2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache *sigqueue_cachep;
42 static int __sig_ignored(struct task_struct *t, int sig)
46 /* Is it explicitly or implicitly ignored? */
48 handler = t->sighand->action[sig - 1].sa.sa_handler;
49 return handler == SIG_IGN ||
50 (handler == SIG_DFL && sig_kernel_ignore(sig));
53 static int sig_ignored(struct task_struct *t, int sig)
56 * Tracers always want to know about signals..
58 if (t->ptrace & PT_PTRACED)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
69 return __sig_ignored(t, sig);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
81 switch (_NSIG_WORDS) {
83 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
84 ready |= signal->sig[i] &~ blocked->sig[i];
87 case 4: ready = signal->sig[3] &~ blocked->sig[3];
88 ready |= signal->sig[2] &~ blocked->sig[2];
89 ready |= signal->sig[1] &~ blocked->sig[1];
90 ready |= signal->sig[0] &~ blocked->sig[0];
93 case 2: ready = signal->sig[1] &~ blocked->sig[1];
94 ready |= signal->sig[0] &~ blocked->sig[0];
97 case 1: ready = signal->sig[0] &~ blocked->sig[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct *t)
106 if (t->signal->group_stop_count > 0 ||
107 PENDING(&t->pending, &t->blocked) ||
108 PENDING(&t->signal->shared_pending, &t->blocked)) {
109 set_tsk_thread_flag(t, TIF_SIGPENDING);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct *t)
126 if (recalc_sigpending_tsk(t))
127 signal_wake_up(t, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current) && !freezing(current))
133 clear_thread_flag(TIF_SIGPENDING);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending *pending, sigset_t *mask)
141 unsigned long i, *s, *m, x;
144 s = pending->signal.sig;
146 switch (_NSIG_WORDS) {
148 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
149 if ((x = *s &~ *m) != 0) {
150 sig = ffz(~x) + i*_NSIG_BPW + 1;
155 case 2: if ((x = s[0] &~ m[0]) != 0)
157 else if ((x = s[1] &~ m[1]) != 0)
164 case 1: if ((x = *s &~ *m) != 0)
172 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
175 struct sigqueue *q = NULL;
176 struct user_struct *user;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user->sigpending);
185 if (override_rlimit ||
186 atomic_read(&user->sigpending) <=
187 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
188 q = kmem_cache_alloc(sigqueue_cachep, flags);
189 if (unlikely(q == NULL)) {
190 atomic_dec(&user->sigpending);
192 INIT_LIST_HEAD(&q->list);
194 q->user = get_uid(user);
199 static void __sigqueue_free(struct sigqueue *q)
201 if (q->flags & SIGQUEUE_PREALLOC)
203 atomic_dec(&q->user->sigpending);
205 kmem_cache_free(sigqueue_cachep, q);
208 void flush_sigqueue(struct sigpending *queue)
212 sigemptyset(&queue->signal);
213 while (!list_empty(&queue->list)) {
214 q = list_entry(queue->list.next, struct sigqueue , list);
215 list_del_init(&q->list);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct *t)
227 spin_lock_irqsave(&t->sighand->siglock, flags);
228 clear_tsk_thread_flag(t, TIF_SIGPENDING);
229 flush_sigqueue(&t->pending);
230 flush_sigqueue(&t->signal->shared_pending);
231 spin_unlock_irqrestore(&t->sighand->siglock, flags);
234 void ignore_signals(struct task_struct *t)
238 for (i = 0; i < _NSIG; ++i)
239 t->sighand->action[i].sa.sa_handler = SIG_IGN;
245 * Flush all handlers for a task.
249 flush_signal_handlers(struct task_struct *t, int force_default)
252 struct k_sigaction *ka = &t->sighand->action[0];
253 for (i = _NSIG ; i != 0 ; i--) {
254 if (force_default || ka->sa.sa_handler != SIG_IGN)
255 ka->sa.sa_handler = SIG_DFL;
257 sigemptyset(&ka->sa.sa_mask);
262 int unhandled_signal(struct task_struct *tsk, int sig)
264 if (is_global_init(tsk))
266 if (tsk->ptrace & PT_PTRACED)
268 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
269 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
273 /* Notify the system that a driver wants to block all signals for this
274 * process, and wants to be notified if any signals at all were to be
275 * sent/acted upon. If the notifier routine returns non-zero, then the
276 * signal will be acted upon after all. If the notifier routine returns 0,
277 * then then signal will be blocked. Only one block per process is
278 * allowed. priv is a pointer to private data that the notifier routine
279 * can use to determine if the signal should be blocked or not. */
282 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
286 spin_lock_irqsave(¤t->sighand->siglock, flags);
287 current->notifier_mask = mask;
288 current->notifier_data = priv;
289 current->notifier = notifier;
290 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
293 /* Notify the system that blocking has ended. */
296 unblock_all_signals(void)
300 spin_lock_irqsave(¤t->sighand->siglock, flags);
301 current->notifier = NULL;
302 current->notifier_data = NULL;
304 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
307 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
309 struct sigqueue *q, *first = NULL;
310 int still_pending = 0;
312 if (unlikely(!sigismember(&list->signal, sig)))
316 * Collect the siginfo appropriate to this signal. Check if
317 * there is another siginfo for the same signal.
319 list_for_each_entry(q, &list->list, list) {
320 if (q->info.si_signo == sig) {
329 list_del_init(&first->list);
330 copy_siginfo(info, &first->info);
331 __sigqueue_free(first);
333 sigdelset(&list->signal, sig);
336 /* Ok, it wasn't in the queue. This must be
337 a fast-pathed signal or we must have been
338 out of queue space. So zero out the info.
340 sigdelset(&list->signal, sig);
341 info->si_signo = sig;
350 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
353 int sig = next_signal(pending, mask);
356 if (current->notifier) {
357 if (sigismember(current->notifier_mask, sig)) {
358 if (!(current->notifier)(current->notifier_data)) {
359 clear_thread_flag(TIF_SIGPENDING);
365 if (!collect_signal(sig, pending, info))
373 * Dequeue a signal and return the element to the caller, which is
374 * expected to free it.
376 * All callers have to hold the siglock.
378 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
382 /* We only dequeue private signals from ourselves, we don't let
383 * signalfd steal them
385 signr = __dequeue_signal(&tsk->pending, mask, info);
387 signr = __dequeue_signal(&tsk->signal->shared_pending,
392 * itimers are process shared and we restart periodic
393 * itimers in the signal delivery path to prevent DoS
394 * attacks in the high resolution timer case. This is
395 * compliant with the old way of self restarting
396 * itimers, as the SIGALRM is a legacy signal and only
397 * queued once. Changing the restart behaviour to
398 * restart the timer in the signal dequeue path is
399 * reducing the timer noise on heavy loaded !highres
402 if (unlikely(signr == SIGALRM)) {
403 struct hrtimer *tmr = &tsk->signal->real_timer;
405 if (!hrtimer_is_queued(tmr) &&
406 tsk->signal->it_real_incr.tv64 != 0) {
407 hrtimer_forward(tmr, tmr->base->get_time(),
408 tsk->signal->it_real_incr);
409 hrtimer_restart(tmr);
418 if (unlikely(sig_kernel_stop(signr))) {
420 * Set a marker that we have dequeued a stop signal. Our
421 * caller might release the siglock and then the pending
422 * stop signal it is about to process is no longer in the
423 * pending bitmasks, but must still be cleared by a SIGCONT
424 * (and overruled by a SIGKILL). So those cases clear this
425 * shared flag after we've set it. Note that this flag may
426 * remain set after the signal we return is ignored or
427 * handled. That doesn't matter because its only purpose
428 * is to alert stop-signal processing code when another
429 * processor has come along and cleared the flag.
431 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
432 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
434 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
436 * Release the siglock to ensure proper locking order
437 * of timer locks outside of siglocks. Note, we leave
438 * irqs disabled here, since the posix-timers code is
439 * about to disable them again anyway.
441 spin_unlock(&tsk->sighand->siglock);
442 do_schedule_next_timer(info);
443 spin_lock(&tsk->sighand->siglock);
449 * Tell a process that it has a new active signal..
451 * NOTE! we rely on the previous spin_lock to
452 * lock interrupts for us! We can only be called with
453 * "siglock" held, and the local interrupt must
454 * have been disabled when that got acquired!
456 * No need to set need_resched since signal event passing
457 * goes through ->blocked
459 void signal_wake_up(struct task_struct *t, int resume)
463 set_tsk_thread_flag(t, TIF_SIGPENDING);
466 * For SIGKILL, we want to wake it up in the stopped/traced/killable
467 * case. We don't check t->state here because there is a race with it
468 * executing another processor and just now entering stopped state.
469 * By using wake_up_state, we ensure the process will wake up and
470 * handle its death signal.
472 mask = TASK_INTERRUPTIBLE;
474 mask |= TASK_WAKEKILL;
475 if (!wake_up_state(t, mask))
480 * Remove signals in mask from the pending set and queue.
481 * Returns 1 if any signals were found.
483 * All callers must be holding the siglock.
485 * This version takes a sigset mask and looks at all signals,
486 * not just those in the first mask word.
488 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
490 struct sigqueue *q, *n;
493 sigandsets(&m, mask, &s->signal);
494 if (sigisemptyset(&m))
497 signandsets(&s->signal, &s->signal, mask);
498 list_for_each_entry_safe(q, n, &s->list, list) {
499 if (sigismember(mask, q->info.si_signo)) {
500 list_del_init(&q->list);
507 * Remove signals in mask from the pending set and queue.
508 * Returns 1 if any signals were found.
510 * All callers must be holding the siglock.
512 static int rm_from_queue(unsigned long mask, struct sigpending *s)
514 struct sigqueue *q, *n;
516 if (!sigtestsetmask(&s->signal, mask))
519 sigdelsetmask(&s->signal, mask);
520 list_for_each_entry_safe(q, n, &s->list, list) {
521 if (q->info.si_signo < SIGRTMIN &&
522 (mask & sigmask(q->info.si_signo))) {
523 list_del_init(&q->list);
531 * Bad permissions for sending the signal
533 static int check_kill_permission(int sig, struct siginfo *info,
534 struct task_struct *t)
538 if (!valid_signal(sig))
541 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
544 error = audit_signal_info(sig, t); /* Let audit system see the signal */
548 if (((sig != SIGCONT) || (task_session_nr(current) != task_session_nr(t)))
549 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
550 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
551 && !capable(CAP_KILL))
554 return security_task_kill(t, info, sig, 0);
558 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
561 * Handle magic process-wide effects of stop/continue signals. Unlike
562 * the signal actions, these happen immediately at signal-generation
563 * time regardless of blocking, ignoring, or handling. This does the
564 * actual continuing for SIGCONT, but not the actual stopping for stop
565 * signals. The process stop is done as a signal action for SIG_DFL.
567 * Returns true if the signal should be actually delivered, otherwise
568 * it should be dropped.
570 static int prepare_signal(int sig, struct task_struct *p)
572 struct signal_struct *signal = p->signal;
573 struct task_struct *t;
575 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
577 * The process is in the middle of dying, nothing to do.
579 } else if (sig_kernel_stop(sig)) {
581 * This is a stop signal. Remove SIGCONT from all queues.
583 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
586 rm_from_queue(sigmask(SIGCONT), &t->pending);
587 } while_each_thread(p, t);
588 } else if (sig == SIGCONT) {
591 * Remove all stop signals from all queues,
592 * and wake all threads.
594 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
598 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
600 * If there is a handler for SIGCONT, we must make
601 * sure that no thread returns to user mode before
602 * we post the signal, in case it was the only
603 * thread eligible to run the signal handler--then
604 * it must not do anything between resuming and
605 * running the handler. With the TIF_SIGPENDING
606 * flag set, the thread will pause and acquire the
607 * siglock that we hold now and until we've queued
608 * the pending signal.
610 * Wake up the stopped thread _after_ setting
613 state = __TASK_STOPPED;
614 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
615 set_tsk_thread_flag(t, TIF_SIGPENDING);
616 state |= TASK_INTERRUPTIBLE;
618 wake_up_state(t, state);
619 } while_each_thread(p, t);
622 * Notify the parent with CLD_CONTINUED if we were stopped.
624 * If we were in the middle of a group stop, we pretend it
625 * was already finished, and then continued. Since SIGCHLD
626 * doesn't queue we report only CLD_STOPPED, as if the next
627 * CLD_CONTINUED was dropped.
630 if (signal->flags & SIGNAL_STOP_STOPPED)
631 why |= SIGNAL_CLD_CONTINUED;
632 else if (signal->group_stop_count)
633 why |= SIGNAL_CLD_STOPPED;
636 signal->flags = why | SIGNAL_STOP_CONTINUED;
637 signal->group_stop_count = 0;
638 signal->group_exit_code = 0;
641 * We are not stopped, but there could be a stop
642 * signal in the middle of being processed after
643 * being removed from the queue. Clear that too.
645 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
649 return !sig_ignored(p, sig);
653 * Test if P wants to take SIG. After we've checked all threads with this,
654 * it's equivalent to finding no threads not blocking SIG. Any threads not
655 * blocking SIG were ruled out because they are not running and already
656 * have pending signals. Such threads will dequeue from the shared queue
657 * as soon as they're available, so putting the signal on the shared queue
658 * will be equivalent to sending it to one such thread.
660 static inline int wants_signal(int sig, struct task_struct *p)
662 if (sigismember(&p->blocked, sig))
664 if (p->flags & PF_EXITING)
668 if (task_is_stopped_or_traced(p))
670 return task_curr(p) || !signal_pending(p);
673 static void complete_signal(int sig, struct task_struct *p, int group)
675 struct signal_struct *signal = p->signal;
676 struct task_struct *t;
679 * Now find a thread we can wake up to take the signal off the queue.
681 * If the main thread wants the signal, it gets first crack.
682 * Probably the least surprising to the average bear.
684 if (wants_signal(sig, p))
686 else if (!group || thread_group_empty(p))
688 * There is just one thread and it does not need to be woken.
689 * It will dequeue unblocked signals before it runs again.
694 * Otherwise try to find a suitable thread.
696 t = signal->curr_target;
697 while (!wants_signal(sig, t)) {
699 if (t == signal->curr_target)
701 * No thread needs to be woken.
702 * Any eligible threads will see
703 * the signal in the queue soon.
707 signal->curr_target = t;
711 * Found a killable thread. If the signal will be fatal,
712 * then start taking the whole group down immediately.
714 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
715 !sigismember(&t->real_blocked, sig) &&
716 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
718 * This signal will be fatal to the whole group.
720 if (!sig_kernel_coredump(sig)) {
722 * Start a group exit and wake everybody up.
723 * This way we don't have other threads
724 * running and doing things after a slower
725 * thread has the fatal signal pending.
727 signal->flags = SIGNAL_GROUP_EXIT;
728 signal->group_exit_code = sig;
729 signal->group_stop_count = 0;
732 sigaddset(&t->pending.signal, SIGKILL);
733 signal_wake_up(t, 1);
734 } while_each_thread(p, t);
740 * The signal is already in the shared-pending queue.
741 * Tell the chosen thread to wake up and dequeue it.
743 signal_wake_up(t, sig == SIGKILL);
747 static inline int legacy_queue(struct sigpending *signals, int sig)
749 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
752 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
755 struct sigpending *pending;
758 assert_spin_locked(&t->sighand->siglock);
759 if (!prepare_signal(sig, t))
762 pending = group ? &t->signal->shared_pending : &t->pending;
764 * Short-circuit ignored signals and support queuing
765 * exactly one non-rt signal, so that we can get more
766 * detailed information about the cause of the signal.
768 if (legacy_queue(pending, sig))
772 * Deliver the signal to listening signalfds. This must be called
773 * with the sighand lock held.
775 signalfd_notify(t, sig);
778 * fast-pathed signals for kernel-internal things like SIGSTOP
781 if (info == SEND_SIG_FORCED)
784 /* Real-time signals must be queued if sent by sigqueue, or
785 some other real-time mechanism. It is implementation
786 defined whether kill() does so. We attempt to do so, on
787 the principle of least surprise, but since kill is not
788 allowed to fail with EAGAIN when low on memory we just
789 make sure at least one signal gets delivered and don't
790 pass on the info struct. */
792 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
793 (is_si_special(info) ||
794 info->si_code >= 0)));
796 list_add_tail(&q->list, &pending->list);
797 switch ((unsigned long) info) {
798 case (unsigned long) SEND_SIG_NOINFO:
799 q->info.si_signo = sig;
800 q->info.si_errno = 0;
801 q->info.si_code = SI_USER;
802 q->info.si_pid = task_pid_vnr(current);
803 q->info.si_uid = current->uid;
805 case (unsigned long) SEND_SIG_PRIV:
806 q->info.si_signo = sig;
807 q->info.si_errno = 0;
808 q->info.si_code = SI_KERNEL;
813 copy_siginfo(&q->info, info);
816 } else if (!is_si_special(info)) {
817 if (sig >= SIGRTMIN && info->si_code != SI_USER)
819 * Queue overflow, abort. We may abort if the signal was rt
820 * and sent by user using something other than kill().
826 sigaddset(&pending->signal, sig);
827 complete_signal(sig, t, group);
831 int print_fatal_signals;
833 static void print_fatal_signal(struct pt_regs *regs, int signr)
835 printk("%s/%d: potentially unexpected fatal signal %d.\n",
836 current->comm, task_pid_nr(current), signr);
838 #if defined(__i386__) && !defined(__arch_um__)
839 printk("code at %08lx: ", regs->ip);
842 for (i = 0; i < 16; i++) {
845 __get_user(insn, (unsigned char *)(regs->ip + i));
846 printk("%02x ", insn);
854 static int __init setup_print_fatal_signals(char *str)
856 get_option (&str, &print_fatal_signals);
861 __setup("print-fatal-signals=", setup_print_fatal_signals);
864 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
866 return send_signal(sig, info, p, 1);
870 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
872 return send_signal(sig, info, t, 0);
876 * Force a signal that the process can't ignore: if necessary
877 * we unblock the signal and change any SIG_IGN to SIG_DFL.
879 * Note: If we unblock the signal, we always reset it to SIG_DFL,
880 * since we do not want to have a signal handler that was blocked
881 * be invoked when user space had explicitly blocked it.
883 * We don't want to have recursive SIGSEGV's etc, for example.
886 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
888 unsigned long int flags;
889 int ret, blocked, ignored;
890 struct k_sigaction *action;
892 spin_lock_irqsave(&t->sighand->siglock, flags);
893 action = &t->sighand->action[sig-1];
894 ignored = action->sa.sa_handler == SIG_IGN;
895 blocked = sigismember(&t->blocked, sig);
896 if (blocked || ignored) {
897 action->sa.sa_handler = SIG_DFL;
899 sigdelset(&t->blocked, sig);
900 recalc_sigpending_and_wake(t);
903 ret = specific_send_sig_info(sig, info, t);
904 spin_unlock_irqrestore(&t->sighand->siglock, flags);
910 force_sig_specific(int sig, struct task_struct *t)
912 force_sig_info(sig, SEND_SIG_FORCED, t);
916 * Nuke all other threads in the group.
918 void zap_other_threads(struct task_struct *p)
920 struct task_struct *t;
922 p->signal->group_stop_count = 0;
924 for (t = next_thread(p); t != p; t = next_thread(t)) {
926 * Don't bother with already dead threads
931 /* SIGKILL will be handled before any pending SIGSTOP */
932 sigaddset(&t->pending.signal, SIGKILL);
933 signal_wake_up(t, 1);
937 int __fatal_signal_pending(struct task_struct *tsk)
939 return sigismember(&tsk->pending.signal, SIGKILL);
941 EXPORT_SYMBOL(__fatal_signal_pending);
943 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
945 struct sighand_struct *sighand;
949 sighand = rcu_dereference(tsk->sighand);
950 if (unlikely(sighand == NULL))
953 spin_lock_irqsave(&sighand->siglock, *flags);
954 if (likely(sighand == tsk->sighand))
956 spin_unlock_irqrestore(&sighand->siglock, *flags);
963 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
968 ret = check_kill_permission(sig, info, p);
972 if (lock_task_sighand(p, &flags)) {
973 ret = __group_send_sig_info(sig, info, p);
974 unlock_task_sighand(p, &flags);
982 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
983 * control characters do (^C, ^Z etc)
986 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
988 struct task_struct *p = NULL;
993 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
994 int err = group_send_sig_info(sig, info, p);
997 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
998 return success ? 0 : retval;
1001 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1004 struct task_struct *p;
1008 p = pid_task(pid, PIDTYPE_PID);
1010 error = group_send_sig_info(sig, info, p);
1011 if (unlikely(error == -ESRCH))
1013 * The task was unhashed in between, try again.
1014 * If it is dead, pid_task() will return NULL,
1015 * if we race with de_thread() it will find the
1026 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1030 error = kill_pid_info(sig, info, find_vpid(pid));
1035 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1036 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1037 uid_t uid, uid_t euid, u32 secid)
1040 struct task_struct *p;
1042 if (!valid_signal(sig))
1045 read_lock(&tasklist_lock);
1046 p = pid_task(pid, PIDTYPE_PID);
1051 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1052 && (euid != p->suid) && (euid != p->uid)
1053 && (uid != p->suid) && (uid != p->uid)) {
1057 ret = security_task_kill(p, info, sig, secid);
1060 if (sig && p->sighand) {
1061 unsigned long flags;
1062 spin_lock_irqsave(&p->sighand->siglock, flags);
1063 ret = __group_send_sig_info(sig, info, p);
1064 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1067 read_unlock(&tasklist_lock);
1070 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1073 * kill_something_info() interprets pid in interesting ways just like kill(2).
1075 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1076 * is probably wrong. Should make it like BSD or SYSV.
1079 static int kill_something_info(int sig, struct siginfo *info, int pid)
1085 ret = kill_pid_info(sig, info, find_vpid(pid));
1090 read_lock(&tasklist_lock);
1092 ret = __kill_pgrp_info(sig, info,
1093 pid ? find_vpid(-pid) : task_pgrp(current));
1095 int retval = 0, count = 0;
1096 struct task_struct * p;
1098 for_each_process(p) {
1099 if (p->pid > 1 && !same_thread_group(p, current)) {
1100 int err = group_send_sig_info(sig, info, p);
1106 ret = count ? retval : -ESRCH;
1108 read_unlock(&tasklist_lock);
1114 * These are for backward compatibility with the rest of the kernel source.
1118 * The caller must ensure the task can't exit.
1121 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1124 unsigned long flags;
1127 * Make sure legacy kernel users don't send in bad values
1128 * (normal paths check this in check_kill_permission).
1130 if (!valid_signal(sig))
1133 spin_lock_irqsave(&p->sighand->siglock, flags);
1134 ret = specific_send_sig_info(sig, info, p);
1135 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1139 #define __si_special(priv) \
1140 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1143 send_sig(int sig, struct task_struct *p, int priv)
1145 return send_sig_info(sig, __si_special(priv), p);
1149 force_sig(int sig, struct task_struct *p)
1151 force_sig_info(sig, SEND_SIG_PRIV, p);
1155 * When things go south during signal handling, we
1156 * will force a SIGSEGV. And if the signal that caused
1157 * the problem was already a SIGSEGV, we'll want to
1158 * make sure we don't even try to deliver the signal..
1161 force_sigsegv(int sig, struct task_struct *p)
1163 if (sig == SIGSEGV) {
1164 unsigned long flags;
1165 spin_lock_irqsave(&p->sighand->siglock, flags);
1166 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1167 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1169 force_sig(SIGSEGV, p);
1173 int kill_pgrp(struct pid *pid, int sig, int priv)
1177 read_lock(&tasklist_lock);
1178 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1179 read_unlock(&tasklist_lock);
1183 EXPORT_SYMBOL(kill_pgrp);
1185 int kill_pid(struct pid *pid, int sig, int priv)
1187 return kill_pid_info(sig, __si_special(priv), pid);
1189 EXPORT_SYMBOL(kill_pid);
1192 kill_proc(pid_t pid, int sig, int priv)
1197 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1203 * These functions support sending signals using preallocated sigqueue
1204 * structures. This is needed "because realtime applications cannot
1205 * afford to lose notifications of asynchronous events, like timer
1206 * expirations or I/O completions". In the case of Posix Timers
1207 * we allocate the sigqueue structure from the timer_create. If this
1208 * allocation fails we are able to report the failure to the application
1209 * with an EAGAIN error.
1212 struct sigqueue *sigqueue_alloc(void)
1216 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1217 q->flags |= SIGQUEUE_PREALLOC;
1221 void sigqueue_free(struct sigqueue *q)
1223 unsigned long flags;
1224 spinlock_t *lock = ¤t->sighand->siglock;
1226 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1228 * If the signal is still pending remove it from the
1229 * pending queue. We must hold ->siglock while testing
1230 * q->list to serialize with collect_signal().
1232 spin_lock_irqsave(lock, flags);
1233 if (!list_empty(&q->list))
1234 list_del_init(&q->list);
1235 spin_unlock_irqrestore(lock, flags);
1237 q->flags &= ~SIGQUEUE_PREALLOC;
1241 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1243 int sig = q->info.si_signo;
1244 struct sigpending *pending;
1245 unsigned long flags;
1248 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1251 if (!likely(lock_task_sighand(t, &flags)))
1254 ret = 1; /* the signal is ignored */
1255 if (!prepare_signal(sig, t))
1259 if (unlikely(!list_empty(&q->list))) {
1261 * If an SI_TIMER entry is already queue just increment
1262 * the overrun count.
1264 BUG_ON(q->info.si_code != SI_TIMER);
1265 q->info.si_overrun++;
1269 signalfd_notify(t, sig);
1270 pending = group ? &t->signal->shared_pending : &t->pending;
1271 list_add_tail(&q->list, &pending->list);
1272 sigaddset(&pending->signal, sig);
1273 complete_signal(sig, t, group);
1275 unlock_task_sighand(t, &flags);
1281 * Wake up any threads in the parent blocked in wait* syscalls.
1283 static inline void __wake_up_parent(struct task_struct *p,
1284 struct task_struct *parent)
1286 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1290 * Let a parent know about the death of a child.
1291 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1294 void do_notify_parent(struct task_struct *tsk, int sig)
1296 struct siginfo info;
1297 unsigned long flags;
1298 struct sighand_struct *psig;
1302 /* do_notify_parent_cldstop should have been called instead. */
1303 BUG_ON(task_is_stopped_or_traced(tsk));
1305 BUG_ON(!tsk->ptrace &&
1306 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1308 info.si_signo = sig;
1311 * we are under tasklist_lock here so our parent is tied to
1312 * us and cannot exit and release its namespace.
1314 * the only it can is to switch its nsproxy with sys_unshare,
1315 * bu uncharing pid namespaces is not allowed, so we'll always
1316 * see relevant namespace
1318 * write_lock() currently calls preempt_disable() which is the
1319 * same as rcu_read_lock(), but according to Oleg, this is not
1320 * correct to rely on this
1323 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1326 info.si_uid = tsk->uid;
1328 /* FIXME: find out whether or not this is supposed to be c*time. */
1329 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1330 tsk->signal->utime));
1331 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1332 tsk->signal->stime));
1334 info.si_status = tsk->exit_code & 0x7f;
1335 if (tsk->exit_code & 0x80)
1336 info.si_code = CLD_DUMPED;
1337 else if (tsk->exit_code & 0x7f)
1338 info.si_code = CLD_KILLED;
1340 info.si_code = CLD_EXITED;
1341 info.si_status = tsk->exit_code >> 8;
1344 psig = tsk->parent->sighand;
1345 spin_lock_irqsave(&psig->siglock, flags);
1346 if (!tsk->ptrace && sig == SIGCHLD &&
1347 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1348 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1350 * We are exiting and our parent doesn't care. POSIX.1
1351 * defines special semantics for setting SIGCHLD to SIG_IGN
1352 * or setting the SA_NOCLDWAIT flag: we should be reaped
1353 * automatically and not left for our parent's wait4 call.
1354 * Rather than having the parent do it as a magic kind of
1355 * signal handler, we just set this to tell do_exit that we
1356 * can be cleaned up without becoming a zombie. Note that
1357 * we still call __wake_up_parent in this case, because a
1358 * blocked sys_wait4 might now return -ECHILD.
1360 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1361 * is implementation-defined: we do (if you don't want
1362 * it, just use SIG_IGN instead).
1364 tsk->exit_signal = -1;
1365 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1368 if (valid_signal(sig) && sig > 0)
1369 __group_send_sig_info(sig, &info, tsk->parent);
1370 __wake_up_parent(tsk, tsk->parent);
1371 spin_unlock_irqrestore(&psig->siglock, flags);
1374 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1376 struct siginfo info;
1377 unsigned long flags;
1378 struct task_struct *parent;
1379 struct sighand_struct *sighand;
1381 if (tsk->ptrace & PT_PTRACED)
1382 parent = tsk->parent;
1384 tsk = tsk->group_leader;
1385 parent = tsk->real_parent;
1388 info.si_signo = SIGCHLD;
1391 * see comment in do_notify_parent() abot the following 3 lines
1394 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1397 info.si_uid = tsk->uid;
1399 /* FIXME: find out whether or not this is supposed to be c*time. */
1400 info.si_utime = cputime_to_jiffies(tsk->utime);
1401 info.si_stime = cputime_to_jiffies(tsk->stime);
1406 info.si_status = SIGCONT;
1409 info.si_status = tsk->signal->group_exit_code & 0x7f;
1412 info.si_status = tsk->exit_code & 0x7f;
1418 sighand = parent->sighand;
1419 spin_lock_irqsave(&sighand->siglock, flags);
1420 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1421 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1422 __group_send_sig_info(SIGCHLD, &info, parent);
1424 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1426 __wake_up_parent(tsk, parent);
1427 spin_unlock_irqrestore(&sighand->siglock, flags);
1430 static inline int may_ptrace_stop(void)
1432 if (!likely(current->ptrace & PT_PTRACED))
1435 * Are we in the middle of do_coredump?
1436 * If so and our tracer is also part of the coredump stopping
1437 * is a deadlock situation, and pointless because our tracer
1438 * is dead so don't allow us to stop.
1439 * If SIGKILL was already sent before the caller unlocked
1440 * ->siglock we must see ->core_waiters != 0. Otherwise it
1441 * is safe to enter schedule().
1443 if (unlikely(current->mm->core_waiters) &&
1444 unlikely(current->mm == current->parent->mm))
1451 * Return nonzero if there is a SIGKILL that should be waking us up.
1452 * Called with the siglock held.
1454 static int sigkill_pending(struct task_struct *tsk)
1456 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1457 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1458 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1462 * This must be called with current->sighand->siglock held.
1464 * This should be the path for all ptrace stops.
1465 * We always set current->last_siginfo while stopped here.
1466 * That makes it a way to test a stopped process for
1467 * being ptrace-stopped vs being job-control-stopped.
1469 * If we actually decide not to stop at all because the tracer
1470 * is gone, we keep current->exit_code unless clear_code.
1472 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1476 if (arch_ptrace_stop_needed(exit_code, info)) {
1478 * The arch code has something special to do before a
1479 * ptrace stop. This is allowed to block, e.g. for faults
1480 * on user stack pages. We can't keep the siglock while
1481 * calling arch_ptrace_stop, so we must release it now.
1482 * To preserve proper semantics, we must do this before
1483 * any signal bookkeeping like checking group_stop_count.
1484 * Meanwhile, a SIGKILL could come in before we retake the
1485 * siglock. That must prevent us from sleeping in TASK_TRACED.
1486 * So after regaining the lock, we must check for SIGKILL.
1488 spin_unlock_irq(¤t->sighand->siglock);
1489 arch_ptrace_stop(exit_code, info);
1490 spin_lock_irq(¤t->sighand->siglock);
1491 killed = sigkill_pending(current);
1495 * If there is a group stop in progress,
1496 * we must participate in the bookkeeping.
1498 if (current->signal->group_stop_count > 0)
1499 --current->signal->group_stop_count;
1501 current->last_siginfo = info;
1502 current->exit_code = exit_code;
1504 /* Let the debugger run. */
1505 __set_current_state(TASK_TRACED);
1506 spin_unlock_irq(¤t->sighand->siglock);
1507 read_lock(&tasklist_lock);
1508 if (!unlikely(killed) && may_ptrace_stop()) {
1509 do_notify_parent_cldstop(current, CLD_TRAPPED);
1510 read_unlock(&tasklist_lock);
1514 * By the time we got the lock, our tracer went away.
1515 * Don't drop the lock yet, another tracer may come.
1517 __set_current_state(TASK_RUNNING);
1519 current->exit_code = 0;
1520 read_unlock(&tasklist_lock);
1524 * While in TASK_TRACED, we were considered "frozen enough".
1525 * Now that we woke up, it's crucial if we're supposed to be
1526 * frozen that we freeze now before running anything substantial.
1531 * We are back. Now reacquire the siglock before touching
1532 * last_siginfo, so that we are sure to have synchronized with
1533 * any signal-sending on another CPU that wants to examine it.
1535 spin_lock_irq(¤t->sighand->siglock);
1536 current->last_siginfo = NULL;
1539 * Queued signals ignored us while we were stopped for tracing.
1540 * So check for any that we should take before resuming user mode.
1541 * This sets TIF_SIGPENDING, but never clears it.
1543 recalc_sigpending_tsk(current);
1546 void ptrace_notify(int exit_code)
1550 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1552 memset(&info, 0, sizeof info);
1553 info.si_signo = SIGTRAP;
1554 info.si_code = exit_code;
1555 info.si_pid = task_pid_vnr(current);
1556 info.si_uid = current->uid;
1558 /* Let the debugger run. */
1559 spin_lock_irq(¤t->sighand->siglock);
1560 ptrace_stop(exit_code, 1, &info);
1561 spin_unlock_irq(¤t->sighand->siglock);
1565 finish_stop(int stop_count)
1568 * If there are no other threads in the group, or if there is
1569 * a group stop in progress and we are the last to stop,
1570 * report to the parent. When ptraced, every thread reports itself.
1572 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1573 read_lock(&tasklist_lock);
1574 do_notify_parent_cldstop(current, CLD_STOPPED);
1575 read_unlock(&tasklist_lock);
1580 } while (try_to_freeze());
1582 * Now we don't run again until continued.
1584 current->exit_code = 0;
1588 * This performs the stopping for SIGSTOP and other stop signals.
1589 * We have to stop all threads in the thread group.
1590 * Returns nonzero if we've actually stopped and released the siglock.
1591 * Returns zero if we didn't stop and still hold the siglock.
1593 static int do_signal_stop(int signr)
1595 struct signal_struct *sig = current->signal;
1598 if (sig->group_stop_count > 0) {
1600 * There is a group stop in progress. We don't need to
1601 * start another one.
1603 stop_count = --sig->group_stop_count;
1605 struct task_struct *t;
1607 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1608 unlikely(signal_group_exit(sig)))
1611 * There is no group stop already in progress.
1612 * We must initiate one now.
1614 sig->group_exit_code = signr;
1617 for (t = next_thread(current); t != current; t = next_thread(t))
1619 * Setting state to TASK_STOPPED for a group
1620 * stop is always done with the siglock held,
1621 * so this check has no races.
1623 if (!(t->flags & PF_EXITING) &&
1624 !task_is_stopped_or_traced(t)) {
1626 signal_wake_up(t, 0);
1628 sig->group_stop_count = stop_count;
1631 if (stop_count == 0)
1632 sig->flags = SIGNAL_STOP_STOPPED;
1633 current->exit_code = sig->group_exit_code;
1634 __set_current_state(TASK_STOPPED);
1636 spin_unlock_irq(¤t->sighand->siglock);
1637 finish_stop(stop_count);
1641 static int ptrace_signal(int signr, siginfo_t *info,
1642 struct pt_regs *regs, void *cookie)
1644 if (!(current->ptrace & PT_PTRACED))
1647 ptrace_signal_deliver(regs, cookie);
1649 /* Let the debugger run. */
1650 ptrace_stop(signr, 0, info);
1652 /* We're back. Did the debugger cancel the sig? */
1653 signr = current->exit_code;
1657 current->exit_code = 0;
1659 /* Update the siginfo structure if the signal has
1660 changed. If the debugger wanted something
1661 specific in the siginfo structure then it should
1662 have updated *info via PTRACE_SETSIGINFO. */
1663 if (signr != info->si_signo) {
1664 info->si_signo = signr;
1666 info->si_code = SI_USER;
1667 info->si_pid = task_pid_vnr(current->parent);
1668 info->si_uid = current->parent->uid;
1671 /* If the (new) signal is now blocked, requeue it. */
1672 if (sigismember(¤t->blocked, signr)) {
1673 specific_send_sig_info(signr, info, current);
1680 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1681 struct pt_regs *regs, void *cookie)
1683 struct sighand_struct *sighand = current->sighand;
1684 struct signal_struct *signal = current->signal;
1689 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1690 * While in TASK_STOPPED, we were considered "frozen enough".
1691 * Now that we woke up, it's crucial if we're supposed to be
1692 * frozen that we freeze now before running anything substantial.
1696 spin_lock_irq(&sighand->siglock);
1698 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1699 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1700 ? CLD_CONTINUED : CLD_STOPPED;
1701 signal->flags &= ~SIGNAL_CLD_MASK;
1702 spin_unlock_irq(&sighand->siglock);
1704 read_lock(&tasklist_lock);
1705 do_notify_parent_cldstop(current->group_leader, why);
1706 read_unlock(&tasklist_lock);
1711 struct k_sigaction *ka;
1713 if (unlikely(signal->group_stop_count > 0) &&
1717 signr = dequeue_signal(current, ¤t->blocked, info);
1719 break; /* will return 0 */
1721 if (signr != SIGKILL) {
1722 signr = ptrace_signal(signr, info, regs, cookie);
1727 ka = &sighand->action[signr-1];
1728 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1730 if (ka->sa.sa_handler != SIG_DFL) {
1731 /* Run the handler. */
1734 if (ka->sa.sa_flags & SA_ONESHOT)
1735 ka->sa.sa_handler = SIG_DFL;
1737 break; /* will return non-zero "signr" value */
1741 * Now we are doing the default action for this signal.
1743 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1747 * Global init gets no signals it doesn't want.
1749 if (is_global_init(current))
1752 if (sig_kernel_stop(signr)) {
1754 * The default action is to stop all threads in
1755 * the thread group. The job control signals
1756 * do nothing in an orphaned pgrp, but SIGSTOP
1757 * always works. Note that siglock needs to be
1758 * dropped during the call to is_orphaned_pgrp()
1759 * because of lock ordering with tasklist_lock.
1760 * This allows an intervening SIGCONT to be posted.
1761 * We need to check for that and bail out if necessary.
1763 if (signr != SIGSTOP) {
1764 spin_unlock_irq(&sighand->siglock);
1766 /* signals can be posted during this window */
1768 if (is_current_pgrp_orphaned())
1771 spin_lock_irq(&sighand->siglock);
1774 if (likely(do_signal_stop(signr))) {
1775 /* It released the siglock. */
1780 * We didn't actually stop, due to a race
1781 * with SIGCONT or something like that.
1786 spin_unlock_irq(&sighand->siglock);
1789 * Anything else is fatal, maybe with a core dump.
1791 current->flags |= PF_SIGNALED;
1793 if (sig_kernel_coredump(signr)) {
1794 if (print_fatal_signals)
1795 print_fatal_signal(regs, signr);
1797 * If it was able to dump core, this kills all
1798 * other threads in the group and synchronizes with
1799 * their demise. If we lost the race with another
1800 * thread getting here, it set group_exit_code
1801 * first and our do_group_exit call below will use
1802 * that value and ignore the one we pass it.
1804 do_coredump((long)signr, signr, regs);
1808 * Death signals, no core dump.
1810 do_group_exit(signr);
1813 spin_unlock_irq(&sighand->siglock);
1817 void exit_signals(struct task_struct *tsk)
1820 struct task_struct *t;
1822 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1823 tsk->flags |= PF_EXITING;
1827 spin_lock_irq(&tsk->sighand->siglock);
1829 * From now this task is not visible for group-wide signals,
1830 * see wants_signal(), do_signal_stop().
1832 tsk->flags |= PF_EXITING;
1833 if (!signal_pending(tsk))
1836 /* It could be that __group_complete_signal() choose us to
1837 * notify about group-wide signal. Another thread should be
1838 * woken now to take the signal since we will not.
1840 for (t = tsk; (t = next_thread(t)) != tsk; )
1841 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1842 recalc_sigpending_and_wake(t);
1844 if (unlikely(tsk->signal->group_stop_count) &&
1845 !--tsk->signal->group_stop_count) {
1846 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1850 spin_unlock_irq(&tsk->sighand->siglock);
1852 if (unlikely(group_stop)) {
1853 read_lock(&tasklist_lock);
1854 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1855 read_unlock(&tasklist_lock);
1859 EXPORT_SYMBOL(recalc_sigpending);
1860 EXPORT_SYMBOL_GPL(dequeue_signal);
1861 EXPORT_SYMBOL(flush_signals);
1862 EXPORT_SYMBOL(force_sig);
1863 EXPORT_SYMBOL(kill_proc);
1864 EXPORT_SYMBOL(ptrace_notify);
1865 EXPORT_SYMBOL(send_sig);
1866 EXPORT_SYMBOL(send_sig_info);
1867 EXPORT_SYMBOL(sigprocmask);
1868 EXPORT_SYMBOL(block_all_signals);
1869 EXPORT_SYMBOL(unblock_all_signals);
1873 * System call entry points.
1876 asmlinkage long sys_restart_syscall(void)
1878 struct restart_block *restart = ¤t_thread_info()->restart_block;
1879 return restart->fn(restart);
1882 long do_no_restart_syscall(struct restart_block *param)
1888 * We don't need to get the kernel lock - this is all local to this
1889 * particular thread.. (and that's good, because this is _heavily_
1890 * used by various programs)
1894 * This is also useful for kernel threads that want to temporarily
1895 * (or permanently) block certain signals.
1897 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1898 * interface happily blocks "unblockable" signals like SIGKILL
1901 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1905 spin_lock_irq(¤t->sighand->siglock);
1907 *oldset = current->blocked;
1912 sigorsets(¤t->blocked, ¤t->blocked, set);
1915 signandsets(¤t->blocked, ¤t->blocked, set);
1918 current->blocked = *set;
1923 recalc_sigpending();
1924 spin_unlock_irq(¤t->sighand->siglock);
1930 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1932 int error = -EINVAL;
1933 sigset_t old_set, new_set;
1935 /* XXX: Don't preclude handling different sized sigset_t's. */
1936 if (sigsetsize != sizeof(sigset_t))
1941 if (copy_from_user(&new_set, set, sizeof(*set)))
1943 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1945 error = sigprocmask(how, &new_set, &old_set);
1951 spin_lock_irq(¤t->sighand->siglock);
1952 old_set = current->blocked;
1953 spin_unlock_irq(¤t->sighand->siglock);
1957 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1965 long do_sigpending(void __user *set, unsigned long sigsetsize)
1967 long error = -EINVAL;
1970 if (sigsetsize > sizeof(sigset_t))
1973 spin_lock_irq(¤t->sighand->siglock);
1974 sigorsets(&pending, ¤t->pending.signal,
1975 ¤t->signal->shared_pending.signal);
1976 spin_unlock_irq(¤t->sighand->siglock);
1978 /* Outside the lock because only this thread touches it. */
1979 sigandsets(&pending, ¤t->blocked, &pending);
1982 if (!copy_to_user(set, &pending, sigsetsize))
1990 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
1992 return do_sigpending(set, sigsetsize);
1995 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
1997 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2001 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2003 if (from->si_code < 0)
2004 return __copy_to_user(to, from, sizeof(siginfo_t))
2007 * If you change siginfo_t structure, please be sure
2008 * this code is fixed accordingly.
2009 * Please remember to update the signalfd_copyinfo() function
2010 * inside fs/signalfd.c too, in case siginfo_t changes.
2011 * It should never copy any pad contained in the structure
2012 * to avoid security leaks, but must copy the generic
2013 * 3 ints plus the relevant union member.
2015 err = __put_user(from->si_signo, &to->si_signo);
2016 err |= __put_user(from->si_errno, &to->si_errno);
2017 err |= __put_user((short)from->si_code, &to->si_code);
2018 switch (from->si_code & __SI_MASK) {
2020 err |= __put_user(from->si_pid, &to->si_pid);
2021 err |= __put_user(from->si_uid, &to->si_uid);
2024 err |= __put_user(from->si_tid, &to->si_tid);
2025 err |= __put_user(from->si_overrun, &to->si_overrun);
2026 err |= __put_user(from->si_ptr, &to->si_ptr);
2029 err |= __put_user(from->si_band, &to->si_band);
2030 err |= __put_user(from->si_fd, &to->si_fd);
2033 err |= __put_user(from->si_addr, &to->si_addr);
2034 #ifdef __ARCH_SI_TRAPNO
2035 err |= __put_user(from->si_trapno, &to->si_trapno);
2039 err |= __put_user(from->si_pid, &to->si_pid);
2040 err |= __put_user(from->si_uid, &to->si_uid);
2041 err |= __put_user(from->si_status, &to->si_status);
2042 err |= __put_user(from->si_utime, &to->si_utime);
2043 err |= __put_user(from->si_stime, &to->si_stime);
2045 case __SI_RT: /* This is not generated by the kernel as of now. */
2046 case __SI_MESGQ: /* But this is */
2047 err |= __put_user(from->si_pid, &to->si_pid);
2048 err |= __put_user(from->si_uid, &to->si_uid);
2049 err |= __put_user(from->si_ptr, &to->si_ptr);
2051 default: /* this is just in case for now ... */
2052 err |= __put_user(from->si_pid, &to->si_pid);
2053 err |= __put_user(from->si_uid, &to->si_uid);
2062 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2063 siginfo_t __user *uinfo,
2064 const struct timespec __user *uts,
2073 /* XXX: Don't preclude handling different sized sigset_t's. */
2074 if (sigsetsize != sizeof(sigset_t))
2077 if (copy_from_user(&these, uthese, sizeof(these)))
2081 * Invert the set of allowed signals to get those we
2084 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2088 if (copy_from_user(&ts, uts, sizeof(ts)))
2090 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2095 spin_lock_irq(¤t->sighand->siglock);
2096 sig = dequeue_signal(current, &these, &info);
2098 timeout = MAX_SCHEDULE_TIMEOUT;
2100 timeout = (timespec_to_jiffies(&ts)
2101 + (ts.tv_sec || ts.tv_nsec));
2104 /* None ready -- temporarily unblock those we're
2105 * interested while we are sleeping in so that we'll
2106 * be awakened when they arrive. */
2107 current->real_blocked = current->blocked;
2108 sigandsets(¤t->blocked, ¤t->blocked, &these);
2109 recalc_sigpending();
2110 spin_unlock_irq(¤t->sighand->siglock);
2112 timeout = schedule_timeout_interruptible(timeout);
2114 spin_lock_irq(¤t->sighand->siglock);
2115 sig = dequeue_signal(current, &these, &info);
2116 current->blocked = current->real_blocked;
2117 siginitset(¤t->real_blocked, 0);
2118 recalc_sigpending();
2121 spin_unlock_irq(¤t->sighand->siglock);
2126 if (copy_siginfo_to_user(uinfo, &info))
2139 sys_kill(int pid, int sig)
2141 struct siginfo info;
2143 info.si_signo = sig;
2145 info.si_code = SI_USER;
2146 info.si_pid = task_tgid_vnr(current);
2147 info.si_uid = current->uid;
2149 return kill_something_info(sig, &info, pid);
2152 static int do_tkill(int tgid, int pid, int sig)
2155 struct siginfo info;
2156 struct task_struct *p;
2157 unsigned long flags;
2160 info.si_signo = sig;
2162 info.si_code = SI_TKILL;
2163 info.si_pid = task_tgid_vnr(current);
2164 info.si_uid = current->uid;
2167 p = find_task_by_vpid(pid);
2168 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2169 error = check_kill_permission(sig, &info, p);
2171 * The null signal is a permissions and process existence
2172 * probe. No signal is actually delivered.
2174 * If lock_task_sighand() fails we pretend the task dies
2175 * after receiving the signal. The window is tiny, and the
2176 * signal is private anyway.
2178 if (!error && sig && lock_task_sighand(p, &flags)) {
2179 error = specific_send_sig_info(sig, &info, p);
2180 unlock_task_sighand(p, &flags);
2189 * sys_tgkill - send signal to one specific thread
2190 * @tgid: the thread group ID of the thread
2191 * @pid: the PID of the thread
2192 * @sig: signal to be sent
2194 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2195 * exists but it's not belonging to the target process anymore. This
2196 * method solves the problem of threads exiting and PIDs getting reused.
2198 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2200 /* This is only valid for single tasks */
2201 if (pid <= 0 || tgid <= 0)
2204 return do_tkill(tgid, pid, sig);
2208 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2211 sys_tkill(int pid, int sig)
2213 /* This is only valid for single tasks */
2217 return do_tkill(0, pid, sig);
2221 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2225 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2228 /* Not even root can pretend to send signals from the kernel.
2229 Nor can they impersonate a kill(), which adds source info. */
2230 if (info.si_code >= 0)
2232 info.si_signo = sig;
2234 /* POSIX.1b doesn't mention process groups. */
2235 return kill_proc_info(sig, &info, pid);
2238 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2240 struct task_struct *t = current;
2241 struct k_sigaction *k;
2244 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2247 k = &t->sighand->action[sig-1];
2249 spin_lock_irq(¤t->sighand->siglock);
2254 sigdelsetmask(&act->sa.sa_mask,
2255 sigmask(SIGKILL) | sigmask(SIGSTOP));
2259 * "Setting a signal action to SIG_IGN for a signal that is
2260 * pending shall cause the pending signal to be discarded,
2261 * whether or not it is blocked."
2263 * "Setting a signal action to SIG_DFL for a signal that is
2264 * pending and whose default action is to ignore the signal
2265 * (for example, SIGCHLD), shall cause the pending signal to
2266 * be discarded, whether or not it is blocked"
2268 if (__sig_ignored(t, sig)) {
2270 sigaddset(&mask, sig);
2271 rm_from_queue_full(&mask, &t->signal->shared_pending);
2273 rm_from_queue_full(&mask, &t->pending);
2275 } while (t != current);
2279 spin_unlock_irq(¤t->sighand->siglock);
2284 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2290 oss.ss_sp = (void __user *) current->sas_ss_sp;
2291 oss.ss_size = current->sas_ss_size;
2292 oss.ss_flags = sas_ss_flags(sp);
2301 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2302 || __get_user(ss_sp, &uss->ss_sp)
2303 || __get_user(ss_flags, &uss->ss_flags)
2304 || __get_user(ss_size, &uss->ss_size))
2308 if (on_sig_stack(sp))
2314 * Note - this code used to test ss_flags incorrectly
2315 * old code may have been written using ss_flags==0
2316 * to mean ss_flags==SS_ONSTACK (as this was the only
2317 * way that worked) - this fix preserves that older
2320 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2323 if (ss_flags == SS_DISABLE) {
2328 if (ss_size < MINSIGSTKSZ)
2332 current->sas_ss_sp = (unsigned long) ss_sp;
2333 current->sas_ss_size = ss_size;
2338 if (copy_to_user(uoss, &oss, sizeof(oss)))
2347 #ifdef __ARCH_WANT_SYS_SIGPENDING
2350 sys_sigpending(old_sigset_t __user *set)
2352 return do_sigpending(set, sizeof(*set));
2357 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2358 /* Some platforms have their own version with special arguments others
2359 support only sys_rt_sigprocmask. */
2362 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2365 old_sigset_t old_set, new_set;
2369 if (copy_from_user(&new_set, set, sizeof(*set)))
2371 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2373 spin_lock_irq(¤t->sighand->siglock);
2374 old_set = current->blocked.sig[0];
2382 sigaddsetmask(¤t->blocked, new_set);
2385 sigdelsetmask(¤t->blocked, new_set);
2388 current->blocked.sig[0] = new_set;
2392 recalc_sigpending();
2393 spin_unlock_irq(¤t->sighand->siglock);
2399 old_set = current->blocked.sig[0];
2402 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2409 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2411 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2413 sys_rt_sigaction(int sig,
2414 const struct sigaction __user *act,
2415 struct sigaction __user *oact,
2418 struct k_sigaction new_sa, old_sa;
2421 /* XXX: Don't preclude handling different sized sigset_t's. */
2422 if (sigsetsize != sizeof(sigset_t))
2426 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2430 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2433 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2439 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2441 #ifdef __ARCH_WANT_SYS_SGETMASK
2444 * For backwards compatibility. Functionality superseded by sigprocmask.
2450 return current->blocked.sig[0];
2454 sys_ssetmask(int newmask)
2458 spin_lock_irq(¤t->sighand->siglock);
2459 old = current->blocked.sig[0];
2461 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2463 recalc_sigpending();
2464 spin_unlock_irq(¤t->sighand->siglock);
2468 #endif /* __ARCH_WANT_SGETMASK */
2470 #ifdef __ARCH_WANT_SYS_SIGNAL
2472 * For backwards compatibility. Functionality superseded by sigaction.
2474 asmlinkage unsigned long
2475 sys_signal(int sig, __sighandler_t handler)
2477 struct k_sigaction new_sa, old_sa;
2480 new_sa.sa.sa_handler = handler;
2481 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2482 sigemptyset(&new_sa.sa.sa_mask);
2484 ret = do_sigaction(sig, &new_sa, &old_sa);
2486 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2488 #endif /* __ARCH_WANT_SYS_SIGNAL */
2490 #ifdef __ARCH_WANT_SYS_PAUSE
2495 current->state = TASK_INTERRUPTIBLE;
2497 return -ERESTARTNOHAND;
2502 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2503 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2507 /* XXX: Don't preclude handling different sized sigset_t's. */
2508 if (sigsetsize != sizeof(sigset_t))
2511 if (copy_from_user(&newset, unewset, sizeof(newset)))
2513 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2515 spin_lock_irq(¤t->sighand->siglock);
2516 current->saved_sigmask = current->blocked;
2517 current->blocked = newset;
2518 recalc_sigpending();
2519 spin_unlock_irq(¤t->sighand->siglock);
2521 current->state = TASK_INTERRUPTIBLE;
2523 set_thread_flag(TIF_RESTORE_SIGMASK);
2524 return -ERESTARTNOHAND;
2526 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2528 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2533 void __init signals_init(void)
2535 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);