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/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/ratelimit.h>
26 #include <linux/tracehook.h>
27 #include <linux/capability.h>
28 #include <linux/freezer.h>
29 #include <linux/pid_namespace.h>
30 #include <linux/nsproxy.h>
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/signal.h>
34 #include <asm/param.h>
35 #include <asm/uaccess.h>
36 #include <asm/unistd.h>
37 #include <asm/siginfo.h>
38 #include "audit.h" /* audit_signal_info() */
41 * SLAB caches for signal bits.
44 static struct kmem_cache
*sigqueue_cachep
;
46 int print_fatal_signals __read_mostly
;
48 static void __user
*sig_handler(struct task_struct
*t
, int sig
)
50 return t
->sighand
->action
[sig
- 1].sa
.sa_handler
;
53 static int sig_handler_ignored(void __user
*handler
, int sig
)
55 /* Is it explicitly or implicitly ignored? */
56 return handler
== SIG_IGN
||
57 (handler
== SIG_DFL
&& sig_kernel_ignore(sig
));
60 static int sig_task_ignored(struct task_struct
*t
, int sig
,
65 handler
= sig_handler(t
, sig
);
67 if (unlikely(t
->signal
->flags
& SIGNAL_UNKILLABLE
) &&
68 handler
== SIG_DFL
&& !from_ancestor_ns
)
71 return sig_handler_ignored(handler
, sig
);
74 static int sig_ignored(struct task_struct
*t
, int sig
, int from_ancestor_ns
)
77 * Blocked signals are never ignored, since the
78 * signal handler may change by the time it is
81 if (sigismember(&t
->blocked
, sig
) || sigismember(&t
->real_blocked
, sig
))
84 if (!sig_task_ignored(t
, sig
, from_ancestor_ns
))
88 * Tracers may want to know about even ignored signals.
94 * Re-calculate pending state from the set of locally pending
95 * signals, globally pending signals, and blocked signals.
97 static inline int has_pending_signals(sigset_t
*signal
, sigset_t
*blocked
)
102 switch (_NSIG_WORDS
) {
104 for (i
= _NSIG_WORDS
, ready
= 0; --i
>= 0 ;)
105 ready
|= signal
->sig
[i
] &~ blocked
->sig
[i
];
108 case 4: ready
= signal
->sig
[3] &~ blocked
->sig
[3];
109 ready
|= signal
->sig
[2] &~ blocked
->sig
[2];
110 ready
|= signal
->sig
[1] &~ blocked
->sig
[1];
111 ready
|= signal
->sig
[0] &~ blocked
->sig
[0];
114 case 2: ready
= signal
->sig
[1] &~ blocked
->sig
[1];
115 ready
|= signal
->sig
[0] &~ blocked
->sig
[0];
118 case 1: ready
= signal
->sig
[0] &~ blocked
->sig
[0];
123 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
125 static int recalc_sigpending_tsk(struct task_struct
*t
)
127 if ((t
->jobctl
& JOBCTL_PENDING_MASK
) ||
128 PENDING(&t
->pending
, &t
->blocked
) ||
129 PENDING(&t
->signal
->shared_pending
, &t
->blocked
)) {
130 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
134 * We must never clear the flag in another thread, or in current
135 * when it's possible the current syscall is returning -ERESTART*.
136 * So we don't clear it here, and only callers who know they should do.
142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
143 * This is superfluous when called on current, the wakeup is a harmless no-op.
145 void recalc_sigpending_and_wake(struct task_struct
*t
)
147 if (recalc_sigpending_tsk(t
))
148 signal_wake_up(t
, 0);
151 void recalc_sigpending(void)
153 if (!recalc_sigpending_tsk(current
) && !freezing(current
))
154 clear_thread_flag(TIF_SIGPENDING
);
158 /* Given the mask, find the first available signal that should be serviced. */
160 #define SYNCHRONOUS_MASK \
161 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
162 sigmask(SIGTRAP) | sigmask(SIGFPE))
164 int next_signal(struct sigpending
*pending
, sigset_t
*mask
)
166 unsigned long i
, *s
, *m
, x
;
169 s
= pending
->signal
.sig
;
173 * Handle the first word specially: it contains the
174 * synchronous signals that need to be dequeued first.
178 if (x
& SYNCHRONOUS_MASK
)
179 x
&= SYNCHRONOUS_MASK
;
184 switch (_NSIG_WORDS
) {
186 for (i
= 1; i
< _NSIG_WORDS
; ++i
) {
190 sig
= ffz(~x
) + i
*_NSIG_BPW
+ 1;
199 sig
= ffz(~x
) + _NSIG_BPW
+ 1;
210 static inline void print_dropped_signal(int sig
)
212 static DEFINE_RATELIMIT_STATE(ratelimit_state
, 5 * HZ
, 10);
214 if (!print_fatal_signals
)
217 if (!__ratelimit(&ratelimit_state
))
220 printk(KERN_INFO
"%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
221 current
->comm
, current
->pid
, sig
);
225 * task_set_jobctl_pending - set jobctl pending bits
227 * @mask: pending bits to set
229 * Clear @mask from @task->jobctl. @mask must be subset of
230 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
231 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
232 * cleared. If @task is already being killed or exiting, this function
236 * Must be called with @task->sighand->siglock held.
239 * %true if @mask is set, %false if made noop because @task was dying.
241 bool task_set_jobctl_pending(struct task_struct
*task
, unsigned int mask
)
243 BUG_ON(mask
& ~(JOBCTL_PENDING_MASK
| JOBCTL_STOP_CONSUME
|
244 JOBCTL_STOP_SIGMASK
| JOBCTL_TRAPPING
));
245 BUG_ON((mask
& JOBCTL_TRAPPING
) && !(mask
& JOBCTL_PENDING_MASK
));
247 if (unlikely(fatal_signal_pending(task
) || (task
->flags
& PF_EXITING
)))
250 if (mask
& JOBCTL_STOP_SIGMASK
)
251 task
->jobctl
&= ~JOBCTL_STOP_SIGMASK
;
253 task
->jobctl
|= mask
;
258 * task_clear_jobctl_trapping - clear jobctl trapping bit
261 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
262 * Clear it and wake up the ptracer. Note that we don't need any further
263 * locking. @task->siglock guarantees that @task->parent points to the
267 * Must be called with @task->sighand->siglock held.
269 void task_clear_jobctl_trapping(struct task_struct
*task
)
271 if (unlikely(task
->jobctl
& JOBCTL_TRAPPING
)) {
272 task
->jobctl
&= ~JOBCTL_TRAPPING
;
273 wake_up_bit(&task
->jobctl
, JOBCTL_TRAPPING_BIT
);
278 * task_clear_jobctl_pending - clear jobctl pending bits
280 * @mask: pending bits to clear
282 * Clear @mask from @task->jobctl. @mask must be subset of
283 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
284 * STOP bits are cleared together.
286 * If clearing of @mask leaves no stop or trap pending, this function calls
287 * task_clear_jobctl_trapping().
290 * Must be called with @task->sighand->siglock held.
292 void task_clear_jobctl_pending(struct task_struct
*task
, unsigned int mask
)
294 BUG_ON(mask
& ~JOBCTL_PENDING_MASK
);
296 if (mask
& JOBCTL_STOP_PENDING
)
297 mask
|= JOBCTL_STOP_CONSUME
| JOBCTL_STOP_DEQUEUED
;
299 task
->jobctl
&= ~mask
;
301 if (!(task
->jobctl
& JOBCTL_PENDING_MASK
))
302 task_clear_jobctl_trapping(task
);
306 * task_participate_group_stop - participate in a group stop
307 * @task: task participating in a group stop
309 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
310 * Group stop states are cleared and the group stop count is consumed if
311 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
312 * stop, the appropriate %SIGNAL_* flags are set.
315 * Must be called with @task->sighand->siglock held.
318 * %true if group stop completion should be notified to the parent, %false
321 static bool task_participate_group_stop(struct task_struct
*task
)
323 struct signal_struct
*sig
= task
->signal
;
324 bool consume
= task
->jobctl
& JOBCTL_STOP_CONSUME
;
326 WARN_ON_ONCE(!(task
->jobctl
& JOBCTL_STOP_PENDING
));
328 task_clear_jobctl_pending(task
, JOBCTL_STOP_PENDING
);
333 if (!WARN_ON_ONCE(sig
->group_stop_count
== 0))
334 sig
->group_stop_count
--;
337 * Tell the caller to notify completion iff we are entering into a
338 * fresh group stop. Read comment in do_signal_stop() for details.
340 if (!sig
->group_stop_count
&& !(sig
->flags
& SIGNAL_STOP_STOPPED
)) {
341 sig
->flags
= SIGNAL_STOP_STOPPED
;
348 * allocate a new signal queue record
349 * - this may be called without locks if and only if t == current, otherwise an
350 * appropriate lock must be held to stop the target task from exiting
352 static struct sigqueue
*
353 __sigqueue_alloc(int sig
, struct task_struct
*t
, gfp_t flags
, int override_rlimit
)
355 struct sigqueue
*q
= NULL
;
356 struct user_struct
*user
;
359 * Protect access to @t credentials. This can go away when all
360 * callers hold rcu read lock.
363 user
= get_uid(__task_cred(t
)->user
);
364 atomic_inc(&user
->sigpending
);
367 if (override_rlimit
||
368 atomic_read(&user
->sigpending
) <=
369 task_rlimit(t
, RLIMIT_SIGPENDING
)) {
370 q
= kmem_cache_alloc(sigqueue_cachep
, flags
);
372 print_dropped_signal(sig
);
375 if (unlikely(q
== NULL
)) {
376 atomic_dec(&user
->sigpending
);
379 INIT_LIST_HEAD(&q
->list
);
387 static void __sigqueue_free(struct sigqueue
*q
)
389 if (q
->flags
& SIGQUEUE_PREALLOC
)
391 atomic_dec(&q
->user
->sigpending
);
393 kmem_cache_free(sigqueue_cachep
, q
);
396 void flush_sigqueue(struct sigpending
*queue
)
400 sigemptyset(&queue
->signal
);
401 while (!list_empty(&queue
->list
)) {
402 q
= list_entry(queue
->list
.next
, struct sigqueue
, list
);
403 list_del_init(&q
->list
);
409 * Flush all pending signals for a task.
411 void __flush_signals(struct task_struct
*t
)
413 clear_tsk_thread_flag(t
, TIF_SIGPENDING
);
414 flush_sigqueue(&t
->pending
);
415 flush_sigqueue(&t
->signal
->shared_pending
);
418 void flush_signals(struct task_struct
*t
)
422 spin_lock_irqsave(&t
->sighand
->siglock
, flags
);
424 spin_unlock_irqrestore(&t
->sighand
->siglock
, flags
);
427 static void __flush_itimer_signals(struct sigpending
*pending
)
429 sigset_t signal
, retain
;
430 struct sigqueue
*q
, *n
;
432 signal
= pending
->signal
;
433 sigemptyset(&retain
);
435 list_for_each_entry_safe(q
, n
, &pending
->list
, list
) {
436 int sig
= q
->info
.si_signo
;
438 if (likely(q
->info
.si_code
!= SI_TIMER
)) {
439 sigaddset(&retain
, sig
);
441 sigdelset(&signal
, sig
);
442 list_del_init(&q
->list
);
447 sigorsets(&pending
->signal
, &signal
, &retain
);
450 void flush_itimer_signals(void)
452 struct task_struct
*tsk
= current
;
455 spin_lock_irqsave(&tsk
->sighand
->siglock
, flags
);
456 __flush_itimer_signals(&tsk
->pending
);
457 __flush_itimer_signals(&tsk
->signal
->shared_pending
);
458 spin_unlock_irqrestore(&tsk
->sighand
->siglock
, flags
);
461 void ignore_signals(struct task_struct
*t
)
465 for (i
= 0; i
< _NSIG
; ++i
)
466 t
->sighand
->action
[i
].sa
.sa_handler
= SIG_IGN
;
472 * Flush all handlers for a task.
476 flush_signal_handlers(struct task_struct
*t
, int force_default
)
479 struct k_sigaction
*ka
= &t
->sighand
->action
[0];
480 for (i
= _NSIG
; i
!= 0 ; i
--) {
481 if (force_default
|| ka
->sa
.sa_handler
!= SIG_IGN
)
482 ka
->sa
.sa_handler
= SIG_DFL
;
484 sigemptyset(&ka
->sa
.sa_mask
);
489 int unhandled_signal(struct task_struct
*tsk
, int sig
)
491 void __user
*handler
= tsk
->sighand
->action
[sig
-1].sa
.sa_handler
;
492 if (is_global_init(tsk
))
494 if (handler
!= SIG_IGN
&& handler
!= SIG_DFL
)
496 /* if ptraced, let the tracer determine */
501 * Notify the system that a driver wants to block all signals for this
502 * process, and wants to be notified if any signals at all were to be
503 * sent/acted upon. If the notifier routine returns non-zero, then the
504 * signal will be acted upon after all. If the notifier routine returns 0,
505 * then then signal will be blocked. Only one block per process is
506 * allowed. priv is a pointer to private data that the notifier routine
507 * can use to determine if the signal should be blocked or not.
510 block_all_signals(int (*notifier
)(void *priv
), void *priv
, sigset_t
*mask
)
514 spin_lock_irqsave(¤t
->sighand
->siglock
, flags
);
515 current
->notifier_mask
= mask
;
516 current
->notifier_data
= priv
;
517 current
->notifier
= notifier
;
518 spin_unlock_irqrestore(¤t
->sighand
->siglock
, flags
);
521 /* Notify the system that blocking has ended. */
524 unblock_all_signals(void)
528 spin_lock_irqsave(¤t
->sighand
->siglock
, flags
);
529 current
->notifier
= NULL
;
530 current
->notifier_data
= NULL
;
532 spin_unlock_irqrestore(¤t
->sighand
->siglock
, flags
);
535 static void collect_signal(int sig
, struct sigpending
*list
, siginfo_t
*info
)
537 struct sigqueue
*q
, *first
= NULL
;
540 * Collect the siginfo appropriate to this signal. Check if
541 * there is another siginfo for the same signal.
543 list_for_each_entry(q
, &list
->list
, list
) {
544 if (q
->info
.si_signo
== sig
) {
551 sigdelset(&list
->signal
, sig
);
555 list_del_init(&first
->list
);
556 copy_siginfo(info
, &first
->info
);
557 __sigqueue_free(first
);
560 * Ok, it wasn't in the queue. This must be
561 * a fast-pathed signal or we must have been
562 * out of queue space. So zero out the info.
564 info
->si_signo
= sig
;
566 info
->si_code
= SI_USER
;
572 static int __dequeue_signal(struct sigpending
*pending
, sigset_t
*mask
,
575 int sig
= next_signal(pending
, mask
);
578 if (current
->notifier
) {
579 if (sigismember(current
->notifier_mask
, sig
)) {
580 if (!(current
->notifier
)(current
->notifier_data
)) {
581 clear_thread_flag(TIF_SIGPENDING
);
587 collect_signal(sig
, pending
, info
);
594 * Dequeue a signal and return the element to the caller, which is
595 * expected to free it.
597 * All callers have to hold the siglock.
599 int dequeue_signal(struct task_struct
*tsk
, sigset_t
*mask
, siginfo_t
*info
)
603 /* We only dequeue private signals from ourselves, we don't let
604 * signalfd steal them
606 signr
= __dequeue_signal(&tsk
->pending
, mask
, info
);
608 signr
= __dequeue_signal(&tsk
->signal
->shared_pending
,
613 * itimers are process shared and we restart periodic
614 * itimers in the signal delivery path to prevent DoS
615 * attacks in the high resolution timer case. This is
616 * compliant with the old way of self-restarting
617 * itimers, as the SIGALRM is a legacy signal and only
618 * queued once. Changing the restart behaviour to
619 * restart the timer in the signal dequeue path is
620 * reducing the timer noise on heavy loaded !highres
623 if (unlikely(signr
== SIGALRM
)) {
624 struct hrtimer
*tmr
= &tsk
->signal
->real_timer
;
626 if (!hrtimer_is_queued(tmr
) &&
627 tsk
->signal
->it_real_incr
.tv64
!= 0) {
628 hrtimer_forward(tmr
, tmr
->base
->get_time(),
629 tsk
->signal
->it_real_incr
);
630 hrtimer_restart(tmr
);
639 if (unlikely(sig_kernel_stop(signr
))) {
641 * Set a marker that we have dequeued a stop signal. Our
642 * caller might release the siglock and then the pending
643 * stop signal it is about to process is no longer in the
644 * pending bitmasks, but must still be cleared by a SIGCONT
645 * (and overruled by a SIGKILL). So those cases clear this
646 * shared flag after we've set it. Note that this flag may
647 * remain set after the signal we return is ignored or
648 * handled. That doesn't matter because its only purpose
649 * is to alert stop-signal processing code when another
650 * processor has come along and cleared the flag.
652 current
->jobctl
|= JOBCTL_STOP_DEQUEUED
;
654 if ((info
->si_code
& __SI_MASK
) == __SI_TIMER
&& info
->si_sys_private
) {
656 * Release the siglock to ensure proper locking order
657 * of timer locks outside of siglocks. Note, we leave
658 * irqs disabled here, since the posix-timers code is
659 * about to disable them again anyway.
661 spin_unlock(&tsk
->sighand
->siglock
);
662 do_schedule_next_timer(info
);
663 spin_lock(&tsk
->sighand
->siglock
);
669 * Tell a process that it has a new active signal..
671 * NOTE! we rely on the previous spin_lock to
672 * lock interrupts for us! We can only be called with
673 * "siglock" held, and the local interrupt must
674 * have been disabled when that got acquired!
676 * No need to set need_resched since signal event passing
677 * goes through ->blocked
679 void signal_wake_up(struct task_struct
*t
, int resume
)
683 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
686 * For SIGKILL, we want to wake it up in the stopped/traced/killable
687 * case. We don't check t->state here because there is a race with it
688 * executing another processor and just now entering stopped state.
689 * By using wake_up_state, we ensure the process will wake up and
690 * handle its death signal.
692 mask
= TASK_INTERRUPTIBLE
;
694 mask
|= TASK_WAKEKILL
;
695 if (!wake_up_state(t
, mask
))
700 * Remove signals in mask from the pending set and queue.
701 * Returns 1 if any signals were found.
703 * All callers must be holding the siglock.
705 * This version takes a sigset mask and looks at all signals,
706 * not just those in the first mask word.
708 static int rm_from_queue_full(sigset_t
*mask
, struct sigpending
*s
)
710 struct sigqueue
*q
, *n
;
713 sigandsets(&m
, mask
, &s
->signal
);
714 if (sigisemptyset(&m
))
717 sigandnsets(&s
->signal
, &s
->signal
, mask
);
718 list_for_each_entry_safe(q
, n
, &s
->list
, list
) {
719 if (sigismember(mask
, q
->info
.si_signo
)) {
720 list_del_init(&q
->list
);
727 * Remove signals in mask from the pending set and queue.
728 * Returns 1 if any signals were found.
730 * All callers must be holding the siglock.
732 static int rm_from_queue(unsigned long mask
, struct sigpending
*s
)
734 struct sigqueue
*q
, *n
;
736 if (!sigtestsetmask(&s
->signal
, mask
))
739 sigdelsetmask(&s
->signal
, mask
);
740 list_for_each_entry_safe(q
, n
, &s
->list
, list
) {
741 if (q
->info
.si_signo
< SIGRTMIN
&&
742 (mask
& sigmask(q
->info
.si_signo
))) {
743 list_del_init(&q
->list
);
750 static inline int is_si_special(const struct siginfo
*info
)
752 return info
<= SEND_SIG_FORCED
;
755 static inline bool si_fromuser(const struct siginfo
*info
)
757 return info
== SEND_SIG_NOINFO
||
758 (!is_si_special(info
) && SI_FROMUSER(info
));
762 * called with RCU read lock from check_kill_permission()
764 static int kill_ok_by_cred(struct task_struct
*t
)
766 const struct cred
*cred
= current_cred();
767 const struct cred
*tcred
= __task_cred(t
);
769 if (cred
->user
->user_ns
== tcred
->user
->user_ns
&&
770 (cred
->euid
== tcred
->suid
||
771 cred
->euid
== tcred
->uid
||
772 cred
->uid
== tcred
->suid
||
773 cred
->uid
== tcred
->uid
))
776 if (ns_capable(tcred
->user
->user_ns
, CAP_KILL
))
783 * Bad permissions for sending the signal
784 * - the caller must hold the RCU read lock
786 static int check_kill_permission(int sig
, struct siginfo
*info
,
787 struct task_struct
*t
)
792 if (!valid_signal(sig
))
795 if (!si_fromuser(info
))
798 error
= audit_signal_info(sig
, t
); /* Let audit system see the signal */
802 if (!same_thread_group(current
, t
) &&
803 !kill_ok_by_cred(t
)) {
806 sid
= task_session(t
);
808 * We don't return the error if sid == NULL. The
809 * task was unhashed, the caller must notice this.
811 if (!sid
|| sid
== task_session(current
))
818 return security_task_kill(t
, info
, sig
, 0);
822 * ptrace_trap_notify - schedule trap to notify ptracer
823 * @t: tracee wanting to notify tracer
825 * This function schedules sticky ptrace trap which is cleared on the next
826 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
829 * If @t is running, STOP trap will be taken. If trapped for STOP and
830 * ptracer is listening for events, tracee is woken up so that it can
831 * re-trap for the new event. If trapped otherwise, STOP trap will be
832 * eventually taken without returning to userland after the existing traps
833 * are finished by PTRACE_CONT.
836 * Must be called with @task->sighand->siglock held.
838 static void ptrace_trap_notify(struct task_struct
*t
)
840 WARN_ON_ONCE(!(t
->ptrace
& PT_SEIZED
));
841 assert_spin_locked(&t
->sighand
->siglock
);
843 task_set_jobctl_pending(t
, JOBCTL_TRAP_NOTIFY
);
844 signal_wake_up(t
, t
->jobctl
& JOBCTL_LISTENING
);
848 * Handle magic process-wide effects of stop/continue signals. Unlike
849 * the signal actions, these happen immediately at signal-generation
850 * time regardless of blocking, ignoring, or handling. This does the
851 * actual continuing for SIGCONT, but not the actual stopping for stop
852 * signals. The process stop is done as a signal action for SIG_DFL.
854 * Returns true if the signal should be actually delivered, otherwise
855 * it should be dropped.
857 static int prepare_signal(int sig
, struct task_struct
*p
, int from_ancestor_ns
)
859 struct signal_struct
*signal
= p
->signal
;
860 struct task_struct
*t
;
862 if (unlikely(signal
->flags
& SIGNAL_GROUP_EXIT
)) {
864 * The process is in the middle of dying, nothing to do.
866 } else if (sig_kernel_stop(sig
)) {
868 * This is a stop signal. Remove SIGCONT from all queues.
870 rm_from_queue(sigmask(SIGCONT
), &signal
->shared_pending
);
873 rm_from_queue(sigmask(SIGCONT
), &t
->pending
);
874 } while_each_thread(p
, t
);
875 } else if (sig
== SIGCONT
) {
878 * Remove all stop signals from all queues, wake all threads.
880 rm_from_queue(SIG_KERNEL_STOP_MASK
, &signal
->shared_pending
);
883 task_clear_jobctl_pending(t
, JOBCTL_STOP_PENDING
);
884 rm_from_queue(SIG_KERNEL_STOP_MASK
, &t
->pending
);
885 if (likely(!(t
->ptrace
& PT_SEIZED
)))
886 wake_up_state(t
, __TASK_STOPPED
);
888 ptrace_trap_notify(t
);
889 } while_each_thread(p
, t
);
892 * Notify the parent with CLD_CONTINUED if we were stopped.
894 * If we were in the middle of a group stop, we pretend it
895 * was already finished, and then continued. Since SIGCHLD
896 * doesn't queue we report only CLD_STOPPED, as if the next
897 * CLD_CONTINUED was dropped.
900 if (signal
->flags
& SIGNAL_STOP_STOPPED
)
901 why
|= SIGNAL_CLD_CONTINUED
;
902 else if (signal
->group_stop_count
)
903 why
|= SIGNAL_CLD_STOPPED
;
907 * The first thread which returns from do_signal_stop()
908 * will take ->siglock, notice SIGNAL_CLD_MASK, and
909 * notify its parent. See get_signal_to_deliver().
911 signal
->flags
= why
| SIGNAL_STOP_CONTINUED
;
912 signal
->group_stop_count
= 0;
913 signal
->group_exit_code
= 0;
917 return !sig_ignored(p
, sig
, from_ancestor_ns
);
921 * Test if P wants to take SIG. After we've checked all threads with this,
922 * it's equivalent to finding no threads not blocking SIG. Any threads not
923 * blocking SIG were ruled out because they are not running and already
924 * have pending signals. Such threads will dequeue from the shared queue
925 * as soon as they're available, so putting the signal on the shared queue
926 * will be equivalent to sending it to one such thread.
928 static inline int wants_signal(int sig
, struct task_struct
*p
)
930 if (sigismember(&p
->blocked
, sig
))
932 if (p
->flags
& PF_EXITING
)
936 if (task_is_stopped_or_traced(p
))
938 return task_curr(p
) || !signal_pending(p
);
941 static void complete_signal(int sig
, struct task_struct
*p
, int group
)
943 struct signal_struct
*signal
= p
->signal
;
944 struct task_struct
*t
;
947 * Now find a thread we can wake up to take the signal off the queue.
949 * If the main thread wants the signal, it gets first crack.
950 * Probably the least surprising to the average bear.
952 if (wants_signal(sig
, p
))
954 else if (!group
|| thread_group_empty(p
))
956 * There is just one thread and it does not need to be woken.
957 * It will dequeue unblocked signals before it runs again.
962 * Otherwise try to find a suitable thread.
964 t
= signal
->curr_target
;
965 while (!wants_signal(sig
, t
)) {
967 if (t
== signal
->curr_target
)
969 * No thread needs to be woken.
970 * Any eligible threads will see
971 * the signal in the queue soon.
975 signal
->curr_target
= t
;
979 * Found a killable thread. If the signal will be fatal,
980 * then start taking the whole group down immediately.
982 if (sig_fatal(p
, sig
) &&
983 !(signal
->flags
& (SIGNAL_UNKILLABLE
| SIGNAL_GROUP_EXIT
)) &&
984 !sigismember(&t
->real_blocked
, sig
) &&
985 (sig
== SIGKILL
|| !t
->ptrace
)) {
987 * This signal will be fatal to the whole group.
989 if (!sig_kernel_coredump(sig
)) {
991 * Start a group exit and wake everybody up.
992 * This way we don't have other threads
993 * running and doing things after a slower
994 * thread has the fatal signal pending.
996 signal
->flags
= SIGNAL_GROUP_EXIT
;
997 signal
->group_exit_code
= sig
;
998 signal
->group_stop_count
= 0;
1001 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
1002 sigaddset(&t
->pending
.signal
, SIGKILL
);
1003 signal_wake_up(t
, 1);
1004 } while_each_thread(p
, t
);
1010 * The signal is already in the shared-pending queue.
1011 * Tell the chosen thread to wake up and dequeue it.
1013 signal_wake_up(t
, sig
== SIGKILL
);
1017 static inline int legacy_queue(struct sigpending
*signals
, int sig
)
1019 return (sig
< SIGRTMIN
) && sigismember(&signals
->signal
, sig
);
1022 static int __send_signal(int sig
, struct siginfo
*info
, struct task_struct
*t
,
1023 int group
, int from_ancestor_ns
)
1025 struct sigpending
*pending
;
1027 int override_rlimit
;
1029 trace_signal_generate(sig
, info
, t
);
1031 assert_spin_locked(&t
->sighand
->siglock
);
1033 if (!prepare_signal(sig
, t
, from_ancestor_ns
))
1036 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
1038 * Short-circuit ignored signals and support queuing
1039 * exactly one non-rt signal, so that we can get more
1040 * detailed information about the cause of the signal.
1042 if (legacy_queue(pending
, sig
))
1045 * fast-pathed signals for kernel-internal things like SIGSTOP
1048 if (info
== SEND_SIG_FORCED
)
1052 * Real-time signals must be queued if sent by sigqueue, or
1053 * some other real-time mechanism. It is implementation
1054 * defined whether kill() does so. We attempt to do so, on
1055 * the principle of least surprise, but since kill is not
1056 * allowed to fail with EAGAIN when low on memory we just
1057 * make sure at least one signal gets delivered and don't
1058 * pass on the info struct.
1061 override_rlimit
= (is_si_special(info
) || info
->si_code
>= 0);
1063 override_rlimit
= 0;
1065 q
= __sigqueue_alloc(sig
, t
, GFP_ATOMIC
| __GFP_NOTRACK_FALSE_POSITIVE
,
1068 list_add_tail(&q
->list
, &pending
->list
);
1069 switch ((unsigned long) info
) {
1070 case (unsigned long) SEND_SIG_NOINFO
:
1071 q
->info
.si_signo
= sig
;
1072 q
->info
.si_errno
= 0;
1073 q
->info
.si_code
= SI_USER
;
1074 q
->info
.si_pid
= task_tgid_nr_ns(current
,
1075 task_active_pid_ns(t
));
1076 q
->info
.si_uid
= current_uid();
1078 case (unsigned long) SEND_SIG_PRIV
:
1079 q
->info
.si_signo
= sig
;
1080 q
->info
.si_errno
= 0;
1081 q
->info
.si_code
= SI_KERNEL
;
1086 copy_siginfo(&q
->info
, info
);
1087 if (from_ancestor_ns
)
1091 } else if (!is_si_special(info
)) {
1092 if (sig
>= SIGRTMIN
&& info
->si_code
!= SI_USER
) {
1094 * Queue overflow, abort. We may abort if the
1095 * signal was rt and sent by user using something
1096 * other than kill().
1098 trace_signal_overflow_fail(sig
, group
, info
);
1102 * This is a silent loss of information. We still
1103 * send the signal, but the *info bits are lost.
1105 trace_signal_lose_info(sig
, group
, info
);
1110 signalfd_notify(t
, sig
);
1111 sigaddset(&pending
->signal
, sig
);
1112 complete_signal(sig
, t
, group
);
1116 static int send_signal(int sig
, struct siginfo
*info
, struct task_struct
*t
,
1119 int from_ancestor_ns
= 0;
1121 #ifdef CONFIG_PID_NS
1122 from_ancestor_ns
= si_fromuser(info
) &&
1123 !task_pid_nr_ns(current
, task_active_pid_ns(t
));
1126 return __send_signal(sig
, info
, t
, group
, from_ancestor_ns
);
1129 static void print_fatal_signal(struct pt_regs
*regs
, int signr
)
1131 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1132 current
->comm
, task_pid_nr(current
), signr
);
1134 #if defined(__i386__) && !defined(__arch_um__)
1135 printk("code at %08lx: ", regs
->ip
);
1138 for (i
= 0; i
< 16; i
++) {
1141 if (get_user(insn
, (unsigned char *)(regs
->ip
+ i
)))
1143 printk("%02x ", insn
);
1153 static int __init
setup_print_fatal_signals(char *str
)
1155 get_option (&str
, &print_fatal_signals
);
1160 __setup("print-fatal-signals=", setup_print_fatal_signals
);
1163 __group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1165 return send_signal(sig
, info
, p
, 1);
1169 specific_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
1171 return send_signal(sig
, info
, t
, 0);
1174 int do_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
,
1177 unsigned long flags
;
1180 if (lock_task_sighand(p
, &flags
)) {
1181 ret
= send_signal(sig
, info
, p
, group
);
1182 unlock_task_sighand(p
, &flags
);
1189 * Force a signal that the process can't ignore: if necessary
1190 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1192 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1193 * since we do not want to have a signal handler that was blocked
1194 * be invoked when user space had explicitly blocked it.
1196 * We don't want to have recursive SIGSEGV's etc, for example,
1197 * that is why we also clear SIGNAL_UNKILLABLE.
1200 force_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
1202 unsigned long int flags
;
1203 int ret
, blocked
, ignored
;
1204 struct k_sigaction
*action
;
1206 spin_lock_irqsave(&t
->sighand
->siglock
, flags
);
1207 action
= &t
->sighand
->action
[sig
-1];
1208 ignored
= action
->sa
.sa_handler
== SIG_IGN
;
1209 blocked
= sigismember(&t
->blocked
, sig
);
1210 if (blocked
|| ignored
) {
1211 action
->sa
.sa_handler
= SIG_DFL
;
1213 sigdelset(&t
->blocked
, sig
);
1214 recalc_sigpending_and_wake(t
);
1217 if (action
->sa
.sa_handler
== SIG_DFL
)
1218 t
->signal
->flags
&= ~SIGNAL_UNKILLABLE
;
1219 ret
= specific_send_sig_info(sig
, info
, t
);
1220 spin_unlock_irqrestore(&t
->sighand
->siglock
, flags
);
1226 * Nuke all other threads in the group.
1228 int zap_other_threads(struct task_struct
*p
)
1230 struct task_struct
*t
= p
;
1233 p
->signal
->group_stop_count
= 0;
1235 while_each_thread(p
, t
) {
1236 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
1239 /* Don't bother with already dead threads */
1242 sigaddset(&t
->pending
.signal
, SIGKILL
);
1243 signal_wake_up(t
, 1);
1249 struct sighand_struct
*__lock_task_sighand(struct task_struct
*tsk
,
1250 unsigned long *flags
)
1252 struct sighand_struct
*sighand
;
1256 sighand
= rcu_dereference(tsk
->sighand
);
1257 if (unlikely(sighand
== NULL
))
1260 spin_lock_irqsave(&sighand
->siglock
, *flags
);
1261 if (likely(sighand
== tsk
->sighand
))
1263 spin_unlock_irqrestore(&sighand
->siglock
, *flags
);
1271 * send signal info to all the members of a group
1273 int group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1278 ret
= check_kill_permission(sig
, info
, p
);
1282 ret
= do_send_sig_info(sig
, info
, p
, true);
1288 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1289 * control characters do (^C, ^Z etc)
1290 * - the caller must hold at least a readlock on tasklist_lock
1292 int __kill_pgrp_info(int sig
, struct siginfo
*info
, struct pid
*pgrp
)
1294 struct task_struct
*p
= NULL
;
1295 int retval
, success
;
1299 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
1300 int err
= group_send_sig_info(sig
, info
, p
);
1303 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
1304 return success
? 0 : retval
;
1307 int kill_pid_info(int sig
, struct siginfo
*info
, struct pid
*pid
)
1310 struct task_struct
*p
;
1314 p
= pid_task(pid
, PIDTYPE_PID
);
1316 error
= group_send_sig_info(sig
, info
, p
);
1317 if (unlikely(error
== -ESRCH
))
1319 * The task was unhashed in between, try again.
1320 * If it is dead, pid_task() will return NULL,
1321 * if we race with de_thread() it will find the
1331 int kill_proc_info(int sig
, struct siginfo
*info
, pid_t pid
)
1335 error
= kill_pid_info(sig
, info
, find_vpid(pid
));
1340 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1341 int kill_pid_info_as_uid(int sig
, struct siginfo
*info
, struct pid
*pid
,
1342 uid_t uid
, uid_t euid
, u32 secid
)
1345 struct task_struct
*p
;
1346 const struct cred
*pcred
;
1347 unsigned long flags
;
1349 if (!valid_signal(sig
))
1353 p
= pid_task(pid
, PIDTYPE_PID
);
1358 pcred
= __task_cred(p
);
1359 if (si_fromuser(info
) &&
1360 euid
!= pcred
->suid
&& euid
!= pcred
->uid
&&
1361 uid
!= pcred
->suid
&& uid
!= pcred
->uid
) {
1365 ret
= security_task_kill(p
, info
, sig
, secid
);
1370 if (lock_task_sighand(p
, &flags
)) {
1371 ret
= __send_signal(sig
, info
, p
, 1, 0);
1372 unlock_task_sighand(p
, &flags
);
1380 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid
);
1383 * kill_something_info() interprets pid in interesting ways just like kill(2).
1385 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1386 * is probably wrong. Should make it like BSD or SYSV.
1389 static int kill_something_info(int sig
, struct siginfo
*info
, pid_t pid
)
1395 ret
= kill_pid_info(sig
, info
, find_vpid(pid
));
1400 read_lock(&tasklist_lock
);
1402 ret
= __kill_pgrp_info(sig
, info
,
1403 pid
? find_vpid(-pid
) : task_pgrp(current
));
1405 int retval
= 0, count
= 0;
1406 struct task_struct
* p
;
1408 for_each_process(p
) {
1409 if (task_pid_vnr(p
) > 1 &&
1410 !same_thread_group(p
, current
)) {
1411 int err
= group_send_sig_info(sig
, info
, p
);
1417 ret
= count
? retval
: -ESRCH
;
1419 read_unlock(&tasklist_lock
);
1425 * These are for backward compatibility with the rest of the kernel source.
1428 int send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1431 * Make sure legacy kernel users don't send in bad values
1432 * (normal paths check this in check_kill_permission).
1434 if (!valid_signal(sig
))
1437 return do_send_sig_info(sig
, info
, p
, false);
1440 #define __si_special(priv) \
1441 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1444 send_sig(int sig
, struct task_struct
*p
, int priv
)
1446 return send_sig_info(sig
, __si_special(priv
), p
);
1450 force_sig(int sig
, struct task_struct
*p
)
1452 force_sig_info(sig
, SEND_SIG_PRIV
, p
);
1456 * When things go south during signal handling, we
1457 * will force a SIGSEGV. And if the signal that caused
1458 * the problem was already a SIGSEGV, we'll want to
1459 * make sure we don't even try to deliver the signal..
1462 force_sigsegv(int sig
, struct task_struct
*p
)
1464 if (sig
== SIGSEGV
) {
1465 unsigned long flags
;
1466 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1467 p
->sighand
->action
[sig
- 1].sa
.sa_handler
= SIG_DFL
;
1468 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1470 force_sig(SIGSEGV
, p
);
1474 int kill_pgrp(struct pid
*pid
, int sig
, int priv
)
1478 read_lock(&tasklist_lock
);
1479 ret
= __kill_pgrp_info(sig
, __si_special(priv
), pid
);
1480 read_unlock(&tasklist_lock
);
1484 EXPORT_SYMBOL(kill_pgrp
);
1486 int kill_pid(struct pid
*pid
, int sig
, int priv
)
1488 return kill_pid_info(sig
, __si_special(priv
), pid
);
1490 EXPORT_SYMBOL(kill_pid
);
1493 * These functions support sending signals using preallocated sigqueue
1494 * structures. This is needed "because realtime applications cannot
1495 * afford to lose notifications of asynchronous events, like timer
1496 * expirations or I/O completions". In the case of POSIX Timers
1497 * we allocate the sigqueue structure from the timer_create. If this
1498 * allocation fails we are able to report the failure to the application
1499 * with an EAGAIN error.
1501 struct sigqueue
*sigqueue_alloc(void)
1503 struct sigqueue
*q
= __sigqueue_alloc(-1, current
, GFP_KERNEL
, 0);
1506 q
->flags
|= SIGQUEUE_PREALLOC
;
1511 void sigqueue_free(struct sigqueue
*q
)
1513 unsigned long flags
;
1514 spinlock_t
*lock
= ¤t
->sighand
->siglock
;
1516 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1518 * We must hold ->siglock while testing q->list
1519 * to serialize with collect_signal() or with
1520 * __exit_signal()->flush_sigqueue().
1522 spin_lock_irqsave(lock
, flags
);
1523 q
->flags
&= ~SIGQUEUE_PREALLOC
;
1525 * If it is queued it will be freed when dequeued,
1526 * like the "regular" sigqueue.
1528 if (!list_empty(&q
->list
))
1530 spin_unlock_irqrestore(lock
, flags
);
1536 int send_sigqueue(struct sigqueue
*q
, struct task_struct
*t
, int group
)
1538 int sig
= q
->info
.si_signo
;
1539 struct sigpending
*pending
;
1540 unsigned long flags
;
1543 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1546 if (!likely(lock_task_sighand(t
, &flags
)))
1549 ret
= 1; /* the signal is ignored */
1550 if (!prepare_signal(sig
, t
, 0))
1554 if (unlikely(!list_empty(&q
->list
))) {
1556 * If an SI_TIMER entry is already queue just increment
1557 * the overrun count.
1559 BUG_ON(q
->info
.si_code
!= SI_TIMER
);
1560 q
->info
.si_overrun
++;
1563 q
->info
.si_overrun
= 0;
1565 signalfd_notify(t
, sig
);
1566 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
1567 list_add_tail(&q
->list
, &pending
->list
);
1568 sigaddset(&pending
->signal
, sig
);
1569 complete_signal(sig
, t
, group
);
1571 unlock_task_sighand(t
, &flags
);
1577 * Let a parent know about the death of a child.
1578 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1580 * Returns -1 if our parent ignored us and so we've switched to
1581 * self-reaping, or else @sig.
1583 int do_notify_parent(struct task_struct
*tsk
, int sig
)
1585 struct siginfo info
;
1586 unsigned long flags
;
1587 struct sighand_struct
*psig
;
1592 /* do_notify_parent_cldstop should have been called instead. */
1593 BUG_ON(task_is_stopped_or_traced(tsk
));
1595 BUG_ON(!tsk
->ptrace
&&
1596 (tsk
->group_leader
!= tsk
|| !thread_group_empty(tsk
)));
1598 info
.si_signo
= sig
;
1601 * we are under tasklist_lock here so our parent is tied to
1602 * us and cannot exit and release its namespace.
1604 * the only it can is to switch its nsproxy with sys_unshare,
1605 * bu uncharing pid namespaces is not allowed, so we'll always
1606 * see relevant namespace
1608 * write_lock() currently calls preempt_disable() which is the
1609 * same as rcu_read_lock(), but according to Oleg, this is not
1610 * correct to rely on this
1613 info
.si_pid
= task_pid_nr_ns(tsk
, tsk
->parent
->nsproxy
->pid_ns
);
1614 info
.si_uid
= __task_cred(tsk
)->uid
;
1617 info
.si_utime
= cputime_to_clock_t(cputime_add(tsk
->utime
,
1618 tsk
->signal
->utime
));
1619 info
.si_stime
= cputime_to_clock_t(cputime_add(tsk
->stime
,
1620 tsk
->signal
->stime
));
1622 info
.si_status
= tsk
->exit_code
& 0x7f;
1623 if (tsk
->exit_code
& 0x80)
1624 info
.si_code
= CLD_DUMPED
;
1625 else if (tsk
->exit_code
& 0x7f)
1626 info
.si_code
= CLD_KILLED
;
1628 info
.si_code
= CLD_EXITED
;
1629 info
.si_status
= tsk
->exit_code
>> 8;
1632 psig
= tsk
->parent
->sighand
;
1633 spin_lock_irqsave(&psig
->siglock
, flags
);
1634 if (!tsk
->ptrace
&& sig
== SIGCHLD
&&
1635 (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
||
1636 (psig
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDWAIT
))) {
1638 * We are exiting and our parent doesn't care. POSIX.1
1639 * defines special semantics for setting SIGCHLD to SIG_IGN
1640 * or setting the SA_NOCLDWAIT flag: we should be reaped
1641 * automatically and not left for our parent's wait4 call.
1642 * Rather than having the parent do it as a magic kind of
1643 * signal handler, we just set this to tell do_exit that we
1644 * can be cleaned up without becoming a zombie. Note that
1645 * we still call __wake_up_parent in this case, because a
1646 * blocked sys_wait4 might now return -ECHILD.
1648 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1649 * is implementation-defined: we do (if you don't want
1650 * it, just use SIG_IGN instead).
1652 ret
= tsk
->exit_signal
= -1;
1653 if (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
)
1656 if (valid_signal(sig
) && sig
> 0)
1657 __group_send_sig_info(sig
, &info
, tsk
->parent
);
1658 __wake_up_parent(tsk
, tsk
->parent
);
1659 spin_unlock_irqrestore(&psig
->siglock
, flags
);
1665 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1666 * @tsk: task reporting the state change
1667 * @for_ptracer: the notification is for ptracer
1668 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1670 * Notify @tsk's parent that the stopped/continued state has changed. If
1671 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1672 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1675 * Must be called with tasklist_lock at least read locked.
1677 static void do_notify_parent_cldstop(struct task_struct
*tsk
,
1678 bool for_ptracer
, int why
)
1680 struct siginfo info
;
1681 unsigned long flags
;
1682 struct task_struct
*parent
;
1683 struct sighand_struct
*sighand
;
1686 parent
= tsk
->parent
;
1688 tsk
= tsk
->group_leader
;
1689 parent
= tsk
->real_parent
;
1692 info
.si_signo
= SIGCHLD
;
1695 * see comment in do_notify_parent() about the following 4 lines
1698 info
.si_pid
= task_pid_nr_ns(tsk
, parent
->nsproxy
->pid_ns
);
1699 info
.si_uid
= __task_cred(tsk
)->uid
;
1702 info
.si_utime
= cputime_to_clock_t(tsk
->utime
);
1703 info
.si_stime
= cputime_to_clock_t(tsk
->stime
);
1708 info
.si_status
= SIGCONT
;
1711 info
.si_status
= tsk
->signal
->group_exit_code
& 0x7f;
1714 info
.si_status
= tsk
->exit_code
& 0x7f;
1720 sighand
= parent
->sighand
;
1721 spin_lock_irqsave(&sighand
->siglock
, flags
);
1722 if (sighand
->action
[SIGCHLD
-1].sa
.sa_handler
!= SIG_IGN
&&
1723 !(sighand
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDSTOP
))
1724 __group_send_sig_info(SIGCHLD
, &info
, parent
);
1726 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1728 __wake_up_parent(tsk
, parent
);
1729 spin_unlock_irqrestore(&sighand
->siglock
, flags
);
1732 static inline int may_ptrace_stop(void)
1734 if (!likely(current
->ptrace
))
1737 * Are we in the middle of do_coredump?
1738 * If so and our tracer is also part of the coredump stopping
1739 * is a deadlock situation, and pointless because our tracer
1740 * is dead so don't allow us to stop.
1741 * If SIGKILL was already sent before the caller unlocked
1742 * ->siglock we must see ->core_state != NULL. Otherwise it
1743 * is safe to enter schedule().
1745 if (unlikely(current
->mm
->core_state
) &&
1746 unlikely(current
->mm
== current
->parent
->mm
))
1753 * Return non-zero if there is a SIGKILL that should be waking us up.
1754 * Called with the siglock held.
1756 static int sigkill_pending(struct task_struct
*tsk
)
1758 return sigismember(&tsk
->pending
.signal
, SIGKILL
) ||
1759 sigismember(&tsk
->signal
->shared_pending
.signal
, SIGKILL
);
1763 * Test whether the target task of the usual cldstop notification - the
1764 * real_parent of @child - is in the same group as the ptracer.
1766 static bool real_parent_is_ptracer(struct task_struct
*child
)
1768 return same_thread_group(child
->parent
, child
->real_parent
);
1772 * This must be called with current->sighand->siglock held.
1774 * This should be the path for all ptrace stops.
1775 * We always set current->last_siginfo while stopped here.
1776 * That makes it a way to test a stopped process for
1777 * being ptrace-stopped vs being job-control-stopped.
1779 * If we actually decide not to stop at all because the tracer
1780 * is gone, we keep current->exit_code unless clear_code.
1782 static void ptrace_stop(int exit_code
, int why
, int clear_code
, siginfo_t
*info
)
1783 __releases(¤t
->sighand
->siglock
)
1784 __acquires(¤t
->sighand
->siglock
)
1786 bool gstop_done
= false;
1788 if (arch_ptrace_stop_needed(exit_code
, info
)) {
1790 * The arch code has something special to do before a
1791 * ptrace stop. This is allowed to block, e.g. for faults
1792 * on user stack pages. We can't keep the siglock while
1793 * calling arch_ptrace_stop, so we must release it now.
1794 * To preserve proper semantics, we must do this before
1795 * any signal bookkeeping like checking group_stop_count.
1796 * Meanwhile, a SIGKILL could come in before we retake the
1797 * siglock. That must prevent us from sleeping in TASK_TRACED.
1798 * So after regaining the lock, we must check for SIGKILL.
1800 spin_unlock_irq(¤t
->sighand
->siglock
);
1801 arch_ptrace_stop(exit_code
, info
);
1802 spin_lock_irq(¤t
->sighand
->siglock
);
1803 if (sigkill_pending(current
))
1808 * We're committing to trapping. TRACED should be visible before
1809 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1810 * Also, transition to TRACED and updates to ->jobctl should be
1811 * atomic with respect to siglock and should be done after the arch
1812 * hook as siglock is released and regrabbed across it.
1814 set_current_state(TASK_TRACED
);
1816 current
->last_siginfo
= info
;
1817 current
->exit_code
= exit_code
;
1820 * If @why is CLD_STOPPED, we're trapping to participate in a group
1821 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1822 * across siglock relocks since INTERRUPT was scheduled, PENDING
1823 * could be clear now. We act as if SIGCONT is received after
1824 * TASK_TRACED is entered - ignore it.
1826 if (why
== CLD_STOPPED
&& (current
->jobctl
& JOBCTL_STOP_PENDING
))
1827 gstop_done
= task_participate_group_stop(current
);
1829 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1830 task_clear_jobctl_pending(current
, JOBCTL_TRAP_STOP
);
1831 if (info
&& info
->si_code
>> 8 == PTRACE_EVENT_STOP
)
1832 task_clear_jobctl_pending(current
, JOBCTL_TRAP_NOTIFY
);
1834 /* entering a trap, clear TRAPPING */
1835 task_clear_jobctl_trapping(current
);
1837 spin_unlock_irq(¤t
->sighand
->siglock
);
1838 read_lock(&tasklist_lock
);
1839 if (may_ptrace_stop()) {
1841 * Notify parents of the stop.
1843 * While ptraced, there are two parents - the ptracer and
1844 * the real_parent of the group_leader. The ptracer should
1845 * know about every stop while the real parent is only
1846 * interested in the completion of group stop. The states
1847 * for the two don't interact with each other. Notify
1848 * separately unless they're gonna be duplicates.
1850 do_notify_parent_cldstop(current
, true, why
);
1851 if (gstop_done
&& !real_parent_is_ptracer(current
))
1852 do_notify_parent_cldstop(current
, false, why
);
1855 * Don't want to allow preemption here, because
1856 * sys_ptrace() needs this task to be inactive.
1858 * XXX: implement read_unlock_no_resched().
1861 read_unlock(&tasklist_lock
);
1862 preempt_enable_no_resched();
1866 * By the time we got the lock, our tracer went away.
1867 * Don't drop the lock yet, another tracer may come.
1869 * If @gstop_done, the ptracer went away between group stop
1870 * completion and here. During detach, it would have set
1871 * JOBCTL_STOP_PENDING on us and we'll re-enter
1872 * TASK_STOPPED in do_signal_stop() on return, so notifying
1873 * the real parent of the group stop completion is enough.
1876 do_notify_parent_cldstop(current
, false, why
);
1878 __set_current_state(TASK_RUNNING
);
1880 current
->exit_code
= 0;
1881 read_unlock(&tasklist_lock
);
1885 * While in TASK_TRACED, we were considered "frozen enough".
1886 * Now that we woke up, it's crucial if we're supposed to be
1887 * frozen that we freeze now before running anything substantial.
1892 * We are back. Now reacquire the siglock before touching
1893 * last_siginfo, so that we are sure to have synchronized with
1894 * any signal-sending on another CPU that wants to examine it.
1896 spin_lock_irq(¤t
->sighand
->siglock
);
1897 current
->last_siginfo
= NULL
;
1899 /* LISTENING can be set only during STOP traps, clear it */
1900 current
->jobctl
&= ~JOBCTL_LISTENING
;
1903 * Queued signals ignored us while we were stopped for tracing.
1904 * So check for any that we should take before resuming user mode.
1905 * This sets TIF_SIGPENDING, but never clears it.
1907 recalc_sigpending_tsk(current
);
1910 static void ptrace_do_notify(int signr
, int exit_code
, int why
)
1914 memset(&info
, 0, sizeof info
);
1915 info
.si_signo
= signr
;
1916 info
.si_code
= exit_code
;
1917 info
.si_pid
= task_pid_vnr(current
);
1918 info
.si_uid
= current_uid();
1920 /* Let the debugger run. */
1921 ptrace_stop(exit_code
, why
, 1, &info
);
1924 void ptrace_notify(int exit_code
)
1926 BUG_ON((exit_code
& (0x7f | ~0xffff)) != SIGTRAP
);
1928 spin_lock_irq(¤t
->sighand
->siglock
);
1929 ptrace_do_notify(SIGTRAP
, exit_code
, CLD_TRAPPED
);
1930 spin_unlock_irq(¤t
->sighand
->siglock
);
1934 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1935 * @signr: signr causing group stop if initiating
1937 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1938 * and participate in it. If already set, participate in the existing
1939 * group stop. If participated in a group stop (and thus slept), %true is
1940 * returned with siglock released.
1942 * If ptraced, this function doesn't handle stop itself. Instead,
1943 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1944 * untouched. The caller must ensure that INTERRUPT trap handling takes
1945 * places afterwards.
1948 * Must be called with @current->sighand->siglock held, which is released
1952 * %false if group stop is already cancelled or ptrace trap is scheduled.
1953 * %true if participated in group stop.
1955 static bool do_signal_stop(int signr
)
1956 __releases(¤t
->sighand
->siglock
)
1958 struct signal_struct
*sig
= current
->signal
;
1960 if (!(current
->jobctl
& JOBCTL_STOP_PENDING
)) {
1961 unsigned int gstop
= JOBCTL_STOP_PENDING
| JOBCTL_STOP_CONSUME
;
1962 struct task_struct
*t
;
1964 /* signr will be recorded in task->jobctl for retries */
1965 WARN_ON_ONCE(signr
& ~JOBCTL_STOP_SIGMASK
);
1967 if (!likely(current
->jobctl
& JOBCTL_STOP_DEQUEUED
) ||
1968 unlikely(signal_group_exit(sig
)))
1971 * There is no group stop already in progress. We must
1974 * While ptraced, a task may be resumed while group stop is
1975 * still in effect and then receive a stop signal and
1976 * initiate another group stop. This deviates from the
1977 * usual behavior as two consecutive stop signals can't
1978 * cause two group stops when !ptraced. That is why we
1979 * also check !task_is_stopped(t) below.
1981 * The condition can be distinguished by testing whether
1982 * SIGNAL_STOP_STOPPED is already set. Don't generate
1983 * group_exit_code in such case.
1985 * This is not necessary for SIGNAL_STOP_CONTINUED because
1986 * an intervening stop signal is required to cause two
1987 * continued events regardless of ptrace.
1989 if (!(sig
->flags
& SIGNAL_STOP_STOPPED
))
1990 sig
->group_exit_code
= signr
;
1992 WARN_ON_ONCE(!current
->ptrace
);
1994 sig
->group_stop_count
= 0;
1996 if (task_set_jobctl_pending(current
, signr
| gstop
))
1997 sig
->group_stop_count
++;
1999 for (t
= next_thread(current
); t
!= current
;
2000 t
= next_thread(t
)) {
2002 * Setting state to TASK_STOPPED for a group
2003 * stop is always done with the siglock held,
2004 * so this check has no races.
2006 if (!task_is_stopped(t
) &&
2007 task_set_jobctl_pending(t
, signr
| gstop
)) {
2008 sig
->group_stop_count
++;
2009 if (likely(!(t
->ptrace
& PT_SEIZED
)))
2010 signal_wake_up(t
, 0);
2012 ptrace_trap_notify(t
);
2017 if (likely(!current
->ptrace
)) {
2021 * If there are no other threads in the group, or if there
2022 * is a group stop in progress and we are the last to stop,
2023 * report to the parent.
2025 if (task_participate_group_stop(current
))
2026 notify
= CLD_STOPPED
;
2028 __set_current_state(TASK_STOPPED
);
2029 spin_unlock_irq(¤t
->sighand
->siglock
);
2032 * Notify the parent of the group stop completion. Because
2033 * we're not holding either the siglock or tasklist_lock
2034 * here, ptracer may attach inbetween; however, this is for
2035 * group stop and should always be delivered to the real
2036 * parent of the group leader. The new ptracer will get
2037 * its notification when this task transitions into
2041 read_lock(&tasklist_lock
);
2042 do_notify_parent_cldstop(current
, false, notify
);
2043 read_unlock(&tasklist_lock
);
2046 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2051 * While ptraced, group stop is handled by STOP trap.
2052 * Schedule it and let the caller deal with it.
2054 task_set_jobctl_pending(current
, JOBCTL_TRAP_STOP
);
2060 * do_jobctl_trap - take care of ptrace jobctl traps
2062 * When PT_SEIZED, it's used for both group stop and explicit
2063 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2064 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2065 * the stop signal; otherwise, %SIGTRAP.
2067 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2068 * number as exit_code and no siginfo.
2071 * Must be called with @current->sighand->siglock held, which may be
2072 * released and re-acquired before returning with intervening sleep.
2074 static void do_jobctl_trap(void)
2076 struct signal_struct
*signal
= current
->signal
;
2077 int signr
= current
->jobctl
& JOBCTL_STOP_SIGMASK
;
2079 if (current
->ptrace
& PT_SEIZED
) {
2080 if (!signal
->group_stop_count
&&
2081 !(signal
->flags
& SIGNAL_STOP_STOPPED
))
2083 WARN_ON_ONCE(!signr
);
2084 ptrace_do_notify(signr
, signr
| (PTRACE_EVENT_STOP
<< 8),
2087 WARN_ON_ONCE(!signr
);
2088 ptrace_stop(signr
, CLD_STOPPED
, 0, NULL
);
2089 current
->exit_code
= 0;
2093 static int ptrace_signal(int signr
, siginfo_t
*info
,
2094 struct pt_regs
*regs
, void *cookie
)
2096 if (!current
->ptrace
)
2099 ptrace_signal_deliver(regs
, cookie
);
2101 /* Let the debugger run. */
2102 ptrace_stop(signr
, CLD_TRAPPED
, 0, info
);
2104 /* We're back. Did the debugger cancel the sig? */
2105 signr
= current
->exit_code
;
2109 current
->exit_code
= 0;
2112 * Update the siginfo structure if the signal has
2113 * changed. If the debugger wanted something
2114 * specific in the siginfo structure then it should
2115 * have updated *info via PTRACE_SETSIGINFO.
2117 if (signr
!= info
->si_signo
) {
2118 info
->si_signo
= signr
;
2120 info
->si_code
= SI_USER
;
2121 info
->si_pid
= task_pid_vnr(current
->parent
);
2122 info
->si_uid
= task_uid(current
->parent
);
2125 /* If the (new) signal is now blocked, requeue it. */
2126 if (sigismember(¤t
->blocked
, signr
)) {
2127 specific_send_sig_info(signr
, info
, current
);
2134 int get_signal_to_deliver(siginfo_t
*info
, struct k_sigaction
*return_ka
,
2135 struct pt_regs
*regs
, void *cookie
)
2137 struct sighand_struct
*sighand
= current
->sighand
;
2138 struct signal_struct
*signal
= current
->signal
;
2143 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2144 * While in TASK_STOPPED, we were considered "frozen enough".
2145 * Now that we woke up, it's crucial if we're supposed to be
2146 * frozen that we freeze now before running anything substantial.
2150 spin_lock_irq(&sighand
->siglock
);
2152 * Every stopped thread goes here after wakeup. Check to see if
2153 * we should notify the parent, prepare_signal(SIGCONT) encodes
2154 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2156 if (unlikely(signal
->flags
& SIGNAL_CLD_MASK
)) {
2157 struct task_struct
*leader
;
2160 if (signal
->flags
& SIGNAL_CLD_CONTINUED
)
2161 why
= CLD_CONTINUED
;
2165 signal
->flags
&= ~SIGNAL_CLD_MASK
;
2167 spin_unlock_irq(&sighand
->siglock
);
2170 * Notify the parent that we're continuing. This event is
2171 * always per-process and doesn't make whole lot of sense
2172 * for ptracers, who shouldn't consume the state via
2173 * wait(2) either, but, for backward compatibility, notify
2174 * the ptracer of the group leader too unless it's gonna be
2177 read_lock(&tasklist_lock
);
2179 do_notify_parent_cldstop(current
, false, why
);
2181 leader
= current
->group_leader
;
2182 if (leader
->ptrace
&& !real_parent_is_ptracer(leader
))
2183 do_notify_parent_cldstop(leader
, true, why
);
2185 read_unlock(&tasklist_lock
);
2191 struct k_sigaction
*ka
;
2193 if (unlikely(current
->jobctl
& JOBCTL_STOP_PENDING
) &&
2197 if (unlikely(current
->jobctl
& JOBCTL_TRAP_MASK
)) {
2199 spin_unlock_irq(&sighand
->siglock
);
2203 signr
= dequeue_signal(current
, ¤t
->blocked
, info
);
2206 break; /* will return 0 */
2208 if (signr
!= SIGKILL
) {
2209 signr
= ptrace_signal(signr
, info
,
2215 ka
= &sighand
->action
[signr
-1];
2217 /* Trace actually delivered signals. */
2218 trace_signal_deliver(signr
, info
, ka
);
2220 if (ka
->sa
.sa_handler
== SIG_IGN
) /* Do nothing. */
2222 if (ka
->sa
.sa_handler
!= SIG_DFL
) {
2223 /* Run the handler. */
2226 if (ka
->sa
.sa_flags
& SA_ONESHOT
)
2227 ka
->sa
.sa_handler
= SIG_DFL
;
2229 break; /* will return non-zero "signr" value */
2233 * Now we are doing the default action for this signal.
2235 if (sig_kernel_ignore(signr
)) /* Default is nothing. */
2239 * Global init gets no signals it doesn't want.
2240 * Container-init gets no signals it doesn't want from same
2243 * Note that if global/container-init sees a sig_kernel_only()
2244 * signal here, the signal must have been generated internally
2245 * or must have come from an ancestor namespace. In either
2246 * case, the signal cannot be dropped.
2248 if (unlikely(signal
->flags
& SIGNAL_UNKILLABLE
) &&
2249 !sig_kernel_only(signr
))
2252 if (sig_kernel_stop(signr
)) {
2254 * The default action is to stop all threads in
2255 * the thread group. The job control signals
2256 * do nothing in an orphaned pgrp, but SIGSTOP
2257 * always works. Note that siglock needs to be
2258 * dropped during the call to is_orphaned_pgrp()
2259 * because of lock ordering with tasklist_lock.
2260 * This allows an intervening SIGCONT to be posted.
2261 * We need to check for that and bail out if necessary.
2263 if (signr
!= SIGSTOP
) {
2264 spin_unlock_irq(&sighand
->siglock
);
2266 /* signals can be posted during this window */
2268 if (is_current_pgrp_orphaned())
2271 spin_lock_irq(&sighand
->siglock
);
2274 if (likely(do_signal_stop(info
->si_signo
))) {
2275 /* It released the siglock. */
2280 * We didn't actually stop, due to a race
2281 * with SIGCONT or something like that.
2286 spin_unlock_irq(&sighand
->siglock
);
2289 * Anything else is fatal, maybe with a core dump.
2291 current
->flags
|= PF_SIGNALED
;
2293 if (sig_kernel_coredump(signr
)) {
2294 if (print_fatal_signals
)
2295 print_fatal_signal(regs
, info
->si_signo
);
2297 * If it was able to dump core, this kills all
2298 * other threads in the group and synchronizes with
2299 * their demise. If we lost the race with another
2300 * thread getting here, it set group_exit_code
2301 * first and our do_group_exit call below will use
2302 * that value and ignore the one we pass it.
2304 do_coredump(info
->si_signo
, info
->si_signo
, regs
);
2308 * Death signals, no core dump.
2310 do_group_exit(info
->si_signo
);
2313 spin_unlock_irq(&sighand
->siglock
);
2318 * It could be that complete_signal() picked us to notify about the
2319 * group-wide signal. Other threads should be notified now to take
2320 * the shared signals in @which since we will not.
2322 static void retarget_shared_pending(struct task_struct
*tsk
, sigset_t
*which
)
2325 struct task_struct
*t
;
2327 sigandsets(&retarget
, &tsk
->signal
->shared_pending
.signal
, which
);
2328 if (sigisemptyset(&retarget
))
2332 while_each_thread(tsk
, t
) {
2333 if (t
->flags
& PF_EXITING
)
2336 if (!has_pending_signals(&retarget
, &t
->blocked
))
2338 /* Remove the signals this thread can handle. */
2339 sigandsets(&retarget
, &retarget
, &t
->blocked
);
2341 if (!signal_pending(t
))
2342 signal_wake_up(t
, 0);
2344 if (sigisemptyset(&retarget
))
2349 void exit_signals(struct task_struct
*tsk
)
2354 if (thread_group_empty(tsk
) || signal_group_exit(tsk
->signal
)) {
2355 tsk
->flags
|= PF_EXITING
;
2359 spin_lock_irq(&tsk
->sighand
->siglock
);
2361 * From now this task is not visible for group-wide signals,
2362 * see wants_signal(), do_signal_stop().
2364 tsk
->flags
|= PF_EXITING
;
2365 if (!signal_pending(tsk
))
2368 unblocked
= tsk
->blocked
;
2369 signotset(&unblocked
);
2370 retarget_shared_pending(tsk
, &unblocked
);
2372 if (unlikely(tsk
->jobctl
& JOBCTL_STOP_PENDING
) &&
2373 task_participate_group_stop(tsk
))
2374 group_stop
= CLD_STOPPED
;
2376 spin_unlock_irq(&tsk
->sighand
->siglock
);
2379 * If group stop has completed, deliver the notification. This
2380 * should always go to the real parent of the group leader.
2382 if (unlikely(group_stop
)) {
2383 read_lock(&tasklist_lock
);
2384 do_notify_parent_cldstop(tsk
, false, group_stop
);
2385 read_unlock(&tasklist_lock
);
2389 EXPORT_SYMBOL(recalc_sigpending
);
2390 EXPORT_SYMBOL_GPL(dequeue_signal
);
2391 EXPORT_SYMBOL(flush_signals
);
2392 EXPORT_SYMBOL(force_sig
);
2393 EXPORT_SYMBOL(send_sig
);
2394 EXPORT_SYMBOL(send_sig_info
);
2395 EXPORT_SYMBOL(sigprocmask
);
2396 EXPORT_SYMBOL(block_all_signals
);
2397 EXPORT_SYMBOL(unblock_all_signals
);
2401 * System call entry points.
2405 * sys_restart_syscall - restart a system call
2407 SYSCALL_DEFINE0(restart_syscall
)
2409 struct restart_block
*restart
= ¤t_thread_info()->restart_block
;
2410 return restart
->fn(restart
);
2413 long do_no_restart_syscall(struct restart_block
*param
)
2418 static void __set_task_blocked(struct task_struct
*tsk
, const sigset_t
*newset
)
2420 if (signal_pending(tsk
) && !thread_group_empty(tsk
)) {
2421 sigset_t newblocked
;
2422 /* A set of now blocked but previously unblocked signals. */
2423 sigandnsets(&newblocked
, newset
, ¤t
->blocked
);
2424 retarget_shared_pending(tsk
, &newblocked
);
2426 tsk
->blocked
= *newset
;
2427 recalc_sigpending();
2431 * set_current_blocked - change current->blocked mask
2434 * It is wrong to change ->blocked directly, this helper should be used
2435 * to ensure the process can't miss a shared signal we are going to block.
2437 void set_current_blocked(const sigset_t
*newset
)
2439 struct task_struct
*tsk
= current
;
2441 spin_lock_irq(&tsk
->sighand
->siglock
);
2442 __set_task_blocked(tsk
, newset
);
2443 spin_unlock_irq(&tsk
->sighand
->siglock
);
2447 * This is also useful for kernel threads that want to temporarily
2448 * (or permanently) block certain signals.
2450 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2451 * interface happily blocks "unblockable" signals like SIGKILL
2454 int sigprocmask(int how
, sigset_t
*set
, sigset_t
*oldset
)
2456 struct task_struct
*tsk
= current
;
2459 /* Lockless, only current can change ->blocked, never from irq */
2461 *oldset
= tsk
->blocked
;
2465 sigorsets(&newset
, &tsk
->blocked
, set
);
2468 sigandnsets(&newset
, &tsk
->blocked
, set
);
2477 set_current_blocked(&newset
);
2482 * sys_rt_sigprocmask - change the list of currently blocked signals
2483 * @how: whether to add, remove, or set signals
2484 * @set: stores pending signals
2485 * @oset: previous value of signal mask if non-null
2486 * @sigsetsize: size of sigset_t type
2488 SYSCALL_DEFINE4(rt_sigprocmask
, int, how
, sigset_t __user
*, nset
,
2489 sigset_t __user
*, oset
, size_t, sigsetsize
)
2491 sigset_t old_set
, new_set
;
2494 /* XXX: Don't preclude handling different sized sigset_t's. */
2495 if (sigsetsize
!= sizeof(sigset_t
))
2498 old_set
= current
->blocked
;
2501 if (copy_from_user(&new_set
, nset
, sizeof(sigset_t
)))
2503 sigdelsetmask(&new_set
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2505 error
= sigprocmask(how
, &new_set
, NULL
);
2511 if (copy_to_user(oset
, &old_set
, sizeof(sigset_t
)))
2518 long do_sigpending(void __user
*set
, unsigned long sigsetsize
)
2520 long error
= -EINVAL
;
2523 if (sigsetsize
> sizeof(sigset_t
))
2526 spin_lock_irq(¤t
->sighand
->siglock
);
2527 sigorsets(&pending
, ¤t
->pending
.signal
,
2528 ¤t
->signal
->shared_pending
.signal
);
2529 spin_unlock_irq(¤t
->sighand
->siglock
);
2531 /* Outside the lock because only this thread touches it. */
2532 sigandsets(&pending
, ¤t
->blocked
, &pending
);
2535 if (!copy_to_user(set
, &pending
, sigsetsize
))
2543 * sys_rt_sigpending - examine a pending signal that has been raised
2545 * @set: stores pending signals
2546 * @sigsetsize: size of sigset_t type or larger
2548 SYSCALL_DEFINE2(rt_sigpending
, sigset_t __user
*, set
, size_t, sigsetsize
)
2550 return do_sigpending(set
, sigsetsize
);
2553 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2555 int copy_siginfo_to_user(siginfo_t __user
*to
, siginfo_t
*from
)
2559 if (!access_ok (VERIFY_WRITE
, to
, sizeof(siginfo_t
)))
2561 if (from
->si_code
< 0)
2562 return __copy_to_user(to
, from
, sizeof(siginfo_t
))
2565 * If you change siginfo_t structure, please be sure
2566 * this code is fixed accordingly.
2567 * Please remember to update the signalfd_copyinfo() function
2568 * inside fs/signalfd.c too, in case siginfo_t changes.
2569 * It should never copy any pad contained in the structure
2570 * to avoid security leaks, but must copy the generic
2571 * 3 ints plus the relevant union member.
2573 err
= __put_user(from
->si_signo
, &to
->si_signo
);
2574 err
|= __put_user(from
->si_errno
, &to
->si_errno
);
2575 err
|= __put_user((short)from
->si_code
, &to
->si_code
);
2576 switch (from
->si_code
& __SI_MASK
) {
2578 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2579 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2582 err
|= __put_user(from
->si_tid
, &to
->si_tid
);
2583 err
|= __put_user(from
->si_overrun
, &to
->si_overrun
);
2584 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2587 err
|= __put_user(from
->si_band
, &to
->si_band
);
2588 err
|= __put_user(from
->si_fd
, &to
->si_fd
);
2591 err
|= __put_user(from
->si_addr
, &to
->si_addr
);
2592 #ifdef __ARCH_SI_TRAPNO
2593 err
|= __put_user(from
->si_trapno
, &to
->si_trapno
);
2595 #ifdef BUS_MCEERR_AO
2597 * Other callers might not initialize the si_lsb field,
2598 * so check explicitly for the right codes here.
2600 if (from
->si_code
== BUS_MCEERR_AR
|| from
->si_code
== BUS_MCEERR_AO
)
2601 err
|= __put_user(from
->si_addr_lsb
, &to
->si_addr_lsb
);
2605 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2606 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2607 err
|= __put_user(from
->si_status
, &to
->si_status
);
2608 err
|= __put_user(from
->si_utime
, &to
->si_utime
);
2609 err
|= __put_user(from
->si_stime
, &to
->si_stime
);
2611 case __SI_RT
: /* This is not generated by the kernel as of now. */
2612 case __SI_MESGQ
: /* But this is */
2613 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2614 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2615 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2617 default: /* this is just in case for now ... */
2618 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2619 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2628 * do_sigtimedwait - wait for queued signals specified in @which
2629 * @which: queued signals to wait for
2630 * @info: if non-null, the signal's siginfo is returned here
2631 * @ts: upper bound on process time suspension
2633 int do_sigtimedwait(const sigset_t
*which
, siginfo_t
*info
,
2634 const struct timespec
*ts
)
2636 struct task_struct
*tsk
= current
;
2637 long timeout
= MAX_SCHEDULE_TIMEOUT
;
2638 sigset_t mask
= *which
;
2642 if (!timespec_valid(ts
))
2644 timeout
= timespec_to_jiffies(ts
);
2646 * We can be close to the next tick, add another one
2647 * to ensure we will wait at least the time asked for.
2649 if (ts
->tv_sec
|| ts
->tv_nsec
)
2654 * Invert the set of allowed signals to get those we want to block.
2656 sigdelsetmask(&mask
, sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2659 spin_lock_irq(&tsk
->sighand
->siglock
);
2660 sig
= dequeue_signal(tsk
, &mask
, info
);
2661 if (!sig
&& timeout
) {
2663 * None ready, temporarily unblock those we're interested
2664 * while we are sleeping in so that we'll be awakened when
2665 * they arrive. Unblocking is always fine, we can avoid
2666 * set_current_blocked().
2668 tsk
->real_blocked
= tsk
->blocked
;
2669 sigandsets(&tsk
->blocked
, &tsk
->blocked
, &mask
);
2670 recalc_sigpending();
2671 spin_unlock_irq(&tsk
->sighand
->siglock
);
2673 timeout
= schedule_timeout_interruptible(timeout
);
2675 spin_lock_irq(&tsk
->sighand
->siglock
);
2676 __set_task_blocked(tsk
, &tsk
->real_blocked
);
2677 siginitset(&tsk
->real_blocked
, 0);
2678 sig
= dequeue_signal(tsk
, &mask
, info
);
2680 spin_unlock_irq(&tsk
->sighand
->siglock
);
2684 return timeout
? -EINTR
: -EAGAIN
;
2688 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2690 * @uthese: queued signals to wait for
2691 * @uinfo: if non-null, the signal's siginfo is returned here
2692 * @uts: upper bound on process time suspension
2693 * @sigsetsize: size of sigset_t type
2695 SYSCALL_DEFINE4(rt_sigtimedwait
, const sigset_t __user
*, uthese
,
2696 siginfo_t __user
*, uinfo
, const struct timespec __user
*, uts
,
2704 /* XXX: Don't preclude handling different sized sigset_t's. */
2705 if (sigsetsize
!= sizeof(sigset_t
))
2708 if (copy_from_user(&these
, uthese
, sizeof(these
)))
2712 if (copy_from_user(&ts
, uts
, sizeof(ts
)))
2716 ret
= do_sigtimedwait(&these
, &info
, uts
? &ts
: NULL
);
2718 if (ret
> 0 && uinfo
) {
2719 if (copy_siginfo_to_user(uinfo
, &info
))
2727 * sys_kill - send a signal to a process
2728 * @pid: the PID of the process
2729 * @sig: signal to be sent
2731 SYSCALL_DEFINE2(kill
, pid_t
, pid
, int, sig
)
2733 struct siginfo info
;
2735 info
.si_signo
= sig
;
2737 info
.si_code
= SI_USER
;
2738 info
.si_pid
= task_tgid_vnr(current
);
2739 info
.si_uid
= current_uid();
2741 return kill_something_info(sig
, &info
, pid
);
2745 do_send_specific(pid_t tgid
, pid_t pid
, int sig
, struct siginfo
*info
)
2747 struct task_struct
*p
;
2751 p
= find_task_by_vpid(pid
);
2752 if (p
&& (tgid
<= 0 || task_tgid_vnr(p
) == tgid
)) {
2753 error
= check_kill_permission(sig
, info
, p
);
2755 * The null signal is a permissions and process existence
2756 * probe. No signal is actually delivered.
2758 if (!error
&& sig
) {
2759 error
= do_send_sig_info(sig
, info
, p
, false);
2761 * If lock_task_sighand() failed we pretend the task
2762 * dies after receiving the signal. The window is tiny,
2763 * and the signal is private anyway.
2765 if (unlikely(error
== -ESRCH
))
2774 static int do_tkill(pid_t tgid
, pid_t pid
, int sig
)
2776 struct siginfo info
;
2778 info
.si_signo
= sig
;
2780 info
.si_code
= SI_TKILL
;
2781 info
.si_pid
= task_tgid_vnr(current
);
2782 info
.si_uid
= current_uid();
2784 return do_send_specific(tgid
, pid
, sig
, &info
);
2788 * sys_tgkill - send signal to one specific thread
2789 * @tgid: the thread group ID of the thread
2790 * @pid: the PID of the thread
2791 * @sig: signal to be sent
2793 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2794 * exists but it's not belonging to the target process anymore. This
2795 * method solves the problem of threads exiting and PIDs getting reused.
2797 SYSCALL_DEFINE3(tgkill
, pid_t
, tgid
, pid_t
, pid
, int, sig
)
2799 /* This is only valid for single tasks */
2800 if (pid
<= 0 || tgid
<= 0)
2803 return do_tkill(tgid
, pid
, sig
);
2807 * sys_tkill - send signal to one specific task
2808 * @pid: the PID of the task
2809 * @sig: signal to be sent
2811 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2813 SYSCALL_DEFINE2(tkill
, pid_t
, pid
, int, sig
)
2815 /* This is only valid for single tasks */
2819 return do_tkill(0, pid
, sig
);
2823 * sys_rt_sigqueueinfo - send signal information to a signal
2824 * @pid: the PID of the thread
2825 * @sig: signal to be sent
2826 * @uinfo: signal info to be sent
2828 SYSCALL_DEFINE3(rt_sigqueueinfo
, pid_t
, pid
, int, sig
,
2829 siginfo_t __user
*, uinfo
)
2833 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
2836 /* Not even root can pretend to send signals from the kernel.
2837 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2839 if (info
.si_code
>= 0 || info
.si_code
== SI_TKILL
) {
2840 /* We used to allow any < 0 si_code */
2841 WARN_ON_ONCE(info
.si_code
< 0);
2844 info
.si_signo
= sig
;
2846 /* POSIX.1b doesn't mention process groups. */
2847 return kill_proc_info(sig
, &info
, pid
);
2850 long do_rt_tgsigqueueinfo(pid_t tgid
, pid_t pid
, int sig
, siginfo_t
*info
)
2852 /* This is only valid for single tasks */
2853 if (pid
<= 0 || tgid
<= 0)
2856 /* Not even root can pretend to send signals from the kernel.
2857 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2859 if (info
->si_code
>= 0 || info
->si_code
== SI_TKILL
) {
2860 /* We used to allow any < 0 si_code */
2861 WARN_ON_ONCE(info
->si_code
< 0);
2864 info
->si_signo
= sig
;
2866 return do_send_specific(tgid
, pid
, sig
, info
);
2869 SYSCALL_DEFINE4(rt_tgsigqueueinfo
, pid_t
, tgid
, pid_t
, pid
, int, sig
,
2870 siginfo_t __user
*, uinfo
)
2874 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
2877 return do_rt_tgsigqueueinfo(tgid
, pid
, sig
, &info
);
2880 int do_sigaction(int sig
, struct k_sigaction
*act
, struct k_sigaction
*oact
)
2882 struct task_struct
*t
= current
;
2883 struct k_sigaction
*k
;
2886 if (!valid_signal(sig
) || sig
< 1 || (act
&& sig_kernel_only(sig
)))
2889 k
= &t
->sighand
->action
[sig
-1];
2891 spin_lock_irq(¤t
->sighand
->siglock
);
2896 sigdelsetmask(&act
->sa
.sa_mask
,
2897 sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2901 * "Setting a signal action to SIG_IGN for a signal that is
2902 * pending shall cause the pending signal to be discarded,
2903 * whether or not it is blocked."
2905 * "Setting a signal action to SIG_DFL for a signal that is
2906 * pending and whose default action is to ignore the signal
2907 * (for example, SIGCHLD), shall cause the pending signal to
2908 * be discarded, whether or not it is blocked"
2910 if (sig_handler_ignored(sig_handler(t
, sig
), sig
)) {
2912 sigaddset(&mask
, sig
);
2913 rm_from_queue_full(&mask
, &t
->signal
->shared_pending
);
2915 rm_from_queue_full(&mask
, &t
->pending
);
2917 } while (t
!= current
);
2921 spin_unlock_irq(¤t
->sighand
->siglock
);
2926 do_sigaltstack (const stack_t __user
*uss
, stack_t __user
*uoss
, unsigned long sp
)
2931 oss
.ss_sp
= (void __user
*) current
->sas_ss_sp
;
2932 oss
.ss_size
= current
->sas_ss_size
;
2933 oss
.ss_flags
= sas_ss_flags(sp
);
2941 if (!access_ok(VERIFY_READ
, uss
, sizeof(*uss
)))
2943 error
= __get_user(ss_sp
, &uss
->ss_sp
) |
2944 __get_user(ss_flags
, &uss
->ss_flags
) |
2945 __get_user(ss_size
, &uss
->ss_size
);
2950 if (on_sig_stack(sp
))
2955 * Note - this code used to test ss_flags incorrectly:
2956 * old code may have been written using ss_flags==0
2957 * to mean ss_flags==SS_ONSTACK (as this was the only
2958 * way that worked) - this fix preserves that older
2961 if (ss_flags
!= SS_DISABLE
&& ss_flags
!= SS_ONSTACK
&& ss_flags
!= 0)
2964 if (ss_flags
== SS_DISABLE
) {
2969 if (ss_size
< MINSIGSTKSZ
)
2973 current
->sas_ss_sp
= (unsigned long) ss_sp
;
2974 current
->sas_ss_size
= ss_size
;
2980 if (!access_ok(VERIFY_WRITE
, uoss
, sizeof(*uoss
)))
2982 error
= __put_user(oss
.ss_sp
, &uoss
->ss_sp
) |
2983 __put_user(oss
.ss_size
, &uoss
->ss_size
) |
2984 __put_user(oss
.ss_flags
, &uoss
->ss_flags
);
2991 #ifdef __ARCH_WANT_SYS_SIGPENDING
2994 * sys_sigpending - examine pending signals
2995 * @set: where mask of pending signal is returned
2997 SYSCALL_DEFINE1(sigpending
, old_sigset_t __user
*, set
)
2999 return do_sigpending(set
, sizeof(*set
));
3004 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3006 * sys_sigprocmask - examine and change blocked signals
3007 * @how: whether to add, remove, or set signals
3008 * @nset: signals to add or remove (if non-null)
3009 * @oset: previous value of signal mask if non-null
3011 * Some platforms have their own version with special arguments;
3012 * others support only sys_rt_sigprocmask.
3015 SYSCALL_DEFINE3(sigprocmask
, int, how
, old_sigset_t __user
*, nset
,
3016 old_sigset_t __user
*, oset
)
3018 old_sigset_t old_set
, new_set
;
3019 sigset_t new_blocked
;
3021 old_set
= current
->blocked
.sig
[0];
3024 if (copy_from_user(&new_set
, nset
, sizeof(*nset
)))
3026 new_set
&= ~(sigmask(SIGKILL
) | sigmask(SIGSTOP
));
3028 new_blocked
= current
->blocked
;
3032 sigaddsetmask(&new_blocked
, new_set
);
3035 sigdelsetmask(&new_blocked
, new_set
);
3038 new_blocked
.sig
[0] = new_set
;
3044 set_current_blocked(&new_blocked
);
3048 if (copy_to_user(oset
, &old_set
, sizeof(*oset
)))
3054 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3056 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3058 * sys_rt_sigaction - alter an action taken by a process
3059 * @sig: signal to be sent
3060 * @act: new sigaction
3061 * @oact: used to save the previous sigaction
3062 * @sigsetsize: size of sigset_t type
3064 SYSCALL_DEFINE4(rt_sigaction
, int, sig
,
3065 const struct sigaction __user
*, act
,
3066 struct sigaction __user
*, oact
,
3069 struct k_sigaction new_sa
, old_sa
;
3072 /* XXX: Don't preclude handling different sized sigset_t's. */
3073 if (sigsetsize
!= sizeof(sigset_t
))
3077 if (copy_from_user(&new_sa
.sa
, act
, sizeof(new_sa
.sa
)))
3081 ret
= do_sigaction(sig
, act
? &new_sa
: NULL
, oact
? &old_sa
: NULL
);
3084 if (copy_to_user(oact
, &old_sa
.sa
, sizeof(old_sa
.sa
)))
3090 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3092 #ifdef __ARCH_WANT_SYS_SGETMASK
3095 * For backwards compatibility. Functionality superseded by sigprocmask.
3097 SYSCALL_DEFINE0(sgetmask
)
3100 return current
->blocked
.sig
[0];
3103 SYSCALL_DEFINE1(ssetmask
, int, newmask
)
3107 spin_lock_irq(¤t
->sighand
->siglock
);
3108 old
= current
->blocked
.sig
[0];
3110 siginitset(¤t
->blocked
, newmask
& ~(sigmask(SIGKILL
)|
3112 recalc_sigpending();
3113 spin_unlock_irq(¤t
->sighand
->siglock
);
3117 #endif /* __ARCH_WANT_SGETMASK */
3119 #ifdef __ARCH_WANT_SYS_SIGNAL
3121 * For backwards compatibility. Functionality superseded by sigaction.
3123 SYSCALL_DEFINE2(signal
, int, sig
, __sighandler_t
, handler
)
3125 struct k_sigaction new_sa
, old_sa
;
3128 new_sa
.sa
.sa_handler
= handler
;
3129 new_sa
.sa
.sa_flags
= SA_ONESHOT
| SA_NOMASK
;
3130 sigemptyset(&new_sa
.sa
.sa_mask
);
3132 ret
= do_sigaction(sig
, &new_sa
, &old_sa
);
3134 return ret
? ret
: (unsigned long)old_sa
.sa
.sa_handler
;
3136 #endif /* __ARCH_WANT_SYS_SIGNAL */
3138 #ifdef __ARCH_WANT_SYS_PAUSE
3140 SYSCALL_DEFINE0(pause
)
3142 while (!signal_pending(current
)) {
3143 current
->state
= TASK_INTERRUPTIBLE
;
3146 return -ERESTARTNOHAND
;
3151 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3153 * sys_rt_sigsuspend - replace the signal mask for a value with the
3154 * @unewset value until a signal is received
3155 * @unewset: new signal mask value
3156 * @sigsetsize: size of sigset_t type
3158 SYSCALL_DEFINE2(rt_sigsuspend
, sigset_t __user
*, unewset
, size_t, sigsetsize
)
3162 /* XXX: Don't preclude handling different sized sigset_t's. */
3163 if (sigsetsize
!= sizeof(sigset_t
))
3166 if (copy_from_user(&newset
, unewset
, sizeof(newset
)))
3168 sigdelsetmask(&newset
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
3170 spin_lock_irq(¤t
->sighand
->siglock
);
3171 current
->saved_sigmask
= current
->blocked
;
3172 current
->blocked
= newset
;
3173 recalc_sigpending();
3174 spin_unlock_irq(¤t
->sighand
->siglock
);
3176 current
->state
= TASK_INTERRUPTIBLE
;
3178 set_restore_sigmask();
3179 return -ERESTARTNOHAND
;
3181 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3183 __attribute__((weak
)) const char *arch_vma_name(struct vm_area_struct
*vma
)
3188 void __init
signals_init(void)
3190 sigqueue_cachep
= KMEM_CACHE(sigqueue
, SLAB_PANIC
);
3193 #ifdef CONFIG_KGDB_KDB
3194 #include <linux/kdb.h>
3196 * kdb_send_sig_info - Allows kdb to send signals without exposing
3197 * signal internals. This function checks if the required locks are
3198 * available before calling the main signal code, to avoid kdb
3202 kdb_send_sig_info(struct task_struct
*t
, struct siginfo
*info
)
3204 static struct task_struct
*kdb_prev_t
;
3206 if (!spin_trylock(&t
->sighand
->siglock
)) {
3207 kdb_printf("Can't do kill command now.\n"
3208 "The sigmask lock is held somewhere else in "
3209 "kernel, try again later\n");
3212 spin_unlock(&t
->sighand
->siglock
);
3213 new_t
= kdb_prev_t
!= t
;
3215 if (t
->state
!= TASK_RUNNING
&& new_t
) {
3216 kdb_printf("Process is not RUNNING, sending a signal from "
3217 "kdb risks deadlock\n"
3218 "on the run queue locks. "
3219 "The signal has _not_ been sent.\n"
3220 "Reissue the kill command if you want to risk "
3224 sig
= info
->si_signo
;
3225 if (send_sig_info(sig
, info
, t
))
3226 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3229 kdb_printf("Signal %d is sent to process %d.\n", sig
, t
->pid
);
3231 #endif /* CONFIG_KGDB_KDB */