2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache *sigqueue_cachep;
42 static int __sig_ignored(struct task_struct *t, int sig)
46 /* Is it explicitly or implicitly ignored? */
48 handler = t->sighand->action[sig - 1].sa.sa_handler;
49 return handler == SIG_IGN ||
50 (handler == SIG_DFL && sig_kernel_ignore(sig));
53 static int sig_ignored(struct task_struct *t, int sig)
56 * Tracers always want to know about signals..
58 if (t->ptrace & PT_PTRACED)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
69 return __sig_ignored(t, sig);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
81 switch (_NSIG_WORDS) {
83 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
84 ready |= signal->sig[i] &~ blocked->sig[i];
87 case 4: ready = signal->sig[3] &~ blocked->sig[3];
88 ready |= signal->sig[2] &~ blocked->sig[2];
89 ready |= signal->sig[1] &~ blocked->sig[1];
90 ready |= signal->sig[0] &~ blocked->sig[0];
93 case 2: ready = signal->sig[1] &~ blocked->sig[1];
94 ready |= signal->sig[0] &~ blocked->sig[0];
97 case 1: ready = signal->sig[0] &~ blocked->sig[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct *t)
106 if (t->signal->group_stop_count > 0 ||
107 PENDING(&t->pending, &t->blocked) ||
108 PENDING(&t->signal->shared_pending, &t->blocked)) {
109 set_tsk_thread_flag(t, TIF_SIGPENDING);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct *t)
126 if (recalc_sigpending_tsk(t))
127 signal_wake_up(t, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current) && !freezing(current))
133 clear_thread_flag(TIF_SIGPENDING);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending *pending, sigset_t *mask)
141 unsigned long i, *s, *m, x;
144 s = pending->signal.sig;
146 switch (_NSIG_WORDS) {
148 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
149 if ((x = *s &~ *m) != 0) {
150 sig = ffz(~x) + i*_NSIG_BPW + 1;
155 case 2: if ((x = s[0] &~ m[0]) != 0)
157 else if ((x = s[1] &~ m[1]) != 0)
164 case 1: if ((x = *s &~ *m) != 0)
172 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
175 struct sigqueue *q = NULL;
176 struct user_struct *user;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user->sigpending);
185 if (override_rlimit ||
186 atomic_read(&user->sigpending) <=
187 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
188 q = kmem_cache_alloc(sigqueue_cachep, flags);
189 if (unlikely(q == NULL)) {
190 atomic_dec(&user->sigpending);
192 INIT_LIST_HEAD(&q->list);
194 q->user = get_uid(user);
199 static void __sigqueue_free(struct sigqueue *q)
201 if (q->flags & SIGQUEUE_PREALLOC)
203 atomic_dec(&q->user->sigpending);
205 kmem_cache_free(sigqueue_cachep, q);
208 void flush_sigqueue(struct sigpending *queue)
212 sigemptyset(&queue->signal);
213 while (!list_empty(&queue->list)) {
214 q = list_entry(queue->list.next, struct sigqueue , list);
215 list_del_init(&q->list);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct *t)
227 spin_lock_irqsave(&t->sighand->siglock, flags);
228 clear_tsk_thread_flag(t, TIF_SIGPENDING);
229 flush_sigqueue(&t->pending);
230 flush_sigqueue(&t->signal->shared_pending);
231 spin_unlock_irqrestore(&t->sighand->siglock, flags);
234 void ignore_signals(struct task_struct *t)
238 for (i = 0; i < _NSIG; ++i)
239 t->sighand->action[i].sa.sa_handler = SIG_IGN;
245 * Flush all handlers for a task.
249 flush_signal_handlers(struct task_struct *t, int force_default)
252 struct k_sigaction *ka = &t->sighand->action[0];
253 for (i = _NSIG ; i != 0 ; i--) {
254 if (force_default || ka->sa.sa_handler != SIG_IGN)
255 ka->sa.sa_handler = SIG_DFL;
257 sigemptyset(&ka->sa.sa_mask);
262 int unhandled_signal(struct task_struct *tsk, int sig)
264 if (is_global_init(tsk))
266 if (tsk->ptrace & PT_PTRACED)
268 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
269 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
273 /* Notify the system that a driver wants to block all signals for this
274 * process, and wants to be notified if any signals at all were to be
275 * sent/acted upon. If the notifier routine returns non-zero, then the
276 * signal will be acted upon after all. If the notifier routine returns 0,
277 * then then signal will be blocked. Only one block per process is
278 * allowed. priv is a pointer to private data that the notifier routine
279 * can use to determine if the signal should be blocked or not. */
282 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
286 spin_lock_irqsave(¤t->sighand->siglock, flags);
287 current->notifier_mask = mask;
288 current->notifier_data = priv;
289 current->notifier = notifier;
290 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
293 /* Notify the system that blocking has ended. */
296 unblock_all_signals(void)
300 spin_lock_irqsave(¤t->sighand->siglock, flags);
301 current->notifier = NULL;
302 current->notifier_data = NULL;
304 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
307 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
309 struct sigqueue *q, *first = NULL;
310 int still_pending = 0;
312 if (unlikely(!sigismember(&list->signal, sig)))
316 * Collect the siginfo appropriate to this signal. Check if
317 * there is another siginfo for the same signal.
319 list_for_each_entry(q, &list->list, list) {
320 if (q->info.si_signo == sig) {
329 list_del_init(&first->list);
330 copy_siginfo(info, &first->info);
331 __sigqueue_free(first);
333 sigdelset(&list->signal, sig);
336 /* Ok, it wasn't in the queue. This must be
337 a fast-pathed signal or we must have been
338 out of queue space. So zero out the info.
340 sigdelset(&list->signal, sig);
341 info->si_signo = sig;
350 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
353 int sig = next_signal(pending, mask);
356 if (current->notifier) {
357 if (sigismember(current->notifier_mask, sig)) {
358 if (!(current->notifier)(current->notifier_data)) {
359 clear_thread_flag(TIF_SIGPENDING);
365 if (!collect_signal(sig, pending, info))
373 * Dequeue a signal and return the element to the caller, which is
374 * expected to free it.
376 * All callers have to hold the siglock.
378 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
382 /* We only dequeue private signals from ourselves, we don't let
383 * signalfd steal them
385 signr = __dequeue_signal(&tsk->pending, mask, info);
387 signr = __dequeue_signal(&tsk->signal->shared_pending,
392 * itimers are process shared and we restart periodic
393 * itimers in the signal delivery path to prevent DoS
394 * attacks in the high resolution timer case. This is
395 * compliant with the old way of self restarting
396 * itimers, as the SIGALRM is a legacy signal and only
397 * queued once. Changing the restart behaviour to
398 * restart the timer in the signal dequeue path is
399 * reducing the timer noise on heavy loaded !highres
402 if (unlikely(signr == SIGALRM)) {
403 struct hrtimer *tmr = &tsk->signal->real_timer;
405 if (!hrtimer_is_queued(tmr) &&
406 tsk->signal->it_real_incr.tv64 != 0) {
407 hrtimer_forward(tmr, tmr->base->get_time(),
408 tsk->signal->it_real_incr);
409 hrtimer_restart(tmr);
418 if (unlikely(sig_kernel_stop(signr))) {
420 * Set a marker that we have dequeued a stop signal. Our
421 * caller might release the siglock and then the pending
422 * stop signal it is about to process is no longer in the
423 * pending bitmasks, but must still be cleared by a SIGCONT
424 * (and overruled by a SIGKILL). So those cases clear this
425 * shared flag after we've set it. Note that this flag may
426 * remain set after the signal we return is ignored or
427 * handled. That doesn't matter because its only purpose
428 * is to alert stop-signal processing code when another
429 * processor has come along and cleared the flag.
431 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
432 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
434 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
436 * Release the siglock to ensure proper locking order
437 * of timer locks outside of siglocks. Note, we leave
438 * irqs disabled here, since the posix-timers code is
439 * about to disable them again anyway.
441 spin_unlock(&tsk->sighand->siglock);
442 do_schedule_next_timer(info);
443 spin_lock(&tsk->sighand->siglock);
449 * Tell a process that it has a new active signal..
451 * NOTE! we rely on the previous spin_lock to
452 * lock interrupts for us! We can only be called with
453 * "siglock" held, and the local interrupt must
454 * have been disabled when that got acquired!
456 * No need to set need_resched since signal event passing
457 * goes through ->blocked
459 void signal_wake_up(struct task_struct *t, int resume)
463 set_tsk_thread_flag(t, TIF_SIGPENDING);
466 * For SIGKILL, we want to wake it up in the stopped/traced/killable
467 * case. We don't check t->state here because there is a race with it
468 * executing another processor and just now entering stopped state.
469 * By using wake_up_state, we ensure the process will wake up and
470 * handle its death signal.
472 mask = TASK_INTERRUPTIBLE;
474 mask |= TASK_WAKEKILL;
475 if (!wake_up_state(t, mask))
480 * Remove signals in mask from the pending set and queue.
481 * Returns 1 if any signals were found.
483 * All callers must be holding the siglock.
485 * This version takes a sigset mask and looks at all signals,
486 * not just those in the first mask word.
488 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
490 struct sigqueue *q, *n;
493 sigandsets(&m, mask, &s->signal);
494 if (sigisemptyset(&m))
497 signandsets(&s->signal, &s->signal, mask);
498 list_for_each_entry_safe(q, n, &s->list, list) {
499 if (sigismember(mask, q->info.si_signo)) {
500 list_del_init(&q->list);
507 * Remove signals in mask from the pending set and queue.
508 * Returns 1 if any signals were found.
510 * All callers must be holding the siglock.
512 static int rm_from_queue(unsigned long mask, struct sigpending *s)
514 struct sigqueue *q, *n;
516 if (!sigtestsetmask(&s->signal, mask))
519 sigdelsetmask(&s->signal, mask);
520 list_for_each_entry_safe(q, n, &s->list, list) {
521 if (q->info.si_signo < SIGRTMIN &&
522 (mask & sigmask(q->info.si_signo))) {
523 list_del_init(&q->list);
531 * Bad permissions for sending the signal
533 static int check_kill_permission(int sig, struct siginfo *info,
534 struct task_struct *t)
539 if (!valid_signal(sig))
542 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
545 error = audit_signal_info(sig, t); /* Let audit system see the signal */
549 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
550 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
551 !capable(CAP_KILL)) {
554 sid = task_session(t);
556 * We don't return the error if sid == NULL. The
557 * task was unhashed, the caller must notice this.
559 if (!sid || sid == task_session(current))
566 return security_task_kill(t, info, sig, 0);
570 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
573 * Handle magic process-wide effects of stop/continue signals. Unlike
574 * the signal actions, these happen immediately at signal-generation
575 * time regardless of blocking, ignoring, or handling. This does the
576 * actual continuing for SIGCONT, but not the actual stopping for stop
577 * signals. The process stop is done as a signal action for SIG_DFL.
579 * Returns true if the signal should be actually delivered, otherwise
580 * it should be dropped.
582 static int prepare_signal(int sig, struct task_struct *p)
584 struct signal_struct *signal = p->signal;
585 struct task_struct *t;
587 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
589 * The process is in the middle of dying, nothing to do.
591 } else if (sig_kernel_stop(sig)) {
593 * This is a stop signal. Remove SIGCONT from all queues.
595 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
598 rm_from_queue(sigmask(SIGCONT), &t->pending);
599 } while_each_thread(p, t);
600 } else if (sig == SIGCONT) {
603 * Remove all stop signals from all queues,
604 * and wake all threads.
606 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
610 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
612 * If there is a handler for SIGCONT, we must make
613 * sure that no thread returns to user mode before
614 * we post the signal, in case it was the only
615 * thread eligible to run the signal handler--then
616 * it must not do anything between resuming and
617 * running the handler. With the TIF_SIGPENDING
618 * flag set, the thread will pause and acquire the
619 * siglock that we hold now and until we've queued
620 * the pending signal.
622 * Wake up the stopped thread _after_ setting
625 state = __TASK_STOPPED;
626 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
627 set_tsk_thread_flag(t, TIF_SIGPENDING);
628 state |= TASK_INTERRUPTIBLE;
630 wake_up_state(t, state);
631 } while_each_thread(p, t);
634 * Notify the parent with CLD_CONTINUED if we were stopped.
636 * If we were in the middle of a group stop, we pretend it
637 * was already finished, and then continued. Since SIGCHLD
638 * doesn't queue we report only CLD_STOPPED, as if the next
639 * CLD_CONTINUED was dropped.
642 if (signal->flags & SIGNAL_STOP_STOPPED)
643 why |= SIGNAL_CLD_CONTINUED;
644 else if (signal->group_stop_count)
645 why |= SIGNAL_CLD_STOPPED;
649 * The first thread which returns from finish_stop()
650 * will take ->siglock, notice SIGNAL_CLD_MASK, and
651 * notify its parent. See get_signal_to_deliver().
653 signal->flags = why | SIGNAL_STOP_CONTINUED;
654 signal->group_stop_count = 0;
655 signal->group_exit_code = 0;
658 * We are not stopped, but there could be a stop
659 * signal in the middle of being processed after
660 * being removed from the queue. Clear that too.
662 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
666 return !sig_ignored(p, sig);
670 * Test if P wants to take SIG. After we've checked all threads with this,
671 * it's equivalent to finding no threads not blocking SIG. Any threads not
672 * blocking SIG were ruled out because they are not running and already
673 * have pending signals. Such threads will dequeue from the shared queue
674 * as soon as they're available, so putting the signal on the shared queue
675 * will be equivalent to sending it to one such thread.
677 static inline int wants_signal(int sig, struct task_struct *p)
679 if (sigismember(&p->blocked, sig))
681 if (p->flags & PF_EXITING)
685 if (task_is_stopped_or_traced(p))
687 return task_curr(p) || !signal_pending(p);
690 static void complete_signal(int sig, struct task_struct *p, int group)
692 struct signal_struct *signal = p->signal;
693 struct task_struct *t;
696 * Now find a thread we can wake up to take the signal off the queue.
698 * If the main thread wants the signal, it gets first crack.
699 * Probably the least surprising to the average bear.
701 if (wants_signal(sig, p))
703 else if (!group || thread_group_empty(p))
705 * There is just one thread and it does not need to be woken.
706 * It will dequeue unblocked signals before it runs again.
711 * Otherwise try to find a suitable thread.
713 t = signal->curr_target;
714 while (!wants_signal(sig, t)) {
716 if (t == signal->curr_target)
718 * No thread needs to be woken.
719 * Any eligible threads will see
720 * the signal in the queue soon.
724 signal->curr_target = t;
728 * Found a killable thread. If the signal will be fatal,
729 * then start taking the whole group down immediately.
731 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
732 !sigismember(&t->real_blocked, sig) &&
733 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
735 * This signal will be fatal to the whole group.
737 if (!sig_kernel_coredump(sig)) {
739 * Start a group exit and wake everybody up.
740 * This way we don't have other threads
741 * running and doing things after a slower
742 * thread has the fatal signal pending.
744 signal->flags = SIGNAL_GROUP_EXIT;
745 signal->group_exit_code = sig;
746 signal->group_stop_count = 0;
749 sigaddset(&t->pending.signal, SIGKILL);
750 signal_wake_up(t, 1);
751 } while_each_thread(p, t);
757 * The signal is already in the shared-pending queue.
758 * Tell the chosen thread to wake up and dequeue it.
760 signal_wake_up(t, sig == SIGKILL);
764 static inline int legacy_queue(struct sigpending *signals, int sig)
766 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
769 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
772 struct sigpending *pending;
775 assert_spin_locked(&t->sighand->siglock);
776 if (!prepare_signal(sig, t))
779 pending = group ? &t->signal->shared_pending : &t->pending;
781 * Short-circuit ignored signals and support queuing
782 * exactly one non-rt signal, so that we can get more
783 * detailed information about the cause of the signal.
785 if (legacy_queue(pending, sig))
788 * fast-pathed signals for kernel-internal things like SIGSTOP
791 if (info == SEND_SIG_FORCED)
794 /* Real-time signals must be queued if sent by sigqueue, or
795 some other real-time mechanism. It is implementation
796 defined whether kill() does so. We attempt to do so, on
797 the principle of least surprise, but since kill is not
798 allowed to fail with EAGAIN when low on memory we just
799 make sure at least one signal gets delivered and don't
800 pass on the info struct. */
802 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
803 (is_si_special(info) ||
804 info->si_code >= 0)));
806 list_add_tail(&q->list, &pending->list);
807 switch ((unsigned long) info) {
808 case (unsigned long) SEND_SIG_NOINFO:
809 q->info.si_signo = sig;
810 q->info.si_errno = 0;
811 q->info.si_code = SI_USER;
812 q->info.si_pid = task_pid_vnr(current);
813 q->info.si_uid = current->uid;
815 case (unsigned long) SEND_SIG_PRIV:
816 q->info.si_signo = sig;
817 q->info.si_errno = 0;
818 q->info.si_code = SI_KERNEL;
823 copy_siginfo(&q->info, info);
826 } else if (!is_si_special(info)) {
827 if (sig >= SIGRTMIN && info->si_code != SI_USER)
829 * Queue overflow, abort. We may abort if the signal was rt
830 * and sent by user using something other than kill().
836 signalfd_notify(t, sig);
837 sigaddset(&pending->signal, sig);
838 complete_signal(sig, t, group);
842 int print_fatal_signals;
844 static void print_fatal_signal(struct pt_regs *regs, int signr)
846 printk("%s/%d: potentially unexpected fatal signal %d.\n",
847 current->comm, task_pid_nr(current), signr);
849 #if defined(__i386__) && !defined(__arch_um__)
850 printk("code at %08lx: ", regs->ip);
853 for (i = 0; i < 16; i++) {
856 __get_user(insn, (unsigned char *)(regs->ip + i));
857 printk("%02x ", insn);
865 static int __init setup_print_fatal_signals(char *str)
867 get_option (&str, &print_fatal_signals);
872 __setup("print-fatal-signals=", setup_print_fatal_signals);
875 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
877 return send_signal(sig, info, p, 1);
881 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
883 return send_signal(sig, info, t, 0);
887 * Force a signal that the process can't ignore: if necessary
888 * we unblock the signal and change any SIG_IGN to SIG_DFL.
890 * Note: If we unblock the signal, we always reset it to SIG_DFL,
891 * since we do not want to have a signal handler that was blocked
892 * be invoked when user space had explicitly blocked it.
894 * We don't want to have recursive SIGSEGV's etc, for example.
897 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
899 unsigned long int flags;
900 int ret, blocked, ignored;
901 struct k_sigaction *action;
903 spin_lock_irqsave(&t->sighand->siglock, flags);
904 action = &t->sighand->action[sig-1];
905 ignored = action->sa.sa_handler == SIG_IGN;
906 blocked = sigismember(&t->blocked, sig);
907 if (blocked || ignored) {
908 action->sa.sa_handler = SIG_DFL;
910 sigdelset(&t->blocked, sig);
911 recalc_sigpending_and_wake(t);
914 ret = specific_send_sig_info(sig, info, t);
915 spin_unlock_irqrestore(&t->sighand->siglock, flags);
921 force_sig_specific(int sig, struct task_struct *t)
923 force_sig_info(sig, SEND_SIG_FORCED, t);
927 * Nuke all other threads in the group.
929 void zap_other_threads(struct task_struct *p)
931 struct task_struct *t;
933 p->signal->group_stop_count = 0;
935 for (t = next_thread(p); t != p; t = next_thread(t)) {
937 * Don't bother with already dead threads
942 /* SIGKILL will be handled before any pending SIGSTOP */
943 sigaddset(&t->pending.signal, SIGKILL);
944 signal_wake_up(t, 1);
948 int __fatal_signal_pending(struct task_struct *tsk)
950 return sigismember(&tsk->pending.signal, SIGKILL);
952 EXPORT_SYMBOL(__fatal_signal_pending);
954 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
956 struct sighand_struct *sighand;
960 sighand = rcu_dereference(tsk->sighand);
961 if (unlikely(sighand == NULL))
964 spin_lock_irqsave(&sighand->siglock, *flags);
965 if (likely(sighand == tsk->sighand))
967 spin_unlock_irqrestore(&sighand->siglock, *flags);
974 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
979 ret = check_kill_permission(sig, info, p);
983 if (lock_task_sighand(p, &flags)) {
984 ret = __group_send_sig_info(sig, info, p);
985 unlock_task_sighand(p, &flags);
993 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
994 * control characters do (^C, ^Z etc)
997 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
999 struct task_struct *p = NULL;
1000 int retval, success;
1004 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1005 int err = group_send_sig_info(sig, info, p);
1008 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1009 return success ? 0 : retval;
1012 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1015 struct task_struct *p;
1019 p = pid_task(pid, PIDTYPE_PID);
1021 error = group_send_sig_info(sig, info, p);
1022 if (unlikely(error == -ESRCH))
1024 * The task was unhashed in between, try again.
1025 * If it is dead, pid_task() will return NULL,
1026 * if we race with de_thread() it will find the
1037 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1041 error = kill_pid_info(sig, info, find_vpid(pid));
1046 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1047 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1048 uid_t uid, uid_t euid, u32 secid)
1051 struct task_struct *p;
1053 if (!valid_signal(sig))
1056 read_lock(&tasklist_lock);
1057 p = pid_task(pid, PIDTYPE_PID);
1062 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1063 && (euid != p->suid) && (euid != p->uid)
1064 && (uid != p->suid) && (uid != p->uid)) {
1068 ret = security_task_kill(p, info, sig, secid);
1071 if (sig && p->sighand) {
1072 unsigned long flags;
1073 spin_lock_irqsave(&p->sighand->siglock, flags);
1074 ret = __group_send_sig_info(sig, info, p);
1075 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1078 read_unlock(&tasklist_lock);
1081 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1084 * kill_something_info() interprets pid in interesting ways just like kill(2).
1086 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1087 * is probably wrong. Should make it like BSD or SYSV.
1090 static int kill_something_info(int sig, struct siginfo *info, int pid)
1096 ret = kill_pid_info(sig, info, find_vpid(pid));
1101 read_lock(&tasklist_lock);
1103 ret = __kill_pgrp_info(sig, info,
1104 pid ? find_vpid(-pid) : task_pgrp(current));
1106 int retval = 0, count = 0;
1107 struct task_struct * p;
1109 for_each_process(p) {
1110 if (p->pid > 1 && !same_thread_group(p, current)) {
1111 int err = group_send_sig_info(sig, info, p);
1117 ret = count ? retval : -ESRCH;
1119 read_unlock(&tasklist_lock);
1125 * These are for backward compatibility with the rest of the kernel source.
1129 * The caller must ensure the task can't exit.
1132 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1135 unsigned long flags;
1138 * Make sure legacy kernel users don't send in bad values
1139 * (normal paths check this in check_kill_permission).
1141 if (!valid_signal(sig))
1144 spin_lock_irqsave(&p->sighand->siglock, flags);
1145 ret = specific_send_sig_info(sig, info, p);
1146 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1150 #define __si_special(priv) \
1151 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1154 send_sig(int sig, struct task_struct *p, int priv)
1156 return send_sig_info(sig, __si_special(priv), p);
1160 force_sig(int sig, struct task_struct *p)
1162 force_sig_info(sig, SEND_SIG_PRIV, p);
1166 * When things go south during signal handling, we
1167 * will force a SIGSEGV. And if the signal that caused
1168 * the problem was already a SIGSEGV, we'll want to
1169 * make sure we don't even try to deliver the signal..
1172 force_sigsegv(int sig, struct task_struct *p)
1174 if (sig == SIGSEGV) {
1175 unsigned long flags;
1176 spin_lock_irqsave(&p->sighand->siglock, flags);
1177 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1178 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1180 force_sig(SIGSEGV, p);
1184 int kill_pgrp(struct pid *pid, int sig, int priv)
1188 read_lock(&tasklist_lock);
1189 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1190 read_unlock(&tasklist_lock);
1194 EXPORT_SYMBOL(kill_pgrp);
1196 int kill_pid(struct pid *pid, int sig, int priv)
1198 return kill_pid_info(sig, __si_special(priv), pid);
1200 EXPORT_SYMBOL(kill_pid);
1203 kill_proc(pid_t pid, int sig, int priv)
1208 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1214 * These functions support sending signals using preallocated sigqueue
1215 * structures. This is needed "because realtime applications cannot
1216 * afford to lose notifications of asynchronous events, like timer
1217 * expirations or I/O completions". In the case of Posix Timers
1218 * we allocate the sigqueue structure from the timer_create. If this
1219 * allocation fails we are able to report the failure to the application
1220 * with an EAGAIN error.
1223 struct sigqueue *sigqueue_alloc(void)
1227 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1228 q->flags |= SIGQUEUE_PREALLOC;
1232 void sigqueue_free(struct sigqueue *q)
1234 unsigned long flags;
1235 spinlock_t *lock = ¤t->sighand->siglock;
1237 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1239 * If the signal is still pending remove it from the
1240 * pending queue. We must hold ->siglock while testing
1241 * q->list to serialize with collect_signal().
1243 spin_lock_irqsave(lock, flags);
1244 if (!list_empty(&q->list))
1245 list_del_init(&q->list);
1246 spin_unlock_irqrestore(lock, flags);
1248 q->flags &= ~SIGQUEUE_PREALLOC;
1252 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1254 int sig = q->info.si_signo;
1255 struct sigpending *pending;
1256 unsigned long flags;
1259 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1262 if (!likely(lock_task_sighand(t, &flags)))
1265 ret = 1; /* the signal is ignored */
1266 if (!prepare_signal(sig, t))
1270 if (unlikely(!list_empty(&q->list))) {
1272 * If an SI_TIMER entry is already queue just increment
1273 * the overrun count.
1275 BUG_ON(q->info.si_code != SI_TIMER);
1276 q->info.si_overrun++;
1280 signalfd_notify(t, sig);
1281 pending = group ? &t->signal->shared_pending : &t->pending;
1282 list_add_tail(&q->list, &pending->list);
1283 sigaddset(&pending->signal, sig);
1284 complete_signal(sig, t, group);
1286 unlock_task_sighand(t, &flags);
1292 * Wake up any threads in the parent blocked in wait* syscalls.
1294 static inline void __wake_up_parent(struct task_struct *p,
1295 struct task_struct *parent)
1297 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1301 * Let a parent know about the death of a child.
1302 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1305 void do_notify_parent(struct task_struct *tsk, int sig)
1307 struct siginfo info;
1308 unsigned long flags;
1309 struct sighand_struct *psig;
1313 /* do_notify_parent_cldstop should have been called instead. */
1314 BUG_ON(task_is_stopped_or_traced(tsk));
1316 BUG_ON(!tsk->ptrace &&
1317 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1319 info.si_signo = sig;
1322 * we are under tasklist_lock here so our parent is tied to
1323 * us and cannot exit and release its namespace.
1325 * the only it can is to switch its nsproxy with sys_unshare,
1326 * bu uncharing pid namespaces is not allowed, so we'll always
1327 * see relevant namespace
1329 * write_lock() currently calls preempt_disable() which is the
1330 * same as rcu_read_lock(), but according to Oleg, this is not
1331 * correct to rely on this
1334 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1337 info.si_uid = tsk->uid;
1339 /* FIXME: find out whether or not this is supposed to be c*time. */
1340 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1341 tsk->signal->utime));
1342 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1343 tsk->signal->stime));
1345 info.si_status = tsk->exit_code & 0x7f;
1346 if (tsk->exit_code & 0x80)
1347 info.si_code = CLD_DUMPED;
1348 else if (tsk->exit_code & 0x7f)
1349 info.si_code = CLD_KILLED;
1351 info.si_code = CLD_EXITED;
1352 info.si_status = tsk->exit_code >> 8;
1355 psig = tsk->parent->sighand;
1356 spin_lock_irqsave(&psig->siglock, flags);
1357 if (!tsk->ptrace && sig == SIGCHLD &&
1358 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1359 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1361 * We are exiting and our parent doesn't care. POSIX.1
1362 * defines special semantics for setting SIGCHLD to SIG_IGN
1363 * or setting the SA_NOCLDWAIT flag: we should be reaped
1364 * automatically and not left for our parent's wait4 call.
1365 * Rather than having the parent do it as a magic kind of
1366 * signal handler, we just set this to tell do_exit that we
1367 * can be cleaned up without becoming a zombie. Note that
1368 * we still call __wake_up_parent in this case, because a
1369 * blocked sys_wait4 might now return -ECHILD.
1371 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1372 * is implementation-defined: we do (if you don't want
1373 * it, just use SIG_IGN instead).
1375 tsk->exit_signal = -1;
1376 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1379 if (valid_signal(sig) && sig > 0)
1380 __group_send_sig_info(sig, &info, tsk->parent);
1381 __wake_up_parent(tsk, tsk->parent);
1382 spin_unlock_irqrestore(&psig->siglock, flags);
1385 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1387 struct siginfo info;
1388 unsigned long flags;
1389 struct task_struct *parent;
1390 struct sighand_struct *sighand;
1392 if (tsk->ptrace & PT_PTRACED)
1393 parent = tsk->parent;
1395 tsk = tsk->group_leader;
1396 parent = tsk->real_parent;
1399 info.si_signo = SIGCHLD;
1402 * see comment in do_notify_parent() abot the following 3 lines
1405 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1408 info.si_uid = tsk->uid;
1410 /* FIXME: find out whether or not this is supposed to be c*time. */
1411 info.si_utime = cputime_to_jiffies(tsk->utime);
1412 info.si_stime = cputime_to_jiffies(tsk->stime);
1417 info.si_status = SIGCONT;
1420 info.si_status = tsk->signal->group_exit_code & 0x7f;
1423 info.si_status = tsk->exit_code & 0x7f;
1429 sighand = parent->sighand;
1430 spin_lock_irqsave(&sighand->siglock, flags);
1431 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1432 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1433 __group_send_sig_info(SIGCHLD, &info, parent);
1435 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1437 __wake_up_parent(tsk, parent);
1438 spin_unlock_irqrestore(&sighand->siglock, flags);
1441 static inline int may_ptrace_stop(void)
1443 if (!likely(current->ptrace & PT_PTRACED))
1446 * Are we in the middle of do_coredump?
1447 * If so and our tracer is also part of the coredump stopping
1448 * is a deadlock situation, and pointless because our tracer
1449 * is dead so don't allow us to stop.
1450 * If SIGKILL was already sent before the caller unlocked
1451 * ->siglock we must see ->core_waiters != 0. Otherwise it
1452 * is safe to enter schedule().
1454 if (unlikely(current->mm->core_waiters) &&
1455 unlikely(current->mm == current->parent->mm))
1462 * Return nonzero if there is a SIGKILL that should be waking us up.
1463 * Called with the siglock held.
1465 static int sigkill_pending(struct task_struct *tsk)
1467 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1468 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1469 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1473 * This must be called with current->sighand->siglock held.
1475 * This should be the path for all ptrace stops.
1476 * We always set current->last_siginfo while stopped here.
1477 * That makes it a way to test a stopped process for
1478 * being ptrace-stopped vs being job-control-stopped.
1480 * If we actually decide not to stop at all because the tracer
1481 * is gone, we keep current->exit_code unless clear_code.
1483 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1487 if (arch_ptrace_stop_needed(exit_code, info)) {
1489 * The arch code has something special to do before a
1490 * ptrace stop. This is allowed to block, e.g. for faults
1491 * on user stack pages. We can't keep the siglock while
1492 * calling arch_ptrace_stop, so we must release it now.
1493 * To preserve proper semantics, we must do this before
1494 * any signal bookkeeping like checking group_stop_count.
1495 * Meanwhile, a SIGKILL could come in before we retake the
1496 * siglock. That must prevent us from sleeping in TASK_TRACED.
1497 * So after regaining the lock, we must check for SIGKILL.
1499 spin_unlock_irq(¤t->sighand->siglock);
1500 arch_ptrace_stop(exit_code, info);
1501 spin_lock_irq(¤t->sighand->siglock);
1502 killed = sigkill_pending(current);
1506 * If there is a group stop in progress,
1507 * we must participate in the bookkeeping.
1509 if (current->signal->group_stop_count > 0)
1510 --current->signal->group_stop_count;
1512 current->last_siginfo = info;
1513 current->exit_code = exit_code;
1515 /* Let the debugger run. */
1516 __set_current_state(TASK_TRACED);
1517 spin_unlock_irq(¤t->sighand->siglock);
1518 read_lock(&tasklist_lock);
1519 if (!unlikely(killed) && may_ptrace_stop()) {
1520 do_notify_parent_cldstop(current, CLD_TRAPPED);
1521 read_unlock(&tasklist_lock);
1525 * By the time we got the lock, our tracer went away.
1526 * Don't drop the lock yet, another tracer may come.
1528 __set_current_state(TASK_RUNNING);
1530 current->exit_code = 0;
1531 read_unlock(&tasklist_lock);
1535 * While in TASK_TRACED, we were considered "frozen enough".
1536 * Now that we woke up, it's crucial if we're supposed to be
1537 * frozen that we freeze now before running anything substantial.
1542 * We are back. Now reacquire the siglock before touching
1543 * last_siginfo, so that we are sure to have synchronized with
1544 * any signal-sending on another CPU that wants to examine it.
1546 spin_lock_irq(¤t->sighand->siglock);
1547 current->last_siginfo = NULL;
1550 * Queued signals ignored us while we were stopped for tracing.
1551 * So check for any that we should take before resuming user mode.
1552 * This sets TIF_SIGPENDING, but never clears it.
1554 recalc_sigpending_tsk(current);
1557 void ptrace_notify(int exit_code)
1561 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1563 memset(&info, 0, sizeof info);
1564 info.si_signo = SIGTRAP;
1565 info.si_code = exit_code;
1566 info.si_pid = task_pid_vnr(current);
1567 info.si_uid = current->uid;
1569 /* Let the debugger run. */
1570 spin_lock_irq(¤t->sighand->siglock);
1571 ptrace_stop(exit_code, 1, &info);
1572 spin_unlock_irq(¤t->sighand->siglock);
1576 finish_stop(int stop_count)
1579 * If there are no other threads in the group, or if there is
1580 * a group stop in progress and we are the last to stop,
1581 * report to the parent. When ptraced, every thread reports itself.
1583 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1584 read_lock(&tasklist_lock);
1585 do_notify_parent_cldstop(current, CLD_STOPPED);
1586 read_unlock(&tasklist_lock);
1591 } while (try_to_freeze());
1593 * Now we don't run again until continued.
1595 current->exit_code = 0;
1599 * This performs the stopping for SIGSTOP and other stop signals.
1600 * We have to stop all threads in the thread group.
1601 * Returns nonzero if we've actually stopped and released the siglock.
1602 * Returns zero if we didn't stop and still hold the siglock.
1604 static int do_signal_stop(int signr)
1606 struct signal_struct *sig = current->signal;
1609 if (sig->group_stop_count > 0) {
1611 * There is a group stop in progress. We don't need to
1612 * start another one.
1614 stop_count = --sig->group_stop_count;
1616 struct task_struct *t;
1618 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1619 unlikely(signal_group_exit(sig)))
1622 * There is no group stop already in progress.
1623 * We must initiate one now.
1625 sig->group_exit_code = signr;
1628 for (t = next_thread(current); t != current; t = next_thread(t))
1630 * Setting state to TASK_STOPPED for a group
1631 * stop is always done with the siglock held,
1632 * so this check has no races.
1634 if (!(t->flags & PF_EXITING) &&
1635 !task_is_stopped_or_traced(t)) {
1637 signal_wake_up(t, 0);
1639 sig->group_stop_count = stop_count;
1642 if (stop_count == 0)
1643 sig->flags = SIGNAL_STOP_STOPPED;
1644 current->exit_code = sig->group_exit_code;
1645 __set_current_state(TASK_STOPPED);
1647 spin_unlock_irq(¤t->sighand->siglock);
1648 finish_stop(stop_count);
1652 static int ptrace_signal(int signr, siginfo_t *info,
1653 struct pt_regs *regs, void *cookie)
1655 if (!(current->ptrace & PT_PTRACED))
1658 ptrace_signal_deliver(regs, cookie);
1660 /* Let the debugger run. */
1661 ptrace_stop(signr, 0, info);
1663 /* We're back. Did the debugger cancel the sig? */
1664 signr = current->exit_code;
1668 current->exit_code = 0;
1670 /* Update the siginfo structure if the signal has
1671 changed. If the debugger wanted something
1672 specific in the siginfo structure then it should
1673 have updated *info via PTRACE_SETSIGINFO. */
1674 if (signr != info->si_signo) {
1675 info->si_signo = signr;
1677 info->si_code = SI_USER;
1678 info->si_pid = task_pid_vnr(current->parent);
1679 info->si_uid = current->parent->uid;
1682 /* If the (new) signal is now blocked, requeue it. */
1683 if (sigismember(¤t->blocked, signr)) {
1684 specific_send_sig_info(signr, info, current);
1691 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1692 struct pt_regs *regs, void *cookie)
1694 struct sighand_struct *sighand = current->sighand;
1695 struct signal_struct *signal = current->signal;
1700 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1701 * While in TASK_STOPPED, we were considered "frozen enough".
1702 * Now that we woke up, it's crucial if we're supposed to be
1703 * frozen that we freeze now before running anything substantial.
1707 spin_lock_irq(&sighand->siglock);
1709 * Every stopped thread goes here after wakeup. Check to see if
1710 * we should notify the parent, prepare_signal(SIGCONT) encodes
1711 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1713 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1714 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1715 ? CLD_CONTINUED : CLD_STOPPED;
1716 signal->flags &= ~SIGNAL_CLD_MASK;
1717 spin_unlock_irq(&sighand->siglock);
1719 read_lock(&tasklist_lock);
1720 do_notify_parent_cldstop(current->group_leader, why);
1721 read_unlock(&tasklist_lock);
1726 struct k_sigaction *ka;
1728 if (unlikely(signal->group_stop_count > 0) &&
1732 signr = dequeue_signal(current, ¤t->blocked, info);
1734 break; /* will return 0 */
1736 if (signr != SIGKILL) {
1737 signr = ptrace_signal(signr, info, regs, cookie);
1742 ka = &sighand->action[signr-1];
1743 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1745 if (ka->sa.sa_handler != SIG_DFL) {
1746 /* Run the handler. */
1749 if (ka->sa.sa_flags & SA_ONESHOT)
1750 ka->sa.sa_handler = SIG_DFL;
1752 break; /* will return non-zero "signr" value */
1756 * Now we are doing the default action for this signal.
1758 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1762 * Global init gets no signals it doesn't want.
1764 if (is_global_init(current))
1767 if (sig_kernel_stop(signr)) {
1769 * The default action is to stop all threads in
1770 * the thread group. The job control signals
1771 * do nothing in an orphaned pgrp, but SIGSTOP
1772 * always works. Note that siglock needs to be
1773 * dropped during the call to is_orphaned_pgrp()
1774 * because of lock ordering with tasklist_lock.
1775 * This allows an intervening SIGCONT to be posted.
1776 * We need to check for that and bail out if necessary.
1778 if (signr != SIGSTOP) {
1779 spin_unlock_irq(&sighand->siglock);
1781 /* signals can be posted during this window */
1783 if (is_current_pgrp_orphaned())
1786 spin_lock_irq(&sighand->siglock);
1789 if (likely(do_signal_stop(signr))) {
1790 /* It released the siglock. */
1795 * We didn't actually stop, due to a race
1796 * with SIGCONT or something like that.
1801 spin_unlock_irq(&sighand->siglock);
1804 * Anything else is fatal, maybe with a core dump.
1806 current->flags |= PF_SIGNALED;
1808 if (sig_kernel_coredump(signr)) {
1809 if (print_fatal_signals)
1810 print_fatal_signal(regs, signr);
1812 * If it was able to dump core, this kills all
1813 * other threads in the group and synchronizes with
1814 * their demise. If we lost the race with another
1815 * thread getting here, it set group_exit_code
1816 * first and our do_group_exit call below will use
1817 * that value and ignore the one we pass it.
1819 do_coredump((long)signr, signr, regs);
1823 * Death signals, no core dump.
1825 do_group_exit(signr);
1828 spin_unlock_irq(&sighand->siglock);
1832 void exit_signals(struct task_struct *tsk)
1835 struct task_struct *t;
1837 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1838 tsk->flags |= PF_EXITING;
1842 spin_lock_irq(&tsk->sighand->siglock);
1844 * From now this task is not visible for group-wide signals,
1845 * see wants_signal(), do_signal_stop().
1847 tsk->flags |= PF_EXITING;
1848 if (!signal_pending(tsk))
1851 /* It could be that __group_complete_signal() choose us to
1852 * notify about group-wide signal. Another thread should be
1853 * woken now to take the signal since we will not.
1855 for (t = tsk; (t = next_thread(t)) != tsk; )
1856 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1857 recalc_sigpending_and_wake(t);
1859 if (unlikely(tsk->signal->group_stop_count) &&
1860 !--tsk->signal->group_stop_count) {
1861 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1865 spin_unlock_irq(&tsk->sighand->siglock);
1867 if (unlikely(group_stop)) {
1868 read_lock(&tasklist_lock);
1869 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1870 read_unlock(&tasklist_lock);
1874 EXPORT_SYMBOL(recalc_sigpending);
1875 EXPORT_SYMBOL_GPL(dequeue_signal);
1876 EXPORT_SYMBOL(flush_signals);
1877 EXPORT_SYMBOL(force_sig);
1878 EXPORT_SYMBOL(kill_proc);
1879 EXPORT_SYMBOL(ptrace_notify);
1880 EXPORT_SYMBOL(send_sig);
1881 EXPORT_SYMBOL(send_sig_info);
1882 EXPORT_SYMBOL(sigprocmask);
1883 EXPORT_SYMBOL(block_all_signals);
1884 EXPORT_SYMBOL(unblock_all_signals);
1888 * System call entry points.
1891 asmlinkage long sys_restart_syscall(void)
1893 struct restart_block *restart = ¤t_thread_info()->restart_block;
1894 return restart->fn(restart);
1897 long do_no_restart_syscall(struct restart_block *param)
1903 * We don't need to get the kernel lock - this is all local to this
1904 * particular thread.. (and that's good, because this is _heavily_
1905 * used by various programs)
1909 * This is also useful for kernel threads that want to temporarily
1910 * (or permanently) block certain signals.
1912 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1913 * interface happily blocks "unblockable" signals like SIGKILL
1916 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1920 spin_lock_irq(¤t->sighand->siglock);
1922 *oldset = current->blocked;
1927 sigorsets(¤t->blocked, ¤t->blocked, set);
1930 signandsets(¤t->blocked, ¤t->blocked, set);
1933 current->blocked = *set;
1938 recalc_sigpending();
1939 spin_unlock_irq(¤t->sighand->siglock);
1945 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1947 int error = -EINVAL;
1948 sigset_t old_set, new_set;
1950 /* XXX: Don't preclude handling different sized sigset_t's. */
1951 if (sigsetsize != sizeof(sigset_t))
1956 if (copy_from_user(&new_set, set, sizeof(*set)))
1958 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1960 error = sigprocmask(how, &new_set, &old_set);
1966 spin_lock_irq(¤t->sighand->siglock);
1967 old_set = current->blocked;
1968 spin_unlock_irq(¤t->sighand->siglock);
1972 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1980 long do_sigpending(void __user *set, unsigned long sigsetsize)
1982 long error = -EINVAL;
1985 if (sigsetsize > sizeof(sigset_t))
1988 spin_lock_irq(¤t->sighand->siglock);
1989 sigorsets(&pending, ¤t->pending.signal,
1990 ¤t->signal->shared_pending.signal);
1991 spin_unlock_irq(¤t->sighand->siglock);
1993 /* Outside the lock because only this thread touches it. */
1994 sigandsets(&pending, ¤t->blocked, &pending);
1997 if (!copy_to_user(set, &pending, sigsetsize))
2005 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2007 return do_sigpending(set, sigsetsize);
2010 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2012 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2016 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2018 if (from->si_code < 0)
2019 return __copy_to_user(to, from, sizeof(siginfo_t))
2022 * If you change siginfo_t structure, please be sure
2023 * this code is fixed accordingly.
2024 * Please remember to update the signalfd_copyinfo() function
2025 * inside fs/signalfd.c too, in case siginfo_t changes.
2026 * It should never copy any pad contained in the structure
2027 * to avoid security leaks, but must copy the generic
2028 * 3 ints plus the relevant union member.
2030 err = __put_user(from->si_signo, &to->si_signo);
2031 err |= __put_user(from->si_errno, &to->si_errno);
2032 err |= __put_user((short)from->si_code, &to->si_code);
2033 switch (from->si_code & __SI_MASK) {
2035 err |= __put_user(from->si_pid, &to->si_pid);
2036 err |= __put_user(from->si_uid, &to->si_uid);
2039 err |= __put_user(from->si_tid, &to->si_tid);
2040 err |= __put_user(from->si_overrun, &to->si_overrun);
2041 err |= __put_user(from->si_ptr, &to->si_ptr);
2044 err |= __put_user(from->si_band, &to->si_band);
2045 err |= __put_user(from->si_fd, &to->si_fd);
2048 err |= __put_user(from->si_addr, &to->si_addr);
2049 #ifdef __ARCH_SI_TRAPNO
2050 err |= __put_user(from->si_trapno, &to->si_trapno);
2054 err |= __put_user(from->si_pid, &to->si_pid);
2055 err |= __put_user(from->si_uid, &to->si_uid);
2056 err |= __put_user(from->si_status, &to->si_status);
2057 err |= __put_user(from->si_utime, &to->si_utime);
2058 err |= __put_user(from->si_stime, &to->si_stime);
2060 case __SI_RT: /* This is not generated by the kernel as of now. */
2061 case __SI_MESGQ: /* But this is */
2062 err |= __put_user(from->si_pid, &to->si_pid);
2063 err |= __put_user(from->si_uid, &to->si_uid);
2064 err |= __put_user(from->si_ptr, &to->si_ptr);
2066 default: /* this is just in case for now ... */
2067 err |= __put_user(from->si_pid, &to->si_pid);
2068 err |= __put_user(from->si_uid, &to->si_uid);
2077 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2078 siginfo_t __user *uinfo,
2079 const struct timespec __user *uts,
2088 /* XXX: Don't preclude handling different sized sigset_t's. */
2089 if (sigsetsize != sizeof(sigset_t))
2092 if (copy_from_user(&these, uthese, sizeof(these)))
2096 * Invert the set of allowed signals to get those we
2099 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2103 if (copy_from_user(&ts, uts, sizeof(ts)))
2105 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2110 spin_lock_irq(¤t->sighand->siglock);
2111 sig = dequeue_signal(current, &these, &info);
2113 timeout = MAX_SCHEDULE_TIMEOUT;
2115 timeout = (timespec_to_jiffies(&ts)
2116 + (ts.tv_sec || ts.tv_nsec));
2119 /* None ready -- temporarily unblock those we're
2120 * interested while we are sleeping in so that we'll
2121 * be awakened when they arrive. */
2122 current->real_blocked = current->blocked;
2123 sigandsets(¤t->blocked, ¤t->blocked, &these);
2124 recalc_sigpending();
2125 spin_unlock_irq(¤t->sighand->siglock);
2127 timeout = schedule_timeout_interruptible(timeout);
2129 spin_lock_irq(¤t->sighand->siglock);
2130 sig = dequeue_signal(current, &these, &info);
2131 current->blocked = current->real_blocked;
2132 siginitset(¤t->real_blocked, 0);
2133 recalc_sigpending();
2136 spin_unlock_irq(¤t->sighand->siglock);
2141 if (copy_siginfo_to_user(uinfo, &info))
2154 sys_kill(int pid, int sig)
2156 struct siginfo info;
2158 info.si_signo = sig;
2160 info.si_code = SI_USER;
2161 info.si_pid = task_tgid_vnr(current);
2162 info.si_uid = current->uid;
2164 return kill_something_info(sig, &info, pid);
2167 static int do_tkill(int tgid, int pid, int sig)
2170 struct siginfo info;
2171 struct task_struct *p;
2172 unsigned long flags;
2175 info.si_signo = sig;
2177 info.si_code = SI_TKILL;
2178 info.si_pid = task_tgid_vnr(current);
2179 info.si_uid = current->uid;
2182 p = find_task_by_vpid(pid);
2183 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2184 error = check_kill_permission(sig, &info, p);
2186 * The null signal is a permissions and process existence
2187 * probe. No signal is actually delivered.
2189 * If lock_task_sighand() fails we pretend the task dies
2190 * after receiving the signal. The window is tiny, and the
2191 * signal is private anyway.
2193 if (!error && sig && lock_task_sighand(p, &flags)) {
2194 error = specific_send_sig_info(sig, &info, p);
2195 unlock_task_sighand(p, &flags);
2204 * sys_tgkill - send signal to one specific thread
2205 * @tgid: the thread group ID of the thread
2206 * @pid: the PID of the thread
2207 * @sig: signal to be sent
2209 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2210 * exists but it's not belonging to the target process anymore. This
2211 * method solves the problem of threads exiting and PIDs getting reused.
2213 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2215 /* This is only valid for single tasks */
2216 if (pid <= 0 || tgid <= 0)
2219 return do_tkill(tgid, pid, sig);
2223 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2226 sys_tkill(int pid, int sig)
2228 /* This is only valid for single tasks */
2232 return do_tkill(0, pid, sig);
2236 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2240 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2243 /* Not even root can pretend to send signals from the kernel.
2244 Nor can they impersonate a kill(), which adds source info. */
2245 if (info.si_code >= 0)
2247 info.si_signo = sig;
2249 /* POSIX.1b doesn't mention process groups. */
2250 return kill_proc_info(sig, &info, pid);
2253 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2255 struct task_struct *t = current;
2256 struct k_sigaction *k;
2259 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2262 k = &t->sighand->action[sig-1];
2264 spin_lock_irq(¤t->sighand->siglock);
2269 sigdelsetmask(&act->sa.sa_mask,
2270 sigmask(SIGKILL) | sigmask(SIGSTOP));
2274 * "Setting a signal action to SIG_IGN for a signal that is
2275 * pending shall cause the pending signal to be discarded,
2276 * whether or not it is blocked."
2278 * "Setting a signal action to SIG_DFL for a signal that is
2279 * pending and whose default action is to ignore the signal
2280 * (for example, SIGCHLD), shall cause the pending signal to
2281 * be discarded, whether or not it is blocked"
2283 if (__sig_ignored(t, sig)) {
2285 sigaddset(&mask, sig);
2286 rm_from_queue_full(&mask, &t->signal->shared_pending);
2288 rm_from_queue_full(&mask, &t->pending);
2290 } while (t != current);
2294 spin_unlock_irq(¤t->sighand->siglock);
2299 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2305 oss.ss_sp = (void __user *) current->sas_ss_sp;
2306 oss.ss_size = current->sas_ss_size;
2307 oss.ss_flags = sas_ss_flags(sp);
2316 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2317 || __get_user(ss_sp, &uss->ss_sp)
2318 || __get_user(ss_flags, &uss->ss_flags)
2319 || __get_user(ss_size, &uss->ss_size))
2323 if (on_sig_stack(sp))
2329 * Note - this code used to test ss_flags incorrectly
2330 * old code may have been written using ss_flags==0
2331 * to mean ss_flags==SS_ONSTACK (as this was the only
2332 * way that worked) - this fix preserves that older
2335 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2338 if (ss_flags == SS_DISABLE) {
2343 if (ss_size < MINSIGSTKSZ)
2347 current->sas_ss_sp = (unsigned long) ss_sp;
2348 current->sas_ss_size = ss_size;
2353 if (copy_to_user(uoss, &oss, sizeof(oss)))
2362 #ifdef __ARCH_WANT_SYS_SIGPENDING
2365 sys_sigpending(old_sigset_t __user *set)
2367 return do_sigpending(set, sizeof(*set));
2372 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2373 /* Some platforms have their own version with special arguments others
2374 support only sys_rt_sigprocmask. */
2377 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2380 old_sigset_t old_set, new_set;
2384 if (copy_from_user(&new_set, set, sizeof(*set)))
2386 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2388 spin_lock_irq(¤t->sighand->siglock);
2389 old_set = current->blocked.sig[0];
2397 sigaddsetmask(¤t->blocked, new_set);
2400 sigdelsetmask(¤t->blocked, new_set);
2403 current->blocked.sig[0] = new_set;
2407 recalc_sigpending();
2408 spin_unlock_irq(¤t->sighand->siglock);
2414 old_set = current->blocked.sig[0];
2417 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2424 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2426 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2428 sys_rt_sigaction(int sig,
2429 const struct sigaction __user *act,
2430 struct sigaction __user *oact,
2433 struct k_sigaction new_sa, old_sa;
2436 /* XXX: Don't preclude handling different sized sigset_t's. */
2437 if (sigsetsize != sizeof(sigset_t))
2441 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2445 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2448 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2454 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2456 #ifdef __ARCH_WANT_SYS_SGETMASK
2459 * For backwards compatibility. Functionality superseded by sigprocmask.
2465 return current->blocked.sig[0];
2469 sys_ssetmask(int newmask)
2473 spin_lock_irq(¤t->sighand->siglock);
2474 old = current->blocked.sig[0];
2476 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2478 recalc_sigpending();
2479 spin_unlock_irq(¤t->sighand->siglock);
2483 #endif /* __ARCH_WANT_SGETMASK */
2485 #ifdef __ARCH_WANT_SYS_SIGNAL
2487 * For backwards compatibility. Functionality superseded by sigaction.
2489 asmlinkage unsigned long
2490 sys_signal(int sig, __sighandler_t handler)
2492 struct k_sigaction new_sa, old_sa;
2495 new_sa.sa.sa_handler = handler;
2496 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2497 sigemptyset(&new_sa.sa.sa_mask);
2499 ret = do_sigaction(sig, &new_sa, &old_sa);
2501 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2503 #endif /* __ARCH_WANT_SYS_SIGNAL */
2505 #ifdef __ARCH_WANT_SYS_PAUSE
2510 current->state = TASK_INTERRUPTIBLE;
2512 return -ERESTARTNOHAND;
2517 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2518 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2522 /* XXX: Don't preclude handling different sized sigset_t's. */
2523 if (sigsetsize != sizeof(sigset_t))
2526 if (copy_from_user(&newset, unewset, sizeof(newset)))
2528 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2530 spin_lock_irq(¤t->sighand->siglock);
2531 current->saved_sigmask = current->blocked;
2532 current->blocked = newset;
2533 recalc_sigpending();
2534 spin_unlock_irq(¤t->sighand->siglock);
2536 current->state = TASK_INTERRUPTIBLE;
2538 set_thread_flag(TIF_RESTORE_SIGMASK);
2539 return -ERESTARTNOHAND;
2541 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2543 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2548 void __init signals_init(void)
2550 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);