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1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/coredump.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/ptrace.h>
24#include <linux/signal.h>
25#include <linux/signalfd.h>
26#include <linux/ratelimit.h>
27#include <linux/tracehook.h>
28#include <linux/capability.h>
29#include <linux/freezer.h>
30#include <linux/pid_namespace.h>
31#include <linux/nsproxy.h>
32#include <linux/user_namespace.h>
33#include <linux/uprobes.h>
34#include <linux/compat.h>
35#include <linux/cn_proc.h>
36#include <linux/compiler.h>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <asm/uaccess.h>
43#include <asm/unistd.h>
44#include <asm/siginfo.h>
45#include <asm/cacheflush.h>
46#include "audit.h" /* audit_signal_info() */
47
48/*
49 * SLAB caches for signal bits.
50 */
51
52static struct kmem_cache *sigqueue_cachep;
53
54int print_fatal_signals __read_mostly;
55
56static void __user *sig_handler(struct task_struct *t, int sig)
57{
58 return t->sighand->action[sig - 1].sa.sa_handler;
59}
60
61static int sig_handler_ignored(void __user *handler, int sig)
62{
63 /* Is it explicitly or implicitly ignored? */
64 return handler == SIG_IGN ||
65 (handler == SIG_DFL && sig_kernel_ignore(sig));
66}
67
68static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69{
70 void __user *handler;
71
72 handler = sig_handler(t, sig);
73
74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 handler == SIG_DFL && !force)
76 return 1;
77
78 return sig_handler_ignored(handler, sig);
79}
80
81static int sig_ignored(struct task_struct *t, int sig, bool force)
82{
83 /*
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
86 * unblocked.
87 */
88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 return 0;
90
91 if (!sig_task_ignored(t, sig, force))
92 return 0;
93
94 /*
95 * Tracers may want to know about even ignored signals.
96 */
97 return !t->ptrace;
98}
99
100/*
101 * Re-calculate pending state from the set of locally pending
102 * signals, globally pending signals, and blocked signals.
103 */
104static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105{
106 unsigned long ready;
107 long i;
108
109 switch (_NSIG_WORDS) {
110 default:
111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 ready |= signal->sig[i] &~ blocked->sig[i];
113 break;
114
115 case 4: ready = signal->sig[3] &~ blocked->sig[3];
116 ready |= signal->sig[2] &~ blocked->sig[2];
117 ready |= signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
119 break;
120
121 case 2: ready = signal->sig[1] &~ blocked->sig[1];
122 ready |= signal->sig[0] &~ blocked->sig[0];
123 break;
124
125 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 }
127 return ready != 0;
128}
129
130#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131
132static int recalc_sigpending_tsk(struct task_struct *t)
133{
134 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 PENDING(&t->pending, &t->blocked) ||
136 PENDING(&t->signal->shared_pending, &t->blocked)) {
137 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 return 1;
139 }
140 /*
141 * We must never clear the flag in another thread, or in current
142 * when it's possible the current syscall is returning -ERESTART*.
143 * So we don't clear it here, and only callers who know they should do.
144 */
145 return 0;
146}
147
148/*
149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150 * This is superfluous when called on current, the wakeup is a harmless no-op.
151 */
152void recalc_sigpending_and_wake(struct task_struct *t)
153{
154 if (recalc_sigpending_tsk(t))
155 signal_wake_up(t, 0);
156}
157
158void recalc_sigpending(void)
159{
160 if (!recalc_sigpending_tsk(current) && !freezing(current))
161 clear_thread_flag(TIF_SIGPENDING);
162
163}
164
165/* Given the mask, find the first available signal that should be serviced. */
166
167#define SYNCHRONOUS_MASK \
168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170
171int next_signal(struct sigpending *pending, sigset_t *mask)
172{
173 unsigned long i, *s, *m, x;
174 int sig = 0;
175
176 s = pending->signal.sig;
177 m = mask->sig;
178
179 /*
180 * Handle the first word specially: it contains the
181 * synchronous signals that need to be dequeued first.
182 */
183 x = *s &~ *m;
184 if (x) {
185 if (x & SYNCHRONOUS_MASK)
186 x &= SYNCHRONOUS_MASK;
187 sig = ffz(~x) + 1;
188 return sig;
189 }
190
191 switch (_NSIG_WORDS) {
192 default:
193 for (i = 1; i < _NSIG_WORDS; ++i) {
194 x = *++s &~ *++m;
195 if (!x)
196 continue;
197 sig = ffz(~x) + i*_NSIG_BPW + 1;
198 break;
199 }
200 break;
201
202 case 2:
203 x = s[1] &~ m[1];
204 if (!x)
205 break;
206 sig = ffz(~x) + _NSIG_BPW + 1;
207 break;
208
209 case 1:
210 /* Nothing to do */
211 break;
212 }
213
214 return sig;
215}
216
217static inline void print_dropped_signal(int sig)
218{
219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220
221 if (!print_fatal_signals)
222 return;
223
224 if (!__ratelimit(&ratelimit_state))
225 return;
226
227 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 current->comm, current->pid, sig);
229}
230
231/**
232 * task_set_jobctl_pending - set jobctl pending bits
233 * @task: target task
234 * @mask: pending bits to set
235 *
236 * Clear @mask from @task->jobctl. @mask must be subset of
237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
239 * cleared. If @task is already being killed or exiting, this function
240 * becomes noop.
241 *
242 * CONTEXT:
243 * Must be called with @task->sighand->siglock held.
244 *
245 * RETURNS:
246 * %true if @mask is set, %false if made noop because @task was dying.
247 */
248bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
249{
250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253
254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 return false;
256
257 if (mask & JOBCTL_STOP_SIGMASK)
258 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259
260 task->jobctl |= mask;
261 return true;
262}
263
264/**
265 * task_clear_jobctl_trapping - clear jobctl trapping bit
266 * @task: target task
267 *
268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269 * Clear it and wake up the ptracer. Note that we don't need any further
270 * locking. @task->siglock guarantees that @task->parent points to the
271 * ptracer.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 */
276void task_clear_jobctl_trapping(struct task_struct *task)
277{
278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 task->jobctl &= ~JOBCTL_TRAPPING;
280 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
281 }
282}
283
284/**
285 * task_clear_jobctl_pending - clear jobctl pending bits
286 * @task: target task
287 * @mask: pending bits to clear
288 *
289 * Clear @mask from @task->jobctl. @mask must be subset of
290 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
291 * STOP bits are cleared together.
292 *
293 * If clearing of @mask leaves no stop or trap pending, this function calls
294 * task_clear_jobctl_trapping().
295 *
296 * CONTEXT:
297 * Must be called with @task->sighand->siglock held.
298 */
299void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
300{
301 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
302
303 if (mask & JOBCTL_STOP_PENDING)
304 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
305
306 task->jobctl &= ~mask;
307
308 if (!(task->jobctl & JOBCTL_PENDING_MASK))
309 task_clear_jobctl_trapping(task);
310}
311
312/**
313 * task_participate_group_stop - participate in a group stop
314 * @task: task participating in a group stop
315 *
316 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
317 * Group stop states are cleared and the group stop count is consumed if
318 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
319 * stop, the appropriate %SIGNAL_* flags are set.
320 *
321 * CONTEXT:
322 * Must be called with @task->sighand->siglock held.
323 *
324 * RETURNS:
325 * %true if group stop completion should be notified to the parent, %false
326 * otherwise.
327 */
328static bool task_participate_group_stop(struct task_struct *task)
329{
330 struct signal_struct *sig = task->signal;
331 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
332
333 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
334
335 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
336
337 if (!consume)
338 return false;
339
340 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
341 sig->group_stop_count--;
342
343 /*
344 * Tell the caller to notify completion iff we are entering into a
345 * fresh group stop. Read comment in do_signal_stop() for details.
346 */
347 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
348 sig->flags = SIGNAL_STOP_STOPPED;
349 return true;
350 }
351 return false;
352}
353
354/*
355 * allocate a new signal queue record
356 * - this may be called without locks if and only if t == current, otherwise an
357 * appropriate lock must be held to stop the target task from exiting
358 */
359static struct sigqueue *
360__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
361{
362 struct sigqueue *q = NULL;
363 struct user_struct *user;
364
365 /*
366 * Protect access to @t credentials. This can go away when all
367 * callers hold rcu read lock.
368 */
369 rcu_read_lock();
370 user = get_uid(__task_cred(t)->user);
371 atomic_inc(&user->sigpending);
372 rcu_read_unlock();
373
374 if (override_rlimit ||
375 atomic_read(&user->sigpending) <=
376 task_rlimit(t, RLIMIT_SIGPENDING)) {
377 q = kmem_cache_alloc(sigqueue_cachep, flags);
378 } else {
379 print_dropped_signal(sig);
380 }
381
382 if (unlikely(q == NULL)) {
383 atomic_dec(&user->sigpending);
384 free_uid(user);
385 } else {
386 INIT_LIST_HEAD(&q->list);
387 q->flags = 0;
388 q->user = user;
389 }
390
391 return q;
392}
393
394static void __sigqueue_free(struct sigqueue *q)
395{
396 if (q->flags & SIGQUEUE_PREALLOC)
397 return;
398 atomic_dec(&q->user->sigpending);
399 free_uid(q->user);
400 kmem_cache_free(sigqueue_cachep, q);
401}
402
403void flush_sigqueue(struct sigpending *queue)
404{
405 struct sigqueue *q;
406
407 sigemptyset(&queue->signal);
408 while (!list_empty(&queue->list)) {
409 q = list_entry(queue->list.next, struct sigqueue , list);
410 list_del_init(&q->list);
411 __sigqueue_free(q);
412 }
413}
414
415/*
416 * Flush all pending signals for a task.
417 */
418void __flush_signals(struct task_struct *t)
419{
420 clear_tsk_thread_flag(t, TIF_SIGPENDING);
421 flush_sigqueue(&t->pending);
422 flush_sigqueue(&t->signal->shared_pending);
423}
424
425void flush_signals(struct task_struct *t)
426{
427 unsigned long flags;
428
429 spin_lock_irqsave(&t->sighand->siglock, flags);
430 __flush_signals(t);
431 spin_unlock_irqrestore(&t->sighand->siglock, flags);
432}
433
434static void __flush_itimer_signals(struct sigpending *pending)
435{
436 sigset_t signal, retain;
437 struct sigqueue *q, *n;
438
439 signal = pending->signal;
440 sigemptyset(&retain);
441
442 list_for_each_entry_safe(q, n, &pending->list, list) {
443 int sig = q->info.si_signo;
444
445 if (likely(q->info.si_code != SI_TIMER)) {
446 sigaddset(&retain, sig);
447 } else {
448 sigdelset(&signal, sig);
449 list_del_init(&q->list);
450 __sigqueue_free(q);
451 }
452 }
453
454 sigorsets(&pending->signal, &signal, &retain);
455}
456
457void flush_itimer_signals(void)
458{
459 struct task_struct *tsk = current;
460 unsigned long flags;
461
462 spin_lock_irqsave(&tsk->sighand->siglock, flags);
463 __flush_itimer_signals(&tsk->pending);
464 __flush_itimer_signals(&tsk->signal->shared_pending);
465 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
466}
467
468void ignore_signals(struct task_struct *t)
469{
470 int i;
471
472 for (i = 0; i < _NSIG; ++i)
473 t->sighand->action[i].sa.sa_handler = SIG_IGN;
474
475 flush_signals(t);
476}
477
478/*
479 * Flush all handlers for a task.
480 */
481
482void
483flush_signal_handlers(struct task_struct *t, int force_default)
484{
485 int i;
486 struct k_sigaction *ka = &t->sighand->action[0];
487 for (i = _NSIG ; i != 0 ; i--) {
488 if (force_default || ka->sa.sa_handler != SIG_IGN)
489 ka->sa.sa_handler = SIG_DFL;
490 ka->sa.sa_flags = 0;
491#ifdef __ARCH_HAS_SA_RESTORER
492 ka->sa.sa_restorer = NULL;
493#endif
494 sigemptyset(&ka->sa.sa_mask);
495 ka++;
496 }
497}
498
499int unhandled_signal(struct task_struct *tsk, int sig)
500{
501 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
502 if (is_global_init(tsk))
503 return 1;
504 if (handler != SIG_IGN && handler != SIG_DFL)
505 return 0;
506 /* if ptraced, let the tracer determine */
507 return !tsk->ptrace;
508}
509
510/*
511 * Notify the system that a driver wants to block all signals for this
512 * process, and wants to be notified if any signals at all were to be
513 * sent/acted upon. If the notifier routine returns non-zero, then the
514 * signal will be acted upon after all. If the notifier routine returns 0,
515 * then then signal will be blocked. Only one block per process is
516 * allowed. priv is a pointer to private data that the notifier routine
517 * can use to determine if the signal should be blocked or not.
518 */
519void
520block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
521{
522 unsigned long flags;
523
524 spin_lock_irqsave(¤t->sighand->siglock, flags);
525 current->notifier_mask = mask;
526 current->notifier_data = priv;
527 current->notifier = notifier;
528 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
529}
530
531/* Notify the system that blocking has ended. */
532
533void
534unblock_all_signals(void)
535{
536 unsigned long flags;
537
538 spin_lock_irqsave(¤t->sighand->siglock, flags);
539 current->notifier = NULL;
540 current->notifier_data = NULL;
541 recalc_sigpending();
542 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
543}
544
545static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
546{
547 struct sigqueue *q, *first = NULL;
548
549 /*
550 * Collect the siginfo appropriate to this signal. Check if
551 * there is another siginfo for the same signal.
552 */
553 list_for_each_entry(q, &list->list, list) {
554 if (q->info.si_signo == sig) {
555 if (first)
556 goto still_pending;
557 first = q;
558 }
559 }
560
561 sigdelset(&list->signal, sig);
562
563 if (first) {
564still_pending:
565 list_del_init(&first->list);
566 copy_siginfo(info, &first->info);
567 __sigqueue_free(first);
568 } else {
569 /*
570 * Ok, it wasn't in the queue. This must be
571 * a fast-pathed signal or we must have been
572 * out of queue space. So zero out the info.
573 */
574 info->si_signo = sig;
575 info->si_errno = 0;
576 info->si_code = SI_USER;
577 info->si_pid = 0;
578 info->si_uid = 0;
579 }
580}
581
582static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
583 siginfo_t *info)
584{
585 int sig = next_signal(pending, mask);
586
587 if (sig) {
588 if (current->notifier) {
589 if (sigismember(current->notifier_mask, sig)) {
590 if (!(current->notifier)(current->notifier_data)) {
591 clear_thread_flag(TIF_SIGPENDING);
592 return 0;
593 }
594 }
595 }
596
597 collect_signal(sig, pending, info);
598 }
599
600 return sig;
601}
602
603/*
604 * Dequeue a signal and return the element to the caller, which is
605 * expected to free it.
606 *
607 * All callers have to hold the siglock.
608 */
609int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
610{
611 int signr;
612
613 /* We only dequeue private signals from ourselves, we don't let
614 * signalfd steal them
615 */
616 signr = __dequeue_signal(&tsk->pending, mask, info);
617 if (!signr) {
618 signr = __dequeue_signal(&tsk->signal->shared_pending,
619 mask, info);
620 /*
621 * itimer signal ?
622 *
623 * itimers are process shared and we restart periodic
624 * itimers in the signal delivery path to prevent DoS
625 * attacks in the high resolution timer case. This is
626 * compliant with the old way of self-restarting
627 * itimers, as the SIGALRM is a legacy signal and only
628 * queued once. Changing the restart behaviour to
629 * restart the timer in the signal dequeue path is
630 * reducing the timer noise on heavy loaded !highres
631 * systems too.
632 */
633 if (unlikely(signr == SIGALRM)) {
634 struct hrtimer *tmr = &tsk->signal->real_timer;
635
636 if (!hrtimer_is_queued(tmr) &&
637 tsk->signal->it_real_incr.tv64 != 0) {
638 hrtimer_forward(tmr, tmr->base->get_time(),
639 tsk->signal->it_real_incr);
640 hrtimer_restart(tmr);
641 }
642 }
643 }
644
645 recalc_sigpending();
646 if (!signr)
647 return 0;
648
649 if (unlikely(sig_kernel_stop(signr))) {
650 /*
651 * Set a marker that we have dequeued a stop signal. Our
652 * caller might release the siglock and then the pending
653 * stop signal it is about to process is no longer in the
654 * pending bitmasks, but must still be cleared by a SIGCONT
655 * (and overruled by a SIGKILL). So those cases clear this
656 * shared flag after we've set it. Note that this flag may
657 * remain set after the signal we return is ignored or
658 * handled. That doesn't matter because its only purpose
659 * is to alert stop-signal processing code when another
660 * processor has come along and cleared the flag.
661 */
662 current->jobctl |= JOBCTL_STOP_DEQUEUED;
663 }
664 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
665 /*
666 * Release the siglock to ensure proper locking order
667 * of timer locks outside of siglocks. Note, we leave
668 * irqs disabled here, since the posix-timers code is
669 * about to disable them again anyway.
670 */
671 spin_unlock(&tsk->sighand->siglock);
672 do_schedule_next_timer(info);
673 spin_lock(&tsk->sighand->siglock);
674 }
675 return signr;
676}
677
678/*
679 * Tell a process that it has a new active signal..
680 *
681 * NOTE! we rely on the previous spin_lock to
682 * lock interrupts for us! We can only be called with
683 * "siglock" held, and the local interrupt must
684 * have been disabled when that got acquired!
685 *
686 * No need to set need_resched since signal event passing
687 * goes through ->blocked
688 */
689void signal_wake_up_state(struct task_struct *t, unsigned int state)
690{
691 set_tsk_thread_flag(t, TIF_SIGPENDING);
692 /*
693 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
694 * case. We don't check t->state here because there is a race with it
695 * executing another processor and just now entering stopped state.
696 * By using wake_up_state, we ensure the process will wake up and
697 * handle its death signal.
698 */
699 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
700 kick_process(t);
701}
702
703/*
704 * Remove signals in mask from the pending set and queue.
705 * Returns 1 if any signals were found.
706 *
707 * All callers must be holding the siglock.
708 *
709 * This version takes a sigset mask and looks at all signals,
710 * not just those in the first mask word.
711 */
712static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
713{
714 struct sigqueue *q, *n;
715 sigset_t m;
716
717 sigandsets(&m, mask, &s->signal);
718 if (sigisemptyset(&m))
719 return 0;
720
721 sigandnsets(&s->signal, &s->signal, mask);
722 list_for_each_entry_safe(q, n, &s->list, list) {
723 if (sigismember(mask, q->info.si_signo)) {
724 list_del_init(&q->list);
725 __sigqueue_free(q);
726 }
727 }
728 return 1;
729}
730/*
731 * Remove signals in mask from the pending set and queue.
732 * Returns 1 if any signals were found.
733 *
734 * All callers must be holding the siglock.
735 */
736static int rm_from_queue(unsigned long mask, struct sigpending *s)
737{
738 struct sigqueue *q, *n;
739
740 if (!sigtestsetmask(&s->signal, mask))
741 return 0;
742
743 sigdelsetmask(&s->signal, mask);
744 list_for_each_entry_safe(q, n, &s->list, list) {
745 if (q->info.si_signo < SIGRTMIN &&
746 (mask & sigmask(q->info.si_signo))) {
747 list_del_init(&q->list);
748 __sigqueue_free(q);
749 }
750 }
751 return 1;
752}
753
754static inline int is_si_special(const struct siginfo *info)
755{
756 return info <= SEND_SIG_FORCED;
757}
758
759static inline bool si_fromuser(const struct siginfo *info)
760{
761 return info == SEND_SIG_NOINFO ||
762 (!is_si_special(info) && SI_FROMUSER(info));
763}
764
765/*
766 * called with RCU read lock from check_kill_permission()
767 */
768static int kill_ok_by_cred(struct task_struct *t)
769{
770 const struct cred *cred = current_cred();
771 const struct cred *tcred = __task_cred(t);
772
773 if (uid_eq(cred->euid, tcred->suid) ||
774 uid_eq(cred->euid, tcred->uid) ||
775 uid_eq(cred->uid, tcred->suid) ||
776 uid_eq(cred->uid, tcred->uid))
777 return 1;
778
779 if (ns_capable(tcred->user_ns, CAP_KILL))
780 return 1;
781
782 return 0;
783}
784
785/*
786 * Bad permissions for sending the signal
787 * - the caller must hold the RCU read lock
788 */
789static int check_kill_permission(int sig, struct siginfo *info,
790 struct task_struct *t)
791{
792 struct pid *sid;
793 int error;
794
795 if (!valid_signal(sig))
796 return -EINVAL;
797
798 if (!si_fromuser(info))
799 return 0;
800
801 error = audit_signal_info(sig, t); /* Let audit system see the signal */
802 if (error)
803 return error;
804
805 if (!same_thread_group(current, t) &&
806 !kill_ok_by_cred(t)) {
807 switch (sig) {
808 case SIGCONT:
809 sid = task_session(t);
810 /*
811 * We don't return the error if sid == NULL. The
812 * task was unhashed, the caller must notice this.
813 */
814 if (!sid || sid == task_session(current))
815 break;
816 default:
817 return -EPERM;
818 }
819 }
820
821 return security_task_kill(t, info, sig, 0);
822}
823
824/**
825 * ptrace_trap_notify - schedule trap to notify ptracer
826 * @t: tracee wanting to notify tracer
827 *
828 * This function schedules sticky ptrace trap which is cleared on the next
829 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
830 * ptracer.
831 *
832 * If @t is running, STOP trap will be taken. If trapped for STOP and
833 * ptracer is listening for events, tracee is woken up so that it can
834 * re-trap for the new event. If trapped otherwise, STOP trap will be
835 * eventually taken without returning to userland after the existing traps
836 * are finished by PTRACE_CONT.
837 *
838 * CONTEXT:
839 * Must be called with @task->sighand->siglock held.
840 */
841static void ptrace_trap_notify(struct task_struct *t)
842{
843 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
844 assert_spin_locked(&t->sighand->siglock);
845
846 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
847 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
848}
849
850/*
851 * Handle magic process-wide effects of stop/continue signals. Unlike
852 * the signal actions, these happen immediately at signal-generation
853 * time regardless of blocking, ignoring, or handling. This does the
854 * actual continuing for SIGCONT, but not the actual stopping for stop
855 * signals. The process stop is done as a signal action for SIG_DFL.
856 *
857 * Returns true if the signal should be actually delivered, otherwise
858 * it should be dropped.
859 */
860static bool prepare_signal(int sig, struct task_struct *p, bool force)
861{
862 struct signal_struct *signal = p->signal;
863 struct task_struct *t;
864
865 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
866 if (signal->flags & SIGNAL_GROUP_COREDUMP)
867 return sig == SIGKILL;
868 /*
869 * The process is in the middle of dying, nothing to do.
870 */
871 } else if (sig_kernel_stop(sig)) {
872 /*
873 * This is a stop signal. Remove SIGCONT from all queues.
874 */
875 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
876 t = p;
877 do {
878 rm_from_queue(sigmask(SIGCONT), &t->pending);
879 } while_each_thread(p, t);
880 } else if (sig == SIGCONT) {
881 unsigned int why;
882 /*
883 * Remove all stop signals from all queues, wake all threads.
884 */
885 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
886 t = p;
887 do {
888 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
889 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
890 if (likely(!(t->ptrace & PT_SEIZED)))
891 wake_up_state(t, __TASK_STOPPED);
892 else
893 ptrace_trap_notify(t);
894 } while_each_thread(p, t);
895
896 /*
897 * Notify the parent with CLD_CONTINUED if we were stopped.
898 *
899 * If we were in the middle of a group stop, we pretend it
900 * was already finished, and then continued. Since SIGCHLD
901 * doesn't queue we report only CLD_STOPPED, as if the next
902 * CLD_CONTINUED was dropped.
903 */
904 why = 0;
905 if (signal->flags & SIGNAL_STOP_STOPPED)
906 why |= SIGNAL_CLD_CONTINUED;
907 else if (signal->group_stop_count)
908 why |= SIGNAL_CLD_STOPPED;
909
910 if (why) {
911 /*
912 * The first thread which returns from do_signal_stop()
913 * will take ->siglock, notice SIGNAL_CLD_MASK, and
914 * notify its parent. See get_signal_to_deliver().
915 */
916 signal->flags = why | SIGNAL_STOP_CONTINUED;
917 signal->group_stop_count = 0;
918 signal->group_exit_code = 0;
919 }
920 }
921
922 return !sig_ignored(p, sig, force);
923}
924
925/*
926 * Test if P wants to take SIG. After we've checked all threads with this,
927 * it's equivalent to finding no threads not blocking SIG. Any threads not
928 * blocking SIG were ruled out because they are not running and already
929 * have pending signals. Such threads will dequeue from the shared queue
930 * as soon as they're available, so putting the signal on the shared queue
931 * will be equivalent to sending it to one such thread.
932 */
933static inline int wants_signal(int sig, struct task_struct *p)
934{
935 if (sigismember(&p->blocked, sig))
936 return 0;
937 if (p->flags & PF_EXITING)
938 return 0;
939 if (sig == SIGKILL)
940 return 1;
941 if (task_is_stopped_or_traced(p))
942 return 0;
943 return task_curr(p) || !signal_pending(p);
944}
945
946static void complete_signal(int sig, struct task_struct *p, int group)
947{
948 struct signal_struct *signal = p->signal;
949 struct task_struct *t;
950
951 /*
952 * Now find a thread we can wake up to take the signal off the queue.
953 *
954 * If the main thread wants the signal, it gets first crack.
955 * Probably the least surprising to the average bear.
956 */
957 if (wants_signal(sig, p))
958 t = p;
959 else if (!group || thread_group_empty(p))
960 /*
961 * There is just one thread and it does not need to be woken.
962 * It will dequeue unblocked signals before it runs again.
963 */
964 return;
965 else {
966 /*
967 * Otherwise try to find a suitable thread.
968 */
969 t = signal->curr_target;
970 while (!wants_signal(sig, t)) {
971 t = next_thread(t);
972 if (t == signal->curr_target)
973 /*
974 * No thread needs to be woken.
975 * Any eligible threads will see
976 * the signal in the queue soon.
977 */
978 return;
979 }
980 signal->curr_target = t;
981 }
982
983 /*
984 * Found a killable thread. If the signal will be fatal,
985 * then start taking the whole group down immediately.
986 */
987 if (sig_fatal(p, sig) &&
988 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
989 !sigismember(&t->real_blocked, sig) &&
990 (sig == SIGKILL || !t->ptrace)) {
991 /*
992 * This signal will be fatal to the whole group.
993 */
994 if (!sig_kernel_coredump(sig)) {
995 /*
996 * Start a group exit and wake everybody up.
997 * This way we don't have other threads
998 * running and doing things after a slower
999 * thread has the fatal signal pending.
1000 */
1001 signal->flags = SIGNAL_GROUP_EXIT;
1002 signal->group_exit_code = sig;
1003 signal->group_stop_count = 0;
1004 t = p;
1005 do {
1006 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1007 sigaddset(&t->pending.signal, SIGKILL);
1008 signal_wake_up(t, 1);
1009 } while_each_thread(p, t);
1010 return;
1011 }
1012 }
1013
1014 /*
1015 * The signal is already in the shared-pending queue.
1016 * Tell the chosen thread to wake up and dequeue it.
1017 */
1018 signal_wake_up(t, sig == SIGKILL);
1019 return;
1020}
1021
1022static inline int legacy_queue(struct sigpending *signals, int sig)
1023{
1024 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1025}
1026
1027#ifdef CONFIG_USER_NS
1028static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1029{
1030 if (current_user_ns() == task_cred_xxx(t, user_ns))
1031 return;
1032
1033 if (SI_FROMKERNEL(info))
1034 return;
1035
1036 rcu_read_lock();
1037 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1038 make_kuid(current_user_ns(), info->si_uid));
1039 rcu_read_unlock();
1040}
1041#else
1042static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1043{
1044 return;
1045}
1046#endif
1047
1048static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1049 int group, int from_ancestor_ns)
1050{
1051 struct sigpending *pending;
1052 struct sigqueue *q;
1053 int override_rlimit;
1054 int ret = 0, result;
1055
1056 assert_spin_locked(&t->sighand->siglock);
1057
1058 result = TRACE_SIGNAL_IGNORED;
1059 if (!prepare_signal(sig, t,
1060 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1061 goto ret;
1062
1063 pending = group ? &t->signal->shared_pending : &t->pending;
1064 /*
1065 * Short-circuit ignored signals and support queuing
1066 * exactly one non-rt signal, so that we can get more
1067 * detailed information about the cause of the signal.
1068 */
1069 result = TRACE_SIGNAL_ALREADY_PENDING;
1070 if (legacy_queue(pending, sig))
1071 goto ret;
1072
1073 result = TRACE_SIGNAL_DELIVERED;
1074 /*
1075 * fast-pathed signals for kernel-internal things like SIGSTOP
1076 * or SIGKILL.
1077 */
1078 if (info == SEND_SIG_FORCED)
1079 goto out_set;
1080
1081 /*
1082 * Real-time signals must be queued if sent by sigqueue, or
1083 * some other real-time mechanism. It is implementation
1084 * defined whether kill() does so. We attempt to do so, on
1085 * the principle of least surprise, but since kill is not
1086 * allowed to fail with EAGAIN when low on memory we just
1087 * make sure at least one signal gets delivered and don't
1088 * pass on the info struct.
1089 */
1090 if (sig < SIGRTMIN)
1091 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1092 else
1093 override_rlimit = 0;
1094
1095 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1096 override_rlimit);
1097 if (q) {
1098 list_add_tail(&q->list, &pending->list);
1099 switch ((unsigned long) info) {
1100 case (unsigned long) SEND_SIG_NOINFO:
1101 q->info.si_signo = sig;
1102 q->info.si_errno = 0;
1103 q->info.si_code = SI_USER;
1104 q->info.si_pid = task_tgid_nr_ns(current,
1105 task_active_pid_ns(t));
1106 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1107 break;
1108 case (unsigned long) SEND_SIG_PRIV:
1109 q->info.si_signo = sig;
1110 q->info.si_errno = 0;
1111 q->info.si_code = SI_KERNEL;
1112 q->info.si_pid = 0;
1113 q->info.si_uid = 0;
1114 break;
1115 default:
1116 copy_siginfo(&q->info, info);
1117 if (from_ancestor_ns)
1118 q->info.si_pid = 0;
1119 break;
1120 }
1121
1122 userns_fixup_signal_uid(&q->info, t);
1123
1124 } else if (!is_si_special(info)) {
1125 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1126 /*
1127 * Queue overflow, abort. We may abort if the
1128 * signal was rt and sent by user using something
1129 * other than kill().
1130 */
1131 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1132 ret = -EAGAIN;
1133 goto ret;
1134 } else {
1135 /*
1136 * This is a silent loss of information. We still
1137 * send the signal, but the *info bits are lost.
1138 */
1139 result = TRACE_SIGNAL_LOSE_INFO;
1140 }
1141 }
1142
1143out_set:
1144 signalfd_notify(t, sig);
1145 sigaddset(&pending->signal, sig);
1146 complete_signal(sig, t, group);
1147ret:
1148 trace_signal_generate(sig, info, t, group, result);
1149 return ret;
1150}
1151
1152static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1153 int group)
1154{
1155 int from_ancestor_ns = 0;
1156
1157#ifdef CONFIG_PID_NS
1158 from_ancestor_ns = si_fromuser(info) &&
1159 !task_pid_nr_ns(current, task_active_pid_ns(t));
1160#endif
1161
1162 return __send_signal(sig, info, t, group, from_ancestor_ns);
1163}
1164
1165static void print_fatal_signal(int signr)
1166{
1167 struct pt_regs *regs = signal_pt_regs();
1168 printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1169
1170#if defined(__i386__) && !defined(__arch_um__)
1171 printk(KERN_INFO "code at %08lx: ", regs->ip);
1172 {
1173 int i;
1174 for (i = 0; i < 16; i++) {
1175 unsigned char insn;
1176
1177 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1178 break;
1179 printk(KERN_CONT "%02x ", insn);
1180 }
1181 }
1182 printk(KERN_CONT "\n");
1183#endif
1184 preempt_disable();
1185 show_regs(regs);
1186 preempt_enable();
1187}
1188
1189static int __init setup_print_fatal_signals(char *str)
1190{
1191 get_option (&str, &print_fatal_signals);
1192
1193 return 1;
1194}
1195
1196__setup("print-fatal-signals=", setup_print_fatal_signals);
1197
1198int
1199__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1200{
1201 return send_signal(sig, info, p, 1);
1202}
1203
1204static int
1205specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1206{
1207 return send_signal(sig, info, t, 0);
1208}
1209
1210int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1211 bool group)
1212{
1213 unsigned long flags;
1214 int ret = -ESRCH;
1215
1216 if (lock_task_sighand(p, &flags)) {
1217 ret = send_signal(sig, info, p, group);
1218 unlock_task_sighand(p, &flags);
1219 }
1220
1221 return ret;
1222}
1223
1224/*
1225 * Force a signal that the process can't ignore: if necessary
1226 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1227 *
1228 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1229 * since we do not want to have a signal handler that was blocked
1230 * be invoked when user space had explicitly blocked it.
1231 *
1232 * We don't want to have recursive SIGSEGV's etc, for example,
1233 * that is why we also clear SIGNAL_UNKILLABLE.
1234 */
1235int
1236force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1237{
1238 unsigned long int flags;
1239 int ret, blocked, ignored;
1240 struct k_sigaction *action;
1241
1242 spin_lock_irqsave(&t->sighand->siglock, flags);
1243 action = &t->sighand->action[sig-1];
1244 ignored = action->sa.sa_handler == SIG_IGN;
1245 blocked = sigismember(&t->blocked, sig);
1246 if (blocked || ignored) {
1247 action->sa.sa_handler = SIG_DFL;
1248 if (blocked) {
1249 sigdelset(&t->blocked, sig);
1250 recalc_sigpending_and_wake(t);
1251 }
1252 }
1253 if (action->sa.sa_handler == SIG_DFL)
1254 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1255 ret = specific_send_sig_info(sig, info, t);
1256 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1257
1258 return ret;
1259}
1260
1261/*
1262 * Nuke all other threads in the group.
1263 */
1264int zap_other_threads(struct task_struct *p)
1265{
1266 struct task_struct *t = p;
1267 int count = 0;
1268
1269 p->signal->group_stop_count = 0;
1270
1271 while_each_thread(p, t) {
1272 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1273 count++;
1274
1275 /* Don't bother with already dead threads */
1276 if (t->exit_state)
1277 continue;
1278 sigaddset(&t->pending.signal, SIGKILL);
1279 signal_wake_up(t, 1);
1280 }
1281
1282 return count;
1283}
1284
1285struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1286 unsigned long *flags)
1287{
1288 struct sighand_struct *sighand;
1289
1290 for (;;) {
1291 local_irq_save(*flags);
1292 rcu_read_lock();
1293 sighand = rcu_dereference(tsk->sighand);
1294 if (unlikely(sighand == NULL)) {
1295 rcu_read_unlock();
1296 local_irq_restore(*flags);
1297 break;
1298 }
1299
1300 spin_lock(&sighand->siglock);
1301 if (likely(sighand == tsk->sighand)) {
1302 rcu_read_unlock();
1303 break;
1304 }
1305 spin_unlock(&sighand->siglock);
1306 rcu_read_unlock();
1307 local_irq_restore(*flags);
1308 }
1309
1310 return sighand;
1311}
1312
1313/*
1314 * send signal info to all the members of a group
1315 */
1316int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1317{
1318 int ret;
1319
1320 rcu_read_lock();
1321 ret = check_kill_permission(sig, info, p);
1322 rcu_read_unlock();
1323
1324 if (!ret && sig)
1325 ret = do_send_sig_info(sig, info, p, true);
1326
1327 return ret;
1328}
1329
1330/*
1331 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1332 * control characters do (^C, ^Z etc)
1333 * - the caller must hold at least a readlock on tasklist_lock
1334 */
1335int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1336{
1337 struct task_struct *p = NULL;
1338 int retval, success;
1339
1340 success = 0;
1341 retval = -ESRCH;
1342 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1343 int err = group_send_sig_info(sig, info, p);
1344 success |= !err;
1345 retval = err;
1346 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1347 return success ? 0 : retval;
1348}
1349
1350int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1351{
1352 int error = -ESRCH;
1353 struct task_struct *p;
1354
1355 rcu_read_lock();
1356retry:
1357 p = pid_task(pid, PIDTYPE_PID);
1358 if (p) {
1359 error = group_send_sig_info(sig, info, p);
1360 if (unlikely(error == -ESRCH))
1361 /*
1362 * The task was unhashed in between, try again.
1363 * If it is dead, pid_task() will return NULL,
1364 * if we race with de_thread() it will find the
1365 * new leader.
1366 */
1367 goto retry;
1368 }
1369 rcu_read_unlock();
1370
1371 return error;
1372}
1373
1374int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1375{
1376 int error;
1377 rcu_read_lock();
1378 error = kill_pid_info(sig, info, find_vpid(pid));
1379 rcu_read_unlock();
1380 return error;
1381}
1382
1383static int kill_as_cred_perm(const struct cred *cred,
1384 struct task_struct *target)
1385{
1386 const struct cred *pcred = __task_cred(target);
1387 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1388 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1389 return 0;
1390 return 1;
1391}
1392
1393/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1394int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1395 const struct cred *cred, u32 secid)
1396{
1397 int ret = -EINVAL;
1398 struct task_struct *p;
1399 unsigned long flags;
1400
1401 if (!valid_signal(sig))
1402 return ret;
1403
1404 rcu_read_lock();
1405 p = pid_task(pid, PIDTYPE_PID);
1406 if (!p) {
1407 ret = -ESRCH;
1408 goto out_unlock;
1409 }
1410 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1411 ret = -EPERM;
1412 goto out_unlock;
1413 }
1414 ret = security_task_kill(p, info, sig, secid);
1415 if (ret)
1416 goto out_unlock;
1417
1418 if (sig) {
1419 if (lock_task_sighand(p, &flags)) {
1420 ret = __send_signal(sig, info, p, 1, 0);
1421 unlock_task_sighand(p, &flags);
1422 } else
1423 ret = -ESRCH;
1424 }
1425out_unlock:
1426 rcu_read_unlock();
1427 return ret;
1428}
1429EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1430
1431/*
1432 * kill_something_info() interprets pid in interesting ways just like kill(2).
1433 *
1434 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1435 * is probably wrong. Should make it like BSD or SYSV.
1436 */
1437
1438static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1439{
1440 int ret;
1441
1442 if (pid > 0) {
1443 rcu_read_lock();
1444 ret = kill_pid_info(sig, info, find_vpid(pid));
1445 rcu_read_unlock();
1446 return ret;
1447 }
1448
1449 read_lock(&tasklist_lock);
1450 if (pid != -1) {
1451 ret = __kill_pgrp_info(sig, info,
1452 pid ? find_vpid(-pid) : task_pgrp(current));
1453 } else {
1454 int retval = 0, count = 0;
1455 struct task_struct * p;
1456
1457 for_each_process(p) {
1458 if (task_pid_vnr(p) > 1 &&
1459 !same_thread_group(p, current)) {
1460 int err = group_send_sig_info(sig, info, p);
1461 ++count;
1462 if (err != -EPERM)
1463 retval = err;
1464 }
1465 }
1466 ret = count ? retval : -ESRCH;
1467 }
1468 read_unlock(&tasklist_lock);
1469
1470 return ret;
1471}
1472
1473/*
1474 * These are for backward compatibility with the rest of the kernel source.
1475 */
1476
1477int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1478{
1479 /*
1480 * Make sure legacy kernel users don't send in bad values
1481 * (normal paths check this in check_kill_permission).
1482 */
1483 if (!valid_signal(sig))
1484 return -EINVAL;
1485
1486 return do_send_sig_info(sig, info, p, false);
1487}
1488
1489#define __si_special(priv) \
1490 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1491
1492int
1493send_sig(int sig, struct task_struct *p, int priv)
1494{
1495 return send_sig_info(sig, __si_special(priv), p);
1496}
1497
1498void
1499force_sig(int sig, struct task_struct *p)
1500{
1501 force_sig_info(sig, SEND_SIG_PRIV, p);
1502}
1503
1504/*
1505 * When things go south during signal handling, we
1506 * will force a SIGSEGV. And if the signal that caused
1507 * the problem was already a SIGSEGV, we'll want to
1508 * make sure we don't even try to deliver the signal..
1509 */
1510int
1511force_sigsegv(int sig, struct task_struct *p)
1512{
1513 if (sig == SIGSEGV) {
1514 unsigned long flags;
1515 spin_lock_irqsave(&p->sighand->siglock, flags);
1516 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1517 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1518 }
1519 force_sig(SIGSEGV, p);
1520 return 0;
1521}
1522
1523int kill_pgrp(struct pid *pid, int sig, int priv)
1524{
1525 int ret;
1526
1527 read_lock(&tasklist_lock);
1528 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1529 read_unlock(&tasklist_lock);
1530
1531 return ret;
1532}
1533EXPORT_SYMBOL(kill_pgrp);
1534
1535int kill_pid(struct pid *pid, int sig, int priv)
1536{
1537 return kill_pid_info(sig, __si_special(priv), pid);
1538}
1539EXPORT_SYMBOL(kill_pid);
1540
1541/*
1542 * These functions support sending signals using preallocated sigqueue
1543 * structures. This is needed "because realtime applications cannot
1544 * afford to lose notifications of asynchronous events, like timer
1545 * expirations or I/O completions". In the case of POSIX Timers
1546 * we allocate the sigqueue structure from the timer_create. If this
1547 * allocation fails we are able to report the failure to the application
1548 * with an EAGAIN error.
1549 */
1550struct sigqueue *sigqueue_alloc(void)
1551{
1552 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1553
1554 if (q)
1555 q->flags |= SIGQUEUE_PREALLOC;
1556
1557 return q;
1558}
1559
1560void sigqueue_free(struct sigqueue *q)
1561{
1562 unsigned long flags;
1563 spinlock_t *lock = ¤t->sighand->siglock;
1564
1565 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1566 /*
1567 * We must hold ->siglock while testing q->list
1568 * to serialize with collect_signal() or with
1569 * __exit_signal()->flush_sigqueue().
1570 */
1571 spin_lock_irqsave(lock, flags);
1572 q->flags &= ~SIGQUEUE_PREALLOC;
1573 /*
1574 * If it is queued it will be freed when dequeued,
1575 * like the "regular" sigqueue.
1576 */
1577 if (!list_empty(&q->list))
1578 q = NULL;
1579 spin_unlock_irqrestore(lock, flags);
1580
1581 if (q)
1582 __sigqueue_free(q);
1583}
1584
1585int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1586{
1587 int sig = q->info.si_signo;
1588 struct sigpending *pending;
1589 unsigned long flags;
1590 int ret, result;
1591
1592 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1593
1594 ret = -1;
1595 if (!likely(lock_task_sighand(t, &flags)))
1596 goto ret;
1597
1598 ret = 1; /* the signal is ignored */
1599 result = TRACE_SIGNAL_IGNORED;
1600 if (!prepare_signal(sig, t, false))
1601 goto out;
1602
1603 ret = 0;
1604 if (unlikely(!list_empty(&q->list))) {
1605 /*
1606 * If an SI_TIMER entry is already queue just increment
1607 * the overrun count.
1608 */
1609 BUG_ON(q->info.si_code != SI_TIMER);
1610 q->info.si_overrun++;
1611 result = TRACE_SIGNAL_ALREADY_PENDING;
1612 goto out;
1613 }
1614 q->info.si_overrun = 0;
1615
1616 signalfd_notify(t, sig);
1617 pending = group ? &t->signal->shared_pending : &t->pending;
1618 list_add_tail(&q->list, &pending->list);
1619 sigaddset(&pending->signal, sig);
1620 complete_signal(sig, t, group);
1621 result = TRACE_SIGNAL_DELIVERED;
1622out:
1623 trace_signal_generate(sig, &q->info, t, group, result);
1624 unlock_task_sighand(t, &flags);
1625ret:
1626 return ret;
1627}
1628
1629/*
1630 * Let a parent know about the death of a child.
1631 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1632 *
1633 * Returns true if our parent ignored us and so we've switched to
1634 * self-reaping.
1635 */
1636bool do_notify_parent(struct task_struct *tsk, int sig)
1637{
1638 struct siginfo info;
1639 unsigned long flags;
1640 struct sighand_struct *psig;
1641 bool autoreap = false;
1642 cputime_t utime, stime;
1643
1644 BUG_ON(sig == -1);
1645
1646 /* do_notify_parent_cldstop should have been called instead. */
1647 BUG_ON(task_is_stopped_or_traced(tsk));
1648
1649 BUG_ON(!tsk->ptrace &&
1650 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1651
1652 if (sig != SIGCHLD) {
1653 /*
1654 * This is only possible if parent == real_parent.
1655 * Check if it has changed security domain.
1656 */
1657 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1658 sig = SIGCHLD;
1659 }
1660
1661 info.si_signo = sig;
1662 info.si_errno = 0;
1663 /*
1664 * We are under tasklist_lock here so our parent is tied to
1665 * us and cannot change.
1666 *
1667 * task_active_pid_ns will always return the same pid namespace
1668 * until a task passes through release_task.
1669 *
1670 * write_lock() currently calls preempt_disable() which is the
1671 * same as rcu_read_lock(), but according to Oleg, this is not
1672 * correct to rely on this
1673 */
1674 rcu_read_lock();
1675 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1676 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1677 task_uid(tsk));
1678 rcu_read_unlock();
1679
1680 task_cputime(tsk, &utime, &stime);
1681 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1682 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1683
1684 info.si_status = tsk->exit_code & 0x7f;
1685 if (tsk->exit_code & 0x80)
1686 info.si_code = CLD_DUMPED;
1687 else if (tsk->exit_code & 0x7f)
1688 info.si_code = CLD_KILLED;
1689 else {
1690 info.si_code = CLD_EXITED;
1691 info.si_status = tsk->exit_code >> 8;
1692 }
1693
1694 psig = tsk->parent->sighand;
1695 spin_lock_irqsave(&psig->siglock, flags);
1696 if (!tsk->ptrace && sig == SIGCHLD &&
1697 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1698 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1699 /*
1700 * We are exiting and our parent doesn't care. POSIX.1
1701 * defines special semantics for setting SIGCHLD to SIG_IGN
1702 * or setting the SA_NOCLDWAIT flag: we should be reaped
1703 * automatically and not left for our parent's wait4 call.
1704 * Rather than having the parent do it as a magic kind of
1705 * signal handler, we just set this to tell do_exit that we
1706 * can be cleaned up without becoming a zombie. Note that
1707 * we still call __wake_up_parent in this case, because a
1708 * blocked sys_wait4 might now return -ECHILD.
1709 *
1710 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1711 * is implementation-defined: we do (if you don't want
1712 * it, just use SIG_IGN instead).
1713 */
1714 autoreap = true;
1715 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1716 sig = 0;
1717 }
1718 if (valid_signal(sig) && sig)
1719 __group_send_sig_info(sig, &info, tsk->parent);
1720 __wake_up_parent(tsk, tsk->parent);
1721 spin_unlock_irqrestore(&psig->siglock, flags);
1722
1723 return autoreap;
1724}
1725
1726/**
1727 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1728 * @tsk: task reporting the state change
1729 * @for_ptracer: the notification is for ptracer
1730 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1731 *
1732 * Notify @tsk's parent that the stopped/continued state has changed. If
1733 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1734 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1735 *
1736 * CONTEXT:
1737 * Must be called with tasklist_lock at least read locked.
1738 */
1739static void do_notify_parent_cldstop(struct task_struct *tsk,
1740 bool for_ptracer, int why)
1741{
1742 struct siginfo info;
1743 unsigned long flags;
1744 struct task_struct *parent;
1745 struct sighand_struct *sighand;
1746 cputime_t utime, stime;
1747
1748 if (for_ptracer) {
1749 parent = tsk->parent;
1750 } else {
1751 tsk = tsk->group_leader;
1752 parent = tsk->real_parent;
1753 }
1754
1755 info.si_signo = SIGCHLD;
1756 info.si_errno = 0;
1757 /*
1758 * see comment in do_notify_parent() about the following 4 lines
1759 */
1760 rcu_read_lock();
1761 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1762 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1763 rcu_read_unlock();
1764
1765 task_cputime(tsk, &utime, &stime);
1766 info.si_utime = cputime_to_clock_t(utime);
1767 info.si_stime = cputime_to_clock_t(stime);
1768
1769 info.si_code = why;
1770 switch (why) {
1771 case CLD_CONTINUED:
1772 info.si_status = SIGCONT;
1773 break;
1774 case CLD_STOPPED:
1775 info.si_status = tsk->signal->group_exit_code & 0x7f;
1776 break;
1777 case CLD_TRAPPED:
1778 info.si_status = tsk->exit_code & 0x7f;
1779 break;
1780 default:
1781 BUG();
1782 }
1783
1784 sighand = parent->sighand;
1785 spin_lock_irqsave(&sighand->siglock, flags);
1786 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1787 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1788 __group_send_sig_info(SIGCHLD, &info, parent);
1789 /*
1790 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1791 */
1792 __wake_up_parent(tsk, parent);
1793 spin_unlock_irqrestore(&sighand->siglock, flags);
1794}
1795
1796static inline int may_ptrace_stop(void)
1797{
1798 if (!likely(current->ptrace))
1799 return 0;
1800 /*
1801 * Are we in the middle of do_coredump?
1802 * If so and our tracer is also part of the coredump stopping
1803 * is a deadlock situation, and pointless because our tracer
1804 * is dead so don't allow us to stop.
1805 * If SIGKILL was already sent before the caller unlocked
1806 * ->siglock we must see ->core_state != NULL. Otherwise it
1807 * is safe to enter schedule().
1808 *
1809 * This is almost outdated, a task with the pending SIGKILL can't
1810 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1811 * after SIGKILL was already dequeued.
1812 */
1813 if (unlikely(current->mm->core_state) &&
1814 unlikely(current->mm == current->parent->mm))
1815 return 0;
1816
1817 return 1;
1818}
1819
1820/*
1821 * Return non-zero if there is a SIGKILL that should be waking us up.
1822 * Called with the siglock held.
1823 */
1824static int sigkill_pending(struct task_struct *tsk)
1825{
1826 return sigismember(&tsk->pending.signal, SIGKILL) ||
1827 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1828}
1829
1830/*
1831 * This must be called with current->sighand->siglock held.
1832 *
1833 * This should be the path for all ptrace stops.
1834 * We always set current->last_siginfo while stopped here.
1835 * That makes it a way to test a stopped process for
1836 * being ptrace-stopped vs being job-control-stopped.
1837 *
1838 * If we actually decide not to stop at all because the tracer
1839 * is gone, we keep current->exit_code unless clear_code.
1840 */
1841static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1842 __releases(¤t->sighand->siglock)
1843 __acquires(¤t->sighand->siglock)
1844{
1845 bool gstop_done = false;
1846
1847 if (arch_ptrace_stop_needed(exit_code, info)) {
1848 /*
1849 * The arch code has something special to do before a
1850 * ptrace stop. This is allowed to block, e.g. for faults
1851 * on user stack pages. We can't keep the siglock while
1852 * calling arch_ptrace_stop, so we must release it now.
1853 * To preserve proper semantics, we must do this before
1854 * any signal bookkeeping like checking group_stop_count.
1855 * Meanwhile, a SIGKILL could come in before we retake the
1856 * siglock. That must prevent us from sleeping in TASK_TRACED.
1857 * So after regaining the lock, we must check for SIGKILL.
1858 */
1859 spin_unlock_irq(¤t->sighand->siglock);
1860 arch_ptrace_stop(exit_code, info);
1861 spin_lock_irq(¤t->sighand->siglock);
1862 if (sigkill_pending(current))
1863 return;
1864 }
1865
1866 /*
1867 * We're committing to trapping. TRACED should be visible before
1868 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1869 * Also, transition to TRACED and updates to ->jobctl should be
1870 * atomic with respect to siglock and should be done after the arch
1871 * hook as siglock is released and regrabbed across it.
1872 */
1873 set_current_state(TASK_TRACED);
1874
1875 current->last_siginfo = info;
1876 current->exit_code = exit_code;
1877
1878 /*
1879 * If @why is CLD_STOPPED, we're trapping to participate in a group
1880 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1881 * across siglock relocks since INTERRUPT was scheduled, PENDING
1882 * could be clear now. We act as if SIGCONT is received after
1883 * TASK_TRACED is entered - ignore it.
1884 */
1885 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1886 gstop_done = task_participate_group_stop(current);
1887
1888 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1889 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1890 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1891 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1892
1893 /* entering a trap, clear TRAPPING */
1894 task_clear_jobctl_trapping(current);
1895
1896 spin_unlock_irq(¤t->sighand->siglock);
1897 read_lock(&tasklist_lock);
1898 if (may_ptrace_stop()) {
1899 /*
1900 * Notify parents of the stop.
1901 *
1902 * While ptraced, there are two parents - the ptracer and
1903 * the real_parent of the group_leader. The ptracer should
1904 * know about every stop while the real parent is only
1905 * interested in the completion of group stop. The states
1906 * for the two don't interact with each other. Notify
1907 * separately unless they're gonna be duplicates.
1908 */
1909 do_notify_parent_cldstop(current, true, why);
1910 if (gstop_done && ptrace_reparented(current))
1911 do_notify_parent_cldstop(current, false, why);
1912
1913 /*
1914 * Don't want to allow preemption here, because
1915 * sys_ptrace() needs this task to be inactive.
1916 *
1917 * XXX: implement read_unlock_no_resched().
1918 */
1919 preempt_disable();
1920 read_unlock(&tasklist_lock);
1921 preempt_enable_no_resched();
1922 freezable_schedule();
1923 } else {
1924 /*
1925 * By the time we got the lock, our tracer went away.
1926 * Don't drop the lock yet, another tracer may come.
1927 *
1928 * If @gstop_done, the ptracer went away between group stop
1929 * completion and here. During detach, it would have set
1930 * JOBCTL_STOP_PENDING on us and we'll re-enter
1931 * TASK_STOPPED in do_signal_stop() on return, so notifying
1932 * the real parent of the group stop completion is enough.
1933 */
1934 if (gstop_done)
1935 do_notify_parent_cldstop(current, false, why);
1936
1937 /* tasklist protects us from ptrace_freeze_traced() */
1938 __set_current_state(TASK_RUNNING);
1939 if (clear_code)
1940 current->exit_code = 0;
1941 read_unlock(&tasklist_lock);
1942 }
1943
1944 /*
1945 * We are back. Now reacquire the siglock before touching
1946 * last_siginfo, so that we are sure to have synchronized with
1947 * any signal-sending on another CPU that wants to examine it.
1948 */
1949 spin_lock_irq(¤t->sighand->siglock);
1950 current->last_siginfo = NULL;
1951
1952 /* LISTENING can be set only during STOP traps, clear it */
1953 current->jobctl &= ~JOBCTL_LISTENING;
1954
1955 /*
1956 * Queued signals ignored us while we were stopped for tracing.
1957 * So check for any that we should take before resuming user mode.
1958 * This sets TIF_SIGPENDING, but never clears it.
1959 */
1960 recalc_sigpending_tsk(current);
1961}
1962
1963static void ptrace_do_notify(int signr, int exit_code, int why)
1964{
1965 siginfo_t info;
1966
1967 memset(&info, 0, sizeof info);
1968 info.si_signo = signr;
1969 info.si_code = exit_code;
1970 info.si_pid = task_pid_vnr(current);
1971 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1972
1973 /* Let the debugger run. */
1974 ptrace_stop(exit_code, why, 1, &info);
1975}
1976
1977void ptrace_notify(int exit_code)
1978{
1979 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1980 if (unlikely(current->task_works))
1981 task_work_run();
1982
1983 spin_lock_irq(¤t->sighand->siglock);
1984 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1985 spin_unlock_irq(¤t->sighand->siglock);
1986}
1987
1988/**
1989 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1990 * @signr: signr causing group stop if initiating
1991 *
1992 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1993 * and participate in it. If already set, participate in the existing
1994 * group stop. If participated in a group stop (and thus slept), %true is
1995 * returned with siglock released.
1996 *
1997 * If ptraced, this function doesn't handle stop itself. Instead,
1998 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1999 * untouched. The caller must ensure that INTERRUPT trap handling takes
2000 * places afterwards.
2001 *
2002 * CONTEXT:
2003 * Must be called with @current->sighand->siglock held, which is released
2004 * on %true return.
2005 *
2006 * RETURNS:
2007 * %false if group stop is already cancelled or ptrace trap is scheduled.
2008 * %true if participated in group stop.
2009 */
2010static bool do_signal_stop(int signr)
2011 __releases(¤t->sighand->siglock)
2012{
2013 struct signal_struct *sig = current->signal;
2014
2015 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2016 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2017 struct task_struct *t;
2018
2019 /* signr will be recorded in task->jobctl for retries */
2020 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2021
2022 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2023 unlikely(signal_group_exit(sig)))
2024 return false;
2025 /*
2026 * There is no group stop already in progress. We must
2027 * initiate one now.
2028 *
2029 * While ptraced, a task may be resumed while group stop is
2030 * still in effect and then receive a stop signal and
2031 * initiate another group stop. This deviates from the
2032 * usual behavior as two consecutive stop signals can't
2033 * cause two group stops when !ptraced. That is why we
2034 * also check !task_is_stopped(t) below.
2035 *
2036 * The condition can be distinguished by testing whether
2037 * SIGNAL_STOP_STOPPED is already set. Don't generate
2038 * group_exit_code in such case.
2039 *
2040 * This is not necessary for SIGNAL_STOP_CONTINUED because
2041 * an intervening stop signal is required to cause two
2042 * continued events regardless of ptrace.
2043 */
2044 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2045 sig->group_exit_code = signr;
2046
2047 sig->group_stop_count = 0;
2048
2049 if (task_set_jobctl_pending(current, signr | gstop))
2050 sig->group_stop_count++;
2051
2052 t = current;
2053 while_each_thread(current, t) {
2054 /*
2055 * Setting state to TASK_STOPPED for a group
2056 * stop is always done with the siglock held,
2057 * so this check has no races.
2058 */
2059 if (!task_is_stopped(t) &&
2060 task_set_jobctl_pending(t, signr | gstop)) {
2061 sig->group_stop_count++;
2062 if (likely(!(t->ptrace & PT_SEIZED)))
2063 signal_wake_up(t, 0);
2064 else
2065 ptrace_trap_notify(t);
2066 }
2067 }
2068 }
2069
2070 if (likely(!current->ptrace)) {
2071 int notify = 0;
2072
2073 /*
2074 * If there are no other threads in the group, or if there
2075 * is a group stop in progress and we are the last to stop,
2076 * report to the parent.
2077 */
2078 if (task_participate_group_stop(current))
2079 notify = CLD_STOPPED;
2080
2081 __set_current_state(TASK_STOPPED);
2082 spin_unlock_irq(¤t->sighand->siglock);
2083
2084 /*
2085 * Notify the parent of the group stop completion. Because
2086 * we're not holding either the siglock or tasklist_lock
2087 * here, ptracer may attach inbetween; however, this is for
2088 * group stop and should always be delivered to the real
2089 * parent of the group leader. The new ptracer will get
2090 * its notification when this task transitions into
2091 * TASK_TRACED.
2092 */
2093 if (notify) {
2094 read_lock(&tasklist_lock);
2095 do_notify_parent_cldstop(current, false, notify);
2096 read_unlock(&tasklist_lock);
2097 }
2098
2099 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2100 freezable_schedule();
2101 return true;
2102 } else {
2103 /*
2104 * While ptraced, group stop is handled by STOP trap.
2105 * Schedule it and let the caller deal with it.
2106 */
2107 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2108 return false;
2109 }
2110}
2111
2112/**
2113 * do_jobctl_trap - take care of ptrace jobctl traps
2114 *
2115 * When PT_SEIZED, it's used for both group stop and explicit
2116 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2117 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2118 * the stop signal; otherwise, %SIGTRAP.
2119 *
2120 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2121 * number as exit_code and no siginfo.
2122 *
2123 * CONTEXT:
2124 * Must be called with @current->sighand->siglock held, which may be
2125 * released and re-acquired before returning with intervening sleep.
2126 */
2127static void do_jobctl_trap(void)
2128{
2129 struct signal_struct *signal = current->signal;
2130 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2131
2132 if (current->ptrace & PT_SEIZED) {
2133 if (!signal->group_stop_count &&
2134 !(signal->flags & SIGNAL_STOP_STOPPED))
2135 signr = SIGTRAP;
2136 WARN_ON_ONCE(!signr);
2137 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2138 CLD_STOPPED);
2139 } else {
2140 WARN_ON_ONCE(!signr);
2141 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2142 current->exit_code = 0;
2143 }
2144}
2145
2146static int ptrace_signal(int signr, siginfo_t *info)
2147{
2148 ptrace_signal_deliver();
2149 /*
2150 * We do not check sig_kernel_stop(signr) but set this marker
2151 * unconditionally because we do not know whether debugger will
2152 * change signr. This flag has no meaning unless we are going
2153 * to stop after return from ptrace_stop(). In this case it will
2154 * be checked in do_signal_stop(), we should only stop if it was
2155 * not cleared by SIGCONT while we were sleeping. See also the
2156 * comment in dequeue_signal().
2157 */
2158 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2159 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2160
2161 /* We're back. Did the debugger cancel the sig? */
2162 signr = current->exit_code;
2163 if (signr == 0)
2164 return signr;
2165
2166 current->exit_code = 0;
2167
2168 /*
2169 * Update the siginfo structure if the signal has
2170 * changed. If the debugger wanted something
2171 * specific in the siginfo structure then it should
2172 * have updated *info via PTRACE_SETSIGINFO.
2173 */
2174 if (signr != info->si_signo) {
2175 info->si_signo = signr;
2176 info->si_errno = 0;
2177 info->si_code = SI_USER;
2178 rcu_read_lock();
2179 info->si_pid = task_pid_vnr(current->parent);
2180 info->si_uid = from_kuid_munged(current_user_ns(),
2181 task_uid(current->parent));
2182 rcu_read_unlock();
2183 }
2184
2185 /* If the (new) signal is now blocked, requeue it. */
2186 if (sigismember(¤t->blocked, signr)) {
2187 specific_send_sig_info(signr, info, current);
2188 signr = 0;
2189 }
2190
2191 return signr;
2192}
2193
2194int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2195 struct pt_regs *regs, void *cookie)
2196{
2197 struct sighand_struct *sighand = current->sighand;
2198 struct signal_struct *signal = current->signal;
2199 int signr;
2200
2201 if (unlikely(current->task_works))
2202 task_work_run();
2203
2204 if (unlikely(uprobe_deny_signal()))
2205 return 0;
2206
2207 /*
2208 * Do this once, we can't return to user-mode if freezing() == T.
2209 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2210 * thus do not need another check after return.
2211 */
2212 try_to_freeze();
2213
2214relock:
2215 spin_lock_irq(&sighand->siglock);
2216 /*
2217 * Every stopped thread goes here after wakeup. Check to see if
2218 * we should notify the parent, prepare_signal(SIGCONT) encodes
2219 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2220 */
2221 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2222 int why;
2223
2224 if (signal->flags & SIGNAL_CLD_CONTINUED)
2225 why = CLD_CONTINUED;
2226 else
2227 why = CLD_STOPPED;
2228
2229 signal->flags &= ~SIGNAL_CLD_MASK;
2230
2231 spin_unlock_irq(&sighand->siglock);
2232
2233 /*
2234 * Notify the parent that we're continuing. This event is
2235 * always per-process and doesn't make whole lot of sense
2236 * for ptracers, who shouldn't consume the state via
2237 * wait(2) either, but, for backward compatibility, notify
2238 * the ptracer of the group leader too unless it's gonna be
2239 * a duplicate.
2240 */
2241 read_lock(&tasklist_lock);
2242 do_notify_parent_cldstop(current, false, why);
2243
2244 if (ptrace_reparented(current->group_leader))
2245 do_notify_parent_cldstop(current->group_leader,
2246 true, why);
2247 read_unlock(&tasklist_lock);
2248
2249 goto relock;
2250 }
2251
2252 for (;;) {
2253 struct k_sigaction *ka;
2254
2255 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2256 do_signal_stop(0))
2257 goto relock;
2258
2259 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2260 do_jobctl_trap();
2261 spin_unlock_irq(&sighand->siglock);
2262 goto relock;
2263 }
2264
2265 signr = dequeue_signal(current, ¤t->blocked, info);
2266
2267 if (!signr)
2268 break; /* will return 0 */
2269
2270 if (unlikely(current->ptrace) && signr != SIGKILL) {
2271 signr = ptrace_signal(signr, info);
2272 if (!signr)
2273 continue;
2274 }
2275
2276 ka = &sighand->action[signr-1];
2277
2278 /* Trace actually delivered signals. */
2279 trace_signal_deliver(signr, info, ka);
2280
2281 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2282 continue;
2283 if (ka->sa.sa_handler != SIG_DFL) {
2284 /* Run the handler. */
2285 *return_ka = *ka;
2286
2287 if (ka->sa.sa_flags & SA_ONESHOT)
2288 ka->sa.sa_handler = SIG_DFL;
2289
2290 break; /* will return non-zero "signr" value */
2291 }
2292
2293 /*
2294 * Now we are doing the default action for this signal.
2295 */
2296 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2297 continue;
2298
2299 /*
2300 * Global init gets no signals it doesn't want.
2301 * Container-init gets no signals it doesn't want from same
2302 * container.
2303 *
2304 * Note that if global/container-init sees a sig_kernel_only()
2305 * signal here, the signal must have been generated internally
2306 * or must have come from an ancestor namespace. In either
2307 * case, the signal cannot be dropped.
2308 */
2309 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2310 !sig_kernel_only(signr))
2311 continue;
2312
2313 if (sig_kernel_stop(signr)) {
2314 /*
2315 * The default action is to stop all threads in
2316 * the thread group. The job control signals
2317 * do nothing in an orphaned pgrp, but SIGSTOP
2318 * always works. Note that siglock needs to be
2319 * dropped during the call to is_orphaned_pgrp()
2320 * because of lock ordering with tasklist_lock.
2321 * This allows an intervening SIGCONT to be posted.
2322 * We need to check for that and bail out if necessary.
2323 */
2324 if (signr != SIGSTOP) {
2325 spin_unlock_irq(&sighand->siglock);
2326
2327 /* signals can be posted during this window */
2328
2329 if (is_current_pgrp_orphaned())
2330 goto relock;
2331
2332 spin_lock_irq(&sighand->siglock);
2333 }
2334
2335 if (likely(do_signal_stop(info->si_signo))) {
2336 /* It released the siglock. */
2337 goto relock;
2338 }
2339
2340 /*
2341 * We didn't actually stop, due to a race
2342 * with SIGCONT or something like that.
2343 */
2344 continue;
2345 }
2346
2347 spin_unlock_irq(&sighand->siglock);
2348
2349 /*
2350 * Anything else is fatal, maybe with a core dump.
2351 */
2352 current->flags |= PF_SIGNALED;
2353
2354 if (sig_kernel_coredump(signr)) {
2355 if (print_fatal_signals)
2356 print_fatal_signal(info->si_signo);
2357 proc_coredump_connector(current);
2358 /*
2359 * If it was able to dump core, this kills all
2360 * other threads in the group and synchronizes with
2361 * their demise. If we lost the race with another
2362 * thread getting here, it set group_exit_code
2363 * first and our do_group_exit call below will use
2364 * that value and ignore the one we pass it.
2365 */
2366 do_coredump(info);
2367 }
2368
2369 /*
2370 * Death signals, no core dump.
2371 */
2372 do_group_exit(info->si_signo);
2373 /* NOTREACHED */
2374 }
2375 spin_unlock_irq(&sighand->siglock);
2376 return signr;
2377}
2378
2379/**
2380 * signal_delivered -
2381 * @sig: number of signal being delivered
2382 * @info: siginfo_t of signal being delivered
2383 * @ka: sigaction setting that chose the handler
2384 * @regs: user register state
2385 * @stepping: nonzero if debugger single-step or block-step in use
2386 *
2387 * This function should be called when a signal has successfully been
2388 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2389 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2390 * is set in @ka->sa.sa_flags. Tracing is notified.
2391 */
2392void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2393 struct pt_regs *regs, int stepping)
2394{
2395 sigset_t blocked;
2396
2397 /* A signal was successfully delivered, and the
2398 saved sigmask was stored on the signal frame,
2399 and will be restored by sigreturn. So we can
2400 simply clear the restore sigmask flag. */
2401 clear_restore_sigmask();
2402
2403 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2404 if (!(ka->sa.sa_flags & SA_NODEFER))
2405 sigaddset(&blocked, sig);
2406 set_current_blocked(&blocked);
2407 tracehook_signal_handler(sig, info, ka, regs, stepping);
2408}
2409
2410void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2411{
2412 if (failed)
2413 force_sigsegv(ksig->sig, current);
2414 else
2415 signal_delivered(ksig->sig, &ksig->info, &ksig->ka,
2416 signal_pt_regs(), stepping);
2417}
2418
2419/*
2420 * It could be that complete_signal() picked us to notify about the
2421 * group-wide signal. Other threads should be notified now to take
2422 * the shared signals in @which since we will not.
2423 */
2424static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2425{
2426 sigset_t retarget;
2427 struct task_struct *t;
2428
2429 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2430 if (sigisemptyset(&retarget))
2431 return;
2432
2433 t = tsk;
2434 while_each_thread(tsk, t) {
2435 if (t->flags & PF_EXITING)
2436 continue;
2437
2438 if (!has_pending_signals(&retarget, &t->blocked))
2439 continue;
2440 /* Remove the signals this thread can handle. */
2441 sigandsets(&retarget, &retarget, &t->blocked);
2442
2443 if (!signal_pending(t))
2444 signal_wake_up(t, 0);
2445
2446 if (sigisemptyset(&retarget))
2447 break;
2448 }
2449}
2450
2451void exit_signals(struct task_struct *tsk)
2452{
2453 int group_stop = 0;
2454 sigset_t unblocked;
2455
2456 /*
2457 * @tsk is about to have PF_EXITING set - lock out users which
2458 * expect stable threadgroup.
2459 */
2460 threadgroup_change_begin(tsk);
2461
2462 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2463 tsk->flags |= PF_EXITING;
2464 threadgroup_change_end(tsk);
2465 return;
2466 }
2467
2468 spin_lock_irq(&tsk->sighand->siglock);
2469 /*
2470 * From now this task is not visible for group-wide signals,
2471 * see wants_signal(), do_signal_stop().
2472 */
2473 tsk->flags |= PF_EXITING;
2474
2475 threadgroup_change_end(tsk);
2476
2477 if (!signal_pending(tsk))
2478 goto out;
2479
2480 unblocked = tsk->blocked;
2481 signotset(&unblocked);
2482 retarget_shared_pending(tsk, &unblocked);
2483
2484 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2485 task_participate_group_stop(tsk))
2486 group_stop = CLD_STOPPED;
2487out:
2488 spin_unlock_irq(&tsk->sighand->siglock);
2489
2490 /*
2491 * If group stop has completed, deliver the notification. This
2492 * should always go to the real parent of the group leader.
2493 */
2494 if (unlikely(group_stop)) {
2495 read_lock(&tasklist_lock);
2496 do_notify_parent_cldstop(tsk, false, group_stop);
2497 read_unlock(&tasklist_lock);
2498 }
2499}
2500
2501EXPORT_SYMBOL(recalc_sigpending);
2502EXPORT_SYMBOL_GPL(dequeue_signal);
2503EXPORT_SYMBOL(flush_signals);
2504EXPORT_SYMBOL(force_sig);
2505EXPORT_SYMBOL(send_sig);
2506EXPORT_SYMBOL(send_sig_info);
2507EXPORT_SYMBOL(sigprocmask);
2508EXPORT_SYMBOL(block_all_signals);
2509EXPORT_SYMBOL(unblock_all_signals);
2510
2511
2512/*
2513 * System call entry points.
2514 */
2515
2516/**
2517 * sys_restart_syscall - restart a system call
2518 */
2519SYSCALL_DEFINE0(restart_syscall)
2520{
2521 struct restart_block *restart = ¤t_thread_info()->restart_block;
2522 return restart->fn(restart);
2523}
2524
2525long do_no_restart_syscall(struct restart_block *param)
2526{
2527 return -EINTR;
2528}
2529
2530static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2531{
2532 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2533 sigset_t newblocked;
2534 /* A set of now blocked but previously unblocked signals. */
2535 sigandnsets(&newblocked, newset, ¤t->blocked);
2536 retarget_shared_pending(tsk, &newblocked);
2537 }
2538 tsk->blocked = *newset;
2539 recalc_sigpending();
2540}
2541
2542/**
2543 * set_current_blocked - change current->blocked mask
2544 * @newset: new mask
2545 *
2546 * It is wrong to change ->blocked directly, this helper should be used
2547 * to ensure the process can't miss a shared signal we are going to block.
2548 */
2549void set_current_blocked(sigset_t *newset)
2550{
2551 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2552 __set_current_blocked(newset);
2553}
2554
2555void __set_current_blocked(const sigset_t *newset)
2556{
2557 struct task_struct *tsk = current;
2558
2559 spin_lock_irq(&tsk->sighand->siglock);
2560 __set_task_blocked(tsk, newset);
2561 spin_unlock_irq(&tsk->sighand->siglock);
2562}
2563
2564/*
2565 * This is also useful for kernel threads that want to temporarily
2566 * (or permanently) block certain signals.
2567 *
2568 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2569 * interface happily blocks "unblockable" signals like SIGKILL
2570 * and friends.
2571 */
2572int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2573{
2574 struct task_struct *tsk = current;
2575 sigset_t newset;
2576
2577 /* Lockless, only current can change ->blocked, never from irq */
2578 if (oldset)
2579 *oldset = tsk->blocked;
2580
2581 switch (how) {
2582 case SIG_BLOCK:
2583 sigorsets(&newset, &tsk->blocked, set);
2584 break;
2585 case SIG_UNBLOCK:
2586 sigandnsets(&newset, &tsk->blocked, set);
2587 break;
2588 case SIG_SETMASK:
2589 newset = *set;
2590 break;
2591 default:
2592 return -EINVAL;
2593 }
2594
2595 __set_current_blocked(&newset);
2596 return 0;
2597}
2598
2599/**
2600 * sys_rt_sigprocmask - change the list of currently blocked signals
2601 * @how: whether to add, remove, or set signals
2602 * @nset: stores pending signals
2603 * @oset: previous value of signal mask if non-null
2604 * @sigsetsize: size of sigset_t type
2605 */
2606SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2607 sigset_t __user *, oset, size_t, sigsetsize)
2608{
2609 sigset_t old_set, new_set;
2610 int error;
2611
2612 /* XXX: Don't preclude handling different sized sigset_t's. */
2613 if (sigsetsize != sizeof(sigset_t))
2614 return -EINVAL;
2615
2616 old_set = current->blocked;
2617
2618 if (nset) {
2619 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2620 return -EFAULT;
2621 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2622
2623 error = sigprocmask(how, &new_set, NULL);
2624 if (error)
2625 return error;
2626 }
2627
2628 if (oset) {
2629 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2630 return -EFAULT;
2631 }
2632
2633 return 0;
2634}
2635
2636#ifdef CONFIG_COMPAT
2637COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2638 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2639{
2640#ifdef __BIG_ENDIAN
2641 sigset_t old_set = current->blocked;
2642
2643 /* XXX: Don't preclude handling different sized sigset_t's. */
2644 if (sigsetsize != sizeof(sigset_t))
2645 return -EINVAL;
2646
2647 if (nset) {
2648 compat_sigset_t new32;
2649 sigset_t new_set;
2650 int error;
2651 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2652 return -EFAULT;
2653
2654 sigset_from_compat(&new_set, &new32);
2655 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2656
2657 error = sigprocmask(how, &new_set, NULL);
2658 if (error)
2659 return error;
2660 }
2661 if (oset) {
2662 compat_sigset_t old32;
2663 sigset_to_compat(&old32, &old_set);
2664 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2665 return -EFAULT;
2666 }
2667 return 0;
2668#else
2669 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2670 (sigset_t __user *)oset, sigsetsize);
2671#endif
2672}
2673#endif
2674
2675static int do_sigpending(void *set, unsigned long sigsetsize)
2676{
2677 if (sigsetsize > sizeof(sigset_t))
2678 return -EINVAL;
2679
2680 spin_lock_irq(¤t->sighand->siglock);
2681 sigorsets(set, ¤t->pending.signal,
2682 ¤t->signal->shared_pending.signal);
2683 spin_unlock_irq(¤t->sighand->siglock);
2684
2685 /* Outside the lock because only this thread touches it. */
2686 sigandsets(set, ¤t->blocked, set);
2687 return 0;
2688}
2689
2690/**
2691 * sys_rt_sigpending - examine a pending signal that has been raised
2692 * while blocked
2693 * @uset: stores pending signals
2694 * @sigsetsize: size of sigset_t type or larger
2695 */
2696SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2697{
2698 sigset_t set;
2699 int err = do_sigpending(&set, sigsetsize);
2700 if (!err && copy_to_user(uset, &set, sigsetsize))
2701 err = -EFAULT;
2702 return err;
2703}
2704
2705#ifdef CONFIG_COMPAT
2706COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2707 compat_size_t, sigsetsize)
2708{
2709#ifdef __BIG_ENDIAN
2710 sigset_t set;
2711 int err = do_sigpending(&set, sigsetsize);
2712 if (!err) {
2713 compat_sigset_t set32;
2714 sigset_to_compat(&set32, &set);
2715 /* we can get here only if sigsetsize <= sizeof(set) */
2716 if (copy_to_user(uset, &set32, sigsetsize))
2717 err = -EFAULT;
2718 }
2719 return err;
2720#else
2721 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2722#endif
2723}
2724#endif
2725
2726#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2727
2728int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2729{
2730 int err;
2731
2732 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2733 return -EFAULT;
2734 if (from->si_code < 0)
2735 return __copy_to_user(to, from, sizeof(siginfo_t))
2736 ? -EFAULT : 0;
2737 /*
2738 * If you change siginfo_t structure, please be sure
2739 * this code is fixed accordingly.
2740 * Please remember to update the signalfd_copyinfo() function
2741 * inside fs/signalfd.c too, in case siginfo_t changes.
2742 * It should never copy any pad contained in the structure
2743 * to avoid security leaks, but must copy the generic
2744 * 3 ints plus the relevant union member.
2745 */
2746 err = __put_user(from->si_signo, &to->si_signo);
2747 err |= __put_user(from->si_errno, &to->si_errno);
2748 err |= __put_user((short)from->si_code, &to->si_code);
2749 switch (from->si_code & __SI_MASK) {
2750 case __SI_KILL:
2751 err |= __put_user(from->si_pid, &to->si_pid);
2752 err |= __put_user(from->si_uid, &to->si_uid);
2753 break;
2754 case __SI_TIMER:
2755 err |= __put_user(from->si_tid, &to->si_tid);
2756 err |= __put_user(from->si_overrun, &to->si_overrun);
2757 err |= __put_user(from->si_ptr, &to->si_ptr);
2758 break;
2759 case __SI_POLL:
2760 err |= __put_user(from->si_band, &to->si_band);
2761 err |= __put_user(from->si_fd, &to->si_fd);
2762 break;
2763 case __SI_FAULT:
2764 err |= __put_user(from->si_addr, &to->si_addr);
2765#ifdef __ARCH_SI_TRAPNO
2766 err |= __put_user(from->si_trapno, &to->si_trapno);
2767#endif
2768#ifdef BUS_MCEERR_AO
2769 /*
2770 * Other callers might not initialize the si_lsb field,
2771 * so check explicitly for the right codes here.
2772 */
2773 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2774 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2775#endif
2776 break;
2777 case __SI_CHLD:
2778 err |= __put_user(from->si_pid, &to->si_pid);
2779 err |= __put_user(from->si_uid, &to->si_uid);
2780 err |= __put_user(from->si_status, &to->si_status);
2781 err |= __put_user(from->si_utime, &to->si_utime);
2782 err |= __put_user(from->si_stime, &to->si_stime);
2783 break;
2784 case __SI_RT: /* This is not generated by the kernel as of now. */
2785 case __SI_MESGQ: /* But this is */
2786 err |= __put_user(from->si_pid, &to->si_pid);
2787 err |= __put_user(from->si_uid, &to->si_uid);
2788 err |= __put_user(from->si_ptr, &to->si_ptr);
2789 break;
2790#ifdef __ARCH_SIGSYS
2791 case __SI_SYS:
2792 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2793 err |= __put_user(from->si_syscall, &to->si_syscall);
2794 err |= __put_user(from->si_arch, &to->si_arch);
2795 break;
2796#endif
2797 default: /* this is just in case for now ... */
2798 err |= __put_user(from->si_pid, &to->si_pid);
2799 err |= __put_user(from->si_uid, &to->si_uid);
2800 break;
2801 }
2802 return err;
2803}
2804
2805#endif
2806
2807/**
2808 * do_sigtimedwait - wait for queued signals specified in @which
2809 * @which: queued signals to wait for
2810 * @info: if non-null, the signal's siginfo is returned here
2811 * @ts: upper bound on process time suspension
2812 */
2813int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2814 const struct timespec *ts)
2815{
2816 struct task_struct *tsk = current;
2817 long timeout = MAX_SCHEDULE_TIMEOUT;
2818 sigset_t mask = *which;
2819 int sig;
2820
2821 if (ts) {
2822 if (!timespec_valid(ts))
2823 return -EINVAL;
2824 timeout = timespec_to_jiffies(ts);
2825 /*
2826 * We can be close to the next tick, add another one
2827 * to ensure we will wait at least the time asked for.
2828 */
2829 if (ts->tv_sec || ts->tv_nsec)
2830 timeout++;
2831 }
2832
2833 /*
2834 * Invert the set of allowed signals to get those we want to block.
2835 */
2836 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2837 signotset(&mask);
2838
2839 spin_lock_irq(&tsk->sighand->siglock);
2840 sig = dequeue_signal(tsk, &mask, info);
2841 if (!sig && timeout) {
2842 /*
2843 * None ready, temporarily unblock those we're interested
2844 * while we are sleeping in so that we'll be awakened when
2845 * they arrive. Unblocking is always fine, we can avoid
2846 * set_current_blocked().
2847 */
2848 tsk->real_blocked = tsk->blocked;
2849 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2850 recalc_sigpending();
2851 spin_unlock_irq(&tsk->sighand->siglock);
2852
2853 timeout = freezable_schedule_timeout_interruptible(timeout);
2854
2855 spin_lock_irq(&tsk->sighand->siglock);
2856 __set_task_blocked(tsk, &tsk->real_blocked);
2857 siginitset(&tsk->real_blocked, 0);
2858 sig = dequeue_signal(tsk, &mask, info);
2859 }
2860 spin_unlock_irq(&tsk->sighand->siglock);
2861
2862 if (sig)
2863 return sig;
2864 return timeout ? -EINTR : -EAGAIN;
2865}
2866
2867/**
2868 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2869 * in @uthese
2870 * @uthese: queued signals to wait for
2871 * @uinfo: if non-null, the signal's siginfo is returned here
2872 * @uts: upper bound on process time suspension
2873 * @sigsetsize: size of sigset_t type
2874 */
2875SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2876 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2877 size_t, sigsetsize)
2878{
2879 sigset_t these;
2880 struct timespec ts;
2881 siginfo_t info;
2882 int ret;
2883
2884 /* XXX: Don't preclude handling different sized sigset_t's. */
2885 if (sigsetsize != sizeof(sigset_t))
2886 return -EINVAL;
2887
2888 if (copy_from_user(&these, uthese, sizeof(these)))
2889 return -EFAULT;
2890
2891 if (uts) {
2892 if (copy_from_user(&ts, uts, sizeof(ts)))
2893 return -EFAULT;
2894 }
2895
2896 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2897
2898 if (ret > 0 && uinfo) {
2899 if (copy_siginfo_to_user(uinfo, &info))
2900 ret = -EFAULT;
2901 }
2902
2903 return ret;
2904}
2905
2906/**
2907 * sys_kill - send a signal to a process
2908 * @pid: the PID of the process
2909 * @sig: signal to be sent
2910 */
2911SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2912{
2913 struct siginfo info;
2914
2915 info.si_signo = sig;
2916 info.si_errno = 0;
2917 info.si_code = SI_USER;
2918 info.si_pid = task_tgid_vnr(current);
2919 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2920
2921 return kill_something_info(sig, &info, pid);
2922}
2923
2924static int
2925do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2926{
2927 struct task_struct *p;
2928 int error = -ESRCH;
2929
2930 rcu_read_lock();
2931 p = find_task_by_vpid(pid);
2932 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2933 error = check_kill_permission(sig, info, p);
2934 /*
2935 * The null signal is a permissions and process existence
2936 * probe. No signal is actually delivered.
2937 */
2938 if (!error && sig) {
2939 error = do_send_sig_info(sig, info, p, false);
2940 /*
2941 * If lock_task_sighand() failed we pretend the task
2942 * dies after receiving the signal. The window is tiny,
2943 * and the signal is private anyway.
2944 */
2945 if (unlikely(error == -ESRCH))
2946 error = 0;
2947 }
2948 }
2949 rcu_read_unlock();
2950
2951 return error;
2952}
2953
2954static int do_tkill(pid_t tgid, pid_t pid, int sig)
2955{
2956 struct siginfo info = {};
2957
2958 info.si_signo = sig;
2959 info.si_errno = 0;
2960 info.si_code = SI_TKILL;
2961 info.si_pid = task_tgid_vnr(current);
2962 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2963
2964 return do_send_specific(tgid, pid, sig, &info);
2965}
2966
2967/**
2968 * sys_tgkill - send signal to one specific thread
2969 * @tgid: the thread group ID of the thread
2970 * @pid: the PID of the thread
2971 * @sig: signal to be sent
2972 *
2973 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2974 * exists but it's not belonging to the target process anymore. This
2975 * method solves the problem of threads exiting and PIDs getting reused.
2976 */
2977SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2978{
2979 /* This is only valid for single tasks */
2980 if (pid <= 0 || tgid <= 0)
2981 return -EINVAL;
2982
2983 return do_tkill(tgid, pid, sig);
2984}
2985
2986/**
2987 * sys_tkill - send signal to one specific task
2988 * @pid: the PID of the task
2989 * @sig: signal to be sent
2990 *
2991 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2992 */
2993SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2994{
2995 /* This is only valid for single tasks */
2996 if (pid <= 0)
2997 return -EINVAL;
2998
2999 return do_tkill(0, pid, sig);
3000}
3001
3002static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3003{
3004 /* Not even root can pretend to send signals from the kernel.
3005 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3006 */
3007 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3008 (task_pid_vnr(current) != pid)) {
3009 /* We used to allow any < 0 si_code */
3010 WARN_ON_ONCE(info->si_code < 0);
3011 return -EPERM;
3012 }
3013 info->si_signo = sig;
3014
3015 /* POSIX.1b doesn't mention process groups. */
3016 return kill_proc_info(sig, info, pid);
3017}
3018
3019/**
3020 * sys_rt_sigqueueinfo - send signal information to a signal
3021 * @pid: the PID of the thread
3022 * @sig: signal to be sent
3023 * @uinfo: signal info to be sent
3024 */
3025SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3026 siginfo_t __user *, uinfo)
3027{
3028 siginfo_t info;
3029 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3030 return -EFAULT;
3031 return do_rt_sigqueueinfo(pid, sig, &info);
3032}
3033
3034#ifdef CONFIG_COMPAT
3035COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3036 compat_pid_t, pid,
3037 int, sig,
3038 struct compat_siginfo __user *, uinfo)
3039{
3040 siginfo_t info;
3041 int ret = copy_siginfo_from_user32(&info, uinfo);
3042 if (unlikely(ret))
3043 return ret;
3044 return do_rt_sigqueueinfo(pid, sig, &info);
3045}
3046#endif
3047
3048static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3049{
3050 /* This is only valid for single tasks */
3051 if (pid <= 0 || tgid <= 0)
3052 return -EINVAL;
3053
3054 /* Not even root can pretend to send signals from the kernel.
3055 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3056 */
3057 if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
3058 (task_pid_vnr(current) != pid)) {
3059 /* We used to allow any < 0 si_code */
3060 WARN_ON_ONCE(info->si_code < 0);
3061 return -EPERM;
3062 }
3063 info->si_signo = sig;
3064
3065 return do_send_specific(tgid, pid, sig, info);
3066}
3067
3068SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3069 siginfo_t __user *, uinfo)
3070{
3071 siginfo_t info;
3072
3073 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3074 return -EFAULT;
3075
3076 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3077}
3078
3079#ifdef CONFIG_COMPAT
3080COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3081 compat_pid_t, tgid,
3082 compat_pid_t, pid,
3083 int, sig,
3084 struct compat_siginfo __user *, uinfo)
3085{
3086 siginfo_t info;
3087
3088 if (copy_siginfo_from_user32(&info, uinfo))
3089 return -EFAULT;
3090 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3091}
3092#endif
3093
3094int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3095{
3096 struct task_struct *t = current;
3097 struct k_sigaction *k;
3098 sigset_t mask;
3099
3100 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3101 return -EINVAL;
3102
3103 k = &t->sighand->action[sig-1];
3104
3105 spin_lock_irq(¤t->sighand->siglock);
3106 if (oact)
3107 *oact = *k;
3108
3109 if (act) {
3110 sigdelsetmask(&act->sa.sa_mask,
3111 sigmask(SIGKILL) | sigmask(SIGSTOP));
3112 *k = *act;
3113 /*
3114 * POSIX 3.3.1.3:
3115 * "Setting a signal action to SIG_IGN for a signal that is
3116 * pending shall cause the pending signal to be discarded,
3117 * whether or not it is blocked."
3118 *
3119 * "Setting a signal action to SIG_DFL for a signal that is
3120 * pending and whose default action is to ignore the signal
3121 * (for example, SIGCHLD), shall cause the pending signal to
3122 * be discarded, whether or not it is blocked"
3123 */
3124 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3125 sigemptyset(&mask);
3126 sigaddset(&mask, sig);
3127 rm_from_queue_full(&mask, &t->signal->shared_pending);
3128 do {
3129 rm_from_queue_full(&mask, &t->pending);
3130 } while_each_thread(current, t);
3131 }
3132 }
3133
3134 spin_unlock_irq(¤t->sighand->siglock);
3135 return 0;
3136}
3137
3138static int
3139do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3140{
3141 stack_t oss;
3142 int error;
3143
3144 oss.ss_sp = (void __user *) current->sas_ss_sp;
3145 oss.ss_size = current->sas_ss_size;
3146 oss.ss_flags = sas_ss_flags(sp);
3147
3148 if (uss) {
3149 void __user *ss_sp;
3150 size_t ss_size;
3151 int ss_flags;
3152
3153 error = -EFAULT;
3154 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3155 goto out;
3156 error = __get_user(ss_sp, &uss->ss_sp) |
3157 __get_user(ss_flags, &uss->ss_flags) |
3158 __get_user(ss_size, &uss->ss_size);
3159 if (error)
3160 goto out;
3161
3162 error = -EPERM;
3163 if (on_sig_stack(sp))
3164 goto out;
3165
3166 error = -EINVAL;
3167 /*
3168 * Note - this code used to test ss_flags incorrectly:
3169 * old code may have been written using ss_flags==0
3170 * to mean ss_flags==SS_ONSTACK (as this was the only
3171 * way that worked) - this fix preserves that older
3172 * mechanism.
3173 */
3174 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3175 goto out;
3176
3177 if (ss_flags == SS_DISABLE) {
3178 ss_size = 0;
3179 ss_sp = NULL;
3180 } else {
3181 error = -ENOMEM;
3182 if (ss_size < MINSIGSTKSZ)
3183 goto out;
3184 }
3185
3186 current->sas_ss_sp = (unsigned long) ss_sp;
3187 current->sas_ss_size = ss_size;
3188 }
3189
3190 error = 0;
3191 if (uoss) {
3192 error = -EFAULT;
3193 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3194 goto out;
3195 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3196 __put_user(oss.ss_size, &uoss->ss_size) |
3197 __put_user(oss.ss_flags, &uoss->ss_flags);
3198 }
3199
3200out:
3201 return error;
3202}
3203SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3204{
3205 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3206}
3207
3208int restore_altstack(const stack_t __user *uss)
3209{
3210 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3211 /* squash all but EFAULT for now */
3212 return err == -EFAULT ? err : 0;
3213}
3214
3215int __save_altstack(stack_t __user *uss, unsigned long sp)
3216{
3217 struct task_struct *t = current;
3218 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3219 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3220 __put_user(t->sas_ss_size, &uss->ss_size);
3221}
3222
3223#ifdef CONFIG_COMPAT
3224COMPAT_SYSCALL_DEFINE2(sigaltstack,
3225 const compat_stack_t __user *, uss_ptr,
3226 compat_stack_t __user *, uoss_ptr)
3227{
3228 stack_t uss, uoss;
3229 int ret;
3230 mm_segment_t seg;
3231
3232 if (uss_ptr) {
3233 compat_stack_t uss32;
3234
3235 memset(&uss, 0, sizeof(stack_t));
3236 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3237 return -EFAULT;
3238 uss.ss_sp = compat_ptr(uss32.ss_sp);
3239 uss.ss_flags = uss32.ss_flags;
3240 uss.ss_size = uss32.ss_size;
3241 }
3242 seg = get_fs();
3243 set_fs(KERNEL_DS);
3244 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3245 (stack_t __force __user *) &uoss,
3246 compat_user_stack_pointer());
3247 set_fs(seg);
3248 if (ret >= 0 && uoss_ptr) {
3249 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3250 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3251 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3252 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3253 ret = -EFAULT;
3254 }
3255 return ret;
3256}
3257
3258int compat_restore_altstack(const compat_stack_t __user *uss)
3259{
3260 int err = compat_sys_sigaltstack(uss, NULL);
3261 /* squash all but -EFAULT for now */
3262 return err == -EFAULT ? err : 0;
3263}
3264
3265int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3266{
3267 struct task_struct *t = current;
3268 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3269 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3270 __put_user(t->sas_ss_size, &uss->ss_size);
3271}
3272#endif
3273
3274#ifdef __ARCH_WANT_SYS_SIGPENDING
3275
3276/**
3277 * sys_sigpending - examine pending signals
3278 * @set: where mask of pending signal is returned
3279 */
3280SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3281{
3282 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3283}
3284
3285#endif
3286
3287#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3288/**
3289 * sys_sigprocmask - examine and change blocked signals
3290 * @how: whether to add, remove, or set signals
3291 * @nset: signals to add or remove (if non-null)
3292 * @oset: previous value of signal mask if non-null
3293 *
3294 * Some platforms have their own version with special arguments;
3295 * others support only sys_rt_sigprocmask.
3296 */
3297
3298SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3299 old_sigset_t __user *, oset)
3300{
3301 old_sigset_t old_set, new_set;
3302 sigset_t new_blocked;
3303
3304 old_set = current->blocked.sig[0];
3305
3306 if (nset) {
3307 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3308 return -EFAULT;
3309
3310 new_blocked = current->blocked;
3311
3312 switch (how) {
3313 case SIG_BLOCK:
3314 sigaddsetmask(&new_blocked, new_set);
3315 break;
3316 case SIG_UNBLOCK:
3317 sigdelsetmask(&new_blocked, new_set);
3318 break;
3319 case SIG_SETMASK:
3320 new_blocked.sig[0] = new_set;
3321 break;
3322 default:
3323 return -EINVAL;
3324 }
3325
3326 set_current_blocked(&new_blocked);
3327 }
3328
3329 if (oset) {
3330 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3331 return -EFAULT;
3332 }
3333
3334 return 0;
3335}
3336#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3337
3338#ifndef CONFIG_ODD_RT_SIGACTION
3339/**
3340 * sys_rt_sigaction - alter an action taken by a process
3341 * @sig: signal to be sent
3342 * @act: new sigaction
3343 * @oact: used to save the previous sigaction
3344 * @sigsetsize: size of sigset_t type
3345 */
3346SYSCALL_DEFINE4(rt_sigaction, int, sig,
3347 const struct sigaction __user *, act,
3348 struct sigaction __user *, oact,
3349 size_t, sigsetsize)
3350{
3351 struct k_sigaction new_sa, old_sa;
3352 int ret = -EINVAL;
3353
3354 /* XXX: Don't preclude handling different sized sigset_t's. */
3355 if (sigsetsize != sizeof(sigset_t))
3356 goto out;
3357
3358 if (act) {
3359 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3360 return -EFAULT;
3361 }
3362
3363 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3364
3365 if (!ret && oact) {
3366 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3367 return -EFAULT;
3368 }
3369out:
3370 return ret;
3371}
3372#ifdef CONFIG_COMPAT
3373COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3374 const struct compat_sigaction __user *, act,
3375 struct compat_sigaction __user *, oact,
3376 compat_size_t, sigsetsize)
3377{
3378 struct k_sigaction new_ka, old_ka;
3379 compat_sigset_t mask;
3380#ifdef __ARCH_HAS_SA_RESTORER
3381 compat_uptr_t restorer;
3382#endif
3383 int ret;
3384
3385 /* XXX: Don't preclude handling different sized sigset_t's. */
3386 if (sigsetsize != sizeof(compat_sigset_t))
3387 return -EINVAL;
3388
3389 if (act) {
3390 compat_uptr_t handler;
3391 ret = get_user(handler, &act->sa_handler);
3392 new_ka.sa.sa_handler = compat_ptr(handler);
3393#ifdef __ARCH_HAS_SA_RESTORER
3394 ret |= get_user(restorer, &act->sa_restorer);
3395 new_ka.sa.sa_restorer = compat_ptr(restorer);
3396#endif
3397 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3398 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3399 if (ret)
3400 return -EFAULT;
3401 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3402 }
3403
3404 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3405 if (!ret && oact) {
3406 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3407 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3408 &oact->sa_handler);
3409 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3410 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3411#ifdef __ARCH_HAS_SA_RESTORER
3412 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3413 &oact->sa_restorer);
3414#endif
3415 }
3416 return ret;
3417}
3418#endif
3419#endif /* !CONFIG_ODD_RT_SIGACTION */
3420
3421#ifdef CONFIG_OLD_SIGACTION
3422SYSCALL_DEFINE3(sigaction, int, sig,
3423 const struct old_sigaction __user *, act,
3424 struct old_sigaction __user *, oact)
3425{
3426 struct k_sigaction new_ka, old_ka;
3427 int ret;
3428
3429 if (act) {
3430 old_sigset_t mask;
3431 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3432 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3433 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3434 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3435 __get_user(mask, &act->sa_mask))
3436 return -EFAULT;
3437#ifdef __ARCH_HAS_KA_RESTORER
3438 new_ka.ka_restorer = NULL;
3439#endif
3440 siginitset(&new_ka.sa.sa_mask, mask);
3441 }
3442
3443 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3444
3445 if (!ret && oact) {
3446 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3447 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3448 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3449 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3450 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3451 return -EFAULT;
3452 }
3453
3454 return ret;
3455}
3456#endif
3457#ifdef CONFIG_COMPAT_OLD_SIGACTION
3458COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3459 const struct compat_old_sigaction __user *, act,
3460 struct compat_old_sigaction __user *, oact)
3461{
3462 struct k_sigaction new_ka, old_ka;
3463 int ret;
3464 compat_old_sigset_t mask;
3465 compat_uptr_t handler, restorer;
3466
3467 if (act) {
3468 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3469 __get_user(handler, &act->sa_handler) ||
3470 __get_user(restorer, &act->sa_restorer) ||
3471 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3472 __get_user(mask, &act->sa_mask))
3473 return -EFAULT;
3474
3475#ifdef __ARCH_HAS_KA_RESTORER
3476 new_ka.ka_restorer = NULL;
3477#endif
3478 new_ka.sa.sa_handler = compat_ptr(handler);
3479 new_ka.sa.sa_restorer = compat_ptr(restorer);
3480 siginitset(&new_ka.sa.sa_mask, mask);
3481 }
3482
3483 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3484
3485 if (!ret && oact) {
3486 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3487 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3488 &oact->sa_handler) ||
3489 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3490 &oact->sa_restorer) ||
3491 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3492 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3493 return -EFAULT;
3494 }
3495 return ret;
3496}
3497#endif
3498
3499#ifdef __ARCH_WANT_SYS_SGETMASK
3500
3501/*
3502 * For backwards compatibility. Functionality superseded by sigprocmask.
3503 */
3504SYSCALL_DEFINE0(sgetmask)
3505{
3506 /* SMP safe */
3507 return current->blocked.sig[0];
3508}
3509
3510SYSCALL_DEFINE1(ssetmask, int, newmask)
3511{
3512 int old = current->blocked.sig[0];
3513 sigset_t newset;
3514
3515 siginitset(&newset, newmask);
3516 set_current_blocked(&newset);
3517
3518 return old;
3519}
3520#endif /* __ARCH_WANT_SGETMASK */
3521
3522#ifdef __ARCH_WANT_SYS_SIGNAL
3523/*
3524 * For backwards compatibility. Functionality superseded by sigaction.
3525 */
3526SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3527{
3528 struct k_sigaction new_sa, old_sa;
3529 int ret;
3530
3531 new_sa.sa.sa_handler = handler;
3532 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3533 sigemptyset(&new_sa.sa.sa_mask);
3534
3535 ret = do_sigaction(sig, &new_sa, &old_sa);
3536
3537 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3538}
3539#endif /* __ARCH_WANT_SYS_SIGNAL */
3540
3541#ifdef __ARCH_WANT_SYS_PAUSE
3542
3543SYSCALL_DEFINE0(pause)
3544{
3545 while (!signal_pending(current)) {
3546 current->state = TASK_INTERRUPTIBLE;
3547 schedule();
3548 }
3549 return -ERESTARTNOHAND;
3550}
3551
3552#endif
3553
3554int sigsuspend(sigset_t *set)
3555{
3556 current->saved_sigmask = current->blocked;
3557 set_current_blocked(set);
3558
3559 current->state = TASK_INTERRUPTIBLE;
3560 schedule();
3561 set_restore_sigmask();
3562 return -ERESTARTNOHAND;
3563}
3564
3565/**
3566 * sys_rt_sigsuspend - replace the signal mask for a value with the
3567 * @unewset value until a signal is received
3568 * @unewset: new signal mask value
3569 * @sigsetsize: size of sigset_t type
3570 */
3571SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3572{
3573 sigset_t newset;
3574
3575 /* XXX: Don't preclude handling different sized sigset_t's. */
3576 if (sigsetsize != sizeof(sigset_t))
3577 return -EINVAL;
3578
3579 if (copy_from_user(&newset, unewset, sizeof(newset)))
3580 return -EFAULT;
3581 return sigsuspend(&newset);
3582}
3583
3584#ifdef CONFIG_COMPAT
3585COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3586{
3587#ifdef __BIG_ENDIAN
3588 sigset_t newset;
3589 compat_sigset_t newset32;
3590
3591 /* XXX: Don't preclude handling different sized sigset_t's. */
3592 if (sigsetsize != sizeof(sigset_t))
3593 return -EINVAL;
3594
3595 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3596 return -EFAULT;
3597 sigset_from_compat(&newset, &newset32);
3598 return sigsuspend(&newset);
3599#else
3600 /* on little-endian bitmaps don't care about granularity */
3601 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3602#endif
3603}
3604#endif
3605
3606#ifdef CONFIG_OLD_SIGSUSPEND
3607SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3608{
3609 sigset_t blocked;
3610 siginitset(&blocked, mask);
3611 return sigsuspend(&blocked);
3612}
3613#endif
3614#ifdef CONFIG_OLD_SIGSUSPEND3
3615SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3616{
3617 sigset_t blocked;
3618 siginitset(&blocked, mask);
3619 return sigsuspend(&blocked);
3620}
3621#endif
3622
3623__weak const char *arch_vma_name(struct vm_area_struct *vma)
3624{
3625 return NULL;
3626}
3627
3628void __init signals_init(void)
3629{
3630 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3631}
3632
3633#ifdef CONFIG_KGDB_KDB
3634#include <linux/kdb.h>
3635/*
3636 * kdb_send_sig_info - Allows kdb to send signals without exposing
3637 * signal internals. This function checks if the required locks are
3638 * available before calling the main signal code, to avoid kdb
3639 * deadlocks.
3640 */
3641void
3642kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3643{
3644 static struct task_struct *kdb_prev_t;
3645 int sig, new_t;
3646 if (!spin_trylock(&t->sighand->siglock)) {
3647 kdb_printf("Can't do kill command now.\n"
3648 "The sigmask lock is held somewhere else in "
3649 "kernel, try again later\n");
3650 return;
3651 }
3652 spin_unlock(&t->sighand->siglock);
3653 new_t = kdb_prev_t != t;
3654 kdb_prev_t = t;
3655 if (t->state != TASK_RUNNING && new_t) {
3656 kdb_printf("Process is not RUNNING, sending a signal from "
3657 "kdb risks deadlock\n"
3658 "on the run queue locks. "
3659 "The signal has _not_ been sent.\n"
3660 "Reissue the kill command if you want to risk "
3661 "the deadlock.\n");
3662 return;
3663 }
3664 sig = info->si_signo;
3665 if (send_sig_info(sig, info, t))
3666 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3667 sig, t->pid);
3668 else
3669 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3670}
3671#endif /* CONFIG_KGDB_KDB */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
12 */
13
14#include <linux/slab.h>
15#include <linux/export.h>
16#include <linux/init.h>
17#include <linux/sched/mm.h>
18#include <linux/sched/user.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/sched/cputime.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/mm.h>
26#include <linux/proc_fs.h>
27#include <linux/tty.h>
28#include <linux/binfmts.h>
29#include <linux/coredump.h>
30#include <linux/security.h>
31#include <linux/syscalls.h>
32#include <linux/ptrace.h>
33#include <linux/signal.h>
34#include <linux/signalfd.h>
35#include <linux/ratelimit.h>
36#include <linux/task_work.h>
37#include <linux/capability.h>
38#include <linux/freezer.h>
39#include <linux/pid_namespace.h>
40#include <linux/nsproxy.h>
41#include <linux/user_namespace.h>
42#include <linux/uprobes.h>
43#include <linux/compat.h>
44#include <linux/cn_proc.h>
45#include <linux/compiler.h>
46#include <linux/posix-timers.h>
47#include <linux/cgroup.h>
48#include <linux/audit.h>
49#include <linux/sysctl.h>
50
51#define CREATE_TRACE_POINTS
52#include <trace/events/signal.h>
53
54#include <asm/param.h>
55#include <linux/uaccess.h>
56#include <asm/unistd.h>
57#include <asm/siginfo.h>
58#include <asm/cacheflush.h>
59#include <asm/syscall.h> /* for syscall_get_* */
60
61/*
62 * SLAB caches for signal bits.
63 */
64
65static struct kmem_cache *sigqueue_cachep;
66
67int print_fatal_signals __read_mostly;
68
69static void __user *sig_handler(struct task_struct *t, int sig)
70{
71 return t->sighand->action[sig - 1].sa.sa_handler;
72}
73
74static inline bool sig_handler_ignored(void __user *handler, int sig)
75{
76 /* Is it explicitly or implicitly ignored? */
77 return handler == SIG_IGN ||
78 (handler == SIG_DFL && sig_kernel_ignore(sig));
79}
80
81static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
82{
83 void __user *handler;
84
85 handler = sig_handler(t, sig);
86
87 /* SIGKILL and SIGSTOP may not be sent to the global init */
88 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
89 return true;
90
91 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
92 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
93 return true;
94
95 /* Only allow kernel generated signals to this kthread */
96 if (unlikely((t->flags & PF_KTHREAD) &&
97 (handler == SIG_KTHREAD_KERNEL) && !force))
98 return true;
99
100 return sig_handler_ignored(handler, sig);
101}
102
103static bool sig_ignored(struct task_struct *t, int sig, bool force)
104{
105 /*
106 * Blocked signals are never ignored, since the
107 * signal handler may change by the time it is
108 * unblocked.
109 */
110 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
111 return false;
112
113 /*
114 * Tracers may want to know about even ignored signal unless it
115 * is SIGKILL which can't be reported anyway but can be ignored
116 * by SIGNAL_UNKILLABLE task.
117 */
118 if (t->ptrace && sig != SIGKILL)
119 return false;
120
121 return sig_task_ignored(t, sig, force);
122}
123
124/*
125 * Re-calculate pending state from the set of locally pending
126 * signals, globally pending signals, and blocked signals.
127 */
128static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
129{
130 unsigned long ready;
131 long i;
132
133 switch (_NSIG_WORDS) {
134 default:
135 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
136 ready |= signal->sig[i] &~ blocked->sig[i];
137 break;
138
139 case 4: ready = signal->sig[3] &~ blocked->sig[3];
140 ready |= signal->sig[2] &~ blocked->sig[2];
141 ready |= signal->sig[1] &~ blocked->sig[1];
142 ready |= signal->sig[0] &~ blocked->sig[0];
143 break;
144
145 case 2: ready = signal->sig[1] &~ blocked->sig[1];
146 ready |= signal->sig[0] &~ blocked->sig[0];
147 break;
148
149 case 1: ready = signal->sig[0] &~ blocked->sig[0];
150 }
151 return ready != 0;
152}
153
154#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
155
156static bool recalc_sigpending_tsk(struct task_struct *t)
157{
158 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
159 PENDING(&t->pending, &t->blocked) ||
160 PENDING(&t->signal->shared_pending, &t->blocked) ||
161 cgroup_task_frozen(t)) {
162 set_tsk_thread_flag(t, TIF_SIGPENDING);
163 return true;
164 }
165
166 /*
167 * We must never clear the flag in another thread, or in current
168 * when it's possible the current syscall is returning -ERESTART*.
169 * So we don't clear it here, and only callers who know they should do.
170 */
171 return false;
172}
173
174void recalc_sigpending(void)
175{
176 if (!recalc_sigpending_tsk(current) && !freezing(current))
177 clear_thread_flag(TIF_SIGPENDING);
178
179}
180EXPORT_SYMBOL(recalc_sigpending);
181
182void calculate_sigpending(void)
183{
184 /* Have any signals or users of TIF_SIGPENDING been delayed
185 * until after fork?
186 */
187 spin_lock_irq(¤t->sighand->siglock);
188 set_tsk_thread_flag(current, TIF_SIGPENDING);
189 recalc_sigpending();
190 spin_unlock_irq(¤t->sighand->siglock);
191}
192
193/* Given the mask, find the first available signal that should be serviced. */
194
195#define SYNCHRONOUS_MASK \
196 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
197 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
198
199int next_signal(struct sigpending *pending, sigset_t *mask)
200{
201 unsigned long i, *s, *m, x;
202 int sig = 0;
203
204 s = pending->signal.sig;
205 m = mask->sig;
206
207 /*
208 * Handle the first word specially: it contains the
209 * synchronous signals that need to be dequeued first.
210 */
211 x = *s &~ *m;
212 if (x) {
213 if (x & SYNCHRONOUS_MASK)
214 x &= SYNCHRONOUS_MASK;
215 sig = ffz(~x) + 1;
216 return sig;
217 }
218
219 switch (_NSIG_WORDS) {
220 default:
221 for (i = 1; i < _NSIG_WORDS; ++i) {
222 x = *++s &~ *++m;
223 if (!x)
224 continue;
225 sig = ffz(~x) + i*_NSIG_BPW + 1;
226 break;
227 }
228 break;
229
230 case 2:
231 x = s[1] &~ m[1];
232 if (!x)
233 break;
234 sig = ffz(~x) + _NSIG_BPW + 1;
235 break;
236
237 case 1:
238 /* Nothing to do */
239 break;
240 }
241
242 return sig;
243}
244
245static inline void print_dropped_signal(int sig)
246{
247 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
248
249 if (!print_fatal_signals)
250 return;
251
252 if (!__ratelimit(&ratelimit_state))
253 return;
254
255 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
256 current->comm, current->pid, sig);
257}
258
259/**
260 * task_set_jobctl_pending - set jobctl pending bits
261 * @task: target task
262 * @mask: pending bits to set
263 *
264 * Clear @mask from @task->jobctl. @mask must be subset of
265 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
266 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
267 * cleared. If @task is already being killed or exiting, this function
268 * becomes noop.
269 *
270 * CONTEXT:
271 * Must be called with @task->sighand->siglock held.
272 *
273 * RETURNS:
274 * %true if @mask is set, %false if made noop because @task was dying.
275 */
276bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
277{
278 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
279 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
280 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
281
282 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
283 return false;
284
285 if (mask & JOBCTL_STOP_SIGMASK)
286 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
287
288 task->jobctl |= mask;
289 return true;
290}
291
292/**
293 * task_clear_jobctl_trapping - clear jobctl trapping bit
294 * @task: target task
295 *
296 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
297 * Clear it and wake up the ptracer. Note that we don't need any further
298 * locking. @task->siglock guarantees that @task->parent points to the
299 * ptracer.
300 *
301 * CONTEXT:
302 * Must be called with @task->sighand->siglock held.
303 */
304void task_clear_jobctl_trapping(struct task_struct *task)
305{
306 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
307 task->jobctl &= ~JOBCTL_TRAPPING;
308 smp_mb(); /* advised by wake_up_bit() */
309 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
310 }
311}
312
313/**
314 * task_clear_jobctl_pending - clear jobctl pending bits
315 * @task: target task
316 * @mask: pending bits to clear
317 *
318 * Clear @mask from @task->jobctl. @mask must be subset of
319 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
320 * STOP bits are cleared together.
321 *
322 * If clearing of @mask leaves no stop or trap pending, this function calls
323 * task_clear_jobctl_trapping().
324 *
325 * CONTEXT:
326 * Must be called with @task->sighand->siglock held.
327 */
328void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
329{
330 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
331
332 if (mask & JOBCTL_STOP_PENDING)
333 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
334
335 task->jobctl &= ~mask;
336
337 if (!(task->jobctl & JOBCTL_PENDING_MASK))
338 task_clear_jobctl_trapping(task);
339}
340
341/**
342 * task_participate_group_stop - participate in a group stop
343 * @task: task participating in a group stop
344 *
345 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
346 * Group stop states are cleared and the group stop count is consumed if
347 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
348 * stop, the appropriate `SIGNAL_*` flags are set.
349 *
350 * CONTEXT:
351 * Must be called with @task->sighand->siglock held.
352 *
353 * RETURNS:
354 * %true if group stop completion should be notified to the parent, %false
355 * otherwise.
356 */
357static bool task_participate_group_stop(struct task_struct *task)
358{
359 struct signal_struct *sig = task->signal;
360 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
361
362 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
363
364 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
365
366 if (!consume)
367 return false;
368
369 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
370 sig->group_stop_count--;
371
372 /*
373 * Tell the caller to notify completion iff we are entering into a
374 * fresh group stop. Read comment in do_signal_stop() for details.
375 */
376 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
377 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
378 return true;
379 }
380 return false;
381}
382
383void task_join_group_stop(struct task_struct *task)
384{
385 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
386 struct signal_struct *sig = current->signal;
387
388 if (sig->group_stop_count) {
389 sig->group_stop_count++;
390 mask |= JOBCTL_STOP_CONSUME;
391 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
392 return;
393
394 /* Have the new thread join an on-going signal group stop */
395 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
396}
397
398/*
399 * allocate a new signal queue record
400 * - this may be called without locks if and only if t == current, otherwise an
401 * appropriate lock must be held to stop the target task from exiting
402 */
403static struct sigqueue *
404__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
405 int override_rlimit, const unsigned int sigqueue_flags)
406{
407 struct sigqueue *q = NULL;
408 struct ucounts *ucounts;
409 long sigpending;
410
411 /*
412 * Protect access to @t credentials. This can go away when all
413 * callers hold rcu read lock.
414 *
415 * NOTE! A pending signal will hold on to the user refcount,
416 * and we get/put the refcount only when the sigpending count
417 * changes from/to zero.
418 */
419 rcu_read_lock();
420 ucounts = task_ucounts(t);
421 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
422 rcu_read_unlock();
423 if (!sigpending)
424 return NULL;
425
426 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
427 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
428 } else {
429 print_dropped_signal(sig);
430 }
431
432 if (unlikely(q == NULL)) {
433 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
434 } else {
435 INIT_LIST_HEAD(&q->list);
436 q->flags = sigqueue_flags;
437 q->ucounts = ucounts;
438 }
439 return q;
440}
441
442static void __sigqueue_free(struct sigqueue *q)
443{
444 if (q->flags & SIGQUEUE_PREALLOC)
445 return;
446 if (q->ucounts) {
447 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
448 q->ucounts = NULL;
449 }
450 kmem_cache_free(sigqueue_cachep, q);
451}
452
453void flush_sigqueue(struct sigpending *queue)
454{
455 struct sigqueue *q;
456
457 sigemptyset(&queue->signal);
458 while (!list_empty(&queue->list)) {
459 q = list_entry(queue->list.next, struct sigqueue , list);
460 list_del_init(&q->list);
461 __sigqueue_free(q);
462 }
463}
464
465/*
466 * Flush all pending signals for this kthread.
467 */
468void flush_signals(struct task_struct *t)
469{
470 unsigned long flags;
471
472 spin_lock_irqsave(&t->sighand->siglock, flags);
473 clear_tsk_thread_flag(t, TIF_SIGPENDING);
474 flush_sigqueue(&t->pending);
475 flush_sigqueue(&t->signal->shared_pending);
476 spin_unlock_irqrestore(&t->sighand->siglock, flags);
477}
478EXPORT_SYMBOL(flush_signals);
479
480#ifdef CONFIG_POSIX_TIMERS
481static void __flush_itimer_signals(struct sigpending *pending)
482{
483 sigset_t signal, retain;
484 struct sigqueue *q, *n;
485
486 signal = pending->signal;
487 sigemptyset(&retain);
488
489 list_for_each_entry_safe(q, n, &pending->list, list) {
490 int sig = q->info.si_signo;
491
492 if (likely(q->info.si_code != SI_TIMER)) {
493 sigaddset(&retain, sig);
494 } else {
495 sigdelset(&signal, sig);
496 list_del_init(&q->list);
497 __sigqueue_free(q);
498 }
499 }
500
501 sigorsets(&pending->signal, &signal, &retain);
502}
503
504void flush_itimer_signals(void)
505{
506 struct task_struct *tsk = current;
507 unsigned long flags;
508
509 spin_lock_irqsave(&tsk->sighand->siglock, flags);
510 __flush_itimer_signals(&tsk->pending);
511 __flush_itimer_signals(&tsk->signal->shared_pending);
512 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
513}
514#endif
515
516void ignore_signals(struct task_struct *t)
517{
518 int i;
519
520 for (i = 0; i < _NSIG; ++i)
521 t->sighand->action[i].sa.sa_handler = SIG_IGN;
522
523 flush_signals(t);
524}
525
526/*
527 * Flush all handlers for a task.
528 */
529
530void
531flush_signal_handlers(struct task_struct *t, int force_default)
532{
533 int i;
534 struct k_sigaction *ka = &t->sighand->action[0];
535 for (i = _NSIG ; i != 0 ; i--) {
536 if (force_default || ka->sa.sa_handler != SIG_IGN)
537 ka->sa.sa_handler = SIG_DFL;
538 ka->sa.sa_flags = 0;
539#ifdef __ARCH_HAS_SA_RESTORER
540 ka->sa.sa_restorer = NULL;
541#endif
542 sigemptyset(&ka->sa.sa_mask);
543 ka++;
544 }
545}
546
547bool unhandled_signal(struct task_struct *tsk, int sig)
548{
549 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
550 if (is_global_init(tsk))
551 return true;
552
553 if (handler != SIG_IGN && handler != SIG_DFL)
554 return false;
555
556 /* If dying, we handle all new signals by ignoring them */
557 if (fatal_signal_pending(tsk))
558 return false;
559
560 /* if ptraced, let the tracer determine */
561 return !tsk->ptrace;
562}
563
564static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
565 bool *resched_timer)
566{
567 struct sigqueue *q, *first = NULL;
568
569 /*
570 * Collect the siginfo appropriate to this signal. Check if
571 * there is another siginfo for the same signal.
572 */
573 list_for_each_entry(q, &list->list, list) {
574 if (q->info.si_signo == sig) {
575 if (first)
576 goto still_pending;
577 first = q;
578 }
579 }
580
581 sigdelset(&list->signal, sig);
582
583 if (first) {
584still_pending:
585 list_del_init(&first->list);
586 copy_siginfo(info, &first->info);
587
588 *resched_timer =
589 (first->flags & SIGQUEUE_PREALLOC) &&
590 (info->si_code == SI_TIMER) &&
591 (info->si_sys_private);
592
593 __sigqueue_free(first);
594 } else {
595 /*
596 * Ok, it wasn't in the queue. This must be
597 * a fast-pathed signal or we must have been
598 * out of queue space. So zero out the info.
599 */
600 clear_siginfo(info);
601 info->si_signo = sig;
602 info->si_errno = 0;
603 info->si_code = SI_USER;
604 info->si_pid = 0;
605 info->si_uid = 0;
606 }
607}
608
609static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
610 kernel_siginfo_t *info, bool *resched_timer)
611{
612 int sig = next_signal(pending, mask);
613
614 if (sig)
615 collect_signal(sig, pending, info, resched_timer);
616 return sig;
617}
618
619/*
620 * Dequeue a signal and return the element to the caller, which is
621 * expected to free it.
622 *
623 * All callers have to hold the siglock.
624 */
625int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
626 kernel_siginfo_t *info, enum pid_type *type)
627{
628 bool resched_timer = false;
629 int signr;
630
631 /* We only dequeue private signals from ourselves, we don't let
632 * signalfd steal them
633 */
634 *type = PIDTYPE_PID;
635 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
636 if (!signr) {
637 *type = PIDTYPE_TGID;
638 signr = __dequeue_signal(&tsk->signal->shared_pending,
639 mask, info, &resched_timer);
640#ifdef CONFIG_POSIX_TIMERS
641 /*
642 * itimer signal ?
643 *
644 * itimers are process shared and we restart periodic
645 * itimers in the signal delivery path to prevent DoS
646 * attacks in the high resolution timer case. This is
647 * compliant with the old way of self-restarting
648 * itimers, as the SIGALRM is a legacy signal and only
649 * queued once. Changing the restart behaviour to
650 * restart the timer in the signal dequeue path is
651 * reducing the timer noise on heavy loaded !highres
652 * systems too.
653 */
654 if (unlikely(signr == SIGALRM)) {
655 struct hrtimer *tmr = &tsk->signal->real_timer;
656
657 if (!hrtimer_is_queued(tmr) &&
658 tsk->signal->it_real_incr != 0) {
659 hrtimer_forward(tmr, tmr->base->get_time(),
660 tsk->signal->it_real_incr);
661 hrtimer_restart(tmr);
662 }
663 }
664#endif
665 }
666
667 recalc_sigpending();
668 if (!signr)
669 return 0;
670
671 if (unlikely(sig_kernel_stop(signr))) {
672 /*
673 * Set a marker that we have dequeued a stop signal. Our
674 * caller might release the siglock and then the pending
675 * stop signal it is about to process is no longer in the
676 * pending bitmasks, but must still be cleared by a SIGCONT
677 * (and overruled by a SIGKILL). So those cases clear this
678 * shared flag after we've set it. Note that this flag may
679 * remain set after the signal we return is ignored or
680 * handled. That doesn't matter because its only purpose
681 * is to alert stop-signal processing code when another
682 * processor has come along and cleared the flag.
683 */
684 current->jobctl |= JOBCTL_STOP_DEQUEUED;
685 }
686#ifdef CONFIG_POSIX_TIMERS
687 if (resched_timer) {
688 /*
689 * Release the siglock to ensure proper locking order
690 * of timer locks outside of siglocks. Note, we leave
691 * irqs disabled here, since the posix-timers code is
692 * about to disable them again anyway.
693 */
694 spin_unlock(&tsk->sighand->siglock);
695 posixtimer_rearm(info);
696 spin_lock(&tsk->sighand->siglock);
697
698 /* Don't expose the si_sys_private value to userspace */
699 info->si_sys_private = 0;
700 }
701#endif
702 return signr;
703}
704EXPORT_SYMBOL_GPL(dequeue_signal);
705
706static int dequeue_synchronous_signal(kernel_siginfo_t *info)
707{
708 struct task_struct *tsk = current;
709 struct sigpending *pending = &tsk->pending;
710 struct sigqueue *q, *sync = NULL;
711
712 /*
713 * Might a synchronous signal be in the queue?
714 */
715 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
716 return 0;
717
718 /*
719 * Return the first synchronous signal in the queue.
720 */
721 list_for_each_entry(q, &pending->list, list) {
722 /* Synchronous signals have a positive si_code */
723 if ((q->info.si_code > SI_USER) &&
724 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
725 sync = q;
726 goto next;
727 }
728 }
729 return 0;
730next:
731 /*
732 * Check if there is another siginfo for the same signal.
733 */
734 list_for_each_entry_continue(q, &pending->list, list) {
735 if (q->info.si_signo == sync->info.si_signo)
736 goto still_pending;
737 }
738
739 sigdelset(&pending->signal, sync->info.si_signo);
740 recalc_sigpending();
741still_pending:
742 list_del_init(&sync->list);
743 copy_siginfo(info, &sync->info);
744 __sigqueue_free(sync);
745 return info->si_signo;
746}
747
748/*
749 * Tell a process that it has a new active signal..
750 *
751 * NOTE! we rely on the previous spin_lock to
752 * lock interrupts for us! We can only be called with
753 * "siglock" held, and the local interrupt must
754 * have been disabled when that got acquired!
755 *
756 * No need to set need_resched since signal event passing
757 * goes through ->blocked
758 */
759void signal_wake_up_state(struct task_struct *t, unsigned int state)
760{
761 lockdep_assert_held(&t->sighand->siglock);
762
763 set_tsk_thread_flag(t, TIF_SIGPENDING);
764
765 /*
766 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
767 * case. We don't check t->state here because there is a race with it
768 * executing another processor and just now entering stopped state.
769 * By using wake_up_state, we ensure the process will wake up and
770 * handle its death signal.
771 */
772 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
773 kick_process(t);
774}
775
776/*
777 * Remove signals in mask from the pending set and queue.
778 * Returns 1 if any signals were found.
779 *
780 * All callers must be holding the siglock.
781 */
782static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
783{
784 struct sigqueue *q, *n;
785 sigset_t m;
786
787 sigandsets(&m, mask, &s->signal);
788 if (sigisemptyset(&m))
789 return;
790
791 sigandnsets(&s->signal, &s->signal, mask);
792 list_for_each_entry_safe(q, n, &s->list, list) {
793 if (sigismember(mask, q->info.si_signo)) {
794 list_del_init(&q->list);
795 __sigqueue_free(q);
796 }
797 }
798}
799
800static inline int is_si_special(const struct kernel_siginfo *info)
801{
802 return info <= SEND_SIG_PRIV;
803}
804
805static inline bool si_fromuser(const struct kernel_siginfo *info)
806{
807 return info == SEND_SIG_NOINFO ||
808 (!is_si_special(info) && SI_FROMUSER(info));
809}
810
811/*
812 * called with RCU read lock from check_kill_permission()
813 */
814static bool kill_ok_by_cred(struct task_struct *t)
815{
816 const struct cred *cred = current_cred();
817 const struct cred *tcred = __task_cred(t);
818
819 return uid_eq(cred->euid, tcred->suid) ||
820 uid_eq(cred->euid, tcred->uid) ||
821 uid_eq(cred->uid, tcred->suid) ||
822 uid_eq(cred->uid, tcred->uid) ||
823 ns_capable(tcred->user_ns, CAP_KILL);
824}
825
826/*
827 * Bad permissions for sending the signal
828 * - the caller must hold the RCU read lock
829 */
830static int check_kill_permission(int sig, struct kernel_siginfo *info,
831 struct task_struct *t)
832{
833 struct pid *sid;
834 int error;
835
836 if (!valid_signal(sig))
837 return -EINVAL;
838
839 if (!si_fromuser(info))
840 return 0;
841
842 error = audit_signal_info(sig, t); /* Let audit system see the signal */
843 if (error)
844 return error;
845
846 if (!same_thread_group(current, t) &&
847 !kill_ok_by_cred(t)) {
848 switch (sig) {
849 case SIGCONT:
850 sid = task_session(t);
851 /*
852 * We don't return the error if sid == NULL. The
853 * task was unhashed, the caller must notice this.
854 */
855 if (!sid || sid == task_session(current))
856 break;
857 fallthrough;
858 default:
859 return -EPERM;
860 }
861 }
862
863 return security_task_kill(t, info, sig, NULL);
864}
865
866/**
867 * ptrace_trap_notify - schedule trap to notify ptracer
868 * @t: tracee wanting to notify tracer
869 *
870 * This function schedules sticky ptrace trap which is cleared on the next
871 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
872 * ptracer.
873 *
874 * If @t is running, STOP trap will be taken. If trapped for STOP and
875 * ptracer is listening for events, tracee is woken up so that it can
876 * re-trap for the new event. If trapped otherwise, STOP trap will be
877 * eventually taken without returning to userland after the existing traps
878 * are finished by PTRACE_CONT.
879 *
880 * CONTEXT:
881 * Must be called with @task->sighand->siglock held.
882 */
883static void ptrace_trap_notify(struct task_struct *t)
884{
885 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
886 lockdep_assert_held(&t->sighand->siglock);
887
888 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
889 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
890}
891
892/*
893 * Handle magic process-wide effects of stop/continue signals. Unlike
894 * the signal actions, these happen immediately at signal-generation
895 * time regardless of blocking, ignoring, or handling. This does the
896 * actual continuing for SIGCONT, but not the actual stopping for stop
897 * signals. The process stop is done as a signal action for SIG_DFL.
898 *
899 * Returns true if the signal should be actually delivered, otherwise
900 * it should be dropped.
901 */
902static bool prepare_signal(int sig, struct task_struct *p, bool force)
903{
904 struct signal_struct *signal = p->signal;
905 struct task_struct *t;
906 sigset_t flush;
907
908 if (signal->flags & SIGNAL_GROUP_EXIT) {
909 if (signal->core_state)
910 return sig == SIGKILL;
911 /*
912 * The process is in the middle of dying, drop the signal.
913 */
914 return false;
915 } else if (sig_kernel_stop(sig)) {
916 /*
917 * This is a stop signal. Remove SIGCONT from all queues.
918 */
919 siginitset(&flush, sigmask(SIGCONT));
920 flush_sigqueue_mask(&flush, &signal->shared_pending);
921 for_each_thread(p, t)
922 flush_sigqueue_mask(&flush, &t->pending);
923 } else if (sig == SIGCONT) {
924 unsigned int why;
925 /*
926 * Remove all stop signals from all queues, wake all threads.
927 */
928 siginitset(&flush, SIG_KERNEL_STOP_MASK);
929 flush_sigqueue_mask(&flush, &signal->shared_pending);
930 for_each_thread(p, t) {
931 flush_sigqueue_mask(&flush, &t->pending);
932 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
933 if (likely(!(t->ptrace & PT_SEIZED))) {
934 t->jobctl &= ~JOBCTL_STOPPED;
935 wake_up_state(t, __TASK_STOPPED);
936 } else
937 ptrace_trap_notify(t);
938 }
939
940 /*
941 * Notify the parent with CLD_CONTINUED if we were stopped.
942 *
943 * If we were in the middle of a group stop, we pretend it
944 * was already finished, and then continued. Since SIGCHLD
945 * doesn't queue we report only CLD_STOPPED, as if the next
946 * CLD_CONTINUED was dropped.
947 */
948 why = 0;
949 if (signal->flags & SIGNAL_STOP_STOPPED)
950 why |= SIGNAL_CLD_CONTINUED;
951 else if (signal->group_stop_count)
952 why |= SIGNAL_CLD_STOPPED;
953
954 if (why) {
955 /*
956 * The first thread which returns from do_signal_stop()
957 * will take ->siglock, notice SIGNAL_CLD_MASK, and
958 * notify its parent. See get_signal().
959 */
960 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
961 signal->group_stop_count = 0;
962 signal->group_exit_code = 0;
963 }
964 }
965
966 return !sig_ignored(p, sig, force);
967}
968
969/*
970 * Test if P wants to take SIG. After we've checked all threads with this,
971 * it's equivalent to finding no threads not blocking SIG. Any threads not
972 * blocking SIG were ruled out because they are not running and already
973 * have pending signals. Such threads will dequeue from the shared queue
974 * as soon as they're available, so putting the signal on the shared queue
975 * will be equivalent to sending it to one such thread.
976 */
977static inline bool wants_signal(int sig, struct task_struct *p)
978{
979 if (sigismember(&p->blocked, sig))
980 return false;
981
982 if (p->flags & PF_EXITING)
983 return false;
984
985 if (sig == SIGKILL)
986 return true;
987
988 if (task_is_stopped_or_traced(p))
989 return false;
990
991 return task_curr(p) || !task_sigpending(p);
992}
993
994static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
995{
996 struct signal_struct *signal = p->signal;
997 struct task_struct *t;
998
999 /*
1000 * Now find a thread we can wake up to take the signal off the queue.
1001 *
1002 * Try the suggested task first (may or may not be the main thread).
1003 */
1004 if (wants_signal(sig, p))
1005 t = p;
1006 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1007 /*
1008 * There is just one thread and it does not need to be woken.
1009 * It will dequeue unblocked signals before it runs again.
1010 */
1011 return;
1012 else {
1013 /*
1014 * Otherwise try to find a suitable thread.
1015 */
1016 t = signal->curr_target;
1017 while (!wants_signal(sig, t)) {
1018 t = next_thread(t);
1019 if (t == signal->curr_target)
1020 /*
1021 * No thread needs to be woken.
1022 * Any eligible threads will see
1023 * the signal in the queue soon.
1024 */
1025 return;
1026 }
1027 signal->curr_target = t;
1028 }
1029
1030 /*
1031 * Found a killable thread. If the signal will be fatal,
1032 * then start taking the whole group down immediately.
1033 */
1034 if (sig_fatal(p, sig) &&
1035 (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1036 !sigismember(&t->real_blocked, sig) &&
1037 (sig == SIGKILL || !p->ptrace)) {
1038 /*
1039 * This signal will be fatal to the whole group.
1040 */
1041 if (!sig_kernel_coredump(sig)) {
1042 /*
1043 * Start a group exit and wake everybody up.
1044 * This way we don't have other threads
1045 * running and doing things after a slower
1046 * thread has the fatal signal pending.
1047 */
1048 signal->flags = SIGNAL_GROUP_EXIT;
1049 signal->group_exit_code = sig;
1050 signal->group_stop_count = 0;
1051 __for_each_thread(signal, t) {
1052 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1053 sigaddset(&t->pending.signal, SIGKILL);
1054 signal_wake_up(t, 1);
1055 }
1056 return;
1057 }
1058 }
1059
1060 /*
1061 * The signal is already in the shared-pending queue.
1062 * Tell the chosen thread to wake up and dequeue it.
1063 */
1064 signal_wake_up(t, sig == SIGKILL);
1065 return;
1066}
1067
1068static inline bool legacy_queue(struct sigpending *signals, int sig)
1069{
1070 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1071}
1072
1073static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1074 struct task_struct *t, enum pid_type type, bool force)
1075{
1076 struct sigpending *pending;
1077 struct sigqueue *q;
1078 int override_rlimit;
1079 int ret = 0, result;
1080
1081 lockdep_assert_held(&t->sighand->siglock);
1082
1083 result = TRACE_SIGNAL_IGNORED;
1084 if (!prepare_signal(sig, t, force))
1085 goto ret;
1086
1087 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1088 /*
1089 * Short-circuit ignored signals and support queuing
1090 * exactly one non-rt signal, so that we can get more
1091 * detailed information about the cause of the signal.
1092 */
1093 result = TRACE_SIGNAL_ALREADY_PENDING;
1094 if (legacy_queue(pending, sig))
1095 goto ret;
1096
1097 result = TRACE_SIGNAL_DELIVERED;
1098 /*
1099 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1100 */
1101 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1102 goto out_set;
1103
1104 /*
1105 * Real-time signals must be queued if sent by sigqueue, or
1106 * some other real-time mechanism. It is implementation
1107 * defined whether kill() does so. We attempt to do so, on
1108 * the principle of least surprise, but since kill is not
1109 * allowed to fail with EAGAIN when low on memory we just
1110 * make sure at least one signal gets delivered and don't
1111 * pass on the info struct.
1112 */
1113 if (sig < SIGRTMIN)
1114 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1115 else
1116 override_rlimit = 0;
1117
1118 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1119
1120 if (q) {
1121 list_add_tail(&q->list, &pending->list);
1122 switch ((unsigned long) info) {
1123 case (unsigned long) SEND_SIG_NOINFO:
1124 clear_siginfo(&q->info);
1125 q->info.si_signo = sig;
1126 q->info.si_errno = 0;
1127 q->info.si_code = SI_USER;
1128 q->info.si_pid = task_tgid_nr_ns(current,
1129 task_active_pid_ns(t));
1130 rcu_read_lock();
1131 q->info.si_uid =
1132 from_kuid_munged(task_cred_xxx(t, user_ns),
1133 current_uid());
1134 rcu_read_unlock();
1135 break;
1136 case (unsigned long) SEND_SIG_PRIV:
1137 clear_siginfo(&q->info);
1138 q->info.si_signo = sig;
1139 q->info.si_errno = 0;
1140 q->info.si_code = SI_KERNEL;
1141 q->info.si_pid = 0;
1142 q->info.si_uid = 0;
1143 break;
1144 default:
1145 copy_siginfo(&q->info, info);
1146 break;
1147 }
1148 } else if (!is_si_special(info) &&
1149 sig >= SIGRTMIN && info->si_code != SI_USER) {
1150 /*
1151 * Queue overflow, abort. We may abort if the
1152 * signal was rt and sent by user using something
1153 * other than kill().
1154 */
1155 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1156 ret = -EAGAIN;
1157 goto ret;
1158 } else {
1159 /*
1160 * This is a silent loss of information. We still
1161 * send the signal, but the *info bits are lost.
1162 */
1163 result = TRACE_SIGNAL_LOSE_INFO;
1164 }
1165
1166out_set:
1167 signalfd_notify(t, sig);
1168 sigaddset(&pending->signal, sig);
1169
1170 /* Let multiprocess signals appear after on-going forks */
1171 if (type > PIDTYPE_TGID) {
1172 struct multiprocess_signals *delayed;
1173 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1174 sigset_t *signal = &delayed->signal;
1175 /* Can't queue both a stop and a continue signal */
1176 if (sig == SIGCONT)
1177 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1178 else if (sig_kernel_stop(sig))
1179 sigdelset(signal, SIGCONT);
1180 sigaddset(signal, sig);
1181 }
1182 }
1183
1184 complete_signal(sig, t, type);
1185ret:
1186 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1187 return ret;
1188}
1189
1190static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1191{
1192 bool ret = false;
1193 switch (siginfo_layout(info->si_signo, info->si_code)) {
1194 case SIL_KILL:
1195 case SIL_CHLD:
1196 case SIL_RT:
1197 ret = true;
1198 break;
1199 case SIL_TIMER:
1200 case SIL_POLL:
1201 case SIL_FAULT:
1202 case SIL_FAULT_TRAPNO:
1203 case SIL_FAULT_MCEERR:
1204 case SIL_FAULT_BNDERR:
1205 case SIL_FAULT_PKUERR:
1206 case SIL_FAULT_PERF_EVENT:
1207 case SIL_SYS:
1208 ret = false;
1209 break;
1210 }
1211 return ret;
1212}
1213
1214int send_signal_locked(int sig, struct kernel_siginfo *info,
1215 struct task_struct *t, enum pid_type type)
1216{
1217 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1218 bool force = false;
1219
1220 if (info == SEND_SIG_NOINFO) {
1221 /* Force if sent from an ancestor pid namespace */
1222 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1223 } else if (info == SEND_SIG_PRIV) {
1224 /* Don't ignore kernel generated signals */
1225 force = true;
1226 } else if (has_si_pid_and_uid(info)) {
1227 /* SIGKILL and SIGSTOP is special or has ids */
1228 struct user_namespace *t_user_ns;
1229
1230 rcu_read_lock();
1231 t_user_ns = task_cred_xxx(t, user_ns);
1232 if (current_user_ns() != t_user_ns) {
1233 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1234 info->si_uid = from_kuid_munged(t_user_ns, uid);
1235 }
1236 rcu_read_unlock();
1237
1238 /* A kernel generated signal? */
1239 force = (info->si_code == SI_KERNEL);
1240
1241 /* From an ancestor pid namespace? */
1242 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1243 info->si_pid = 0;
1244 force = true;
1245 }
1246 }
1247 return __send_signal_locked(sig, info, t, type, force);
1248}
1249
1250static void print_fatal_signal(int signr)
1251{
1252 struct pt_regs *regs = task_pt_regs(current);
1253 struct file *exe_file;
1254
1255 exe_file = get_task_exe_file(current);
1256 if (exe_file) {
1257 pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1258 exe_file, current->comm, signr);
1259 fput(exe_file);
1260 } else {
1261 pr_info("%s: potentially unexpected fatal signal %d.\n",
1262 current->comm, signr);
1263 }
1264
1265#if defined(__i386__) && !defined(__arch_um__)
1266 pr_info("code at %08lx: ", regs->ip);
1267 {
1268 int i;
1269 for (i = 0; i < 16; i++) {
1270 unsigned char insn;
1271
1272 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1273 break;
1274 pr_cont("%02x ", insn);
1275 }
1276 }
1277 pr_cont("\n");
1278#endif
1279 preempt_disable();
1280 show_regs(regs);
1281 preempt_enable();
1282}
1283
1284static int __init setup_print_fatal_signals(char *str)
1285{
1286 get_option (&str, &print_fatal_signals);
1287
1288 return 1;
1289}
1290
1291__setup("print-fatal-signals=", setup_print_fatal_signals);
1292
1293int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1294 enum pid_type type)
1295{
1296 unsigned long flags;
1297 int ret = -ESRCH;
1298
1299 if (lock_task_sighand(p, &flags)) {
1300 ret = send_signal_locked(sig, info, p, type);
1301 unlock_task_sighand(p, &flags);
1302 }
1303
1304 return ret;
1305}
1306
1307enum sig_handler {
1308 HANDLER_CURRENT, /* If reachable use the current handler */
1309 HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1310 HANDLER_EXIT, /* Only visible as the process exit code */
1311};
1312
1313/*
1314 * Force a signal that the process can't ignore: if necessary
1315 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1316 *
1317 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1318 * since we do not want to have a signal handler that was blocked
1319 * be invoked when user space had explicitly blocked it.
1320 *
1321 * We don't want to have recursive SIGSEGV's etc, for example,
1322 * that is why we also clear SIGNAL_UNKILLABLE.
1323 */
1324static int
1325force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1326 enum sig_handler handler)
1327{
1328 unsigned long int flags;
1329 int ret, blocked, ignored;
1330 struct k_sigaction *action;
1331 int sig = info->si_signo;
1332
1333 spin_lock_irqsave(&t->sighand->siglock, flags);
1334 action = &t->sighand->action[sig-1];
1335 ignored = action->sa.sa_handler == SIG_IGN;
1336 blocked = sigismember(&t->blocked, sig);
1337 if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1338 action->sa.sa_handler = SIG_DFL;
1339 if (handler == HANDLER_EXIT)
1340 action->sa.sa_flags |= SA_IMMUTABLE;
1341 if (blocked)
1342 sigdelset(&t->blocked, sig);
1343 }
1344 /*
1345 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1346 * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1347 */
1348 if (action->sa.sa_handler == SIG_DFL &&
1349 (!t->ptrace || (handler == HANDLER_EXIT)))
1350 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1351 ret = send_signal_locked(sig, info, t, PIDTYPE_PID);
1352 /* This can happen if the signal was already pending and blocked */
1353 if (!task_sigpending(t))
1354 signal_wake_up(t, 0);
1355 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1356
1357 return ret;
1358}
1359
1360int force_sig_info(struct kernel_siginfo *info)
1361{
1362 return force_sig_info_to_task(info, current, HANDLER_CURRENT);
1363}
1364
1365/*
1366 * Nuke all other threads in the group.
1367 */
1368int zap_other_threads(struct task_struct *p)
1369{
1370 struct task_struct *t;
1371 int count = 0;
1372
1373 p->signal->group_stop_count = 0;
1374
1375 for_other_threads(p, t) {
1376 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1377 /* Don't require de_thread to wait for the vhost_worker */
1378 if ((t->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)
1379 count++;
1380
1381 /* Don't bother with already dead threads */
1382 if (t->exit_state)
1383 continue;
1384 sigaddset(&t->pending.signal, SIGKILL);
1385 signal_wake_up(t, 1);
1386 }
1387
1388 return count;
1389}
1390
1391struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1392 unsigned long *flags)
1393{
1394 struct sighand_struct *sighand;
1395
1396 rcu_read_lock();
1397 for (;;) {
1398 sighand = rcu_dereference(tsk->sighand);
1399 if (unlikely(sighand == NULL))
1400 break;
1401
1402 /*
1403 * This sighand can be already freed and even reused, but
1404 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1405 * initializes ->siglock: this slab can't go away, it has
1406 * the same object type, ->siglock can't be reinitialized.
1407 *
1408 * We need to ensure that tsk->sighand is still the same
1409 * after we take the lock, we can race with de_thread() or
1410 * __exit_signal(). In the latter case the next iteration
1411 * must see ->sighand == NULL.
1412 */
1413 spin_lock_irqsave(&sighand->siglock, *flags);
1414 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1415 break;
1416 spin_unlock_irqrestore(&sighand->siglock, *flags);
1417 }
1418 rcu_read_unlock();
1419
1420 return sighand;
1421}
1422
1423#ifdef CONFIG_LOCKDEP
1424void lockdep_assert_task_sighand_held(struct task_struct *task)
1425{
1426 struct sighand_struct *sighand;
1427
1428 rcu_read_lock();
1429 sighand = rcu_dereference(task->sighand);
1430 if (sighand)
1431 lockdep_assert_held(&sighand->siglock);
1432 else
1433 WARN_ON_ONCE(1);
1434 rcu_read_unlock();
1435}
1436#endif
1437
1438/*
1439 * send signal info to all the members of a group
1440 */
1441int group_send_sig_info(int sig, struct kernel_siginfo *info,
1442 struct task_struct *p, enum pid_type type)
1443{
1444 int ret;
1445
1446 rcu_read_lock();
1447 ret = check_kill_permission(sig, info, p);
1448 rcu_read_unlock();
1449
1450 if (!ret && sig)
1451 ret = do_send_sig_info(sig, info, p, type);
1452
1453 return ret;
1454}
1455
1456/*
1457 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1458 * control characters do (^C, ^Z etc)
1459 * - the caller must hold at least a readlock on tasklist_lock
1460 */
1461int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1462{
1463 struct task_struct *p = NULL;
1464 int ret = -ESRCH;
1465
1466 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1467 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1468 /*
1469 * If group_send_sig_info() succeeds at least once ret
1470 * becomes 0 and after that the code below has no effect.
1471 * Otherwise we return the last err or -ESRCH if this
1472 * process group is empty.
1473 */
1474 if (ret)
1475 ret = err;
1476 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1477
1478 return ret;
1479}
1480
1481int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1482{
1483 int error = -ESRCH;
1484 struct task_struct *p;
1485
1486 for (;;) {
1487 rcu_read_lock();
1488 p = pid_task(pid, PIDTYPE_PID);
1489 if (p)
1490 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1491 rcu_read_unlock();
1492 if (likely(!p || error != -ESRCH))
1493 return error;
1494
1495 /*
1496 * The task was unhashed in between, try again. If it
1497 * is dead, pid_task() will return NULL, if we race with
1498 * de_thread() it will find the new leader.
1499 */
1500 }
1501}
1502
1503static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1504{
1505 int error;
1506 rcu_read_lock();
1507 error = kill_pid_info(sig, info, find_vpid(pid));
1508 rcu_read_unlock();
1509 return error;
1510}
1511
1512static inline bool kill_as_cred_perm(const struct cred *cred,
1513 struct task_struct *target)
1514{
1515 const struct cred *pcred = __task_cred(target);
1516
1517 return uid_eq(cred->euid, pcred->suid) ||
1518 uid_eq(cred->euid, pcred->uid) ||
1519 uid_eq(cred->uid, pcred->suid) ||
1520 uid_eq(cred->uid, pcred->uid);
1521}
1522
1523/*
1524 * The usb asyncio usage of siginfo is wrong. The glibc support
1525 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1526 * AKA after the generic fields:
1527 * kernel_pid_t si_pid;
1528 * kernel_uid32_t si_uid;
1529 * sigval_t si_value;
1530 *
1531 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1532 * after the generic fields is:
1533 * void __user *si_addr;
1534 *
1535 * This is a practical problem when there is a 64bit big endian kernel
1536 * and a 32bit userspace. As the 32bit address will encoded in the low
1537 * 32bits of the pointer. Those low 32bits will be stored at higher
1538 * address than appear in a 32 bit pointer. So userspace will not
1539 * see the address it was expecting for it's completions.
1540 *
1541 * There is nothing in the encoding that can allow
1542 * copy_siginfo_to_user32 to detect this confusion of formats, so
1543 * handle this by requiring the caller of kill_pid_usb_asyncio to
1544 * notice when this situration takes place and to store the 32bit
1545 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1546 * parameter.
1547 */
1548int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1549 struct pid *pid, const struct cred *cred)
1550{
1551 struct kernel_siginfo info;
1552 struct task_struct *p;
1553 unsigned long flags;
1554 int ret = -EINVAL;
1555
1556 if (!valid_signal(sig))
1557 return ret;
1558
1559 clear_siginfo(&info);
1560 info.si_signo = sig;
1561 info.si_errno = errno;
1562 info.si_code = SI_ASYNCIO;
1563 *((sigval_t *)&info.si_pid) = addr;
1564
1565 rcu_read_lock();
1566 p = pid_task(pid, PIDTYPE_PID);
1567 if (!p) {
1568 ret = -ESRCH;
1569 goto out_unlock;
1570 }
1571 if (!kill_as_cred_perm(cred, p)) {
1572 ret = -EPERM;
1573 goto out_unlock;
1574 }
1575 ret = security_task_kill(p, &info, sig, cred);
1576 if (ret)
1577 goto out_unlock;
1578
1579 if (sig) {
1580 if (lock_task_sighand(p, &flags)) {
1581 ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false);
1582 unlock_task_sighand(p, &flags);
1583 } else
1584 ret = -ESRCH;
1585 }
1586out_unlock:
1587 rcu_read_unlock();
1588 return ret;
1589}
1590EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1591
1592/*
1593 * kill_something_info() interprets pid in interesting ways just like kill(2).
1594 *
1595 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1596 * is probably wrong. Should make it like BSD or SYSV.
1597 */
1598
1599static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1600{
1601 int ret;
1602
1603 if (pid > 0)
1604 return kill_proc_info(sig, info, pid);
1605
1606 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1607 if (pid == INT_MIN)
1608 return -ESRCH;
1609
1610 read_lock(&tasklist_lock);
1611 if (pid != -1) {
1612 ret = __kill_pgrp_info(sig, info,
1613 pid ? find_vpid(-pid) : task_pgrp(current));
1614 } else {
1615 int retval = 0, count = 0;
1616 struct task_struct * p;
1617
1618 for_each_process(p) {
1619 if (task_pid_vnr(p) > 1 &&
1620 !same_thread_group(p, current)) {
1621 int err = group_send_sig_info(sig, info, p,
1622 PIDTYPE_MAX);
1623 ++count;
1624 if (err != -EPERM)
1625 retval = err;
1626 }
1627 }
1628 ret = count ? retval : -ESRCH;
1629 }
1630 read_unlock(&tasklist_lock);
1631
1632 return ret;
1633}
1634
1635/*
1636 * These are for backward compatibility with the rest of the kernel source.
1637 */
1638
1639int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1640{
1641 /*
1642 * Make sure legacy kernel users don't send in bad values
1643 * (normal paths check this in check_kill_permission).
1644 */
1645 if (!valid_signal(sig))
1646 return -EINVAL;
1647
1648 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1649}
1650EXPORT_SYMBOL(send_sig_info);
1651
1652#define __si_special(priv) \
1653 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1654
1655int
1656send_sig(int sig, struct task_struct *p, int priv)
1657{
1658 return send_sig_info(sig, __si_special(priv), p);
1659}
1660EXPORT_SYMBOL(send_sig);
1661
1662void force_sig(int sig)
1663{
1664 struct kernel_siginfo info;
1665
1666 clear_siginfo(&info);
1667 info.si_signo = sig;
1668 info.si_errno = 0;
1669 info.si_code = SI_KERNEL;
1670 info.si_pid = 0;
1671 info.si_uid = 0;
1672 force_sig_info(&info);
1673}
1674EXPORT_SYMBOL(force_sig);
1675
1676void force_fatal_sig(int sig)
1677{
1678 struct kernel_siginfo info;
1679
1680 clear_siginfo(&info);
1681 info.si_signo = sig;
1682 info.si_errno = 0;
1683 info.si_code = SI_KERNEL;
1684 info.si_pid = 0;
1685 info.si_uid = 0;
1686 force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
1687}
1688
1689void force_exit_sig(int sig)
1690{
1691 struct kernel_siginfo info;
1692
1693 clear_siginfo(&info);
1694 info.si_signo = sig;
1695 info.si_errno = 0;
1696 info.si_code = SI_KERNEL;
1697 info.si_pid = 0;
1698 info.si_uid = 0;
1699 force_sig_info_to_task(&info, current, HANDLER_EXIT);
1700}
1701
1702/*
1703 * When things go south during signal handling, we
1704 * will force a SIGSEGV. And if the signal that caused
1705 * the problem was already a SIGSEGV, we'll want to
1706 * make sure we don't even try to deliver the signal..
1707 */
1708void force_sigsegv(int sig)
1709{
1710 if (sig == SIGSEGV)
1711 force_fatal_sig(SIGSEGV);
1712 else
1713 force_sig(SIGSEGV);
1714}
1715
1716int force_sig_fault_to_task(int sig, int code, void __user *addr,
1717 struct task_struct *t)
1718{
1719 struct kernel_siginfo info;
1720
1721 clear_siginfo(&info);
1722 info.si_signo = sig;
1723 info.si_errno = 0;
1724 info.si_code = code;
1725 info.si_addr = addr;
1726 return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
1727}
1728
1729int force_sig_fault(int sig, int code, void __user *addr)
1730{
1731 return force_sig_fault_to_task(sig, code, addr, current);
1732}
1733
1734int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t)
1735{
1736 struct kernel_siginfo info;
1737
1738 clear_siginfo(&info);
1739 info.si_signo = sig;
1740 info.si_errno = 0;
1741 info.si_code = code;
1742 info.si_addr = addr;
1743 return send_sig_info(info.si_signo, &info, t);
1744}
1745
1746int force_sig_mceerr(int code, void __user *addr, short lsb)
1747{
1748 struct kernel_siginfo info;
1749
1750 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1751 clear_siginfo(&info);
1752 info.si_signo = SIGBUS;
1753 info.si_errno = 0;
1754 info.si_code = code;
1755 info.si_addr = addr;
1756 info.si_addr_lsb = lsb;
1757 return force_sig_info(&info);
1758}
1759
1760int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1761{
1762 struct kernel_siginfo info;
1763
1764 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1765 clear_siginfo(&info);
1766 info.si_signo = SIGBUS;
1767 info.si_errno = 0;
1768 info.si_code = code;
1769 info.si_addr = addr;
1770 info.si_addr_lsb = lsb;
1771 return send_sig_info(info.si_signo, &info, t);
1772}
1773EXPORT_SYMBOL(send_sig_mceerr);
1774
1775int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1776{
1777 struct kernel_siginfo info;
1778
1779 clear_siginfo(&info);
1780 info.si_signo = SIGSEGV;
1781 info.si_errno = 0;
1782 info.si_code = SEGV_BNDERR;
1783 info.si_addr = addr;
1784 info.si_lower = lower;
1785 info.si_upper = upper;
1786 return force_sig_info(&info);
1787}
1788
1789#ifdef SEGV_PKUERR
1790int force_sig_pkuerr(void __user *addr, u32 pkey)
1791{
1792 struct kernel_siginfo info;
1793
1794 clear_siginfo(&info);
1795 info.si_signo = SIGSEGV;
1796 info.si_errno = 0;
1797 info.si_code = SEGV_PKUERR;
1798 info.si_addr = addr;
1799 info.si_pkey = pkey;
1800 return force_sig_info(&info);
1801}
1802#endif
1803
1804int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1805{
1806 struct kernel_siginfo info;
1807
1808 clear_siginfo(&info);
1809 info.si_signo = SIGTRAP;
1810 info.si_errno = 0;
1811 info.si_code = TRAP_PERF;
1812 info.si_addr = addr;
1813 info.si_perf_data = sig_data;
1814 info.si_perf_type = type;
1815
1816 /*
1817 * Signals generated by perf events should not terminate the whole
1818 * process if SIGTRAP is blocked, however, delivering the signal
1819 * asynchronously is better than not delivering at all. But tell user
1820 * space if the signal was asynchronous, so it can clearly be
1821 * distinguished from normal synchronous ones.
1822 */
1823 info.si_perf_flags = sigismember(¤t->blocked, info.si_signo) ?
1824 TRAP_PERF_FLAG_ASYNC :
1825 0;
1826
1827 return send_sig_info(info.si_signo, &info, current);
1828}
1829
1830/**
1831 * force_sig_seccomp - signals the task to allow in-process syscall emulation
1832 * @syscall: syscall number to send to userland
1833 * @reason: filter-supplied reason code to send to userland (via si_errno)
1834 * @force_coredump: true to trigger a coredump
1835 *
1836 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1837 */
1838int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1839{
1840 struct kernel_siginfo info;
1841
1842 clear_siginfo(&info);
1843 info.si_signo = SIGSYS;
1844 info.si_code = SYS_SECCOMP;
1845 info.si_call_addr = (void __user *)KSTK_EIP(current);
1846 info.si_errno = reason;
1847 info.si_arch = syscall_get_arch(current);
1848 info.si_syscall = syscall;
1849 return force_sig_info_to_task(&info, current,
1850 force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1851}
1852
1853/* For the crazy architectures that include trap information in
1854 * the errno field, instead of an actual errno value.
1855 */
1856int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1857{
1858 struct kernel_siginfo info;
1859
1860 clear_siginfo(&info);
1861 info.si_signo = SIGTRAP;
1862 info.si_errno = errno;
1863 info.si_code = TRAP_HWBKPT;
1864 info.si_addr = addr;
1865 return force_sig_info(&info);
1866}
1867
1868/* For the rare architectures that include trap information using
1869 * si_trapno.
1870 */
1871int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1872{
1873 struct kernel_siginfo info;
1874
1875 clear_siginfo(&info);
1876 info.si_signo = sig;
1877 info.si_errno = 0;
1878 info.si_code = code;
1879 info.si_addr = addr;
1880 info.si_trapno = trapno;
1881 return force_sig_info(&info);
1882}
1883
1884/* For the rare architectures that include trap information using
1885 * si_trapno.
1886 */
1887int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1888 struct task_struct *t)
1889{
1890 struct kernel_siginfo info;
1891
1892 clear_siginfo(&info);
1893 info.si_signo = sig;
1894 info.si_errno = 0;
1895 info.si_code = code;
1896 info.si_addr = addr;
1897 info.si_trapno = trapno;
1898 return send_sig_info(info.si_signo, &info, t);
1899}
1900
1901int kill_pgrp(struct pid *pid, int sig, int priv)
1902{
1903 int ret;
1904
1905 read_lock(&tasklist_lock);
1906 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1907 read_unlock(&tasklist_lock);
1908
1909 return ret;
1910}
1911EXPORT_SYMBOL(kill_pgrp);
1912
1913int kill_pid(struct pid *pid, int sig, int priv)
1914{
1915 return kill_pid_info(sig, __si_special(priv), pid);
1916}
1917EXPORT_SYMBOL(kill_pid);
1918
1919/*
1920 * These functions support sending signals using preallocated sigqueue
1921 * structures. This is needed "because realtime applications cannot
1922 * afford to lose notifications of asynchronous events, like timer
1923 * expirations or I/O completions". In the case of POSIX Timers
1924 * we allocate the sigqueue structure from the timer_create. If this
1925 * allocation fails we are able to report the failure to the application
1926 * with an EAGAIN error.
1927 */
1928struct sigqueue *sigqueue_alloc(void)
1929{
1930 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1931}
1932
1933void sigqueue_free(struct sigqueue *q)
1934{
1935 unsigned long flags;
1936 spinlock_t *lock = ¤t->sighand->siglock;
1937
1938 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1939 /*
1940 * We must hold ->siglock while testing q->list
1941 * to serialize with collect_signal() or with
1942 * __exit_signal()->flush_sigqueue().
1943 */
1944 spin_lock_irqsave(lock, flags);
1945 q->flags &= ~SIGQUEUE_PREALLOC;
1946 /*
1947 * If it is queued it will be freed when dequeued,
1948 * like the "regular" sigqueue.
1949 */
1950 if (!list_empty(&q->list))
1951 q = NULL;
1952 spin_unlock_irqrestore(lock, flags);
1953
1954 if (q)
1955 __sigqueue_free(q);
1956}
1957
1958int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1959{
1960 int sig = q->info.si_signo;
1961 struct sigpending *pending;
1962 struct task_struct *t;
1963 unsigned long flags;
1964 int ret, result;
1965
1966 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1967
1968 ret = -1;
1969 rcu_read_lock();
1970
1971 /*
1972 * This function is used by POSIX timers to deliver a timer signal.
1973 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1974 * set), the signal must be delivered to the specific thread (queues
1975 * into t->pending).
1976 *
1977 * Where type is not PIDTYPE_PID, signals must be delivered to the
1978 * process. In this case, prefer to deliver to current if it is in
1979 * the same thread group as the target process, which avoids
1980 * unnecessarily waking up a potentially idle task.
1981 */
1982 t = pid_task(pid, type);
1983 if (!t)
1984 goto ret;
1985 if (type != PIDTYPE_PID && same_thread_group(t, current))
1986 t = current;
1987 if (!likely(lock_task_sighand(t, &flags)))
1988 goto ret;
1989
1990 ret = 1; /* the signal is ignored */
1991 result = TRACE_SIGNAL_IGNORED;
1992 if (!prepare_signal(sig, t, false))
1993 goto out;
1994
1995 ret = 0;
1996 if (unlikely(!list_empty(&q->list))) {
1997 /*
1998 * If an SI_TIMER entry is already queue just increment
1999 * the overrun count.
2000 */
2001 BUG_ON(q->info.si_code != SI_TIMER);
2002 q->info.si_overrun++;
2003 result = TRACE_SIGNAL_ALREADY_PENDING;
2004 goto out;
2005 }
2006 q->info.si_overrun = 0;
2007
2008 signalfd_notify(t, sig);
2009 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
2010 list_add_tail(&q->list, &pending->list);
2011 sigaddset(&pending->signal, sig);
2012 complete_signal(sig, t, type);
2013 result = TRACE_SIGNAL_DELIVERED;
2014out:
2015 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
2016 unlock_task_sighand(t, &flags);
2017ret:
2018 rcu_read_unlock();
2019 return ret;
2020}
2021
2022static void do_notify_pidfd(struct task_struct *task)
2023{
2024 struct pid *pid;
2025
2026 WARN_ON(task->exit_state == 0);
2027 pid = task_pid(task);
2028 wake_up_all(&pid->wait_pidfd);
2029}
2030
2031/*
2032 * Let a parent know about the death of a child.
2033 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2034 *
2035 * Returns true if our parent ignored us and so we've switched to
2036 * self-reaping.
2037 */
2038bool do_notify_parent(struct task_struct *tsk, int sig)
2039{
2040 struct kernel_siginfo info;
2041 unsigned long flags;
2042 struct sighand_struct *psig;
2043 bool autoreap = false;
2044 u64 utime, stime;
2045
2046 WARN_ON_ONCE(sig == -1);
2047
2048 /* do_notify_parent_cldstop should have been called instead. */
2049 WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2050
2051 WARN_ON_ONCE(!tsk->ptrace &&
2052 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2053
2054 /* Wake up all pidfd waiters */
2055 do_notify_pidfd(tsk);
2056
2057 if (sig != SIGCHLD) {
2058 /*
2059 * This is only possible if parent == real_parent.
2060 * Check if it has changed security domain.
2061 */
2062 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2063 sig = SIGCHLD;
2064 }
2065
2066 clear_siginfo(&info);
2067 info.si_signo = sig;
2068 info.si_errno = 0;
2069 /*
2070 * We are under tasklist_lock here so our parent is tied to
2071 * us and cannot change.
2072 *
2073 * task_active_pid_ns will always return the same pid namespace
2074 * until a task passes through release_task.
2075 *
2076 * write_lock() currently calls preempt_disable() which is the
2077 * same as rcu_read_lock(), but according to Oleg, this is not
2078 * correct to rely on this
2079 */
2080 rcu_read_lock();
2081 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2082 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2083 task_uid(tsk));
2084 rcu_read_unlock();
2085
2086 task_cputime(tsk, &utime, &stime);
2087 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2088 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2089
2090 info.si_status = tsk->exit_code & 0x7f;
2091 if (tsk->exit_code & 0x80)
2092 info.si_code = CLD_DUMPED;
2093 else if (tsk->exit_code & 0x7f)
2094 info.si_code = CLD_KILLED;
2095 else {
2096 info.si_code = CLD_EXITED;
2097 info.si_status = tsk->exit_code >> 8;
2098 }
2099
2100 psig = tsk->parent->sighand;
2101 spin_lock_irqsave(&psig->siglock, flags);
2102 if (!tsk->ptrace && sig == SIGCHLD &&
2103 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2104 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2105 /*
2106 * We are exiting and our parent doesn't care. POSIX.1
2107 * defines special semantics for setting SIGCHLD to SIG_IGN
2108 * or setting the SA_NOCLDWAIT flag: we should be reaped
2109 * automatically and not left for our parent's wait4 call.
2110 * Rather than having the parent do it as a magic kind of
2111 * signal handler, we just set this to tell do_exit that we
2112 * can be cleaned up without becoming a zombie. Note that
2113 * we still call __wake_up_parent in this case, because a
2114 * blocked sys_wait4 might now return -ECHILD.
2115 *
2116 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2117 * is implementation-defined: we do (if you don't want
2118 * it, just use SIG_IGN instead).
2119 */
2120 autoreap = true;
2121 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2122 sig = 0;
2123 }
2124 /*
2125 * Send with __send_signal as si_pid and si_uid are in the
2126 * parent's namespaces.
2127 */
2128 if (valid_signal(sig) && sig)
2129 __send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2130 __wake_up_parent(tsk, tsk->parent);
2131 spin_unlock_irqrestore(&psig->siglock, flags);
2132
2133 return autoreap;
2134}
2135
2136/**
2137 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2138 * @tsk: task reporting the state change
2139 * @for_ptracer: the notification is for ptracer
2140 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2141 *
2142 * Notify @tsk's parent that the stopped/continued state has changed. If
2143 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2144 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2145 *
2146 * CONTEXT:
2147 * Must be called with tasklist_lock at least read locked.
2148 */
2149static void do_notify_parent_cldstop(struct task_struct *tsk,
2150 bool for_ptracer, int why)
2151{
2152 struct kernel_siginfo info;
2153 unsigned long flags;
2154 struct task_struct *parent;
2155 struct sighand_struct *sighand;
2156 u64 utime, stime;
2157
2158 if (for_ptracer) {
2159 parent = tsk->parent;
2160 } else {
2161 tsk = tsk->group_leader;
2162 parent = tsk->real_parent;
2163 }
2164
2165 clear_siginfo(&info);
2166 info.si_signo = SIGCHLD;
2167 info.si_errno = 0;
2168 /*
2169 * see comment in do_notify_parent() about the following 4 lines
2170 */
2171 rcu_read_lock();
2172 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2173 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2174 rcu_read_unlock();
2175
2176 task_cputime(tsk, &utime, &stime);
2177 info.si_utime = nsec_to_clock_t(utime);
2178 info.si_stime = nsec_to_clock_t(stime);
2179
2180 info.si_code = why;
2181 switch (why) {
2182 case CLD_CONTINUED:
2183 info.si_status = SIGCONT;
2184 break;
2185 case CLD_STOPPED:
2186 info.si_status = tsk->signal->group_exit_code & 0x7f;
2187 break;
2188 case CLD_TRAPPED:
2189 info.si_status = tsk->exit_code & 0x7f;
2190 break;
2191 default:
2192 BUG();
2193 }
2194
2195 sighand = parent->sighand;
2196 spin_lock_irqsave(&sighand->siglock, flags);
2197 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2198 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2199 send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID);
2200 /*
2201 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2202 */
2203 __wake_up_parent(tsk, parent);
2204 spin_unlock_irqrestore(&sighand->siglock, flags);
2205}
2206
2207/*
2208 * This must be called with current->sighand->siglock held.
2209 *
2210 * This should be the path for all ptrace stops.
2211 * We always set current->last_siginfo while stopped here.
2212 * That makes it a way to test a stopped process for
2213 * being ptrace-stopped vs being job-control-stopped.
2214 *
2215 * Returns the signal the ptracer requested the code resume
2216 * with. If the code did not stop because the tracer is gone,
2217 * the stop signal remains unchanged unless clear_code.
2218 */
2219static int ptrace_stop(int exit_code, int why, unsigned long message,
2220 kernel_siginfo_t *info)
2221 __releases(¤t->sighand->siglock)
2222 __acquires(¤t->sighand->siglock)
2223{
2224 bool gstop_done = false;
2225
2226 if (arch_ptrace_stop_needed()) {
2227 /*
2228 * The arch code has something special to do before a
2229 * ptrace stop. This is allowed to block, e.g. for faults
2230 * on user stack pages. We can't keep the siglock while
2231 * calling arch_ptrace_stop, so we must release it now.
2232 * To preserve proper semantics, we must do this before
2233 * any signal bookkeeping like checking group_stop_count.
2234 */
2235 spin_unlock_irq(¤t->sighand->siglock);
2236 arch_ptrace_stop();
2237 spin_lock_irq(¤t->sighand->siglock);
2238 }
2239
2240 /*
2241 * After this point ptrace_signal_wake_up or signal_wake_up
2242 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
2243 * signal comes in. Handle previous ptrace_unlinks and fatal
2244 * signals here to prevent ptrace_stop sleeping in schedule.
2245 */
2246 if (!current->ptrace || __fatal_signal_pending(current))
2247 return exit_code;
2248
2249 set_special_state(TASK_TRACED);
2250 current->jobctl |= JOBCTL_TRACED;
2251
2252 /*
2253 * We're committing to trapping. TRACED should be visible before
2254 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2255 * Also, transition to TRACED and updates to ->jobctl should be
2256 * atomic with respect to siglock and should be done after the arch
2257 * hook as siglock is released and regrabbed across it.
2258 *
2259 * TRACER TRACEE
2260 *
2261 * ptrace_attach()
2262 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2263 * do_wait()
2264 * set_current_state() smp_wmb();
2265 * ptrace_do_wait()
2266 * wait_task_stopped()
2267 * task_stopped_code()
2268 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2269 */
2270 smp_wmb();
2271
2272 current->ptrace_message = message;
2273 current->last_siginfo = info;
2274 current->exit_code = exit_code;
2275
2276 /*
2277 * If @why is CLD_STOPPED, we're trapping to participate in a group
2278 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2279 * across siglock relocks since INTERRUPT was scheduled, PENDING
2280 * could be clear now. We act as if SIGCONT is received after
2281 * TASK_TRACED is entered - ignore it.
2282 */
2283 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2284 gstop_done = task_participate_group_stop(current);
2285
2286 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2287 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2288 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2289 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2290
2291 /* entering a trap, clear TRAPPING */
2292 task_clear_jobctl_trapping(current);
2293
2294 spin_unlock_irq(¤t->sighand->siglock);
2295 read_lock(&tasklist_lock);
2296 /*
2297 * Notify parents of the stop.
2298 *
2299 * While ptraced, there are two parents - the ptracer and
2300 * the real_parent of the group_leader. The ptracer should
2301 * know about every stop while the real parent is only
2302 * interested in the completion of group stop. The states
2303 * for the two don't interact with each other. Notify
2304 * separately unless they're gonna be duplicates.
2305 */
2306 if (current->ptrace)
2307 do_notify_parent_cldstop(current, true, why);
2308 if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2309 do_notify_parent_cldstop(current, false, why);
2310
2311 /*
2312 * The previous do_notify_parent_cldstop() invocation woke ptracer.
2313 * One a PREEMPTION kernel this can result in preemption requirement
2314 * which will be fulfilled after read_unlock() and the ptracer will be
2315 * put on the CPU.
2316 * The ptracer is in wait_task_inactive(, __TASK_TRACED) waiting for
2317 * this task wait in schedule(). If this task gets preempted then it
2318 * remains enqueued on the runqueue. The ptracer will observe this and
2319 * then sleep for a delay of one HZ tick. In the meantime this task
2320 * gets scheduled, enters schedule() and will wait for the ptracer.
2321 *
2322 * This preemption point is not bad from a correctness point of
2323 * view but extends the runtime by one HZ tick time due to the
2324 * ptracer's sleep. The preempt-disable section ensures that there
2325 * will be no preemption between unlock and schedule() and so
2326 * improving the performance since the ptracer will observe that
2327 * the tracee is scheduled out once it gets on the CPU.
2328 *
2329 * On PREEMPT_RT locking tasklist_lock does not disable preemption.
2330 * Therefore the task can be preempted after do_notify_parent_cldstop()
2331 * before unlocking tasklist_lock so there is no benefit in doing this.
2332 *
2333 * In fact disabling preemption is harmful on PREEMPT_RT because
2334 * the spinlock_t in cgroup_enter_frozen() must not be acquired
2335 * with preemption disabled due to the 'sleeping' spinlock
2336 * substitution of RT.
2337 */
2338 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2339 preempt_disable();
2340 read_unlock(&tasklist_lock);
2341 cgroup_enter_frozen();
2342 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2343 preempt_enable_no_resched();
2344 schedule();
2345 cgroup_leave_frozen(true);
2346
2347 /*
2348 * We are back. Now reacquire the siglock before touching
2349 * last_siginfo, so that we are sure to have synchronized with
2350 * any signal-sending on another CPU that wants to examine it.
2351 */
2352 spin_lock_irq(¤t->sighand->siglock);
2353 exit_code = current->exit_code;
2354 current->last_siginfo = NULL;
2355 current->ptrace_message = 0;
2356 current->exit_code = 0;
2357
2358 /* LISTENING can be set only during STOP traps, clear it */
2359 current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2360
2361 /*
2362 * Queued signals ignored us while we were stopped for tracing.
2363 * So check for any that we should take before resuming user mode.
2364 * This sets TIF_SIGPENDING, but never clears it.
2365 */
2366 recalc_sigpending_tsk(current);
2367 return exit_code;
2368}
2369
2370static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2371{
2372 kernel_siginfo_t info;
2373
2374 clear_siginfo(&info);
2375 info.si_signo = signr;
2376 info.si_code = exit_code;
2377 info.si_pid = task_pid_vnr(current);
2378 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2379
2380 /* Let the debugger run. */
2381 return ptrace_stop(exit_code, why, message, &info);
2382}
2383
2384int ptrace_notify(int exit_code, unsigned long message)
2385{
2386 int signr;
2387
2388 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2389 if (unlikely(task_work_pending(current)))
2390 task_work_run();
2391
2392 spin_lock_irq(¤t->sighand->siglock);
2393 signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2394 spin_unlock_irq(¤t->sighand->siglock);
2395 return signr;
2396}
2397
2398/**
2399 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2400 * @signr: signr causing group stop if initiating
2401 *
2402 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2403 * and participate in it. If already set, participate in the existing
2404 * group stop. If participated in a group stop (and thus slept), %true is
2405 * returned with siglock released.
2406 *
2407 * If ptraced, this function doesn't handle stop itself. Instead,
2408 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2409 * untouched. The caller must ensure that INTERRUPT trap handling takes
2410 * places afterwards.
2411 *
2412 * CONTEXT:
2413 * Must be called with @current->sighand->siglock held, which is released
2414 * on %true return.
2415 *
2416 * RETURNS:
2417 * %false if group stop is already cancelled or ptrace trap is scheduled.
2418 * %true if participated in group stop.
2419 */
2420static bool do_signal_stop(int signr)
2421 __releases(¤t->sighand->siglock)
2422{
2423 struct signal_struct *sig = current->signal;
2424
2425 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2426 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2427 struct task_struct *t;
2428
2429 /* signr will be recorded in task->jobctl for retries */
2430 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2431
2432 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2433 unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2434 unlikely(sig->group_exec_task))
2435 return false;
2436 /*
2437 * There is no group stop already in progress. We must
2438 * initiate one now.
2439 *
2440 * While ptraced, a task may be resumed while group stop is
2441 * still in effect and then receive a stop signal and
2442 * initiate another group stop. This deviates from the
2443 * usual behavior as two consecutive stop signals can't
2444 * cause two group stops when !ptraced. That is why we
2445 * also check !task_is_stopped(t) below.
2446 *
2447 * The condition can be distinguished by testing whether
2448 * SIGNAL_STOP_STOPPED is already set. Don't generate
2449 * group_exit_code in such case.
2450 *
2451 * This is not necessary for SIGNAL_STOP_CONTINUED because
2452 * an intervening stop signal is required to cause two
2453 * continued events regardless of ptrace.
2454 */
2455 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2456 sig->group_exit_code = signr;
2457
2458 sig->group_stop_count = 0;
2459 if (task_set_jobctl_pending(current, signr | gstop))
2460 sig->group_stop_count++;
2461
2462 for_other_threads(current, t) {
2463 /*
2464 * Setting state to TASK_STOPPED for a group
2465 * stop is always done with the siglock held,
2466 * so this check has no races.
2467 */
2468 if (!task_is_stopped(t) &&
2469 task_set_jobctl_pending(t, signr | gstop)) {
2470 sig->group_stop_count++;
2471 if (likely(!(t->ptrace & PT_SEIZED)))
2472 signal_wake_up(t, 0);
2473 else
2474 ptrace_trap_notify(t);
2475 }
2476 }
2477 }
2478
2479 if (likely(!current->ptrace)) {
2480 int notify = 0;
2481
2482 /*
2483 * If there are no other threads in the group, or if there
2484 * is a group stop in progress and we are the last to stop,
2485 * report to the parent.
2486 */
2487 if (task_participate_group_stop(current))
2488 notify = CLD_STOPPED;
2489
2490 current->jobctl |= JOBCTL_STOPPED;
2491 set_special_state(TASK_STOPPED);
2492 spin_unlock_irq(¤t->sighand->siglock);
2493
2494 /*
2495 * Notify the parent of the group stop completion. Because
2496 * we're not holding either the siglock or tasklist_lock
2497 * here, ptracer may attach inbetween; however, this is for
2498 * group stop and should always be delivered to the real
2499 * parent of the group leader. The new ptracer will get
2500 * its notification when this task transitions into
2501 * TASK_TRACED.
2502 */
2503 if (notify) {
2504 read_lock(&tasklist_lock);
2505 do_notify_parent_cldstop(current, false, notify);
2506 read_unlock(&tasklist_lock);
2507 }
2508
2509 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2510 cgroup_enter_frozen();
2511 schedule();
2512 return true;
2513 } else {
2514 /*
2515 * While ptraced, group stop is handled by STOP trap.
2516 * Schedule it and let the caller deal with it.
2517 */
2518 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2519 return false;
2520 }
2521}
2522
2523/**
2524 * do_jobctl_trap - take care of ptrace jobctl traps
2525 *
2526 * When PT_SEIZED, it's used for both group stop and explicit
2527 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2528 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2529 * the stop signal; otherwise, %SIGTRAP.
2530 *
2531 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2532 * number as exit_code and no siginfo.
2533 *
2534 * CONTEXT:
2535 * Must be called with @current->sighand->siglock held, which may be
2536 * released and re-acquired before returning with intervening sleep.
2537 */
2538static void do_jobctl_trap(void)
2539{
2540 struct signal_struct *signal = current->signal;
2541 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2542
2543 if (current->ptrace & PT_SEIZED) {
2544 if (!signal->group_stop_count &&
2545 !(signal->flags & SIGNAL_STOP_STOPPED))
2546 signr = SIGTRAP;
2547 WARN_ON_ONCE(!signr);
2548 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2549 CLD_STOPPED, 0);
2550 } else {
2551 WARN_ON_ONCE(!signr);
2552 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2553 }
2554}
2555
2556/**
2557 * do_freezer_trap - handle the freezer jobctl trap
2558 *
2559 * Puts the task into frozen state, if only the task is not about to quit.
2560 * In this case it drops JOBCTL_TRAP_FREEZE.
2561 *
2562 * CONTEXT:
2563 * Must be called with @current->sighand->siglock held,
2564 * which is always released before returning.
2565 */
2566static void do_freezer_trap(void)
2567 __releases(¤t->sighand->siglock)
2568{
2569 /*
2570 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2571 * let's make another loop to give it a chance to be handled.
2572 * In any case, we'll return back.
2573 */
2574 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2575 JOBCTL_TRAP_FREEZE) {
2576 spin_unlock_irq(¤t->sighand->siglock);
2577 return;
2578 }
2579
2580 /*
2581 * Now we're sure that there is no pending fatal signal and no
2582 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2583 * immediately (if there is a non-fatal signal pending), and
2584 * put the task into sleep.
2585 */
2586 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2587 clear_thread_flag(TIF_SIGPENDING);
2588 spin_unlock_irq(¤t->sighand->siglock);
2589 cgroup_enter_frozen();
2590 schedule();
2591}
2592
2593static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2594{
2595 /*
2596 * We do not check sig_kernel_stop(signr) but set this marker
2597 * unconditionally because we do not know whether debugger will
2598 * change signr. This flag has no meaning unless we are going
2599 * to stop after return from ptrace_stop(). In this case it will
2600 * be checked in do_signal_stop(), we should only stop if it was
2601 * not cleared by SIGCONT while we were sleeping. See also the
2602 * comment in dequeue_signal().
2603 */
2604 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2605 signr = ptrace_stop(signr, CLD_TRAPPED, 0, info);
2606
2607 /* We're back. Did the debugger cancel the sig? */
2608 if (signr == 0)
2609 return signr;
2610
2611 /*
2612 * Update the siginfo structure if the signal has
2613 * changed. If the debugger wanted something
2614 * specific in the siginfo structure then it should
2615 * have updated *info via PTRACE_SETSIGINFO.
2616 */
2617 if (signr != info->si_signo) {
2618 clear_siginfo(info);
2619 info->si_signo = signr;
2620 info->si_errno = 0;
2621 info->si_code = SI_USER;
2622 rcu_read_lock();
2623 info->si_pid = task_pid_vnr(current->parent);
2624 info->si_uid = from_kuid_munged(current_user_ns(),
2625 task_uid(current->parent));
2626 rcu_read_unlock();
2627 }
2628
2629 /* If the (new) signal is now blocked, requeue it. */
2630 if (sigismember(¤t->blocked, signr) ||
2631 fatal_signal_pending(current)) {
2632 send_signal_locked(signr, info, current, type);
2633 signr = 0;
2634 }
2635
2636 return signr;
2637}
2638
2639static void hide_si_addr_tag_bits(struct ksignal *ksig)
2640{
2641 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2642 case SIL_FAULT:
2643 case SIL_FAULT_TRAPNO:
2644 case SIL_FAULT_MCEERR:
2645 case SIL_FAULT_BNDERR:
2646 case SIL_FAULT_PKUERR:
2647 case SIL_FAULT_PERF_EVENT:
2648 ksig->info.si_addr = arch_untagged_si_addr(
2649 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2650 break;
2651 case SIL_KILL:
2652 case SIL_TIMER:
2653 case SIL_POLL:
2654 case SIL_CHLD:
2655 case SIL_RT:
2656 case SIL_SYS:
2657 break;
2658 }
2659}
2660
2661bool get_signal(struct ksignal *ksig)
2662{
2663 struct sighand_struct *sighand = current->sighand;
2664 struct signal_struct *signal = current->signal;
2665 int signr;
2666
2667 clear_notify_signal();
2668 if (unlikely(task_work_pending(current)))
2669 task_work_run();
2670
2671 if (!task_sigpending(current))
2672 return false;
2673
2674 if (unlikely(uprobe_deny_signal()))
2675 return false;
2676
2677 /*
2678 * Do this once, we can't return to user-mode if freezing() == T.
2679 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2680 * thus do not need another check after return.
2681 */
2682 try_to_freeze();
2683
2684relock:
2685 spin_lock_irq(&sighand->siglock);
2686
2687 /*
2688 * Every stopped thread goes here after wakeup. Check to see if
2689 * we should notify the parent, prepare_signal(SIGCONT) encodes
2690 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2691 */
2692 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2693 int why;
2694
2695 if (signal->flags & SIGNAL_CLD_CONTINUED)
2696 why = CLD_CONTINUED;
2697 else
2698 why = CLD_STOPPED;
2699
2700 signal->flags &= ~SIGNAL_CLD_MASK;
2701
2702 spin_unlock_irq(&sighand->siglock);
2703
2704 /*
2705 * Notify the parent that we're continuing. This event is
2706 * always per-process and doesn't make whole lot of sense
2707 * for ptracers, who shouldn't consume the state via
2708 * wait(2) either, but, for backward compatibility, notify
2709 * the ptracer of the group leader too unless it's gonna be
2710 * a duplicate.
2711 */
2712 read_lock(&tasklist_lock);
2713 do_notify_parent_cldstop(current, false, why);
2714
2715 if (ptrace_reparented(current->group_leader))
2716 do_notify_parent_cldstop(current->group_leader,
2717 true, why);
2718 read_unlock(&tasklist_lock);
2719
2720 goto relock;
2721 }
2722
2723 for (;;) {
2724 struct k_sigaction *ka;
2725 enum pid_type type;
2726
2727 /* Has this task already been marked for death? */
2728 if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2729 signal->group_exec_task) {
2730 clear_siginfo(&ksig->info);
2731 ksig->info.si_signo = signr = SIGKILL;
2732 sigdelset(¤t->pending.signal, SIGKILL);
2733 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2734 &sighand->action[SIGKILL - 1]);
2735 recalc_sigpending();
2736 goto fatal;
2737 }
2738
2739 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2740 do_signal_stop(0))
2741 goto relock;
2742
2743 if (unlikely(current->jobctl &
2744 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2745 if (current->jobctl & JOBCTL_TRAP_MASK) {
2746 do_jobctl_trap();
2747 spin_unlock_irq(&sighand->siglock);
2748 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2749 do_freezer_trap();
2750
2751 goto relock;
2752 }
2753
2754 /*
2755 * If the task is leaving the frozen state, let's update
2756 * cgroup counters and reset the frozen bit.
2757 */
2758 if (unlikely(cgroup_task_frozen(current))) {
2759 spin_unlock_irq(&sighand->siglock);
2760 cgroup_leave_frozen(false);
2761 goto relock;
2762 }
2763
2764 /*
2765 * Signals generated by the execution of an instruction
2766 * need to be delivered before any other pending signals
2767 * so that the instruction pointer in the signal stack
2768 * frame points to the faulting instruction.
2769 */
2770 type = PIDTYPE_PID;
2771 signr = dequeue_synchronous_signal(&ksig->info);
2772 if (!signr)
2773 signr = dequeue_signal(current, ¤t->blocked,
2774 &ksig->info, &type);
2775
2776 if (!signr)
2777 break; /* will return 0 */
2778
2779 if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2780 !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2781 signr = ptrace_signal(signr, &ksig->info, type);
2782 if (!signr)
2783 continue;
2784 }
2785
2786 ka = &sighand->action[signr-1];
2787
2788 /* Trace actually delivered signals. */
2789 trace_signal_deliver(signr, &ksig->info, ka);
2790
2791 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2792 continue;
2793 if (ka->sa.sa_handler != SIG_DFL) {
2794 /* Run the handler. */
2795 ksig->ka = *ka;
2796
2797 if (ka->sa.sa_flags & SA_ONESHOT)
2798 ka->sa.sa_handler = SIG_DFL;
2799
2800 break; /* will return non-zero "signr" value */
2801 }
2802
2803 /*
2804 * Now we are doing the default action for this signal.
2805 */
2806 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2807 continue;
2808
2809 /*
2810 * Global init gets no signals it doesn't want.
2811 * Container-init gets no signals it doesn't want from same
2812 * container.
2813 *
2814 * Note that if global/container-init sees a sig_kernel_only()
2815 * signal here, the signal must have been generated internally
2816 * or must have come from an ancestor namespace. In either
2817 * case, the signal cannot be dropped.
2818 */
2819 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2820 !sig_kernel_only(signr))
2821 continue;
2822
2823 if (sig_kernel_stop(signr)) {
2824 /*
2825 * The default action is to stop all threads in
2826 * the thread group. The job control signals
2827 * do nothing in an orphaned pgrp, but SIGSTOP
2828 * always works. Note that siglock needs to be
2829 * dropped during the call to is_orphaned_pgrp()
2830 * because of lock ordering with tasklist_lock.
2831 * This allows an intervening SIGCONT to be posted.
2832 * We need to check for that and bail out if necessary.
2833 */
2834 if (signr != SIGSTOP) {
2835 spin_unlock_irq(&sighand->siglock);
2836
2837 /* signals can be posted during this window */
2838
2839 if (is_current_pgrp_orphaned())
2840 goto relock;
2841
2842 spin_lock_irq(&sighand->siglock);
2843 }
2844
2845 if (likely(do_signal_stop(ksig->info.si_signo))) {
2846 /* It released the siglock. */
2847 goto relock;
2848 }
2849
2850 /*
2851 * We didn't actually stop, due to a race
2852 * with SIGCONT or something like that.
2853 */
2854 continue;
2855 }
2856
2857 fatal:
2858 spin_unlock_irq(&sighand->siglock);
2859 if (unlikely(cgroup_task_frozen(current)))
2860 cgroup_leave_frozen(true);
2861
2862 /*
2863 * Anything else is fatal, maybe with a core dump.
2864 */
2865 current->flags |= PF_SIGNALED;
2866
2867 if (sig_kernel_coredump(signr)) {
2868 if (print_fatal_signals)
2869 print_fatal_signal(ksig->info.si_signo);
2870 proc_coredump_connector(current);
2871 /*
2872 * If it was able to dump core, this kills all
2873 * other threads in the group and synchronizes with
2874 * their demise. If we lost the race with another
2875 * thread getting here, it set group_exit_code
2876 * first and our do_group_exit call below will use
2877 * that value and ignore the one we pass it.
2878 */
2879 do_coredump(&ksig->info);
2880 }
2881
2882 /*
2883 * PF_USER_WORKER threads will catch and exit on fatal signals
2884 * themselves. They have cleanup that must be performed, so
2885 * we cannot call do_exit() on their behalf.
2886 */
2887 if (current->flags & PF_USER_WORKER)
2888 goto out;
2889
2890 /*
2891 * Death signals, no core dump.
2892 */
2893 do_group_exit(ksig->info.si_signo);
2894 /* NOTREACHED */
2895 }
2896 spin_unlock_irq(&sighand->siglock);
2897out:
2898 ksig->sig = signr;
2899
2900 if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2901 hide_si_addr_tag_bits(ksig);
2902
2903 return ksig->sig > 0;
2904}
2905
2906/**
2907 * signal_delivered - called after signal delivery to update blocked signals
2908 * @ksig: kernel signal struct
2909 * @stepping: nonzero if debugger single-step or block-step in use
2910 *
2911 * This function should be called when a signal has successfully been
2912 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2913 * is always blocked), and the signal itself is blocked unless %SA_NODEFER
2914 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2915 */
2916static void signal_delivered(struct ksignal *ksig, int stepping)
2917{
2918 sigset_t blocked;
2919
2920 /* A signal was successfully delivered, and the
2921 saved sigmask was stored on the signal frame,
2922 and will be restored by sigreturn. So we can
2923 simply clear the restore sigmask flag. */
2924 clear_restore_sigmask();
2925
2926 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2927 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2928 sigaddset(&blocked, ksig->sig);
2929 set_current_blocked(&blocked);
2930 if (current->sas_ss_flags & SS_AUTODISARM)
2931 sas_ss_reset(current);
2932 if (stepping)
2933 ptrace_notify(SIGTRAP, 0);
2934}
2935
2936void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2937{
2938 if (failed)
2939 force_sigsegv(ksig->sig);
2940 else
2941 signal_delivered(ksig, stepping);
2942}
2943
2944/*
2945 * It could be that complete_signal() picked us to notify about the
2946 * group-wide signal. Other threads should be notified now to take
2947 * the shared signals in @which since we will not.
2948 */
2949static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2950{
2951 sigset_t retarget;
2952 struct task_struct *t;
2953
2954 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2955 if (sigisemptyset(&retarget))
2956 return;
2957
2958 for_other_threads(tsk, t) {
2959 if (t->flags & PF_EXITING)
2960 continue;
2961
2962 if (!has_pending_signals(&retarget, &t->blocked))
2963 continue;
2964 /* Remove the signals this thread can handle. */
2965 sigandsets(&retarget, &retarget, &t->blocked);
2966
2967 if (!task_sigpending(t))
2968 signal_wake_up(t, 0);
2969
2970 if (sigisemptyset(&retarget))
2971 break;
2972 }
2973}
2974
2975void exit_signals(struct task_struct *tsk)
2976{
2977 int group_stop = 0;
2978 sigset_t unblocked;
2979
2980 /*
2981 * @tsk is about to have PF_EXITING set - lock out users which
2982 * expect stable threadgroup.
2983 */
2984 cgroup_threadgroup_change_begin(tsk);
2985
2986 if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
2987 sched_mm_cid_exit_signals(tsk);
2988 tsk->flags |= PF_EXITING;
2989 cgroup_threadgroup_change_end(tsk);
2990 return;
2991 }
2992
2993 spin_lock_irq(&tsk->sighand->siglock);
2994 /*
2995 * From now this task is not visible for group-wide signals,
2996 * see wants_signal(), do_signal_stop().
2997 */
2998 sched_mm_cid_exit_signals(tsk);
2999 tsk->flags |= PF_EXITING;
3000
3001 cgroup_threadgroup_change_end(tsk);
3002
3003 if (!task_sigpending(tsk))
3004 goto out;
3005
3006 unblocked = tsk->blocked;
3007 signotset(&unblocked);
3008 retarget_shared_pending(tsk, &unblocked);
3009
3010 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3011 task_participate_group_stop(tsk))
3012 group_stop = CLD_STOPPED;
3013out:
3014 spin_unlock_irq(&tsk->sighand->siglock);
3015
3016 /*
3017 * If group stop has completed, deliver the notification. This
3018 * should always go to the real parent of the group leader.
3019 */
3020 if (unlikely(group_stop)) {
3021 read_lock(&tasklist_lock);
3022 do_notify_parent_cldstop(tsk, false, group_stop);
3023 read_unlock(&tasklist_lock);
3024 }
3025}
3026
3027/*
3028 * System call entry points.
3029 */
3030
3031/**
3032 * sys_restart_syscall - restart a system call
3033 */
3034SYSCALL_DEFINE0(restart_syscall)
3035{
3036 struct restart_block *restart = ¤t->restart_block;
3037 return restart->fn(restart);
3038}
3039
3040long do_no_restart_syscall(struct restart_block *param)
3041{
3042 return -EINTR;
3043}
3044
3045static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3046{
3047 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
3048 sigset_t newblocked;
3049 /* A set of now blocked but previously unblocked signals. */
3050 sigandnsets(&newblocked, newset, ¤t->blocked);
3051 retarget_shared_pending(tsk, &newblocked);
3052 }
3053 tsk->blocked = *newset;
3054 recalc_sigpending();
3055}
3056
3057/**
3058 * set_current_blocked - change current->blocked mask
3059 * @newset: new mask
3060 *
3061 * It is wrong to change ->blocked directly, this helper should be used
3062 * to ensure the process can't miss a shared signal we are going to block.
3063 */
3064void set_current_blocked(sigset_t *newset)
3065{
3066 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3067 __set_current_blocked(newset);
3068}
3069
3070void __set_current_blocked(const sigset_t *newset)
3071{
3072 struct task_struct *tsk = current;
3073
3074 /*
3075 * In case the signal mask hasn't changed, there is nothing we need
3076 * to do. The current->blocked shouldn't be modified by other task.
3077 */
3078 if (sigequalsets(&tsk->blocked, newset))
3079 return;
3080
3081 spin_lock_irq(&tsk->sighand->siglock);
3082 __set_task_blocked(tsk, newset);
3083 spin_unlock_irq(&tsk->sighand->siglock);
3084}
3085
3086/*
3087 * This is also useful for kernel threads that want to temporarily
3088 * (or permanently) block certain signals.
3089 *
3090 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3091 * interface happily blocks "unblockable" signals like SIGKILL
3092 * and friends.
3093 */
3094int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3095{
3096 struct task_struct *tsk = current;
3097 sigset_t newset;
3098
3099 /* Lockless, only current can change ->blocked, never from irq */
3100 if (oldset)
3101 *oldset = tsk->blocked;
3102
3103 switch (how) {
3104 case SIG_BLOCK:
3105 sigorsets(&newset, &tsk->blocked, set);
3106 break;
3107 case SIG_UNBLOCK:
3108 sigandnsets(&newset, &tsk->blocked, set);
3109 break;
3110 case SIG_SETMASK:
3111 newset = *set;
3112 break;
3113 default:
3114 return -EINVAL;
3115 }
3116
3117 __set_current_blocked(&newset);
3118 return 0;
3119}
3120EXPORT_SYMBOL(sigprocmask);
3121
3122/*
3123 * The api helps set app-provided sigmasks.
3124 *
3125 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3126 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3127 *
3128 * Note that it does set_restore_sigmask() in advance, so it must be always
3129 * paired with restore_saved_sigmask_unless() before return from syscall.
3130 */
3131int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3132{
3133 sigset_t kmask;
3134
3135 if (!umask)
3136 return 0;
3137 if (sigsetsize != sizeof(sigset_t))
3138 return -EINVAL;
3139 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3140 return -EFAULT;
3141
3142 set_restore_sigmask();
3143 current->saved_sigmask = current->blocked;
3144 set_current_blocked(&kmask);
3145
3146 return 0;
3147}
3148
3149#ifdef CONFIG_COMPAT
3150int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3151 size_t sigsetsize)
3152{
3153 sigset_t kmask;
3154
3155 if (!umask)
3156 return 0;
3157 if (sigsetsize != sizeof(compat_sigset_t))
3158 return -EINVAL;
3159 if (get_compat_sigset(&kmask, umask))
3160 return -EFAULT;
3161
3162 set_restore_sigmask();
3163 current->saved_sigmask = current->blocked;
3164 set_current_blocked(&kmask);
3165
3166 return 0;
3167}
3168#endif
3169
3170/**
3171 * sys_rt_sigprocmask - change the list of currently blocked signals
3172 * @how: whether to add, remove, or set signals
3173 * @nset: stores pending signals
3174 * @oset: previous value of signal mask if non-null
3175 * @sigsetsize: size of sigset_t type
3176 */
3177SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3178 sigset_t __user *, oset, size_t, sigsetsize)
3179{
3180 sigset_t old_set, new_set;
3181 int error;
3182
3183 /* XXX: Don't preclude handling different sized sigset_t's. */
3184 if (sigsetsize != sizeof(sigset_t))
3185 return -EINVAL;
3186
3187 old_set = current->blocked;
3188
3189 if (nset) {
3190 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3191 return -EFAULT;
3192 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3193
3194 error = sigprocmask(how, &new_set, NULL);
3195 if (error)
3196 return error;
3197 }
3198
3199 if (oset) {
3200 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3201 return -EFAULT;
3202 }
3203
3204 return 0;
3205}
3206
3207#ifdef CONFIG_COMPAT
3208COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3209 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3210{
3211 sigset_t old_set = current->blocked;
3212
3213 /* XXX: Don't preclude handling different sized sigset_t's. */
3214 if (sigsetsize != sizeof(sigset_t))
3215 return -EINVAL;
3216
3217 if (nset) {
3218 sigset_t new_set;
3219 int error;
3220 if (get_compat_sigset(&new_set, nset))
3221 return -EFAULT;
3222 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3223
3224 error = sigprocmask(how, &new_set, NULL);
3225 if (error)
3226 return error;
3227 }
3228 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3229}
3230#endif
3231
3232static void do_sigpending(sigset_t *set)
3233{
3234 spin_lock_irq(¤t->sighand->siglock);
3235 sigorsets(set, ¤t->pending.signal,
3236 ¤t->signal->shared_pending.signal);
3237 spin_unlock_irq(¤t->sighand->siglock);
3238
3239 /* Outside the lock because only this thread touches it. */
3240 sigandsets(set, ¤t->blocked, set);
3241}
3242
3243/**
3244 * sys_rt_sigpending - examine a pending signal that has been raised
3245 * while blocked
3246 * @uset: stores pending signals
3247 * @sigsetsize: size of sigset_t type or larger
3248 */
3249SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3250{
3251 sigset_t set;
3252
3253 if (sigsetsize > sizeof(*uset))
3254 return -EINVAL;
3255
3256 do_sigpending(&set);
3257
3258 if (copy_to_user(uset, &set, sigsetsize))
3259 return -EFAULT;
3260
3261 return 0;
3262}
3263
3264#ifdef CONFIG_COMPAT
3265COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3266 compat_size_t, sigsetsize)
3267{
3268 sigset_t set;
3269
3270 if (sigsetsize > sizeof(*uset))
3271 return -EINVAL;
3272
3273 do_sigpending(&set);
3274
3275 return put_compat_sigset(uset, &set, sigsetsize);
3276}
3277#endif
3278
3279static const struct {
3280 unsigned char limit, layout;
3281} sig_sicodes[] = {
3282 [SIGILL] = { NSIGILL, SIL_FAULT },
3283 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3284 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3285 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3286 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3287#if defined(SIGEMT)
3288 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3289#endif
3290 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3291 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3292 [SIGSYS] = { NSIGSYS, SIL_SYS },
3293};
3294
3295static bool known_siginfo_layout(unsigned sig, int si_code)
3296{
3297 if (si_code == SI_KERNEL)
3298 return true;
3299 else if ((si_code > SI_USER)) {
3300 if (sig_specific_sicodes(sig)) {
3301 if (si_code <= sig_sicodes[sig].limit)
3302 return true;
3303 }
3304 else if (si_code <= NSIGPOLL)
3305 return true;
3306 }
3307 else if (si_code >= SI_DETHREAD)
3308 return true;
3309 else if (si_code == SI_ASYNCNL)
3310 return true;
3311 return false;
3312}
3313
3314enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3315{
3316 enum siginfo_layout layout = SIL_KILL;
3317 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3318 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3319 (si_code <= sig_sicodes[sig].limit)) {
3320 layout = sig_sicodes[sig].layout;
3321 /* Handle the exceptions */
3322 if ((sig == SIGBUS) &&
3323 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3324 layout = SIL_FAULT_MCEERR;
3325 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3326 layout = SIL_FAULT_BNDERR;
3327#ifdef SEGV_PKUERR
3328 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3329 layout = SIL_FAULT_PKUERR;
3330#endif
3331 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3332 layout = SIL_FAULT_PERF_EVENT;
3333 else if (IS_ENABLED(CONFIG_SPARC) &&
3334 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3335 layout = SIL_FAULT_TRAPNO;
3336 else if (IS_ENABLED(CONFIG_ALPHA) &&
3337 ((sig == SIGFPE) ||
3338 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3339 layout = SIL_FAULT_TRAPNO;
3340 }
3341 else if (si_code <= NSIGPOLL)
3342 layout = SIL_POLL;
3343 } else {
3344 if (si_code == SI_TIMER)
3345 layout = SIL_TIMER;
3346 else if (si_code == SI_SIGIO)
3347 layout = SIL_POLL;
3348 else if (si_code < 0)
3349 layout = SIL_RT;
3350 }
3351 return layout;
3352}
3353
3354static inline char __user *si_expansion(const siginfo_t __user *info)
3355{
3356 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3357}
3358
3359int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3360{
3361 char __user *expansion = si_expansion(to);
3362 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3363 return -EFAULT;
3364 if (clear_user(expansion, SI_EXPANSION_SIZE))
3365 return -EFAULT;
3366 return 0;
3367}
3368
3369static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3370 const siginfo_t __user *from)
3371{
3372 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3373 char __user *expansion = si_expansion(from);
3374 char buf[SI_EXPANSION_SIZE];
3375 int i;
3376 /*
3377 * An unknown si_code might need more than
3378 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3379 * extra bytes are 0. This guarantees copy_siginfo_to_user
3380 * will return this data to userspace exactly.
3381 */
3382 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3383 return -EFAULT;
3384 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3385 if (buf[i] != 0)
3386 return -E2BIG;
3387 }
3388 }
3389 return 0;
3390}
3391
3392static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3393 const siginfo_t __user *from)
3394{
3395 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3396 return -EFAULT;
3397 to->si_signo = signo;
3398 return post_copy_siginfo_from_user(to, from);
3399}
3400
3401int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3402{
3403 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3404 return -EFAULT;
3405 return post_copy_siginfo_from_user(to, from);
3406}
3407
3408#ifdef CONFIG_COMPAT
3409/**
3410 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3411 * @to: compat siginfo destination
3412 * @from: kernel siginfo source
3413 *
3414 * Note: This function does not work properly for the SIGCHLD on x32, but
3415 * fortunately it doesn't have to. The only valid callers for this function are
3416 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3417 * The latter does not care because SIGCHLD will never cause a coredump.
3418 */
3419void copy_siginfo_to_external32(struct compat_siginfo *to,
3420 const struct kernel_siginfo *from)
3421{
3422 memset(to, 0, sizeof(*to));
3423
3424 to->si_signo = from->si_signo;
3425 to->si_errno = from->si_errno;
3426 to->si_code = from->si_code;
3427 switch(siginfo_layout(from->si_signo, from->si_code)) {
3428 case SIL_KILL:
3429 to->si_pid = from->si_pid;
3430 to->si_uid = from->si_uid;
3431 break;
3432 case SIL_TIMER:
3433 to->si_tid = from->si_tid;
3434 to->si_overrun = from->si_overrun;
3435 to->si_int = from->si_int;
3436 break;
3437 case SIL_POLL:
3438 to->si_band = from->si_band;
3439 to->si_fd = from->si_fd;
3440 break;
3441 case SIL_FAULT:
3442 to->si_addr = ptr_to_compat(from->si_addr);
3443 break;
3444 case SIL_FAULT_TRAPNO:
3445 to->si_addr = ptr_to_compat(from->si_addr);
3446 to->si_trapno = from->si_trapno;
3447 break;
3448 case SIL_FAULT_MCEERR:
3449 to->si_addr = ptr_to_compat(from->si_addr);
3450 to->si_addr_lsb = from->si_addr_lsb;
3451 break;
3452 case SIL_FAULT_BNDERR:
3453 to->si_addr = ptr_to_compat(from->si_addr);
3454 to->si_lower = ptr_to_compat(from->si_lower);
3455 to->si_upper = ptr_to_compat(from->si_upper);
3456 break;
3457 case SIL_FAULT_PKUERR:
3458 to->si_addr = ptr_to_compat(from->si_addr);
3459 to->si_pkey = from->si_pkey;
3460 break;
3461 case SIL_FAULT_PERF_EVENT:
3462 to->si_addr = ptr_to_compat(from->si_addr);
3463 to->si_perf_data = from->si_perf_data;
3464 to->si_perf_type = from->si_perf_type;
3465 to->si_perf_flags = from->si_perf_flags;
3466 break;
3467 case SIL_CHLD:
3468 to->si_pid = from->si_pid;
3469 to->si_uid = from->si_uid;
3470 to->si_status = from->si_status;
3471 to->si_utime = from->si_utime;
3472 to->si_stime = from->si_stime;
3473 break;
3474 case SIL_RT:
3475 to->si_pid = from->si_pid;
3476 to->si_uid = from->si_uid;
3477 to->si_int = from->si_int;
3478 break;
3479 case SIL_SYS:
3480 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3481 to->si_syscall = from->si_syscall;
3482 to->si_arch = from->si_arch;
3483 break;
3484 }
3485}
3486
3487int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3488 const struct kernel_siginfo *from)
3489{
3490 struct compat_siginfo new;
3491
3492 copy_siginfo_to_external32(&new, from);
3493 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3494 return -EFAULT;
3495 return 0;
3496}
3497
3498static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3499 const struct compat_siginfo *from)
3500{
3501 clear_siginfo(to);
3502 to->si_signo = from->si_signo;
3503 to->si_errno = from->si_errno;
3504 to->si_code = from->si_code;
3505 switch(siginfo_layout(from->si_signo, from->si_code)) {
3506 case SIL_KILL:
3507 to->si_pid = from->si_pid;
3508 to->si_uid = from->si_uid;
3509 break;
3510 case SIL_TIMER:
3511 to->si_tid = from->si_tid;
3512 to->si_overrun = from->si_overrun;
3513 to->si_int = from->si_int;
3514 break;
3515 case SIL_POLL:
3516 to->si_band = from->si_band;
3517 to->si_fd = from->si_fd;
3518 break;
3519 case SIL_FAULT:
3520 to->si_addr = compat_ptr(from->si_addr);
3521 break;
3522 case SIL_FAULT_TRAPNO:
3523 to->si_addr = compat_ptr(from->si_addr);
3524 to->si_trapno = from->si_trapno;
3525 break;
3526 case SIL_FAULT_MCEERR:
3527 to->si_addr = compat_ptr(from->si_addr);
3528 to->si_addr_lsb = from->si_addr_lsb;
3529 break;
3530 case SIL_FAULT_BNDERR:
3531 to->si_addr = compat_ptr(from->si_addr);
3532 to->si_lower = compat_ptr(from->si_lower);
3533 to->si_upper = compat_ptr(from->si_upper);
3534 break;
3535 case SIL_FAULT_PKUERR:
3536 to->si_addr = compat_ptr(from->si_addr);
3537 to->si_pkey = from->si_pkey;
3538 break;
3539 case SIL_FAULT_PERF_EVENT:
3540 to->si_addr = compat_ptr(from->si_addr);
3541 to->si_perf_data = from->si_perf_data;
3542 to->si_perf_type = from->si_perf_type;
3543 to->si_perf_flags = from->si_perf_flags;
3544 break;
3545 case SIL_CHLD:
3546 to->si_pid = from->si_pid;
3547 to->si_uid = from->si_uid;
3548 to->si_status = from->si_status;
3549#ifdef CONFIG_X86_X32_ABI
3550 if (in_x32_syscall()) {
3551 to->si_utime = from->_sifields._sigchld_x32._utime;
3552 to->si_stime = from->_sifields._sigchld_x32._stime;
3553 } else
3554#endif
3555 {
3556 to->si_utime = from->si_utime;
3557 to->si_stime = from->si_stime;
3558 }
3559 break;
3560 case SIL_RT:
3561 to->si_pid = from->si_pid;
3562 to->si_uid = from->si_uid;
3563 to->si_int = from->si_int;
3564 break;
3565 case SIL_SYS:
3566 to->si_call_addr = compat_ptr(from->si_call_addr);
3567 to->si_syscall = from->si_syscall;
3568 to->si_arch = from->si_arch;
3569 break;
3570 }
3571 return 0;
3572}
3573
3574static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3575 const struct compat_siginfo __user *ufrom)
3576{
3577 struct compat_siginfo from;
3578
3579 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3580 return -EFAULT;
3581
3582 from.si_signo = signo;
3583 return post_copy_siginfo_from_user32(to, &from);
3584}
3585
3586int copy_siginfo_from_user32(struct kernel_siginfo *to,
3587 const struct compat_siginfo __user *ufrom)
3588{
3589 struct compat_siginfo from;
3590
3591 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3592 return -EFAULT;
3593
3594 return post_copy_siginfo_from_user32(to, &from);
3595}
3596#endif /* CONFIG_COMPAT */
3597
3598/**
3599 * do_sigtimedwait - wait for queued signals specified in @which
3600 * @which: queued signals to wait for
3601 * @info: if non-null, the signal's siginfo is returned here
3602 * @ts: upper bound on process time suspension
3603 */
3604static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3605 const struct timespec64 *ts)
3606{
3607 ktime_t *to = NULL, timeout = KTIME_MAX;
3608 struct task_struct *tsk = current;
3609 sigset_t mask = *which;
3610 enum pid_type type;
3611 int sig, ret = 0;
3612
3613 if (ts) {
3614 if (!timespec64_valid(ts))
3615 return -EINVAL;
3616 timeout = timespec64_to_ktime(*ts);
3617 to = &timeout;
3618 }
3619
3620 /*
3621 * Invert the set of allowed signals to get those we want to block.
3622 */
3623 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3624 signotset(&mask);
3625
3626 spin_lock_irq(&tsk->sighand->siglock);
3627 sig = dequeue_signal(tsk, &mask, info, &type);
3628 if (!sig && timeout) {
3629 /*
3630 * None ready, temporarily unblock those we're interested
3631 * while we are sleeping in so that we'll be awakened when
3632 * they arrive. Unblocking is always fine, we can avoid
3633 * set_current_blocked().
3634 */
3635 tsk->real_blocked = tsk->blocked;
3636 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3637 recalc_sigpending();
3638 spin_unlock_irq(&tsk->sighand->siglock);
3639
3640 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3641 ret = schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3642 HRTIMER_MODE_REL);
3643 spin_lock_irq(&tsk->sighand->siglock);
3644 __set_task_blocked(tsk, &tsk->real_blocked);
3645 sigemptyset(&tsk->real_blocked);
3646 sig = dequeue_signal(tsk, &mask, info, &type);
3647 }
3648 spin_unlock_irq(&tsk->sighand->siglock);
3649
3650 if (sig)
3651 return sig;
3652 return ret ? -EINTR : -EAGAIN;
3653}
3654
3655/**
3656 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3657 * in @uthese
3658 * @uthese: queued signals to wait for
3659 * @uinfo: if non-null, the signal's siginfo is returned here
3660 * @uts: upper bound on process time suspension
3661 * @sigsetsize: size of sigset_t type
3662 */
3663SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3664 siginfo_t __user *, uinfo,
3665 const struct __kernel_timespec __user *, uts,
3666 size_t, sigsetsize)
3667{
3668 sigset_t these;
3669 struct timespec64 ts;
3670 kernel_siginfo_t info;
3671 int ret;
3672
3673 /* XXX: Don't preclude handling different sized sigset_t's. */
3674 if (sigsetsize != sizeof(sigset_t))
3675 return -EINVAL;
3676
3677 if (copy_from_user(&these, uthese, sizeof(these)))
3678 return -EFAULT;
3679
3680 if (uts) {
3681 if (get_timespec64(&ts, uts))
3682 return -EFAULT;
3683 }
3684
3685 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3686
3687 if (ret > 0 && uinfo) {
3688 if (copy_siginfo_to_user(uinfo, &info))
3689 ret = -EFAULT;
3690 }
3691
3692 return ret;
3693}
3694
3695#ifdef CONFIG_COMPAT_32BIT_TIME
3696SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3697 siginfo_t __user *, uinfo,
3698 const struct old_timespec32 __user *, uts,
3699 size_t, sigsetsize)
3700{
3701 sigset_t these;
3702 struct timespec64 ts;
3703 kernel_siginfo_t info;
3704 int ret;
3705
3706 if (sigsetsize != sizeof(sigset_t))
3707 return -EINVAL;
3708
3709 if (copy_from_user(&these, uthese, sizeof(these)))
3710 return -EFAULT;
3711
3712 if (uts) {
3713 if (get_old_timespec32(&ts, uts))
3714 return -EFAULT;
3715 }
3716
3717 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3718
3719 if (ret > 0 && uinfo) {
3720 if (copy_siginfo_to_user(uinfo, &info))
3721 ret = -EFAULT;
3722 }
3723
3724 return ret;
3725}
3726#endif
3727
3728#ifdef CONFIG_COMPAT
3729COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3730 struct compat_siginfo __user *, uinfo,
3731 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3732{
3733 sigset_t s;
3734 struct timespec64 t;
3735 kernel_siginfo_t info;
3736 long ret;
3737
3738 if (sigsetsize != sizeof(sigset_t))
3739 return -EINVAL;
3740
3741 if (get_compat_sigset(&s, uthese))
3742 return -EFAULT;
3743
3744 if (uts) {
3745 if (get_timespec64(&t, uts))
3746 return -EFAULT;
3747 }
3748
3749 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3750
3751 if (ret > 0 && uinfo) {
3752 if (copy_siginfo_to_user32(uinfo, &info))
3753 ret = -EFAULT;
3754 }
3755
3756 return ret;
3757}
3758
3759#ifdef CONFIG_COMPAT_32BIT_TIME
3760COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3761 struct compat_siginfo __user *, uinfo,
3762 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3763{
3764 sigset_t s;
3765 struct timespec64 t;
3766 kernel_siginfo_t info;
3767 long ret;
3768
3769 if (sigsetsize != sizeof(sigset_t))
3770 return -EINVAL;
3771
3772 if (get_compat_sigset(&s, uthese))
3773 return -EFAULT;
3774
3775 if (uts) {
3776 if (get_old_timespec32(&t, uts))
3777 return -EFAULT;
3778 }
3779
3780 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3781
3782 if (ret > 0 && uinfo) {
3783 if (copy_siginfo_to_user32(uinfo, &info))
3784 ret = -EFAULT;
3785 }
3786
3787 return ret;
3788}
3789#endif
3790#endif
3791
3792static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3793{
3794 clear_siginfo(info);
3795 info->si_signo = sig;
3796 info->si_errno = 0;
3797 info->si_code = SI_USER;
3798 info->si_pid = task_tgid_vnr(current);
3799 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3800}
3801
3802/**
3803 * sys_kill - send a signal to a process
3804 * @pid: the PID of the process
3805 * @sig: signal to be sent
3806 */
3807SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3808{
3809 struct kernel_siginfo info;
3810
3811 prepare_kill_siginfo(sig, &info);
3812
3813 return kill_something_info(sig, &info, pid);
3814}
3815
3816/*
3817 * Verify that the signaler and signalee either are in the same pid namespace
3818 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3819 * namespace.
3820 */
3821static bool access_pidfd_pidns(struct pid *pid)
3822{
3823 struct pid_namespace *active = task_active_pid_ns(current);
3824 struct pid_namespace *p = ns_of_pid(pid);
3825
3826 for (;;) {
3827 if (!p)
3828 return false;
3829 if (p == active)
3830 break;
3831 p = p->parent;
3832 }
3833
3834 return true;
3835}
3836
3837static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3838 siginfo_t __user *info)
3839{
3840#ifdef CONFIG_COMPAT
3841 /*
3842 * Avoid hooking up compat syscalls and instead handle necessary
3843 * conversions here. Note, this is a stop-gap measure and should not be
3844 * considered a generic solution.
3845 */
3846 if (in_compat_syscall())
3847 return copy_siginfo_from_user32(
3848 kinfo, (struct compat_siginfo __user *)info);
3849#endif
3850 return copy_siginfo_from_user(kinfo, info);
3851}
3852
3853static struct pid *pidfd_to_pid(const struct file *file)
3854{
3855 struct pid *pid;
3856
3857 pid = pidfd_pid(file);
3858 if (!IS_ERR(pid))
3859 return pid;
3860
3861 return tgid_pidfd_to_pid(file);
3862}
3863
3864/**
3865 * sys_pidfd_send_signal - Signal a process through a pidfd
3866 * @pidfd: file descriptor of the process
3867 * @sig: signal to send
3868 * @info: signal info
3869 * @flags: future flags
3870 *
3871 * The syscall currently only signals via PIDTYPE_PID which covers
3872 * kill(<positive-pid>, <signal>. It does not signal threads or process
3873 * groups.
3874 * In order to extend the syscall to threads and process groups the @flags
3875 * argument should be used. In essence, the @flags argument will determine
3876 * what is signaled and not the file descriptor itself. Put in other words,
3877 * grouping is a property of the flags argument not a property of the file
3878 * descriptor.
3879 *
3880 * Return: 0 on success, negative errno on failure
3881 */
3882SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3883 siginfo_t __user *, info, unsigned int, flags)
3884{
3885 int ret;
3886 struct fd f;
3887 struct pid *pid;
3888 kernel_siginfo_t kinfo;
3889
3890 /* Enforce flags be set to 0 until we add an extension. */
3891 if (flags)
3892 return -EINVAL;
3893
3894 f = fdget(pidfd);
3895 if (!f.file)
3896 return -EBADF;
3897
3898 /* Is this a pidfd? */
3899 pid = pidfd_to_pid(f.file);
3900 if (IS_ERR(pid)) {
3901 ret = PTR_ERR(pid);
3902 goto err;
3903 }
3904
3905 ret = -EINVAL;
3906 if (!access_pidfd_pidns(pid))
3907 goto err;
3908
3909 if (info) {
3910 ret = copy_siginfo_from_user_any(&kinfo, info);
3911 if (unlikely(ret))
3912 goto err;
3913
3914 ret = -EINVAL;
3915 if (unlikely(sig != kinfo.si_signo))
3916 goto err;
3917
3918 /* Only allow sending arbitrary signals to yourself. */
3919 ret = -EPERM;
3920 if ((task_pid(current) != pid) &&
3921 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3922 goto err;
3923 } else {
3924 prepare_kill_siginfo(sig, &kinfo);
3925 }
3926
3927 ret = kill_pid_info(sig, &kinfo, pid);
3928
3929err:
3930 fdput(f);
3931 return ret;
3932}
3933
3934static int
3935do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3936{
3937 struct task_struct *p;
3938 int error = -ESRCH;
3939
3940 rcu_read_lock();
3941 p = find_task_by_vpid(pid);
3942 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3943 error = check_kill_permission(sig, info, p);
3944 /*
3945 * The null signal is a permissions and process existence
3946 * probe. No signal is actually delivered.
3947 */
3948 if (!error && sig) {
3949 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3950 /*
3951 * If lock_task_sighand() failed we pretend the task
3952 * dies after receiving the signal. The window is tiny,
3953 * and the signal is private anyway.
3954 */
3955 if (unlikely(error == -ESRCH))
3956 error = 0;
3957 }
3958 }
3959 rcu_read_unlock();
3960
3961 return error;
3962}
3963
3964static int do_tkill(pid_t tgid, pid_t pid, int sig)
3965{
3966 struct kernel_siginfo info;
3967
3968 clear_siginfo(&info);
3969 info.si_signo = sig;
3970 info.si_errno = 0;
3971 info.si_code = SI_TKILL;
3972 info.si_pid = task_tgid_vnr(current);
3973 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3974
3975 return do_send_specific(tgid, pid, sig, &info);
3976}
3977
3978/**
3979 * sys_tgkill - send signal to one specific thread
3980 * @tgid: the thread group ID of the thread
3981 * @pid: the PID of the thread
3982 * @sig: signal to be sent
3983 *
3984 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3985 * exists but it's not belonging to the target process anymore. This
3986 * method solves the problem of threads exiting and PIDs getting reused.
3987 */
3988SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3989{
3990 /* This is only valid for single tasks */
3991 if (pid <= 0 || tgid <= 0)
3992 return -EINVAL;
3993
3994 return do_tkill(tgid, pid, sig);
3995}
3996
3997/**
3998 * sys_tkill - send signal to one specific task
3999 * @pid: the PID of the task
4000 * @sig: signal to be sent
4001 *
4002 * Send a signal to only one task, even if it's a CLONE_THREAD task.
4003 */
4004SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4005{
4006 /* This is only valid for single tasks */
4007 if (pid <= 0)
4008 return -EINVAL;
4009
4010 return do_tkill(0, pid, sig);
4011}
4012
4013static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4014{
4015 /* Not even root can pretend to send signals from the kernel.
4016 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4017 */
4018 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4019 (task_pid_vnr(current) != pid))
4020 return -EPERM;
4021
4022 /* POSIX.1b doesn't mention process groups. */
4023 return kill_proc_info(sig, info, pid);
4024}
4025
4026/**
4027 * sys_rt_sigqueueinfo - send signal information to a signal
4028 * @pid: the PID of the thread
4029 * @sig: signal to be sent
4030 * @uinfo: signal info to be sent
4031 */
4032SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4033 siginfo_t __user *, uinfo)
4034{
4035 kernel_siginfo_t info;
4036 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4037 if (unlikely(ret))
4038 return ret;
4039 return do_rt_sigqueueinfo(pid, sig, &info);
4040}
4041
4042#ifdef CONFIG_COMPAT
4043COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4044 compat_pid_t, pid,
4045 int, sig,
4046 struct compat_siginfo __user *, uinfo)
4047{
4048 kernel_siginfo_t info;
4049 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4050 if (unlikely(ret))
4051 return ret;
4052 return do_rt_sigqueueinfo(pid, sig, &info);
4053}
4054#endif
4055
4056static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4057{
4058 /* This is only valid for single tasks */
4059 if (pid <= 0 || tgid <= 0)
4060 return -EINVAL;
4061
4062 /* Not even root can pretend to send signals from the kernel.
4063 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4064 */
4065 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4066 (task_pid_vnr(current) != pid))
4067 return -EPERM;
4068
4069 return do_send_specific(tgid, pid, sig, info);
4070}
4071
4072SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4073 siginfo_t __user *, uinfo)
4074{
4075 kernel_siginfo_t info;
4076 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4077 if (unlikely(ret))
4078 return ret;
4079 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4080}
4081
4082#ifdef CONFIG_COMPAT
4083COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4084 compat_pid_t, tgid,
4085 compat_pid_t, pid,
4086 int, sig,
4087 struct compat_siginfo __user *, uinfo)
4088{
4089 kernel_siginfo_t info;
4090 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4091 if (unlikely(ret))
4092 return ret;
4093 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4094}
4095#endif
4096
4097/*
4098 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4099 */
4100void kernel_sigaction(int sig, __sighandler_t action)
4101{
4102 spin_lock_irq(¤t->sighand->siglock);
4103 current->sighand->action[sig - 1].sa.sa_handler = action;
4104 if (action == SIG_IGN) {
4105 sigset_t mask;
4106
4107 sigemptyset(&mask);
4108 sigaddset(&mask, sig);
4109
4110 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4111 flush_sigqueue_mask(&mask, ¤t->pending);
4112 recalc_sigpending();
4113 }
4114 spin_unlock_irq(¤t->sighand->siglock);
4115}
4116EXPORT_SYMBOL(kernel_sigaction);
4117
4118void __weak sigaction_compat_abi(struct k_sigaction *act,
4119 struct k_sigaction *oact)
4120{
4121}
4122
4123int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4124{
4125 struct task_struct *p = current, *t;
4126 struct k_sigaction *k;
4127 sigset_t mask;
4128
4129 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4130 return -EINVAL;
4131
4132 k = &p->sighand->action[sig-1];
4133
4134 spin_lock_irq(&p->sighand->siglock);
4135 if (k->sa.sa_flags & SA_IMMUTABLE) {
4136 spin_unlock_irq(&p->sighand->siglock);
4137 return -EINVAL;
4138 }
4139 if (oact)
4140 *oact = *k;
4141
4142 /*
4143 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4144 * e.g. by having an architecture use the bit in their uapi.
4145 */
4146 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4147
4148 /*
4149 * Clear unknown flag bits in order to allow userspace to detect missing
4150 * support for flag bits and to allow the kernel to use non-uapi bits
4151 * internally.
4152 */
4153 if (act)
4154 act->sa.sa_flags &= UAPI_SA_FLAGS;
4155 if (oact)
4156 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4157
4158 sigaction_compat_abi(act, oact);
4159
4160 if (act) {
4161 sigdelsetmask(&act->sa.sa_mask,
4162 sigmask(SIGKILL) | sigmask(SIGSTOP));
4163 *k = *act;
4164 /*
4165 * POSIX 3.3.1.3:
4166 * "Setting a signal action to SIG_IGN for a signal that is
4167 * pending shall cause the pending signal to be discarded,
4168 * whether or not it is blocked."
4169 *
4170 * "Setting a signal action to SIG_DFL for a signal that is
4171 * pending and whose default action is to ignore the signal
4172 * (for example, SIGCHLD), shall cause the pending signal to
4173 * be discarded, whether or not it is blocked"
4174 */
4175 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4176 sigemptyset(&mask);
4177 sigaddset(&mask, sig);
4178 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4179 for_each_thread(p, t)
4180 flush_sigqueue_mask(&mask, &t->pending);
4181 }
4182 }
4183
4184 spin_unlock_irq(&p->sighand->siglock);
4185 return 0;
4186}
4187
4188#ifdef CONFIG_DYNAMIC_SIGFRAME
4189static inline void sigaltstack_lock(void)
4190 __acquires(¤t->sighand->siglock)
4191{
4192 spin_lock_irq(¤t->sighand->siglock);
4193}
4194
4195static inline void sigaltstack_unlock(void)
4196 __releases(¤t->sighand->siglock)
4197{
4198 spin_unlock_irq(¤t->sighand->siglock);
4199}
4200#else
4201static inline void sigaltstack_lock(void) { }
4202static inline void sigaltstack_unlock(void) { }
4203#endif
4204
4205static int
4206do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4207 size_t min_ss_size)
4208{
4209 struct task_struct *t = current;
4210 int ret = 0;
4211
4212 if (oss) {
4213 memset(oss, 0, sizeof(stack_t));
4214 oss->ss_sp = (void __user *) t->sas_ss_sp;
4215 oss->ss_size = t->sas_ss_size;
4216 oss->ss_flags = sas_ss_flags(sp) |
4217 (current->sas_ss_flags & SS_FLAG_BITS);
4218 }
4219
4220 if (ss) {
4221 void __user *ss_sp = ss->ss_sp;
4222 size_t ss_size = ss->ss_size;
4223 unsigned ss_flags = ss->ss_flags;
4224 int ss_mode;
4225
4226 if (unlikely(on_sig_stack(sp)))
4227 return -EPERM;
4228
4229 ss_mode = ss_flags & ~SS_FLAG_BITS;
4230 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4231 ss_mode != 0))
4232 return -EINVAL;
4233
4234 /*
4235 * Return before taking any locks if no actual
4236 * sigaltstack changes were requested.
4237 */
4238 if (t->sas_ss_sp == (unsigned long)ss_sp &&
4239 t->sas_ss_size == ss_size &&
4240 t->sas_ss_flags == ss_flags)
4241 return 0;
4242
4243 sigaltstack_lock();
4244 if (ss_mode == SS_DISABLE) {
4245 ss_size = 0;
4246 ss_sp = NULL;
4247 } else {
4248 if (unlikely(ss_size < min_ss_size))
4249 ret = -ENOMEM;
4250 if (!sigaltstack_size_valid(ss_size))
4251 ret = -ENOMEM;
4252 }
4253 if (!ret) {
4254 t->sas_ss_sp = (unsigned long) ss_sp;
4255 t->sas_ss_size = ss_size;
4256 t->sas_ss_flags = ss_flags;
4257 }
4258 sigaltstack_unlock();
4259 }
4260 return ret;
4261}
4262
4263SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4264{
4265 stack_t new, old;
4266 int err;
4267 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4268 return -EFAULT;
4269 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4270 current_user_stack_pointer(),
4271 MINSIGSTKSZ);
4272 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4273 err = -EFAULT;
4274 return err;
4275}
4276
4277int restore_altstack(const stack_t __user *uss)
4278{
4279 stack_t new;
4280 if (copy_from_user(&new, uss, sizeof(stack_t)))
4281 return -EFAULT;
4282 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4283 MINSIGSTKSZ);
4284 /* squash all but EFAULT for now */
4285 return 0;
4286}
4287
4288int __save_altstack(stack_t __user *uss, unsigned long sp)
4289{
4290 struct task_struct *t = current;
4291 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4292 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4293 __put_user(t->sas_ss_size, &uss->ss_size);
4294 return err;
4295}
4296
4297#ifdef CONFIG_COMPAT
4298static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4299 compat_stack_t __user *uoss_ptr)
4300{
4301 stack_t uss, uoss;
4302 int ret;
4303
4304 if (uss_ptr) {
4305 compat_stack_t uss32;
4306 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4307 return -EFAULT;
4308 uss.ss_sp = compat_ptr(uss32.ss_sp);
4309 uss.ss_flags = uss32.ss_flags;
4310 uss.ss_size = uss32.ss_size;
4311 }
4312 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4313 compat_user_stack_pointer(),
4314 COMPAT_MINSIGSTKSZ);
4315 if (ret >= 0 && uoss_ptr) {
4316 compat_stack_t old;
4317 memset(&old, 0, sizeof(old));
4318 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4319 old.ss_flags = uoss.ss_flags;
4320 old.ss_size = uoss.ss_size;
4321 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4322 ret = -EFAULT;
4323 }
4324 return ret;
4325}
4326
4327COMPAT_SYSCALL_DEFINE2(sigaltstack,
4328 const compat_stack_t __user *, uss_ptr,
4329 compat_stack_t __user *, uoss_ptr)
4330{
4331 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4332}
4333
4334int compat_restore_altstack(const compat_stack_t __user *uss)
4335{
4336 int err = do_compat_sigaltstack(uss, NULL);
4337 /* squash all but -EFAULT for now */
4338 return err == -EFAULT ? err : 0;
4339}
4340
4341int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4342{
4343 int err;
4344 struct task_struct *t = current;
4345 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4346 &uss->ss_sp) |
4347 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4348 __put_user(t->sas_ss_size, &uss->ss_size);
4349 return err;
4350}
4351#endif
4352
4353#ifdef __ARCH_WANT_SYS_SIGPENDING
4354
4355/**
4356 * sys_sigpending - examine pending signals
4357 * @uset: where mask of pending signal is returned
4358 */
4359SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4360{
4361 sigset_t set;
4362
4363 if (sizeof(old_sigset_t) > sizeof(*uset))
4364 return -EINVAL;
4365
4366 do_sigpending(&set);
4367
4368 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4369 return -EFAULT;
4370
4371 return 0;
4372}
4373
4374#ifdef CONFIG_COMPAT
4375COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4376{
4377 sigset_t set;
4378
4379 do_sigpending(&set);
4380
4381 return put_user(set.sig[0], set32);
4382}
4383#endif
4384
4385#endif
4386
4387#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4388/**
4389 * sys_sigprocmask - examine and change blocked signals
4390 * @how: whether to add, remove, or set signals
4391 * @nset: signals to add or remove (if non-null)
4392 * @oset: previous value of signal mask if non-null
4393 *
4394 * Some platforms have their own version with special arguments;
4395 * others support only sys_rt_sigprocmask.
4396 */
4397
4398SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4399 old_sigset_t __user *, oset)
4400{
4401 old_sigset_t old_set, new_set;
4402 sigset_t new_blocked;
4403
4404 old_set = current->blocked.sig[0];
4405
4406 if (nset) {
4407 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4408 return -EFAULT;
4409
4410 new_blocked = current->blocked;
4411
4412 switch (how) {
4413 case SIG_BLOCK:
4414 sigaddsetmask(&new_blocked, new_set);
4415 break;
4416 case SIG_UNBLOCK:
4417 sigdelsetmask(&new_blocked, new_set);
4418 break;
4419 case SIG_SETMASK:
4420 new_blocked.sig[0] = new_set;
4421 break;
4422 default:
4423 return -EINVAL;
4424 }
4425
4426 set_current_blocked(&new_blocked);
4427 }
4428
4429 if (oset) {
4430 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4431 return -EFAULT;
4432 }
4433
4434 return 0;
4435}
4436#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4437
4438#ifndef CONFIG_ODD_RT_SIGACTION
4439/**
4440 * sys_rt_sigaction - alter an action taken by a process
4441 * @sig: signal to be sent
4442 * @act: new sigaction
4443 * @oact: used to save the previous sigaction
4444 * @sigsetsize: size of sigset_t type
4445 */
4446SYSCALL_DEFINE4(rt_sigaction, int, sig,
4447 const struct sigaction __user *, act,
4448 struct sigaction __user *, oact,
4449 size_t, sigsetsize)
4450{
4451 struct k_sigaction new_sa, old_sa;
4452 int ret;
4453
4454 /* XXX: Don't preclude handling different sized sigset_t's. */
4455 if (sigsetsize != sizeof(sigset_t))
4456 return -EINVAL;
4457
4458 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4459 return -EFAULT;
4460
4461 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4462 if (ret)
4463 return ret;
4464
4465 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4466 return -EFAULT;
4467
4468 return 0;
4469}
4470#ifdef CONFIG_COMPAT
4471COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4472 const struct compat_sigaction __user *, act,
4473 struct compat_sigaction __user *, oact,
4474 compat_size_t, sigsetsize)
4475{
4476 struct k_sigaction new_ka, old_ka;
4477#ifdef __ARCH_HAS_SA_RESTORER
4478 compat_uptr_t restorer;
4479#endif
4480 int ret;
4481
4482 /* XXX: Don't preclude handling different sized sigset_t's. */
4483 if (sigsetsize != sizeof(compat_sigset_t))
4484 return -EINVAL;
4485
4486 if (act) {
4487 compat_uptr_t handler;
4488 ret = get_user(handler, &act->sa_handler);
4489 new_ka.sa.sa_handler = compat_ptr(handler);
4490#ifdef __ARCH_HAS_SA_RESTORER
4491 ret |= get_user(restorer, &act->sa_restorer);
4492 new_ka.sa.sa_restorer = compat_ptr(restorer);
4493#endif
4494 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4495 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4496 if (ret)
4497 return -EFAULT;
4498 }
4499
4500 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4501 if (!ret && oact) {
4502 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4503 &oact->sa_handler);
4504 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4505 sizeof(oact->sa_mask));
4506 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4507#ifdef __ARCH_HAS_SA_RESTORER
4508 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4509 &oact->sa_restorer);
4510#endif
4511 }
4512 return ret;
4513}
4514#endif
4515#endif /* !CONFIG_ODD_RT_SIGACTION */
4516
4517#ifdef CONFIG_OLD_SIGACTION
4518SYSCALL_DEFINE3(sigaction, int, sig,
4519 const struct old_sigaction __user *, act,
4520 struct old_sigaction __user *, oact)
4521{
4522 struct k_sigaction new_ka, old_ka;
4523 int ret;
4524
4525 if (act) {
4526 old_sigset_t mask;
4527 if (!access_ok(act, sizeof(*act)) ||
4528 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4529 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4530 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4531 __get_user(mask, &act->sa_mask))
4532 return -EFAULT;
4533#ifdef __ARCH_HAS_KA_RESTORER
4534 new_ka.ka_restorer = NULL;
4535#endif
4536 siginitset(&new_ka.sa.sa_mask, mask);
4537 }
4538
4539 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4540
4541 if (!ret && oact) {
4542 if (!access_ok(oact, sizeof(*oact)) ||
4543 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4544 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4545 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4546 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4547 return -EFAULT;
4548 }
4549
4550 return ret;
4551}
4552#endif
4553#ifdef CONFIG_COMPAT_OLD_SIGACTION
4554COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4555 const struct compat_old_sigaction __user *, act,
4556 struct compat_old_sigaction __user *, oact)
4557{
4558 struct k_sigaction new_ka, old_ka;
4559 int ret;
4560 compat_old_sigset_t mask;
4561 compat_uptr_t handler, restorer;
4562
4563 if (act) {
4564 if (!access_ok(act, sizeof(*act)) ||
4565 __get_user(handler, &act->sa_handler) ||
4566 __get_user(restorer, &act->sa_restorer) ||
4567 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4568 __get_user(mask, &act->sa_mask))
4569 return -EFAULT;
4570
4571#ifdef __ARCH_HAS_KA_RESTORER
4572 new_ka.ka_restorer = NULL;
4573#endif
4574 new_ka.sa.sa_handler = compat_ptr(handler);
4575 new_ka.sa.sa_restorer = compat_ptr(restorer);
4576 siginitset(&new_ka.sa.sa_mask, mask);
4577 }
4578
4579 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4580
4581 if (!ret && oact) {
4582 if (!access_ok(oact, sizeof(*oact)) ||
4583 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4584 &oact->sa_handler) ||
4585 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4586 &oact->sa_restorer) ||
4587 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4588 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4589 return -EFAULT;
4590 }
4591 return ret;
4592}
4593#endif
4594
4595#ifdef CONFIG_SGETMASK_SYSCALL
4596
4597/*
4598 * For backwards compatibility. Functionality superseded by sigprocmask.
4599 */
4600SYSCALL_DEFINE0(sgetmask)
4601{
4602 /* SMP safe */
4603 return current->blocked.sig[0];
4604}
4605
4606SYSCALL_DEFINE1(ssetmask, int, newmask)
4607{
4608 int old = current->blocked.sig[0];
4609 sigset_t newset;
4610
4611 siginitset(&newset, newmask);
4612 set_current_blocked(&newset);
4613
4614 return old;
4615}
4616#endif /* CONFIG_SGETMASK_SYSCALL */
4617
4618#ifdef __ARCH_WANT_SYS_SIGNAL
4619/*
4620 * For backwards compatibility. Functionality superseded by sigaction.
4621 */
4622SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4623{
4624 struct k_sigaction new_sa, old_sa;
4625 int ret;
4626
4627 new_sa.sa.sa_handler = handler;
4628 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4629 sigemptyset(&new_sa.sa.sa_mask);
4630
4631 ret = do_sigaction(sig, &new_sa, &old_sa);
4632
4633 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4634}
4635#endif /* __ARCH_WANT_SYS_SIGNAL */
4636
4637#ifdef __ARCH_WANT_SYS_PAUSE
4638
4639SYSCALL_DEFINE0(pause)
4640{
4641 while (!signal_pending(current)) {
4642 __set_current_state(TASK_INTERRUPTIBLE);
4643 schedule();
4644 }
4645 return -ERESTARTNOHAND;
4646}
4647
4648#endif
4649
4650static int sigsuspend(sigset_t *set)
4651{
4652 current->saved_sigmask = current->blocked;
4653 set_current_blocked(set);
4654
4655 while (!signal_pending(current)) {
4656 __set_current_state(TASK_INTERRUPTIBLE);
4657 schedule();
4658 }
4659 set_restore_sigmask();
4660 return -ERESTARTNOHAND;
4661}
4662
4663/**
4664 * sys_rt_sigsuspend - replace the signal mask for a value with the
4665 * @unewset value until a signal is received
4666 * @unewset: new signal mask value
4667 * @sigsetsize: size of sigset_t type
4668 */
4669SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4670{
4671 sigset_t newset;
4672
4673 /* XXX: Don't preclude handling different sized sigset_t's. */
4674 if (sigsetsize != sizeof(sigset_t))
4675 return -EINVAL;
4676
4677 if (copy_from_user(&newset, unewset, sizeof(newset)))
4678 return -EFAULT;
4679 return sigsuspend(&newset);
4680}
4681
4682#ifdef CONFIG_COMPAT
4683COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4684{
4685 sigset_t newset;
4686
4687 /* XXX: Don't preclude handling different sized sigset_t's. */
4688 if (sigsetsize != sizeof(sigset_t))
4689 return -EINVAL;
4690
4691 if (get_compat_sigset(&newset, unewset))
4692 return -EFAULT;
4693 return sigsuspend(&newset);
4694}
4695#endif
4696
4697#ifdef CONFIG_OLD_SIGSUSPEND
4698SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4699{
4700 sigset_t blocked;
4701 siginitset(&blocked, mask);
4702 return sigsuspend(&blocked);
4703}
4704#endif
4705#ifdef CONFIG_OLD_SIGSUSPEND3
4706SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4707{
4708 sigset_t blocked;
4709 siginitset(&blocked, mask);
4710 return sigsuspend(&blocked);
4711}
4712#endif
4713
4714__weak const char *arch_vma_name(struct vm_area_struct *vma)
4715{
4716 return NULL;
4717}
4718
4719static inline void siginfo_buildtime_checks(void)
4720{
4721 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4722
4723 /* Verify the offsets in the two siginfos match */
4724#define CHECK_OFFSET(field) \
4725 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4726
4727 /* kill */
4728 CHECK_OFFSET(si_pid);
4729 CHECK_OFFSET(si_uid);
4730
4731 /* timer */
4732 CHECK_OFFSET(si_tid);
4733 CHECK_OFFSET(si_overrun);
4734 CHECK_OFFSET(si_value);
4735
4736 /* rt */
4737 CHECK_OFFSET(si_pid);
4738 CHECK_OFFSET(si_uid);
4739 CHECK_OFFSET(si_value);
4740
4741 /* sigchld */
4742 CHECK_OFFSET(si_pid);
4743 CHECK_OFFSET(si_uid);
4744 CHECK_OFFSET(si_status);
4745 CHECK_OFFSET(si_utime);
4746 CHECK_OFFSET(si_stime);
4747
4748 /* sigfault */
4749 CHECK_OFFSET(si_addr);
4750 CHECK_OFFSET(si_trapno);
4751 CHECK_OFFSET(si_addr_lsb);
4752 CHECK_OFFSET(si_lower);
4753 CHECK_OFFSET(si_upper);
4754 CHECK_OFFSET(si_pkey);
4755 CHECK_OFFSET(si_perf_data);
4756 CHECK_OFFSET(si_perf_type);
4757 CHECK_OFFSET(si_perf_flags);
4758
4759 /* sigpoll */
4760 CHECK_OFFSET(si_band);
4761 CHECK_OFFSET(si_fd);
4762
4763 /* sigsys */
4764 CHECK_OFFSET(si_call_addr);
4765 CHECK_OFFSET(si_syscall);
4766 CHECK_OFFSET(si_arch);
4767#undef CHECK_OFFSET
4768
4769 /* usb asyncio */
4770 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4771 offsetof(struct siginfo, si_addr));
4772 if (sizeof(int) == sizeof(void __user *)) {
4773 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4774 sizeof(void __user *));
4775 } else {
4776 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4777 sizeof_field(struct siginfo, si_uid)) !=
4778 sizeof(void __user *));
4779 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4780 offsetof(struct siginfo, si_uid));
4781 }
4782#ifdef CONFIG_COMPAT
4783 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4784 offsetof(struct compat_siginfo, si_addr));
4785 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4786 sizeof(compat_uptr_t));
4787 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4788 sizeof_field(struct siginfo, si_pid));
4789#endif
4790}
4791
4792#if defined(CONFIG_SYSCTL)
4793static struct ctl_table signal_debug_table[] = {
4794#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4795 {
4796 .procname = "exception-trace",
4797 .data = &show_unhandled_signals,
4798 .maxlen = sizeof(int),
4799 .mode = 0644,
4800 .proc_handler = proc_dointvec
4801 },
4802#endif
4803 { }
4804};
4805
4806static int __init init_signal_sysctls(void)
4807{
4808 register_sysctl_init("debug", signal_debug_table);
4809 return 0;
4810}
4811early_initcall(init_signal_sysctls);
4812#endif /* CONFIG_SYSCTL */
4813
4814void __init signals_init(void)
4815{
4816 siginfo_buildtime_checks();
4817
4818 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4819}
4820
4821#ifdef CONFIG_KGDB_KDB
4822#include <linux/kdb.h>
4823/*
4824 * kdb_send_sig - Allows kdb to send signals without exposing
4825 * signal internals. This function checks if the required locks are
4826 * available before calling the main signal code, to avoid kdb
4827 * deadlocks.
4828 */
4829void kdb_send_sig(struct task_struct *t, int sig)
4830{
4831 static struct task_struct *kdb_prev_t;
4832 int new_t, ret;
4833 if (!spin_trylock(&t->sighand->siglock)) {
4834 kdb_printf("Can't do kill command now.\n"
4835 "The sigmask lock is held somewhere else in "
4836 "kernel, try again later\n");
4837 return;
4838 }
4839 new_t = kdb_prev_t != t;
4840 kdb_prev_t = t;
4841 if (!task_is_running(t) && new_t) {
4842 spin_unlock(&t->sighand->siglock);
4843 kdb_printf("Process is not RUNNING, sending a signal from "
4844 "kdb risks deadlock\n"
4845 "on the run queue locks. "
4846 "The signal has _not_ been sent.\n"
4847 "Reissue the kill command if you want to risk "
4848 "the deadlock.\n");
4849 return;
4850 }
4851 ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4852 spin_unlock(&t->sighand->siglock);
4853 if (ret)
4854 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4855 sig, t->pid);
4856 else
4857 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4858}
4859#endif /* CONFIG_KGDB_KDB */