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