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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
12 */
13
14#include <linux/slab.h>
15#include <linux/export.h>
16#include <linux/init.h>
17#include <linux/sched/mm.h>
18#include <linux/sched/user.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/sched/cputime.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/mm.h>
26#include <linux/proc_fs.h>
27#include <linux/tty.h>
28#include <linux/binfmts.h>
29#include <linux/coredump.h>
30#include <linux/security.h>
31#include <linux/syscalls.h>
32#include <linux/ptrace.h>
33#include <linux/signal.h>
34#include <linux/signalfd.h>
35#include <linux/ratelimit.h>
36#include <linux/task_work.h>
37#include <linux/capability.h>
38#include <linux/freezer.h>
39#include <linux/pid_namespace.h>
40#include <linux/nsproxy.h>
41#include <linux/user_namespace.h>
42#include <linux/uprobes.h>
43#include <linux/compat.h>
44#include <linux/cn_proc.h>
45#include <linux/compiler.h>
46#include <linux/posix-timers.h>
47#include <linux/cgroup.h>
48#include <linux/audit.h>
49#include <linux/sysctl.h>
50
51#define CREATE_TRACE_POINTS
52#include <trace/events/signal.h>
53
54#include <asm/param.h>
55#include <linux/uaccess.h>
56#include <asm/unistd.h>
57#include <asm/siginfo.h>
58#include <asm/cacheflush.h>
59#include <asm/syscall.h> /* for syscall_get_* */
60
61/*
62 * SLAB caches for signal bits.
63 */
64
65static struct kmem_cache *sigqueue_cachep;
66
67int print_fatal_signals __read_mostly;
68
69static void __user *sig_handler(struct task_struct *t, int sig)
70{
71 return t->sighand->action[sig - 1].sa.sa_handler;
72}
73
74static inline bool sig_handler_ignored(void __user *handler, int sig)
75{
76 /* Is it explicitly or implicitly ignored? */
77 return handler == SIG_IGN ||
78 (handler == SIG_DFL && sig_kernel_ignore(sig));
79}
80
81static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
82{
83 void __user *handler;
84
85 handler = sig_handler(t, sig);
86
87 /* SIGKILL and SIGSTOP may not be sent to the global init */
88 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
89 return true;
90
91 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
92 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
93 return true;
94
95 /* Only allow kernel generated signals to this kthread */
96 if (unlikely((t->flags & PF_KTHREAD) &&
97 (handler == SIG_KTHREAD_KERNEL) && !force))
98 return true;
99
100 return sig_handler_ignored(handler, sig);
101}
102
103static bool sig_ignored(struct task_struct *t, int sig, bool force)
104{
105 /*
106 * Blocked signals are never ignored, since the
107 * signal handler may change by the time it is
108 * unblocked.
109 */
110 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
111 return false;
112
113 /*
114 * Tracers may want to know about even ignored signal unless it
115 * is SIGKILL which can't be reported anyway but can be ignored
116 * by SIGNAL_UNKILLABLE task.
117 */
118 if (t->ptrace && sig != SIGKILL)
119 return false;
120
121 return sig_task_ignored(t, sig, force);
122}
123
124/*
125 * Re-calculate pending state from the set of locally pending
126 * signals, globally pending signals, and blocked signals.
127 */
128static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
129{
130 unsigned long ready;
131 long i;
132
133 switch (_NSIG_WORDS) {
134 default:
135 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
136 ready |= signal->sig[i] &~ blocked->sig[i];
137 break;
138
139 case 4: ready = signal->sig[3] &~ blocked->sig[3];
140 ready |= signal->sig[2] &~ blocked->sig[2];
141 ready |= signal->sig[1] &~ blocked->sig[1];
142 ready |= signal->sig[0] &~ blocked->sig[0];
143 break;
144
145 case 2: ready = signal->sig[1] &~ blocked->sig[1];
146 ready |= signal->sig[0] &~ blocked->sig[0];
147 break;
148
149 case 1: ready = signal->sig[0] &~ blocked->sig[0];
150 }
151 return ready != 0;
152}
153
154#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
155
156static bool recalc_sigpending_tsk(struct task_struct *t)
157{
158 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
159 PENDING(&t->pending, &t->blocked) ||
160 PENDING(&t->signal->shared_pending, &t->blocked) ||
161 cgroup_task_frozen(t)) {
162 set_tsk_thread_flag(t, TIF_SIGPENDING);
163 return true;
164 }
165
166 /*
167 * We must never clear the flag in another thread, or in current
168 * when it's possible the current syscall is returning -ERESTART*.
169 * So we don't clear it here, and only callers who know they should do.
170 */
171 return false;
172}
173
174void recalc_sigpending(void)
175{
176 if (!recalc_sigpending_tsk(current) && !freezing(current))
177 clear_thread_flag(TIF_SIGPENDING);
178
179}
180EXPORT_SYMBOL(recalc_sigpending);
181
182void calculate_sigpending(void)
183{
184 /* Have any signals or users of TIF_SIGPENDING been delayed
185 * until after fork?
186 */
187 spin_lock_irq(¤t->sighand->siglock);
188 set_tsk_thread_flag(current, TIF_SIGPENDING);
189 recalc_sigpending();
190 spin_unlock_irq(¤t->sighand->siglock);
191}
192
193/* Given the mask, find the first available signal that should be serviced. */
194
195#define SYNCHRONOUS_MASK \
196 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
197 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
198
199int next_signal(struct sigpending *pending, sigset_t *mask)
200{
201 unsigned long i, *s, *m, x;
202 int sig = 0;
203
204 s = pending->signal.sig;
205 m = mask->sig;
206
207 /*
208 * Handle the first word specially: it contains the
209 * synchronous signals that need to be dequeued first.
210 */
211 x = *s &~ *m;
212 if (x) {
213 if (x & SYNCHRONOUS_MASK)
214 x &= SYNCHRONOUS_MASK;
215 sig = ffz(~x) + 1;
216 return sig;
217 }
218
219 switch (_NSIG_WORDS) {
220 default:
221 for (i = 1; i < _NSIG_WORDS; ++i) {
222 x = *++s &~ *++m;
223 if (!x)
224 continue;
225 sig = ffz(~x) + i*_NSIG_BPW + 1;
226 break;
227 }
228 break;
229
230 case 2:
231 x = s[1] &~ m[1];
232 if (!x)
233 break;
234 sig = ffz(~x) + _NSIG_BPW + 1;
235 break;
236
237 case 1:
238 /* Nothing to do */
239 break;
240 }
241
242 return sig;
243}
244
245static inline void print_dropped_signal(int sig)
246{
247 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
248
249 if (!print_fatal_signals)
250 return;
251
252 if (!__ratelimit(&ratelimit_state))
253 return;
254
255 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
256 current->comm, current->pid, sig);
257}
258
259/**
260 * task_set_jobctl_pending - set jobctl pending bits
261 * @task: target task
262 * @mask: pending bits to set
263 *
264 * Clear @mask from @task->jobctl. @mask must be subset of
265 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
266 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
267 * cleared. If @task is already being killed or exiting, this function
268 * becomes noop.
269 *
270 * CONTEXT:
271 * Must be called with @task->sighand->siglock held.
272 *
273 * RETURNS:
274 * %true if @mask is set, %false if made noop because @task was dying.
275 */
276bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
277{
278 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
279 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
280 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
281
282 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
283 return false;
284
285 if (mask & JOBCTL_STOP_SIGMASK)
286 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
287
288 task->jobctl |= mask;
289 return true;
290}
291
292/**
293 * task_clear_jobctl_trapping - clear jobctl trapping bit
294 * @task: target task
295 *
296 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
297 * Clear it and wake up the ptracer. Note that we don't need any further
298 * locking. @task->siglock guarantees that @task->parent points to the
299 * ptracer.
300 *
301 * CONTEXT:
302 * Must be called with @task->sighand->siglock held.
303 */
304void task_clear_jobctl_trapping(struct task_struct *task)
305{
306 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
307 task->jobctl &= ~JOBCTL_TRAPPING;
308 smp_mb(); /* advised by wake_up_bit() */
309 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
310 }
311}
312
313/**
314 * task_clear_jobctl_pending - clear jobctl pending bits
315 * @task: target task
316 * @mask: pending bits to clear
317 *
318 * Clear @mask from @task->jobctl. @mask must be subset of
319 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
320 * STOP bits are cleared together.
321 *
322 * If clearing of @mask leaves no stop or trap pending, this function calls
323 * task_clear_jobctl_trapping().
324 *
325 * CONTEXT:
326 * Must be called with @task->sighand->siglock held.
327 */
328void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
329{
330 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
331
332 if (mask & JOBCTL_STOP_PENDING)
333 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
334
335 task->jobctl &= ~mask;
336
337 if (!(task->jobctl & JOBCTL_PENDING_MASK))
338 task_clear_jobctl_trapping(task);
339}
340
341/**
342 * task_participate_group_stop - participate in a group stop
343 * @task: task participating in a group stop
344 *
345 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
346 * Group stop states are cleared and the group stop count is consumed if
347 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
348 * stop, the appropriate `SIGNAL_*` flags are set.
349 *
350 * CONTEXT:
351 * Must be called with @task->sighand->siglock held.
352 *
353 * RETURNS:
354 * %true if group stop completion should be notified to the parent, %false
355 * otherwise.
356 */
357static bool task_participate_group_stop(struct task_struct *task)
358{
359 struct signal_struct *sig = task->signal;
360 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
361
362 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
363
364 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
365
366 if (!consume)
367 return false;
368
369 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
370 sig->group_stop_count--;
371
372 /*
373 * Tell the caller to notify completion iff we are entering into a
374 * fresh group stop. Read comment in do_signal_stop() for details.
375 */
376 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
377 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
378 return true;
379 }
380 return false;
381}
382
383void task_join_group_stop(struct task_struct *task)
384{
385 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
386 struct signal_struct *sig = current->signal;
387
388 if (sig->group_stop_count) {
389 sig->group_stop_count++;
390 mask |= JOBCTL_STOP_CONSUME;
391 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
392 return;
393
394 /* Have the new thread join an on-going signal group stop */
395 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
396}
397
398/*
399 * allocate a new signal queue record
400 * - this may be called without locks if and only if t == current, otherwise an
401 * appropriate lock must be held to stop the target task from exiting
402 */
403static struct sigqueue *
404__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
405 int override_rlimit, const unsigned int sigqueue_flags)
406{
407 struct sigqueue *q = NULL;
408 struct ucounts *ucounts;
409 long sigpending;
410
411 /*
412 * Protect access to @t credentials. This can go away when all
413 * callers hold rcu read lock.
414 *
415 * NOTE! A pending signal will hold on to the user refcount,
416 * and we get/put the refcount only when the sigpending count
417 * changes from/to zero.
418 */
419 rcu_read_lock();
420 ucounts = task_ucounts(t);
421 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
422 rcu_read_unlock();
423 if (!sigpending)
424 return NULL;
425
426 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
427 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
428 } else {
429 print_dropped_signal(sig);
430 }
431
432 if (unlikely(q == NULL)) {
433 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
434 } else {
435 INIT_LIST_HEAD(&q->list);
436 q->flags = sigqueue_flags;
437 q->ucounts = ucounts;
438 }
439 return q;
440}
441
442static void __sigqueue_free(struct sigqueue *q)
443{
444 if (q->flags & SIGQUEUE_PREALLOC)
445 return;
446 if (q->ucounts) {
447 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
448 q->ucounts = NULL;
449 }
450 kmem_cache_free(sigqueue_cachep, q);
451}
452
453void flush_sigqueue(struct sigpending *queue)
454{
455 struct sigqueue *q;
456
457 sigemptyset(&queue->signal);
458 while (!list_empty(&queue->list)) {
459 q = list_entry(queue->list.next, struct sigqueue , list);
460 list_del_init(&q->list);
461 __sigqueue_free(q);
462 }
463}
464
465/*
466 * Flush all pending signals for this kthread.
467 */
468void flush_signals(struct task_struct *t)
469{
470 unsigned long flags;
471
472 spin_lock_irqsave(&t->sighand->siglock, flags);
473 clear_tsk_thread_flag(t, TIF_SIGPENDING);
474 flush_sigqueue(&t->pending);
475 flush_sigqueue(&t->signal->shared_pending);
476 spin_unlock_irqrestore(&t->sighand->siglock, flags);
477}
478EXPORT_SYMBOL(flush_signals);
479
480#ifdef CONFIG_POSIX_TIMERS
481static void __flush_itimer_signals(struct sigpending *pending)
482{
483 sigset_t signal, retain;
484 struct sigqueue *q, *n;
485
486 signal = pending->signal;
487 sigemptyset(&retain);
488
489 list_for_each_entry_safe(q, n, &pending->list, list) {
490 int sig = q->info.si_signo;
491
492 if (likely(q->info.si_code != SI_TIMER)) {
493 sigaddset(&retain, sig);
494 } else {
495 sigdelset(&signal, sig);
496 list_del_init(&q->list);
497 __sigqueue_free(q);
498 }
499 }
500
501 sigorsets(&pending->signal, &signal, &retain);
502}
503
504void flush_itimer_signals(void)
505{
506 struct task_struct *tsk = current;
507 unsigned long flags;
508
509 spin_lock_irqsave(&tsk->sighand->siglock, flags);
510 __flush_itimer_signals(&tsk->pending);
511 __flush_itimer_signals(&tsk->signal->shared_pending);
512 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
513}
514#endif
515
516void ignore_signals(struct task_struct *t)
517{
518 int i;
519
520 for (i = 0; i < _NSIG; ++i)
521 t->sighand->action[i].sa.sa_handler = SIG_IGN;
522
523 flush_signals(t);
524}
525
526/*
527 * Flush all handlers for a task.
528 */
529
530void
531flush_signal_handlers(struct task_struct *t, int force_default)
532{
533 int i;
534 struct k_sigaction *ka = &t->sighand->action[0];
535 for (i = _NSIG ; i != 0 ; i--) {
536 if (force_default || ka->sa.sa_handler != SIG_IGN)
537 ka->sa.sa_handler = SIG_DFL;
538 ka->sa.sa_flags = 0;
539#ifdef __ARCH_HAS_SA_RESTORER
540 ka->sa.sa_restorer = NULL;
541#endif
542 sigemptyset(&ka->sa.sa_mask);
543 ka++;
544 }
545}
546
547bool unhandled_signal(struct task_struct *tsk, int sig)
548{
549 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
550 if (is_global_init(tsk))
551 return true;
552
553 if (handler != SIG_IGN && handler != SIG_DFL)
554 return false;
555
556 /* If dying, we handle all new signals by ignoring them */
557 if (fatal_signal_pending(tsk))
558 return false;
559
560 /* if ptraced, let the tracer determine */
561 return !tsk->ptrace;
562}
563
564static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
565 bool *resched_timer)
566{
567 struct sigqueue *q, *first = NULL;
568
569 /*
570 * Collect the siginfo appropriate to this signal. Check if
571 * there is another siginfo for the same signal.
572 */
573 list_for_each_entry(q, &list->list, list) {
574 if (q->info.si_signo == sig) {
575 if (first)
576 goto still_pending;
577 first = q;
578 }
579 }
580
581 sigdelset(&list->signal, sig);
582
583 if (first) {
584still_pending:
585 list_del_init(&first->list);
586 copy_siginfo(info, &first->info);
587
588 *resched_timer =
589 (first->flags & SIGQUEUE_PREALLOC) &&
590 (info->si_code == SI_TIMER) &&
591 (info->si_sys_private);
592
593 __sigqueue_free(first);
594 } else {
595 /*
596 * Ok, it wasn't in the queue. This must be
597 * a fast-pathed signal or we must have been
598 * out of queue space. So zero out the info.
599 */
600 clear_siginfo(info);
601 info->si_signo = sig;
602 info->si_errno = 0;
603 info->si_code = SI_USER;
604 info->si_pid = 0;
605 info->si_uid = 0;
606 }
607}
608
609static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
610 kernel_siginfo_t *info, bool *resched_timer)
611{
612 int sig = next_signal(pending, mask);
613
614 if (sig)
615 collect_signal(sig, pending, info, resched_timer);
616 return sig;
617}
618
619/*
620 * Dequeue a signal and return the element to the caller, which is
621 * expected to free it.
622 *
623 * All callers have to hold the siglock.
624 */
625int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
626 kernel_siginfo_t *info, enum pid_type *type)
627{
628 bool resched_timer = false;
629 int signr;
630
631 /* We only dequeue private signals from ourselves, we don't let
632 * signalfd steal them
633 */
634 *type = PIDTYPE_PID;
635 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
636 if (!signr) {
637 *type = PIDTYPE_TGID;
638 signr = __dequeue_signal(&tsk->signal->shared_pending,
639 mask, info, &resched_timer);
640#ifdef CONFIG_POSIX_TIMERS
641 /*
642 * itimer signal ?
643 *
644 * itimers are process shared and we restart periodic
645 * itimers in the signal delivery path to prevent DoS
646 * attacks in the high resolution timer case. This is
647 * compliant with the old way of self-restarting
648 * itimers, as the SIGALRM is a legacy signal and only
649 * queued once. Changing the restart behaviour to
650 * restart the timer in the signal dequeue path is
651 * reducing the timer noise on heavy loaded !highres
652 * systems too.
653 */
654 if (unlikely(signr == SIGALRM)) {
655 struct hrtimer *tmr = &tsk->signal->real_timer;
656
657 if (!hrtimer_is_queued(tmr) &&
658 tsk->signal->it_real_incr != 0) {
659 hrtimer_forward(tmr, tmr->base->get_time(),
660 tsk->signal->it_real_incr);
661 hrtimer_restart(tmr);
662 }
663 }
664#endif
665 }
666
667 recalc_sigpending();
668 if (!signr)
669 return 0;
670
671 if (unlikely(sig_kernel_stop(signr))) {
672 /*
673 * Set a marker that we have dequeued a stop signal. Our
674 * caller might release the siglock and then the pending
675 * stop signal it is about to process is no longer in the
676 * pending bitmasks, but must still be cleared by a SIGCONT
677 * (and overruled by a SIGKILL). So those cases clear this
678 * shared flag after we've set it. Note that this flag may
679 * remain set after the signal we return is ignored or
680 * handled. That doesn't matter because its only purpose
681 * is to alert stop-signal processing code when another
682 * processor has come along and cleared the flag.
683 */
684 current->jobctl |= JOBCTL_STOP_DEQUEUED;
685 }
686#ifdef CONFIG_POSIX_TIMERS
687 if (resched_timer) {
688 /*
689 * Release the siglock to ensure proper locking order
690 * of timer locks outside of siglocks. Note, we leave
691 * irqs disabled here, since the posix-timers code is
692 * about to disable them again anyway.
693 */
694 spin_unlock(&tsk->sighand->siglock);
695 posixtimer_rearm(info);
696 spin_lock(&tsk->sighand->siglock);
697
698 /* Don't expose the si_sys_private value to userspace */
699 info->si_sys_private = 0;
700 }
701#endif
702 return signr;
703}
704EXPORT_SYMBOL_GPL(dequeue_signal);
705
706static int dequeue_synchronous_signal(kernel_siginfo_t *info)
707{
708 struct task_struct *tsk = current;
709 struct sigpending *pending = &tsk->pending;
710 struct sigqueue *q, *sync = NULL;
711
712 /*
713 * Might a synchronous signal be in the queue?
714 */
715 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
716 return 0;
717
718 /*
719 * Return the first synchronous signal in the queue.
720 */
721 list_for_each_entry(q, &pending->list, list) {
722 /* Synchronous signals have a positive si_code */
723 if ((q->info.si_code > SI_USER) &&
724 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
725 sync = q;
726 goto next;
727 }
728 }
729 return 0;
730next:
731 /*
732 * Check if there is another siginfo for the same signal.
733 */
734 list_for_each_entry_continue(q, &pending->list, list) {
735 if (q->info.si_signo == sync->info.si_signo)
736 goto still_pending;
737 }
738
739 sigdelset(&pending->signal, sync->info.si_signo);
740 recalc_sigpending();
741still_pending:
742 list_del_init(&sync->list);
743 copy_siginfo(info, &sync->info);
744 __sigqueue_free(sync);
745 return info->si_signo;
746}
747
748/*
749 * Tell a process that it has a new active signal..
750 *
751 * NOTE! we rely on the previous spin_lock to
752 * lock interrupts for us! We can only be called with
753 * "siglock" held, and the local interrupt must
754 * have been disabled when that got acquired!
755 *
756 * No need to set need_resched since signal event passing
757 * goes through ->blocked
758 */
759void signal_wake_up_state(struct task_struct *t, unsigned int state)
760{
761 lockdep_assert_held(&t->sighand->siglock);
762
763 set_tsk_thread_flag(t, TIF_SIGPENDING);
764
765 /*
766 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
767 * case. We don't check t->state here because there is a race with it
768 * executing another processor and just now entering stopped state.
769 * By using wake_up_state, we ensure the process will wake up and
770 * handle its death signal.
771 */
772 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
773 kick_process(t);
774}
775
776/*
777 * Remove signals in mask from the pending set and queue.
778 * Returns 1 if any signals were found.
779 *
780 * All callers must be holding the siglock.
781 */
782static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
783{
784 struct sigqueue *q, *n;
785 sigset_t m;
786
787 sigandsets(&m, mask, &s->signal);
788 if (sigisemptyset(&m))
789 return;
790
791 sigandnsets(&s->signal, &s->signal, mask);
792 list_for_each_entry_safe(q, n, &s->list, list) {
793 if (sigismember(mask, q->info.si_signo)) {
794 list_del_init(&q->list);
795 __sigqueue_free(q);
796 }
797 }
798}
799
800static inline int is_si_special(const struct kernel_siginfo *info)
801{
802 return info <= SEND_SIG_PRIV;
803}
804
805static inline bool si_fromuser(const struct kernel_siginfo *info)
806{
807 return info == SEND_SIG_NOINFO ||
808 (!is_si_special(info) && SI_FROMUSER(info));
809}
810
811/*
812 * called with RCU read lock from check_kill_permission()
813 */
814static bool kill_ok_by_cred(struct task_struct *t)
815{
816 const struct cred *cred = current_cred();
817 const struct cred *tcred = __task_cred(t);
818
819 return uid_eq(cred->euid, tcred->suid) ||
820 uid_eq(cred->euid, tcred->uid) ||
821 uid_eq(cred->uid, tcred->suid) ||
822 uid_eq(cred->uid, tcred->uid) ||
823 ns_capable(tcred->user_ns, CAP_KILL);
824}
825
826/*
827 * Bad permissions for sending the signal
828 * - the caller must hold the RCU read lock
829 */
830static int check_kill_permission(int sig, struct kernel_siginfo *info,
831 struct task_struct *t)
832{
833 struct pid *sid;
834 int error;
835
836 if (!valid_signal(sig))
837 return -EINVAL;
838
839 if (!si_fromuser(info))
840 return 0;
841
842 error = audit_signal_info(sig, t); /* Let audit system see the signal */
843 if (error)
844 return error;
845
846 if (!same_thread_group(current, t) &&
847 !kill_ok_by_cred(t)) {
848 switch (sig) {
849 case SIGCONT:
850 sid = task_session(t);
851 /*
852 * We don't return the error if sid == NULL. The
853 * task was unhashed, the caller must notice this.
854 */
855 if (!sid || sid == task_session(current))
856 break;
857 fallthrough;
858 default:
859 return -EPERM;
860 }
861 }
862
863 return security_task_kill(t, info, sig, NULL);
864}
865
866/**
867 * ptrace_trap_notify - schedule trap to notify ptracer
868 * @t: tracee wanting to notify tracer
869 *
870 * This function schedules sticky ptrace trap which is cleared on the next
871 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
872 * ptracer.
873 *
874 * If @t is running, STOP trap will be taken. If trapped for STOP and
875 * ptracer is listening for events, tracee is woken up so that it can
876 * re-trap for the new event. If trapped otherwise, STOP trap will be
877 * eventually taken without returning to userland after the existing traps
878 * are finished by PTRACE_CONT.
879 *
880 * CONTEXT:
881 * Must be called with @task->sighand->siglock held.
882 */
883static void ptrace_trap_notify(struct task_struct *t)
884{
885 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
886 lockdep_assert_held(&t->sighand->siglock);
887
888 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
889 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
890}
891
892/*
893 * Handle magic process-wide effects of stop/continue signals. Unlike
894 * the signal actions, these happen immediately at signal-generation
895 * time regardless of blocking, ignoring, or handling. This does the
896 * actual continuing for SIGCONT, but not the actual stopping for stop
897 * signals. The process stop is done as a signal action for SIG_DFL.
898 *
899 * Returns true if the signal should be actually delivered, otherwise
900 * it should be dropped.
901 */
902static bool prepare_signal(int sig, struct task_struct *p, bool force)
903{
904 struct signal_struct *signal = p->signal;
905 struct task_struct *t;
906 sigset_t flush;
907
908 if (signal->flags & SIGNAL_GROUP_EXIT) {
909 if (signal->core_state)
910 return sig == SIGKILL;
911 /*
912 * The process is in the middle of dying, drop the signal.
913 */
914 return false;
915 } else if (sig_kernel_stop(sig)) {
916 /*
917 * This is a stop signal. Remove SIGCONT from all queues.
918 */
919 siginitset(&flush, sigmask(SIGCONT));
920 flush_sigqueue_mask(&flush, &signal->shared_pending);
921 for_each_thread(p, t)
922 flush_sigqueue_mask(&flush, &t->pending);
923 } else if (sig == SIGCONT) {
924 unsigned int why;
925 /*
926 * Remove all stop signals from all queues, wake all threads.
927 */
928 siginitset(&flush, SIG_KERNEL_STOP_MASK);
929 flush_sigqueue_mask(&flush, &signal->shared_pending);
930 for_each_thread(p, t) {
931 flush_sigqueue_mask(&flush, &t->pending);
932 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
933 if (likely(!(t->ptrace & PT_SEIZED))) {
934 t->jobctl &= ~JOBCTL_STOPPED;
935 wake_up_state(t, __TASK_STOPPED);
936 } else
937 ptrace_trap_notify(t);
938 }
939
940 /*
941 * Notify the parent with CLD_CONTINUED if we were stopped.
942 *
943 * If we were in the middle of a group stop, we pretend it
944 * was already finished, and then continued. Since SIGCHLD
945 * doesn't queue we report only CLD_STOPPED, as if the next
946 * CLD_CONTINUED was dropped.
947 */
948 why = 0;
949 if (signal->flags & SIGNAL_STOP_STOPPED)
950 why |= SIGNAL_CLD_CONTINUED;
951 else if (signal->group_stop_count)
952 why |= SIGNAL_CLD_STOPPED;
953
954 if (why) {
955 /*
956 * The first thread which returns from do_signal_stop()
957 * will take ->siglock, notice SIGNAL_CLD_MASK, and
958 * notify its parent. See get_signal().
959 */
960 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
961 signal->group_stop_count = 0;
962 signal->group_exit_code = 0;
963 }
964 }
965
966 return !sig_ignored(p, sig, force);
967}
968
969/*
970 * Test if P wants to take SIG. After we've checked all threads with this,
971 * it's equivalent to finding no threads not blocking SIG. Any threads not
972 * blocking SIG were ruled out because they are not running and already
973 * have pending signals. Such threads will dequeue from the shared queue
974 * as soon as they're available, so putting the signal on the shared queue
975 * will be equivalent to sending it to one such thread.
976 */
977static inline bool wants_signal(int sig, struct task_struct *p)
978{
979 if (sigismember(&p->blocked, sig))
980 return false;
981
982 if (p->flags & PF_EXITING)
983 return false;
984
985 if (sig == SIGKILL)
986 return true;
987
988 if (task_is_stopped_or_traced(p))
989 return false;
990
991 return task_curr(p) || !task_sigpending(p);
992}
993
994static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
995{
996 struct signal_struct *signal = p->signal;
997 struct task_struct *t;
998
999 /*
1000 * Now find a thread we can wake up to take the signal off the queue.
1001 *
1002 * Try the suggested task first (may or may not be the main thread).
1003 */
1004 if (wants_signal(sig, p))
1005 t = p;
1006 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1007 /*
1008 * There is just one thread and it does not need to be woken.
1009 * It will dequeue unblocked signals before it runs again.
1010 */
1011 return;
1012 else {
1013 /*
1014 * Otherwise try to find a suitable thread.
1015 */
1016 t = signal->curr_target;
1017 while (!wants_signal(sig, t)) {
1018 t = next_thread(t);
1019 if (t == signal->curr_target)
1020 /*
1021 * No thread needs to be woken.
1022 * Any eligible threads will see
1023 * the signal in the queue soon.
1024 */
1025 return;
1026 }
1027 signal->curr_target = t;
1028 }
1029
1030 /*
1031 * Found a killable thread. If the signal will be fatal,
1032 * then start taking the whole group down immediately.
1033 */
1034 if (sig_fatal(p, sig) &&
1035 (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1036 !sigismember(&t->real_blocked, sig) &&
1037 (sig == SIGKILL || !p->ptrace)) {
1038 /*
1039 * This signal will be fatal to the whole group.
1040 */
1041 if (!sig_kernel_coredump(sig)) {
1042 /*
1043 * Start a group exit and wake everybody up.
1044 * This way we don't have other threads
1045 * running and doing things after a slower
1046 * thread has the fatal signal pending.
1047 */
1048 signal->flags = SIGNAL_GROUP_EXIT;
1049 signal->group_exit_code = sig;
1050 signal->group_stop_count = 0;
1051 __for_each_thread(signal, t) {
1052 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1053 sigaddset(&t->pending.signal, SIGKILL);
1054 signal_wake_up(t, 1);
1055 }
1056 return;
1057 }
1058 }
1059
1060 /*
1061 * The signal is already in the shared-pending queue.
1062 * Tell the chosen thread to wake up and dequeue it.
1063 */
1064 signal_wake_up(t, sig == SIGKILL);
1065 return;
1066}
1067
1068static inline bool legacy_queue(struct sigpending *signals, int sig)
1069{
1070 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1071}
1072
1073static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1074 struct task_struct *t, enum pid_type type, bool force)
1075{
1076 struct sigpending *pending;
1077 struct sigqueue *q;
1078 int override_rlimit;
1079 int ret = 0, result;
1080
1081 lockdep_assert_held(&t->sighand->siglock);
1082
1083 result = TRACE_SIGNAL_IGNORED;
1084 if (!prepare_signal(sig, t, force))
1085 goto ret;
1086
1087 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1088 /*
1089 * Short-circuit ignored signals and support queuing
1090 * exactly one non-rt signal, so that we can get more
1091 * detailed information about the cause of the signal.
1092 */
1093 result = TRACE_SIGNAL_ALREADY_PENDING;
1094 if (legacy_queue(pending, sig))
1095 goto ret;
1096
1097 result = TRACE_SIGNAL_DELIVERED;
1098 /*
1099 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1100 */
1101 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1102 goto out_set;
1103
1104 /*
1105 * Real-time signals must be queued if sent by sigqueue, or
1106 * some other real-time mechanism. It is implementation
1107 * defined whether kill() does so. We attempt to do so, on
1108 * the principle of least surprise, but since kill is not
1109 * allowed to fail with EAGAIN when low on memory we just
1110 * make sure at least one signal gets delivered and don't
1111 * pass on the info struct.
1112 */
1113 if (sig < SIGRTMIN)
1114 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1115 else
1116 override_rlimit = 0;
1117
1118 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1119
1120 if (q) {
1121 list_add_tail(&q->list, &pending->list);
1122 switch ((unsigned long) info) {
1123 case (unsigned long) SEND_SIG_NOINFO:
1124 clear_siginfo(&q->info);
1125 q->info.si_signo = sig;
1126 q->info.si_errno = 0;
1127 q->info.si_code = SI_USER;
1128 q->info.si_pid = task_tgid_nr_ns(current,
1129 task_active_pid_ns(t));
1130 rcu_read_lock();
1131 q->info.si_uid =
1132 from_kuid_munged(task_cred_xxx(t, user_ns),
1133 current_uid());
1134 rcu_read_unlock();
1135 break;
1136 case (unsigned long) SEND_SIG_PRIV:
1137 clear_siginfo(&q->info);
1138 q->info.si_signo = sig;
1139 q->info.si_errno = 0;
1140 q->info.si_code = SI_KERNEL;
1141 q->info.si_pid = 0;
1142 q->info.si_uid = 0;
1143 break;
1144 default:
1145 copy_siginfo(&q->info, info);
1146 break;
1147 }
1148 } else if (!is_si_special(info) &&
1149 sig >= SIGRTMIN && info->si_code != SI_USER) {
1150 /*
1151 * Queue overflow, abort. We may abort if the
1152 * signal was rt and sent by user using something
1153 * other than kill().
1154 */
1155 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1156 ret = -EAGAIN;
1157 goto ret;
1158 } else {
1159 /*
1160 * This is a silent loss of information. We still
1161 * send the signal, but the *info bits are lost.
1162 */
1163 result = TRACE_SIGNAL_LOSE_INFO;
1164 }
1165
1166out_set:
1167 signalfd_notify(t, sig);
1168 sigaddset(&pending->signal, sig);
1169
1170 /* Let multiprocess signals appear after on-going forks */
1171 if (type > PIDTYPE_TGID) {
1172 struct multiprocess_signals *delayed;
1173 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1174 sigset_t *signal = &delayed->signal;
1175 /* Can't queue both a stop and a continue signal */
1176 if (sig == SIGCONT)
1177 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1178 else if (sig_kernel_stop(sig))
1179 sigdelset(signal, SIGCONT);
1180 sigaddset(signal, sig);
1181 }
1182 }
1183
1184 complete_signal(sig, t, type);
1185ret:
1186 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1187 return ret;
1188}
1189
1190static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1191{
1192 bool ret = false;
1193 switch (siginfo_layout(info->si_signo, info->si_code)) {
1194 case SIL_KILL:
1195 case SIL_CHLD:
1196 case SIL_RT:
1197 ret = true;
1198 break;
1199 case SIL_TIMER:
1200 case SIL_POLL:
1201 case SIL_FAULT:
1202 case SIL_FAULT_TRAPNO:
1203 case SIL_FAULT_MCEERR:
1204 case SIL_FAULT_BNDERR:
1205 case SIL_FAULT_PKUERR:
1206 case SIL_FAULT_PERF_EVENT:
1207 case SIL_SYS:
1208 ret = false;
1209 break;
1210 }
1211 return ret;
1212}
1213
1214int send_signal_locked(int sig, struct kernel_siginfo *info,
1215 struct task_struct *t, enum pid_type type)
1216{
1217 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1218 bool force = false;
1219
1220 if (info == SEND_SIG_NOINFO) {
1221 /* Force if sent from an ancestor pid namespace */
1222 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1223 } else if (info == SEND_SIG_PRIV) {
1224 /* Don't ignore kernel generated signals */
1225 force = true;
1226 } else if (has_si_pid_and_uid(info)) {
1227 /* SIGKILL and SIGSTOP is special or has ids */
1228 struct user_namespace *t_user_ns;
1229
1230 rcu_read_lock();
1231 t_user_ns = task_cred_xxx(t, user_ns);
1232 if (current_user_ns() != t_user_ns) {
1233 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1234 info->si_uid = from_kuid_munged(t_user_ns, uid);
1235 }
1236 rcu_read_unlock();
1237
1238 /* A kernel generated signal? */
1239 force = (info->si_code == SI_KERNEL);
1240
1241 /* From an ancestor pid namespace? */
1242 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1243 info->si_pid = 0;
1244 force = true;
1245 }
1246 }
1247 return __send_signal_locked(sig, info, t, type, force);
1248}
1249
1250static void print_fatal_signal(int signr)
1251{
1252 struct pt_regs *regs = task_pt_regs(current);
1253 struct file *exe_file;
1254
1255 exe_file = get_task_exe_file(current);
1256 if (exe_file) {
1257 pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1258 exe_file, current->comm, signr);
1259 fput(exe_file);
1260 } else {
1261 pr_info("%s: potentially unexpected fatal signal %d.\n",
1262 current->comm, signr);
1263 }
1264
1265#if defined(__i386__) && !defined(__arch_um__)
1266 pr_info("code at %08lx: ", regs->ip);
1267 {
1268 int i;
1269 for (i = 0; i < 16; i++) {
1270 unsigned char insn;
1271
1272 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1273 break;
1274 pr_cont("%02x ", insn);
1275 }
1276 }
1277 pr_cont("\n");
1278#endif
1279 preempt_disable();
1280 show_regs(regs);
1281 preempt_enable();
1282}
1283
1284static int __init setup_print_fatal_signals(char *str)
1285{
1286 get_option (&str, &print_fatal_signals);
1287
1288 return 1;
1289}
1290
1291__setup("print-fatal-signals=", setup_print_fatal_signals);
1292
1293int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1294 enum pid_type type)
1295{
1296 unsigned long flags;
1297 int ret = -ESRCH;
1298
1299 if (lock_task_sighand(p, &flags)) {
1300 ret = send_signal_locked(sig, info, p, type);
1301 unlock_task_sighand(p, &flags);
1302 }
1303
1304 return ret;
1305}
1306
1307enum sig_handler {
1308 HANDLER_CURRENT, /* If reachable use the current handler */
1309 HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1310 HANDLER_EXIT, /* Only visible as the process exit code */
1311};
1312
1313/*
1314 * Force a signal that the process can't ignore: if necessary
1315 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1316 *
1317 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1318 * since we do not want to have a signal handler that was blocked
1319 * be invoked when user space had explicitly blocked it.
1320 *
1321 * We don't want to have recursive SIGSEGV's etc, for example,
1322 * that is why we also clear SIGNAL_UNKILLABLE.
1323 */
1324static int
1325force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1326 enum sig_handler handler)
1327{
1328 unsigned long int flags;
1329 int ret, blocked, ignored;
1330 struct k_sigaction *action;
1331 int sig = info->si_signo;
1332
1333 spin_lock_irqsave(&t->sighand->siglock, flags);
1334 action = &t->sighand->action[sig-1];
1335 ignored = action->sa.sa_handler == SIG_IGN;
1336 blocked = sigismember(&t->blocked, sig);
1337 if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1338 action->sa.sa_handler = SIG_DFL;
1339 if (handler == HANDLER_EXIT)
1340 action->sa.sa_flags |= SA_IMMUTABLE;
1341 if (blocked)
1342 sigdelset(&t->blocked, sig);
1343 }
1344 /*
1345 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1346 * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1347 */
1348 if (action->sa.sa_handler == SIG_DFL &&
1349 (!t->ptrace || (handler == HANDLER_EXIT)))
1350 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1351 ret = send_signal_locked(sig, info, t, PIDTYPE_PID);
1352 /* This can happen if the signal was already pending and blocked */
1353 if (!task_sigpending(t))
1354 signal_wake_up(t, 0);
1355 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1356
1357 return ret;
1358}
1359
1360int force_sig_info(struct kernel_siginfo *info)
1361{
1362 return force_sig_info_to_task(info, current, HANDLER_CURRENT);
1363}
1364
1365/*
1366 * Nuke all other threads in the group.
1367 */
1368int zap_other_threads(struct task_struct *p)
1369{
1370 struct task_struct *t;
1371 int count = 0;
1372
1373 p->signal->group_stop_count = 0;
1374
1375 for_other_threads(p, t) {
1376 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1377 /* Don't require de_thread to wait for the vhost_worker */
1378 if ((t->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)
1379 count++;
1380
1381 /* Don't bother with already dead threads */
1382 if (t->exit_state)
1383 continue;
1384 sigaddset(&t->pending.signal, SIGKILL);
1385 signal_wake_up(t, 1);
1386 }
1387
1388 return count;
1389}
1390
1391struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1392 unsigned long *flags)
1393{
1394 struct sighand_struct *sighand;
1395
1396 rcu_read_lock();
1397 for (;;) {
1398 sighand = rcu_dereference(tsk->sighand);
1399 if (unlikely(sighand == NULL))
1400 break;
1401
1402 /*
1403 * This sighand can be already freed and even reused, but
1404 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1405 * initializes ->siglock: this slab can't go away, it has
1406 * the same object type, ->siglock can't be reinitialized.
1407 *
1408 * We need to ensure that tsk->sighand is still the same
1409 * after we take the lock, we can race with de_thread() or
1410 * __exit_signal(). In the latter case the next iteration
1411 * must see ->sighand == NULL.
1412 */
1413 spin_lock_irqsave(&sighand->siglock, *flags);
1414 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1415 break;
1416 spin_unlock_irqrestore(&sighand->siglock, *flags);
1417 }
1418 rcu_read_unlock();
1419
1420 return sighand;
1421}
1422
1423#ifdef CONFIG_LOCKDEP
1424void lockdep_assert_task_sighand_held(struct task_struct *task)
1425{
1426 struct sighand_struct *sighand;
1427
1428 rcu_read_lock();
1429 sighand = rcu_dereference(task->sighand);
1430 if (sighand)
1431 lockdep_assert_held(&sighand->siglock);
1432 else
1433 WARN_ON_ONCE(1);
1434 rcu_read_unlock();
1435}
1436#endif
1437
1438/*
1439 * send signal info to all the members of a group
1440 */
1441int group_send_sig_info(int sig, struct kernel_siginfo *info,
1442 struct task_struct *p, enum pid_type type)
1443{
1444 int ret;
1445
1446 rcu_read_lock();
1447 ret = check_kill_permission(sig, info, p);
1448 rcu_read_unlock();
1449
1450 if (!ret && sig)
1451 ret = do_send_sig_info(sig, info, p, type);
1452
1453 return ret;
1454}
1455
1456/*
1457 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1458 * control characters do (^C, ^Z etc)
1459 * - the caller must hold at least a readlock on tasklist_lock
1460 */
1461int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1462{
1463 struct task_struct *p = NULL;
1464 int ret = -ESRCH;
1465
1466 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1467 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1468 /*
1469 * If group_send_sig_info() succeeds at least once ret
1470 * becomes 0 and after that the code below has no effect.
1471 * Otherwise we return the last err or -ESRCH if this
1472 * process group is empty.
1473 */
1474 if (ret)
1475 ret = err;
1476 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1477
1478 return ret;
1479}
1480
1481int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1482{
1483 int error = -ESRCH;
1484 struct task_struct *p;
1485
1486 for (;;) {
1487 rcu_read_lock();
1488 p = pid_task(pid, PIDTYPE_PID);
1489 if (p)
1490 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1491 rcu_read_unlock();
1492 if (likely(!p || error != -ESRCH))
1493 return error;
1494
1495 /*
1496 * The task was unhashed in between, try again. If it
1497 * is dead, pid_task() will return NULL, if we race with
1498 * de_thread() it will find the new leader.
1499 */
1500 }
1501}
1502
1503static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1504{
1505 int error;
1506 rcu_read_lock();
1507 error = kill_pid_info(sig, info, find_vpid(pid));
1508 rcu_read_unlock();
1509 return error;
1510}
1511
1512static inline bool kill_as_cred_perm(const struct cred *cred,
1513 struct task_struct *target)
1514{
1515 const struct cred *pcred = __task_cred(target);
1516
1517 return uid_eq(cred->euid, pcred->suid) ||
1518 uid_eq(cred->euid, pcred->uid) ||
1519 uid_eq(cred->uid, pcred->suid) ||
1520 uid_eq(cred->uid, pcred->uid);
1521}
1522
1523/*
1524 * The usb asyncio usage of siginfo is wrong. The glibc support
1525 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1526 * AKA after the generic fields:
1527 * kernel_pid_t si_pid;
1528 * kernel_uid32_t si_uid;
1529 * sigval_t si_value;
1530 *
1531 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1532 * after the generic fields is:
1533 * void __user *si_addr;
1534 *
1535 * This is a practical problem when there is a 64bit big endian kernel
1536 * and a 32bit userspace. As the 32bit address will encoded in the low
1537 * 32bits of the pointer. Those low 32bits will be stored at higher
1538 * address than appear in a 32 bit pointer. So userspace will not
1539 * see the address it was expecting for it's completions.
1540 *
1541 * There is nothing in the encoding that can allow
1542 * copy_siginfo_to_user32 to detect this confusion of formats, so
1543 * handle this by requiring the caller of kill_pid_usb_asyncio to
1544 * notice when this situration takes place and to store the 32bit
1545 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1546 * parameter.
1547 */
1548int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1549 struct pid *pid, const struct cred *cred)
1550{
1551 struct kernel_siginfo info;
1552 struct task_struct *p;
1553 unsigned long flags;
1554 int ret = -EINVAL;
1555
1556 if (!valid_signal(sig))
1557 return ret;
1558
1559 clear_siginfo(&info);
1560 info.si_signo = sig;
1561 info.si_errno = errno;
1562 info.si_code = SI_ASYNCIO;
1563 *((sigval_t *)&info.si_pid) = addr;
1564
1565 rcu_read_lock();
1566 p = pid_task(pid, PIDTYPE_PID);
1567 if (!p) {
1568 ret = -ESRCH;
1569 goto out_unlock;
1570 }
1571 if (!kill_as_cred_perm(cred, p)) {
1572 ret = -EPERM;
1573 goto out_unlock;
1574 }
1575 ret = security_task_kill(p, &info, sig, cred);
1576 if (ret)
1577 goto out_unlock;
1578
1579 if (sig) {
1580 if (lock_task_sighand(p, &flags)) {
1581 ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false);
1582 unlock_task_sighand(p, &flags);
1583 } else
1584 ret = -ESRCH;
1585 }
1586out_unlock:
1587 rcu_read_unlock();
1588 return ret;
1589}
1590EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1591
1592/*
1593 * kill_something_info() interprets pid in interesting ways just like kill(2).
1594 *
1595 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1596 * is probably wrong. Should make it like BSD or SYSV.
1597 */
1598
1599static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1600{
1601 int ret;
1602
1603 if (pid > 0)
1604 return kill_proc_info(sig, info, pid);
1605
1606 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1607 if (pid == INT_MIN)
1608 return -ESRCH;
1609
1610 read_lock(&tasklist_lock);
1611 if (pid != -1) {
1612 ret = __kill_pgrp_info(sig, info,
1613 pid ? find_vpid(-pid) : task_pgrp(current));
1614 } else {
1615 int retval = 0, count = 0;
1616 struct task_struct * p;
1617
1618 for_each_process(p) {
1619 if (task_pid_vnr(p) > 1 &&
1620 !same_thread_group(p, current)) {
1621 int err = group_send_sig_info(sig, info, p,
1622 PIDTYPE_MAX);
1623 ++count;
1624 if (err != -EPERM)
1625 retval = err;
1626 }
1627 }
1628 ret = count ? retval : -ESRCH;
1629 }
1630 read_unlock(&tasklist_lock);
1631
1632 return ret;
1633}
1634
1635/*
1636 * These are for backward compatibility with the rest of the kernel source.
1637 */
1638
1639int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1640{
1641 /*
1642 * Make sure legacy kernel users don't send in bad values
1643 * (normal paths check this in check_kill_permission).
1644 */
1645 if (!valid_signal(sig))
1646 return -EINVAL;
1647
1648 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1649}
1650EXPORT_SYMBOL(send_sig_info);
1651
1652#define __si_special(priv) \
1653 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1654
1655int
1656send_sig(int sig, struct task_struct *p, int priv)
1657{
1658 return send_sig_info(sig, __si_special(priv), p);
1659}
1660EXPORT_SYMBOL(send_sig);
1661
1662void force_sig(int sig)
1663{
1664 struct kernel_siginfo info;
1665
1666 clear_siginfo(&info);
1667 info.si_signo = sig;
1668 info.si_errno = 0;
1669 info.si_code = SI_KERNEL;
1670 info.si_pid = 0;
1671 info.si_uid = 0;
1672 force_sig_info(&info);
1673}
1674EXPORT_SYMBOL(force_sig);
1675
1676void force_fatal_sig(int sig)
1677{
1678 struct kernel_siginfo info;
1679
1680 clear_siginfo(&info);
1681 info.si_signo = sig;
1682 info.si_errno = 0;
1683 info.si_code = SI_KERNEL;
1684 info.si_pid = 0;
1685 info.si_uid = 0;
1686 force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
1687}
1688
1689void force_exit_sig(int sig)
1690{
1691 struct kernel_siginfo info;
1692
1693 clear_siginfo(&info);
1694 info.si_signo = sig;
1695 info.si_errno = 0;
1696 info.si_code = SI_KERNEL;
1697 info.si_pid = 0;
1698 info.si_uid = 0;
1699 force_sig_info_to_task(&info, current, HANDLER_EXIT);
1700}
1701
1702/*
1703 * When things go south during signal handling, we
1704 * will force a SIGSEGV. And if the signal that caused
1705 * the problem was already a SIGSEGV, we'll want to
1706 * make sure we don't even try to deliver the signal..
1707 */
1708void force_sigsegv(int sig)
1709{
1710 if (sig == SIGSEGV)
1711 force_fatal_sig(SIGSEGV);
1712 else
1713 force_sig(SIGSEGV);
1714}
1715
1716int force_sig_fault_to_task(int sig, int code, void __user *addr,
1717 struct task_struct *t)
1718{
1719 struct kernel_siginfo info;
1720
1721 clear_siginfo(&info);
1722 info.si_signo = sig;
1723 info.si_errno = 0;
1724 info.si_code = code;
1725 info.si_addr = addr;
1726 return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
1727}
1728
1729int force_sig_fault(int sig, int code, void __user *addr)
1730{
1731 return force_sig_fault_to_task(sig, code, addr, current);
1732}
1733
1734int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t)
1735{
1736 struct kernel_siginfo info;
1737
1738 clear_siginfo(&info);
1739 info.si_signo = sig;
1740 info.si_errno = 0;
1741 info.si_code = code;
1742 info.si_addr = addr;
1743 return send_sig_info(info.si_signo, &info, t);
1744}
1745
1746int force_sig_mceerr(int code, void __user *addr, short lsb)
1747{
1748 struct kernel_siginfo info;
1749
1750 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1751 clear_siginfo(&info);
1752 info.si_signo = SIGBUS;
1753 info.si_errno = 0;
1754 info.si_code = code;
1755 info.si_addr = addr;
1756 info.si_addr_lsb = lsb;
1757 return force_sig_info(&info);
1758}
1759
1760int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1761{
1762 struct kernel_siginfo info;
1763
1764 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1765 clear_siginfo(&info);
1766 info.si_signo = SIGBUS;
1767 info.si_errno = 0;
1768 info.si_code = code;
1769 info.si_addr = addr;
1770 info.si_addr_lsb = lsb;
1771 return send_sig_info(info.si_signo, &info, t);
1772}
1773EXPORT_SYMBOL(send_sig_mceerr);
1774
1775int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1776{
1777 struct kernel_siginfo info;
1778
1779 clear_siginfo(&info);
1780 info.si_signo = SIGSEGV;
1781 info.si_errno = 0;
1782 info.si_code = SEGV_BNDERR;
1783 info.si_addr = addr;
1784 info.si_lower = lower;
1785 info.si_upper = upper;
1786 return force_sig_info(&info);
1787}
1788
1789#ifdef SEGV_PKUERR
1790int force_sig_pkuerr(void __user *addr, u32 pkey)
1791{
1792 struct kernel_siginfo info;
1793
1794 clear_siginfo(&info);
1795 info.si_signo = SIGSEGV;
1796 info.si_errno = 0;
1797 info.si_code = SEGV_PKUERR;
1798 info.si_addr = addr;
1799 info.si_pkey = pkey;
1800 return force_sig_info(&info);
1801}
1802#endif
1803
1804int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1805{
1806 struct kernel_siginfo info;
1807
1808 clear_siginfo(&info);
1809 info.si_signo = SIGTRAP;
1810 info.si_errno = 0;
1811 info.si_code = TRAP_PERF;
1812 info.si_addr = addr;
1813 info.si_perf_data = sig_data;
1814 info.si_perf_type = type;
1815
1816 /*
1817 * Signals generated by perf events should not terminate the whole
1818 * process if SIGTRAP is blocked, however, delivering the signal
1819 * asynchronously is better than not delivering at all. But tell user
1820 * space if the signal was asynchronous, so it can clearly be
1821 * distinguished from normal synchronous ones.
1822 */
1823 info.si_perf_flags = sigismember(¤t->blocked, info.si_signo) ?
1824 TRAP_PERF_FLAG_ASYNC :
1825 0;
1826
1827 return send_sig_info(info.si_signo, &info, current);
1828}
1829
1830/**
1831 * force_sig_seccomp - signals the task to allow in-process syscall emulation
1832 * @syscall: syscall number to send to userland
1833 * @reason: filter-supplied reason code to send to userland (via si_errno)
1834 * @force_coredump: true to trigger a coredump
1835 *
1836 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1837 */
1838int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1839{
1840 struct kernel_siginfo info;
1841
1842 clear_siginfo(&info);
1843 info.si_signo = SIGSYS;
1844 info.si_code = SYS_SECCOMP;
1845 info.si_call_addr = (void __user *)KSTK_EIP(current);
1846 info.si_errno = reason;
1847 info.si_arch = syscall_get_arch(current);
1848 info.si_syscall = syscall;
1849 return force_sig_info_to_task(&info, current,
1850 force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1851}
1852
1853/* For the crazy architectures that include trap information in
1854 * the errno field, instead of an actual errno value.
1855 */
1856int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1857{
1858 struct kernel_siginfo info;
1859
1860 clear_siginfo(&info);
1861 info.si_signo = SIGTRAP;
1862 info.si_errno = errno;
1863 info.si_code = TRAP_HWBKPT;
1864 info.si_addr = addr;
1865 return force_sig_info(&info);
1866}
1867
1868/* For the rare architectures that include trap information using
1869 * si_trapno.
1870 */
1871int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1872{
1873 struct kernel_siginfo info;
1874
1875 clear_siginfo(&info);
1876 info.si_signo = sig;
1877 info.si_errno = 0;
1878 info.si_code = code;
1879 info.si_addr = addr;
1880 info.si_trapno = trapno;
1881 return force_sig_info(&info);
1882}
1883
1884/* For the rare architectures that include trap information using
1885 * si_trapno.
1886 */
1887int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1888 struct task_struct *t)
1889{
1890 struct kernel_siginfo info;
1891
1892 clear_siginfo(&info);
1893 info.si_signo = sig;
1894 info.si_errno = 0;
1895 info.si_code = code;
1896 info.si_addr = addr;
1897 info.si_trapno = trapno;
1898 return send_sig_info(info.si_signo, &info, t);
1899}
1900
1901int kill_pgrp(struct pid *pid, int sig, int priv)
1902{
1903 int ret;
1904
1905 read_lock(&tasklist_lock);
1906 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1907 read_unlock(&tasklist_lock);
1908
1909 return ret;
1910}
1911EXPORT_SYMBOL(kill_pgrp);
1912
1913int kill_pid(struct pid *pid, int sig, int priv)
1914{
1915 return kill_pid_info(sig, __si_special(priv), pid);
1916}
1917EXPORT_SYMBOL(kill_pid);
1918
1919/*
1920 * These functions support sending signals using preallocated sigqueue
1921 * structures. This is needed "because realtime applications cannot
1922 * afford to lose notifications of asynchronous events, like timer
1923 * expirations or I/O completions". In the case of POSIX Timers
1924 * we allocate the sigqueue structure from the timer_create. If this
1925 * allocation fails we are able to report the failure to the application
1926 * with an EAGAIN error.
1927 */
1928struct sigqueue *sigqueue_alloc(void)
1929{
1930 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1931}
1932
1933void sigqueue_free(struct sigqueue *q)
1934{
1935 unsigned long flags;
1936 spinlock_t *lock = ¤t->sighand->siglock;
1937
1938 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1939 /*
1940 * We must hold ->siglock while testing q->list
1941 * to serialize with collect_signal() or with
1942 * __exit_signal()->flush_sigqueue().
1943 */
1944 spin_lock_irqsave(lock, flags);
1945 q->flags &= ~SIGQUEUE_PREALLOC;
1946 /*
1947 * If it is queued it will be freed when dequeued,
1948 * like the "regular" sigqueue.
1949 */
1950 if (!list_empty(&q->list))
1951 q = NULL;
1952 spin_unlock_irqrestore(lock, flags);
1953
1954 if (q)
1955 __sigqueue_free(q);
1956}
1957
1958int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1959{
1960 int sig = q->info.si_signo;
1961 struct sigpending *pending;
1962 struct task_struct *t;
1963 unsigned long flags;
1964 int ret, result;
1965
1966 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1967
1968 ret = -1;
1969 rcu_read_lock();
1970
1971 /*
1972 * This function is used by POSIX timers to deliver a timer signal.
1973 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1974 * set), the signal must be delivered to the specific thread (queues
1975 * into t->pending).
1976 *
1977 * Where type is not PIDTYPE_PID, signals must be delivered to the
1978 * process. In this case, prefer to deliver to current if it is in
1979 * the same thread group as the target process, which avoids
1980 * unnecessarily waking up a potentially idle task.
1981 */
1982 t = pid_task(pid, type);
1983 if (!t)
1984 goto ret;
1985 if (type != PIDTYPE_PID && same_thread_group(t, current))
1986 t = current;
1987 if (!likely(lock_task_sighand(t, &flags)))
1988 goto ret;
1989
1990 ret = 1; /* the signal is ignored */
1991 result = TRACE_SIGNAL_IGNORED;
1992 if (!prepare_signal(sig, t, false))
1993 goto out;
1994
1995 ret = 0;
1996 if (unlikely(!list_empty(&q->list))) {
1997 /*
1998 * If an SI_TIMER entry is already queue just increment
1999 * the overrun count.
2000 */
2001 BUG_ON(q->info.si_code != SI_TIMER);
2002 q->info.si_overrun++;
2003 result = TRACE_SIGNAL_ALREADY_PENDING;
2004 goto out;
2005 }
2006 q->info.si_overrun = 0;
2007
2008 signalfd_notify(t, sig);
2009 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
2010 list_add_tail(&q->list, &pending->list);
2011 sigaddset(&pending->signal, sig);
2012 complete_signal(sig, t, type);
2013 result = TRACE_SIGNAL_DELIVERED;
2014out:
2015 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
2016 unlock_task_sighand(t, &flags);
2017ret:
2018 rcu_read_unlock();
2019 return ret;
2020}
2021
2022static void do_notify_pidfd(struct task_struct *task)
2023{
2024 struct pid *pid;
2025
2026 WARN_ON(task->exit_state == 0);
2027 pid = task_pid(task);
2028 wake_up_all(&pid->wait_pidfd);
2029}
2030
2031/*
2032 * Let a parent know about the death of a child.
2033 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2034 *
2035 * Returns true if our parent ignored us and so we've switched to
2036 * self-reaping.
2037 */
2038bool do_notify_parent(struct task_struct *tsk, int sig)
2039{
2040 struct kernel_siginfo info;
2041 unsigned long flags;
2042 struct sighand_struct *psig;
2043 bool autoreap = false;
2044 u64 utime, stime;
2045
2046 WARN_ON_ONCE(sig == -1);
2047
2048 /* do_notify_parent_cldstop should have been called instead. */
2049 WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2050
2051 WARN_ON_ONCE(!tsk->ptrace &&
2052 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2053
2054 /* Wake up all pidfd waiters */
2055 do_notify_pidfd(tsk);
2056
2057 if (sig != SIGCHLD) {
2058 /*
2059 * This is only possible if parent == real_parent.
2060 * Check if it has changed security domain.
2061 */
2062 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2063 sig = SIGCHLD;
2064 }
2065
2066 clear_siginfo(&info);
2067 info.si_signo = sig;
2068 info.si_errno = 0;
2069 /*
2070 * We are under tasklist_lock here so our parent is tied to
2071 * us and cannot change.
2072 *
2073 * task_active_pid_ns will always return the same pid namespace
2074 * until a task passes through release_task.
2075 *
2076 * write_lock() currently calls preempt_disable() which is the
2077 * same as rcu_read_lock(), but according to Oleg, this is not
2078 * correct to rely on this
2079 */
2080 rcu_read_lock();
2081 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2082 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2083 task_uid(tsk));
2084 rcu_read_unlock();
2085
2086 task_cputime(tsk, &utime, &stime);
2087 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2088 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2089
2090 info.si_status = tsk->exit_code & 0x7f;
2091 if (tsk->exit_code & 0x80)
2092 info.si_code = CLD_DUMPED;
2093 else if (tsk->exit_code & 0x7f)
2094 info.si_code = CLD_KILLED;
2095 else {
2096 info.si_code = CLD_EXITED;
2097 info.si_status = tsk->exit_code >> 8;
2098 }
2099
2100 psig = tsk->parent->sighand;
2101 spin_lock_irqsave(&psig->siglock, flags);
2102 if (!tsk->ptrace && sig == SIGCHLD &&
2103 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2104 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2105 /*
2106 * We are exiting and our parent doesn't care. POSIX.1
2107 * defines special semantics for setting SIGCHLD to SIG_IGN
2108 * or setting the SA_NOCLDWAIT flag: we should be reaped
2109 * automatically and not left for our parent's wait4 call.
2110 * Rather than having the parent do it as a magic kind of
2111 * signal handler, we just set this to tell do_exit that we
2112 * can be cleaned up without becoming a zombie. Note that
2113 * we still call __wake_up_parent in this case, because a
2114 * blocked sys_wait4 might now return -ECHILD.
2115 *
2116 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2117 * is implementation-defined: we do (if you don't want
2118 * it, just use SIG_IGN instead).
2119 */
2120 autoreap = true;
2121 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2122 sig = 0;
2123 }
2124 /*
2125 * Send with __send_signal as si_pid and si_uid are in the
2126 * parent's namespaces.
2127 */
2128 if (valid_signal(sig) && sig)
2129 __send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2130 __wake_up_parent(tsk, tsk->parent);
2131 spin_unlock_irqrestore(&psig->siglock, flags);
2132
2133 return autoreap;
2134}
2135
2136/**
2137 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2138 * @tsk: task reporting the state change
2139 * @for_ptracer: the notification is for ptracer
2140 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2141 *
2142 * Notify @tsk's parent that the stopped/continued state has changed. If
2143 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2144 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2145 *
2146 * CONTEXT:
2147 * Must be called with tasklist_lock at least read locked.
2148 */
2149static void do_notify_parent_cldstop(struct task_struct *tsk,
2150 bool for_ptracer, int why)
2151{
2152 struct kernel_siginfo info;
2153 unsigned long flags;
2154 struct task_struct *parent;
2155 struct sighand_struct *sighand;
2156 u64 utime, stime;
2157
2158 if (for_ptracer) {
2159 parent = tsk->parent;
2160 } else {
2161 tsk = tsk->group_leader;
2162 parent = tsk->real_parent;
2163 }
2164
2165 clear_siginfo(&info);
2166 info.si_signo = SIGCHLD;
2167 info.si_errno = 0;
2168 /*
2169 * see comment in do_notify_parent() about the following 4 lines
2170 */
2171 rcu_read_lock();
2172 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2173 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2174 rcu_read_unlock();
2175
2176 task_cputime(tsk, &utime, &stime);
2177 info.si_utime = nsec_to_clock_t(utime);
2178 info.si_stime = nsec_to_clock_t(stime);
2179
2180 info.si_code = why;
2181 switch (why) {
2182 case CLD_CONTINUED:
2183 info.si_status = SIGCONT;
2184 break;
2185 case CLD_STOPPED:
2186 info.si_status = tsk->signal->group_exit_code & 0x7f;
2187 break;
2188 case CLD_TRAPPED:
2189 info.si_status = tsk->exit_code & 0x7f;
2190 break;
2191 default:
2192 BUG();
2193 }
2194
2195 sighand = parent->sighand;
2196 spin_lock_irqsave(&sighand->siglock, flags);
2197 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2198 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2199 send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID);
2200 /*
2201 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2202 */
2203 __wake_up_parent(tsk, parent);
2204 spin_unlock_irqrestore(&sighand->siglock, flags);
2205}
2206
2207/*
2208 * This must be called with current->sighand->siglock held.
2209 *
2210 * This should be the path for all ptrace stops.
2211 * We always set current->last_siginfo while stopped here.
2212 * That makes it a way to test a stopped process for
2213 * being ptrace-stopped vs being job-control-stopped.
2214 *
2215 * Returns the signal the ptracer requested the code resume
2216 * with. If the code did not stop because the tracer is gone,
2217 * the stop signal remains unchanged unless clear_code.
2218 */
2219static int ptrace_stop(int exit_code, int why, unsigned long message,
2220 kernel_siginfo_t *info)
2221 __releases(¤t->sighand->siglock)
2222 __acquires(¤t->sighand->siglock)
2223{
2224 bool gstop_done = false;
2225
2226 if (arch_ptrace_stop_needed()) {
2227 /*
2228 * The arch code has something special to do before a
2229 * ptrace stop. This is allowed to block, e.g. for faults
2230 * on user stack pages. We can't keep the siglock while
2231 * calling arch_ptrace_stop, so we must release it now.
2232 * To preserve proper semantics, we must do this before
2233 * any signal bookkeeping like checking group_stop_count.
2234 */
2235 spin_unlock_irq(¤t->sighand->siglock);
2236 arch_ptrace_stop();
2237 spin_lock_irq(¤t->sighand->siglock);
2238 }
2239
2240 /*
2241 * After this point ptrace_signal_wake_up or signal_wake_up
2242 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
2243 * signal comes in. Handle previous ptrace_unlinks and fatal
2244 * signals here to prevent ptrace_stop sleeping in schedule.
2245 */
2246 if (!current->ptrace || __fatal_signal_pending(current))
2247 return exit_code;
2248
2249 set_special_state(TASK_TRACED);
2250 current->jobctl |= JOBCTL_TRACED;
2251
2252 /*
2253 * We're committing to trapping. TRACED should be visible before
2254 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2255 * Also, transition to TRACED and updates to ->jobctl should be
2256 * atomic with respect to siglock and should be done after the arch
2257 * hook as siglock is released and regrabbed across it.
2258 *
2259 * TRACER TRACEE
2260 *
2261 * ptrace_attach()
2262 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2263 * do_wait()
2264 * set_current_state() smp_wmb();
2265 * ptrace_do_wait()
2266 * wait_task_stopped()
2267 * task_stopped_code()
2268 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2269 */
2270 smp_wmb();
2271
2272 current->ptrace_message = message;
2273 current->last_siginfo = info;
2274 current->exit_code = exit_code;
2275
2276 /*
2277 * If @why is CLD_STOPPED, we're trapping to participate in a group
2278 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2279 * across siglock relocks since INTERRUPT was scheduled, PENDING
2280 * could be clear now. We act as if SIGCONT is received after
2281 * TASK_TRACED is entered - ignore it.
2282 */
2283 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2284 gstop_done = task_participate_group_stop(current);
2285
2286 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2287 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2288 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2289 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2290
2291 /* entering a trap, clear TRAPPING */
2292 task_clear_jobctl_trapping(current);
2293
2294 spin_unlock_irq(¤t->sighand->siglock);
2295 read_lock(&tasklist_lock);
2296 /*
2297 * Notify parents of the stop.
2298 *
2299 * While ptraced, there are two parents - the ptracer and
2300 * the real_parent of the group_leader. The ptracer should
2301 * know about every stop while the real parent is only
2302 * interested in the completion of group stop. The states
2303 * for the two don't interact with each other. Notify
2304 * separately unless they're gonna be duplicates.
2305 */
2306 if (current->ptrace)
2307 do_notify_parent_cldstop(current, true, why);
2308 if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2309 do_notify_parent_cldstop(current, false, why);
2310
2311 /*
2312 * The previous do_notify_parent_cldstop() invocation woke ptracer.
2313 * One a PREEMPTION kernel this can result in preemption requirement
2314 * which will be fulfilled after read_unlock() and the ptracer will be
2315 * put on the CPU.
2316 * The ptracer is in wait_task_inactive(, __TASK_TRACED) waiting for
2317 * this task wait in schedule(). If this task gets preempted then it
2318 * remains enqueued on the runqueue. The ptracer will observe this and
2319 * then sleep for a delay of one HZ tick. In the meantime this task
2320 * gets scheduled, enters schedule() and will wait for the ptracer.
2321 *
2322 * This preemption point is not bad from a correctness point of
2323 * view but extends the runtime by one HZ tick time due to the
2324 * ptracer's sleep. The preempt-disable section ensures that there
2325 * will be no preemption between unlock and schedule() and so
2326 * improving the performance since the ptracer will observe that
2327 * the tracee is scheduled out once it gets on the CPU.
2328 *
2329 * On PREEMPT_RT locking tasklist_lock does not disable preemption.
2330 * Therefore the task can be preempted after do_notify_parent_cldstop()
2331 * before unlocking tasklist_lock so there is no benefit in doing this.
2332 *
2333 * In fact disabling preemption is harmful on PREEMPT_RT because
2334 * the spinlock_t in cgroup_enter_frozen() must not be acquired
2335 * with preemption disabled due to the 'sleeping' spinlock
2336 * substitution of RT.
2337 */
2338 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2339 preempt_disable();
2340 read_unlock(&tasklist_lock);
2341 cgroup_enter_frozen();
2342 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2343 preempt_enable_no_resched();
2344 schedule();
2345 cgroup_leave_frozen(true);
2346
2347 /*
2348 * We are back. Now reacquire the siglock before touching
2349 * last_siginfo, so that we are sure to have synchronized with
2350 * any signal-sending on another CPU that wants to examine it.
2351 */
2352 spin_lock_irq(¤t->sighand->siglock);
2353 exit_code = current->exit_code;
2354 current->last_siginfo = NULL;
2355 current->ptrace_message = 0;
2356 current->exit_code = 0;
2357
2358 /* LISTENING can be set only during STOP traps, clear it */
2359 current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2360
2361 /*
2362 * Queued signals ignored us while we were stopped for tracing.
2363 * So check for any that we should take before resuming user mode.
2364 * This sets TIF_SIGPENDING, but never clears it.
2365 */
2366 recalc_sigpending_tsk(current);
2367 return exit_code;
2368}
2369
2370static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2371{
2372 kernel_siginfo_t info;
2373
2374 clear_siginfo(&info);
2375 info.si_signo = signr;
2376 info.si_code = exit_code;
2377 info.si_pid = task_pid_vnr(current);
2378 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2379
2380 /* Let the debugger run. */
2381 return ptrace_stop(exit_code, why, message, &info);
2382}
2383
2384int ptrace_notify(int exit_code, unsigned long message)
2385{
2386 int signr;
2387
2388 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2389 if (unlikely(task_work_pending(current)))
2390 task_work_run();
2391
2392 spin_lock_irq(¤t->sighand->siglock);
2393 signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2394 spin_unlock_irq(¤t->sighand->siglock);
2395 return signr;
2396}
2397
2398/**
2399 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2400 * @signr: signr causing group stop if initiating
2401 *
2402 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2403 * and participate in it. If already set, participate in the existing
2404 * group stop. If participated in a group stop (and thus slept), %true is
2405 * returned with siglock released.
2406 *
2407 * If ptraced, this function doesn't handle stop itself. Instead,
2408 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2409 * untouched. The caller must ensure that INTERRUPT trap handling takes
2410 * places afterwards.
2411 *
2412 * CONTEXT:
2413 * Must be called with @current->sighand->siglock held, which is released
2414 * on %true return.
2415 *
2416 * RETURNS:
2417 * %false if group stop is already cancelled or ptrace trap is scheduled.
2418 * %true if participated in group stop.
2419 */
2420static bool do_signal_stop(int signr)
2421 __releases(¤t->sighand->siglock)
2422{
2423 struct signal_struct *sig = current->signal;
2424
2425 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2426 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2427 struct task_struct *t;
2428
2429 /* signr will be recorded in task->jobctl for retries */
2430 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2431
2432 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2433 unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2434 unlikely(sig->group_exec_task))
2435 return false;
2436 /*
2437 * There is no group stop already in progress. We must
2438 * initiate one now.
2439 *
2440 * While ptraced, a task may be resumed while group stop is
2441 * still in effect and then receive a stop signal and
2442 * initiate another group stop. This deviates from the
2443 * usual behavior as two consecutive stop signals can't
2444 * cause two group stops when !ptraced. That is why we
2445 * also check !task_is_stopped(t) below.
2446 *
2447 * The condition can be distinguished by testing whether
2448 * SIGNAL_STOP_STOPPED is already set. Don't generate
2449 * group_exit_code in such case.
2450 *
2451 * This is not necessary for SIGNAL_STOP_CONTINUED because
2452 * an intervening stop signal is required to cause two
2453 * continued events regardless of ptrace.
2454 */
2455 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2456 sig->group_exit_code = signr;
2457
2458 sig->group_stop_count = 0;
2459 if (task_set_jobctl_pending(current, signr | gstop))
2460 sig->group_stop_count++;
2461
2462 for_other_threads(current, t) {
2463 /*
2464 * Setting state to TASK_STOPPED for a group
2465 * stop is always done with the siglock held,
2466 * so this check has no races.
2467 */
2468 if (!task_is_stopped(t) &&
2469 task_set_jobctl_pending(t, signr | gstop)) {
2470 sig->group_stop_count++;
2471 if (likely(!(t->ptrace & PT_SEIZED)))
2472 signal_wake_up(t, 0);
2473 else
2474 ptrace_trap_notify(t);
2475 }
2476 }
2477 }
2478
2479 if (likely(!current->ptrace)) {
2480 int notify = 0;
2481
2482 /*
2483 * If there are no other threads in the group, or if there
2484 * is a group stop in progress and we are the last to stop,
2485 * report to the parent.
2486 */
2487 if (task_participate_group_stop(current))
2488 notify = CLD_STOPPED;
2489
2490 current->jobctl |= JOBCTL_STOPPED;
2491 set_special_state(TASK_STOPPED);
2492 spin_unlock_irq(¤t->sighand->siglock);
2493
2494 /*
2495 * Notify the parent of the group stop completion. Because
2496 * we're not holding either the siglock or tasklist_lock
2497 * here, ptracer may attach inbetween; however, this is for
2498 * group stop and should always be delivered to the real
2499 * parent of the group leader. The new ptracer will get
2500 * its notification when this task transitions into
2501 * TASK_TRACED.
2502 */
2503 if (notify) {
2504 read_lock(&tasklist_lock);
2505 do_notify_parent_cldstop(current, false, notify);
2506 read_unlock(&tasklist_lock);
2507 }
2508
2509 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2510 cgroup_enter_frozen();
2511 schedule();
2512 return true;
2513 } else {
2514 /*
2515 * While ptraced, group stop is handled by STOP trap.
2516 * Schedule it and let the caller deal with it.
2517 */
2518 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2519 return false;
2520 }
2521}
2522
2523/**
2524 * do_jobctl_trap - take care of ptrace jobctl traps
2525 *
2526 * When PT_SEIZED, it's used for both group stop and explicit
2527 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2528 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2529 * the stop signal; otherwise, %SIGTRAP.
2530 *
2531 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2532 * number as exit_code and no siginfo.
2533 *
2534 * CONTEXT:
2535 * Must be called with @current->sighand->siglock held, which may be
2536 * released and re-acquired before returning with intervening sleep.
2537 */
2538static void do_jobctl_trap(void)
2539{
2540 struct signal_struct *signal = current->signal;
2541 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2542
2543 if (current->ptrace & PT_SEIZED) {
2544 if (!signal->group_stop_count &&
2545 !(signal->flags & SIGNAL_STOP_STOPPED))
2546 signr = SIGTRAP;
2547 WARN_ON_ONCE(!signr);
2548 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2549 CLD_STOPPED, 0);
2550 } else {
2551 WARN_ON_ONCE(!signr);
2552 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2553 }
2554}
2555
2556/**
2557 * do_freezer_trap - handle the freezer jobctl trap
2558 *
2559 * Puts the task into frozen state, if only the task is not about to quit.
2560 * In this case it drops JOBCTL_TRAP_FREEZE.
2561 *
2562 * CONTEXT:
2563 * Must be called with @current->sighand->siglock held,
2564 * which is always released before returning.
2565 */
2566static void do_freezer_trap(void)
2567 __releases(¤t->sighand->siglock)
2568{
2569 /*
2570 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2571 * let's make another loop to give it a chance to be handled.
2572 * In any case, we'll return back.
2573 */
2574 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2575 JOBCTL_TRAP_FREEZE) {
2576 spin_unlock_irq(¤t->sighand->siglock);
2577 return;
2578 }
2579
2580 /*
2581 * Now we're sure that there is no pending fatal signal and no
2582 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2583 * immediately (if there is a non-fatal signal pending), and
2584 * put the task into sleep.
2585 */
2586 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2587 clear_thread_flag(TIF_SIGPENDING);
2588 spin_unlock_irq(¤t->sighand->siglock);
2589 cgroup_enter_frozen();
2590 schedule();
2591}
2592
2593static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2594{
2595 /*
2596 * We do not check sig_kernel_stop(signr) but set this marker
2597 * unconditionally because we do not know whether debugger will
2598 * change signr. This flag has no meaning unless we are going
2599 * to stop after return from ptrace_stop(). In this case it will
2600 * be checked in do_signal_stop(), we should only stop if it was
2601 * not cleared by SIGCONT while we were sleeping. See also the
2602 * comment in dequeue_signal().
2603 */
2604 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2605 signr = ptrace_stop(signr, CLD_TRAPPED, 0, info);
2606
2607 /* We're back. Did the debugger cancel the sig? */
2608 if (signr == 0)
2609 return signr;
2610
2611 /*
2612 * Update the siginfo structure if the signal has
2613 * changed. If the debugger wanted something
2614 * specific in the siginfo structure then it should
2615 * have updated *info via PTRACE_SETSIGINFO.
2616 */
2617 if (signr != info->si_signo) {
2618 clear_siginfo(info);
2619 info->si_signo = signr;
2620 info->si_errno = 0;
2621 info->si_code = SI_USER;
2622 rcu_read_lock();
2623 info->si_pid = task_pid_vnr(current->parent);
2624 info->si_uid = from_kuid_munged(current_user_ns(),
2625 task_uid(current->parent));
2626 rcu_read_unlock();
2627 }
2628
2629 /* If the (new) signal is now blocked, requeue it. */
2630 if (sigismember(¤t->blocked, signr) ||
2631 fatal_signal_pending(current)) {
2632 send_signal_locked(signr, info, current, type);
2633 signr = 0;
2634 }
2635
2636 return signr;
2637}
2638
2639static void hide_si_addr_tag_bits(struct ksignal *ksig)
2640{
2641 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2642 case SIL_FAULT:
2643 case SIL_FAULT_TRAPNO:
2644 case SIL_FAULT_MCEERR:
2645 case SIL_FAULT_BNDERR:
2646 case SIL_FAULT_PKUERR:
2647 case SIL_FAULT_PERF_EVENT:
2648 ksig->info.si_addr = arch_untagged_si_addr(
2649 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2650 break;
2651 case SIL_KILL:
2652 case SIL_TIMER:
2653 case SIL_POLL:
2654 case SIL_CHLD:
2655 case SIL_RT:
2656 case SIL_SYS:
2657 break;
2658 }
2659}
2660
2661bool get_signal(struct ksignal *ksig)
2662{
2663 struct sighand_struct *sighand = current->sighand;
2664 struct signal_struct *signal = current->signal;
2665 int signr;
2666
2667 clear_notify_signal();
2668 if (unlikely(task_work_pending(current)))
2669 task_work_run();
2670
2671 if (!task_sigpending(current))
2672 return false;
2673
2674 if (unlikely(uprobe_deny_signal()))
2675 return false;
2676
2677 /*
2678 * Do this once, we can't return to user-mode if freezing() == T.
2679 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2680 * thus do not need another check after return.
2681 */
2682 try_to_freeze();
2683
2684relock:
2685 spin_lock_irq(&sighand->siglock);
2686
2687 /*
2688 * Every stopped thread goes here after wakeup. Check to see if
2689 * we should notify the parent, prepare_signal(SIGCONT) encodes
2690 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2691 */
2692 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2693 int why;
2694
2695 if (signal->flags & SIGNAL_CLD_CONTINUED)
2696 why = CLD_CONTINUED;
2697 else
2698 why = CLD_STOPPED;
2699
2700 signal->flags &= ~SIGNAL_CLD_MASK;
2701
2702 spin_unlock_irq(&sighand->siglock);
2703
2704 /*
2705 * Notify the parent that we're continuing. This event is
2706 * always per-process and doesn't make whole lot of sense
2707 * for ptracers, who shouldn't consume the state via
2708 * wait(2) either, but, for backward compatibility, notify
2709 * the ptracer of the group leader too unless it's gonna be
2710 * a duplicate.
2711 */
2712 read_lock(&tasklist_lock);
2713 do_notify_parent_cldstop(current, false, why);
2714
2715 if (ptrace_reparented(current->group_leader))
2716 do_notify_parent_cldstop(current->group_leader,
2717 true, why);
2718 read_unlock(&tasklist_lock);
2719
2720 goto relock;
2721 }
2722
2723 for (;;) {
2724 struct k_sigaction *ka;
2725 enum pid_type type;
2726
2727 /* Has this task already been marked for death? */
2728 if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2729 signal->group_exec_task) {
2730 clear_siginfo(&ksig->info);
2731 ksig->info.si_signo = signr = SIGKILL;
2732 sigdelset(¤t->pending.signal, SIGKILL);
2733 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2734 &sighand->action[SIGKILL - 1]);
2735 recalc_sigpending();
2736 goto fatal;
2737 }
2738
2739 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2740 do_signal_stop(0))
2741 goto relock;
2742
2743 if (unlikely(current->jobctl &
2744 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2745 if (current->jobctl & JOBCTL_TRAP_MASK) {
2746 do_jobctl_trap();
2747 spin_unlock_irq(&sighand->siglock);
2748 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2749 do_freezer_trap();
2750
2751 goto relock;
2752 }
2753
2754 /*
2755 * If the task is leaving the frozen state, let's update
2756 * cgroup counters and reset the frozen bit.
2757 */
2758 if (unlikely(cgroup_task_frozen(current))) {
2759 spin_unlock_irq(&sighand->siglock);
2760 cgroup_leave_frozen(false);
2761 goto relock;
2762 }
2763
2764 /*
2765 * Signals generated by the execution of an instruction
2766 * need to be delivered before any other pending signals
2767 * so that the instruction pointer in the signal stack
2768 * frame points to the faulting instruction.
2769 */
2770 type = PIDTYPE_PID;
2771 signr = dequeue_synchronous_signal(&ksig->info);
2772 if (!signr)
2773 signr = dequeue_signal(current, ¤t->blocked,
2774 &ksig->info, &type);
2775
2776 if (!signr)
2777 break; /* will return 0 */
2778
2779 if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2780 !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2781 signr = ptrace_signal(signr, &ksig->info, type);
2782 if (!signr)
2783 continue;
2784 }
2785
2786 ka = &sighand->action[signr-1];
2787
2788 /* Trace actually delivered signals. */
2789 trace_signal_deliver(signr, &ksig->info, ka);
2790
2791 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2792 continue;
2793 if (ka->sa.sa_handler != SIG_DFL) {
2794 /* Run the handler. */
2795 ksig->ka = *ka;
2796
2797 if (ka->sa.sa_flags & SA_ONESHOT)
2798 ka->sa.sa_handler = SIG_DFL;
2799
2800 break; /* will return non-zero "signr" value */
2801 }
2802
2803 /*
2804 * Now we are doing the default action for this signal.
2805 */
2806 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2807 continue;
2808
2809 /*
2810 * Global init gets no signals it doesn't want.
2811 * Container-init gets no signals it doesn't want from same
2812 * container.
2813 *
2814 * Note that if global/container-init sees a sig_kernel_only()
2815 * signal here, the signal must have been generated internally
2816 * or must have come from an ancestor namespace. In either
2817 * case, the signal cannot be dropped.
2818 */
2819 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2820 !sig_kernel_only(signr))
2821 continue;
2822
2823 if (sig_kernel_stop(signr)) {
2824 /*
2825 * The default action is to stop all threads in
2826 * the thread group. The job control signals
2827 * do nothing in an orphaned pgrp, but SIGSTOP
2828 * always works. Note that siglock needs to be
2829 * dropped during the call to is_orphaned_pgrp()
2830 * because of lock ordering with tasklist_lock.
2831 * This allows an intervening SIGCONT to be posted.
2832 * We need to check for that and bail out if necessary.
2833 */
2834 if (signr != SIGSTOP) {
2835 spin_unlock_irq(&sighand->siglock);
2836
2837 /* signals can be posted during this window */
2838
2839 if (is_current_pgrp_orphaned())
2840 goto relock;
2841
2842 spin_lock_irq(&sighand->siglock);
2843 }
2844
2845 if (likely(do_signal_stop(ksig->info.si_signo))) {
2846 /* It released the siglock. */
2847 goto relock;
2848 }
2849
2850 /*
2851 * We didn't actually stop, due to a race
2852 * with SIGCONT or something like that.
2853 */
2854 continue;
2855 }
2856
2857 fatal:
2858 spin_unlock_irq(&sighand->siglock);
2859 if (unlikely(cgroup_task_frozen(current)))
2860 cgroup_leave_frozen(true);
2861
2862 /*
2863 * Anything else is fatal, maybe with a core dump.
2864 */
2865 current->flags |= PF_SIGNALED;
2866
2867 if (sig_kernel_coredump(signr)) {
2868 if (print_fatal_signals)
2869 print_fatal_signal(ksig->info.si_signo);
2870 proc_coredump_connector(current);
2871 /*
2872 * If it was able to dump core, this kills all
2873 * other threads in the group and synchronizes with
2874 * their demise. If we lost the race with another
2875 * thread getting here, it set group_exit_code
2876 * first and our do_group_exit call below will use
2877 * that value and ignore the one we pass it.
2878 */
2879 do_coredump(&ksig->info);
2880 }
2881
2882 /*
2883 * PF_USER_WORKER threads will catch and exit on fatal signals
2884 * themselves. They have cleanup that must be performed, so
2885 * we cannot call do_exit() on their behalf.
2886 */
2887 if (current->flags & PF_USER_WORKER)
2888 goto out;
2889
2890 /*
2891 * Death signals, no core dump.
2892 */
2893 do_group_exit(ksig->info.si_signo);
2894 /* NOTREACHED */
2895 }
2896 spin_unlock_irq(&sighand->siglock);
2897out:
2898 ksig->sig = signr;
2899
2900 if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2901 hide_si_addr_tag_bits(ksig);
2902
2903 return ksig->sig > 0;
2904}
2905
2906/**
2907 * signal_delivered - called after signal delivery to update blocked signals
2908 * @ksig: kernel signal struct
2909 * @stepping: nonzero if debugger single-step or block-step in use
2910 *
2911 * This function should be called when a signal has successfully been
2912 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2913 * is always blocked), and the signal itself is blocked unless %SA_NODEFER
2914 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2915 */
2916static void signal_delivered(struct ksignal *ksig, int stepping)
2917{
2918 sigset_t blocked;
2919
2920 /* A signal was successfully delivered, and the
2921 saved sigmask was stored on the signal frame,
2922 and will be restored by sigreturn. So we can
2923 simply clear the restore sigmask flag. */
2924 clear_restore_sigmask();
2925
2926 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2927 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2928 sigaddset(&blocked, ksig->sig);
2929 set_current_blocked(&blocked);
2930 if (current->sas_ss_flags & SS_AUTODISARM)
2931 sas_ss_reset(current);
2932 if (stepping)
2933 ptrace_notify(SIGTRAP, 0);
2934}
2935
2936void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2937{
2938 if (failed)
2939 force_sigsegv(ksig->sig);
2940 else
2941 signal_delivered(ksig, stepping);
2942}
2943
2944/*
2945 * It could be that complete_signal() picked us to notify about the
2946 * group-wide signal. Other threads should be notified now to take
2947 * the shared signals in @which since we will not.
2948 */
2949static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2950{
2951 sigset_t retarget;
2952 struct task_struct *t;
2953
2954 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2955 if (sigisemptyset(&retarget))
2956 return;
2957
2958 for_other_threads(tsk, t) {
2959 if (t->flags & PF_EXITING)
2960 continue;
2961
2962 if (!has_pending_signals(&retarget, &t->blocked))
2963 continue;
2964 /* Remove the signals this thread can handle. */
2965 sigandsets(&retarget, &retarget, &t->blocked);
2966
2967 if (!task_sigpending(t))
2968 signal_wake_up(t, 0);
2969
2970 if (sigisemptyset(&retarget))
2971 break;
2972 }
2973}
2974
2975void exit_signals(struct task_struct *tsk)
2976{
2977 int group_stop = 0;
2978 sigset_t unblocked;
2979
2980 /*
2981 * @tsk is about to have PF_EXITING set - lock out users which
2982 * expect stable threadgroup.
2983 */
2984 cgroup_threadgroup_change_begin(tsk);
2985
2986 if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
2987 sched_mm_cid_exit_signals(tsk);
2988 tsk->flags |= PF_EXITING;
2989 cgroup_threadgroup_change_end(tsk);
2990 return;
2991 }
2992
2993 spin_lock_irq(&tsk->sighand->siglock);
2994 /*
2995 * From now this task is not visible for group-wide signals,
2996 * see wants_signal(), do_signal_stop().
2997 */
2998 sched_mm_cid_exit_signals(tsk);
2999 tsk->flags |= PF_EXITING;
3000
3001 cgroup_threadgroup_change_end(tsk);
3002
3003 if (!task_sigpending(tsk))
3004 goto out;
3005
3006 unblocked = tsk->blocked;
3007 signotset(&unblocked);
3008 retarget_shared_pending(tsk, &unblocked);
3009
3010 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3011 task_participate_group_stop(tsk))
3012 group_stop = CLD_STOPPED;
3013out:
3014 spin_unlock_irq(&tsk->sighand->siglock);
3015
3016 /*
3017 * If group stop has completed, deliver the notification. This
3018 * should always go to the real parent of the group leader.
3019 */
3020 if (unlikely(group_stop)) {
3021 read_lock(&tasklist_lock);
3022 do_notify_parent_cldstop(tsk, false, group_stop);
3023 read_unlock(&tasklist_lock);
3024 }
3025}
3026
3027/*
3028 * System call entry points.
3029 */
3030
3031/**
3032 * sys_restart_syscall - restart a system call
3033 */
3034SYSCALL_DEFINE0(restart_syscall)
3035{
3036 struct restart_block *restart = ¤t->restart_block;
3037 return restart->fn(restart);
3038}
3039
3040long do_no_restart_syscall(struct restart_block *param)
3041{
3042 return -EINTR;
3043}
3044
3045static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3046{
3047 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
3048 sigset_t newblocked;
3049 /* A set of now blocked but previously unblocked signals. */
3050 sigandnsets(&newblocked, newset, ¤t->blocked);
3051 retarget_shared_pending(tsk, &newblocked);
3052 }
3053 tsk->blocked = *newset;
3054 recalc_sigpending();
3055}
3056
3057/**
3058 * set_current_blocked - change current->blocked mask
3059 * @newset: new mask
3060 *
3061 * It is wrong to change ->blocked directly, this helper should be used
3062 * to ensure the process can't miss a shared signal we are going to block.
3063 */
3064void set_current_blocked(sigset_t *newset)
3065{
3066 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3067 __set_current_blocked(newset);
3068}
3069
3070void __set_current_blocked(const sigset_t *newset)
3071{
3072 struct task_struct *tsk = current;
3073
3074 /*
3075 * In case the signal mask hasn't changed, there is nothing we need
3076 * to do. The current->blocked shouldn't be modified by other task.
3077 */
3078 if (sigequalsets(&tsk->blocked, newset))
3079 return;
3080
3081 spin_lock_irq(&tsk->sighand->siglock);
3082 __set_task_blocked(tsk, newset);
3083 spin_unlock_irq(&tsk->sighand->siglock);
3084}
3085
3086/*
3087 * This is also useful for kernel threads that want to temporarily
3088 * (or permanently) block certain signals.
3089 *
3090 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3091 * interface happily blocks "unblockable" signals like SIGKILL
3092 * and friends.
3093 */
3094int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3095{
3096 struct task_struct *tsk = current;
3097 sigset_t newset;
3098
3099 /* Lockless, only current can change ->blocked, never from irq */
3100 if (oldset)
3101 *oldset = tsk->blocked;
3102
3103 switch (how) {
3104 case SIG_BLOCK:
3105 sigorsets(&newset, &tsk->blocked, set);
3106 break;
3107 case SIG_UNBLOCK:
3108 sigandnsets(&newset, &tsk->blocked, set);
3109 break;
3110 case SIG_SETMASK:
3111 newset = *set;
3112 break;
3113 default:
3114 return -EINVAL;
3115 }
3116
3117 __set_current_blocked(&newset);
3118 return 0;
3119}
3120EXPORT_SYMBOL(sigprocmask);
3121
3122/*
3123 * The api helps set app-provided sigmasks.
3124 *
3125 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3126 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3127 *
3128 * Note that it does set_restore_sigmask() in advance, so it must be always
3129 * paired with restore_saved_sigmask_unless() before return from syscall.
3130 */
3131int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3132{
3133 sigset_t kmask;
3134
3135 if (!umask)
3136 return 0;
3137 if (sigsetsize != sizeof(sigset_t))
3138 return -EINVAL;
3139 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3140 return -EFAULT;
3141
3142 set_restore_sigmask();
3143 current->saved_sigmask = current->blocked;
3144 set_current_blocked(&kmask);
3145
3146 return 0;
3147}
3148
3149#ifdef CONFIG_COMPAT
3150int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3151 size_t sigsetsize)
3152{
3153 sigset_t kmask;
3154
3155 if (!umask)
3156 return 0;
3157 if (sigsetsize != sizeof(compat_sigset_t))
3158 return -EINVAL;
3159 if (get_compat_sigset(&kmask, umask))
3160 return -EFAULT;
3161
3162 set_restore_sigmask();
3163 current->saved_sigmask = current->blocked;
3164 set_current_blocked(&kmask);
3165
3166 return 0;
3167}
3168#endif
3169
3170/**
3171 * sys_rt_sigprocmask - change the list of currently blocked signals
3172 * @how: whether to add, remove, or set signals
3173 * @nset: stores pending signals
3174 * @oset: previous value of signal mask if non-null
3175 * @sigsetsize: size of sigset_t type
3176 */
3177SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3178 sigset_t __user *, oset, size_t, sigsetsize)
3179{
3180 sigset_t old_set, new_set;
3181 int error;
3182
3183 /* XXX: Don't preclude handling different sized sigset_t's. */
3184 if (sigsetsize != sizeof(sigset_t))
3185 return -EINVAL;
3186
3187 old_set = current->blocked;
3188
3189 if (nset) {
3190 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3191 return -EFAULT;
3192 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3193
3194 error = sigprocmask(how, &new_set, NULL);
3195 if (error)
3196 return error;
3197 }
3198
3199 if (oset) {
3200 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3201 return -EFAULT;
3202 }
3203
3204 return 0;
3205}
3206
3207#ifdef CONFIG_COMPAT
3208COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3209 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3210{
3211 sigset_t old_set = current->blocked;
3212
3213 /* XXX: Don't preclude handling different sized sigset_t's. */
3214 if (sigsetsize != sizeof(sigset_t))
3215 return -EINVAL;
3216
3217 if (nset) {
3218 sigset_t new_set;
3219 int error;
3220 if (get_compat_sigset(&new_set, nset))
3221 return -EFAULT;
3222 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3223
3224 error = sigprocmask(how, &new_set, NULL);
3225 if (error)
3226 return error;
3227 }
3228 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3229}
3230#endif
3231
3232static void do_sigpending(sigset_t *set)
3233{
3234 spin_lock_irq(¤t->sighand->siglock);
3235 sigorsets(set, ¤t->pending.signal,
3236 ¤t->signal->shared_pending.signal);
3237 spin_unlock_irq(¤t->sighand->siglock);
3238
3239 /* Outside the lock because only this thread touches it. */
3240 sigandsets(set, ¤t->blocked, set);
3241}
3242
3243/**
3244 * sys_rt_sigpending - examine a pending signal that has been raised
3245 * while blocked
3246 * @uset: stores pending signals
3247 * @sigsetsize: size of sigset_t type or larger
3248 */
3249SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3250{
3251 sigset_t set;
3252
3253 if (sigsetsize > sizeof(*uset))
3254 return -EINVAL;
3255
3256 do_sigpending(&set);
3257
3258 if (copy_to_user(uset, &set, sigsetsize))
3259 return -EFAULT;
3260
3261 return 0;
3262}
3263
3264#ifdef CONFIG_COMPAT
3265COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3266 compat_size_t, sigsetsize)
3267{
3268 sigset_t set;
3269
3270 if (sigsetsize > sizeof(*uset))
3271 return -EINVAL;
3272
3273 do_sigpending(&set);
3274
3275 return put_compat_sigset(uset, &set, sigsetsize);
3276}
3277#endif
3278
3279static const struct {
3280 unsigned char limit, layout;
3281} sig_sicodes[] = {
3282 [SIGILL] = { NSIGILL, SIL_FAULT },
3283 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3284 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3285 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3286 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3287#if defined(SIGEMT)
3288 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3289#endif
3290 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3291 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3292 [SIGSYS] = { NSIGSYS, SIL_SYS },
3293};
3294
3295static bool known_siginfo_layout(unsigned sig, int si_code)
3296{
3297 if (si_code == SI_KERNEL)
3298 return true;
3299 else if ((si_code > SI_USER)) {
3300 if (sig_specific_sicodes(sig)) {
3301 if (si_code <= sig_sicodes[sig].limit)
3302 return true;
3303 }
3304 else if (si_code <= NSIGPOLL)
3305 return true;
3306 }
3307 else if (si_code >= SI_DETHREAD)
3308 return true;
3309 else if (si_code == SI_ASYNCNL)
3310 return true;
3311 return false;
3312}
3313
3314enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3315{
3316 enum siginfo_layout layout = SIL_KILL;
3317 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3318 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3319 (si_code <= sig_sicodes[sig].limit)) {
3320 layout = sig_sicodes[sig].layout;
3321 /* Handle the exceptions */
3322 if ((sig == SIGBUS) &&
3323 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3324 layout = SIL_FAULT_MCEERR;
3325 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3326 layout = SIL_FAULT_BNDERR;
3327#ifdef SEGV_PKUERR
3328 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3329 layout = SIL_FAULT_PKUERR;
3330#endif
3331 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3332 layout = SIL_FAULT_PERF_EVENT;
3333 else if (IS_ENABLED(CONFIG_SPARC) &&
3334 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3335 layout = SIL_FAULT_TRAPNO;
3336 else if (IS_ENABLED(CONFIG_ALPHA) &&
3337 ((sig == SIGFPE) ||
3338 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3339 layout = SIL_FAULT_TRAPNO;
3340 }
3341 else if (si_code <= NSIGPOLL)
3342 layout = SIL_POLL;
3343 } else {
3344 if (si_code == SI_TIMER)
3345 layout = SIL_TIMER;
3346 else if (si_code == SI_SIGIO)
3347 layout = SIL_POLL;
3348 else if (si_code < 0)
3349 layout = SIL_RT;
3350 }
3351 return layout;
3352}
3353
3354static inline char __user *si_expansion(const siginfo_t __user *info)
3355{
3356 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3357}
3358
3359int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3360{
3361 char __user *expansion = si_expansion(to);
3362 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3363 return -EFAULT;
3364 if (clear_user(expansion, SI_EXPANSION_SIZE))
3365 return -EFAULT;
3366 return 0;
3367}
3368
3369static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3370 const siginfo_t __user *from)
3371{
3372 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3373 char __user *expansion = si_expansion(from);
3374 char buf[SI_EXPANSION_SIZE];
3375 int i;
3376 /*
3377 * An unknown si_code might need more than
3378 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3379 * extra bytes are 0. This guarantees copy_siginfo_to_user
3380 * will return this data to userspace exactly.
3381 */
3382 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3383 return -EFAULT;
3384 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3385 if (buf[i] != 0)
3386 return -E2BIG;
3387 }
3388 }
3389 return 0;
3390}
3391
3392static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3393 const siginfo_t __user *from)
3394{
3395 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3396 return -EFAULT;
3397 to->si_signo = signo;
3398 return post_copy_siginfo_from_user(to, from);
3399}
3400
3401int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3402{
3403 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3404 return -EFAULT;
3405 return post_copy_siginfo_from_user(to, from);
3406}
3407
3408#ifdef CONFIG_COMPAT
3409/**
3410 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3411 * @to: compat siginfo destination
3412 * @from: kernel siginfo source
3413 *
3414 * Note: This function does not work properly for the SIGCHLD on x32, but
3415 * fortunately it doesn't have to. The only valid callers for this function are
3416 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3417 * The latter does not care because SIGCHLD will never cause a coredump.
3418 */
3419void copy_siginfo_to_external32(struct compat_siginfo *to,
3420 const struct kernel_siginfo *from)
3421{
3422 memset(to, 0, sizeof(*to));
3423
3424 to->si_signo = from->si_signo;
3425 to->si_errno = from->si_errno;
3426 to->si_code = from->si_code;
3427 switch(siginfo_layout(from->si_signo, from->si_code)) {
3428 case SIL_KILL:
3429 to->si_pid = from->si_pid;
3430 to->si_uid = from->si_uid;
3431 break;
3432 case SIL_TIMER:
3433 to->si_tid = from->si_tid;
3434 to->si_overrun = from->si_overrun;
3435 to->si_int = from->si_int;
3436 break;
3437 case SIL_POLL:
3438 to->si_band = from->si_band;
3439 to->si_fd = from->si_fd;
3440 break;
3441 case SIL_FAULT:
3442 to->si_addr = ptr_to_compat(from->si_addr);
3443 break;
3444 case SIL_FAULT_TRAPNO:
3445 to->si_addr = ptr_to_compat(from->si_addr);
3446 to->si_trapno = from->si_trapno;
3447 break;
3448 case SIL_FAULT_MCEERR:
3449 to->si_addr = ptr_to_compat(from->si_addr);
3450 to->si_addr_lsb = from->si_addr_lsb;
3451 break;
3452 case SIL_FAULT_BNDERR:
3453 to->si_addr = ptr_to_compat(from->si_addr);
3454 to->si_lower = ptr_to_compat(from->si_lower);
3455 to->si_upper = ptr_to_compat(from->si_upper);
3456 break;
3457 case SIL_FAULT_PKUERR:
3458 to->si_addr = ptr_to_compat(from->si_addr);
3459 to->si_pkey = from->si_pkey;
3460 break;
3461 case SIL_FAULT_PERF_EVENT:
3462 to->si_addr = ptr_to_compat(from->si_addr);
3463 to->si_perf_data = from->si_perf_data;
3464 to->si_perf_type = from->si_perf_type;
3465 to->si_perf_flags = from->si_perf_flags;
3466 break;
3467 case SIL_CHLD:
3468 to->si_pid = from->si_pid;
3469 to->si_uid = from->si_uid;
3470 to->si_status = from->si_status;
3471 to->si_utime = from->si_utime;
3472 to->si_stime = from->si_stime;
3473 break;
3474 case SIL_RT:
3475 to->si_pid = from->si_pid;
3476 to->si_uid = from->si_uid;
3477 to->si_int = from->si_int;
3478 break;
3479 case SIL_SYS:
3480 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3481 to->si_syscall = from->si_syscall;
3482 to->si_arch = from->si_arch;
3483 break;
3484 }
3485}
3486
3487int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3488 const struct kernel_siginfo *from)
3489{
3490 struct compat_siginfo new;
3491
3492 copy_siginfo_to_external32(&new, from);
3493 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3494 return -EFAULT;
3495 return 0;
3496}
3497
3498static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3499 const struct compat_siginfo *from)
3500{
3501 clear_siginfo(to);
3502 to->si_signo = from->si_signo;
3503 to->si_errno = from->si_errno;
3504 to->si_code = from->si_code;
3505 switch(siginfo_layout(from->si_signo, from->si_code)) {
3506 case SIL_KILL:
3507 to->si_pid = from->si_pid;
3508 to->si_uid = from->si_uid;
3509 break;
3510 case SIL_TIMER:
3511 to->si_tid = from->si_tid;
3512 to->si_overrun = from->si_overrun;
3513 to->si_int = from->si_int;
3514 break;
3515 case SIL_POLL:
3516 to->si_band = from->si_band;
3517 to->si_fd = from->si_fd;
3518 break;
3519 case SIL_FAULT:
3520 to->si_addr = compat_ptr(from->si_addr);
3521 break;
3522 case SIL_FAULT_TRAPNO:
3523 to->si_addr = compat_ptr(from->si_addr);
3524 to->si_trapno = from->si_trapno;
3525 break;
3526 case SIL_FAULT_MCEERR:
3527 to->si_addr = compat_ptr(from->si_addr);
3528 to->si_addr_lsb = from->si_addr_lsb;
3529 break;
3530 case SIL_FAULT_BNDERR:
3531 to->si_addr = compat_ptr(from->si_addr);
3532 to->si_lower = compat_ptr(from->si_lower);
3533 to->si_upper = compat_ptr(from->si_upper);
3534 break;
3535 case SIL_FAULT_PKUERR:
3536 to->si_addr = compat_ptr(from->si_addr);
3537 to->si_pkey = from->si_pkey;
3538 break;
3539 case SIL_FAULT_PERF_EVENT:
3540 to->si_addr = compat_ptr(from->si_addr);
3541 to->si_perf_data = from->si_perf_data;
3542 to->si_perf_type = from->si_perf_type;
3543 to->si_perf_flags = from->si_perf_flags;
3544 break;
3545 case SIL_CHLD:
3546 to->si_pid = from->si_pid;
3547 to->si_uid = from->si_uid;
3548 to->si_status = from->si_status;
3549#ifdef CONFIG_X86_X32_ABI
3550 if (in_x32_syscall()) {
3551 to->si_utime = from->_sifields._sigchld_x32._utime;
3552 to->si_stime = from->_sifields._sigchld_x32._stime;
3553 } else
3554#endif
3555 {
3556 to->si_utime = from->si_utime;
3557 to->si_stime = from->si_stime;
3558 }
3559 break;
3560 case SIL_RT:
3561 to->si_pid = from->si_pid;
3562 to->si_uid = from->si_uid;
3563 to->si_int = from->si_int;
3564 break;
3565 case SIL_SYS:
3566 to->si_call_addr = compat_ptr(from->si_call_addr);
3567 to->si_syscall = from->si_syscall;
3568 to->si_arch = from->si_arch;
3569 break;
3570 }
3571 return 0;
3572}
3573
3574static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3575 const struct compat_siginfo __user *ufrom)
3576{
3577 struct compat_siginfo from;
3578
3579 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3580 return -EFAULT;
3581
3582 from.si_signo = signo;
3583 return post_copy_siginfo_from_user32(to, &from);
3584}
3585
3586int copy_siginfo_from_user32(struct kernel_siginfo *to,
3587 const struct compat_siginfo __user *ufrom)
3588{
3589 struct compat_siginfo from;
3590
3591 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3592 return -EFAULT;
3593
3594 return post_copy_siginfo_from_user32(to, &from);
3595}
3596#endif /* CONFIG_COMPAT */
3597
3598/**
3599 * do_sigtimedwait - wait for queued signals specified in @which
3600 * @which: queued signals to wait for
3601 * @info: if non-null, the signal's siginfo is returned here
3602 * @ts: upper bound on process time suspension
3603 */
3604static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3605 const struct timespec64 *ts)
3606{
3607 ktime_t *to = NULL, timeout = KTIME_MAX;
3608 struct task_struct *tsk = current;
3609 sigset_t mask = *which;
3610 enum pid_type type;
3611 int sig, ret = 0;
3612
3613 if (ts) {
3614 if (!timespec64_valid(ts))
3615 return -EINVAL;
3616 timeout = timespec64_to_ktime(*ts);
3617 to = &timeout;
3618 }
3619
3620 /*
3621 * Invert the set of allowed signals to get those we want to block.
3622 */
3623 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3624 signotset(&mask);
3625
3626 spin_lock_irq(&tsk->sighand->siglock);
3627 sig = dequeue_signal(tsk, &mask, info, &type);
3628 if (!sig && timeout) {
3629 /*
3630 * None ready, temporarily unblock those we're interested
3631 * while we are sleeping in so that we'll be awakened when
3632 * they arrive. Unblocking is always fine, we can avoid
3633 * set_current_blocked().
3634 */
3635 tsk->real_blocked = tsk->blocked;
3636 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3637 recalc_sigpending();
3638 spin_unlock_irq(&tsk->sighand->siglock);
3639
3640 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3641 ret = schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3642 HRTIMER_MODE_REL);
3643 spin_lock_irq(&tsk->sighand->siglock);
3644 __set_task_blocked(tsk, &tsk->real_blocked);
3645 sigemptyset(&tsk->real_blocked);
3646 sig = dequeue_signal(tsk, &mask, info, &type);
3647 }
3648 spin_unlock_irq(&tsk->sighand->siglock);
3649
3650 if (sig)
3651 return sig;
3652 return ret ? -EINTR : -EAGAIN;
3653}
3654
3655/**
3656 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3657 * in @uthese
3658 * @uthese: queued signals to wait for
3659 * @uinfo: if non-null, the signal's siginfo is returned here
3660 * @uts: upper bound on process time suspension
3661 * @sigsetsize: size of sigset_t type
3662 */
3663SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3664 siginfo_t __user *, uinfo,
3665 const struct __kernel_timespec __user *, uts,
3666 size_t, sigsetsize)
3667{
3668 sigset_t these;
3669 struct timespec64 ts;
3670 kernel_siginfo_t info;
3671 int ret;
3672
3673 /* XXX: Don't preclude handling different sized sigset_t's. */
3674 if (sigsetsize != sizeof(sigset_t))
3675 return -EINVAL;
3676
3677 if (copy_from_user(&these, uthese, sizeof(these)))
3678 return -EFAULT;
3679
3680 if (uts) {
3681 if (get_timespec64(&ts, uts))
3682 return -EFAULT;
3683 }
3684
3685 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3686
3687 if (ret > 0 && uinfo) {
3688 if (copy_siginfo_to_user(uinfo, &info))
3689 ret = -EFAULT;
3690 }
3691
3692 return ret;
3693}
3694
3695#ifdef CONFIG_COMPAT_32BIT_TIME
3696SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3697 siginfo_t __user *, uinfo,
3698 const struct old_timespec32 __user *, uts,
3699 size_t, sigsetsize)
3700{
3701 sigset_t these;
3702 struct timespec64 ts;
3703 kernel_siginfo_t info;
3704 int ret;
3705
3706 if (sigsetsize != sizeof(sigset_t))
3707 return -EINVAL;
3708
3709 if (copy_from_user(&these, uthese, sizeof(these)))
3710 return -EFAULT;
3711
3712 if (uts) {
3713 if (get_old_timespec32(&ts, uts))
3714 return -EFAULT;
3715 }
3716
3717 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3718
3719 if (ret > 0 && uinfo) {
3720 if (copy_siginfo_to_user(uinfo, &info))
3721 ret = -EFAULT;
3722 }
3723
3724 return ret;
3725}
3726#endif
3727
3728#ifdef CONFIG_COMPAT
3729COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3730 struct compat_siginfo __user *, uinfo,
3731 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3732{
3733 sigset_t s;
3734 struct timespec64 t;
3735 kernel_siginfo_t info;
3736 long ret;
3737
3738 if (sigsetsize != sizeof(sigset_t))
3739 return -EINVAL;
3740
3741 if (get_compat_sigset(&s, uthese))
3742 return -EFAULT;
3743
3744 if (uts) {
3745 if (get_timespec64(&t, uts))
3746 return -EFAULT;
3747 }
3748
3749 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3750
3751 if (ret > 0 && uinfo) {
3752 if (copy_siginfo_to_user32(uinfo, &info))
3753 ret = -EFAULT;
3754 }
3755
3756 return ret;
3757}
3758
3759#ifdef CONFIG_COMPAT_32BIT_TIME
3760COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3761 struct compat_siginfo __user *, uinfo,
3762 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3763{
3764 sigset_t s;
3765 struct timespec64 t;
3766 kernel_siginfo_t info;
3767 long ret;
3768
3769 if (sigsetsize != sizeof(sigset_t))
3770 return -EINVAL;
3771
3772 if (get_compat_sigset(&s, uthese))
3773 return -EFAULT;
3774
3775 if (uts) {
3776 if (get_old_timespec32(&t, uts))
3777 return -EFAULT;
3778 }
3779
3780 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3781
3782 if (ret > 0 && uinfo) {
3783 if (copy_siginfo_to_user32(uinfo, &info))
3784 ret = -EFAULT;
3785 }
3786
3787 return ret;
3788}
3789#endif
3790#endif
3791
3792static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3793{
3794 clear_siginfo(info);
3795 info->si_signo = sig;
3796 info->si_errno = 0;
3797 info->si_code = SI_USER;
3798 info->si_pid = task_tgid_vnr(current);
3799 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3800}
3801
3802/**
3803 * sys_kill - send a signal to a process
3804 * @pid: the PID of the process
3805 * @sig: signal to be sent
3806 */
3807SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3808{
3809 struct kernel_siginfo info;
3810
3811 prepare_kill_siginfo(sig, &info);
3812
3813 return kill_something_info(sig, &info, pid);
3814}
3815
3816/*
3817 * Verify that the signaler and signalee either are in the same pid namespace
3818 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3819 * namespace.
3820 */
3821static bool access_pidfd_pidns(struct pid *pid)
3822{
3823 struct pid_namespace *active = task_active_pid_ns(current);
3824 struct pid_namespace *p = ns_of_pid(pid);
3825
3826 for (;;) {
3827 if (!p)
3828 return false;
3829 if (p == active)
3830 break;
3831 p = p->parent;
3832 }
3833
3834 return true;
3835}
3836
3837static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3838 siginfo_t __user *info)
3839{
3840#ifdef CONFIG_COMPAT
3841 /*
3842 * Avoid hooking up compat syscalls and instead handle necessary
3843 * conversions here. Note, this is a stop-gap measure and should not be
3844 * considered a generic solution.
3845 */
3846 if (in_compat_syscall())
3847 return copy_siginfo_from_user32(
3848 kinfo, (struct compat_siginfo __user *)info);
3849#endif
3850 return copy_siginfo_from_user(kinfo, info);
3851}
3852
3853static struct pid *pidfd_to_pid(const struct file *file)
3854{
3855 struct pid *pid;
3856
3857 pid = pidfd_pid(file);
3858 if (!IS_ERR(pid))
3859 return pid;
3860
3861 return tgid_pidfd_to_pid(file);
3862}
3863
3864/**
3865 * sys_pidfd_send_signal - Signal a process through a pidfd
3866 * @pidfd: file descriptor of the process
3867 * @sig: signal to send
3868 * @info: signal info
3869 * @flags: future flags
3870 *
3871 * The syscall currently only signals via PIDTYPE_PID which covers
3872 * kill(<positive-pid>, <signal>. It does not signal threads or process
3873 * groups.
3874 * In order to extend the syscall to threads and process groups the @flags
3875 * argument should be used. In essence, the @flags argument will determine
3876 * what is signaled and not the file descriptor itself. Put in other words,
3877 * grouping is a property of the flags argument not a property of the file
3878 * descriptor.
3879 *
3880 * Return: 0 on success, negative errno on failure
3881 */
3882SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3883 siginfo_t __user *, info, unsigned int, flags)
3884{
3885 int ret;
3886 struct fd f;
3887 struct pid *pid;
3888 kernel_siginfo_t kinfo;
3889
3890 /* Enforce flags be set to 0 until we add an extension. */
3891 if (flags)
3892 return -EINVAL;
3893
3894 f = fdget(pidfd);
3895 if (!f.file)
3896 return -EBADF;
3897
3898 /* Is this a pidfd? */
3899 pid = pidfd_to_pid(f.file);
3900 if (IS_ERR(pid)) {
3901 ret = PTR_ERR(pid);
3902 goto err;
3903 }
3904
3905 ret = -EINVAL;
3906 if (!access_pidfd_pidns(pid))
3907 goto err;
3908
3909 if (info) {
3910 ret = copy_siginfo_from_user_any(&kinfo, info);
3911 if (unlikely(ret))
3912 goto err;
3913
3914 ret = -EINVAL;
3915 if (unlikely(sig != kinfo.si_signo))
3916 goto err;
3917
3918 /* Only allow sending arbitrary signals to yourself. */
3919 ret = -EPERM;
3920 if ((task_pid(current) != pid) &&
3921 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3922 goto err;
3923 } else {
3924 prepare_kill_siginfo(sig, &kinfo);
3925 }
3926
3927 ret = kill_pid_info(sig, &kinfo, pid);
3928
3929err:
3930 fdput(f);
3931 return ret;
3932}
3933
3934static int
3935do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3936{
3937 struct task_struct *p;
3938 int error = -ESRCH;
3939
3940 rcu_read_lock();
3941 p = find_task_by_vpid(pid);
3942 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3943 error = check_kill_permission(sig, info, p);
3944 /*
3945 * The null signal is a permissions and process existence
3946 * probe. No signal is actually delivered.
3947 */
3948 if (!error && sig) {
3949 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3950 /*
3951 * If lock_task_sighand() failed we pretend the task
3952 * dies after receiving the signal. The window is tiny,
3953 * and the signal is private anyway.
3954 */
3955 if (unlikely(error == -ESRCH))
3956 error = 0;
3957 }
3958 }
3959 rcu_read_unlock();
3960
3961 return error;
3962}
3963
3964static int do_tkill(pid_t tgid, pid_t pid, int sig)
3965{
3966 struct kernel_siginfo info;
3967
3968 clear_siginfo(&info);
3969 info.si_signo = sig;
3970 info.si_errno = 0;
3971 info.si_code = SI_TKILL;
3972 info.si_pid = task_tgid_vnr(current);
3973 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3974
3975 return do_send_specific(tgid, pid, sig, &info);
3976}
3977
3978/**
3979 * sys_tgkill - send signal to one specific thread
3980 * @tgid: the thread group ID of the thread
3981 * @pid: the PID of the thread
3982 * @sig: signal to be sent
3983 *
3984 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3985 * exists but it's not belonging to the target process anymore. This
3986 * method solves the problem of threads exiting and PIDs getting reused.
3987 */
3988SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3989{
3990 /* This is only valid for single tasks */
3991 if (pid <= 0 || tgid <= 0)
3992 return -EINVAL;
3993
3994 return do_tkill(tgid, pid, sig);
3995}
3996
3997/**
3998 * sys_tkill - send signal to one specific task
3999 * @pid: the PID of the task
4000 * @sig: signal to be sent
4001 *
4002 * Send a signal to only one task, even if it's a CLONE_THREAD task.
4003 */
4004SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4005{
4006 /* This is only valid for single tasks */
4007 if (pid <= 0)
4008 return -EINVAL;
4009
4010 return do_tkill(0, pid, sig);
4011}
4012
4013static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4014{
4015 /* Not even root can pretend to send signals from the kernel.
4016 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4017 */
4018 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4019 (task_pid_vnr(current) != pid))
4020 return -EPERM;
4021
4022 /* POSIX.1b doesn't mention process groups. */
4023 return kill_proc_info(sig, info, pid);
4024}
4025
4026/**
4027 * sys_rt_sigqueueinfo - send signal information to a signal
4028 * @pid: the PID of the thread
4029 * @sig: signal to be sent
4030 * @uinfo: signal info to be sent
4031 */
4032SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4033 siginfo_t __user *, uinfo)
4034{
4035 kernel_siginfo_t info;
4036 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4037 if (unlikely(ret))
4038 return ret;
4039 return do_rt_sigqueueinfo(pid, sig, &info);
4040}
4041
4042#ifdef CONFIG_COMPAT
4043COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4044 compat_pid_t, pid,
4045 int, sig,
4046 struct compat_siginfo __user *, uinfo)
4047{
4048 kernel_siginfo_t info;
4049 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4050 if (unlikely(ret))
4051 return ret;
4052 return do_rt_sigqueueinfo(pid, sig, &info);
4053}
4054#endif
4055
4056static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4057{
4058 /* This is only valid for single tasks */
4059 if (pid <= 0 || tgid <= 0)
4060 return -EINVAL;
4061
4062 /* Not even root can pretend to send signals from the kernel.
4063 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4064 */
4065 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4066 (task_pid_vnr(current) != pid))
4067 return -EPERM;
4068
4069 return do_send_specific(tgid, pid, sig, info);
4070}
4071
4072SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4073 siginfo_t __user *, uinfo)
4074{
4075 kernel_siginfo_t info;
4076 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4077 if (unlikely(ret))
4078 return ret;
4079 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4080}
4081
4082#ifdef CONFIG_COMPAT
4083COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4084 compat_pid_t, tgid,
4085 compat_pid_t, pid,
4086 int, sig,
4087 struct compat_siginfo __user *, uinfo)
4088{
4089 kernel_siginfo_t info;
4090 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4091 if (unlikely(ret))
4092 return ret;
4093 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4094}
4095#endif
4096
4097/*
4098 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4099 */
4100void kernel_sigaction(int sig, __sighandler_t action)
4101{
4102 spin_lock_irq(¤t->sighand->siglock);
4103 current->sighand->action[sig - 1].sa.sa_handler = action;
4104 if (action == SIG_IGN) {
4105 sigset_t mask;
4106
4107 sigemptyset(&mask);
4108 sigaddset(&mask, sig);
4109
4110 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4111 flush_sigqueue_mask(&mask, ¤t->pending);
4112 recalc_sigpending();
4113 }
4114 spin_unlock_irq(¤t->sighand->siglock);
4115}
4116EXPORT_SYMBOL(kernel_sigaction);
4117
4118void __weak sigaction_compat_abi(struct k_sigaction *act,
4119 struct k_sigaction *oact)
4120{
4121}
4122
4123int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4124{
4125 struct task_struct *p = current, *t;
4126 struct k_sigaction *k;
4127 sigset_t mask;
4128
4129 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4130 return -EINVAL;
4131
4132 k = &p->sighand->action[sig-1];
4133
4134 spin_lock_irq(&p->sighand->siglock);
4135 if (k->sa.sa_flags & SA_IMMUTABLE) {
4136 spin_unlock_irq(&p->sighand->siglock);
4137 return -EINVAL;
4138 }
4139 if (oact)
4140 *oact = *k;
4141
4142 /*
4143 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4144 * e.g. by having an architecture use the bit in their uapi.
4145 */
4146 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4147
4148 /*
4149 * Clear unknown flag bits in order to allow userspace to detect missing
4150 * support for flag bits and to allow the kernel to use non-uapi bits
4151 * internally.
4152 */
4153 if (act)
4154 act->sa.sa_flags &= UAPI_SA_FLAGS;
4155 if (oact)
4156 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4157
4158 sigaction_compat_abi(act, oact);
4159
4160 if (act) {
4161 sigdelsetmask(&act->sa.sa_mask,
4162 sigmask(SIGKILL) | sigmask(SIGSTOP));
4163 *k = *act;
4164 /*
4165 * POSIX 3.3.1.3:
4166 * "Setting a signal action to SIG_IGN for a signal that is
4167 * pending shall cause the pending signal to be discarded,
4168 * whether or not it is blocked."
4169 *
4170 * "Setting a signal action to SIG_DFL for a signal that is
4171 * pending and whose default action is to ignore the signal
4172 * (for example, SIGCHLD), shall cause the pending signal to
4173 * be discarded, whether or not it is blocked"
4174 */
4175 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4176 sigemptyset(&mask);
4177 sigaddset(&mask, sig);
4178 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4179 for_each_thread(p, t)
4180 flush_sigqueue_mask(&mask, &t->pending);
4181 }
4182 }
4183
4184 spin_unlock_irq(&p->sighand->siglock);
4185 return 0;
4186}
4187
4188#ifdef CONFIG_DYNAMIC_SIGFRAME
4189static inline void sigaltstack_lock(void)
4190 __acquires(¤t->sighand->siglock)
4191{
4192 spin_lock_irq(¤t->sighand->siglock);
4193}
4194
4195static inline void sigaltstack_unlock(void)
4196 __releases(¤t->sighand->siglock)
4197{
4198 spin_unlock_irq(¤t->sighand->siglock);
4199}
4200#else
4201static inline void sigaltstack_lock(void) { }
4202static inline void sigaltstack_unlock(void) { }
4203#endif
4204
4205static int
4206do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4207 size_t min_ss_size)
4208{
4209 struct task_struct *t = current;
4210 int ret = 0;
4211
4212 if (oss) {
4213 memset(oss, 0, sizeof(stack_t));
4214 oss->ss_sp = (void __user *) t->sas_ss_sp;
4215 oss->ss_size = t->sas_ss_size;
4216 oss->ss_flags = sas_ss_flags(sp) |
4217 (current->sas_ss_flags & SS_FLAG_BITS);
4218 }
4219
4220 if (ss) {
4221 void __user *ss_sp = ss->ss_sp;
4222 size_t ss_size = ss->ss_size;
4223 unsigned ss_flags = ss->ss_flags;
4224 int ss_mode;
4225
4226 if (unlikely(on_sig_stack(sp)))
4227 return -EPERM;
4228
4229 ss_mode = ss_flags & ~SS_FLAG_BITS;
4230 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4231 ss_mode != 0))
4232 return -EINVAL;
4233
4234 /*
4235 * Return before taking any locks if no actual
4236 * sigaltstack changes were requested.
4237 */
4238 if (t->sas_ss_sp == (unsigned long)ss_sp &&
4239 t->sas_ss_size == ss_size &&
4240 t->sas_ss_flags == ss_flags)
4241 return 0;
4242
4243 sigaltstack_lock();
4244 if (ss_mode == SS_DISABLE) {
4245 ss_size = 0;
4246 ss_sp = NULL;
4247 } else {
4248 if (unlikely(ss_size < min_ss_size))
4249 ret = -ENOMEM;
4250 if (!sigaltstack_size_valid(ss_size))
4251 ret = -ENOMEM;
4252 }
4253 if (!ret) {
4254 t->sas_ss_sp = (unsigned long) ss_sp;
4255 t->sas_ss_size = ss_size;
4256 t->sas_ss_flags = ss_flags;
4257 }
4258 sigaltstack_unlock();
4259 }
4260 return ret;
4261}
4262
4263SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4264{
4265 stack_t new, old;
4266 int err;
4267 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4268 return -EFAULT;
4269 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4270 current_user_stack_pointer(),
4271 MINSIGSTKSZ);
4272 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4273 err = -EFAULT;
4274 return err;
4275}
4276
4277int restore_altstack(const stack_t __user *uss)
4278{
4279 stack_t new;
4280 if (copy_from_user(&new, uss, sizeof(stack_t)))
4281 return -EFAULT;
4282 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4283 MINSIGSTKSZ);
4284 /* squash all but EFAULT for now */
4285 return 0;
4286}
4287
4288int __save_altstack(stack_t __user *uss, unsigned long sp)
4289{
4290 struct task_struct *t = current;
4291 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4292 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4293 __put_user(t->sas_ss_size, &uss->ss_size);
4294 return err;
4295}
4296
4297#ifdef CONFIG_COMPAT
4298static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4299 compat_stack_t __user *uoss_ptr)
4300{
4301 stack_t uss, uoss;
4302 int ret;
4303
4304 if (uss_ptr) {
4305 compat_stack_t uss32;
4306 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4307 return -EFAULT;
4308 uss.ss_sp = compat_ptr(uss32.ss_sp);
4309 uss.ss_flags = uss32.ss_flags;
4310 uss.ss_size = uss32.ss_size;
4311 }
4312 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4313 compat_user_stack_pointer(),
4314 COMPAT_MINSIGSTKSZ);
4315 if (ret >= 0 && uoss_ptr) {
4316 compat_stack_t old;
4317 memset(&old, 0, sizeof(old));
4318 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4319 old.ss_flags = uoss.ss_flags;
4320 old.ss_size = uoss.ss_size;
4321 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4322 ret = -EFAULT;
4323 }
4324 return ret;
4325}
4326
4327COMPAT_SYSCALL_DEFINE2(sigaltstack,
4328 const compat_stack_t __user *, uss_ptr,
4329 compat_stack_t __user *, uoss_ptr)
4330{
4331 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4332}
4333
4334int compat_restore_altstack(const compat_stack_t __user *uss)
4335{
4336 int err = do_compat_sigaltstack(uss, NULL);
4337 /* squash all but -EFAULT for now */
4338 return err == -EFAULT ? err : 0;
4339}
4340
4341int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4342{
4343 int err;
4344 struct task_struct *t = current;
4345 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4346 &uss->ss_sp) |
4347 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4348 __put_user(t->sas_ss_size, &uss->ss_size);
4349 return err;
4350}
4351#endif
4352
4353#ifdef __ARCH_WANT_SYS_SIGPENDING
4354
4355/**
4356 * sys_sigpending - examine pending signals
4357 * @uset: where mask of pending signal is returned
4358 */
4359SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4360{
4361 sigset_t set;
4362
4363 if (sizeof(old_sigset_t) > sizeof(*uset))
4364 return -EINVAL;
4365
4366 do_sigpending(&set);
4367
4368 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4369 return -EFAULT;
4370
4371 return 0;
4372}
4373
4374#ifdef CONFIG_COMPAT
4375COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4376{
4377 sigset_t set;
4378
4379 do_sigpending(&set);
4380
4381 return put_user(set.sig[0], set32);
4382}
4383#endif
4384
4385#endif
4386
4387#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4388/**
4389 * sys_sigprocmask - examine and change blocked signals
4390 * @how: whether to add, remove, or set signals
4391 * @nset: signals to add or remove (if non-null)
4392 * @oset: previous value of signal mask if non-null
4393 *
4394 * Some platforms have their own version with special arguments;
4395 * others support only sys_rt_sigprocmask.
4396 */
4397
4398SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4399 old_sigset_t __user *, oset)
4400{
4401 old_sigset_t old_set, new_set;
4402 sigset_t new_blocked;
4403
4404 old_set = current->blocked.sig[0];
4405
4406 if (nset) {
4407 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4408 return -EFAULT;
4409
4410 new_blocked = current->blocked;
4411
4412 switch (how) {
4413 case SIG_BLOCK:
4414 sigaddsetmask(&new_blocked, new_set);
4415 break;
4416 case SIG_UNBLOCK:
4417 sigdelsetmask(&new_blocked, new_set);
4418 break;
4419 case SIG_SETMASK:
4420 new_blocked.sig[0] = new_set;
4421 break;
4422 default:
4423 return -EINVAL;
4424 }
4425
4426 set_current_blocked(&new_blocked);
4427 }
4428
4429 if (oset) {
4430 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4431 return -EFAULT;
4432 }
4433
4434 return 0;
4435}
4436#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4437
4438#ifndef CONFIG_ODD_RT_SIGACTION
4439/**
4440 * sys_rt_sigaction - alter an action taken by a process
4441 * @sig: signal to be sent
4442 * @act: new sigaction
4443 * @oact: used to save the previous sigaction
4444 * @sigsetsize: size of sigset_t type
4445 */
4446SYSCALL_DEFINE4(rt_sigaction, int, sig,
4447 const struct sigaction __user *, act,
4448 struct sigaction __user *, oact,
4449 size_t, sigsetsize)
4450{
4451 struct k_sigaction new_sa, old_sa;
4452 int ret;
4453
4454 /* XXX: Don't preclude handling different sized sigset_t's. */
4455 if (sigsetsize != sizeof(sigset_t))
4456 return -EINVAL;
4457
4458 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4459 return -EFAULT;
4460
4461 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4462 if (ret)
4463 return ret;
4464
4465 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4466 return -EFAULT;
4467
4468 return 0;
4469}
4470#ifdef CONFIG_COMPAT
4471COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4472 const struct compat_sigaction __user *, act,
4473 struct compat_sigaction __user *, oact,
4474 compat_size_t, sigsetsize)
4475{
4476 struct k_sigaction new_ka, old_ka;
4477#ifdef __ARCH_HAS_SA_RESTORER
4478 compat_uptr_t restorer;
4479#endif
4480 int ret;
4481
4482 /* XXX: Don't preclude handling different sized sigset_t's. */
4483 if (sigsetsize != sizeof(compat_sigset_t))
4484 return -EINVAL;
4485
4486 if (act) {
4487 compat_uptr_t handler;
4488 ret = get_user(handler, &act->sa_handler);
4489 new_ka.sa.sa_handler = compat_ptr(handler);
4490#ifdef __ARCH_HAS_SA_RESTORER
4491 ret |= get_user(restorer, &act->sa_restorer);
4492 new_ka.sa.sa_restorer = compat_ptr(restorer);
4493#endif
4494 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4495 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4496 if (ret)
4497 return -EFAULT;
4498 }
4499
4500 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4501 if (!ret && oact) {
4502 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4503 &oact->sa_handler);
4504 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4505 sizeof(oact->sa_mask));
4506 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4507#ifdef __ARCH_HAS_SA_RESTORER
4508 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4509 &oact->sa_restorer);
4510#endif
4511 }
4512 return ret;
4513}
4514#endif
4515#endif /* !CONFIG_ODD_RT_SIGACTION */
4516
4517#ifdef CONFIG_OLD_SIGACTION
4518SYSCALL_DEFINE3(sigaction, int, sig,
4519 const struct old_sigaction __user *, act,
4520 struct old_sigaction __user *, oact)
4521{
4522 struct k_sigaction new_ka, old_ka;
4523 int ret;
4524
4525 if (act) {
4526 old_sigset_t mask;
4527 if (!access_ok(act, sizeof(*act)) ||
4528 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4529 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4530 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4531 __get_user(mask, &act->sa_mask))
4532 return -EFAULT;
4533#ifdef __ARCH_HAS_KA_RESTORER
4534 new_ka.ka_restorer = NULL;
4535#endif
4536 siginitset(&new_ka.sa.sa_mask, mask);
4537 }
4538
4539 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4540
4541 if (!ret && oact) {
4542 if (!access_ok(oact, sizeof(*oact)) ||
4543 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4544 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4545 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4546 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4547 return -EFAULT;
4548 }
4549
4550 return ret;
4551}
4552#endif
4553#ifdef CONFIG_COMPAT_OLD_SIGACTION
4554COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4555 const struct compat_old_sigaction __user *, act,
4556 struct compat_old_sigaction __user *, oact)
4557{
4558 struct k_sigaction new_ka, old_ka;
4559 int ret;
4560 compat_old_sigset_t mask;
4561 compat_uptr_t handler, restorer;
4562
4563 if (act) {
4564 if (!access_ok(act, sizeof(*act)) ||
4565 __get_user(handler, &act->sa_handler) ||
4566 __get_user(restorer, &act->sa_restorer) ||
4567 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4568 __get_user(mask, &act->sa_mask))
4569 return -EFAULT;
4570
4571#ifdef __ARCH_HAS_KA_RESTORER
4572 new_ka.ka_restorer = NULL;
4573#endif
4574 new_ka.sa.sa_handler = compat_ptr(handler);
4575 new_ka.sa.sa_restorer = compat_ptr(restorer);
4576 siginitset(&new_ka.sa.sa_mask, mask);
4577 }
4578
4579 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4580
4581 if (!ret && oact) {
4582 if (!access_ok(oact, sizeof(*oact)) ||
4583 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4584 &oact->sa_handler) ||
4585 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4586 &oact->sa_restorer) ||
4587 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4588 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4589 return -EFAULT;
4590 }
4591 return ret;
4592}
4593#endif
4594
4595#ifdef CONFIG_SGETMASK_SYSCALL
4596
4597/*
4598 * For backwards compatibility. Functionality superseded by sigprocmask.
4599 */
4600SYSCALL_DEFINE0(sgetmask)
4601{
4602 /* SMP safe */
4603 return current->blocked.sig[0];
4604}
4605
4606SYSCALL_DEFINE1(ssetmask, int, newmask)
4607{
4608 int old = current->blocked.sig[0];
4609 sigset_t newset;
4610
4611 siginitset(&newset, newmask);
4612 set_current_blocked(&newset);
4613
4614 return old;
4615}
4616#endif /* CONFIG_SGETMASK_SYSCALL */
4617
4618#ifdef __ARCH_WANT_SYS_SIGNAL
4619/*
4620 * For backwards compatibility. Functionality superseded by sigaction.
4621 */
4622SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4623{
4624 struct k_sigaction new_sa, old_sa;
4625 int ret;
4626
4627 new_sa.sa.sa_handler = handler;
4628 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4629 sigemptyset(&new_sa.sa.sa_mask);
4630
4631 ret = do_sigaction(sig, &new_sa, &old_sa);
4632
4633 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4634}
4635#endif /* __ARCH_WANT_SYS_SIGNAL */
4636
4637#ifdef __ARCH_WANT_SYS_PAUSE
4638
4639SYSCALL_DEFINE0(pause)
4640{
4641 while (!signal_pending(current)) {
4642 __set_current_state(TASK_INTERRUPTIBLE);
4643 schedule();
4644 }
4645 return -ERESTARTNOHAND;
4646}
4647
4648#endif
4649
4650static int sigsuspend(sigset_t *set)
4651{
4652 current->saved_sigmask = current->blocked;
4653 set_current_blocked(set);
4654
4655 while (!signal_pending(current)) {
4656 __set_current_state(TASK_INTERRUPTIBLE);
4657 schedule();
4658 }
4659 set_restore_sigmask();
4660 return -ERESTARTNOHAND;
4661}
4662
4663/**
4664 * sys_rt_sigsuspend - replace the signal mask for a value with the
4665 * @unewset value until a signal is received
4666 * @unewset: new signal mask value
4667 * @sigsetsize: size of sigset_t type
4668 */
4669SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4670{
4671 sigset_t newset;
4672
4673 /* XXX: Don't preclude handling different sized sigset_t's. */
4674 if (sigsetsize != sizeof(sigset_t))
4675 return -EINVAL;
4676
4677 if (copy_from_user(&newset, unewset, sizeof(newset)))
4678 return -EFAULT;
4679 return sigsuspend(&newset);
4680}
4681
4682#ifdef CONFIG_COMPAT
4683COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4684{
4685 sigset_t newset;
4686
4687 /* XXX: Don't preclude handling different sized sigset_t's. */
4688 if (sigsetsize != sizeof(sigset_t))
4689 return -EINVAL;
4690
4691 if (get_compat_sigset(&newset, unewset))
4692 return -EFAULT;
4693 return sigsuspend(&newset);
4694}
4695#endif
4696
4697#ifdef CONFIG_OLD_SIGSUSPEND
4698SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4699{
4700 sigset_t blocked;
4701 siginitset(&blocked, mask);
4702 return sigsuspend(&blocked);
4703}
4704#endif
4705#ifdef CONFIG_OLD_SIGSUSPEND3
4706SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4707{
4708 sigset_t blocked;
4709 siginitset(&blocked, mask);
4710 return sigsuspend(&blocked);
4711}
4712#endif
4713
4714__weak const char *arch_vma_name(struct vm_area_struct *vma)
4715{
4716 return NULL;
4717}
4718
4719static inline void siginfo_buildtime_checks(void)
4720{
4721 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4722
4723 /* Verify the offsets in the two siginfos match */
4724#define CHECK_OFFSET(field) \
4725 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4726
4727 /* kill */
4728 CHECK_OFFSET(si_pid);
4729 CHECK_OFFSET(si_uid);
4730
4731 /* timer */
4732 CHECK_OFFSET(si_tid);
4733 CHECK_OFFSET(si_overrun);
4734 CHECK_OFFSET(si_value);
4735
4736 /* rt */
4737 CHECK_OFFSET(si_pid);
4738 CHECK_OFFSET(si_uid);
4739 CHECK_OFFSET(si_value);
4740
4741 /* sigchld */
4742 CHECK_OFFSET(si_pid);
4743 CHECK_OFFSET(si_uid);
4744 CHECK_OFFSET(si_status);
4745 CHECK_OFFSET(si_utime);
4746 CHECK_OFFSET(si_stime);
4747
4748 /* sigfault */
4749 CHECK_OFFSET(si_addr);
4750 CHECK_OFFSET(si_trapno);
4751 CHECK_OFFSET(si_addr_lsb);
4752 CHECK_OFFSET(si_lower);
4753 CHECK_OFFSET(si_upper);
4754 CHECK_OFFSET(si_pkey);
4755 CHECK_OFFSET(si_perf_data);
4756 CHECK_OFFSET(si_perf_type);
4757 CHECK_OFFSET(si_perf_flags);
4758
4759 /* sigpoll */
4760 CHECK_OFFSET(si_band);
4761 CHECK_OFFSET(si_fd);
4762
4763 /* sigsys */
4764 CHECK_OFFSET(si_call_addr);
4765 CHECK_OFFSET(si_syscall);
4766 CHECK_OFFSET(si_arch);
4767#undef CHECK_OFFSET
4768
4769 /* usb asyncio */
4770 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4771 offsetof(struct siginfo, si_addr));
4772 if (sizeof(int) == sizeof(void __user *)) {
4773 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4774 sizeof(void __user *));
4775 } else {
4776 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4777 sizeof_field(struct siginfo, si_uid)) !=
4778 sizeof(void __user *));
4779 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4780 offsetof(struct siginfo, si_uid));
4781 }
4782#ifdef CONFIG_COMPAT
4783 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4784 offsetof(struct compat_siginfo, si_addr));
4785 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4786 sizeof(compat_uptr_t));
4787 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4788 sizeof_field(struct siginfo, si_pid));
4789#endif
4790}
4791
4792#if defined(CONFIG_SYSCTL)
4793static struct ctl_table signal_debug_table[] = {
4794#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4795 {
4796 .procname = "exception-trace",
4797 .data = &show_unhandled_signals,
4798 .maxlen = sizeof(int),
4799 .mode = 0644,
4800 .proc_handler = proc_dointvec
4801 },
4802#endif
4803 { }
4804};
4805
4806static int __init init_signal_sysctls(void)
4807{
4808 register_sysctl_init("debug", signal_debug_table);
4809 return 0;
4810}
4811early_initcall(init_signal_sysctls);
4812#endif /* CONFIG_SYSCTL */
4813
4814void __init signals_init(void)
4815{
4816 siginfo_buildtime_checks();
4817
4818 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4819}
4820
4821#ifdef CONFIG_KGDB_KDB
4822#include <linux/kdb.h>
4823/*
4824 * kdb_send_sig - Allows kdb to send signals without exposing
4825 * signal internals. This function checks if the required locks are
4826 * available before calling the main signal code, to avoid kdb
4827 * deadlocks.
4828 */
4829void kdb_send_sig(struct task_struct *t, int sig)
4830{
4831 static struct task_struct *kdb_prev_t;
4832 int new_t, ret;
4833 if (!spin_trylock(&t->sighand->siglock)) {
4834 kdb_printf("Can't do kill command now.\n"
4835 "The sigmask lock is held somewhere else in "
4836 "kernel, try again later\n");
4837 return;
4838 }
4839 new_t = kdb_prev_t != t;
4840 kdb_prev_t = t;
4841 if (!task_is_running(t) && new_t) {
4842 spin_unlock(&t->sighand->siglock);
4843 kdb_printf("Process is not RUNNING, sending a signal from "
4844 "kdb risks deadlock\n"
4845 "on the run queue locks. "
4846 "The signal has _not_ been sent.\n"
4847 "Reissue the kill command if you want to risk "
4848 "the deadlock.\n");
4849 return;
4850 }
4851 ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4852 spin_unlock(&t->sighand->siglock);
4853 if (ret)
4854 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4855 sig, t->pid);
4856 else
4857 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4858}
4859#endif /* CONFIG_KGDB_KDB */
1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/sched/mm.h>
17#include <linux/sched/user.h>
18#include <linux/sched/debug.h>
19#include <linux/sched/task.h>
20#include <linux/sched/task_stack.h>
21#include <linux/sched/cputime.h>
22#include <linux/fs.h>
23#include <linux/tty.h>
24#include <linux/binfmts.h>
25#include <linux/coredump.h>
26#include <linux/security.h>
27#include <linux/syscalls.h>
28#include <linux/ptrace.h>
29#include <linux/signal.h>
30#include <linux/signalfd.h>
31#include <linux/ratelimit.h>
32#include <linux/tracehook.h>
33#include <linux/capability.h>
34#include <linux/freezer.h>
35#include <linux/pid_namespace.h>
36#include <linux/nsproxy.h>
37#include <linux/user_namespace.h>
38#include <linux/uprobes.h>
39#include <linux/compat.h>
40#include <linux/cn_proc.h>
41#include <linux/compiler.h>
42#include <linux/posix-timers.h>
43#include <linux/livepatch.h>
44
45#define CREATE_TRACE_POINTS
46#include <trace/events/signal.h>
47
48#include <asm/param.h>
49#include <linux/uaccess.h>
50#include <asm/unistd.h>
51#include <asm/siginfo.h>
52#include <asm/cacheflush.h>
53#include "audit.h" /* audit_signal_info() */
54
55/*
56 * SLAB caches for signal bits.
57 */
58
59static struct kmem_cache *sigqueue_cachep;
60
61int print_fatal_signals __read_mostly;
62
63static void __user *sig_handler(struct task_struct *t, int sig)
64{
65 return t->sighand->action[sig - 1].sa.sa_handler;
66}
67
68static int sig_handler_ignored(void __user *handler, int sig)
69{
70 /* Is it explicitly or implicitly ignored? */
71 return handler == SIG_IGN ||
72 (handler == SIG_DFL && sig_kernel_ignore(sig));
73}
74
75static int sig_task_ignored(struct task_struct *t, int sig, bool force)
76{
77 void __user *handler;
78
79 handler = sig_handler(t, sig);
80
81 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
82 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
83 return 1;
84
85 return sig_handler_ignored(handler, sig);
86}
87
88static int sig_ignored(struct task_struct *t, int sig, bool force)
89{
90 /*
91 * Blocked signals are never ignored, since the
92 * signal handler may change by the time it is
93 * unblocked.
94 */
95 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
96 return 0;
97
98 /*
99 * Tracers may want to know about even ignored signal unless it
100 * is SIGKILL which can't be reported anyway but can be ignored
101 * by SIGNAL_UNKILLABLE task.
102 */
103 if (t->ptrace && sig != SIGKILL)
104 return 0;
105
106 return sig_task_ignored(t, sig, force);
107}
108
109/*
110 * Re-calculate pending state from the set of locally pending
111 * signals, globally pending signals, and blocked signals.
112 */
113static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
114{
115 unsigned long ready;
116 long i;
117
118 switch (_NSIG_WORDS) {
119 default:
120 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
121 ready |= signal->sig[i] &~ blocked->sig[i];
122 break;
123
124 case 4: ready = signal->sig[3] &~ blocked->sig[3];
125 ready |= signal->sig[2] &~ blocked->sig[2];
126 ready |= signal->sig[1] &~ blocked->sig[1];
127 ready |= signal->sig[0] &~ blocked->sig[0];
128 break;
129
130 case 2: ready = signal->sig[1] &~ blocked->sig[1];
131 ready |= signal->sig[0] &~ blocked->sig[0];
132 break;
133
134 case 1: ready = signal->sig[0] &~ blocked->sig[0];
135 }
136 return ready != 0;
137}
138
139#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
140
141static int recalc_sigpending_tsk(struct task_struct *t)
142{
143 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
144 PENDING(&t->pending, &t->blocked) ||
145 PENDING(&t->signal->shared_pending, &t->blocked)) {
146 set_tsk_thread_flag(t, TIF_SIGPENDING);
147 return 1;
148 }
149 /*
150 * We must never clear the flag in another thread, or in current
151 * when it's possible the current syscall is returning -ERESTART*.
152 * So we don't clear it here, and only callers who know they should do.
153 */
154 return 0;
155}
156
157/*
158 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
159 * This is superfluous when called on current, the wakeup is a harmless no-op.
160 */
161void recalc_sigpending_and_wake(struct task_struct *t)
162{
163 if (recalc_sigpending_tsk(t))
164 signal_wake_up(t, 0);
165}
166
167void recalc_sigpending(void)
168{
169 if (!recalc_sigpending_tsk(current) && !freezing(current) &&
170 !klp_patch_pending(current))
171 clear_thread_flag(TIF_SIGPENDING);
172
173}
174
175/* Given the mask, find the first available signal that should be serviced. */
176
177#define SYNCHRONOUS_MASK \
178 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
179 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
180
181int next_signal(struct sigpending *pending, sigset_t *mask)
182{
183 unsigned long i, *s, *m, x;
184 int sig = 0;
185
186 s = pending->signal.sig;
187 m = mask->sig;
188
189 /*
190 * Handle the first word specially: it contains the
191 * synchronous signals that need to be dequeued first.
192 */
193 x = *s &~ *m;
194 if (x) {
195 if (x & SYNCHRONOUS_MASK)
196 x &= SYNCHRONOUS_MASK;
197 sig = ffz(~x) + 1;
198 return sig;
199 }
200
201 switch (_NSIG_WORDS) {
202 default:
203 for (i = 1; i < _NSIG_WORDS; ++i) {
204 x = *++s &~ *++m;
205 if (!x)
206 continue;
207 sig = ffz(~x) + i*_NSIG_BPW + 1;
208 break;
209 }
210 break;
211
212 case 2:
213 x = s[1] &~ m[1];
214 if (!x)
215 break;
216 sig = ffz(~x) + _NSIG_BPW + 1;
217 break;
218
219 case 1:
220 /* Nothing to do */
221 break;
222 }
223
224 return sig;
225}
226
227static inline void print_dropped_signal(int sig)
228{
229 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
230
231 if (!print_fatal_signals)
232 return;
233
234 if (!__ratelimit(&ratelimit_state))
235 return;
236
237 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
238 current->comm, current->pid, sig);
239}
240
241/**
242 * task_set_jobctl_pending - set jobctl pending bits
243 * @task: target task
244 * @mask: pending bits to set
245 *
246 * Clear @mask from @task->jobctl. @mask must be subset of
247 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
248 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
249 * cleared. If @task is already being killed or exiting, this function
250 * becomes noop.
251 *
252 * CONTEXT:
253 * Must be called with @task->sighand->siglock held.
254 *
255 * RETURNS:
256 * %true if @mask is set, %false if made noop because @task was dying.
257 */
258bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
259{
260 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
261 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
262 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
263
264 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
265 return false;
266
267 if (mask & JOBCTL_STOP_SIGMASK)
268 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
269
270 task->jobctl |= mask;
271 return true;
272}
273
274/**
275 * task_clear_jobctl_trapping - clear jobctl trapping bit
276 * @task: target task
277 *
278 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
279 * Clear it and wake up the ptracer. Note that we don't need any further
280 * locking. @task->siglock guarantees that @task->parent points to the
281 * ptracer.
282 *
283 * CONTEXT:
284 * Must be called with @task->sighand->siglock held.
285 */
286void task_clear_jobctl_trapping(struct task_struct *task)
287{
288 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
289 task->jobctl &= ~JOBCTL_TRAPPING;
290 smp_mb(); /* advised by wake_up_bit() */
291 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
292 }
293}
294
295/**
296 * task_clear_jobctl_pending - clear jobctl pending bits
297 * @task: target task
298 * @mask: pending bits to clear
299 *
300 * Clear @mask from @task->jobctl. @mask must be subset of
301 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
302 * STOP bits are cleared together.
303 *
304 * If clearing of @mask leaves no stop or trap pending, this function calls
305 * task_clear_jobctl_trapping().
306 *
307 * CONTEXT:
308 * Must be called with @task->sighand->siglock held.
309 */
310void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
311{
312 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
313
314 if (mask & JOBCTL_STOP_PENDING)
315 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
316
317 task->jobctl &= ~mask;
318
319 if (!(task->jobctl & JOBCTL_PENDING_MASK))
320 task_clear_jobctl_trapping(task);
321}
322
323/**
324 * task_participate_group_stop - participate in a group stop
325 * @task: task participating in a group stop
326 *
327 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
328 * Group stop states are cleared and the group stop count is consumed if
329 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
330 * stop, the appropriate %SIGNAL_* flags are set.
331 *
332 * CONTEXT:
333 * Must be called with @task->sighand->siglock held.
334 *
335 * RETURNS:
336 * %true if group stop completion should be notified to the parent, %false
337 * otherwise.
338 */
339static bool task_participate_group_stop(struct task_struct *task)
340{
341 struct signal_struct *sig = task->signal;
342 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
343
344 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
345
346 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
347
348 if (!consume)
349 return false;
350
351 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
352 sig->group_stop_count--;
353
354 /*
355 * Tell the caller to notify completion iff we are entering into a
356 * fresh group stop. Read comment in do_signal_stop() for details.
357 */
358 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
359 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
360 return true;
361 }
362 return false;
363}
364
365/*
366 * allocate a new signal queue record
367 * - this may be called without locks if and only if t == current, otherwise an
368 * appropriate lock must be held to stop the target task from exiting
369 */
370static struct sigqueue *
371__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
372{
373 struct sigqueue *q = NULL;
374 struct user_struct *user;
375
376 /*
377 * Protect access to @t credentials. This can go away when all
378 * callers hold rcu read lock.
379 */
380 rcu_read_lock();
381 user = get_uid(__task_cred(t)->user);
382 atomic_inc(&user->sigpending);
383 rcu_read_unlock();
384
385 if (override_rlimit ||
386 atomic_read(&user->sigpending) <=
387 task_rlimit(t, RLIMIT_SIGPENDING)) {
388 q = kmem_cache_alloc(sigqueue_cachep, flags);
389 } else {
390 print_dropped_signal(sig);
391 }
392
393 if (unlikely(q == NULL)) {
394 atomic_dec(&user->sigpending);
395 free_uid(user);
396 } else {
397 INIT_LIST_HEAD(&q->list);
398 q->flags = 0;
399 q->user = user;
400 }
401
402 return q;
403}
404
405static void __sigqueue_free(struct sigqueue *q)
406{
407 if (q->flags & SIGQUEUE_PREALLOC)
408 return;
409 atomic_dec(&q->user->sigpending);
410 free_uid(q->user);
411 kmem_cache_free(sigqueue_cachep, q);
412}
413
414void flush_sigqueue(struct sigpending *queue)
415{
416 struct sigqueue *q;
417
418 sigemptyset(&queue->signal);
419 while (!list_empty(&queue->list)) {
420 q = list_entry(queue->list.next, struct sigqueue , list);
421 list_del_init(&q->list);
422 __sigqueue_free(q);
423 }
424}
425
426/*
427 * Flush all pending signals for this kthread.
428 */
429void flush_signals(struct task_struct *t)
430{
431 unsigned long flags;
432
433 spin_lock_irqsave(&t->sighand->siglock, flags);
434 clear_tsk_thread_flag(t, TIF_SIGPENDING);
435 flush_sigqueue(&t->pending);
436 flush_sigqueue(&t->signal->shared_pending);
437 spin_unlock_irqrestore(&t->sighand->siglock, flags);
438}
439
440#ifdef CONFIG_POSIX_TIMERS
441static void __flush_itimer_signals(struct sigpending *pending)
442{
443 sigset_t signal, retain;
444 struct sigqueue *q, *n;
445
446 signal = pending->signal;
447 sigemptyset(&retain);
448
449 list_for_each_entry_safe(q, n, &pending->list, list) {
450 int sig = q->info.si_signo;
451
452 if (likely(q->info.si_code != SI_TIMER)) {
453 sigaddset(&retain, sig);
454 } else {
455 sigdelset(&signal, sig);
456 list_del_init(&q->list);
457 __sigqueue_free(q);
458 }
459 }
460
461 sigorsets(&pending->signal, &signal, &retain);
462}
463
464void flush_itimer_signals(void)
465{
466 struct task_struct *tsk = current;
467 unsigned long flags;
468
469 spin_lock_irqsave(&tsk->sighand->siglock, flags);
470 __flush_itimer_signals(&tsk->pending);
471 __flush_itimer_signals(&tsk->signal->shared_pending);
472 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
473}
474#endif
475
476void ignore_signals(struct task_struct *t)
477{
478 int i;
479
480 for (i = 0; i < _NSIG; ++i)
481 t->sighand->action[i].sa.sa_handler = SIG_IGN;
482
483 flush_signals(t);
484}
485
486/*
487 * Flush all handlers for a task.
488 */
489
490void
491flush_signal_handlers(struct task_struct *t, int force_default)
492{
493 int i;
494 struct k_sigaction *ka = &t->sighand->action[0];
495 for (i = _NSIG ; i != 0 ; i--) {
496 if (force_default || ka->sa.sa_handler != SIG_IGN)
497 ka->sa.sa_handler = SIG_DFL;
498 ka->sa.sa_flags = 0;
499#ifdef __ARCH_HAS_SA_RESTORER
500 ka->sa.sa_restorer = NULL;
501#endif
502 sigemptyset(&ka->sa.sa_mask);
503 ka++;
504 }
505}
506
507int unhandled_signal(struct task_struct *tsk, int sig)
508{
509 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
510 if (is_global_init(tsk))
511 return 1;
512 if (handler != SIG_IGN && handler != SIG_DFL)
513 return 0;
514 /* if ptraced, let the tracer determine */
515 return !tsk->ptrace;
516}
517
518static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
519 bool *resched_timer)
520{
521 struct sigqueue *q, *first = NULL;
522
523 /*
524 * Collect the siginfo appropriate to this signal. Check if
525 * there is another siginfo for the same signal.
526 */
527 list_for_each_entry(q, &list->list, list) {
528 if (q->info.si_signo == sig) {
529 if (first)
530 goto still_pending;
531 first = q;
532 }
533 }
534
535 sigdelset(&list->signal, sig);
536
537 if (first) {
538still_pending:
539 list_del_init(&first->list);
540 copy_siginfo(info, &first->info);
541
542 *resched_timer =
543 (first->flags & SIGQUEUE_PREALLOC) &&
544 (info->si_code == SI_TIMER) &&
545 (info->si_sys_private);
546
547 __sigqueue_free(first);
548 } else {
549 /*
550 * Ok, it wasn't in the queue. This must be
551 * a fast-pathed signal or we must have been
552 * out of queue space. So zero out the info.
553 */
554 clear_siginfo(info);
555 info->si_signo = sig;
556 info->si_errno = 0;
557 info->si_code = SI_USER;
558 info->si_pid = 0;
559 info->si_uid = 0;
560 }
561}
562
563static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
564 siginfo_t *info, bool *resched_timer)
565{
566 int sig = next_signal(pending, mask);
567
568 if (sig)
569 collect_signal(sig, pending, info, resched_timer);
570 return sig;
571}
572
573/*
574 * Dequeue a signal and return the element to the caller, which is
575 * expected to free it.
576 *
577 * All callers have to hold the siglock.
578 */
579int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
580{
581 bool resched_timer = false;
582 int signr;
583
584 /* We only dequeue private signals from ourselves, we don't let
585 * signalfd steal them
586 */
587 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
588 if (!signr) {
589 signr = __dequeue_signal(&tsk->signal->shared_pending,
590 mask, info, &resched_timer);
591#ifdef CONFIG_POSIX_TIMERS
592 /*
593 * itimer signal ?
594 *
595 * itimers are process shared and we restart periodic
596 * itimers in the signal delivery path to prevent DoS
597 * attacks in the high resolution timer case. This is
598 * compliant with the old way of self-restarting
599 * itimers, as the SIGALRM is a legacy signal and only
600 * queued once. Changing the restart behaviour to
601 * restart the timer in the signal dequeue path is
602 * reducing the timer noise on heavy loaded !highres
603 * systems too.
604 */
605 if (unlikely(signr == SIGALRM)) {
606 struct hrtimer *tmr = &tsk->signal->real_timer;
607
608 if (!hrtimer_is_queued(tmr) &&
609 tsk->signal->it_real_incr != 0) {
610 hrtimer_forward(tmr, tmr->base->get_time(),
611 tsk->signal->it_real_incr);
612 hrtimer_restart(tmr);
613 }
614 }
615#endif
616 }
617
618 recalc_sigpending();
619 if (!signr)
620 return 0;
621
622 if (unlikely(sig_kernel_stop(signr))) {
623 /*
624 * Set a marker that we have dequeued a stop signal. Our
625 * caller might release the siglock and then the pending
626 * stop signal it is about to process is no longer in the
627 * pending bitmasks, but must still be cleared by a SIGCONT
628 * (and overruled by a SIGKILL). So those cases clear this
629 * shared flag after we've set it. Note that this flag may
630 * remain set after the signal we return is ignored or
631 * handled. That doesn't matter because its only purpose
632 * is to alert stop-signal processing code when another
633 * processor has come along and cleared the flag.
634 */
635 current->jobctl |= JOBCTL_STOP_DEQUEUED;
636 }
637#ifdef CONFIG_POSIX_TIMERS
638 if (resched_timer) {
639 /*
640 * Release the siglock to ensure proper locking order
641 * of timer locks outside of siglocks. Note, we leave
642 * irqs disabled here, since the posix-timers code is
643 * about to disable them again anyway.
644 */
645 spin_unlock(&tsk->sighand->siglock);
646 posixtimer_rearm(info);
647 spin_lock(&tsk->sighand->siglock);
648
649 /* Don't expose the si_sys_private value to userspace */
650 info->si_sys_private = 0;
651 }
652#endif
653 return signr;
654}
655
656/*
657 * Tell a process that it has a new active signal..
658 *
659 * NOTE! we rely on the previous spin_lock to
660 * lock interrupts for us! We can only be called with
661 * "siglock" held, and the local interrupt must
662 * have been disabled when that got acquired!
663 *
664 * No need to set need_resched since signal event passing
665 * goes through ->blocked
666 */
667void signal_wake_up_state(struct task_struct *t, unsigned int state)
668{
669 set_tsk_thread_flag(t, TIF_SIGPENDING);
670 /*
671 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
672 * case. We don't check t->state here because there is a race with it
673 * executing another processor and just now entering stopped state.
674 * By using wake_up_state, we ensure the process will wake up and
675 * handle its death signal.
676 */
677 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
678 kick_process(t);
679}
680
681/*
682 * Remove signals in mask from the pending set and queue.
683 * Returns 1 if any signals were found.
684 *
685 * All callers must be holding the siglock.
686 */
687static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
688{
689 struct sigqueue *q, *n;
690 sigset_t m;
691
692 sigandsets(&m, mask, &s->signal);
693 if (sigisemptyset(&m))
694 return 0;
695
696 sigandnsets(&s->signal, &s->signal, mask);
697 list_for_each_entry_safe(q, n, &s->list, list) {
698 if (sigismember(mask, q->info.si_signo)) {
699 list_del_init(&q->list);
700 __sigqueue_free(q);
701 }
702 }
703 return 1;
704}
705
706static inline int is_si_special(const struct siginfo *info)
707{
708 return info <= SEND_SIG_FORCED;
709}
710
711static inline bool si_fromuser(const struct siginfo *info)
712{
713 return info == SEND_SIG_NOINFO ||
714 (!is_si_special(info) && SI_FROMUSER(info));
715}
716
717/*
718 * called with RCU read lock from check_kill_permission()
719 */
720static int kill_ok_by_cred(struct task_struct *t)
721{
722 const struct cred *cred = current_cred();
723 const struct cred *tcred = __task_cred(t);
724
725 if (uid_eq(cred->euid, tcred->suid) ||
726 uid_eq(cred->euid, tcred->uid) ||
727 uid_eq(cred->uid, tcred->suid) ||
728 uid_eq(cred->uid, tcred->uid))
729 return 1;
730
731 if (ns_capable(tcred->user_ns, CAP_KILL))
732 return 1;
733
734 return 0;
735}
736
737/*
738 * Bad permissions for sending the signal
739 * - the caller must hold the RCU read lock
740 */
741static int check_kill_permission(int sig, struct siginfo *info,
742 struct task_struct *t)
743{
744 struct pid *sid;
745 int error;
746
747 if (!valid_signal(sig))
748 return -EINVAL;
749
750 if (!si_fromuser(info))
751 return 0;
752
753 error = audit_signal_info(sig, t); /* Let audit system see the signal */
754 if (error)
755 return error;
756
757 if (!same_thread_group(current, t) &&
758 !kill_ok_by_cred(t)) {
759 switch (sig) {
760 case SIGCONT:
761 sid = task_session(t);
762 /*
763 * We don't return the error if sid == NULL. The
764 * task was unhashed, the caller must notice this.
765 */
766 if (!sid || sid == task_session(current))
767 break;
768 default:
769 return -EPERM;
770 }
771 }
772
773 return security_task_kill(t, info, sig, NULL);
774}
775
776/**
777 * ptrace_trap_notify - schedule trap to notify ptracer
778 * @t: tracee wanting to notify tracer
779 *
780 * This function schedules sticky ptrace trap which is cleared on the next
781 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
782 * ptracer.
783 *
784 * If @t is running, STOP trap will be taken. If trapped for STOP and
785 * ptracer is listening for events, tracee is woken up so that it can
786 * re-trap for the new event. If trapped otherwise, STOP trap will be
787 * eventually taken without returning to userland after the existing traps
788 * are finished by PTRACE_CONT.
789 *
790 * CONTEXT:
791 * Must be called with @task->sighand->siglock held.
792 */
793static void ptrace_trap_notify(struct task_struct *t)
794{
795 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
796 assert_spin_locked(&t->sighand->siglock);
797
798 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
799 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
800}
801
802/*
803 * Handle magic process-wide effects of stop/continue signals. Unlike
804 * the signal actions, these happen immediately at signal-generation
805 * time regardless of blocking, ignoring, or handling. This does the
806 * actual continuing for SIGCONT, but not the actual stopping for stop
807 * signals. The process stop is done as a signal action for SIG_DFL.
808 *
809 * Returns true if the signal should be actually delivered, otherwise
810 * it should be dropped.
811 */
812static bool prepare_signal(int sig, struct task_struct *p, bool force)
813{
814 struct signal_struct *signal = p->signal;
815 struct task_struct *t;
816 sigset_t flush;
817
818 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
819 if (!(signal->flags & SIGNAL_GROUP_EXIT))
820 return sig == SIGKILL;
821 /*
822 * The process is in the middle of dying, nothing to do.
823 */
824 } else if (sig_kernel_stop(sig)) {
825 /*
826 * This is a stop signal. Remove SIGCONT from all queues.
827 */
828 siginitset(&flush, sigmask(SIGCONT));
829 flush_sigqueue_mask(&flush, &signal->shared_pending);
830 for_each_thread(p, t)
831 flush_sigqueue_mask(&flush, &t->pending);
832 } else if (sig == SIGCONT) {
833 unsigned int why;
834 /*
835 * Remove all stop signals from all queues, wake all threads.
836 */
837 siginitset(&flush, SIG_KERNEL_STOP_MASK);
838 flush_sigqueue_mask(&flush, &signal->shared_pending);
839 for_each_thread(p, t) {
840 flush_sigqueue_mask(&flush, &t->pending);
841 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
842 if (likely(!(t->ptrace & PT_SEIZED)))
843 wake_up_state(t, __TASK_STOPPED);
844 else
845 ptrace_trap_notify(t);
846 }
847
848 /*
849 * Notify the parent with CLD_CONTINUED if we were stopped.
850 *
851 * If we were in the middle of a group stop, we pretend it
852 * was already finished, and then continued. Since SIGCHLD
853 * doesn't queue we report only CLD_STOPPED, as if the next
854 * CLD_CONTINUED was dropped.
855 */
856 why = 0;
857 if (signal->flags & SIGNAL_STOP_STOPPED)
858 why |= SIGNAL_CLD_CONTINUED;
859 else if (signal->group_stop_count)
860 why |= SIGNAL_CLD_STOPPED;
861
862 if (why) {
863 /*
864 * The first thread which returns from do_signal_stop()
865 * will take ->siglock, notice SIGNAL_CLD_MASK, and
866 * notify its parent. See get_signal_to_deliver().
867 */
868 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
869 signal->group_stop_count = 0;
870 signal->group_exit_code = 0;
871 }
872 }
873
874 return !sig_ignored(p, sig, force);
875}
876
877/*
878 * Test if P wants to take SIG. After we've checked all threads with this,
879 * it's equivalent to finding no threads not blocking SIG. Any threads not
880 * blocking SIG were ruled out because they are not running and already
881 * have pending signals. Such threads will dequeue from the shared queue
882 * as soon as they're available, so putting the signal on the shared queue
883 * will be equivalent to sending it to one such thread.
884 */
885static inline int wants_signal(int sig, struct task_struct *p)
886{
887 if (sigismember(&p->blocked, sig))
888 return 0;
889 if (p->flags & PF_EXITING)
890 return 0;
891 if (sig == SIGKILL)
892 return 1;
893 if (task_is_stopped_or_traced(p))
894 return 0;
895 return task_curr(p) || !signal_pending(p);
896}
897
898static void complete_signal(int sig, struct task_struct *p, int group)
899{
900 struct signal_struct *signal = p->signal;
901 struct task_struct *t;
902
903 /*
904 * Now find a thread we can wake up to take the signal off the queue.
905 *
906 * If the main thread wants the signal, it gets first crack.
907 * Probably the least surprising to the average bear.
908 */
909 if (wants_signal(sig, p))
910 t = p;
911 else if (!group || thread_group_empty(p))
912 /*
913 * There is just one thread and it does not need to be woken.
914 * It will dequeue unblocked signals before it runs again.
915 */
916 return;
917 else {
918 /*
919 * Otherwise try to find a suitable thread.
920 */
921 t = signal->curr_target;
922 while (!wants_signal(sig, t)) {
923 t = next_thread(t);
924 if (t == signal->curr_target)
925 /*
926 * No thread needs to be woken.
927 * Any eligible threads will see
928 * the signal in the queue soon.
929 */
930 return;
931 }
932 signal->curr_target = t;
933 }
934
935 /*
936 * Found a killable thread. If the signal will be fatal,
937 * then start taking the whole group down immediately.
938 */
939 if (sig_fatal(p, sig) &&
940 !(signal->flags & SIGNAL_GROUP_EXIT) &&
941 !sigismember(&t->real_blocked, sig) &&
942 (sig == SIGKILL || !p->ptrace)) {
943 /*
944 * This signal will be fatal to the whole group.
945 */
946 if (!sig_kernel_coredump(sig)) {
947 /*
948 * Start a group exit and wake everybody up.
949 * This way we don't have other threads
950 * running and doing things after a slower
951 * thread has the fatal signal pending.
952 */
953 signal->flags = SIGNAL_GROUP_EXIT;
954 signal->group_exit_code = sig;
955 signal->group_stop_count = 0;
956 t = p;
957 do {
958 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
959 sigaddset(&t->pending.signal, SIGKILL);
960 signal_wake_up(t, 1);
961 } while_each_thread(p, t);
962 return;
963 }
964 }
965
966 /*
967 * The signal is already in the shared-pending queue.
968 * Tell the chosen thread to wake up and dequeue it.
969 */
970 signal_wake_up(t, sig == SIGKILL);
971 return;
972}
973
974static inline int legacy_queue(struct sigpending *signals, int sig)
975{
976 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
977}
978
979#ifdef CONFIG_USER_NS
980static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
981{
982 if (current_user_ns() == task_cred_xxx(t, user_ns))
983 return;
984
985 if (SI_FROMKERNEL(info))
986 return;
987
988 rcu_read_lock();
989 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
990 make_kuid(current_user_ns(), info->si_uid));
991 rcu_read_unlock();
992}
993#else
994static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
995{
996 return;
997}
998#endif
999
1000static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1001 int group, int from_ancestor_ns)
1002{
1003 struct sigpending *pending;
1004 struct sigqueue *q;
1005 int override_rlimit;
1006 int ret = 0, result;
1007
1008 assert_spin_locked(&t->sighand->siglock);
1009
1010 result = TRACE_SIGNAL_IGNORED;
1011 if (!prepare_signal(sig, t,
1012 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1013 goto ret;
1014
1015 pending = group ? &t->signal->shared_pending : &t->pending;
1016 /*
1017 * Short-circuit ignored signals and support queuing
1018 * exactly one non-rt signal, so that we can get more
1019 * detailed information about the cause of the signal.
1020 */
1021 result = TRACE_SIGNAL_ALREADY_PENDING;
1022 if (legacy_queue(pending, sig))
1023 goto ret;
1024
1025 result = TRACE_SIGNAL_DELIVERED;
1026 /*
1027 * fast-pathed signals for kernel-internal things like SIGSTOP
1028 * or SIGKILL.
1029 */
1030 if (info == SEND_SIG_FORCED)
1031 goto out_set;
1032
1033 /*
1034 * Real-time signals must be queued if sent by sigqueue, or
1035 * some other real-time mechanism. It is implementation
1036 * defined whether kill() does so. We attempt to do so, on
1037 * the principle of least surprise, but since kill is not
1038 * allowed to fail with EAGAIN when low on memory we just
1039 * make sure at least one signal gets delivered and don't
1040 * pass on the info struct.
1041 */
1042 if (sig < SIGRTMIN)
1043 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1044 else
1045 override_rlimit = 0;
1046
1047 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1048 if (q) {
1049 list_add_tail(&q->list, &pending->list);
1050 switch ((unsigned long) info) {
1051 case (unsigned long) SEND_SIG_NOINFO:
1052 clear_siginfo(&q->info);
1053 q->info.si_signo = sig;
1054 q->info.si_errno = 0;
1055 q->info.si_code = SI_USER;
1056 q->info.si_pid = task_tgid_nr_ns(current,
1057 task_active_pid_ns(t));
1058 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1059 break;
1060 case (unsigned long) SEND_SIG_PRIV:
1061 clear_siginfo(&q->info);
1062 q->info.si_signo = sig;
1063 q->info.si_errno = 0;
1064 q->info.si_code = SI_KERNEL;
1065 q->info.si_pid = 0;
1066 q->info.si_uid = 0;
1067 break;
1068 default:
1069 copy_siginfo(&q->info, info);
1070 if (from_ancestor_ns)
1071 q->info.si_pid = 0;
1072 break;
1073 }
1074
1075 userns_fixup_signal_uid(&q->info, t);
1076
1077 } else if (!is_si_special(info)) {
1078 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1079 /*
1080 * Queue overflow, abort. We may abort if the
1081 * signal was rt and sent by user using something
1082 * other than kill().
1083 */
1084 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1085 ret = -EAGAIN;
1086 goto ret;
1087 } else {
1088 /*
1089 * This is a silent loss of information. We still
1090 * send the signal, but the *info bits are lost.
1091 */
1092 result = TRACE_SIGNAL_LOSE_INFO;
1093 }
1094 }
1095
1096out_set:
1097 signalfd_notify(t, sig);
1098 sigaddset(&pending->signal, sig);
1099 complete_signal(sig, t, group);
1100ret:
1101 trace_signal_generate(sig, info, t, group, result);
1102 return ret;
1103}
1104
1105static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1106 int group)
1107{
1108 int from_ancestor_ns = 0;
1109
1110#ifdef CONFIG_PID_NS
1111 from_ancestor_ns = si_fromuser(info) &&
1112 !task_pid_nr_ns(current, task_active_pid_ns(t));
1113#endif
1114
1115 return __send_signal(sig, info, t, group, from_ancestor_ns);
1116}
1117
1118static void print_fatal_signal(int signr)
1119{
1120 struct pt_regs *regs = signal_pt_regs();
1121 pr_info("potentially unexpected fatal signal %d.\n", signr);
1122
1123#if defined(__i386__) && !defined(__arch_um__)
1124 pr_info("code at %08lx: ", regs->ip);
1125 {
1126 int i;
1127 for (i = 0; i < 16; i++) {
1128 unsigned char insn;
1129
1130 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1131 break;
1132 pr_cont("%02x ", insn);
1133 }
1134 }
1135 pr_cont("\n");
1136#endif
1137 preempt_disable();
1138 show_regs(regs);
1139 preempt_enable();
1140}
1141
1142static int __init setup_print_fatal_signals(char *str)
1143{
1144 get_option (&str, &print_fatal_signals);
1145
1146 return 1;
1147}
1148
1149__setup("print-fatal-signals=", setup_print_fatal_signals);
1150
1151int
1152__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1153{
1154 return send_signal(sig, info, p, 1);
1155}
1156
1157static int
1158specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1159{
1160 return send_signal(sig, info, t, 0);
1161}
1162
1163int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1164 bool group)
1165{
1166 unsigned long flags;
1167 int ret = -ESRCH;
1168
1169 if (lock_task_sighand(p, &flags)) {
1170 ret = send_signal(sig, info, p, group);
1171 unlock_task_sighand(p, &flags);
1172 }
1173
1174 return ret;
1175}
1176
1177/*
1178 * Force a signal that the process can't ignore: if necessary
1179 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1180 *
1181 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1182 * since we do not want to have a signal handler that was blocked
1183 * be invoked when user space had explicitly blocked it.
1184 *
1185 * We don't want to have recursive SIGSEGV's etc, for example,
1186 * that is why we also clear SIGNAL_UNKILLABLE.
1187 */
1188int
1189force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1190{
1191 unsigned long int flags;
1192 int ret, blocked, ignored;
1193 struct k_sigaction *action;
1194
1195 spin_lock_irqsave(&t->sighand->siglock, flags);
1196 action = &t->sighand->action[sig-1];
1197 ignored = action->sa.sa_handler == SIG_IGN;
1198 blocked = sigismember(&t->blocked, sig);
1199 if (blocked || ignored) {
1200 action->sa.sa_handler = SIG_DFL;
1201 if (blocked) {
1202 sigdelset(&t->blocked, sig);
1203 recalc_sigpending_and_wake(t);
1204 }
1205 }
1206 /*
1207 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1208 * debugging to leave init killable.
1209 */
1210 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1211 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1212 ret = specific_send_sig_info(sig, info, t);
1213 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1214
1215 return ret;
1216}
1217
1218/*
1219 * Nuke all other threads in the group.
1220 */
1221int zap_other_threads(struct task_struct *p)
1222{
1223 struct task_struct *t = p;
1224 int count = 0;
1225
1226 p->signal->group_stop_count = 0;
1227
1228 while_each_thread(p, t) {
1229 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1230 count++;
1231
1232 /* Don't bother with already dead threads */
1233 if (t->exit_state)
1234 continue;
1235 sigaddset(&t->pending.signal, SIGKILL);
1236 signal_wake_up(t, 1);
1237 }
1238
1239 return count;
1240}
1241
1242struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1243 unsigned long *flags)
1244{
1245 struct sighand_struct *sighand;
1246
1247 for (;;) {
1248 /*
1249 * Disable interrupts early to avoid deadlocks.
1250 * See rcu_read_unlock() comment header for details.
1251 */
1252 local_irq_save(*flags);
1253 rcu_read_lock();
1254 sighand = rcu_dereference(tsk->sighand);
1255 if (unlikely(sighand == NULL)) {
1256 rcu_read_unlock();
1257 local_irq_restore(*flags);
1258 break;
1259 }
1260 /*
1261 * This sighand can be already freed and even reused, but
1262 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1263 * initializes ->siglock: this slab can't go away, it has
1264 * the same object type, ->siglock can't be reinitialized.
1265 *
1266 * We need to ensure that tsk->sighand is still the same
1267 * after we take the lock, we can race with de_thread() or
1268 * __exit_signal(). In the latter case the next iteration
1269 * must see ->sighand == NULL.
1270 */
1271 spin_lock(&sighand->siglock);
1272 if (likely(sighand == tsk->sighand)) {
1273 rcu_read_unlock();
1274 break;
1275 }
1276 spin_unlock(&sighand->siglock);
1277 rcu_read_unlock();
1278 local_irq_restore(*flags);
1279 }
1280
1281 return sighand;
1282}
1283
1284/*
1285 * send signal info to all the members of a group
1286 */
1287int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1288{
1289 int ret;
1290
1291 rcu_read_lock();
1292 ret = check_kill_permission(sig, info, p);
1293 rcu_read_unlock();
1294
1295 if (!ret && sig)
1296 ret = do_send_sig_info(sig, info, p, true);
1297
1298 return ret;
1299}
1300
1301/*
1302 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1303 * control characters do (^C, ^Z etc)
1304 * - the caller must hold at least a readlock on tasklist_lock
1305 */
1306int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1307{
1308 struct task_struct *p = NULL;
1309 int retval, success;
1310
1311 success = 0;
1312 retval = -ESRCH;
1313 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1314 int err = group_send_sig_info(sig, info, p);
1315 success |= !err;
1316 retval = err;
1317 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1318 return success ? 0 : retval;
1319}
1320
1321int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1322{
1323 int error = -ESRCH;
1324 struct task_struct *p;
1325
1326 for (;;) {
1327 rcu_read_lock();
1328 p = pid_task(pid, PIDTYPE_PID);
1329 if (p)
1330 error = group_send_sig_info(sig, info, p);
1331 rcu_read_unlock();
1332 if (likely(!p || error != -ESRCH))
1333 return error;
1334
1335 /*
1336 * The task was unhashed in between, try again. If it
1337 * is dead, pid_task() will return NULL, if we race with
1338 * de_thread() it will find the new leader.
1339 */
1340 }
1341}
1342
1343static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1344{
1345 int error;
1346 rcu_read_lock();
1347 error = kill_pid_info(sig, info, find_vpid(pid));
1348 rcu_read_unlock();
1349 return error;
1350}
1351
1352static int kill_as_cred_perm(const struct cred *cred,
1353 struct task_struct *target)
1354{
1355 const struct cred *pcred = __task_cred(target);
1356 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1357 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1358 return 0;
1359 return 1;
1360}
1361
1362/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1363int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1364 const struct cred *cred)
1365{
1366 int ret = -EINVAL;
1367 struct task_struct *p;
1368 unsigned long flags;
1369
1370 if (!valid_signal(sig))
1371 return ret;
1372
1373 rcu_read_lock();
1374 p = pid_task(pid, PIDTYPE_PID);
1375 if (!p) {
1376 ret = -ESRCH;
1377 goto out_unlock;
1378 }
1379 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1380 ret = -EPERM;
1381 goto out_unlock;
1382 }
1383 ret = security_task_kill(p, info, sig, cred);
1384 if (ret)
1385 goto out_unlock;
1386
1387 if (sig) {
1388 if (lock_task_sighand(p, &flags)) {
1389 ret = __send_signal(sig, info, p, 1, 0);
1390 unlock_task_sighand(p, &flags);
1391 } else
1392 ret = -ESRCH;
1393 }
1394out_unlock:
1395 rcu_read_unlock();
1396 return ret;
1397}
1398EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1399
1400/*
1401 * kill_something_info() interprets pid in interesting ways just like kill(2).
1402 *
1403 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1404 * is probably wrong. Should make it like BSD or SYSV.
1405 */
1406
1407static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1408{
1409 int ret;
1410
1411 if (pid > 0) {
1412 rcu_read_lock();
1413 ret = kill_pid_info(sig, info, find_vpid(pid));
1414 rcu_read_unlock();
1415 return ret;
1416 }
1417
1418 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1419 if (pid == INT_MIN)
1420 return -ESRCH;
1421
1422 read_lock(&tasklist_lock);
1423 if (pid != -1) {
1424 ret = __kill_pgrp_info(sig, info,
1425 pid ? find_vpid(-pid) : task_pgrp(current));
1426 } else {
1427 int retval = 0, count = 0;
1428 struct task_struct * p;
1429
1430 for_each_process(p) {
1431 if (task_pid_vnr(p) > 1 &&
1432 !same_thread_group(p, current)) {
1433 int err = group_send_sig_info(sig, info, p);
1434 ++count;
1435 if (err != -EPERM)
1436 retval = err;
1437 }
1438 }
1439 ret = count ? retval : -ESRCH;
1440 }
1441 read_unlock(&tasklist_lock);
1442
1443 return ret;
1444}
1445
1446/*
1447 * These are for backward compatibility with the rest of the kernel source.
1448 */
1449
1450int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1451{
1452 /*
1453 * Make sure legacy kernel users don't send in bad values
1454 * (normal paths check this in check_kill_permission).
1455 */
1456 if (!valid_signal(sig))
1457 return -EINVAL;
1458
1459 return do_send_sig_info(sig, info, p, false);
1460}
1461
1462#define __si_special(priv) \
1463 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1464
1465int
1466send_sig(int sig, struct task_struct *p, int priv)
1467{
1468 return send_sig_info(sig, __si_special(priv), p);
1469}
1470
1471void
1472force_sig(int sig, struct task_struct *p)
1473{
1474 force_sig_info(sig, SEND_SIG_PRIV, p);
1475}
1476
1477/*
1478 * When things go south during signal handling, we
1479 * will force a SIGSEGV. And if the signal that caused
1480 * the problem was already a SIGSEGV, we'll want to
1481 * make sure we don't even try to deliver the signal..
1482 */
1483int
1484force_sigsegv(int sig, struct task_struct *p)
1485{
1486 if (sig == SIGSEGV) {
1487 unsigned long flags;
1488 spin_lock_irqsave(&p->sighand->siglock, flags);
1489 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1490 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1491 }
1492 force_sig(SIGSEGV, p);
1493 return 0;
1494}
1495
1496int force_sig_fault(int sig, int code, void __user *addr
1497 ___ARCH_SI_TRAPNO(int trapno)
1498 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1499 , struct task_struct *t)
1500{
1501 struct siginfo info;
1502
1503 clear_siginfo(&info);
1504 info.si_signo = sig;
1505 info.si_errno = 0;
1506 info.si_code = code;
1507 info.si_addr = addr;
1508#ifdef __ARCH_SI_TRAPNO
1509 info.si_trapno = trapno;
1510#endif
1511#ifdef __ia64__
1512 info.si_imm = imm;
1513 info.si_flags = flags;
1514 info.si_isr = isr;
1515#endif
1516 return force_sig_info(info.si_signo, &info, t);
1517}
1518
1519int send_sig_fault(int sig, int code, void __user *addr
1520 ___ARCH_SI_TRAPNO(int trapno)
1521 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1522 , struct task_struct *t)
1523{
1524 struct siginfo info;
1525
1526 clear_siginfo(&info);
1527 info.si_signo = sig;
1528 info.si_errno = 0;
1529 info.si_code = code;
1530 info.si_addr = addr;
1531#ifdef __ARCH_SI_TRAPNO
1532 info.si_trapno = trapno;
1533#endif
1534#ifdef __ia64__
1535 info.si_imm = imm;
1536 info.si_flags = flags;
1537 info.si_isr = isr;
1538#endif
1539 return send_sig_info(info.si_signo, &info, t);
1540}
1541
1542#if defined(BUS_MCEERR_AO) && defined(BUS_MCEERR_AR)
1543int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1544{
1545 struct siginfo info;
1546
1547 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1548 clear_siginfo(&info);
1549 info.si_signo = SIGBUS;
1550 info.si_errno = 0;
1551 info.si_code = code;
1552 info.si_addr = addr;
1553 info.si_addr_lsb = lsb;
1554 return force_sig_info(info.si_signo, &info, t);
1555}
1556
1557int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1558{
1559 struct siginfo info;
1560
1561 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1562 clear_siginfo(&info);
1563 info.si_signo = SIGBUS;
1564 info.si_errno = 0;
1565 info.si_code = code;
1566 info.si_addr = addr;
1567 info.si_addr_lsb = lsb;
1568 return send_sig_info(info.si_signo, &info, t);
1569}
1570EXPORT_SYMBOL(send_sig_mceerr);
1571#endif
1572
1573#ifdef SEGV_BNDERR
1574int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1575{
1576 struct siginfo info;
1577
1578 clear_siginfo(&info);
1579 info.si_signo = SIGSEGV;
1580 info.si_errno = 0;
1581 info.si_code = SEGV_BNDERR;
1582 info.si_addr = addr;
1583 info.si_lower = lower;
1584 info.si_upper = upper;
1585 return force_sig_info(info.si_signo, &info, current);
1586}
1587#endif
1588
1589#ifdef SEGV_PKUERR
1590int force_sig_pkuerr(void __user *addr, u32 pkey)
1591{
1592 struct siginfo info;
1593
1594 clear_siginfo(&info);
1595 info.si_signo = SIGSEGV;
1596 info.si_errno = 0;
1597 info.si_code = SEGV_PKUERR;
1598 info.si_addr = addr;
1599 info.si_pkey = pkey;
1600 return force_sig_info(info.si_signo, &info, current);
1601}
1602#endif
1603
1604/* For the crazy architectures that include trap information in
1605 * the errno field, instead of an actual errno value.
1606 */
1607int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1608{
1609 struct siginfo info;
1610
1611 clear_siginfo(&info);
1612 info.si_signo = SIGTRAP;
1613 info.si_errno = errno;
1614 info.si_code = TRAP_HWBKPT;
1615 info.si_addr = addr;
1616 return force_sig_info(info.si_signo, &info, current);
1617}
1618
1619int kill_pgrp(struct pid *pid, int sig, int priv)
1620{
1621 int ret;
1622
1623 read_lock(&tasklist_lock);
1624 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1625 read_unlock(&tasklist_lock);
1626
1627 return ret;
1628}
1629EXPORT_SYMBOL(kill_pgrp);
1630
1631int kill_pid(struct pid *pid, int sig, int priv)
1632{
1633 return kill_pid_info(sig, __si_special(priv), pid);
1634}
1635EXPORT_SYMBOL(kill_pid);
1636
1637/*
1638 * These functions support sending signals using preallocated sigqueue
1639 * structures. This is needed "because realtime applications cannot
1640 * afford to lose notifications of asynchronous events, like timer
1641 * expirations or I/O completions". In the case of POSIX Timers
1642 * we allocate the sigqueue structure from the timer_create. If this
1643 * allocation fails we are able to report the failure to the application
1644 * with an EAGAIN error.
1645 */
1646struct sigqueue *sigqueue_alloc(void)
1647{
1648 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1649
1650 if (q)
1651 q->flags |= SIGQUEUE_PREALLOC;
1652
1653 return q;
1654}
1655
1656void sigqueue_free(struct sigqueue *q)
1657{
1658 unsigned long flags;
1659 spinlock_t *lock = ¤t->sighand->siglock;
1660
1661 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1662 /*
1663 * We must hold ->siglock while testing q->list
1664 * to serialize with collect_signal() or with
1665 * __exit_signal()->flush_sigqueue().
1666 */
1667 spin_lock_irqsave(lock, flags);
1668 q->flags &= ~SIGQUEUE_PREALLOC;
1669 /*
1670 * If it is queued it will be freed when dequeued,
1671 * like the "regular" sigqueue.
1672 */
1673 if (!list_empty(&q->list))
1674 q = NULL;
1675 spin_unlock_irqrestore(lock, flags);
1676
1677 if (q)
1678 __sigqueue_free(q);
1679}
1680
1681int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1682{
1683 int sig = q->info.si_signo;
1684 struct sigpending *pending;
1685 unsigned long flags;
1686 int ret, result;
1687
1688 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1689
1690 ret = -1;
1691 if (!likely(lock_task_sighand(t, &flags)))
1692 goto ret;
1693
1694 ret = 1; /* the signal is ignored */
1695 result = TRACE_SIGNAL_IGNORED;
1696 if (!prepare_signal(sig, t, false))
1697 goto out;
1698
1699 ret = 0;
1700 if (unlikely(!list_empty(&q->list))) {
1701 /*
1702 * If an SI_TIMER entry is already queue just increment
1703 * the overrun count.
1704 */
1705 BUG_ON(q->info.si_code != SI_TIMER);
1706 q->info.si_overrun++;
1707 result = TRACE_SIGNAL_ALREADY_PENDING;
1708 goto out;
1709 }
1710 q->info.si_overrun = 0;
1711
1712 signalfd_notify(t, sig);
1713 pending = group ? &t->signal->shared_pending : &t->pending;
1714 list_add_tail(&q->list, &pending->list);
1715 sigaddset(&pending->signal, sig);
1716 complete_signal(sig, t, group);
1717 result = TRACE_SIGNAL_DELIVERED;
1718out:
1719 trace_signal_generate(sig, &q->info, t, group, result);
1720 unlock_task_sighand(t, &flags);
1721ret:
1722 return ret;
1723}
1724
1725/*
1726 * Let a parent know about the death of a child.
1727 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1728 *
1729 * Returns true if our parent ignored us and so we've switched to
1730 * self-reaping.
1731 */
1732bool do_notify_parent(struct task_struct *tsk, int sig)
1733{
1734 struct siginfo info;
1735 unsigned long flags;
1736 struct sighand_struct *psig;
1737 bool autoreap = false;
1738 u64 utime, stime;
1739
1740 BUG_ON(sig == -1);
1741
1742 /* do_notify_parent_cldstop should have been called instead. */
1743 BUG_ON(task_is_stopped_or_traced(tsk));
1744
1745 BUG_ON(!tsk->ptrace &&
1746 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1747
1748 if (sig != SIGCHLD) {
1749 /*
1750 * This is only possible if parent == real_parent.
1751 * Check if it has changed security domain.
1752 */
1753 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1754 sig = SIGCHLD;
1755 }
1756
1757 clear_siginfo(&info);
1758 info.si_signo = sig;
1759 info.si_errno = 0;
1760 /*
1761 * We are under tasklist_lock here so our parent is tied to
1762 * us and cannot change.
1763 *
1764 * task_active_pid_ns will always return the same pid namespace
1765 * until a task passes through release_task.
1766 *
1767 * write_lock() currently calls preempt_disable() which is the
1768 * same as rcu_read_lock(), but according to Oleg, this is not
1769 * correct to rely on this
1770 */
1771 rcu_read_lock();
1772 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1773 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1774 task_uid(tsk));
1775 rcu_read_unlock();
1776
1777 task_cputime(tsk, &utime, &stime);
1778 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1779 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1780
1781 info.si_status = tsk->exit_code & 0x7f;
1782 if (tsk->exit_code & 0x80)
1783 info.si_code = CLD_DUMPED;
1784 else if (tsk->exit_code & 0x7f)
1785 info.si_code = CLD_KILLED;
1786 else {
1787 info.si_code = CLD_EXITED;
1788 info.si_status = tsk->exit_code >> 8;
1789 }
1790
1791 psig = tsk->parent->sighand;
1792 spin_lock_irqsave(&psig->siglock, flags);
1793 if (!tsk->ptrace && sig == SIGCHLD &&
1794 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1795 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1796 /*
1797 * We are exiting and our parent doesn't care. POSIX.1
1798 * defines special semantics for setting SIGCHLD to SIG_IGN
1799 * or setting the SA_NOCLDWAIT flag: we should be reaped
1800 * automatically and not left for our parent's wait4 call.
1801 * Rather than having the parent do it as a magic kind of
1802 * signal handler, we just set this to tell do_exit that we
1803 * can be cleaned up without becoming a zombie. Note that
1804 * we still call __wake_up_parent in this case, because a
1805 * blocked sys_wait4 might now return -ECHILD.
1806 *
1807 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1808 * is implementation-defined: we do (if you don't want
1809 * it, just use SIG_IGN instead).
1810 */
1811 autoreap = true;
1812 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1813 sig = 0;
1814 }
1815 if (valid_signal(sig) && sig)
1816 __group_send_sig_info(sig, &info, tsk->parent);
1817 __wake_up_parent(tsk, tsk->parent);
1818 spin_unlock_irqrestore(&psig->siglock, flags);
1819
1820 return autoreap;
1821}
1822
1823/**
1824 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1825 * @tsk: task reporting the state change
1826 * @for_ptracer: the notification is for ptracer
1827 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1828 *
1829 * Notify @tsk's parent that the stopped/continued state has changed. If
1830 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1831 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1832 *
1833 * CONTEXT:
1834 * Must be called with tasklist_lock at least read locked.
1835 */
1836static void do_notify_parent_cldstop(struct task_struct *tsk,
1837 bool for_ptracer, int why)
1838{
1839 struct siginfo info;
1840 unsigned long flags;
1841 struct task_struct *parent;
1842 struct sighand_struct *sighand;
1843 u64 utime, stime;
1844
1845 if (for_ptracer) {
1846 parent = tsk->parent;
1847 } else {
1848 tsk = tsk->group_leader;
1849 parent = tsk->real_parent;
1850 }
1851
1852 clear_siginfo(&info);
1853 info.si_signo = SIGCHLD;
1854 info.si_errno = 0;
1855 /*
1856 * see comment in do_notify_parent() about the following 4 lines
1857 */
1858 rcu_read_lock();
1859 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1860 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1861 rcu_read_unlock();
1862
1863 task_cputime(tsk, &utime, &stime);
1864 info.si_utime = nsec_to_clock_t(utime);
1865 info.si_stime = nsec_to_clock_t(stime);
1866
1867 info.si_code = why;
1868 switch (why) {
1869 case CLD_CONTINUED:
1870 info.si_status = SIGCONT;
1871 break;
1872 case CLD_STOPPED:
1873 info.si_status = tsk->signal->group_exit_code & 0x7f;
1874 break;
1875 case CLD_TRAPPED:
1876 info.si_status = tsk->exit_code & 0x7f;
1877 break;
1878 default:
1879 BUG();
1880 }
1881
1882 sighand = parent->sighand;
1883 spin_lock_irqsave(&sighand->siglock, flags);
1884 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1885 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1886 __group_send_sig_info(SIGCHLD, &info, parent);
1887 /*
1888 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1889 */
1890 __wake_up_parent(tsk, parent);
1891 spin_unlock_irqrestore(&sighand->siglock, flags);
1892}
1893
1894static inline int may_ptrace_stop(void)
1895{
1896 if (!likely(current->ptrace))
1897 return 0;
1898 /*
1899 * Are we in the middle of do_coredump?
1900 * If so and our tracer is also part of the coredump stopping
1901 * is a deadlock situation, and pointless because our tracer
1902 * is dead so don't allow us to stop.
1903 * If SIGKILL was already sent before the caller unlocked
1904 * ->siglock we must see ->core_state != NULL. Otherwise it
1905 * is safe to enter schedule().
1906 *
1907 * This is almost outdated, a task with the pending SIGKILL can't
1908 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1909 * after SIGKILL was already dequeued.
1910 */
1911 if (unlikely(current->mm->core_state) &&
1912 unlikely(current->mm == current->parent->mm))
1913 return 0;
1914
1915 return 1;
1916}
1917
1918/*
1919 * Return non-zero if there is a SIGKILL that should be waking us up.
1920 * Called with the siglock held.
1921 */
1922static int sigkill_pending(struct task_struct *tsk)
1923{
1924 return sigismember(&tsk->pending.signal, SIGKILL) ||
1925 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1926}
1927
1928/*
1929 * This must be called with current->sighand->siglock held.
1930 *
1931 * This should be the path for all ptrace stops.
1932 * We always set current->last_siginfo while stopped here.
1933 * That makes it a way to test a stopped process for
1934 * being ptrace-stopped vs being job-control-stopped.
1935 *
1936 * If we actually decide not to stop at all because the tracer
1937 * is gone, we keep current->exit_code unless clear_code.
1938 */
1939static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1940 __releases(¤t->sighand->siglock)
1941 __acquires(¤t->sighand->siglock)
1942{
1943 bool gstop_done = false;
1944
1945 if (arch_ptrace_stop_needed(exit_code, info)) {
1946 /*
1947 * The arch code has something special to do before a
1948 * ptrace stop. This is allowed to block, e.g. for faults
1949 * on user stack pages. We can't keep the siglock while
1950 * calling arch_ptrace_stop, so we must release it now.
1951 * To preserve proper semantics, we must do this before
1952 * any signal bookkeeping like checking group_stop_count.
1953 * Meanwhile, a SIGKILL could come in before we retake the
1954 * siglock. That must prevent us from sleeping in TASK_TRACED.
1955 * So after regaining the lock, we must check for SIGKILL.
1956 */
1957 spin_unlock_irq(¤t->sighand->siglock);
1958 arch_ptrace_stop(exit_code, info);
1959 spin_lock_irq(¤t->sighand->siglock);
1960 if (sigkill_pending(current))
1961 return;
1962 }
1963
1964 set_special_state(TASK_TRACED);
1965
1966 /*
1967 * We're committing to trapping. TRACED should be visible before
1968 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1969 * Also, transition to TRACED and updates to ->jobctl should be
1970 * atomic with respect to siglock and should be done after the arch
1971 * hook as siglock is released and regrabbed across it.
1972 *
1973 * TRACER TRACEE
1974 *
1975 * ptrace_attach()
1976 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
1977 * do_wait()
1978 * set_current_state() smp_wmb();
1979 * ptrace_do_wait()
1980 * wait_task_stopped()
1981 * task_stopped_code()
1982 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
1983 */
1984 smp_wmb();
1985
1986 current->last_siginfo = info;
1987 current->exit_code = exit_code;
1988
1989 /*
1990 * If @why is CLD_STOPPED, we're trapping to participate in a group
1991 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1992 * across siglock relocks since INTERRUPT was scheduled, PENDING
1993 * could be clear now. We act as if SIGCONT is received after
1994 * TASK_TRACED is entered - ignore it.
1995 */
1996 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1997 gstop_done = task_participate_group_stop(current);
1998
1999 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2000 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2001 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2002 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2003
2004 /* entering a trap, clear TRAPPING */
2005 task_clear_jobctl_trapping(current);
2006
2007 spin_unlock_irq(¤t->sighand->siglock);
2008 read_lock(&tasklist_lock);
2009 if (may_ptrace_stop()) {
2010 /*
2011 * Notify parents of the stop.
2012 *
2013 * While ptraced, there are two parents - the ptracer and
2014 * the real_parent of the group_leader. The ptracer should
2015 * know about every stop while the real parent is only
2016 * interested in the completion of group stop. The states
2017 * for the two don't interact with each other. Notify
2018 * separately unless they're gonna be duplicates.
2019 */
2020 do_notify_parent_cldstop(current, true, why);
2021 if (gstop_done && ptrace_reparented(current))
2022 do_notify_parent_cldstop(current, false, why);
2023
2024 /*
2025 * Don't want to allow preemption here, because
2026 * sys_ptrace() needs this task to be inactive.
2027 *
2028 * XXX: implement read_unlock_no_resched().
2029 */
2030 preempt_disable();
2031 read_unlock(&tasklist_lock);
2032 preempt_enable_no_resched();
2033 freezable_schedule();
2034 } else {
2035 /*
2036 * By the time we got the lock, our tracer went away.
2037 * Don't drop the lock yet, another tracer may come.
2038 *
2039 * If @gstop_done, the ptracer went away between group stop
2040 * completion and here. During detach, it would have set
2041 * JOBCTL_STOP_PENDING on us and we'll re-enter
2042 * TASK_STOPPED in do_signal_stop() on return, so notifying
2043 * the real parent of the group stop completion is enough.
2044 */
2045 if (gstop_done)
2046 do_notify_parent_cldstop(current, false, why);
2047
2048 /* tasklist protects us from ptrace_freeze_traced() */
2049 __set_current_state(TASK_RUNNING);
2050 if (clear_code)
2051 current->exit_code = 0;
2052 read_unlock(&tasklist_lock);
2053 }
2054
2055 /*
2056 * We are back. Now reacquire the siglock before touching
2057 * last_siginfo, so that we are sure to have synchronized with
2058 * any signal-sending on another CPU that wants to examine it.
2059 */
2060 spin_lock_irq(¤t->sighand->siglock);
2061 current->last_siginfo = NULL;
2062
2063 /* LISTENING can be set only during STOP traps, clear it */
2064 current->jobctl &= ~JOBCTL_LISTENING;
2065
2066 /*
2067 * Queued signals ignored us while we were stopped for tracing.
2068 * So check for any that we should take before resuming user mode.
2069 * This sets TIF_SIGPENDING, but never clears it.
2070 */
2071 recalc_sigpending_tsk(current);
2072}
2073
2074static void ptrace_do_notify(int signr, int exit_code, int why)
2075{
2076 siginfo_t info;
2077
2078 clear_siginfo(&info);
2079 info.si_signo = signr;
2080 info.si_code = exit_code;
2081 info.si_pid = task_pid_vnr(current);
2082 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2083
2084 /* Let the debugger run. */
2085 ptrace_stop(exit_code, why, 1, &info);
2086}
2087
2088void ptrace_notify(int exit_code)
2089{
2090 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2091 if (unlikely(current->task_works))
2092 task_work_run();
2093
2094 spin_lock_irq(¤t->sighand->siglock);
2095 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2096 spin_unlock_irq(¤t->sighand->siglock);
2097}
2098
2099/**
2100 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2101 * @signr: signr causing group stop if initiating
2102 *
2103 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2104 * and participate in it. If already set, participate in the existing
2105 * group stop. If participated in a group stop (and thus slept), %true is
2106 * returned with siglock released.
2107 *
2108 * If ptraced, this function doesn't handle stop itself. Instead,
2109 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2110 * untouched. The caller must ensure that INTERRUPT trap handling takes
2111 * places afterwards.
2112 *
2113 * CONTEXT:
2114 * Must be called with @current->sighand->siglock held, which is released
2115 * on %true return.
2116 *
2117 * RETURNS:
2118 * %false if group stop is already cancelled or ptrace trap is scheduled.
2119 * %true if participated in group stop.
2120 */
2121static bool do_signal_stop(int signr)
2122 __releases(¤t->sighand->siglock)
2123{
2124 struct signal_struct *sig = current->signal;
2125
2126 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2127 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2128 struct task_struct *t;
2129
2130 /* signr will be recorded in task->jobctl for retries */
2131 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2132
2133 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2134 unlikely(signal_group_exit(sig)))
2135 return false;
2136 /*
2137 * There is no group stop already in progress. We must
2138 * initiate one now.
2139 *
2140 * While ptraced, a task may be resumed while group stop is
2141 * still in effect and then receive a stop signal and
2142 * initiate another group stop. This deviates from the
2143 * usual behavior as two consecutive stop signals can't
2144 * cause two group stops when !ptraced. That is why we
2145 * also check !task_is_stopped(t) below.
2146 *
2147 * The condition can be distinguished by testing whether
2148 * SIGNAL_STOP_STOPPED is already set. Don't generate
2149 * group_exit_code in such case.
2150 *
2151 * This is not necessary for SIGNAL_STOP_CONTINUED because
2152 * an intervening stop signal is required to cause two
2153 * continued events regardless of ptrace.
2154 */
2155 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2156 sig->group_exit_code = signr;
2157
2158 sig->group_stop_count = 0;
2159
2160 if (task_set_jobctl_pending(current, signr | gstop))
2161 sig->group_stop_count++;
2162
2163 t = current;
2164 while_each_thread(current, t) {
2165 /*
2166 * Setting state to TASK_STOPPED for a group
2167 * stop is always done with the siglock held,
2168 * so this check has no races.
2169 */
2170 if (!task_is_stopped(t) &&
2171 task_set_jobctl_pending(t, signr | gstop)) {
2172 sig->group_stop_count++;
2173 if (likely(!(t->ptrace & PT_SEIZED)))
2174 signal_wake_up(t, 0);
2175 else
2176 ptrace_trap_notify(t);
2177 }
2178 }
2179 }
2180
2181 if (likely(!current->ptrace)) {
2182 int notify = 0;
2183
2184 /*
2185 * If there are no other threads in the group, or if there
2186 * is a group stop in progress and we are the last to stop,
2187 * report to the parent.
2188 */
2189 if (task_participate_group_stop(current))
2190 notify = CLD_STOPPED;
2191
2192 set_special_state(TASK_STOPPED);
2193 spin_unlock_irq(¤t->sighand->siglock);
2194
2195 /*
2196 * Notify the parent of the group stop completion. Because
2197 * we're not holding either the siglock or tasklist_lock
2198 * here, ptracer may attach inbetween; however, this is for
2199 * group stop and should always be delivered to the real
2200 * parent of the group leader. The new ptracer will get
2201 * its notification when this task transitions into
2202 * TASK_TRACED.
2203 */
2204 if (notify) {
2205 read_lock(&tasklist_lock);
2206 do_notify_parent_cldstop(current, false, notify);
2207 read_unlock(&tasklist_lock);
2208 }
2209
2210 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2211 freezable_schedule();
2212 return true;
2213 } else {
2214 /*
2215 * While ptraced, group stop is handled by STOP trap.
2216 * Schedule it and let the caller deal with it.
2217 */
2218 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2219 return false;
2220 }
2221}
2222
2223/**
2224 * do_jobctl_trap - take care of ptrace jobctl traps
2225 *
2226 * When PT_SEIZED, it's used for both group stop and explicit
2227 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2228 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2229 * the stop signal; otherwise, %SIGTRAP.
2230 *
2231 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2232 * number as exit_code and no siginfo.
2233 *
2234 * CONTEXT:
2235 * Must be called with @current->sighand->siglock held, which may be
2236 * released and re-acquired before returning with intervening sleep.
2237 */
2238static void do_jobctl_trap(void)
2239{
2240 struct signal_struct *signal = current->signal;
2241 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2242
2243 if (current->ptrace & PT_SEIZED) {
2244 if (!signal->group_stop_count &&
2245 !(signal->flags & SIGNAL_STOP_STOPPED))
2246 signr = SIGTRAP;
2247 WARN_ON_ONCE(!signr);
2248 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2249 CLD_STOPPED);
2250 } else {
2251 WARN_ON_ONCE(!signr);
2252 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2253 current->exit_code = 0;
2254 }
2255}
2256
2257static int ptrace_signal(int signr, siginfo_t *info)
2258{
2259 /*
2260 * We do not check sig_kernel_stop(signr) but set this marker
2261 * unconditionally because we do not know whether debugger will
2262 * change signr. This flag has no meaning unless we are going
2263 * to stop after return from ptrace_stop(). In this case it will
2264 * be checked in do_signal_stop(), we should only stop if it was
2265 * not cleared by SIGCONT while we were sleeping. See also the
2266 * comment in dequeue_signal().
2267 */
2268 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2269 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2270
2271 /* We're back. Did the debugger cancel the sig? */
2272 signr = current->exit_code;
2273 if (signr == 0)
2274 return signr;
2275
2276 current->exit_code = 0;
2277
2278 /*
2279 * Update the siginfo structure if the signal has
2280 * changed. If the debugger wanted something
2281 * specific in the siginfo structure then it should
2282 * have updated *info via PTRACE_SETSIGINFO.
2283 */
2284 if (signr != info->si_signo) {
2285 clear_siginfo(info);
2286 info->si_signo = signr;
2287 info->si_errno = 0;
2288 info->si_code = SI_USER;
2289 rcu_read_lock();
2290 info->si_pid = task_pid_vnr(current->parent);
2291 info->si_uid = from_kuid_munged(current_user_ns(),
2292 task_uid(current->parent));
2293 rcu_read_unlock();
2294 }
2295
2296 /* If the (new) signal is now blocked, requeue it. */
2297 if (sigismember(¤t->blocked, signr)) {
2298 specific_send_sig_info(signr, info, current);
2299 signr = 0;
2300 }
2301
2302 return signr;
2303}
2304
2305int get_signal(struct ksignal *ksig)
2306{
2307 struct sighand_struct *sighand = current->sighand;
2308 struct signal_struct *signal = current->signal;
2309 int signr;
2310
2311 if (unlikely(current->task_works))
2312 task_work_run();
2313
2314 if (unlikely(uprobe_deny_signal()))
2315 return 0;
2316
2317 /*
2318 * Do this once, we can't return to user-mode if freezing() == T.
2319 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2320 * thus do not need another check after return.
2321 */
2322 try_to_freeze();
2323
2324relock:
2325 spin_lock_irq(&sighand->siglock);
2326 /*
2327 * Every stopped thread goes here after wakeup. Check to see if
2328 * we should notify the parent, prepare_signal(SIGCONT) encodes
2329 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2330 */
2331 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2332 int why;
2333
2334 if (signal->flags & SIGNAL_CLD_CONTINUED)
2335 why = CLD_CONTINUED;
2336 else
2337 why = CLD_STOPPED;
2338
2339 signal->flags &= ~SIGNAL_CLD_MASK;
2340
2341 spin_unlock_irq(&sighand->siglock);
2342
2343 /*
2344 * Notify the parent that we're continuing. This event is
2345 * always per-process and doesn't make whole lot of sense
2346 * for ptracers, who shouldn't consume the state via
2347 * wait(2) either, but, for backward compatibility, notify
2348 * the ptracer of the group leader too unless it's gonna be
2349 * a duplicate.
2350 */
2351 read_lock(&tasklist_lock);
2352 do_notify_parent_cldstop(current, false, why);
2353
2354 if (ptrace_reparented(current->group_leader))
2355 do_notify_parent_cldstop(current->group_leader,
2356 true, why);
2357 read_unlock(&tasklist_lock);
2358
2359 goto relock;
2360 }
2361
2362 for (;;) {
2363 struct k_sigaction *ka;
2364
2365 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2366 do_signal_stop(0))
2367 goto relock;
2368
2369 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2370 do_jobctl_trap();
2371 spin_unlock_irq(&sighand->siglock);
2372 goto relock;
2373 }
2374
2375 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2376
2377 if (!signr)
2378 break; /* will return 0 */
2379
2380 if (unlikely(current->ptrace) && signr != SIGKILL) {
2381 signr = ptrace_signal(signr, &ksig->info);
2382 if (!signr)
2383 continue;
2384 }
2385
2386 ka = &sighand->action[signr-1];
2387
2388 /* Trace actually delivered signals. */
2389 trace_signal_deliver(signr, &ksig->info, ka);
2390
2391 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2392 continue;
2393 if (ka->sa.sa_handler != SIG_DFL) {
2394 /* Run the handler. */
2395 ksig->ka = *ka;
2396
2397 if (ka->sa.sa_flags & SA_ONESHOT)
2398 ka->sa.sa_handler = SIG_DFL;
2399
2400 break; /* will return non-zero "signr" value */
2401 }
2402
2403 /*
2404 * Now we are doing the default action for this signal.
2405 */
2406 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2407 continue;
2408
2409 /*
2410 * Global init gets no signals it doesn't want.
2411 * Container-init gets no signals it doesn't want from same
2412 * container.
2413 *
2414 * Note that if global/container-init sees a sig_kernel_only()
2415 * signal here, the signal must have been generated internally
2416 * or must have come from an ancestor namespace. In either
2417 * case, the signal cannot be dropped.
2418 */
2419 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2420 !sig_kernel_only(signr))
2421 continue;
2422
2423 if (sig_kernel_stop(signr)) {
2424 /*
2425 * The default action is to stop all threads in
2426 * the thread group. The job control signals
2427 * do nothing in an orphaned pgrp, but SIGSTOP
2428 * always works. Note that siglock needs to be
2429 * dropped during the call to is_orphaned_pgrp()
2430 * because of lock ordering with tasklist_lock.
2431 * This allows an intervening SIGCONT to be posted.
2432 * We need to check for that and bail out if necessary.
2433 */
2434 if (signr != SIGSTOP) {
2435 spin_unlock_irq(&sighand->siglock);
2436
2437 /* signals can be posted during this window */
2438
2439 if (is_current_pgrp_orphaned())
2440 goto relock;
2441
2442 spin_lock_irq(&sighand->siglock);
2443 }
2444
2445 if (likely(do_signal_stop(ksig->info.si_signo))) {
2446 /* It released the siglock. */
2447 goto relock;
2448 }
2449
2450 /*
2451 * We didn't actually stop, due to a race
2452 * with SIGCONT or something like that.
2453 */
2454 continue;
2455 }
2456
2457 spin_unlock_irq(&sighand->siglock);
2458
2459 /*
2460 * Anything else is fatal, maybe with a core dump.
2461 */
2462 current->flags |= PF_SIGNALED;
2463
2464 if (sig_kernel_coredump(signr)) {
2465 if (print_fatal_signals)
2466 print_fatal_signal(ksig->info.si_signo);
2467 proc_coredump_connector(current);
2468 /*
2469 * If it was able to dump core, this kills all
2470 * other threads in the group and synchronizes with
2471 * their demise. If we lost the race with another
2472 * thread getting here, it set group_exit_code
2473 * first and our do_group_exit call below will use
2474 * that value and ignore the one we pass it.
2475 */
2476 do_coredump(&ksig->info);
2477 }
2478
2479 /*
2480 * Death signals, no core dump.
2481 */
2482 do_group_exit(ksig->info.si_signo);
2483 /* NOTREACHED */
2484 }
2485 spin_unlock_irq(&sighand->siglock);
2486
2487 ksig->sig = signr;
2488 return ksig->sig > 0;
2489}
2490
2491/**
2492 * signal_delivered -
2493 * @ksig: kernel signal struct
2494 * @stepping: nonzero if debugger single-step or block-step in use
2495 *
2496 * This function should be called when a signal has successfully been
2497 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2498 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2499 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2500 */
2501static void signal_delivered(struct ksignal *ksig, int stepping)
2502{
2503 sigset_t blocked;
2504
2505 /* A signal was successfully delivered, and the
2506 saved sigmask was stored on the signal frame,
2507 and will be restored by sigreturn. So we can
2508 simply clear the restore sigmask flag. */
2509 clear_restore_sigmask();
2510
2511 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2512 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2513 sigaddset(&blocked, ksig->sig);
2514 set_current_blocked(&blocked);
2515 tracehook_signal_handler(stepping);
2516}
2517
2518void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2519{
2520 if (failed)
2521 force_sigsegv(ksig->sig, current);
2522 else
2523 signal_delivered(ksig, stepping);
2524}
2525
2526/*
2527 * It could be that complete_signal() picked us to notify about the
2528 * group-wide signal. Other threads should be notified now to take
2529 * the shared signals in @which since we will not.
2530 */
2531static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2532{
2533 sigset_t retarget;
2534 struct task_struct *t;
2535
2536 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2537 if (sigisemptyset(&retarget))
2538 return;
2539
2540 t = tsk;
2541 while_each_thread(tsk, t) {
2542 if (t->flags & PF_EXITING)
2543 continue;
2544
2545 if (!has_pending_signals(&retarget, &t->blocked))
2546 continue;
2547 /* Remove the signals this thread can handle. */
2548 sigandsets(&retarget, &retarget, &t->blocked);
2549
2550 if (!signal_pending(t))
2551 signal_wake_up(t, 0);
2552
2553 if (sigisemptyset(&retarget))
2554 break;
2555 }
2556}
2557
2558void exit_signals(struct task_struct *tsk)
2559{
2560 int group_stop = 0;
2561 sigset_t unblocked;
2562
2563 /*
2564 * @tsk is about to have PF_EXITING set - lock out users which
2565 * expect stable threadgroup.
2566 */
2567 cgroup_threadgroup_change_begin(tsk);
2568
2569 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2570 tsk->flags |= PF_EXITING;
2571 cgroup_threadgroup_change_end(tsk);
2572 return;
2573 }
2574
2575 spin_lock_irq(&tsk->sighand->siglock);
2576 /*
2577 * From now this task is not visible for group-wide signals,
2578 * see wants_signal(), do_signal_stop().
2579 */
2580 tsk->flags |= PF_EXITING;
2581
2582 cgroup_threadgroup_change_end(tsk);
2583
2584 if (!signal_pending(tsk))
2585 goto out;
2586
2587 unblocked = tsk->blocked;
2588 signotset(&unblocked);
2589 retarget_shared_pending(tsk, &unblocked);
2590
2591 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2592 task_participate_group_stop(tsk))
2593 group_stop = CLD_STOPPED;
2594out:
2595 spin_unlock_irq(&tsk->sighand->siglock);
2596
2597 /*
2598 * If group stop has completed, deliver the notification. This
2599 * should always go to the real parent of the group leader.
2600 */
2601 if (unlikely(group_stop)) {
2602 read_lock(&tasklist_lock);
2603 do_notify_parent_cldstop(tsk, false, group_stop);
2604 read_unlock(&tasklist_lock);
2605 }
2606}
2607
2608EXPORT_SYMBOL(recalc_sigpending);
2609EXPORT_SYMBOL_GPL(dequeue_signal);
2610EXPORT_SYMBOL(flush_signals);
2611EXPORT_SYMBOL(force_sig);
2612EXPORT_SYMBOL(send_sig);
2613EXPORT_SYMBOL(send_sig_info);
2614EXPORT_SYMBOL(sigprocmask);
2615
2616/*
2617 * System call entry points.
2618 */
2619
2620/**
2621 * sys_restart_syscall - restart a system call
2622 */
2623SYSCALL_DEFINE0(restart_syscall)
2624{
2625 struct restart_block *restart = ¤t->restart_block;
2626 return restart->fn(restart);
2627}
2628
2629long do_no_restart_syscall(struct restart_block *param)
2630{
2631 return -EINTR;
2632}
2633
2634static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2635{
2636 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2637 sigset_t newblocked;
2638 /* A set of now blocked but previously unblocked signals. */
2639 sigandnsets(&newblocked, newset, ¤t->blocked);
2640 retarget_shared_pending(tsk, &newblocked);
2641 }
2642 tsk->blocked = *newset;
2643 recalc_sigpending();
2644}
2645
2646/**
2647 * set_current_blocked - change current->blocked mask
2648 * @newset: new mask
2649 *
2650 * It is wrong to change ->blocked directly, this helper should be used
2651 * to ensure the process can't miss a shared signal we are going to block.
2652 */
2653void set_current_blocked(sigset_t *newset)
2654{
2655 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2656 __set_current_blocked(newset);
2657}
2658
2659void __set_current_blocked(const sigset_t *newset)
2660{
2661 struct task_struct *tsk = current;
2662
2663 /*
2664 * In case the signal mask hasn't changed, there is nothing we need
2665 * to do. The current->blocked shouldn't be modified by other task.
2666 */
2667 if (sigequalsets(&tsk->blocked, newset))
2668 return;
2669
2670 spin_lock_irq(&tsk->sighand->siglock);
2671 __set_task_blocked(tsk, newset);
2672 spin_unlock_irq(&tsk->sighand->siglock);
2673}
2674
2675/*
2676 * This is also useful for kernel threads that want to temporarily
2677 * (or permanently) block certain signals.
2678 *
2679 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2680 * interface happily blocks "unblockable" signals like SIGKILL
2681 * and friends.
2682 */
2683int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2684{
2685 struct task_struct *tsk = current;
2686 sigset_t newset;
2687
2688 /* Lockless, only current can change ->blocked, never from irq */
2689 if (oldset)
2690 *oldset = tsk->blocked;
2691
2692 switch (how) {
2693 case SIG_BLOCK:
2694 sigorsets(&newset, &tsk->blocked, set);
2695 break;
2696 case SIG_UNBLOCK:
2697 sigandnsets(&newset, &tsk->blocked, set);
2698 break;
2699 case SIG_SETMASK:
2700 newset = *set;
2701 break;
2702 default:
2703 return -EINVAL;
2704 }
2705
2706 __set_current_blocked(&newset);
2707 return 0;
2708}
2709
2710/**
2711 * sys_rt_sigprocmask - change the list of currently blocked signals
2712 * @how: whether to add, remove, or set signals
2713 * @nset: stores pending signals
2714 * @oset: previous value of signal mask if non-null
2715 * @sigsetsize: size of sigset_t type
2716 */
2717SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2718 sigset_t __user *, oset, size_t, sigsetsize)
2719{
2720 sigset_t old_set, new_set;
2721 int error;
2722
2723 /* XXX: Don't preclude handling different sized sigset_t's. */
2724 if (sigsetsize != sizeof(sigset_t))
2725 return -EINVAL;
2726
2727 old_set = current->blocked;
2728
2729 if (nset) {
2730 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2731 return -EFAULT;
2732 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2733
2734 error = sigprocmask(how, &new_set, NULL);
2735 if (error)
2736 return error;
2737 }
2738
2739 if (oset) {
2740 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2741 return -EFAULT;
2742 }
2743
2744 return 0;
2745}
2746
2747#ifdef CONFIG_COMPAT
2748COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2749 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2750{
2751 sigset_t old_set = current->blocked;
2752
2753 /* XXX: Don't preclude handling different sized sigset_t's. */
2754 if (sigsetsize != sizeof(sigset_t))
2755 return -EINVAL;
2756
2757 if (nset) {
2758 sigset_t new_set;
2759 int error;
2760 if (get_compat_sigset(&new_set, nset))
2761 return -EFAULT;
2762 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2763
2764 error = sigprocmask(how, &new_set, NULL);
2765 if (error)
2766 return error;
2767 }
2768 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
2769}
2770#endif
2771
2772static int do_sigpending(sigset_t *set)
2773{
2774 spin_lock_irq(¤t->sighand->siglock);
2775 sigorsets(set, ¤t->pending.signal,
2776 ¤t->signal->shared_pending.signal);
2777 spin_unlock_irq(¤t->sighand->siglock);
2778
2779 /* Outside the lock because only this thread touches it. */
2780 sigandsets(set, ¤t->blocked, set);
2781 return 0;
2782}
2783
2784/**
2785 * sys_rt_sigpending - examine a pending signal that has been raised
2786 * while blocked
2787 * @uset: stores pending signals
2788 * @sigsetsize: size of sigset_t type or larger
2789 */
2790SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2791{
2792 sigset_t set;
2793 int err;
2794
2795 if (sigsetsize > sizeof(*uset))
2796 return -EINVAL;
2797
2798 err = do_sigpending(&set);
2799 if (!err && copy_to_user(uset, &set, sigsetsize))
2800 err = -EFAULT;
2801 return err;
2802}
2803
2804#ifdef CONFIG_COMPAT
2805COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2806 compat_size_t, sigsetsize)
2807{
2808 sigset_t set;
2809 int err;
2810
2811 if (sigsetsize > sizeof(*uset))
2812 return -EINVAL;
2813
2814 err = do_sigpending(&set);
2815 if (!err)
2816 err = put_compat_sigset(uset, &set, sigsetsize);
2817 return err;
2818}
2819#endif
2820
2821enum siginfo_layout siginfo_layout(int sig, int si_code)
2822{
2823 enum siginfo_layout layout = SIL_KILL;
2824 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
2825 static const struct {
2826 unsigned char limit, layout;
2827 } filter[] = {
2828 [SIGILL] = { NSIGILL, SIL_FAULT },
2829 [SIGFPE] = { NSIGFPE, SIL_FAULT },
2830 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
2831 [SIGBUS] = { NSIGBUS, SIL_FAULT },
2832 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
2833#if defined(SIGEMT) && defined(NSIGEMT)
2834 [SIGEMT] = { NSIGEMT, SIL_FAULT },
2835#endif
2836 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
2837 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
2838 [SIGSYS] = { NSIGSYS, SIL_SYS },
2839 };
2840 if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit))
2841 layout = filter[sig].layout;
2842 else if (si_code <= NSIGPOLL)
2843 layout = SIL_POLL;
2844 } else {
2845 if (si_code == SI_TIMER)
2846 layout = SIL_TIMER;
2847 else if (si_code == SI_SIGIO)
2848 layout = SIL_POLL;
2849 else if (si_code < 0)
2850 layout = SIL_RT;
2851 /* Tests to support buggy kernel ABIs */
2852#ifdef TRAP_FIXME
2853 if ((sig == SIGTRAP) && (si_code == TRAP_FIXME))
2854 layout = SIL_FAULT;
2855#endif
2856#ifdef FPE_FIXME
2857 if ((sig == SIGFPE) && (si_code == FPE_FIXME))
2858 layout = SIL_FAULT;
2859#endif
2860 }
2861 return layout;
2862}
2863
2864int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2865{
2866 int err;
2867
2868 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2869 return -EFAULT;
2870 if (from->si_code < 0)
2871 return __copy_to_user(to, from, sizeof(siginfo_t))
2872 ? -EFAULT : 0;
2873 /*
2874 * If you change siginfo_t structure, please be sure
2875 * this code is fixed accordingly.
2876 * Please remember to update the signalfd_copyinfo() function
2877 * inside fs/signalfd.c too, in case siginfo_t changes.
2878 * It should never copy any pad contained in the structure
2879 * to avoid security leaks, but must copy the generic
2880 * 3 ints plus the relevant union member.
2881 */
2882 err = __put_user(from->si_signo, &to->si_signo);
2883 err |= __put_user(from->si_errno, &to->si_errno);
2884 err |= __put_user(from->si_code, &to->si_code);
2885 switch (siginfo_layout(from->si_signo, from->si_code)) {
2886 case SIL_KILL:
2887 err |= __put_user(from->si_pid, &to->si_pid);
2888 err |= __put_user(from->si_uid, &to->si_uid);
2889 break;
2890 case SIL_TIMER:
2891 /* Unreached SI_TIMER is negative */
2892 break;
2893 case SIL_POLL:
2894 err |= __put_user(from->si_band, &to->si_band);
2895 err |= __put_user(from->si_fd, &to->si_fd);
2896 break;
2897 case SIL_FAULT:
2898 err |= __put_user(from->si_addr, &to->si_addr);
2899#ifdef __ARCH_SI_TRAPNO
2900 err |= __put_user(from->si_trapno, &to->si_trapno);
2901#endif
2902#ifdef __ia64__
2903 err |= __put_user(from->si_imm, &to->si_imm);
2904 err |= __put_user(from->si_flags, &to->si_flags);
2905 err |= __put_user(from->si_isr, &to->si_isr);
2906#endif
2907 /*
2908 * Other callers might not initialize the si_lsb field,
2909 * so check explicitly for the right codes here.
2910 */
2911#ifdef BUS_MCEERR_AR
2912 if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AR)
2913 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2914#endif
2915#ifdef BUS_MCEERR_AO
2916 if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AO)
2917 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2918#endif
2919#ifdef SEGV_BNDERR
2920 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2921 err |= __put_user(from->si_lower, &to->si_lower);
2922 err |= __put_user(from->si_upper, &to->si_upper);
2923 }
2924#endif
2925#ifdef SEGV_PKUERR
2926 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2927 err |= __put_user(from->si_pkey, &to->si_pkey);
2928#endif
2929 break;
2930 case SIL_CHLD:
2931 err |= __put_user(from->si_pid, &to->si_pid);
2932 err |= __put_user(from->si_uid, &to->si_uid);
2933 err |= __put_user(from->si_status, &to->si_status);
2934 err |= __put_user(from->si_utime, &to->si_utime);
2935 err |= __put_user(from->si_stime, &to->si_stime);
2936 break;
2937 case SIL_RT:
2938 err |= __put_user(from->si_pid, &to->si_pid);
2939 err |= __put_user(from->si_uid, &to->si_uid);
2940 err |= __put_user(from->si_ptr, &to->si_ptr);
2941 break;
2942 case SIL_SYS:
2943 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2944 err |= __put_user(from->si_syscall, &to->si_syscall);
2945 err |= __put_user(from->si_arch, &to->si_arch);
2946 break;
2947 }
2948 return err;
2949}
2950
2951#ifdef CONFIG_COMPAT
2952int copy_siginfo_to_user32(struct compat_siginfo __user *to,
2953 const struct siginfo *from)
2954#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
2955{
2956 return __copy_siginfo_to_user32(to, from, in_x32_syscall());
2957}
2958int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
2959 const struct siginfo *from, bool x32_ABI)
2960#endif
2961{
2962 struct compat_siginfo new;
2963 memset(&new, 0, sizeof(new));
2964
2965 new.si_signo = from->si_signo;
2966 new.si_errno = from->si_errno;
2967 new.si_code = from->si_code;
2968 switch(siginfo_layout(from->si_signo, from->si_code)) {
2969 case SIL_KILL:
2970 new.si_pid = from->si_pid;
2971 new.si_uid = from->si_uid;
2972 break;
2973 case SIL_TIMER:
2974 new.si_tid = from->si_tid;
2975 new.si_overrun = from->si_overrun;
2976 new.si_int = from->si_int;
2977 break;
2978 case SIL_POLL:
2979 new.si_band = from->si_band;
2980 new.si_fd = from->si_fd;
2981 break;
2982 case SIL_FAULT:
2983 new.si_addr = ptr_to_compat(from->si_addr);
2984#ifdef __ARCH_SI_TRAPNO
2985 new.si_trapno = from->si_trapno;
2986#endif
2987#ifdef BUS_MCEERR_AR
2988 if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AR))
2989 new.si_addr_lsb = from->si_addr_lsb;
2990#endif
2991#ifdef BUS_MCEERR_AO
2992 if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AO))
2993 new.si_addr_lsb = from->si_addr_lsb;
2994#endif
2995#ifdef SEGV_BNDERR
2996 if ((from->si_signo == SIGSEGV) &&
2997 (from->si_code == SEGV_BNDERR)) {
2998 new.si_lower = ptr_to_compat(from->si_lower);
2999 new.si_upper = ptr_to_compat(from->si_upper);
3000 }
3001#endif
3002#ifdef SEGV_PKUERR
3003 if ((from->si_signo == SIGSEGV) &&
3004 (from->si_code == SEGV_PKUERR))
3005 new.si_pkey = from->si_pkey;
3006#endif
3007
3008 break;
3009 case SIL_CHLD:
3010 new.si_pid = from->si_pid;
3011 new.si_uid = from->si_uid;
3012 new.si_status = from->si_status;
3013#ifdef CONFIG_X86_X32_ABI
3014 if (x32_ABI) {
3015 new._sifields._sigchld_x32._utime = from->si_utime;
3016 new._sifields._sigchld_x32._stime = from->si_stime;
3017 } else
3018#endif
3019 {
3020 new.si_utime = from->si_utime;
3021 new.si_stime = from->si_stime;
3022 }
3023 break;
3024 case SIL_RT:
3025 new.si_pid = from->si_pid;
3026 new.si_uid = from->si_uid;
3027 new.si_int = from->si_int;
3028 break;
3029 case SIL_SYS:
3030 new.si_call_addr = ptr_to_compat(from->si_call_addr);
3031 new.si_syscall = from->si_syscall;
3032 new.si_arch = from->si_arch;
3033 break;
3034 }
3035
3036 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3037 return -EFAULT;
3038
3039 return 0;
3040}
3041
3042int copy_siginfo_from_user32(struct siginfo *to,
3043 const struct compat_siginfo __user *ufrom)
3044{
3045 struct compat_siginfo from;
3046
3047 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3048 return -EFAULT;
3049
3050 clear_siginfo(to);
3051 to->si_signo = from.si_signo;
3052 to->si_errno = from.si_errno;
3053 to->si_code = from.si_code;
3054 switch(siginfo_layout(from.si_signo, from.si_code)) {
3055 case SIL_KILL:
3056 to->si_pid = from.si_pid;
3057 to->si_uid = from.si_uid;
3058 break;
3059 case SIL_TIMER:
3060 to->si_tid = from.si_tid;
3061 to->si_overrun = from.si_overrun;
3062 to->si_int = from.si_int;
3063 break;
3064 case SIL_POLL:
3065 to->si_band = from.si_band;
3066 to->si_fd = from.si_fd;
3067 break;
3068 case SIL_FAULT:
3069 to->si_addr = compat_ptr(from.si_addr);
3070#ifdef __ARCH_SI_TRAPNO
3071 to->si_trapno = from.si_trapno;
3072#endif
3073#ifdef BUS_MCEERR_AR
3074 if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AR))
3075 to->si_addr_lsb = from.si_addr_lsb;
3076#endif
3077#ifdef BUS_MCEER_AO
3078 if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AO))
3079 to->si_addr_lsb = from.si_addr_lsb;
3080#endif
3081#ifdef SEGV_BNDERR
3082 if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) {
3083 to->si_lower = compat_ptr(from.si_lower);
3084 to->si_upper = compat_ptr(from.si_upper);
3085 }
3086#endif
3087#ifdef SEGV_PKUERR
3088 if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR))
3089 to->si_pkey = from.si_pkey;
3090#endif
3091 break;
3092 case SIL_CHLD:
3093 to->si_pid = from.si_pid;
3094 to->si_uid = from.si_uid;
3095 to->si_status = from.si_status;
3096#ifdef CONFIG_X86_X32_ABI
3097 if (in_x32_syscall()) {
3098 to->si_utime = from._sifields._sigchld_x32._utime;
3099 to->si_stime = from._sifields._sigchld_x32._stime;
3100 } else
3101#endif
3102 {
3103 to->si_utime = from.si_utime;
3104 to->si_stime = from.si_stime;
3105 }
3106 break;
3107 case SIL_RT:
3108 to->si_pid = from.si_pid;
3109 to->si_uid = from.si_uid;
3110 to->si_int = from.si_int;
3111 break;
3112 case SIL_SYS:
3113 to->si_call_addr = compat_ptr(from.si_call_addr);
3114 to->si_syscall = from.si_syscall;
3115 to->si_arch = from.si_arch;
3116 break;
3117 }
3118 return 0;
3119}
3120#endif /* CONFIG_COMPAT */
3121
3122/**
3123 * do_sigtimedwait - wait for queued signals specified in @which
3124 * @which: queued signals to wait for
3125 * @info: if non-null, the signal's siginfo is returned here
3126 * @ts: upper bound on process time suspension
3127 */
3128static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
3129 const struct timespec *ts)
3130{
3131 ktime_t *to = NULL, timeout = KTIME_MAX;
3132 struct task_struct *tsk = current;
3133 sigset_t mask = *which;
3134 int sig, ret = 0;
3135
3136 if (ts) {
3137 if (!timespec_valid(ts))
3138 return -EINVAL;
3139 timeout = timespec_to_ktime(*ts);
3140 to = &timeout;
3141 }
3142
3143 /*
3144 * Invert the set of allowed signals to get those we want to block.
3145 */
3146 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3147 signotset(&mask);
3148
3149 spin_lock_irq(&tsk->sighand->siglock);
3150 sig = dequeue_signal(tsk, &mask, info);
3151 if (!sig && timeout) {
3152 /*
3153 * None ready, temporarily unblock those we're interested
3154 * while we are sleeping in so that we'll be awakened when
3155 * they arrive. Unblocking is always fine, we can avoid
3156 * set_current_blocked().
3157 */
3158 tsk->real_blocked = tsk->blocked;
3159 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3160 recalc_sigpending();
3161 spin_unlock_irq(&tsk->sighand->siglock);
3162
3163 __set_current_state(TASK_INTERRUPTIBLE);
3164 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3165 HRTIMER_MODE_REL);
3166 spin_lock_irq(&tsk->sighand->siglock);
3167 __set_task_blocked(tsk, &tsk->real_blocked);
3168 sigemptyset(&tsk->real_blocked);
3169 sig = dequeue_signal(tsk, &mask, info);
3170 }
3171 spin_unlock_irq(&tsk->sighand->siglock);
3172
3173 if (sig)
3174 return sig;
3175 return ret ? -EINTR : -EAGAIN;
3176}
3177
3178/**
3179 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3180 * in @uthese
3181 * @uthese: queued signals to wait for
3182 * @uinfo: if non-null, the signal's siginfo is returned here
3183 * @uts: upper bound on process time suspension
3184 * @sigsetsize: size of sigset_t type
3185 */
3186SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3187 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
3188 size_t, sigsetsize)
3189{
3190 sigset_t these;
3191 struct timespec ts;
3192 siginfo_t info;
3193 int ret;
3194
3195 /* XXX: Don't preclude handling different sized sigset_t's. */
3196 if (sigsetsize != sizeof(sigset_t))
3197 return -EINVAL;
3198
3199 if (copy_from_user(&these, uthese, sizeof(these)))
3200 return -EFAULT;
3201
3202 if (uts) {
3203 if (copy_from_user(&ts, uts, sizeof(ts)))
3204 return -EFAULT;
3205 }
3206
3207 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3208
3209 if (ret > 0 && uinfo) {
3210 if (copy_siginfo_to_user(uinfo, &info))
3211 ret = -EFAULT;
3212 }
3213
3214 return ret;
3215}
3216
3217#ifdef CONFIG_COMPAT
3218COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
3219 struct compat_siginfo __user *, uinfo,
3220 struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
3221{
3222 sigset_t s;
3223 struct timespec t;
3224 siginfo_t info;
3225 long ret;
3226
3227 if (sigsetsize != sizeof(sigset_t))
3228 return -EINVAL;
3229
3230 if (get_compat_sigset(&s, uthese))
3231 return -EFAULT;
3232
3233 if (uts) {
3234 if (compat_get_timespec(&t, uts))
3235 return -EFAULT;
3236 }
3237
3238 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3239
3240 if (ret > 0 && uinfo) {
3241 if (copy_siginfo_to_user32(uinfo, &info))
3242 ret = -EFAULT;
3243 }
3244
3245 return ret;
3246}
3247#endif
3248
3249/**
3250 * sys_kill - send a signal to a process
3251 * @pid: the PID of the process
3252 * @sig: signal to be sent
3253 */
3254SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3255{
3256 struct siginfo info;
3257
3258 clear_siginfo(&info);
3259 info.si_signo = sig;
3260 info.si_errno = 0;
3261 info.si_code = SI_USER;
3262 info.si_pid = task_tgid_vnr(current);
3263 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3264
3265 return kill_something_info(sig, &info, pid);
3266}
3267
3268static int
3269do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
3270{
3271 struct task_struct *p;
3272 int error = -ESRCH;
3273
3274 rcu_read_lock();
3275 p = find_task_by_vpid(pid);
3276 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3277 error = check_kill_permission(sig, info, p);
3278 /*
3279 * The null signal is a permissions and process existence
3280 * probe. No signal is actually delivered.
3281 */
3282 if (!error && sig) {
3283 error = do_send_sig_info(sig, info, p, false);
3284 /*
3285 * If lock_task_sighand() failed we pretend the task
3286 * dies after receiving the signal. The window is tiny,
3287 * and the signal is private anyway.
3288 */
3289 if (unlikely(error == -ESRCH))
3290 error = 0;
3291 }
3292 }
3293 rcu_read_unlock();
3294
3295 return error;
3296}
3297
3298static int do_tkill(pid_t tgid, pid_t pid, int sig)
3299{
3300 struct siginfo info;
3301
3302 clear_siginfo(&info);
3303 info.si_signo = sig;
3304 info.si_errno = 0;
3305 info.si_code = SI_TKILL;
3306 info.si_pid = task_tgid_vnr(current);
3307 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3308
3309 return do_send_specific(tgid, pid, sig, &info);
3310}
3311
3312/**
3313 * sys_tgkill - send signal to one specific thread
3314 * @tgid: the thread group ID of the thread
3315 * @pid: the PID of the thread
3316 * @sig: signal to be sent
3317 *
3318 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3319 * exists but it's not belonging to the target process anymore. This
3320 * method solves the problem of threads exiting and PIDs getting reused.
3321 */
3322SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3323{
3324 /* This is only valid for single tasks */
3325 if (pid <= 0 || tgid <= 0)
3326 return -EINVAL;
3327
3328 return do_tkill(tgid, pid, sig);
3329}
3330
3331/**
3332 * sys_tkill - send signal to one specific task
3333 * @pid: the PID of the task
3334 * @sig: signal to be sent
3335 *
3336 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3337 */
3338SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3339{
3340 /* This is only valid for single tasks */
3341 if (pid <= 0)
3342 return -EINVAL;
3343
3344 return do_tkill(0, pid, sig);
3345}
3346
3347static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3348{
3349 /* Not even root can pretend to send signals from the kernel.
3350 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3351 */
3352 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3353 (task_pid_vnr(current) != pid))
3354 return -EPERM;
3355
3356 info->si_signo = sig;
3357
3358 /* POSIX.1b doesn't mention process groups. */
3359 return kill_proc_info(sig, info, pid);
3360}
3361
3362/**
3363 * sys_rt_sigqueueinfo - send signal information to a signal
3364 * @pid: the PID of the thread
3365 * @sig: signal to be sent
3366 * @uinfo: signal info to be sent
3367 */
3368SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3369 siginfo_t __user *, uinfo)
3370{
3371 siginfo_t info;
3372 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3373 return -EFAULT;
3374 return do_rt_sigqueueinfo(pid, sig, &info);
3375}
3376
3377#ifdef CONFIG_COMPAT
3378COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3379 compat_pid_t, pid,
3380 int, sig,
3381 struct compat_siginfo __user *, uinfo)
3382{
3383 siginfo_t info;
3384 int ret = copy_siginfo_from_user32(&info, uinfo);
3385 if (unlikely(ret))
3386 return ret;
3387 return do_rt_sigqueueinfo(pid, sig, &info);
3388}
3389#endif
3390
3391static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3392{
3393 /* This is only valid for single tasks */
3394 if (pid <= 0 || tgid <= 0)
3395 return -EINVAL;
3396
3397 /* Not even root can pretend to send signals from the kernel.
3398 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3399 */
3400 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3401 (task_pid_vnr(current) != pid))
3402 return -EPERM;
3403
3404 info->si_signo = sig;
3405
3406 return do_send_specific(tgid, pid, sig, info);
3407}
3408
3409SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3410 siginfo_t __user *, uinfo)
3411{
3412 siginfo_t info;
3413
3414 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3415 return -EFAULT;
3416
3417 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3418}
3419
3420#ifdef CONFIG_COMPAT
3421COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3422 compat_pid_t, tgid,
3423 compat_pid_t, pid,
3424 int, sig,
3425 struct compat_siginfo __user *, uinfo)
3426{
3427 siginfo_t info;
3428
3429 if (copy_siginfo_from_user32(&info, uinfo))
3430 return -EFAULT;
3431 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3432}
3433#endif
3434
3435/*
3436 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3437 */
3438void kernel_sigaction(int sig, __sighandler_t action)
3439{
3440 spin_lock_irq(¤t->sighand->siglock);
3441 current->sighand->action[sig - 1].sa.sa_handler = action;
3442 if (action == SIG_IGN) {
3443 sigset_t mask;
3444
3445 sigemptyset(&mask);
3446 sigaddset(&mask, sig);
3447
3448 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3449 flush_sigqueue_mask(&mask, ¤t->pending);
3450 recalc_sigpending();
3451 }
3452 spin_unlock_irq(¤t->sighand->siglock);
3453}
3454EXPORT_SYMBOL(kernel_sigaction);
3455
3456void __weak sigaction_compat_abi(struct k_sigaction *act,
3457 struct k_sigaction *oact)
3458{
3459}
3460
3461int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3462{
3463 struct task_struct *p = current, *t;
3464 struct k_sigaction *k;
3465 sigset_t mask;
3466
3467 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3468 return -EINVAL;
3469
3470 k = &p->sighand->action[sig-1];
3471
3472 spin_lock_irq(&p->sighand->siglock);
3473 if (oact)
3474 *oact = *k;
3475
3476 sigaction_compat_abi(act, oact);
3477
3478 if (act) {
3479 sigdelsetmask(&act->sa.sa_mask,
3480 sigmask(SIGKILL) | sigmask(SIGSTOP));
3481 *k = *act;
3482 /*
3483 * POSIX 3.3.1.3:
3484 * "Setting a signal action to SIG_IGN for a signal that is
3485 * pending shall cause the pending signal to be discarded,
3486 * whether or not it is blocked."
3487 *
3488 * "Setting a signal action to SIG_DFL for a signal that is
3489 * pending and whose default action is to ignore the signal
3490 * (for example, SIGCHLD), shall cause the pending signal to
3491 * be discarded, whether or not it is blocked"
3492 */
3493 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3494 sigemptyset(&mask);
3495 sigaddset(&mask, sig);
3496 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3497 for_each_thread(p, t)
3498 flush_sigqueue_mask(&mask, &t->pending);
3499 }
3500 }
3501
3502 spin_unlock_irq(&p->sighand->siglock);
3503 return 0;
3504}
3505
3506static int
3507do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
3508{
3509 struct task_struct *t = current;
3510
3511 if (oss) {
3512 memset(oss, 0, sizeof(stack_t));
3513 oss->ss_sp = (void __user *) t->sas_ss_sp;
3514 oss->ss_size = t->sas_ss_size;
3515 oss->ss_flags = sas_ss_flags(sp) |
3516 (current->sas_ss_flags & SS_FLAG_BITS);
3517 }
3518
3519 if (ss) {
3520 void __user *ss_sp = ss->ss_sp;
3521 size_t ss_size = ss->ss_size;
3522 unsigned ss_flags = ss->ss_flags;
3523 int ss_mode;
3524
3525 if (unlikely(on_sig_stack(sp)))
3526 return -EPERM;
3527
3528 ss_mode = ss_flags & ~SS_FLAG_BITS;
3529 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3530 ss_mode != 0))
3531 return -EINVAL;
3532
3533 if (ss_mode == SS_DISABLE) {
3534 ss_size = 0;
3535 ss_sp = NULL;
3536 } else {
3537 if (unlikely(ss_size < MINSIGSTKSZ))
3538 return -ENOMEM;
3539 }
3540
3541 t->sas_ss_sp = (unsigned long) ss_sp;
3542 t->sas_ss_size = ss_size;
3543 t->sas_ss_flags = ss_flags;
3544 }
3545 return 0;
3546}
3547
3548SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3549{
3550 stack_t new, old;
3551 int err;
3552 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
3553 return -EFAULT;
3554 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
3555 current_user_stack_pointer());
3556 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
3557 err = -EFAULT;
3558 return err;
3559}
3560
3561int restore_altstack(const stack_t __user *uss)
3562{
3563 stack_t new;
3564 if (copy_from_user(&new, uss, sizeof(stack_t)))
3565 return -EFAULT;
3566 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
3567 /* squash all but EFAULT for now */
3568 return 0;
3569}
3570
3571int __save_altstack(stack_t __user *uss, unsigned long sp)
3572{
3573 struct task_struct *t = current;
3574 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3575 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3576 __put_user(t->sas_ss_size, &uss->ss_size);
3577 if (err)
3578 return err;
3579 if (t->sas_ss_flags & SS_AUTODISARM)
3580 sas_ss_reset(t);
3581 return 0;
3582}
3583
3584#ifdef CONFIG_COMPAT
3585static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
3586 compat_stack_t __user *uoss_ptr)
3587{
3588 stack_t uss, uoss;
3589 int ret;
3590
3591 if (uss_ptr) {
3592 compat_stack_t uss32;
3593 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3594 return -EFAULT;
3595 uss.ss_sp = compat_ptr(uss32.ss_sp);
3596 uss.ss_flags = uss32.ss_flags;
3597 uss.ss_size = uss32.ss_size;
3598 }
3599 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
3600 compat_user_stack_pointer());
3601 if (ret >= 0 && uoss_ptr) {
3602 compat_stack_t old;
3603 memset(&old, 0, sizeof(old));
3604 old.ss_sp = ptr_to_compat(uoss.ss_sp);
3605 old.ss_flags = uoss.ss_flags;
3606 old.ss_size = uoss.ss_size;
3607 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
3608 ret = -EFAULT;
3609 }
3610 return ret;
3611}
3612
3613COMPAT_SYSCALL_DEFINE2(sigaltstack,
3614 const compat_stack_t __user *, uss_ptr,
3615 compat_stack_t __user *, uoss_ptr)
3616{
3617 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
3618}
3619
3620int compat_restore_altstack(const compat_stack_t __user *uss)
3621{
3622 int err = do_compat_sigaltstack(uss, NULL);
3623 /* squash all but -EFAULT for now */
3624 return err == -EFAULT ? err : 0;
3625}
3626
3627int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3628{
3629 int err;
3630 struct task_struct *t = current;
3631 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3632 &uss->ss_sp) |
3633 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3634 __put_user(t->sas_ss_size, &uss->ss_size);
3635 if (err)
3636 return err;
3637 if (t->sas_ss_flags & SS_AUTODISARM)
3638 sas_ss_reset(t);
3639 return 0;
3640}
3641#endif
3642
3643#ifdef __ARCH_WANT_SYS_SIGPENDING
3644
3645/**
3646 * sys_sigpending - examine pending signals
3647 * @uset: where mask of pending signal is returned
3648 */
3649SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
3650{
3651 sigset_t set;
3652 int err;
3653
3654 if (sizeof(old_sigset_t) > sizeof(*uset))
3655 return -EINVAL;
3656
3657 err = do_sigpending(&set);
3658 if (!err && copy_to_user(uset, &set, sizeof(old_sigset_t)))
3659 err = -EFAULT;
3660 return err;
3661}
3662
3663#ifdef CONFIG_COMPAT
3664COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
3665{
3666 sigset_t set;
3667 int err = do_sigpending(&set);
3668 if (!err)
3669 err = put_user(set.sig[0], set32);
3670 return err;
3671}
3672#endif
3673
3674#endif
3675
3676#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3677/**
3678 * sys_sigprocmask - examine and change blocked signals
3679 * @how: whether to add, remove, or set signals
3680 * @nset: signals to add or remove (if non-null)
3681 * @oset: previous value of signal mask if non-null
3682 *
3683 * Some platforms have their own version with special arguments;
3684 * others support only sys_rt_sigprocmask.
3685 */
3686
3687SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3688 old_sigset_t __user *, oset)
3689{
3690 old_sigset_t old_set, new_set;
3691 sigset_t new_blocked;
3692
3693 old_set = current->blocked.sig[0];
3694
3695 if (nset) {
3696 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3697 return -EFAULT;
3698
3699 new_blocked = current->blocked;
3700
3701 switch (how) {
3702 case SIG_BLOCK:
3703 sigaddsetmask(&new_blocked, new_set);
3704 break;
3705 case SIG_UNBLOCK:
3706 sigdelsetmask(&new_blocked, new_set);
3707 break;
3708 case SIG_SETMASK:
3709 new_blocked.sig[0] = new_set;
3710 break;
3711 default:
3712 return -EINVAL;
3713 }
3714
3715 set_current_blocked(&new_blocked);
3716 }
3717
3718 if (oset) {
3719 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3720 return -EFAULT;
3721 }
3722
3723 return 0;
3724}
3725#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3726
3727#ifndef CONFIG_ODD_RT_SIGACTION
3728/**
3729 * sys_rt_sigaction - alter an action taken by a process
3730 * @sig: signal to be sent
3731 * @act: new sigaction
3732 * @oact: used to save the previous sigaction
3733 * @sigsetsize: size of sigset_t type
3734 */
3735SYSCALL_DEFINE4(rt_sigaction, int, sig,
3736 const struct sigaction __user *, act,
3737 struct sigaction __user *, oact,
3738 size_t, sigsetsize)
3739{
3740 struct k_sigaction new_sa, old_sa;
3741 int ret = -EINVAL;
3742
3743 /* XXX: Don't preclude handling different sized sigset_t's. */
3744 if (sigsetsize != sizeof(sigset_t))
3745 goto out;
3746
3747 if (act) {
3748 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3749 return -EFAULT;
3750 }
3751
3752 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3753
3754 if (!ret && oact) {
3755 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3756 return -EFAULT;
3757 }
3758out:
3759 return ret;
3760}
3761#ifdef CONFIG_COMPAT
3762COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3763 const struct compat_sigaction __user *, act,
3764 struct compat_sigaction __user *, oact,
3765 compat_size_t, sigsetsize)
3766{
3767 struct k_sigaction new_ka, old_ka;
3768#ifdef __ARCH_HAS_SA_RESTORER
3769 compat_uptr_t restorer;
3770#endif
3771 int ret;
3772
3773 /* XXX: Don't preclude handling different sized sigset_t's. */
3774 if (sigsetsize != sizeof(compat_sigset_t))
3775 return -EINVAL;
3776
3777 if (act) {
3778 compat_uptr_t handler;
3779 ret = get_user(handler, &act->sa_handler);
3780 new_ka.sa.sa_handler = compat_ptr(handler);
3781#ifdef __ARCH_HAS_SA_RESTORER
3782 ret |= get_user(restorer, &act->sa_restorer);
3783 new_ka.sa.sa_restorer = compat_ptr(restorer);
3784#endif
3785 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
3786 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3787 if (ret)
3788 return -EFAULT;
3789 }
3790
3791 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3792 if (!ret && oact) {
3793 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3794 &oact->sa_handler);
3795 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
3796 sizeof(oact->sa_mask));
3797 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3798#ifdef __ARCH_HAS_SA_RESTORER
3799 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3800 &oact->sa_restorer);
3801#endif
3802 }
3803 return ret;
3804}
3805#endif
3806#endif /* !CONFIG_ODD_RT_SIGACTION */
3807
3808#ifdef CONFIG_OLD_SIGACTION
3809SYSCALL_DEFINE3(sigaction, int, sig,
3810 const struct old_sigaction __user *, act,
3811 struct old_sigaction __user *, oact)
3812{
3813 struct k_sigaction new_ka, old_ka;
3814 int ret;
3815
3816 if (act) {
3817 old_sigset_t mask;
3818 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3819 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3820 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3821 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3822 __get_user(mask, &act->sa_mask))
3823 return -EFAULT;
3824#ifdef __ARCH_HAS_KA_RESTORER
3825 new_ka.ka_restorer = NULL;
3826#endif
3827 siginitset(&new_ka.sa.sa_mask, mask);
3828 }
3829
3830 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3831
3832 if (!ret && oact) {
3833 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3834 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3835 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3836 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3837 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3838 return -EFAULT;
3839 }
3840
3841 return ret;
3842}
3843#endif
3844#ifdef CONFIG_COMPAT_OLD_SIGACTION
3845COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3846 const struct compat_old_sigaction __user *, act,
3847 struct compat_old_sigaction __user *, oact)
3848{
3849 struct k_sigaction new_ka, old_ka;
3850 int ret;
3851 compat_old_sigset_t mask;
3852 compat_uptr_t handler, restorer;
3853
3854 if (act) {
3855 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3856 __get_user(handler, &act->sa_handler) ||
3857 __get_user(restorer, &act->sa_restorer) ||
3858 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3859 __get_user(mask, &act->sa_mask))
3860 return -EFAULT;
3861
3862#ifdef __ARCH_HAS_KA_RESTORER
3863 new_ka.ka_restorer = NULL;
3864#endif
3865 new_ka.sa.sa_handler = compat_ptr(handler);
3866 new_ka.sa.sa_restorer = compat_ptr(restorer);
3867 siginitset(&new_ka.sa.sa_mask, mask);
3868 }
3869
3870 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3871
3872 if (!ret && oact) {
3873 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3874 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3875 &oact->sa_handler) ||
3876 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3877 &oact->sa_restorer) ||
3878 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3879 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3880 return -EFAULT;
3881 }
3882 return ret;
3883}
3884#endif
3885
3886#ifdef CONFIG_SGETMASK_SYSCALL
3887
3888/*
3889 * For backwards compatibility. Functionality superseded by sigprocmask.
3890 */
3891SYSCALL_DEFINE0(sgetmask)
3892{
3893 /* SMP safe */
3894 return current->blocked.sig[0];
3895}
3896
3897SYSCALL_DEFINE1(ssetmask, int, newmask)
3898{
3899 int old = current->blocked.sig[0];
3900 sigset_t newset;
3901
3902 siginitset(&newset, newmask);
3903 set_current_blocked(&newset);
3904
3905 return old;
3906}
3907#endif /* CONFIG_SGETMASK_SYSCALL */
3908
3909#ifdef __ARCH_WANT_SYS_SIGNAL
3910/*
3911 * For backwards compatibility. Functionality superseded by sigaction.
3912 */
3913SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3914{
3915 struct k_sigaction new_sa, old_sa;
3916 int ret;
3917
3918 new_sa.sa.sa_handler = handler;
3919 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3920 sigemptyset(&new_sa.sa.sa_mask);
3921
3922 ret = do_sigaction(sig, &new_sa, &old_sa);
3923
3924 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3925}
3926#endif /* __ARCH_WANT_SYS_SIGNAL */
3927
3928#ifdef __ARCH_WANT_SYS_PAUSE
3929
3930SYSCALL_DEFINE0(pause)
3931{
3932 while (!signal_pending(current)) {
3933 __set_current_state(TASK_INTERRUPTIBLE);
3934 schedule();
3935 }
3936 return -ERESTARTNOHAND;
3937}
3938
3939#endif
3940
3941static int sigsuspend(sigset_t *set)
3942{
3943 current->saved_sigmask = current->blocked;
3944 set_current_blocked(set);
3945
3946 while (!signal_pending(current)) {
3947 __set_current_state(TASK_INTERRUPTIBLE);
3948 schedule();
3949 }
3950 set_restore_sigmask();
3951 return -ERESTARTNOHAND;
3952}
3953
3954/**
3955 * sys_rt_sigsuspend - replace the signal mask for a value with the
3956 * @unewset value until a signal is received
3957 * @unewset: new signal mask value
3958 * @sigsetsize: size of sigset_t type
3959 */
3960SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3961{
3962 sigset_t newset;
3963
3964 /* XXX: Don't preclude handling different sized sigset_t's. */
3965 if (sigsetsize != sizeof(sigset_t))
3966 return -EINVAL;
3967
3968 if (copy_from_user(&newset, unewset, sizeof(newset)))
3969 return -EFAULT;
3970 return sigsuspend(&newset);
3971}
3972
3973#ifdef CONFIG_COMPAT
3974COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3975{
3976 sigset_t newset;
3977
3978 /* XXX: Don't preclude handling different sized sigset_t's. */
3979 if (sigsetsize != sizeof(sigset_t))
3980 return -EINVAL;
3981
3982 if (get_compat_sigset(&newset, unewset))
3983 return -EFAULT;
3984 return sigsuspend(&newset);
3985}
3986#endif
3987
3988#ifdef CONFIG_OLD_SIGSUSPEND
3989SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3990{
3991 sigset_t blocked;
3992 siginitset(&blocked, mask);
3993 return sigsuspend(&blocked);
3994}
3995#endif
3996#ifdef CONFIG_OLD_SIGSUSPEND3
3997SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3998{
3999 sigset_t blocked;
4000 siginitset(&blocked, mask);
4001 return sigsuspend(&blocked);
4002}
4003#endif
4004
4005__weak const char *arch_vma_name(struct vm_area_struct *vma)
4006{
4007 return NULL;
4008}
4009
4010void __init signals_init(void)
4011{
4012 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
4013 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
4014 != offsetof(struct siginfo, _sifields._pad));
4015 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4016
4017 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4018}
4019
4020#ifdef CONFIG_KGDB_KDB
4021#include <linux/kdb.h>
4022/*
4023 * kdb_send_sig - Allows kdb to send signals without exposing
4024 * signal internals. This function checks if the required locks are
4025 * available before calling the main signal code, to avoid kdb
4026 * deadlocks.
4027 */
4028void kdb_send_sig(struct task_struct *t, int sig)
4029{
4030 static struct task_struct *kdb_prev_t;
4031 int new_t, ret;
4032 if (!spin_trylock(&t->sighand->siglock)) {
4033 kdb_printf("Can't do kill command now.\n"
4034 "The sigmask lock is held somewhere else in "
4035 "kernel, try again later\n");
4036 return;
4037 }
4038 new_t = kdb_prev_t != t;
4039 kdb_prev_t = t;
4040 if (t->state != TASK_RUNNING && new_t) {
4041 spin_unlock(&t->sighand->siglock);
4042 kdb_printf("Process is not RUNNING, sending a signal from "
4043 "kdb risks deadlock\n"
4044 "on the run queue locks. "
4045 "The signal has _not_ been sent.\n"
4046 "Reissue the kill command if you want to risk "
4047 "the deadlock.\n");
4048 return;
4049 }
4050 ret = send_signal(sig, SEND_SIG_PRIV, t, false);
4051 spin_unlock(&t->sighand->siglock);
4052 if (ret)
4053 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4054 sig, t->pid);
4055 else
4056 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4057}
4058#endif /* CONFIG_KGDB_KDB */