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.
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 (!recalc_sigpending_tsk(current) && !freezing(current))
154 clear_thread_flag(TIF_SIGPENDING);
158 /* Given the mask, find the first available signal that should be serviced. */
160 #define SYNCHRONOUS_MASK \
161 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
162 sigmask(SIGTRAP) | sigmask(SIGFPE))
164 int next_signal(struct sigpending *pending, sigset_t *mask)
166 unsigned long i, *s, *m, x;
169 s = pending->signal.sig;
173 * Handle the first word specially: it contains the
174 * synchronous signals that need to be dequeued first.
178 if (x & SYNCHRONOUS_MASK)
179 x &= SYNCHRONOUS_MASK;
184 switch (_NSIG_WORDS) {
186 for (i = 1; i < _NSIG_WORDS; ++i) {
190 sig = ffz(~x) + i*_NSIG_BPW + 1;
199 sig = ffz(~x) + _NSIG_BPW + 1;
210 static inline void print_dropped_signal(int sig)
212 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
214 if (!print_fatal_signals)
217 if (!__ratelimit(&ratelimit_state))
220 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
221 current->comm, current->pid, sig);
225 * task_set_jobctl_pending - set jobctl pending bits
227 * @mask: pending bits to set
229 * Clear @mask from @task->jobctl. @mask must be subset of
230 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
231 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
232 * cleared. If @task is already being killed or exiting, this function
236 * Must be called with @task->sighand->siglock held.
239 * %true if @mask is set, %false if made noop because @task was dying.
241 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
243 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
244 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
245 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
247 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
250 if (mask & JOBCTL_STOP_SIGMASK)
251 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
253 task->jobctl |= mask;
258 * task_clear_jobctl_trapping - clear jobctl trapping bit
261 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
262 * Clear it and wake up the ptracer. Note that we don't need any further
263 * locking. @task->siglock guarantees that @task->parent points to the
267 * Must be called with @task->sighand->siglock held.
269 void task_clear_jobctl_trapping(struct task_struct *task)
271 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
272 task->jobctl &= ~JOBCTL_TRAPPING;
273 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
278 * task_clear_jobctl_pending - clear jobctl pending bits
280 * @mask: pending bits to clear
282 * Clear @mask from @task->jobctl. @mask must be subset of
283 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
284 * STOP bits are cleared together.
286 * If clearing of @mask leaves no stop or trap pending, this function calls
287 * task_clear_jobctl_trapping().
290 * Must be called with @task->sighand->siglock held.
292 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
294 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
296 if (mask & JOBCTL_STOP_PENDING)
297 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
299 task->jobctl &= ~mask;
301 if (!(task->jobctl & JOBCTL_PENDING_MASK))
302 task_clear_jobctl_trapping(task);
306 * task_participate_group_stop - participate in a group stop
307 * @task: task participating in a group stop
309 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
310 * Group stop states are cleared and the group stop count is consumed if
311 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
312 * stop, the appropriate %SIGNAL_* flags are set.
315 * Must be called with @task->sighand->siglock held.
318 * %true if group stop completion should be notified to the parent, %false
321 static bool task_participate_group_stop(struct task_struct *task)
323 struct signal_struct *sig = task->signal;
324 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
326 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
328 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
333 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
334 sig->group_stop_count--;
337 * Tell the caller to notify completion iff we are entering into a
338 * fresh group stop. Read comment in do_signal_stop() for details.
340 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
341 sig->flags = SIGNAL_STOP_STOPPED;
348 * allocate a new signal queue record
349 * - this may be called without locks if and only if t == current, otherwise an
350 * appropriate lock must be held to stop the target task from exiting
352 static struct sigqueue *
353 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
355 struct sigqueue *q = NULL;
356 struct user_struct *user;
359 * Protect access to @t credentials. This can go away when all
360 * callers hold rcu read lock.
363 user = get_uid(__task_cred(t)->user);
364 atomic_inc(&user->sigpending);
367 if (override_rlimit ||
368 atomic_read(&user->sigpending) <=
369 task_rlimit(t, RLIMIT_SIGPENDING)) {
370 q = kmem_cache_alloc(sigqueue_cachep, flags);
372 print_dropped_signal(sig);
375 if (unlikely(q == NULL)) {
376 atomic_dec(&user->sigpending);
379 INIT_LIST_HEAD(&q->list);
387 static void __sigqueue_free(struct sigqueue *q)
389 if (q->flags & SIGQUEUE_PREALLOC)
391 atomic_dec(&q->user->sigpending);
393 kmem_cache_free(sigqueue_cachep, q);
396 void flush_sigqueue(struct sigpending *queue)
400 sigemptyset(&queue->signal);
401 while (!list_empty(&queue->list)) {
402 q = list_entry(queue->list.next, struct sigqueue , list);
403 list_del_init(&q->list);
409 * Flush all pending signals for a task.
411 void __flush_signals(struct task_struct *t)
413 clear_tsk_thread_flag(t, TIF_SIGPENDING);
414 flush_sigqueue(&t->pending);
415 flush_sigqueue(&t->signal->shared_pending);
418 void flush_signals(struct task_struct *t)
422 spin_lock_irqsave(&t->sighand->siglock, flags);
424 spin_unlock_irqrestore(&t->sighand->siglock, flags);
427 static void __flush_itimer_signals(struct sigpending *pending)
429 sigset_t signal, retain;
430 struct sigqueue *q, *n;
432 signal = pending->signal;
433 sigemptyset(&retain);
435 list_for_each_entry_safe(q, n, &pending->list, list) {
436 int sig = q->info.si_signo;
438 if (likely(q->info.si_code != SI_TIMER)) {
439 sigaddset(&retain, sig);
441 sigdelset(&signal, sig);
442 list_del_init(&q->list);
447 sigorsets(&pending->signal, &signal, &retain);
450 void flush_itimer_signals(void)
452 struct task_struct *tsk = current;
455 spin_lock_irqsave(&tsk->sighand->siglock, flags);
456 __flush_itimer_signals(&tsk->pending);
457 __flush_itimer_signals(&tsk->signal->shared_pending);
458 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
461 void ignore_signals(struct task_struct *t)
465 for (i = 0; i < _NSIG; ++i)
466 t->sighand->action[i].sa.sa_handler = SIG_IGN;
472 * Flush all handlers for a task.
476 flush_signal_handlers(struct task_struct *t, int force_default)
479 struct k_sigaction *ka = &t->sighand->action[0];
480 for (i = _NSIG ; i != 0 ; i--) {
481 if (force_default || ka->sa.sa_handler != SIG_IGN)
482 ka->sa.sa_handler = SIG_DFL;
484 sigemptyset(&ka->sa.sa_mask);
489 int unhandled_signal(struct task_struct *tsk, int sig)
491 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
492 if (is_global_init(tsk))
494 if (handler != SIG_IGN && handler != SIG_DFL)
496 /* if ptraced, let the tracer determine */
501 * Notify the system that a driver wants to block all signals for this
502 * process, and wants to be notified if any signals at all were to be
503 * sent/acted upon. If the notifier routine returns non-zero, then the
504 * signal will be acted upon after all. If the notifier routine returns 0,
505 * then then signal will be blocked. Only one block per process is
506 * allowed. priv is a pointer to private data that the notifier routine
507 * can use to determine if the signal should be blocked or not.
510 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
514 spin_lock_irqsave(¤t->sighand->siglock, flags);
515 current->notifier_mask = mask;
516 current->notifier_data = priv;
517 current->notifier = notifier;
518 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
521 /* Notify the system that blocking has ended. */
524 unblock_all_signals(void)
528 spin_lock_irqsave(¤t->sighand->siglock, flags);
529 current->notifier = NULL;
530 current->notifier_data = NULL;
532 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
535 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
537 struct sigqueue *q, *first = NULL;
540 * Collect the siginfo appropriate to this signal. Check if
541 * there is another siginfo for the same signal.
543 list_for_each_entry(q, &list->list, list) {
544 if (q->info.si_signo == sig) {
551 sigdelset(&list->signal, sig);
555 list_del_init(&first->list);
556 copy_siginfo(info, &first->info);
557 __sigqueue_free(first);
560 * Ok, it wasn't in the queue. This must be
561 * a fast-pathed signal or we must have been
562 * out of queue space. So zero out the info.
564 info->si_signo = sig;
566 info->si_code = SI_USER;
572 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
575 int sig = next_signal(pending, mask);
578 if (current->notifier) {
579 if (sigismember(current->notifier_mask, sig)) {
580 if (!(current->notifier)(current->notifier_data)) {
581 clear_thread_flag(TIF_SIGPENDING);
587 collect_signal(sig, pending, info);
594 * Dequeue a signal and return the element to the caller, which is
595 * expected to free it.
597 * All callers have to hold the siglock.
599 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
603 /* We only dequeue private signals from ourselves, we don't let
604 * signalfd steal them
606 signr = __dequeue_signal(&tsk->pending, mask, info);
608 signr = __dequeue_signal(&tsk->signal->shared_pending,
613 * itimers are process shared and we restart periodic
614 * itimers in the signal delivery path to prevent DoS
615 * attacks in the high resolution timer case. This is
616 * compliant with the old way of self-restarting
617 * itimers, as the SIGALRM is a legacy signal and only
618 * queued once. Changing the restart behaviour to
619 * restart the timer in the signal dequeue path is
620 * reducing the timer noise on heavy loaded !highres
623 if (unlikely(signr == SIGALRM)) {
624 struct hrtimer *tmr = &tsk->signal->real_timer;
626 if (!hrtimer_is_queued(tmr) &&
627 tsk->signal->it_real_incr.tv64 != 0) {
628 hrtimer_forward(tmr, tmr->base->get_time(),
629 tsk->signal->it_real_incr);
630 hrtimer_restart(tmr);
639 if (unlikely(sig_kernel_stop(signr))) {
641 * Set a marker that we have dequeued a stop signal. Our
642 * caller might release the siglock and then the pending
643 * stop signal it is about to process is no longer in the
644 * pending bitmasks, but must still be cleared by a SIGCONT
645 * (and overruled by a SIGKILL). So those cases clear this
646 * shared flag after we've set it. Note that this flag may
647 * remain set after the signal we return is ignored or
648 * handled. That doesn't matter because its only purpose
649 * is to alert stop-signal processing code when another
650 * processor has come along and cleared the flag.
652 current->jobctl |= JOBCTL_STOP_DEQUEUED;
654 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
656 * Release the siglock to ensure proper locking order
657 * of timer locks outside of siglocks. Note, we leave
658 * irqs disabled here, since the posix-timers code is
659 * about to disable them again anyway.
661 spin_unlock(&tsk->sighand->siglock);
662 do_schedule_next_timer(info);
663 spin_lock(&tsk->sighand->siglock);
669 * Tell a process that it has a new active signal..
671 * NOTE! we rely on the previous spin_lock to
672 * lock interrupts for us! We can only be called with
673 * "siglock" held, and the local interrupt must
674 * have been disabled when that got acquired!
676 * No need to set need_resched since signal event passing
677 * goes through ->blocked
679 void signal_wake_up(struct task_struct *t, int resume)
683 set_tsk_thread_flag(t, TIF_SIGPENDING);
686 * For SIGKILL, we want to wake it up in the stopped/traced/killable
687 * case. We don't check t->state here because there is a race with it
688 * executing another processor and just now entering stopped state.
689 * By using wake_up_state, we ensure the process will wake up and
690 * handle its death signal.
692 mask = TASK_INTERRUPTIBLE;
694 mask |= TASK_WAKEKILL;
695 if (!wake_up_state(t, mask))
700 * Remove signals in mask from the pending set and queue.
701 * Returns 1 if any signals were found.
703 * All callers must be holding the siglock.
705 * This version takes a sigset mask and looks at all signals,
706 * not just those in the first mask word.
708 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
710 struct sigqueue *q, *n;
713 sigandsets(&m, mask, &s->signal);
714 if (sigisemptyset(&m))
717 sigandnsets(&s->signal, &s->signal, mask);
718 list_for_each_entry_safe(q, n, &s->list, list) {
719 if (sigismember(mask, q->info.si_signo)) {
720 list_del_init(&q->list);
727 * Remove signals in mask from the pending set and queue.
728 * Returns 1 if any signals were found.
730 * All callers must be holding the siglock.
732 static int rm_from_queue(unsigned long mask, struct sigpending *s)
734 struct sigqueue *q, *n;
736 if (!sigtestsetmask(&s->signal, mask))
739 sigdelsetmask(&s->signal, mask);
740 list_for_each_entry_safe(q, n, &s->list, list) {
741 if (q->info.si_signo < SIGRTMIN &&
742 (mask & sigmask(q->info.si_signo))) {
743 list_del_init(&q->list);
750 static inline int is_si_special(const struct siginfo *info)
752 return info <= SEND_SIG_FORCED;
755 static inline bool si_fromuser(const struct siginfo *info)
757 return info == SEND_SIG_NOINFO ||
758 (!is_si_special(info) && SI_FROMUSER(info));
762 * called with RCU read lock from check_kill_permission()
764 static int kill_ok_by_cred(struct task_struct *t)
766 const struct cred *cred = current_cred();
767 const struct cred *tcred = __task_cred(t);
769 if (cred->user->user_ns == tcred->user->user_ns &&
770 (cred->euid == tcred->suid ||
771 cred->euid == tcred->uid ||
772 cred->uid == tcred->suid ||
773 cred->uid == tcred->uid))
776 if (ns_capable(tcred->user->user_ns, CAP_KILL))
783 * Bad permissions for sending the signal
784 * - the caller must hold the RCU read lock
786 static int check_kill_permission(int sig, struct siginfo *info,
787 struct task_struct *t)
792 if (!valid_signal(sig))
795 if (!si_fromuser(info))
798 error = audit_signal_info(sig, t); /* Let audit system see the signal */
802 if (!same_thread_group(current, t) &&
803 !kill_ok_by_cred(t)) {
806 sid = task_session(t);
808 * We don't return the error if sid == NULL. The
809 * task was unhashed, the caller must notice this.
811 if (!sid || sid == task_session(current))
818 return security_task_kill(t, info, sig, 0);
822 * ptrace_trap_notify - schedule trap to notify ptracer
823 * @t: tracee wanting to notify tracer
825 * This function schedules sticky ptrace trap which is cleared on the next
826 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
829 * If @t is running, STOP trap will be taken. If trapped for STOP and
830 * ptracer is listening for events, tracee is woken up so that it can
831 * re-trap for the new event. If trapped otherwise, STOP trap will be
832 * eventually taken without returning to userland after the existing traps
833 * are finished by PTRACE_CONT.
836 * Must be called with @task->sighand->siglock held.
838 static void ptrace_trap_notify(struct task_struct *t)
840 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
841 assert_spin_locked(&t->sighand->siglock);
843 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
844 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
848 * Handle magic process-wide effects of stop/continue signals. Unlike
849 * the signal actions, these happen immediately at signal-generation
850 * time regardless of blocking, ignoring, or handling. This does the
851 * actual continuing for SIGCONT, but not the actual stopping for stop
852 * signals. The process stop is done as a signal action for SIG_DFL.
854 * Returns true if the signal should be actually delivered, otherwise
855 * it should be dropped.
857 static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
859 struct signal_struct *signal = p->signal;
860 struct task_struct *t;
862 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
864 * The process is in the middle of dying, nothing to do.
866 } else if (sig_kernel_stop(sig)) {
868 * This is a stop signal. Remove SIGCONT from all queues.
870 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
873 rm_from_queue(sigmask(SIGCONT), &t->pending);
874 } while_each_thread(p, t);
875 } else if (sig == SIGCONT) {
878 * Remove all stop signals from all queues, wake all threads.
880 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
883 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
884 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
885 if (likely(!(t->ptrace & PT_SEIZED)))
886 wake_up_state(t, __TASK_STOPPED);
888 ptrace_trap_notify(t);
889 } while_each_thread(p, t);
892 * Notify the parent with CLD_CONTINUED if we were stopped.
894 * If we were in the middle of a group stop, we pretend it
895 * was already finished, and then continued. Since SIGCHLD
896 * doesn't queue we report only CLD_STOPPED, as if the next
897 * CLD_CONTINUED was dropped.
900 if (signal->flags & SIGNAL_STOP_STOPPED)
901 why |= SIGNAL_CLD_CONTINUED;
902 else if (signal->group_stop_count)
903 why |= SIGNAL_CLD_STOPPED;
907 * The first thread which returns from do_signal_stop()
908 * will take ->siglock, notice SIGNAL_CLD_MASK, and
909 * notify its parent. See get_signal_to_deliver().
911 signal->flags = why | SIGNAL_STOP_CONTINUED;
912 signal->group_stop_count = 0;
913 signal->group_exit_code = 0;
917 return !sig_ignored(p, sig, from_ancestor_ns);
921 * Test if P wants to take SIG. After we've checked all threads with this,
922 * it's equivalent to finding no threads not blocking SIG. Any threads not
923 * blocking SIG were ruled out because they are not running and already
924 * have pending signals. Such threads will dequeue from the shared queue
925 * as soon as they're available, so putting the signal on the shared queue
926 * will be equivalent to sending it to one such thread.
928 static inline int wants_signal(int sig, struct task_struct *p)
930 if (sigismember(&p->blocked, sig))
932 if (p->flags & PF_EXITING)
936 if (task_is_stopped_or_traced(p))
938 return task_curr(p) || !signal_pending(p);
941 static void complete_signal(int sig, struct task_struct *p, int group)
943 struct signal_struct *signal = p->signal;
944 struct task_struct *t;
947 * Now find a thread we can wake up to take the signal off the queue.
949 * If the main thread wants the signal, it gets first crack.
950 * Probably the least surprising to the average bear.
952 if (wants_signal(sig, p))
954 else if (!group || thread_group_empty(p))
956 * There is just one thread and it does not need to be woken.
957 * It will dequeue unblocked signals before it runs again.
962 * Otherwise try to find a suitable thread.
964 t = signal->curr_target;
965 while (!wants_signal(sig, t)) {
967 if (t == signal->curr_target)
969 * No thread needs to be woken.
970 * Any eligible threads will see
971 * the signal in the queue soon.
975 signal->curr_target = t;
979 * Found a killable thread. If the signal will be fatal,
980 * then start taking the whole group down immediately.
982 if (sig_fatal(p, sig) &&
983 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
984 !sigismember(&t->real_blocked, sig) &&
985 (sig == SIGKILL || !t->ptrace)) {
987 * This signal will be fatal to the whole group.
989 if (!sig_kernel_coredump(sig)) {
991 * Start a group exit and wake everybody up.
992 * This way we don't have other threads
993 * running and doing things after a slower
994 * thread has the fatal signal pending.
996 signal->flags = SIGNAL_GROUP_EXIT;
997 signal->group_exit_code = sig;
998 signal->group_stop_count = 0;
1001 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1002 sigaddset(&t->pending.signal, SIGKILL);
1003 signal_wake_up(t, 1);
1004 } while_each_thread(p, t);
1010 * The signal is already in the shared-pending queue.
1011 * Tell the chosen thread to wake up and dequeue it.
1013 signal_wake_up(t, sig == SIGKILL);
1017 static inline int legacy_queue(struct sigpending *signals, int sig)
1019 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1022 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1023 int group, int from_ancestor_ns)
1025 struct sigpending *pending;
1027 int override_rlimit;
1029 trace_signal_generate(sig, info, t);
1031 assert_spin_locked(&t->sighand->siglock);
1033 if (!prepare_signal(sig, t, from_ancestor_ns))
1036 pending = group ? &t->signal->shared_pending : &t->pending;
1038 * Short-circuit ignored signals and support queuing
1039 * exactly one non-rt signal, so that we can get more
1040 * detailed information about the cause of the signal.
1042 if (legacy_queue(pending, sig))
1045 * fast-pathed signals for kernel-internal things like SIGSTOP
1048 if (info == SEND_SIG_FORCED)
1052 * Real-time signals must be queued if sent by sigqueue, or
1053 * some other real-time mechanism. It is implementation
1054 * defined whether kill() does so. We attempt to do so, on
1055 * the principle of least surprise, but since kill is not
1056 * allowed to fail with EAGAIN when low on memory we just
1057 * make sure at least one signal gets delivered and don't
1058 * pass on the info struct.
1061 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1063 override_rlimit = 0;
1065 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1068 list_add_tail(&q->list, &pending->list);
1069 switch ((unsigned long) info) {
1070 case (unsigned long) SEND_SIG_NOINFO:
1071 q->info.si_signo = sig;
1072 q->info.si_errno = 0;
1073 q->info.si_code = SI_USER;
1074 q->info.si_pid = task_tgid_nr_ns(current,
1075 task_active_pid_ns(t));
1076 q->info.si_uid = current_uid();
1078 case (unsigned long) SEND_SIG_PRIV:
1079 q->info.si_signo = sig;
1080 q->info.si_errno = 0;
1081 q->info.si_code = SI_KERNEL;
1086 copy_siginfo(&q->info, info);
1087 if (from_ancestor_ns)
1091 } else if (!is_si_special(info)) {
1092 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1094 * Queue overflow, abort. We may abort if the
1095 * signal was rt and sent by user using something
1096 * other than kill().
1098 trace_signal_overflow_fail(sig, group, info);
1102 * This is a silent loss of information. We still
1103 * send the signal, but the *info bits are lost.
1105 trace_signal_lose_info(sig, group, info);
1110 signalfd_notify(t, sig);
1111 sigaddset(&pending->signal, sig);
1112 complete_signal(sig, t, group);
1116 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1119 int from_ancestor_ns = 0;
1121 #ifdef CONFIG_PID_NS
1122 from_ancestor_ns = si_fromuser(info) &&
1123 !task_pid_nr_ns(current, task_active_pid_ns(t));
1126 return __send_signal(sig, info, t, group, from_ancestor_ns);
1129 static void print_fatal_signal(struct pt_regs *regs, int signr)
1131 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1132 current->comm, task_pid_nr(current), signr);
1134 #if defined(__i386__) && !defined(__arch_um__)
1135 printk("code at %08lx: ", regs->ip);
1138 for (i = 0; i < 16; i++) {
1141 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1143 printk("%02x ", insn);
1153 static int __init setup_print_fatal_signals(char *str)
1155 get_option (&str, &print_fatal_signals);
1160 __setup("print-fatal-signals=", setup_print_fatal_signals);
1163 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1165 return send_signal(sig, info, p, 1);
1169 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1171 return send_signal(sig, info, t, 0);
1174 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1177 unsigned long flags;
1180 if (lock_task_sighand(p, &flags)) {
1181 ret = send_signal(sig, info, p, group);
1182 unlock_task_sighand(p, &flags);
1189 * Force a signal that the process can't ignore: if necessary
1190 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1192 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1193 * since we do not want to have a signal handler that was blocked
1194 * be invoked when user space had explicitly blocked it.
1196 * We don't want to have recursive SIGSEGV's etc, for example,
1197 * that is why we also clear SIGNAL_UNKILLABLE.
1200 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1202 unsigned long int flags;
1203 int ret, blocked, ignored;
1204 struct k_sigaction *action;
1206 spin_lock_irqsave(&t->sighand->siglock, flags);
1207 action = &t->sighand->action[sig-1];
1208 ignored = action->sa.sa_handler == SIG_IGN;
1209 blocked = sigismember(&t->blocked, sig);
1210 if (blocked || ignored) {
1211 action->sa.sa_handler = SIG_DFL;
1213 sigdelset(&t->blocked, sig);
1214 recalc_sigpending_and_wake(t);
1217 if (action->sa.sa_handler == SIG_DFL)
1218 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1219 ret = specific_send_sig_info(sig, info, t);
1220 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1226 * Nuke all other threads in the group.
1228 int zap_other_threads(struct task_struct *p)
1230 struct task_struct *t = p;
1233 p->signal->group_stop_count = 0;
1235 while_each_thread(p, t) {
1236 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1239 /* Don't bother with already dead threads */
1242 sigaddset(&t->pending.signal, SIGKILL);
1243 signal_wake_up(t, 1);
1249 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1250 unsigned long *flags)
1252 struct sighand_struct *sighand;
1256 sighand = rcu_dereference(tsk->sighand);
1257 if (unlikely(sighand == NULL))
1260 spin_lock_irqsave(&sighand->siglock, *flags);
1261 if (likely(sighand == tsk->sighand))
1263 spin_unlock_irqrestore(&sighand->siglock, *flags);
1271 * send signal info to all the members of a group
1273 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1278 ret = check_kill_permission(sig, info, p);
1282 ret = do_send_sig_info(sig, info, p, true);
1288 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1289 * control characters do (^C, ^Z etc)
1290 * - the caller must hold at least a readlock on tasklist_lock
1292 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1294 struct task_struct *p = NULL;
1295 int retval, success;
1299 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1300 int err = group_send_sig_info(sig, info, p);
1303 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1304 return success ? 0 : retval;
1307 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1310 struct task_struct *p;
1314 p = pid_task(pid, PIDTYPE_PID);
1316 error = group_send_sig_info(sig, info, p);
1317 if (unlikely(error == -ESRCH))
1319 * The task was unhashed in between, try again.
1320 * If it is dead, pid_task() will return NULL,
1321 * if we race with de_thread() it will find the
1331 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1335 error = kill_pid_info(sig, info, find_vpid(pid));
1340 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1341 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1342 uid_t uid, uid_t euid, u32 secid)
1345 struct task_struct *p;
1346 const struct cred *pcred;
1347 unsigned long flags;
1349 if (!valid_signal(sig))
1353 p = pid_task(pid, PIDTYPE_PID);
1358 pcred = __task_cred(p);
1359 if (si_fromuser(info) &&
1360 euid != pcred->suid && euid != pcred->uid &&
1361 uid != pcred->suid && uid != pcred->uid) {
1365 ret = security_task_kill(p, info, sig, secid);
1370 if (lock_task_sighand(p, &flags)) {
1371 ret = __send_signal(sig, info, p, 1, 0);
1372 unlock_task_sighand(p, &flags);
1380 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1383 * kill_something_info() interprets pid in interesting ways just like kill(2).
1385 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1386 * is probably wrong. Should make it like BSD or SYSV.
1389 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1395 ret = kill_pid_info(sig, info, find_vpid(pid));
1400 read_lock(&tasklist_lock);
1402 ret = __kill_pgrp_info(sig, info,
1403 pid ? find_vpid(-pid) : task_pgrp(current));
1405 int retval = 0, count = 0;
1406 struct task_struct * p;
1408 for_each_process(p) {
1409 if (task_pid_vnr(p) > 1 &&
1410 !same_thread_group(p, current)) {
1411 int err = group_send_sig_info(sig, info, p);
1417 ret = count ? retval : -ESRCH;
1419 read_unlock(&tasklist_lock);
1425 * These are for backward compatibility with the rest of the kernel source.
1428 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1431 * Make sure legacy kernel users don't send in bad values
1432 * (normal paths check this in check_kill_permission).
1434 if (!valid_signal(sig))
1437 return do_send_sig_info(sig, info, p, false);
1440 #define __si_special(priv) \
1441 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1444 send_sig(int sig, struct task_struct *p, int priv)
1446 return send_sig_info(sig, __si_special(priv), p);
1450 force_sig(int sig, struct task_struct *p)
1452 force_sig_info(sig, SEND_SIG_PRIV, p);
1456 * When things go south during signal handling, we
1457 * will force a SIGSEGV. And if the signal that caused
1458 * the problem was already a SIGSEGV, we'll want to
1459 * make sure we don't even try to deliver the signal..
1462 force_sigsegv(int sig, struct task_struct *p)
1464 if (sig == SIGSEGV) {
1465 unsigned long flags;
1466 spin_lock_irqsave(&p->sighand->siglock, flags);
1467 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1468 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1470 force_sig(SIGSEGV, p);
1474 int kill_pgrp(struct pid *pid, int sig, int priv)
1478 read_lock(&tasklist_lock);
1479 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1480 read_unlock(&tasklist_lock);
1484 EXPORT_SYMBOL(kill_pgrp);
1486 int kill_pid(struct pid *pid, int sig, int priv)
1488 return kill_pid_info(sig, __si_special(priv), pid);
1490 EXPORT_SYMBOL(kill_pid);
1493 * These functions support sending signals using preallocated sigqueue
1494 * structures. This is needed "because realtime applications cannot
1495 * afford to lose notifications of asynchronous events, like timer
1496 * expirations or I/O completions". In the case of POSIX Timers
1497 * we allocate the sigqueue structure from the timer_create. If this
1498 * allocation fails we are able to report the failure to the application
1499 * with an EAGAIN error.
1501 struct sigqueue *sigqueue_alloc(void)
1503 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1506 q->flags |= SIGQUEUE_PREALLOC;
1511 void sigqueue_free(struct sigqueue *q)
1513 unsigned long flags;
1514 spinlock_t *lock = ¤t->sighand->siglock;
1516 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1518 * We must hold ->siglock while testing q->list
1519 * to serialize with collect_signal() or with
1520 * __exit_signal()->flush_sigqueue().
1522 spin_lock_irqsave(lock, flags);
1523 q->flags &= ~SIGQUEUE_PREALLOC;
1525 * If it is queued it will be freed when dequeued,
1526 * like the "regular" sigqueue.
1528 if (!list_empty(&q->list))
1530 spin_unlock_irqrestore(lock, flags);
1536 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1538 int sig = q->info.si_signo;
1539 struct sigpending *pending;
1540 unsigned long flags;
1543 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1546 if (!likely(lock_task_sighand(t, &flags)))
1549 ret = 1; /* the signal is ignored */
1550 if (!prepare_signal(sig, t, 0))
1554 if (unlikely(!list_empty(&q->list))) {
1556 * If an SI_TIMER entry is already queue just increment
1557 * the overrun count.
1559 BUG_ON(q->info.si_code != SI_TIMER);
1560 q->info.si_overrun++;
1563 q->info.si_overrun = 0;
1565 signalfd_notify(t, sig);
1566 pending = group ? &t->signal->shared_pending : &t->pending;
1567 list_add_tail(&q->list, &pending->list);
1568 sigaddset(&pending->signal, sig);
1569 complete_signal(sig, t, group);
1571 unlock_task_sighand(t, &flags);
1577 * Let a parent know about the death of a child.
1578 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1580 * Returns true if our parent ignored us and so we've switched to
1583 bool do_notify_parent(struct task_struct *tsk, int sig)
1585 struct siginfo info;
1586 unsigned long flags;
1587 struct sighand_struct *psig;
1588 bool autoreap = false;
1592 /* do_notify_parent_cldstop should have been called instead. */
1593 BUG_ON(task_is_stopped_or_traced(tsk));
1595 BUG_ON(!tsk->ptrace &&
1596 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1598 info.si_signo = sig;
1601 * we are under tasklist_lock here so our parent is tied to
1602 * us and cannot exit and release its namespace.
1604 * the only it can is to switch its nsproxy with sys_unshare,
1605 * bu uncharing pid namespaces is not allowed, so we'll always
1606 * see relevant namespace
1608 * write_lock() currently calls preempt_disable() which is the
1609 * same as rcu_read_lock(), but according to Oleg, this is not
1610 * correct to rely on this
1613 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1614 info.si_uid = __task_cred(tsk)->uid;
1617 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1618 tsk->signal->utime));
1619 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1620 tsk->signal->stime));
1622 info.si_status = tsk->exit_code & 0x7f;
1623 if (tsk->exit_code & 0x80)
1624 info.si_code = CLD_DUMPED;
1625 else if (tsk->exit_code & 0x7f)
1626 info.si_code = CLD_KILLED;
1628 info.si_code = CLD_EXITED;
1629 info.si_status = tsk->exit_code >> 8;
1632 psig = tsk->parent->sighand;
1633 spin_lock_irqsave(&psig->siglock, flags);
1634 if (!tsk->ptrace && sig == SIGCHLD &&
1635 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1636 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1638 * We are exiting and our parent doesn't care. POSIX.1
1639 * defines special semantics for setting SIGCHLD to SIG_IGN
1640 * or setting the SA_NOCLDWAIT flag: we should be reaped
1641 * automatically and not left for our parent's wait4 call.
1642 * Rather than having the parent do it as a magic kind of
1643 * signal handler, we just set this to tell do_exit that we
1644 * can be cleaned up without becoming a zombie. Note that
1645 * we still call __wake_up_parent in this case, because a
1646 * blocked sys_wait4 might now return -ECHILD.
1648 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1649 * is implementation-defined: we do (if you don't want
1650 * it, just use SIG_IGN instead).
1653 tsk->exit_signal = -1;
1654 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1657 if (valid_signal(sig) && sig)
1658 __group_send_sig_info(sig, &info, tsk->parent);
1659 __wake_up_parent(tsk, tsk->parent);
1660 spin_unlock_irqrestore(&psig->siglock, flags);
1666 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1667 * @tsk: task reporting the state change
1668 * @for_ptracer: the notification is for ptracer
1669 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1671 * Notify @tsk's parent that the stopped/continued state has changed. If
1672 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1673 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1676 * Must be called with tasklist_lock at least read locked.
1678 static void do_notify_parent_cldstop(struct task_struct *tsk,
1679 bool for_ptracer, int why)
1681 struct siginfo info;
1682 unsigned long flags;
1683 struct task_struct *parent;
1684 struct sighand_struct *sighand;
1687 parent = tsk->parent;
1689 tsk = tsk->group_leader;
1690 parent = tsk->real_parent;
1693 info.si_signo = SIGCHLD;
1696 * see comment in do_notify_parent() about the following 4 lines
1699 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1700 info.si_uid = __task_cred(tsk)->uid;
1703 info.si_utime = cputime_to_clock_t(tsk->utime);
1704 info.si_stime = cputime_to_clock_t(tsk->stime);
1709 info.si_status = SIGCONT;
1712 info.si_status = tsk->signal->group_exit_code & 0x7f;
1715 info.si_status = tsk->exit_code & 0x7f;
1721 sighand = parent->sighand;
1722 spin_lock_irqsave(&sighand->siglock, flags);
1723 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1724 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1725 __group_send_sig_info(SIGCHLD, &info, parent);
1727 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1729 __wake_up_parent(tsk, parent);
1730 spin_unlock_irqrestore(&sighand->siglock, flags);
1733 static inline int may_ptrace_stop(void)
1735 if (!likely(current->ptrace))
1738 * Are we in the middle of do_coredump?
1739 * If so and our tracer is also part of the coredump stopping
1740 * is a deadlock situation, and pointless because our tracer
1741 * is dead so don't allow us to stop.
1742 * If SIGKILL was already sent before the caller unlocked
1743 * ->siglock we must see ->core_state != NULL. Otherwise it
1744 * is safe to enter schedule().
1746 if (unlikely(current->mm->core_state) &&
1747 unlikely(current->mm == current->parent->mm))
1754 * Return non-zero if there is a SIGKILL that should be waking us up.
1755 * Called with the siglock held.
1757 static int sigkill_pending(struct task_struct *tsk)
1759 return sigismember(&tsk->pending.signal, SIGKILL) ||
1760 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1764 * Test whether the target task of the usual cldstop notification - the
1765 * real_parent of @child - is in the same group as the ptracer.
1767 static bool real_parent_is_ptracer(struct task_struct *child)
1769 return same_thread_group(child->parent, child->real_parent);
1773 * This must be called with current->sighand->siglock held.
1775 * This should be the path for all ptrace stops.
1776 * We always set current->last_siginfo while stopped here.
1777 * That makes it a way to test a stopped process for
1778 * being ptrace-stopped vs being job-control-stopped.
1780 * If we actually decide not to stop at all because the tracer
1781 * is gone, we keep current->exit_code unless clear_code.
1783 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1784 __releases(¤t->sighand->siglock)
1785 __acquires(¤t->sighand->siglock)
1787 bool gstop_done = false;
1789 if (arch_ptrace_stop_needed(exit_code, info)) {
1791 * The arch code has something special to do before a
1792 * ptrace stop. This is allowed to block, e.g. for faults
1793 * on user stack pages. We can't keep the siglock while
1794 * calling arch_ptrace_stop, so we must release it now.
1795 * To preserve proper semantics, we must do this before
1796 * any signal bookkeeping like checking group_stop_count.
1797 * Meanwhile, a SIGKILL could come in before we retake the
1798 * siglock. That must prevent us from sleeping in TASK_TRACED.
1799 * So after regaining the lock, we must check for SIGKILL.
1801 spin_unlock_irq(¤t->sighand->siglock);
1802 arch_ptrace_stop(exit_code, info);
1803 spin_lock_irq(¤t->sighand->siglock);
1804 if (sigkill_pending(current))
1809 * We're committing to trapping. TRACED should be visible before
1810 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1811 * Also, transition to TRACED and updates to ->jobctl should be
1812 * atomic with respect to siglock and should be done after the arch
1813 * hook as siglock is released and regrabbed across it.
1815 set_current_state(TASK_TRACED);
1817 current->last_siginfo = info;
1818 current->exit_code = exit_code;
1821 * If @why is CLD_STOPPED, we're trapping to participate in a group
1822 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1823 * across siglock relocks since INTERRUPT was scheduled, PENDING
1824 * could be clear now. We act as if SIGCONT is received after
1825 * TASK_TRACED is entered - ignore it.
1827 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1828 gstop_done = task_participate_group_stop(current);
1830 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1831 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1832 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1833 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1835 /* entering a trap, clear TRAPPING */
1836 task_clear_jobctl_trapping(current);
1838 spin_unlock_irq(¤t->sighand->siglock);
1839 read_lock(&tasklist_lock);
1840 if (may_ptrace_stop()) {
1842 * Notify parents of the stop.
1844 * While ptraced, there are two parents - the ptracer and
1845 * the real_parent of the group_leader. The ptracer should
1846 * know about every stop while the real parent is only
1847 * interested in the completion of group stop. The states
1848 * for the two don't interact with each other. Notify
1849 * separately unless they're gonna be duplicates.
1851 do_notify_parent_cldstop(current, true, why);
1852 if (gstop_done && !real_parent_is_ptracer(current))
1853 do_notify_parent_cldstop(current, false, why);
1856 * Don't want to allow preemption here, because
1857 * sys_ptrace() needs this task to be inactive.
1859 * XXX: implement read_unlock_no_resched().
1862 read_unlock(&tasklist_lock);
1863 preempt_enable_no_resched();
1867 * By the time we got the lock, our tracer went away.
1868 * Don't drop the lock yet, another tracer may come.
1870 * If @gstop_done, the ptracer went away between group stop
1871 * completion and here. During detach, it would have set
1872 * JOBCTL_STOP_PENDING on us and we'll re-enter
1873 * TASK_STOPPED in do_signal_stop() on return, so notifying
1874 * the real parent of the group stop completion is enough.
1877 do_notify_parent_cldstop(current, false, why);
1879 __set_current_state(TASK_RUNNING);
1881 current->exit_code = 0;
1882 read_unlock(&tasklist_lock);
1886 * While in TASK_TRACED, we were considered "frozen enough".
1887 * Now that we woke up, it's crucial if we're supposed to be
1888 * frozen that we freeze now before running anything substantial.
1893 * We are back. Now reacquire the siglock before touching
1894 * last_siginfo, so that we are sure to have synchronized with
1895 * any signal-sending on another CPU that wants to examine it.
1897 spin_lock_irq(¤t->sighand->siglock);
1898 current->last_siginfo = NULL;
1900 /* LISTENING can be set only during STOP traps, clear it */
1901 current->jobctl &= ~JOBCTL_LISTENING;
1904 * Queued signals ignored us while we were stopped for tracing.
1905 * So check for any that we should take before resuming user mode.
1906 * This sets TIF_SIGPENDING, but never clears it.
1908 recalc_sigpending_tsk(current);
1911 static void ptrace_do_notify(int signr, int exit_code, int why)
1915 memset(&info, 0, sizeof info);
1916 info.si_signo = signr;
1917 info.si_code = exit_code;
1918 info.si_pid = task_pid_vnr(current);
1919 info.si_uid = current_uid();
1921 /* Let the debugger run. */
1922 ptrace_stop(exit_code, why, 1, &info);
1925 void ptrace_notify(int exit_code)
1927 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1929 spin_lock_irq(¤t->sighand->siglock);
1930 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1931 spin_unlock_irq(¤t->sighand->siglock);
1935 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1936 * @signr: signr causing group stop if initiating
1938 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1939 * and participate in it. If already set, participate in the existing
1940 * group stop. If participated in a group stop (and thus slept), %true is
1941 * returned with siglock released.
1943 * If ptraced, this function doesn't handle stop itself. Instead,
1944 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1945 * untouched. The caller must ensure that INTERRUPT trap handling takes
1946 * places afterwards.
1949 * Must be called with @current->sighand->siglock held, which is released
1953 * %false if group stop is already cancelled or ptrace trap is scheduled.
1954 * %true if participated in group stop.
1956 static bool do_signal_stop(int signr)
1957 __releases(¤t->sighand->siglock)
1959 struct signal_struct *sig = current->signal;
1961 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1962 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1963 struct task_struct *t;
1965 /* signr will be recorded in task->jobctl for retries */
1966 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1968 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1969 unlikely(signal_group_exit(sig)))
1972 * There is no group stop already in progress. We must
1975 * While ptraced, a task may be resumed while group stop is
1976 * still in effect and then receive a stop signal and
1977 * initiate another group stop. This deviates from the
1978 * usual behavior as two consecutive stop signals can't
1979 * cause two group stops when !ptraced. That is why we
1980 * also check !task_is_stopped(t) below.
1982 * The condition can be distinguished by testing whether
1983 * SIGNAL_STOP_STOPPED is already set. Don't generate
1984 * group_exit_code in such case.
1986 * This is not necessary for SIGNAL_STOP_CONTINUED because
1987 * an intervening stop signal is required to cause two
1988 * continued events regardless of ptrace.
1990 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1991 sig->group_exit_code = signr;
1993 WARN_ON_ONCE(!current->ptrace);
1995 sig->group_stop_count = 0;
1997 if (task_set_jobctl_pending(current, signr | gstop))
1998 sig->group_stop_count++;
2000 for (t = next_thread(current); t != current;
2001 t = next_thread(t)) {
2003 * Setting state to TASK_STOPPED for a group
2004 * stop is always done with the siglock held,
2005 * so this check has no races.
2007 if (!task_is_stopped(t) &&
2008 task_set_jobctl_pending(t, signr | gstop)) {
2009 sig->group_stop_count++;
2010 if (likely(!(t->ptrace & PT_SEIZED)))
2011 signal_wake_up(t, 0);
2013 ptrace_trap_notify(t);
2018 if (likely(!current->ptrace)) {
2022 * If there are no other threads in the group, or if there
2023 * is a group stop in progress and we are the last to stop,
2024 * report to the parent.
2026 if (task_participate_group_stop(current))
2027 notify = CLD_STOPPED;
2029 __set_current_state(TASK_STOPPED);
2030 spin_unlock_irq(¤t->sighand->siglock);
2033 * Notify the parent of the group stop completion. Because
2034 * we're not holding either the siglock or tasklist_lock
2035 * here, ptracer may attach inbetween; however, this is for
2036 * group stop and should always be delivered to the real
2037 * parent of the group leader. The new ptracer will get
2038 * its notification when this task transitions into
2042 read_lock(&tasklist_lock);
2043 do_notify_parent_cldstop(current, false, notify);
2044 read_unlock(&tasklist_lock);
2047 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2052 * While ptraced, group stop is handled by STOP trap.
2053 * Schedule it and let the caller deal with it.
2055 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2061 * do_jobctl_trap - take care of ptrace jobctl traps
2063 * When PT_SEIZED, it's used for both group stop and explicit
2064 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2065 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2066 * the stop signal; otherwise, %SIGTRAP.
2068 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2069 * number as exit_code and no siginfo.
2072 * Must be called with @current->sighand->siglock held, which may be
2073 * released and re-acquired before returning with intervening sleep.
2075 static void do_jobctl_trap(void)
2077 struct signal_struct *signal = current->signal;
2078 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2080 if (current->ptrace & PT_SEIZED) {
2081 if (!signal->group_stop_count &&
2082 !(signal->flags & SIGNAL_STOP_STOPPED))
2084 WARN_ON_ONCE(!signr);
2085 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2088 WARN_ON_ONCE(!signr);
2089 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2090 current->exit_code = 0;
2094 static int ptrace_signal(int signr, siginfo_t *info,
2095 struct pt_regs *regs, void *cookie)
2097 if (!current->ptrace)
2100 ptrace_signal_deliver(regs, cookie);
2102 /* Let the debugger run. */
2103 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2105 /* We're back. Did the debugger cancel the sig? */
2106 signr = current->exit_code;
2110 current->exit_code = 0;
2113 * Update the siginfo structure if the signal has
2114 * changed. If the debugger wanted something
2115 * specific in the siginfo structure then it should
2116 * have updated *info via PTRACE_SETSIGINFO.
2118 if (signr != info->si_signo) {
2119 info->si_signo = signr;
2121 info->si_code = SI_USER;
2122 info->si_pid = task_pid_vnr(current->parent);
2123 info->si_uid = task_uid(current->parent);
2126 /* If the (new) signal is now blocked, requeue it. */
2127 if (sigismember(¤t->blocked, signr)) {
2128 specific_send_sig_info(signr, info, current);
2135 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2136 struct pt_regs *regs, void *cookie)
2138 struct sighand_struct *sighand = current->sighand;
2139 struct signal_struct *signal = current->signal;
2144 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2145 * While in TASK_STOPPED, we were considered "frozen enough".
2146 * Now that we woke up, it's crucial if we're supposed to be
2147 * frozen that we freeze now before running anything substantial.
2151 spin_lock_irq(&sighand->siglock);
2153 * Every stopped thread goes here after wakeup. Check to see if
2154 * we should notify the parent, prepare_signal(SIGCONT) encodes
2155 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2157 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2158 struct task_struct *leader;
2161 if (signal->flags & SIGNAL_CLD_CONTINUED)
2162 why = CLD_CONTINUED;
2166 signal->flags &= ~SIGNAL_CLD_MASK;
2168 spin_unlock_irq(&sighand->siglock);
2171 * Notify the parent that we're continuing. This event is
2172 * always per-process and doesn't make whole lot of sense
2173 * for ptracers, who shouldn't consume the state via
2174 * wait(2) either, but, for backward compatibility, notify
2175 * the ptracer of the group leader too unless it's gonna be
2178 read_lock(&tasklist_lock);
2180 do_notify_parent_cldstop(current, false, why);
2182 leader = current->group_leader;
2183 if (leader->ptrace && !real_parent_is_ptracer(leader))
2184 do_notify_parent_cldstop(leader, true, why);
2186 read_unlock(&tasklist_lock);
2192 struct k_sigaction *ka;
2194 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2198 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2200 spin_unlock_irq(&sighand->siglock);
2204 signr = dequeue_signal(current, ¤t->blocked, info);
2207 break; /* will return 0 */
2209 if (signr != SIGKILL) {
2210 signr = ptrace_signal(signr, info,
2216 ka = &sighand->action[signr-1];
2218 /* Trace actually delivered signals. */
2219 trace_signal_deliver(signr, info, ka);
2221 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2223 if (ka->sa.sa_handler != SIG_DFL) {
2224 /* Run the handler. */
2227 if (ka->sa.sa_flags & SA_ONESHOT)
2228 ka->sa.sa_handler = SIG_DFL;
2230 break; /* will return non-zero "signr" value */
2234 * Now we are doing the default action for this signal.
2236 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2240 * Global init gets no signals it doesn't want.
2241 * Container-init gets no signals it doesn't want from same
2244 * Note that if global/container-init sees a sig_kernel_only()
2245 * signal here, the signal must have been generated internally
2246 * or must have come from an ancestor namespace. In either
2247 * case, the signal cannot be dropped.
2249 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2250 !sig_kernel_only(signr))
2253 if (sig_kernel_stop(signr)) {
2255 * The default action is to stop all threads in
2256 * the thread group. The job control signals
2257 * do nothing in an orphaned pgrp, but SIGSTOP
2258 * always works. Note that siglock needs to be
2259 * dropped during the call to is_orphaned_pgrp()
2260 * because of lock ordering with tasklist_lock.
2261 * This allows an intervening SIGCONT to be posted.
2262 * We need to check for that and bail out if necessary.
2264 if (signr != SIGSTOP) {
2265 spin_unlock_irq(&sighand->siglock);
2267 /* signals can be posted during this window */
2269 if (is_current_pgrp_orphaned())
2272 spin_lock_irq(&sighand->siglock);
2275 if (likely(do_signal_stop(info->si_signo))) {
2276 /* It released the siglock. */
2281 * We didn't actually stop, due to a race
2282 * with SIGCONT or something like that.
2287 spin_unlock_irq(&sighand->siglock);
2290 * Anything else is fatal, maybe with a core dump.
2292 current->flags |= PF_SIGNALED;
2294 if (sig_kernel_coredump(signr)) {
2295 if (print_fatal_signals)
2296 print_fatal_signal(regs, info->si_signo);
2298 * If it was able to dump core, this kills all
2299 * other threads in the group and synchronizes with
2300 * their demise. If we lost the race with another
2301 * thread getting here, it set group_exit_code
2302 * first and our do_group_exit call below will use
2303 * that value and ignore the one we pass it.
2305 do_coredump(info->si_signo, info->si_signo, regs);
2309 * Death signals, no core dump.
2311 do_group_exit(info->si_signo);
2314 spin_unlock_irq(&sighand->siglock);
2319 * It could be that complete_signal() picked us to notify about the
2320 * group-wide signal. Other threads should be notified now to take
2321 * the shared signals in @which since we will not.
2323 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2326 struct task_struct *t;
2328 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2329 if (sigisemptyset(&retarget))
2333 while_each_thread(tsk, t) {
2334 if (t->flags & PF_EXITING)
2337 if (!has_pending_signals(&retarget, &t->blocked))
2339 /* Remove the signals this thread can handle. */
2340 sigandsets(&retarget, &retarget, &t->blocked);
2342 if (!signal_pending(t))
2343 signal_wake_up(t, 0);
2345 if (sigisemptyset(&retarget))
2350 void exit_signals(struct task_struct *tsk)
2355 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2356 tsk->flags |= PF_EXITING;
2360 spin_lock_irq(&tsk->sighand->siglock);
2362 * From now this task is not visible for group-wide signals,
2363 * see wants_signal(), do_signal_stop().
2365 tsk->flags |= PF_EXITING;
2366 if (!signal_pending(tsk))
2369 unblocked = tsk->blocked;
2370 signotset(&unblocked);
2371 retarget_shared_pending(tsk, &unblocked);
2373 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2374 task_participate_group_stop(tsk))
2375 group_stop = CLD_STOPPED;
2377 spin_unlock_irq(&tsk->sighand->siglock);
2380 * If group stop has completed, deliver the notification. This
2381 * should always go to the real parent of the group leader.
2383 if (unlikely(group_stop)) {
2384 read_lock(&tasklist_lock);
2385 do_notify_parent_cldstop(tsk, false, group_stop);
2386 read_unlock(&tasklist_lock);
2390 EXPORT_SYMBOL(recalc_sigpending);
2391 EXPORT_SYMBOL_GPL(dequeue_signal);
2392 EXPORT_SYMBOL(flush_signals);
2393 EXPORT_SYMBOL(force_sig);
2394 EXPORT_SYMBOL(send_sig);
2395 EXPORT_SYMBOL(send_sig_info);
2396 EXPORT_SYMBOL(sigprocmask);
2397 EXPORT_SYMBOL(block_all_signals);
2398 EXPORT_SYMBOL(unblock_all_signals);
2402 * System call entry points.
2406 * sys_restart_syscall - restart a system call
2408 SYSCALL_DEFINE0(restart_syscall)
2410 struct restart_block *restart = ¤t_thread_info()->restart_block;
2411 return restart->fn(restart);
2414 long do_no_restart_syscall(struct restart_block *param)
2419 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2421 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2422 sigset_t newblocked;
2423 /* A set of now blocked but previously unblocked signals. */
2424 sigandnsets(&newblocked, newset, ¤t->blocked);
2425 retarget_shared_pending(tsk, &newblocked);
2427 tsk->blocked = *newset;
2428 recalc_sigpending();
2432 * set_current_blocked - change current->blocked mask
2435 * It is wrong to change ->blocked directly, this helper should be used
2436 * to ensure the process can't miss a shared signal we are going to block.
2438 void set_current_blocked(const sigset_t *newset)
2440 struct task_struct *tsk = current;
2442 spin_lock_irq(&tsk->sighand->siglock);
2443 __set_task_blocked(tsk, newset);
2444 spin_unlock_irq(&tsk->sighand->siglock);
2448 * This is also useful for kernel threads that want to temporarily
2449 * (or permanently) block certain signals.
2451 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2452 * interface happily blocks "unblockable" signals like SIGKILL
2455 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2457 struct task_struct *tsk = current;
2460 /* Lockless, only current can change ->blocked, never from irq */
2462 *oldset = tsk->blocked;
2466 sigorsets(&newset, &tsk->blocked, set);
2469 sigandnsets(&newset, &tsk->blocked, set);
2478 set_current_blocked(&newset);
2483 * sys_rt_sigprocmask - change the list of currently blocked signals
2484 * @how: whether to add, remove, or set signals
2485 * @set: stores pending signals
2486 * @oset: previous value of signal mask if non-null
2487 * @sigsetsize: size of sigset_t type
2489 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2490 sigset_t __user *, oset, size_t, sigsetsize)
2492 sigset_t old_set, new_set;
2495 /* XXX: Don't preclude handling different sized sigset_t's. */
2496 if (sigsetsize != sizeof(sigset_t))
2499 old_set = current->blocked;
2502 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2504 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2506 error = sigprocmask(how, &new_set, NULL);
2512 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2519 long do_sigpending(void __user *set, unsigned long sigsetsize)
2521 long error = -EINVAL;
2524 if (sigsetsize > sizeof(sigset_t))
2527 spin_lock_irq(¤t->sighand->siglock);
2528 sigorsets(&pending, ¤t->pending.signal,
2529 ¤t->signal->shared_pending.signal);
2530 spin_unlock_irq(¤t->sighand->siglock);
2532 /* Outside the lock because only this thread touches it. */
2533 sigandsets(&pending, ¤t->blocked, &pending);
2536 if (!copy_to_user(set, &pending, sigsetsize))
2544 * sys_rt_sigpending - examine a pending signal that has been raised
2546 * @set: stores pending signals
2547 * @sigsetsize: size of sigset_t type or larger
2549 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2551 return do_sigpending(set, sigsetsize);
2554 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2556 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2560 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2562 if (from->si_code < 0)
2563 return __copy_to_user(to, from, sizeof(siginfo_t))
2566 * If you change siginfo_t structure, please be sure
2567 * this code is fixed accordingly.
2568 * Please remember to update the signalfd_copyinfo() function
2569 * inside fs/signalfd.c too, in case siginfo_t changes.
2570 * It should never copy any pad contained in the structure
2571 * to avoid security leaks, but must copy the generic
2572 * 3 ints plus the relevant union member.
2574 err = __put_user(from->si_signo, &to->si_signo);
2575 err |= __put_user(from->si_errno, &to->si_errno);
2576 err |= __put_user((short)from->si_code, &to->si_code);
2577 switch (from->si_code & __SI_MASK) {
2579 err |= __put_user(from->si_pid, &to->si_pid);
2580 err |= __put_user(from->si_uid, &to->si_uid);
2583 err |= __put_user(from->si_tid, &to->si_tid);
2584 err |= __put_user(from->si_overrun, &to->si_overrun);
2585 err |= __put_user(from->si_ptr, &to->si_ptr);
2588 err |= __put_user(from->si_band, &to->si_band);
2589 err |= __put_user(from->si_fd, &to->si_fd);
2592 err |= __put_user(from->si_addr, &to->si_addr);
2593 #ifdef __ARCH_SI_TRAPNO
2594 err |= __put_user(from->si_trapno, &to->si_trapno);
2596 #ifdef BUS_MCEERR_AO
2598 * Other callers might not initialize the si_lsb field,
2599 * so check explicitly for the right codes here.
2601 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2602 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2606 err |= __put_user(from->si_pid, &to->si_pid);
2607 err |= __put_user(from->si_uid, &to->si_uid);
2608 err |= __put_user(from->si_status, &to->si_status);
2609 err |= __put_user(from->si_utime, &to->si_utime);
2610 err |= __put_user(from->si_stime, &to->si_stime);
2612 case __SI_RT: /* This is not generated by the kernel as of now. */
2613 case __SI_MESGQ: /* But this is */
2614 err |= __put_user(from->si_pid, &to->si_pid);
2615 err |= __put_user(from->si_uid, &to->si_uid);
2616 err |= __put_user(from->si_ptr, &to->si_ptr);
2618 default: /* this is just in case for now ... */
2619 err |= __put_user(from->si_pid, &to->si_pid);
2620 err |= __put_user(from->si_uid, &to->si_uid);
2629 * do_sigtimedwait - wait for queued signals specified in @which
2630 * @which: queued signals to wait for
2631 * @info: if non-null, the signal's siginfo is returned here
2632 * @ts: upper bound on process time suspension
2634 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2635 const struct timespec *ts)
2637 struct task_struct *tsk = current;
2638 long timeout = MAX_SCHEDULE_TIMEOUT;
2639 sigset_t mask = *which;
2643 if (!timespec_valid(ts))
2645 timeout = timespec_to_jiffies(ts);
2647 * We can be close to the next tick, add another one
2648 * to ensure we will wait at least the time asked for.
2650 if (ts->tv_sec || ts->tv_nsec)
2655 * Invert the set of allowed signals to get those we want to block.
2657 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2660 spin_lock_irq(&tsk->sighand->siglock);
2661 sig = dequeue_signal(tsk, &mask, info);
2662 if (!sig && timeout) {
2664 * None ready, temporarily unblock those we're interested
2665 * while we are sleeping in so that we'll be awakened when
2666 * they arrive. Unblocking is always fine, we can avoid
2667 * set_current_blocked().
2669 tsk->real_blocked = tsk->blocked;
2670 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2671 recalc_sigpending();
2672 spin_unlock_irq(&tsk->sighand->siglock);
2674 timeout = schedule_timeout_interruptible(timeout);
2676 spin_lock_irq(&tsk->sighand->siglock);
2677 __set_task_blocked(tsk, &tsk->real_blocked);
2678 siginitset(&tsk->real_blocked, 0);
2679 sig = dequeue_signal(tsk, &mask, info);
2681 spin_unlock_irq(&tsk->sighand->siglock);
2685 return timeout ? -EINTR : -EAGAIN;
2689 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2691 * @uthese: queued signals to wait for
2692 * @uinfo: if non-null, the signal's siginfo is returned here
2693 * @uts: upper bound on process time suspension
2694 * @sigsetsize: size of sigset_t type
2696 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2697 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2705 /* XXX: Don't preclude handling different sized sigset_t's. */
2706 if (sigsetsize != sizeof(sigset_t))
2709 if (copy_from_user(&these, uthese, sizeof(these)))
2713 if (copy_from_user(&ts, uts, sizeof(ts)))
2717 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2719 if (ret > 0 && uinfo) {
2720 if (copy_siginfo_to_user(uinfo, &info))
2728 * sys_kill - send a signal to a process
2729 * @pid: the PID of the process
2730 * @sig: signal to be sent
2732 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2734 struct siginfo info;
2736 info.si_signo = sig;
2738 info.si_code = SI_USER;
2739 info.si_pid = task_tgid_vnr(current);
2740 info.si_uid = current_uid();
2742 return kill_something_info(sig, &info, pid);
2746 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2748 struct task_struct *p;
2752 p = find_task_by_vpid(pid);
2753 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2754 error = check_kill_permission(sig, info, p);
2756 * The null signal is a permissions and process existence
2757 * probe. No signal is actually delivered.
2759 if (!error && sig) {
2760 error = do_send_sig_info(sig, info, p, false);
2762 * If lock_task_sighand() failed we pretend the task
2763 * dies after receiving the signal. The window is tiny,
2764 * and the signal is private anyway.
2766 if (unlikely(error == -ESRCH))
2775 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2777 struct siginfo info;
2779 info.si_signo = sig;
2781 info.si_code = SI_TKILL;
2782 info.si_pid = task_tgid_vnr(current);
2783 info.si_uid = current_uid();
2785 return do_send_specific(tgid, pid, sig, &info);
2789 * sys_tgkill - send signal to one specific thread
2790 * @tgid: the thread group ID of the thread
2791 * @pid: the PID of the thread
2792 * @sig: signal to be sent
2794 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2795 * exists but it's not belonging to the target process anymore. This
2796 * method solves the problem of threads exiting and PIDs getting reused.
2798 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2800 /* This is only valid for single tasks */
2801 if (pid <= 0 || tgid <= 0)
2804 return do_tkill(tgid, pid, sig);
2808 * sys_tkill - send signal to one specific task
2809 * @pid: the PID of the task
2810 * @sig: signal to be sent
2812 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2814 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2816 /* This is only valid for single tasks */
2820 return do_tkill(0, pid, sig);
2824 * sys_rt_sigqueueinfo - send signal information to a signal
2825 * @pid: the PID of the thread
2826 * @sig: signal to be sent
2827 * @uinfo: signal info to be sent
2829 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2830 siginfo_t __user *, uinfo)
2834 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2837 /* Not even root can pretend to send signals from the kernel.
2838 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2840 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2841 /* We used to allow any < 0 si_code */
2842 WARN_ON_ONCE(info.si_code < 0);
2845 info.si_signo = sig;
2847 /* POSIX.1b doesn't mention process groups. */
2848 return kill_proc_info(sig, &info, pid);
2851 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2853 /* This is only valid for single tasks */
2854 if (pid <= 0 || tgid <= 0)
2857 /* Not even root can pretend to send signals from the kernel.
2858 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2860 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2861 /* We used to allow any < 0 si_code */
2862 WARN_ON_ONCE(info->si_code < 0);
2865 info->si_signo = sig;
2867 return do_send_specific(tgid, pid, sig, info);
2870 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2871 siginfo_t __user *, uinfo)
2875 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2878 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2881 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2883 struct task_struct *t = current;
2884 struct k_sigaction *k;
2887 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2890 k = &t->sighand->action[sig-1];
2892 spin_lock_irq(¤t->sighand->siglock);
2897 sigdelsetmask(&act->sa.sa_mask,
2898 sigmask(SIGKILL) | sigmask(SIGSTOP));
2902 * "Setting a signal action to SIG_IGN for a signal that is
2903 * pending shall cause the pending signal to be discarded,
2904 * whether or not it is blocked."
2906 * "Setting a signal action to SIG_DFL for a signal that is
2907 * pending and whose default action is to ignore the signal
2908 * (for example, SIGCHLD), shall cause the pending signal to
2909 * be discarded, whether or not it is blocked"
2911 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2913 sigaddset(&mask, sig);
2914 rm_from_queue_full(&mask, &t->signal->shared_pending);
2916 rm_from_queue_full(&mask, &t->pending);
2918 } while (t != current);
2922 spin_unlock_irq(¤t->sighand->siglock);
2927 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2932 oss.ss_sp = (void __user *) current->sas_ss_sp;
2933 oss.ss_size = current->sas_ss_size;
2934 oss.ss_flags = sas_ss_flags(sp);
2942 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
2944 error = __get_user(ss_sp, &uss->ss_sp) |
2945 __get_user(ss_flags, &uss->ss_flags) |
2946 __get_user(ss_size, &uss->ss_size);
2951 if (on_sig_stack(sp))
2956 * Note - this code used to test ss_flags incorrectly:
2957 * old code may have been written using ss_flags==0
2958 * to mean ss_flags==SS_ONSTACK (as this was the only
2959 * way that worked) - this fix preserves that older
2962 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2965 if (ss_flags == SS_DISABLE) {
2970 if (ss_size < MINSIGSTKSZ)
2974 current->sas_ss_sp = (unsigned long) ss_sp;
2975 current->sas_ss_size = ss_size;
2981 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
2983 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
2984 __put_user(oss.ss_size, &uoss->ss_size) |
2985 __put_user(oss.ss_flags, &uoss->ss_flags);
2992 #ifdef __ARCH_WANT_SYS_SIGPENDING
2995 * sys_sigpending - examine pending signals
2996 * @set: where mask of pending signal is returned
2998 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3000 return do_sigpending(set, sizeof(*set));
3005 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3007 * sys_sigprocmask - examine and change blocked signals
3008 * @how: whether to add, remove, or set signals
3009 * @nset: signals to add or remove (if non-null)
3010 * @oset: previous value of signal mask if non-null
3012 * Some platforms have their own version with special arguments;
3013 * others support only sys_rt_sigprocmask.
3016 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3017 old_sigset_t __user *, oset)
3019 old_sigset_t old_set, new_set;
3020 sigset_t new_blocked;
3022 old_set = current->blocked.sig[0];
3025 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3027 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3029 new_blocked = current->blocked;
3033 sigaddsetmask(&new_blocked, new_set);
3036 sigdelsetmask(&new_blocked, new_set);
3039 new_blocked.sig[0] = new_set;
3045 set_current_blocked(&new_blocked);
3049 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3055 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3057 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3059 * sys_rt_sigaction - alter an action taken by a process
3060 * @sig: signal to be sent
3061 * @act: new sigaction
3062 * @oact: used to save the previous sigaction
3063 * @sigsetsize: size of sigset_t type
3065 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3066 const struct sigaction __user *, act,
3067 struct sigaction __user *, oact,
3070 struct k_sigaction new_sa, old_sa;
3073 /* XXX: Don't preclude handling different sized sigset_t's. */
3074 if (sigsetsize != sizeof(sigset_t))
3078 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3082 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3085 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3091 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3093 #ifdef __ARCH_WANT_SYS_SGETMASK
3096 * For backwards compatibility. Functionality superseded by sigprocmask.
3098 SYSCALL_DEFINE0(sgetmask)
3101 return current->blocked.sig[0];
3104 SYSCALL_DEFINE1(ssetmask, int, newmask)
3108 spin_lock_irq(¤t->sighand->siglock);
3109 old = current->blocked.sig[0];
3111 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
3113 recalc_sigpending();
3114 spin_unlock_irq(¤t->sighand->siglock);
3118 #endif /* __ARCH_WANT_SGETMASK */
3120 #ifdef __ARCH_WANT_SYS_SIGNAL
3122 * For backwards compatibility. Functionality superseded by sigaction.
3124 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3126 struct k_sigaction new_sa, old_sa;
3129 new_sa.sa.sa_handler = handler;
3130 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3131 sigemptyset(&new_sa.sa.sa_mask);
3133 ret = do_sigaction(sig, &new_sa, &old_sa);
3135 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3137 #endif /* __ARCH_WANT_SYS_SIGNAL */
3139 #ifdef __ARCH_WANT_SYS_PAUSE
3141 SYSCALL_DEFINE0(pause)
3143 while (!signal_pending(current)) {
3144 current->state = TASK_INTERRUPTIBLE;
3147 return -ERESTARTNOHAND;
3152 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3154 * sys_rt_sigsuspend - replace the signal mask for a value with the
3155 * @unewset value until a signal is received
3156 * @unewset: new signal mask value
3157 * @sigsetsize: size of sigset_t type
3159 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3163 /* XXX: Don't preclude handling different sized sigset_t's. */
3164 if (sigsetsize != sizeof(sigset_t))
3167 if (copy_from_user(&newset, unewset, sizeof(newset)))
3169 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
3171 spin_lock_irq(¤t->sighand->siglock);
3172 current->saved_sigmask = current->blocked;
3173 current->blocked = newset;
3174 recalc_sigpending();
3175 spin_unlock_irq(¤t->sighand->siglock);
3177 current->state = TASK_INTERRUPTIBLE;
3179 set_restore_sigmask();
3180 return -ERESTARTNOHAND;
3182 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3184 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3189 void __init signals_init(void)
3191 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3194 #ifdef CONFIG_KGDB_KDB
3195 #include <linux/kdb.h>
3197 * kdb_send_sig_info - Allows kdb to send signals without exposing
3198 * signal internals. This function checks if the required locks are
3199 * available before calling the main signal code, to avoid kdb
3203 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3205 static struct task_struct *kdb_prev_t;
3207 if (!spin_trylock(&t->sighand->siglock)) {
3208 kdb_printf("Can't do kill command now.\n"
3209 "The sigmask lock is held somewhere else in "
3210 "kernel, try again later\n");
3213 spin_unlock(&t->sighand->siglock);
3214 new_t = kdb_prev_t != t;
3216 if (t->state != TASK_RUNNING && new_t) {
3217 kdb_printf("Process is not RUNNING, sending a signal from "
3218 "kdb risks deadlock\n"
3219 "on the run queue locks. "
3220 "The signal has _not_ been sent.\n"
3221 "Reissue the kill command if you want to risk "
3225 sig = info->si_signo;
3226 if (send_sig_info(sig, info, t))
3227 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3230 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3232 #endif /* CONFIG_KGDB_KDB */