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/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache
*sigqueue_cachep
;
42 static int __sig_ignored(struct task_struct
*t
, int sig
)
46 /* Is it explicitly or implicitly ignored? */
48 handler
= t
->sighand
->action
[sig
- 1].sa
.sa_handler
;
49 return handler
== SIG_IGN
||
50 (handler
== SIG_DFL
&& sig_kernel_ignore(sig
));
53 static int sig_ignored(struct task_struct
*t
, int sig
)
56 * Tracers always want to know about signals..
58 if (t
->ptrace
& PT_PTRACED
)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t
->blocked
, sig
) || sigismember(&t
->real_blocked
, sig
))
69 return __sig_ignored(t
, sig
);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t
*signal
, sigset_t
*blocked
)
81 switch (_NSIG_WORDS
) {
83 for (i
= _NSIG_WORDS
, ready
= 0; --i
>= 0 ;)
84 ready
|= signal
->sig
[i
] &~ blocked
->sig
[i
];
87 case 4: ready
= signal
->sig
[3] &~ blocked
->sig
[3];
88 ready
|= signal
->sig
[2] &~ blocked
->sig
[2];
89 ready
|= signal
->sig
[1] &~ blocked
->sig
[1];
90 ready
|= signal
->sig
[0] &~ blocked
->sig
[0];
93 case 2: ready
= signal
->sig
[1] &~ blocked
->sig
[1];
94 ready
|= signal
->sig
[0] &~ blocked
->sig
[0];
97 case 1: ready
= signal
->sig
[0] &~ blocked
->sig
[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct
*t
)
106 if (t
->signal
->group_stop_count
> 0 ||
107 PENDING(&t
->pending
, &t
->blocked
) ||
108 PENDING(&t
->signal
->shared_pending
, &t
->blocked
)) {
109 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct
*t
)
126 if (recalc_sigpending_tsk(t
))
127 signal_wake_up(t
, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current
) && !freezing(current
))
133 clear_thread_flag(TIF_SIGPENDING
);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending
*pending
, sigset_t
*mask
)
141 unsigned long i
, *s
, *m
, x
;
144 s
= pending
->signal
.sig
;
146 switch (_NSIG_WORDS
) {
148 for (i
= 0; i
< _NSIG_WORDS
; ++i
, ++s
, ++m
)
149 if ((x
= *s
&~ *m
) != 0) {
150 sig
= ffz(~x
) + i
*_NSIG_BPW
+ 1;
155 case 2: if ((x
= s
[0] &~ m
[0]) != 0)
157 else if ((x
= s
[1] &~ m
[1]) != 0)
164 case 1: if ((x
= *s
&~ *m
) != 0)
172 static struct sigqueue
*__sigqueue_alloc(struct task_struct
*t
, gfp_t flags
,
175 struct sigqueue
*q
= NULL
;
176 struct user_struct
*user
;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user
->sigpending
);
185 if (override_rlimit
||
186 atomic_read(&user
->sigpending
) <=
187 t
->signal
->rlim
[RLIMIT_SIGPENDING
].rlim_cur
)
188 q
= kmem_cache_alloc(sigqueue_cachep
, flags
);
189 if (unlikely(q
== NULL
)) {
190 atomic_dec(&user
->sigpending
);
192 INIT_LIST_HEAD(&q
->list
);
194 q
->user
= get_uid(user
);
199 static void __sigqueue_free(struct sigqueue
*q
)
201 if (q
->flags
& SIGQUEUE_PREALLOC
)
203 atomic_dec(&q
->user
->sigpending
);
205 kmem_cache_free(sigqueue_cachep
, q
);
208 void flush_sigqueue(struct sigpending
*queue
)
212 sigemptyset(&queue
->signal
);
213 while (!list_empty(&queue
->list
)) {
214 q
= list_entry(queue
->list
.next
, struct sigqueue
, list
);
215 list_del_init(&q
->list
);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct
*t
)
227 spin_lock_irqsave(&t
->sighand
->siglock
, flags
);
228 clear_tsk_thread_flag(t
, TIF_SIGPENDING
);
229 flush_sigqueue(&t
->pending
);
230 flush_sigqueue(&t
->signal
->shared_pending
);
231 spin_unlock_irqrestore(&t
->sighand
->siglock
, flags
);
234 void ignore_signals(struct task_struct
*t
)
238 for (i
= 0; i
< _NSIG
; ++i
)
239 t
->sighand
->action
[i
].sa
.sa_handler
= SIG_IGN
;
245 * Flush all handlers for a task.
249 flush_signal_handlers(struct task_struct
*t
, int force_default
)
252 struct k_sigaction
*ka
= &t
->sighand
->action
[0];
253 for (i
= _NSIG
; i
!= 0 ; i
--) {
254 if (force_default
|| ka
->sa
.sa_handler
!= SIG_IGN
)
255 ka
->sa
.sa_handler
= SIG_DFL
;
257 sigemptyset(&ka
->sa
.sa_mask
);
262 int unhandled_signal(struct task_struct
*tsk
, int sig
)
264 if (is_global_init(tsk
))
266 if (tsk
->ptrace
& PT_PTRACED
)
268 return (tsk
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
) ||
269 (tsk
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_DFL
);
273 /* Notify the system that a driver wants to block all signals for this
274 * process, and wants to be notified if any signals at all were to be
275 * sent/acted upon. If the notifier routine returns non-zero, then the
276 * signal will be acted upon after all. If the notifier routine returns 0,
277 * then then signal will be blocked. Only one block per process is
278 * allowed. priv is a pointer to private data that the notifier routine
279 * can use to determine if the signal should be blocked or not. */
282 block_all_signals(int (*notifier
)(void *priv
), void *priv
, sigset_t
*mask
)
286 spin_lock_irqsave(¤t
->sighand
->siglock
, flags
);
287 current
->notifier_mask
= mask
;
288 current
->notifier_data
= priv
;
289 current
->notifier
= notifier
;
290 spin_unlock_irqrestore(¤t
->sighand
->siglock
, flags
);
293 /* Notify the system that blocking has ended. */
296 unblock_all_signals(void)
300 spin_lock_irqsave(¤t
->sighand
->siglock
, flags
);
301 current
->notifier
= NULL
;
302 current
->notifier_data
= NULL
;
304 spin_unlock_irqrestore(¤t
->sighand
->siglock
, flags
);
307 static int collect_signal(int sig
, struct sigpending
*list
, siginfo_t
*info
)
309 struct sigqueue
*q
, *first
= NULL
;
310 int still_pending
= 0;
312 if (unlikely(!sigismember(&list
->signal
, sig
)))
316 * Collect the siginfo appropriate to this signal. Check if
317 * there is another siginfo for the same signal.
319 list_for_each_entry(q
, &list
->list
, list
) {
320 if (q
->info
.si_signo
== sig
) {
329 list_del_init(&first
->list
);
330 copy_siginfo(info
, &first
->info
);
331 __sigqueue_free(first
);
333 sigdelset(&list
->signal
, sig
);
336 /* Ok, it wasn't in the queue. This must be
337 a fast-pathed signal or we must have been
338 out of queue space. So zero out the info.
340 sigdelset(&list
->signal
, sig
);
341 info
->si_signo
= sig
;
350 static int __dequeue_signal(struct sigpending
*pending
, sigset_t
*mask
,
353 int sig
= next_signal(pending
, mask
);
356 if (current
->notifier
) {
357 if (sigismember(current
->notifier_mask
, sig
)) {
358 if (!(current
->notifier
)(current
->notifier_data
)) {
359 clear_thread_flag(TIF_SIGPENDING
);
365 if (!collect_signal(sig
, pending
, info
))
373 * Dequeue a signal and return the element to the caller, which is
374 * expected to free it.
376 * All callers have to hold the siglock.
378 int dequeue_signal(struct task_struct
*tsk
, sigset_t
*mask
, siginfo_t
*info
)
382 /* We only dequeue private signals from ourselves, we don't let
383 * signalfd steal them
385 signr
= __dequeue_signal(&tsk
->pending
, mask
, info
);
387 signr
= __dequeue_signal(&tsk
->signal
->shared_pending
,
392 * itimers are process shared and we restart periodic
393 * itimers in the signal delivery path to prevent DoS
394 * attacks in the high resolution timer case. This is
395 * compliant with the old way of self restarting
396 * itimers, as the SIGALRM is a legacy signal and only
397 * queued once. Changing the restart behaviour to
398 * restart the timer in the signal dequeue path is
399 * reducing the timer noise on heavy loaded !highres
402 if (unlikely(signr
== SIGALRM
)) {
403 struct hrtimer
*tmr
= &tsk
->signal
->real_timer
;
405 if (!hrtimer_is_queued(tmr
) &&
406 tsk
->signal
->it_real_incr
.tv64
!= 0) {
407 hrtimer_forward(tmr
, tmr
->base
->get_time(),
408 tsk
->signal
->it_real_incr
);
409 hrtimer_restart(tmr
);
418 if (unlikely(sig_kernel_stop(signr
))) {
420 * Set a marker that we have dequeued a stop signal. Our
421 * caller might release the siglock and then the pending
422 * stop signal it is about to process is no longer in the
423 * pending bitmasks, but must still be cleared by a SIGCONT
424 * (and overruled by a SIGKILL). So those cases clear this
425 * shared flag after we've set it. Note that this flag may
426 * remain set after the signal we return is ignored or
427 * handled. That doesn't matter because its only purpose
428 * is to alert stop-signal processing code when another
429 * processor has come along and cleared the flag.
431 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_EXIT
))
432 tsk
->signal
->flags
|= SIGNAL_STOP_DEQUEUED
;
434 if ((info
->si_code
& __SI_MASK
) == __SI_TIMER
&& info
->si_sys_private
) {
436 * Release the siglock to ensure proper locking order
437 * of timer locks outside of siglocks. Note, we leave
438 * irqs disabled here, since the posix-timers code is
439 * about to disable them again anyway.
441 spin_unlock(&tsk
->sighand
->siglock
);
442 do_schedule_next_timer(info
);
443 spin_lock(&tsk
->sighand
->siglock
);
449 * Tell a process that it has a new active signal..
451 * NOTE! we rely on the previous spin_lock to
452 * lock interrupts for us! We can only be called with
453 * "siglock" held, and the local interrupt must
454 * have been disabled when that got acquired!
456 * No need to set need_resched since signal event passing
457 * goes through ->blocked
459 void signal_wake_up(struct task_struct
*t
, int resume
)
463 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
466 * For SIGKILL, we want to wake it up in the stopped/traced/killable
467 * case. We don't check t->state here because there is a race with it
468 * executing another processor and just now entering stopped state.
469 * By using wake_up_state, we ensure the process will wake up and
470 * handle its death signal.
472 mask
= TASK_INTERRUPTIBLE
;
474 mask
|= TASK_WAKEKILL
;
475 if (!wake_up_state(t
, mask
))
480 * Remove signals in mask from the pending set and queue.
481 * Returns 1 if any signals were found.
483 * All callers must be holding the siglock.
485 * This version takes a sigset mask and looks at all signals,
486 * not just those in the first mask word.
488 static int rm_from_queue_full(sigset_t
*mask
, struct sigpending
*s
)
490 struct sigqueue
*q
, *n
;
493 sigandsets(&m
, mask
, &s
->signal
);
494 if (sigisemptyset(&m
))
497 signandsets(&s
->signal
, &s
->signal
, mask
);
498 list_for_each_entry_safe(q
, n
, &s
->list
, list
) {
499 if (sigismember(mask
, q
->info
.si_signo
)) {
500 list_del_init(&q
->list
);
507 * Remove signals in mask from the pending set and queue.
508 * Returns 1 if any signals were found.
510 * All callers must be holding the siglock.
512 static int rm_from_queue(unsigned long mask
, struct sigpending
*s
)
514 struct sigqueue
*q
, *n
;
516 if (!sigtestsetmask(&s
->signal
, mask
))
519 sigdelsetmask(&s
->signal
, mask
);
520 list_for_each_entry_safe(q
, n
, &s
->list
, list
) {
521 if (q
->info
.si_signo
< SIGRTMIN
&&
522 (mask
& sigmask(q
->info
.si_signo
))) {
523 list_del_init(&q
->list
);
531 * Bad permissions for sending the signal
533 static int check_kill_permission(int sig
, struct siginfo
*info
,
534 struct task_struct
*t
)
539 if (!valid_signal(sig
))
542 if (info
!= SEND_SIG_NOINFO
&& (is_si_special(info
) || SI_FROMKERNEL(info
)))
545 error
= audit_signal_info(sig
, t
); /* Let audit system see the signal */
549 if ((current
->euid
^ t
->suid
) && (current
->euid
^ t
->uid
) &&
550 (current
->uid
^ t
->suid
) && (current
->uid
^ t
->uid
) &&
551 !capable(CAP_KILL
)) {
554 read_lock(&tasklist_lock
);
555 sid
= task_session(t
);
556 read_unlock(&tasklist_lock
);
558 * We don't return the error if sid == NULL. The
559 * task was unhashed, the caller must notice this.
561 if (!sid
|| sid
== task_session(current
))
568 return security_task_kill(t
, info
, sig
, 0);
572 static void do_notify_parent_cldstop(struct task_struct
*tsk
, int why
);
575 * Handle magic process-wide effects of stop/continue signals. Unlike
576 * the signal actions, these happen immediately at signal-generation
577 * time regardless of blocking, ignoring, or handling. This does the
578 * actual continuing for SIGCONT, but not the actual stopping for stop
579 * signals. The process stop is done as a signal action for SIG_DFL.
581 * Returns true if the signal should be actually delivered, otherwise
582 * it should be dropped.
584 static int prepare_signal(int sig
, struct task_struct
*p
)
586 struct signal_struct
*signal
= p
->signal
;
587 struct task_struct
*t
;
589 if (unlikely(signal
->flags
& SIGNAL_GROUP_EXIT
)) {
591 * The process is in the middle of dying, nothing to do.
593 } else if (sig_kernel_stop(sig
)) {
595 * This is a stop signal. Remove SIGCONT from all queues.
597 rm_from_queue(sigmask(SIGCONT
), &signal
->shared_pending
);
600 rm_from_queue(sigmask(SIGCONT
), &t
->pending
);
601 } while_each_thread(p
, t
);
602 } else if (sig
== SIGCONT
) {
605 * Remove all stop signals from all queues,
606 * and wake all threads.
608 rm_from_queue(SIG_KERNEL_STOP_MASK
, &signal
->shared_pending
);
612 rm_from_queue(SIG_KERNEL_STOP_MASK
, &t
->pending
);
614 * If there is a handler for SIGCONT, we must make
615 * sure that no thread returns to user mode before
616 * we post the signal, in case it was the only
617 * thread eligible to run the signal handler--then
618 * it must not do anything between resuming and
619 * running the handler. With the TIF_SIGPENDING
620 * flag set, the thread will pause and acquire the
621 * siglock that we hold now and until we've queued
622 * the pending signal.
624 * Wake up the stopped thread _after_ setting
627 state
= __TASK_STOPPED
;
628 if (sig_user_defined(t
, SIGCONT
) && !sigismember(&t
->blocked
, SIGCONT
)) {
629 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
630 state
|= TASK_INTERRUPTIBLE
;
632 wake_up_state(t
, state
);
633 } while_each_thread(p
, t
);
636 * Notify the parent with CLD_CONTINUED if we were stopped.
638 * If we were in the middle of a group stop, we pretend it
639 * was already finished, and then continued. Since SIGCHLD
640 * doesn't queue we report only CLD_STOPPED, as if the next
641 * CLD_CONTINUED was dropped.
644 if (signal
->flags
& SIGNAL_STOP_STOPPED
)
645 why
|= SIGNAL_CLD_CONTINUED
;
646 else if (signal
->group_stop_count
)
647 why
|= SIGNAL_CLD_STOPPED
;
651 * The first thread which returns from finish_stop()
652 * will take ->siglock, notice SIGNAL_CLD_MASK, and
653 * notify its parent. See get_signal_to_deliver().
655 signal
->flags
= why
| SIGNAL_STOP_CONTINUED
;
656 signal
->group_stop_count
= 0;
657 signal
->group_exit_code
= 0;
660 * We are not stopped, but there could be a stop
661 * signal in the middle of being processed after
662 * being removed from the queue. Clear that too.
664 signal
->flags
&= ~SIGNAL_STOP_DEQUEUED
;
668 return !sig_ignored(p
, sig
);
672 * Test if P wants to take SIG. After we've checked all threads with this,
673 * it's equivalent to finding no threads not blocking SIG. Any threads not
674 * blocking SIG were ruled out because they are not running and already
675 * have pending signals. Such threads will dequeue from the shared queue
676 * as soon as they're available, so putting the signal on the shared queue
677 * will be equivalent to sending it to one such thread.
679 static inline int wants_signal(int sig
, struct task_struct
*p
)
681 if (sigismember(&p
->blocked
, sig
))
683 if (p
->flags
& PF_EXITING
)
687 if (task_is_stopped_or_traced(p
))
689 return task_curr(p
) || !signal_pending(p
);
692 static void complete_signal(int sig
, struct task_struct
*p
, int group
)
694 struct signal_struct
*signal
= p
->signal
;
695 struct task_struct
*t
;
698 * Now find a thread we can wake up to take the signal off the queue.
700 * If the main thread wants the signal, it gets first crack.
701 * Probably the least surprising to the average bear.
703 if (wants_signal(sig
, p
))
705 else if (!group
|| thread_group_empty(p
))
707 * There is just one thread and it does not need to be woken.
708 * It will dequeue unblocked signals before it runs again.
713 * Otherwise try to find a suitable thread.
715 t
= signal
->curr_target
;
716 while (!wants_signal(sig
, t
)) {
718 if (t
== signal
->curr_target
)
720 * No thread needs to be woken.
721 * Any eligible threads will see
722 * the signal in the queue soon.
726 signal
->curr_target
= t
;
730 * Found a killable thread. If the signal will be fatal,
731 * then start taking the whole group down immediately.
733 if (sig_fatal(p
, sig
) && !(signal
->flags
& SIGNAL_GROUP_EXIT
) &&
734 !sigismember(&t
->real_blocked
, sig
) &&
735 (sig
== SIGKILL
|| !(t
->ptrace
& PT_PTRACED
))) {
737 * This signal will be fatal to the whole group.
739 if (!sig_kernel_coredump(sig
)) {
741 * Start a group exit and wake everybody up.
742 * This way we don't have other threads
743 * running and doing things after a slower
744 * thread has the fatal signal pending.
746 signal
->flags
= SIGNAL_GROUP_EXIT
;
747 signal
->group_exit_code
= sig
;
748 signal
->group_stop_count
= 0;
751 sigaddset(&t
->pending
.signal
, SIGKILL
);
752 signal_wake_up(t
, 1);
753 } while_each_thread(p
, t
);
759 * The signal is already in the shared-pending queue.
760 * Tell the chosen thread to wake up and dequeue it.
762 signal_wake_up(t
, sig
== SIGKILL
);
766 static inline int legacy_queue(struct sigpending
*signals
, int sig
)
768 return (sig
< SIGRTMIN
) && sigismember(&signals
->signal
, sig
);
771 static int send_signal(int sig
, struct siginfo
*info
, struct task_struct
*t
,
774 struct sigpending
*pending
;
777 assert_spin_locked(&t
->sighand
->siglock
);
778 if (!prepare_signal(sig
, t
))
781 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
783 * Short-circuit ignored signals and support queuing
784 * exactly one non-rt signal, so that we can get more
785 * detailed information about the cause of the signal.
787 if (legacy_queue(pending
, sig
))
790 * fast-pathed signals for kernel-internal things like SIGSTOP
793 if (info
== SEND_SIG_FORCED
)
796 /* Real-time signals must be queued if sent by sigqueue, or
797 some other real-time mechanism. It is implementation
798 defined whether kill() does so. We attempt to do so, on
799 the principle of least surprise, but since kill is not
800 allowed to fail with EAGAIN when low on memory we just
801 make sure at least one signal gets delivered and don't
802 pass on the info struct. */
804 q
= __sigqueue_alloc(t
, GFP_ATOMIC
, (sig
< SIGRTMIN
&&
805 (is_si_special(info
) ||
806 info
->si_code
>= 0)));
808 list_add_tail(&q
->list
, &pending
->list
);
809 switch ((unsigned long) info
) {
810 case (unsigned long) SEND_SIG_NOINFO
:
811 q
->info
.si_signo
= sig
;
812 q
->info
.si_errno
= 0;
813 q
->info
.si_code
= SI_USER
;
814 q
->info
.si_pid
= task_pid_vnr(current
);
815 q
->info
.si_uid
= current
->uid
;
817 case (unsigned long) SEND_SIG_PRIV
:
818 q
->info
.si_signo
= sig
;
819 q
->info
.si_errno
= 0;
820 q
->info
.si_code
= SI_KERNEL
;
825 copy_siginfo(&q
->info
, info
);
828 } else if (!is_si_special(info
)) {
829 if (sig
>= SIGRTMIN
&& info
->si_code
!= SI_USER
)
831 * Queue overflow, abort. We may abort if the signal was rt
832 * and sent by user using something other than kill().
838 signalfd_notify(t
, sig
);
839 sigaddset(&pending
->signal
, sig
);
840 complete_signal(sig
, t
, group
);
844 int print_fatal_signals
;
846 static void print_fatal_signal(struct pt_regs
*regs
, int signr
)
848 printk("%s/%d: potentially unexpected fatal signal %d.\n",
849 current
->comm
, task_pid_nr(current
), signr
);
851 #if defined(__i386__) && !defined(__arch_um__)
852 printk("code at %08lx: ", regs
->ip
);
855 for (i
= 0; i
< 16; i
++) {
858 __get_user(insn
, (unsigned char *)(regs
->ip
+ i
));
859 printk("%02x ", insn
);
867 static int __init
setup_print_fatal_signals(char *str
)
869 get_option (&str
, &print_fatal_signals
);
874 __setup("print-fatal-signals=", setup_print_fatal_signals
);
877 __group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
879 return send_signal(sig
, info
, p
, 1);
883 specific_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
885 return send_signal(sig
, info
, t
, 0);
889 * Force a signal that the process can't ignore: if necessary
890 * we unblock the signal and change any SIG_IGN to SIG_DFL.
892 * Note: If we unblock the signal, we always reset it to SIG_DFL,
893 * since we do not want to have a signal handler that was blocked
894 * be invoked when user space had explicitly blocked it.
896 * We don't want to have recursive SIGSEGV's etc, for example.
899 force_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
901 unsigned long int flags
;
902 int ret
, blocked
, ignored
;
903 struct k_sigaction
*action
;
905 spin_lock_irqsave(&t
->sighand
->siglock
, flags
);
906 action
= &t
->sighand
->action
[sig
-1];
907 ignored
= action
->sa
.sa_handler
== SIG_IGN
;
908 blocked
= sigismember(&t
->blocked
, sig
);
909 if (blocked
|| ignored
) {
910 action
->sa
.sa_handler
= SIG_DFL
;
912 sigdelset(&t
->blocked
, sig
);
913 recalc_sigpending_and_wake(t
);
916 ret
= specific_send_sig_info(sig
, info
, t
);
917 spin_unlock_irqrestore(&t
->sighand
->siglock
, flags
);
923 force_sig_specific(int sig
, struct task_struct
*t
)
925 force_sig_info(sig
, SEND_SIG_FORCED
, t
);
929 * Nuke all other threads in the group.
931 void zap_other_threads(struct task_struct
*p
)
933 struct task_struct
*t
;
935 p
->signal
->group_stop_count
= 0;
937 for (t
= next_thread(p
); t
!= p
; t
= next_thread(t
)) {
939 * Don't bother with already dead threads
944 /* SIGKILL will be handled before any pending SIGSTOP */
945 sigaddset(&t
->pending
.signal
, SIGKILL
);
946 signal_wake_up(t
, 1);
950 int __fatal_signal_pending(struct task_struct
*tsk
)
952 return sigismember(&tsk
->pending
.signal
, SIGKILL
);
954 EXPORT_SYMBOL(__fatal_signal_pending
);
956 struct sighand_struct
*lock_task_sighand(struct task_struct
*tsk
, unsigned long *flags
)
958 struct sighand_struct
*sighand
;
962 sighand
= rcu_dereference(tsk
->sighand
);
963 if (unlikely(sighand
== NULL
))
966 spin_lock_irqsave(&sighand
->siglock
, *flags
);
967 if (likely(sighand
== tsk
->sighand
))
969 spin_unlock_irqrestore(&sighand
->siglock
, *flags
);
976 int group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
981 ret
= check_kill_permission(sig
, info
, p
);
985 if (lock_task_sighand(p
, &flags
)) {
986 ret
= __group_send_sig_info(sig
, info
, p
);
987 unlock_task_sighand(p
, &flags
);
995 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
996 * control characters do (^C, ^Z etc)
999 int __kill_pgrp_info(int sig
, struct siginfo
*info
, struct pid
*pgrp
)
1001 struct task_struct
*p
= NULL
;
1002 int retval
, success
;
1006 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
1007 int err
= group_send_sig_info(sig
, info
, p
);
1010 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
1011 return success
? 0 : retval
;
1014 int kill_pid_info(int sig
, struct siginfo
*info
, struct pid
*pid
)
1017 struct task_struct
*p
;
1021 p
= pid_task(pid
, PIDTYPE_PID
);
1023 error
= group_send_sig_info(sig
, info
, p
);
1024 if (unlikely(error
== -ESRCH
))
1026 * The task was unhashed in between, try again.
1027 * If it is dead, pid_task() will return NULL,
1028 * if we race with de_thread() it will find the
1039 kill_proc_info(int sig
, struct siginfo
*info
, pid_t pid
)
1043 error
= kill_pid_info(sig
, info
, find_vpid(pid
));
1048 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1049 int kill_pid_info_as_uid(int sig
, struct siginfo
*info
, struct pid
*pid
,
1050 uid_t uid
, uid_t euid
, u32 secid
)
1053 struct task_struct
*p
;
1055 if (!valid_signal(sig
))
1058 read_lock(&tasklist_lock
);
1059 p
= pid_task(pid
, PIDTYPE_PID
);
1064 if ((info
== SEND_SIG_NOINFO
|| (!is_si_special(info
) && SI_FROMUSER(info
)))
1065 && (euid
!= p
->suid
) && (euid
!= p
->uid
)
1066 && (uid
!= p
->suid
) && (uid
!= p
->uid
)) {
1070 ret
= security_task_kill(p
, info
, sig
, secid
);
1073 if (sig
&& p
->sighand
) {
1074 unsigned long flags
;
1075 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1076 ret
= __group_send_sig_info(sig
, info
, p
);
1077 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1080 read_unlock(&tasklist_lock
);
1083 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid
);
1086 * kill_something_info() interprets pid in interesting ways just like kill(2).
1088 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1089 * is probably wrong. Should make it like BSD or SYSV.
1092 static int kill_something_info(int sig
, struct siginfo
*info
, int pid
)
1098 ret
= kill_pid_info(sig
, info
, find_vpid(pid
));
1103 read_lock(&tasklist_lock
);
1105 ret
= __kill_pgrp_info(sig
, info
,
1106 pid
? find_vpid(-pid
) : task_pgrp(current
));
1108 int retval
= 0, count
= 0;
1109 struct task_struct
* p
;
1111 for_each_process(p
) {
1112 if (p
->pid
> 1 && !same_thread_group(p
, current
)) {
1113 int err
= group_send_sig_info(sig
, info
, p
);
1119 ret
= count
? retval
: -ESRCH
;
1121 read_unlock(&tasklist_lock
);
1127 * These are for backward compatibility with the rest of the kernel source.
1131 * The caller must ensure the task can't exit.
1134 send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1137 unsigned long flags
;
1140 * Make sure legacy kernel users don't send in bad values
1141 * (normal paths check this in check_kill_permission).
1143 if (!valid_signal(sig
))
1146 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1147 ret
= specific_send_sig_info(sig
, info
, p
);
1148 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1152 #define __si_special(priv) \
1153 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1156 send_sig(int sig
, struct task_struct
*p
, int priv
)
1158 return send_sig_info(sig
, __si_special(priv
), p
);
1162 force_sig(int sig
, struct task_struct
*p
)
1164 force_sig_info(sig
, SEND_SIG_PRIV
, p
);
1168 * When things go south during signal handling, we
1169 * will force a SIGSEGV. And if the signal that caused
1170 * the problem was already a SIGSEGV, we'll want to
1171 * make sure we don't even try to deliver the signal..
1174 force_sigsegv(int sig
, struct task_struct
*p
)
1176 if (sig
== SIGSEGV
) {
1177 unsigned long flags
;
1178 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1179 p
->sighand
->action
[sig
- 1].sa
.sa_handler
= SIG_DFL
;
1180 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1182 force_sig(SIGSEGV
, p
);
1186 int kill_pgrp(struct pid
*pid
, int sig
, int priv
)
1190 read_lock(&tasklist_lock
);
1191 ret
= __kill_pgrp_info(sig
, __si_special(priv
), pid
);
1192 read_unlock(&tasklist_lock
);
1196 EXPORT_SYMBOL(kill_pgrp
);
1198 int kill_pid(struct pid
*pid
, int sig
, int priv
)
1200 return kill_pid_info(sig
, __si_special(priv
), pid
);
1202 EXPORT_SYMBOL(kill_pid
);
1205 kill_proc(pid_t pid
, int sig
, int priv
)
1210 ret
= kill_pid_info(sig
, __si_special(priv
), find_pid(pid
));
1216 * These functions support sending signals using preallocated sigqueue
1217 * structures. This is needed "because realtime applications cannot
1218 * afford to lose notifications of asynchronous events, like timer
1219 * expirations or I/O completions". In the case of Posix Timers
1220 * we allocate the sigqueue structure from the timer_create. If this
1221 * allocation fails we are able to report the failure to the application
1222 * with an EAGAIN error.
1225 struct sigqueue
*sigqueue_alloc(void)
1229 if ((q
= __sigqueue_alloc(current
, GFP_KERNEL
, 0)))
1230 q
->flags
|= SIGQUEUE_PREALLOC
;
1234 void sigqueue_free(struct sigqueue
*q
)
1236 unsigned long flags
;
1237 spinlock_t
*lock
= ¤t
->sighand
->siglock
;
1239 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1241 * If the signal is still pending remove it from the
1242 * pending queue. We must hold ->siglock while testing
1243 * q->list to serialize with collect_signal().
1245 spin_lock_irqsave(lock
, flags
);
1246 if (!list_empty(&q
->list
))
1247 list_del_init(&q
->list
);
1248 spin_unlock_irqrestore(lock
, flags
);
1250 q
->flags
&= ~SIGQUEUE_PREALLOC
;
1254 int send_sigqueue(struct sigqueue
*q
, struct task_struct
*t
, int group
)
1256 int sig
= q
->info
.si_signo
;
1257 struct sigpending
*pending
;
1258 unsigned long flags
;
1261 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1264 if (!likely(lock_task_sighand(t
, &flags
)))
1267 ret
= 1; /* the signal is ignored */
1268 if (!prepare_signal(sig
, t
))
1272 if (unlikely(!list_empty(&q
->list
))) {
1274 * If an SI_TIMER entry is already queue just increment
1275 * the overrun count.
1277 BUG_ON(q
->info
.si_code
!= SI_TIMER
);
1278 q
->info
.si_overrun
++;
1282 signalfd_notify(t
, sig
);
1283 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
1284 list_add_tail(&q
->list
, &pending
->list
);
1285 sigaddset(&pending
->signal
, sig
);
1286 complete_signal(sig
, t
, group
);
1288 unlock_task_sighand(t
, &flags
);
1294 * Wake up any threads in the parent blocked in wait* syscalls.
1296 static inline void __wake_up_parent(struct task_struct
*p
,
1297 struct task_struct
*parent
)
1299 wake_up_interruptible_sync(&parent
->signal
->wait_chldexit
);
1303 * Let a parent know about the death of a child.
1304 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1307 void do_notify_parent(struct task_struct
*tsk
, int sig
)
1309 struct siginfo info
;
1310 unsigned long flags
;
1311 struct sighand_struct
*psig
;
1315 /* do_notify_parent_cldstop should have been called instead. */
1316 BUG_ON(task_is_stopped_or_traced(tsk
));
1318 BUG_ON(!tsk
->ptrace
&&
1319 (tsk
->group_leader
!= tsk
|| !thread_group_empty(tsk
)));
1321 info
.si_signo
= sig
;
1324 * we are under tasklist_lock here so our parent is tied to
1325 * us and cannot exit and release its namespace.
1327 * the only it can is to switch its nsproxy with sys_unshare,
1328 * bu uncharing pid namespaces is not allowed, so we'll always
1329 * see relevant namespace
1331 * write_lock() currently calls preempt_disable() which is the
1332 * same as rcu_read_lock(), but according to Oleg, this is not
1333 * correct to rely on this
1336 info
.si_pid
= task_pid_nr_ns(tsk
, tsk
->parent
->nsproxy
->pid_ns
);
1339 info
.si_uid
= tsk
->uid
;
1341 /* FIXME: find out whether or not this is supposed to be c*time. */
1342 info
.si_utime
= cputime_to_jiffies(cputime_add(tsk
->utime
,
1343 tsk
->signal
->utime
));
1344 info
.si_stime
= cputime_to_jiffies(cputime_add(tsk
->stime
,
1345 tsk
->signal
->stime
));
1347 info
.si_status
= tsk
->exit_code
& 0x7f;
1348 if (tsk
->exit_code
& 0x80)
1349 info
.si_code
= CLD_DUMPED
;
1350 else if (tsk
->exit_code
& 0x7f)
1351 info
.si_code
= CLD_KILLED
;
1353 info
.si_code
= CLD_EXITED
;
1354 info
.si_status
= tsk
->exit_code
>> 8;
1357 psig
= tsk
->parent
->sighand
;
1358 spin_lock_irqsave(&psig
->siglock
, flags
);
1359 if (!tsk
->ptrace
&& sig
== SIGCHLD
&&
1360 (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
||
1361 (psig
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDWAIT
))) {
1363 * We are exiting and our parent doesn't care. POSIX.1
1364 * defines special semantics for setting SIGCHLD to SIG_IGN
1365 * or setting the SA_NOCLDWAIT flag: we should be reaped
1366 * automatically and not left for our parent's wait4 call.
1367 * Rather than having the parent do it as a magic kind of
1368 * signal handler, we just set this to tell do_exit that we
1369 * can be cleaned up without becoming a zombie. Note that
1370 * we still call __wake_up_parent in this case, because a
1371 * blocked sys_wait4 might now return -ECHILD.
1373 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1374 * is implementation-defined: we do (if you don't want
1375 * it, just use SIG_IGN instead).
1377 tsk
->exit_signal
= -1;
1378 if (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
)
1381 if (valid_signal(sig
) && sig
> 0)
1382 __group_send_sig_info(sig
, &info
, tsk
->parent
);
1383 __wake_up_parent(tsk
, tsk
->parent
);
1384 spin_unlock_irqrestore(&psig
->siglock
, flags
);
1387 static void do_notify_parent_cldstop(struct task_struct
*tsk
, int why
)
1389 struct siginfo info
;
1390 unsigned long flags
;
1391 struct task_struct
*parent
;
1392 struct sighand_struct
*sighand
;
1394 if (tsk
->ptrace
& PT_PTRACED
)
1395 parent
= tsk
->parent
;
1397 tsk
= tsk
->group_leader
;
1398 parent
= tsk
->real_parent
;
1401 info
.si_signo
= SIGCHLD
;
1404 * see comment in do_notify_parent() abot the following 3 lines
1407 info
.si_pid
= task_pid_nr_ns(tsk
, tsk
->parent
->nsproxy
->pid_ns
);
1410 info
.si_uid
= tsk
->uid
;
1412 /* FIXME: find out whether or not this is supposed to be c*time. */
1413 info
.si_utime
= cputime_to_jiffies(tsk
->utime
);
1414 info
.si_stime
= cputime_to_jiffies(tsk
->stime
);
1419 info
.si_status
= SIGCONT
;
1422 info
.si_status
= tsk
->signal
->group_exit_code
& 0x7f;
1425 info
.si_status
= tsk
->exit_code
& 0x7f;
1431 sighand
= parent
->sighand
;
1432 spin_lock_irqsave(&sighand
->siglock
, flags
);
1433 if (sighand
->action
[SIGCHLD
-1].sa
.sa_handler
!= SIG_IGN
&&
1434 !(sighand
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDSTOP
))
1435 __group_send_sig_info(SIGCHLD
, &info
, parent
);
1437 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1439 __wake_up_parent(tsk
, parent
);
1440 spin_unlock_irqrestore(&sighand
->siglock
, flags
);
1443 static inline int may_ptrace_stop(void)
1445 if (!likely(current
->ptrace
& PT_PTRACED
))
1448 * Are we in the middle of do_coredump?
1449 * If so and our tracer is also part of the coredump stopping
1450 * is a deadlock situation, and pointless because our tracer
1451 * is dead so don't allow us to stop.
1452 * If SIGKILL was already sent before the caller unlocked
1453 * ->siglock we must see ->core_waiters != 0. Otherwise it
1454 * is safe to enter schedule().
1456 if (unlikely(current
->mm
->core_waiters
) &&
1457 unlikely(current
->mm
== current
->parent
->mm
))
1464 * Return nonzero if there is a SIGKILL that should be waking us up.
1465 * Called with the siglock held.
1467 static int sigkill_pending(struct task_struct
*tsk
)
1469 return ((sigismember(&tsk
->pending
.signal
, SIGKILL
) ||
1470 sigismember(&tsk
->signal
->shared_pending
.signal
, SIGKILL
)) &&
1471 !unlikely(sigismember(&tsk
->blocked
, SIGKILL
)));
1475 * This must be called with current->sighand->siglock held.
1477 * This should be the path for all ptrace stops.
1478 * We always set current->last_siginfo while stopped here.
1479 * That makes it a way to test a stopped process for
1480 * being ptrace-stopped vs being job-control-stopped.
1482 * If we actually decide not to stop at all because the tracer
1483 * is gone, we keep current->exit_code unless clear_code.
1485 static void ptrace_stop(int exit_code
, int clear_code
, siginfo_t
*info
)
1489 if (arch_ptrace_stop_needed(exit_code
, info
)) {
1491 * The arch code has something special to do before a
1492 * ptrace stop. This is allowed to block, e.g. for faults
1493 * on user stack pages. We can't keep the siglock while
1494 * calling arch_ptrace_stop, so we must release it now.
1495 * To preserve proper semantics, we must do this before
1496 * any signal bookkeeping like checking group_stop_count.
1497 * Meanwhile, a SIGKILL could come in before we retake the
1498 * siglock. That must prevent us from sleeping in TASK_TRACED.
1499 * So after regaining the lock, we must check for SIGKILL.
1501 spin_unlock_irq(¤t
->sighand
->siglock
);
1502 arch_ptrace_stop(exit_code
, info
);
1503 spin_lock_irq(¤t
->sighand
->siglock
);
1504 killed
= sigkill_pending(current
);
1508 * If there is a group stop in progress,
1509 * we must participate in the bookkeeping.
1511 if (current
->signal
->group_stop_count
> 0)
1512 --current
->signal
->group_stop_count
;
1514 current
->last_siginfo
= info
;
1515 current
->exit_code
= exit_code
;
1517 /* Let the debugger run. */
1518 __set_current_state(TASK_TRACED
);
1519 spin_unlock_irq(¤t
->sighand
->siglock
);
1520 read_lock(&tasklist_lock
);
1521 if (!unlikely(killed
) && may_ptrace_stop()) {
1522 do_notify_parent_cldstop(current
, CLD_TRAPPED
);
1523 read_unlock(&tasklist_lock
);
1527 * By the time we got the lock, our tracer went away.
1528 * Don't drop the lock yet, another tracer may come.
1530 __set_current_state(TASK_RUNNING
);
1532 current
->exit_code
= 0;
1533 read_unlock(&tasklist_lock
);
1537 * While in TASK_TRACED, we were considered "frozen enough".
1538 * Now that we woke up, it's crucial if we're supposed to be
1539 * frozen that we freeze now before running anything substantial.
1544 * We are back. Now reacquire the siglock before touching
1545 * last_siginfo, so that we are sure to have synchronized with
1546 * any signal-sending on another CPU that wants to examine it.
1548 spin_lock_irq(¤t
->sighand
->siglock
);
1549 current
->last_siginfo
= NULL
;
1552 * Queued signals ignored us while we were stopped for tracing.
1553 * So check for any that we should take before resuming user mode.
1554 * This sets TIF_SIGPENDING, but never clears it.
1556 recalc_sigpending_tsk(current
);
1559 void ptrace_notify(int exit_code
)
1563 BUG_ON((exit_code
& (0x7f | ~0xffff)) != SIGTRAP
);
1565 memset(&info
, 0, sizeof info
);
1566 info
.si_signo
= SIGTRAP
;
1567 info
.si_code
= exit_code
;
1568 info
.si_pid
= task_pid_vnr(current
);
1569 info
.si_uid
= current
->uid
;
1571 /* Let the debugger run. */
1572 spin_lock_irq(¤t
->sighand
->siglock
);
1573 ptrace_stop(exit_code
, 1, &info
);
1574 spin_unlock_irq(¤t
->sighand
->siglock
);
1578 finish_stop(int stop_count
)
1581 * If there are no other threads in the group, or if there is
1582 * a group stop in progress and we are the last to stop,
1583 * report to the parent. When ptraced, every thread reports itself.
1585 if (stop_count
== 0 || (current
->ptrace
& PT_PTRACED
)) {
1586 read_lock(&tasklist_lock
);
1587 do_notify_parent_cldstop(current
, CLD_STOPPED
);
1588 read_unlock(&tasklist_lock
);
1593 } while (try_to_freeze());
1595 * Now we don't run again until continued.
1597 current
->exit_code
= 0;
1601 * This performs the stopping for SIGSTOP and other stop signals.
1602 * We have to stop all threads in the thread group.
1603 * Returns nonzero if we've actually stopped and released the siglock.
1604 * Returns zero if we didn't stop and still hold the siglock.
1606 static int do_signal_stop(int signr
)
1608 struct signal_struct
*sig
= current
->signal
;
1611 if (sig
->group_stop_count
> 0) {
1613 * There is a group stop in progress. We don't need to
1614 * start another one.
1616 stop_count
= --sig
->group_stop_count
;
1618 struct task_struct
*t
;
1620 if (!likely(sig
->flags
& SIGNAL_STOP_DEQUEUED
) ||
1621 unlikely(signal_group_exit(sig
)))
1624 * There is no group stop already in progress.
1625 * We must initiate one now.
1627 sig
->group_exit_code
= signr
;
1630 for (t
= next_thread(current
); t
!= current
; t
= next_thread(t
))
1632 * Setting state to TASK_STOPPED for a group
1633 * stop is always done with the siglock held,
1634 * so this check has no races.
1636 if (!(t
->flags
& PF_EXITING
) &&
1637 !task_is_stopped_or_traced(t
)) {
1639 signal_wake_up(t
, 0);
1641 sig
->group_stop_count
= stop_count
;
1644 if (stop_count
== 0)
1645 sig
->flags
= SIGNAL_STOP_STOPPED
;
1646 current
->exit_code
= sig
->group_exit_code
;
1647 __set_current_state(TASK_STOPPED
);
1649 spin_unlock_irq(¤t
->sighand
->siglock
);
1650 finish_stop(stop_count
);
1654 static int ptrace_signal(int signr
, siginfo_t
*info
,
1655 struct pt_regs
*regs
, void *cookie
)
1657 if (!(current
->ptrace
& PT_PTRACED
))
1660 ptrace_signal_deliver(regs
, cookie
);
1662 /* Let the debugger run. */
1663 ptrace_stop(signr
, 0, info
);
1665 /* We're back. Did the debugger cancel the sig? */
1666 signr
= current
->exit_code
;
1670 current
->exit_code
= 0;
1672 /* Update the siginfo structure if the signal has
1673 changed. If the debugger wanted something
1674 specific in the siginfo structure then it should
1675 have updated *info via PTRACE_SETSIGINFO. */
1676 if (signr
!= info
->si_signo
) {
1677 info
->si_signo
= signr
;
1679 info
->si_code
= SI_USER
;
1680 info
->si_pid
= task_pid_vnr(current
->parent
);
1681 info
->si_uid
= current
->parent
->uid
;
1684 /* If the (new) signal is now blocked, requeue it. */
1685 if (sigismember(¤t
->blocked
, signr
)) {
1686 specific_send_sig_info(signr
, info
, current
);
1693 int get_signal_to_deliver(siginfo_t
*info
, struct k_sigaction
*return_ka
,
1694 struct pt_regs
*regs
, void *cookie
)
1696 struct sighand_struct
*sighand
= current
->sighand
;
1697 struct signal_struct
*signal
= current
->signal
;
1702 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1703 * While in TASK_STOPPED, we were considered "frozen enough".
1704 * Now that we woke up, it's crucial if we're supposed to be
1705 * frozen that we freeze now before running anything substantial.
1709 spin_lock_irq(&sighand
->siglock
);
1711 * Every stopped thread goes here after wakeup. Check to see if
1712 * we should notify the parent, prepare_signal(SIGCONT) encodes
1713 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
1715 if (unlikely(signal
->flags
& SIGNAL_CLD_MASK
)) {
1716 int why
= (signal
->flags
& SIGNAL_STOP_CONTINUED
)
1717 ? CLD_CONTINUED
: CLD_STOPPED
;
1718 signal
->flags
&= ~SIGNAL_CLD_MASK
;
1719 spin_unlock_irq(&sighand
->siglock
);
1721 read_lock(&tasklist_lock
);
1722 do_notify_parent_cldstop(current
->group_leader
, why
);
1723 read_unlock(&tasklist_lock
);
1728 struct k_sigaction
*ka
;
1730 if (unlikely(signal
->group_stop_count
> 0) &&
1734 signr
= dequeue_signal(current
, ¤t
->blocked
, info
);
1736 break; /* will return 0 */
1738 if (signr
!= SIGKILL
) {
1739 signr
= ptrace_signal(signr
, info
, regs
, cookie
);
1744 ka
= &sighand
->action
[signr
-1];
1745 if (ka
->sa
.sa_handler
== SIG_IGN
) /* Do nothing. */
1747 if (ka
->sa
.sa_handler
!= SIG_DFL
) {
1748 /* Run the handler. */
1751 if (ka
->sa
.sa_flags
& SA_ONESHOT
)
1752 ka
->sa
.sa_handler
= SIG_DFL
;
1754 break; /* will return non-zero "signr" value */
1758 * Now we are doing the default action for this signal.
1760 if (sig_kernel_ignore(signr
)) /* Default is nothing. */
1764 * Global init gets no signals it doesn't want.
1766 if (is_global_init(current
))
1769 if (sig_kernel_stop(signr
)) {
1771 * The default action is to stop all threads in
1772 * the thread group. The job control signals
1773 * do nothing in an orphaned pgrp, but SIGSTOP
1774 * always works. Note that siglock needs to be
1775 * dropped during the call to is_orphaned_pgrp()
1776 * because of lock ordering with tasklist_lock.
1777 * This allows an intervening SIGCONT to be posted.
1778 * We need to check for that and bail out if necessary.
1780 if (signr
!= SIGSTOP
) {
1781 spin_unlock_irq(&sighand
->siglock
);
1783 /* signals can be posted during this window */
1785 if (is_current_pgrp_orphaned())
1788 spin_lock_irq(&sighand
->siglock
);
1791 if (likely(do_signal_stop(signr
))) {
1792 /* It released the siglock. */
1797 * We didn't actually stop, due to a race
1798 * with SIGCONT or something like that.
1803 spin_unlock_irq(&sighand
->siglock
);
1806 * Anything else is fatal, maybe with a core dump.
1808 current
->flags
|= PF_SIGNALED
;
1810 if (sig_kernel_coredump(signr
)) {
1811 if (print_fatal_signals
)
1812 print_fatal_signal(regs
, signr
);
1814 * If it was able to dump core, this kills all
1815 * other threads in the group and synchronizes with
1816 * their demise. If we lost the race with another
1817 * thread getting here, it set group_exit_code
1818 * first and our do_group_exit call below will use
1819 * that value and ignore the one we pass it.
1821 do_coredump((long)signr
, signr
, regs
);
1825 * Death signals, no core dump.
1827 do_group_exit(signr
);
1830 spin_unlock_irq(&sighand
->siglock
);
1834 void exit_signals(struct task_struct
*tsk
)
1837 struct task_struct
*t
;
1839 if (thread_group_empty(tsk
) || signal_group_exit(tsk
->signal
)) {
1840 tsk
->flags
|= PF_EXITING
;
1844 spin_lock_irq(&tsk
->sighand
->siglock
);
1846 * From now this task is not visible for group-wide signals,
1847 * see wants_signal(), do_signal_stop().
1849 tsk
->flags
|= PF_EXITING
;
1850 if (!signal_pending(tsk
))
1853 /* It could be that __group_complete_signal() choose us to
1854 * notify about group-wide signal. Another thread should be
1855 * woken now to take the signal since we will not.
1857 for (t
= tsk
; (t
= next_thread(t
)) != tsk
; )
1858 if (!signal_pending(t
) && !(t
->flags
& PF_EXITING
))
1859 recalc_sigpending_and_wake(t
);
1861 if (unlikely(tsk
->signal
->group_stop_count
) &&
1862 !--tsk
->signal
->group_stop_count
) {
1863 tsk
->signal
->flags
= SIGNAL_STOP_STOPPED
;
1867 spin_unlock_irq(&tsk
->sighand
->siglock
);
1869 if (unlikely(group_stop
)) {
1870 read_lock(&tasklist_lock
);
1871 do_notify_parent_cldstop(tsk
, CLD_STOPPED
);
1872 read_unlock(&tasklist_lock
);
1876 EXPORT_SYMBOL(recalc_sigpending
);
1877 EXPORT_SYMBOL_GPL(dequeue_signal
);
1878 EXPORT_SYMBOL(flush_signals
);
1879 EXPORT_SYMBOL(force_sig
);
1880 EXPORT_SYMBOL(kill_proc
);
1881 EXPORT_SYMBOL(ptrace_notify
);
1882 EXPORT_SYMBOL(send_sig
);
1883 EXPORT_SYMBOL(send_sig_info
);
1884 EXPORT_SYMBOL(sigprocmask
);
1885 EXPORT_SYMBOL(block_all_signals
);
1886 EXPORT_SYMBOL(unblock_all_signals
);
1890 * System call entry points.
1893 asmlinkage
long sys_restart_syscall(void)
1895 struct restart_block
*restart
= ¤t_thread_info()->restart_block
;
1896 return restart
->fn(restart
);
1899 long do_no_restart_syscall(struct restart_block
*param
)
1905 * We don't need to get the kernel lock - this is all local to this
1906 * particular thread.. (and that's good, because this is _heavily_
1907 * used by various programs)
1911 * This is also useful for kernel threads that want to temporarily
1912 * (or permanently) block certain signals.
1914 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1915 * interface happily blocks "unblockable" signals like SIGKILL
1918 int sigprocmask(int how
, sigset_t
*set
, sigset_t
*oldset
)
1922 spin_lock_irq(¤t
->sighand
->siglock
);
1924 *oldset
= current
->blocked
;
1929 sigorsets(¤t
->blocked
, ¤t
->blocked
, set
);
1932 signandsets(¤t
->blocked
, ¤t
->blocked
, set
);
1935 current
->blocked
= *set
;
1940 recalc_sigpending();
1941 spin_unlock_irq(¤t
->sighand
->siglock
);
1947 sys_rt_sigprocmask(int how
, sigset_t __user
*set
, sigset_t __user
*oset
, size_t sigsetsize
)
1949 int error
= -EINVAL
;
1950 sigset_t old_set
, new_set
;
1952 /* XXX: Don't preclude handling different sized sigset_t's. */
1953 if (sigsetsize
!= sizeof(sigset_t
))
1958 if (copy_from_user(&new_set
, set
, sizeof(*set
)))
1960 sigdelsetmask(&new_set
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
1962 error
= sigprocmask(how
, &new_set
, &old_set
);
1968 spin_lock_irq(¤t
->sighand
->siglock
);
1969 old_set
= current
->blocked
;
1970 spin_unlock_irq(¤t
->sighand
->siglock
);
1974 if (copy_to_user(oset
, &old_set
, sizeof(*oset
)))
1982 long do_sigpending(void __user
*set
, unsigned long sigsetsize
)
1984 long error
= -EINVAL
;
1987 if (sigsetsize
> sizeof(sigset_t
))
1990 spin_lock_irq(¤t
->sighand
->siglock
);
1991 sigorsets(&pending
, ¤t
->pending
.signal
,
1992 ¤t
->signal
->shared_pending
.signal
);
1993 spin_unlock_irq(¤t
->sighand
->siglock
);
1995 /* Outside the lock because only this thread touches it. */
1996 sigandsets(&pending
, ¤t
->blocked
, &pending
);
1999 if (!copy_to_user(set
, &pending
, sigsetsize
))
2007 sys_rt_sigpending(sigset_t __user
*set
, size_t sigsetsize
)
2009 return do_sigpending(set
, sigsetsize
);
2012 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2014 int copy_siginfo_to_user(siginfo_t __user
*to
, siginfo_t
*from
)
2018 if (!access_ok (VERIFY_WRITE
, to
, sizeof(siginfo_t
)))
2020 if (from
->si_code
< 0)
2021 return __copy_to_user(to
, from
, sizeof(siginfo_t
))
2024 * If you change siginfo_t structure, please be sure
2025 * this code is fixed accordingly.
2026 * Please remember to update the signalfd_copyinfo() function
2027 * inside fs/signalfd.c too, in case siginfo_t changes.
2028 * It should never copy any pad contained in the structure
2029 * to avoid security leaks, but must copy the generic
2030 * 3 ints plus the relevant union member.
2032 err
= __put_user(from
->si_signo
, &to
->si_signo
);
2033 err
|= __put_user(from
->si_errno
, &to
->si_errno
);
2034 err
|= __put_user((short)from
->si_code
, &to
->si_code
);
2035 switch (from
->si_code
& __SI_MASK
) {
2037 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2038 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2041 err
|= __put_user(from
->si_tid
, &to
->si_tid
);
2042 err
|= __put_user(from
->si_overrun
, &to
->si_overrun
);
2043 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2046 err
|= __put_user(from
->si_band
, &to
->si_band
);
2047 err
|= __put_user(from
->si_fd
, &to
->si_fd
);
2050 err
|= __put_user(from
->si_addr
, &to
->si_addr
);
2051 #ifdef __ARCH_SI_TRAPNO
2052 err
|= __put_user(from
->si_trapno
, &to
->si_trapno
);
2056 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2057 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2058 err
|= __put_user(from
->si_status
, &to
->si_status
);
2059 err
|= __put_user(from
->si_utime
, &to
->si_utime
);
2060 err
|= __put_user(from
->si_stime
, &to
->si_stime
);
2062 case __SI_RT
: /* This is not generated by the kernel as of now. */
2063 case __SI_MESGQ
: /* But this is */
2064 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2065 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2066 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2068 default: /* this is just in case for now ... */
2069 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2070 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2079 sys_rt_sigtimedwait(const sigset_t __user
*uthese
,
2080 siginfo_t __user
*uinfo
,
2081 const struct timespec __user
*uts
,
2090 /* XXX: Don't preclude handling different sized sigset_t's. */
2091 if (sigsetsize
!= sizeof(sigset_t
))
2094 if (copy_from_user(&these
, uthese
, sizeof(these
)))
2098 * Invert the set of allowed signals to get those we
2101 sigdelsetmask(&these
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2105 if (copy_from_user(&ts
, uts
, sizeof(ts
)))
2107 if (ts
.tv_nsec
>= 1000000000L || ts
.tv_nsec
< 0
2112 spin_lock_irq(¤t
->sighand
->siglock
);
2113 sig
= dequeue_signal(current
, &these
, &info
);
2115 timeout
= MAX_SCHEDULE_TIMEOUT
;
2117 timeout
= (timespec_to_jiffies(&ts
)
2118 + (ts
.tv_sec
|| ts
.tv_nsec
));
2121 /* None ready -- temporarily unblock those we're
2122 * interested while we are sleeping in so that we'll
2123 * be awakened when they arrive. */
2124 current
->real_blocked
= current
->blocked
;
2125 sigandsets(¤t
->blocked
, ¤t
->blocked
, &these
);
2126 recalc_sigpending();
2127 spin_unlock_irq(¤t
->sighand
->siglock
);
2129 timeout
= schedule_timeout_interruptible(timeout
);
2131 spin_lock_irq(¤t
->sighand
->siglock
);
2132 sig
= dequeue_signal(current
, &these
, &info
);
2133 current
->blocked
= current
->real_blocked
;
2134 siginitset(¤t
->real_blocked
, 0);
2135 recalc_sigpending();
2138 spin_unlock_irq(¤t
->sighand
->siglock
);
2143 if (copy_siginfo_to_user(uinfo
, &info
))
2156 sys_kill(int pid
, int sig
)
2158 struct siginfo info
;
2160 info
.si_signo
= sig
;
2162 info
.si_code
= SI_USER
;
2163 info
.si_pid
= task_tgid_vnr(current
);
2164 info
.si_uid
= current
->uid
;
2166 return kill_something_info(sig
, &info
, pid
);
2169 static int do_tkill(int tgid
, int pid
, int sig
)
2172 struct siginfo info
;
2173 struct task_struct
*p
;
2174 unsigned long flags
;
2177 info
.si_signo
= sig
;
2179 info
.si_code
= SI_TKILL
;
2180 info
.si_pid
= task_tgid_vnr(current
);
2181 info
.si_uid
= current
->uid
;
2184 p
= find_task_by_vpid(pid
);
2185 if (p
&& (tgid
<= 0 || task_tgid_vnr(p
) == tgid
)) {
2186 error
= check_kill_permission(sig
, &info
, p
);
2188 * The null signal is a permissions and process existence
2189 * probe. No signal is actually delivered.
2191 * If lock_task_sighand() fails we pretend the task dies
2192 * after receiving the signal. The window is tiny, and the
2193 * signal is private anyway.
2195 if (!error
&& sig
&& lock_task_sighand(p
, &flags
)) {
2196 error
= specific_send_sig_info(sig
, &info
, p
);
2197 unlock_task_sighand(p
, &flags
);
2206 * sys_tgkill - send signal to one specific thread
2207 * @tgid: the thread group ID of the thread
2208 * @pid: the PID of the thread
2209 * @sig: signal to be sent
2211 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2212 * exists but it's not belonging to the target process anymore. This
2213 * method solves the problem of threads exiting and PIDs getting reused.
2215 asmlinkage
long sys_tgkill(int tgid
, int pid
, int sig
)
2217 /* This is only valid for single tasks */
2218 if (pid
<= 0 || tgid
<= 0)
2221 return do_tkill(tgid
, pid
, sig
);
2225 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2228 sys_tkill(int pid
, int sig
)
2230 /* This is only valid for single tasks */
2234 return do_tkill(0, pid
, sig
);
2238 sys_rt_sigqueueinfo(int pid
, int sig
, siginfo_t __user
*uinfo
)
2242 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
2245 /* Not even root can pretend to send signals from the kernel.
2246 Nor can they impersonate a kill(), which adds source info. */
2247 if (info
.si_code
>= 0)
2249 info
.si_signo
= sig
;
2251 /* POSIX.1b doesn't mention process groups. */
2252 return kill_proc_info(sig
, &info
, pid
);
2255 int do_sigaction(int sig
, struct k_sigaction
*act
, struct k_sigaction
*oact
)
2257 struct task_struct
*t
= current
;
2258 struct k_sigaction
*k
;
2261 if (!valid_signal(sig
) || sig
< 1 || (act
&& sig_kernel_only(sig
)))
2264 k
= &t
->sighand
->action
[sig
-1];
2266 spin_lock_irq(¤t
->sighand
->siglock
);
2271 sigdelsetmask(&act
->sa
.sa_mask
,
2272 sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2276 * "Setting a signal action to SIG_IGN for a signal that is
2277 * pending shall cause the pending signal to be discarded,
2278 * whether or not it is blocked."
2280 * "Setting a signal action to SIG_DFL for a signal that is
2281 * pending and whose default action is to ignore the signal
2282 * (for example, SIGCHLD), shall cause the pending signal to
2283 * be discarded, whether or not it is blocked"
2285 if (__sig_ignored(t
, sig
)) {
2287 sigaddset(&mask
, sig
);
2288 rm_from_queue_full(&mask
, &t
->signal
->shared_pending
);
2290 rm_from_queue_full(&mask
, &t
->pending
);
2292 } while (t
!= current
);
2296 spin_unlock_irq(¤t
->sighand
->siglock
);
2301 do_sigaltstack (const stack_t __user
*uss
, stack_t __user
*uoss
, unsigned long sp
)
2307 oss
.ss_sp
= (void __user
*) current
->sas_ss_sp
;
2308 oss
.ss_size
= current
->sas_ss_size
;
2309 oss
.ss_flags
= sas_ss_flags(sp
);
2318 if (!access_ok(VERIFY_READ
, uss
, sizeof(*uss
))
2319 || __get_user(ss_sp
, &uss
->ss_sp
)
2320 || __get_user(ss_flags
, &uss
->ss_flags
)
2321 || __get_user(ss_size
, &uss
->ss_size
))
2325 if (on_sig_stack(sp
))
2331 * Note - this code used to test ss_flags incorrectly
2332 * old code may have been written using ss_flags==0
2333 * to mean ss_flags==SS_ONSTACK (as this was the only
2334 * way that worked) - this fix preserves that older
2337 if (ss_flags
!= SS_DISABLE
&& ss_flags
!= SS_ONSTACK
&& ss_flags
!= 0)
2340 if (ss_flags
== SS_DISABLE
) {
2345 if (ss_size
< MINSIGSTKSZ
)
2349 current
->sas_ss_sp
= (unsigned long) ss_sp
;
2350 current
->sas_ss_size
= ss_size
;
2355 if (copy_to_user(uoss
, &oss
, sizeof(oss
)))
2364 #ifdef __ARCH_WANT_SYS_SIGPENDING
2367 sys_sigpending(old_sigset_t __user
*set
)
2369 return do_sigpending(set
, sizeof(*set
));
2374 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2375 /* Some platforms have their own version with special arguments others
2376 support only sys_rt_sigprocmask. */
2379 sys_sigprocmask(int how
, old_sigset_t __user
*set
, old_sigset_t __user
*oset
)
2382 old_sigset_t old_set
, new_set
;
2386 if (copy_from_user(&new_set
, set
, sizeof(*set
)))
2388 new_set
&= ~(sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2390 spin_lock_irq(¤t
->sighand
->siglock
);
2391 old_set
= current
->blocked
.sig
[0];
2399 sigaddsetmask(¤t
->blocked
, new_set
);
2402 sigdelsetmask(¤t
->blocked
, new_set
);
2405 current
->blocked
.sig
[0] = new_set
;
2409 recalc_sigpending();
2410 spin_unlock_irq(¤t
->sighand
->siglock
);
2416 old_set
= current
->blocked
.sig
[0];
2419 if (copy_to_user(oset
, &old_set
, sizeof(*oset
)))
2426 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2428 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2430 sys_rt_sigaction(int sig
,
2431 const struct sigaction __user
*act
,
2432 struct sigaction __user
*oact
,
2435 struct k_sigaction new_sa
, old_sa
;
2438 /* XXX: Don't preclude handling different sized sigset_t's. */
2439 if (sigsetsize
!= sizeof(sigset_t
))
2443 if (copy_from_user(&new_sa
.sa
, act
, sizeof(new_sa
.sa
)))
2447 ret
= do_sigaction(sig
, act
? &new_sa
: NULL
, oact
? &old_sa
: NULL
);
2450 if (copy_to_user(oact
, &old_sa
.sa
, sizeof(old_sa
.sa
)))
2456 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2458 #ifdef __ARCH_WANT_SYS_SGETMASK
2461 * For backwards compatibility. Functionality superseded by sigprocmask.
2467 return current
->blocked
.sig
[0];
2471 sys_ssetmask(int newmask
)
2475 spin_lock_irq(¤t
->sighand
->siglock
);
2476 old
= current
->blocked
.sig
[0];
2478 siginitset(¤t
->blocked
, newmask
& ~(sigmask(SIGKILL
)|
2480 recalc_sigpending();
2481 spin_unlock_irq(¤t
->sighand
->siglock
);
2485 #endif /* __ARCH_WANT_SGETMASK */
2487 #ifdef __ARCH_WANT_SYS_SIGNAL
2489 * For backwards compatibility. Functionality superseded by sigaction.
2491 asmlinkage
unsigned long
2492 sys_signal(int sig
, __sighandler_t handler
)
2494 struct k_sigaction new_sa
, old_sa
;
2497 new_sa
.sa
.sa_handler
= handler
;
2498 new_sa
.sa
.sa_flags
= SA_ONESHOT
| SA_NOMASK
;
2499 sigemptyset(&new_sa
.sa
.sa_mask
);
2501 ret
= do_sigaction(sig
, &new_sa
, &old_sa
);
2503 return ret
? ret
: (unsigned long)old_sa
.sa
.sa_handler
;
2505 #endif /* __ARCH_WANT_SYS_SIGNAL */
2507 #ifdef __ARCH_WANT_SYS_PAUSE
2512 current
->state
= TASK_INTERRUPTIBLE
;
2514 return -ERESTARTNOHAND
;
2519 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2520 asmlinkage
long sys_rt_sigsuspend(sigset_t __user
*unewset
, size_t sigsetsize
)
2524 /* XXX: Don't preclude handling different sized sigset_t's. */
2525 if (sigsetsize
!= sizeof(sigset_t
))
2528 if (copy_from_user(&newset
, unewset
, sizeof(newset
)))
2530 sigdelsetmask(&newset
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2532 spin_lock_irq(¤t
->sighand
->siglock
);
2533 current
->saved_sigmask
= current
->blocked
;
2534 current
->blocked
= newset
;
2535 recalc_sigpending();
2536 spin_unlock_irq(¤t
->sighand
->siglock
);
2538 current
->state
= TASK_INTERRUPTIBLE
;
2540 set_thread_flag(TIF_RESTORE_SIGMASK
);
2541 return -ERESTARTNOHAND
;
2543 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2545 __attribute__((weak
)) const char *arch_vma_name(struct vm_area_struct
*vma
)
2550 void __init
signals_init(void)
2552 sigqueue_cachep
= KMEM_CACHE(sigqueue
, SLAB_PANIC
);