Loading...
1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.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>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <linux/uaccess.h>
43#include <asm/unistd.h>
44#include <asm/siginfo.h>
45#include <asm/cacheflush.h>
46#include "audit.h" /* audit_signal_info() */
47
48/*
49 * SLAB caches for signal bits.
50 */
51
52static struct kmem_cache *sigqueue_cachep;
53
54int print_fatal_signals __read_mostly;
55
56static void __user *sig_handler(struct task_struct *t, int sig)
57{
58 return t->sighand->action[sig - 1].sa.sa_handler;
59}
60
61static int sig_handler_ignored(void __user *handler, int sig)
62{
63 /* Is it explicitly or implicitly ignored? */
64 return handler == SIG_IGN ||
65 (handler == SIG_DFL && sig_kernel_ignore(sig));
66}
67
68static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69{
70 void __user *handler;
71
72 handler = sig_handler(t, sig);
73
74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 handler == SIG_DFL && !force)
76 return 1;
77
78 return sig_handler_ignored(handler, sig);
79}
80
81static int sig_ignored(struct task_struct *t, int sig, bool force)
82{
83 /*
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
86 * unblocked.
87 */
88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 return 0;
90
91 if (!sig_task_ignored(t, sig, force))
92 return 0;
93
94 /*
95 * Tracers may want to know about even ignored signals.
96 */
97 return !t->ptrace;
98}
99
100/*
101 * Re-calculate pending state from the set of locally pending
102 * signals, globally pending signals, and blocked signals.
103 */
104static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105{
106 unsigned long ready;
107 long i;
108
109 switch (_NSIG_WORDS) {
110 default:
111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 ready |= signal->sig[i] &~ blocked->sig[i];
113 break;
114
115 case 4: ready = signal->sig[3] &~ blocked->sig[3];
116 ready |= signal->sig[2] &~ blocked->sig[2];
117 ready |= signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
119 break;
120
121 case 2: ready = signal->sig[1] &~ blocked->sig[1];
122 ready |= signal->sig[0] &~ blocked->sig[0];
123 break;
124
125 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 }
127 return ready != 0;
128}
129
130#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131
132static int recalc_sigpending_tsk(struct task_struct *t)
133{
134 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 PENDING(&t->pending, &t->blocked) ||
136 PENDING(&t->signal->shared_pending, &t->blocked)) {
137 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 return 1;
139 }
140 /*
141 * We must never clear the flag in another thread, or in current
142 * when it's possible the current syscall is returning -ERESTART*.
143 * So we don't clear it here, and only callers who know they should do.
144 */
145 return 0;
146}
147
148/*
149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150 * This is superfluous when called on current, the wakeup is a harmless no-op.
151 */
152void recalc_sigpending_and_wake(struct task_struct *t)
153{
154 if (recalc_sigpending_tsk(t))
155 signal_wake_up(t, 0);
156}
157
158void recalc_sigpending(void)
159{
160 if (!recalc_sigpending_tsk(current) && !freezing(current))
161 clear_thread_flag(TIF_SIGPENDING);
162
163}
164
165/* Given the mask, find the first available signal that should be serviced. */
166
167#define SYNCHRONOUS_MASK \
168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170
171int next_signal(struct sigpending *pending, sigset_t *mask)
172{
173 unsigned long i, *s, *m, x;
174 int sig = 0;
175
176 s = pending->signal.sig;
177 m = mask->sig;
178
179 /*
180 * Handle the first word specially: it contains the
181 * synchronous signals that need to be dequeued first.
182 */
183 x = *s &~ *m;
184 if (x) {
185 if (x & SYNCHRONOUS_MASK)
186 x &= SYNCHRONOUS_MASK;
187 sig = ffz(~x) + 1;
188 return sig;
189 }
190
191 switch (_NSIG_WORDS) {
192 default:
193 for (i = 1; i < _NSIG_WORDS; ++i) {
194 x = *++s &~ *++m;
195 if (!x)
196 continue;
197 sig = ffz(~x) + i*_NSIG_BPW + 1;
198 break;
199 }
200 break;
201
202 case 2:
203 x = s[1] &~ m[1];
204 if (!x)
205 break;
206 sig = ffz(~x) + _NSIG_BPW + 1;
207 break;
208
209 case 1:
210 /* Nothing to do */
211 break;
212 }
213
214 return sig;
215}
216
217static inline void print_dropped_signal(int sig)
218{
219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220
221 if (!print_fatal_signals)
222 return;
223
224 if (!__ratelimit(&ratelimit_state))
225 return;
226
227 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 current->comm, current->pid, sig);
229}
230
231/**
232 * task_set_jobctl_pending - set jobctl pending bits
233 * @task: target task
234 * @mask: pending bits to set
235 *
236 * Clear @mask from @task->jobctl. @mask must be subset of
237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
239 * cleared. If @task is already being killed or exiting, this function
240 * becomes noop.
241 *
242 * CONTEXT:
243 * Must be called with @task->sighand->siglock held.
244 *
245 * RETURNS:
246 * %true if @mask is set, %false if made noop because @task was dying.
247 */
248bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
249{
250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253
254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 return false;
256
257 if (mask & JOBCTL_STOP_SIGMASK)
258 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259
260 task->jobctl |= mask;
261 return true;
262}
263
264/**
265 * task_clear_jobctl_trapping - clear jobctl trapping bit
266 * @task: target task
267 *
268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269 * Clear it and wake up the ptracer. Note that we don't need any further
270 * locking. @task->siglock guarantees that @task->parent points to the
271 * ptracer.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 */
276void task_clear_jobctl_trapping(struct task_struct *task)
277{
278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 task->jobctl &= ~JOBCTL_TRAPPING;
280 smp_mb(); /* advised by wake_up_bit() */
281 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
282 }
283}
284
285/**
286 * task_clear_jobctl_pending - clear jobctl pending bits
287 * @task: target task
288 * @mask: pending bits to clear
289 *
290 * Clear @mask from @task->jobctl. @mask must be subset of
291 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
292 * STOP bits are cleared together.
293 *
294 * If clearing of @mask leaves no stop or trap pending, this function calls
295 * task_clear_jobctl_trapping().
296 *
297 * CONTEXT:
298 * Must be called with @task->sighand->siglock held.
299 */
300void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
301{
302 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
303
304 if (mask & JOBCTL_STOP_PENDING)
305 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
306
307 task->jobctl &= ~mask;
308
309 if (!(task->jobctl & JOBCTL_PENDING_MASK))
310 task_clear_jobctl_trapping(task);
311}
312
313/**
314 * task_participate_group_stop - participate in a group stop
315 * @task: task participating in a group stop
316 *
317 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
318 * Group stop states are cleared and the group stop count is consumed if
319 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
320 * stop, the appropriate %SIGNAL_* flags are set.
321 *
322 * CONTEXT:
323 * Must be called with @task->sighand->siglock held.
324 *
325 * RETURNS:
326 * %true if group stop completion should be notified to the parent, %false
327 * otherwise.
328 */
329static bool task_participate_group_stop(struct task_struct *task)
330{
331 struct signal_struct *sig = task->signal;
332 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
333
334 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
335
336 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
337
338 if (!consume)
339 return false;
340
341 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
342 sig->group_stop_count--;
343
344 /*
345 * Tell the caller to notify completion iff we are entering into a
346 * fresh group stop. Read comment in do_signal_stop() for details.
347 */
348 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
349 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
350 return true;
351 }
352 return false;
353}
354
355/*
356 * allocate a new signal queue record
357 * - this may be called without locks if and only if t == current, otherwise an
358 * appropriate lock must be held to stop the target task from exiting
359 */
360static struct sigqueue *
361__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
362{
363 struct sigqueue *q = NULL;
364 struct user_struct *user;
365
366 /*
367 * Protect access to @t credentials. This can go away when all
368 * callers hold rcu read lock.
369 */
370 rcu_read_lock();
371 user = get_uid(__task_cred(t)->user);
372 atomic_inc(&user->sigpending);
373 rcu_read_unlock();
374
375 if (override_rlimit ||
376 atomic_read(&user->sigpending) <=
377 task_rlimit(t, RLIMIT_SIGPENDING)) {
378 q = kmem_cache_alloc(sigqueue_cachep, flags);
379 } else {
380 print_dropped_signal(sig);
381 }
382
383 if (unlikely(q == NULL)) {
384 atomic_dec(&user->sigpending);
385 free_uid(user);
386 } else {
387 INIT_LIST_HEAD(&q->list);
388 q->flags = 0;
389 q->user = user;
390 }
391
392 return q;
393}
394
395static void __sigqueue_free(struct sigqueue *q)
396{
397 if (q->flags & SIGQUEUE_PREALLOC)
398 return;
399 atomic_dec(&q->user->sigpending);
400 free_uid(q->user);
401 kmem_cache_free(sigqueue_cachep, q);
402}
403
404void flush_sigqueue(struct sigpending *queue)
405{
406 struct sigqueue *q;
407
408 sigemptyset(&queue->signal);
409 while (!list_empty(&queue->list)) {
410 q = list_entry(queue->list.next, struct sigqueue , list);
411 list_del_init(&q->list);
412 __sigqueue_free(q);
413 }
414}
415
416/*
417 * Flush all pending signals for this kthread.
418 */
419void flush_signals(struct task_struct *t)
420{
421 unsigned long flags;
422
423 spin_lock_irqsave(&t->sighand->siglock, flags);
424 clear_tsk_thread_flag(t, TIF_SIGPENDING);
425 flush_sigqueue(&t->pending);
426 flush_sigqueue(&t->signal->shared_pending);
427 spin_unlock_irqrestore(&t->sighand->siglock, flags);
428}
429
430#ifdef CONFIG_POSIX_TIMERS
431static void __flush_itimer_signals(struct sigpending *pending)
432{
433 sigset_t signal, retain;
434 struct sigqueue *q, *n;
435
436 signal = pending->signal;
437 sigemptyset(&retain);
438
439 list_for_each_entry_safe(q, n, &pending->list, list) {
440 int sig = q->info.si_signo;
441
442 if (likely(q->info.si_code != SI_TIMER)) {
443 sigaddset(&retain, sig);
444 } else {
445 sigdelset(&signal, sig);
446 list_del_init(&q->list);
447 __sigqueue_free(q);
448 }
449 }
450
451 sigorsets(&pending->signal, &signal, &retain);
452}
453
454void flush_itimer_signals(void)
455{
456 struct task_struct *tsk = current;
457 unsigned long flags;
458
459 spin_lock_irqsave(&tsk->sighand->siglock, flags);
460 __flush_itimer_signals(&tsk->pending);
461 __flush_itimer_signals(&tsk->signal->shared_pending);
462 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
463}
464#endif
465
466void ignore_signals(struct task_struct *t)
467{
468 int i;
469
470 for (i = 0; i < _NSIG; ++i)
471 t->sighand->action[i].sa.sa_handler = SIG_IGN;
472
473 flush_signals(t);
474}
475
476/*
477 * Flush all handlers for a task.
478 */
479
480void
481flush_signal_handlers(struct task_struct *t, int force_default)
482{
483 int i;
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;
488 ka->sa.sa_flags = 0;
489#ifdef __ARCH_HAS_SA_RESTORER
490 ka->sa.sa_restorer = NULL;
491#endif
492 sigemptyset(&ka->sa.sa_mask);
493 ka++;
494 }
495}
496
497int unhandled_signal(struct task_struct *tsk, int sig)
498{
499 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
500 if (is_global_init(tsk))
501 return 1;
502 if (handler != SIG_IGN && handler != SIG_DFL)
503 return 0;
504 /* if ptraced, let the tracer determine */
505 return !tsk->ptrace;
506}
507
508static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
509{
510 struct sigqueue *q, *first = NULL;
511
512 /*
513 * Collect the siginfo appropriate to this signal. Check if
514 * there is another siginfo for the same signal.
515 */
516 list_for_each_entry(q, &list->list, list) {
517 if (q->info.si_signo == sig) {
518 if (first)
519 goto still_pending;
520 first = q;
521 }
522 }
523
524 sigdelset(&list->signal, sig);
525
526 if (first) {
527still_pending:
528 list_del_init(&first->list);
529 copy_siginfo(info, &first->info);
530 __sigqueue_free(first);
531 } else {
532 /*
533 * Ok, it wasn't in the queue. This must be
534 * a fast-pathed signal or we must have been
535 * out of queue space. So zero out the info.
536 */
537 info->si_signo = sig;
538 info->si_errno = 0;
539 info->si_code = SI_USER;
540 info->si_pid = 0;
541 info->si_uid = 0;
542 }
543}
544
545static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
546 siginfo_t *info)
547{
548 int sig = next_signal(pending, mask);
549
550 if (sig)
551 collect_signal(sig, pending, info);
552 return sig;
553}
554
555/*
556 * Dequeue a signal and return the element to the caller, which is
557 * expected to free it.
558 *
559 * All callers have to hold the siglock.
560 */
561int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
562{
563 int signr;
564
565 /* We only dequeue private signals from ourselves, we don't let
566 * signalfd steal them
567 */
568 signr = __dequeue_signal(&tsk->pending, mask, info);
569 if (!signr) {
570 signr = __dequeue_signal(&tsk->signal->shared_pending,
571 mask, info);
572#ifdef CONFIG_POSIX_TIMERS
573 /*
574 * itimer signal ?
575 *
576 * itimers are process shared and we restart periodic
577 * itimers in the signal delivery path to prevent DoS
578 * attacks in the high resolution timer case. This is
579 * compliant with the old way of self-restarting
580 * itimers, as the SIGALRM is a legacy signal and only
581 * queued once. Changing the restart behaviour to
582 * restart the timer in the signal dequeue path is
583 * reducing the timer noise on heavy loaded !highres
584 * systems too.
585 */
586 if (unlikely(signr == SIGALRM)) {
587 struct hrtimer *tmr = &tsk->signal->real_timer;
588
589 if (!hrtimer_is_queued(tmr) &&
590 tsk->signal->it_real_incr != 0) {
591 hrtimer_forward(tmr, tmr->base->get_time(),
592 tsk->signal->it_real_incr);
593 hrtimer_restart(tmr);
594 }
595 }
596#endif
597 }
598
599 recalc_sigpending();
600 if (!signr)
601 return 0;
602
603 if (unlikely(sig_kernel_stop(signr))) {
604 /*
605 * Set a marker that we have dequeued a stop signal. Our
606 * caller might release the siglock and then the pending
607 * stop signal it is about to process is no longer in the
608 * pending bitmasks, but must still be cleared by a SIGCONT
609 * (and overruled by a SIGKILL). So those cases clear this
610 * shared flag after we've set it. Note that this flag may
611 * remain set after the signal we return is ignored or
612 * handled. That doesn't matter because its only purpose
613 * is to alert stop-signal processing code when another
614 * processor has come along and cleared the flag.
615 */
616 current->jobctl |= JOBCTL_STOP_DEQUEUED;
617 }
618#ifdef CONFIG_POSIX_TIMERS
619 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
620 /*
621 * Release the siglock to ensure proper locking order
622 * of timer locks outside of siglocks. Note, we leave
623 * irqs disabled here, since the posix-timers code is
624 * about to disable them again anyway.
625 */
626 spin_unlock(&tsk->sighand->siglock);
627 do_schedule_next_timer(info);
628 spin_lock(&tsk->sighand->siglock);
629 }
630#endif
631 return signr;
632}
633
634/*
635 * Tell a process that it has a new active signal..
636 *
637 * NOTE! we rely on the previous spin_lock to
638 * lock interrupts for us! We can only be called with
639 * "siglock" held, and the local interrupt must
640 * have been disabled when that got acquired!
641 *
642 * No need to set need_resched since signal event passing
643 * goes through ->blocked
644 */
645void signal_wake_up_state(struct task_struct *t, unsigned int state)
646{
647 set_tsk_thread_flag(t, TIF_SIGPENDING);
648 /*
649 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
650 * case. We don't check t->state here because there is a race with it
651 * executing another processor and just now entering stopped state.
652 * By using wake_up_state, we ensure the process will wake up and
653 * handle its death signal.
654 */
655 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
656 kick_process(t);
657}
658
659/*
660 * Remove signals in mask from the pending set and queue.
661 * Returns 1 if any signals were found.
662 *
663 * All callers must be holding the siglock.
664 */
665static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
666{
667 struct sigqueue *q, *n;
668 sigset_t m;
669
670 sigandsets(&m, mask, &s->signal);
671 if (sigisemptyset(&m))
672 return 0;
673
674 sigandnsets(&s->signal, &s->signal, mask);
675 list_for_each_entry_safe(q, n, &s->list, list) {
676 if (sigismember(mask, q->info.si_signo)) {
677 list_del_init(&q->list);
678 __sigqueue_free(q);
679 }
680 }
681 return 1;
682}
683
684static inline int is_si_special(const struct siginfo *info)
685{
686 return info <= SEND_SIG_FORCED;
687}
688
689static inline bool si_fromuser(const struct siginfo *info)
690{
691 return info == SEND_SIG_NOINFO ||
692 (!is_si_special(info) && SI_FROMUSER(info));
693}
694
695/*
696 * called with RCU read lock from check_kill_permission()
697 */
698static int kill_ok_by_cred(struct task_struct *t)
699{
700 const struct cred *cred = current_cred();
701 const struct cred *tcred = __task_cred(t);
702
703 if (uid_eq(cred->euid, tcred->suid) ||
704 uid_eq(cred->euid, tcred->uid) ||
705 uid_eq(cred->uid, tcred->suid) ||
706 uid_eq(cred->uid, tcred->uid))
707 return 1;
708
709 if (ns_capable(tcred->user_ns, CAP_KILL))
710 return 1;
711
712 return 0;
713}
714
715/*
716 * Bad permissions for sending the signal
717 * - the caller must hold the RCU read lock
718 */
719static int check_kill_permission(int sig, struct siginfo *info,
720 struct task_struct *t)
721{
722 struct pid *sid;
723 int error;
724
725 if (!valid_signal(sig))
726 return -EINVAL;
727
728 if (!si_fromuser(info))
729 return 0;
730
731 error = audit_signal_info(sig, t); /* Let audit system see the signal */
732 if (error)
733 return error;
734
735 if (!same_thread_group(current, t) &&
736 !kill_ok_by_cred(t)) {
737 switch (sig) {
738 case SIGCONT:
739 sid = task_session(t);
740 /*
741 * We don't return the error if sid == NULL. The
742 * task was unhashed, the caller must notice this.
743 */
744 if (!sid || sid == task_session(current))
745 break;
746 default:
747 return -EPERM;
748 }
749 }
750
751 return security_task_kill(t, info, sig, 0);
752}
753
754/**
755 * ptrace_trap_notify - schedule trap to notify ptracer
756 * @t: tracee wanting to notify tracer
757 *
758 * This function schedules sticky ptrace trap which is cleared on the next
759 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
760 * ptracer.
761 *
762 * If @t is running, STOP trap will be taken. If trapped for STOP and
763 * ptracer is listening for events, tracee is woken up so that it can
764 * re-trap for the new event. If trapped otherwise, STOP trap will be
765 * eventually taken without returning to userland after the existing traps
766 * are finished by PTRACE_CONT.
767 *
768 * CONTEXT:
769 * Must be called with @task->sighand->siglock held.
770 */
771static void ptrace_trap_notify(struct task_struct *t)
772{
773 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
774 assert_spin_locked(&t->sighand->siglock);
775
776 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
777 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
778}
779
780/*
781 * Handle magic process-wide effects of stop/continue signals. Unlike
782 * the signal actions, these happen immediately at signal-generation
783 * time regardless of blocking, ignoring, or handling. This does the
784 * actual continuing for SIGCONT, but not the actual stopping for stop
785 * signals. The process stop is done as a signal action for SIG_DFL.
786 *
787 * Returns true if the signal should be actually delivered, otherwise
788 * it should be dropped.
789 */
790static bool prepare_signal(int sig, struct task_struct *p, bool force)
791{
792 struct signal_struct *signal = p->signal;
793 struct task_struct *t;
794 sigset_t flush;
795
796 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
797 if (!(signal->flags & SIGNAL_GROUP_EXIT))
798 return sig == SIGKILL;
799 /*
800 * The process is in the middle of dying, nothing to do.
801 */
802 } else if (sig_kernel_stop(sig)) {
803 /*
804 * This is a stop signal. Remove SIGCONT from all queues.
805 */
806 siginitset(&flush, sigmask(SIGCONT));
807 flush_sigqueue_mask(&flush, &signal->shared_pending);
808 for_each_thread(p, t)
809 flush_sigqueue_mask(&flush, &t->pending);
810 } else if (sig == SIGCONT) {
811 unsigned int why;
812 /*
813 * Remove all stop signals from all queues, wake all threads.
814 */
815 siginitset(&flush, SIG_KERNEL_STOP_MASK);
816 flush_sigqueue_mask(&flush, &signal->shared_pending);
817 for_each_thread(p, t) {
818 flush_sigqueue_mask(&flush, &t->pending);
819 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
820 if (likely(!(t->ptrace & PT_SEIZED)))
821 wake_up_state(t, __TASK_STOPPED);
822 else
823 ptrace_trap_notify(t);
824 }
825
826 /*
827 * Notify the parent with CLD_CONTINUED if we were stopped.
828 *
829 * If we were in the middle of a group stop, we pretend it
830 * was already finished, and then continued. Since SIGCHLD
831 * doesn't queue we report only CLD_STOPPED, as if the next
832 * CLD_CONTINUED was dropped.
833 */
834 why = 0;
835 if (signal->flags & SIGNAL_STOP_STOPPED)
836 why |= SIGNAL_CLD_CONTINUED;
837 else if (signal->group_stop_count)
838 why |= SIGNAL_CLD_STOPPED;
839
840 if (why) {
841 /*
842 * The first thread which returns from do_signal_stop()
843 * will take ->siglock, notice SIGNAL_CLD_MASK, and
844 * notify its parent. See get_signal_to_deliver().
845 */
846 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
847 signal->group_stop_count = 0;
848 signal->group_exit_code = 0;
849 }
850 }
851
852 return !sig_ignored(p, sig, force);
853}
854
855/*
856 * Test if P wants to take SIG. After we've checked all threads with this,
857 * it's equivalent to finding no threads not blocking SIG. Any threads not
858 * blocking SIG were ruled out because they are not running and already
859 * have pending signals. Such threads will dequeue from the shared queue
860 * as soon as they're available, so putting the signal on the shared queue
861 * will be equivalent to sending it to one such thread.
862 */
863static inline int wants_signal(int sig, struct task_struct *p)
864{
865 if (sigismember(&p->blocked, sig))
866 return 0;
867 if (p->flags & PF_EXITING)
868 return 0;
869 if (sig == SIGKILL)
870 return 1;
871 if (task_is_stopped_or_traced(p))
872 return 0;
873 return task_curr(p) || !signal_pending(p);
874}
875
876static void complete_signal(int sig, struct task_struct *p, int group)
877{
878 struct signal_struct *signal = p->signal;
879 struct task_struct *t;
880
881 /*
882 * Now find a thread we can wake up to take the signal off the queue.
883 *
884 * If the main thread wants the signal, it gets first crack.
885 * Probably the least surprising to the average bear.
886 */
887 if (wants_signal(sig, p))
888 t = p;
889 else if (!group || thread_group_empty(p))
890 /*
891 * There is just one thread and it does not need to be woken.
892 * It will dequeue unblocked signals before it runs again.
893 */
894 return;
895 else {
896 /*
897 * Otherwise try to find a suitable thread.
898 */
899 t = signal->curr_target;
900 while (!wants_signal(sig, t)) {
901 t = next_thread(t);
902 if (t == signal->curr_target)
903 /*
904 * No thread needs to be woken.
905 * Any eligible threads will see
906 * the signal in the queue soon.
907 */
908 return;
909 }
910 signal->curr_target = t;
911 }
912
913 /*
914 * Found a killable thread. If the signal will be fatal,
915 * then start taking the whole group down immediately.
916 */
917 if (sig_fatal(p, sig) &&
918 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
919 !sigismember(&t->real_blocked, sig) &&
920 (sig == SIGKILL || !t->ptrace)) {
921 /*
922 * This signal will be fatal to the whole group.
923 */
924 if (!sig_kernel_coredump(sig)) {
925 /*
926 * Start a group exit and wake everybody up.
927 * This way we don't have other threads
928 * running and doing things after a slower
929 * thread has the fatal signal pending.
930 */
931 signal->flags = SIGNAL_GROUP_EXIT;
932 signal->group_exit_code = sig;
933 signal->group_stop_count = 0;
934 t = p;
935 do {
936 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
937 sigaddset(&t->pending.signal, SIGKILL);
938 signal_wake_up(t, 1);
939 } while_each_thread(p, t);
940 return;
941 }
942 }
943
944 /*
945 * The signal is already in the shared-pending queue.
946 * Tell the chosen thread to wake up and dequeue it.
947 */
948 signal_wake_up(t, sig == SIGKILL);
949 return;
950}
951
952static inline int legacy_queue(struct sigpending *signals, int sig)
953{
954 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
955}
956
957#ifdef CONFIG_USER_NS
958static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
959{
960 if (current_user_ns() == task_cred_xxx(t, user_ns))
961 return;
962
963 if (SI_FROMKERNEL(info))
964 return;
965
966 rcu_read_lock();
967 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
968 make_kuid(current_user_ns(), info->si_uid));
969 rcu_read_unlock();
970}
971#else
972static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
973{
974 return;
975}
976#endif
977
978static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
979 int group, int from_ancestor_ns)
980{
981 struct sigpending *pending;
982 struct sigqueue *q;
983 int override_rlimit;
984 int ret = 0, result;
985
986 assert_spin_locked(&t->sighand->siglock);
987
988 result = TRACE_SIGNAL_IGNORED;
989 if (!prepare_signal(sig, t,
990 from_ancestor_ns || (info == SEND_SIG_FORCED)))
991 goto ret;
992
993 pending = group ? &t->signal->shared_pending : &t->pending;
994 /*
995 * Short-circuit ignored signals and support queuing
996 * exactly one non-rt signal, so that we can get more
997 * detailed information about the cause of the signal.
998 */
999 result = TRACE_SIGNAL_ALREADY_PENDING;
1000 if (legacy_queue(pending, sig))
1001 goto ret;
1002
1003 result = TRACE_SIGNAL_DELIVERED;
1004 /*
1005 * fast-pathed signals for kernel-internal things like SIGSTOP
1006 * or SIGKILL.
1007 */
1008 if (info == SEND_SIG_FORCED)
1009 goto out_set;
1010
1011 /*
1012 * Real-time signals must be queued if sent by sigqueue, or
1013 * some other real-time mechanism. It is implementation
1014 * defined whether kill() does so. We attempt to do so, on
1015 * the principle of least surprise, but since kill is not
1016 * allowed to fail with EAGAIN when low on memory we just
1017 * make sure at least one signal gets delivered and don't
1018 * pass on the info struct.
1019 */
1020 if (sig < SIGRTMIN)
1021 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1022 else
1023 override_rlimit = 0;
1024
1025 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1026 override_rlimit);
1027 if (q) {
1028 list_add_tail(&q->list, &pending->list);
1029 switch ((unsigned long) info) {
1030 case (unsigned long) SEND_SIG_NOINFO:
1031 q->info.si_signo = sig;
1032 q->info.si_errno = 0;
1033 q->info.si_code = SI_USER;
1034 q->info.si_pid = task_tgid_nr_ns(current,
1035 task_active_pid_ns(t));
1036 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1037 break;
1038 case (unsigned long) SEND_SIG_PRIV:
1039 q->info.si_signo = sig;
1040 q->info.si_errno = 0;
1041 q->info.si_code = SI_KERNEL;
1042 q->info.si_pid = 0;
1043 q->info.si_uid = 0;
1044 break;
1045 default:
1046 copy_siginfo(&q->info, info);
1047 if (from_ancestor_ns)
1048 q->info.si_pid = 0;
1049 break;
1050 }
1051
1052 userns_fixup_signal_uid(&q->info, t);
1053
1054 } else if (!is_si_special(info)) {
1055 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1056 /*
1057 * Queue overflow, abort. We may abort if the
1058 * signal was rt and sent by user using something
1059 * other than kill().
1060 */
1061 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1062 ret = -EAGAIN;
1063 goto ret;
1064 } else {
1065 /*
1066 * This is a silent loss of information. We still
1067 * send the signal, but the *info bits are lost.
1068 */
1069 result = TRACE_SIGNAL_LOSE_INFO;
1070 }
1071 }
1072
1073out_set:
1074 signalfd_notify(t, sig);
1075 sigaddset(&pending->signal, sig);
1076 complete_signal(sig, t, group);
1077ret:
1078 trace_signal_generate(sig, info, t, group, result);
1079 return ret;
1080}
1081
1082static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1083 int group)
1084{
1085 int from_ancestor_ns = 0;
1086
1087#ifdef CONFIG_PID_NS
1088 from_ancestor_ns = si_fromuser(info) &&
1089 !task_pid_nr_ns(current, task_active_pid_ns(t));
1090#endif
1091
1092 return __send_signal(sig, info, t, group, from_ancestor_ns);
1093}
1094
1095static void print_fatal_signal(int signr)
1096{
1097 struct pt_regs *regs = signal_pt_regs();
1098 pr_info("potentially unexpected fatal signal %d.\n", signr);
1099
1100#if defined(__i386__) && !defined(__arch_um__)
1101 pr_info("code at %08lx: ", regs->ip);
1102 {
1103 int i;
1104 for (i = 0; i < 16; i++) {
1105 unsigned char insn;
1106
1107 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1108 break;
1109 pr_cont("%02x ", insn);
1110 }
1111 }
1112 pr_cont("\n");
1113#endif
1114 preempt_disable();
1115 show_regs(regs);
1116 preempt_enable();
1117}
1118
1119static int __init setup_print_fatal_signals(char *str)
1120{
1121 get_option (&str, &print_fatal_signals);
1122
1123 return 1;
1124}
1125
1126__setup("print-fatal-signals=", setup_print_fatal_signals);
1127
1128int
1129__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1130{
1131 return send_signal(sig, info, p, 1);
1132}
1133
1134static int
1135specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1136{
1137 return send_signal(sig, info, t, 0);
1138}
1139
1140int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1141 bool group)
1142{
1143 unsigned long flags;
1144 int ret = -ESRCH;
1145
1146 if (lock_task_sighand(p, &flags)) {
1147 ret = send_signal(sig, info, p, group);
1148 unlock_task_sighand(p, &flags);
1149 }
1150
1151 return ret;
1152}
1153
1154/*
1155 * Force a signal that the process can't ignore: if necessary
1156 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1157 *
1158 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1159 * since we do not want to have a signal handler that was blocked
1160 * be invoked when user space had explicitly blocked it.
1161 *
1162 * We don't want to have recursive SIGSEGV's etc, for example,
1163 * that is why we also clear SIGNAL_UNKILLABLE.
1164 */
1165int
1166force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1167{
1168 unsigned long int flags;
1169 int ret, blocked, ignored;
1170 struct k_sigaction *action;
1171
1172 spin_lock_irqsave(&t->sighand->siglock, flags);
1173 action = &t->sighand->action[sig-1];
1174 ignored = action->sa.sa_handler == SIG_IGN;
1175 blocked = sigismember(&t->blocked, sig);
1176 if (blocked || ignored) {
1177 action->sa.sa_handler = SIG_DFL;
1178 if (blocked) {
1179 sigdelset(&t->blocked, sig);
1180 recalc_sigpending_and_wake(t);
1181 }
1182 }
1183 if (action->sa.sa_handler == SIG_DFL)
1184 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1185 ret = specific_send_sig_info(sig, info, t);
1186 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1187
1188 return ret;
1189}
1190
1191/*
1192 * Nuke all other threads in the group.
1193 */
1194int zap_other_threads(struct task_struct *p)
1195{
1196 struct task_struct *t = p;
1197 int count = 0;
1198
1199 p->signal->group_stop_count = 0;
1200
1201 while_each_thread(p, t) {
1202 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1203 count++;
1204
1205 /* Don't bother with already dead threads */
1206 if (t->exit_state)
1207 continue;
1208 sigaddset(&t->pending.signal, SIGKILL);
1209 signal_wake_up(t, 1);
1210 }
1211
1212 return count;
1213}
1214
1215struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1216 unsigned long *flags)
1217{
1218 struct sighand_struct *sighand;
1219
1220 for (;;) {
1221 /*
1222 * Disable interrupts early to avoid deadlocks.
1223 * See rcu_read_unlock() comment header for details.
1224 */
1225 local_irq_save(*flags);
1226 rcu_read_lock();
1227 sighand = rcu_dereference(tsk->sighand);
1228 if (unlikely(sighand == NULL)) {
1229 rcu_read_unlock();
1230 local_irq_restore(*flags);
1231 break;
1232 }
1233 /*
1234 * This sighand can be already freed and even reused, but
1235 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1236 * initializes ->siglock: this slab can't go away, it has
1237 * the same object type, ->siglock can't be reinitialized.
1238 *
1239 * We need to ensure that tsk->sighand is still the same
1240 * after we take the lock, we can race with de_thread() or
1241 * __exit_signal(). In the latter case the next iteration
1242 * must see ->sighand == NULL.
1243 */
1244 spin_lock(&sighand->siglock);
1245 if (likely(sighand == tsk->sighand)) {
1246 rcu_read_unlock();
1247 break;
1248 }
1249 spin_unlock(&sighand->siglock);
1250 rcu_read_unlock();
1251 local_irq_restore(*flags);
1252 }
1253
1254 return sighand;
1255}
1256
1257/*
1258 * send signal info to all the members of a group
1259 */
1260int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1261{
1262 int ret;
1263
1264 rcu_read_lock();
1265 ret = check_kill_permission(sig, info, p);
1266 rcu_read_unlock();
1267
1268 if (!ret && sig)
1269 ret = do_send_sig_info(sig, info, p, true);
1270
1271 return ret;
1272}
1273
1274/*
1275 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1276 * control characters do (^C, ^Z etc)
1277 * - the caller must hold at least a readlock on tasklist_lock
1278 */
1279int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1280{
1281 struct task_struct *p = NULL;
1282 int retval, success;
1283
1284 success = 0;
1285 retval = -ESRCH;
1286 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1287 int err = group_send_sig_info(sig, info, p);
1288 success |= !err;
1289 retval = err;
1290 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1291 return success ? 0 : retval;
1292}
1293
1294int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1295{
1296 int error = -ESRCH;
1297 struct task_struct *p;
1298
1299 for (;;) {
1300 rcu_read_lock();
1301 p = pid_task(pid, PIDTYPE_PID);
1302 if (p)
1303 error = group_send_sig_info(sig, info, p);
1304 rcu_read_unlock();
1305 if (likely(!p || error != -ESRCH))
1306 return error;
1307
1308 /*
1309 * The task was unhashed in between, try again. If it
1310 * is dead, pid_task() will return NULL, if we race with
1311 * de_thread() it will find the new leader.
1312 */
1313 }
1314}
1315
1316int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1317{
1318 int error;
1319 rcu_read_lock();
1320 error = kill_pid_info(sig, info, find_vpid(pid));
1321 rcu_read_unlock();
1322 return error;
1323}
1324
1325static int kill_as_cred_perm(const struct cred *cred,
1326 struct task_struct *target)
1327{
1328 const struct cred *pcred = __task_cred(target);
1329 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1330 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1331 return 0;
1332 return 1;
1333}
1334
1335/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1336int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1337 const struct cred *cred, u32 secid)
1338{
1339 int ret = -EINVAL;
1340 struct task_struct *p;
1341 unsigned long flags;
1342
1343 if (!valid_signal(sig))
1344 return ret;
1345
1346 rcu_read_lock();
1347 p = pid_task(pid, PIDTYPE_PID);
1348 if (!p) {
1349 ret = -ESRCH;
1350 goto out_unlock;
1351 }
1352 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1353 ret = -EPERM;
1354 goto out_unlock;
1355 }
1356 ret = security_task_kill(p, info, sig, secid);
1357 if (ret)
1358 goto out_unlock;
1359
1360 if (sig) {
1361 if (lock_task_sighand(p, &flags)) {
1362 ret = __send_signal(sig, info, p, 1, 0);
1363 unlock_task_sighand(p, &flags);
1364 } else
1365 ret = -ESRCH;
1366 }
1367out_unlock:
1368 rcu_read_unlock();
1369 return ret;
1370}
1371EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1372
1373/*
1374 * kill_something_info() interprets pid in interesting ways just like kill(2).
1375 *
1376 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1377 * is probably wrong. Should make it like BSD or SYSV.
1378 */
1379
1380static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1381{
1382 int ret;
1383
1384 if (pid > 0) {
1385 rcu_read_lock();
1386 ret = kill_pid_info(sig, info, find_vpid(pid));
1387 rcu_read_unlock();
1388 return ret;
1389 }
1390
1391 read_lock(&tasklist_lock);
1392 if (pid != -1) {
1393 ret = __kill_pgrp_info(sig, info,
1394 pid ? find_vpid(-pid) : task_pgrp(current));
1395 } else {
1396 int retval = 0, count = 0;
1397 struct task_struct * p;
1398
1399 for_each_process(p) {
1400 if (task_pid_vnr(p) > 1 &&
1401 !same_thread_group(p, current)) {
1402 int err = group_send_sig_info(sig, info, p);
1403 ++count;
1404 if (err != -EPERM)
1405 retval = err;
1406 }
1407 }
1408 ret = count ? retval : -ESRCH;
1409 }
1410 read_unlock(&tasklist_lock);
1411
1412 return ret;
1413}
1414
1415/*
1416 * These are for backward compatibility with the rest of the kernel source.
1417 */
1418
1419int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1420{
1421 /*
1422 * Make sure legacy kernel users don't send in bad values
1423 * (normal paths check this in check_kill_permission).
1424 */
1425 if (!valid_signal(sig))
1426 return -EINVAL;
1427
1428 return do_send_sig_info(sig, info, p, false);
1429}
1430
1431#define __si_special(priv) \
1432 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1433
1434int
1435send_sig(int sig, struct task_struct *p, int priv)
1436{
1437 return send_sig_info(sig, __si_special(priv), p);
1438}
1439
1440void
1441force_sig(int sig, struct task_struct *p)
1442{
1443 force_sig_info(sig, SEND_SIG_PRIV, p);
1444}
1445
1446/*
1447 * When things go south during signal handling, we
1448 * will force a SIGSEGV. And if the signal that caused
1449 * the problem was already a SIGSEGV, we'll want to
1450 * make sure we don't even try to deliver the signal..
1451 */
1452int
1453force_sigsegv(int sig, struct task_struct *p)
1454{
1455 if (sig == SIGSEGV) {
1456 unsigned long flags;
1457 spin_lock_irqsave(&p->sighand->siglock, flags);
1458 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1459 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1460 }
1461 force_sig(SIGSEGV, p);
1462 return 0;
1463}
1464
1465int kill_pgrp(struct pid *pid, int sig, int priv)
1466{
1467 int ret;
1468
1469 read_lock(&tasklist_lock);
1470 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1471 read_unlock(&tasklist_lock);
1472
1473 return ret;
1474}
1475EXPORT_SYMBOL(kill_pgrp);
1476
1477int kill_pid(struct pid *pid, int sig, int priv)
1478{
1479 return kill_pid_info(sig, __si_special(priv), pid);
1480}
1481EXPORT_SYMBOL(kill_pid);
1482
1483/*
1484 * These functions support sending signals using preallocated sigqueue
1485 * structures. This is needed "because realtime applications cannot
1486 * afford to lose notifications of asynchronous events, like timer
1487 * expirations or I/O completions". In the case of POSIX Timers
1488 * we allocate the sigqueue structure from the timer_create. If this
1489 * allocation fails we are able to report the failure to the application
1490 * with an EAGAIN error.
1491 */
1492struct sigqueue *sigqueue_alloc(void)
1493{
1494 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1495
1496 if (q)
1497 q->flags |= SIGQUEUE_PREALLOC;
1498
1499 return q;
1500}
1501
1502void sigqueue_free(struct sigqueue *q)
1503{
1504 unsigned long flags;
1505 spinlock_t *lock = ¤t->sighand->siglock;
1506
1507 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1508 /*
1509 * We must hold ->siglock while testing q->list
1510 * to serialize with collect_signal() or with
1511 * __exit_signal()->flush_sigqueue().
1512 */
1513 spin_lock_irqsave(lock, flags);
1514 q->flags &= ~SIGQUEUE_PREALLOC;
1515 /*
1516 * If it is queued it will be freed when dequeued,
1517 * like the "regular" sigqueue.
1518 */
1519 if (!list_empty(&q->list))
1520 q = NULL;
1521 spin_unlock_irqrestore(lock, flags);
1522
1523 if (q)
1524 __sigqueue_free(q);
1525}
1526
1527int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1528{
1529 int sig = q->info.si_signo;
1530 struct sigpending *pending;
1531 unsigned long flags;
1532 int ret, result;
1533
1534 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1535
1536 ret = -1;
1537 if (!likely(lock_task_sighand(t, &flags)))
1538 goto ret;
1539
1540 ret = 1; /* the signal is ignored */
1541 result = TRACE_SIGNAL_IGNORED;
1542 if (!prepare_signal(sig, t, false))
1543 goto out;
1544
1545 ret = 0;
1546 if (unlikely(!list_empty(&q->list))) {
1547 /*
1548 * If an SI_TIMER entry is already queue just increment
1549 * the overrun count.
1550 */
1551 BUG_ON(q->info.si_code != SI_TIMER);
1552 q->info.si_overrun++;
1553 result = TRACE_SIGNAL_ALREADY_PENDING;
1554 goto out;
1555 }
1556 q->info.si_overrun = 0;
1557
1558 signalfd_notify(t, sig);
1559 pending = group ? &t->signal->shared_pending : &t->pending;
1560 list_add_tail(&q->list, &pending->list);
1561 sigaddset(&pending->signal, sig);
1562 complete_signal(sig, t, group);
1563 result = TRACE_SIGNAL_DELIVERED;
1564out:
1565 trace_signal_generate(sig, &q->info, t, group, result);
1566 unlock_task_sighand(t, &flags);
1567ret:
1568 return ret;
1569}
1570
1571/*
1572 * Let a parent know about the death of a child.
1573 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1574 *
1575 * Returns true if our parent ignored us and so we've switched to
1576 * self-reaping.
1577 */
1578bool do_notify_parent(struct task_struct *tsk, int sig)
1579{
1580 struct siginfo info;
1581 unsigned long flags;
1582 struct sighand_struct *psig;
1583 bool autoreap = false;
1584 cputime_t utime, stime;
1585
1586 BUG_ON(sig == -1);
1587
1588 /* do_notify_parent_cldstop should have been called instead. */
1589 BUG_ON(task_is_stopped_or_traced(tsk));
1590
1591 BUG_ON(!tsk->ptrace &&
1592 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1593
1594 if (sig != SIGCHLD) {
1595 /*
1596 * This is only possible if parent == real_parent.
1597 * Check if it has changed security domain.
1598 */
1599 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1600 sig = SIGCHLD;
1601 }
1602
1603 info.si_signo = sig;
1604 info.si_errno = 0;
1605 /*
1606 * We are under tasklist_lock here so our parent is tied to
1607 * us and cannot change.
1608 *
1609 * task_active_pid_ns will always return the same pid namespace
1610 * until a task passes through release_task.
1611 *
1612 * write_lock() currently calls preempt_disable() which is the
1613 * same as rcu_read_lock(), but according to Oleg, this is not
1614 * correct to rely on this
1615 */
1616 rcu_read_lock();
1617 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1618 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1619 task_uid(tsk));
1620 rcu_read_unlock();
1621
1622 task_cputime(tsk, &utime, &stime);
1623 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1624 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1625
1626 info.si_status = tsk->exit_code & 0x7f;
1627 if (tsk->exit_code & 0x80)
1628 info.si_code = CLD_DUMPED;
1629 else if (tsk->exit_code & 0x7f)
1630 info.si_code = CLD_KILLED;
1631 else {
1632 info.si_code = CLD_EXITED;
1633 info.si_status = tsk->exit_code >> 8;
1634 }
1635
1636 psig = tsk->parent->sighand;
1637 spin_lock_irqsave(&psig->siglock, flags);
1638 if (!tsk->ptrace && sig == SIGCHLD &&
1639 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1640 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1641 /*
1642 * We are exiting and our parent doesn't care. POSIX.1
1643 * defines special semantics for setting SIGCHLD to SIG_IGN
1644 * or setting the SA_NOCLDWAIT flag: we should be reaped
1645 * automatically and not left for our parent's wait4 call.
1646 * Rather than having the parent do it as a magic kind of
1647 * signal handler, we just set this to tell do_exit that we
1648 * can be cleaned up without becoming a zombie. Note that
1649 * we still call __wake_up_parent in this case, because a
1650 * blocked sys_wait4 might now return -ECHILD.
1651 *
1652 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1653 * is implementation-defined: we do (if you don't want
1654 * it, just use SIG_IGN instead).
1655 */
1656 autoreap = true;
1657 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1658 sig = 0;
1659 }
1660 if (valid_signal(sig) && sig)
1661 __group_send_sig_info(sig, &info, tsk->parent);
1662 __wake_up_parent(tsk, tsk->parent);
1663 spin_unlock_irqrestore(&psig->siglock, flags);
1664
1665 return autoreap;
1666}
1667
1668/**
1669 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1670 * @tsk: task reporting the state change
1671 * @for_ptracer: the notification is for ptracer
1672 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1673 *
1674 * Notify @tsk's parent that the stopped/continued state has changed. If
1675 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1676 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1677 *
1678 * CONTEXT:
1679 * Must be called with tasklist_lock at least read locked.
1680 */
1681static void do_notify_parent_cldstop(struct task_struct *tsk,
1682 bool for_ptracer, int why)
1683{
1684 struct siginfo info;
1685 unsigned long flags;
1686 struct task_struct *parent;
1687 struct sighand_struct *sighand;
1688 cputime_t utime, stime;
1689
1690 if (for_ptracer) {
1691 parent = tsk->parent;
1692 } else {
1693 tsk = tsk->group_leader;
1694 parent = tsk->real_parent;
1695 }
1696
1697 info.si_signo = SIGCHLD;
1698 info.si_errno = 0;
1699 /*
1700 * see comment in do_notify_parent() about the following 4 lines
1701 */
1702 rcu_read_lock();
1703 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1704 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1705 rcu_read_unlock();
1706
1707 task_cputime(tsk, &utime, &stime);
1708 info.si_utime = cputime_to_clock_t(utime);
1709 info.si_stime = cputime_to_clock_t(stime);
1710
1711 info.si_code = why;
1712 switch (why) {
1713 case CLD_CONTINUED:
1714 info.si_status = SIGCONT;
1715 break;
1716 case CLD_STOPPED:
1717 info.si_status = tsk->signal->group_exit_code & 0x7f;
1718 break;
1719 case CLD_TRAPPED:
1720 info.si_status = tsk->exit_code & 0x7f;
1721 break;
1722 default:
1723 BUG();
1724 }
1725
1726 sighand = parent->sighand;
1727 spin_lock_irqsave(&sighand->siglock, flags);
1728 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1729 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1730 __group_send_sig_info(SIGCHLD, &info, parent);
1731 /*
1732 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1733 */
1734 __wake_up_parent(tsk, parent);
1735 spin_unlock_irqrestore(&sighand->siglock, flags);
1736}
1737
1738static inline int may_ptrace_stop(void)
1739{
1740 if (!likely(current->ptrace))
1741 return 0;
1742 /*
1743 * Are we in the middle of do_coredump?
1744 * If so and our tracer is also part of the coredump stopping
1745 * is a deadlock situation, and pointless because our tracer
1746 * is dead so don't allow us to stop.
1747 * If SIGKILL was already sent before the caller unlocked
1748 * ->siglock we must see ->core_state != NULL. Otherwise it
1749 * is safe to enter schedule().
1750 *
1751 * This is almost outdated, a task with the pending SIGKILL can't
1752 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1753 * after SIGKILL was already dequeued.
1754 */
1755 if (unlikely(current->mm->core_state) &&
1756 unlikely(current->mm == current->parent->mm))
1757 return 0;
1758
1759 return 1;
1760}
1761
1762/*
1763 * Return non-zero if there is a SIGKILL that should be waking us up.
1764 * Called with the siglock held.
1765 */
1766static int sigkill_pending(struct task_struct *tsk)
1767{
1768 return sigismember(&tsk->pending.signal, SIGKILL) ||
1769 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1770}
1771
1772/*
1773 * This must be called with current->sighand->siglock held.
1774 *
1775 * This should be the path for all ptrace stops.
1776 * We always set current->last_siginfo while stopped here.
1777 * That makes it a way to test a stopped process for
1778 * being ptrace-stopped vs being job-control-stopped.
1779 *
1780 * If we actually decide not to stop at all because the tracer
1781 * is gone, we keep current->exit_code unless clear_code.
1782 */
1783static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1784 __releases(¤t->sighand->siglock)
1785 __acquires(¤t->sighand->siglock)
1786{
1787 bool gstop_done = false;
1788
1789 if (arch_ptrace_stop_needed(exit_code, info)) {
1790 /*
1791 * The arch code has something special to do before a
1792 * ptrace stop. This is allowed to block, e.g. for faults
1793 * on user stack pages. We can't keep the siglock while
1794 * calling arch_ptrace_stop, so we must release it now.
1795 * To preserve proper semantics, we must do this before
1796 * any signal bookkeeping like checking group_stop_count.
1797 * Meanwhile, a SIGKILL could come in before we retake the
1798 * siglock. That must prevent us from sleeping in TASK_TRACED.
1799 * So after regaining the lock, we must check for SIGKILL.
1800 */
1801 spin_unlock_irq(¤t->sighand->siglock);
1802 arch_ptrace_stop(exit_code, info);
1803 spin_lock_irq(¤t->sighand->siglock);
1804 if (sigkill_pending(current))
1805 return;
1806 }
1807
1808 /*
1809 * We're committing to trapping. TRACED should be visible before
1810 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1811 * Also, transition to TRACED and updates to ->jobctl should be
1812 * atomic with respect to siglock and should be done after the arch
1813 * hook as siglock is released and regrabbed across it.
1814 */
1815 set_current_state(TASK_TRACED);
1816
1817 current->last_siginfo = info;
1818 current->exit_code = exit_code;
1819
1820 /*
1821 * If @why is CLD_STOPPED, we're trapping to participate in a group
1822 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1823 * across siglock relocks since INTERRUPT was scheduled, PENDING
1824 * could be clear now. We act as if SIGCONT is received after
1825 * TASK_TRACED is entered - ignore it.
1826 */
1827 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1828 gstop_done = task_participate_group_stop(current);
1829
1830 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1831 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1832 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1833 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1834
1835 /* entering a trap, clear TRAPPING */
1836 task_clear_jobctl_trapping(current);
1837
1838 spin_unlock_irq(¤t->sighand->siglock);
1839 read_lock(&tasklist_lock);
1840 if (may_ptrace_stop()) {
1841 /*
1842 * Notify parents of the stop.
1843 *
1844 * While ptraced, there are two parents - the ptracer and
1845 * the real_parent of the group_leader. The ptracer should
1846 * know about every stop while the real parent is only
1847 * interested in the completion of group stop. The states
1848 * for the two don't interact with each other. Notify
1849 * separately unless they're gonna be duplicates.
1850 */
1851 do_notify_parent_cldstop(current, true, why);
1852 if (gstop_done && ptrace_reparented(current))
1853 do_notify_parent_cldstop(current, false, why);
1854
1855 /*
1856 * Don't want to allow preemption here, because
1857 * sys_ptrace() needs this task to be inactive.
1858 *
1859 * XXX: implement read_unlock_no_resched().
1860 */
1861 preempt_disable();
1862 read_unlock(&tasklist_lock);
1863 preempt_enable_no_resched();
1864 freezable_schedule();
1865 } else {
1866 /*
1867 * By the time we got the lock, our tracer went away.
1868 * Don't drop the lock yet, another tracer may come.
1869 *
1870 * If @gstop_done, the ptracer went away between group stop
1871 * completion and here. During detach, it would have set
1872 * JOBCTL_STOP_PENDING on us and we'll re-enter
1873 * TASK_STOPPED in do_signal_stop() on return, so notifying
1874 * the real parent of the group stop completion is enough.
1875 */
1876 if (gstop_done)
1877 do_notify_parent_cldstop(current, false, why);
1878
1879 /* tasklist protects us from ptrace_freeze_traced() */
1880 __set_current_state(TASK_RUNNING);
1881 if (clear_code)
1882 current->exit_code = 0;
1883 read_unlock(&tasklist_lock);
1884 }
1885
1886 /*
1887 * We are back. Now reacquire the siglock before touching
1888 * last_siginfo, so that we are sure to have synchronized with
1889 * any signal-sending on another CPU that wants to examine it.
1890 */
1891 spin_lock_irq(¤t->sighand->siglock);
1892 current->last_siginfo = NULL;
1893
1894 /* LISTENING can be set only during STOP traps, clear it */
1895 current->jobctl &= ~JOBCTL_LISTENING;
1896
1897 /*
1898 * Queued signals ignored us while we were stopped for tracing.
1899 * So check for any that we should take before resuming user mode.
1900 * This sets TIF_SIGPENDING, but never clears it.
1901 */
1902 recalc_sigpending_tsk(current);
1903}
1904
1905static void ptrace_do_notify(int signr, int exit_code, int why)
1906{
1907 siginfo_t info;
1908
1909 memset(&info, 0, sizeof info);
1910 info.si_signo = signr;
1911 info.si_code = exit_code;
1912 info.si_pid = task_pid_vnr(current);
1913 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1914
1915 /* Let the debugger run. */
1916 ptrace_stop(exit_code, why, 1, &info);
1917}
1918
1919void ptrace_notify(int exit_code)
1920{
1921 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1922 if (unlikely(current->task_works))
1923 task_work_run();
1924
1925 spin_lock_irq(¤t->sighand->siglock);
1926 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1927 spin_unlock_irq(¤t->sighand->siglock);
1928}
1929
1930/**
1931 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1932 * @signr: signr causing group stop if initiating
1933 *
1934 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1935 * and participate in it. If already set, participate in the existing
1936 * group stop. If participated in a group stop (and thus slept), %true is
1937 * returned with siglock released.
1938 *
1939 * If ptraced, this function doesn't handle stop itself. Instead,
1940 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1941 * untouched. The caller must ensure that INTERRUPT trap handling takes
1942 * places afterwards.
1943 *
1944 * CONTEXT:
1945 * Must be called with @current->sighand->siglock held, which is released
1946 * on %true return.
1947 *
1948 * RETURNS:
1949 * %false if group stop is already cancelled or ptrace trap is scheduled.
1950 * %true if participated in group stop.
1951 */
1952static bool do_signal_stop(int signr)
1953 __releases(¤t->sighand->siglock)
1954{
1955 struct signal_struct *sig = current->signal;
1956
1957 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1958 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1959 struct task_struct *t;
1960
1961 /* signr will be recorded in task->jobctl for retries */
1962 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1963
1964 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1965 unlikely(signal_group_exit(sig)))
1966 return false;
1967 /*
1968 * There is no group stop already in progress. We must
1969 * initiate one now.
1970 *
1971 * While ptraced, a task may be resumed while group stop is
1972 * still in effect and then receive a stop signal and
1973 * initiate another group stop. This deviates from the
1974 * usual behavior as two consecutive stop signals can't
1975 * cause two group stops when !ptraced. That is why we
1976 * also check !task_is_stopped(t) below.
1977 *
1978 * The condition can be distinguished by testing whether
1979 * SIGNAL_STOP_STOPPED is already set. Don't generate
1980 * group_exit_code in such case.
1981 *
1982 * This is not necessary for SIGNAL_STOP_CONTINUED because
1983 * an intervening stop signal is required to cause two
1984 * continued events regardless of ptrace.
1985 */
1986 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1987 sig->group_exit_code = signr;
1988
1989 sig->group_stop_count = 0;
1990
1991 if (task_set_jobctl_pending(current, signr | gstop))
1992 sig->group_stop_count++;
1993
1994 t = current;
1995 while_each_thread(current, t) {
1996 /*
1997 * Setting state to TASK_STOPPED for a group
1998 * stop is always done with the siglock held,
1999 * so this check has no races.
2000 */
2001 if (!task_is_stopped(t) &&
2002 task_set_jobctl_pending(t, signr | gstop)) {
2003 sig->group_stop_count++;
2004 if (likely(!(t->ptrace & PT_SEIZED)))
2005 signal_wake_up(t, 0);
2006 else
2007 ptrace_trap_notify(t);
2008 }
2009 }
2010 }
2011
2012 if (likely(!current->ptrace)) {
2013 int notify = 0;
2014
2015 /*
2016 * If there are no other threads in the group, or if there
2017 * is a group stop in progress and we are the last to stop,
2018 * report to the parent.
2019 */
2020 if (task_participate_group_stop(current))
2021 notify = CLD_STOPPED;
2022
2023 __set_current_state(TASK_STOPPED);
2024 spin_unlock_irq(¤t->sighand->siglock);
2025
2026 /*
2027 * Notify the parent of the group stop completion. Because
2028 * we're not holding either the siglock or tasklist_lock
2029 * here, ptracer may attach inbetween; however, this is for
2030 * group stop and should always be delivered to the real
2031 * parent of the group leader. The new ptracer will get
2032 * its notification when this task transitions into
2033 * TASK_TRACED.
2034 */
2035 if (notify) {
2036 read_lock(&tasklist_lock);
2037 do_notify_parent_cldstop(current, false, notify);
2038 read_unlock(&tasklist_lock);
2039 }
2040
2041 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2042 freezable_schedule();
2043 return true;
2044 } else {
2045 /*
2046 * While ptraced, group stop is handled by STOP trap.
2047 * Schedule it and let the caller deal with it.
2048 */
2049 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2050 return false;
2051 }
2052}
2053
2054/**
2055 * do_jobctl_trap - take care of ptrace jobctl traps
2056 *
2057 * When PT_SEIZED, it's used for both group stop and explicit
2058 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2059 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2060 * the stop signal; otherwise, %SIGTRAP.
2061 *
2062 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2063 * number as exit_code and no siginfo.
2064 *
2065 * CONTEXT:
2066 * Must be called with @current->sighand->siglock held, which may be
2067 * released and re-acquired before returning with intervening sleep.
2068 */
2069static void do_jobctl_trap(void)
2070{
2071 struct signal_struct *signal = current->signal;
2072 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2073
2074 if (current->ptrace & PT_SEIZED) {
2075 if (!signal->group_stop_count &&
2076 !(signal->flags & SIGNAL_STOP_STOPPED))
2077 signr = SIGTRAP;
2078 WARN_ON_ONCE(!signr);
2079 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2080 CLD_STOPPED);
2081 } else {
2082 WARN_ON_ONCE(!signr);
2083 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2084 current->exit_code = 0;
2085 }
2086}
2087
2088static int ptrace_signal(int signr, siginfo_t *info)
2089{
2090 ptrace_signal_deliver();
2091 /*
2092 * We do not check sig_kernel_stop(signr) but set this marker
2093 * unconditionally because we do not know whether debugger will
2094 * change signr. This flag has no meaning unless we are going
2095 * to stop after return from ptrace_stop(). In this case it will
2096 * be checked in do_signal_stop(), we should only stop if it was
2097 * not cleared by SIGCONT while we were sleeping. See also the
2098 * comment in dequeue_signal().
2099 */
2100 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2101 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2102
2103 /* We're back. Did the debugger cancel the sig? */
2104 signr = current->exit_code;
2105 if (signr == 0)
2106 return signr;
2107
2108 current->exit_code = 0;
2109
2110 /*
2111 * Update the siginfo structure if the signal has
2112 * changed. If the debugger wanted something
2113 * specific in the siginfo structure then it should
2114 * have updated *info via PTRACE_SETSIGINFO.
2115 */
2116 if (signr != info->si_signo) {
2117 info->si_signo = signr;
2118 info->si_errno = 0;
2119 info->si_code = SI_USER;
2120 rcu_read_lock();
2121 info->si_pid = task_pid_vnr(current->parent);
2122 info->si_uid = from_kuid_munged(current_user_ns(),
2123 task_uid(current->parent));
2124 rcu_read_unlock();
2125 }
2126
2127 /* If the (new) signal is now blocked, requeue it. */
2128 if (sigismember(¤t->blocked, signr)) {
2129 specific_send_sig_info(signr, info, current);
2130 signr = 0;
2131 }
2132
2133 return signr;
2134}
2135
2136int get_signal(struct ksignal *ksig)
2137{
2138 struct sighand_struct *sighand = current->sighand;
2139 struct signal_struct *signal = current->signal;
2140 int signr;
2141
2142 if (unlikely(current->task_works))
2143 task_work_run();
2144
2145 if (unlikely(uprobe_deny_signal()))
2146 return 0;
2147
2148 /*
2149 * Do this once, we can't return to user-mode if freezing() == T.
2150 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2151 * thus do not need another check after return.
2152 */
2153 try_to_freeze();
2154
2155relock:
2156 spin_lock_irq(&sighand->siglock);
2157 /*
2158 * Every stopped thread goes here after wakeup. Check to see if
2159 * we should notify the parent, prepare_signal(SIGCONT) encodes
2160 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2161 */
2162 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2163 int why;
2164
2165 if (signal->flags & SIGNAL_CLD_CONTINUED)
2166 why = CLD_CONTINUED;
2167 else
2168 why = CLD_STOPPED;
2169
2170 signal->flags &= ~SIGNAL_CLD_MASK;
2171
2172 spin_unlock_irq(&sighand->siglock);
2173
2174 /*
2175 * Notify the parent that we're continuing. This event is
2176 * always per-process and doesn't make whole lot of sense
2177 * for ptracers, who shouldn't consume the state via
2178 * wait(2) either, but, for backward compatibility, notify
2179 * the ptracer of the group leader too unless it's gonna be
2180 * a duplicate.
2181 */
2182 read_lock(&tasklist_lock);
2183 do_notify_parent_cldstop(current, false, why);
2184
2185 if (ptrace_reparented(current->group_leader))
2186 do_notify_parent_cldstop(current->group_leader,
2187 true, why);
2188 read_unlock(&tasklist_lock);
2189
2190 goto relock;
2191 }
2192
2193 for (;;) {
2194 struct k_sigaction *ka;
2195
2196 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2197 do_signal_stop(0))
2198 goto relock;
2199
2200 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2201 do_jobctl_trap();
2202 spin_unlock_irq(&sighand->siglock);
2203 goto relock;
2204 }
2205
2206 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2207
2208 if (!signr)
2209 break; /* will return 0 */
2210
2211 if (unlikely(current->ptrace) && signr != SIGKILL) {
2212 signr = ptrace_signal(signr, &ksig->info);
2213 if (!signr)
2214 continue;
2215 }
2216
2217 ka = &sighand->action[signr-1];
2218
2219 /* Trace actually delivered signals. */
2220 trace_signal_deliver(signr, &ksig->info, ka);
2221
2222 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2223 continue;
2224 if (ka->sa.sa_handler != SIG_DFL) {
2225 /* Run the handler. */
2226 ksig->ka = *ka;
2227
2228 if (ka->sa.sa_flags & SA_ONESHOT)
2229 ka->sa.sa_handler = SIG_DFL;
2230
2231 break; /* will return non-zero "signr" value */
2232 }
2233
2234 /*
2235 * Now we are doing the default action for this signal.
2236 */
2237 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2238 continue;
2239
2240 /*
2241 * Global init gets no signals it doesn't want.
2242 * Container-init gets no signals it doesn't want from same
2243 * container.
2244 *
2245 * Note that if global/container-init sees a sig_kernel_only()
2246 * signal here, the signal must have been generated internally
2247 * or must have come from an ancestor namespace. In either
2248 * case, the signal cannot be dropped.
2249 */
2250 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2251 !sig_kernel_only(signr))
2252 continue;
2253
2254 if (sig_kernel_stop(signr)) {
2255 /*
2256 * The default action is to stop all threads in
2257 * the thread group. The job control signals
2258 * do nothing in an orphaned pgrp, but SIGSTOP
2259 * always works. Note that siglock needs to be
2260 * dropped during the call to is_orphaned_pgrp()
2261 * because of lock ordering with tasklist_lock.
2262 * This allows an intervening SIGCONT to be posted.
2263 * We need to check for that and bail out if necessary.
2264 */
2265 if (signr != SIGSTOP) {
2266 spin_unlock_irq(&sighand->siglock);
2267
2268 /* signals can be posted during this window */
2269
2270 if (is_current_pgrp_orphaned())
2271 goto relock;
2272
2273 spin_lock_irq(&sighand->siglock);
2274 }
2275
2276 if (likely(do_signal_stop(ksig->info.si_signo))) {
2277 /* It released the siglock. */
2278 goto relock;
2279 }
2280
2281 /*
2282 * We didn't actually stop, due to a race
2283 * with SIGCONT or something like that.
2284 */
2285 continue;
2286 }
2287
2288 spin_unlock_irq(&sighand->siglock);
2289
2290 /*
2291 * Anything else is fatal, maybe with a core dump.
2292 */
2293 current->flags |= PF_SIGNALED;
2294
2295 if (sig_kernel_coredump(signr)) {
2296 if (print_fatal_signals)
2297 print_fatal_signal(ksig->info.si_signo);
2298 proc_coredump_connector(current);
2299 /*
2300 * If it was able to dump core, this kills all
2301 * other threads in the group and synchronizes with
2302 * their demise. If we lost the race with another
2303 * thread getting here, it set group_exit_code
2304 * first and our do_group_exit call below will use
2305 * that value and ignore the one we pass it.
2306 */
2307 do_coredump(&ksig->info);
2308 }
2309
2310 /*
2311 * Death signals, no core dump.
2312 */
2313 do_group_exit(ksig->info.si_signo);
2314 /* NOTREACHED */
2315 }
2316 spin_unlock_irq(&sighand->siglock);
2317
2318 ksig->sig = signr;
2319 return ksig->sig > 0;
2320}
2321
2322/**
2323 * signal_delivered -
2324 * @ksig: kernel signal struct
2325 * @stepping: nonzero if debugger single-step or block-step in use
2326 *
2327 * This function should be called when a signal has successfully been
2328 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2329 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2330 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2331 */
2332static void signal_delivered(struct ksignal *ksig, int stepping)
2333{
2334 sigset_t blocked;
2335
2336 /* A signal was successfully delivered, and the
2337 saved sigmask was stored on the signal frame,
2338 and will be restored by sigreturn. So we can
2339 simply clear the restore sigmask flag. */
2340 clear_restore_sigmask();
2341
2342 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2343 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2344 sigaddset(&blocked, ksig->sig);
2345 set_current_blocked(&blocked);
2346 tracehook_signal_handler(stepping);
2347}
2348
2349void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2350{
2351 if (failed)
2352 force_sigsegv(ksig->sig, current);
2353 else
2354 signal_delivered(ksig, stepping);
2355}
2356
2357/*
2358 * It could be that complete_signal() picked us to notify about the
2359 * group-wide signal. Other threads should be notified now to take
2360 * the shared signals in @which since we will not.
2361 */
2362static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2363{
2364 sigset_t retarget;
2365 struct task_struct *t;
2366
2367 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2368 if (sigisemptyset(&retarget))
2369 return;
2370
2371 t = tsk;
2372 while_each_thread(tsk, t) {
2373 if (t->flags & PF_EXITING)
2374 continue;
2375
2376 if (!has_pending_signals(&retarget, &t->blocked))
2377 continue;
2378 /* Remove the signals this thread can handle. */
2379 sigandsets(&retarget, &retarget, &t->blocked);
2380
2381 if (!signal_pending(t))
2382 signal_wake_up(t, 0);
2383
2384 if (sigisemptyset(&retarget))
2385 break;
2386 }
2387}
2388
2389void exit_signals(struct task_struct *tsk)
2390{
2391 int group_stop = 0;
2392 sigset_t unblocked;
2393
2394 /*
2395 * @tsk is about to have PF_EXITING set - lock out users which
2396 * expect stable threadgroup.
2397 */
2398 threadgroup_change_begin(tsk);
2399
2400 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2401 tsk->flags |= PF_EXITING;
2402 threadgroup_change_end(tsk);
2403 return;
2404 }
2405
2406 spin_lock_irq(&tsk->sighand->siglock);
2407 /*
2408 * From now this task is not visible for group-wide signals,
2409 * see wants_signal(), do_signal_stop().
2410 */
2411 tsk->flags |= PF_EXITING;
2412
2413 threadgroup_change_end(tsk);
2414
2415 if (!signal_pending(tsk))
2416 goto out;
2417
2418 unblocked = tsk->blocked;
2419 signotset(&unblocked);
2420 retarget_shared_pending(tsk, &unblocked);
2421
2422 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2423 task_participate_group_stop(tsk))
2424 group_stop = CLD_STOPPED;
2425out:
2426 spin_unlock_irq(&tsk->sighand->siglock);
2427
2428 /*
2429 * If group stop has completed, deliver the notification. This
2430 * should always go to the real parent of the group leader.
2431 */
2432 if (unlikely(group_stop)) {
2433 read_lock(&tasklist_lock);
2434 do_notify_parent_cldstop(tsk, false, group_stop);
2435 read_unlock(&tasklist_lock);
2436 }
2437}
2438
2439EXPORT_SYMBOL(recalc_sigpending);
2440EXPORT_SYMBOL_GPL(dequeue_signal);
2441EXPORT_SYMBOL(flush_signals);
2442EXPORT_SYMBOL(force_sig);
2443EXPORT_SYMBOL(send_sig);
2444EXPORT_SYMBOL(send_sig_info);
2445EXPORT_SYMBOL(sigprocmask);
2446
2447/*
2448 * System call entry points.
2449 */
2450
2451/**
2452 * sys_restart_syscall - restart a system call
2453 */
2454SYSCALL_DEFINE0(restart_syscall)
2455{
2456 struct restart_block *restart = ¤t->restart_block;
2457 return restart->fn(restart);
2458}
2459
2460long do_no_restart_syscall(struct restart_block *param)
2461{
2462 return -EINTR;
2463}
2464
2465static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2466{
2467 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2468 sigset_t newblocked;
2469 /* A set of now blocked but previously unblocked signals. */
2470 sigandnsets(&newblocked, newset, ¤t->blocked);
2471 retarget_shared_pending(tsk, &newblocked);
2472 }
2473 tsk->blocked = *newset;
2474 recalc_sigpending();
2475}
2476
2477/**
2478 * set_current_blocked - change current->blocked mask
2479 * @newset: new mask
2480 *
2481 * It is wrong to change ->blocked directly, this helper should be used
2482 * to ensure the process can't miss a shared signal we are going to block.
2483 */
2484void set_current_blocked(sigset_t *newset)
2485{
2486 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2487 __set_current_blocked(newset);
2488}
2489
2490void __set_current_blocked(const sigset_t *newset)
2491{
2492 struct task_struct *tsk = current;
2493
2494 /*
2495 * In case the signal mask hasn't changed, there is nothing we need
2496 * to do. The current->blocked shouldn't be modified by other task.
2497 */
2498 if (sigequalsets(&tsk->blocked, newset))
2499 return;
2500
2501 spin_lock_irq(&tsk->sighand->siglock);
2502 __set_task_blocked(tsk, newset);
2503 spin_unlock_irq(&tsk->sighand->siglock);
2504}
2505
2506/*
2507 * This is also useful for kernel threads that want to temporarily
2508 * (or permanently) block certain signals.
2509 *
2510 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2511 * interface happily blocks "unblockable" signals like SIGKILL
2512 * and friends.
2513 */
2514int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2515{
2516 struct task_struct *tsk = current;
2517 sigset_t newset;
2518
2519 /* Lockless, only current can change ->blocked, never from irq */
2520 if (oldset)
2521 *oldset = tsk->blocked;
2522
2523 switch (how) {
2524 case SIG_BLOCK:
2525 sigorsets(&newset, &tsk->blocked, set);
2526 break;
2527 case SIG_UNBLOCK:
2528 sigandnsets(&newset, &tsk->blocked, set);
2529 break;
2530 case SIG_SETMASK:
2531 newset = *set;
2532 break;
2533 default:
2534 return -EINVAL;
2535 }
2536
2537 __set_current_blocked(&newset);
2538 return 0;
2539}
2540
2541/**
2542 * sys_rt_sigprocmask - change the list of currently blocked signals
2543 * @how: whether to add, remove, or set signals
2544 * @nset: stores pending signals
2545 * @oset: previous value of signal mask if non-null
2546 * @sigsetsize: size of sigset_t type
2547 */
2548SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2549 sigset_t __user *, oset, size_t, sigsetsize)
2550{
2551 sigset_t old_set, new_set;
2552 int error;
2553
2554 /* XXX: Don't preclude handling different sized sigset_t's. */
2555 if (sigsetsize != sizeof(sigset_t))
2556 return -EINVAL;
2557
2558 old_set = current->blocked;
2559
2560 if (nset) {
2561 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2562 return -EFAULT;
2563 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2564
2565 error = sigprocmask(how, &new_set, NULL);
2566 if (error)
2567 return error;
2568 }
2569
2570 if (oset) {
2571 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2572 return -EFAULT;
2573 }
2574
2575 return 0;
2576}
2577
2578#ifdef CONFIG_COMPAT
2579COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2580 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2581{
2582#ifdef __BIG_ENDIAN
2583 sigset_t old_set = current->blocked;
2584
2585 /* XXX: Don't preclude handling different sized sigset_t's. */
2586 if (sigsetsize != sizeof(sigset_t))
2587 return -EINVAL;
2588
2589 if (nset) {
2590 compat_sigset_t new32;
2591 sigset_t new_set;
2592 int error;
2593 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2594 return -EFAULT;
2595
2596 sigset_from_compat(&new_set, &new32);
2597 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2598
2599 error = sigprocmask(how, &new_set, NULL);
2600 if (error)
2601 return error;
2602 }
2603 if (oset) {
2604 compat_sigset_t old32;
2605 sigset_to_compat(&old32, &old_set);
2606 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2607 return -EFAULT;
2608 }
2609 return 0;
2610#else
2611 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2612 (sigset_t __user *)oset, sigsetsize);
2613#endif
2614}
2615#endif
2616
2617static int do_sigpending(void *set, unsigned long sigsetsize)
2618{
2619 if (sigsetsize > sizeof(sigset_t))
2620 return -EINVAL;
2621
2622 spin_lock_irq(¤t->sighand->siglock);
2623 sigorsets(set, ¤t->pending.signal,
2624 ¤t->signal->shared_pending.signal);
2625 spin_unlock_irq(¤t->sighand->siglock);
2626
2627 /* Outside the lock because only this thread touches it. */
2628 sigandsets(set, ¤t->blocked, set);
2629 return 0;
2630}
2631
2632/**
2633 * sys_rt_sigpending - examine a pending signal that has been raised
2634 * while blocked
2635 * @uset: stores pending signals
2636 * @sigsetsize: size of sigset_t type or larger
2637 */
2638SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2639{
2640 sigset_t set;
2641 int err = do_sigpending(&set, sigsetsize);
2642 if (!err && copy_to_user(uset, &set, sigsetsize))
2643 err = -EFAULT;
2644 return err;
2645}
2646
2647#ifdef CONFIG_COMPAT
2648COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2649 compat_size_t, sigsetsize)
2650{
2651#ifdef __BIG_ENDIAN
2652 sigset_t set;
2653 int err = do_sigpending(&set, sigsetsize);
2654 if (!err) {
2655 compat_sigset_t set32;
2656 sigset_to_compat(&set32, &set);
2657 /* we can get here only if sigsetsize <= sizeof(set) */
2658 if (copy_to_user(uset, &set32, sigsetsize))
2659 err = -EFAULT;
2660 }
2661 return err;
2662#else
2663 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2664#endif
2665}
2666#endif
2667
2668#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2669
2670int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2671{
2672 int err;
2673
2674 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2675 return -EFAULT;
2676 if (from->si_code < 0)
2677 return __copy_to_user(to, from, sizeof(siginfo_t))
2678 ? -EFAULT : 0;
2679 /*
2680 * If you change siginfo_t structure, please be sure
2681 * this code is fixed accordingly.
2682 * Please remember to update the signalfd_copyinfo() function
2683 * inside fs/signalfd.c too, in case siginfo_t changes.
2684 * It should never copy any pad contained in the structure
2685 * to avoid security leaks, but must copy the generic
2686 * 3 ints plus the relevant union member.
2687 */
2688 err = __put_user(from->si_signo, &to->si_signo);
2689 err |= __put_user(from->si_errno, &to->si_errno);
2690 err |= __put_user((short)from->si_code, &to->si_code);
2691 switch (from->si_code & __SI_MASK) {
2692 case __SI_KILL:
2693 err |= __put_user(from->si_pid, &to->si_pid);
2694 err |= __put_user(from->si_uid, &to->si_uid);
2695 break;
2696 case __SI_TIMER:
2697 err |= __put_user(from->si_tid, &to->si_tid);
2698 err |= __put_user(from->si_overrun, &to->si_overrun);
2699 err |= __put_user(from->si_ptr, &to->si_ptr);
2700 break;
2701 case __SI_POLL:
2702 err |= __put_user(from->si_band, &to->si_band);
2703 err |= __put_user(from->si_fd, &to->si_fd);
2704 break;
2705 case __SI_FAULT:
2706 err |= __put_user(from->si_addr, &to->si_addr);
2707#ifdef __ARCH_SI_TRAPNO
2708 err |= __put_user(from->si_trapno, &to->si_trapno);
2709#endif
2710#ifdef BUS_MCEERR_AO
2711 /*
2712 * Other callers might not initialize the si_lsb field,
2713 * so check explicitly for the right codes here.
2714 */
2715 if (from->si_signo == SIGBUS &&
2716 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2717 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2718#endif
2719#ifdef SEGV_BNDERR
2720 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2721 err |= __put_user(from->si_lower, &to->si_lower);
2722 err |= __put_user(from->si_upper, &to->si_upper);
2723 }
2724#endif
2725#ifdef SEGV_PKUERR
2726 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2727 err |= __put_user(from->si_pkey, &to->si_pkey);
2728#endif
2729 break;
2730 case __SI_CHLD:
2731 err |= __put_user(from->si_pid, &to->si_pid);
2732 err |= __put_user(from->si_uid, &to->si_uid);
2733 err |= __put_user(from->si_status, &to->si_status);
2734 err |= __put_user(from->si_utime, &to->si_utime);
2735 err |= __put_user(from->si_stime, &to->si_stime);
2736 break;
2737 case __SI_RT: /* This is not generated by the kernel as of now. */
2738 case __SI_MESGQ: /* But this is */
2739 err |= __put_user(from->si_pid, &to->si_pid);
2740 err |= __put_user(from->si_uid, &to->si_uid);
2741 err |= __put_user(from->si_ptr, &to->si_ptr);
2742 break;
2743#ifdef __ARCH_SIGSYS
2744 case __SI_SYS:
2745 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2746 err |= __put_user(from->si_syscall, &to->si_syscall);
2747 err |= __put_user(from->si_arch, &to->si_arch);
2748 break;
2749#endif
2750 default: /* this is just in case for now ... */
2751 err |= __put_user(from->si_pid, &to->si_pid);
2752 err |= __put_user(from->si_uid, &to->si_uid);
2753 break;
2754 }
2755 return err;
2756}
2757
2758#endif
2759
2760/**
2761 * do_sigtimedwait - wait for queued signals specified in @which
2762 * @which: queued signals to wait for
2763 * @info: if non-null, the signal's siginfo is returned here
2764 * @ts: upper bound on process time suspension
2765 */
2766int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2767 const struct timespec *ts)
2768{
2769 ktime_t *to = NULL, timeout = KTIME_MAX;
2770 struct task_struct *tsk = current;
2771 sigset_t mask = *which;
2772 int sig, ret = 0;
2773
2774 if (ts) {
2775 if (!timespec_valid(ts))
2776 return -EINVAL;
2777 timeout = timespec_to_ktime(*ts);
2778 to = &timeout;
2779 }
2780
2781 /*
2782 * Invert the set of allowed signals to get those we want to block.
2783 */
2784 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2785 signotset(&mask);
2786
2787 spin_lock_irq(&tsk->sighand->siglock);
2788 sig = dequeue_signal(tsk, &mask, info);
2789 if (!sig && timeout) {
2790 /*
2791 * None ready, temporarily unblock those we're interested
2792 * while we are sleeping in so that we'll be awakened when
2793 * they arrive. Unblocking is always fine, we can avoid
2794 * set_current_blocked().
2795 */
2796 tsk->real_blocked = tsk->blocked;
2797 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2798 recalc_sigpending();
2799 spin_unlock_irq(&tsk->sighand->siglock);
2800
2801 __set_current_state(TASK_INTERRUPTIBLE);
2802 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
2803 HRTIMER_MODE_REL);
2804 spin_lock_irq(&tsk->sighand->siglock);
2805 __set_task_blocked(tsk, &tsk->real_blocked);
2806 sigemptyset(&tsk->real_blocked);
2807 sig = dequeue_signal(tsk, &mask, info);
2808 }
2809 spin_unlock_irq(&tsk->sighand->siglock);
2810
2811 if (sig)
2812 return sig;
2813 return ret ? -EINTR : -EAGAIN;
2814}
2815
2816/**
2817 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2818 * in @uthese
2819 * @uthese: queued signals to wait for
2820 * @uinfo: if non-null, the signal's siginfo is returned here
2821 * @uts: upper bound on process time suspension
2822 * @sigsetsize: size of sigset_t type
2823 */
2824SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2825 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2826 size_t, sigsetsize)
2827{
2828 sigset_t these;
2829 struct timespec ts;
2830 siginfo_t info;
2831 int ret;
2832
2833 /* XXX: Don't preclude handling different sized sigset_t's. */
2834 if (sigsetsize != sizeof(sigset_t))
2835 return -EINVAL;
2836
2837 if (copy_from_user(&these, uthese, sizeof(these)))
2838 return -EFAULT;
2839
2840 if (uts) {
2841 if (copy_from_user(&ts, uts, sizeof(ts)))
2842 return -EFAULT;
2843 }
2844
2845 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2846
2847 if (ret > 0 && uinfo) {
2848 if (copy_siginfo_to_user(uinfo, &info))
2849 ret = -EFAULT;
2850 }
2851
2852 return ret;
2853}
2854
2855/**
2856 * sys_kill - send a signal to a process
2857 * @pid: the PID of the process
2858 * @sig: signal to be sent
2859 */
2860SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2861{
2862 struct siginfo info;
2863
2864 info.si_signo = sig;
2865 info.si_errno = 0;
2866 info.si_code = SI_USER;
2867 info.si_pid = task_tgid_vnr(current);
2868 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2869
2870 return kill_something_info(sig, &info, pid);
2871}
2872
2873static int
2874do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2875{
2876 struct task_struct *p;
2877 int error = -ESRCH;
2878
2879 rcu_read_lock();
2880 p = find_task_by_vpid(pid);
2881 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2882 error = check_kill_permission(sig, info, p);
2883 /*
2884 * The null signal is a permissions and process existence
2885 * probe. No signal is actually delivered.
2886 */
2887 if (!error && sig) {
2888 error = do_send_sig_info(sig, info, p, false);
2889 /*
2890 * If lock_task_sighand() failed we pretend the task
2891 * dies after receiving the signal. The window is tiny,
2892 * and the signal is private anyway.
2893 */
2894 if (unlikely(error == -ESRCH))
2895 error = 0;
2896 }
2897 }
2898 rcu_read_unlock();
2899
2900 return error;
2901}
2902
2903static int do_tkill(pid_t tgid, pid_t pid, int sig)
2904{
2905 struct siginfo info = {};
2906
2907 info.si_signo = sig;
2908 info.si_errno = 0;
2909 info.si_code = SI_TKILL;
2910 info.si_pid = task_tgid_vnr(current);
2911 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2912
2913 return do_send_specific(tgid, pid, sig, &info);
2914}
2915
2916/**
2917 * sys_tgkill - send signal to one specific thread
2918 * @tgid: the thread group ID of the thread
2919 * @pid: the PID of the thread
2920 * @sig: signal to be sent
2921 *
2922 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2923 * exists but it's not belonging to the target process anymore. This
2924 * method solves the problem of threads exiting and PIDs getting reused.
2925 */
2926SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2927{
2928 /* This is only valid for single tasks */
2929 if (pid <= 0 || tgid <= 0)
2930 return -EINVAL;
2931
2932 return do_tkill(tgid, pid, sig);
2933}
2934
2935/**
2936 * sys_tkill - send signal to one specific task
2937 * @pid: the PID of the task
2938 * @sig: signal to be sent
2939 *
2940 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2941 */
2942SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2943{
2944 /* This is only valid for single tasks */
2945 if (pid <= 0)
2946 return -EINVAL;
2947
2948 return do_tkill(0, pid, sig);
2949}
2950
2951static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2952{
2953 /* Not even root can pretend to send signals from the kernel.
2954 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2955 */
2956 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2957 (task_pid_vnr(current) != pid))
2958 return -EPERM;
2959
2960 info->si_signo = sig;
2961
2962 /* POSIX.1b doesn't mention process groups. */
2963 return kill_proc_info(sig, info, pid);
2964}
2965
2966/**
2967 * sys_rt_sigqueueinfo - send signal information to a signal
2968 * @pid: the PID of the thread
2969 * @sig: signal to be sent
2970 * @uinfo: signal info to be sent
2971 */
2972SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2973 siginfo_t __user *, uinfo)
2974{
2975 siginfo_t info;
2976 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2977 return -EFAULT;
2978 return do_rt_sigqueueinfo(pid, sig, &info);
2979}
2980
2981#ifdef CONFIG_COMPAT
2982COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
2983 compat_pid_t, pid,
2984 int, sig,
2985 struct compat_siginfo __user *, uinfo)
2986{
2987 siginfo_t info = {};
2988 int ret = copy_siginfo_from_user32(&info, uinfo);
2989 if (unlikely(ret))
2990 return ret;
2991 return do_rt_sigqueueinfo(pid, sig, &info);
2992}
2993#endif
2994
2995static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2996{
2997 /* This is only valid for single tasks */
2998 if (pid <= 0 || tgid <= 0)
2999 return -EINVAL;
3000
3001 /* Not even root can pretend to send signals from the kernel.
3002 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3003 */
3004 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3005 (task_pid_vnr(current) != pid))
3006 return -EPERM;
3007
3008 info->si_signo = sig;
3009
3010 return do_send_specific(tgid, pid, sig, info);
3011}
3012
3013SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3014 siginfo_t __user *, uinfo)
3015{
3016 siginfo_t info;
3017
3018 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3019 return -EFAULT;
3020
3021 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3022}
3023
3024#ifdef CONFIG_COMPAT
3025COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3026 compat_pid_t, tgid,
3027 compat_pid_t, pid,
3028 int, sig,
3029 struct compat_siginfo __user *, uinfo)
3030{
3031 siginfo_t info = {};
3032
3033 if (copy_siginfo_from_user32(&info, uinfo))
3034 return -EFAULT;
3035 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3036}
3037#endif
3038
3039/*
3040 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3041 */
3042void kernel_sigaction(int sig, __sighandler_t action)
3043{
3044 spin_lock_irq(¤t->sighand->siglock);
3045 current->sighand->action[sig - 1].sa.sa_handler = action;
3046 if (action == SIG_IGN) {
3047 sigset_t mask;
3048
3049 sigemptyset(&mask);
3050 sigaddset(&mask, sig);
3051
3052 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3053 flush_sigqueue_mask(&mask, ¤t->pending);
3054 recalc_sigpending();
3055 }
3056 spin_unlock_irq(¤t->sighand->siglock);
3057}
3058EXPORT_SYMBOL(kernel_sigaction);
3059
3060void __weak sigaction_compat_abi(struct k_sigaction *act,
3061 struct k_sigaction *oact)
3062{
3063}
3064
3065int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3066{
3067 struct task_struct *p = current, *t;
3068 struct k_sigaction *k;
3069 sigset_t mask;
3070
3071 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3072 return -EINVAL;
3073
3074 k = &p->sighand->action[sig-1];
3075
3076 spin_lock_irq(&p->sighand->siglock);
3077 if (oact)
3078 *oact = *k;
3079
3080 sigaction_compat_abi(act, oact);
3081
3082 if (act) {
3083 sigdelsetmask(&act->sa.sa_mask,
3084 sigmask(SIGKILL) | sigmask(SIGSTOP));
3085 *k = *act;
3086 /*
3087 * POSIX 3.3.1.3:
3088 * "Setting a signal action to SIG_IGN for a signal that is
3089 * pending shall cause the pending signal to be discarded,
3090 * whether or not it is blocked."
3091 *
3092 * "Setting a signal action to SIG_DFL for a signal that is
3093 * pending and whose default action is to ignore the signal
3094 * (for example, SIGCHLD), shall cause the pending signal to
3095 * be discarded, whether or not it is blocked"
3096 */
3097 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3098 sigemptyset(&mask);
3099 sigaddset(&mask, sig);
3100 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3101 for_each_thread(p, t)
3102 flush_sigqueue_mask(&mask, &t->pending);
3103 }
3104 }
3105
3106 spin_unlock_irq(&p->sighand->siglock);
3107 return 0;
3108}
3109
3110static int
3111do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3112{
3113 stack_t oss;
3114 int error;
3115
3116 oss.ss_sp = (void __user *) current->sas_ss_sp;
3117 oss.ss_size = current->sas_ss_size;
3118 oss.ss_flags = sas_ss_flags(sp) |
3119 (current->sas_ss_flags & SS_FLAG_BITS);
3120
3121 if (uss) {
3122 void __user *ss_sp;
3123 size_t ss_size;
3124 unsigned ss_flags;
3125 int ss_mode;
3126
3127 error = -EFAULT;
3128 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3129 goto out;
3130 error = __get_user(ss_sp, &uss->ss_sp) |
3131 __get_user(ss_flags, &uss->ss_flags) |
3132 __get_user(ss_size, &uss->ss_size);
3133 if (error)
3134 goto out;
3135
3136 error = -EPERM;
3137 if (on_sig_stack(sp))
3138 goto out;
3139
3140 ss_mode = ss_flags & ~SS_FLAG_BITS;
3141 error = -EINVAL;
3142 if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3143 ss_mode != 0)
3144 goto out;
3145
3146 if (ss_mode == SS_DISABLE) {
3147 ss_size = 0;
3148 ss_sp = NULL;
3149 } else {
3150 error = -ENOMEM;
3151 if (ss_size < MINSIGSTKSZ)
3152 goto out;
3153 }
3154
3155 current->sas_ss_sp = (unsigned long) ss_sp;
3156 current->sas_ss_size = ss_size;
3157 current->sas_ss_flags = ss_flags;
3158 }
3159
3160 error = 0;
3161 if (uoss) {
3162 error = -EFAULT;
3163 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3164 goto out;
3165 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3166 __put_user(oss.ss_size, &uoss->ss_size) |
3167 __put_user(oss.ss_flags, &uoss->ss_flags);
3168 }
3169
3170out:
3171 return error;
3172}
3173SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3174{
3175 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3176}
3177
3178int restore_altstack(const stack_t __user *uss)
3179{
3180 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3181 /* squash all but EFAULT for now */
3182 return err == -EFAULT ? err : 0;
3183}
3184
3185int __save_altstack(stack_t __user *uss, unsigned long sp)
3186{
3187 struct task_struct *t = current;
3188 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3189 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3190 __put_user(t->sas_ss_size, &uss->ss_size);
3191 if (err)
3192 return err;
3193 if (t->sas_ss_flags & SS_AUTODISARM)
3194 sas_ss_reset(t);
3195 return 0;
3196}
3197
3198#ifdef CONFIG_COMPAT
3199COMPAT_SYSCALL_DEFINE2(sigaltstack,
3200 const compat_stack_t __user *, uss_ptr,
3201 compat_stack_t __user *, uoss_ptr)
3202{
3203 stack_t uss, uoss;
3204 int ret;
3205 mm_segment_t seg;
3206
3207 if (uss_ptr) {
3208 compat_stack_t uss32;
3209
3210 memset(&uss, 0, sizeof(stack_t));
3211 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3212 return -EFAULT;
3213 uss.ss_sp = compat_ptr(uss32.ss_sp);
3214 uss.ss_flags = uss32.ss_flags;
3215 uss.ss_size = uss32.ss_size;
3216 }
3217 seg = get_fs();
3218 set_fs(KERNEL_DS);
3219 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3220 (stack_t __force __user *) &uoss,
3221 compat_user_stack_pointer());
3222 set_fs(seg);
3223 if (ret >= 0 && uoss_ptr) {
3224 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3225 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3226 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3227 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3228 ret = -EFAULT;
3229 }
3230 return ret;
3231}
3232
3233int compat_restore_altstack(const compat_stack_t __user *uss)
3234{
3235 int err = compat_sys_sigaltstack(uss, NULL);
3236 /* squash all but -EFAULT for now */
3237 return err == -EFAULT ? err : 0;
3238}
3239
3240int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3241{
3242 int err;
3243 struct task_struct *t = current;
3244 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3245 &uss->ss_sp) |
3246 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3247 __put_user(t->sas_ss_size, &uss->ss_size);
3248 if (err)
3249 return err;
3250 if (t->sas_ss_flags & SS_AUTODISARM)
3251 sas_ss_reset(t);
3252 return 0;
3253}
3254#endif
3255
3256#ifdef __ARCH_WANT_SYS_SIGPENDING
3257
3258/**
3259 * sys_sigpending - examine pending signals
3260 * @set: where mask of pending signal is returned
3261 */
3262SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3263{
3264 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3265}
3266
3267#endif
3268
3269#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3270/**
3271 * sys_sigprocmask - examine and change blocked signals
3272 * @how: whether to add, remove, or set signals
3273 * @nset: signals to add or remove (if non-null)
3274 * @oset: previous value of signal mask if non-null
3275 *
3276 * Some platforms have their own version with special arguments;
3277 * others support only sys_rt_sigprocmask.
3278 */
3279
3280SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3281 old_sigset_t __user *, oset)
3282{
3283 old_sigset_t old_set, new_set;
3284 sigset_t new_blocked;
3285
3286 old_set = current->blocked.sig[0];
3287
3288 if (nset) {
3289 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3290 return -EFAULT;
3291
3292 new_blocked = current->blocked;
3293
3294 switch (how) {
3295 case SIG_BLOCK:
3296 sigaddsetmask(&new_blocked, new_set);
3297 break;
3298 case SIG_UNBLOCK:
3299 sigdelsetmask(&new_blocked, new_set);
3300 break;
3301 case SIG_SETMASK:
3302 new_blocked.sig[0] = new_set;
3303 break;
3304 default:
3305 return -EINVAL;
3306 }
3307
3308 set_current_blocked(&new_blocked);
3309 }
3310
3311 if (oset) {
3312 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3313 return -EFAULT;
3314 }
3315
3316 return 0;
3317}
3318#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3319
3320#ifndef CONFIG_ODD_RT_SIGACTION
3321/**
3322 * sys_rt_sigaction - alter an action taken by a process
3323 * @sig: signal to be sent
3324 * @act: new sigaction
3325 * @oact: used to save the previous sigaction
3326 * @sigsetsize: size of sigset_t type
3327 */
3328SYSCALL_DEFINE4(rt_sigaction, int, sig,
3329 const struct sigaction __user *, act,
3330 struct sigaction __user *, oact,
3331 size_t, sigsetsize)
3332{
3333 struct k_sigaction new_sa, old_sa;
3334 int ret = -EINVAL;
3335
3336 /* XXX: Don't preclude handling different sized sigset_t's. */
3337 if (sigsetsize != sizeof(sigset_t))
3338 goto out;
3339
3340 if (act) {
3341 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3342 return -EFAULT;
3343 }
3344
3345 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3346
3347 if (!ret && oact) {
3348 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3349 return -EFAULT;
3350 }
3351out:
3352 return ret;
3353}
3354#ifdef CONFIG_COMPAT
3355COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3356 const struct compat_sigaction __user *, act,
3357 struct compat_sigaction __user *, oact,
3358 compat_size_t, sigsetsize)
3359{
3360 struct k_sigaction new_ka, old_ka;
3361 compat_sigset_t mask;
3362#ifdef __ARCH_HAS_SA_RESTORER
3363 compat_uptr_t restorer;
3364#endif
3365 int ret;
3366
3367 /* XXX: Don't preclude handling different sized sigset_t's. */
3368 if (sigsetsize != sizeof(compat_sigset_t))
3369 return -EINVAL;
3370
3371 if (act) {
3372 compat_uptr_t handler;
3373 ret = get_user(handler, &act->sa_handler);
3374 new_ka.sa.sa_handler = compat_ptr(handler);
3375#ifdef __ARCH_HAS_SA_RESTORER
3376 ret |= get_user(restorer, &act->sa_restorer);
3377 new_ka.sa.sa_restorer = compat_ptr(restorer);
3378#endif
3379 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3380 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3381 if (ret)
3382 return -EFAULT;
3383 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3384 }
3385
3386 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3387 if (!ret && oact) {
3388 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3389 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3390 &oact->sa_handler);
3391 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3392 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3393#ifdef __ARCH_HAS_SA_RESTORER
3394 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3395 &oact->sa_restorer);
3396#endif
3397 }
3398 return ret;
3399}
3400#endif
3401#endif /* !CONFIG_ODD_RT_SIGACTION */
3402
3403#ifdef CONFIG_OLD_SIGACTION
3404SYSCALL_DEFINE3(sigaction, int, sig,
3405 const struct old_sigaction __user *, act,
3406 struct old_sigaction __user *, oact)
3407{
3408 struct k_sigaction new_ka, old_ka;
3409 int ret;
3410
3411 if (act) {
3412 old_sigset_t mask;
3413 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3414 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3415 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3416 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3417 __get_user(mask, &act->sa_mask))
3418 return -EFAULT;
3419#ifdef __ARCH_HAS_KA_RESTORER
3420 new_ka.ka_restorer = NULL;
3421#endif
3422 siginitset(&new_ka.sa.sa_mask, mask);
3423 }
3424
3425 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3426
3427 if (!ret && oact) {
3428 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3429 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3430 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3431 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3432 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3433 return -EFAULT;
3434 }
3435
3436 return ret;
3437}
3438#endif
3439#ifdef CONFIG_COMPAT_OLD_SIGACTION
3440COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3441 const struct compat_old_sigaction __user *, act,
3442 struct compat_old_sigaction __user *, oact)
3443{
3444 struct k_sigaction new_ka, old_ka;
3445 int ret;
3446 compat_old_sigset_t mask;
3447 compat_uptr_t handler, restorer;
3448
3449 if (act) {
3450 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3451 __get_user(handler, &act->sa_handler) ||
3452 __get_user(restorer, &act->sa_restorer) ||
3453 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3454 __get_user(mask, &act->sa_mask))
3455 return -EFAULT;
3456
3457#ifdef __ARCH_HAS_KA_RESTORER
3458 new_ka.ka_restorer = NULL;
3459#endif
3460 new_ka.sa.sa_handler = compat_ptr(handler);
3461 new_ka.sa.sa_restorer = compat_ptr(restorer);
3462 siginitset(&new_ka.sa.sa_mask, mask);
3463 }
3464
3465 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3466
3467 if (!ret && oact) {
3468 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3469 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3470 &oact->sa_handler) ||
3471 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3472 &oact->sa_restorer) ||
3473 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3474 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3475 return -EFAULT;
3476 }
3477 return ret;
3478}
3479#endif
3480
3481#ifdef CONFIG_SGETMASK_SYSCALL
3482
3483/*
3484 * For backwards compatibility. Functionality superseded by sigprocmask.
3485 */
3486SYSCALL_DEFINE0(sgetmask)
3487{
3488 /* SMP safe */
3489 return current->blocked.sig[0];
3490}
3491
3492SYSCALL_DEFINE1(ssetmask, int, newmask)
3493{
3494 int old = current->blocked.sig[0];
3495 sigset_t newset;
3496
3497 siginitset(&newset, newmask);
3498 set_current_blocked(&newset);
3499
3500 return old;
3501}
3502#endif /* CONFIG_SGETMASK_SYSCALL */
3503
3504#ifdef __ARCH_WANT_SYS_SIGNAL
3505/*
3506 * For backwards compatibility. Functionality superseded by sigaction.
3507 */
3508SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3509{
3510 struct k_sigaction new_sa, old_sa;
3511 int ret;
3512
3513 new_sa.sa.sa_handler = handler;
3514 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3515 sigemptyset(&new_sa.sa.sa_mask);
3516
3517 ret = do_sigaction(sig, &new_sa, &old_sa);
3518
3519 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3520}
3521#endif /* __ARCH_WANT_SYS_SIGNAL */
3522
3523#ifdef __ARCH_WANT_SYS_PAUSE
3524
3525SYSCALL_DEFINE0(pause)
3526{
3527 while (!signal_pending(current)) {
3528 __set_current_state(TASK_INTERRUPTIBLE);
3529 schedule();
3530 }
3531 return -ERESTARTNOHAND;
3532}
3533
3534#endif
3535
3536static int sigsuspend(sigset_t *set)
3537{
3538 current->saved_sigmask = current->blocked;
3539 set_current_blocked(set);
3540
3541 while (!signal_pending(current)) {
3542 __set_current_state(TASK_INTERRUPTIBLE);
3543 schedule();
3544 }
3545 set_restore_sigmask();
3546 return -ERESTARTNOHAND;
3547}
3548
3549/**
3550 * sys_rt_sigsuspend - replace the signal mask for a value with the
3551 * @unewset value until a signal is received
3552 * @unewset: new signal mask value
3553 * @sigsetsize: size of sigset_t type
3554 */
3555SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3556{
3557 sigset_t newset;
3558
3559 /* XXX: Don't preclude handling different sized sigset_t's. */
3560 if (sigsetsize != sizeof(sigset_t))
3561 return -EINVAL;
3562
3563 if (copy_from_user(&newset, unewset, sizeof(newset)))
3564 return -EFAULT;
3565 return sigsuspend(&newset);
3566}
3567
3568#ifdef CONFIG_COMPAT
3569COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3570{
3571#ifdef __BIG_ENDIAN
3572 sigset_t newset;
3573 compat_sigset_t newset32;
3574
3575 /* XXX: Don't preclude handling different sized sigset_t's. */
3576 if (sigsetsize != sizeof(sigset_t))
3577 return -EINVAL;
3578
3579 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3580 return -EFAULT;
3581 sigset_from_compat(&newset, &newset32);
3582 return sigsuspend(&newset);
3583#else
3584 /* on little-endian bitmaps don't care about granularity */
3585 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3586#endif
3587}
3588#endif
3589
3590#ifdef CONFIG_OLD_SIGSUSPEND
3591SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3592{
3593 sigset_t blocked;
3594 siginitset(&blocked, mask);
3595 return sigsuspend(&blocked);
3596}
3597#endif
3598#ifdef CONFIG_OLD_SIGSUSPEND3
3599SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3600{
3601 sigset_t blocked;
3602 siginitset(&blocked, mask);
3603 return sigsuspend(&blocked);
3604}
3605#endif
3606
3607__weak const char *arch_vma_name(struct vm_area_struct *vma)
3608{
3609 return NULL;
3610}
3611
3612void __init signals_init(void)
3613{
3614 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3615 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3616 != offsetof(struct siginfo, _sifields._pad));
3617
3618 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3619}
3620
3621#ifdef CONFIG_KGDB_KDB
3622#include <linux/kdb.h>
3623/*
3624 * kdb_send_sig_info - Allows kdb to send signals without exposing
3625 * signal internals. This function checks if the required locks are
3626 * available before calling the main signal code, to avoid kdb
3627 * deadlocks.
3628 */
3629void
3630kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3631{
3632 static struct task_struct *kdb_prev_t;
3633 int sig, new_t;
3634 if (!spin_trylock(&t->sighand->siglock)) {
3635 kdb_printf("Can't do kill command now.\n"
3636 "The sigmask lock is held somewhere else in "
3637 "kernel, try again later\n");
3638 return;
3639 }
3640 spin_unlock(&t->sighand->siglock);
3641 new_t = kdb_prev_t != t;
3642 kdb_prev_t = t;
3643 if (t->state != TASK_RUNNING && new_t) {
3644 kdb_printf("Process is not RUNNING, sending a signal from "
3645 "kdb risks deadlock\n"
3646 "on the run queue locks. "
3647 "The signal has _not_ been sent.\n"
3648 "Reissue the kill command if you want to risk "
3649 "the deadlock.\n");
3650 return;
3651 }
3652 sig = info->si_signo;
3653 if (send_sig_info(sig, info, t))
3654 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3655 sig, t->pid);
3656 else
3657 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3658}
3659#endif /* CONFIG_KGDB_KDB */
1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/security.h>
21#include <linux/syscalls.h>
22#include <linux/ptrace.h>
23#include <linux/signal.h>
24#include <linux/signalfd.h>
25#include <linux/ratelimit.h>
26#include <linux/tracehook.h>
27#include <linux/capability.h>
28#include <linux/freezer.h>
29#include <linux/pid_namespace.h>
30#include <linux/nsproxy.h>
31#define CREATE_TRACE_POINTS
32#include <trace/events/signal.h>
33
34#include <asm/param.h>
35#include <asm/uaccess.h>
36#include <asm/unistd.h>
37#include <asm/siginfo.h>
38#include "audit.h" /* audit_signal_info() */
39
40/*
41 * SLAB caches for signal bits.
42 */
43
44static struct kmem_cache *sigqueue_cachep;
45
46int print_fatal_signals __read_mostly;
47
48static void __user *sig_handler(struct task_struct *t, int sig)
49{
50 return t->sighand->action[sig - 1].sa.sa_handler;
51}
52
53static int sig_handler_ignored(void __user *handler, int sig)
54{
55 /* Is it explicitly or implicitly ignored? */
56 return handler == SIG_IGN ||
57 (handler == SIG_DFL && sig_kernel_ignore(sig));
58}
59
60static int sig_task_ignored(struct task_struct *t, int sig,
61 int from_ancestor_ns)
62{
63 void __user *handler;
64
65 handler = sig_handler(t, sig);
66
67 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
68 handler == SIG_DFL && !from_ancestor_ns)
69 return 1;
70
71 return sig_handler_ignored(handler, sig);
72}
73
74static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
75{
76 /*
77 * Blocked signals are never ignored, since the
78 * signal handler may change by the time it is
79 * unblocked.
80 */
81 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
82 return 0;
83
84 if (!sig_task_ignored(t, sig, from_ancestor_ns))
85 return 0;
86
87 /*
88 * Tracers may want to know about even ignored signals.
89 */
90 return !t->ptrace;
91}
92
93/*
94 * Re-calculate pending state from the set of locally pending
95 * signals, globally pending signals, and blocked signals.
96 */
97static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
98{
99 unsigned long ready;
100 long i;
101
102 switch (_NSIG_WORDS) {
103 default:
104 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
105 ready |= signal->sig[i] &~ blocked->sig[i];
106 break;
107
108 case 4: ready = signal->sig[3] &~ blocked->sig[3];
109 ready |= signal->sig[2] &~ blocked->sig[2];
110 ready |= signal->sig[1] &~ blocked->sig[1];
111 ready |= signal->sig[0] &~ blocked->sig[0];
112 break;
113
114 case 2: ready = signal->sig[1] &~ blocked->sig[1];
115 ready |= signal->sig[0] &~ blocked->sig[0];
116 break;
117
118 case 1: ready = signal->sig[0] &~ blocked->sig[0];
119 }
120 return ready != 0;
121}
122
123#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
124
125static int recalc_sigpending_tsk(struct task_struct *t)
126{
127 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
128 PENDING(&t->pending, &t->blocked) ||
129 PENDING(&t->signal->shared_pending, &t->blocked)) {
130 set_tsk_thread_flag(t, TIF_SIGPENDING);
131 return 1;
132 }
133 /*
134 * We must never clear the flag in another thread, or in current
135 * when it's possible the current syscall is returning -ERESTART*.
136 * So we don't clear it here, and only callers who know they should do.
137 */
138 return 0;
139}
140
141/*
142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
143 * This is superfluous when called on current, the wakeup is a harmless no-op.
144 */
145void recalc_sigpending_and_wake(struct task_struct *t)
146{
147 if (recalc_sigpending_tsk(t))
148 signal_wake_up(t, 0);
149}
150
151void recalc_sigpending(void)
152{
153 if (!recalc_sigpending_tsk(current) && !freezing(current))
154 clear_thread_flag(TIF_SIGPENDING);
155
156}
157
158/* Given the mask, find the first available signal that should be serviced. */
159
160#define SYNCHRONOUS_MASK \
161 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
162 sigmask(SIGTRAP) | sigmask(SIGFPE))
163
164int next_signal(struct sigpending *pending, sigset_t *mask)
165{
166 unsigned long i, *s, *m, x;
167 int sig = 0;
168
169 s = pending->signal.sig;
170 m = mask->sig;
171
172 /*
173 * Handle the first word specially: it contains the
174 * synchronous signals that need to be dequeued first.
175 */
176 x = *s &~ *m;
177 if (x) {
178 if (x & SYNCHRONOUS_MASK)
179 x &= SYNCHRONOUS_MASK;
180 sig = ffz(~x) + 1;
181 return sig;
182 }
183
184 switch (_NSIG_WORDS) {
185 default:
186 for (i = 1; i < _NSIG_WORDS; ++i) {
187 x = *++s &~ *++m;
188 if (!x)
189 continue;
190 sig = ffz(~x) + i*_NSIG_BPW + 1;
191 break;
192 }
193 break;
194
195 case 2:
196 x = s[1] &~ m[1];
197 if (!x)
198 break;
199 sig = ffz(~x) + _NSIG_BPW + 1;
200 break;
201
202 case 1:
203 /* Nothing to do */
204 break;
205 }
206
207 return sig;
208}
209
210static inline void print_dropped_signal(int sig)
211{
212 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
213
214 if (!print_fatal_signals)
215 return;
216
217 if (!__ratelimit(&ratelimit_state))
218 return;
219
220 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
221 current->comm, current->pid, sig);
222}
223
224/**
225 * task_set_jobctl_pending - set jobctl pending bits
226 * @task: target task
227 * @mask: pending bits to set
228 *
229 * Clear @mask from @task->jobctl. @mask must be subset of
230 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
231 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
232 * cleared. If @task is already being killed or exiting, this function
233 * becomes noop.
234 *
235 * CONTEXT:
236 * Must be called with @task->sighand->siglock held.
237 *
238 * RETURNS:
239 * %true if @mask is set, %false if made noop because @task was dying.
240 */
241bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
242{
243 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
244 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
245 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
246
247 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
248 return false;
249
250 if (mask & JOBCTL_STOP_SIGMASK)
251 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
252
253 task->jobctl |= mask;
254 return true;
255}
256
257/**
258 * task_clear_jobctl_trapping - clear jobctl trapping bit
259 * @task: target task
260 *
261 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
262 * Clear it and wake up the ptracer. Note that we don't need any further
263 * locking. @task->siglock guarantees that @task->parent points to the
264 * ptracer.
265 *
266 * CONTEXT:
267 * Must be called with @task->sighand->siglock held.
268 */
269void task_clear_jobctl_trapping(struct task_struct *task)
270{
271 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
272 task->jobctl &= ~JOBCTL_TRAPPING;
273 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
274 }
275}
276
277/**
278 * task_clear_jobctl_pending - clear jobctl pending bits
279 * @task: target task
280 * @mask: pending bits to clear
281 *
282 * Clear @mask from @task->jobctl. @mask must be subset of
283 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
284 * STOP bits are cleared together.
285 *
286 * If clearing of @mask leaves no stop or trap pending, this function calls
287 * task_clear_jobctl_trapping().
288 *
289 * CONTEXT:
290 * Must be called with @task->sighand->siglock held.
291 */
292void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
293{
294 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
295
296 if (mask & JOBCTL_STOP_PENDING)
297 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
298
299 task->jobctl &= ~mask;
300
301 if (!(task->jobctl & JOBCTL_PENDING_MASK))
302 task_clear_jobctl_trapping(task);
303}
304
305/**
306 * task_participate_group_stop - participate in a group stop
307 * @task: task participating in a group stop
308 *
309 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
310 * Group stop states are cleared and the group stop count is consumed if
311 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
312 * stop, the appropriate %SIGNAL_* flags are set.
313 *
314 * CONTEXT:
315 * Must be called with @task->sighand->siglock held.
316 *
317 * RETURNS:
318 * %true if group stop completion should be notified to the parent, %false
319 * otherwise.
320 */
321static bool task_participate_group_stop(struct task_struct *task)
322{
323 struct signal_struct *sig = task->signal;
324 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
325
326 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
327
328 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
329
330 if (!consume)
331 return false;
332
333 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
334 sig->group_stop_count--;
335
336 /*
337 * Tell the caller to notify completion iff we are entering into a
338 * fresh group stop. Read comment in do_signal_stop() for details.
339 */
340 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
341 sig->flags = SIGNAL_STOP_STOPPED;
342 return true;
343 }
344 return false;
345}
346
347/*
348 * allocate a new signal queue record
349 * - this may be called without locks if and only if t == current, otherwise an
350 * appropriate lock must be held to stop the target task from exiting
351 */
352static struct sigqueue *
353__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
354{
355 struct sigqueue *q = NULL;
356 struct user_struct *user;
357
358 /*
359 * Protect access to @t credentials. This can go away when all
360 * callers hold rcu read lock.
361 */
362 rcu_read_lock();
363 user = get_uid(__task_cred(t)->user);
364 atomic_inc(&user->sigpending);
365 rcu_read_unlock();
366
367 if (override_rlimit ||
368 atomic_read(&user->sigpending) <=
369 task_rlimit(t, RLIMIT_SIGPENDING)) {
370 q = kmem_cache_alloc(sigqueue_cachep, flags);
371 } else {
372 print_dropped_signal(sig);
373 }
374
375 if (unlikely(q == NULL)) {
376 atomic_dec(&user->sigpending);
377 free_uid(user);
378 } else {
379 INIT_LIST_HEAD(&q->list);
380 q->flags = 0;
381 q->user = user;
382 }
383
384 return q;
385}
386
387static void __sigqueue_free(struct sigqueue *q)
388{
389 if (q->flags & SIGQUEUE_PREALLOC)
390 return;
391 atomic_dec(&q->user->sigpending);
392 free_uid(q->user);
393 kmem_cache_free(sigqueue_cachep, q);
394}
395
396void flush_sigqueue(struct sigpending *queue)
397{
398 struct sigqueue *q;
399
400 sigemptyset(&queue->signal);
401 while (!list_empty(&queue->list)) {
402 q = list_entry(queue->list.next, struct sigqueue , list);
403 list_del_init(&q->list);
404 __sigqueue_free(q);
405 }
406}
407
408/*
409 * Flush all pending signals for a task.
410 */
411void __flush_signals(struct task_struct *t)
412{
413 clear_tsk_thread_flag(t, TIF_SIGPENDING);
414 flush_sigqueue(&t->pending);
415 flush_sigqueue(&t->signal->shared_pending);
416}
417
418void flush_signals(struct task_struct *t)
419{
420 unsigned long flags;
421
422 spin_lock_irqsave(&t->sighand->siglock, flags);
423 __flush_signals(t);
424 spin_unlock_irqrestore(&t->sighand->siglock, flags);
425}
426
427static void __flush_itimer_signals(struct sigpending *pending)
428{
429 sigset_t signal, retain;
430 struct sigqueue *q, *n;
431
432 signal = pending->signal;
433 sigemptyset(&retain);
434
435 list_for_each_entry_safe(q, n, &pending->list, list) {
436 int sig = q->info.si_signo;
437
438 if (likely(q->info.si_code != SI_TIMER)) {
439 sigaddset(&retain, sig);
440 } else {
441 sigdelset(&signal, sig);
442 list_del_init(&q->list);
443 __sigqueue_free(q);
444 }
445 }
446
447 sigorsets(&pending->signal, &signal, &retain);
448}
449
450void flush_itimer_signals(void)
451{
452 struct task_struct *tsk = current;
453 unsigned long flags;
454
455 spin_lock_irqsave(&tsk->sighand->siglock, flags);
456 __flush_itimer_signals(&tsk->pending);
457 __flush_itimer_signals(&tsk->signal->shared_pending);
458 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
459}
460
461void ignore_signals(struct task_struct *t)
462{
463 int i;
464
465 for (i = 0; i < _NSIG; ++i)
466 t->sighand->action[i].sa.sa_handler = SIG_IGN;
467
468 flush_signals(t);
469}
470
471/*
472 * Flush all handlers for a task.
473 */
474
475void
476flush_signal_handlers(struct task_struct *t, int force_default)
477{
478 int i;
479 struct k_sigaction *ka = &t->sighand->action[0];
480 for (i = _NSIG ; i != 0 ; i--) {
481 if (force_default || ka->sa.sa_handler != SIG_IGN)
482 ka->sa.sa_handler = SIG_DFL;
483 ka->sa.sa_flags = 0;
484 sigemptyset(&ka->sa.sa_mask);
485 ka++;
486 }
487}
488
489int unhandled_signal(struct task_struct *tsk, int sig)
490{
491 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
492 if (is_global_init(tsk))
493 return 1;
494 if (handler != SIG_IGN && handler != SIG_DFL)
495 return 0;
496 /* if ptraced, let the tracer determine */
497 return !tsk->ptrace;
498}
499
500/*
501 * Notify the system that a driver wants to block all signals for this
502 * process, and wants to be notified if any signals at all were to be
503 * sent/acted upon. If the notifier routine returns non-zero, then the
504 * signal will be acted upon after all. If the notifier routine returns 0,
505 * then then signal will be blocked. Only one block per process is
506 * allowed. priv is a pointer to private data that the notifier routine
507 * can use to determine if the signal should be blocked or not.
508 */
509void
510block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
511{
512 unsigned long flags;
513
514 spin_lock_irqsave(¤t->sighand->siglock, flags);
515 current->notifier_mask = mask;
516 current->notifier_data = priv;
517 current->notifier = notifier;
518 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
519}
520
521/* Notify the system that blocking has ended. */
522
523void
524unblock_all_signals(void)
525{
526 unsigned long flags;
527
528 spin_lock_irqsave(¤t->sighand->siglock, flags);
529 current->notifier = NULL;
530 current->notifier_data = NULL;
531 recalc_sigpending();
532 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
533}
534
535static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
536{
537 struct sigqueue *q, *first = NULL;
538
539 /*
540 * Collect the siginfo appropriate to this signal. Check if
541 * there is another siginfo for the same signal.
542 */
543 list_for_each_entry(q, &list->list, list) {
544 if (q->info.si_signo == sig) {
545 if (first)
546 goto still_pending;
547 first = q;
548 }
549 }
550
551 sigdelset(&list->signal, sig);
552
553 if (first) {
554still_pending:
555 list_del_init(&first->list);
556 copy_siginfo(info, &first->info);
557 __sigqueue_free(first);
558 } else {
559 /*
560 * Ok, it wasn't in the queue. This must be
561 * a fast-pathed signal or we must have been
562 * out of queue space. So zero out the info.
563 */
564 info->si_signo = sig;
565 info->si_errno = 0;
566 info->si_code = SI_USER;
567 info->si_pid = 0;
568 info->si_uid = 0;
569 }
570}
571
572static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
573 siginfo_t *info)
574{
575 int sig = next_signal(pending, mask);
576
577 if (sig) {
578 if (current->notifier) {
579 if (sigismember(current->notifier_mask, sig)) {
580 if (!(current->notifier)(current->notifier_data)) {
581 clear_thread_flag(TIF_SIGPENDING);
582 return 0;
583 }
584 }
585 }
586
587 collect_signal(sig, pending, info);
588 }
589
590 return sig;
591}
592
593/*
594 * Dequeue a signal and return the element to the caller, which is
595 * expected to free it.
596 *
597 * All callers have to hold the siglock.
598 */
599int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
600{
601 int signr;
602
603 /* We only dequeue private signals from ourselves, we don't let
604 * signalfd steal them
605 */
606 signr = __dequeue_signal(&tsk->pending, mask, info);
607 if (!signr) {
608 signr = __dequeue_signal(&tsk->signal->shared_pending,
609 mask, info);
610 /*
611 * itimer signal ?
612 *
613 * itimers are process shared and we restart periodic
614 * itimers in the signal delivery path to prevent DoS
615 * attacks in the high resolution timer case. This is
616 * compliant with the old way of self-restarting
617 * itimers, as the SIGALRM is a legacy signal and only
618 * queued once. Changing the restart behaviour to
619 * restart the timer in the signal dequeue path is
620 * reducing the timer noise on heavy loaded !highres
621 * systems too.
622 */
623 if (unlikely(signr == SIGALRM)) {
624 struct hrtimer *tmr = &tsk->signal->real_timer;
625
626 if (!hrtimer_is_queued(tmr) &&
627 tsk->signal->it_real_incr.tv64 != 0) {
628 hrtimer_forward(tmr, tmr->base->get_time(),
629 tsk->signal->it_real_incr);
630 hrtimer_restart(tmr);
631 }
632 }
633 }
634
635 recalc_sigpending();
636 if (!signr)
637 return 0;
638
639 if (unlikely(sig_kernel_stop(signr))) {
640 /*
641 * Set a marker that we have dequeued a stop signal. Our
642 * caller might release the siglock and then the pending
643 * stop signal it is about to process is no longer in the
644 * pending bitmasks, but must still be cleared by a SIGCONT
645 * (and overruled by a SIGKILL). So those cases clear this
646 * shared flag after we've set it. Note that this flag may
647 * remain set after the signal we return is ignored or
648 * handled. That doesn't matter because its only purpose
649 * is to alert stop-signal processing code when another
650 * processor has come along and cleared the flag.
651 */
652 current->jobctl |= JOBCTL_STOP_DEQUEUED;
653 }
654 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
655 /*
656 * Release the siglock to ensure proper locking order
657 * of timer locks outside of siglocks. Note, we leave
658 * irqs disabled here, since the posix-timers code is
659 * about to disable them again anyway.
660 */
661 spin_unlock(&tsk->sighand->siglock);
662 do_schedule_next_timer(info);
663 spin_lock(&tsk->sighand->siglock);
664 }
665 return signr;
666}
667
668/*
669 * Tell a process that it has a new active signal..
670 *
671 * NOTE! we rely on the previous spin_lock to
672 * lock interrupts for us! We can only be called with
673 * "siglock" held, and the local interrupt must
674 * have been disabled when that got acquired!
675 *
676 * No need to set need_resched since signal event passing
677 * goes through ->blocked
678 */
679void signal_wake_up(struct task_struct *t, int resume)
680{
681 unsigned int mask;
682
683 set_tsk_thread_flag(t, TIF_SIGPENDING);
684
685 /*
686 * For SIGKILL, we want to wake it up in the stopped/traced/killable
687 * case. We don't check t->state here because there is a race with it
688 * executing another processor and just now entering stopped state.
689 * By using wake_up_state, we ensure the process will wake up and
690 * handle its death signal.
691 */
692 mask = TASK_INTERRUPTIBLE;
693 if (resume)
694 mask |= TASK_WAKEKILL;
695 if (!wake_up_state(t, mask))
696 kick_process(t);
697}
698
699/*
700 * Remove signals in mask from the pending set and queue.
701 * Returns 1 if any signals were found.
702 *
703 * All callers must be holding the siglock.
704 *
705 * This version takes a sigset mask and looks at all signals,
706 * not just those in the first mask word.
707 */
708static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
709{
710 struct sigqueue *q, *n;
711 sigset_t m;
712
713 sigandsets(&m, mask, &s->signal);
714 if (sigisemptyset(&m))
715 return 0;
716
717 sigandnsets(&s->signal, &s->signal, mask);
718 list_for_each_entry_safe(q, n, &s->list, list) {
719 if (sigismember(mask, q->info.si_signo)) {
720 list_del_init(&q->list);
721 __sigqueue_free(q);
722 }
723 }
724 return 1;
725}
726/*
727 * Remove signals in mask from the pending set and queue.
728 * Returns 1 if any signals were found.
729 *
730 * All callers must be holding the siglock.
731 */
732static int rm_from_queue(unsigned long mask, struct sigpending *s)
733{
734 struct sigqueue *q, *n;
735
736 if (!sigtestsetmask(&s->signal, mask))
737 return 0;
738
739 sigdelsetmask(&s->signal, mask);
740 list_for_each_entry_safe(q, n, &s->list, list) {
741 if (q->info.si_signo < SIGRTMIN &&
742 (mask & sigmask(q->info.si_signo))) {
743 list_del_init(&q->list);
744 __sigqueue_free(q);
745 }
746 }
747 return 1;
748}
749
750static inline int is_si_special(const struct siginfo *info)
751{
752 return info <= SEND_SIG_FORCED;
753}
754
755static inline bool si_fromuser(const struct siginfo *info)
756{
757 return info == SEND_SIG_NOINFO ||
758 (!is_si_special(info) && SI_FROMUSER(info));
759}
760
761/*
762 * called with RCU read lock from check_kill_permission()
763 */
764static int kill_ok_by_cred(struct task_struct *t)
765{
766 const struct cred *cred = current_cred();
767 const struct cred *tcred = __task_cred(t);
768
769 if (cred->user->user_ns == tcred->user->user_ns &&
770 (cred->euid == tcred->suid ||
771 cred->euid == tcred->uid ||
772 cred->uid == tcred->suid ||
773 cred->uid == tcred->uid))
774 return 1;
775
776 if (ns_capable(tcred->user->user_ns, CAP_KILL))
777 return 1;
778
779 return 0;
780}
781
782/*
783 * Bad permissions for sending the signal
784 * - the caller must hold the RCU read lock
785 */
786static int check_kill_permission(int sig, struct siginfo *info,
787 struct task_struct *t)
788{
789 struct pid *sid;
790 int error;
791
792 if (!valid_signal(sig))
793 return -EINVAL;
794
795 if (!si_fromuser(info))
796 return 0;
797
798 error = audit_signal_info(sig, t); /* Let audit system see the signal */
799 if (error)
800 return error;
801
802 if (!same_thread_group(current, t) &&
803 !kill_ok_by_cred(t)) {
804 switch (sig) {
805 case SIGCONT:
806 sid = task_session(t);
807 /*
808 * We don't return the error if sid == NULL. The
809 * task was unhashed, the caller must notice this.
810 */
811 if (!sid || sid == task_session(current))
812 break;
813 default:
814 return -EPERM;
815 }
816 }
817
818 return security_task_kill(t, info, sig, 0);
819}
820
821/**
822 * ptrace_trap_notify - schedule trap to notify ptracer
823 * @t: tracee wanting to notify tracer
824 *
825 * This function schedules sticky ptrace trap which is cleared on the next
826 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
827 * ptracer.
828 *
829 * If @t is running, STOP trap will be taken. If trapped for STOP and
830 * ptracer is listening for events, tracee is woken up so that it can
831 * re-trap for the new event. If trapped otherwise, STOP trap will be
832 * eventually taken without returning to userland after the existing traps
833 * are finished by PTRACE_CONT.
834 *
835 * CONTEXT:
836 * Must be called with @task->sighand->siglock held.
837 */
838static void ptrace_trap_notify(struct task_struct *t)
839{
840 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
841 assert_spin_locked(&t->sighand->siglock);
842
843 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
844 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
845}
846
847/*
848 * Handle magic process-wide effects of stop/continue signals. Unlike
849 * the signal actions, these happen immediately at signal-generation
850 * time regardless of blocking, ignoring, or handling. This does the
851 * actual continuing for SIGCONT, but not the actual stopping for stop
852 * signals. The process stop is done as a signal action for SIG_DFL.
853 *
854 * Returns true if the signal should be actually delivered, otherwise
855 * it should be dropped.
856 */
857static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
858{
859 struct signal_struct *signal = p->signal;
860 struct task_struct *t;
861
862 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
863 /*
864 * The process is in the middle of dying, nothing to do.
865 */
866 } else if (sig_kernel_stop(sig)) {
867 /*
868 * This is a stop signal. Remove SIGCONT from all queues.
869 */
870 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
871 t = p;
872 do {
873 rm_from_queue(sigmask(SIGCONT), &t->pending);
874 } while_each_thread(p, t);
875 } else if (sig == SIGCONT) {
876 unsigned int why;
877 /*
878 * Remove all stop signals from all queues, wake all threads.
879 */
880 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
881 t = p;
882 do {
883 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
884 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
885 if (likely(!(t->ptrace & PT_SEIZED)))
886 wake_up_state(t, __TASK_STOPPED);
887 else
888 ptrace_trap_notify(t);
889 } while_each_thread(p, t);
890
891 /*
892 * Notify the parent with CLD_CONTINUED if we were stopped.
893 *
894 * If we were in the middle of a group stop, we pretend it
895 * was already finished, and then continued. Since SIGCHLD
896 * doesn't queue we report only CLD_STOPPED, as if the next
897 * CLD_CONTINUED was dropped.
898 */
899 why = 0;
900 if (signal->flags & SIGNAL_STOP_STOPPED)
901 why |= SIGNAL_CLD_CONTINUED;
902 else if (signal->group_stop_count)
903 why |= SIGNAL_CLD_STOPPED;
904
905 if (why) {
906 /*
907 * The first thread which returns from do_signal_stop()
908 * will take ->siglock, notice SIGNAL_CLD_MASK, and
909 * notify its parent. See get_signal_to_deliver().
910 */
911 signal->flags = why | SIGNAL_STOP_CONTINUED;
912 signal->group_stop_count = 0;
913 signal->group_exit_code = 0;
914 }
915 }
916
917 return !sig_ignored(p, sig, from_ancestor_ns);
918}
919
920/*
921 * Test if P wants to take SIG. After we've checked all threads with this,
922 * it's equivalent to finding no threads not blocking SIG. Any threads not
923 * blocking SIG were ruled out because they are not running and already
924 * have pending signals. Such threads will dequeue from the shared queue
925 * as soon as they're available, so putting the signal on the shared queue
926 * will be equivalent to sending it to one such thread.
927 */
928static inline int wants_signal(int sig, struct task_struct *p)
929{
930 if (sigismember(&p->blocked, sig))
931 return 0;
932 if (p->flags & PF_EXITING)
933 return 0;
934 if (sig == SIGKILL)
935 return 1;
936 if (task_is_stopped_or_traced(p))
937 return 0;
938 return task_curr(p) || !signal_pending(p);
939}
940
941static void complete_signal(int sig, struct task_struct *p, int group)
942{
943 struct signal_struct *signal = p->signal;
944 struct task_struct *t;
945
946 /*
947 * Now find a thread we can wake up to take the signal off the queue.
948 *
949 * If the main thread wants the signal, it gets first crack.
950 * Probably the least surprising to the average bear.
951 */
952 if (wants_signal(sig, p))
953 t = p;
954 else if (!group || thread_group_empty(p))
955 /*
956 * There is just one thread and it does not need to be woken.
957 * It will dequeue unblocked signals before it runs again.
958 */
959 return;
960 else {
961 /*
962 * Otherwise try to find a suitable thread.
963 */
964 t = signal->curr_target;
965 while (!wants_signal(sig, t)) {
966 t = next_thread(t);
967 if (t == signal->curr_target)
968 /*
969 * No thread needs to be woken.
970 * Any eligible threads will see
971 * the signal in the queue soon.
972 */
973 return;
974 }
975 signal->curr_target = t;
976 }
977
978 /*
979 * Found a killable thread. If the signal will be fatal,
980 * then start taking the whole group down immediately.
981 */
982 if (sig_fatal(p, sig) &&
983 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
984 !sigismember(&t->real_blocked, sig) &&
985 (sig == SIGKILL || !t->ptrace)) {
986 /*
987 * This signal will be fatal to the whole group.
988 */
989 if (!sig_kernel_coredump(sig)) {
990 /*
991 * Start a group exit and wake everybody up.
992 * This way we don't have other threads
993 * running and doing things after a slower
994 * thread has the fatal signal pending.
995 */
996 signal->flags = SIGNAL_GROUP_EXIT;
997 signal->group_exit_code = sig;
998 signal->group_stop_count = 0;
999 t = p;
1000 do {
1001 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1002 sigaddset(&t->pending.signal, SIGKILL);
1003 signal_wake_up(t, 1);
1004 } while_each_thread(p, t);
1005 return;
1006 }
1007 }
1008
1009 /*
1010 * The signal is already in the shared-pending queue.
1011 * Tell the chosen thread to wake up and dequeue it.
1012 */
1013 signal_wake_up(t, sig == SIGKILL);
1014 return;
1015}
1016
1017static inline int legacy_queue(struct sigpending *signals, int sig)
1018{
1019 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1020}
1021
1022static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1023 int group, int from_ancestor_ns)
1024{
1025 struct sigpending *pending;
1026 struct sigqueue *q;
1027 int override_rlimit;
1028
1029 trace_signal_generate(sig, info, t);
1030
1031 assert_spin_locked(&t->sighand->siglock);
1032
1033 if (!prepare_signal(sig, t, from_ancestor_ns))
1034 return 0;
1035
1036 pending = group ? &t->signal->shared_pending : &t->pending;
1037 /*
1038 * Short-circuit ignored signals and support queuing
1039 * exactly one non-rt signal, so that we can get more
1040 * detailed information about the cause of the signal.
1041 */
1042 if (legacy_queue(pending, sig))
1043 return 0;
1044 /*
1045 * fast-pathed signals for kernel-internal things like SIGSTOP
1046 * or SIGKILL.
1047 */
1048 if (info == SEND_SIG_FORCED)
1049 goto out_set;
1050
1051 /*
1052 * Real-time signals must be queued if sent by sigqueue, or
1053 * some other real-time mechanism. It is implementation
1054 * defined whether kill() does so. We attempt to do so, on
1055 * the principle of least surprise, but since kill is not
1056 * allowed to fail with EAGAIN when low on memory we just
1057 * make sure at least one signal gets delivered and don't
1058 * pass on the info struct.
1059 */
1060 if (sig < SIGRTMIN)
1061 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1062 else
1063 override_rlimit = 0;
1064
1065 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1066 override_rlimit);
1067 if (q) {
1068 list_add_tail(&q->list, &pending->list);
1069 switch ((unsigned long) info) {
1070 case (unsigned long) SEND_SIG_NOINFO:
1071 q->info.si_signo = sig;
1072 q->info.si_errno = 0;
1073 q->info.si_code = SI_USER;
1074 q->info.si_pid = task_tgid_nr_ns(current,
1075 task_active_pid_ns(t));
1076 q->info.si_uid = current_uid();
1077 break;
1078 case (unsigned long) SEND_SIG_PRIV:
1079 q->info.si_signo = sig;
1080 q->info.si_errno = 0;
1081 q->info.si_code = SI_KERNEL;
1082 q->info.si_pid = 0;
1083 q->info.si_uid = 0;
1084 break;
1085 default:
1086 copy_siginfo(&q->info, info);
1087 if (from_ancestor_ns)
1088 q->info.si_pid = 0;
1089 break;
1090 }
1091 } else if (!is_si_special(info)) {
1092 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1093 /*
1094 * Queue overflow, abort. We may abort if the
1095 * signal was rt and sent by user using something
1096 * other than kill().
1097 */
1098 trace_signal_overflow_fail(sig, group, info);
1099 return -EAGAIN;
1100 } else {
1101 /*
1102 * This is a silent loss of information. We still
1103 * send the signal, but the *info bits are lost.
1104 */
1105 trace_signal_lose_info(sig, group, info);
1106 }
1107 }
1108
1109out_set:
1110 signalfd_notify(t, sig);
1111 sigaddset(&pending->signal, sig);
1112 complete_signal(sig, t, group);
1113 return 0;
1114}
1115
1116static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1117 int group)
1118{
1119 int from_ancestor_ns = 0;
1120
1121#ifdef CONFIG_PID_NS
1122 from_ancestor_ns = si_fromuser(info) &&
1123 !task_pid_nr_ns(current, task_active_pid_ns(t));
1124#endif
1125
1126 return __send_signal(sig, info, t, group, from_ancestor_ns);
1127}
1128
1129static void print_fatal_signal(struct pt_regs *regs, int signr)
1130{
1131 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1132 current->comm, task_pid_nr(current), signr);
1133
1134#if defined(__i386__) && !defined(__arch_um__)
1135 printk("code at %08lx: ", regs->ip);
1136 {
1137 int i;
1138 for (i = 0; i < 16; i++) {
1139 unsigned char insn;
1140
1141 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1142 break;
1143 printk("%02x ", insn);
1144 }
1145 }
1146#endif
1147 printk("\n");
1148 preempt_disable();
1149 show_regs(regs);
1150 preempt_enable();
1151}
1152
1153static int __init setup_print_fatal_signals(char *str)
1154{
1155 get_option (&str, &print_fatal_signals);
1156
1157 return 1;
1158}
1159
1160__setup("print-fatal-signals=", setup_print_fatal_signals);
1161
1162int
1163__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1164{
1165 return send_signal(sig, info, p, 1);
1166}
1167
1168static int
1169specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1170{
1171 return send_signal(sig, info, t, 0);
1172}
1173
1174int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1175 bool group)
1176{
1177 unsigned long flags;
1178 int ret = -ESRCH;
1179
1180 if (lock_task_sighand(p, &flags)) {
1181 ret = send_signal(sig, info, p, group);
1182 unlock_task_sighand(p, &flags);
1183 }
1184
1185 return ret;
1186}
1187
1188/*
1189 * Force a signal that the process can't ignore: if necessary
1190 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1191 *
1192 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1193 * since we do not want to have a signal handler that was blocked
1194 * be invoked when user space had explicitly blocked it.
1195 *
1196 * We don't want to have recursive SIGSEGV's etc, for example,
1197 * that is why we also clear SIGNAL_UNKILLABLE.
1198 */
1199int
1200force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1201{
1202 unsigned long int flags;
1203 int ret, blocked, ignored;
1204 struct k_sigaction *action;
1205
1206 spin_lock_irqsave(&t->sighand->siglock, flags);
1207 action = &t->sighand->action[sig-1];
1208 ignored = action->sa.sa_handler == SIG_IGN;
1209 blocked = sigismember(&t->blocked, sig);
1210 if (blocked || ignored) {
1211 action->sa.sa_handler = SIG_DFL;
1212 if (blocked) {
1213 sigdelset(&t->blocked, sig);
1214 recalc_sigpending_and_wake(t);
1215 }
1216 }
1217 if (action->sa.sa_handler == SIG_DFL)
1218 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1219 ret = specific_send_sig_info(sig, info, t);
1220 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1221
1222 return ret;
1223}
1224
1225/*
1226 * Nuke all other threads in the group.
1227 */
1228int zap_other_threads(struct task_struct *p)
1229{
1230 struct task_struct *t = p;
1231 int count = 0;
1232
1233 p->signal->group_stop_count = 0;
1234
1235 while_each_thread(p, t) {
1236 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1237 count++;
1238
1239 /* Don't bother with already dead threads */
1240 if (t->exit_state)
1241 continue;
1242 sigaddset(&t->pending.signal, SIGKILL);
1243 signal_wake_up(t, 1);
1244 }
1245
1246 return count;
1247}
1248
1249struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1250 unsigned long *flags)
1251{
1252 struct sighand_struct *sighand;
1253
1254 for (;;) {
1255 local_irq_save(*flags);
1256 rcu_read_lock();
1257 sighand = rcu_dereference(tsk->sighand);
1258 if (unlikely(sighand == NULL)) {
1259 rcu_read_unlock();
1260 local_irq_restore(*flags);
1261 break;
1262 }
1263
1264 spin_lock(&sighand->siglock);
1265 if (likely(sighand == tsk->sighand)) {
1266 rcu_read_unlock();
1267 break;
1268 }
1269 spin_unlock(&sighand->siglock);
1270 rcu_read_unlock();
1271 local_irq_restore(*flags);
1272 }
1273
1274 return sighand;
1275}
1276
1277/*
1278 * send signal info to all the members of a group
1279 */
1280int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1281{
1282 int ret;
1283
1284 rcu_read_lock();
1285 ret = check_kill_permission(sig, info, p);
1286 rcu_read_unlock();
1287
1288 if (!ret && sig)
1289 ret = do_send_sig_info(sig, info, p, true);
1290
1291 return ret;
1292}
1293
1294/*
1295 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1296 * control characters do (^C, ^Z etc)
1297 * - the caller must hold at least a readlock on tasklist_lock
1298 */
1299int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1300{
1301 struct task_struct *p = NULL;
1302 int retval, success;
1303
1304 success = 0;
1305 retval = -ESRCH;
1306 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1307 int err = group_send_sig_info(sig, info, p);
1308 success |= !err;
1309 retval = err;
1310 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1311 return success ? 0 : retval;
1312}
1313
1314int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1315{
1316 int error = -ESRCH;
1317 struct task_struct *p;
1318
1319 rcu_read_lock();
1320retry:
1321 p = pid_task(pid, PIDTYPE_PID);
1322 if (p) {
1323 error = group_send_sig_info(sig, info, p);
1324 if (unlikely(error == -ESRCH))
1325 /*
1326 * The task was unhashed in between, try again.
1327 * If it is dead, pid_task() will return NULL,
1328 * if we race with de_thread() it will find the
1329 * new leader.
1330 */
1331 goto retry;
1332 }
1333 rcu_read_unlock();
1334
1335 return error;
1336}
1337
1338int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1339{
1340 int error;
1341 rcu_read_lock();
1342 error = kill_pid_info(sig, info, find_vpid(pid));
1343 rcu_read_unlock();
1344 return error;
1345}
1346
1347/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1348int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1349 uid_t uid, uid_t euid, u32 secid)
1350{
1351 int ret = -EINVAL;
1352 struct task_struct *p;
1353 const struct cred *pcred;
1354 unsigned long flags;
1355
1356 if (!valid_signal(sig))
1357 return ret;
1358
1359 rcu_read_lock();
1360 p = pid_task(pid, PIDTYPE_PID);
1361 if (!p) {
1362 ret = -ESRCH;
1363 goto out_unlock;
1364 }
1365 pcred = __task_cred(p);
1366 if (si_fromuser(info) &&
1367 euid != pcred->suid && euid != pcred->uid &&
1368 uid != pcred->suid && uid != pcred->uid) {
1369 ret = -EPERM;
1370 goto out_unlock;
1371 }
1372 ret = security_task_kill(p, info, sig, secid);
1373 if (ret)
1374 goto out_unlock;
1375
1376 if (sig) {
1377 if (lock_task_sighand(p, &flags)) {
1378 ret = __send_signal(sig, info, p, 1, 0);
1379 unlock_task_sighand(p, &flags);
1380 } else
1381 ret = -ESRCH;
1382 }
1383out_unlock:
1384 rcu_read_unlock();
1385 return ret;
1386}
1387EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1388
1389/*
1390 * kill_something_info() interprets pid in interesting ways just like kill(2).
1391 *
1392 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1393 * is probably wrong. Should make it like BSD or SYSV.
1394 */
1395
1396static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1397{
1398 int ret;
1399
1400 if (pid > 0) {
1401 rcu_read_lock();
1402 ret = kill_pid_info(sig, info, find_vpid(pid));
1403 rcu_read_unlock();
1404 return ret;
1405 }
1406
1407 read_lock(&tasklist_lock);
1408 if (pid != -1) {
1409 ret = __kill_pgrp_info(sig, info,
1410 pid ? find_vpid(-pid) : task_pgrp(current));
1411 } else {
1412 int retval = 0, count = 0;
1413 struct task_struct * p;
1414
1415 for_each_process(p) {
1416 if (task_pid_vnr(p) > 1 &&
1417 !same_thread_group(p, current)) {
1418 int err = group_send_sig_info(sig, info, p);
1419 ++count;
1420 if (err != -EPERM)
1421 retval = err;
1422 }
1423 }
1424 ret = count ? retval : -ESRCH;
1425 }
1426 read_unlock(&tasklist_lock);
1427
1428 return ret;
1429}
1430
1431/*
1432 * These are for backward compatibility with the rest of the kernel source.
1433 */
1434
1435int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1436{
1437 /*
1438 * Make sure legacy kernel users don't send in bad values
1439 * (normal paths check this in check_kill_permission).
1440 */
1441 if (!valid_signal(sig))
1442 return -EINVAL;
1443
1444 return do_send_sig_info(sig, info, p, false);
1445}
1446
1447#define __si_special(priv) \
1448 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1449
1450int
1451send_sig(int sig, struct task_struct *p, int priv)
1452{
1453 return send_sig_info(sig, __si_special(priv), p);
1454}
1455
1456void
1457force_sig(int sig, struct task_struct *p)
1458{
1459 force_sig_info(sig, SEND_SIG_PRIV, p);
1460}
1461
1462/*
1463 * When things go south during signal handling, we
1464 * will force a SIGSEGV. And if the signal that caused
1465 * the problem was already a SIGSEGV, we'll want to
1466 * make sure we don't even try to deliver the signal..
1467 */
1468int
1469force_sigsegv(int sig, struct task_struct *p)
1470{
1471 if (sig == SIGSEGV) {
1472 unsigned long flags;
1473 spin_lock_irqsave(&p->sighand->siglock, flags);
1474 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1475 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1476 }
1477 force_sig(SIGSEGV, p);
1478 return 0;
1479}
1480
1481int kill_pgrp(struct pid *pid, int sig, int priv)
1482{
1483 int ret;
1484
1485 read_lock(&tasklist_lock);
1486 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1487 read_unlock(&tasklist_lock);
1488
1489 return ret;
1490}
1491EXPORT_SYMBOL(kill_pgrp);
1492
1493int kill_pid(struct pid *pid, int sig, int priv)
1494{
1495 return kill_pid_info(sig, __si_special(priv), pid);
1496}
1497EXPORT_SYMBOL(kill_pid);
1498
1499/*
1500 * These functions support sending signals using preallocated sigqueue
1501 * structures. This is needed "because realtime applications cannot
1502 * afford to lose notifications of asynchronous events, like timer
1503 * expirations or I/O completions". In the case of POSIX Timers
1504 * we allocate the sigqueue structure from the timer_create. If this
1505 * allocation fails we are able to report the failure to the application
1506 * with an EAGAIN error.
1507 */
1508struct sigqueue *sigqueue_alloc(void)
1509{
1510 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1511
1512 if (q)
1513 q->flags |= SIGQUEUE_PREALLOC;
1514
1515 return q;
1516}
1517
1518void sigqueue_free(struct sigqueue *q)
1519{
1520 unsigned long flags;
1521 spinlock_t *lock = ¤t->sighand->siglock;
1522
1523 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1524 /*
1525 * We must hold ->siglock while testing q->list
1526 * to serialize with collect_signal() or with
1527 * __exit_signal()->flush_sigqueue().
1528 */
1529 spin_lock_irqsave(lock, flags);
1530 q->flags &= ~SIGQUEUE_PREALLOC;
1531 /*
1532 * If it is queued it will be freed when dequeued,
1533 * like the "regular" sigqueue.
1534 */
1535 if (!list_empty(&q->list))
1536 q = NULL;
1537 spin_unlock_irqrestore(lock, flags);
1538
1539 if (q)
1540 __sigqueue_free(q);
1541}
1542
1543int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1544{
1545 int sig = q->info.si_signo;
1546 struct sigpending *pending;
1547 unsigned long flags;
1548 int ret;
1549
1550 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1551
1552 ret = -1;
1553 if (!likely(lock_task_sighand(t, &flags)))
1554 goto ret;
1555
1556 ret = 1; /* the signal is ignored */
1557 if (!prepare_signal(sig, t, 0))
1558 goto out;
1559
1560 ret = 0;
1561 if (unlikely(!list_empty(&q->list))) {
1562 /*
1563 * If an SI_TIMER entry is already queue just increment
1564 * the overrun count.
1565 */
1566 BUG_ON(q->info.si_code != SI_TIMER);
1567 q->info.si_overrun++;
1568 goto out;
1569 }
1570 q->info.si_overrun = 0;
1571
1572 signalfd_notify(t, sig);
1573 pending = group ? &t->signal->shared_pending : &t->pending;
1574 list_add_tail(&q->list, &pending->list);
1575 sigaddset(&pending->signal, sig);
1576 complete_signal(sig, t, group);
1577out:
1578 unlock_task_sighand(t, &flags);
1579ret:
1580 return ret;
1581}
1582
1583/*
1584 * Let a parent know about the death of a child.
1585 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1586 *
1587 * Returns true if our parent ignored us and so we've switched to
1588 * self-reaping.
1589 */
1590bool do_notify_parent(struct task_struct *tsk, int sig)
1591{
1592 struct siginfo info;
1593 unsigned long flags;
1594 struct sighand_struct *psig;
1595 bool autoreap = false;
1596
1597 BUG_ON(sig == -1);
1598
1599 /* do_notify_parent_cldstop should have been called instead. */
1600 BUG_ON(task_is_stopped_or_traced(tsk));
1601
1602 BUG_ON(!tsk->ptrace &&
1603 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1604
1605 info.si_signo = sig;
1606 info.si_errno = 0;
1607 /*
1608 * we are under tasklist_lock here so our parent is tied to
1609 * us and cannot exit and release its namespace.
1610 *
1611 * the only it can is to switch its nsproxy with sys_unshare,
1612 * bu uncharing pid namespaces is not allowed, so we'll always
1613 * see relevant namespace
1614 *
1615 * write_lock() currently calls preempt_disable() which is the
1616 * same as rcu_read_lock(), but according to Oleg, this is not
1617 * correct to rely on this
1618 */
1619 rcu_read_lock();
1620 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1621 info.si_uid = __task_cred(tsk)->uid;
1622 rcu_read_unlock();
1623
1624 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1625 tsk->signal->utime));
1626 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1627 tsk->signal->stime));
1628
1629 info.si_status = tsk->exit_code & 0x7f;
1630 if (tsk->exit_code & 0x80)
1631 info.si_code = CLD_DUMPED;
1632 else if (tsk->exit_code & 0x7f)
1633 info.si_code = CLD_KILLED;
1634 else {
1635 info.si_code = CLD_EXITED;
1636 info.si_status = tsk->exit_code >> 8;
1637 }
1638
1639 psig = tsk->parent->sighand;
1640 spin_lock_irqsave(&psig->siglock, flags);
1641 if (!tsk->ptrace && sig == SIGCHLD &&
1642 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1643 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1644 /*
1645 * We are exiting and our parent doesn't care. POSIX.1
1646 * defines special semantics for setting SIGCHLD to SIG_IGN
1647 * or setting the SA_NOCLDWAIT flag: we should be reaped
1648 * automatically and not left for our parent's wait4 call.
1649 * Rather than having the parent do it as a magic kind of
1650 * signal handler, we just set this to tell do_exit that we
1651 * can be cleaned up without becoming a zombie. Note that
1652 * we still call __wake_up_parent in this case, because a
1653 * blocked sys_wait4 might now return -ECHILD.
1654 *
1655 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1656 * is implementation-defined: we do (if you don't want
1657 * it, just use SIG_IGN instead).
1658 */
1659 autoreap = true;
1660 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1661 sig = 0;
1662 }
1663 if (valid_signal(sig) && sig)
1664 __group_send_sig_info(sig, &info, tsk->parent);
1665 __wake_up_parent(tsk, tsk->parent);
1666 spin_unlock_irqrestore(&psig->siglock, flags);
1667
1668 return autoreap;
1669}
1670
1671/**
1672 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1673 * @tsk: task reporting the state change
1674 * @for_ptracer: the notification is for ptracer
1675 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1676 *
1677 * Notify @tsk's parent that the stopped/continued state has changed. If
1678 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1679 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1680 *
1681 * CONTEXT:
1682 * Must be called with tasklist_lock at least read locked.
1683 */
1684static void do_notify_parent_cldstop(struct task_struct *tsk,
1685 bool for_ptracer, int why)
1686{
1687 struct siginfo info;
1688 unsigned long flags;
1689 struct task_struct *parent;
1690 struct sighand_struct *sighand;
1691
1692 if (for_ptracer) {
1693 parent = tsk->parent;
1694 } else {
1695 tsk = tsk->group_leader;
1696 parent = tsk->real_parent;
1697 }
1698
1699 info.si_signo = SIGCHLD;
1700 info.si_errno = 0;
1701 /*
1702 * see comment in do_notify_parent() about the following 4 lines
1703 */
1704 rcu_read_lock();
1705 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1706 info.si_uid = __task_cred(tsk)->uid;
1707 rcu_read_unlock();
1708
1709 info.si_utime = cputime_to_clock_t(tsk->utime);
1710 info.si_stime = cputime_to_clock_t(tsk->stime);
1711
1712 info.si_code = why;
1713 switch (why) {
1714 case CLD_CONTINUED:
1715 info.si_status = SIGCONT;
1716 break;
1717 case CLD_STOPPED:
1718 info.si_status = tsk->signal->group_exit_code & 0x7f;
1719 break;
1720 case CLD_TRAPPED:
1721 info.si_status = tsk->exit_code & 0x7f;
1722 break;
1723 default:
1724 BUG();
1725 }
1726
1727 sighand = parent->sighand;
1728 spin_lock_irqsave(&sighand->siglock, flags);
1729 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1730 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1731 __group_send_sig_info(SIGCHLD, &info, parent);
1732 /*
1733 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1734 */
1735 __wake_up_parent(tsk, parent);
1736 spin_unlock_irqrestore(&sighand->siglock, flags);
1737}
1738
1739static inline int may_ptrace_stop(void)
1740{
1741 if (!likely(current->ptrace))
1742 return 0;
1743 /*
1744 * Are we in the middle of do_coredump?
1745 * If so and our tracer is also part of the coredump stopping
1746 * is a deadlock situation, and pointless because our tracer
1747 * is dead so don't allow us to stop.
1748 * If SIGKILL was already sent before the caller unlocked
1749 * ->siglock we must see ->core_state != NULL. Otherwise it
1750 * is safe to enter schedule().
1751 */
1752 if (unlikely(current->mm->core_state) &&
1753 unlikely(current->mm == current->parent->mm))
1754 return 0;
1755
1756 return 1;
1757}
1758
1759/*
1760 * Return non-zero if there is a SIGKILL that should be waking us up.
1761 * Called with the siglock held.
1762 */
1763static int sigkill_pending(struct task_struct *tsk)
1764{
1765 return sigismember(&tsk->pending.signal, SIGKILL) ||
1766 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1767}
1768
1769/*
1770 * This must be called with current->sighand->siglock held.
1771 *
1772 * This should be the path for all ptrace stops.
1773 * We always set current->last_siginfo while stopped here.
1774 * That makes it a way to test a stopped process for
1775 * being ptrace-stopped vs being job-control-stopped.
1776 *
1777 * If we actually decide not to stop at all because the tracer
1778 * is gone, we keep current->exit_code unless clear_code.
1779 */
1780static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1781 __releases(¤t->sighand->siglock)
1782 __acquires(¤t->sighand->siglock)
1783{
1784 bool gstop_done = false;
1785
1786 if (arch_ptrace_stop_needed(exit_code, info)) {
1787 /*
1788 * The arch code has something special to do before a
1789 * ptrace stop. This is allowed to block, e.g. for faults
1790 * on user stack pages. We can't keep the siglock while
1791 * calling arch_ptrace_stop, so we must release it now.
1792 * To preserve proper semantics, we must do this before
1793 * any signal bookkeeping like checking group_stop_count.
1794 * Meanwhile, a SIGKILL could come in before we retake the
1795 * siglock. That must prevent us from sleeping in TASK_TRACED.
1796 * So after regaining the lock, we must check for SIGKILL.
1797 */
1798 spin_unlock_irq(¤t->sighand->siglock);
1799 arch_ptrace_stop(exit_code, info);
1800 spin_lock_irq(¤t->sighand->siglock);
1801 if (sigkill_pending(current))
1802 return;
1803 }
1804
1805 /*
1806 * We're committing to trapping. TRACED should be visible before
1807 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1808 * Also, transition to TRACED and updates to ->jobctl should be
1809 * atomic with respect to siglock and should be done after the arch
1810 * hook as siglock is released and regrabbed across it.
1811 */
1812 set_current_state(TASK_TRACED);
1813
1814 current->last_siginfo = info;
1815 current->exit_code = exit_code;
1816
1817 /*
1818 * If @why is CLD_STOPPED, we're trapping to participate in a group
1819 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1820 * across siglock relocks since INTERRUPT was scheduled, PENDING
1821 * could be clear now. We act as if SIGCONT is received after
1822 * TASK_TRACED is entered - ignore it.
1823 */
1824 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1825 gstop_done = task_participate_group_stop(current);
1826
1827 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1828 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1829 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1830 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1831
1832 /* entering a trap, clear TRAPPING */
1833 task_clear_jobctl_trapping(current);
1834
1835 spin_unlock_irq(¤t->sighand->siglock);
1836 read_lock(&tasklist_lock);
1837 if (may_ptrace_stop()) {
1838 /*
1839 * Notify parents of the stop.
1840 *
1841 * While ptraced, there are two parents - the ptracer and
1842 * the real_parent of the group_leader. The ptracer should
1843 * know about every stop while the real parent is only
1844 * interested in the completion of group stop. The states
1845 * for the two don't interact with each other. Notify
1846 * separately unless they're gonna be duplicates.
1847 */
1848 do_notify_parent_cldstop(current, true, why);
1849 if (gstop_done && ptrace_reparented(current))
1850 do_notify_parent_cldstop(current, false, why);
1851
1852 /*
1853 * Don't want to allow preemption here, because
1854 * sys_ptrace() needs this task to be inactive.
1855 *
1856 * XXX: implement read_unlock_no_resched().
1857 */
1858 preempt_disable();
1859 read_unlock(&tasklist_lock);
1860 preempt_enable_no_resched();
1861 schedule();
1862 } else {
1863 /*
1864 * By the time we got the lock, our tracer went away.
1865 * Don't drop the lock yet, another tracer may come.
1866 *
1867 * If @gstop_done, the ptracer went away between group stop
1868 * completion and here. During detach, it would have set
1869 * JOBCTL_STOP_PENDING on us and we'll re-enter
1870 * TASK_STOPPED in do_signal_stop() on return, so notifying
1871 * the real parent of the group stop completion is enough.
1872 */
1873 if (gstop_done)
1874 do_notify_parent_cldstop(current, false, why);
1875
1876 __set_current_state(TASK_RUNNING);
1877 if (clear_code)
1878 current->exit_code = 0;
1879 read_unlock(&tasklist_lock);
1880 }
1881
1882 /*
1883 * While in TASK_TRACED, we were considered "frozen enough".
1884 * Now that we woke up, it's crucial if we're supposed to be
1885 * frozen that we freeze now before running anything substantial.
1886 */
1887 try_to_freeze();
1888
1889 /*
1890 * We are back. Now reacquire the siglock before touching
1891 * last_siginfo, so that we are sure to have synchronized with
1892 * any signal-sending on another CPU that wants to examine it.
1893 */
1894 spin_lock_irq(¤t->sighand->siglock);
1895 current->last_siginfo = NULL;
1896
1897 /* LISTENING can be set only during STOP traps, clear it */
1898 current->jobctl &= ~JOBCTL_LISTENING;
1899
1900 /*
1901 * Queued signals ignored us while we were stopped for tracing.
1902 * So check for any that we should take before resuming user mode.
1903 * This sets TIF_SIGPENDING, but never clears it.
1904 */
1905 recalc_sigpending_tsk(current);
1906}
1907
1908static void ptrace_do_notify(int signr, int exit_code, int why)
1909{
1910 siginfo_t info;
1911
1912 memset(&info, 0, sizeof info);
1913 info.si_signo = signr;
1914 info.si_code = exit_code;
1915 info.si_pid = task_pid_vnr(current);
1916 info.si_uid = current_uid();
1917
1918 /* Let the debugger run. */
1919 ptrace_stop(exit_code, why, 1, &info);
1920}
1921
1922void ptrace_notify(int exit_code)
1923{
1924 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1925
1926 spin_lock_irq(¤t->sighand->siglock);
1927 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1928 spin_unlock_irq(¤t->sighand->siglock);
1929}
1930
1931/**
1932 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1933 * @signr: signr causing group stop if initiating
1934 *
1935 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1936 * and participate in it. If already set, participate in the existing
1937 * group stop. If participated in a group stop (and thus slept), %true is
1938 * returned with siglock released.
1939 *
1940 * If ptraced, this function doesn't handle stop itself. Instead,
1941 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1942 * untouched. The caller must ensure that INTERRUPT trap handling takes
1943 * places afterwards.
1944 *
1945 * CONTEXT:
1946 * Must be called with @current->sighand->siglock held, which is released
1947 * on %true return.
1948 *
1949 * RETURNS:
1950 * %false if group stop is already cancelled or ptrace trap is scheduled.
1951 * %true if participated in group stop.
1952 */
1953static bool do_signal_stop(int signr)
1954 __releases(¤t->sighand->siglock)
1955{
1956 struct signal_struct *sig = current->signal;
1957
1958 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1959 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1960 struct task_struct *t;
1961
1962 /* signr will be recorded in task->jobctl for retries */
1963 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1964
1965 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1966 unlikely(signal_group_exit(sig)))
1967 return false;
1968 /*
1969 * There is no group stop already in progress. We must
1970 * initiate one now.
1971 *
1972 * While ptraced, a task may be resumed while group stop is
1973 * still in effect and then receive a stop signal and
1974 * initiate another group stop. This deviates from the
1975 * usual behavior as two consecutive stop signals can't
1976 * cause two group stops when !ptraced. That is why we
1977 * also check !task_is_stopped(t) below.
1978 *
1979 * The condition can be distinguished by testing whether
1980 * SIGNAL_STOP_STOPPED is already set. Don't generate
1981 * group_exit_code in such case.
1982 *
1983 * This is not necessary for SIGNAL_STOP_CONTINUED because
1984 * an intervening stop signal is required to cause two
1985 * continued events regardless of ptrace.
1986 */
1987 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1988 sig->group_exit_code = signr;
1989 else
1990 WARN_ON_ONCE(!current->ptrace);
1991
1992 sig->group_stop_count = 0;
1993
1994 if (task_set_jobctl_pending(current, signr | gstop))
1995 sig->group_stop_count++;
1996
1997 for (t = next_thread(current); t != current;
1998 t = next_thread(t)) {
1999 /*
2000 * Setting state to TASK_STOPPED for a group
2001 * stop is always done with the siglock held,
2002 * so this check has no races.
2003 */
2004 if (!task_is_stopped(t) &&
2005 task_set_jobctl_pending(t, signr | gstop)) {
2006 sig->group_stop_count++;
2007 if (likely(!(t->ptrace & PT_SEIZED)))
2008 signal_wake_up(t, 0);
2009 else
2010 ptrace_trap_notify(t);
2011 }
2012 }
2013 }
2014
2015 if (likely(!current->ptrace)) {
2016 int notify = 0;
2017
2018 /*
2019 * If there are no other threads in the group, or if there
2020 * is a group stop in progress and we are the last to stop,
2021 * report to the parent.
2022 */
2023 if (task_participate_group_stop(current))
2024 notify = CLD_STOPPED;
2025
2026 __set_current_state(TASK_STOPPED);
2027 spin_unlock_irq(¤t->sighand->siglock);
2028
2029 /*
2030 * Notify the parent of the group stop completion. Because
2031 * we're not holding either the siglock or tasklist_lock
2032 * here, ptracer may attach inbetween; however, this is for
2033 * group stop and should always be delivered to the real
2034 * parent of the group leader. The new ptracer will get
2035 * its notification when this task transitions into
2036 * TASK_TRACED.
2037 */
2038 if (notify) {
2039 read_lock(&tasklist_lock);
2040 do_notify_parent_cldstop(current, false, notify);
2041 read_unlock(&tasklist_lock);
2042 }
2043
2044 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2045 schedule();
2046 return true;
2047 } else {
2048 /*
2049 * While ptraced, group stop is handled by STOP trap.
2050 * Schedule it and let the caller deal with it.
2051 */
2052 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2053 return false;
2054 }
2055}
2056
2057/**
2058 * do_jobctl_trap - take care of ptrace jobctl traps
2059 *
2060 * When PT_SEIZED, it's used for both group stop and explicit
2061 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2062 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2063 * the stop signal; otherwise, %SIGTRAP.
2064 *
2065 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2066 * number as exit_code and no siginfo.
2067 *
2068 * CONTEXT:
2069 * Must be called with @current->sighand->siglock held, which may be
2070 * released and re-acquired before returning with intervening sleep.
2071 */
2072static void do_jobctl_trap(void)
2073{
2074 struct signal_struct *signal = current->signal;
2075 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2076
2077 if (current->ptrace & PT_SEIZED) {
2078 if (!signal->group_stop_count &&
2079 !(signal->flags & SIGNAL_STOP_STOPPED))
2080 signr = SIGTRAP;
2081 WARN_ON_ONCE(!signr);
2082 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2083 CLD_STOPPED);
2084 } else {
2085 WARN_ON_ONCE(!signr);
2086 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2087 current->exit_code = 0;
2088 }
2089}
2090
2091static int ptrace_signal(int signr, siginfo_t *info,
2092 struct pt_regs *regs, void *cookie)
2093{
2094 ptrace_signal_deliver(regs, cookie);
2095 /*
2096 * We do not check sig_kernel_stop(signr) but set this marker
2097 * unconditionally because we do not know whether debugger will
2098 * change signr. This flag has no meaning unless we are going
2099 * to stop after return from ptrace_stop(). In this case it will
2100 * be checked in do_signal_stop(), we should only stop if it was
2101 * not cleared by SIGCONT while we were sleeping. See also the
2102 * comment in dequeue_signal().
2103 */
2104 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2105 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2106
2107 /* We're back. Did the debugger cancel the sig? */
2108 signr = current->exit_code;
2109 if (signr == 0)
2110 return signr;
2111
2112 current->exit_code = 0;
2113
2114 /*
2115 * Update the siginfo structure if the signal has
2116 * changed. If the debugger wanted something
2117 * specific in the siginfo structure then it should
2118 * have updated *info via PTRACE_SETSIGINFO.
2119 */
2120 if (signr != info->si_signo) {
2121 info->si_signo = signr;
2122 info->si_errno = 0;
2123 info->si_code = SI_USER;
2124 info->si_pid = task_pid_vnr(current->parent);
2125 info->si_uid = task_uid(current->parent);
2126 }
2127
2128 /* If the (new) signal is now blocked, requeue it. */
2129 if (sigismember(¤t->blocked, signr)) {
2130 specific_send_sig_info(signr, info, current);
2131 signr = 0;
2132 }
2133
2134 return signr;
2135}
2136
2137int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2138 struct pt_regs *regs, void *cookie)
2139{
2140 struct sighand_struct *sighand = current->sighand;
2141 struct signal_struct *signal = current->signal;
2142 int signr;
2143
2144relock:
2145 /*
2146 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2147 * While in TASK_STOPPED, we were considered "frozen enough".
2148 * Now that we woke up, it's crucial if we're supposed to be
2149 * frozen that we freeze now before running anything substantial.
2150 */
2151 try_to_freeze();
2152
2153 spin_lock_irq(&sighand->siglock);
2154 /*
2155 * Every stopped thread goes here after wakeup. Check to see if
2156 * we should notify the parent, prepare_signal(SIGCONT) encodes
2157 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2158 */
2159 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2160 int why;
2161
2162 if (signal->flags & SIGNAL_CLD_CONTINUED)
2163 why = CLD_CONTINUED;
2164 else
2165 why = CLD_STOPPED;
2166
2167 signal->flags &= ~SIGNAL_CLD_MASK;
2168
2169 spin_unlock_irq(&sighand->siglock);
2170
2171 /*
2172 * Notify the parent that we're continuing. This event is
2173 * always per-process and doesn't make whole lot of sense
2174 * for ptracers, who shouldn't consume the state via
2175 * wait(2) either, but, for backward compatibility, notify
2176 * the ptracer of the group leader too unless it's gonna be
2177 * a duplicate.
2178 */
2179 read_lock(&tasklist_lock);
2180 do_notify_parent_cldstop(current, false, why);
2181
2182 if (ptrace_reparented(current->group_leader))
2183 do_notify_parent_cldstop(current->group_leader,
2184 true, why);
2185 read_unlock(&tasklist_lock);
2186
2187 goto relock;
2188 }
2189
2190 for (;;) {
2191 struct k_sigaction *ka;
2192
2193 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2194 do_signal_stop(0))
2195 goto relock;
2196
2197 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2198 do_jobctl_trap();
2199 spin_unlock_irq(&sighand->siglock);
2200 goto relock;
2201 }
2202
2203 signr = dequeue_signal(current, ¤t->blocked, info);
2204
2205 if (!signr)
2206 break; /* will return 0 */
2207
2208 if (unlikely(current->ptrace) && signr != SIGKILL) {
2209 signr = ptrace_signal(signr, info,
2210 regs, cookie);
2211 if (!signr)
2212 continue;
2213 }
2214
2215 ka = &sighand->action[signr-1];
2216
2217 /* Trace actually delivered signals. */
2218 trace_signal_deliver(signr, info, ka);
2219
2220 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2221 continue;
2222 if (ka->sa.sa_handler != SIG_DFL) {
2223 /* Run the handler. */
2224 *return_ka = *ka;
2225
2226 if (ka->sa.sa_flags & SA_ONESHOT)
2227 ka->sa.sa_handler = SIG_DFL;
2228
2229 break; /* will return non-zero "signr" value */
2230 }
2231
2232 /*
2233 * Now we are doing the default action for this signal.
2234 */
2235 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2236 continue;
2237
2238 /*
2239 * Global init gets no signals it doesn't want.
2240 * Container-init gets no signals it doesn't want from same
2241 * container.
2242 *
2243 * Note that if global/container-init sees a sig_kernel_only()
2244 * signal here, the signal must have been generated internally
2245 * or must have come from an ancestor namespace. In either
2246 * case, the signal cannot be dropped.
2247 */
2248 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2249 !sig_kernel_only(signr))
2250 continue;
2251
2252 if (sig_kernel_stop(signr)) {
2253 /*
2254 * The default action is to stop all threads in
2255 * the thread group. The job control signals
2256 * do nothing in an orphaned pgrp, but SIGSTOP
2257 * always works. Note that siglock needs to be
2258 * dropped during the call to is_orphaned_pgrp()
2259 * because of lock ordering with tasklist_lock.
2260 * This allows an intervening SIGCONT to be posted.
2261 * We need to check for that and bail out if necessary.
2262 */
2263 if (signr != SIGSTOP) {
2264 spin_unlock_irq(&sighand->siglock);
2265
2266 /* signals can be posted during this window */
2267
2268 if (is_current_pgrp_orphaned())
2269 goto relock;
2270
2271 spin_lock_irq(&sighand->siglock);
2272 }
2273
2274 if (likely(do_signal_stop(info->si_signo))) {
2275 /* It released the siglock. */
2276 goto relock;
2277 }
2278
2279 /*
2280 * We didn't actually stop, due to a race
2281 * with SIGCONT or something like that.
2282 */
2283 continue;
2284 }
2285
2286 spin_unlock_irq(&sighand->siglock);
2287
2288 /*
2289 * Anything else is fatal, maybe with a core dump.
2290 */
2291 current->flags |= PF_SIGNALED;
2292
2293 if (sig_kernel_coredump(signr)) {
2294 if (print_fatal_signals)
2295 print_fatal_signal(regs, info->si_signo);
2296 /*
2297 * If it was able to dump core, this kills all
2298 * other threads in the group and synchronizes with
2299 * their demise. If we lost the race with another
2300 * thread getting here, it set group_exit_code
2301 * first and our do_group_exit call below will use
2302 * that value and ignore the one we pass it.
2303 */
2304 do_coredump(info->si_signo, info->si_signo, regs);
2305 }
2306
2307 /*
2308 * Death signals, no core dump.
2309 */
2310 do_group_exit(info->si_signo);
2311 /* NOTREACHED */
2312 }
2313 spin_unlock_irq(&sighand->siglock);
2314 return signr;
2315}
2316
2317/*
2318 * It could be that complete_signal() picked us to notify about the
2319 * group-wide signal. Other threads should be notified now to take
2320 * the shared signals in @which since we will not.
2321 */
2322static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2323{
2324 sigset_t retarget;
2325 struct task_struct *t;
2326
2327 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2328 if (sigisemptyset(&retarget))
2329 return;
2330
2331 t = tsk;
2332 while_each_thread(tsk, t) {
2333 if (t->flags & PF_EXITING)
2334 continue;
2335
2336 if (!has_pending_signals(&retarget, &t->blocked))
2337 continue;
2338 /* Remove the signals this thread can handle. */
2339 sigandsets(&retarget, &retarget, &t->blocked);
2340
2341 if (!signal_pending(t))
2342 signal_wake_up(t, 0);
2343
2344 if (sigisemptyset(&retarget))
2345 break;
2346 }
2347}
2348
2349void exit_signals(struct task_struct *tsk)
2350{
2351 int group_stop = 0;
2352 sigset_t unblocked;
2353
2354 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2355 tsk->flags |= PF_EXITING;
2356 return;
2357 }
2358
2359 spin_lock_irq(&tsk->sighand->siglock);
2360 /*
2361 * From now this task is not visible for group-wide signals,
2362 * see wants_signal(), do_signal_stop().
2363 */
2364 tsk->flags |= PF_EXITING;
2365 if (!signal_pending(tsk))
2366 goto out;
2367
2368 unblocked = tsk->blocked;
2369 signotset(&unblocked);
2370 retarget_shared_pending(tsk, &unblocked);
2371
2372 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2373 task_participate_group_stop(tsk))
2374 group_stop = CLD_STOPPED;
2375out:
2376 spin_unlock_irq(&tsk->sighand->siglock);
2377
2378 /*
2379 * If group stop has completed, deliver the notification. This
2380 * should always go to the real parent of the group leader.
2381 */
2382 if (unlikely(group_stop)) {
2383 read_lock(&tasklist_lock);
2384 do_notify_parent_cldstop(tsk, false, group_stop);
2385 read_unlock(&tasklist_lock);
2386 }
2387}
2388
2389EXPORT_SYMBOL(recalc_sigpending);
2390EXPORT_SYMBOL_GPL(dequeue_signal);
2391EXPORT_SYMBOL(flush_signals);
2392EXPORT_SYMBOL(force_sig);
2393EXPORT_SYMBOL(send_sig);
2394EXPORT_SYMBOL(send_sig_info);
2395EXPORT_SYMBOL(sigprocmask);
2396EXPORT_SYMBOL(block_all_signals);
2397EXPORT_SYMBOL(unblock_all_signals);
2398
2399
2400/*
2401 * System call entry points.
2402 */
2403
2404/**
2405 * sys_restart_syscall - restart a system call
2406 */
2407SYSCALL_DEFINE0(restart_syscall)
2408{
2409 struct restart_block *restart = ¤t_thread_info()->restart_block;
2410 return restart->fn(restart);
2411}
2412
2413long do_no_restart_syscall(struct restart_block *param)
2414{
2415 return -EINTR;
2416}
2417
2418static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2419{
2420 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2421 sigset_t newblocked;
2422 /* A set of now blocked but previously unblocked signals. */
2423 sigandnsets(&newblocked, newset, ¤t->blocked);
2424 retarget_shared_pending(tsk, &newblocked);
2425 }
2426 tsk->blocked = *newset;
2427 recalc_sigpending();
2428}
2429
2430/**
2431 * set_current_blocked - change current->blocked mask
2432 * @newset: new mask
2433 *
2434 * It is wrong to change ->blocked directly, this helper should be used
2435 * to ensure the process can't miss a shared signal we are going to block.
2436 */
2437void set_current_blocked(const sigset_t *newset)
2438{
2439 struct task_struct *tsk = current;
2440
2441 spin_lock_irq(&tsk->sighand->siglock);
2442 __set_task_blocked(tsk, newset);
2443 spin_unlock_irq(&tsk->sighand->siglock);
2444}
2445
2446/*
2447 * This is also useful for kernel threads that want to temporarily
2448 * (or permanently) block certain signals.
2449 *
2450 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2451 * interface happily blocks "unblockable" signals like SIGKILL
2452 * and friends.
2453 */
2454int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2455{
2456 struct task_struct *tsk = current;
2457 sigset_t newset;
2458
2459 /* Lockless, only current can change ->blocked, never from irq */
2460 if (oldset)
2461 *oldset = tsk->blocked;
2462
2463 switch (how) {
2464 case SIG_BLOCK:
2465 sigorsets(&newset, &tsk->blocked, set);
2466 break;
2467 case SIG_UNBLOCK:
2468 sigandnsets(&newset, &tsk->blocked, set);
2469 break;
2470 case SIG_SETMASK:
2471 newset = *set;
2472 break;
2473 default:
2474 return -EINVAL;
2475 }
2476
2477 set_current_blocked(&newset);
2478 return 0;
2479}
2480
2481/**
2482 * sys_rt_sigprocmask - change the list of currently blocked signals
2483 * @how: whether to add, remove, or set signals
2484 * @nset: stores pending signals
2485 * @oset: previous value of signal mask if non-null
2486 * @sigsetsize: size of sigset_t type
2487 */
2488SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2489 sigset_t __user *, oset, size_t, sigsetsize)
2490{
2491 sigset_t old_set, new_set;
2492 int error;
2493
2494 /* XXX: Don't preclude handling different sized sigset_t's. */
2495 if (sigsetsize != sizeof(sigset_t))
2496 return -EINVAL;
2497
2498 old_set = current->blocked;
2499
2500 if (nset) {
2501 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2502 return -EFAULT;
2503 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2504
2505 error = sigprocmask(how, &new_set, NULL);
2506 if (error)
2507 return error;
2508 }
2509
2510 if (oset) {
2511 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2512 return -EFAULT;
2513 }
2514
2515 return 0;
2516}
2517
2518long do_sigpending(void __user *set, unsigned long sigsetsize)
2519{
2520 long error = -EINVAL;
2521 sigset_t pending;
2522
2523 if (sigsetsize > sizeof(sigset_t))
2524 goto out;
2525
2526 spin_lock_irq(¤t->sighand->siglock);
2527 sigorsets(&pending, ¤t->pending.signal,
2528 ¤t->signal->shared_pending.signal);
2529 spin_unlock_irq(¤t->sighand->siglock);
2530
2531 /* Outside the lock because only this thread touches it. */
2532 sigandsets(&pending, ¤t->blocked, &pending);
2533
2534 error = -EFAULT;
2535 if (!copy_to_user(set, &pending, sigsetsize))
2536 error = 0;
2537
2538out:
2539 return error;
2540}
2541
2542/**
2543 * sys_rt_sigpending - examine a pending signal that has been raised
2544 * while blocked
2545 * @set: stores pending signals
2546 * @sigsetsize: size of sigset_t type or larger
2547 */
2548SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2549{
2550 return do_sigpending(set, sigsetsize);
2551}
2552
2553#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2554
2555int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2556{
2557 int err;
2558
2559 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2560 return -EFAULT;
2561 if (from->si_code < 0)
2562 return __copy_to_user(to, from, sizeof(siginfo_t))
2563 ? -EFAULT : 0;
2564 /*
2565 * If you change siginfo_t structure, please be sure
2566 * this code is fixed accordingly.
2567 * Please remember to update the signalfd_copyinfo() function
2568 * inside fs/signalfd.c too, in case siginfo_t changes.
2569 * It should never copy any pad contained in the structure
2570 * to avoid security leaks, but must copy the generic
2571 * 3 ints plus the relevant union member.
2572 */
2573 err = __put_user(from->si_signo, &to->si_signo);
2574 err |= __put_user(from->si_errno, &to->si_errno);
2575 err |= __put_user((short)from->si_code, &to->si_code);
2576 switch (from->si_code & __SI_MASK) {
2577 case __SI_KILL:
2578 err |= __put_user(from->si_pid, &to->si_pid);
2579 err |= __put_user(from->si_uid, &to->si_uid);
2580 break;
2581 case __SI_TIMER:
2582 err |= __put_user(from->si_tid, &to->si_tid);
2583 err |= __put_user(from->si_overrun, &to->si_overrun);
2584 err |= __put_user(from->si_ptr, &to->si_ptr);
2585 break;
2586 case __SI_POLL:
2587 err |= __put_user(from->si_band, &to->si_band);
2588 err |= __put_user(from->si_fd, &to->si_fd);
2589 break;
2590 case __SI_FAULT:
2591 err |= __put_user(from->si_addr, &to->si_addr);
2592#ifdef __ARCH_SI_TRAPNO
2593 err |= __put_user(from->si_trapno, &to->si_trapno);
2594#endif
2595#ifdef BUS_MCEERR_AO
2596 /*
2597 * Other callers might not initialize the si_lsb field,
2598 * so check explicitly for the right codes here.
2599 */
2600 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2601 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2602#endif
2603 break;
2604 case __SI_CHLD:
2605 err |= __put_user(from->si_pid, &to->si_pid);
2606 err |= __put_user(from->si_uid, &to->si_uid);
2607 err |= __put_user(from->si_status, &to->si_status);
2608 err |= __put_user(from->si_utime, &to->si_utime);
2609 err |= __put_user(from->si_stime, &to->si_stime);
2610 break;
2611 case __SI_RT: /* This is not generated by the kernel as of now. */
2612 case __SI_MESGQ: /* But this is */
2613 err |= __put_user(from->si_pid, &to->si_pid);
2614 err |= __put_user(from->si_uid, &to->si_uid);
2615 err |= __put_user(from->si_ptr, &to->si_ptr);
2616 break;
2617 default: /* this is just in case for now ... */
2618 err |= __put_user(from->si_pid, &to->si_pid);
2619 err |= __put_user(from->si_uid, &to->si_uid);
2620 break;
2621 }
2622 return err;
2623}
2624
2625#endif
2626
2627/**
2628 * do_sigtimedwait - wait for queued signals specified in @which
2629 * @which: queued signals to wait for
2630 * @info: if non-null, the signal's siginfo is returned here
2631 * @ts: upper bound on process time suspension
2632 */
2633int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2634 const struct timespec *ts)
2635{
2636 struct task_struct *tsk = current;
2637 long timeout = MAX_SCHEDULE_TIMEOUT;
2638 sigset_t mask = *which;
2639 int sig;
2640
2641 if (ts) {
2642 if (!timespec_valid(ts))
2643 return -EINVAL;
2644 timeout = timespec_to_jiffies(ts);
2645 /*
2646 * We can be close to the next tick, add another one
2647 * to ensure we will wait at least the time asked for.
2648 */
2649 if (ts->tv_sec || ts->tv_nsec)
2650 timeout++;
2651 }
2652
2653 /*
2654 * Invert the set of allowed signals to get those we want to block.
2655 */
2656 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2657 signotset(&mask);
2658
2659 spin_lock_irq(&tsk->sighand->siglock);
2660 sig = dequeue_signal(tsk, &mask, info);
2661 if (!sig && timeout) {
2662 /*
2663 * None ready, temporarily unblock those we're interested
2664 * while we are sleeping in so that we'll be awakened when
2665 * they arrive. Unblocking is always fine, we can avoid
2666 * set_current_blocked().
2667 */
2668 tsk->real_blocked = tsk->blocked;
2669 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2670 recalc_sigpending();
2671 spin_unlock_irq(&tsk->sighand->siglock);
2672
2673 timeout = schedule_timeout_interruptible(timeout);
2674
2675 spin_lock_irq(&tsk->sighand->siglock);
2676 __set_task_blocked(tsk, &tsk->real_blocked);
2677 siginitset(&tsk->real_blocked, 0);
2678 sig = dequeue_signal(tsk, &mask, info);
2679 }
2680 spin_unlock_irq(&tsk->sighand->siglock);
2681
2682 if (sig)
2683 return sig;
2684 return timeout ? -EINTR : -EAGAIN;
2685}
2686
2687/**
2688 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2689 * in @uthese
2690 * @uthese: queued signals to wait for
2691 * @uinfo: if non-null, the signal's siginfo is returned here
2692 * @uts: upper bound on process time suspension
2693 * @sigsetsize: size of sigset_t type
2694 */
2695SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2696 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2697 size_t, sigsetsize)
2698{
2699 sigset_t these;
2700 struct timespec ts;
2701 siginfo_t info;
2702 int ret;
2703
2704 /* XXX: Don't preclude handling different sized sigset_t's. */
2705 if (sigsetsize != sizeof(sigset_t))
2706 return -EINVAL;
2707
2708 if (copy_from_user(&these, uthese, sizeof(these)))
2709 return -EFAULT;
2710
2711 if (uts) {
2712 if (copy_from_user(&ts, uts, sizeof(ts)))
2713 return -EFAULT;
2714 }
2715
2716 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2717
2718 if (ret > 0 && uinfo) {
2719 if (copy_siginfo_to_user(uinfo, &info))
2720 ret = -EFAULT;
2721 }
2722
2723 return ret;
2724}
2725
2726/**
2727 * sys_kill - send a signal to a process
2728 * @pid: the PID of the process
2729 * @sig: signal to be sent
2730 */
2731SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2732{
2733 struct siginfo info;
2734
2735 info.si_signo = sig;
2736 info.si_errno = 0;
2737 info.si_code = SI_USER;
2738 info.si_pid = task_tgid_vnr(current);
2739 info.si_uid = current_uid();
2740
2741 return kill_something_info(sig, &info, pid);
2742}
2743
2744static int
2745do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2746{
2747 struct task_struct *p;
2748 int error = -ESRCH;
2749
2750 rcu_read_lock();
2751 p = find_task_by_vpid(pid);
2752 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2753 error = check_kill_permission(sig, info, p);
2754 /*
2755 * The null signal is a permissions and process existence
2756 * probe. No signal is actually delivered.
2757 */
2758 if (!error && sig) {
2759 error = do_send_sig_info(sig, info, p, false);
2760 /*
2761 * If lock_task_sighand() failed we pretend the task
2762 * dies after receiving the signal. The window is tiny,
2763 * and the signal is private anyway.
2764 */
2765 if (unlikely(error == -ESRCH))
2766 error = 0;
2767 }
2768 }
2769 rcu_read_unlock();
2770
2771 return error;
2772}
2773
2774static int do_tkill(pid_t tgid, pid_t pid, int sig)
2775{
2776 struct siginfo info;
2777
2778 info.si_signo = sig;
2779 info.si_errno = 0;
2780 info.si_code = SI_TKILL;
2781 info.si_pid = task_tgid_vnr(current);
2782 info.si_uid = current_uid();
2783
2784 return do_send_specific(tgid, pid, sig, &info);
2785}
2786
2787/**
2788 * sys_tgkill - send signal to one specific thread
2789 * @tgid: the thread group ID of the thread
2790 * @pid: the PID of the thread
2791 * @sig: signal to be sent
2792 *
2793 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2794 * exists but it's not belonging to the target process anymore. This
2795 * method solves the problem of threads exiting and PIDs getting reused.
2796 */
2797SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2798{
2799 /* This is only valid for single tasks */
2800 if (pid <= 0 || tgid <= 0)
2801 return -EINVAL;
2802
2803 return do_tkill(tgid, pid, sig);
2804}
2805
2806/**
2807 * sys_tkill - send signal to one specific task
2808 * @pid: the PID of the task
2809 * @sig: signal to be sent
2810 *
2811 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2812 */
2813SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2814{
2815 /* This is only valid for single tasks */
2816 if (pid <= 0)
2817 return -EINVAL;
2818
2819 return do_tkill(0, pid, sig);
2820}
2821
2822/**
2823 * sys_rt_sigqueueinfo - send signal information to a signal
2824 * @pid: the PID of the thread
2825 * @sig: signal to be sent
2826 * @uinfo: signal info to be sent
2827 */
2828SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2829 siginfo_t __user *, uinfo)
2830{
2831 siginfo_t info;
2832
2833 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2834 return -EFAULT;
2835
2836 /* Not even root can pretend to send signals from the kernel.
2837 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2838 */
2839 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2840 /* We used to allow any < 0 si_code */
2841 WARN_ON_ONCE(info.si_code < 0);
2842 return -EPERM;
2843 }
2844 info.si_signo = sig;
2845
2846 /* POSIX.1b doesn't mention process groups. */
2847 return kill_proc_info(sig, &info, pid);
2848}
2849
2850long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2851{
2852 /* This is only valid for single tasks */
2853 if (pid <= 0 || tgid <= 0)
2854 return -EINVAL;
2855
2856 /* Not even root can pretend to send signals from the kernel.
2857 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2858 */
2859 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2860 /* We used to allow any < 0 si_code */
2861 WARN_ON_ONCE(info->si_code < 0);
2862 return -EPERM;
2863 }
2864 info->si_signo = sig;
2865
2866 return do_send_specific(tgid, pid, sig, info);
2867}
2868
2869SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2870 siginfo_t __user *, uinfo)
2871{
2872 siginfo_t info;
2873
2874 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2875 return -EFAULT;
2876
2877 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2878}
2879
2880int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2881{
2882 struct task_struct *t = current;
2883 struct k_sigaction *k;
2884 sigset_t mask;
2885
2886 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2887 return -EINVAL;
2888
2889 k = &t->sighand->action[sig-1];
2890
2891 spin_lock_irq(¤t->sighand->siglock);
2892 if (oact)
2893 *oact = *k;
2894
2895 if (act) {
2896 sigdelsetmask(&act->sa.sa_mask,
2897 sigmask(SIGKILL) | sigmask(SIGSTOP));
2898 *k = *act;
2899 /*
2900 * POSIX 3.3.1.3:
2901 * "Setting a signal action to SIG_IGN for a signal that is
2902 * pending shall cause the pending signal to be discarded,
2903 * whether or not it is blocked."
2904 *
2905 * "Setting a signal action to SIG_DFL for a signal that is
2906 * pending and whose default action is to ignore the signal
2907 * (for example, SIGCHLD), shall cause the pending signal to
2908 * be discarded, whether or not it is blocked"
2909 */
2910 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2911 sigemptyset(&mask);
2912 sigaddset(&mask, sig);
2913 rm_from_queue_full(&mask, &t->signal->shared_pending);
2914 do {
2915 rm_from_queue_full(&mask, &t->pending);
2916 t = next_thread(t);
2917 } while (t != current);
2918 }
2919 }
2920
2921 spin_unlock_irq(¤t->sighand->siglock);
2922 return 0;
2923}
2924
2925int
2926do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2927{
2928 stack_t oss;
2929 int error;
2930
2931 oss.ss_sp = (void __user *) current->sas_ss_sp;
2932 oss.ss_size = current->sas_ss_size;
2933 oss.ss_flags = sas_ss_flags(sp);
2934
2935 if (uss) {
2936 void __user *ss_sp;
2937 size_t ss_size;
2938 int ss_flags;
2939
2940 error = -EFAULT;
2941 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
2942 goto out;
2943 error = __get_user(ss_sp, &uss->ss_sp) |
2944 __get_user(ss_flags, &uss->ss_flags) |
2945 __get_user(ss_size, &uss->ss_size);
2946 if (error)
2947 goto out;
2948
2949 error = -EPERM;
2950 if (on_sig_stack(sp))
2951 goto out;
2952
2953 error = -EINVAL;
2954 /*
2955 * Note - this code used to test ss_flags incorrectly:
2956 * old code may have been written using ss_flags==0
2957 * to mean ss_flags==SS_ONSTACK (as this was the only
2958 * way that worked) - this fix preserves that older
2959 * mechanism.
2960 */
2961 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2962 goto out;
2963
2964 if (ss_flags == SS_DISABLE) {
2965 ss_size = 0;
2966 ss_sp = NULL;
2967 } else {
2968 error = -ENOMEM;
2969 if (ss_size < MINSIGSTKSZ)
2970 goto out;
2971 }
2972
2973 current->sas_ss_sp = (unsigned long) ss_sp;
2974 current->sas_ss_size = ss_size;
2975 }
2976
2977 error = 0;
2978 if (uoss) {
2979 error = -EFAULT;
2980 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
2981 goto out;
2982 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
2983 __put_user(oss.ss_size, &uoss->ss_size) |
2984 __put_user(oss.ss_flags, &uoss->ss_flags);
2985 }
2986
2987out:
2988 return error;
2989}
2990
2991#ifdef __ARCH_WANT_SYS_SIGPENDING
2992
2993/**
2994 * sys_sigpending - examine pending signals
2995 * @set: where mask of pending signal is returned
2996 */
2997SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
2998{
2999 return do_sigpending(set, sizeof(*set));
3000}
3001
3002#endif
3003
3004#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3005/**
3006 * sys_sigprocmask - examine and change blocked signals
3007 * @how: whether to add, remove, or set signals
3008 * @nset: signals to add or remove (if non-null)
3009 * @oset: previous value of signal mask if non-null
3010 *
3011 * Some platforms have their own version with special arguments;
3012 * others support only sys_rt_sigprocmask.
3013 */
3014
3015SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3016 old_sigset_t __user *, oset)
3017{
3018 old_sigset_t old_set, new_set;
3019 sigset_t new_blocked;
3020
3021 old_set = current->blocked.sig[0];
3022
3023 if (nset) {
3024 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3025 return -EFAULT;
3026 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3027
3028 new_blocked = current->blocked;
3029
3030 switch (how) {
3031 case SIG_BLOCK:
3032 sigaddsetmask(&new_blocked, new_set);
3033 break;
3034 case SIG_UNBLOCK:
3035 sigdelsetmask(&new_blocked, new_set);
3036 break;
3037 case SIG_SETMASK:
3038 new_blocked.sig[0] = new_set;
3039 break;
3040 default:
3041 return -EINVAL;
3042 }
3043
3044 set_current_blocked(&new_blocked);
3045 }
3046
3047 if (oset) {
3048 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3049 return -EFAULT;
3050 }
3051
3052 return 0;
3053}
3054#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3055
3056#ifdef __ARCH_WANT_SYS_RT_SIGACTION
3057/**
3058 * sys_rt_sigaction - alter an action taken by a process
3059 * @sig: signal to be sent
3060 * @act: new sigaction
3061 * @oact: used to save the previous sigaction
3062 * @sigsetsize: size of sigset_t type
3063 */
3064SYSCALL_DEFINE4(rt_sigaction, int, sig,
3065 const struct sigaction __user *, act,
3066 struct sigaction __user *, oact,
3067 size_t, sigsetsize)
3068{
3069 struct k_sigaction new_sa, old_sa;
3070 int ret = -EINVAL;
3071
3072 /* XXX: Don't preclude handling different sized sigset_t's. */
3073 if (sigsetsize != sizeof(sigset_t))
3074 goto out;
3075
3076 if (act) {
3077 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3078 return -EFAULT;
3079 }
3080
3081 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3082
3083 if (!ret && oact) {
3084 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3085 return -EFAULT;
3086 }
3087out:
3088 return ret;
3089}
3090#endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3091
3092#ifdef __ARCH_WANT_SYS_SGETMASK
3093
3094/*
3095 * For backwards compatibility. Functionality superseded by sigprocmask.
3096 */
3097SYSCALL_DEFINE0(sgetmask)
3098{
3099 /* SMP safe */
3100 return current->blocked.sig[0];
3101}
3102
3103SYSCALL_DEFINE1(ssetmask, int, newmask)
3104{
3105 int old = current->blocked.sig[0];
3106 sigset_t newset;
3107
3108 siginitset(&newset, newmask & ~(sigmask(SIGKILL) | sigmask(SIGSTOP)));
3109 set_current_blocked(&newset);
3110
3111 return old;
3112}
3113#endif /* __ARCH_WANT_SGETMASK */
3114
3115#ifdef __ARCH_WANT_SYS_SIGNAL
3116/*
3117 * For backwards compatibility. Functionality superseded by sigaction.
3118 */
3119SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3120{
3121 struct k_sigaction new_sa, old_sa;
3122 int ret;
3123
3124 new_sa.sa.sa_handler = handler;
3125 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3126 sigemptyset(&new_sa.sa.sa_mask);
3127
3128 ret = do_sigaction(sig, &new_sa, &old_sa);
3129
3130 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3131}
3132#endif /* __ARCH_WANT_SYS_SIGNAL */
3133
3134#ifdef __ARCH_WANT_SYS_PAUSE
3135
3136SYSCALL_DEFINE0(pause)
3137{
3138 while (!signal_pending(current)) {
3139 current->state = TASK_INTERRUPTIBLE;
3140 schedule();
3141 }
3142 return -ERESTARTNOHAND;
3143}
3144
3145#endif
3146
3147#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3148/**
3149 * sys_rt_sigsuspend - replace the signal mask for a value with the
3150 * @unewset value until a signal is received
3151 * @unewset: new signal mask value
3152 * @sigsetsize: size of sigset_t type
3153 */
3154SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3155{
3156 sigset_t newset;
3157
3158 /* XXX: Don't preclude handling different sized sigset_t's. */
3159 if (sigsetsize != sizeof(sigset_t))
3160 return -EINVAL;
3161
3162 if (copy_from_user(&newset, unewset, sizeof(newset)))
3163 return -EFAULT;
3164 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
3165
3166 current->saved_sigmask = current->blocked;
3167 set_current_blocked(&newset);
3168
3169 current->state = TASK_INTERRUPTIBLE;
3170 schedule();
3171 set_restore_sigmask();
3172 return -ERESTARTNOHAND;
3173}
3174#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3175
3176__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3177{
3178 return NULL;
3179}
3180
3181void __init signals_init(void)
3182{
3183 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3184}
3185
3186#ifdef CONFIG_KGDB_KDB
3187#include <linux/kdb.h>
3188/*
3189 * kdb_send_sig_info - Allows kdb to send signals without exposing
3190 * signal internals. This function checks if the required locks are
3191 * available before calling the main signal code, to avoid kdb
3192 * deadlocks.
3193 */
3194void
3195kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3196{
3197 static struct task_struct *kdb_prev_t;
3198 int sig, new_t;
3199 if (!spin_trylock(&t->sighand->siglock)) {
3200 kdb_printf("Can't do kill command now.\n"
3201 "The sigmask lock is held somewhere else in "
3202 "kernel, try again later\n");
3203 return;
3204 }
3205 spin_unlock(&t->sighand->siglock);
3206 new_t = kdb_prev_t != t;
3207 kdb_prev_t = t;
3208 if (t->state != TASK_RUNNING && new_t) {
3209 kdb_printf("Process is not RUNNING, sending a signal from "
3210 "kdb risks deadlock\n"
3211 "on the run queue locks. "
3212 "The signal has _not_ been sent.\n"
3213 "Reissue the kill command if you want to risk "
3214 "the deadlock.\n");
3215 return;
3216 }
3217 sig = info->si_signo;
3218 if (send_sig_info(sig, info, t))
3219 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3220 sig, t->pid);
3221 else
3222 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3223}
3224#endif /* CONFIG_KGDB_KDB */