2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache *sigqueue_cachep;
42 static int __sig_ignored(struct task_struct *t, int sig)
46 /* Is it explicitly or implicitly ignored? */
48 handler = t->sighand->action[sig - 1].sa.sa_handler;
49 return handler == SIG_IGN ||
50 (handler == SIG_DFL && sig_kernel_ignore(sig));
53 static int sig_ignored(struct task_struct *t, int sig)
56 * Tracers always want to know about signals..
58 if (t->ptrace & PT_PTRACED)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
69 return __sig_ignored(t, sig);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
81 switch (_NSIG_WORDS) {
83 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
84 ready |= signal->sig[i] &~ blocked->sig[i];
87 case 4: ready = signal->sig[3] &~ blocked->sig[3];
88 ready |= signal->sig[2] &~ blocked->sig[2];
89 ready |= signal->sig[1] &~ blocked->sig[1];
90 ready |= signal->sig[0] &~ blocked->sig[0];
93 case 2: ready = signal->sig[1] &~ blocked->sig[1];
94 ready |= signal->sig[0] &~ blocked->sig[0];
97 case 1: ready = signal->sig[0] &~ blocked->sig[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct *t)
106 if (t->signal->group_stop_count > 0 ||
107 PENDING(&t->pending, &t->blocked) ||
108 PENDING(&t->signal->shared_pending, &t->blocked)) {
109 set_tsk_thread_flag(t, TIF_SIGPENDING);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct *t)
126 if (recalc_sigpending_tsk(t))
127 signal_wake_up(t, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current) && !freezing(current))
133 clear_thread_flag(TIF_SIGPENDING);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending *pending, sigset_t *mask)
141 unsigned long i, *s, *m, x;
144 s = pending->signal.sig;
146 switch (_NSIG_WORDS) {
148 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
149 if ((x = *s &~ *m) != 0) {
150 sig = ffz(~x) + i*_NSIG_BPW + 1;
155 case 2: if ((x = s[0] &~ m[0]) != 0)
157 else if ((x = s[1] &~ m[1]) != 0)
164 case 1: if ((x = *s &~ *m) != 0)
172 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
175 struct sigqueue *q = NULL;
176 struct user_struct *user;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user->sigpending);
185 if (override_rlimit ||
186 atomic_read(&user->sigpending) <=
187 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
188 q = kmem_cache_alloc(sigqueue_cachep, flags);
189 if (unlikely(q == NULL)) {
190 atomic_dec(&user->sigpending);
192 INIT_LIST_HEAD(&q->list);
194 q->user = get_uid(user);
199 static void __sigqueue_free(struct sigqueue *q)
201 if (q->flags & SIGQUEUE_PREALLOC)
203 atomic_dec(&q->user->sigpending);
205 kmem_cache_free(sigqueue_cachep, q);
208 void flush_sigqueue(struct sigpending *queue)
212 sigemptyset(&queue->signal);
213 while (!list_empty(&queue->list)) {
214 q = list_entry(queue->list.next, struct sigqueue , list);
215 list_del_init(&q->list);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct *t)
227 spin_lock_irqsave(&t->sighand->siglock, flags);
228 clear_tsk_thread_flag(t, TIF_SIGPENDING);
229 flush_sigqueue(&t->pending);
230 flush_sigqueue(&t->signal->shared_pending);
231 spin_unlock_irqrestore(&t->sighand->siglock, flags);
234 static void __flush_itimer_signals(struct sigpending *pending)
236 sigset_t signal, retain;
237 struct sigqueue *q, *n;
239 signal = pending->signal;
240 sigemptyset(&retain);
242 list_for_each_entry_safe(q, n, &pending->list, list) {
243 int sig = q->info.si_signo;
245 if (likely(q->info.si_code != SI_TIMER)) {
246 sigaddset(&retain, sig);
248 sigdelset(&signal, sig);
249 list_del_init(&q->list);
254 sigorsets(&pending->signal, &signal, &retain);
257 void flush_itimer_signals(void)
259 struct task_struct *tsk = current;
262 spin_lock_irqsave(&tsk->sighand->siglock, flags);
263 __flush_itimer_signals(&tsk->pending);
264 __flush_itimer_signals(&tsk->signal->shared_pending);
265 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
268 void ignore_signals(struct task_struct *t)
272 for (i = 0; i < _NSIG; ++i)
273 t->sighand->action[i].sa.sa_handler = SIG_IGN;
279 * Flush all handlers for a task.
283 flush_signal_handlers(struct task_struct *t, int force_default)
286 struct k_sigaction *ka = &t->sighand->action[0];
287 for (i = _NSIG ; i != 0 ; i--) {
288 if (force_default || ka->sa.sa_handler != SIG_IGN)
289 ka->sa.sa_handler = SIG_DFL;
291 sigemptyset(&ka->sa.sa_mask);
296 int unhandled_signal(struct task_struct *tsk, int sig)
298 if (is_global_init(tsk))
300 if (tsk->ptrace & PT_PTRACED)
302 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
303 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
307 /* Notify the system that a driver wants to block all signals for this
308 * process, and wants to be notified if any signals at all were to be
309 * sent/acted upon. If the notifier routine returns non-zero, then the
310 * signal will be acted upon after all. If the notifier routine returns 0,
311 * then then signal will be blocked. Only one block per process is
312 * allowed. priv is a pointer to private data that the notifier routine
313 * can use to determine if the signal should be blocked or not. */
316 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
320 spin_lock_irqsave(¤t->sighand->siglock, flags);
321 current->notifier_mask = mask;
322 current->notifier_data = priv;
323 current->notifier = notifier;
324 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
327 /* Notify the system that blocking has ended. */
330 unblock_all_signals(void)
334 spin_lock_irqsave(¤t->sighand->siglock, flags);
335 current->notifier = NULL;
336 current->notifier_data = NULL;
338 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
341 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
343 struct sigqueue *q, *first = NULL;
344 int still_pending = 0;
346 if (unlikely(!sigismember(&list->signal, sig)))
350 * Collect the siginfo appropriate to this signal. Check if
351 * there is another siginfo for the same signal.
353 list_for_each_entry(q, &list->list, list) {
354 if (q->info.si_signo == sig) {
363 list_del_init(&first->list);
364 copy_siginfo(info, &first->info);
365 __sigqueue_free(first);
367 sigdelset(&list->signal, sig);
370 /* Ok, it wasn't in the queue. This must be
371 a fast-pathed signal or we must have been
372 out of queue space. So zero out the info.
374 sigdelset(&list->signal, sig);
375 info->si_signo = sig;
384 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
387 int sig = next_signal(pending, mask);
390 if (current->notifier) {
391 if (sigismember(current->notifier_mask, sig)) {
392 if (!(current->notifier)(current->notifier_data)) {
393 clear_thread_flag(TIF_SIGPENDING);
399 if (!collect_signal(sig, pending, info))
407 * Dequeue a signal and return the element to the caller, which is
408 * expected to free it.
410 * All callers have to hold the siglock.
412 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
416 /* We only dequeue private signals from ourselves, we don't let
417 * signalfd steal them
419 signr = __dequeue_signal(&tsk->pending, mask, info);
421 signr = __dequeue_signal(&tsk->signal->shared_pending,
426 * itimers are process shared and we restart periodic
427 * itimers in the signal delivery path to prevent DoS
428 * attacks in the high resolution timer case. This is
429 * compliant with the old way of self restarting
430 * itimers, as the SIGALRM is a legacy signal and only
431 * queued once. Changing the restart behaviour to
432 * restart the timer in the signal dequeue path is
433 * reducing the timer noise on heavy loaded !highres
436 if (unlikely(signr == SIGALRM)) {
437 struct hrtimer *tmr = &tsk->signal->real_timer;
439 if (!hrtimer_is_queued(tmr) &&
440 tsk->signal->it_real_incr.tv64 != 0) {
441 hrtimer_forward(tmr, tmr->base->get_time(),
442 tsk->signal->it_real_incr);
443 hrtimer_restart(tmr);
452 if (unlikely(sig_kernel_stop(signr))) {
454 * Set a marker that we have dequeued a stop signal. Our
455 * caller might release the siglock and then the pending
456 * stop signal it is about to process is no longer in the
457 * pending bitmasks, but must still be cleared by a SIGCONT
458 * (and overruled by a SIGKILL). So those cases clear this
459 * shared flag after we've set it. Note that this flag may
460 * remain set after the signal we return is ignored or
461 * handled. That doesn't matter because its only purpose
462 * is to alert stop-signal processing code when another
463 * processor has come along and cleared the flag.
465 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
466 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
468 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
470 * Release the siglock to ensure proper locking order
471 * of timer locks outside of siglocks. Note, we leave
472 * irqs disabled here, since the posix-timers code is
473 * about to disable them again anyway.
475 spin_unlock(&tsk->sighand->siglock);
476 do_schedule_next_timer(info);
477 spin_lock(&tsk->sighand->siglock);
483 * Tell a process that it has a new active signal..
485 * NOTE! we rely on the previous spin_lock to
486 * lock interrupts for us! We can only be called with
487 * "siglock" held, and the local interrupt must
488 * have been disabled when that got acquired!
490 * No need to set need_resched since signal event passing
491 * goes through ->blocked
493 void signal_wake_up(struct task_struct *t, int resume)
497 set_tsk_thread_flag(t, TIF_SIGPENDING);
500 * For SIGKILL, we want to wake it up in the stopped/traced/killable
501 * case. We don't check t->state here because there is a race with it
502 * executing another processor and just now entering stopped state.
503 * By using wake_up_state, we ensure the process will wake up and
504 * handle its death signal.
506 mask = TASK_INTERRUPTIBLE;
508 mask |= TASK_WAKEKILL;
509 if (!wake_up_state(t, mask))
514 * Remove signals in mask from the pending set and queue.
515 * Returns 1 if any signals were found.
517 * All callers must be holding the siglock.
519 * This version takes a sigset mask and looks at all signals,
520 * not just those in the first mask word.
522 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
524 struct sigqueue *q, *n;
527 sigandsets(&m, mask, &s->signal);
528 if (sigisemptyset(&m))
531 signandsets(&s->signal, &s->signal, mask);
532 list_for_each_entry_safe(q, n, &s->list, list) {
533 if (sigismember(mask, q->info.si_signo)) {
534 list_del_init(&q->list);
541 * Remove signals in mask from the pending set and queue.
542 * Returns 1 if any signals were found.
544 * All callers must be holding the siglock.
546 static int rm_from_queue(unsigned long mask, struct sigpending *s)
548 struct sigqueue *q, *n;
550 if (!sigtestsetmask(&s->signal, mask))
553 sigdelsetmask(&s->signal, mask);
554 list_for_each_entry_safe(q, n, &s->list, list) {
555 if (q->info.si_signo < SIGRTMIN &&
556 (mask & sigmask(q->info.si_signo))) {
557 list_del_init(&q->list);
565 * Bad permissions for sending the signal
567 static int check_kill_permission(int sig, struct siginfo *info,
568 struct task_struct *t)
573 if (!valid_signal(sig))
576 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
579 error = audit_signal_info(sig, t); /* Let audit system see the signal */
583 if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
584 (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
585 !capable(CAP_KILL)) {
588 sid = task_session(t);
590 * We don't return the error if sid == NULL. The
591 * task was unhashed, the caller must notice this.
593 if (!sid || sid == task_session(current))
600 return security_task_kill(t, info, sig, 0);
604 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
607 * Handle magic process-wide effects of stop/continue signals. Unlike
608 * the signal actions, these happen immediately at signal-generation
609 * time regardless of blocking, ignoring, or handling. This does the
610 * actual continuing for SIGCONT, but not the actual stopping for stop
611 * signals. The process stop is done as a signal action for SIG_DFL.
613 * Returns true if the signal should be actually delivered, otherwise
614 * it should be dropped.
616 static int prepare_signal(int sig, struct task_struct *p)
618 struct signal_struct *signal = p->signal;
619 struct task_struct *t;
621 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
623 * The process is in the middle of dying, nothing to do.
625 } else if (sig_kernel_stop(sig)) {
627 * This is a stop signal. Remove SIGCONT from all queues.
629 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
632 rm_from_queue(sigmask(SIGCONT), &t->pending);
633 } while_each_thread(p, t);
634 } else if (sig == SIGCONT) {
637 * Remove all stop signals from all queues,
638 * and wake all threads.
640 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
644 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
646 * If there is a handler for SIGCONT, we must make
647 * sure that no thread returns to user mode before
648 * we post the signal, in case it was the only
649 * thread eligible to run the signal handler--then
650 * it must not do anything between resuming and
651 * running the handler. With the TIF_SIGPENDING
652 * flag set, the thread will pause and acquire the
653 * siglock that we hold now and until we've queued
654 * the pending signal.
656 * Wake up the stopped thread _after_ setting
659 state = __TASK_STOPPED;
660 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
661 set_tsk_thread_flag(t, TIF_SIGPENDING);
662 state |= TASK_INTERRUPTIBLE;
664 wake_up_state(t, state);
665 } while_each_thread(p, t);
668 * Notify the parent with CLD_CONTINUED if we were stopped.
670 * If we were in the middle of a group stop, we pretend it
671 * was already finished, and then continued. Since SIGCHLD
672 * doesn't queue we report only CLD_STOPPED, as if the next
673 * CLD_CONTINUED was dropped.
676 if (signal->flags & SIGNAL_STOP_STOPPED)
677 why |= SIGNAL_CLD_CONTINUED;
678 else if (signal->group_stop_count)
679 why |= SIGNAL_CLD_STOPPED;
683 * The first thread which returns from finish_stop()
684 * will take ->siglock, notice SIGNAL_CLD_MASK, and
685 * notify its parent. See get_signal_to_deliver().
687 signal->flags = why | SIGNAL_STOP_CONTINUED;
688 signal->group_stop_count = 0;
689 signal->group_exit_code = 0;
692 * We are not stopped, but there could be a stop
693 * signal in the middle of being processed after
694 * being removed from the queue. Clear that too.
696 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
700 return !sig_ignored(p, sig);
704 * Test if P wants to take SIG. After we've checked all threads with this,
705 * it's equivalent to finding no threads not blocking SIG. Any threads not
706 * blocking SIG were ruled out because they are not running and already
707 * have pending signals. Such threads will dequeue from the shared queue
708 * as soon as they're available, so putting the signal on the shared queue
709 * will be equivalent to sending it to one such thread.
711 static inline int wants_signal(int sig, struct task_struct *p)
713 if (sigismember(&p->blocked, sig))
715 if (p->flags & PF_EXITING)
719 if (task_is_stopped_or_traced(p))
721 return task_curr(p) || !signal_pending(p);
724 static void complete_signal(int sig, struct task_struct *p, int group)
726 struct signal_struct *signal = p->signal;
727 struct task_struct *t;
730 * Now find a thread we can wake up to take the signal off the queue.
732 * If the main thread wants the signal, it gets first crack.
733 * Probably the least surprising to the average bear.
735 if (wants_signal(sig, p))
737 else if (!group || thread_group_empty(p))
739 * There is just one thread and it does not need to be woken.
740 * It will dequeue unblocked signals before it runs again.
745 * Otherwise try to find a suitable thread.
747 t = signal->curr_target;
748 while (!wants_signal(sig, t)) {
750 if (t == signal->curr_target)
752 * No thread needs to be woken.
753 * Any eligible threads will see
754 * the signal in the queue soon.
758 signal->curr_target = t;
762 * Found a killable thread. If the signal will be fatal,
763 * then start taking the whole group down immediately.
765 if (sig_fatal(p, sig) &&
766 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
767 !sigismember(&t->real_blocked, sig) &&
768 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
770 * This signal will be fatal to the whole group.
772 if (!sig_kernel_coredump(sig)) {
774 * Start a group exit and wake everybody up.
775 * This way we don't have other threads
776 * running and doing things after a slower
777 * thread has the fatal signal pending.
779 signal->flags = SIGNAL_GROUP_EXIT;
780 signal->group_exit_code = sig;
781 signal->group_stop_count = 0;
784 sigaddset(&t->pending.signal, SIGKILL);
785 signal_wake_up(t, 1);
786 } while_each_thread(p, t);
792 * The signal is already in the shared-pending queue.
793 * Tell the chosen thread to wake up and dequeue it.
795 signal_wake_up(t, sig == SIGKILL);
799 static inline int legacy_queue(struct sigpending *signals, int sig)
801 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
804 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
807 struct sigpending *pending;
810 assert_spin_locked(&t->sighand->siglock);
811 if (!prepare_signal(sig, t))
814 pending = group ? &t->signal->shared_pending : &t->pending;
816 * Short-circuit ignored signals and support queuing
817 * exactly one non-rt signal, so that we can get more
818 * detailed information about the cause of the signal.
820 if (legacy_queue(pending, sig))
823 * fast-pathed signals for kernel-internal things like SIGSTOP
826 if (info == SEND_SIG_FORCED)
829 /* Real-time signals must be queued if sent by sigqueue, or
830 some other real-time mechanism. It is implementation
831 defined whether kill() does so. We attempt to do so, on
832 the principle of least surprise, but since kill is not
833 allowed to fail with EAGAIN when low on memory we just
834 make sure at least one signal gets delivered and don't
835 pass on the info struct. */
837 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
838 (is_si_special(info) ||
839 info->si_code >= 0)));
841 list_add_tail(&q->list, &pending->list);
842 switch ((unsigned long) info) {
843 case (unsigned long) SEND_SIG_NOINFO:
844 q->info.si_signo = sig;
845 q->info.si_errno = 0;
846 q->info.si_code = SI_USER;
847 q->info.si_pid = task_pid_vnr(current);
848 q->info.si_uid = current->uid;
850 case (unsigned long) SEND_SIG_PRIV:
851 q->info.si_signo = sig;
852 q->info.si_errno = 0;
853 q->info.si_code = SI_KERNEL;
858 copy_siginfo(&q->info, info);
861 } else if (!is_si_special(info)) {
862 if (sig >= SIGRTMIN && info->si_code != SI_USER)
864 * Queue overflow, abort. We may abort if the signal was rt
865 * and sent by user using something other than kill().
871 signalfd_notify(t, sig);
872 sigaddset(&pending->signal, sig);
873 complete_signal(sig, t, group);
877 int print_fatal_signals;
879 static void print_fatal_signal(struct pt_regs *regs, int signr)
881 printk("%s/%d: potentially unexpected fatal signal %d.\n",
882 current->comm, task_pid_nr(current), signr);
884 #if defined(__i386__) && !defined(__arch_um__)
885 printk("code at %08lx: ", regs->ip);
888 for (i = 0; i < 16; i++) {
891 __get_user(insn, (unsigned char *)(regs->ip + i));
892 printk("%02x ", insn);
900 static int __init setup_print_fatal_signals(char *str)
902 get_option (&str, &print_fatal_signals);
907 __setup("print-fatal-signals=", setup_print_fatal_signals);
910 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
912 return send_signal(sig, info, p, 1);
916 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
918 return send_signal(sig, info, t, 0);
922 * Force a signal that the process can't ignore: if necessary
923 * we unblock the signal and change any SIG_IGN to SIG_DFL.
925 * Note: If we unblock the signal, we always reset it to SIG_DFL,
926 * since we do not want to have a signal handler that was blocked
927 * be invoked when user space had explicitly blocked it.
929 * We don't want to have recursive SIGSEGV's etc, for example,
930 * that is why we also clear SIGNAL_UNKILLABLE.
933 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
935 unsigned long int flags;
936 int ret, blocked, ignored;
937 struct k_sigaction *action;
939 spin_lock_irqsave(&t->sighand->siglock, flags);
940 action = &t->sighand->action[sig-1];
941 ignored = action->sa.sa_handler == SIG_IGN;
942 blocked = sigismember(&t->blocked, sig);
943 if (blocked || ignored) {
944 action->sa.sa_handler = SIG_DFL;
946 sigdelset(&t->blocked, sig);
947 recalc_sigpending_and_wake(t);
950 if (action->sa.sa_handler == SIG_DFL)
951 t->signal->flags &= ~SIGNAL_UNKILLABLE;
952 ret = specific_send_sig_info(sig, info, t);
953 spin_unlock_irqrestore(&t->sighand->siglock, flags);
959 force_sig_specific(int sig, struct task_struct *t)
961 force_sig_info(sig, SEND_SIG_FORCED, t);
965 * Nuke all other threads in the group.
967 void zap_other_threads(struct task_struct *p)
969 struct task_struct *t;
971 p->signal->group_stop_count = 0;
973 for (t = next_thread(p); t != p; t = next_thread(t)) {
975 * Don't bother with already dead threads
980 /* SIGKILL will be handled before any pending SIGSTOP */
981 sigaddset(&t->pending.signal, SIGKILL);
982 signal_wake_up(t, 1);
986 int __fatal_signal_pending(struct task_struct *tsk)
988 return sigismember(&tsk->pending.signal, SIGKILL);
990 EXPORT_SYMBOL(__fatal_signal_pending);
992 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
994 struct sighand_struct *sighand;
998 sighand = rcu_dereference(tsk->sighand);
999 if (unlikely(sighand == NULL))
1002 spin_lock_irqsave(&sighand->siglock, *flags);
1003 if (likely(sighand == tsk->sighand))
1005 spin_unlock_irqrestore(&sighand->siglock, *flags);
1012 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1014 unsigned long flags;
1017 ret = check_kill_permission(sig, info, p);
1021 if (lock_task_sighand(p, &flags)) {
1022 ret = __group_send_sig_info(sig, info, p);
1023 unlock_task_sighand(p, &flags);
1031 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1032 * control characters do (^C, ^Z etc)
1035 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1037 struct task_struct *p = NULL;
1038 int retval, success;
1042 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1043 int err = group_send_sig_info(sig, info, p);
1046 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1047 return success ? 0 : retval;
1050 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1053 struct task_struct *p;
1057 p = pid_task(pid, PIDTYPE_PID);
1059 error = group_send_sig_info(sig, info, p);
1060 if (unlikely(error == -ESRCH))
1062 * The task was unhashed in between, try again.
1063 * If it is dead, pid_task() will return NULL,
1064 * if we race with de_thread() it will find the
1075 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1079 error = kill_pid_info(sig, info, find_vpid(pid));
1084 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1085 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1086 uid_t uid, uid_t euid, u32 secid)
1089 struct task_struct *p;
1091 if (!valid_signal(sig))
1094 read_lock(&tasklist_lock);
1095 p = pid_task(pid, PIDTYPE_PID);
1100 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1101 && (euid != p->suid) && (euid != p->uid)
1102 && (uid != p->suid) && (uid != p->uid)) {
1106 ret = security_task_kill(p, info, sig, secid);
1109 if (sig && p->sighand) {
1110 unsigned long flags;
1111 spin_lock_irqsave(&p->sighand->siglock, flags);
1112 ret = __group_send_sig_info(sig, info, p);
1113 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1116 read_unlock(&tasklist_lock);
1119 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1122 * kill_something_info() interprets pid in interesting ways just like kill(2).
1124 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1125 * is probably wrong. Should make it like BSD or SYSV.
1128 static int kill_something_info(int sig, struct siginfo *info, int pid)
1134 ret = kill_pid_info(sig, info, find_vpid(pid));
1139 read_lock(&tasklist_lock);
1141 ret = __kill_pgrp_info(sig, info,
1142 pid ? find_vpid(-pid) : task_pgrp(current));
1144 int retval = 0, count = 0;
1145 struct task_struct * p;
1147 for_each_process(p) {
1148 if (p->pid > 1 && !same_thread_group(p, current)) {
1149 int err = group_send_sig_info(sig, info, p);
1155 ret = count ? retval : -ESRCH;
1157 read_unlock(&tasklist_lock);
1163 * These are for backward compatibility with the rest of the kernel source.
1167 * The caller must ensure the task can't exit.
1170 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1173 unsigned long flags;
1176 * Make sure legacy kernel users don't send in bad values
1177 * (normal paths check this in check_kill_permission).
1179 if (!valid_signal(sig))
1182 spin_lock_irqsave(&p->sighand->siglock, flags);
1183 ret = specific_send_sig_info(sig, info, p);
1184 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1188 #define __si_special(priv) \
1189 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1192 send_sig(int sig, struct task_struct *p, int priv)
1194 return send_sig_info(sig, __si_special(priv), p);
1198 force_sig(int sig, struct task_struct *p)
1200 force_sig_info(sig, SEND_SIG_PRIV, p);
1204 * When things go south during signal handling, we
1205 * will force a SIGSEGV. And if the signal that caused
1206 * the problem was already a SIGSEGV, we'll want to
1207 * make sure we don't even try to deliver the signal..
1210 force_sigsegv(int sig, struct task_struct *p)
1212 if (sig == SIGSEGV) {
1213 unsigned long flags;
1214 spin_lock_irqsave(&p->sighand->siglock, flags);
1215 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1216 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1218 force_sig(SIGSEGV, p);
1222 int kill_pgrp(struct pid *pid, int sig, int priv)
1226 read_lock(&tasklist_lock);
1227 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1228 read_unlock(&tasklist_lock);
1232 EXPORT_SYMBOL(kill_pgrp);
1234 int kill_pid(struct pid *pid, int sig, int priv)
1236 return kill_pid_info(sig, __si_special(priv), pid);
1238 EXPORT_SYMBOL(kill_pid);
1241 kill_proc(pid_t pid, int sig, int priv)
1246 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1252 * These functions support sending signals using preallocated sigqueue
1253 * structures. This is needed "because realtime applications cannot
1254 * afford to lose notifications of asynchronous events, like timer
1255 * expirations or I/O completions". In the case of Posix Timers
1256 * we allocate the sigqueue structure from the timer_create. If this
1257 * allocation fails we are able to report the failure to the application
1258 * with an EAGAIN error.
1261 struct sigqueue *sigqueue_alloc(void)
1265 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1266 q->flags |= SIGQUEUE_PREALLOC;
1270 void sigqueue_free(struct sigqueue *q)
1272 unsigned long flags;
1273 spinlock_t *lock = ¤t->sighand->siglock;
1275 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1277 * We must hold ->siglock while testing q->list
1278 * to serialize with collect_signal() or with
1279 * __exit_signal()->flush_sigqueue().
1281 spin_lock_irqsave(lock, flags);
1282 q->flags &= ~SIGQUEUE_PREALLOC;
1284 * If it is queued it will be freed when dequeued,
1285 * like the "regular" sigqueue.
1287 if (!list_empty(&q->list))
1289 spin_unlock_irqrestore(lock, flags);
1295 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1297 int sig = q->info.si_signo;
1298 struct sigpending *pending;
1299 unsigned long flags;
1302 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1305 if (!likely(lock_task_sighand(t, &flags)))
1308 ret = 1; /* the signal is ignored */
1309 if (!prepare_signal(sig, t))
1313 if (unlikely(!list_empty(&q->list))) {
1315 * If an SI_TIMER entry is already queue just increment
1316 * the overrun count.
1318 BUG_ON(q->info.si_code != SI_TIMER);
1319 q->info.si_overrun++;
1323 signalfd_notify(t, sig);
1324 pending = group ? &t->signal->shared_pending : &t->pending;
1325 list_add_tail(&q->list, &pending->list);
1326 sigaddset(&pending->signal, sig);
1327 complete_signal(sig, t, group);
1329 unlock_task_sighand(t, &flags);
1335 * Wake up any threads in the parent blocked in wait* syscalls.
1337 static inline void __wake_up_parent(struct task_struct *p,
1338 struct task_struct *parent)
1340 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1344 * Let a parent know about the death of a child.
1345 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1348 void do_notify_parent(struct task_struct *tsk, int sig)
1350 struct siginfo info;
1351 unsigned long flags;
1352 struct sighand_struct *psig;
1356 /* do_notify_parent_cldstop should have been called instead. */
1357 BUG_ON(task_is_stopped_or_traced(tsk));
1359 BUG_ON(!tsk->ptrace &&
1360 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1362 info.si_signo = sig;
1365 * we are under tasklist_lock here so our parent is tied to
1366 * us and cannot exit and release its namespace.
1368 * the only it can is to switch its nsproxy with sys_unshare,
1369 * bu uncharing pid namespaces is not allowed, so we'll always
1370 * see relevant namespace
1372 * write_lock() currently calls preempt_disable() which is the
1373 * same as rcu_read_lock(), but according to Oleg, this is not
1374 * correct to rely on this
1377 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1380 info.si_uid = tsk->uid;
1382 /* FIXME: find out whether or not this is supposed to be c*time. */
1383 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1384 tsk->signal->utime));
1385 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1386 tsk->signal->stime));
1388 info.si_status = tsk->exit_code & 0x7f;
1389 if (tsk->exit_code & 0x80)
1390 info.si_code = CLD_DUMPED;
1391 else if (tsk->exit_code & 0x7f)
1392 info.si_code = CLD_KILLED;
1394 info.si_code = CLD_EXITED;
1395 info.si_status = tsk->exit_code >> 8;
1398 psig = tsk->parent->sighand;
1399 spin_lock_irqsave(&psig->siglock, flags);
1400 if (!tsk->ptrace && sig == SIGCHLD &&
1401 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1402 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1404 * We are exiting and our parent doesn't care. POSIX.1
1405 * defines special semantics for setting SIGCHLD to SIG_IGN
1406 * or setting the SA_NOCLDWAIT flag: we should be reaped
1407 * automatically and not left for our parent's wait4 call.
1408 * Rather than having the parent do it as a magic kind of
1409 * signal handler, we just set this to tell do_exit that we
1410 * can be cleaned up without becoming a zombie. Note that
1411 * we still call __wake_up_parent in this case, because a
1412 * blocked sys_wait4 might now return -ECHILD.
1414 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1415 * is implementation-defined: we do (if you don't want
1416 * it, just use SIG_IGN instead).
1418 tsk->exit_signal = -1;
1419 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1422 if (valid_signal(sig) && sig > 0)
1423 __group_send_sig_info(sig, &info, tsk->parent);
1424 __wake_up_parent(tsk, tsk->parent);
1425 spin_unlock_irqrestore(&psig->siglock, flags);
1428 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1430 struct siginfo info;
1431 unsigned long flags;
1432 struct task_struct *parent;
1433 struct sighand_struct *sighand;
1435 if (tsk->ptrace & PT_PTRACED)
1436 parent = tsk->parent;
1438 tsk = tsk->group_leader;
1439 parent = tsk->real_parent;
1442 info.si_signo = SIGCHLD;
1445 * see comment in do_notify_parent() abot the following 3 lines
1448 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1451 info.si_uid = tsk->uid;
1453 /* FIXME: find out whether or not this is supposed to be c*time. */
1454 info.si_utime = cputime_to_jiffies(tsk->utime);
1455 info.si_stime = cputime_to_jiffies(tsk->stime);
1460 info.si_status = SIGCONT;
1463 info.si_status = tsk->signal->group_exit_code & 0x7f;
1466 info.si_status = tsk->exit_code & 0x7f;
1472 sighand = parent->sighand;
1473 spin_lock_irqsave(&sighand->siglock, flags);
1474 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1475 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1476 __group_send_sig_info(SIGCHLD, &info, parent);
1478 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1480 __wake_up_parent(tsk, parent);
1481 spin_unlock_irqrestore(&sighand->siglock, flags);
1484 static inline int may_ptrace_stop(void)
1486 if (!likely(current->ptrace & PT_PTRACED))
1489 * Are we in the middle of do_coredump?
1490 * If so and our tracer is also part of the coredump stopping
1491 * is a deadlock situation, and pointless because our tracer
1492 * is dead so don't allow us to stop.
1493 * If SIGKILL was already sent before the caller unlocked
1494 * ->siglock we must see ->core_waiters != 0. Otherwise it
1495 * is safe to enter schedule().
1497 if (unlikely(current->mm->core_waiters) &&
1498 unlikely(current->mm == current->parent->mm))
1505 * Return nonzero if there is a SIGKILL that should be waking us up.
1506 * Called with the siglock held.
1508 static int sigkill_pending(struct task_struct *tsk)
1510 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1511 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1512 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1516 * This must be called with current->sighand->siglock held.
1518 * This should be the path for all ptrace stops.
1519 * We always set current->last_siginfo while stopped here.
1520 * That makes it a way to test a stopped process for
1521 * being ptrace-stopped vs being job-control-stopped.
1523 * If we actually decide not to stop at all because the tracer
1524 * is gone, we keep current->exit_code unless clear_code.
1526 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1530 if (arch_ptrace_stop_needed(exit_code, info)) {
1532 * The arch code has something special to do before a
1533 * ptrace stop. This is allowed to block, e.g. for faults
1534 * on user stack pages. We can't keep the siglock while
1535 * calling arch_ptrace_stop, so we must release it now.
1536 * To preserve proper semantics, we must do this before
1537 * any signal bookkeeping like checking group_stop_count.
1538 * Meanwhile, a SIGKILL could come in before we retake the
1539 * siglock. That must prevent us from sleeping in TASK_TRACED.
1540 * So after regaining the lock, we must check for SIGKILL.
1542 spin_unlock_irq(¤t->sighand->siglock);
1543 arch_ptrace_stop(exit_code, info);
1544 spin_lock_irq(¤t->sighand->siglock);
1545 killed = sigkill_pending(current);
1549 * If there is a group stop in progress,
1550 * we must participate in the bookkeeping.
1552 if (current->signal->group_stop_count > 0)
1553 --current->signal->group_stop_count;
1555 current->last_siginfo = info;
1556 current->exit_code = exit_code;
1558 /* Let the debugger run. */
1559 __set_current_state(TASK_TRACED);
1560 spin_unlock_irq(¤t->sighand->siglock);
1561 read_lock(&tasklist_lock);
1562 if (!unlikely(killed) && may_ptrace_stop()) {
1563 do_notify_parent_cldstop(current, CLD_TRAPPED);
1564 read_unlock(&tasklist_lock);
1568 * By the time we got the lock, our tracer went away.
1569 * Don't drop the lock yet, another tracer may come.
1571 __set_current_state(TASK_RUNNING);
1573 current->exit_code = 0;
1574 read_unlock(&tasklist_lock);
1578 * While in TASK_TRACED, we were considered "frozen enough".
1579 * Now that we woke up, it's crucial if we're supposed to be
1580 * frozen that we freeze now before running anything substantial.
1585 * We are back. Now reacquire the siglock before touching
1586 * last_siginfo, so that we are sure to have synchronized with
1587 * any signal-sending on another CPU that wants to examine it.
1589 spin_lock_irq(¤t->sighand->siglock);
1590 current->last_siginfo = NULL;
1593 * Queued signals ignored us while we were stopped for tracing.
1594 * So check for any that we should take before resuming user mode.
1595 * This sets TIF_SIGPENDING, but never clears it.
1597 recalc_sigpending_tsk(current);
1600 void ptrace_notify(int exit_code)
1604 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1606 memset(&info, 0, sizeof info);
1607 info.si_signo = SIGTRAP;
1608 info.si_code = exit_code;
1609 info.si_pid = task_pid_vnr(current);
1610 info.si_uid = current->uid;
1612 /* Let the debugger run. */
1613 spin_lock_irq(¤t->sighand->siglock);
1614 ptrace_stop(exit_code, 1, &info);
1615 spin_unlock_irq(¤t->sighand->siglock);
1619 finish_stop(int stop_count)
1622 * If there are no other threads in the group, or if there is
1623 * a group stop in progress and we are the last to stop,
1624 * report to the parent. When ptraced, every thread reports itself.
1626 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1627 read_lock(&tasklist_lock);
1628 do_notify_parent_cldstop(current, CLD_STOPPED);
1629 read_unlock(&tasklist_lock);
1634 } while (try_to_freeze());
1636 * Now we don't run again until continued.
1638 current->exit_code = 0;
1642 * This performs the stopping for SIGSTOP and other stop signals.
1643 * We have to stop all threads in the thread group.
1644 * Returns nonzero if we've actually stopped and released the siglock.
1645 * Returns zero if we didn't stop and still hold the siglock.
1647 static int do_signal_stop(int signr)
1649 struct signal_struct *sig = current->signal;
1652 if (sig->group_stop_count > 0) {
1654 * There is a group stop in progress. We don't need to
1655 * start another one.
1657 stop_count = --sig->group_stop_count;
1659 struct task_struct *t;
1661 if (unlikely((sig->flags & (SIGNAL_STOP_DEQUEUED | SIGNAL_UNKILLABLE))
1662 != SIGNAL_STOP_DEQUEUED) ||
1663 unlikely(signal_group_exit(sig)))
1666 * There is no group stop already in progress.
1667 * We must initiate one now.
1669 sig->group_exit_code = signr;
1672 for (t = next_thread(current); t != current; t = next_thread(t))
1674 * Setting state to TASK_STOPPED for a group
1675 * stop is always done with the siglock held,
1676 * so this check has no races.
1678 if (!(t->flags & PF_EXITING) &&
1679 !task_is_stopped_or_traced(t)) {
1681 signal_wake_up(t, 0);
1683 sig->group_stop_count = stop_count;
1686 if (stop_count == 0)
1687 sig->flags = SIGNAL_STOP_STOPPED;
1688 current->exit_code = sig->group_exit_code;
1689 __set_current_state(TASK_STOPPED);
1691 spin_unlock_irq(¤t->sighand->siglock);
1692 finish_stop(stop_count);
1696 static int ptrace_signal(int signr, siginfo_t *info,
1697 struct pt_regs *regs, void *cookie)
1699 if (!(current->ptrace & PT_PTRACED))
1702 ptrace_signal_deliver(regs, cookie);
1704 /* Let the debugger run. */
1705 ptrace_stop(signr, 0, info);
1707 /* We're back. Did the debugger cancel the sig? */
1708 signr = current->exit_code;
1712 current->exit_code = 0;
1714 /* Update the siginfo structure if the signal has
1715 changed. If the debugger wanted something
1716 specific in the siginfo structure then it should
1717 have updated *info via PTRACE_SETSIGINFO. */
1718 if (signr != info->si_signo) {
1719 info->si_signo = signr;
1721 info->si_code = SI_USER;
1722 info->si_pid = task_pid_vnr(current->parent);
1723 info->si_uid = current->parent->uid;
1726 /* If the (new) signal is now blocked, requeue it. */
1727 if (sigismember(¤t->blocked, signr)) {
1728 specific_send_sig_info(signr, info, current);
1735 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1736 struct pt_regs *regs, void *cookie)
1738 struct sighand_struct *sighand = current->sighand;
1739 struct signal_struct *signal = current->signal;
1744 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1745 * While in TASK_STOPPED, we were considered "frozen enough".
1746 * Now that we woke up, it's crucial if we're supposed to be
1747 * frozen that we freeze now before running anything substantial.
1751 spin_lock_irq(&sighand->siglock);
1753 * Every stopped thread goes here after wakeup. Check to see if
1754 * we should notify the parent, prepare_signal(SIGCONT) encodes
1755 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1757 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1758 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1759 ? CLD_CONTINUED : CLD_STOPPED;
1760 signal->flags &= ~SIGNAL_CLD_MASK;
1761 spin_unlock_irq(&sighand->siglock);
1763 read_lock(&tasklist_lock);
1764 do_notify_parent_cldstop(current->group_leader, why);
1765 read_unlock(&tasklist_lock);
1770 struct k_sigaction *ka;
1772 if (unlikely(signal->group_stop_count > 0) &&
1776 signr = dequeue_signal(current, ¤t->blocked, info);
1778 break; /* will return 0 */
1780 if (signr != SIGKILL) {
1781 signr = ptrace_signal(signr, info, regs, cookie);
1786 ka = &sighand->action[signr-1];
1787 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1789 if (ka->sa.sa_handler != SIG_DFL) {
1790 /* Run the handler. */
1793 if (ka->sa.sa_flags & SA_ONESHOT)
1794 ka->sa.sa_handler = SIG_DFL;
1796 break; /* will return non-zero "signr" value */
1800 * Now we are doing the default action for this signal.
1802 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1806 * Global init gets no signals it doesn't want.
1808 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1809 !signal_group_exit(signal))
1812 if (sig_kernel_stop(signr)) {
1814 * The default action is to stop all threads in
1815 * the thread group. The job control signals
1816 * do nothing in an orphaned pgrp, but SIGSTOP
1817 * always works. Note that siglock needs to be
1818 * dropped during the call to is_orphaned_pgrp()
1819 * because of lock ordering with tasklist_lock.
1820 * This allows an intervening SIGCONT to be posted.
1821 * We need to check for that and bail out if necessary.
1823 if (signr != SIGSTOP) {
1824 spin_unlock_irq(&sighand->siglock);
1826 /* signals can be posted during this window */
1828 if (is_current_pgrp_orphaned())
1831 spin_lock_irq(&sighand->siglock);
1834 if (likely(do_signal_stop(signr))) {
1835 /* It released the siglock. */
1840 * We didn't actually stop, due to a race
1841 * with SIGCONT or something like that.
1846 spin_unlock_irq(&sighand->siglock);
1849 * Anything else is fatal, maybe with a core dump.
1851 current->flags |= PF_SIGNALED;
1853 if (sig_kernel_coredump(signr)) {
1854 if (print_fatal_signals)
1855 print_fatal_signal(regs, signr);
1857 * If it was able to dump core, this kills all
1858 * other threads in the group and synchronizes with
1859 * their demise. If we lost the race with another
1860 * thread getting here, it set group_exit_code
1861 * first and our do_group_exit call below will use
1862 * that value and ignore the one we pass it.
1864 do_coredump((long)signr, signr, regs);
1868 * Death signals, no core dump.
1870 do_group_exit(signr);
1873 spin_unlock_irq(&sighand->siglock);
1877 void exit_signals(struct task_struct *tsk)
1880 struct task_struct *t;
1882 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1883 tsk->flags |= PF_EXITING;
1887 spin_lock_irq(&tsk->sighand->siglock);
1889 * From now this task is not visible for group-wide signals,
1890 * see wants_signal(), do_signal_stop().
1892 tsk->flags |= PF_EXITING;
1893 if (!signal_pending(tsk))
1896 /* It could be that __group_complete_signal() choose us to
1897 * notify about group-wide signal. Another thread should be
1898 * woken now to take the signal since we will not.
1900 for (t = tsk; (t = next_thread(t)) != tsk; )
1901 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1902 recalc_sigpending_and_wake(t);
1904 if (unlikely(tsk->signal->group_stop_count) &&
1905 !--tsk->signal->group_stop_count) {
1906 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1910 spin_unlock_irq(&tsk->sighand->siglock);
1912 if (unlikely(group_stop)) {
1913 read_lock(&tasklist_lock);
1914 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1915 read_unlock(&tasklist_lock);
1919 EXPORT_SYMBOL(recalc_sigpending);
1920 EXPORT_SYMBOL_GPL(dequeue_signal);
1921 EXPORT_SYMBOL(flush_signals);
1922 EXPORT_SYMBOL(force_sig);
1923 EXPORT_SYMBOL(kill_proc);
1924 EXPORT_SYMBOL(ptrace_notify);
1925 EXPORT_SYMBOL(send_sig);
1926 EXPORT_SYMBOL(send_sig_info);
1927 EXPORT_SYMBOL(sigprocmask);
1928 EXPORT_SYMBOL(block_all_signals);
1929 EXPORT_SYMBOL(unblock_all_signals);
1933 * System call entry points.
1936 asmlinkage long sys_restart_syscall(void)
1938 struct restart_block *restart = ¤t_thread_info()->restart_block;
1939 return restart->fn(restart);
1942 long do_no_restart_syscall(struct restart_block *param)
1948 * We don't need to get the kernel lock - this is all local to this
1949 * particular thread.. (and that's good, because this is _heavily_
1950 * used by various programs)
1954 * This is also useful for kernel threads that want to temporarily
1955 * (or permanently) block certain signals.
1957 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1958 * interface happily blocks "unblockable" signals like SIGKILL
1961 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1965 spin_lock_irq(¤t->sighand->siglock);
1967 *oldset = current->blocked;
1972 sigorsets(¤t->blocked, ¤t->blocked, set);
1975 signandsets(¤t->blocked, ¤t->blocked, set);
1978 current->blocked = *set;
1983 recalc_sigpending();
1984 spin_unlock_irq(¤t->sighand->siglock);
1990 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1992 int error = -EINVAL;
1993 sigset_t old_set, new_set;
1995 /* XXX: Don't preclude handling different sized sigset_t's. */
1996 if (sigsetsize != sizeof(sigset_t))
2001 if (copy_from_user(&new_set, set, sizeof(*set)))
2003 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2005 error = sigprocmask(how, &new_set, &old_set);
2011 spin_lock_irq(¤t->sighand->siglock);
2012 old_set = current->blocked;
2013 spin_unlock_irq(¤t->sighand->siglock);
2017 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2025 long do_sigpending(void __user *set, unsigned long sigsetsize)
2027 long error = -EINVAL;
2030 if (sigsetsize > sizeof(sigset_t))
2033 spin_lock_irq(¤t->sighand->siglock);
2034 sigorsets(&pending, ¤t->pending.signal,
2035 ¤t->signal->shared_pending.signal);
2036 spin_unlock_irq(¤t->sighand->siglock);
2038 /* Outside the lock because only this thread touches it. */
2039 sigandsets(&pending, ¤t->blocked, &pending);
2042 if (!copy_to_user(set, &pending, sigsetsize))
2050 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2052 return do_sigpending(set, sigsetsize);
2055 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2057 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2061 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2063 if (from->si_code < 0)
2064 return __copy_to_user(to, from, sizeof(siginfo_t))
2067 * If you change siginfo_t structure, please be sure
2068 * this code is fixed accordingly.
2069 * Please remember to update the signalfd_copyinfo() function
2070 * inside fs/signalfd.c too, in case siginfo_t changes.
2071 * It should never copy any pad contained in the structure
2072 * to avoid security leaks, but must copy the generic
2073 * 3 ints plus the relevant union member.
2075 err = __put_user(from->si_signo, &to->si_signo);
2076 err |= __put_user(from->si_errno, &to->si_errno);
2077 err |= __put_user((short)from->si_code, &to->si_code);
2078 switch (from->si_code & __SI_MASK) {
2080 err |= __put_user(from->si_pid, &to->si_pid);
2081 err |= __put_user(from->si_uid, &to->si_uid);
2084 err |= __put_user(from->si_tid, &to->si_tid);
2085 err |= __put_user(from->si_overrun, &to->si_overrun);
2086 err |= __put_user(from->si_ptr, &to->si_ptr);
2089 err |= __put_user(from->si_band, &to->si_band);
2090 err |= __put_user(from->si_fd, &to->si_fd);
2093 err |= __put_user(from->si_addr, &to->si_addr);
2094 #ifdef __ARCH_SI_TRAPNO
2095 err |= __put_user(from->si_trapno, &to->si_trapno);
2099 err |= __put_user(from->si_pid, &to->si_pid);
2100 err |= __put_user(from->si_uid, &to->si_uid);
2101 err |= __put_user(from->si_status, &to->si_status);
2102 err |= __put_user(from->si_utime, &to->si_utime);
2103 err |= __put_user(from->si_stime, &to->si_stime);
2105 case __SI_RT: /* This is not generated by the kernel as of now. */
2106 case __SI_MESGQ: /* But this is */
2107 err |= __put_user(from->si_pid, &to->si_pid);
2108 err |= __put_user(from->si_uid, &to->si_uid);
2109 err |= __put_user(from->si_ptr, &to->si_ptr);
2111 default: /* this is just in case for now ... */
2112 err |= __put_user(from->si_pid, &to->si_pid);
2113 err |= __put_user(from->si_uid, &to->si_uid);
2122 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2123 siginfo_t __user *uinfo,
2124 const struct timespec __user *uts,
2133 /* XXX: Don't preclude handling different sized sigset_t's. */
2134 if (sigsetsize != sizeof(sigset_t))
2137 if (copy_from_user(&these, uthese, sizeof(these)))
2141 * Invert the set of allowed signals to get those we
2144 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2148 if (copy_from_user(&ts, uts, sizeof(ts)))
2150 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2155 spin_lock_irq(¤t->sighand->siglock);
2156 sig = dequeue_signal(current, &these, &info);
2158 timeout = MAX_SCHEDULE_TIMEOUT;
2160 timeout = (timespec_to_jiffies(&ts)
2161 + (ts.tv_sec || ts.tv_nsec));
2164 /* None ready -- temporarily unblock those we're
2165 * interested while we are sleeping in so that we'll
2166 * be awakened when they arrive. */
2167 current->real_blocked = current->blocked;
2168 sigandsets(¤t->blocked, ¤t->blocked, &these);
2169 recalc_sigpending();
2170 spin_unlock_irq(¤t->sighand->siglock);
2172 timeout = schedule_timeout_interruptible(timeout);
2174 spin_lock_irq(¤t->sighand->siglock);
2175 sig = dequeue_signal(current, &these, &info);
2176 current->blocked = current->real_blocked;
2177 siginitset(¤t->real_blocked, 0);
2178 recalc_sigpending();
2181 spin_unlock_irq(¤t->sighand->siglock);
2186 if (copy_siginfo_to_user(uinfo, &info))
2199 sys_kill(int pid, int sig)
2201 struct siginfo info;
2203 info.si_signo = sig;
2205 info.si_code = SI_USER;
2206 info.si_pid = task_tgid_vnr(current);
2207 info.si_uid = current->uid;
2209 return kill_something_info(sig, &info, pid);
2212 static int do_tkill(int tgid, int pid, int sig)
2215 struct siginfo info;
2216 struct task_struct *p;
2217 unsigned long flags;
2220 info.si_signo = sig;
2222 info.si_code = SI_TKILL;
2223 info.si_pid = task_tgid_vnr(current);
2224 info.si_uid = current->uid;
2227 p = find_task_by_vpid(pid);
2228 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2229 error = check_kill_permission(sig, &info, p);
2231 * The null signal is a permissions and process existence
2232 * probe. No signal is actually delivered.
2234 * If lock_task_sighand() fails we pretend the task dies
2235 * after receiving the signal. The window is tiny, and the
2236 * signal is private anyway.
2238 if (!error && sig && lock_task_sighand(p, &flags)) {
2239 error = specific_send_sig_info(sig, &info, p);
2240 unlock_task_sighand(p, &flags);
2249 * sys_tgkill - send signal to one specific thread
2250 * @tgid: the thread group ID of the thread
2251 * @pid: the PID of the thread
2252 * @sig: signal to be sent
2254 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2255 * exists but it's not belonging to the target process anymore. This
2256 * method solves the problem of threads exiting and PIDs getting reused.
2258 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2260 /* This is only valid for single tasks */
2261 if (pid <= 0 || tgid <= 0)
2264 return do_tkill(tgid, pid, sig);
2268 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2271 sys_tkill(int pid, int sig)
2273 /* This is only valid for single tasks */
2277 return do_tkill(0, pid, sig);
2281 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2285 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2288 /* Not even root can pretend to send signals from the kernel.
2289 Nor can they impersonate a kill(), which adds source info. */
2290 if (info.si_code >= 0)
2292 info.si_signo = sig;
2294 /* POSIX.1b doesn't mention process groups. */
2295 return kill_proc_info(sig, &info, pid);
2298 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2300 struct task_struct *t = current;
2301 struct k_sigaction *k;
2304 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2307 k = &t->sighand->action[sig-1];
2309 spin_lock_irq(¤t->sighand->siglock);
2314 sigdelsetmask(&act->sa.sa_mask,
2315 sigmask(SIGKILL) | sigmask(SIGSTOP));
2319 * "Setting a signal action to SIG_IGN for a signal that is
2320 * pending shall cause the pending signal to be discarded,
2321 * whether or not it is blocked."
2323 * "Setting a signal action to SIG_DFL for a signal that is
2324 * pending and whose default action is to ignore the signal
2325 * (for example, SIGCHLD), shall cause the pending signal to
2326 * be discarded, whether or not it is blocked"
2328 if (__sig_ignored(t, sig)) {
2330 sigaddset(&mask, sig);
2331 rm_from_queue_full(&mask, &t->signal->shared_pending);
2333 rm_from_queue_full(&mask, &t->pending);
2335 } while (t != current);
2339 spin_unlock_irq(¤t->sighand->siglock);
2344 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2350 oss.ss_sp = (void __user *) current->sas_ss_sp;
2351 oss.ss_size = current->sas_ss_size;
2352 oss.ss_flags = sas_ss_flags(sp);
2361 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2362 || __get_user(ss_sp, &uss->ss_sp)
2363 || __get_user(ss_flags, &uss->ss_flags)
2364 || __get_user(ss_size, &uss->ss_size))
2368 if (on_sig_stack(sp))
2374 * Note - this code used to test ss_flags incorrectly
2375 * old code may have been written using ss_flags==0
2376 * to mean ss_flags==SS_ONSTACK (as this was the only
2377 * way that worked) - this fix preserves that older
2380 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2383 if (ss_flags == SS_DISABLE) {
2388 if (ss_size < MINSIGSTKSZ)
2392 current->sas_ss_sp = (unsigned long) ss_sp;
2393 current->sas_ss_size = ss_size;
2398 if (copy_to_user(uoss, &oss, sizeof(oss)))
2407 #ifdef __ARCH_WANT_SYS_SIGPENDING
2410 sys_sigpending(old_sigset_t __user *set)
2412 return do_sigpending(set, sizeof(*set));
2417 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2418 /* Some platforms have their own version with special arguments others
2419 support only sys_rt_sigprocmask. */
2422 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2425 old_sigset_t old_set, new_set;
2429 if (copy_from_user(&new_set, set, sizeof(*set)))
2431 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2433 spin_lock_irq(¤t->sighand->siglock);
2434 old_set = current->blocked.sig[0];
2442 sigaddsetmask(¤t->blocked, new_set);
2445 sigdelsetmask(¤t->blocked, new_set);
2448 current->blocked.sig[0] = new_set;
2452 recalc_sigpending();
2453 spin_unlock_irq(¤t->sighand->siglock);
2459 old_set = current->blocked.sig[0];
2462 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2469 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2471 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2473 sys_rt_sigaction(int sig,
2474 const struct sigaction __user *act,
2475 struct sigaction __user *oact,
2478 struct k_sigaction new_sa, old_sa;
2481 /* XXX: Don't preclude handling different sized sigset_t's. */
2482 if (sigsetsize != sizeof(sigset_t))
2486 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2490 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2493 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2499 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2501 #ifdef __ARCH_WANT_SYS_SGETMASK
2504 * For backwards compatibility. Functionality superseded by sigprocmask.
2510 return current->blocked.sig[0];
2514 sys_ssetmask(int newmask)
2518 spin_lock_irq(¤t->sighand->siglock);
2519 old = current->blocked.sig[0];
2521 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2523 recalc_sigpending();
2524 spin_unlock_irq(¤t->sighand->siglock);
2528 #endif /* __ARCH_WANT_SGETMASK */
2530 #ifdef __ARCH_WANT_SYS_SIGNAL
2532 * For backwards compatibility. Functionality superseded by sigaction.
2534 asmlinkage unsigned long
2535 sys_signal(int sig, __sighandler_t handler)
2537 struct k_sigaction new_sa, old_sa;
2540 new_sa.sa.sa_handler = handler;
2541 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2542 sigemptyset(&new_sa.sa.sa_mask);
2544 ret = do_sigaction(sig, &new_sa, &old_sa);
2546 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2548 #endif /* __ARCH_WANT_SYS_SIGNAL */
2550 #ifdef __ARCH_WANT_SYS_PAUSE
2555 current->state = TASK_INTERRUPTIBLE;
2557 return -ERESTARTNOHAND;
2562 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2563 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2567 /* XXX: Don't preclude handling different sized sigset_t's. */
2568 if (sigsetsize != sizeof(sigset_t))
2571 if (copy_from_user(&newset, unewset, sizeof(newset)))
2573 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2575 spin_lock_irq(¤t->sighand->siglock);
2576 current->saved_sigmask = current->blocked;
2577 current->blocked = newset;
2578 recalc_sigpending();
2579 spin_unlock_irq(¤t->sighand->siglock);
2581 current->state = TASK_INTERRUPTIBLE;
2583 set_restore_sigmask();
2584 return -ERESTARTNOHAND;
2586 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2588 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2593 void __init signals_init(void)
2595 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);