigaddset(&pending->signal, sig);
1307 complete_signal(sig, t, group);
1309 unlock_task_sighand(t, &flags);
1315 * Wake up any threads in the parent blocked in wait* syscalls.
1317 static inline void __wake_up_parent(struct task_struct *p,
1318 struct task_struct *parent)
1320 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1324 * Let a parent know about the death of a child.
1325 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1328 void do_notify_parent(struct task_struct *tsk, int sig)
1330 struct siginfo info;
1331 unsigned long flags;
1332 struct sighand_struct *psig;
1336 /* do_notify_parent_cldstop should have been called instead. */
1337 BUG_ON(task_is_stopped_or_traced(tsk));
1339 BUG_ON(!tsk->ptrace &&
1340 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1342 info.si_signo = sig;
1345 * we are under tasklist_lock here so our parent is tied to
1346 * us and cannot exit and release its namespace.
1348 * the only it can is to switch its nsproxy with sys_unshare,
1349 * bu uncharing pid namespaces is not allowed, so we'll always
1350 * see relevant namespace
1352 * write_lock() currently calls preempt_disable() which is the
1353 * same as rcu_read_lock(), but according to Oleg, this is not
1354 * correct to rely on this
1357 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1360 info.si_uid = tsk->uid;
1362 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1363 tsk->signal->utime));
1364 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1365 tsk->signal->stime));
1367 info.si_status = tsk->exit_code & 0x7f;
1368 if (tsk->exit_code & 0x80)
1369 info.si_code = CLD_DUMPED;
1370 else if (tsk->exit_code & 0x7f)
1371 info.si_code = CLD_KILLED;
1373 info.si_code = CLD_EXITED;
1374 info.si_status = tsk->exit_code >> 8;
1377 psig = tsk->parent->sighand;
1378 spin_lock_irqsave(&psig->siglock, flags);
1379 if (!tsk->ptrace && sig == SIGCHLD &&
1380 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1381 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1383 * We are exiting and our parent doesn't care. POSIX.1
1384 * defines special semantics for setting SIGCHLD to SIG_IGN
1385 * or setting the SA_NOCLDWAIT flag: we should be reaped
1386 * automatically and not left for our parent's wait4 call.
1387 * Rather than having the parent do it as a magic kind of
1388 * signal handler, we just set this to tell do_exit that we
1389 * can be cleaned up without becoming a zombie. Note that
1390 * we still call __wake_up_parent in this case, because a
1391 * blocked sys_wait4 might now return -ECHILD.
1393 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1394 * is implementation-defined: we do (if you don't want
1395 * it, just use SIG_IGN instead).
1397 tsk->exit_signal = -1;
1398 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1401 if (valid_signal(sig) && sig > 0)
1402 __group_send_sig_info(sig, &info, tsk->parent);
1403 __wake_up_parent(tsk, tsk->parent);
1404 spin_unlock_irqrestore(&psig->siglock, flags);
1407 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1409 struct siginfo info;
1410 unsigned long flags;
1411 struct task_struct *parent;
1412 struct sighand_struct *sighand;
1414 if (tsk->ptrace & PT_PTRACED)
1415 parent = tsk->parent;
1417 tsk = tsk->group_leader;
1418 parent = tsk->real_parent;
1421 info.si_signo = SIGCHLD;
1424 * see comment in do_notify_parent() abot the following 3 lines
1427 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1430 info.si_uid = tsk->uid;
1432 info.si_utime = cputime_to_clock_t(tsk->utime);
1433 info.si_stime = cputime_to_clock_t(tsk->stime);
1438 info.si_status = SIGCONT;
1441 info.si_status = tsk->signal->group_exit_code & 0x7f;
1444 info.si_status = tsk->exit_code & 0x7f;
1450 sighand = parent->sighand;
1451 spin_lock_irqsave(&sighand->siglock, flags);
1452 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1453 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1454 __group_send_sig_info(SIGCHLD, &info, parent);
1456 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1458 __wake_up_parent(tsk, parent);
1459 spin_unlock_irqrestore(&sighand->siglock, flags);
1462 static inline int may_ptrace_stop(void)
1464 if (!likely(current->ptrace & PT_PTRACED))
1467 * Are we in the middle of do_coredump?
1468 * If so and our tracer is also part of the coredump stopping
1469 * is a deadlock situation, and pointless because our tracer
1470 * is dead so don't allow us to stop.
1471 * If SIGKILL was already sent before the caller unlocked
1472 * ->siglock we must see ->core_state != NULL. Otherwise it
1473 * is safe to enter schedule().
1475 if (unlikely(current->mm->core_state) &&
1476 unlikely(current->mm == current->parent->mm))
1483 * Return nonzero if there is a SIGKILL that should be waking us up.
1484 * Called with the siglock held.
1486 static int sigkill_pending(struct task_struct *tsk)
1488 return sigismember(&tsk->pending.signal, SIGKILL) ||
1489 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1493 * This must be called with current->sighand->siglock held.
1495 * This should be the path for all ptrace stops.
1496 * We always set current->last_siginfo while stopped here.
1497 * That makes it a way to test a stopped process for
1498 * being ptrace-stopped vs being job-control-stopped.
1500 * If we actually decide not to stop at all because the tracer
1501 * is gone, we keep current->exit_code unless clear_code.
1503 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1505 if (arch_ptrace_stop_needed(exit_code, info)) {
1507 * The arch code has something special to do before a
1508 * ptrace stop. This is allowed to block, e.g. for faults
1509 * on user stack pages. We can't keep the siglock while
1510 * calling arch_ptrace_stop, so we must release it now.
1511 * To preserve proper semantics, we must do this before
1512 * any signal bookkeeping like checking group_stop_count.
1513 * Meanwhile, a SIGKILL could come in before we retake the
1514 * siglock. That must prevent us from sleeping in TASK_TRACED.
1515 * So after regaining the lock, we must check for SIGKILL.
1517 spin_unlock_irq(¤t->sighand->siglock);
1518 arch_ptrace_stop(exit_code, info);
1519 spin_lock_irq(¤t->sighand->siglock);
1520 if (sigkill_pending(current))
1525 * If there is a group stop in progress,
1526 * we must participate in the bookkeeping.
1528 if (current->signal->group_stop_count > 0)
1529 --current->signal->group_stop_count;
1531 current->last_siginfo = info;
1532 current->exit_code = exit_code;
1534 /* Let the debugger run. */
1535 __set_current_state(TASK_TRACED);
1536 spin_unlock_irq(¤t->sighand->siglock);
1537 read_lock(&tasklist_lock);
1538 if (may_ptrace_stop()) {
1539 do_notify_parent_cldstop(current, CLD_TRAPPED);
1540 read_unlock(&tasklist_lock);
1544 * By the time we got the lock, our tracer went away.
1545 * Don't drop the lock yet, another tracer may come.
1547 __set_current_state(TASK_RUNNING);
1549 current->exit_code = 0;
1550 read_unlock(&tasklist_lock);
1554 * While in TASK_TRACED, we were considered "frozen enough".
1555 * Now that we woke up, it's crucial if we're supposed to be
1556 * frozen that we freeze now before running anything substantial.
1561 * We are back. Now reacquire the siglock before touching
1562 * last_siginfo, so that we are sure to have synchronized with
1563 * any signal-sending on another CPU that wants to examine it.
1565 spin_lock_irq(¤t->sighand->siglock);
1566 current->last_siginfo = NULL;
1569 * Queued signals ignored us while we were stopped for tracing.
1570 * So check for any that we should take before resuming user mode.
1571 * This sets TIF_SIGPENDING, but never clears it.
1573 recalc_sigpending_tsk(current);
1576 void ptrace_notify(int exit_code)
1580 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1582 memset(&info, 0, sizeof info);
1583 info.si_signo = SIGTRAP;
1584 info.si_code = exit_code;
1585 info.si_pid = task_pid_vnr(current);
1586 info.si_uid = current->uid;
1588 /* Let the debugger run. */
1589 spin_lock_irq(¤t->sighand->siglock);
1590 ptrace_stop(exit_code, 1, &info);
1591 spin_unlock_irq(¤t->sighand->siglock);
1595 finish_stop(int stop_count)
1598 * If there are no other threads in the group, or if there is
1599 * a group stop in progress and we are the last to stop,
1600 * report to the parent. When ptraced, every thread reports itself.
1602 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1603 read_lock(&tasklist_lock);
1604 do_notify_parent_cldstop(current, CLD_STOPPED);
1605 read_unlock(&tasklist_lock);
1610 } while (try_to_freeze());
1612 * Now we don't run again until continued.
1614 current->exit_code = 0;
1618 * This performs the stopping for SIGSTOP and other stop signals.
1619 * We have to stop all threads in the thread group.
1620 * Returns nonzero if we've actually stopped and released the siglock.
1621 * Returns zero if we didn't stop and still hold the siglock.
1623 static int do_signal_stop(int signr)
1625 struct signal_struct *sig = current->signal;
1628 if (sig->group_stop_count > 0) {
1630 * There is a group stop in progress. We don't need to
1631 * start another one.
1633 stop_count = --sig->group_stop_count;
1635 struct task_struct *t;
1637 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1638 unlikely(signal_group_exit(sig)))
1641 * There is no group stop already in progress.
1642 * We must initiate one now.
1644 sig->group_exit_code = signr;
1647 for (t = next_thread(current); t != current; t = next_thread(t))
1649 * Setting state to TASK_STOPPED for a group
1650 * stop is always done with the siglock held,
1651 * so this check has no races.
1653 if (!(t->flags & PF_EXITING) &&
1654 !task_is_stopped_or_traced(t)) {
1656 signal_wake_up(t, 0);
1658 sig->group_stop_count = stop_count;
1661 if (stop_count == 0)
1662 sig->flags = SIGNAL_STOP_STOPPED;
1663 current->exit_code = sig->group_exit_code;
1664 __set_current_state(TASK_STOPPED);
1666 spin_unlock_irq(¤t->sighand->siglock);
1667 finish_stop(stop_count);
1671 static int ptrace_signal(int signr, siginfo_t *info,
1672 struct pt_regs *regs, void *cookie)
1674 if (!(current->ptrace & PT_PTRACED))
1677 ptrace_signal_deliver(regs, cookie);
1679 /* Let the debugger run. */
1680 ptrace_stop(signr, 0, info);
1682 /* We're back. Did the debugger cancel the sig? */
1683 signr = current->exit_code;
1687 current->exit_code = 0;
1689 /* Update the siginfo structure if the signal has
1690 changed. If the debugger wanted something
1691 specific in the siginfo structure then it should
1692 have updated *info via PTRACE_SETSIGINFO. */
1693 if (signr != info->si_signo) {
1694 info->si_signo = signr;
1696 info->si_code = SI_USER;
1697 info->si_pid = task_pid_vnr(current->parent);
1698 info->si_uid = current->parent->uid;
1701 /* If the (new) signal is now blocked, requeue it. */
1702 if (sigismember(¤t->blocked, signr)) {
1703 specific_send_sig_info(signr, info, current);
1710 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1711 struct pt_regs *regs, void *cookie)
1713 struct sighand_struct *sighand = current->sighand;
1714 struct signal_struct *signal = current->signal;
1719 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1720 * While in TASK_STOPPED, we were considered "frozen enough".
1721 * Now that we woke up, it's crucial if we're supposed to be
1722 * frozen that we freeze now before running anything substantial.
1726 spin_lock_irq(&sighand->siglock);
1728 * Every stopped thread goes here after wakeup. Check to see if
1729 * we should notify the parent, prepare_signal(SIGCONT) encodes
1730 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1732 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1733 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1734 ? CLD_CONTINUED : CLD_STOPPED;
1735 signal->flags &= ~SIGNAL_CLD_MASK;
1736 spin_unlock_irq(&sighand->siglock);
1738 read_lock(&tasklist_lock);
1739 do_notify_parent_cldstop(current->group_leader, why);
1740 read_unlock(&tasklist_lock);
1745 struct k_sigaction *ka;
1747 if (unlikely(signal->group_stop_count > 0) &&
1751 signr = dequeue_signal(current, ¤t->blocked, info);
1753 break; /* will return 0 */
1755 if (signr != SIGKILL) {
1756 signr = ptrace_signal(signr, info, regs, cookie);
1761 ka = &sighand->action[signr-1];
1762 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1764 if (ka->sa.sa_handler != SIG_DFL) {
1765 /* Run the handler. */
1768 if (ka->sa.sa_flags & SA_ONESHOT)
1769 ka->sa.sa_handler = SIG_DFL;
1771 break; /* will return non-zero "signr" value */
1775 * Now we are doing the default action for this signal.
1777 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1781 * Global init gets no signals it doesn't want.
1783 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1784 !signal_group_exit(signal))
1787 if (sig_kernel_stop(signr)) {
1789 * The default action is to stop all threads in
1790 * the thread group. The job control signals
1791 * do nothing in an orphaned pgrp, but SIGSTOP
1792 * always works. Note that siglock needs to be
1793 * dropped during the call to is_orphaned_pgrp()
1794 * because of lock ordering with tasklist_lock.
1795 * This allows an intervening SIGCONT to be posted.
1796 * We need to check for that and bail out if necessary.
1798 if (signr != SIGSTOP) {
1799 spin_unlock_irq(&sighand->siglock);
1801 /* signals can be posted during this window */
1803 if (is_current_pgrp_orphaned())
1806 spin_lock_irq(&sighand->siglock);
1809 if (likely(do_signal_stop(signr))) {
1810 /* It released the siglock. */
1815 * We didn't actually stop, due to a race
1816 * with SIGCONT or something like that.
1821 spin_unlock_irq(&sighand->siglock);
1824 * Anything else is fatal, maybe with a core dump.
1826 current->flags |= PF_SIGNALED;
1828 if (sig_kernel_coredump(signr)) {
1829 if (print_fatal_signals)
1830 print_fatal_signal(regs, signr);
1832 * If it was able to dump core, this kills all
1833 * other threads in the group and synchronizes with
1834 * their demise. If we lost the race with another
1835 * thread getting here, it set group_exit_code
1836 * first and our do_group_exit call below will use
1837 * that value and ignore the one we pass it.
1839 do_coredump((long)signr, signr, regs);
1843 * Death signals, no core dump.
1845 do_group_exit(signr);
1848 spin_unlock_irq(&sighand->siglock);
1852 void exit_signals(struct task_struct *tsk)
1855 struct task_struct *t;
1857 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1858 tsk->flags |= PF_EXITING;
1862 spin_lock_irq(&tsk->sighand->siglock);
1864 * From now this task is not visible for group-wide signals,
1865 * see wants_signal(), do_signal_stop().
1867 tsk->flags |= PF_EXITING;
1868 if (!signal_pending(tsk))
1871 /* It could be that __group_complete_signal() choose us to
1872 * notify about group-wide signal. Another thread should be
1873 * woken now to take the signal since we will not.
1875 for (t = tsk; (t = next_thread(t)) != tsk; )
1876 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1877 recalc_sigpending_and_wake(t);
1879 if (unlikely(tsk->signal->group_stop_count) &&
1880 !--tsk->signal->group_stop_count) {
1881 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1885 spin_unlock_irq(&tsk->sighand->siglock);
1887 if (unlikely(group_stop)) {
1888 read_lock(&tasklist_lock);
1889 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1890 read_unlock(&tasklist_lock);
1894 EXPORT_SYMBOL(recalc_sigpending);
1895 EXPORT_SYMBOL_GPL(dequeue_signal);
1896 EXPORT_SYMBOL(flush_signals);
1897 EXPORT_SYMBOL(force_sig);
1898 EXPORT_SYMBOL(send_sig);
1899 EXPORT_SYMBOL(send_sig_info);
1900 EXPORT_SYMBOL(sigprocmask);
1901 EXPORT_SYMBOL(block_all_signals);
1902 EXPORT_SYMBOL(unblock_all_signals);
1906 * System call entry points.
1909 asmlinkage long sys_restart_syscall(void)
1911 struct restart_block *restart = ¤t_thread_info()->restart_block;
1912 return restart->fn(restart);
1915 long do_no_restart_syscall(struct restart_block *param)
1921 * We don't need to get the kernel lock - this is all local to this
1922 * particular thread.. (and that's good, because this is _heavily_
1923 * used by various programs)
1927 * This is also useful for kernel threads that want to temporarily
1928 * (or permanently) block certain signals.
1930 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1931 * interface happily blocks "unblockable" signals like SIGKILL
1934 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1938 spin_lock_irq(¤t->sighand->siglock);
1940 *oldset = current->blocked;
1945 sigorsets(¤t->blocked, ¤t->blocked, set);
1948 signandsets(¤t->blocked, ¤t->blocked, set);
1951 current->blocked = *set;
1956 recalc_sigpending();
1957 spin_unlock_irq(¤t->sighand->siglock);
1963 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1965 int error = -EINVAL;
1966 sigset_t old_set, new_set;
1968 /* XXX: Don't preclude handling different sized sigset_t's. */
1969 if (sigsetsize != sizeof(sigset_t))
1974 if (copy_from_user(&new_set, set, sizeof(*set)))
1976 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1978 error = sigprocmask(how, &new_set, &old_set);
1984 spin_lock_irq(¤t->sighand->siglock);
1985 old_set = current->blocked;
1986 spin_unlock_irq(¤t->sighand->siglock);
1990 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1998 long do_sigpending(void __user *set, unsigned long sigsetsize)
2000 long error = -EINVAL;
2003 if (sigsetsize > sizeof(sigset_t))
2006 spin_lock_irq(¤t->sighand->siglock);
2007 sigorsets(&pending, ¤t->pending.signal,
2008 ¤t->signal->shared_pending.signal);
2009 spin_unlock_irq(¤t->sighand->siglock);
2011 /* Outside the lock because only this thread touches it. */
2012 sigandsets(&pending, ¤t->blocked, &pending);
2015 if (!copy_to_user(set, &pending, sigsetsize))
2023 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2025 return do_sigpending(set, sigsetsize);
2028 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2030 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2034 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2036 if (from->si_code < 0)
2037 return __copy_to_user(to, from, sizeof(siginfo_t))
2040 * If you change siginfo_t structure, please be sure
2041 * this code is fixed accordingly.
2042 * Please remember to update the signalfd_copyinfo() function
2043 * inside fs/signalfd.c too, in case siginfo_t changes.
2044 * It should never copy any pad contained in the structure
2045 * to avoid security leaks, but must copy the generic
2046 * 3 ints plus the relevant union member.
2048 err = __put_user(from->si_signo, &to->si_signo);
2049 err |= __put_user(from->si_errno, &to->si_errno);
2050 err |= __put_user((short)from->si_code, &to->si_code);
2051 switch (from->si_code & __SI_MASK) {
2053 err |= __put_user(from->si_pid, &to->si_pid);
2054 err |= __put_user(from->si_uid, &to->si_uid);
2057 err |= __put_user(from->si_tid, &to->si_tid);
2058 err |= __put_user(from->si_overrun, &to->si_overrun);
2059 err |= __put_user(from->si_ptr, &to->si_ptr);
2062 err |= __put_user(from->si_band, &to->si_band);
2063 err |= __put_user(from->si_fd, &to->si_fd);
2066 err |= __put_user(from->si_addr, &to->si_addr);
2067 #ifdef __ARCH_SI_TRAPNO
2068 err |= __put_user(from->si_trapno, &to->si_trapno);
2072 err |= __put_user(from->si_pid, &to->si_pid);
2073 err |= __put_user(from->si_uid, &to->si_uid);
2074 err |= __put_user(from->si_status, &to->si_status);
2075 err |= __put_user(from->si_utime, &to->si_utime);
2076 err |= __put_user(from->si_stime, &to->si_stime);
2078 case __SI_RT: /* This is not generated by the kernel as of now. */
2079 case __SI_MESGQ: /* But this is */
2080 err |= __put_user(from->si_pid, &to->si_pid);
2081 err |= __put_user(from->si_uid, &to->si_uid);
2082 err |= __put_user(from->si_ptr, &to->si_ptr);
2084 default: /* this is just in case for now ... */
2085 err |= __put_user(from->si_pid, &to->si_pid);
2086 err |= __put_user(from->si_uid, &to->si_uid);
2095 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2096 siginfo_t __user *uinfo,
2097 const struct timespec __user *uts,
2106 /* XXX: Don't preclude handling different sized sigset_t's. */
2107 if (sigsetsize != sizeof(sigset_t))
2110 if (copy_from_user(&these, uthese, sizeof(these)))
2114 * Invert the set of allowed signals to get those we
2117 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2121 if (copy_from_user(&ts, uts, sizeof(ts)))
2123 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2128 spin_lock_irq(¤t->sighand->siglock);
2129 sig = dequeue_signal(current, &these, &info);
2131 timeout = MAX_SCHEDULE_TIMEOUT;
2133 timeout = (timespec_to_jiffies(&ts)
2134 + (ts.tv_sec || ts.tv_nsec));
2137 /* None ready -- temporarily unblock those we're
2138 * interested while we are sleeping in so that we'll
2139 * be awakened when they arrive. */
2140 current->real_blocked = current->blocked;
2141 sigandsets(¤t->blocked, ¤t->blocked, &these);
2142 recalc_sigpending();
2143 spin_unlock_irq(¤t->sighand->siglock);
2145 timeout = schedule_timeout_interruptible(timeout);
2147 spin_lock_irq(¤t->sighand->siglock);
2148 sig = dequeue_signal(current, &these, &info);
2149 current->blocked = current->real_blocked;
2150 siginitset(¤t->real_blocked, 0);
2151 recalc_sigpending();
2154 spin_unlock_irq(¤t->sighand->siglock);
2159 if (copy_siginfo_to_user(uinfo, &info))
2172 sys_kill(pid_t pid, int sig)
2174 struct siginfo info;
2176 info.si_signo = sig;
2178 info.si_code = SI_USER;
2179 info.si_pid = task_tgid_vnr(current);
2180 info.si_uid = current->uid;
2182 return kill_something_info(sig, &info, pid);
2185 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2188 struct siginfo info;
2189 struct task_struct *p;
2190 unsigned long flags;
2193 info.si_signo = sig;
2195 info.si_code = SI_TKILL;
2196 info.si_pid = task_tgid_vnr(current);
2197 info.si_uid = current->uid;
2200 p = find_task_by_vpid(pid);
2201 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2202 error = check_kill_permission(sig, &info, p);
2204 * The null signal is a permissions and process existence
2205 * probe. No signal is actually delivered.
2207 * If lock_task_sighand() fails we pretend the task dies
2208 * after receiving the signal. The window is tiny, and the
2209 * signal is private anyway.
2211 if (!error && sig && lock_task_sighand(p, &flags)) {
2212 error = specific_send_sig_info(sig, &info, p);
2213 unlock_task_sighand(p, &flags);
2222 * sys_tgkill - send signal to one specific thread
2223 * @tgid: the thread group ID of the thread
2224 * @pid: the PID of the thread
2225 * @sig: signal to be sent
2227 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2228 * exists but it's not belonging to the target process anymore. This
2229 * method solves the problem of threads exiting and PIDs getting reused.
2231 asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig)
2233 /* This is only valid for single tasks */
2234 if (pid <= 0 || tgid <= 0)
2237 return do_tkill(tgid, pid, sig);
2241 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2244 sys_tkill(pid_t pid, int sig)
2246 /* This is only valid for single tasks */
2250 return do_tkill(0, pid, sig);
2254 sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo)
2258 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2261 /* Not even root can pretend to send signals from the kernel.
2262 Nor can they impersonate a kill(), which adds source info. */
2263 if (info.si_code >= 0)
2265 info.si_signo = sig;
2267 /* POSIX.1b doesn't mention process groups. */
2268 return kill_proc_info(sig, &info, pid);
2271 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2273 struct task_struct *t = current;
2274 struct k_sigaction *k;
2277 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2280 k = &t->sighand->action[sig-1];
2282 spin_lock_irq(¤t->sighand->siglock);
2287 sigdelsetmask(&act->sa.sa_mask,
2288 sigmask(SIGKILL) | sigmask(SIGSTOP));
2292 * "Setting a signal action to SIG_IGN for a signal that is
2293 * pending shall cause the pending signal to be discarded,
2294 * whether or not it is blocked."
2296 * "Setting a signal action to SIG_DFL for a signal that is
2297 * pending and whose default action is to ignore the signal
2298 * (for example, SIGCHLD), shall cause the pending signal to
2299 * be discarded, whether or not it is blocked"
2301 if (__sig_ignored(t, sig)) {
2303 sigaddset(&mask, sig);
2304 rm_from_queue_full(&mask, &t->signal->shared_pending);
2306 rm_from_queue_full(&mask, &t->pending);
2308 } while (t != current);
2312 spin_unlock_irq(¤t->sighand->siglock);
2317 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2323 oss.ss_sp = (void __user *) current->sas_ss_sp;
2324 oss.ss_size = current->sas_ss_size;
2325 oss.ss_flags = sas_ss_flags(sp);
2334 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2335 || __get_user(ss_sp, &uss->ss_sp)
2336 || __get_user(ss_flags, &uss->ss_flags)
2337 || __get_user(ss_size, &uss->ss_size))
2341 if (on_sig_stack(sp))
2347 * Note - this code used to test ss_flags incorrectly
2348 * old code may have been written using ss_flags==0
2349 * to mean ss_flags==SS_ONSTACK (as this was the only
2350 * way that worked) - this fix preserves that older
2353 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2356 if (ss_flags == SS_DISABLE) {
2361 if (ss_size < MINSIGSTKSZ)
2365 current->sas_ss_sp = (unsigned long) ss_sp;
2366 current->sas_ss_size = ss_size;
2371 if (copy_to_user(uoss, &oss, sizeof(oss)))
2380 #ifdef __ARCH_WANT_SYS_SIGPENDING
2383 sys_sigpending(old_sigset_t __user *set)
2385 return do_sigpending(set, sizeof(*set));
2390 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2391 /* Some platforms have their own version with special arguments others
2392 support only sys_rt_sigprocmask. */
2395 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2398 old_sigset_t old_set, new_set;
2402 if (copy_from_user(&new_set, set, sizeof(*set)))
2404 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2406 spin_lock_irq(¤t->sighand->siglock);
2407 old_set = current->blocked.sig[0];
2415 sigaddsetmask(¤t->blocked, new_set);
2418 sigdelsetmask(¤t->blocked, new_set);
2421 current->blocked.sig[0] = new_set;
2425 recalc_sigpending();
2426 spin_unlock_irq(¤t->sighand->siglock);
2432 old_set = current->blocked.sig[0];
2435 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2442 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2444 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2446 sys_rt_sigaction(int sig,
2447 const struct sigaction __user *act,
2448 struct sigaction __user *oact,
2451 struct k_sigaction new_sa, old_sa;
2454 /* XXX: Don't preclude handling different sized sigset_t's. */
2455 if (sigsetsize != sizeof(sigset_t))
2459 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2463 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2466 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2472 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2474 #ifdef __ARCH_WANT_SYS_SGETMASK
2477 * For backwards compatibility. Functionality superseded by sigprocmask.
2483 return current->blocked.sig[0];
2487 sys_ssetmask(int newmask)
2491 spin_lock_irq(¤t->sighand->siglock);
2492 old = current->blocked.sig[0];
2494 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2496 recalc_sigpending();
2497 spin_unlock_irq(¤t->sighand->siglock);
2501 #endif /* __ARCH_WANT_SGETMASK */
2503 #ifdef __ARCH_WANT_SYS_SIGNAL
2505 * For backwards compatibility. Functionality superseded by sigaction.
2507 asmlinkage unsigned long
2508 sys_signal(int sig, __sighandler_t handler)
2510 struct k_sigaction new_sa, old_sa;
2513 new_sa.sa.sa_handler = handler;
2514 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2515 sigemptyset(&new_sa.sa.sa_mask);
2517 ret = do_sigaction(sig, &new_sa, &old_sa);
2519 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2521 #endif /* __ARCH_WANT_SYS_SIGNAL */
2523 #ifdef __ARCH_WANT_SYS_PAUSE
2528 current->state = TASK_INTERRUPTIBLE;
2530 return -ERESTARTNOHAND;
2535 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2536 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2540 /* XXX: Don't preclude handling different sized sigset_t's. */
2541 if (sigsetsize != sizeof(sigset_t))
2544 if (copy_from_user(&newset, unewset, sizeof(newset)))
2546 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2548 spin_lock_irq(¤t->sighand->siglock);
2549 current->saved_sigmask = current->blocked;
2550 current->blocked = newset;
2551 recalc_sigpending();
2552 spin_unlock_irq(¤t->sighand->siglock);
2554 current->state = TASK_INTERRUPTIBLE;
2556 set_restore_sigmask();
2557 return -ERESTARTNOHAND;
2559 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2561 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2566 void __init signals_init(void)
2568 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);