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/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/ratelimit.h>
26 #include <linux/tracehook.h>
27 #include <linux/capability.h>
28 #include <linux/freezer.h>
29 #include <linux/pid_namespace.h>
30 #include <linux/nsproxy.h>
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/signal.h>
34 #include <asm/param.h>
35 #include <asm/uaccess.h>
36 #include <asm/unistd.h>
37 #include <asm/siginfo.h>
38 #include "audit.h" /* audit_signal_info() */
41 * SLAB caches for signal bits.
44 static struct kmem_cache *sigqueue_cachep;
46 int print_fatal_signals __read_mostly;
48 static void __user *sig_handler(struct task_struct *t, int sig)
50 return t->sighand->action[sig - 1].sa.sa_handler;
53 static int sig_handler_ignored(void __user *handler, int sig)
55 /* Is it explicitly or implicitly ignored? */
56 return handler == SIG_IGN ||
57 (handler == SIG_DFL && sig_kernel_ignore(sig));
60 static int sig_task_ignored(struct task_struct *t, int sig,
65 handler = sig_handler(t, sig);
67 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
68 handler == SIG_DFL && !from_ancestor_ns)
71 return sig_handler_ignored(handler, sig);
74 static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
77 * Blocked signals are never ignored, since the
78 * signal handler may change by the time it is
81 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
84 if (!sig_task_ignored(t, sig, from_ancestor_ns))
88 * Tracers may want to know about even ignored signals.
94 * Re-calculate pending state from the set of locally pending
95 * signals, globally pending signals, and blocked signals.
97 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
102 switch (_NSIG_WORDS) {
104 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
105 ready |= signal->sig[i] &~ blocked->sig[i];
108 case 4: ready = signal->sig[3] &~ blocked->sig[3];
109 ready |= signal->sig[2] &~ blocked->sig[2];
110 ready |= signal->sig[1] &~ blocked->sig[1];
111 ready |= signal->sig[0] &~ blocked->sig[0];
114 case 2: ready = signal->sig[1] &~ blocked->sig[1];
115 ready |= signal->sig[0] &~ blocked->sig[0];
118 case 1: ready = signal->sig[0] &~ blocked->sig[0];
123 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
125 static int recalc_sigpending_tsk(struct task_struct *t)
127 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
128 PENDING(&t->pending, &t->blocked) ||
129 PENDING(&t->signal->shared_pending, &t->blocked)) {
130 set_tsk_thread_flag(t, TIF_SIGPENDING);
134 * We must never clear the flag in another thread, or in current
135 * when it's possible the current syscall is returning -ERESTART*.
136 * So we don't clear it here, and only callers who know they should do.
142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
143 * This is superfluous when called on current, the wakeup is a harmless no-op.
145 void recalc_sigpending_and_wake(struct task_struct *t)
147 if (recalc_sigpending_tsk(t))
148 signal_wake_up(t, 0);
151 void recalc_sigpending(void)
153 if (!recalc_sigpending_tsk(current) && !freezing(current))
154 clear_thread_flag(TIF_SIGPENDING);
158 /* Given the mask, find the first available signal that should be serviced. */
160 #define SYNCHRONOUS_MASK \
161 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
162 sigmask(SIGTRAP) | sigmask(SIGFPE))
164 int next_signal(struct sigpending *pending, sigset_t *mask)
166 unsigned long i, *s, *m, x;
169 s = pending->signal.sig;
173 * Handle the first word specially: it contains the
174 * synchronous signals that need to be dequeued first.
178 if (x & SYNCHRONOUS_MASK)
179 x &= SYNCHRONOUS_MASK;
184 switch (_NSIG_WORDS) {
186 for (i = 1; i < _NSIG_WORDS; ++i) {
190 sig = ffz(~x) + i*_NSIG_BPW + 1;
199 sig = ffz(~x) + _NSIG_BPW + 1;
210 static inline void print_dropped_signal(int sig)
212 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
214 if (!print_fatal_signals)
217 if (!__ratelimit(&ratelimit_state))
220 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
221 current->comm, current->pid, sig);
225 * task_set_jobctl_pending - set jobctl pending bits
227 * @mask: pending bits to set
229 * Clear @mask from @task->jobctl. @mask must be subset of
230 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
231 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
232 * cleared. If @task is already being killed or exiting, this function
236 * Must be called with @task->sighand->siglock held.
239 * %true if @mask is set, %false if made noop because @task was dying.
241 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
243 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
244 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
245 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
247 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
250 if (mask & JOBCTL_STOP_SIGMASK)
251 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
253 task->jobctl |= mask;
258 * task_clear_jobctl_trapping - clear jobctl trapping bit
261 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
262 * Clear it and wake up the ptracer. Note that we don't need any further
263 * locking. @task->siglock guarantees that @task->parent points to the
267 * Must be called with @task->sighand->siglock held.
269 void task_clear_jobctl_trapping(struct task_struct *task)
271 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
272 task->jobctl &= ~JOBCTL_TRAPPING;
273 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
278 * task_clear_jobctl_pending - clear jobctl pending bits
280 * @mask: pending bits to clear
282 * Clear @mask from @task->jobctl. @mask must be subset of
283 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
284 * STOP bits are cleared together.
286 * If clearing of @mask leaves no stop or trap pending, this function calls
287 * task_clear_jobctl_trapping().
290 * Must be called with @task->sighand->siglock held.
292 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
294 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
296 if (mask & JOBCTL_STOP_PENDING)
297 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
299 task->jobctl &= ~mask;
301 if (!(task->jobctl & JOBCTL_PENDING_MASK))
302 task_clear_jobctl_trapping(task);
306 * task_participate_group_stop - participate in a group stop
307 * @task: task participating in a group stop
309 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
310 * Group stop states are cleared and the group stop count is consumed if
311 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
312 * stop, the appropriate %SIGNAL_* flags are set.
315 * Must be called with @task->sighand->siglock held.
318 * %true if group stop completion should be notified to the parent, %false
321 static bool task_participate_group_stop(struct task_struct *task)
323 struct signal_struct *sig = task->signal;
324 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
326 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
328 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
333 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
334 sig->group_stop_count--;
337 * Tell the caller to notify completion iff we are entering into a
338 * fresh group stop. Read comment in do_signal_stop() for details.
340 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
341 sig->flags = SIGNAL_STOP_STOPPED;
348 * allocate a new signal queue record
349 * - this may be called without locks if and only if t == current, otherwise an
350 * appropriate lock must be held to stop the target task from exiting
352 static struct sigqueue *
353 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
355 struct sigqueue *q = NULL;
356 struct user_struct *user;
359 * Protect access to @t credentials. This can go away when all
360 * callers hold rcu read lock.
363 user = get_uid(__task_cred(t)->user);
364 atomic_inc(&user->sigpending);
367 if (override_rlimit ||
368 atomic_read(&user->sigpending) <=
369 task_rlimit(t, RLIMIT_SIGPENDING)) {
370 q = kmem_cache_alloc(sigqueue_cachep, flags);
372 print_dropped_signal(sig);
375 if (unlikely(q == NULL)) {
376 atomic_dec(&user->sigpending);
379 INIT_LIST_HEAD(&q->list);
387 static void __sigqueue_free(struct sigqueue *q)
389 if (q->flags & SIGQUEUE_PREALLOC)
391 atomic_dec(&q->user->sigpending);
393 kmem_cache_free(sigqueue_cachep, q);
396 void flush_sigqueue(struct sigpending *queue)
400 sigemptyset(&queue->signal);
401 while (!list_empty(&queue->list)) {
402 q = list_entry(queue->list.next, struct sigqueue , list);
403 list_del_init(&q->list);
409 * Flush all pending signals for a task.
411 void __flush_signals(struct task_struct *t)
413 clear_tsk_thread_flag(t, TIF_SIGPENDING);
414 flush_sigqueue(&t->pending);
415 flush_sigqueue(&t->signal->shared_pending);
418 void flush_signals(struct task_struct *t)
422 spin_lock_irqsave(&t->sighand->siglock, flags);
424 spin_unlock_irqrestore(&t->sighand->siglock, flags);
427 static void __flush_itimer_signals(struct sigpending *pending)
429 sigset_t signal, retain;
430 struct sigqueue *q, *n;
432 signal = pending->signal;
433 sigemptyset(&retain);
435 list_for_each_entry_safe(q, n, &pending->list, list) {
436 int sig = q->info.si_signo;
438 if (likely(q->info.si_code != SI_TIMER)) {
439 sigaddset(&retain, sig);
441 sigdelset(&signal, sig);
442 list_del_init(&q->list);
447 sigorsets(&pending->signal, &signal, &retain);
450 void flush_itimer_signals(void)
452 struct task_struct *tsk = current;
455 spin_lock_irqsave(&tsk->sighand->siglock, flags);
456 __flush_itimer_signals(&tsk->pending);
457 __flush_itimer_signals(&tsk->signal->shared_pending);
458 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
461 void ignore_signals(struct task_struct *t)
465 for (i = 0; i < _NSIG; ++i)
466 t->sighand->action[i].sa.sa_handler = SIG_IGN;
472 * Flush all handlers for a task.
476 flush_signal_handlers(struct task_struct *t, int force_default)
479 struct k_sigaction *ka = &t->sighand->action[0];
480 for (i = _NSIG ; i != 0 ; i--) {
481 if (force_default || ka->sa.sa_handler != SIG_IGN)
482 ka->sa.sa_handler = SIG_DFL;
484 #ifdef __ARCH_HAS_SA_RESTORER
485 ka->sa.sa_restorer = NULL;
487 sigemptyset(&ka->sa.sa_mask);
492 int unhandled_signal(struct task_struct *tsk, int sig)
494 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
495 if (is_global_init(tsk))
497 if (handler != SIG_IGN && handler != SIG_DFL)
499 /* if ptraced, let the tracer determine */
504 * Notify the system that a driver wants to block all signals for this
505 * process, and wants to be notified if any signals at all were to be
506 * sent/acted upon. If the notifier routine returns non-zero, then the
507 * signal will be acted upon after all. If the notifier routine returns 0,
508 * then then signal will be blocked. Only one block per process is
509 * allowed. priv is a pointer to private data that the notifier routine
510 * can use to determine if the signal should be blocked or not.
513 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
517 spin_lock_irqsave(¤t->sighand->siglock, flags);
518 current->notifier_mask = mask;
519 current->notifier_data = priv;
520 current->notifier = notifier;
521 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
524 /* Notify the system that blocking has ended. */
527 unblock_all_signals(void)
531 spin_lock_irqsave(¤t->sighand->siglock, flags);
532 current->notifier = NULL;
533 current->notifier_data = NULL;
535 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
538 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
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);
563 (first->flags & SIGQUEUE_PREALLOC) &&
564 (info->si_code == SI_TIMER) &&
565 (info->si_sys_private);
567 __sigqueue_free(first);
570 * Ok, it wasn't in the queue. This must be
571 * a fast-pathed signal or we must have been
572 * out of queue space. So zero out the info.
574 info->si_signo = sig;
576 info->si_code = SI_USER;
582 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
583 siginfo_t *info, bool *resched_timer)
585 int sig = next_signal(pending, mask);
588 if (current->notifier) {
589 if (sigismember(current->notifier_mask, sig)) {
590 if (!(current->notifier)(current->notifier_data)) {
591 clear_thread_flag(TIF_SIGPENDING);
597 collect_signal(sig, pending, info, resched_timer);
604 * Dequeue a signal and return the element to the caller, which is
605 * expected to free it.
607 * All callers have to hold the siglock.
609 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
611 bool resched_timer = false;
614 /* We only dequeue private signals from ourselves, we don't let
615 * signalfd steal them
617 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
619 signr = __dequeue_signal(&tsk->signal->shared_pending,
620 mask, info, &resched_timer);
624 * itimers are process shared and we restart periodic
625 * itimers in the signal delivery path to prevent DoS
626 * attacks in the high resolution timer case. This is
627 * compliant with the old way of self-restarting
628 * itimers, as the SIGALRM is a legacy signal and only
629 * queued once. Changing the restart behaviour to
630 * restart the timer in the signal dequeue path is
631 * reducing the timer noise on heavy loaded !highres
634 if (unlikely(signr == SIGALRM)) {
635 struct hrtimer *tmr = &tsk->signal->real_timer;
637 if (!hrtimer_is_queued(tmr) &&
638 tsk->signal->it_real_incr.tv64 != 0) {
639 hrtimer_forward(tmr, tmr->base->get_time(),
640 tsk->signal->it_real_incr);
641 hrtimer_restart(tmr);
650 if (unlikely(sig_kernel_stop(signr))) {
652 * Set a marker that we have dequeued a stop signal. Our
653 * caller might release the siglock and then the pending
654 * stop signal it is about to process is no longer in the
655 * pending bitmasks, but must still be cleared by a SIGCONT
656 * (and overruled by a SIGKILL). So those cases clear this
657 * shared flag after we've set it. Note that this flag may
658 * remain set after the signal we return is ignored or
659 * handled. That doesn't matter because its only purpose
660 * is to alert stop-signal processing code when another
661 * processor has come along and cleared the flag.
663 current->jobctl |= JOBCTL_STOP_DEQUEUED;
667 * Release the siglock to ensure proper locking order
668 * of timer locks outside of siglocks. Note, we leave
669 * irqs disabled here, since the posix-timers code is
670 * about to disable them again anyway.
672 spin_unlock(&tsk->sighand->siglock);
673 do_schedule_next_timer(info);
674 spin_lock(&tsk->sighand->siglock);
680 * Tell a process that it has a new active signal..
682 * NOTE! we rely on the previous spin_lock to
683 * lock interrupts for us! We can only be called with
684 * "siglock" held, and the local interrupt must
685 * have been disabled when that got acquired!
687 * No need to set need_resched since signal event passing
688 * goes through ->blocked
690 void signal_wake_up_state(struct task_struct *t, unsigned int state)
692 set_tsk_thread_flag(t, TIF_SIGPENDING);
694 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
695 * case. We don't check t->state here because there is a race with it
696 * executing another processor and just now entering stopped state.
697 * By using wake_up_state, we ensure the process will wake up and
698 * handle its death signal.
700 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
705 * Remove signals in mask from the pending set and queue.
706 * Returns 1 if any signals were found.
708 * All callers must be holding the siglock.
710 * This version takes a sigset mask and looks at all signals,
711 * not just those in the first mask word.
713 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
715 struct sigqueue *q, *n;
718 sigandsets(&m, mask, &s->signal);
719 if (sigisemptyset(&m))
722 sigandnsets(&s->signal, &s->signal, mask);
723 list_for_each_entry_safe(q, n, &s->list, list) {
724 if (sigismember(mask, q->info.si_signo)) {
725 list_del_init(&q->list);
732 * Remove signals in mask from the pending set and queue.
733 * Returns 1 if any signals were found.
735 * All callers must be holding the siglock.
737 static int rm_from_queue(unsigned long mask, struct sigpending *s)
739 struct sigqueue *q, *n;
741 if (!sigtestsetmask(&s->signal, mask))
744 sigdelsetmask(&s->signal, mask);
745 list_for_each_entry_safe(q, n, &s->list, list) {
746 if (q->info.si_signo < SIGRTMIN &&
747 (mask & sigmask(q->info.si_signo))) {
748 list_del_init(&q->list);
755 static inline int is_si_special(const struct siginfo *info)
757 return info <= SEND_SIG_FORCED;
760 static inline bool si_fromuser(const struct siginfo *info)
762 return info == SEND_SIG_NOINFO ||
763 (!is_si_special(info) && SI_FROMUSER(info));
767 * called with RCU read lock from check_kill_permission()
769 static int kill_ok_by_cred(struct task_struct *t)
771 const struct cred *cred = current_cred();
772 const struct cred *tcred = __task_cred(t);
774 if (cred->user->user_ns == tcred->user->user_ns &&
775 (cred->euid == tcred->suid ||
776 cred->euid == tcred->uid ||
777 cred->uid == tcred->suid ||
778 cred->uid == tcred->uid))
781 if (ns_capable(tcred->user->user_ns, CAP_KILL))
788 * Bad permissions for sending the signal
789 * - the caller must hold the RCU read lock
791 static int check_kill_permission(int sig, struct siginfo *info,
792 struct task_struct *t)
797 if (!valid_signal(sig))
800 if (!si_fromuser(info))
803 error = audit_signal_info(sig, t); /* Let audit system see the signal */
807 if (!same_thread_group(current, t) &&
808 !kill_ok_by_cred(t)) {
811 sid = task_session(t);
813 * We don't return the error if sid == NULL. The
814 * task was unhashed, the caller must notice this.
816 if (!sid || sid == task_session(current))
823 return security_task_kill(t, info, sig, 0);
827 * ptrace_trap_notify - schedule trap to notify ptracer
828 * @t: tracee wanting to notify tracer
830 * This function schedules sticky ptrace trap which is cleared on the next
831 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
834 * If @t is running, STOP trap will be taken. If trapped for STOP and
835 * ptracer is listening for events, tracee is woken up so that it can
836 * re-trap for the new event. If trapped otherwise, STOP trap will be
837 * eventually taken without returning to userland after the existing traps
838 * are finished by PTRACE_CONT.
841 * Must be called with @task->sighand->siglock held.
843 static void ptrace_trap_notify(struct task_struct *t)
845 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
846 assert_spin_locked(&t->sighand->siglock);
848 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
849 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
853 * Handle magic process-wide effects of stop/continue signals. Unlike
854 * the signal actions, these happen immediately at signal-generation
855 * time regardless of blocking, ignoring, or handling. This does the
856 * actual continuing for SIGCONT, but not the actual stopping for stop
857 * signals. The process stop is done as a signal action for SIG_DFL.
859 * Returns true if the signal should be actually delivered, otherwise
860 * it should be dropped.
862 static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
864 struct signal_struct *signal = p->signal;
865 struct task_struct *t;
867 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
869 * The process is in the middle of dying, nothing to do.
871 } else if (sig_kernel_stop(sig)) {
873 * This is a stop signal. Remove SIGCONT from all queues.
875 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
878 rm_from_queue(sigmask(SIGCONT), &t->pending);
879 } while_each_thread(p, t);
880 } else if (sig == SIGCONT) {
883 * Remove all stop signals from all queues, wake all threads.
885 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
888 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
889 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
890 if (likely(!(t->ptrace & PT_SEIZED)))
891 wake_up_state(t, __TASK_STOPPED);
893 ptrace_trap_notify(t);
894 } while_each_thread(p, t);
897 * Notify the parent with CLD_CONTINUED if we were stopped.
899 * If we were in the middle of a group stop, we pretend it
900 * was already finished, and then continued. Since SIGCHLD
901 * doesn't queue we report only CLD_STOPPED, as if the next
902 * CLD_CONTINUED was dropped.
905 if (signal->flags & SIGNAL_STOP_STOPPED)
906 why |= SIGNAL_CLD_CONTINUED;
907 else if (signal->group_stop_count)
908 why |= SIGNAL_CLD_STOPPED;
912 * The first thread which returns from do_signal_stop()
913 * will take ->siglock, notice SIGNAL_CLD_MASK, and
914 * notify its parent. See get_signal_to_deliver().
916 signal->flags = why | SIGNAL_STOP_CONTINUED;
917 signal->group_stop_count = 0;
918 signal->group_exit_code = 0;
922 return !sig_ignored(p, sig, from_ancestor_ns);
926 * Test if P wants to take SIG. After we've checked all threads with this,
927 * it's equivalent to finding no threads not blocking SIG. Any threads not
928 * blocking SIG were ruled out because they are not running and already
929 * have pending signals. Such threads will dequeue from the shared queue
930 * as soon as they're available, so putting the signal on the shared queue
931 * will be equivalent to sending it to one such thread.
933 static inline int wants_signal(int sig, struct task_struct *p)
935 if (sigismember(&p->blocked, sig))
937 if (p->flags & PF_EXITING)
941 if (task_is_stopped_or_traced(p))
943 return task_curr(p) || !signal_pending(p);
946 static void complete_signal(int sig, struct task_struct *p, int group)
948 struct signal_struct *signal = p->signal;
949 struct task_struct *t;
952 * Now find a thread we can wake up to take the signal off the queue.
954 * If the main thread wants the signal, it gets first crack.
955 * Probably the least surprising to the average bear.
957 if (wants_signal(sig, p))
959 else if (!group || thread_group_empty(p))
961 * There is just one thread and it does not need to be woken.
962 * It will dequeue unblocked signals before it runs again.
967 * Otherwise try to find a suitable thread.
969 t = signal->curr_target;
970 while (!wants_signal(sig, t)) {
972 if (t == signal->curr_target)
974 * No thread needs to be woken.
975 * Any eligible threads will see
976 * the signal in the queue soon.
980 signal->curr_target = t;
984 * Found a killable thread. If the signal will be fatal,
985 * then start taking the whole group down immediately.
987 if (sig_fatal(p, sig) &&
988 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
989 !sigismember(&t->real_blocked, sig) &&
990 (sig == SIGKILL || !t->ptrace)) {
992 * This signal will be fatal to the whole group.
994 if (!sig_kernel_coredump(sig)) {
996 * Start a group exit and wake everybody up.
997 * This way we don't have other threads
998 * running and doing things after a slower
999 * thread has the fatal signal pending.
1001 signal->flags = SIGNAL_GROUP_EXIT;
1002 signal->group_exit_code = sig;
1003 signal->group_stop_count = 0;
1006 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1007 sigaddset(&t->pending.signal, SIGKILL);
1008 signal_wake_up(t, 1);
1009 } while_each_thread(p, t);
1015 * The signal is already in the shared-pending queue.
1016 * Tell the chosen thread to wake up and dequeue it.
1018 signal_wake_up(t, sig == SIGKILL);
1022 static inline int legacy_queue(struct sigpending *signals, int sig)
1024 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1027 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1028 int group, int from_ancestor_ns)
1030 struct sigpending *pending;
1032 int override_rlimit;
1034 trace_signal_generate(sig, info, t);
1036 assert_spin_locked(&t->sighand->siglock);
1038 if (!prepare_signal(sig, t, from_ancestor_ns))
1041 pending = group ? &t->signal->shared_pending : &t->pending;
1043 * Short-circuit ignored signals and support queuing
1044 * exactly one non-rt signal, so that we can get more
1045 * detailed information about the cause of the signal.
1047 if (legacy_queue(pending, sig))
1050 * fast-pathed signals for kernel-internal things like SIGSTOP
1053 if (info == SEND_SIG_FORCED)
1057 * Real-time signals must be queued if sent by sigqueue, or
1058 * some other real-time mechanism. It is implementation
1059 * defined whether kill() does so. We attempt to do so, on
1060 * the principle of least surprise, but since kill is not
1061 * allowed to fail with EAGAIN when low on memory we just
1062 * make sure at least one signal gets delivered and don't
1063 * pass on the info struct.
1066 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1068 override_rlimit = 0;
1070 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1073 list_add_tail(&q->list, &pending->list);
1074 switch ((unsigned long) info) {
1075 case (unsigned long) SEND_SIG_NOINFO:
1076 q->info.si_signo = sig;
1077 q->info.si_errno = 0;
1078 q->info.si_code = SI_USER;
1079 q->info.si_pid = task_tgid_nr_ns(current,
1080 task_active_pid_ns(t));
1081 q->info.si_uid = current_uid();
1083 case (unsigned long) SEND_SIG_PRIV:
1084 q->info.si_signo = sig;
1085 q->info.si_errno = 0;
1086 q->info.si_code = SI_KERNEL;
1091 copy_siginfo(&q->info, info);
1092 if (from_ancestor_ns)
1096 } else if (!is_si_special(info)) {
1097 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1099 * Queue overflow, abort. We may abort if the
1100 * signal was rt and sent by user using something
1101 * other than kill().
1103 trace_signal_overflow_fail(sig, group, info);
1107 * This is a silent loss of information. We still
1108 * send the signal, but the *info bits are lost.
1110 trace_signal_lose_info(sig, group, info);
1115 signalfd_notify(t, sig);
1116 sigaddset(&pending->signal, sig);
1117 complete_signal(sig, t, group);
1121 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1124 int from_ancestor_ns = 0;
1126 #ifdef CONFIG_PID_NS
1127 from_ancestor_ns = si_fromuser(info) &&
1128 !task_pid_nr_ns(current, task_active_pid_ns(t));
1131 return __send_signal(sig, info, t, group, from_ancestor_ns);
1134 static void print_fatal_signal(struct pt_regs *regs, int signr)
1136 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1137 current->comm, task_pid_nr(current), signr);
1139 #if defined(__i386__) && !defined(__arch_um__)
1140 printk("code at %08lx: ", regs->ip);
1143 for (i = 0; i < 16; i++) {
1146 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1148 printk("%02x ", insn);
1158 static int __init setup_print_fatal_signals(char *str)
1160 get_option (&str, &print_fatal_signals);
1165 __setup("print-fatal-signals=", setup_print_fatal_signals);
1168 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1170 return send_signal(sig, info, p, 1);
1174 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1176 return send_signal(sig, info, t, 0);
1179 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1182 unsigned long flags;
1185 if (lock_task_sighand(p, &flags)) {
1186 ret = send_signal(sig, info, p, group);
1187 unlock_task_sighand(p, &flags);
1194 * Force a signal that the process can't ignore: if necessary
1195 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1197 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1198 * since we do not want to have a signal handler that was blocked
1199 * be invoked when user space had explicitly blocked it.
1201 * We don't want to have recursive SIGSEGV's etc, for example,
1202 * that is why we also clear SIGNAL_UNKILLABLE.
1205 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1207 unsigned long int flags;
1208 int ret, blocked, ignored;
1209 struct k_sigaction *action;
1211 spin_lock_irqsave(&t->sighand->siglock, flags);
1212 action = &t->sighand->action[sig-1];
1213 ignored = action->sa.sa_handler == SIG_IGN;
1214 blocked = sigismember(&t->blocked, sig);
1215 if (blocked || ignored) {
1216 action->sa.sa_handler = SIG_DFL;
1218 sigdelset(&t->blocked, sig);
1219 recalc_sigpending_and_wake(t);
1222 if (action->sa.sa_handler == SIG_DFL)
1223 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1224 ret = specific_send_sig_info(sig, info, t);
1225 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1231 * Nuke all other threads in the group.
1233 int zap_other_threads(struct task_struct *p)
1235 struct task_struct *t = p;
1238 p->signal->group_stop_count = 0;
1240 while_each_thread(p, t) {
1241 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1244 /* Don't bother with already dead threads */
1247 sigaddset(&t->pending.signal, SIGKILL);
1248 signal_wake_up(t, 1);
1254 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1255 unsigned long *flags)
1257 struct sighand_struct *sighand;
1260 local_irq_save(*flags);
1262 sighand = rcu_dereference(tsk->sighand);
1263 if (unlikely(sighand == NULL)) {
1265 local_irq_restore(*flags);
1269 spin_lock(&sighand->siglock);
1270 if (likely(sighand == tsk->sighand)) {
1274 spin_unlock(&sighand->siglock);
1276 local_irq_restore(*flags);
1281 EXPORT_SYMBOL_GPL(__lock_task_sighand);
1284 * send signal info to all the members of a group
1286 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1291 ret = check_kill_permission(sig, info, p);
1295 ret = do_send_sig_info(sig, info, p, true);
1301 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1302 * control characters do (^C, ^Z etc)
1303 * - the caller must hold at least a readlock on tasklist_lock
1305 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1307 struct task_struct *p = NULL;
1308 int retval, success;
1312 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1313 int err = group_send_sig_info(sig, info, p);
1316 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1317 return success ? 0 : retval;
1320 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1323 struct task_struct *p;
1327 p = pid_task(pid, PIDTYPE_PID);
1329 error = group_send_sig_info(sig, info, p);
1330 if (unlikely(error == -ESRCH))
1332 * The task was unhashed in between, try again.
1333 * If it is dead, pid_task() will return NULL,
1334 * if we race with de_thread() it will find the
1344 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1348 error = kill_pid_info(sig, info, find_vpid(pid));
1353 static int kill_as_cred_perm(const struct cred *cred,
1354 struct task_struct *target)
1356 const struct cred *pcred = __task_cred(target);
1357 if (cred->user_ns != pcred->user_ns)
1359 if (cred->euid != pcred->suid && cred->euid != pcred->uid &&
1360 cred->uid != pcred->suid && cred->uid != pcred->uid)
1365 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1366 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1367 const struct cred *cred, u32 secid)
1370 struct task_struct *p;
1371 unsigned long flags;
1373 if (!valid_signal(sig))
1377 p = pid_task(pid, PIDTYPE_PID);
1382 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1386 ret = security_task_kill(p, info, sig, secid);
1391 if (lock_task_sighand(p, &flags)) {
1392 ret = __send_signal(sig, info, p, 1, 0);
1393 unlock_task_sighand(p, &flags);
1401 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1404 * kill_something_info() interprets pid in interesting ways just like kill(2).
1406 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1407 * is probably wrong. Should make it like BSD or SYSV.
1410 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1416 ret = kill_pid_info(sig, info, find_vpid(pid));
1421 read_lock(&tasklist_lock);
1423 ret = __kill_pgrp_info(sig, info,
1424 pid ? find_vpid(-pid) : task_pgrp(current));
1426 int retval = 0, count = 0;
1427 struct task_struct * p;
1429 for_each_process(p) {
1430 if (task_pid_vnr(p) > 1 &&
1431 !same_thread_group(p, current)) {
1432 int err = group_send_sig_info(sig, info, p);
1438 ret = count ? retval : -ESRCH;
1440 read_unlock(&tasklist_lock);
1446 * These are for backward compatibility with the rest of the kernel source.
1449 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1452 * Make sure legacy kernel users don't send in bad values
1453 * (normal paths check this in check_kill_permission).
1455 if (!valid_signal(sig))
1458 return do_send_sig_info(sig, info, p, false);
1461 #define __si_special(priv) \
1462 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1465 send_sig(int sig, struct task_struct *p, int priv)
1467 return send_sig_info(sig, __si_special(priv), p);
1471 force_sig(int sig, struct task_struct *p)
1473 force_sig_info(sig, SEND_SIG_PRIV, p);
1477 * When things go south during signal handling, we
1478 * will force a SIGSEGV. And if the signal that caused
1479 * the problem was already a SIGSEGV, we'll want to
1480 * make sure we don't even try to deliver the signal..
1483 force_sigsegv(int sig, struct task_struct *p)
1485 if (sig == SIGSEGV) {
1486 unsigned long flags;
1487 spin_lock_irqsave(&p->sighand->siglock, flags);
1488 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1489 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1491 force_sig(SIGSEGV, p);
1495 int kill_pgrp(struct pid *pid, int sig, int priv)
1499 read_lock(&tasklist_lock);
1500 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1501 read_unlock(&tasklist_lock);
1505 EXPORT_SYMBOL(kill_pgrp);
1507 int kill_pid(struct pid *pid, int sig, int priv)
1509 return kill_pid_info(sig, __si_special(priv), pid);
1511 EXPORT_SYMBOL(kill_pid);
1514 * These functions support sending signals using preallocated sigqueue
1515 * structures. This is needed "because realtime applications cannot
1516 * afford to lose notifications of asynchronous events, like timer
1517 * expirations or I/O completions". In the case of POSIX Timers
1518 * we allocate the sigqueue structure from the timer_create. If this
1519 * allocation fails we are able to report the failure to the application
1520 * with an EAGAIN error.
1522 struct sigqueue *sigqueue_alloc(void)
1524 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1527 q->flags |= SIGQUEUE_PREALLOC;
1532 void sigqueue_free(struct sigqueue *q)
1534 unsigned long flags;
1535 spinlock_t *lock = ¤t->sighand->siglock;
1537 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1539 * We must hold ->siglock while testing q->list
1540 * to serialize with collect_signal() or with
1541 * __exit_signal()->flush_sigqueue().
1543 spin_lock_irqsave(lock, flags);
1544 q->flags &= ~SIGQUEUE_PREALLOC;
1546 * If it is queued it will be freed when dequeued,
1547 * like the "regular" sigqueue.
1549 if (!list_empty(&q->list))
1551 spin_unlock_irqrestore(lock, flags);
1557 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1559 int sig = q->info.si_signo;
1560 struct sigpending *pending;
1561 unsigned long flags;
1564 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1567 if (!likely(lock_task_sighand(t, &flags)))
1570 ret = 1; /* the signal is ignored */
1571 if (!prepare_signal(sig, t, 0))
1575 if (unlikely(!list_empty(&q->list))) {
1577 * If an SI_TIMER entry is already queue just increment
1578 * the overrun count.
1580 BUG_ON(q->info.si_code != SI_TIMER);
1581 q->info.si_overrun++;
1584 q->info.si_overrun = 0;
1586 signalfd_notify(t, sig);
1587 pending = group ? &t->signal->shared_pending : &t->pending;
1588 list_add_tail(&q->list, &pending->list);
1589 sigaddset(&pending->signal, sig);
1590 complete_signal(sig, t, group);
1592 unlock_task_sighand(t, &flags);
1598 * Let a parent know about the death of a child.
1599 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1601 * Returns true if our parent ignored us and so we've switched to
1604 bool do_notify_parent(struct task_struct *tsk, int sig)
1606 struct siginfo info;
1607 unsigned long flags;
1608 struct sighand_struct *psig;
1609 bool autoreap = false;
1613 /* do_notify_parent_cldstop should have been called instead. */
1614 BUG_ON(task_is_stopped_or_traced(tsk));
1616 BUG_ON(!tsk->ptrace &&
1617 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1619 if (sig != SIGCHLD) {
1621 * This is only possible if parent == real_parent.
1622 * Check if it has changed security domain.
1624 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1628 info.si_signo = sig;
1631 * we are under tasklist_lock here so our parent is tied to
1632 * us and cannot exit and release its namespace.
1634 * the only it can is to switch its nsproxy with sys_unshare,
1635 * bu uncharing pid namespaces is not allowed, so we'll always
1636 * see relevant namespace
1638 * write_lock() currently calls preempt_disable() which is the
1639 * same as rcu_read_lock(), but according to Oleg, this is not
1640 * correct to rely on this
1643 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1644 info.si_uid = __task_cred(tsk)->uid;
1647 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1648 tsk->signal->utime));
1649 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1650 tsk->signal->stime));
1652 info.si_status = tsk->exit_code & 0x7f;
1653 if (tsk->exit_code & 0x80)
1654 info.si_code = CLD_DUMPED;
1655 else if (tsk->exit_code & 0x7f)
1656 info.si_code = CLD_KILLED;
1658 info.si_code = CLD_EXITED;
1659 info.si_status = tsk->exit_code >> 8;
1662 psig = tsk->parent->sighand;
1663 spin_lock_irqsave(&psig->siglock, flags);
1664 if (!tsk->ptrace && sig == SIGCHLD &&
1665 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1666 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1668 * We are exiting and our parent doesn't care. POSIX.1
1669 * defines special semantics for setting SIGCHLD to SIG_IGN
1670 * or setting the SA_NOCLDWAIT flag: we should be reaped
1671 * automatically and not left for our parent's wait4 call.
1672 * Rather than having the parent do it as a magic kind of
1673 * signal handler, we just set this to tell do_exit that we
1674 * can be cleaned up without becoming a zombie. Note that
1675 * we still call __wake_up_parent in this case, because a
1676 * blocked sys_wait4 might now return -ECHILD.
1678 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1679 * is implementation-defined: we do (if you don't want
1680 * it, just use SIG_IGN instead).
1683 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1686 if (valid_signal(sig) && sig)
1687 __group_send_sig_info(sig, &info, tsk->parent);
1688 __wake_up_parent(tsk, tsk->parent);
1689 spin_unlock_irqrestore(&psig->siglock, flags);
1695 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1696 * @tsk: task reporting the state change
1697 * @for_ptracer: the notification is for ptracer
1698 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1700 * Notify @tsk's parent that the stopped/continued state has changed. If
1701 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1702 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1705 * Must be called with tasklist_lock at least read locked.
1707 static void do_notify_parent_cldstop(struct task_struct *tsk,
1708 bool for_ptracer, int why)
1710 struct siginfo info;
1711 unsigned long flags;
1712 struct task_struct *parent;
1713 struct sighand_struct *sighand;
1716 parent = tsk->parent;
1718 tsk = tsk->group_leader;
1719 parent = tsk->real_parent;
1722 info.si_signo = SIGCHLD;
1725 * see comment in do_notify_parent() about the following 4 lines
1728 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1729 info.si_uid = __task_cred(tsk)->uid;
1732 info.si_utime = cputime_to_clock_t(tsk->utime);
1733 info.si_stime = cputime_to_clock_t(tsk->stime);
1738 info.si_status = SIGCONT;
1741 info.si_status = tsk->signal->group_exit_code & 0x7f;
1744 info.si_status = tsk->exit_code & 0x7f;
1750 sighand = parent->sighand;
1751 spin_lock_irqsave(&sighand->siglock, flags);
1752 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1753 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1754 __group_send_sig_info(SIGCHLD, &info, parent);
1756 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1758 __wake_up_parent(tsk, parent);
1759 spin_unlock_irqrestore(&sighand->siglock, flags);
1762 static inline int may_ptrace_stop(void)
1764 if (!likely(current->ptrace))
1767 * Are we in the middle of do_coredump?
1768 * If so and our tracer is also part of the coredump stopping
1769 * is a deadlock situation, and pointless because our tracer
1770 * is dead so don't allow us to stop.
1771 * If SIGKILL was already sent before the caller unlocked
1772 * ->siglock we must see ->core_state != NULL. Otherwise it
1773 * is safe to enter schedule().
1775 * This is almost outdated, a task with the pending SIGKILL can't
1776 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1777 * after SIGKILL was already dequeued.
1779 if (unlikely(current->mm->core_state) &&
1780 unlikely(current->mm == current->parent->mm))
1787 * Return non-zero if there is a SIGKILL that should be waking us up.
1788 * Called with the siglock held.
1790 static int sigkill_pending(struct task_struct *tsk)
1792 return sigismember(&tsk->pending.signal, SIGKILL) ||
1793 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1797 * This must be called with current->sighand->siglock held.
1799 * This should be the path for all ptrace stops.
1800 * We always set current->last_siginfo while stopped here.
1801 * That makes it a way to test a stopped process for
1802 * being ptrace-stopped vs being job-control-stopped.
1804 * If we actually decide not to stop at all because the tracer
1805 * is gone, we keep current->exit_code unless clear_code.
1807 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1808 __releases(¤t->sighand->siglock)
1809 __acquires(¤t->sighand->siglock)
1811 bool gstop_done = false;
1813 if (arch_ptrace_stop_needed(exit_code, info)) {
1815 * The arch code has something special to do before a
1816 * ptrace stop. This is allowed to block, e.g. for faults
1817 * on user stack pages. We can't keep the siglock while
1818 * calling arch_ptrace_stop, so we must release it now.
1819 * To preserve proper semantics, we must do this before
1820 * any signal bookkeeping like checking group_stop_count.
1821 * Meanwhile, a SIGKILL could come in before we retake the
1822 * siglock. That must prevent us from sleeping in TASK_TRACED.
1823 * So after regaining the lock, we must check for SIGKILL.
1825 spin_unlock_irq(¤t->sighand->siglock);
1826 arch_ptrace_stop(exit_code, info);
1827 spin_lock_irq(¤t->sighand->siglock);
1828 if (sigkill_pending(current))
1833 * We're committing to trapping. TRACED should be visible before
1834 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1835 * Also, transition to TRACED and updates to ->jobctl should be
1836 * atomic with respect to siglock and should be done after the arch
1837 * hook as siglock is released and regrabbed across it.
1839 set_current_state(TASK_TRACED);
1841 current->last_siginfo = info;
1842 current->exit_code = exit_code;
1845 * If @why is CLD_STOPPED, we're trapping to participate in a group
1846 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1847 * across siglock relocks since INTERRUPT was scheduled, PENDING
1848 * could be clear now. We act as if SIGCONT is received after
1849 * TASK_TRACED is entered - ignore it.
1851 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1852 gstop_done = task_participate_group_stop(current);
1854 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1855 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1856 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1857 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1859 /* entering a trap, clear TRAPPING */
1860 task_clear_jobctl_trapping(current);
1862 spin_unlock_irq(¤t->sighand->siglock);
1863 read_lock(&tasklist_lock);
1864 if (may_ptrace_stop()) {
1866 * Notify parents of the stop.
1868 * While ptraced, there are two parents - the ptracer and
1869 * the real_parent of the group_leader. The ptracer should
1870 * know about every stop while the real parent is only
1871 * interested in the completion of group stop. The states
1872 * for the two don't interact with each other. Notify
1873 * separately unless they're gonna be duplicates.
1875 do_notify_parent_cldstop(current, true, why);
1876 if (gstop_done && ptrace_reparented(current))
1877 do_notify_parent_cldstop(current, false, why);
1880 * Don't want to allow preemption here, because
1881 * sys_ptrace() needs this task to be inactive.
1883 * XXX: implement read_unlock_no_resched().
1886 read_unlock(&tasklist_lock);
1887 preempt_enable_no_resched();
1891 * By the time we got the lock, our tracer went away.
1892 * Don't drop the lock yet, another tracer may come.
1894 * If @gstop_done, the ptracer went away between group stop
1895 * completion and here. During detach, it would have set
1896 * JOBCTL_STOP_PENDING on us and we'll re-enter
1897 * TASK_STOPPED in do_signal_stop() on return, so notifying
1898 * the real parent of the group stop completion is enough.
1901 do_notify_parent_cldstop(current, false, why);
1903 /* tasklist protects us from ptrace_freeze_traced() */
1904 __set_current_state(TASK_RUNNING);
1906 current->exit_code = 0;
1907 read_unlock(&tasklist_lock);
1911 * While in TASK_TRACED, we were considered "frozen enough".
1912 * Now that we woke up, it's crucial if we're supposed to be
1913 * frozen that we freeze now before running anything substantial.
1918 * We are back. Now reacquire the siglock before touching
1919 * last_siginfo, so that we are sure to have synchronized with
1920 * any signal-sending on another CPU that wants to examine it.
1922 spin_lock_irq(¤t->sighand->siglock);
1923 current->last_siginfo = NULL;
1925 /* LISTENING can be set only during STOP traps, clear it */
1926 current->jobctl &= ~JOBCTL_LISTENING;
1929 * Queued signals ignored us while we were stopped for tracing.
1930 * So check for any that we should take before resuming user mode.
1931 * This sets TIF_SIGPENDING, but never clears it.
1933 recalc_sigpending_tsk(current);
1936 static void ptrace_do_notify(int signr, int exit_code, int why)
1940 memset(&info, 0, sizeof info);
1941 info.si_signo = signr;
1942 info.si_code = exit_code;
1943 info.si_pid = task_pid_vnr(current);
1944 info.si_uid = current_uid();
1946 /* Let the debugger run. */
1947 ptrace_stop(exit_code, why, 1, &info);
1950 void ptrace_notify(int exit_code)
1952 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1954 spin_lock_irq(¤t->sighand->siglock);
1955 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1956 spin_unlock_irq(¤t->sighand->siglock);
1960 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1961 * @signr: signr causing group stop if initiating
1963 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1964 * and participate in it. If already set, participate in the existing
1965 * group stop. If participated in a group stop (and thus slept), %true is
1966 * returned with siglock released.
1968 * If ptraced, this function doesn't handle stop itself. Instead,
1969 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1970 * untouched. The caller must ensure that INTERRUPT trap handling takes
1971 * places afterwards.
1974 * Must be called with @current->sighand->siglock held, which is released
1978 * %false if group stop is already cancelled or ptrace trap is scheduled.
1979 * %true if participated in group stop.
1981 static bool do_signal_stop(int signr)
1982 __releases(¤t->sighand->siglock)
1984 struct signal_struct *sig = current->signal;
1986 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1987 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1988 struct task_struct *t;
1990 /* signr will be recorded in task->jobctl for retries */
1991 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1993 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1994 unlikely(signal_group_exit(sig)))
1997 * There is no group stop already in progress. We must
2000 * While ptraced, a task may be resumed while group stop is
2001 * still in effect and then receive a stop signal and
2002 * initiate another group stop. This deviates from the
2003 * usual behavior as two consecutive stop signals can't
2004 * cause two group stops when !ptraced. That is why we
2005 * also check !task_is_stopped(t) below.
2007 * The condition can be distinguished by testing whether
2008 * SIGNAL_STOP_STOPPED is already set. Don't generate
2009 * group_exit_code in such case.
2011 * This is not necessary for SIGNAL_STOP_CONTINUED because
2012 * an intervening stop signal is required to cause two
2013 * continued events regardless of ptrace.
2015 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2016 sig->group_exit_code = signr;
2018 sig->group_stop_count = 0;
2020 if (task_set_jobctl_pending(current, signr | gstop))
2021 sig->group_stop_count++;
2023 for (t = next_thread(current); t != current;
2024 t = next_thread(t)) {
2026 * Setting state to TASK_STOPPED for a group
2027 * stop is always done with the siglock held,
2028 * so this check has no races.
2030 if (!task_is_stopped(t) &&
2031 task_set_jobctl_pending(t, signr | gstop)) {
2032 sig->group_stop_count++;
2033 if (likely(!(t->ptrace & PT_SEIZED)))
2034 signal_wake_up(t, 0);
2036 ptrace_trap_notify(t);
2041 if (likely(!current->ptrace)) {
2045 * If there are no other threads in the group, or if there
2046 * is a group stop in progress and we are the last to stop,
2047 * report to the parent.
2049 if (task_participate_group_stop(current))
2050 notify = CLD_STOPPED;
2052 __set_current_state(TASK_STOPPED);
2053 spin_unlock_irq(¤t->sighand->siglock);
2056 * Notify the parent of the group stop completion. Because
2057 * we're not holding either the siglock or tasklist_lock
2058 * here, ptracer may attach inbetween; however, this is for
2059 * group stop and should always be delivered to the real
2060 * parent of the group leader. The new ptracer will get
2061 * its notification when this task transitions into
2065 read_lock(&tasklist_lock);
2066 do_notify_parent_cldstop(current, false, notify);
2067 read_unlock(&tasklist_lock);
2070 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2075 * While ptraced, group stop is handled by STOP trap.
2076 * Schedule it and let the caller deal with it.
2078 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2084 * do_jobctl_trap - take care of ptrace jobctl traps
2086 * When PT_SEIZED, it's used for both group stop and explicit
2087 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2088 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2089 * the stop signal; otherwise, %SIGTRAP.
2091 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2092 * number as exit_code and no siginfo.
2095 * Must be called with @current->sighand->siglock held, which may be
2096 * released and re-acquired before returning with intervening sleep.
2098 static void do_jobctl_trap(void)
2100 struct signal_struct *signal = current->signal;
2101 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2103 if (current->ptrace & PT_SEIZED) {
2104 if (!signal->group_stop_count &&
2105 !(signal->flags & SIGNAL_STOP_STOPPED))
2107 WARN_ON_ONCE(!signr);
2108 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2111 WARN_ON_ONCE(!signr);
2112 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2113 current->exit_code = 0;
2117 static int ptrace_signal(int signr, siginfo_t *info,
2118 struct pt_regs *regs, void *cookie)
2120 ptrace_signal_deliver(regs, cookie);
2122 * We do not check sig_kernel_stop(signr) but set this marker
2123 * unconditionally because we do not know whether debugger will
2124 * change signr. This flag has no meaning unless we are going
2125 * to stop after return from ptrace_stop(). In this case it will
2126 * be checked in do_signal_stop(), we should only stop if it was
2127 * not cleared by SIGCONT while we were sleeping. See also the
2128 * comment in dequeue_signal().
2130 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2131 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2133 /* We're back. Did the debugger cancel the sig? */
2134 signr = current->exit_code;
2138 current->exit_code = 0;
2141 * Update the siginfo structure if the signal has
2142 * changed. If the debugger wanted something
2143 * specific in the siginfo structure then it should
2144 * have updated *info via PTRACE_SETSIGINFO.
2146 if (signr != info->si_signo) {
2147 info->si_signo = signr;
2149 info->si_code = SI_USER;
2150 info->si_pid = task_pid_vnr(current->parent);
2151 info->si_uid = task_uid(current->parent);
2154 /* If the (new) signal is now blocked, requeue it. */
2155 if (sigismember(¤t->blocked, signr)) {
2156 specific_send_sig_info(signr, info, current);
2163 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2164 struct pt_regs *regs, void *cookie)
2166 struct sighand_struct *sighand = current->sighand;
2167 struct signal_struct *signal = current->signal;
2172 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2173 * While in TASK_STOPPED, we were considered "frozen enough".
2174 * Now that we woke up, it's crucial if we're supposed to be
2175 * frozen that we freeze now before running anything substantial.
2179 spin_lock_irq(&sighand->siglock);
2181 * Every stopped thread goes here after wakeup. Check to see if
2182 * we should notify the parent, prepare_signal(SIGCONT) encodes
2183 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2185 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2188 if (signal->flags & SIGNAL_CLD_CONTINUED)
2189 why = CLD_CONTINUED;
2193 signal->flags &= ~SIGNAL_CLD_MASK;
2195 spin_unlock_irq(&sighand->siglock);
2198 * Notify the parent that we're continuing. This event is
2199 * always per-process and doesn't make whole lot of sense
2200 * for ptracers, who shouldn't consume the state via
2201 * wait(2) either, but, for backward compatibility, notify
2202 * the ptracer of the group leader too unless it's gonna be
2205 read_lock(&tasklist_lock);
2206 do_notify_parent_cldstop(current, false, why);
2208 if (ptrace_reparented(current->group_leader))
2209 do_notify_parent_cldstop(current->group_leader,
2211 read_unlock(&tasklist_lock);
2217 struct k_sigaction *ka;
2219 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2223 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2225 spin_unlock_irq(&sighand->siglock);
2229 signr = dequeue_signal(current, ¤t->blocked, info);
2232 break; /* will return 0 */
2234 if (unlikely(current->ptrace) && signr != SIGKILL) {
2235 signr = ptrace_signal(signr, info,
2241 ka = &sighand->action[signr-1];
2243 /* Trace actually delivered signals. */
2244 trace_signal_deliver(signr, info, ka);
2246 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2248 if (ka->sa.sa_handler != SIG_DFL) {
2249 /* Run the handler. */
2252 if (ka->sa.sa_flags & SA_ONESHOT)
2253 ka->sa.sa_handler = SIG_DFL;
2255 break; /* will return non-zero "signr" value */
2259 * Now we are doing the default action for this signal.
2261 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2265 * Global init gets no signals it doesn't want.
2266 * Container-init gets no signals it doesn't want from same
2269 * Note that if global/container-init sees a sig_kernel_only()
2270 * signal here, the signal must have been generated internally
2271 * or must have come from an ancestor namespace. In either
2272 * case, the signal cannot be dropped.
2274 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2275 !sig_kernel_only(signr))
2278 if (sig_kernel_stop(signr)) {
2280 * The default action is to stop all threads in
2281 * the thread group. The job control signals
2282 * do nothing in an orphaned pgrp, but SIGSTOP
2283 * always works. Note that siglock needs to be
2284 * dropped during the call to is_orphaned_pgrp()
2285 * because of lock ordering with tasklist_lock.
2286 * This allows an intervening SIGCONT to be posted.
2287 * We need to check for that and bail out if necessary.
2289 if (signr != SIGSTOP) {
2290 spin_unlock_irq(&sighand->siglock);
2292 /* signals can be posted during this window */
2294 if (is_current_pgrp_orphaned())
2297 spin_lock_irq(&sighand->siglock);
2300 if (likely(do_signal_stop(info->si_signo))) {
2301 /* It released the siglock. */
2306 * We didn't actually stop, due to a race
2307 * with SIGCONT or something like that.
2312 spin_unlock_irq(&sighand->siglock);
2315 * Anything else is fatal, maybe with a core dump.
2317 current->flags |= PF_SIGNALED;
2319 if (sig_kernel_coredump(signr)) {
2320 if (print_fatal_signals)
2321 print_fatal_signal(regs, info->si_signo);
2323 * If it was able to dump core, this kills all
2324 * other threads in the group and synchronizes with
2325 * their demise. If we lost the race with another
2326 * thread getting here, it set group_exit_code
2327 * first and our do_group_exit call below will use
2328 * that value and ignore the one we pass it.
2330 do_coredump(info->si_signo, info->si_signo, regs);
2334 * Death signals, no core dump.
2336 do_group_exit(info->si_signo);
2339 spin_unlock_irq(&sighand->siglock);
2344 * It could be that complete_signal() picked us to notify about the
2345 * group-wide signal. Other threads should be notified now to take
2346 * the shared signals in @which since we will not.
2348 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2351 struct task_struct *t;
2353 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2354 if (sigisemptyset(&retarget))
2358 while_each_thread(tsk, t) {
2359 if (t->flags & PF_EXITING)
2362 if (!has_pending_signals(&retarget, &t->blocked))
2364 /* Remove the signals this thread can handle. */
2365 sigandsets(&retarget, &retarget, &t->blocked);
2367 if (!signal_pending(t))
2368 signal_wake_up(t, 0);
2370 if (sigisemptyset(&retarget))
2375 void exit_signals(struct task_struct *tsk)
2380 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2381 tsk->flags |= PF_EXITING;
2385 spin_lock_irq(&tsk->sighand->siglock);
2387 * From now this task is not visible for group-wide signals,
2388 * see wants_signal(), do_signal_stop().
2390 tsk->flags |= PF_EXITING;
2391 if (!signal_pending(tsk))
2394 unblocked = tsk->blocked;
2395 signotset(&unblocked);
2396 retarget_shared_pending(tsk, &unblocked);
2398 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2399 task_participate_group_stop(tsk))
2400 group_stop = CLD_STOPPED;
2402 spin_unlock_irq(&tsk->sighand->siglock);
2405 * If group stop has completed, deliver the notification. This
2406 * should always go to the real parent of the group leader.
2408 if (unlikely(group_stop)) {
2409 read_lock(&tasklist_lock);
2410 do_notify_parent_cldstop(tsk, false, group_stop);
2411 read_unlock(&tasklist_lock);
2415 EXPORT_SYMBOL(recalc_sigpending);
2416 EXPORT_SYMBOL_GPL(dequeue_signal);
2417 EXPORT_SYMBOL(flush_signals);
2418 EXPORT_SYMBOL(force_sig);
2419 EXPORT_SYMBOL(send_sig);
2420 EXPORT_SYMBOL(send_sig_info);
2421 EXPORT_SYMBOL(sigprocmask);
2422 EXPORT_SYMBOL(block_all_signals);
2423 EXPORT_SYMBOL(unblock_all_signals);
2427 * System call entry points.
2431 * sys_restart_syscall - restart a system call
2433 SYSCALL_DEFINE0(restart_syscall)
2435 struct restart_block *restart = ¤t_thread_info()->restart_block;
2436 return restart->fn(restart);
2439 long do_no_restart_syscall(struct restart_block *param)
2444 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2446 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2447 sigset_t newblocked;
2448 /* A set of now blocked but previously unblocked signals. */
2449 sigandnsets(&newblocked, newset, ¤t->blocked);
2450 retarget_shared_pending(tsk, &newblocked);
2452 tsk->blocked = *newset;
2453 recalc_sigpending();
2457 * set_current_blocked - change current->blocked mask
2460 * It is wrong to change ->blocked directly, this helper should be used
2461 * to ensure the process can't miss a shared signal we are going to block.
2463 void set_current_blocked(const sigset_t *newset)
2465 struct task_struct *tsk = current;
2467 spin_lock_irq(&tsk->sighand->siglock);
2468 __set_task_blocked(tsk, newset);
2469 spin_unlock_irq(&tsk->sighand->siglock);
2473 * This is also useful for kernel threads that want to temporarily
2474 * (or permanently) block certain signals.
2476 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2477 * interface happily blocks "unblockable" signals like SIGKILL
2480 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2482 struct task_struct *tsk = current;
2485 /* Lockless, only current can change ->blocked, never from irq */
2487 *oldset = tsk->blocked;
2491 sigorsets(&newset, &tsk->blocked, set);
2494 sigandnsets(&newset, &tsk->blocked, set);
2503 set_current_blocked(&newset);
2508 * sys_rt_sigprocmask - change the list of currently blocked signals
2509 * @how: whether to add, remove, or set signals
2510 * @nset: stores pending signals
2511 * @oset: previous value of signal mask if non-null
2512 * @sigsetsize: size of sigset_t type
2514 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2515 sigset_t __user *, oset, size_t, sigsetsize)
2517 sigset_t old_set, new_set;
2520 /* XXX: Don't preclude handling different sized sigset_t's. */
2521 if (sigsetsize != sizeof(sigset_t))
2524 old_set = current->blocked;
2527 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2529 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2531 error = sigprocmask(how, &new_set, NULL);
2537 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2544 long do_sigpending(void __user *set, unsigned long sigsetsize)
2546 long error = -EINVAL;
2549 if (sigsetsize > sizeof(sigset_t))
2552 spin_lock_irq(¤t->sighand->siglock);
2553 sigorsets(&pending, ¤t->pending.signal,
2554 ¤t->signal->shared_pending.signal);
2555 spin_unlock_irq(¤t->sighand->siglock);
2557 /* Outside the lock because only this thread touches it. */
2558 sigandsets(&pending, ¤t->blocked, &pending);
2561 if (!copy_to_user(set, &pending, sigsetsize))
2569 * sys_rt_sigpending - examine a pending signal that has been raised
2571 * @set: stores pending signals
2572 * @sigsetsize: size of sigset_t type or larger
2574 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2576 return do_sigpending(set, sigsetsize);
2579 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2581 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2585 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2587 if (from->si_code < 0)
2588 return __copy_to_user(to, from, sizeof(siginfo_t))
2591 * If you change siginfo_t structure, please be sure
2592 * this code is fixed accordingly.
2593 * Please remember to update the signalfd_copyinfo() function
2594 * inside fs/signalfd.c too, in case siginfo_t changes.
2595 * It should never copy any pad contained in the structure
2596 * to avoid security leaks, but must copy the generic
2597 * 3 ints plus the relevant union member.
2599 err = __put_user(from->si_signo, &to->si_signo);
2600 err |= __put_user(from->si_errno, &to->si_errno);
2601 err |= __put_user((short)from->si_code, &to->si_code);
2602 switch (from->si_code & __SI_MASK) {
2604 err |= __put_user(from->si_pid, &to->si_pid);
2605 err |= __put_user(from->si_uid, &to->si_uid);
2608 err |= __put_user(from->si_tid, &to->si_tid);
2609 err |= __put_user(from->si_overrun, &to->si_overrun);
2610 err |= __put_user(from->si_ptr, &to->si_ptr);
2613 err |= __put_user(from->si_band, &to->si_band);
2614 err |= __put_user(from->si_fd, &to->si_fd);
2617 err |= __put_user(from->si_addr, &to->si_addr);
2618 #ifdef __ARCH_SI_TRAPNO
2619 err |= __put_user(from->si_trapno, &to->si_trapno);
2621 #ifdef BUS_MCEERR_AO
2623 * Other callers might not initialize the si_lsb field,
2624 * so check explicitly for the right codes here.
2626 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2627 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2631 err |= __put_user(from->si_pid, &to->si_pid);
2632 err |= __put_user(from->si_uid, &to->si_uid);
2633 err |= __put_user(from->si_status, &to->si_status);
2634 err |= __put_user(from->si_utime, &to->si_utime);
2635 err |= __put_user(from->si_stime, &to->si_stime);
2637 case __SI_RT: /* This is not generated by the kernel as of now. */
2638 case __SI_MESGQ: /* But this is */
2639 err |= __put_user(from->si_pid, &to->si_pid);
2640 err |= __put_user(from->si_uid, &to->si_uid);
2641 err |= __put_user(from->si_ptr, &to->si_ptr);
2643 default: /* this is just in case for now ... */
2644 err |= __put_user(from->si_pid, &to->si_pid);
2645 err |= __put_user(from->si_uid, &to->si_uid);
2654 * do_sigtimedwait - wait for queued signals specified in @which
2655 * @which: queued signals to wait for
2656 * @info: if non-null, the signal's siginfo is returned here
2657 * @ts: upper bound on process time suspension
2659 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2660 const struct timespec *ts)
2662 struct task_struct *tsk = current;
2663 long timeout = MAX_SCHEDULE_TIMEOUT;
2664 sigset_t mask = *which;
2668 if (!timespec_valid(ts))
2670 timeout = timespec_to_jiffies(ts);
2672 * We can be close to the next tick, add another one
2673 * to ensure we will wait at least the time asked for.
2675 if (ts->tv_sec || ts->tv_nsec)
2680 * Invert the set of allowed signals to get those we want to block.
2682 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2685 spin_lock_irq(&tsk->sighand->siglock);
2686 sig = dequeue_signal(tsk, &mask, info);
2687 if (!sig && timeout) {
2689 * None ready, temporarily unblock those we're interested
2690 * while we are sleeping in so that we'll be awakened when
2691 * they arrive. Unblocking is always fine, we can avoid
2692 * set_current_blocked().
2694 tsk->real_blocked = tsk->blocked;
2695 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2696 recalc_sigpending();
2697 spin_unlock_irq(&tsk->sighand->siglock);
2699 timeout = schedule_timeout_interruptible(timeout);
2701 spin_lock_irq(&tsk->sighand->siglock);
2702 __set_task_blocked(tsk, &tsk->real_blocked);
2703 siginitset(&tsk->real_blocked, 0);
2704 sig = dequeue_signal(tsk, &mask, info);
2706 spin_unlock_irq(&tsk->sighand->siglock);
2710 return timeout ? -EINTR : -EAGAIN;
2714 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2716 * @uthese: queued signals to wait for
2717 * @uinfo: if non-null, the signal's siginfo is returned here
2718 * @uts: upper bound on process time suspension
2719 * @sigsetsize: size of sigset_t type
2721 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2722 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2730 /* XXX: Don't preclude handling different sized sigset_t's. */
2731 if (sigsetsize != sizeof(sigset_t))
2734 if (copy_from_user(&these, uthese, sizeof(these)))
2738 if (copy_from_user(&ts, uts, sizeof(ts)))
2742 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2744 if (ret > 0 && uinfo) {
2745 if (copy_siginfo_to_user(uinfo, &info))
2753 * sys_kill - send a signal to a process
2754 * @pid: the PID of the process
2755 * @sig: signal to be sent
2757 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2759 struct siginfo info;
2761 info.si_signo = sig;
2763 info.si_code = SI_USER;
2764 info.si_pid = task_tgid_vnr(current);
2765 info.si_uid = current_uid();
2767 return kill_something_info(sig, &info, pid);
2771 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2773 struct task_struct *p;
2777 p = find_task_by_vpid(pid);
2778 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2779 error = check_kill_permission(sig, info, p);
2781 * The null signal is a permissions and process existence
2782 * probe. No signal is actually delivered.
2784 if (!error && sig) {
2785 error = do_send_sig_info(sig, info, p, false);
2787 * If lock_task_sighand() failed we pretend the task
2788 * dies after receiving the signal. The window is tiny,
2789 * and the signal is private anyway.
2791 if (unlikely(error == -ESRCH))
2800 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2802 struct siginfo info = {};
2804 info.si_signo = sig;
2806 info.si_code = SI_TKILL;
2807 info.si_pid = task_tgid_vnr(current);
2808 info.si_uid = current_uid();
2810 return do_send_specific(tgid, pid, sig, &info);
2814 * sys_tgkill - send signal to one specific thread
2815 * @tgid: the thread group ID of the thread
2816 * @pid: the PID of the thread
2817 * @sig: signal to be sent
2819 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2820 * exists but it's not belonging to the target process anymore. This
2821 * method solves the problem of threads exiting and PIDs getting reused.
2823 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2825 /* This is only valid for single tasks */
2826 if (pid <= 0 || tgid <= 0)
2829 return do_tkill(tgid, pid, sig);
2833 * sys_tkill - send signal to one specific task
2834 * @pid: the PID of the task
2835 * @sig: signal to be sent
2837 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2839 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2841 /* This is only valid for single tasks */
2845 return do_tkill(0, pid, sig);
2849 * sys_rt_sigqueueinfo - send signal information to a signal
2850 * @pid: the PID of the thread
2851 * @sig: signal to be sent
2852 * @uinfo: signal info to be sent
2854 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2855 siginfo_t __user *, uinfo)
2859 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2862 /* Not even root can pretend to send signals from the kernel.
2863 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2865 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2866 /* We used to allow any < 0 si_code */
2867 WARN_ON_ONCE(info.si_code < 0);
2870 info.si_signo = sig;
2872 /* POSIX.1b doesn't mention process groups. */
2873 return kill_proc_info(sig, &info, pid);
2876 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2878 /* This is only valid for single tasks */
2879 if (pid <= 0 || tgid <= 0)
2882 /* Not even root can pretend to send signals from the kernel.
2883 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2885 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2886 /* We used to allow any < 0 si_code */
2887 WARN_ON_ONCE(info->si_code < 0);
2890 info->si_signo = sig;
2892 return do_send_specific(tgid, pid, sig, info);
2895 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2896 siginfo_t __user *, uinfo)
2900 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2903 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2906 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2908 struct task_struct *t = current;
2909 struct k_sigaction *k;
2912 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2915 k = &t->sighand->action[sig-1];
2917 spin_lock_irq(¤t->sighand->siglock);
2922 sigdelsetmask(&act->sa.sa_mask,
2923 sigmask(SIGKILL) | sigmask(SIGSTOP));
2927 * "Setting a signal action to SIG_IGN for a signal that is
2928 * pending shall cause the pending signal to be discarded,
2929 * whether or not it is blocked."
2931 * "Setting a signal action to SIG_DFL for a signal that is
2932 * pending and whose default action is to ignore the signal
2933 * (for example, SIGCHLD), shall cause the pending signal to
2934 * be discarded, whether or not it is blocked"
2936 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2938 sigaddset(&mask, sig);
2939 rm_from_queue_full(&mask, &t->signal->shared_pending);
2941 rm_from_queue_full(&mask, &t->pending);
2943 } while (t != current);
2947 spin_unlock_irq(¤t->sighand->siglock);
2952 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2957 oss.ss_sp = (void __user *) current->sas_ss_sp;
2958 oss.ss_size = current->sas_ss_size;
2959 oss.ss_flags = sas_ss_flags(sp);
2967 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
2969 error = __get_user(ss_sp, &uss->ss_sp) |
2970 __get_user(ss_flags, &uss->ss_flags) |
2971 __get_user(ss_size, &uss->ss_size);
2976 if (on_sig_stack(sp))
2981 * Note - this code used to test ss_flags incorrectly:
2982 * old code may have been written using ss_flags==0
2983 * to mean ss_flags==SS_ONSTACK (as this was the only
2984 * way that worked) - this fix preserves that older
2987 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2990 if (ss_flags == SS_DISABLE) {
2995 if (ss_size < MINSIGSTKSZ)
2999 current->sas_ss_sp = (unsigned long) ss_sp;
3000 current->sas_ss_size = ss_size;
3006 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3008 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3009 __put_user(oss.ss_size, &uoss->ss_size) |
3010 __put_user(oss.ss_flags, &uoss->ss_flags);
3017 #ifdef __ARCH_WANT_SYS_SIGPENDING
3020 * sys_sigpending - examine pending signals
3021 * @set: where mask of pending signal is returned
3023 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3025 return do_sigpending(set, sizeof(*set));
3030 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3032 * sys_sigprocmask - examine and change blocked signals
3033 * @how: whether to add, remove, or set signals
3034 * @nset: signals to add or remove (if non-null)
3035 * @oset: previous value of signal mask if non-null
3037 * Some platforms have their own version with special arguments;
3038 * others support only sys_rt_sigprocmask.
3041 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3042 old_sigset_t __user *, oset)
3044 old_sigset_t old_set, new_set;
3045 sigset_t new_blocked;
3047 old_set = current->blocked.sig[0];
3050 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3052 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3054 new_blocked = current->blocked;
3058 sigaddsetmask(&new_blocked, new_set);
3061 sigdelsetmask(&new_blocked, new_set);
3064 new_blocked.sig[0] = new_set;
3070 set_current_blocked(&new_blocked);
3074 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3080 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3082 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3084 * sys_rt_sigaction - alter an action taken by a process
3085 * @sig: signal to be sent
3086 * @act: new sigaction
3087 * @oact: used to save the previous sigaction
3088 * @sigsetsize: size of sigset_t type
3090 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3091 const struct sigaction __user *, act,
3092 struct sigaction __user *, oact,
3095 struct k_sigaction new_sa, old_sa;
3098 /* XXX: Don't preclude handling different sized sigset_t's. */
3099 if (sigsetsize != sizeof(sigset_t))
3103 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3107 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3110 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3116 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3118 #ifdef __ARCH_WANT_SYS_SGETMASK
3121 * For backwards compatibility. Functionality superseded by sigprocmask.
3123 SYSCALL_DEFINE0(sgetmask)
3126 return current->blocked.sig[0];
3129 SYSCALL_DEFINE1(ssetmask, int, newmask)
3131 int old = current->blocked.sig[0];
3134 siginitset(&newset, newmask & ~(sigmask(SIGKILL) | sigmask(SIGSTOP)));
3135 set_current_blocked(&newset);
3139 #endif /* __ARCH_WANT_SGETMASK */
3141 #ifdef __ARCH_WANT_SYS_SIGNAL
3143 * For backwards compatibility. Functionality superseded by sigaction.
3145 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3147 struct k_sigaction new_sa, old_sa;
3150 new_sa.sa.sa_handler = handler;
3151 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3152 sigemptyset(&new_sa.sa.sa_mask);
3154 ret = do_sigaction(sig, &new_sa, &old_sa);
3156 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3158 #endif /* __ARCH_WANT_SYS_SIGNAL */
3160 #ifdef __ARCH_WANT_SYS_PAUSE
3162 SYSCALL_DEFINE0(pause)
3164 while (!signal_pending(current)) {
3165 current->state = TASK_INTERRUPTIBLE;
3168 return -ERESTARTNOHAND;
3173 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3175 * sys_rt_sigsuspend - replace the signal mask for a value with the
3176 * @unewset value until a signal is received
3177 * @unewset: new signal mask value
3178 * @sigsetsize: size of sigset_t type
3180 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3184 /* XXX: Don't preclude handling different sized sigset_t's. */
3185 if (sigsetsize != sizeof(sigset_t))
3188 if (copy_from_user(&newset, unewset, sizeof(newset)))
3190 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
3192 current->saved_sigmask = current->blocked;
3193 set_current_blocked(&newset);
3195 current->state = TASK_INTERRUPTIBLE;
3197 set_restore_sigmask();
3198 return -ERESTARTNOHAND;
3200 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3202 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3207 void __init signals_init(void)
3209 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3212 #ifdef CONFIG_KGDB_KDB
3213 #include <linux/kdb.h>
3215 * kdb_send_sig_info - Allows kdb to send signals without exposing
3216 * signal internals. This function checks if the required locks are
3217 * available before calling the main signal code, to avoid kdb
3221 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3223 static struct task_struct *kdb_prev_t;
3225 if (!spin_trylock(&t->sighand->siglock)) {
3226 kdb_printf("Can't do kill command now.\n"
3227 "The sigmask lock is held somewhere else in "
3228 "kernel, try again later\n");
3231 spin_unlock(&t->sighand->siglock);
3232 new_t = kdb_prev_t != t;
3234 if (t->state != TASK_RUNNING && new_t) {
3235 kdb_printf("Process is not RUNNING, sending a signal from "
3236 "kdb risks deadlock\n"
3237 "on the run queue locks. "
3238 "The signal has _not_ been sent.\n"
3239 "Reissue the kill command if you want to risk "
3243 sig = info->si_signo;
3244 if (send_sig_info(sig, info, t))
3245 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3248 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3250 #endif /* CONFIG_KGDB_KDB */