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
)
538 if (!valid_signal(sig
))
541 if (info
!= SEND_SIG_NOINFO
&& (is_si_special(info
) || SI_FROMKERNEL(info
)))
544 error
= audit_signal_info(sig
, t
); /* Let audit system see the signal */
548 if (((sig
!= SIGCONT
) || (task_session_nr(current
) != task_session_nr(t
)))
549 && (current
->euid
^ t
->suid
) && (current
->euid
^ t
->uid
)
550 && (current
->uid
^ t
->suid
) && (current
->uid
^ t
->uid
)
551 && !capable(CAP_KILL
))
554 return security_task_kill(t
, info
, sig
, 0);
558 static void do_notify_parent_cldstop(struct task_struct
*tsk
, int why
);
561 * Handle magic process-wide effects of stop/continue signals.
562 * Unlike the signal actions, these happen immediately at signal-generation
563 * time regardless of blocking, ignoring, or handling. This does the
564 * actual continuing for SIGCONT, but not the actual stopping for stop
565 * signals. The process stop is done as a signal action for SIG_DFL.
567 static void handle_stop_signal(int sig
, struct task_struct
*p
)
569 struct signal_struct
*signal
= p
->signal
;
570 struct task_struct
*t
;
572 if (signal
->flags
& SIGNAL_GROUP_EXIT
)
574 * The process is in the middle of dying already.
578 if (sig_kernel_stop(sig
)) {
580 * This is a stop signal. Remove SIGCONT from all queues.
582 rm_from_queue(sigmask(SIGCONT
), &signal
->shared_pending
);
585 rm_from_queue(sigmask(SIGCONT
), &t
->pending
);
586 } while_each_thread(p
, t
);
587 } else if (sig
== SIGCONT
) {
590 * Remove all stop signals from all queues,
591 * and wake all threads.
593 rm_from_queue(SIG_KERNEL_STOP_MASK
, &signal
->shared_pending
);
597 rm_from_queue(SIG_KERNEL_STOP_MASK
, &t
->pending
);
599 * If there is a handler for SIGCONT, we must make
600 * sure that no thread returns to user mode before
601 * we post the signal, in case it was the only
602 * thread eligible to run the signal handler--then
603 * it must not do anything between resuming and
604 * running the handler. With the TIF_SIGPENDING
605 * flag set, the thread will pause and acquire the
606 * siglock that we hold now and until we've queued
607 * the pending signal.
609 * Wake up the stopped thread _after_ setting
612 state
= __TASK_STOPPED
;
613 if (sig_user_defined(t
, SIGCONT
) && !sigismember(&t
->blocked
, SIGCONT
)) {
614 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
615 state
|= TASK_INTERRUPTIBLE
;
617 wake_up_state(t
, state
);
618 } while_each_thread(p
, t
);
621 * Notify the parent with CLD_CONTINUED if we were stopped.
623 * If we were in the middle of a group stop, we pretend it
624 * was already finished, and then continued. Since SIGCHLD
625 * doesn't queue we report only CLD_STOPPED, as if the next
626 * CLD_CONTINUED was dropped.
629 if (signal
->flags
& SIGNAL_STOP_STOPPED
)
630 why
|= SIGNAL_CLD_CONTINUED
;
631 else if (signal
->group_stop_count
)
632 why
|= SIGNAL_CLD_STOPPED
;
635 signal
->flags
= why
| SIGNAL_STOP_CONTINUED
;
636 signal
->group_stop_count
= 0;
637 signal
->group_exit_code
= 0;
640 * We are not stopped, but there could be a stop
641 * signal in the middle of being processed after
642 * being removed from the queue. Clear that too.
644 signal
->flags
&= ~SIGNAL_STOP_DEQUEUED
;
650 * Test if P wants to take SIG. After we've checked all threads with this,
651 * it's equivalent to finding no threads not blocking SIG. Any threads not
652 * blocking SIG were ruled out because they are not running and already
653 * have pending signals. Such threads will dequeue from the shared queue
654 * as soon as they're available, so putting the signal on the shared queue
655 * will be equivalent to sending it to one such thread.
657 static inline int wants_signal(int sig
, struct task_struct
*p
)
659 if (sigismember(&p
->blocked
, sig
))
661 if (p
->flags
& PF_EXITING
)
665 if (task_is_stopped_or_traced(p
))
667 return task_curr(p
) || !signal_pending(p
);
670 static void complete_signal(int sig
, struct task_struct
*p
, int group
)
672 struct signal_struct
*signal
= p
->signal
;
673 struct task_struct
*t
;
676 * Now find a thread we can wake up to take the signal off the queue.
678 * If the main thread wants the signal, it gets first crack.
679 * Probably the least surprising to the average bear.
681 if (wants_signal(sig
, p
))
683 else if (!group
|| thread_group_empty(p
))
685 * There is just one thread and it does not need to be woken.
686 * It will dequeue unblocked signals before it runs again.
691 * Otherwise try to find a suitable thread.
693 t
= signal
->curr_target
;
694 while (!wants_signal(sig
, t
)) {
696 if (t
== signal
->curr_target
)
698 * No thread needs to be woken.
699 * Any eligible threads will see
700 * the signal in the queue soon.
704 signal
->curr_target
= t
;
708 * Found a killable thread. If the signal will be fatal,
709 * then start taking the whole group down immediately.
711 if (sig_fatal(p
, sig
) && !(signal
->flags
& SIGNAL_GROUP_EXIT
) &&
712 !sigismember(&t
->real_blocked
, sig
) &&
713 (sig
== SIGKILL
|| !(t
->ptrace
& PT_PTRACED
))) {
715 * This signal will be fatal to the whole group.
717 if (!sig_kernel_coredump(sig
)) {
719 * Start a group exit and wake everybody up.
720 * This way we don't have other threads
721 * running and doing things after a slower
722 * thread has the fatal signal pending.
724 signal
->flags
= SIGNAL_GROUP_EXIT
;
725 signal
->group_exit_code
= sig
;
726 signal
->group_stop_count
= 0;
729 sigaddset(&t
->pending
.signal
, SIGKILL
);
730 signal_wake_up(t
, 1);
731 } while_each_thread(p
, t
);
737 * The signal is already in the shared-pending queue.
738 * Tell the chosen thread to wake up and dequeue it.
740 signal_wake_up(t
, sig
== SIGKILL
);
744 static inline int legacy_queue(struct sigpending
*signals
, int sig
)
746 return (sig
< SIGRTMIN
) && sigismember(&signals
->signal
, sig
);
749 static int send_signal(int sig
, struct siginfo
*info
, struct task_struct
*t
,
752 struct sigpending
*pending
;
755 assert_spin_locked(&t
->sighand
->siglock
);
756 handle_stop_signal(sig
, t
);
758 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
760 * Short-circuit ignored signals and support queuing
761 * exactly one non-rt signal, so that we can get more
762 * detailed information about the cause of the signal.
764 if (sig_ignored(t
, sig
) || legacy_queue(pending
, sig
))
768 * Deliver the signal to listening signalfds. This must be called
769 * with the sighand lock held.
771 signalfd_notify(t
, sig
);
774 * fast-pathed signals for kernel-internal things like SIGSTOP
777 if (info
== SEND_SIG_FORCED
)
780 /* Real-time signals must be queued if sent by sigqueue, or
781 some other real-time mechanism. It is implementation
782 defined whether kill() does so. We attempt to do so, on
783 the principle of least surprise, but since kill is not
784 allowed to fail with EAGAIN when low on memory we just
785 make sure at least one signal gets delivered and don't
786 pass on the info struct. */
788 q
= __sigqueue_alloc(t
, GFP_ATOMIC
, (sig
< SIGRTMIN
&&
789 (is_si_special(info
) ||
790 info
->si_code
>= 0)));
792 list_add_tail(&q
->list
, &pending
->list
);
793 switch ((unsigned long) info
) {
794 case (unsigned long) SEND_SIG_NOINFO
:
795 q
->info
.si_signo
= sig
;
796 q
->info
.si_errno
= 0;
797 q
->info
.si_code
= SI_USER
;
798 q
->info
.si_pid
= task_pid_vnr(current
);
799 q
->info
.si_uid
= current
->uid
;
801 case (unsigned long) SEND_SIG_PRIV
:
802 q
->info
.si_signo
= sig
;
803 q
->info
.si_errno
= 0;
804 q
->info
.si_code
= SI_KERNEL
;
809 copy_siginfo(&q
->info
, info
);
812 } else if (!is_si_special(info
)) {
813 if (sig
>= SIGRTMIN
&& info
->si_code
!= SI_USER
)
815 * Queue overflow, abort. We may abort if the signal was rt
816 * and sent by user using something other than kill().
822 sigaddset(&pending
->signal
, sig
);
823 complete_signal(sig
, t
, group
);
827 int print_fatal_signals
;
829 static void print_fatal_signal(struct pt_regs
*regs
, int signr
)
831 printk("%s/%d: potentially unexpected fatal signal %d.\n",
832 current
->comm
, task_pid_nr(current
), signr
);
834 #if defined(__i386__) && !defined(__arch_um__)
835 printk("code at %08lx: ", regs
->ip
);
838 for (i
= 0; i
< 16; i
++) {
841 __get_user(insn
, (unsigned char *)(regs
->ip
+ i
));
842 printk("%02x ", insn
);
850 static int __init
setup_print_fatal_signals(char *str
)
852 get_option (&str
, &print_fatal_signals
);
857 __setup("print-fatal-signals=", setup_print_fatal_signals
);
860 __group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
862 return send_signal(sig
, info
, p
, 1);
866 specific_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
868 return send_signal(sig
, info
, t
, 0);
872 * Force a signal that the process can't ignore: if necessary
873 * we unblock the signal and change any SIG_IGN to SIG_DFL.
875 * Note: If we unblock the signal, we always reset it to SIG_DFL,
876 * since we do not want to have a signal handler that was blocked
877 * be invoked when user space had explicitly blocked it.
879 * We don't want to have recursive SIGSEGV's etc, for example.
882 force_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
884 unsigned long int flags
;
885 int ret
, blocked
, ignored
;
886 struct k_sigaction
*action
;
888 spin_lock_irqsave(&t
->sighand
->siglock
, flags
);
889 action
= &t
->sighand
->action
[sig
-1];
890 ignored
= action
->sa
.sa_handler
== SIG_IGN
;
891 blocked
= sigismember(&t
->blocked
, sig
);
892 if (blocked
|| ignored
) {
893 action
->sa
.sa_handler
= SIG_DFL
;
895 sigdelset(&t
->blocked
, sig
);
896 recalc_sigpending_and_wake(t
);
899 ret
= specific_send_sig_info(sig
, info
, t
);
900 spin_unlock_irqrestore(&t
->sighand
->siglock
, flags
);
906 force_sig_specific(int sig
, struct task_struct
*t
)
908 force_sig_info(sig
, SEND_SIG_FORCED
, t
);
912 * Nuke all other threads in the group.
914 void zap_other_threads(struct task_struct
*p
)
916 struct task_struct
*t
;
918 p
->signal
->group_stop_count
= 0;
920 for (t
= next_thread(p
); t
!= p
; t
= next_thread(t
)) {
922 * Don't bother with already dead threads
927 /* SIGKILL will be handled before any pending SIGSTOP */
928 sigaddset(&t
->pending
.signal
, SIGKILL
);
929 signal_wake_up(t
, 1);
933 int __fatal_signal_pending(struct task_struct
*tsk
)
935 return sigismember(&tsk
->pending
.signal
, SIGKILL
);
937 EXPORT_SYMBOL(__fatal_signal_pending
);
939 struct sighand_struct
*lock_task_sighand(struct task_struct
*tsk
, unsigned long *flags
)
941 struct sighand_struct
*sighand
;
945 sighand
= rcu_dereference(tsk
->sighand
);
946 if (unlikely(sighand
== NULL
))
949 spin_lock_irqsave(&sighand
->siglock
, *flags
);
950 if (likely(sighand
== tsk
->sighand
))
952 spin_unlock_irqrestore(&sighand
->siglock
, *flags
);
959 int group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
964 ret
= check_kill_permission(sig
, info
, p
);
968 if (lock_task_sighand(p
, &flags
)) {
969 ret
= __group_send_sig_info(sig
, info
, p
);
970 unlock_task_sighand(p
, &flags
);
978 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
979 * control characters do (^C, ^Z etc)
982 int __kill_pgrp_info(int sig
, struct siginfo
*info
, struct pid
*pgrp
)
984 struct task_struct
*p
= NULL
;
989 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
990 int err
= group_send_sig_info(sig
, info
, p
);
993 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
994 return success
? 0 : retval
;
997 int kill_pid_info(int sig
, struct siginfo
*info
, struct pid
*pid
)
1000 struct task_struct
*p
;
1004 p
= pid_task(pid
, PIDTYPE_PID
);
1006 error
= group_send_sig_info(sig
, info
, p
);
1007 if (unlikely(error
== -ESRCH
))
1009 * The task was unhashed in between, try again.
1010 * If it is dead, pid_task() will return NULL,
1011 * if we race with de_thread() it will find the
1022 kill_proc_info(int sig
, struct siginfo
*info
, pid_t pid
)
1026 error
= kill_pid_info(sig
, info
, find_vpid(pid
));
1031 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1032 int kill_pid_info_as_uid(int sig
, struct siginfo
*info
, struct pid
*pid
,
1033 uid_t uid
, uid_t euid
, u32 secid
)
1036 struct task_struct
*p
;
1038 if (!valid_signal(sig
))
1041 read_lock(&tasklist_lock
);
1042 p
= pid_task(pid
, PIDTYPE_PID
);
1047 if ((info
== SEND_SIG_NOINFO
|| (!is_si_special(info
) && SI_FROMUSER(info
)))
1048 && (euid
!= p
->suid
) && (euid
!= p
->uid
)
1049 && (uid
!= p
->suid
) && (uid
!= p
->uid
)) {
1053 ret
= security_task_kill(p
, info
, sig
, secid
);
1056 if (sig
&& p
->sighand
) {
1057 unsigned long flags
;
1058 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1059 ret
= __group_send_sig_info(sig
, info
, p
);
1060 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1063 read_unlock(&tasklist_lock
);
1066 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid
);
1069 * kill_something_info() interprets pid in interesting ways just like kill(2).
1071 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1072 * is probably wrong. Should make it like BSD or SYSV.
1075 static int kill_something_info(int sig
, struct siginfo
*info
, int pid
)
1081 ret
= kill_pid_info(sig
, info
, find_vpid(pid
));
1086 read_lock(&tasklist_lock
);
1088 ret
= __kill_pgrp_info(sig
, info
,
1089 pid
? find_vpid(-pid
) : task_pgrp(current
));
1091 int retval
= 0, count
= 0;
1092 struct task_struct
* p
;
1094 for_each_process(p
) {
1095 if (p
->pid
> 1 && !same_thread_group(p
, current
)) {
1096 int err
= group_send_sig_info(sig
, info
, p
);
1102 ret
= count
? retval
: -ESRCH
;
1104 read_unlock(&tasklist_lock
);
1110 * These are for backward compatibility with the rest of the kernel source.
1114 * The caller must ensure the task can't exit.
1117 send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1120 unsigned long flags
;
1123 * Make sure legacy kernel users don't send in bad values
1124 * (normal paths check this in check_kill_permission).
1126 if (!valid_signal(sig
))
1129 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1130 ret
= specific_send_sig_info(sig
, info
, p
);
1131 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1135 #define __si_special(priv) \
1136 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1139 send_sig(int sig
, struct task_struct
*p
, int priv
)
1141 return send_sig_info(sig
, __si_special(priv
), p
);
1145 force_sig(int sig
, struct task_struct
*p
)
1147 force_sig_info(sig
, SEND_SIG_PRIV
, p
);
1151 * When things go south during signal handling, we
1152 * will force a SIGSEGV. And if the signal that caused
1153 * the problem was already a SIGSEGV, we'll want to
1154 * make sure we don't even try to deliver the signal..
1157 force_sigsegv(int sig
, struct task_struct
*p
)
1159 if (sig
== SIGSEGV
) {
1160 unsigned long flags
;
1161 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1162 p
->sighand
->action
[sig
- 1].sa
.sa_handler
= SIG_DFL
;
1163 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1165 force_sig(SIGSEGV
, p
);
1169 int kill_pgrp(struct pid
*pid
, int sig
, int priv
)
1173 read_lock(&tasklist_lock
);
1174 ret
= __kill_pgrp_info(sig
, __si_special(priv
), pid
);
1175 read_unlock(&tasklist_lock
);
1179 EXPORT_SYMBOL(kill_pgrp
);
1181 int kill_pid(struct pid
*pid
, int sig
, int priv
)
1183 return kill_pid_info(sig
, __si_special(priv
), pid
);
1185 EXPORT_SYMBOL(kill_pid
);
1188 kill_proc(pid_t pid
, int sig
, int priv
)
1193 ret
= kill_pid_info(sig
, __si_special(priv
), find_pid(pid
));
1199 * These functions support sending signals using preallocated sigqueue
1200 * structures. This is needed "because realtime applications cannot
1201 * afford to lose notifications of asynchronous events, like timer
1202 * expirations or I/O completions". In the case of Posix Timers
1203 * we allocate the sigqueue structure from the timer_create. If this
1204 * allocation fails we are able to report the failure to the application
1205 * with an EAGAIN error.
1208 struct sigqueue
*sigqueue_alloc(void)
1212 if ((q
= __sigqueue_alloc(current
, GFP_KERNEL
, 0)))
1213 q
->flags
|= SIGQUEUE_PREALLOC
;
1217 void sigqueue_free(struct sigqueue
*q
)
1219 unsigned long flags
;
1220 spinlock_t
*lock
= ¤t
->sighand
->siglock
;
1222 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1224 * If the signal is still pending remove it from the
1225 * pending queue. We must hold ->siglock while testing
1226 * q->list to serialize with collect_signal().
1228 spin_lock_irqsave(lock
, flags
);
1229 if (!list_empty(&q
->list
))
1230 list_del_init(&q
->list
);
1231 spin_unlock_irqrestore(lock
, flags
);
1233 q
->flags
&= ~SIGQUEUE_PREALLOC
;
1237 int send_sigqueue(struct sigqueue
*q
, struct task_struct
*t
, int group
)
1239 int sig
= q
->info
.si_signo
;
1240 struct sigpending
*pending
;
1241 unsigned long flags
;
1244 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1247 if (!likely(lock_task_sighand(t
, &flags
)))
1250 handle_stop_signal(sig
, t
);
1253 if (sig_ignored(t
, sig
))
1257 if (unlikely(!list_empty(&q
->list
))) {
1259 * If an SI_TIMER entry is already queue just increment
1260 * the overrun count.
1262 BUG_ON(q
->info
.si_code
!= SI_TIMER
);
1263 q
->info
.si_overrun
++;
1267 signalfd_notify(t
, sig
);
1268 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
1269 list_add_tail(&q
->list
, &pending
->list
);
1270 sigaddset(&pending
->signal
, sig
);
1271 complete_signal(sig
, t
, group
);
1273 unlock_task_sighand(t
, &flags
);
1279 * Wake up any threads in the parent blocked in wait* syscalls.
1281 static inline void __wake_up_parent(struct task_struct
*p
,
1282 struct task_struct
*parent
)
1284 wake_up_interruptible_sync(&parent
->signal
->wait_chldexit
);
1288 * Let a parent know about the death of a child.
1289 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1292 void do_notify_parent(struct task_struct
*tsk
, int sig
)
1294 struct siginfo info
;
1295 unsigned long flags
;
1296 struct sighand_struct
*psig
;
1300 /* do_notify_parent_cldstop should have been called instead. */
1301 BUG_ON(task_is_stopped_or_traced(tsk
));
1303 BUG_ON(!tsk
->ptrace
&&
1304 (tsk
->group_leader
!= tsk
|| !thread_group_empty(tsk
)));
1306 info
.si_signo
= sig
;
1309 * we are under tasklist_lock here so our parent is tied to
1310 * us and cannot exit and release its namespace.
1312 * the only it can is to switch its nsproxy with sys_unshare,
1313 * bu uncharing pid namespaces is not allowed, so we'll always
1314 * see relevant namespace
1316 * write_lock() currently calls preempt_disable() which is the
1317 * same as rcu_read_lock(), but according to Oleg, this is not
1318 * correct to rely on this
1321 info
.si_pid
= task_pid_nr_ns(tsk
, tsk
->parent
->nsproxy
->pid_ns
);
1324 info
.si_uid
= tsk
->uid
;
1326 /* FIXME: find out whether or not this is supposed to be c*time. */
1327 info
.si_utime
= cputime_to_jiffies(cputime_add(tsk
->utime
,
1328 tsk
->signal
->utime
));
1329 info
.si_stime
= cputime_to_jiffies(cputime_add(tsk
->stime
,
1330 tsk
->signal
->stime
));
1332 info
.si_status
= tsk
->exit_code
& 0x7f;
1333 if (tsk
->exit_code
& 0x80)
1334 info
.si_code
= CLD_DUMPED
;
1335 else if (tsk
->exit_code
& 0x7f)
1336 info
.si_code
= CLD_KILLED
;
1338 info
.si_code
= CLD_EXITED
;
1339 info
.si_status
= tsk
->exit_code
>> 8;
1342 psig
= tsk
->parent
->sighand
;
1343 spin_lock_irqsave(&psig
->siglock
, flags
);
1344 if (!tsk
->ptrace
&& sig
== SIGCHLD
&&
1345 (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
||
1346 (psig
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDWAIT
))) {
1348 * We are exiting and our parent doesn't care. POSIX.1
1349 * defines special semantics for setting SIGCHLD to SIG_IGN
1350 * or setting the SA_NOCLDWAIT flag: we should be reaped
1351 * automatically and not left for our parent's wait4 call.
1352 * Rather than having the parent do it as a magic kind of
1353 * signal handler, we just set this to tell do_exit that we
1354 * can be cleaned up without becoming a zombie. Note that
1355 * we still call __wake_up_parent in this case, because a
1356 * blocked sys_wait4 might now return -ECHILD.
1358 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1359 * is implementation-defined: we do (if you don't want
1360 * it, just use SIG_IGN instead).
1362 tsk
->exit_signal
= -1;
1363 if (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
)
1366 if (valid_signal(sig
) && sig
> 0)
1367 __group_send_sig_info(sig
, &info
, tsk
->parent
);
1368 __wake_up_parent(tsk
, tsk
->parent
);
1369 spin_unlock_irqrestore(&psig
->siglock
, flags
);
1372 static void do_notify_parent_cldstop(struct task_struct
*tsk
, int why
)
1374 struct siginfo info
;
1375 unsigned long flags
;
1376 struct task_struct
*parent
;
1377 struct sighand_struct
*sighand
;
1379 if (tsk
->ptrace
& PT_PTRACED
)
1380 parent
= tsk
->parent
;
1382 tsk
= tsk
->group_leader
;
1383 parent
= tsk
->real_parent
;
1386 info
.si_signo
= SIGCHLD
;
1389 * see comment in do_notify_parent() abot the following 3 lines
1392 info
.si_pid
= task_pid_nr_ns(tsk
, tsk
->parent
->nsproxy
->pid_ns
);
1395 info
.si_uid
= tsk
->uid
;
1397 /* FIXME: find out whether or not this is supposed to be c*time. */
1398 info
.si_utime
= cputime_to_jiffies(tsk
->utime
);
1399 info
.si_stime
= cputime_to_jiffies(tsk
->stime
);
1404 info
.si_status
= SIGCONT
;
1407 info
.si_status
= tsk
->signal
->group_exit_code
& 0x7f;
1410 info
.si_status
= tsk
->exit_code
& 0x7f;
1416 sighand
= parent
->sighand
;
1417 spin_lock_irqsave(&sighand
->siglock
, flags
);
1418 if (sighand
->action
[SIGCHLD
-1].sa
.sa_handler
!= SIG_IGN
&&
1419 !(sighand
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDSTOP
))
1420 __group_send_sig_info(SIGCHLD
, &info
, parent
);
1422 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1424 __wake_up_parent(tsk
, parent
);
1425 spin_unlock_irqrestore(&sighand
->siglock
, flags
);
1428 static inline int may_ptrace_stop(void)
1430 if (!likely(current
->ptrace
& PT_PTRACED
))
1433 * Are we in the middle of do_coredump?
1434 * If so and our tracer is also part of the coredump stopping
1435 * is a deadlock situation, and pointless because our tracer
1436 * is dead so don't allow us to stop.
1437 * If SIGKILL was already sent before the caller unlocked
1438 * ->siglock we must see ->core_waiters != 0. Otherwise it
1439 * is safe to enter schedule().
1441 if (unlikely(current
->mm
->core_waiters
) &&
1442 unlikely(current
->mm
== current
->parent
->mm
))
1449 * Return nonzero if there is a SIGKILL that should be waking us up.
1450 * Called with the siglock held.
1452 static int sigkill_pending(struct task_struct
*tsk
)
1454 return ((sigismember(&tsk
->pending
.signal
, SIGKILL
) ||
1455 sigismember(&tsk
->signal
->shared_pending
.signal
, SIGKILL
)) &&
1456 !unlikely(sigismember(&tsk
->blocked
, SIGKILL
)));
1460 * This must be called with current->sighand->siglock held.
1462 * This should be the path for all ptrace stops.
1463 * We always set current->last_siginfo while stopped here.
1464 * That makes it a way to test a stopped process for
1465 * being ptrace-stopped vs being job-control-stopped.
1467 * If we actually decide not to stop at all because the tracer
1468 * is gone, we keep current->exit_code unless clear_code.
1470 static void ptrace_stop(int exit_code
, int clear_code
, siginfo_t
*info
)
1474 if (arch_ptrace_stop_needed(exit_code
, info
)) {
1476 * The arch code has something special to do before a
1477 * ptrace stop. This is allowed to block, e.g. for faults
1478 * on user stack pages. We can't keep the siglock while
1479 * calling arch_ptrace_stop, so we must release it now.
1480 * To preserve proper semantics, we must do this before
1481 * any signal bookkeeping like checking group_stop_count.
1482 * Meanwhile, a SIGKILL could come in before we retake the
1483 * siglock. That must prevent us from sleeping in TASK_TRACED.
1484 * So after regaining the lock, we must check for SIGKILL.
1486 spin_unlock_irq(¤t
->sighand
->siglock
);
1487 arch_ptrace_stop(exit_code
, info
);
1488 spin_lock_irq(¤t
->sighand
->siglock
);
1489 killed
= sigkill_pending(current
);
1493 * If there is a group stop in progress,
1494 * we must participate in the bookkeeping.
1496 if (current
->signal
->group_stop_count
> 0)
1497 --current
->signal
->group_stop_count
;
1499 current
->last_siginfo
= info
;
1500 current
->exit_code
= exit_code
;
1502 /* Let the debugger run. */
1503 __set_current_state(TASK_TRACED
);
1504 spin_unlock_irq(¤t
->sighand
->siglock
);
1505 read_lock(&tasklist_lock
);
1506 if (!unlikely(killed
) && may_ptrace_stop()) {
1507 do_notify_parent_cldstop(current
, CLD_TRAPPED
);
1508 read_unlock(&tasklist_lock
);
1512 * By the time we got the lock, our tracer went away.
1513 * Don't drop the lock yet, another tracer may come.
1515 __set_current_state(TASK_RUNNING
);
1517 current
->exit_code
= 0;
1518 read_unlock(&tasklist_lock
);
1522 * While in TASK_TRACED, we were considered "frozen enough".
1523 * Now that we woke up, it's crucial if we're supposed to be
1524 * frozen that we freeze now before running anything substantial.
1529 * We are back. Now reacquire the siglock before touching
1530 * last_siginfo, so that we are sure to have synchronized with
1531 * any signal-sending on another CPU that wants to examine it.
1533 spin_lock_irq(¤t
->sighand
->siglock
);
1534 current
->last_siginfo
= NULL
;
1537 * Queued signals ignored us while we were stopped for tracing.
1538 * So check for any that we should take before resuming user mode.
1539 * This sets TIF_SIGPENDING, but never clears it.
1541 recalc_sigpending_tsk(current
);
1544 void ptrace_notify(int exit_code
)
1548 BUG_ON((exit_code
& (0x7f | ~0xffff)) != SIGTRAP
);
1550 memset(&info
, 0, sizeof info
);
1551 info
.si_signo
= SIGTRAP
;
1552 info
.si_code
= exit_code
;
1553 info
.si_pid
= task_pid_vnr(current
);
1554 info
.si_uid
= current
->uid
;
1556 /* Let the debugger run. */
1557 spin_lock_irq(¤t
->sighand
->siglock
);
1558 ptrace_stop(exit_code
, 1, &info
);
1559 spin_unlock_irq(¤t
->sighand
->siglock
);
1563 finish_stop(int stop_count
)
1566 * If there are no other threads in the group, or if there is
1567 * a group stop in progress and we are the last to stop,
1568 * report to the parent. When ptraced, every thread reports itself.
1570 if (stop_count
== 0 || (current
->ptrace
& PT_PTRACED
)) {
1571 read_lock(&tasklist_lock
);
1572 do_notify_parent_cldstop(current
, CLD_STOPPED
);
1573 read_unlock(&tasklist_lock
);
1578 } while (try_to_freeze());
1580 * Now we don't run again until continued.
1582 current
->exit_code
= 0;
1586 * This performs the stopping for SIGSTOP and other stop signals.
1587 * We have to stop all threads in the thread group.
1588 * Returns nonzero if we've actually stopped and released the siglock.
1589 * Returns zero if we didn't stop and still hold the siglock.
1591 static int do_signal_stop(int signr
)
1593 struct signal_struct
*sig
= current
->signal
;
1596 if (sig
->group_stop_count
> 0) {
1598 * There is a group stop in progress. We don't need to
1599 * start another one.
1601 stop_count
= --sig
->group_stop_count
;
1603 struct task_struct
*t
;
1605 if (!likely(sig
->flags
& SIGNAL_STOP_DEQUEUED
) ||
1606 unlikely(signal_group_exit(sig
)))
1609 * There is no group stop already in progress.
1610 * We must initiate one now.
1612 sig
->group_exit_code
= signr
;
1615 for (t
= next_thread(current
); t
!= current
; t
= next_thread(t
))
1617 * Setting state to TASK_STOPPED for a group
1618 * stop is always done with the siglock held,
1619 * so this check has no races.
1621 if (!(t
->flags
& PF_EXITING
) &&
1622 !task_is_stopped_or_traced(t
)) {
1624 signal_wake_up(t
, 0);
1626 sig
->group_stop_count
= stop_count
;
1629 if (stop_count
== 0)
1630 sig
->flags
= SIGNAL_STOP_STOPPED
;
1631 current
->exit_code
= sig
->group_exit_code
;
1632 __set_current_state(TASK_STOPPED
);
1634 spin_unlock_irq(¤t
->sighand
->siglock
);
1635 finish_stop(stop_count
);
1639 static int ptrace_signal(int signr
, siginfo_t
*info
,
1640 struct pt_regs
*regs
, void *cookie
)
1642 if (!(current
->ptrace
& PT_PTRACED
))
1645 ptrace_signal_deliver(regs
, cookie
);
1647 /* Let the debugger run. */
1648 ptrace_stop(signr
, 0, info
);
1650 /* We're back. Did the debugger cancel the sig? */
1651 signr
= current
->exit_code
;
1655 current
->exit_code
= 0;
1657 /* Update the siginfo structure if the signal has
1658 changed. If the debugger wanted something
1659 specific in the siginfo structure then it should
1660 have updated *info via PTRACE_SETSIGINFO. */
1661 if (signr
!= info
->si_signo
) {
1662 info
->si_signo
= signr
;
1664 info
->si_code
= SI_USER
;
1665 info
->si_pid
= task_pid_vnr(current
->parent
);
1666 info
->si_uid
= current
->parent
->uid
;
1669 /* If the (new) signal is now blocked, requeue it. */
1670 if (sigismember(¤t
->blocked
, signr
)) {
1671 specific_send_sig_info(signr
, info
, current
);
1678 int get_signal_to_deliver(siginfo_t
*info
, struct k_sigaction
*return_ka
,
1679 struct pt_regs
*regs
, void *cookie
)
1681 struct sighand_struct
*sighand
= current
->sighand
;
1682 struct signal_struct
*signal
= current
->signal
;
1687 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1688 * While in TASK_STOPPED, we were considered "frozen enough".
1689 * Now that we woke up, it's crucial if we're supposed to be
1690 * frozen that we freeze now before running anything substantial.
1694 spin_lock_irq(&sighand
->siglock
);
1696 if (unlikely(signal
->flags
& SIGNAL_CLD_MASK
)) {
1697 int why
= (signal
->flags
& SIGNAL_STOP_CONTINUED
)
1698 ? CLD_CONTINUED
: CLD_STOPPED
;
1699 signal
->flags
&= ~SIGNAL_CLD_MASK
;
1700 spin_unlock_irq(&sighand
->siglock
);
1702 read_lock(&tasklist_lock
);
1703 do_notify_parent_cldstop(current
->group_leader
, why
);
1704 read_unlock(&tasklist_lock
);
1709 struct k_sigaction
*ka
;
1711 if (unlikely(signal
->group_stop_count
> 0) &&
1715 signr
= dequeue_signal(current
, ¤t
->blocked
, info
);
1717 break; /* will return 0 */
1719 if (signr
!= SIGKILL
) {
1720 signr
= ptrace_signal(signr
, info
, regs
, cookie
);
1725 ka
= &sighand
->action
[signr
-1];
1726 if (ka
->sa
.sa_handler
== SIG_IGN
) /* Do nothing. */
1728 if (ka
->sa
.sa_handler
!= SIG_DFL
) {
1729 /* Run the handler. */
1732 if (ka
->sa
.sa_flags
& SA_ONESHOT
)
1733 ka
->sa
.sa_handler
= SIG_DFL
;
1735 break; /* will return non-zero "signr" value */
1739 * Now we are doing the default action for this signal.
1741 if (sig_kernel_ignore(signr
)) /* Default is nothing. */
1745 * Global init gets no signals it doesn't want.
1747 if (is_global_init(current
))
1750 if (sig_kernel_stop(signr
)) {
1752 * The default action is to stop all threads in
1753 * the thread group. The job control signals
1754 * do nothing in an orphaned pgrp, but SIGSTOP
1755 * always works. Note that siglock needs to be
1756 * dropped during the call to is_orphaned_pgrp()
1757 * because of lock ordering with tasklist_lock.
1758 * This allows an intervening SIGCONT to be posted.
1759 * We need to check for that and bail out if necessary.
1761 if (signr
!= SIGSTOP
) {
1762 spin_unlock_irq(&sighand
->siglock
);
1764 /* signals can be posted during this window */
1766 if (is_current_pgrp_orphaned())
1769 spin_lock_irq(&sighand
->siglock
);
1772 if (likely(do_signal_stop(signr
))) {
1773 /* It released the siglock. */
1778 * We didn't actually stop, due to a race
1779 * with SIGCONT or something like that.
1784 spin_unlock_irq(&sighand
->siglock
);
1787 * Anything else is fatal, maybe with a core dump.
1789 current
->flags
|= PF_SIGNALED
;
1790 if ((signr
!= SIGKILL
) && print_fatal_signals
)
1791 print_fatal_signal(regs
, signr
);
1792 if (sig_kernel_coredump(signr
)) {
1794 * If it was able to dump core, this kills all
1795 * other threads in the group and synchronizes with
1796 * their demise. If we lost the race with another
1797 * thread getting here, it set group_exit_code
1798 * first and our do_group_exit call below will use
1799 * that value and ignore the one we pass it.
1801 do_coredump((long)signr
, signr
, regs
);
1805 * Death signals, no core dump.
1807 do_group_exit(signr
);
1810 spin_unlock_irq(&sighand
->siglock
);
1814 void exit_signals(struct task_struct
*tsk
)
1817 struct task_struct
*t
;
1819 if (thread_group_empty(tsk
) || signal_group_exit(tsk
->signal
)) {
1820 tsk
->flags
|= PF_EXITING
;
1824 spin_lock_irq(&tsk
->sighand
->siglock
);
1826 * From now this task is not visible for group-wide signals,
1827 * see wants_signal(), do_signal_stop().
1829 tsk
->flags
|= PF_EXITING
;
1830 if (!signal_pending(tsk
))
1833 /* It could be that __group_complete_signal() choose us to
1834 * notify about group-wide signal. Another thread should be
1835 * woken now to take the signal since we will not.
1837 for (t
= tsk
; (t
= next_thread(t
)) != tsk
; )
1838 if (!signal_pending(t
) && !(t
->flags
& PF_EXITING
))
1839 recalc_sigpending_and_wake(t
);
1841 if (unlikely(tsk
->signal
->group_stop_count
) &&
1842 !--tsk
->signal
->group_stop_count
) {
1843 tsk
->signal
->flags
= SIGNAL_STOP_STOPPED
;
1847 spin_unlock_irq(&tsk
->sighand
->siglock
);
1849 if (unlikely(group_stop
)) {
1850 read_lock(&tasklist_lock
);
1851 do_notify_parent_cldstop(tsk
, CLD_STOPPED
);
1852 read_unlock(&tasklist_lock
);
1856 EXPORT_SYMBOL(recalc_sigpending
);
1857 EXPORT_SYMBOL_GPL(dequeue_signal
);
1858 EXPORT_SYMBOL(flush_signals
);
1859 EXPORT_SYMBOL(force_sig
);
1860 EXPORT_SYMBOL(kill_proc
);
1861 EXPORT_SYMBOL(ptrace_notify
);
1862 EXPORT_SYMBOL(send_sig
);
1863 EXPORT_SYMBOL(send_sig_info
);
1864 EXPORT_SYMBOL(sigprocmask
);
1865 EXPORT_SYMBOL(block_all_signals
);
1866 EXPORT_SYMBOL(unblock_all_signals
);
1870 * System call entry points.
1873 asmlinkage
long sys_restart_syscall(void)
1875 struct restart_block
*restart
= ¤t_thread_info()->restart_block
;
1876 return restart
->fn(restart
);
1879 long do_no_restart_syscall(struct restart_block
*param
)
1885 * We don't need to get the kernel lock - this is all local to this
1886 * particular thread.. (and that's good, because this is _heavily_
1887 * used by various programs)
1891 * This is also useful for kernel threads that want to temporarily
1892 * (or permanently) block certain signals.
1894 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1895 * interface happily blocks "unblockable" signals like SIGKILL
1898 int sigprocmask(int how
, sigset_t
*set
, sigset_t
*oldset
)
1902 spin_lock_irq(¤t
->sighand
->siglock
);
1904 *oldset
= current
->blocked
;
1909 sigorsets(¤t
->blocked
, ¤t
->blocked
, set
);
1912 signandsets(¤t
->blocked
, ¤t
->blocked
, set
);
1915 current
->blocked
= *set
;
1920 recalc_sigpending();
1921 spin_unlock_irq(¤t
->sighand
->siglock
);
1927 sys_rt_sigprocmask(int how
, sigset_t __user
*set
, sigset_t __user
*oset
, size_t sigsetsize
)
1929 int error
= -EINVAL
;
1930 sigset_t old_set
, new_set
;
1932 /* XXX: Don't preclude handling different sized sigset_t's. */
1933 if (sigsetsize
!= sizeof(sigset_t
))
1938 if (copy_from_user(&new_set
, set
, sizeof(*set
)))
1940 sigdelsetmask(&new_set
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
1942 error
= sigprocmask(how
, &new_set
, &old_set
);
1948 spin_lock_irq(¤t
->sighand
->siglock
);
1949 old_set
= current
->blocked
;
1950 spin_unlock_irq(¤t
->sighand
->siglock
);
1954 if (copy_to_user(oset
, &old_set
, sizeof(*oset
)))
1962 long do_sigpending(void __user
*set
, unsigned long sigsetsize
)
1964 long error
= -EINVAL
;
1967 if (sigsetsize
> sizeof(sigset_t
))
1970 spin_lock_irq(¤t
->sighand
->siglock
);
1971 sigorsets(&pending
, ¤t
->pending
.signal
,
1972 ¤t
->signal
->shared_pending
.signal
);
1973 spin_unlock_irq(¤t
->sighand
->siglock
);
1975 /* Outside the lock because only this thread touches it. */
1976 sigandsets(&pending
, ¤t
->blocked
, &pending
);
1979 if (!copy_to_user(set
, &pending
, sigsetsize
))
1987 sys_rt_sigpending(sigset_t __user
*set
, size_t sigsetsize
)
1989 return do_sigpending(set
, sigsetsize
);
1992 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
1994 int copy_siginfo_to_user(siginfo_t __user
*to
, siginfo_t
*from
)
1998 if (!access_ok (VERIFY_WRITE
, to
, sizeof(siginfo_t
)))
2000 if (from
->si_code
< 0)
2001 return __copy_to_user(to
, from
, sizeof(siginfo_t
))
2004 * If you change siginfo_t structure, please be sure
2005 * this code is fixed accordingly.
2006 * Please remember to update the signalfd_copyinfo() function
2007 * inside fs/signalfd.c too, in case siginfo_t changes.
2008 * It should never copy any pad contained in the structure
2009 * to avoid security leaks, but must copy the generic
2010 * 3 ints plus the relevant union member.
2012 err
= __put_user(from
->si_signo
, &to
->si_signo
);
2013 err
|= __put_user(from
->si_errno
, &to
->si_errno
);
2014 err
|= __put_user((short)from
->si_code
, &to
->si_code
);
2015 switch (from
->si_code
& __SI_MASK
) {
2017 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2018 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2021 err
|= __put_user(from
->si_tid
, &to
->si_tid
);
2022 err
|= __put_user(from
->si_overrun
, &to
->si_overrun
);
2023 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2026 err
|= __put_user(from
->si_band
, &to
->si_band
);
2027 err
|= __put_user(from
->si_fd
, &to
->si_fd
);
2030 err
|= __put_user(from
->si_addr
, &to
->si_addr
);
2031 #ifdef __ARCH_SI_TRAPNO
2032 err
|= __put_user(from
->si_trapno
, &to
->si_trapno
);
2036 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2037 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2038 err
|= __put_user(from
->si_status
, &to
->si_status
);
2039 err
|= __put_user(from
->si_utime
, &to
->si_utime
);
2040 err
|= __put_user(from
->si_stime
, &to
->si_stime
);
2042 case __SI_RT
: /* This is not generated by the kernel as of now. */
2043 case __SI_MESGQ
: /* But this is */
2044 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2045 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2046 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2048 default: /* this is just in case for now ... */
2049 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2050 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2059 sys_rt_sigtimedwait(const sigset_t __user
*uthese
,
2060 siginfo_t __user
*uinfo
,
2061 const struct timespec __user
*uts
,
2070 /* XXX: Don't preclude handling different sized sigset_t's. */
2071 if (sigsetsize
!= sizeof(sigset_t
))
2074 if (copy_from_user(&these
, uthese
, sizeof(these
)))
2078 * Invert the set of allowed signals to get those we
2081 sigdelsetmask(&these
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2085 if (copy_from_user(&ts
, uts
, sizeof(ts
)))
2087 if (ts
.tv_nsec
>= 1000000000L || ts
.tv_nsec
< 0
2092 spin_lock_irq(¤t
->sighand
->siglock
);
2093 sig
= dequeue_signal(current
, &these
, &info
);
2095 timeout
= MAX_SCHEDULE_TIMEOUT
;
2097 timeout
= (timespec_to_jiffies(&ts
)
2098 + (ts
.tv_sec
|| ts
.tv_nsec
));
2101 /* None ready -- temporarily unblock those we're
2102 * interested while we are sleeping in so that we'll
2103 * be awakened when they arrive. */
2104 current
->real_blocked
= current
->blocked
;
2105 sigandsets(¤t
->blocked
, ¤t
->blocked
, &these
);
2106 recalc_sigpending();
2107 spin_unlock_irq(¤t
->sighand
->siglock
);
2109 timeout
= schedule_timeout_interruptible(timeout
);
2111 spin_lock_irq(¤t
->sighand
->siglock
);
2112 sig
= dequeue_signal(current
, &these
, &info
);
2113 current
->blocked
= current
->real_blocked
;
2114 siginitset(¤t
->real_blocked
, 0);
2115 recalc_sigpending();
2118 spin_unlock_irq(¤t
->sighand
->siglock
);
2123 if (copy_siginfo_to_user(uinfo
, &info
))
2136 sys_kill(int pid
, int sig
)
2138 struct siginfo info
;
2140 info
.si_signo
= sig
;
2142 info
.si_code
= SI_USER
;
2143 info
.si_pid
= task_tgid_vnr(current
);
2144 info
.si_uid
= current
->uid
;
2146 return kill_something_info(sig
, &info
, pid
);
2149 static int do_tkill(int tgid
, int pid
, int sig
)
2152 struct siginfo info
;
2153 struct task_struct
*p
;
2154 unsigned long flags
;
2157 info
.si_signo
= sig
;
2159 info
.si_code
= SI_TKILL
;
2160 info
.si_pid
= task_tgid_vnr(current
);
2161 info
.si_uid
= current
->uid
;
2164 p
= find_task_by_vpid(pid
);
2165 if (p
&& (tgid
<= 0 || task_tgid_vnr(p
) == tgid
)) {
2166 error
= check_kill_permission(sig
, &info
, p
);
2168 * The null signal is a permissions and process existence
2169 * probe. No signal is actually delivered.
2171 * If lock_task_sighand() fails we pretend the task dies
2172 * after receiving the signal. The window is tiny, and the
2173 * signal is private anyway.
2175 if (!error
&& sig
&& lock_task_sighand(p
, &flags
)) {
2176 error
= specific_send_sig_info(sig
, &info
, p
);
2177 unlock_task_sighand(p
, &flags
);
2186 * sys_tgkill - send signal to one specific thread
2187 * @tgid: the thread group ID of the thread
2188 * @pid: the PID of the thread
2189 * @sig: signal to be sent
2191 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2192 * exists but it's not belonging to the target process anymore. This
2193 * method solves the problem of threads exiting and PIDs getting reused.
2195 asmlinkage
long sys_tgkill(int tgid
, int pid
, int sig
)
2197 /* This is only valid for single tasks */
2198 if (pid
<= 0 || tgid
<= 0)
2201 return do_tkill(tgid
, pid
, sig
);
2205 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2208 sys_tkill(int pid
, int sig
)
2210 /* This is only valid for single tasks */
2214 return do_tkill(0, pid
, sig
);
2218 sys_rt_sigqueueinfo(int pid
, int sig
, siginfo_t __user
*uinfo
)
2222 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
2225 /* Not even root can pretend to send signals from the kernel.
2226 Nor can they impersonate a kill(), which adds source info. */
2227 if (info
.si_code
>= 0)
2229 info
.si_signo
= sig
;
2231 /* POSIX.1b doesn't mention process groups. */
2232 return kill_proc_info(sig
, &info
, pid
);
2235 int do_sigaction(int sig
, struct k_sigaction
*act
, struct k_sigaction
*oact
)
2237 struct task_struct
*t
= current
;
2238 struct k_sigaction
*k
;
2241 if (!valid_signal(sig
) || sig
< 1 || (act
&& sig_kernel_only(sig
)))
2244 k
= &t
->sighand
->action
[sig
-1];
2246 spin_lock_irq(¤t
->sighand
->siglock
);
2251 sigdelsetmask(&act
->sa
.sa_mask
,
2252 sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2256 * "Setting a signal action to SIG_IGN for a signal that is
2257 * pending shall cause the pending signal to be discarded,
2258 * whether or not it is blocked."
2260 * "Setting a signal action to SIG_DFL for a signal that is
2261 * pending and whose default action is to ignore the signal
2262 * (for example, SIGCHLD), shall cause the pending signal to
2263 * be discarded, whether or not it is blocked"
2265 if (__sig_ignored(t
, sig
)) {
2267 sigaddset(&mask
, sig
);
2268 rm_from_queue_full(&mask
, &t
->signal
->shared_pending
);
2270 rm_from_queue_full(&mask
, &t
->pending
);
2272 } while (t
!= current
);
2276 spin_unlock_irq(¤t
->sighand
->siglock
);
2281 do_sigaltstack (const stack_t __user
*uss
, stack_t __user
*uoss
, unsigned long sp
)
2287 oss
.ss_sp
= (void __user
*) current
->sas_ss_sp
;
2288 oss
.ss_size
= current
->sas_ss_size
;
2289 oss
.ss_flags
= sas_ss_flags(sp
);
2298 if (!access_ok(VERIFY_READ
, uss
, sizeof(*uss
))
2299 || __get_user(ss_sp
, &uss
->ss_sp
)
2300 || __get_user(ss_flags
, &uss
->ss_flags
)
2301 || __get_user(ss_size
, &uss
->ss_size
))
2305 if (on_sig_stack(sp
))
2311 * Note - this code used to test ss_flags incorrectly
2312 * old code may have been written using ss_flags==0
2313 * to mean ss_flags==SS_ONSTACK (as this was the only
2314 * way that worked) - this fix preserves that older
2317 if (ss_flags
!= SS_DISABLE
&& ss_flags
!= SS_ONSTACK
&& ss_flags
!= 0)
2320 if (ss_flags
== SS_DISABLE
) {
2325 if (ss_size
< MINSIGSTKSZ
)
2329 current
->sas_ss_sp
= (unsigned long) ss_sp
;
2330 current
->sas_ss_size
= ss_size
;
2335 if (copy_to_user(uoss
, &oss
, sizeof(oss
)))
2344 #ifdef __ARCH_WANT_SYS_SIGPENDING
2347 sys_sigpending(old_sigset_t __user
*set
)
2349 return do_sigpending(set
, sizeof(*set
));
2354 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2355 /* Some platforms have their own version with special arguments others
2356 support only sys_rt_sigprocmask. */
2359 sys_sigprocmask(int how
, old_sigset_t __user
*set
, old_sigset_t __user
*oset
)
2362 old_sigset_t old_set
, new_set
;
2366 if (copy_from_user(&new_set
, set
, sizeof(*set
)))
2368 new_set
&= ~(sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2370 spin_lock_irq(¤t
->sighand
->siglock
);
2371 old_set
= current
->blocked
.sig
[0];
2379 sigaddsetmask(¤t
->blocked
, new_set
);
2382 sigdelsetmask(¤t
->blocked
, new_set
);
2385 current
->blocked
.sig
[0] = new_set
;
2389 recalc_sigpending();
2390 spin_unlock_irq(¤t
->sighand
->siglock
);
2396 old_set
= current
->blocked
.sig
[0];
2399 if (copy_to_user(oset
, &old_set
, sizeof(*oset
)))
2406 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2408 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2410 sys_rt_sigaction(int sig
,
2411 const struct sigaction __user
*act
,
2412 struct sigaction __user
*oact
,
2415 struct k_sigaction new_sa
, old_sa
;
2418 /* XXX: Don't preclude handling different sized sigset_t's. */
2419 if (sigsetsize
!= sizeof(sigset_t
))
2423 if (copy_from_user(&new_sa
.sa
, act
, sizeof(new_sa
.sa
)))
2427 ret
= do_sigaction(sig
, act
? &new_sa
: NULL
, oact
? &old_sa
: NULL
);
2430 if (copy_to_user(oact
, &old_sa
.sa
, sizeof(old_sa
.sa
)))
2436 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2438 #ifdef __ARCH_WANT_SYS_SGETMASK
2441 * For backwards compatibility. Functionality superseded by sigprocmask.
2447 return current
->blocked
.sig
[0];
2451 sys_ssetmask(int newmask
)
2455 spin_lock_irq(¤t
->sighand
->siglock
);
2456 old
= current
->blocked
.sig
[0];
2458 siginitset(¤t
->blocked
, newmask
& ~(sigmask(SIGKILL
)|
2460 recalc_sigpending();
2461 spin_unlock_irq(¤t
->sighand
->siglock
);
2465 #endif /* __ARCH_WANT_SGETMASK */
2467 #ifdef __ARCH_WANT_SYS_SIGNAL
2469 * For backwards compatibility. Functionality superseded by sigaction.
2471 asmlinkage
unsigned long
2472 sys_signal(int sig
, __sighandler_t handler
)
2474 struct k_sigaction new_sa
, old_sa
;
2477 new_sa
.sa
.sa_handler
= handler
;
2478 new_sa
.sa
.sa_flags
= SA_ONESHOT
| SA_NOMASK
;
2479 sigemptyset(&new_sa
.sa
.sa_mask
);
2481 ret
= do_sigaction(sig
, &new_sa
, &old_sa
);
2483 return ret
? ret
: (unsigned long)old_sa
.sa
.sa_handler
;
2485 #endif /* __ARCH_WANT_SYS_SIGNAL */
2487 #ifdef __ARCH_WANT_SYS_PAUSE
2492 current
->state
= TASK_INTERRUPTIBLE
;
2494 return -ERESTARTNOHAND
;
2499 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2500 asmlinkage
long sys_rt_sigsuspend(sigset_t __user
*unewset
, size_t sigsetsize
)
2504 /* XXX: Don't preclude handling different sized sigset_t's. */
2505 if (sigsetsize
!= sizeof(sigset_t
))
2508 if (copy_from_user(&newset
, unewset
, sizeof(newset
)))
2510 sigdelsetmask(&newset
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2512 spin_lock_irq(¤t
->sighand
->siglock
);
2513 current
->saved_sigmask
= current
->blocked
;
2514 current
->blocked
= newset
;
2515 recalc_sigpending();
2516 spin_unlock_irq(¤t
->sighand
->siglock
);
2518 current
->state
= TASK_INTERRUPTIBLE
;
2520 set_thread_flag(TIF_RESTORE_SIGMASK
);
2521 return -ERESTARTNOHAND
;
2523 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2525 __attribute__((weak
)) const char *arch_vma_name(struct vm_area_struct
*vma
)
2530 void __init
signals_init(void)
2532 sigqueue_cachep
= KMEM_CACHE(sigqueue
, SLAB_PANIC
);