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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.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/coredump.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/ptrace.h>
24#include <linux/signal.h>
25#include <linux/signalfd.h>
26#include <linux/ratelimit.h>
27#include <linux/tracehook.h>
28#include <linux/capability.h>
29#include <linux/freezer.h>
30#include <linux/pid_namespace.h>
31#include <linux/nsproxy.h>
32#include <linux/user_namespace.h>
33#include <linux/uprobes.h>
34#include <linux/compat.h>
35#include <linux/cn_proc.h>
36#include <linux/compiler.h>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <asm/uaccess.h>
43#include <asm/unistd.h>
44#include <asm/siginfo.h>
45#include <asm/cacheflush.h>
46#include "audit.h" /* audit_signal_info() */
47
48/*
49 * SLAB caches for signal bits.
50 */
51
52static struct kmem_cache *sigqueue_cachep;
53
54int print_fatal_signals __read_mostly;
55
56static void __user *sig_handler(struct task_struct *t, int sig)
57{
58 return t->sighand->action[sig - 1].sa.sa_handler;
59}
60
61static int sig_handler_ignored(void __user *handler, int sig)
62{
63 /* Is it explicitly or implicitly ignored? */
64 return handler == SIG_IGN ||
65 (handler == SIG_DFL && sig_kernel_ignore(sig));
66}
67
68static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69{
70 void __user *handler;
71
72 handler = sig_handler(t, sig);
73
74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 handler == SIG_DFL && !force)
76 return 1;
77
78 return sig_handler_ignored(handler, sig);
79}
80
81static int sig_ignored(struct task_struct *t, int sig, bool force)
82{
83 /*
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
86 * unblocked.
87 */
88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 return 0;
90
91 if (!sig_task_ignored(t, sig, force))
92 return 0;
93
94 /*
95 * Tracers may want to know about even ignored signals.
96 */
97 return !t->ptrace;
98}
99
100/*
101 * Re-calculate pending state from the set of locally pending
102 * signals, globally pending signals, and blocked signals.
103 */
104static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105{
106 unsigned long ready;
107 long i;
108
109 switch (_NSIG_WORDS) {
110 default:
111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 ready |= signal->sig[i] &~ blocked->sig[i];
113 break;
114
115 case 4: ready = signal->sig[3] &~ blocked->sig[3];
116 ready |= signal->sig[2] &~ blocked->sig[2];
117 ready |= signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
119 break;
120
121 case 2: ready = signal->sig[1] &~ blocked->sig[1];
122 ready |= signal->sig[0] &~ blocked->sig[0];
123 break;
124
125 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 }
127 return ready != 0;
128}
129
130#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131
132static int recalc_sigpending_tsk(struct task_struct *t)
133{
134 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 PENDING(&t->pending, &t->blocked) ||
136 PENDING(&t->signal->shared_pending, &t->blocked)) {
137 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 return 1;
139 }
140 /*
141 * We must never clear the flag in another thread, or in current
142 * when it's possible the current syscall is returning -ERESTART*.
143 * So we don't clear it here, and only callers who know they should do.
144 */
145 return 0;
146}
147
148/*
149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150 * This is superfluous when called on current, the wakeup is a harmless no-op.
151 */
152void recalc_sigpending_and_wake(struct task_struct *t)
153{
154 if (recalc_sigpending_tsk(t))
155 signal_wake_up(t, 0);
156}
157
158void recalc_sigpending(void)
159{
160 if (!recalc_sigpending_tsk(current) && !freezing(current))
161 clear_thread_flag(TIF_SIGPENDING);
162
163}
164
165/* Given the mask, find the first available signal that should be serviced. */
166
167#define SYNCHRONOUS_MASK \
168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170
171int next_signal(struct sigpending *pending, sigset_t *mask)
172{
173 unsigned long i, *s, *m, x;
174 int sig = 0;
175
176 s = pending->signal.sig;
177 m = mask->sig;
178
179 /*
180 * Handle the first word specially: it contains the
181 * synchronous signals that need to be dequeued first.
182 */
183 x = *s &~ *m;
184 if (x) {
185 if (x & SYNCHRONOUS_MASK)
186 x &= SYNCHRONOUS_MASK;
187 sig = ffz(~x) + 1;
188 return sig;
189 }
190
191 switch (_NSIG_WORDS) {
192 default:
193 for (i = 1; i < _NSIG_WORDS; ++i) {
194 x = *++s &~ *++m;
195 if (!x)
196 continue;
197 sig = ffz(~x) + i*_NSIG_BPW + 1;
198 break;
199 }
200 break;
201
202 case 2:
203 x = s[1] &~ m[1];
204 if (!x)
205 break;
206 sig = ffz(~x) + _NSIG_BPW + 1;
207 break;
208
209 case 1:
210 /* Nothing to do */
211 break;
212 }
213
214 return sig;
215}
216
217static inline void print_dropped_signal(int sig)
218{
219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220
221 if (!print_fatal_signals)
222 return;
223
224 if (!__ratelimit(&ratelimit_state))
225 return;
226
227 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 current->comm, current->pid, sig);
229}
230
231/**
232 * task_set_jobctl_pending - set jobctl pending bits
233 * @task: target task
234 * @mask: pending bits to set
235 *
236 * Clear @mask from @task->jobctl. @mask must be subset of
237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
239 * cleared. If @task is already being killed or exiting, this function
240 * becomes noop.
241 *
242 * CONTEXT:
243 * Must be called with @task->sighand->siglock held.
244 *
245 * RETURNS:
246 * %true if @mask is set, %false if made noop because @task was dying.
247 */
248bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
249{
250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253
254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 return false;
256
257 if (mask & JOBCTL_STOP_SIGMASK)
258 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259
260 task->jobctl |= mask;
261 return true;
262}
263
264/**
265 * task_clear_jobctl_trapping - clear jobctl trapping bit
266 * @task: target task
267 *
268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269 * Clear it and wake up the ptracer. Note that we don't need any further
270 * locking. @task->siglock guarantees that @task->parent points to the
271 * ptracer.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 */
276void task_clear_jobctl_trapping(struct task_struct *task)
277{
278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 task->jobctl &= ~JOBCTL_TRAPPING;
280 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
281 }
282}
283
284/**
285 * task_clear_jobctl_pending - clear jobctl pending bits
286 * @task: target task
287 * @mask: pending bits to clear
288 *
289 * Clear @mask from @task->jobctl. @mask must be subset of
290 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
291 * STOP bits are cleared together.
292 *
293 * If clearing of @mask leaves no stop or trap pending, this function calls
294 * task_clear_jobctl_trapping().
295 *
296 * CONTEXT:
297 * Must be called with @task->sighand->siglock held.
298 */
299void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
300{
301 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
302
303 if (mask & JOBCTL_STOP_PENDING)
304 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
305
306 task->jobctl &= ~mask;
307
308 if (!(task->jobctl & JOBCTL_PENDING_MASK))
309 task_clear_jobctl_trapping(task);
310}
311
312/**
313 * task_participate_group_stop - participate in a group stop
314 * @task: task participating in a group stop
315 *
316 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
317 * Group stop states are cleared and the group stop count is consumed if
318 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
319 * stop, the appropriate %SIGNAL_* flags are set.
320 *
321 * CONTEXT:
322 * Must be called with @task->sighand->siglock held.
323 *
324 * RETURNS:
325 * %true if group stop completion should be notified to the parent, %false
326 * otherwise.
327 */
328static bool task_participate_group_stop(struct task_struct *task)
329{
330 struct signal_struct *sig = task->signal;
331 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
332
333 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
334
335 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
336
337 if (!consume)
338 return false;
339
340 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
341 sig->group_stop_count--;
342
343 /*
344 * Tell the caller to notify completion iff we are entering into a
345 * fresh group stop. Read comment in do_signal_stop() for details.
346 */
347 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
348 sig->flags = SIGNAL_STOP_STOPPED;
349 return true;
350 }
351 return false;
352}
353
354/*
355 * allocate a new signal queue record
356 * - this may be called without locks if and only if t == current, otherwise an
357 * appropriate lock must be held to stop the target task from exiting
358 */
359static struct sigqueue *
360__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
361{
362 struct sigqueue *q = NULL;
363 struct user_struct *user;
364
365 /*
366 * Protect access to @t credentials. This can go away when all
367 * callers hold rcu read lock.
368 */
369 rcu_read_lock();
370 user = get_uid(__task_cred(t)->user);
371 atomic_inc(&user->sigpending);
372 rcu_read_unlock();
373
374 if (override_rlimit ||
375 atomic_read(&user->sigpending) <=
376 task_rlimit(t, RLIMIT_SIGPENDING)) {
377 q = kmem_cache_alloc(sigqueue_cachep, flags);
378 } else {
379 print_dropped_signal(sig);
380 }
381
382 if (unlikely(q == NULL)) {
383 atomic_dec(&user->sigpending);
384 free_uid(user);
385 } else {
386 INIT_LIST_HEAD(&q->list);
387 q->flags = 0;
388 q->user = user;
389 }
390
391 return q;
392}
393
394static void __sigqueue_free(struct sigqueue *q)
395{
396 if (q->flags & SIGQUEUE_PREALLOC)
397 return;
398 atomic_dec(&q->user->sigpending);
399 free_uid(q->user);
400 kmem_cache_free(sigqueue_cachep, q);
401}
402
403void flush_sigqueue(struct sigpending *queue)
404{
405 struct sigqueue *q;
406
407 sigemptyset(&queue->signal);
408 while (!list_empty(&queue->list)) {
409 q = list_entry(queue->list.next, struct sigqueue , list);
410 list_del_init(&q->list);
411 __sigqueue_free(q);
412 }
413}
414
415/*
416 * Flush all pending signals for a task.
417 */
418void __flush_signals(struct task_struct *t)
419{
420 clear_tsk_thread_flag(t, TIF_SIGPENDING);
421 flush_sigqueue(&t->pending);
422 flush_sigqueue(&t->signal->shared_pending);
423}
424
425void flush_signals(struct task_struct *t)
426{
427 unsigned long flags;
428
429 spin_lock_irqsave(&t->sighand->siglock, flags);
430 __flush_signals(t);
431 spin_unlock_irqrestore(&t->sighand->siglock, flags);
432}
433
434static void __flush_itimer_signals(struct sigpending *pending)
435{
436 sigset_t signal, retain;
437 struct sigqueue *q, *n;
438
439 signal = pending->signal;
440 sigemptyset(&retain);
441
442 list_for_each_entry_safe(q, n, &pending->list, list) {
443 int sig = q->info.si_signo;
444
445 if (likely(q->info.si_code != SI_TIMER)) {
446 sigaddset(&retain, sig);
447 } else {
448 sigdelset(&signal, sig);
449 list_del_init(&q->list);
450 __sigqueue_free(q);
451 }
452 }
453
454 sigorsets(&pending->signal, &signal, &retain);
455}
456
457void flush_itimer_signals(void)
458{
459 struct task_struct *tsk = current;
460 unsigned long flags;
461
462 spin_lock_irqsave(&tsk->sighand->siglock, flags);
463 __flush_itimer_signals(&tsk->pending);
464 __flush_itimer_signals(&tsk->signal->shared_pending);
465 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
466}
467
468void ignore_signals(struct task_struct *t)
469{
470 int i;
471
472 for (i = 0; i < _NSIG; ++i)
473 t->sighand->action[i].sa.sa_handler = SIG_IGN;
474
475 flush_signals(t);
476}
477
478/*
479 * Flush all handlers for a task.
480 */
481
482void
483flush_signal_handlers(struct task_struct *t, int force_default)
484{
485 int i;
486 struct k_sigaction *ka = &t->sighand->action[0];
487 for (i = _NSIG ; i != 0 ; i--) {
488 if (force_default || ka->sa.sa_handler != SIG_IGN)
489 ka->sa.sa_handler = SIG_DFL;
490 ka->sa.sa_flags = 0;
491#ifdef __ARCH_HAS_SA_RESTORER
492 ka->sa.sa_restorer = NULL;
493#endif
494 sigemptyset(&ka->sa.sa_mask);
495 ka++;
496 }
497}
498
499int unhandled_signal(struct task_struct *tsk, int sig)
500{
501 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
502 if (is_global_init(tsk))
503 return 1;
504 if (handler != SIG_IGN && handler != SIG_DFL)
505 return 0;
506 /* if ptraced, let the tracer determine */
507 return !tsk->ptrace;
508}
509
510/*
511 * Notify the system that a driver wants to block all signals for this
512 * process, and wants to be notified if any signals at all were to be
513 * sent/acted upon. If the notifier routine returns non-zero, then the
514 * signal will be acted upon after all. If the notifier routine returns 0,
515 * then then signal will be blocked. Only one block per process is
516 * allowed. priv is a pointer to private data that the notifier routine
517 * can use to determine if the signal should be blocked or not.
518 */
519void
520block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
521{
522 unsigned long flags;
523
524 spin_lock_irqsave(¤t->sighand->siglock, flags);
525 current->notifier_mask = mask;
526 current->notifier_data = priv;
527 current->notifier = notifier;
528 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
529}
530
531/* Notify the system that blocking has ended. */
532
533void
534unblock_all_signals(void)
535{
536 unsigned long flags;
537
538 spin_lock_irqsave(¤t->sighand->siglock, flags);
539 current->notifier = NULL;
540 current->notifier_data = NULL;
541 recalc_sigpending();
542 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
543}
544
545static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
546{
547 struct sigqueue *q, *first = NULL;
548
549 /*
550 * Collect the siginfo appropriate to this signal. Check if
551 * there is another siginfo for the same signal.
552 */
553 list_for_each_entry(q, &list->list, list) {
554 if (q->info.si_signo == sig) {
555 if (first)
556 goto still_pending;
557 first = q;
558 }
559 }
560
561 sigdelset(&list->signal, sig);
562
563 if (first) {
564still_pending:
565 list_del_init(&first->list);
566 copy_siginfo(info, &first->info);
567 __sigqueue_free(first);
568 } else {
569 /*
570 * Ok, it wasn't in the queue. This must be
571 * a fast-pathed signal or we must have been
572 * out of queue space. So zero out the info.
573 */
574 info->si_signo = sig;
575 info->si_errno = 0;
576 info->si_code = SI_USER;
577 info->si_pid = 0;
578 info->si_uid = 0;
579 }
580}
581
582static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
583 siginfo_t *info)
584{
585 int sig = next_signal(pending, mask);
586
587 if (sig) {
588 if (current->notifier) {
589 if (sigismember(current->notifier_mask, sig)) {
590 if (!(current->notifier)(current->notifier_data)) {
591 clear_thread_flag(TIF_SIGPENDING);
592 return 0;
593 }
594 }
595 }
596
597 collect_signal(sig, pending, info);
598 }
599
600 return sig;
601}
602
603/*
604 * Dequeue a signal and return the element to the caller, which is
605 * expected to free it.
606 *
607 * All callers have to hold the siglock.
608 */
609int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
610{
611 int signr;
612
613 /* We only dequeue private signals from ourselves, we don't let
614 * signalfd steal them
615 */
616 signr = __dequeue_signal(&tsk->pending, mask, info);
617 if (!signr) {
618 signr = __dequeue_signal(&tsk->signal->shared_pending,
619 mask, info);
620 /*
621 * itimer signal ?
622 *
623 * itimers are process shared and we restart periodic
624 * itimers in the signal delivery path to prevent DoS
625 * attacks in the high resolution timer case. This is
626 * compliant with the old way of self-restarting
627 * itimers, as the SIGALRM is a legacy signal and only
628 * queued once. Changing the restart behaviour to
629 * restart the timer in the signal dequeue path is
630 * reducing the timer noise on heavy loaded !highres
631 * systems too.
632 */
633 if (unlikely(signr == SIGALRM)) {
634 struct hrtimer *tmr = &tsk->signal->real_timer;
635
636 if (!hrtimer_is_queued(tmr) &&
637 tsk->signal->it_real_incr.tv64 != 0) {
638 hrtimer_forward(tmr, tmr->base->get_time(),
639 tsk->signal->it_real_incr);
640 hrtimer_restart(tmr);
641 }
642 }
643 }
644
645 recalc_sigpending();
646 if (!signr)
647 return 0;
648
649 if (unlikely(sig_kernel_stop(signr))) {
650 /*
651 * Set a marker that we have dequeued a stop signal. Our
652 * caller might release the siglock and then the pending
653 * stop signal it is about to process is no longer in the
654 * pending bitmasks, but must still be cleared by a SIGCONT
655 * (and overruled by a SIGKILL). So those cases clear this
656 * shared flag after we've set it. Note that this flag may
657 * remain set after the signal we return is ignored or
658 * handled. That doesn't matter because its only purpose
659 * is to alert stop-signal processing code when another
660 * processor has come along and cleared the flag.
661 */
662 current->jobctl |= JOBCTL_STOP_DEQUEUED;
663 }
664 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
665 /*
666 * Release the siglock to ensure proper locking order
667 * of timer locks outside of siglocks. Note, we leave
668 * irqs disabled here, since the posix-timers code is
669 * about to disable them again anyway.
670 */
671 spin_unlock(&tsk->sighand->siglock);
672 do_schedule_next_timer(info);
673 spin_lock(&tsk->sighand->siglock);
674 }
675 return signr;
676}
677
678/*
679 * Tell a process that it has a new active signal..
680 *
681 * NOTE! we rely on the previous spin_lock to
682 * lock interrupts for us! We can only be called with
683 * "siglock" held, and the local interrupt must
684 * have been disabled when that got acquired!
685 *
686 * No need to set need_resched since signal event passing
687 * goes through ->blocked
688 */
689void signal_wake_up_state(struct task_struct *t, unsigned int state)
690{
691 set_tsk_thread_flag(t, TIF_SIGPENDING);
692 /*
693 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
694 * case. We don't check t->state here because there is a race with it
695 * executing another processor and just now entering stopped state.
696 * By using wake_up_state, we ensure the process will wake up and
697 * handle its death signal.
698 */
699 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
700 kick_process(t);
701}
702
703/*
704 * Remove signals in mask from the pending set and queue.
705 * Returns 1 if any signals were found.
706 *
707 * All callers must be holding the siglock.
708 *
709 * This version takes a sigset mask and looks at all signals,
710 * not just those in the first mask word.
711 */
712static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
713{
714 struct sigqueue *q, *n;
715 sigset_t m;
716
717 sigandsets(&m, mask, &s->signal);
718 if (sigisemptyset(&m))
719 return 0;
720
721 sigandnsets(&s->signal, &s->signal, mask);
722 list_for_each_entry_safe(q, n, &s->list, list) {
723 if (sigismember(mask, q->info.si_signo)) {
724 list_del_init(&q->list);
725 __sigqueue_free(q);
726 }
727 }
728 return 1;
729}
730/*
731 * Remove signals in mask from the pending set and queue.
732 * Returns 1 if any signals were found.
733 *
734 * All callers must be holding the siglock.
735 */
736static int rm_from_queue(unsigned long mask, struct sigpending *s)
737{
738 struct sigqueue *q, *n;
739
740 if (!sigtestsetmask(&s->signal, mask))
741 return 0;
742
743 sigdelsetmask(&s->signal, mask);
744 list_for_each_entry_safe(q, n, &s->list, list) {
745 if (q->info.si_signo < SIGRTMIN &&
746 (mask & sigmask(q->info.si_signo))) {
747 list_del_init(&q->list);
748 __sigqueue_free(q);
749 }
750 }
751 return 1;
752}
753
754static inline int is_si_special(const struct siginfo *info)
755{
756 return info <= SEND_SIG_FORCED;
757}
758
759static inline bool si_fromuser(const struct siginfo *info)
760{
761 return info == SEND_SIG_NOINFO ||
762 (!is_si_special(info) && SI_FROMUSER(info));
763}
764
765/*
766 * called with RCU read lock from check_kill_permission()
767 */
768static int kill_ok_by_cred(struct task_struct *t)
769{
770 const struct cred *cred = current_cred();
771 const struct cred *tcred = __task_cred(t);
772
773 if (uid_eq(cred->euid, tcred->suid) ||
774 uid_eq(cred->euid, tcred->uid) ||
775 uid_eq(cred->uid, tcred->suid) ||
776 uid_eq(cred->uid, tcred->uid))
777 return 1;
778
779 if (ns_capable(tcred->user_ns, CAP_KILL))
780 return 1;
781
782 return 0;
783}
784
785/*
786 * Bad permissions for sending the signal
787 * - the caller must hold the RCU read lock
788 */
789static int check_kill_permission(int sig, struct siginfo *info,
790 struct task_struct *t)
791{
792 struct pid *sid;
793 int error;
794
795 if (!valid_signal(sig))
796 return -EINVAL;
797
798 if (!si_fromuser(info))
799 return 0;
800
801 error = audit_signal_info(sig, t); /* Let audit system see the signal */
802 if (error)
803 return error;
804
805 if (!same_thread_group(current, t) &&
806 !kill_ok_by_cred(t)) {
807 switch (sig) {
808 case SIGCONT:
809 sid = task_session(t);
810 /*
811 * We don't return the error if sid == NULL. The
812 * task was unhashed, the caller must notice this.
813 */
814 if (!sid || sid == task_session(current))
815 break;
816 default:
817 return -EPERM;
818 }
819 }
820
821 return security_task_kill(t, info, sig, 0);
822}
823
824/**
825 * ptrace_trap_notify - schedule trap to notify ptracer
826 * @t: tracee wanting to notify tracer
827 *
828 * This function schedules sticky ptrace trap which is cleared on the next
829 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
830 * ptracer.
831 *
832 * If @t is running, STOP trap will be taken. If trapped for STOP and
833 * ptracer is listening for events, tracee is woken up so that it can
834 * re-trap for the new event. If trapped otherwise, STOP trap will be
835 * eventually taken without returning to userland after the existing traps
836 * are finished by PTRACE_CONT.
837 *
838 * CONTEXT:
839 * Must be called with @task->sighand->siglock held.
840 */
841static void ptrace_trap_notify(struct task_struct *t)
842{
843 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
844 assert_spin_locked(&t->sighand->siglock);
845
846 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
847 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
848}
849
850/*
851 * Handle magic process-wide effects of stop/continue signals. Unlike
852 * the signal actions, these happen immediately at signal-generation
853 * time regardless of blocking, ignoring, or handling. This does the
854 * actual continuing for SIGCONT, but not the actual stopping for stop
855 * signals. The process stop is done as a signal action for SIG_DFL.
856 *
857 * Returns true if the signal should be actually delivered, otherwise
858 * it should be dropped.
859 */
860static bool prepare_signal(int sig, struct task_struct *p, bool force)
861{
862 struct signal_struct *signal = p->signal;
863 struct task_struct *t;
864
865 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
866 if (signal->flags & SIGNAL_GROUP_COREDUMP)
867 return sig == SIGKILL;
868 /*
869 * The process is in the middle of dying, nothing to do.
870 */
871 } else if (sig_kernel_stop(sig)) {
872 /*
873 * This is a stop signal. Remove SIGCONT from all queues.
874 */
875 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
876 t = p;
877 do {
878 rm_from_queue(sigmask(SIGCONT), &t->pending);
879 } while_each_thread(p, t);
880 } else if (sig == SIGCONT) {
881 unsigned int why;
882 /*
883 * Remove all stop signals from all queues, wake all threads.
884 */
885 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
886 t = p;
887 do {
888 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
889 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
890 if (likely(!(t->ptrace & PT_SEIZED)))
891 wake_up_state(t, __TASK_STOPPED);
892 else
893 ptrace_trap_notify(t);
894 } while_each_thread(p, t);
895
896 /*
897 * Notify the parent with CLD_CONTINUED if we were stopped.
898 *
899 * If we were in the middle of a group stop, we pretend it
900 * was already finished, and then continued. Since SIGCHLD
901 * doesn't queue we report only CLD_STOPPED, as if the next
902 * CLD_CONTINUED was dropped.
903 */
904 why = 0;
905 if (signal->flags & SIGNAL_STOP_STOPPED)
906 why |= SIGNAL_CLD_CONTINUED;
907 else if (signal->group_stop_count)
908 why |= SIGNAL_CLD_STOPPED;
909
910 if (why) {
911 /*
912 * The first thread which returns from do_signal_stop()
913 * will take ->siglock, notice SIGNAL_CLD_MASK, and
914 * notify its parent. See get_signal_to_deliver().
915 */
916 signal->flags = why | SIGNAL_STOP_CONTINUED;
917 signal->group_stop_count = 0;
918 signal->group_exit_code = 0;
919 }
920 }
921
922 return !sig_ignored(p, sig, force);
923}
924
925/*
926 * Test if P wants to take SIG. After we've checked all threads with this,
927 * it's equivalent to finding no threads not blocking SIG. Any threads not
928 * blocking SIG were ruled out because they are not running and already
929 * have pending signals. Such threads will dequeue from the shared queue
930 * as soon as they're available, so putting the signal on the shared queue
931 * will be equivalent to sending it to one such thread.
932 */
933static inline int wants_signal(int sig, struct task_struct *p)
934{
935 if (sigismember(&p->blocked, sig))
936 return 0;
937 if (p->flags & PF_EXITING)
938 return 0;
939 if (sig == SIGKILL)
940 return 1;
941 if (task_is_stopped_or_traced(p))
942 return 0;
943 return task_curr(p) || !signal_pending(p);
944}
945
946static void complete_signal(int sig, struct task_struct *p, int group)
947{
948 struct signal_struct *signal = p->signal;
949 struct task_struct *t;
950
951 /*
952 * Now find a thread we can wake up to take the signal off the queue.
953 *
954 * If the main thread wants the signal, it gets first crack.
955 * Probably the least surprising to the average bear.
956 */
957 if (wants_signal(sig, p))
958 t = p;
959 else if (!group || thread_group_empty(p))
960 /*
961 * There is just one thread and it does not need to be woken.
962 * It will dequeue unblocked signals before it runs again.
963 */
964 return;
965 else {
966 /*
967 * Otherwise try to find a suitable thread.
968 */
969 t = signal->curr_target;
970 while (!wants_signal(sig, t)) {
971 t = next_thread(t);
972 if (t == signal->curr_target)
973 /*
974 * No thread needs to be woken.
975 * Any eligible threads will see
976 * the signal in the queue soon.
977 */
978 return;
979 }
980 signal->curr_target = t;
981 }
982
983 /*
984 * Found a killable thread. If the signal will be fatal,
985 * then start taking the whole group down immediately.
986 */
987 if (sig_fatal(p, sig) &&
988 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
989 !sigismember(&t->real_blocked, sig) &&
990 (sig == SIGKILL || !t->ptrace)) {
991 /*
992 * This signal will be fatal to the whole group.
993 */
994 if (!sig_kernel_coredump(sig)) {
995 /*
996 * Start a group exit and wake everybody up.
997 * This way we don't have other threads
998 * running and doing things after a slower
999 * thread has the fatal signal pending.
1000 */
1001 signal->flags = SIGNAL_GROUP_EXIT;
1002 signal->group_exit_code = sig;
1003 signal->group_stop_count = 0;
1004 t = p;
1005 do {
1006 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1007 sigaddset(&t->pending.signal, SIGKILL);
1008 signal_wake_up(t, 1);
1009 } while_each_thread(p, t);
1010 return;
1011 }
1012 }
1013
1014 /*
1015 * The signal is already in the shared-pending queue.
1016 * Tell the chosen thread to wake up and dequeue it.
1017 */
1018 signal_wake_up(t, sig == SIGKILL);
1019 return;
1020}
1021
1022static inline int legacy_queue(struct sigpending *signals, int sig)
1023{
1024 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1025}
1026
1027#ifdef CONFIG_USER_NS
1028static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1029{
1030 if (current_user_ns() == task_cred_xxx(t, user_ns))
1031 return;
1032
1033 if (SI_FROMKERNEL(info))
1034 return;
1035
1036 rcu_read_lock();
1037 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1038 make_kuid(current_user_ns(), info->si_uid));
1039 rcu_read_unlock();
1040}
1041#else
1042static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1043{
1044 return;
1045}
1046#endif
1047
1048static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1049 int group, int from_ancestor_ns)
1050{
1051 struct sigpending *pending;
1052 struct sigqueue *q;
1053 int override_rlimit;
1054 int ret = 0, result;
1055
1056 assert_spin_locked(&t->sighand->siglock);
1057
1058 result = TRACE_SIGNAL_IGNORED;
1059 if (!prepare_signal(sig, t,
1060 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1061 goto ret;
1062
1063 pending = group ? &t->signal->shared_pending : &t->pending;
1064 /*
1065 * Short-circuit ignored signals and support queuing
1066 * exactly one non-rt signal, so that we can get more
1067 * detailed information about the cause of the signal.
1068 */
1069 result = TRACE_SIGNAL_ALREADY_PENDING;
1070 if (legacy_queue(pending, sig))
1071 goto ret;
1072
1073 result = TRACE_SIGNAL_DELIVERED;
1074 /*
1075 * fast-pathed signals for kernel-internal things like SIGSTOP
1076 * or SIGKILL.
1077 */
1078 if (info == SEND_SIG_FORCED)
1079 goto out_set;
1080
1081 /*
1082 * Real-time signals must be queued if sent by sigqueue, or
1083 * some other real-time mechanism. It is implementation
1084 * defined whether kill() does so. We attempt to do so, on
1085 * the principle of least surprise, but since kill is not
1086 * allowed to fail with EAGAIN when low on memory we just
1087 * make sure at least one signal gets delivered and don't
1088 * pass on the info struct.
1089 */
1090 if (sig < SIGRTMIN)
1091 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1092 else
1093 override_rlimit = 0;
1094
1095 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1096 override_rlimit);
1097 if (q) {
1098 list_add_tail(&q->list, &pending->list);
1099 switch ((unsigned long) info) {
1100 case (unsigned long) SEND_SIG_NOINFO:
1101 q->info.si_signo = sig;
1102 q->info.si_errno = 0;
1103 q->info.si_code = SI_USER;
1104 q->info.si_pid = task_tgid_nr_ns(current,
1105 task_active_pid_ns(t));
1106 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1107 break;
1108 case (unsigned long) SEND_SIG_PRIV:
1109 q->info.si_signo = sig;
1110 q->info.si_errno = 0;
1111 q->info.si_code = SI_KERNEL;
1112 q->info.si_pid = 0;
1113 q->info.si_uid = 0;
1114 break;
1115 default:
1116 copy_siginfo(&q->info, info);
1117 if (from_ancestor_ns)
1118 q->info.si_pid = 0;
1119 break;
1120 }
1121
1122 userns_fixup_signal_uid(&q->info, t);
1123
1124 } else if (!is_si_special(info)) {
1125 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1126 /*
1127 * Queue overflow, abort. We may abort if the
1128 * signal was rt and sent by user using something
1129 * other than kill().
1130 */
1131 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1132 ret = -EAGAIN;
1133 goto ret;
1134 } else {
1135 /*
1136 * This is a silent loss of information. We still
1137 * send the signal, but the *info bits are lost.
1138 */
1139 result = TRACE_SIGNAL_LOSE_INFO;
1140 }
1141 }
1142
1143out_set:
1144 signalfd_notify(t, sig);
1145 sigaddset(&pending->signal, sig);
1146 complete_signal(sig, t, group);
1147ret:
1148 trace_signal_generate(sig, info, t, group, result);
1149 return ret;
1150}
1151
1152static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1153 int group)
1154{
1155 int from_ancestor_ns = 0;
1156
1157#ifdef CONFIG_PID_NS
1158 from_ancestor_ns = si_fromuser(info) &&
1159 !task_pid_nr_ns(current, task_active_pid_ns(t));
1160#endif
1161
1162 return __send_signal(sig, info, t, group, from_ancestor_ns);
1163}
1164
1165static void print_fatal_signal(int signr)
1166{
1167 struct pt_regs *regs = signal_pt_regs();
1168 printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1169
1170#if defined(__i386__) && !defined(__arch_um__)
1171 printk(KERN_INFO "code at %08lx: ", regs->ip);
1172 {
1173 int i;
1174 for (i = 0; i < 16; i++) {
1175 unsigned char insn;
1176
1177 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1178 break;
1179 printk(KERN_CONT "%02x ", insn);
1180 }
1181 }
1182 printk(KERN_CONT "\n");
1183#endif
1184 preempt_disable();
1185 show_regs(regs);
1186 preempt_enable();
1187}
1188
1189static int __init setup_print_fatal_signals(char *str)
1190{
1191 get_option (&str, &print_fatal_signals);
1192
1193 return 1;
1194}
1195
1196__setup("print-fatal-signals=", setup_print_fatal_signals);
1197
1198int
1199__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1200{
1201 return send_signal(sig, info, p, 1);
1202}
1203
1204static int
1205specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1206{
1207 return send_signal(sig, info, t, 0);
1208}
1209
1210int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1211 bool group)
1212{
1213 unsigned long flags;
1214 int ret = -ESRCH;
1215
1216 if (lock_task_sighand(p, &flags)) {
1217 ret = send_signal(sig, info, p, group);
1218 unlock_task_sighand(p, &flags);
1219 }
1220
1221 return ret;
1222}
1223
1224/*
1225 * Force a signal that the process can't ignore: if necessary
1226 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1227 *
1228 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1229 * since we do not want to have a signal handler that was blocked
1230 * be invoked when user space had explicitly blocked it.
1231 *
1232 * We don't want to have recursive SIGSEGV's etc, for example,
1233 * that is why we also clear SIGNAL_UNKILLABLE.
1234 */
1235int
1236force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1237{
1238 unsigned long int flags;
1239 int ret, blocked, ignored;
1240 struct k_sigaction *action;
1241
1242 spin_lock_irqsave(&t->sighand->siglock, flags);
1243 action = &t->sighand->action[sig-1];
1244 ignored = action->sa.sa_handler == SIG_IGN;
1245 blocked = sigismember(&t->blocked, sig);
1246 if (blocked || ignored) {
1247 action->sa.sa_handler = SIG_DFL;
1248 if (blocked) {
1249 sigdelset(&t->blocked, sig);
1250 recalc_sigpending_and_wake(t);
1251 }
1252 }
1253 if (action->sa.sa_handler == SIG_DFL)
1254 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1255 ret = specific_send_sig_info(sig, info, t);
1256 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1257
1258 return ret;
1259}
1260
1261/*
1262 * Nuke all other threads in the group.
1263 */
1264int zap_other_threads(struct task_struct *p)
1265{
1266 struct task_struct *t = p;
1267 int count = 0;
1268
1269 p->signal->group_stop_count = 0;
1270
1271 while_each_thread(p, t) {
1272 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1273 count++;
1274
1275 /* Don't bother with already dead threads */
1276 if (t->exit_state)
1277 continue;
1278 sigaddset(&t->pending.signal, SIGKILL);
1279 signal_wake_up(t, 1);
1280 }
1281
1282 return count;
1283}
1284
1285struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1286 unsigned long *flags)
1287{
1288 struct sighand_struct *sighand;
1289
1290 for (;;) {
1291 local_irq_save(*flags);
1292 rcu_read_lock();
1293 sighand = rcu_dereference(tsk->sighand);
1294 if (unlikely(sighand == NULL)) {
1295 rcu_read_unlock();
1296 local_irq_restore(*flags);
1297 break;
1298 }
1299
1300 spin_lock(&sighand->siglock);
1301 if (likely(sighand == tsk->sighand)) {
1302 rcu_read_unlock();
1303 break;
1304 }
1305 spin_unlock(&sighand->siglock);
1306 rcu_read_unlock();
1307 local_irq_restore(*flags);
1308 }
1309
1310 return sighand;
1311}
1312
1313/*
1314 * send signal info to all the members of a group
1315 */
1316int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1317{
1318 int ret;
1319
1320 rcu_read_lock();
1321 ret = check_kill_permission(sig, info, p);
1322 rcu_read_unlock();
1323
1324 if (!ret && sig)
1325 ret = do_send_sig_info(sig, info, p, true);
1326
1327 return ret;
1328}
1329
1330/*
1331 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1332 * control characters do (^C, ^Z etc)
1333 * - the caller must hold at least a readlock on tasklist_lock
1334 */
1335int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1336{
1337 struct task_struct *p = NULL;
1338 int retval, success;
1339
1340 success = 0;
1341 retval = -ESRCH;
1342 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1343 int err = group_send_sig_info(sig, info, p);
1344 success |= !err;
1345 retval = err;
1346 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1347 return success ? 0 : retval;
1348}
1349
1350int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1351{
1352 int error = -ESRCH;
1353 struct task_struct *p;
1354
1355 rcu_read_lock();
1356retry:
1357 p = pid_task(pid, PIDTYPE_PID);
1358 if (p) {
1359 error = group_send_sig_info(sig, info, p);
1360 if (unlikely(error == -ESRCH))
1361 /*
1362 * The task was unhashed in between, try again.
1363 * If it is dead, pid_task() will return NULL,
1364 * if we race with de_thread() it will find the
1365 * new leader.
1366 */
1367 goto retry;
1368 }
1369 rcu_read_unlock();
1370
1371 return error;
1372}
1373
1374int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1375{
1376 int error;
1377 rcu_read_lock();
1378 error = kill_pid_info(sig, info, find_vpid(pid));
1379 rcu_read_unlock();
1380 return error;
1381}
1382
1383static int kill_as_cred_perm(const struct cred *cred,
1384 struct task_struct *target)
1385{
1386 const struct cred *pcred = __task_cred(target);
1387 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1388 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1389 return 0;
1390 return 1;
1391}
1392
1393/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1394int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1395 const struct cred *cred, u32 secid)
1396{
1397 int ret = -EINVAL;
1398 struct task_struct *p;
1399 unsigned long flags;
1400
1401 if (!valid_signal(sig))
1402 return ret;
1403
1404 rcu_read_lock();
1405 p = pid_task(pid, PIDTYPE_PID);
1406 if (!p) {
1407 ret = -ESRCH;
1408 goto out_unlock;
1409 }
1410 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1411 ret = -EPERM;
1412 goto out_unlock;
1413 }
1414 ret = security_task_kill(p, info, sig, secid);
1415 if (ret)
1416 goto out_unlock;
1417
1418 if (sig) {
1419 if (lock_task_sighand(p, &flags)) {
1420 ret = __send_signal(sig, info, p, 1, 0);
1421 unlock_task_sighand(p, &flags);
1422 } else
1423 ret = -ESRCH;
1424 }
1425out_unlock:
1426 rcu_read_unlock();
1427 return ret;
1428}
1429EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1430
1431/*
1432 * kill_something_info() interprets pid in interesting ways just like kill(2).
1433 *
1434 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1435 * is probably wrong. Should make it like BSD or SYSV.
1436 */
1437
1438static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1439{
1440 int ret;
1441
1442 if (pid > 0) {
1443 rcu_read_lock();
1444 ret = kill_pid_info(sig, info, find_vpid(pid));
1445 rcu_read_unlock();
1446 return ret;
1447 }
1448
1449 read_lock(&tasklist_lock);
1450 if (pid != -1) {
1451 ret = __kill_pgrp_info(sig, info,
1452 pid ? find_vpid(-pid) : task_pgrp(current));
1453 } else {
1454 int retval = 0, count = 0;
1455 struct task_struct * p;
1456
1457 for_each_process(p) {
1458 if (task_pid_vnr(p) > 1 &&
1459 !same_thread_group(p, current)) {
1460 int err = group_send_sig_info(sig, info, p);
1461 ++count;
1462 if (err != -EPERM)
1463 retval = err;
1464 }
1465 }
1466 ret = count ? retval : -ESRCH;
1467 }
1468 read_unlock(&tasklist_lock);
1469
1470 return ret;
1471}
1472
1473/*
1474 * These are for backward compatibility with the rest of the kernel source.
1475 */
1476
1477int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1478{
1479 /*
1480 * Make sure legacy kernel users don't send in bad values
1481 * (normal paths check this in check_kill_permission).
1482 */
1483 if (!valid_signal(sig))
1484 return -EINVAL;
1485
1486 return do_send_sig_info(sig, info, p, false);
1487}
1488
1489#define __si_special(priv) \
1490 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1491
1492int
1493send_sig(int sig, struct task_struct *p, int priv)
1494{
1495 return send_sig_info(sig, __si_special(priv), p);
1496}
1497
1498void
1499force_sig(int sig, struct task_struct *p)
1500{
1501 force_sig_info(sig, SEND_SIG_PRIV, p);
1502}
1503
1504/*
1505 * When things go south during signal handling, we
1506 * will force a SIGSEGV. And if the signal that caused
1507 * the problem was already a SIGSEGV, we'll want to
1508 * make sure we don't even try to deliver the signal..
1509 */
1510int
1511force_sigsegv(int sig, struct task_struct *p)
1512{
1513 if (sig == SIGSEGV) {
1514 unsigned long flags;
1515 spin_lock_irqsave(&p->sighand->siglock, flags);
1516 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1517 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1518 }
1519 force_sig(SIGSEGV, p);
1520 return 0;
1521}
1522
1523int kill_pgrp(struct pid *pid, int sig, int priv)
1524{
1525 int ret;
1526
1527 read_lock(&tasklist_lock);
1528 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1529 read_unlock(&tasklist_lock);
1530
1531 return ret;
1532}
1533EXPORT_SYMBOL(kill_pgrp);
1534
1535int kill_pid(struct pid *pid, int sig, int priv)
1536{
1537 return kill_pid_info(sig, __si_special(priv), pid);
1538}
1539EXPORT_SYMBOL(kill_pid);
1540
1541/*
1542 * These functions support sending signals using preallocated sigqueue
1543 * structures. This is needed "because realtime applications cannot
1544 * afford to lose notifications of asynchronous events, like timer
1545 * expirations or I/O completions". In the case of POSIX Timers
1546 * we allocate the sigqueue structure from the timer_create. If this
1547 * allocation fails we are able to report the failure to the application
1548 * with an EAGAIN error.
1549 */
1550struct sigqueue *sigqueue_alloc(void)
1551{
1552 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1553
1554 if (q)
1555 q->flags |= SIGQUEUE_PREALLOC;
1556
1557 return q;
1558}
1559
1560void sigqueue_free(struct sigqueue *q)
1561{
1562 unsigned long flags;
1563 spinlock_t *lock = ¤t->sighand->siglock;
1564
1565 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1566 /*
1567 * We must hold ->siglock while testing q->list
1568 * to serialize with collect_signal() or with
1569 * __exit_signal()->flush_sigqueue().
1570 */
1571 spin_lock_irqsave(lock, flags);
1572 q->flags &= ~SIGQUEUE_PREALLOC;
1573 /*
1574 * If it is queued it will be freed when dequeued,
1575 * like the "regular" sigqueue.
1576 */
1577 if (!list_empty(&q->list))
1578 q = NULL;
1579 spin_unlock_irqrestore(lock, flags);
1580
1581 if (q)
1582 __sigqueue_free(q);
1583}
1584
1585int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1586{
1587 int sig = q->info.si_signo;
1588 struct sigpending *pending;
1589 unsigned long flags;
1590 int ret, result;
1591
1592 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1593
1594 ret = -1;
1595 if (!likely(lock_task_sighand(t, &flags)))
1596 goto ret;
1597
1598 ret = 1; /* the signal is ignored */
1599 result = TRACE_SIGNAL_IGNORED;
1600 if (!prepare_signal(sig, t, false))
1601 goto out;
1602
1603 ret = 0;
1604 if (unlikely(!list_empty(&q->list))) {
1605 /*
1606 * If an SI_TIMER entry is already queue just increment
1607 * the overrun count.
1608 */
1609 BUG_ON(q->info.si_code != SI_TIMER);
1610 q->info.si_overrun++;
1611 result = TRACE_SIGNAL_ALREADY_PENDING;
1612 goto out;
1613 }
1614 q->info.si_overrun = 0;
1615
1616 signalfd_notify(t, sig);
1617 pending = group ? &t->signal->shared_pending : &t->pending;
1618 list_add_tail(&q->list, &pending->list);
1619 sigaddset(&pending->signal, sig);
1620 complete_signal(sig, t, group);
1621 result = TRACE_SIGNAL_DELIVERED;
1622out:
1623 trace_signal_generate(sig, &q->info, t, group, result);
1624 unlock_task_sighand(t, &flags);
1625ret:
1626 return ret;
1627}
1628
1629/*
1630 * Let a parent know about the death of a child.
1631 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1632 *
1633 * Returns true if our parent ignored us and so we've switched to
1634 * self-reaping.
1635 */
1636bool do_notify_parent(struct task_struct *tsk, int sig)
1637{
1638 struct siginfo info;
1639 unsigned long flags;
1640 struct sighand_struct *psig;
1641 bool autoreap = false;
1642 cputime_t utime, stime;
1643
1644 BUG_ON(sig == -1);
1645
1646 /* do_notify_parent_cldstop should have been called instead. */
1647 BUG_ON(task_is_stopped_or_traced(tsk));
1648
1649 BUG_ON(!tsk->ptrace &&
1650 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1651
1652 if (sig != SIGCHLD) {
1653 /*
1654 * This is only possible if parent == real_parent.
1655 * Check if it has changed security domain.
1656 */
1657 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1658 sig = SIGCHLD;
1659 }
1660
1661 info.si_signo = sig;
1662 info.si_errno = 0;
1663 /*
1664 * We are under tasklist_lock here so our parent is tied to
1665 * us and cannot change.
1666 *
1667 * task_active_pid_ns will always return the same pid namespace
1668 * until a task passes through release_task.
1669 *
1670 * write_lock() currently calls preempt_disable() which is the
1671 * same as rcu_read_lock(), but according to Oleg, this is not
1672 * correct to rely on this
1673 */
1674 rcu_read_lock();
1675 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1676 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1677 task_uid(tsk));
1678 rcu_read_unlock();
1679
1680 task_cputime(tsk, &utime, &stime);
1681 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1682 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1683
1684 info.si_status = tsk->exit_code & 0x7f;
1685 if (tsk->exit_code & 0x80)
1686 info.si_code = CLD_DUMPED;
1687 else if (tsk->exit_code & 0x7f)
1688 info.si_code = CLD_KILLED;
1689 else {
1690 info.si_code = CLD_EXITED;
1691 info.si_status = tsk->exit_code >> 8;
1692 }
1693
1694 psig = tsk->parent->sighand;
1695 spin_lock_irqsave(&psig->siglock, flags);
1696 if (!tsk->ptrace && sig == SIGCHLD &&
1697 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1698 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1699 /*
1700 * We are exiting and our parent doesn't care. POSIX.1
1701 * defines special semantics for setting SIGCHLD to SIG_IGN
1702 * or setting the SA_NOCLDWAIT flag: we should be reaped
1703 * automatically and not left for our parent's wait4 call.
1704 * Rather than having the parent do it as a magic kind of
1705 * signal handler, we just set this to tell do_exit that we
1706 * can be cleaned up without becoming a zombie. Note that
1707 * we still call __wake_up_parent in this case, because a
1708 * blocked sys_wait4 might now return -ECHILD.
1709 *
1710 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1711 * is implementation-defined: we do (if you don't want
1712 * it, just use SIG_IGN instead).
1713 */
1714 autoreap = true;
1715 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1716 sig = 0;
1717 }
1718 if (valid_signal(sig) && sig)
1719 __group_send_sig_info(sig, &info, tsk->parent);
1720 __wake_up_parent(tsk, tsk->parent);
1721 spin_unlock_irqrestore(&psig->siglock, flags);
1722
1723 return autoreap;
1724}
1725
1726/**
1727 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1728 * @tsk: task reporting the state change
1729 * @for_ptracer: the notification is for ptracer
1730 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1731 *
1732 * Notify @tsk's parent that the stopped/continued state has changed. If
1733 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1734 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1735 *
1736 * CONTEXT:
1737 * Must be called with tasklist_lock at least read locked.
1738 */
1739static void do_notify_parent_cldstop(struct task_struct *tsk,
1740 bool for_ptracer, int why)
1741{
1742 struct siginfo info;
1743 unsigned long flags;
1744 struct task_struct *parent;
1745 struct sighand_struct *sighand;
1746 cputime_t utime, stime;
1747
1748 if (for_ptracer) {
1749 parent = tsk->parent;
1750 } else {
1751 tsk = tsk->group_leader;
1752 parent = tsk->real_parent;
1753 }
1754
1755 info.si_signo = SIGCHLD;
1756 info.si_errno = 0;
1757 /*
1758 * see comment in do_notify_parent() about the following 4 lines
1759 */
1760 rcu_read_lock();
1761 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1762 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1763 rcu_read_unlock();
1764
1765 task_cputime(tsk, &utime, &stime);
1766 info.si_utime = cputime_to_clock_t(utime);
1767 info.si_stime = cputime_to_clock_t(stime);
1768
1769 info.si_code = why;
1770 switch (why) {
1771 case CLD_CONTINUED:
1772 info.si_status = SIGCONT;
1773 break;
1774 case CLD_STOPPED:
1775 info.si_status = tsk->signal->group_exit_code & 0x7f;
1776 break;
1777 case CLD_TRAPPED:
1778 info.si_status = tsk->exit_code & 0x7f;
1779 break;
1780 default:
1781 BUG();
1782 }
1783
1784 sighand = parent->sighand;
1785 spin_lock_irqsave(&sighand->siglock, flags);
1786 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1787 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1788 __group_send_sig_info(SIGCHLD, &info, parent);
1789 /*
1790 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1791 */
1792 __wake_up_parent(tsk, parent);
1793 spin_unlock_irqrestore(&sighand->siglock, flags);
1794}
1795
1796static inline int may_ptrace_stop(void)
1797{
1798 if (!likely(current->ptrace))
1799 return 0;
1800 /*
1801 * Are we in the middle of do_coredump?
1802 * If so and our tracer is also part of the coredump stopping
1803 * is a deadlock situation, and pointless because our tracer
1804 * is dead so don't allow us to stop.
1805 * If SIGKILL was already sent before the caller unlocked
1806 * ->siglock we must see ->core_state != NULL. Otherwise it
1807 * is safe to enter schedule().
1808 *
1809 * This is almost outdated, a task with the pending SIGKILL can't
1810 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1811 * after SIGKILL was already dequeued.
1812 */
1813 if (unlikely(current->mm->core_state) &&
1814 unlikely(current->mm == current->parent->mm))
1815 return 0;
1816
1817 return 1;
1818}
1819
1820/*
1821 * Return non-zero if there is a SIGKILL that should be waking us up.
1822 * Called with the siglock held.
1823 */
1824static int sigkill_pending(struct task_struct *tsk)
1825{
1826 return sigismember(&tsk->pending.signal, SIGKILL) ||
1827 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1828}
1829
1830/*
1831 * This must be called with current->sighand->siglock held.
1832 *
1833 * This should be the path for all ptrace stops.
1834 * We always set current->last_siginfo while stopped here.
1835 * That makes it a way to test a stopped process for
1836 * being ptrace-stopped vs being job-control-stopped.
1837 *
1838 * If we actually decide not to stop at all because the tracer
1839 * is gone, we keep current->exit_code unless clear_code.
1840 */
1841static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1842 __releases(¤t->sighand->siglock)
1843 __acquires(¤t->sighand->siglock)
1844{
1845 bool gstop_done = false;
1846
1847 if (arch_ptrace_stop_needed(exit_code, info)) {
1848 /*
1849 * The arch code has something special to do before a
1850 * ptrace stop. This is allowed to block, e.g. for faults
1851 * on user stack pages. We can't keep the siglock while
1852 * calling arch_ptrace_stop, so we must release it now.
1853 * To preserve proper semantics, we must do this before
1854 * any signal bookkeeping like checking group_stop_count.
1855 * Meanwhile, a SIGKILL could come in before we retake the
1856 * siglock. That must prevent us from sleeping in TASK_TRACED.
1857 * So after regaining the lock, we must check for SIGKILL.
1858 */
1859 spin_unlock_irq(¤t->sighand->siglock);
1860 arch_ptrace_stop(exit_code, info);
1861 spin_lock_irq(¤t->sighand->siglock);
1862 if (sigkill_pending(current))
1863 return;
1864 }
1865
1866 /*
1867 * We're committing to trapping. TRACED should be visible before
1868 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1869 * Also, transition to TRACED and updates to ->jobctl should be
1870 * atomic with respect to siglock and should be done after the arch
1871 * hook as siglock is released and regrabbed across it.
1872 */
1873 set_current_state(TASK_TRACED);
1874
1875 current->last_siginfo = info;
1876 current->exit_code = exit_code;
1877
1878 /*
1879 * If @why is CLD_STOPPED, we're trapping to participate in a group
1880 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1881 * across siglock relocks since INTERRUPT was scheduled, PENDING
1882 * could be clear now. We act as if SIGCONT is received after
1883 * TASK_TRACED is entered - ignore it.
1884 */
1885 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1886 gstop_done = task_participate_group_stop(current);
1887
1888 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1889 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1890 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1891 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1892
1893 /* entering a trap, clear TRAPPING */
1894 task_clear_jobctl_trapping(current);
1895
1896 spin_unlock_irq(¤t->sighand->siglock);
1897 read_lock(&tasklist_lock);
1898 if (may_ptrace_stop()) {
1899 /*
1900 * Notify parents of the stop.
1901 *
1902 * While ptraced, there are two parents - the ptracer and
1903 * the real_parent of the group_leader. The ptracer should
1904 * know about every stop while the real parent is only
1905 * interested in the completion of group stop. The states
1906 * for the two don't interact with each other. Notify
1907 * separately unless they're gonna be duplicates.
1908 */
1909 do_notify_parent_cldstop(current, true, why);
1910 if (gstop_done && ptrace_reparented(current))
1911 do_notify_parent_cldstop(current, false, why);
1912
1913 /*
1914 * Don't want to allow preemption here, because
1915 * sys_ptrace() needs this task to be inactive.
1916 *
1917 * XXX: implement read_unlock_no_resched().
1918 */
1919 preempt_disable();
1920 read_unlock(&tasklist_lock);
1921 preempt_enable_no_resched();
1922 freezable_schedule();
1923 } else {
1924 /*
1925 * By the time we got the lock, our tracer went away.
1926 * Don't drop the lock yet, another tracer may come.
1927 *
1928 * If @gstop_done, the ptracer went away between group stop
1929 * completion and here. During detach, it would have set
1930 * JOBCTL_STOP_PENDING on us and we'll re-enter
1931 * TASK_STOPPED in do_signal_stop() on return, so notifying
1932 * the real parent of the group stop completion is enough.
1933 */
1934 if (gstop_done)
1935 do_notify_parent_cldstop(current, false, why);
1936
1937 /* tasklist protects us from ptrace_freeze_traced() */
1938 __set_current_state(TASK_RUNNING);
1939 if (clear_code)
1940 current->exit_code = 0;
1941 read_unlock(&tasklist_lock);
1942 }
1943
1944 /*
1945 * We are back. Now reacquire the siglock before touching
1946 * last_siginfo, so that we are sure to have synchronized with
1947 * any signal-sending on another CPU that wants to examine it.
1948 */
1949 spin_lock_irq(¤t->sighand->siglock);
1950 current->last_siginfo = NULL;
1951
1952 /* LISTENING can be set only during STOP traps, clear it */
1953 current->jobctl &= ~JOBCTL_LISTENING;
1954
1955 /*
1956 * Queued signals ignored us while we were stopped for tracing.
1957 * So check for any that we should take before resuming user mode.
1958 * This sets TIF_SIGPENDING, but never clears it.
1959 */
1960 recalc_sigpending_tsk(current);
1961}
1962
1963static void ptrace_do_notify(int signr, int exit_code, int why)
1964{
1965 siginfo_t info;
1966
1967 memset(&info, 0, sizeof info);
1968 info.si_signo = signr;
1969 info.si_code = exit_code;
1970 info.si_pid = task_pid_vnr(current);
1971 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1972
1973 /* Let the debugger run. */
1974 ptrace_stop(exit_code, why, 1, &info);
1975}
1976
1977void ptrace_notify(int exit_code)
1978{
1979 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1980 if (unlikely(current->task_works))
1981 task_work_run();
1982
1983 spin_lock_irq(¤t->sighand->siglock);
1984 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1985 spin_unlock_irq(¤t->sighand->siglock);
1986}
1987
1988/**
1989 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1990 * @signr: signr causing group stop if initiating
1991 *
1992 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1993 * and participate in it. If already set, participate in the existing
1994 * group stop. If participated in a group stop (and thus slept), %true is
1995 * returned with siglock released.
1996 *
1997 * If ptraced, this function doesn't handle stop itself. Instead,
1998 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1999 * untouched. The caller must ensure that INTERRUPT trap handling takes
2000 * places afterwards.
2001 *
2002 * CONTEXT:
2003 * Must be called with @current->sighand->siglock held, which is released
2004 * on %true return.
2005 *
2006 * RETURNS:
2007 * %false if group stop is already cancelled or ptrace trap is scheduled.
2008 * %true if participated in group stop.
2009 */
2010static bool do_signal_stop(int signr)
2011 __releases(¤t->sighand->siglock)
2012{
2013 struct signal_struct *sig = current->signal;
2014
2015 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2016 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2017 struct task_struct *t;
2018
2019 /* signr will be recorded in task->jobctl for retries */
2020 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2021
2022 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2023 unlikely(signal_group_exit(sig)))
2024 return false;
2025 /*
2026 * There is no group stop already in progress. We must
2027 * initiate one now.
2028 *
2029 * While ptraced, a task may be resumed while group stop is
2030 * still in effect and then receive a stop signal and
2031 * initiate another group stop. This deviates from the
2032 * usual behavior as two consecutive stop signals can't
2033 * cause two group stops when !ptraced. That is why we
2034 * also check !task_is_stopped(t) below.
2035 *
2036 * The condition can be distinguished by testing whether
2037 * SIGNAL_STOP_STOPPED is already set. Don't generate
2038 * group_exit_code in such case.
2039 *
2040 * This is not necessary for SIGNAL_STOP_CONTINUED because
2041 * an intervening stop signal is required to cause two
2042 * continued events regardless of ptrace.
2043 */
2044 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2045 sig->group_exit_code = signr;
2046
2047 sig->group_stop_count = 0;
2048
2049 if (task_set_jobctl_pending(current, signr | gstop))
2050 sig->group_stop_count++;
2051
2052 t = current;
2053 while_each_thread(current, t) {
2054 /*
2055 * Setting state to TASK_STOPPED for a group
2056 * stop is always done with the siglock held,
2057 * so this check has no races.
2058 */
2059 if (!task_is_stopped(t) &&
2060 task_set_jobctl_pending(t, signr | gstop)) {
2061 sig->group_stop_count++;
2062 if (likely(!(t->ptrace & PT_SEIZED)))
2063 signal_wake_up(t, 0);
2064 else
2065 ptrace_trap_notify(t);
2066 }
2067 }
2068 }
2069
2070 if (likely(!current->ptrace)) {
2071 int notify = 0;
2072
2073 /*
2074 * If there are no other threads in the group, or if there
2075 * is a group stop in progress and we are the last to stop,
2076 * report to the parent.
2077 */
2078 if (task_participate_group_stop(current))
2079 notify = CLD_STOPPED;
2080
2081 __set_current_state(TASK_STOPPED);
2082 spin_unlock_irq(¤t->sighand->siglock);
2083
2084 /*
2085 * Notify the parent of the group stop completion. Because
2086 * we're not holding either the siglock or tasklist_lock
2087 * here, ptracer may attach inbetween; however, this is for
2088 * group stop and should always be delivered to the real
2089 * parent of the group leader. The new ptracer will get
2090 * its notification when this task transitions into
2091 * TASK_TRACED.
2092 */
2093 if (notify) {
2094 read_lock(&tasklist_lock);
2095 do_notify_parent_cldstop(current, false, notify);
2096 read_unlock(&tasklist_lock);
2097 }
2098
2099 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2100 freezable_schedule();
2101 return true;
2102 } else {
2103 /*
2104 * While ptraced, group stop is handled by STOP trap.
2105 * Schedule it and let the caller deal with it.
2106 */
2107 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2108 return false;
2109 }
2110}
2111
2112/**
2113 * do_jobctl_trap - take care of ptrace jobctl traps
2114 *
2115 * When PT_SEIZED, it's used for both group stop and explicit
2116 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2117 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2118 * the stop signal; otherwise, %SIGTRAP.
2119 *
2120 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2121 * number as exit_code and no siginfo.
2122 *
2123 * CONTEXT:
2124 * Must be called with @current->sighand->siglock held, which may be
2125 * released and re-acquired before returning with intervening sleep.
2126 */
2127static void do_jobctl_trap(void)
2128{
2129 struct signal_struct *signal = current->signal;
2130 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2131
2132 if (current->ptrace & PT_SEIZED) {
2133 if (!signal->group_stop_count &&
2134 !(signal->flags & SIGNAL_STOP_STOPPED))
2135 signr = SIGTRAP;
2136 WARN_ON_ONCE(!signr);
2137 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2138 CLD_STOPPED);
2139 } else {
2140 WARN_ON_ONCE(!signr);
2141 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2142 current->exit_code = 0;
2143 }
2144}
2145
2146static int ptrace_signal(int signr, siginfo_t *info)
2147{
2148 ptrace_signal_deliver();
2149 /*
2150 * We do not check sig_kernel_stop(signr) but set this marker
2151 * unconditionally because we do not know whether debugger will
2152 * change signr. This flag has no meaning unless we are going
2153 * to stop after return from ptrace_stop(). In this case it will
2154 * be checked in do_signal_stop(), we should only stop if it was
2155 * not cleared by SIGCONT while we were sleeping. See also the
2156 * comment in dequeue_signal().
2157 */
2158 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2159 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2160
2161 /* We're back. Did the debugger cancel the sig? */
2162 signr = current->exit_code;
2163 if (signr == 0)
2164 return signr;
2165
2166 current->exit_code = 0;
2167
2168 /*
2169 * Update the siginfo structure if the signal has
2170 * changed. If the debugger wanted something
2171 * specific in the siginfo structure then it should
2172 * have updated *info via PTRACE_SETSIGINFO.
2173 */
2174 if (signr != info->si_signo) {
2175 info->si_signo = signr;
2176 info->si_errno = 0;
2177 info->si_code = SI_USER;
2178 rcu_read_lock();
2179 info->si_pid = task_pid_vnr(current->parent);
2180 info->si_uid = from_kuid_munged(current_user_ns(),
2181 task_uid(current->parent));
2182 rcu_read_unlock();
2183 }
2184
2185 /* If the (new) signal is now blocked, requeue it. */
2186 if (sigismember(¤t->blocked, signr)) {
2187 specific_send_sig_info(signr, info, current);
2188 signr = 0;
2189 }
2190
2191 return signr;
2192}
2193
2194int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2195 struct pt_regs *regs, void *cookie)
2196{
2197 struct sighand_struct *sighand = current->sighand;
2198 struct signal_struct *signal = current->signal;
2199 int signr;
2200
2201 if (unlikely(current->task_works))
2202 task_work_run();
2203
2204 if (unlikely(uprobe_deny_signal()))
2205 return 0;
2206
2207 /*
2208 * Do this once, we can't return to user-mode if freezing() == T.
2209 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2210 * thus do not need another check after return.
2211 */
2212 try_to_freeze();
2213
2214relock:
2215 spin_lock_irq(&sighand->siglock);
2216 /*
2217 * Every stopped thread goes here after wakeup. Check to see if
2218 * we should notify the parent, prepare_signal(SIGCONT) encodes
2219 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2220 */
2221 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2222 int why;
2223
2224 if (signal->flags & SIGNAL_CLD_CONTINUED)
2225 why = CLD_CONTINUED;
2226 else
2227 why = CLD_STOPPED;
2228
2229 signal->flags &= ~SIGNAL_CLD_MASK;
2230
2231 spin_unlock_irq(&sighand->siglock);
2232
2233 /*
2234 * Notify the parent that we're continuing. This event is
2235 * always per-process and doesn't make whole lot of sense
2236 * for ptracers, who shouldn't consume the state via
2237 * wait(2) either, but, for backward compatibility, notify
2238 * the ptracer of the group leader too unless it's gonna be
2239 * a duplicate.
2240 */
2241 read_lock(&tasklist_lock);
2242 do_notify_parent_cldstop(current, false, why);
2243
2244 if (ptrace_reparented(current->group_leader))
2245 do_notify_parent_cldstop(current->group_leader,
2246 true, why);
2247 read_unlock(&tasklist_lock);
2248
2249 goto relock;
2250 }
2251
2252 for (;;) {
2253 struct k_sigaction *ka;
2254
2255 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2256 do_signal_stop(0))
2257 goto relock;
2258
2259 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2260 do_jobctl_trap();
2261 spin_unlock_irq(&sighand->siglock);
2262 goto relock;
2263 }
2264
2265 signr = dequeue_signal(current, ¤t->blocked, info);
2266
2267 if (!signr)
2268 break; /* will return 0 */
2269
2270 if (unlikely(current->ptrace) && signr != SIGKILL) {
2271 signr = ptrace_signal(signr, info);
2272 if (!signr)
2273 continue;
2274 }
2275
2276 ka = &sighand->action[signr-1];
2277
2278 /* Trace actually delivered signals. */
2279 trace_signal_deliver(signr, info, ka);
2280
2281 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2282 continue;
2283 if (ka->sa.sa_handler != SIG_DFL) {
2284 /* Run the handler. */
2285 *return_ka = *ka;
2286
2287 if (ka->sa.sa_flags & SA_ONESHOT)
2288 ka->sa.sa_handler = SIG_DFL;
2289
2290 break; /* will return non-zero "signr" value */
2291 }
2292
2293 /*
2294 * Now we are doing the default action for this signal.
2295 */
2296 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2297 continue;
2298
2299 /*
2300 * Global init gets no signals it doesn't want.
2301 * Container-init gets no signals it doesn't want from same
2302 * container.
2303 *
2304 * Note that if global/container-init sees a sig_kernel_only()
2305 * signal here, the signal must have been generated internally
2306 * or must have come from an ancestor namespace. In either
2307 * case, the signal cannot be dropped.
2308 */
2309 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2310 !sig_kernel_only(signr))
2311 continue;
2312
2313 if (sig_kernel_stop(signr)) {
2314 /*
2315 * The default action is to stop all threads in
2316 * the thread group. The job control signals
2317 * do nothing in an orphaned pgrp, but SIGSTOP
2318 * always works. Note that siglock needs to be
2319 * dropped during the call to is_orphaned_pgrp()
2320 * because of lock ordering with tasklist_lock.
2321 * This allows an intervening SIGCONT to be posted.
2322 * We need to check for that and bail out if necessary.
2323 */
2324 if (signr != SIGSTOP) {
2325 spin_unlock_irq(&sighand->siglock);
2326
2327 /* signals can be posted during this window */
2328
2329 if (is_current_pgrp_orphaned())
2330 goto relock;
2331
2332 spin_lock_irq(&sighand->siglock);
2333 }
2334
2335 if (likely(do_signal_stop(info->si_signo))) {
2336 /* It released the siglock. */
2337 goto relock;
2338 }
2339
2340 /*
2341 * We didn't actually stop, due to a race
2342 * with SIGCONT or something like that.
2343 */
2344 continue;
2345 }
2346
2347 spin_unlock_irq(&sighand->siglock);
2348
2349 /*
2350 * Anything else is fatal, maybe with a core dump.
2351 */
2352 current->flags |= PF_SIGNALED;
2353
2354 if (sig_kernel_coredump(signr)) {
2355 if (print_fatal_signals)
2356 print_fatal_signal(info->si_signo);
2357 proc_coredump_connector(current);
2358 /*
2359 * If it was able to dump core, this kills all
2360 * other threads in the group and synchronizes with
2361 * their demise. If we lost the race with another
2362 * thread getting here, it set group_exit_code
2363 * first and our do_group_exit call below will use
2364 * that value and ignore the one we pass it.
2365 */
2366 do_coredump(info);
2367 }
2368
2369 /*
2370 * Death signals, no core dump.
2371 */
2372 do_group_exit(info->si_signo);
2373 /* NOTREACHED */
2374 }
2375 spin_unlock_irq(&sighand->siglock);
2376 return signr;
2377}
2378
2379/**
2380 * signal_delivered -
2381 * @sig: number of signal being delivered
2382 * @info: siginfo_t of signal being delivered
2383 * @ka: sigaction setting that chose the handler
2384 * @regs: user register state
2385 * @stepping: nonzero if debugger single-step or block-step in use
2386 *
2387 * This function should be called when a signal has successfully been
2388 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2389 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2390 * is set in @ka->sa.sa_flags. Tracing is notified.
2391 */
2392void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2393 struct pt_regs *regs, int stepping)
2394{
2395 sigset_t blocked;
2396
2397 /* A signal was successfully delivered, and the
2398 saved sigmask was stored on the signal frame,
2399 and will be restored by sigreturn. So we can
2400 simply clear the restore sigmask flag. */
2401 clear_restore_sigmask();
2402
2403 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2404 if (!(ka->sa.sa_flags & SA_NODEFER))
2405 sigaddset(&blocked, sig);
2406 set_current_blocked(&blocked);
2407 tracehook_signal_handler(sig, info, ka, regs, stepping);
2408}
2409
2410void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2411{
2412 if (failed)
2413 force_sigsegv(ksig->sig, current);
2414 else
2415 signal_delivered(ksig->sig, &ksig->info, &ksig->ka,
2416 signal_pt_regs(), stepping);
2417}
2418
2419/*
2420 * It could be that complete_signal() picked us to notify about the
2421 * group-wide signal. Other threads should be notified now to take
2422 * the shared signals in @which since we will not.
2423 */
2424static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2425{
2426 sigset_t retarget;
2427 struct task_struct *t;
2428
2429 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2430 if (sigisemptyset(&retarget))
2431 return;
2432
2433 t = tsk;
2434 while_each_thread(tsk, t) {
2435 if (t->flags & PF_EXITING)
2436 continue;
2437
2438 if (!has_pending_signals(&retarget, &t->blocked))
2439 continue;
2440 /* Remove the signals this thread can handle. */
2441 sigandsets(&retarget, &retarget, &t->blocked);
2442
2443 if (!signal_pending(t))
2444 signal_wake_up(t, 0);
2445
2446 if (sigisemptyset(&retarget))
2447 break;
2448 }
2449}
2450
2451void exit_signals(struct task_struct *tsk)
2452{
2453 int group_stop = 0;
2454 sigset_t unblocked;
2455
2456 /*
2457 * @tsk is about to have PF_EXITING set - lock out users which
2458 * expect stable threadgroup.
2459 */
2460 threadgroup_change_begin(tsk);
2461
2462 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2463 tsk->flags |= PF_EXITING;
2464 threadgroup_change_end(tsk);
2465 return;
2466 }
2467
2468 spin_lock_irq(&tsk->sighand->siglock);
2469 /*
2470 * From now this task is not visible for group-wide signals,
2471 * see wants_signal(), do_signal_stop().
2472 */
2473 tsk->flags |= PF_EXITING;
2474
2475 threadgroup_change_end(tsk);
2476
2477 if (!signal_pending(tsk))
2478 goto out;
2479
2480 unblocked = tsk->blocked;
2481 signotset(&unblocked);
2482 retarget_shared_pending(tsk, &unblocked);
2483
2484 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2485 task_participate_group_stop(tsk))
2486 group_stop = CLD_STOPPED;
2487out:
2488 spin_unlock_irq(&tsk->sighand->siglock);
2489
2490 /*
2491 * If group stop has completed, deliver the notification. This
2492 * should always go to the real parent of the group leader.
2493 */
2494 if (unlikely(group_stop)) {
2495 read_lock(&tasklist_lock);
2496 do_notify_parent_cldstop(tsk, false, group_stop);
2497 read_unlock(&tasklist_lock);
2498 }
2499}
2500
2501EXPORT_SYMBOL(recalc_sigpending);
2502EXPORT_SYMBOL_GPL(dequeue_signal);
2503EXPORT_SYMBOL(flush_signals);
2504EXPORT_SYMBOL(force_sig);
2505EXPORT_SYMBOL(send_sig);
2506EXPORT_SYMBOL(send_sig_info);
2507EXPORT_SYMBOL(sigprocmask);
2508EXPORT_SYMBOL(block_all_signals);
2509EXPORT_SYMBOL(unblock_all_signals);
2510
2511
2512/*
2513 * System call entry points.
2514 */
2515
2516/**
2517 * sys_restart_syscall - restart a system call
2518 */
2519SYSCALL_DEFINE0(restart_syscall)
2520{
2521 struct restart_block *restart = ¤t_thread_info()->restart_block;
2522 return restart->fn(restart);
2523}
2524
2525long do_no_restart_syscall(struct restart_block *param)
2526{
2527 return -EINTR;
2528}
2529
2530static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2531{
2532 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2533 sigset_t newblocked;
2534 /* A set of now blocked but previously unblocked signals. */
2535 sigandnsets(&newblocked, newset, ¤t->blocked);
2536 retarget_shared_pending(tsk, &newblocked);
2537 }
2538 tsk->blocked = *newset;
2539 recalc_sigpending();
2540}
2541
2542/**
2543 * set_current_blocked - change current->blocked mask
2544 * @newset: new mask
2545 *
2546 * It is wrong to change ->blocked directly, this helper should be used
2547 * to ensure the process can't miss a shared signal we are going to block.
2548 */
2549void set_current_blocked(sigset_t *newset)
2550{
2551 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2552 __set_current_blocked(newset);
2553}
2554
2555void __set_current_blocked(const sigset_t *newset)
2556{
2557 struct task_struct *tsk = current;
2558
2559 spin_lock_irq(&tsk->sighand->siglock);
2560 __set_task_blocked(tsk, newset);
2561 spin_unlock_irq(&tsk->sighand->siglock);
2562}
2563
2564/*
2565 * This is also useful for kernel threads that want to temporarily
2566 * (or permanently) block certain signals.
2567 *
2568 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2569 * interface happily blocks "unblockable" signals like SIGKILL
2570 * and friends.
2571 */
2572int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2573{
2574 struct task_struct *tsk = current;
2575 sigset_t newset;
2576
2577 /* Lockless, only current can change ->blocked, never from irq */
2578 if (oldset)
2579 *oldset = tsk->blocked;
2580
2581 switch (how) {
2582 case SIG_BLOCK:
2583 sigorsets(&newset, &tsk->blocked, set);
2584 break;
2585 case SIG_UNBLOCK:
2586 sigandnsets(&newset, &tsk->blocked, set);
2587 break;
2588 case SIG_SETMASK:
2589 newset = *set;
2590 break;
2591 default:
2592 return -EINVAL;
2593 }
2594
2595 __set_current_blocked(&newset);
2596 return 0;
2597}
2598
2599/**
2600 * sys_rt_sigprocmask - change the list of currently blocked signals
2601 * @how: whether to add, remove, or set signals
2602 * @nset: stores pending signals
2603 * @oset: previous value of signal mask if non-null
2604 * @sigsetsize: size of sigset_t type
2605 */
2606SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2607 sigset_t __user *, oset, size_t, sigsetsize)
2608{
2609 sigset_t old_set, new_set;
2610 int error;
2611
2612 /* XXX: Don't preclude handling different sized sigset_t's. */
2613 if (sigsetsize != sizeof(sigset_t))
2614 return -EINVAL;
2615
2616 old_set = current->blocked;
2617
2618 if (nset) {
2619 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2620 return -EFAULT;
2621 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2622
2623 error = sigprocmask(how, &new_set, NULL);
2624 if (error)
2625 return error;
2626 }
2627
2628 if (oset) {
2629 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2630 return -EFAULT;
2631 }
2632
2633 return 0;
2634}
2635
2636#ifdef CONFIG_COMPAT
2637COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2638 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2639{
2640#ifdef __BIG_ENDIAN
2641 sigset_t old_set = current->blocked;
2642
2643 /* XXX: Don't preclude handling different sized sigset_t's. */
2644 if (sigsetsize != sizeof(sigset_t))
2645 return -EINVAL;
2646
2647 if (nset) {
2648 compat_sigset_t new32;
2649 sigset_t new_set;
2650 int error;
2651 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2652 return -EFAULT;
2653
2654 sigset_from_compat(&new_set, &new32);
2655 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2656
2657 error = sigprocmask(how, &new_set, NULL);
2658 if (error)
2659 return error;
2660 }
2661 if (oset) {
2662 compat_sigset_t old32;
2663 sigset_to_compat(&old32, &old_set);
2664 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2665 return -EFAULT;
2666 }
2667 return 0;
2668#else
2669 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2670 (sigset_t __user *)oset, sigsetsize);
2671#endif
2672}
2673#endif
2674
2675static int do_sigpending(void *set, unsigned long sigsetsize)
2676{
2677 if (sigsetsize > sizeof(sigset_t))
2678 return -EINVAL;
2679
2680 spin_lock_irq(¤t->sighand->siglock);
2681 sigorsets(set, ¤t->pending.signal,
2682 ¤t->signal->shared_pending.signal);
2683 spin_unlock_irq(¤t->sighand->siglock);
2684
2685 /* Outside the lock because only this thread touches it. */
2686 sigandsets(set, ¤t->blocked, set);
2687 return 0;
2688}
2689
2690/**
2691 * sys_rt_sigpending - examine a pending signal that has been raised
2692 * while blocked
2693 * @uset: stores pending signals
2694 * @sigsetsize: size of sigset_t type or larger
2695 */
2696SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2697{
2698 sigset_t set;
2699 int err = do_sigpending(&set, sigsetsize);
2700 if (!err && copy_to_user(uset, &set, sigsetsize))
2701 err = -EFAULT;
2702 return err;
2703}
2704
2705#ifdef CONFIG_COMPAT
2706COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2707 compat_size_t, sigsetsize)
2708{
2709#ifdef __BIG_ENDIAN
2710 sigset_t set;
2711 int err = do_sigpending(&set, sigsetsize);
2712 if (!err) {
2713 compat_sigset_t set32;
2714 sigset_to_compat(&set32, &set);
2715 /* we can get here only if sigsetsize <= sizeof(set) */
2716 if (copy_to_user(uset, &set32, sigsetsize))
2717 err = -EFAULT;
2718 }
2719 return err;
2720#else
2721 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2722#endif
2723}
2724#endif
2725
2726#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2727
2728int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2729{
2730 int err;
2731
2732 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2733 return -EFAULT;
2734 if (from->si_code < 0)
2735 return __copy_to_user(to, from, sizeof(siginfo_t))
2736 ? -EFAULT : 0;
2737 /*
2738 * If you change siginfo_t structure, please be sure
2739 * this code is fixed accordingly.
2740 * Please remember to update the signalfd_copyinfo() function
2741 * inside fs/signalfd.c too, in case siginfo_t changes.
2742 * It should never copy any pad contained in the structure
2743 * to avoid security leaks, but must copy the generic
2744 * 3 ints plus the relevant union member.
2745 */
2746 err = __put_user(from->si_signo, &to->si_signo);
2747 err |= __put_user(from->si_errno, &to->si_errno);
2748 err |= __put_user((short)from->si_code, &to->si_code);
2749 switch (from->si_code & __SI_MASK) {
2750 case __SI_KILL:
2751 err |= __put_user(from->si_pid, &to->si_pid);
2752 err |= __put_user(from->si_uid, &to->si_uid);
2753 break;
2754 case __SI_TIMER:
2755 err |= __put_user(from->si_tid, &to->si_tid);
2756 err |= __put_user(from->si_overrun, &to->si_overrun);
2757 err |= __put_user(from->si_ptr, &to->si_ptr);
2758 break;
2759 case __SI_POLL:
2760 err |= __put_user(from->si_band, &to->si_band);
2761 err |= __put_user(from->si_fd, &to->si_fd);
2762 break;
2763 case __SI_FAULT:
2764 err |= __put_user(from->si_addr, &to->si_addr);
2765#ifdef __ARCH_SI_TRAPNO
2766 err |= __put_user(from->si_trapno, &to->si_trapno);
2767#endif
2768#ifdef BUS_MCEERR_AO
2769 /*
2770 * Other callers might not initialize the si_lsb field,
2771 * so check explicitly for the right codes here.
2772 */
2773 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2774 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2775#endif
2776 break;
2777 case __SI_CHLD:
2778 err |= __put_user(from->si_pid, &to->si_pid);
2779 err |= __put_user(from->si_uid, &to->si_uid);
2780 err |= __put_user(from->si_status, &to->si_status);
2781 err |= __put_user(from->si_utime, &to->si_utime);
2782 err |= __put_user(from->si_stime, &to->si_stime);
2783 break;
2784 case __SI_RT: /* This is not generated by the kernel as of now. */
2785 case __SI_MESGQ: /* But this is */
2786 err |= __put_user(from->si_pid, &to->si_pid);
2787 err |= __put_user(from->si_uid, &to->si_uid);
2788 err |= __put_user(from->si_ptr, &to->si_ptr);
2789 break;
2790#ifdef __ARCH_SIGSYS
2791 case __SI_SYS:
2792 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2793 err |= __put_user(from->si_syscall, &to->si_syscall);
2794 err |= __put_user(from->si_arch, &to->si_arch);
2795 break;
2796#endif
2797 default: /* this is just in case for now ... */
2798 err |= __put_user(from->si_pid, &to->si_pid);
2799 err |= __put_user(from->si_uid, &to->si_uid);
2800 break;
2801 }
2802 return err;
2803}
2804
2805#endif
2806
2807/**
2808 * do_sigtimedwait - wait for queued signals specified in @which
2809 * @which: queued signals to wait for
2810 * @info: if non-null, the signal's siginfo is returned here
2811 * @ts: upper bound on process time suspension
2812 */
2813int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2814 const struct timespec *ts)
2815{
2816 struct task_struct *tsk = current;
2817 long timeout = MAX_SCHEDULE_TIMEOUT;
2818 sigset_t mask = *which;
2819 int sig;
2820
2821 if (ts) {
2822 if (!timespec_valid(ts))
2823 return -EINVAL;
2824 timeout = timespec_to_jiffies(ts);
2825 /*
2826 * We can be close to the next tick, add another one
2827 * to ensure we will wait at least the time asked for.
2828 */
2829 if (ts->tv_sec || ts->tv_nsec)
2830 timeout++;
2831 }
2832
2833 /*
2834 * Invert the set of allowed signals to get those we want to block.
2835 */
2836 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2837 signotset(&mask);
2838
2839 spin_lock_irq(&tsk->sighand->siglock);
2840 sig = dequeue_signal(tsk, &mask, info);
2841 if (!sig && timeout) {
2842 /*
2843 * None ready, temporarily unblock those we're interested
2844 * while we are sleeping in so that we'll be awakened when
2845 * they arrive. Unblocking is always fine, we can avoid
2846 * set_current_blocked().
2847 */
2848 tsk->real_blocked = tsk->blocked;
2849 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2850 recalc_sigpending();
2851 spin_unlock_irq(&tsk->sighand->siglock);
2852
2853 timeout = freezable_schedule_timeout_interruptible(timeout);
2854
2855 spin_lock_irq(&tsk->sighand->siglock);
2856 __set_task_blocked(tsk, &tsk->real_blocked);
2857 siginitset(&tsk->real_blocked, 0);
2858 sig = dequeue_signal(tsk, &mask, info);
2859 }
2860 spin_unlock_irq(&tsk->sighand->siglock);
2861
2862 if (sig)
2863 return sig;
2864 return timeout ? -EINTR : -EAGAIN;
2865}
2866
2867/**
2868 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2869 * in @uthese
2870 * @uthese: queued signals to wait for
2871 * @uinfo: if non-null, the signal's siginfo is returned here
2872 * @uts: upper bound on process time suspension
2873 * @sigsetsize: size of sigset_t type
2874 */
2875SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2876 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2877 size_t, sigsetsize)
2878{
2879 sigset_t these;
2880 struct timespec ts;
2881 siginfo_t info;
2882 int ret;
2883
2884 /* XXX: Don't preclude handling different sized sigset_t's. */
2885 if (sigsetsize != sizeof(sigset_t))
2886 return -EINVAL;
2887
2888 if (copy_from_user(&these, uthese, sizeof(these)))
2889 return -EFAULT;
2890
2891 if (uts) {
2892 if (copy_from_user(&ts, uts, sizeof(ts)))
2893 return -EFAULT;
2894 }
2895
2896 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2897
2898 if (ret > 0 && uinfo) {
2899 if (copy_siginfo_to_user(uinfo, &info))
2900 ret = -EFAULT;
2901 }
2902
2903 return ret;
2904}
2905
2906/**
2907 * sys_kill - send a signal to a process
2908 * @pid: the PID of the process
2909 * @sig: signal to be sent
2910 */
2911SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2912{
2913 struct siginfo info;
2914
2915 info.si_signo = sig;
2916 info.si_errno = 0;
2917 info.si_code = SI_USER;
2918 info.si_pid = task_tgid_vnr(current);
2919 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2920
2921 return kill_something_info(sig, &info, pid);
2922}
2923
2924static int
2925do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2926{
2927 struct task_struct *p;
2928 int error = -ESRCH;
2929
2930 rcu_read_lock();
2931 p = find_task_by_vpid(pid);
2932 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2933 error = check_kill_permission(sig, info, p);
2934 /*
2935 * The null signal is a permissions and process existence
2936 * probe. No signal is actually delivered.
2937 */
2938 if (!error && sig) {
2939 error = do_send_sig_info(sig, info, p, false);
2940 /*
2941 * If lock_task_sighand() failed we pretend the task
2942 * dies after receiving the signal. The window is tiny,
2943 * and the signal is private anyway.
2944 */
2945 if (unlikely(error == -ESRCH))
2946 error = 0;
2947 }
2948 }
2949 rcu_read_unlock();
2950
2951 return error;
2952}
2953
2954static int do_tkill(pid_t tgid, pid_t pid, int sig)
2955{
2956 struct siginfo info = {};
2957
2958 info.si_signo = sig;
2959 info.si_errno = 0;
2960 info.si_code = SI_TKILL;
2961 info.si_pid = task_tgid_vnr(current);
2962 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2963
2964 return do_send_specific(tgid, pid, sig, &info);
2965}
2966
2967/**
2968 * sys_tgkill - send signal to one specific thread
2969 * @tgid: the thread group ID of the thread
2970 * @pid: the PID of the thread
2971 * @sig: signal to be sent
2972 *
2973 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2974 * exists but it's not belonging to the target process anymore. This
2975 * method solves the problem of threads exiting and PIDs getting reused.
2976 */
2977SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2978{
2979 /* This is only valid for single tasks */
2980 if (pid <= 0 || tgid <= 0)
2981 return -EINVAL;
2982
2983 return do_tkill(tgid, pid, sig);
2984}
2985
2986/**
2987 * sys_tkill - send signal to one specific task
2988 * @pid: the PID of the task
2989 * @sig: signal to be sent
2990 *
2991 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2992 */
2993SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2994{
2995 /* This is only valid for single tasks */
2996 if (pid <= 0)
2997 return -EINVAL;
2998
2999 return do_tkill(0, pid, sig);
3000}
3001
3002static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3003{
3004 /* Not even root can pretend to send signals from the kernel.
3005 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3006 */
3007 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3008 (task_pid_vnr(current) != pid)) {
3009 /* We used to allow any < 0 si_code */
3010 WARN_ON_ONCE(info->si_code < 0);
3011 return -EPERM;
3012 }
3013 info->si_signo = sig;
3014
3015 /* POSIX.1b doesn't mention process groups. */
3016 return kill_proc_info(sig, info, pid);
3017}
3018
3019/**
3020 * sys_rt_sigqueueinfo - send signal information to a signal
3021 * @pid: the PID of the thread
3022 * @sig: signal to be sent
3023 * @uinfo: signal info to be sent
3024 */
3025SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3026 siginfo_t __user *, uinfo)
3027{
3028 siginfo_t info;
3029 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3030 return -EFAULT;
3031 return do_rt_sigqueueinfo(pid, sig, &info);
3032}
3033
3034#ifdef CONFIG_COMPAT
3035COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3036 compat_pid_t, pid,
3037 int, sig,
3038 struct compat_siginfo __user *, uinfo)
3039{
3040 siginfo_t info;
3041 int ret = copy_siginfo_from_user32(&info, uinfo);
3042 if (unlikely(ret))
3043 return ret;
3044 return do_rt_sigqueueinfo(pid, sig, &info);
3045}
3046#endif
3047
3048static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3049{
3050 /* This is only valid for single tasks */
3051 if (pid <= 0 || tgid <= 0)
3052 return -EINVAL;
3053
3054 /* Not even root can pretend to send signals from the kernel.
3055 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3056 */
3057 if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
3058 (task_pid_vnr(current) != pid)) {
3059 /* We used to allow any < 0 si_code */
3060 WARN_ON_ONCE(info->si_code < 0);
3061 return -EPERM;
3062 }
3063 info->si_signo = sig;
3064
3065 return do_send_specific(tgid, pid, sig, info);
3066}
3067
3068SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3069 siginfo_t __user *, uinfo)
3070{
3071 siginfo_t info;
3072
3073 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3074 return -EFAULT;
3075
3076 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3077}
3078
3079#ifdef CONFIG_COMPAT
3080COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3081 compat_pid_t, tgid,
3082 compat_pid_t, pid,
3083 int, sig,
3084 struct compat_siginfo __user *, uinfo)
3085{
3086 siginfo_t info;
3087
3088 if (copy_siginfo_from_user32(&info, uinfo))
3089 return -EFAULT;
3090 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3091}
3092#endif
3093
3094int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3095{
3096 struct task_struct *t = current;
3097 struct k_sigaction *k;
3098 sigset_t mask;
3099
3100 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3101 return -EINVAL;
3102
3103 k = &t->sighand->action[sig-1];
3104
3105 spin_lock_irq(¤t->sighand->siglock);
3106 if (oact)
3107 *oact = *k;
3108
3109 if (act) {
3110 sigdelsetmask(&act->sa.sa_mask,
3111 sigmask(SIGKILL) | sigmask(SIGSTOP));
3112 *k = *act;
3113 /*
3114 * POSIX 3.3.1.3:
3115 * "Setting a signal action to SIG_IGN for a signal that is
3116 * pending shall cause the pending signal to be discarded,
3117 * whether or not it is blocked."
3118 *
3119 * "Setting a signal action to SIG_DFL for a signal that is
3120 * pending and whose default action is to ignore the signal
3121 * (for example, SIGCHLD), shall cause the pending signal to
3122 * be discarded, whether or not it is blocked"
3123 */
3124 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3125 sigemptyset(&mask);
3126 sigaddset(&mask, sig);
3127 rm_from_queue_full(&mask, &t->signal->shared_pending);
3128 do {
3129 rm_from_queue_full(&mask, &t->pending);
3130 } while_each_thread(current, t);
3131 }
3132 }
3133
3134 spin_unlock_irq(¤t->sighand->siglock);
3135 return 0;
3136}
3137
3138static int
3139do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3140{
3141 stack_t oss;
3142 int error;
3143
3144 oss.ss_sp = (void __user *) current->sas_ss_sp;
3145 oss.ss_size = current->sas_ss_size;
3146 oss.ss_flags = sas_ss_flags(sp);
3147
3148 if (uss) {
3149 void __user *ss_sp;
3150 size_t ss_size;
3151 int ss_flags;
3152
3153 error = -EFAULT;
3154 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3155 goto out;
3156 error = __get_user(ss_sp, &uss->ss_sp) |
3157 __get_user(ss_flags, &uss->ss_flags) |
3158 __get_user(ss_size, &uss->ss_size);
3159 if (error)
3160 goto out;
3161
3162 error = -EPERM;
3163 if (on_sig_stack(sp))
3164 goto out;
3165
3166 error = -EINVAL;
3167 /*
3168 * Note - this code used to test ss_flags incorrectly:
3169 * old code may have been written using ss_flags==0
3170 * to mean ss_flags==SS_ONSTACK (as this was the only
3171 * way that worked) - this fix preserves that older
3172 * mechanism.
3173 */
3174 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3175 goto out;
3176
3177 if (ss_flags == SS_DISABLE) {
3178 ss_size = 0;
3179 ss_sp = NULL;
3180 } else {
3181 error = -ENOMEM;
3182 if (ss_size < MINSIGSTKSZ)
3183 goto out;
3184 }
3185
3186 current->sas_ss_sp = (unsigned long) ss_sp;
3187 current->sas_ss_size = ss_size;
3188 }
3189
3190 error = 0;
3191 if (uoss) {
3192 error = -EFAULT;
3193 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3194 goto out;
3195 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3196 __put_user(oss.ss_size, &uoss->ss_size) |
3197 __put_user(oss.ss_flags, &uoss->ss_flags);
3198 }
3199
3200out:
3201 return error;
3202}
3203SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3204{
3205 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3206}
3207
3208int restore_altstack(const stack_t __user *uss)
3209{
3210 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3211 /* squash all but EFAULT for now */
3212 return err == -EFAULT ? err : 0;
3213}
3214
3215int __save_altstack(stack_t __user *uss, unsigned long sp)
3216{
3217 struct task_struct *t = current;
3218 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3219 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3220 __put_user(t->sas_ss_size, &uss->ss_size);
3221}
3222
3223#ifdef CONFIG_COMPAT
3224COMPAT_SYSCALL_DEFINE2(sigaltstack,
3225 const compat_stack_t __user *, uss_ptr,
3226 compat_stack_t __user *, uoss_ptr)
3227{
3228 stack_t uss, uoss;
3229 int ret;
3230 mm_segment_t seg;
3231
3232 if (uss_ptr) {
3233 compat_stack_t uss32;
3234
3235 memset(&uss, 0, sizeof(stack_t));
3236 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3237 return -EFAULT;
3238 uss.ss_sp = compat_ptr(uss32.ss_sp);
3239 uss.ss_flags = uss32.ss_flags;
3240 uss.ss_size = uss32.ss_size;
3241 }
3242 seg = get_fs();
3243 set_fs(KERNEL_DS);
3244 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3245 (stack_t __force __user *) &uoss,
3246 compat_user_stack_pointer());
3247 set_fs(seg);
3248 if (ret >= 0 && uoss_ptr) {
3249 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3250 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3251 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3252 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3253 ret = -EFAULT;
3254 }
3255 return ret;
3256}
3257
3258int compat_restore_altstack(const compat_stack_t __user *uss)
3259{
3260 int err = compat_sys_sigaltstack(uss, NULL);
3261 /* squash all but -EFAULT for now */
3262 return err == -EFAULT ? err : 0;
3263}
3264
3265int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3266{
3267 struct task_struct *t = current;
3268 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3269 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3270 __put_user(t->sas_ss_size, &uss->ss_size);
3271}
3272#endif
3273
3274#ifdef __ARCH_WANT_SYS_SIGPENDING
3275
3276/**
3277 * sys_sigpending - examine pending signals
3278 * @set: where mask of pending signal is returned
3279 */
3280SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3281{
3282 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3283}
3284
3285#endif
3286
3287#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3288/**
3289 * sys_sigprocmask - examine and change blocked signals
3290 * @how: whether to add, remove, or set signals
3291 * @nset: signals to add or remove (if non-null)
3292 * @oset: previous value of signal mask if non-null
3293 *
3294 * Some platforms have their own version with special arguments;
3295 * others support only sys_rt_sigprocmask.
3296 */
3297
3298SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3299 old_sigset_t __user *, oset)
3300{
3301 old_sigset_t old_set, new_set;
3302 sigset_t new_blocked;
3303
3304 old_set = current->blocked.sig[0];
3305
3306 if (nset) {
3307 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3308 return -EFAULT;
3309
3310 new_blocked = current->blocked;
3311
3312 switch (how) {
3313 case SIG_BLOCK:
3314 sigaddsetmask(&new_blocked, new_set);
3315 break;
3316 case SIG_UNBLOCK:
3317 sigdelsetmask(&new_blocked, new_set);
3318 break;
3319 case SIG_SETMASK:
3320 new_blocked.sig[0] = new_set;
3321 break;
3322 default:
3323 return -EINVAL;
3324 }
3325
3326 set_current_blocked(&new_blocked);
3327 }
3328
3329 if (oset) {
3330 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3331 return -EFAULT;
3332 }
3333
3334 return 0;
3335}
3336#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3337
3338#ifndef CONFIG_ODD_RT_SIGACTION
3339/**
3340 * sys_rt_sigaction - alter an action taken by a process
3341 * @sig: signal to be sent
3342 * @act: new sigaction
3343 * @oact: used to save the previous sigaction
3344 * @sigsetsize: size of sigset_t type
3345 */
3346SYSCALL_DEFINE4(rt_sigaction, int, sig,
3347 const struct sigaction __user *, act,
3348 struct sigaction __user *, oact,
3349 size_t, sigsetsize)
3350{
3351 struct k_sigaction new_sa, old_sa;
3352 int ret = -EINVAL;
3353
3354 /* XXX: Don't preclude handling different sized sigset_t's. */
3355 if (sigsetsize != sizeof(sigset_t))
3356 goto out;
3357
3358 if (act) {
3359 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3360 return -EFAULT;
3361 }
3362
3363 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3364
3365 if (!ret && oact) {
3366 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3367 return -EFAULT;
3368 }
3369out:
3370 return ret;
3371}
3372#ifdef CONFIG_COMPAT
3373COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3374 const struct compat_sigaction __user *, act,
3375 struct compat_sigaction __user *, oact,
3376 compat_size_t, sigsetsize)
3377{
3378 struct k_sigaction new_ka, old_ka;
3379 compat_sigset_t mask;
3380#ifdef __ARCH_HAS_SA_RESTORER
3381 compat_uptr_t restorer;
3382#endif
3383 int ret;
3384
3385 /* XXX: Don't preclude handling different sized sigset_t's. */
3386 if (sigsetsize != sizeof(compat_sigset_t))
3387 return -EINVAL;
3388
3389 if (act) {
3390 compat_uptr_t handler;
3391 ret = get_user(handler, &act->sa_handler);
3392 new_ka.sa.sa_handler = compat_ptr(handler);
3393#ifdef __ARCH_HAS_SA_RESTORER
3394 ret |= get_user(restorer, &act->sa_restorer);
3395 new_ka.sa.sa_restorer = compat_ptr(restorer);
3396#endif
3397 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3398 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3399 if (ret)
3400 return -EFAULT;
3401 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3402 }
3403
3404 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3405 if (!ret && oact) {
3406 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3407 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3408 &oact->sa_handler);
3409 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3410 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3411#ifdef __ARCH_HAS_SA_RESTORER
3412 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3413 &oact->sa_restorer);
3414#endif
3415 }
3416 return ret;
3417}
3418#endif
3419#endif /* !CONFIG_ODD_RT_SIGACTION */
3420
3421#ifdef CONFIG_OLD_SIGACTION
3422SYSCALL_DEFINE3(sigaction, int, sig,
3423 const struct old_sigaction __user *, act,
3424 struct old_sigaction __user *, oact)
3425{
3426 struct k_sigaction new_ka, old_ka;
3427 int ret;
3428
3429 if (act) {
3430 old_sigset_t mask;
3431 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3432 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3433 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3434 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3435 __get_user(mask, &act->sa_mask))
3436 return -EFAULT;
3437#ifdef __ARCH_HAS_KA_RESTORER
3438 new_ka.ka_restorer = NULL;
3439#endif
3440 siginitset(&new_ka.sa.sa_mask, mask);
3441 }
3442
3443 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3444
3445 if (!ret && oact) {
3446 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3447 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3448 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3449 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3450 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3451 return -EFAULT;
3452 }
3453
3454 return ret;
3455}
3456#endif
3457#ifdef CONFIG_COMPAT_OLD_SIGACTION
3458COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3459 const struct compat_old_sigaction __user *, act,
3460 struct compat_old_sigaction __user *, oact)
3461{
3462 struct k_sigaction new_ka, old_ka;
3463 int ret;
3464 compat_old_sigset_t mask;
3465 compat_uptr_t handler, restorer;
3466
3467 if (act) {
3468 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3469 __get_user(handler, &act->sa_handler) ||
3470 __get_user(restorer, &act->sa_restorer) ||
3471 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3472 __get_user(mask, &act->sa_mask))
3473 return -EFAULT;
3474
3475#ifdef __ARCH_HAS_KA_RESTORER
3476 new_ka.ka_restorer = NULL;
3477#endif
3478 new_ka.sa.sa_handler = compat_ptr(handler);
3479 new_ka.sa.sa_restorer = compat_ptr(restorer);
3480 siginitset(&new_ka.sa.sa_mask, mask);
3481 }
3482
3483 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3484
3485 if (!ret && oact) {
3486 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3487 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3488 &oact->sa_handler) ||
3489 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3490 &oact->sa_restorer) ||
3491 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3492 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3493 return -EFAULT;
3494 }
3495 return ret;
3496}
3497#endif
3498
3499#ifdef __ARCH_WANT_SYS_SGETMASK
3500
3501/*
3502 * For backwards compatibility. Functionality superseded by sigprocmask.
3503 */
3504SYSCALL_DEFINE0(sgetmask)
3505{
3506 /* SMP safe */
3507 return current->blocked.sig[0];
3508}
3509
3510SYSCALL_DEFINE1(ssetmask, int, newmask)
3511{
3512 int old = current->blocked.sig[0];
3513 sigset_t newset;
3514
3515 siginitset(&newset, newmask);
3516 set_current_blocked(&newset);
3517
3518 return old;
3519}
3520#endif /* __ARCH_WANT_SGETMASK */
3521
3522#ifdef __ARCH_WANT_SYS_SIGNAL
3523/*
3524 * For backwards compatibility. Functionality superseded by sigaction.
3525 */
3526SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3527{
3528 struct k_sigaction new_sa, old_sa;
3529 int ret;
3530
3531 new_sa.sa.sa_handler = handler;
3532 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3533 sigemptyset(&new_sa.sa.sa_mask);
3534
3535 ret = do_sigaction(sig, &new_sa, &old_sa);
3536
3537 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3538}
3539#endif /* __ARCH_WANT_SYS_SIGNAL */
3540
3541#ifdef __ARCH_WANT_SYS_PAUSE
3542
3543SYSCALL_DEFINE0(pause)
3544{
3545 while (!signal_pending(current)) {
3546 current->state = TASK_INTERRUPTIBLE;
3547 schedule();
3548 }
3549 return -ERESTARTNOHAND;
3550}
3551
3552#endif
3553
3554int sigsuspend(sigset_t *set)
3555{
3556 current->saved_sigmask = current->blocked;
3557 set_current_blocked(set);
3558
3559 current->state = TASK_INTERRUPTIBLE;
3560 schedule();
3561 set_restore_sigmask();
3562 return -ERESTARTNOHAND;
3563}
3564
3565/**
3566 * sys_rt_sigsuspend - replace the signal mask for a value with the
3567 * @unewset value until a signal is received
3568 * @unewset: new signal mask value
3569 * @sigsetsize: size of sigset_t type
3570 */
3571SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3572{
3573 sigset_t newset;
3574
3575 /* XXX: Don't preclude handling different sized sigset_t's. */
3576 if (sigsetsize != sizeof(sigset_t))
3577 return -EINVAL;
3578
3579 if (copy_from_user(&newset, unewset, sizeof(newset)))
3580 return -EFAULT;
3581 return sigsuspend(&newset);
3582}
3583
3584#ifdef CONFIG_COMPAT
3585COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3586{
3587#ifdef __BIG_ENDIAN
3588 sigset_t newset;
3589 compat_sigset_t newset32;
3590
3591 /* XXX: Don't preclude handling different sized sigset_t's. */
3592 if (sigsetsize != sizeof(sigset_t))
3593 return -EINVAL;
3594
3595 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3596 return -EFAULT;
3597 sigset_from_compat(&newset, &newset32);
3598 return sigsuspend(&newset);
3599#else
3600 /* on little-endian bitmaps don't care about granularity */
3601 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3602#endif
3603}
3604#endif
3605
3606#ifdef CONFIG_OLD_SIGSUSPEND
3607SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3608{
3609 sigset_t blocked;
3610 siginitset(&blocked, mask);
3611 return sigsuspend(&blocked);
3612}
3613#endif
3614#ifdef CONFIG_OLD_SIGSUSPEND3
3615SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3616{
3617 sigset_t blocked;
3618 siginitset(&blocked, mask);
3619 return sigsuspend(&blocked);
3620}
3621#endif
3622
3623__weak const char *arch_vma_name(struct vm_area_struct *vma)
3624{
3625 return NULL;
3626}
3627
3628void __init signals_init(void)
3629{
3630 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3631}
3632
3633#ifdef CONFIG_KGDB_KDB
3634#include <linux/kdb.h>
3635/*
3636 * kdb_send_sig_info - Allows kdb to send signals without exposing
3637 * signal internals. This function checks if the required locks are
3638 * available before calling the main signal code, to avoid kdb
3639 * deadlocks.
3640 */
3641void
3642kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3643{
3644 static struct task_struct *kdb_prev_t;
3645 int sig, new_t;
3646 if (!spin_trylock(&t->sighand->siglock)) {
3647 kdb_printf("Can't do kill command now.\n"
3648 "The sigmask lock is held somewhere else in "
3649 "kernel, try again later\n");
3650 return;
3651 }
3652 spin_unlock(&t->sighand->siglock);
3653 new_t = kdb_prev_t != t;
3654 kdb_prev_t = t;
3655 if (t->state != TASK_RUNNING && new_t) {
3656 kdb_printf("Process is not RUNNING, sending a signal from "
3657 "kdb risks deadlock\n"
3658 "on the run queue locks. "
3659 "The signal has _not_ been sent.\n"
3660 "Reissue the kill command if you want to risk "
3661 "the deadlock.\n");
3662 return;
3663 }
3664 sig = info->si_signo;
3665 if (send_sig_info(sig, info, t))
3666 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3667 sig, t->pid);
3668 else
3669 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3670}
3671#endif /* CONFIG_KGDB_KDB */
1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/security.h>
21#include <linux/syscalls.h>
22#include <linux/ptrace.h>
23#include <linux/signal.h>
24#include <linux/signalfd.h>
25#include <linux/ratelimit.h>
26#include <linux/tracehook.h>
27#include <linux/capability.h>
28#include <linux/freezer.h>
29#include <linux/pid_namespace.h>
30#include <linux/nsproxy.h>
31#define CREATE_TRACE_POINTS
32#include <trace/events/signal.h>
33
34#include <asm/param.h>
35#include <asm/uaccess.h>
36#include <asm/unistd.h>
37#include <asm/siginfo.h>
38#include "audit.h" /* audit_signal_info() */
39
40/*
41 * SLAB caches for signal bits.
42 */
43
44static struct kmem_cache *sigqueue_cachep;
45
46int print_fatal_signals __read_mostly;
47
48static void __user *sig_handler(struct task_struct *t, int sig)
49{
50 return t->sighand->action[sig - 1].sa.sa_handler;
51}
52
53static int sig_handler_ignored(void __user *handler, int sig)
54{
55 /* Is it explicitly or implicitly ignored? */
56 return handler == SIG_IGN ||
57 (handler == SIG_DFL && sig_kernel_ignore(sig));
58}
59
60static int sig_task_ignored(struct task_struct *t, int sig,
61 int from_ancestor_ns)
62{
63 void __user *handler;
64
65 handler = sig_handler(t, sig);
66
67 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
68 handler == SIG_DFL && !from_ancestor_ns)
69 return 1;
70
71 return sig_handler_ignored(handler, sig);
72}
73
74static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
75{
76 /*
77 * Blocked signals are never ignored, since the
78 * signal handler may change by the time it is
79 * unblocked.
80 */
81 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
82 return 0;
83
84 if (!sig_task_ignored(t, sig, from_ancestor_ns))
85 return 0;
86
87 /*
88 * Tracers may want to know about even ignored signals.
89 */
90 return !t->ptrace;
91}
92
93/*
94 * Re-calculate pending state from the set of locally pending
95 * signals, globally pending signals, and blocked signals.
96 */
97static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
98{
99 unsigned long ready;
100 long i;
101
102 switch (_NSIG_WORDS) {
103 default:
104 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
105 ready |= signal->sig[i] &~ blocked->sig[i];
106 break;
107
108 case 4: ready = signal->sig[3] &~ blocked->sig[3];
109 ready |= signal->sig[2] &~ blocked->sig[2];
110 ready |= signal->sig[1] &~ blocked->sig[1];
111 ready |= signal->sig[0] &~ blocked->sig[0];
112 break;
113
114 case 2: ready = signal->sig[1] &~ blocked->sig[1];
115 ready |= signal->sig[0] &~ blocked->sig[0];
116 break;
117
118 case 1: ready = signal->sig[0] &~ blocked->sig[0];
119 }
120 return ready != 0;
121}
122
123#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
124
125static int recalc_sigpending_tsk(struct task_struct *t)
126{
127 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
128 PENDING(&t->pending, &t->blocked) ||
129 PENDING(&t->signal->shared_pending, &t->blocked)) {
130 set_tsk_thread_flag(t, TIF_SIGPENDING);
131 return 1;
132 }
133 /*
134 * We must never clear the flag in another thread, or in current
135 * when it's possible the current syscall is returning -ERESTART*.
136 * So we don't clear it here, and only callers who know they should do.
137 */
138 return 0;
139}
140
141/*
142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
143 * This is superfluous when called on current, the wakeup is a harmless no-op.
144 */
145void recalc_sigpending_and_wake(struct task_struct *t)
146{
147 if (recalc_sigpending_tsk(t))
148 signal_wake_up(t, 0);
149}
150
151void recalc_sigpending(void)
152{
153 if (!recalc_sigpending_tsk(current) && !freezing(current))
154 clear_thread_flag(TIF_SIGPENDING);
155
156}
157
158/* Given the mask, find the first available signal that should be serviced. */
159
160#define SYNCHRONOUS_MASK \
161 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
162 sigmask(SIGTRAP) | sigmask(SIGFPE))
163
164int next_signal(struct sigpending *pending, sigset_t *mask)
165{
166 unsigned long i, *s, *m, x;
167 int sig = 0;
168
169 s = pending->signal.sig;
170 m = mask->sig;
171
172 /*
173 * Handle the first word specially: it contains the
174 * synchronous signals that need to be dequeued first.
175 */
176 x = *s &~ *m;
177 if (x) {
178 if (x & SYNCHRONOUS_MASK)
179 x &= SYNCHRONOUS_MASK;
180 sig = ffz(~x) + 1;
181 return sig;
182 }
183
184 switch (_NSIG_WORDS) {
185 default:
186 for (i = 1; i < _NSIG_WORDS; ++i) {
187 x = *++s &~ *++m;
188 if (!x)
189 continue;
190 sig = ffz(~x) + i*_NSIG_BPW + 1;
191 break;
192 }
193 break;
194
195 case 2:
196 x = s[1] &~ m[1];
197 if (!x)
198 break;
199 sig = ffz(~x) + _NSIG_BPW + 1;
200 break;
201
202 case 1:
203 /* Nothing to do */
204 break;
205 }
206
207 return sig;
208}
209
210static inline void print_dropped_signal(int sig)
211{
212 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
213
214 if (!print_fatal_signals)
215 return;
216
217 if (!__ratelimit(&ratelimit_state))
218 return;
219
220 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
221 current->comm, current->pid, sig);
222}
223
224/**
225 * task_set_jobctl_pending - set jobctl pending bits
226 * @task: target task
227 * @mask: pending bits to set
228 *
229 * Clear @mask from @task->jobctl. @mask must be subset of
230 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
231 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
232 * cleared. If @task is already being killed or exiting, this function
233 * becomes noop.
234 *
235 * CONTEXT:
236 * Must be called with @task->sighand->siglock held.
237 *
238 * RETURNS:
239 * %true if @mask is set, %false if made noop because @task was dying.
240 */
241bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
242{
243 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
244 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
245 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
246
247 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
248 return false;
249
250 if (mask & JOBCTL_STOP_SIGMASK)
251 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
252
253 task->jobctl |= mask;
254 return true;
255}
256
257/**
258 * task_clear_jobctl_trapping - clear jobctl trapping bit
259 * @task: target task
260 *
261 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
262 * Clear it and wake up the ptracer. Note that we don't need any further
263 * locking. @task->siglock guarantees that @task->parent points to the
264 * ptracer.
265 *
266 * CONTEXT:
267 * Must be called with @task->sighand->siglock held.
268 */
269void task_clear_jobctl_trapping(struct task_struct *task)
270{
271 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
272 task->jobctl &= ~JOBCTL_TRAPPING;
273 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
274 }
275}
276
277/**
278 * task_clear_jobctl_pending - clear jobctl pending bits
279 * @task: target task
280 * @mask: pending bits to clear
281 *
282 * Clear @mask from @task->jobctl. @mask must be subset of
283 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
284 * STOP bits are cleared together.
285 *
286 * If clearing of @mask leaves no stop or trap pending, this function calls
287 * task_clear_jobctl_trapping().
288 *
289 * CONTEXT:
290 * Must be called with @task->sighand->siglock held.
291 */
292void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
293{
294 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
295
296 if (mask & JOBCTL_STOP_PENDING)
297 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
298
299 task->jobctl &= ~mask;
300
301 if (!(task->jobctl & JOBCTL_PENDING_MASK))
302 task_clear_jobctl_trapping(task);
303}
304
305/**
306 * task_participate_group_stop - participate in a group stop
307 * @task: task participating in a group stop
308 *
309 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
310 * Group stop states are cleared and the group stop count is consumed if
311 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
312 * stop, the appropriate %SIGNAL_* flags are set.
313 *
314 * CONTEXT:
315 * Must be called with @task->sighand->siglock held.
316 *
317 * RETURNS:
318 * %true if group stop completion should be notified to the parent, %false
319 * otherwise.
320 */
321static bool task_participate_group_stop(struct task_struct *task)
322{
323 struct signal_struct *sig = task->signal;
324 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
325
326 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
327
328 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
329
330 if (!consume)
331 return false;
332
333 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
334 sig->group_stop_count--;
335
336 /*
337 * Tell the caller to notify completion iff we are entering into a
338 * fresh group stop. Read comment in do_signal_stop() for details.
339 */
340 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
341 sig->flags = SIGNAL_STOP_STOPPED;
342 return true;
343 }
344 return false;
345}
346
347/*
348 * allocate a new signal queue record
349 * - this may be called without locks if and only if t == current, otherwise an
350 * appropriate lock must be held to stop the target task from exiting
351 */
352static struct sigqueue *
353__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
354{
355 struct sigqueue *q = NULL;
356 struct user_struct *user;
357
358 /*
359 * Protect access to @t credentials. This can go away when all
360 * callers hold rcu read lock.
361 */
362 rcu_read_lock();
363 user = get_uid(__task_cred(t)->user);
364 atomic_inc(&user->sigpending);
365 rcu_read_unlock();
366
367 if (override_rlimit ||
368 atomic_read(&user->sigpending) <=
369 task_rlimit(t, RLIMIT_SIGPENDING)) {
370 q = kmem_cache_alloc(sigqueue_cachep, flags);
371 } else {
372 print_dropped_signal(sig);
373 }
374
375 if (unlikely(q == NULL)) {
376 atomic_dec(&user->sigpending);
377 free_uid(user);
378 } else {
379 INIT_LIST_HEAD(&q->list);
380 q->flags = 0;
381 q->user = user;
382 }
383
384 return q;
385}
386
387static void __sigqueue_free(struct sigqueue *q)
388{
389 if (q->flags & SIGQUEUE_PREALLOC)
390 return;
391 atomic_dec(&q->user->sigpending);
392 free_uid(q->user);
393 kmem_cache_free(sigqueue_cachep, q);
394}
395
396void flush_sigqueue(struct sigpending *queue)
397{
398 struct sigqueue *q;
399
400 sigemptyset(&queue->signal);
401 while (!list_empty(&queue->list)) {
402 q = list_entry(queue->list.next, struct sigqueue , list);
403 list_del_init(&q->list);
404 __sigqueue_free(q);
405 }
406}
407
408/*
409 * Flush all pending signals for a task.
410 */
411void __flush_signals(struct task_struct *t)
412{
413 clear_tsk_thread_flag(t, TIF_SIGPENDING);
414 flush_sigqueue(&t->pending);
415 flush_sigqueue(&t->signal->shared_pending);
416}
417
418void flush_signals(struct task_struct *t)
419{
420 unsigned long flags;
421
422 spin_lock_irqsave(&t->sighand->siglock, flags);
423 __flush_signals(t);
424 spin_unlock_irqrestore(&t->sighand->siglock, flags);
425}
426
427static void __flush_itimer_signals(struct sigpending *pending)
428{
429 sigset_t signal, retain;
430 struct sigqueue *q, *n;
431
432 signal = pending->signal;
433 sigemptyset(&retain);
434
435 list_for_each_entry_safe(q, n, &pending->list, list) {
436 int sig = q->info.si_signo;
437
438 if (likely(q->info.si_code != SI_TIMER)) {
439 sigaddset(&retain, sig);
440 } else {
441 sigdelset(&signal, sig);
442 list_del_init(&q->list);
443 __sigqueue_free(q);
444 }
445 }
446
447 sigorsets(&pending->signal, &signal, &retain);
448}
449
450void flush_itimer_signals(void)
451{
452 struct task_struct *tsk = current;
453 unsigned long flags;
454
455 spin_lock_irqsave(&tsk->sighand->siglock, flags);
456 __flush_itimer_signals(&tsk->pending);
457 __flush_itimer_signals(&tsk->signal->shared_pending);
458 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
459}
460
461void ignore_signals(struct task_struct *t)
462{
463 int i;
464
465 for (i = 0; i < _NSIG; ++i)
466 t->sighand->action[i].sa.sa_handler = SIG_IGN;
467
468 flush_signals(t);
469}
470
471/*
472 * Flush all handlers for a task.
473 */
474
475void
476flush_signal_handlers(struct task_struct *t, int force_default)
477{
478 int i;
479 struct k_sigaction *ka = &t->sighand->action[0];
480 for (i = _NSIG ; i != 0 ; i--) {
481 if (force_default || ka->sa.sa_handler != SIG_IGN)
482 ka->sa.sa_handler = SIG_DFL;
483 ka->sa.sa_flags = 0;
484 sigemptyset(&ka->sa.sa_mask);
485 ka++;
486 }
487}
488
489int unhandled_signal(struct task_struct *tsk, int sig)
490{
491 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
492 if (is_global_init(tsk))
493 return 1;
494 if (handler != SIG_IGN && handler != SIG_DFL)
495 return 0;
496 /* if ptraced, let the tracer determine */
497 return !tsk->ptrace;
498}
499
500/*
501 * Notify the system that a driver wants to block all signals for this
502 * process, and wants to be notified if any signals at all were to be
503 * sent/acted upon. If the notifier routine returns non-zero, then the
504 * signal will be acted upon after all. If the notifier routine returns 0,
505 * then then signal will be blocked. Only one block per process is
506 * allowed. priv is a pointer to private data that the notifier routine
507 * can use to determine if the signal should be blocked or not.
508 */
509void
510block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
511{
512 unsigned long flags;
513
514 spin_lock_irqsave(¤t->sighand->siglock, flags);
515 current->notifier_mask = mask;
516 current->notifier_data = priv;
517 current->notifier = notifier;
518 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
519}
520
521/* Notify the system that blocking has ended. */
522
523void
524unblock_all_signals(void)
525{
526 unsigned long flags;
527
528 spin_lock_irqsave(¤t->sighand->siglock, flags);
529 current->notifier = NULL;
530 current->notifier_data = NULL;
531 recalc_sigpending();
532 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
533}
534
535static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
536{
537 struct sigqueue *q, *first = NULL;
538
539 /*
540 * Collect the siginfo appropriate to this signal. Check if
541 * there is another siginfo for the same signal.
542 */
543 list_for_each_entry(q, &list->list, list) {
544 if (q->info.si_signo == sig) {
545 if (first)
546 goto still_pending;
547 first = q;
548 }
549 }
550
551 sigdelset(&list->signal, sig);
552
553 if (first) {
554still_pending:
555 list_del_init(&first->list);
556 copy_siginfo(info, &first->info);
557 __sigqueue_free(first);
558 } else {
559 /*
560 * Ok, it wasn't in the queue. This must be
561 * a fast-pathed signal or we must have been
562 * out of queue space. So zero out the info.
563 */
564 info->si_signo = sig;
565 info->si_errno = 0;
566 info->si_code = SI_USER;
567 info->si_pid = 0;
568 info->si_uid = 0;
569 }
570}
571
572static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
573 siginfo_t *info)
574{
575 int sig = next_signal(pending, mask);
576
577 if (sig) {
578 if (current->notifier) {
579 if (sigismember(current->notifier_mask, sig)) {
580 if (!(current->notifier)(current->notifier_data)) {
581 clear_thread_flag(TIF_SIGPENDING);
582 return 0;
583 }
584 }
585 }
586
587 collect_signal(sig, pending, info);
588 }
589
590 return sig;
591}
592
593/*
594 * Dequeue a signal and return the element to the caller, which is
595 * expected to free it.
596 *
597 * All callers have to hold the siglock.
598 */
599int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
600{
601 int signr;
602
603 /* We only dequeue private signals from ourselves, we don't let
604 * signalfd steal them
605 */
606 signr = __dequeue_signal(&tsk->pending, mask, info);
607 if (!signr) {
608 signr = __dequeue_signal(&tsk->signal->shared_pending,
609 mask, info);
610 /*
611 * itimer signal ?
612 *
613 * itimers are process shared and we restart periodic
614 * itimers in the signal delivery path to prevent DoS
615 * attacks in the high resolution timer case. This is
616 * compliant with the old way of self-restarting
617 * itimers, as the SIGALRM is a legacy signal and only
618 * queued once. Changing the restart behaviour to
619 * restart the timer in the signal dequeue path is
620 * reducing the timer noise on heavy loaded !highres
621 * systems too.
622 */
623 if (unlikely(signr == SIGALRM)) {
624 struct hrtimer *tmr = &tsk->signal->real_timer;
625
626 if (!hrtimer_is_queued(tmr) &&
627 tsk->signal->it_real_incr.tv64 != 0) {
628 hrtimer_forward(tmr, tmr->base->get_time(),
629 tsk->signal->it_real_incr);
630 hrtimer_restart(tmr);
631 }
632 }
633 }
634
635 recalc_sigpending();
636 if (!signr)
637 return 0;
638
639 if (unlikely(sig_kernel_stop(signr))) {
640 /*
641 * Set a marker that we have dequeued a stop signal. Our
642 * caller might release the siglock and then the pending
643 * stop signal it is about to process is no longer in the
644 * pending bitmasks, but must still be cleared by a SIGCONT
645 * (and overruled by a SIGKILL). So those cases clear this
646 * shared flag after we've set it. Note that this flag may
647 * remain set after the signal we return is ignored or
648 * handled. That doesn't matter because its only purpose
649 * is to alert stop-signal processing code when another
650 * processor has come along and cleared the flag.
651 */
652 current->jobctl |= JOBCTL_STOP_DEQUEUED;
653 }
654 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
655 /*
656 * Release the siglock to ensure proper locking order
657 * of timer locks outside of siglocks. Note, we leave
658 * irqs disabled here, since the posix-timers code is
659 * about to disable them again anyway.
660 */
661 spin_unlock(&tsk->sighand->siglock);
662 do_schedule_next_timer(info);
663 spin_lock(&tsk->sighand->siglock);
664 }
665 return signr;
666}
667
668/*
669 * Tell a process that it has a new active signal..
670 *
671 * NOTE! we rely on the previous spin_lock to
672 * lock interrupts for us! We can only be called with
673 * "siglock" held, and the local interrupt must
674 * have been disabled when that got acquired!
675 *
676 * No need to set need_resched since signal event passing
677 * goes through ->blocked
678 */
679void signal_wake_up(struct task_struct *t, int resume)
680{
681 unsigned int mask;
682
683 set_tsk_thread_flag(t, TIF_SIGPENDING);
684
685 /*
686 * For SIGKILL, we want to wake it up in the stopped/traced/killable
687 * case. We don't check t->state here because there is a race with it
688 * executing another processor and just now entering stopped state.
689 * By using wake_up_state, we ensure the process will wake up and
690 * handle its death signal.
691 */
692 mask = TASK_INTERRUPTIBLE;
693 if (resume)
694 mask |= TASK_WAKEKILL;
695 if (!wake_up_state(t, mask))
696 kick_process(t);
697}
698
699/*
700 * Remove signals in mask from the pending set and queue.
701 * Returns 1 if any signals were found.
702 *
703 * All callers must be holding the siglock.
704 *
705 * This version takes a sigset mask and looks at all signals,
706 * not just those in the first mask word.
707 */
708static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
709{
710 struct sigqueue *q, *n;
711 sigset_t m;
712
713 sigandsets(&m, mask, &s->signal);
714 if (sigisemptyset(&m))
715 return 0;
716
717 sigandnsets(&s->signal, &s->signal, mask);
718 list_for_each_entry_safe(q, n, &s->list, list) {
719 if (sigismember(mask, q->info.si_signo)) {
720 list_del_init(&q->list);
721 __sigqueue_free(q);
722 }
723 }
724 return 1;
725}
726/*
727 * Remove signals in mask from the pending set and queue.
728 * Returns 1 if any signals were found.
729 *
730 * All callers must be holding the siglock.
731 */
732static int rm_from_queue(unsigned long mask, struct sigpending *s)
733{
734 struct sigqueue *q, *n;
735
736 if (!sigtestsetmask(&s->signal, mask))
737 return 0;
738
739 sigdelsetmask(&s->signal, mask);
740 list_for_each_entry_safe(q, n, &s->list, list) {
741 if (q->info.si_signo < SIGRTMIN &&
742 (mask & sigmask(q->info.si_signo))) {
743 list_del_init(&q->list);
744 __sigqueue_free(q);
745 }
746 }
747 return 1;
748}
749
750static inline int is_si_special(const struct siginfo *info)
751{
752 return info <= SEND_SIG_FORCED;
753}
754
755static inline bool si_fromuser(const struct siginfo *info)
756{
757 return info == SEND_SIG_NOINFO ||
758 (!is_si_special(info) && SI_FROMUSER(info));
759}
760
761/*
762 * called with RCU read lock from check_kill_permission()
763 */
764static int kill_ok_by_cred(struct task_struct *t)
765{
766 const struct cred *cred = current_cred();
767 const struct cred *tcred = __task_cred(t);
768
769 if (cred->user->user_ns == tcred->user->user_ns &&
770 (cred->euid == tcred->suid ||
771 cred->euid == tcred->uid ||
772 cred->uid == tcred->suid ||
773 cred->uid == tcred->uid))
774 return 1;
775
776 if (ns_capable(tcred->user->user_ns, CAP_KILL))
777 return 1;
778
779 return 0;
780}
781
782/*
783 * Bad permissions for sending the signal
784 * - the caller must hold the RCU read lock
785 */
786static int check_kill_permission(int sig, struct siginfo *info,
787 struct task_struct *t)
788{
789 struct pid *sid;
790 int error;
791
792 if (!valid_signal(sig))
793 return -EINVAL;
794
795 if (!si_fromuser(info))
796 return 0;
797
798 error = audit_signal_info(sig, t); /* Let audit system see the signal */
799 if (error)
800 return error;
801
802 if (!same_thread_group(current, t) &&
803 !kill_ok_by_cred(t)) {
804 switch (sig) {
805 case SIGCONT:
806 sid = task_session(t);
807 /*
808 * We don't return the error if sid == NULL. The
809 * task was unhashed, the caller must notice this.
810 */
811 if (!sid || sid == task_session(current))
812 break;
813 default:
814 return -EPERM;
815 }
816 }
817
818 return security_task_kill(t, info, sig, 0);
819}
820
821/**
822 * ptrace_trap_notify - schedule trap to notify ptracer
823 * @t: tracee wanting to notify tracer
824 *
825 * This function schedules sticky ptrace trap which is cleared on the next
826 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
827 * ptracer.
828 *
829 * If @t is running, STOP trap will be taken. If trapped for STOP and
830 * ptracer is listening for events, tracee is woken up so that it can
831 * re-trap for the new event. If trapped otherwise, STOP trap will be
832 * eventually taken without returning to userland after the existing traps
833 * are finished by PTRACE_CONT.
834 *
835 * CONTEXT:
836 * Must be called with @task->sighand->siglock held.
837 */
838static void ptrace_trap_notify(struct task_struct *t)
839{
840 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
841 assert_spin_locked(&t->sighand->siglock);
842
843 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
844 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
845}
846
847/*
848 * Handle magic process-wide effects of stop/continue signals. Unlike
849 * the signal actions, these happen immediately at signal-generation
850 * time regardless of blocking, ignoring, or handling. This does the
851 * actual continuing for SIGCONT, but not the actual stopping for stop
852 * signals. The process stop is done as a signal action for SIG_DFL.
853 *
854 * Returns true if the signal should be actually delivered, otherwise
855 * it should be dropped.
856 */
857static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
858{
859 struct signal_struct *signal = p->signal;
860 struct task_struct *t;
861
862 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
863 /*
864 * The process is in the middle of dying, nothing to do.
865 */
866 } else if (sig_kernel_stop(sig)) {
867 /*
868 * This is a stop signal. Remove SIGCONT from all queues.
869 */
870 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
871 t = p;
872 do {
873 rm_from_queue(sigmask(SIGCONT), &t->pending);
874 } while_each_thread(p, t);
875 } else if (sig == SIGCONT) {
876 unsigned int why;
877 /*
878 * Remove all stop signals from all queues, wake all threads.
879 */
880 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
881 t = p;
882 do {
883 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
884 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
885 if (likely(!(t->ptrace & PT_SEIZED)))
886 wake_up_state(t, __TASK_STOPPED);
887 else
888 ptrace_trap_notify(t);
889 } while_each_thread(p, t);
890
891 /*
892 * Notify the parent with CLD_CONTINUED if we were stopped.
893 *
894 * If we were in the middle of a group stop, we pretend it
895 * was already finished, and then continued. Since SIGCHLD
896 * doesn't queue we report only CLD_STOPPED, as if the next
897 * CLD_CONTINUED was dropped.
898 */
899 why = 0;
900 if (signal->flags & SIGNAL_STOP_STOPPED)
901 why |= SIGNAL_CLD_CONTINUED;
902 else if (signal->group_stop_count)
903 why |= SIGNAL_CLD_STOPPED;
904
905 if (why) {
906 /*
907 * The first thread which returns from do_signal_stop()
908 * will take ->siglock, notice SIGNAL_CLD_MASK, and
909 * notify its parent. See get_signal_to_deliver().
910 */
911 signal->flags = why | SIGNAL_STOP_CONTINUED;
912 signal->group_stop_count = 0;
913 signal->group_exit_code = 0;
914 }
915 }
916
917 return !sig_ignored(p, sig, from_ancestor_ns);
918}
919
920/*
921 * Test if P wants to take SIG. After we've checked all threads with this,
922 * it's equivalent to finding no threads not blocking SIG. Any threads not
923 * blocking SIG were ruled out because they are not running and already
924 * have pending signals. Such threads will dequeue from the shared queue
925 * as soon as they're available, so putting the signal on the shared queue
926 * will be equivalent to sending it to one such thread.
927 */
928static inline int wants_signal(int sig, struct task_struct *p)
929{
930 if (sigismember(&p->blocked, sig))
931 return 0;
932 if (p->flags & PF_EXITING)
933 return 0;
934 if (sig == SIGKILL)
935 return 1;
936 if (task_is_stopped_or_traced(p))
937 return 0;
938 return task_curr(p) || !signal_pending(p);
939}
940
941static void complete_signal(int sig, struct task_struct *p, int group)
942{
943 struct signal_struct *signal = p->signal;
944 struct task_struct *t;
945
946 /*
947 * Now find a thread we can wake up to take the signal off the queue.
948 *
949 * If the main thread wants the signal, it gets first crack.
950 * Probably the least surprising to the average bear.
951 */
952 if (wants_signal(sig, p))
953 t = p;
954 else if (!group || thread_group_empty(p))
955 /*
956 * There is just one thread and it does not need to be woken.
957 * It will dequeue unblocked signals before it runs again.
958 */
959 return;
960 else {
961 /*
962 * Otherwise try to find a suitable thread.
963 */
964 t = signal->curr_target;
965 while (!wants_signal(sig, t)) {
966 t = next_thread(t);
967 if (t == signal->curr_target)
968 /*
969 * No thread needs to be woken.
970 * Any eligible threads will see
971 * the signal in the queue soon.
972 */
973 return;
974 }
975 signal->curr_target = t;
976 }
977
978 /*
979 * Found a killable thread. If the signal will be fatal,
980 * then start taking the whole group down immediately.
981 */
982 if (sig_fatal(p, sig) &&
983 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
984 !sigismember(&t->real_blocked, sig) &&
985 (sig == SIGKILL || !t->ptrace)) {
986 /*
987 * This signal will be fatal to the whole group.
988 */
989 if (!sig_kernel_coredump(sig)) {
990 /*
991 * Start a group exit and wake everybody up.
992 * This way we don't have other threads
993 * running and doing things after a slower
994 * thread has the fatal signal pending.
995 */
996 signal->flags = SIGNAL_GROUP_EXIT;
997 signal->group_exit_code = sig;
998 signal->group_stop_count = 0;
999 t = p;
1000 do {
1001 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1002 sigaddset(&t->pending.signal, SIGKILL);
1003 signal_wake_up(t, 1);
1004 } while_each_thread(p, t);
1005 return;
1006 }
1007 }
1008
1009 /*
1010 * The signal is already in the shared-pending queue.
1011 * Tell the chosen thread to wake up and dequeue it.
1012 */
1013 signal_wake_up(t, sig == SIGKILL);
1014 return;
1015}
1016
1017static inline int legacy_queue(struct sigpending *signals, int sig)
1018{
1019 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1020}
1021
1022static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1023 int group, int from_ancestor_ns)
1024{
1025 struct sigpending *pending;
1026 struct sigqueue *q;
1027 int override_rlimit;
1028
1029 trace_signal_generate(sig, info, t);
1030
1031 assert_spin_locked(&t->sighand->siglock);
1032
1033 if (!prepare_signal(sig, t, from_ancestor_ns))
1034 return 0;
1035
1036 pending = group ? &t->signal->shared_pending : &t->pending;
1037 /*
1038 * Short-circuit ignored signals and support queuing
1039 * exactly one non-rt signal, so that we can get more
1040 * detailed information about the cause of the signal.
1041 */
1042 if (legacy_queue(pending, sig))
1043 return 0;
1044 /*
1045 * fast-pathed signals for kernel-internal things like SIGSTOP
1046 * or SIGKILL.
1047 */
1048 if (info == SEND_SIG_FORCED)
1049 goto out_set;
1050
1051 /*
1052 * Real-time signals must be queued if sent by sigqueue, or
1053 * some other real-time mechanism. It is implementation
1054 * defined whether kill() does so. We attempt to do so, on
1055 * the principle of least surprise, but since kill is not
1056 * allowed to fail with EAGAIN when low on memory we just
1057 * make sure at least one signal gets delivered and don't
1058 * pass on the info struct.
1059 */
1060 if (sig < SIGRTMIN)
1061 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1062 else
1063 override_rlimit = 0;
1064
1065 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1066 override_rlimit);
1067 if (q) {
1068 list_add_tail(&q->list, &pending->list);
1069 switch ((unsigned long) info) {
1070 case (unsigned long) SEND_SIG_NOINFO:
1071 q->info.si_signo = sig;
1072 q->info.si_errno = 0;
1073 q->info.si_code = SI_USER;
1074 q->info.si_pid = task_tgid_nr_ns(current,
1075 task_active_pid_ns(t));
1076 q->info.si_uid = current_uid();
1077 break;
1078 case (unsigned long) SEND_SIG_PRIV:
1079 q->info.si_signo = sig;
1080 q->info.si_errno = 0;
1081 q->info.si_code = SI_KERNEL;
1082 q->info.si_pid = 0;
1083 q->info.si_uid = 0;
1084 break;
1085 default:
1086 copy_siginfo(&q->info, info);
1087 if (from_ancestor_ns)
1088 q->info.si_pid = 0;
1089 break;
1090 }
1091 } else if (!is_si_special(info)) {
1092 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1093 /*
1094 * Queue overflow, abort. We may abort if the
1095 * signal was rt and sent by user using something
1096 * other than kill().
1097 */
1098 trace_signal_overflow_fail(sig, group, info);
1099 return -EAGAIN;
1100 } else {
1101 /*
1102 * This is a silent loss of information. We still
1103 * send the signal, but the *info bits are lost.
1104 */
1105 trace_signal_lose_info(sig, group, info);
1106 }
1107 }
1108
1109out_set:
1110 signalfd_notify(t, sig);
1111 sigaddset(&pending->signal, sig);
1112 complete_signal(sig, t, group);
1113 return 0;
1114}
1115
1116static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1117 int group)
1118{
1119 int from_ancestor_ns = 0;
1120
1121#ifdef CONFIG_PID_NS
1122 from_ancestor_ns = si_fromuser(info) &&
1123 !task_pid_nr_ns(current, task_active_pid_ns(t));
1124#endif
1125
1126 return __send_signal(sig, info, t, group, from_ancestor_ns);
1127}
1128
1129static void print_fatal_signal(struct pt_regs *regs, int signr)
1130{
1131 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1132 current->comm, task_pid_nr(current), signr);
1133
1134#if defined(__i386__) && !defined(__arch_um__)
1135 printk("code at %08lx: ", regs->ip);
1136 {
1137 int i;
1138 for (i = 0; i < 16; i++) {
1139 unsigned char insn;
1140
1141 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1142 break;
1143 printk("%02x ", insn);
1144 }
1145 }
1146#endif
1147 printk("\n");
1148 preempt_disable();
1149 show_regs(regs);
1150 preempt_enable();
1151}
1152
1153static int __init setup_print_fatal_signals(char *str)
1154{
1155 get_option (&str, &print_fatal_signals);
1156
1157 return 1;
1158}
1159
1160__setup("print-fatal-signals=", setup_print_fatal_signals);
1161
1162int
1163__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1164{
1165 return send_signal(sig, info, p, 1);
1166}
1167
1168static int
1169specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1170{
1171 return send_signal(sig, info, t, 0);
1172}
1173
1174int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1175 bool group)
1176{
1177 unsigned long flags;
1178 int ret = -ESRCH;
1179
1180 if (lock_task_sighand(p, &flags)) {
1181 ret = send_signal(sig, info, p, group);
1182 unlock_task_sighand(p, &flags);
1183 }
1184
1185 return ret;
1186}
1187
1188/*
1189 * Force a signal that the process can't ignore: if necessary
1190 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1191 *
1192 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1193 * since we do not want to have a signal handler that was blocked
1194 * be invoked when user space had explicitly blocked it.
1195 *
1196 * We don't want to have recursive SIGSEGV's etc, for example,
1197 * that is why we also clear SIGNAL_UNKILLABLE.
1198 */
1199int
1200force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1201{
1202 unsigned long int flags;
1203 int ret, blocked, ignored;
1204 struct k_sigaction *action;
1205
1206 spin_lock_irqsave(&t->sighand->siglock, flags);
1207 action = &t->sighand->action[sig-1];
1208 ignored = action->sa.sa_handler == SIG_IGN;
1209 blocked = sigismember(&t->blocked, sig);
1210 if (blocked || ignored) {
1211 action->sa.sa_handler = SIG_DFL;
1212 if (blocked) {
1213 sigdelset(&t->blocked, sig);
1214 recalc_sigpending_and_wake(t);
1215 }
1216 }
1217 if (action->sa.sa_handler == SIG_DFL)
1218 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1219 ret = specific_send_sig_info(sig, info, t);
1220 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1221
1222 return ret;
1223}
1224
1225/*
1226 * Nuke all other threads in the group.
1227 */
1228int zap_other_threads(struct task_struct *p)
1229{
1230 struct task_struct *t = p;
1231 int count = 0;
1232
1233 p->signal->group_stop_count = 0;
1234
1235 while_each_thread(p, t) {
1236 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1237 count++;
1238
1239 /* Don't bother with already dead threads */
1240 if (t->exit_state)
1241 continue;
1242 sigaddset(&t->pending.signal, SIGKILL);
1243 signal_wake_up(t, 1);
1244 }
1245
1246 return count;
1247}
1248
1249struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1250 unsigned long *flags)
1251{
1252 struct sighand_struct *sighand;
1253
1254 for (;;) {
1255 local_irq_save(*flags);
1256 rcu_read_lock();
1257 sighand = rcu_dereference(tsk->sighand);
1258 if (unlikely(sighand == NULL)) {
1259 rcu_read_unlock();
1260 local_irq_restore(*flags);
1261 break;
1262 }
1263
1264 spin_lock(&sighand->siglock);
1265 if (likely(sighand == tsk->sighand)) {
1266 rcu_read_unlock();
1267 break;
1268 }
1269 spin_unlock(&sighand->siglock);
1270 rcu_read_unlock();
1271 local_irq_restore(*flags);
1272 }
1273
1274 return sighand;
1275}
1276
1277/*
1278 * send signal info to all the members of a group
1279 */
1280int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1281{
1282 int ret;
1283
1284 rcu_read_lock();
1285 ret = check_kill_permission(sig, info, p);
1286 rcu_read_unlock();
1287
1288 if (!ret && sig)
1289 ret = do_send_sig_info(sig, info, p, true);
1290
1291 return ret;
1292}
1293
1294/*
1295 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1296 * control characters do (^C, ^Z etc)
1297 * - the caller must hold at least a readlock on tasklist_lock
1298 */
1299int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1300{
1301 struct task_struct *p = NULL;
1302 int retval, success;
1303
1304 success = 0;
1305 retval = -ESRCH;
1306 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1307 int err = group_send_sig_info(sig, info, p);
1308 success |= !err;
1309 retval = err;
1310 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1311 return success ? 0 : retval;
1312}
1313
1314int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1315{
1316 int error = -ESRCH;
1317 struct task_struct *p;
1318
1319 rcu_read_lock();
1320retry:
1321 p = pid_task(pid, PIDTYPE_PID);
1322 if (p) {
1323 error = group_send_sig_info(sig, info, p);
1324 if (unlikely(error == -ESRCH))
1325 /*
1326 * The task was unhashed in between, try again.
1327 * If it is dead, pid_task() will return NULL,
1328 * if we race with de_thread() it will find the
1329 * new leader.
1330 */
1331 goto retry;
1332 }
1333 rcu_read_unlock();
1334
1335 return error;
1336}
1337
1338int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1339{
1340 int error;
1341 rcu_read_lock();
1342 error = kill_pid_info(sig, info, find_vpid(pid));
1343 rcu_read_unlock();
1344 return error;
1345}
1346
1347/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1348int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1349 uid_t uid, uid_t euid, u32 secid)
1350{
1351 int ret = -EINVAL;
1352 struct task_struct *p;
1353 const struct cred *pcred;
1354 unsigned long flags;
1355
1356 if (!valid_signal(sig))
1357 return ret;
1358
1359 rcu_read_lock();
1360 p = pid_task(pid, PIDTYPE_PID);
1361 if (!p) {
1362 ret = -ESRCH;
1363 goto out_unlock;
1364 }
1365 pcred = __task_cred(p);
1366 if (si_fromuser(info) &&
1367 euid != pcred->suid && euid != pcred->uid &&
1368 uid != pcred->suid && uid != pcred->uid) {
1369 ret = -EPERM;
1370 goto out_unlock;
1371 }
1372 ret = security_task_kill(p, info, sig, secid);
1373 if (ret)
1374 goto out_unlock;
1375
1376 if (sig) {
1377 if (lock_task_sighand(p, &flags)) {
1378 ret = __send_signal(sig, info, p, 1, 0);
1379 unlock_task_sighand(p, &flags);
1380 } else
1381 ret = -ESRCH;
1382 }
1383out_unlock:
1384 rcu_read_unlock();
1385 return ret;
1386}
1387EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1388
1389/*
1390 * kill_something_info() interprets pid in interesting ways just like kill(2).
1391 *
1392 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1393 * is probably wrong. Should make it like BSD or SYSV.
1394 */
1395
1396static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1397{
1398 int ret;
1399
1400 if (pid > 0) {
1401 rcu_read_lock();
1402 ret = kill_pid_info(sig, info, find_vpid(pid));
1403 rcu_read_unlock();
1404 return ret;
1405 }
1406
1407 read_lock(&tasklist_lock);
1408 if (pid != -1) {
1409 ret = __kill_pgrp_info(sig, info,
1410 pid ? find_vpid(-pid) : task_pgrp(current));
1411 } else {
1412 int retval = 0, count = 0;
1413 struct task_struct * p;
1414
1415 for_each_process(p) {
1416 if (task_pid_vnr(p) > 1 &&
1417 !same_thread_group(p, current)) {
1418 int err = group_send_sig_info(sig, info, p);
1419 ++count;
1420 if (err != -EPERM)
1421 retval = err;
1422 }
1423 }
1424 ret = count ? retval : -ESRCH;
1425 }
1426 read_unlock(&tasklist_lock);
1427
1428 return ret;
1429}
1430
1431/*
1432 * These are for backward compatibility with the rest of the kernel source.
1433 */
1434
1435int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1436{
1437 /*
1438 * Make sure legacy kernel users don't send in bad values
1439 * (normal paths check this in check_kill_permission).
1440 */
1441 if (!valid_signal(sig))
1442 return -EINVAL;
1443
1444 return do_send_sig_info(sig, info, p, false);
1445}
1446
1447#define __si_special(priv) \
1448 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1449
1450int
1451send_sig(int sig, struct task_struct *p, int priv)
1452{
1453 return send_sig_info(sig, __si_special(priv), p);
1454}
1455
1456void
1457force_sig(int sig, struct task_struct *p)
1458{
1459 force_sig_info(sig, SEND_SIG_PRIV, p);
1460}
1461
1462/*
1463 * When things go south during signal handling, we
1464 * will force a SIGSEGV. And if the signal that caused
1465 * the problem was already a SIGSEGV, we'll want to
1466 * make sure we don't even try to deliver the signal..
1467 */
1468int
1469force_sigsegv(int sig, struct task_struct *p)
1470{
1471 if (sig == SIGSEGV) {
1472 unsigned long flags;
1473 spin_lock_irqsave(&p->sighand->siglock, flags);
1474 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1475 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1476 }
1477 force_sig(SIGSEGV, p);
1478 return 0;
1479}
1480
1481int kill_pgrp(struct pid *pid, int sig, int priv)
1482{
1483 int ret;
1484
1485 read_lock(&tasklist_lock);
1486 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1487 read_unlock(&tasklist_lock);
1488
1489 return ret;
1490}
1491EXPORT_SYMBOL(kill_pgrp);
1492
1493int kill_pid(struct pid *pid, int sig, int priv)
1494{
1495 return kill_pid_info(sig, __si_special(priv), pid);
1496}
1497EXPORT_SYMBOL(kill_pid);
1498
1499/*
1500 * These functions support sending signals using preallocated sigqueue
1501 * structures. This is needed "because realtime applications cannot
1502 * afford to lose notifications of asynchronous events, like timer
1503 * expirations or I/O completions". In the case of POSIX Timers
1504 * we allocate the sigqueue structure from the timer_create. If this
1505 * allocation fails we are able to report the failure to the application
1506 * with an EAGAIN error.
1507 */
1508struct sigqueue *sigqueue_alloc(void)
1509{
1510 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1511
1512 if (q)
1513 q->flags |= SIGQUEUE_PREALLOC;
1514
1515 return q;
1516}
1517
1518void sigqueue_free(struct sigqueue *q)
1519{
1520 unsigned long flags;
1521 spinlock_t *lock = ¤t->sighand->siglock;
1522
1523 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1524 /*
1525 * We must hold ->siglock while testing q->list
1526 * to serialize with collect_signal() or with
1527 * __exit_signal()->flush_sigqueue().
1528 */
1529 spin_lock_irqsave(lock, flags);
1530 q->flags &= ~SIGQUEUE_PREALLOC;
1531 /*
1532 * If it is queued it will be freed when dequeued,
1533 * like the "regular" sigqueue.
1534 */
1535 if (!list_empty(&q->list))
1536 q = NULL;
1537 spin_unlock_irqrestore(lock, flags);
1538
1539 if (q)
1540 __sigqueue_free(q);
1541}
1542
1543int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1544{
1545 int sig = q->info.si_signo;
1546 struct sigpending *pending;
1547 unsigned long flags;
1548 int ret;
1549
1550 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1551
1552 ret = -1;
1553 if (!likely(lock_task_sighand(t, &flags)))
1554 goto ret;
1555
1556 ret = 1; /* the signal is ignored */
1557 if (!prepare_signal(sig, t, 0))
1558 goto out;
1559
1560 ret = 0;
1561 if (unlikely(!list_empty(&q->list))) {
1562 /*
1563 * If an SI_TIMER entry is already queue just increment
1564 * the overrun count.
1565 */
1566 BUG_ON(q->info.si_code != SI_TIMER);
1567 q->info.si_overrun++;
1568 goto out;
1569 }
1570 q->info.si_overrun = 0;
1571
1572 signalfd_notify(t, sig);
1573 pending = group ? &t->signal->shared_pending : &t->pending;
1574 list_add_tail(&q->list, &pending->list);
1575 sigaddset(&pending->signal, sig);
1576 complete_signal(sig, t, group);
1577out:
1578 unlock_task_sighand(t, &flags);
1579ret:
1580 return ret;
1581}
1582
1583/*
1584 * Let a parent know about the death of a child.
1585 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1586 *
1587 * Returns true if our parent ignored us and so we've switched to
1588 * self-reaping.
1589 */
1590bool do_notify_parent(struct task_struct *tsk, int sig)
1591{
1592 struct siginfo info;
1593 unsigned long flags;
1594 struct sighand_struct *psig;
1595 bool autoreap = false;
1596
1597 BUG_ON(sig == -1);
1598
1599 /* do_notify_parent_cldstop should have been called instead. */
1600 BUG_ON(task_is_stopped_or_traced(tsk));
1601
1602 BUG_ON(!tsk->ptrace &&
1603 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1604
1605 info.si_signo = sig;
1606 info.si_errno = 0;
1607 /*
1608 * we are under tasklist_lock here so our parent is tied to
1609 * us and cannot exit and release its namespace.
1610 *
1611 * the only it can is to switch its nsproxy with sys_unshare,
1612 * bu uncharing pid namespaces is not allowed, so we'll always
1613 * see relevant namespace
1614 *
1615 * write_lock() currently calls preempt_disable() which is the
1616 * same as rcu_read_lock(), but according to Oleg, this is not
1617 * correct to rely on this
1618 */
1619 rcu_read_lock();
1620 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1621 info.si_uid = __task_cred(tsk)->uid;
1622 rcu_read_unlock();
1623
1624 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1625 tsk->signal->utime));
1626 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1627 tsk->signal->stime));
1628
1629 info.si_status = tsk->exit_code & 0x7f;
1630 if (tsk->exit_code & 0x80)
1631 info.si_code = CLD_DUMPED;
1632 else if (tsk->exit_code & 0x7f)
1633 info.si_code = CLD_KILLED;
1634 else {
1635 info.si_code = CLD_EXITED;
1636 info.si_status = tsk->exit_code >> 8;
1637 }
1638
1639 psig = tsk->parent->sighand;
1640 spin_lock_irqsave(&psig->siglock, flags);
1641 if (!tsk->ptrace && sig == SIGCHLD &&
1642 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1643 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1644 /*
1645 * We are exiting and our parent doesn't care. POSIX.1
1646 * defines special semantics for setting SIGCHLD to SIG_IGN
1647 * or setting the SA_NOCLDWAIT flag: we should be reaped
1648 * automatically and not left for our parent's wait4 call.
1649 * Rather than having the parent do it as a magic kind of
1650 * signal handler, we just set this to tell do_exit that we
1651 * can be cleaned up without becoming a zombie. Note that
1652 * we still call __wake_up_parent in this case, because a
1653 * blocked sys_wait4 might now return -ECHILD.
1654 *
1655 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1656 * is implementation-defined: we do (if you don't want
1657 * it, just use SIG_IGN instead).
1658 */
1659 autoreap = true;
1660 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1661 sig = 0;
1662 }
1663 if (valid_signal(sig) && sig)
1664 __group_send_sig_info(sig, &info, tsk->parent);
1665 __wake_up_parent(tsk, tsk->parent);
1666 spin_unlock_irqrestore(&psig->siglock, flags);
1667
1668 return autoreap;
1669}
1670
1671/**
1672 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1673 * @tsk: task reporting the state change
1674 * @for_ptracer: the notification is for ptracer
1675 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1676 *
1677 * Notify @tsk's parent that the stopped/continued state has changed. If
1678 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1679 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1680 *
1681 * CONTEXT:
1682 * Must be called with tasklist_lock at least read locked.
1683 */
1684static void do_notify_parent_cldstop(struct task_struct *tsk,
1685 bool for_ptracer, int why)
1686{
1687 struct siginfo info;
1688 unsigned long flags;
1689 struct task_struct *parent;
1690 struct sighand_struct *sighand;
1691
1692 if (for_ptracer) {
1693 parent = tsk->parent;
1694 } else {
1695 tsk = tsk->group_leader;
1696 parent = tsk->real_parent;
1697 }
1698
1699 info.si_signo = SIGCHLD;
1700 info.si_errno = 0;
1701 /*
1702 * see comment in do_notify_parent() about the following 4 lines
1703 */
1704 rcu_read_lock();
1705 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1706 info.si_uid = __task_cred(tsk)->uid;
1707 rcu_read_unlock();
1708
1709 info.si_utime = cputime_to_clock_t(tsk->utime);
1710 info.si_stime = cputime_to_clock_t(tsk->stime);
1711
1712 info.si_code = why;
1713 switch (why) {
1714 case CLD_CONTINUED:
1715 info.si_status = SIGCONT;
1716 break;
1717 case CLD_STOPPED:
1718 info.si_status = tsk->signal->group_exit_code & 0x7f;
1719 break;
1720 case CLD_TRAPPED:
1721 info.si_status = tsk->exit_code & 0x7f;
1722 break;
1723 default:
1724 BUG();
1725 }
1726
1727 sighand = parent->sighand;
1728 spin_lock_irqsave(&sighand->siglock, flags);
1729 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1730 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1731 __group_send_sig_info(SIGCHLD, &info, parent);
1732 /*
1733 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1734 */
1735 __wake_up_parent(tsk, parent);
1736 spin_unlock_irqrestore(&sighand->siglock, flags);
1737}
1738
1739static inline int may_ptrace_stop(void)
1740{
1741 if (!likely(current->ptrace))
1742 return 0;
1743 /*
1744 * Are we in the middle of do_coredump?
1745 * If so and our tracer is also part of the coredump stopping
1746 * is a deadlock situation, and pointless because our tracer
1747 * is dead so don't allow us to stop.
1748 * If SIGKILL was already sent before the caller unlocked
1749 * ->siglock we must see ->core_state != NULL. Otherwise it
1750 * is safe to enter schedule().
1751 */
1752 if (unlikely(current->mm->core_state) &&
1753 unlikely(current->mm == current->parent->mm))
1754 return 0;
1755
1756 return 1;
1757}
1758
1759/*
1760 * Return non-zero if there is a SIGKILL that should be waking us up.
1761 * Called with the siglock held.
1762 */
1763static int sigkill_pending(struct task_struct *tsk)
1764{
1765 return sigismember(&tsk->pending.signal, SIGKILL) ||
1766 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1767}
1768
1769/*
1770 * This must be called with current->sighand->siglock held.
1771 *
1772 * This should be the path for all ptrace stops.
1773 * We always set current->last_siginfo while stopped here.
1774 * That makes it a way to test a stopped process for
1775 * being ptrace-stopped vs being job-control-stopped.
1776 *
1777 * If we actually decide not to stop at all because the tracer
1778 * is gone, we keep current->exit_code unless clear_code.
1779 */
1780static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1781 __releases(¤t->sighand->siglock)
1782 __acquires(¤t->sighand->siglock)
1783{
1784 bool gstop_done = false;
1785
1786 if (arch_ptrace_stop_needed(exit_code, info)) {
1787 /*
1788 * The arch code has something special to do before a
1789 * ptrace stop. This is allowed to block, e.g. for faults
1790 * on user stack pages. We can't keep the siglock while
1791 * calling arch_ptrace_stop, so we must release it now.
1792 * To preserve proper semantics, we must do this before
1793 * any signal bookkeeping like checking group_stop_count.
1794 * Meanwhile, a SIGKILL could come in before we retake the
1795 * siglock. That must prevent us from sleeping in TASK_TRACED.
1796 * So after regaining the lock, we must check for SIGKILL.
1797 */
1798 spin_unlock_irq(¤t->sighand->siglock);
1799 arch_ptrace_stop(exit_code, info);
1800 spin_lock_irq(¤t->sighand->siglock);
1801 if (sigkill_pending(current))
1802 return;
1803 }
1804
1805 /*
1806 * We're committing to trapping. TRACED should be visible before
1807 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1808 * Also, transition to TRACED and updates to ->jobctl should be
1809 * atomic with respect to siglock and should be done after the arch
1810 * hook as siglock is released and regrabbed across it.
1811 */
1812 set_current_state(TASK_TRACED);
1813
1814 current->last_siginfo = info;
1815 current->exit_code = exit_code;
1816
1817 /*
1818 * If @why is CLD_STOPPED, we're trapping to participate in a group
1819 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1820 * across siglock relocks since INTERRUPT was scheduled, PENDING
1821 * could be clear now. We act as if SIGCONT is received after
1822 * TASK_TRACED is entered - ignore it.
1823 */
1824 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1825 gstop_done = task_participate_group_stop(current);
1826
1827 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1828 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1829 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1830 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1831
1832 /* entering a trap, clear TRAPPING */
1833 task_clear_jobctl_trapping(current);
1834
1835 spin_unlock_irq(¤t->sighand->siglock);
1836 read_lock(&tasklist_lock);
1837 if (may_ptrace_stop()) {
1838 /*
1839 * Notify parents of the stop.
1840 *
1841 * While ptraced, there are two parents - the ptracer and
1842 * the real_parent of the group_leader. The ptracer should
1843 * know about every stop while the real parent is only
1844 * interested in the completion of group stop. The states
1845 * for the two don't interact with each other. Notify
1846 * separately unless they're gonna be duplicates.
1847 */
1848 do_notify_parent_cldstop(current, true, why);
1849 if (gstop_done && ptrace_reparented(current))
1850 do_notify_parent_cldstop(current, false, why);
1851
1852 /*
1853 * Don't want to allow preemption here, because
1854 * sys_ptrace() needs this task to be inactive.
1855 *
1856 * XXX: implement read_unlock_no_resched().
1857 */
1858 preempt_disable();
1859 read_unlock(&tasklist_lock);
1860 preempt_enable_no_resched();
1861 schedule();
1862 } else {
1863 /*
1864 * By the time we got the lock, our tracer went away.
1865 * Don't drop the lock yet, another tracer may come.
1866 *
1867 * If @gstop_done, the ptracer went away between group stop
1868 * completion and here. During detach, it would have set
1869 * JOBCTL_STOP_PENDING on us and we'll re-enter
1870 * TASK_STOPPED in do_signal_stop() on return, so notifying
1871 * the real parent of the group stop completion is enough.
1872 */
1873 if (gstop_done)
1874 do_notify_parent_cldstop(current, false, why);
1875
1876 __set_current_state(TASK_RUNNING);
1877 if (clear_code)
1878 current->exit_code = 0;
1879 read_unlock(&tasklist_lock);
1880 }
1881
1882 /*
1883 * While in TASK_TRACED, we were considered "frozen enough".
1884 * Now that we woke up, it's crucial if we're supposed to be
1885 * frozen that we freeze now before running anything substantial.
1886 */
1887 try_to_freeze();
1888
1889 /*
1890 * We are back. Now reacquire the siglock before touching
1891 * last_siginfo, so that we are sure to have synchronized with
1892 * any signal-sending on another CPU that wants to examine it.
1893 */
1894 spin_lock_irq(¤t->sighand->siglock);
1895 current->last_siginfo = NULL;
1896
1897 /* LISTENING can be set only during STOP traps, clear it */
1898 current->jobctl &= ~JOBCTL_LISTENING;
1899
1900 /*
1901 * Queued signals ignored us while we were stopped for tracing.
1902 * So check for any that we should take before resuming user mode.
1903 * This sets TIF_SIGPENDING, but never clears it.
1904 */
1905 recalc_sigpending_tsk(current);
1906}
1907
1908static void ptrace_do_notify(int signr, int exit_code, int why)
1909{
1910 siginfo_t info;
1911
1912 memset(&info, 0, sizeof info);
1913 info.si_signo = signr;
1914 info.si_code = exit_code;
1915 info.si_pid = task_pid_vnr(current);
1916 info.si_uid = current_uid();
1917
1918 /* Let the debugger run. */
1919 ptrace_stop(exit_code, why, 1, &info);
1920}
1921
1922void ptrace_notify(int exit_code)
1923{
1924 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1925
1926 spin_lock_irq(¤t->sighand->siglock);
1927 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1928 spin_unlock_irq(¤t->sighand->siglock);
1929}
1930
1931/**
1932 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1933 * @signr: signr causing group stop if initiating
1934 *
1935 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1936 * and participate in it. If already set, participate in the existing
1937 * group stop. If participated in a group stop (and thus slept), %true is
1938 * returned with siglock released.
1939 *
1940 * If ptraced, this function doesn't handle stop itself. Instead,
1941 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1942 * untouched. The caller must ensure that INTERRUPT trap handling takes
1943 * places afterwards.
1944 *
1945 * CONTEXT:
1946 * Must be called with @current->sighand->siglock held, which is released
1947 * on %true return.
1948 *
1949 * RETURNS:
1950 * %false if group stop is already cancelled or ptrace trap is scheduled.
1951 * %true if participated in group stop.
1952 */
1953static bool do_signal_stop(int signr)
1954 __releases(¤t->sighand->siglock)
1955{
1956 struct signal_struct *sig = current->signal;
1957
1958 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1959 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1960 struct task_struct *t;
1961
1962 /* signr will be recorded in task->jobctl for retries */
1963 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1964
1965 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1966 unlikely(signal_group_exit(sig)))
1967 return false;
1968 /*
1969 * There is no group stop already in progress. We must
1970 * initiate one now.
1971 *
1972 * While ptraced, a task may be resumed while group stop is
1973 * still in effect and then receive a stop signal and
1974 * initiate another group stop. This deviates from the
1975 * usual behavior as two consecutive stop signals can't
1976 * cause two group stops when !ptraced. That is why we
1977 * also check !task_is_stopped(t) below.
1978 *
1979 * The condition can be distinguished by testing whether
1980 * SIGNAL_STOP_STOPPED is already set. Don't generate
1981 * group_exit_code in such case.
1982 *
1983 * This is not necessary for SIGNAL_STOP_CONTINUED because
1984 * an intervening stop signal is required to cause two
1985 * continued events regardless of ptrace.
1986 */
1987 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1988 sig->group_exit_code = signr;
1989 else
1990 WARN_ON_ONCE(!current->ptrace);
1991
1992 sig->group_stop_count = 0;
1993
1994 if (task_set_jobctl_pending(current, signr | gstop))
1995 sig->group_stop_count++;
1996
1997 for (t = next_thread(current); t != current;
1998 t = next_thread(t)) {
1999 /*
2000 * Setting state to TASK_STOPPED for a group
2001 * stop is always done with the siglock held,
2002 * so this check has no races.
2003 */
2004 if (!task_is_stopped(t) &&
2005 task_set_jobctl_pending(t, signr | gstop)) {
2006 sig->group_stop_count++;
2007 if (likely(!(t->ptrace & PT_SEIZED)))
2008 signal_wake_up(t, 0);
2009 else
2010 ptrace_trap_notify(t);
2011 }
2012 }
2013 }
2014
2015 if (likely(!current->ptrace)) {
2016 int notify = 0;
2017
2018 /*
2019 * If there are no other threads in the group, or if there
2020 * is a group stop in progress and we are the last to stop,
2021 * report to the parent.
2022 */
2023 if (task_participate_group_stop(current))
2024 notify = CLD_STOPPED;
2025
2026 __set_current_state(TASK_STOPPED);
2027 spin_unlock_irq(¤t->sighand->siglock);
2028
2029 /*
2030 * Notify the parent of the group stop completion. Because
2031 * we're not holding either the siglock or tasklist_lock
2032 * here, ptracer may attach inbetween; however, this is for
2033 * group stop and should always be delivered to the real
2034 * parent of the group leader. The new ptracer will get
2035 * its notification when this task transitions into
2036 * TASK_TRACED.
2037 */
2038 if (notify) {
2039 read_lock(&tasklist_lock);
2040 do_notify_parent_cldstop(current, false, notify);
2041 read_unlock(&tasklist_lock);
2042 }
2043
2044 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2045 schedule();
2046 return true;
2047 } else {
2048 /*
2049 * While ptraced, group stop is handled by STOP trap.
2050 * Schedule it and let the caller deal with it.
2051 */
2052 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2053 return false;
2054 }
2055}
2056
2057/**
2058 * do_jobctl_trap - take care of ptrace jobctl traps
2059 *
2060 * When PT_SEIZED, it's used for both group stop and explicit
2061 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2062 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2063 * the stop signal; otherwise, %SIGTRAP.
2064 *
2065 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2066 * number as exit_code and no siginfo.
2067 *
2068 * CONTEXT:
2069 * Must be called with @current->sighand->siglock held, which may be
2070 * released and re-acquired before returning with intervening sleep.
2071 */
2072static void do_jobctl_trap(void)
2073{
2074 struct signal_struct *signal = current->signal;
2075 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2076
2077 if (current->ptrace & PT_SEIZED) {
2078 if (!signal->group_stop_count &&
2079 !(signal->flags & SIGNAL_STOP_STOPPED))
2080 signr = SIGTRAP;
2081 WARN_ON_ONCE(!signr);
2082 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2083 CLD_STOPPED);
2084 } else {
2085 WARN_ON_ONCE(!signr);
2086 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2087 current->exit_code = 0;
2088 }
2089}
2090
2091static int ptrace_signal(int signr, siginfo_t *info,
2092 struct pt_regs *regs, void *cookie)
2093{
2094 ptrace_signal_deliver(regs, cookie);
2095 /*
2096 * We do not check sig_kernel_stop(signr) but set this marker
2097 * unconditionally because we do not know whether debugger will
2098 * change signr. This flag has no meaning unless we are going
2099 * to stop after return from ptrace_stop(). In this case it will
2100 * be checked in do_signal_stop(), we should only stop if it was
2101 * not cleared by SIGCONT while we were sleeping. See also the
2102 * comment in dequeue_signal().
2103 */
2104 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2105 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2106
2107 /* We're back. Did the debugger cancel the sig? */
2108 signr = current->exit_code;
2109 if (signr == 0)
2110 return signr;
2111
2112 current->exit_code = 0;
2113
2114 /*
2115 * Update the siginfo structure if the signal has
2116 * changed. If the debugger wanted something
2117 * specific in the siginfo structure then it should
2118 * have updated *info via PTRACE_SETSIGINFO.
2119 */
2120 if (signr != info->si_signo) {
2121 info->si_signo = signr;
2122 info->si_errno = 0;
2123 info->si_code = SI_USER;
2124 info->si_pid = task_pid_vnr(current->parent);
2125 info->si_uid = task_uid(current->parent);
2126 }
2127
2128 /* If the (new) signal is now blocked, requeue it. */
2129 if (sigismember(¤t->blocked, signr)) {
2130 specific_send_sig_info(signr, info, current);
2131 signr = 0;
2132 }
2133
2134 return signr;
2135}
2136
2137int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2138 struct pt_regs *regs, void *cookie)
2139{
2140 struct sighand_struct *sighand = current->sighand;
2141 struct signal_struct *signal = current->signal;
2142 int signr;
2143
2144relock:
2145 /*
2146 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2147 * While in TASK_STOPPED, we were considered "frozen enough".
2148 * Now that we woke up, it's crucial if we're supposed to be
2149 * frozen that we freeze now before running anything substantial.
2150 */
2151 try_to_freeze();
2152
2153 spin_lock_irq(&sighand->siglock);
2154 /*
2155 * Every stopped thread goes here after wakeup. Check to see if
2156 * we should notify the parent, prepare_signal(SIGCONT) encodes
2157 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2158 */
2159 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2160 int why;
2161
2162 if (signal->flags & SIGNAL_CLD_CONTINUED)
2163 why = CLD_CONTINUED;
2164 else
2165 why = CLD_STOPPED;
2166
2167 signal->flags &= ~SIGNAL_CLD_MASK;
2168
2169 spin_unlock_irq(&sighand->siglock);
2170
2171 /*
2172 * Notify the parent that we're continuing. This event is
2173 * always per-process and doesn't make whole lot of sense
2174 * for ptracers, who shouldn't consume the state via
2175 * wait(2) either, but, for backward compatibility, notify
2176 * the ptracer of the group leader too unless it's gonna be
2177 * a duplicate.
2178 */
2179 read_lock(&tasklist_lock);
2180 do_notify_parent_cldstop(current, false, why);
2181
2182 if (ptrace_reparented(current->group_leader))
2183 do_notify_parent_cldstop(current->group_leader,
2184 true, why);
2185 read_unlock(&tasklist_lock);
2186
2187 goto relock;
2188 }
2189
2190 for (;;) {
2191 struct k_sigaction *ka;
2192
2193 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2194 do_signal_stop(0))
2195 goto relock;
2196
2197 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2198 do_jobctl_trap();
2199 spin_unlock_irq(&sighand->siglock);
2200 goto relock;
2201 }
2202
2203 signr = dequeue_signal(current, ¤t->blocked, info);
2204
2205 if (!signr)
2206 break; /* will return 0 */
2207
2208 if (unlikely(current->ptrace) && signr != SIGKILL) {
2209 signr = ptrace_signal(signr, info,
2210 regs, cookie);
2211 if (!signr)
2212 continue;
2213 }
2214
2215 ka = &sighand->action[signr-1];
2216
2217 /* Trace actually delivered signals. */
2218 trace_signal_deliver(signr, info, ka);
2219
2220 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2221 continue;
2222 if (ka->sa.sa_handler != SIG_DFL) {
2223 /* Run the handler. */
2224 *return_ka = *ka;
2225
2226 if (ka->sa.sa_flags & SA_ONESHOT)
2227 ka->sa.sa_handler = SIG_DFL;
2228
2229 break; /* will return non-zero "signr" value */
2230 }
2231
2232 /*
2233 * Now we are doing the default action for this signal.
2234 */
2235 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2236 continue;
2237
2238 /*
2239 * Global init gets no signals it doesn't want.
2240 * Container-init gets no signals it doesn't want from same
2241 * container.
2242 *
2243 * Note that if global/container-init sees a sig_kernel_only()
2244 * signal here, the signal must have been generated internally
2245 * or must have come from an ancestor namespace. In either
2246 * case, the signal cannot be dropped.
2247 */
2248 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2249 !sig_kernel_only(signr))
2250 continue;
2251
2252 if (sig_kernel_stop(signr)) {
2253 /*
2254 * The default action is to stop all threads in
2255 * the thread group. The job control signals
2256 * do nothing in an orphaned pgrp, but SIGSTOP
2257 * always works. Note that siglock needs to be
2258 * dropped during the call to is_orphaned_pgrp()
2259 * because of lock ordering with tasklist_lock.
2260 * This allows an intervening SIGCONT to be posted.
2261 * We need to check for that and bail out if necessary.
2262 */
2263 if (signr != SIGSTOP) {
2264 spin_unlock_irq(&sighand->siglock);
2265
2266 /* signals can be posted during this window */
2267
2268 if (is_current_pgrp_orphaned())
2269 goto relock;
2270
2271 spin_lock_irq(&sighand->siglock);
2272 }
2273
2274 if (likely(do_signal_stop(info->si_signo))) {
2275 /* It released the siglock. */
2276 goto relock;
2277 }
2278
2279 /*
2280 * We didn't actually stop, due to a race
2281 * with SIGCONT or something like that.
2282 */
2283 continue;
2284 }
2285
2286 spin_unlock_irq(&sighand->siglock);
2287
2288 /*
2289 * Anything else is fatal, maybe with a core dump.
2290 */
2291 current->flags |= PF_SIGNALED;
2292
2293 if (sig_kernel_coredump(signr)) {
2294 if (print_fatal_signals)
2295 print_fatal_signal(regs, info->si_signo);
2296 /*
2297 * If it was able to dump core, this kills all
2298 * other threads in the group and synchronizes with
2299 * their demise. If we lost the race with another
2300 * thread getting here, it set group_exit_code
2301 * first and our do_group_exit call below will use
2302 * that value and ignore the one we pass it.
2303 */
2304 do_coredump(info->si_signo, info->si_signo, regs);
2305 }
2306
2307 /*
2308 * Death signals, no core dump.
2309 */
2310 do_group_exit(info->si_signo);
2311 /* NOTREACHED */
2312 }
2313 spin_unlock_irq(&sighand->siglock);
2314 return signr;
2315}
2316
2317/*
2318 * It could be that complete_signal() picked us to notify about the
2319 * group-wide signal. Other threads should be notified now to take
2320 * the shared signals in @which since we will not.
2321 */
2322static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2323{
2324 sigset_t retarget;
2325 struct task_struct *t;
2326
2327 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2328 if (sigisemptyset(&retarget))
2329 return;
2330
2331 t = tsk;
2332 while_each_thread(tsk, t) {
2333 if (t->flags & PF_EXITING)
2334 continue;
2335
2336 if (!has_pending_signals(&retarget, &t->blocked))
2337 continue;
2338 /* Remove the signals this thread can handle. */
2339 sigandsets(&retarget, &retarget, &t->blocked);
2340
2341 if (!signal_pending(t))
2342 signal_wake_up(t, 0);
2343
2344 if (sigisemptyset(&retarget))
2345 break;
2346 }
2347}
2348
2349void exit_signals(struct task_struct *tsk)
2350{
2351 int group_stop = 0;
2352 sigset_t unblocked;
2353
2354 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2355 tsk->flags |= PF_EXITING;
2356 return;
2357 }
2358
2359 spin_lock_irq(&tsk->sighand->siglock);
2360 /*
2361 * From now this task is not visible for group-wide signals,
2362 * see wants_signal(), do_signal_stop().
2363 */
2364 tsk->flags |= PF_EXITING;
2365 if (!signal_pending(tsk))
2366 goto out;
2367
2368 unblocked = tsk->blocked;
2369 signotset(&unblocked);
2370 retarget_shared_pending(tsk, &unblocked);
2371
2372 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2373 task_participate_group_stop(tsk))
2374 group_stop = CLD_STOPPED;
2375out:
2376 spin_unlock_irq(&tsk->sighand->siglock);
2377
2378 /*
2379 * If group stop has completed, deliver the notification. This
2380 * should always go to the real parent of the group leader.
2381 */
2382 if (unlikely(group_stop)) {
2383 read_lock(&tasklist_lock);
2384 do_notify_parent_cldstop(tsk, false, group_stop);
2385 read_unlock(&tasklist_lock);
2386 }
2387}
2388
2389EXPORT_SYMBOL(recalc_sigpending);
2390EXPORT_SYMBOL_GPL(dequeue_signal);
2391EXPORT_SYMBOL(flush_signals);
2392EXPORT_SYMBOL(force_sig);
2393EXPORT_SYMBOL(send_sig);
2394EXPORT_SYMBOL(send_sig_info);
2395EXPORT_SYMBOL(sigprocmask);
2396EXPORT_SYMBOL(block_all_signals);
2397EXPORT_SYMBOL(unblock_all_signals);
2398
2399
2400/*
2401 * System call entry points.
2402 */
2403
2404/**
2405 * sys_restart_syscall - restart a system call
2406 */
2407SYSCALL_DEFINE0(restart_syscall)
2408{
2409 struct restart_block *restart = ¤t_thread_info()->restart_block;
2410 return restart->fn(restart);
2411}
2412
2413long do_no_restart_syscall(struct restart_block *param)
2414{
2415 return -EINTR;
2416}
2417
2418static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2419{
2420 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2421 sigset_t newblocked;
2422 /* A set of now blocked but previously unblocked signals. */
2423 sigandnsets(&newblocked, newset, ¤t->blocked);
2424 retarget_shared_pending(tsk, &newblocked);
2425 }
2426 tsk->blocked = *newset;
2427 recalc_sigpending();
2428}
2429
2430/**
2431 * set_current_blocked - change current->blocked mask
2432 * @newset: new mask
2433 *
2434 * It is wrong to change ->blocked directly, this helper should be used
2435 * to ensure the process can't miss a shared signal we are going to block.
2436 */
2437void set_current_blocked(const sigset_t *newset)
2438{
2439 struct task_struct *tsk = current;
2440
2441 spin_lock_irq(&tsk->sighand->siglock);
2442 __set_task_blocked(tsk, newset);
2443 spin_unlock_irq(&tsk->sighand->siglock);
2444}
2445
2446/*
2447 * This is also useful for kernel threads that want to temporarily
2448 * (or permanently) block certain signals.
2449 *
2450 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2451 * interface happily blocks "unblockable" signals like SIGKILL
2452 * and friends.
2453 */
2454int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2455{
2456 struct task_struct *tsk = current;
2457 sigset_t newset;
2458
2459 /* Lockless, only current can change ->blocked, never from irq */
2460 if (oldset)
2461 *oldset = tsk->blocked;
2462
2463 switch (how) {
2464 case SIG_BLOCK:
2465 sigorsets(&newset, &tsk->blocked, set);
2466 break;
2467 case SIG_UNBLOCK:
2468 sigandnsets(&newset, &tsk->blocked, set);
2469 break;
2470 case SIG_SETMASK:
2471 newset = *set;
2472 break;
2473 default:
2474 return -EINVAL;
2475 }
2476
2477 set_current_blocked(&newset);
2478 return 0;
2479}
2480
2481/**
2482 * sys_rt_sigprocmask - change the list of currently blocked signals
2483 * @how: whether to add, remove, or set signals
2484 * @nset: stores pending signals
2485 * @oset: previous value of signal mask if non-null
2486 * @sigsetsize: size of sigset_t type
2487 */
2488SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2489 sigset_t __user *, oset, size_t, sigsetsize)
2490{
2491 sigset_t old_set, new_set;
2492 int error;
2493
2494 /* XXX: Don't preclude handling different sized sigset_t's. */
2495 if (sigsetsize != sizeof(sigset_t))
2496 return -EINVAL;
2497
2498 old_set = current->blocked;
2499
2500 if (nset) {
2501 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2502 return -EFAULT;
2503 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2504
2505 error = sigprocmask(how, &new_set, NULL);
2506 if (error)
2507 return error;
2508 }
2509
2510 if (oset) {
2511 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2512 return -EFAULT;
2513 }
2514
2515 return 0;
2516}
2517
2518long do_sigpending(void __user *set, unsigned long sigsetsize)
2519{
2520 long error = -EINVAL;
2521 sigset_t pending;
2522
2523 if (sigsetsize > sizeof(sigset_t))
2524 goto out;
2525
2526 spin_lock_irq(¤t->sighand->siglock);
2527 sigorsets(&pending, ¤t->pending.signal,
2528 ¤t->signal->shared_pending.signal);
2529 spin_unlock_irq(¤t->sighand->siglock);
2530
2531 /* Outside the lock because only this thread touches it. */
2532 sigandsets(&pending, ¤t->blocked, &pending);
2533
2534 error = -EFAULT;
2535 if (!copy_to_user(set, &pending, sigsetsize))
2536 error = 0;
2537
2538out:
2539 return error;
2540}
2541
2542/**
2543 * sys_rt_sigpending - examine a pending signal that has been raised
2544 * while blocked
2545 * @set: stores pending signals
2546 * @sigsetsize: size of sigset_t type or larger
2547 */
2548SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2549{
2550 return do_sigpending(set, sigsetsize);
2551}
2552
2553#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2554
2555int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2556{
2557 int err;
2558
2559 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2560 return -EFAULT;
2561 if (from->si_code < 0)
2562 return __copy_to_user(to, from, sizeof(siginfo_t))
2563 ? -EFAULT : 0;
2564 /*
2565 * If you change siginfo_t structure, please be sure
2566 * this code is fixed accordingly.
2567 * Please remember to update the signalfd_copyinfo() function
2568 * inside fs/signalfd.c too, in case siginfo_t changes.
2569 * It should never copy any pad contained in the structure
2570 * to avoid security leaks, but must copy the generic
2571 * 3 ints plus the relevant union member.
2572 */
2573 err = __put_user(from->si_signo, &to->si_signo);
2574 err |= __put_user(from->si_errno, &to->si_errno);
2575 err |= __put_user((short)from->si_code, &to->si_code);
2576 switch (from->si_code & __SI_MASK) {
2577 case __SI_KILL:
2578 err |= __put_user(from->si_pid, &to->si_pid);
2579 err |= __put_user(from->si_uid, &to->si_uid);
2580 break;
2581 case __SI_TIMER:
2582 err |= __put_user(from->si_tid, &to->si_tid);
2583 err |= __put_user(from->si_overrun, &to->si_overrun);
2584 err |= __put_user(from->si_ptr, &to->si_ptr);
2585 break;
2586 case __SI_POLL:
2587 err |= __put_user(from->si_band, &to->si_band);
2588 err |= __put_user(from->si_fd, &to->si_fd);
2589 break;
2590 case __SI_FAULT:
2591 err |= __put_user(from->si_addr, &to->si_addr);
2592#ifdef __ARCH_SI_TRAPNO
2593 err |= __put_user(from->si_trapno, &to->si_trapno);
2594#endif
2595#ifdef BUS_MCEERR_AO
2596 /*
2597 * Other callers might not initialize the si_lsb field,
2598 * so check explicitly for the right codes here.
2599 */
2600 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2601 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2602#endif
2603 break;
2604 case __SI_CHLD:
2605 err |= __put_user(from->si_pid, &to->si_pid);
2606 err |= __put_user(from->si_uid, &to->si_uid);
2607 err |= __put_user(from->si_status, &to->si_status);
2608 err |= __put_user(from->si_utime, &to->si_utime);
2609 err |= __put_user(from->si_stime, &to->si_stime);
2610 break;
2611 case __SI_RT: /* This is not generated by the kernel as of now. */
2612 case __SI_MESGQ: /* But this is */
2613 err |= __put_user(from->si_pid, &to->si_pid);
2614 err |= __put_user(from->si_uid, &to->si_uid);
2615 err |= __put_user(from->si_ptr, &to->si_ptr);
2616 break;
2617 default: /* this is just in case for now ... */
2618 err |= __put_user(from->si_pid, &to->si_pid);
2619 err |= __put_user(from->si_uid, &to->si_uid);
2620 break;
2621 }
2622 return err;
2623}
2624
2625#endif
2626
2627/**
2628 * do_sigtimedwait - wait for queued signals specified in @which
2629 * @which: queued signals to wait for
2630 * @info: if non-null, the signal's siginfo is returned here
2631 * @ts: upper bound on process time suspension
2632 */
2633int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2634 const struct timespec *ts)
2635{
2636 struct task_struct *tsk = current;
2637 long timeout = MAX_SCHEDULE_TIMEOUT;
2638 sigset_t mask = *which;
2639 int sig;
2640
2641 if (ts) {
2642 if (!timespec_valid(ts))
2643 return -EINVAL;
2644 timeout = timespec_to_jiffies(ts);
2645 /*
2646 * We can be close to the next tick, add another one
2647 * to ensure we will wait at least the time asked for.
2648 */
2649 if (ts->tv_sec || ts->tv_nsec)
2650 timeout++;
2651 }
2652
2653 /*
2654 * Invert the set of allowed signals to get those we want to block.
2655 */
2656 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2657 signotset(&mask);
2658
2659 spin_lock_irq(&tsk->sighand->siglock);
2660 sig = dequeue_signal(tsk, &mask, info);
2661 if (!sig && timeout) {
2662 /*
2663 * None ready, temporarily unblock those we're interested
2664 * while we are sleeping in so that we'll be awakened when
2665 * they arrive. Unblocking is always fine, we can avoid
2666 * set_current_blocked().
2667 */
2668 tsk->real_blocked = tsk->blocked;
2669 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2670 recalc_sigpending();
2671 spin_unlock_irq(&tsk->sighand->siglock);
2672
2673 timeout = schedule_timeout_interruptible(timeout);
2674
2675 spin_lock_irq(&tsk->sighand->siglock);
2676 __set_task_blocked(tsk, &tsk->real_blocked);
2677 siginitset(&tsk->real_blocked, 0);
2678 sig = dequeue_signal(tsk, &mask, info);
2679 }
2680 spin_unlock_irq(&tsk->sighand->siglock);
2681
2682 if (sig)
2683 return sig;
2684 return timeout ? -EINTR : -EAGAIN;
2685}
2686
2687/**
2688 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2689 * in @uthese
2690 * @uthese: queued signals to wait for
2691 * @uinfo: if non-null, the signal's siginfo is returned here
2692 * @uts: upper bound on process time suspension
2693 * @sigsetsize: size of sigset_t type
2694 */
2695SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2696 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2697 size_t, sigsetsize)
2698{
2699 sigset_t these;
2700 struct timespec ts;
2701 siginfo_t info;
2702 int ret;
2703
2704 /* XXX: Don't preclude handling different sized sigset_t's. */
2705 if (sigsetsize != sizeof(sigset_t))
2706 return -EINVAL;
2707
2708 if (copy_from_user(&these, uthese, sizeof(these)))
2709 return -EFAULT;
2710
2711 if (uts) {
2712 if (copy_from_user(&ts, uts, sizeof(ts)))
2713 return -EFAULT;
2714 }
2715
2716 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2717
2718 if (ret > 0 && uinfo) {
2719 if (copy_siginfo_to_user(uinfo, &info))
2720 ret = -EFAULT;
2721 }
2722
2723 return ret;
2724}
2725
2726/**
2727 * sys_kill - send a signal to a process
2728 * @pid: the PID of the process
2729 * @sig: signal to be sent
2730 */
2731SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2732{
2733 struct siginfo info;
2734
2735 info.si_signo = sig;
2736 info.si_errno = 0;
2737 info.si_code = SI_USER;
2738 info.si_pid = task_tgid_vnr(current);
2739 info.si_uid = current_uid();
2740
2741 return kill_something_info(sig, &info, pid);
2742}
2743
2744static int
2745do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2746{
2747 struct task_struct *p;
2748 int error = -ESRCH;
2749
2750 rcu_read_lock();
2751 p = find_task_by_vpid(pid);
2752 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2753 error = check_kill_permission(sig, info, p);
2754 /*
2755 * The null signal is a permissions and process existence
2756 * probe. No signal is actually delivered.
2757 */
2758 if (!error && sig) {
2759 error = do_send_sig_info(sig, info, p, false);
2760 /*
2761 * If lock_task_sighand() failed we pretend the task
2762 * dies after receiving the signal. The window is tiny,
2763 * and the signal is private anyway.
2764 */
2765 if (unlikely(error == -ESRCH))
2766 error = 0;
2767 }
2768 }
2769 rcu_read_unlock();
2770
2771 return error;
2772}
2773
2774static int do_tkill(pid_t tgid, pid_t pid, int sig)
2775{
2776 struct siginfo info;
2777
2778 info.si_signo = sig;
2779 info.si_errno = 0;
2780 info.si_code = SI_TKILL;
2781 info.si_pid = task_tgid_vnr(current);
2782 info.si_uid = current_uid();
2783
2784 return do_send_specific(tgid, pid, sig, &info);
2785}
2786
2787/**
2788 * sys_tgkill - send signal to one specific thread
2789 * @tgid: the thread group ID of the thread
2790 * @pid: the PID of the thread
2791 * @sig: signal to be sent
2792 *
2793 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2794 * exists but it's not belonging to the target process anymore. This
2795 * method solves the problem of threads exiting and PIDs getting reused.
2796 */
2797SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2798{
2799 /* This is only valid for single tasks */
2800 if (pid <= 0 || tgid <= 0)
2801 return -EINVAL;
2802
2803 return do_tkill(tgid, pid, sig);
2804}
2805
2806/**
2807 * sys_tkill - send signal to one specific task
2808 * @pid: the PID of the task
2809 * @sig: signal to be sent
2810 *
2811 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2812 */
2813SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2814{
2815 /* This is only valid for single tasks */
2816 if (pid <= 0)
2817 return -EINVAL;
2818
2819 return do_tkill(0, pid, sig);
2820}
2821
2822/**
2823 * sys_rt_sigqueueinfo - send signal information to a signal
2824 * @pid: the PID of the thread
2825 * @sig: signal to be sent
2826 * @uinfo: signal info to be sent
2827 */
2828SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2829 siginfo_t __user *, uinfo)
2830{
2831 siginfo_t info;
2832
2833 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2834 return -EFAULT;
2835
2836 /* Not even root can pretend to send signals from the kernel.
2837 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2838 */
2839 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2840 /* We used to allow any < 0 si_code */
2841 WARN_ON_ONCE(info.si_code < 0);
2842 return -EPERM;
2843 }
2844 info.si_signo = sig;
2845
2846 /* POSIX.1b doesn't mention process groups. */
2847 return kill_proc_info(sig, &info, pid);
2848}
2849
2850long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2851{
2852 /* This is only valid for single tasks */
2853 if (pid <= 0 || tgid <= 0)
2854 return -EINVAL;
2855
2856 /* Not even root can pretend to send signals from the kernel.
2857 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2858 */
2859 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2860 /* We used to allow any < 0 si_code */
2861 WARN_ON_ONCE(info->si_code < 0);
2862 return -EPERM;
2863 }
2864 info->si_signo = sig;
2865
2866 return do_send_specific(tgid, pid, sig, info);
2867}
2868
2869SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2870 siginfo_t __user *, uinfo)
2871{
2872 siginfo_t info;
2873
2874 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2875 return -EFAULT;
2876
2877 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2878}
2879
2880int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2881{
2882 struct task_struct *t = current;
2883 struct k_sigaction *k;
2884 sigset_t mask;
2885
2886 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2887 return -EINVAL;
2888
2889 k = &t->sighand->action[sig-1];
2890
2891 spin_lock_irq(¤t->sighand->siglock);
2892 if (oact)
2893 *oact = *k;
2894
2895 if (act) {
2896 sigdelsetmask(&act->sa.sa_mask,
2897 sigmask(SIGKILL) | sigmask(SIGSTOP));
2898 *k = *act;
2899 /*
2900 * POSIX 3.3.1.3:
2901 * "Setting a signal action to SIG_IGN for a signal that is
2902 * pending shall cause the pending signal to be discarded,
2903 * whether or not it is blocked."
2904 *
2905 * "Setting a signal action to SIG_DFL for a signal that is
2906 * pending and whose default action is to ignore the signal
2907 * (for example, SIGCHLD), shall cause the pending signal to
2908 * be discarded, whether or not it is blocked"
2909 */
2910 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2911 sigemptyset(&mask);
2912 sigaddset(&mask, sig);
2913 rm_from_queue_full(&mask, &t->signal->shared_pending);
2914 do {
2915 rm_from_queue_full(&mask, &t->pending);
2916 t = next_thread(t);
2917 } while (t != current);
2918 }
2919 }
2920
2921 spin_unlock_irq(¤t->sighand->siglock);
2922 return 0;
2923}
2924
2925int
2926do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2927{
2928 stack_t oss;
2929 int error;
2930
2931 oss.ss_sp = (void __user *) current->sas_ss_sp;
2932 oss.ss_size = current->sas_ss_size;
2933 oss.ss_flags = sas_ss_flags(sp);
2934
2935 if (uss) {
2936 void __user *ss_sp;
2937 size_t ss_size;
2938 int ss_flags;
2939
2940 error = -EFAULT;
2941 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
2942 goto out;
2943 error = __get_user(ss_sp, &uss->ss_sp) |
2944 __get_user(ss_flags, &uss->ss_flags) |
2945 __get_user(ss_size, &uss->ss_size);
2946 if (error)
2947 goto out;
2948
2949 error = -EPERM;
2950 if (on_sig_stack(sp))
2951 goto out;
2952
2953 error = -EINVAL;
2954 /*
2955 * Note - this code used to test ss_flags incorrectly:
2956 * old code may have been written using ss_flags==0
2957 * to mean ss_flags==SS_ONSTACK (as this was the only
2958 * way that worked) - this fix preserves that older
2959 * mechanism.
2960 */
2961 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2962 goto out;
2963
2964 if (ss_flags == SS_DISABLE) {
2965 ss_size = 0;
2966 ss_sp = NULL;
2967 } else {
2968 error = -ENOMEM;
2969 if (ss_size < MINSIGSTKSZ)
2970 goto out;
2971 }
2972
2973 current->sas_ss_sp = (unsigned long) ss_sp;
2974 current->sas_ss_size = ss_size;
2975 }
2976
2977 error = 0;
2978 if (uoss) {
2979 error = -EFAULT;
2980 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
2981 goto out;
2982 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
2983 __put_user(oss.ss_size, &uoss->ss_size) |
2984 __put_user(oss.ss_flags, &uoss->ss_flags);
2985 }
2986
2987out:
2988 return error;
2989}
2990
2991#ifdef __ARCH_WANT_SYS_SIGPENDING
2992
2993/**
2994 * sys_sigpending - examine pending signals
2995 * @set: where mask of pending signal is returned
2996 */
2997SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
2998{
2999 return do_sigpending(set, sizeof(*set));
3000}
3001
3002#endif
3003
3004#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3005/**
3006 * sys_sigprocmask - examine and change blocked signals
3007 * @how: whether to add, remove, or set signals
3008 * @nset: signals to add or remove (if non-null)
3009 * @oset: previous value of signal mask if non-null
3010 *
3011 * Some platforms have their own version with special arguments;
3012 * others support only sys_rt_sigprocmask.
3013 */
3014
3015SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3016 old_sigset_t __user *, oset)
3017{
3018 old_sigset_t old_set, new_set;
3019 sigset_t new_blocked;
3020
3021 old_set = current->blocked.sig[0];
3022
3023 if (nset) {
3024 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3025 return -EFAULT;
3026 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3027
3028 new_blocked = current->blocked;
3029
3030 switch (how) {
3031 case SIG_BLOCK:
3032 sigaddsetmask(&new_blocked, new_set);
3033 break;
3034 case SIG_UNBLOCK:
3035 sigdelsetmask(&new_blocked, new_set);
3036 break;
3037 case SIG_SETMASK:
3038 new_blocked.sig[0] = new_set;
3039 break;
3040 default:
3041 return -EINVAL;
3042 }
3043
3044 set_current_blocked(&new_blocked);
3045 }
3046
3047 if (oset) {
3048 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3049 return -EFAULT;
3050 }
3051
3052 return 0;
3053}
3054#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3055
3056#ifdef __ARCH_WANT_SYS_RT_SIGACTION
3057/**
3058 * sys_rt_sigaction - alter an action taken by a process
3059 * @sig: signal to be sent
3060 * @act: new sigaction
3061 * @oact: used to save the previous sigaction
3062 * @sigsetsize: size of sigset_t type
3063 */
3064SYSCALL_DEFINE4(rt_sigaction, int, sig,
3065 const struct sigaction __user *, act,
3066 struct sigaction __user *, oact,
3067 size_t, sigsetsize)
3068{
3069 struct k_sigaction new_sa, old_sa;
3070 int ret = -EINVAL;
3071
3072 /* XXX: Don't preclude handling different sized sigset_t's. */
3073 if (sigsetsize != sizeof(sigset_t))
3074 goto out;
3075
3076 if (act) {
3077 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3078 return -EFAULT;
3079 }
3080
3081 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3082
3083 if (!ret && oact) {
3084 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3085 return -EFAULT;
3086 }
3087out:
3088 return ret;
3089}
3090#endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3091
3092#ifdef __ARCH_WANT_SYS_SGETMASK
3093
3094/*
3095 * For backwards compatibility. Functionality superseded by sigprocmask.
3096 */
3097SYSCALL_DEFINE0(sgetmask)
3098{
3099 /* SMP safe */
3100 return current->blocked.sig[0];
3101}
3102
3103SYSCALL_DEFINE1(ssetmask, int, newmask)
3104{
3105 int old = current->blocked.sig[0];
3106 sigset_t newset;
3107
3108 siginitset(&newset, newmask & ~(sigmask(SIGKILL) | sigmask(SIGSTOP)));
3109 set_current_blocked(&newset);
3110
3111 return old;
3112}
3113#endif /* __ARCH_WANT_SGETMASK */
3114
3115#ifdef __ARCH_WANT_SYS_SIGNAL
3116/*
3117 * For backwards compatibility. Functionality superseded by sigaction.
3118 */
3119SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3120{
3121 struct k_sigaction new_sa, old_sa;
3122 int ret;
3123
3124 new_sa.sa.sa_handler = handler;
3125 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3126 sigemptyset(&new_sa.sa.sa_mask);
3127
3128 ret = do_sigaction(sig, &new_sa, &old_sa);
3129
3130 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3131}
3132#endif /* __ARCH_WANT_SYS_SIGNAL */
3133
3134#ifdef __ARCH_WANT_SYS_PAUSE
3135
3136SYSCALL_DEFINE0(pause)
3137{
3138 while (!signal_pending(current)) {
3139 current->state = TASK_INTERRUPTIBLE;
3140 schedule();
3141 }
3142 return -ERESTARTNOHAND;
3143}
3144
3145#endif
3146
3147#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3148/**
3149 * sys_rt_sigsuspend - replace the signal mask for a value with the
3150 * @unewset value until a signal is received
3151 * @unewset: new signal mask value
3152 * @sigsetsize: size of sigset_t type
3153 */
3154SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3155{
3156 sigset_t newset;
3157
3158 /* XXX: Don't preclude handling different sized sigset_t's. */
3159 if (sigsetsize != sizeof(sigset_t))
3160 return -EINVAL;
3161
3162 if (copy_from_user(&newset, unewset, sizeof(newset)))
3163 return -EFAULT;
3164 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
3165
3166 current->saved_sigmask = current->blocked;
3167 set_current_blocked(&newset);
3168
3169 current->state = TASK_INTERRUPTIBLE;
3170 schedule();
3171 set_restore_sigmask();
3172 return -ERESTARTNOHAND;
3173}
3174#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3175
3176__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3177{
3178 return NULL;
3179}
3180
3181void __init signals_init(void)
3182{
3183 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3184}
3185
3186#ifdef CONFIG_KGDB_KDB
3187#include <linux/kdb.h>
3188/*
3189 * kdb_send_sig_info - Allows kdb to send signals without exposing
3190 * signal internals. This function checks if the required locks are
3191 * available before calling the main signal code, to avoid kdb
3192 * deadlocks.
3193 */
3194void
3195kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3196{
3197 static struct task_struct *kdb_prev_t;
3198 int sig, new_t;
3199 if (!spin_trylock(&t->sighand->siglock)) {
3200 kdb_printf("Can't do kill command now.\n"
3201 "The sigmask lock is held somewhere else in "
3202 "kernel, try again later\n");
3203 return;
3204 }
3205 spin_unlock(&t->sighand->siglock);
3206 new_t = kdb_prev_t != t;
3207 kdb_prev_t = t;
3208 if (t->state != TASK_RUNNING && new_t) {
3209 kdb_printf("Process is not RUNNING, sending a signal from "
3210 "kdb risks deadlock\n"
3211 "on the run queue locks. "
3212 "The signal has _not_ been sent.\n"
3213 "Reissue the kill command if you want to risk "
3214 "the deadlock.\n");
3215 return;
3216 }
3217 sig = info->si_signo;
3218 if (send_sig_info(sig, info, t))
3219 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3220 sig, t->pid);
3221 else
3222 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3223}
3224#endif /* CONFIG_KGDB_KDB */