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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/module.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/security.h>
21#include <linux/syscalls.h>
22#include <linux/ptrace.h>
23#include <linux/signal.h>
24#include <linux/signalfd.h>
25#include <linux/ratelimit.h>
26#include <linux/tracehook.h>
27#include <linux/capability.h>
28#include <linux/freezer.h>
29#include <linux/pid_namespace.h>
30#include <linux/nsproxy.h>
31#define CREATE_TRACE_POINTS
32#include <trace/events/signal.h>
33
34#include <asm/param.h>
35#include <asm/uaccess.h>
36#include <asm/unistd.h>
37#include <asm/siginfo.h>
38#include "audit.h" /* audit_signal_info() */
39
40/*
41 * SLAB caches for signal bits.
42 */
43
44static struct kmem_cache *sigqueue_cachep;
45
46int print_fatal_signals __read_mostly;
47
48static void __user *sig_handler(struct task_struct *t, int sig)
49{
50 return t->sighand->action[sig - 1].sa.sa_handler;
51}
52
53static int sig_handler_ignored(void __user *handler, int sig)
54{
55 /* Is it explicitly or implicitly ignored? */
56 return handler == SIG_IGN ||
57 (handler == SIG_DFL && sig_kernel_ignore(sig));
58}
59
60static int sig_task_ignored(struct task_struct *t, int sig,
61 int from_ancestor_ns)
62{
63 void __user *handler;
64
65 handler = sig_handler(t, sig);
66
67 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
68 handler == SIG_DFL && !from_ancestor_ns)
69 return 1;
70
71 return sig_handler_ignored(handler, sig);
72}
73
74static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
75{
76 /*
77 * Blocked signals are never ignored, since the
78 * signal handler may change by the time it is
79 * unblocked.
80 */
81 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
82 return 0;
83
84 if (!sig_task_ignored(t, sig, from_ancestor_ns))
85 return 0;
86
87 /*
88 * Tracers may want to know about even ignored signals.
89 */
90 return !t->ptrace;
91}
92
93/*
94 * Re-calculate pending state from the set of locally pending
95 * signals, globally pending signals, and blocked signals.
96 */
97static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
98{
99 unsigned long ready;
100 long i;
101
102 switch (_NSIG_WORDS) {
103 default:
104 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
105 ready |= signal->sig[i] &~ blocked->sig[i];
106 break;
107
108 case 4: ready = signal->sig[3] &~ blocked->sig[3];
109 ready |= signal->sig[2] &~ blocked->sig[2];
110 ready |= signal->sig[1] &~ blocked->sig[1];
111 ready |= signal->sig[0] &~ blocked->sig[0];
112 break;
113
114 case 2: ready = signal->sig[1] &~ blocked->sig[1];
115 ready |= signal->sig[0] &~ blocked->sig[0];
116 break;
117
118 case 1: ready = signal->sig[0] &~ blocked->sig[0];
119 }
120 return ready != 0;
121}
122
123#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
124
125static int recalc_sigpending_tsk(struct task_struct *t)
126{
127 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
128 PENDING(&t->pending, &t->blocked) ||
129 PENDING(&t->signal->shared_pending, &t->blocked)) {
130 set_tsk_thread_flag(t, TIF_SIGPENDING);
131 return 1;
132 }
133 /*
134 * We must never clear the flag in another thread, or in current
135 * when it's possible the current syscall is returning -ERESTART*.
136 * So we don't clear it here, and only callers who know they should do.
137 */
138 return 0;
139}
140
141/*
142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
143 * This is superfluous when called on current, the wakeup is a harmless no-op.
144 */
145void recalc_sigpending_and_wake(struct task_struct *t)
146{
147 if (recalc_sigpending_tsk(t))
148 signal_wake_up(t, 0);
149}
150
151void recalc_sigpending(void)
152{
153 if (!recalc_sigpending_tsk(current) && !freezing(current))
154 clear_thread_flag(TIF_SIGPENDING);
155
156}
157
158/* Given the mask, find the first available signal that should be serviced. */
159
160#define SYNCHRONOUS_MASK \
161 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
162 sigmask(SIGTRAP) | sigmask(SIGFPE))
163
164int next_signal(struct sigpending *pending, sigset_t *mask)
165{
166 unsigned long i, *s, *m, x;
167 int sig = 0;
168
169 s = pending->signal.sig;
170 m = mask->sig;
171
172 /*
173 * Handle the first word specially: it contains the
174 * synchronous signals that need to be dequeued first.
175 */
176 x = *s &~ *m;
177 if (x) {
178 if (x & SYNCHRONOUS_MASK)
179 x &= SYNCHRONOUS_MASK;
180 sig = ffz(~x) + 1;
181 return sig;
182 }
183
184 switch (_NSIG_WORDS) {
185 default:
186 for (i = 1; i < _NSIG_WORDS; ++i) {
187 x = *++s &~ *++m;
188 if (!x)
189 continue;
190 sig = ffz(~x) + i*_NSIG_BPW + 1;
191 break;
192 }
193 break;
194
195 case 2:
196 x = s[1] &~ m[1];
197 if (!x)
198 break;
199 sig = ffz(~x) + _NSIG_BPW + 1;
200 break;
201
202 case 1:
203 /* Nothing to do */
204 break;
205 }
206
207 return sig;
208}
209
210static inline void print_dropped_signal(int sig)
211{
212 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
213
214 if (!print_fatal_signals)
215 return;
216
217 if (!__ratelimit(&ratelimit_state))
218 return;
219
220 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
221 current->comm, current->pid, sig);
222}
223
224/**
225 * task_set_jobctl_pending - set jobctl pending bits
226 * @task: target task
227 * @mask: pending bits to set
228 *
229 * Clear @mask from @task->jobctl. @mask must be subset of
230 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
231 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
232 * cleared. If @task is already being killed or exiting, this function
233 * becomes noop.
234 *
235 * CONTEXT:
236 * Must be called with @task->sighand->siglock held.
237 *
238 * RETURNS:
239 * %true if @mask is set, %false if made noop because @task was dying.
240 */
241bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
242{
243 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
244 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
245 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
246
247 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
248 return false;
249
250 if (mask & JOBCTL_STOP_SIGMASK)
251 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
252
253 task->jobctl |= mask;
254 return true;
255}
256
257/**
258 * task_clear_jobctl_trapping - clear jobctl trapping bit
259 * @task: target task
260 *
261 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
262 * Clear it and wake up the ptracer. Note that we don't need any further
263 * locking. @task->siglock guarantees that @task->parent points to the
264 * ptracer.
265 *
266 * CONTEXT:
267 * Must be called with @task->sighand->siglock held.
268 */
269void task_clear_jobctl_trapping(struct task_struct *task)
270{
271 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
272 task->jobctl &= ~JOBCTL_TRAPPING;
273 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
274 }
275}
276
277/**
278 * task_clear_jobctl_pending - clear jobctl pending bits
279 * @task: target task
280 * @mask: pending bits to clear
281 *
282 * Clear @mask from @task->jobctl. @mask must be subset of
283 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
284 * STOP bits are cleared together.
285 *
286 * If clearing of @mask leaves no stop or trap pending, this function calls
287 * task_clear_jobctl_trapping().
288 *
289 * CONTEXT:
290 * Must be called with @task->sighand->siglock held.
291 */
292void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
293{
294 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
295
296 if (mask & JOBCTL_STOP_PENDING)
297 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
298
299 task->jobctl &= ~mask;
300
301 if (!(task->jobctl & JOBCTL_PENDING_MASK))
302 task_clear_jobctl_trapping(task);
303}
304
305/**
306 * task_participate_group_stop - participate in a group stop
307 * @task: task participating in a group stop
308 *
309 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
310 * Group stop states are cleared and the group stop count is consumed if
311 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
312 * stop, the appropriate %SIGNAL_* flags are set.
313 *
314 * CONTEXT:
315 * Must be called with @task->sighand->siglock held.
316 *
317 * RETURNS:
318 * %true if group stop completion should be notified to the parent, %false
319 * otherwise.
320 */
321static bool task_participate_group_stop(struct task_struct *task)
322{
323 struct signal_struct *sig = task->signal;
324 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
325
326 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
327
328 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
329
330 if (!consume)
331 return false;
332
333 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
334 sig->group_stop_count--;
335
336 /*
337 * Tell the caller to notify completion iff we are entering into a
338 * fresh group stop. Read comment in do_signal_stop() for details.
339 */
340 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
341 sig->flags = SIGNAL_STOP_STOPPED;
342 return true;
343 }
344 return false;
345}
346
347/*
348 * allocate a new signal queue record
349 * - this may be called without locks if and only if t == current, otherwise an
350 * appropriate lock must be held to stop the target task from exiting
351 */
352static struct sigqueue *
353__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
354{
355 struct sigqueue *q = NULL;
356 struct user_struct *user;
357
358 /*
359 * Protect access to @t credentials. This can go away when all
360 * callers hold rcu read lock.
361 */
362 rcu_read_lock();
363 user = get_uid(__task_cred(t)->user);
364 atomic_inc(&user->sigpending);
365 rcu_read_unlock();
366
367 if (override_rlimit ||
368 atomic_read(&user->sigpending) <=
369 task_rlimit(t, RLIMIT_SIGPENDING)) {
370 q = kmem_cache_alloc(sigqueue_cachep, flags);
371 } else {
372 print_dropped_signal(sig);
373 }
374
375 if (unlikely(q == NULL)) {
376 atomic_dec(&user->sigpending);
377 free_uid(user);
378 } else {
379 INIT_LIST_HEAD(&q->list);
380 q->flags = 0;
381 q->user = user;
382 }
383
384 return q;
385}
386
387static void __sigqueue_free(struct sigqueue *q)
388{
389 if (q->flags & SIGQUEUE_PREALLOC)
390 return;
391 atomic_dec(&q->user->sigpending);
392 free_uid(q->user);
393 kmem_cache_free(sigqueue_cachep, q);
394}
395
396void flush_sigqueue(struct sigpending *queue)
397{
398 struct sigqueue *q;
399
400 sigemptyset(&queue->signal);
401 while (!list_empty(&queue->list)) {
402 q = list_entry(queue->list.next, struct sigqueue , list);
403 list_del_init(&q->list);
404 __sigqueue_free(q);
405 }
406}
407
408/*
409 * Flush all pending signals for a task.
410 */
411void __flush_signals(struct task_struct *t)
412{
413 clear_tsk_thread_flag(t, TIF_SIGPENDING);
414 flush_sigqueue(&t->pending);
415 flush_sigqueue(&t->signal->shared_pending);
416}
417
418void flush_signals(struct task_struct *t)
419{
420 unsigned long flags;
421
422 spin_lock_irqsave(&t->sighand->siglock, flags);
423 __flush_signals(t);
424 spin_unlock_irqrestore(&t->sighand->siglock, flags);
425}
426
427static void __flush_itimer_signals(struct sigpending *pending)
428{
429 sigset_t signal, retain;
430 struct sigqueue *q, *n;
431
432 signal = pending->signal;
433 sigemptyset(&retain);
434
435 list_for_each_entry_safe(q, n, &pending->list, list) {
436 int sig = q->info.si_signo;
437
438 if (likely(q->info.si_code != SI_TIMER)) {
439 sigaddset(&retain, sig);
440 } else {
441 sigdelset(&signal, sig);
442 list_del_init(&q->list);
443 __sigqueue_free(q);
444 }
445 }
446
447 sigorsets(&pending->signal, &signal, &retain);
448}
449
450void flush_itimer_signals(void)
451{
452 struct task_struct *tsk = current;
453 unsigned long flags;
454
455 spin_lock_irqsave(&tsk->sighand->siglock, flags);
456 __flush_itimer_signals(&tsk->pending);
457 __flush_itimer_signals(&tsk->signal->shared_pending);
458 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
459}
460
461void ignore_signals(struct task_struct *t)
462{
463 int i;
464
465 for (i = 0; i < _NSIG; ++i)
466 t->sighand->action[i].sa.sa_handler = SIG_IGN;
467
468 flush_signals(t);
469}
470
471/*
472 * Flush all handlers for a task.
473 */
474
475void
476flush_signal_handlers(struct task_struct *t, int force_default)
477{
478 int i;
479 struct k_sigaction *ka = &t->sighand->action[0];
480 for (i = _NSIG ; i != 0 ; i--) {
481 if (force_default || ka->sa.sa_handler != SIG_IGN)
482 ka->sa.sa_handler = SIG_DFL;
483 ka->sa.sa_flags = 0;
484 sigemptyset(&ka->sa.sa_mask);
485 ka++;
486 }
487}
488
489int unhandled_signal(struct task_struct *tsk, int sig)
490{
491 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
492 if (is_global_init(tsk))
493 return 1;
494 if (handler != SIG_IGN && handler != SIG_DFL)
495 return 0;
496 /* if ptraced, let the tracer determine */
497 return !tsk->ptrace;
498}
499
500/*
501 * Notify the system that a driver wants to block all signals for this
502 * process, and wants to be notified if any signals at all were to be
503 * sent/acted upon. If the notifier routine returns non-zero, then the
504 * signal will be acted upon after all. If the notifier routine returns 0,
505 * then then signal will be blocked. Only one block per process is
506 * allowed. priv is a pointer to private data that the notifier routine
507 * can use to determine if the signal should be blocked or not.
508 */
509void
510block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
511{
512 unsigned long flags;
513
514 spin_lock_irqsave(¤t->sighand->siglock, flags);
515 current->notifier_mask = mask;
516 current->notifier_data = priv;
517 current->notifier = notifier;
518 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
519}
520
521/* Notify the system that blocking has ended. */
522
523void
524unblock_all_signals(void)
525{
526 unsigned long flags;
527
528 spin_lock_irqsave(¤t->sighand->siglock, flags);
529 current->notifier = NULL;
530 current->notifier_data = NULL;
531 recalc_sigpending();
532 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
533}
534
535static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
536{
537 struct sigqueue *q, *first = NULL;
538
539 /*
540 * Collect the siginfo appropriate to this signal. Check if
541 * there is another siginfo for the same signal.
542 */
543 list_for_each_entry(q, &list->list, list) {
544 if (q->info.si_signo == sig) {
545 if (first)
546 goto still_pending;
547 first = q;
548 }
549 }
550
551 sigdelset(&list->signal, sig);
552
553 if (first) {
554still_pending:
555 list_del_init(&first->list);
556 copy_siginfo(info, &first->info);
557 __sigqueue_free(first);
558 } else {
559 /*
560 * Ok, it wasn't in the queue. This must be
561 * a fast-pathed signal or we must have been
562 * out of queue space. So zero out the info.
563 */
564 info->si_signo = sig;
565 info->si_errno = 0;
566 info->si_code = SI_USER;
567 info->si_pid = 0;
568 info->si_uid = 0;
569 }
570}
571
572static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
573 siginfo_t *info)
574{
575 int sig = next_signal(pending, mask);
576
577 if (sig) {
578 if (current->notifier) {
579 if (sigismember(current->notifier_mask, sig)) {
580 if (!(current->notifier)(current->notifier_data)) {
581 clear_thread_flag(TIF_SIGPENDING);
582 return 0;
583 }
584 }
585 }
586
587 collect_signal(sig, pending, info);
588 }
589
590 return sig;
591}
592
593/*
594 * Dequeue a signal and return the element to the caller, which is
595 * expected to free it.
596 *
597 * All callers have to hold the siglock.
598 */
599int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
600{
601 int signr;
602
603 /* We only dequeue private signals from ourselves, we don't let
604 * signalfd steal them
605 */
606 signr = __dequeue_signal(&tsk->pending, mask, info);
607 if (!signr) {
608 signr = __dequeue_signal(&tsk->signal->shared_pending,
609 mask, info);
610 /*
611 * itimer signal ?
612 *
613 * itimers are process shared and we restart periodic
614 * itimers in the signal delivery path to prevent DoS
615 * attacks in the high resolution timer case. This is
616 * compliant with the old way of self-restarting
617 * itimers, as the SIGALRM is a legacy signal and only
618 * queued once. Changing the restart behaviour to
619 * restart the timer in the signal dequeue path is
620 * reducing the timer noise on heavy loaded !highres
621 * systems too.
622 */
623 if (unlikely(signr == SIGALRM)) {
624 struct hrtimer *tmr = &tsk->signal->real_timer;
625
626 if (!hrtimer_is_queued(tmr) &&
627 tsk->signal->it_real_incr.tv64 != 0) {
628 hrtimer_forward(tmr, tmr->base->get_time(),
629 tsk->signal->it_real_incr);
630 hrtimer_restart(tmr);
631 }
632 }
633 }
634
635 recalc_sigpending();
636 if (!signr)
637 return 0;
638
639 if (unlikely(sig_kernel_stop(signr))) {
640 /*
641 * Set a marker that we have dequeued a stop signal. Our
642 * caller might release the siglock and then the pending
643 * stop signal it is about to process is no longer in the
644 * pending bitmasks, but must still be cleared by a SIGCONT
645 * (and overruled by a SIGKILL). So those cases clear this
646 * shared flag after we've set it. Note that this flag may
647 * remain set after the signal we return is ignored or
648 * handled. That doesn't matter because its only purpose
649 * is to alert stop-signal processing code when another
650 * processor has come along and cleared the flag.
651 */
652 current->jobctl |= JOBCTL_STOP_DEQUEUED;
653 }
654 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
655 /*
656 * Release the siglock to ensure proper locking order
657 * of timer locks outside of siglocks. Note, we leave
658 * irqs disabled here, since the posix-timers code is
659 * about to disable them again anyway.
660 */
661 spin_unlock(&tsk->sighand->siglock);
662 do_schedule_next_timer(info);
663 spin_lock(&tsk->sighand->siglock);
664 }
665 return signr;
666}
667
668/*
669 * Tell a process that it has a new active signal..
670 *
671 * NOTE! we rely on the previous spin_lock to
672 * lock interrupts for us! We can only be called with
673 * "siglock" held, and the local interrupt must
674 * have been disabled when that got acquired!
675 *
676 * No need to set need_resched since signal event passing
677 * goes through ->blocked
678 */
679void signal_wake_up(struct task_struct *t, int resume)
680{
681 unsigned int mask;
682
683 set_tsk_thread_flag(t, TIF_SIGPENDING);
684
685 /*
686 * For SIGKILL, we want to wake it up in the stopped/traced/killable
687 * case. We don't check t->state here because there is a race with it
688 * executing another processor and just now entering stopped state.
689 * By using wake_up_state, we ensure the process will wake up and
690 * handle its death signal.
691 */
692 mask = TASK_INTERRUPTIBLE;
693 if (resume)
694 mask |= TASK_WAKEKILL;
695 if (!wake_up_state(t, mask))
696 kick_process(t);
697}
698
699/*
700 * Remove signals in mask from the pending set and queue.
701 * Returns 1 if any signals were found.
702 *
703 * All callers must be holding the siglock.
704 *
705 * This version takes a sigset mask and looks at all signals,
706 * not just those in the first mask word.
707 */
708static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
709{
710 struct sigqueue *q, *n;
711 sigset_t m;
712
713 sigandsets(&m, mask, &s->signal);
714 if (sigisemptyset(&m))
715 return 0;
716
717 sigandnsets(&s->signal, &s->signal, mask);
718 list_for_each_entry_safe(q, n, &s->list, list) {
719 if (sigismember(mask, q->info.si_signo)) {
720 list_del_init(&q->list);
721 __sigqueue_free(q);
722 }
723 }
724 return 1;
725}
726/*
727 * Remove signals in mask from the pending set and queue.
728 * Returns 1 if any signals were found.
729 *
730 * All callers must be holding the siglock.
731 */
732static int rm_from_queue(unsigned long mask, struct sigpending *s)
733{
734 struct sigqueue *q, *n;
735
736 if (!sigtestsetmask(&s->signal, mask))
737 return 0;
738
739 sigdelsetmask(&s->signal, mask);
740 list_for_each_entry_safe(q, n, &s->list, list) {
741 if (q->info.si_signo < SIGRTMIN &&
742 (mask & sigmask(q->info.si_signo))) {
743 list_del_init(&q->list);
744 __sigqueue_free(q);
745 }
746 }
747 return 1;
748}
749
750static inline int is_si_special(const struct siginfo *info)
751{
752 return info <= SEND_SIG_FORCED;
753}
754
755static inline bool si_fromuser(const struct siginfo *info)
756{
757 return info == SEND_SIG_NOINFO ||
758 (!is_si_special(info) && SI_FROMUSER(info));
759}
760
761/*
762 * called with RCU read lock from check_kill_permission()
763 */
764static int kill_ok_by_cred(struct task_struct *t)
765{
766 const struct cred *cred = current_cred();
767 const struct cred *tcred = __task_cred(t);
768
769 if (cred->user->user_ns == tcred->user->user_ns &&
770 (cred->euid == tcred->suid ||
771 cred->euid == tcred->uid ||
772 cred->uid == tcred->suid ||
773 cred->uid == tcred->uid))
774 return 1;
775
776 if (ns_capable(tcred->user->user_ns, CAP_KILL))
777 return 1;
778
779 return 0;
780}
781
782/*
783 * Bad permissions for sending the signal
784 * - the caller must hold the RCU read lock
785 */
786static int check_kill_permission(int sig, struct siginfo *info,
787 struct task_struct *t)
788{
789 struct pid *sid;
790 int error;
791
792 if (!valid_signal(sig))
793 return -EINVAL;
794
795 if (!si_fromuser(info))
796 return 0;
797
798 error = audit_signal_info(sig, t); /* Let audit system see the signal */
799 if (error)
800 return error;
801
802 if (!same_thread_group(current, t) &&
803 !kill_ok_by_cred(t)) {
804 switch (sig) {
805 case SIGCONT:
806 sid = task_session(t);
807 /*
808 * We don't return the error if sid == NULL. The
809 * task was unhashed, the caller must notice this.
810 */
811 if (!sid || sid == task_session(current))
812 break;
813 default:
814 return -EPERM;
815 }
816 }
817
818 return security_task_kill(t, info, sig, 0);
819}
820
821/**
822 * ptrace_trap_notify - schedule trap to notify ptracer
823 * @t: tracee wanting to notify tracer
824 *
825 * This function schedules sticky ptrace trap which is cleared on the next
826 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
827 * ptracer.
828 *
829 * If @t is running, STOP trap will be taken. If trapped for STOP and
830 * ptracer is listening for events, tracee is woken up so that it can
831 * re-trap for the new event. If trapped otherwise, STOP trap will be
832 * eventually taken without returning to userland after the existing traps
833 * are finished by PTRACE_CONT.
834 *
835 * CONTEXT:
836 * Must be called with @task->sighand->siglock held.
837 */
838static void ptrace_trap_notify(struct task_struct *t)
839{
840 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
841 assert_spin_locked(&t->sighand->siglock);
842
843 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
844 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
845}
846
847/*
848 * Handle magic process-wide effects of stop/continue signals. Unlike
849 * the signal actions, these happen immediately at signal-generation
850 * time regardless of blocking, ignoring, or handling. This does the
851 * actual continuing for SIGCONT, but not the actual stopping for stop
852 * signals. The process stop is done as a signal action for SIG_DFL.
853 *
854 * Returns true if the signal should be actually delivered, otherwise
855 * it should be dropped.
856 */
857static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
858{
859 struct signal_struct *signal = p->signal;
860 struct task_struct *t;
861
862 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
863 /*
864 * The process is in the middle of dying, nothing to do.
865 */
866 } else if (sig_kernel_stop(sig)) {
867 /*
868 * This is a stop signal. Remove SIGCONT from all queues.
869 */
870 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
871 t = p;
872 do {
873 rm_from_queue(sigmask(SIGCONT), &t->pending);
874 } while_each_thread(p, t);
875 } else if (sig == SIGCONT) {
876 unsigned int why;
877 /*
878 * Remove all stop signals from all queues, wake all threads.
879 */
880 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
881 t = p;
882 do {
883 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
884 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
885 if (likely(!(t->ptrace & PT_SEIZED)))
886 wake_up_state(t, __TASK_STOPPED);
887 else
888 ptrace_trap_notify(t);
889 } while_each_thread(p, t);
890
891 /*
892 * Notify the parent with CLD_CONTINUED if we were stopped.
893 *
894 * If we were in the middle of a group stop, we pretend it
895 * was already finished, and then continued. Since SIGCHLD
896 * doesn't queue we report only CLD_STOPPED, as if the next
897 * CLD_CONTINUED was dropped.
898 */
899 why = 0;
900 if (signal->flags & SIGNAL_STOP_STOPPED)
901 why |= SIGNAL_CLD_CONTINUED;
902 else if (signal->group_stop_count)
903 why |= SIGNAL_CLD_STOPPED;
904
905 if (why) {
906 /*
907 * The first thread which returns from do_signal_stop()
908 * will take ->siglock, notice SIGNAL_CLD_MASK, and
909 * notify its parent. See get_signal_to_deliver().
910 */
911 signal->flags = why | SIGNAL_STOP_CONTINUED;
912 signal->group_stop_count = 0;
913 signal->group_exit_code = 0;
914 }
915 }
916
917 return !sig_ignored(p, sig, from_ancestor_ns);
918}
919
920/*
921 * Test if P wants to take SIG. After we've checked all threads with this,
922 * it's equivalent to finding no threads not blocking SIG. Any threads not
923 * blocking SIG were ruled out because they are not running and already
924 * have pending signals. Such threads will dequeue from the shared queue
925 * as soon as they're available, so putting the signal on the shared queue
926 * will be equivalent to sending it to one such thread.
927 */
928static inline int wants_signal(int sig, struct task_struct *p)
929{
930 if (sigismember(&p->blocked, sig))
931 return 0;
932 if (p->flags & PF_EXITING)
933 return 0;
934 if (sig == SIGKILL)
935 return 1;
936 if (task_is_stopped_or_traced(p))
937 return 0;
938 return task_curr(p) || !signal_pending(p);
939}
940
941static void complete_signal(int sig, struct task_struct *p, int group)
942{
943 struct signal_struct *signal = p->signal;
944 struct task_struct *t;
945
946 /*
947 * Now find a thread we can wake up to take the signal off the queue.
948 *
949 * If the main thread wants the signal, it gets first crack.
950 * Probably the least surprising to the average bear.
951 */
952 if (wants_signal(sig, p))
953 t = p;
954 else if (!group || thread_group_empty(p))
955 /*
956 * There is just one thread and it does not need to be woken.
957 * It will dequeue unblocked signals before it runs again.
958 */
959 return;
960 else {
961 /*
962 * Otherwise try to find a suitable thread.
963 */
964 t = signal->curr_target;
965 while (!wants_signal(sig, t)) {
966 t = next_thread(t);
967 if (t == signal->curr_target)
968 /*
969 * No thread needs to be woken.
970 * Any eligible threads will see
971 * the signal in the queue soon.
972 */
973 return;
974 }
975 signal->curr_target = t;
976 }
977
978 /*
979 * Found a killable thread. If the signal will be fatal,
980 * then start taking the whole group down immediately.
981 */
982 if (sig_fatal(p, sig) &&
983 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
984 !sigismember(&t->real_blocked, sig) &&
985 (sig == SIGKILL || !t->ptrace)) {
986 /*
987 * This signal will be fatal to the whole group.
988 */
989 if (!sig_kernel_coredump(sig)) {
990 /*
991 * Start a group exit and wake everybody up.
992 * This way we don't have other threads
993 * running and doing things after a slower
994 * thread has the fatal signal pending.
995 */
996 signal->flags = SIGNAL_GROUP_EXIT;
997 signal->group_exit_code = sig;
998 signal->group_stop_count = 0;
999 t = p;
1000 do {
1001 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1002 sigaddset(&t->pending.signal, SIGKILL);
1003 signal_wake_up(t, 1);
1004 } while_each_thread(p, t);
1005 return;
1006 }
1007 }
1008
1009 /*
1010 * The signal is already in the shared-pending queue.
1011 * Tell the chosen thread to wake up and dequeue it.
1012 */
1013 signal_wake_up(t, sig == SIGKILL);
1014 return;
1015}
1016
1017static inline int legacy_queue(struct sigpending *signals, int sig)
1018{
1019 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1020}
1021
1022static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1023 int group, int from_ancestor_ns)
1024{
1025 struct sigpending *pending;
1026 struct sigqueue *q;
1027 int override_rlimit;
1028
1029 trace_signal_generate(sig, info, t);
1030
1031 assert_spin_locked(&t->sighand->siglock);
1032
1033 if (!prepare_signal(sig, t, from_ancestor_ns))
1034 return 0;
1035
1036 pending = group ? &t->signal->shared_pending : &t->pending;
1037 /*
1038 * Short-circuit ignored signals and support queuing
1039 * exactly one non-rt signal, so that we can get more
1040 * detailed information about the cause of the signal.
1041 */
1042 if (legacy_queue(pending, sig))
1043 return 0;
1044 /*
1045 * fast-pathed signals for kernel-internal things like SIGSTOP
1046 * or SIGKILL.
1047 */
1048 if (info == SEND_SIG_FORCED)
1049 goto out_set;
1050
1051 /*
1052 * Real-time signals must be queued if sent by sigqueue, or
1053 * some other real-time mechanism. It is implementation
1054 * defined whether kill() does so. We attempt to do so, on
1055 * the principle of least surprise, but since kill is not
1056 * allowed to fail with EAGAIN when low on memory we just
1057 * make sure at least one signal gets delivered and don't
1058 * pass on the info struct.
1059 */
1060 if (sig < SIGRTMIN)
1061 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1062 else
1063 override_rlimit = 0;
1064
1065 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1066 override_rlimit);
1067 if (q) {
1068 list_add_tail(&q->list, &pending->list);
1069 switch ((unsigned long) info) {
1070 case (unsigned long) SEND_SIG_NOINFO:
1071 q->info.si_signo = sig;
1072 q->info.si_errno = 0;
1073 q->info.si_code = SI_USER;
1074 q->info.si_pid = task_tgid_nr_ns(current,
1075 task_active_pid_ns(t));
1076 q->info.si_uid = current_uid();
1077 break;
1078 case (unsigned long) SEND_SIG_PRIV:
1079 q->info.si_signo = sig;
1080 q->info.si_errno = 0;
1081 q->info.si_code = SI_KERNEL;
1082 q->info.si_pid = 0;
1083 q->info.si_uid = 0;
1084 break;
1085 default:
1086 copy_siginfo(&q->info, info);
1087 if (from_ancestor_ns)
1088 q->info.si_pid = 0;
1089 break;
1090 }
1091 } else if (!is_si_special(info)) {
1092 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1093 /*
1094 * Queue overflow, abort. We may abort if the
1095 * signal was rt and sent by user using something
1096 * other than kill().
1097 */
1098 trace_signal_overflow_fail(sig, group, info);
1099 return -EAGAIN;
1100 } else {
1101 /*
1102 * This is a silent loss of information. We still
1103 * send the signal, but the *info bits are lost.
1104 */
1105 trace_signal_lose_info(sig, group, info);
1106 }
1107 }
1108
1109out_set:
1110 signalfd_notify(t, sig);
1111 sigaddset(&pending->signal, sig);
1112 complete_signal(sig, t, group);
1113 return 0;
1114}
1115
1116static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1117 int group)
1118{
1119 int from_ancestor_ns = 0;
1120
1121#ifdef CONFIG_PID_NS
1122 from_ancestor_ns = si_fromuser(info) &&
1123 !task_pid_nr_ns(current, task_active_pid_ns(t));
1124#endif
1125
1126 return __send_signal(sig, info, t, group, from_ancestor_ns);
1127}
1128
1129static void print_fatal_signal(struct pt_regs *regs, int signr)
1130{
1131 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1132 current->comm, task_pid_nr(current), signr);
1133
1134#if defined(__i386__) && !defined(__arch_um__)
1135 printk("code at %08lx: ", regs->ip);
1136 {
1137 int i;
1138 for (i = 0; i < 16; i++) {
1139 unsigned char insn;
1140
1141 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1142 break;
1143 printk("%02x ", insn);
1144 }
1145 }
1146#endif
1147 printk("\n");
1148 preempt_disable();
1149 show_regs(regs);
1150 preempt_enable();
1151}
1152
1153static int __init setup_print_fatal_signals(char *str)
1154{
1155 get_option (&str, &print_fatal_signals);
1156
1157 return 1;
1158}
1159
1160__setup("print-fatal-signals=", setup_print_fatal_signals);
1161
1162int
1163__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1164{
1165 return send_signal(sig, info, p, 1);
1166}
1167
1168static int
1169specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1170{
1171 return send_signal(sig, info, t, 0);
1172}
1173
1174int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1175 bool group)
1176{
1177 unsigned long flags;
1178 int ret = -ESRCH;
1179
1180 if (lock_task_sighand(p, &flags)) {
1181 ret = send_signal(sig, info, p, group);
1182 unlock_task_sighand(p, &flags);
1183 }
1184
1185 return ret;
1186}
1187
1188/*
1189 * Force a signal that the process can't ignore: if necessary
1190 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1191 *
1192 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1193 * since we do not want to have a signal handler that was blocked
1194 * be invoked when user space had explicitly blocked it.
1195 *
1196 * We don't want to have recursive SIGSEGV's etc, for example,
1197 * that is why we also clear SIGNAL_UNKILLABLE.
1198 */
1199int
1200force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1201{
1202 unsigned long int flags;
1203 int ret, blocked, ignored;
1204 struct k_sigaction *action;
1205
1206 spin_lock_irqsave(&t->sighand->siglock, flags);
1207 action = &t->sighand->action[sig-1];
1208 ignored = action->sa.sa_handler == SIG_IGN;
1209 blocked = sigismember(&t->blocked, sig);
1210 if (blocked || ignored) {
1211 action->sa.sa_handler = SIG_DFL;
1212 if (blocked) {
1213 sigdelset(&t->blocked, sig);
1214 recalc_sigpending_and_wake(t);
1215 }
1216 }
1217 if (action->sa.sa_handler == SIG_DFL)
1218 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1219 ret = specific_send_sig_info(sig, info, t);
1220 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1221
1222 return ret;
1223}
1224
1225/*
1226 * Nuke all other threads in the group.
1227 */
1228int zap_other_threads(struct task_struct *p)
1229{
1230 struct task_struct *t = p;
1231 int count = 0;
1232
1233 p->signal->group_stop_count = 0;
1234
1235 while_each_thread(p, t) {
1236 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1237 count++;
1238
1239 /* Don't bother with already dead threads */
1240 if (t->exit_state)
1241 continue;
1242 sigaddset(&t->pending.signal, SIGKILL);
1243 signal_wake_up(t, 1);
1244 }
1245
1246 return count;
1247}
1248
1249struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1250 unsigned long *flags)
1251{
1252 struct sighand_struct *sighand;
1253
1254 for (;;) {
1255 local_irq_save(*flags);
1256 rcu_read_lock();
1257 sighand = rcu_dereference(tsk->sighand);
1258 if (unlikely(sighand == NULL)) {
1259 rcu_read_unlock();
1260 local_irq_restore(*flags);
1261 break;
1262 }
1263
1264 spin_lock(&sighand->siglock);
1265 if (likely(sighand == tsk->sighand)) {
1266 rcu_read_unlock();
1267 break;
1268 }
1269 spin_unlock(&sighand->siglock);
1270 rcu_read_unlock();
1271 local_irq_restore(*flags);
1272 }
1273
1274 return sighand;
1275}
1276
1277/*
1278 * send signal info to all the members of a group
1279 */
1280int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1281{
1282 int ret;
1283
1284 rcu_read_lock();
1285 ret = check_kill_permission(sig, info, p);
1286 rcu_read_unlock();
1287
1288 if (!ret && sig)
1289 ret = do_send_sig_info(sig, info, p, true);
1290
1291 return ret;
1292}
1293
1294/*
1295 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1296 * control characters do (^C, ^Z etc)
1297 * - the caller must hold at least a readlock on tasklist_lock
1298 */
1299int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1300{
1301 struct task_struct *p = NULL;
1302 int retval, success;
1303
1304 success = 0;
1305 retval = -ESRCH;
1306 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1307 int err = group_send_sig_info(sig, info, p);
1308 success |= !err;
1309 retval = err;
1310 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1311 return success ? 0 : retval;
1312}
1313
1314int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1315{
1316 int error = -ESRCH;
1317 struct task_struct *p;
1318
1319 rcu_read_lock();
1320retry:
1321 p = pid_task(pid, PIDTYPE_PID);
1322 if (p) {
1323 error = group_send_sig_info(sig, info, p);
1324 if (unlikely(error == -ESRCH))
1325 /*
1326 * The task was unhashed in between, try again.
1327 * If it is dead, pid_task() will return NULL,
1328 * if we race with de_thread() it will find the
1329 * new leader.
1330 */
1331 goto retry;
1332 }
1333 rcu_read_unlock();
1334
1335 return error;
1336}
1337
1338int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1339{
1340 int error;
1341 rcu_read_lock();
1342 error = kill_pid_info(sig, info, find_vpid(pid));
1343 rcu_read_unlock();
1344 return error;
1345}
1346
1347/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1348int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1349 uid_t uid, uid_t euid, u32 secid)
1350{
1351 int ret = -EINVAL;
1352 struct task_struct *p;
1353 const struct cred *pcred;
1354 unsigned long flags;
1355
1356 if (!valid_signal(sig))
1357 return ret;
1358
1359 rcu_read_lock();
1360 p = pid_task(pid, PIDTYPE_PID);
1361 if (!p) {
1362 ret = -ESRCH;
1363 goto out_unlock;
1364 }
1365 pcred = __task_cred(p);
1366 if (si_fromuser(info) &&
1367 euid != pcred->suid && euid != pcred->uid &&
1368 uid != pcred->suid && uid != pcred->uid) {
1369 ret = -EPERM;
1370 goto out_unlock;
1371 }
1372 ret = security_task_kill(p, info, sig, secid);
1373 if (ret)
1374 goto out_unlock;
1375
1376 if (sig) {
1377 if (lock_task_sighand(p, &flags)) {
1378 ret = __send_signal(sig, info, p, 1, 0);
1379 unlock_task_sighand(p, &flags);
1380 } else
1381 ret = -ESRCH;
1382 }
1383out_unlock:
1384 rcu_read_unlock();
1385 return ret;
1386}
1387EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1388
1389/*
1390 * kill_something_info() interprets pid in interesting ways just like kill(2).
1391 *
1392 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1393 * is probably wrong. Should make it like BSD or SYSV.
1394 */
1395
1396static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1397{
1398 int ret;
1399
1400 if (pid > 0) {
1401 rcu_read_lock();
1402 ret = kill_pid_info(sig, info, find_vpid(pid));
1403 rcu_read_unlock();
1404 return ret;
1405 }
1406
1407 read_lock(&tasklist_lock);
1408 if (pid != -1) {
1409 ret = __kill_pgrp_info(sig, info,
1410 pid ? find_vpid(-pid) : task_pgrp(current));
1411 } else {
1412 int retval = 0, count = 0;
1413 struct task_struct * p;
1414
1415 for_each_process(p) {
1416 if (task_pid_vnr(p) > 1 &&
1417 !same_thread_group(p, current)) {
1418 int err = group_send_sig_info(sig, info, p);
1419 ++count;
1420 if (err != -EPERM)
1421 retval = err;
1422 }
1423 }
1424 ret = count ? retval : -ESRCH;
1425 }
1426 read_unlock(&tasklist_lock);
1427
1428 return ret;
1429}
1430
1431/*
1432 * These are for backward compatibility with the rest of the kernel source.
1433 */
1434
1435int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1436{
1437 /*
1438 * Make sure legacy kernel users don't send in bad values
1439 * (normal paths check this in check_kill_permission).
1440 */
1441 if (!valid_signal(sig))
1442 return -EINVAL;
1443
1444 return do_send_sig_info(sig, info, p, false);
1445}
1446
1447#define __si_special(priv) \
1448 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1449
1450int
1451send_sig(int sig, struct task_struct *p, int priv)
1452{
1453 return send_sig_info(sig, __si_special(priv), p);
1454}
1455
1456void
1457force_sig(int sig, struct task_struct *p)
1458{
1459 force_sig_info(sig, SEND_SIG_PRIV, p);
1460}
1461
1462/*
1463 * When things go south during signal handling, we
1464 * will force a SIGSEGV. And if the signal that caused
1465 * the problem was already a SIGSEGV, we'll want to
1466 * make sure we don't even try to deliver the signal..
1467 */
1468int
1469force_sigsegv(int sig, struct task_struct *p)
1470{
1471 if (sig == SIGSEGV) {
1472 unsigned long flags;
1473 spin_lock_irqsave(&p->sighand->siglock, flags);
1474 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1475 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1476 }
1477 force_sig(SIGSEGV, p);
1478 return 0;
1479}
1480
1481int kill_pgrp(struct pid *pid, int sig, int priv)
1482{
1483 int ret;
1484
1485 read_lock(&tasklist_lock);
1486 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1487 read_unlock(&tasklist_lock);
1488
1489 return ret;
1490}
1491EXPORT_SYMBOL(kill_pgrp);
1492
1493int kill_pid(struct pid *pid, int sig, int priv)
1494{
1495 return kill_pid_info(sig, __si_special(priv), pid);
1496}
1497EXPORT_SYMBOL(kill_pid);
1498
1499/*
1500 * These functions support sending signals using preallocated sigqueue
1501 * structures. This is needed "because realtime applications cannot
1502 * afford to lose notifications of asynchronous events, like timer
1503 * expirations or I/O completions". In the case of POSIX Timers
1504 * we allocate the sigqueue structure from the timer_create. If this
1505 * allocation fails we are able to report the failure to the application
1506 * with an EAGAIN error.
1507 */
1508struct sigqueue *sigqueue_alloc(void)
1509{
1510 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1511
1512 if (q)
1513 q->flags |= SIGQUEUE_PREALLOC;
1514
1515 return q;
1516}
1517
1518void sigqueue_free(struct sigqueue *q)
1519{
1520 unsigned long flags;
1521 spinlock_t *lock = ¤t->sighand->siglock;
1522
1523 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1524 /*
1525 * We must hold ->siglock while testing q->list
1526 * to serialize with collect_signal() or with
1527 * __exit_signal()->flush_sigqueue().
1528 */
1529 spin_lock_irqsave(lock, flags);
1530 q->flags &= ~SIGQUEUE_PREALLOC;
1531 /*
1532 * If it is queued it will be freed when dequeued,
1533 * like the "regular" sigqueue.
1534 */
1535 if (!list_empty(&q->list))
1536 q = NULL;
1537 spin_unlock_irqrestore(lock, flags);
1538
1539 if (q)
1540 __sigqueue_free(q);
1541}
1542
1543int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1544{
1545 int sig = q->info.si_signo;
1546 struct sigpending *pending;
1547 unsigned long flags;
1548 int ret;
1549
1550 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1551
1552 ret = -1;
1553 if (!likely(lock_task_sighand(t, &flags)))
1554 goto ret;
1555
1556 ret = 1; /* the signal is ignored */
1557 if (!prepare_signal(sig, t, 0))
1558 goto out;
1559
1560 ret = 0;
1561 if (unlikely(!list_empty(&q->list))) {
1562 /*
1563 * If an SI_TIMER entry is already queue just increment
1564 * the overrun count.
1565 */
1566 BUG_ON(q->info.si_code != SI_TIMER);
1567 q->info.si_overrun++;
1568 goto out;
1569 }
1570 q->info.si_overrun = 0;
1571
1572 signalfd_notify(t, sig);
1573 pending = group ? &t->signal->shared_pending : &t->pending;
1574 list_add_tail(&q->list, &pending->list);
1575 sigaddset(&pending->signal, sig);
1576 complete_signal(sig, t, group);
1577out:
1578 unlock_task_sighand(t, &flags);
1579ret:
1580 return ret;
1581}
1582
1583/*
1584 * Let a parent know about the death of a child.
1585 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1586 *
1587 * Returns true if our parent ignored us and so we've switched to
1588 * self-reaping.
1589 */
1590bool do_notify_parent(struct task_struct *tsk, int sig)
1591{
1592 struct siginfo info;
1593 unsigned long flags;
1594 struct sighand_struct *psig;
1595 bool autoreap = false;
1596
1597 BUG_ON(sig == -1);
1598
1599 /* do_notify_parent_cldstop should have been called instead. */
1600 BUG_ON(task_is_stopped_or_traced(tsk));
1601
1602 BUG_ON(!tsk->ptrace &&
1603 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1604
1605 info.si_signo = sig;
1606 info.si_errno = 0;
1607 /*
1608 * we are under tasklist_lock here so our parent is tied to
1609 * us and cannot exit and release its namespace.
1610 *
1611 * the only it can is to switch its nsproxy with sys_unshare,
1612 * bu uncharing pid namespaces is not allowed, so we'll always
1613 * see relevant namespace
1614 *
1615 * write_lock() currently calls preempt_disable() which is the
1616 * same as rcu_read_lock(), but according to Oleg, this is not
1617 * correct to rely on this
1618 */
1619 rcu_read_lock();
1620 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1621 info.si_uid = __task_cred(tsk)->uid;
1622 rcu_read_unlock();
1623
1624 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
1625 tsk->signal->utime));
1626 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
1627 tsk->signal->stime));
1628
1629 info.si_status = tsk->exit_code & 0x7f;
1630 if (tsk->exit_code & 0x80)
1631 info.si_code = CLD_DUMPED;
1632 else if (tsk->exit_code & 0x7f)
1633 info.si_code = CLD_KILLED;
1634 else {
1635 info.si_code = CLD_EXITED;
1636 info.si_status = tsk->exit_code >> 8;
1637 }
1638
1639 psig = tsk->parent->sighand;
1640 spin_lock_irqsave(&psig->siglock, flags);
1641 if (!tsk->ptrace && sig == SIGCHLD &&
1642 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1643 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1644 /*
1645 * We are exiting and our parent doesn't care. POSIX.1
1646 * defines special semantics for setting SIGCHLD to SIG_IGN
1647 * or setting the SA_NOCLDWAIT flag: we should be reaped
1648 * automatically and not left for our parent's wait4 call.
1649 * Rather than having the parent do it as a magic kind of
1650 * signal handler, we just set this to tell do_exit that we
1651 * can be cleaned up without becoming a zombie. Note that
1652 * we still call __wake_up_parent in this case, because a
1653 * blocked sys_wait4 might now return -ECHILD.
1654 *
1655 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1656 * is implementation-defined: we do (if you don't want
1657 * it, just use SIG_IGN instead).
1658 */
1659 autoreap = true;
1660 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1661 sig = 0;
1662 }
1663 if (valid_signal(sig) && sig)
1664 __group_send_sig_info(sig, &info, tsk->parent);
1665 __wake_up_parent(tsk, tsk->parent);
1666 spin_unlock_irqrestore(&psig->siglock, flags);
1667
1668 return autoreap;
1669}
1670
1671/**
1672 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1673 * @tsk: task reporting the state change
1674 * @for_ptracer: the notification is for ptracer
1675 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1676 *
1677 * Notify @tsk's parent that the stopped/continued state has changed. If
1678 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1679 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1680 *
1681 * CONTEXT:
1682 * Must be called with tasklist_lock at least read locked.
1683 */
1684static void do_notify_parent_cldstop(struct task_struct *tsk,
1685 bool for_ptracer, int why)
1686{
1687 struct siginfo info;
1688 unsigned long flags;
1689 struct task_struct *parent;
1690 struct sighand_struct *sighand;
1691
1692 if (for_ptracer) {
1693 parent = tsk->parent;
1694 } else {
1695 tsk = tsk->group_leader;
1696 parent = tsk->real_parent;
1697 }
1698
1699 info.si_signo = SIGCHLD;
1700 info.si_errno = 0;
1701 /*
1702 * see comment in do_notify_parent() about the following 4 lines
1703 */
1704 rcu_read_lock();
1705 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1706 info.si_uid = __task_cred(tsk)->uid;
1707 rcu_read_unlock();
1708
1709 info.si_utime = cputime_to_clock_t(tsk->utime);
1710 info.si_stime = cputime_to_clock_t(tsk->stime);
1711
1712 info.si_code = why;
1713 switch (why) {
1714 case CLD_CONTINUED:
1715 info.si_status = SIGCONT;
1716 break;
1717 case CLD_STOPPED:
1718 info.si_status = tsk->signal->group_exit_code & 0x7f;
1719 break;
1720 case CLD_TRAPPED:
1721 info.si_status = tsk->exit_code & 0x7f;
1722 break;
1723 default:
1724 BUG();
1725 }
1726
1727 sighand = parent->sighand;
1728 spin_lock_irqsave(&sighand->siglock, flags);
1729 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1730 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1731 __group_send_sig_info(SIGCHLD, &info, parent);
1732 /*
1733 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1734 */
1735 __wake_up_parent(tsk, parent);
1736 spin_unlock_irqrestore(&sighand->siglock, flags);
1737}
1738
1739static inline int may_ptrace_stop(void)
1740{
1741 if (!likely(current->ptrace))
1742 return 0;
1743 /*
1744 * Are we in the middle of do_coredump?
1745 * If so and our tracer is also part of the coredump stopping
1746 * is a deadlock situation, and pointless because our tracer
1747 * is dead so don't allow us to stop.
1748 * If SIGKILL was already sent before the caller unlocked
1749 * ->siglock we must see ->core_state != NULL. Otherwise it
1750 * is safe to enter schedule().
1751 */
1752 if (unlikely(current->mm->core_state) &&
1753 unlikely(current->mm == current->parent->mm))
1754 return 0;
1755
1756 return 1;
1757}
1758
1759/*
1760 * Return non-zero if there is a SIGKILL that should be waking us up.
1761 * Called with the siglock held.
1762 */
1763static int sigkill_pending(struct task_struct *tsk)
1764{
1765 return sigismember(&tsk->pending.signal, SIGKILL) ||
1766 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1767}
1768
1769/*
1770 * This must be called with current->sighand->siglock held.
1771 *
1772 * This should be the path for all ptrace stops.
1773 * We always set current->last_siginfo while stopped here.
1774 * That makes it a way to test a stopped process for
1775 * being ptrace-stopped vs being job-control-stopped.
1776 *
1777 * If we actually decide not to stop at all because the tracer
1778 * is gone, we keep current->exit_code unless clear_code.
1779 */
1780static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1781 __releases(¤t->sighand->siglock)
1782 __acquires(¤t->sighand->siglock)
1783{
1784 bool gstop_done = false;
1785
1786 if (arch_ptrace_stop_needed(exit_code, info)) {
1787 /*
1788 * The arch code has something special to do before a
1789 * ptrace stop. This is allowed to block, e.g. for faults
1790 * on user stack pages. We can't keep the siglock while
1791 * calling arch_ptrace_stop, so we must release it now.
1792 * To preserve proper semantics, we must do this before
1793 * any signal bookkeeping like checking group_stop_count.
1794 * Meanwhile, a SIGKILL could come in before we retake the
1795 * siglock. That must prevent us from sleeping in TASK_TRACED.
1796 * So after regaining the lock, we must check for SIGKILL.
1797 */
1798 spin_unlock_irq(¤t->sighand->siglock);
1799 arch_ptrace_stop(exit_code, info);
1800 spin_lock_irq(¤t->sighand->siglock);
1801 if (sigkill_pending(current))
1802 return;
1803 }
1804
1805 /*
1806 * We're committing to trapping. TRACED should be visible before
1807 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1808 * Also, transition to TRACED and updates to ->jobctl should be
1809 * atomic with respect to siglock and should be done after the arch
1810 * hook as siglock is released and regrabbed across it.
1811 */
1812 set_current_state(TASK_TRACED);
1813
1814 current->last_siginfo = info;
1815 current->exit_code = exit_code;
1816
1817 /*
1818 * If @why is CLD_STOPPED, we're trapping to participate in a group
1819 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1820 * across siglock relocks since INTERRUPT was scheduled, PENDING
1821 * could be clear now. We act as if SIGCONT is received after
1822 * TASK_TRACED is entered - ignore it.
1823 */
1824 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1825 gstop_done = task_participate_group_stop(current);
1826
1827 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1828 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1829 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1830 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1831
1832 /* entering a trap, clear TRAPPING */
1833 task_clear_jobctl_trapping(current);
1834
1835 spin_unlock_irq(¤t->sighand->siglock);
1836 read_lock(&tasklist_lock);
1837 if (may_ptrace_stop()) {
1838 /*
1839 * Notify parents of the stop.
1840 *
1841 * While ptraced, there are two parents - the ptracer and
1842 * the real_parent of the group_leader. The ptracer should
1843 * know about every stop while the real parent is only
1844 * interested in the completion of group stop. The states
1845 * for the two don't interact with each other. Notify
1846 * separately unless they're gonna be duplicates.
1847 */
1848 do_notify_parent_cldstop(current, true, why);
1849 if (gstop_done && ptrace_reparented(current))
1850 do_notify_parent_cldstop(current, false, why);
1851
1852 /*
1853 * Don't want to allow preemption here, because
1854 * sys_ptrace() needs this task to be inactive.
1855 *
1856 * XXX: implement read_unlock_no_resched().
1857 */
1858 preempt_disable();
1859 read_unlock(&tasklist_lock);
1860 preempt_enable_no_resched();
1861 schedule();
1862 } else {
1863 /*
1864 * By the time we got the lock, our tracer went away.
1865 * Don't drop the lock yet, another tracer may come.
1866 *
1867 * If @gstop_done, the ptracer went away between group stop
1868 * completion and here. During detach, it would have set
1869 * JOBCTL_STOP_PENDING on us and we'll re-enter
1870 * TASK_STOPPED in do_signal_stop() on return, so notifying
1871 * the real parent of the group stop completion is enough.
1872 */
1873 if (gstop_done)
1874 do_notify_parent_cldstop(current, false, why);
1875
1876 __set_current_state(TASK_RUNNING);
1877 if (clear_code)
1878 current->exit_code = 0;
1879 read_unlock(&tasklist_lock);
1880 }
1881
1882 /*
1883 * While in TASK_TRACED, we were considered "frozen enough".
1884 * Now that we woke up, it's crucial if we're supposed to be
1885 * frozen that we freeze now before running anything substantial.
1886 */
1887 try_to_freeze();
1888
1889 /*
1890 * We are back. Now reacquire the siglock before touching
1891 * last_siginfo, so that we are sure to have synchronized with
1892 * any signal-sending on another CPU that wants to examine it.
1893 */
1894 spin_lock_irq(¤t->sighand->siglock);
1895 current->last_siginfo = NULL;
1896
1897 /* LISTENING can be set only during STOP traps, clear it */
1898 current->jobctl &= ~JOBCTL_LISTENING;
1899
1900 /*
1901 * Queued signals ignored us while we were stopped for tracing.
1902 * So check for any that we should take before resuming user mode.
1903 * This sets TIF_SIGPENDING, but never clears it.
1904 */
1905 recalc_sigpending_tsk(current);
1906}
1907
1908static void ptrace_do_notify(int signr, int exit_code, int why)
1909{
1910 siginfo_t info;
1911
1912 memset(&info, 0, sizeof info);
1913 info.si_signo = signr;
1914 info.si_code = exit_code;
1915 info.si_pid = task_pid_vnr(current);
1916 info.si_uid = current_uid();
1917
1918 /* Let the debugger run. */
1919 ptrace_stop(exit_code, why, 1, &info);
1920}
1921
1922void ptrace_notify(int exit_code)
1923{
1924 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1925
1926 spin_lock_irq(¤t->sighand->siglock);
1927 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1928 spin_unlock_irq(¤t->sighand->siglock);
1929}
1930
1931/**
1932 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1933 * @signr: signr causing group stop if initiating
1934 *
1935 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1936 * and participate in it. If already set, participate in the existing
1937 * group stop. If participated in a group stop (and thus slept), %true is
1938 * returned with siglock released.
1939 *
1940 * If ptraced, this function doesn't handle stop itself. Instead,
1941 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1942 * untouched. The caller must ensure that INTERRUPT trap handling takes
1943 * places afterwards.
1944 *
1945 * CONTEXT:
1946 * Must be called with @current->sighand->siglock held, which is released
1947 * on %true return.
1948 *
1949 * RETURNS:
1950 * %false if group stop is already cancelled or ptrace trap is scheduled.
1951 * %true if participated in group stop.
1952 */
1953static bool do_signal_stop(int signr)
1954 __releases(¤t->sighand->siglock)
1955{
1956 struct signal_struct *sig = current->signal;
1957
1958 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1959 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1960 struct task_struct *t;
1961
1962 /* signr will be recorded in task->jobctl for retries */
1963 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1964
1965 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1966 unlikely(signal_group_exit(sig)))
1967 return false;
1968 /*
1969 * There is no group stop already in progress. We must
1970 * initiate one now.
1971 *
1972 * While ptraced, a task may be resumed while group stop is
1973 * still in effect and then receive a stop signal and
1974 * initiate another group stop. This deviates from the
1975 * usual behavior as two consecutive stop signals can't
1976 * cause two group stops when !ptraced. That is why we
1977 * also check !task_is_stopped(t) below.
1978 *
1979 * The condition can be distinguished by testing whether
1980 * SIGNAL_STOP_STOPPED is already set. Don't generate
1981 * group_exit_code in such case.
1982 *
1983 * This is not necessary for SIGNAL_STOP_CONTINUED because
1984 * an intervening stop signal is required to cause two
1985 * continued events regardless of ptrace.
1986 */
1987 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1988 sig->group_exit_code = signr;
1989 else
1990 WARN_ON_ONCE(!current->ptrace);
1991
1992 sig->group_stop_count = 0;
1993
1994 if (task_set_jobctl_pending(current, signr | gstop))
1995 sig->group_stop_count++;
1996
1997 for (t = next_thread(current); t != current;
1998 t = next_thread(t)) {
1999 /*
2000 * Setting state to TASK_STOPPED for a group
2001 * stop is always done with the siglock held,
2002 * so this check has no races.
2003 */
2004 if (!task_is_stopped(t) &&
2005 task_set_jobctl_pending(t, signr | gstop)) {
2006 sig->group_stop_count++;
2007 if (likely(!(t->ptrace & PT_SEIZED)))
2008 signal_wake_up(t, 0);
2009 else
2010 ptrace_trap_notify(t);
2011 }
2012 }
2013 }
2014
2015 if (likely(!current->ptrace)) {
2016 int notify = 0;
2017
2018 /*
2019 * If there are no other threads in the group, or if there
2020 * is a group stop in progress and we are the last to stop,
2021 * report to the parent.
2022 */
2023 if (task_participate_group_stop(current))
2024 notify = CLD_STOPPED;
2025
2026 __set_current_state(TASK_STOPPED);
2027 spin_unlock_irq(¤t->sighand->siglock);
2028
2029 /*
2030 * Notify the parent of the group stop completion. Because
2031 * we're not holding either the siglock or tasklist_lock
2032 * here, ptracer may attach inbetween; however, this is for
2033 * group stop and should always be delivered to the real
2034 * parent of the group leader. The new ptracer will get
2035 * its notification when this task transitions into
2036 * TASK_TRACED.
2037 */
2038 if (notify) {
2039 read_lock(&tasklist_lock);
2040 do_notify_parent_cldstop(current, false, notify);
2041 read_unlock(&tasklist_lock);
2042 }
2043
2044 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2045 schedule();
2046 return true;
2047 } else {
2048 /*
2049 * While ptraced, group stop is handled by STOP trap.
2050 * Schedule it and let the caller deal with it.
2051 */
2052 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2053 return false;
2054 }
2055}
2056
2057/**
2058 * do_jobctl_trap - take care of ptrace jobctl traps
2059 *
2060 * When PT_SEIZED, it's used for both group stop and explicit
2061 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2062 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2063 * the stop signal; otherwise, %SIGTRAP.
2064 *
2065 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2066 * number as exit_code and no siginfo.
2067 *
2068 * CONTEXT:
2069 * Must be called with @current->sighand->siglock held, which may be
2070 * released and re-acquired before returning with intervening sleep.
2071 */
2072static void do_jobctl_trap(void)
2073{
2074 struct signal_struct *signal = current->signal;
2075 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2076
2077 if (current->ptrace & PT_SEIZED) {
2078 if (!signal->group_stop_count &&
2079 !(signal->flags & SIGNAL_STOP_STOPPED))
2080 signr = SIGTRAP;
2081 WARN_ON_ONCE(!signr);
2082 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2083 CLD_STOPPED);
2084 } else {
2085 WARN_ON_ONCE(!signr);
2086 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2087 current->exit_code = 0;
2088 }
2089}
2090
2091static int ptrace_signal(int signr, siginfo_t *info,
2092 struct pt_regs *regs, void *cookie)
2093{
2094 ptrace_signal_deliver(regs, cookie);
2095 /*
2096 * We do not check sig_kernel_stop(signr) but set this marker
2097 * unconditionally because we do not know whether debugger will
2098 * change signr. This flag has no meaning unless we are going
2099 * to stop after return from ptrace_stop(). In this case it will
2100 * be checked in do_signal_stop(), we should only stop if it was
2101 * not cleared by SIGCONT while we were sleeping. See also the
2102 * comment in dequeue_signal().
2103 */
2104 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2105 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2106
2107 /* We're back. Did the debugger cancel the sig? */
2108 signr = current->exit_code;
2109 if (signr == 0)
2110 return signr;
2111
2112 current->exit_code = 0;
2113
2114 /*
2115 * Update the siginfo structure if the signal has
2116 * changed. If the debugger wanted something
2117 * specific in the siginfo structure then it should
2118 * have updated *info via PTRACE_SETSIGINFO.
2119 */
2120 if (signr != info->si_signo) {
2121 info->si_signo = signr;
2122 info->si_errno = 0;
2123 info->si_code = SI_USER;
2124 info->si_pid = task_pid_vnr(current->parent);
2125 info->si_uid = task_uid(current->parent);
2126 }
2127
2128 /* If the (new) signal is now blocked, requeue it. */
2129 if (sigismember(¤t->blocked, signr)) {
2130 specific_send_sig_info(signr, info, current);
2131 signr = 0;
2132 }
2133
2134 return signr;
2135}
2136
2137int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2138 struct pt_regs *regs, void *cookie)
2139{
2140 struct sighand_struct *sighand = current->sighand;
2141 struct signal_struct *signal = current->signal;
2142 int signr;
2143
2144relock:
2145 /*
2146 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2147 * While in TASK_STOPPED, we were considered "frozen enough".
2148 * Now that we woke up, it's crucial if we're supposed to be
2149 * frozen that we freeze now before running anything substantial.
2150 */
2151 try_to_freeze();
2152
2153 spin_lock_irq(&sighand->siglock);
2154 /*
2155 * Every stopped thread goes here after wakeup. Check to see if
2156 * we should notify the parent, prepare_signal(SIGCONT) encodes
2157 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2158 */
2159 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2160 int why;
2161
2162 if (signal->flags & SIGNAL_CLD_CONTINUED)
2163 why = CLD_CONTINUED;
2164 else
2165 why = CLD_STOPPED;
2166
2167 signal->flags &= ~SIGNAL_CLD_MASK;
2168
2169 spin_unlock_irq(&sighand->siglock);
2170
2171 /*
2172 * Notify the parent that we're continuing. This event is
2173 * always per-process and doesn't make whole lot of sense
2174 * for ptracers, who shouldn't consume the state via
2175 * wait(2) either, but, for backward compatibility, notify
2176 * the ptracer of the group leader too unless it's gonna be
2177 * a duplicate.
2178 */
2179 read_lock(&tasklist_lock);
2180 do_notify_parent_cldstop(current, false, why);
2181
2182 if (ptrace_reparented(current->group_leader))
2183 do_notify_parent_cldstop(current->group_leader,
2184 true, why);
2185 read_unlock(&tasklist_lock);
2186
2187 goto relock;
2188 }
2189
2190 for (;;) {
2191 struct k_sigaction *ka;
2192
2193 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2194 do_signal_stop(0))
2195 goto relock;
2196
2197 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2198 do_jobctl_trap();
2199 spin_unlock_irq(&sighand->siglock);
2200 goto relock;
2201 }
2202
2203 signr = dequeue_signal(current, ¤t->blocked, info);
2204
2205 if (!signr)
2206 break; /* will return 0 */
2207
2208 if (unlikely(current->ptrace) && signr != SIGKILL) {
2209 signr = ptrace_signal(signr, info,
2210 regs, cookie);
2211 if (!signr)
2212 continue;
2213 }
2214
2215 ka = &sighand->action[signr-1];
2216
2217 /* Trace actually delivered signals. */
2218 trace_signal_deliver(signr, info, ka);
2219
2220 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2221 continue;
2222 if (ka->sa.sa_handler != SIG_DFL) {
2223 /* Run the handler. */
2224 *return_ka = *ka;
2225
2226 if (ka->sa.sa_flags & SA_ONESHOT)
2227 ka->sa.sa_handler = SIG_DFL;
2228
2229 break; /* will return non-zero "signr" value */
2230 }
2231
2232 /*
2233 * Now we are doing the default action for this signal.
2234 */
2235 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2236 continue;
2237
2238 /*
2239 * Global init gets no signals it doesn't want.
2240 * Container-init gets no signals it doesn't want from same
2241 * container.
2242 *
2243 * Note that if global/container-init sees a sig_kernel_only()
2244 * signal here, the signal must have been generated internally
2245 * or must have come from an ancestor namespace. In either
2246 * case, the signal cannot be dropped.
2247 */
2248 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2249 !sig_kernel_only(signr))
2250 continue;
2251
2252 if (sig_kernel_stop(signr)) {
2253 /*
2254 * The default action is to stop all threads in
2255 * the thread group. The job control signals
2256 * do nothing in an orphaned pgrp, but SIGSTOP
2257 * always works. Note that siglock needs to be
2258 * dropped during the call to is_orphaned_pgrp()
2259 * because of lock ordering with tasklist_lock.
2260 * This allows an intervening SIGCONT to be posted.
2261 * We need to check for that and bail out if necessary.
2262 */
2263 if (signr != SIGSTOP) {
2264 spin_unlock_irq(&sighand->siglock);
2265
2266 /* signals can be posted during this window */
2267
2268 if (is_current_pgrp_orphaned())
2269 goto relock;
2270
2271 spin_lock_irq(&sighand->siglock);
2272 }
2273
2274 if (likely(do_signal_stop(info->si_signo))) {
2275 /* It released the siglock. */
2276 goto relock;
2277 }
2278
2279 /*
2280 * We didn't actually stop, due to a race
2281 * with SIGCONT or something like that.
2282 */
2283 continue;
2284 }
2285
2286 spin_unlock_irq(&sighand->siglock);
2287
2288 /*
2289 * Anything else is fatal, maybe with a core dump.
2290 */
2291 current->flags |= PF_SIGNALED;
2292
2293 if (sig_kernel_coredump(signr)) {
2294 if (print_fatal_signals)
2295 print_fatal_signal(regs, info->si_signo);
2296 /*
2297 * If it was able to dump core, this kills all
2298 * other threads in the group and synchronizes with
2299 * their demise. If we lost the race with another
2300 * thread getting here, it set group_exit_code
2301 * first and our do_group_exit call below will use
2302 * that value and ignore the one we pass it.
2303 */
2304 do_coredump(info->si_signo, info->si_signo, regs);
2305 }
2306
2307 /*
2308 * Death signals, no core dump.
2309 */
2310 do_group_exit(info->si_signo);
2311 /* NOTREACHED */
2312 }
2313 spin_unlock_irq(&sighand->siglock);
2314 return signr;
2315}
2316
2317/*
2318 * It could be that complete_signal() picked us to notify about the
2319 * group-wide signal. Other threads should be notified now to take
2320 * the shared signals in @which since we will not.
2321 */
2322static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2323{
2324 sigset_t retarget;
2325 struct task_struct *t;
2326
2327 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2328 if (sigisemptyset(&retarget))
2329 return;
2330
2331 t = tsk;
2332 while_each_thread(tsk, t) {
2333 if (t->flags & PF_EXITING)
2334 continue;
2335
2336 if (!has_pending_signals(&retarget, &t->blocked))
2337 continue;
2338 /* Remove the signals this thread can handle. */
2339 sigandsets(&retarget, &retarget, &t->blocked);
2340
2341 if (!signal_pending(t))
2342 signal_wake_up(t, 0);
2343
2344 if (sigisemptyset(&retarget))
2345 break;
2346 }
2347}
2348
2349void exit_signals(struct task_struct *tsk)
2350{
2351 int group_stop = 0;
2352 sigset_t unblocked;
2353
2354 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2355 tsk->flags |= PF_EXITING;
2356 return;
2357 }
2358
2359 spin_lock_irq(&tsk->sighand->siglock);
2360 /*
2361 * From now this task is not visible for group-wide signals,
2362 * see wants_signal(), do_signal_stop().
2363 */
2364 tsk->flags |= PF_EXITING;
2365 if (!signal_pending(tsk))
2366 goto out;
2367
2368 unblocked = tsk->blocked;
2369 signotset(&unblocked);
2370 retarget_shared_pending(tsk, &unblocked);
2371
2372 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2373 task_participate_group_stop(tsk))
2374 group_stop = CLD_STOPPED;
2375out:
2376 spin_unlock_irq(&tsk->sighand->siglock);
2377
2378 /*
2379 * If group stop has completed, deliver the notification. This
2380 * should always go to the real parent of the group leader.
2381 */
2382 if (unlikely(group_stop)) {
2383 read_lock(&tasklist_lock);
2384 do_notify_parent_cldstop(tsk, false, group_stop);
2385 read_unlock(&tasklist_lock);
2386 }
2387}
2388
2389EXPORT_SYMBOL(recalc_sigpending);
2390EXPORT_SYMBOL_GPL(dequeue_signal);
2391EXPORT_SYMBOL(flush_signals);
2392EXPORT_SYMBOL(force_sig);
2393EXPORT_SYMBOL(send_sig);
2394EXPORT_SYMBOL(send_sig_info);
2395EXPORT_SYMBOL(sigprocmask);
2396EXPORT_SYMBOL(block_all_signals);
2397EXPORT_SYMBOL(unblock_all_signals);
2398
2399
2400/*
2401 * System call entry points.
2402 */
2403
2404/**
2405 * sys_restart_syscall - restart a system call
2406 */
2407SYSCALL_DEFINE0(restart_syscall)
2408{
2409 struct restart_block *restart = ¤t_thread_info()->restart_block;
2410 return restart->fn(restart);
2411}
2412
2413long do_no_restart_syscall(struct restart_block *param)
2414{
2415 return -EINTR;
2416}
2417
2418static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2419{
2420 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2421 sigset_t newblocked;
2422 /* A set of now blocked but previously unblocked signals. */
2423 sigandnsets(&newblocked, newset, ¤t->blocked);
2424 retarget_shared_pending(tsk, &newblocked);
2425 }
2426 tsk->blocked = *newset;
2427 recalc_sigpending();
2428}
2429
2430/**
2431 * set_current_blocked - change current->blocked mask
2432 * @newset: new mask
2433 *
2434 * It is wrong to change ->blocked directly, this helper should be used
2435 * to ensure the process can't miss a shared signal we are going to block.
2436 */
2437void set_current_blocked(const sigset_t *newset)
2438{
2439 struct task_struct *tsk = current;
2440
2441 spin_lock_irq(&tsk->sighand->siglock);
2442 __set_task_blocked(tsk, newset);
2443 spin_unlock_irq(&tsk->sighand->siglock);
2444}
2445
2446/*
2447 * This is also useful for kernel threads that want to temporarily
2448 * (or permanently) block certain signals.
2449 *
2450 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2451 * interface happily blocks "unblockable" signals like SIGKILL
2452 * and friends.
2453 */
2454int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2455{
2456 struct task_struct *tsk = current;
2457 sigset_t newset;
2458
2459 /* Lockless, only current can change ->blocked, never from irq */
2460 if (oldset)
2461 *oldset = tsk->blocked;
2462
2463 switch (how) {
2464 case SIG_BLOCK:
2465 sigorsets(&newset, &tsk->blocked, set);
2466 break;
2467 case SIG_UNBLOCK:
2468 sigandnsets(&newset, &tsk->blocked, set);
2469 break;
2470 case SIG_SETMASK:
2471 newset = *set;
2472 break;
2473 default:
2474 return -EINVAL;
2475 }
2476
2477 set_current_blocked(&newset);
2478 return 0;
2479}
2480
2481/**
2482 * sys_rt_sigprocmask - change the list of currently blocked signals
2483 * @how: whether to add, remove, or set signals
2484 * @nset: stores pending signals
2485 * @oset: previous value of signal mask if non-null
2486 * @sigsetsize: size of sigset_t type
2487 */
2488SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2489 sigset_t __user *, oset, size_t, sigsetsize)
2490{
2491 sigset_t old_set, new_set;
2492 int error;
2493
2494 /* XXX: Don't preclude handling different sized sigset_t's. */
2495 if (sigsetsize != sizeof(sigset_t))
2496 return -EINVAL;
2497
2498 old_set = current->blocked;
2499
2500 if (nset) {
2501 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2502 return -EFAULT;
2503 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2504
2505 error = sigprocmask(how, &new_set, NULL);
2506 if (error)
2507 return error;
2508 }
2509
2510 if (oset) {
2511 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2512 return -EFAULT;
2513 }
2514
2515 return 0;
2516}
2517
2518long do_sigpending(void __user *set, unsigned long sigsetsize)
2519{
2520 long error = -EINVAL;
2521 sigset_t pending;
2522
2523 if (sigsetsize > sizeof(sigset_t))
2524 goto out;
2525
2526 spin_lock_irq(¤t->sighand->siglock);
2527 sigorsets(&pending, ¤t->pending.signal,
2528 ¤t->signal->shared_pending.signal);
2529 spin_unlock_irq(¤t->sighand->siglock);
2530
2531 /* Outside the lock because only this thread touches it. */
2532 sigandsets(&pending, ¤t->blocked, &pending);
2533
2534 error = -EFAULT;
2535 if (!copy_to_user(set, &pending, sigsetsize))
2536 error = 0;
2537
2538out:
2539 return error;
2540}
2541
2542/**
2543 * sys_rt_sigpending - examine a pending signal that has been raised
2544 * while blocked
2545 * @set: stores pending signals
2546 * @sigsetsize: size of sigset_t type or larger
2547 */
2548SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2549{
2550 return do_sigpending(set, sigsetsize);
2551}
2552
2553#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2554
2555int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2556{
2557 int err;
2558
2559 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2560 return -EFAULT;
2561 if (from->si_code < 0)
2562 return __copy_to_user(to, from, sizeof(siginfo_t))
2563 ? -EFAULT : 0;
2564 /*
2565 * If you change siginfo_t structure, please be sure
2566 * this code is fixed accordingly.
2567 * Please remember to update the signalfd_copyinfo() function
2568 * inside fs/signalfd.c too, in case siginfo_t changes.
2569 * It should never copy any pad contained in the structure
2570 * to avoid security leaks, but must copy the generic
2571 * 3 ints plus the relevant union member.
2572 */
2573 err = __put_user(from->si_signo, &to->si_signo);
2574 err |= __put_user(from->si_errno, &to->si_errno);
2575 err |= __put_user((short)from->si_code, &to->si_code);
2576 switch (from->si_code & __SI_MASK) {
2577 case __SI_KILL:
2578 err |= __put_user(from->si_pid, &to->si_pid);
2579 err |= __put_user(from->si_uid, &to->si_uid);
2580 break;
2581 case __SI_TIMER:
2582 err |= __put_user(from->si_tid, &to->si_tid);
2583 err |= __put_user(from->si_overrun, &to->si_overrun);
2584 err |= __put_user(from->si_ptr, &to->si_ptr);
2585 break;
2586 case __SI_POLL:
2587 err |= __put_user(from->si_band, &to->si_band);
2588 err |= __put_user(from->si_fd, &to->si_fd);
2589 break;
2590 case __SI_FAULT:
2591 err |= __put_user(from->si_addr, &to->si_addr);
2592#ifdef __ARCH_SI_TRAPNO
2593 err |= __put_user(from->si_trapno, &to->si_trapno);
2594#endif
2595#ifdef BUS_MCEERR_AO
2596 /*
2597 * Other callers might not initialize the si_lsb field,
2598 * so check explicitly for the right codes here.
2599 */
2600 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2601 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2602#endif
2603 break;
2604 case __SI_CHLD:
2605 err |= __put_user(from->si_pid, &to->si_pid);
2606 err |= __put_user(from->si_uid, &to->si_uid);
2607 err |= __put_user(from->si_status, &to->si_status);
2608 err |= __put_user(from->si_utime, &to->si_utime);
2609 err |= __put_user(from->si_stime, &to->si_stime);
2610 break;
2611 case __SI_RT: /* This is not generated by the kernel as of now. */
2612 case __SI_MESGQ: /* But this is */
2613 err |= __put_user(from->si_pid, &to->si_pid);
2614 err |= __put_user(from->si_uid, &to->si_uid);
2615 err |= __put_user(from->si_ptr, &to->si_ptr);
2616 break;
2617 default: /* this is just in case for now ... */
2618 err |= __put_user(from->si_pid, &to->si_pid);
2619 err |= __put_user(from->si_uid, &to->si_uid);
2620 break;
2621 }
2622 return err;
2623}
2624
2625#endif
2626
2627/**
2628 * do_sigtimedwait - wait for queued signals specified in @which
2629 * @which: queued signals to wait for
2630 * @info: if non-null, the signal's siginfo is returned here
2631 * @ts: upper bound on process time suspension
2632 */
2633int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2634 const struct timespec *ts)
2635{
2636 struct task_struct *tsk = current;
2637 long timeout = MAX_SCHEDULE_TIMEOUT;
2638 sigset_t mask = *which;
2639 int sig;
2640
2641 if (ts) {
2642 if (!timespec_valid(ts))
2643 return -EINVAL;
2644 timeout = timespec_to_jiffies(ts);
2645 /*
2646 * We can be close to the next tick, add another one
2647 * to ensure we will wait at least the time asked for.
2648 */
2649 if (ts->tv_sec || ts->tv_nsec)
2650 timeout++;
2651 }
2652
2653 /*
2654 * Invert the set of allowed signals to get those we want to block.
2655 */
2656 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2657 signotset(&mask);
2658
2659 spin_lock_irq(&tsk->sighand->siglock);
2660 sig = dequeue_signal(tsk, &mask, info);
2661 if (!sig && timeout) {
2662 /*
2663 * None ready, temporarily unblock those we're interested
2664 * while we are sleeping in so that we'll be awakened when
2665 * they arrive. Unblocking is always fine, we can avoid
2666 * set_current_blocked().
2667 */
2668 tsk->real_blocked = tsk->blocked;
2669 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2670 recalc_sigpending();
2671 spin_unlock_irq(&tsk->sighand->siglock);
2672
2673 timeout = schedule_timeout_interruptible(timeout);
2674
2675 spin_lock_irq(&tsk->sighand->siglock);
2676 __set_task_blocked(tsk, &tsk->real_blocked);
2677 siginitset(&tsk->real_blocked, 0);
2678 sig = dequeue_signal(tsk, &mask, info);
2679 }
2680 spin_unlock_irq(&tsk->sighand->siglock);
2681
2682 if (sig)
2683 return sig;
2684 return timeout ? -EINTR : -EAGAIN;
2685}
2686
2687/**
2688 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2689 * in @uthese
2690 * @uthese: queued signals to wait for
2691 * @uinfo: if non-null, the signal's siginfo is returned here
2692 * @uts: upper bound on process time suspension
2693 * @sigsetsize: size of sigset_t type
2694 */
2695SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2696 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2697 size_t, sigsetsize)
2698{
2699 sigset_t these;
2700 struct timespec ts;
2701 siginfo_t info;
2702 int ret;
2703
2704 /* XXX: Don't preclude handling different sized sigset_t's. */
2705 if (sigsetsize != sizeof(sigset_t))
2706 return -EINVAL;
2707
2708 if (copy_from_user(&these, uthese, sizeof(these)))
2709 return -EFAULT;
2710
2711 if (uts) {
2712 if (copy_from_user(&ts, uts, sizeof(ts)))
2713 return -EFAULT;
2714 }
2715
2716 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2717
2718 if (ret > 0 && uinfo) {
2719 if (copy_siginfo_to_user(uinfo, &info))
2720 ret = -EFAULT;
2721 }
2722
2723 return ret;
2724}
2725
2726/**
2727 * sys_kill - send a signal to a process
2728 * @pid: the PID of the process
2729 * @sig: signal to be sent
2730 */
2731SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2732{
2733 struct siginfo info;
2734
2735 info.si_signo = sig;
2736 info.si_errno = 0;
2737 info.si_code = SI_USER;
2738 info.si_pid = task_tgid_vnr(current);
2739 info.si_uid = current_uid();
2740
2741 return kill_something_info(sig, &info, pid);
2742}
2743
2744static int
2745do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2746{
2747 struct task_struct *p;
2748 int error = -ESRCH;
2749
2750 rcu_read_lock();
2751 p = find_task_by_vpid(pid);
2752 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2753 error = check_kill_permission(sig, info, p);
2754 /*
2755 * The null signal is a permissions and process existence
2756 * probe. No signal is actually delivered.
2757 */
2758 if (!error && sig) {
2759 error = do_send_sig_info(sig, info, p, false);
2760 /*
2761 * If lock_task_sighand() failed we pretend the task
2762 * dies after receiving the signal. The window is tiny,
2763 * and the signal is private anyway.
2764 */
2765 if (unlikely(error == -ESRCH))
2766 error = 0;
2767 }
2768 }
2769 rcu_read_unlock();
2770
2771 return error;
2772}
2773
2774static int do_tkill(pid_t tgid, pid_t pid, int sig)
2775{
2776 struct siginfo info;
2777
2778 info.si_signo = sig;
2779 info.si_errno = 0;
2780 info.si_code = SI_TKILL;
2781 info.si_pid = task_tgid_vnr(current);
2782 info.si_uid = current_uid();
2783
2784 return do_send_specific(tgid, pid, sig, &info);
2785}
2786
2787/**
2788 * sys_tgkill - send signal to one specific thread
2789 * @tgid: the thread group ID of the thread
2790 * @pid: the PID of the thread
2791 * @sig: signal to be sent
2792 *
2793 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2794 * exists but it's not belonging to the target process anymore. This
2795 * method solves the problem of threads exiting and PIDs getting reused.
2796 */
2797SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2798{
2799 /* This is only valid for single tasks */
2800 if (pid <= 0 || tgid <= 0)
2801 return -EINVAL;
2802
2803 return do_tkill(tgid, pid, sig);
2804}
2805
2806/**
2807 * sys_tkill - send signal to one specific task
2808 * @pid: the PID of the task
2809 * @sig: signal to be sent
2810 *
2811 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2812 */
2813SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2814{
2815 /* This is only valid for single tasks */
2816 if (pid <= 0)
2817 return -EINVAL;
2818
2819 return do_tkill(0, pid, sig);
2820}
2821
2822/**
2823 * sys_rt_sigqueueinfo - send signal information to a signal
2824 * @pid: the PID of the thread
2825 * @sig: signal to be sent
2826 * @uinfo: signal info to be sent
2827 */
2828SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2829 siginfo_t __user *, uinfo)
2830{
2831 siginfo_t info;
2832
2833 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2834 return -EFAULT;
2835
2836 /* Not even root can pretend to send signals from the kernel.
2837 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2838 */
2839 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2840 /* We used to allow any < 0 si_code */
2841 WARN_ON_ONCE(info.si_code < 0);
2842 return -EPERM;
2843 }
2844 info.si_signo = sig;
2845
2846 /* POSIX.1b doesn't mention process groups. */
2847 return kill_proc_info(sig, &info, pid);
2848}
2849
2850long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2851{
2852 /* This is only valid for single tasks */
2853 if (pid <= 0 || tgid <= 0)
2854 return -EINVAL;
2855
2856 /* Not even root can pretend to send signals from the kernel.
2857 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2858 */
2859 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2860 /* We used to allow any < 0 si_code */
2861 WARN_ON_ONCE(info->si_code < 0);
2862 return -EPERM;
2863 }
2864 info->si_signo = sig;
2865
2866 return do_send_specific(tgid, pid, sig, info);
2867}
2868
2869SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2870 siginfo_t __user *, uinfo)
2871{
2872 siginfo_t info;
2873
2874 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2875 return -EFAULT;
2876
2877 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2878}
2879
2880int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2881{
2882 struct task_struct *t = current;
2883 struct k_sigaction *k;
2884 sigset_t mask;
2885
2886 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2887 return -EINVAL;
2888
2889 k = &t->sighand->action[sig-1];
2890
2891 spin_lock_irq(¤t->sighand->siglock);
2892 if (oact)
2893 *oact = *k;
2894
2895 if (act) {
2896 sigdelsetmask(&act->sa.sa_mask,
2897 sigmask(SIGKILL) | sigmask(SIGSTOP));
2898 *k = *act;
2899 /*
2900 * POSIX 3.3.1.3:
2901 * "Setting a signal action to SIG_IGN for a signal that is
2902 * pending shall cause the pending signal to be discarded,
2903 * whether or not it is blocked."
2904 *
2905 * "Setting a signal action to SIG_DFL for a signal that is
2906 * pending and whose default action is to ignore the signal
2907 * (for example, SIGCHLD), shall cause the pending signal to
2908 * be discarded, whether or not it is blocked"
2909 */
2910 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
2911 sigemptyset(&mask);
2912 sigaddset(&mask, sig);
2913 rm_from_queue_full(&mask, &t->signal->shared_pending);
2914 do {
2915 rm_from_queue_full(&mask, &t->pending);
2916 t = next_thread(t);
2917 } while (t != current);
2918 }
2919 }
2920
2921 spin_unlock_irq(¤t->sighand->siglock);
2922 return 0;
2923}
2924
2925int
2926do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2927{
2928 stack_t oss;
2929 int error;
2930
2931 oss.ss_sp = (void __user *) current->sas_ss_sp;
2932 oss.ss_size = current->sas_ss_size;
2933 oss.ss_flags = sas_ss_flags(sp);
2934
2935 if (uss) {
2936 void __user *ss_sp;
2937 size_t ss_size;
2938 int ss_flags;
2939
2940 error = -EFAULT;
2941 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
2942 goto out;
2943 error = __get_user(ss_sp, &uss->ss_sp) |
2944 __get_user(ss_flags, &uss->ss_flags) |
2945 __get_user(ss_size, &uss->ss_size);
2946 if (error)
2947 goto out;
2948
2949 error = -EPERM;
2950 if (on_sig_stack(sp))
2951 goto out;
2952
2953 error = -EINVAL;
2954 /*
2955 * Note - this code used to test ss_flags incorrectly:
2956 * old code may have been written using ss_flags==0
2957 * to mean ss_flags==SS_ONSTACK (as this was the only
2958 * way that worked) - this fix preserves that older
2959 * mechanism.
2960 */
2961 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2962 goto out;
2963
2964 if (ss_flags == SS_DISABLE) {
2965 ss_size = 0;
2966 ss_sp = NULL;
2967 } else {
2968 error = -ENOMEM;
2969 if (ss_size < MINSIGSTKSZ)
2970 goto out;
2971 }
2972
2973 current->sas_ss_sp = (unsigned long) ss_sp;
2974 current->sas_ss_size = ss_size;
2975 }
2976
2977 error = 0;
2978 if (uoss) {
2979 error = -EFAULT;
2980 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
2981 goto out;
2982 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
2983 __put_user(oss.ss_size, &uoss->ss_size) |
2984 __put_user(oss.ss_flags, &uoss->ss_flags);
2985 }
2986
2987out:
2988 return error;
2989}
2990
2991#ifdef __ARCH_WANT_SYS_SIGPENDING
2992
2993/**
2994 * sys_sigpending - examine pending signals
2995 * @set: where mask of pending signal is returned
2996 */
2997SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
2998{
2999 return do_sigpending(set, sizeof(*set));
3000}
3001
3002#endif
3003
3004#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3005/**
3006 * sys_sigprocmask - examine and change blocked signals
3007 * @how: whether to add, remove, or set signals
3008 * @nset: signals to add or remove (if non-null)
3009 * @oset: previous value of signal mask if non-null
3010 *
3011 * Some platforms have their own version with special arguments;
3012 * others support only sys_rt_sigprocmask.
3013 */
3014
3015SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3016 old_sigset_t __user *, oset)
3017{
3018 old_sigset_t old_set, new_set;
3019 sigset_t new_blocked;
3020
3021 old_set = current->blocked.sig[0];
3022
3023 if (nset) {
3024 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3025 return -EFAULT;
3026 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3027
3028 new_blocked = current->blocked;
3029
3030 switch (how) {
3031 case SIG_BLOCK:
3032 sigaddsetmask(&new_blocked, new_set);
3033 break;
3034 case SIG_UNBLOCK:
3035 sigdelsetmask(&new_blocked, new_set);
3036 break;
3037 case SIG_SETMASK:
3038 new_blocked.sig[0] = new_set;
3039 break;
3040 default:
3041 return -EINVAL;
3042 }
3043
3044 set_current_blocked(&new_blocked);
3045 }
3046
3047 if (oset) {
3048 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3049 return -EFAULT;
3050 }
3051
3052 return 0;
3053}
3054#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3055
3056#ifdef __ARCH_WANT_SYS_RT_SIGACTION
3057/**
3058 * sys_rt_sigaction - alter an action taken by a process
3059 * @sig: signal to be sent
3060 * @act: new sigaction
3061 * @oact: used to save the previous sigaction
3062 * @sigsetsize: size of sigset_t type
3063 */
3064SYSCALL_DEFINE4(rt_sigaction, int, sig,
3065 const struct sigaction __user *, act,
3066 struct sigaction __user *, oact,
3067 size_t, sigsetsize)
3068{
3069 struct k_sigaction new_sa, old_sa;
3070 int ret = -EINVAL;
3071
3072 /* XXX: Don't preclude handling different sized sigset_t's. */
3073 if (sigsetsize != sizeof(sigset_t))
3074 goto out;
3075
3076 if (act) {
3077 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3078 return -EFAULT;
3079 }
3080
3081 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3082
3083 if (!ret && oact) {
3084 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3085 return -EFAULT;
3086 }
3087out:
3088 return ret;
3089}
3090#endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3091
3092#ifdef __ARCH_WANT_SYS_SGETMASK
3093
3094/*
3095 * For backwards compatibility. Functionality superseded by sigprocmask.
3096 */
3097SYSCALL_DEFINE0(sgetmask)
3098{
3099 /* SMP safe */
3100 return current->blocked.sig[0];
3101}
3102
3103SYSCALL_DEFINE1(ssetmask, int, newmask)
3104{
3105 int old = current->blocked.sig[0];
3106 sigset_t newset;
3107
3108 siginitset(&newset, newmask & ~(sigmask(SIGKILL) | sigmask(SIGSTOP)));
3109 set_current_blocked(&newset);
3110
3111 return old;
3112}
3113#endif /* __ARCH_WANT_SGETMASK */
3114
3115#ifdef __ARCH_WANT_SYS_SIGNAL
3116/*
3117 * For backwards compatibility. Functionality superseded by sigaction.
3118 */
3119SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3120{
3121 struct k_sigaction new_sa, old_sa;
3122 int ret;
3123
3124 new_sa.sa.sa_handler = handler;
3125 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3126 sigemptyset(&new_sa.sa.sa_mask);
3127
3128 ret = do_sigaction(sig, &new_sa, &old_sa);
3129
3130 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3131}
3132#endif /* __ARCH_WANT_SYS_SIGNAL */
3133
3134#ifdef __ARCH_WANT_SYS_PAUSE
3135
3136SYSCALL_DEFINE0(pause)
3137{
3138 while (!signal_pending(current)) {
3139 current->state = TASK_INTERRUPTIBLE;
3140 schedule();
3141 }
3142 return -ERESTARTNOHAND;
3143}
3144
3145#endif
3146
3147#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3148/**
3149 * sys_rt_sigsuspend - replace the signal mask for a value with the
3150 * @unewset value until a signal is received
3151 * @unewset: new signal mask value
3152 * @sigsetsize: size of sigset_t type
3153 */
3154SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3155{
3156 sigset_t newset;
3157
3158 /* XXX: Don't preclude handling different sized sigset_t's. */
3159 if (sigsetsize != sizeof(sigset_t))
3160 return -EINVAL;
3161
3162 if (copy_from_user(&newset, unewset, sizeof(newset)))
3163 return -EFAULT;
3164 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
3165
3166 current->saved_sigmask = current->blocked;
3167 set_current_blocked(&newset);
3168
3169 current->state = TASK_INTERRUPTIBLE;
3170 schedule();
3171 set_restore_sigmask();
3172 return -ERESTARTNOHAND;
3173}
3174#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3175
3176__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3177{
3178 return NULL;
3179}
3180
3181void __init signals_init(void)
3182{
3183 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3184}
3185
3186#ifdef CONFIG_KGDB_KDB
3187#include <linux/kdb.h>
3188/*
3189 * kdb_send_sig_info - Allows kdb to send signals without exposing
3190 * signal internals. This function checks if the required locks are
3191 * available before calling the main signal code, to avoid kdb
3192 * deadlocks.
3193 */
3194void
3195kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3196{
3197 static struct task_struct *kdb_prev_t;
3198 int sig, new_t;
3199 if (!spin_trylock(&t->sighand->siglock)) {
3200 kdb_printf("Can't do kill command now.\n"
3201 "The sigmask lock is held somewhere else in "
3202 "kernel, try again later\n");
3203 return;
3204 }
3205 spin_unlock(&t->sighand->siglock);
3206 new_t = kdb_prev_t != t;
3207 kdb_prev_t = t;
3208 if (t->state != TASK_RUNNING && new_t) {
3209 kdb_printf("Process is not RUNNING, sending a signal from "
3210 "kdb risks deadlock\n"
3211 "on the run queue locks. "
3212 "The signal has _not_ been sent.\n"
3213 "Reissue the kill command if you want to risk "
3214 "the deadlock.\n");
3215 return;
3216 }
3217 sig = info->si_signo;
3218 if (send_sig_info(sig, info, t))
3219 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3220 sig, t->pid);
3221 else
3222 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3223}
3224#endif /* CONFIG_KGDB_KDB */
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/proc_fs.h>
26#include <linux/tty.h>
27#include <linux/binfmts.h>
28#include <linux/coredump.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/ptrace.h>
32#include <linux/signal.h>
33#include <linux/signalfd.h>
34#include <linux/ratelimit.h>
35#include <linux/tracehook.h>
36#include <linux/capability.h>
37#include <linux/freezer.h>
38#include <linux/pid_namespace.h>
39#include <linux/nsproxy.h>
40#include <linux/user_namespace.h>
41#include <linux/uprobes.h>
42#include <linux/compat.h>
43#include <linux/cn_proc.h>
44#include <linux/compiler.h>
45#include <linux/posix-timers.h>
46#include <linux/cgroup.h>
47#include <linux/audit.h>
48
49#define CREATE_TRACE_POINTS
50#include <trace/events/signal.h>
51
52#include <asm/param.h>
53#include <linux/uaccess.h>
54#include <asm/unistd.h>
55#include <asm/siginfo.h>
56#include <asm/cacheflush.h>
57
58/*
59 * SLAB caches for signal bits.
60 */
61
62static struct kmem_cache *sigqueue_cachep;
63
64int print_fatal_signals __read_mostly;
65
66static void __user *sig_handler(struct task_struct *t, int sig)
67{
68 return t->sighand->action[sig - 1].sa.sa_handler;
69}
70
71static inline bool sig_handler_ignored(void __user *handler, int sig)
72{
73 /* Is it explicitly or implicitly ignored? */
74 return handler == SIG_IGN ||
75 (handler == SIG_DFL && sig_kernel_ignore(sig));
76}
77
78static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
79{
80 void __user *handler;
81
82 handler = sig_handler(t, sig);
83
84 /* SIGKILL and SIGSTOP may not be sent to the global init */
85 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
86 return true;
87
88 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
89 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
90 return true;
91
92 /* Only allow kernel generated signals to this kthread */
93 if (unlikely((t->flags & PF_KTHREAD) &&
94 (handler == SIG_KTHREAD_KERNEL) && !force))
95 return true;
96
97 return sig_handler_ignored(handler, sig);
98}
99
100static bool sig_ignored(struct task_struct *t, int sig, bool force)
101{
102 /*
103 * Blocked signals are never ignored, since the
104 * signal handler may change by the time it is
105 * unblocked.
106 */
107 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
108 return false;
109
110 /*
111 * Tracers may want to know about even ignored signal unless it
112 * is SIGKILL which can't be reported anyway but can be ignored
113 * by SIGNAL_UNKILLABLE task.
114 */
115 if (t->ptrace && sig != SIGKILL)
116 return false;
117
118 return sig_task_ignored(t, sig, force);
119}
120
121/*
122 * Re-calculate pending state from the set of locally pending
123 * signals, globally pending signals, and blocked signals.
124 */
125static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
126{
127 unsigned long ready;
128 long i;
129
130 switch (_NSIG_WORDS) {
131 default:
132 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
133 ready |= signal->sig[i] &~ blocked->sig[i];
134 break;
135
136 case 4: ready = signal->sig[3] &~ blocked->sig[3];
137 ready |= signal->sig[2] &~ blocked->sig[2];
138 ready |= signal->sig[1] &~ blocked->sig[1];
139 ready |= signal->sig[0] &~ blocked->sig[0];
140 break;
141
142 case 2: ready = signal->sig[1] &~ blocked->sig[1];
143 ready |= signal->sig[0] &~ blocked->sig[0];
144 break;
145
146 case 1: ready = signal->sig[0] &~ blocked->sig[0];
147 }
148 return ready != 0;
149}
150
151#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
152
153static bool recalc_sigpending_tsk(struct task_struct *t)
154{
155 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
156 PENDING(&t->pending, &t->blocked) ||
157 PENDING(&t->signal->shared_pending, &t->blocked) ||
158 cgroup_task_frozen(t)) {
159 set_tsk_thread_flag(t, TIF_SIGPENDING);
160 return true;
161 }
162
163 /*
164 * We must never clear the flag in another thread, or in current
165 * when it's possible the current syscall is returning -ERESTART*.
166 * So we don't clear it here, and only callers who know they should do.
167 */
168 return false;
169}
170
171/*
172 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
173 * This is superfluous when called on current, the wakeup is a harmless no-op.
174 */
175void recalc_sigpending_and_wake(struct task_struct *t)
176{
177 if (recalc_sigpending_tsk(t))
178 signal_wake_up(t, 0);
179}
180
181void recalc_sigpending(void)
182{
183 if (!recalc_sigpending_tsk(current) && !freezing(current))
184 clear_thread_flag(TIF_SIGPENDING);
185
186}
187EXPORT_SYMBOL(recalc_sigpending);
188
189void calculate_sigpending(void)
190{
191 /* Have any signals or users of TIF_SIGPENDING been delayed
192 * until after fork?
193 */
194 spin_lock_irq(¤t->sighand->siglock);
195 set_tsk_thread_flag(current, TIF_SIGPENDING);
196 recalc_sigpending();
197 spin_unlock_irq(¤t->sighand->siglock);
198}
199
200/* Given the mask, find the first available signal that should be serviced. */
201
202#define SYNCHRONOUS_MASK \
203 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
204 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
205
206int next_signal(struct sigpending *pending, sigset_t *mask)
207{
208 unsigned long i, *s, *m, x;
209 int sig = 0;
210
211 s = pending->signal.sig;
212 m = mask->sig;
213
214 /*
215 * Handle the first word specially: it contains the
216 * synchronous signals that need to be dequeued first.
217 */
218 x = *s &~ *m;
219 if (x) {
220 if (x & SYNCHRONOUS_MASK)
221 x &= SYNCHRONOUS_MASK;
222 sig = ffz(~x) + 1;
223 return sig;
224 }
225
226 switch (_NSIG_WORDS) {
227 default:
228 for (i = 1; i < _NSIG_WORDS; ++i) {
229 x = *++s &~ *++m;
230 if (!x)
231 continue;
232 sig = ffz(~x) + i*_NSIG_BPW + 1;
233 break;
234 }
235 break;
236
237 case 2:
238 x = s[1] &~ m[1];
239 if (!x)
240 break;
241 sig = ffz(~x) + _NSIG_BPW + 1;
242 break;
243
244 case 1:
245 /* Nothing to do */
246 break;
247 }
248
249 return sig;
250}
251
252static inline void print_dropped_signal(int sig)
253{
254 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
255
256 if (!print_fatal_signals)
257 return;
258
259 if (!__ratelimit(&ratelimit_state))
260 return;
261
262 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
263 current->comm, current->pid, sig);
264}
265
266/**
267 * task_set_jobctl_pending - set jobctl pending bits
268 * @task: target task
269 * @mask: pending bits to set
270 *
271 * Clear @mask from @task->jobctl. @mask must be subset of
272 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
273 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
274 * cleared. If @task is already being killed or exiting, this function
275 * becomes noop.
276 *
277 * CONTEXT:
278 * Must be called with @task->sighand->siglock held.
279 *
280 * RETURNS:
281 * %true if @mask is set, %false if made noop because @task was dying.
282 */
283bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
284{
285 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
286 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
287 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
288
289 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
290 return false;
291
292 if (mask & JOBCTL_STOP_SIGMASK)
293 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
294
295 task->jobctl |= mask;
296 return true;
297}
298
299/**
300 * task_clear_jobctl_trapping - clear jobctl trapping bit
301 * @task: target task
302 *
303 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
304 * Clear it and wake up the ptracer. Note that we don't need any further
305 * locking. @task->siglock guarantees that @task->parent points to the
306 * ptracer.
307 *
308 * CONTEXT:
309 * Must be called with @task->sighand->siglock held.
310 */
311void task_clear_jobctl_trapping(struct task_struct *task)
312{
313 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
314 task->jobctl &= ~JOBCTL_TRAPPING;
315 smp_mb(); /* advised by wake_up_bit() */
316 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
317 }
318}
319
320/**
321 * task_clear_jobctl_pending - clear jobctl pending bits
322 * @task: target task
323 * @mask: pending bits to clear
324 *
325 * Clear @mask from @task->jobctl. @mask must be subset of
326 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
327 * STOP bits are cleared together.
328 *
329 * If clearing of @mask leaves no stop or trap pending, this function calls
330 * task_clear_jobctl_trapping().
331 *
332 * CONTEXT:
333 * Must be called with @task->sighand->siglock held.
334 */
335void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
336{
337 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
338
339 if (mask & JOBCTL_STOP_PENDING)
340 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
341
342 task->jobctl &= ~mask;
343
344 if (!(task->jobctl & JOBCTL_PENDING_MASK))
345 task_clear_jobctl_trapping(task);
346}
347
348/**
349 * task_participate_group_stop - participate in a group stop
350 * @task: task participating in a group stop
351 *
352 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
353 * Group stop states are cleared and the group stop count is consumed if
354 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
355 * stop, the appropriate `SIGNAL_*` flags are set.
356 *
357 * CONTEXT:
358 * Must be called with @task->sighand->siglock held.
359 *
360 * RETURNS:
361 * %true if group stop completion should be notified to the parent, %false
362 * otherwise.
363 */
364static bool task_participate_group_stop(struct task_struct *task)
365{
366 struct signal_struct *sig = task->signal;
367 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
368
369 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
370
371 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
372
373 if (!consume)
374 return false;
375
376 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
377 sig->group_stop_count--;
378
379 /*
380 * Tell the caller to notify completion iff we are entering into a
381 * fresh group stop. Read comment in do_signal_stop() for details.
382 */
383 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
384 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
385 return true;
386 }
387 return false;
388}
389
390void task_join_group_stop(struct task_struct *task)
391{
392 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
393 struct signal_struct *sig = current->signal;
394
395 if (sig->group_stop_count) {
396 sig->group_stop_count++;
397 mask |= JOBCTL_STOP_CONSUME;
398 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
399 return;
400
401 /* Have the new thread join an on-going signal group stop */
402 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
403}
404
405/*
406 * allocate a new signal queue record
407 * - this may be called without locks if and only if t == current, otherwise an
408 * appropriate lock must be held to stop the target task from exiting
409 */
410static struct sigqueue *
411__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
412 int override_rlimit, const unsigned int sigqueue_flags)
413{
414 struct sigqueue *q = NULL;
415 struct ucounts *ucounts = NULL;
416 long sigpending;
417
418 /*
419 * Protect access to @t credentials. This can go away when all
420 * callers hold rcu read lock.
421 *
422 * NOTE! A pending signal will hold on to the user refcount,
423 * and we get/put the refcount only when the sigpending count
424 * changes from/to zero.
425 */
426 rcu_read_lock();
427 ucounts = task_ucounts(t);
428 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
429 rcu_read_unlock();
430 if (!sigpending)
431 return NULL;
432
433 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
434 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
435 } else {
436 print_dropped_signal(sig);
437 }
438
439 if (unlikely(q == NULL)) {
440 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
441 } else {
442 INIT_LIST_HEAD(&q->list);
443 q->flags = sigqueue_flags;
444 q->ucounts = ucounts;
445 }
446 return q;
447}
448
449static void __sigqueue_free(struct sigqueue *q)
450{
451 if (q->flags & SIGQUEUE_PREALLOC)
452 return;
453 if (q->ucounts) {
454 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
455 q->ucounts = NULL;
456 }
457 kmem_cache_free(sigqueue_cachep, q);
458}
459
460void flush_sigqueue(struct sigpending *queue)
461{
462 struct sigqueue *q;
463
464 sigemptyset(&queue->signal);
465 while (!list_empty(&queue->list)) {
466 q = list_entry(queue->list.next, struct sigqueue , list);
467 list_del_init(&q->list);
468 __sigqueue_free(q);
469 }
470}
471
472/*
473 * Flush all pending signals for this kthread.
474 */
475void flush_signals(struct task_struct *t)
476{
477 unsigned long flags;
478
479 spin_lock_irqsave(&t->sighand->siglock, flags);
480 clear_tsk_thread_flag(t, TIF_SIGPENDING);
481 flush_sigqueue(&t->pending);
482 flush_sigqueue(&t->signal->shared_pending);
483 spin_unlock_irqrestore(&t->sighand->siglock, flags);
484}
485EXPORT_SYMBOL(flush_signals);
486
487#ifdef CONFIG_POSIX_TIMERS
488static void __flush_itimer_signals(struct sigpending *pending)
489{
490 sigset_t signal, retain;
491 struct sigqueue *q, *n;
492
493 signal = pending->signal;
494 sigemptyset(&retain);
495
496 list_for_each_entry_safe(q, n, &pending->list, list) {
497 int sig = q->info.si_signo;
498
499 if (likely(q->info.si_code != SI_TIMER)) {
500 sigaddset(&retain, sig);
501 } else {
502 sigdelset(&signal, sig);
503 list_del_init(&q->list);
504 __sigqueue_free(q);
505 }
506 }
507
508 sigorsets(&pending->signal, &signal, &retain);
509}
510
511void flush_itimer_signals(void)
512{
513 struct task_struct *tsk = current;
514 unsigned long flags;
515
516 spin_lock_irqsave(&tsk->sighand->siglock, flags);
517 __flush_itimer_signals(&tsk->pending);
518 __flush_itimer_signals(&tsk->signal->shared_pending);
519 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
520}
521#endif
522
523void ignore_signals(struct task_struct *t)
524{
525 int i;
526
527 for (i = 0; i < _NSIG; ++i)
528 t->sighand->action[i].sa.sa_handler = SIG_IGN;
529
530 flush_signals(t);
531}
532
533/*
534 * Flush all handlers for a task.
535 */
536
537void
538flush_signal_handlers(struct task_struct *t, int force_default)
539{
540 int i;
541 struct k_sigaction *ka = &t->sighand->action[0];
542 for (i = _NSIG ; i != 0 ; i--) {
543 if (force_default || ka->sa.sa_handler != SIG_IGN)
544 ka->sa.sa_handler = SIG_DFL;
545 ka->sa.sa_flags = 0;
546#ifdef __ARCH_HAS_SA_RESTORER
547 ka->sa.sa_restorer = NULL;
548#endif
549 sigemptyset(&ka->sa.sa_mask);
550 ka++;
551 }
552}
553
554bool unhandled_signal(struct task_struct *tsk, int sig)
555{
556 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
557 if (is_global_init(tsk))
558 return true;
559
560 if (handler != SIG_IGN && handler != SIG_DFL)
561 return false;
562
563 /* if ptraced, let the tracer determine */
564 return !tsk->ptrace;
565}
566
567static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
568 bool *resched_timer)
569{
570 struct sigqueue *q, *first = NULL;
571
572 /*
573 * Collect the siginfo appropriate to this signal. Check if
574 * there is another siginfo for the same signal.
575 */
576 list_for_each_entry(q, &list->list, list) {
577 if (q->info.si_signo == sig) {
578 if (first)
579 goto still_pending;
580 first = q;
581 }
582 }
583
584 sigdelset(&list->signal, sig);
585
586 if (first) {
587still_pending:
588 list_del_init(&first->list);
589 copy_siginfo(info, &first->info);
590
591 *resched_timer =
592 (first->flags & SIGQUEUE_PREALLOC) &&
593 (info->si_code == SI_TIMER) &&
594 (info->si_sys_private);
595
596 __sigqueue_free(first);
597 } else {
598 /*
599 * Ok, it wasn't in the queue. This must be
600 * a fast-pathed signal or we must have been
601 * out of queue space. So zero out the info.
602 */
603 clear_siginfo(info);
604 info->si_signo = sig;
605 info->si_errno = 0;
606 info->si_code = SI_USER;
607 info->si_pid = 0;
608 info->si_uid = 0;
609 }
610}
611
612static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
613 kernel_siginfo_t *info, bool *resched_timer)
614{
615 int sig = next_signal(pending, mask);
616
617 if (sig)
618 collect_signal(sig, pending, info, resched_timer);
619 return sig;
620}
621
622/*
623 * Dequeue a signal and return the element to the caller, which is
624 * expected to free it.
625 *
626 * All callers have to hold the siglock.
627 */
628int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
629{
630 bool resched_timer = false;
631 int signr;
632
633 /* We only dequeue private signals from ourselves, we don't let
634 * signalfd steal them
635 */
636 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
637 if (!signr) {
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 set_tsk_thread_flag(t, TIF_SIGPENDING);
762 /*
763 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
764 * case. We don't check t->state here because there is a race with it
765 * executing another processor and just now entering stopped state.
766 * By using wake_up_state, we ensure the process will wake up and
767 * handle its death signal.
768 */
769 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
770 kick_process(t);
771}
772
773/*
774 * Remove signals in mask from the pending set and queue.
775 * Returns 1 if any signals were found.
776 *
777 * All callers must be holding the siglock.
778 */
779static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
780{
781 struct sigqueue *q, *n;
782 sigset_t m;
783
784 sigandsets(&m, mask, &s->signal);
785 if (sigisemptyset(&m))
786 return;
787
788 sigandnsets(&s->signal, &s->signal, mask);
789 list_for_each_entry_safe(q, n, &s->list, list) {
790 if (sigismember(mask, q->info.si_signo)) {
791 list_del_init(&q->list);
792 __sigqueue_free(q);
793 }
794 }
795}
796
797static inline int is_si_special(const struct kernel_siginfo *info)
798{
799 return info <= SEND_SIG_PRIV;
800}
801
802static inline bool si_fromuser(const struct kernel_siginfo *info)
803{
804 return info == SEND_SIG_NOINFO ||
805 (!is_si_special(info) && SI_FROMUSER(info));
806}
807
808/*
809 * called with RCU read lock from check_kill_permission()
810 */
811static bool kill_ok_by_cred(struct task_struct *t)
812{
813 const struct cred *cred = current_cred();
814 const struct cred *tcred = __task_cred(t);
815
816 return uid_eq(cred->euid, tcred->suid) ||
817 uid_eq(cred->euid, tcred->uid) ||
818 uid_eq(cred->uid, tcred->suid) ||
819 uid_eq(cred->uid, tcred->uid) ||
820 ns_capable(tcred->user_ns, CAP_KILL);
821}
822
823/*
824 * Bad permissions for sending the signal
825 * - the caller must hold the RCU read lock
826 */
827static int check_kill_permission(int sig, struct kernel_siginfo *info,
828 struct task_struct *t)
829{
830 struct pid *sid;
831 int error;
832
833 if (!valid_signal(sig))
834 return -EINVAL;
835
836 if (!si_fromuser(info))
837 return 0;
838
839 error = audit_signal_info(sig, t); /* Let audit system see the signal */
840 if (error)
841 return error;
842
843 if (!same_thread_group(current, t) &&
844 !kill_ok_by_cred(t)) {
845 switch (sig) {
846 case SIGCONT:
847 sid = task_session(t);
848 /*
849 * We don't return the error if sid == NULL. The
850 * task was unhashed, the caller must notice this.
851 */
852 if (!sid || sid == task_session(current))
853 break;
854 fallthrough;
855 default:
856 return -EPERM;
857 }
858 }
859
860 return security_task_kill(t, info, sig, NULL);
861}
862
863/**
864 * ptrace_trap_notify - schedule trap to notify ptracer
865 * @t: tracee wanting to notify tracer
866 *
867 * This function schedules sticky ptrace trap which is cleared on the next
868 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
869 * ptracer.
870 *
871 * If @t is running, STOP trap will be taken. If trapped for STOP and
872 * ptracer is listening for events, tracee is woken up so that it can
873 * re-trap for the new event. If trapped otherwise, STOP trap will be
874 * eventually taken without returning to userland after the existing traps
875 * are finished by PTRACE_CONT.
876 *
877 * CONTEXT:
878 * Must be called with @task->sighand->siglock held.
879 */
880static void ptrace_trap_notify(struct task_struct *t)
881{
882 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
883 assert_spin_locked(&t->sighand->siglock);
884
885 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
886 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
887}
888
889/*
890 * Handle magic process-wide effects of stop/continue signals. Unlike
891 * the signal actions, these happen immediately at signal-generation
892 * time regardless of blocking, ignoring, or handling. This does the
893 * actual continuing for SIGCONT, but not the actual stopping for stop
894 * signals. The process stop is done as a signal action for SIG_DFL.
895 *
896 * Returns true if the signal should be actually delivered, otherwise
897 * it should be dropped.
898 */
899static bool prepare_signal(int sig, struct task_struct *p, bool force)
900{
901 struct signal_struct *signal = p->signal;
902 struct task_struct *t;
903 sigset_t flush;
904
905 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
906 if (!(signal->flags & SIGNAL_GROUP_EXIT))
907 return sig == SIGKILL;
908 /*
909 * The process is in the middle of dying, nothing to do.
910 */
911 } else if (sig_kernel_stop(sig)) {
912 /*
913 * This is a stop signal. Remove SIGCONT from all queues.
914 */
915 siginitset(&flush, sigmask(SIGCONT));
916 flush_sigqueue_mask(&flush, &signal->shared_pending);
917 for_each_thread(p, t)
918 flush_sigqueue_mask(&flush, &t->pending);
919 } else if (sig == SIGCONT) {
920 unsigned int why;
921 /*
922 * Remove all stop signals from all queues, wake all threads.
923 */
924 siginitset(&flush, SIG_KERNEL_STOP_MASK);
925 flush_sigqueue_mask(&flush, &signal->shared_pending);
926 for_each_thread(p, t) {
927 flush_sigqueue_mask(&flush, &t->pending);
928 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
929 if (likely(!(t->ptrace & PT_SEIZED)))
930 wake_up_state(t, __TASK_STOPPED);
931 else
932 ptrace_trap_notify(t);
933 }
934
935 /*
936 * Notify the parent with CLD_CONTINUED if we were stopped.
937 *
938 * If we were in the middle of a group stop, we pretend it
939 * was already finished, and then continued. Since SIGCHLD
940 * doesn't queue we report only CLD_STOPPED, as if the next
941 * CLD_CONTINUED was dropped.
942 */
943 why = 0;
944 if (signal->flags & SIGNAL_STOP_STOPPED)
945 why |= SIGNAL_CLD_CONTINUED;
946 else if (signal->group_stop_count)
947 why |= SIGNAL_CLD_STOPPED;
948
949 if (why) {
950 /*
951 * The first thread which returns from do_signal_stop()
952 * will take ->siglock, notice SIGNAL_CLD_MASK, and
953 * notify its parent. See get_signal().
954 */
955 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
956 signal->group_stop_count = 0;
957 signal->group_exit_code = 0;
958 }
959 }
960
961 return !sig_ignored(p, sig, force);
962}
963
964/*
965 * Test if P wants to take SIG. After we've checked all threads with this,
966 * it's equivalent to finding no threads not blocking SIG. Any threads not
967 * blocking SIG were ruled out because they are not running and already
968 * have pending signals. Such threads will dequeue from the shared queue
969 * as soon as they're available, so putting the signal on the shared queue
970 * will be equivalent to sending it to one such thread.
971 */
972static inline bool wants_signal(int sig, struct task_struct *p)
973{
974 if (sigismember(&p->blocked, sig))
975 return false;
976
977 if (p->flags & PF_EXITING)
978 return false;
979
980 if (sig == SIGKILL)
981 return true;
982
983 if (task_is_stopped_or_traced(p))
984 return false;
985
986 return task_curr(p) || !task_sigpending(p);
987}
988
989static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
990{
991 struct signal_struct *signal = p->signal;
992 struct task_struct *t;
993
994 /*
995 * Now find a thread we can wake up to take the signal off the queue.
996 *
997 * If the main thread wants the signal, it gets first crack.
998 * Probably the least surprising to the average bear.
999 */
1000 if (wants_signal(sig, p))
1001 t = p;
1002 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1003 /*
1004 * There is just one thread and it does not need to be woken.
1005 * It will dequeue unblocked signals before it runs again.
1006 */
1007 return;
1008 else {
1009 /*
1010 * Otherwise try to find a suitable thread.
1011 */
1012 t = signal->curr_target;
1013 while (!wants_signal(sig, t)) {
1014 t = next_thread(t);
1015 if (t == signal->curr_target)
1016 /*
1017 * No thread needs to be woken.
1018 * Any eligible threads will see
1019 * the signal in the queue soon.
1020 */
1021 return;
1022 }
1023 signal->curr_target = t;
1024 }
1025
1026 /*
1027 * Found a killable thread. If the signal will be fatal,
1028 * then start taking the whole group down immediately.
1029 */
1030 if (sig_fatal(p, sig) &&
1031 !(signal->flags & SIGNAL_GROUP_EXIT) &&
1032 !sigismember(&t->real_blocked, sig) &&
1033 (sig == SIGKILL || !p->ptrace)) {
1034 /*
1035 * This signal will be fatal to the whole group.
1036 */
1037 if (!sig_kernel_coredump(sig)) {
1038 /*
1039 * Start a group exit and wake everybody up.
1040 * This way we don't have other threads
1041 * running and doing things after a slower
1042 * thread has the fatal signal pending.
1043 */
1044 signal->flags = SIGNAL_GROUP_EXIT;
1045 signal->group_exit_code = sig;
1046 signal->group_stop_count = 0;
1047 t = p;
1048 do {
1049 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1050 sigaddset(&t->pending.signal, SIGKILL);
1051 signal_wake_up(t, 1);
1052 } while_each_thread(p, t);
1053 return;
1054 }
1055 }
1056
1057 /*
1058 * The signal is already in the shared-pending queue.
1059 * Tell the chosen thread to wake up and dequeue it.
1060 */
1061 signal_wake_up(t, sig == SIGKILL);
1062 return;
1063}
1064
1065static inline bool legacy_queue(struct sigpending *signals, int sig)
1066{
1067 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1068}
1069
1070static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1071 enum pid_type type, bool force)
1072{
1073 struct sigpending *pending;
1074 struct sigqueue *q;
1075 int override_rlimit;
1076 int ret = 0, result;
1077
1078 assert_spin_locked(&t->sighand->siglock);
1079
1080 result = TRACE_SIGNAL_IGNORED;
1081 if (!prepare_signal(sig, t, force))
1082 goto ret;
1083
1084 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1085 /*
1086 * Short-circuit ignored signals and support queuing
1087 * exactly one non-rt signal, so that we can get more
1088 * detailed information about the cause of the signal.
1089 */
1090 result = TRACE_SIGNAL_ALREADY_PENDING;
1091 if (legacy_queue(pending, sig))
1092 goto ret;
1093
1094 result = TRACE_SIGNAL_DELIVERED;
1095 /*
1096 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1097 */
1098 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1099 goto out_set;
1100
1101 /*
1102 * Real-time signals must be queued if sent by sigqueue, or
1103 * some other real-time mechanism. It is implementation
1104 * defined whether kill() does so. We attempt to do so, on
1105 * the principle of least surprise, but since kill is not
1106 * allowed to fail with EAGAIN when low on memory we just
1107 * make sure at least one signal gets delivered and don't
1108 * pass on the info struct.
1109 */
1110 if (sig < SIGRTMIN)
1111 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1112 else
1113 override_rlimit = 0;
1114
1115 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1116
1117 if (q) {
1118 list_add_tail(&q->list, &pending->list);
1119 switch ((unsigned long) info) {
1120 case (unsigned long) SEND_SIG_NOINFO:
1121 clear_siginfo(&q->info);
1122 q->info.si_signo = sig;
1123 q->info.si_errno = 0;
1124 q->info.si_code = SI_USER;
1125 q->info.si_pid = task_tgid_nr_ns(current,
1126 task_active_pid_ns(t));
1127 rcu_read_lock();
1128 q->info.si_uid =
1129 from_kuid_munged(task_cred_xxx(t, user_ns),
1130 current_uid());
1131 rcu_read_unlock();
1132 break;
1133 case (unsigned long) SEND_SIG_PRIV:
1134 clear_siginfo(&q->info);
1135 q->info.si_signo = sig;
1136 q->info.si_errno = 0;
1137 q->info.si_code = SI_KERNEL;
1138 q->info.si_pid = 0;
1139 q->info.si_uid = 0;
1140 break;
1141 default:
1142 copy_siginfo(&q->info, info);
1143 break;
1144 }
1145 } else if (!is_si_special(info) &&
1146 sig >= SIGRTMIN && info->si_code != SI_USER) {
1147 /*
1148 * Queue overflow, abort. We may abort if the
1149 * signal was rt and sent by user using something
1150 * other than kill().
1151 */
1152 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1153 ret = -EAGAIN;
1154 goto ret;
1155 } else {
1156 /*
1157 * This is a silent loss of information. We still
1158 * send the signal, but the *info bits are lost.
1159 */
1160 result = TRACE_SIGNAL_LOSE_INFO;
1161 }
1162
1163out_set:
1164 signalfd_notify(t, sig);
1165 sigaddset(&pending->signal, sig);
1166
1167 /* Let multiprocess signals appear after on-going forks */
1168 if (type > PIDTYPE_TGID) {
1169 struct multiprocess_signals *delayed;
1170 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1171 sigset_t *signal = &delayed->signal;
1172 /* Can't queue both a stop and a continue signal */
1173 if (sig == SIGCONT)
1174 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1175 else if (sig_kernel_stop(sig))
1176 sigdelset(signal, SIGCONT);
1177 sigaddset(signal, sig);
1178 }
1179 }
1180
1181 complete_signal(sig, t, type);
1182ret:
1183 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1184 return ret;
1185}
1186
1187static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1188{
1189 bool ret = false;
1190 switch (siginfo_layout(info->si_signo, info->si_code)) {
1191 case SIL_KILL:
1192 case SIL_CHLD:
1193 case SIL_RT:
1194 ret = true;
1195 break;
1196 case SIL_TIMER:
1197 case SIL_POLL:
1198 case SIL_FAULT:
1199 case SIL_FAULT_TRAPNO:
1200 case SIL_FAULT_MCEERR:
1201 case SIL_FAULT_BNDERR:
1202 case SIL_FAULT_PKUERR:
1203 case SIL_PERF_EVENT:
1204 case SIL_SYS:
1205 ret = false;
1206 break;
1207 }
1208 return ret;
1209}
1210
1211static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1212 enum pid_type type)
1213{
1214 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1215 bool force = false;
1216
1217 if (info == SEND_SIG_NOINFO) {
1218 /* Force if sent from an ancestor pid namespace */
1219 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1220 } else if (info == SEND_SIG_PRIV) {
1221 /* Don't ignore kernel generated signals */
1222 force = true;
1223 } else if (has_si_pid_and_uid(info)) {
1224 /* SIGKILL and SIGSTOP is special or has ids */
1225 struct user_namespace *t_user_ns;
1226
1227 rcu_read_lock();
1228 t_user_ns = task_cred_xxx(t, user_ns);
1229 if (current_user_ns() != t_user_ns) {
1230 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1231 info->si_uid = from_kuid_munged(t_user_ns, uid);
1232 }
1233 rcu_read_unlock();
1234
1235 /* A kernel generated signal? */
1236 force = (info->si_code == SI_KERNEL);
1237
1238 /* From an ancestor pid namespace? */
1239 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1240 info->si_pid = 0;
1241 force = true;
1242 }
1243 }
1244 return __send_signal(sig, info, t, type, force);
1245}
1246
1247static void print_fatal_signal(int signr)
1248{
1249 struct pt_regs *regs = signal_pt_regs();
1250 pr_info("potentially unexpected fatal signal %d.\n", signr);
1251
1252#if defined(__i386__) && !defined(__arch_um__)
1253 pr_info("code at %08lx: ", regs->ip);
1254 {
1255 int i;
1256 for (i = 0; i < 16; i++) {
1257 unsigned char insn;
1258
1259 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1260 break;
1261 pr_cont("%02x ", insn);
1262 }
1263 }
1264 pr_cont("\n");
1265#endif
1266 preempt_disable();
1267 show_regs(regs);
1268 preempt_enable();
1269}
1270
1271static int __init setup_print_fatal_signals(char *str)
1272{
1273 get_option (&str, &print_fatal_signals);
1274
1275 return 1;
1276}
1277
1278__setup("print-fatal-signals=", setup_print_fatal_signals);
1279
1280int
1281__group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1282{
1283 return send_signal(sig, info, p, PIDTYPE_TGID);
1284}
1285
1286int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1287 enum pid_type type)
1288{
1289 unsigned long flags;
1290 int ret = -ESRCH;
1291
1292 if (lock_task_sighand(p, &flags)) {
1293 ret = send_signal(sig, info, p, type);
1294 unlock_task_sighand(p, &flags);
1295 }
1296
1297 return ret;
1298}
1299
1300/*
1301 * Force a signal that the process can't ignore: if necessary
1302 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1303 *
1304 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1305 * since we do not want to have a signal handler that was blocked
1306 * be invoked when user space had explicitly blocked it.
1307 *
1308 * We don't want to have recursive SIGSEGV's etc, for example,
1309 * that is why we also clear SIGNAL_UNKILLABLE.
1310 */
1311static int
1312force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
1313{
1314 unsigned long int flags;
1315 int ret, blocked, ignored;
1316 struct k_sigaction *action;
1317 int sig = info->si_signo;
1318
1319 spin_lock_irqsave(&t->sighand->siglock, flags);
1320 action = &t->sighand->action[sig-1];
1321 ignored = action->sa.sa_handler == SIG_IGN;
1322 blocked = sigismember(&t->blocked, sig);
1323 if (blocked || ignored) {
1324 action->sa.sa_handler = SIG_DFL;
1325 if (blocked) {
1326 sigdelset(&t->blocked, sig);
1327 recalc_sigpending_and_wake(t);
1328 }
1329 }
1330 /*
1331 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1332 * debugging to leave init killable.
1333 */
1334 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1335 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1336 ret = send_signal(sig, info, t, PIDTYPE_PID);
1337 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1338
1339 return ret;
1340}
1341
1342int force_sig_info(struct kernel_siginfo *info)
1343{
1344 return force_sig_info_to_task(info, current);
1345}
1346
1347/*
1348 * Nuke all other threads in the group.
1349 */
1350int zap_other_threads(struct task_struct *p)
1351{
1352 struct task_struct *t = p;
1353 int count = 0;
1354
1355 p->signal->group_stop_count = 0;
1356
1357 while_each_thread(p, t) {
1358 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1359 count++;
1360
1361 /* Don't bother with already dead threads */
1362 if (t->exit_state)
1363 continue;
1364 sigaddset(&t->pending.signal, SIGKILL);
1365 signal_wake_up(t, 1);
1366 }
1367
1368 return count;
1369}
1370
1371struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1372 unsigned long *flags)
1373{
1374 struct sighand_struct *sighand;
1375
1376 rcu_read_lock();
1377 for (;;) {
1378 sighand = rcu_dereference(tsk->sighand);
1379 if (unlikely(sighand == NULL))
1380 break;
1381
1382 /*
1383 * This sighand can be already freed and even reused, but
1384 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1385 * initializes ->siglock: this slab can't go away, it has
1386 * the same object type, ->siglock can't be reinitialized.
1387 *
1388 * We need to ensure that tsk->sighand is still the same
1389 * after we take the lock, we can race with de_thread() or
1390 * __exit_signal(). In the latter case the next iteration
1391 * must see ->sighand == NULL.
1392 */
1393 spin_lock_irqsave(&sighand->siglock, *flags);
1394 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1395 break;
1396 spin_unlock_irqrestore(&sighand->siglock, *flags);
1397 }
1398 rcu_read_unlock();
1399
1400 return sighand;
1401}
1402
1403/*
1404 * send signal info to all the members of a group
1405 */
1406int group_send_sig_info(int sig, struct kernel_siginfo *info,
1407 struct task_struct *p, enum pid_type type)
1408{
1409 int ret;
1410
1411 rcu_read_lock();
1412 ret = check_kill_permission(sig, info, p);
1413 rcu_read_unlock();
1414
1415 if (!ret && sig)
1416 ret = do_send_sig_info(sig, info, p, type);
1417
1418 return ret;
1419}
1420
1421/*
1422 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1423 * control characters do (^C, ^Z etc)
1424 * - the caller must hold at least a readlock on tasklist_lock
1425 */
1426int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1427{
1428 struct task_struct *p = NULL;
1429 int retval, success;
1430
1431 success = 0;
1432 retval = -ESRCH;
1433 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1434 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1435 success |= !err;
1436 retval = err;
1437 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1438 return success ? 0 : retval;
1439}
1440
1441int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1442{
1443 int error = -ESRCH;
1444 struct task_struct *p;
1445
1446 for (;;) {
1447 rcu_read_lock();
1448 p = pid_task(pid, PIDTYPE_PID);
1449 if (p)
1450 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1451 rcu_read_unlock();
1452 if (likely(!p || error != -ESRCH))
1453 return error;
1454
1455 /*
1456 * The task was unhashed in between, try again. If it
1457 * is dead, pid_task() will return NULL, if we race with
1458 * de_thread() it will find the new leader.
1459 */
1460 }
1461}
1462
1463static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1464{
1465 int error;
1466 rcu_read_lock();
1467 error = kill_pid_info(sig, info, find_vpid(pid));
1468 rcu_read_unlock();
1469 return error;
1470}
1471
1472static inline bool kill_as_cred_perm(const struct cred *cred,
1473 struct task_struct *target)
1474{
1475 const struct cred *pcred = __task_cred(target);
1476
1477 return uid_eq(cred->euid, pcred->suid) ||
1478 uid_eq(cred->euid, pcred->uid) ||
1479 uid_eq(cred->uid, pcred->suid) ||
1480 uid_eq(cred->uid, pcred->uid);
1481}
1482
1483/*
1484 * The usb asyncio usage of siginfo is wrong. The glibc support
1485 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1486 * AKA after the generic fields:
1487 * kernel_pid_t si_pid;
1488 * kernel_uid32_t si_uid;
1489 * sigval_t si_value;
1490 *
1491 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1492 * after the generic fields is:
1493 * void __user *si_addr;
1494 *
1495 * This is a practical problem when there is a 64bit big endian kernel
1496 * and a 32bit userspace. As the 32bit address will encoded in the low
1497 * 32bits of the pointer. Those low 32bits will be stored at higher
1498 * address than appear in a 32 bit pointer. So userspace will not
1499 * see the address it was expecting for it's completions.
1500 *
1501 * There is nothing in the encoding that can allow
1502 * copy_siginfo_to_user32 to detect this confusion of formats, so
1503 * handle this by requiring the caller of kill_pid_usb_asyncio to
1504 * notice when this situration takes place and to store the 32bit
1505 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1506 * parameter.
1507 */
1508int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1509 struct pid *pid, const struct cred *cred)
1510{
1511 struct kernel_siginfo info;
1512 struct task_struct *p;
1513 unsigned long flags;
1514 int ret = -EINVAL;
1515
1516 if (!valid_signal(sig))
1517 return ret;
1518
1519 clear_siginfo(&info);
1520 info.si_signo = sig;
1521 info.si_errno = errno;
1522 info.si_code = SI_ASYNCIO;
1523 *((sigval_t *)&info.si_pid) = addr;
1524
1525 rcu_read_lock();
1526 p = pid_task(pid, PIDTYPE_PID);
1527 if (!p) {
1528 ret = -ESRCH;
1529 goto out_unlock;
1530 }
1531 if (!kill_as_cred_perm(cred, p)) {
1532 ret = -EPERM;
1533 goto out_unlock;
1534 }
1535 ret = security_task_kill(p, &info, sig, cred);
1536 if (ret)
1537 goto out_unlock;
1538
1539 if (sig) {
1540 if (lock_task_sighand(p, &flags)) {
1541 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1542 unlock_task_sighand(p, &flags);
1543 } else
1544 ret = -ESRCH;
1545 }
1546out_unlock:
1547 rcu_read_unlock();
1548 return ret;
1549}
1550EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1551
1552/*
1553 * kill_something_info() interprets pid in interesting ways just like kill(2).
1554 *
1555 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1556 * is probably wrong. Should make it like BSD or SYSV.
1557 */
1558
1559static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1560{
1561 int ret;
1562
1563 if (pid > 0)
1564 return kill_proc_info(sig, info, pid);
1565
1566 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1567 if (pid == INT_MIN)
1568 return -ESRCH;
1569
1570 read_lock(&tasklist_lock);
1571 if (pid != -1) {
1572 ret = __kill_pgrp_info(sig, info,
1573 pid ? find_vpid(-pid) : task_pgrp(current));
1574 } else {
1575 int retval = 0, count = 0;
1576 struct task_struct * p;
1577
1578 for_each_process(p) {
1579 if (task_pid_vnr(p) > 1 &&
1580 !same_thread_group(p, current)) {
1581 int err = group_send_sig_info(sig, info, p,
1582 PIDTYPE_MAX);
1583 ++count;
1584 if (err != -EPERM)
1585 retval = err;
1586 }
1587 }
1588 ret = count ? retval : -ESRCH;
1589 }
1590 read_unlock(&tasklist_lock);
1591
1592 return ret;
1593}
1594
1595/*
1596 * These are for backward compatibility with the rest of the kernel source.
1597 */
1598
1599int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1600{
1601 /*
1602 * Make sure legacy kernel users don't send in bad values
1603 * (normal paths check this in check_kill_permission).
1604 */
1605 if (!valid_signal(sig))
1606 return -EINVAL;
1607
1608 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1609}
1610EXPORT_SYMBOL(send_sig_info);
1611
1612#define __si_special(priv) \
1613 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1614
1615int
1616send_sig(int sig, struct task_struct *p, int priv)
1617{
1618 return send_sig_info(sig, __si_special(priv), p);
1619}
1620EXPORT_SYMBOL(send_sig);
1621
1622void force_sig(int sig)
1623{
1624 struct kernel_siginfo info;
1625
1626 clear_siginfo(&info);
1627 info.si_signo = sig;
1628 info.si_errno = 0;
1629 info.si_code = SI_KERNEL;
1630 info.si_pid = 0;
1631 info.si_uid = 0;
1632 force_sig_info(&info);
1633}
1634EXPORT_SYMBOL(force_sig);
1635
1636/*
1637 * When things go south during signal handling, we
1638 * will force a SIGSEGV. And if the signal that caused
1639 * the problem was already a SIGSEGV, we'll want to
1640 * make sure we don't even try to deliver the signal..
1641 */
1642void force_sigsegv(int sig)
1643{
1644 struct task_struct *p = current;
1645
1646 if (sig == SIGSEGV) {
1647 unsigned long flags;
1648 spin_lock_irqsave(&p->sighand->siglock, flags);
1649 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1650 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1651 }
1652 force_sig(SIGSEGV);
1653}
1654
1655int force_sig_fault_to_task(int sig, int code, void __user *addr
1656 ___ARCH_SI_TRAPNO(int trapno)
1657 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1658 , struct task_struct *t)
1659{
1660 struct kernel_siginfo info;
1661
1662 clear_siginfo(&info);
1663 info.si_signo = sig;
1664 info.si_errno = 0;
1665 info.si_code = code;
1666 info.si_addr = addr;
1667#ifdef __ARCH_SI_TRAPNO
1668 info.si_trapno = trapno;
1669#endif
1670#ifdef __ia64__
1671 info.si_imm = imm;
1672 info.si_flags = flags;
1673 info.si_isr = isr;
1674#endif
1675 return force_sig_info_to_task(&info, t);
1676}
1677
1678int force_sig_fault(int sig, int code, void __user *addr
1679 ___ARCH_SI_TRAPNO(int trapno)
1680 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1681{
1682 return force_sig_fault_to_task(sig, code, addr
1683 ___ARCH_SI_TRAPNO(trapno)
1684 ___ARCH_SI_IA64(imm, flags, isr), current);
1685}
1686
1687int send_sig_fault(int sig, int code, void __user *addr
1688 ___ARCH_SI_TRAPNO(int trapno)
1689 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1690 , struct task_struct *t)
1691{
1692 struct kernel_siginfo info;
1693
1694 clear_siginfo(&info);
1695 info.si_signo = sig;
1696 info.si_errno = 0;
1697 info.si_code = code;
1698 info.si_addr = addr;
1699#ifdef __ARCH_SI_TRAPNO
1700 info.si_trapno = trapno;
1701#endif
1702#ifdef __ia64__
1703 info.si_imm = imm;
1704 info.si_flags = flags;
1705 info.si_isr = isr;
1706#endif
1707 return send_sig_info(info.si_signo, &info, t);
1708}
1709
1710int force_sig_mceerr(int code, void __user *addr, short lsb)
1711{
1712 struct kernel_siginfo info;
1713
1714 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1715 clear_siginfo(&info);
1716 info.si_signo = SIGBUS;
1717 info.si_errno = 0;
1718 info.si_code = code;
1719 info.si_addr = addr;
1720 info.si_addr_lsb = lsb;
1721 return force_sig_info(&info);
1722}
1723
1724int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1725{
1726 struct kernel_siginfo info;
1727
1728 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1729 clear_siginfo(&info);
1730 info.si_signo = SIGBUS;
1731 info.si_errno = 0;
1732 info.si_code = code;
1733 info.si_addr = addr;
1734 info.si_addr_lsb = lsb;
1735 return send_sig_info(info.si_signo, &info, t);
1736}
1737EXPORT_SYMBOL(send_sig_mceerr);
1738
1739int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1740{
1741 struct kernel_siginfo info;
1742
1743 clear_siginfo(&info);
1744 info.si_signo = SIGSEGV;
1745 info.si_errno = 0;
1746 info.si_code = SEGV_BNDERR;
1747 info.si_addr = addr;
1748 info.si_lower = lower;
1749 info.si_upper = upper;
1750 return force_sig_info(&info);
1751}
1752
1753#ifdef SEGV_PKUERR
1754int force_sig_pkuerr(void __user *addr, u32 pkey)
1755{
1756 struct kernel_siginfo info;
1757
1758 clear_siginfo(&info);
1759 info.si_signo = SIGSEGV;
1760 info.si_errno = 0;
1761 info.si_code = SEGV_PKUERR;
1762 info.si_addr = addr;
1763 info.si_pkey = pkey;
1764 return force_sig_info(&info);
1765}
1766#endif
1767
1768int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
1769{
1770 struct kernel_siginfo info;
1771
1772 clear_siginfo(&info);
1773 info.si_signo = SIGTRAP;
1774 info.si_errno = 0;
1775 info.si_code = TRAP_PERF;
1776 info.si_addr = addr;
1777 info.si_perf_data = sig_data;
1778 info.si_perf_type = type;
1779
1780 return force_sig_info(&info);
1781}
1782
1783/* For the crazy architectures that include trap information in
1784 * the errno field, instead of an actual errno value.
1785 */
1786int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1787{
1788 struct kernel_siginfo info;
1789
1790 clear_siginfo(&info);
1791 info.si_signo = SIGTRAP;
1792 info.si_errno = errno;
1793 info.si_code = TRAP_HWBKPT;
1794 info.si_addr = addr;
1795 return force_sig_info(&info);
1796}
1797
1798int kill_pgrp(struct pid *pid, int sig, int priv)
1799{
1800 int ret;
1801
1802 read_lock(&tasklist_lock);
1803 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1804 read_unlock(&tasklist_lock);
1805
1806 return ret;
1807}
1808EXPORT_SYMBOL(kill_pgrp);
1809
1810int kill_pid(struct pid *pid, int sig, int priv)
1811{
1812 return kill_pid_info(sig, __si_special(priv), pid);
1813}
1814EXPORT_SYMBOL(kill_pid);
1815
1816/*
1817 * These functions support sending signals using preallocated sigqueue
1818 * structures. This is needed "because realtime applications cannot
1819 * afford to lose notifications of asynchronous events, like timer
1820 * expirations or I/O completions". In the case of POSIX Timers
1821 * we allocate the sigqueue structure from the timer_create. If this
1822 * allocation fails we are able to report the failure to the application
1823 * with an EAGAIN error.
1824 */
1825struct sigqueue *sigqueue_alloc(void)
1826{
1827 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1828}
1829
1830void sigqueue_free(struct sigqueue *q)
1831{
1832 unsigned long flags;
1833 spinlock_t *lock = ¤t->sighand->siglock;
1834
1835 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1836 /*
1837 * We must hold ->siglock while testing q->list
1838 * to serialize with collect_signal() or with
1839 * __exit_signal()->flush_sigqueue().
1840 */
1841 spin_lock_irqsave(lock, flags);
1842 q->flags &= ~SIGQUEUE_PREALLOC;
1843 /*
1844 * If it is queued it will be freed when dequeued,
1845 * like the "regular" sigqueue.
1846 */
1847 if (!list_empty(&q->list))
1848 q = NULL;
1849 spin_unlock_irqrestore(lock, flags);
1850
1851 if (q)
1852 __sigqueue_free(q);
1853}
1854
1855int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1856{
1857 int sig = q->info.si_signo;
1858 struct sigpending *pending;
1859 struct task_struct *t;
1860 unsigned long flags;
1861 int ret, result;
1862
1863 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1864
1865 ret = -1;
1866 rcu_read_lock();
1867 t = pid_task(pid, type);
1868 if (!t || !likely(lock_task_sighand(t, &flags)))
1869 goto ret;
1870
1871 ret = 1; /* the signal is ignored */
1872 result = TRACE_SIGNAL_IGNORED;
1873 if (!prepare_signal(sig, t, false))
1874 goto out;
1875
1876 ret = 0;
1877 if (unlikely(!list_empty(&q->list))) {
1878 /*
1879 * If an SI_TIMER entry is already queue just increment
1880 * the overrun count.
1881 */
1882 BUG_ON(q->info.si_code != SI_TIMER);
1883 q->info.si_overrun++;
1884 result = TRACE_SIGNAL_ALREADY_PENDING;
1885 goto out;
1886 }
1887 q->info.si_overrun = 0;
1888
1889 signalfd_notify(t, sig);
1890 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1891 list_add_tail(&q->list, &pending->list);
1892 sigaddset(&pending->signal, sig);
1893 complete_signal(sig, t, type);
1894 result = TRACE_SIGNAL_DELIVERED;
1895out:
1896 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1897 unlock_task_sighand(t, &flags);
1898ret:
1899 rcu_read_unlock();
1900 return ret;
1901}
1902
1903static void do_notify_pidfd(struct task_struct *task)
1904{
1905 struct pid *pid;
1906
1907 WARN_ON(task->exit_state == 0);
1908 pid = task_pid(task);
1909 wake_up_all(&pid->wait_pidfd);
1910}
1911
1912/*
1913 * Let a parent know about the death of a child.
1914 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1915 *
1916 * Returns true if our parent ignored us and so we've switched to
1917 * self-reaping.
1918 */
1919bool do_notify_parent(struct task_struct *tsk, int sig)
1920{
1921 struct kernel_siginfo info;
1922 unsigned long flags;
1923 struct sighand_struct *psig;
1924 bool autoreap = false;
1925 u64 utime, stime;
1926
1927 BUG_ON(sig == -1);
1928
1929 /* do_notify_parent_cldstop should have been called instead. */
1930 BUG_ON(task_is_stopped_or_traced(tsk));
1931
1932 BUG_ON(!tsk->ptrace &&
1933 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1934
1935 /* Wake up all pidfd waiters */
1936 do_notify_pidfd(tsk);
1937
1938 if (sig != SIGCHLD) {
1939 /*
1940 * This is only possible if parent == real_parent.
1941 * Check if it has changed security domain.
1942 */
1943 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
1944 sig = SIGCHLD;
1945 }
1946
1947 clear_siginfo(&info);
1948 info.si_signo = sig;
1949 info.si_errno = 0;
1950 /*
1951 * We are under tasklist_lock here so our parent is tied to
1952 * us and cannot change.
1953 *
1954 * task_active_pid_ns will always return the same pid namespace
1955 * until a task passes through release_task.
1956 *
1957 * write_lock() currently calls preempt_disable() which is the
1958 * same as rcu_read_lock(), but according to Oleg, this is not
1959 * correct to rely on this
1960 */
1961 rcu_read_lock();
1962 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1963 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1964 task_uid(tsk));
1965 rcu_read_unlock();
1966
1967 task_cputime(tsk, &utime, &stime);
1968 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1969 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1970
1971 info.si_status = tsk->exit_code & 0x7f;
1972 if (tsk->exit_code & 0x80)
1973 info.si_code = CLD_DUMPED;
1974 else if (tsk->exit_code & 0x7f)
1975 info.si_code = CLD_KILLED;
1976 else {
1977 info.si_code = CLD_EXITED;
1978 info.si_status = tsk->exit_code >> 8;
1979 }
1980
1981 psig = tsk->parent->sighand;
1982 spin_lock_irqsave(&psig->siglock, flags);
1983 if (!tsk->ptrace && sig == SIGCHLD &&
1984 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1985 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1986 /*
1987 * We are exiting and our parent doesn't care. POSIX.1
1988 * defines special semantics for setting SIGCHLD to SIG_IGN
1989 * or setting the SA_NOCLDWAIT flag: we should be reaped
1990 * automatically and not left for our parent's wait4 call.
1991 * Rather than having the parent do it as a magic kind of
1992 * signal handler, we just set this to tell do_exit that we
1993 * can be cleaned up without becoming a zombie. Note that
1994 * we still call __wake_up_parent in this case, because a
1995 * blocked sys_wait4 might now return -ECHILD.
1996 *
1997 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1998 * is implementation-defined: we do (if you don't want
1999 * it, just use SIG_IGN instead).
2000 */
2001 autoreap = true;
2002 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2003 sig = 0;
2004 }
2005 /*
2006 * Send with __send_signal as si_pid and si_uid are in the
2007 * parent's namespaces.
2008 */
2009 if (valid_signal(sig) && sig)
2010 __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2011 __wake_up_parent(tsk, tsk->parent);
2012 spin_unlock_irqrestore(&psig->siglock, flags);
2013
2014 return autoreap;
2015}
2016
2017/**
2018 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2019 * @tsk: task reporting the state change
2020 * @for_ptracer: the notification is for ptracer
2021 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2022 *
2023 * Notify @tsk's parent that the stopped/continued state has changed. If
2024 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2025 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2026 *
2027 * CONTEXT:
2028 * Must be called with tasklist_lock at least read locked.
2029 */
2030static void do_notify_parent_cldstop(struct task_struct *tsk,
2031 bool for_ptracer, int why)
2032{
2033 struct kernel_siginfo info;
2034 unsigned long flags;
2035 struct task_struct *parent;
2036 struct sighand_struct *sighand;
2037 u64 utime, stime;
2038
2039 if (for_ptracer) {
2040 parent = tsk->parent;
2041 } else {
2042 tsk = tsk->group_leader;
2043 parent = tsk->real_parent;
2044 }
2045
2046 clear_siginfo(&info);
2047 info.si_signo = SIGCHLD;
2048 info.si_errno = 0;
2049 /*
2050 * see comment in do_notify_parent() about the following 4 lines
2051 */
2052 rcu_read_lock();
2053 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2054 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2055 rcu_read_unlock();
2056
2057 task_cputime(tsk, &utime, &stime);
2058 info.si_utime = nsec_to_clock_t(utime);
2059 info.si_stime = nsec_to_clock_t(stime);
2060
2061 info.si_code = why;
2062 switch (why) {
2063 case CLD_CONTINUED:
2064 info.si_status = SIGCONT;
2065 break;
2066 case CLD_STOPPED:
2067 info.si_status = tsk->signal->group_exit_code & 0x7f;
2068 break;
2069 case CLD_TRAPPED:
2070 info.si_status = tsk->exit_code & 0x7f;
2071 break;
2072 default:
2073 BUG();
2074 }
2075
2076 sighand = parent->sighand;
2077 spin_lock_irqsave(&sighand->siglock, flags);
2078 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2079 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2080 __group_send_sig_info(SIGCHLD, &info, parent);
2081 /*
2082 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2083 */
2084 __wake_up_parent(tsk, parent);
2085 spin_unlock_irqrestore(&sighand->siglock, flags);
2086}
2087
2088static inline bool may_ptrace_stop(void)
2089{
2090 if (!likely(current->ptrace))
2091 return false;
2092 /*
2093 * Are we in the middle of do_coredump?
2094 * If so and our tracer is also part of the coredump stopping
2095 * is a deadlock situation, and pointless because our tracer
2096 * is dead so don't allow us to stop.
2097 * If SIGKILL was already sent before the caller unlocked
2098 * ->siglock we must see ->core_state != NULL. Otherwise it
2099 * is safe to enter schedule().
2100 *
2101 * This is almost outdated, a task with the pending SIGKILL can't
2102 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
2103 * after SIGKILL was already dequeued.
2104 */
2105 if (unlikely(current->mm->core_state) &&
2106 unlikely(current->mm == current->parent->mm))
2107 return false;
2108
2109 return true;
2110}
2111
2112/*
2113 * Return non-zero if there is a SIGKILL that should be waking us up.
2114 * Called with the siglock held.
2115 */
2116static bool sigkill_pending(struct task_struct *tsk)
2117{
2118 return sigismember(&tsk->pending.signal, SIGKILL) ||
2119 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
2120}
2121
2122/*
2123 * This must be called with current->sighand->siglock held.
2124 *
2125 * This should be the path for all ptrace stops.
2126 * We always set current->last_siginfo while stopped here.
2127 * That makes it a way to test a stopped process for
2128 * being ptrace-stopped vs being job-control-stopped.
2129 *
2130 * If we actually decide not to stop at all because the tracer
2131 * is gone, we keep current->exit_code unless clear_code.
2132 */
2133static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
2134 __releases(¤t->sighand->siglock)
2135 __acquires(¤t->sighand->siglock)
2136{
2137 bool gstop_done = false;
2138
2139 if (arch_ptrace_stop_needed(exit_code, info)) {
2140 /*
2141 * The arch code has something special to do before a
2142 * ptrace stop. This is allowed to block, e.g. for faults
2143 * on user stack pages. We can't keep the siglock while
2144 * calling arch_ptrace_stop, so we must release it now.
2145 * To preserve proper semantics, we must do this before
2146 * any signal bookkeeping like checking group_stop_count.
2147 * Meanwhile, a SIGKILL could come in before we retake the
2148 * siglock. That must prevent us from sleeping in TASK_TRACED.
2149 * So after regaining the lock, we must check for SIGKILL.
2150 */
2151 spin_unlock_irq(¤t->sighand->siglock);
2152 arch_ptrace_stop(exit_code, info);
2153 spin_lock_irq(¤t->sighand->siglock);
2154 if (sigkill_pending(current))
2155 return;
2156 }
2157
2158 set_special_state(TASK_TRACED);
2159
2160 /*
2161 * We're committing to trapping. TRACED should be visible before
2162 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2163 * Also, transition to TRACED and updates to ->jobctl should be
2164 * atomic with respect to siglock and should be done after the arch
2165 * hook as siglock is released and regrabbed across it.
2166 *
2167 * TRACER TRACEE
2168 *
2169 * ptrace_attach()
2170 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2171 * do_wait()
2172 * set_current_state() smp_wmb();
2173 * ptrace_do_wait()
2174 * wait_task_stopped()
2175 * task_stopped_code()
2176 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2177 */
2178 smp_wmb();
2179
2180 current->last_siginfo = info;
2181 current->exit_code = exit_code;
2182
2183 /*
2184 * If @why is CLD_STOPPED, we're trapping to participate in a group
2185 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2186 * across siglock relocks since INTERRUPT was scheduled, PENDING
2187 * could be clear now. We act as if SIGCONT is received after
2188 * TASK_TRACED is entered - ignore it.
2189 */
2190 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2191 gstop_done = task_participate_group_stop(current);
2192
2193 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2194 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2195 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2196 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2197
2198 /* entering a trap, clear TRAPPING */
2199 task_clear_jobctl_trapping(current);
2200
2201 spin_unlock_irq(¤t->sighand->siglock);
2202 read_lock(&tasklist_lock);
2203 if (may_ptrace_stop()) {
2204 /*
2205 * Notify parents of the stop.
2206 *
2207 * While ptraced, there are two parents - the ptracer and
2208 * the real_parent of the group_leader. The ptracer should
2209 * know about every stop while the real parent is only
2210 * interested in the completion of group stop. The states
2211 * for the two don't interact with each other. Notify
2212 * separately unless they're gonna be duplicates.
2213 */
2214 do_notify_parent_cldstop(current, true, why);
2215 if (gstop_done && ptrace_reparented(current))
2216 do_notify_parent_cldstop(current, false, why);
2217
2218 /*
2219 * Don't want to allow preemption here, because
2220 * sys_ptrace() needs this task to be inactive.
2221 *
2222 * XXX: implement read_unlock_no_resched().
2223 */
2224 preempt_disable();
2225 read_unlock(&tasklist_lock);
2226 cgroup_enter_frozen();
2227 preempt_enable_no_resched();
2228 freezable_schedule();
2229 cgroup_leave_frozen(true);
2230 } else {
2231 /*
2232 * By the time we got the lock, our tracer went away.
2233 * Don't drop the lock yet, another tracer may come.
2234 *
2235 * If @gstop_done, the ptracer went away between group stop
2236 * completion and here. During detach, it would have set
2237 * JOBCTL_STOP_PENDING on us and we'll re-enter
2238 * TASK_STOPPED in do_signal_stop() on return, so notifying
2239 * the real parent of the group stop completion is enough.
2240 */
2241 if (gstop_done)
2242 do_notify_parent_cldstop(current, false, why);
2243
2244 /* tasklist protects us from ptrace_freeze_traced() */
2245 __set_current_state(TASK_RUNNING);
2246 if (clear_code)
2247 current->exit_code = 0;
2248 read_unlock(&tasklist_lock);
2249 }
2250
2251 /*
2252 * We are back. Now reacquire the siglock before touching
2253 * last_siginfo, so that we are sure to have synchronized with
2254 * any signal-sending on another CPU that wants to examine it.
2255 */
2256 spin_lock_irq(¤t->sighand->siglock);
2257 current->last_siginfo = NULL;
2258
2259 /* LISTENING can be set only during STOP traps, clear it */
2260 current->jobctl &= ~JOBCTL_LISTENING;
2261
2262 /*
2263 * Queued signals ignored us while we were stopped for tracing.
2264 * So check for any that we should take before resuming user mode.
2265 * This sets TIF_SIGPENDING, but never clears it.
2266 */
2267 recalc_sigpending_tsk(current);
2268}
2269
2270static void ptrace_do_notify(int signr, int exit_code, int why)
2271{
2272 kernel_siginfo_t info;
2273
2274 clear_siginfo(&info);
2275 info.si_signo = signr;
2276 info.si_code = exit_code;
2277 info.si_pid = task_pid_vnr(current);
2278 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2279
2280 /* Let the debugger run. */
2281 ptrace_stop(exit_code, why, 1, &info);
2282}
2283
2284void ptrace_notify(int exit_code)
2285{
2286 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2287 if (unlikely(current->task_works))
2288 task_work_run();
2289
2290 spin_lock_irq(¤t->sighand->siglock);
2291 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2292 spin_unlock_irq(¤t->sighand->siglock);
2293}
2294
2295/**
2296 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2297 * @signr: signr causing group stop if initiating
2298 *
2299 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2300 * and participate in it. If already set, participate in the existing
2301 * group stop. If participated in a group stop (and thus slept), %true is
2302 * returned with siglock released.
2303 *
2304 * If ptraced, this function doesn't handle stop itself. Instead,
2305 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2306 * untouched. The caller must ensure that INTERRUPT trap handling takes
2307 * places afterwards.
2308 *
2309 * CONTEXT:
2310 * Must be called with @current->sighand->siglock held, which is released
2311 * on %true return.
2312 *
2313 * RETURNS:
2314 * %false if group stop is already cancelled or ptrace trap is scheduled.
2315 * %true if participated in group stop.
2316 */
2317static bool do_signal_stop(int signr)
2318 __releases(¤t->sighand->siglock)
2319{
2320 struct signal_struct *sig = current->signal;
2321
2322 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2323 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2324 struct task_struct *t;
2325
2326 /* signr will be recorded in task->jobctl for retries */
2327 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2328
2329 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2330 unlikely(signal_group_exit(sig)))
2331 return false;
2332 /*
2333 * There is no group stop already in progress. We must
2334 * initiate one now.
2335 *
2336 * While ptraced, a task may be resumed while group stop is
2337 * still in effect and then receive a stop signal and
2338 * initiate another group stop. This deviates from the
2339 * usual behavior as two consecutive stop signals can't
2340 * cause two group stops when !ptraced. That is why we
2341 * also check !task_is_stopped(t) below.
2342 *
2343 * The condition can be distinguished by testing whether
2344 * SIGNAL_STOP_STOPPED is already set. Don't generate
2345 * group_exit_code in such case.
2346 *
2347 * This is not necessary for SIGNAL_STOP_CONTINUED because
2348 * an intervening stop signal is required to cause two
2349 * continued events regardless of ptrace.
2350 */
2351 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2352 sig->group_exit_code = signr;
2353
2354 sig->group_stop_count = 0;
2355
2356 if (task_set_jobctl_pending(current, signr | gstop))
2357 sig->group_stop_count++;
2358
2359 t = current;
2360 while_each_thread(current, t) {
2361 /*
2362 * Setting state to TASK_STOPPED for a group
2363 * stop is always done with the siglock held,
2364 * so this check has no races.
2365 */
2366 if (!task_is_stopped(t) &&
2367 task_set_jobctl_pending(t, signr | gstop)) {
2368 sig->group_stop_count++;
2369 if (likely(!(t->ptrace & PT_SEIZED)))
2370 signal_wake_up(t, 0);
2371 else
2372 ptrace_trap_notify(t);
2373 }
2374 }
2375 }
2376
2377 if (likely(!current->ptrace)) {
2378 int notify = 0;
2379
2380 /*
2381 * If there are no other threads in the group, or if there
2382 * is a group stop in progress and we are the last to stop,
2383 * report to the parent.
2384 */
2385 if (task_participate_group_stop(current))
2386 notify = CLD_STOPPED;
2387
2388 set_special_state(TASK_STOPPED);
2389 spin_unlock_irq(¤t->sighand->siglock);
2390
2391 /*
2392 * Notify the parent of the group stop completion. Because
2393 * we're not holding either the siglock or tasklist_lock
2394 * here, ptracer may attach inbetween; however, this is for
2395 * group stop and should always be delivered to the real
2396 * parent of the group leader. The new ptracer will get
2397 * its notification when this task transitions into
2398 * TASK_TRACED.
2399 */
2400 if (notify) {
2401 read_lock(&tasklist_lock);
2402 do_notify_parent_cldstop(current, false, notify);
2403 read_unlock(&tasklist_lock);
2404 }
2405
2406 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2407 cgroup_enter_frozen();
2408 freezable_schedule();
2409 return true;
2410 } else {
2411 /*
2412 * While ptraced, group stop is handled by STOP trap.
2413 * Schedule it and let the caller deal with it.
2414 */
2415 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2416 return false;
2417 }
2418}
2419
2420/**
2421 * do_jobctl_trap - take care of ptrace jobctl traps
2422 *
2423 * When PT_SEIZED, it's used for both group stop and explicit
2424 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2425 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2426 * the stop signal; otherwise, %SIGTRAP.
2427 *
2428 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2429 * number as exit_code and no siginfo.
2430 *
2431 * CONTEXT:
2432 * Must be called with @current->sighand->siglock held, which may be
2433 * released and re-acquired before returning with intervening sleep.
2434 */
2435static void do_jobctl_trap(void)
2436{
2437 struct signal_struct *signal = current->signal;
2438 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2439
2440 if (current->ptrace & PT_SEIZED) {
2441 if (!signal->group_stop_count &&
2442 !(signal->flags & SIGNAL_STOP_STOPPED))
2443 signr = SIGTRAP;
2444 WARN_ON_ONCE(!signr);
2445 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2446 CLD_STOPPED);
2447 } else {
2448 WARN_ON_ONCE(!signr);
2449 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2450 current->exit_code = 0;
2451 }
2452}
2453
2454/**
2455 * do_freezer_trap - handle the freezer jobctl trap
2456 *
2457 * Puts the task into frozen state, if only the task is not about to quit.
2458 * In this case it drops JOBCTL_TRAP_FREEZE.
2459 *
2460 * CONTEXT:
2461 * Must be called with @current->sighand->siglock held,
2462 * which is always released before returning.
2463 */
2464static void do_freezer_trap(void)
2465 __releases(¤t->sighand->siglock)
2466{
2467 /*
2468 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2469 * let's make another loop to give it a chance to be handled.
2470 * In any case, we'll return back.
2471 */
2472 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2473 JOBCTL_TRAP_FREEZE) {
2474 spin_unlock_irq(¤t->sighand->siglock);
2475 return;
2476 }
2477
2478 /*
2479 * Now we're sure that there is no pending fatal signal and no
2480 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2481 * immediately (if there is a non-fatal signal pending), and
2482 * put the task into sleep.
2483 */
2484 __set_current_state(TASK_INTERRUPTIBLE);
2485 clear_thread_flag(TIF_SIGPENDING);
2486 spin_unlock_irq(¤t->sighand->siglock);
2487 cgroup_enter_frozen();
2488 freezable_schedule();
2489}
2490
2491static int ptrace_signal(int signr, kernel_siginfo_t *info)
2492{
2493 /*
2494 * We do not check sig_kernel_stop(signr) but set this marker
2495 * unconditionally because we do not know whether debugger will
2496 * change signr. This flag has no meaning unless we are going
2497 * to stop after return from ptrace_stop(). In this case it will
2498 * be checked in do_signal_stop(), we should only stop if it was
2499 * not cleared by SIGCONT while we were sleeping. See also the
2500 * comment in dequeue_signal().
2501 */
2502 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2503 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2504
2505 /* We're back. Did the debugger cancel the sig? */
2506 signr = current->exit_code;
2507 if (signr == 0)
2508 return signr;
2509
2510 current->exit_code = 0;
2511
2512 /*
2513 * Update the siginfo structure if the signal has
2514 * changed. If the debugger wanted something
2515 * specific in the siginfo structure then it should
2516 * have updated *info via PTRACE_SETSIGINFO.
2517 */
2518 if (signr != info->si_signo) {
2519 clear_siginfo(info);
2520 info->si_signo = signr;
2521 info->si_errno = 0;
2522 info->si_code = SI_USER;
2523 rcu_read_lock();
2524 info->si_pid = task_pid_vnr(current->parent);
2525 info->si_uid = from_kuid_munged(current_user_ns(),
2526 task_uid(current->parent));
2527 rcu_read_unlock();
2528 }
2529
2530 /* If the (new) signal is now blocked, requeue it. */
2531 if (sigismember(¤t->blocked, signr)) {
2532 send_signal(signr, info, current, PIDTYPE_PID);
2533 signr = 0;
2534 }
2535
2536 return signr;
2537}
2538
2539static void hide_si_addr_tag_bits(struct ksignal *ksig)
2540{
2541 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2542 case SIL_FAULT:
2543 case SIL_FAULT_TRAPNO:
2544 case SIL_FAULT_MCEERR:
2545 case SIL_FAULT_BNDERR:
2546 case SIL_FAULT_PKUERR:
2547 case SIL_PERF_EVENT:
2548 ksig->info.si_addr = arch_untagged_si_addr(
2549 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2550 break;
2551 case SIL_KILL:
2552 case SIL_TIMER:
2553 case SIL_POLL:
2554 case SIL_CHLD:
2555 case SIL_RT:
2556 case SIL_SYS:
2557 break;
2558 }
2559}
2560
2561bool get_signal(struct ksignal *ksig)
2562{
2563 struct sighand_struct *sighand = current->sighand;
2564 struct signal_struct *signal = current->signal;
2565 int signr;
2566
2567 if (unlikely(current->task_works))
2568 task_work_run();
2569
2570 /*
2571 * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so
2572 * that the arch handlers don't all have to do it. If we get here
2573 * without TIF_SIGPENDING, just exit after running signal work.
2574 */
2575 if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
2576 if (test_thread_flag(TIF_NOTIFY_SIGNAL))
2577 tracehook_notify_signal();
2578 if (!task_sigpending(current))
2579 return false;
2580 }
2581
2582 if (unlikely(uprobe_deny_signal()))
2583 return false;
2584
2585 /*
2586 * Do this once, we can't return to user-mode if freezing() == T.
2587 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2588 * thus do not need another check after return.
2589 */
2590 try_to_freeze();
2591
2592relock:
2593 spin_lock_irq(&sighand->siglock);
2594
2595 /*
2596 * Every stopped thread goes here after wakeup. Check to see if
2597 * we should notify the parent, prepare_signal(SIGCONT) encodes
2598 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2599 */
2600 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2601 int why;
2602
2603 if (signal->flags & SIGNAL_CLD_CONTINUED)
2604 why = CLD_CONTINUED;
2605 else
2606 why = CLD_STOPPED;
2607
2608 signal->flags &= ~SIGNAL_CLD_MASK;
2609
2610 spin_unlock_irq(&sighand->siglock);
2611
2612 /*
2613 * Notify the parent that we're continuing. This event is
2614 * always per-process and doesn't make whole lot of sense
2615 * for ptracers, who shouldn't consume the state via
2616 * wait(2) either, but, for backward compatibility, notify
2617 * the ptracer of the group leader too unless it's gonna be
2618 * a duplicate.
2619 */
2620 read_lock(&tasklist_lock);
2621 do_notify_parent_cldstop(current, false, why);
2622
2623 if (ptrace_reparented(current->group_leader))
2624 do_notify_parent_cldstop(current->group_leader,
2625 true, why);
2626 read_unlock(&tasklist_lock);
2627
2628 goto relock;
2629 }
2630
2631 /* Has this task already been marked for death? */
2632 if (signal_group_exit(signal)) {
2633 ksig->info.si_signo = signr = SIGKILL;
2634 sigdelset(¤t->pending.signal, SIGKILL);
2635 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2636 &sighand->action[SIGKILL - 1]);
2637 recalc_sigpending();
2638 goto fatal;
2639 }
2640
2641 for (;;) {
2642 struct k_sigaction *ka;
2643
2644 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2645 do_signal_stop(0))
2646 goto relock;
2647
2648 if (unlikely(current->jobctl &
2649 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2650 if (current->jobctl & JOBCTL_TRAP_MASK) {
2651 do_jobctl_trap();
2652 spin_unlock_irq(&sighand->siglock);
2653 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2654 do_freezer_trap();
2655
2656 goto relock;
2657 }
2658
2659 /*
2660 * If the task is leaving the frozen state, let's update
2661 * cgroup counters and reset the frozen bit.
2662 */
2663 if (unlikely(cgroup_task_frozen(current))) {
2664 spin_unlock_irq(&sighand->siglock);
2665 cgroup_leave_frozen(false);
2666 goto relock;
2667 }
2668
2669 /*
2670 * Signals generated by the execution of an instruction
2671 * need to be delivered before any other pending signals
2672 * so that the instruction pointer in the signal stack
2673 * frame points to the faulting instruction.
2674 */
2675 signr = dequeue_synchronous_signal(&ksig->info);
2676 if (!signr)
2677 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2678
2679 if (!signr)
2680 break; /* will return 0 */
2681
2682 if (unlikely(current->ptrace) && signr != SIGKILL) {
2683 signr = ptrace_signal(signr, &ksig->info);
2684 if (!signr)
2685 continue;
2686 }
2687
2688 ka = &sighand->action[signr-1];
2689
2690 /* Trace actually delivered signals. */
2691 trace_signal_deliver(signr, &ksig->info, ka);
2692
2693 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2694 continue;
2695 if (ka->sa.sa_handler != SIG_DFL) {
2696 /* Run the handler. */
2697 ksig->ka = *ka;
2698
2699 if (ka->sa.sa_flags & SA_ONESHOT)
2700 ka->sa.sa_handler = SIG_DFL;
2701
2702 break; /* will return non-zero "signr" value */
2703 }
2704
2705 /*
2706 * Now we are doing the default action for this signal.
2707 */
2708 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2709 continue;
2710
2711 /*
2712 * Global init gets no signals it doesn't want.
2713 * Container-init gets no signals it doesn't want from same
2714 * container.
2715 *
2716 * Note that if global/container-init sees a sig_kernel_only()
2717 * signal here, the signal must have been generated internally
2718 * or must have come from an ancestor namespace. In either
2719 * case, the signal cannot be dropped.
2720 */
2721 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2722 !sig_kernel_only(signr))
2723 continue;
2724
2725 if (sig_kernel_stop(signr)) {
2726 /*
2727 * The default action is to stop all threads in
2728 * the thread group. The job control signals
2729 * do nothing in an orphaned pgrp, but SIGSTOP
2730 * always works. Note that siglock needs to be
2731 * dropped during the call to is_orphaned_pgrp()
2732 * because of lock ordering with tasklist_lock.
2733 * This allows an intervening SIGCONT to be posted.
2734 * We need to check for that and bail out if necessary.
2735 */
2736 if (signr != SIGSTOP) {
2737 spin_unlock_irq(&sighand->siglock);
2738
2739 /* signals can be posted during this window */
2740
2741 if (is_current_pgrp_orphaned())
2742 goto relock;
2743
2744 spin_lock_irq(&sighand->siglock);
2745 }
2746
2747 if (likely(do_signal_stop(ksig->info.si_signo))) {
2748 /* It released the siglock. */
2749 goto relock;
2750 }
2751
2752 /*
2753 * We didn't actually stop, due to a race
2754 * with SIGCONT or something like that.
2755 */
2756 continue;
2757 }
2758
2759 fatal:
2760 spin_unlock_irq(&sighand->siglock);
2761 if (unlikely(cgroup_task_frozen(current)))
2762 cgroup_leave_frozen(true);
2763
2764 /*
2765 * Anything else is fatal, maybe with a core dump.
2766 */
2767 current->flags |= PF_SIGNALED;
2768
2769 if (sig_kernel_coredump(signr)) {
2770 if (print_fatal_signals)
2771 print_fatal_signal(ksig->info.si_signo);
2772 proc_coredump_connector(current);
2773 /*
2774 * If it was able to dump core, this kills all
2775 * other threads in the group and synchronizes with
2776 * their demise. If we lost the race with another
2777 * thread getting here, it set group_exit_code
2778 * first and our do_group_exit call below will use
2779 * that value and ignore the one we pass it.
2780 */
2781 do_coredump(&ksig->info);
2782 }
2783
2784 /*
2785 * PF_IO_WORKER threads will catch and exit on fatal signals
2786 * themselves. They have cleanup that must be performed, so
2787 * we cannot call do_exit() on their behalf.
2788 */
2789 if (current->flags & PF_IO_WORKER)
2790 goto out;
2791
2792 /*
2793 * Death signals, no core dump.
2794 */
2795 do_group_exit(ksig->info.si_signo);
2796 /* NOTREACHED */
2797 }
2798 spin_unlock_irq(&sighand->siglock);
2799out:
2800 ksig->sig = signr;
2801
2802 if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2803 hide_si_addr_tag_bits(ksig);
2804
2805 return ksig->sig > 0;
2806}
2807
2808/**
2809 * signal_delivered -
2810 * @ksig: kernel signal struct
2811 * @stepping: nonzero if debugger single-step or block-step in use
2812 *
2813 * This function should be called when a signal has successfully been
2814 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2815 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2816 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2817 */
2818static void signal_delivered(struct ksignal *ksig, int stepping)
2819{
2820 sigset_t blocked;
2821
2822 /* A signal was successfully delivered, and the
2823 saved sigmask was stored on the signal frame,
2824 and will be restored by sigreturn. So we can
2825 simply clear the restore sigmask flag. */
2826 clear_restore_sigmask();
2827
2828 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2829 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2830 sigaddset(&blocked, ksig->sig);
2831 set_current_blocked(&blocked);
2832 if (current->sas_ss_flags & SS_AUTODISARM)
2833 sas_ss_reset(current);
2834 tracehook_signal_handler(stepping);
2835}
2836
2837void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2838{
2839 if (failed)
2840 force_sigsegv(ksig->sig);
2841 else
2842 signal_delivered(ksig, stepping);
2843}
2844
2845/*
2846 * It could be that complete_signal() picked us to notify about the
2847 * group-wide signal. Other threads should be notified now to take
2848 * the shared signals in @which since we will not.
2849 */
2850static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2851{
2852 sigset_t retarget;
2853 struct task_struct *t;
2854
2855 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2856 if (sigisemptyset(&retarget))
2857 return;
2858
2859 t = tsk;
2860 while_each_thread(tsk, t) {
2861 if (t->flags & PF_EXITING)
2862 continue;
2863
2864 if (!has_pending_signals(&retarget, &t->blocked))
2865 continue;
2866 /* Remove the signals this thread can handle. */
2867 sigandsets(&retarget, &retarget, &t->blocked);
2868
2869 if (!task_sigpending(t))
2870 signal_wake_up(t, 0);
2871
2872 if (sigisemptyset(&retarget))
2873 break;
2874 }
2875}
2876
2877void exit_signals(struct task_struct *tsk)
2878{
2879 int group_stop = 0;
2880 sigset_t unblocked;
2881
2882 /*
2883 * @tsk is about to have PF_EXITING set - lock out users which
2884 * expect stable threadgroup.
2885 */
2886 cgroup_threadgroup_change_begin(tsk);
2887
2888 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2889 tsk->flags |= PF_EXITING;
2890 cgroup_threadgroup_change_end(tsk);
2891 return;
2892 }
2893
2894 spin_lock_irq(&tsk->sighand->siglock);
2895 /*
2896 * From now this task is not visible for group-wide signals,
2897 * see wants_signal(), do_signal_stop().
2898 */
2899 tsk->flags |= PF_EXITING;
2900
2901 cgroup_threadgroup_change_end(tsk);
2902
2903 if (!task_sigpending(tsk))
2904 goto out;
2905
2906 unblocked = tsk->blocked;
2907 signotset(&unblocked);
2908 retarget_shared_pending(tsk, &unblocked);
2909
2910 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2911 task_participate_group_stop(tsk))
2912 group_stop = CLD_STOPPED;
2913out:
2914 spin_unlock_irq(&tsk->sighand->siglock);
2915
2916 /*
2917 * If group stop has completed, deliver the notification. This
2918 * should always go to the real parent of the group leader.
2919 */
2920 if (unlikely(group_stop)) {
2921 read_lock(&tasklist_lock);
2922 do_notify_parent_cldstop(tsk, false, group_stop);
2923 read_unlock(&tasklist_lock);
2924 }
2925}
2926
2927/*
2928 * System call entry points.
2929 */
2930
2931/**
2932 * sys_restart_syscall - restart a system call
2933 */
2934SYSCALL_DEFINE0(restart_syscall)
2935{
2936 struct restart_block *restart = ¤t->restart_block;
2937 return restart->fn(restart);
2938}
2939
2940long do_no_restart_syscall(struct restart_block *param)
2941{
2942 return -EINTR;
2943}
2944
2945static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2946{
2947 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
2948 sigset_t newblocked;
2949 /* A set of now blocked but previously unblocked signals. */
2950 sigandnsets(&newblocked, newset, ¤t->blocked);
2951 retarget_shared_pending(tsk, &newblocked);
2952 }
2953 tsk->blocked = *newset;
2954 recalc_sigpending();
2955}
2956
2957/**
2958 * set_current_blocked - change current->blocked mask
2959 * @newset: new mask
2960 *
2961 * It is wrong to change ->blocked directly, this helper should be used
2962 * to ensure the process can't miss a shared signal we are going to block.
2963 */
2964void set_current_blocked(sigset_t *newset)
2965{
2966 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2967 __set_current_blocked(newset);
2968}
2969
2970void __set_current_blocked(const sigset_t *newset)
2971{
2972 struct task_struct *tsk = current;
2973
2974 /*
2975 * In case the signal mask hasn't changed, there is nothing we need
2976 * to do. The current->blocked shouldn't be modified by other task.
2977 */
2978 if (sigequalsets(&tsk->blocked, newset))
2979 return;
2980
2981 spin_lock_irq(&tsk->sighand->siglock);
2982 __set_task_blocked(tsk, newset);
2983 spin_unlock_irq(&tsk->sighand->siglock);
2984}
2985
2986/*
2987 * This is also useful for kernel threads that want to temporarily
2988 * (or permanently) block certain signals.
2989 *
2990 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2991 * interface happily blocks "unblockable" signals like SIGKILL
2992 * and friends.
2993 */
2994int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2995{
2996 struct task_struct *tsk = current;
2997 sigset_t newset;
2998
2999 /* Lockless, only current can change ->blocked, never from irq */
3000 if (oldset)
3001 *oldset = tsk->blocked;
3002
3003 switch (how) {
3004 case SIG_BLOCK:
3005 sigorsets(&newset, &tsk->blocked, set);
3006 break;
3007 case SIG_UNBLOCK:
3008 sigandnsets(&newset, &tsk->blocked, set);
3009 break;
3010 case SIG_SETMASK:
3011 newset = *set;
3012 break;
3013 default:
3014 return -EINVAL;
3015 }
3016
3017 __set_current_blocked(&newset);
3018 return 0;
3019}
3020EXPORT_SYMBOL(sigprocmask);
3021
3022/*
3023 * The api helps set app-provided sigmasks.
3024 *
3025 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3026 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3027 *
3028 * Note that it does set_restore_sigmask() in advance, so it must be always
3029 * paired with restore_saved_sigmask_unless() before return from syscall.
3030 */
3031int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3032{
3033 sigset_t kmask;
3034
3035 if (!umask)
3036 return 0;
3037 if (sigsetsize != sizeof(sigset_t))
3038 return -EINVAL;
3039 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3040 return -EFAULT;
3041
3042 set_restore_sigmask();
3043 current->saved_sigmask = current->blocked;
3044 set_current_blocked(&kmask);
3045
3046 return 0;
3047}
3048
3049#ifdef CONFIG_COMPAT
3050int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3051 size_t sigsetsize)
3052{
3053 sigset_t kmask;
3054
3055 if (!umask)
3056 return 0;
3057 if (sigsetsize != sizeof(compat_sigset_t))
3058 return -EINVAL;
3059 if (get_compat_sigset(&kmask, umask))
3060 return -EFAULT;
3061
3062 set_restore_sigmask();
3063 current->saved_sigmask = current->blocked;
3064 set_current_blocked(&kmask);
3065
3066 return 0;
3067}
3068#endif
3069
3070/**
3071 * sys_rt_sigprocmask - change the list of currently blocked signals
3072 * @how: whether to add, remove, or set signals
3073 * @nset: stores pending signals
3074 * @oset: previous value of signal mask if non-null
3075 * @sigsetsize: size of sigset_t type
3076 */
3077SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3078 sigset_t __user *, oset, size_t, sigsetsize)
3079{
3080 sigset_t old_set, new_set;
3081 int error;
3082
3083 /* XXX: Don't preclude handling different sized sigset_t's. */
3084 if (sigsetsize != sizeof(sigset_t))
3085 return -EINVAL;
3086
3087 old_set = current->blocked;
3088
3089 if (nset) {
3090 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3091 return -EFAULT;
3092 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3093
3094 error = sigprocmask(how, &new_set, NULL);
3095 if (error)
3096 return error;
3097 }
3098
3099 if (oset) {
3100 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3101 return -EFAULT;
3102 }
3103
3104 return 0;
3105}
3106
3107#ifdef CONFIG_COMPAT
3108COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3109 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3110{
3111 sigset_t old_set = current->blocked;
3112
3113 /* XXX: Don't preclude handling different sized sigset_t's. */
3114 if (sigsetsize != sizeof(sigset_t))
3115 return -EINVAL;
3116
3117 if (nset) {
3118 sigset_t new_set;
3119 int error;
3120 if (get_compat_sigset(&new_set, nset))
3121 return -EFAULT;
3122 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3123
3124 error = sigprocmask(how, &new_set, NULL);
3125 if (error)
3126 return error;
3127 }
3128 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3129}
3130#endif
3131
3132static void do_sigpending(sigset_t *set)
3133{
3134 spin_lock_irq(¤t->sighand->siglock);
3135 sigorsets(set, ¤t->pending.signal,
3136 ¤t->signal->shared_pending.signal);
3137 spin_unlock_irq(¤t->sighand->siglock);
3138
3139 /* Outside the lock because only this thread touches it. */
3140 sigandsets(set, ¤t->blocked, set);
3141}
3142
3143/**
3144 * sys_rt_sigpending - examine a pending signal that has been raised
3145 * while blocked
3146 * @uset: stores pending signals
3147 * @sigsetsize: size of sigset_t type or larger
3148 */
3149SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3150{
3151 sigset_t set;
3152
3153 if (sigsetsize > sizeof(*uset))
3154 return -EINVAL;
3155
3156 do_sigpending(&set);
3157
3158 if (copy_to_user(uset, &set, sigsetsize))
3159 return -EFAULT;
3160
3161 return 0;
3162}
3163
3164#ifdef CONFIG_COMPAT
3165COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3166 compat_size_t, sigsetsize)
3167{
3168 sigset_t set;
3169
3170 if (sigsetsize > sizeof(*uset))
3171 return -EINVAL;
3172
3173 do_sigpending(&set);
3174
3175 return put_compat_sigset(uset, &set, sigsetsize);
3176}
3177#endif
3178
3179static const struct {
3180 unsigned char limit, layout;
3181} sig_sicodes[] = {
3182 [SIGILL] = { NSIGILL, SIL_FAULT },
3183 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3184 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3185 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3186 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3187#if defined(SIGEMT)
3188 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3189#endif
3190 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3191 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3192 [SIGSYS] = { NSIGSYS, SIL_SYS },
3193};
3194
3195static bool known_siginfo_layout(unsigned sig, int si_code)
3196{
3197 if (si_code == SI_KERNEL)
3198 return true;
3199 else if ((si_code > SI_USER)) {
3200 if (sig_specific_sicodes(sig)) {
3201 if (si_code <= sig_sicodes[sig].limit)
3202 return true;
3203 }
3204 else if (si_code <= NSIGPOLL)
3205 return true;
3206 }
3207 else if (si_code >= SI_DETHREAD)
3208 return true;
3209 else if (si_code == SI_ASYNCNL)
3210 return true;
3211 return false;
3212}
3213
3214enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3215{
3216 enum siginfo_layout layout = SIL_KILL;
3217 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3218 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3219 (si_code <= sig_sicodes[sig].limit)) {
3220 layout = sig_sicodes[sig].layout;
3221 /* Handle the exceptions */
3222 if ((sig == SIGBUS) &&
3223 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3224 layout = SIL_FAULT_MCEERR;
3225 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3226 layout = SIL_FAULT_BNDERR;
3227#ifdef SEGV_PKUERR
3228 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3229 layout = SIL_FAULT_PKUERR;
3230#endif
3231 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3232 layout = SIL_PERF_EVENT;
3233#ifdef __ARCH_SI_TRAPNO
3234 else if (layout == SIL_FAULT)
3235 layout = SIL_FAULT_TRAPNO;
3236#endif
3237 }
3238 else if (si_code <= NSIGPOLL)
3239 layout = SIL_POLL;
3240 } else {
3241 if (si_code == SI_TIMER)
3242 layout = SIL_TIMER;
3243 else if (si_code == SI_SIGIO)
3244 layout = SIL_POLL;
3245 else if (si_code < 0)
3246 layout = SIL_RT;
3247 }
3248 return layout;
3249}
3250
3251static inline char __user *si_expansion(const siginfo_t __user *info)
3252{
3253 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3254}
3255
3256int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3257{
3258 char __user *expansion = si_expansion(to);
3259 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3260 return -EFAULT;
3261 if (clear_user(expansion, SI_EXPANSION_SIZE))
3262 return -EFAULT;
3263 return 0;
3264}
3265
3266static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3267 const siginfo_t __user *from)
3268{
3269 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3270 char __user *expansion = si_expansion(from);
3271 char buf[SI_EXPANSION_SIZE];
3272 int i;
3273 /*
3274 * An unknown si_code might need more than
3275 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3276 * extra bytes are 0. This guarantees copy_siginfo_to_user
3277 * will return this data to userspace exactly.
3278 */
3279 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3280 return -EFAULT;
3281 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3282 if (buf[i] != 0)
3283 return -E2BIG;
3284 }
3285 }
3286 return 0;
3287}
3288
3289static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3290 const siginfo_t __user *from)
3291{
3292 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3293 return -EFAULT;
3294 to->si_signo = signo;
3295 return post_copy_siginfo_from_user(to, from);
3296}
3297
3298int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3299{
3300 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3301 return -EFAULT;
3302 return post_copy_siginfo_from_user(to, from);
3303}
3304
3305#ifdef CONFIG_COMPAT
3306/**
3307 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3308 * @to: compat siginfo destination
3309 * @from: kernel siginfo source
3310 *
3311 * Note: This function does not work properly for the SIGCHLD on x32, but
3312 * fortunately it doesn't have to. The only valid callers for this function are
3313 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3314 * The latter does not care because SIGCHLD will never cause a coredump.
3315 */
3316void copy_siginfo_to_external32(struct compat_siginfo *to,
3317 const struct kernel_siginfo *from)
3318{
3319 memset(to, 0, sizeof(*to));
3320
3321 to->si_signo = from->si_signo;
3322 to->si_errno = from->si_errno;
3323 to->si_code = from->si_code;
3324 switch(siginfo_layout(from->si_signo, from->si_code)) {
3325 case SIL_KILL:
3326 to->si_pid = from->si_pid;
3327 to->si_uid = from->si_uid;
3328 break;
3329 case SIL_TIMER:
3330 to->si_tid = from->si_tid;
3331 to->si_overrun = from->si_overrun;
3332 to->si_int = from->si_int;
3333 break;
3334 case SIL_POLL:
3335 to->si_band = from->si_band;
3336 to->si_fd = from->si_fd;
3337 break;
3338 case SIL_FAULT:
3339 to->si_addr = ptr_to_compat(from->si_addr);
3340 break;
3341 case SIL_FAULT_TRAPNO:
3342 to->si_addr = ptr_to_compat(from->si_addr);
3343 to->si_trapno = from->si_trapno;
3344 break;
3345 case SIL_FAULT_MCEERR:
3346 to->si_addr = ptr_to_compat(from->si_addr);
3347 to->si_addr_lsb = from->si_addr_lsb;
3348 break;
3349 case SIL_FAULT_BNDERR:
3350 to->si_addr = ptr_to_compat(from->si_addr);
3351 to->si_lower = ptr_to_compat(from->si_lower);
3352 to->si_upper = ptr_to_compat(from->si_upper);
3353 break;
3354 case SIL_FAULT_PKUERR:
3355 to->si_addr = ptr_to_compat(from->si_addr);
3356 to->si_pkey = from->si_pkey;
3357 break;
3358 case SIL_PERF_EVENT:
3359 to->si_addr = ptr_to_compat(from->si_addr);
3360 to->si_perf_data = from->si_perf_data;
3361 to->si_perf_type = from->si_perf_type;
3362 break;
3363 case SIL_CHLD:
3364 to->si_pid = from->si_pid;
3365 to->si_uid = from->si_uid;
3366 to->si_status = from->si_status;
3367 to->si_utime = from->si_utime;
3368 to->si_stime = from->si_stime;
3369 break;
3370 case SIL_RT:
3371 to->si_pid = from->si_pid;
3372 to->si_uid = from->si_uid;
3373 to->si_int = from->si_int;
3374 break;
3375 case SIL_SYS:
3376 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3377 to->si_syscall = from->si_syscall;
3378 to->si_arch = from->si_arch;
3379 break;
3380 }
3381}
3382
3383int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3384 const struct kernel_siginfo *from)
3385{
3386 struct compat_siginfo new;
3387
3388 copy_siginfo_to_external32(&new, from);
3389 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3390 return -EFAULT;
3391 return 0;
3392}
3393
3394static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3395 const struct compat_siginfo *from)
3396{
3397 clear_siginfo(to);
3398 to->si_signo = from->si_signo;
3399 to->si_errno = from->si_errno;
3400 to->si_code = from->si_code;
3401 switch(siginfo_layout(from->si_signo, from->si_code)) {
3402 case SIL_KILL:
3403 to->si_pid = from->si_pid;
3404 to->si_uid = from->si_uid;
3405 break;
3406 case SIL_TIMER:
3407 to->si_tid = from->si_tid;
3408 to->si_overrun = from->si_overrun;
3409 to->si_int = from->si_int;
3410 break;
3411 case SIL_POLL:
3412 to->si_band = from->si_band;
3413 to->si_fd = from->si_fd;
3414 break;
3415 case SIL_FAULT:
3416 to->si_addr = compat_ptr(from->si_addr);
3417 break;
3418 case SIL_FAULT_TRAPNO:
3419 to->si_addr = compat_ptr(from->si_addr);
3420 to->si_trapno = from->si_trapno;
3421 break;
3422 case SIL_FAULT_MCEERR:
3423 to->si_addr = compat_ptr(from->si_addr);
3424 to->si_addr_lsb = from->si_addr_lsb;
3425 break;
3426 case SIL_FAULT_BNDERR:
3427 to->si_addr = compat_ptr(from->si_addr);
3428 to->si_lower = compat_ptr(from->si_lower);
3429 to->si_upper = compat_ptr(from->si_upper);
3430 break;
3431 case SIL_FAULT_PKUERR:
3432 to->si_addr = compat_ptr(from->si_addr);
3433 to->si_pkey = from->si_pkey;
3434 break;
3435 case SIL_PERF_EVENT:
3436 to->si_addr = compat_ptr(from->si_addr);
3437 to->si_perf_data = from->si_perf_data;
3438 to->si_perf_type = from->si_perf_type;
3439 break;
3440 case SIL_CHLD:
3441 to->si_pid = from->si_pid;
3442 to->si_uid = from->si_uid;
3443 to->si_status = from->si_status;
3444#ifdef CONFIG_X86_X32_ABI
3445 if (in_x32_syscall()) {
3446 to->si_utime = from->_sifields._sigchld_x32._utime;
3447 to->si_stime = from->_sifields._sigchld_x32._stime;
3448 } else
3449#endif
3450 {
3451 to->si_utime = from->si_utime;
3452 to->si_stime = from->si_stime;
3453 }
3454 break;
3455 case SIL_RT:
3456 to->si_pid = from->si_pid;
3457 to->si_uid = from->si_uid;
3458 to->si_int = from->si_int;
3459 break;
3460 case SIL_SYS:
3461 to->si_call_addr = compat_ptr(from->si_call_addr);
3462 to->si_syscall = from->si_syscall;
3463 to->si_arch = from->si_arch;
3464 break;
3465 }
3466 return 0;
3467}
3468
3469static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3470 const struct compat_siginfo __user *ufrom)
3471{
3472 struct compat_siginfo from;
3473
3474 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3475 return -EFAULT;
3476
3477 from.si_signo = signo;
3478 return post_copy_siginfo_from_user32(to, &from);
3479}
3480
3481int copy_siginfo_from_user32(struct kernel_siginfo *to,
3482 const struct compat_siginfo __user *ufrom)
3483{
3484 struct compat_siginfo from;
3485
3486 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3487 return -EFAULT;
3488
3489 return post_copy_siginfo_from_user32(to, &from);
3490}
3491#endif /* CONFIG_COMPAT */
3492
3493/**
3494 * do_sigtimedwait - wait for queued signals specified in @which
3495 * @which: queued signals to wait for
3496 * @info: if non-null, the signal's siginfo is returned here
3497 * @ts: upper bound on process time suspension
3498 */
3499static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3500 const struct timespec64 *ts)
3501{
3502 ktime_t *to = NULL, timeout = KTIME_MAX;
3503 struct task_struct *tsk = current;
3504 sigset_t mask = *which;
3505 int sig, ret = 0;
3506
3507 if (ts) {
3508 if (!timespec64_valid(ts))
3509 return -EINVAL;
3510 timeout = timespec64_to_ktime(*ts);
3511 to = &timeout;
3512 }
3513
3514 /*
3515 * Invert the set of allowed signals to get those we want to block.
3516 */
3517 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3518 signotset(&mask);
3519
3520 spin_lock_irq(&tsk->sighand->siglock);
3521 sig = dequeue_signal(tsk, &mask, info);
3522 if (!sig && timeout) {
3523 /*
3524 * None ready, temporarily unblock those we're interested
3525 * while we are sleeping in so that we'll be awakened when
3526 * they arrive. Unblocking is always fine, we can avoid
3527 * set_current_blocked().
3528 */
3529 tsk->real_blocked = tsk->blocked;
3530 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3531 recalc_sigpending();
3532 spin_unlock_irq(&tsk->sighand->siglock);
3533
3534 __set_current_state(TASK_INTERRUPTIBLE);
3535 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3536 HRTIMER_MODE_REL);
3537 spin_lock_irq(&tsk->sighand->siglock);
3538 __set_task_blocked(tsk, &tsk->real_blocked);
3539 sigemptyset(&tsk->real_blocked);
3540 sig = dequeue_signal(tsk, &mask, info);
3541 }
3542 spin_unlock_irq(&tsk->sighand->siglock);
3543
3544 if (sig)
3545 return sig;
3546 return ret ? -EINTR : -EAGAIN;
3547}
3548
3549/**
3550 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3551 * in @uthese
3552 * @uthese: queued signals to wait for
3553 * @uinfo: if non-null, the signal's siginfo is returned here
3554 * @uts: upper bound on process time suspension
3555 * @sigsetsize: size of sigset_t type
3556 */
3557SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3558 siginfo_t __user *, uinfo,
3559 const struct __kernel_timespec __user *, uts,
3560 size_t, sigsetsize)
3561{
3562 sigset_t these;
3563 struct timespec64 ts;
3564 kernel_siginfo_t info;
3565 int ret;
3566
3567 /* XXX: Don't preclude handling different sized sigset_t's. */
3568 if (sigsetsize != sizeof(sigset_t))
3569 return -EINVAL;
3570
3571 if (copy_from_user(&these, uthese, sizeof(these)))
3572 return -EFAULT;
3573
3574 if (uts) {
3575 if (get_timespec64(&ts, uts))
3576 return -EFAULT;
3577 }
3578
3579 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3580
3581 if (ret > 0 && uinfo) {
3582 if (copy_siginfo_to_user(uinfo, &info))
3583 ret = -EFAULT;
3584 }
3585
3586 return ret;
3587}
3588
3589#ifdef CONFIG_COMPAT_32BIT_TIME
3590SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3591 siginfo_t __user *, uinfo,
3592 const struct old_timespec32 __user *, uts,
3593 size_t, sigsetsize)
3594{
3595 sigset_t these;
3596 struct timespec64 ts;
3597 kernel_siginfo_t info;
3598 int ret;
3599
3600 if (sigsetsize != sizeof(sigset_t))
3601 return -EINVAL;
3602
3603 if (copy_from_user(&these, uthese, sizeof(these)))
3604 return -EFAULT;
3605
3606 if (uts) {
3607 if (get_old_timespec32(&ts, uts))
3608 return -EFAULT;
3609 }
3610
3611 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3612
3613 if (ret > 0 && uinfo) {
3614 if (copy_siginfo_to_user(uinfo, &info))
3615 ret = -EFAULT;
3616 }
3617
3618 return ret;
3619}
3620#endif
3621
3622#ifdef CONFIG_COMPAT
3623COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3624 struct compat_siginfo __user *, uinfo,
3625 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3626{
3627 sigset_t s;
3628 struct timespec64 t;
3629 kernel_siginfo_t info;
3630 long ret;
3631
3632 if (sigsetsize != sizeof(sigset_t))
3633 return -EINVAL;
3634
3635 if (get_compat_sigset(&s, uthese))
3636 return -EFAULT;
3637
3638 if (uts) {
3639 if (get_timespec64(&t, uts))
3640 return -EFAULT;
3641 }
3642
3643 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3644
3645 if (ret > 0 && uinfo) {
3646 if (copy_siginfo_to_user32(uinfo, &info))
3647 ret = -EFAULT;
3648 }
3649
3650 return ret;
3651}
3652
3653#ifdef CONFIG_COMPAT_32BIT_TIME
3654COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3655 struct compat_siginfo __user *, uinfo,
3656 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3657{
3658 sigset_t s;
3659 struct timespec64 t;
3660 kernel_siginfo_t info;
3661 long ret;
3662
3663 if (sigsetsize != sizeof(sigset_t))
3664 return -EINVAL;
3665
3666 if (get_compat_sigset(&s, uthese))
3667 return -EFAULT;
3668
3669 if (uts) {
3670 if (get_old_timespec32(&t, uts))
3671 return -EFAULT;
3672 }
3673
3674 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3675
3676 if (ret > 0 && uinfo) {
3677 if (copy_siginfo_to_user32(uinfo, &info))
3678 ret = -EFAULT;
3679 }
3680
3681 return ret;
3682}
3683#endif
3684#endif
3685
3686static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3687{
3688 clear_siginfo(info);
3689 info->si_signo = sig;
3690 info->si_errno = 0;
3691 info->si_code = SI_USER;
3692 info->si_pid = task_tgid_vnr(current);
3693 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3694}
3695
3696/**
3697 * sys_kill - send a signal to a process
3698 * @pid: the PID of the process
3699 * @sig: signal to be sent
3700 */
3701SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3702{
3703 struct kernel_siginfo info;
3704
3705 prepare_kill_siginfo(sig, &info);
3706
3707 return kill_something_info(sig, &info, pid);
3708}
3709
3710/*
3711 * Verify that the signaler and signalee either are in the same pid namespace
3712 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3713 * namespace.
3714 */
3715static bool access_pidfd_pidns(struct pid *pid)
3716{
3717 struct pid_namespace *active = task_active_pid_ns(current);
3718 struct pid_namespace *p = ns_of_pid(pid);
3719
3720 for (;;) {
3721 if (!p)
3722 return false;
3723 if (p == active)
3724 break;
3725 p = p->parent;
3726 }
3727
3728 return true;
3729}
3730
3731static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3732 siginfo_t __user *info)
3733{
3734#ifdef CONFIG_COMPAT
3735 /*
3736 * Avoid hooking up compat syscalls and instead handle necessary
3737 * conversions here. Note, this is a stop-gap measure and should not be
3738 * considered a generic solution.
3739 */
3740 if (in_compat_syscall())
3741 return copy_siginfo_from_user32(
3742 kinfo, (struct compat_siginfo __user *)info);
3743#endif
3744 return copy_siginfo_from_user(kinfo, info);
3745}
3746
3747static struct pid *pidfd_to_pid(const struct file *file)
3748{
3749 struct pid *pid;
3750
3751 pid = pidfd_pid(file);
3752 if (!IS_ERR(pid))
3753 return pid;
3754
3755 return tgid_pidfd_to_pid(file);
3756}
3757
3758/**
3759 * sys_pidfd_send_signal - Signal a process through a pidfd
3760 * @pidfd: file descriptor of the process
3761 * @sig: signal to send
3762 * @info: signal info
3763 * @flags: future flags
3764 *
3765 * The syscall currently only signals via PIDTYPE_PID which covers
3766 * kill(<positive-pid>, <signal>. It does not signal threads or process
3767 * groups.
3768 * In order to extend the syscall to threads and process groups the @flags
3769 * argument should be used. In essence, the @flags argument will determine
3770 * what is signaled and not the file descriptor itself. Put in other words,
3771 * grouping is a property of the flags argument not a property of the file
3772 * descriptor.
3773 *
3774 * Return: 0 on success, negative errno on failure
3775 */
3776SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3777 siginfo_t __user *, info, unsigned int, flags)
3778{
3779 int ret;
3780 struct fd f;
3781 struct pid *pid;
3782 kernel_siginfo_t kinfo;
3783
3784 /* Enforce flags be set to 0 until we add an extension. */
3785 if (flags)
3786 return -EINVAL;
3787
3788 f = fdget(pidfd);
3789 if (!f.file)
3790 return -EBADF;
3791
3792 /* Is this a pidfd? */
3793 pid = pidfd_to_pid(f.file);
3794 if (IS_ERR(pid)) {
3795 ret = PTR_ERR(pid);
3796 goto err;
3797 }
3798
3799 ret = -EINVAL;
3800 if (!access_pidfd_pidns(pid))
3801 goto err;
3802
3803 if (info) {
3804 ret = copy_siginfo_from_user_any(&kinfo, info);
3805 if (unlikely(ret))
3806 goto err;
3807
3808 ret = -EINVAL;
3809 if (unlikely(sig != kinfo.si_signo))
3810 goto err;
3811
3812 /* Only allow sending arbitrary signals to yourself. */
3813 ret = -EPERM;
3814 if ((task_pid(current) != pid) &&
3815 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3816 goto err;
3817 } else {
3818 prepare_kill_siginfo(sig, &kinfo);
3819 }
3820
3821 ret = kill_pid_info(sig, &kinfo, pid);
3822
3823err:
3824 fdput(f);
3825 return ret;
3826}
3827
3828static int
3829do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3830{
3831 struct task_struct *p;
3832 int error = -ESRCH;
3833
3834 rcu_read_lock();
3835 p = find_task_by_vpid(pid);
3836 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3837 error = check_kill_permission(sig, info, p);
3838 /*
3839 * The null signal is a permissions and process existence
3840 * probe. No signal is actually delivered.
3841 */
3842 if (!error && sig) {
3843 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3844 /*
3845 * If lock_task_sighand() failed we pretend the task
3846 * dies after receiving the signal. The window is tiny,
3847 * and the signal is private anyway.
3848 */
3849 if (unlikely(error == -ESRCH))
3850 error = 0;
3851 }
3852 }
3853 rcu_read_unlock();
3854
3855 return error;
3856}
3857
3858static int do_tkill(pid_t tgid, pid_t pid, int sig)
3859{
3860 struct kernel_siginfo info;
3861
3862 clear_siginfo(&info);
3863 info.si_signo = sig;
3864 info.si_errno = 0;
3865 info.si_code = SI_TKILL;
3866 info.si_pid = task_tgid_vnr(current);
3867 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3868
3869 return do_send_specific(tgid, pid, sig, &info);
3870}
3871
3872/**
3873 * sys_tgkill - send signal to one specific thread
3874 * @tgid: the thread group ID of the thread
3875 * @pid: the PID of the thread
3876 * @sig: signal to be sent
3877 *
3878 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3879 * exists but it's not belonging to the target process anymore. This
3880 * method solves the problem of threads exiting and PIDs getting reused.
3881 */
3882SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3883{
3884 /* This is only valid for single tasks */
3885 if (pid <= 0 || tgid <= 0)
3886 return -EINVAL;
3887
3888 return do_tkill(tgid, pid, sig);
3889}
3890
3891/**
3892 * sys_tkill - send signal to one specific task
3893 * @pid: the PID of the task
3894 * @sig: signal to be sent
3895 *
3896 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3897 */
3898SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3899{
3900 /* This is only valid for single tasks */
3901 if (pid <= 0)
3902 return -EINVAL;
3903
3904 return do_tkill(0, pid, sig);
3905}
3906
3907static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3908{
3909 /* Not even root can pretend to send signals from the kernel.
3910 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3911 */
3912 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3913 (task_pid_vnr(current) != pid))
3914 return -EPERM;
3915
3916 /* POSIX.1b doesn't mention process groups. */
3917 return kill_proc_info(sig, info, pid);
3918}
3919
3920/**
3921 * sys_rt_sigqueueinfo - send signal information to a signal
3922 * @pid: the PID of the thread
3923 * @sig: signal to be sent
3924 * @uinfo: signal info to be sent
3925 */
3926SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3927 siginfo_t __user *, uinfo)
3928{
3929 kernel_siginfo_t info;
3930 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3931 if (unlikely(ret))
3932 return ret;
3933 return do_rt_sigqueueinfo(pid, sig, &info);
3934}
3935
3936#ifdef CONFIG_COMPAT
3937COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3938 compat_pid_t, pid,
3939 int, sig,
3940 struct compat_siginfo __user *, uinfo)
3941{
3942 kernel_siginfo_t info;
3943 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3944 if (unlikely(ret))
3945 return ret;
3946 return do_rt_sigqueueinfo(pid, sig, &info);
3947}
3948#endif
3949
3950static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
3951{
3952 /* This is only valid for single tasks */
3953 if (pid <= 0 || tgid <= 0)
3954 return -EINVAL;
3955
3956 /* Not even root can pretend to send signals from the kernel.
3957 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3958 */
3959 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3960 (task_pid_vnr(current) != pid))
3961 return -EPERM;
3962
3963 return do_send_specific(tgid, pid, sig, info);
3964}
3965
3966SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3967 siginfo_t __user *, uinfo)
3968{
3969 kernel_siginfo_t info;
3970 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3971 if (unlikely(ret))
3972 return ret;
3973 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3974}
3975
3976#ifdef CONFIG_COMPAT
3977COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3978 compat_pid_t, tgid,
3979 compat_pid_t, pid,
3980 int, sig,
3981 struct compat_siginfo __user *, uinfo)
3982{
3983 kernel_siginfo_t info;
3984 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3985 if (unlikely(ret))
3986 return ret;
3987 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3988}
3989#endif
3990
3991/*
3992 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3993 */
3994void kernel_sigaction(int sig, __sighandler_t action)
3995{
3996 spin_lock_irq(¤t->sighand->siglock);
3997 current->sighand->action[sig - 1].sa.sa_handler = action;
3998 if (action == SIG_IGN) {
3999 sigset_t mask;
4000
4001 sigemptyset(&mask);
4002 sigaddset(&mask, sig);
4003
4004 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4005 flush_sigqueue_mask(&mask, ¤t->pending);
4006 recalc_sigpending();
4007 }
4008 spin_unlock_irq(¤t->sighand->siglock);
4009}
4010EXPORT_SYMBOL(kernel_sigaction);
4011
4012void __weak sigaction_compat_abi(struct k_sigaction *act,
4013 struct k_sigaction *oact)
4014{
4015}
4016
4017int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4018{
4019 struct task_struct *p = current, *t;
4020 struct k_sigaction *k;
4021 sigset_t mask;
4022
4023 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4024 return -EINVAL;
4025
4026 k = &p->sighand->action[sig-1];
4027
4028 spin_lock_irq(&p->sighand->siglock);
4029 if (oact)
4030 *oact = *k;
4031
4032 /*
4033 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4034 * e.g. by having an architecture use the bit in their uapi.
4035 */
4036 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4037
4038 /*
4039 * Clear unknown flag bits in order to allow userspace to detect missing
4040 * support for flag bits and to allow the kernel to use non-uapi bits
4041 * internally.
4042 */
4043 if (act)
4044 act->sa.sa_flags &= UAPI_SA_FLAGS;
4045 if (oact)
4046 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4047
4048 sigaction_compat_abi(act, oact);
4049
4050 if (act) {
4051 sigdelsetmask(&act->sa.sa_mask,
4052 sigmask(SIGKILL) | sigmask(SIGSTOP));
4053 *k = *act;
4054 /*
4055 * POSIX 3.3.1.3:
4056 * "Setting a signal action to SIG_IGN for a signal that is
4057 * pending shall cause the pending signal to be discarded,
4058 * whether or not it is blocked."
4059 *
4060 * "Setting a signal action to SIG_DFL for a signal that is
4061 * pending and whose default action is to ignore the signal
4062 * (for example, SIGCHLD), shall cause the pending signal to
4063 * be discarded, whether or not it is blocked"
4064 */
4065 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4066 sigemptyset(&mask);
4067 sigaddset(&mask, sig);
4068 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4069 for_each_thread(p, t)
4070 flush_sigqueue_mask(&mask, &t->pending);
4071 }
4072 }
4073
4074 spin_unlock_irq(&p->sighand->siglock);
4075 return 0;
4076}
4077
4078static int
4079do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4080 size_t min_ss_size)
4081{
4082 struct task_struct *t = current;
4083
4084 if (oss) {
4085 memset(oss, 0, sizeof(stack_t));
4086 oss->ss_sp = (void __user *) t->sas_ss_sp;
4087 oss->ss_size = t->sas_ss_size;
4088 oss->ss_flags = sas_ss_flags(sp) |
4089 (current->sas_ss_flags & SS_FLAG_BITS);
4090 }
4091
4092 if (ss) {
4093 void __user *ss_sp = ss->ss_sp;
4094 size_t ss_size = ss->ss_size;
4095 unsigned ss_flags = ss->ss_flags;
4096 int ss_mode;
4097
4098 if (unlikely(on_sig_stack(sp)))
4099 return -EPERM;
4100
4101 ss_mode = ss_flags & ~SS_FLAG_BITS;
4102 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4103 ss_mode != 0))
4104 return -EINVAL;
4105
4106 if (ss_mode == SS_DISABLE) {
4107 ss_size = 0;
4108 ss_sp = NULL;
4109 } else {
4110 if (unlikely(ss_size < min_ss_size))
4111 return -ENOMEM;
4112 }
4113
4114 t->sas_ss_sp = (unsigned long) ss_sp;
4115 t->sas_ss_size = ss_size;
4116 t->sas_ss_flags = ss_flags;
4117 }
4118 return 0;
4119}
4120
4121SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4122{
4123 stack_t new, old;
4124 int err;
4125 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4126 return -EFAULT;
4127 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4128 current_user_stack_pointer(),
4129 MINSIGSTKSZ);
4130 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4131 err = -EFAULT;
4132 return err;
4133}
4134
4135int restore_altstack(const stack_t __user *uss)
4136{
4137 stack_t new;
4138 if (copy_from_user(&new, uss, sizeof(stack_t)))
4139 return -EFAULT;
4140 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4141 MINSIGSTKSZ);
4142 /* squash all but EFAULT for now */
4143 return 0;
4144}
4145
4146int __save_altstack(stack_t __user *uss, unsigned long sp)
4147{
4148 struct task_struct *t = current;
4149 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4150 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4151 __put_user(t->sas_ss_size, &uss->ss_size);
4152 return err;
4153}
4154
4155#ifdef CONFIG_COMPAT
4156static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4157 compat_stack_t __user *uoss_ptr)
4158{
4159 stack_t uss, uoss;
4160 int ret;
4161
4162 if (uss_ptr) {
4163 compat_stack_t uss32;
4164 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4165 return -EFAULT;
4166 uss.ss_sp = compat_ptr(uss32.ss_sp);
4167 uss.ss_flags = uss32.ss_flags;
4168 uss.ss_size = uss32.ss_size;
4169 }
4170 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4171 compat_user_stack_pointer(),
4172 COMPAT_MINSIGSTKSZ);
4173 if (ret >= 0 && uoss_ptr) {
4174 compat_stack_t old;
4175 memset(&old, 0, sizeof(old));
4176 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4177 old.ss_flags = uoss.ss_flags;
4178 old.ss_size = uoss.ss_size;
4179 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4180 ret = -EFAULT;
4181 }
4182 return ret;
4183}
4184
4185COMPAT_SYSCALL_DEFINE2(sigaltstack,
4186 const compat_stack_t __user *, uss_ptr,
4187 compat_stack_t __user *, uoss_ptr)
4188{
4189 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4190}
4191
4192int compat_restore_altstack(const compat_stack_t __user *uss)
4193{
4194 int err = do_compat_sigaltstack(uss, NULL);
4195 /* squash all but -EFAULT for now */
4196 return err == -EFAULT ? err : 0;
4197}
4198
4199int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4200{
4201 int err;
4202 struct task_struct *t = current;
4203 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4204 &uss->ss_sp) |
4205 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4206 __put_user(t->sas_ss_size, &uss->ss_size);
4207 return err;
4208}
4209#endif
4210
4211#ifdef __ARCH_WANT_SYS_SIGPENDING
4212
4213/**
4214 * sys_sigpending - examine pending signals
4215 * @uset: where mask of pending signal is returned
4216 */
4217SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4218{
4219 sigset_t set;
4220
4221 if (sizeof(old_sigset_t) > sizeof(*uset))
4222 return -EINVAL;
4223
4224 do_sigpending(&set);
4225
4226 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4227 return -EFAULT;
4228
4229 return 0;
4230}
4231
4232#ifdef CONFIG_COMPAT
4233COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4234{
4235 sigset_t set;
4236
4237 do_sigpending(&set);
4238
4239 return put_user(set.sig[0], set32);
4240}
4241#endif
4242
4243#endif
4244
4245#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4246/**
4247 * sys_sigprocmask - examine and change blocked signals
4248 * @how: whether to add, remove, or set signals
4249 * @nset: signals to add or remove (if non-null)
4250 * @oset: previous value of signal mask if non-null
4251 *
4252 * Some platforms have their own version with special arguments;
4253 * others support only sys_rt_sigprocmask.
4254 */
4255
4256SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4257 old_sigset_t __user *, oset)
4258{
4259 old_sigset_t old_set, new_set;
4260 sigset_t new_blocked;
4261
4262 old_set = current->blocked.sig[0];
4263
4264 if (nset) {
4265 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4266 return -EFAULT;
4267
4268 new_blocked = current->blocked;
4269
4270 switch (how) {
4271 case SIG_BLOCK:
4272 sigaddsetmask(&new_blocked, new_set);
4273 break;
4274 case SIG_UNBLOCK:
4275 sigdelsetmask(&new_blocked, new_set);
4276 break;
4277 case SIG_SETMASK:
4278 new_blocked.sig[0] = new_set;
4279 break;
4280 default:
4281 return -EINVAL;
4282 }
4283
4284 set_current_blocked(&new_blocked);
4285 }
4286
4287 if (oset) {
4288 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4289 return -EFAULT;
4290 }
4291
4292 return 0;
4293}
4294#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4295
4296#ifndef CONFIG_ODD_RT_SIGACTION
4297/**
4298 * sys_rt_sigaction - alter an action taken by a process
4299 * @sig: signal to be sent
4300 * @act: new sigaction
4301 * @oact: used to save the previous sigaction
4302 * @sigsetsize: size of sigset_t type
4303 */
4304SYSCALL_DEFINE4(rt_sigaction, int, sig,
4305 const struct sigaction __user *, act,
4306 struct sigaction __user *, oact,
4307 size_t, sigsetsize)
4308{
4309 struct k_sigaction new_sa, old_sa;
4310 int ret;
4311
4312 /* XXX: Don't preclude handling different sized sigset_t's. */
4313 if (sigsetsize != sizeof(sigset_t))
4314 return -EINVAL;
4315
4316 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4317 return -EFAULT;
4318
4319 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4320 if (ret)
4321 return ret;
4322
4323 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4324 return -EFAULT;
4325
4326 return 0;
4327}
4328#ifdef CONFIG_COMPAT
4329COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4330 const struct compat_sigaction __user *, act,
4331 struct compat_sigaction __user *, oact,
4332 compat_size_t, sigsetsize)
4333{
4334 struct k_sigaction new_ka, old_ka;
4335#ifdef __ARCH_HAS_SA_RESTORER
4336 compat_uptr_t restorer;
4337#endif
4338 int ret;
4339
4340 /* XXX: Don't preclude handling different sized sigset_t's. */
4341 if (sigsetsize != sizeof(compat_sigset_t))
4342 return -EINVAL;
4343
4344 if (act) {
4345 compat_uptr_t handler;
4346 ret = get_user(handler, &act->sa_handler);
4347 new_ka.sa.sa_handler = compat_ptr(handler);
4348#ifdef __ARCH_HAS_SA_RESTORER
4349 ret |= get_user(restorer, &act->sa_restorer);
4350 new_ka.sa.sa_restorer = compat_ptr(restorer);
4351#endif
4352 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4353 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4354 if (ret)
4355 return -EFAULT;
4356 }
4357
4358 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4359 if (!ret && oact) {
4360 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4361 &oact->sa_handler);
4362 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4363 sizeof(oact->sa_mask));
4364 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4365#ifdef __ARCH_HAS_SA_RESTORER
4366 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4367 &oact->sa_restorer);
4368#endif
4369 }
4370 return ret;
4371}
4372#endif
4373#endif /* !CONFIG_ODD_RT_SIGACTION */
4374
4375#ifdef CONFIG_OLD_SIGACTION
4376SYSCALL_DEFINE3(sigaction, int, sig,
4377 const struct old_sigaction __user *, act,
4378 struct old_sigaction __user *, oact)
4379{
4380 struct k_sigaction new_ka, old_ka;
4381 int ret;
4382
4383 if (act) {
4384 old_sigset_t mask;
4385 if (!access_ok(act, sizeof(*act)) ||
4386 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4387 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4388 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4389 __get_user(mask, &act->sa_mask))
4390 return -EFAULT;
4391#ifdef __ARCH_HAS_KA_RESTORER
4392 new_ka.ka_restorer = NULL;
4393#endif
4394 siginitset(&new_ka.sa.sa_mask, mask);
4395 }
4396
4397 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4398
4399 if (!ret && oact) {
4400 if (!access_ok(oact, sizeof(*oact)) ||
4401 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4402 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4403 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4404 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4405 return -EFAULT;
4406 }
4407
4408 return ret;
4409}
4410#endif
4411#ifdef CONFIG_COMPAT_OLD_SIGACTION
4412COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4413 const struct compat_old_sigaction __user *, act,
4414 struct compat_old_sigaction __user *, oact)
4415{
4416 struct k_sigaction new_ka, old_ka;
4417 int ret;
4418 compat_old_sigset_t mask;
4419 compat_uptr_t handler, restorer;
4420
4421 if (act) {
4422 if (!access_ok(act, sizeof(*act)) ||
4423 __get_user(handler, &act->sa_handler) ||
4424 __get_user(restorer, &act->sa_restorer) ||
4425 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4426 __get_user(mask, &act->sa_mask))
4427 return -EFAULT;
4428
4429#ifdef __ARCH_HAS_KA_RESTORER
4430 new_ka.ka_restorer = NULL;
4431#endif
4432 new_ka.sa.sa_handler = compat_ptr(handler);
4433 new_ka.sa.sa_restorer = compat_ptr(restorer);
4434 siginitset(&new_ka.sa.sa_mask, mask);
4435 }
4436
4437 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4438
4439 if (!ret && oact) {
4440 if (!access_ok(oact, sizeof(*oact)) ||
4441 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4442 &oact->sa_handler) ||
4443 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4444 &oact->sa_restorer) ||
4445 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4446 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4447 return -EFAULT;
4448 }
4449 return ret;
4450}
4451#endif
4452
4453#ifdef CONFIG_SGETMASK_SYSCALL
4454
4455/*
4456 * For backwards compatibility. Functionality superseded by sigprocmask.
4457 */
4458SYSCALL_DEFINE0(sgetmask)
4459{
4460 /* SMP safe */
4461 return current->blocked.sig[0];
4462}
4463
4464SYSCALL_DEFINE1(ssetmask, int, newmask)
4465{
4466 int old = current->blocked.sig[0];
4467 sigset_t newset;
4468
4469 siginitset(&newset, newmask);
4470 set_current_blocked(&newset);
4471
4472 return old;
4473}
4474#endif /* CONFIG_SGETMASK_SYSCALL */
4475
4476#ifdef __ARCH_WANT_SYS_SIGNAL
4477/*
4478 * For backwards compatibility. Functionality superseded by sigaction.
4479 */
4480SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4481{
4482 struct k_sigaction new_sa, old_sa;
4483 int ret;
4484
4485 new_sa.sa.sa_handler = handler;
4486 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4487 sigemptyset(&new_sa.sa.sa_mask);
4488
4489 ret = do_sigaction(sig, &new_sa, &old_sa);
4490
4491 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4492}
4493#endif /* __ARCH_WANT_SYS_SIGNAL */
4494
4495#ifdef __ARCH_WANT_SYS_PAUSE
4496
4497SYSCALL_DEFINE0(pause)
4498{
4499 while (!signal_pending(current)) {
4500 __set_current_state(TASK_INTERRUPTIBLE);
4501 schedule();
4502 }
4503 return -ERESTARTNOHAND;
4504}
4505
4506#endif
4507
4508static int sigsuspend(sigset_t *set)
4509{
4510 current->saved_sigmask = current->blocked;
4511 set_current_blocked(set);
4512
4513 while (!signal_pending(current)) {
4514 __set_current_state(TASK_INTERRUPTIBLE);
4515 schedule();
4516 }
4517 set_restore_sigmask();
4518 return -ERESTARTNOHAND;
4519}
4520
4521/**
4522 * sys_rt_sigsuspend - replace the signal mask for a value with the
4523 * @unewset value until a signal is received
4524 * @unewset: new signal mask value
4525 * @sigsetsize: size of sigset_t type
4526 */
4527SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4528{
4529 sigset_t newset;
4530
4531 /* XXX: Don't preclude handling different sized sigset_t's. */
4532 if (sigsetsize != sizeof(sigset_t))
4533 return -EINVAL;
4534
4535 if (copy_from_user(&newset, unewset, sizeof(newset)))
4536 return -EFAULT;
4537 return sigsuspend(&newset);
4538}
4539
4540#ifdef CONFIG_COMPAT
4541COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4542{
4543 sigset_t newset;
4544
4545 /* XXX: Don't preclude handling different sized sigset_t's. */
4546 if (sigsetsize != sizeof(sigset_t))
4547 return -EINVAL;
4548
4549 if (get_compat_sigset(&newset, unewset))
4550 return -EFAULT;
4551 return sigsuspend(&newset);
4552}
4553#endif
4554
4555#ifdef CONFIG_OLD_SIGSUSPEND
4556SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4557{
4558 sigset_t blocked;
4559 siginitset(&blocked, mask);
4560 return sigsuspend(&blocked);
4561}
4562#endif
4563#ifdef CONFIG_OLD_SIGSUSPEND3
4564SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4565{
4566 sigset_t blocked;
4567 siginitset(&blocked, mask);
4568 return sigsuspend(&blocked);
4569}
4570#endif
4571
4572__weak const char *arch_vma_name(struct vm_area_struct *vma)
4573{
4574 return NULL;
4575}
4576
4577static inline void siginfo_buildtime_checks(void)
4578{
4579 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4580
4581 /* Verify the offsets in the two siginfos match */
4582#define CHECK_OFFSET(field) \
4583 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4584
4585 /* kill */
4586 CHECK_OFFSET(si_pid);
4587 CHECK_OFFSET(si_uid);
4588
4589 /* timer */
4590 CHECK_OFFSET(si_tid);
4591 CHECK_OFFSET(si_overrun);
4592 CHECK_OFFSET(si_value);
4593
4594 /* rt */
4595 CHECK_OFFSET(si_pid);
4596 CHECK_OFFSET(si_uid);
4597 CHECK_OFFSET(si_value);
4598
4599 /* sigchld */
4600 CHECK_OFFSET(si_pid);
4601 CHECK_OFFSET(si_uid);
4602 CHECK_OFFSET(si_status);
4603 CHECK_OFFSET(si_utime);
4604 CHECK_OFFSET(si_stime);
4605
4606 /* sigfault */
4607 CHECK_OFFSET(si_addr);
4608 CHECK_OFFSET(si_trapno);
4609 CHECK_OFFSET(si_addr_lsb);
4610 CHECK_OFFSET(si_lower);
4611 CHECK_OFFSET(si_upper);
4612 CHECK_OFFSET(si_pkey);
4613 CHECK_OFFSET(si_perf_data);
4614 CHECK_OFFSET(si_perf_type);
4615
4616 /* sigpoll */
4617 CHECK_OFFSET(si_band);
4618 CHECK_OFFSET(si_fd);
4619
4620 /* sigsys */
4621 CHECK_OFFSET(si_call_addr);
4622 CHECK_OFFSET(si_syscall);
4623 CHECK_OFFSET(si_arch);
4624#undef CHECK_OFFSET
4625
4626 /* usb asyncio */
4627 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4628 offsetof(struct siginfo, si_addr));
4629 if (sizeof(int) == sizeof(void __user *)) {
4630 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4631 sizeof(void __user *));
4632 } else {
4633 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4634 sizeof_field(struct siginfo, si_uid)) !=
4635 sizeof(void __user *));
4636 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4637 offsetof(struct siginfo, si_uid));
4638 }
4639#ifdef CONFIG_COMPAT
4640 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4641 offsetof(struct compat_siginfo, si_addr));
4642 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4643 sizeof(compat_uptr_t));
4644 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4645 sizeof_field(struct siginfo, si_pid));
4646#endif
4647}
4648
4649void __init signals_init(void)
4650{
4651 siginfo_buildtime_checks();
4652
4653 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4654}
4655
4656#ifdef CONFIG_KGDB_KDB
4657#include <linux/kdb.h>
4658/*
4659 * kdb_send_sig - Allows kdb to send signals without exposing
4660 * signal internals. This function checks if the required locks are
4661 * available before calling the main signal code, to avoid kdb
4662 * deadlocks.
4663 */
4664void kdb_send_sig(struct task_struct *t, int sig)
4665{
4666 static struct task_struct *kdb_prev_t;
4667 int new_t, ret;
4668 if (!spin_trylock(&t->sighand->siglock)) {
4669 kdb_printf("Can't do kill command now.\n"
4670 "The sigmask lock is held somewhere else in "
4671 "kernel, try again later\n");
4672 return;
4673 }
4674 new_t = kdb_prev_t != t;
4675 kdb_prev_t = t;
4676 if (!task_is_running(t) && new_t) {
4677 spin_unlock(&t->sighand->siglock);
4678 kdb_printf("Process is not RUNNING, sending a signal from "
4679 "kdb risks deadlock\n"
4680 "on the run queue locks. "
4681 "The signal has _not_ been sent.\n"
4682 "Reissue the kill command if you want to risk "
4683 "the deadlock.\n");
4684 return;
4685 }
4686 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4687 spin_unlock(&t->sighand->siglock);
4688 if (ret)
4689 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4690 sig, t->pid);
4691 else
4692 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4693}
4694#endif /* CONFIG_KGDB_KDB */