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/ratelimit.h>
26 #include <linux/tracehook.h>
27 #include <linux/capability.h>
28 #include <linux/freezer.h>
29 #include <linux/pid_namespace.h>
30 #include <linux/nsproxy.h>
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/signal.h>
34 #include <asm/param.h>
35 #include <asm/uaccess.h>
36 #include <asm/unistd.h>
37 #include <asm/siginfo.h>
38 #include "audit.h" /* audit_signal_info() */
41 * SLAB caches for signal bits.
44 static struct kmem_cache *sigqueue_cachep;
46 int print_fatal_signals __read_mostly;
48 static void __user *sig_handler(struct task_struct *t, int sig)
50 return t->sighand->action[sig - 1].sa.sa_handler;
53 static int sig_handler_ignored(void __user *handler, int sig)
55 /* Is it explicitly or implicitly ignored? */
56 return handler == SIG_IGN ||
57 (handler == SIG_DFL && sig_kernel_ignore(sig));
60 static int sig_task_ignored(struct task_struct *t, int sig,
65 handler = sig_handler(t, sig);
67 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
68 handler == SIG_DFL && !from_ancestor_ns)
71 return sig_handler_ignored(handler, sig);
74 static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
77 * Blocked signals are never ignored, since the
78 * signal handler may change by the time it is
81 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
84 if (!sig_task_ignored(t, sig, from_ancestor_ns))
88 * Tracers may want to know about even ignored signals.
90 return !tracehook_consider_ignored_signal(t, sig);
94 * Re-calculate pending state from the set of locally pending
95 * signals, globally pending signals, and blocked signals.
97 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
102 switch (_NSIG_WORDS) {
104 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
105 ready |= signal->sig[i] &~ blocked->sig[i];
108 case 4: ready = signal->sig[3] &~ blocked->sig[3];
109 ready |= signal->sig[2] &~ blocked->sig[2];
110 ready |= signal->sig[1] &~ blocked->sig[1];
111 ready |= signal->sig[0] &~ blocked->sig[0];
114 case 2: ready = signal->sig[1] &~ blocked->sig[1];
115 ready |= signal->sig[0] &~ blocked->sig[0];
118 case 1: ready = signal->sig[0] &~ blocked->sig[0];
123 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
125 static int recalc_sigpending_tsk(struct task_struct *t)
127 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
128 PENDING(&t->pending, &t->blocked) ||
129 PENDING(&t->signal->shared_pending, &t->blocked)) {
130 set_tsk_thread_flag(t, TIF_SIGPENDING);
134 * We must never clear the flag in another thread, or in current
135 * when it's possible the current syscall is returning -ERESTART*.
136 * So we don't clear it here, and only callers who know they should do.
142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
143 * This is superfluous when called on current, the wakeup is a harmless no-op.
145 void recalc_sigpending_and_wake(struct task_struct *t)
147 if (recalc_sigpending_tsk(t))
148 signal_wake_up(t, 0);
151 void recalc_sigpending(void)
153 if (unlikely(tracehook_force_sigpending()))
154 set_thread_flag(TIF_SIGPENDING);
155 else if (!recalc_sigpending_tsk(current) && !freezing(current))
156 clear_thread_flag(TIF_SIGPENDING);
160 /* Given the mask, find the first available signal that should be serviced. */
162 #define SYNCHRONOUS_MASK \
163 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
164 sigmask(SIGTRAP) | sigmask(SIGFPE))
166 int next_signal(struct sigpending *pending, sigset_t *mask)
168 unsigned long i, *s, *m, x;
171 s = pending->signal.sig;
175 * Handle the first word specially: it contains the
176 * synchronous signals that need to be dequeued first.
180 if (x & SYNCHRONOUS_MASK)
181 x &= SYNCHRONOUS_MASK;
186 switch (_NSIG_WORDS) {
188 for (i = 1; i < _NSIG_WORDS; ++i) {
192 sig = ffz(~x) + i*_NSIG_BPW + 1;
201 sig = ffz(~x) + _NSIG_BPW + 1;
212 static inline void print_dropped_signal(int sig)
214 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
216 if (!print_fatal_signals)
219 if (!__ratelimit(&ratelimit_state))
222 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
223 current->comm, current->pid, sig);
227 * task_clear_jobctl_trapping - clear jobctl trapping bit
230 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
231 * Clear it and wake up the ptracer. Note that we don't need any further
232 * locking. @task->siglock guarantees that @task->parent points to the
236 * Must be called with @task->sighand->siglock held.
238 static void task_clear_jobctl_trapping(struct task_struct *task)
240 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
241 task->jobctl &= ~JOBCTL_TRAPPING;
242 __wake_up_sync_key(&task->parent->signal->wait_chldexit,
243 TASK_UNINTERRUPTIBLE, 1, task);
248 * task_clear_jobctl_pending - clear jobctl pending bits
250 * @mask: pending bits to clear
252 * Clear @mask from @task->jobctl. @mask must be subset of
253 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
254 * STOP bits are cleared together.
256 * If clearing of @mask leaves no stop or trap pending, this function calls
257 * task_clear_jobctl_trapping().
260 * Must be called with @task->sighand->siglock held.
262 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
264 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
266 if (mask & JOBCTL_STOP_PENDING)
267 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
269 task->jobctl &= ~mask;
271 if (!(task->jobctl & JOBCTL_PENDING_MASK))
272 task_clear_jobctl_trapping(task);
276 * task_participate_group_stop - participate in a group stop
277 * @task: task participating in a group stop
279 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
280 * Group stop states are cleared and the group stop count is consumed if
281 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
282 * stop, the appropriate %SIGNAL_* flags are set.
285 * Must be called with @task->sighand->siglock held.
288 * %true if group stop completion should be notified to the parent, %false
291 static bool task_participate_group_stop(struct task_struct *task)
293 struct signal_struct *sig = task->signal;
294 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
296 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
298 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
303 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
304 sig->group_stop_count--;
307 * Tell the caller to notify completion iff we are entering into a
308 * fresh group stop. Read comment in do_signal_stop() for details.
310 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
311 sig->flags = SIGNAL_STOP_STOPPED;
318 * allocate a new signal queue record
319 * - this may be called without locks if and only if t == current, otherwise an
320 * appropriate lock must be held to stop the target task from exiting
322 static struct sigqueue *
323 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
325 struct sigqueue *q = NULL;
326 struct user_struct *user;
329 * Protect access to @t credentials. This can go away when all
330 * callers hold rcu read lock.
333 user = get_uid(__task_cred(t)->user);
334 atomic_inc(&user->sigpending);
337 if (override_rlimit ||
338 atomic_read(&user->sigpending) <=
339 task_rlimit(t, RLIMIT_SIGPENDING)) {
340 q = kmem_cache_alloc(sigqueue_cachep, flags);
342 print_dropped_signal(sig);
345 if (unlikely(q == NULL)) {
346 atomic_dec(&user->sigpending);
349 INIT_LIST_HEAD(&q->list);
357 static void __sigqueue_free(struct sigqueue *q)
359 if (q->flags & SIGQUEUE_PREALLOC)
361 atomic_dec(&q->user->sigpending);
363 kmem_cache_free(sigqueue_cachep, q);
366 void flush_sigqueue(struct sigpending *queue)
370 sigemptyset(&queue->signal);
371 while (!list_empty(&queue->list)) {
372 q = list_entry(queue->list.next, struct sigqueue , list);
373 list_del_init(&q->list);
379 * Flush all pending signals for a task.
381 void __flush_signals(struct task_struct *t)
383 clear_tsk_thread_flag(t, TIF_SIGPENDING);
384 flush_sigqueue(&t->pending);
385 flush_sigqueue(&t->signal->shared_pending);
388 void flush_signals(struct task_struct *t)
392 spin_lock_irqsave(&t->sighand->siglock, flags);
394 spin_unlock_irqrestore(&t->sighand->siglock, flags);
397 static void __flush_itimer_signals(struct sigpending *pending)
399 sigset_t signal, retain;
400 struct sigqueue *q, *n;
402 signal = pending->signal;
403 sigemptyset(&retain);
405 list_for_each_entry_safe(q, n, &pending->list, list) {
406 int sig = q->info.si_signo;
408 if (likely(q->info.si_code != SI_TIMER)) {
409 sigaddset(&retain, sig);
411 sigdelset(&signal, sig);
412 list_del_init(&q->list);
417 sigorsets(&pending->signal, &signal, &retain);
420 void flush_itimer_signals(void)
422 struct task_struct *tsk = current;
425 spin_lock_irqsave(&tsk->sighand->siglock, flags);
426 __flush_itimer_signals(&tsk->pending);
427 __flush_itimer_signals(&tsk->signal->shared_pending);
428 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
431 void ignore_signals(struct task_struct *t)
435 for (i = 0; i < _NSIG; ++i)
436 t->sighand->action[i].sa.sa_handler = SIG_IGN;
442 * Flush all handlers for a task.
446 flush_signal_handlers(struct task_struct *t, int force_default)
449 struct k_sigaction *ka = &t->sighand->action[0];
450 for (i = _NSIG ; i != 0 ; i--) {
451 if (force_default || ka->sa.sa_handler != SIG_IGN)
452 ka->sa.sa_handler = SIG_DFL;
454 sigemptyset(&ka->sa.sa_mask);
459 int unhandled_signal(struct task_struct *tsk, int sig)
461 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
462 if (is_global_init(tsk))
464 if (handler != SIG_IGN && handler != SIG_DFL)
466 return !tracehook_consider_fatal_signal(tsk, sig);
470 * Notify the system that a driver wants to block all signals for this
471 * process, and wants to be notified if any signals at all were to be
472 * sent/acted upon. If the notifier routine returns non-zero, then the
473 * signal will be acted upon after all. If the notifier routine returns 0,
474 * then then signal will be blocked. Only one block per process is
475 * allowed. priv is a pointer to private data that the notifier routine
476 * can use to determine if the signal should be blocked or not.
479 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
483 spin_lock_irqsave(¤t->sighand->siglock, flags);
484 current->notifier_mask = mask;
485 current->notifier_data = priv;
486 current->notifier = notifier;
487 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
490 /* Notify the system that blocking has ended. */
493 unblock_all_signals(void)
497 spin_lock_irqsave(¤t->sighand->siglock, flags);
498 current->notifier = NULL;
499 current->notifier_data = NULL;
501 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
504 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
506 struct sigqueue *q, *first = NULL;
509 * Collect the siginfo appropriate to this signal. Check if
510 * there is another siginfo for the same signal.
512 list_for_each_entry(q, &list->list, list) {
513 if (q->info.si_signo == sig) {
520 sigdelset(&list->signal, sig);
524 list_del_init(&first->list);
525 copy_siginfo(info, &first->info);
526 __sigqueue_free(first);
529 * Ok, it wasn't in the queue. This must be
530 * a fast-pathed signal or we must have been
531 * out of queue space. So zero out the info.
533 info->si_signo = sig;
535 info->si_code = SI_USER;
541 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
544 int sig = next_signal(pending, mask);
547 if (current->notifier) {
548 if (sigismember(current->notifier_mask, sig)) {
549 if (!(current->notifier)(current->notifier_data)) {
550 clear_thread_flag(TIF_SIGPENDING);
556 collect_signal(sig, pending, info);
563 * Dequeue a signal and return the element to the caller, which is
564 * expected to free it.
566 * All callers have to hold the siglock.
568 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
572 /* We only dequeue private signals from ourselves, we don't let
573 * signalfd steal them
575 signr = __dequeue_signal(&tsk->pending, mask, info);
577 signr = __dequeue_signal(&tsk->signal->shared_pending,
582 * itimers are process shared and we restart periodic
583 * itimers in the signal delivery path to prevent DoS
584 * attacks in the high resolution timer case. This is
585 * compliant with the old way of self-restarting
586 * itimers, as the SIGALRM is a legacy signal and only
587 * queued once. Changing the restart behaviour to
588 * restart the timer in the signal dequeue path is
589 * reducing the timer noise on heavy loaded !highres
592 if (unlikely(signr == SIGALRM)) {
593 struct hrtimer *tmr = &tsk->signal->real_timer;
595 if (!hrtimer_is_queued(tmr) &&
596 tsk->signal->it_real_incr.tv64 != 0) {
597 hrtimer_forward(tmr, tmr->base->get_time(),
598 tsk->signal->it_real_incr);
599 hrtimer_restart(tmr);
608 if (unlikely(sig_kernel_stop(signr))) {
610 * Set a marker that we have dequeued a stop signal. Our
611 * caller might release the siglock and then the pending
612 * stop signal it is about to process is no longer in the
613 * pending bitmasks, but must still be cleared by a SIGCONT
614 * (and overruled by a SIGKILL). So those cases clear this
615 * shared flag after we've set it. Note that this flag may
616 * remain set after the signal we return is ignored or
617 * handled. That doesn't matter because its only purpose
618 * is to alert stop-signal processing code when another
619 * processor has come along and cleared the flag.
621 current->jobctl |= JOBCTL_STOP_DEQUEUED;
623 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
625 * Release the siglock to ensure proper locking order
626 * of timer locks outside of siglocks. Note, we leave
627 * irqs disabled here, since the posix-timers code is
628 * about to disable them again anyway.
630 spin_unlock(&tsk->sighand->siglock);
631 do_schedule_next_timer(info);
632 spin_lock(&tsk->sighand->siglock);
638 * Tell a process that it has a new active signal..
640 * NOTE! we rely on the previous spin_lock to
641 * lock interrupts for us! We can only be called with
642 * "siglock" held, and the local interrupt must
643 * have been disabled when that got acquired!
645 * No need to set need_resched since signal event passing
646 * goes through ->blocked
648 void signal_wake_up(struct task_struct *t, int resume)
652 set_tsk_thread_flag(t, TIF_SIGPENDING);
655 * For SIGKILL, we want to wake it up in the stopped/traced/killable
656 * case. We don't check t->state here because there is a race with it
657 * executing another processor and just now entering stopped state.
658 * By using wake_up_state, we ensure the process will wake up and
659 * handle its death signal.
661 mask = TASK_INTERRUPTIBLE;
663 mask |= TASK_WAKEKILL;
664 if (!wake_up_state(t, mask))
669 * Remove signals in mask from the pending set and queue.
670 * Returns 1 if any signals were found.
672 * All callers must be holding the siglock.
674 * This version takes a sigset mask and looks at all signals,
675 * not just those in the first mask word.
677 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
679 struct sigqueue *q, *n;
682 sigandsets(&m, mask, &s->signal);
683 if (sigisemptyset(&m))
686 sigandnsets(&s->signal, &s->signal, mask);
687 list_for_each_entry_safe(q, n, &s->list, list) {
688 if (sigismember(mask, q->info.si_signo)) {
689 list_del_init(&q->list);
696 * Remove signals in mask from the pending set and queue.
697 * Returns 1 if any signals were found.
699 * All callers must be holding the siglock.
701 static int rm_from_queue(unsigned long mask, struct sigpending *s)
703 struct sigqueue *q, *n;
705 if (!sigtestsetmask(&s->signal, mask))
708 sigdelsetmask(&s->signal, mask);
709 list_for_each_entry_safe(q, n, &s->list, list) {
710 if (q->info.si_signo < SIGRTMIN &&
711 (mask & sigmask(q->info.si_signo))) {
712 list_del_init(&q->list);
719 static inline int is_si_special(const struct siginfo *info)
721 return info <= SEND_SIG_FORCED;
724 static inline bool si_fromuser(const struct siginfo *info)
726 return info == SEND_SIG_NOINFO ||
727 (!is_si_special(info) && SI_FROMUSER(info));
731 * called with RCU read lock from check_kill_permission()
733 static int kill_ok_by_cred(struct task_struct *t)
735 const struct cred *cred = current_cred();
736 const struct cred *tcred = __task_cred(t);
738 if (cred->user->user_ns == tcred->user->user_ns &&
739 (cred->euid == tcred->suid ||
740 cred->euid == tcred->uid ||
741 cred->uid == tcred->suid ||
742 cred->uid == tcred->uid))
745 if (ns_capable(tcred->user->user_ns, CAP_KILL))
752 * Bad permissions for sending the signal
753 * - the caller must hold the RCU read lock
755 static int check_kill_permission(int sig, struct siginfo *info,
756 struct task_struct *t)
761 if (!valid_signal(sig))
764 if (!si_fromuser(info))
767 error = audit_signal_info(sig, t); /* Let audit system see the signal */
771 if (!same_thread_group(current, t) &&
772 !kill_ok_by_cred(t)) {
775 sid = task_session(t);
777 * We don't return the error if sid == NULL. The
778 * task was unhashed, the caller must notice this.
780 if (!sid || sid == task_session(current))
787 return security_task_kill(t, info, sig, 0);
791 * Handle magic process-wide effects of stop/continue signals. Unlike
792 * the signal actions, these happen immediately at signal-generation
793 * time regardless of blocking, ignoring, or handling. This does the
794 * actual continuing for SIGCONT, but not the actual stopping for stop
795 * signals. The process stop is done as a signal action for SIG_DFL.
797 * Returns true if the signal should be actually delivered, otherwise
798 * it should be dropped.
800 static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
802 struct signal_struct *signal = p->signal;
803 struct task_struct *t;
805 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
807 * The process is in the middle of dying, nothing to do.
809 } else if (sig_kernel_stop(sig)) {
811 * This is a stop signal. Remove SIGCONT from all queues.
813 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
816 rm_from_queue(sigmask(SIGCONT), &t->pending);
817 } while_each_thread(p, t);
818 } else if (sig == SIGCONT) {
821 * Remove all stop signals from all queues, wake all threads.
823 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
826 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
827 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
828 wake_up_state(t, __TASK_STOPPED);
829 } while_each_thread(p, t);
832 * Notify the parent with CLD_CONTINUED if we were stopped.
834 * If we were in the middle of a group stop, we pretend it
835 * was already finished, and then continued. Since SIGCHLD
836 * doesn't queue we report only CLD_STOPPED, as if the next
837 * CLD_CONTINUED was dropped.
840 if (signal->flags & SIGNAL_STOP_STOPPED)
841 why |= SIGNAL_CLD_CONTINUED;
842 else if (signal->group_stop_count)
843 why |= SIGNAL_CLD_STOPPED;
847 * The first thread which returns from do_signal_stop()
848 * will take ->siglock, notice SIGNAL_CLD_MASK, and
849 * notify its parent. See get_signal_to_deliver().
851 signal->flags = why | SIGNAL_STOP_CONTINUED;
852 signal->group_stop_count = 0;
853 signal->group_exit_code = 0;
857 return !sig_ignored(p, sig, from_ancestor_ns);
861 * Test if P wants to take SIG. After we've checked all threads with this,
862 * it's equivalent to finding no threads not blocking SIG. Any threads not
863 * blocking SIG were ruled out because they are not running and already
864 * have pending signals. Such threads will dequeue from the shared queue
865 * as soon as they're available, so putting the signal on the shared queue
866 * will be equivalent to sending it to one such thread.
868 static inline int wants_signal(int sig, struct task_struct *p)
870 if (sigismember(&p->blocked, sig))
872 if (p->flags & PF_EXITING)
876 if (task_is_stopped_or_traced(p))
878 return task_curr(p) || !signal_pending(p);
881 static void complete_signal(int sig, struct task_struct *p, int group)
883 struct signal_struct *signal = p->signal;
884 struct task_struct *t;
887 * Now find a thread we can wake up to take the signal off the queue.
889 * If the main thread wants the signal, it gets first crack.
890 * Probably the least surprising to the average bear.
892 if (wants_signal(sig, p))
894 else if (!group || thread_group_empty(p))
896 * There is just one thread and it does not need to be woken.
897 * It will dequeue unblocked signals before it runs again.
902 * Otherwise try to find a suitable thread.
904 t = signal->curr_target;
905 while (!wants_signal(sig, t)) {
907 if (t == signal->curr_target)
909 * No thread needs to be woken.
910 * Any eligible threads will see
911 * the signal in the queue soon.
915 signal->curr_target = t;
919 * Found a killable thread. If the signal will be fatal,
920 * then start taking the whole group down immediately.
922 if (sig_fatal(p, sig) &&
923 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
924 !sigismember(&t->real_blocked, sig) &&
926 !tracehook_consider_fatal_signal(t, sig))) {
928 * This signal will be fatal to the whole group.
930 if (!sig_kernel_coredump(sig)) {
932 * Start a group exit and wake everybody up.
933 * This way we don't have other threads
934 * running and doing things after a slower
935 * thread has the fatal signal pending.
937 signal->flags = SIGNAL_GROUP_EXIT;
938 signal->group_exit_code = sig;
939 signal->group_stop_count = 0;
942 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
943 sigaddset(&t->pending.signal, SIGKILL);
944 signal_wake_up(t, 1);
945 } while_each_thread(p, t);
951 * The signal is already in the shared-pending queue.
952 * Tell the chosen thread to wake up and dequeue it.
954 signal_wake_up(t, sig == SIGKILL);
958 static inline int legacy_queue(struct sigpending *signals, int sig)
960 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
963 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
964 int group, int from_ancestor_ns)
966 struct sigpending *pending;
970 trace_signal_generate(sig, info, t);
972 assert_spin_locked(&t->sighand->siglock);
974 if (!prepare_signal(sig, t, from_ancestor_ns))
977 pending = group ? &t->signal->shared_pending : &t->pending;
979 * Short-circuit ignored signals and support queuing
980 * exactly one non-rt signal, so that we can get more
981 * detailed information about the cause of the signal.
983 if (legacy_queue(pending, sig))
986 * fast-pathed signals for kernel-internal things like SIGSTOP
989 if (info == SEND_SIG_FORCED)
993 * Real-time signals must be queued if sent by sigqueue, or
994 * some other real-time mechanism. It is implementation
995 * defined whether kill() does so. We attempt to do so, on
996 * the principle of least surprise, but since kill is not
997 * allowed to fail with EAGAIN when low on memory we just
998 * make sure at least one signal gets delivered and don't
999 * pass on the info struct.
1002 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1004 override_rlimit = 0;
1006 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1009 list_add_tail(&q->list, &pending->list);
1010 switch ((unsigned long) info) {
1011 case (unsigned long) SEND_SIG_NOINFO:
1012 q->info.si_signo = sig;
1013 q->info.si_errno = 0;
1014 q->info.si_code = SI_USER;
1015 q->info.si_pid = task_tgid_nr_ns(current,
1016 task_active_pid_ns(t));
1017 q->info.si_uid = current_uid();
1019 case (unsigned long) SEND_SIG_PRIV:
1020 q->info.si_signo = sig;
1021 q->info.si_errno = 0;
1022 q->info.si_code = SI_KERNEL;
1027 copy_siginfo(&q->info, info);
1028 if (from_ancestor_ns)
1032 } else if (!is_si_special(info)) {
1033 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1035 * Queue overflow, abort. We may abort if the
1036 * signal was rt and sent by user using something
1037 * other than kill().
1039 trace_signal_overflow_fail(sig, group, info);
1043 * This is a silent loss of information. We still
1044 * send the signal, but the *info bits are lost.
1046 trace_signal_lose_info(sig, group, info);
1051 signalfd_notify(t, sig);
1052 sigaddset(&pending->signal, sig);
1053 complete_signal(sig, t, group);
1057 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1060 int from_ancestor_ns = 0;
1062 #ifdef CONFIG_PID_NS
1063 from_ancestor_ns = si_fromuser(info) &&
1064 !task_pid_nr_ns(current, task_active_pid_ns(t));
1067 return __send_signal(sig, info, t, group, from_ancestor_ns);
1070 static void print_fatal_signal(struct pt_regs *regs, int signr)
1072 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1073 current->comm, task_pid_nr(current), signr);
1075 #if defined(__i386__) && !defined(__arch_um__)
1076 printk("code at %08lx: ", regs->ip);
1079 for (i = 0; i < 16; i++) {
1082 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1084 printk("%02x ", insn);
1094 static int __init setup_print_fatal_signals(char *str)
1096 get_option (&str, &print_fatal_signals);
1101 __setup("print-fatal-signals=", setup_print_fatal_signals);
1104 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1106 return send_signal(sig, info, p, 1);
1110 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1112 return send_signal(sig, info, t, 0);
1115 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1118 unsigned long flags;
1121 if (lock_task_sighand(p, &flags)) {
1122 ret = send_signal(sig, info, p, group);
1123 unlock_task_sighand(p, &flags);
1130 * Force a signal that the process can't ignore: if necessary
1131 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1133 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1134 * since we do not want to have a signal handler that was blocked
1135 * be invoked when user space had explicitly blocked it.
1137 * We don't want to have recursive SIGSEGV's etc, for example,
1138 * that is why we also clear SIGNAL_UNKILLABLE.
1141 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1143 unsigned long int flags;
1144 int ret, blocked, ignored;
1145 struct k_sigaction *action;
1147 spin_lock_irqsave(&t->sighand->siglock, flags);
1148 action = &t->sighand->action[sig-1];
1149 ignored = action->sa.sa_handler == SIG_IGN;
1150 blocked = sigismember(&t->blocked, sig);
1151 if (blocked || ignored) {
1152 action->sa.sa_handler = SIG_DFL;
1154 sigdelset(&t->blocked, sig);
1155 recalc_sigpending_and_wake(t);
1158 if (action->sa.sa_handler == SIG_DFL)
1159 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1160 ret = specific_send_sig_info(sig, info, t);
1161 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1167 * Nuke all other threads in the group.
1169 int zap_other_threads(struct task_struct *p)
1171 struct task_struct *t = p;
1174 p->signal->group_stop_count = 0;
1176 while_each_thread(p, t) {
1177 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1180 /* Don't bother with already dead threads */
1183 sigaddset(&t->pending.signal, SIGKILL);
1184 signal_wake_up(t, 1);
1190 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1191 unsigned long *flags)
1193 struct sighand_struct *sighand;
1197 sighand = rcu_dereference(tsk->sighand);
1198 if (unlikely(sighand == NULL))
1201 spin_lock_irqsave(&sighand->siglock, *flags);
1202 if (likely(sighand == tsk->sighand))
1204 spin_unlock_irqrestore(&sighand->siglock, *flags);
1212 * send signal info to all the members of a group
1214 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1219 ret = check_kill_permission(sig, info, p);
1223 ret = do_send_sig_info(sig, info, p, true);
1229 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1230 * control characters do (^C, ^Z etc)
1231 * - the caller must hold at least a readlock on tasklist_lock
1233 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1235 struct task_struct *p = NULL;
1236 int retval, success;
1240 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1241 int err = group_send_sig_info(sig, info, p);
1244 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1245 return success ? 0 : retval;
1248 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1251 struct task_struct *p;
1255 p = pid_task(pid, PIDTYPE_PID);
1257 error = group_send_sig_info(sig, info, p);
1258 if (unlikely(error == -ESRCH))
1260 * The task was unhashed in between, try again.
1261 * If it is dead, pid_task() will return NULL,
1262 * if we race with de_thread() it will find the
1272 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1276 error = kill_pid_info(sig, info, find_vpid(pid));
1281 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1282 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1283 uid_t uid, uid_t euid, u32 secid)
1286 struct task_struct *p;
1287 const struct cred *pcred;
1288 unsigned long flags;
1290 if (!valid_signal(sig))
1294 p = pid_task(pid, PIDTYPE_PID);
1299 pcred = __task_cred(p);
1300 if (si_fromuser(info) &&
1301 euid != pcred->suid && euid != pcred->uid &&
1302 uid != pcred->suid && uid != pcred->uid) {
1306 ret = security_task_kill(p, info, sig, secid);
1311 if (lock_task_sighand(p, &flags)) {
1312 ret = __send_signal(sig, info, p, 1, 0);
1313 unlock_task_sighand(p, &flags);
1321 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1324 * kill_something_info() interprets pid in interesting ways just like kill(2).
1326 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1327 * is probably wrong. Should make it like BSD or SYSV.
1330 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1336 ret = kill_pid_info(sig, info, find_vpid(pid));
1341 read_lock(&tasklist_lock);
1343 ret = __kill_pgrp_info(sig, info,
1344 pid ? find_vpid(-pid) : task_pgrp(current));
1346 int retval = 0, count = 0;
1347 struct task_struct * p;
1349 for_each_process(p) {
1350 if (task_pid_vnr(p) > 1 &&
1351 !same_thread_group(p, current)) {
1352 int err = group_send_sig_info(sig, info, p);
1358 ret = count ? retval : -ESRCH;
1360 read_unlock(&tasklist_lock);
1366 * These are for backward compatibility with the rest of the kernel source.
1369 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1372 * Make sure legacy kernel users don't send in bad values
1373 * (normal paths check this in check_kill_permission).
1375 if (!valid_signal(sig))
1378 return do_send_sig_info(sig, info, p, false);
1381 #define __si_special(priv) \
1382 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1385 send_sig(int sig, struct task_struct *p, int priv)
1387 return send_sig_info(sig, __si_special(priv), p);
1391 force_sig(int sig, struct task_struct *p)
1393 force_sig_info(sig, SEND_SIG_PRIV, p);
1397 * When things go south during signal handling, we
1398 * will force a SIGSEGV. And if the signal that caused
1399 * the problem was already a SIGSEGV, we'll want to
1400 * make sure we don't even try to deliver the signal..
1403 force_sigsegv(int sig, struct task_struct *p)
1405 if (sig == SIGSEGV) {
1406 unsigned long flags;
1407 spin_lock_irqsave(&p->sighand->siglock, flags);
1408 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1409 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1411 force_sig(SIGSEGV, p);
1415 int kill_pgrp(struct pid *pid, int sig, int priv)
1419 read_lock(&tasklist_lock);
1420 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1421 read_unlock(&tasklist_lock);
1425 EXPORT_SYMBOL(kill_pgrp);
1427 int kill_pid(struct pid *pid, int sig, int priv)
1429 return kill_pid_info(sig, __si_special(priv), pid);
1431 EXPORT_SYMBOL(kill_pid);
1434 * These functions support sending signals using preallocated sigqueue
1435 * structures. This is needed "because realtime applications cannot
1436 * afford to lose notifications of asynchronous events, like timer
1437 * expirations or I/O completions". In the case of POSIX Timers
1438 * we allocate the sigqueue structure from the timer_create. If this
1439 * allocation fails we are able to report the failure to the application
1440 * with an EAGAIN error.
1442 struct sigqueue *sigqueue_alloc(void)
1444 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1447 q->flags |= SIGQUEUE_PREALLOC;
1452 void sigqueue_free(struct sigqueue *q)
1454 unsigned long flags;
1455 spinlock_t *lock = ¤t->sighand->siglock;
1457 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1459 * We must hold ->siglock while testing q->list
1460 * to serialize with collect_signal() or with
1461 * __exit_signal()->flush_sigqueue().
1463 spin_lock_irqsave(lock, flags);
1464 q->flags &= ~SIGQUEUE_PREALLOC;
1466 * If it is queued it will be freed when dequeued,
1467 * like the "regular" sigqueue.
1469 if (!list_empty(&q->list))
1471 spin_unlock_irqrestore(lock, flags);
1477 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1479 int sig = q->info.si_signo;
1480 struct sigpending *pending;
1481 unsigned long flags;
1484 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1487 if (!likely(lock_task_sighand(t, &flags)))
1490 ret = 1; /* the signal is ignored */
1491 if (!prepare_signal(sig, t, 0))
1495 if (unlikely(!list_empty(&q->list))) {
1497 * If an SI_TIMER entry is already queue just increment
1498 * the overrun count.
1500 BUG_ON(q->info.si_code != SI_TIMER);
1501 q->info.si_overrun++;
1504 q->info.si_overrun = 0;
1506 signalfd_notify(t, sig);
1507 pending = group ? &t->signal->shared_pending : &t->pending;
1508 list_add_tail(&q->list, &pending->list);
1509 sigaddset(&pending->signal, sig);
1510 complete_signal(sig, t, group);
1512 unlock_task_sighand(t, &flags);
1518 * Let a parent know about the death of a child.
1519 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1521 * Returns -1 if our parent ignored us and so we've switched to
1522 * self-reaping, or else @sig.
1524 int do_notify_parent(struct task_struct *tsk, int sig)
1526 struct siginfo info;
1527 unsigned long flags;
1528 struct sighand_struct *psig;
1533 /* do_notify_parent_cldstop should have been called instead. */
1534 BUG_ON(task_is_stopped_or_traced(tsk));
1536 BUG_ON(!task_ptrace(tsk) &&
1537 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1539 info.si_signo = sig;
1542 * we are under tasklist_lock here so our parent is tied to
1543 * us and cannot exit and release its namespace.
1545 * the only it can is to switch its nsproxy with sys_unshare,
1546 * bu uncharing pid namespaces is not allowed, so we'll always
1547 * see relevant namespace
1549 * write_lock() currently calls preempt_disable() which is the
1550 * same as rcu_read_lock(), but according to Oleg, this is not
1551 * correct to rely on this
1554 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1555 info.si_uid = __task_cred(tsk)->uid;
1558 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1559 tsk->signal->utime));
1560 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1561 tsk->signal->stime));
1563 info.si_status = tsk->exit_code & 0x7f;
1564 if (tsk->exit_code & 0x80)
1565 info.si_code = CLD_DUMPED;
1566 else if (tsk->exit_code & 0x7f)
1567 info.si_code = CLD_KILLED;
1569 info.si_code = CLD_EXITED;
1570 info.si_status = tsk->exit_code >> 8;
1573 psig = tsk->parent->sighand;
1574 spin_lock_irqsave(&psig->siglock, flags);
1575 if (!task_ptrace(tsk) && sig == SIGCHLD &&
1576 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1577 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1579 * We are exiting and our parent doesn't care. POSIX.1
1580 * defines special semantics for setting SIGCHLD to SIG_IGN
1581 * or setting the SA_NOCLDWAIT flag: we should be reaped
1582 * automatically and not left for our parent's wait4 call.
1583 * Rather than having the parent do it as a magic kind of
1584 * signal handler, we just set this to tell do_exit that we
1585 * can be cleaned up without becoming a zombie. Note that
1586 * we still call __wake_up_parent in this case, because a
1587 * blocked sys_wait4 might now return -ECHILD.
1589 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1590 * is implementation-defined: we do (if you don't want
1591 * it, just use SIG_IGN instead).
1593 ret = tsk->exit_signal = -1;
1594 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1597 if (valid_signal(sig) && sig > 0)
1598 __group_send_sig_info(sig, &info, tsk->parent);
1599 __wake_up_parent(tsk, tsk->parent);
1600 spin_unlock_irqrestore(&psig->siglock, flags);
1606 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1607 * @tsk: task reporting the state change
1608 * @for_ptracer: the notification is for ptracer
1609 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1611 * Notify @tsk's parent that the stopped/continued state has changed. If
1612 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1613 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1616 * Must be called with tasklist_lock at least read locked.
1618 static void do_notify_parent_cldstop(struct task_struct *tsk,
1619 bool for_ptracer, int why)
1621 struct siginfo info;
1622 unsigned long flags;
1623 struct task_struct *parent;
1624 struct sighand_struct *sighand;
1627 parent = tsk->parent;
1629 tsk = tsk->group_leader;
1630 parent = tsk->real_parent;
1633 info.si_signo = SIGCHLD;
1636 * see comment in do_notify_parent() about the following 4 lines
1639 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1640 info.si_uid = __task_cred(tsk)->uid;
1643 info.si_utime = cputime_to_clock_t(tsk->utime);
1644 info.si_stime = cputime_to_clock_t(tsk->stime);
1649 info.si_status = SIGCONT;
1652 info.si_status = tsk->signal->group_exit_code & 0x7f;
1655 info.si_status = tsk->exit_code & 0x7f;
1661 sighand = parent->sighand;
1662 spin_lock_irqsave(&sighand->siglock, flags);
1663 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1664 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1665 __group_send_sig_info(SIGCHLD, &info, parent);
1667 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1669 __wake_up_parent(tsk, parent);
1670 spin_unlock_irqrestore(&sighand->siglock, flags);
1673 static inline int may_ptrace_stop(void)
1675 if (!likely(task_ptrace(current)))
1678 * Are we in the middle of do_coredump?
1679 * If so and our tracer is also part of the coredump stopping
1680 * is a deadlock situation, and pointless because our tracer
1681 * is dead so don't allow us to stop.
1682 * If SIGKILL was already sent before the caller unlocked
1683 * ->siglock we must see ->core_state != NULL. Otherwise it
1684 * is safe to enter schedule().
1686 if (unlikely(current->mm->core_state) &&
1687 unlikely(current->mm == current->parent->mm))
1694 * Return non-zero if there is a SIGKILL that should be waking us up.
1695 * Called with the siglock held.
1697 static int sigkill_pending(struct task_struct *tsk)
1699 return sigismember(&tsk->pending.signal, SIGKILL) ||
1700 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1704 * Test whether the target task of the usual cldstop notification - the
1705 * real_parent of @child - is in the same group as the ptracer.
1707 static bool real_parent_is_ptracer(struct task_struct *child)
1709 return same_thread_group(child->parent, child->real_parent);
1713 * This must be called with current->sighand->siglock held.
1715 * This should be the path for all ptrace stops.
1716 * We always set current->last_siginfo while stopped here.
1717 * That makes it a way to test a stopped process for
1718 * being ptrace-stopped vs being job-control-stopped.
1720 * If we actually decide not to stop at all because the tracer
1721 * is gone, we keep current->exit_code unless clear_code.
1723 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1724 __releases(¤t->sighand->siglock)
1725 __acquires(¤t->sighand->siglock)
1727 bool gstop_done = false;
1729 if (arch_ptrace_stop_needed(exit_code, info)) {
1731 * The arch code has something special to do before a
1732 * ptrace stop. This is allowed to block, e.g. for faults
1733 * on user stack pages. We can't keep the siglock while
1734 * calling arch_ptrace_stop, so we must release it now.
1735 * To preserve proper semantics, we must do this before
1736 * any signal bookkeeping like checking group_stop_count.
1737 * Meanwhile, a SIGKILL could come in before we retake the
1738 * siglock. That must prevent us from sleeping in TASK_TRACED.
1739 * So after regaining the lock, we must check for SIGKILL.
1741 spin_unlock_irq(¤t->sighand->siglock);
1742 arch_ptrace_stop(exit_code, info);
1743 spin_lock_irq(¤t->sighand->siglock);
1744 if (sigkill_pending(current))
1749 * We're committing to trapping. TRACED should be visible before
1750 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1751 * Also, transition to TRACED and updates to ->jobctl should be
1752 * atomic with respect to siglock and should be done after the arch
1753 * hook as siglock is released and regrabbed across it.
1755 set_current_state(TASK_TRACED);
1757 current->last_siginfo = info;
1758 current->exit_code = exit_code;
1761 * If @why is CLD_STOPPED, we're trapping to participate in a group
1762 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1763 * while siglock was released for the arch hook, PENDING could be
1764 * clear now. We act as if SIGCONT is received after TASK_TRACED
1765 * is entered - ignore it.
1767 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1768 gstop_done = task_participate_group_stop(current);
1770 /* entering a trap, clear TRAPPING */
1771 task_clear_jobctl_trapping(current);
1773 spin_unlock_irq(¤t->sighand->siglock);
1774 read_lock(&tasklist_lock);
1775 if (may_ptrace_stop()) {
1777 * Notify parents of the stop.
1779 * While ptraced, there are two parents - the ptracer and
1780 * the real_parent of the group_leader. The ptracer should
1781 * know about every stop while the real parent is only
1782 * interested in the completion of group stop. The states
1783 * for the two don't interact with each other. Notify
1784 * separately unless they're gonna be duplicates.
1786 do_notify_parent_cldstop(current, true, why);
1787 if (gstop_done && !real_parent_is_ptracer(current))
1788 do_notify_parent_cldstop(current, false, why);
1791 * Don't want to allow preemption here, because
1792 * sys_ptrace() needs this task to be inactive.
1794 * XXX: implement read_unlock_no_resched().
1797 read_unlock(&tasklist_lock);
1798 preempt_enable_no_resched();
1802 * By the time we got the lock, our tracer went away.
1803 * Don't drop the lock yet, another tracer may come.
1805 * If @gstop_done, the ptracer went away between group stop
1806 * completion and here. During detach, it would have set
1807 * JOBCTL_STOP_PENDING on us and we'll re-enter
1808 * TASK_STOPPED in do_signal_stop() on return, so notifying
1809 * the real parent of the group stop completion is enough.
1812 do_notify_parent_cldstop(current, false, why);
1814 __set_current_state(TASK_RUNNING);
1816 current->exit_code = 0;
1817 read_unlock(&tasklist_lock);
1821 * While in TASK_TRACED, we were considered "frozen enough".
1822 * Now that we woke up, it's crucial if we're supposed to be
1823 * frozen that we freeze now before running anything substantial.
1828 * We are back. Now reacquire the siglock before touching
1829 * last_siginfo, so that we are sure to have synchronized with
1830 * any signal-sending on another CPU that wants to examine it.
1832 spin_lock_irq(¤t->sighand->siglock);
1833 current->last_siginfo = NULL;
1836 * Queued signals ignored us while we were stopped for tracing.
1837 * So check for any that we should take before resuming user mode.
1838 * This sets TIF_SIGPENDING, but never clears it.
1840 recalc_sigpending_tsk(current);
1843 void ptrace_notify(int exit_code)
1847 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1849 memset(&info, 0, sizeof info);
1850 info.si_signo = SIGTRAP;
1851 info.si_code = exit_code;
1852 info.si_pid = task_pid_vnr(current);
1853 info.si_uid = current_uid();
1855 /* Let the debugger run. */
1856 spin_lock_irq(¤t->sighand->siglock);
1857 ptrace_stop(exit_code, CLD_TRAPPED, 1, &info);
1858 spin_unlock_irq(¤t->sighand->siglock);
1862 * This performs the stopping for SIGSTOP and other stop signals.
1863 * We have to stop all threads in the thread group.
1864 * Returns non-zero if we've actually stopped and released the siglock.
1865 * Returns zero if we didn't stop and still hold the siglock.
1867 static int do_signal_stop(int signr)
1869 struct signal_struct *sig = current->signal;
1871 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1872 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1873 struct task_struct *t;
1875 /* signr will be recorded in task->jobctl for retries */
1876 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1878 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1879 unlikely(signal_group_exit(sig)))
1882 * There is no group stop already in progress. We must
1885 * While ptraced, a task may be resumed while group stop is
1886 * still in effect and then receive a stop signal and
1887 * initiate another group stop. This deviates from the
1888 * usual behavior as two consecutive stop signals can't
1889 * cause two group stops when !ptraced. That is why we
1890 * also check !task_is_stopped(t) below.
1892 * The condition can be distinguished by testing whether
1893 * SIGNAL_STOP_STOPPED is already set. Don't generate
1894 * group_exit_code in such case.
1896 * This is not necessary for SIGNAL_STOP_CONTINUED because
1897 * an intervening stop signal is required to cause two
1898 * continued events regardless of ptrace.
1900 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1901 sig->group_exit_code = signr;
1903 WARN_ON_ONCE(!task_ptrace(current));
1905 current->jobctl &= ~JOBCTL_STOP_SIGMASK;
1906 current->jobctl |= signr | gstop;
1907 sig->group_stop_count = 1;
1908 for (t = next_thread(current); t != current;
1909 t = next_thread(t)) {
1910 t->jobctl &= ~JOBCTL_STOP_SIGMASK;
1912 * Setting state to TASK_STOPPED for a group
1913 * stop is always done with the siglock held,
1914 * so this check has no races.
1916 if (!(t->flags & PF_EXITING) && !task_is_stopped(t)) {
1917 t->jobctl |= signr | gstop;
1918 sig->group_stop_count++;
1919 signal_wake_up(t, 0);
1924 if (likely(!task_ptrace(current))) {
1928 * If there are no other threads in the group, or if there
1929 * is a group stop in progress and we are the last to stop,
1930 * report to the parent.
1932 if (task_participate_group_stop(current))
1933 notify = CLD_STOPPED;
1935 __set_current_state(TASK_STOPPED);
1936 spin_unlock_irq(¤t->sighand->siglock);
1939 * Notify the parent of the group stop completion. Because
1940 * we're not holding either the siglock or tasklist_lock
1941 * here, ptracer may attach inbetween; however, this is for
1942 * group stop and should always be delivered to the real
1943 * parent of the group leader. The new ptracer will get
1944 * its notification when this task transitions into
1948 read_lock(&tasklist_lock);
1949 do_notify_parent_cldstop(current, false, notify);
1950 read_unlock(&tasklist_lock);
1953 /* Now we don't run again until woken by SIGCONT or SIGKILL */
1956 spin_lock_irq(¤t->sighand->siglock);
1958 ptrace_stop(current->jobctl & JOBCTL_STOP_SIGMASK,
1959 CLD_STOPPED, 0, NULL);
1960 current->exit_code = 0;
1964 * JOBCTL_STOP_PENDING could be set if another group stop has
1965 * started since being woken up or ptrace wants us to transit
1966 * between TASK_STOPPED and TRACED. Retry group stop.
1968 if (current->jobctl & JOBCTL_STOP_PENDING) {
1969 WARN_ON_ONCE(!(current->jobctl & JOBCTL_STOP_SIGMASK));
1973 spin_unlock_irq(¤t->sighand->siglock);
1975 tracehook_finish_jctl();
1980 static int ptrace_signal(int signr, siginfo_t *info,
1981 struct pt_regs *regs, void *cookie)
1983 if (!task_ptrace(current))
1986 ptrace_signal_deliver(regs, cookie);
1988 /* Let the debugger run. */
1989 ptrace_stop(signr, CLD_TRAPPED, 0, info);
1991 /* We're back. Did the debugger cancel the sig? */
1992 signr = current->exit_code;
1996 current->exit_code = 0;
1999 * Update the siginfo structure if the signal has
2000 * changed. If the debugger wanted something
2001 * specific in the siginfo structure then it should
2002 * have updated *info via PTRACE_SETSIGINFO.
2004 if (signr != info->si_signo) {
2005 info->si_signo = signr;
2007 info->si_code = SI_USER;
2008 info->si_pid = task_pid_vnr(current->parent);
2009 info->si_uid = task_uid(current->parent);
2012 /* If the (new) signal is now blocked, requeue it. */
2013 if (sigismember(¤t->blocked, signr)) {
2014 specific_send_sig_info(signr, info, current);
2021 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2022 struct pt_regs *regs, void *cookie)
2024 struct sighand_struct *sighand = current->sighand;
2025 struct signal_struct *signal = current->signal;
2030 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2031 * While in TASK_STOPPED, we were considered "frozen enough".
2032 * Now that we woke up, it's crucial if we're supposed to be
2033 * frozen that we freeze now before running anything substantial.
2037 spin_lock_irq(&sighand->siglock);
2039 * Every stopped thread goes here after wakeup. Check to see if
2040 * we should notify the parent, prepare_signal(SIGCONT) encodes
2041 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2043 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2044 struct task_struct *leader;
2047 if (signal->flags & SIGNAL_CLD_CONTINUED)
2048 why = CLD_CONTINUED;
2052 signal->flags &= ~SIGNAL_CLD_MASK;
2054 spin_unlock_irq(&sighand->siglock);
2057 * Notify the parent that we're continuing. This event is
2058 * always per-process and doesn't make whole lot of sense
2059 * for ptracers, who shouldn't consume the state via
2060 * wait(2) either, but, for backward compatibility, notify
2061 * the ptracer of the group leader too unless it's gonna be
2064 read_lock(&tasklist_lock);
2066 do_notify_parent_cldstop(current, false, why);
2068 leader = current->group_leader;
2069 if (task_ptrace(leader) && !real_parent_is_ptracer(leader))
2070 do_notify_parent_cldstop(leader, true, why);
2072 read_unlock(&tasklist_lock);
2078 struct k_sigaction *ka;
2080 * Tracing can induce an artificial signal and choose sigaction.
2081 * The return value in @signr determines the default action,
2082 * but @info->si_signo is the signal number we will report.
2084 signr = tracehook_get_signal(current, regs, info, return_ka);
2085 if (unlikely(signr < 0))
2087 if (unlikely(signr != 0))
2090 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2094 signr = dequeue_signal(current, ¤t->blocked,
2098 break; /* will return 0 */
2100 if (signr != SIGKILL) {
2101 signr = ptrace_signal(signr, info,
2107 ka = &sighand->action[signr-1];
2110 /* Trace actually delivered signals. */
2111 trace_signal_deliver(signr, info, ka);
2113 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2115 if (ka->sa.sa_handler != SIG_DFL) {
2116 /* Run the handler. */
2119 if (ka->sa.sa_flags & SA_ONESHOT)
2120 ka->sa.sa_handler = SIG_DFL;
2122 break; /* will return non-zero "signr" value */
2126 * Now we are doing the default action for this signal.
2128 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2132 * Global init gets no signals it doesn't want.
2133 * Container-init gets no signals it doesn't want from same
2136 * Note that if global/container-init sees a sig_kernel_only()
2137 * signal here, the signal must have been generated internally
2138 * or must have come from an ancestor namespace. In either
2139 * case, the signal cannot be dropped.
2141 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2142 !sig_kernel_only(signr))
2145 if (sig_kernel_stop(signr)) {
2147 * The default action is to stop all threads in
2148 * the thread group. The job control signals
2149 * do nothing in an orphaned pgrp, but SIGSTOP
2150 * always works. Note that siglock needs to be
2151 * dropped during the call to is_orphaned_pgrp()
2152 * because of lock ordering with tasklist_lock.
2153 * This allows an intervening SIGCONT to be posted.
2154 * We need to check for that and bail out if necessary.
2156 if (signr != SIGSTOP) {
2157 spin_unlock_irq(&sighand->siglock);
2159 /* signals can be posted during this window */
2161 if (is_current_pgrp_orphaned())
2164 spin_lock_irq(&sighand->siglock);
2167 if (likely(do_signal_stop(info->si_signo))) {
2168 /* It released the siglock. */
2173 * We didn't actually stop, due to a race
2174 * with SIGCONT or something like that.
2179 spin_unlock_irq(&sighand->siglock);
2182 * Anything else is fatal, maybe with a core dump.
2184 current->flags |= PF_SIGNALED;
2186 if (sig_kernel_coredump(signr)) {
2187 if (print_fatal_signals)
2188 print_fatal_signal(regs, info->si_signo);
2190 * If it was able to dump core, this kills all
2191 * other threads in the group and synchronizes with
2192 * their demise. If we lost the race with another
2193 * thread getting here, it set group_exit_code
2194 * first and our do_group_exit call below will use
2195 * that value and ignore the one we pass it.
2197 do_coredump(info->si_signo, info->si_signo, regs);
2201 * Death signals, no core dump.
2203 do_group_exit(info->si_signo);
2206 spin_unlock_irq(&sighand->siglock);
2211 * It could be that complete_signal() picked us to notify about the
2212 * group-wide signal. Other threads should be notified now to take
2213 * the shared signals in @which since we will not.
2215 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2218 struct task_struct *t;
2220 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2221 if (sigisemptyset(&retarget))
2225 while_each_thread(tsk, t) {
2226 if (t->flags & PF_EXITING)
2229 if (!has_pending_signals(&retarget, &t->blocked))
2231 /* Remove the signals this thread can handle. */
2232 sigandsets(&retarget, &retarget, &t->blocked);
2234 if (!signal_pending(t))
2235 signal_wake_up(t, 0);
2237 if (sigisemptyset(&retarget))
2242 void exit_signals(struct task_struct *tsk)
2247 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2248 tsk->flags |= PF_EXITING;
2252 spin_lock_irq(&tsk->sighand->siglock);
2254 * From now this task is not visible for group-wide signals,
2255 * see wants_signal(), do_signal_stop().
2257 tsk->flags |= PF_EXITING;
2258 if (!signal_pending(tsk))
2261 unblocked = tsk->blocked;
2262 signotset(&unblocked);
2263 retarget_shared_pending(tsk, &unblocked);
2265 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2266 task_participate_group_stop(tsk))
2267 group_stop = CLD_STOPPED;
2269 spin_unlock_irq(&tsk->sighand->siglock);
2272 * If group stop has completed, deliver the notification. This
2273 * should always go to the real parent of the group leader.
2275 if (unlikely(group_stop)) {
2276 read_lock(&tasklist_lock);
2277 do_notify_parent_cldstop(tsk, false, group_stop);
2278 read_unlock(&tasklist_lock);
2282 EXPORT_SYMBOL(recalc_sigpending);
2283 EXPORT_SYMBOL_GPL(dequeue_signal);
2284 EXPORT_SYMBOL(flush_signals);
2285 EXPORT_SYMBOL(force_sig);
2286 EXPORT_SYMBOL(send_sig);
2287 EXPORT_SYMBOL(send_sig_info);
2288 EXPORT_SYMBOL(sigprocmask);
2289 EXPORT_SYMBOL(block_all_signals);
2290 EXPORT_SYMBOL(unblock_all_signals);
2294 * System call entry points.
2298 * sys_restart_syscall - restart a system call
2300 SYSCALL_DEFINE0(restart_syscall)
2302 struct restart_block *restart = ¤t_thread_info()->restart_block;
2303 return restart->fn(restart);
2306 long do_no_restart_syscall(struct restart_block *param)
2311 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2313 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2314 sigset_t newblocked;
2315 /* A set of now blocked but previously unblocked signals. */
2316 sigandnsets(&newblocked, newset, ¤t->blocked);
2317 retarget_shared_pending(tsk, &newblocked);
2319 tsk->blocked = *newset;
2320 recalc_sigpending();
2324 * set_current_blocked - change current->blocked mask
2327 * It is wrong to change ->blocked directly, this helper should be used
2328 * to ensure the process can't miss a shared signal we are going to block.
2330 void set_current_blocked(const sigset_t *newset)
2332 struct task_struct *tsk = current;
2334 spin_lock_irq(&tsk->sighand->siglock);
2335 __set_task_blocked(tsk, newset);
2336 spin_unlock_irq(&tsk->sighand->siglock);
2340 * This is also useful for kernel threads that want to temporarily
2341 * (or permanently) block certain signals.
2343 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2344 * interface happily blocks "unblockable" signals like SIGKILL
2347 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2349 struct task_struct *tsk = current;
2352 /* Lockless, only current can change ->blocked, never from irq */
2354 *oldset = tsk->blocked;
2358 sigorsets(&newset, &tsk->blocked, set);
2361 sigandnsets(&newset, &tsk->blocked, set);
2370 set_current_blocked(&newset);
2375 * sys_rt_sigprocmask - change the list of currently blocked signals
2376 * @how: whether to add, remove, or set signals
2377 * @set: stores pending signals
2378 * @oset: previous value of signal mask if non-null
2379 * @sigsetsize: size of sigset_t type
2381 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2382 sigset_t __user *, oset, size_t, sigsetsize)
2384 sigset_t old_set, new_set;
2387 /* XXX: Don't preclude handling different sized sigset_t's. */
2388 if (sigsetsize != sizeof(sigset_t))
2391 old_set = current->blocked;
2394 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2396 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2398 error = sigprocmask(how, &new_set, NULL);
2404 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2411 long do_sigpending(void __user *set, unsigned long sigsetsize)
2413 long error = -EINVAL;
2416 if (sigsetsize > sizeof(sigset_t))
2419 spin_lock_irq(¤t->sighand->siglock);
2420 sigorsets(&pending, ¤t->pending.signal,
2421 ¤t->signal->shared_pending.signal);
2422 spin_unlock_irq(¤t->sighand->siglock);
2424 /* Outside the lock because only this thread touches it. */
2425 sigandsets(&pending, ¤t->blocked, &pending);
2428 if (!copy_to_user(set, &pending, sigsetsize))
2436 * sys_rt_sigpending - examine a pending signal that has been raised
2438 * @set: stores pending signals
2439 * @sigsetsize: size of sigset_t type or larger
2441 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2443 return do_sigpending(set, sigsetsize);
2446 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2448 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2452 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2454 if (from->si_code < 0)
2455 return __copy_to_user(to, from, sizeof(siginfo_t))
2458 * If you change siginfo_t structure, please be sure
2459 * this code is fixed accordingly.
2460 * Please remember to update the signalfd_copyinfo() function
2461 * inside fs/signalfd.c too, in case siginfo_t changes.
2462 * It should never copy any pad contained in the structure
2463 * to avoid security leaks, but must copy the generic
2464 * 3 ints plus the relevant union member.
2466 err = __put_user(from->si_signo, &to->si_signo);
2467 err |= __put_user(from->si_errno, &to->si_errno);
2468 err |= __put_user((short)from->si_code, &to->si_code);
2469 switch (from->si_code & __SI_MASK) {
2471 err |= __put_user(from->si_pid, &to->si_pid);
2472 err |= __put_user(from->si_uid, &to->si_uid);
2475 err |= __put_user(from->si_tid, &to->si_tid);
2476 err |= __put_user(from->si_overrun, &to->si_overrun);
2477 err |= __put_user(from->si_ptr, &to->si_ptr);
2480 err |= __put_user(from->si_band, &to->si_band);
2481 err |= __put_user(from->si_fd, &to->si_fd);
2484 err |= __put_user(from->si_addr, &to->si_addr);
2485 #ifdef __ARCH_SI_TRAPNO
2486 err |= __put_user(from->si_trapno, &to->si_trapno);
2488 #ifdef BUS_MCEERR_AO
2490 * Other callers might not initialize the si_lsb field,
2491 * so check explicitly for the right codes here.
2493 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2494 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2498 err |= __put_user(from->si_pid, &to->si_pid);
2499 err |= __put_user(from->si_uid, &to->si_uid);
2500 err |= __put_user(from->si_status, &to->si_status);
2501 err |= __put_user(from->si_utime, &to->si_utime);
2502 err |= __put_user(from->si_stime, &to->si_stime);
2504 case __SI_RT: /* This is not generated by the kernel as of now. */
2505 case __SI_MESGQ: /* But this is */
2506 err |= __put_user(from->si_pid, &to->si_pid);
2507 err |= __put_user(from->si_uid, &to->si_uid);
2508 err |= __put_user(from->si_ptr, &to->si_ptr);
2510 default: /* this is just in case for now ... */
2511 err |= __put_user(from->si_pid, &to->si_pid);
2512 err |= __put_user(from->si_uid, &to->si_uid);
2521 * do_sigtimedwait - wait for queued signals specified in @which
2522 * @which: queued signals to wait for
2523 * @info: if non-null, the signal's siginfo is returned here
2524 * @ts: upper bound on process time suspension
2526 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2527 const struct timespec *ts)
2529 struct task_struct *tsk = current;
2530 long timeout = MAX_SCHEDULE_TIMEOUT;
2531 sigset_t mask = *which;
2535 if (!timespec_valid(ts))
2537 timeout = timespec_to_jiffies(ts);
2539 * We can be close to the next tick, add another one
2540 * to ensure we will wait at least the time asked for.
2542 if (ts->tv_sec || ts->tv_nsec)
2547 * Invert the set of allowed signals to get those we want to block.
2549 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2552 spin_lock_irq(&tsk->sighand->siglock);
2553 sig = dequeue_signal(tsk, &mask, info);
2554 if (!sig && timeout) {
2556 * None ready, temporarily unblock those we're interested
2557 * while we are sleeping in so that we'll be awakened when
2558 * they arrive. Unblocking is always fine, we can avoid
2559 * set_current_blocked().
2561 tsk->real_blocked = tsk->blocked;
2562 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2563 recalc_sigpending();
2564 spin_unlock_irq(&tsk->sighand->siglock);
2566 timeout = schedule_timeout_interruptible(timeout);
2568 spin_lock_irq(&tsk->sighand->siglock);
2569 __set_task_blocked(tsk, &tsk->real_blocked);
2570 siginitset(&tsk->real_blocked, 0);
2571 sig = dequeue_signal(tsk, &mask, info);
2573 spin_unlock_irq(&tsk->sighand->siglock);
2577 return timeout ? -EINTR : -EAGAIN;
2581 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2583 * @uthese: queued signals to wait for
2584 * @uinfo: if non-null, the signal's siginfo is returned here
2585 * @uts: upper bound on process time suspension
2586 * @sigsetsize: size of sigset_t type
2588 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2589 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2597 /* XXX: Don't preclude handling different sized sigset_t's. */
2598 if (sigsetsize != sizeof(sigset_t))
2601 if (copy_from_user(&these, uthese, sizeof(these)))
2605 if (copy_from_user(&ts, uts, sizeof(ts)))
2609 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2611 if (ret > 0 && uinfo) {
2612 if (copy_siginfo_to_user(uinfo, &info))
2620 * sys_kill - send a signal to a process
2621 * @pid: the PID of the process
2622 * @sig: signal to be sent
2624 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2626 struct siginfo info;
2628 info.si_signo = sig;
2630 info.si_code = SI_USER;
2631 info.si_pid = task_tgid_vnr(current);
2632 info.si_uid = current_uid();
2634 return kill_something_info(sig, &info, pid);
2638 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2640 struct task_struct *p;
2644 p = find_task_by_vpid(pid);
2645 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2646 error = check_kill_permission(sig, info, p);
2648 * The null signal is a permissions and process existence
2649 * probe. No signal is actually delivered.
2651 if (!error && sig) {
2652 error = do_send_sig_info(sig, info, p, false);
2654 * If lock_task_sighand() failed we pretend the task
2655 * dies after receiving the signal. The window is tiny,
2656 * and the signal is private anyway.
2658 if (unlikely(error == -ESRCH))
2667 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2669 struct siginfo info;
2671 info.si_signo = sig;
2673 info.si_code = SI_TKILL;
2674 info.si_pid = task_tgid_vnr(current);
2675 info.si_uid = current_uid();
2677 return do_send_specific(tgid, pid, sig, &info);
2681 * sys_tgkill - send signal to one specific thread
2682 * @tgid: the thread group ID of the thread
2683 * @pid: the PID of the thread
2684 * @sig: signal to be sent
2686 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2687 * exists but it's not belonging to the target process anymore. This
2688 * method solves the problem of threads exiting and PIDs getting reused.
2690 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2692 /* This is only valid for single tasks */
2693 if (pid <= 0 || tgid <= 0)
2696 return do_tkill(tgid, pid, sig);
2700 * sys_tkill - send signal to one specific task
2701 * @pid: the PID of the task
2702 * @sig: signal to be sent
2704 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2706 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2708 /* This is only valid for single tasks */
2712 return do_tkill(0, pid, sig);
2716 * sys_rt_sigqueueinfo - send signal information to a signal
2717 * @pid: the PID of the thread
2718 * @sig: signal to be sent
2719 * @uinfo: signal info to be sent
2721 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2722 siginfo_t __user *, uinfo)
2726 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2729 /* Not even root can pretend to send signals from the kernel.
2730 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2732 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2733 /* We used to allow any < 0 si_code */
2734 WARN_ON_ONCE(info.si_code < 0);
2737 info.si_signo = sig;
2739 /* POSIX.1b doesn't mention process groups. */
2740 return kill_proc_info(sig, &info, pid);
2743 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2745 /* This is only valid for single tasks */
2746 if (pid <= 0 || tgid <= 0)
2749 /* Not even root can pretend to send signals from the kernel.
2750 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2752 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2753 /* We used to allow any < 0 si_code */
2754 WARN_ON_ONCE(info->si_code < 0);
2757 info->si_signo = sig;
2759 return do_send_specific(tgid, pid, sig, info);
2762 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2763 siginfo_t __user *, uinfo)
2767 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2770 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2773 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2775 struct task_struct *t = current;
2776 struct k_sigaction *k;
2779 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2782 k = &t->sighand->action[sig-1];
2784 spin_lock_irq(¤t->sighand->siglock);
2789 sigdelsetmask(&act->sa.sa_mask,
2790 sigmask(SIGKILL) | sigmask(SIGSTOP));
2794 * "Setting a signal action to SIG_IGN for a signal that is
2795 * pending shall cause the pending signal to be discarded,
2796 * whether or not it is blocked."
2798 * "Setting a signal action to SIG_DFL for a signal that is
2799 * pending and whose default action is to ignore the signal
2800 * (for example, SIGCHLD), shall cause the pending signal to
2801 * be discarded, whether or not it is blocked"
2803 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2805 sigaddset(&mask, sig);
2806 rm_from_queue_full(&mask, &t->signal->shared_pending);
2808 rm_from_queue_full(&mask, &t->pending);
2810 } while (t != current);
2814 spin_unlock_irq(¤t->sighand->siglock);
2819 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2824 oss.ss_sp = (void __user *) current->sas_ss_sp;
2825 oss.ss_size = current->sas_ss_size;
2826 oss.ss_flags = sas_ss_flags(sp);
2834 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
2836 error = __get_user(ss_sp, &uss->ss_sp) |
2837 __get_user(ss_flags, &uss->ss_flags) |
2838 __get_user(ss_size, &uss->ss_size);
2843 if (on_sig_stack(sp))
2848 * Note - this code used to test ss_flags incorrectly:
2849 * old code may have been written using ss_flags==0
2850 * to mean ss_flags==SS_ONSTACK (as this was the only
2851 * way that worked) - this fix preserves that older
2854 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2857 if (ss_flags == SS_DISABLE) {
2862 if (ss_size < MINSIGSTKSZ)
2866 current->sas_ss_sp = (unsigned long) ss_sp;
2867 current->sas_ss_size = ss_size;
2873 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
2875 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
2876 __put_user(oss.ss_size, &uoss->ss_size) |
2877 __put_user(oss.ss_flags, &uoss->ss_flags);
2884 #ifdef __ARCH_WANT_SYS_SIGPENDING
2887 * sys_sigpending - examine pending signals
2888 * @set: where mask of pending signal is returned
2890 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
2892 return do_sigpending(set, sizeof(*set));
2897 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2899 * sys_sigprocmask - examine and change blocked signals
2900 * @how: whether to add, remove, or set signals
2901 * @nset: signals to add or remove (if non-null)
2902 * @oset: previous value of signal mask if non-null
2904 * Some platforms have their own version with special arguments;
2905 * others support only sys_rt_sigprocmask.
2908 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
2909 old_sigset_t __user *, oset)
2911 old_sigset_t old_set, new_set;
2912 sigset_t new_blocked;
2914 old_set = current->blocked.sig[0];
2917 if (copy_from_user(&new_set, nset, sizeof(*nset)))
2919 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2921 new_blocked = current->blocked;
2925 sigaddsetmask(&new_blocked, new_set);
2928 sigdelsetmask(&new_blocked, new_set);
2931 new_blocked.sig[0] = new_set;
2937 set_current_blocked(&new_blocked);
2941 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2947 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2949 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2951 * sys_rt_sigaction - alter an action taken by a process
2952 * @sig: signal to be sent
2953 * @act: new sigaction
2954 * @oact: used to save the previous sigaction
2955 * @sigsetsize: size of sigset_t type
2957 SYSCALL_DEFINE4(rt_sigaction, int, sig,
2958 const struct sigaction __user *, act,
2959 struct sigaction __user *, oact,
2962 struct k_sigaction new_sa, old_sa;
2965 /* XXX: Don't preclude handling different sized sigset_t's. */
2966 if (sigsetsize != sizeof(sigset_t))
2970 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2974 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2977 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2983 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2985 #ifdef __ARCH_WANT_SYS_SGETMASK
2988 * For backwards compatibility. Functionality superseded by sigprocmask.
2990 SYSCALL_DEFINE0(sgetmask)
2993 return current->blocked.sig[0];
2996 SYSCALL_DEFINE1(ssetmask, int, newmask)
3000 spin_lock_irq(¤t->sighand->siglock);
3001 old = current->blocked.sig[0];
3003 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
3005 recalc_sigpending();
3006 spin_unlock_irq(¤t->sighand->siglock);
3010 #endif /* __ARCH_WANT_SGETMASK */
3012 #ifdef __ARCH_WANT_SYS_SIGNAL
3014 * For backwards compatibility. Functionality superseded by sigaction.
3016 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3018 struct k_sigaction new_sa, old_sa;
3021 new_sa.sa.sa_handler = handler;
3022 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3023 sigemptyset(&new_sa.sa.sa_mask);
3025 ret = do_sigaction(sig, &new_sa, &old_sa);
3027 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3029 #endif /* __ARCH_WANT_SYS_SIGNAL */
3031 #ifdef __ARCH_WANT_SYS_PAUSE
3033 SYSCALL_DEFINE0(pause)
3035 while (!signal_pending(current)) {
3036 current->state = TASK_INTERRUPTIBLE;
3039 return -ERESTARTNOHAND;
3044 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3046 * sys_rt_sigsuspend - replace the signal mask for a value with the
3047 * @unewset value until a signal is received
3048 * @unewset: new signal mask value
3049 * @sigsetsize: size of sigset_t type
3051 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3055 /* XXX: Don't preclude handling different sized sigset_t's. */
3056 if (sigsetsize != sizeof(sigset_t))
3059 if (copy_from_user(&newset, unewset, sizeof(newset)))
3061 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
3063 spin_lock_irq(¤t->sighand->siglock);
3064 current->saved_sigmask = current->blocked;
3065 current->blocked = newset;
3066 recalc_sigpending();
3067 spin_unlock_irq(¤t->sighand->siglock);
3069 current->state = TASK_INTERRUPTIBLE;
3071 set_restore_sigmask();
3072 return -ERESTARTNOHAND;
3074 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3076 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3081 void __init signals_init(void)
3083 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3086 #ifdef CONFIG_KGDB_KDB
3087 #include <linux/kdb.h>
3089 * kdb_send_sig_info - Allows kdb to send signals without exposing
3090 * signal internals. This function checks if the required locks are
3091 * available before calling the main signal code, to avoid kdb
3095 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3097 static struct task_struct *kdb_prev_t;
3099 if (!spin_trylock(&t->sighand->siglock)) {
3100 kdb_printf("Can't do kill command now.\n"
3101 "The sigmask lock is held somewhere else in "
3102 "kernel, try again later\n");
3105 spin_unlock(&t->sighand->siglock);
3106 new_t = kdb_prev_t != t;
3108 if (t->state != TASK_RUNNING && new_t) {
3109 kdb_printf("Process is not RUNNING, sending a signal from "
3110 "kdb risks deadlock\n"
3111 "on the run queue locks. "
3112 "The signal has _not_ been sent.\n"
3113 "Reissue the kill command if you want to risk "
3117 sig = info->si_signo;
3118 if (send_sig_info(sig, info, t))
3119 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3122 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3124 #endif /* CONFIG_KGDB_KDB */