Loading...
1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/coredump.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/ptrace.h>
24#include <linux/signal.h>
25#include <linux/signalfd.h>
26#include <linux/ratelimit.h>
27#include <linux/tracehook.h>
28#include <linux/capability.h>
29#include <linux/freezer.h>
30#include <linux/pid_namespace.h>
31#include <linux/nsproxy.h>
32#include <linux/user_namespace.h>
33#include <linux/uprobes.h>
34#include <linux/compat.h>
35#include <linux/cn_proc.h>
36#include <linux/compiler.h>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <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/mm.h>
17#include <linux/sched/user.h>
18#include <linux/sched/debug.h>
19#include <linux/sched/task.h>
20#include <linux/sched/task_stack.h>
21#include <linux/sched/cputime.h>
22#include <linux/fs.h>
23#include <linux/tty.h>
24#include <linux/binfmts.h>
25#include <linux/coredump.h>
26#include <linux/security.h>
27#include <linux/syscalls.h>
28#include <linux/ptrace.h>
29#include <linux/signal.h>
30#include <linux/signalfd.h>
31#include <linux/ratelimit.h>
32#include <linux/tracehook.h>
33#include <linux/capability.h>
34#include <linux/freezer.h>
35#include <linux/pid_namespace.h>
36#include <linux/nsproxy.h>
37#include <linux/user_namespace.h>
38#include <linux/uprobes.h>
39#include <linux/compat.h>
40#include <linux/cn_proc.h>
41#include <linux/compiler.h>
42#include <linux/posix-timers.h>
43#include <linux/livepatch.h>
44
45#define CREATE_TRACE_POINTS
46#include <trace/events/signal.h>
47
48#include <asm/param.h>
49#include <linux/uaccess.h>
50#include <asm/unistd.h>
51#include <asm/siginfo.h>
52#include <asm/cacheflush.h>
53#include "audit.h" /* audit_signal_info() */
54
55/*
56 * SLAB caches for signal bits.
57 */
58
59static struct kmem_cache *sigqueue_cachep;
60
61int print_fatal_signals __read_mostly;
62
63static void __user *sig_handler(struct task_struct *t, int sig)
64{
65 return t->sighand->action[sig - 1].sa.sa_handler;
66}
67
68static int sig_handler_ignored(void __user *handler, int sig)
69{
70 /* Is it explicitly or implicitly ignored? */
71 return handler == SIG_IGN ||
72 (handler == SIG_DFL && sig_kernel_ignore(sig));
73}
74
75static int sig_task_ignored(struct task_struct *t, int sig, bool force)
76{
77 void __user *handler;
78
79 handler = sig_handler(t, sig);
80
81 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
82 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
83 return 1;
84
85 return sig_handler_ignored(handler, sig);
86}
87
88static int sig_ignored(struct task_struct *t, int sig, bool force)
89{
90 /*
91 * Blocked signals are never ignored, since the
92 * signal handler may change by the time it is
93 * unblocked.
94 */
95 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
96 return 0;
97
98 /*
99 * Tracers may want to know about even ignored signal unless it
100 * is SIGKILL which can't be reported anyway but can be ignored
101 * by SIGNAL_UNKILLABLE task.
102 */
103 if (t->ptrace && sig != SIGKILL)
104 return 0;
105
106 return sig_task_ignored(t, sig, force);
107}
108
109/*
110 * Re-calculate pending state from the set of locally pending
111 * signals, globally pending signals, and blocked signals.
112 */
113static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
114{
115 unsigned long ready;
116 long i;
117
118 switch (_NSIG_WORDS) {
119 default:
120 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
121 ready |= signal->sig[i] &~ blocked->sig[i];
122 break;
123
124 case 4: ready = signal->sig[3] &~ blocked->sig[3];
125 ready |= signal->sig[2] &~ blocked->sig[2];
126 ready |= signal->sig[1] &~ blocked->sig[1];
127 ready |= signal->sig[0] &~ blocked->sig[0];
128 break;
129
130 case 2: ready = signal->sig[1] &~ blocked->sig[1];
131 ready |= signal->sig[0] &~ blocked->sig[0];
132 break;
133
134 case 1: ready = signal->sig[0] &~ blocked->sig[0];
135 }
136 return ready != 0;
137}
138
139#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
140
141static int recalc_sigpending_tsk(struct task_struct *t)
142{
143 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
144 PENDING(&t->pending, &t->blocked) ||
145 PENDING(&t->signal->shared_pending, &t->blocked)) {
146 set_tsk_thread_flag(t, TIF_SIGPENDING);
147 return 1;
148 }
149 /*
150 * We must never clear the flag in another thread, or in current
151 * when it's possible the current syscall is returning -ERESTART*.
152 * So we don't clear it here, and only callers who know they should do.
153 */
154 return 0;
155}
156
157/*
158 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
159 * This is superfluous when called on current, the wakeup is a harmless no-op.
160 */
161void recalc_sigpending_and_wake(struct task_struct *t)
162{
163 if (recalc_sigpending_tsk(t))
164 signal_wake_up(t, 0);
165}
166
167void recalc_sigpending(void)
168{
169 if (!recalc_sigpending_tsk(current) && !freezing(current) &&
170 !klp_patch_pending(current))
171 clear_thread_flag(TIF_SIGPENDING);
172
173}
174
175/* Given the mask, find the first available signal that should be serviced. */
176
177#define SYNCHRONOUS_MASK \
178 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
179 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
180
181int next_signal(struct sigpending *pending, sigset_t *mask)
182{
183 unsigned long i, *s, *m, x;
184 int sig = 0;
185
186 s = pending->signal.sig;
187 m = mask->sig;
188
189 /*
190 * Handle the first word specially: it contains the
191 * synchronous signals that need to be dequeued first.
192 */
193 x = *s &~ *m;
194 if (x) {
195 if (x & SYNCHRONOUS_MASK)
196 x &= SYNCHRONOUS_MASK;
197 sig = ffz(~x) + 1;
198 return sig;
199 }
200
201 switch (_NSIG_WORDS) {
202 default:
203 for (i = 1; i < _NSIG_WORDS; ++i) {
204 x = *++s &~ *++m;
205 if (!x)
206 continue;
207 sig = ffz(~x) + i*_NSIG_BPW + 1;
208 break;
209 }
210 break;
211
212 case 2:
213 x = s[1] &~ m[1];
214 if (!x)
215 break;
216 sig = ffz(~x) + _NSIG_BPW + 1;
217 break;
218
219 case 1:
220 /* Nothing to do */
221 break;
222 }
223
224 return sig;
225}
226
227static inline void print_dropped_signal(int sig)
228{
229 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
230
231 if (!print_fatal_signals)
232 return;
233
234 if (!__ratelimit(&ratelimit_state))
235 return;
236
237 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
238 current->comm, current->pid, sig);
239}
240
241/**
242 * task_set_jobctl_pending - set jobctl pending bits
243 * @task: target task
244 * @mask: pending bits to set
245 *
246 * Clear @mask from @task->jobctl. @mask must be subset of
247 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
248 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
249 * cleared. If @task is already being killed or exiting, this function
250 * becomes noop.
251 *
252 * CONTEXT:
253 * Must be called with @task->sighand->siglock held.
254 *
255 * RETURNS:
256 * %true if @mask is set, %false if made noop because @task was dying.
257 */
258bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
259{
260 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
261 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
262 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
263
264 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
265 return false;
266
267 if (mask & JOBCTL_STOP_SIGMASK)
268 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
269
270 task->jobctl |= mask;
271 return true;
272}
273
274/**
275 * task_clear_jobctl_trapping - clear jobctl trapping bit
276 * @task: target task
277 *
278 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
279 * Clear it and wake up the ptracer. Note that we don't need any further
280 * locking. @task->siglock guarantees that @task->parent points to the
281 * ptracer.
282 *
283 * CONTEXT:
284 * Must be called with @task->sighand->siglock held.
285 */
286void task_clear_jobctl_trapping(struct task_struct *task)
287{
288 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
289 task->jobctl &= ~JOBCTL_TRAPPING;
290 smp_mb(); /* advised by wake_up_bit() */
291 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
292 }
293}
294
295/**
296 * task_clear_jobctl_pending - clear jobctl pending bits
297 * @task: target task
298 * @mask: pending bits to clear
299 *
300 * Clear @mask from @task->jobctl. @mask must be subset of
301 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
302 * STOP bits are cleared together.
303 *
304 * If clearing of @mask leaves no stop or trap pending, this function calls
305 * task_clear_jobctl_trapping().
306 *
307 * CONTEXT:
308 * Must be called with @task->sighand->siglock held.
309 */
310void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
311{
312 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
313
314 if (mask & JOBCTL_STOP_PENDING)
315 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
316
317 task->jobctl &= ~mask;
318
319 if (!(task->jobctl & JOBCTL_PENDING_MASK))
320 task_clear_jobctl_trapping(task);
321}
322
323/**
324 * task_participate_group_stop - participate in a group stop
325 * @task: task participating in a group stop
326 *
327 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
328 * Group stop states are cleared and the group stop count is consumed if
329 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
330 * stop, the appropriate %SIGNAL_* flags are set.
331 *
332 * CONTEXT:
333 * Must be called with @task->sighand->siglock held.
334 *
335 * RETURNS:
336 * %true if group stop completion should be notified to the parent, %false
337 * otherwise.
338 */
339static bool task_participate_group_stop(struct task_struct *task)
340{
341 struct signal_struct *sig = task->signal;
342 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
343
344 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
345
346 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
347
348 if (!consume)
349 return false;
350
351 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
352 sig->group_stop_count--;
353
354 /*
355 * Tell the caller to notify completion iff we are entering into a
356 * fresh group stop. Read comment in do_signal_stop() for details.
357 */
358 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
359 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
360 return true;
361 }
362 return false;
363}
364
365/*
366 * allocate a new signal queue record
367 * - this may be called without locks if and only if t == current, otherwise an
368 * appropriate lock must be held to stop the target task from exiting
369 */
370static struct sigqueue *
371__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
372{
373 struct sigqueue *q = NULL;
374 struct user_struct *user;
375
376 /*
377 * Protect access to @t credentials. This can go away when all
378 * callers hold rcu read lock.
379 */
380 rcu_read_lock();
381 user = get_uid(__task_cred(t)->user);
382 atomic_inc(&user->sigpending);
383 rcu_read_unlock();
384
385 if (override_rlimit ||
386 atomic_read(&user->sigpending) <=
387 task_rlimit(t, RLIMIT_SIGPENDING)) {
388 q = kmem_cache_alloc(sigqueue_cachep, flags);
389 } else {
390 print_dropped_signal(sig);
391 }
392
393 if (unlikely(q == NULL)) {
394 atomic_dec(&user->sigpending);
395 free_uid(user);
396 } else {
397 INIT_LIST_HEAD(&q->list);
398 q->flags = 0;
399 q->user = user;
400 }
401
402 return q;
403}
404
405static void __sigqueue_free(struct sigqueue *q)
406{
407 if (q->flags & SIGQUEUE_PREALLOC)
408 return;
409 atomic_dec(&q->user->sigpending);
410 free_uid(q->user);
411 kmem_cache_free(sigqueue_cachep, q);
412}
413
414void flush_sigqueue(struct sigpending *queue)
415{
416 struct sigqueue *q;
417
418 sigemptyset(&queue->signal);
419 while (!list_empty(&queue->list)) {
420 q = list_entry(queue->list.next, struct sigqueue , list);
421 list_del_init(&q->list);
422 __sigqueue_free(q);
423 }
424}
425
426/*
427 * Flush all pending signals for this kthread.
428 */
429void flush_signals(struct task_struct *t)
430{
431 unsigned long flags;
432
433 spin_lock_irqsave(&t->sighand->siglock, flags);
434 clear_tsk_thread_flag(t, TIF_SIGPENDING);
435 flush_sigqueue(&t->pending);
436 flush_sigqueue(&t->signal->shared_pending);
437 spin_unlock_irqrestore(&t->sighand->siglock, flags);
438}
439
440#ifdef CONFIG_POSIX_TIMERS
441static void __flush_itimer_signals(struct sigpending *pending)
442{
443 sigset_t signal, retain;
444 struct sigqueue *q, *n;
445
446 signal = pending->signal;
447 sigemptyset(&retain);
448
449 list_for_each_entry_safe(q, n, &pending->list, list) {
450 int sig = q->info.si_signo;
451
452 if (likely(q->info.si_code != SI_TIMER)) {
453 sigaddset(&retain, sig);
454 } else {
455 sigdelset(&signal, sig);
456 list_del_init(&q->list);
457 __sigqueue_free(q);
458 }
459 }
460
461 sigorsets(&pending->signal, &signal, &retain);
462}
463
464void flush_itimer_signals(void)
465{
466 struct task_struct *tsk = current;
467 unsigned long flags;
468
469 spin_lock_irqsave(&tsk->sighand->siglock, flags);
470 __flush_itimer_signals(&tsk->pending);
471 __flush_itimer_signals(&tsk->signal->shared_pending);
472 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
473}
474#endif
475
476void ignore_signals(struct task_struct *t)
477{
478 int i;
479
480 for (i = 0; i < _NSIG; ++i)
481 t->sighand->action[i].sa.sa_handler = SIG_IGN;
482
483 flush_signals(t);
484}
485
486/*
487 * Flush all handlers for a task.
488 */
489
490void
491flush_signal_handlers(struct task_struct *t, int force_default)
492{
493 int i;
494 struct k_sigaction *ka = &t->sighand->action[0];
495 for (i = _NSIG ; i != 0 ; i--) {
496 if (force_default || ka->sa.sa_handler != SIG_IGN)
497 ka->sa.sa_handler = SIG_DFL;
498 ka->sa.sa_flags = 0;
499#ifdef __ARCH_HAS_SA_RESTORER
500 ka->sa.sa_restorer = NULL;
501#endif
502 sigemptyset(&ka->sa.sa_mask);
503 ka++;
504 }
505}
506
507int unhandled_signal(struct task_struct *tsk, int sig)
508{
509 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
510 if (is_global_init(tsk))
511 return 1;
512 if (handler != SIG_IGN && handler != SIG_DFL)
513 return 0;
514 /* if ptraced, let the tracer determine */
515 return !tsk->ptrace;
516}
517
518static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
519 bool *resched_timer)
520{
521 struct sigqueue *q, *first = NULL;
522
523 /*
524 * Collect the siginfo appropriate to this signal. Check if
525 * there is another siginfo for the same signal.
526 */
527 list_for_each_entry(q, &list->list, list) {
528 if (q->info.si_signo == sig) {
529 if (first)
530 goto still_pending;
531 first = q;
532 }
533 }
534
535 sigdelset(&list->signal, sig);
536
537 if (first) {
538still_pending:
539 list_del_init(&first->list);
540 copy_siginfo(info, &first->info);
541
542 *resched_timer =
543 (first->flags & SIGQUEUE_PREALLOC) &&
544 (info->si_code == SI_TIMER) &&
545 (info->si_sys_private);
546
547 __sigqueue_free(first);
548 } else {
549 /*
550 * Ok, it wasn't in the queue. This must be
551 * a fast-pathed signal or we must have been
552 * out of queue space. So zero out the info.
553 */
554 clear_siginfo(info);
555 info->si_signo = sig;
556 info->si_errno = 0;
557 info->si_code = SI_USER;
558 info->si_pid = 0;
559 info->si_uid = 0;
560 }
561}
562
563static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
564 siginfo_t *info, bool *resched_timer)
565{
566 int sig = next_signal(pending, mask);
567
568 if (sig)
569 collect_signal(sig, pending, info, resched_timer);
570 return sig;
571}
572
573/*
574 * Dequeue a signal and return the element to the caller, which is
575 * expected to free it.
576 *
577 * All callers have to hold the siglock.
578 */
579int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
580{
581 bool resched_timer = false;
582 int signr;
583
584 /* We only dequeue private signals from ourselves, we don't let
585 * signalfd steal them
586 */
587 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
588 if (!signr) {
589 signr = __dequeue_signal(&tsk->signal->shared_pending,
590 mask, info, &resched_timer);
591#ifdef CONFIG_POSIX_TIMERS
592 /*
593 * itimer signal ?
594 *
595 * itimers are process shared and we restart periodic
596 * itimers in the signal delivery path to prevent DoS
597 * attacks in the high resolution timer case. This is
598 * compliant with the old way of self-restarting
599 * itimers, as the SIGALRM is a legacy signal and only
600 * queued once. Changing the restart behaviour to
601 * restart the timer in the signal dequeue path is
602 * reducing the timer noise on heavy loaded !highres
603 * systems too.
604 */
605 if (unlikely(signr == SIGALRM)) {
606 struct hrtimer *tmr = &tsk->signal->real_timer;
607
608 if (!hrtimer_is_queued(tmr) &&
609 tsk->signal->it_real_incr != 0) {
610 hrtimer_forward(tmr, tmr->base->get_time(),
611 tsk->signal->it_real_incr);
612 hrtimer_restart(tmr);
613 }
614 }
615#endif
616 }
617
618 recalc_sigpending();
619 if (!signr)
620 return 0;
621
622 if (unlikely(sig_kernel_stop(signr))) {
623 /*
624 * Set a marker that we have dequeued a stop signal. Our
625 * caller might release the siglock and then the pending
626 * stop signal it is about to process is no longer in the
627 * pending bitmasks, but must still be cleared by a SIGCONT
628 * (and overruled by a SIGKILL). So those cases clear this
629 * shared flag after we've set it. Note that this flag may
630 * remain set after the signal we return is ignored or
631 * handled. That doesn't matter because its only purpose
632 * is to alert stop-signal processing code when another
633 * processor has come along and cleared the flag.
634 */
635 current->jobctl |= JOBCTL_STOP_DEQUEUED;
636 }
637#ifdef CONFIG_POSIX_TIMERS
638 if (resched_timer) {
639 /*
640 * Release the siglock to ensure proper locking order
641 * of timer locks outside of siglocks. Note, we leave
642 * irqs disabled here, since the posix-timers code is
643 * about to disable them again anyway.
644 */
645 spin_unlock(&tsk->sighand->siglock);
646 posixtimer_rearm(info);
647 spin_lock(&tsk->sighand->siglock);
648
649 /* Don't expose the si_sys_private value to userspace */
650 info->si_sys_private = 0;
651 }
652#endif
653 return signr;
654}
655
656/*
657 * Tell a process that it has a new active signal..
658 *
659 * NOTE! we rely on the previous spin_lock to
660 * lock interrupts for us! We can only be called with
661 * "siglock" held, and the local interrupt must
662 * have been disabled when that got acquired!
663 *
664 * No need to set need_resched since signal event passing
665 * goes through ->blocked
666 */
667void signal_wake_up_state(struct task_struct *t, unsigned int state)
668{
669 set_tsk_thread_flag(t, TIF_SIGPENDING);
670 /*
671 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
672 * case. We don't check t->state here because there is a race with it
673 * executing another processor and just now entering stopped state.
674 * By using wake_up_state, we ensure the process will wake up and
675 * handle its death signal.
676 */
677 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
678 kick_process(t);
679}
680
681/*
682 * Remove signals in mask from the pending set and queue.
683 * Returns 1 if any signals were found.
684 *
685 * All callers must be holding the siglock.
686 */
687static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
688{
689 struct sigqueue *q, *n;
690 sigset_t m;
691
692 sigandsets(&m, mask, &s->signal);
693 if (sigisemptyset(&m))
694 return 0;
695
696 sigandnsets(&s->signal, &s->signal, mask);
697 list_for_each_entry_safe(q, n, &s->list, list) {
698 if (sigismember(mask, q->info.si_signo)) {
699 list_del_init(&q->list);
700 __sigqueue_free(q);
701 }
702 }
703 return 1;
704}
705
706static inline int is_si_special(const struct siginfo *info)
707{
708 return info <= SEND_SIG_FORCED;
709}
710
711static inline bool si_fromuser(const struct siginfo *info)
712{
713 return info == SEND_SIG_NOINFO ||
714 (!is_si_special(info) && SI_FROMUSER(info));
715}
716
717/*
718 * called with RCU read lock from check_kill_permission()
719 */
720static int kill_ok_by_cred(struct task_struct *t)
721{
722 const struct cred *cred = current_cred();
723 const struct cred *tcred = __task_cred(t);
724
725 if (uid_eq(cred->euid, tcred->suid) ||
726 uid_eq(cred->euid, tcred->uid) ||
727 uid_eq(cred->uid, tcred->suid) ||
728 uid_eq(cred->uid, tcred->uid))
729 return 1;
730
731 if (ns_capable(tcred->user_ns, CAP_KILL))
732 return 1;
733
734 return 0;
735}
736
737/*
738 * Bad permissions for sending the signal
739 * - the caller must hold the RCU read lock
740 */
741static int check_kill_permission(int sig, struct siginfo *info,
742 struct task_struct *t)
743{
744 struct pid *sid;
745 int error;
746
747 if (!valid_signal(sig))
748 return -EINVAL;
749
750 if (!si_fromuser(info))
751 return 0;
752
753 error = audit_signal_info(sig, t); /* Let audit system see the signal */
754 if (error)
755 return error;
756
757 if (!same_thread_group(current, t) &&
758 !kill_ok_by_cred(t)) {
759 switch (sig) {
760 case SIGCONT:
761 sid = task_session(t);
762 /*
763 * We don't return the error if sid == NULL. The
764 * task was unhashed, the caller must notice this.
765 */
766 if (!sid || sid == task_session(current))
767 break;
768 default:
769 return -EPERM;
770 }
771 }
772
773 return security_task_kill(t, info, sig, NULL);
774}
775
776/**
777 * ptrace_trap_notify - schedule trap to notify ptracer
778 * @t: tracee wanting to notify tracer
779 *
780 * This function schedules sticky ptrace trap which is cleared on the next
781 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
782 * ptracer.
783 *
784 * If @t is running, STOP trap will be taken. If trapped for STOP and
785 * ptracer is listening for events, tracee is woken up so that it can
786 * re-trap for the new event. If trapped otherwise, STOP trap will be
787 * eventually taken without returning to userland after the existing traps
788 * are finished by PTRACE_CONT.
789 *
790 * CONTEXT:
791 * Must be called with @task->sighand->siglock held.
792 */
793static void ptrace_trap_notify(struct task_struct *t)
794{
795 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
796 assert_spin_locked(&t->sighand->siglock);
797
798 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
799 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
800}
801
802/*
803 * Handle magic process-wide effects of stop/continue signals. Unlike
804 * the signal actions, these happen immediately at signal-generation
805 * time regardless of blocking, ignoring, or handling. This does the
806 * actual continuing for SIGCONT, but not the actual stopping for stop
807 * signals. The process stop is done as a signal action for SIG_DFL.
808 *
809 * Returns true if the signal should be actually delivered, otherwise
810 * it should be dropped.
811 */
812static bool prepare_signal(int sig, struct task_struct *p, bool force)
813{
814 struct signal_struct *signal = p->signal;
815 struct task_struct *t;
816 sigset_t flush;
817
818 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
819 if (!(signal->flags & SIGNAL_GROUP_EXIT))
820 return sig == SIGKILL;
821 /*
822 * The process is in the middle of dying, nothing to do.
823 */
824 } else if (sig_kernel_stop(sig)) {
825 /*
826 * This is a stop signal. Remove SIGCONT from all queues.
827 */
828 siginitset(&flush, sigmask(SIGCONT));
829 flush_sigqueue_mask(&flush, &signal->shared_pending);
830 for_each_thread(p, t)
831 flush_sigqueue_mask(&flush, &t->pending);
832 } else if (sig == SIGCONT) {
833 unsigned int why;
834 /*
835 * Remove all stop signals from all queues, wake all threads.
836 */
837 siginitset(&flush, SIG_KERNEL_STOP_MASK);
838 flush_sigqueue_mask(&flush, &signal->shared_pending);
839 for_each_thread(p, t) {
840 flush_sigqueue_mask(&flush, &t->pending);
841 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
842 if (likely(!(t->ptrace & PT_SEIZED)))
843 wake_up_state(t, __TASK_STOPPED);
844 else
845 ptrace_trap_notify(t);
846 }
847
848 /*
849 * Notify the parent with CLD_CONTINUED if we were stopped.
850 *
851 * If we were in the middle of a group stop, we pretend it
852 * was already finished, and then continued. Since SIGCHLD
853 * doesn't queue we report only CLD_STOPPED, as if the next
854 * CLD_CONTINUED was dropped.
855 */
856 why = 0;
857 if (signal->flags & SIGNAL_STOP_STOPPED)
858 why |= SIGNAL_CLD_CONTINUED;
859 else if (signal->group_stop_count)
860 why |= SIGNAL_CLD_STOPPED;
861
862 if (why) {
863 /*
864 * The first thread which returns from do_signal_stop()
865 * will take ->siglock, notice SIGNAL_CLD_MASK, and
866 * notify its parent. See get_signal_to_deliver().
867 */
868 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
869 signal->group_stop_count = 0;
870 signal->group_exit_code = 0;
871 }
872 }
873
874 return !sig_ignored(p, sig, force);
875}
876
877/*
878 * Test if P wants to take SIG. After we've checked all threads with this,
879 * it's equivalent to finding no threads not blocking SIG. Any threads not
880 * blocking SIG were ruled out because they are not running and already
881 * have pending signals. Such threads will dequeue from the shared queue
882 * as soon as they're available, so putting the signal on the shared queue
883 * will be equivalent to sending it to one such thread.
884 */
885static inline int wants_signal(int sig, struct task_struct *p)
886{
887 if (sigismember(&p->blocked, sig))
888 return 0;
889 if (p->flags & PF_EXITING)
890 return 0;
891 if (sig == SIGKILL)
892 return 1;
893 if (task_is_stopped_or_traced(p))
894 return 0;
895 return task_curr(p) || !signal_pending(p);
896}
897
898static void complete_signal(int sig, struct task_struct *p, int group)
899{
900 struct signal_struct *signal = p->signal;
901 struct task_struct *t;
902
903 /*
904 * Now find a thread we can wake up to take the signal off the queue.
905 *
906 * If the main thread wants the signal, it gets first crack.
907 * Probably the least surprising to the average bear.
908 */
909 if (wants_signal(sig, p))
910 t = p;
911 else if (!group || thread_group_empty(p))
912 /*
913 * There is just one thread and it does not need to be woken.
914 * It will dequeue unblocked signals before it runs again.
915 */
916 return;
917 else {
918 /*
919 * Otherwise try to find a suitable thread.
920 */
921 t = signal->curr_target;
922 while (!wants_signal(sig, t)) {
923 t = next_thread(t);
924 if (t == signal->curr_target)
925 /*
926 * No thread needs to be woken.
927 * Any eligible threads will see
928 * the signal in the queue soon.
929 */
930 return;
931 }
932 signal->curr_target = t;
933 }
934
935 /*
936 * Found a killable thread. If the signal will be fatal,
937 * then start taking the whole group down immediately.
938 */
939 if (sig_fatal(p, sig) &&
940 !(signal->flags & SIGNAL_GROUP_EXIT) &&
941 !sigismember(&t->real_blocked, sig) &&
942 (sig == SIGKILL || !p->ptrace)) {
943 /*
944 * This signal will be fatal to the whole group.
945 */
946 if (!sig_kernel_coredump(sig)) {
947 /*
948 * Start a group exit and wake everybody up.
949 * This way we don't have other threads
950 * running and doing things after a slower
951 * thread has the fatal signal pending.
952 */
953 signal->flags = SIGNAL_GROUP_EXIT;
954 signal->group_exit_code = sig;
955 signal->group_stop_count = 0;
956 t = p;
957 do {
958 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
959 sigaddset(&t->pending.signal, SIGKILL);
960 signal_wake_up(t, 1);
961 } while_each_thread(p, t);
962 return;
963 }
964 }
965
966 /*
967 * The signal is already in the shared-pending queue.
968 * Tell the chosen thread to wake up and dequeue it.
969 */
970 signal_wake_up(t, sig == SIGKILL);
971 return;
972}
973
974static inline int legacy_queue(struct sigpending *signals, int sig)
975{
976 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
977}
978
979#ifdef CONFIG_USER_NS
980static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
981{
982 if (current_user_ns() == task_cred_xxx(t, user_ns))
983 return;
984
985 if (SI_FROMKERNEL(info))
986 return;
987
988 rcu_read_lock();
989 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
990 make_kuid(current_user_ns(), info->si_uid));
991 rcu_read_unlock();
992}
993#else
994static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
995{
996 return;
997}
998#endif
999
1000static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1001 int group, int from_ancestor_ns)
1002{
1003 struct sigpending *pending;
1004 struct sigqueue *q;
1005 int override_rlimit;
1006 int ret = 0, result;
1007
1008 assert_spin_locked(&t->sighand->siglock);
1009
1010 result = TRACE_SIGNAL_IGNORED;
1011 if (!prepare_signal(sig, t,
1012 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1013 goto ret;
1014
1015 pending = group ? &t->signal->shared_pending : &t->pending;
1016 /*
1017 * Short-circuit ignored signals and support queuing
1018 * exactly one non-rt signal, so that we can get more
1019 * detailed information about the cause of the signal.
1020 */
1021 result = TRACE_SIGNAL_ALREADY_PENDING;
1022 if (legacy_queue(pending, sig))
1023 goto ret;
1024
1025 result = TRACE_SIGNAL_DELIVERED;
1026 /*
1027 * fast-pathed signals for kernel-internal things like SIGSTOP
1028 * or SIGKILL.
1029 */
1030 if (info == SEND_SIG_FORCED)
1031 goto out_set;
1032
1033 /*
1034 * Real-time signals must be queued if sent by sigqueue, or
1035 * some other real-time mechanism. It is implementation
1036 * defined whether kill() does so. We attempt to do so, on
1037 * the principle of least surprise, but since kill is not
1038 * allowed to fail with EAGAIN when low on memory we just
1039 * make sure at least one signal gets delivered and don't
1040 * pass on the info struct.
1041 */
1042 if (sig < SIGRTMIN)
1043 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1044 else
1045 override_rlimit = 0;
1046
1047 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1048 if (q) {
1049 list_add_tail(&q->list, &pending->list);
1050 switch ((unsigned long) info) {
1051 case (unsigned long) SEND_SIG_NOINFO:
1052 clear_siginfo(&q->info);
1053 q->info.si_signo = sig;
1054 q->info.si_errno = 0;
1055 q->info.si_code = SI_USER;
1056 q->info.si_pid = task_tgid_nr_ns(current,
1057 task_active_pid_ns(t));
1058 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1059 break;
1060 case (unsigned long) SEND_SIG_PRIV:
1061 clear_siginfo(&q->info);
1062 q->info.si_signo = sig;
1063 q->info.si_errno = 0;
1064 q->info.si_code = SI_KERNEL;
1065 q->info.si_pid = 0;
1066 q->info.si_uid = 0;
1067 break;
1068 default:
1069 copy_siginfo(&q->info, info);
1070 if (from_ancestor_ns)
1071 q->info.si_pid = 0;
1072 break;
1073 }
1074
1075 userns_fixup_signal_uid(&q->info, t);
1076
1077 } else if (!is_si_special(info)) {
1078 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1079 /*
1080 * Queue overflow, abort. We may abort if the
1081 * signal was rt and sent by user using something
1082 * other than kill().
1083 */
1084 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1085 ret = -EAGAIN;
1086 goto ret;
1087 } else {
1088 /*
1089 * This is a silent loss of information. We still
1090 * send the signal, but the *info bits are lost.
1091 */
1092 result = TRACE_SIGNAL_LOSE_INFO;
1093 }
1094 }
1095
1096out_set:
1097 signalfd_notify(t, sig);
1098 sigaddset(&pending->signal, sig);
1099 complete_signal(sig, t, group);
1100ret:
1101 trace_signal_generate(sig, info, t, group, result);
1102 return ret;
1103}
1104
1105static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1106 int group)
1107{
1108 int from_ancestor_ns = 0;
1109
1110#ifdef CONFIG_PID_NS
1111 from_ancestor_ns = si_fromuser(info) &&
1112 !task_pid_nr_ns(current, task_active_pid_ns(t));
1113#endif
1114
1115 return __send_signal(sig, info, t, group, from_ancestor_ns);
1116}
1117
1118static void print_fatal_signal(int signr)
1119{
1120 struct pt_regs *regs = signal_pt_regs();
1121 pr_info("potentially unexpected fatal signal %d.\n", signr);
1122
1123#if defined(__i386__) && !defined(__arch_um__)
1124 pr_info("code at %08lx: ", regs->ip);
1125 {
1126 int i;
1127 for (i = 0; i < 16; i++) {
1128 unsigned char insn;
1129
1130 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1131 break;
1132 pr_cont("%02x ", insn);
1133 }
1134 }
1135 pr_cont("\n");
1136#endif
1137 preempt_disable();
1138 show_regs(regs);
1139 preempt_enable();
1140}
1141
1142static int __init setup_print_fatal_signals(char *str)
1143{
1144 get_option (&str, &print_fatal_signals);
1145
1146 return 1;
1147}
1148
1149__setup("print-fatal-signals=", setup_print_fatal_signals);
1150
1151int
1152__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1153{
1154 return send_signal(sig, info, p, 1);
1155}
1156
1157static int
1158specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1159{
1160 return send_signal(sig, info, t, 0);
1161}
1162
1163int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1164 bool group)
1165{
1166 unsigned long flags;
1167 int ret = -ESRCH;
1168
1169 if (lock_task_sighand(p, &flags)) {
1170 ret = send_signal(sig, info, p, group);
1171 unlock_task_sighand(p, &flags);
1172 }
1173
1174 return ret;
1175}
1176
1177/*
1178 * Force a signal that the process can't ignore: if necessary
1179 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1180 *
1181 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1182 * since we do not want to have a signal handler that was blocked
1183 * be invoked when user space had explicitly blocked it.
1184 *
1185 * We don't want to have recursive SIGSEGV's etc, for example,
1186 * that is why we also clear SIGNAL_UNKILLABLE.
1187 */
1188int
1189force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1190{
1191 unsigned long int flags;
1192 int ret, blocked, ignored;
1193 struct k_sigaction *action;
1194
1195 spin_lock_irqsave(&t->sighand->siglock, flags);
1196 action = &t->sighand->action[sig-1];
1197 ignored = action->sa.sa_handler == SIG_IGN;
1198 blocked = sigismember(&t->blocked, sig);
1199 if (blocked || ignored) {
1200 action->sa.sa_handler = SIG_DFL;
1201 if (blocked) {
1202 sigdelset(&t->blocked, sig);
1203 recalc_sigpending_and_wake(t);
1204 }
1205 }
1206 /*
1207 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1208 * debugging to leave init killable.
1209 */
1210 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1211 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1212 ret = specific_send_sig_info(sig, info, t);
1213 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1214
1215 return ret;
1216}
1217
1218/*
1219 * Nuke all other threads in the group.
1220 */
1221int zap_other_threads(struct task_struct *p)
1222{
1223 struct task_struct *t = p;
1224 int count = 0;
1225
1226 p->signal->group_stop_count = 0;
1227
1228 while_each_thread(p, t) {
1229 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1230 count++;
1231
1232 /* Don't bother with already dead threads */
1233 if (t->exit_state)
1234 continue;
1235 sigaddset(&t->pending.signal, SIGKILL);
1236 signal_wake_up(t, 1);
1237 }
1238
1239 return count;
1240}
1241
1242struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1243 unsigned long *flags)
1244{
1245 struct sighand_struct *sighand;
1246
1247 for (;;) {
1248 /*
1249 * Disable interrupts early to avoid deadlocks.
1250 * See rcu_read_unlock() comment header for details.
1251 */
1252 local_irq_save(*flags);
1253 rcu_read_lock();
1254 sighand = rcu_dereference(tsk->sighand);
1255 if (unlikely(sighand == NULL)) {
1256 rcu_read_unlock();
1257 local_irq_restore(*flags);
1258 break;
1259 }
1260 /*
1261 * This sighand can be already freed and even reused, but
1262 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1263 * initializes ->siglock: this slab can't go away, it has
1264 * the same object type, ->siglock can't be reinitialized.
1265 *
1266 * We need to ensure that tsk->sighand is still the same
1267 * after we take the lock, we can race with de_thread() or
1268 * __exit_signal(). In the latter case the next iteration
1269 * must see ->sighand == NULL.
1270 */
1271 spin_lock(&sighand->siglock);
1272 if (likely(sighand == tsk->sighand)) {
1273 rcu_read_unlock();
1274 break;
1275 }
1276 spin_unlock(&sighand->siglock);
1277 rcu_read_unlock();
1278 local_irq_restore(*flags);
1279 }
1280
1281 return sighand;
1282}
1283
1284/*
1285 * send signal info to all the members of a group
1286 */
1287int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1288{
1289 int ret;
1290
1291 rcu_read_lock();
1292 ret = check_kill_permission(sig, info, p);
1293 rcu_read_unlock();
1294
1295 if (!ret && sig)
1296 ret = do_send_sig_info(sig, info, p, true);
1297
1298 return ret;
1299}
1300
1301/*
1302 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1303 * control characters do (^C, ^Z etc)
1304 * - the caller must hold at least a readlock on tasklist_lock
1305 */
1306int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1307{
1308 struct task_struct *p = NULL;
1309 int retval, success;
1310
1311 success = 0;
1312 retval = -ESRCH;
1313 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1314 int err = group_send_sig_info(sig, info, p);
1315 success |= !err;
1316 retval = err;
1317 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1318 return success ? 0 : retval;
1319}
1320
1321int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1322{
1323 int error = -ESRCH;
1324 struct task_struct *p;
1325
1326 for (;;) {
1327 rcu_read_lock();
1328 p = pid_task(pid, PIDTYPE_PID);
1329 if (p)
1330 error = group_send_sig_info(sig, info, p);
1331 rcu_read_unlock();
1332 if (likely(!p || error != -ESRCH))
1333 return error;
1334
1335 /*
1336 * The task was unhashed in between, try again. If it
1337 * is dead, pid_task() will return NULL, if we race with
1338 * de_thread() it will find the new leader.
1339 */
1340 }
1341}
1342
1343static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1344{
1345 int error;
1346 rcu_read_lock();
1347 error = kill_pid_info(sig, info, find_vpid(pid));
1348 rcu_read_unlock();
1349 return error;
1350}
1351
1352static int kill_as_cred_perm(const struct cred *cred,
1353 struct task_struct *target)
1354{
1355 const struct cred *pcred = __task_cred(target);
1356 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1357 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1358 return 0;
1359 return 1;
1360}
1361
1362/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1363int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1364 const struct cred *cred)
1365{
1366 int ret = -EINVAL;
1367 struct task_struct *p;
1368 unsigned long flags;
1369
1370 if (!valid_signal(sig))
1371 return ret;
1372
1373 rcu_read_lock();
1374 p = pid_task(pid, PIDTYPE_PID);
1375 if (!p) {
1376 ret = -ESRCH;
1377 goto out_unlock;
1378 }
1379 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1380 ret = -EPERM;
1381 goto out_unlock;
1382 }
1383 ret = security_task_kill(p, info, sig, cred);
1384 if (ret)
1385 goto out_unlock;
1386
1387 if (sig) {
1388 if (lock_task_sighand(p, &flags)) {
1389 ret = __send_signal(sig, info, p, 1, 0);
1390 unlock_task_sighand(p, &flags);
1391 } else
1392 ret = -ESRCH;
1393 }
1394out_unlock:
1395 rcu_read_unlock();
1396 return ret;
1397}
1398EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1399
1400/*
1401 * kill_something_info() interprets pid in interesting ways just like kill(2).
1402 *
1403 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1404 * is probably wrong. Should make it like BSD or SYSV.
1405 */
1406
1407static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1408{
1409 int ret;
1410
1411 if (pid > 0) {
1412 rcu_read_lock();
1413 ret = kill_pid_info(sig, info, find_vpid(pid));
1414 rcu_read_unlock();
1415 return ret;
1416 }
1417
1418 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1419 if (pid == INT_MIN)
1420 return -ESRCH;
1421
1422 read_lock(&tasklist_lock);
1423 if (pid != -1) {
1424 ret = __kill_pgrp_info(sig, info,
1425 pid ? find_vpid(-pid) : task_pgrp(current));
1426 } else {
1427 int retval = 0, count = 0;
1428 struct task_struct * p;
1429
1430 for_each_process(p) {
1431 if (task_pid_vnr(p) > 1 &&
1432 !same_thread_group(p, current)) {
1433 int err = group_send_sig_info(sig, info, p);
1434 ++count;
1435 if (err != -EPERM)
1436 retval = err;
1437 }
1438 }
1439 ret = count ? retval : -ESRCH;
1440 }
1441 read_unlock(&tasklist_lock);
1442
1443 return ret;
1444}
1445
1446/*
1447 * These are for backward compatibility with the rest of the kernel source.
1448 */
1449
1450int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1451{
1452 /*
1453 * Make sure legacy kernel users don't send in bad values
1454 * (normal paths check this in check_kill_permission).
1455 */
1456 if (!valid_signal(sig))
1457 return -EINVAL;
1458
1459 return do_send_sig_info(sig, info, p, false);
1460}
1461
1462#define __si_special(priv) \
1463 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1464
1465int
1466send_sig(int sig, struct task_struct *p, int priv)
1467{
1468 return send_sig_info(sig, __si_special(priv), p);
1469}
1470
1471void
1472force_sig(int sig, struct task_struct *p)
1473{
1474 force_sig_info(sig, SEND_SIG_PRIV, p);
1475}
1476
1477/*
1478 * When things go south during signal handling, we
1479 * will force a SIGSEGV. And if the signal that caused
1480 * the problem was already a SIGSEGV, we'll want to
1481 * make sure we don't even try to deliver the signal..
1482 */
1483int
1484force_sigsegv(int sig, struct task_struct *p)
1485{
1486 if (sig == SIGSEGV) {
1487 unsigned long flags;
1488 spin_lock_irqsave(&p->sighand->siglock, flags);
1489 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1490 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1491 }
1492 force_sig(SIGSEGV, p);
1493 return 0;
1494}
1495
1496int force_sig_fault(int sig, int code, void __user *addr
1497 ___ARCH_SI_TRAPNO(int trapno)
1498 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1499 , struct task_struct *t)
1500{
1501 struct siginfo info;
1502
1503 clear_siginfo(&info);
1504 info.si_signo = sig;
1505 info.si_errno = 0;
1506 info.si_code = code;
1507 info.si_addr = addr;
1508#ifdef __ARCH_SI_TRAPNO
1509 info.si_trapno = trapno;
1510#endif
1511#ifdef __ia64__
1512 info.si_imm = imm;
1513 info.si_flags = flags;
1514 info.si_isr = isr;
1515#endif
1516 return force_sig_info(info.si_signo, &info, t);
1517}
1518
1519int send_sig_fault(int sig, int code, void __user *addr
1520 ___ARCH_SI_TRAPNO(int trapno)
1521 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1522 , struct task_struct *t)
1523{
1524 struct siginfo info;
1525
1526 clear_siginfo(&info);
1527 info.si_signo = sig;
1528 info.si_errno = 0;
1529 info.si_code = code;
1530 info.si_addr = addr;
1531#ifdef __ARCH_SI_TRAPNO
1532 info.si_trapno = trapno;
1533#endif
1534#ifdef __ia64__
1535 info.si_imm = imm;
1536 info.si_flags = flags;
1537 info.si_isr = isr;
1538#endif
1539 return send_sig_info(info.si_signo, &info, t);
1540}
1541
1542#if defined(BUS_MCEERR_AO) && defined(BUS_MCEERR_AR)
1543int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1544{
1545 struct siginfo info;
1546
1547 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1548 clear_siginfo(&info);
1549 info.si_signo = SIGBUS;
1550 info.si_errno = 0;
1551 info.si_code = code;
1552 info.si_addr = addr;
1553 info.si_addr_lsb = lsb;
1554 return force_sig_info(info.si_signo, &info, t);
1555}
1556
1557int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1558{
1559 struct siginfo info;
1560
1561 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1562 clear_siginfo(&info);
1563 info.si_signo = SIGBUS;
1564 info.si_errno = 0;
1565 info.si_code = code;
1566 info.si_addr = addr;
1567 info.si_addr_lsb = lsb;
1568 return send_sig_info(info.si_signo, &info, t);
1569}
1570EXPORT_SYMBOL(send_sig_mceerr);
1571#endif
1572
1573#ifdef SEGV_BNDERR
1574int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1575{
1576 struct siginfo info;
1577
1578 clear_siginfo(&info);
1579 info.si_signo = SIGSEGV;
1580 info.si_errno = 0;
1581 info.si_code = SEGV_BNDERR;
1582 info.si_addr = addr;
1583 info.si_lower = lower;
1584 info.si_upper = upper;
1585 return force_sig_info(info.si_signo, &info, current);
1586}
1587#endif
1588
1589#ifdef SEGV_PKUERR
1590int force_sig_pkuerr(void __user *addr, u32 pkey)
1591{
1592 struct siginfo info;
1593
1594 clear_siginfo(&info);
1595 info.si_signo = SIGSEGV;
1596 info.si_errno = 0;
1597 info.si_code = SEGV_PKUERR;
1598 info.si_addr = addr;
1599 info.si_pkey = pkey;
1600 return force_sig_info(info.si_signo, &info, current);
1601}
1602#endif
1603
1604/* For the crazy architectures that include trap information in
1605 * the errno field, instead of an actual errno value.
1606 */
1607int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1608{
1609 struct siginfo info;
1610
1611 clear_siginfo(&info);
1612 info.si_signo = SIGTRAP;
1613 info.si_errno = errno;
1614 info.si_code = TRAP_HWBKPT;
1615 info.si_addr = addr;
1616 return force_sig_info(info.si_signo, &info, current);
1617}
1618
1619int kill_pgrp(struct pid *pid, int sig, int priv)
1620{
1621 int ret;
1622
1623 read_lock(&tasklist_lock);
1624 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1625 read_unlock(&tasklist_lock);
1626
1627 return ret;
1628}
1629EXPORT_SYMBOL(kill_pgrp);
1630
1631int kill_pid(struct pid *pid, int sig, int priv)
1632{
1633 return kill_pid_info(sig, __si_special(priv), pid);
1634}
1635EXPORT_SYMBOL(kill_pid);
1636
1637/*
1638 * These functions support sending signals using preallocated sigqueue
1639 * structures. This is needed "because realtime applications cannot
1640 * afford to lose notifications of asynchronous events, like timer
1641 * expirations or I/O completions". In the case of POSIX Timers
1642 * we allocate the sigqueue structure from the timer_create. If this
1643 * allocation fails we are able to report the failure to the application
1644 * with an EAGAIN error.
1645 */
1646struct sigqueue *sigqueue_alloc(void)
1647{
1648 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1649
1650 if (q)
1651 q->flags |= SIGQUEUE_PREALLOC;
1652
1653 return q;
1654}
1655
1656void sigqueue_free(struct sigqueue *q)
1657{
1658 unsigned long flags;
1659 spinlock_t *lock = ¤t->sighand->siglock;
1660
1661 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1662 /*
1663 * We must hold ->siglock while testing q->list
1664 * to serialize with collect_signal() or with
1665 * __exit_signal()->flush_sigqueue().
1666 */
1667 spin_lock_irqsave(lock, flags);
1668 q->flags &= ~SIGQUEUE_PREALLOC;
1669 /*
1670 * If it is queued it will be freed when dequeued,
1671 * like the "regular" sigqueue.
1672 */
1673 if (!list_empty(&q->list))
1674 q = NULL;
1675 spin_unlock_irqrestore(lock, flags);
1676
1677 if (q)
1678 __sigqueue_free(q);
1679}
1680
1681int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1682{
1683 int sig = q->info.si_signo;
1684 struct sigpending *pending;
1685 unsigned long flags;
1686 int ret, result;
1687
1688 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1689
1690 ret = -1;
1691 if (!likely(lock_task_sighand(t, &flags)))
1692 goto ret;
1693
1694 ret = 1; /* the signal is ignored */
1695 result = TRACE_SIGNAL_IGNORED;
1696 if (!prepare_signal(sig, t, false))
1697 goto out;
1698
1699 ret = 0;
1700 if (unlikely(!list_empty(&q->list))) {
1701 /*
1702 * If an SI_TIMER entry is already queue just increment
1703 * the overrun count.
1704 */
1705 BUG_ON(q->info.si_code != SI_TIMER);
1706 q->info.si_overrun++;
1707 result = TRACE_SIGNAL_ALREADY_PENDING;
1708 goto out;
1709 }
1710 q->info.si_overrun = 0;
1711
1712 signalfd_notify(t, sig);
1713 pending = group ? &t->signal->shared_pending : &t->pending;
1714 list_add_tail(&q->list, &pending->list);
1715 sigaddset(&pending->signal, sig);
1716 complete_signal(sig, t, group);
1717 result = TRACE_SIGNAL_DELIVERED;
1718out:
1719 trace_signal_generate(sig, &q->info, t, group, result);
1720 unlock_task_sighand(t, &flags);
1721ret:
1722 return ret;
1723}
1724
1725/*
1726 * Let a parent know about the death of a child.
1727 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1728 *
1729 * Returns true if our parent ignored us and so we've switched to
1730 * self-reaping.
1731 */
1732bool do_notify_parent(struct task_struct *tsk, int sig)
1733{
1734 struct siginfo info;
1735 unsigned long flags;
1736 struct sighand_struct *psig;
1737 bool autoreap = false;
1738 u64 utime, stime;
1739
1740 BUG_ON(sig == -1);
1741
1742 /* do_notify_parent_cldstop should have been called instead. */
1743 BUG_ON(task_is_stopped_or_traced(tsk));
1744
1745 BUG_ON(!tsk->ptrace &&
1746 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1747
1748 if (sig != SIGCHLD) {
1749 /*
1750 * This is only possible if parent == real_parent.
1751 * Check if it has changed security domain.
1752 */
1753 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1754 sig = SIGCHLD;
1755 }
1756
1757 clear_siginfo(&info);
1758 info.si_signo = sig;
1759 info.si_errno = 0;
1760 /*
1761 * We are under tasklist_lock here so our parent is tied to
1762 * us and cannot change.
1763 *
1764 * task_active_pid_ns will always return the same pid namespace
1765 * until a task passes through release_task.
1766 *
1767 * write_lock() currently calls preempt_disable() which is the
1768 * same as rcu_read_lock(), but according to Oleg, this is not
1769 * correct to rely on this
1770 */
1771 rcu_read_lock();
1772 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1773 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1774 task_uid(tsk));
1775 rcu_read_unlock();
1776
1777 task_cputime(tsk, &utime, &stime);
1778 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1779 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1780
1781 info.si_status = tsk->exit_code & 0x7f;
1782 if (tsk->exit_code & 0x80)
1783 info.si_code = CLD_DUMPED;
1784 else if (tsk->exit_code & 0x7f)
1785 info.si_code = CLD_KILLED;
1786 else {
1787 info.si_code = CLD_EXITED;
1788 info.si_status = tsk->exit_code >> 8;
1789 }
1790
1791 psig = tsk->parent->sighand;
1792 spin_lock_irqsave(&psig->siglock, flags);
1793 if (!tsk->ptrace && sig == SIGCHLD &&
1794 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1795 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1796 /*
1797 * We are exiting and our parent doesn't care. POSIX.1
1798 * defines special semantics for setting SIGCHLD to SIG_IGN
1799 * or setting the SA_NOCLDWAIT flag: we should be reaped
1800 * automatically and not left for our parent's wait4 call.
1801 * Rather than having the parent do it as a magic kind of
1802 * signal handler, we just set this to tell do_exit that we
1803 * can be cleaned up without becoming a zombie. Note that
1804 * we still call __wake_up_parent in this case, because a
1805 * blocked sys_wait4 might now return -ECHILD.
1806 *
1807 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1808 * is implementation-defined: we do (if you don't want
1809 * it, just use SIG_IGN instead).
1810 */
1811 autoreap = true;
1812 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1813 sig = 0;
1814 }
1815 if (valid_signal(sig) && sig)
1816 __group_send_sig_info(sig, &info, tsk->parent);
1817 __wake_up_parent(tsk, tsk->parent);
1818 spin_unlock_irqrestore(&psig->siglock, flags);
1819
1820 return autoreap;
1821}
1822
1823/**
1824 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1825 * @tsk: task reporting the state change
1826 * @for_ptracer: the notification is for ptracer
1827 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1828 *
1829 * Notify @tsk's parent that the stopped/continued state has changed. If
1830 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1831 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1832 *
1833 * CONTEXT:
1834 * Must be called with tasklist_lock at least read locked.
1835 */
1836static void do_notify_parent_cldstop(struct task_struct *tsk,
1837 bool for_ptracer, int why)
1838{
1839 struct siginfo info;
1840 unsigned long flags;
1841 struct task_struct *parent;
1842 struct sighand_struct *sighand;
1843 u64 utime, stime;
1844
1845 if (for_ptracer) {
1846 parent = tsk->parent;
1847 } else {
1848 tsk = tsk->group_leader;
1849 parent = tsk->real_parent;
1850 }
1851
1852 clear_siginfo(&info);
1853 info.si_signo = SIGCHLD;
1854 info.si_errno = 0;
1855 /*
1856 * see comment in do_notify_parent() about the following 4 lines
1857 */
1858 rcu_read_lock();
1859 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1860 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1861 rcu_read_unlock();
1862
1863 task_cputime(tsk, &utime, &stime);
1864 info.si_utime = nsec_to_clock_t(utime);
1865 info.si_stime = nsec_to_clock_t(stime);
1866
1867 info.si_code = why;
1868 switch (why) {
1869 case CLD_CONTINUED:
1870 info.si_status = SIGCONT;
1871 break;
1872 case CLD_STOPPED:
1873 info.si_status = tsk->signal->group_exit_code & 0x7f;
1874 break;
1875 case CLD_TRAPPED:
1876 info.si_status = tsk->exit_code & 0x7f;
1877 break;
1878 default:
1879 BUG();
1880 }
1881
1882 sighand = parent->sighand;
1883 spin_lock_irqsave(&sighand->siglock, flags);
1884 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1885 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1886 __group_send_sig_info(SIGCHLD, &info, parent);
1887 /*
1888 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1889 */
1890 __wake_up_parent(tsk, parent);
1891 spin_unlock_irqrestore(&sighand->siglock, flags);
1892}
1893
1894static inline int may_ptrace_stop(void)
1895{
1896 if (!likely(current->ptrace))
1897 return 0;
1898 /*
1899 * Are we in the middle of do_coredump?
1900 * If so and our tracer is also part of the coredump stopping
1901 * is a deadlock situation, and pointless because our tracer
1902 * is dead so don't allow us to stop.
1903 * If SIGKILL was already sent before the caller unlocked
1904 * ->siglock we must see ->core_state != NULL. Otherwise it
1905 * is safe to enter schedule().
1906 *
1907 * This is almost outdated, a task with the pending SIGKILL can't
1908 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1909 * after SIGKILL was already dequeued.
1910 */
1911 if (unlikely(current->mm->core_state) &&
1912 unlikely(current->mm == current->parent->mm))
1913 return 0;
1914
1915 return 1;
1916}
1917
1918/*
1919 * Return non-zero if there is a SIGKILL that should be waking us up.
1920 * Called with the siglock held.
1921 */
1922static int sigkill_pending(struct task_struct *tsk)
1923{
1924 return sigismember(&tsk->pending.signal, SIGKILL) ||
1925 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1926}
1927
1928/*
1929 * This must be called with current->sighand->siglock held.
1930 *
1931 * This should be the path for all ptrace stops.
1932 * We always set current->last_siginfo while stopped here.
1933 * That makes it a way to test a stopped process for
1934 * being ptrace-stopped vs being job-control-stopped.
1935 *
1936 * If we actually decide not to stop at all because the tracer
1937 * is gone, we keep current->exit_code unless clear_code.
1938 */
1939static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1940 __releases(¤t->sighand->siglock)
1941 __acquires(¤t->sighand->siglock)
1942{
1943 bool gstop_done = false;
1944
1945 if (arch_ptrace_stop_needed(exit_code, info)) {
1946 /*
1947 * The arch code has something special to do before a
1948 * ptrace stop. This is allowed to block, e.g. for faults
1949 * on user stack pages. We can't keep the siglock while
1950 * calling arch_ptrace_stop, so we must release it now.
1951 * To preserve proper semantics, we must do this before
1952 * any signal bookkeeping like checking group_stop_count.
1953 * Meanwhile, a SIGKILL could come in before we retake the
1954 * siglock. That must prevent us from sleeping in TASK_TRACED.
1955 * So after regaining the lock, we must check for SIGKILL.
1956 */
1957 spin_unlock_irq(¤t->sighand->siglock);
1958 arch_ptrace_stop(exit_code, info);
1959 spin_lock_irq(¤t->sighand->siglock);
1960 if (sigkill_pending(current))
1961 return;
1962 }
1963
1964 set_special_state(TASK_TRACED);
1965
1966 /*
1967 * We're committing to trapping. TRACED should be visible before
1968 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1969 * Also, transition to TRACED and updates to ->jobctl should be
1970 * atomic with respect to siglock and should be done after the arch
1971 * hook as siglock is released and regrabbed across it.
1972 *
1973 * TRACER TRACEE
1974 *
1975 * ptrace_attach()
1976 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
1977 * do_wait()
1978 * set_current_state() smp_wmb();
1979 * ptrace_do_wait()
1980 * wait_task_stopped()
1981 * task_stopped_code()
1982 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
1983 */
1984 smp_wmb();
1985
1986 current->last_siginfo = info;
1987 current->exit_code = exit_code;
1988
1989 /*
1990 * If @why is CLD_STOPPED, we're trapping to participate in a group
1991 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1992 * across siglock relocks since INTERRUPT was scheduled, PENDING
1993 * could be clear now. We act as if SIGCONT is received after
1994 * TASK_TRACED is entered - ignore it.
1995 */
1996 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1997 gstop_done = task_participate_group_stop(current);
1998
1999 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2000 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2001 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2002 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2003
2004 /* entering a trap, clear TRAPPING */
2005 task_clear_jobctl_trapping(current);
2006
2007 spin_unlock_irq(¤t->sighand->siglock);
2008 read_lock(&tasklist_lock);
2009 if (may_ptrace_stop()) {
2010 /*
2011 * Notify parents of the stop.
2012 *
2013 * While ptraced, there are two parents - the ptracer and
2014 * the real_parent of the group_leader. The ptracer should
2015 * know about every stop while the real parent is only
2016 * interested in the completion of group stop. The states
2017 * for the two don't interact with each other. Notify
2018 * separately unless they're gonna be duplicates.
2019 */
2020 do_notify_parent_cldstop(current, true, why);
2021 if (gstop_done && ptrace_reparented(current))
2022 do_notify_parent_cldstop(current, false, why);
2023
2024 /*
2025 * Don't want to allow preemption here, because
2026 * sys_ptrace() needs this task to be inactive.
2027 *
2028 * XXX: implement read_unlock_no_resched().
2029 */
2030 preempt_disable();
2031 read_unlock(&tasklist_lock);
2032 preempt_enable_no_resched();
2033 freezable_schedule();
2034 } else {
2035 /*
2036 * By the time we got the lock, our tracer went away.
2037 * Don't drop the lock yet, another tracer may come.
2038 *
2039 * If @gstop_done, the ptracer went away between group stop
2040 * completion and here. During detach, it would have set
2041 * JOBCTL_STOP_PENDING on us and we'll re-enter
2042 * TASK_STOPPED in do_signal_stop() on return, so notifying
2043 * the real parent of the group stop completion is enough.
2044 */
2045 if (gstop_done)
2046 do_notify_parent_cldstop(current, false, why);
2047
2048 /* tasklist protects us from ptrace_freeze_traced() */
2049 __set_current_state(TASK_RUNNING);
2050 if (clear_code)
2051 current->exit_code = 0;
2052 read_unlock(&tasklist_lock);
2053 }
2054
2055 /*
2056 * We are back. Now reacquire the siglock before touching
2057 * last_siginfo, so that we are sure to have synchronized with
2058 * any signal-sending on another CPU that wants to examine it.
2059 */
2060 spin_lock_irq(¤t->sighand->siglock);
2061 current->last_siginfo = NULL;
2062
2063 /* LISTENING can be set only during STOP traps, clear it */
2064 current->jobctl &= ~JOBCTL_LISTENING;
2065
2066 /*
2067 * Queued signals ignored us while we were stopped for tracing.
2068 * So check for any that we should take before resuming user mode.
2069 * This sets TIF_SIGPENDING, but never clears it.
2070 */
2071 recalc_sigpending_tsk(current);
2072}
2073
2074static void ptrace_do_notify(int signr, int exit_code, int why)
2075{
2076 siginfo_t info;
2077
2078 clear_siginfo(&info);
2079 info.si_signo = signr;
2080 info.si_code = exit_code;
2081 info.si_pid = task_pid_vnr(current);
2082 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2083
2084 /* Let the debugger run. */
2085 ptrace_stop(exit_code, why, 1, &info);
2086}
2087
2088void ptrace_notify(int exit_code)
2089{
2090 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2091 if (unlikely(current->task_works))
2092 task_work_run();
2093
2094 spin_lock_irq(¤t->sighand->siglock);
2095 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2096 spin_unlock_irq(¤t->sighand->siglock);
2097}
2098
2099/**
2100 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2101 * @signr: signr causing group stop if initiating
2102 *
2103 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2104 * and participate in it. If already set, participate in the existing
2105 * group stop. If participated in a group stop (and thus slept), %true is
2106 * returned with siglock released.
2107 *
2108 * If ptraced, this function doesn't handle stop itself. Instead,
2109 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2110 * untouched. The caller must ensure that INTERRUPT trap handling takes
2111 * places afterwards.
2112 *
2113 * CONTEXT:
2114 * Must be called with @current->sighand->siglock held, which is released
2115 * on %true return.
2116 *
2117 * RETURNS:
2118 * %false if group stop is already cancelled or ptrace trap is scheduled.
2119 * %true if participated in group stop.
2120 */
2121static bool do_signal_stop(int signr)
2122 __releases(¤t->sighand->siglock)
2123{
2124 struct signal_struct *sig = current->signal;
2125
2126 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2127 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2128 struct task_struct *t;
2129
2130 /* signr will be recorded in task->jobctl for retries */
2131 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2132
2133 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2134 unlikely(signal_group_exit(sig)))
2135 return false;
2136 /*
2137 * There is no group stop already in progress. We must
2138 * initiate one now.
2139 *
2140 * While ptraced, a task may be resumed while group stop is
2141 * still in effect and then receive a stop signal and
2142 * initiate another group stop. This deviates from the
2143 * usual behavior as two consecutive stop signals can't
2144 * cause two group stops when !ptraced. That is why we
2145 * also check !task_is_stopped(t) below.
2146 *
2147 * The condition can be distinguished by testing whether
2148 * SIGNAL_STOP_STOPPED is already set. Don't generate
2149 * group_exit_code in such case.
2150 *
2151 * This is not necessary for SIGNAL_STOP_CONTINUED because
2152 * an intervening stop signal is required to cause two
2153 * continued events regardless of ptrace.
2154 */
2155 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2156 sig->group_exit_code = signr;
2157
2158 sig->group_stop_count = 0;
2159
2160 if (task_set_jobctl_pending(current, signr | gstop))
2161 sig->group_stop_count++;
2162
2163 t = current;
2164 while_each_thread(current, t) {
2165 /*
2166 * Setting state to TASK_STOPPED for a group
2167 * stop is always done with the siglock held,
2168 * so this check has no races.
2169 */
2170 if (!task_is_stopped(t) &&
2171 task_set_jobctl_pending(t, signr | gstop)) {
2172 sig->group_stop_count++;
2173 if (likely(!(t->ptrace & PT_SEIZED)))
2174 signal_wake_up(t, 0);
2175 else
2176 ptrace_trap_notify(t);
2177 }
2178 }
2179 }
2180
2181 if (likely(!current->ptrace)) {
2182 int notify = 0;
2183
2184 /*
2185 * If there are no other threads in the group, or if there
2186 * is a group stop in progress and we are the last to stop,
2187 * report to the parent.
2188 */
2189 if (task_participate_group_stop(current))
2190 notify = CLD_STOPPED;
2191
2192 set_special_state(TASK_STOPPED);
2193 spin_unlock_irq(¤t->sighand->siglock);
2194
2195 /*
2196 * Notify the parent of the group stop completion. Because
2197 * we're not holding either the siglock or tasklist_lock
2198 * here, ptracer may attach inbetween; however, this is for
2199 * group stop and should always be delivered to the real
2200 * parent of the group leader. The new ptracer will get
2201 * its notification when this task transitions into
2202 * TASK_TRACED.
2203 */
2204 if (notify) {
2205 read_lock(&tasklist_lock);
2206 do_notify_parent_cldstop(current, false, notify);
2207 read_unlock(&tasklist_lock);
2208 }
2209
2210 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2211 freezable_schedule();
2212 return true;
2213 } else {
2214 /*
2215 * While ptraced, group stop is handled by STOP trap.
2216 * Schedule it and let the caller deal with it.
2217 */
2218 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2219 return false;
2220 }
2221}
2222
2223/**
2224 * do_jobctl_trap - take care of ptrace jobctl traps
2225 *
2226 * When PT_SEIZED, it's used for both group stop and explicit
2227 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2228 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2229 * the stop signal; otherwise, %SIGTRAP.
2230 *
2231 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2232 * number as exit_code and no siginfo.
2233 *
2234 * CONTEXT:
2235 * Must be called with @current->sighand->siglock held, which may be
2236 * released and re-acquired before returning with intervening sleep.
2237 */
2238static void do_jobctl_trap(void)
2239{
2240 struct signal_struct *signal = current->signal;
2241 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2242
2243 if (current->ptrace & PT_SEIZED) {
2244 if (!signal->group_stop_count &&
2245 !(signal->flags & SIGNAL_STOP_STOPPED))
2246 signr = SIGTRAP;
2247 WARN_ON_ONCE(!signr);
2248 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2249 CLD_STOPPED);
2250 } else {
2251 WARN_ON_ONCE(!signr);
2252 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2253 current->exit_code = 0;
2254 }
2255}
2256
2257static int ptrace_signal(int signr, siginfo_t *info)
2258{
2259 /*
2260 * We do not check sig_kernel_stop(signr) but set this marker
2261 * unconditionally because we do not know whether debugger will
2262 * change signr. This flag has no meaning unless we are going
2263 * to stop after return from ptrace_stop(). In this case it will
2264 * be checked in do_signal_stop(), we should only stop if it was
2265 * not cleared by SIGCONT while we were sleeping. See also the
2266 * comment in dequeue_signal().
2267 */
2268 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2269 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2270
2271 /* We're back. Did the debugger cancel the sig? */
2272 signr = current->exit_code;
2273 if (signr == 0)
2274 return signr;
2275
2276 current->exit_code = 0;
2277
2278 /*
2279 * Update the siginfo structure if the signal has
2280 * changed. If the debugger wanted something
2281 * specific in the siginfo structure then it should
2282 * have updated *info via PTRACE_SETSIGINFO.
2283 */
2284 if (signr != info->si_signo) {
2285 clear_siginfo(info);
2286 info->si_signo = signr;
2287 info->si_errno = 0;
2288 info->si_code = SI_USER;
2289 rcu_read_lock();
2290 info->si_pid = task_pid_vnr(current->parent);
2291 info->si_uid = from_kuid_munged(current_user_ns(),
2292 task_uid(current->parent));
2293 rcu_read_unlock();
2294 }
2295
2296 /* If the (new) signal is now blocked, requeue it. */
2297 if (sigismember(¤t->blocked, signr)) {
2298 specific_send_sig_info(signr, info, current);
2299 signr = 0;
2300 }
2301
2302 return signr;
2303}
2304
2305int get_signal(struct ksignal *ksig)
2306{
2307 struct sighand_struct *sighand = current->sighand;
2308 struct signal_struct *signal = current->signal;
2309 int signr;
2310
2311 if (unlikely(current->task_works))
2312 task_work_run();
2313
2314 if (unlikely(uprobe_deny_signal()))
2315 return 0;
2316
2317 /*
2318 * Do this once, we can't return to user-mode if freezing() == T.
2319 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2320 * thus do not need another check after return.
2321 */
2322 try_to_freeze();
2323
2324relock:
2325 spin_lock_irq(&sighand->siglock);
2326 /*
2327 * Every stopped thread goes here after wakeup. Check to see if
2328 * we should notify the parent, prepare_signal(SIGCONT) encodes
2329 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2330 */
2331 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2332 int why;
2333
2334 if (signal->flags & SIGNAL_CLD_CONTINUED)
2335 why = CLD_CONTINUED;
2336 else
2337 why = CLD_STOPPED;
2338
2339 signal->flags &= ~SIGNAL_CLD_MASK;
2340
2341 spin_unlock_irq(&sighand->siglock);
2342
2343 /*
2344 * Notify the parent that we're continuing. This event is
2345 * always per-process and doesn't make whole lot of sense
2346 * for ptracers, who shouldn't consume the state via
2347 * wait(2) either, but, for backward compatibility, notify
2348 * the ptracer of the group leader too unless it's gonna be
2349 * a duplicate.
2350 */
2351 read_lock(&tasklist_lock);
2352 do_notify_parent_cldstop(current, false, why);
2353
2354 if (ptrace_reparented(current->group_leader))
2355 do_notify_parent_cldstop(current->group_leader,
2356 true, why);
2357 read_unlock(&tasklist_lock);
2358
2359 goto relock;
2360 }
2361
2362 for (;;) {
2363 struct k_sigaction *ka;
2364
2365 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2366 do_signal_stop(0))
2367 goto relock;
2368
2369 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2370 do_jobctl_trap();
2371 spin_unlock_irq(&sighand->siglock);
2372 goto relock;
2373 }
2374
2375 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2376
2377 if (!signr)
2378 break; /* will return 0 */
2379
2380 if (unlikely(current->ptrace) && signr != SIGKILL) {
2381 signr = ptrace_signal(signr, &ksig->info);
2382 if (!signr)
2383 continue;
2384 }
2385
2386 ka = &sighand->action[signr-1];
2387
2388 /* Trace actually delivered signals. */
2389 trace_signal_deliver(signr, &ksig->info, ka);
2390
2391 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2392 continue;
2393 if (ka->sa.sa_handler != SIG_DFL) {
2394 /* Run the handler. */
2395 ksig->ka = *ka;
2396
2397 if (ka->sa.sa_flags & SA_ONESHOT)
2398 ka->sa.sa_handler = SIG_DFL;
2399
2400 break; /* will return non-zero "signr" value */
2401 }
2402
2403 /*
2404 * Now we are doing the default action for this signal.
2405 */
2406 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2407 continue;
2408
2409 /*
2410 * Global init gets no signals it doesn't want.
2411 * Container-init gets no signals it doesn't want from same
2412 * container.
2413 *
2414 * Note that if global/container-init sees a sig_kernel_only()
2415 * signal here, the signal must have been generated internally
2416 * or must have come from an ancestor namespace. In either
2417 * case, the signal cannot be dropped.
2418 */
2419 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2420 !sig_kernel_only(signr))
2421 continue;
2422
2423 if (sig_kernel_stop(signr)) {
2424 /*
2425 * The default action is to stop all threads in
2426 * the thread group. The job control signals
2427 * do nothing in an orphaned pgrp, but SIGSTOP
2428 * always works. Note that siglock needs to be
2429 * dropped during the call to is_orphaned_pgrp()
2430 * because of lock ordering with tasklist_lock.
2431 * This allows an intervening SIGCONT to be posted.
2432 * We need to check for that and bail out if necessary.
2433 */
2434 if (signr != SIGSTOP) {
2435 spin_unlock_irq(&sighand->siglock);
2436
2437 /* signals can be posted during this window */
2438
2439 if (is_current_pgrp_orphaned())
2440 goto relock;
2441
2442 spin_lock_irq(&sighand->siglock);
2443 }
2444
2445 if (likely(do_signal_stop(ksig->info.si_signo))) {
2446 /* It released the siglock. */
2447 goto relock;
2448 }
2449
2450 /*
2451 * We didn't actually stop, due to a race
2452 * with SIGCONT or something like that.
2453 */
2454 continue;
2455 }
2456
2457 spin_unlock_irq(&sighand->siglock);
2458
2459 /*
2460 * Anything else is fatal, maybe with a core dump.
2461 */
2462 current->flags |= PF_SIGNALED;
2463
2464 if (sig_kernel_coredump(signr)) {
2465 if (print_fatal_signals)
2466 print_fatal_signal(ksig->info.si_signo);
2467 proc_coredump_connector(current);
2468 /*
2469 * If it was able to dump core, this kills all
2470 * other threads in the group and synchronizes with
2471 * their demise. If we lost the race with another
2472 * thread getting here, it set group_exit_code
2473 * first and our do_group_exit call below will use
2474 * that value and ignore the one we pass it.
2475 */
2476 do_coredump(&ksig->info);
2477 }
2478
2479 /*
2480 * Death signals, no core dump.
2481 */
2482 do_group_exit(ksig->info.si_signo);
2483 /* NOTREACHED */
2484 }
2485 spin_unlock_irq(&sighand->siglock);
2486
2487 ksig->sig = signr;
2488 return ksig->sig > 0;
2489}
2490
2491/**
2492 * signal_delivered -
2493 * @ksig: kernel signal struct
2494 * @stepping: nonzero if debugger single-step or block-step in use
2495 *
2496 * This function should be called when a signal has successfully been
2497 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2498 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2499 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2500 */
2501static void signal_delivered(struct ksignal *ksig, int stepping)
2502{
2503 sigset_t blocked;
2504
2505 /* A signal was successfully delivered, and the
2506 saved sigmask was stored on the signal frame,
2507 and will be restored by sigreturn. So we can
2508 simply clear the restore sigmask flag. */
2509 clear_restore_sigmask();
2510
2511 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2512 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2513 sigaddset(&blocked, ksig->sig);
2514 set_current_blocked(&blocked);
2515 tracehook_signal_handler(stepping);
2516}
2517
2518void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2519{
2520 if (failed)
2521 force_sigsegv(ksig->sig, current);
2522 else
2523 signal_delivered(ksig, stepping);
2524}
2525
2526/*
2527 * It could be that complete_signal() picked us to notify about the
2528 * group-wide signal. Other threads should be notified now to take
2529 * the shared signals in @which since we will not.
2530 */
2531static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2532{
2533 sigset_t retarget;
2534 struct task_struct *t;
2535
2536 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2537 if (sigisemptyset(&retarget))
2538 return;
2539
2540 t = tsk;
2541 while_each_thread(tsk, t) {
2542 if (t->flags & PF_EXITING)
2543 continue;
2544
2545 if (!has_pending_signals(&retarget, &t->blocked))
2546 continue;
2547 /* Remove the signals this thread can handle. */
2548 sigandsets(&retarget, &retarget, &t->blocked);
2549
2550 if (!signal_pending(t))
2551 signal_wake_up(t, 0);
2552
2553 if (sigisemptyset(&retarget))
2554 break;
2555 }
2556}
2557
2558void exit_signals(struct task_struct *tsk)
2559{
2560 int group_stop = 0;
2561 sigset_t unblocked;
2562
2563 /*
2564 * @tsk is about to have PF_EXITING set - lock out users which
2565 * expect stable threadgroup.
2566 */
2567 cgroup_threadgroup_change_begin(tsk);
2568
2569 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2570 tsk->flags |= PF_EXITING;
2571 cgroup_threadgroup_change_end(tsk);
2572 return;
2573 }
2574
2575 spin_lock_irq(&tsk->sighand->siglock);
2576 /*
2577 * From now this task is not visible for group-wide signals,
2578 * see wants_signal(), do_signal_stop().
2579 */
2580 tsk->flags |= PF_EXITING;
2581
2582 cgroup_threadgroup_change_end(tsk);
2583
2584 if (!signal_pending(tsk))
2585 goto out;
2586
2587 unblocked = tsk->blocked;
2588 signotset(&unblocked);
2589 retarget_shared_pending(tsk, &unblocked);
2590
2591 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2592 task_participate_group_stop(tsk))
2593 group_stop = CLD_STOPPED;
2594out:
2595 spin_unlock_irq(&tsk->sighand->siglock);
2596
2597 /*
2598 * If group stop has completed, deliver the notification. This
2599 * should always go to the real parent of the group leader.
2600 */
2601 if (unlikely(group_stop)) {
2602 read_lock(&tasklist_lock);
2603 do_notify_parent_cldstop(tsk, false, group_stop);
2604 read_unlock(&tasklist_lock);
2605 }
2606}
2607
2608EXPORT_SYMBOL(recalc_sigpending);
2609EXPORT_SYMBOL_GPL(dequeue_signal);
2610EXPORT_SYMBOL(flush_signals);
2611EXPORT_SYMBOL(force_sig);
2612EXPORT_SYMBOL(send_sig);
2613EXPORT_SYMBOL(send_sig_info);
2614EXPORT_SYMBOL(sigprocmask);
2615
2616/*
2617 * System call entry points.
2618 */
2619
2620/**
2621 * sys_restart_syscall - restart a system call
2622 */
2623SYSCALL_DEFINE0(restart_syscall)
2624{
2625 struct restart_block *restart = ¤t->restart_block;
2626 return restart->fn(restart);
2627}
2628
2629long do_no_restart_syscall(struct restart_block *param)
2630{
2631 return -EINTR;
2632}
2633
2634static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2635{
2636 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2637 sigset_t newblocked;
2638 /* A set of now blocked but previously unblocked signals. */
2639 sigandnsets(&newblocked, newset, ¤t->blocked);
2640 retarget_shared_pending(tsk, &newblocked);
2641 }
2642 tsk->blocked = *newset;
2643 recalc_sigpending();
2644}
2645
2646/**
2647 * set_current_blocked - change current->blocked mask
2648 * @newset: new mask
2649 *
2650 * It is wrong to change ->blocked directly, this helper should be used
2651 * to ensure the process can't miss a shared signal we are going to block.
2652 */
2653void set_current_blocked(sigset_t *newset)
2654{
2655 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2656 __set_current_blocked(newset);
2657}
2658
2659void __set_current_blocked(const sigset_t *newset)
2660{
2661 struct task_struct *tsk = current;
2662
2663 /*
2664 * In case the signal mask hasn't changed, there is nothing we need
2665 * to do. The current->blocked shouldn't be modified by other task.
2666 */
2667 if (sigequalsets(&tsk->blocked, newset))
2668 return;
2669
2670 spin_lock_irq(&tsk->sighand->siglock);
2671 __set_task_blocked(tsk, newset);
2672 spin_unlock_irq(&tsk->sighand->siglock);
2673}
2674
2675/*
2676 * This is also useful for kernel threads that want to temporarily
2677 * (or permanently) block certain signals.
2678 *
2679 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2680 * interface happily blocks "unblockable" signals like SIGKILL
2681 * and friends.
2682 */
2683int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2684{
2685 struct task_struct *tsk = current;
2686 sigset_t newset;
2687
2688 /* Lockless, only current can change ->blocked, never from irq */
2689 if (oldset)
2690 *oldset = tsk->blocked;
2691
2692 switch (how) {
2693 case SIG_BLOCK:
2694 sigorsets(&newset, &tsk->blocked, set);
2695 break;
2696 case SIG_UNBLOCK:
2697 sigandnsets(&newset, &tsk->blocked, set);
2698 break;
2699 case SIG_SETMASK:
2700 newset = *set;
2701 break;
2702 default:
2703 return -EINVAL;
2704 }
2705
2706 __set_current_blocked(&newset);
2707 return 0;
2708}
2709
2710/**
2711 * sys_rt_sigprocmask - change the list of currently blocked signals
2712 * @how: whether to add, remove, or set signals
2713 * @nset: stores pending signals
2714 * @oset: previous value of signal mask if non-null
2715 * @sigsetsize: size of sigset_t type
2716 */
2717SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2718 sigset_t __user *, oset, size_t, sigsetsize)
2719{
2720 sigset_t old_set, new_set;
2721 int error;
2722
2723 /* XXX: Don't preclude handling different sized sigset_t's. */
2724 if (sigsetsize != sizeof(sigset_t))
2725 return -EINVAL;
2726
2727 old_set = current->blocked;
2728
2729 if (nset) {
2730 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2731 return -EFAULT;
2732 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2733
2734 error = sigprocmask(how, &new_set, NULL);
2735 if (error)
2736 return error;
2737 }
2738
2739 if (oset) {
2740 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2741 return -EFAULT;
2742 }
2743
2744 return 0;
2745}
2746
2747#ifdef CONFIG_COMPAT
2748COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2749 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2750{
2751 sigset_t old_set = current->blocked;
2752
2753 /* XXX: Don't preclude handling different sized sigset_t's. */
2754 if (sigsetsize != sizeof(sigset_t))
2755 return -EINVAL;
2756
2757 if (nset) {
2758 sigset_t new_set;
2759 int error;
2760 if (get_compat_sigset(&new_set, nset))
2761 return -EFAULT;
2762 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2763
2764 error = sigprocmask(how, &new_set, NULL);
2765 if (error)
2766 return error;
2767 }
2768 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
2769}
2770#endif
2771
2772static int do_sigpending(sigset_t *set)
2773{
2774 spin_lock_irq(¤t->sighand->siglock);
2775 sigorsets(set, ¤t->pending.signal,
2776 ¤t->signal->shared_pending.signal);
2777 spin_unlock_irq(¤t->sighand->siglock);
2778
2779 /* Outside the lock because only this thread touches it. */
2780 sigandsets(set, ¤t->blocked, set);
2781 return 0;
2782}
2783
2784/**
2785 * sys_rt_sigpending - examine a pending signal that has been raised
2786 * while blocked
2787 * @uset: stores pending signals
2788 * @sigsetsize: size of sigset_t type or larger
2789 */
2790SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2791{
2792 sigset_t set;
2793 int err;
2794
2795 if (sigsetsize > sizeof(*uset))
2796 return -EINVAL;
2797
2798 err = do_sigpending(&set);
2799 if (!err && copy_to_user(uset, &set, sigsetsize))
2800 err = -EFAULT;
2801 return err;
2802}
2803
2804#ifdef CONFIG_COMPAT
2805COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2806 compat_size_t, sigsetsize)
2807{
2808 sigset_t set;
2809 int err;
2810
2811 if (sigsetsize > sizeof(*uset))
2812 return -EINVAL;
2813
2814 err = do_sigpending(&set);
2815 if (!err)
2816 err = put_compat_sigset(uset, &set, sigsetsize);
2817 return err;
2818}
2819#endif
2820
2821enum siginfo_layout siginfo_layout(int sig, int si_code)
2822{
2823 enum siginfo_layout layout = SIL_KILL;
2824 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
2825 static const struct {
2826 unsigned char limit, layout;
2827 } filter[] = {
2828 [SIGILL] = { NSIGILL, SIL_FAULT },
2829 [SIGFPE] = { NSIGFPE, SIL_FAULT },
2830 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
2831 [SIGBUS] = { NSIGBUS, SIL_FAULT },
2832 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
2833#if defined(SIGEMT) && defined(NSIGEMT)
2834 [SIGEMT] = { NSIGEMT, SIL_FAULT },
2835#endif
2836 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
2837 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
2838 [SIGSYS] = { NSIGSYS, SIL_SYS },
2839 };
2840 if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit))
2841 layout = filter[sig].layout;
2842 else if (si_code <= NSIGPOLL)
2843 layout = SIL_POLL;
2844 } else {
2845 if (si_code == SI_TIMER)
2846 layout = SIL_TIMER;
2847 else if (si_code == SI_SIGIO)
2848 layout = SIL_POLL;
2849 else if (si_code < 0)
2850 layout = SIL_RT;
2851 /* Tests to support buggy kernel ABIs */
2852#ifdef TRAP_FIXME
2853 if ((sig == SIGTRAP) && (si_code == TRAP_FIXME))
2854 layout = SIL_FAULT;
2855#endif
2856#ifdef FPE_FIXME
2857 if ((sig == SIGFPE) && (si_code == FPE_FIXME))
2858 layout = SIL_FAULT;
2859#endif
2860 }
2861 return layout;
2862}
2863
2864int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2865{
2866 int err;
2867
2868 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2869 return -EFAULT;
2870 if (from->si_code < 0)
2871 return __copy_to_user(to, from, sizeof(siginfo_t))
2872 ? -EFAULT : 0;
2873 /*
2874 * If you change siginfo_t structure, please be sure
2875 * this code is fixed accordingly.
2876 * Please remember to update the signalfd_copyinfo() function
2877 * inside fs/signalfd.c too, in case siginfo_t changes.
2878 * It should never copy any pad contained in the structure
2879 * to avoid security leaks, but must copy the generic
2880 * 3 ints plus the relevant union member.
2881 */
2882 err = __put_user(from->si_signo, &to->si_signo);
2883 err |= __put_user(from->si_errno, &to->si_errno);
2884 err |= __put_user(from->si_code, &to->si_code);
2885 switch (siginfo_layout(from->si_signo, from->si_code)) {
2886 case SIL_KILL:
2887 err |= __put_user(from->si_pid, &to->si_pid);
2888 err |= __put_user(from->si_uid, &to->si_uid);
2889 break;
2890 case SIL_TIMER:
2891 /* Unreached SI_TIMER is negative */
2892 break;
2893 case SIL_POLL:
2894 err |= __put_user(from->si_band, &to->si_band);
2895 err |= __put_user(from->si_fd, &to->si_fd);
2896 break;
2897 case SIL_FAULT:
2898 err |= __put_user(from->si_addr, &to->si_addr);
2899#ifdef __ARCH_SI_TRAPNO
2900 err |= __put_user(from->si_trapno, &to->si_trapno);
2901#endif
2902#ifdef __ia64__
2903 err |= __put_user(from->si_imm, &to->si_imm);
2904 err |= __put_user(from->si_flags, &to->si_flags);
2905 err |= __put_user(from->si_isr, &to->si_isr);
2906#endif
2907 /*
2908 * Other callers might not initialize the si_lsb field,
2909 * so check explicitly for the right codes here.
2910 */
2911#ifdef BUS_MCEERR_AR
2912 if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AR)
2913 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2914#endif
2915#ifdef BUS_MCEERR_AO
2916 if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AO)
2917 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2918#endif
2919#ifdef SEGV_BNDERR
2920 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2921 err |= __put_user(from->si_lower, &to->si_lower);
2922 err |= __put_user(from->si_upper, &to->si_upper);
2923 }
2924#endif
2925#ifdef SEGV_PKUERR
2926 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2927 err |= __put_user(from->si_pkey, &to->si_pkey);
2928#endif
2929 break;
2930 case SIL_CHLD:
2931 err |= __put_user(from->si_pid, &to->si_pid);
2932 err |= __put_user(from->si_uid, &to->si_uid);
2933 err |= __put_user(from->si_status, &to->si_status);
2934 err |= __put_user(from->si_utime, &to->si_utime);
2935 err |= __put_user(from->si_stime, &to->si_stime);
2936 break;
2937 case SIL_RT:
2938 err |= __put_user(from->si_pid, &to->si_pid);
2939 err |= __put_user(from->si_uid, &to->si_uid);
2940 err |= __put_user(from->si_ptr, &to->si_ptr);
2941 break;
2942 case SIL_SYS:
2943 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2944 err |= __put_user(from->si_syscall, &to->si_syscall);
2945 err |= __put_user(from->si_arch, &to->si_arch);
2946 break;
2947 }
2948 return err;
2949}
2950
2951#ifdef CONFIG_COMPAT
2952int copy_siginfo_to_user32(struct compat_siginfo __user *to,
2953 const struct siginfo *from)
2954#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
2955{
2956 return __copy_siginfo_to_user32(to, from, in_x32_syscall());
2957}
2958int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
2959 const struct siginfo *from, bool x32_ABI)
2960#endif
2961{
2962 struct compat_siginfo new;
2963 memset(&new, 0, sizeof(new));
2964
2965 new.si_signo = from->si_signo;
2966 new.si_errno = from->si_errno;
2967 new.si_code = from->si_code;
2968 switch(siginfo_layout(from->si_signo, from->si_code)) {
2969 case SIL_KILL:
2970 new.si_pid = from->si_pid;
2971 new.si_uid = from->si_uid;
2972 break;
2973 case SIL_TIMER:
2974 new.si_tid = from->si_tid;
2975 new.si_overrun = from->si_overrun;
2976 new.si_int = from->si_int;
2977 break;
2978 case SIL_POLL:
2979 new.si_band = from->si_band;
2980 new.si_fd = from->si_fd;
2981 break;
2982 case SIL_FAULT:
2983 new.si_addr = ptr_to_compat(from->si_addr);
2984#ifdef __ARCH_SI_TRAPNO
2985 new.si_trapno = from->si_trapno;
2986#endif
2987#ifdef BUS_MCEERR_AR
2988 if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AR))
2989 new.si_addr_lsb = from->si_addr_lsb;
2990#endif
2991#ifdef BUS_MCEERR_AO
2992 if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AO))
2993 new.si_addr_lsb = from->si_addr_lsb;
2994#endif
2995#ifdef SEGV_BNDERR
2996 if ((from->si_signo == SIGSEGV) &&
2997 (from->si_code == SEGV_BNDERR)) {
2998 new.si_lower = ptr_to_compat(from->si_lower);
2999 new.si_upper = ptr_to_compat(from->si_upper);
3000 }
3001#endif
3002#ifdef SEGV_PKUERR
3003 if ((from->si_signo == SIGSEGV) &&
3004 (from->si_code == SEGV_PKUERR))
3005 new.si_pkey = from->si_pkey;
3006#endif
3007
3008 break;
3009 case SIL_CHLD:
3010 new.si_pid = from->si_pid;
3011 new.si_uid = from->si_uid;
3012 new.si_status = from->si_status;
3013#ifdef CONFIG_X86_X32_ABI
3014 if (x32_ABI) {
3015 new._sifields._sigchld_x32._utime = from->si_utime;
3016 new._sifields._sigchld_x32._stime = from->si_stime;
3017 } else
3018#endif
3019 {
3020 new.si_utime = from->si_utime;
3021 new.si_stime = from->si_stime;
3022 }
3023 break;
3024 case SIL_RT:
3025 new.si_pid = from->si_pid;
3026 new.si_uid = from->si_uid;
3027 new.si_int = from->si_int;
3028 break;
3029 case SIL_SYS:
3030 new.si_call_addr = ptr_to_compat(from->si_call_addr);
3031 new.si_syscall = from->si_syscall;
3032 new.si_arch = from->si_arch;
3033 break;
3034 }
3035
3036 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3037 return -EFAULT;
3038
3039 return 0;
3040}
3041
3042int copy_siginfo_from_user32(struct siginfo *to,
3043 const struct compat_siginfo __user *ufrom)
3044{
3045 struct compat_siginfo from;
3046
3047 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3048 return -EFAULT;
3049
3050 clear_siginfo(to);
3051 to->si_signo = from.si_signo;
3052 to->si_errno = from.si_errno;
3053 to->si_code = from.si_code;
3054 switch(siginfo_layout(from.si_signo, from.si_code)) {
3055 case SIL_KILL:
3056 to->si_pid = from.si_pid;
3057 to->si_uid = from.si_uid;
3058 break;
3059 case SIL_TIMER:
3060 to->si_tid = from.si_tid;
3061 to->si_overrun = from.si_overrun;
3062 to->si_int = from.si_int;
3063 break;
3064 case SIL_POLL:
3065 to->si_band = from.si_band;
3066 to->si_fd = from.si_fd;
3067 break;
3068 case SIL_FAULT:
3069 to->si_addr = compat_ptr(from.si_addr);
3070#ifdef __ARCH_SI_TRAPNO
3071 to->si_trapno = from.si_trapno;
3072#endif
3073#ifdef BUS_MCEERR_AR
3074 if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AR))
3075 to->si_addr_lsb = from.si_addr_lsb;
3076#endif
3077#ifdef BUS_MCEER_AO
3078 if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AO))
3079 to->si_addr_lsb = from.si_addr_lsb;
3080#endif
3081#ifdef SEGV_BNDERR
3082 if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) {
3083 to->si_lower = compat_ptr(from.si_lower);
3084 to->si_upper = compat_ptr(from.si_upper);
3085 }
3086#endif
3087#ifdef SEGV_PKUERR
3088 if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR))
3089 to->si_pkey = from.si_pkey;
3090#endif
3091 break;
3092 case SIL_CHLD:
3093 to->si_pid = from.si_pid;
3094 to->si_uid = from.si_uid;
3095 to->si_status = from.si_status;
3096#ifdef CONFIG_X86_X32_ABI
3097 if (in_x32_syscall()) {
3098 to->si_utime = from._sifields._sigchld_x32._utime;
3099 to->si_stime = from._sifields._sigchld_x32._stime;
3100 } else
3101#endif
3102 {
3103 to->si_utime = from.si_utime;
3104 to->si_stime = from.si_stime;
3105 }
3106 break;
3107 case SIL_RT:
3108 to->si_pid = from.si_pid;
3109 to->si_uid = from.si_uid;
3110 to->si_int = from.si_int;
3111 break;
3112 case SIL_SYS:
3113 to->si_call_addr = compat_ptr(from.si_call_addr);
3114 to->si_syscall = from.si_syscall;
3115 to->si_arch = from.si_arch;
3116 break;
3117 }
3118 return 0;
3119}
3120#endif /* CONFIG_COMPAT */
3121
3122/**
3123 * do_sigtimedwait - wait for queued signals specified in @which
3124 * @which: queued signals to wait for
3125 * @info: if non-null, the signal's siginfo is returned here
3126 * @ts: upper bound on process time suspension
3127 */
3128static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
3129 const struct timespec *ts)
3130{
3131 ktime_t *to = NULL, timeout = KTIME_MAX;
3132 struct task_struct *tsk = current;
3133 sigset_t mask = *which;
3134 int sig, ret = 0;
3135
3136 if (ts) {
3137 if (!timespec_valid(ts))
3138 return -EINVAL;
3139 timeout = timespec_to_ktime(*ts);
3140 to = &timeout;
3141 }
3142
3143 /*
3144 * Invert the set of allowed signals to get those we want to block.
3145 */
3146 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3147 signotset(&mask);
3148
3149 spin_lock_irq(&tsk->sighand->siglock);
3150 sig = dequeue_signal(tsk, &mask, info);
3151 if (!sig && timeout) {
3152 /*
3153 * None ready, temporarily unblock those we're interested
3154 * while we are sleeping in so that we'll be awakened when
3155 * they arrive. Unblocking is always fine, we can avoid
3156 * set_current_blocked().
3157 */
3158 tsk->real_blocked = tsk->blocked;
3159 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3160 recalc_sigpending();
3161 spin_unlock_irq(&tsk->sighand->siglock);
3162
3163 __set_current_state(TASK_INTERRUPTIBLE);
3164 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3165 HRTIMER_MODE_REL);
3166 spin_lock_irq(&tsk->sighand->siglock);
3167 __set_task_blocked(tsk, &tsk->real_blocked);
3168 sigemptyset(&tsk->real_blocked);
3169 sig = dequeue_signal(tsk, &mask, info);
3170 }
3171 spin_unlock_irq(&tsk->sighand->siglock);
3172
3173 if (sig)
3174 return sig;
3175 return ret ? -EINTR : -EAGAIN;
3176}
3177
3178/**
3179 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3180 * in @uthese
3181 * @uthese: queued signals to wait for
3182 * @uinfo: if non-null, the signal's siginfo is returned here
3183 * @uts: upper bound on process time suspension
3184 * @sigsetsize: size of sigset_t type
3185 */
3186SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3187 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
3188 size_t, sigsetsize)
3189{
3190 sigset_t these;
3191 struct timespec ts;
3192 siginfo_t info;
3193 int ret;
3194
3195 /* XXX: Don't preclude handling different sized sigset_t's. */
3196 if (sigsetsize != sizeof(sigset_t))
3197 return -EINVAL;
3198
3199 if (copy_from_user(&these, uthese, sizeof(these)))
3200 return -EFAULT;
3201
3202 if (uts) {
3203 if (copy_from_user(&ts, uts, sizeof(ts)))
3204 return -EFAULT;
3205 }
3206
3207 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3208
3209 if (ret > 0 && uinfo) {
3210 if (copy_siginfo_to_user(uinfo, &info))
3211 ret = -EFAULT;
3212 }
3213
3214 return ret;
3215}
3216
3217#ifdef CONFIG_COMPAT
3218COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
3219 struct compat_siginfo __user *, uinfo,
3220 struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
3221{
3222 sigset_t s;
3223 struct timespec t;
3224 siginfo_t info;
3225 long ret;
3226
3227 if (sigsetsize != sizeof(sigset_t))
3228 return -EINVAL;
3229
3230 if (get_compat_sigset(&s, uthese))
3231 return -EFAULT;
3232
3233 if (uts) {
3234 if (compat_get_timespec(&t, uts))
3235 return -EFAULT;
3236 }
3237
3238 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3239
3240 if (ret > 0 && uinfo) {
3241 if (copy_siginfo_to_user32(uinfo, &info))
3242 ret = -EFAULT;
3243 }
3244
3245 return ret;
3246}
3247#endif
3248
3249/**
3250 * sys_kill - send a signal to a process
3251 * @pid: the PID of the process
3252 * @sig: signal to be sent
3253 */
3254SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3255{
3256 struct siginfo info;
3257
3258 clear_siginfo(&info);
3259 info.si_signo = sig;
3260 info.si_errno = 0;
3261 info.si_code = SI_USER;
3262 info.si_pid = task_tgid_vnr(current);
3263 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3264
3265 return kill_something_info(sig, &info, pid);
3266}
3267
3268static int
3269do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
3270{
3271 struct task_struct *p;
3272 int error = -ESRCH;
3273
3274 rcu_read_lock();
3275 p = find_task_by_vpid(pid);
3276 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3277 error = check_kill_permission(sig, info, p);
3278 /*
3279 * The null signal is a permissions and process existence
3280 * probe. No signal is actually delivered.
3281 */
3282 if (!error && sig) {
3283 error = do_send_sig_info(sig, info, p, false);
3284 /*
3285 * If lock_task_sighand() failed we pretend the task
3286 * dies after receiving the signal. The window is tiny,
3287 * and the signal is private anyway.
3288 */
3289 if (unlikely(error == -ESRCH))
3290 error = 0;
3291 }
3292 }
3293 rcu_read_unlock();
3294
3295 return error;
3296}
3297
3298static int do_tkill(pid_t tgid, pid_t pid, int sig)
3299{
3300 struct siginfo info;
3301
3302 clear_siginfo(&info);
3303 info.si_signo = sig;
3304 info.si_errno = 0;
3305 info.si_code = SI_TKILL;
3306 info.si_pid = task_tgid_vnr(current);
3307 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3308
3309 return do_send_specific(tgid, pid, sig, &info);
3310}
3311
3312/**
3313 * sys_tgkill - send signal to one specific thread
3314 * @tgid: the thread group ID of the thread
3315 * @pid: the PID of the thread
3316 * @sig: signal to be sent
3317 *
3318 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3319 * exists but it's not belonging to the target process anymore. This
3320 * method solves the problem of threads exiting and PIDs getting reused.
3321 */
3322SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3323{
3324 /* This is only valid for single tasks */
3325 if (pid <= 0 || tgid <= 0)
3326 return -EINVAL;
3327
3328 return do_tkill(tgid, pid, sig);
3329}
3330
3331/**
3332 * sys_tkill - send signal to one specific task
3333 * @pid: the PID of the task
3334 * @sig: signal to be sent
3335 *
3336 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3337 */
3338SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3339{
3340 /* This is only valid for single tasks */
3341 if (pid <= 0)
3342 return -EINVAL;
3343
3344 return do_tkill(0, pid, sig);
3345}
3346
3347static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3348{
3349 /* Not even root can pretend to send signals from the kernel.
3350 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3351 */
3352 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3353 (task_pid_vnr(current) != pid))
3354 return -EPERM;
3355
3356 info->si_signo = sig;
3357
3358 /* POSIX.1b doesn't mention process groups. */
3359 return kill_proc_info(sig, info, pid);
3360}
3361
3362/**
3363 * sys_rt_sigqueueinfo - send signal information to a signal
3364 * @pid: the PID of the thread
3365 * @sig: signal to be sent
3366 * @uinfo: signal info to be sent
3367 */
3368SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3369 siginfo_t __user *, uinfo)
3370{
3371 siginfo_t info;
3372 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3373 return -EFAULT;
3374 return do_rt_sigqueueinfo(pid, sig, &info);
3375}
3376
3377#ifdef CONFIG_COMPAT
3378COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3379 compat_pid_t, pid,
3380 int, sig,
3381 struct compat_siginfo __user *, uinfo)
3382{
3383 siginfo_t info;
3384 int ret = copy_siginfo_from_user32(&info, uinfo);
3385 if (unlikely(ret))
3386 return ret;
3387 return do_rt_sigqueueinfo(pid, sig, &info);
3388}
3389#endif
3390
3391static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3392{
3393 /* This is only valid for single tasks */
3394 if (pid <= 0 || tgid <= 0)
3395 return -EINVAL;
3396
3397 /* Not even root can pretend to send signals from the kernel.
3398 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3399 */
3400 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3401 (task_pid_vnr(current) != pid))
3402 return -EPERM;
3403
3404 info->si_signo = sig;
3405
3406 return do_send_specific(tgid, pid, sig, info);
3407}
3408
3409SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3410 siginfo_t __user *, uinfo)
3411{
3412 siginfo_t info;
3413
3414 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3415 return -EFAULT;
3416
3417 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3418}
3419
3420#ifdef CONFIG_COMPAT
3421COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3422 compat_pid_t, tgid,
3423 compat_pid_t, pid,
3424 int, sig,
3425 struct compat_siginfo __user *, uinfo)
3426{
3427 siginfo_t info;
3428
3429 if (copy_siginfo_from_user32(&info, uinfo))
3430 return -EFAULT;
3431 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3432}
3433#endif
3434
3435/*
3436 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3437 */
3438void kernel_sigaction(int sig, __sighandler_t action)
3439{
3440 spin_lock_irq(¤t->sighand->siglock);
3441 current->sighand->action[sig - 1].sa.sa_handler = action;
3442 if (action == SIG_IGN) {
3443 sigset_t mask;
3444
3445 sigemptyset(&mask);
3446 sigaddset(&mask, sig);
3447
3448 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3449 flush_sigqueue_mask(&mask, ¤t->pending);
3450 recalc_sigpending();
3451 }
3452 spin_unlock_irq(¤t->sighand->siglock);
3453}
3454EXPORT_SYMBOL(kernel_sigaction);
3455
3456void __weak sigaction_compat_abi(struct k_sigaction *act,
3457 struct k_sigaction *oact)
3458{
3459}
3460
3461int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3462{
3463 struct task_struct *p = current, *t;
3464 struct k_sigaction *k;
3465 sigset_t mask;
3466
3467 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3468 return -EINVAL;
3469
3470 k = &p->sighand->action[sig-1];
3471
3472 spin_lock_irq(&p->sighand->siglock);
3473 if (oact)
3474 *oact = *k;
3475
3476 sigaction_compat_abi(act, oact);
3477
3478 if (act) {
3479 sigdelsetmask(&act->sa.sa_mask,
3480 sigmask(SIGKILL) | sigmask(SIGSTOP));
3481 *k = *act;
3482 /*
3483 * POSIX 3.3.1.3:
3484 * "Setting a signal action to SIG_IGN for a signal that is
3485 * pending shall cause the pending signal to be discarded,
3486 * whether or not it is blocked."
3487 *
3488 * "Setting a signal action to SIG_DFL for a signal that is
3489 * pending and whose default action is to ignore the signal
3490 * (for example, SIGCHLD), shall cause the pending signal to
3491 * be discarded, whether or not it is blocked"
3492 */
3493 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3494 sigemptyset(&mask);
3495 sigaddset(&mask, sig);
3496 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3497 for_each_thread(p, t)
3498 flush_sigqueue_mask(&mask, &t->pending);
3499 }
3500 }
3501
3502 spin_unlock_irq(&p->sighand->siglock);
3503 return 0;
3504}
3505
3506static int
3507do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
3508{
3509 struct task_struct *t = current;
3510
3511 if (oss) {
3512 memset(oss, 0, sizeof(stack_t));
3513 oss->ss_sp = (void __user *) t->sas_ss_sp;
3514 oss->ss_size = t->sas_ss_size;
3515 oss->ss_flags = sas_ss_flags(sp) |
3516 (current->sas_ss_flags & SS_FLAG_BITS);
3517 }
3518
3519 if (ss) {
3520 void __user *ss_sp = ss->ss_sp;
3521 size_t ss_size = ss->ss_size;
3522 unsigned ss_flags = ss->ss_flags;
3523 int ss_mode;
3524
3525 if (unlikely(on_sig_stack(sp)))
3526 return -EPERM;
3527
3528 ss_mode = ss_flags & ~SS_FLAG_BITS;
3529 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3530 ss_mode != 0))
3531 return -EINVAL;
3532
3533 if (ss_mode == SS_DISABLE) {
3534 ss_size = 0;
3535 ss_sp = NULL;
3536 } else {
3537 if (unlikely(ss_size < MINSIGSTKSZ))
3538 return -ENOMEM;
3539 }
3540
3541 t->sas_ss_sp = (unsigned long) ss_sp;
3542 t->sas_ss_size = ss_size;
3543 t->sas_ss_flags = ss_flags;
3544 }
3545 return 0;
3546}
3547
3548SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3549{
3550 stack_t new, old;
3551 int err;
3552 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
3553 return -EFAULT;
3554 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
3555 current_user_stack_pointer());
3556 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
3557 err = -EFAULT;
3558 return err;
3559}
3560
3561int restore_altstack(const stack_t __user *uss)
3562{
3563 stack_t new;
3564 if (copy_from_user(&new, uss, sizeof(stack_t)))
3565 return -EFAULT;
3566 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
3567 /* squash all but EFAULT for now */
3568 return 0;
3569}
3570
3571int __save_altstack(stack_t __user *uss, unsigned long sp)
3572{
3573 struct task_struct *t = current;
3574 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3575 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3576 __put_user(t->sas_ss_size, &uss->ss_size);
3577 if (err)
3578 return err;
3579 if (t->sas_ss_flags & SS_AUTODISARM)
3580 sas_ss_reset(t);
3581 return 0;
3582}
3583
3584#ifdef CONFIG_COMPAT
3585static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
3586 compat_stack_t __user *uoss_ptr)
3587{
3588 stack_t uss, uoss;
3589 int ret;
3590
3591 if (uss_ptr) {
3592 compat_stack_t uss32;
3593 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3594 return -EFAULT;
3595 uss.ss_sp = compat_ptr(uss32.ss_sp);
3596 uss.ss_flags = uss32.ss_flags;
3597 uss.ss_size = uss32.ss_size;
3598 }
3599 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
3600 compat_user_stack_pointer());
3601 if (ret >= 0 && uoss_ptr) {
3602 compat_stack_t old;
3603 memset(&old, 0, sizeof(old));
3604 old.ss_sp = ptr_to_compat(uoss.ss_sp);
3605 old.ss_flags = uoss.ss_flags;
3606 old.ss_size = uoss.ss_size;
3607 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
3608 ret = -EFAULT;
3609 }
3610 return ret;
3611}
3612
3613COMPAT_SYSCALL_DEFINE2(sigaltstack,
3614 const compat_stack_t __user *, uss_ptr,
3615 compat_stack_t __user *, uoss_ptr)
3616{
3617 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
3618}
3619
3620int compat_restore_altstack(const compat_stack_t __user *uss)
3621{
3622 int err = do_compat_sigaltstack(uss, NULL);
3623 /* squash all but -EFAULT for now */
3624 return err == -EFAULT ? err : 0;
3625}
3626
3627int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3628{
3629 int err;
3630 struct task_struct *t = current;
3631 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3632 &uss->ss_sp) |
3633 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3634 __put_user(t->sas_ss_size, &uss->ss_size);
3635 if (err)
3636 return err;
3637 if (t->sas_ss_flags & SS_AUTODISARM)
3638 sas_ss_reset(t);
3639 return 0;
3640}
3641#endif
3642
3643#ifdef __ARCH_WANT_SYS_SIGPENDING
3644
3645/**
3646 * sys_sigpending - examine pending signals
3647 * @uset: where mask of pending signal is returned
3648 */
3649SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
3650{
3651 sigset_t set;
3652 int err;
3653
3654 if (sizeof(old_sigset_t) > sizeof(*uset))
3655 return -EINVAL;
3656
3657 err = do_sigpending(&set);
3658 if (!err && copy_to_user(uset, &set, sizeof(old_sigset_t)))
3659 err = -EFAULT;
3660 return err;
3661}
3662
3663#ifdef CONFIG_COMPAT
3664COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
3665{
3666 sigset_t set;
3667 int err = do_sigpending(&set);
3668 if (!err)
3669 err = put_user(set.sig[0], set32);
3670 return err;
3671}
3672#endif
3673
3674#endif
3675
3676#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3677/**
3678 * sys_sigprocmask - examine and change blocked signals
3679 * @how: whether to add, remove, or set signals
3680 * @nset: signals to add or remove (if non-null)
3681 * @oset: previous value of signal mask if non-null
3682 *
3683 * Some platforms have their own version with special arguments;
3684 * others support only sys_rt_sigprocmask.
3685 */
3686
3687SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3688 old_sigset_t __user *, oset)
3689{
3690 old_sigset_t old_set, new_set;
3691 sigset_t new_blocked;
3692
3693 old_set = current->blocked.sig[0];
3694
3695 if (nset) {
3696 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3697 return -EFAULT;
3698
3699 new_blocked = current->blocked;
3700
3701 switch (how) {
3702 case SIG_BLOCK:
3703 sigaddsetmask(&new_blocked, new_set);
3704 break;
3705 case SIG_UNBLOCK:
3706 sigdelsetmask(&new_blocked, new_set);
3707 break;
3708 case SIG_SETMASK:
3709 new_blocked.sig[0] = new_set;
3710 break;
3711 default:
3712 return -EINVAL;
3713 }
3714
3715 set_current_blocked(&new_blocked);
3716 }
3717
3718 if (oset) {
3719 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3720 return -EFAULT;
3721 }
3722
3723 return 0;
3724}
3725#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3726
3727#ifndef CONFIG_ODD_RT_SIGACTION
3728/**
3729 * sys_rt_sigaction - alter an action taken by a process
3730 * @sig: signal to be sent
3731 * @act: new sigaction
3732 * @oact: used to save the previous sigaction
3733 * @sigsetsize: size of sigset_t type
3734 */
3735SYSCALL_DEFINE4(rt_sigaction, int, sig,
3736 const struct sigaction __user *, act,
3737 struct sigaction __user *, oact,
3738 size_t, sigsetsize)
3739{
3740 struct k_sigaction new_sa, old_sa;
3741 int ret = -EINVAL;
3742
3743 /* XXX: Don't preclude handling different sized sigset_t's. */
3744 if (sigsetsize != sizeof(sigset_t))
3745 goto out;
3746
3747 if (act) {
3748 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3749 return -EFAULT;
3750 }
3751
3752 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3753
3754 if (!ret && oact) {
3755 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3756 return -EFAULT;
3757 }
3758out:
3759 return ret;
3760}
3761#ifdef CONFIG_COMPAT
3762COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3763 const struct compat_sigaction __user *, act,
3764 struct compat_sigaction __user *, oact,
3765 compat_size_t, sigsetsize)
3766{
3767 struct k_sigaction new_ka, old_ka;
3768#ifdef __ARCH_HAS_SA_RESTORER
3769 compat_uptr_t restorer;
3770#endif
3771 int ret;
3772
3773 /* XXX: Don't preclude handling different sized sigset_t's. */
3774 if (sigsetsize != sizeof(compat_sigset_t))
3775 return -EINVAL;
3776
3777 if (act) {
3778 compat_uptr_t handler;
3779 ret = get_user(handler, &act->sa_handler);
3780 new_ka.sa.sa_handler = compat_ptr(handler);
3781#ifdef __ARCH_HAS_SA_RESTORER
3782 ret |= get_user(restorer, &act->sa_restorer);
3783 new_ka.sa.sa_restorer = compat_ptr(restorer);
3784#endif
3785 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
3786 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3787 if (ret)
3788 return -EFAULT;
3789 }
3790
3791 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3792 if (!ret && oact) {
3793 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3794 &oact->sa_handler);
3795 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
3796 sizeof(oact->sa_mask));
3797 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3798#ifdef __ARCH_HAS_SA_RESTORER
3799 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3800 &oact->sa_restorer);
3801#endif
3802 }
3803 return ret;
3804}
3805#endif
3806#endif /* !CONFIG_ODD_RT_SIGACTION */
3807
3808#ifdef CONFIG_OLD_SIGACTION
3809SYSCALL_DEFINE3(sigaction, int, sig,
3810 const struct old_sigaction __user *, act,
3811 struct old_sigaction __user *, oact)
3812{
3813 struct k_sigaction new_ka, old_ka;
3814 int ret;
3815
3816 if (act) {
3817 old_sigset_t mask;
3818 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3819 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3820 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3821 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3822 __get_user(mask, &act->sa_mask))
3823 return -EFAULT;
3824#ifdef __ARCH_HAS_KA_RESTORER
3825 new_ka.ka_restorer = NULL;
3826#endif
3827 siginitset(&new_ka.sa.sa_mask, mask);
3828 }
3829
3830 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3831
3832 if (!ret && oact) {
3833 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3834 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3835 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3836 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3837 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3838 return -EFAULT;
3839 }
3840
3841 return ret;
3842}
3843#endif
3844#ifdef CONFIG_COMPAT_OLD_SIGACTION
3845COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3846 const struct compat_old_sigaction __user *, act,
3847 struct compat_old_sigaction __user *, oact)
3848{
3849 struct k_sigaction new_ka, old_ka;
3850 int ret;
3851 compat_old_sigset_t mask;
3852 compat_uptr_t handler, restorer;
3853
3854 if (act) {
3855 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3856 __get_user(handler, &act->sa_handler) ||
3857 __get_user(restorer, &act->sa_restorer) ||
3858 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3859 __get_user(mask, &act->sa_mask))
3860 return -EFAULT;
3861
3862#ifdef __ARCH_HAS_KA_RESTORER
3863 new_ka.ka_restorer = NULL;
3864#endif
3865 new_ka.sa.sa_handler = compat_ptr(handler);
3866 new_ka.sa.sa_restorer = compat_ptr(restorer);
3867 siginitset(&new_ka.sa.sa_mask, mask);
3868 }
3869
3870 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3871
3872 if (!ret && oact) {
3873 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3874 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3875 &oact->sa_handler) ||
3876 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3877 &oact->sa_restorer) ||
3878 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3879 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3880 return -EFAULT;
3881 }
3882 return ret;
3883}
3884#endif
3885
3886#ifdef CONFIG_SGETMASK_SYSCALL
3887
3888/*
3889 * For backwards compatibility. Functionality superseded by sigprocmask.
3890 */
3891SYSCALL_DEFINE0(sgetmask)
3892{
3893 /* SMP safe */
3894 return current->blocked.sig[0];
3895}
3896
3897SYSCALL_DEFINE1(ssetmask, int, newmask)
3898{
3899 int old = current->blocked.sig[0];
3900 sigset_t newset;
3901
3902 siginitset(&newset, newmask);
3903 set_current_blocked(&newset);
3904
3905 return old;
3906}
3907#endif /* CONFIG_SGETMASK_SYSCALL */
3908
3909#ifdef __ARCH_WANT_SYS_SIGNAL
3910/*
3911 * For backwards compatibility. Functionality superseded by sigaction.
3912 */
3913SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3914{
3915 struct k_sigaction new_sa, old_sa;
3916 int ret;
3917
3918 new_sa.sa.sa_handler = handler;
3919 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3920 sigemptyset(&new_sa.sa.sa_mask);
3921
3922 ret = do_sigaction(sig, &new_sa, &old_sa);
3923
3924 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3925}
3926#endif /* __ARCH_WANT_SYS_SIGNAL */
3927
3928#ifdef __ARCH_WANT_SYS_PAUSE
3929
3930SYSCALL_DEFINE0(pause)
3931{
3932 while (!signal_pending(current)) {
3933 __set_current_state(TASK_INTERRUPTIBLE);
3934 schedule();
3935 }
3936 return -ERESTARTNOHAND;
3937}
3938
3939#endif
3940
3941static int sigsuspend(sigset_t *set)
3942{
3943 current->saved_sigmask = current->blocked;
3944 set_current_blocked(set);
3945
3946 while (!signal_pending(current)) {
3947 __set_current_state(TASK_INTERRUPTIBLE);
3948 schedule();
3949 }
3950 set_restore_sigmask();
3951 return -ERESTARTNOHAND;
3952}
3953
3954/**
3955 * sys_rt_sigsuspend - replace the signal mask for a value with the
3956 * @unewset value until a signal is received
3957 * @unewset: new signal mask value
3958 * @sigsetsize: size of sigset_t type
3959 */
3960SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3961{
3962 sigset_t newset;
3963
3964 /* XXX: Don't preclude handling different sized sigset_t's. */
3965 if (sigsetsize != sizeof(sigset_t))
3966 return -EINVAL;
3967
3968 if (copy_from_user(&newset, unewset, sizeof(newset)))
3969 return -EFAULT;
3970 return sigsuspend(&newset);
3971}
3972
3973#ifdef CONFIG_COMPAT
3974COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3975{
3976 sigset_t newset;
3977
3978 /* XXX: Don't preclude handling different sized sigset_t's. */
3979 if (sigsetsize != sizeof(sigset_t))
3980 return -EINVAL;
3981
3982 if (get_compat_sigset(&newset, unewset))
3983 return -EFAULT;
3984 return sigsuspend(&newset);
3985}
3986#endif
3987
3988#ifdef CONFIG_OLD_SIGSUSPEND
3989SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3990{
3991 sigset_t blocked;
3992 siginitset(&blocked, mask);
3993 return sigsuspend(&blocked);
3994}
3995#endif
3996#ifdef CONFIG_OLD_SIGSUSPEND3
3997SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3998{
3999 sigset_t blocked;
4000 siginitset(&blocked, mask);
4001 return sigsuspend(&blocked);
4002}
4003#endif
4004
4005__weak const char *arch_vma_name(struct vm_area_struct *vma)
4006{
4007 return NULL;
4008}
4009
4010void __init signals_init(void)
4011{
4012 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
4013 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
4014 != offsetof(struct siginfo, _sifields._pad));
4015 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4016
4017 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4018}
4019
4020#ifdef CONFIG_KGDB_KDB
4021#include <linux/kdb.h>
4022/*
4023 * kdb_send_sig - Allows kdb to send signals without exposing
4024 * signal internals. This function checks if the required locks are
4025 * available before calling the main signal code, to avoid kdb
4026 * deadlocks.
4027 */
4028void kdb_send_sig(struct task_struct *t, int sig)
4029{
4030 static struct task_struct *kdb_prev_t;
4031 int new_t, ret;
4032 if (!spin_trylock(&t->sighand->siglock)) {
4033 kdb_printf("Can't do kill command now.\n"
4034 "The sigmask lock is held somewhere else in "
4035 "kernel, try again later\n");
4036 return;
4037 }
4038 new_t = kdb_prev_t != t;
4039 kdb_prev_t = t;
4040 if (t->state != TASK_RUNNING && new_t) {
4041 spin_unlock(&t->sighand->siglock);
4042 kdb_printf("Process is not RUNNING, sending a signal from "
4043 "kdb risks deadlock\n"
4044 "on the run queue locks. "
4045 "The signal has _not_ been sent.\n"
4046 "Reissue the kill command if you want to risk "
4047 "the deadlock.\n");
4048 return;
4049 }
4050 ret = send_signal(sig, SEND_SIG_PRIV, t, false);
4051 spin_unlock(&t->sighand->siglock);
4052 if (ret)
4053 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4054 sig, t->pid);
4055 else
4056 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4057}
4058#endif /* CONFIG_KGDB_KDB */