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