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/tracehook.h>
26 #include <linux/capability.h>
27 #include <linux/freezer.h>
28 #include <linux/pid_namespace.h>
29 #include <linux/nsproxy.h>
30 #include <trace/sched.h>
32 #include <asm/param.h>
33 #include <asm/uaccess.h>
34 #include <asm/unistd.h>
35 #include <asm/siginfo.h>
36 #include "audit.h" /* audit_signal_info() */
39 * SLAB caches for signal bits.
42 static struct kmem_cache *sigqueue_cachep;
44 static void __user *sig_handler(struct task_struct *t, int sig)
46 return t->sighand->action[sig - 1].sa.sa_handler;
49 static int sig_handler_ignored(void __user *handler, int sig)
51 /* Is it explicitly or implicitly ignored? */
52 return handler == SIG_IGN ||
53 (handler == SIG_DFL && sig_kernel_ignore(sig));
56 static int sig_ignored(struct task_struct *t, int sig)
61 * Blocked signals are never ignored, since the
62 * signal handler may change by the time it is
65 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
68 handler = sig_handler(t, sig);
69 if (!sig_handler_ignored(handler, sig))
73 * Tracers may want to know about even ignored signals.
75 return !tracehook_consider_ignored_signal(t, sig, handler);
79 * Re-calculate pending state from the set of locally pending
80 * signals, globally pending signals, and blocked signals.
82 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
87 switch (_NSIG_WORDS) {
89 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
90 ready |= signal->sig[i] &~ blocked->sig[i];
93 case 4: ready = signal->sig[3] &~ blocked->sig[3];
94 ready |= signal->sig[2] &~ blocked->sig[2];
95 ready |= signal->sig[1] &~ blocked->sig[1];
96 ready |= signal->sig[0] &~ blocked->sig[0];
99 case 2: ready = signal->sig[1] &~ blocked->sig[1];
100 ready |= signal->sig[0] &~ blocked->sig[0];
103 case 1: ready = signal->sig[0] &~ blocked->sig[0];
108 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
110 static int recalc_sigpending_tsk(struct task_struct *t)
112 if (t->signal->group_stop_count > 0 ||
113 PENDING(&t->pending, &t->blocked) ||
114 PENDING(&t->signal->shared_pending, &t->blocked)) {
115 set_tsk_thread_flag(t, TIF_SIGPENDING);
119 * We must never clear the flag in another thread, or in current
120 * when it's possible the current syscall is returning -ERESTART*.
121 * So we don't clear it here, and only callers who know they should do.
127 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
128 * This is superfluous when called on current, the wakeup is a harmless no-op.
130 void recalc_sigpending_and_wake(struct task_struct *t)
132 if (recalc_sigpending_tsk(t))
133 signal_wake_up(t, 0);
136 void recalc_sigpending(void)
138 if (unlikely(tracehook_force_sigpending()))
139 set_thread_flag(TIF_SIGPENDING);
140 else if (!recalc_sigpending_tsk(current) && !freezing(current))
141 clear_thread_flag(TIF_SIGPENDING);
145 /* Given the mask, find the first available signal that should be serviced. */
147 int next_signal(struct sigpending *pending, sigset_t *mask)
149 unsigned long i, *s, *m, x;
152 s = pending->signal.sig;
154 switch (_NSIG_WORDS) {
156 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
157 if ((x = *s &~ *m) != 0) {
158 sig = ffz(~x) + i*_NSIG_BPW + 1;
163 case 2: if ((x = s[0] &~ m[0]) != 0)
165 else if ((x = s[1] &~ m[1]) != 0)
172 case 1: if ((x = *s &~ *m) != 0)
180 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
183 struct sigqueue *q = NULL;
184 struct user_struct *user;
187 * In order to avoid problems with "switch_user()", we want to make
188 * sure that the compiler doesn't re-load "t->user"
190 user = t->cred->user;
192 atomic_inc(&user->sigpending);
193 if (override_rlimit ||
194 atomic_read(&user->sigpending) <=
195 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
196 q = kmem_cache_alloc(sigqueue_cachep, flags);
197 if (unlikely(q == NULL)) {
198 atomic_dec(&user->sigpending);
200 INIT_LIST_HEAD(&q->list);
202 q->user = get_uid(user);
207 static void __sigqueue_free(struct sigqueue *q)
209 if (q->flags & SIGQUEUE_PREALLOC)
211 atomic_dec(&q->user->sigpending);
213 kmem_cache_free(sigqueue_cachep, q);
216 void flush_sigqueue(struct sigpending *queue)
220 sigemptyset(&queue->signal);
221 while (!list_empty(&queue->list)) {
222 q = list_entry(queue->list.next, struct sigqueue , list);
223 list_del_init(&q->list);
229 * Flush all pending signals for a task.
231 void flush_signals(struct task_struct *t)
235 spin_lock_irqsave(&t->sighand->siglock, flags);
236 clear_tsk_thread_flag(t, TIF_SIGPENDING);
237 flush_sigqueue(&t->pending);
238 flush_sigqueue(&t->signal->shared_pending);
239 spin_unlock_irqrestore(&t->sighand->siglock, flags);
242 static void __flush_itimer_signals(struct sigpending *pending)
244 sigset_t signal, retain;
245 struct sigqueue *q, *n;
247 signal = pending->signal;
248 sigemptyset(&retain);
250 list_for_each_entry_safe(q, n, &pending->list, list) {
251 int sig = q->info.si_signo;
253 if (likely(q->info.si_code != SI_TIMER)) {
254 sigaddset(&retain, sig);
256 sigdelset(&signal, sig);
257 list_del_init(&q->list);
262 sigorsets(&pending->signal, &signal, &retain);
265 void flush_itimer_signals(void)
267 struct task_struct *tsk = current;
270 spin_lock_irqsave(&tsk->sighand->siglock, flags);
271 __flush_itimer_signals(&tsk->pending);
272 __flush_itimer_signals(&tsk->signal->shared_pending);
273 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
276 void ignore_signals(struct task_struct *t)
280 for (i = 0; i < _NSIG; ++i)
281 t->sighand->action[i].sa.sa_handler = SIG_IGN;
287 * Flush all handlers for a task.
291 flush_signal_handlers(struct task_struct *t, int force_default)
294 struct k_sigaction *ka = &t->sighand->action[0];
295 for (i = _NSIG ; i != 0 ; i--) {
296 if (force_default || ka->sa.sa_handler != SIG_IGN)
297 ka->sa.sa_handler = SIG_DFL;
299 sigemptyset(&ka->sa.sa_mask);
304 int unhandled_signal(struct task_struct *tsk, int sig)
306 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
307 if (is_global_init(tsk))
309 if (handler != SIG_IGN && handler != SIG_DFL)
311 return !tracehook_consider_fatal_signal(tsk, sig, handler);
315 /* Notify the system that a driver wants to block all signals for this
316 * process, and wants to be notified if any signals at all were to be
317 * sent/acted upon. If the notifier routine returns non-zero, then the
318 * signal will be acted upon after all. If the notifier routine returns 0,
319 * then then signal will be blocked. Only one block per process is
320 * allowed. priv is a pointer to private data that the notifier routine
321 * can use to determine if the signal should be blocked or not. */
324 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
328 spin_lock_irqsave(¤t->sighand->siglock, flags);
329 current->notifier_mask = mask;
330 current->notifier_data = priv;
331 current->notifier = notifier;
332 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
335 /* Notify the system that blocking has ended. */
338 unblock_all_signals(void)
342 spin_lock_irqsave(¤t->sighand->siglock, flags);
343 current->notifier = NULL;
344 current->notifier_data = NULL;
346 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
349 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
351 struct sigqueue *q, *first = NULL;
354 * Collect the siginfo appropriate to this signal. Check if
355 * there is another siginfo for the same signal.
357 list_for_each_entry(q, &list->list, list) {
358 if (q->info.si_signo == sig) {
365 sigdelset(&list->signal, sig);
369 list_del_init(&first->list);
370 copy_siginfo(info, &first->info);
371 __sigqueue_free(first);
373 /* Ok, it wasn't in the queue. This must be
374 a fast-pathed signal or we must have been
375 out of queue space. So zero out the info.
377 info->si_signo = sig;
385 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
388 int sig = next_signal(pending, mask);
391 if (current->notifier) {
392 if (sigismember(current->notifier_mask, sig)) {
393 if (!(current->notifier)(current->notifier_data)) {
394 clear_thread_flag(TIF_SIGPENDING);
400 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 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
467 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
469 * Release the siglock to ensure proper locking order
470 * of timer locks outside of siglocks. Note, we leave
471 * irqs disabled here, since the posix-timers code is
472 * about to disable them again anyway.
474 spin_unlock(&tsk->sighand->siglock);
475 do_schedule_next_timer(info);
476 spin_lock(&tsk->sighand->siglock);
482 * Tell a process that it has a new active signal..
484 * NOTE! we rely on the previous spin_lock to
485 * lock interrupts for us! We can only be called with
486 * "siglock" held, and the local interrupt must
487 * have been disabled when that got acquired!
489 * No need to set need_resched since signal event passing
490 * goes through ->blocked
492 void signal_wake_up(struct task_struct *t, int resume)
496 set_tsk_thread_flag(t, TIF_SIGPENDING);
499 * For SIGKILL, we want to wake it up in the stopped/traced/killable
500 * case. We don't check t->state here because there is a race with it
501 * executing another processor and just now entering stopped state.
502 * By using wake_up_state, we ensure the process will wake up and
503 * handle its death signal.
505 mask = TASK_INTERRUPTIBLE;
507 mask |= TASK_WAKEKILL;
508 if (!wake_up_state(t, mask))
513 * Remove signals in mask from the pending set and queue.
514 * Returns 1 if any signals were found.
516 * All callers must be holding the siglock.
518 * This version takes a sigset mask and looks at all signals,
519 * not just those in the first mask word.
521 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
523 struct sigqueue *q, *n;
526 sigandsets(&m, mask, &s->signal);
527 if (sigisemptyset(&m))
530 signandsets(&s->signal, &s->signal, mask);
531 list_for_each_entry_safe(q, n, &s->list, list) {
532 if (sigismember(mask, q->info.si_signo)) {
533 list_del_init(&q->list);
540 * Remove signals in mask from the pending set and queue.
541 * Returns 1 if any signals were found.
543 * All callers must be holding the siglock.
545 static int rm_from_queue(unsigned long mask, struct sigpending *s)
547 struct sigqueue *q, *n;
549 if (!sigtestsetmask(&s->signal, mask))
552 sigdelsetmask(&s->signal, mask);
553 list_for_each_entry_safe(q, n, &s->list, list) {
554 if (q->info.si_signo < SIGRTMIN &&
555 (mask & sigmask(q->info.si_signo))) {
556 list_del_init(&q->list);
564 * Bad permissions for sending the signal
566 static int check_kill_permission(int sig, struct siginfo *info,
567 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 */
584 euid = current_euid();
585 if ((euid ^ t->cred->suid) && (euid ^ t->cred->uid) &&
586 (uid ^ t->cred->suid) && (uid ^ t->cred->uid) &&
587 !capable(CAP_KILL)) {
590 sid = task_session(t);
592 * We don't return the error if sid == NULL. The
593 * task was unhashed, the caller must notice this.
595 if (!sid || sid == task_session(current))
602 return security_task_kill(t, info, sig, 0);
606 * Handle magic process-wide effects of stop/continue signals. Unlike
607 * the signal actions, these happen immediately at signal-generation
608 * time regardless of blocking, ignoring, or handling. This does the
609 * actual continuing for SIGCONT, but not the actual stopping for stop
610 * signals. The process stop is done as a signal action for SIG_DFL.
612 * Returns true if the signal should be actually delivered, otherwise
613 * it should be dropped.
615 static int prepare_signal(int sig, struct task_struct *p)
617 struct signal_struct *signal = p->signal;
618 struct task_struct *t;
620 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
622 * The process is in the middle of dying, nothing to do.
624 } else if (sig_kernel_stop(sig)) {
626 * This is a stop signal. Remove SIGCONT from all queues.
628 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
631 rm_from_queue(sigmask(SIGCONT), &t->pending);
632 } while_each_thread(p, t);
633 } else if (sig == SIGCONT) {
636 * Remove all stop signals from all queues,
637 * and wake all threads.
639 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
643 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
645 * If there is a handler for SIGCONT, we must make
646 * sure that no thread returns to user mode before
647 * we post the signal, in case it was the only
648 * thread eligible to run the signal handler--then
649 * it must not do anything between resuming and
650 * running the handler. With the TIF_SIGPENDING
651 * flag set, the thread will pause and acquire the
652 * siglock that we hold now and until we've queued
653 * the pending signal.
655 * Wake up the stopped thread _after_ setting
658 state = __TASK_STOPPED;
659 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
660 set_tsk_thread_flag(t, TIF_SIGPENDING);
661 state |= TASK_INTERRUPTIBLE;
663 wake_up_state(t, state);
664 } while_each_thread(p, t);
667 * Notify the parent with CLD_CONTINUED if we were stopped.
669 * If we were in the middle of a group stop, we pretend it
670 * was already finished, and then continued. Since SIGCHLD
671 * doesn't queue we report only CLD_STOPPED, as if the next
672 * CLD_CONTINUED was dropped.
675 if (signal->flags & SIGNAL_STOP_STOPPED)
676 why |= SIGNAL_CLD_CONTINUED;
677 else if (signal->group_stop_count)
678 why |= SIGNAL_CLD_STOPPED;
682 * The first thread which returns from finish_stop()
683 * will take ->siglock, notice SIGNAL_CLD_MASK, and
684 * notify its parent. See get_signal_to_deliver().
686 signal->flags = why | SIGNAL_STOP_CONTINUED;
687 signal->group_stop_count = 0;
688 signal->group_exit_code = 0;
691 * We are not stopped, but there could be a stop
692 * signal in the middle of being processed after
693 * being removed from the queue. Clear that too.
695 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
699 return !sig_ignored(p, sig);
703 * Test if P wants to take SIG. After we've checked all threads with this,
704 * it's equivalent to finding no threads not blocking SIG. Any threads not
705 * blocking SIG were ruled out because they are not running and already
706 * have pending signals. Such threads will dequeue from the shared queue
707 * as soon as they're available, so putting the signal on the shared queue
708 * will be equivalent to sending it to one such thread.
710 static inline int wants_signal(int sig, struct task_struct *p)
712 if (sigismember(&p->blocked, sig))
714 if (p->flags & PF_EXITING)
718 if (task_is_stopped_or_traced(p))
720 return task_curr(p) || !signal_pending(p);
723 static void complete_signal(int sig, struct task_struct *p, int group)
725 struct signal_struct *signal = p->signal;
726 struct task_struct *t;
729 * Now find a thread we can wake up to take the signal off the queue.
731 * If the main thread wants the signal, it gets first crack.
732 * Probably the least surprising to the average bear.
734 if (wants_signal(sig, p))
736 else if (!group || thread_group_empty(p))
738 * There is just one thread and it does not need to be woken.
739 * It will dequeue unblocked signals before it runs again.
744 * Otherwise try to find a suitable thread.
746 t = signal->curr_target;
747 while (!wants_signal(sig, t)) {
749 if (t == signal->curr_target)
751 * No thread needs to be woken.
752 * Any eligible threads will see
753 * the signal in the queue soon.
757 signal->curr_target = t;
761 * Found a killable thread. If the signal will be fatal,
762 * then start taking the whole group down immediately.
764 if (sig_fatal(p, sig) &&
765 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
766 !sigismember(&t->real_blocked, sig) &&
768 !tracehook_consider_fatal_signal(t, sig, SIG_DFL))) {
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 trace_sched_signal_send(sig, t);
812 assert_spin_locked(&t->sighand->siglock);
813 if (!prepare_signal(sig, t))
816 pending = group ? &t->signal->shared_pending : &t->pending;
818 * Short-circuit ignored signals and support queuing
819 * exactly one non-rt signal, so that we can get more
820 * detailed information about the cause of the signal.
822 if (legacy_queue(pending, sig))
825 * fast-pathed signals for kernel-internal things like SIGSTOP
828 if (info == SEND_SIG_FORCED)
831 /* Real-time signals must be queued if sent by sigqueue, or
832 some other real-time mechanism. It is implementation
833 defined whether kill() does so. We attempt to do so, on
834 the principle of least surprise, but since kill is not
835 allowed to fail with EAGAIN when low on memory we just
836 make sure at least one signal gets delivered and don't
837 pass on the info struct. */
839 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
840 (is_si_special(info) ||
841 info->si_code >= 0)));
843 list_add_tail(&q->list, &pending->list);
844 switch ((unsigned long) info) {
845 case (unsigned long) SEND_SIG_NOINFO:
846 q->info.si_signo = sig;
847 q->info.si_errno = 0;
848 q->info.si_code = SI_USER;
849 q->info.si_pid = task_pid_vnr(current);
850 q->info.si_uid = current_uid();
852 case (unsigned long) SEND_SIG_PRIV:
853 q->info.si_signo = sig;
854 q->info.si_errno = 0;
855 q->info.si_code = SI_KERNEL;
860 copy_siginfo(&q->info, info);
863 } else if (!is_si_special(info)) {
864 if (sig >= SIGRTMIN && info->si_code != SI_USER)
866 * Queue overflow, abort. We may abort if the signal was rt
867 * and sent by user using something other than kill().
873 signalfd_notify(t, sig);
874 sigaddset(&pending->signal, sig);
875 complete_signal(sig, t, group);
879 int print_fatal_signals;
881 static void print_fatal_signal(struct pt_regs *regs, int signr)
883 printk("%s/%d: potentially unexpected fatal signal %d.\n",
884 current->comm, task_pid_nr(current), signr);
886 #if defined(__i386__) && !defined(__arch_um__)
887 printk("code at %08lx: ", regs->ip);
890 for (i = 0; i < 16; i++) {
893 __get_user(insn, (unsigned char *)(regs->ip + i));
894 printk("%02x ", insn);
902 static int __init setup_print_fatal_signals(char *str)
904 get_option (&str, &print_fatal_signals);
909 __setup("print-fatal-signals=", setup_print_fatal_signals);
912 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
914 return send_signal(sig, info, p, 1);
918 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
920 return send_signal(sig, info, t, 0);
924 * Force a signal that the process can't ignore: if necessary
925 * we unblock the signal and change any SIG_IGN to SIG_DFL.
927 * Note: If we unblock the signal, we always reset it to SIG_DFL,
928 * since we do not want to have a signal handler that was blocked
929 * be invoked when user space had explicitly blocked it.
931 * We don't want to have recursive SIGSEGV's etc, for example,
932 * that is why we also clear SIGNAL_UNKILLABLE.
935 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
937 unsigned long int flags;
938 int ret, blocked, ignored;
939 struct k_sigaction *action;
941 spin_lock_irqsave(&t->sighand->siglock, flags);
942 action = &t->sighand->action[sig-1];
943 ignored = action->sa.sa_handler == SIG_IGN;
944 blocked = sigismember(&t->blocked, sig);
945 if (blocked || ignored) {
946 action->sa.sa_handler = SIG_DFL;
948 sigdelset(&t->blocked, sig);
949 recalc_sigpending_and_wake(t);
952 if (action->sa.sa_handler == SIG_DFL)
953 t->signal->flags &= ~SIGNAL_UNKILLABLE;
954 ret = specific_send_sig_info(sig, info, t);
955 spin_unlock_irqrestore(&t->sighand->siglock, flags);
961 force_sig_specific(int sig, struct task_struct *t)
963 force_sig_info(sig, SEND_SIG_FORCED, t);
967 * Nuke all other threads in the group.
969 void zap_other_threads(struct task_struct *p)
971 struct task_struct *t;
973 p->signal->group_stop_count = 0;
975 for (t = next_thread(p); t != p; t = next_thread(t)) {
977 * Don't bother with already dead threads
982 /* SIGKILL will be handled before any pending SIGSTOP */
983 sigaddset(&t->pending.signal, SIGKILL);
984 signal_wake_up(t, 1);
988 int __fatal_signal_pending(struct task_struct *tsk)
990 return sigismember(&tsk->pending.signal, SIGKILL);
992 EXPORT_SYMBOL(__fatal_signal_pending);
994 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
996 struct sighand_struct *sighand;
1000 sighand = rcu_dereference(tsk->sighand);
1001 if (unlikely(sighand == NULL))
1004 spin_lock_irqsave(&sighand->siglock, *flags);
1005 if (likely(sighand == tsk->sighand))
1007 spin_unlock_irqrestore(&sighand->siglock, *flags);
1014 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1016 unsigned long flags;
1019 ret = check_kill_permission(sig, info, p);
1023 if (lock_task_sighand(p, &flags)) {
1024 ret = __group_send_sig_info(sig, info, p);
1025 unlock_task_sighand(p, &flags);
1033 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1034 * control characters do (^C, ^Z etc)
1037 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1039 struct task_struct *p = NULL;
1040 int retval, success;
1044 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1045 int err = group_send_sig_info(sig, info, p);
1048 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1049 return success ? 0 : retval;
1052 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1055 struct task_struct *p;
1059 p = pid_task(pid, PIDTYPE_PID);
1061 error = group_send_sig_info(sig, info, p);
1062 if (unlikely(error == -ESRCH))
1064 * The task was unhashed in between, try again.
1065 * If it is dead, pid_task() will return NULL,
1066 * if we race with de_thread() it will find the
1077 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1081 error = kill_pid_info(sig, info, find_vpid(pid));
1086 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1087 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1088 uid_t uid, uid_t euid, u32 secid)
1091 struct task_struct *p;
1093 if (!valid_signal(sig))
1096 read_lock(&tasklist_lock);
1097 p = pid_task(pid, PIDTYPE_PID);
1102 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1103 && (euid != p->cred->suid) && (euid != p->cred->uid)
1104 && (uid != p->cred->suid) && (uid != p->cred->uid)) {
1108 ret = security_task_kill(p, info, sig, secid);
1111 if (sig && p->sighand) {
1112 unsigned long flags;
1113 spin_lock_irqsave(&p->sighand->siglock, flags);
1114 ret = __group_send_sig_info(sig, info, p);
1115 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1118 read_unlock(&tasklist_lock);
1121 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1124 * kill_something_info() interprets pid in interesting ways just like kill(2).
1126 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1127 * is probably wrong. Should make it like BSD or SYSV.
1130 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1136 ret = kill_pid_info(sig, info, find_vpid(pid));
1141 read_lock(&tasklist_lock);
1143 ret = __kill_pgrp_info(sig, info,
1144 pid ? find_vpid(-pid) : task_pgrp(current));
1146 int retval = 0, count = 0;
1147 struct task_struct * p;
1149 for_each_process(p) {
1150 if (task_pid_vnr(p) > 1 &&
1151 !same_thread_group(p, current)) {
1152 int err = group_send_sig_info(sig, info, p);
1158 ret = count ? retval : -ESRCH;
1160 read_unlock(&tasklist_lock);
1166 * These are for backward compatibility with the rest of the kernel source.
1170 * The caller must ensure the task can't exit.
1173 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1176 unsigned long flags;
1179 * Make sure legacy kernel users don't send in bad values
1180 * (normal paths check this in check_kill_permission).
1182 if (!valid_signal(sig))
1185 spin_lock_irqsave(&p->sighand->siglock, flags);
1186 ret = specific_send_sig_info(sig, info, p);
1187 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1191 #define __si_special(priv) \
1192 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1195 send_sig(int sig, struct task_struct *p, int priv)
1197 return send_sig_info(sig, __si_special(priv), p);
1201 force_sig(int sig, struct task_struct *p)
1203 force_sig_info(sig, SEND_SIG_PRIV, p);
1207 * When things go south during signal handling, we
1208 * will force a SIGSEGV. And if the signal that caused
1209 * the problem was already a SIGSEGV, we'll want to
1210 * make sure we don't even try to deliver the signal..
1213 force_sigsegv(int sig, struct task_struct *p)
1215 if (sig == SIGSEGV) {
1216 unsigned long flags;
1217 spin_lock_irqsave(&p->sighand->siglock, flags);
1218 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1219 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1221 force_sig(SIGSEGV, p);
1225 int kill_pgrp(struct pid *pid, int sig, int priv)
1229 read_lock(&tasklist_lock);
1230 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1231 read_unlock(&tasklist_lock);
1235 EXPORT_SYMBOL(kill_pgrp);
1237 int kill_pid(struct pid *pid, int sig, int priv)
1239 return kill_pid_info(sig, __si_special(priv), pid);
1241 EXPORT_SYMBOL(kill_pid);
1244 * These functions support sending signals using preallocated sigqueue
1245 * structures. This is needed "because realtime applications cannot
1246 * afford to lose notifications of asynchronous events, like timer
1247 * expirations or I/O completions". In the case of Posix Timers
1248 * we allocate the sigqueue structure from the timer_create. If this
1249 * allocation fails we are able to report the failure to the application
1250 * with an EAGAIN error.
1253 struct sigqueue *sigqueue_alloc(void)
1257 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1258 q->flags |= SIGQUEUE_PREALLOC;
1262 void sigqueue_free(struct sigqueue *q)
1264 unsigned long flags;
1265 spinlock_t *lock = ¤t->sighand->siglock;
1267 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1269 * We must hold ->siglock while testing q->list
1270 * to serialize with collect_signal() or with
1271 * __exit_signal()->flush_sigqueue().
1273 spin_lock_irqsave(lock, flags);
1274 q->flags &= ~SIGQUEUE_PREALLOC;
1276 * If it is queued it will be freed when dequeued,
1277 * like the "regular" sigqueue.
1279 if (!list_empty(&q->list))
1281 spin_unlock_irqrestore(lock, flags);
1287 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1289 int sig = q->info.si_signo;
1290 struct sigpending *pending;
1291 unsigned long flags;
1294 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1297 if (!likely(lock_task_sighand(t, &flags)))
1300 ret = 1; /* the signal is ignored */
1301 if (!prepare_signal(sig, t))
1305 if (unlikely(!list_empty(&q->list))) {
1307 * If an SI_TIMER entry is already queue just increment
1308 * the overrun count.
1310 BUG_ON(q->info.si_code != SI_TIMER);
1311 q->info.si_overrun++;
1314 q->info.si_overrun = 0;
1316 signalfd_notify(t, sig);
1317 pending = group ? &t->signal->shared_pending : &t->pending;
1318 list_add_tail(&q->list, &pending->list);
1319 sigaddset(&pending->signal, sig);
1320 complete_signal(sig, t, group);
1322 unlock_task_sighand(t, &flags);
1328 * Wake up any threads in the parent blocked in wait* syscalls.
1330 static inline void __wake_up_parent(struct task_struct *p,
1331 struct task_struct *parent)
1333 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1337 * Let a parent know about the death of a child.
1338 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1340 * Returns -1 if our parent ignored us and so we've switched to
1341 * self-reaping, or else @sig.
1343 int do_notify_parent(struct task_struct *tsk, int sig)
1345 struct siginfo info;
1346 unsigned long flags;
1347 struct sighand_struct *psig;
1348 struct task_cputime cputime;
1353 /* do_notify_parent_cldstop should have been called instead. */
1354 BUG_ON(task_is_stopped_or_traced(tsk));
1356 BUG_ON(!tsk->ptrace &&
1357 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1359 info.si_signo = sig;
1362 * we are under tasklist_lock here so our parent is tied to
1363 * us and cannot exit and release its namespace.
1365 * the only it can is to switch its nsproxy with sys_unshare,
1366 * bu uncharing pid namespaces is not allowed, so we'll always
1367 * see relevant namespace
1369 * write_lock() currently calls preempt_disable() which is the
1370 * same as rcu_read_lock(), but according to Oleg, this is not
1371 * correct to rely on this
1374 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1377 info.si_uid = tsk->cred->uid;
1379 thread_group_cputime(tsk, &cputime);
1380 info.si_utime = cputime_to_jiffies(cputime.utime);
1381 info.si_stime = cputime_to_jiffies(cputime.stime);
1383 info.si_status = tsk->exit_code & 0x7f;
1384 if (tsk->exit_code & 0x80)
1385 info.si_code = CLD_DUMPED;
1386 else if (tsk->exit_code & 0x7f)
1387 info.si_code = CLD_KILLED;
1389 info.si_code = CLD_EXITED;
1390 info.si_status = tsk->exit_code >> 8;
1393 psig = tsk->parent->sighand;
1394 spin_lock_irqsave(&psig->siglock, flags);
1395 if (!tsk->ptrace && sig == SIGCHLD &&
1396 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1397 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1399 * We are exiting and our parent doesn't care. POSIX.1
1400 * defines special semantics for setting SIGCHLD to SIG_IGN
1401 * or setting the SA_NOCLDWAIT flag: we should be reaped
1402 * automatically and not left for our parent's wait4 call.
1403 * Rather than having the parent do it as a magic kind of
1404 * signal handler, we just set this to tell do_exit that we
1405 * can be cleaned up without becoming a zombie. Note that
1406 * we still call __wake_up_parent in this case, because a
1407 * blocked sys_wait4 might now return -ECHILD.
1409 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1410 * is implementation-defined: we do (if you don't want
1411 * it, just use SIG_IGN instead).
1413 ret = tsk->exit_signal = -1;
1414 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1417 if (valid_signal(sig) && sig > 0)
1418 __group_send_sig_info(sig, &info, tsk->parent);
1419 __wake_up_parent(tsk, tsk->parent);
1420 spin_unlock_irqrestore(&psig->siglock, flags);
1425 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1427 struct siginfo info;
1428 unsigned long flags;
1429 struct task_struct *parent;
1430 struct sighand_struct *sighand;
1432 if (tsk->ptrace & PT_PTRACED)
1433 parent = tsk->parent;
1435 tsk = tsk->group_leader;
1436 parent = tsk->real_parent;
1439 info.si_signo = SIGCHLD;
1442 * see comment in do_notify_parent() abot the following 3 lines
1445 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1448 info.si_uid = tsk->cred->uid;
1450 info.si_utime = cputime_to_clock_t(tsk->utime);
1451 info.si_stime = cputime_to_clock_t(tsk->stime);
1456 info.si_status = SIGCONT;
1459 info.si_status = tsk->signal->group_exit_code & 0x7f;
1462 info.si_status = tsk->exit_code & 0x7f;
1468 sighand = parent->sighand;
1469 spin_lock_irqsave(&sighand->siglock, flags);
1470 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1471 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1472 __group_send_sig_info(SIGCHLD, &info, parent);
1474 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1476 __wake_up_parent(tsk, parent);
1477 spin_unlock_irqrestore(&sighand->siglock, flags);
1480 static inline int may_ptrace_stop(void)
1482 if (!likely(current->ptrace & PT_PTRACED))
1485 * Are we in the middle of do_coredump?
1486 * If so and our tracer is also part of the coredump stopping
1487 * is a deadlock situation, and pointless because our tracer
1488 * is dead so don't allow us to stop.
1489 * If SIGKILL was already sent before the caller unlocked
1490 * ->siglock we must see ->core_state != NULL. Otherwise it
1491 * is safe to enter schedule().
1493 if (unlikely(current->mm->core_state) &&
1494 unlikely(current->mm == current->parent->mm))
1501 * Return nonzero if there is a SIGKILL that should be waking us up.
1502 * Called with the siglock held.
1504 static int sigkill_pending(struct task_struct *tsk)
1506 return sigismember(&tsk->pending.signal, SIGKILL) ||
1507 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1511 * This must be called with current->sighand->siglock held.
1513 * This should be the path for all ptrace stops.
1514 * We always set current->last_siginfo while stopped here.
1515 * That makes it a way to test a stopped process for
1516 * being ptrace-stopped vs being job-control-stopped.
1518 * If we actually decide not to stop at all because the tracer
1519 * is gone, we keep current->exit_code unless clear_code.
1521 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1523 if (arch_ptrace_stop_needed(exit_code, info)) {
1525 * The arch code has something special to do before a
1526 * ptrace stop. This is allowed to block, e.g. for faults
1527 * on user stack pages. We can't keep the siglock while
1528 * calling arch_ptrace_stop, so we must release it now.
1529 * To preserve proper semantics, we must do this before
1530 * any signal bookkeeping like checking group_stop_count.
1531 * Meanwhile, a SIGKILL could come in before we retake the
1532 * siglock. That must prevent us from sleeping in TASK_TRACED.
1533 * So after regaining the lock, we must check for SIGKILL.
1535 spin_unlock_irq(¤t->sighand->siglock);
1536 arch_ptrace_stop(exit_code, info);
1537 spin_lock_irq(¤t->sighand->siglock);
1538 if (sigkill_pending(current))
1543 * If there is a group stop in progress,
1544 * we must participate in the bookkeeping.
1546 if (current->signal->group_stop_count > 0)
1547 --current->signal->group_stop_count;
1549 current->last_siginfo = info;
1550 current->exit_code = exit_code;
1552 /* Let the debugger run. */
1553 __set_current_state(TASK_TRACED);
1554 spin_unlock_irq(¤t->sighand->siglock);
1555 read_lock(&tasklist_lock);
1556 if (may_ptrace_stop()) {
1557 do_notify_parent_cldstop(current, CLD_TRAPPED);
1558 read_unlock(&tasklist_lock);
1562 * By the time we got the lock, our tracer went away.
1563 * Don't drop the lock yet, another tracer may come.
1565 __set_current_state(TASK_RUNNING);
1567 current->exit_code = 0;
1568 read_unlock(&tasklist_lock);
1572 * While in TASK_TRACED, we were considered "frozen enough".
1573 * Now that we woke up, it's crucial if we're supposed to be
1574 * frozen that we freeze now before running anything substantial.
1579 * We are back. Now reacquire the siglock before touching
1580 * last_siginfo, so that we are sure to have synchronized with
1581 * any signal-sending on another CPU that wants to examine it.
1583 spin_lock_irq(¤t->sighand->siglock);
1584 current->last_siginfo = NULL;
1587 * Queued signals ignored us while we were stopped for tracing.
1588 * So check for any that we should take before resuming user mode.
1589 * This sets TIF_SIGPENDING, but never clears it.
1591 recalc_sigpending_tsk(current);
1594 void ptrace_notify(int exit_code)
1598 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1600 memset(&info, 0, sizeof info);
1601 info.si_signo = SIGTRAP;
1602 info.si_code = exit_code;
1603 info.si_pid = task_pid_vnr(current);
1604 info.si_uid = current_uid();
1606 /* Let the debugger run. */
1607 spin_lock_irq(¤t->sighand->siglock);
1608 ptrace_stop(exit_code, 1, &info);
1609 spin_unlock_irq(¤t->sighand->siglock);
1613 finish_stop(int stop_count)
1616 * If there are no other threads in the group, or if there is
1617 * a group stop in progress and we are the last to stop,
1618 * report to the parent. When ptraced, every thread reports itself.
1620 if (tracehook_notify_jctl(stop_count == 0, CLD_STOPPED)) {
1621 read_lock(&tasklist_lock);
1622 do_notify_parent_cldstop(current, CLD_STOPPED);
1623 read_unlock(&tasklist_lock);
1628 } while (try_to_freeze());
1630 * Now we don't run again until continued.
1632 current->exit_code = 0;
1636 * This performs the stopping for SIGSTOP and other stop signals.
1637 * We have to stop all threads in the thread group.
1638 * Returns nonzero if we've actually stopped and released the siglock.
1639 * Returns zero if we didn't stop and still hold the siglock.
1641 static int do_signal_stop(int signr)
1643 struct signal_struct *sig = current->signal;
1646 if (sig->group_stop_count > 0) {
1648 * There is a group stop in progress. We don't need to
1649 * start another one.
1651 stop_count = --sig->group_stop_count;
1653 struct task_struct *t;
1655 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1656 unlikely(signal_group_exit(sig)))
1659 * There is no group stop already in progress.
1660 * We must initiate one now.
1662 sig->group_exit_code = signr;
1665 for (t = next_thread(current); t != current; t = next_thread(t))
1667 * Setting state to TASK_STOPPED for a group
1668 * stop is always done with the siglock held,
1669 * so this check has no races.
1671 if (!(t->flags & PF_EXITING) &&
1672 !task_is_stopped_or_traced(t)) {
1674 signal_wake_up(t, 0);
1676 sig->group_stop_count = stop_count;
1679 if (stop_count == 0)
1680 sig->flags = SIGNAL_STOP_STOPPED;
1681 current->exit_code = sig->group_exit_code;
1682 __set_current_state(TASK_STOPPED);
1684 spin_unlock_irq(¤t->sighand->siglock);
1685 finish_stop(stop_count);
1689 static int ptrace_signal(int signr, siginfo_t *info,
1690 struct pt_regs *regs, void *cookie)
1692 if (!(current->ptrace & PT_PTRACED))
1695 ptrace_signal_deliver(regs, cookie);
1697 /* Let the debugger run. */
1698 ptrace_stop(signr, 0, info);
1700 /* We're back. Did the debugger cancel the sig? */
1701 signr = current->exit_code;
1705 current->exit_code = 0;
1707 /* Update the siginfo structure if the signal has
1708 changed. If the debugger wanted something
1709 specific in the siginfo structure then it should
1710 have updated *info via PTRACE_SETSIGINFO. */
1711 if (signr != info->si_signo) {
1712 info->si_signo = signr;
1714 info->si_code = SI_USER;
1715 info->si_pid = task_pid_vnr(current->parent);
1716 info->si_uid = current->parent->cred->uid;
1719 /* If the (new) signal is now blocked, requeue it. */
1720 if (sigismember(¤t->blocked, signr)) {
1721 specific_send_sig_info(signr, info, current);
1728 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1729 struct pt_regs *regs, void *cookie)
1731 struct sighand_struct *sighand = current->sighand;
1732 struct signal_struct *signal = current->signal;
1737 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1738 * While in TASK_STOPPED, we were considered "frozen enough".
1739 * Now that we woke up, it's crucial if we're supposed to be
1740 * frozen that we freeze now before running anything substantial.
1744 spin_lock_irq(&sighand->siglock);
1746 * Every stopped thread goes here after wakeup. Check to see if
1747 * we should notify the parent, prepare_signal(SIGCONT) encodes
1748 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1750 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1751 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1752 ? CLD_CONTINUED : CLD_STOPPED;
1753 signal->flags &= ~SIGNAL_CLD_MASK;
1754 spin_unlock_irq(&sighand->siglock);
1756 if (unlikely(!tracehook_notify_jctl(1, why)))
1759 read_lock(&tasklist_lock);
1760 do_notify_parent_cldstop(current->group_leader, why);
1761 read_unlock(&tasklist_lock);
1766 struct k_sigaction *ka;
1768 if (unlikely(signal->group_stop_count > 0) &&
1773 * Tracing can induce an artifical signal and choose sigaction.
1774 * The return value in @signr determines the default action,
1775 * but @info->si_signo is the signal number we will report.
1777 signr = tracehook_get_signal(current, regs, info, return_ka);
1778 if (unlikely(signr < 0))
1780 if (unlikely(signr != 0))
1783 signr = dequeue_signal(current, ¤t->blocked,
1787 break; /* will return 0 */
1789 if (signr != SIGKILL) {
1790 signr = ptrace_signal(signr, info,
1796 ka = &sighand->action[signr-1];
1799 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1801 if (ka->sa.sa_handler != SIG_DFL) {
1802 /* Run the handler. */
1805 if (ka->sa.sa_flags & SA_ONESHOT)
1806 ka->sa.sa_handler = SIG_DFL;
1808 break; /* will return non-zero "signr" value */
1812 * Now we are doing the default action for this signal.
1814 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1818 * Global init gets no signals it doesn't want.
1820 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
1821 !signal_group_exit(signal))
1824 if (sig_kernel_stop(signr)) {
1826 * The default action is to stop all threads in
1827 * the thread group. The job control signals
1828 * do nothing in an orphaned pgrp, but SIGSTOP
1829 * always works. Note that siglock needs to be
1830 * dropped during the call to is_orphaned_pgrp()
1831 * because of lock ordering with tasklist_lock.
1832 * This allows an intervening SIGCONT to be posted.
1833 * We need to check for that and bail out if necessary.
1835 if (signr != SIGSTOP) {
1836 spin_unlock_irq(&sighand->siglock);
1838 /* signals can be posted during this window */
1840 if (is_current_pgrp_orphaned())
1843 spin_lock_irq(&sighand->siglock);
1846 if (likely(do_signal_stop(info->si_signo))) {
1847 /* It released the siglock. */
1852 * We didn't actually stop, due to a race
1853 * with SIGCONT or something like that.
1858 spin_unlock_irq(&sighand->siglock);
1861 * Anything else is fatal, maybe with a core dump.
1863 current->flags |= PF_SIGNALED;
1865 if (sig_kernel_coredump(signr)) {
1866 if (print_fatal_signals)
1867 print_fatal_signal(regs, info->si_signo);
1869 * If it was able to dump core, this kills all
1870 * other threads in the group and synchronizes with
1871 * their demise. If we lost the race with another
1872 * thread getting here, it set group_exit_code
1873 * first and our do_group_exit call below will use
1874 * that value and ignore the one we pass it.
1876 do_coredump(info->si_signo, info->si_signo, regs);
1880 * Death signals, no core dump.
1882 do_group_exit(info->si_signo);
1885 spin_unlock_irq(&sighand->siglock);
1889 void exit_signals(struct task_struct *tsk)
1892 struct task_struct *t;
1894 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1895 tsk->flags |= PF_EXITING;
1899 spin_lock_irq(&tsk->sighand->siglock);
1901 * From now this task is not visible for group-wide signals,
1902 * see wants_signal(), do_signal_stop().
1904 tsk->flags |= PF_EXITING;
1905 if (!signal_pending(tsk))
1908 /* It could be that __group_complete_signal() choose us to
1909 * notify about group-wide signal. Another thread should be
1910 * woken now to take the signal since we will not.
1912 for (t = tsk; (t = next_thread(t)) != tsk; )
1913 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1914 recalc_sigpending_and_wake(t);
1916 if (unlikely(tsk->signal->group_stop_count) &&
1917 !--tsk->signal->group_stop_count) {
1918 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1922 spin_unlock_irq(&tsk->sighand->siglock);
1924 if (unlikely(group_stop) && tracehook_notify_jctl(1, CLD_STOPPED)) {
1925 read_lock(&tasklist_lock);
1926 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1927 read_unlock(&tasklist_lock);
1931 EXPORT_SYMBOL(recalc_sigpending);
1932 EXPORT_SYMBOL_GPL(dequeue_signal);
1933 EXPORT_SYMBOL(flush_signals);
1934 EXPORT_SYMBOL(force_sig);
1935 EXPORT_SYMBOL(send_sig);
1936 EXPORT_SYMBOL(send_sig_info);
1937 EXPORT_SYMBOL(sigprocmask);
1938 EXPORT_SYMBOL(block_all_signals);
1939 EXPORT_SYMBOL(unblock_all_signals);
1943 * System call entry points.
1946 asmlinkage long sys_restart_syscall(void)
1948 struct restart_block *restart = ¤t_thread_info()->restart_block;
1949 return restart->fn(restart);
1952 long do_no_restart_syscall(struct restart_block *param)
1958 * We don't need to get the kernel lock - this is all local to this
1959 * particular thread.. (and that's good, because this is _heavily_
1960 * used by various programs)
1964 * This is also useful for kernel threads that want to temporarily
1965 * (or permanently) block certain signals.
1967 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1968 * interface happily blocks "unblockable" signals like SIGKILL
1971 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1975 spin_lock_irq(¤t->sighand->siglock);
1977 *oldset = current->blocked;
1982 sigorsets(¤t->blocked, ¤t->blocked, set);
1985 signandsets(¤t->blocked, ¤t->blocked, set);
1988 current->blocked = *set;
1993 recalc_sigpending();
1994 spin_unlock_irq(¤t->sighand->siglock);
2000 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2002 int error = -EINVAL;
2003 sigset_t old_set, new_set;
2005 /* XXX: Don't preclude handling different sized sigset_t's. */
2006 if (sigsetsize != sizeof(sigset_t))
2011 if (copy_from_user(&new_set, set, sizeof(*set)))
2013 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2015 error = sigprocmask(how, &new_set, &old_set);
2021 spin_lock_irq(¤t->sighand->siglock);
2022 old_set = current->blocked;
2023 spin_unlock_irq(¤t->sighand->siglock);
2027 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2035 long do_sigpending(void __user *set, unsigned long sigsetsize)
2037 long error = -EINVAL;
2040 if (sigsetsize > sizeof(sigset_t))
2043 spin_lock_irq(¤t->sighand->siglock);
2044 sigorsets(&pending, ¤t->pending.signal,
2045 ¤t->signal->shared_pending.signal);
2046 spin_unlock_irq(¤t->sighand->siglock);
2048 /* Outside the lock because only this thread touches it. */
2049 sigandsets(&pending, ¤t->blocked, &pending);
2052 if (!copy_to_user(set, &pending, sigsetsize))
2060 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2062 return do_sigpending(set, sigsetsize);
2065 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2067 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2071 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2073 if (from->si_code < 0)
2074 return __copy_to_user(to, from, sizeof(siginfo_t))
2077 * If you change siginfo_t structure, please be sure
2078 * this code is fixed accordingly.
2079 * Please remember to update the signalfd_copyinfo() function
2080 * inside fs/signalfd.c too, in case siginfo_t changes.
2081 * It should never copy any pad contained in the structure
2082 * to avoid security leaks, but must copy the generic
2083 * 3 ints plus the relevant union member.
2085 err = __put_user(from->si_signo, &to->si_signo);
2086 err |= __put_user(from->si_errno, &to->si_errno);
2087 err |= __put_user((short)from->si_code, &to->si_code);
2088 switch (from->si_code & __SI_MASK) {
2090 err |= __put_user(from->si_pid, &to->si_pid);
2091 err |= __put_user(from->si_uid, &to->si_uid);
2094 err |= __put_user(from->si_tid, &to->si_tid);
2095 err |= __put_user(from->si_overrun, &to->si_overrun);
2096 err |= __put_user(from->si_ptr, &to->si_ptr);
2099 err |= __put_user(from->si_band, &to->si_band);
2100 err |= __put_user(from->si_fd, &to->si_fd);
2103 err |= __put_user(from->si_addr, &to->si_addr);
2104 #ifdef __ARCH_SI_TRAPNO
2105 err |= __put_user(from->si_trapno, &to->si_trapno);
2109 err |= __put_user(from->si_pid, &to->si_pid);
2110 err |= __put_user(from->si_uid, &to->si_uid);
2111 err |= __put_user(from->si_status, &to->si_status);
2112 err |= __put_user(from->si_utime, &to->si_utime);
2113 err |= __put_user(from->si_stime, &to->si_stime);
2115 case __SI_RT: /* This is not generated by the kernel as of now. */
2116 case __SI_MESGQ: /* But this is */
2117 err |= __put_user(from->si_pid, &to->si_pid);
2118 err |= __put_user(from->si_uid, &to->si_uid);
2119 err |= __put_user(from->si_ptr, &to->si_ptr);
2121 default: /* this is just in case for now ... */
2122 err |= __put_user(from->si_pid, &to->si_pid);
2123 err |= __put_user(from->si_uid, &to->si_uid);
2132 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2133 siginfo_t __user *uinfo,
2134 const struct timespec __user *uts,
2143 /* XXX: Don't preclude handling different sized sigset_t's. */
2144 if (sigsetsize != sizeof(sigset_t))
2147 if (copy_from_user(&these, uthese, sizeof(these)))
2151 * Invert the set of allowed signals to get those we
2154 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2158 if (copy_from_user(&ts, uts, sizeof(ts)))
2160 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2165 spin_lock_irq(¤t->sighand->siglock);
2166 sig = dequeue_signal(current, &these, &info);
2168 timeout = MAX_SCHEDULE_TIMEOUT;
2170 timeout = (timespec_to_jiffies(&ts)
2171 + (ts.tv_sec || ts.tv_nsec));
2174 /* None ready -- temporarily unblock those we're
2175 * interested while we are sleeping in so that we'll
2176 * be awakened when they arrive. */
2177 current->real_blocked = current->blocked;
2178 sigandsets(¤t->blocked, ¤t->blocked, &these);
2179 recalc_sigpending();
2180 spin_unlock_irq(¤t->sighand->siglock);
2182 timeout = schedule_timeout_interruptible(timeout);
2184 spin_lock_irq(¤t->sighand->siglock);
2185 sig = dequeue_signal(current, &these, &info);
2186 current->blocked = current->real_blocked;
2187 siginitset(¤t->real_blocked, 0);
2188 recalc_sigpending();
2191 spin_unlock_irq(¤t->sighand->siglock);
2196 if (copy_siginfo_to_user(uinfo, &info))
2209 sys_kill(pid_t pid, int sig)
2211 struct siginfo info;
2213 info.si_signo = sig;
2215 info.si_code = SI_USER;
2216 info.si_pid = task_tgid_vnr(current);
2217 info.si_uid = current_uid();
2219 return kill_something_info(sig, &info, pid);
2222 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2225 struct siginfo info;
2226 struct task_struct *p;
2227 unsigned long flags;
2230 info.si_signo = sig;
2232 info.si_code = SI_TKILL;
2233 info.si_pid = task_tgid_vnr(current);
2234 info.si_uid = current_uid();
2237 p = find_task_by_vpid(pid);
2238 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2239 error = check_kill_permission(sig, &info, p);
2241 * The null signal is a permissions and process existence
2242 * probe. No signal is actually delivered.
2244 * If lock_task_sighand() fails we pretend the task dies
2245 * after receiving the signal. The window is tiny, and the
2246 * signal is private anyway.
2248 if (!error && sig && lock_task_sighand(p, &flags)) {
2249 error = specific_send_sig_info(sig, &info, p);
2250 unlock_task_sighand(p, &flags);
2259 * sys_tgkill - send signal to one specific thread
2260 * @tgid: the thread group ID of the thread
2261 * @pid: the PID of the thread
2262 * @sig: signal to be sent
2264 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2265 * exists but it's not belonging to the target process anymore. This
2266 * method solves the problem of threads exiting and PIDs getting reused.
2268 asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig)
2270 /* This is only valid for single tasks */
2271 if (pid <= 0 || tgid <= 0)
2274 return do_tkill(tgid, pid, sig);
2278 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2281 sys_tkill(pid_t pid, int sig)
2283 /* This is only valid for single tasks */
2287 return do_tkill(0, pid, sig);
2291 sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo)
2295 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2298 /* Not even root can pretend to send signals from the kernel.
2299 Nor can they impersonate a kill(), which adds source info. */
2300 if (info.si_code >= 0)
2302 info.si_signo = sig;
2304 /* POSIX.1b doesn't mention process groups. */
2305 return kill_proc_info(sig, &info, pid);
2308 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2310 struct task_struct *t = current;
2311 struct k_sigaction *k;
2314 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2317 k = &t->sighand->action[sig-1];
2319 spin_lock_irq(¤t->sighand->siglock);
2324 sigdelsetmask(&act->sa.sa_mask,
2325 sigmask(SIGKILL) | sigmask(SIGSTOP));
2329 * "Setting a signal action to SIG_IGN for a signal that is
2330 * pending shall cause the pending signal to be discarded,
2331 * whether or not it is blocked."
2333 * "Setting a signal action to SIG_DFL for a signal that is
2334 * pending and whose default action is to ignore the signal
2335 * (for example, SIGCHLD), shall cause the pending signal to
2336 * be discarded, whether or not it is blocked"
2338 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2340 sigaddset(&mask, sig);
2341 rm_from_queue_full(&mask, &t->signal->shared_pending);
2343 rm_from_queue_full(&mask, &t->pending);
2345 } while (t != current);
2349 spin_unlock_irq(¤t->sighand->siglock);
2354 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2360 oss.ss_sp = (void __user *) current->sas_ss_sp;
2361 oss.ss_size = current->sas_ss_size;
2362 oss.ss_flags = sas_ss_flags(sp);
2371 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2372 || __get_user(ss_sp, &uss->ss_sp)
2373 || __get_user(ss_flags, &uss->ss_flags)
2374 || __get_user(ss_size, &uss->ss_size))
2378 if (on_sig_stack(sp))
2384 * Note - this code used to test ss_flags incorrectly
2385 * old code may have been written using ss_flags==0
2386 * to mean ss_flags==SS_ONSTACK (as this was the only
2387 * way that worked) - this fix preserves that older
2390 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2393 if (ss_flags == SS_DISABLE) {
2398 if (ss_size < MINSIGSTKSZ)
2402 current->sas_ss_sp = (unsigned long) ss_sp;
2403 current->sas_ss_size = ss_size;
2408 if (copy_to_user(uoss, &oss, sizeof(oss)))
2417 #ifdef __ARCH_WANT_SYS_SIGPENDING
2420 sys_sigpending(old_sigset_t __user *set)
2422 return do_sigpending(set, sizeof(*set));
2427 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2428 /* Some platforms have their own version with special arguments others
2429 support only sys_rt_sigprocmask. */
2432 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2435 old_sigset_t old_set, new_set;
2439 if (copy_from_user(&new_set, set, sizeof(*set)))
2441 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2443 spin_lock_irq(¤t->sighand->siglock);
2444 old_set = current->blocked.sig[0];
2452 sigaddsetmask(¤t->blocked, new_set);
2455 sigdelsetmask(¤t->blocked, new_set);
2458 current->blocked.sig[0] = new_set;
2462 recalc_sigpending();
2463 spin_unlock_irq(¤t->sighand->siglock);
2469 old_set = current->blocked.sig[0];
2472 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2479 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2481 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2483 sys_rt_sigaction(int sig,
2484 const struct sigaction __user *act,
2485 struct sigaction __user *oact,
2488 struct k_sigaction new_sa, old_sa;
2491 /* XXX: Don't preclude handling different sized sigset_t's. */
2492 if (sigsetsize != sizeof(sigset_t))
2496 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2500 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2503 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2509 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2511 #ifdef __ARCH_WANT_SYS_SGETMASK
2514 * For backwards compatibility. Functionality superseded by sigprocmask.
2520 return current->blocked.sig[0];
2524 sys_ssetmask(int newmask)
2528 spin_lock_irq(¤t->sighand->siglock);
2529 old = current->blocked.sig[0];
2531 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2533 recalc_sigpending();
2534 spin_unlock_irq(¤t->sighand->siglock);
2538 #endif /* __ARCH_WANT_SGETMASK */
2540 #ifdef __ARCH_WANT_SYS_SIGNAL
2542 * For backwards compatibility. Functionality superseded by sigaction.
2544 asmlinkage unsigned long
2545 sys_signal(int sig, __sighandler_t handler)
2547 struct k_sigaction new_sa, old_sa;
2550 new_sa.sa.sa_handler = handler;
2551 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2552 sigemptyset(&new_sa.sa.sa_mask);
2554 ret = do_sigaction(sig, &new_sa, &old_sa);
2556 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2558 #endif /* __ARCH_WANT_SYS_SIGNAL */
2560 #ifdef __ARCH_WANT_SYS_PAUSE
2565 current->state = TASK_INTERRUPTIBLE;
2567 return -ERESTARTNOHAND;
2572 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2573 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2577 /* XXX: Don't preclude handling different sized sigset_t's. */
2578 if (sigsetsize != sizeof(sigset_t))
2581 if (copy_from_user(&newset, unewset, sizeof(newset)))
2583 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2585 spin_lock_irq(¤t->sighand->siglock);
2586 current->saved_sigmask = current->blocked;
2587 current->blocked = newset;
2588 recalc_sigpending();
2589 spin_unlock_irq(¤t->sighand->siglock);
2591 current->state = TASK_INTERRUPTIBLE;
2593 set_restore_sigmask();
2594 return -ERESTARTNOHAND;
2596 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2598 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2603 void __init signals_init(void)
2605 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);