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 inline bool 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 bool kill_ok_by_cred(struct task_struct *t)
722 const struct cred *cred = current_cred();
723 const struct cred *tcred = __task_cred(t);
725 return 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) ||
729 ns_capable(tcred->user_ns, CAP_KILL);
733 * Bad permissions for sending the signal
734 * - the caller must hold the RCU read lock
736 static int check_kill_permission(int sig, struct siginfo *info,
737 struct task_struct *t)
742 if (!valid_signal(sig))
745 if (!si_fromuser(info))
748 error = audit_signal_info(sig, t); /* Let audit system see the signal */
752 if (!same_thread_group(current, t) &&
753 !kill_ok_by_cred(t)) {
756 sid = task_session(t);
758 * We don't return the error if sid == NULL. The
759 * task was unhashed, the caller must notice this.
761 if (!sid || sid == task_session(current))
768 return security_task_kill(t, info, sig, NULL);
772 * ptrace_trap_notify - schedule trap to notify ptracer
773 * @t: tracee wanting to notify tracer
775 * This function schedules sticky ptrace trap which is cleared on the next
776 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
779 * If @t is running, STOP trap will be taken. If trapped for STOP and
780 * ptracer is listening for events, tracee is woken up so that it can
781 * re-trap for the new event. If trapped otherwise, STOP trap will be
782 * eventually taken without returning to userland after the existing traps
783 * are finished by PTRACE_CONT.
786 * Must be called with @task->sighand->siglock held.
788 static void ptrace_trap_notify(struct task_struct *t)
790 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
791 assert_spin_locked(&t->sighand->siglock);
793 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
794 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
798 * Handle magic process-wide effects of stop/continue signals. Unlike
799 * the signal actions, these happen immediately at signal-generation
800 * time regardless of blocking, ignoring, or handling. This does the
801 * actual continuing for SIGCONT, but not the actual stopping for stop
802 * signals. The process stop is done as a signal action for SIG_DFL.
804 * Returns true if the signal should be actually delivered, otherwise
805 * it should be dropped.
807 static bool prepare_signal(int sig, struct task_struct *p, bool force)
809 struct signal_struct *signal = p->signal;
810 struct task_struct *t;
813 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
814 if (!(signal->flags & SIGNAL_GROUP_EXIT))
815 return sig == SIGKILL;
817 * The process is in the middle of dying, nothing to do.
819 } else if (sig_kernel_stop(sig)) {
821 * This is a stop signal. Remove SIGCONT from all queues.
823 siginitset(&flush, sigmask(SIGCONT));
824 flush_sigqueue_mask(&flush, &signal->shared_pending);
825 for_each_thread(p, t)
826 flush_sigqueue_mask(&flush, &t->pending);
827 } else if (sig == SIGCONT) {
830 * Remove all stop signals from all queues, wake all threads.
832 siginitset(&flush, SIG_KERNEL_STOP_MASK);
833 flush_sigqueue_mask(&flush, &signal->shared_pending);
834 for_each_thread(p, t) {
835 flush_sigqueue_mask(&flush, &t->pending);
836 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
837 if (likely(!(t->ptrace & PT_SEIZED)))
838 wake_up_state(t, __TASK_STOPPED);
840 ptrace_trap_notify(t);
844 * Notify the parent with CLD_CONTINUED if we were stopped.
846 * If we were in the middle of a group stop, we pretend it
847 * was already finished, and then continued. Since SIGCHLD
848 * doesn't queue we report only CLD_STOPPED, as if the next
849 * CLD_CONTINUED was dropped.
852 if (signal->flags & SIGNAL_STOP_STOPPED)
853 why |= SIGNAL_CLD_CONTINUED;
854 else if (signal->group_stop_count)
855 why |= SIGNAL_CLD_STOPPED;
859 * The first thread which returns from do_signal_stop()
860 * will take ->siglock, notice SIGNAL_CLD_MASK, and
861 * notify its parent. See get_signal_to_deliver().
863 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
864 signal->group_stop_count = 0;
865 signal->group_exit_code = 0;
869 return !sig_ignored(p, sig, force);
873 * Test if P wants to take SIG. After we've checked all threads with this,
874 * it's equivalent to finding no threads not blocking SIG. Any threads not
875 * blocking SIG were ruled out because they are not running and already
876 * have pending signals. Such threads will dequeue from the shared queue
877 * as soon as they're available, so putting the signal on the shared queue
878 * will be equivalent to sending it to one such thread.
880 static inline int wants_signal(int sig, struct task_struct *p)
882 if (sigismember(&p->blocked, sig))
884 if (p->flags & PF_EXITING)
888 if (task_is_stopped_or_traced(p))
890 return task_curr(p) || !signal_pending(p);
893 static void complete_signal(int sig, struct task_struct *p, int group)
895 struct signal_struct *signal = p->signal;
896 struct task_struct *t;
899 * Now find a thread we can wake up to take the signal off the queue.
901 * If the main thread wants the signal, it gets first crack.
902 * Probably the least surprising to the average bear.
904 if (wants_signal(sig, p))
906 else if (!group || thread_group_empty(p))
908 * There is just one thread and it does not need to be woken.
909 * It will dequeue unblocked signals before it runs again.
914 * Otherwise try to find a suitable thread.
916 t = signal->curr_target;
917 while (!wants_signal(sig, t)) {
919 if (t == signal->curr_target)
921 * No thread needs to be woken.
922 * Any eligible threads will see
923 * the signal in the queue soon.
927 signal->curr_target = t;
931 * Found a killable thread. If the signal will be fatal,
932 * then start taking the whole group down immediately.
934 if (sig_fatal(p, sig) &&
935 !(signal->flags & SIGNAL_GROUP_EXIT) &&
936 !sigismember(&t->real_blocked, sig) &&
937 (sig == SIGKILL || !p->ptrace)) {
939 * This signal will be fatal to the whole group.
941 if (!sig_kernel_coredump(sig)) {
943 * Start a group exit and wake everybody up.
944 * This way we don't have other threads
945 * running and doing things after a slower
946 * thread has the fatal signal pending.
948 signal->flags = SIGNAL_GROUP_EXIT;
949 signal->group_exit_code = sig;
950 signal->group_stop_count = 0;
953 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
954 sigaddset(&t->pending.signal, SIGKILL);
955 signal_wake_up(t, 1);
956 } while_each_thread(p, t);
962 * The signal is already in the shared-pending queue.
963 * Tell the chosen thread to wake up and dequeue it.
965 signal_wake_up(t, sig == SIGKILL);
969 static inline int legacy_queue(struct sigpending *signals, int sig)
971 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
974 #ifdef CONFIG_USER_NS
975 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
977 if (current_user_ns() == task_cred_xxx(t, user_ns))
980 if (SI_FROMKERNEL(info))
984 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
985 make_kuid(current_user_ns(), info->si_uid));
989 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
995 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
996 int group, int from_ancestor_ns)
998 struct sigpending *pending;
1000 int override_rlimit;
1001 int ret = 0, result;
1003 assert_spin_locked(&t->sighand->siglock);
1005 result = TRACE_SIGNAL_IGNORED;
1006 if (!prepare_signal(sig, t,
1007 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1010 pending = group ? &t->signal->shared_pending : &t->pending;
1012 * Short-circuit ignored signals and support queuing
1013 * exactly one non-rt signal, so that we can get more
1014 * detailed information about the cause of the signal.
1016 result = TRACE_SIGNAL_ALREADY_PENDING;
1017 if (legacy_queue(pending, sig))
1020 result = TRACE_SIGNAL_DELIVERED;
1022 * fast-pathed signals for kernel-internal things like SIGSTOP
1025 if (info == SEND_SIG_FORCED)
1029 * Real-time signals must be queued if sent by sigqueue, or
1030 * some other real-time mechanism. It is implementation
1031 * defined whether kill() does so. We attempt to do so, on
1032 * the principle of least surprise, but since kill is not
1033 * allowed to fail with EAGAIN when low on memory we just
1034 * make sure at least one signal gets delivered and don't
1035 * pass on the info struct.
1038 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1040 override_rlimit = 0;
1042 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1044 list_add_tail(&q->list, &pending->list);
1045 switch ((unsigned long) info) {
1046 case (unsigned long) SEND_SIG_NOINFO:
1047 clear_siginfo(&q->info);
1048 q->info.si_signo = sig;
1049 q->info.si_errno = 0;
1050 q->info.si_code = SI_USER;
1051 q->info.si_pid = task_tgid_nr_ns(current,
1052 task_active_pid_ns(t));
1053 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1055 case (unsigned long) SEND_SIG_PRIV:
1056 clear_siginfo(&q->info);
1057 q->info.si_signo = sig;
1058 q->info.si_errno = 0;
1059 q->info.si_code = SI_KERNEL;
1064 copy_siginfo(&q->info, info);
1065 if (from_ancestor_ns)
1070 userns_fixup_signal_uid(&q->info, t);
1072 } else if (!is_si_special(info)) {
1073 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1075 * Queue overflow, abort. We may abort if the
1076 * signal was rt and sent by user using something
1077 * other than kill().
1079 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1084 * This is a silent loss of information. We still
1085 * send the signal, but the *info bits are lost.
1087 result = TRACE_SIGNAL_LOSE_INFO;
1092 signalfd_notify(t, sig);
1093 sigaddset(&pending->signal, sig);
1094 complete_signal(sig, t, group);
1096 trace_signal_generate(sig, info, t, group, result);
1100 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1103 int from_ancestor_ns = 0;
1105 #ifdef CONFIG_PID_NS
1106 from_ancestor_ns = si_fromuser(info) &&
1107 !task_pid_nr_ns(current, task_active_pid_ns(t));
1110 return __send_signal(sig, info, t, group, from_ancestor_ns);
1113 static void print_fatal_signal(int signr)
1115 struct pt_regs *regs = signal_pt_regs();
1116 pr_info("potentially unexpected fatal signal %d.\n", signr);
1118 #if defined(__i386__) && !defined(__arch_um__)
1119 pr_info("code at %08lx: ", regs->ip);
1122 for (i = 0; i < 16; i++) {
1125 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1127 pr_cont("%02x ", insn);
1137 static int __init setup_print_fatal_signals(char *str)
1139 get_option (&str, &print_fatal_signals);
1144 __setup("print-fatal-signals=", setup_print_fatal_signals);
1147 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1149 return send_signal(sig, info, p, 1);
1153 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1155 return send_signal(sig, info, t, 0);
1158 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1161 unsigned long flags;
1164 if (lock_task_sighand(p, &flags)) {
1165 ret = send_signal(sig, info, p, group);
1166 unlock_task_sighand(p, &flags);
1173 * Force a signal that the process can't ignore: if necessary
1174 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1176 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1177 * since we do not want to have a signal handler that was blocked
1178 * be invoked when user space had explicitly blocked it.
1180 * We don't want to have recursive SIGSEGV's etc, for example,
1181 * that is why we also clear SIGNAL_UNKILLABLE.
1184 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1186 unsigned long int flags;
1187 int ret, blocked, ignored;
1188 struct k_sigaction *action;
1190 spin_lock_irqsave(&t->sighand->siglock, flags);
1191 action = &t->sighand->action[sig-1];
1192 ignored = action->sa.sa_handler == SIG_IGN;
1193 blocked = sigismember(&t->blocked, sig);
1194 if (blocked || ignored) {
1195 action->sa.sa_handler = SIG_DFL;
1197 sigdelset(&t->blocked, sig);
1198 recalc_sigpending_and_wake(t);
1202 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1203 * debugging to leave init killable.
1205 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1206 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1207 ret = specific_send_sig_info(sig, info, t);
1208 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1214 * Nuke all other threads in the group.
1216 int zap_other_threads(struct task_struct *p)
1218 struct task_struct *t = p;
1221 p->signal->group_stop_count = 0;
1223 while_each_thread(p, t) {
1224 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1227 /* Don't bother with already dead threads */
1230 sigaddset(&t->pending.signal, SIGKILL);
1231 signal_wake_up(t, 1);
1237 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1238 unsigned long *flags)
1240 struct sighand_struct *sighand;
1244 sighand = rcu_dereference(tsk->sighand);
1245 if (unlikely(sighand == NULL))
1249 * This sighand can be already freed and even reused, but
1250 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1251 * initializes ->siglock: this slab can't go away, it has
1252 * the same object type, ->siglock can't be reinitialized.
1254 * We need to ensure that tsk->sighand is still the same
1255 * after we take the lock, we can race with de_thread() or
1256 * __exit_signal(). In the latter case the next iteration
1257 * must see ->sighand == NULL.
1259 spin_lock_irqsave(&sighand->siglock, *flags);
1260 if (likely(sighand == tsk->sighand))
1262 spin_unlock_irqrestore(&sighand->siglock, *flags);
1270 * send signal info to all the members of a group
1272 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1277 ret = check_kill_permission(sig, info, p);
1281 ret = do_send_sig_info(sig, info, p, true);
1287 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1288 * control characters do (^C, ^Z etc)
1289 * - the caller must hold at least a readlock on tasklist_lock
1291 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1293 struct task_struct *p = NULL;
1294 int retval, success;
1298 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1299 int err = group_send_sig_info(sig, info, p);
1302 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1303 return success ? 0 : retval;
1306 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1309 struct task_struct *p;
1313 p = pid_task(pid, PIDTYPE_PID);
1315 error = group_send_sig_info(sig, info, p);
1317 if (likely(!p || error != -ESRCH))
1321 * The task was unhashed in between, try again. If it
1322 * is dead, pid_task() will return NULL, if we race with
1323 * de_thread() it will find the new leader.
1328 static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1332 error = kill_pid_info(sig, info, find_vpid(pid));
1337 static inline bool kill_as_cred_perm(const struct cred *cred,
1338 struct task_struct *target)
1340 const struct cred *pcred = __task_cred(target);
1342 return uid_eq(cred->euid, pcred->suid) ||
1343 uid_eq(cred->euid, pcred->uid) ||
1344 uid_eq(cred->uid, pcred->suid) ||
1345 uid_eq(cred->uid, pcred->uid);
1348 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1349 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1350 const struct cred *cred)
1353 struct task_struct *p;
1354 unsigned long flags;
1356 if (!valid_signal(sig))
1360 p = pid_task(pid, PIDTYPE_PID);
1365 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1369 ret = security_task_kill(p, info, sig, cred);
1374 if (lock_task_sighand(p, &flags)) {
1375 ret = __send_signal(sig, info, p, 1, 0);
1376 unlock_task_sighand(p, &flags);
1384 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1387 * kill_something_info() interprets pid in interesting ways just like kill(2).
1389 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1390 * is probably wrong. Should make it like BSD or SYSV.
1393 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1399 ret = kill_pid_info(sig, info, find_vpid(pid));
1404 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1408 read_lock(&tasklist_lock);
1410 ret = __kill_pgrp_info(sig, info,
1411 pid ? find_vpid(-pid) : task_pgrp(current));
1413 int retval = 0, count = 0;
1414 struct task_struct * p;
1416 for_each_process(p) {
1417 if (task_pid_vnr(p) > 1 &&
1418 !same_thread_group(p, current)) {
1419 int err = group_send_sig_info(sig, info, p);
1425 ret = count ? retval : -ESRCH;
1427 read_unlock(&tasklist_lock);
1433 * These are for backward compatibility with the rest of the kernel source.
1436 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1439 * Make sure legacy kernel users don't send in bad values
1440 * (normal paths check this in check_kill_permission).
1442 if (!valid_signal(sig))
1445 return do_send_sig_info(sig, info, p, false);
1448 #define __si_special(priv) \
1449 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1452 send_sig(int sig, struct task_struct *p, int priv)
1454 return send_sig_info(sig, __si_special(priv), p);
1457 void force_sig(int sig, struct task_struct *p)
1459 force_sig_info(sig, SEND_SIG_PRIV, p);
1463 * When things go south during signal handling, we
1464 * will force a SIGSEGV. And if the signal that caused
1465 * the problem was already a SIGSEGV, we'll want to
1466 * make sure we don't even try to deliver the signal..
1468 void force_sigsegv(int sig, struct task_struct *p)
1470 if (sig == SIGSEGV) {
1471 unsigned long flags;
1472 spin_lock_irqsave(&p->sighand->siglock, flags);
1473 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1474 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1476 force_sig(SIGSEGV, p);
1479 int force_sig_fault(int sig, int code, void __user *addr
1480 ___ARCH_SI_TRAPNO(int trapno)
1481 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1482 , struct task_struct *t)
1484 struct siginfo info;
1486 clear_siginfo(&info);
1487 info.si_signo = sig;
1489 info.si_code = code;
1490 info.si_addr = addr;
1491 #ifdef __ARCH_SI_TRAPNO
1492 info.si_trapno = trapno;
1496 info.si_flags = flags;
1499 return force_sig_info(info.si_signo, &info, t);
1502 int send_sig_fault(int sig, int code, void __user *addr
1503 ___ARCH_SI_TRAPNO(int trapno)
1504 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1505 , struct task_struct *t)
1507 struct siginfo info;
1509 clear_siginfo(&info);
1510 info.si_signo = sig;
1512 info.si_code = code;
1513 info.si_addr = addr;
1514 #ifdef __ARCH_SI_TRAPNO
1515 info.si_trapno = trapno;
1519 info.si_flags = flags;
1522 return send_sig_info(info.si_signo, &info, t);
1525 int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1527 struct siginfo info;
1529 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1530 clear_siginfo(&info);
1531 info.si_signo = SIGBUS;
1533 info.si_code = code;
1534 info.si_addr = addr;
1535 info.si_addr_lsb = lsb;
1536 return force_sig_info(info.si_signo, &info, t);
1539 int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1541 struct siginfo info;
1543 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1544 clear_siginfo(&info);
1545 info.si_signo = SIGBUS;
1547 info.si_code = code;
1548 info.si_addr = addr;
1549 info.si_addr_lsb = lsb;
1550 return send_sig_info(info.si_signo, &info, t);
1552 EXPORT_SYMBOL(send_sig_mceerr);
1554 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1556 struct siginfo info;
1558 clear_siginfo(&info);
1559 info.si_signo = SIGSEGV;
1561 info.si_code = SEGV_BNDERR;
1562 info.si_addr = addr;
1563 info.si_lower = lower;
1564 info.si_upper = upper;
1565 return force_sig_info(info.si_signo, &info, current);
1569 int force_sig_pkuerr(void __user *addr, u32 pkey)
1571 struct siginfo info;
1573 clear_siginfo(&info);
1574 info.si_signo = SIGSEGV;
1576 info.si_code = SEGV_PKUERR;
1577 info.si_addr = addr;
1578 info.si_pkey = pkey;
1579 return force_sig_info(info.si_signo, &info, current);
1583 /* For the crazy architectures that include trap information in
1584 * the errno field, instead of an actual errno value.
1586 int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1588 struct siginfo info;
1590 clear_siginfo(&info);
1591 info.si_signo = SIGTRAP;
1592 info.si_errno = errno;
1593 info.si_code = TRAP_HWBKPT;
1594 info.si_addr = addr;
1595 return force_sig_info(info.si_signo, &info, current);
1598 int kill_pgrp(struct pid *pid, int sig, int priv)
1602 read_lock(&tasklist_lock);
1603 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1604 read_unlock(&tasklist_lock);
1608 EXPORT_SYMBOL(kill_pgrp);
1610 int kill_pid(struct pid *pid, int sig, int priv)
1612 return kill_pid_info(sig, __si_special(priv), pid);
1614 EXPORT_SYMBOL(kill_pid);
1617 * These functions support sending signals using preallocated sigqueue
1618 * structures. This is needed "because realtime applications cannot
1619 * afford to lose notifications of asynchronous events, like timer
1620 * expirations or I/O completions". In the case of POSIX Timers
1621 * we allocate the sigqueue structure from the timer_create. If this
1622 * allocation fails we are able to report the failure to the application
1623 * with an EAGAIN error.
1625 struct sigqueue *sigqueue_alloc(void)
1627 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1630 q->flags |= SIGQUEUE_PREALLOC;
1635 void sigqueue_free(struct sigqueue *q)
1637 unsigned long flags;
1638 spinlock_t *lock = ¤t->sighand->siglock;
1640 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1642 * We must hold ->siglock while testing q->list
1643 * to serialize with collect_signal() or with
1644 * __exit_signal()->flush_sigqueue().
1646 spin_lock_irqsave(lock, flags);
1647 q->flags &= ~SIGQUEUE_PREALLOC;
1649 * If it is queued it will be freed when dequeued,
1650 * like the "regular" sigqueue.
1652 if (!list_empty(&q->list))
1654 spin_unlock_irqrestore(lock, flags);
1660 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1662 int sig = q->info.si_signo;
1663 struct sigpending *pending;
1664 unsigned long flags;
1667 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1670 if (!likely(lock_task_sighand(t, &flags)))
1673 ret = 1; /* the signal is ignored */
1674 result = TRACE_SIGNAL_IGNORED;
1675 if (!prepare_signal(sig, t, false))
1679 if (unlikely(!list_empty(&q->list))) {
1681 * If an SI_TIMER entry is already queue just increment
1682 * the overrun count.
1684 BUG_ON(q->info.si_code != SI_TIMER);
1685 q->info.si_overrun++;
1686 result = TRACE_SIGNAL_ALREADY_PENDING;
1689 q->info.si_overrun = 0;
1691 signalfd_notify(t, sig);
1692 pending = group ? &t->signal->shared_pending : &t->pending;
1693 list_add_tail(&q->list, &pending->list);
1694 sigaddset(&pending->signal, sig);
1695 complete_signal(sig, t, group);
1696 result = TRACE_SIGNAL_DELIVERED;
1698 trace_signal_generate(sig, &q->info, t, group, result);
1699 unlock_task_sighand(t, &flags);
1705 * Let a parent know about the death of a child.
1706 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1708 * Returns true if our parent ignored us and so we've switched to
1711 bool do_notify_parent(struct task_struct *tsk, int sig)
1713 struct siginfo info;
1714 unsigned long flags;
1715 struct sighand_struct *psig;
1716 bool autoreap = false;
1721 /* do_notify_parent_cldstop should have been called instead. */
1722 BUG_ON(task_is_stopped_or_traced(tsk));
1724 BUG_ON(!tsk->ptrace &&
1725 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1727 if (sig != SIGCHLD) {
1729 * This is only possible if parent == real_parent.
1730 * Check if it has changed security domain.
1732 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1736 clear_siginfo(&info);
1737 info.si_signo = sig;
1740 * We are under tasklist_lock here so our parent is tied to
1741 * us and cannot change.
1743 * task_active_pid_ns will always return the same pid namespace
1744 * until a task passes through release_task.
1746 * write_lock() currently calls preempt_disable() which is the
1747 * same as rcu_read_lock(), but according to Oleg, this is not
1748 * correct to rely on this
1751 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1752 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1756 task_cputime(tsk, &utime, &stime);
1757 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1758 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1760 info.si_status = tsk->exit_code & 0x7f;
1761 if (tsk->exit_code & 0x80)
1762 info.si_code = CLD_DUMPED;
1763 else if (tsk->exit_code & 0x7f)
1764 info.si_code = CLD_KILLED;
1766 info.si_code = CLD_EXITED;
1767 info.si_status = tsk->exit_code >> 8;
1770 psig = tsk->parent->sighand;
1771 spin_lock_irqsave(&psig->siglock, flags);
1772 if (!tsk->ptrace && sig == SIGCHLD &&
1773 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1774 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1776 * We are exiting and our parent doesn't care. POSIX.1
1777 * defines special semantics for setting SIGCHLD to SIG_IGN
1778 * or setting the SA_NOCLDWAIT flag: we should be reaped
1779 * automatically and not left for our parent's wait4 call.
1780 * Rather than having the parent do it as a magic kind of
1781 * signal handler, we just set this to tell do_exit that we
1782 * can be cleaned up without becoming a zombie. Note that
1783 * we still call __wake_up_parent in this case, because a
1784 * blocked sys_wait4 might now return -ECHILD.
1786 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1787 * is implementation-defined: we do (if you don't want
1788 * it, just use SIG_IGN instead).
1791 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1794 if (valid_signal(sig) && sig)
1795 __group_send_sig_info(sig, &info, tsk->parent);
1796 __wake_up_parent(tsk, tsk->parent);
1797 spin_unlock_irqrestore(&psig->siglock, flags);
1803 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1804 * @tsk: task reporting the state change
1805 * @for_ptracer: the notification is for ptracer
1806 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1808 * Notify @tsk's parent that the stopped/continued state has changed. If
1809 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1810 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1813 * Must be called with tasklist_lock at least read locked.
1815 static void do_notify_parent_cldstop(struct task_struct *tsk,
1816 bool for_ptracer, int why)
1818 struct siginfo info;
1819 unsigned long flags;
1820 struct task_struct *parent;
1821 struct sighand_struct *sighand;
1825 parent = tsk->parent;
1827 tsk = tsk->group_leader;
1828 parent = tsk->real_parent;
1831 clear_siginfo(&info);
1832 info.si_signo = SIGCHLD;
1835 * see comment in do_notify_parent() about the following 4 lines
1838 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1839 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1842 task_cputime(tsk, &utime, &stime);
1843 info.si_utime = nsec_to_clock_t(utime);
1844 info.si_stime = nsec_to_clock_t(stime);
1849 info.si_status = SIGCONT;
1852 info.si_status = tsk->signal->group_exit_code & 0x7f;
1855 info.si_status = tsk->exit_code & 0x7f;
1861 sighand = parent->sighand;
1862 spin_lock_irqsave(&sighand->siglock, flags);
1863 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1864 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1865 __group_send_sig_info(SIGCHLD, &info, parent);
1867 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1869 __wake_up_parent(tsk, parent);
1870 spin_unlock_irqrestore(&sighand->siglock, flags);
1873 static inline bool may_ptrace_stop(void)
1875 if (!likely(current->ptrace))
1878 * Are we in the middle of do_coredump?
1879 * If so and our tracer is also part of the coredump stopping
1880 * is a deadlock situation, and pointless because our tracer
1881 * is dead so don't allow us to stop.
1882 * If SIGKILL was already sent before the caller unlocked
1883 * ->siglock we must see ->core_state != NULL. Otherwise it
1884 * is safe to enter schedule().
1886 * This is almost outdated, a task with the pending SIGKILL can't
1887 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1888 * after SIGKILL was already dequeued.
1890 if (unlikely(current->mm->core_state) &&
1891 unlikely(current->mm == current->parent->mm))
1898 * Return non-zero if there is a SIGKILL that should be waking us up.
1899 * Called with the siglock held.
1901 static int sigkill_pending(struct task_struct *tsk)
1903 return sigismember(&tsk->pending.signal, SIGKILL) ||
1904 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1908 * This must be called with current->sighand->siglock held.
1910 * This should be the path for all ptrace stops.
1911 * We always set current->last_siginfo while stopped here.
1912 * That makes it a way to test a stopped process for
1913 * being ptrace-stopped vs being job-control-stopped.
1915 * If we actually decide not to stop at all because the tracer
1916 * is gone, we keep current->exit_code unless clear_code.
1918 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1919 __releases(¤t->sighand->siglock)
1920 __acquires(¤t->sighand->siglock)
1922 bool gstop_done = false;
1924 if (arch_ptrace_stop_needed(exit_code, info)) {
1926 * The arch code has something special to do before a
1927 * ptrace stop. This is allowed to block, e.g. for faults
1928 * on user stack pages. We can't keep the siglock while
1929 * calling arch_ptrace_stop, so we must release it now.
1930 * To preserve proper semantics, we must do this before
1931 * any signal bookkeeping like checking group_stop_count.
1932 * Meanwhile, a SIGKILL could come in before we retake the
1933 * siglock. That must prevent us from sleeping in TASK_TRACED.
1934 * So after regaining the lock, we must check for SIGKILL.
1936 spin_unlock_irq(¤t->sighand->siglock);
1937 arch_ptrace_stop(exit_code, info);
1938 spin_lock_irq(¤t->sighand->siglock);
1939 if (sigkill_pending(current))
1943 set_special_state(TASK_TRACED);
1946 * We're committing to trapping. TRACED should be visible before
1947 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1948 * Also, transition to TRACED and updates to ->jobctl should be
1949 * atomic with respect to siglock and should be done after the arch
1950 * hook as siglock is released and regrabbed across it.
1955 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
1957 * set_current_state() smp_wmb();
1959 * wait_task_stopped()
1960 * task_stopped_code()
1961 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
1965 current->last_siginfo = info;
1966 current->exit_code = exit_code;
1969 * If @why is CLD_STOPPED, we're trapping to participate in a group
1970 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1971 * across siglock relocks since INTERRUPT was scheduled, PENDING
1972 * could be clear now. We act as if SIGCONT is received after
1973 * TASK_TRACED is entered - ignore it.
1975 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1976 gstop_done = task_participate_group_stop(current);
1978 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1979 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1980 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1981 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1983 /* entering a trap, clear TRAPPING */
1984 task_clear_jobctl_trapping(current);
1986 spin_unlock_irq(¤t->sighand->siglock);
1987 read_lock(&tasklist_lock);
1988 if (may_ptrace_stop()) {
1990 * Notify parents of the stop.
1992 * While ptraced, there are two parents - the ptracer and
1993 * the real_parent of the group_leader. The ptracer should
1994 * know about every stop while the real parent is only
1995 * interested in the completion of group stop. The states
1996 * for the two don't interact with each other. Notify
1997 * separately unless they're gonna be duplicates.
1999 do_notify_parent_cldstop(current, true, why);
2000 if (gstop_done && ptrace_reparented(current))
2001 do_notify_parent_cldstop(current, false, why);
2004 * Don't want to allow preemption here, because
2005 * sys_ptrace() needs this task to be inactive.
2007 * XXX: implement read_unlock_no_resched().
2010 read_unlock(&tasklist_lock);
2011 preempt_enable_no_resched();
2012 freezable_schedule();
2015 * By the time we got the lock, our tracer went away.
2016 * Don't drop the lock yet, another tracer may come.
2018 * If @gstop_done, the ptracer went away between group stop
2019 * completion and here. During detach, it would have set
2020 * JOBCTL_STOP_PENDING on us and we'll re-enter
2021 * TASK_STOPPED in do_signal_stop() on return, so notifying
2022 * the real parent of the group stop completion is enough.
2025 do_notify_parent_cldstop(current, false, why);
2027 /* tasklist protects us from ptrace_freeze_traced() */
2028 __set_current_state(TASK_RUNNING);
2030 current->exit_code = 0;
2031 read_unlock(&tasklist_lock);
2035 * We are back. Now reacquire the siglock before touching
2036 * last_siginfo, so that we are sure to have synchronized with
2037 * any signal-sending on another CPU that wants to examine it.
2039 spin_lock_irq(¤t->sighand->siglock);
2040 current->last_siginfo = NULL;
2042 /* LISTENING can be set only during STOP traps, clear it */
2043 current->jobctl &= ~JOBCTL_LISTENING;
2046 * Queued signals ignored us while we were stopped for tracing.
2047 * So check for any that we should take before resuming user mode.
2048 * This sets TIF_SIGPENDING, but never clears it.
2050 recalc_sigpending_tsk(current);
2053 static void ptrace_do_notify(int signr, int exit_code, int why)
2057 clear_siginfo(&info);
2058 info.si_signo = signr;
2059 info.si_code = exit_code;
2060 info.si_pid = task_pid_vnr(current);
2061 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2063 /* Let the debugger run. */
2064 ptrace_stop(exit_code, why, 1, &info);
2067 void ptrace_notify(int exit_code)
2069 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2070 if (unlikely(current->task_works))
2073 spin_lock_irq(¤t->sighand->siglock);
2074 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2075 spin_unlock_irq(¤t->sighand->siglock);
2079 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2080 * @signr: signr causing group stop if initiating
2082 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2083 * and participate in it. If already set, participate in the existing
2084 * group stop. If participated in a group stop (and thus slept), %true is
2085 * returned with siglock released.
2087 * If ptraced, this function doesn't handle stop itself. Instead,
2088 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2089 * untouched. The caller must ensure that INTERRUPT trap handling takes
2090 * places afterwards.
2093 * Must be called with @current->sighand->siglock held, which is released
2097 * %false if group stop is already cancelled or ptrace trap is scheduled.
2098 * %true if participated in group stop.
2100 static bool do_signal_stop(int signr)
2101 __releases(¤t->sighand->siglock)
2103 struct signal_struct *sig = current->signal;
2105 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2106 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2107 struct task_struct *t;
2109 /* signr will be recorded in task->jobctl for retries */
2110 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2112 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2113 unlikely(signal_group_exit(sig)))
2116 * There is no group stop already in progress. We must
2119 * While ptraced, a task may be resumed while group stop is
2120 * still in effect and then receive a stop signal and
2121 * initiate another group stop. This deviates from the
2122 * usual behavior as two consecutive stop signals can't
2123 * cause two group stops when !ptraced. That is why we
2124 * also check !task_is_stopped(t) below.
2126 * The condition can be distinguished by testing whether
2127 * SIGNAL_STOP_STOPPED is already set. Don't generate
2128 * group_exit_code in such case.
2130 * This is not necessary for SIGNAL_STOP_CONTINUED because
2131 * an intervening stop signal is required to cause two
2132 * continued events regardless of ptrace.
2134 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2135 sig->group_exit_code = signr;
2137 sig->group_stop_count = 0;
2139 if (task_set_jobctl_pending(current, signr | gstop))
2140 sig->group_stop_count++;
2143 while_each_thread(current, t) {
2145 * Setting state to TASK_STOPPED for a group
2146 * stop is always done with the siglock held,
2147 * so this check has no races.
2149 if (!task_is_stopped(t) &&
2150 task_set_jobctl_pending(t, signr | gstop)) {
2151 sig->group_stop_count++;
2152 if (likely(!(t->ptrace & PT_SEIZED)))
2153 signal_wake_up(t, 0);
2155 ptrace_trap_notify(t);
2160 if (likely(!current->ptrace)) {
2164 * If there are no other threads in the group, or if there
2165 * is a group stop in progress and we are the last to stop,
2166 * report to the parent.
2168 if (task_participate_group_stop(current))
2169 notify = CLD_STOPPED;
2171 set_special_state(TASK_STOPPED);
2172 spin_unlock_irq(¤t->sighand->siglock);
2175 * Notify the parent of the group stop completion. Because
2176 * we're not holding either the siglock or tasklist_lock
2177 * here, ptracer may attach inbetween; however, this is for
2178 * group stop and should always be delivered to the real
2179 * parent of the group leader. The new ptracer will get
2180 * its notification when this task transitions into
2184 read_lock(&tasklist_lock);
2185 do_notify_parent_cldstop(current, false, notify);
2186 read_unlock(&tasklist_lock);
2189 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2190 freezable_schedule();
2194 * While ptraced, group stop is handled by STOP trap.
2195 * Schedule it and let the caller deal with it.
2197 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2203 * do_jobctl_trap - take care of ptrace jobctl traps
2205 * When PT_SEIZED, it's used for both group stop and explicit
2206 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2207 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2208 * the stop signal; otherwise, %SIGTRAP.
2210 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2211 * number as exit_code and no siginfo.
2214 * Must be called with @current->sighand->siglock held, which may be
2215 * released and re-acquired before returning with intervening sleep.
2217 static void do_jobctl_trap(void)
2219 struct signal_struct *signal = current->signal;
2220 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2222 if (current->ptrace & PT_SEIZED) {
2223 if (!signal->group_stop_count &&
2224 !(signal->flags & SIGNAL_STOP_STOPPED))
2226 WARN_ON_ONCE(!signr);
2227 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2230 WARN_ON_ONCE(!signr);
2231 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2232 current->exit_code = 0;
2236 static int ptrace_signal(int signr, siginfo_t *info)
2239 * We do not check sig_kernel_stop(signr) but set this marker
2240 * unconditionally because we do not know whether debugger will
2241 * change signr. This flag has no meaning unless we are going
2242 * to stop after return from ptrace_stop(). In this case it will
2243 * be checked in do_signal_stop(), we should only stop if it was
2244 * not cleared by SIGCONT while we were sleeping. See also the
2245 * comment in dequeue_signal().
2247 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2248 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2250 /* We're back. Did the debugger cancel the sig? */
2251 signr = current->exit_code;
2255 current->exit_code = 0;
2258 * Update the siginfo structure if the signal has
2259 * changed. If the debugger wanted something
2260 * specific in the siginfo structure then it should
2261 * have updated *info via PTRACE_SETSIGINFO.
2263 if (signr != info->si_signo) {
2264 clear_siginfo(info);
2265 info->si_signo = signr;
2267 info->si_code = SI_USER;
2269 info->si_pid = task_pid_vnr(current->parent);
2270 info->si_uid = from_kuid_munged(current_user_ns(),
2271 task_uid(current->parent));
2275 /* If the (new) signal is now blocked, requeue it. */
2276 if (sigismember(¤t->blocked, signr)) {
2277 specific_send_sig_info(signr, info, current);
2284 int get_signal(struct ksignal *ksig)
2286 struct sighand_struct *sighand = current->sighand;
2287 struct signal_struct *signal = current->signal;
2290 if (unlikely(current->task_works))
2293 if (unlikely(uprobe_deny_signal()))
2297 * Do this once, we can't return to user-mode if freezing() == T.
2298 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2299 * thus do not need another check after return.
2304 spin_lock_irq(&sighand->siglock);
2306 * Every stopped thread goes here after wakeup. Check to see if
2307 * we should notify the parent, prepare_signal(SIGCONT) encodes
2308 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2310 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2313 if (signal->flags & SIGNAL_CLD_CONTINUED)
2314 why = CLD_CONTINUED;
2318 signal->flags &= ~SIGNAL_CLD_MASK;
2320 spin_unlock_irq(&sighand->siglock);
2323 * Notify the parent that we're continuing. This event is
2324 * always per-process and doesn't make whole lot of sense
2325 * for ptracers, who shouldn't consume the state via
2326 * wait(2) either, but, for backward compatibility, notify
2327 * the ptracer of the group leader too unless it's gonna be
2330 read_lock(&tasklist_lock);
2331 do_notify_parent_cldstop(current, false, why);
2333 if (ptrace_reparented(current->group_leader))
2334 do_notify_parent_cldstop(current->group_leader,
2336 read_unlock(&tasklist_lock);
2342 struct k_sigaction *ka;
2344 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2348 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2350 spin_unlock_irq(&sighand->siglock);
2354 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2357 break; /* will return 0 */
2359 if (unlikely(current->ptrace) && signr != SIGKILL) {
2360 signr = ptrace_signal(signr, &ksig->info);
2365 ka = &sighand->action[signr-1];
2367 /* Trace actually delivered signals. */
2368 trace_signal_deliver(signr, &ksig->info, ka);
2370 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2372 if (ka->sa.sa_handler != SIG_DFL) {
2373 /* Run the handler. */
2376 if (ka->sa.sa_flags & SA_ONESHOT)
2377 ka->sa.sa_handler = SIG_DFL;
2379 break; /* will return non-zero "signr" value */
2383 * Now we are doing the default action for this signal.
2385 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2389 * Global init gets no signals it doesn't want.
2390 * Container-init gets no signals it doesn't want from same
2393 * Note that if global/container-init sees a sig_kernel_only()
2394 * signal here, the signal must have been generated internally
2395 * or must have come from an ancestor namespace. In either
2396 * case, the signal cannot be dropped.
2398 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2399 !sig_kernel_only(signr))
2402 if (sig_kernel_stop(signr)) {
2404 * The default action is to stop all threads in
2405 * the thread group. The job control signals
2406 * do nothing in an orphaned pgrp, but SIGSTOP
2407 * always works. Note that siglock needs to be
2408 * dropped during the call to is_orphaned_pgrp()
2409 * because of lock ordering with tasklist_lock.
2410 * This allows an intervening SIGCONT to be posted.
2411 * We need to check for that and bail out if necessary.
2413 if (signr != SIGSTOP) {
2414 spin_unlock_irq(&sighand->siglock);
2416 /* signals can be posted during this window */
2418 if (is_current_pgrp_orphaned())
2421 spin_lock_irq(&sighand->siglock);
2424 if (likely(do_signal_stop(ksig->info.si_signo))) {
2425 /* It released the siglock. */
2430 * We didn't actually stop, due to a race
2431 * with SIGCONT or something like that.
2436 spin_unlock_irq(&sighand->siglock);
2439 * Anything else is fatal, maybe with a core dump.
2441 current->flags |= PF_SIGNALED;
2443 if (sig_kernel_coredump(signr)) {
2444 if (print_fatal_signals)
2445 print_fatal_signal(ksig->info.si_signo);
2446 proc_coredump_connector(current);
2448 * If it was able to dump core, this kills all
2449 * other threads in the group and synchronizes with
2450 * their demise. If we lost the race with another
2451 * thread getting here, it set group_exit_code
2452 * first and our do_group_exit call below will use
2453 * that value and ignore the one we pass it.
2455 do_coredump(&ksig->info);
2459 * Death signals, no core dump.
2461 do_group_exit(ksig->info.si_signo);
2464 spin_unlock_irq(&sighand->siglock);
2467 return ksig->sig > 0;
2471 * signal_delivered -
2472 * @ksig: kernel signal struct
2473 * @stepping: nonzero if debugger single-step or block-step in use
2475 * This function should be called when a signal has successfully been
2476 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2477 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2478 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2480 static void signal_delivered(struct ksignal *ksig, int stepping)
2484 /* A signal was successfully delivered, and the
2485 saved sigmask was stored on the signal frame,
2486 and will be restored by sigreturn. So we can
2487 simply clear the restore sigmask flag. */
2488 clear_restore_sigmask();
2490 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2491 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2492 sigaddset(&blocked, ksig->sig);
2493 set_current_blocked(&blocked);
2494 tracehook_signal_handler(stepping);
2497 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2500 force_sigsegv(ksig->sig, current);
2502 signal_delivered(ksig, stepping);
2506 * It could be that complete_signal() picked us to notify about the
2507 * group-wide signal. Other threads should be notified now to take
2508 * the shared signals in @which since we will not.
2510 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2513 struct task_struct *t;
2515 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2516 if (sigisemptyset(&retarget))
2520 while_each_thread(tsk, t) {
2521 if (t->flags & PF_EXITING)
2524 if (!has_pending_signals(&retarget, &t->blocked))
2526 /* Remove the signals this thread can handle. */
2527 sigandsets(&retarget, &retarget, &t->blocked);
2529 if (!signal_pending(t))
2530 signal_wake_up(t, 0);
2532 if (sigisemptyset(&retarget))
2537 void exit_signals(struct task_struct *tsk)
2543 * @tsk is about to have PF_EXITING set - lock out users which
2544 * expect stable threadgroup.
2546 cgroup_threadgroup_change_begin(tsk);
2548 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2549 tsk->flags |= PF_EXITING;
2550 cgroup_threadgroup_change_end(tsk);
2554 spin_lock_irq(&tsk->sighand->siglock);
2556 * From now this task is not visible for group-wide signals,
2557 * see wants_signal(), do_signal_stop().
2559 tsk->flags |= PF_EXITING;
2561 cgroup_threadgroup_change_end(tsk);
2563 if (!signal_pending(tsk))
2566 unblocked = tsk->blocked;
2567 signotset(&unblocked);
2568 retarget_shared_pending(tsk, &unblocked);
2570 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2571 task_participate_group_stop(tsk))
2572 group_stop = CLD_STOPPED;
2574 spin_unlock_irq(&tsk->sighand->siglock);
2577 * If group stop has completed, deliver the notification. This
2578 * should always go to the real parent of the group leader.
2580 if (unlikely(group_stop)) {
2581 read_lock(&tasklist_lock);
2582 do_notify_parent_cldstop(tsk, false, group_stop);
2583 read_unlock(&tasklist_lock);
2587 EXPORT_SYMBOL(recalc_sigpending);
2588 EXPORT_SYMBOL_GPL(dequeue_signal);
2589 EXPORT_SYMBOL(flush_signals);
2590 EXPORT_SYMBOL(force_sig);
2591 EXPORT_SYMBOL(send_sig);
2592 EXPORT_SYMBOL(send_sig_info);
2593 EXPORT_SYMBOL(sigprocmask);
2596 * System call entry points.
2600 * sys_restart_syscall - restart a system call
2602 SYSCALL_DEFINE0(restart_syscall)
2604 struct restart_block *restart = ¤t->restart_block;
2605 return restart->fn(restart);
2608 long do_no_restart_syscall(struct restart_block *param)
2613 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2615 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2616 sigset_t newblocked;
2617 /* A set of now blocked but previously unblocked signals. */
2618 sigandnsets(&newblocked, newset, ¤t->blocked);
2619 retarget_shared_pending(tsk, &newblocked);
2621 tsk->blocked = *newset;
2622 recalc_sigpending();
2626 * set_current_blocked - change current->blocked mask
2629 * It is wrong to change ->blocked directly, this helper should be used
2630 * to ensure the process can't miss a shared signal we are going to block.
2632 void set_current_blocked(sigset_t *newset)
2634 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2635 __set_current_blocked(newset);
2638 void __set_current_blocked(const sigset_t *newset)
2640 struct task_struct *tsk = current;
2643 * In case the signal mask hasn't changed, there is nothing we need
2644 * to do. The current->blocked shouldn't be modified by other task.
2646 if (sigequalsets(&tsk->blocked, newset))
2649 spin_lock_irq(&tsk->sighand->siglock);
2650 __set_task_blocked(tsk, newset);
2651 spin_unlock_irq(&tsk->sighand->siglock);
2655 * This is also useful for kernel threads that want to temporarily
2656 * (or permanently) block certain signals.
2658 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2659 * interface happily blocks "unblockable" signals like SIGKILL
2662 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2664 struct task_struct *tsk = current;
2667 /* Lockless, only current can change ->blocked, never from irq */
2669 *oldset = tsk->blocked;
2673 sigorsets(&newset, &tsk->blocked, set);
2676 sigandnsets(&newset, &tsk->blocked, set);
2685 __set_current_blocked(&newset);
2690 * sys_rt_sigprocmask - change the list of currently blocked signals
2691 * @how: whether to add, remove, or set signals
2692 * @nset: stores pending signals
2693 * @oset: previous value of signal mask if non-null
2694 * @sigsetsize: size of sigset_t type
2696 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2697 sigset_t __user *, oset, size_t, sigsetsize)
2699 sigset_t old_set, new_set;
2702 /* XXX: Don't preclude handling different sized sigset_t's. */
2703 if (sigsetsize != sizeof(sigset_t))
2706 old_set = current->blocked;
2709 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2711 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2713 error = sigprocmask(how, &new_set, NULL);
2719 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2726 #ifdef CONFIG_COMPAT
2727 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2728 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2730 sigset_t old_set = current->blocked;
2732 /* XXX: Don't preclude handling different sized sigset_t's. */
2733 if (sigsetsize != sizeof(sigset_t))
2739 if (get_compat_sigset(&new_set, nset))
2741 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2743 error = sigprocmask(how, &new_set, NULL);
2747 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
2751 static void do_sigpending(sigset_t *set)
2753 spin_lock_irq(¤t->sighand->siglock);
2754 sigorsets(set, ¤t->pending.signal,
2755 ¤t->signal->shared_pending.signal);
2756 spin_unlock_irq(¤t->sighand->siglock);
2758 /* Outside the lock because only this thread touches it. */
2759 sigandsets(set, ¤t->blocked, set);
2763 * sys_rt_sigpending - examine a pending signal that has been raised
2765 * @uset: stores pending signals
2766 * @sigsetsize: size of sigset_t type or larger
2768 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2772 if (sigsetsize > sizeof(*uset))
2775 do_sigpending(&set);
2777 if (copy_to_user(uset, &set, sigsetsize))
2783 #ifdef CONFIG_COMPAT
2784 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2785 compat_size_t, sigsetsize)
2789 if (sigsetsize > sizeof(*uset))
2792 do_sigpending(&set);
2794 return put_compat_sigset(uset, &set, sigsetsize);
2798 enum siginfo_layout siginfo_layout(int sig, int si_code)
2800 enum siginfo_layout layout = SIL_KILL;
2801 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
2802 static const struct {
2803 unsigned char limit, layout;
2805 [SIGILL] = { NSIGILL, SIL_FAULT },
2806 [SIGFPE] = { NSIGFPE, SIL_FAULT },
2807 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
2808 [SIGBUS] = { NSIGBUS, SIL_FAULT },
2809 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
2810 #if defined(SIGEMT) && defined(NSIGEMT)
2811 [SIGEMT] = { NSIGEMT, SIL_FAULT },
2813 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
2814 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
2815 [SIGSYS] = { NSIGSYS, SIL_SYS },
2817 if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit)) {
2818 layout = filter[sig].layout;
2819 /* Handle the exceptions */
2820 if ((sig == SIGBUS) &&
2821 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
2822 layout = SIL_FAULT_MCEERR;
2823 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
2824 layout = SIL_FAULT_BNDERR;
2826 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
2827 layout = SIL_FAULT_PKUERR;
2830 else if (si_code <= NSIGPOLL)
2833 if (si_code == SI_TIMER)
2835 else if (si_code == SI_SIGIO)
2837 else if (si_code < 0)
2843 int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2845 if (copy_to_user(to, from , sizeof(struct siginfo)))
2850 #ifdef CONFIG_COMPAT
2851 int copy_siginfo_to_user32(struct compat_siginfo __user *to,
2852 const struct siginfo *from)
2853 #if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
2855 return __copy_siginfo_to_user32(to, from, in_x32_syscall());
2857 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
2858 const struct siginfo *from, bool x32_ABI)
2861 struct compat_siginfo new;
2862 memset(&new, 0, sizeof(new));
2864 new.si_signo = from->si_signo;
2865 new.si_errno = from->si_errno;
2866 new.si_code = from->si_code;
2867 switch(siginfo_layout(from->si_signo, from->si_code)) {
2869 new.si_pid = from->si_pid;
2870 new.si_uid = from->si_uid;
2873 new.si_tid = from->si_tid;
2874 new.si_overrun = from->si_overrun;
2875 new.si_int = from->si_int;
2878 new.si_band = from->si_band;
2879 new.si_fd = from->si_fd;
2882 new.si_addr = ptr_to_compat(from->si_addr);
2883 #ifdef __ARCH_SI_TRAPNO
2884 new.si_trapno = from->si_trapno;
2887 case SIL_FAULT_MCEERR:
2888 new.si_addr = ptr_to_compat(from->si_addr);
2889 #ifdef __ARCH_SI_TRAPNO
2890 new.si_trapno = from->si_trapno;
2892 new.si_addr_lsb = from->si_addr_lsb;
2894 case SIL_FAULT_BNDERR:
2895 new.si_addr = ptr_to_compat(from->si_addr);
2896 #ifdef __ARCH_SI_TRAPNO
2897 new.si_trapno = from->si_trapno;
2899 new.si_lower = ptr_to_compat(from->si_lower);
2900 new.si_upper = ptr_to_compat(from->si_upper);
2902 case SIL_FAULT_PKUERR:
2903 new.si_addr = ptr_to_compat(from->si_addr);
2904 #ifdef __ARCH_SI_TRAPNO
2905 new.si_trapno = from->si_trapno;
2907 new.si_pkey = from->si_pkey;
2910 new.si_pid = from->si_pid;
2911 new.si_uid = from->si_uid;
2912 new.si_status = from->si_status;
2913 #ifdef CONFIG_X86_X32_ABI
2915 new._sifields._sigchld_x32._utime = from->si_utime;
2916 new._sifields._sigchld_x32._stime = from->si_stime;
2920 new.si_utime = from->si_utime;
2921 new.si_stime = from->si_stime;
2925 new.si_pid = from->si_pid;
2926 new.si_uid = from->si_uid;
2927 new.si_int = from->si_int;
2930 new.si_call_addr = ptr_to_compat(from->si_call_addr);
2931 new.si_syscall = from->si_syscall;
2932 new.si_arch = from->si_arch;
2936 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
2942 int copy_siginfo_from_user32(struct siginfo *to,
2943 const struct compat_siginfo __user *ufrom)
2945 struct compat_siginfo from;
2947 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
2951 to->si_signo = from.si_signo;
2952 to->si_errno = from.si_errno;
2953 to->si_code = from.si_code;
2954 switch(siginfo_layout(from.si_signo, from.si_code)) {
2956 to->si_pid = from.si_pid;
2957 to->si_uid = from.si_uid;
2960 to->si_tid = from.si_tid;
2961 to->si_overrun = from.si_overrun;
2962 to->si_int = from.si_int;
2965 to->si_band = from.si_band;
2966 to->si_fd = from.si_fd;
2969 to->si_addr = compat_ptr(from.si_addr);
2970 #ifdef __ARCH_SI_TRAPNO
2971 to->si_trapno = from.si_trapno;
2974 case SIL_FAULT_MCEERR:
2975 to->si_addr = compat_ptr(from.si_addr);
2976 #ifdef __ARCH_SI_TRAPNO
2977 to->si_trapno = from.si_trapno;
2979 to->si_addr_lsb = from.si_addr_lsb;
2981 case SIL_FAULT_BNDERR:
2982 to->si_addr = compat_ptr(from.si_addr);
2983 #ifdef __ARCH_SI_TRAPNO
2984 to->si_trapno = from.si_trapno;
2986 to->si_lower = compat_ptr(from.si_lower);
2987 to->si_upper = compat_ptr(from.si_upper);
2989 case SIL_FAULT_PKUERR:
2990 to->si_addr = compat_ptr(from.si_addr);
2991 #ifdef __ARCH_SI_TRAPNO
2992 to->si_trapno = from.si_trapno;
2994 to->si_pkey = from.si_pkey;
2997 to->si_pid = from.si_pid;
2998 to->si_uid = from.si_uid;
2999 to->si_status = from.si_status;
3000 #ifdef CONFIG_X86_X32_ABI
3001 if (in_x32_syscall()) {
3002 to->si_utime = from._sifields._sigchld_x32._utime;
3003 to->si_stime = from._sifields._sigchld_x32._stime;
3007 to->si_utime = from.si_utime;
3008 to->si_stime = from.si_stime;
3012 to->si_pid = from.si_pid;
3013 to->si_uid = from.si_uid;
3014 to->si_int = from.si_int;
3017 to->si_call_addr = compat_ptr(from.si_call_addr);
3018 to->si_syscall = from.si_syscall;
3019 to->si_arch = from.si_arch;
3024 #endif /* CONFIG_COMPAT */
3027 * do_sigtimedwait - wait for queued signals specified in @which
3028 * @which: queued signals to wait for
3029 * @info: if non-null, the signal's siginfo is returned here
3030 * @ts: upper bound on process time suspension
3032 static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
3033 const struct timespec *ts)
3035 ktime_t *to = NULL, timeout = KTIME_MAX;
3036 struct task_struct *tsk = current;
3037 sigset_t mask = *which;
3041 if (!timespec_valid(ts))
3043 timeout = timespec_to_ktime(*ts);
3048 * Invert the set of allowed signals to get those we want to block.
3050 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3053 spin_lock_irq(&tsk->sighand->siglock);
3054 sig = dequeue_signal(tsk, &mask, info);
3055 if (!sig && timeout) {
3057 * None ready, temporarily unblock those we're interested
3058 * while we are sleeping in so that we'll be awakened when
3059 * they arrive. Unblocking is always fine, we can avoid
3060 * set_current_blocked().
3062 tsk->real_blocked = tsk->blocked;
3063 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3064 recalc_sigpending();
3065 spin_unlock_irq(&tsk->sighand->siglock);
3067 __set_current_state(TASK_INTERRUPTIBLE);
3068 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3070 spin_lock_irq(&tsk->sighand->siglock);
3071 __set_task_blocked(tsk, &tsk->real_blocked);
3072 sigemptyset(&tsk->real_blocked);
3073 sig = dequeue_signal(tsk, &mask, info);
3075 spin_unlock_irq(&tsk->sighand->siglock);
3079 return ret ? -EINTR : -EAGAIN;
3083 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3085 * @uthese: queued signals to wait for
3086 * @uinfo: if non-null, the signal's siginfo is returned here
3087 * @uts: upper bound on process time suspension
3088 * @sigsetsize: size of sigset_t type
3090 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3091 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
3099 /* XXX: Don't preclude handling different sized sigset_t's. */
3100 if (sigsetsize != sizeof(sigset_t))
3103 if (copy_from_user(&these, uthese, sizeof(these)))
3107 if (copy_from_user(&ts, uts, sizeof(ts)))
3111 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3113 if (ret > 0 && uinfo) {
3114 if (copy_siginfo_to_user(uinfo, &info))
3121 #ifdef CONFIG_COMPAT
3122 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
3123 struct compat_siginfo __user *, uinfo,
3124 struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
3131 if (sigsetsize != sizeof(sigset_t))
3134 if (get_compat_sigset(&s, uthese))
3138 if (compat_get_timespec(&t, uts))
3142 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3144 if (ret > 0 && uinfo) {
3145 if (copy_siginfo_to_user32(uinfo, &info))
3154 * sys_kill - send a signal to a process
3155 * @pid: the PID of the process
3156 * @sig: signal to be sent
3158 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3160 struct siginfo info;
3162 clear_siginfo(&info);
3163 info.si_signo = sig;
3165 info.si_code = SI_USER;
3166 info.si_pid = task_tgid_vnr(current);
3167 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3169 return kill_something_info(sig, &info, pid);
3173 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
3175 struct task_struct *p;
3179 p = find_task_by_vpid(pid);
3180 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3181 error = check_kill_permission(sig, info, p);
3183 * The null signal is a permissions and process existence
3184 * probe. No signal is actually delivered.
3186 if (!error && sig) {
3187 error = do_send_sig_info(sig, info, p, false);
3189 * If lock_task_sighand() failed we pretend the task
3190 * dies after receiving the signal. The window is tiny,
3191 * and the signal is private anyway.
3193 if (unlikely(error == -ESRCH))
3202 static int do_tkill(pid_t tgid, pid_t pid, int sig)
3204 struct siginfo info;
3206 clear_siginfo(&info);
3207 info.si_signo = sig;
3209 info.si_code = SI_TKILL;
3210 info.si_pid = task_tgid_vnr(current);
3211 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3213 return do_send_specific(tgid, pid, sig, &info);
3217 * sys_tgkill - send signal to one specific thread
3218 * @tgid: the thread group ID of the thread
3219 * @pid: the PID of the thread
3220 * @sig: signal to be sent
3222 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3223 * exists but it's not belonging to the target process anymore. This
3224 * method solves the problem of threads exiting and PIDs getting reused.
3226 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3228 /* This is only valid for single tasks */
3229 if (pid <= 0 || tgid <= 0)
3232 return do_tkill(tgid, pid, sig);
3236 * sys_tkill - send signal to one specific task
3237 * @pid: the PID of the task
3238 * @sig: signal to be sent
3240 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3242 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3244 /* This is only valid for single tasks */
3248 return do_tkill(0, pid, sig);
3251 static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3253 /* Not even root can pretend to send signals from the kernel.
3254 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3256 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3257 (task_pid_vnr(current) != pid))
3260 info->si_signo = sig;
3262 /* POSIX.1b doesn't mention process groups. */
3263 return kill_proc_info(sig, info, pid);
3267 * sys_rt_sigqueueinfo - send signal information to a signal
3268 * @pid: the PID of the thread
3269 * @sig: signal to be sent
3270 * @uinfo: signal info to be sent
3272 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3273 siginfo_t __user *, uinfo)
3276 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3278 return do_rt_sigqueueinfo(pid, sig, &info);
3281 #ifdef CONFIG_COMPAT
3282 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3285 struct compat_siginfo __user *, uinfo)
3288 int ret = copy_siginfo_from_user32(&info, uinfo);
3291 return do_rt_sigqueueinfo(pid, sig, &info);
3295 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3297 /* This is only valid for single tasks */
3298 if (pid <= 0 || tgid <= 0)
3301 /* Not even root can pretend to send signals from the kernel.
3302 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3304 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3305 (task_pid_vnr(current) != pid))
3308 info->si_signo = sig;
3310 return do_send_specific(tgid, pid, sig, info);
3313 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3314 siginfo_t __user *, uinfo)
3318 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3321 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3324 #ifdef CONFIG_COMPAT
3325 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3329 struct compat_siginfo __user *, uinfo)
3333 if (copy_siginfo_from_user32(&info, uinfo))
3335 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3340 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3342 void kernel_sigaction(int sig, __sighandler_t action)
3344 spin_lock_irq(¤t->sighand->siglock);
3345 current->sighand->action[sig - 1].sa.sa_handler = action;
3346 if (action == SIG_IGN) {
3350 sigaddset(&mask, sig);
3352 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3353 flush_sigqueue_mask(&mask, ¤t->pending);
3354 recalc_sigpending();
3356 spin_unlock_irq(¤t->sighand->siglock);
3358 EXPORT_SYMBOL(kernel_sigaction);
3360 void __weak sigaction_compat_abi(struct k_sigaction *act,
3361 struct k_sigaction *oact)
3365 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3367 struct task_struct *p = current, *t;
3368 struct k_sigaction *k;
3371 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3374 k = &p->sighand->action[sig-1];
3376 spin_lock_irq(&p->sighand->siglock);
3380 sigaction_compat_abi(act, oact);
3383 sigdelsetmask(&act->sa.sa_mask,
3384 sigmask(SIGKILL) | sigmask(SIGSTOP));
3388 * "Setting a signal action to SIG_IGN for a signal that is
3389 * pending shall cause the pending signal to be discarded,
3390 * whether or not it is blocked."
3392 * "Setting a signal action to SIG_DFL for a signal that is
3393 * pending and whose default action is to ignore the signal
3394 * (for example, SIGCHLD), shall cause the pending signal to
3395 * be discarded, whether or not it is blocked"
3397 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3399 sigaddset(&mask, sig);
3400 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3401 for_each_thread(p, t)
3402 flush_sigqueue_mask(&mask, &t->pending);
3406 spin_unlock_irq(&p->sighand->siglock);
3411 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
3413 struct task_struct *t = current;
3416 memset(oss, 0, sizeof(stack_t));
3417 oss->ss_sp = (void __user *) t->sas_ss_sp;
3418 oss->ss_size = t->sas_ss_size;
3419 oss->ss_flags = sas_ss_flags(sp) |
3420 (current->sas_ss_flags & SS_FLAG_BITS);
3424 void __user *ss_sp = ss->ss_sp;
3425 size_t ss_size = ss->ss_size;
3426 unsigned ss_flags = ss->ss_flags;
3429 if (unlikely(on_sig_stack(sp)))
3432 ss_mode = ss_flags & ~SS_FLAG_BITS;
3433 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3437 if (ss_mode == SS_DISABLE) {
3441 if (unlikely(ss_size < MINSIGSTKSZ))
3445 t->sas_ss_sp = (unsigned long) ss_sp;
3446 t->sas_ss_size = ss_size;
3447 t->sas_ss_flags = ss_flags;
3452 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3456 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
3458 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
3459 current_user_stack_pointer());
3460 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
3465 int restore_altstack(const stack_t __user *uss)
3468 if (copy_from_user(&new, uss, sizeof(stack_t)))
3470 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
3471 /* squash all but EFAULT for now */
3475 int __save_altstack(stack_t __user *uss, unsigned long sp)
3477 struct task_struct *t = current;
3478 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3479 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3480 __put_user(t->sas_ss_size, &uss->ss_size);
3483 if (t->sas_ss_flags & SS_AUTODISARM)
3488 #ifdef CONFIG_COMPAT
3489 static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
3490 compat_stack_t __user *uoss_ptr)
3496 compat_stack_t uss32;
3497 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3499 uss.ss_sp = compat_ptr(uss32.ss_sp);
3500 uss.ss_flags = uss32.ss_flags;
3501 uss.ss_size = uss32.ss_size;
3503 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
3504 compat_user_stack_pointer());
3505 if (ret >= 0 && uoss_ptr) {
3507 memset(&old, 0, sizeof(old));
3508 old.ss_sp = ptr_to_compat(uoss.ss_sp);
3509 old.ss_flags = uoss.ss_flags;
3510 old.ss_size = uoss.ss_size;
3511 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
3517 COMPAT_SYSCALL_DEFINE2(sigaltstack,
3518 const compat_stack_t __user *, uss_ptr,
3519 compat_stack_t __user *, uoss_ptr)
3521 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
3524 int compat_restore_altstack(const compat_stack_t __user *uss)
3526 int err = do_compat_sigaltstack(uss, NULL);
3527 /* squash all but -EFAULT for now */
3528 return err == -EFAULT ? err : 0;
3531 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3534 struct task_struct *t = current;
3535 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3537 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3538 __put_user(t->sas_ss_size, &uss->ss_size);
3541 if (t->sas_ss_flags & SS_AUTODISARM)
3547 #ifdef __ARCH_WANT_SYS_SIGPENDING
3550 * sys_sigpending - examine pending signals
3551 * @uset: where mask of pending signal is returned
3553 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
3557 if (sizeof(old_sigset_t) > sizeof(*uset))
3560 do_sigpending(&set);
3562 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
3568 #ifdef CONFIG_COMPAT
3569 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
3573 do_sigpending(&set);
3575 return put_user(set.sig[0], set32);
3581 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3583 * sys_sigprocmask - examine and change blocked signals
3584 * @how: whether to add, remove, or set signals
3585 * @nset: signals to add or remove (if non-null)
3586 * @oset: previous value of signal mask if non-null
3588 * Some platforms have their own version with special arguments;
3589 * others support only sys_rt_sigprocmask.
3592 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3593 old_sigset_t __user *, oset)
3595 old_sigset_t old_set, new_set;
3596 sigset_t new_blocked;
3598 old_set = current->blocked.sig[0];
3601 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3604 new_blocked = current->blocked;
3608 sigaddsetmask(&new_blocked, new_set);
3611 sigdelsetmask(&new_blocked, new_set);
3614 new_blocked.sig[0] = new_set;
3620 set_current_blocked(&new_blocked);
3624 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3630 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3632 #ifndef CONFIG_ODD_RT_SIGACTION
3634 * sys_rt_sigaction - alter an action taken by a process
3635 * @sig: signal to be sent
3636 * @act: new sigaction
3637 * @oact: used to save the previous sigaction
3638 * @sigsetsize: size of sigset_t type
3640 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3641 const struct sigaction __user *, act,
3642 struct sigaction __user *, oact,
3645 struct k_sigaction new_sa, old_sa;
3648 /* XXX: Don't preclude handling different sized sigset_t's. */
3649 if (sigsetsize != sizeof(sigset_t))
3652 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3655 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3659 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3664 #ifdef CONFIG_COMPAT
3665 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3666 const struct compat_sigaction __user *, act,
3667 struct compat_sigaction __user *, oact,
3668 compat_size_t, sigsetsize)
3670 struct k_sigaction new_ka, old_ka;
3671 #ifdef __ARCH_HAS_SA_RESTORER
3672 compat_uptr_t restorer;
3676 /* XXX: Don't preclude handling different sized sigset_t's. */
3677 if (sigsetsize != sizeof(compat_sigset_t))
3681 compat_uptr_t handler;
3682 ret = get_user(handler, &act->sa_handler);
3683 new_ka.sa.sa_handler = compat_ptr(handler);
3684 #ifdef __ARCH_HAS_SA_RESTORER
3685 ret |= get_user(restorer, &act->sa_restorer);
3686 new_ka.sa.sa_restorer = compat_ptr(restorer);
3688 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
3689 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3694 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3696 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3698 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
3699 sizeof(oact->sa_mask));
3700 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3701 #ifdef __ARCH_HAS_SA_RESTORER
3702 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3703 &oact->sa_restorer);
3709 #endif /* !CONFIG_ODD_RT_SIGACTION */
3711 #ifdef CONFIG_OLD_SIGACTION
3712 SYSCALL_DEFINE3(sigaction, int, sig,
3713 const struct old_sigaction __user *, act,
3714 struct old_sigaction __user *, oact)
3716 struct k_sigaction new_ka, old_ka;
3721 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3722 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3723 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3724 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3725 __get_user(mask, &act->sa_mask))
3727 #ifdef __ARCH_HAS_KA_RESTORER
3728 new_ka.ka_restorer = NULL;
3730 siginitset(&new_ka.sa.sa_mask, mask);
3733 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3736 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3737 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3738 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3739 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3740 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3747 #ifdef CONFIG_COMPAT_OLD_SIGACTION
3748 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3749 const struct compat_old_sigaction __user *, act,
3750 struct compat_old_sigaction __user *, oact)
3752 struct k_sigaction new_ka, old_ka;
3754 compat_old_sigset_t mask;
3755 compat_uptr_t handler, restorer;
3758 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3759 __get_user(handler, &act->sa_handler) ||
3760 __get_user(restorer, &act->sa_restorer) ||
3761 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3762 __get_user(mask, &act->sa_mask))
3765 #ifdef __ARCH_HAS_KA_RESTORER
3766 new_ka.ka_restorer = NULL;
3768 new_ka.sa.sa_handler = compat_ptr(handler);
3769 new_ka.sa.sa_restorer = compat_ptr(restorer);
3770 siginitset(&new_ka.sa.sa_mask, mask);
3773 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3776 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3777 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3778 &oact->sa_handler) ||
3779 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3780 &oact->sa_restorer) ||
3781 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3782 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3789 #ifdef CONFIG_SGETMASK_SYSCALL
3792 * For backwards compatibility. Functionality superseded by sigprocmask.
3794 SYSCALL_DEFINE0(sgetmask)
3797 return current->blocked.sig[0];
3800 SYSCALL_DEFINE1(ssetmask, int, newmask)
3802 int old = current->blocked.sig[0];
3805 siginitset(&newset, newmask);
3806 set_current_blocked(&newset);
3810 #endif /* CONFIG_SGETMASK_SYSCALL */
3812 #ifdef __ARCH_WANT_SYS_SIGNAL
3814 * For backwards compatibility. Functionality superseded by sigaction.
3816 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3818 struct k_sigaction new_sa, old_sa;
3821 new_sa.sa.sa_handler = handler;
3822 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3823 sigemptyset(&new_sa.sa.sa_mask);
3825 ret = do_sigaction(sig, &new_sa, &old_sa);
3827 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3829 #endif /* __ARCH_WANT_SYS_SIGNAL */
3831 #ifdef __ARCH_WANT_SYS_PAUSE
3833 SYSCALL_DEFINE0(pause)
3835 while (!signal_pending(current)) {
3836 __set_current_state(TASK_INTERRUPTIBLE);
3839 return -ERESTARTNOHAND;
3844 static int sigsuspend(sigset_t *set)
3846 current->saved_sigmask = current->blocked;
3847 set_current_blocked(set);
3849 while (!signal_pending(current)) {
3850 __set_current_state(TASK_INTERRUPTIBLE);
3853 set_restore_sigmask();
3854 return -ERESTARTNOHAND;
3858 * sys_rt_sigsuspend - replace the signal mask for a value with the
3859 * @unewset value until a signal is received
3860 * @unewset: new signal mask value
3861 * @sigsetsize: size of sigset_t type
3863 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3867 /* XXX: Don't preclude handling different sized sigset_t's. */
3868 if (sigsetsize != sizeof(sigset_t))
3871 if (copy_from_user(&newset, unewset, sizeof(newset)))
3873 return sigsuspend(&newset);
3876 #ifdef CONFIG_COMPAT
3877 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3881 /* XXX: Don't preclude handling different sized sigset_t's. */
3882 if (sigsetsize != sizeof(sigset_t))
3885 if (get_compat_sigset(&newset, unewset))
3887 return sigsuspend(&newset);
3891 #ifdef CONFIG_OLD_SIGSUSPEND
3892 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3895 siginitset(&blocked, mask);
3896 return sigsuspend(&blocked);
3899 #ifdef CONFIG_OLD_SIGSUSPEND3
3900 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3903 siginitset(&blocked, mask);
3904 return sigsuspend(&blocked);
3908 __weak const char *arch_vma_name(struct vm_area_struct *vma)
3913 void __init signals_init(void)
3915 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3916 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3917 != offsetof(struct siginfo, _sifields._pad));
3918 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
3920 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3923 #ifdef CONFIG_KGDB_KDB
3924 #include <linux/kdb.h>
3926 * kdb_send_sig - Allows kdb to send signals without exposing
3927 * signal internals. This function checks if the required locks are
3928 * available before calling the main signal code, to avoid kdb
3931 void kdb_send_sig(struct task_struct *t, int sig)
3933 static struct task_struct *kdb_prev_t;
3935 if (!spin_trylock(&t->sighand->siglock)) {
3936 kdb_printf("Can't do kill command now.\n"
3937 "The sigmask lock is held somewhere else in "
3938 "kernel, try again later\n");
3941 new_t = kdb_prev_t != t;
3943 if (t->state != TASK_RUNNING && new_t) {
3944 spin_unlock(&t->sighand->siglock);
3945 kdb_printf("Process is not RUNNING, sending a signal from "
3946 "kdb risks deadlock\n"
3947 "on the run queue locks. "
3948 "The signal has _not_ been sent.\n"
3949 "Reissue the kill command if you want to risk "
3953 ret = send_signal(sig, SEND_SIG_PRIV, t, false);
3954 spin_unlock(&t->sighand->siglock);
3956 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3959 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3961 #endif /* CONFIG_KGDB_KDB */