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_state(struct task_struct *t, unsigned int state)
685 set_tsk_thread_flag(t, TIF_SIGPENDING);
687 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
688 * case. We don't check t->state here because there is a race with it
689 * executing another processor and just now entering stopped state.
690 * By using wake_up_state, we ensure the process will wake up and
691 * handle its death signal.
693 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
698 * Remove signals in mask from the pending set and queue.
699 * Returns 1 if any signals were found.
701 * All callers must be holding the siglock.
703 * This version takes a sigset mask and looks at all signals,
704 * not just those in the first mask word.
706 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
708 struct sigqueue *q, *n;
711 sigandsets(&m, mask, &s->signal);
712 if (sigisemptyset(&m))
715 sigandnsets(&s->signal, &s->signal, mask);
716 list_for_each_entry_safe(q, n, &s->list, list) {
717 if (sigismember(mask, q->info.si_signo)) {
718 list_del_init(&q->list);
725 * Remove signals in mask from the pending set and queue.
726 * Returns 1 if any signals were found.
728 * All callers must be holding the siglock.
730 static int rm_from_queue(unsigned long mask, struct sigpending *s)
732 struct sigqueue *q, *n;
734 if (!sigtestsetmask(&s->signal, mask))
737 sigdelsetmask(&s->signal, mask);
738 list_for_each_entry_safe(q, n, &s->list, list) {
739 if (q->info.si_signo < SIGRTMIN &&
740 (mask & sigmask(q->info.si_signo))) {
741 list_del_init(&q->list);
748 static inline int is_si_special(const struct siginfo *info)
750 return info <= SEND_SIG_FORCED;
753 static inline bool si_fromuser(const struct siginfo *info)
755 return info == SEND_SIG_NOINFO ||
756 (!is_si_special(info) && SI_FROMUSER(info));
760 * called with RCU read lock from check_kill_permission()
762 static int kill_ok_by_cred(struct task_struct *t)
764 const struct cred *cred = current_cred();
765 const struct cred *tcred = __task_cred(t);
767 if (uid_eq(cred->euid, tcred->suid) ||
768 uid_eq(cred->euid, tcred->uid) ||
769 uid_eq(cred->uid, tcred->suid) ||
770 uid_eq(cred->uid, tcred->uid))
773 if (ns_capable(tcred->user_ns, CAP_KILL))
780 * Bad permissions for sending the signal
781 * - the caller must hold the RCU read lock
783 static int check_kill_permission(int sig, struct siginfo *info,
784 struct task_struct *t)
789 if (!valid_signal(sig))
792 if (!si_fromuser(info))
795 error = audit_signal_info(sig, t); /* Let audit system see the signal */
799 if (!same_thread_group(current, t) &&
800 !kill_ok_by_cred(t)) {
803 sid = task_session(t);
805 * We don't return the error if sid == NULL. The
806 * task was unhashed, the caller must notice this.
808 if (!sid || sid == task_session(current))
815 return security_task_kill(t, info, sig, 0);
819 * ptrace_trap_notify - schedule trap to notify ptracer
820 * @t: tracee wanting to notify tracer
822 * This function schedules sticky ptrace trap which is cleared on the next
823 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
826 * If @t is running, STOP trap will be taken. If trapped for STOP and
827 * ptracer is listening for events, tracee is woken up so that it can
828 * re-trap for the new event. If trapped otherwise, STOP trap will be
829 * eventually taken without returning to userland after the existing traps
830 * are finished by PTRACE_CONT.
833 * Must be called with @task->sighand->siglock held.
835 static void ptrace_trap_notify(struct task_struct *t)
837 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
838 assert_spin_locked(&t->sighand->siglock);
840 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
841 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
845 * Handle magic process-wide effects of stop/continue signals. Unlike
846 * the signal actions, these happen immediately at signal-generation
847 * time regardless of blocking, ignoring, or handling. This does the
848 * actual continuing for SIGCONT, but not the actual stopping for stop
849 * signals. The process stop is done as a signal action for SIG_DFL.
851 * Returns true if the signal should be actually delivered, otherwise
852 * it should be dropped.
854 static int prepare_signal(int sig, struct task_struct *p, bool force)
856 struct signal_struct *signal = p->signal;
857 struct task_struct *t;
859 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
861 * The process is in the middle of dying, nothing to do.
863 } else if (sig_kernel_stop(sig)) {
865 * This is a stop signal. Remove SIGCONT from all queues.
867 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
870 rm_from_queue(sigmask(SIGCONT), &t->pending);
871 } while_each_thread(p, t);
872 } else if (sig == SIGCONT) {
875 * Remove all stop signals from all queues, wake all threads.
877 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
880 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
881 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
882 if (likely(!(t->ptrace & PT_SEIZED)))
883 wake_up_state(t, __TASK_STOPPED);
885 ptrace_trap_notify(t);
886 } while_each_thread(p, t);
889 * Notify the parent with CLD_CONTINUED if we were stopped.
891 * If we were in the middle of a group stop, we pretend it
892 * was already finished, and then continued. Since SIGCHLD
893 * doesn't queue we report only CLD_STOPPED, as if the next
894 * CLD_CONTINUED was dropped.
897 if (signal->flags & SIGNAL_STOP_STOPPED)
898 why |= SIGNAL_CLD_CONTINUED;
899 else if (signal->group_stop_count)
900 why |= SIGNAL_CLD_STOPPED;
904 * The first thread which returns from do_signal_stop()
905 * will take ->siglock, notice SIGNAL_CLD_MASK, and
906 * notify its parent. See get_signal_to_deliver().
908 signal->flags = why | SIGNAL_STOP_CONTINUED;
909 signal->group_stop_count = 0;
910 signal->group_exit_code = 0;
914 return !sig_ignored(p, sig, force);
918 * Test if P wants to take SIG. After we've checked all threads with this,
919 * it's equivalent to finding no threads not blocking SIG. Any threads not
920 * blocking SIG were ruled out because they are not running and already
921 * have pending signals. Such threads will dequeue from the shared queue
922 * as soon as they're available, so putting the signal on the shared queue
923 * will be equivalent to sending it to one such thread.
925 static inline int wants_signal(int sig, struct task_struct *p)
927 if (sigismember(&p->blocked, sig))
929 if (p->flags & PF_EXITING)
933 if (task_is_stopped_or_traced(p))
935 return task_curr(p) || !signal_pending(p);
938 static void complete_signal(int sig, struct task_struct *p, int group)
940 struct signal_struct *signal = p->signal;
941 struct task_struct *t;
944 * Now find a thread we can wake up to take the signal off the queue.
946 * If the main thread wants the signal, it gets first crack.
947 * Probably the least surprising to the average bear.
949 if (wants_signal(sig, p))
951 else if (!group || thread_group_empty(p))
953 * There is just one thread and it does not need to be woken.
954 * It will dequeue unblocked signals before it runs again.
959 * Otherwise try to find a suitable thread.
961 t = signal->curr_target;
962 while (!wants_signal(sig, t)) {
964 if (t == signal->curr_target)
966 * No thread needs to be woken.
967 * Any eligible threads will see
968 * the signal in the queue soon.
972 signal->curr_target = t;
976 * Found a killable thread. If the signal will be fatal,
977 * then start taking the whole group down immediately.
979 if (sig_fatal(p, sig) &&
980 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
981 !sigismember(&t->real_blocked, sig) &&
982 (sig == SIGKILL || !t->ptrace)) {
984 * This signal will be fatal to the whole group.
986 if (!sig_kernel_coredump(sig)) {
988 * Start a group exit and wake everybody up.
989 * This way we don't have other threads
990 * running and doing things after a slower
991 * thread has the fatal signal pending.
993 signal->flags = SIGNAL_GROUP_EXIT;
994 signal->group_exit_code = sig;
995 signal->group_stop_count = 0;
998 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
999 sigaddset(&t->pending.signal, SIGKILL);
1000 signal_wake_up(t, 1);
1001 } while_each_thread(p, t);
1007 * The signal is already in the shared-pending queue.
1008 * Tell the chosen thread to wake up and dequeue it.
1010 signal_wake_up(t, sig == SIGKILL);
1014 static inline int legacy_queue(struct sigpending *signals, int sig)
1016 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1019 #ifdef CONFIG_USER_NS
1020 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1022 if (current_user_ns() == task_cred_xxx(t, user_ns))
1025 if (SI_FROMKERNEL(info))
1029 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1030 make_kuid(current_user_ns(), info->si_uid));
1034 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1040 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1041 int group, int from_ancestor_ns)
1043 struct sigpending *pending;
1045 int override_rlimit;
1046 int ret = 0, result;
1048 assert_spin_locked(&t->sighand->siglock);
1050 result = TRACE_SIGNAL_IGNORED;
1051 if (!prepare_signal(sig, t,
1052 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1055 pending = group ? &t->signal->shared_pending : &t->pending;
1057 * Short-circuit ignored signals and support queuing
1058 * exactly one non-rt signal, so that we can get more
1059 * detailed information about the cause of the signal.
1061 result = TRACE_SIGNAL_ALREADY_PENDING;
1062 if (legacy_queue(pending, sig))
1065 result = TRACE_SIGNAL_DELIVERED;
1067 * fast-pathed signals for kernel-internal things like SIGSTOP
1070 if (info == SEND_SIG_FORCED)
1074 * Real-time signals must be queued if sent by sigqueue, or
1075 * some other real-time mechanism. It is implementation
1076 * defined whether kill() does so. We attempt to do so, on
1077 * the principle of least surprise, but since kill is not
1078 * allowed to fail with EAGAIN when low on memory we just
1079 * make sure at least one signal gets delivered and don't
1080 * pass on the info struct.
1083 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1085 override_rlimit = 0;
1087 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1090 list_add_tail(&q->list, &pending->list);
1091 switch ((unsigned long) info) {
1092 case (unsigned long) SEND_SIG_NOINFO:
1093 q->info.si_signo = sig;
1094 q->info.si_errno = 0;
1095 q->info.si_code = SI_USER;
1096 q->info.si_pid = task_tgid_nr_ns(current,
1097 task_active_pid_ns(t));
1098 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1100 case (unsigned long) SEND_SIG_PRIV:
1101 q->info.si_signo = sig;
1102 q->info.si_errno = 0;
1103 q->info.si_code = SI_KERNEL;
1108 copy_siginfo(&q->info, info);
1109 if (from_ancestor_ns)
1114 userns_fixup_signal_uid(&q->info, t);
1116 } else if (!is_si_special(info)) {
1117 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1119 * Queue overflow, abort. We may abort if the
1120 * signal was rt and sent by user using something
1121 * other than kill().
1123 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1128 * This is a silent loss of information. We still
1129 * send the signal, but the *info bits are lost.
1131 result = TRACE_SIGNAL_LOSE_INFO;
1136 signalfd_notify(t, sig);
1137 sigaddset(&pending->signal, sig);
1138 complete_signal(sig, t, group);
1140 trace_signal_generate(sig, info, t, group, result);
1144 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1147 int from_ancestor_ns = 0;
1149 #ifdef CONFIG_PID_NS
1150 from_ancestor_ns = si_fromuser(info) &&
1151 !task_pid_nr_ns(current, task_active_pid_ns(t));
1154 return __send_signal(sig, info, t, group, from_ancestor_ns);
1157 static void print_fatal_signal(int signr)
1159 struct pt_regs *regs = signal_pt_regs();
1160 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1161 current->comm, task_pid_nr(current), signr);
1163 #if defined(__i386__) && !defined(__arch_um__)
1164 printk("code at %08lx: ", regs->ip);
1167 for (i = 0; i < 16; i++) {
1170 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1172 printk("%02x ", insn);
1182 static int __init setup_print_fatal_signals(char *str)
1184 get_option (&str, &print_fatal_signals);
1189 __setup("print-fatal-signals=", setup_print_fatal_signals);
1192 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1194 return send_signal(sig, info, p, 1);
1198 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1200 return send_signal(sig, info, t, 0);
1203 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1206 unsigned long flags;
1209 if (lock_task_sighand(p, &flags)) {
1210 ret = send_signal(sig, info, p, group);
1211 unlock_task_sighand(p, &flags);
1218 * Force a signal that the process can't ignore: if necessary
1219 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1221 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1222 * since we do not want to have a signal handler that was blocked
1223 * be invoked when user space had explicitly blocked it.
1225 * We don't want to have recursive SIGSEGV's etc, for example,
1226 * that is why we also clear SIGNAL_UNKILLABLE.
1229 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1231 unsigned long int flags;
1232 int ret, blocked, ignored;
1233 struct k_sigaction *action;
1235 spin_lock_irqsave(&t->sighand->siglock, flags);
1236 action = &t->sighand->action[sig-1];
1237 ignored = action->sa.sa_handler == SIG_IGN;
1238 blocked = sigismember(&t->blocked, sig);
1239 if (blocked || ignored) {
1240 action->sa.sa_handler = SIG_DFL;
1242 sigdelset(&t->blocked, sig);
1243 recalc_sigpending_and_wake(t);
1246 if (action->sa.sa_handler == SIG_DFL)
1247 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1248 ret = specific_send_sig_info(sig, info, t);
1249 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1255 * Nuke all other threads in the group.
1257 int zap_other_threads(struct task_struct *p)
1259 struct task_struct *t = p;
1262 p->signal->group_stop_count = 0;
1264 while_each_thread(p, t) {
1265 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1268 /* Don't bother with already dead threads */
1271 sigaddset(&t->pending.signal, SIGKILL);
1272 signal_wake_up(t, 1);
1278 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1279 unsigned long *flags)
1281 struct sighand_struct *sighand;
1284 local_irq_save(*flags);
1286 sighand = rcu_dereference(tsk->sighand);
1287 if (unlikely(sighand == NULL)) {
1289 local_irq_restore(*flags);
1293 spin_lock(&sighand->siglock);
1294 if (likely(sighand == tsk->sighand)) {
1298 spin_unlock(&sighand->siglock);
1300 local_irq_restore(*flags);
1307 * send signal info to all the members of a group
1309 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1314 ret = check_kill_permission(sig, info, p);
1318 ret = do_send_sig_info(sig, info, p, true);
1324 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1325 * control characters do (^C, ^Z etc)
1326 * - the caller must hold at least a readlock on tasklist_lock
1328 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1330 struct task_struct *p = NULL;
1331 int retval, success;
1335 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1336 int err = group_send_sig_info(sig, info, p);
1339 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1340 return success ? 0 : retval;
1343 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1346 struct task_struct *p;
1350 p = pid_task(pid, PIDTYPE_PID);
1352 error = group_send_sig_info(sig, info, p);
1353 if (unlikely(error == -ESRCH))
1355 * The task was unhashed in between, try again.
1356 * If it is dead, pid_task() will return NULL,
1357 * if we race with de_thread() it will find the
1367 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1371 error = kill_pid_info(sig, info, find_vpid(pid));
1376 static int kill_as_cred_perm(const struct cred *cred,
1377 struct task_struct *target)
1379 const struct cred *pcred = __task_cred(target);
1380 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1381 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1386 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1387 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1388 const struct cred *cred, u32 secid)
1391 struct task_struct *p;
1392 unsigned long flags;
1394 if (!valid_signal(sig))
1398 p = pid_task(pid, PIDTYPE_PID);
1403 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1407 ret = security_task_kill(p, info, sig, secid);
1412 if (lock_task_sighand(p, &flags)) {
1413 ret = __send_signal(sig, info, p, 1, 0);
1414 unlock_task_sighand(p, &flags);
1422 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1425 * kill_something_info() interprets pid in interesting ways just like kill(2).
1427 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1428 * is probably wrong. Should make it like BSD or SYSV.
1431 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1437 ret = kill_pid_info(sig, info, find_vpid(pid));
1442 read_lock(&tasklist_lock);
1444 ret = __kill_pgrp_info(sig, info,
1445 pid ? find_vpid(-pid) : task_pgrp(current));
1447 int retval = 0, count = 0;
1448 struct task_struct * p;
1450 for_each_process(p) {
1451 if (task_pid_vnr(p) > 1 &&
1452 !same_thread_group(p, current)) {
1453 int err = group_send_sig_info(sig, info, p);
1459 ret = count ? retval : -ESRCH;
1461 read_unlock(&tasklist_lock);
1467 * These are for backward compatibility with the rest of the kernel source.
1470 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1473 * Make sure legacy kernel users don't send in bad values
1474 * (normal paths check this in check_kill_permission).
1476 if (!valid_signal(sig))
1479 return do_send_sig_info(sig, info, p, false);
1482 #define __si_special(priv) \
1483 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1486 send_sig(int sig, struct task_struct *p, int priv)
1488 return send_sig_info(sig, __si_special(priv), p);
1492 force_sig(int sig, struct task_struct *p)
1494 force_sig_info(sig, SEND_SIG_PRIV, p);
1498 * When things go south during signal handling, we
1499 * will force a SIGSEGV. And if the signal that caused
1500 * the problem was already a SIGSEGV, we'll want to
1501 * make sure we don't even try to deliver the signal..
1504 force_sigsegv(int sig, struct task_struct *p)
1506 if (sig == SIGSEGV) {
1507 unsigned long flags;
1508 spin_lock_irqsave(&p->sighand->siglock, flags);
1509 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1510 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1512 force_sig(SIGSEGV, p);
1516 int kill_pgrp(struct pid *pid, int sig, int priv)
1520 read_lock(&tasklist_lock);
1521 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1522 read_unlock(&tasklist_lock);
1526 EXPORT_SYMBOL(kill_pgrp);
1528 int kill_pid(struct pid *pid, int sig, int priv)
1530 return kill_pid_info(sig, __si_special(priv), pid);
1532 EXPORT_SYMBOL(kill_pid);
1535 * These functions support sending signals using preallocated sigqueue
1536 * structures. This is needed "because realtime applications cannot
1537 * afford to lose notifications of asynchronous events, like timer
1538 * expirations or I/O completions". In the case of POSIX Timers
1539 * we allocate the sigqueue structure from the timer_create. If this
1540 * allocation fails we are able to report the failure to the application
1541 * with an EAGAIN error.
1543 struct sigqueue *sigqueue_alloc(void)
1545 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1548 q->flags |= SIGQUEUE_PREALLOC;
1553 void sigqueue_free(struct sigqueue *q)
1555 unsigned long flags;
1556 spinlock_t *lock = ¤t->sighand->siglock;
1558 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1560 * We must hold ->siglock while testing q->list
1561 * to serialize with collect_signal() or with
1562 * __exit_signal()->flush_sigqueue().
1564 spin_lock_irqsave(lock, flags);
1565 q->flags &= ~SIGQUEUE_PREALLOC;
1567 * If it is queued it will be freed when dequeued,
1568 * like the "regular" sigqueue.
1570 if (!list_empty(&q->list))
1572 spin_unlock_irqrestore(lock, flags);
1578 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1580 int sig = q->info.si_signo;
1581 struct sigpending *pending;
1582 unsigned long flags;
1585 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1588 if (!likely(lock_task_sighand(t, &flags)))
1591 ret = 1; /* the signal is ignored */
1592 result = TRACE_SIGNAL_IGNORED;
1593 if (!prepare_signal(sig, t, false))
1597 if (unlikely(!list_empty(&q->list))) {
1599 * If an SI_TIMER entry is already queue just increment
1600 * the overrun count.
1602 BUG_ON(q->info.si_code != SI_TIMER);
1603 q->info.si_overrun++;
1604 result = TRACE_SIGNAL_ALREADY_PENDING;
1607 q->info.si_overrun = 0;
1609 signalfd_notify(t, sig);
1610 pending = group ? &t->signal->shared_pending : &t->pending;
1611 list_add_tail(&q->list, &pending->list);
1612 sigaddset(&pending->signal, sig);
1613 complete_signal(sig, t, group);
1614 result = TRACE_SIGNAL_DELIVERED;
1616 trace_signal_generate(sig, &q->info, t, group, result);
1617 unlock_task_sighand(t, &flags);
1623 * Let a parent know about the death of a child.
1624 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1626 * Returns true if our parent ignored us and so we've switched to
1629 bool do_notify_parent(struct task_struct *tsk, int sig)
1631 struct siginfo info;
1632 unsigned long flags;
1633 struct sighand_struct *psig;
1634 bool autoreap = false;
1638 /* do_notify_parent_cldstop should have been called instead. */
1639 BUG_ON(task_is_stopped_or_traced(tsk));
1641 BUG_ON(!tsk->ptrace &&
1642 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1644 if (sig != SIGCHLD) {
1646 * This is only possible if parent == real_parent.
1647 * Check if it has changed security domain.
1649 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1653 info.si_signo = sig;
1656 * We are under tasklist_lock here so our parent is tied to
1657 * us and cannot change.
1659 * task_active_pid_ns will always return the same pid namespace
1660 * until a task passes through release_task.
1662 * write_lock() currently calls preempt_disable() which is the
1663 * same as rcu_read_lock(), but according to Oleg, this is not
1664 * correct to rely on this
1667 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1668 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1672 info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
1673 info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
1675 info.si_status = tsk->exit_code & 0x7f;
1676 if (tsk->exit_code & 0x80)
1677 info.si_code = CLD_DUMPED;
1678 else if (tsk->exit_code & 0x7f)
1679 info.si_code = CLD_KILLED;
1681 info.si_code = CLD_EXITED;
1682 info.si_status = tsk->exit_code >> 8;
1685 psig = tsk->parent->sighand;
1686 spin_lock_irqsave(&psig->siglock, flags);
1687 if (!tsk->ptrace && sig == SIGCHLD &&
1688 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1689 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1691 * We are exiting and our parent doesn't care. POSIX.1
1692 * defines special semantics for setting SIGCHLD to SIG_IGN
1693 * or setting the SA_NOCLDWAIT flag: we should be reaped
1694 * automatically and not left for our parent's wait4 call.
1695 * Rather than having the parent do it as a magic kind of
1696 * signal handler, we just set this to tell do_exit that we
1697 * can be cleaned up without becoming a zombie. Note that
1698 * we still call __wake_up_parent in this case, because a
1699 * blocked sys_wait4 might now return -ECHILD.
1701 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1702 * is implementation-defined: we do (if you don't want
1703 * it, just use SIG_IGN instead).
1706 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1709 if (valid_signal(sig) && sig)
1710 __group_send_sig_info(sig, &info, tsk->parent);
1711 __wake_up_parent(tsk, tsk->parent);
1712 spin_unlock_irqrestore(&psig->siglock, flags);
1718 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1719 * @tsk: task reporting the state change
1720 * @for_ptracer: the notification is for ptracer
1721 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1723 * Notify @tsk's parent that the stopped/continued state has changed. If
1724 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1725 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1728 * Must be called with tasklist_lock at least read locked.
1730 static void do_notify_parent_cldstop(struct task_struct *tsk,
1731 bool for_ptracer, int why)
1733 struct siginfo info;
1734 unsigned long flags;
1735 struct task_struct *parent;
1736 struct sighand_struct *sighand;
1739 parent = tsk->parent;
1741 tsk = tsk->group_leader;
1742 parent = tsk->real_parent;
1745 info.si_signo = SIGCHLD;
1748 * see comment in do_notify_parent() about the following 4 lines
1751 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1752 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1755 info.si_utime = cputime_to_clock_t(tsk->utime);
1756 info.si_stime = cputime_to_clock_t(tsk->stime);
1761 info.si_status = SIGCONT;
1764 info.si_status = tsk->signal->group_exit_code & 0x7f;
1767 info.si_status = tsk->exit_code & 0x7f;
1773 sighand = parent->sighand;
1774 spin_lock_irqsave(&sighand->siglock, flags);
1775 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1776 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1777 __group_send_sig_info(SIGCHLD, &info, parent);
1779 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1781 __wake_up_parent(tsk, parent);
1782 spin_unlock_irqrestore(&sighand->siglock, flags);
1785 static inline int may_ptrace_stop(void)
1787 if (!likely(current->ptrace))
1790 * Are we in the middle of do_coredump?
1791 * If so and our tracer is also part of the coredump stopping
1792 * is a deadlock situation, and pointless because our tracer
1793 * is dead so don't allow us to stop.
1794 * If SIGKILL was already sent before the caller unlocked
1795 * ->siglock we must see ->core_state != NULL. Otherwise it
1796 * is safe to enter schedule().
1798 * This is almost outdated, a task with the pending SIGKILL can't
1799 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1800 * after SIGKILL was already dequeued.
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();
1911 freezable_schedule();
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 /* tasklist protects us from ptrace_freeze_traced() */
1927 __set_current_state(TASK_RUNNING);
1929 current->exit_code = 0;
1930 read_unlock(&tasklist_lock);
1934 * We are back. Now reacquire the siglock before touching
1935 * last_siginfo, so that we are sure to have synchronized with
1936 * any signal-sending on another CPU that wants to examine it.
1938 spin_lock_irq(¤t->sighand->siglock);
1939 current->last_siginfo = NULL;
1941 /* LISTENING can be set only during STOP traps, clear it */
1942 current->jobctl &= ~JOBCTL_LISTENING;
1945 * Queued signals ignored us while we were stopped for tracing.
1946 * So check for any that we should take before resuming user mode.
1947 * This sets TIF_SIGPENDING, but never clears it.
1949 recalc_sigpending_tsk(current);
1952 static void ptrace_do_notify(int signr, int exit_code, int why)
1956 memset(&info, 0, sizeof info);
1957 info.si_signo = signr;
1958 info.si_code = exit_code;
1959 info.si_pid = task_pid_vnr(current);
1960 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1962 /* Let the debugger run. */
1963 ptrace_stop(exit_code, why, 1, &info);
1966 void ptrace_notify(int exit_code)
1968 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1969 if (unlikely(current->task_works))
1972 spin_lock_irq(¤t->sighand->siglock);
1973 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1974 spin_unlock_irq(¤t->sighand->siglock);
1978 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1979 * @signr: signr causing group stop if initiating
1981 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1982 * and participate in it. If already set, participate in the existing
1983 * group stop. If participated in a group stop (and thus slept), %true is
1984 * returned with siglock released.
1986 * If ptraced, this function doesn't handle stop itself. Instead,
1987 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1988 * untouched. The caller must ensure that INTERRUPT trap handling takes
1989 * places afterwards.
1992 * Must be called with @current->sighand->siglock held, which is released
1996 * %false if group stop is already cancelled or ptrace trap is scheduled.
1997 * %true if participated in group stop.
1999 static bool do_signal_stop(int signr)
2000 __releases(¤t->sighand->siglock)
2002 struct signal_struct *sig = current->signal;
2004 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2005 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2006 struct task_struct *t;
2008 /* signr will be recorded in task->jobctl for retries */
2009 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2011 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2012 unlikely(signal_group_exit(sig)))
2015 * There is no group stop already in progress. We must
2018 * While ptraced, a task may be resumed while group stop is
2019 * still in effect and then receive a stop signal and
2020 * initiate another group stop. This deviates from the
2021 * usual behavior as two consecutive stop signals can't
2022 * cause two group stops when !ptraced. That is why we
2023 * also check !task_is_stopped(t) below.
2025 * The condition can be distinguished by testing whether
2026 * SIGNAL_STOP_STOPPED is already set. Don't generate
2027 * group_exit_code in such case.
2029 * This is not necessary for SIGNAL_STOP_CONTINUED because
2030 * an intervening stop signal is required to cause two
2031 * continued events regardless of ptrace.
2033 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2034 sig->group_exit_code = signr;
2036 sig->group_stop_count = 0;
2038 if (task_set_jobctl_pending(current, signr | gstop))
2039 sig->group_stop_count++;
2041 for (t = next_thread(current); t != current;
2042 t = next_thread(t)) {
2044 * Setting state to TASK_STOPPED for a group
2045 * stop is always done with the siglock held,
2046 * so this check has no races.
2048 if (!task_is_stopped(t) &&
2049 task_set_jobctl_pending(t, signr | gstop)) {
2050 sig->group_stop_count++;
2051 if (likely(!(t->ptrace & PT_SEIZED)))
2052 signal_wake_up(t, 0);
2054 ptrace_trap_notify(t);
2059 if (likely(!current->ptrace)) {
2063 * If there are no other threads in the group, or if there
2064 * is a group stop in progress and we are the last to stop,
2065 * report to the parent.
2067 if (task_participate_group_stop(current))
2068 notify = CLD_STOPPED;
2070 __set_current_state(TASK_STOPPED);
2071 spin_unlock_irq(¤t->sighand->siglock);
2074 * Notify the parent of the group stop completion. Because
2075 * we're not holding either the siglock or tasklist_lock
2076 * here, ptracer may attach inbetween; however, this is for
2077 * group stop and should always be delivered to the real
2078 * parent of the group leader. The new ptracer will get
2079 * its notification when this task transitions into
2083 read_lock(&tasklist_lock);
2084 do_notify_parent_cldstop(current, false, notify);
2085 read_unlock(&tasklist_lock);
2088 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2089 freezable_schedule();
2093 * While ptraced, group stop is handled by STOP trap.
2094 * Schedule it and let the caller deal with it.
2096 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2102 * do_jobctl_trap - take care of ptrace jobctl traps
2104 * When PT_SEIZED, it's used for both group stop and explicit
2105 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2106 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2107 * the stop signal; otherwise, %SIGTRAP.
2109 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2110 * number as exit_code and no siginfo.
2113 * Must be called with @current->sighand->siglock held, which may be
2114 * released and re-acquired before returning with intervening sleep.
2116 static void do_jobctl_trap(void)
2118 struct signal_struct *signal = current->signal;
2119 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2121 if (current->ptrace & PT_SEIZED) {
2122 if (!signal->group_stop_count &&
2123 !(signal->flags & SIGNAL_STOP_STOPPED))
2125 WARN_ON_ONCE(!signr);
2126 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2129 WARN_ON_ONCE(!signr);
2130 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2131 current->exit_code = 0;
2135 static int ptrace_signal(int signr, siginfo_t *info)
2137 ptrace_signal_deliver();
2139 * We do not check sig_kernel_stop(signr) but set this marker
2140 * unconditionally because we do not know whether debugger will
2141 * change signr. This flag has no meaning unless we are going
2142 * to stop after return from ptrace_stop(). In this case it will
2143 * be checked in do_signal_stop(), we should only stop if it was
2144 * not cleared by SIGCONT while we were sleeping. See also the
2145 * comment in dequeue_signal().
2147 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2148 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2150 /* We're back. Did the debugger cancel the sig? */
2151 signr = current->exit_code;
2155 current->exit_code = 0;
2158 * Update the siginfo structure if the signal has
2159 * changed. If the debugger wanted something
2160 * specific in the siginfo structure then it should
2161 * have updated *info via PTRACE_SETSIGINFO.
2163 if (signr != info->si_signo) {
2164 info->si_signo = signr;
2166 info->si_code = SI_USER;
2168 info->si_pid = task_pid_vnr(current->parent);
2169 info->si_uid = from_kuid_munged(current_user_ns(),
2170 task_uid(current->parent));
2174 /* If the (new) signal is now blocked, requeue it. */
2175 if (sigismember(¤t->blocked, signr)) {
2176 specific_send_sig_info(signr, info, current);
2183 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2184 struct pt_regs *regs, void *cookie)
2186 struct sighand_struct *sighand = current->sighand;
2187 struct signal_struct *signal = current->signal;
2190 if (unlikely(current->task_works))
2193 if (unlikely(uprobe_deny_signal()))
2197 * Do this once, we can't return to user-mode if freezing() == T.
2198 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2199 * thus do not need another check after return.
2204 spin_lock_irq(&sighand->siglock);
2206 * Every stopped thread goes here after wakeup. Check to see if
2207 * we should notify the parent, prepare_signal(SIGCONT) encodes
2208 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2210 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2213 if (signal->flags & SIGNAL_CLD_CONTINUED)
2214 why = CLD_CONTINUED;
2218 signal->flags &= ~SIGNAL_CLD_MASK;
2220 spin_unlock_irq(&sighand->siglock);
2223 * Notify the parent that we're continuing. This event is
2224 * always per-process and doesn't make whole lot of sense
2225 * for ptracers, who shouldn't consume the state via
2226 * wait(2) either, but, for backward compatibility, notify
2227 * the ptracer of the group leader too unless it's gonna be
2230 read_lock(&tasklist_lock);
2231 do_notify_parent_cldstop(current, false, why);
2233 if (ptrace_reparented(current->group_leader))
2234 do_notify_parent_cldstop(current->group_leader,
2236 read_unlock(&tasklist_lock);
2242 struct k_sigaction *ka;
2244 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2248 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2250 spin_unlock_irq(&sighand->siglock);
2254 signr = dequeue_signal(current, ¤t->blocked, info);
2257 break; /* will return 0 */
2259 if (unlikely(current->ptrace) && signr != SIGKILL) {
2260 signr = ptrace_signal(signr, info);
2265 ka = &sighand->action[signr-1];
2267 /* Trace actually delivered signals. */
2268 trace_signal_deliver(signr, info, ka);
2270 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2272 if (ka->sa.sa_handler != SIG_DFL) {
2273 /* Run the handler. */
2276 if (ka->sa.sa_flags & SA_ONESHOT)
2277 ka->sa.sa_handler = SIG_DFL;
2279 break; /* will return non-zero "signr" value */
2283 * Now we are doing the default action for this signal.
2285 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2289 * Global init gets no signals it doesn't want.
2290 * Container-init gets no signals it doesn't want from same
2293 * Note that if global/container-init sees a sig_kernel_only()
2294 * signal here, the signal must have been generated internally
2295 * or must have come from an ancestor namespace. In either
2296 * case, the signal cannot be dropped.
2298 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2299 !sig_kernel_only(signr))
2302 if (sig_kernel_stop(signr)) {
2304 * The default action is to stop all threads in
2305 * the thread group. The job control signals
2306 * do nothing in an orphaned pgrp, but SIGSTOP
2307 * always works. Note that siglock needs to be
2308 * dropped during the call to is_orphaned_pgrp()
2309 * because of lock ordering with tasklist_lock.
2310 * This allows an intervening SIGCONT to be posted.
2311 * We need to check for that and bail out if necessary.
2313 if (signr != SIGSTOP) {
2314 spin_unlock_irq(&sighand->siglock);
2316 /* signals can be posted during this window */
2318 if (is_current_pgrp_orphaned())
2321 spin_lock_irq(&sighand->siglock);
2324 if (likely(do_signal_stop(info->si_signo))) {
2325 /* It released the siglock. */
2330 * We didn't actually stop, due to a race
2331 * with SIGCONT or something like that.
2336 spin_unlock_irq(&sighand->siglock);
2339 * Anything else is fatal, maybe with a core dump.
2341 current->flags |= PF_SIGNALED;
2343 if (sig_kernel_coredump(signr)) {
2344 if (print_fatal_signals)
2345 print_fatal_signal(info->si_signo);
2347 * If it was able to dump core, this kills all
2348 * other threads in the group and synchronizes with
2349 * their demise. If we lost the race with another
2350 * thread getting here, it set group_exit_code
2351 * first and our do_group_exit call below will use
2352 * that value and ignore the one we pass it.
2358 * Death signals, no core dump.
2360 do_group_exit(info->si_signo);
2363 spin_unlock_irq(&sighand->siglock);
2368 * signal_delivered -
2369 * @sig: number of signal being delivered
2370 * @info: siginfo_t of signal being delivered
2371 * @ka: sigaction setting that chose the handler
2372 * @regs: user register state
2373 * @stepping: nonzero if debugger single-step or block-step in use
2375 * This function should be called when a signal has succesfully been
2376 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2377 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2378 * is set in @ka->sa.sa_flags. Tracing is notified.
2380 void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2381 struct pt_regs *regs, int stepping)
2385 /* A signal was successfully delivered, and the
2386 saved sigmask was stored on the signal frame,
2387 and will be restored by sigreturn. So we can
2388 simply clear the restore sigmask flag. */
2389 clear_restore_sigmask();
2391 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2392 if (!(ka->sa.sa_flags & SA_NODEFER))
2393 sigaddset(&blocked, sig);
2394 set_current_blocked(&blocked);
2395 tracehook_signal_handler(sig, info, ka, regs, stepping);
2399 * It could be that complete_signal() picked us to notify about the
2400 * group-wide signal. Other threads should be notified now to take
2401 * the shared signals in @which since we will not.
2403 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2406 struct task_struct *t;
2408 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2409 if (sigisemptyset(&retarget))
2413 while_each_thread(tsk, t) {
2414 if (t->flags & PF_EXITING)
2417 if (!has_pending_signals(&retarget, &t->blocked))
2419 /* Remove the signals this thread can handle. */
2420 sigandsets(&retarget, &retarget, &t->blocked);
2422 if (!signal_pending(t))
2423 signal_wake_up(t, 0);
2425 if (sigisemptyset(&retarget))
2430 void exit_signals(struct task_struct *tsk)
2436 * @tsk is about to have PF_EXITING set - lock out users which
2437 * expect stable threadgroup.
2439 threadgroup_change_begin(tsk);
2441 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2442 tsk->flags |= PF_EXITING;
2443 threadgroup_change_end(tsk);
2447 spin_lock_irq(&tsk->sighand->siglock);
2449 * From now this task is not visible for group-wide signals,
2450 * see wants_signal(), do_signal_stop().
2452 tsk->flags |= PF_EXITING;
2454 threadgroup_change_end(tsk);
2456 if (!signal_pending(tsk))
2459 unblocked = tsk->blocked;
2460 signotset(&unblocked);
2461 retarget_shared_pending(tsk, &unblocked);
2463 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2464 task_participate_group_stop(tsk))
2465 group_stop = CLD_STOPPED;
2467 spin_unlock_irq(&tsk->sighand->siglock);
2470 * If group stop has completed, deliver the notification. This
2471 * should always go to the real parent of the group leader.
2473 if (unlikely(group_stop)) {
2474 read_lock(&tasklist_lock);
2475 do_notify_parent_cldstop(tsk, false, group_stop);
2476 read_unlock(&tasklist_lock);
2480 EXPORT_SYMBOL(recalc_sigpending);
2481 EXPORT_SYMBOL_GPL(dequeue_signal);
2482 EXPORT_SYMBOL(flush_signals);
2483 EXPORT_SYMBOL(force_sig);
2484 EXPORT_SYMBOL(send_sig);
2485 EXPORT_SYMBOL(send_sig_info);
2486 EXPORT_SYMBOL(sigprocmask);
2487 EXPORT_SYMBOL(block_all_signals);
2488 EXPORT_SYMBOL(unblock_all_signals);
2492 * System call entry points.
2496 * sys_restart_syscall - restart a system call
2498 SYSCALL_DEFINE0(restart_syscall)
2500 struct restart_block *restart = ¤t_thread_info()->restart_block;
2501 return restart->fn(restart);
2504 long do_no_restart_syscall(struct restart_block *param)
2509 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2511 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2512 sigset_t newblocked;
2513 /* A set of now blocked but previously unblocked signals. */
2514 sigandnsets(&newblocked, newset, ¤t->blocked);
2515 retarget_shared_pending(tsk, &newblocked);
2517 tsk->blocked = *newset;
2518 recalc_sigpending();
2522 * set_current_blocked - change current->blocked mask
2525 * It is wrong to change ->blocked directly, this helper should be used
2526 * to ensure the process can't miss a shared signal we are going to block.
2528 void set_current_blocked(sigset_t *newset)
2530 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2531 __set_current_blocked(newset);
2534 void __set_current_blocked(const sigset_t *newset)
2536 struct task_struct *tsk = current;
2538 spin_lock_irq(&tsk->sighand->siglock);
2539 __set_task_blocked(tsk, newset);
2540 spin_unlock_irq(&tsk->sighand->siglock);
2544 * This is also useful for kernel threads that want to temporarily
2545 * (or permanently) block certain signals.
2547 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2548 * interface happily blocks "unblockable" signals like SIGKILL
2551 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2553 struct task_struct *tsk = current;
2556 /* Lockless, only current can change ->blocked, never from irq */
2558 *oldset = tsk->blocked;
2562 sigorsets(&newset, &tsk->blocked, set);
2565 sigandnsets(&newset, &tsk->blocked, set);
2574 __set_current_blocked(&newset);
2579 * sys_rt_sigprocmask - change the list of currently blocked signals
2580 * @how: whether to add, remove, or set signals
2581 * @nset: stores pending signals
2582 * @oset: previous value of signal mask if non-null
2583 * @sigsetsize: size of sigset_t type
2585 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2586 sigset_t __user *, oset, size_t, sigsetsize)
2588 sigset_t old_set, new_set;
2591 /* XXX: Don't preclude handling different sized sigset_t's. */
2592 if (sigsetsize != sizeof(sigset_t))
2595 old_set = current->blocked;
2598 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2600 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2602 error = sigprocmask(how, &new_set, NULL);
2608 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2615 long do_sigpending(void __user *set, unsigned long sigsetsize)
2617 long error = -EINVAL;
2620 if (sigsetsize > sizeof(sigset_t))
2623 spin_lock_irq(¤t->sighand->siglock);
2624 sigorsets(&pending, ¤t->pending.signal,
2625 ¤t->signal->shared_pending.signal);
2626 spin_unlock_irq(¤t->sighand->siglock);
2628 /* Outside the lock because only this thread touches it. */
2629 sigandsets(&pending, ¤t->blocked, &pending);
2632 if (!copy_to_user(set, &pending, sigsetsize))
2640 * sys_rt_sigpending - examine a pending signal that has been raised
2642 * @set: stores pending signals
2643 * @sigsetsize: size of sigset_t type or larger
2645 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2647 return do_sigpending(set, sigsetsize);
2650 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2652 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2656 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2658 if (from->si_code < 0)
2659 return __copy_to_user(to, from, sizeof(siginfo_t))
2662 * If you change siginfo_t structure, please be sure
2663 * this code is fixed accordingly.
2664 * Please remember to update the signalfd_copyinfo() function
2665 * inside fs/signalfd.c too, in case siginfo_t changes.
2666 * It should never copy any pad contained in the structure
2667 * to avoid security leaks, but must copy the generic
2668 * 3 ints plus the relevant union member.
2670 err = __put_user(from->si_signo, &to->si_signo);
2671 err |= __put_user(from->si_errno, &to->si_errno);
2672 err |= __put_user((short)from->si_code, &to->si_code);
2673 switch (from->si_code & __SI_MASK) {
2675 err |= __put_user(from->si_pid, &to->si_pid);
2676 err |= __put_user(from->si_uid, &to->si_uid);
2679 err |= __put_user(from->si_tid, &to->si_tid);
2680 err |= __put_user(from->si_overrun, &to->si_overrun);
2681 err |= __put_user(from->si_ptr, &to->si_ptr);
2684 err |= __put_user(from->si_band, &to->si_band);
2685 err |= __put_user(from->si_fd, &to->si_fd);
2688 err |= __put_user(from->si_addr, &to->si_addr);
2689 #ifdef __ARCH_SI_TRAPNO
2690 err |= __put_user(from->si_trapno, &to->si_trapno);
2692 #ifdef BUS_MCEERR_AO
2694 * Other callers might not initialize the si_lsb field,
2695 * so check explicitly for the right codes here.
2697 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2698 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2702 err |= __put_user(from->si_pid, &to->si_pid);
2703 err |= __put_user(from->si_uid, &to->si_uid);
2704 err |= __put_user(from->si_status, &to->si_status);
2705 err |= __put_user(from->si_utime, &to->si_utime);
2706 err |= __put_user(from->si_stime, &to->si_stime);
2708 case __SI_RT: /* This is not generated by the kernel as of now. */
2709 case __SI_MESGQ: /* But this is */
2710 err |= __put_user(from->si_pid, &to->si_pid);
2711 err |= __put_user(from->si_uid, &to->si_uid);
2712 err |= __put_user(from->si_ptr, &to->si_ptr);
2714 #ifdef __ARCH_SIGSYS
2716 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2717 err |= __put_user(from->si_syscall, &to->si_syscall);
2718 err |= __put_user(from->si_arch, &to->si_arch);
2721 default: /* this is just in case for now ... */
2722 err |= __put_user(from->si_pid, &to->si_pid);
2723 err |= __put_user(from->si_uid, &to->si_uid);
2732 * do_sigtimedwait - wait for queued signals specified in @which
2733 * @which: queued signals to wait for
2734 * @info: if non-null, the signal's siginfo is returned here
2735 * @ts: upper bound on process time suspension
2737 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2738 const struct timespec *ts)
2740 struct task_struct *tsk = current;
2741 long timeout = MAX_SCHEDULE_TIMEOUT;
2742 sigset_t mask = *which;
2746 if (!timespec_valid(ts))
2748 timeout = timespec_to_jiffies(ts);
2750 * We can be close to the next tick, add another one
2751 * to ensure we will wait at least the time asked for.
2753 if (ts->tv_sec || ts->tv_nsec)
2758 * Invert the set of allowed signals to get those we want to block.
2760 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2763 spin_lock_irq(&tsk->sighand->siglock);
2764 sig = dequeue_signal(tsk, &mask, info);
2765 if (!sig && timeout) {
2767 * None ready, temporarily unblock those we're interested
2768 * while we are sleeping in so that we'll be awakened when
2769 * they arrive. Unblocking is always fine, we can avoid
2770 * set_current_blocked().
2772 tsk->real_blocked = tsk->blocked;
2773 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2774 recalc_sigpending();
2775 spin_unlock_irq(&tsk->sighand->siglock);
2777 timeout = schedule_timeout_interruptible(timeout);
2779 spin_lock_irq(&tsk->sighand->siglock);
2780 __set_task_blocked(tsk, &tsk->real_blocked);
2781 siginitset(&tsk->real_blocked, 0);
2782 sig = dequeue_signal(tsk, &mask, info);
2784 spin_unlock_irq(&tsk->sighand->siglock);
2788 return timeout ? -EINTR : -EAGAIN;
2792 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2794 * @uthese: queued signals to wait for
2795 * @uinfo: if non-null, the signal's siginfo is returned here
2796 * @uts: upper bound on process time suspension
2797 * @sigsetsize: size of sigset_t type
2799 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2800 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2808 /* XXX: Don't preclude handling different sized sigset_t's. */
2809 if (sigsetsize != sizeof(sigset_t))
2812 if (copy_from_user(&these, uthese, sizeof(these)))
2816 if (copy_from_user(&ts, uts, sizeof(ts)))
2820 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2822 if (ret > 0 && uinfo) {
2823 if (copy_siginfo_to_user(uinfo, &info))
2831 * sys_kill - send a signal to a process
2832 * @pid: the PID of the process
2833 * @sig: signal to be sent
2835 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2837 struct siginfo info;
2839 info.si_signo = sig;
2841 info.si_code = SI_USER;
2842 info.si_pid = task_tgid_vnr(current);
2843 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2845 return kill_something_info(sig, &info, pid);
2849 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2851 struct task_struct *p;
2855 p = find_task_by_vpid(pid);
2856 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2857 error = check_kill_permission(sig, info, p);
2859 * The null signal is a permissions and process existence
2860 * probe. No signal is actually delivered.
2862 if (!error && sig) {
2863 error = do_send_sig_info(sig, info, p, false);
2865 * If lock_task_sighand() failed we pretend the task
2866 * dies after receiving the signal. The window is tiny,
2867 * and the signal is private anyway.
2869 if (unlikely(error == -ESRCH))
2878 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2880 struct siginfo info;
2882 info.si_signo = sig;
2884 info.si_code = SI_TKILL;
2885 info.si_pid = task_tgid_vnr(current);
2886 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2888 return do_send_specific(tgid, pid, sig, &info);
2892 * sys_tgkill - send signal to one specific thread
2893 * @tgid: the thread group ID of the thread
2894 * @pid: the PID of the thread
2895 * @sig: signal to be sent
2897 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2898 * exists but it's not belonging to the target process anymore. This
2899 * method solves the problem of threads exiting and PIDs getting reused.
2901 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2903 /* This is only valid for single tasks */
2904 if (pid <= 0 || tgid <= 0)
2907 return do_tkill(tgid, pid, sig);
2911 * sys_tkill - send signal to one specific task
2912 * @pid: the PID of the task
2913 * @sig: signal to be sent
2915 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2917 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2919 /* This is only valid for single tasks */
2923 return do_tkill(0, pid, sig);
2927 * sys_rt_sigqueueinfo - send signal information to a signal
2928 * @pid: the PID of the thread
2929 * @sig: signal to be sent
2930 * @uinfo: signal info to be sent
2932 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2933 siginfo_t __user *, uinfo)
2937 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2940 /* Not even root can pretend to send signals from the kernel.
2941 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2943 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2944 /* We used to allow any < 0 si_code */
2945 WARN_ON_ONCE(info.si_code < 0);
2948 info.si_signo = sig;
2950 /* POSIX.1b doesn't mention process groups. */
2951 return kill_proc_info(sig, &info, pid);
2954 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2956 /* This is only valid for single tasks */
2957 if (pid <= 0 || tgid <= 0)
2960 /* Not even root can pretend to send signals from the kernel.
2961 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2963 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2964 /* We used to allow any < 0 si_code */
2965 WARN_ON_ONCE(info->si_code < 0);
2968 info->si_signo = sig;
2970 return do_send_specific(tgid, pid, sig, info);
2973 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2974 siginfo_t __user *, uinfo)
2978 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2981 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2984 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2986 struct task_struct *t = current;
2987 struct k_sigaction *k;
2990 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2993 k = &t->sighand->action[sig-1];
2995 spin_lock_irq(¤t->sighand->siglock);
3000 sigdelsetmask(&act->sa.sa_mask,
3001 sigmask(SIGKILL) | sigmask(SIGSTOP));
3005 * "Setting a signal action to SIG_IGN for a signal that is
3006 * pending shall cause the pending signal to be discarded,
3007 * whether or not it is blocked."
3009 * "Setting a signal action to SIG_DFL for a signal that is
3010 * pending and whose default action is to ignore the signal
3011 * (for example, SIGCHLD), shall cause the pending signal to
3012 * be discarded, whether or not it is blocked"
3014 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3016 sigaddset(&mask, sig);
3017 rm_from_queue_full(&mask, &t->signal->shared_pending);
3019 rm_from_queue_full(&mask, &t->pending);
3021 } while (t != current);
3025 spin_unlock_irq(¤t->sighand->siglock);
3030 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3035 oss.ss_sp = (void __user *) current->sas_ss_sp;
3036 oss.ss_size = current->sas_ss_size;
3037 oss.ss_flags = sas_ss_flags(sp);
3045 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3047 error = __get_user(ss_sp, &uss->ss_sp) |
3048 __get_user(ss_flags, &uss->ss_flags) |
3049 __get_user(ss_size, &uss->ss_size);
3054 if (on_sig_stack(sp))
3059 * Note - this code used to test ss_flags incorrectly:
3060 * old code may have been written using ss_flags==0
3061 * to mean ss_flags==SS_ONSTACK (as this was the only
3062 * way that worked) - this fix preserves that older
3065 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3068 if (ss_flags == SS_DISABLE) {
3073 if (ss_size < MINSIGSTKSZ)
3077 current->sas_ss_sp = (unsigned long) ss_sp;
3078 current->sas_ss_size = ss_size;
3084 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3086 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3087 __put_user(oss.ss_size, &uoss->ss_size) |
3088 __put_user(oss.ss_flags, &uoss->ss_flags);
3094 #ifdef CONFIG_GENERIC_SIGALTSTACK
3095 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3097 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3101 int restore_altstack(const stack_t __user *uss)
3103 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3104 /* squash all but EFAULT for now */
3105 return err == -EFAULT ? err : 0;
3108 int __save_altstack(stack_t __user *uss, unsigned long sp)
3110 struct task_struct *t = current;
3111 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3112 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3113 __put_user(t->sas_ss_size, &uss->ss_size);
3116 #ifdef CONFIG_COMPAT
3117 #ifdef CONFIG_GENERIC_SIGALTSTACK
3118 COMPAT_SYSCALL_DEFINE2(sigaltstack,
3119 const compat_stack_t __user *, uss_ptr,
3120 compat_stack_t __user *, uoss_ptr)
3127 compat_stack_t uss32;
3129 memset(&uss, 0, sizeof(stack_t));
3130 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3132 uss.ss_sp = compat_ptr(uss32.ss_sp);
3133 uss.ss_flags = uss32.ss_flags;
3134 uss.ss_size = uss32.ss_size;
3138 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3139 (stack_t __force __user *) &uoss,
3140 compat_user_stack_pointer());
3142 if (ret >= 0 && uoss_ptr) {
3143 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3144 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3145 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3146 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3152 int compat_restore_altstack(const compat_stack_t __user *uss)
3154 int err = compat_sys_sigaltstack(uss, NULL);
3155 /* squash all but -EFAULT for now */
3156 return err == -EFAULT ? err : 0;
3159 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3161 struct task_struct *t = current;
3162 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3163 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3164 __put_user(t->sas_ss_size, &uss->ss_size);
3169 #ifdef __ARCH_WANT_SYS_SIGPENDING
3172 * sys_sigpending - examine pending signals
3173 * @set: where mask of pending signal is returned
3175 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3177 return do_sigpending(set, sizeof(*set));
3182 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3184 * sys_sigprocmask - examine and change blocked signals
3185 * @how: whether to add, remove, or set signals
3186 * @nset: signals to add or remove (if non-null)
3187 * @oset: previous value of signal mask if non-null
3189 * Some platforms have their own version with special arguments;
3190 * others support only sys_rt_sigprocmask.
3193 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3194 old_sigset_t __user *, oset)
3196 old_sigset_t old_set, new_set;
3197 sigset_t new_blocked;
3199 old_set = current->blocked.sig[0];
3202 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3205 new_blocked = current->blocked;
3209 sigaddsetmask(&new_blocked, new_set);
3212 sigdelsetmask(&new_blocked, new_set);
3215 new_blocked.sig[0] = new_set;
3221 set_current_blocked(&new_blocked);
3225 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3231 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3233 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3235 * sys_rt_sigaction - alter an action taken by a process
3236 * @sig: signal to be sent
3237 * @act: new sigaction
3238 * @oact: used to save the previous sigaction
3239 * @sigsetsize: size of sigset_t type
3241 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3242 const struct sigaction __user *, act,
3243 struct sigaction __user *, oact,
3246 struct k_sigaction new_sa, old_sa;
3249 /* XXX: Don't preclude handling different sized sigset_t's. */
3250 if (sigsetsize != sizeof(sigset_t))
3254 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3258 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3261 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3267 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3269 #ifdef __ARCH_WANT_SYS_SGETMASK
3272 * For backwards compatibility. Functionality superseded by sigprocmask.
3274 SYSCALL_DEFINE0(sgetmask)
3277 return current->blocked.sig[0];
3280 SYSCALL_DEFINE1(ssetmask, int, newmask)
3282 int old = current->blocked.sig[0];
3285 siginitset(&newset, newmask);
3286 set_current_blocked(&newset);
3290 #endif /* __ARCH_WANT_SGETMASK */
3292 #ifdef __ARCH_WANT_SYS_SIGNAL
3294 * For backwards compatibility. Functionality superseded by sigaction.
3296 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3298 struct k_sigaction new_sa, old_sa;
3301 new_sa.sa.sa_handler = handler;
3302 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3303 sigemptyset(&new_sa.sa.sa_mask);
3305 ret = do_sigaction(sig, &new_sa, &old_sa);
3307 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3309 #endif /* __ARCH_WANT_SYS_SIGNAL */
3311 #ifdef __ARCH_WANT_SYS_PAUSE
3313 SYSCALL_DEFINE0(pause)
3315 while (!signal_pending(current)) {
3316 current->state = TASK_INTERRUPTIBLE;
3319 return -ERESTARTNOHAND;
3324 int sigsuspend(sigset_t *set)
3326 current->saved_sigmask = current->blocked;
3327 set_current_blocked(set);
3329 current->state = TASK_INTERRUPTIBLE;
3331 set_restore_sigmask();
3332 return -ERESTARTNOHAND;
3335 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3337 * sys_rt_sigsuspend - replace the signal mask for a value with the
3338 * @unewset value until a signal is received
3339 * @unewset: new signal mask value
3340 * @sigsetsize: size of sigset_t type
3342 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3346 /* XXX: Don't preclude handling different sized sigset_t's. */
3347 if (sigsetsize != sizeof(sigset_t))
3350 if (copy_from_user(&newset, unewset, sizeof(newset)))
3352 return sigsuspend(&newset);
3354 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3356 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3361 void __init signals_init(void)
3363 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3366 #ifdef CONFIG_KGDB_KDB
3367 #include <linux/kdb.h>
3369 * kdb_send_sig_info - Allows kdb to send signals without exposing
3370 * signal internals. This function checks if the required locks are
3371 * available before calling the main signal code, to avoid kdb
3375 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3377 static struct task_struct *kdb_prev_t;
3379 if (!spin_trylock(&t->sighand->siglock)) {
3380 kdb_printf("Can't do kill command now.\n"
3381 "The sigmask lock is held somewhere else in "
3382 "kernel, try again later\n");
3385 spin_unlock(&t->sighand->siglock);
3386 new_t = kdb_prev_t != t;
3388 if (t->state != TASK_RUNNING && new_t) {
3389 kdb_printf("Process is not RUNNING, sending a signal from "
3390 "kdb risks deadlock\n"
3391 "on the run queue locks. "
3392 "The signal has _not_ been sent.\n"
3393 "Reissue the kill command if you want to risk "
3397 sig = info->si_signo;
3398 if (send_sig_info(sig, info, t))
3399 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3402 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3404 #endif /* CONFIG_KGDB_KDB */