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/export.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/coredump.h>
21 #include <linux/security.h>
22 #include <linux/syscalls.h>
23 #include <linux/ptrace.h>
24 #include <linux/signal.h>
25 #include <linux/signalfd.h>
26 #include <linux/ratelimit.h>
27 #include <linux/tracehook.h>
28 #include <linux/capability.h>
29 #include <linux/freezer.h>
30 #include <linux/pid_namespace.h>
31 #include <linux/nsproxy.h>
32 #include <linux/user_namespace.h>
33 #include <linux/uprobes.h>
34 #define CREATE_TRACE_POINTS
35 #include <trace/events/signal.h>
37 #include <asm/param.h>
38 #include <asm/uaccess.h>
39 #include <asm/unistd.h>
40 #include <asm/siginfo.h>
41 #include <asm/cacheflush.h>
42 #include "audit.h" /* audit_signal_info() */
45 * SLAB caches for signal bits.
48 static struct kmem_cache *sigqueue_cachep;
50 int print_fatal_signals __read_mostly;
52 static void __user *sig_handler(struct task_struct *t, int sig)
54 return t->sighand->action[sig - 1].sa.sa_handler;
57 static int sig_handler_ignored(void __user *handler, int sig)
59 /* Is it explicitly or implicitly ignored? */
60 return handler == SIG_IGN ||
61 (handler == SIG_DFL && sig_kernel_ignore(sig));
64 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
68 handler = sig_handler(t, sig);
70 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
71 handler == SIG_DFL && !force)
74 return sig_handler_ignored(handler, sig);
77 static int sig_ignored(struct task_struct *t, int sig, bool force)
80 * Blocked signals are never ignored, since the
81 * signal handler may change by the time it is
84 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
87 if (!sig_task_ignored(t, sig, force))
91 * Tracers may want to know about even ignored signals.
97 * Re-calculate pending state from the set of locally pending
98 * signals, globally pending signals, and blocked signals.
100 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105 switch (_NSIG_WORDS) {
107 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
108 ready |= signal->sig[i] &~ blocked->sig[i];
111 case 4: ready = signal->sig[3] &~ blocked->sig[3];
112 ready |= signal->sig[2] &~ blocked->sig[2];
113 ready |= signal->sig[1] &~ blocked->sig[1];
114 ready |= signal->sig[0] &~ blocked->sig[0];
117 case 2: ready = signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
121 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
128 static int recalc_sigpending_tsk(struct task_struct *t)
130 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
131 PENDING(&t->pending, &t->blocked) ||
132 PENDING(&t->signal->shared_pending, &t->blocked)) {
133 set_tsk_thread_flag(t, TIF_SIGPENDING);
137 * We must never clear the flag in another thread, or in current
138 * when it's possible the current syscall is returning -ERESTART*.
139 * So we don't clear it here, and only callers who know they should do.
145 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
146 * This is superfluous when called on current, the wakeup is a harmless no-op.
148 void recalc_sigpending_and_wake(struct task_struct *t)
150 if (recalc_sigpending_tsk(t))
151 signal_wake_up(t, 0);
154 void recalc_sigpending(void)
156 if (!recalc_sigpending_tsk(current) && !freezing(current))
157 clear_thread_flag(TIF_SIGPENDING);
161 /* Given the mask, find the first available signal that should be serviced. */
163 #define SYNCHRONOUS_MASK \
164 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
165 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
167 int next_signal(struct sigpending *pending, sigset_t *mask)
169 unsigned long i, *s, *m, x;
172 s = pending->signal.sig;
176 * Handle the first word specially: it contains the
177 * synchronous signals that need to be dequeued first.
181 if (x & SYNCHRONOUS_MASK)
182 x &= SYNCHRONOUS_MASK;
187 switch (_NSIG_WORDS) {
189 for (i = 1; i < _NSIG_WORDS; ++i) {
193 sig = ffz(~x) + i*_NSIG_BPW + 1;
202 sig = ffz(~x) + _NSIG_BPW + 1;
213 static inline void print_dropped_signal(int sig)
215 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
217 if (!print_fatal_signals)
220 if (!__ratelimit(&ratelimit_state))
223 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
224 current->comm, current->pid, sig);
228 * task_set_jobctl_pending - set jobctl pending bits
230 * @mask: pending bits to set
232 * Clear @mask from @task->jobctl. @mask must be subset of
233 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
234 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
235 * cleared. If @task is already being killed or exiting, this function
239 * Must be called with @task->sighand->siglock held.
242 * %true if @mask is set, %false if made noop because @task was dying.
244 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
246 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
247 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
248 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
250 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
253 if (mask & JOBCTL_STOP_SIGMASK)
254 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
256 task->jobctl |= mask;
261 * task_clear_jobctl_trapping - clear jobctl trapping bit
264 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
265 * Clear it and wake up the ptracer. Note that we don't need any further
266 * locking. @task->siglock guarantees that @task->parent points to the
270 * Must be called with @task->sighand->siglock held.
272 void task_clear_jobctl_trapping(struct task_struct *task)
274 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
275 task->jobctl &= ~JOBCTL_TRAPPING;
276 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
281 * task_clear_jobctl_pending - clear jobctl pending bits
283 * @mask: pending bits to clear
285 * Clear @mask from @task->jobctl. @mask must be subset of
286 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
287 * STOP bits are cleared together.
289 * If clearing of @mask leaves no stop or trap pending, this function calls
290 * task_clear_jobctl_trapping().
293 * Must be called with @task->sighand->siglock held.
295 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
297 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
299 if (mask & JOBCTL_STOP_PENDING)
300 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
302 task->jobctl &= ~mask;
304 if (!(task->jobctl & JOBCTL_PENDING_MASK))
305 task_clear_jobctl_trapping(task);
309 * task_participate_group_stop - participate in a group stop
310 * @task: task participating in a group stop
312 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
313 * Group stop states are cleared and the group stop count is consumed if
314 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
315 * stop, the appropriate %SIGNAL_* flags are set.
318 * Must be called with @task->sighand->siglock held.
321 * %true if group stop completion should be notified to the parent, %false
324 static bool task_participate_group_stop(struct task_struct *task)
326 struct signal_struct *sig = task->signal;
327 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
329 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
331 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
336 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
337 sig->group_stop_count--;
340 * Tell the caller to notify completion iff we are entering into a
341 * fresh group stop. Read comment in do_signal_stop() for details.
343 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
344 sig->flags = SIGNAL_STOP_STOPPED;
351 * allocate a new signal queue record
352 * - this may be called without locks if and only if t == current, otherwise an
353 * appropriate lock must be held to stop the target task from exiting
355 static struct sigqueue *
356 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
358 struct sigqueue *q = NULL;
359 struct user_struct *user;
362 * Protect access to @t credentials. This can go away when all
363 * callers hold rcu read lock.
366 user = get_uid(__task_cred(t)->user);
367 atomic_inc(&user->sigpending);
370 if (override_rlimit ||
371 atomic_read(&user->sigpending) <=
372 task_rlimit(t, RLIMIT_SIGPENDING)) {
373 q = kmem_cache_alloc(sigqueue_cachep, flags);
375 print_dropped_signal(sig);
378 if (unlikely(q == NULL)) {
379 atomic_dec(&user->sigpending);
382 INIT_LIST_HEAD(&q->list);
390 static void __sigqueue_free(struct sigqueue *q)
392 if (q->flags & SIGQUEUE_PREALLOC)
394 atomic_dec(&q->user->sigpending);
396 kmem_cache_free(sigqueue_cachep, q);
399 void flush_sigqueue(struct sigpending *queue)
403 sigemptyset(&queue->signal);
404 while (!list_empty(&queue->list)) {
405 q = list_entry(queue->list.next, struct sigqueue , list);
406 list_del_init(&q->list);
412 * Flush all pending signals for a task.
414 void __flush_signals(struct task_struct *t)
416 clear_tsk_thread_flag(t, TIF_SIGPENDING);
417 flush_sigqueue(&t->pending);
418 flush_sigqueue(&t->signal->shared_pending);
421 void flush_signals(struct task_struct *t)
425 spin_lock_irqsave(&t->sighand->siglock, flags);
427 spin_unlock_irqrestore(&t->sighand->siglock, flags);
430 static void __flush_itimer_signals(struct sigpending *pending)
432 sigset_t signal, retain;
433 struct sigqueue *q, *n;
435 signal = pending->signal;
436 sigemptyset(&retain);
438 list_for_each_entry_safe(q, n, &pending->list, list) {
439 int sig = q->info.si_signo;
441 if (likely(q->info.si_code != SI_TIMER)) {
442 sigaddset(&retain, sig);
444 sigdelset(&signal, sig);
445 list_del_init(&q->list);
450 sigorsets(&pending->signal, &signal, &retain);
453 void flush_itimer_signals(void)
455 struct task_struct *tsk = current;
458 spin_lock_irqsave(&tsk->sighand->siglock, flags);
459 __flush_itimer_signals(&tsk->pending);
460 __flush_itimer_signals(&tsk->signal->shared_pending);
461 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
464 void ignore_signals(struct task_struct *t)
468 for (i = 0; i < _NSIG; ++i)
469 t->sighand->action[i].sa.sa_handler = SIG_IGN;
475 * Flush all handlers for a task.
479 flush_signal_handlers(struct task_struct *t, int force_default)
482 struct k_sigaction *ka = &t->sighand->action[0];
483 for (i = _NSIG ; i != 0 ; i--) {
484 if (force_default || ka->sa.sa_handler != SIG_IGN)
485 ka->sa.sa_handler = SIG_DFL;
487 sigemptyset(&ka->sa.sa_mask);
492 int unhandled_signal(struct task_struct *tsk, int sig)
494 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
495 if (is_global_init(tsk))
497 if (handler != SIG_IGN && handler != SIG_DFL)
499 /* if ptraced, let the tracer determine */
504 * Notify the system that a driver wants to block all signals for this
505 * process, and wants to be notified if any signals at all were to be
506 * sent/acted upon. If the notifier routine returns non-zero, then the
507 * signal will be acted upon after all. If the notifier routine returns 0,
508 * then then signal will be blocked. Only one block per process is
509 * allowed. priv is a pointer to private data that the notifier routine
510 * can use to determine if the signal should be blocked or not.
513 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
517 spin_lock_irqsave(¤t->sighand->siglock, flags);
518 current->notifier_mask = mask;
519 current->notifier_data = priv;
520 current->notifier = notifier;
521 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
524 /* Notify the system that blocking has ended. */
527 unblock_all_signals(void)
531 spin_lock_irqsave(¤t->sighand->siglock, flags);
532 current->notifier = NULL;
533 current->notifier_data = NULL;
535 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
538 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
540 struct sigqueue *q, *first = NULL;
543 * Collect the siginfo appropriate to this signal. Check if
544 * there is another siginfo for the same signal.
546 list_for_each_entry(q, &list->list, list) {
547 if (q->info.si_signo == sig) {
554 sigdelset(&list->signal, sig);
558 list_del_init(&first->list);
559 copy_siginfo(info, &first->info);
560 __sigqueue_free(first);
563 * Ok, it wasn't in the queue. This must be
564 * a fast-pathed signal or we must have been
565 * out of queue space. So zero out the info.
567 info->si_signo = sig;
569 info->si_code = SI_USER;
575 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
578 int sig = next_signal(pending, mask);
581 if (current->notifier) {
582 if (sigismember(current->notifier_mask, sig)) {
583 if (!(current->notifier)(current->notifier_data)) {
584 clear_thread_flag(TIF_SIGPENDING);
590 collect_signal(sig, pending, info);
597 * Dequeue a signal and return the element to the caller, which is
598 * expected to free it.
600 * All callers have to hold the siglock.
602 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
606 /* We only dequeue private signals from ourselves, we don't let
607 * signalfd steal them
609 signr = __dequeue_signal(&tsk->pending, mask, info);
611 signr = __dequeue_signal(&tsk->signal->shared_pending,
616 * itimers are process shared and we restart periodic
617 * itimers in the signal delivery path to prevent DoS
618 * attacks in the high resolution timer case. This is
619 * compliant with the old way of self-restarting
620 * itimers, as the SIGALRM is a legacy signal and only
621 * queued once. Changing the restart behaviour to
622 * restart the timer in the signal dequeue path is
623 * reducing the timer noise on heavy loaded !highres
626 if (unlikely(signr == SIGALRM)) {
627 struct hrtimer *tmr = &tsk->signal->real_timer;
629 if (!hrtimer_is_queued(tmr) &&
630 tsk->signal->it_real_incr.tv64 != 0) {
631 hrtimer_forward(tmr, tmr->base->get_time(),
632 tsk->signal->it_real_incr);
633 hrtimer_restart(tmr);
642 if (unlikely(sig_kernel_stop(signr))) {
644 * Set a marker that we have dequeued a stop signal. Our
645 * caller might release the siglock and then the pending
646 * stop signal it is about to process is no longer in the
647 * pending bitmasks, but must still be cleared by a SIGCONT
648 * (and overruled by a SIGKILL). So those cases clear this
649 * shared flag after we've set it. Note that this flag may
650 * remain set after the signal we return is ignored or
651 * handled. That doesn't matter because its only purpose
652 * is to alert stop-signal processing code when another
653 * processor has come along and cleared the flag.
655 current->jobctl |= JOBCTL_STOP_DEQUEUED;
657 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
659 * Release the siglock to ensure proper locking order
660 * of timer locks outside of siglocks. Note, we leave
661 * irqs disabled here, since the posix-timers code is
662 * about to disable them again anyway.
664 spin_unlock(&tsk->sighand->siglock);
665 do_schedule_next_timer(info);
666 spin_lock(&tsk->sighand->siglock);
672 * Tell a process that it has a new active signal..
674 * NOTE! we rely on the previous spin_lock to
675 * lock interrupts for us! We can only be called with
676 * "siglock" held, and the local interrupt must
677 * have been disabled when that got acquired!
679 * No need to set need_resched since signal event passing
680 * goes through ->blocked
682 void signal_wake_up(struct task_struct *t, int resume)
686 set_tsk_thread_flag(t, TIF_SIGPENDING);
689 * For SIGKILL, we want to wake it up in the stopped/traced/killable
690 * case. We don't check t->state here because there is a race with it
691 * executing another processor and just now entering stopped state.
692 * By using wake_up_state, we ensure the process will wake up and
693 * handle its death signal.
695 mask = TASK_INTERRUPTIBLE;
697 mask |= TASK_WAKEKILL;
698 if (!wake_up_state(t, mask))
703 * Remove signals in mask from the pending set and queue.
704 * Returns 1 if any signals were found.
706 * All callers must be holding the siglock.
708 * This version takes a sigset mask and looks at all signals,
709 * not just those in the first mask word.
711 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
713 struct sigqueue *q, *n;
716 sigandsets(&m, mask, &s->signal);
717 if (sigisemptyset(&m))
720 sigandnsets(&s->signal, &s->signal, mask);
721 list_for_each_entry_safe(q, n, &s->list, list) {
722 if (sigismember(mask, q->info.si_signo)) {
723 list_del_init(&q->list);
730 * Remove signals in mask from the pending set and queue.
731 * Returns 1 if any signals were found.
733 * All callers must be holding the siglock.
735 static int rm_from_queue(unsigned long mask, struct sigpending *s)
737 struct sigqueue *q, *n;
739 if (!sigtestsetmask(&s->signal, mask))
742 sigdelsetmask(&s->signal, mask);
743 list_for_each_entry_safe(q, n, &s->list, list) {
744 if (q->info.si_signo < SIGRTMIN &&
745 (mask & sigmask(q->info.si_signo))) {
746 list_del_init(&q->list);
753 static inline int is_si_special(const struct siginfo *info)
755 return info <= SEND_SIG_FORCED;
758 static inline bool si_fromuser(const struct siginfo *info)
760 return info == SEND_SIG_NOINFO ||
761 (!is_si_special(info) && SI_FROMUSER(info));
765 * called with RCU read lock from check_kill_permission()
767 static int kill_ok_by_cred(struct task_struct *t)
769 const struct cred *cred = current_cred();
770 const struct cred *tcred = __task_cred(t);
772 if (uid_eq(cred->euid, tcred->suid) ||
773 uid_eq(cred->euid, tcred->uid) ||
774 uid_eq(cred->uid, tcred->suid) ||
775 uid_eq(cred->uid, tcred->uid))
778 if (ns_capable(tcred->user_ns, CAP_KILL))
785 * Bad permissions for sending the signal
786 * - the caller must hold the RCU read lock
788 static int check_kill_permission(int sig, struct siginfo *info,
789 struct task_struct *t)
794 if (!valid_signal(sig))
797 if (!si_fromuser(info))
800 error = audit_signal_info(sig, t); /* Let audit system see the signal */
804 if (!same_thread_group(current, t) &&
805 !kill_ok_by_cred(t)) {
808 sid = task_session(t);
810 * We don't return the error if sid == NULL. The
811 * task was unhashed, the caller must notice this.
813 if (!sid || sid == task_session(current))
820 return security_task_kill(t, info, sig, 0);
824 * ptrace_trap_notify - schedule trap to notify ptracer
825 * @t: tracee wanting to notify tracer
827 * This function schedules sticky ptrace trap which is cleared on the next
828 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
831 * If @t is running, STOP trap will be taken. If trapped for STOP and
832 * ptracer is listening for events, tracee is woken up so that it can
833 * re-trap for the new event. If trapped otherwise, STOP trap will be
834 * eventually taken without returning to userland after the existing traps
835 * are finished by PTRACE_CONT.
838 * Must be called with @task->sighand->siglock held.
840 static void ptrace_trap_notify(struct task_struct *t)
842 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
843 assert_spin_locked(&t->sighand->siglock);
845 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
846 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
850 * Handle magic process-wide effects of stop/continue signals. Unlike
851 * the signal actions, these happen immediately at signal-generation
852 * time regardless of blocking, ignoring, or handling. This does the
853 * actual continuing for SIGCONT, but not the actual stopping for stop
854 * signals. The process stop is done as a signal action for SIG_DFL.
856 * Returns true if the signal should be actually delivered, otherwise
857 * it should be dropped.
859 static int prepare_signal(int sig, struct task_struct *p, bool force)
861 struct signal_struct *signal = p->signal;
862 struct task_struct *t;
864 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
866 * The process is in the middle of dying, nothing to do.
868 } else if (sig_kernel_stop(sig)) {
870 * This is a stop signal. Remove SIGCONT from all queues.
872 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
875 rm_from_queue(sigmask(SIGCONT), &t->pending);
876 } while_each_thread(p, t);
877 } else if (sig == SIGCONT) {
880 * Remove all stop signals from all queues, wake all threads.
882 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
885 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
886 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
887 if (likely(!(t->ptrace & PT_SEIZED)))
888 wake_up_state(t, __TASK_STOPPED);
890 ptrace_trap_notify(t);
891 } while_each_thread(p, t);
894 * Notify the parent with CLD_CONTINUED if we were stopped.
896 * If we were in the middle of a group stop, we pretend it
897 * was already finished, and then continued. Since SIGCHLD
898 * doesn't queue we report only CLD_STOPPED, as if the next
899 * CLD_CONTINUED was dropped.
902 if (signal->flags & SIGNAL_STOP_STOPPED)
903 why |= SIGNAL_CLD_CONTINUED;
904 else if (signal->group_stop_count)
905 why |= SIGNAL_CLD_STOPPED;
909 * The first thread which returns from do_signal_stop()
910 * will take ->siglock, notice SIGNAL_CLD_MASK, and
911 * notify its parent. See get_signal_to_deliver().
913 signal->flags = why | SIGNAL_STOP_CONTINUED;
914 signal->group_stop_count = 0;
915 signal->group_exit_code = 0;
919 return !sig_ignored(p, sig, force);
923 * Test if P wants to take SIG. After we've checked all threads with this,
924 * it's equivalent to finding no threads not blocking SIG. Any threads not
925 * blocking SIG were ruled out because they are not running and already
926 * have pending signals. Such threads will dequeue from the shared queue
927 * as soon as they're available, so putting the signal on the shared queue
928 * will be equivalent to sending it to one such thread.
930 static inline int wants_signal(int sig, struct task_struct *p)
932 if (sigismember(&p->blocked, sig))
934 if (p->flags & PF_EXITING)
938 if (task_is_stopped_or_traced(p))
940 return task_curr(p) || !signal_pending(p);
943 static void complete_signal(int sig, struct task_struct *p, int group)
945 struct signal_struct *signal = p->signal;
946 struct task_struct *t;
949 * Now find a thread we can wake up to take the signal off the queue.
951 * If the main thread wants the signal, it gets first crack.
952 * Probably the least surprising to the average bear.
954 if (wants_signal(sig, p))
956 else if (!group || thread_group_empty(p))
958 * There is just one thread and it does not need to be woken.
959 * It will dequeue unblocked signals before it runs again.
964 * Otherwise try to find a suitable thread.
966 t = signal->curr_target;
967 while (!wants_signal(sig, t)) {
969 if (t == signal->curr_target)
971 * No thread needs to be woken.
972 * Any eligible threads will see
973 * the signal in the queue soon.
977 signal->curr_target = t;
981 * Found a killable thread. If the signal will be fatal,
982 * then start taking the whole group down immediately.
984 if (sig_fatal(p, sig) &&
985 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
986 !sigismember(&t->real_blocked, sig) &&
987 (sig == SIGKILL || !t->ptrace)) {
989 * This signal will be fatal to the whole group.
991 if (!sig_kernel_coredump(sig)) {
993 * Start a group exit and wake everybody up.
994 * This way we don't have other threads
995 * running and doing things after a slower
996 * thread has the fatal signal pending.
998 signal->flags = SIGNAL_GROUP_EXIT;
999 signal->group_exit_code = sig;
1000 signal->group_stop_count = 0;
1003 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1004 sigaddset(&t->pending.signal, SIGKILL);
1005 signal_wake_up(t, 1);
1006 } while_each_thread(p, t);
1012 * The signal is already in the shared-pending queue.
1013 * Tell the chosen thread to wake up and dequeue it.
1015 signal_wake_up(t, sig == SIGKILL);
1019 static inline int legacy_queue(struct sigpending *signals, int sig)
1021 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1024 #ifdef CONFIG_USER_NS
1025 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1027 if (current_user_ns() == task_cred_xxx(t, user_ns))
1030 if (SI_FROMKERNEL(info))
1034 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1035 make_kuid(current_user_ns(), info->si_uid));
1039 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1045 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1046 int group, int from_ancestor_ns)
1048 struct sigpending *pending;
1050 int override_rlimit;
1051 int ret = 0, result;
1053 assert_spin_locked(&t->sighand->siglock);
1055 result = TRACE_SIGNAL_IGNORED;
1056 if (!prepare_signal(sig, t,
1057 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1060 pending = group ? &t->signal->shared_pending : &t->pending;
1062 * Short-circuit ignored signals and support queuing
1063 * exactly one non-rt signal, so that we can get more
1064 * detailed information about the cause of the signal.
1066 result = TRACE_SIGNAL_ALREADY_PENDING;
1067 if (legacy_queue(pending, sig))
1070 result = TRACE_SIGNAL_DELIVERED;
1072 * fast-pathed signals for kernel-internal things like SIGSTOP
1075 if (info == SEND_SIG_FORCED)
1079 * Real-time signals must be queued if sent by sigqueue, or
1080 * some other real-time mechanism. It is implementation
1081 * defined whether kill() does so. We attempt to do so, on
1082 * the principle of least surprise, but since kill is not
1083 * allowed to fail with EAGAIN when low on memory we just
1084 * make sure at least one signal gets delivered and don't
1085 * pass on the info struct.
1088 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1090 override_rlimit = 0;
1092 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1095 list_add_tail(&q->list, &pending->list);
1096 switch ((unsigned long) info) {
1097 case (unsigned long) SEND_SIG_NOINFO:
1098 q->info.si_signo = sig;
1099 q->info.si_errno = 0;
1100 q->info.si_code = SI_USER;
1101 q->info.si_pid = task_tgid_nr_ns(current,
1102 task_active_pid_ns(t));
1103 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1105 case (unsigned long) SEND_SIG_PRIV:
1106 q->info.si_signo = sig;
1107 q->info.si_errno = 0;
1108 q->info.si_code = SI_KERNEL;
1113 copy_siginfo(&q->info, info);
1114 if (from_ancestor_ns)
1119 userns_fixup_signal_uid(&q->info, t);
1121 } else if (!is_si_special(info)) {
1122 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1124 * Queue overflow, abort. We may abort if the
1125 * signal was rt and sent by user using something
1126 * other than kill().
1128 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1133 * This is a silent loss of information. We still
1134 * send the signal, but the *info bits are lost.
1136 result = TRACE_SIGNAL_LOSE_INFO;
1141 signalfd_notify(t, sig);
1142 sigaddset(&pending->signal, sig);
1143 complete_signal(sig, t, group);
1145 trace_signal_generate(sig, info, t, group, result);
1149 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1152 int from_ancestor_ns = 0;
1154 #ifdef CONFIG_PID_NS
1155 from_ancestor_ns = si_fromuser(info) &&
1156 !task_pid_nr_ns(current, task_active_pid_ns(t));
1159 return __send_signal(sig, info, t, group, from_ancestor_ns);
1162 static void print_fatal_signal(struct pt_regs *regs, int signr)
1164 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1165 current->comm, task_pid_nr(current), signr);
1167 #if defined(__i386__) && !defined(__arch_um__)
1168 printk("code at %08lx: ", regs->ip);
1171 for (i = 0; i < 16; i++) {
1174 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1176 printk("%02x ", insn);
1186 static int __init setup_print_fatal_signals(char *str)
1188 get_option (&str, &print_fatal_signals);
1193 __setup("print-fatal-signals=", setup_print_fatal_signals);
1196 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1198 return send_signal(sig, info, p, 1);
1202 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1204 return send_signal(sig, info, t, 0);
1207 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1210 unsigned long flags;
1213 if (lock_task_sighand(p, &flags)) {
1214 ret = send_signal(sig, info, p, group);
1215 unlock_task_sighand(p, &flags);
1222 * Force a signal that the process can't ignore: if necessary
1223 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1225 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1226 * since we do not want to have a signal handler that was blocked
1227 * be invoked when user space had explicitly blocked it.
1229 * We don't want to have recursive SIGSEGV's etc, for example,
1230 * that is why we also clear SIGNAL_UNKILLABLE.
1233 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1235 unsigned long int flags;
1236 int ret, blocked, ignored;
1237 struct k_sigaction *action;
1239 spin_lock_irqsave(&t->sighand->siglock, flags);
1240 action = &t->sighand->action[sig-1];
1241 ignored = action->sa.sa_handler == SIG_IGN;
1242 blocked = sigismember(&t->blocked, sig);
1243 if (blocked || ignored) {
1244 action->sa.sa_handler = SIG_DFL;
1246 sigdelset(&t->blocked, sig);
1247 recalc_sigpending_and_wake(t);
1250 if (action->sa.sa_handler == SIG_DFL)
1251 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1252 ret = specific_send_sig_info(sig, info, t);
1253 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1259 * Nuke all other threads in the group.
1261 int zap_other_threads(struct task_struct *p)
1263 struct task_struct *t = p;
1266 p->signal->group_stop_count = 0;
1268 while_each_thread(p, t) {
1269 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1272 /* Don't bother with already dead threads */
1275 sigaddset(&t->pending.signal, SIGKILL);
1276 signal_wake_up(t, 1);
1282 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1283 unsigned long *flags)
1285 struct sighand_struct *sighand;
1288 local_irq_save(*flags);
1290 sighand = rcu_dereference(tsk->sighand);
1291 if (unlikely(sighand == NULL)) {
1293 local_irq_restore(*flags);
1297 spin_lock(&sighand->siglock);
1298 if (likely(sighand == tsk->sighand)) {
1302 spin_unlock(&sighand->siglock);
1304 local_irq_restore(*flags);
1311 * send signal info to all the members of a group
1313 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1318 ret = check_kill_permission(sig, info, p);
1322 ret = do_send_sig_info(sig, info, p, true);
1328 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1329 * control characters do (^C, ^Z etc)
1330 * - the caller must hold at least a readlock on tasklist_lock
1332 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1334 struct task_struct *p = NULL;
1335 int retval, success;
1339 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1340 int err = group_send_sig_info(sig, info, p);
1343 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1344 return success ? 0 : retval;
1347 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1350 struct task_struct *p;
1354 p = pid_task(pid, PIDTYPE_PID);
1356 error = group_send_sig_info(sig, info, p);
1357 if (unlikely(error == -ESRCH))
1359 * The task was unhashed in between, try again.
1360 * If it is dead, pid_task() will return NULL,
1361 * if we race with de_thread() it will find the
1371 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1375 error = kill_pid_info(sig, info, find_vpid(pid));
1380 static int kill_as_cred_perm(const struct cred *cred,
1381 struct task_struct *target)
1383 const struct cred *pcred = __task_cred(target);
1384 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1385 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1390 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1391 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1392 const struct cred *cred, u32 secid)
1395 struct task_struct *p;
1396 unsigned long flags;
1398 if (!valid_signal(sig))
1402 p = pid_task(pid, PIDTYPE_PID);
1407 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1411 ret = security_task_kill(p, info, sig, secid);
1416 if (lock_task_sighand(p, &flags)) {
1417 ret = __send_signal(sig, info, p, 1, 0);
1418 unlock_task_sighand(p, &flags);
1426 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1429 * kill_something_info() interprets pid in interesting ways just like kill(2).
1431 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1432 * is probably wrong. Should make it like BSD or SYSV.
1435 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1441 ret = kill_pid_info(sig, info, find_vpid(pid));
1446 read_lock(&tasklist_lock);
1448 ret = __kill_pgrp_info(sig, info,
1449 pid ? find_vpid(-pid) : task_pgrp(current));
1451 int retval = 0, count = 0;
1452 struct task_struct * p;
1454 for_each_process(p) {
1455 if (task_pid_vnr(p) > 1 &&
1456 !same_thread_group(p, current)) {
1457 int err = group_send_sig_info(sig, info, p);
1463 ret = count ? retval : -ESRCH;
1465 read_unlock(&tasklist_lock);
1471 * These are for backward compatibility with the rest of the kernel source.
1474 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1477 * Make sure legacy kernel users don't send in bad values
1478 * (normal paths check this in check_kill_permission).
1480 if (!valid_signal(sig))
1483 return do_send_sig_info(sig, info, p, false);
1486 #define __si_special(priv) \
1487 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1490 send_sig(int sig, struct task_struct *p, int priv)
1492 return send_sig_info(sig, __si_special(priv), p);
1496 force_sig(int sig, struct task_struct *p)
1498 force_sig_info(sig, SEND_SIG_PRIV, p);
1502 * When things go south during signal handling, we
1503 * will force a SIGSEGV. And if the signal that caused
1504 * the problem was already a SIGSEGV, we'll want to
1505 * make sure we don't even try to deliver the signal..
1508 force_sigsegv(int sig, struct task_struct *p)
1510 if (sig == SIGSEGV) {
1511 unsigned long flags;
1512 spin_lock_irqsave(&p->sighand->siglock, flags);
1513 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1514 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1516 force_sig(SIGSEGV, p);
1520 int kill_pgrp(struct pid *pid, int sig, int priv)
1524 read_lock(&tasklist_lock);
1525 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1526 read_unlock(&tasklist_lock);
1530 EXPORT_SYMBOL(kill_pgrp);
1532 int kill_pid(struct pid *pid, int sig, int priv)
1534 return kill_pid_info(sig, __si_special(priv), pid);
1536 EXPORT_SYMBOL(kill_pid);
1539 * These functions support sending signals using preallocated sigqueue
1540 * structures. This is needed "because realtime applications cannot
1541 * afford to lose notifications of asynchronous events, like timer
1542 * expirations or I/O completions". In the case of POSIX Timers
1543 * we allocate the sigqueue structure from the timer_create. If this
1544 * allocation fails we are able to report the failure to the application
1545 * with an EAGAIN error.
1547 struct sigqueue *sigqueue_alloc(void)
1549 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1552 q->flags |= SIGQUEUE_PREALLOC;
1557 void sigqueue_free(struct sigqueue *q)
1559 unsigned long flags;
1560 spinlock_t *lock = ¤t->sighand->siglock;
1562 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1564 * We must hold ->siglock while testing q->list
1565 * to serialize with collect_signal() or with
1566 * __exit_signal()->flush_sigqueue().
1568 spin_lock_irqsave(lock, flags);
1569 q->flags &= ~SIGQUEUE_PREALLOC;
1571 * If it is queued it will be freed when dequeued,
1572 * like the "regular" sigqueue.
1574 if (!list_empty(&q->list))
1576 spin_unlock_irqrestore(lock, flags);
1582 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1584 int sig = q->info.si_signo;
1585 struct sigpending *pending;
1586 unsigned long flags;
1589 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1592 if (!likely(lock_task_sighand(t, &flags)))
1595 ret = 1; /* the signal is ignored */
1596 result = TRACE_SIGNAL_IGNORED;
1597 if (!prepare_signal(sig, t, false))
1601 if (unlikely(!list_empty(&q->list))) {
1603 * If an SI_TIMER entry is already queue just increment
1604 * the overrun count.
1606 BUG_ON(q->info.si_code != SI_TIMER);
1607 q->info.si_overrun++;
1608 result = TRACE_SIGNAL_ALREADY_PENDING;
1611 q->info.si_overrun = 0;
1613 signalfd_notify(t, sig);
1614 pending = group ? &t->signal->shared_pending : &t->pending;
1615 list_add_tail(&q->list, &pending->list);
1616 sigaddset(&pending->signal, sig);
1617 complete_signal(sig, t, group);
1618 result = TRACE_SIGNAL_DELIVERED;
1620 trace_signal_generate(sig, &q->info, t, group, result);
1621 unlock_task_sighand(t, &flags);
1627 * Let a parent know about the death of a child.
1628 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1630 * Returns true if our parent ignored us and so we've switched to
1633 bool do_notify_parent(struct task_struct *tsk, int sig)
1635 struct siginfo info;
1636 unsigned long flags;
1637 struct sighand_struct *psig;
1638 bool autoreap = false;
1642 /* do_notify_parent_cldstop should have been called instead. */
1643 BUG_ON(task_is_stopped_or_traced(tsk));
1645 BUG_ON(!tsk->ptrace &&
1646 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1648 if (sig != SIGCHLD) {
1650 * This is only possible if parent == real_parent.
1651 * Check if it has changed security domain.
1653 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1657 info.si_signo = sig;
1660 * We are under tasklist_lock here so our parent is tied to
1661 * us and cannot change.
1663 * task_active_pid_ns will always return the same pid namespace
1664 * until a task passes through release_task.
1666 * write_lock() currently calls preempt_disable() which is the
1667 * same as rcu_read_lock(), but according to Oleg, this is not
1668 * correct to rely on this
1671 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1672 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1676 info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
1677 info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
1679 info.si_status = tsk->exit_code & 0x7f;
1680 if (tsk->exit_code & 0x80)
1681 info.si_code = CLD_DUMPED;
1682 else if (tsk->exit_code & 0x7f)
1683 info.si_code = CLD_KILLED;
1685 info.si_code = CLD_EXITED;
1686 info.si_status = tsk->exit_code >> 8;
1689 psig = tsk->parent->sighand;
1690 spin_lock_irqsave(&psig->siglock, flags);
1691 if (!tsk->ptrace && sig == SIGCHLD &&
1692 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1693 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1695 * We are exiting and our parent doesn't care. POSIX.1
1696 * defines special semantics for setting SIGCHLD to SIG_IGN
1697 * or setting the SA_NOCLDWAIT flag: we should be reaped
1698 * automatically and not left for our parent's wait4 call.
1699 * Rather than having the parent do it as a magic kind of
1700 * signal handler, we just set this to tell do_exit that we
1701 * can be cleaned up without becoming a zombie. Note that
1702 * we still call __wake_up_parent in this case, because a
1703 * blocked sys_wait4 might now return -ECHILD.
1705 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1706 * is implementation-defined: we do (if you don't want
1707 * it, just use SIG_IGN instead).
1710 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1713 if (valid_signal(sig) && sig)
1714 __group_send_sig_info(sig, &info, tsk->parent);
1715 __wake_up_parent(tsk, tsk->parent);
1716 spin_unlock_irqrestore(&psig->siglock, flags);
1722 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1723 * @tsk: task reporting the state change
1724 * @for_ptracer: the notification is for ptracer
1725 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1727 * Notify @tsk's parent that the stopped/continued state has changed. If
1728 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1729 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1732 * Must be called with tasklist_lock at least read locked.
1734 static void do_notify_parent_cldstop(struct task_struct *tsk,
1735 bool for_ptracer, int why)
1737 struct siginfo info;
1738 unsigned long flags;
1739 struct task_struct *parent;
1740 struct sighand_struct *sighand;
1743 parent = tsk->parent;
1745 tsk = tsk->group_leader;
1746 parent = tsk->real_parent;
1749 info.si_signo = SIGCHLD;
1752 * see comment in do_notify_parent() about the following 4 lines
1755 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1756 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1759 info.si_utime = cputime_to_clock_t(tsk->utime);
1760 info.si_stime = cputime_to_clock_t(tsk->stime);
1765 info.si_status = SIGCONT;
1768 info.si_status = tsk->signal->group_exit_code & 0x7f;
1771 info.si_status = tsk->exit_code & 0x7f;
1777 sighand = parent->sighand;
1778 spin_lock_irqsave(&sighand->siglock, flags);
1779 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1780 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1781 __group_send_sig_info(SIGCHLD, &info, parent);
1783 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1785 __wake_up_parent(tsk, parent);
1786 spin_unlock_irqrestore(&sighand->siglock, flags);
1789 static inline int may_ptrace_stop(void)
1791 if (!likely(current->ptrace))
1794 * Are we in the middle of do_coredump?
1795 * If so and our tracer is also part of the coredump stopping
1796 * is a deadlock situation, and pointless because our tracer
1797 * is dead so don't allow us to stop.
1798 * If SIGKILL was already sent before the caller unlocked
1799 * ->siglock we must see ->core_state != NULL. Otherwise it
1800 * is safe to enter schedule().
1802 if (unlikely(current->mm->core_state) &&
1803 unlikely(current->mm == current->parent->mm))
1810 * Return non-zero if there is a SIGKILL that should be waking us up.
1811 * Called with the siglock held.
1813 static int sigkill_pending(struct task_struct *tsk)
1815 return sigismember(&tsk->pending.signal, SIGKILL) ||
1816 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1820 * This must be called with current->sighand->siglock held.
1822 * This should be the path for all ptrace stops.
1823 * We always set current->last_siginfo while stopped here.
1824 * That makes it a way to test a stopped process for
1825 * being ptrace-stopped vs being job-control-stopped.
1827 * If we actually decide not to stop at all because the tracer
1828 * is gone, we keep current->exit_code unless clear_code.
1830 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1831 __releases(¤t->sighand->siglock)
1832 __acquires(¤t->sighand->siglock)
1834 bool gstop_done = false;
1836 if (arch_ptrace_stop_needed(exit_code, info)) {
1838 * The arch code has something special to do before a
1839 * ptrace stop. This is allowed to block, e.g. for faults
1840 * on user stack pages. We can't keep the siglock while
1841 * calling arch_ptrace_stop, so we must release it now.
1842 * To preserve proper semantics, we must do this before
1843 * any signal bookkeeping like checking group_stop_count.
1844 * Meanwhile, a SIGKILL could come in before we retake the
1845 * siglock. That must prevent us from sleeping in TASK_TRACED.
1846 * So after regaining the lock, we must check for SIGKILL.
1848 spin_unlock_irq(¤t->sighand->siglock);
1849 arch_ptrace_stop(exit_code, info);
1850 spin_lock_irq(¤t->sighand->siglock);
1851 if (sigkill_pending(current))
1856 * We're committing to trapping. TRACED should be visible before
1857 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1858 * Also, transition to TRACED and updates to ->jobctl should be
1859 * atomic with respect to siglock and should be done after the arch
1860 * hook as siglock is released and regrabbed across it.
1862 set_current_state(TASK_TRACED);
1864 current->last_siginfo = info;
1865 current->exit_code = exit_code;
1868 * If @why is CLD_STOPPED, we're trapping to participate in a group
1869 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1870 * across siglock relocks since INTERRUPT was scheduled, PENDING
1871 * could be clear now. We act as if SIGCONT is received after
1872 * TASK_TRACED is entered - ignore it.
1874 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1875 gstop_done = task_participate_group_stop(current);
1877 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1878 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1879 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1880 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1882 /* entering a trap, clear TRAPPING */
1883 task_clear_jobctl_trapping(current);
1885 spin_unlock_irq(¤t->sighand->siglock);
1886 read_lock(&tasklist_lock);
1887 if (may_ptrace_stop()) {
1889 * Notify parents of the stop.
1891 * While ptraced, there are two parents - the ptracer and
1892 * the real_parent of the group_leader. The ptracer should
1893 * know about every stop while the real parent is only
1894 * interested in the completion of group stop. The states
1895 * for the two don't interact with each other. Notify
1896 * separately unless they're gonna be duplicates.
1898 do_notify_parent_cldstop(current, true, why);
1899 if (gstop_done && ptrace_reparented(current))
1900 do_notify_parent_cldstop(current, false, why);
1903 * Don't want to allow preemption here, because
1904 * sys_ptrace() needs this task to be inactive.
1906 * XXX: implement read_unlock_no_resched().
1909 read_unlock(&tasklist_lock);
1910 preempt_enable_no_resched();
1914 * By the time we got the lock, our tracer went away.
1915 * Don't drop the lock yet, another tracer may come.
1917 * If @gstop_done, the ptracer went away between group stop
1918 * completion and here. During detach, it would have set
1919 * JOBCTL_STOP_PENDING on us and we'll re-enter
1920 * TASK_STOPPED in do_signal_stop() on return, so notifying
1921 * the real parent of the group stop completion is enough.
1924 do_notify_parent_cldstop(current, false, why);
1926 __set_current_state(TASK_RUNNING);
1928 current->exit_code = 0;
1929 read_unlock(&tasklist_lock);
1933 * While in TASK_TRACED, we were considered "frozen enough".
1934 * Now that we woke up, it's crucial if we're supposed to be
1935 * frozen that we freeze now before running anything substantial.
1940 * We are back. Now reacquire the siglock before touching
1941 * last_siginfo, so that we are sure to have synchronized with
1942 * any signal-sending on another CPU that wants to examine it.
1944 spin_lock_irq(¤t->sighand->siglock);
1945 current->last_siginfo = NULL;
1947 /* LISTENING can be set only during STOP traps, clear it */
1948 current->jobctl &= ~JOBCTL_LISTENING;
1951 * Queued signals ignored us while we were stopped for tracing.
1952 * So check for any that we should take before resuming user mode.
1953 * This sets TIF_SIGPENDING, but never clears it.
1955 recalc_sigpending_tsk(current);
1958 static void ptrace_do_notify(int signr, int exit_code, int why)
1962 memset(&info, 0, sizeof info);
1963 info.si_signo = signr;
1964 info.si_code = exit_code;
1965 info.si_pid = task_pid_vnr(current);
1966 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1968 /* Let the debugger run. */
1969 ptrace_stop(exit_code, why, 1, &info);
1972 void ptrace_notify(int exit_code)
1974 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1975 if (unlikely(current->task_works))
1978 spin_lock_irq(¤t->sighand->siglock);
1979 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1980 spin_unlock_irq(¤t->sighand->siglock);
1984 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1985 * @signr: signr causing group stop if initiating
1987 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1988 * and participate in it. If already set, participate in the existing
1989 * group stop. If participated in a group stop (and thus slept), %true is
1990 * returned with siglock released.
1992 * If ptraced, this function doesn't handle stop itself. Instead,
1993 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1994 * untouched. The caller must ensure that INTERRUPT trap handling takes
1995 * places afterwards.
1998 * Must be called with @current->sighand->siglock held, which is released
2002 * %false if group stop is already cancelled or ptrace trap is scheduled.
2003 * %true if participated in group stop.
2005 static bool do_signal_stop(int signr)
2006 __releases(¤t->sighand->siglock)
2008 struct signal_struct *sig = current->signal;
2010 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2011 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2012 struct task_struct *t;
2014 /* signr will be recorded in task->jobctl for retries */
2015 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2017 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2018 unlikely(signal_group_exit(sig)))
2021 * There is no group stop already in progress. We must
2024 * While ptraced, a task may be resumed while group stop is
2025 * still in effect and then receive a stop signal and
2026 * initiate another group stop. This deviates from the
2027 * usual behavior as two consecutive stop signals can't
2028 * cause two group stops when !ptraced. That is why we
2029 * also check !task_is_stopped(t) below.
2031 * The condition can be distinguished by testing whether
2032 * SIGNAL_STOP_STOPPED is already set. Don't generate
2033 * group_exit_code in such case.
2035 * This is not necessary for SIGNAL_STOP_CONTINUED because
2036 * an intervening stop signal is required to cause two
2037 * continued events regardless of ptrace.
2039 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2040 sig->group_exit_code = signr;
2042 sig->group_stop_count = 0;
2044 if (task_set_jobctl_pending(current, signr | gstop))
2045 sig->group_stop_count++;
2047 for (t = next_thread(current); t != current;
2048 t = next_thread(t)) {
2050 * Setting state to TASK_STOPPED for a group
2051 * stop is always done with the siglock held,
2052 * so this check has no races.
2054 if (!task_is_stopped(t) &&
2055 task_set_jobctl_pending(t, signr | gstop)) {
2056 sig->group_stop_count++;
2057 if (likely(!(t->ptrace & PT_SEIZED)))
2058 signal_wake_up(t, 0);
2060 ptrace_trap_notify(t);
2065 if (likely(!current->ptrace)) {
2069 * If there are no other threads in the group, or if there
2070 * is a group stop in progress and we are the last to stop,
2071 * report to the parent.
2073 if (task_participate_group_stop(current))
2074 notify = CLD_STOPPED;
2076 __set_current_state(TASK_STOPPED);
2077 spin_unlock_irq(¤t->sighand->siglock);
2080 * Notify the parent of the group stop completion. Because
2081 * we're not holding either the siglock or tasklist_lock
2082 * here, ptracer may attach inbetween; however, this is for
2083 * group stop and should always be delivered to the real
2084 * parent of the group leader. The new ptracer will get
2085 * its notification when this task transitions into
2089 read_lock(&tasklist_lock);
2090 do_notify_parent_cldstop(current, false, notify);
2091 read_unlock(&tasklist_lock);
2094 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2099 * While ptraced, group stop is handled by STOP trap.
2100 * Schedule it and let the caller deal with it.
2102 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2108 * do_jobctl_trap - take care of ptrace jobctl traps
2110 * When PT_SEIZED, it's used for both group stop and explicit
2111 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2112 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2113 * the stop signal; otherwise, %SIGTRAP.
2115 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2116 * number as exit_code and no siginfo.
2119 * Must be called with @current->sighand->siglock held, which may be
2120 * released and re-acquired before returning with intervening sleep.
2122 static void do_jobctl_trap(void)
2124 struct signal_struct *signal = current->signal;
2125 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2127 if (current->ptrace & PT_SEIZED) {
2128 if (!signal->group_stop_count &&
2129 !(signal->flags & SIGNAL_STOP_STOPPED))
2131 WARN_ON_ONCE(!signr);
2132 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2135 WARN_ON_ONCE(!signr);
2136 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2137 current->exit_code = 0;
2141 static int ptrace_signal(int signr, siginfo_t *info)
2143 ptrace_signal_deliver();
2145 * We do not check sig_kernel_stop(signr) but set this marker
2146 * unconditionally because we do not know whether debugger will
2147 * change signr. This flag has no meaning unless we are going
2148 * to stop after return from ptrace_stop(). In this case it will
2149 * be checked in do_signal_stop(), we should only stop if it was
2150 * not cleared by SIGCONT while we were sleeping. See also the
2151 * comment in dequeue_signal().
2153 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2154 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2156 /* We're back. Did the debugger cancel the sig? */
2157 signr = current->exit_code;
2161 current->exit_code = 0;
2164 * Update the siginfo structure if the signal has
2165 * changed. If the debugger wanted something
2166 * specific in the siginfo structure then it should
2167 * have updated *info via PTRACE_SETSIGINFO.
2169 if (signr != info->si_signo) {
2170 info->si_signo = signr;
2172 info->si_code = SI_USER;
2174 info->si_pid = task_pid_vnr(current->parent);
2175 info->si_uid = from_kuid_munged(current_user_ns(),
2176 task_uid(current->parent));
2180 /* If the (new) signal is now blocked, requeue it. */
2181 if (sigismember(¤t->blocked, signr)) {
2182 specific_send_sig_info(signr, info, current);
2189 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2190 struct pt_regs *regs, void *cookie)
2192 struct sighand_struct *sighand = current->sighand;
2193 struct signal_struct *signal = current->signal;
2196 if (unlikely(current->task_works))
2199 if (unlikely(uprobe_deny_signal()))
2204 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2205 * While in TASK_STOPPED, we were considered "frozen enough".
2206 * Now that we woke up, it's crucial if we're supposed to be
2207 * frozen that we freeze now before running anything substantial.
2211 spin_lock_irq(&sighand->siglock);
2213 * Every stopped thread goes here after wakeup. Check to see if
2214 * we should notify the parent, prepare_signal(SIGCONT) encodes
2215 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2217 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2220 if (signal->flags & SIGNAL_CLD_CONTINUED)
2221 why = CLD_CONTINUED;
2225 signal->flags &= ~SIGNAL_CLD_MASK;
2227 spin_unlock_irq(&sighand->siglock);
2230 * Notify the parent that we're continuing. This event is
2231 * always per-process and doesn't make whole lot of sense
2232 * for ptracers, who shouldn't consume the state via
2233 * wait(2) either, but, for backward compatibility, notify
2234 * the ptracer of the group leader too unless it's gonna be
2237 read_lock(&tasklist_lock);
2238 do_notify_parent_cldstop(current, false, why);
2240 if (ptrace_reparented(current->group_leader))
2241 do_notify_parent_cldstop(current->group_leader,
2243 read_unlock(&tasklist_lock);
2249 struct k_sigaction *ka;
2251 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2255 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2257 spin_unlock_irq(&sighand->siglock);
2261 signr = dequeue_signal(current, ¤t->blocked, info);
2264 break; /* will return 0 */
2266 if (unlikely(current->ptrace) && signr != SIGKILL) {
2267 signr = ptrace_signal(signr, info);
2272 ka = &sighand->action[signr-1];
2274 /* Trace actually delivered signals. */
2275 trace_signal_deliver(signr, info, ka);
2277 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2279 if (ka->sa.sa_handler != SIG_DFL) {
2280 /* Run the handler. */
2283 if (ka->sa.sa_flags & SA_ONESHOT)
2284 ka->sa.sa_handler = SIG_DFL;
2286 break; /* will return non-zero "signr" value */
2290 * Now we are doing the default action for this signal.
2292 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2296 * Global init gets no signals it doesn't want.
2297 * Container-init gets no signals it doesn't want from same
2300 * Note that if global/container-init sees a sig_kernel_only()
2301 * signal here, the signal must have been generated internally
2302 * or must have come from an ancestor namespace. In either
2303 * case, the signal cannot be dropped.
2305 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2306 !sig_kernel_only(signr))
2309 if (sig_kernel_stop(signr)) {
2311 * The default action is to stop all threads in
2312 * the thread group. The job control signals
2313 * do nothing in an orphaned pgrp, but SIGSTOP
2314 * always works. Note that siglock needs to be
2315 * dropped during the call to is_orphaned_pgrp()
2316 * because of lock ordering with tasklist_lock.
2317 * This allows an intervening SIGCONT to be posted.
2318 * We need to check for that and bail out if necessary.
2320 if (signr != SIGSTOP) {
2321 spin_unlock_irq(&sighand->siglock);
2323 /* signals can be posted during this window */
2325 if (is_current_pgrp_orphaned())
2328 spin_lock_irq(&sighand->siglock);
2331 if (likely(do_signal_stop(info->si_signo))) {
2332 /* It released the siglock. */
2337 * We didn't actually stop, due to a race
2338 * with SIGCONT or something like that.
2343 spin_unlock_irq(&sighand->siglock);
2346 * Anything else is fatal, maybe with a core dump.
2348 current->flags |= PF_SIGNALED;
2350 if (sig_kernel_coredump(signr)) {
2351 if (print_fatal_signals)
2352 print_fatal_signal(regs, info->si_signo);
2354 * If it was able to dump core, this kills all
2355 * other threads in the group and synchronizes with
2356 * their demise. If we lost the race with another
2357 * thread getting here, it set group_exit_code
2358 * first and our do_group_exit call below will use
2359 * that value and ignore the one we pass it.
2361 do_coredump(info, regs);
2365 * Death signals, no core dump.
2367 do_group_exit(info->si_signo);
2370 spin_unlock_irq(&sighand->siglock);
2375 * signal_delivered -
2376 * @sig: number of signal being delivered
2377 * @info: siginfo_t of signal being delivered
2378 * @ka: sigaction setting that chose the handler
2379 * @regs: user register state
2380 * @stepping: nonzero if debugger single-step or block-step in use
2382 * This function should be called when a signal has succesfully been
2383 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2384 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2385 * is set in @ka->sa.sa_flags. Tracing is notified.
2387 void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2388 struct pt_regs *regs, int stepping)
2392 /* A signal was successfully delivered, and the
2393 saved sigmask was stored on the signal frame,
2394 and will be restored by sigreturn. So we can
2395 simply clear the restore sigmask flag. */
2396 clear_restore_sigmask();
2398 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2399 if (!(ka->sa.sa_flags & SA_NODEFER))
2400 sigaddset(&blocked, sig);
2401 set_current_blocked(&blocked);
2402 tracehook_signal_handler(sig, info, ka, regs, stepping);
2406 * It could be that complete_signal() picked us to notify about the
2407 * group-wide signal. Other threads should be notified now to take
2408 * the shared signals in @which since we will not.
2410 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2413 struct task_struct *t;
2415 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2416 if (sigisemptyset(&retarget))
2420 while_each_thread(tsk, t) {
2421 if (t->flags & PF_EXITING)
2424 if (!has_pending_signals(&retarget, &t->blocked))
2426 /* Remove the signals this thread can handle. */
2427 sigandsets(&retarget, &retarget, &t->blocked);
2429 if (!signal_pending(t))
2430 signal_wake_up(t, 0);
2432 if (sigisemptyset(&retarget))
2437 void exit_signals(struct task_struct *tsk)
2443 * @tsk is about to have PF_EXITING set - lock out users which
2444 * expect stable threadgroup.
2446 threadgroup_change_begin(tsk);
2448 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2449 tsk->flags |= PF_EXITING;
2450 threadgroup_change_end(tsk);
2454 spin_lock_irq(&tsk->sighand->siglock);
2456 * From now this task is not visible for group-wide signals,
2457 * see wants_signal(), do_signal_stop().
2459 tsk->flags |= PF_EXITING;
2461 threadgroup_change_end(tsk);
2463 if (!signal_pending(tsk))
2466 unblocked = tsk->blocked;
2467 signotset(&unblocked);
2468 retarget_shared_pending(tsk, &unblocked);
2470 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2471 task_participate_group_stop(tsk))
2472 group_stop = CLD_STOPPED;
2474 spin_unlock_irq(&tsk->sighand->siglock);
2477 * If group stop has completed, deliver the notification. This
2478 * should always go to the real parent of the group leader.
2480 if (unlikely(group_stop)) {
2481 read_lock(&tasklist_lock);
2482 do_notify_parent_cldstop(tsk, false, group_stop);
2483 read_unlock(&tasklist_lock);
2487 EXPORT_SYMBOL(recalc_sigpending);
2488 EXPORT_SYMBOL_GPL(dequeue_signal);
2489 EXPORT_SYMBOL(flush_signals);
2490 EXPORT_SYMBOL(force_sig);
2491 EXPORT_SYMBOL(send_sig);
2492 EXPORT_SYMBOL(send_sig_info);
2493 EXPORT_SYMBOL(sigprocmask);
2494 EXPORT_SYMBOL(block_all_signals);
2495 EXPORT_SYMBOL(unblock_all_signals);
2499 * System call entry points.
2503 * sys_restart_syscall - restart a system call
2505 SYSCALL_DEFINE0(restart_syscall)
2507 struct restart_block *restart = ¤t_thread_info()->restart_block;
2508 return restart->fn(restart);
2511 long do_no_restart_syscall(struct restart_block *param)
2516 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2518 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2519 sigset_t newblocked;
2520 /* A set of now blocked but previously unblocked signals. */
2521 sigandnsets(&newblocked, newset, ¤t->blocked);
2522 retarget_shared_pending(tsk, &newblocked);
2524 tsk->blocked = *newset;
2525 recalc_sigpending();
2529 * set_current_blocked - change current->blocked mask
2532 * It is wrong to change ->blocked directly, this helper should be used
2533 * to ensure the process can't miss a shared signal we are going to block.
2535 void set_current_blocked(sigset_t *newset)
2537 struct task_struct *tsk = current;
2538 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2539 spin_lock_irq(&tsk->sighand->siglock);
2540 __set_task_blocked(tsk, newset);
2541 spin_unlock_irq(&tsk->sighand->siglock);
2544 void __set_current_blocked(const sigset_t *newset)
2546 struct task_struct *tsk = current;
2548 spin_lock_irq(&tsk->sighand->siglock);
2549 __set_task_blocked(tsk, newset);
2550 spin_unlock_irq(&tsk->sighand->siglock);
2554 * This is also useful for kernel threads that want to temporarily
2555 * (or permanently) block certain signals.
2557 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2558 * interface happily blocks "unblockable" signals like SIGKILL
2561 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2563 struct task_struct *tsk = current;
2566 /* Lockless, only current can change ->blocked, never from irq */
2568 *oldset = tsk->blocked;
2572 sigorsets(&newset, &tsk->blocked, set);
2575 sigandnsets(&newset, &tsk->blocked, set);
2584 __set_current_blocked(&newset);
2589 * sys_rt_sigprocmask - change the list of currently blocked signals
2590 * @how: whether to add, remove, or set signals
2591 * @nset: stores pending signals
2592 * @oset: previous value of signal mask if non-null
2593 * @sigsetsize: size of sigset_t type
2595 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2596 sigset_t __user *, oset, size_t, sigsetsize)
2598 sigset_t old_set, new_set;
2601 /* XXX: Don't preclude handling different sized sigset_t's. */
2602 if (sigsetsize != sizeof(sigset_t))
2605 old_set = current->blocked;
2608 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2610 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2612 error = sigprocmask(how, &new_set, NULL);
2618 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2625 long do_sigpending(void __user *set, unsigned long sigsetsize)
2627 long error = -EINVAL;
2630 if (sigsetsize > sizeof(sigset_t))
2633 spin_lock_irq(¤t->sighand->siglock);
2634 sigorsets(&pending, ¤t->pending.signal,
2635 ¤t->signal->shared_pending.signal);
2636 spin_unlock_irq(¤t->sighand->siglock);
2638 /* Outside the lock because only this thread touches it. */
2639 sigandsets(&pending, ¤t->blocked, &pending);
2642 if (!copy_to_user(set, &pending, sigsetsize))
2650 * sys_rt_sigpending - examine a pending signal that has been raised
2652 * @set: stores pending signals
2653 * @sigsetsize: size of sigset_t type or larger
2655 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2657 return do_sigpending(set, sigsetsize);
2660 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2662 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2666 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2668 if (from->si_code < 0)
2669 return __copy_to_user(to, from, sizeof(siginfo_t))
2672 * If you change siginfo_t structure, please be sure
2673 * this code is fixed accordingly.
2674 * Please remember to update the signalfd_copyinfo() function
2675 * inside fs/signalfd.c too, in case siginfo_t changes.
2676 * It should never copy any pad contained in the structure
2677 * to avoid security leaks, but must copy the generic
2678 * 3 ints plus the relevant union member.
2680 err = __put_user(from->si_signo, &to->si_signo);
2681 err |= __put_user(from->si_errno, &to->si_errno);
2682 err |= __put_user((short)from->si_code, &to->si_code);
2683 switch (from->si_code & __SI_MASK) {
2685 err |= __put_user(from->si_pid, &to->si_pid);
2686 err |= __put_user(from->si_uid, &to->si_uid);
2689 err |= __put_user(from->si_tid, &to->si_tid);
2690 err |= __put_user(from->si_overrun, &to->si_overrun);
2691 err |= __put_user(from->si_ptr, &to->si_ptr);
2694 err |= __put_user(from->si_band, &to->si_band);
2695 err |= __put_user(from->si_fd, &to->si_fd);
2698 err |= __put_user(from->si_addr, &to->si_addr);
2699 #ifdef __ARCH_SI_TRAPNO
2700 err |= __put_user(from->si_trapno, &to->si_trapno);
2702 #ifdef BUS_MCEERR_AO
2704 * Other callers might not initialize the si_lsb field,
2705 * so check explicitly for the right codes here.
2707 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2708 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2712 err |= __put_user(from->si_pid, &to->si_pid);
2713 err |= __put_user(from->si_uid, &to->si_uid);
2714 err |= __put_user(from->si_status, &to->si_status);
2715 err |= __put_user(from->si_utime, &to->si_utime);
2716 err |= __put_user(from->si_stime, &to->si_stime);
2718 case __SI_RT: /* This is not generated by the kernel as of now. */
2719 case __SI_MESGQ: /* But this is */
2720 err |= __put_user(from->si_pid, &to->si_pid);
2721 err |= __put_user(from->si_uid, &to->si_uid);
2722 err |= __put_user(from->si_ptr, &to->si_ptr);
2724 #ifdef __ARCH_SIGSYS
2726 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2727 err |= __put_user(from->si_syscall, &to->si_syscall);
2728 err |= __put_user(from->si_arch, &to->si_arch);
2731 default: /* this is just in case for now ... */
2732 err |= __put_user(from->si_pid, &to->si_pid);
2733 err |= __put_user(from->si_uid, &to->si_uid);
2742 * do_sigtimedwait - wait for queued signals specified in @which
2743 * @which: queued signals to wait for
2744 * @info: if non-null, the signal's siginfo is returned here
2745 * @ts: upper bound on process time suspension
2747 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2748 const struct timespec *ts)
2750 struct task_struct *tsk = current;
2751 long timeout = MAX_SCHEDULE_TIMEOUT;
2752 sigset_t mask = *which;
2756 if (!timespec_valid(ts))
2758 timeout = timespec_to_jiffies(ts);
2760 * We can be close to the next tick, add another one
2761 * to ensure we will wait at least the time asked for.
2763 if (ts->tv_sec || ts->tv_nsec)
2768 * Invert the set of allowed signals to get those we want to block.
2770 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2773 spin_lock_irq(&tsk->sighand->siglock);
2774 sig = dequeue_signal(tsk, &mask, info);
2775 if (!sig && timeout) {
2777 * None ready, temporarily unblock those we're interested
2778 * while we are sleeping in so that we'll be awakened when
2779 * they arrive. Unblocking is always fine, we can avoid
2780 * set_current_blocked().
2782 tsk->real_blocked = tsk->blocked;
2783 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2784 recalc_sigpending();
2785 spin_unlock_irq(&tsk->sighand->siglock);
2787 timeout = schedule_timeout_interruptible(timeout);
2789 spin_lock_irq(&tsk->sighand->siglock);
2790 __set_task_blocked(tsk, &tsk->real_blocked);
2791 siginitset(&tsk->real_blocked, 0);
2792 sig = dequeue_signal(tsk, &mask, info);
2794 spin_unlock_irq(&tsk->sighand->siglock);
2798 return timeout ? -EINTR : -EAGAIN;
2802 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2804 * @uthese: queued signals to wait for
2805 * @uinfo: if non-null, the signal's siginfo is returned here
2806 * @uts: upper bound on process time suspension
2807 * @sigsetsize: size of sigset_t type
2809 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2810 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2818 /* XXX: Don't preclude handling different sized sigset_t's. */
2819 if (sigsetsize != sizeof(sigset_t))
2822 if (copy_from_user(&these, uthese, sizeof(these)))
2826 if (copy_from_user(&ts, uts, sizeof(ts)))
2830 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2832 if (ret > 0 && uinfo) {
2833 if (copy_siginfo_to_user(uinfo, &info))
2841 * sys_kill - send a signal to a process
2842 * @pid: the PID of the process
2843 * @sig: signal to be sent
2845 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2847 struct siginfo info;
2849 info.si_signo = sig;
2851 info.si_code = SI_USER;
2852 info.si_pid = task_tgid_vnr(current);
2853 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2855 return kill_something_info(sig, &info, pid);
2859 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2861 struct task_struct *p;
2865 p = find_task_by_vpid(pid);
2866 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2867 error = check_kill_permission(sig, info, p);
2869 * The null signal is a permissions and process existence
2870 * probe. No signal is actually delivered.
2872 if (!error && sig) {
2873 error = do_send_sig_info(sig, info, p, false);
2875 * If lock_task_sighand() failed we pretend the task
2876 * dies after receiving the signal. The window is tiny,
2877 * and the signal is private anyway.
2879 if (unlikely(error == -ESRCH))
2888 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2890 struct siginfo info;
2892 info.si_signo = sig;
2894 info.si_code = SI_TKILL;
2895 info.si_pid = task_tgid_vnr(current);
2896 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2898 return do_send_specific(tgid, pid, sig, &info);
2902 * sys_tgkill - send signal to one specific thread
2903 * @tgid: the thread group ID of the thread
2904 * @pid: the PID of the thread
2905 * @sig: signal to be sent
2907 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2908 * exists but it's not belonging to the target process anymore. This
2909 * method solves the problem of threads exiting and PIDs getting reused.
2911 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2913 /* This is only valid for single tasks */
2914 if (pid <= 0 || tgid <= 0)
2917 return do_tkill(tgid, pid, sig);
2921 * sys_tkill - send signal to one specific task
2922 * @pid: the PID of the task
2923 * @sig: signal to be sent
2925 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2927 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2929 /* This is only valid for single tasks */
2933 return do_tkill(0, pid, sig);
2937 * sys_rt_sigqueueinfo - send signal information to a signal
2938 * @pid: the PID of the thread
2939 * @sig: signal to be sent
2940 * @uinfo: signal info to be sent
2942 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2943 siginfo_t __user *, uinfo)
2947 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2950 /* Not even root can pretend to send signals from the kernel.
2951 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2953 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2954 /* We used to allow any < 0 si_code */
2955 WARN_ON_ONCE(info.si_code < 0);
2958 info.si_signo = sig;
2960 /* POSIX.1b doesn't mention process groups. */
2961 return kill_proc_info(sig, &info, pid);
2964 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2966 /* This is only valid for single tasks */
2967 if (pid <= 0 || tgid <= 0)
2970 /* Not even root can pretend to send signals from the kernel.
2971 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2973 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2974 /* We used to allow any < 0 si_code */
2975 WARN_ON_ONCE(info->si_code < 0);
2978 info->si_signo = sig;
2980 return do_send_specific(tgid, pid, sig, info);
2983 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2984 siginfo_t __user *, uinfo)
2988 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2991 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2994 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2996 struct task_struct *t = current;
2997 struct k_sigaction *k;
3000 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3003 k = &t->sighand->action[sig-1];
3005 spin_lock_irq(¤t->sighand->siglock);
3010 sigdelsetmask(&act->sa.sa_mask,
3011 sigmask(SIGKILL) | sigmask(SIGSTOP));
3015 * "Setting a signal action to SIG_IGN for a signal that is
3016 * pending shall cause the pending signal to be discarded,
3017 * whether or not it is blocked."
3019 * "Setting a signal action to SIG_DFL for a signal that is
3020 * pending and whose default action is to ignore the signal
3021 * (for example, SIGCHLD), shall cause the pending signal to
3022 * be discarded, whether or not it is blocked"
3024 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3026 sigaddset(&mask, sig);
3027 rm_from_queue_full(&mask, &t->signal->shared_pending);
3029 rm_from_queue_full(&mask, &t->pending);
3031 } while (t != current);
3035 spin_unlock_irq(¤t->sighand->siglock);
3040 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3045 oss.ss_sp = (void __user *) current->sas_ss_sp;
3046 oss.ss_size = current->sas_ss_size;
3047 oss.ss_flags = sas_ss_flags(sp);
3055 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3057 error = __get_user(ss_sp, &uss->ss_sp) |
3058 __get_user(ss_flags, &uss->ss_flags) |
3059 __get_user(ss_size, &uss->ss_size);
3064 if (on_sig_stack(sp))
3069 * Note - this code used to test ss_flags incorrectly:
3070 * old code may have been written using ss_flags==0
3071 * to mean ss_flags==SS_ONSTACK (as this was the only
3072 * way that worked) - this fix preserves that older
3075 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3078 if (ss_flags == SS_DISABLE) {
3083 if (ss_size < MINSIGSTKSZ)
3087 current->sas_ss_sp = (unsigned long) ss_sp;
3088 current->sas_ss_size = ss_size;
3094 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3096 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3097 __put_user(oss.ss_size, &uoss->ss_size) |
3098 __put_user(oss.ss_flags, &uoss->ss_flags);
3105 #ifdef __ARCH_WANT_SYS_SIGPENDING
3108 * sys_sigpending - examine pending signals
3109 * @set: where mask of pending signal is returned
3111 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3113 return do_sigpending(set, sizeof(*set));
3118 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3120 * sys_sigprocmask - examine and change blocked signals
3121 * @how: whether to add, remove, or set signals
3122 * @nset: signals to add or remove (if non-null)
3123 * @oset: previous value of signal mask if non-null
3125 * Some platforms have their own version with special arguments;
3126 * others support only sys_rt_sigprocmask.
3129 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3130 old_sigset_t __user *, oset)
3132 old_sigset_t old_set, new_set;
3133 sigset_t new_blocked;
3135 old_set = current->blocked.sig[0];
3138 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3140 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3142 new_blocked = current->blocked;
3146 sigaddsetmask(&new_blocked, new_set);
3149 sigdelsetmask(&new_blocked, new_set);
3152 new_blocked.sig[0] = new_set;
3158 __set_current_blocked(&new_blocked);
3162 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3168 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3170 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3172 * sys_rt_sigaction - alter an action taken by a process
3173 * @sig: signal to be sent
3174 * @act: new sigaction
3175 * @oact: used to save the previous sigaction
3176 * @sigsetsize: size of sigset_t type
3178 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3179 const struct sigaction __user *, act,
3180 struct sigaction __user *, oact,
3183 struct k_sigaction new_sa, old_sa;
3186 /* XXX: Don't preclude handling different sized sigset_t's. */
3187 if (sigsetsize != sizeof(sigset_t))
3191 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3195 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3198 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3204 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3206 #ifdef __ARCH_WANT_SYS_SGETMASK
3209 * For backwards compatibility. Functionality superseded by sigprocmask.
3211 SYSCALL_DEFINE0(sgetmask)
3214 return current->blocked.sig[0];
3217 SYSCALL_DEFINE1(ssetmask, int, newmask)
3219 int old = current->blocked.sig[0];
3222 set_current_blocked(&newset);
3226 #endif /* __ARCH_WANT_SGETMASK */
3228 #ifdef __ARCH_WANT_SYS_SIGNAL
3230 * For backwards compatibility. Functionality superseded by sigaction.
3232 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3234 struct k_sigaction new_sa, old_sa;
3237 new_sa.sa.sa_handler = handler;
3238 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3239 sigemptyset(&new_sa.sa.sa_mask);
3241 ret = do_sigaction(sig, &new_sa, &old_sa);
3243 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3245 #endif /* __ARCH_WANT_SYS_SIGNAL */
3247 #ifdef __ARCH_WANT_SYS_PAUSE
3249 SYSCALL_DEFINE0(pause)
3251 while (!signal_pending(current)) {
3252 current->state = TASK_INTERRUPTIBLE;
3255 return -ERESTARTNOHAND;
3260 int sigsuspend(sigset_t *set)
3262 current->saved_sigmask = current->blocked;
3263 set_current_blocked(set);
3265 current->state = TASK_INTERRUPTIBLE;
3267 set_restore_sigmask();
3268 return -ERESTARTNOHAND;
3271 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3273 * sys_rt_sigsuspend - replace the signal mask for a value with the
3274 * @unewset value until a signal is received
3275 * @unewset: new signal mask value
3276 * @sigsetsize: size of sigset_t type
3278 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3282 /* XXX: Don't preclude handling different sized sigset_t's. */
3283 if (sigsetsize != sizeof(sigset_t))
3286 if (copy_from_user(&newset, unewset, sizeof(newset)))
3288 return sigsuspend(&newset);
3290 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3292 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3297 void __init signals_init(void)
3299 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3302 #ifdef CONFIG_KGDB_KDB
3303 #include <linux/kdb.h>
3305 * kdb_send_sig_info - Allows kdb to send signals without exposing
3306 * signal internals. This function checks if the required locks are
3307 * available before calling the main signal code, to avoid kdb
3311 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3313 static struct task_struct *kdb_prev_t;
3315 if (!spin_trylock(&t->sighand->siglock)) {
3316 kdb_printf("Can't do kill command now.\n"
3317 "The sigmask lock is held somewhere else in "
3318 "kernel, try again later\n");
3321 spin_unlock(&t->sighand->siglock);
3322 new_t = kdb_prev_t != t;
3324 if (t->state != TASK_RUNNING && new_t) {
3325 kdb_printf("Process is not RUNNING, sending a signal from "
3326 "kdb risks deadlock\n"
3327 "on the run queue locks. "
3328 "The signal has _not_ been sent.\n"
3329 "Reissue the kill command if you want to risk "
3333 sig = info->si_signo;
3334 if (send_sig_info(sig, info, t))
3335 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3338 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3340 #endif /* CONFIG_KGDB_KDB */