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 #include <linux/compat.h>
35 #define CREATE_TRACE_POINTS
36 #include <trace/events/signal.h>
38 #include <asm/param.h>
39 #include <asm/uaccess.h>
40 #include <asm/unistd.h>
41 #include <asm/siginfo.h>
42 #include <asm/cacheflush.h>
43 #include "audit.h" /* audit_signal_info() */
46 * SLAB caches for signal bits.
49 static struct kmem_cache *sigqueue_cachep;
51 int print_fatal_signals __read_mostly;
53 static void __user *sig_handler(struct task_struct *t, int sig)
55 return t->sighand->action[sig - 1].sa.sa_handler;
58 static int sig_handler_ignored(void __user *handler, int sig)
60 /* Is it explicitly or implicitly ignored? */
61 return handler == SIG_IGN ||
62 (handler == SIG_DFL && sig_kernel_ignore(sig));
65 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69 handler = sig_handler(t, sig);
71 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
72 handler == SIG_DFL && !force)
75 return sig_handler_ignored(handler, sig);
78 static int sig_ignored(struct task_struct *t, int sig, bool force)
81 * Blocked signals are never ignored, since the
82 * signal handler may change by the time it is
85 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
88 if (!sig_task_ignored(t, sig, force))
92 * Tracers may want to know about even ignored signals.
98 * Re-calculate pending state from the set of locally pending
99 * signals, globally pending signals, and blocked signals.
101 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
106 switch (_NSIG_WORDS) {
108 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
109 ready |= signal->sig[i] &~ blocked->sig[i];
112 case 4: ready = signal->sig[3] &~ blocked->sig[3];
113 ready |= signal->sig[2] &~ blocked->sig[2];
114 ready |= signal->sig[1] &~ blocked->sig[1];
115 ready |= signal->sig[0] &~ blocked->sig[0];
118 case 2: ready = signal->sig[1] &~ blocked->sig[1];
119 ready |= signal->sig[0] &~ blocked->sig[0];
122 case 1: ready = signal->sig[0] &~ blocked->sig[0];
127 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
129 static int recalc_sigpending_tsk(struct task_struct *t)
131 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
132 PENDING(&t->pending, &t->blocked) ||
133 PENDING(&t->signal->shared_pending, &t->blocked)) {
134 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 * We must never clear the flag in another thread, or in current
139 * when it's possible the current syscall is returning -ERESTART*.
140 * So we don't clear it here, and only callers who know they should do.
146 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
147 * This is superfluous when called on current, the wakeup is a harmless no-op.
149 void recalc_sigpending_and_wake(struct task_struct *t)
151 if (recalc_sigpending_tsk(t))
152 signal_wake_up(t, 0);
155 void recalc_sigpending(void)
157 if (!recalc_sigpending_tsk(current) && !freezing(current))
158 clear_thread_flag(TIF_SIGPENDING);
162 /* Given the mask, find the first available signal that should be serviced. */
164 #define SYNCHRONOUS_MASK \
165 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
166 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
168 int next_signal(struct sigpending *pending, sigset_t *mask)
170 unsigned long i, *s, *m, x;
173 s = pending->signal.sig;
177 * Handle the first word specially: it contains the
178 * synchronous signals that need to be dequeued first.
182 if (x & SYNCHRONOUS_MASK)
183 x &= SYNCHRONOUS_MASK;
188 switch (_NSIG_WORDS) {
190 for (i = 1; i < _NSIG_WORDS; ++i) {
194 sig = ffz(~x) + i*_NSIG_BPW + 1;
203 sig = ffz(~x) + _NSIG_BPW + 1;
214 static inline void print_dropped_signal(int sig)
216 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
218 if (!print_fatal_signals)
221 if (!__ratelimit(&ratelimit_state))
224 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
225 current->comm, current->pid, sig);
229 * task_set_jobctl_pending - set jobctl pending bits
231 * @mask: pending bits to set
233 * Clear @mask from @task->jobctl. @mask must be subset of
234 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
235 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
236 * cleared. If @task is already being killed or exiting, this function
240 * Must be called with @task->sighand->siglock held.
243 * %true if @mask is set, %false if made noop because @task was dying.
245 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
247 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
248 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
249 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
251 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
254 if (mask & JOBCTL_STOP_SIGMASK)
255 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
257 task->jobctl |= mask;
262 * task_clear_jobctl_trapping - clear jobctl trapping bit
265 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
266 * Clear it and wake up the ptracer. Note that we don't need any further
267 * locking. @task->siglock guarantees that @task->parent points to the
271 * Must be called with @task->sighand->siglock held.
273 void task_clear_jobctl_trapping(struct task_struct *task)
275 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
276 task->jobctl &= ~JOBCTL_TRAPPING;
277 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
282 * task_clear_jobctl_pending - clear jobctl pending bits
284 * @mask: pending bits to clear
286 * Clear @mask from @task->jobctl. @mask must be subset of
287 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
288 * STOP bits are cleared together.
290 * If clearing of @mask leaves no stop or trap pending, this function calls
291 * task_clear_jobctl_trapping().
294 * Must be called with @task->sighand->siglock held.
296 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
298 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
300 if (mask & JOBCTL_STOP_PENDING)
301 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
303 task->jobctl &= ~mask;
305 if (!(task->jobctl & JOBCTL_PENDING_MASK))
306 task_clear_jobctl_trapping(task);
310 * task_participate_group_stop - participate in a group stop
311 * @task: task participating in a group stop
313 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
314 * Group stop states are cleared and the group stop count is consumed if
315 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
316 * stop, the appropriate %SIGNAL_* flags are set.
319 * Must be called with @task->sighand->siglock held.
322 * %true if group stop completion should be notified to the parent, %false
325 static bool task_participate_group_stop(struct task_struct *task)
327 struct signal_struct *sig = task->signal;
328 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
330 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
332 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
337 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
338 sig->group_stop_count--;
341 * Tell the caller to notify completion iff we are entering into a
342 * fresh group stop. Read comment in do_signal_stop() for details.
344 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
345 sig->flags = SIGNAL_STOP_STOPPED;
352 * allocate a new signal queue record
353 * - this may be called without locks if and only if t == current, otherwise an
354 * appropriate lock must be held to stop the target task from exiting
356 static struct sigqueue *
357 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
359 struct sigqueue *q = NULL;
360 struct user_struct *user;
363 * Protect access to @t credentials. This can go away when all
364 * callers hold rcu read lock.
367 user = get_uid(__task_cred(t)->user);
368 atomic_inc(&user->sigpending);
371 if (override_rlimit ||
372 atomic_read(&user->sigpending) <=
373 task_rlimit(t, RLIMIT_SIGPENDING)) {
374 q = kmem_cache_alloc(sigqueue_cachep, flags);
376 print_dropped_signal(sig);
379 if (unlikely(q == NULL)) {
380 atomic_dec(&user->sigpending);
383 INIT_LIST_HEAD(&q->list);
391 static void __sigqueue_free(struct sigqueue *q)
393 if (q->flags & SIGQUEUE_PREALLOC)
395 atomic_dec(&q->user->sigpending);
397 kmem_cache_free(sigqueue_cachep, q);
400 void flush_sigqueue(struct sigpending *queue)
404 sigemptyset(&queue->signal);
405 while (!list_empty(&queue->list)) {
406 q = list_entry(queue->list.next, struct sigqueue , list);
407 list_del_init(&q->list);
413 * Flush all pending signals for a task.
415 void __flush_signals(struct task_struct *t)
417 clear_tsk_thread_flag(t, TIF_SIGPENDING);
418 flush_sigqueue(&t->pending);
419 flush_sigqueue(&t->signal->shared_pending);
422 void flush_signals(struct task_struct *t)
426 spin_lock_irqsave(&t->sighand->siglock, flags);
428 spin_unlock_irqrestore(&t->sighand->siglock, flags);
431 static void __flush_itimer_signals(struct sigpending *pending)
433 sigset_t signal, retain;
434 struct sigqueue *q, *n;
436 signal = pending->signal;
437 sigemptyset(&retain);
439 list_for_each_entry_safe(q, n, &pending->list, list) {
440 int sig = q->info.si_signo;
442 if (likely(q->info.si_code != SI_TIMER)) {
443 sigaddset(&retain, sig);
445 sigdelset(&signal, sig);
446 list_del_init(&q->list);
451 sigorsets(&pending->signal, &signal, &retain);
454 void flush_itimer_signals(void)
456 struct task_struct *tsk = current;
459 spin_lock_irqsave(&tsk->sighand->siglock, flags);
460 __flush_itimer_signals(&tsk->pending);
461 __flush_itimer_signals(&tsk->signal->shared_pending);
462 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
465 void ignore_signals(struct task_struct *t)
469 for (i = 0; i < _NSIG; ++i)
470 t->sighand->action[i].sa.sa_handler = SIG_IGN;
476 * Flush all handlers for a task.
480 flush_signal_handlers(struct task_struct *t, int force_default)
483 struct k_sigaction *ka = &t->sighand->action[0];
484 for (i = _NSIG ; i != 0 ; i--) {
485 if (force_default || ka->sa.sa_handler != SIG_IGN)
486 ka->sa.sa_handler = SIG_DFL;
488 sigemptyset(&ka->sa.sa_mask);
493 int unhandled_signal(struct task_struct *tsk, int sig)
495 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
496 if (is_global_init(tsk))
498 if (handler != SIG_IGN && handler != SIG_DFL)
500 /* if ptraced, let the tracer determine */
505 * Notify the system that a driver wants to block all signals for this
506 * process, and wants to be notified if any signals at all were to be
507 * sent/acted upon. If the notifier routine returns non-zero, then the
508 * signal will be acted upon after all. If the notifier routine returns 0,
509 * then then signal will be blocked. Only one block per process is
510 * allowed. priv is a pointer to private data that the notifier routine
511 * can use to determine if the signal should be blocked or not.
514 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
518 spin_lock_irqsave(¤t->sighand->siglock, flags);
519 current->notifier_mask = mask;
520 current->notifier_data = priv;
521 current->notifier = notifier;
522 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
525 /* Notify the system that blocking has ended. */
528 unblock_all_signals(void)
532 spin_lock_irqsave(¤t->sighand->siglock, flags);
533 current->notifier = NULL;
534 current->notifier_data = NULL;
536 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
539 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
541 struct sigqueue *q, *first = NULL;
544 * Collect the siginfo appropriate to this signal. Check if
545 * there is another siginfo for the same signal.
547 list_for_each_entry(q, &list->list, list) {
548 if (q->info.si_signo == sig) {
555 sigdelset(&list->signal, sig);
559 list_del_init(&first->list);
560 copy_siginfo(info, &first->info);
561 __sigqueue_free(first);
564 * Ok, it wasn't in the queue. This must be
565 * a fast-pathed signal or we must have been
566 * out of queue space. So zero out the info.
568 info->si_signo = sig;
570 info->si_code = SI_USER;
576 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
579 int sig = next_signal(pending, mask);
582 if (current->notifier) {
583 if (sigismember(current->notifier_mask, sig)) {
584 if (!(current->notifier)(current->notifier_data)) {
585 clear_thread_flag(TIF_SIGPENDING);
591 collect_signal(sig, pending, info);
598 * Dequeue a signal and return the element to the caller, which is
599 * expected to free it.
601 * All callers have to hold the siglock.
603 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
607 /* We only dequeue private signals from ourselves, we don't let
608 * signalfd steal them
610 signr = __dequeue_signal(&tsk->pending, mask, info);
612 signr = __dequeue_signal(&tsk->signal->shared_pending,
617 * itimers are process shared and we restart periodic
618 * itimers in the signal delivery path to prevent DoS
619 * attacks in the high resolution timer case. This is
620 * compliant with the old way of self-restarting
621 * itimers, as the SIGALRM is a legacy signal and only
622 * queued once. Changing the restart behaviour to
623 * restart the timer in the signal dequeue path is
624 * reducing the timer noise on heavy loaded !highres
627 if (unlikely(signr == SIGALRM)) {
628 struct hrtimer *tmr = &tsk->signal->real_timer;
630 if (!hrtimer_is_queued(tmr) &&
631 tsk->signal->it_real_incr.tv64 != 0) {
632 hrtimer_forward(tmr, tmr->base->get_time(),
633 tsk->signal->it_real_incr);
634 hrtimer_restart(tmr);
643 if (unlikely(sig_kernel_stop(signr))) {
645 * Set a marker that we have dequeued a stop signal. Our
646 * caller might release the siglock and then the pending
647 * stop signal it is about to process is no longer in the
648 * pending bitmasks, but must still be cleared by a SIGCONT
649 * (and overruled by a SIGKILL). So those cases clear this
650 * shared flag after we've set it. Note that this flag may
651 * remain set after the signal we return is ignored or
652 * handled. That doesn't matter because its only purpose
653 * is to alert stop-signal processing code when another
654 * processor has come along and cleared the flag.
656 current->jobctl |= JOBCTL_STOP_DEQUEUED;
658 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
660 * Release the siglock to ensure proper locking order
661 * of timer locks outside of siglocks. Note, we leave
662 * irqs disabled here, since the posix-timers code is
663 * about to disable them again anyway.
665 spin_unlock(&tsk->sighand->siglock);
666 do_schedule_next_timer(info);
667 spin_lock(&tsk->sighand->siglock);
673 * Tell a process that it has a new active signal..
675 * NOTE! we rely on the previous spin_lock to
676 * lock interrupts for us! We can only be called with
677 * "siglock" held, and the local interrupt must
678 * have been disabled when that got acquired!
680 * No need to set need_resched since signal event passing
681 * goes through ->blocked
683 void signal_wake_up(struct task_struct *t, int resume)
687 set_tsk_thread_flag(t, TIF_SIGPENDING);
690 * For SIGKILL, we want to wake it up in the stopped/traced/killable
691 * case. We don't check t->state here because there is a race with it
692 * executing another processor and just now entering stopped state.
693 * By using wake_up_state, we ensure the process will wake up and
694 * handle its death signal.
696 mask = TASK_INTERRUPTIBLE;
698 mask |= TASK_WAKEKILL;
699 if (!wake_up_state(t, mask))
704 * Remove signals in mask from the pending set and queue.
705 * Returns 1 if any signals were found.
707 * All callers must be holding the siglock.
709 * This version takes a sigset mask and looks at all signals,
710 * not just those in the first mask word.
712 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
714 struct sigqueue *q, *n;
717 sigandsets(&m, mask, &s->signal);
718 if (sigisemptyset(&m))
721 sigandnsets(&s->signal, &s->signal, mask);
722 list_for_each_entry_safe(q, n, &s->list, list) {
723 if (sigismember(mask, q->info.si_signo)) {
724 list_del_init(&q->list);
731 * Remove signals in mask from the pending set and queue.
732 * Returns 1 if any signals were found.
734 * All callers must be holding the siglock.
736 static int rm_from_queue(unsigned long mask, struct sigpending *s)
738 struct sigqueue *q, *n;
740 if (!sigtestsetmask(&s->signal, mask))
743 sigdelsetmask(&s->signal, mask);
744 list_for_each_entry_safe(q, n, &s->list, list) {
745 if (q->info.si_signo < SIGRTMIN &&
746 (mask & sigmask(q->info.si_signo))) {
747 list_del_init(&q->list);
754 static inline int is_si_special(const struct siginfo *info)
756 return info <= SEND_SIG_FORCED;
759 static inline bool si_fromuser(const struct siginfo *info)
761 return info == SEND_SIG_NOINFO ||
762 (!is_si_special(info) && SI_FROMUSER(info));
766 * called with RCU read lock from check_kill_permission()
768 static int kill_ok_by_cred(struct task_struct *t)
770 const struct cred *cred = current_cred();
771 const struct cred *tcred = __task_cred(t);
773 if (uid_eq(cred->euid, tcred->suid) ||
774 uid_eq(cred->euid, tcred->uid) ||
775 uid_eq(cred->uid, tcred->suid) ||
776 uid_eq(cred->uid, tcred->uid))
779 if (ns_capable(tcred->user_ns, CAP_KILL))
786 * Bad permissions for sending the signal
787 * - the caller must hold the RCU read lock
789 static int check_kill_permission(int sig, struct siginfo *info,
790 struct task_struct *t)
795 if (!valid_signal(sig))
798 if (!si_fromuser(info))
801 error = audit_signal_info(sig, t); /* Let audit system see the signal */
805 if (!same_thread_group(current, t) &&
806 !kill_ok_by_cred(t)) {
809 sid = task_session(t);
811 * We don't return the error if sid == NULL. The
812 * task was unhashed, the caller must notice this.
814 if (!sid || sid == task_session(current))
821 return security_task_kill(t, info, sig, 0);
825 * ptrace_trap_notify - schedule trap to notify ptracer
826 * @t: tracee wanting to notify tracer
828 * This function schedules sticky ptrace trap which is cleared on the next
829 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
832 * If @t is running, STOP trap will be taken. If trapped for STOP and
833 * ptracer is listening for events, tracee is woken up so that it can
834 * re-trap for the new event. If trapped otherwise, STOP trap will be
835 * eventually taken without returning to userland after the existing traps
836 * are finished by PTRACE_CONT.
839 * Must be called with @task->sighand->siglock held.
841 static void ptrace_trap_notify(struct task_struct *t)
843 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
844 assert_spin_locked(&t->sighand->siglock);
846 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
847 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
851 * Handle magic process-wide effects of stop/continue signals. Unlike
852 * the signal actions, these happen immediately at signal-generation
853 * time regardless of blocking, ignoring, or handling. This does the
854 * actual continuing for SIGCONT, but not the actual stopping for stop
855 * signals. The process stop is done as a signal action for SIG_DFL.
857 * Returns true if the signal should be actually delivered, otherwise
858 * it should be dropped.
860 static int prepare_signal(int sig, struct task_struct *p, bool force)
862 struct signal_struct *signal = p->signal;
863 struct task_struct *t;
865 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
867 * The process is in the middle of dying, nothing to do.
869 } else if (sig_kernel_stop(sig)) {
871 * This is a stop signal. Remove SIGCONT from all queues.
873 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
876 rm_from_queue(sigmask(SIGCONT), &t->pending);
877 } while_each_thread(p, t);
878 } else if (sig == SIGCONT) {
881 * Remove all stop signals from all queues, wake all threads.
883 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
886 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
887 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
888 if (likely(!(t->ptrace & PT_SEIZED)))
889 wake_up_state(t, __TASK_STOPPED);
891 ptrace_trap_notify(t);
892 } while_each_thread(p, t);
895 * Notify the parent with CLD_CONTINUED if we were stopped.
897 * If we were in the middle of a group stop, we pretend it
898 * was already finished, and then continued. Since SIGCHLD
899 * doesn't queue we report only CLD_STOPPED, as if the next
900 * CLD_CONTINUED was dropped.
903 if (signal->flags & SIGNAL_STOP_STOPPED)
904 why |= SIGNAL_CLD_CONTINUED;
905 else if (signal->group_stop_count)
906 why |= SIGNAL_CLD_STOPPED;
910 * The first thread which returns from do_signal_stop()
911 * will take ->siglock, notice SIGNAL_CLD_MASK, and
912 * notify its parent. See get_signal_to_deliver().
914 signal->flags = why | SIGNAL_STOP_CONTINUED;
915 signal->group_stop_count = 0;
916 signal->group_exit_code = 0;
920 return !sig_ignored(p, sig, force);
924 * Test if P wants to take SIG. After we've checked all threads with this,
925 * it's equivalent to finding no threads not blocking SIG. Any threads not
926 * blocking SIG were ruled out because they are not running and already
927 * have pending signals. Such threads will dequeue from the shared queue
928 * as soon as they're available, so putting the signal on the shared queue
929 * will be equivalent to sending it to one such thread.
931 static inline int wants_signal(int sig, struct task_struct *p)
933 if (sigismember(&p->blocked, sig))
935 if (p->flags & PF_EXITING)
939 if (task_is_stopped_or_traced(p))
941 return task_curr(p) || !signal_pending(p);
944 static void complete_signal(int sig, struct task_struct *p, int group)
946 struct signal_struct *signal = p->signal;
947 struct task_struct *t;
950 * Now find a thread we can wake up to take the signal off the queue.
952 * If the main thread wants the signal, it gets first crack.
953 * Probably the least surprising to the average bear.
955 if (wants_signal(sig, p))
957 else if (!group || thread_group_empty(p))
959 * There is just one thread and it does not need to be woken.
960 * It will dequeue unblocked signals before it runs again.
965 * Otherwise try to find a suitable thread.
967 t = signal->curr_target;
968 while (!wants_signal(sig, t)) {
970 if (t == signal->curr_target)
972 * No thread needs to be woken.
973 * Any eligible threads will see
974 * the signal in the queue soon.
978 signal->curr_target = t;
982 * Found a killable thread. If the signal will be fatal,
983 * then start taking the whole group down immediately.
985 if (sig_fatal(p, sig) &&
986 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
987 !sigismember(&t->real_blocked, sig) &&
988 (sig == SIGKILL || !t->ptrace)) {
990 * This signal will be fatal to the whole group.
992 if (!sig_kernel_coredump(sig)) {
994 * Start a group exit and wake everybody up.
995 * This way we don't have other threads
996 * running and doing things after a slower
997 * thread has the fatal signal pending.
999 signal->flags = SIGNAL_GROUP_EXIT;
1000 signal->group_exit_code = sig;
1001 signal->group_stop_count = 0;
1004 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1005 sigaddset(&t->pending.signal, SIGKILL);
1006 signal_wake_up(t, 1);
1007 } while_each_thread(p, t);
1013 * The signal is already in the shared-pending queue.
1014 * Tell the chosen thread to wake up and dequeue it.
1016 signal_wake_up(t, sig == SIGKILL);
1020 static inline int legacy_queue(struct sigpending *signals, int sig)
1022 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1025 #ifdef CONFIG_USER_NS
1026 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1028 if (current_user_ns() == task_cred_xxx(t, user_ns))
1031 if (SI_FROMKERNEL(info))
1035 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1036 make_kuid(current_user_ns(), info->si_uid));
1040 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1046 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1047 int group, int from_ancestor_ns)
1049 struct sigpending *pending;
1051 int override_rlimit;
1052 int ret = 0, result;
1054 assert_spin_locked(&t->sighand->siglock);
1056 result = TRACE_SIGNAL_IGNORED;
1057 if (!prepare_signal(sig, t,
1058 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1061 pending = group ? &t->signal->shared_pending : &t->pending;
1063 * Short-circuit ignored signals and support queuing
1064 * exactly one non-rt signal, so that we can get more
1065 * detailed information about the cause of the signal.
1067 result = TRACE_SIGNAL_ALREADY_PENDING;
1068 if (legacy_queue(pending, sig))
1071 result = TRACE_SIGNAL_DELIVERED;
1073 * fast-pathed signals for kernel-internal things like SIGSTOP
1076 if (info == SEND_SIG_FORCED)
1080 * Real-time signals must be queued if sent by sigqueue, or
1081 * some other real-time mechanism. It is implementation
1082 * defined whether kill() does so. We attempt to do so, on
1083 * the principle of least surprise, but since kill is not
1084 * allowed to fail with EAGAIN when low on memory we just
1085 * make sure at least one signal gets delivered and don't
1086 * pass on the info struct.
1089 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1091 override_rlimit = 0;
1093 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1096 list_add_tail(&q->list, &pending->list);
1097 switch ((unsigned long) info) {
1098 case (unsigned long) SEND_SIG_NOINFO:
1099 q->info.si_signo = sig;
1100 q->info.si_errno = 0;
1101 q->info.si_code = SI_USER;
1102 q->info.si_pid = task_tgid_nr_ns(current,
1103 task_active_pid_ns(t));
1104 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1106 case (unsigned long) SEND_SIG_PRIV:
1107 q->info.si_signo = sig;
1108 q->info.si_errno = 0;
1109 q->info.si_code = SI_KERNEL;
1114 copy_siginfo(&q->info, info);
1115 if (from_ancestor_ns)
1120 userns_fixup_signal_uid(&q->info, t);
1122 } else if (!is_si_special(info)) {
1123 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1125 * Queue overflow, abort. We may abort if the
1126 * signal was rt and sent by user using something
1127 * other than kill().
1129 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1134 * This is a silent loss of information. We still
1135 * send the signal, but the *info bits are lost.
1137 result = TRACE_SIGNAL_LOSE_INFO;
1142 signalfd_notify(t, sig);
1143 sigaddset(&pending->signal, sig);
1144 complete_signal(sig, t, group);
1146 trace_signal_generate(sig, info, t, group, result);
1150 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1153 int from_ancestor_ns = 0;
1155 #ifdef CONFIG_PID_NS
1156 from_ancestor_ns = si_fromuser(info) &&
1157 !task_pid_nr_ns(current, task_active_pid_ns(t));
1160 return __send_signal(sig, info, t, group, from_ancestor_ns);
1163 static void print_fatal_signal(int signr)
1165 struct pt_regs *regs = signal_pt_regs();
1166 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1167 current->comm, task_pid_nr(current), signr);
1169 #if defined(__i386__) && !defined(__arch_um__)
1170 printk("code at %08lx: ", regs->ip);
1173 for (i = 0; i < 16; i++) {
1176 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1178 printk("%02x ", insn);
1188 static int __init setup_print_fatal_signals(char *str)
1190 get_option (&str, &print_fatal_signals);
1195 __setup("print-fatal-signals=", setup_print_fatal_signals);
1198 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1200 return send_signal(sig, info, p, 1);
1204 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1206 return send_signal(sig, info, t, 0);
1209 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1212 unsigned long flags;
1215 if (lock_task_sighand(p, &flags)) {
1216 ret = send_signal(sig, info, p, group);
1217 unlock_task_sighand(p, &flags);
1224 * Force a signal that the process can't ignore: if necessary
1225 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1227 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1228 * since we do not want to have a signal handler that was blocked
1229 * be invoked when user space had explicitly blocked it.
1231 * We don't want to have recursive SIGSEGV's etc, for example,
1232 * that is why we also clear SIGNAL_UNKILLABLE.
1235 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1237 unsigned long int flags;
1238 int ret, blocked, ignored;
1239 struct k_sigaction *action;
1241 spin_lock_irqsave(&t->sighand->siglock, flags);
1242 action = &t->sighand->action[sig-1];
1243 ignored = action->sa.sa_handler == SIG_IGN;
1244 blocked = sigismember(&t->blocked, sig);
1245 if (blocked || ignored) {
1246 action->sa.sa_handler = SIG_DFL;
1248 sigdelset(&t->blocked, sig);
1249 recalc_sigpending_and_wake(t);
1252 if (action->sa.sa_handler == SIG_DFL)
1253 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1254 ret = specific_send_sig_info(sig, info, t);
1255 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1261 * Nuke all other threads in the group.
1263 int zap_other_threads(struct task_struct *p)
1265 struct task_struct *t = p;
1268 p->signal->group_stop_count = 0;
1270 while_each_thread(p, t) {
1271 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1274 /* Don't bother with already dead threads */
1277 sigaddset(&t->pending.signal, SIGKILL);
1278 signal_wake_up(t, 1);
1284 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1285 unsigned long *flags)
1287 struct sighand_struct *sighand;
1290 local_irq_save(*flags);
1292 sighand = rcu_dereference(tsk->sighand);
1293 if (unlikely(sighand == NULL)) {
1295 local_irq_restore(*flags);
1299 spin_lock(&sighand->siglock);
1300 if (likely(sighand == tsk->sighand)) {
1304 spin_unlock(&sighand->siglock);
1306 local_irq_restore(*flags);
1313 * send signal info to all the members of a group
1315 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1320 ret = check_kill_permission(sig, info, p);
1324 ret = do_send_sig_info(sig, info, p, true);
1330 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1331 * control characters do (^C, ^Z etc)
1332 * - the caller must hold at least a readlock on tasklist_lock
1334 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1336 struct task_struct *p = NULL;
1337 int retval, success;
1341 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1342 int err = group_send_sig_info(sig, info, p);
1345 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1346 return success ? 0 : retval;
1349 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1352 struct task_struct *p;
1356 p = pid_task(pid, PIDTYPE_PID);
1358 error = group_send_sig_info(sig, info, p);
1359 if (unlikely(error == -ESRCH))
1361 * The task was unhashed in between, try again.
1362 * If it is dead, pid_task() will return NULL,
1363 * if we race with de_thread() it will find the
1373 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1377 error = kill_pid_info(sig, info, find_vpid(pid));
1382 static int kill_as_cred_perm(const struct cred *cred,
1383 struct task_struct *target)
1385 const struct cred *pcred = __task_cred(target);
1386 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1387 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1392 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1393 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1394 const struct cred *cred, u32 secid)
1397 struct task_struct *p;
1398 unsigned long flags;
1400 if (!valid_signal(sig))
1404 p = pid_task(pid, PIDTYPE_PID);
1409 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1413 ret = security_task_kill(p, info, sig, secid);
1418 if (lock_task_sighand(p, &flags)) {
1419 ret = __send_signal(sig, info, p, 1, 0);
1420 unlock_task_sighand(p, &flags);
1428 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1431 * kill_something_info() interprets pid in interesting ways just like kill(2).
1433 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1434 * is probably wrong. Should make it like BSD or SYSV.
1437 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1443 ret = kill_pid_info(sig, info, find_vpid(pid));
1448 read_lock(&tasklist_lock);
1450 ret = __kill_pgrp_info(sig, info,
1451 pid ? find_vpid(-pid) : task_pgrp(current));
1453 int retval = 0, count = 0;
1454 struct task_struct * p;
1456 for_each_process(p) {
1457 if (task_pid_vnr(p) > 1 &&
1458 !same_thread_group(p, current)) {
1459 int err = group_send_sig_info(sig, info, p);
1465 ret = count ? retval : -ESRCH;
1467 read_unlock(&tasklist_lock);
1473 * These are for backward compatibility with the rest of the kernel source.
1476 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1479 * Make sure legacy kernel users don't send in bad values
1480 * (normal paths check this in check_kill_permission).
1482 if (!valid_signal(sig))
1485 return do_send_sig_info(sig, info, p, false);
1488 #define __si_special(priv) \
1489 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1492 send_sig(int sig, struct task_struct *p, int priv)
1494 return send_sig_info(sig, __si_special(priv), p);
1498 force_sig(int sig, struct task_struct *p)
1500 force_sig_info(sig, SEND_SIG_PRIV, p);
1504 * When things go south during signal handling, we
1505 * will force a SIGSEGV. And if the signal that caused
1506 * the problem was already a SIGSEGV, we'll want to
1507 * make sure we don't even try to deliver the signal..
1510 force_sigsegv(int sig, struct task_struct *p)
1512 if (sig == SIGSEGV) {
1513 unsigned long flags;
1514 spin_lock_irqsave(&p->sighand->siglock, flags);
1515 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1516 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1518 force_sig(SIGSEGV, p);
1522 int kill_pgrp(struct pid *pid, int sig, int priv)
1526 read_lock(&tasklist_lock);
1527 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1528 read_unlock(&tasklist_lock);
1532 EXPORT_SYMBOL(kill_pgrp);
1534 int kill_pid(struct pid *pid, int sig, int priv)
1536 return kill_pid_info(sig, __si_special(priv), pid);
1538 EXPORT_SYMBOL(kill_pid);
1541 * These functions support sending signals using preallocated sigqueue
1542 * structures. This is needed "because realtime applications cannot
1543 * afford to lose notifications of asynchronous events, like timer
1544 * expirations or I/O completions". In the case of POSIX Timers
1545 * we allocate the sigqueue structure from the timer_create. If this
1546 * allocation fails we are able to report the failure to the application
1547 * with an EAGAIN error.
1549 struct sigqueue *sigqueue_alloc(void)
1551 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1554 q->flags |= SIGQUEUE_PREALLOC;
1559 void sigqueue_free(struct sigqueue *q)
1561 unsigned long flags;
1562 spinlock_t *lock = ¤t->sighand->siglock;
1564 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1566 * We must hold ->siglock while testing q->list
1567 * to serialize with collect_signal() or with
1568 * __exit_signal()->flush_sigqueue().
1570 spin_lock_irqsave(lock, flags);
1571 q->flags &= ~SIGQUEUE_PREALLOC;
1573 * If it is queued it will be freed when dequeued,
1574 * like the "regular" sigqueue.
1576 if (!list_empty(&q->list))
1578 spin_unlock_irqrestore(lock, flags);
1584 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1586 int sig = q->info.si_signo;
1587 struct sigpending *pending;
1588 unsigned long flags;
1591 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1594 if (!likely(lock_task_sighand(t, &flags)))
1597 ret = 1; /* the signal is ignored */
1598 result = TRACE_SIGNAL_IGNORED;
1599 if (!prepare_signal(sig, t, false))
1603 if (unlikely(!list_empty(&q->list))) {
1605 * If an SI_TIMER entry is already queue just increment
1606 * the overrun count.
1608 BUG_ON(q->info.si_code != SI_TIMER);
1609 q->info.si_overrun++;
1610 result = TRACE_SIGNAL_ALREADY_PENDING;
1613 q->info.si_overrun = 0;
1615 signalfd_notify(t, sig);
1616 pending = group ? &t->signal->shared_pending : &t->pending;
1617 list_add_tail(&q->list, &pending->list);
1618 sigaddset(&pending->signal, sig);
1619 complete_signal(sig, t, group);
1620 result = TRACE_SIGNAL_DELIVERED;
1622 trace_signal_generate(sig, &q->info, t, group, result);
1623 unlock_task_sighand(t, &flags);
1629 * Let a parent know about the death of a child.
1630 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1632 * Returns true if our parent ignored us and so we've switched to
1635 bool do_notify_parent(struct task_struct *tsk, int sig)
1637 struct siginfo info;
1638 unsigned long flags;
1639 struct sighand_struct *psig;
1640 bool autoreap = false;
1644 /* do_notify_parent_cldstop should have been called instead. */
1645 BUG_ON(task_is_stopped_or_traced(tsk));
1647 BUG_ON(!tsk->ptrace &&
1648 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1650 if (sig != SIGCHLD) {
1652 * This is only possible if parent == real_parent.
1653 * Check if it has changed security domain.
1655 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1659 info.si_signo = sig;
1662 * We are under tasklist_lock here so our parent is tied to
1663 * us and cannot change.
1665 * task_active_pid_ns will always return the same pid namespace
1666 * until a task passes through release_task.
1668 * write_lock() currently calls preempt_disable() which is the
1669 * same as rcu_read_lock(), but according to Oleg, this is not
1670 * correct to rely on this
1673 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1674 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1678 info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
1679 info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
1681 info.si_status = tsk->exit_code & 0x7f;
1682 if (tsk->exit_code & 0x80)
1683 info.si_code = CLD_DUMPED;
1684 else if (tsk->exit_code & 0x7f)
1685 info.si_code = CLD_KILLED;
1687 info.si_code = CLD_EXITED;
1688 info.si_status = tsk->exit_code >> 8;
1691 psig = tsk->parent->sighand;
1692 spin_lock_irqsave(&psig->siglock, flags);
1693 if (!tsk->ptrace && sig == SIGCHLD &&
1694 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1695 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1697 * We are exiting and our parent doesn't care. POSIX.1
1698 * defines special semantics for setting SIGCHLD to SIG_IGN
1699 * or setting the SA_NOCLDWAIT flag: we should be reaped
1700 * automatically and not left for our parent's wait4 call.
1701 * Rather than having the parent do it as a magic kind of
1702 * signal handler, we just set this to tell do_exit that we
1703 * can be cleaned up without becoming a zombie. Note that
1704 * we still call __wake_up_parent in this case, because a
1705 * blocked sys_wait4 might now return -ECHILD.
1707 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1708 * is implementation-defined: we do (if you don't want
1709 * it, just use SIG_IGN instead).
1712 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1715 if (valid_signal(sig) && sig)
1716 __group_send_sig_info(sig, &info, tsk->parent);
1717 __wake_up_parent(tsk, tsk->parent);
1718 spin_unlock_irqrestore(&psig->siglock, flags);
1724 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1725 * @tsk: task reporting the state change
1726 * @for_ptracer: the notification is for ptracer
1727 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1729 * Notify @tsk's parent that the stopped/continued state has changed. If
1730 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1731 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1734 * Must be called with tasklist_lock at least read locked.
1736 static void do_notify_parent_cldstop(struct task_struct *tsk,
1737 bool for_ptracer, int why)
1739 struct siginfo info;
1740 unsigned long flags;
1741 struct task_struct *parent;
1742 struct sighand_struct *sighand;
1745 parent = tsk->parent;
1747 tsk = tsk->group_leader;
1748 parent = tsk->real_parent;
1751 info.si_signo = SIGCHLD;
1754 * see comment in do_notify_parent() about the following 4 lines
1757 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1758 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1761 info.si_utime = cputime_to_clock_t(tsk->utime);
1762 info.si_stime = cputime_to_clock_t(tsk->stime);
1767 info.si_status = SIGCONT;
1770 info.si_status = tsk->signal->group_exit_code & 0x7f;
1773 info.si_status = tsk->exit_code & 0x7f;
1779 sighand = parent->sighand;
1780 spin_lock_irqsave(&sighand->siglock, flags);
1781 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1782 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1783 __group_send_sig_info(SIGCHLD, &info, parent);
1785 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1787 __wake_up_parent(tsk, parent);
1788 spin_unlock_irqrestore(&sighand->siglock, flags);
1791 static inline int may_ptrace_stop(void)
1793 if (!likely(current->ptrace))
1796 * Are we in the middle of do_coredump?
1797 * If so and our tracer is also part of the coredump stopping
1798 * is a deadlock situation, and pointless because our tracer
1799 * is dead so don't allow us to stop.
1800 * If SIGKILL was already sent before the caller unlocked
1801 * ->siglock we must see ->core_state != NULL. Otherwise it
1802 * is safe to enter schedule().
1804 if (unlikely(current->mm->core_state) &&
1805 unlikely(current->mm == current->parent->mm))
1812 * Return non-zero if there is a SIGKILL that should be waking us up.
1813 * Called with the siglock held.
1815 static int sigkill_pending(struct task_struct *tsk)
1817 return sigismember(&tsk->pending.signal, SIGKILL) ||
1818 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1822 * This must be called with current->sighand->siglock held.
1824 * This should be the path for all ptrace stops.
1825 * We always set current->last_siginfo while stopped here.
1826 * That makes it a way to test a stopped process for
1827 * being ptrace-stopped vs being job-control-stopped.
1829 * If we actually decide not to stop at all because the tracer
1830 * is gone, we keep current->exit_code unless clear_code.
1832 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1833 __releases(¤t->sighand->siglock)
1834 __acquires(¤t->sighand->siglock)
1836 bool gstop_done = false;
1838 if (arch_ptrace_stop_needed(exit_code, info)) {
1840 * The arch code has something special to do before a
1841 * ptrace stop. This is allowed to block, e.g. for faults
1842 * on user stack pages. We can't keep the siglock while
1843 * calling arch_ptrace_stop, so we must release it now.
1844 * To preserve proper semantics, we must do this before
1845 * any signal bookkeeping like checking group_stop_count.
1846 * Meanwhile, a SIGKILL could come in before we retake the
1847 * siglock. That must prevent us from sleeping in TASK_TRACED.
1848 * So after regaining the lock, we must check for SIGKILL.
1850 spin_unlock_irq(¤t->sighand->siglock);
1851 arch_ptrace_stop(exit_code, info);
1852 spin_lock_irq(¤t->sighand->siglock);
1853 if (sigkill_pending(current))
1858 * We're committing to trapping. TRACED should be visible before
1859 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1860 * Also, transition to TRACED and updates to ->jobctl should be
1861 * atomic with respect to siglock and should be done after the arch
1862 * hook as siglock is released and regrabbed across it.
1864 set_current_state(TASK_TRACED);
1866 current->last_siginfo = info;
1867 current->exit_code = exit_code;
1870 * If @why is CLD_STOPPED, we're trapping to participate in a group
1871 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1872 * across siglock relocks since INTERRUPT was scheduled, PENDING
1873 * could be clear now. We act as if SIGCONT is received after
1874 * TASK_TRACED is entered - ignore it.
1876 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1877 gstop_done = task_participate_group_stop(current);
1879 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1880 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1881 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1882 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1884 /* entering a trap, clear TRAPPING */
1885 task_clear_jobctl_trapping(current);
1887 spin_unlock_irq(¤t->sighand->siglock);
1888 read_lock(&tasklist_lock);
1889 if (may_ptrace_stop()) {
1891 * Notify parents of the stop.
1893 * While ptraced, there are two parents - the ptracer and
1894 * the real_parent of the group_leader. The ptracer should
1895 * know about every stop while the real parent is only
1896 * interested in the completion of group stop. The states
1897 * for the two don't interact with each other. Notify
1898 * separately unless they're gonna be duplicates.
1900 do_notify_parent_cldstop(current, true, why);
1901 if (gstop_done && ptrace_reparented(current))
1902 do_notify_parent_cldstop(current, false, why);
1905 * Don't want to allow preemption here, because
1906 * sys_ptrace() needs this task to be inactive.
1908 * XXX: implement read_unlock_no_resched().
1911 read_unlock(&tasklist_lock);
1912 preempt_enable_no_resched();
1916 * By the time we got the lock, our tracer went away.
1917 * Don't drop the lock yet, another tracer may come.
1919 * If @gstop_done, the ptracer went away between group stop
1920 * completion and here. During detach, it would have set
1921 * JOBCTL_STOP_PENDING on us and we'll re-enter
1922 * TASK_STOPPED in do_signal_stop() on return, so notifying
1923 * the real parent of the group stop completion is enough.
1926 do_notify_parent_cldstop(current, false, why);
1928 __set_current_state(TASK_RUNNING);
1930 current->exit_code = 0;
1931 read_unlock(&tasklist_lock);
1935 * While in TASK_TRACED, we were considered "frozen enough".
1936 * Now that we woke up, it's crucial if we're supposed to be
1937 * frozen that we freeze now before running anything substantial.
1942 * We are back. Now reacquire the siglock before touching
1943 * last_siginfo, so that we are sure to have synchronized with
1944 * any signal-sending on another CPU that wants to examine it.
1946 spin_lock_irq(¤t->sighand->siglock);
1947 current->last_siginfo = NULL;
1949 /* LISTENING can be set only during STOP traps, clear it */
1950 current->jobctl &= ~JOBCTL_LISTENING;
1953 * Queued signals ignored us while we were stopped for tracing.
1954 * So check for any that we should take before resuming user mode.
1955 * This sets TIF_SIGPENDING, but never clears it.
1957 recalc_sigpending_tsk(current);
1960 static void ptrace_do_notify(int signr, int exit_code, int why)
1964 memset(&info, 0, sizeof info);
1965 info.si_signo = signr;
1966 info.si_code = exit_code;
1967 info.si_pid = task_pid_vnr(current);
1968 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1970 /* Let the debugger run. */
1971 ptrace_stop(exit_code, why, 1, &info);
1974 void ptrace_notify(int exit_code)
1976 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1977 if (unlikely(current->task_works))
1980 spin_lock_irq(¤t->sighand->siglock);
1981 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1982 spin_unlock_irq(¤t->sighand->siglock);
1986 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1987 * @signr: signr causing group stop if initiating
1989 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1990 * and participate in it. If already set, participate in the existing
1991 * group stop. If participated in a group stop (and thus slept), %true is
1992 * returned with siglock released.
1994 * If ptraced, this function doesn't handle stop itself. Instead,
1995 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1996 * untouched. The caller must ensure that INTERRUPT trap handling takes
1997 * places afterwards.
2000 * Must be called with @current->sighand->siglock held, which is released
2004 * %false if group stop is already cancelled or ptrace trap is scheduled.
2005 * %true if participated in group stop.
2007 static bool do_signal_stop(int signr)
2008 __releases(¤t->sighand->siglock)
2010 struct signal_struct *sig = current->signal;
2012 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2013 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2014 struct task_struct *t;
2016 /* signr will be recorded in task->jobctl for retries */
2017 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2019 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2020 unlikely(signal_group_exit(sig)))
2023 * There is no group stop already in progress. We must
2026 * While ptraced, a task may be resumed while group stop is
2027 * still in effect and then receive a stop signal and
2028 * initiate another group stop. This deviates from the
2029 * usual behavior as two consecutive stop signals can't
2030 * cause two group stops when !ptraced. That is why we
2031 * also check !task_is_stopped(t) below.
2033 * The condition can be distinguished by testing whether
2034 * SIGNAL_STOP_STOPPED is already set. Don't generate
2035 * group_exit_code in such case.
2037 * This is not necessary for SIGNAL_STOP_CONTINUED because
2038 * an intervening stop signal is required to cause two
2039 * continued events regardless of ptrace.
2041 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2042 sig->group_exit_code = signr;
2044 sig->group_stop_count = 0;
2046 if (task_set_jobctl_pending(current, signr | gstop))
2047 sig->group_stop_count++;
2049 for (t = next_thread(current); t != current;
2050 t = next_thread(t)) {
2052 * Setting state to TASK_STOPPED for a group
2053 * stop is always done with the siglock held,
2054 * so this check has no races.
2056 if (!task_is_stopped(t) &&
2057 task_set_jobctl_pending(t, signr | gstop)) {
2058 sig->group_stop_count++;
2059 if (likely(!(t->ptrace & PT_SEIZED)))
2060 signal_wake_up(t, 0);
2062 ptrace_trap_notify(t);
2067 if (likely(!current->ptrace)) {
2071 * If there are no other threads in the group, or if there
2072 * is a group stop in progress and we are the last to stop,
2073 * report to the parent.
2075 if (task_participate_group_stop(current))
2076 notify = CLD_STOPPED;
2078 __set_current_state(TASK_STOPPED);
2079 spin_unlock_irq(¤t->sighand->siglock);
2082 * Notify the parent of the group stop completion. Because
2083 * we're not holding either the siglock or tasklist_lock
2084 * here, ptracer may attach inbetween; however, this is for
2085 * group stop and should always be delivered to the real
2086 * parent of the group leader. The new ptracer will get
2087 * its notification when this task transitions into
2091 read_lock(&tasklist_lock);
2092 do_notify_parent_cldstop(current, false, notify);
2093 read_unlock(&tasklist_lock);
2096 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2101 * While ptraced, group stop is handled by STOP trap.
2102 * Schedule it and let the caller deal with it.
2104 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2110 * do_jobctl_trap - take care of ptrace jobctl traps
2112 * When PT_SEIZED, it's used for both group stop and explicit
2113 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2114 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2115 * the stop signal; otherwise, %SIGTRAP.
2117 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2118 * number as exit_code and no siginfo.
2121 * Must be called with @current->sighand->siglock held, which may be
2122 * released and re-acquired before returning with intervening sleep.
2124 static void do_jobctl_trap(void)
2126 struct signal_struct *signal = current->signal;
2127 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2129 if (current->ptrace & PT_SEIZED) {
2130 if (!signal->group_stop_count &&
2131 !(signal->flags & SIGNAL_STOP_STOPPED))
2133 WARN_ON_ONCE(!signr);
2134 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2137 WARN_ON_ONCE(!signr);
2138 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2139 current->exit_code = 0;
2143 static int ptrace_signal(int signr, siginfo_t *info)
2145 ptrace_signal_deliver();
2147 * We do not check sig_kernel_stop(signr) but set this marker
2148 * unconditionally because we do not know whether debugger will
2149 * change signr. This flag has no meaning unless we are going
2150 * to stop after return from ptrace_stop(). In this case it will
2151 * be checked in do_signal_stop(), we should only stop if it was
2152 * not cleared by SIGCONT while we were sleeping. See also the
2153 * comment in dequeue_signal().
2155 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2156 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2158 /* We're back. Did the debugger cancel the sig? */
2159 signr = current->exit_code;
2163 current->exit_code = 0;
2166 * Update the siginfo structure if the signal has
2167 * changed. If the debugger wanted something
2168 * specific in the siginfo structure then it should
2169 * have updated *info via PTRACE_SETSIGINFO.
2171 if (signr != info->si_signo) {
2172 info->si_signo = signr;
2174 info->si_code = SI_USER;
2176 info->si_pid = task_pid_vnr(current->parent);
2177 info->si_uid = from_kuid_munged(current_user_ns(),
2178 task_uid(current->parent));
2182 /* If the (new) signal is now blocked, requeue it. */
2183 if (sigismember(¤t->blocked, signr)) {
2184 specific_send_sig_info(signr, info, current);
2191 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2192 struct pt_regs *regs, void *cookie)
2194 struct sighand_struct *sighand = current->sighand;
2195 struct signal_struct *signal = current->signal;
2198 if (unlikely(current->task_works))
2201 if (unlikely(uprobe_deny_signal()))
2206 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2207 * While in TASK_STOPPED, we were considered "frozen enough".
2208 * Now that we woke up, it's crucial if we're supposed to be
2209 * frozen that we freeze now before running anything substantial.
2213 spin_lock_irq(&sighand->siglock);
2215 * Every stopped thread goes here after wakeup. Check to see if
2216 * we should notify the parent, prepare_signal(SIGCONT) encodes
2217 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2219 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2222 if (signal->flags & SIGNAL_CLD_CONTINUED)
2223 why = CLD_CONTINUED;
2227 signal->flags &= ~SIGNAL_CLD_MASK;
2229 spin_unlock_irq(&sighand->siglock);
2232 * Notify the parent that we're continuing. This event is
2233 * always per-process and doesn't make whole lot of sense
2234 * for ptracers, who shouldn't consume the state via
2235 * wait(2) either, but, for backward compatibility, notify
2236 * the ptracer of the group leader too unless it's gonna be
2239 read_lock(&tasklist_lock);
2240 do_notify_parent_cldstop(current, false, why);
2242 if (ptrace_reparented(current->group_leader))
2243 do_notify_parent_cldstop(current->group_leader,
2245 read_unlock(&tasklist_lock);
2251 struct k_sigaction *ka;
2253 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2257 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2259 spin_unlock_irq(&sighand->siglock);
2263 signr = dequeue_signal(current, ¤t->blocked, info);
2266 break; /* will return 0 */
2268 if (unlikely(current->ptrace) && signr != SIGKILL) {
2269 signr = ptrace_signal(signr, info);
2274 ka = &sighand->action[signr-1];
2276 /* Trace actually delivered signals. */
2277 trace_signal_deliver(signr, info, ka);
2279 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2281 if (ka->sa.sa_handler != SIG_DFL) {
2282 /* Run the handler. */
2285 if (ka->sa.sa_flags & SA_ONESHOT)
2286 ka->sa.sa_handler = SIG_DFL;
2288 break; /* will return non-zero "signr" value */
2292 * Now we are doing the default action for this signal.
2294 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2298 * Global init gets no signals it doesn't want.
2299 * Container-init gets no signals it doesn't want from same
2302 * Note that if global/container-init sees a sig_kernel_only()
2303 * signal here, the signal must have been generated internally
2304 * or must have come from an ancestor namespace. In either
2305 * case, the signal cannot be dropped.
2307 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2308 !sig_kernel_only(signr))
2311 if (sig_kernel_stop(signr)) {
2313 * The default action is to stop all threads in
2314 * the thread group. The job control signals
2315 * do nothing in an orphaned pgrp, but SIGSTOP
2316 * always works. Note that siglock needs to be
2317 * dropped during the call to is_orphaned_pgrp()
2318 * because of lock ordering with tasklist_lock.
2319 * This allows an intervening SIGCONT to be posted.
2320 * We need to check for that and bail out if necessary.
2322 if (signr != SIGSTOP) {
2323 spin_unlock_irq(&sighand->siglock);
2325 /* signals can be posted during this window */
2327 if (is_current_pgrp_orphaned())
2330 spin_lock_irq(&sighand->siglock);
2333 if (likely(do_signal_stop(info->si_signo))) {
2334 /* It released the siglock. */
2339 * We didn't actually stop, due to a race
2340 * with SIGCONT or something like that.
2345 spin_unlock_irq(&sighand->siglock);
2348 * Anything else is fatal, maybe with a core dump.
2350 current->flags |= PF_SIGNALED;
2352 if (sig_kernel_coredump(signr)) {
2353 if (print_fatal_signals)
2354 print_fatal_signal(info->si_signo);
2356 * If it was able to dump core, this kills all
2357 * other threads in the group and synchronizes with
2358 * their demise. If we lost the race with another
2359 * thread getting here, it set group_exit_code
2360 * first and our do_group_exit call below will use
2361 * that value and ignore the one we pass it.
2367 * Death signals, no core dump.
2369 do_group_exit(info->si_signo);
2372 spin_unlock_irq(&sighand->siglock);
2377 * signal_delivered -
2378 * @sig: number of signal being delivered
2379 * @info: siginfo_t of signal being delivered
2380 * @ka: sigaction setting that chose the handler
2381 * @regs: user register state
2382 * @stepping: nonzero if debugger single-step or block-step in use
2384 * This function should be called when a signal has succesfully been
2385 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2386 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2387 * is set in @ka->sa.sa_flags. Tracing is notified.
2389 void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2390 struct pt_regs *regs, int stepping)
2394 /* A signal was successfully delivered, and the
2395 saved sigmask was stored on the signal frame,
2396 and will be restored by sigreturn. So we can
2397 simply clear the restore sigmask flag. */
2398 clear_restore_sigmask();
2400 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2401 if (!(ka->sa.sa_flags & SA_NODEFER))
2402 sigaddset(&blocked, sig);
2403 set_current_blocked(&blocked);
2404 tracehook_signal_handler(sig, info, ka, regs, stepping);
2408 * It could be that complete_signal() picked us to notify about the
2409 * group-wide signal. Other threads should be notified now to take
2410 * the shared signals in @which since we will not.
2412 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2415 struct task_struct *t;
2417 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2418 if (sigisemptyset(&retarget))
2422 while_each_thread(tsk, t) {
2423 if (t->flags & PF_EXITING)
2426 if (!has_pending_signals(&retarget, &t->blocked))
2428 /* Remove the signals this thread can handle. */
2429 sigandsets(&retarget, &retarget, &t->blocked);
2431 if (!signal_pending(t))
2432 signal_wake_up(t, 0);
2434 if (sigisemptyset(&retarget))
2439 void exit_signals(struct task_struct *tsk)
2445 * @tsk is about to have PF_EXITING set - lock out users which
2446 * expect stable threadgroup.
2448 threadgroup_change_begin(tsk);
2450 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2451 tsk->flags |= PF_EXITING;
2452 threadgroup_change_end(tsk);
2456 spin_lock_irq(&tsk->sighand->siglock);
2458 * From now this task is not visible for group-wide signals,
2459 * see wants_signal(), do_signal_stop().
2461 tsk->flags |= PF_EXITING;
2463 threadgroup_change_end(tsk);
2465 if (!signal_pending(tsk))
2468 unblocked = tsk->blocked;
2469 signotset(&unblocked);
2470 retarget_shared_pending(tsk, &unblocked);
2472 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2473 task_participate_group_stop(tsk))
2474 group_stop = CLD_STOPPED;
2476 spin_unlock_irq(&tsk->sighand->siglock);
2479 * If group stop has completed, deliver the notification. This
2480 * should always go to the real parent of the group leader.
2482 if (unlikely(group_stop)) {
2483 read_lock(&tasklist_lock);
2484 do_notify_parent_cldstop(tsk, false, group_stop);
2485 read_unlock(&tasklist_lock);
2489 EXPORT_SYMBOL(recalc_sigpending);
2490 EXPORT_SYMBOL_GPL(dequeue_signal);
2491 EXPORT_SYMBOL(flush_signals);
2492 EXPORT_SYMBOL(force_sig);
2493 EXPORT_SYMBOL(send_sig);
2494 EXPORT_SYMBOL(send_sig_info);
2495 EXPORT_SYMBOL(sigprocmask);
2496 EXPORT_SYMBOL(block_all_signals);
2497 EXPORT_SYMBOL(unblock_all_signals);
2501 * System call entry points.
2505 * sys_restart_syscall - restart a system call
2507 SYSCALL_DEFINE0(restart_syscall)
2509 struct restart_block *restart = ¤t_thread_info()->restart_block;
2510 return restart->fn(restart);
2513 long do_no_restart_syscall(struct restart_block *param)
2518 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2520 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2521 sigset_t newblocked;
2522 /* A set of now blocked but previously unblocked signals. */
2523 sigandnsets(&newblocked, newset, ¤t->blocked);
2524 retarget_shared_pending(tsk, &newblocked);
2526 tsk->blocked = *newset;
2527 recalc_sigpending();
2531 * set_current_blocked - change current->blocked mask
2534 * It is wrong to change ->blocked directly, this helper should be used
2535 * to ensure the process can't miss a shared signal we are going to block.
2537 void set_current_blocked(sigset_t *newset)
2539 struct task_struct *tsk = current;
2540 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2541 spin_lock_irq(&tsk->sighand->siglock);
2542 __set_task_blocked(tsk, newset);
2543 spin_unlock_irq(&tsk->sighand->siglock);
2546 void __set_current_blocked(const sigset_t *newset)
2548 struct task_struct *tsk = current;
2550 spin_lock_irq(&tsk->sighand->siglock);
2551 __set_task_blocked(tsk, newset);
2552 spin_unlock_irq(&tsk->sighand->siglock);
2556 * This is also useful for kernel threads that want to temporarily
2557 * (or permanently) block certain signals.
2559 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2560 * interface happily blocks "unblockable" signals like SIGKILL
2563 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2565 struct task_struct *tsk = current;
2568 /* Lockless, only current can change ->blocked, never from irq */
2570 *oldset = tsk->blocked;
2574 sigorsets(&newset, &tsk->blocked, set);
2577 sigandnsets(&newset, &tsk->blocked, set);
2586 __set_current_blocked(&newset);
2591 * sys_rt_sigprocmask - change the list of currently blocked signals
2592 * @how: whether to add, remove, or set signals
2593 * @nset: stores pending signals
2594 * @oset: previous value of signal mask if non-null
2595 * @sigsetsize: size of sigset_t type
2597 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2598 sigset_t __user *, oset, size_t, sigsetsize)
2600 sigset_t old_set, new_set;
2603 /* XXX: Don't preclude handling different sized sigset_t's. */
2604 if (sigsetsize != sizeof(sigset_t))
2607 old_set = current->blocked;
2610 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2612 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2614 error = sigprocmask(how, &new_set, NULL);
2620 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2627 long do_sigpending(void __user *set, unsigned long sigsetsize)
2629 long error = -EINVAL;
2632 if (sigsetsize > sizeof(sigset_t))
2635 spin_lock_irq(¤t->sighand->siglock);
2636 sigorsets(&pending, ¤t->pending.signal,
2637 ¤t->signal->shared_pending.signal);
2638 spin_unlock_irq(¤t->sighand->siglock);
2640 /* Outside the lock because only this thread touches it. */
2641 sigandsets(&pending, ¤t->blocked, &pending);
2644 if (!copy_to_user(set, &pending, sigsetsize))
2652 * sys_rt_sigpending - examine a pending signal that has been raised
2654 * @set: stores pending signals
2655 * @sigsetsize: size of sigset_t type or larger
2657 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2659 return do_sigpending(set, sigsetsize);
2662 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2664 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2668 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2670 if (from->si_code < 0)
2671 return __copy_to_user(to, from, sizeof(siginfo_t))
2674 * If you change siginfo_t structure, please be sure
2675 * this code is fixed accordingly.
2676 * Please remember to update the signalfd_copyinfo() function
2677 * inside fs/signalfd.c too, in case siginfo_t changes.
2678 * It should never copy any pad contained in the structure
2679 * to avoid security leaks, but must copy the generic
2680 * 3 ints plus the relevant union member.
2682 err = __put_user(from->si_signo, &to->si_signo);
2683 err |= __put_user(from->si_errno, &to->si_errno);
2684 err |= __put_user((short)from->si_code, &to->si_code);
2685 switch (from->si_code & __SI_MASK) {
2687 err |= __put_user(from->si_pid, &to->si_pid);
2688 err |= __put_user(from->si_uid, &to->si_uid);
2691 err |= __put_user(from->si_tid, &to->si_tid);
2692 err |= __put_user(from->si_overrun, &to->si_overrun);
2693 err |= __put_user(from->si_ptr, &to->si_ptr);
2696 err |= __put_user(from->si_band, &to->si_band);
2697 err |= __put_user(from->si_fd, &to->si_fd);
2700 err |= __put_user(from->si_addr, &to->si_addr);
2701 #ifdef __ARCH_SI_TRAPNO
2702 err |= __put_user(from->si_trapno, &to->si_trapno);
2704 #ifdef BUS_MCEERR_AO
2706 * Other callers might not initialize the si_lsb field,
2707 * so check explicitly for the right codes here.
2709 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2710 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2714 err |= __put_user(from->si_pid, &to->si_pid);
2715 err |= __put_user(from->si_uid, &to->si_uid);
2716 err |= __put_user(from->si_status, &to->si_status);
2717 err |= __put_user(from->si_utime, &to->si_utime);
2718 err |= __put_user(from->si_stime, &to->si_stime);
2720 case __SI_RT: /* This is not generated by the kernel as of now. */
2721 case __SI_MESGQ: /* But this is */
2722 err |= __put_user(from->si_pid, &to->si_pid);
2723 err |= __put_user(from->si_uid, &to->si_uid);
2724 err |= __put_user(from->si_ptr, &to->si_ptr);
2726 #ifdef __ARCH_SIGSYS
2728 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2729 err |= __put_user(from->si_syscall, &to->si_syscall);
2730 err |= __put_user(from->si_arch, &to->si_arch);
2733 default: /* this is just in case for now ... */
2734 err |= __put_user(from->si_pid, &to->si_pid);
2735 err |= __put_user(from->si_uid, &to->si_uid);
2744 * do_sigtimedwait - wait for queued signals specified in @which
2745 * @which: queued signals to wait for
2746 * @info: if non-null, the signal's siginfo is returned here
2747 * @ts: upper bound on process time suspension
2749 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2750 const struct timespec *ts)
2752 struct task_struct *tsk = current;
2753 long timeout = MAX_SCHEDULE_TIMEOUT;
2754 sigset_t mask = *which;
2758 if (!timespec_valid(ts))
2760 timeout = timespec_to_jiffies(ts);
2762 * We can be close to the next tick, add another one
2763 * to ensure we will wait at least the time asked for.
2765 if (ts->tv_sec || ts->tv_nsec)
2770 * Invert the set of allowed signals to get those we want to block.
2772 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2775 spin_lock_irq(&tsk->sighand->siglock);
2776 sig = dequeue_signal(tsk, &mask, info);
2777 if (!sig && timeout) {
2779 * None ready, temporarily unblock those we're interested
2780 * while we are sleeping in so that we'll be awakened when
2781 * they arrive. Unblocking is always fine, we can avoid
2782 * set_current_blocked().
2784 tsk->real_blocked = tsk->blocked;
2785 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2786 recalc_sigpending();
2787 spin_unlock_irq(&tsk->sighand->siglock);
2789 timeout = schedule_timeout_interruptible(timeout);
2791 spin_lock_irq(&tsk->sighand->siglock);
2792 __set_task_blocked(tsk, &tsk->real_blocked);
2793 siginitset(&tsk->real_blocked, 0);
2794 sig = dequeue_signal(tsk, &mask, info);
2796 spin_unlock_irq(&tsk->sighand->siglock);
2800 return timeout ? -EINTR : -EAGAIN;
2804 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2806 * @uthese: queued signals to wait for
2807 * @uinfo: if non-null, the signal's siginfo is returned here
2808 * @uts: upper bound on process time suspension
2809 * @sigsetsize: size of sigset_t type
2811 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2812 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2820 /* XXX: Don't preclude handling different sized sigset_t's. */
2821 if (sigsetsize != sizeof(sigset_t))
2824 if (copy_from_user(&these, uthese, sizeof(these)))
2828 if (copy_from_user(&ts, uts, sizeof(ts)))
2832 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2834 if (ret > 0 && uinfo) {
2835 if (copy_siginfo_to_user(uinfo, &info))
2843 * sys_kill - send a signal to a process
2844 * @pid: the PID of the process
2845 * @sig: signal to be sent
2847 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2849 struct siginfo info;
2851 info.si_signo = sig;
2853 info.si_code = SI_USER;
2854 info.si_pid = task_tgid_vnr(current);
2855 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2857 return kill_something_info(sig, &info, pid);
2861 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2863 struct task_struct *p;
2867 p = find_task_by_vpid(pid);
2868 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2869 error = check_kill_permission(sig, info, p);
2871 * The null signal is a permissions and process existence
2872 * probe. No signal is actually delivered.
2874 if (!error && sig) {
2875 error = do_send_sig_info(sig, info, p, false);
2877 * If lock_task_sighand() failed we pretend the task
2878 * dies after receiving the signal. The window is tiny,
2879 * and the signal is private anyway.
2881 if (unlikely(error == -ESRCH))
2890 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2892 struct siginfo info;
2894 info.si_signo = sig;
2896 info.si_code = SI_TKILL;
2897 info.si_pid = task_tgid_vnr(current);
2898 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2900 return do_send_specific(tgid, pid, sig, &info);
2904 * sys_tgkill - send signal to one specific thread
2905 * @tgid: the thread group ID of the thread
2906 * @pid: the PID of the thread
2907 * @sig: signal to be sent
2909 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2910 * exists but it's not belonging to the target process anymore. This
2911 * method solves the problem of threads exiting and PIDs getting reused.
2913 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2915 /* This is only valid for single tasks */
2916 if (pid <= 0 || tgid <= 0)
2919 return do_tkill(tgid, pid, sig);
2923 * sys_tkill - send signal to one specific task
2924 * @pid: the PID of the task
2925 * @sig: signal to be sent
2927 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2929 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2931 /* This is only valid for single tasks */
2935 return do_tkill(0, pid, sig);
2939 * sys_rt_sigqueueinfo - send signal information to a signal
2940 * @pid: the PID of the thread
2941 * @sig: signal to be sent
2942 * @uinfo: signal info to be sent
2944 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2945 siginfo_t __user *, uinfo)
2949 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2952 /* Not even root can pretend to send signals from the kernel.
2953 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2955 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2956 /* We used to allow any < 0 si_code */
2957 WARN_ON_ONCE(info.si_code < 0);
2960 info.si_signo = sig;
2962 /* POSIX.1b doesn't mention process groups. */
2963 return kill_proc_info(sig, &info, pid);
2966 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2968 /* This is only valid for single tasks */
2969 if (pid <= 0 || tgid <= 0)
2972 /* Not even root can pretend to send signals from the kernel.
2973 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2975 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2976 /* We used to allow any < 0 si_code */
2977 WARN_ON_ONCE(info->si_code < 0);
2980 info->si_signo = sig;
2982 return do_send_specific(tgid, pid, sig, info);
2985 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2986 siginfo_t __user *, uinfo)
2990 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2993 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2996 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2998 struct task_struct *t = current;
2999 struct k_sigaction *k;
3002 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3005 k = &t->sighand->action[sig-1];
3007 spin_lock_irq(¤t->sighand->siglock);
3012 sigdelsetmask(&act->sa.sa_mask,
3013 sigmask(SIGKILL) | sigmask(SIGSTOP));
3017 * "Setting a signal action to SIG_IGN for a signal that is
3018 * pending shall cause the pending signal to be discarded,
3019 * whether or not it is blocked."
3021 * "Setting a signal action to SIG_DFL for a signal that is
3022 * pending and whose default action is to ignore the signal
3023 * (for example, SIGCHLD), shall cause the pending signal to
3024 * be discarded, whether or not it is blocked"
3026 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3028 sigaddset(&mask, sig);
3029 rm_from_queue_full(&mask, &t->signal->shared_pending);
3031 rm_from_queue_full(&mask, &t->pending);
3033 } while (t != current);
3037 spin_unlock_irq(¤t->sighand->siglock);
3042 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3047 oss.ss_sp = (void __user *) current->sas_ss_sp;
3048 oss.ss_size = current->sas_ss_size;
3049 oss.ss_flags = sas_ss_flags(sp);
3057 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3059 error = __get_user(ss_sp, &uss->ss_sp) |
3060 __get_user(ss_flags, &uss->ss_flags) |
3061 __get_user(ss_size, &uss->ss_size);
3066 if (on_sig_stack(sp))
3071 * Note - this code used to test ss_flags incorrectly:
3072 * old code may have been written using ss_flags==0
3073 * to mean ss_flags==SS_ONSTACK (as this was the only
3074 * way that worked) - this fix preserves that older
3077 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3080 if (ss_flags == SS_DISABLE) {
3085 if (ss_size < MINSIGSTKSZ)
3089 current->sas_ss_sp = (unsigned long) ss_sp;
3090 current->sas_ss_size = ss_size;
3096 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3098 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3099 __put_user(oss.ss_size, &uoss->ss_size) |
3100 __put_user(oss.ss_flags, &uoss->ss_flags);
3106 #ifdef CONFIG_GENERIC_SIGALTSTACK
3107 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3109 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3113 int restore_altstack(const stack_t __user *uss)
3115 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3116 /* squash all but EFAULT for now */
3117 return err == -EFAULT ? err : 0;
3120 int __save_altstack(stack_t __user *uss, unsigned long sp)
3122 struct task_struct *t = current;
3123 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3124 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3125 __put_user(t->sas_ss_size, &uss->ss_size);
3128 #ifdef CONFIG_COMPAT
3129 #ifdef CONFIG_GENERIC_SIGALTSTACK
3130 asmlinkage long compat_sys_sigaltstack(const compat_stack_t __user *uss_ptr,
3131 compat_stack_t __user *uoss_ptr)
3138 compat_stack_t uss32;
3140 memset(&uss, 0, sizeof(stack_t));
3141 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3143 uss.ss_sp = compat_ptr(uss32.ss_sp);
3144 uss.ss_flags = uss32.ss_flags;
3145 uss.ss_size = uss32.ss_size;
3149 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3150 (stack_t __force __user *) &uoss,
3151 compat_user_stack_pointer());
3153 if (ret >= 0 && uoss_ptr) {
3154 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3155 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3156 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3157 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3163 int compat_restore_altstack(const compat_stack_t __user *uss)
3165 int err = compat_sys_sigaltstack(uss, NULL);
3166 /* squash all but -EFAULT for now */
3167 return err == -EFAULT ? err : 0;
3170 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3172 struct task_struct *t = current;
3173 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3174 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3175 __put_user(t->sas_ss_size, &uss->ss_size);
3180 #ifdef __ARCH_WANT_SYS_SIGPENDING
3183 * sys_sigpending - examine pending signals
3184 * @set: where mask of pending signal is returned
3186 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3188 return do_sigpending(set, sizeof(*set));
3193 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3195 * sys_sigprocmask - examine and change blocked signals
3196 * @how: whether to add, remove, or set signals
3197 * @nset: signals to add or remove (if non-null)
3198 * @oset: previous value of signal mask if non-null
3200 * Some platforms have their own version with special arguments;
3201 * others support only sys_rt_sigprocmask.
3204 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3205 old_sigset_t __user *, oset)
3207 old_sigset_t old_set, new_set;
3208 sigset_t new_blocked;
3210 old_set = current->blocked.sig[0];
3213 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3215 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3217 new_blocked = current->blocked;
3221 sigaddsetmask(&new_blocked, new_set);
3224 sigdelsetmask(&new_blocked, new_set);
3227 new_blocked.sig[0] = new_set;
3233 __set_current_blocked(&new_blocked);
3237 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3243 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3245 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3247 * sys_rt_sigaction - alter an action taken by a process
3248 * @sig: signal to be sent
3249 * @act: new sigaction
3250 * @oact: used to save the previous sigaction
3251 * @sigsetsize: size of sigset_t type
3253 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3254 const struct sigaction __user *, act,
3255 struct sigaction __user *, oact,
3258 struct k_sigaction new_sa, old_sa;
3261 /* XXX: Don't preclude handling different sized sigset_t's. */
3262 if (sigsetsize != sizeof(sigset_t))
3266 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3270 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3273 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3279 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3281 #ifdef __ARCH_WANT_SYS_SGETMASK
3284 * For backwards compatibility. Functionality superseded by sigprocmask.
3286 SYSCALL_DEFINE0(sgetmask)
3289 return current->blocked.sig[0];
3292 SYSCALL_DEFINE1(ssetmask, int, newmask)
3294 int old = current->blocked.sig[0];
3297 set_current_blocked(&newset);
3301 #endif /* __ARCH_WANT_SGETMASK */
3303 #ifdef __ARCH_WANT_SYS_SIGNAL
3305 * For backwards compatibility. Functionality superseded by sigaction.
3307 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3309 struct k_sigaction new_sa, old_sa;
3312 new_sa.sa.sa_handler = handler;
3313 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3314 sigemptyset(&new_sa.sa.sa_mask);
3316 ret = do_sigaction(sig, &new_sa, &old_sa);
3318 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3320 #endif /* __ARCH_WANT_SYS_SIGNAL */
3322 #ifdef __ARCH_WANT_SYS_PAUSE
3324 SYSCALL_DEFINE0(pause)
3326 while (!signal_pending(current)) {
3327 current->state = TASK_INTERRUPTIBLE;
3330 return -ERESTARTNOHAND;
3335 int sigsuspend(sigset_t *set)
3337 current->saved_sigmask = current->blocked;
3338 set_current_blocked(set);
3340 current->state = TASK_INTERRUPTIBLE;
3342 set_restore_sigmask();
3343 return -ERESTARTNOHAND;
3346 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3348 * sys_rt_sigsuspend - replace the signal mask for a value with the
3349 * @unewset value until a signal is received
3350 * @unewset: new signal mask value
3351 * @sigsetsize: size of sigset_t type
3353 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3357 /* XXX: Don't preclude handling different sized sigset_t's. */
3358 if (sigsetsize != sizeof(sigset_t))
3361 if (copy_from_user(&newset, unewset, sizeof(newset)))
3363 return sigsuspend(&newset);
3365 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3367 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3372 void __init signals_init(void)
3374 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3377 #ifdef CONFIG_KGDB_KDB
3378 #include <linux/kdb.h>
3380 * kdb_send_sig_info - Allows kdb to send signals without exposing
3381 * signal internals. This function checks if the required locks are
3382 * available before calling the main signal code, to avoid kdb
3386 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3388 static struct task_struct *kdb_prev_t;
3390 if (!spin_trylock(&t->sighand->siglock)) {
3391 kdb_printf("Can't do kill command now.\n"
3392 "The sigmask lock is held somewhere else in "
3393 "kernel, try again later\n");
3396 spin_unlock(&t->sighand->siglock);
3397 new_t = kdb_prev_t != t;
3399 if (t->state != TASK_RUNNING && new_t) {
3400 kdb_printf("Process is not RUNNING, sending a signal from "
3401 "kdb risks deadlock\n"
3402 "on the run queue locks. "
3403 "The signal has _not_ been sent.\n"
3404 "Reissue the kill command if you want to risk "
3408 sig = info->si_signo;
3409 if (send_sig_info(sig, info, t))
3410 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3413 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3415 #endif /* CONFIG_KGDB_KDB */