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
;
1255 local_irq_save(*flags
);
1257 sighand
= rcu_dereference(tsk
->sighand
);
1258 if (unlikely(sighand
== NULL
)) {
1260 local_irq_restore(*flags
);
1264 spin_lock(&sighand
->siglock
);
1265 if (likely(sighand
== tsk
->sighand
)) {
1269 spin_unlock(&sighand
->siglock
);
1271 local_irq_restore(*flags
);
1278 * send signal info to all the members of a group
1280 int group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1285 ret
= check_kill_permission(sig
, info
, p
);
1289 ret
= do_send_sig_info(sig
, info
, p
, true);
1295 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1296 * control characters do (^C, ^Z etc)
1297 * - the caller must hold at least a readlock on tasklist_lock
1299 int __kill_pgrp_info(int sig
, struct siginfo
*info
, struct pid
*pgrp
)
1301 struct task_struct
*p
= NULL
;
1302 int retval
, success
;
1306 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
1307 int err
= group_send_sig_info(sig
, info
, p
);
1310 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
1311 return success
? 0 : retval
;
1314 int kill_pid_info(int sig
, struct siginfo
*info
, struct pid
*pid
)
1317 struct task_struct
*p
;
1321 p
= pid_task(pid
, PIDTYPE_PID
);
1323 error
= group_send_sig_info(sig
, info
, p
);
1324 if (unlikely(error
== -ESRCH
))
1326 * The task was unhashed in between, try again.
1327 * If it is dead, pid_task() will return NULL,
1328 * if we race with de_thread() it will find the
1338 int kill_proc_info(int sig
, struct siginfo
*info
, pid_t pid
)
1342 error
= kill_pid_info(sig
, info
, find_vpid(pid
));
1347 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1348 int kill_pid_info_as_uid(int sig
, struct siginfo
*info
, struct pid
*pid
,
1349 uid_t uid
, uid_t euid
, u32 secid
)
1352 struct task_struct
*p
;
1353 const struct cred
*pcred
;
1354 unsigned long flags
;
1356 if (!valid_signal(sig
))
1360 p
= pid_task(pid
, PIDTYPE_PID
);
1365 pcred
= __task_cred(p
);
1366 if (si_fromuser(info
) &&
1367 euid
!= pcred
->suid
&& euid
!= pcred
->uid
&&
1368 uid
!= pcred
->suid
&& uid
!= pcred
->uid
) {
1372 ret
= security_task_kill(p
, info
, sig
, secid
);
1377 if (lock_task_sighand(p
, &flags
)) {
1378 ret
= __send_signal(sig
, info
, p
, 1, 0);
1379 unlock_task_sighand(p
, &flags
);
1387 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid
);
1390 * kill_something_info() interprets pid in interesting ways just like kill(2).
1392 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1393 * is probably wrong. Should make it like BSD or SYSV.
1396 static int kill_something_info(int sig
, struct siginfo
*info
, pid_t pid
)
1402 ret
= kill_pid_info(sig
, info
, find_vpid(pid
));
1407 read_lock(&tasklist_lock
);
1409 ret
= __kill_pgrp_info(sig
, info
,
1410 pid
? find_vpid(-pid
) : task_pgrp(current
));
1412 int retval
= 0, count
= 0;
1413 struct task_struct
* p
;
1415 for_each_process(p
) {
1416 if (task_pid_vnr(p
) > 1 &&
1417 !same_thread_group(p
, current
)) {
1418 int err
= group_send_sig_info(sig
, info
, p
);
1424 ret
= count
? retval
: -ESRCH
;
1426 read_unlock(&tasklist_lock
);
1432 * These are for backward compatibility with the rest of the kernel source.
1435 int send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1438 * Make sure legacy kernel users don't send in bad values
1439 * (normal paths check this in check_kill_permission).
1441 if (!valid_signal(sig
))
1444 return do_send_sig_info(sig
, info
, p
, false);
1447 #define __si_special(priv) \
1448 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1451 send_sig(int sig
, struct task_struct
*p
, int priv
)
1453 return send_sig_info(sig
, __si_special(priv
), p
);
1457 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..
1469 force_sigsegv(int sig
, struct task_struct
*p
)
1471 if (sig
== SIGSEGV
) {
1472 unsigned long flags
;
1473 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1474 p
->sighand
->action
[sig
- 1].sa
.sa_handler
= SIG_DFL
;
1475 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1477 force_sig(SIGSEGV
, p
);
1481 int kill_pgrp(struct pid
*pid
, int sig
, int priv
)
1485 read_lock(&tasklist_lock
);
1486 ret
= __kill_pgrp_info(sig
, __si_special(priv
), pid
);
1487 read_unlock(&tasklist_lock
);
1491 EXPORT_SYMBOL(kill_pgrp
);
1493 int kill_pid(struct pid
*pid
, int sig
, int priv
)
1495 return kill_pid_info(sig
, __si_special(priv
), pid
);
1497 EXPORT_SYMBOL(kill_pid
);
1500 * These functions support sending signals using preallocated sigqueue
1501 * structures. This is needed "because realtime applications cannot
1502 * afford to lose notifications of asynchronous events, like timer
1503 * expirations or I/O completions". In the case of POSIX Timers
1504 * we allocate the sigqueue structure from the timer_create. If this
1505 * allocation fails we are able to report the failure to the application
1506 * with an EAGAIN error.
1508 struct sigqueue
*sigqueue_alloc(void)
1510 struct sigqueue
*q
= __sigqueue_alloc(-1, current
, GFP_KERNEL
, 0);
1513 q
->flags
|= SIGQUEUE_PREALLOC
;
1518 void sigqueue_free(struct sigqueue
*q
)
1520 unsigned long flags
;
1521 spinlock_t
*lock
= ¤t
->sighand
->siglock
;
1523 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1525 * We must hold ->siglock while testing q->list
1526 * to serialize with collect_signal() or with
1527 * __exit_signal()->flush_sigqueue().
1529 spin_lock_irqsave(lock
, flags
);
1530 q
->flags
&= ~SIGQUEUE_PREALLOC
;
1532 * If it is queued it will be freed when dequeued,
1533 * like the "regular" sigqueue.
1535 if (!list_empty(&q
->list
))
1537 spin_unlock_irqrestore(lock
, flags
);
1543 int send_sigqueue(struct sigqueue
*q
, struct task_struct
*t
, int group
)
1545 int sig
= q
->info
.si_signo
;
1546 struct sigpending
*pending
;
1547 unsigned long flags
;
1550 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1553 if (!likely(lock_task_sighand(t
, &flags
)))
1556 ret
= 1; /* the signal is ignored */
1557 if (!prepare_signal(sig
, t
, 0))
1561 if (unlikely(!list_empty(&q
->list
))) {
1563 * If an SI_TIMER entry is already queue just increment
1564 * the overrun count.
1566 BUG_ON(q
->info
.si_code
!= SI_TIMER
);
1567 q
->info
.si_overrun
++;
1570 q
->info
.si_overrun
= 0;
1572 signalfd_notify(t
, sig
);
1573 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
1574 list_add_tail(&q
->list
, &pending
->list
);
1575 sigaddset(&pending
->signal
, sig
);
1576 complete_signal(sig
, t
, group
);
1578 unlock_task_sighand(t
, &flags
);
1584 * Let a parent know about the death of a child.
1585 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1587 * Returns true if our parent ignored us and so we've switched to
1590 bool do_notify_parent(struct task_struct
*tsk
, int sig
)
1592 struct siginfo info
;
1593 unsigned long flags
;
1594 struct sighand_struct
*psig
;
1595 bool autoreap
= false;
1599 /* do_notify_parent_cldstop should have been called instead. */
1600 BUG_ON(task_is_stopped_or_traced(tsk
));
1602 BUG_ON(!tsk
->ptrace
&&
1603 (tsk
->group_leader
!= tsk
|| !thread_group_empty(tsk
)));
1605 info
.si_signo
= sig
;
1608 * we are under tasklist_lock here so our parent is tied to
1609 * us and cannot exit and release its namespace.
1611 * the only it can is to switch its nsproxy with sys_unshare,
1612 * bu uncharing pid namespaces is not allowed, so we'll always
1613 * see relevant namespace
1615 * write_lock() currently calls preempt_disable() which is the
1616 * same as rcu_read_lock(), but according to Oleg, this is not
1617 * correct to rely on this
1620 info
.si_pid
= task_pid_nr_ns(tsk
, tsk
->parent
->nsproxy
->pid_ns
);
1621 info
.si_uid
= __task_cred(tsk
)->uid
;
1624 info
.si_utime
= cputime_to_clock_t(cputime_add(tsk
->utime
,
1625 tsk
->signal
->utime
));
1626 info
.si_stime
= cputime_to_clock_t(cputime_add(tsk
->stime
,
1627 tsk
->signal
->stime
));
1629 info
.si_status
= tsk
->exit_code
& 0x7f;
1630 if (tsk
->exit_code
& 0x80)
1631 info
.si_code
= CLD_DUMPED
;
1632 else if (tsk
->exit_code
& 0x7f)
1633 info
.si_code
= CLD_KILLED
;
1635 info
.si_code
= CLD_EXITED
;
1636 info
.si_status
= tsk
->exit_code
>> 8;
1639 psig
= tsk
->parent
->sighand
;
1640 spin_lock_irqsave(&psig
->siglock
, flags
);
1641 if (!tsk
->ptrace
&& sig
== SIGCHLD
&&
1642 (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
||
1643 (psig
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDWAIT
))) {
1645 * We are exiting and our parent doesn't care. POSIX.1
1646 * defines special semantics for setting SIGCHLD to SIG_IGN
1647 * or setting the SA_NOCLDWAIT flag: we should be reaped
1648 * automatically and not left for our parent's wait4 call.
1649 * Rather than having the parent do it as a magic kind of
1650 * signal handler, we just set this to tell do_exit that we
1651 * can be cleaned up without becoming a zombie. Note that
1652 * we still call __wake_up_parent in this case, because a
1653 * blocked sys_wait4 might now return -ECHILD.
1655 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1656 * is implementation-defined: we do (if you don't want
1657 * it, just use SIG_IGN instead).
1660 if (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
)
1663 if (valid_signal(sig
) && sig
)
1664 __group_send_sig_info(sig
, &info
, tsk
->parent
);
1665 __wake_up_parent(tsk
, tsk
->parent
);
1666 spin_unlock_irqrestore(&psig
->siglock
, flags
);
1672 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1673 * @tsk: task reporting the state change
1674 * @for_ptracer: the notification is for ptracer
1675 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1677 * Notify @tsk's parent that the stopped/continued state has changed. If
1678 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1679 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1682 * Must be called with tasklist_lock at least read locked.
1684 static void do_notify_parent_cldstop(struct task_struct
*tsk
,
1685 bool for_ptracer
, int why
)
1687 struct siginfo info
;
1688 unsigned long flags
;
1689 struct task_struct
*parent
;
1690 struct sighand_struct
*sighand
;
1693 parent
= tsk
->parent
;
1695 tsk
= tsk
->group_leader
;
1696 parent
= tsk
->real_parent
;
1699 info
.si_signo
= SIGCHLD
;
1702 * see comment in do_notify_parent() about the following 4 lines
1705 info
.si_pid
= task_pid_nr_ns(tsk
, parent
->nsproxy
->pid_ns
);
1706 info
.si_uid
= __task_cred(tsk
)->uid
;
1709 info
.si_utime
= cputime_to_clock_t(tsk
->utime
);
1710 info
.si_stime
= cputime_to_clock_t(tsk
->stime
);
1715 info
.si_status
= SIGCONT
;
1718 info
.si_status
= tsk
->signal
->group_exit_code
& 0x7f;
1721 info
.si_status
= tsk
->exit_code
& 0x7f;
1727 sighand
= parent
->sighand
;
1728 spin_lock_irqsave(&sighand
->siglock
, flags
);
1729 if (sighand
->action
[SIGCHLD
-1].sa
.sa_handler
!= SIG_IGN
&&
1730 !(sighand
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDSTOP
))
1731 __group_send_sig_info(SIGCHLD
, &info
, parent
);
1733 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1735 __wake_up_parent(tsk
, parent
);
1736 spin_unlock_irqrestore(&sighand
->siglock
, flags
);
1739 static inline int may_ptrace_stop(void)
1741 if (!likely(current
->ptrace
))
1744 * Are we in the middle of do_coredump?
1745 * If so and our tracer is also part of the coredump stopping
1746 * is a deadlock situation, and pointless because our tracer
1747 * is dead so don't allow us to stop.
1748 * If SIGKILL was already sent before the caller unlocked
1749 * ->siglock we must see ->core_state != NULL. Otherwise it
1750 * is safe to enter schedule().
1752 if (unlikely(current
->mm
->core_state
) &&
1753 unlikely(current
->mm
== current
->parent
->mm
))
1760 * Return non-zero if there is a SIGKILL that should be waking us up.
1761 * Called with the siglock held.
1763 static int sigkill_pending(struct task_struct
*tsk
)
1765 return sigismember(&tsk
->pending
.signal
, SIGKILL
) ||
1766 sigismember(&tsk
->signal
->shared_pending
.signal
, SIGKILL
);
1770 * This must be called with current->sighand->siglock held.
1772 * This should be the path for all ptrace stops.
1773 * We always set current->last_siginfo while stopped here.
1774 * That makes it a way to test a stopped process for
1775 * being ptrace-stopped vs being job-control-stopped.
1777 * If we actually decide not to stop at all because the tracer
1778 * is gone, we keep current->exit_code unless clear_code.
1780 static void ptrace_stop(int exit_code
, int why
, int clear_code
, siginfo_t
*info
)
1781 __releases(¤t
->sighand
->siglock
)
1782 __acquires(¤t
->sighand
->siglock
)
1784 bool gstop_done
= false;
1786 if (arch_ptrace_stop_needed(exit_code
, info
)) {
1788 * The arch code has something special to do before a
1789 * ptrace stop. This is allowed to block, e.g. for faults
1790 * on user stack pages. We can't keep the siglock while
1791 * calling arch_ptrace_stop, so we must release it now.
1792 * To preserve proper semantics, we must do this before
1793 * any signal bookkeeping like checking group_stop_count.
1794 * Meanwhile, a SIGKILL could come in before we retake the
1795 * siglock. That must prevent us from sleeping in TASK_TRACED.
1796 * So after regaining the lock, we must check for SIGKILL.
1798 spin_unlock_irq(¤t
->sighand
->siglock
);
1799 arch_ptrace_stop(exit_code
, info
);
1800 spin_lock_irq(¤t
->sighand
->siglock
);
1801 if (sigkill_pending(current
))
1806 * We're committing to trapping. TRACED should be visible before
1807 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1808 * Also, transition to TRACED and updates to ->jobctl should be
1809 * atomic with respect to siglock and should be done after the arch
1810 * hook as siglock is released and regrabbed across it.
1812 set_current_state(TASK_TRACED
);
1814 current
->last_siginfo
= info
;
1815 current
->exit_code
= exit_code
;
1818 * If @why is CLD_STOPPED, we're trapping to participate in a group
1819 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1820 * across siglock relocks since INTERRUPT was scheduled, PENDING
1821 * could be clear now. We act as if SIGCONT is received after
1822 * TASK_TRACED is entered - ignore it.
1824 if (why
== CLD_STOPPED
&& (current
->jobctl
& JOBCTL_STOP_PENDING
))
1825 gstop_done
= task_participate_group_stop(current
);
1827 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1828 task_clear_jobctl_pending(current
, JOBCTL_TRAP_STOP
);
1829 if (info
&& info
->si_code
>> 8 == PTRACE_EVENT_STOP
)
1830 task_clear_jobctl_pending(current
, JOBCTL_TRAP_NOTIFY
);
1832 /* entering a trap, clear TRAPPING */
1833 task_clear_jobctl_trapping(current
);
1835 spin_unlock_irq(¤t
->sighand
->siglock
);
1836 read_lock(&tasklist_lock
);
1837 if (may_ptrace_stop()) {
1839 * Notify parents of the stop.
1841 * While ptraced, there are two parents - the ptracer and
1842 * the real_parent of the group_leader. The ptracer should
1843 * know about every stop while the real parent is only
1844 * interested in the completion of group stop. The states
1845 * for the two don't interact with each other. Notify
1846 * separately unless they're gonna be duplicates.
1848 do_notify_parent_cldstop(current
, true, why
);
1849 if (gstop_done
&& ptrace_reparented(current
))
1850 do_notify_parent_cldstop(current
, false, why
);
1853 * Don't want to allow preemption here, because
1854 * sys_ptrace() needs this task to be inactive.
1856 * XXX: implement read_unlock_no_resched().
1859 read_unlock(&tasklist_lock
);
1860 preempt_enable_no_resched();
1864 * By the time we got the lock, our tracer went away.
1865 * Don't drop the lock yet, another tracer may come.
1867 * If @gstop_done, the ptracer went away between group stop
1868 * completion and here. During detach, it would have set
1869 * JOBCTL_STOP_PENDING on us and we'll re-enter
1870 * TASK_STOPPED in do_signal_stop() on return, so notifying
1871 * the real parent of the group stop completion is enough.
1874 do_notify_parent_cldstop(current
, false, why
);
1876 __set_current_state(TASK_RUNNING
);
1878 current
->exit_code
= 0;
1879 read_unlock(&tasklist_lock
);
1883 * While in TASK_TRACED, we were considered "frozen enough".
1884 * Now that we woke up, it's crucial if we're supposed to be
1885 * frozen that we freeze now before running anything substantial.
1890 * We are back. Now reacquire the siglock before touching
1891 * last_siginfo, so that we are sure to have synchronized with
1892 * any signal-sending on another CPU that wants to examine it.
1894 spin_lock_irq(¤t
->sighand
->siglock
);
1895 current
->last_siginfo
= NULL
;
1897 /* LISTENING can be set only during STOP traps, clear it */
1898 current
->jobctl
&= ~JOBCTL_LISTENING
;
1901 * Queued signals ignored us while we were stopped for tracing.
1902 * So check for any that we should take before resuming user mode.
1903 * This sets TIF_SIGPENDING, but never clears it.
1905 recalc_sigpending_tsk(current
);
1908 static void ptrace_do_notify(int signr
, int exit_code
, int why
)
1912 memset(&info
, 0, sizeof info
);
1913 info
.si_signo
= signr
;
1914 info
.si_code
= exit_code
;
1915 info
.si_pid
= task_pid_vnr(current
);
1916 info
.si_uid
= current_uid();
1918 /* Let the debugger run. */
1919 ptrace_stop(exit_code
, why
, 1, &info
);
1922 void ptrace_notify(int exit_code
)
1924 BUG_ON((exit_code
& (0x7f | ~0xffff)) != SIGTRAP
);
1926 spin_lock_irq(¤t
->sighand
->siglock
);
1927 ptrace_do_notify(SIGTRAP
, exit_code
, CLD_TRAPPED
);
1928 spin_unlock_irq(¤t
->sighand
->siglock
);
1932 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1933 * @signr: signr causing group stop if initiating
1935 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1936 * and participate in it. If already set, participate in the existing
1937 * group stop. If participated in a group stop (and thus slept), %true is
1938 * returned with siglock released.
1940 * If ptraced, this function doesn't handle stop itself. Instead,
1941 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1942 * untouched. The caller must ensure that INTERRUPT trap handling takes
1943 * places afterwards.
1946 * Must be called with @current->sighand->siglock held, which is released
1950 * %false if group stop is already cancelled or ptrace trap is scheduled.
1951 * %true if participated in group stop.
1953 static bool do_signal_stop(int signr
)
1954 __releases(¤t
->sighand
->siglock
)
1956 struct signal_struct
*sig
= current
->signal
;
1958 if (!(current
->jobctl
& JOBCTL_STOP_PENDING
)) {
1959 unsigned int gstop
= JOBCTL_STOP_PENDING
| JOBCTL_STOP_CONSUME
;
1960 struct task_struct
*t
;
1962 /* signr will be recorded in task->jobctl for retries */
1963 WARN_ON_ONCE(signr
& ~JOBCTL_STOP_SIGMASK
);
1965 if (!likely(current
->jobctl
& JOBCTL_STOP_DEQUEUED
) ||
1966 unlikely(signal_group_exit(sig
)))
1969 * There is no group stop already in progress. We must
1972 * While ptraced, a task may be resumed while group stop is
1973 * still in effect and then receive a stop signal and
1974 * initiate another group stop. This deviates from the
1975 * usual behavior as two consecutive stop signals can't
1976 * cause two group stops when !ptraced. That is why we
1977 * also check !task_is_stopped(t) below.
1979 * The condition can be distinguished by testing whether
1980 * SIGNAL_STOP_STOPPED is already set. Don't generate
1981 * group_exit_code in such case.
1983 * This is not necessary for SIGNAL_STOP_CONTINUED because
1984 * an intervening stop signal is required to cause two
1985 * continued events regardless of ptrace.
1987 if (!(sig
->flags
& SIGNAL_STOP_STOPPED
))
1988 sig
->group_exit_code
= signr
;
1990 sig
->group_stop_count
= 0;
1992 if (task_set_jobctl_pending(current
, signr
| gstop
))
1993 sig
->group_stop_count
++;
1995 for (t
= next_thread(current
); t
!= current
;
1996 t
= next_thread(t
)) {
1998 * Setting state to TASK_STOPPED for a group
1999 * stop is always done with the siglock held,
2000 * so this check has no races.
2002 if (!task_is_stopped(t
) &&
2003 task_set_jobctl_pending(t
, signr
| gstop
)) {
2004 sig
->group_stop_count
++;
2005 if (likely(!(t
->ptrace
& PT_SEIZED
)))
2006 signal_wake_up(t
, 0);
2008 ptrace_trap_notify(t
);
2013 if (likely(!current
->ptrace
)) {
2017 * If there are no other threads in the group, or if there
2018 * is a group stop in progress and we are the last to stop,
2019 * report to the parent.
2021 if (task_participate_group_stop(current
))
2022 notify
= CLD_STOPPED
;
2024 __set_current_state(TASK_STOPPED
);
2025 spin_unlock_irq(¤t
->sighand
->siglock
);
2028 * Notify the parent of the group stop completion. Because
2029 * we're not holding either the siglock or tasklist_lock
2030 * here, ptracer may attach inbetween; however, this is for
2031 * group stop and should always be delivered to the real
2032 * parent of the group leader. The new ptracer will get
2033 * its notification when this task transitions into
2037 read_lock(&tasklist_lock
);
2038 do_notify_parent_cldstop(current
, false, notify
);
2039 read_unlock(&tasklist_lock
);
2042 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2047 * While ptraced, group stop is handled by STOP trap.
2048 * Schedule it and let the caller deal with it.
2050 task_set_jobctl_pending(current
, JOBCTL_TRAP_STOP
);
2056 * do_jobctl_trap - take care of ptrace jobctl traps
2058 * When PT_SEIZED, it's used for both group stop and explicit
2059 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2060 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2061 * the stop signal; otherwise, %SIGTRAP.
2063 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2064 * number as exit_code and no siginfo.
2067 * Must be called with @current->sighand->siglock held, which may be
2068 * released and re-acquired before returning with intervening sleep.
2070 static void do_jobctl_trap(void)
2072 struct signal_struct
*signal
= current
->signal
;
2073 int signr
= current
->jobctl
& JOBCTL_STOP_SIGMASK
;
2075 if (current
->ptrace
& PT_SEIZED
) {
2076 if (!signal
->group_stop_count
&&
2077 !(signal
->flags
& SIGNAL_STOP_STOPPED
))
2079 WARN_ON_ONCE(!signr
);
2080 ptrace_do_notify(signr
, signr
| (PTRACE_EVENT_STOP
<< 8),
2083 WARN_ON_ONCE(!signr
);
2084 ptrace_stop(signr
, CLD_STOPPED
, 0, NULL
);
2085 current
->exit_code
= 0;
2089 static int ptrace_signal(int signr
, siginfo_t
*info
,
2090 struct pt_regs
*regs
, void *cookie
)
2092 ptrace_signal_deliver(regs
, cookie
);
2094 * We do not check sig_kernel_stop(signr) but set this marker
2095 * unconditionally because we do not know whether debugger will
2096 * change signr. This flag has no meaning unless we are going
2097 * to stop after return from ptrace_stop(). In this case it will
2098 * be checked in do_signal_stop(), we should only stop if it was
2099 * not cleared by SIGCONT while we were sleeping. See also the
2100 * comment in dequeue_signal().
2102 current
->jobctl
|= JOBCTL_STOP_DEQUEUED
;
2103 ptrace_stop(signr
, CLD_TRAPPED
, 0, info
);
2105 /* We're back. Did the debugger cancel the sig? */
2106 signr
= current
->exit_code
;
2110 current
->exit_code
= 0;
2113 * Update the siginfo structure if the signal has
2114 * changed. If the debugger wanted something
2115 * specific in the siginfo structure then it should
2116 * have updated *info via PTRACE_SETSIGINFO.
2118 if (signr
!= info
->si_signo
) {
2119 info
->si_signo
= signr
;
2121 info
->si_code
= SI_USER
;
2122 info
->si_pid
= task_pid_vnr(current
->parent
);
2123 info
->si_uid
= task_uid(current
->parent
);
2126 /* If the (new) signal is now blocked, requeue it. */
2127 if (sigismember(¤t
->blocked
, signr
)) {
2128 specific_send_sig_info(signr
, info
, current
);
2135 int get_signal_to_deliver(siginfo_t
*info
, struct k_sigaction
*return_ka
,
2136 struct pt_regs
*regs
, void *cookie
)
2138 struct sighand_struct
*sighand
= current
->sighand
;
2139 struct signal_struct
*signal
= current
->signal
;
2144 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2145 * While in TASK_STOPPED, we were considered "frozen enough".
2146 * Now that we woke up, it's crucial if we're supposed to be
2147 * frozen that we freeze now before running anything substantial.
2151 spin_lock_irq(&sighand
->siglock
);
2153 * Every stopped thread goes here after wakeup. Check to see if
2154 * we should notify the parent, prepare_signal(SIGCONT) encodes
2155 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2157 if (unlikely(signal
->flags
& SIGNAL_CLD_MASK
)) {
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
);
2178 do_notify_parent_cldstop(current
, false, why
);
2180 if (ptrace_reparented(current
->group_leader
))
2181 do_notify_parent_cldstop(current
->group_leader
,
2183 read_unlock(&tasklist_lock
);
2189 struct k_sigaction
*ka
;
2191 if (unlikely(current
->jobctl
& JOBCTL_STOP_PENDING
) &&
2195 if (unlikely(current
->jobctl
& JOBCTL_TRAP_MASK
)) {
2197 spin_unlock_irq(&sighand
->siglock
);
2201 signr
= dequeue_signal(current
, ¤t
->blocked
, info
);
2204 break; /* will return 0 */
2206 if (unlikely(current
->ptrace
) && signr
!= SIGKILL
) {
2207 signr
= ptrace_signal(signr
, info
,
2213 ka
= &sighand
->action
[signr
-1];
2215 /* Trace actually delivered signals. */
2216 trace_signal_deliver(signr
, info
, ka
);
2218 if (ka
->sa
.sa_handler
== SIG_IGN
) /* Do nothing. */
2220 if (ka
->sa
.sa_handler
!= SIG_DFL
) {
2221 /* Run the handler. */
2224 if (ka
->sa
.sa_flags
& SA_ONESHOT
)
2225 ka
->sa
.sa_handler
= SIG_DFL
;
2227 break; /* will return non-zero "signr" value */
2231 * Now we are doing the default action for this signal.
2233 if (sig_kernel_ignore(signr
)) /* Default is nothing. */
2237 * Global init gets no signals it doesn't want.
2238 * Container-init gets no signals it doesn't want from same
2241 * Note that if global/container-init sees a sig_kernel_only()
2242 * signal here, the signal must have been generated internally
2243 * or must have come from an ancestor namespace. In either
2244 * case, the signal cannot be dropped.
2246 if (unlikely(signal
->flags
& SIGNAL_UNKILLABLE
) &&
2247 !sig_kernel_only(signr
))
2250 if (sig_kernel_stop(signr
)) {
2252 * The default action is to stop all threads in
2253 * the thread group. The job control signals
2254 * do nothing in an orphaned pgrp, but SIGSTOP
2255 * always works. Note that siglock needs to be
2256 * dropped during the call to is_orphaned_pgrp()
2257 * because of lock ordering with tasklist_lock.
2258 * This allows an intervening SIGCONT to be posted.
2259 * We need to check for that and bail out if necessary.
2261 if (signr
!= SIGSTOP
) {
2262 spin_unlock_irq(&sighand
->siglock
);
2264 /* signals can be posted during this window */
2266 if (is_current_pgrp_orphaned())
2269 spin_lock_irq(&sighand
->siglock
);
2272 if (likely(do_signal_stop(info
->si_signo
))) {
2273 /* It released the siglock. */
2278 * We didn't actually stop, due to a race
2279 * with SIGCONT or something like that.
2284 spin_unlock_irq(&sighand
->siglock
);
2287 * Anything else is fatal, maybe with a core dump.
2289 current
->flags
|= PF_SIGNALED
;
2291 if (sig_kernel_coredump(signr
)) {
2292 if (print_fatal_signals
)
2293 print_fatal_signal(regs
, info
->si_signo
);
2295 * If it was able to dump core, this kills all
2296 * other threads in the group and synchronizes with
2297 * their demise. If we lost the race with another
2298 * thread getting here, it set group_exit_code
2299 * first and our do_group_exit call below will use
2300 * that value and ignore the one we pass it.
2302 do_coredump(info
->si_signo
, info
->si_signo
, regs
);
2306 * Death signals, no core dump.
2308 do_group_exit(info
->si_signo
);
2311 spin_unlock_irq(&sighand
->siglock
);
2316 * It could be that complete_signal() picked us to notify about the
2317 * group-wide signal. Other threads should be notified now to take
2318 * the shared signals in @which since we will not.
2320 static void retarget_shared_pending(struct task_struct
*tsk
, sigset_t
*which
)
2323 struct task_struct
*t
;
2325 sigandsets(&retarget
, &tsk
->signal
->shared_pending
.signal
, which
);
2326 if (sigisemptyset(&retarget
))
2330 while_each_thread(tsk
, t
) {
2331 if (t
->flags
& PF_EXITING
)
2334 if (!has_pending_signals(&retarget
, &t
->blocked
))
2336 /* Remove the signals this thread can handle. */
2337 sigandsets(&retarget
, &retarget
, &t
->blocked
);
2339 if (!signal_pending(t
))
2340 signal_wake_up(t
, 0);
2342 if (sigisemptyset(&retarget
))
2347 void exit_signals(struct task_struct
*tsk
)
2352 if (thread_group_empty(tsk
) || signal_group_exit(tsk
->signal
)) {
2353 tsk
->flags
|= PF_EXITING
;
2357 spin_lock_irq(&tsk
->sighand
->siglock
);
2359 * From now this task is not visible for group-wide signals,
2360 * see wants_signal(), do_signal_stop().
2362 tsk
->flags
|= PF_EXITING
;
2363 if (!signal_pending(tsk
))
2366 unblocked
= tsk
->blocked
;
2367 signotset(&unblocked
);
2368 retarget_shared_pending(tsk
, &unblocked
);
2370 if (unlikely(tsk
->jobctl
& JOBCTL_STOP_PENDING
) &&
2371 task_participate_group_stop(tsk
))
2372 group_stop
= CLD_STOPPED
;
2374 spin_unlock_irq(&tsk
->sighand
->siglock
);
2377 * If group stop has completed, deliver the notification. This
2378 * should always go to the real parent of the group leader.
2380 if (unlikely(group_stop
)) {
2381 read_lock(&tasklist_lock
);
2382 do_notify_parent_cldstop(tsk
, false, group_stop
);
2383 read_unlock(&tasklist_lock
);
2387 EXPORT_SYMBOL(recalc_sigpending
);
2388 EXPORT_SYMBOL_GPL(dequeue_signal
);
2389 EXPORT_SYMBOL(flush_signals
);
2390 EXPORT_SYMBOL(force_sig
);
2391 EXPORT_SYMBOL(send_sig
);
2392 EXPORT_SYMBOL(send_sig_info
);
2393 EXPORT_SYMBOL(sigprocmask
);
2394 EXPORT_SYMBOL(block_all_signals
);
2395 EXPORT_SYMBOL(unblock_all_signals
);
2399 * System call entry points.
2403 * sys_restart_syscall - restart a system call
2405 SYSCALL_DEFINE0(restart_syscall
)
2407 struct restart_block
*restart
= ¤t_thread_info()->restart_block
;
2408 return restart
->fn(restart
);
2411 long do_no_restart_syscall(struct restart_block
*param
)
2416 static void __set_task_blocked(struct task_struct
*tsk
, const sigset_t
*newset
)
2418 if (signal_pending(tsk
) && !thread_group_empty(tsk
)) {
2419 sigset_t newblocked
;
2420 /* A set of now blocked but previously unblocked signals. */
2421 sigandnsets(&newblocked
, newset
, ¤t
->blocked
);
2422 retarget_shared_pending(tsk
, &newblocked
);
2424 tsk
->blocked
= *newset
;
2425 recalc_sigpending();
2429 * set_current_blocked - change current->blocked mask
2432 * It is wrong to change ->blocked directly, this helper should be used
2433 * to ensure the process can't miss a shared signal we are going to block.
2435 void set_current_blocked(const sigset_t
*newset
)
2437 struct task_struct
*tsk
= current
;
2439 spin_lock_irq(&tsk
->sighand
->siglock
);
2440 __set_task_blocked(tsk
, newset
);
2441 spin_unlock_irq(&tsk
->sighand
->siglock
);
2445 * This is also useful for kernel threads that want to temporarily
2446 * (or permanently) block certain signals.
2448 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2449 * interface happily blocks "unblockable" signals like SIGKILL
2452 int sigprocmask(int how
, sigset_t
*set
, sigset_t
*oldset
)
2454 struct task_struct
*tsk
= current
;
2457 /* Lockless, only current can change ->blocked, never from irq */
2459 *oldset
= tsk
->blocked
;
2463 sigorsets(&newset
, &tsk
->blocked
, set
);
2466 sigandnsets(&newset
, &tsk
->blocked
, set
);
2475 set_current_blocked(&newset
);
2480 * sys_rt_sigprocmask - change the list of currently blocked signals
2481 * @how: whether to add, remove, or set signals
2482 * @nset: stores pending signals
2483 * @oset: previous value of signal mask if non-null
2484 * @sigsetsize: size of sigset_t type
2486 SYSCALL_DEFINE4(rt_sigprocmask
, int, how
, sigset_t __user
*, nset
,
2487 sigset_t __user
*, oset
, size_t, sigsetsize
)
2489 sigset_t old_set
, new_set
;
2492 /* XXX: Don't preclude handling different sized sigset_t's. */
2493 if (sigsetsize
!= sizeof(sigset_t
))
2496 old_set
= current
->blocked
;
2499 if (copy_from_user(&new_set
, nset
, sizeof(sigset_t
)))
2501 sigdelsetmask(&new_set
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2503 error
= sigprocmask(how
, &new_set
, NULL
);
2509 if (copy_to_user(oset
, &old_set
, sizeof(sigset_t
)))
2516 long do_sigpending(void __user
*set
, unsigned long sigsetsize
)
2518 long error
= -EINVAL
;
2521 if (sigsetsize
> sizeof(sigset_t
))
2524 spin_lock_irq(¤t
->sighand
->siglock
);
2525 sigorsets(&pending
, ¤t
->pending
.signal
,
2526 ¤t
->signal
->shared_pending
.signal
);
2527 spin_unlock_irq(¤t
->sighand
->siglock
);
2529 /* Outside the lock because only this thread touches it. */
2530 sigandsets(&pending
, ¤t
->blocked
, &pending
);
2533 if (!copy_to_user(set
, &pending
, sigsetsize
))
2541 * sys_rt_sigpending - examine a pending signal that has been raised
2543 * @set: stores pending signals
2544 * @sigsetsize: size of sigset_t type or larger
2546 SYSCALL_DEFINE2(rt_sigpending
, sigset_t __user
*, set
, size_t, sigsetsize
)
2548 return do_sigpending(set
, sigsetsize
);
2551 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2553 int copy_siginfo_to_user(siginfo_t __user
*to
, siginfo_t
*from
)
2557 if (!access_ok (VERIFY_WRITE
, to
, sizeof(siginfo_t
)))
2559 if (from
->si_code
< 0)
2560 return __copy_to_user(to
, from
, sizeof(siginfo_t
))
2563 * If you change siginfo_t structure, please be sure
2564 * this code is fixed accordingly.
2565 * Please remember to update the signalfd_copyinfo() function
2566 * inside fs/signalfd.c too, in case siginfo_t changes.
2567 * It should never copy any pad contained in the structure
2568 * to avoid security leaks, but must copy the generic
2569 * 3 ints plus the relevant union member.
2571 err
= __put_user(from
->si_signo
, &to
->si_signo
);
2572 err
|= __put_user(from
->si_errno
, &to
->si_errno
);
2573 err
|= __put_user((short)from
->si_code
, &to
->si_code
);
2574 switch (from
->si_code
& __SI_MASK
) {
2576 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2577 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2580 err
|= __put_user(from
->si_tid
, &to
->si_tid
);
2581 err
|= __put_user(from
->si_overrun
, &to
->si_overrun
);
2582 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2585 err
|= __put_user(from
->si_band
, &to
->si_band
);
2586 err
|= __put_user(from
->si_fd
, &to
->si_fd
);
2589 err
|= __put_user(from
->si_addr
, &to
->si_addr
);
2590 #ifdef __ARCH_SI_TRAPNO
2591 err
|= __put_user(from
->si_trapno
, &to
->si_trapno
);
2593 #ifdef BUS_MCEERR_AO
2595 * Other callers might not initialize the si_lsb field,
2596 * so check explicitly for the right codes here.
2598 if (from
->si_code
== BUS_MCEERR_AR
|| from
->si_code
== BUS_MCEERR_AO
)
2599 err
|= __put_user(from
->si_addr_lsb
, &to
->si_addr_lsb
);
2603 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2604 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2605 err
|= __put_user(from
->si_status
, &to
->si_status
);
2606 err
|= __put_user(from
->si_utime
, &to
->si_utime
);
2607 err
|= __put_user(from
->si_stime
, &to
->si_stime
);
2609 case __SI_RT
: /* This is not generated by the kernel as of now. */
2610 case __SI_MESGQ
: /* But this is */
2611 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2612 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2613 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2615 default: /* this is just in case for now ... */
2616 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2617 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2626 * do_sigtimedwait - wait for queued signals specified in @which
2627 * @which: queued signals to wait for
2628 * @info: if non-null, the signal's siginfo is returned here
2629 * @ts: upper bound on process time suspension
2631 int do_sigtimedwait(const sigset_t
*which
, siginfo_t
*info
,
2632 const struct timespec
*ts
)
2634 struct task_struct
*tsk
= current
;
2635 long timeout
= MAX_SCHEDULE_TIMEOUT
;
2636 sigset_t mask
= *which
;
2640 if (!timespec_valid(ts
))
2642 timeout
= timespec_to_jiffies(ts
);
2644 * We can be close to the next tick, add another one
2645 * to ensure we will wait at least the time asked for.
2647 if (ts
->tv_sec
|| ts
->tv_nsec
)
2652 * Invert the set of allowed signals to get those we want to block.
2654 sigdelsetmask(&mask
, sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2657 spin_lock_irq(&tsk
->sighand
->siglock
);
2658 sig
= dequeue_signal(tsk
, &mask
, info
);
2659 if (!sig
&& timeout
) {
2661 * None ready, temporarily unblock those we're interested
2662 * while we are sleeping in so that we'll be awakened when
2663 * they arrive. Unblocking is always fine, we can avoid
2664 * set_current_blocked().
2666 tsk
->real_blocked
= tsk
->blocked
;
2667 sigandsets(&tsk
->blocked
, &tsk
->blocked
, &mask
);
2668 recalc_sigpending();
2669 spin_unlock_irq(&tsk
->sighand
->siglock
);
2671 timeout
= schedule_timeout_interruptible(timeout
);
2673 spin_lock_irq(&tsk
->sighand
->siglock
);
2674 __set_task_blocked(tsk
, &tsk
->real_blocked
);
2675 siginitset(&tsk
->real_blocked
, 0);
2676 sig
= dequeue_signal(tsk
, &mask
, info
);
2678 spin_unlock_irq(&tsk
->sighand
->siglock
);
2682 return timeout
? -EINTR
: -EAGAIN
;
2686 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2688 * @uthese: queued signals to wait for
2689 * @uinfo: if non-null, the signal's siginfo is returned here
2690 * @uts: upper bound on process time suspension
2691 * @sigsetsize: size of sigset_t type
2693 SYSCALL_DEFINE4(rt_sigtimedwait
, const sigset_t __user
*, uthese
,
2694 siginfo_t __user
*, uinfo
, const struct timespec __user
*, uts
,
2702 /* XXX: Don't preclude handling different sized sigset_t's. */
2703 if (sigsetsize
!= sizeof(sigset_t
))
2706 if (copy_from_user(&these
, uthese
, sizeof(these
)))
2710 if (copy_from_user(&ts
, uts
, sizeof(ts
)))
2714 ret
= do_sigtimedwait(&these
, &info
, uts
? &ts
: NULL
);
2716 if (ret
> 0 && uinfo
) {
2717 if (copy_siginfo_to_user(uinfo
, &info
))
2725 * sys_kill - send a signal to a process
2726 * @pid: the PID of the process
2727 * @sig: signal to be sent
2729 SYSCALL_DEFINE2(kill
, pid_t
, pid
, int, sig
)
2731 struct siginfo info
;
2733 info
.si_signo
= sig
;
2735 info
.si_code
= SI_USER
;
2736 info
.si_pid
= task_tgid_vnr(current
);
2737 info
.si_uid
= current_uid();
2739 return kill_something_info(sig
, &info
, pid
);
2743 do_send_specific(pid_t tgid
, pid_t pid
, int sig
, struct siginfo
*info
)
2745 struct task_struct
*p
;
2749 p
= find_task_by_vpid(pid
);
2750 if (p
&& (tgid
<= 0 || task_tgid_vnr(p
) == tgid
)) {
2751 error
= check_kill_permission(sig
, info
, p
);
2753 * The null signal is a permissions and process existence
2754 * probe. No signal is actually delivered.
2756 if (!error
&& sig
) {
2757 error
= do_send_sig_info(sig
, info
, p
, false);
2759 * If lock_task_sighand() failed we pretend the task
2760 * dies after receiving the signal. The window is tiny,
2761 * and the signal is private anyway.
2763 if (unlikely(error
== -ESRCH
))
2772 static int do_tkill(pid_t tgid
, pid_t pid
, int sig
)
2774 struct siginfo info
;
2776 info
.si_signo
= sig
;
2778 info
.si_code
= SI_TKILL
;
2779 info
.si_pid
= task_tgid_vnr(current
);
2780 info
.si_uid
= current_uid();
2782 return do_send_specific(tgid
, pid
, sig
, &info
);
2786 * sys_tgkill - send signal to one specific thread
2787 * @tgid: the thread group ID of the thread
2788 * @pid: the PID of the thread
2789 * @sig: signal to be sent
2791 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2792 * exists but it's not belonging to the target process anymore. This
2793 * method solves the problem of threads exiting and PIDs getting reused.
2795 SYSCALL_DEFINE3(tgkill
, pid_t
, tgid
, pid_t
, pid
, int, sig
)
2797 /* This is only valid for single tasks */
2798 if (pid
<= 0 || tgid
<= 0)
2801 return do_tkill(tgid
, pid
, sig
);
2805 * sys_tkill - send signal to one specific task
2806 * @pid: the PID of the task
2807 * @sig: signal to be sent
2809 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2811 SYSCALL_DEFINE2(tkill
, pid_t
, pid
, int, sig
)
2813 /* This is only valid for single tasks */
2817 return do_tkill(0, pid
, sig
);
2821 * sys_rt_sigqueueinfo - send signal information to a signal
2822 * @pid: the PID of the thread
2823 * @sig: signal to be sent
2824 * @uinfo: signal info to be sent
2826 SYSCALL_DEFINE3(rt_sigqueueinfo
, pid_t
, pid
, int, sig
,
2827 siginfo_t __user
*, uinfo
)
2831 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
2834 /* Not even root can pretend to send signals from the kernel.
2835 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2837 if (info
.si_code
>= 0 || info
.si_code
== SI_TKILL
) {
2838 /* We used to allow any < 0 si_code */
2839 WARN_ON_ONCE(info
.si_code
< 0);
2842 info
.si_signo
= sig
;
2844 /* POSIX.1b doesn't mention process groups. */
2845 return kill_proc_info(sig
, &info
, pid
);
2848 long do_rt_tgsigqueueinfo(pid_t tgid
, pid_t pid
, int sig
, siginfo_t
*info
)
2850 /* This is only valid for single tasks */
2851 if (pid
<= 0 || tgid
<= 0)
2854 /* Not even root can pretend to send signals from the kernel.
2855 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2857 if (info
->si_code
>= 0 || info
->si_code
== SI_TKILL
) {
2858 /* We used to allow any < 0 si_code */
2859 WARN_ON_ONCE(info
->si_code
< 0);
2862 info
->si_signo
= sig
;
2864 return do_send_specific(tgid
, pid
, sig
, info
);
2867 SYSCALL_DEFINE4(rt_tgsigqueueinfo
, pid_t
, tgid
, pid_t
, pid
, int, sig
,
2868 siginfo_t __user
*, uinfo
)
2872 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
2875 return do_rt_tgsigqueueinfo(tgid
, pid
, sig
, &info
);
2878 int do_sigaction(int sig
, struct k_sigaction
*act
, struct k_sigaction
*oact
)
2880 struct task_struct
*t
= current
;
2881 struct k_sigaction
*k
;
2884 if (!valid_signal(sig
) || sig
< 1 || (act
&& sig_kernel_only(sig
)))
2887 k
= &t
->sighand
->action
[sig
-1];
2889 spin_lock_irq(¤t
->sighand
->siglock
);
2894 sigdelsetmask(&act
->sa
.sa_mask
,
2895 sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2899 * "Setting a signal action to SIG_IGN for a signal that is
2900 * pending shall cause the pending signal to be discarded,
2901 * whether or not it is blocked."
2903 * "Setting a signal action to SIG_DFL for a signal that is
2904 * pending and whose default action is to ignore the signal
2905 * (for example, SIGCHLD), shall cause the pending signal to
2906 * be discarded, whether or not it is blocked"
2908 if (sig_handler_ignored(sig_handler(t
, sig
), sig
)) {
2910 sigaddset(&mask
, sig
);
2911 rm_from_queue_full(&mask
, &t
->signal
->shared_pending
);
2913 rm_from_queue_full(&mask
, &t
->pending
);
2915 } while (t
!= current
);
2919 spin_unlock_irq(¤t
->sighand
->siglock
);
2924 do_sigaltstack (const stack_t __user
*uss
, stack_t __user
*uoss
, unsigned long sp
)
2929 oss
.ss_sp
= (void __user
*) current
->sas_ss_sp
;
2930 oss
.ss_size
= current
->sas_ss_size
;
2931 oss
.ss_flags
= sas_ss_flags(sp
);
2939 if (!access_ok(VERIFY_READ
, uss
, sizeof(*uss
)))
2941 error
= __get_user(ss_sp
, &uss
->ss_sp
) |
2942 __get_user(ss_flags
, &uss
->ss_flags
) |
2943 __get_user(ss_size
, &uss
->ss_size
);
2948 if (on_sig_stack(sp
))
2953 * Note - this code used to test ss_flags incorrectly:
2954 * old code may have been written using ss_flags==0
2955 * to mean ss_flags==SS_ONSTACK (as this was the only
2956 * way that worked) - this fix preserves that older
2959 if (ss_flags
!= SS_DISABLE
&& ss_flags
!= SS_ONSTACK
&& ss_flags
!= 0)
2962 if (ss_flags
== SS_DISABLE
) {
2967 if (ss_size
< MINSIGSTKSZ
)
2971 current
->sas_ss_sp
= (unsigned long) ss_sp
;
2972 current
->sas_ss_size
= ss_size
;
2978 if (!access_ok(VERIFY_WRITE
, uoss
, sizeof(*uoss
)))
2980 error
= __put_user(oss
.ss_sp
, &uoss
->ss_sp
) |
2981 __put_user(oss
.ss_size
, &uoss
->ss_size
) |
2982 __put_user(oss
.ss_flags
, &uoss
->ss_flags
);
2989 #ifdef __ARCH_WANT_SYS_SIGPENDING
2992 * sys_sigpending - examine pending signals
2993 * @set: where mask of pending signal is returned
2995 SYSCALL_DEFINE1(sigpending
, old_sigset_t __user
*, set
)
2997 return do_sigpending(set
, sizeof(*set
));
3002 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3004 * sys_sigprocmask - examine and change blocked signals
3005 * @how: whether to add, remove, or set signals
3006 * @nset: signals to add or remove (if non-null)
3007 * @oset: previous value of signal mask if non-null
3009 * Some platforms have their own version with special arguments;
3010 * others support only sys_rt_sigprocmask.
3013 SYSCALL_DEFINE3(sigprocmask
, int, how
, old_sigset_t __user
*, nset
,
3014 old_sigset_t __user
*, oset
)
3016 old_sigset_t old_set
, new_set
;
3017 sigset_t new_blocked
;
3019 old_set
= current
->blocked
.sig
[0];
3022 if (copy_from_user(&new_set
, nset
, sizeof(*nset
)))
3024 new_set
&= ~(sigmask(SIGKILL
) | sigmask(SIGSTOP
));
3026 new_blocked
= current
->blocked
;
3030 sigaddsetmask(&new_blocked
, new_set
);
3033 sigdelsetmask(&new_blocked
, new_set
);
3036 new_blocked
.sig
[0] = new_set
;
3042 set_current_blocked(&new_blocked
);
3046 if (copy_to_user(oset
, &old_set
, sizeof(*oset
)))
3052 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3054 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
3056 * sys_rt_sigaction - alter an action taken by a process
3057 * @sig: signal to be sent
3058 * @act: new sigaction
3059 * @oact: used to save the previous sigaction
3060 * @sigsetsize: size of sigset_t type
3062 SYSCALL_DEFINE4(rt_sigaction
, int, sig
,
3063 const struct sigaction __user
*, act
,
3064 struct sigaction __user
*, oact
,
3067 struct k_sigaction new_sa
, old_sa
;
3070 /* XXX: Don't preclude handling different sized sigset_t's. */
3071 if (sigsetsize
!= sizeof(sigset_t
))
3075 if (copy_from_user(&new_sa
.sa
, act
, sizeof(new_sa
.sa
)))
3079 ret
= do_sigaction(sig
, act
? &new_sa
: NULL
, oact
? &old_sa
: NULL
);
3082 if (copy_to_user(oact
, &old_sa
.sa
, sizeof(old_sa
.sa
)))
3088 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3090 #ifdef __ARCH_WANT_SYS_SGETMASK
3093 * For backwards compatibility. Functionality superseded by sigprocmask.
3095 SYSCALL_DEFINE0(sgetmask
)
3098 return current
->blocked
.sig
[0];
3101 SYSCALL_DEFINE1(ssetmask
, int, newmask
)
3103 int old
= current
->blocked
.sig
[0];
3106 siginitset(&newset
, newmask
& ~(sigmask(SIGKILL
) | sigmask(SIGSTOP
)));
3107 set_current_blocked(&newset
);
3111 #endif /* __ARCH_WANT_SGETMASK */
3113 #ifdef __ARCH_WANT_SYS_SIGNAL
3115 * For backwards compatibility. Functionality superseded by sigaction.
3117 SYSCALL_DEFINE2(signal
, int, sig
, __sighandler_t
, handler
)
3119 struct k_sigaction new_sa
, old_sa
;
3122 new_sa
.sa
.sa_handler
= handler
;
3123 new_sa
.sa
.sa_flags
= SA_ONESHOT
| SA_NOMASK
;
3124 sigemptyset(&new_sa
.sa
.sa_mask
);
3126 ret
= do_sigaction(sig
, &new_sa
, &old_sa
);
3128 return ret
? ret
: (unsigned long)old_sa
.sa
.sa_handler
;
3130 #endif /* __ARCH_WANT_SYS_SIGNAL */
3132 #ifdef __ARCH_WANT_SYS_PAUSE
3134 SYSCALL_DEFINE0(pause
)
3136 while (!signal_pending(current
)) {
3137 current
->state
= TASK_INTERRUPTIBLE
;
3140 return -ERESTARTNOHAND
;
3145 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3147 * sys_rt_sigsuspend - replace the signal mask for a value with the
3148 * @unewset value until a signal is received
3149 * @unewset: new signal mask value
3150 * @sigsetsize: size of sigset_t type
3152 SYSCALL_DEFINE2(rt_sigsuspend
, sigset_t __user
*, unewset
, size_t, sigsetsize
)
3156 /* XXX: Don't preclude handling different sized sigset_t's. */
3157 if (sigsetsize
!= sizeof(sigset_t
))
3160 if (copy_from_user(&newset
, unewset
, sizeof(newset
)))
3162 sigdelsetmask(&newset
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
3164 current
->saved_sigmask
= current
->blocked
;
3165 set_current_blocked(&newset
);
3167 current
->state
= TASK_INTERRUPTIBLE
;
3169 set_restore_sigmask();
3170 return -ERESTARTNOHAND
;
3172 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3174 __attribute__((weak
)) const char *arch_vma_name(struct vm_area_struct
*vma
)
3179 void __init
signals_init(void)
3181 sigqueue_cachep
= KMEM_CACHE(sigqueue
, SLAB_PANIC
);
3184 #ifdef CONFIG_KGDB_KDB
3185 #include <linux/kdb.h>
3187 * kdb_send_sig_info - Allows kdb to send signals without exposing
3188 * signal internals. This function checks if the required locks are
3189 * available before calling the main signal code, to avoid kdb
3193 kdb_send_sig_info(struct task_struct
*t
, struct siginfo
*info
)
3195 static struct task_struct
*kdb_prev_t
;
3197 if (!spin_trylock(&t
->sighand
->siglock
)) {
3198 kdb_printf("Can't do kill command now.\n"
3199 "The sigmask lock is held somewhere else in "
3200 "kernel, try again later\n");
3203 spin_unlock(&t
->sighand
->siglock
);
3204 new_t
= kdb_prev_t
!= t
;
3206 if (t
->state
!= TASK_RUNNING
&& new_t
) {
3207 kdb_printf("Process is not RUNNING, sending a signal from "
3208 "kdb risks deadlock\n"
3209 "on the run queue locks. "
3210 "The signal has _not_ been sent.\n"
3211 "Reissue the kill command if you want to risk "
3215 sig
= info
->si_signo
;
3216 if (send_sig_info(sig
, info
, t
))
3217 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3220 kdb_printf("Signal %d is sent to process %d.\n", sig
, t
->pid
);
3222 #endif /* CONFIG_KGDB_KDB */