2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/slab.h>
14 #include <linux/export.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/coredump.h>
21 #include <linux/security.h>
22 #include <linux/syscalls.h>
23 #include <linux/ptrace.h>
24 #include <linux/signal.h>
25 #include <linux/signalfd.h>
26 #include <linux/ratelimit.h>
27 #include <linux/tracehook.h>
28 #include <linux/capability.h>
29 #include <linux/freezer.h>
30 #include <linux/pid_namespace.h>
31 #include <linux/nsproxy.h>
32 #include <linux/user_namespace.h>
33 #include <linux/uprobes.h>
34 #include <linux/compat.h>
35 #include <linux/cn_proc.h>
36 #include <linux/compiler.h>
38 #define CREATE_TRACE_POINTS
39 #include <trace/events/signal.h>
41 #include <asm/param.h>
42 #include <asm/uaccess.h>
43 #include <asm/unistd.h>
44 #include <asm/siginfo.h>
45 #include <asm/cacheflush.h>
46 #include "audit.h" /* audit_signal_info() */
49 * SLAB caches for signal bits.
52 static struct kmem_cache
*sigqueue_cachep
;
54 int print_fatal_signals __read_mostly
;
56 static void __user
*sig_handler(struct task_struct
*t
, int sig
)
58 return t
->sighand
->action
[sig
- 1].sa
.sa_handler
;
61 static int sig_handler_ignored(void __user
*handler
, int sig
)
63 /* Is it explicitly or implicitly ignored? */
64 return handler
== SIG_IGN
||
65 (handler
== SIG_DFL
&& sig_kernel_ignore(sig
));
68 static int sig_task_ignored(struct task_struct
*t
, int sig
, bool force
)
72 handler
= sig_handler(t
, sig
);
74 if (unlikely(t
->signal
->flags
& SIGNAL_UNKILLABLE
) &&
75 handler
== SIG_DFL
&& !(force
&& sig_kernel_only(sig
)))
78 return sig_handler_ignored(handler
, sig
);
81 static int sig_ignored(struct task_struct
*t
, int sig
, bool force
)
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
88 if (sigismember(&t
->blocked
, sig
) || sigismember(&t
->real_blocked
, sig
))
92 * Tracers may want to know about even ignored signal unless it
93 * is SIGKILL which can't be reported anyway but can be ignored
94 * by SIGNAL_UNKILLABLE task.
96 if (t
->ptrace
&& sig
!= SIGKILL
)
99 return sig_task_ignored(t
, sig
, force
);
103 * Re-calculate pending state from the set of locally pending
104 * signals, globally pending signals, and blocked signals.
106 static inline int has_pending_signals(sigset_t
*signal
, sigset_t
*blocked
)
111 switch (_NSIG_WORDS
) {
113 for (i
= _NSIG_WORDS
, ready
= 0; --i
>= 0 ;)
114 ready
|= signal
->sig
[i
] &~ blocked
->sig
[i
];
117 case 4: ready
= signal
->sig
[3] &~ blocked
->sig
[3];
118 ready
|= signal
->sig
[2] &~ blocked
->sig
[2];
119 ready
|= signal
->sig
[1] &~ blocked
->sig
[1];
120 ready
|= signal
->sig
[0] &~ blocked
->sig
[0];
123 case 2: ready
= signal
->sig
[1] &~ blocked
->sig
[1];
124 ready
|= signal
->sig
[0] &~ blocked
->sig
[0];
127 case 1: ready
= signal
->sig
[0] &~ blocked
->sig
[0];
132 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
134 static int recalc_sigpending_tsk(struct task_struct
*t
)
136 if ((t
->jobctl
& JOBCTL_PENDING_MASK
) ||
137 PENDING(&t
->pending
, &t
->blocked
) ||
138 PENDING(&t
->signal
->shared_pending
, &t
->blocked
)) {
139 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
143 * We must never clear the flag in another thread, or in current
144 * when it's possible the current syscall is returning -ERESTART*.
145 * So we don't clear it here, and only callers who know they should do.
151 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
152 * This is superfluous when called on current, the wakeup is a harmless no-op.
154 void recalc_sigpending_and_wake(struct task_struct
*t
)
156 if (recalc_sigpending_tsk(t
))
157 signal_wake_up(t
, 0);
160 void recalc_sigpending(void)
162 if (!recalc_sigpending_tsk(current
) && !freezing(current
))
163 clear_thread_flag(TIF_SIGPENDING
);
167 /* Given the mask, find the first available signal that should be serviced. */
169 #define SYNCHRONOUS_MASK \
170 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
171 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
173 int next_signal(struct sigpending
*pending
, sigset_t
*mask
)
175 unsigned long i
, *s
, *m
, x
;
178 s
= pending
->signal
.sig
;
182 * Handle the first word specially: it contains the
183 * synchronous signals that need to be dequeued first.
187 if (x
& SYNCHRONOUS_MASK
)
188 x
&= SYNCHRONOUS_MASK
;
193 switch (_NSIG_WORDS
) {
195 for (i
= 1; i
< _NSIG_WORDS
; ++i
) {
199 sig
= ffz(~x
) + i
*_NSIG_BPW
+ 1;
208 sig
= ffz(~x
) + _NSIG_BPW
+ 1;
219 static inline void print_dropped_signal(int sig
)
221 static DEFINE_RATELIMIT_STATE(ratelimit_state
, 5 * HZ
, 10);
223 if (!print_fatal_signals
)
226 if (!__ratelimit(&ratelimit_state
))
229 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
230 current
->comm
, current
->pid
, sig
);
234 * task_set_jobctl_pending - set jobctl pending bits
236 * @mask: pending bits to set
238 * Clear @mask from @task->jobctl. @mask must be subset of
239 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
240 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
241 * cleared. If @task is already being killed or exiting, this function
245 * Must be called with @task->sighand->siglock held.
248 * %true if @mask is set, %false if made noop because @task was dying.
250 bool task_set_jobctl_pending(struct task_struct
*task
, unsigned long mask
)
252 BUG_ON(mask
& ~(JOBCTL_PENDING_MASK
| JOBCTL_STOP_CONSUME
|
253 JOBCTL_STOP_SIGMASK
| JOBCTL_TRAPPING
));
254 BUG_ON((mask
& JOBCTL_TRAPPING
) && !(mask
& JOBCTL_PENDING_MASK
));
256 if (unlikely(fatal_signal_pending(task
) || (task
->flags
& PF_EXITING
)))
259 if (mask
& JOBCTL_STOP_SIGMASK
)
260 task
->jobctl
&= ~JOBCTL_STOP_SIGMASK
;
262 task
->jobctl
|= mask
;
267 * task_clear_jobctl_trapping - clear jobctl trapping bit
270 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
271 * Clear it and wake up the ptracer. Note that we don't need any further
272 * locking. @task->siglock guarantees that @task->parent points to the
276 * Must be called with @task->sighand->siglock held.
278 void task_clear_jobctl_trapping(struct task_struct
*task
)
280 if (unlikely(task
->jobctl
& JOBCTL_TRAPPING
)) {
281 task
->jobctl
&= ~JOBCTL_TRAPPING
;
282 smp_mb(); /* advised by wake_up_bit() */
283 wake_up_bit(&task
->jobctl
, JOBCTL_TRAPPING_BIT
);
288 * task_clear_jobctl_pending - clear jobctl pending bits
290 * @mask: pending bits to clear
292 * Clear @mask from @task->jobctl. @mask must be subset of
293 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
294 * STOP bits are cleared together.
296 * If clearing of @mask leaves no stop or trap pending, this function calls
297 * task_clear_jobctl_trapping().
300 * Must be called with @task->sighand->siglock held.
302 void task_clear_jobctl_pending(struct task_struct
*task
, unsigned long mask
)
304 BUG_ON(mask
& ~JOBCTL_PENDING_MASK
);
306 if (mask
& JOBCTL_STOP_PENDING
)
307 mask
|= JOBCTL_STOP_CONSUME
| JOBCTL_STOP_DEQUEUED
;
309 task
->jobctl
&= ~mask
;
311 if (!(task
->jobctl
& JOBCTL_PENDING_MASK
))
312 task_clear_jobctl_trapping(task
);
316 * task_participate_group_stop - participate in a group stop
317 * @task: task participating in a group stop
319 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
320 * Group stop states are cleared and the group stop count is consumed if
321 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
322 * stop, the appropriate %SIGNAL_* flags are set.
325 * Must be called with @task->sighand->siglock held.
328 * %true if group stop completion should be notified to the parent, %false
331 static bool task_participate_group_stop(struct task_struct
*task
)
333 struct signal_struct
*sig
= task
->signal
;
334 bool consume
= task
->jobctl
& JOBCTL_STOP_CONSUME
;
336 WARN_ON_ONCE(!(task
->jobctl
& JOBCTL_STOP_PENDING
));
338 task_clear_jobctl_pending(task
, JOBCTL_STOP_PENDING
);
343 if (!WARN_ON_ONCE(sig
->group_stop_count
== 0))
344 sig
->group_stop_count
--;
347 * Tell the caller to notify completion iff we are entering into a
348 * fresh group stop. Read comment in do_signal_stop() for details.
350 if (!sig
->group_stop_count
&& !(sig
->flags
& SIGNAL_STOP_STOPPED
)) {
351 signal_set_stop_flags(sig
, SIGNAL_STOP_STOPPED
);
358 * allocate a new signal queue record
359 * - this may be called without locks if and only if t == current, otherwise an
360 * appropriate lock must be held to stop the target task from exiting
362 static struct sigqueue
*
363 __sigqueue_alloc(int sig
, struct task_struct
*t
, gfp_t flags
, int override_rlimit
)
365 struct sigqueue
*q
= NULL
;
366 struct user_struct
*user
;
369 * Protect access to @t credentials. This can go away when all
370 * callers hold rcu read lock.
373 user
= get_uid(__task_cred(t
)->user
);
374 atomic_inc(&user
->sigpending
);
377 if (override_rlimit
||
378 atomic_read(&user
->sigpending
) <=
379 task_rlimit(t
, RLIMIT_SIGPENDING
)) {
380 q
= kmem_cache_alloc(sigqueue_cachep
, flags
);
382 print_dropped_signal(sig
);
385 if (unlikely(q
== NULL
)) {
386 atomic_dec(&user
->sigpending
);
389 INIT_LIST_HEAD(&q
->list
);
397 static void __sigqueue_free(struct sigqueue
*q
)
399 if (q
->flags
& SIGQUEUE_PREALLOC
)
401 atomic_dec(&q
->user
->sigpending
);
403 kmem_cache_free(sigqueue_cachep
, q
);
406 void flush_sigqueue(struct sigpending
*queue
)
410 sigemptyset(&queue
->signal
);
411 while (!list_empty(&queue
->list
)) {
412 q
= list_entry(queue
->list
.next
, struct sigqueue
, list
);
413 list_del_init(&q
->list
);
419 * Flush all pending signals for this kthread.
421 void flush_signals(struct task_struct
*t
)
425 spin_lock_irqsave(&t
->sighand
->siglock
, flags
);
426 clear_tsk_thread_flag(t
, TIF_SIGPENDING
);
427 flush_sigqueue(&t
->pending
);
428 flush_sigqueue(&t
->signal
->shared_pending
);
429 spin_unlock_irqrestore(&t
->sighand
->siglock
, flags
);
432 static void __flush_itimer_signals(struct sigpending
*pending
)
434 sigset_t signal
, retain
;
435 struct sigqueue
*q
, *n
;
437 signal
= pending
->signal
;
438 sigemptyset(&retain
);
440 list_for_each_entry_safe(q
, n
, &pending
->list
, list
) {
441 int sig
= q
->info
.si_signo
;
443 if (likely(q
->info
.si_code
!= SI_TIMER
)) {
444 sigaddset(&retain
, sig
);
446 sigdelset(&signal
, sig
);
447 list_del_init(&q
->list
);
452 sigorsets(&pending
->signal
, &signal
, &retain
);
455 void flush_itimer_signals(void)
457 struct task_struct
*tsk
= current
;
460 spin_lock_irqsave(&tsk
->sighand
->siglock
, flags
);
461 __flush_itimer_signals(&tsk
->pending
);
462 __flush_itimer_signals(&tsk
->signal
->shared_pending
);
463 spin_unlock_irqrestore(&tsk
->sighand
->siglock
, flags
);
466 void ignore_signals(struct task_struct
*t
)
470 for (i
= 0; i
< _NSIG
; ++i
)
471 t
->sighand
->action
[i
].sa
.sa_handler
= SIG_IGN
;
477 * Flush all handlers for a task.
481 flush_signal_handlers(struct task_struct
*t
, int force_default
)
484 struct k_sigaction
*ka
= &t
->sighand
->action
[0];
485 for (i
= _NSIG
; i
!= 0 ; i
--) {
486 if (force_default
|| ka
->sa
.sa_handler
!= SIG_IGN
)
487 ka
->sa
.sa_handler
= SIG_DFL
;
489 #ifdef __ARCH_HAS_SA_RESTORER
490 ka
->sa
.sa_restorer
= NULL
;
492 sigemptyset(&ka
->sa
.sa_mask
);
497 int unhandled_signal(struct task_struct
*tsk
, int sig
)
499 void __user
*handler
= tsk
->sighand
->action
[sig
-1].sa
.sa_handler
;
500 if (is_global_init(tsk
))
502 if (handler
!= SIG_IGN
&& handler
!= SIG_DFL
)
504 /* if ptraced, let the tracer determine */
508 static void collect_signal(int sig
, struct sigpending
*list
, siginfo_t
*info
,
511 struct sigqueue
*q
, *first
= NULL
;
514 * Collect the siginfo appropriate to this signal. Check if
515 * there is another siginfo for the same signal.
517 list_for_each_entry(q
, &list
->list
, list
) {
518 if (q
->info
.si_signo
== sig
) {
525 sigdelset(&list
->signal
, sig
);
529 list_del_init(&first
->list
);
530 copy_siginfo(info
, &first
->info
);
533 (first
->flags
& SIGQUEUE_PREALLOC
) &&
534 (info
->si_code
== SI_TIMER
) &&
535 (info
->si_sys_private
);
537 __sigqueue_free(first
);
540 * Ok, it wasn't in the queue. This must be
541 * a fast-pathed signal or we must have been
542 * out of queue space. So zero out the info.
544 info
->si_signo
= sig
;
546 info
->si_code
= SI_USER
;
552 static int __dequeue_signal(struct sigpending
*pending
, sigset_t
*mask
,
553 siginfo_t
*info
, bool *resched_timer
)
555 int sig
= next_signal(pending
, mask
);
558 collect_signal(sig
, pending
, info
, resched_timer
);
563 * Dequeue a signal and return the element to the caller, which is
564 * expected to free it.
566 * All callers have to hold the siglock.
568 int dequeue_signal(struct task_struct
*tsk
, sigset_t
*mask
, siginfo_t
*info
)
570 bool resched_timer
= false;
573 /* We only dequeue private signals from ourselves, we don't let
574 * signalfd steal them
576 signr
= __dequeue_signal(&tsk
->pending
, mask
, info
, &resched_timer
);
578 signr
= __dequeue_signal(&tsk
->signal
->shared_pending
,
579 mask
, info
, &resched_timer
);
583 * itimers are process shared and we restart periodic
584 * itimers in the signal delivery path to prevent DoS
585 * attacks in the high resolution timer case. This is
586 * compliant with the old way of self-restarting
587 * itimers, as the SIGALRM is a legacy signal and only
588 * queued once. Changing the restart behaviour to
589 * restart the timer in the signal dequeue path is
590 * reducing the timer noise on heavy loaded !highres
593 if (unlikely(signr
== SIGALRM
)) {
594 struct hrtimer
*tmr
= &tsk
->signal
->real_timer
;
596 if (!hrtimer_is_queued(tmr
) &&
597 tsk
->signal
->it_real_incr
.tv64
!= 0) {
598 hrtimer_forward(tmr
, tmr
->base
->get_time(),
599 tsk
->signal
->it_real_incr
);
600 hrtimer_restart(tmr
);
609 if (unlikely(sig_kernel_stop(signr
))) {
611 * Set a marker that we have dequeued a stop signal. Our
612 * caller might release the siglock and then the pending
613 * stop signal it is about to process is no longer in the
614 * pending bitmasks, but must still be cleared by a SIGCONT
615 * (and overruled by a SIGKILL). So those cases clear this
616 * shared flag after we've set it. Note that this flag may
617 * remain set after the signal we return is ignored or
618 * handled. That doesn't matter because its only purpose
619 * is to alert stop-signal processing code when another
620 * processor has come along and cleared the flag.
622 current
->jobctl
|= JOBCTL_STOP_DEQUEUED
;
626 * Release the siglock to ensure proper locking order
627 * of timer locks outside of siglocks. Note, we leave
628 * irqs disabled here, since the posix-timers code is
629 * about to disable them again anyway.
631 spin_unlock(&tsk
->sighand
->siglock
);
632 do_schedule_next_timer(info
);
633 spin_lock(&tsk
->sighand
->siglock
);
639 * Tell a process that it has a new active signal..
641 * NOTE! we rely on the previous spin_lock to
642 * lock interrupts for us! We can only be called with
643 * "siglock" held, and the local interrupt must
644 * have been disabled when that got acquired!
646 * No need to set need_resched since signal event passing
647 * goes through ->blocked
649 void signal_wake_up_state(struct task_struct
*t
, unsigned int state
)
651 set_tsk_thread_flag(t
, TIF_SIGPENDING
);
653 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
654 * case. We don't check t->state here because there is a race with it
655 * executing another processor and just now entering stopped state.
656 * By using wake_up_state, we ensure the process will wake up and
657 * handle its death signal.
659 if (!wake_up_state(t
, state
| TASK_INTERRUPTIBLE
))
664 * Remove signals in mask from the pending set and queue.
665 * Returns 1 if any signals were found.
667 * All callers must be holding the siglock.
669 static int flush_sigqueue_mask(sigset_t
*mask
, struct sigpending
*s
)
671 struct sigqueue
*q
, *n
;
674 sigandsets(&m
, mask
, &s
->signal
);
675 if (sigisemptyset(&m
))
678 sigandnsets(&s
->signal
, &s
->signal
, mask
);
679 list_for_each_entry_safe(q
, n
, &s
->list
, list
) {
680 if (sigismember(mask
, q
->info
.si_signo
)) {
681 list_del_init(&q
->list
);
688 static inline int is_si_special(const struct siginfo
*info
)
690 return info
<= SEND_SIG_FORCED
;
693 static inline bool si_fromuser(const struct siginfo
*info
)
695 return info
== SEND_SIG_NOINFO
||
696 (!is_si_special(info
) && SI_FROMUSER(info
));
699 static int dequeue_synchronous_signal(siginfo_t
*info
)
701 struct task_struct
*tsk
= current
;
702 struct sigpending
*pending
= &tsk
->pending
;
703 struct sigqueue
*q
, *sync
= NULL
;
706 * Might a synchronous signal be in the queue?
708 if (!((pending
->signal
.sig
[0] & ~tsk
->blocked
.sig
[0]) & SYNCHRONOUS_MASK
))
712 * Return the first synchronous signal in the queue.
714 list_for_each_entry(q
, &pending
->list
, list
) {
715 /* Synchronous signals have a postive si_code */
716 if ((q
->info
.si_code
> SI_USER
) &&
717 (sigmask(q
->info
.si_signo
) & SYNCHRONOUS_MASK
)) {
725 * Check if there is another siginfo for the same signal.
727 list_for_each_entry_continue(q
, &pending
->list
, list
) {
728 if (q
->info
.si_signo
== sync
->info
.si_signo
)
732 sigdelset(&pending
->signal
, sync
->info
.si_signo
);
735 list_del_init(&sync
->list
);
736 copy_siginfo(info
, &sync
->info
);
737 __sigqueue_free(sync
);
738 return info
->si_signo
;
742 * called with RCU read lock from check_kill_permission()
744 static int kill_ok_by_cred(struct task_struct
*t
)
746 const struct cred
*cred
= current_cred();
747 const struct cred
*tcred
= __task_cred(t
);
749 if (uid_eq(cred
->euid
, tcred
->suid
) ||
750 uid_eq(cred
->euid
, tcred
->uid
) ||
751 uid_eq(cred
->uid
, tcred
->suid
) ||
752 uid_eq(cred
->uid
, tcred
->uid
))
755 if (ns_capable(tcred
->user_ns
, CAP_KILL
))
762 * Bad permissions for sending the signal
763 * - the caller must hold the RCU read lock
765 static int check_kill_permission(int sig
, struct siginfo
*info
,
766 struct task_struct
*t
)
771 if (!valid_signal(sig
))
774 if (!si_fromuser(info
))
777 error
= audit_signal_info(sig
, t
); /* Let audit system see the signal */
781 if (!same_thread_group(current
, t
) &&
782 !kill_ok_by_cred(t
)) {
785 sid
= task_session(t
);
787 * We don't return the error if sid == NULL. The
788 * task was unhashed, the caller must notice this.
790 if (!sid
|| sid
== task_session(current
))
797 return security_task_kill(t
, info
, sig
, 0);
801 * ptrace_trap_notify - schedule trap to notify ptracer
802 * @t: tracee wanting to notify tracer
804 * This function schedules sticky ptrace trap which is cleared on the next
805 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
808 * If @t is running, STOP trap will be taken. If trapped for STOP and
809 * ptracer is listening for events, tracee is woken up so that it can
810 * re-trap for the new event. If trapped otherwise, STOP trap will be
811 * eventually taken without returning to userland after the existing traps
812 * are finished by PTRACE_CONT.
815 * Must be called with @task->sighand->siglock held.
817 static void ptrace_trap_notify(struct task_struct
*t
)
819 WARN_ON_ONCE(!(t
->ptrace
& PT_SEIZED
));
820 assert_spin_locked(&t
->sighand
->siglock
);
822 task_set_jobctl_pending(t
, JOBCTL_TRAP_NOTIFY
);
823 ptrace_signal_wake_up(t
, t
->jobctl
& JOBCTL_LISTENING
);
827 * Handle magic process-wide effects of stop/continue signals. Unlike
828 * the signal actions, these happen immediately at signal-generation
829 * time regardless of blocking, ignoring, or handling. This does the
830 * actual continuing for SIGCONT, but not the actual stopping for stop
831 * signals. The process stop is done as a signal action for SIG_DFL.
833 * Returns true if the signal should be actually delivered, otherwise
834 * it should be dropped.
836 static bool prepare_signal(int sig
, struct task_struct
*p
, bool force
)
838 struct signal_struct
*signal
= p
->signal
;
839 struct task_struct
*t
;
842 if (signal
->flags
& (SIGNAL_GROUP_EXIT
| SIGNAL_GROUP_COREDUMP
)) {
843 if (!(signal
->flags
& SIGNAL_GROUP_EXIT
))
844 return sig
== SIGKILL
;
846 * The process is in the middle of dying, nothing to do.
848 } else if (sig_kernel_stop(sig
)) {
850 * This is a stop signal. Remove SIGCONT from all queues.
852 siginitset(&flush
, sigmask(SIGCONT
));
853 flush_sigqueue_mask(&flush
, &signal
->shared_pending
);
854 for_each_thread(p
, t
)
855 flush_sigqueue_mask(&flush
, &t
->pending
);
856 } else if (sig
== SIGCONT
) {
859 * Remove all stop signals from all queues, wake all threads.
861 siginitset(&flush
, SIG_KERNEL_STOP_MASK
);
862 flush_sigqueue_mask(&flush
, &signal
->shared_pending
);
863 for_each_thread(p
, t
) {
864 flush_sigqueue_mask(&flush
, &t
->pending
);
865 task_clear_jobctl_pending(t
, JOBCTL_STOP_PENDING
);
866 if (likely(!(t
->ptrace
& PT_SEIZED
)))
867 wake_up_state(t
, __TASK_STOPPED
);
869 ptrace_trap_notify(t
);
873 * Notify the parent with CLD_CONTINUED if we were stopped.
875 * If we were in the middle of a group stop, we pretend it
876 * was already finished, and then continued. Since SIGCHLD
877 * doesn't queue we report only CLD_STOPPED, as if the next
878 * CLD_CONTINUED was dropped.
881 if (signal
->flags
& SIGNAL_STOP_STOPPED
)
882 why
|= SIGNAL_CLD_CONTINUED
;
883 else if (signal
->group_stop_count
)
884 why
|= SIGNAL_CLD_STOPPED
;
888 * The first thread which returns from do_signal_stop()
889 * will take ->siglock, notice SIGNAL_CLD_MASK, and
890 * notify its parent. See get_signal_to_deliver().
892 signal_set_stop_flags(signal
, why
| SIGNAL_STOP_CONTINUED
);
893 signal
->group_stop_count
= 0;
894 signal
->group_exit_code
= 0;
898 return !sig_ignored(p
, sig
, force
);
902 * Test if P wants to take SIG. After we've checked all threads with this,
903 * it's equivalent to finding no threads not blocking SIG. Any threads not
904 * blocking SIG were ruled out because they are not running and already
905 * have pending signals. Such threads will dequeue from the shared queue
906 * as soon as they're available, so putting the signal on the shared queue
907 * will be equivalent to sending it to one such thread.
909 static inline int wants_signal(int sig
, struct task_struct
*p
)
911 if (sigismember(&p
->blocked
, sig
))
913 if (p
->flags
& PF_EXITING
)
917 if (task_is_stopped_or_traced(p
))
919 return task_curr(p
) || !signal_pending(p
);
922 static void complete_signal(int sig
, struct task_struct
*p
, int group
)
924 struct signal_struct
*signal
= p
->signal
;
925 struct task_struct
*t
;
928 * Now find a thread we can wake up to take the signal off the queue.
930 * If the main thread wants the signal, it gets first crack.
931 * Probably the least surprising to the average bear.
933 if (wants_signal(sig
, p
))
935 else if (!group
|| thread_group_empty(p
))
937 * There is just one thread and it does not need to be woken.
938 * It will dequeue unblocked signals before it runs again.
943 * Otherwise try to find a suitable thread.
945 t
= signal
->curr_target
;
946 while (!wants_signal(sig
, t
)) {
948 if (t
== signal
->curr_target
)
950 * No thread needs to be woken.
951 * Any eligible threads will see
952 * the signal in the queue soon.
956 signal
->curr_target
= t
;
960 * Found a killable thread. If the signal will be fatal,
961 * then start taking the whole group down immediately.
963 if (sig_fatal(p
, sig
) &&
964 !(signal
->flags
& SIGNAL_GROUP_EXIT
) &&
965 !sigismember(&t
->real_blocked
, sig
) &&
966 (sig
== SIGKILL
|| !p
->ptrace
)) {
968 * This signal will be fatal to the whole group.
970 if (!sig_kernel_coredump(sig
)) {
972 * Start a group exit and wake everybody up.
973 * This way we don't have other threads
974 * running and doing things after a slower
975 * thread has the fatal signal pending.
977 signal
->flags
= SIGNAL_GROUP_EXIT
;
978 signal
->group_exit_code
= sig
;
979 signal
->group_stop_count
= 0;
982 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
983 sigaddset(&t
->pending
.signal
, SIGKILL
);
984 signal_wake_up(t
, 1);
985 } while_each_thread(p
, t
);
991 * The signal is already in the shared-pending queue.
992 * Tell the chosen thread to wake up and dequeue it.
994 signal_wake_up(t
, sig
== SIGKILL
);
998 static inline int legacy_queue(struct sigpending
*signals
, int sig
)
1000 return (sig
< SIGRTMIN
) && sigismember(&signals
->signal
, sig
);
1003 #ifdef CONFIG_USER_NS
1004 static inline void userns_fixup_signal_uid(struct siginfo
*info
, struct task_struct
*t
)
1006 if (current_user_ns() == task_cred_xxx(t
, user_ns
))
1009 if (SI_FROMKERNEL(info
))
1013 info
->si_uid
= from_kuid_munged(task_cred_xxx(t
, user_ns
),
1014 make_kuid(current_user_ns(), info
->si_uid
));
1018 static inline void userns_fixup_signal_uid(struct siginfo
*info
, struct task_struct
*t
)
1024 static int __send_signal(int sig
, struct siginfo
*info
, struct task_struct
*t
,
1025 int group
, int from_ancestor_ns
)
1027 struct sigpending
*pending
;
1029 int override_rlimit
;
1030 int ret
= 0, result
;
1032 assert_spin_locked(&t
->sighand
->siglock
);
1034 result
= TRACE_SIGNAL_IGNORED
;
1035 if (!prepare_signal(sig
, t
,
1036 from_ancestor_ns
|| (info
== SEND_SIG_PRIV
) || (info
== SEND_SIG_FORCED
)))
1039 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
1041 * Short-circuit ignored signals and support queuing
1042 * exactly one non-rt signal, so that we can get more
1043 * detailed information about the cause of the signal.
1045 result
= TRACE_SIGNAL_ALREADY_PENDING
;
1046 if (legacy_queue(pending
, sig
))
1049 result
= TRACE_SIGNAL_DELIVERED
;
1051 * fast-pathed signals for kernel-internal things like SIGSTOP
1054 if (info
== SEND_SIG_FORCED
)
1058 * Real-time signals must be queued if sent by sigqueue, or
1059 * some other real-time mechanism. It is implementation
1060 * defined whether kill() does so. We attempt to do so, on
1061 * the principle of least surprise, but since kill is not
1062 * allowed to fail with EAGAIN when low on memory we just
1063 * make sure at least one signal gets delivered and don't
1064 * pass on the info struct.
1067 override_rlimit
= (is_si_special(info
) || info
->si_code
>= 0);
1069 override_rlimit
= 0;
1071 q
= __sigqueue_alloc(sig
, t
, GFP_ATOMIC
| __GFP_NOTRACK_FALSE_POSITIVE
,
1074 list_add_tail(&q
->list
, &pending
->list
);
1075 switch ((unsigned long) info
) {
1076 case (unsigned long) SEND_SIG_NOINFO
:
1077 q
->info
.si_signo
= sig
;
1078 q
->info
.si_errno
= 0;
1079 q
->info
.si_code
= SI_USER
;
1080 q
->info
.si_pid
= task_tgid_nr_ns(current
,
1081 task_active_pid_ns(t
));
1082 q
->info
.si_uid
= from_kuid_munged(current_user_ns(), current_uid());
1084 case (unsigned long) SEND_SIG_PRIV
:
1085 q
->info
.si_signo
= sig
;
1086 q
->info
.si_errno
= 0;
1087 q
->info
.si_code
= SI_KERNEL
;
1092 copy_siginfo(&q
->info
, info
);
1093 if (from_ancestor_ns
)
1098 userns_fixup_signal_uid(&q
->info
, t
);
1100 } else if (!is_si_special(info
)) {
1101 if (sig
>= SIGRTMIN
&& info
->si_code
!= SI_USER
) {
1103 * Queue overflow, abort. We may abort if the
1104 * signal was rt and sent by user using something
1105 * other than kill().
1107 result
= TRACE_SIGNAL_OVERFLOW_FAIL
;
1112 * This is a silent loss of information. We still
1113 * send the signal, but the *info bits are lost.
1115 result
= TRACE_SIGNAL_LOSE_INFO
;
1120 signalfd_notify(t
, sig
);
1121 sigaddset(&pending
->signal
, sig
);
1122 complete_signal(sig
, t
, group
);
1124 trace_signal_generate(sig
, info
, t
, group
, result
);
1128 static int send_signal(int sig
, struct siginfo
*info
, struct task_struct
*t
,
1131 int from_ancestor_ns
= 0;
1133 #ifdef CONFIG_PID_NS
1134 from_ancestor_ns
= si_fromuser(info
) &&
1135 !task_pid_nr_ns(current
, task_active_pid_ns(t
));
1138 return __send_signal(sig
, info
, t
, group
, from_ancestor_ns
);
1141 static void print_fatal_signal(int signr
)
1143 struct pt_regs
*regs
= signal_pt_regs();
1144 pr_info("potentially unexpected fatal signal %d.\n", signr
);
1146 #if defined(__i386__) && !defined(__arch_um__)
1147 pr_info("code at %08lx: ", regs
->ip
);
1150 for (i
= 0; i
< 16; i
++) {
1153 if (get_user(insn
, (unsigned char *)(regs
->ip
+ i
)))
1155 pr_cont("%02x ", insn
);
1165 static int __init
setup_print_fatal_signals(char *str
)
1167 get_option (&str
, &print_fatal_signals
);
1172 __setup("print-fatal-signals=", setup_print_fatal_signals
);
1175 __group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1177 return send_signal(sig
, info
, p
, 1);
1181 specific_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
1183 return send_signal(sig
, info
, t
, 0);
1186 int do_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
,
1189 unsigned long flags
;
1192 if (lock_task_sighand(p
, &flags
)) {
1193 ret
= send_signal(sig
, info
, p
, group
);
1194 unlock_task_sighand(p
, &flags
);
1201 * Force a signal that the process can't ignore: if necessary
1202 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1204 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1205 * since we do not want to have a signal handler that was blocked
1206 * be invoked when user space had explicitly blocked it.
1208 * We don't want to have recursive SIGSEGV's etc, for example,
1209 * that is why we also clear SIGNAL_UNKILLABLE.
1212 force_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*t
)
1214 unsigned long int flags
;
1215 int ret
, blocked
, ignored
;
1216 struct k_sigaction
*action
;
1218 spin_lock_irqsave(&t
->sighand
->siglock
, flags
);
1219 action
= &t
->sighand
->action
[sig
-1];
1220 ignored
= action
->sa
.sa_handler
== SIG_IGN
;
1221 blocked
= sigismember(&t
->blocked
, sig
);
1222 if (blocked
|| ignored
) {
1223 action
->sa
.sa_handler
= SIG_DFL
;
1225 sigdelset(&t
->blocked
, sig
);
1226 recalc_sigpending_and_wake(t
);
1229 if (action
->sa
.sa_handler
== SIG_DFL
)
1230 t
->signal
->flags
&= ~SIGNAL_UNKILLABLE
;
1231 ret
= specific_send_sig_info(sig
, info
, t
);
1232 spin_unlock_irqrestore(&t
->sighand
->siglock
, flags
);
1238 * Nuke all other threads in the group.
1240 int zap_other_threads(struct task_struct
*p
)
1242 struct task_struct
*t
= p
;
1245 p
->signal
->group_stop_count
= 0;
1247 while_each_thread(p
, t
) {
1248 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
1251 /* Don't bother with already dead threads */
1254 sigaddset(&t
->pending
.signal
, SIGKILL
);
1255 signal_wake_up(t
, 1);
1261 struct sighand_struct
*__lock_task_sighand(struct task_struct
*tsk
,
1262 unsigned long *flags
)
1264 struct sighand_struct
*sighand
;
1268 * Disable interrupts early to avoid deadlocks.
1269 * See rcu_read_unlock() comment header for details.
1271 local_irq_save(*flags
);
1273 sighand
= rcu_dereference(tsk
->sighand
);
1274 if (unlikely(sighand
== NULL
)) {
1276 local_irq_restore(*flags
);
1280 * This sighand can be already freed and even reused, but
1281 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1282 * initializes ->siglock: this slab can't go away, it has
1283 * the same object type, ->siglock can't be reinitialized.
1285 * We need to ensure that tsk->sighand is still the same
1286 * after we take the lock, we can race with de_thread() or
1287 * __exit_signal(). In the latter case the next iteration
1288 * must see ->sighand == NULL.
1290 spin_lock(&sighand
->siglock
);
1291 if (likely(sighand
== tsk
->sighand
)) {
1295 spin_unlock(&sighand
->siglock
);
1297 local_irq_restore(*flags
);
1304 * send signal info to all the members of a group
1306 int group_send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1311 ret
= check_kill_permission(sig
, info
, p
);
1315 ret
= do_send_sig_info(sig
, info
, p
, true);
1321 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1322 * control characters do (^C, ^Z etc)
1323 * - the caller must hold at least a readlock on tasklist_lock
1325 int __kill_pgrp_info(int sig
, struct siginfo
*info
, struct pid
*pgrp
)
1327 struct task_struct
*p
= NULL
;
1328 int retval
, success
;
1332 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
1333 int err
= group_send_sig_info(sig
, info
, p
);
1336 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
1337 return success
? 0 : retval
;
1340 int kill_pid_info(int sig
, struct siginfo
*info
, struct pid
*pid
)
1343 struct task_struct
*p
;
1347 p
= pid_task(pid
, PIDTYPE_PID
);
1349 error
= group_send_sig_info(sig
, info
, p
);
1351 if (likely(!p
|| error
!= -ESRCH
))
1355 * The task was unhashed in between, try again. If it
1356 * is dead, pid_task() will return NULL, if we race with
1357 * de_thread() it will find the new leader.
1362 int kill_proc_info(int sig
, struct siginfo
*info
, pid_t pid
)
1366 error
= kill_pid_info(sig
, info
, find_vpid(pid
));
1371 static int kill_as_cred_perm(const struct cred
*cred
,
1372 struct task_struct
*target
)
1374 const struct cred
*pcred
= __task_cred(target
);
1375 if (!uid_eq(cred
->euid
, pcred
->suid
) && !uid_eq(cred
->euid
, pcred
->uid
) &&
1376 !uid_eq(cred
->uid
, pcred
->suid
) && !uid_eq(cred
->uid
, pcred
->uid
))
1381 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1382 int kill_pid_info_as_cred(int sig
, struct siginfo
*info
, struct pid
*pid
,
1383 const struct cred
*cred
, u32 secid
)
1386 struct task_struct
*p
;
1387 unsigned long flags
;
1389 if (!valid_signal(sig
))
1393 p
= pid_task(pid
, PIDTYPE_PID
);
1398 if (si_fromuser(info
) && !kill_as_cred_perm(cred
, p
)) {
1402 ret
= security_task_kill(p
, info
, sig
, secid
);
1407 if (lock_task_sighand(p
, &flags
)) {
1408 ret
= __send_signal(sig
, info
, p
, 1, 0);
1409 unlock_task_sighand(p
, &flags
);
1417 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred
);
1420 * kill_something_info() interprets pid in interesting ways just like kill(2).
1422 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1423 * is probably wrong. Should make it like BSD or SYSV.
1426 static int kill_something_info(int sig
, struct siginfo
*info
, pid_t pid
)
1432 ret
= kill_pid_info(sig
, info
, find_vpid(pid
));
1437 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1441 read_lock(&tasklist_lock
);
1443 ret
= __kill_pgrp_info(sig
, info
,
1444 pid
? find_vpid(-pid
) : task_pgrp(current
));
1446 int retval
= 0, count
= 0;
1447 struct task_struct
* p
;
1449 for_each_process(p
) {
1450 if (task_pid_vnr(p
) > 1 &&
1451 !same_thread_group(p
, current
)) {
1452 int err
= group_send_sig_info(sig
, info
, p
);
1458 ret
= count
? retval
: -ESRCH
;
1460 read_unlock(&tasklist_lock
);
1466 * These are for backward compatibility with the rest of the kernel source.
1469 int send_sig_info(int sig
, struct siginfo
*info
, struct task_struct
*p
)
1472 * Make sure legacy kernel users don't send in bad values
1473 * (normal paths check this in check_kill_permission).
1475 if (!valid_signal(sig
))
1478 return do_send_sig_info(sig
, info
, p
, false);
1481 #define __si_special(priv) \
1482 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1485 send_sig(int sig
, struct task_struct
*p
, int priv
)
1487 return send_sig_info(sig
, __si_special(priv
), p
);
1491 force_sig(int sig
, struct task_struct
*p
)
1493 force_sig_info(sig
, SEND_SIG_PRIV
, p
);
1497 * When things go south during signal handling, we
1498 * will force a SIGSEGV. And if the signal that caused
1499 * the problem was already a SIGSEGV, we'll want to
1500 * make sure we don't even try to deliver the signal..
1503 force_sigsegv(int sig
, struct task_struct
*p
)
1505 if (sig
== SIGSEGV
) {
1506 unsigned long flags
;
1507 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
1508 p
->sighand
->action
[sig
- 1].sa
.sa_handler
= SIG_DFL
;
1509 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
1511 force_sig(SIGSEGV
, p
);
1515 int kill_pgrp(struct pid
*pid
, int sig
, int priv
)
1519 read_lock(&tasklist_lock
);
1520 ret
= __kill_pgrp_info(sig
, __si_special(priv
), pid
);
1521 read_unlock(&tasklist_lock
);
1525 EXPORT_SYMBOL(kill_pgrp
);
1527 int kill_pid(struct pid
*pid
, int sig
, int priv
)
1529 return kill_pid_info(sig
, __si_special(priv
), pid
);
1531 EXPORT_SYMBOL(kill_pid
);
1534 * These functions support sending signals using preallocated sigqueue
1535 * structures. This is needed "because realtime applications cannot
1536 * afford to lose notifications of asynchronous events, like timer
1537 * expirations or I/O completions". In the case of POSIX Timers
1538 * we allocate the sigqueue structure from the timer_create. If this
1539 * allocation fails we are able to report the failure to the application
1540 * with an EAGAIN error.
1542 struct sigqueue
*sigqueue_alloc(void)
1544 struct sigqueue
*q
= __sigqueue_alloc(-1, current
, GFP_KERNEL
, 0);
1547 q
->flags
|= SIGQUEUE_PREALLOC
;
1552 void sigqueue_free(struct sigqueue
*q
)
1554 unsigned long flags
;
1555 spinlock_t
*lock
= ¤t
->sighand
->siglock
;
1557 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1559 * We must hold ->siglock while testing q->list
1560 * to serialize with collect_signal() or with
1561 * __exit_signal()->flush_sigqueue().
1563 spin_lock_irqsave(lock
, flags
);
1564 q
->flags
&= ~SIGQUEUE_PREALLOC
;
1566 * If it is queued it will be freed when dequeued,
1567 * like the "regular" sigqueue.
1569 if (!list_empty(&q
->list
))
1571 spin_unlock_irqrestore(lock
, flags
);
1577 int send_sigqueue(struct sigqueue
*q
, struct task_struct
*t
, int group
)
1579 int sig
= q
->info
.si_signo
;
1580 struct sigpending
*pending
;
1581 unsigned long flags
;
1584 BUG_ON(!(q
->flags
& SIGQUEUE_PREALLOC
));
1587 if (!likely(lock_task_sighand(t
, &flags
)))
1590 ret
= 1; /* the signal is ignored */
1591 result
= TRACE_SIGNAL_IGNORED
;
1592 if (!prepare_signal(sig
, t
, false))
1596 if (unlikely(!list_empty(&q
->list
))) {
1598 * If an SI_TIMER entry is already queue just increment
1599 * the overrun count.
1601 BUG_ON(q
->info
.si_code
!= SI_TIMER
);
1602 q
->info
.si_overrun
++;
1603 result
= TRACE_SIGNAL_ALREADY_PENDING
;
1606 q
->info
.si_overrun
= 0;
1608 signalfd_notify(t
, sig
);
1609 pending
= group
? &t
->signal
->shared_pending
: &t
->pending
;
1610 list_add_tail(&q
->list
, &pending
->list
);
1611 sigaddset(&pending
->signal
, sig
);
1612 complete_signal(sig
, t
, group
);
1613 result
= TRACE_SIGNAL_DELIVERED
;
1615 trace_signal_generate(sig
, &q
->info
, t
, group
, result
);
1616 unlock_task_sighand(t
, &flags
);
1622 * Let a parent know about the death of a child.
1623 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1625 * Returns true if our parent ignored us and so we've switched to
1628 bool do_notify_parent(struct task_struct
*tsk
, int sig
)
1630 struct siginfo info
;
1631 unsigned long flags
;
1632 struct sighand_struct
*psig
;
1633 bool autoreap
= false;
1634 cputime_t utime
, stime
;
1638 /* do_notify_parent_cldstop should have been called instead. */
1639 BUG_ON(task_is_stopped_or_traced(tsk
));
1641 BUG_ON(!tsk
->ptrace
&&
1642 (tsk
->group_leader
!= tsk
|| !thread_group_empty(tsk
)));
1644 if (sig
!= SIGCHLD
) {
1646 * This is only possible if parent == real_parent.
1647 * Check if it has changed security domain.
1649 if (tsk
->parent_exec_id
!= tsk
->parent
->self_exec_id
)
1653 info
.si_signo
= sig
;
1656 * We are under tasklist_lock here so our parent is tied to
1657 * us and cannot change.
1659 * task_active_pid_ns will always return the same pid namespace
1660 * until a task passes through release_task.
1662 * write_lock() currently calls preempt_disable() which is the
1663 * same as rcu_read_lock(), but according to Oleg, this is not
1664 * correct to rely on this
1667 info
.si_pid
= task_pid_nr_ns(tsk
, task_active_pid_ns(tsk
->parent
));
1668 info
.si_uid
= from_kuid_munged(task_cred_xxx(tsk
->parent
, user_ns
),
1672 task_cputime(tsk
, &utime
, &stime
);
1673 info
.si_utime
= cputime_to_clock_t(utime
+ tsk
->signal
->utime
);
1674 info
.si_stime
= cputime_to_clock_t(stime
+ tsk
->signal
->stime
);
1676 info
.si_status
= tsk
->exit_code
& 0x7f;
1677 if (tsk
->exit_code
& 0x80)
1678 info
.si_code
= CLD_DUMPED
;
1679 else if (tsk
->exit_code
& 0x7f)
1680 info
.si_code
= CLD_KILLED
;
1682 info
.si_code
= CLD_EXITED
;
1683 info
.si_status
= tsk
->exit_code
>> 8;
1686 psig
= tsk
->parent
->sighand
;
1687 spin_lock_irqsave(&psig
->siglock
, flags
);
1688 if (!tsk
->ptrace
&& sig
== SIGCHLD
&&
1689 (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
||
1690 (psig
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDWAIT
))) {
1692 * We are exiting and our parent doesn't care. POSIX.1
1693 * defines special semantics for setting SIGCHLD to SIG_IGN
1694 * or setting the SA_NOCLDWAIT flag: we should be reaped
1695 * automatically and not left for our parent's wait4 call.
1696 * Rather than having the parent do it as a magic kind of
1697 * signal handler, we just set this to tell do_exit that we
1698 * can be cleaned up without becoming a zombie. Note that
1699 * we still call __wake_up_parent in this case, because a
1700 * blocked sys_wait4 might now return -ECHILD.
1702 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1703 * is implementation-defined: we do (if you don't want
1704 * it, just use SIG_IGN instead).
1707 if (psig
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
)
1710 if (valid_signal(sig
) && sig
)
1711 __group_send_sig_info(sig
, &info
, tsk
->parent
);
1712 __wake_up_parent(tsk
, tsk
->parent
);
1713 spin_unlock_irqrestore(&psig
->siglock
, flags
);
1719 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1720 * @tsk: task reporting the state change
1721 * @for_ptracer: the notification is for ptracer
1722 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1724 * Notify @tsk's parent that the stopped/continued state has changed. If
1725 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1726 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1729 * Must be called with tasklist_lock at least read locked.
1731 static void do_notify_parent_cldstop(struct task_struct
*tsk
,
1732 bool for_ptracer
, int why
)
1734 struct siginfo info
;
1735 unsigned long flags
;
1736 struct task_struct
*parent
;
1737 struct sighand_struct
*sighand
;
1738 cputime_t utime
, stime
;
1741 parent
= tsk
->parent
;
1743 tsk
= tsk
->group_leader
;
1744 parent
= tsk
->real_parent
;
1747 info
.si_signo
= SIGCHLD
;
1750 * see comment in do_notify_parent() about the following 4 lines
1753 info
.si_pid
= task_pid_nr_ns(tsk
, task_active_pid_ns(parent
));
1754 info
.si_uid
= from_kuid_munged(task_cred_xxx(parent
, user_ns
), task_uid(tsk
));
1757 task_cputime(tsk
, &utime
, &stime
);
1758 info
.si_utime
= cputime_to_clock_t(utime
);
1759 info
.si_stime
= cputime_to_clock_t(stime
);
1764 info
.si_status
= SIGCONT
;
1767 info
.si_status
= tsk
->signal
->group_exit_code
& 0x7f;
1770 info
.si_status
= tsk
->exit_code
& 0x7f;
1776 sighand
= parent
->sighand
;
1777 spin_lock_irqsave(&sighand
->siglock
, flags
);
1778 if (sighand
->action
[SIGCHLD
-1].sa
.sa_handler
!= SIG_IGN
&&
1779 !(sighand
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDSTOP
))
1780 __group_send_sig_info(SIGCHLD
, &info
, parent
);
1782 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1784 __wake_up_parent(tsk
, parent
);
1785 spin_unlock_irqrestore(&sighand
->siglock
, flags
);
1788 static inline int may_ptrace_stop(void)
1790 if (!likely(current
->ptrace
))
1793 * Are we in the middle of do_coredump?
1794 * If so and our tracer is also part of the coredump stopping
1795 * is a deadlock situation, and pointless because our tracer
1796 * is dead so don't allow us to stop.
1797 * If SIGKILL was already sent before the caller unlocked
1798 * ->siglock we must see ->core_state != NULL. Otherwise it
1799 * is safe to enter schedule().
1801 * This is almost outdated, a task with the pending SIGKILL can't
1802 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1803 * after SIGKILL was already dequeued.
1805 if (unlikely(current
->mm
->core_state
) &&
1806 unlikely(current
->mm
== current
->parent
->mm
))
1813 * Return non-zero if there is a SIGKILL that should be waking us up.
1814 * Called with the siglock held.
1816 static int sigkill_pending(struct task_struct
*tsk
)
1818 return sigismember(&tsk
->pending
.signal
, SIGKILL
) ||
1819 sigismember(&tsk
->signal
->shared_pending
.signal
, SIGKILL
);
1823 * This must be called with current->sighand->siglock held.
1825 * This should be the path for all ptrace stops.
1826 * We always set current->last_siginfo while stopped here.
1827 * That makes it a way to test a stopped process for
1828 * being ptrace-stopped vs being job-control-stopped.
1830 * If we actually decide not to stop at all because the tracer
1831 * is gone, we keep current->exit_code unless clear_code.
1833 static void ptrace_stop(int exit_code
, int why
, int clear_code
, siginfo_t
*info
)
1834 __releases(¤t
->sighand
->siglock
)
1835 __acquires(¤t
->sighand
->siglock
)
1837 bool gstop_done
= false;
1839 if (arch_ptrace_stop_needed(exit_code
, info
)) {
1841 * The arch code has something special to do before a
1842 * ptrace stop. This is allowed to block, e.g. for faults
1843 * on user stack pages. We can't keep the siglock while
1844 * calling arch_ptrace_stop, so we must release it now.
1845 * To preserve proper semantics, we must do this before
1846 * any signal bookkeeping like checking group_stop_count.
1847 * Meanwhile, a SIGKILL could come in before we retake the
1848 * siglock. That must prevent us from sleeping in TASK_TRACED.
1849 * So after regaining the lock, we must check for SIGKILL.
1851 spin_unlock_irq(¤t
->sighand
->siglock
);
1852 arch_ptrace_stop(exit_code
, info
);
1853 spin_lock_irq(¤t
->sighand
->siglock
);
1854 if (sigkill_pending(current
))
1859 * We're committing to trapping. TRACED should be visible before
1860 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1861 * Also, transition to TRACED and updates to ->jobctl should be
1862 * atomic with respect to siglock and should be done after the arch
1863 * hook as siglock is released and regrabbed across it.
1865 set_current_state(TASK_TRACED
);
1867 current
->last_siginfo
= info
;
1868 current
->exit_code
= exit_code
;
1871 * If @why is CLD_STOPPED, we're trapping to participate in a group
1872 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1873 * across siglock relocks since INTERRUPT was scheduled, PENDING
1874 * could be clear now. We act as if SIGCONT is received after
1875 * TASK_TRACED is entered - ignore it.
1877 if (why
== CLD_STOPPED
&& (current
->jobctl
& JOBCTL_STOP_PENDING
))
1878 gstop_done
= task_participate_group_stop(current
);
1880 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1881 task_clear_jobctl_pending(current
, JOBCTL_TRAP_STOP
);
1882 if (info
&& info
->si_code
>> 8 == PTRACE_EVENT_STOP
)
1883 task_clear_jobctl_pending(current
, JOBCTL_TRAP_NOTIFY
);
1885 /* entering a trap, clear TRAPPING */
1886 task_clear_jobctl_trapping(current
);
1888 spin_unlock_irq(¤t
->sighand
->siglock
);
1889 read_lock(&tasklist_lock
);
1890 if (may_ptrace_stop()) {
1892 * Notify parents of the stop.
1894 * While ptraced, there are two parents - the ptracer and
1895 * the real_parent of the group_leader. The ptracer should
1896 * know about every stop while the real parent is only
1897 * interested in the completion of group stop. The states
1898 * for the two don't interact with each other. Notify
1899 * separately unless they're gonna be duplicates.
1901 do_notify_parent_cldstop(current
, true, why
);
1902 if (gstop_done
&& ptrace_reparented(current
))
1903 do_notify_parent_cldstop(current
, false, why
);
1906 * Don't want to allow preemption here, because
1907 * sys_ptrace() needs this task to be inactive.
1909 * XXX: implement read_unlock_no_resched().
1912 read_unlock(&tasklist_lock
);
1913 preempt_enable_no_resched();
1914 freezable_schedule();
1917 * By the time we got the lock, our tracer went away.
1918 * Don't drop the lock yet, another tracer may come.
1920 * If @gstop_done, the ptracer went away between group stop
1921 * completion and here. During detach, it would have set
1922 * JOBCTL_STOP_PENDING on us and we'll re-enter
1923 * TASK_STOPPED in do_signal_stop() on return, so notifying
1924 * the real parent of the group stop completion is enough.
1927 do_notify_parent_cldstop(current
, false, why
);
1929 /* tasklist protects us from ptrace_freeze_traced() */
1930 __set_current_state(TASK_RUNNING
);
1932 current
->exit_code
= 0;
1933 read_unlock(&tasklist_lock
);
1937 * We are back. Now reacquire the siglock before touching
1938 * last_siginfo, so that we are sure to have synchronized with
1939 * any signal-sending on another CPU that wants to examine it.
1941 spin_lock_irq(¤t
->sighand
->siglock
);
1942 current
->last_siginfo
= NULL
;
1944 /* LISTENING can be set only during STOP traps, clear it */
1945 current
->jobctl
&= ~JOBCTL_LISTENING
;
1948 * Queued signals ignored us while we were stopped for tracing.
1949 * So check for any that we should take before resuming user mode.
1950 * This sets TIF_SIGPENDING, but never clears it.
1952 recalc_sigpending_tsk(current
);
1955 static void ptrace_do_notify(int signr
, int exit_code
, int why
)
1959 memset(&info
, 0, sizeof info
);
1960 info
.si_signo
= signr
;
1961 info
.si_code
= exit_code
;
1962 info
.si_pid
= task_pid_vnr(current
);
1963 info
.si_uid
= from_kuid_munged(current_user_ns(), current_uid());
1965 /* Let the debugger run. */
1966 ptrace_stop(exit_code
, why
, 1, &info
);
1969 void ptrace_notify(int exit_code
)
1971 BUG_ON((exit_code
& (0x7f | ~0xffff)) != SIGTRAP
);
1972 if (unlikely(current
->task_works
))
1975 spin_lock_irq(¤t
->sighand
->siglock
);
1976 ptrace_do_notify(SIGTRAP
, exit_code
, CLD_TRAPPED
);
1977 spin_unlock_irq(¤t
->sighand
->siglock
);
1981 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1982 * @signr: signr causing group stop if initiating
1984 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1985 * and participate in it. If already set, participate in the existing
1986 * group stop. If participated in a group stop (and thus slept), %true is
1987 * returned with siglock released.
1989 * If ptraced, this function doesn't handle stop itself. Instead,
1990 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1991 * untouched. The caller must ensure that INTERRUPT trap handling takes
1992 * places afterwards.
1995 * Must be called with @current->sighand->siglock held, which is released
1999 * %false if group stop is already cancelled or ptrace trap is scheduled.
2000 * %true if participated in group stop.
2002 static bool do_signal_stop(int signr
)
2003 __releases(¤t
->sighand
->siglock
)
2005 struct signal_struct
*sig
= current
->signal
;
2007 if (!(current
->jobctl
& JOBCTL_STOP_PENDING
)) {
2008 unsigned long gstop
= JOBCTL_STOP_PENDING
| JOBCTL_STOP_CONSUME
;
2009 struct task_struct
*t
;
2011 /* signr will be recorded in task->jobctl for retries */
2012 WARN_ON_ONCE(signr
& ~JOBCTL_STOP_SIGMASK
);
2014 if (!likely(current
->jobctl
& JOBCTL_STOP_DEQUEUED
) ||
2015 unlikely(signal_group_exit(sig
)))
2018 * There is no group stop already in progress. We must
2021 * While ptraced, a task may be resumed while group stop is
2022 * still in effect and then receive a stop signal and
2023 * initiate another group stop. This deviates from the
2024 * usual behavior as two consecutive stop signals can't
2025 * cause two group stops when !ptraced. That is why we
2026 * also check !task_is_stopped(t) below.
2028 * The condition can be distinguished by testing whether
2029 * SIGNAL_STOP_STOPPED is already set. Don't generate
2030 * group_exit_code in such case.
2032 * This is not necessary for SIGNAL_STOP_CONTINUED because
2033 * an intervening stop signal is required to cause two
2034 * continued events regardless of ptrace.
2036 if (!(sig
->flags
& SIGNAL_STOP_STOPPED
))
2037 sig
->group_exit_code
= signr
;
2039 sig
->group_stop_count
= 0;
2041 if (task_set_jobctl_pending(current
, signr
| gstop
))
2042 sig
->group_stop_count
++;
2045 while_each_thread(current
, t
) {
2047 * Setting state to TASK_STOPPED for a group
2048 * stop is always done with the siglock held,
2049 * so this check has no races.
2051 if (!task_is_stopped(t
) &&
2052 task_set_jobctl_pending(t
, signr
| gstop
)) {
2053 sig
->group_stop_count
++;
2054 if (likely(!(t
->ptrace
& PT_SEIZED
)))
2055 signal_wake_up(t
, 0);
2057 ptrace_trap_notify(t
);
2062 if (likely(!current
->ptrace
)) {
2066 * If there are no other threads in the group, or if there
2067 * is a group stop in progress and we are the last to stop,
2068 * report to the parent.
2070 if (task_participate_group_stop(current
))
2071 notify
= CLD_STOPPED
;
2073 __set_current_state(TASK_STOPPED
);
2074 spin_unlock_irq(¤t
->sighand
->siglock
);
2077 * Notify the parent of the group stop completion. Because
2078 * we're not holding either the siglock or tasklist_lock
2079 * here, ptracer may attach inbetween; however, this is for
2080 * group stop and should always be delivered to the real
2081 * parent of the group leader. The new ptracer will get
2082 * its notification when this task transitions into
2086 read_lock(&tasklist_lock
);
2087 do_notify_parent_cldstop(current
, false, notify
);
2088 read_unlock(&tasklist_lock
);
2091 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2092 freezable_schedule();
2096 * While ptraced, group stop is handled by STOP trap.
2097 * Schedule it and let the caller deal with it.
2099 task_set_jobctl_pending(current
, JOBCTL_TRAP_STOP
);
2105 * do_jobctl_trap - take care of ptrace jobctl traps
2107 * When PT_SEIZED, it's used for both group stop and explicit
2108 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2109 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2110 * the stop signal; otherwise, %SIGTRAP.
2112 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2113 * number as exit_code and no siginfo.
2116 * Must be called with @current->sighand->siglock held, which may be
2117 * released and re-acquired before returning with intervening sleep.
2119 static void do_jobctl_trap(void)
2121 struct signal_struct
*signal
= current
->signal
;
2122 int signr
= current
->jobctl
& JOBCTL_STOP_SIGMASK
;
2124 if (current
->ptrace
& PT_SEIZED
) {
2125 if (!signal
->group_stop_count
&&
2126 !(signal
->flags
& SIGNAL_STOP_STOPPED
))
2128 WARN_ON_ONCE(!signr
);
2129 ptrace_do_notify(signr
, signr
| (PTRACE_EVENT_STOP
<< 8),
2132 WARN_ON_ONCE(!signr
);
2133 ptrace_stop(signr
, CLD_STOPPED
, 0, NULL
);
2134 current
->exit_code
= 0;
2138 static int ptrace_signal(int signr
, siginfo_t
*info
)
2140 ptrace_signal_deliver();
2142 * We do not check sig_kernel_stop(signr) but set this marker
2143 * unconditionally because we do not know whether debugger will
2144 * change signr. This flag has no meaning unless we are going
2145 * to stop after return from ptrace_stop(). In this case it will
2146 * be checked in do_signal_stop(), we should only stop if it was
2147 * not cleared by SIGCONT while we were sleeping. See also the
2148 * comment in dequeue_signal().
2150 current
->jobctl
|= JOBCTL_STOP_DEQUEUED
;
2151 ptrace_stop(signr
, CLD_TRAPPED
, 0, info
);
2153 /* We're back. Did the debugger cancel the sig? */
2154 signr
= current
->exit_code
;
2158 current
->exit_code
= 0;
2161 * Update the siginfo structure if the signal has
2162 * changed. If the debugger wanted something
2163 * specific in the siginfo structure then it should
2164 * have updated *info via PTRACE_SETSIGINFO.
2166 if (signr
!= info
->si_signo
) {
2167 info
->si_signo
= signr
;
2169 info
->si_code
= SI_USER
;
2171 info
->si_pid
= task_pid_vnr(current
->parent
);
2172 info
->si_uid
= from_kuid_munged(current_user_ns(),
2173 task_uid(current
->parent
));
2177 /* If the (new) signal is now blocked, requeue it. */
2178 if (sigismember(¤t
->blocked
, signr
)) {
2179 specific_send_sig_info(signr
, info
, current
);
2186 int get_signal(struct ksignal
*ksig
)
2188 struct sighand_struct
*sighand
= current
->sighand
;
2189 struct signal_struct
*signal
= current
->signal
;
2192 if (unlikely(current
->task_works
))
2195 if (unlikely(uprobe_deny_signal()))
2199 * Do this once, we can't return to user-mode if freezing() == T.
2200 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2201 * thus do not need another check after return.
2206 spin_lock_irq(&sighand
->siglock
);
2208 * Every stopped thread goes here after wakeup. Check to see if
2209 * we should notify the parent, prepare_signal(SIGCONT) encodes
2210 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2212 if (unlikely(signal
->flags
& SIGNAL_CLD_MASK
)) {
2215 if (signal
->flags
& SIGNAL_CLD_CONTINUED
)
2216 why
= CLD_CONTINUED
;
2220 signal
->flags
&= ~SIGNAL_CLD_MASK
;
2222 spin_unlock_irq(&sighand
->siglock
);
2225 * Notify the parent that we're continuing. This event is
2226 * always per-process and doesn't make whole lot of sense
2227 * for ptracers, who shouldn't consume the state via
2228 * wait(2) either, but, for backward compatibility, notify
2229 * the ptracer of the group leader too unless it's gonna be
2232 read_lock(&tasklist_lock
);
2233 do_notify_parent_cldstop(current
, false, why
);
2235 if (ptrace_reparented(current
->group_leader
))
2236 do_notify_parent_cldstop(current
->group_leader
,
2238 read_unlock(&tasklist_lock
);
2243 /* Has this task already been marked for death? */
2244 ksig
->info
.si_signo
= signr
= SIGKILL
;
2245 if (signal_group_exit(signal
))
2249 struct k_sigaction
*ka
;
2251 if (unlikely(current
->jobctl
& JOBCTL_STOP_PENDING
) &&
2255 if (unlikely(current
->jobctl
& JOBCTL_TRAP_MASK
)) {
2257 spin_unlock_irq(&sighand
->siglock
);
2262 * Signals generated by the execution of an instruction
2263 * need to be delivered before any other pending signals
2264 * so that the instruction pointer in the signal stack
2265 * frame points to the faulting instruction.
2267 signr
= dequeue_synchronous_signal(&ksig
->info
);
2269 signr
= dequeue_signal(current
, ¤t
->blocked
, &ksig
->info
);
2272 break; /* will return 0 */
2274 if (unlikely(current
->ptrace
) && signr
!= SIGKILL
) {
2275 signr
= ptrace_signal(signr
, &ksig
->info
);
2280 ka
= &sighand
->action
[signr
-1];
2282 /* Trace actually delivered signals. */
2283 trace_signal_deliver(signr
, &ksig
->info
, ka
);
2285 if (ka
->sa
.sa_handler
== SIG_IGN
) /* Do nothing. */
2287 if (ka
->sa
.sa_handler
!= SIG_DFL
) {
2288 /* Run the handler. */
2291 if (ka
->sa
.sa_flags
& SA_ONESHOT
)
2292 ka
->sa
.sa_handler
= SIG_DFL
;
2294 break; /* will return non-zero "signr" value */
2298 * Now we are doing the default action for this signal.
2300 if (sig_kernel_ignore(signr
)) /* Default is nothing. */
2304 * Global init gets no signals it doesn't want.
2305 * Container-init gets no signals it doesn't want from same
2308 * Note that if global/container-init sees a sig_kernel_only()
2309 * signal here, the signal must have been generated internally
2310 * or must have come from an ancestor namespace. In either
2311 * case, the signal cannot be dropped.
2313 if (unlikely(signal
->flags
& SIGNAL_UNKILLABLE
) &&
2314 !sig_kernel_only(signr
))
2317 if (sig_kernel_stop(signr
)) {
2319 * The default action is to stop all threads in
2320 * the thread group. The job control signals
2321 * do nothing in an orphaned pgrp, but SIGSTOP
2322 * always works. Note that siglock needs to be
2323 * dropped during the call to is_orphaned_pgrp()
2324 * because of lock ordering with tasklist_lock.
2325 * This allows an intervening SIGCONT to be posted.
2326 * We need to check for that and bail out if necessary.
2328 if (signr
!= SIGSTOP
) {
2329 spin_unlock_irq(&sighand
->siglock
);
2331 /* signals can be posted during this window */
2333 if (is_current_pgrp_orphaned())
2336 spin_lock_irq(&sighand
->siglock
);
2339 if (likely(do_signal_stop(ksig
->info
.si_signo
))) {
2340 /* It released the siglock. */
2345 * We didn't actually stop, due to a race
2346 * with SIGCONT or something like that.
2352 spin_unlock_irq(&sighand
->siglock
);
2355 * Anything else is fatal, maybe with a core dump.
2357 current
->flags
|= PF_SIGNALED
;
2359 if (sig_kernel_coredump(signr
)) {
2360 if (print_fatal_signals
)
2361 print_fatal_signal(ksig
->info
.si_signo
);
2362 proc_coredump_connector(current
);
2364 * If it was able to dump core, this kills all
2365 * other threads in the group and synchronizes with
2366 * their demise. If we lost the race with another
2367 * thread getting here, it set group_exit_code
2368 * first and our do_group_exit call below will use
2369 * that value and ignore the one we pass it.
2371 do_coredump(&ksig
->info
);
2375 * Death signals, no core dump.
2377 do_group_exit(ksig
->info
.si_signo
);
2380 spin_unlock_irq(&sighand
->siglock
);
2383 return ksig
->sig
> 0;
2387 * signal_delivered -
2388 * @ksig: kernel signal struct
2389 * @stepping: nonzero if debugger single-step or block-step in use
2391 * This function should be called when a signal has successfully been
2392 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2393 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2394 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2396 static void signal_delivered(struct ksignal
*ksig
, int stepping
)
2400 /* A signal was successfully delivered, and the
2401 saved sigmask was stored on the signal frame,
2402 and will be restored by sigreturn. So we can
2403 simply clear the restore sigmask flag. */
2404 clear_restore_sigmask();
2406 sigorsets(&blocked
, ¤t
->blocked
, &ksig
->ka
.sa
.sa_mask
);
2407 if (!(ksig
->ka
.sa
.sa_flags
& SA_NODEFER
))
2408 sigaddset(&blocked
, ksig
->sig
);
2409 set_current_blocked(&blocked
);
2410 tracehook_signal_handler(stepping
);
2413 void signal_setup_done(int failed
, struct ksignal
*ksig
, int stepping
)
2416 force_sigsegv(ksig
->sig
, current
);
2418 signal_delivered(ksig
, stepping
);
2422 * It could be that complete_signal() picked us to notify about the
2423 * group-wide signal. Other threads should be notified now to take
2424 * the shared signals in @which since we will not.
2426 static void retarget_shared_pending(struct task_struct
*tsk
, sigset_t
*which
)
2429 struct task_struct
*t
;
2431 sigandsets(&retarget
, &tsk
->signal
->shared_pending
.signal
, which
);
2432 if (sigisemptyset(&retarget
))
2436 while_each_thread(tsk
, t
) {
2437 if (t
->flags
& PF_EXITING
)
2440 if (!has_pending_signals(&retarget
, &t
->blocked
))
2442 /* Remove the signals this thread can handle. */
2443 sigandsets(&retarget
, &retarget
, &t
->blocked
);
2445 if (!signal_pending(t
))
2446 signal_wake_up(t
, 0);
2448 if (sigisemptyset(&retarget
))
2453 void exit_signals(struct task_struct
*tsk
)
2459 * @tsk is about to have PF_EXITING set - lock out users which
2460 * expect stable threadgroup.
2462 threadgroup_change_begin(tsk
);
2464 if (thread_group_empty(tsk
) || signal_group_exit(tsk
->signal
)) {
2465 tsk
->flags
|= PF_EXITING
;
2466 threadgroup_change_end(tsk
);
2470 spin_lock_irq(&tsk
->sighand
->siglock
);
2472 * From now this task is not visible for group-wide signals,
2473 * see wants_signal(), do_signal_stop().
2475 tsk
->flags
|= PF_EXITING
;
2477 threadgroup_change_end(tsk
);
2479 if (!signal_pending(tsk
))
2482 unblocked
= tsk
->blocked
;
2483 signotset(&unblocked
);
2484 retarget_shared_pending(tsk
, &unblocked
);
2486 if (unlikely(tsk
->jobctl
& JOBCTL_STOP_PENDING
) &&
2487 task_participate_group_stop(tsk
))
2488 group_stop
= CLD_STOPPED
;
2490 spin_unlock_irq(&tsk
->sighand
->siglock
);
2493 * If group stop has completed, deliver the notification. This
2494 * should always go to the real parent of the group leader.
2496 if (unlikely(group_stop
)) {
2497 read_lock(&tasklist_lock
);
2498 do_notify_parent_cldstop(tsk
, false, group_stop
);
2499 read_unlock(&tasklist_lock
);
2503 EXPORT_SYMBOL(recalc_sigpending
);
2504 EXPORT_SYMBOL_GPL(dequeue_signal
);
2505 EXPORT_SYMBOL(flush_signals
);
2506 EXPORT_SYMBOL(force_sig
);
2507 EXPORT_SYMBOL(send_sig
);
2508 EXPORT_SYMBOL(send_sig_info
);
2509 EXPORT_SYMBOL(sigprocmask
);
2512 * System call entry points.
2516 * sys_restart_syscall - restart a system call
2518 SYSCALL_DEFINE0(restart_syscall
)
2520 struct restart_block
*restart
= ¤t
->restart_block
;
2521 return restart
->fn(restart
);
2524 long do_no_restart_syscall(struct restart_block
*param
)
2529 static void __set_task_blocked(struct task_struct
*tsk
, const sigset_t
*newset
)
2531 if (signal_pending(tsk
) && !thread_group_empty(tsk
)) {
2532 sigset_t newblocked
;
2533 /* A set of now blocked but previously unblocked signals. */
2534 sigandnsets(&newblocked
, newset
, ¤t
->blocked
);
2535 retarget_shared_pending(tsk
, &newblocked
);
2537 tsk
->blocked
= *newset
;
2538 recalc_sigpending();
2542 * set_current_blocked - change current->blocked mask
2545 * It is wrong to change ->blocked directly, this helper should be used
2546 * to ensure the process can't miss a shared signal we are going to block.
2548 void set_current_blocked(sigset_t
*newset
)
2550 sigdelsetmask(newset
, sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2551 __set_current_blocked(newset
);
2554 void __set_current_blocked(const sigset_t
*newset
)
2556 struct task_struct
*tsk
= current
;
2559 * In case the signal mask hasn't changed, there is nothing we need
2560 * to do. The current->blocked shouldn't be modified by other task.
2562 if (sigequalsets(&tsk
->blocked
, newset
))
2565 spin_lock_irq(&tsk
->sighand
->siglock
);
2566 __set_task_blocked(tsk
, newset
);
2567 spin_unlock_irq(&tsk
->sighand
->siglock
);
2571 * This is also useful for kernel threads that want to temporarily
2572 * (or permanently) block certain signals.
2574 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2575 * interface happily blocks "unblockable" signals like SIGKILL
2578 int sigprocmask(int how
, sigset_t
*set
, sigset_t
*oldset
)
2580 struct task_struct
*tsk
= current
;
2583 /* Lockless, only current can change ->blocked, never from irq */
2585 *oldset
= tsk
->blocked
;
2589 sigorsets(&newset
, &tsk
->blocked
, set
);
2592 sigandnsets(&newset
, &tsk
->blocked
, set
);
2601 __set_current_blocked(&newset
);
2606 * sys_rt_sigprocmask - change the list of currently blocked signals
2607 * @how: whether to add, remove, or set signals
2608 * @nset: stores pending signals
2609 * @oset: previous value of signal mask if non-null
2610 * @sigsetsize: size of sigset_t type
2612 SYSCALL_DEFINE4(rt_sigprocmask
, int, how
, sigset_t __user
*, nset
,
2613 sigset_t __user
*, oset
, size_t, sigsetsize
)
2615 sigset_t old_set
, new_set
;
2618 /* XXX: Don't preclude handling different sized sigset_t's. */
2619 if (sigsetsize
!= sizeof(sigset_t
))
2622 old_set
= current
->blocked
;
2625 if (copy_from_user(&new_set
, nset
, sizeof(sigset_t
)))
2627 sigdelsetmask(&new_set
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2629 error
= sigprocmask(how
, &new_set
, NULL
);
2635 if (copy_to_user(oset
, &old_set
, sizeof(sigset_t
)))
2642 #ifdef CONFIG_COMPAT
2643 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask
, int, how
, compat_sigset_t __user
*, nset
,
2644 compat_sigset_t __user
*, oset
, compat_size_t
, sigsetsize
)
2647 sigset_t old_set
= current
->blocked
;
2649 /* XXX: Don't preclude handling different sized sigset_t's. */
2650 if (sigsetsize
!= sizeof(sigset_t
))
2654 compat_sigset_t new32
;
2657 if (copy_from_user(&new32
, nset
, sizeof(compat_sigset_t
)))
2660 sigset_from_compat(&new_set
, &new32
);
2661 sigdelsetmask(&new_set
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2663 error
= sigprocmask(how
, &new_set
, NULL
);
2668 compat_sigset_t old32
;
2669 sigset_to_compat(&old32
, &old_set
);
2670 if (copy_to_user(oset
, &old32
, sizeof(compat_sigset_t
)))
2675 return sys_rt_sigprocmask(how
, (sigset_t __user
*)nset
,
2676 (sigset_t __user
*)oset
, sigsetsize
);
2681 static int do_sigpending(void *set
, unsigned long sigsetsize
)
2683 if (sigsetsize
> sizeof(sigset_t
))
2686 spin_lock_irq(¤t
->sighand
->siglock
);
2687 sigorsets(set
, ¤t
->pending
.signal
,
2688 ¤t
->signal
->shared_pending
.signal
);
2689 spin_unlock_irq(¤t
->sighand
->siglock
);
2691 /* Outside the lock because only this thread touches it. */
2692 sigandsets(set
, ¤t
->blocked
, set
);
2697 * sys_rt_sigpending - examine a pending signal that has been raised
2699 * @uset: stores pending signals
2700 * @sigsetsize: size of sigset_t type or larger
2702 SYSCALL_DEFINE2(rt_sigpending
, sigset_t __user
*, uset
, size_t, sigsetsize
)
2705 int err
= do_sigpending(&set
, sigsetsize
);
2706 if (!err
&& copy_to_user(uset
, &set
, sigsetsize
))
2711 #ifdef CONFIG_COMPAT
2712 COMPAT_SYSCALL_DEFINE2(rt_sigpending
, compat_sigset_t __user
*, uset
,
2713 compat_size_t
, sigsetsize
)
2717 int err
= do_sigpending(&set
, sigsetsize
);
2719 compat_sigset_t set32
;
2720 sigset_to_compat(&set32
, &set
);
2721 /* we can get here only if sigsetsize <= sizeof(set) */
2722 if (copy_to_user(uset
, &set32
, sigsetsize
))
2727 return sys_rt_sigpending((sigset_t __user
*)uset
, sigsetsize
);
2732 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2734 int copy_siginfo_to_user(siginfo_t __user
*to
, const siginfo_t
*from
)
2738 if (!access_ok (VERIFY_WRITE
, to
, sizeof(siginfo_t
)))
2740 if (from
->si_code
< 0)
2741 return __copy_to_user(to
, from
, sizeof(siginfo_t
))
2744 * If you change siginfo_t structure, please be sure
2745 * this code is fixed accordingly.
2746 * Please remember to update the signalfd_copyinfo() function
2747 * inside fs/signalfd.c too, in case siginfo_t changes.
2748 * It should never copy any pad contained in the structure
2749 * to avoid security leaks, but must copy the generic
2750 * 3 ints plus the relevant union member.
2752 err
= __put_user(from
->si_signo
, &to
->si_signo
);
2753 err
|= __put_user(from
->si_errno
, &to
->si_errno
);
2754 err
|= __put_user((short)from
->si_code
, &to
->si_code
);
2755 switch (from
->si_code
& __SI_MASK
) {
2757 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2758 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2761 err
|= __put_user(from
->si_tid
, &to
->si_tid
);
2762 err
|= __put_user(from
->si_overrun
, &to
->si_overrun
);
2763 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2766 err
|= __put_user(from
->si_band
, &to
->si_band
);
2767 err
|= __put_user(from
->si_fd
, &to
->si_fd
);
2770 err
|= __put_user(from
->si_addr
, &to
->si_addr
);
2771 #ifdef __ARCH_SI_TRAPNO
2772 err
|= __put_user(from
->si_trapno
, &to
->si_trapno
);
2774 #ifdef BUS_MCEERR_AO
2776 * Other callers might not initialize the si_lsb field,
2777 * so check explicitly for the right codes here.
2779 if (from
->si_signo
== SIGBUS
&&
2780 (from
->si_code
== BUS_MCEERR_AR
|| from
->si_code
== BUS_MCEERR_AO
))
2781 err
|= __put_user(from
->si_addr_lsb
, &to
->si_addr_lsb
);
2784 if (from
->si_signo
== SIGSEGV
&& from
->si_code
== SEGV_BNDERR
) {
2785 err
|= __put_user(from
->si_lower
, &to
->si_lower
);
2786 err
|= __put_user(from
->si_upper
, &to
->si_upper
);
2790 if (from
->si_signo
== SIGSEGV
&& from
->si_code
== SEGV_PKUERR
)
2791 err
|= __put_user(from
->si_pkey
, &to
->si_pkey
);
2795 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2796 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2797 err
|= __put_user(from
->si_status
, &to
->si_status
);
2798 err
|= __put_user(from
->si_utime
, &to
->si_utime
);
2799 err
|= __put_user(from
->si_stime
, &to
->si_stime
);
2801 case __SI_RT
: /* This is not generated by the kernel as of now. */
2802 case __SI_MESGQ
: /* But this is */
2803 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2804 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2805 err
|= __put_user(from
->si_ptr
, &to
->si_ptr
);
2807 #ifdef __ARCH_SIGSYS
2809 err
|= __put_user(from
->si_call_addr
, &to
->si_call_addr
);
2810 err
|= __put_user(from
->si_syscall
, &to
->si_syscall
);
2811 err
|= __put_user(from
->si_arch
, &to
->si_arch
);
2814 default: /* this is just in case for now ... */
2815 err
|= __put_user(from
->si_pid
, &to
->si_pid
);
2816 err
|= __put_user(from
->si_uid
, &to
->si_uid
);
2825 * do_sigtimedwait - wait for queued signals specified in @which
2826 * @which: queued signals to wait for
2827 * @info: if non-null, the signal's siginfo is returned here
2828 * @ts: upper bound on process time suspension
2830 int do_sigtimedwait(const sigset_t
*which
, siginfo_t
*info
,
2831 const struct timespec
*ts
)
2833 ktime_t
*to
= NULL
, timeout
= { .tv64
= KTIME_MAX
};
2834 struct task_struct
*tsk
= current
;
2835 sigset_t mask
= *which
;
2839 if (!timespec_valid(ts
))
2841 timeout
= timespec_to_ktime(*ts
);
2846 * Invert the set of allowed signals to get those we want to block.
2848 sigdelsetmask(&mask
, sigmask(SIGKILL
) | sigmask(SIGSTOP
));
2851 spin_lock_irq(&tsk
->sighand
->siglock
);
2852 sig
= dequeue_signal(tsk
, &mask
, info
);
2853 if (!sig
&& timeout
.tv64
) {
2855 * None ready, temporarily unblock those we're interested
2856 * while we are sleeping in so that we'll be awakened when
2857 * they arrive. Unblocking is always fine, we can avoid
2858 * set_current_blocked().
2860 tsk
->real_blocked
= tsk
->blocked
;
2861 sigandsets(&tsk
->blocked
, &tsk
->blocked
, &mask
);
2862 recalc_sigpending();
2863 spin_unlock_irq(&tsk
->sighand
->siglock
);
2865 __set_current_state(TASK_INTERRUPTIBLE
);
2866 ret
= freezable_schedule_hrtimeout_range(to
, tsk
->timer_slack_ns
,
2868 spin_lock_irq(&tsk
->sighand
->siglock
);
2869 __set_task_blocked(tsk
, &tsk
->real_blocked
);
2870 sigemptyset(&tsk
->real_blocked
);
2871 sig
= dequeue_signal(tsk
, &mask
, info
);
2873 spin_unlock_irq(&tsk
->sighand
->siglock
);
2877 return ret
? -EINTR
: -EAGAIN
;
2881 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2883 * @uthese: queued signals to wait for
2884 * @uinfo: if non-null, the signal's siginfo is returned here
2885 * @uts: upper bound on process time suspension
2886 * @sigsetsize: size of sigset_t type
2888 SYSCALL_DEFINE4(rt_sigtimedwait
, const sigset_t __user
*, uthese
,
2889 siginfo_t __user
*, uinfo
, const struct timespec __user
*, uts
,
2897 /* XXX: Don't preclude handling different sized sigset_t's. */
2898 if (sigsetsize
!= sizeof(sigset_t
))
2901 if (copy_from_user(&these
, uthese
, sizeof(these
)))
2905 if (copy_from_user(&ts
, uts
, sizeof(ts
)))
2909 ret
= do_sigtimedwait(&these
, &info
, uts
? &ts
: NULL
);
2911 if (ret
> 0 && uinfo
) {
2912 if (copy_siginfo_to_user(uinfo
, &info
))
2920 * sys_kill - send a signal to a process
2921 * @pid: the PID of the process
2922 * @sig: signal to be sent
2924 SYSCALL_DEFINE2(kill
, pid_t
, pid
, int, sig
)
2926 struct siginfo info
;
2928 info
.si_signo
= sig
;
2930 info
.si_code
= SI_USER
;
2931 info
.si_pid
= task_tgid_vnr(current
);
2932 info
.si_uid
= from_kuid_munged(current_user_ns(), current_uid());
2934 return kill_something_info(sig
, &info
, pid
);
2938 do_send_specific(pid_t tgid
, pid_t pid
, int sig
, struct siginfo
*info
)
2940 struct task_struct
*p
;
2944 p
= find_task_by_vpid(pid
);
2945 if (p
&& (tgid
<= 0 || task_tgid_vnr(p
) == tgid
)) {
2946 error
= check_kill_permission(sig
, info
, p
);
2948 * The null signal is a permissions and process existence
2949 * probe. No signal is actually delivered.
2951 if (!error
&& sig
) {
2952 error
= do_send_sig_info(sig
, info
, p
, false);
2954 * If lock_task_sighand() failed we pretend the task
2955 * dies after receiving the signal. The window is tiny,
2956 * and the signal is private anyway.
2958 if (unlikely(error
== -ESRCH
))
2967 static int do_tkill(pid_t tgid
, pid_t pid
, int sig
)
2969 struct siginfo info
= {};
2971 info
.si_signo
= sig
;
2973 info
.si_code
= SI_TKILL
;
2974 info
.si_pid
= task_tgid_vnr(current
);
2975 info
.si_uid
= from_kuid_munged(current_user_ns(), current_uid());
2977 return do_send_specific(tgid
, pid
, sig
, &info
);
2981 * sys_tgkill - send signal to one specific thread
2982 * @tgid: the thread group ID of the thread
2983 * @pid: the PID of the thread
2984 * @sig: signal to be sent
2986 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2987 * exists but it's not belonging to the target process anymore. This
2988 * method solves the problem of threads exiting and PIDs getting reused.
2990 SYSCALL_DEFINE3(tgkill
, pid_t
, tgid
, pid_t
, pid
, int, sig
)
2992 /* This is only valid for single tasks */
2993 if (pid
<= 0 || tgid
<= 0)
2996 return do_tkill(tgid
, pid
, sig
);
3000 * sys_tkill - send signal to one specific task
3001 * @pid: the PID of the task
3002 * @sig: signal to be sent
3004 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3006 SYSCALL_DEFINE2(tkill
, pid_t
, pid
, int, sig
)
3008 /* This is only valid for single tasks */
3012 return do_tkill(0, pid
, sig
);
3015 static int do_rt_sigqueueinfo(pid_t pid
, int sig
, siginfo_t
*info
)
3017 /* Not even root can pretend to send signals from the kernel.
3018 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3020 if ((info
->si_code
>= 0 || info
->si_code
== SI_TKILL
) &&
3021 (task_pid_vnr(current
) != pid
))
3024 info
->si_signo
= sig
;
3026 /* POSIX.1b doesn't mention process groups. */
3027 return kill_proc_info(sig
, info
, pid
);
3031 * sys_rt_sigqueueinfo - send signal information to a signal
3032 * @pid: the PID of the thread
3033 * @sig: signal to be sent
3034 * @uinfo: signal info to be sent
3036 SYSCALL_DEFINE3(rt_sigqueueinfo
, pid_t
, pid
, int, sig
,
3037 siginfo_t __user
*, uinfo
)
3040 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
3042 return do_rt_sigqueueinfo(pid
, sig
, &info
);
3045 #ifdef CONFIG_COMPAT
3046 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo
,
3049 struct compat_siginfo __user
*, uinfo
)
3051 siginfo_t info
= {};
3052 int ret
= copy_siginfo_from_user32(&info
, uinfo
);
3055 return do_rt_sigqueueinfo(pid
, sig
, &info
);
3059 static int do_rt_tgsigqueueinfo(pid_t tgid
, pid_t pid
, int sig
, siginfo_t
*info
)
3061 /* This is only valid for single tasks */
3062 if (pid
<= 0 || tgid
<= 0)
3065 /* Not even root can pretend to send signals from the kernel.
3066 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3068 if ((info
->si_code
>= 0 || info
->si_code
== SI_TKILL
) &&
3069 (task_pid_vnr(current
) != pid
))
3072 info
->si_signo
= sig
;
3074 return do_send_specific(tgid
, pid
, sig
, info
);
3077 SYSCALL_DEFINE4(rt_tgsigqueueinfo
, pid_t
, tgid
, pid_t
, pid
, int, sig
,
3078 siginfo_t __user
*, uinfo
)
3082 if (copy_from_user(&info
, uinfo
, sizeof(siginfo_t
)))
3085 return do_rt_tgsigqueueinfo(tgid
, pid
, sig
, &info
);
3088 #ifdef CONFIG_COMPAT
3089 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo
,
3093 struct compat_siginfo __user
*, uinfo
)
3095 siginfo_t info
= {};
3097 if (copy_siginfo_from_user32(&info
, uinfo
))
3099 return do_rt_tgsigqueueinfo(tgid
, pid
, sig
, &info
);
3104 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3106 void kernel_sigaction(int sig
, __sighandler_t action
)
3108 spin_lock_irq(¤t
->sighand
->siglock
);
3109 current
->sighand
->action
[sig
- 1].sa
.sa_handler
= action
;
3110 if (action
== SIG_IGN
) {
3114 sigaddset(&mask
, sig
);
3116 flush_sigqueue_mask(&mask
, ¤t
->signal
->shared_pending
);
3117 flush_sigqueue_mask(&mask
, ¤t
->pending
);
3118 recalc_sigpending();
3120 spin_unlock_irq(¤t
->sighand
->siglock
);
3122 EXPORT_SYMBOL(kernel_sigaction
);
3124 void __weak
sigaction_compat_abi(struct k_sigaction
*act
,
3125 struct k_sigaction
*oact
)
3129 int do_sigaction(int sig
, struct k_sigaction
*act
, struct k_sigaction
*oact
)
3131 struct task_struct
*p
= current
, *t
;
3132 struct k_sigaction
*k
;
3135 if (!valid_signal(sig
) || sig
< 1 || (act
&& sig_kernel_only(sig
)))
3138 k
= &p
->sighand
->action
[sig
-1];
3140 spin_lock_irq(&p
->sighand
->siglock
);
3144 sigaction_compat_abi(act
, oact
);
3147 sigdelsetmask(&act
->sa
.sa_mask
,
3148 sigmask(SIGKILL
) | sigmask(SIGSTOP
));
3152 * "Setting a signal action to SIG_IGN for a signal that is
3153 * pending shall cause the pending signal to be discarded,
3154 * whether or not it is blocked."
3156 * "Setting a signal action to SIG_DFL for a signal that is
3157 * pending and whose default action is to ignore the signal
3158 * (for example, SIGCHLD), shall cause the pending signal to
3159 * be discarded, whether or not it is blocked"
3161 if (sig_handler_ignored(sig_handler(p
, sig
), sig
)) {
3163 sigaddset(&mask
, sig
);
3164 flush_sigqueue_mask(&mask
, &p
->signal
->shared_pending
);
3165 for_each_thread(p
, t
)
3166 flush_sigqueue_mask(&mask
, &t
->pending
);
3170 spin_unlock_irq(&p
->sighand
->siglock
);
3175 do_sigaltstack (const stack_t __user
*uss
, stack_t __user
*uoss
, unsigned long sp
,
3181 oss
.ss_sp
= (void __user
*) current
->sas_ss_sp
;
3182 oss
.ss_size
= current
->sas_ss_size
;
3183 oss
.ss_flags
= sas_ss_flags(sp
) |
3184 (current
->sas_ss_flags
& SS_FLAG_BITS
);
3193 if (!access_ok(VERIFY_READ
, uss
, sizeof(*uss
)))
3195 error
= __get_user(ss_sp
, &uss
->ss_sp
) |
3196 __get_user(ss_flags
, &uss
->ss_flags
) |
3197 __get_user(ss_size
, &uss
->ss_size
);
3202 if (on_sig_stack(sp
))
3205 ss_mode
= ss_flags
& ~SS_FLAG_BITS
;
3207 if (ss_mode
!= SS_DISABLE
&& ss_mode
!= SS_ONSTACK
&&
3211 if (ss_mode
== SS_DISABLE
) {
3215 if (unlikely(ss_size
< min_ss_size
))
3219 current
->sas_ss_sp
= (unsigned long) ss_sp
;
3220 current
->sas_ss_size
= ss_size
;
3221 current
->sas_ss_flags
= ss_flags
;
3227 if (!access_ok(VERIFY_WRITE
, uoss
, sizeof(*uoss
)))
3229 error
= __put_user(oss
.ss_sp
, &uoss
->ss_sp
) |
3230 __put_user(oss
.ss_size
, &uoss
->ss_size
) |
3231 __put_user(oss
.ss_flags
, &uoss
->ss_flags
);
3237 SYSCALL_DEFINE2(sigaltstack
,const stack_t __user
*,uss
, stack_t __user
*,uoss
)
3239 return do_sigaltstack(uss
, uoss
, current_user_stack_pointer(),
3243 int restore_altstack(const stack_t __user
*uss
)
3245 int err
= do_sigaltstack(uss
, NULL
, current_user_stack_pointer(),
3247 /* squash all but EFAULT for now */
3248 return err
== -EFAULT
? err
: 0;
3251 int __save_altstack(stack_t __user
*uss
, unsigned long sp
)
3253 struct task_struct
*t
= current
;
3254 int err
= __put_user((void __user
*)t
->sas_ss_sp
, &uss
->ss_sp
) |
3255 __put_user(t
->sas_ss_flags
, &uss
->ss_flags
) |
3256 __put_user(t
->sas_ss_size
, &uss
->ss_size
);
3259 if (t
->sas_ss_flags
& SS_AUTODISARM
)
3264 #ifdef CONFIG_COMPAT
3265 COMPAT_SYSCALL_DEFINE2(sigaltstack
,
3266 const compat_stack_t __user
*, uss_ptr
,
3267 compat_stack_t __user
*, uoss_ptr
)
3274 compat_stack_t uss32
;
3276 memset(&uss
, 0, sizeof(stack_t
));
3277 if (copy_from_user(&uss32
, uss_ptr
, sizeof(compat_stack_t
)))
3279 uss
.ss_sp
= compat_ptr(uss32
.ss_sp
);
3280 uss
.ss_flags
= uss32
.ss_flags
;
3281 uss
.ss_size
= uss32
.ss_size
;
3285 ret
= do_sigaltstack((stack_t __force __user
*) (uss_ptr
? &uss
: NULL
),
3286 (stack_t __force __user
*) &uoss
,
3287 compat_user_stack_pointer(),
3288 COMPAT_MINSIGSTKSZ
);
3290 if (ret
>= 0 && uoss_ptr
) {
3291 if (!access_ok(VERIFY_WRITE
, uoss_ptr
, sizeof(compat_stack_t
)) ||
3292 __put_user(ptr_to_compat(uoss
.ss_sp
), &uoss_ptr
->ss_sp
) ||
3293 __put_user(uoss
.ss_flags
, &uoss_ptr
->ss_flags
) ||
3294 __put_user(uoss
.ss_size
, &uoss_ptr
->ss_size
))
3300 int compat_restore_altstack(const compat_stack_t __user
*uss
)
3302 int err
= compat_sys_sigaltstack(uss
, NULL
);
3303 /* squash all but -EFAULT for now */
3304 return err
== -EFAULT
? err
: 0;
3307 int __compat_save_altstack(compat_stack_t __user
*uss
, unsigned long sp
)
3310 struct task_struct
*t
= current
;
3311 err
= __put_user(ptr_to_compat((void __user
*)t
->sas_ss_sp
),
3313 __put_user(t
->sas_ss_flags
, &uss
->ss_flags
) |
3314 __put_user(t
->sas_ss_size
, &uss
->ss_size
);
3317 if (t
->sas_ss_flags
& SS_AUTODISARM
)
3323 #ifdef __ARCH_WANT_SYS_SIGPENDING
3326 * sys_sigpending - examine pending signals
3327 * @set: where mask of pending signal is returned
3329 SYSCALL_DEFINE1(sigpending
, old_sigset_t __user
*, set
)
3331 return sys_rt_sigpending((sigset_t __user
*)set
, sizeof(old_sigset_t
));
3336 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3338 * sys_sigprocmask - examine and change blocked signals
3339 * @how: whether to add, remove, or set signals
3340 * @nset: signals to add or remove (if non-null)
3341 * @oset: previous value of signal mask if non-null
3343 * Some platforms have their own version with special arguments;
3344 * others support only sys_rt_sigprocmask.
3347 SYSCALL_DEFINE3(sigprocmask
, int, how
, old_sigset_t __user
*, nset
,
3348 old_sigset_t __user
*, oset
)
3350 old_sigset_t old_set
, new_set
;
3351 sigset_t new_blocked
;
3353 old_set
= current
->blocked
.sig
[0];
3356 if (copy_from_user(&new_set
, nset
, sizeof(*nset
)))
3359 new_blocked
= current
->blocked
;
3363 sigaddsetmask(&new_blocked
, new_set
);
3366 sigdelsetmask(&new_blocked
, new_set
);
3369 new_blocked
.sig
[0] = new_set
;
3375 set_current_blocked(&new_blocked
);
3379 if (copy_to_user(oset
, &old_set
, sizeof(*oset
)))
3385 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3387 #ifndef CONFIG_ODD_RT_SIGACTION
3389 * sys_rt_sigaction - alter an action taken by a process
3390 * @sig: signal to be sent
3391 * @act: new sigaction
3392 * @oact: used to save the previous sigaction
3393 * @sigsetsize: size of sigset_t type
3395 SYSCALL_DEFINE4(rt_sigaction
, int, sig
,
3396 const struct sigaction __user
*, act
,
3397 struct sigaction __user
*, oact
,
3400 struct k_sigaction new_sa
, old_sa
;
3403 /* XXX: Don't preclude handling different sized sigset_t's. */
3404 if (sigsetsize
!= sizeof(sigset_t
))
3408 if (copy_from_user(&new_sa
.sa
, act
, sizeof(new_sa
.sa
)))
3412 ret
= do_sigaction(sig
, act
? &new_sa
: NULL
, oact
? &old_sa
: NULL
);
3415 if (copy_to_user(oact
, &old_sa
.sa
, sizeof(old_sa
.sa
)))
3421 #ifdef CONFIG_COMPAT
3422 COMPAT_SYSCALL_DEFINE4(rt_sigaction
, int, sig
,
3423 const struct compat_sigaction __user
*, act
,
3424 struct compat_sigaction __user
*, oact
,
3425 compat_size_t
, sigsetsize
)
3427 struct k_sigaction new_ka
, old_ka
;
3428 compat_sigset_t mask
;
3429 #ifdef __ARCH_HAS_SA_RESTORER
3430 compat_uptr_t restorer
;
3434 /* XXX: Don't preclude handling different sized sigset_t's. */
3435 if (sigsetsize
!= sizeof(compat_sigset_t
))
3439 compat_uptr_t handler
;
3440 ret
= get_user(handler
, &act
->sa_handler
);
3441 new_ka
.sa
.sa_handler
= compat_ptr(handler
);
3442 #ifdef __ARCH_HAS_SA_RESTORER
3443 ret
|= get_user(restorer
, &act
->sa_restorer
);
3444 new_ka
.sa
.sa_restorer
= compat_ptr(restorer
);
3446 ret
|= copy_from_user(&mask
, &act
->sa_mask
, sizeof(mask
));
3447 ret
|= get_user(new_ka
.sa
.sa_flags
, &act
->sa_flags
);
3450 sigset_from_compat(&new_ka
.sa
.sa_mask
, &mask
);
3453 ret
= do_sigaction(sig
, act
? &new_ka
: NULL
, oact
? &old_ka
: NULL
);
3455 sigset_to_compat(&mask
, &old_ka
.sa
.sa_mask
);
3456 ret
= put_user(ptr_to_compat(old_ka
.sa
.sa_handler
),
3458 ret
|= copy_to_user(&oact
->sa_mask
, &mask
, sizeof(mask
));
3459 ret
|= put_user(old_ka
.sa
.sa_flags
, &oact
->sa_flags
);
3460 #ifdef __ARCH_HAS_SA_RESTORER
3461 ret
|= put_user(ptr_to_compat(old_ka
.sa
.sa_restorer
),
3462 &oact
->sa_restorer
);
3468 #endif /* !CONFIG_ODD_RT_SIGACTION */
3470 #ifdef CONFIG_OLD_SIGACTION
3471 SYSCALL_DEFINE3(sigaction
, int, sig
,
3472 const struct old_sigaction __user
*, act
,
3473 struct old_sigaction __user
*, oact
)
3475 struct k_sigaction new_ka
, old_ka
;
3480 if (!access_ok(VERIFY_READ
, act
, sizeof(*act
)) ||
3481 __get_user(new_ka
.sa
.sa_handler
, &act
->sa_handler
) ||
3482 __get_user(new_ka
.sa
.sa_restorer
, &act
->sa_restorer
) ||
3483 __get_user(new_ka
.sa
.sa_flags
, &act
->sa_flags
) ||
3484 __get_user(mask
, &act
->sa_mask
))
3486 #ifdef __ARCH_HAS_KA_RESTORER
3487 new_ka
.ka_restorer
= NULL
;
3489 siginitset(&new_ka
.sa
.sa_mask
, mask
);
3492 ret
= do_sigaction(sig
, act
? &new_ka
: NULL
, oact
? &old_ka
: NULL
);
3495 if (!access_ok(VERIFY_WRITE
, oact
, sizeof(*oact
)) ||
3496 __put_user(old_ka
.sa
.sa_handler
, &oact
->sa_handler
) ||
3497 __put_user(old_ka
.sa
.sa_restorer
, &oact
->sa_restorer
) ||
3498 __put_user(old_ka
.sa
.sa_flags
, &oact
->sa_flags
) ||
3499 __put_user(old_ka
.sa
.sa_mask
.sig
[0], &oact
->sa_mask
))
3506 #ifdef CONFIG_COMPAT_OLD_SIGACTION
3507 COMPAT_SYSCALL_DEFINE3(sigaction
, int, sig
,
3508 const struct compat_old_sigaction __user
*, act
,
3509 struct compat_old_sigaction __user
*, oact
)
3511 struct k_sigaction new_ka
, old_ka
;
3513 compat_old_sigset_t mask
;
3514 compat_uptr_t handler
, restorer
;
3517 if (!access_ok(VERIFY_READ
, act
, sizeof(*act
)) ||
3518 __get_user(handler
, &act
->sa_handler
) ||
3519 __get_user(restorer
, &act
->sa_restorer
) ||
3520 __get_user(new_ka
.sa
.sa_flags
, &act
->sa_flags
) ||
3521 __get_user(mask
, &act
->sa_mask
))
3524 #ifdef __ARCH_HAS_KA_RESTORER
3525 new_ka
.ka_restorer
= NULL
;
3527 new_ka
.sa
.sa_handler
= compat_ptr(handler
);
3528 new_ka
.sa
.sa_restorer
= compat_ptr(restorer
);
3529 siginitset(&new_ka
.sa
.sa_mask
, mask
);
3532 ret
= do_sigaction(sig
, act
? &new_ka
: NULL
, oact
? &old_ka
: NULL
);
3535 if (!access_ok(VERIFY_WRITE
, oact
, sizeof(*oact
)) ||
3536 __put_user(ptr_to_compat(old_ka
.sa
.sa_handler
),
3537 &oact
->sa_handler
) ||
3538 __put_user(ptr_to_compat(old_ka
.sa
.sa_restorer
),
3539 &oact
->sa_restorer
) ||
3540 __put_user(old_ka
.sa
.sa_flags
, &oact
->sa_flags
) ||
3541 __put_user(old_ka
.sa
.sa_mask
.sig
[0], &oact
->sa_mask
))
3548 #ifdef CONFIG_SGETMASK_SYSCALL
3551 * For backwards compatibility. Functionality superseded by sigprocmask.
3553 SYSCALL_DEFINE0(sgetmask
)
3556 return current
->blocked
.sig
[0];
3559 SYSCALL_DEFINE1(ssetmask
, int, newmask
)
3561 int old
= current
->blocked
.sig
[0];
3564 siginitset(&newset
, newmask
);
3565 set_current_blocked(&newset
);
3569 #endif /* CONFIG_SGETMASK_SYSCALL */
3571 #ifdef __ARCH_WANT_SYS_SIGNAL
3573 * For backwards compatibility. Functionality superseded by sigaction.
3575 SYSCALL_DEFINE2(signal
, int, sig
, __sighandler_t
, handler
)
3577 struct k_sigaction new_sa
, old_sa
;
3580 new_sa
.sa
.sa_handler
= handler
;
3581 new_sa
.sa
.sa_flags
= SA_ONESHOT
| SA_NOMASK
;
3582 sigemptyset(&new_sa
.sa
.sa_mask
);
3584 ret
= do_sigaction(sig
, &new_sa
, &old_sa
);
3586 return ret
? ret
: (unsigned long)old_sa
.sa
.sa_handler
;
3588 #endif /* __ARCH_WANT_SYS_SIGNAL */
3590 #ifdef __ARCH_WANT_SYS_PAUSE
3592 SYSCALL_DEFINE0(pause
)
3594 while (!signal_pending(current
)) {
3595 __set_current_state(TASK_INTERRUPTIBLE
);
3598 return -ERESTARTNOHAND
;
3603 static int sigsuspend(sigset_t
*set
)
3605 current
->saved_sigmask
= current
->blocked
;
3606 set_current_blocked(set
);
3608 while (!signal_pending(current
)) {
3609 __set_current_state(TASK_INTERRUPTIBLE
);
3612 set_restore_sigmask();
3613 return -ERESTARTNOHAND
;
3617 * sys_rt_sigsuspend - replace the signal mask for a value with the
3618 * @unewset value until a signal is received
3619 * @unewset: new signal mask value
3620 * @sigsetsize: size of sigset_t type
3622 SYSCALL_DEFINE2(rt_sigsuspend
, sigset_t __user
*, unewset
, size_t, sigsetsize
)
3626 /* XXX: Don't preclude handling different sized sigset_t's. */
3627 if (sigsetsize
!= sizeof(sigset_t
))
3630 if (copy_from_user(&newset
, unewset
, sizeof(newset
)))
3632 return sigsuspend(&newset
);
3635 #ifdef CONFIG_COMPAT
3636 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend
, compat_sigset_t __user
*, unewset
, compat_size_t
, sigsetsize
)
3640 compat_sigset_t newset32
;
3642 /* XXX: Don't preclude handling different sized sigset_t's. */
3643 if (sigsetsize
!= sizeof(sigset_t
))
3646 if (copy_from_user(&newset32
, unewset
, sizeof(compat_sigset_t
)))
3648 sigset_from_compat(&newset
, &newset32
);
3649 return sigsuspend(&newset
);
3651 /* on little-endian bitmaps don't care about granularity */
3652 return sys_rt_sigsuspend((sigset_t __user
*)unewset
, sigsetsize
);
3657 #ifdef CONFIG_OLD_SIGSUSPEND
3658 SYSCALL_DEFINE1(sigsuspend
, old_sigset_t
, mask
)
3661 siginitset(&blocked
, mask
);
3662 return sigsuspend(&blocked
);
3665 #ifdef CONFIG_OLD_SIGSUSPEND3
3666 SYSCALL_DEFINE3(sigsuspend
, int, unused1
, int, unused2
, old_sigset_t
, mask
)
3669 siginitset(&blocked
, mask
);
3670 return sigsuspend(&blocked
);
3674 __weak
const char *arch_vma_name(struct vm_area_struct
*vma
)
3679 void __init
signals_init(void)
3681 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3682 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3683 != offsetof(struct siginfo
, _sifields
._pad
));
3685 sigqueue_cachep
= KMEM_CACHE(sigqueue
, SLAB_PANIC
);
3688 #ifdef CONFIG_KGDB_KDB
3689 #include <linux/kdb.h>
3691 * kdb_send_sig_info - Allows kdb to send signals without exposing
3692 * signal internals. This function checks if the required locks are
3693 * available before calling the main signal code, to avoid kdb
3697 kdb_send_sig_info(struct task_struct
*t
, struct siginfo
*info
)
3699 static struct task_struct
*kdb_prev_t
;
3701 if (!spin_trylock(&t
->sighand
->siglock
)) {
3702 kdb_printf("Can't do kill command now.\n"
3703 "The sigmask lock is held somewhere else in "
3704 "kernel, try again later\n");
3707 spin_unlock(&t
->sighand
->siglock
);
3708 new_t
= kdb_prev_t
!= t
;
3710 if (t
->state
!= TASK_RUNNING
&& new_t
) {
3711 kdb_printf("Process is not RUNNING, sending a signal from "
3712 "kdb risks deadlock\n"
3713 "on the run queue locks. "
3714 "The signal has _not_ been sent.\n"
3715 "Reissue the kill command if you want to risk "
3719 sig
= info
->si_signo
;
3720 if (send_sig_info(sig
, info
, t
))
3721 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3724 kdb_printf("Signal %d is sent to process %d.\n", sig
, t
->pid
);
3726 #endif /* CONFIG_KGDB_KDB */