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/mm.h>
17 #include <linux/sched/user.h>
18 #include <linux/sched/debug.h>
19 #include <linux/sched/task.h>
20 #include <linux/sched/task_stack.h>
21 #include <linux/sched/cputime.h>
23 #include <linux/tty.h>
24 #include <linux/binfmts.h>
25 #include <linux/coredump.h>
26 #include <linux/security.h>
27 #include <linux/syscalls.h>
28 #include <linux/ptrace.h>
29 #include <linux/signal.h>
30 #include <linux/signalfd.h>
31 #include <linux/ratelimit.h>
32 #include <linux/tracehook.h>
33 #include <linux/capability.h>
34 #include <linux/freezer.h>
35 #include <linux/pid_namespace.h>
36 #include <linux/nsproxy.h>
37 #include <linux/user_namespace.h>
38 #include <linux/uprobes.h>
39 #include <linux/compat.h>
40 #include <linux/cn_proc.h>
41 #include <linux/compiler.h>
42 #include <linux/posix-timers.h>
43 #include <linux/livepatch.h>
45 #define CREATE_TRACE_POINTS
46 #include <trace/events/signal.h>
48 #include <asm/param.h>
49 #include <linux/uaccess.h>
50 #include <asm/unistd.h>
51 #include <asm/siginfo.h>
52 #include <asm/cacheflush.h>
53 #include "audit.h" /* audit_signal_info() */
56 * SLAB caches for signal bits.
59 static struct kmem_cache *sigqueue_cachep;
61 int print_fatal_signals __read_mostly;
63 static void __user *sig_handler(struct task_struct *t, int sig)
65 return t->sighand->action[sig - 1].sa.sa_handler;
68 static int sig_handler_ignored(void __user *handler, int sig)
70 /* Is it explicitly or implicitly ignored? */
71 return handler == SIG_IGN ||
72 (handler == SIG_DFL && sig_kernel_ignore(sig));
75 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
79 handler = sig_handler(t, sig);
81 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
82 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
85 return sig_handler_ignored(handler, sig);
88 static int sig_ignored(struct task_struct *t, int sig, bool force)
91 * Blocked signals are never ignored, since the
92 * signal handler may change by the time it is
95 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
99 * Tracers may want to know about even ignored signal unless it
100 * is SIGKILL which can't be reported anyway but can be ignored
101 * by SIGNAL_UNKILLABLE task.
103 if (t->ptrace && sig != SIGKILL)
106 return sig_task_ignored(t, sig, force);
110 * Re-calculate pending state from the set of locally pending
111 * signals, globally pending signals, and blocked signals.
113 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
118 switch (_NSIG_WORDS) {
120 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
121 ready |= signal->sig[i] &~ blocked->sig[i];
124 case 4: ready = signal->sig[3] &~ blocked->sig[3];
125 ready |= signal->sig[2] &~ blocked->sig[2];
126 ready |= signal->sig[1] &~ blocked->sig[1];
127 ready |= signal->sig[0] &~ blocked->sig[0];
130 case 2: ready = signal->sig[1] &~ blocked->sig[1];
131 ready |= signal->sig[0] &~ blocked->sig[0];
134 case 1: ready = signal->sig[0] &~ blocked->sig[0];
139 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
141 static int recalc_sigpending_tsk(struct task_struct *t)
143 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
144 PENDING(&t->pending, &t->blocked) ||
145 PENDING(&t->signal->shared_pending, &t->blocked)) {
146 set_tsk_thread_flag(t, TIF_SIGPENDING);
150 * We must never clear the flag in another thread, or in current
151 * when it's possible the current syscall is returning -ERESTART*.
152 * So we don't clear it here, and only callers who know they should do.
158 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
159 * This is superfluous when called on current, the wakeup is a harmless no-op.
161 void recalc_sigpending_and_wake(struct task_struct *t)
163 if (recalc_sigpending_tsk(t))
164 signal_wake_up(t, 0);
167 void recalc_sigpending(void)
169 if (!recalc_sigpending_tsk(current) && !freezing(current) &&
170 !klp_patch_pending(current))
171 clear_thread_flag(TIF_SIGPENDING);
175 /* Given the mask, find the first available signal that should be serviced. */
177 #define SYNCHRONOUS_MASK \
178 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
179 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
181 int next_signal(struct sigpending *pending, sigset_t *mask)
183 unsigned long i, *s, *m, x;
186 s = pending->signal.sig;
190 * Handle the first word specially: it contains the
191 * synchronous signals that need to be dequeued first.
195 if (x & SYNCHRONOUS_MASK)
196 x &= SYNCHRONOUS_MASK;
201 switch (_NSIG_WORDS) {
203 for (i = 1; i < _NSIG_WORDS; ++i) {
207 sig = ffz(~x) + i*_NSIG_BPW + 1;
216 sig = ffz(~x) + _NSIG_BPW + 1;
227 static inline void print_dropped_signal(int sig)
229 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
231 if (!print_fatal_signals)
234 if (!__ratelimit(&ratelimit_state))
237 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
238 current->comm, current->pid, sig);
242 * task_set_jobctl_pending - set jobctl pending bits
244 * @mask: pending bits to set
246 * Clear @mask from @task->jobctl. @mask must be subset of
247 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
248 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
249 * cleared. If @task is already being killed or exiting, this function
253 * Must be called with @task->sighand->siglock held.
256 * %true if @mask is set, %false if made noop because @task was dying.
258 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
260 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
261 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
262 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
264 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
267 if (mask & JOBCTL_STOP_SIGMASK)
268 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
270 task->jobctl |= mask;
275 * task_clear_jobctl_trapping - clear jobctl trapping bit
278 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
279 * Clear it and wake up the ptracer. Note that we don't need any further
280 * locking. @task->siglock guarantees that @task->parent points to the
284 * Must be called with @task->sighand->siglock held.
286 void task_clear_jobctl_trapping(struct task_struct *task)
288 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
289 task->jobctl &= ~JOBCTL_TRAPPING;
290 smp_mb(); /* advised by wake_up_bit() */
291 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
296 * task_clear_jobctl_pending - clear jobctl pending bits
298 * @mask: pending bits to clear
300 * Clear @mask from @task->jobctl. @mask must be subset of
301 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
302 * STOP bits are cleared together.
304 * If clearing of @mask leaves no stop or trap pending, this function calls
305 * task_clear_jobctl_trapping().
308 * Must be called with @task->sighand->siglock held.
310 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
312 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
314 if (mask & JOBCTL_STOP_PENDING)
315 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
317 task->jobctl &= ~mask;
319 if (!(task->jobctl & JOBCTL_PENDING_MASK))
320 task_clear_jobctl_trapping(task);
324 * task_participate_group_stop - participate in a group stop
325 * @task: task participating in a group stop
327 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
328 * Group stop states are cleared and the group stop count is consumed if
329 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
330 * stop, the appropriate %SIGNAL_* flags are set.
333 * Must be called with @task->sighand->siglock held.
336 * %true if group stop completion should be notified to the parent, %false
339 static bool task_participate_group_stop(struct task_struct *task)
341 struct signal_struct *sig = task->signal;
342 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
344 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
346 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
351 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
352 sig->group_stop_count--;
355 * Tell the caller to notify completion iff we are entering into a
356 * fresh group stop. Read comment in do_signal_stop() for details.
358 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
359 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
366 * allocate a new signal queue record
367 * - this may be called without locks if and only if t == current, otherwise an
368 * appropriate lock must be held to stop the target task from exiting
370 static struct sigqueue *
371 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
373 struct sigqueue *q = NULL;
374 struct user_struct *user;
377 * Protect access to @t credentials. This can go away when all
378 * callers hold rcu read lock.
381 user = get_uid(__task_cred(t)->user);
382 atomic_inc(&user->sigpending);
385 if (override_rlimit ||
386 atomic_read(&user->sigpending) <=
387 task_rlimit(t, RLIMIT_SIGPENDING)) {
388 q = kmem_cache_alloc(sigqueue_cachep, flags);
390 print_dropped_signal(sig);
393 if (unlikely(q == NULL)) {
394 atomic_dec(&user->sigpending);
397 INIT_LIST_HEAD(&q->list);
405 static void __sigqueue_free(struct sigqueue *q)
407 if (q->flags & SIGQUEUE_PREALLOC)
409 atomic_dec(&q->user->sigpending);
411 kmem_cache_free(sigqueue_cachep, q);
414 void flush_sigqueue(struct sigpending *queue)
418 sigemptyset(&queue->signal);
419 while (!list_empty(&queue->list)) {
420 q = list_entry(queue->list.next, struct sigqueue , list);
421 list_del_init(&q->list);
427 * Flush all pending signals for this kthread.
429 void flush_signals(struct task_struct *t)
433 spin_lock_irqsave(&t->sighand->siglock, flags);
434 clear_tsk_thread_flag(t, TIF_SIGPENDING);
435 flush_sigqueue(&t->pending);
436 flush_sigqueue(&t->signal->shared_pending);
437 spin_unlock_irqrestore(&t->sighand->siglock, flags);
440 #ifdef CONFIG_POSIX_TIMERS
441 static void __flush_itimer_signals(struct sigpending *pending)
443 sigset_t signal, retain;
444 struct sigqueue *q, *n;
446 signal = pending->signal;
447 sigemptyset(&retain);
449 list_for_each_entry_safe(q, n, &pending->list, list) {
450 int sig = q->info.si_signo;
452 if (likely(q->info.si_code != SI_TIMER)) {
453 sigaddset(&retain, sig);
455 sigdelset(&signal, sig);
456 list_del_init(&q->list);
461 sigorsets(&pending->signal, &signal, &retain);
464 void flush_itimer_signals(void)
466 struct task_struct *tsk = current;
469 spin_lock_irqsave(&tsk->sighand->siglock, flags);
470 __flush_itimer_signals(&tsk->pending);
471 __flush_itimer_signals(&tsk->signal->shared_pending);
472 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
476 void ignore_signals(struct task_struct *t)
480 for (i = 0; i < _NSIG; ++i)
481 t->sighand->action[i].sa.sa_handler = SIG_IGN;
487 * Flush all handlers for a task.
491 flush_signal_handlers(struct task_struct *t, int force_default)
494 struct k_sigaction *ka = &t->sighand->action[0];
495 for (i = _NSIG ; i != 0 ; i--) {
496 if (force_default || ka->sa.sa_handler != SIG_IGN)
497 ka->sa.sa_handler = SIG_DFL;
499 #ifdef __ARCH_HAS_SA_RESTORER
500 ka->sa.sa_restorer = NULL;
502 sigemptyset(&ka->sa.sa_mask);
507 int unhandled_signal(struct task_struct *tsk, int sig)
509 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
510 if (is_global_init(tsk))
512 if (handler != SIG_IGN && handler != SIG_DFL)
514 /* if ptraced, let the tracer determine */
518 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
521 struct sigqueue *q, *first = NULL;
524 * Collect the siginfo appropriate to this signal. Check if
525 * there is another siginfo for the same signal.
527 list_for_each_entry(q, &list->list, list) {
528 if (q->info.si_signo == sig) {
535 sigdelset(&list->signal, sig);
539 list_del_init(&first->list);
540 copy_siginfo(info, &first->info);
543 (first->flags & SIGQUEUE_PREALLOC) &&
544 (info->si_code == SI_TIMER) &&
545 (info->si_sys_private);
547 __sigqueue_free(first);
550 * Ok, it wasn't in the queue. This must be
551 * a fast-pathed signal or we must have been
552 * out of queue space. So zero out the info.
555 info->si_signo = sig;
557 info->si_code = SI_USER;
563 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
564 siginfo_t *info, bool *resched_timer)
566 int sig = next_signal(pending, mask);
569 collect_signal(sig, pending, info, resched_timer);
574 * Dequeue a signal and return the element to the caller, which is
575 * expected to free it.
577 * All callers have to hold the siglock.
579 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
581 bool resched_timer = false;
584 /* We only dequeue private signals from ourselves, we don't let
585 * signalfd steal them
587 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
589 signr = __dequeue_signal(&tsk->signal->shared_pending,
590 mask, info, &resched_timer);
591 #ifdef CONFIG_POSIX_TIMERS
595 * itimers are process shared and we restart periodic
596 * itimers in the signal delivery path to prevent DoS
597 * attacks in the high resolution timer case. This is
598 * compliant with the old way of self-restarting
599 * itimers, as the SIGALRM is a legacy signal and only
600 * queued once. Changing the restart behaviour to
601 * restart the timer in the signal dequeue path is
602 * reducing the timer noise on heavy loaded !highres
605 if (unlikely(signr == SIGALRM)) {
606 struct hrtimer *tmr = &tsk->signal->real_timer;
608 if (!hrtimer_is_queued(tmr) &&
609 tsk->signal->it_real_incr != 0) {
610 hrtimer_forward(tmr, tmr->base->get_time(),
611 tsk->signal->it_real_incr);
612 hrtimer_restart(tmr);
622 if (unlikely(sig_kernel_stop(signr))) {
624 * Set a marker that we have dequeued a stop signal. Our
625 * caller might release the siglock and then the pending
626 * stop signal it is about to process is no longer in the
627 * pending bitmasks, but must still be cleared by a SIGCONT
628 * (and overruled by a SIGKILL). So those cases clear this
629 * shared flag after we've set it. Note that this flag may
630 * remain set after the signal we return is ignored or
631 * handled. That doesn't matter because its only purpose
632 * is to alert stop-signal processing code when another
633 * processor has come along and cleared the flag.
635 current->jobctl |= JOBCTL_STOP_DEQUEUED;
637 #ifdef CONFIG_POSIX_TIMERS
640 * Release the siglock to ensure proper locking order
641 * of timer locks outside of siglocks. Note, we leave
642 * irqs disabled here, since the posix-timers code is
643 * about to disable them again anyway.
645 spin_unlock(&tsk->sighand->siglock);
646 posixtimer_rearm(info);
647 spin_lock(&tsk->sighand->siglock);
649 /* Don't expose the si_sys_private value to userspace */
650 info->si_sys_private = 0;
657 * Tell a process that it has a new active signal..
659 * NOTE! we rely on the previous spin_lock to
660 * lock interrupts for us! We can only be called with
661 * "siglock" held, and the local interrupt must
662 * have been disabled when that got acquired!
664 * No need to set need_resched since signal event passing
665 * goes through ->blocked
667 void signal_wake_up_state(struct task_struct *t, unsigned int state)
669 set_tsk_thread_flag(t, TIF_SIGPENDING);
671 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
672 * case. We don't check t->state here because there is a race with it
673 * executing another processor and just now entering stopped state.
674 * By using wake_up_state, we ensure the process will wake up and
675 * handle its death signal.
677 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
682 * Remove signals in mask from the pending set and queue.
683 * Returns 1 if any signals were found.
685 * All callers must be holding the siglock.
687 static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
689 struct sigqueue *q, *n;
692 sigandsets(&m, mask, &s->signal);
693 if (sigisemptyset(&m))
696 sigandnsets(&s->signal, &s->signal, mask);
697 list_for_each_entry_safe(q, n, &s->list, list) {
698 if (sigismember(mask, q->info.si_signo)) {
699 list_del_init(&q->list);
706 static inline int is_si_special(const struct siginfo *info)
708 return info <= SEND_SIG_FORCED;
711 static inline bool si_fromuser(const struct siginfo *info)
713 return info == SEND_SIG_NOINFO ||
714 (!is_si_special(info) && SI_FROMUSER(info));
718 * called with RCU read lock from check_kill_permission()
720 static int kill_ok_by_cred(struct task_struct *t)
722 const struct cred *cred = current_cred();
723 const struct cred *tcred = __task_cred(t);
725 if (uid_eq(cred->euid, tcred->suid) ||
726 uid_eq(cred->euid, tcred->uid) ||
727 uid_eq(cred->uid, tcred->suid) ||
728 uid_eq(cred->uid, tcred->uid))
731 if (ns_capable(tcred->user_ns, CAP_KILL))
738 * Bad permissions for sending the signal
739 * - the caller must hold the RCU read lock
741 static int check_kill_permission(int sig, struct siginfo *info,
742 struct task_struct *t)
747 if (!valid_signal(sig))
750 if (!si_fromuser(info))
753 error = audit_signal_info(sig, t); /* Let audit system see the signal */
757 if (!same_thread_group(current, t) &&
758 !kill_ok_by_cred(t)) {
761 sid = task_session(t);
763 * We don't return the error if sid == NULL. The
764 * task was unhashed, the caller must notice this.
766 if (!sid || sid == task_session(current))
773 return security_task_kill(t, info, sig, NULL);
777 * ptrace_trap_notify - schedule trap to notify ptracer
778 * @t: tracee wanting to notify tracer
780 * This function schedules sticky ptrace trap which is cleared on the next
781 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
784 * If @t is running, STOP trap will be taken. If trapped for STOP and
785 * ptracer is listening for events, tracee is woken up so that it can
786 * re-trap for the new event. If trapped otherwise, STOP trap will be
787 * eventually taken without returning to userland after the existing traps
788 * are finished by PTRACE_CONT.
791 * Must be called with @task->sighand->siglock held.
793 static void ptrace_trap_notify(struct task_struct *t)
795 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
796 assert_spin_locked(&t->sighand->siglock);
798 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
799 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
803 * Handle magic process-wide effects of stop/continue signals. Unlike
804 * the signal actions, these happen immediately at signal-generation
805 * time regardless of blocking, ignoring, or handling. This does the
806 * actual continuing for SIGCONT, but not the actual stopping for stop
807 * signals. The process stop is done as a signal action for SIG_DFL.
809 * Returns true if the signal should be actually delivered, otherwise
810 * it should be dropped.
812 static bool prepare_signal(int sig, struct task_struct *p, bool force)
814 struct signal_struct *signal = p->signal;
815 struct task_struct *t;
818 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
819 if (!(signal->flags & SIGNAL_GROUP_EXIT))
820 return sig == SIGKILL;
822 * The process is in the middle of dying, nothing to do.
824 } else if (sig_kernel_stop(sig)) {
826 * This is a stop signal. Remove SIGCONT from all queues.
828 siginitset(&flush, sigmask(SIGCONT));
829 flush_sigqueue_mask(&flush, &signal->shared_pending);
830 for_each_thread(p, t)
831 flush_sigqueue_mask(&flush, &t->pending);
832 } else if (sig == SIGCONT) {
835 * Remove all stop signals from all queues, wake all threads.
837 siginitset(&flush, SIG_KERNEL_STOP_MASK);
838 flush_sigqueue_mask(&flush, &signal->shared_pending);
839 for_each_thread(p, t) {
840 flush_sigqueue_mask(&flush, &t->pending);
841 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
842 if (likely(!(t->ptrace & PT_SEIZED)))
843 wake_up_state(t, __TASK_STOPPED);
845 ptrace_trap_notify(t);
849 * Notify the parent with CLD_CONTINUED if we were stopped.
851 * If we were in the middle of a group stop, we pretend it
852 * was already finished, and then continued. Since SIGCHLD
853 * doesn't queue we report only CLD_STOPPED, as if the next
854 * CLD_CONTINUED was dropped.
857 if (signal->flags & SIGNAL_STOP_STOPPED)
858 why |= SIGNAL_CLD_CONTINUED;
859 else if (signal->group_stop_count)
860 why |= SIGNAL_CLD_STOPPED;
864 * The first thread which returns from do_signal_stop()
865 * will take ->siglock, notice SIGNAL_CLD_MASK, and
866 * notify its parent. See get_signal_to_deliver().
868 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
869 signal->group_stop_count = 0;
870 signal->group_exit_code = 0;
874 return !sig_ignored(p, sig, force);
878 * Test if P wants to take SIG. After we've checked all threads with this,
879 * it's equivalent to finding no threads not blocking SIG. Any threads not
880 * blocking SIG were ruled out because they are not running and already
881 * have pending signals. Such threads will dequeue from the shared queue
882 * as soon as they're available, so putting the signal on the shared queue
883 * will be equivalent to sending it to one such thread.
885 static inline int wants_signal(int sig, struct task_struct *p)
887 if (sigismember(&p->blocked, sig))
889 if (p->flags & PF_EXITING)
893 if (task_is_stopped_or_traced(p))
895 return task_curr(p) || !signal_pending(p);
898 static void complete_signal(int sig, struct task_struct *p, int group)
900 struct signal_struct *signal = p->signal;
901 struct task_struct *t;
904 * Now find a thread we can wake up to take the signal off the queue.
906 * If the main thread wants the signal, it gets first crack.
907 * Probably the least surprising to the average bear.
909 if (wants_signal(sig, p))
911 else if (!group || thread_group_empty(p))
913 * There is just one thread and it does not need to be woken.
914 * It will dequeue unblocked signals before it runs again.
919 * Otherwise try to find a suitable thread.
921 t = signal->curr_target;
922 while (!wants_signal(sig, t)) {
924 if (t == signal->curr_target)
926 * No thread needs to be woken.
927 * Any eligible threads will see
928 * the signal in the queue soon.
932 signal->curr_target = t;
936 * Found a killable thread. If the signal will be fatal,
937 * then start taking the whole group down immediately.
939 if (sig_fatal(p, sig) &&
940 !(signal->flags & SIGNAL_GROUP_EXIT) &&
941 !sigismember(&t->real_blocked, sig) &&
942 (sig == SIGKILL || !p->ptrace)) {
944 * This signal will be fatal to the whole group.
946 if (!sig_kernel_coredump(sig)) {
948 * Start a group exit and wake everybody up.
949 * This way we don't have other threads
950 * running and doing things after a slower
951 * thread has the fatal signal pending.
953 signal->flags = SIGNAL_GROUP_EXIT;
954 signal->group_exit_code = sig;
955 signal->group_stop_count = 0;
958 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
959 sigaddset(&t->pending.signal, SIGKILL);
960 signal_wake_up(t, 1);
961 } while_each_thread(p, t);
967 * The signal is already in the shared-pending queue.
968 * Tell the chosen thread to wake up and dequeue it.
970 signal_wake_up(t, sig == SIGKILL);
974 static inline int legacy_queue(struct sigpending *signals, int sig)
976 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
979 #ifdef CONFIG_USER_NS
980 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
982 if (current_user_ns() == task_cred_xxx(t, user_ns))
985 if (SI_FROMKERNEL(info))
989 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
990 make_kuid(current_user_ns(), info->si_uid));
994 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1000 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1001 int group, int from_ancestor_ns)
1003 struct sigpending *pending;
1005 int override_rlimit;
1006 int ret = 0, result;
1008 assert_spin_locked(&t->sighand->siglock);
1010 result = TRACE_SIGNAL_IGNORED;
1011 if (!prepare_signal(sig, t,
1012 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1015 pending = group ? &t->signal->shared_pending : &t->pending;
1017 * Short-circuit ignored signals and support queuing
1018 * exactly one non-rt signal, so that we can get more
1019 * detailed information about the cause of the signal.
1021 result = TRACE_SIGNAL_ALREADY_PENDING;
1022 if (legacy_queue(pending, sig))
1025 result = TRACE_SIGNAL_DELIVERED;
1027 * fast-pathed signals for kernel-internal things like SIGSTOP
1030 if (info == SEND_SIG_FORCED)
1034 * Real-time signals must be queued if sent by sigqueue, or
1035 * some other real-time mechanism. It is implementation
1036 * defined whether kill() does so. We attempt to do so, on
1037 * the principle of least surprise, but since kill is not
1038 * allowed to fail with EAGAIN when low on memory we just
1039 * make sure at least one signal gets delivered and don't
1040 * pass on the info struct.
1043 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1045 override_rlimit = 0;
1047 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1049 list_add_tail(&q->list, &pending->list);
1050 switch ((unsigned long) info) {
1051 case (unsigned long) SEND_SIG_NOINFO:
1052 clear_siginfo(&q->info);
1053 q->info.si_signo = sig;
1054 q->info.si_errno = 0;
1055 q->info.si_code = SI_USER;
1056 q->info.si_pid = task_tgid_nr_ns(current,
1057 task_active_pid_ns(t));
1058 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1060 case (unsigned long) SEND_SIG_PRIV:
1061 clear_siginfo(&q->info);
1062 q->info.si_signo = sig;
1063 q->info.si_errno = 0;
1064 q->info.si_code = SI_KERNEL;
1069 copy_siginfo(&q->info, info);
1070 if (from_ancestor_ns)
1075 userns_fixup_signal_uid(&q->info, t);
1077 } else if (!is_si_special(info)) {
1078 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1080 * Queue overflow, abort. We may abort if the
1081 * signal was rt and sent by user using something
1082 * other than kill().
1084 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1089 * This is a silent loss of information. We still
1090 * send the signal, but the *info bits are lost.
1092 result = TRACE_SIGNAL_LOSE_INFO;
1097 signalfd_notify(t, sig);
1098 sigaddset(&pending->signal, sig);
1099 complete_signal(sig, t, group);
1101 trace_signal_generate(sig, info, t, group, result);
1105 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1108 int from_ancestor_ns = 0;
1110 #ifdef CONFIG_PID_NS
1111 from_ancestor_ns = si_fromuser(info) &&
1112 !task_pid_nr_ns(current, task_active_pid_ns(t));
1115 return __send_signal(sig, info, t, group, from_ancestor_ns);
1118 static void print_fatal_signal(int signr)
1120 struct pt_regs *regs = signal_pt_regs();
1121 pr_info("potentially unexpected fatal signal %d.\n", signr);
1123 #if defined(__i386__) && !defined(__arch_um__)
1124 pr_info("code at %08lx: ", regs->ip);
1127 for (i = 0; i < 16; i++) {
1130 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1132 pr_cont("%02x ", insn);
1142 static int __init setup_print_fatal_signals(char *str)
1144 get_option (&str, &print_fatal_signals);
1149 __setup("print-fatal-signals=", setup_print_fatal_signals);
1152 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1154 return send_signal(sig, info, p, 1);
1158 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1160 return send_signal(sig, info, t, 0);
1163 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1166 unsigned long flags;
1169 if (lock_task_sighand(p, &flags)) {
1170 ret = send_signal(sig, info, p, group);
1171 unlock_task_sighand(p, &flags);
1178 * Force a signal that the process can't ignore: if necessary
1179 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1181 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1182 * since we do not want to have a signal handler that was blocked
1183 * be invoked when user space had explicitly blocked it.
1185 * We don't want to have recursive SIGSEGV's etc, for example,
1186 * that is why we also clear SIGNAL_UNKILLABLE.
1189 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1191 unsigned long int flags;
1192 int ret, blocked, ignored;
1193 struct k_sigaction *action;
1195 spin_lock_irqsave(&t->sighand->siglock, flags);
1196 action = &t->sighand->action[sig-1];
1197 ignored = action->sa.sa_handler == SIG_IGN;
1198 blocked = sigismember(&t->blocked, sig);
1199 if (blocked || ignored) {
1200 action->sa.sa_handler = SIG_DFL;
1202 sigdelset(&t->blocked, sig);
1203 recalc_sigpending_and_wake(t);
1207 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1208 * debugging to leave init killable.
1210 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1211 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1212 ret = specific_send_sig_info(sig, info, t);
1213 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1219 * Nuke all other threads in the group.
1221 int zap_other_threads(struct task_struct *p)
1223 struct task_struct *t = p;
1226 p->signal->group_stop_count = 0;
1228 while_each_thread(p, t) {
1229 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1232 /* Don't bother with already dead threads */
1235 sigaddset(&t->pending.signal, SIGKILL);
1236 signal_wake_up(t, 1);
1242 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1243 unsigned long *flags)
1245 struct sighand_struct *sighand;
1249 sighand = rcu_dereference(tsk->sighand);
1250 if (unlikely(sighand == NULL))
1254 * This sighand can be already freed and even reused, but
1255 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1256 * initializes ->siglock: this slab can't go away, it has
1257 * the same object type, ->siglock can't be reinitialized.
1259 * We need to ensure that tsk->sighand is still the same
1260 * after we take the lock, we can race with de_thread() or
1261 * __exit_signal(). In the latter case the next iteration
1262 * must see ->sighand == NULL.
1264 spin_lock_irqsave(&sighand->siglock, *flags);
1265 if (likely(sighand == tsk->sighand))
1267 spin_unlock_irqrestore(&sighand->siglock, *flags);
1275 * send signal info to all the members of a group
1277 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1282 ret = check_kill_permission(sig, info, p);
1286 ret = do_send_sig_info(sig, info, p, true);
1292 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1293 * control characters do (^C, ^Z etc)
1294 * - the caller must hold at least a readlock on tasklist_lock
1296 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1298 struct task_struct *p = NULL;
1299 int retval, success;
1303 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1304 int err = group_send_sig_info(sig, info, p);
1307 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1308 return success ? 0 : retval;
1311 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1314 struct task_struct *p;
1318 p = pid_task(pid, PIDTYPE_PID);
1320 error = group_send_sig_info(sig, info, p);
1322 if (likely(!p || error != -ESRCH))
1326 * The task was unhashed in between, try again. If it
1327 * is dead, pid_task() will return NULL, if we race with
1328 * de_thread() it will find the new leader.
1333 static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1337 error = kill_pid_info(sig, info, find_vpid(pid));
1342 static int kill_as_cred_perm(const struct cred *cred,
1343 struct task_struct *target)
1345 const struct cred *pcred = __task_cred(target);
1346 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1347 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1352 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1353 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1354 const struct cred *cred)
1357 struct task_struct *p;
1358 unsigned long flags;
1360 if (!valid_signal(sig))
1364 p = pid_task(pid, PIDTYPE_PID);
1369 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1373 ret = security_task_kill(p, info, sig, cred);
1378 if (lock_task_sighand(p, &flags)) {
1379 ret = __send_signal(sig, info, p, 1, 0);
1380 unlock_task_sighand(p, &flags);
1388 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1391 * kill_something_info() interprets pid in interesting ways just like kill(2).
1393 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1394 * is probably wrong. Should make it like BSD or SYSV.
1397 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1403 ret = kill_pid_info(sig, info, find_vpid(pid));
1408 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1412 read_lock(&tasklist_lock);
1414 ret = __kill_pgrp_info(sig, info,
1415 pid ? find_vpid(-pid) : task_pgrp(current));
1417 int retval = 0, count = 0;
1418 struct task_struct * p;
1420 for_each_process(p) {
1421 if (task_pid_vnr(p) > 1 &&
1422 !same_thread_group(p, current)) {
1423 int err = group_send_sig_info(sig, info, p);
1429 ret = count ? retval : -ESRCH;
1431 read_unlock(&tasklist_lock);
1437 * These are for backward compatibility with the rest of the kernel source.
1440 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1443 * Make sure legacy kernel users don't send in bad values
1444 * (normal paths check this in check_kill_permission).
1446 if (!valid_signal(sig))
1449 return do_send_sig_info(sig, info, p, false);
1452 #define __si_special(priv) \
1453 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1456 send_sig(int sig, struct task_struct *p, int priv)
1458 return send_sig_info(sig, __si_special(priv), p);
1461 void force_sig(int sig, struct task_struct *p)
1463 force_sig_info(sig, SEND_SIG_PRIV, p);
1467 * When things go south during signal handling, we
1468 * will force a SIGSEGV. And if the signal that caused
1469 * the problem was already a SIGSEGV, we'll want to
1470 * make sure we don't even try to deliver the signal..
1472 void force_sigsegv(int sig, struct task_struct *p)
1474 if (sig == SIGSEGV) {
1475 unsigned long flags;
1476 spin_lock_irqsave(&p->sighand->siglock, flags);
1477 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1478 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1480 force_sig(SIGSEGV, p);
1483 int force_sig_fault(int sig, int code, void __user *addr
1484 ___ARCH_SI_TRAPNO(int trapno)
1485 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1486 , struct task_struct *t)
1488 struct siginfo info;
1490 clear_siginfo(&info);
1491 info.si_signo = sig;
1493 info.si_code = code;
1494 info.si_addr = addr;
1495 #ifdef __ARCH_SI_TRAPNO
1496 info.si_trapno = trapno;
1500 info.si_flags = flags;
1503 return force_sig_info(info.si_signo, &info, t);
1506 int send_sig_fault(int sig, int code, void __user *addr
1507 ___ARCH_SI_TRAPNO(int trapno)
1508 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1509 , struct task_struct *t)
1511 struct siginfo info;
1513 clear_siginfo(&info);
1514 info.si_signo = sig;
1516 info.si_code = code;
1517 info.si_addr = addr;
1518 #ifdef __ARCH_SI_TRAPNO
1519 info.si_trapno = trapno;
1523 info.si_flags = flags;
1526 return send_sig_info(info.si_signo, &info, t);
1529 int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1531 struct siginfo info;
1533 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1534 clear_siginfo(&info);
1535 info.si_signo = SIGBUS;
1537 info.si_code = code;
1538 info.si_addr = addr;
1539 info.si_addr_lsb = lsb;
1540 return force_sig_info(info.si_signo, &info, t);
1543 int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1545 struct siginfo info;
1547 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1548 clear_siginfo(&info);
1549 info.si_signo = SIGBUS;
1551 info.si_code = code;
1552 info.si_addr = addr;
1553 info.si_addr_lsb = lsb;
1554 return send_sig_info(info.si_signo, &info, t);
1556 EXPORT_SYMBOL(send_sig_mceerr);
1558 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1560 struct siginfo info;
1562 clear_siginfo(&info);
1563 info.si_signo = SIGSEGV;
1565 info.si_code = SEGV_BNDERR;
1566 info.si_addr = addr;
1567 info.si_lower = lower;
1568 info.si_upper = upper;
1569 return force_sig_info(info.si_signo, &info, current);
1573 int force_sig_pkuerr(void __user *addr, u32 pkey)
1575 struct siginfo info;
1577 clear_siginfo(&info);
1578 info.si_signo = SIGSEGV;
1580 info.si_code = SEGV_PKUERR;
1581 info.si_addr = addr;
1582 info.si_pkey = pkey;
1583 return force_sig_info(info.si_signo, &info, current);
1587 /* For the crazy architectures that include trap information in
1588 * the errno field, instead of an actual errno value.
1590 int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1592 struct siginfo info;
1594 clear_siginfo(&info);
1595 info.si_signo = SIGTRAP;
1596 info.si_errno = errno;
1597 info.si_code = TRAP_HWBKPT;
1598 info.si_addr = addr;
1599 return force_sig_info(info.si_signo, &info, current);
1602 int kill_pgrp(struct pid *pid, int sig, int priv)
1606 read_lock(&tasklist_lock);
1607 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1608 read_unlock(&tasklist_lock);
1612 EXPORT_SYMBOL(kill_pgrp);
1614 int kill_pid(struct pid *pid, int sig, int priv)
1616 return kill_pid_info(sig, __si_special(priv), pid);
1618 EXPORT_SYMBOL(kill_pid);
1621 * These functions support sending signals using preallocated sigqueue
1622 * structures. This is needed "because realtime applications cannot
1623 * afford to lose notifications of asynchronous events, like timer
1624 * expirations or I/O completions". In the case of POSIX Timers
1625 * we allocate the sigqueue structure from the timer_create. If this
1626 * allocation fails we are able to report the failure to the application
1627 * with an EAGAIN error.
1629 struct sigqueue *sigqueue_alloc(void)
1631 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1634 q->flags |= SIGQUEUE_PREALLOC;
1639 void sigqueue_free(struct sigqueue *q)
1641 unsigned long flags;
1642 spinlock_t *lock = ¤t->sighand->siglock;
1644 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1646 * We must hold ->siglock while testing q->list
1647 * to serialize with collect_signal() or with
1648 * __exit_signal()->flush_sigqueue().
1650 spin_lock_irqsave(lock, flags);
1651 q->flags &= ~SIGQUEUE_PREALLOC;
1653 * If it is queued it will be freed when dequeued,
1654 * like the "regular" sigqueue.
1656 if (!list_empty(&q->list))
1658 spin_unlock_irqrestore(lock, flags);
1664 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1666 int sig = q->info.si_signo;
1667 struct sigpending *pending;
1668 unsigned long flags;
1671 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1674 if (!likely(lock_task_sighand(t, &flags)))
1677 ret = 1; /* the signal is ignored */
1678 result = TRACE_SIGNAL_IGNORED;
1679 if (!prepare_signal(sig, t, false))
1683 if (unlikely(!list_empty(&q->list))) {
1685 * If an SI_TIMER entry is already queue just increment
1686 * the overrun count.
1688 BUG_ON(q->info.si_code != SI_TIMER);
1689 q->info.si_overrun++;
1690 result = TRACE_SIGNAL_ALREADY_PENDING;
1693 q->info.si_overrun = 0;
1695 signalfd_notify(t, sig);
1696 pending = group ? &t->signal->shared_pending : &t->pending;
1697 list_add_tail(&q->list, &pending->list);
1698 sigaddset(&pending->signal, sig);
1699 complete_signal(sig, t, group);
1700 result = TRACE_SIGNAL_DELIVERED;
1702 trace_signal_generate(sig, &q->info, t, group, result);
1703 unlock_task_sighand(t, &flags);
1709 * Let a parent know about the death of a child.
1710 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1712 * Returns true if our parent ignored us and so we've switched to
1715 bool do_notify_parent(struct task_struct *tsk, int sig)
1717 struct siginfo info;
1718 unsigned long flags;
1719 struct sighand_struct *psig;
1720 bool autoreap = false;
1725 /* do_notify_parent_cldstop should have been called instead. */
1726 BUG_ON(task_is_stopped_or_traced(tsk));
1728 BUG_ON(!tsk->ptrace &&
1729 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1731 if (sig != SIGCHLD) {
1733 * This is only possible if parent == real_parent.
1734 * Check if it has changed security domain.
1736 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1740 clear_siginfo(&info);
1741 info.si_signo = sig;
1744 * We are under tasklist_lock here so our parent is tied to
1745 * us and cannot change.
1747 * task_active_pid_ns will always return the same pid namespace
1748 * until a task passes through release_task.
1750 * write_lock() currently calls preempt_disable() which is the
1751 * same as rcu_read_lock(), but according to Oleg, this is not
1752 * correct to rely on this
1755 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1756 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1760 task_cputime(tsk, &utime, &stime);
1761 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1762 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1764 info.si_status = tsk->exit_code & 0x7f;
1765 if (tsk->exit_code & 0x80)
1766 info.si_code = CLD_DUMPED;
1767 else if (tsk->exit_code & 0x7f)
1768 info.si_code = CLD_KILLED;
1770 info.si_code = CLD_EXITED;
1771 info.si_status = tsk->exit_code >> 8;
1774 psig = tsk->parent->sighand;
1775 spin_lock_irqsave(&psig->siglock, flags);
1776 if (!tsk->ptrace && sig == SIGCHLD &&
1777 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1778 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1780 * We are exiting and our parent doesn't care. POSIX.1
1781 * defines special semantics for setting SIGCHLD to SIG_IGN
1782 * or setting the SA_NOCLDWAIT flag: we should be reaped
1783 * automatically and not left for our parent's wait4 call.
1784 * Rather than having the parent do it as a magic kind of
1785 * signal handler, we just set this to tell do_exit that we
1786 * can be cleaned up without becoming a zombie. Note that
1787 * we still call __wake_up_parent in this case, because a
1788 * blocked sys_wait4 might now return -ECHILD.
1790 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1791 * is implementation-defined: we do (if you don't want
1792 * it, just use SIG_IGN instead).
1795 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1798 if (valid_signal(sig) && sig)
1799 __group_send_sig_info(sig, &info, tsk->parent);
1800 __wake_up_parent(tsk, tsk->parent);
1801 spin_unlock_irqrestore(&psig->siglock, flags);
1807 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1808 * @tsk: task reporting the state change
1809 * @for_ptracer: the notification is for ptracer
1810 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1812 * Notify @tsk's parent that the stopped/continued state has changed. If
1813 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1814 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1817 * Must be called with tasklist_lock at least read locked.
1819 static void do_notify_parent_cldstop(struct task_struct *tsk,
1820 bool for_ptracer, int why)
1822 struct siginfo info;
1823 unsigned long flags;
1824 struct task_struct *parent;
1825 struct sighand_struct *sighand;
1829 parent = tsk->parent;
1831 tsk = tsk->group_leader;
1832 parent = tsk->real_parent;
1835 clear_siginfo(&info);
1836 info.si_signo = SIGCHLD;
1839 * see comment in do_notify_parent() about the following 4 lines
1842 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1843 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1846 task_cputime(tsk, &utime, &stime);
1847 info.si_utime = nsec_to_clock_t(utime);
1848 info.si_stime = nsec_to_clock_t(stime);
1853 info.si_status = SIGCONT;
1856 info.si_status = tsk->signal->group_exit_code & 0x7f;
1859 info.si_status = tsk->exit_code & 0x7f;
1865 sighand = parent->sighand;
1866 spin_lock_irqsave(&sighand->siglock, flags);
1867 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1868 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1869 __group_send_sig_info(SIGCHLD, &info, parent);
1871 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1873 __wake_up_parent(tsk, parent);
1874 spin_unlock_irqrestore(&sighand->siglock, flags);
1877 static inline int may_ptrace_stop(void)
1879 if (!likely(current->ptrace))
1882 * Are we in the middle of do_coredump?
1883 * If so and our tracer is also part of the coredump stopping
1884 * is a deadlock situation, and pointless because our tracer
1885 * is dead so don't allow us to stop.
1886 * If SIGKILL was already sent before the caller unlocked
1887 * ->siglock we must see ->core_state != NULL. Otherwise it
1888 * is safe to enter schedule().
1890 * This is almost outdated, a task with the pending SIGKILL can't
1891 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1892 * after SIGKILL was already dequeued.
1894 if (unlikely(current->mm->core_state) &&
1895 unlikely(current->mm == current->parent->mm))
1902 * Return non-zero if there is a SIGKILL that should be waking us up.
1903 * Called with the siglock held.
1905 static int sigkill_pending(struct task_struct *tsk)
1907 return sigismember(&tsk->pending.signal, SIGKILL) ||
1908 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1912 * This must be called with current->sighand->siglock held.
1914 * This should be the path for all ptrace stops.
1915 * We always set current->last_siginfo while stopped here.
1916 * That makes it a way to test a stopped process for
1917 * being ptrace-stopped vs being job-control-stopped.
1919 * If we actually decide not to stop at all because the tracer
1920 * is gone, we keep current->exit_code unless clear_code.
1922 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1923 __releases(¤t->sighand->siglock)
1924 __acquires(¤t->sighand->siglock)
1926 bool gstop_done = false;
1928 if (arch_ptrace_stop_needed(exit_code, info)) {
1930 * The arch code has something special to do before a
1931 * ptrace stop. This is allowed to block, e.g. for faults
1932 * on user stack pages. We can't keep the siglock while
1933 * calling arch_ptrace_stop, so we must release it now.
1934 * To preserve proper semantics, we must do this before
1935 * any signal bookkeeping like checking group_stop_count.
1936 * Meanwhile, a SIGKILL could come in before we retake the
1937 * siglock. That must prevent us from sleeping in TASK_TRACED.
1938 * So after regaining the lock, we must check for SIGKILL.
1940 spin_unlock_irq(¤t->sighand->siglock);
1941 arch_ptrace_stop(exit_code, info);
1942 spin_lock_irq(¤t->sighand->siglock);
1943 if (sigkill_pending(current))
1947 set_special_state(TASK_TRACED);
1950 * We're committing to trapping. TRACED should be visible before
1951 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1952 * Also, transition to TRACED and updates to ->jobctl should be
1953 * atomic with respect to siglock and should be done after the arch
1954 * hook as siglock is released and regrabbed across it.
1959 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
1961 * set_current_state() smp_wmb();
1963 * wait_task_stopped()
1964 * task_stopped_code()
1965 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
1969 current->last_siginfo = info;
1970 current->exit_code = exit_code;
1973 * If @why is CLD_STOPPED, we're trapping to participate in a group
1974 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1975 * across siglock relocks since INTERRUPT was scheduled, PENDING
1976 * could be clear now. We act as if SIGCONT is received after
1977 * TASK_TRACED is entered - ignore it.
1979 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1980 gstop_done = task_participate_group_stop(current);
1982 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1983 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1984 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1985 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1987 /* entering a trap, clear TRAPPING */
1988 task_clear_jobctl_trapping(current);
1990 spin_unlock_irq(¤t->sighand->siglock);
1991 read_lock(&tasklist_lock);
1992 if (may_ptrace_stop()) {
1994 * Notify parents of the stop.
1996 * While ptraced, there are two parents - the ptracer and
1997 * the real_parent of the group_leader. The ptracer should
1998 * know about every stop while the real parent is only
1999 * interested in the completion of group stop. The states
2000 * for the two don't interact with each other. Notify
2001 * separately unless they're gonna be duplicates.
2003 do_notify_parent_cldstop(current, true, why);
2004 if (gstop_done && ptrace_reparented(current))
2005 do_notify_parent_cldstop(current, false, why);
2008 * Don't want to allow preemption here, because
2009 * sys_ptrace() needs this task to be inactive.
2011 * XXX: implement read_unlock_no_resched().
2014 read_unlock(&tasklist_lock);
2015 preempt_enable_no_resched();
2016 freezable_schedule();
2019 * By the time we got the lock, our tracer went away.
2020 * Don't drop the lock yet, another tracer may come.
2022 * If @gstop_done, the ptracer went away between group stop
2023 * completion and here. During detach, it would have set
2024 * JOBCTL_STOP_PENDING on us and we'll re-enter
2025 * TASK_STOPPED in do_signal_stop() on return, so notifying
2026 * the real parent of the group stop completion is enough.
2029 do_notify_parent_cldstop(current, false, why);
2031 /* tasklist protects us from ptrace_freeze_traced() */
2032 __set_current_state(TASK_RUNNING);
2034 current->exit_code = 0;
2035 read_unlock(&tasklist_lock);
2039 * We are back. Now reacquire the siglock before touching
2040 * last_siginfo, so that we are sure to have synchronized with
2041 * any signal-sending on another CPU that wants to examine it.
2043 spin_lock_irq(¤t->sighand->siglock);
2044 current->last_siginfo = NULL;
2046 /* LISTENING can be set only during STOP traps, clear it */
2047 current->jobctl &= ~JOBCTL_LISTENING;
2050 * Queued signals ignored us while we were stopped for tracing.
2051 * So check for any that we should take before resuming user mode.
2052 * This sets TIF_SIGPENDING, but never clears it.
2054 recalc_sigpending_tsk(current);
2057 static void ptrace_do_notify(int signr, int exit_code, int why)
2061 clear_siginfo(&info);
2062 info.si_signo = signr;
2063 info.si_code = exit_code;
2064 info.si_pid = task_pid_vnr(current);
2065 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2067 /* Let the debugger run. */
2068 ptrace_stop(exit_code, why, 1, &info);
2071 void ptrace_notify(int exit_code)
2073 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2074 if (unlikely(current->task_works))
2077 spin_lock_irq(¤t->sighand->siglock);
2078 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2079 spin_unlock_irq(¤t->sighand->siglock);
2083 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2084 * @signr: signr causing group stop if initiating
2086 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2087 * and participate in it. If already set, participate in the existing
2088 * group stop. If participated in a group stop (and thus slept), %true is
2089 * returned with siglock released.
2091 * If ptraced, this function doesn't handle stop itself. Instead,
2092 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2093 * untouched. The caller must ensure that INTERRUPT trap handling takes
2094 * places afterwards.
2097 * Must be called with @current->sighand->siglock held, which is released
2101 * %false if group stop is already cancelled or ptrace trap is scheduled.
2102 * %true if participated in group stop.
2104 static bool do_signal_stop(int signr)
2105 __releases(¤t->sighand->siglock)
2107 struct signal_struct *sig = current->signal;
2109 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2110 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2111 struct task_struct *t;
2113 /* signr will be recorded in task->jobctl for retries */
2114 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2116 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2117 unlikely(signal_group_exit(sig)))
2120 * There is no group stop already in progress. We must
2123 * While ptraced, a task may be resumed while group stop is
2124 * still in effect and then receive a stop signal and
2125 * initiate another group stop. This deviates from the
2126 * usual behavior as two consecutive stop signals can't
2127 * cause two group stops when !ptraced. That is why we
2128 * also check !task_is_stopped(t) below.
2130 * The condition can be distinguished by testing whether
2131 * SIGNAL_STOP_STOPPED is already set. Don't generate
2132 * group_exit_code in such case.
2134 * This is not necessary for SIGNAL_STOP_CONTINUED because
2135 * an intervening stop signal is required to cause two
2136 * continued events regardless of ptrace.
2138 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2139 sig->group_exit_code = signr;
2141 sig->group_stop_count = 0;
2143 if (task_set_jobctl_pending(current, signr | gstop))
2144 sig->group_stop_count++;
2147 while_each_thread(current, t) {
2149 * Setting state to TASK_STOPPED for a group
2150 * stop is always done with the siglock held,
2151 * so this check has no races.
2153 if (!task_is_stopped(t) &&
2154 task_set_jobctl_pending(t, signr | gstop)) {
2155 sig->group_stop_count++;
2156 if (likely(!(t->ptrace & PT_SEIZED)))
2157 signal_wake_up(t, 0);
2159 ptrace_trap_notify(t);
2164 if (likely(!current->ptrace)) {
2168 * If there are no other threads in the group, or if there
2169 * is a group stop in progress and we are the last to stop,
2170 * report to the parent.
2172 if (task_participate_group_stop(current))
2173 notify = CLD_STOPPED;
2175 set_special_state(TASK_STOPPED);
2176 spin_unlock_irq(¤t->sighand->siglock);
2179 * Notify the parent of the group stop completion. Because
2180 * we're not holding either the siglock or tasklist_lock
2181 * here, ptracer may attach inbetween; however, this is for
2182 * group stop and should always be delivered to the real
2183 * parent of the group leader. The new ptracer will get
2184 * its notification when this task transitions into
2188 read_lock(&tasklist_lock);
2189 do_notify_parent_cldstop(current, false, notify);
2190 read_unlock(&tasklist_lock);
2193 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2194 freezable_schedule();
2198 * While ptraced, group stop is handled by STOP trap.
2199 * Schedule it and let the caller deal with it.
2201 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2207 * do_jobctl_trap - take care of ptrace jobctl traps
2209 * When PT_SEIZED, it's used for both group stop and explicit
2210 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2211 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2212 * the stop signal; otherwise, %SIGTRAP.
2214 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2215 * number as exit_code and no siginfo.
2218 * Must be called with @current->sighand->siglock held, which may be
2219 * released and re-acquired before returning with intervening sleep.
2221 static void do_jobctl_trap(void)
2223 struct signal_struct *signal = current->signal;
2224 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2226 if (current->ptrace & PT_SEIZED) {
2227 if (!signal->group_stop_count &&
2228 !(signal->flags & SIGNAL_STOP_STOPPED))
2230 WARN_ON_ONCE(!signr);
2231 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2234 WARN_ON_ONCE(!signr);
2235 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2236 current->exit_code = 0;
2240 static int ptrace_signal(int signr, siginfo_t *info)
2243 * We do not check sig_kernel_stop(signr) but set this marker
2244 * unconditionally because we do not know whether debugger will
2245 * change signr. This flag has no meaning unless we are going
2246 * to stop after return from ptrace_stop(). In this case it will
2247 * be checked in do_signal_stop(), we should only stop if it was
2248 * not cleared by SIGCONT while we were sleeping. See also the
2249 * comment in dequeue_signal().
2251 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2252 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2254 /* We're back. Did the debugger cancel the sig? */
2255 signr = current->exit_code;
2259 current->exit_code = 0;
2262 * Update the siginfo structure if the signal has
2263 * changed. If the debugger wanted something
2264 * specific in the siginfo structure then it should
2265 * have updated *info via PTRACE_SETSIGINFO.
2267 if (signr != info->si_signo) {
2268 clear_siginfo(info);
2269 info->si_signo = signr;
2271 info->si_code = SI_USER;
2273 info->si_pid = task_pid_vnr(current->parent);
2274 info->si_uid = from_kuid_munged(current_user_ns(),
2275 task_uid(current->parent));
2279 /* If the (new) signal is now blocked, requeue it. */
2280 if (sigismember(¤t->blocked, signr)) {
2281 specific_send_sig_info(signr, info, current);
2288 int get_signal(struct ksignal *ksig)
2290 struct sighand_struct *sighand = current->sighand;
2291 struct signal_struct *signal = current->signal;
2294 if (unlikely(current->task_works))
2297 if (unlikely(uprobe_deny_signal()))
2301 * Do this once, we can't return to user-mode if freezing() == T.
2302 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2303 * thus do not need another check after return.
2308 spin_lock_irq(&sighand->siglock);
2310 * Every stopped thread goes here after wakeup. Check to see if
2311 * we should notify the parent, prepare_signal(SIGCONT) encodes
2312 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2314 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2317 if (signal->flags & SIGNAL_CLD_CONTINUED)
2318 why = CLD_CONTINUED;
2322 signal->flags &= ~SIGNAL_CLD_MASK;
2324 spin_unlock_irq(&sighand->siglock);
2327 * Notify the parent that we're continuing. This event is
2328 * always per-process and doesn't make whole lot of sense
2329 * for ptracers, who shouldn't consume the state via
2330 * wait(2) either, but, for backward compatibility, notify
2331 * the ptracer of the group leader too unless it's gonna be
2334 read_lock(&tasklist_lock);
2335 do_notify_parent_cldstop(current, false, why);
2337 if (ptrace_reparented(current->group_leader))
2338 do_notify_parent_cldstop(current->group_leader,
2340 read_unlock(&tasklist_lock);
2346 struct k_sigaction *ka;
2348 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2352 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2354 spin_unlock_irq(&sighand->siglock);
2358 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2361 break; /* will return 0 */
2363 if (unlikely(current->ptrace) && signr != SIGKILL) {
2364 signr = ptrace_signal(signr, &ksig->info);
2369 ka = &sighand->action[signr-1];
2371 /* Trace actually delivered signals. */
2372 trace_signal_deliver(signr, &ksig->info, ka);
2374 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2376 if (ka->sa.sa_handler != SIG_DFL) {
2377 /* Run the handler. */
2380 if (ka->sa.sa_flags & SA_ONESHOT)
2381 ka->sa.sa_handler = SIG_DFL;
2383 break; /* will return non-zero "signr" value */
2387 * Now we are doing the default action for this signal.
2389 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2393 * Global init gets no signals it doesn't want.
2394 * Container-init gets no signals it doesn't want from same
2397 * Note that if global/container-init sees a sig_kernel_only()
2398 * signal here, the signal must have been generated internally
2399 * or must have come from an ancestor namespace. In either
2400 * case, the signal cannot be dropped.
2402 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2403 !sig_kernel_only(signr))
2406 if (sig_kernel_stop(signr)) {
2408 * The default action is to stop all threads in
2409 * the thread group. The job control signals
2410 * do nothing in an orphaned pgrp, but SIGSTOP
2411 * always works. Note that siglock needs to be
2412 * dropped during the call to is_orphaned_pgrp()
2413 * because of lock ordering with tasklist_lock.
2414 * This allows an intervening SIGCONT to be posted.
2415 * We need to check for that and bail out if necessary.
2417 if (signr != SIGSTOP) {
2418 spin_unlock_irq(&sighand->siglock);
2420 /* signals can be posted during this window */
2422 if (is_current_pgrp_orphaned())
2425 spin_lock_irq(&sighand->siglock);
2428 if (likely(do_signal_stop(ksig->info.si_signo))) {
2429 /* It released the siglock. */
2434 * We didn't actually stop, due to a race
2435 * with SIGCONT or something like that.
2440 spin_unlock_irq(&sighand->siglock);
2443 * Anything else is fatal, maybe with a core dump.
2445 current->flags |= PF_SIGNALED;
2447 if (sig_kernel_coredump(signr)) {
2448 if (print_fatal_signals)
2449 print_fatal_signal(ksig->info.si_signo);
2450 proc_coredump_connector(current);
2452 * If it was able to dump core, this kills all
2453 * other threads in the group and synchronizes with
2454 * their demise. If we lost the race with another
2455 * thread getting here, it set group_exit_code
2456 * first and our do_group_exit call below will use
2457 * that value and ignore the one we pass it.
2459 do_coredump(&ksig->info);
2463 * Death signals, no core dump.
2465 do_group_exit(ksig->info.si_signo);
2468 spin_unlock_irq(&sighand->siglock);
2471 return ksig->sig > 0;
2475 * signal_delivered -
2476 * @ksig: kernel signal struct
2477 * @stepping: nonzero if debugger single-step or block-step in use
2479 * This function should be called when a signal has successfully been
2480 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2481 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2482 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2484 static void signal_delivered(struct ksignal *ksig, int stepping)
2488 /* A signal was successfully delivered, and the
2489 saved sigmask was stored on the signal frame,
2490 and will be restored by sigreturn. So we can
2491 simply clear the restore sigmask flag. */
2492 clear_restore_sigmask();
2494 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2495 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2496 sigaddset(&blocked, ksig->sig);
2497 set_current_blocked(&blocked);
2498 tracehook_signal_handler(stepping);
2501 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2504 force_sigsegv(ksig->sig, current);
2506 signal_delivered(ksig, stepping);
2510 * It could be that complete_signal() picked us to notify about the
2511 * group-wide signal. Other threads should be notified now to take
2512 * the shared signals in @which since we will not.
2514 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2517 struct task_struct *t;
2519 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2520 if (sigisemptyset(&retarget))
2524 while_each_thread(tsk, t) {
2525 if (t->flags & PF_EXITING)
2528 if (!has_pending_signals(&retarget, &t->blocked))
2530 /* Remove the signals this thread can handle. */
2531 sigandsets(&retarget, &retarget, &t->blocked);
2533 if (!signal_pending(t))
2534 signal_wake_up(t, 0);
2536 if (sigisemptyset(&retarget))
2541 void exit_signals(struct task_struct *tsk)
2547 * @tsk is about to have PF_EXITING set - lock out users which
2548 * expect stable threadgroup.
2550 cgroup_threadgroup_change_begin(tsk);
2552 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2553 tsk->flags |= PF_EXITING;
2554 cgroup_threadgroup_change_end(tsk);
2558 spin_lock_irq(&tsk->sighand->siglock);
2560 * From now this task is not visible for group-wide signals,
2561 * see wants_signal(), do_signal_stop().
2563 tsk->flags |= PF_EXITING;
2565 cgroup_threadgroup_change_end(tsk);
2567 if (!signal_pending(tsk))
2570 unblocked = tsk->blocked;
2571 signotset(&unblocked);
2572 retarget_shared_pending(tsk, &unblocked);
2574 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2575 task_participate_group_stop(tsk))
2576 group_stop = CLD_STOPPED;
2578 spin_unlock_irq(&tsk->sighand->siglock);
2581 * If group stop has completed, deliver the notification. This
2582 * should always go to the real parent of the group leader.
2584 if (unlikely(group_stop)) {
2585 read_lock(&tasklist_lock);
2586 do_notify_parent_cldstop(tsk, false, group_stop);
2587 read_unlock(&tasklist_lock);
2591 EXPORT_SYMBOL(recalc_sigpending);
2592 EXPORT_SYMBOL_GPL(dequeue_signal);
2593 EXPORT_SYMBOL(flush_signals);
2594 EXPORT_SYMBOL(force_sig);
2595 EXPORT_SYMBOL(send_sig);
2596 EXPORT_SYMBOL(send_sig_info);
2597 EXPORT_SYMBOL(sigprocmask);
2600 * System call entry points.
2604 * sys_restart_syscall - restart a system call
2606 SYSCALL_DEFINE0(restart_syscall)
2608 struct restart_block *restart = ¤t->restart_block;
2609 return restart->fn(restart);
2612 long do_no_restart_syscall(struct restart_block *param)
2617 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2619 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2620 sigset_t newblocked;
2621 /* A set of now blocked but previously unblocked signals. */
2622 sigandnsets(&newblocked, newset, ¤t->blocked);
2623 retarget_shared_pending(tsk, &newblocked);
2625 tsk->blocked = *newset;
2626 recalc_sigpending();
2630 * set_current_blocked - change current->blocked mask
2633 * It is wrong to change ->blocked directly, this helper should be used
2634 * to ensure the process can't miss a shared signal we are going to block.
2636 void set_current_blocked(sigset_t *newset)
2638 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2639 __set_current_blocked(newset);
2642 void __set_current_blocked(const sigset_t *newset)
2644 struct task_struct *tsk = current;
2647 * In case the signal mask hasn't changed, there is nothing we need
2648 * to do. The current->blocked shouldn't be modified by other task.
2650 if (sigequalsets(&tsk->blocked, newset))
2653 spin_lock_irq(&tsk->sighand->siglock);
2654 __set_task_blocked(tsk, newset);
2655 spin_unlock_irq(&tsk->sighand->siglock);
2659 * This is also useful for kernel threads that want to temporarily
2660 * (or permanently) block certain signals.
2662 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2663 * interface happily blocks "unblockable" signals like SIGKILL
2666 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2668 struct task_struct *tsk = current;
2671 /* Lockless, only current can change ->blocked, never from irq */
2673 *oldset = tsk->blocked;
2677 sigorsets(&newset, &tsk->blocked, set);
2680 sigandnsets(&newset, &tsk->blocked, set);
2689 __set_current_blocked(&newset);
2694 * sys_rt_sigprocmask - change the list of currently blocked signals
2695 * @how: whether to add, remove, or set signals
2696 * @nset: stores pending signals
2697 * @oset: previous value of signal mask if non-null
2698 * @sigsetsize: size of sigset_t type
2700 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2701 sigset_t __user *, oset, size_t, sigsetsize)
2703 sigset_t old_set, new_set;
2706 /* XXX: Don't preclude handling different sized sigset_t's. */
2707 if (sigsetsize != sizeof(sigset_t))
2710 old_set = current->blocked;
2713 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2715 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2717 error = sigprocmask(how, &new_set, NULL);
2723 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2730 #ifdef CONFIG_COMPAT
2731 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2732 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2734 sigset_t old_set = current->blocked;
2736 /* XXX: Don't preclude handling different sized sigset_t's. */
2737 if (sigsetsize != sizeof(sigset_t))
2743 if (get_compat_sigset(&new_set, nset))
2745 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2747 error = sigprocmask(how, &new_set, NULL);
2751 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
2755 static int do_sigpending(sigset_t *set)
2757 spin_lock_irq(¤t->sighand->siglock);
2758 sigorsets(set, ¤t->pending.signal,
2759 ¤t->signal->shared_pending.signal);
2760 spin_unlock_irq(¤t->sighand->siglock);
2762 /* Outside the lock because only this thread touches it. */
2763 sigandsets(set, ¤t->blocked, set);
2768 * sys_rt_sigpending - examine a pending signal that has been raised
2770 * @uset: stores pending signals
2771 * @sigsetsize: size of sigset_t type or larger
2773 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2778 if (sigsetsize > sizeof(*uset))
2781 err = do_sigpending(&set);
2782 if (!err && copy_to_user(uset, &set, sigsetsize))
2787 #ifdef CONFIG_COMPAT
2788 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2789 compat_size_t, sigsetsize)
2794 if (sigsetsize > sizeof(*uset))
2797 err = do_sigpending(&set);
2799 err = put_compat_sigset(uset, &set, sigsetsize);
2804 enum siginfo_layout siginfo_layout(int sig, int si_code)
2806 enum siginfo_layout layout = SIL_KILL;
2807 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
2808 static const struct {
2809 unsigned char limit, layout;
2811 [SIGILL] = { NSIGILL, SIL_FAULT },
2812 [SIGFPE] = { NSIGFPE, SIL_FAULT },
2813 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
2814 [SIGBUS] = { NSIGBUS, SIL_FAULT },
2815 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
2816 #if defined(SIGEMT) && defined(NSIGEMT)
2817 [SIGEMT] = { NSIGEMT, SIL_FAULT },
2819 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
2820 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
2821 [SIGSYS] = { NSIGSYS, SIL_SYS },
2823 if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit)) {
2824 layout = filter[sig].layout;
2825 /* Handle the exceptions */
2826 if ((sig == SIGBUS) &&
2827 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
2828 layout = SIL_FAULT_MCEERR;
2829 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
2830 layout = SIL_FAULT_BNDERR;
2832 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
2833 layout = SIL_FAULT_PKUERR;
2836 else if (si_code <= NSIGPOLL)
2839 if (si_code == SI_TIMER)
2841 else if (si_code == SI_SIGIO)
2843 else if (si_code < 0)
2849 int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2851 if (copy_to_user(to, from , sizeof(struct siginfo)))
2856 #ifdef CONFIG_COMPAT
2857 int copy_siginfo_to_user32(struct compat_siginfo __user *to,
2858 const struct siginfo *from)
2859 #if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
2861 return __copy_siginfo_to_user32(to, from, in_x32_syscall());
2863 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
2864 const struct siginfo *from, bool x32_ABI)
2867 struct compat_siginfo new;
2868 memset(&new, 0, sizeof(new));
2870 new.si_signo = from->si_signo;
2871 new.si_errno = from->si_errno;
2872 new.si_code = from->si_code;
2873 switch(siginfo_layout(from->si_signo, from->si_code)) {
2875 new.si_pid = from->si_pid;
2876 new.si_uid = from->si_uid;
2879 new.si_tid = from->si_tid;
2880 new.si_overrun = from->si_overrun;
2881 new.si_int = from->si_int;
2884 new.si_band = from->si_band;
2885 new.si_fd = from->si_fd;
2888 new.si_addr = ptr_to_compat(from->si_addr);
2889 #ifdef __ARCH_SI_TRAPNO
2890 new.si_trapno = from->si_trapno;
2893 case SIL_FAULT_MCEERR:
2894 new.si_addr = ptr_to_compat(from->si_addr);
2895 #ifdef __ARCH_SI_TRAPNO
2896 new.si_trapno = from->si_trapno;
2898 new.si_addr_lsb = from->si_addr_lsb;
2900 case SIL_FAULT_BNDERR:
2901 new.si_addr = ptr_to_compat(from->si_addr);
2902 #ifdef __ARCH_SI_TRAPNO
2903 new.si_trapno = from->si_trapno;
2905 new.si_lower = ptr_to_compat(from->si_lower);
2906 new.si_upper = ptr_to_compat(from->si_upper);
2908 case SIL_FAULT_PKUERR:
2909 new.si_addr = ptr_to_compat(from->si_addr);
2910 #ifdef __ARCH_SI_TRAPNO
2911 new.si_trapno = from->si_trapno;
2913 new.si_pkey = from->si_pkey;
2916 new.si_pid = from->si_pid;
2917 new.si_uid = from->si_uid;
2918 new.si_status = from->si_status;
2919 #ifdef CONFIG_X86_X32_ABI
2921 new._sifields._sigchld_x32._utime = from->si_utime;
2922 new._sifields._sigchld_x32._stime = from->si_stime;
2926 new.si_utime = from->si_utime;
2927 new.si_stime = from->si_stime;
2931 new.si_pid = from->si_pid;
2932 new.si_uid = from->si_uid;
2933 new.si_int = from->si_int;
2936 new.si_call_addr = ptr_to_compat(from->si_call_addr);
2937 new.si_syscall = from->si_syscall;
2938 new.si_arch = from->si_arch;
2942 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
2948 int copy_siginfo_from_user32(struct siginfo *to,
2949 const struct compat_siginfo __user *ufrom)
2951 struct compat_siginfo from;
2953 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
2957 to->si_signo = from.si_signo;
2958 to->si_errno = from.si_errno;
2959 to->si_code = from.si_code;
2960 switch(siginfo_layout(from.si_signo, from.si_code)) {
2962 to->si_pid = from.si_pid;
2963 to->si_uid = from.si_uid;
2966 to->si_tid = from.si_tid;
2967 to->si_overrun = from.si_overrun;
2968 to->si_int = from.si_int;
2971 to->si_band = from.si_band;
2972 to->si_fd = from.si_fd;
2975 to->si_addr = compat_ptr(from.si_addr);
2976 #ifdef __ARCH_SI_TRAPNO
2977 to->si_trapno = from.si_trapno;
2980 case SIL_FAULT_MCEERR:
2981 to->si_addr = compat_ptr(from.si_addr);
2982 #ifdef __ARCH_SI_TRAPNO
2983 to->si_trapno = from.si_trapno;
2985 to->si_addr_lsb = from.si_addr_lsb;
2987 case SIL_FAULT_BNDERR:
2988 to->si_addr = compat_ptr(from.si_addr);
2989 #ifdef __ARCH_SI_TRAPNO
2990 to->si_trapno = from.si_trapno;
2992 to->si_lower = compat_ptr(from.si_lower);
2993 to->si_upper = compat_ptr(from.si_upper);
2995 case SIL_FAULT_PKUERR:
2996 to->si_addr = compat_ptr(from.si_addr);
2997 #ifdef __ARCH_SI_TRAPNO
2998 to->si_trapno = from.si_trapno;
3000 to->si_pkey = from.si_pkey;
3003 to->si_pid = from.si_pid;
3004 to->si_uid = from.si_uid;
3005 to->si_status = from.si_status;
3006 #ifdef CONFIG_X86_X32_ABI
3007 if (in_x32_syscall()) {
3008 to->si_utime = from._sifields._sigchld_x32._utime;
3009 to->si_stime = from._sifields._sigchld_x32._stime;
3013 to->si_utime = from.si_utime;
3014 to->si_stime = from.si_stime;
3018 to->si_pid = from.si_pid;
3019 to->si_uid = from.si_uid;
3020 to->si_int = from.si_int;
3023 to->si_call_addr = compat_ptr(from.si_call_addr);
3024 to->si_syscall = from.si_syscall;
3025 to->si_arch = from.si_arch;
3030 #endif /* CONFIG_COMPAT */
3033 * do_sigtimedwait - wait for queued signals specified in @which
3034 * @which: queued signals to wait for
3035 * @info: if non-null, the signal's siginfo is returned here
3036 * @ts: upper bound on process time suspension
3038 static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
3039 const struct timespec *ts)
3041 ktime_t *to = NULL, timeout = KTIME_MAX;
3042 struct task_struct *tsk = current;
3043 sigset_t mask = *which;
3047 if (!timespec_valid(ts))
3049 timeout = timespec_to_ktime(*ts);
3054 * Invert the set of allowed signals to get those we want to block.
3056 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3059 spin_lock_irq(&tsk->sighand->siglock);
3060 sig = dequeue_signal(tsk, &mask, info);
3061 if (!sig && timeout) {
3063 * None ready, temporarily unblock those we're interested
3064 * while we are sleeping in so that we'll be awakened when
3065 * they arrive. Unblocking is always fine, we can avoid
3066 * set_current_blocked().
3068 tsk->real_blocked = tsk->blocked;
3069 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3070 recalc_sigpending();
3071 spin_unlock_irq(&tsk->sighand->siglock);
3073 __set_current_state(TASK_INTERRUPTIBLE);
3074 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3076 spin_lock_irq(&tsk->sighand->siglock);
3077 __set_task_blocked(tsk, &tsk->real_blocked);
3078 sigemptyset(&tsk->real_blocked);
3079 sig = dequeue_signal(tsk, &mask, info);
3081 spin_unlock_irq(&tsk->sighand->siglock);
3085 return ret ? -EINTR : -EAGAIN;
3089 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3091 * @uthese: queued signals to wait for
3092 * @uinfo: if non-null, the signal's siginfo is returned here
3093 * @uts: upper bound on process time suspension
3094 * @sigsetsize: size of sigset_t type
3096 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3097 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
3105 /* XXX: Don't preclude handling different sized sigset_t's. */
3106 if (sigsetsize != sizeof(sigset_t))
3109 if (copy_from_user(&these, uthese, sizeof(these)))
3113 if (copy_from_user(&ts, uts, sizeof(ts)))
3117 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3119 if (ret > 0 && uinfo) {
3120 if (copy_siginfo_to_user(uinfo, &info))
3127 #ifdef CONFIG_COMPAT
3128 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
3129 struct compat_siginfo __user *, uinfo,
3130 struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
3137 if (sigsetsize != sizeof(sigset_t))
3140 if (get_compat_sigset(&s, uthese))
3144 if (compat_get_timespec(&t, uts))
3148 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3150 if (ret > 0 && uinfo) {
3151 if (copy_siginfo_to_user32(uinfo, &info))
3160 * sys_kill - send a signal to a process
3161 * @pid: the PID of the process
3162 * @sig: signal to be sent
3164 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3166 struct siginfo info;
3168 clear_siginfo(&info);
3169 info.si_signo = sig;
3171 info.si_code = SI_USER;
3172 info.si_pid = task_tgid_vnr(current);
3173 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3175 return kill_something_info(sig, &info, pid);
3179 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
3181 struct task_struct *p;
3185 p = find_task_by_vpid(pid);
3186 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3187 error = check_kill_permission(sig, info, p);
3189 * The null signal is a permissions and process existence
3190 * probe. No signal is actually delivered.
3192 if (!error && sig) {
3193 error = do_send_sig_info(sig, info, p, false);
3195 * If lock_task_sighand() failed we pretend the task
3196 * dies after receiving the signal. The window is tiny,
3197 * and the signal is private anyway.
3199 if (unlikely(error == -ESRCH))
3208 static int do_tkill(pid_t tgid, pid_t pid, int sig)
3210 struct siginfo info;
3212 clear_siginfo(&info);
3213 info.si_signo = sig;
3215 info.si_code = SI_TKILL;
3216 info.si_pid = task_tgid_vnr(current);
3217 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3219 return do_send_specific(tgid, pid, sig, &info);
3223 * sys_tgkill - send signal to one specific thread
3224 * @tgid: the thread group ID of the thread
3225 * @pid: the PID of the thread
3226 * @sig: signal to be sent
3228 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3229 * exists but it's not belonging to the target process anymore. This
3230 * method solves the problem of threads exiting and PIDs getting reused.
3232 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3234 /* This is only valid for single tasks */
3235 if (pid <= 0 || tgid <= 0)
3238 return do_tkill(tgid, pid, sig);
3242 * sys_tkill - send signal to one specific task
3243 * @pid: the PID of the task
3244 * @sig: signal to be sent
3246 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3248 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3250 /* This is only valid for single tasks */
3254 return do_tkill(0, pid, sig);
3257 static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3259 /* Not even root can pretend to send signals from the kernel.
3260 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3262 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3263 (task_pid_vnr(current) != pid))
3266 info->si_signo = sig;
3268 /* POSIX.1b doesn't mention process groups. */
3269 return kill_proc_info(sig, info, pid);
3273 * sys_rt_sigqueueinfo - send signal information to a signal
3274 * @pid: the PID of the thread
3275 * @sig: signal to be sent
3276 * @uinfo: signal info to be sent
3278 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3279 siginfo_t __user *, uinfo)
3282 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3284 return do_rt_sigqueueinfo(pid, sig, &info);
3287 #ifdef CONFIG_COMPAT
3288 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3291 struct compat_siginfo __user *, uinfo)
3294 int ret = copy_siginfo_from_user32(&info, uinfo);
3297 return do_rt_sigqueueinfo(pid, sig, &info);
3301 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3303 /* This is only valid for single tasks */
3304 if (pid <= 0 || tgid <= 0)
3307 /* Not even root can pretend to send signals from the kernel.
3308 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3310 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3311 (task_pid_vnr(current) != pid))
3314 info->si_signo = sig;
3316 return do_send_specific(tgid, pid, sig, info);
3319 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3320 siginfo_t __user *, uinfo)
3324 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3327 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3330 #ifdef CONFIG_COMPAT
3331 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3335 struct compat_siginfo __user *, uinfo)
3339 if (copy_siginfo_from_user32(&info, uinfo))
3341 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3346 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3348 void kernel_sigaction(int sig, __sighandler_t action)
3350 spin_lock_irq(¤t->sighand->siglock);
3351 current->sighand->action[sig - 1].sa.sa_handler = action;
3352 if (action == SIG_IGN) {
3356 sigaddset(&mask, sig);
3358 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3359 flush_sigqueue_mask(&mask, ¤t->pending);
3360 recalc_sigpending();
3362 spin_unlock_irq(¤t->sighand->siglock);
3364 EXPORT_SYMBOL(kernel_sigaction);
3366 void __weak sigaction_compat_abi(struct k_sigaction *act,
3367 struct k_sigaction *oact)
3371 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3373 struct task_struct *p = current, *t;
3374 struct k_sigaction *k;
3377 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3380 k = &p->sighand->action[sig-1];
3382 spin_lock_irq(&p->sighand->siglock);
3386 sigaction_compat_abi(act, oact);
3389 sigdelsetmask(&act->sa.sa_mask,
3390 sigmask(SIGKILL) | sigmask(SIGSTOP));
3394 * "Setting a signal action to SIG_IGN for a signal that is
3395 * pending shall cause the pending signal to be discarded,
3396 * whether or not it is blocked."
3398 * "Setting a signal action to SIG_DFL for a signal that is
3399 * pending and whose default action is to ignore the signal
3400 * (for example, SIGCHLD), shall cause the pending signal to
3401 * be discarded, whether or not it is blocked"
3403 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3405 sigaddset(&mask, sig);
3406 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3407 for_each_thread(p, t)
3408 flush_sigqueue_mask(&mask, &t->pending);
3412 spin_unlock_irq(&p->sighand->siglock);
3417 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
3419 struct task_struct *t = current;
3422 memset(oss, 0, sizeof(stack_t));
3423 oss->ss_sp = (void __user *) t->sas_ss_sp;
3424 oss->ss_size = t->sas_ss_size;
3425 oss->ss_flags = sas_ss_flags(sp) |
3426 (current->sas_ss_flags & SS_FLAG_BITS);
3430 void __user *ss_sp = ss->ss_sp;
3431 size_t ss_size = ss->ss_size;
3432 unsigned ss_flags = ss->ss_flags;
3435 if (unlikely(on_sig_stack(sp)))
3438 ss_mode = ss_flags & ~SS_FLAG_BITS;
3439 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3443 if (ss_mode == SS_DISABLE) {
3447 if (unlikely(ss_size < MINSIGSTKSZ))
3451 t->sas_ss_sp = (unsigned long) ss_sp;
3452 t->sas_ss_size = ss_size;
3453 t->sas_ss_flags = ss_flags;
3458 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3462 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
3464 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
3465 current_user_stack_pointer());
3466 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
3471 int restore_altstack(const stack_t __user *uss)
3474 if (copy_from_user(&new, uss, sizeof(stack_t)))
3476 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
3477 /* squash all but EFAULT for now */
3481 int __save_altstack(stack_t __user *uss, unsigned long sp)
3483 struct task_struct *t = current;
3484 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3485 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3486 __put_user(t->sas_ss_size, &uss->ss_size);
3489 if (t->sas_ss_flags & SS_AUTODISARM)
3494 #ifdef CONFIG_COMPAT
3495 static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
3496 compat_stack_t __user *uoss_ptr)
3502 compat_stack_t uss32;
3503 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3505 uss.ss_sp = compat_ptr(uss32.ss_sp);
3506 uss.ss_flags = uss32.ss_flags;
3507 uss.ss_size = uss32.ss_size;
3509 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
3510 compat_user_stack_pointer());
3511 if (ret >= 0 && uoss_ptr) {
3513 memset(&old, 0, sizeof(old));
3514 old.ss_sp = ptr_to_compat(uoss.ss_sp);
3515 old.ss_flags = uoss.ss_flags;
3516 old.ss_size = uoss.ss_size;
3517 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
3523 COMPAT_SYSCALL_DEFINE2(sigaltstack,
3524 const compat_stack_t __user *, uss_ptr,
3525 compat_stack_t __user *, uoss_ptr)
3527 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
3530 int compat_restore_altstack(const compat_stack_t __user *uss)
3532 int err = do_compat_sigaltstack(uss, NULL);
3533 /* squash all but -EFAULT for now */
3534 return err == -EFAULT ? err : 0;
3537 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3540 struct task_struct *t = current;
3541 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3543 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3544 __put_user(t->sas_ss_size, &uss->ss_size);
3547 if (t->sas_ss_flags & SS_AUTODISARM)
3553 #ifdef __ARCH_WANT_SYS_SIGPENDING
3556 * sys_sigpending - examine pending signals
3557 * @uset: where mask of pending signal is returned
3559 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
3564 if (sizeof(old_sigset_t) > sizeof(*uset))
3567 err = do_sigpending(&set);
3568 if (!err && copy_to_user(uset, &set, sizeof(old_sigset_t)))
3573 #ifdef CONFIG_COMPAT
3574 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
3577 int err = do_sigpending(&set);
3579 err = put_user(set.sig[0], set32);
3586 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3588 * sys_sigprocmask - examine and change blocked signals
3589 * @how: whether to add, remove, or set signals
3590 * @nset: signals to add or remove (if non-null)
3591 * @oset: previous value of signal mask if non-null
3593 * Some platforms have their own version with special arguments;
3594 * others support only sys_rt_sigprocmask.
3597 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3598 old_sigset_t __user *, oset)
3600 old_sigset_t old_set, new_set;
3601 sigset_t new_blocked;
3603 old_set = current->blocked.sig[0];
3606 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3609 new_blocked = current->blocked;
3613 sigaddsetmask(&new_blocked, new_set);
3616 sigdelsetmask(&new_blocked, new_set);
3619 new_blocked.sig[0] = new_set;
3625 set_current_blocked(&new_blocked);
3629 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3635 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3637 #ifndef CONFIG_ODD_RT_SIGACTION
3639 * sys_rt_sigaction - alter an action taken by a process
3640 * @sig: signal to be sent
3641 * @act: new sigaction
3642 * @oact: used to save the previous sigaction
3643 * @sigsetsize: size of sigset_t type
3645 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3646 const struct sigaction __user *, act,
3647 struct sigaction __user *, oact,
3650 struct k_sigaction new_sa, old_sa;
3653 /* XXX: Don't preclude handling different sized sigset_t's. */
3654 if (sigsetsize != sizeof(sigset_t))
3658 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3662 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3665 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3671 #ifdef CONFIG_COMPAT
3672 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3673 const struct compat_sigaction __user *, act,
3674 struct compat_sigaction __user *, oact,
3675 compat_size_t, sigsetsize)
3677 struct k_sigaction new_ka, old_ka;
3678 #ifdef __ARCH_HAS_SA_RESTORER
3679 compat_uptr_t restorer;
3683 /* XXX: Don't preclude handling different sized sigset_t's. */
3684 if (sigsetsize != sizeof(compat_sigset_t))
3688 compat_uptr_t handler;
3689 ret = get_user(handler, &act->sa_handler);
3690 new_ka.sa.sa_handler = compat_ptr(handler);
3691 #ifdef __ARCH_HAS_SA_RESTORER
3692 ret |= get_user(restorer, &act->sa_restorer);
3693 new_ka.sa.sa_restorer = compat_ptr(restorer);
3695 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
3696 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3701 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3703 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3705 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
3706 sizeof(oact->sa_mask));
3707 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3708 #ifdef __ARCH_HAS_SA_RESTORER
3709 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3710 &oact->sa_restorer);
3716 #endif /* !CONFIG_ODD_RT_SIGACTION */
3718 #ifdef CONFIG_OLD_SIGACTION
3719 SYSCALL_DEFINE3(sigaction, int, sig,
3720 const struct old_sigaction __user *, act,
3721 struct old_sigaction __user *, oact)
3723 struct k_sigaction new_ka, old_ka;
3728 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3729 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3730 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3731 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3732 __get_user(mask, &act->sa_mask))
3734 #ifdef __ARCH_HAS_KA_RESTORER
3735 new_ka.ka_restorer = NULL;
3737 siginitset(&new_ka.sa.sa_mask, mask);
3740 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3743 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3744 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3745 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3746 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3747 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3754 #ifdef CONFIG_COMPAT_OLD_SIGACTION
3755 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3756 const struct compat_old_sigaction __user *, act,
3757 struct compat_old_sigaction __user *, oact)
3759 struct k_sigaction new_ka, old_ka;
3761 compat_old_sigset_t mask;
3762 compat_uptr_t handler, restorer;
3765 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3766 __get_user(handler, &act->sa_handler) ||
3767 __get_user(restorer, &act->sa_restorer) ||
3768 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3769 __get_user(mask, &act->sa_mask))
3772 #ifdef __ARCH_HAS_KA_RESTORER
3773 new_ka.ka_restorer = NULL;
3775 new_ka.sa.sa_handler = compat_ptr(handler);
3776 new_ka.sa.sa_restorer = compat_ptr(restorer);
3777 siginitset(&new_ka.sa.sa_mask, mask);
3780 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3783 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3784 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3785 &oact->sa_handler) ||
3786 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3787 &oact->sa_restorer) ||
3788 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3789 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3796 #ifdef CONFIG_SGETMASK_SYSCALL
3799 * For backwards compatibility. Functionality superseded by sigprocmask.
3801 SYSCALL_DEFINE0(sgetmask)
3804 return current->blocked.sig[0];
3807 SYSCALL_DEFINE1(ssetmask, int, newmask)
3809 int old = current->blocked.sig[0];
3812 siginitset(&newset, newmask);
3813 set_current_blocked(&newset);
3817 #endif /* CONFIG_SGETMASK_SYSCALL */
3819 #ifdef __ARCH_WANT_SYS_SIGNAL
3821 * For backwards compatibility. Functionality superseded by sigaction.
3823 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3825 struct k_sigaction new_sa, old_sa;
3828 new_sa.sa.sa_handler = handler;
3829 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3830 sigemptyset(&new_sa.sa.sa_mask);
3832 ret = do_sigaction(sig, &new_sa, &old_sa);
3834 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3836 #endif /* __ARCH_WANT_SYS_SIGNAL */
3838 #ifdef __ARCH_WANT_SYS_PAUSE
3840 SYSCALL_DEFINE0(pause)
3842 while (!signal_pending(current)) {
3843 __set_current_state(TASK_INTERRUPTIBLE);
3846 return -ERESTARTNOHAND;
3851 static int sigsuspend(sigset_t *set)
3853 current->saved_sigmask = current->blocked;
3854 set_current_blocked(set);
3856 while (!signal_pending(current)) {
3857 __set_current_state(TASK_INTERRUPTIBLE);
3860 set_restore_sigmask();
3861 return -ERESTARTNOHAND;
3865 * sys_rt_sigsuspend - replace the signal mask for a value with the
3866 * @unewset value until a signal is received
3867 * @unewset: new signal mask value
3868 * @sigsetsize: size of sigset_t type
3870 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3874 /* XXX: Don't preclude handling different sized sigset_t's. */
3875 if (sigsetsize != sizeof(sigset_t))
3878 if (copy_from_user(&newset, unewset, sizeof(newset)))
3880 return sigsuspend(&newset);
3883 #ifdef CONFIG_COMPAT
3884 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3888 /* XXX: Don't preclude handling different sized sigset_t's. */
3889 if (sigsetsize != sizeof(sigset_t))
3892 if (get_compat_sigset(&newset, unewset))
3894 return sigsuspend(&newset);
3898 #ifdef CONFIG_OLD_SIGSUSPEND
3899 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3902 siginitset(&blocked, mask);
3903 return sigsuspend(&blocked);
3906 #ifdef CONFIG_OLD_SIGSUSPEND3
3907 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3910 siginitset(&blocked, mask);
3911 return sigsuspend(&blocked);
3915 __weak const char *arch_vma_name(struct vm_area_struct *vma)
3920 void __init signals_init(void)
3922 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3923 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3924 != offsetof(struct siginfo, _sifields._pad));
3925 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
3927 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3930 #ifdef CONFIG_KGDB_KDB
3931 #include <linux/kdb.h>
3933 * kdb_send_sig - Allows kdb to send signals without exposing
3934 * signal internals. This function checks if the required locks are
3935 * available before calling the main signal code, to avoid kdb
3938 void kdb_send_sig(struct task_struct *t, int sig)
3940 static struct task_struct *kdb_prev_t;
3942 if (!spin_trylock(&t->sighand->siglock)) {
3943 kdb_printf("Can't do kill command now.\n"
3944 "The sigmask lock is held somewhere else in "
3945 "kernel, try again later\n");
3948 new_t = kdb_prev_t != t;
3950 if (t->state != TASK_RUNNING && new_t) {
3951 spin_unlock(&t->sighand->siglock);
3952 kdb_printf("Process is not RUNNING, sending a signal from "
3953 "kdb risks deadlock\n"
3954 "on the run queue locks. "
3955 "The signal has _not_ been sent.\n"
3956 "Reissue the kill command if you want to risk "
3960 ret = send_signal(sig, SEND_SIG_PRIV, t, false);
3961 spin_unlock(&t->sighand->siglock);
3963 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3966 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3968 #endif /* CONFIG_KGDB_KDB */