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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/mm.h>
17 #include <linux/sched/user.h>
18 #include <linux/sched/debug.h>
19 #include <linux/sched/task.h>
20 #include <linux/sched/task_stack.h>
21 #include <linux/sched/cputime.h>
22 #include <linux/fs.h>
23 #include <linux/tty.h>
24 #include <linux/binfmts.h>
25 #include <linux/coredump.h>
26 #include <linux/security.h>
27 #include <linux/syscalls.h>
28 #include <linux/ptrace.h>
29 #include <linux/signal.h>
30 #include <linux/signalfd.h>
31 #include <linux/ratelimit.h>
32 #include <linux/tracehook.h>
33 #include <linux/capability.h>
34 #include <linux/freezer.h>
35 #include <linux/pid_namespace.h>
36 #include <linux/nsproxy.h>
37 #include <linux/user_namespace.h>
38 #include <linux/uprobes.h>
39 #include <linux/compat.h>
40 #include <linux/cn_proc.h>
41 #include <linux/compiler.h>
42
43 #define CREATE_TRACE_POINTS
44 #include <trace/events/signal.h>
45
46 #include <asm/param.h>
47 #include <linux/uaccess.h>
48 #include <asm/unistd.h>
49 #include <asm/siginfo.h>
50 #include <asm/cacheflush.h>
51 #include "audit.h" /* audit_signal_info() */
52
53 /*
54 * SLAB caches for signal bits.
55 */
56
57 static struct kmem_cache *sigqueue_cachep;
58
59 int print_fatal_signals __read_mostly;
60
61 static void __user *sig_handler(struct task_struct *t, int sig)
62 {
63 return t->sighand->action[sig - 1].sa.sa_handler;
64 }
65
66 static int sig_handler_ignored(void __user *handler, int sig)
67 {
68 /* Is it explicitly or implicitly ignored? */
69 return handler == SIG_IGN ||
70 (handler == SIG_DFL && sig_kernel_ignore(sig));
71 }
72
73 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
74 {
75 void __user *handler;
76
77 handler = sig_handler(t, sig);
78
79 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
80 handler == SIG_DFL && !force)
81 return 1;
82
83 return sig_handler_ignored(handler, sig);
84 }
85
86 static int sig_ignored(struct task_struct *t, int sig, bool force)
87 {
88 /*
89 * Blocked signals are never ignored, since the
90 * signal handler may change by the time it is
91 * unblocked.
92 */
93 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
94 return 0;
95
96 if (!sig_task_ignored(t, sig, force))
97 return 0;
98
99 /*
100 * Tracers may want to know about even ignored signals.
101 */
102 return !t->ptrace;
103 }
104
105 /*
106 * Re-calculate pending state from the set of locally pending
107 * signals, globally pending signals, and blocked signals.
108 */
109 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
110 {
111 unsigned long ready;
112 long i;
113
114 switch (_NSIG_WORDS) {
115 default:
116 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
117 ready |= signal->sig[i] &~ blocked->sig[i];
118 break;
119
120 case 4: ready = signal->sig[3] &~ blocked->sig[3];
121 ready |= signal->sig[2] &~ blocked->sig[2];
122 ready |= signal->sig[1] &~ blocked->sig[1];
123 ready |= signal->sig[0] &~ blocked->sig[0];
124 break;
125
126 case 2: ready = signal->sig[1] &~ blocked->sig[1];
127 ready |= signal->sig[0] &~ blocked->sig[0];
128 break;
129
130 case 1: ready = signal->sig[0] &~ blocked->sig[0];
131 }
132 return ready != 0;
133 }
134
135 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
136
137 static int recalc_sigpending_tsk(struct task_struct *t)
138 {
139 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
140 PENDING(&t->pending, &t->blocked) ||
141 PENDING(&t->signal->shared_pending, &t->blocked)) {
142 set_tsk_thread_flag(t, TIF_SIGPENDING);
143 return 1;
144 }
145 /*
146 * We must never clear the flag in another thread, or in current
147 * when it's possible the current syscall is returning -ERESTART*.
148 * So we don't clear it here, and only callers who know they should do.
149 */
150 return 0;
151 }
152
153 /*
154 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
155 * This is superfluous when called on current, the wakeup is a harmless no-op.
156 */
157 void recalc_sigpending_and_wake(struct task_struct *t)
158 {
159 if (recalc_sigpending_tsk(t))
160 signal_wake_up(t, 0);
161 }
162
163 void recalc_sigpending(void)
164 {
165 if (!recalc_sigpending_tsk(current) && !freezing(current))
166 clear_thread_flag(TIF_SIGPENDING);
167
168 }
169
170 /* Given the mask, find the first available signal that should be serviced. */
171
172 #define SYNCHRONOUS_MASK \
173 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
174 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
175
176 int next_signal(struct sigpending *pending, sigset_t *mask)
177 {
178 unsigned long i, *s, *m, x;
179 int sig = 0;
180
181 s = pending->signal.sig;
182 m = mask->sig;
183
184 /*
185 * Handle the first word specially: it contains the
186 * synchronous signals that need to be dequeued first.
187 */
188 x = *s &~ *m;
189 if (x) {
190 if (x & SYNCHRONOUS_MASK)
191 x &= SYNCHRONOUS_MASK;
192 sig = ffz(~x) + 1;
193 return sig;
194 }
195
196 switch (_NSIG_WORDS) {
197 default:
198 for (i = 1; i < _NSIG_WORDS; ++i) {
199 x = *++s &~ *++m;
200 if (!x)
201 continue;
202 sig = ffz(~x) + i*_NSIG_BPW + 1;
203 break;
204 }
205 break;
206
207 case 2:
208 x = s[1] &~ m[1];
209 if (!x)
210 break;
211 sig = ffz(~x) + _NSIG_BPW + 1;
212 break;
213
214 case 1:
215 /* Nothing to do */
216 break;
217 }
218
219 return sig;
220 }
221
222 static inline void print_dropped_signal(int sig)
223 {
224 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
225
226 if (!print_fatal_signals)
227 return;
228
229 if (!__ratelimit(&ratelimit_state))
230 return;
231
232 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
233 current->comm, current->pid, sig);
234 }
235
236 /**
237 * task_set_jobctl_pending - set jobctl pending bits
238 * @task: target task
239 * @mask: pending bits to set
240 *
241 * Clear @mask from @task->jobctl. @mask must be subset of
242 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
243 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
244 * cleared. If @task is already being killed or exiting, this function
245 * becomes noop.
246 *
247 * CONTEXT:
248 * Must be called with @task->sighand->siglock held.
249 *
250 * RETURNS:
251 * %true if @mask is set, %false if made noop because @task was dying.
252 */
253 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
254 {
255 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
256 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
257 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
258
259 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
260 return false;
261
262 if (mask & JOBCTL_STOP_SIGMASK)
263 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
264
265 task->jobctl |= mask;
266 return true;
267 }
268
269 /**
270 * task_clear_jobctl_trapping - clear jobctl trapping bit
271 * @task: target task
272 *
273 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
274 * Clear it and wake up the ptracer. Note that we don't need any further
275 * locking. @task->siglock guarantees that @task->parent points to the
276 * ptracer.
277 *
278 * CONTEXT:
279 * Must be called with @task->sighand->siglock held.
280 */
281 void task_clear_jobctl_trapping(struct task_struct *task)
282 {
283 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
284 task->jobctl &= ~JOBCTL_TRAPPING;
285 smp_mb(); /* advised by wake_up_bit() */
286 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
287 }
288 }
289
290 /**
291 * task_clear_jobctl_pending - clear jobctl pending bits
292 * @task: target task
293 * @mask: pending bits to clear
294 *
295 * Clear @mask from @task->jobctl. @mask must be subset of
296 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
297 * STOP bits are cleared together.
298 *
299 * If clearing of @mask leaves no stop or trap pending, this function calls
300 * task_clear_jobctl_trapping().
301 *
302 * CONTEXT:
303 * Must be called with @task->sighand->siglock held.
304 */
305 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
306 {
307 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
308
309 if (mask & JOBCTL_STOP_PENDING)
310 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
311
312 task->jobctl &= ~mask;
313
314 if (!(task->jobctl & JOBCTL_PENDING_MASK))
315 task_clear_jobctl_trapping(task);
316 }
317
318 /**
319 * task_participate_group_stop - participate in a group stop
320 * @task: task participating in a group stop
321 *
322 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
323 * Group stop states are cleared and the group stop count is consumed if
324 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
325 * stop, the appropriate %SIGNAL_* flags are set.
326 *
327 * CONTEXT:
328 * Must be called with @task->sighand->siglock held.
329 *
330 * RETURNS:
331 * %true if group stop completion should be notified to the parent, %false
332 * otherwise.
333 */
334 static bool task_participate_group_stop(struct task_struct *task)
335 {
336 struct signal_struct *sig = task->signal;
337 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
338
339 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
340
341 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
342
343 if (!consume)
344 return false;
345
346 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
347 sig->group_stop_count--;
348
349 /*
350 * Tell the caller to notify completion iff we are entering into a
351 * fresh group stop. Read comment in do_signal_stop() for details.
352 */
353 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
354 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
355 return true;
356 }
357 return false;
358 }
359
360 /*
361 * allocate a new signal queue record
362 * - this may be called without locks if and only if t == current, otherwise an
363 * appropriate lock must be held to stop the target task from exiting
364 */
365 static struct sigqueue *
366 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
367 {
368 struct sigqueue *q = NULL;
369 struct user_struct *user;
370
371 /*
372 * Protect access to @t credentials. This can go away when all
373 * callers hold rcu read lock.
374 */
375 rcu_read_lock();
376 user = get_uid(__task_cred(t)->user);
377 atomic_inc(&user->sigpending);
378 rcu_read_unlock();
379
380 if (override_rlimit ||
381 atomic_read(&user->sigpending) <=
382 task_rlimit(t, RLIMIT_SIGPENDING)) {
383 q = kmem_cache_alloc(sigqueue_cachep, flags);
384 } else {
385 print_dropped_signal(sig);
386 }
387
388 if (unlikely(q == NULL)) {
389 atomic_dec(&user->sigpending);
390 free_uid(user);
391 } else {
392 INIT_LIST_HEAD(&q->list);
393 q->flags = 0;
394 q->user = user;
395 }
396
397 return q;
398 }
399
400 static void __sigqueue_free(struct sigqueue *q)
401 {
402 if (q->flags & SIGQUEUE_PREALLOC)
403 return;
404 atomic_dec(&q->user->sigpending);
405 free_uid(q->user);
406 kmem_cache_free(sigqueue_cachep, q);
407 }
408
409 void flush_sigqueue(struct sigpending *queue)
410 {
411 struct sigqueue *q;
412
413 sigemptyset(&queue->signal);
414 while (!list_empty(&queue->list)) {
415 q = list_entry(queue->list.next, struct sigqueue , list);
416 list_del_init(&q->list);
417 __sigqueue_free(q);
418 }
419 }
420
421 /*
422 * Flush all pending signals for this kthread.
423 */
424 void flush_signals(struct task_struct *t)
425 {
426 unsigned long flags;
427
428 spin_lock_irqsave(&t->sighand->siglock, flags);
429 clear_tsk_thread_flag(t, TIF_SIGPENDING);
430 flush_sigqueue(&t->pending);
431 flush_sigqueue(&t->signal->shared_pending);
432 spin_unlock_irqrestore(&t->sighand->siglock, flags);
433 }
434
435 #ifdef CONFIG_POSIX_TIMERS
436 static void __flush_itimer_signals(struct sigpending *pending)
437 {
438 sigset_t signal, retain;
439 struct sigqueue *q, *n;
440
441 signal = pending->signal;
442 sigemptyset(&retain);
443
444 list_for_each_entry_safe(q, n, &pending->list, list) {
445 int sig = q->info.si_signo;
446
447 if (likely(q->info.si_code != SI_TIMER)) {
448 sigaddset(&retain, sig);
449 } else {
450 sigdelset(&signal, sig);
451 list_del_init(&q->list);
452 __sigqueue_free(q);
453 }
454 }
455
456 sigorsets(&pending->signal, &signal, &retain);
457 }
458
459 void flush_itimer_signals(void)
460 {
461 struct task_struct *tsk = current;
462 unsigned long flags;
463
464 spin_lock_irqsave(&tsk->sighand->siglock, flags);
465 __flush_itimer_signals(&tsk->pending);
466 __flush_itimer_signals(&tsk->signal->shared_pending);
467 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
468 }
469 #endif
470
471 void ignore_signals(struct task_struct *t)
472 {
473 int i;
474
475 for (i = 0; i < _NSIG; ++i)
476 t->sighand->action[i].sa.sa_handler = SIG_IGN;
477
478 flush_signals(t);
479 }
480
481 /*
482 * Flush all handlers for a task.
483 */
484
485 void
486 flush_signal_handlers(struct task_struct *t, int force_default)
487 {
488 int i;
489 struct k_sigaction *ka = &t->sighand->action[0];
490 for (i = _NSIG ; i != 0 ; i--) {
491 if (force_default || ka->sa.sa_handler != SIG_IGN)
492 ka->sa.sa_handler = SIG_DFL;
493 ka->sa.sa_flags = 0;
494 #ifdef __ARCH_HAS_SA_RESTORER
495 ka->sa.sa_restorer = NULL;
496 #endif
497 sigemptyset(&ka->sa.sa_mask);
498 ka++;
499 }
500 }
501
502 int unhandled_signal(struct task_struct *tsk, int sig)
503 {
504 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
505 if (is_global_init(tsk))
506 return 1;
507 if (handler != SIG_IGN && handler != SIG_DFL)
508 return 0;
509 /* if ptraced, let the tracer determine */
510 return !tsk->ptrace;
511 }
512
513 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
514 {
515 struct sigqueue *q, *first = NULL;
516
517 /*
518 * Collect the siginfo appropriate to this signal. Check if
519 * there is another siginfo for the same signal.
520 */
521 list_for_each_entry(q, &list->list, list) {
522 if (q->info.si_signo == sig) {
523 if (first)
524 goto still_pending;
525 first = q;
526 }
527 }
528
529 sigdelset(&list->signal, sig);
530
531 if (first) {
532 still_pending:
533 list_del_init(&first->list);
534 copy_siginfo(info, &first->info);
535 __sigqueue_free(first);
536 } else {
537 /*
538 * Ok, it wasn't in the queue. This must be
539 * a fast-pathed signal or we must have been
540 * out of queue space. So zero out the info.
541 */
542 info->si_signo = sig;
543 info->si_errno = 0;
544 info->si_code = SI_USER;
545 info->si_pid = 0;
546 info->si_uid = 0;
547 }
548 }
549
550 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
551 siginfo_t *info)
552 {
553 int sig = next_signal(pending, mask);
554
555 if (sig)
556 collect_signal(sig, pending, info);
557 return sig;
558 }
559
560 /*
561 * Dequeue a signal and return the element to the caller, which is
562 * expected to free it.
563 *
564 * All callers have to hold the siglock.
565 */
566 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
567 {
568 int signr;
569
570 /* We only dequeue private signals from ourselves, we don't let
571 * signalfd steal them
572 */
573 signr = __dequeue_signal(&tsk->pending, mask, info);
574 if (!signr) {
575 signr = __dequeue_signal(&tsk->signal->shared_pending,
576 mask, info);
577 #ifdef CONFIG_POSIX_TIMERS
578 /*
579 * itimer signal ?
580 *
581 * itimers are process shared and we restart periodic
582 * itimers in the signal delivery path to prevent DoS
583 * attacks in the high resolution timer case. This is
584 * compliant with the old way of self-restarting
585 * itimers, as the SIGALRM is a legacy signal and only
586 * queued once. Changing the restart behaviour to
587 * restart the timer in the signal dequeue path is
588 * reducing the timer noise on heavy loaded !highres
589 * systems too.
590 */
591 if (unlikely(signr == SIGALRM)) {
592 struct hrtimer *tmr = &tsk->signal->real_timer;
593
594 if (!hrtimer_is_queued(tmr) &&
595 tsk->signal->it_real_incr != 0) {
596 hrtimer_forward(tmr, tmr->base->get_time(),
597 tsk->signal->it_real_incr);
598 hrtimer_restart(tmr);
599 }
600 }
601 #endif
602 }
603
604 recalc_sigpending();
605 if (!signr)
606 return 0;
607
608 if (unlikely(sig_kernel_stop(signr))) {
609 /*
610 * Set a marker that we have dequeued a stop signal. Our
611 * caller might release the siglock and then the pending
612 * stop signal it is about to process is no longer in the
613 * pending bitmasks, but must still be cleared by a SIGCONT
614 * (and overruled by a SIGKILL). So those cases clear this
615 * shared flag after we've set it. Note that this flag may
616 * remain set after the signal we return is ignored or
617 * handled. That doesn't matter because its only purpose
618 * is to alert stop-signal processing code when another
619 * processor has come along and cleared the flag.
620 */
621 current->jobctl |= JOBCTL_STOP_DEQUEUED;
622 }
623 #ifdef CONFIG_POSIX_TIMERS
624 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
625 /*
626 * Release the siglock to ensure proper locking order
627 * of timer locks outside of siglocks. Note, we leave
628 * irqs disabled here, since the posix-timers code is
629 * about to disable them again anyway.
630 */
631 spin_unlock(&tsk->sighand->siglock);
632 do_schedule_next_timer(info);
633 spin_lock(&tsk->sighand->siglock);
634 }
635 #endif
636 return signr;
637 }
638
639 /*
640 * Tell a process that it has a new active signal..
641 *
642 * NOTE! we rely on the previous spin_lock to
643 * lock interrupts for us! We can only be called with
644 * "siglock" held, and the local interrupt must
645 * have been disabled when that got acquired!
646 *
647 * No need to set need_resched since signal event passing
648 * goes through ->blocked
649 */
650 void signal_wake_up_state(struct task_struct *t, unsigned int state)
651 {
652 set_tsk_thread_flag(t, TIF_SIGPENDING);
653 /*
654 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
655 * case. We don't check t->state here because there is a race with it
656 * executing another processor and just now entering stopped state.
657 * By using wake_up_state, we ensure the process will wake up and
658 * handle its death signal.
659 */
660 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
661 kick_process(t);
662 }
663
664 /*
665 * Remove signals in mask from the pending set and queue.
666 * Returns 1 if any signals were found.
667 *
668 * All callers must be holding the siglock.
669 */
670 static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
671 {
672 struct sigqueue *q, *n;
673 sigset_t m;
674
675 sigandsets(&m, mask, &s->signal);
676 if (sigisemptyset(&m))
677 return 0;
678
679 sigandnsets(&s->signal, &s->signal, mask);
680 list_for_each_entry_safe(q, n, &s->list, list) {
681 if (sigismember(mask, q->info.si_signo)) {
682 list_del_init(&q->list);
683 __sigqueue_free(q);
684 }
685 }
686 return 1;
687 }
688
689 static inline int is_si_special(const struct siginfo *info)
690 {
691 return info <= SEND_SIG_FORCED;
692 }
693
694 static inline bool si_fromuser(const struct siginfo *info)
695 {
696 return info == SEND_SIG_NOINFO ||
697 (!is_si_special(info) && SI_FROMUSER(info));
698 }
699
700 /*
701 * called with RCU read lock from check_kill_permission()
702 */
703 static int kill_ok_by_cred(struct task_struct *t)
704 {
705 const struct cred *cred = current_cred();
706 const struct cred *tcred = __task_cred(t);
707
708 if (uid_eq(cred->euid, tcred->suid) ||
709 uid_eq(cred->euid, tcred->uid) ||
710 uid_eq(cred->uid, tcred->suid) ||
711 uid_eq(cred->uid, tcred->uid))
712 return 1;
713
714 if (ns_capable(tcred->user_ns, CAP_KILL))
715 return 1;
716
717 return 0;
718 }
719
720 /*
721 * Bad permissions for sending the signal
722 * - the caller must hold the RCU read lock
723 */
724 static int check_kill_permission(int sig, struct siginfo *info,
725 struct task_struct *t)
726 {
727 struct pid *sid;
728 int error;
729
730 if (!valid_signal(sig))
731 return -EINVAL;
732
733 if (!si_fromuser(info))
734 return 0;
735
736 error = audit_signal_info(sig, t); /* Let audit system see the signal */
737 if (error)
738 return error;
739
740 if (!same_thread_group(current, t) &&
741 !kill_ok_by_cred(t)) {
742 switch (sig) {
743 case SIGCONT:
744 sid = task_session(t);
745 /*
746 * We don't return the error if sid == NULL. The
747 * task was unhashed, the caller must notice this.
748 */
749 if (!sid || sid == task_session(current))
750 break;
751 default:
752 return -EPERM;
753 }
754 }
755
756 return security_task_kill(t, info, sig, 0);
757 }
758
759 /**
760 * ptrace_trap_notify - schedule trap to notify ptracer
761 * @t: tracee wanting to notify tracer
762 *
763 * This function schedules sticky ptrace trap which is cleared on the next
764 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
765 * ptracer.
766 *
767 * If @t is running, STOP trap will be taken. If trapped for STOP and
768 * ptracer is listening for events, tracee is woken up so that it can
769 * re-trap for the new event. If trapped otherwise, STOP trap will be
770 * eventually taken without returning to userland after the existing traps
771 * are finished by PTRACE_CONT.
772 *
773 * CONTEXT:
774 * Must be called with @task->sighand->siglock held.
775 */
776 static void ptrace_trap_notify(struct task_struct *t)
777 {
778 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
779 assert_spin_locked(&t->sighand->siglock);
780
781 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
782 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
783 }
784
785 /*
786 * Handle magic process-wide effects of stop/continue signals. Unlike
787 * the signal actions, these happen immediately at signal-generation
788 * time regardless of blocking, ignoring, or handling. This does the
789 * actual continuing for SIGCONT, but not the actual stopping for stop
790 * signals. The process stop is done as a signal action for SIG_DFL.
791 *
792 * Returns true if the signal should be actually delivered, otherwise
793 * it should be dropped.
794 */
795 static bool prepare_signal(int sig, struct task_struct *p, bool force)
796 {
797 struct signal_struct *signal = p->signal;
798 struct task_struct *t;
799 sigset_t flush;
800
801 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
802 if (!(signal->flags & SIGNAL_GROUP_EXIT))
803 return sig == SIGKILL;
804 /*
805 * The process is in the middle of dying, nothing to do.
806 */
807 } else if (sig_kernel_stop(sig)) {
808 /*
809 * This is a stop signal. Remove SIGCONT from all queues.
810 */
811 siginitset(&flush, sigmask(SIGCONT));
812 flush_sigqueue_mask(&flush, &signal->shared_pending);
813 for_each_thread(p, t)
814 flush_sigqueue_mask(&flush, &t->pending);
815 } else if (sig == SIGCONT) {
816 unsigned int why;
817 /*
818 * Remove all stop signals from all queues, wake all threads.
819 */
820 siginitset(&flush, SIG_KERNEL_STOP_MASK);
821 flush_sigqueue_mask(&flush, &signal->shared_pending);
822 for_each_thread(p, t) {
823 flush_sigqueue_mask(&flush, &t->pending);
824 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
825 if (likely(!(t->ptrace & PT_SEIZED)))
826 wake_up_state(t, __TASK_STOPPED);
827 else
828 ptrace_trap_notify(t);
829 }
830
831 /*
832 * Notify the parent with CLD_CONTINUED if we were stopped.
833 *
834 * If we were in the middle of a group stop, we pretend it
835 * was already finished, and then continued. Since SIGCHLD
836 * doesn't queue we report only CLD_STOPPED, as if the next
837 * CLD_CONTINUED was dropped.
838 */
839 why = 0;
840 if (signal->flags & SIGNAL_STOP_STOPPED)
841 why |= SIGNAL_CLD_CONTINUED;
842 else if (signal->group_stop_count)
843 why |= SIGNAL_CLD_STOPPED;
844
845 if (why) {
846 /*
847 * The first thread which returns from do_signal_stop()
848 * will take ->siglock, notice SIGNAL_CLD_MASK, and
849 * notify its parent. See get_signal_to_deliver().
850 */
851 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
852 signal->group_stop_count = 0;
853 signal->group_exit_code = 0;
854 }
855 }
856
857 return !sig_ignored(p, sig, force);
858 }
859
860 /*
861 * Test if P wants to take SIG. After we've checked all threads with this,
862 * it's equivalent to finding no threads not blocking SIG. Any threads not
863 * blocking SIG were ruled out because they are not running and already
864 * have pending signals. Such threads will dequeue from the shared queue
865 * as soon as they're available, so putting the signal on the shared queue
866 * will be equivalent to sending it to one such thread.
867 */
868 static inline int wants_signal(int sig, struct task_struct *p)
869 {
870 if (sigismember(&p->blocked, sig))
871 return 0;
872 if (p->flags & PF_EXITING)
873 return 0;
874 if (sig == SIGKILL)
875 return 1;
876 if (task_is_stopped_or_traced(p))
877 return 0;
878 return task_curr(p) || !signal_pending(p);
879 }
880
881 static void complete_signal(int sig, struct task_struct *p, int group)
882 {
883 struct signal_struct *signal = p->signal;
884 struct task_struct *t;
885
886 /*
887 * Now find a thread we can wake up to take the signal off the queue.
888 *
889 * If the main thread wants the signal, it gets first crack.
890 * Probably the least surprising to the average bear.
891 */
892 if (wants_signal(sig, p))
893 t = p;
894 else if (!group || thread_group_empty(p))
895 /*
896 * There is just one thread and it does not need to be woken.
897 * It will dequeue unblocked signals before it runs again.
898 */
899 return;
900 else {
901 /*
902 * Otherwise try to find a suitable thread.
903 */
904 t = signal->curr_target;
905 while (!wants_signal(sig, t)) {
906 t = next_thread(t);
907 if (t == signal->curr_target)
908 /*
909 * No thread needs to be woken.
910 * Any eligible threads will see
911 * the signal in the queue soon.
912 */
913 return;
914 }
915 signal->curr_target = t;
916 }
917
918 /*
919 * Found a killable thread. If the signal will be fatal,
920 * then start taking the whole group down immediately.
921 */
922 if (sig_fatal(p, sig) &&
923 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
924 !sigismember(&t->real_blocked, sig) &&
925 (sig == SIGKILL || !t->ptrace)) {
926 /*
927 * This signal will be fatal to the whole group.
928 */
929 if (!sig_kernel_coredump(sig)) {
930 /*
931 * Start a group exit and wake everybody up.
932 * This way we don't have other threads
933 * running and doing things after a slower
934 * thread has the fatal signal pending.
935 */
936 signal->flags = SIGNAL_GROUP_EXIT;
937 signal->group_exit_code = sig;
938 signal->group_stop_count = 0;
939 t = p;
940 do {
941 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
942 sigaddset(&t->pending.signal, SIGKILL);
943 signal_wake_up(t, 1);
944 } while_each_thread(p, t);
945 return;
946 }
947 }
948
949 /*
950 * The signal is already in the shared-pending queue.
951 * Tell the chosen thread to wake up and dequeue it.
952 */
953 signal_wake_up(t, sig == SIGKILL);
954 return;
955 }
956
957 static inline int legacy_queue(struct sigpending *signals, int sig)
958 {
959 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
960 }
961
962 #ifdef CONFIG_USER_NS
963 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
964 {
965 if (current_user_ns() == task_cred_xxx(t, user_ns))
966 return;
967
968 if (SI_FROMKERNEL(info))
969 return;
970
971 rcu_read_lock();
972 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
973 make_kuid(current_user_ns(), info->si_uid));
974 rcu_read_unlock();
975 }
976 #else
977 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
978 {
979 return;
980 }
981 #endif
982
983 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
984 int group, int from_ancestor_ns)
985 {
986 struct sigpending *pending;
987 struct sigqueue *q;
988 int override_rlimit;
989 int ret = 0, result;
990
991 assert_spin_locked(&t->sighand->siglock);
992
993 result = TRACE_SIGNAL_IGNORED;
994 if (!prepare_signal(sig, t,
995 from_ancestor_ns || (info == SEND_SIG_FORCED)))
996 goto ret;
997
998 pending = group ? &t->signal->shared_pending : &t->pending;
999 /*
1000 * Short-circuit ignored signals and support queuing
1001 * exactly one non-rt signal, so that we can get more
1002 * detailed information about the cause of the signal.
1003 */
1004 result = TRACE_SIGNAL_ALREADY_PENDING;
1005 if (legacy_queue(pending, sig))
1006 goto ret;
1007
1008 result = TRACE_SIGNAL_DELIVERED;
1009 /*
1010 * fast-pathed signals for kernel-internal things like SIGSTOP
1011 * or SIGKILL.
1012 */
1013 if (info == SEND_SIG_FORCED)
1014 goto out_set;
1015
1016 /*
1017 * Real-time signals must be queued if sent by sigqueue, or
1018 * some other real-time mechanism. It is implementation
1019 * defined whether kill() does so. We attempt to do so, on
1020 * the principle of least surprise, but since kill is not
1021 * allowed to fail with EAGAIN when low on memory we just
1022 * make sure at least one signal gets delivered and don't
1023 * pass on the info struct.
1024 */
1025 if (sig < SIGRTMIN)
1026 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1027 else
1028 override_rlimit = 0;
1029
1030 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1031 override_rlimit);
1032 if (q) {
1033 list_add_tail(&q->list, &pending->list);
1034 switch ((unsigned long) info) {
1035 case (unsigned long) SEND_SIG_NOINFO:
1036 q->info.si_signo = sig;
1037 q->info.si_errno = 0;
1038 q->info.si_code = SI_USER;
1039 q->info.si_pid = task_tgid_nr_ns(current,
1040 task_active_pid_ns(t));
1041 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1042 break;
1043 case (unsigned long) SEND_SIG_PRIV:
1044 q->info.si_signo = sig;
1045 q->info.si_errno = 0;
1046 q->info.si_code = SI_KERNEL;
1047 q->info.si_pid = 0;
1048 q->info.si_uid = 0;
1049 break;
1050 default:
1051 copy_siginfo(&q->info, info);
1052 if (from_ancestor_ns)
1053 q->info.si_pid = 0;
1054 break;
1055 }
1056
1057 userns_fixup_signal_uid(&q->info, t);
1058
1059 } else if (!is_si_special(info)) {
1060 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1061 /*
1062 * Queue overflow, abort. We may abort if the
1063 * signal was rt and sent by user using something
1064 * other than kill().
1065 */
1066 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1067 ret = -EAGAIN;
1068 goto ret;
1069 } else {
1070 /*
1071 * This is a silent loss of information. We still
1072 * send the signal, but the *info bits are lost.
1073 */
1074 result = TRACE_SIGNAL_LOSE_INFO;
1075 }
1076 }
1077
1078 out_set:
1079 signalfd_notify(t, sig);
1080 sigaddset(&pending->signal, sig);
1081 complete_signal(sig, t, group);
1082 ret:
1083 trace_signal_generate(sig, info, t, group, result);
1084 return ret;
1085 }
1086
1087 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1088 int group)
1089 {
1090 int from_ancestor_ns = 0;
1091
1092 #ifdef CONFIG_PID_NS
1093 from_ancestor_ns = si_fromuser(info) &&
1094 !task_pid_nr_ns(current, task_active_pid_ns(t));
1095 #endif
1096
1097 return __send_signal(sig, info, t, group, from_ancestor_ns);
1098 }
1099
1100 static void print_fatal_signal(int signr)
1101 {
1102 struct pt_regs *regs = signal_pt_regs();
1103 pr_info("potentially unexpected fatal signal %d.\n", signr);
1104
1105 #if defined(__i386__) && !defined(__arch_um__)
1106 pr_info("code at %08lx: ", regs->ip);
1107 {
1108 int i;
1109 for (i = 0; i < 16; i++) {
1110 unsigned char insn;
1111
1112 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1113 break;
1114 pr_cont("%02x ", insn);
1115 }
1116 }
1117 pr_cont("\n");
1118 #endif
1119 preempt_disable();
1120 show_regs(regs);
1121 preempt_enable();
1122 }
1123
1124 static int __init setup_print_fatal_signals(char *str)
1125 {
1126 get_option (&str, &print_fatal_signals);
1127
1128 return 1;
1129 }
1130
1131 __setup("print-fatal-signals=", setup_print_fatal_signals);
1132
1133 int
1134 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1135 {
1136 return send_signal(sig, info, p, 1);
1137 }
1138
1139 static int
1140 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1141 {
1142 return send_signal(sig, info, t, 0);
1143 }
1144
1145 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1146 bool group)
1147 {
1148 unsigned long flags;
1149 int ret = -ESRCH;
1150
1151 if (lock_task_sighand(p, &flags)) {
1152 ret = send_signal(sig, info, p, group);
1153 unlock_task_sighand(p, &flags);
1154 }
1155
1156 return ret;
1157 }
1158
1159 /*
1160 * Force a signal that the process can't ignore: if necessary
1161 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1162 *
1163 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1164 * since we do not want to have a signal handler that was blocked
1165 * be invoked when user space had explicitly blocked it.
1166 *
1167 * We don't want to have recursive SIGSEGV's etc, for example,
1168 * that is why we also clear SIGNAL_UNKILLABLE.
1169 */
1170 int
1171 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1172 {
1173 unsigned long int flags;
1174 int ret, blocked, ignored;
1175 struct k_sigaction *action;
1176
1177 spin_lock_irqsave(&t->sighand->siglock, flags);
1178 action = &t->sighand->action[sig-1];
1179 ignored = action->sa.sa_handler == SIG_IGN;
1180 blocked = sigismember(&t->blocked, sig);
1181 if (blocked || ignored) {
1182 action->sa.sa_handler = SIG_DFL;
1183 if (blocked) {
1184 sigdelset(&t->blocked, sig);
1185 recalc_sigpending_and_wake(t);
1186 }
1187 }
1188 if (action->sa.sa_handler == SIG_DFL)
1189 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1190 ret = specific_send_sig_info(sig, info, t);
1191 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1192
1193 return ret;
1194 }
1195
1196 /*
1197 * Nuke all other threads in the group.
1198 */
1199 int zap_other_threads(struct task_struct *p)
1200 {
1201 struct task_struct *t = p;
1202 int count = 0;
1203
1204 p->signal->group_stop_count = 0;
1205
1206 while_each_thread(p, t) {
1207 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1208 count++;
1209
1210 /* Don't bother with already dead threads */
1211 if (t->exit_state)
1212 continue;
1213 sigaddset(&t->pending.signal, SIGKILL);
1214 signal_wake_up(t, 1);
1215 }
1216
1217 return count;
1218 }
1219
1220 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1221 unsigned long *flags)
1222 {
1223 struct sighand_struct *sighand;
1224
1225 for (;;) {
1226 /*
1227 * Disable interrupts early to avoid deadlocks.
1228 * See rcu_read_unlock() comment header for details.
1229 */
1230 local_irq_save(*flags);
1231 rcu_read_lock();
1232 sighand = rcu_dereference(tsk->sighand);
1233 if (unlikely(sighand == NULL)) {
1234 rcu_read_unlock();
1235 local_irq_restore(*flags);
1236 break;
1237 }
1238 /*
1239 * This sighand can be already freed and even reused, but
1240 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1241 * initializes ->siglock: this slab can't go away, it has
1242 * the same object type, ->siglock can't be reinitialized.
1243 *
1244 * We need to ensure that tsk->sighand is still the same
1245 * after we take the lock, we can race with de_thread() or
1246 * __exit_signal(). In the latter case the next iteration
1247 * must see ->sighand == NULL.
1248 */
1249 spin_lock(&sighand->siglock);
1250 if (likely(sighand == tsk->sighand)) {
1251 rcu_read_unlock();
1252 break;
1253 }
1254 spin_unlock(&sighand->siglock);
1255 rcu_read_unlock();
1256 local_irq_restore(*flags);
1257 }
1258
1259 return sighand;
1260 }
1261
1262 /*
1263 * send signal info to all the members of a group
1264 */
1265 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1266 {
1267 int ret;
1268
1269 rcu_read_lock();
1270 ret = check_kill_permission(sig, info, p);
1271 rcu_read_unlock();
1272
1273 if (!ret && sig)
1274 ret = do_send_sig_info(sig, info, p, true);
1275
1276 return ret;
1277 }
1278
1279 /*
1280 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1281 * control characters do (^C, ^Z etc)
1282 * - the caller must hold at least a readlock on tasklist_lock
1283 */
1284 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1285 {
1286 struct task_struct *p = NULL;
1287 int retval, success;
1288
1289 success = 0;
1290 retval = -ESRCH;
1291 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1292 int err = group_send_sig_info(sig, info, p);
1293 success |= !err;
1294 retval = err;
1295 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1296 return success ? 0 : retval;
1297 }
1298
1299 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1300 {
1301 int error = -ESRCH;
1302 struct task_struct *p;
1303
1304 for (;;) {
1305 rcu_read_lock();
1306 p = pid_task(pid, PIDTYPE_PID);
1307 if (p)
1308 error = group_send_sig_info(sig, info, p);
1309 rcu_read_unlock();
1310 if (likely(!p || error != -ESRCH))
1311 return error;
1312
1313 /*
1314 * The task was unhashed in between, try again. If it
1315 * is dead, pid_task() will return NULL, if we race with
1316 * de_thread() it will find the new leader.
1317 */
1318 }
1319 }
1320
1321 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1322 {
1323 int error;
1324 rcu_read_lock();
1325 error = kill_pid_info(sig, info, find_vpid(pid));
1326 rcu_read_unlock();
1327 return error;
1328 }
1329
1330 static int kill_as_cred_perm(const struct cred *cred,
1331 struct task_struct *target)
1332 {
1333 const struct cred *pcred = __task_cred(target);
1334 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1335 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1336 return 0;
1337 return 1;
1338 }
1339
1340 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1341 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1342 const struct cred *cred, u32 secid)
1343 {
1344 int ret = -EINVAL;
1345 struct task_struct *p;
1346 unsigned long flags;
1347
1348 if (!valid_signal(sig))
1349 return ret;
1350
1351 rcu_read_lock();
1352 p = pid_task(pid, PIDTYPE_PID);
1353 if (!p) {
1354 ret = -ESRCH;
1355 goto out_unlock;
1356 }
1357 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1358 ret = -EPERM;
1359 goto out_unlock;
1360 }
1361 ret = security_task_kill(p, info, sig, secid);
1362 if (ret)
1363 goto out_unlock;
1364
1365 if (sig) {
1366 if (lock_task_sighand(p, &flags)) {
1367 ret = __send_signal(sig, info, p, 1, 0);
1368 unlock_task_sighand(p, &flags);
1369 } else
1370 ret = -ESRCH;
1371 }
1372 out_unlock:
1373 rcu_read_unlock();
1374 return ret;
1375 }
1376 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1377
1378 /*
1379 * kill_something_info() interprets pid in interesting ways just like kill(2).
1380 *
1381 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1382 * is probably wrong. Should make it like BSD or SYSV.
1383 */
1384
1385 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1386 {
1387 int ret;
1388
1389 if (pid > 0) {
1390 rcu_read_lock();
1391 ret = kill_pid_info(sig, info, find_vpid(pid));
1392 rcu_read_unlock();
1393 return ret;
1394 }
1395
1396 read_lock(&tasklist_lock);
1397 if (pid != -1) {
1398 ret = __kill_pgrp_info(sig, info,
1399 pid ? find_vpid(-pid) : task_pgrp(current));
1400 } else {
1401 int retval = 0, count = 0;
1402 struct task_struct * p;
1403
1404 for_each_process(p) {
1405 if (task_pid_vnr(p) > 1 &&
1406 !same_thread_group(p, current)) {
1407 int err = group_send_sig_info(sig, info, p);
1408 ++count;
1409 if (err != -EPERM)
1410 retval = err;
1411 }
1412 }
1413 ret = count ? retval : -ESRCH;
1414 }
1415 read_unlock(&tasklist_lock);
1416
1417 return ret;
1418 }
1419
1420 /*
1421 * These are for backward compatibility with the rest of the kernel source.
1422 */
1423
1424 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1425 {
1426 /*
1427 * Make sure legacy kernel users don't send in bad values
1428 * (normal paths check this in check_kill_permission).
1429 */
1430 if (!valid_signal(sig))
1431 return -EINVAL;
1432
1433 return do_send_sig_info(sig, info, p, false);
1434 }
1435
1436 #define __si_special(priv) \
1437 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1438
1439 int
1440 send_sig(int sig, struct task_struct *p, int priv)
1441 {
1442 return send_sig_info(sig, __si_special(priv), p);
1443 }
1444
1445 void
1446 force_sig(int sig, struct task_struct *p)
1447 {
1448 force_sig_info(sig, SEND_SIG_PRIV, p);
1449 }
1450
1451 /*
1452 * When things go south during signal handling, we
1453 * will force a SIGSEGV. And if the signal that caused
1454 * the problem was already a SIGSEGV, we'll want to
1455 * make sure we don't even try to deliver the signal..
1456 */
1457 int
1458 force_sigsegv(int sig, struct task_struct *p)
1459 {
1460 if (sig == SIGSEGV) {
1461 unsigned long flags;
1462 spin_lock_irqsave(&p->sighand->siglock, flags);
1463 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1464 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1465 }
1466 force_sig(SIGSEGV, p);
1467 return 0;
1468 }
1469
1470 int kill_pgrp(struct pid *pid, int sig, int priv)
1471 {
1472 int ret;
1473
1474 read_lock(&tasklist_lock);
1475 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1476 read_unlock(&tasklist_lock);
1477
1478 return ret;
1479 }
1480 EXPORT_SYMBOL(kill_pgrp);
1481
1482 int kill_pid(struct pid *pid, int sig, int priv)
1483 {
1484 return kill_pid_info(sig, __si_special(priv), pid);
1485 }
1486 EXPORT_SYMBOL(kill_pid);
1487
1488 /*
1489 * These functions support sending signals using preallocated sigqueue
1490 * structures. This is needed "because realtime applications cannot
1491 * afford to lose notifications of asynchronous events, like timer
1492 * expirations or I/O completions". In the case of POSIX Timers
1493 * we allocate the sigqueue structure from the timer_create. If this
1494 * allocation fails we are able to report the failure to the application
1495 * with an EAGAIN error.
1496 */
1497 struct sigqueue *sigqueue_alloc(void)
1498 {
1499 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1500
1501 if (q)
1502 q->flags |= SIGQUEUE_PREALLOC;
1503
1504 return q;
1505 }
1506
1507 void sigqueue_free(struct sigqueue *q)
1508 {
1509 unsigned long flags;
1510 spinlock_t *lock = &current->sighand->siglock;
1511
1512 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1513 /*
1514 * We must hold ->siglock while testing q->list
1515 * to serialize with collect_signal() or with
1516 * __exit_signal()->flush_sigqueue().
1517 */
1518 spin_lock_irqsave(lock, flags);
1519 q->flags &= ~SIGQUEUE_PREALLOC;
1520 /*
1521 * If it is queued it will be freed when dequeued,
1522 * like the "regular" sigqueue.
1523 */
1524 if (!list_empty(&q->list))
1525 q = NULL;
1526 spin_unlock_irqrestore(lock, flags);
1527
1528 if (q)
1529 __sigqueue_free(q);
1530 }
1531
1532 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1533 {
1534 int sig = q->info.si_signo;
1535 struct sigpending *pending;
1536 unsigned long flags;
1537 int ret, result;
1538
1539 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1540
1541 ret = -1;
1542 if (!likely(lock_task_sighand(t, &flags)))
1543 goto ret;
1544
1545 ret = 1; /* the signal is ignored */
1546 result = TRACE_SIGNAL_IGNORED;
1547 if (!prepare_signal(sig, t, false))
1548 goto out;
1549
1550 ret = 0;
1551 if (unlikely(!list_empty(&q->list))) {
1552 /*
1553 * If an SI_TIMER entry is already queue just increment
1554 * the overrun count.
1555 */
1556 BUG_ON(q->info.si_code != SI_TIMER);
1557 q->info.si_overrun++;
1558 result = TRACE_SIGNAL_ALREADY_PENDING;
1559 goto out;
1560 }
1561 q->info.si_overrun = 0;
1562
1563 signalfd_notify(t, sig);
1564 pending = group ? &t->signal->shared_pending : &t->pending;
1565 list_add_tail(&q->list, &pending->list);
1566 sigaddset(&pending->signal, sig);
1567 complete_signal(sig, t, group);
1568 result = TRACE_SIGNAL_DELIVERED;
1569 out:
1570 trace_signal_generate(sig, &q->info, t, group, result);
1571 unlock_task_sighand(t, &flags);
1572 ret:
1573 return ret;
1574 }
1575
1576 /*
1577 * Let a parent know about the death of a child.
1578 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1579 *
1580 * Returns true if our parent ignored us and so we've switched to
1581 * self-reaping.
1582 */
1583 bool do_notify_parent(struct task_struct *tsk, int sig)
1584 {
1585 struct siginfo info;
1586 unsigned long flags;
1587 struct sighand_struct *psig;
1588 bool autoreap = false;
1589 u64 utime, stime;
1590
1591 BUG_ON(sig == -1);
1592
1593 /* do_notify_parent_cldstop should have been called instead. */
1594 BUG_ON(task_is_stopped_or_traced(tsk));
1595
1596 BUG_ON(!tsk->ptrace &&
1597 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1598
1599 if (sig != SIGCHLD) {
1600 /*
1601 * This is only possible if parent == real_parent.
1602 * Check if it has changed security domain.
1603 */
1604 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1605 sig = SIGCHLD;
1606 }
1607
1608 info.si_signo = sig;
1609 info.si_errno = 0;
1610 /*
1611 * We are under tasklist_lock here so our parent is tied to
1612 * us and cannot change.
1613 *
1614 * task_active_pid_ns will always return the same pid namespace
1615 * until a task passes through release_task.
1616 *
1617 * write_lock() currently calls preempt_disable() which is the
1618 * same as rcu_read_lock(), but according to Oleg, this is not
1619 * correct to rely on this
1620 */
1621 rcu_read_lock();
1622 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1623 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1624 task_uid(tsk));
1625 rcu_read_unlock();
1626
1627 task_cputime(tsk, &utime, &stime);
1628 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1629 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1630
1631 info.si_status = tsk->exit_code & 0x7f;
1632 if (tsk->exit_code & 0x80)
1633 info.si_code = CLD_DUMPED;
1634 else if (tsk->exit_code & 0x7f)
1635 info.si_code = CLD_KILLED;
1636 else {
1637 info.si_code = CLD_EXITED;
1638 info.si_status = tsk->exit_code >> 8;
1639 }
1640
1641 psig = tsk->parent->sighand;
1642 spin_lock_irqsave(&psig->siglock, flags);
1643 if (!tsk->ptrace && sig == SIGCHLD &&
1644 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1645 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1646 /*
1647 * We are exiting and our parent doesn't care. POSIX.1
1648 * defines special semantics for setting SIGCHLD to SIG_IGN
1649 * or setting the SA_NOCLDWAIT flag: we should be reaped
1650 * automatically and not left for our parent's wait4 call.
1651 * Rather than having the parent do it as a magic kind of
1652 * signal handler, we just set this to tell do_exit that we
1653 * can be cleaned up without becoming a zombie. Note that
1654 * we still call __wake_up_parent in this case, because a
1655 * blocked sys_wait4 might now return -ECHILD.
1656 *
1657 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1658 * is implementation-defined: we do (if you don't want
1659 * it, just use SIG_IGN instead).
1660 */
1661 autoreap = true;
1662 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1663 sig = 0;
1664 }
1665 if (valid_signal(sig) && sig)
1666 __group_send_sig_info(sig, &info, tsk->parent);
1667 __wake_up_parent(tsk, tsk->parent);
1668 spin_unlock_irqrestore(&psig->siglock, flags);
1669
1670 return autoreap;
1671 }
1672
1673 /**
1674 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1675 * @tsk: task reporting the state change
1676 * @for_ptracer: the notification is for ptracer
1677 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1678 *
1679 * Notify @tsk's parent that the stopped/continued state has changed. If
1680 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1681 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1682 *
1683 * CONTEXT:
1684 * Must be called with tasklist_lock at least read locked.
1685 */
1686 static void do_notify_parent_cldstop(struct task_struct *tsk,
1687 bool for_ptracer, int why)
1688 {
1689 struct siginfo info;
1690 unsigned long flags;
1691 struct task_struct *parent;
1692 struct sighand_struct *sighand;
1693 u64 utime, stime;
1694
1695 if (for_ptracer) {
1696 parent = tsk->parent;
1697 } else {
1698 tsk = tsk->group_leader;
1699 parent = tsk->real_parent;
1700 }
1701
1702 info.si_signo = SIGCHLD;
1703 info.si_errno = 0;
1704 /*
1705 * see comment in do_notify_parent() about the following 4 lines
1706 */
1707 rcu_read_lock();
1708 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1709 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1710 rcu_read_unlock();
1711
1712 task_cputime(tsk, &utime, &stime);
1713 info.si_utime = nsec_to_clock_t(utime);
1714 info.si_stime = nsec_to_clock_t(stime);
1715
1716 info.si_code = why;
1717 switch (why) {
1718 case CLD_CONTINUED:
1719 info.si_status = SIGCONT;
1720 break;
1721 case CLD_STOPPED:
1722 info.si_status = tsk->signal->group_exit_code & 0x7f;
1723 break;
1724 case CLD_TRAPPED:
1725 info.si_status = tsk->exit_code & 0x7f;
1726 break;
1727 default:
1728 BUG();
1729 }
1730
1731 sighand = parent->sighand;
1732 spin_lock_irqsave(&sighand->siglock, flags);
1733 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1734 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1735 __group_send_sig_info(SIGCHLD, &info, parent);
1736 /*
1737 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1738 */
1739 __wake_up_parent(tsk, parent);
1740 spin_unlock_irqrestore(&sighand->siglock, flags);
1741 }
1742
1743 static inline int may_ptrace_stop(void)
1744 {
1745 if (!likely(current->ptrace))
1746 return 0;
1747 /*
1748 * Are we in the middle of do_coredump?
1749 * If so and our tracer is also part of the coredump stopping
1750 * is a deadlock situation, and pointless because our tracer
1751 * is dead so don't allow us to stop.
1752 * If SIGKILL was already sent before the caller unlocked
1753 * ->siglock we must see ->core_state != NULL. Otherwise it
1754 * is safe to enter schedule().
1755 *
1756 * This is almost outdated, a task with the pending SIGKILL can't
1757 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1758 * after SIGKILL was already dequeued.
1759 */
1760 if (unlikely(current->mm->core_state) &&
1761 unlikely(current->mm == current->parent->mm))
1762 return 0;
1763
1764 return 1;
1765 }
1766
1767 /*
1768 * Return non-zero if there is a SIGKILL that should be waking us up.
1769 * Called with the siglock held.
1770 */
1771 static int sigkill_pending(struct task_struct *tsk)
1772 {
1773 return sigismember(&tsk->pending.signal, SIGKILL) ||
1774 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1775 }
1776
1777 /*
1778 * This must be called with current->sighand->siglock held.
1779 *
1780 * This should be the path for all ptrace stops.
1781 * We always set current->last_siginfo while stopped here.
1782 * That makes it a way to test a stopped process for
1783 * being ptrace-stopped vs being job-control-stopped.
1784 *
1785 * If we actually decide not to stop at all because the tracer
1786 * is gone, we keep current->exit_code unless clear_code.
1787 */
1788 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1789 __releases(&current->sighand->siglock)
1790 __acquires(&current->sighand->siglock)
1791 {
1792 bool gstop_done = false;
1793
1794 if (arch_ptrace_stop_needed(exit_code, info)) {
1795 /*
1796 * The arch code has something special to do before a
1797 * ptrace stop. This is allowed to block, e.g. for faults
1798 * on user stack pages. We can't keep the siglock while
1799 * calling arch_ptrace_stop, so we must release it now.
1800 * To preserve proper semantics, we must do this before
1801 * any signal bookkeeping like checking group_stop_count.
1802 * Meanwhile, a SIGKILL could come in before we retake the
1803 * siglock. That must prevent us from sleeping in TASK_TRACED.
1804 * So after regaining the lock, we must check for SIGKILL.
1805 */
1806 spin_unlock_irq(&current->sighand->siglock);
1807 arch_ptrace_stop(exit_code, info);
1808 spin_lock_irq(&current->sighand->siglock);
1809 if (sigkill_pending(current))
1810 return;
1811 }
1812
1813 /*
1814 * We're committing to trapping. TRACED should be visible before
1815 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1816 * Also, transition to TRACED and updates to ->jobctl should be
1817 * atomic with respect to siglock and should be done after the arch
1818 * hook as siglock is released and regrabbed across it.
1819 */
1820 set_current_state(TASK_TRACED);
1821
1822 current->last_siginfo = info;
1823 current->exit_code = exit_code;
1824
1825 /*
1826 * If @why is CLD_STOPPED, we're trapping to participate in a group
1827 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1828 * across siglock relocks since INTERRUPT was scheduled, PENDING
1829 * could be clear now. We act as if SIGCONT is received after
1830 * TASK_TRACED is entered - ignore it.
1831 */
1832 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1833 gstop_done = task_participate_group_stop(current);
1834
1835 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1836 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1837 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1838 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1839
1840 /* entering a trap, clear TRAPPING */
1841 task_clear_jobctl_trapping(current);
1842
1843 spin_unlock_irq(&current->sighand->siglock);
1844 read_lock(&tasklist_lock);
1845 if (may_ptrace_stop()) {
1846 /*
1847 * Notify parents of the stop.
1848 *
1849 * While ptraced, there are two parents - the ptracer and
1850 * the real_parent of the group_leader. The ptracer should
1851 * know about every stop while the real parent is only
1852 * interested in the completion of group stop. The states
1853 * for the two don't interact with each other. Notify
1854 * separately unless they're gonna be duplicates.
1855 */
1856 do_notify_parent_cldstop(current, true, why);
1857 if (gstop_done && ptrace_reparented(current))
1858 do_notify_parent_cldstop(current, false, why);
1859
1860 /*
1861 * Don't want to allow preemption here, because
1862 * sys_ptrace() needs this task to be inactive.
1863 *
1864 * XXX: implement read_unlock_no_resched().
1865 */
1866 preempt_disable();
1867 read_unlock(&tasklist_lock);
1868 preempt_enable_no_resched();
1869 freezable_schedule();
1870 } else {
1871 /*
1872 * By the time we got the lock, our tracer went away.
1873 * Don't drop the lock yet, another tracer may come.
1874 *
1875 * If @gstop_done, the ptracer went away between group stop
1876 * completion and here. During detach, it would have set
1877 * JOBCTL_STOP_PENDING on us and we'll re-enter
1878 * TASK_STOPPED in do_signal_stop() on return, so notifying
1879 * the real parent of the group stop completion is enough.
1880 */
1881 if (gstop_done)
1882 do_notify_parent_cldstop(current, false, why);
1883
1884 /* tasklist protects us from ptrace_freeze_traced() */
1885 __set_current_state(TASK_RUNNING);
1886 if (clear_code)
1887 current->exit_code = 0;
1888 read_unlock(&tasklist_lock);
1889 }
1890
1891 /*
1892 * We are back. Now reacquire the siglock before touching
1893 * last_siginfo, so that we are sure to have synchronized with
1894 * any signal-sending on another CPU that wants to examine it.
1895 */
1896 spin_lock_irq(&current->sighand->siglock);
1897 current->last_siginfo = NULL;
1898
1899 /* LISTENING can be set only during STOP traps, clear it */
1900 current->jobctl &= ~JOBCTL_LISTENING;
1901
1902 /*
1903 * Queued signals ignored us while we were stopped for tracing.
1904 * So check for any that we should take before resuming user mode.
1905 * This sets TIF_SIGPENDING, but never clears it.
1906 */
1907 recalc_sigpending_tsk(current);
1908 }
1909
1910 static void ptrace_do_notify(int signr, int exit_code, int why)
1911 {
1912 siginfo_t info;
1913
1914 memset(&info, 0, sizeof info);
1915 info.si_signo = signr;
1916 info.si_code = exit_code;
1917 info.si_pid = task_pid_vnr(current);
1918 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1919
1920 /* Let the debugger run. */
1921 ptrace_stop(exit_code, why, 1, &info);
1922 }
1923
1924 void ptrace_notify(int exit_code)
1925 {
1926 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1927 if (unlikely(current->task_works))
1928 task_work_run();
1929
1930 spin_lock_irq(&current->sighand->siglock);
1931 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1932 spin_unlock_irq(&current->sighand->siglock);
1933 }
1934
1935 /**
1936 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1937 * @signr: signr causing group stop if initiating
1938 *
1939 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1940 * and participate in it. If already set, participate in the existing
1941 * group stop. If participated in a group stop (and thus slept), %true is
1942 * returned with siglock released.
1943 *
1944 * If ptraced, this function doesn't handle stop itself. Instead,
1945 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1946 * untouched. The caller must ensure that INTERRUPT trap handling takes
1947 * places afterwards.
1948 *
1949 * CONTEXT:
1950 * Must be called with @current->sighand->siglock held, which is released
1951 * on %true return.
1952 *
1953 * RETURNS:
1954 * %false if group stop is already cancelled or ptrace trap is scheduled.
1955 * %true if participated in group stop.
1956 */
1957 static bool do_signal_stop(int signr)
1958 __releases(&current->sighand->siglock)
1959 {
1960 struct signal_struct *sig = current->signal;
1961
1962 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1963 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1964 struct task_struct *t;
1965
1966 /* signr will be recorded in task->jobctl for retries */
1967 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1968
1969 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1970 unlikely(signal_group_exit(sig)))
1971 return false;
1972 /*
1973 * There is no group stop already in progress. We must
1974 * initiate one now.
1975 *
1976 * While ptraced, a task may be resumed while group stop is
1977 * still in effect and then receive a stop signal and
1978 * initiate another group stop. This deviates from the
1979 * usual behavior as two consecutive stop signals can't
1980 * cause two group stops when !ptraced. That is why we
1981 * also check !task_is_stopped(t) below.
1982 *
1983 * The condition can be distinguished by testing whether
1984 * SIGNAL_STOP_STOPPED is already set. Don't generate
1985 * group_exit_code in such case.
1986 *
1987 * This is not necessary for SIGNAL_STOP_CONTINUED because
1988 * an intervening stop signal is required to cause two
1989 * continued events regardless of ptrace.
1990 */
1991 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1992 sig->group_exit_code = signr;
1993
1994 sig->group_stop_count = 0;
1995
1996 if (task_set_jobctl_pending(current, signr | gstop))
1997 sig->group_stop_count++;
1998
1999 t = current;
2000 while_each_thread(current, t) {
2001 /*
2002 * Setting state to TASK_STOPPED for a group
2003 * stop is always done with the siglock held,
2004 * so this check has no races.
2005 */
2006 if (!task_is_stopped(t) &&
2007 task_set_jobctl_pending(t, signr | gstop)) {
2008 sig->group_stop_count++;
2009 if (likely(!(t->ptrace & PT_SEIZED)))
2010 signal_wake_up(t, 0);
2011 else
2012 ptrace_trap_notify(t);
2013 }
2014 }
2015 }
2016
2017 if (likely(!current->ptrace)) {
2018 int notify = 0;
2019
2020 /*
2021 * If there are no other threads in the group, or if there
2022 * is a group stop in progress and we are the last to stop,
2023 * report to the parent.
2024 */
2025 if (task_participate_group_stop(current))
2026 notify = CLD_STOPPED;
2027
2028 __set_current_state(TASK_STOPPED);
2029 spin_unlock_irq(&current->sighand->siglock);
2030
2031 /*
2032 * Notify the parent of the group stop completion. Because
2033 * we're not holding either the siglock or tasklist_lock
2034 * here, ptracer may attach inbetween; however, this is for
2035 * group stop and should always be delivered to the real
2036 * parent of the group leader. The new ptracer will get
2037 * its notification when this task transitions into
2038 * TASK_TRACED.
2039 */
2040 if (notify) {
2041 read_lock(&tasklist_lock);
2042 do_notify_parent_cldstop(current, false, notify);
2043 read_unlock(&tasklist_lock);
2044 }
2045
2046 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2047 freezable_schedule();
2048 return true;
2049 } else {
2050 /*
2051 * While ptraced, group stop is handled by STOP trap.
2052 * Schedule it and let the caller deal with it.
2053 */
2054 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2055 return false;
2056 }
2057 }
2058
2059 /**
2060 * do_jobctl_trap - take care of ptrace jobctl traps
2061 *
2062 * When PT_SEIZED, it's used for both group stop and explicit
2063 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2064 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2065 * the stop signal; otherwise, %SIGTRAP.
2066 *
2067 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2068 * number as exit_code and no siginfo.
2069 *
2070 * CONTEXT:
2071 * Must be called with @current->sighand->siglock held, which may be
2072 * released and re-acquired before returning with intervening sleep.
2073 */
2074 static void do_jobctl_trap(void)
2075 {
2076 struct signal_struct *signal = current->signal;
2077 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2078
2079 if (current->ptrace & PT_SEIZED) {
2080 if (!signal->group_stop_count &&
2081 !(signal->flags & SIGNAL_STOP_STOPPED))
2082 signr = SIGTRAP;
2083 WARN_ON_ONCE(!signr);
2084 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2085 CLD_STOPPED);
2086 } else {
2087 WARN_ON_ONCE(!signr);
2088 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2089 current->exit_code = 0;
2090 }
2091 }
2092
2093 static int ptrace_signal(int signr, siginfo_t *info)
2094 {
2095 ptrace_signal_deliver();
2096 /*
2097 * We do not check sig_kernel_stop(signr) but set this marker
2098 * unconditionally because we do not know whether debugger will
2099 * change signr. This flag has no meaning unless we are going
2100 * to stop after return from ptrace_stop(). In this case it will
2101 * be checked in do_signal_stop(), we should only stop if it was
2102 * not cleared by SIGCONT while we were sleeping. See also the
2103 * comment in dequeue_signal().
2104 */
2105 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2106 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2107
2108 /* We're back. Did the debugger cancel the sig? */
2109 signr = current->exit_code;
2110 if (signr == 0)
2111 return signr;
2112
2113 current->exit_code = 0;
2114
2115 /*
2116 * Update the siginfo structure if the signal has
2117 * changed. If the debugger wanted something
2118 * specific in the siginfo structure then it should
2119 * have updated *info via PTRACE_SETSIGINFO.
2120 */
2121 if (signr != info->si_signo) {
2122 info->si_signo = signr;
2123 info->si_errno = 0;
2124 info->si_code = SI_USER;
2125 rcu_read_lock();
2126 info->si_pid = task_pid_vnr(current->parent);
2127 info->si_uid = from_kuid_munged(current_user_ns(),
2128 task_uid(current->parent));
2129 rcu_read_unlock();
2130 }
2131
2132 /* If the (new) signal is now blocked, requeue it. */
2133 if (sigismember(&current->blocked, signr)) {
2134 specific_send_sig_info(signr, info, current);
2135 signr = 0;
2136 }
2137
2138 return signr;
2139 }
2140
2141 int get_signal(struct ksignal *ksig)
2142 {
2143 struct sighand_struct *sighand = current->sighand;
2144 struct signal_struct *signal = current->signal;
2145 int signr;
2146
2147 if (unlikely(current->task_works))
2148 task_work_run();
2149
2150 if (unlikely(uprobe_deny_signal()))
2151 return 0;
2152
2153 /*
2154 * Do this once, we can't return to user-mode if freezing() == T.
2155 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2156 * thus do not need another check after return.
2157 */
2158 try_to_freeze();
2159
2160 relock:
2161 spin_lock_irq(&sighand->siglock);
2162 /*
2163 * Every stopped thread goes here after wakeup. Check to see if
2164 * we should notify the parent, prepare_signal(SIGCONT) encodes
2165 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2166 */
2167 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2168 int why;
2169
2170 if (signal->flags & SIGNAL_CLD_CONTINUED)
2171 why = CLD_CONTINUED;
2172 else
2173 why = CLD_STOPPED;
2174
2175 signal->flags &= ~SIGNAL_CLD_MASK;
2176
2177 spin_unlock_irq(&sighand->siglock);
2178
2179 /*
2180 * Notify the parent that we're continuing. This event is
2181 * always per-process and doesn't make whole lot of sense
2182 * for ptracers, who shouldn't consume the state via
2183 * wait(2) either, but, for backward compatibility, notify
2184 * the ptracer of the group leader too unless it's gonna be
2185 * a duplicate.
2186 */
2187 read_lock(&tasklist_lock);
2188 do_notify_parent_cldstop(current, false, why);
2189
2190 if (ptrace_reparented(current->group_leader))
2191 do_notify_parent_cldstop(current->group_leader,
2192 true, why);
2193 read_unlock(&tasklist_lock);
2194
2195 goto relock;
2196 }
2197
2198 for (;;) {
2199 struct k_sigaction *ka;
2200
2201 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2202 do_signal_stop(0))
2203 goto relock;
2204
2205 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2206 do_jobctl_trap();
2207 spin_unlock_irq(&sighand->siglock);
2208 goto relock;
2209 }
2210
2211 signr = dequeue_signal(current, &current->blocked, &ksig->info);
2212
2213 if (!signr)
2214 break; /* will return 0 */
2215
2216 if (unlikely(current->ptrace) && signr != SIGKILL) {
2217 signr = ptrace_signal(signr, &ksig->info);
2218 if (!signr)
2219 continue;
2220 }
2221
2222 ka = &sighand->action[signr-1];
2223
2224 /* Trace actually delivered signals. */
2225 trace_signal_deliver(signr, &ksig->info, ka);
2226
2227 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2228 continue;
2229 if (ka->sa.sa_handler != SIG_DFL) {
2230 /* Run the handler. */
2231 ksig->ka = *ka;
2232
2233 if (ka->sa.sa_flags & SA_ONESHOT)
2234 ka->sa.sa_handler = SIG_DFL;
2235
2236 break; /* will return non-zero "signr" value */
2237 }
2238
2239 /*
2240 * Now we are doing the default action for this signal.
2241 */
2242 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2243 continue;
2244
2245 /*
2246 * Global init gets no signals it doesn't want.
2247 * Container-init gets no signals it doesn't want from same
2248 * container.
2249 *
2250 * Note that if global/container-init sees a sig_kernel_only()
2251 * signal here, the signal must have been generated internally
2252 * or must have come from an ancestor namespace. In either
2253 * case, the signal cannot be dropped.
2254 */
2255 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2256 !sig_kernel_only(signr))
2257 continue;
2258
2259 if (sig_kernel_stop(signr)) {
2260 /*
2261 * The default action is to stop all threads in
2262 * the thread group. The job control signals
2263 * do nothing in an orphaned pgrp, but SIGSTOP
2264 * always works. Note that siglock needs to be
2265 * dropped during the call to is_orphaned_pgrp()
2266 * because of lock ordering with tasklist_lock.
2267 * This allows an intervening SIGCONT to be posted.
2268 * We need to check for that and bail out if necessary.
2269 */
2270 if (signr != SIGSTOP) {
2271 spin_unlock_irq(&sighand->siglock);
2272
2273 /* signals can be posted during this window */
2274
2275 if (is_current_pgrp_orphaned())
2276 goto relock;
2277
2278 spin_lock_irq(&sighand->siglock);
2279 }
2280
2281 if (likely(do_signal_stop(ksig->info.si_signo))) {
2282 /* It released the siglock. */
2283 goto relock;
2284 }
2285
2286 /*
2287 * We didn't actually stop, due to a race
2288 * with SIGCONT or something like that.
2289 */
2290 continue;
2291 }
2292
2293 spin_unlock_irq(&sighand->siglock);
2294
2295 /*
2296 * Anything else is fatal, maybe with a core dump.
2297 */
2298 current->flags |= PF_SIGNALED;
2299
2300 if (sig_kernel_coredump(signr)) {
2301 if (print_fatal_signals)
2302 print_fatal_signal(ksig->info.si_signo);
2303 proc_coredump_connector(current);
2304 /*
2305 * If it was able to dump core, this kills all
2306 * other threads in the group and synchronizes with
2307 * their demise. If we lost the race with another
2308 * thread getting here, it set group_exit_code
2309 * first and our do_group_exit call below will use
2310 * that value and ignore the one we pass it.
2311 */
2312 do_coredump(&ksig->info);
2313 }
2314
2315 /*
2316 * Death signals, no core dump.
2317 */
2318 do_group_exit(ksig->info.si_signo);
2319 /* NOTREACHED */
2320 }
2321 spin_unlock_irq(&sighand->siglock);
2322
2323 ksig->sig = signr;
2324 return ksig->sig > 0;
2325 }
2326
2327 /**
2328 * signal_delivered -
2329 * @ksig: kernel signal struct
2330 * @stepping: nonzero if debugger single-step or block-step in use
2331 *
2332 * This function should be called when a signal has successfully been
2333 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2334 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2335 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2336 */
2337 static void signal_delivered(struct ksignal *ksig, int stepping)
2338 {
2339 sigset_t blocked;
2340
2341 /* A signal was successfully delivered, and the
2342 saved sigmask was stored on the signal frame,
2343 and will be restored by sigreturn. So we can
2344 simply clear the restore sigmask flag. */
2345 clear_restore_sigmask();
2346
2347 sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
2348 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2349 sigaddset(&blocked, ksig->sig);
2350 set_current_blocked(&blocked);
2351 tracehook_signal_handler(stepping);
2352 }
2353
2354 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2355 {
2356 if (failed)
2357 force_sigsegv(ksig->sig, current);
2358 else
2359 signal_delivered(ksig, stepping);
2360 }
2361
2362 /*
2363 * It could be that complete_signal() picked us to notify about the
2364 * group-wide signal. Other threads should be notified now to take
2365 * the shared signals in @which since we will not.
2366 */
2367 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2368 {
2369 sigset_t retarget;
2370 struct task_struct *t;
2371
2372 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2373 if (sigisemptyset(&retarget))
2374 return;
2375
2376 t = tsk;
2377 while_each_thread(tsk, t) {
2378 if (t->flags & PF_EXITING)
2379 continue;
2380
2381 if (!has_pending_signals(&retarget, &t->blocked))
2382 continue;
2383 /* Remove the signals this thread can handle. */
2384 sigandsets(&retarget, &retarget, &t->blocked);
2385
2386 if (!signal_pending(t))
2387 signal_wake_up(t, 0);
2388
2389 if (sigisemptyset(&retarget))
2390 break;
2391 }
2392 }
2393
2394 void exit_signals(struct task_struct *tsk)
2395 {
2396 int group_stop = 0;
2397 sigset_t unblocked;
2398
2399 /*
2400 * @tsk is about to have PF_EXITING set - lock out users which
2401 * expect stable threadgroup.
2402 */
2403 cgroup_threadgroup_change_begin(tsk);
2404
2405 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2406 tsk->flags |= PF_EXITING;
2407 cgroup_threadgroup_change_end(tsk);
2408 return;
2409 }
2410
2411 spin_lock_irq(&tsk->sighand->siglock);
2412 /*
2413 * From now this task is not visible for group-wide signals,
2414 * see wants_signal(), do_signal_stop().
2415 */
2416 tsk->flags |= PF_EXITING;
2417
2418 cgroup_threadgroup_change_end(tsk);
2419
2420 if (!signal_pending(tsk))
2421 goto out;
2422
2423 unblocked = tsk->blocked;
2424 signotset(&unblocked);
2425 retarget_shared_pending(tsk, &unblocked);
2426
2427 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2428 task_participate_group_stop(tsk))
2429 group_stop = CLD_STOPPED;
2430 out:
2431 spin_unlock_irq(&tsk->sighand->siglock);
2432
2433 /*
2434 * If group stop has completed, deliver the notification. This
2435 * should always go to the real parent of the group leader.
2436 */
2437 if (unlikely(group_stop)) {
2438 read_lock(&tasklist_lock);
2439 do_notify_parent_cldstop(tsk, false, group_stop);
2440 read_unlock(&tasklist_lock);
2441 }
2442 }
2443
2444 EXPORT_SYMBOL(recalc_sigpending);
2445 EXPORT_SYMBOL_GPL(dequeue_signal);
2446 EXPORT_SYMBOL(flush_signals);
2447 EXPORT_SYMBOL(force_sig);
2448 EXPORT_SYMBOL(send_sig);
2449 EXPORT_SYMBOL(send_sig_info);
2450 EXPORT_SYMBOL(sigprocmask);
2451
2452 /*
2453 * System call entry points.
2454 */
2455
2456 /**
2457 * sys_restart_syscall - restart a system call
2458 */
2459 SYSCALL_DEFINE0(restart_syscall)
2460 {
2461 struct restart_block *restart = &current->restart_block;
2462 return restart->fn(restart);
2463 }
2464
2465 long do_no_restart_syscall(struct restart_block *param)
2466 {
2467 return -EINTR;
2468 }
2469
2470 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2471 {
2472 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2473 sigset_t newblocked;
2474 /* A set of now blocked but previously unblocked signals. */
2475 sigandnsets(&newblocked, newset, &current->blocked);
2476 retarget_shared_pending(tsk, &newblocked);
2477 }
2478 tsk->blocked = *newset;
2479 recalc_sigpending();
2480 }
2481
2482 /**
2483 * set_current_blocked - change current->blocked mask
2484 * @newset: new mask
2485 *
2486 * It is wrong to change ->blocked directly, this helper should be used
2487 * to ensure the process can't miss a shared signal we are going to block.
2488 */
2489 void set_current_blocked(sigset_t *newset)
2490 {
2491 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2492 __set_current_blocked(newset);
2493 }
2494
2495 void __set_current_blocked(const sigset_t *newset)
2496 {
2497 struct task_struct *tsk = current;
2498
2499 /*
2500 * In case the signal mask hasn't changed, there is nothing we need
2501 * to do. The current->blocked shouldn't be modified by other task.
2502 */
2503 if (sigequalsets(&tsk->blocked, newset))
2504 return;
2505
2506 spin_lock_irq(&tsk->sighand->siglock);
2507 __set_task_blocked(tsk, newset);
2508 spin_unlock_irq(&tsk->sighand->siglock);
2509 }
2510
2511 /*
2512 * This is also useful for kernel threads that want to temporarily
2513 * (or permanently) block certain signals.
2514 *
2515 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2516 * interface happily blocks "unblockable" signals like SIGKILL
2517 * and friends.
2518 */
2519 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2520 {
2521 struct task_struct *tsk = current;
2522 sigset_t newset;
2523
2524 /* Lockless, only current can change ->blocked, never from irq */
2525 if (oldset)
2526 *oldset = tsk->blocked;
2527
2528 switch (how) {
2529 case SIG_BLOCK:
2530 sigorsets(&newset, &tsk->blocked, set);
2531 break;
2532 case SIG_UNBLOCK:
2533 sigandnsets(&newset, &tsk->blocked, set);
2534 break;
2535 case SIG_SETMASK:
2536 newset = *set;
2537 break;
2538 default:
2539 return -EINVAL;
2540 }
2541
2542 __set_current_blocked(&newset);
2543 return 0;
2544 }
2545
2546 /**
2547 * sys_rt_sigprocmask - change the list of currently blocked signals
2548 * @how: whether to add, remove, or set signals
2549 * @nset: stores pending signals
2550 * @oset: previous value of signal mask if non-null
2551 * @sigsetsize: size of sigset_t type
2552 */
2553 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2554 sigset_t __user *, oset, size_t, sigsetsize)
2555 {
2556 sigset_t old_set, new_set;
2557 int error;
2558
2559 /* XXX: Don't preclude handling different sized sigset_t's. */
2560 if (sigsetsize != sizeof(sigset_t))
2561 return -EINVAL;
2562
2563 old_set = current->blocked;
2564
2565 if (nset) {
2566 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2567 return -EFAULT;
2568 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2569
2570 error = sigprocmask(how, &new_set, NULL);
2571 if (error)
2572 return error;
2573 }
2574
2575 if (oset) {
2576 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2577 return -EFAULT;
2578 }
2579
2580 return 0;
2581 }
2582
2583 #ifdef CONFIG_COMPAT
2584 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2585 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2586 {
2587 #ifdef __BIG_ENDIAN
2588 sigset_t old_set = current->blocked;
2589
2590 /* XXX: Don't preclude handling different sized sigset_t's. */
2591 if (sigsetsize != sizeof(sigset_t))
2592 return -EINVAL;
2593
2594 if (nset) {
2595 compat_sigset_t new32;
2596 sigset_t new_set;
2597 int error;
2598 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2599 return -EFAULT;
2600
2601 sigset_from_compat(&new_set, &new32);
2602 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2603
2604 error = sigprocmask(how, &new_set, NULL);
2605 if (error)
2606 return error;
2607 }
2608 if (oset) {
2609 compat_sigset_t old32;
2610 sigset_to_compat(&old32, &old_set);
2611 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2612 return -EFAULT;
2613 }
2614 return 0;
2615 #else
2616 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2617 (sigset_t __user *)oset, sigsetsize);
2618 #endif
2619 }
2620 #endif
2621
2622 static int do_sigpending(void *set, unsigned long sigsetsize)
2623 {
2624 if (sigsetsize > sizeof(sigset_t))
2625 return -EINVAL;
2626
2627 spin_lock_irq(&current->sighand->siglock);
2628 sigorsets(set, &current->pending.signal,
2629 &current->signal->shared_pending.signal);
2630 spin_unlock_irq(&current->sighand->siglock);
2631
2632 /* Outside the lock because only this thread touches it. */
2633 sigandsets(set, &current->blocked, set);
2634 return 0;
2635 }
2636
2637 /**
2638 * sys_rt_sigpending - examine a pending signal that has been raised
2639 * while blocked
2640 * @uset: stores pending signals
2641 * @sigsetsize: size of sigset_t type or larger
2642 */
2643 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2644 {
2645 sigset_t set;
2646 int err = do_sigpending(&set, sigsetsize);
2647 if (!err && copy_to_user(uset, &set, sigsetsize))
2648 err = -EFAULT;
2649 return err;
2650 }
2651
2652 #ifdef CONFIG_COMPAT
2653 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2654 compat_size_t, sigsetsize)
2655 {
2656 #ifdef __BIG_ENDIAN
2657 sigset_t set;
2658 int err = do_sigpending(&set, sigsetsize);
2659 if (!err) {
2660 compat_sigset_t set32;
2661 sigset_to_compat(&set32, &set);
2662 /* we can get here only if sigsetsize <= sizeof(set) */
2663 if (copy_to_user(uset, &set32, sigsetsize))
2664 err = -EFAULT;
2665 }
2666 return err;
2667 #else
2668 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2669 #endif
2670 }
2671 #endif
2672
2673 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2674
2675 int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2676 {
2677 int err;
2678
2679 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2680 return -EFAULT;
2681 if (from->si_code < 0)
2682 return __copy_to_user(to, from, sizeof(siginfo_t))
2683 ? -EFAULT : 0;
2684 /*
2685 * If you change siginfo_t structure, please be sure
2686 * this code is fixed accordingly.
2687 * Please remember to update the signalfd_copyinfo() function
2688 * inside fs/signalfd.c too, in case siginfo_t changes.
2689 * It should never copy any pad contained in the structure
2690 * to avoid security leaks, but must copy the generic
2691 * 3 ints plus the relevant union member.
2692 */
2693 err = __put_user(from->si_signo, &to->si_signo);
2694 err |= __put_user(from->si_errno, &to->si_errno);
2695 err |= __put_user((short)from->si_code, &to->si_code);
2696 switch (from->si_code & __SI_MASK) {
2697 case __SI_KILL:
2698 err |= __put_user(from->si_pid, &to->si_pid);
2699 err |= __put_user(from->si_uid, &to->si_uid);
2700 break;
2701 case __SI_TIMER:
2702 err |= __put_user(from->si_tid, &to->si_tid);
2703 err |= __put_user(from->si_overrun, &to->si_overrun);
2704 err |= __put_user(from->si_ptr, &to->si_ptr);
2705 break;
2706 case __SI_POLL:
2707 err |= __put_user(from->si_band, &to->si_band);
2708 err |= __put_user(from->si_fd, &to->si_fd);
2709 break;
2710 case __SI_FAULT:
2711 err |= __put_user(from->si_addr, &to->si_addr);
2712 #ifdef __ARCH_SI_TRAPNO
2713 err |= __put_user(from->si_trapno, &to->si_trapno);
2714 #endif
2715 #ifdef BUS_MCEERR_AO
2716 /*
2717 * Other callers might not initialize the si_lsb field,
2718 * so check explicitly for the right codes here.
2719 */
2720 if (from->si_signo == SIGBUS &&
2721 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2722 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2723 #endif
2724 #ifdef SEGV_BNDERR
2725 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2726 err |= __put_user(from->si_lower, &to->si_lower);
2727 err |= __put_user(from->si_upper, &to->si_upper);
2728 }
2729 #endif
2730 #ifdef SEGV_PKUERR
2731 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2732 err |= __put_user(from->si_pkey, &to->si_pkey);
2733 #endif
2734 break;
2735 case __SI_CHLD:
2736 err |= __put_user(from->si_pid, &to->si_pid);
2737 err |= __put_user(from->si_uid, &to->si_uid);
2738 err |= __put_user(from->si_status, &to->si_status);
2739 err |= __put_user(from->si_utime, &to->si_utime);
2740 err |= __put_user(from->si_stime, &to->si_stime);
2741 break;
2742 case __SI_RT: /* This is not generated by the kernel as of now. */
2743 case __SI_MESGQ: /* But this is */
2744 err |= __put_user(from->si_pid, &to->si_pid);
2745 err |= __put_user(from->si_uid, &to->si_uid);
2746 err |= __put_user(from->si_ptr, &to->si_ptr);
2747 break;
2748 #ifdef __ARCH_SIGSYS
2749 case __SI_SYS:
2750 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2751 err |= __put_user(from->si_syscall, &to->si_syscall);
2752 err |= __put_user(from->si_arch, &to->si_arch);
2753 break;
2754 #endif
2755 default: /* this is just in case for now ... */
2756 err |= __put_user(from->si_pid, &to->si_pid);
2757 err |= __put_user(from->si_uid, &to->si_uid);
2758 break;
2759 }
2760 return err;
2761 }
2762
2763 #endif
2764
2765 /**
2766 * do_sigtimedwait - wait for queued signals specified in @which
2767 * @which: queued signals to wait for
2768 * @info: if non-null, the signal's siginfo is returned here
2769 * @ts: upper bound on process time suspension
2770 */
2771 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2772 const struct timespec *ts)
2773 {
2774 ktime_t *to = NULL, timeout = KTIME_MAX;
2775 struct task_struct *tsk = current;
2776 sigset_t mask = *which;
2777 int sig, ret = 0;
2778
2779 if (ts) {
2780 if (!timespec_valid(ts))
2781 return -EINVAL;
2782 timeout = timespec_to_ktime(*ts);
2783 to = &timeout;
2784 }
2785
2786 /*
2787 * Invert the set of allowed signals to get those we want to block.
2788 */
2789 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2790 signotset(&mask);
2791
2792 spin_lock_irq(&tsk->sighand->siglock);
2793 sig = dequeue_signal(tsk, &mask, info);
2794 if (!sig && timeout) {
2795 /*
2796 * None ready, temporarily unblock those we're interested
2797 * while we are sleeping in so that we'll be awakened when
2798 * they arrive. Unblocking is always fine, we can avoid
2799 * set_current_blocked().
2800 */
2801 tsk->real_blocked = tsk->blocked;
2802 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2803 recalc_sigpending();
2804 spin_unlock_irq(&tsk->sighand->siglock);
2805
2806 __set_current_state(TASK_INTERRUPTIBLE);
2807 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
2808 HRTIMER_MODE_REL);
2809 spin_lock_irq(&tsk->sighand->siglock);
2810 __set_task_blocked(tsk, &tsk->real_blocked);
2811 sigemptyset(&tsk->real_blocked);
2812 sig = dequeue_signal(tsk, &mask, info);
2813 }
2814 spin_unlock_irq(&tsk->sighand->siglock);
2815
2816 if (sig)
2817 return sig;
2818 return ret ? -EINTR : -EAGAIN;
2819 }
2820
2821 /**
2822 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2823 * in @uthese
2824 * @uthese: queued signals to wait for
2825 * @uinfo: if non-null, the signal's siginfo is returned here
2826 * @uts: upper bound on process time suspension
2827 * @sigsetsize: size of sigset_t type
2828 */
2829 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2830 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2831 size_t, sigsetsize)
2832 {
2833 sigset_t these;
2834 struct timespec ts;
2835 siginfo_t info;
2836 int ret;
2837
2838 /* XXX: Don't preclude handling different sized sigset_t's. */
2839 if (sigsetsize != sizeof(sigset_t))
2840 return -EINVAL;
2841
2842 if (copy_from_user(&these, uthese, sizeof(these)))
2843 return -EFAULT;
2844
2845 if (uts) {
2846 if (copy_from_user(&ts, uts, sizeof(ts)))
2847 return -EFAULT;
2848 }
2849
2850 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2851
2852 if (ret > 0 && uinfo) {
2853 if (copy_siginfo_to_user(uinfo, &info))
2854 ret = -EFAULT;
2855 }
2856
2857 return ret;
2858 }
2859
2860 /**
2861 * sys_kill - send a signal to a process
2862 * @pid: the PID of the process
2863 * @sig: signal to be sent
2864 */
2865 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2866 {
2867 struct siginfo info;
2868
2869 info.si_signo = sig;
2870 info.si_errno = 0;
2871 info.si_code = SI_USER;
2872 info.si_pid = task_tgid_vnr(current);
2873 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2874
2875 return kill_something_info(sig, &info, pid);
2876 }
2877
2878 static int
2879 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2880 {
2881 struct task_struct *p;
2882 int error = -ESRCH;
2883
2884 rcu_read_lock();
2885 p = find_task_by_vpid(pid);
2886 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2887 error = check_kill_permission(sig, info, p);
2888 /*
2889 * The null signal is a permissions and process existence
2890 * probe. No signal is actually delivered.
2891 */
2892 if (!error && sig) {
2893 error = do_send_sig_info(sig, info, p, false);
2894 /*
2895 * If lock_task_sighand() failed we pretend the task
2896 * dies after receiving the signal. The window is tiny,
2897 * and the signal is private anyway.
2898 */
2899 if (unlikely(error == -ESRCH))
2900 error = 0;
2901 }
2902 }
2903 rcu_read_unlock();
2904
2905 return error;
2906 }
2907
2908 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2909 {
2910 struct siginfo info = {};
2911
2912 info.si_signo = sig;
2913 info.si_errno = 0;
2914 info.si_code = SI_TKILL;
2915 info.si_pid = task_tgid_vnr(current);
2916 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2917
2918 return do_send_specific(tgid, pid, sig, &info);
2919 }
2920
2921 /**
2922 * sys_tgkill - send signal to one specific thread
2923 * @tgid: the thread group ID of the thread
2924 * @pid: the PID of the thread
2925 * @sig: signal to be sent
2926 *
2927 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2928 * exists but it's not belonging to the target process anymore. This
2929 * method solves the problem of threads exiting and PIDs getting reused.
2930 */
2931 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2932 {
2933 /* This is only valid for single tasks */
2934 if (pid <= 0 || tgid <= 0)
2935 return -EINVAL;
2936
2937 return do_tkill(tgid, pid, sig);
2938 }
2939
2940 /**
2941 * sys_tkill - send signal to one specific task
2942 * @pid: the PID of the task
2943 * @sig: signal to be sent
2944 *
2945 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2946 */
2947 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2948 {
2949 /* This is only valid for single tasks */
2950 if (pid <= 0)
2951 return -EINVAL;
2952
2953 return do_tkill(0, pid, sig);
2954 }
2955
2956 static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2957 {
2958 /* Not even root can pretend to send signals from the kernel.
2959 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2960 */
2961 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2962 (task_pid_vnr(current) != pid))
2963 return -EPERM;
2964
2965 info->si_signo = sig;
2966
2967 /* POSIX.1b doesn't mention process groups. */
2968 return kill_proc_info(sig, info, pid);
2969 }
2970
2971 /**
2972 * sys_rt_sigqueueinfo - send signal information to a signal
2973 * @pid: the PID of the thread
2974 * @sig: signal to be sent
2975 * @uinfo: signal info to be sent
2976 */
2977 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2978 siginfo_t __user *, uinfo)
2979 {
2980 siginfo_t info;
2981 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2982 return -EFAULT;
2983 return do_rt_sigqueueinfo(pid, sig, &info);
2984 }
2985
2986 #ifdef CONFIG_COMPAT
2987 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
2988 compat_pid_t, pid,
2989 int, sig,
2990 struct compat_siginfo __user *, uinfo)
2991 {
2992 siginfo_t info = {};
2993 int ret = copy_siginfo_from_user32(&info, uinfo);
2994 if (unlikely(ret))
2995 return ret;
2996 return do_rt_sigqueueinfo(pid, sig, &info);
2997 }
2998 #endif
2999
3000 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3001 {
3002 /* This is only valid for single tasks */
3003 if (pid <= 0 || tgid <= 0)
3004 return -EINVAL;
3005
3006 /* Not even root can pretend to send signals from the kernel.
3007 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3008 */
3009 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3010 (task_pid_vnr(current) != pid))
3011 return -EPERM;
3012
3013 info->si_signo = sig;
3014
3015 return do_send_specific(tgid, pid, sig, info);
3016 }
3017
3018 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3019 siginfo_t __user *, uinfo)
3020 {
3021 siginfo_t info;
3022
3023 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3024 return -EFAULT;
3025
3026 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3027 }
3028
3029 #ifdef CONFIG_COMPAT
3030 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3031 compat_pid_t, tgid,
3032 compat_pid_t, pid,
3033 int, sig,
3034 struct compat_siginfo __user *, uinfo)
3035 {
3036 siginfo_t info = {};
3037
3038 if (copy_siginfo_from_user32(&info, uinfo))
3039 return -EFAULT;
3040 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3041 }
3042 #endif
3043
3044 /*
3045 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3046 */
3047 void kernel_sigaction(int sig, __sighandler_t action)
3048 {
3049 spin_lock_irq(&current->sighand->siglock);
3050 current->sighand->action[sig - 1].sa.sa_handler = action;
3051 if (action == SIG_IGN) {
3052 sigset_t mask;
3053
3054 sigemptyset(&mask);
3055 sigaddset(&mask, sig);
3056
3057 flush_sigqueue_mask(&mask, &current->signal->shared_pending);
3058 flush_sigqueue_mask(&mask, &current->pending);
3059 recalc_sigpending();
3060 }
3061 spin_unlock_irq(&current->sighand->siglock);
3062 }
3063 EXPORT_SYMBOL(kernel_sigaction);
3064
3065 void __weak sigaction_compat_abi(struct k_sigaction *act,
3066 struct k_sigaction *oact)
3067 {
3068 }
3069
3070 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3071 {
3072 struct task_struct *p = current, *t;
3073 struct k_sigaction *k;
3074 sigset_t mask;
3075
3076 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3077 return -EINVAL;
3078
3079 k = &p->sighand->action[sig-1];
3080
3081 spin_lock_irq(&p->sighand->siglock);
3082 if (oact)
3083 *oact = *k;
3084
3085 sigaction_compat_abi(act, oact);
3086
3087 if (act) {
3088 sigdelsetmask(&act->sa.sa_mask,
3089 sigmask(SIGKILL) | sigmask(SIGSTOP));
3090 *k = *act;
3091 /*
3092 * POSIX 3.3.1.3:
3093 * "Setting a signal action to SIG_IGN for a signal that is
3094 * pending shall cause the pending signal to be discarded,
3095 * whether or not it is blocked."
3096 *
3097 * "Setting a signal action to SIG_DFL for a signal that is
3098 * pending and whose default action is to ignore the signal
3099 * (for example, SIGCHLD), shall cause the pending signal to
3100 * be discarded, whether or not it is blocked"
3101 */
3102 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3103 sigemptyset(&mask);
3104 sigaddset(&mask, sig);
3105 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3106 for_each_thread(p, t)
3107 flush_sigqueue_mask(&mask, &t->pending);
3108 }
3109 }
3110
3111 spin_unlock_irq(&p->sighand->siglock);
3112 return 0;
3113 }
3114
3115 static int
3116 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3117 {
3118 stack_t oss;
3119 int error;
3120
3121 oss.ss_sp = (void __user *) current->sas_ss_sp;
3122 oss.ss_size = current->sas_ss_size;
3123 oss.ss_flags = sas_ss_flags(sp) |
3124 (current->sas_ss_flags & SS_FLAG_BITS);
3125
3126 if (uss) {
3127 void __user *ss_sp;
3128 size_t ss_size;
3129 unsigned ss_flags;
3130 int ss_mode;
3131
3132 error = -EFAULT;
3133 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3134 goto out;
3135 error = __get_user(ss_sp, &uss->ss_sp) |
3136 __get_user(ss_flags, &uss->ss_flags) |
3137 __get_user(ss_size, &uss->ss_size);
3138 if (error)
3139 goto out;
3140
3141 error = -EPERM;
3142 if (on_sig_stack(sp))
3143 goto out;
3144
3145 ss_mode = ss_flags & ~SS_FLAG_BITS;
3146 error = -EINVAL;
3147 if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3148 ss_mode != 0)
3149 goto out;
3150
3151 if (ss_mode == SS_DISABLE) {
3152 ss_size = 0;
3153 ss_sp = NULL;
3154 } else {
3155 error = -ENOMEM;
3156 if (ss_size < MINSIGSTKSZ)
3157 goto out;
3158 }
3159
3160 current->sas_ss_sp = (unsigned long) ss_sp;
3161 current->sas_ss_size = ss_size;
3162 current->sas_ss_flags = ss_flags;
3163 }
3164
3165 error = 0;
3166 if (uoss) {
3167 error = -EFAULT;
3168 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3169 goto out;
3170 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3171 __put_user(oss.ss_size, &uoss->ss_size) |
3172 __put_user(oss.ss_flags, &uoss->ss_flags);
3173 }
3174
3175 out:
3176 return error;
3177 }
3178 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3179 {
3180 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3181 }
3182
3183 int restore_altstack(const stack_t __user *uss)
3184 {
3185 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3186 /* squash all but EFAULT for now */
3187 return err == -EFAULT ? err : 0;
3188 }
3189
3190 int __save_altstack(stack_t __user *uss, unsigned long sp)
3191 {
3192 struct task_struct *t = current;
3193 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3194 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3195 __put_user(t->sas_ss_size, &uss->ss_size);
3196 if (err)
3197 return err;
3198 if (t->sas_ss_flags & SS_AUTODISARM)
3199 sas_ss_reset(t);
3200 return 0;
3201 }
3202
3203 #ifdef CONFIG_COMPAT
3204 COMPAT_SYSCALL_DEFINE2(sigaltstack,
3205 const compat_stack_t __user *, uss_ptr,
3206 compat_stack_t __user *, uoss_ptr)
3207 {
3208 stack_t uss, uoss;
3209 int ret;
3210 mm_segment_t seg;
3211
3212 if (uss_ptr) {
3213 compat_stack_t uss32;
3214
3215 memset(&uss, 0, sizeof(stack_t));
3216 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3217 return -EFAULT;
3218 uss.ss_sp = compat_ptr(uss32.ss_sp);
3219 uss.ss_flags = uss32.ss_flags;
3220 uss.ss_size = uss32.ss_size;
3221 }
3222 seg = get_fs();
3223 set_fs(KERNEL_DS);
3224 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3225 (stack_t __force __user *) &uoss,
3226 compat_user_stack_pointer());
3227 set_fs(seg);
3228 if (ret >= 0 && uoss_ptr) {
3229 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3230 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3231 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3232 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3233 ret = -EFAULT;
3234 }
3235 return ret;
3236 }
3237
3238 int compat_restore_altstack(const compat_stack_t __user *uss)
3239 {
3240 int err = compat_sys_sigaltstack(uss, NULL);
3241 /* squash all but -EFAULT for now */
3242 return err == -EFAULT ? err : 0;
3243 }
3244
3245 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3246 {
3247 int err;
3248 struct task_struct *t = current;
3249 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3250 &uss->ss_sp) |
3251 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3252 __put_user(t->sas_ss_size, &uss->ss_size);
3253 if (err)
3254 return err;
3255 if (t->sas_ss_flags & SS_AUTODISARM)
3256 sas_ss_reset(t);
3257 return 0;
3258 }
3259 #endif
3260
3261 #ifdef __ARCH_WANT_SYS_SIGPENDING
3262
3263 /**
3264 * sys_sigpending - examine pending signals
3265 * @set: where mask of pending signal is returned
3266 */
3267 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3268 {
3269 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3270 }
3271
3272 #endif
3273
3274 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3275 /**
3276 * sys_sigprocmask - examine and change blocked signals
3277 * @how: whether to add, remove, or set signals
3278 * @nset: signals to add or remove (if non-null)
3279 * @oset: previous value of signal mask if non-null
3280 *
3281 * Some platforms have their own version with special arguments;
3282 * others support only sys_rt_sigprocmask.
3283 */
3284
3285 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3286 old_sigset_t __user *, oset)
3287 {
3288 old_sigset_t old_set, new_set;
3289 sigset_t new_blocked;
3290
3291 old_set = current->blocked.sig[0];
3292
3293 if (nset) {
3294 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3295 return -EFAULT;
3296
3297 new_blocked = current->blocked;
3298
3299 switch (how) {
3300 case SIG_BLOCK:
3301 sigaddsetmask(&new_blocked, new_set);
3302 break;
3303 case SIG_UNBLOCK:
3304 sigdelsetmask(&new_blocked, new_set);
3305 break;
3306 case SIG_SETMASK:
3307 new_blocked.sig[0] = new_set;
3308 break;
3309 default:
3310 return -EINVAL;
3311 }
3312
3313 set_current_blocked(&new_blocked);
3314 }
3315
3316 if (oset) {
3317 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3318 return -EFAULT;
3319 }
3320
3321 return 0;
3322 }
3323 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3324
3325 #ifndef CONFIG_ODD_RT_SIGACTION
3326 /**
3327 * sys_rt_sigaction - alter an action taken by a process
3328 * @sig: signal to be sent
3329 * @act: new sigaction
3330 * @oact: used to save the previous sigaction
3331 * @sigsetsize: size of sigset_t type
3332 */
3333 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3334 const struct sigaction __user *, act,
3335 struct sigaction __user *, oact,
3336 size_t, sigsetsize)
3337 {
3338 struct k_sigaction new_sa, old_sa;
3339 int ret = -EINVAL;
3340
3341 /* XXX: Don't preclude handling different sized sigset_t's. */
3342 if (sigsetsize != sizeof(sigset_t))
3343 goto out;
3344
3345 if (act) {
3346 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3347 return -EFAULT;
3348 }
3349
3350 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3351
3352 if (!ret && oact) {
3353 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3354 return -EFAULT;
3355 }
3356 out:
3357 return ret;
3358 }
3359 #ifdef CONFIG_COMPAT
3360 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3361 const struct compat_sigaction __user *, act,
3362 struct compat_sigaction __user *, oact,
3363 compat_size_t, sigsetsize)
3364 {
3365 struct k_sigaction new_ka, old_ka;
3366 compat_sigset_t mask;
3367 #ifdef __ARCH_HAS_SA_RESTORER
3368 compat_uptr_t restorer;
3369 #endif
3370 int ret;
3371
3372 /* XXX: Don't preclude handling different sized sigset_t's. */
3373 if (sigsetsize != sizeof(compat_sigset_t))
3374 return -EINVAL;
3375
3376 if (act) {
3377 compat_uptr_t handler;
3378 ret = get_user(handler, &act->sa_handler);
3379 new_ka.sa.sa_handler = compat_ptr(handler);
3380 #ifdef __ARCH_HAS_SA_RESTORER
3381 ret |= get_user(restorer, &act->sa_restorer);
3382 new_ka.sa.sa_restorer = compat_ptr(restorer);
3383 #endif
3384 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3385 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3386 if (ret)
3387 return -EFAULT;
3388 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3389 }
3390
3391 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3392 if (!ret && oact) {
3393 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3394 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3395 &oact->sa_handler);
3396 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3397 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3398 #ifdef __ARCH_HAS_SA_RESTORER
3399 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3400 &oact->sa_restorer);
3401 #endif
3402 }
3403 return ret;
3404 }
3405 #endif
3406 #endif /* !CONFIG_ODD_RT_SIGACTION */
3407
3408 #ifdef CONFIG_OLD_SIGACTION
3409 SYSCALL_DEFINE3(sigaction, int, sig,
3410 const struct old_sigaction __user *, act,
3411 struct old_sigaction __user *, oact)
3412 {
3413 struct k_sigaction new_ka, old_ka;
3414 int ret;
3415
3416 if (act) {
3417 old_sigset_t mask;
3418 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3419 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3420 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3421 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3422 __get_user(mask, &act->sa_mask))
3423 return -EFAULT;
3424 #ifdef __ARCH_HAS_KA_RESTORER
3425 new_ka.ka_restorer = NULL;
3426 #endif
3427 siginitset(&new_ka.sa.sa_mask, mask);
3428 }
3429
3430 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3431
3432 if (!ret && oact) {
3433 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3434 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3435 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3436 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3437 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3438 return -EFAULT;
3439 }
3440
3441 return ret;
3442 }
3443 #endif
3444 #ifdef CONFIG_COMPAT_OLD_SIGACTION
3445 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3446 const struct compat_old_sigaction __user *, act,
3447 struct compat_old_sigaction __user *, oact)
3448 {
3449 struct k_sigaction new_ka, old_ka;
3450 int ret;
3451 compat_old_sigset_t mask;
3452 compat_uptr_t handler, restorer;
3453
3454 if (act) {
3455 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3456 __get_user(handler, &act->sa_handler) ||
3457 __get_user(restorer, &act->sa_restorer) ||
3458 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3459 __get_user(mask, &act->sa_mask))
3460 return -EFAULT;
3461
3462 #ifdef __ARCH_HAS_KA_RESTORER
3463 new_ka.ka_restorer = NULL;
3464 #endif
3465 new_ka.sa.sa_handler = compat_ptr(handler);
3466 new_ka.sa.sa_restorer = compat_ptr(restorer);
3467 siginitset(&new_ka.sa.sa_mask, mask);
3468 }
3469
3470 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3471
3472 if (!ret && oact) {
3473 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3474 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3475 &oact->sa_handler) ||
3476 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3477 &oact->sa_restorer) ||
3478 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3479 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3480 return -EFAULT;
3481 }
3482 return ret;
3483 }
3484 #endif
3485
3486 #ifdef CONFIG_SGETMASK_SYSCALL
3487
3488 /*
3489 * For backwards compatibility. Functionality superseded by sigprocmask.
3490 */
3491 SYSCALL_DEFINE0(sgetmask)
3492 {
3493 /* SMP safe */
3494 return current->blocked.sig[0];
3495 }
3496
3497 SYSCALL_DEFINE1(ssetmask, int, newmask)
3498 {
3499 int old = current->blocked.sig[0];
3500 sigset_t newset;
3501
3502 siginitset(&newset, newmask);
3503 set_current_blocked(&newset);
3504
3505 return old;
3506 }
3507 #endif /* CONFIG_SGETMASK_SYSCALL */
3508
3509 #ifdef __ARCH_WANT_SYS_SIGNAL
3510 /*
3511 * For backwards compatibility. Functionality superseded by sigaction.
3512 */
3513 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3514 {
3515 struct k_sigaction new_sa, old_sa;
3516 int ret;
3517
3518 new_sa.sa.sa_handler = handler;
3519 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3520 sigemptyset(&new_sa.sa.sa_mask);
3521
3522 ret = do_sigaction(sig, &new_sa, &old_sa);
3523
3524 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3525 }
3526 #endif /* __ARCH_WANT_SYS_SIGNAL */
3527
3528 #ifdef __ARCH_WANT_SYS_PAUSE
3529
3530 SYSCALL_DEFINE0(pause)
3531 {
3532 while (!signal_pending(current)) {
3533 __set_current_state(TASK_INTERRUPTIBLE);
3534 schedule();
3535 }
3536 return -ERESTARTNOHAND;
3537 }
3538
3539 #endif
3540
3541 static int sigsuspend(sigset_t *set)
3542 {
3543 current->saved_sigmask = current->blocked;
3544 set_current_blocked(set);
3545
3546 while (!signal_pending(current)) {
3547 __set_current_state(TASK_INTERRUPTIBLE);
3548 schedule();
3549 }
3550 set_restore_sigmask();
3551 return -ERESTARTNOHAND;
3552 }
3553
3554 /**
3555 * sys_rt_sigsuspend - replace the signal mask for a value with the
3556 * @unewset value until a signal is received
3557 * @unewset: new signal mask value
3558 * @sigsetsize: size of sigset_t type
3559 */
3560 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3561 {
3562 sigset_t newset;
3563
3564 /* XXX: Don't preclude handling different sized sigset_t's. */
3565 if (sigsetsize != sizeof(sigset_t))
3566 return -EINVAL;
3567
3568 if (copy_from_user(&newset, unewset, sizeof(newset)))
3569 return -EFAULT;
3570 return sigsuspend(&newset);
3571 }
3572
3573 #ifdef CONFIG_COMPAT
3574 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3575 {
3576 #ifdef __BIG_ENDIAN
3577 sigset_t newset;
3578 compat_sigset_t newset32;
3579
3580 /* XXX: Don't preclude handling different sized sigset_t's. */
3581 if (sigsetsize != sizeof(sigset_t))
3582 return -EINVAL;
3583
3584 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3585 return -EFAULT;
3586 sigset_from_compat(&newset, &newset32);
3587 return sigsuspend(&newset);
3588 #else
3589 /* on little-endian bitmaps don't care about granularity */
3590 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3591 #endif
3592 }
3593 #endif
3594
3595 #ifdef CONFIG_OLD_SIGSUSPEND
3596 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3597 {
3598 sigset_t blocked;
3599 siginitset(&blocked, mask);
3600 return sigsuspend(&blocked);
3601 }
3602 #endif
3603 #ifdef CONFIG_OLD_SIGSUSPEND3
3604 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3605 {
3606 sigset_t blocked;
3607 siginitset(&blocked, mask);
3608 return sigsuspend(&blocked);
3609 }
3610 #endif
3611
3612 __weak const char *arch_vma_name(struct vm_area_struct *vma)
3613 {
3614 return NULL;
3615 }
3616
3617 void __init signals_init(void)
3618 {
3619 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3620 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3621 != offsetof(struct siginfo, _sifields._pad));
3622
3623 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3624 }
3625
3626 #ifdef CONFIG_KGDB_KDB
3627 #include <linux/kdb.h>
3628 /*
3629 * kdb_send_sig_info - Allows kdb to send signals without exposing
3630 * signal internals. This function checks if the required locks are
3631 * available before calling the main signal code, to avoid kdb
3632 * deadlocks.
3633 */
3634 void
3635 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3636 {
3637 static struct task_struct *kdb_prev_t;
3638 int sig, new_t;
3639 if (!spin_trylock(&t->sighand->siglock)) {
3640 kdb_printf("Can't do kill command now.\n"
3641 "The sigmask lock is held somewhere else in "
3642 "kernel, try again later\n");
3643 return;
3644 }
3645 spin_unlock(&t->sighand->siglock);
3646 new_t = kdb_prev_t != t;
3647 kdb_prev_t = t;
3648 if (t->state != TASK_RUNNING && new_t) {
3649 kdb_printf("Process is not RUNNING, sending a signal from "
3650 "kdb risks deadlock\n"
3651 "on the run queue locks. "
3652 "The signal has _not_ been sent.\n"
3653 "Reissue the kill command if you want to risk "
3654 "the deadlock.\n");
3655 return;
3656 }
3657 sig = info->si_signo;
3658 if (send_sig_info(sig, info, t))
3659 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3660 sig, t->pid);
3661 else
3662 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3663 }
3664 #endif /* CONFIG_KGDB_KDB */