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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#include <uapi/linux/pidfd.h>
51
52#define CREATE_TRACE_POINTS
53#include <trace/events/signal.h>
54
55#include <asm/param.h>
56#include <linux/uaccess.h>
57#include <asm/unistd.h>
58#include <asm/siginfo.h>
59#include <asm/cacheflush.h>
60#include <asm/syscall.h> /* for syscall_get_* */
61
62#include "time/posix-timers.h"
63
64/*
65 * SLAB caches for signal bits.
66 */
67
68static struct kmem_cache *sigqueue_cachep;
69
70int print_fatal_signals __read_mostly;
71
72static void __user *sig_handler(struct task_struct *t, int sig)
73{
74 return t->sighand->action[sig - 1].sa.sa_handler;
75}
76
77static inline bool sig_handler_ignored(void __user *handler, int sig)
78{
79 /* Is it explicitly or implicitly ignored? */
80 return handler == SIG_IGN ||
81 (handler == SIG_DFL && sig_kernel_ignore(sig));
82}
83
84static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
85{
86 void __user *handler;
87
88 handler = sig_handler(t, sig);
89
90 /* SIGKILL and SIGSTOP may not be sent to the global init */
91 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
92 return true;
93
94 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
95 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
96 return true;
97
98 /* Only allow kernel generated signals to this kthread */
99 if (unlikely((t->flags & PF_KTHREAD) &&
100 (handler == SIG_KTHREAD_KERNEL) && !force))
101 return true;
102
103 return sig_handler_ignored(handler, sig);
104}
105
106static bool sig_ignored(struct task_struct *t, int sig, bool force)
107{
108 /*
109 * Blocked signals are never ignored, since the
110 * signal handler may change by the time it is
111 * unblocked.
112 */
113 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
114 return false;
115
116 /*
117 * Tracers may want to know about even ignored signal unless it
118 * is SIGKILL which can't be reported anyway but can be ignored
119 * by SIGNAL_UNKILLABLE task.
120 */
121 if (t->ptrace && sig != SIGKILL)
122 return false;
123
124 return sig_task_ignored(t, sig, force);
125}
126
127/*
128 * Re-calculate pending state from the set of locally pending
129 * signals, globally pending signals, and blocked signals.
130 */
131static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
132{
133 unsigned long ready;
134 long i;
135
136 switch (_NSIG_WORDS) {
137 default:
138 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
139 ready |= signal->sig[i] &~ blocked->sig[i];
140 break;
141
142 case 4: ready = signal->sig[3] &~ blocked->sig[3];
143 ready |= signal->sig[2] &~ blocked->sig[2];
144 ready |= signal->sig[1] &~ blocked->sig[1];
145 ready |= signal->sig[0] &~ blocked->sig[0];
146 break;
147
148 case 2: ready = signal->sig[1] &~ blocked->sig[1];
149 ready |= signal->sig[0] &~ blocked->sig[0];
150 break;
151
152 case 1: ready = signal->sig[0] &~ blocked->sig[0];
153 }
154 return ready != 0;
155}
156
157#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
158
159static bool recalc_sigpending_tsk(struct task_struct *t)
160{
161 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
162 PENDING(&t->pending, &t->blocked) ||
163 PENDING(&t->signal->shared_pending, &t->blocked) ||
164 cgroup_task_frozen(t)) {
165 set_tsk_thread_flag(t, TIF_SIGPENDING);
166 return true;
167 }
168
169 /*
170 * We must never clear the flag in another thread, or in current
171 * when it's possible the current syscall is returning -ERESTART*.
172 * So we don't clear it here, and only callers who know they should do.
173 */
174 return false;
175}
176
177void recalc_sigpending(void)
178{
179 if (!recalc_sigpending_tsk(current) && !freezing(current))
180 clear_thread_flag(TIF_SIGPENDING);
181
182}
183EXPORT_SYMBOL(recalc_sigpending);
184
185void calculate_sigpending(void)
186{
187 /* Have any signals or users of TIF_SIGPENDING been delayed
188 * until after fork?
189 */
190 spin_lock_irq(¤t->sighand->siglock);
191 set_tsk_thread_flag(current, TIF_SIGPENDING);
192 recalc_sigpending();
193 spin_unlock_irq(¤t->sighand->siglock);
194}
195
196/* Given the mask, find the first available signal that should be serviced. */
197
198#define SYNCHRONOUS_MASK \
199 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
200 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
201
202int next_signal(struct sigpending *pending, sigset_t *mask)
203{
204 unsigned long i, *s, *m, x;
205 int sig = 0;
206
207 s = pending->signal.sig;
208 m = mask->sig;
209
210 /*
211 * Handle the first word specially: it contains the
212 * synchronous signals that need to be dequeued first.
213 */
214 x = *s &~ *m;
215 if (x) {
216 if (x & SYNCHRONOUS_MASK)
217 x &= SYNCHRONOUS_MASK;
218 sig = ffz(~x) + 1;
219 return sig;
220 }
221
222 switch (_NSIG_WORDS) {
223 default:
224 for (i = 1; i < _NSIG_WORDS; ++i) {
225 x = *++s &~ *++m;
226 if (!x)
227 continue;
228 sig = ffz(~x) + i*_NSIG_BPW + 1;
229 break;
230 }
231 break;
232
233 case 2:
234 x = s[1] &~ m[1];
235 if (!x)
236 break;
237 sig = ffz(~x) + _NSIG_BPW + 1;
238 break;
239
240 case 1:
241 /* Nothing to do */
242 break;
243 }
244
245 return sig;
246}
247
248static inline void print_dropped_signal(int sig)
249{
250 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
251
252 if (!print_fatal_signals)
253 return;
254
255 if (!__ratelimit(&ratelimit_state))
256 return;
257
258 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
259 current->comm, current->pid, sig);
260}
261
262/**
263 * task_set_jobctl_pending - set jobctl pending bits
264 * @task: target task
265 * @mask: pending bits to set
266 *
267 * Clear @mask from @task->jobctl. @mask must be subset of
268 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
269 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
270 * cleared. If @task is already being killed or exiting, this function
271 * becomes noop.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 *
276 * RETURNS:
277 * %true if @mask is set, %false if made noop because @task was dying.
278 */
279bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
280{
281 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
282 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
283 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
284
285 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
286 return false;
287
288 if (mask & JOBCTL_STOP_SIGMASK)
289 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
290
291 task->jobctl |= mask;
292 return true;
293}
294
295/**
296 * task_clear_jobctl_trapping - clear jobctl trapping bit
297 * @task: target task
298 *
299 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
300 * Clear it and wake up the ptracer. Note that we don't need any further
301 * locking. @task->siglock guarantees that @task->parent points to the
302 * ptracer.
303 *
304 * CONTEXT:
305 * Must be called with @task->sighand->siglock held.
306 */
307void task_clear_jobctl_trapping(struct task_struct *task)
308{
309 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
310 task->jobctl &= ~JOBCTL_TRAPPING;
311 smp_mb(); /* advised by wake_up_bit() */
312 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
313 }
314}
315
316/**
317 * task_clear_jobctl_pending - clear jobctl pending bits
318 * @task: target task
319 * @mask: pending bits to clear
320 *
321 * Clear @mask from @task->jobctl. @mask must be subset of
322 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
323 * STOP bits are cleared together.
324 *
325 * If clearing of @mask leaves no stop or trap pending, this function calls
326 * task_clear_jobctl_trapping().
327 *
328 * CONTEXT:
329 * Must be called with @task->sighand->siglock held.
330 */
331void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
332{
333 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
334
335 if (mask & JOBCTL_STOP_PENDING)
336 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
337
338 task->jobctl &= ~mask;
339
340 if (!(task->jobctl & JOBCTL_PENDING_MASK))
341 task_clear_jobctl_trapping(task);
342}
343
344/**
345 * task_participate_group_stop - participate in a group stop
346 * @task: task participating in a group stop
347 *
348 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
349 * Group stop states are cleared and the group stop count is consumed if
350 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
351 * stop, the appropriate `SIGNAL_*` flags are set.
352 *
353 * CONTEXT:
354 * Must be called with @task->sighand->siglock held.
355 *
356 * RETURNS:
357 * %true if group stop completion should be notified to the parent, %false
358 * otherwise.
359 */
360static bool task_participate_group_stop(struct task_struct *task)
361{
362 struct signal_struct *sig = task->signal;
363 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
364
365 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
366
367 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
368
369 if (!consume)
370 return false;
371
372 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
373 sig->group_stop_count--;
374
375 /*
376 * Tell the caller to notify completion iff we are entering into a
377 * fresh group stop. Read comment in do_signal_stop() for details.
378 */
379 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
380 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
381 return true;
382 }
383 return false;
384}
385
386void task_join_group_stop(struct task_struct *task)
387{
388 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
389 struct signal_struct *sig = current->signal;
390
391 if (sig->group_stop_count) {
392 sig->group_stop_count++;
393 mask |= JOBCTL_STOP_CONSUME;
394 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
395 return;
396
397 /* Have the new thread join an on-going signal group stop */
398 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
399}
400
401static struct ucounts *sig_get_ucounts(struct task_struct *t, int sig,
402 int override_rlimit)
403{
404 struct ucounts *ucounts;
405 long sigpending;
406
407 /*
408 * Protect access to @t credentials. This can go away when all
409 * callers hold rcu read lock.
410 *
411 * NOTE! A pending signal will hold on to the user refcount,
412 * and we get/put the refcount only when the sigpending count
413 * changes from/to zero.
414 */
415 rcu_read_lock();
416 ucounts = task_ucounts(t);
417 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING,
418 override_rlimit);
419 rcu_read_unlock();
420 if (!sigpending)
421 return NULL;
422
423 if (unlikely(!override_rlimit && sigpending > task_rlimit(t, RLIMIT_SIGPENDING))) {
424 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
425 print_dropped_signal(sig);
426 return NULL;
427 }
428
429 return ucounts;
430}
431
432static void __sigqueue_init(struct sigqueue *q, struct ucounts *ucounts,
433 const unsigned int sigqueue_flags)
434{
435 INIT_LIST_HEAD(&q->list);
436 q->flags = sigqueue_flags;
437 q->ucounts = ucounts;
438}
439
440/*
441 * allocate a new signal queue record
442 * - this may be called without locks if and only if t == current, otherwise an
443 * appropriate lock must be held to stop the target task from exiting
444 */
445static struct sigqueue *sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
446 int override_rlimit)
447{
448 struct ucounts *ucounts = sig_get_ucounts(t, sig, override_rlimit);
449 struct sigqueue *q;
450
451 if (!ucounts)
452 return NULL;
453
454 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
455 if (!q) {
456 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
457 return NULL;
458 }
459
460 __sigqueue_init(q, ucounts, 0);
461 return q;
462}
463
464static void __sigqueue_free(struct sigqueue *q)
465{
466 if (q->flags & SIGQUEUE_PREALLOC) {
467 posixtimer_sigqueue_putref(q);
468 return;
469 }
470 if (q->ucounts) {
471 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
472 q->ucounts = NULL;
473 }
474 kmem_cache_free(sigqueue_cachep, q);
475}
476
477void flush_sigqueue(struct sigpending *queue)
478{
479 struct sigqueue *q;
480
481 sigemptyset(&queue->signal);
482 while (!list_empty(&queue->list)) {
483 q = list_entry(queue->list.next, struct sigqueue , list);
484 list_del_init(&q->list);
485 __sigqueue_free(q);
486 }
487}
488
489/*
490 * Flush all pending signals for this kthread.
491 */
492void flush_signals(struct task_struct *t)
493{
494 unsigned long flags;
495
496 spin_lock_irqsave(&t->sighand->siglock, flags);
497 clear_tsk_thread_flag(t, TIF_SIGPENDING);
498 flush_sigqueue(&t->pending);
499 flush_sigqueue(&t->signal->shared_pending);
500 spin_unlock_irqrestore(&t->sighand->siglock, flags);
501}
502EXPORT_SYMBOL(flush_signals);
503
504void ignore_signals(struct task_struct *t)
505{
506 int i;
507
508 for (i = 0; i < _NSIG; ++i)
509 t->sighand->action[i].sa.sa_handler = SIG_IGN;
510
511 flush_signals(t);
512}
513
514/*
515 * Flush all handlers for a task.
516 */
517
518void
519flush_signal_handlers(struct task_struct *t, int force_default)
520{
521 int i;
522 struct k_sigaction *ka = &t->sighand->action[0];
523 for (i = _NSIG ; i != 0 ; i--) {
524 if (force_default || ka->sa.sa_handler != SIG_IGN)
525 ka->sa.sa_handler = SIG_DFL;
526 ka->sa.sa_flags = 0;
527#ifdef __ARCH_HAS_SA_RESTORER
528 ka->sa.sa_restorer = NULL;
529#endif
530 sigemptyset(&ka->sa.sa_mask);
531 ka++;
532 }
533}
534
535bool unhandled_signal(struct task_struct *tsk, int sig)
536{
537 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
538 if (is_global_init(tsk))
539 return true;
540
541 if (handler != SIG_IGN && handler != SIG_DFL)
542 return false;
543
544 /* If dying, we handle all new signals by ignoring them */
545 if (fatal_signal_pending(tsk))
546 return false;
547
548 /* if ptraced, let the tracer determine */
549 return !tsk->ptrace;
550}
551
552static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
553 struct sigqueue **timer_sigq)
554{
555 struct sigqueue *q, *first = NULL;
556
557 /*
558 * Collect the siginfo appropriate to this signal. Check if
559 * there is another siginfo for the same signal.
560 */
561 list_for_each_entry(q, &list->list, list) {
562 if (q->info.si_signo == sig) {
563 if (first)
564 goto still_pending;
565 first = q;
566 }
567 }
568
569 sigdelset(&list->signal, sig);
570
571 if (first) {
572still_pending:
573 list_del_init(&first->list);
574 copy_siginfo(info, &first->info);
575
576 /*
577 * posix-timer signals are preallocated and freed when the last
578 * reference count is dropped in posixtimer_deliver_signal() or
579 * immediately on timer deletion when the signal is not pending.
580 * Spare the extra round through __sigqueue_free() which is
581 * ignoring preallocated signals.
582 */
583 if (unlikely((first->flags & SIGQUEUE_PREALLOC) && (info->si_code == SI_TIMER)))
584 *timer_sigq = first;
585 else
586 __sigqueue_free(first);
587 } else {
588 /*
589 * Ok, it wasn't in the queue. This must be
590 * a fast-pathed signal or we must have been
591 * out of queue space. So zero out the info.
592 */
593 clear_siginfo(info);
594 info->si_signo = sig;
595 info->si_errno = 0;
596 info->si_code = SI_USER;
597 info->si_pid = 0;
598 info->si_uid = 0;
599 }
600}
601
602static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
603 kernel_siginfo_t *info, struct sigqueue **timer_sigq)
604{
605 int sig = next_signal(pending, mask);
606
607 if (sig)
608 collect_signal(sig, pending, info, timer_sigq);
609 return sig;
610}
611
612/*
613 * Try to dequeue a signal. If a deliverable signal is found fill in the
614 * caller provided siginfo and return the signal number. Otherwise return
615 * 0.
616 */
617int dequeue_signal(sigset_t *mask, kernel_siginfo_t *info, enum pid_type *type)
618{
619 struct task_struct *tsk = current;
620 struct sigqueue *timer_sigq;
621 int signr;
622
623 lockdep_assert_held(&tsk->sighand->siglock);
624
625again:
626 *type = PIDTYPE_PID;
627 timer_sigq = NULL;
628 signr = __dequeue_signal(&tsk->pending, mask, info, &timer_sigq);
629 if (!signr) {
630 *type = PIDTYPE_TGID;
631 signr = __dequeue_signal(&tsk->signal->shared_pending,
632 mask, info, &timer_sigq);
633
634 if (unlikely(signr == SIGALRM))
635 posixtimer_rearm_itimer(tsk);
636 }
637
638 recalc_sigpending();
639 if (!signr)
640 return 0;
641
642 if (unlikely(sig_kernel_stop(signr))) {
643 /*
644 * Set a marker that we have dequeued a stop signal. Our
645 * caller might release the siglock and then the pending
646 * stop signal it is about to process is no longer in the
647 * pending bitmasks, but must still be cleared by a SIGCONT
648 * (and overruled by a SIGKILL). So those cases clear this
649 * shared flag after we've set it. Note that this flag may
650 * remain set after the signal we return is ignored or
651 * handled. That doesn't matter because its only purpose
652 * is to alert stop-signal processing code when another
653 * processor has come along and cleared the flag.
654 */
655 current->jobctl |= JOBCTL_STOP_DEQUEUED;
656 }
657
658 if (IS_ENABLED(CONFIG_POSIX_TIMERS) && unlikely(timer_sigq)) {
659 if (!posixtimer_deliver_signal(info, timer_sigq))
660 goto again;
661 }
662
663 return signr;
664}
665EXPORT_SYMBOL_GPL(dequeue_signal);
666
667static int dequeue_synchronous_signal(kernel_siginfo_t *info)
668{
669 struct task_struct *tsk = current;
670 struct sigpending *pending = &tsk->pending;
671 struct sigqueue *q, *sync = NULL;
672
673 /*
674 * Might a synchronous signal be in the queue?
675 */
676 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
677 return 0;
678
679 /*
680 * Return the first synchronous signal in the queue.
681 */
682 list_for_each_entry(q, &pending->list, list) {
683 /* Synchronous signals have a positive si_code */
684 if ((q->info.si_code > SI_USER) &&
685 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
686 sync = q;
687 goto next;
688 }
689 }
690 return 0;
691next:
692 /*
693 * Check if there is another siginfo for the same signal.
694 */
695 list_for_each_entry_continue(q, &pending->list, list) {
696 if (q->info.si_signo == sync->info.si_signo)
697 goto still_pending;
698 }
699
700 sigdelset(&pending->signal, sync->info.si_signo);
701 recalc_sigpending();
702still_pending:
703 list_del_init(&sync->list);
704 copy_siginfo(info, &sync->info);
705 __sigqueue_free(sync);
706 return info->si_signo;
707}
708
709/*
710 * Tell a process that it has a new active signal..
711 *
712 * NOTE! we rely on the previous spin_lock to
713 * lock interrupts for us! We can only be called with
714 * "siglock" held, and the local interrupt must
715 * have been disabled when that got acquired!
716 *
717 * No need to set need_resched since signal event passing
718 * goes through ->blocked
719 */
720void signal_wake_up_state(struct task_struct *t, unsigned int state)
721{
722 lockdep_assert_held(&t->sighand->siglock);
723
724 set_tsk_thread_flag(t, TIF_SIGPENDING);
725
726 /*
727 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
728 * case. We don't check t->state here because there is a race with it
729 * executing another processor and just now entering stopped state.
730 * By using wake_up_state, we ensure the process will wake up and
731 * handle its death signal.
732 */
733 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
734 kick_process(t);
735}
736
737static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q);
738
739static void sigqueue_free_ignored(struct task_struct *tsk, struct sigqueue *q)
740{
741 if (likely(!(q->flags & SIGQUEUE_PREALLOC) || q->info.si_code != SI_TIMER))
742 __sigqueue_free(q);
743 else
744 posixtimer_sig_ignore(tsk, q);
745}
746
747/* Remove signals in mask from the pending set and queue. */
748static void flush_sigqueue_mask(struct task_struct *p, sigset_t *mask, struct sigpending *s)
749{
750 struct sigqueue *q, *n;
751 sigset_t m;
752
753 lockdep_assert_held(&p->sighand->siglock);
754
755 sigandsets(&m, mask, &s->signal);
756 if (sigisemptyset(&m))
757 return;
758
759 sigandnsets(&s->signal, &s->signal, mask);
760 list_for_each_entry_safe(q, n, &s->list, list) {
761 if (sigismember(mask, q->info.si_signo)) {
762 list_del_init(&q->list);
763 sigqueue_free_ignored(p, q);
764 }
765 }
766}
767
768static inline int is_si_special(const struct kernel_siginfo *info)
769{
770 return info <= SEND_SIG_PRIV;
771}
772
773static inline bool si_fromuser(const struct kernel_siginfo *info)
774{
775 return info == SEND_SIG_NOINFO ||
776 (!is_si_special(info) && SI_FROMUSER(info));
777}
778
779/*
780 * called with RCU read lock from check_kill_permission()
781 */
782static bool kill_ok_by_cred(struct task_struct *t)
783{
784 const struct cred *cred = current_cred();
785 const struct cred *tcred = __task_cred(t);
786
787 return uid_eq(cred->euid, tcred->suid) ||
788 uid_eq(cred->euid, tcred->uid) ||
789 uid_eq(cred->uid, tcred->suid) ||
790 uid_eq(cred->uid, tcred->uid) ||
791 ns_capable(tcred->user_ns, CAP_KILL);
792}
793
794/*
795 * Bad permissions for sending the signal
796 * - the caller must hold the RCU read lock
797 */
798static int check_kill_permission(int sig, struct kernel_siginfo *info,
799 struct task_struct *t)
800{
801 struct pid *sid;
802 int error;
803
804 if (!valid_signal(sig))
805 return -EINVAL;
806
807 if (!si_fromuser(info))
808 return 0;
809
810 error = audit_signal_info(sig, t); /* Let audit system see the signal */
811 if (error)
812 return error;
813
814 if (!same_thread_group(current, t) &&
815 !kill_ok_by_cred(t)) {
816 switch (sig) {
817 case SIGCONT:
818 sid = task_session(t);
819 /*
820 * We don't return the error if sid == NULL. The
821 * task was unhashed, the caller must notice this.
822 */
823 if (!sid || sid == task_session(current))
824 break;
825 fallthrough;
826 default:
827 return -EPERM;
828 }
829 }
830
831 return security_task_kill(t, info, sig, NULL);
832}
833
834/**
835 * ptrace_trap_notify - schedule trap to notify ptracer
836 * @t: tracee wanting to notify tracer
837 *
838 * This function schedules sticky ptrace trap which is cleared on the next
839 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
840 * ptracer.
841 *
842 * If @t is running, STOP trap will be taken. If trapped for STOP and
843 * ptracer is listening for events, tracee is woken up so that it can
844 * re-trap for the new event. If trapped otherwise, STOP trap will be
845 * eventually taken without returning to userland after the existing traps
846 * are finished by PTRACE_CONT.
847 *
848 * CONTEXT:
849 * Must be called with @task->sighand->siglock held.
850 */
851static void ptrace_trap_notify(struct task_struct *t)
852{
853 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
854 lockdep_assert_held(&t->sighand->siglock);
855
856 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
857 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
858}
859
860/*
861 * Handle magic process-wide effects of stop/continue signals. Unlike
862 * the signal actions, these happen immediately at signal-generation
863 * time regardless of blocking, ignoring, or handling. This does the
864 * actual continuing for SIGCONT, but not the actual stopping for stop
865 * signals. The process stop is done as a signal action for SIG_DFL.
866 *
867 * Returns true if the signal should be actually delivered, otherwise
868 * it should be dropped.
869 */
870static bool prepare_signal(int sig, struct task_struct *p, bool force)
871{
872 struct signal_struct *signal = p->signal;
873 struct task_struct *t;
874 sigset_t flush;
875
876 if (signal->flags & SIGNAL_GROUP_EXIT) {
877 if (signal->core_state)
878 return sig == SIGKILL;
879 /*
880 * The process is in the middle of dying, drop the signal.
881 */
882 return false;
883 } else if (sig_kernel_stop(sig)) {
884 /*
885 * This is a stop signal. Remove SIGCONT from all queues.
886 */
887 siginitset(&flush, sigmask(SIGCONT));
888 flush_sigqueue_mask(p, &flush, &signal->shared_pending);
889 for_each_thread(p, t)
890 flush_sigqueue_mask(p, &flush, &t->pending);
891 } else if (sig == SIGCONT) {
892 unsigned int why;
893 /*
894 * Remove all stop signals from all queues, wake all threads.
895 */
896 siginitset(&flush, SIG_KERNEL_STOP_MASK);
897 flush_sigqueue_mask(p, &flush, &signal->shared_pending);
898 for_each_thread(p, t) {
899 flush_sigqueue_mask(p, &flush, &t->pending);
900 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
901 if (likely(!(t->ptrace & PT_SEIZED))) {
902 t->jobctl &= ~JOBCTL_STOPPED;
903 wake_up_state(t, __TASK_STOPPED);
904 } else
905 ptrace_trap_notify(t);
906 }
907
908 /*
909 * Notify the parent with CLD_CONTINUED if we were stopped.
910 *
911 * If we were in the middle of a group stop, we pretend it
912 * was already finished, and then continued. Since SIGCHLD
913 * doesn't queue we report only CLD_STOPPED, as if the next
914 * CLD_CONTINUED was dropped.
915 */
916 why = 0;
917 if (signal->flags & SIGNAL_STOP_STOPPED)
918 why |= SIGNAL_CLD_CONTINUED;
919 else if (signal->group_stop_count)
920 why |= SIGNAL_CLD_STOPPED;
921
922 if (why) {
923 /*
924 * The first thread which returns from do_signal_stop()
925 * will take ->siglock, notice SIGNAL_CLD_MASK, and
926 * notify its parent. See get_signal().
927 */
928 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
929 signal->group_stop_count = 0;
930 signal->group_exit_code = 0;
931 }
932 }
933
934 return !sig_ignored(p, sig, force);
935}
936
937/*
938 * Test if P wants to take SIG. After we've checked all threads with this,
939 * it's equivalent to finding no threads not blocking SIG. Any threads not
940 * blocking SIG were ruled out because they are not running and already
941 * have pending signals. Such threads will dequeue from the shared queue
942 * as soon as they're available, so putting the signal on the shared queue
943 * will be equivalent to sending it to one such thread.
944 */
945static inline bool wants_signal(int sig, struct task_struct *p)
946{
947 if (sigismember(&p->blocked, sig))
948 return false;
949
950 if (p->flags & PF_EXITING)
951 return false;
952
953 if (sig == SIGKILL)
954 return true;
955
956 if (task_is_stopped_or_traced(p))
957 return false;
958
959 return task_curr(p) || !task_sigpending(p);
960}
961
962static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
963{
964 struct signal_struct *signal = p->signal;
965 struct task_struct *t;
966
967 /*
968 * Now find a thread we can wake up to take the signal off the queue.
969 *
970 * Try the suggested task first (may or may not be the main thread).
971 */
972 if (wants_signal(sig, p))
973 t = p;
974 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
975 /*
976 * There is just one thread and it does not need to be woken.
977 * It will dequeue unblocked signals before it runs again.
978 */
979 return;
980 else {
981 /*
982 * Otherwise try to find a suitable thread.
983 */
984 t = signal->curr_target;
985 while (!wants_signal(sig, t)) {
986 t = next_thread(t);
987 if (t == signal->curr_target)
988 /*
989 * No thread needs to be woken.
990 * Any eligible threads will see
991 * the signal in the queue soon.
992 */
993 return;
994 }
995 signal->curr_target = t;
996 }
997
998 /*
999 * Found a killable thread. If the signal will be fatal,
1000 * then start taking the whole group down immediately.
1001 */
1002 if (sig_fatal(p, sig) &&
1003 (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1004 !sigismember(&t->real_blocked, sig) &&
1005 (sig == SIGKILL || !p->ptrace)) {
1006 /*
1007 * This signal will be fatal to the whole group.
1008 */
1009 if (!sig_kernel_coredump(sig)) {
1010 /*
1011 * Start a group exit and wake everybody up.
1012 * This way we don't have other threads
1013 * running and doing things after a slower
1014 * thread has the fatal signal pending.
1015 */
1016 signal->flags = SIGNAL_GROUP_EXIT;
1017 signal->group_exit_code = sig;
1018 signal->group_stop_count = 0;
1019 __for_each_thread(signal, t) {
1020 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1021 sigaddset(&t->pending.signal, SIGKILL);
1022 signal_wake_up(t, 1);
1023 }
1024 return;
1025 }
1026 }
1027
1028 /*
1029 * The signal is already in the shared-pending queue.
1030 * Tell the chosen thread to wake up and dequeue it.
1031 */
1032 signal_wake_up(t, sig == SIGKILL);
1033 return;
1034}
1035
1036static inline bool legacy_queue(struct sigpending *signals, int sig)
1037{
1038 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1039}
1040
1041static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1042 struct task_struct *t, enum pid_type type, bool force)
1043{
1044 struct sigpending *pending;
1045 struct sigqueue *q;
1046 int override_rlimit;
1047 int ret = 0, result;
1048
1049 lockdep_assert_held(&t->sighand->siglock);
1050
1051 result = TRACE_SIGNAL_IGNORED;
1052 if (!prepare_signal(sig, t, force))
1053 goto ret;
1054
1055 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1056 /*
1057 * Short-circuit ignored signals and support queuing
1058 * exactly one non-rt signal, so that we can get more
1059 * detailed information about the cause of the signal.
1060 */
1061 result = TRACE_SIGNAL_ALREADY_PENDING;
1062 if (legacy_queue(pending, sig))
1063 goto ret;
1064
1065 result = TRACE_SIGNAL_DELIVERED;
1066 /*
1067 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1068 */
1069 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1070 goto out_set;
1071
1072 /*
1073 * Real-time signals must be queued if sent by sigqueue, or
1074 * some other real-time mechanism. It is implementation
1075 * defined whether kill() does so. We attempt to do so, on
1076 * the principle of least surprise, but since kill is not
1077 * allowed to fail with EAGAIN when low on memory we just
1078 * make sure at least one signal gets delivered and don't
1079 * pass on the info struct.
1080 */
1081 if (sig < SIGRTMIN)
1082 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1083 else
1084 override_rlimit = 0;
1085
1086 q = sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1087
1088 if (q) {
1089 list_add_tail(&q->list, &pending->list);
1090 switch ((unsigned long) info) {
1091 case (unsigned long) SEND_SIG_NOINFO:
1092 clear_siginfo(&q->info);
1093 q->info.si_signo = sig;
1094 q->info.si_errno = 0;
1095 q->info.si_code = SI_USER;
1096 q->info.si_pid = task_tgid_nr_ns(current,
1097 task_active_pid_ns(t));
1098 rcu_read_lock();
1099 q->info.si_uid =
1100 from_kuid_munged(task_cred_xxx(t, user_ns),
1101 current_uid());
1102 rcu_read_unlock();
1103 break;
1104 case (unsigned long) SEND_SIG_PRIV:
1105 clear_siginfo(&q->info);
1106 q->info.si_signo = sig;
1107 q->info.si_errno = 0;
1108 q->info.si_code = SI_KERNEL;
1109 q->info.si_pid = 0;
1110 q->info.si_uid = 0;
1111 break;
1112 default:
1113 copy_siginfo(&q->info, info);
1114 break;
1115 }
1116 } else if (!is_si_special(info) &&
1117 sig >= SIGRTMIN && info->si_code != SI_USER) {
1118 /*
1119 * Queue overflow, abort. We may abort if the
1120 * signal was rt and sent by user using something
1121 * other than kill().
1122 */
1123 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1124 ret = -EAGAIN;
1125 goto ret;
1126 } else {
1127 /*
1128 * This is a silent loss of information. We still
1129 * send the signal, but the *info bits are lost.
1130 */
1131 result = TRACE_SIGNAL_LOSE_INFO;
1132 }
1133
1134out_set:
1135 signalfd_notify(t, sig);
1136 sigaddset(&pending->signal, sig);
1137
1138 /* Let multiprocess signals appear after on-going forks */
1139 if (type > PIDTYPE_TGID) {
1140 struct multiprocess_signals *delayed;
1141 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1142 sigset_t *signal = &delayed->signal;
1143 /* Can't queue both a stop and a continue signal */
1144 if (sig == SIGCONT)
1145 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1146 else if (sig_kernel_stop(sig))
1147 sigdelset(signal, SIGCONT);
1148 sigaddset(signal, sig);
1149 }
1150 }
1151
1152 complete_signal(sig, t, type);
1153ret:
1154 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1155 return ret;
1156}
1157
1158static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1159{
1160 bool ret = false;
1161 switch (siginfo_layout(info->si_signo, info->si_code)) {
1162 case SIL_KILL:
1163 case SIL_CHLD:
1164 case SIL_RT:
1165 ret = true;
1166 break;
1167 case SIL_TIMER:
1168 case SIL_POLL:
1169 case SIL_FAULT:
1170 case SIL_FAULT_TRAPNO:
1171 case SIL_FAULT_MCEERR:
1172 case SIL_FAULT_BNDERR:
1173 case SIL_FAULT_PKUERR:
1174 case SIL_FAULT_PERF_EVENT:
1175 case SIL_SYS:
1176 ret = false;
1177 break;
1178 }
1179 return ret;
1180}
1181
1182int send_signal_locked(int sig, struct kernel_siginfo *info,
1183 struct task_struct *t, enum pid_type type)
1184{
1185 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1186 bool force = false;
1187
1188 if (info == SEND_SIG_NOINFO) {
1189 /* Force if sent from an ancestor pid namespace */
1190 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1191 } else if (info == SEND_SIG_PRIV) {
1192 /* Don't ignore kernel generated signals */
1193 force = true;
1194 } else if (has_si_pid_and_uid(info)) {
1195 /* SIGKILL and SIGSTOP is special or has ids */
1196 struct user_namespace *t_user_ns;
1197
1198 rcu_read_lock();
1199 t_user_ns = task_cred_xxx(t, user_ns);
1200 if (current_user_ns() != t_user_ns) {
1201 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1202 info->si_uid = from_kuid_munged(t_user_ns, uid);
1203 }
1204 rcu_read_unlock();
1205
1206 /* A kernel generated signal? */
1207 force = (info->si_code == SI_KERNEL);
1208
1209 /* From an ancestor pid namespace? */
1210 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1211 info->si_pid = 0;
1212 force = true;
1213 }
1214 }
1215 return __send_signal_locked(sig, info, t, type, force);
1216}
1217
1218static void print_fatal_signal(int signr)
1219{
1220 struct pt_regs *regs = task_pt_regs(current);
1221 struct file *exe_file;
1222
1223 exe_file = get_task_exe_file(current);
1224 if (exe_file) {
1225 pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1226 exe_file, current->comm, signr);
1227 fput(exe_file);
1228 } else {
1229 pr_info("%s: potentially unexpected fatal signal %d.\n",
1230 current->comm, signr);
1231 }
1232
1233#if defined(__i386__) && !defined(__arch_um__)
1234 pr_info("code at %08lx: ", regs->ip);
1235 {
1236 int i;
1237 for (i = 0; i < 16; i++) {
1238 unsigned char insn;
1239
1240 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1241 break;
1242 pr_cont("%02x ", insn);
1243 }
1244 }
1245 pr_cont("\n");
1246#endif
1247 preempt_disable();
1248 show_regs(regs);
1249 preempt_enable();
1250}
1251
1252static int __init setup_print_fatal_signals(char *str)
1253{
1254 get_option (&str, &print_fatal_signals);
1255
1256 return 1;
1257}
1258
1259__setup("print-fatal-signals=", setup_print_fatal_signals);
1260
1261int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1262 enum pid_type type)
1263{
1264 unsigned long flags;
1265 int ret = -ESRCH;
1266
1267 if (lock_task_sighand(p, &flags)) {
1268 ret = send_signal_locked(sig, info, p, type);
1269 unlock_task_sighand(p, &flags);
1270 }
1271
1272 return ret;
1273}
1274
1275enum sig_handler {
1276 HANDLER_CURRENT, /* If reachable use the current handler */
1277 HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1278 HANDLER_EXIT, /* Only visible as the process exit code */
1279};
1280
1281/*
1282 * Force a signal that the process can't ignore: if necessary
1283 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1284 *
1285 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1286 * since we do not want to have a signal handler that was blocked
1287 * be invoked when user space had explicitly blocked it.
1288 *
1289 * We don't want to have recursive SIGSEGV's etc, for example,
1290 * that is why we also clear SIGNAL_UNKILLABLE.
1291 */
1292static int
1293force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1294 enum sig_handler handler)
1295{
1296 unsigned long int flags;
1297 int ret, blocked, ignored;
1298 struct k_sigaction *action;
1299 int sig = info->si_signo;
1300
1301 spin_lock_irqsave(&t->sighand->siglock, flags);
1302 action = &t->sighand->action[sig-1];
1303 ignored = action->sa.sa_handler == SIG_IGN;
1304 blocked = sigismember(&t->blocked, sig);
1305 if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1306 action->sa.sa_handler = SIG_DFL;
1307 if (handler == HANDLER_EXIT)
1308 action->sa.sa_flags |= SA_IMMUTABLE;
1309 if (blocked)
1310 sigdelset(&t->blocked, sig);
1311 }
1312 /*
1313 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1314 * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1315 */
1316 if (action->sa.sa_handler == SIG_DFL &&
1317 (!t->ptrace || (handler == HANDLER_EXIT)))
1318 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1319 ret = send_signal_locked(sig, info, t, PIDTYPE_PID);
1320 /* This can happen if the signal was already pending and blocked */
1321 if (!task_sigpending(t))
1322 signal_wake_up(t, 0);
1323 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1324
1325 return ret;
1326}
1327
1328int force_sig_info(struct kernel_siginfo *info)
1329{
1330 return force_sig_info_to_task(info, current, HANDLER_CURRENT);
1331}
1332
1333/*
1334 * Nuke all other threads in the group.
1335 */
1336int zap_other_threads(struct task_struct *p)
1337{
1338 struct task_struct *t;
1339 int count = 0;
1340
1341 p->signal->group_stop_count = 0;
1342
1343 for_other_threads(p, t) {
1344 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1345 count++;
1346
1347 /* Don't bother with already dead threads */
1348 if (t->exit_state)
1349 continue;
1350 sigaddset(&t->pending.signal, SIGKILL);
1351 signal_wake_up(t, 1);
1352 }
1353
1354 return count;
1355}
1356
1357struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1358 unsigned long *flags)
1359{
1360 struct sighand_struct *sighand;
1361
1362 rcu_read_lock();
1363 for (;;) {
1364 sighand = rcu_dereference(tsk->sighand);
1365 if (unlikely(sighand == NULL))
1366 break;
1367
1368 /*
1369 * This sighand can be already freed and even reused, but
1370 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1371 * initializes ->siglock: this slab can't go away, it has
1372 * the same object type, ->siglock can't be reinitialized.
1373 *
1374 * We need to ensure that tsk->sighand is still the same
1375 * after we take the lock, we can race with de_thread() or
1376 * __exit_signal(). In the latter case the next iteration
1377 * must see ->sighand == NULL.
1378 */
1379 spin_lock_irqsave(&sighand->siglock, *flags);
1380 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1381 break;
1382 spin_unlock_irqrestore(&sighand->siglock, *flags);
1383 }
1384 rcu_read_unlock();
1385
1386 return sighand;
1387}
1388
1389#ifdef CONFIG_LOCKDEP
1390void lockdep_assert_task_sighand_held(struct task_struct *task)
1391{
1392 struct sighand_struct *sighand;
1393
1394 rcu_read_lock();
1395 sighand = rcu_dereference(task->sighand);
1396 if (sighand)
1397 lockdep_assert_held(&sighand->siglock);
1398 else
1399 WARN_ON_ONCE(1);
1400 rcu_read_unlock();
1401}
1402#endif
1403
1404/*
1405 * send signal info to all the members of a thread group or to the
1406 * individual thread if type == PIDTYPE_PID.
1407 */
1408int group_send_sig_info(int sig, struct kernel_siginfo *info,
1409 struct task_struct *p, enum pid_type type)
1410{
1411 int ret;
1412
1413 rcu_read_lock();
1414 ret = check_kill_permission(sig, info, p);
1415 rcu_read_unlock();
1416
1417 if (!ret && sig)
1418 ret = do_send_sig_info(sig, info, p, type);
1419
1420 return ret;
1421}
1422
1423/*
1424 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1425 * control characters do (^C, ^Z etc)
1426 * - the caller must hold at least a readlock on tasklist_lock
1427 */
1428int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1429{
1430 struct task_struct *p = NULL;
1431 int ret = -ESRCH;
1432
1433 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1434 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1435 /*
1436 * If group_send_sig_info() succeeds at least once ret
1437 * becomes 0 and after that the code below has no effect.
1438 * Otherwise we return the last err or -ESRCH if this
1439 * process group is empty.
1440 */
1441 if (ret)
1442 ret = err;
1443 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1444
1445 return ret;
1446}
1447
1448static int kill_pid_info_type(int sig, struct kernel_siginfo *info,
1449 struct pid *pid, enum pid_type type)
1450{
1451 int error = -ESRCH;
1452 struct task_struct *p;
1453
1454 for (;;) {
1455 rcu_read_lock();
1456 p = pid_task(pid, PIDTYPE_PID);
1457 if (p)
1458 error = group_send_sig_info(sig, info, p, type);
1459 rcu_read_unlock();
1460 if (likely(!p || error != -ESRCH))
1461 return error;
1462 /*
1463 * The task was unhashed in between, try again. If it
1464 * is dead, pid_task() will return NULL, if we race with
1465 * de_thread() it will find the new leader.
1466 */
1467 }
1468}
1469
1470int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1471{
1472 return kill_pid_info_type(sig, info, pid, PIDTYPE_TGID);
1473}
1474
1475static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1476{
1477 int error;
1478 rcu_read_lock();
1479 error = kill_pid_info(sig, info, find_vpid(pid));
1480 rcu_read_unlock();
1481 return error;
1482}
1483
1484static inline bool kill_as_cred_perm(const struct cred *cred,
1485 struct task_struct *target)
1486{
1487 const struct cred *pcred = __task_cred(target);
1488
1489 return uid_eq(cred->euid, pcred->suid) ||
1490 uid_eq(cred->euid, pcred->uid) ||
1491 uid_eq(cred->uid, pcred->suid) ||
1492 uid_eq(cred->uid, pcred->uid);
1493}
1494
1495/*
1496 * The usb asyncio usage of siginfo is wrong. The glibc support
1497 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1498 * AKA after the generic fields:
1499 * kernel_pid_t si_pid;
1500 * kernel_uid32_t si_uid;
1501 * sigval_t si_value;
1502 *
1503 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1504 * after the generic fields is:
1505 * void __user *si_addr;
1506 *
1507 * This is a practical problem when there is a 64bit big endian kernel
1508 * and a 32bit userspace. As the 32bit address will encoded in the low
1509 * 32bits of the pointer. Those low 32bits will be stored at higher
1510 * address than appear in a 32 bit pointer. So userspace will not
1511 * see the address it was expecting for it's completions.
1512 *
1513 * There is nothing in the encoding that can allow
1514 * copy_siginfo_to_user32 to detect this confusion of formats, so
1515 * handle this by requiring the caller of kill_pid_usb_asyncio to
1516 * notice when this situration takes place and to store the 32bit
1517 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1518 * parameter.
1519 */
1520int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1521 struct pid *pid, const struct cred *cred)
1522{
1523 struct kernel_siginfo info;
1524 struct task_struct *p;
1525 unsigned long flags;
1526 int ret = -EINVAL;
1527
1528 if (!valid_signal(sig))
1529 return ret;
1530
1531 clear_siginfo(&info);
1532 info.si_signo = sig;
1533 info.si_errno = errno;
1534 info.si_code = SI_ASYNCIO;
1535 *((sigval_t *)&info.si_pid) = addr;
1536
1537 rcu_read_lock();
1538 p = pid_task(pid, PIDTYPE_PID);
1539 if (!p) {
1540 ret = -ESRCH;
1541 goto out_unlock;
1542 }
1543 if (!kill_as_cred_perm(cred, p)) {
1544 ret = -EPERM;
1545 goto out_unlock;
1546 }
1547 ret = security_task_kill(p, &info, sig, cred);
1548 if (ret)
1549 goto out_unlock;
1550
1551 if (sig) {
1552 if (lock_task_sighand(p, &flags)) {
1553 ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false);
1554 unlock_task_sighand(p, &flags);
1555 } else
1556 ret = -ESRCH;
1557 }
1558out_unlock:
1559 rcu_read_unlock();
1560 return ret;
1561}
1562EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1563
1564/*
1565 * kill_something_info() interprets pid in interesting ways just like kill(2).
1566 *
1567 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1568 * is probably wrong. Should make it like BSD or SYSV.
1569 */
1570
1571static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1572{
1573 int ret;
1574
1575 if (pid > 0)
1576 return kill_proc_info(sig, info, pid);
1577
1578 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1579 if (pid == INT_MIN)
1580 return -ESRCH;
1581
1582 read_lock(&tasklist_lock);
1583 if (pid != -1) {
1584 ret = __kill_pgrp_info(sig, info,
1585 pid ? find_vpid(-pid) : task_pgrp(current));
1586 } else {
1587 int retval = 0, count = 0;
1588 struct task_struct * p;
1589
1590 for_each_process(p) {
1591 if (task_pid_vnr(p) > 1 &&
1592 !same_thread_group(p, current)) {
1593 int err = group_send_sig_info(sig, info, p,
1594 PIDTYPE_MAX);
1595 ++count;
1596 if (err != -EPERM)
1597 retval = err;
1598 }
1599 }
1600 ret = count ? retval : -ESRCH;
1601 }
1602 read_unlock(&tasklist_lock);
1603
1604 return ret;
1605}
1606
1607/*
1608 * These are for backward compatibility with the rest of the kernel source.
1609 */
1610
1611int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1612{
1613 /*
1614 * Make sure legacy kernel users don't send in bad values
1615 * (normal paths check this in check_kill_permission).
1616 */
1617 if (!valid_signal(sig))
1618 return -EINVAL;
1619
1620 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1621}
1622EXPORT_SYMBOL(send_sig_info);
1623
1624#define __si_special(priv) \
1625 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1626
1627int
1628send_sig(int sig, struct task_struct *p, int priv)
1629{
1630 return send_sig_info(sig, __si_special(priv), p);
1631}
1632EXPORT_SYMBOL(send_sig);
1633
1634void force_sig(int sig)
1635{
1636 struct kernel_siginfo info;
1637
1638 clear_siginfo(&info);
1639 info.si_signo = sig;
1640 info.si_errno = 0;
1641 info.si_code = SI_KERNEL;
1642 info.si_pid = 0;
1643 info.si_uid = 0;
1644 force_sig_info(&info);
1645}
1646EXPORT_SYMBOL(force_sig);
1647
1648void force_fatal_sig(int sig)
1649{
1650 struct kernel_siginfo info;
1651
1652 clear_siginfo(&info);
1653 info.si_signo = sig;
1654 info.si_errno = 0;
1655 info.si_code = SI_KERNEL;
1656 info.si_pid = 0;
1657 info.si_uid = 0;
1658 force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
1659}
1660
1661void force_exit_sig(int sig)
1662{
1663 struct kernel_siginfo info;
1664
1665 clear_siginfo(&info);
1666 info.si_signo = sig;
1667 info.si_errno = 0;
1668 info.si_code = SI_KERNEL;
1669 info.si_pid = 0;
1670 info.si_uid = 0;
1671 force_sig_info_to_task(&info, current, HANDLER_EXIT);
1672}
1673
1674/*
1675 * When things go south during signal handling, we
1676 * will force a SIGSEGV. And if the signal that caused
1677 * the problem was already a SIGSEGV, we'll want to
1678 * make sure we don't even try to deliver the signal..
1679 */
1680void force_sigsegv(int sig)
1681{
1682 if (sig == SIGSEGV)
1683 force_fatal_sig(SIGSEGV);
1684 else
1685 force_sig(SIGSEGV);
1686}
1687
1688int force_sig_fault_to_task(int sig, int code, void __user *addr,
1689 struct task_struct *t)
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 = code;
1697 info.si_addr = addr;
1698 return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
1699}
1700
1701int force_sig_fault(int sig, int code, void __user *addr)
1702{
1703 return force_sig_fault_to_task(sig, code, addr, current);
1704}
1705
1706int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t)
1707{
1708 struct kernel_siginfo info;
1709
1710 clear_siginfo(&info);
1711 info.si_signo = sig;
1712 info.si_errno = 0;
1713 info.si_code = code;
1714 info.si_addr = addr;
1715 return send_sig_info(info.si_signo, &info, t);
1716}
1717
1718int force_sig_mceerr(int code, void __user *addr, short lsb)
1719{
1720 struct kernel_siginfo info;
1721
1722 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1723 clear_siginfo(&info);
1724 info.si_signo = SIGBUS;
1725 info.si_errno = 0;
1726 info.si_code = code;
1727 info.si_addr = addr;
1728 info.si_addr_lsb = lsb;
1729 return force_sig_info(&info);
1730}
1731
1732int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1733{
1734 struct kernel_siginfo info;
1735
1736 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1737 clear_siginfo(&info);
1738 info.si_signo = SIGBUS;
1739 info.si_errno = 0;
1740 info.si_code = code;
1741 info.si_addr = addr;
1742 info.si_addr_lsb = lsb;
1743 return send_sig_info(info.si_signo, &info, t);
1744}
1745EXPORT_SYMBOL(send_sig_mceerr);
1746
1747int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1748{
1749 struct kernel_siginfo info;
1750
1751 clear_siginfo(&info);
1752 info.si_signo = SIGSEGV;
1753 info.si_errno = 0;
1754 info.si_code = SEGV_BNDERR;
1755 info.si_addr = addr;
1756 info.si_lower = lower;
1757 info.si_upper = upper;
1758 return force_sig_info(&info);
1759}
1760
1761#ifdef SEGV_PKUERR
1762int force_sig_pkuerr(void __user *addr, u32 pkey)
1763{
1764 struct kernel_siginfo info;
1765
1766 clear_siginfo(&info);
1767 info.si_signo = SIGSEGV;
1768 info.si_errno = 0;
1769 info.si_code = SEGV_PKUERR;
1770 info.si_addr = addr;
1771 info.si_pkey = pkey;
1772 return force_sig_info(&info);
1773}
1774#endif
1775
1776int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1777{
1778 struct kernel_siginfo info;
1779
1780 clear_siginfo(&info);
1781 info.si_signo = SIGTRAP;
1782 info.si_errno = 0;
1783 info.si_code = TRAP_PERF;
1784 info.si_addr = addr;
1785 info.si_perf_data = sig_data;
1786 info.si_perf_type = type;
1787
1788 /*
1789 * Signals generated by perf events should not terminate the whole
1790 * process if SIGTRAP is blocked, however, delivering the signal
1791 * asynchronously is better than not delivering at all. But tell user
1792 * space if the signal was asynchronous, so it can clearly be
1793 * distinguished from normal synchronous ones.
1794 */
1795 info.si_perf_flags = sigismember(¤t->blocked, info.si_signo) ?
1796 TRAP_PERF_FLAG_ASYNC :
1797 0;
1798
1799 return send_sig_info(info.si_signo, &info, current);
1800}
1801
1802/**
1803 * force_sig_seccomp - signals the task to allow in-process syscall emulation
1804 * @syscall: syscall number to send to userland
1805 * @reason: filter-supplied reason code to send to userland (via si_errno)
1806 * @force_coredump: true to trigger a coredump
1807 *
1808 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1809 */
1810int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1811{
1812 struct kernel_siginfo info;
1813
1814 clear_siginfo(&info);
1815 info.si_signo = SIGSYS;
1816 info.si_code = SYS_SECCOMP;
1817 info.si_call_addr = (void __user *)KSTK_EIP(current);
1818 info.si_errno = reason;
1819 info.si_arch = syscall_get_arch(current);
1820 info.si_syscall = syscall;
1821 return force_sig_info_to_task(&info, current,
1822 force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1823}
1824
1825/* For the crazy architectures that include trap information in
1826 * the errno field, instead of an actual errno value.
1827 */
1828int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1829{
1830 struct kernel_siginfo info;
1831
1832 clear_siginfo(&info);
1833 info.si_signo = SIGTRAP;
1834 info.si_errno = errno;
1835 info.si_code = TRAP_HWBKPT;
1836 info.si_addr = addr;
1837 return force_sig_info(&info);
1838}
1839
1840/* For the rare architectures that include trap information using
1841 * si_trapno.
1842 */
1843int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1844{
1845 struct kernel_siginfo info;
1846
1847 clear_siginfo(&info);
1848 info.si_signo = sig;
1849 info.si_errno = 0;
1850 info.si_code = code;
1851 info.si_addr = addr;
1852 info.si_trapno = trapno;
1853 return force_sig_info(&info);
1854}
1855
1856/* For the rare architectures that include trap information using
1857 * si_trapno.
1858 */
1859int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1860 struct task_struct *t)
1861{
1862 struct kernel_siginfo info;
1863
1864 clear_siginfo(&info);
1865 info.si_signo = sig;
1866 info.si_errno = 0;
1867 info.si_code = code;
1868 info.si_addr = addr;
1869 info.si_trapno = trapno;
1870 return send_sig_info(info.si_signo, &info, t);
1871}
1872
1873static int kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1874{
1875 int ret;
1876 read_lock(&tasklist_lock);
1877 ret = __kill_pgrp_info(sig, info, pgrp);
1878 read_unlock(&tasklist_lock);
1879 return ret;
1880}
1881
1882int kill_pgrp(struct pid *pid, int sig, int priv)
1883{
1884 return kill_pgrp_info(sig, __si_special(priv), pid);
1885}
1886EXPORT_SYMBOL(kill_pgrp);
1887
1888int kill_pid(struct pid *pid, int sig, int priv)
1889{
1890 return kill_pid_info(sig, __si_special(priv), pid);
1891}
1892EXPORT_SYMBOL(kill_pid);
1893
1894#ifdef CONFIG_POSIX_TIMERS
1895/*
1896 * These functions handle POSIX timer signals. POSIX timers use
1897 * preallocated sigqueue structs for sending signals.
1898 */
1899static void __flush_itimer_signals(struct sigpending *pending)
1900{
1901 sigset_t signal, retain;
1902 struct sigqueue *q, *n;
1903
1904 signal = pending->signal;
1905 sigemptyset(&retain);
1906
1907 list_for_each_entry_safe(q, n, &pending->list, list) {
1908 int sig = q->info.si_signo;
1909
1910 if (likely(q->info.si_code != SI_TIMER)) {
1911 sigaddset(&retain, sig);
1912 } else {
1913 sigdelset(&signal, sig);
1914 list_del_init(&q->list);
1915 __sigqueue_free(q);
1916 }
1917 }
1918
1919 sigorsets(&pending->signal, &signal, &retain);
1920}
1921
1922void flush_itimer_signals(void)
1923{
1924 struct task_struct *tsk = current;
1925
1926 guard(spinlock_irqsave)(&tsk->sighand->siglock);
1927 __flush_itimer_signals(&tsk->pending);
1928 __flush_itimer_signals(&tsk->signal->shared_pending);
1929}
1930
1931bool posixtimer_init_sigqueue(struct sigqueue *q)
1932{
1933 struct ucounts *ucounts = sig_get_ucounts(current, -1, 0);
1934
1935 if (!ucounts)
1936 return false;
1937 clear_siginfo(&q->info);
1938 __sigqueue_init(q, ucounts, SIGQUEUE_PREALLOC);
1939 return true;
1940}
1941
1942static void posixtimer_queue_sigqueue(struct sigqueue *q, struct task_struct *t, enum pid_type type)
1943{
1944 struct sigpending *pending;
1945 int sig = q->info.si_signo;
1946
1947 signalfd_notify(t, sig);
1948 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1949 list_add_tail(&q->list, &pending->list);
1950 sigaddset(&pending->signal, sig);
1951 complete_signal(sig, t, type);
1952}
1953
1954/*
1955 * This function is used by POSIX timers to deliver a timer signal.
1956 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1957 * set), the signal must be delivered to the specific thread (queues
1958 * into t->pending).
1959 *
1960 * Where type is not PIDTYPE_PID, signals must be delivered to the
1961 * process. In this case, prefer to deliver to current if it is in
1962 * the same thread group as the target process and its sighand is
1963 * stable, which avoids unnecessarily waking up a potentially idle task.
1964 */
1965static inline struct task_struct *posixtimer_get_target(struct k_itimer *tmr)
1966{
1967 struct task_struct *t = pid_task(tmr->it_pid, tmr->it_pid_type);
1968
1969 if (t && tmr->it_pid_type != PIDTYPE_PID &&
1970 same_thread_group(t, current) && !current->exit_state)
1971 t = current;
1972 return t;
1973}
1974
1975void posixtimer_send_sigqueue(struct k_itimer *tmr)
1976{
1977 struct sigqueue *q = &tmr->sigq;
1978 int sig = q->info.si_signo;
1979 struct task_struct *t;
1980 unsigned long flags;
1981 int result;
1982
1983 guard(rcu)();
1984
1985 t = posixtimer_get_target(tmr);
1986 if (!t)
1987 return;
1988
1989 if (!likely(lock_task_sighand(t, &flags)))
1990 return;
1991
1992 /*
1993 * Update @tmr::sigqueue_seq for posix timer signals with sighand
1994 * locked to prevent a race against dequeue_signal().
1995 */
1996 tmr->it_sigqueue_seq = tmr->it_signal_seq;
1997
1998 /*
1999 * Set the signal delivery status under sighand lock, so that the
2000 * ignored signal handling can distinguish between a periodic and a
2001 * non-periodic timer.
2002 */
2003 tmr->it_sig_periodic = tmr->it_status == POSIX_TIMER_REQUEUE_PENDING;
2004
2005 if (!prepare_signal(sig, t, false)) {
2006 result = TRACE_SIGNAL_IGNORED;
2007
2008 if (!list_empty(&q->list)) {
2009 /*
2010 * The signal was ignored and blocked. The timer
2011 * expiry queued it because blocked signals are
2012 * queued independent of the ignored state.
2013 *
2014 * The unblocking set SIGPENDING, but the signal
2015 * was not yet dequeued from the pending list.
2016 * So prepare_signal() sees unblocked and ignored,
2017 * which ends up here. Leave it queued like a
2018 * regular signal.
2019 *
2020 * The same happens when the task group is exiting
2021 * and the signal is already queued.
2022 * prepare_signal() treats SIGNAL_GROUP_EXIT as
2023 * ignored independent of its queued state. This
2024 * gets cleaned up in __exit_signal().
2025 */
2026 goto out;
2027 }
2028
2029 /* Periodic timers with SIG_IGN are queued on the ignored list */
2030 if (tmr->it_sig_periodic) {
2031 /*
2032 * Already queued means the timer was rearmed after
2033 * the previous expiry got it on the ignore list.
2034 * Nothing to do for that case.
2035 */
2036 if (hlist_unhashed(&tmr->ignored_list)) {
2037 /*
2038 * Take a signal reference and queue it on
2039 * the ignored list.
2040 */
2041 posixtimer_sigqueue_getref(q);
2042 posixtimer_sig_ignore(t, q);
2043 }
2044 } else if (!hlist_unhashed(&tmr->ignored_list)) {
2045 /*
2046 * Covers the case where a timer was periodic and
2047 * then the signal was ignored. Later it was rearmed
2048 * as oneshot timer. The previous signal is invalid
2049 * now, and this oneshot signal has to be dropped.
2050 * Remove it from the ignored list and drop the
2051 * reference count as the signal is not longer
2052 * queued.
2053 */
2054 hlist_del_init(&tmr->ignored_list);
2055 posixtimer_putref(tmr);
2056 }
2057 goto out;
2058 }
2059
2060 if (unlikely(!list_empty(&q->list))) {
2061 /* This holds a reference count already */
2062 result = TRACE_SIGNAL_ALREADY_PENDING;
2063 goto out;
2064 }
2065
2066 /*
2067 * If the signal is on the ignore list, it got blocked after it was
2068 * ignored earlier. But nothing lifted the ignore. Move it back to
2069 * the pending list to be consistent with the regular signal
2070 * handling. This already holds a reference count.
2071 *
2072 * If it's not on the ignore list acquire a reference count.
2073 */
2074 if (likely(hlist_unhashed(&tmr->ignored_list)))
2075 posixtimer_sigqueue_getref(q);
2076 else
2077 hlist_del_init(&tmr->ignored_list);
2078
2079 posixtimer_queue_sigqueue(q, t, tmr->it_pid_type);
2080 result = TRACE_SIGNAL_DELIVERED;
2081out:
2082 trace_signal_generate(sig, &q->info, t, tmr->it_pid_type != PIDTYPE_PID, result);
2083 unlock_task_sighand(t, &flags);
2084}
2085
2086static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q)
2087{
2088 struct k_itimer *tmr = container_of(q, struct k_itimer, sigq);
2089
2090 /*
2091 * If the timer is marked deleted already or the signal originates
2092 * from a non-periodic timer, then just drop the reference
2093 * count. Otherwise queue it on the ignored list.
2094 */
2095 if (tmr->it_signal && tmr->it_sig_periodic)
2096 hlist_add_head(&tmr->ignored_list, &tsk->signal->ignored_posix_timers);
2097 else
2098 posixtimer_putref(tmr);
2099}
2100
2101static void posixtimer_sig_unignore(struct task_struct *tsk, int sig)
2102{
2103 struct hlist_head *head = &tsk->signal->ignored_posix_timers;
2104 struct hlist_node *tmp;
2105 struct k_itimer *tmr;
2106
2107 if (likely(hlist_empty(head)))
2108 return;
2109
2110 /*
2111 * Rearming a timer with sighand lock held is not possible due to
2112 * lock ordering vs. tmr::it_lock. Just stick the sigqueue back and
2113 * let the signal delivery path deal with it whether it needs to be
2114 * rearmed or not. This cannot be decided here w/o dropping sighand
2115 * lock and creating a loop retry horror show.
2116 */
2117 hlist_for_each_entry_safe(tmr, tmp , head, ignored_list) {
2118 struct task_struct *target;
2119
2120 /*
2121 * tmr::sigq.info.si_signo is immutable, so accessing it
2122 * without holding tmr::it_lock is safe.
2123 */
2124 if (tmr->sigq.info.si_signo != sig)
2125 continue;
2126
2127 hlist_del_init(&tmr->ignored_list);
2128
2129 /* This should never happen and leaks a reference count */
2130 if (WARN_ON_ONCE(!list_empty(&tmr->sigq.list)))
2131 continue;
2132
2133 /*
2134 * Get the target for the signal. If target is a thread and
2135 * has exited by now, drop the reference count.
2136 */
2137 guard(rcu)();
2138 target = posixtimer_get_target(tmr);
2139 if (target)
2140 posixtimer_queue_sigqueue(&tmr->sigq, target, tmr->it_pid_type);
2141 else
2142 posixtimer_putref(tmr);
2143 }
2144}
2145#else /* CONFIG_POSIX_TIMERS */
2146static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q) { }
2147static inline void posixtimer_sig_unignore(struct task_struct *tsk, int sig) { }
2148#endif /* !CONFIG_POSIX_TIMERS */
2149
2150void do_notify_pidfd(struct task_struct *task)
2151{
2152 struct pid *pid = task_pid(task);
2153
2154 WARN_ON(task->exit_state == 0);
2155
2156 __wake_up(&pid->wait_pidfd, TASK_NORMAL, 0,
2157 poll_to_key(EPOLLIN | EPOLLRDNORM));
2158}
2159
2160/*
2161 * Let a parent know about the death of a child.
2162 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2163 *
2164 * Returns true if our parent ignored us and so we've switched to
2165 * self-reaping.
2166 */
2167bool do_notify_parent(struct task_struct *tsk, int sig)
2168{
2169 struct kernel_siginfo info;
2170 unsigned long flags;
2171 struct sighand_struct *psig;
2172 bool autoreap = false;
2173 u64 utime, stime;
2174
2175 WARN_ON_ONCE(sig == -1);
2176
2177 /* do_notify_parent_cldstop should have been called instead. */
2178 WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2179
2180 WARN_ON_ONCE(!tsk->ptrace &&
2181 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2182 /*
2183 * tsk is a group leader and has no threads, wake up the
2184 * non-PIDFD_THREAD waiters.
2185 */
2186 if (thread_group_empty(tsk))
2187 do_notify_pidfd(tsk);
2188
2189 if (sig != SIGCHLD) {
2190 /*
2191 * This is only possible if parent == real_parent.
2192 * Check if it has changed security domain.
2193 */
2194 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2195 sig = SIGCHLD;
2196 }
2197
2198 clear_siginfo(&info);
2199 info.si_signo = sig;
2200 info.si_errno = 0;
2201 /*
2202 * We are under tasklist_lock here so our parent is tied to
2203 * us and cannot change.
2204 *
2205 * task_active_pid_ns will always return the same pid namespace
2206 * until a task passes through release_task.
2207 *
2208 * write_lock() currently calls preempt_disable() which is the
2209 * same as rcu_read_lock(), but according to Oleg, this is not
2210 * correct to rely on this
2211 */
2212 rcu_read_lock();
2213 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2214 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2215 task_uid(tsk));
2216 rcu_read_unlock();
2217
2218 task_cputime(tsk, &utime, &stime);
2219 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2220 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2221
2222 info.si_status = tsk->exit_code & 0x7f;
2223 if (tsk->exit_code & 0x80)
2224 info.si_code = CLD_DUMPED;
2225 else if (tsk->exit_code & 0x7f)
2226 info.si_code = CLD_KILLED;
2227 else {
2228 info.si_code = CLD_EXITED;
2229 info.si_status = tsk->exit_code >> 8;
2230 }
2231
2232 psig = tsk->parent->sighand;
2233 spin_lock_irqsave(&psig->siglock, flags);
2234 if (!tsk->ptrace && sig == SIGCHLD &&
2235 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2236 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2237 /*
2238 * We are exiting and our parent doesn't care. POSIX.1
2239 * defines special semantics for setting SIGCHLD to SIG_IGN
2240 * or setting the SA_NOCLDWAIT flag: we should be reaped
2241 * automatically and not left for our parent's wait4 call.
2242 * Rather than having the parent do it as a magic kind of
2243 * signal handler, we just set this to tell do_exit that we
2244 * can be cleaned up without becoming a zombie. Note that
2245 * we still call __wake_up_parent in this case, because a
2246 * blocked sys_wait4 might now return -ECHILD.
2247 *
2248 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2249 * is implementation-defined: we do (if you don't want
2250 * it, just use SIG_IGN instead).
2251 */
2252 autoreap = true;
2253 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2254 sig = 0;
2255 }
2256 /*
2257 * Send with __send_signal as si_pid and si_uid are in the
2258 * parent's namespaces.
2259 */
2260 if (valid_signal(sig) && sig)
2261 __send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2262 __wake_up_parent(tsk, tsk->parent);
2263 spin_unlock_irqrestore(&psig->siglock, flags);
2264
2265 return autoreap;
2266}
2267
2268/**
2269 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2270 * @tsk: task reporting the state change
2271 * @for_ptracer: the notification is for ptracer
2272 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2273 *
2274 * Notify @tsk's parent that the stopped/continued state has changed. If
2275 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2276 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2277 *
2278 * CONTEXT:
2279 * Must be called with tasklist_lock at least read locked.
2280 */
2281static void do_notify_parent_cldstop(struct task_struct *tsk,
2282 bool for_ptracer, int why)
2283{
2284 struct kernel_siginfo info;
2285 unsigned long flags;
2286 struct task_struct *parent;
2287 struct sighand_struct *sighand;
2288 u64 utime, stime;
2289
2290 if (for_ptracer) {
2291 parent = tsk->parent;
2292 } else {
2293 tsk = tsk->group_leader;
2294 parent = tsk->real_parent;
2295 }
2296
2297 clear_siginfo(&info);
2298 info.si_signo = SIGCHLD;
2299 info.si_errno = 0;
2300 /*
2301 * see comment in do_notify_parent() about the following 4 lines
2302 */
2303 rcu_read_lock();
2304 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2305 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2306 rcu_read_unlock();
2307
2308 task_cputime(tsk, &utime, &stime);
2309 info.si_utime = nsec_to_clock_t(utime);
2310 info.si_stime = nsec_to_clock_t(stime);
2311
2312 info.si_code = why;
2313 switch (why) {
2314 case CLD_CONTINUED:
2315 info.si_status = SIGCONT;
2316 break;
2317 case CLD_STOPPED:
2318 info.si_status = tsk->signal->group_exit_code & 0x7f;
2319 break;
2320 case CLD_TRAPPED:
2321 info.si_status = tsk->exit_code & 0x7f;
2322 break;
2323 default:
2324 BUG();
2325 }
2326
2327 sighand = parent->sighand;
2328 spin_lock_irqsave(&sighand->siglock, flags);
2329 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2330 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2331 send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID);
2332 /*
2333 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2334 */
2335 __wake_up_parent(tsk, parent);
2336 spin_unlock_irqrestore(&sighand->siglock, flags);
2337}
2338
2339/*
2340 * This must be called with current->sighand->siglock held.
2341 *
2342 * This should be the path for all ptrace stops.
2343 * We always set current->last_siginfo while stopped here.
2344 * That makes it a way to test a stopped process for
2345 * being ptrace-stopped vs being job-control-stopped.
2346 *
2347 * Returns the signal the ptracer requested the code resume
2348 * with. If the code did not stop because the tracer is gone,
2349 * the stop signal remains unchanged unless clear_code.
2350 */
2351static int ptrace_stop(int exit_code, int why, unsigned long message,
2352 kernel_siginfo_t *info)
2353 __releases(¤t->sighand->siglock)
2354 __acquires(¤t->sighand->siglock)
2355{
2356 bool gstop_done = false;
2357
2358 if (arch_ptrace_stop_needed()) {
2359 /*
2360 * The arch code has something special to do before a
2361 * ptrace stop. This is allowed to block, e.g. for faults
2362 * on user stack pages. We can't keep the siglock while
2363 * calling arch_ptrace_stop, so we must release it now.
2364 * To preserve proper semantics, we must do this before
2365 * any signal bookkeeping like checking group_stop_count.
2366 */
2367 spin_unlock_irq(¤t->sighand->siglock);
2368 arch_ptrace_stop();
2369 spin_lock_irq(¤t->sighand->siglock);
2370 }
2371
2372 /*
2373 * After this point ptrace_signal_wake_up or signal_wake_up
2374 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
2375 * signal comes in. Handle previous ptrace_unlinks and fatal
2376 * signals here to prevent ptrace_stop sleeping in schedule.
2377 */
2378 if (!current->ptrace || __fatal_signal_pending(current))
2379 return exit_code;
2380
2381 set_special_state(TASK_TRACED);
2382 current->jobctl |= JOBCTL_TRACED;
2383
2384 /*
2385 * We're committing to trapping. TRACED should be visible before
2386 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2387 * Also, transition to TRACED and updates to ->jobctl should be
2388 * atomic with respect to siglock and should be done after the arch
2389 * hook as siglock is released and regrabbed across it.
2390 *
2391 * TRACER TRACEE
2392 *
2393 * ptrace_attach()
2394 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2395 * do_wait()
2396 * set_current_state() smp_wmb();
2397 * ptrace_do_wait()
2398 * wait_task_stopped()
2399 * task_stopped_code()
2400 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2401 */
2402 smp_wmb();
2403
2404 current->ptrace_message = message;
2405 current->last_siginfo = info;
2406 current->exit_code = exit_code;
2407
2408 /*
2409 * If @why is CLD_STOPPED, we're trapping to participate in a group
2410 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2411 * across siglock relocks since INTERRUPT was scheduled, PENDING
2412 * could be clear now. We act as if SIGCONT is received after
2413 * TASK_TRACED is entered - ignore it.
2414 */
2415 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2416 gstop_done = task_participate_group_stop(current);
2417
2418 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2419 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2420 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2421 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2422
2423 /* entering a trap, clear TRAPPING */
2424 task_clear_jobctl_trapping(current);
2425
2426 spin_unlock_irq(¤t->sighand->siglock);
2427 read_lock(&tasklist_lock);
2428 /*
2429 * Notify parents of the stop.
2430 *
2431 * While ptraced, there are two parents - the ptracer and
2432 * the real_parent of the group_leader. The ptracer should
2433 * know about every stop while the real parent is only
2434 * interested in the completion of group stop. The states
2435 * for the two don't interact with each other. Notify
2436 * separately unless they're gonna be duplicates.
2437 */
2438 if (current->ptrace)
2439 do_notify_parent_cldstop(current, true, why);
2440 if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2441 do_notify_parent_cldstop(current, false, why);
2442
2443 /*
2444 * The previous do_notify_parent_cldstop() invocation woke ptracer.
2445 * One a PREEMPTION kernel this can result in preemption requirement
2446 * which will be fulfilled after read_unlock() and the ptracer will be
2447 * put on the CPU.
2448 * The ptracer is in wait_task_inactive(, __TASK_TRACED) waiting for
2449 * this task wait in schedule(). If this task gets preempted then it
2450 * remains enqueued on the runqueue. The ptracer will observe this and
2451 * then sleep for a delay of one HZ tick. In the meantime this task
2452 * gets scheduled, enters schedule() and will wait for the ptracer.
2453 *
2454 * This preemption point is not bad from a correctness point of
2455 * view but extends the runtime by one HZ tick time due to the
2456 * ptracer's sleep. The preempt-disable section ensures that there
2457 * will be no preemption between unlock and schedule() and so
2458 * improving the performance since the ptracer will observe that
2459 * the tracee is scheduled out once it gets on the CPU.
2460 *
2461 * On PREEMPT_RT locking tasklist_lock does not disable preemption.
2462 * Therefore the task can be preempted after do_notify_parent_cldstop()
2463 * before unlocking tasklist_lock so there is no benefit in doing this.
2464 *
2465 * In fact disabling preemption is harmful on PREEMPT_RT because
2466 * the spinlock_t in cgroup_enter_frozen() must not be acquired
2467 * with preemption disabled due to the 'sleeping' spinlock
2468 * substitution of RT.
2469 */
2470 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2471 preempt_disable();
2472 read_unlock(&tasklist_lock);
2473 cgroup_enter_frozen();
2474 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2475 preempt_enable_no_resched();
2476 schedule();
2477 cgroup_leave_frozen(true);
2478
2479 /*
2480 * We are back. Now reacquire the siglock before touching
2481 * last_siginfo, so that we are sure to have synchronized with
2482 * any signal-sending on another CPU that wants to examine it.
2483 */
2484 spin_lock_irq(¤t->sighand->siglock);
2485 exit_code = current->exit_code;
2486 current->last_siginfo = NULL;
2487 current->ptrace_message = 0;
2488 current->exit_code = 0;
2489
2490 /* LISTENING can be set only during STOP traps, clear it */
2491 current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2492
2493 /*
2494 * Queued signals ignored us while we were stopped for tracing.
2495 * So check for any that we should take before resuming user mode.
2496 * This sets TIF_SIGPENDING, but never clears it.
2497 */
2498 recalc_sigpending_tsk(current);
2499 return exit_code;
2500}
2501
2502static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2503{
2504 kernel_siginfo_t info;
2505
2506 clear_siginfo(&info);
2507 info.si_signo = signr;
2508 info.si_code = exit_code;
2509 info.si_pid = task_pid_vnr(current);
2510 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2511
2512 /* Let the debugger run. */
2513 return ptrace_stop(exit_code, why, message, &info);
2514}
2515
2516int ptrace_notify(int exit_code, unsigned long message)
2517{
2518 int signr;
2519
2520 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2521 if (unlikely(task_work_pending(current)))
2522 task_work_run();
2523
2524 spin_lock_irq(¤t->sighand->siglock);
2525 signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2526 spin_unlock_irq(¤t->sighand->siglock);
2527 return signr;
2528}
2529
2530/**
2531 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2532 * @signr: signr causing group stop if initiating
2533 *
2534 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2535 * and participate in it. If already set, participate in the existing
2536 * group stop. If participated in a group stop (and thus slept), %true is
2537 * returned with siglock released.
2538 *
2539 * If ptraced, this function doesn't handle stop itself. Instead,
2540 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2541 * untouched. The caller must ensure that INTERRUPT trap handling takes
2542 * places afterwards.
2543 *
2544 * CONTEXT:
2545 * Must be called with @current->sighand->siglock held, which is released
2546 * on %true return.
2547 *
2548 * RETURNS:
2549 * %false if group stop is already cancelled or ptrace trap is scheduled.
2550 * %true if participated in group stop.
2551 */
2552static bool do_signal_stop(int signr)
2553 __releases(¤t->sighand->siglock)
2554{
2555 struct signal_struct *sig = current->signal;
2556
2557 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2558 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2559 struct task_struct *t;
2560
2561 /* signr will be recorded in task->jobctl for retries */
2562 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2563
2564 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2565 unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2566 unlikely(sig->group_exec_task))
2567 return false;
2568 /*
2569 * There is no group stop already in progress. We must
2570 * initiate one now.
2571 *
2572 * While ptraced, a task may be resumed while group stop is
2573 * still in effect and then receive a stop signal and
2574 * initiate another group stop. This deviates from the
2575 * usual behavior as two consecutive stop signals can't
2576 * cause two group stops when !ptraced. That is why we
2577 * also check !task_is_stopped(t) below.
2578 *
2579 * The condition can be distinguished by testing whether
2580 * SIGNAL_STOP_STOPPED is already set. Don't generate
2581 * group_exit_code in such case.
2582 *
2583 * This is not necessary for SIGNAL_STOP_CONTINUED because
2584 * an intervening stop signal is required to cause two
2585 * continued events regardless of ptrace.
2586 */
2587 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2588 sig->group_exit_code = signr;
2589
2590 sig->group_stop_count = 0;
2591 if (task_set_jobctl_pending(current, signr | gstop))
2592 sig->group_stop_count++;
2593
2594 for_other_threads(current, t) {
2595 /*
2596 * Setting state to TASK_STOPPED for a group
2597 * stop is always done with the siglock held,
2598 * so this check has no races.
2599 */
2600 if (!task_is_stopped(t) &&
2601 task_set_jobctl_pending(t, signr | gstop)) {
2602 sig->group_stop_count++;
2603 if (likely(!(t->ptrace & PT_SEIZED)))
2604 signal_wake_up(t, 0);
2605 else
2606 ptrace_trap_notify(t);
2607 }
2608 }
2609 }
2610
2611 if (likely(!current->ptrace)) {
2612 int notify = 0;
2613
2614 /*
2615 * If there are no other threads in the group, or if there
2616 * is a group stop in progress and we are the last to stop,
2617 * report to the parent.
2618 */
2619 if (task_participate_group_stop(current))
2620 notify = CLD_STOPPED;
2621
2622 current->jobctl |= JOBCTL_STOPPED;
2623 set_special_state(TASK_STOPPED);
2624 spin_unlock_irq(¤t->sighand->siglock);
2625
2626 /*
2627 * Notify the parent of the group stop completion. Because
2628 * we're not holding either the siglock or tasklist_lock
2629 * here, ptracer may attach inbetween; however, this is for
2630 * group stop and should always be delivered to the real
2631 * parent of the group leader. The new ptracer will get
2632 * its notification when this task transitions into
2633 * TASK_TRACED.
2634 */
2635 if (notify) {
2636 read_lock(&tasklist_lock);
2637 do_notify_parent_cldstop(current, false, notify);
2638 read_unlock(&tasklist_lock);
2639 }
2640
2641 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2642 cgroup_enter_frozen();
2643 schedule();
2644 return true;
2645 } else {
2646 /*
2647 * While ptraced, group stop is handled by STOP trap.
2648 * Schedule it and let the caller deal with it.
2649 */
2650 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2651 return false;
2652 }
2653}
2654
2655/**
2656 * do_jobctl_trap - take care of ptrace jobctl traps
2657 *
2658 * When PT_SEIZED, it's used for both group stop and explicit
2659 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2660 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2661 * the stop signal; otherwise, %SIGTRAP.
2662 *
2663 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2664 * number as exit_code and no siginfo.
2665 *
2666 * CONTEXT:
2667 * Must be called with @current->sighand->siglock held, which may be
2668 * released and re-acquired before returning with intervening sleep.
2669 */
2670static void do_jobctl_trap(void)
2671{
2672 struct signal_struct *signal = current->signal;
2673 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2674
2675 if (current->ptrace & PT_SEIZED) {
2676 if (!signal->group_stop_count &&
2677 !(signal->flags & SIGNAL_STOP_STOPPED))
2678 signr = SIGTRAP;
2679 WARN_ON_ONCE(!signr);
2680 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2681 CLD_STOPPED, 0);
2682 } else {
2683 WARN_ON_ONCE(!signr);
2684 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2685 }
2686}
2687
2688/**
2689 * do_freezer_trap - handle the freezer jobctl trap
2690 *
2691 * Puts the task into frozen state, if only the task is not about to quit.
2692 * In this case it drops JOBCTL_TRAP_FREEZE.
2693 *
2694 * CONTEXT:
2695 * Must be called with @current->sighand->siglock held,
2696 * which is always released before returning.
2697 */
2698static void do_freezer_trap(void)
2699 __releases(¤t->sighand->siglock)
2700{
2701 /*
2702 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2703 * let's make another loop to give it a chance to be handled.
2704 * In any case, we'll return back.
2705 */
2706 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2707 JOBCTL_TRAP_FREEZE) {
2708 spin_unlock_irq(¤t->sighand->siglock);
2709 return;
2710 }
2711
2712 /*
2713 * Now we're sure that there is no pending fatal signal and no
2714 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2715 * immediately (if there is a non-fatal signal pending), and
2716 * put the task into sleep.
2717 */
2718 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2719 clear_thread_flag(TIF_SIGPENDING);
2720 spin_unlock_irq(¤t->sighand->siglock);
2721 cgroup_enter_frozen();
2722 schedule();
2723
2724 /*
2725 * We could've been woken by task_work, run it to clear
2726 * TIF_NOTIFY_SIGNAL. The caller will retry if necessary.
2727 */
2728 clear_notify_signal();
2729 if (unlikely(task_work_pending(current)))
2730 task_work_run();
2731}
2732
2733static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2734{
2735 /*
2736 * We do not check sig_kernel_stop(signr) but set this marker
2737 * unconditionally because we do not know whether debugger will
2738 * change signr. This flag has no meaning unless we are going
2739 * to stop after return from ptrace_stop(). In this case it will
2740 * be checked in do_signal_stop(), we should only stop if it was
2741 * not cleared by SIGCONT while we were sleeping. See also the
2742 * comment in dequeue_signal().
2743 */
2744 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2745 signr = ptrace_stop(signr, CLD_TRAPPED, 0, info);
2746
2747 /* We're back. Did the debugger cancel the sig? */
2748 if (signr == 0)
2749 return signr;
2750
2751 /*
2752 * Update the siginfo structure if the signal has
2753 * changed. If the debugger wanted something
2754 * specific in the siginfo structure then it should
2755 * have updated *info via PTRACE_SETSIGINFO.
2756 */
2757 if (signr != info->si_signo) {
2758 clear_siginfo(info);
2759 info->si_signo = signr;
2760 info->si_errno = 0;
2761 info->si_code = SI_USER;
2762 rcu_read_lock();
2763 info->si_pid = task_pid_vnr(current->parent);
2764 info->si_uid = from_kuid_munged(current_user_ns(),
2765 task_uid(current->parent));
2766 rcu_read_unlock();
2767 }
2768
2769 /* If the (new) signal is now blocked, requeue it. */
2770 if (sigismember(¤t->blocked, signr) ||
2771 fatal_signal_pending(current)) {
2772 send_signal_locked(signr, info, current, type);
2773 signr = 0;
2774 }
2775
2776 return signr;
2777}
2778
2779static void hide_si_addr_tag_bits(struct ksignal *ksig)
2780{
2781 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2782 case SIL_FAULT:
2783 case SIL_FAULT_TRAPNO:
2784 case SIL_FAULT_MCEERR:
2785 case SIL_FAULT_BNDERR:
2786 case SIL_FAULT_PKUERR:
2787 case SIL_FAULT_PERF_EVENT:
2788 ksig->info.si_addr = arch_untagged_si_addr(
2789 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2790 break;
2791 case SIL_KILL:
2792 case SIL_TIMER:
2793 case SIL_POLL:
2794 case SIL_CHLD:
2795 case SIL_RT:
2796 case SIL_SYS:
2797 break;
2798 }
2799}
2800
2801bool get_signal(struct ksignal *ksig)
2802{
2803 struct sighand_struct *sighand = current->sighand;
2804 struct signal_struct *signal = current->signal;
2805 int signr;
2806
2807 clear_notify_signal();
2808 if (unlikely(task_work_pending(current)))
2809 task_work_run();
2810
2811 if (!task_sigpending(current))
2812 return false;
2813
2814 if (unlikely(uprobe_deny_signal()))
2815 return false;
2816
2817 /*
2818 * Do this once, we can't return to user-mode if freezing() == T.
2819 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2820 * thus do not need another check after return.
2821 */
2822 try_to_freeze();
2823
2824relock:
2825 spin_lock_irq(&sighand->siglock);
2826
2827 /*
2828 * Every stopped thread goes here after wakeup. Check to see if
2829 * we should notify the parent, prepare_signal(SIGCONT) encodes
2830 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2831 */
2832 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2833 int why;
2834
2835 if (signal->flags & SIGNAL_CLD_CONTINUED)
2836 why = CLD_CONTINUED;
2837 else
2838 why = CLD_STOPPED;
2839
2840 signal->flags &= ~SIGNAL_CLD_MASK;
2841
2842 spin_unlock_irq(&sighand->siglock);
2843
2844 /*
2845 * Notify the parent that we're continuing. This event is
2846 * always per-process and doesn't make whole lot of sense
2847 * for ptracers, who shouldn't consume the state via
2848 * wait(2) either, but, for backward compatibility, notify
2849 * the ptracer of the group leader too unless it's gonna be
2850 * a duplicate.
2851 */
2852 read_lock(&tasklist_lock);
2853 do_notify_parent_cldstop(current, false, why);
2854
2855 if (ptrace_reparented(current->group_leader))
2856 do_notify_parent_cldstop(current->group_leader,
2857 true, why);
2858 read_unlock(&tasklist_lock);
2859
2860 goto relock;
2861 }
2862
2863 for (;;) {
2864 struct k_sigaction *ka;
2865 enum pid_type type;
2866
2867 /* Has this task already been marked for death? */
2868 if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2869 signal->group_exec_task) {
2870 signr = SIGKILL;
2871 sigdelset(¤t->pending.signal, SIGKILL);
2872 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2873 &sighand->action[SIGKILL-1]);
2874 recalc_sigpending();
2875 /*
2876 * implies do_group_exit() or return to PF_USER_WORKER,
2877 * no need to initialize ksig->info/etc.
2878 */
2879 goto fatal;
2880 }
2881
2882 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2883 do_signal_stop(0))
2884 goto relock;
2885
2886 if (unlikely(current->jobctl &
2887 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2888 if (current->jobctl & JOBCTL_TRAP_MASK) {
2889 do_jobctl_trap();
2890 spin_unlock_irq(&sighand->siglock);
2891 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2892 do_freezer_trap();
2893
2894 goto relock;
2895 }
2896
2897 /*
2898 * If the task is leaving the frozen state, let's update
2899 * cgroup counters and reset the frozen bit.
2900 */
2901 if (unlikely(cgroup_task_frozen(current))) {
2902 spin_unlock_irq(&sighand->siglock);
2903 cgroup_leave_frozen(false);
2904 goto relock;
2905 }
2906
2907 /*
2908 * Signals generated by the execution of an instruction
2909 * need to be delivered before any other pending signals
2910 * so that the instruction pointer in the signal stack
2911 * frame points to the faulting instruction.
2912 */
2913 type = PIDTYPE_PID;
2914 signr = dequeue_synchronous_signal(&ksig->info);
2915 if (!signr)
2916 signr = dequeue_signal(¤t->blocked, &ksig->info, &type);
2917
2918 if (!signr)
2919 break; /* will return 0 */
2920
2921 if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2922 !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2923 signr = ptrace_signal(signr, &ksig->info, type);
2924 if (!signr)
2925 continue;
2926 }
2927
2928 ka = &sighand->action[signr-1];
2929
2930 /* Trace actually delivered signals. */
2931 trace_signal_deliver(signr, &ksig->info, ka);
2932
2933 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2934 continue;
2935 if (ka->sa.sa_handler != SIG_DFL) {
2936 /* Run the handler. */
2937 ksig->ka = *ka;
2938
2939 if (ka->sa.sa_flags & SA_ONESHOT)
2940 ka->sa.sa_handler = SIG_DFL;
2941
2942 break; /* will return non-zero "signr" value */
2943 }
2944
2945 /*
2946 * Now we are doing the default action for this signal.
2947 */
2948 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2949 continue;
2950
2951 /*
2952 * Global init gets no signals it doesn't want.
2953 * Container-init gets no signals it doesn't want from same
2954 * container.
2955 *
2956 * Note that if global/container-init sees a sig_kernel_only()
2957 * signal here, the signal must have been generated internally
2958 * or must have come from an ancestor namespace. In either
2959 * case, the signal cannot be dropped.
2960 */
2961 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2962 !sig_kernel_only(signr))
2963 continue;
2964
2965 if (sig_kernel_stop(signr)) {
2966 /*
2967 * The default action is to stop all threads in
2968 * the thread group. The job control signals
2969 * do nothing in an orphaned pgrp, but SIGSTOP
2970 * always works. Note that siglock needs to be
2971 * dropped during the call to is_orphaned_pgrp()
2972 * because of lock ordering with tasklist_lock.
2973 * This allows an intervening SIGCONT to be posted.
2974 * We need to check for that and bail out if necessary.
2975 */
2976 if (signr != SIGSTOP) {
2977 spin_unlock_irq(&sighand->siglock);
2978
2979 /* signals can be posted during this window */
2980
2981 if (is_current_pgrp_orphaned())
2982 goto relock;
2983
2984 spin_lock_irq(&sighand->siglock);
2985 }
2986
2987 if (likely(do_signal_stop(signr))) {
2988 /* It released the siglock. */
2989 goto relock;
2990 }
2991
2992 /*
2993 * We didn't actually stop, due to a race
2994 * with SIGCONT or something like that.
2995 */
2996 continue;
2997 }
2998
2999 fatal:
3000 spin_unlock_irq(&sighand->siglock);
3001 if (unlikely(cgroup_task_frozen(current)))
3002 cgroup_leave_frozen(true);
3003
3004 /*
3005 * Anything else is fatal, maybe with a core dump.
3006 */
3007 current->flags |= PF_SIGNALED;
3008
3009 if (sig_kernel_coredump(signr)) {
3010 if (print_fatal_signals)
3011 print_fatal_signal(signr);
3012 proc_coredump_connector(current);
3013 /*
3014 * If it was able to dump core, this kills all
3015 * other threads in the group and synchronizes with
3016 * their demise. If we lost the race with another
3017 * thread getting here, it set group_exit_code
3018 * first and our do_group_exit call below will use
3019 * that value and ignore the one we pass it.
3020 */
3021 do_coredump(&ksig->info);
3022 }
3023
3024 /*
3025 * PF_USER_WORKER threads will catch and exit on fatal signals
3026 * themselves. They have cleanup that must be performed, so we
3027 * cannot call do_exit() on their behalf. Note that ksig won't
3028 * be properly initialized, PF_USER_WORKER's shouldn't use it.
3029 */
3030 if (current->flags & PF_USER_WORKER)
3031 goto out;
3032
3033 /*
3034 * Death signals, no core dump.
3035 */
3036 do_group_exit(signr);
3037 /* NOTREACHED */
3038 }
3039 spin_unlock_irq(&sighand->siglock);
3040
3041 ksig->sig = signr;
3042
3043 if (signr && !(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
3044 hide_si_addr_tag_bits(ksig);
3045out:
3046 return signr > 0;
3047}
3048
3049/**
3050 * signal_delivered - called after signal delivery to update blocked signals
3051 * @ksig: kernel signal struct
3052 * @stepping: nonzero if debugger single-step or block-step in use
3053 *
3054 * This function should be called when a signal has successfully been
3055 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
3056 * is always blocked), and the signal itself is blocked unless %SA_NODEFER
3057 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
3058 */
3059static void signal_delivered(struct ksignal *ksig, int stepping)
3060{
3061 sigset_t blocked;
3062
3063 /* A signal was successfully delivered, and the
3064 saved sigmask was stored on the signal frame,
3065 and will be restored by sigreturn. So we can
3066 simply clear the restore sigmask flag. */
3067 clear_restore_sigmask();
3068
3069 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
3070 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
3071 sigaddset(&blocked, ksig->sig);
3072 set_current_blocked(&blocked);
3073 if (current->sas_ss_flags & SS_AUTODISARM)
3074 sas_ss_reset(current);
3075 if (stepping)
3076 ptrace_notify(SIGTRAP, 0);
3077}
3078
3079void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
3080{
3081 if (failed)
3082 force_sigsegv(ksig->sig);
3083 else
3084 signal_delivered(ksig, stepping);
3085}
3086
3087/*
3088 * It could be that complete_signal() picked us to notify about the
3089 * group-wide signal. Other threads should be notified now to take
3090 * the shared signals in @which since we will not.
3091 */
3092static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
3093{
3094 sigset_t retarget;
3095 struct task_struct *t;
3096
3097 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
3098 if (sigisemptyset(&retarget))
3099 return;
3100
3101 for_other_threads(tsk, t) {
3102 if (t->flags & PF_EXITING)
3103 continue;
3104
3105 if (!has_pending_signals(&retarget, &t->blocked))
3106 continue;
3107 /* Remove the signals this thread can handle. */
3108 sigandsets(&retarget, &retarget, &t->blocked);
3109
3110 if (!task_sigpending(t))
3111 signal_wake_up(t, 0);
3112
3113 if (sigisemptyset(&retarget))
3114 break;
3115 }
3116}
3117
3118void exit_signals(struct task_struct *tsk)
3119{
3120 int group_stop = 0;
3121 sigset_t unblocked;
3122
3123 /*
3124 * @tsk is about to have PF_EXITING set - lock out users which
3125 * expect stable threadgroup.
3126 */
3127 cgroup_threadgroup_change_begin(tsk);
3128
3129 if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
3130 sched_mm_cid_exit_signals(tsk);
3131 tsk->flags |= PF_EXITING;
3132 cgroup_threadgroup_change_end(tsk);
3133 return;
3134 }
3135
3136 spin_lock_irq(&tsk->sighand->siglock);
3137 /*
3138 * From now this task is not visible for group-wide signals,
3139 * see wants_signal(), do_signal_stop().
3140 */
3141 sched_mm_cid_exit_signals(tsk);
3142 tsk->flags |= PF_EXITING;
3143
3144 cgroup_threadgroup_change_end(tsk);
3145
3146 if (!task_sigpending(tsk))
3147 goto out;
3148
3149 unblocked = tsk->blocked;
3150 signotset(&unblocked);
3151 retarget_shared_pending(tsk, &unblocked);
3152
3153 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3154 task_participate_group_stop(tsk))
3155 group_stop = CLD_STOPPED;
3156out:
3157 spin_unlock_irq(&tsk->sighand->siglock);
3158
3159 /*
3160 * If group stop has completed, deliver the notification. This
3161 * should always go to the real parent of the group leader.
3162 */
3163 if (unlikely(group_stop)) {
3164 read_lock(&tasklist_lock);
3165 do_notify_parent_cldstop(tsk, false, group_stop);
3166 read_unlock(&tasklist_lock);
3167 }
3168}
3169
3170/*
3171 * System call entry points.
3172 */
3173
3174/**
3175 * sys_restart_syscall - restart a system call
3176 */
3177SYSCALL_DEFINE0(restart_syscall)
3178{
3179 struct restart_block *restart = ¤t->restart_block;
3180 return restart->fn(restart);
3181}
3182
3183long do_no_restart_syscall(struct restart_block *param)
3184{
3185 return -EINTR;
3186}
3187
3188static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3189{
3190 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
3191 sigset_t newblocked;
3192 /* A set of now blocked but previously unblocked signals. */
3193 sigandnsets(&newblocked, newset, ¤t->blocked);
3194 retarget_shared_pending(tsk, &newblocked);
3195 }
3196 tsk->blocked = *newset;
3197 recalc_sigpending();
3198}
3199
3200/**
3201 * set_current_blocked - change current->blocked mask
3202 * @newset: new mask
3203 *
3204 * It is wrong to change ->blocked directly, this helper should be used
3205 * to ensure the process can't miss a shared signal we are going to block.
3206 */
3207void set_current_blocked(sigset_t *newset)
3208{
3209 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3210 __set_current_blocked(newset);
3211}
3212
3213void __set_current_blocked(const sigset_t *newset)
3214{
3215 struct task_struct *tsk = current;
3216
3217 /*
3218 * In case the signal mask hasn't changed, there is nothing we need
3219 * to do. The current->blocked shouldn't be modified by other task.
3220 */
3221 if (sigequalsets(&tsk->blocked, newset))
3222 return;
3223
3224 spin_lock_irq(&tsk->sighand->siglock);
3225 __set_task_blocked(tsk, newset);
3226 spin_unlock_irq(&tsk->sighand->siglock);
3227}
3228
3229/*
3230 * This is also useful for kernel threads that want to temporarily
3231 * (or permanently) block certain signals.
3232 *
3233 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3234 * interface happily blocks "unblockable" signals like SIGKILL
3235 * and friends.
3236 */
3237int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3238{
3239 struct task_struct *tsk = current;
3240 sigset_t newset;
3241
3242 /* Lockless, only current can change ->blocked, never from irq */
3243 if (oldset)
3244 *oldset = tsk->blocked;
3245
3246 switch (how) {
3247 case SIG_BLOCK:
3248 sigorsets(&newset, &tsk->blocked, set);
3249 break;
3250 case SIG_UNBLOCK:
3251 sigandnsets(&newset, &tsk->blocked, set);
3252 break;
3253 case SIG_SETMASK:
3254 newset = *set;
3255 break;
3256 default:
3257 return -EINVAL;
3258 }
3259
3260 __set_current_blocked(&newset);
3261 return 0;
3262}
3263EXPORT_SYMBOL(sigprocmask);
3264
3265/*
3266 * The api helps set app-provided sigmasks.
3267 *
3268 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3269 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3270 *
3271 * Note that it does set_restore_sigmask() in advance, so it must be always
3272 * paired with restore_saved_sigmask_unless() before return from syscall.
3273 */
3274int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3275{
3276 sigset_t kmask;
3277
3278 if (!umask)
3279 return 0;
3280 if (sigsetsize != sizeof(sigset_t))
3281 return -EINVAL;
3282 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3283 return -EFAULT;
3284
3285 set_restore_sigmask();
3286 current->saved_sigmask = current->blocked;
3287 set_current_blocked(&kmask);
3288
3289 return 0;
3290}
3291
3292#ifdef CONFIG_COMPAT
3293int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3294 size_t sigsetsize)
3295{
3296 sigset_t kmask;
3297
3298 if (!umask)
3299 return 0;
3300 if (sigsetsize != sizeof(compat_sigset_t))
3301 return -EINVAL;
3302 if (get_compat_sigset(&kmask, umask))
3303 return -EFAULT;
3304
3305 set_restore_sigmask();
3306 current->saved_sigmask = current->blocked;
3307 set_current_blocked(&kmask);
3308
3309 return 0;
3310}
3311#endif
3312
3313/**
3314 * sys_rt_sigprocmask - change the list of currently blocked signals
3315 * @how: whether to add, remove, or set signals
3316 * @nset: stores pending signals
3317 * @oset: previous value of signal mask if non-null
3318 * @sigsetsize: size of sigset_t type
3319 */
3320SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3321 sigset_t __user *, oset, size_t, sigsetsize)
3322{
3323 sigset_t old_set, new_set;
3324 int error;
3325
3326 /* XXX: Don't preclude handling different sized sigset_t's. */
3327 if (sigsetsize != sizeof(sigset_t))
3328 return -EINVAL;
3329
3330 old_set = current->blocked;
3331
3332 if (nset) {
3333 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3334 return -EFAULT;
3335 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3336
3337 error = sigprocmask(how, &new_set, NULL);
3338 if (error)
3339 return error;
3340 }
3341
3342 if (oset) {
3343 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3344 return -EFAULT;
3345 }
3346
3347 return 0;
3348}
3349
3350#ifdef CONFIG_COMPAT
3351COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3352 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3353{
3354 sigset_t old_set = current->blocked;
3355
3356 /* XXX: Don't preclude handling different sized sigset_t's. */
3357 if (sigsetsize != sizeof(sigset_t))
3358 return -EINVAL;
3359
3360 if (nset) {
3361 sigset_t new_set;
3362 int error;
3363 if (get_compat_sigset(&new_set, nset))
3364 return -EFAULT;
3365 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3366
3367 error = sigprocmask(how, &new_set, NULL);
3368 if (error)
3369 return error;
3370 }
3371 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3372}
3373#endif
3374
3375static void do_sigpending(sigset_t *set)
3376{
3377 spin_lock_irq(¤t->sighand->siglock);
3378 sigorsets(set, ¤t->pending.signal,
3379 ¤t->signal->shared_pending.signal);
3380 spin_unlock_irq(¤t->sighand->siglock);
3381
3382 /* Outside the lock because only this thread touches it. */
3383 sigandsets(set, ¤t->blocked, set);
3384}
3385
3386/**
3387 * sys_rt_sigpending - examine a pending signal that has been raised
3388 * while blocked
3389 * @uset: stores pending signals
3390 * @sigsetsize: size of sigset_t type or larger
3391 */
3392SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3393{
3394 sigset_t set;
3395
3396 if (sigsetsize > sizeof(*uset))
3397 return -EINVAL;
3398
3399 do_sigpending(&set);
3400
3401 if (copy_to_user(uset, &set, sigsetsize))
3402 return -EFAULT;
3403
3404 return 0;
3405}
3406
3407#ifdef CONFIG_COMPAT
3408COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3409 compat_size_t, sigsetsize)
3410{
3411 sigset_t set;
3412
3413 if (sigsetsize > sizeof(*uset))
3414 return -EINVAL;
3415
3416 do_sigpending(&set);
3417
3418 return put_compat_sigset(uset, &set, sigsetsize);
3419}
3420#endif
3421
3422static const struct {
3423 unsigned char limit, layout;
3424} sig_sicodes[] = {
3425 [SIGILL] = { NSIGILL, SIL_FAULT },
3426 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3427 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3428 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3429 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3430#if defined(SIGEMT)
3431 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3432#endif
3433 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3434 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3435 [SIGSYS] = { NSIGSYS, SIL_SYS },
3436};
3437
3438static bool known_siginfo_layout(unsigned sig, int si_code)
3439{
3440 if (si_code == SI_KERNEL)
3441 return true;
3442 else if ((si_code > SI_USER)) {
3443 if (sig_specific_sicodes(sig)) {
3444 if (si_code <= sig_sicodes[sig].limit)
3445 return true;
3446 }
3447 else if (si_code <= NSIGPOLL)
3448 return true;
3449 }
3450 else if (si_code >= SI_DETHREAD)
3451 return true;
3452 else if (si_code == SI_ASYNCNL)
3453 return true;
3454 return false;
3455}
3456
3457enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3458{
3459 enum siginfo_layout layout = SIL_KILL;
3460 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3461 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3462 (si_code <= sig_sicodes[sig].limit)) {
3463 layout = sig_sicodes[sig].layout;
3464 /* Handle the exceptions */
3465 if ((sig == SIGBUS) &&
3466 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3467 layout = SIL_FAULT_MCEERR;
3468 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3469 layout = SIL_FAULT_BNDERR;
3470#ifdef SEGV_PKUERR
3471 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3472 layout = SIL_FAULT_PKUERR;
3473#endif
3474 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3475 layout = SIL_FAULT_PERF_EVENT;
3476 else if (IS_ENABLED(CONFIG_SPARC) &&
3477 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3478 layout = SIL_FAULT_TRAPNO;
3479 else if (IS_ENABLED(CONFIG_ALPHA) &&
3480 ((sig == SIGFPE) ||
3481 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3482 layout = SIL_FAULT_TRAPNO;
3483 }
3484 else if (si_code <= NSIGPOLL)
3485 layout = SIL_POLL;
3486 } else {
3487 if (si_code == SI_TIMER)
3488 layout = SIL_TIMER;
3489 else if (si_code == SI_SIGIO)
3490 layout = SIL_POLL;
3491 else if (si_code < 0)
3492 layout = SIL_RT;
3493 }
3494 return layout;
3495}
3496
3497static inline char __user *si_expansion(const siginfo_t __user *info)
3498{
3499 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3500}
3501
3502int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3503{
3504 char __user *expansion = si_expansion(to);
3505 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3506 return -EFAULT;
3507 if (clear_user(expansion, SI_EXPANSION_SIZE))
3508 return -EFAULT;
3509 return 0;
3510}
3511
3512static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3513 const siginfo_t __user *from)
3514{
3515 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3516 char __user *expansion = si_expansion(from);
3517 char buf[SI_EXPANSION_SIZE];
3518 int i;
3519 /*
3520 * An unknown si_code might need more than
3521 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3522 * extra bytes are 0. This guarantees copy_siginfo_to_user
3523 * will return this data to userspace exactly.
3524 */
3525 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3526 return -EFAULT;
3527 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3528 if (buf[i] != 0)
3529 return -E2BIG;
3530 }
3531 }
3532 return 0;
3533}
3534
3535static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3536 const siginfo_t __user *from)
3537{
3538 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3539 return -EFAULT;
3540 to->si_signo = signo;
3541 return post_copy_siginfo_from_user(to, from);
3542}
3543
3544int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3545{
3546 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3547 return -EFAULT;
3548 return post_copy_siginfo_from_user(to, from);
3549}
3550
3551#ifdef CONFIG_COMPAT
3552/**
3553 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3554 * @to: compat siginfo destination
3555 * @from: kernel siginfo source
3556 *
3557 * Note: This function does not work properly for the SIGCHLD on x32, but
3558 * fortunately it doesn't have to. The only valid callers for this function are
3559 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3560 * The latter does not care because SIGCHLD will never cause a coredump.
3561 */
3562void copy_siginfo_to_external32(struct compat_siginfo *to,
3563 const struct kernel_siginfo *from)
3564{
3565 memset(to, 0, sizeof(*to));
3566
3567 to->si_signo = from->si_signo;
3568 to->si_errno = from->si_errno;
3569 to->si_code = from->si_code;
3570 switch(siginfo_layout(from->si_signo, from->si_code)) {
3571 case SIL_KILL:
3572 to->si_pid = from->si_pid;
3573 to->si_uid = from->si_uid;
3574 break;
3575 case SIL_TIMER:
3576 to->si_tid = from->si_tid;
3577 to->si_overrun = from->si_overrun;
3578 to->si_int = from->si_int;
3579 break;
3580 case SIL_POLL:
3581 to->si_band = from->si_band;
3582 to->si_fd = from->si_fd;
3583 break;
3584 case SIL_FAULT:
3585 to->si_addr = ptr_to_compat(from->si_addr);
3586 break;
3587 case SIL_FAULT_TRAPNO:
3588 to->si_addr = ptr_to_compat(from->si_addr);
3589 to->si_trapno = from->si_trapno;
3590 break;
3591 case SIL_FAULT_MCEERR:
3592 to->si_addr = ptr_to_compat(from->si_addr);
3593 to->si_addr_lsb = from->si_addr_lsb;
3594 break;
3595 case SIL_FAULT_BNDERR:
3596 to->si_addr = ptr_to_compat(from->si_addr);
3597 to->si_lower = ptr_to_compat(from->si_lower);
3598 to->si_upper = ptr_to_compat(from->si_upper);
3599 break;
3600 case SIL_FAULT_PKUERR:
3601 to->si_addr = ptr_to_compat(from->si_addr);
3602 to->si_pkey = from->si_pkey;
3603 break;
3604 case SIL_FAULT_PERF_EVENT:
3605 to->si_addr = ptr_to_compat(from->si_addr);
3606 to->si_perf_data = from->si_perf_data;
3607 to->si_perf_type = from->si_perf_type;
3608 to->si_perf_flags = from->si_perf_flags;
3609 break;
3610 case SIL_CHLD:
3611 to->si_pid = from->si_pid;
3612 to->si_uid = from->si_uid;
3613 to->si_status = from->si_status;
3614 to->si_utime = from->si_utime;
3615 to->si_stime = from->si_stime;
3616 break;
3617 case SIL_RT:
3618 to->si_pid = from->si_pid;
3619 to->si_uid = from->si_uid;
3620 to->si_int = from->si_int;
3621 break;
3622 case SIL_SYS:
3623 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3624 to->si_syscall = from->si_syscall;
3625 to->si_arch = from->si_arch;
3626 break;
3627 }
3628}
3629
3630int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3631 const struct kernel_siginfo *from)
3632{
3633 struct compat_siginfo new;
3634
3635 copy_siginfo_to_external32(&new, from);
3636 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3637 return -EFAULT;
3638 return 0;
3639}
3640
3641static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3642 const struct compat_siginfo *from)
3643{
3644 clear_siginfo(to);
3645 to->si_signo = from->si_signo;
3646 to->si_errno = from->si_errno;
3647 to->si_code = from->si_code;
3648 switch(siginfo_layout(from->si_signo, from->si_code)) {
3649 case SIL_KILL:
3650 to->si_pid = from->si_pid;
3651 to->si_uid = from->si_uid;
3652 break;
3653 case SIL_TIMER:
3654 to->si_tid = from->si_tid;
3655 to->si_overrun = from->si_overrun;
3656 to->si_int = from->si_int;
3657 break;
3658 case SIL_POLL:
3659 to->si_band = from->si_band;
3660 to->si_fd = from->si_fd;
3661 break;
3662 case SIL_FAULT:
3663 to->si_addr = compat_ptr(from->si_addr);
3664 break;
3665 case SIL_FAULT_TRAPNO:
3666 to->si_addr = compat_ptr(from->si_addr);
3667 to->si_trapno = from->si_trapno;
3668 break;
3669 case SIL_FAULT_MCEERR:
3670 to->si_addr = compat_ptr(from->si_addr);
3671 to->si_addr_lsb = from->si_addr_lsb;
3672 break;
3673 case SIL_FAULT_BNDERR:
3674 to->si_addr = compat_ptr(from->si_addr);
3675 to->si_lower = compat_ptr(from->si_lower);
3676 to->si_upper = compat_ptr(from->si_upper);
3677 break;
3678 case SIL_FAULT_PKUERR:
3679 to->si_addr = compat_ptr(from->si_addr);
3680 to->si_pkey = from->si_pkey;
3681 break;
3682 case SIL_FAULT_PERF_EVENT:
3683 to->si_addr = compat_ptr(from->si_addr);
3684 to->si_perf_data = from->si_perf_data;
3685 to->si_perf_type = from->si_perf_type;
3686 to->si_perf_flags = from->si_perf_flags;
3687 break;
3688 case SIL_CHLD:
3689 to->si_pid = from->si_pid;
3690 to->si_uid = from->si_uid;
3691 to->si_status = from->si_status;
3692#ifdef CONFIG_X86_X32_ABI
3693 if (in_x32_syscall()) {
3694 to->si_utime = from->_sifields._sigchld_x32._utime;
3695 to->si_stime = from->_sifields._sigchld_x32._stime;
3696 } else
3697#endif
3698 {
3699 to->si_utime = from->si_utime;
3700 to->si_stime = from->si_stime;
3701 }
3702 break;
3703 case SIL_RT:
3704 to->si_pid = from->si_pid;
3705 to->si_uid = from->si_uid;
3706 to->si_int = from->si_int;
3707 break;
3708 case SIL_SYS:
3709 to->si_call_addr = compat_ptr(from->si_call_addr);
3710 to->si_syscall = from->si_syscall;
3711 to->si_arch = from->si_arch;
3712 break;
3713 }
3714 return 0;
3715}
3716
3717static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3718 const struct compat_siginfo __user *ufrom)
3719{
3720 struct compat_siginfo from;
3721
3722 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3723 return -EFAULT;
3724
3725 from.si_signo = signo;
3726 return post_copy_siginfo_from_user32(to, &from);
3727}
3728
3729int copy_siginfo_from_user32(struct kernel_siginfo *to,
3730 const struct compat_siginfo __user *ufrom)
3731{
3732 struct compat_siginfo from;
3733
3734 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3735 return -EFAULT;
3736
3737 return post_copy_siginfo_from_user32(to, &from);
3738}
3739#endif /* CONFIG_COMPAT */
3740
3741/**
3742 * do_sigtimedwait - wait for queued signals specified in @which
3743 * @which: queued signals to wait for
3744 * @info: if non-null, the signal's siginfo is returned here
3745 * @ts: upper bound on process time suspension
3746 */
3747static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3748 const struct timespec64 *ts)
3749{
3750 ktime_t *to = NULL, timeout = KTIME_MAX;
3751 struct task_struct *tsk = current;
3752 sigset_t mask = *which;
3753 enum pid_type type;
3754 int sig, ret = 0;
3755
3756 if (ts) {
3757 if (!timespec64_valid(ts))
3758 return -EINVAL;
3759 timeout = timespec64_to_ktime(*ts);
3760 to = &timeout;
3761 }
3762
3763 /*
3764 * Invert the set of allowed signals to get those we want to block.
3765 */
3766 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3767 signotset(&mask);
3768
3769 spin_lock_irq(&tsk->sighand->siglock);
3770 sig = dequeue_signal(&mask, info, &type);
3771 if (!sig && timeout) {
3772 /*
3773 * None ready, temporarily unblock those we're interested
3774 * while we are sleeping in so that we'll be awakened when
3775 * they arrive. Unblocking is always fine, we can avoid
3776 * set_current_blocked().
3777 */
3778 tsk->real_blocked = tsk->blocked;
3779 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3780 recalc_sigpending();
3781 spin_unlock_irq(&tsk->sighand->siglock);
3782
3783 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3784 ret = schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3785 HRTIMER_MODE_REL);
3786 spin_lock_irq(&tsk->sighand->siglock);
3787 __set_task_blocked(tsk, &tsk->real_blocked);
3788 sigemptyset(&tsk->real_blocked);
3789 sig = dequeue_signal(&mask, info, &type);
3790 }
3791 spin_unlock_irq(&tsk->sighand->siglock);
3792
3793 if (sig)
3794 return sig;
3795 return ret ? -EINTR : -EAGAIN;
3796}
3797
3798/**
3799 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3800 * in @uthese
3801 * @uthese: queued signals to wait for
3802 * @uinfo: if non-null, the signal's siginfo is returned here
3803 * @uts: upper bound on process time suspension
3804 * @sigsetsize: size of sigset_t type
3805 */
3806SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3807 siginfo_t __user *, uinfo,
3808 const struct __kernel_timespec __user *, uts,
3809 size_t, sigsetsize)
3810{
3811 sigset_t these;
3812 struct timespec64 ts;
3813 kernel_siginfo_t info;
3814 int ret;
3815
3816 /* XXX: Don't preclude handling different sized sigset_t's. */
3817 if (sigsetsize != sizeof(sigset_t))
3818 return -EINVAL;
3819
3820 if (copy_from_user(&these, uthese, sizeof(these)))
3821 return -EFAULT;
3822
3823 if (uts) {
3824 if (get_timespec64(&ts, uts))
3825 return -EFAULT;
3826 }
3827
3828 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3829
3830 if (ret > 0 && uinfo) {
3831 if (copy_siginfo_to_user(uinfo, &info))
3832 ret = -EFAULT;
3833 }
3834
3835 return ret;
3836}
3837
3838#ifdef CONFIG_COMPAT_32BIT_TIME
3839SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3840 siginfo_t __user *, uinfo,
3841 const struct old_timespec32 __user *, uts,
3842 size_t, sigsetsize)
3843{
3844 sigset_t these;
3845 struct timespec64 ts;
3846 kernel_siginfo_t info;
3847 int ret;
3848
3849 if (sigsetsize != sizeof(sigset_t))
3850 return -EINVAL;
3851
3852 if (copy_from_user(&these, uthese, sizeof(these)))
3853 return -EFAULT;
3854
3855 if (uts) {
3856 if (get_old_timespec32(&ts, uts))
3857 return -EFAULT;
3858 }
3859
3860 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3861
3862 if (ret > 0 && uinfo) {
3863 if (copy_siginfo_to_user(uinfo, &info))
3864 ret = -EFAULT;
3865 }
3866
3867 return ret;
3868}
3869#endif
3870
3871#ifdef CONFIG_COMPAT
3872COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3873 struct compat_siginfo __user *, uinfo,
3874 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3875{
3876 sigset_t s;
3877 struct timespec64 t;
3878 kernel_siginfo_t info;
3879 long ret;
3880
3881 if (sigsetsize != sizeof(sigset_t))
3882 return -EINVAL;
3883
3884 if (get_compat_sigset(&s, uthese))
3885 return -EFAULT;
3886
3887 if (uts) {
3888 if (get_timespec64(&t, uts))
3889 return -EFAULT;
3890 }
3891
3892 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3893
3894 if (ret > 0 && uinfo) {
3895 if (copy_siginfo_to_user32(uinfo, &info))
3896 ret = -EFAULT;
3897 }
3898
3899 return ret;
3900}
3901
3902#ifdef CONFIG_COMPAT_32BIT_TIME
3903COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3904 struct compat_siginfo __user *, uinfo,
3905 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3906{
3907 sigset_t s;
3908 struct timespec64 t;
3909 kernel_siginfo_t info;
3910 long ret;
3911
3912 if (sigsetsize != sizeof(sigset_t))
3913 return -EINVAL;
3914
3915 if (get_compat_sigset(&s, uthese))
3916 return -EFAULT;
3917
3918 if (uts) {
3919 if (get_old_timespec32(&t, uts))
3920 return -EFAULT;
3921 }
3922
3923 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3924
3925 if (ret > 0 && uinfo) {
3926 if (copy_siginfo_to_user32(uinfo, &info))
3927 ret = -EFAULT;
3928 }
3929
3930 return ret;
3931}
3932#endif
3933#endif
3934
3935static void prepare_kill_siginfo(int sig, struct kernel_siginfo *info,
3936 enum pid_type type)
3937{
3938 clear_siginfo(info);
3939 info->si_signo = sig;
3940 info->si_errno = 0;
3941 info->si_code = (type == PIDTYPE_PID) ? SI_TKILL : SI_USER;
3942 info->si_pid = task_tgid_vnr(current);
3943 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3944}
3945
3946/**
3947 * sys_kill - send a signal to a process
3948 * @pid: the PID of the process
3949 * @sig: signal to be sent
3950 */
3951SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3952{
3953 struct kernel_siginfo info;
3954
3955 prepare_kill_siginfo(sig, &info, PIDTYPE_TGID);
3956
3957 return kill_something_info(sig, &info, pid);
3958}
3959
3960/*
3961 * Verify that the signaler and signalee either are in the same pid namespace
3962 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3963 * namespace.
3964 */
3965static bool access_pidfd_pidns(struct pid *pid)
3966{
3967 struct pid_namespace *active = task_active_pid_ns(current);
3968 struct pid_namespace *p = ns_of_pid(pid);
3969
3970 for (;;) {
3971 if (!p)
3972 return false;
3973 if (p == active)
3974 break;
3975 p = p->parent;
3976 }
3977
3978 return true;
3979}
3980
3981static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3982 siginfo_t __user *info)
3983{
3984#ifdef CONFIG_COMPAT
3985 /*
3986 * Avoid hooking up compat syscalls and instead handle necessary
3987 * conversions here. Note, this is a stop-gap measure and should not be
3988 * considered a generic solution.
3989 */
3990 if (in_compat_syscall())
3991 return copy_siginfo_from_user32(
3992 kinfo, (struct compat_siginfo __user *)info);
3993#endif
3994 return copy_siginfo_from_user(kinfo, info);
3995}
3996
3997static struct pid *pidfd_to_pid(const struct file *file)
3998{
3999 struct pid *pid;
4000
4001 pid = pidfd_pid(file);
4002 if (!IS_ERR(pid))
4003 return pid;
4004
4005 return tgid_pidfd_to_pid(file);
4006}
4007
4008#define PIDFD_SEND_SIGNAL_FLAGS \
4009 (PIDFD_SIGNAL_THREAD | PIDFD_SIGNAL_THREAD_GROUP | \
4010 PIDFD_SIGNAL_PROCESS_GROUP)
4011
4012/**
4013 * sys_pidfd_send_signal - Signal a process through a pidfd
4014 * @pidfd: file descriptor of the process
4015 * @sig: signal to send
4016 * @info: signal info
4017 * @flags: future flags
4018 *
4019 * Send the signal to the thread group or to the individual thread depending
4020 * on PIDFD_THREAD.
4021 * In the future extension to @flags may be used to override the default scope
4022 * of @pidfd.
4023 *
4024 * Return: 0 on success, negative errno on failure
4025 */
4026SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
4027 siginfo_t __user *, info, unsigned int, flags)
4028{
4029 int ret;
4030 struct pid *pid;
4031 kernel_siginfo_t kinfo;
4032 enum pid_type type;
4033
4034 /* Enforce flags be set to 0 until we add an extension. */
4035 if (flags & ~PIDFD_SEND_SIGNAL_FLAGS)
4036 return -EINVAL;
4037
4038 /* Ensure that only a single signal scope determining flag is set. */
4039 if (hweight32(flags & PIDFD_SEND_SIGNAL_FLAGS) > 1)
4040 return -EINVAL;
4041
4042 CLASS(fd, f)(pidfd);
4043 if (fd_empty(f))
4044 return -EBADF;
4045
4046 /* Is this a pidfd? */
4047 pid = pidfd_to_pid(fd_file(f));
4048 if (IS_ERR(pid))
4049 return PTR_ERR(pid);
4050
4051 if (!access_pidfd_pidns(pid))
4052 return -EINVAL;
4053
4054 switch (flags) {
4055 case 0:
4056 /* Infer scope from the type of pidfd. */
4057 if (fd_file(f)->f_flags & PIDFD_THREAD)
4058 type = PIDTYPE_PID;
4059 else
4060 type = PIDTYPE_TGID;
4061 break;
4062 case PIDFD_SIGNAL_THREAD:
4063 type = PIDTYPE_PID;
4064 break;
4065 case PIDFD_SIGNAL_THREAD_GROUP:
4066 type = PIDTYPE_TGID;
4067 break;
4068 case PIDFD_SIGNAL_PROCESS_GROUP:
4069 type = PIDTYPE_PGID;
4070 break;
4071 }
4072
4073 if (info) {
4074 ret = copy_siginfo_from_user_any(&kinfo, info);
4075 if (unlikely(ret))
4076 return ret;
4077
4078 if (unlikely(sig != kinfo.si_signo))
4079 return -EINVAL;
4080
4081 /* Only allow sending arbitrary signals to yourself. */
4082 if ((task_pid(current) != pid || type > PIDTYPE_TGID) &&
4083 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
4084 return -EPERM;
4085 } else {
4086 prepare_kill_siginfo(sig, &kinfo, type);
4087 }
4088
4089 if (type == PIDTYPE_PGID)
4090 return kill_pgrp_info(sig, &kinfo, pid);
4091 else
4092 return kill_pid_info_type(sig, &kinfo, pid, type);
4093}
4094
4095static int
4096do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
4097{
4098 struct task_struct *p;
4099 int error = -ESRCH;
4100
4101 rcu_read_lock();
4102 p = find_task_by_vpid(pid);
4103 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
4104 error = check_kill_permission(sig, info, p);
4105 /*
4106 * The null signal is a permissions and process existence
4107 * probe. No signal is actually delivered.
4108 */
4109 if (!error && sig) {
4110 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
4111 /*
4112 * If lock_task_sighand() failed we pretend the task
4113 * dies after receiving the signal. The window is tiny,
4114 * and the signal is private anyway.
4115 */
4116 if (unlikely(error == -ESRCH))
4117 error = 0;
4118 }
4119 }
4120 rcu_read_unlock();
4121
4122 return error;
4123}
4124
4125static int do_tkill(pid_t tgid, pid_t pid, int sig)
4126{
4127 struct kernel_siginfo info;
4128
4129 prepare_kill_siginfo(sig, &info, PIDTYPE_PID);
4130
4131 return do_send_specific(tgid, pid, sig, &info);
4132}
4133
4134/**
4135 * sys_tgkill - send signal to one specific thread
4136 * @tgid: the thread group ID of the thread
4137 * @pid: the PID of the thread
4138 * @sig: signal to be sent
4139 *
4140 * This syscall also checks the @tgid and returns -ESRCH even if the PID
4141 * exists but it's not belonging to the target process anymore. This
4142 * method solves the problem of threads exiting and PIDs getting reused.
4143 */
4144SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
4145{
4146 /* This is only valid for single tasks */
4147 if (pid <= 0 || tgid <= 0)
4148 return -EINVAL;
4149
4150 return do_tkill(tgid, pid, sig);
4151}
4152
4153/**
4154 * sys_tkill - send signal to one specific task
4155 * @pid: the PID of the task
4156 * @sig: signal to be sent
4157 *
4158 * Send a signal to only one task, even if it's a CLONE_THREAD task.
4159 */
4160SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4161{
4162 /* This is only valid for single tasks */
4163 if (pid <= 0)
4164 return -EINVAL;
4165
4166 return do_tkill(0, pid, sig);
4167}
4168
4169static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4170{
4171 /* Not even root can pretend to send signals from the kernel.
4172 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4173 */
4174 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4175 (task_pid_vnr(current) != pid))
4176 return -EPERM;
4177
4178 /* POSIX.1b doesn't mention process groups. */
4179 return kill_proc_info(sig, info, pid);
4180}
4181
4182/**
4183 * sys_rt_sigqueueinfo - send signal information to a signal
4184 * @pid: the PID of the thread
4185 * @sig: signal to be sent
4186 * @uinfo: signal info to be sent
4187 */
4188SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4189 siginfo_t __user *, uinfo)
4190{
4191 kernel_siginfo_t info;
4192 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4193 if (unlikely(ret))
4194 return ret;
4195 return do_rt_sigqueueinfo(pid, sig, &info);
4196}
4197
4198#ifdef CONFIG_COMPAT
4199COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4200 compat_pid_t, pid,
4201 int, sig,
4202 struct compat_siginfo __user *, uinfo)
4203{
4204 kernel_siginfo_t info;
4205 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4206 if (unlikely(ret))
4207 return ret;
4208 return do_rt_sigqueueinfo(pid, sig, &info);
4209}
4210#endif
4211
4212static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4213{
4214 /* This is only valid for single tasks */
4215 if (pid <= 0 || tgid <= 0)
4216 return -EINVAL;
4217
4218 /* Not even root can pretend to send signals from the kernel.
4219 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4220 */
4221 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4222 (task_pid_vnr(current) != pid))
4223 return -EPERM;
4224
4225 return do_send_specific(tgid, pid, sig, info);
4226}
4227
4228SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4229 siginfo_t __user *, uinfo)
4230{
4231 kernel_siginfo_t info;
4232 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4233 if (unlikely(ret))
4234 return ret;
4235 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4236}
4237
4238#ifdef CONFIG_COMPAT
4239COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4240 compat_pid_t, tgid,
4241 compat_pid_t, pid,
4242 int, sig,
4243 struct compat_siginfo __user *, uinfo)
4244{
4245 kernel_siginfo_t info;
4246 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4247 if (unlikely(ret))
4248 return ret;
4249 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4250}
4251#endif
4252
4253/*
4254 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4255 */
4256void kernel_sigaction(int sig, __sighandler_t action)
4257{
4258 spin_lock_irq(¤t->sighand->siglock);
4259 current->sighand->action[sig - 1].sa.sa_handler = action;
4260 if (action == SIG_IGN) {
4261 sigset_t mask;
4262
4263 sigemptyset(&mask);
4264 sigaddset(&mask, sig);
4265
4266 flush_sigqueue_mask(current, &mask, ¤t->signal->shared_pending);
4267 flush_sigqueue_mask(current, &mask, ¤t->pending);
4268 recalc_sigpending();
4269 }
4270 spin_unlock_irq(¤t->sighand->siglock);
4271}
4272EXPORT_SYMBOL(kernel_sigaction);
4273
4274void __weak sigaction_compat_abi(struct k_sigaction *act,
4275 struct k_sigaction *oact)
4276{
4277}
4278
4279int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4280{
4281 struct task_struct *p = current, *t;
4282 struct k_sigaction *k;
4283 sigset_t mask;
4284
4285 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4286 return -EINVAL;
4287
4288 k = &p->sighand->action[sig-1];
4289
4290 spin_lock_irq(&p->sighand->siglock);
4291 if (k->sa.sa_flags & SA_IMMUTABLE) {
4292 spin_unlock_irq(&p->sighand->siglock);
4293 return -EINVAL;
4294 }
4295 if (oact)
4296 *oact = *k;
4297
4298 /*
4299 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4300 * e.g. by having an architecture use the bit in their uapi.
4301 */
4302 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4303
4304 /*
4305 * Clear unknown flag bits in order to allow userspace to detect missing
4306 * support for flag bits and to allow the kernel to use non-uapi bits
4307 * internally.
4308 */
4309 if (act)
4310 act->sa.sa_flags &= UAPI_SA_FLAGS;
4311 if (oact)
4312 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4313
4314 sigaction_compat_abi(act, oact);
4315
4316 if (act) {
4317 bool was_ignored = k->sa.sa_handler == SIG_IGN;
4318
4319 sigdelsetmask(&act->sa.sa_mask,
4320 sigmask(SIGKILL) | sigmask(SIGSTOP));
4321 *k = *act;
4322 /*
4323 * POSIX 3.3.1.3:
4324 * "Setting a signal action to SIG_IGN for a signal that is
4325 * pending shall cause the pending signal to be discarded,
4326 * whether or not it is blocked."
4327 *
4328 * "Setting a signal action to SIG_DFL for a signal that is
4329 * pending and whose default action is to ignore the signal
4330 * (for example, SIGCHLD), shall cause the pending signal to
4331 * be discarded, whether or not it is blocked"
4332 */
4333 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4334 sigemptyset(&mask);
4335 sigaddset(&mask, sig);
4336 flush_sigqueue_mask(p, &mask, &p->signal->shared_pending);
4337 for_each_thread(p, t)
4338 flush_sigqueue_mask(p, &mask, &t->pending);
4339 } else if (was_ignored) {
4340 posixtimer_sig_unignore(p, sig);
4341 }
4342 }
4343
4344 spin_unlock_irq(&p->sighand->siglock);
4345 return 0;
4346}
4347
4348#ifdef CONFIG_DYNAMIC_SIGFRAME
4349static inline void sigaltstack_lock(void)
4350 __acquires(¤t->sighand->siglock)
4351{
4352 spin_lock_irq(¤t->sighand->siglock);
4353}
4354
4355static inline void sigaltstack_unlock(void)
4356 __releases(¤t->sighand->siglock)
4357{
4358 spin_unlock_irq(¤t->sighand->siglock);
4359}
4360#else
4361static inline void sigaltstack_lock(void) { }
4362static inline void sigaltstack_unlock(void) { }
4363#endif
4364
4365static int
4366do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4367 size_t min_ss_size)
4368{
4369 struct task_struct *t = current;
4370 int ret = 0;
4371
4372 if (oss) {
4373 memset(oss, 0, sizeof(stack_t));
4374 oss->ss_sp = (void __user *) t->sas_ss_sp;
4375 oss->ss_size = t->sas_ss_size;
4376 oss->ss_flags = sas_ss_flags(sp) |
4377 (current->sas_ss_flags & SS_FLAG_BITS);
4378 }
4379
4380 if (ss) {
4381 void __user *ss_sp = ss->ss_sp;
4382 size_t ss_size = ss->ss_size;
4383 unsigned ss_flags = ss->ss_flags;
4384 int ss_mode;
4385
4386 if (unlikely(on_sig_stack(sp)))
4387 return -EPERM;
4388
4389 ss_mode = ss_flags & ~SS_FLAG_BITS;
4390 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4391 ss_mode != 0))
4392 return -EINVAL;
4393
4394 /*
4395 * Return before taking any locks if no actual
4396 * sigaltstack changes were requested.
4397 */
4398 if (t->sas_ss_sp == (unsigned long)ss_sp &&
4399 t->sas_ss_size == ss_size &&
4400 t->sas_ss_flags == ss_flags)
4401 return 0;
4402
4403 sigaltstack_lock();
4404 if (ss_mode == SS_DISABLE) {
4405 ss_size = 0;
4406 ss_sp = NULL;
4407 } else {
4408 if (unlikely(ss_size < min_ss_size))
4409 ret = -ENOMEM;
4410 if (!sigaltstack_size_valid(ss_size))
4411 ret = -ENOMEM;
4412 }
4413 if (!ret) {
4414 t->sas_ss_sp = (unsigned long) ss_sp;
4415 t->sas_ss_size = ss_size;
4416 t->sas_ss_flags = ss_flags;
4417 }
4418 sigaltstack_unlock();
4419 }
4420 return ret;
4421}
4422
4423SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4424{
4425 stack_t new, old;
4426 int err;
4427 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4428 return -EFAULT;
4429 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4430 current_user_stack_pointer(),
4431 MINSIGSTKSZ);
4432 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4433 err = -EFAULT;
4434 return err;
4435}
4436
4437int restore_altstack(const stack_t __user *uss)
4438{
4439 stack_t new;
4440 if (copy_from_user(&new, uss, sizeof(stack_t)))
4441 return -EFAULT;
4442 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4443 MINSIGSTKSZ);
4444 /* squash all but EFAULT for now */
4445 return 0;
4446}
4447
4448int __save_altstack(stack_t __user *uss, unsigned long sp)
4449{
4450 struct task_struct *t = current;
4451 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4452 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4453 __put_user(t->sas_ss_size, &uss->ss_size);
4454 return err;
4455}
4456
4457#ifdef CONFIG_COMPAT
4458static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4459 compat_stack_t __user *uoss_ptr)
4460{
4461 stack_t uss, uoss;
4462 int ret;
4463
4464 if (uss_ptr) {
4465 compat_stack_t uss32;
4466 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4467 return -EFAULT;
4468 uss.ss_sp = compat_ptr(uss32.ss_sp);
4469 uss.ss_flags = uss32.ss_flags;
4470 uss.ss_size = uss32.ss_size;
4471 }
4472 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4473 compat_user_stack_pointer(),
4474 COMPAT_MINSIGSTKSZ);
4475 if (ret >= 0 && uoss_ptr) {
4476 compat_stack_t old;
4477 memset(&old, 0, sizeof(old));
4478 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4479 old.ss_flags = uoss.ss_flags;
4480 old.ss_size = uoss.ss_size;
4481 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4482 ret = -EFAULT;
4483 }
4484 return ret;
4485}
4486
4487COMPAT_SYSCALL_DEFINE2(sigaltstack,
4488 const compat_stack_t __user *, uss_ptr,
4489 compat_stack_t __user *, uoss_ptr)
4490{
4491 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4492}
4493
4494int compat_restore_altstack(const compat_stack_t __user *uss)
4495{
4496 int err = do_compat_sigaltstack(uss, NULL);
4497 /* squash all but -EFAULT for now */
4498 return err == -EFAULT ? err : 0;
4499}
4500
4501int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4502{
4503 int err;
4504 struct task_struct *t = current;
4505 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4506 &uss->ss_sp) |
4507 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4508 __put_user(t->sas_ss_size, &uss->ss_size);
4509 return err;
4510}
4511#endif
4512
4513#ifdef __ARCH_WANT_SYS_SIGPENDING
4514
4515/**
4516 * sys_sigpending - examine pending signals
4517 * @uset: where mask of pending signal is returned
4518 */
4519SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4520{
4521 sigset_t set;
4522
4523 if (sizeof(old_sigset_t) > sizeof(*uset))
4524 return -EINVAL;
4525
4526 do_sigpending(&set);
4527
4528 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4529 return -EFAULT;
4530
4531 return 0;
4532}
4533
4534#ifdef CONFIG_COMPAT
4535COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4536{
4537 sigset_t set;
4538
4539 do_sigpending(&set);
4540
4541 return put_user(set.sig[0], set32);
4542}
4543#endif
4544
4545#endif
4546
4547#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4548/**
4549 * sys_sigprocmask - examine and change blocked signals
4550 * @how: whether to add, remove, or set signals
4551 * @nset: signals to add or remove (if non-null)
4552 * @oset: previous value of signal mask if non-null
4553 *
4554 * Some platforms have their own version with special arguments;
4555 * others support only sys_rt_sigprocmask.
4556 */
4557
4558SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4559 old_sigset_t __user *, oset)
4560{
4561 old_sigset_t old_set, new_set;
4562 sigset_t new_blocked;
4563
4564 old_set = current->blocked.sig[0];
4565
4566 if (nset) {
4567 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4568 return -EFAULT;
4569
4570 new_blocked = current->blocked;
4571
4572 switch (how) {
4573 case SIG_BLOCK:
4574 sigaddsetmask(&new_blocked, new_set);
4575 break;
4576 case SIG_UNBLOCK:
4577 sigdelsetmask(&new_blocked, new_set);
4578 break;
4579 case SIG_SETMASK:
4580 new_blocked.sig[0] = new_set;
4581 break;
4582 default:
4583 return -EINVAL;
4584 }
4585
4586 set_current_blocked(&new_blocked);
4587 }
4588
4589 if (oset) {
4590 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4591 return -EFAULT;
4592 }
4593
4594 return 0;
4595}
4596#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4597
4598#ifndef CONFIG_ODD_RT_SIGACTION
4599/**
4600 * sys_rt_sigaction - alter an action taken by a process
4601 * @sig: signal to be sent
4602 * @act: new sigaction
4603 * @oact: used to save the previous sigaction
4604 * @sigsetsize: size of sigset_t type
4605 */
4606SYSCALL_DEFINE4(rt_sigaction, int, sig,
4607 const struct sigaction __user *, act,
4608 struct sigaction __user *, oact,
4609 size_t, sigsetsize)
4610{
4611 struct k_sigaction new_sa, old_sa;
4612 int ret;
4613
4614 /* XXX: Don't preclude handling different sized sigset_t's. */
4615 if (sigsetsize != sizeof(sigset_t))
4616 return -EINVAL;
4617
4618 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4619 return -EFAULT;
4620
4621 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4622 if (ret)
4623 return ret;
4624
4625 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4626 return -EFAULT;
4627
4628 return 0;
4629}
4630#ifdef CONFIG_COMPAT
4631COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4632 const struct compat_sigaction __user *, act,
4633 struct compat_sigaction __user *, oact,
4634 compat_size_t, sigsetsize)
4635{
4636 struct k_sigaction new_ka, old_ka;
4637#ifdef __ARCH_HAS_SA_RESTORER
4638 compat_uptr_t restorer;
4639#endif
4640 int ret;
4641
4642 /* XXX: Don't preclude handling different sized sigset_t's. */
4643 if (sigsetsize != sizeof(compat_sigset_t))
4644 return -EINVAL;
4645
4646 if (act) {
4647 compat_uptr_t handler;
4648 ret = get_user(handler, &act->sa_handler);
4649 new_ka.sa.sa_handler = compat_ptr(handler);
4650#ifdef __ARCH_HAS_SA_RESTORER
4651 ret |= get_user(restorer, &act->sa_restorer);
4652 new_ka.sa.sa_restorer = compat_ptr(restorer);
4653#endif
4654 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4655 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4656 if (ret)
4657 return -EFAULT;
4658 }
4659
4660 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4661 if (!ret && oact) {
4662 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4663 &oact->sa_handler);
4664 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4665 sizeof(oact->sa_mask));
4666 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4667#ifdef __ARCH_HAS_SA_RESTORER
4668 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4669 &oact->sa_restorer);
4670#endif
4671 }
4672 return ret;
4673}
4674#endif
4675#endif /* !CONFIG_ODD_RT_SIGACTION */
4676
4677#ifdef CONFIG_OLD_SIGACTION
4678SYSCALL_DEFINE3(sigaction, int, sig,
4679 const struct old_sigaction __user *, act,
4680 struct old_sigaction __user *, oact)
4681{
4682 struct k_sigaction new_ka, old_ka;
4683 int ret;
4684
4685 if (act) {
4686 old_sigset_t mask;
4687 if (!access_ok(act, sizeof(*act)) ||
4688 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4689 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4690 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4691 __get_user(mask, &act->sa_mask))
4692 return -EFAULT;
4693#ifdef __ARCH_HAS_KA_RESTORER
4694 new_ka.ka_restorer = NULL;
4695#endif
4696 siginitset(&new_ka.sa.sa_mask, mask);
4697 }
4698
4699 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4700
4701 if (!ret && oact) {
4702 if (!access_ok(oact, sizeof(*oact)) ||
4703 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4704 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4705 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4706 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4707 return -EFAULT;
4708 }
4709
4710 return ret;
4711}
4712#endif
4713#ifdef CONFIG_COMPAT_OLD_SIGACTION
4714COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4715 const struct compat_old_sigaction __user *, act,
4716 struct compat_old_sigaction __user *, oact)
4717{
4718 struct k_sigaction new_ka, old_ka;
4719 int ret;
4720 compat_old_sigset_t mask;
4721 compat_uptr_t handler, restorer;
4722
4723 if (act) {
4724 if (!access_ok(act, sizeof(*act)) ||
4725 __get_user(handler, &act->sa_handler) ||
4726 __get_user(restorer, &act->sa_restorer) ||
4727 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4728 __get_user(mask, &act->sa_mask))
4729 return -EFAULT;
4730
4731#ifdef __ARCH_HAS_KA_RESTORER
4732 new_ka.ka_restorer = NULL;
4733#endif
4734 new_ka.sa.sa_handler = compat_ptr(handler);
4735 new_ka.sa.sa_restorer = compat_ptr(restorer);
4736 siginitset(&new_ka.sa.sa_mask, mask);
4737 }
4738
4739 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4740
4741 if (!ret && oact) {
4742 if (!access_ok(oact, sizeof(*oact)) ||
4743 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4744 &oact->sa_handler) ||
4745 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4746 &oact->sa_restorer) ||
4747 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4748 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4749 return -EFAULT;
4750 }
4751 return ret;
4752}
4753#endif
4754
4755#ifdef CONFIG_SGETMASK_SYSCALL
4756
4757/*
4758 * For backwards compatibility. Functionality superseded by sigprocmask.
4759 */
4760SYSCALL_DEFINE0(sgetmask)
4761{
4762 /* SMP safe */
4763 return current->blocked.sig[0];
4764}
4765
4766SYSCALL_DEFINE1(ssetmask, int, newmask)
4767{
4768 int old = current->blocked.sig[0];
4769 sigset_t newset;
4770
4771 siginitset(&newset, newmask);
4772 set_current_blocked(&newset);
4773
4774 return old;
4775}
4776#endif /* CONFIG_SGETMASK_SYSCALL */
4777
4778#ifdef __ARCH_WANT_SYS_SIGNAL
4779/*
4780 * For backwards compatibility. Functionality superseded by sigaction.
4781 */
4782SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4783{
4784 struct k_sigaction new_sa, old_sa;
4785 int ret;
4786
4787 new_sa.sa.sa_handler = handler;
4788 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4789 sigemptyset(&new_sa.sa.sa_mask);
4790
4791 ret = do_sigaction(sig, &new_sa, &old_sa);
4792
4793 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4794}
4795#endif /* __ARCH_WANT_SYS_SIGNAL */
4796
4797#ifdef __ARCH_WANT_SYS_PAUSE
4798
4799SYSCALL_DEFINE0(pause)
4800{
4801 while (!signal_pending(current)) {
4802 __set_current_state(TASK_INTERRUPTIBLE);
4803 schedule();
4804 }
4805 return -ERESTARTNOHAND;
4806}
4807
4808#endif
4809
4810static int sigsuspend(sigset_t *set)
4811{
4812 current->saved_sigmask = current->blocked;
4813 set_current_blocked(set);
4814
4815 while (!signal_pending(current)) {
4816 __set_current_state(TASK_INTERRUPTIBLE);
4817 schedule();
4818 }
4819 set_restore_sigmask();
4820 return -ERESTARTNOHAND;
4821}
4822
4823/**
4824 * sys_rt_sigsuspend - replace the signal mask for a value with the
4825 * @unewset value until a signal is received
4826 * @unewset: new signal mask value
4827 * @sigsetsize: size of sigset_t type
4828 */
4829SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4830{
4831 sigset_t newset;
4832
4833 /* XXX: Don't preclude handling different sized sigset_t's. */
4834 if (sigsetsize != sizeof(sigset_t))
4835 return -EINVAL;
4836
4837 if (copy_from_user(&newset, unewset, sizeof(newset)))
4838 return -EFAULT;
4839 return sigsuspend(&newset);
4840}
4841
4842#ifdef CONFIG_COMPAT
4843COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4844{
4845 sigset_t newset;
4846
4847 /* XXX: Don't preclude handling different sized sigset_t's. */
4848 if (sigsetsize != sizeof(sigset_t))
4849 return -EINVAL;
4850
4851 if (get_compat_sigset(&newset, unewset))
4852 return -EFAULT;
4853 return sigsuspend(&newset);
4854}
4855#endif
4856
4857#ifdef CONFIG_OLD_SIGSUSPEND
4858SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4859{
4860 sigset_t blocked;
4861 siginitset(&blocked, mask);
4862 return sigsuspend(&blocked);
4863}
4864#endif
4865#ifdef CONFIG_OLD_SIGSUSPEND3
4866SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4867{
4868 sigset_t blocked;
4869 siginitset(&blocked, mask);
4870 return sigsuspend(&blocked);
4871}
4872#endif
4873
4874__weak const char *arch_vma_name(struct vm_area_struct *vma)
4875{
4876 return NULL;
4877}
4878
4879static inline void siginfo_buildtime_checks(void)
4880{
4881 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4882
4883 /* Verify the offsets in the two siginfos match */
4884#define CHECK_OFFSET(field) \
4885 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4886
4887 /* kill */
4888 CHECK_OFFSET(si_pid);
4889 CHECK_OFFSET(si_uid);
4890
4891 /* timer */
4892 CHECK_OFFSET(si_tid);
4893 CHECK_OFFSET(si_overrun);
4894 CHECK_OFFSET(si_value);
4895
4896 /* rt */
4897 CHECK_OFFSET(si_pid);
4898 CHECK_OFFSET(si_uid);
4899 CHECK_OFFSET(si_value);
4900
4901 /* sigchld */
4902 CHECK_OFFSET(si_pid);
4903 CHECK_OFFSET(si_uid);
4904 CHECK_OFFSET(si_status);
4905 CHECK_OFFSET(si_utime);
4906 CHECK_OFFSET(si_stime);
4907
4908 /* sigfault */
4909 CHECK_OFFSET(si_addr);
4910 CHECK_OFFSET(si_trapno);
4911 CHECK_OFFSET(si_addr_lsb);
4912 CHECK_OFFSET(si_lower);
4913 CHECK_OFFSET(si_upper);
4914 CHECK_OFFSET(si_pkey);
4915 CHECK_OFFSET(si_perf_data);
4916 CHECK_OFFSET(si_perf_type);
4917 CHECK_OFFSET(si_perf_flags);
4918
4919 /* sigpoll */
4920 CHECK_OFFSET(si_band);
4921 CHECK_OFFSET(si_fd);
4922
4923 /* sigsys */
4924 CHECK_OFFSET(si_call_addr);
4925 CHECK_OFFSET(si_syscall);
4926 CHECK_OFFSET(si_arch);
4927#undef CHECK_OFFSET
4928
4929 /* usb asyncio */
4930 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4931 offsetof(struct siginfo, si_addr));
4932 if (sizeof(int) == sizeof(void __user *)) {
4933 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4934 sizeof(void __user *));
4935 } else {
4936 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4937 sizeof_field(struct siginfo, si_uid)) !=
4938 sizeof(void __user *));
4939 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4940 offsetof(struct siginfo, si_uid));
4941 }
4942#ifdef CONFIG_COMPAT
4943 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4944 offsetof(struct compat_siginfo, si_addr));
4945 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4946 sizeof(compat_uptr_t));
4947 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4948 sizeof_field(struct siginfo, si_pid));
4949#endif
4950}
4951
4952#if defined(CONFIG_SYSCTL)
4953static struct ctl_table signal_debug_table[] = {
4954#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4955 {
4956 .procname = "exception-trace",
4957 .data = &show_unhandled_signals,
4958 .maxlen = sizeof(int),
4959 .mode = 0644,
4960 .proc_handler = proc_dointvec
4961 },
4962#endif
4963};
4964
4965static int __init init_signal_sysctls(void)
4966{
4967 register_sysctl_init("debug", signal_debug_table);
4968 return 0;
4969}
4970early_initcall(init_signal_sysctls);
4971#endif /* CONFIG_SYSCTL */
4972
4973void __init signals_init(void)
4974{
4975 siginfo_buildtime_checks();
4976
4977 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4978}
4979
4980#ifdef CONFIG_KGDB_KDB
4981#include <linux/kdb.h>
4982/*
4983 * kdb_send_sig - Allows kdb to send signals without exposing
4984 * signal internals. This function checks if the required locks are
4985 * available before calling the main signal code, to avoid kdb
4986 * deadlocks.
4987 */
4988void kdb_send_sig(struct task_struct *t, int sig)
4989{
4990 static struct task_struct *kdb_prev_t;
4991 int new_t, ret;
4992 if (!spin_trylock(&t->sighand->siglock)) {
4993 kdb_printf("Can't do kill command now.\n"
4994 "The sigmask lock is held somewhere else in "
4995 "kernel, try again later\n");
4996 return;
4997 }
4998 new_t = kdb_prev_t != t;
4999 kdb_prev_t = t;
5000 if (!task_is_running(t) && new_t) {
5001 spin_unlock(&t->sighand->siglock);
5002 kdb_printf("Process is not RUNNING, sending a signal from "
5003 "kdb risks deadlock\n"
5004 "on the run queue locks. "
5005 "The signal has _not_ been sent.\n"
5006 "Reissue the kill command if you want to risk "
5007 "the deadlock.\n");
5008 return;
5009 }
5010 ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
5011 spin_unlock(&t->sighand->siglock);
5012 if (ret)
5013 kdb_printf("Fail to deliver Signal %d to process %d.\n",
5014 sig, t->pid);
5015 else
5016 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
5017}
5018#endif /* CONFIG_KGDB_KDB */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
12 */
13
14#include <linux/slab.h>
15#include <linux/export.h>
16#include <linux/init.h>
17#include <linux/sched/mm.h>
18#include <linux/sched/user.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/sched/cputime.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/proc_fs.h>
26#include <linux/tty.h>
27#include <linux/binfmts.h>
28#include <linux/coredump.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/ptrace.h>
32#include <linux/signal.h>
33#include <linux/signalfd.h>
34#include <linux/ratelimit.h>
35#include <linux/tracehook.h>
36#include <linux/capability.h>
37#include <linux/freezer.h>
38#include <linux/pid_namespace.h>
39#include <linux/nsproxy.h>
40#include <linux/user_namespace.h>
41#include <linux/uprobes.h>
42#include <linux/compat.h>
43#include <linux/cn_proc.h>
44#include <linux/compiler.h>
45#include <linux/posix-timers.h>
46#include <linux/cgroup.h>
47#include <linux/audit.h>
48
49#define CREATE_TRACE_POINTS
50#include <trace/events/signal.h>
51
52#include <asm/param.h>
53#include <linux/uaccess.h>
54#include <asm/unistd.h>
55#include <asm/siginfo.h>
56#include <asm/cacheflush.h>
57
58/*
59 * SLAB caches for signal bits.
60 */
61
62static struct kmem_cache *sigqueue_cachep;
63
64int print_fatal_signals __read_mostly;
65
66static void __user *sig_handler(struct task_struct *t, int sig)
67{
68 return t->sighand->action[sig - 1].sa.sa_handler;
69}
70
71static inline bool sig_handler_ignored(void __user *handler, int sig)
72{
73 /* Is it explicitly or implicitly ignored? */
74 return handler == SIG_IGN ||
75 (handler == SIG_DFL && sig_kernel_ignore(sig));
76}
77
78static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
79{
80 void __user *handler;
81
82 handler = sig_handler(t, sig);
83
84 /* SIGKILL and SIGSTOP may not be sent to the global init */
85 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
86 return true;
87
88 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
89 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
90 return true;
91
92 /* Only allow kernel generated signals to this kthread */
93 if (unlikely((t->flags & PF_KTHREAD) &&
94 (handler == SIG_KTHREAD_KERNEL) && !force))
95 return true;
96
97 return sig_handler_ignored(handler, sig);
98}
99
100static bool sig_ignored(struct task_struct *t, int sig, bool force)
101{
102 /*
103 * Blocked signals are never ignored, since the
104 * signal handler may change by the time it is
105 * unblocked.
106 */
107 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
108 return false;
109
110 /*
111 * Tracers may want to know about even ignored signal unless it
112 * is SIGKILL which can't be reported anyway but can be ignored
113 * by SIGNAL_UNKILLABLE task.
114 */
115 if (t->ptrace && sig != SIGKILL)
116 return false;
117
118 return sig_task_ignored(t, sig, force);
119}
120
121/*
122 * Re-calculate pending state from the set of locally pending
123 * signals, globally pending signals, and blocked signals.
124 */
125static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
126{
127 unsigned long ready;
128 long i;
129
130 switch (_NSIG_WORDS) {
131 default:
132 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
133 ready |= signal->sig[i] &~ blocked->sig[i];
134 break;
135
136 case 4: ready = signal->sig[3] &~ blocked->sig[3];
137 ready |= signal->sig[2] &~ blocked->sig[2];
138 ready |= signal->sig[1] &~ blocked->sig[1];
139 ready |= signal->sig[0] &~ blocked->sig[0];
140 break;
141
142 case 2: ready = signal->sig[1] &~ blocked->sig[1];
143 ready |= signal->sig[0] &~ blocked->sig[0];
144 break;
145
146 case 1: ready = signal->sig[0] &~ blocked->sig[0];
147 }
148 return ready != 0;
149}
150
151#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
152
153static bool recalc_sigpending_tsk(struct task_struct *t)
154{
155 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
156 PENDING(&t->pending, &t->blocked) ||
157 PENDING(&t->signal->shared_pending, &t->blocked) ||
158 cgroup_task_frozen(t)) {
159 set_tsk_thread_flag(t, TIF_SIGPENDING);
160 return true;
161 }
162
163 /*
164 * We must never clear the flag in another thread, or in current
165 * when it's possible the current syscall is returning -ERESTART*.
166 * So we don't clear it here, and only callers who know they should do.
167 */
168 return false;
169}
170
171/*
172 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
173 * This is superfluous when called on current, the wakeup is a harmless no-op.
174 */
175void recalc_sigpending_and_wake(struct task_struct *t)
176{
177 if (recalc_sigpending_tsk(t))
178 signal_wake_up(t, 0);
179}
180
181void recalc_sigpending(void)
182{
183 if (!recalc_sigpending_tsk(current) && !freezing(current))
184 clear_thread_flag(TIF_SIGPENDING);
185
186}
187EXPORT_SYMBOL(recalc_sigpending);
188
189void calculate_sigpending(void)
190{
191 /* Have any signals or users of TIF_SIGPENDING been delayed
192 * until after fork?
193 */
194 spin_lock_irq(¤t->sighand->siglock);
195 set_tsk_thread_flag(current, TIF_SIGPENDING);
196 recalc_sigpending();
197 spin_unlock_irq(¤t->sighand->siglock);
198}
199
200/* Given the mask, find the first available signal that should be serviced. */
201
202#define SYNCHRONOUS_MASK \
203 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
204 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
205
206int next_signal(struct sigpending *pending, sigset_t *mask)
207{
208 unsigned long i, *s, *m, x;
209 int sig = 0;
210
211 s = pending->signal.sig;
212 m = mask->sig;
213
214 /*
215 * Handle the first word specially: it contains the
216 * synchronous signals that need to be dequeued first.
217 */
218 x = *s &~ *m;
219 if (x) {
220 if (x & SYNCHRONOUS_MASK)
221 x &= SYNCHRONOUS_MASK;
222 sig = ffz(~x) + 1;
223 return sig;
224 }
225
226 switch (_NSIG_WORDS) {
227 default:
228 for (i = 1; i < _NSIG_WORDS; ++i) {
229 x = *++s &~ *++m;
230 if (!x)
231 continue;
232 sig = ffz(~x) + i*_NSIG_BPW + 1;
233 break;
234 }
235 break;
236
237 case 2:
238 x = s[1] &~ m[1];
239 if (!x)
240 break;
241 sig = ffz(~x) + _NSIG_BPW + 1;
242 break;
243
244 case 1:
245 /* Nothing to do */
246 break;
247 }
248
249 return sig;
250}
251
252static inline void print_dropped_signal(int sig)
253{
254 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
255
256 if (!print_fatal_signals)
257 return;
258
259 if (!__ratelimit(&ratelimit_state))
260 return;
261
262 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
263 current->comm, current->pid, sig);
264}
265
266/**
267 * task_set_jobctl_pending - set jobctl pending bits
268 * @task: target task
269 * @mask: pending bits to set
270 *
271 * Clear @mask from @task->jobctl. @mask must be subset of
272 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
273 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
274 * cleared. If @task is already being killed or exiting, this function
275 * becomes noop.
276 *
277 * CONTEXT:
278 * Must be called with @task->sighand->siglock held.
279 *
280 * RETURNS:
281 * %true if @mask is set, %false if made noop because @task was dying.
282 */
283bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
284{
285 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
286 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
287 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
288
289 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
290 return false;
291
292 if (mask & JOBCTL_STOP_SIGMASK)
293 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
294
295 task->jobctl |= mask;
296 return true;
297}
298
299/**
300 * task_clear_jobctl_trapping - clear jobctl trapping bit
301 * @task: target task
302 *
303 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
304 * Clear it and wake up the ptracer. Note that we don't need any further
305 * locking. @task->siglock guarantees that @task->parent points to the
306 * ptracer.
307 *
308 * CONTEXT:
309 * Must be called with @task->sighand->siglock held.
310 */
311void task_clear_jobctl_trapping(struct task_struct *task)
312{
313 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
314 task->jobctl &= ~JOBCTL_TRAPPING;
315 smp_mb(); /* advised by wake_up_bit() */
316 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
317 }
318}
319
320/**
321 * task_clear_jobctl_pending - clear jobctl pending bits
322 * @task: target task
323 * @mask: pending bits to clear
324 *
325 * Clear @mask from @task->jobctl. @mask must be subset of
326 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
327 * STOP bits are cleared together.
328 *
329 * If clearing of @mask leaves no stop or trap pending, this function calls
330 * task_clear_jobctl_trapping().
331 *
332 * CONTEXT:
333 * Must be called with @task->sighand->siglock held.
334 */
335void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
336{
337 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
338
339 if (mask & JOBCTL_STOP_PENDING)
340 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
341
342 task->jobctl &= ~mask;
343
344 if (!(task->jobctl & JOBCTL_PENDING_MASK))
345 task_clear_jobctl_trapping(task);
346}
347
348/**
349 * task_participate_group_stop - participate in a group stop
350 * @task: task participating in a group stop
351 *
352 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
353 * Group stop states are cleared and the group stop count is consumed if
354 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
355 * stop, the appropriate `SIGNAL_*` flags are set.
356 *
357 * CONTEXT:
358 * Must be called with @task->sighand->siglock held.
359 *
360 * RETURNS:
361 * %true if group stop completion should be notified to the parent, %false
362 * otherwise.
363 */
364static bool task_participate_group_stop(struct task_struct *task)
365{
366 struct signal_struct *sig = task->signal;
367 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
368
369 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
370
371 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
372
373 if (!consume)
374 return false;
375
376 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
377 sig->group_stop_count--;
378
379 /*
380 * Tell the caller to notify completion iff we are entering into a
381 * fresh group stop. Read comment in do_signal_stop() for details.
382 */
383 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
384 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
385 return true;
386 }
387 return false;
388}
389
390void task_join_group_stop(struct task_struct *task)
391{
392 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
393 struct signal_struct *sig = current->signal;
394
395 if (sig->group_stop_count) {
396 sig->group_stop_count++;
397 mask |= JOBCTL_STOP_CONSUME;
398 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
399 return;
400
401 /* Have the new thread join an on-going signal group stop */
402 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
403}
404
405/*
406 * allocate a new signal queue record
407 * - this may be called without locks if and only if t == current, otherwise an
408 * appropriate lock must be held to stop the target task from exiting
409 */
410static struct sigqueue *
411__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
412 int override_rlimit, const unsigned int sigqueue_flags)
413{
414 struct sigqueue *q = NULL;
415 struct ucounts *ucounts = NULL;
416 long sigpending;
417
418 /*
419 * Protect access to @t credentials. This can go away when all
420 * callers hold rcu read lock.
421 *
422 * NOTE! A pending signal will hold on to the user refcount,
423 * and we get/put the refcount only when the sigpending count
424 * changes from/to zero.
425 */
426 rcu_read_lock();
427 ucounts = task_ucounts(t);
428 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
429 rcu_read_unlock();
430 if (!sigpending)
431 return NULL;
432
433 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
434 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
435 } else {
436 print_dropped_signal(sig);
437 }
438
439 if (unlikely(q == NULL)) {
440 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
441 } else {
442 INIT_LIST_HEAD(&q->list);
443 q->flags = sigqueue_flags;
444 q->ucounts = ucounts;
445 }
446 return q;
447}
448
449static void __sigqueue_free(struct sigqueue *q)
450{
451 if (q->flags & SIGQUEUE_PREALLOC)
452 return;
453 if (q->ucounts) {
454 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
455 q->ucounts = NULL;
456 }
457 kmem_cache_free(sigqueue_cachep, q);
458}
459
460void flush_sigqueue(struct sigpending *queue)
461{
462 struct sigqueue *q;
463
464 sigemptyset(&queue->signal);
465 while (!list_empty(&queue->list)) {
466 q = list_entry(queue->list.next, struct sigqueue , list);
467 list_del_init(&q->list);
468 __sigqueue_free(q);
469 }
470}
471
472/*
473 * Flush all pending signals for this kthread.
474 */
475void flush_signals(struct task_struct *t)
476{
477 unsigned long flags;
478
479 spin_lock_irqsave(&t->sighand->siglock, flags);
480 clear_tsk_thread_flag(t, TIF_SIGPENDING);
481 flush_sigqueue(&t->pending);
482 flush_sigqueue(&t->signal->shared_pending);
483 spin_unlock_irqrestore(&t->sighand->siglock, flags);
484}
485EXPORT_SYMBOL(flush_signals);
486
487#ifdef CONFIG_POSIX_TIMERS
488static void __flush_itimer_signals(struct sigpending *pending)
489{
490 sigset_t signal, retain;
491 struct sigqueue *q, *n;
492
493 signal = pending->signal;
494 sigemptyset(&retain);
495
496 list_for_each_entry_safe(q, n, &pending->list, list) {
497 int sig = q->info.si_signo;
498
499 if (likely(q->info.si_code != SI_TIMER)) {
500 sigaddset(&retain, sig);
501 } else {
502 sigdelset(&signal, sig);
503 list_del_init(&q->list);
504 __sigqueue_free(q);
505 }
506 }
507
508 sigorsets(&pending->signal, &signal, &retain);
509}
510
511void flush_itimer_signals(void)
512{
513 struct task_struct *tsk = current;
514 unsigned long flags;
515
516 spin_lock_irqsave(&tsk->sighand->siglock, flags);
517 __flush_itimer_signals(&tsk->pending);
518 __flush_itimer_signals(&tsk->signal->shared_pending);
519 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
520}
521#endif
522
523void ignore_signals(struct task_struct *t)
524{
525 int i;
526
527 for (i = 0; i < _NSIG; ++i)
528 t->sighand->action[i].sa.sa_handler = SIG_IGN;
529
530 flush_signals(t);
531}
532
533/*
534 * Flush all handlers for a task.
535 */
536
537void
538flush_signal_handlers(struct task_struct *t, int force_default)
539{
540 int i;
541 struct k_sigaction *ka = &t->sighand->action[0];
542 for (i = _NSIG ; i != 0 ; i--) {
543 if (force_default || ka->sa.sa_handler != SIG_IGN)
544 ka->sa.sa_handler = SIG_DFL;
545 ka->sa.sa_flags = 0;
546#ifdef __ARCH_HAS_SA_RESTORER
547 ka->sa.sa_restorer = NULL;
548#endif
549 sigemptyset(&ka->sa.sa_mask);
550 ka++;
551 }
552}
553
554bool unhandled_signal(struct task_struct *tsk, int sig)
555{
556 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
557 if (is_global_init(tsk))
558 return true;
559
560 if (handler != SIG_IGN && handler != SIG_DFL)
561 return false;
562
563 /* if ptraced, let the tracer determine */
564 return !tsk->ptrace;
565}
566
567static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
568 bool *resched_timer)
569{
570 struct sigqueue *q, *first = NULL;
571
572 /*
573 * Collect the siginfo appropriate to this signal. Check if
574 * there is another siginfo for the same signal.
575 */
576 list_for_each_entry(q, &list->list, list) {
577 if (q->info.si_signo == sig) {
578 if (first)
579 goto still_pending;
580 first = q;
581 }
582 }
583
584 sigdelset(&list->signal, sig);
585
586 if (first) {
587still_pending:
588 list_del_init(&first->list);
589 copy_siginfo(info, &first->info);
590
591 *resched_timer =
592 (first->flags & SIGQUEUE_PREALLOC) &&
593 (info->si_code == SI_TIMER) &&
594 (info->si_sys_private);
595
596 __sigqueue_free(first);
597 } else {
598 /*
599 * Ok, it wasn't in the queue. This must be
600 * a fast-pathed signal or we must have been
601 * out of queue space. So zero out the info.
602 */
603 clear_siginfo(info);
604 info->si_signo = sig;
605 info->si_errno = 0;
606 info->si_code = SI_USER;
607 info->si_pid = 0;
608 info->si_uid = 0;
609 }
610}
611
612static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
613 kernel_siginfo_t *info, bool *resched_timer)
614{
615 int sig = next_signal(pending, mask);
616
617 if (sig)
618 collect_signal(sig, pending, info, resched_timer);
619 return sig;
620}
621
622/*
623 * Dequeue a signal and return the element to the caller, which is
624 * expected to free it.
625 *
626 * All callers have to hold the siglock.
627 */
628int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
629{
630 bool resched_timer = false;
631 int signr;
632
633 /* We only dequeue private signals from ourselves, we don't let
634 * signalfd steal them
635 */
636 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
637 if (!signr) {
638 signr = __dequeue_signal(&tsk->signal->shared_pending,
639 mask, info, &resched_timer);
640#ifdef CONFIG_POSIX_TIMERS
641 /*
642 * itimer signal ?
643 *
644 * itimers are process shared and we restart periodic
645 * itimers in the signal delivery path to prevent DoS
646 * attacks in the high resolution timer case. This is
647 * compliant with the old way of self-restarting
648 * itimers, as the SIGALRM is a legacy signal and only
649 * queued once. Changing the restart behaviour to
650 * restart the timer in the signal dequeue path is
651 * reducing the timer noise on heavy loaded !highres
652 * systems too.
653 */
654 if (unlikely(signr == SIGALRM)) {
655 struct hrtimer *tmr = &tsk->signal->real_timer;
656
657 if (!hrtimer_is_queued(tmr) &&
658 tsk->signal->it_real_incr != 0) {
659 hrtimer_forward(tmr, tmr->base->get_time(),
660 tsk->signal->it_real_incr);
661 hrtimer_restart(tmr);
662 }
663 }
664#endif
665 }
666
667 recalc_sigpending();
668 if (!signr)
669 return 0;
670
671 if (unlikely(sig_kernel_stop(signr))) {
672 /*
673 * Set a marker that we have dequeued a stop signal. Our
674 * caller might release the siglock and then the pending
675 * stop signal it is about to process is no longer in the
676 * pending bitmasks, but must still be cleared by a SIGCONT
677 * (and overruled by a SIGKILL). So those cases clear this
678 * shared flag after we've set it. Note that this flag may
679 * remain set after the signal we return is ignored or
680 * handled. That doesn't matter because its only purpose
681 * is to alert stop-signal processing code when another
682 * processor has come along and cleared the flag.
683 */
684 current->jobctl |= JOBCTL_STOP_DEQUEUED;
685 }
686#ifdef CONFIG_POSIX_TIMERS
687 if (resched_timer) {
688 /*
689 * Release the siglock to ensure proper locking order
690 * of timer locks outside of siglocks. Note, we leave
691 * irqs disabled here, since the posix-timers code is
692 * about to disable them again anyway.
693 */
694 spin_unlock(&tsk->sighand->siglock);
695 posixtimer_rearm(info);
696 spin_lock(&tsk->sighand->siglock);
697
698 /* Don't expose the si_sys_private value to userspace */
699 info->si_sys_private = 0;
700 }
701#endif
702 return signr;
703}
704EXPORT_SYMBOL_GPL(dequeue_signal);
705
706static int dequeue_synchronous_signal(kernel_siginfo_t *info)
707{
708 struct task_struct *tsk = current;
709 struct sigpending *pending = &tsk->pending;
710 struct sigqueue *q, *sync = NULL;
711
712 /*
713 * Might a synchronous signal be in the queue?
714 */
715 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
716 return 0;
717
718 /*
719 * Return the first synchronous signal in the queue.
720 */
721 list_for_each_entry(q, &pending->list, list) {
722 /* Synchronous signals have a positive si_code */
723 if ((q->info.si_code > SI_USER) &&
724 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
725 sync = q;
726 goto next;
727 }
728 }
729 return 0;
730next:
731 /*
732 * Check if there is another siginfo for the same signal.
733 */
734 list_for_each_entry_continue(q, &pending->list, list) {
735 if (q->info.si_signo == sync->info.si_signo)
736 goto still_pending;
737 }
738
739 sigdelset(&pending->signal, sync->info.si_signo);
740 recalc_sigpending();
741still_pending:
742 list_del_init(&sync->list);
743 copy_siginfo(info, &sync->info);
744 __sigqueue_free(sync);
745 return info->si_signo;
746}
747
748/*
749 * Tell a process that it has a new active signal..
750 *
751 * NOTE! we rely on the previous spin_lock to
752 * lock interrupts for us! We can only be called with
753 * "siglock" held, and the local interrupt must
754 * have been disabled when that got acquired!
755 *
756 * No need to set need_resched since signal event passing
757 * goes through ->blocked
758 */
759void signal_wake_up_state(struct task_struct *t, unsigned int state)
760{
761 set_tsk_thread_flag(t, TIF_SIGPENDING);
762 /*
763 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
764 * case. We don't check t->state here because there is a race with it
765 * executing another processor and just now entering stopped state.
766 * By using wake_up_state, we ensure the process will wake up and
767 * handle its death signal.
768 */
769 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
770 kick_process(t);
771}
772
773/*
774 * Remove signals in mask from the pending set and queue.
775 * Returns 1 if any signals were found.
776 *
777 * All callers must be holding the siglock.
778 */
779static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
780{
781 struct sigqueue *q, *n;
782 sigset_t m;
783
784 sigandsets(&m, mask, &s->signal);
785 if (sigisemptyset(&m))
786 return;
787
788 sigandnsets(&s->signal, &s->signal, mask);
789 list_for_each_entry_safe(q, n, &s->list, list) {
790 if (sigismember(mask, q->info.si_signo)) {
791 list_del_init(&q->list);
792 __sigqueue_free(q);
793 }
794 }
795}
796
797static inline int is_si_special(const struct kernel_siginfo *info)
798{
799 return info <= SEND_SIG_PRIV;
800}
801
802static inline bool si_fromuser(const struct kernel_siginfo *info)
803{
804 return info == SEND_SIG_NOINFO ||
805 (!is_si_special(info) && SI_FROMUSER(info));
806}
807
808/*
809 * called with RCU read lock from check_kill_permission()
810 */
811static bool kill_ok_by_cred(struct task_struct *t)
812{
813 const struct cred *cred = current_cred();
814 const struct cred *tcred = __task_cred(t);
815
816 return uid_eq(cred->euid, tcred->suid) ||
817 uid_eq(cred->euid, tcred->uid) ||
818 uid_eq(cred->uid, tcred->suid) ||
819 uid_eq(cred->uid, tcred->uid) ||
820 ns_capable(tcred->user_ns, CAP_KILL);
821}
822
823/*
824 * Bad permissions for sending the signal
825 * - the caller must hold the RCU read lock
826 */
827static int check_kill_permission(int sig, struct kernel_siginfo *info,
828 struct task_struct *t)
829{
830 struct pid *sid;
831 int error;
832
833 if (!valid_signal(sig))
834 return -EINVAL;
835
836 if (!si_fromuser(info))
837 return 0;
838
839 error = audit_signal_info(sig, t); /* Let audit system see the signal */
840 if (error)
841 return error;
842
843 if (!same_thread_group(current, t) &&
844 !kill_ok_by_cred(t)) {
845 switch (sig) {
846 case SIGCONT:
847 sid = task_session(t);
848 /*
849 * We don't return the error if sid == NULL. The
850 * task was unhashed, the caller must notice this.
851 */
852 if (!sid || sid == task_session(current))
853 break;
854 fallthrough;
855 default:
856 return -EPERM;
857 }
858 }
859
860 return security_task_kill(t, info, sig, NULL);
861}
862
863/**
864 * ptrace_trap_notify - schedule trap to notify ptracer
865 * @t: tracee wanting to notify tracer
866 *
867 * This function schedules sticky ptrace trap which is cleared on the next
868 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
869 * ptracer.
870 *
871 * If @t is running, STOP trap will be taken. If trapped for STOP and
872 * ptracer is listening for events, tracee is woken up so that it can
873 * re-trap for the new event. If trapped otherwise, STOP trap will be
874 * eventually taken without returning to userland after the existing traps
875 * are finished by PTRACE_CONT.
876 *
877 * CONTEXT:
878 * Must be called with @task->sighand->siglock held.
879 */
880static void ptrace_trap_notify(struct task_struct *t)
881{
882 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
883 assert_spin_locked(&t->sighand->siglock);
884
885 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
886 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
887}
888
889/*
890 * Handle magic process-wide effects of stop/continue signals. Unlike
891 * the signal actions, these happen immediately at signal-generation
892 * time regardless of blocking, ignoring, or handling. This does the
893 * actual continuing for SIGCONT, but not the actual stopping for stop
894 * signals. The process stop is done as a signal action for SIG_DFL.
895 *
896 * Returns true if the signal should be actually delivered, otherwise
897 * it should be dropped.
898 */
899static bool prepare_signal(int sig, struct task_struct *p, bool force)
900{
901 struct signal_struct *signal = p->signal;
902 struct task_struct *t;
903 sigset_t flush;
904
905 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
906 if (!(signal->flags & SIGNAL_GROUP_EXIT))
907 return sig == SIGKILL;
908 /*
909 * The process is in the middle of dying, nothing to do.
910 */
911 } else if (sig_kernel_stop(sig)) {
912 /*
913 * This is a stop signal. Remove SIGCONT from all queues.
914 */
915 siginitset(&flush, sigmask(SIGCONT));
916 flush_sigqueue_mask(&flush, &signal->shared_pending);
917 for_each_thread(p, t)
918 flush_sigqueue_mask(&flush, &t->pending);
919 } else if (sig == SIGCONT) {
920 unsigned int why;
921 /*
922 * Remove all stop signals from all queues, wake all threads.
923 */
924 siginitset(&flush, SIG_KERNEL_STOP_MASK);
925 flush_sigqueue_mask(&flush, &signal->shared_pending);
926 for_each_thread(p, t) {
927 flush_sigqueue_mask(&flush, &t->pending);
928 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
929 if (likely(!(t->ptrace & PT_SEIZED)))
930 wake_up_state(t, __TASK_STOPPED);
931 else
932 ptrace_trap_notify(t);
933 }
934
935 /*
936 * Notify the parent with CLD_CONTINUED if we were stopped.
937 *
938 * If we were in the middle of a group stop, we pretend it
939 * was already finished, and then continued. Since SIGCHLD
940 * doesn't queue we report only CLD_STOPPED, as if the next
941 * CLD_CONTINUED was dropped.
942 */
943 why = 0;
944 if (signal->flags & SIGNAL_STOP_STOPPED)
945 why |= SIGNAL_CLD_CONTINUED;
946 else if (signal->group_stop_count)
947 why |= SIGNAL_CLD_STOPPED;
948
949 if (why) {
950 /*
951 * The first thread which returns from do_signal_stop()
952 * will take ->siglock, notice SIGNAL_CLD_MASK, and
953 * notify its parent. See get_signal().
954 */
955 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
956 signal->group_stop_count = 0;
957 signal->group_exit_code = 0;
958 }
959 }
960
961 return !sig_ignored(p, sig, force);
962}
963
964/*
965 * Test if P wants to take SIG. After we've checked all threads with this,
966 * it's equivalent to finding no threads not blocking SIG. Any threads not
967 * blocking SIG were ruled out because they are not running and already
968 * have pending signals. Such threads will dequeue from the shared queue
969 * as soon as they're available, so putting the signal on the shared queue
970 * will be equivalent to sending it to one such thread.
971 */
972static inline bool wants_signal(int sig, struct task_struct *p)
973{
974 if (sigismember(&p->blocked, sig))
975 return false;
976
977 if (p->flags & PF_EXITING)
978 return false;
979
980 if (sig == SIGKILL)
981 return true;
982
983 if (task_is_stopped_or_traced(p))
984 return false;
985
986 return task_curr(p) || !task_sigpending(p);
987}
988
989static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
990{
991 struct signal_struct *signal = p->signal;
992 struct task_struct *t;
993
994 /*
995 * Now find a thread we can wake up to take the signal off the queue.
996 *
997 * If the main thread wants the signal, it gets first crack.
998 * Probably the least surprising to the average bear.
999 */
1000 if (wants_signal(sig, p))
1001 t = p;
1002 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1003 /*
1004 * There is just one thread and it does not need to be woken.
1005 * It will dequeue unblocked signals before it runs again.
1006 */
1007 return;
1008 else {
1009 /*
1010 * Otherwise try to find a suitable thread.
1011 */
1012 t = signal->curr_target;
1013 while (!wants_signal(sig, t)) {
1014 t = next_thread(t);
1015 if (t == signal->curr_target)
1016 /*
1017 * No thread needs to be woken.
1018 * Any eligible threads will see
1019 * the signal in the queue soon.
1020 */
1021 return;
1022 }
1023 signal->curr_target = t;
1024 }
1025
1026 /*
1027 * Found a killable thread. If the signal will be fatal,
1028 * then start taking the whole group down immediately.
1029 */
1030 if (sig_fatal(p, sig) &&
1031 !(signal->flags & SIGNAL_GROUP_EXIT) &&
1032 !sigismember(&t->real_blocked, sig) &&
1033 (sig == SIGKILL || !p->ptrace)) {
1034 /*
1035 * This signal will be fatal to the whole group.
1036 */
1037 if (!sig_kernel_coredump(sig)) {
1038 /*
1039 * Start a group exit and wake everybody up.
1040 * This way we don't have other threads
1041 * running and doing things after a slower
1042 * thread has the fatal signal pending.
1043 */
1044 signal->flags = SIGNAL_GROUP_EXIT;
1045 signal->group_exit_code = sig;
1046 signal->group_stop_count = 0;
1047 t = p;
1048 do {
1049 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1050 sigaddset(&t->pending.signal, SIGKILL);
1051 signal_wake_up(t, 1);
1052 } while_each_thread(p, t);
1053 return;
1054 }
1055 }
1056
1057 /*
1058 * The signal is already in the shared-pending queue.
1059 * Tell the chosen thread to wake up and dequeue it.
1060 */
1061 signal_wake_up(t, sig == SIGKILL);
1062 return;
1063}
1064
1065static inline bool legacy_queue(struct sigpending *signals, int sig)
1066{
1067 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1068}
1069
1070static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1071 enum pid_type type, bool force)
1072{
1073 struct sigpending *pending;
1074 struct sigqueue *q;
1075 int override_rlimit;
1076 int ret = 0, result;
1077
1078 assert_spin_locked(&t->sighand->siglock);
1079
1080 result = TRACE_SIGNAL_IGNORED;
1081 if (!prepare_signal(sig, t, force))
1082 goto ret;
1083
1084 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1085 /*
1086 * Short-circuit ignored signals and support queuing
1087 * exactly one non-rt signal, so that we can get more
1088 * detailed information about the cause of the signal.
1089 */
1090 result = TRACE_SIGNAL_ALREADY_PENDING;
1091 if (legacy_queue(pending, sig))
1092 goto ret;
1093
1094 result = TRACE_SIGNAL_DELIVERED;
1095 /*
1096 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1097 */
1098 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1099 goto out_set;
1100
1101 /*
1102 * Real-time signals must be queued if sent by sigqueue, or
1103 * some other real-time mechanism. It is implementation
1104 * defined whether kill() does so. We attempt to do so, on
1105 * the principle of least surprise, but since kill is not
1106 * allowed to fail with EAGAIN when low on memory we just
1107 * make sure at least one signal gets delivered and don't
1108 * pass on the info struct.
1109 */
1110 if (sig < SIGRTMIN)
1111 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1112 else
1113 override_rlimit = 0;
1114
1115 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1116
1117 if (q) {
1118 list_add_tail(&q->list, &pending->list);
1119 switch ((unsigned long) info) {
1120 case (unsigned long) SEND_SIG_NOINFO:
1121 clear_siginfo(&q->info);
1122 q->info.si_signo = sig;
1123 q->info.si_errno = 0;
1124 q->info.si_code = SI_USER;
1125 q->info.si_pid = task_tgid_nr_ns(current,
1126 task_active_pid_ns(t));
1127 rcu_read_lock();
1128 q->info.si_uid =
1129 from_kuid_munged(task_cred_xxx(t, user_ns),
1130 current_uid());
1131 rcu_read_unlock();
1132 break;
1133 case (unsigned long) SEND_SIG_PRIV:
1134 clear_siginfo(&q->info);
1135 q->info.si_signo = sig;
1136 q->info.si_errno = 0;
1137 q->info.si_code = SI_KERNEL;
1138 q->info.si_pid = 0;
1139 q->info.si_uid = 0;
1140 break;
1141 default:
1142 copy_siginfo(&q->info, info);
1143 break;
1144 }
1145 } else if (!is_si_special(info) &&
1146 sig >= SIGRTMIN && info->si_code != SI_USER) {
1147 /*
1148 * Queue overflow, abort. We may abort if the
1149 * signal was rt and sent by user using something
1150 * other than kill().
1151 */
1152 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1153 ret = -EAGAIN;
1154 goto ret;
1155 } else {
1156 /*
1157 * This is a silent loss of information. We still
1158 * send the signal, but the *info bits are lost.
1159 */
1160 result = TRACE_SIGNAL_LOSE_INFO;
1161 }
1162
1163out_set:
1164 signalfd_notify(t, sig);
1165 sigaddset(&pending->signal, sig);
1166
1167 /* Let multiprocess signals appear after on-going forks */
1168 if (type > PIDTYPE_TGID) {
1169 struct multiprocess_signals *delayed;
1170 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1171 sigset_t *signal = &delayed->signal;
1172 /* Can't queue both a stop and a continue signal */
1173 if (sig == SIGCONT)
1174 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1175 else if (sig_kernel_stop(sig))
1176 sigdelset(signal, SIGCONT);
1177 sigaddset(signal, sig);
1178 }
1179 }
1180
1181 complete_signal(sig, t, type);
1182ret:
1183 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1184 return ret;
1185}
1186
1187static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1188{
1189 bool ret = false;
1190 switch (siginfo_layout(info->si_signo, info->si_code)) {
1191 case SIL_KILL:
1192 case SIL_CHLD:
1193 case SIL_RT:
1194 ret = true;
1195 break;
1196 case SIL_TIMER:
1197 case SIL_POLL:
1198 case SIL_FAULT:
1199 case SIL_FAULT_TRAPNO:
1200 case SIL_FAULT_MCEERR:
1201 case SIL_FAULT_BNDERR:
1202 case SIL_FAULT_PKUERR:
1203 case SIL_PERF_EVENT:
1204 case SIL_SYS:
1205 ret = false;
1206 break;
1207 }
1208 return ret;
1209}
1210
1211static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1212 enum pid_type type)
1213{
1214 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1215 bool force = false;
1216
1217 if (info == SEND_SIG_NOINFO) {
1218 /* Force if sent from an ancestor pid namespace */
1219 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1220 } else if (info == SEND_SIG_PRIV) {
1221 /* Don't ignore kernel generated signals */
1222 force = true;
1223 } else if (has_si_pid_and_uid(info)) {
1224 /* SIGKILL and SIGSTOP is special or has ids */
1225 struct user_namespace *t_user_ns;
1226
1227 rcu_read_lock();
1228 t_user_ns = task_cred_xxx(t, user_ns);
1229 if (current_user_ns() != t_user_ns) {
1230 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1231 info->si_uid = from_kuid_munged(t_user_ns, uid);
1232 }
1233 rcu_read_unlock();
1234
1235 /* A kernel generated signal? */
1236 force = (info->si_code == SI_KERNEL);
1237
1238 /* From an ancestor pid namespace? */
1239 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1240 info->si_pid = 0;
1241 force = true;
1242 }
1243 }
1244 return __send_signal(sig, info, t, type, force);
1245}
1246
1247static void print_fatal_signal(int signr)
1248{
1249 struct pt_regs *regs = signal_pt_regs();
1250 pr_info("potentially unexpected fatal signal %d.\n", signr);
1251
1252#if defined(__i386__) && !defined(__arch_um__)
1253 pr_info("code at %08lx: ", regs->ip);
1254 {
1255 int i;
1256 for (i = 0; i < 16; i++) {
1257 unsigned char insn;
1258
1259 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1260 break;
1261 pr_cont("%02x ", insn);
1262 }
1263 }
1264 pr_cont("\n");
1265#endif
1266 preempt_disable();
1267 show_regs(regs);
1268 preempt_enable();
1269}
1270
1271static int __init setup_print_fatal_signals(char *str)
1272{
1273 get_option (&str, &print_fatal_signals);
1274
1275 return 1;
1276}
1277
1278__setup("print-fatal-signals=", setup_print_fatal_signals);
1279
1280int
1281__group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1282{
1283 return send_signal(sig, info, p, PIDTYPE_TGID);
1284}
1285
1286int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1287 enum pid_type type)
1288{
1289 unsigned long flags;
1290 int ret = -ESRCH;
1291
1292 if (lock_task_sighand(p, &flags)) {
1293 ret = send_signal(sig, info, p, type);
1294 unlock_task_sighand(p, &flags);
1295 }
1296
1297 return ret;
1298}
1299
1300/*
1301 * Force a signal that the process can't ignore: if necessary
1302 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1303 *
1304 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1305 * since we do not want to have a signal handler that was blocked
1306 * be invoked when user space had explicitly blocked it.
1307 *
1308 * We don't want to have recursive SIGSEGV's etc, for example,
1309 * that is why we also clear SIGNAL_UNKILLABLE.
1310 */
1311static int
1312force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
1313{
1314 unsigned long int flags;
1315 int ret, blocked, ignored;
1316 struct k_sigaction *action;
1317 int sig = info->si_signo;
1318
1319 spin_lock_irqsave(&t->sighand->siglock, flags);
1320 action = &t->sighand->action[sig-1];
1321 ignored = action->sa.sa_handler == SIG_IGN;
1322 blocked = sigismember(&t->blocked, sig);
1323 if (blocked || ignored) {
1324 action->sa.sa_handler = SIG_DFL;
1325 if (blocked) {
1326 sigdelset(&t->blocked, sig);
1327 recalc_sigpending_and_wake(t);
1328 }
1329 }
1330 /*
1331 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1332 * debugging to leave init killable.
1333 */
1334 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1335 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1336 ret = send_signal(sig, info, t, PIDTYPE_PID);
1337 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1338
1339 return ret;
1340}
1341
1342int force_sig_info(struct kernel_siginfo *info)
1343{
1344 return force_sig_info_to_task(info, current);
1345}
1346
1347/*
1348 * Nuke all other threads in the group.
1349 */
1350int zap_other_threads(struct task_struct *p)
1351{
1352 struct task_struct *t = p;
1353 int count = 0;
1354
1355 p->signal->group_stop_count = 0;
1356
1357 while_each_thread(p, t) {
1358 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1359 count++;
1360
1361 /* Don't bother with already dead threads */
1362 if (t->exit_state)
1363 continue;
1364 sigaddset(&t->pending.signal, SIGKILL);
1365 signal_wake_up(t, 1);
1366 }
1367
1368 return count;
1369}
1370
1371struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1372 unsigned long *flags)
1373{
1374 struct sighand_struct *sighand;
1375
1376 rcu_read_lock();
1377 for (;;) {
1378 sighand = rcu_dereference(tsk->sighand);
1379 if (unlikely(sighand == NULL))
1380 break;
1381
1382 /*
1383 * This sighand can be already freed and even reused, but
1384 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1385 * initializes ->siglock: this slab can't go away, it has
1386 * the same object type, ->siglock can't be reinitialized.
1387 *
1388 * We need to ensure that tsk->sighand is still the same
1389 * after we take the lock, we can race with de_thread() or
1390 * __exit_signal(). In the latter case the next iteration
1391 * must see ->sighand == NULL.
1392 */
1393 spin_lock_irqsave(&sighand->siglock, *flags);
1394 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1395 break;
1396 spin_unlock_irqrestore(&sighand->siglock, *flags);
1397 }
1398 rcu_read_unlock();
1399
1400 return sighand;
1401}
1402
1403/*
1404 * send signal info to all the members of a group
1405 */
1406int group_send_sig_info(int sig, struct kernel_siginfo *info,
1407 struct task_struct *p, enum pid_type type)
1408{
1409 int ret;
1410
1411 rcu_read_lock();
1412 ret = check_kill_permission(sig, info, p);
1413 rcu_read_unlock();
1414
1415 if (!ret && sig)
1416 ret = do_send_sig_info(sig, info, p, type);
1417
1418 return ret;
1419}
1420
1421/*
1422 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1423 * control characters do (^C, ^Z etc)
1424 * - the caller must hold at least a readlock on tasklist_lock
1425 */
1426int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1427{
1428 struct task_struct *p = NULL;
1429 int retval, success;
1430
1431 success = 0;
1432 retval = -ESRCH;
1433 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1434 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1435 success |= !err;
1436 retval = err;
1437 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1438 return success ? 0 : retval;
1439}
1440
1441int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1442{
1443 int error = -ESRCH;
1444 struct task_struct *p;
1445
1446 for (;;) {
1447 rcu_read_lock();
1448 p = pid_task(pid, PIDTYPE_PID);
1449 if (p)
1450 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1451 rcu_read_unlock();
1452 if (likely(!p || error != -ESRCH))
1453 return error;
1454
1455 /*
1456 * The task was unhashed in between, try again. If it
1457 * is dead, pid_task() will return NULL, if we race with
1458 * de_thread() it will find the new leader.
1459 */
1460 }
1461}
1462
1463static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1464{
1465 int error;
1466 rcu_read_lock();
1467 error = kill_pid_info(sig, info, find_vpid(pid));
1468 rcu_read_unlock();
1469 return error;
1470}
1471
1472static inline bool kill_as_cred_perm(const struct cred *cred,
1473 struct task_struct *target)
1474{
1475 const struct cred *pcred = __task_cred(target);
1476
1477 return uid_eq(cred->euid, pcred->suid) ||
1478 uid_eq(cred->euid, pcred->uid) ||
1479 uid_eq(cred->uid, pcred->suid) ||
1480 uid_eq(cred->uid, pcred->uid);
1481}
1482
1483/*
1484 * The usb asyncio usage of siginfo is wrong. The glibc support
1485 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1486 * AKA after the generic fields:
1487 * kernel_pid_t si_pid;
1488 * kernel_uid32_t si_uid;
1489 * sigval_t si_value;
1490 *
1491 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1492 * after the generic fields is:
1493 * void __user *si_addr;
1494 *
1495 * This is a practical problem when there is a 64bit big endian kernel
1496 * and a 32bit userspace. As the 32bit address will encoded in the low
1497 * 32bits of the pointer. Those low 32bits will be stored at higher
1498 * address than appear in a 32 bit pointer. So userspace will not
1499 * see the address it was expecting for it's completions.
1500 *
1501 * There is nothing in the encoding that can allow
1502 * copy_siginfo_to_user32 to detect this confusion of formats, so
1503 * handle this by requiring the caller of kill_pid_usb_asyncio to
1504 * notice when this situration takes place and to store the 32bit
1505 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1506 * parameter.
1507 */
1508int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1509 struct pid *pid, const struct cred *cred)
1510{
1511 struct kernel_siginfo info;
1512 struct task_struct *p;
1513 unsigned long flags;
1514 int ret = -EINVAL;
1515
1516 if (!valid_signal(sig))
1517 return ret;
1518
1519 clear_siginfo(&info);
1520 info.si_signo = sig;
1521 info.si_errno = errno;
1522 info.si_code = SI_ASYNCIO;
1523 *((sigval_t *)&info.si_pid) = addr;
1524
1525 rcu_read_lock();
1526 p = pid_task(pid, PIDTYPE_PID);
1527 if (!p) {
1528 ret = -ESRCH;
1529 goto out_unlock;
1530 }
1531 if (!kill_as_cred_perm(cred, p)) {
1532 ret = -EPERM;
1533 goto out_unlock;
1534 }
1535 ret = security_task_kill(p, &info, sig, cred);
1536 if (ret)
1537 goto out_unlock;
1538
1539 if (sig) {
1540 if (lock_task_sighand(p, &flags)) {
1541 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1542 unlock_task_sighand(p, &flags);
1543 } else
1544 ret = -ESRCH;
1545 }
1546out_unlock:
1547 rcu_read_unlock();
1548 return ret;
1549}
1550EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1551
1552/*
1553 * kill_something_info() interprets pid in interesting ways just like kill(2).
1554 *
1555 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1556 * is probably wrong. Should make it like BSD or SYSV.
1557 */
1558
1559static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1560{
1561 int ret;
1562
1563 if (pid > 0)
1564 return kill_proc_info(sig, info, pid);
1565
1566 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1567 if (pid == INT_MIN)
1568 return -ESRCH;
1569
1570 read_lock(&tasklist_lock);
1571 if (pid != -1) {
1572 ret = __kill_pgrp_info(sig, info,
1573 pid ? find_vpid(-pid) : task_pgrp(current));
1574 } else {
1575 int retval = 0, count = 0;
1576 struct task_struct * p;
1577
1578 for_each_process(p) {
1579 if (task_pid_vnr(p) > 1 &&
1580 !same_thread_group(p, current)) {
1581 int err = group_send_sig_info(sig, info, p,
1582 PIDTYPE_MAX);
1583 ++count;
1584 if (err != -EPERM)
1585 retval = err;
1586 }
1587 }
1588 ret = count ? retval : -ESRCH;
1589 }
1590 read_unlock(&tasklist_lock);
1591
1592 return ret;
1593}
1594
1595/*
1596 * These are for backward compatibility with the rest of the kernel source.
1597 */
1598
1599int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1600{
1601 /*
1602 * Make sure legacy kernel users don't send in bad values
1603 * (normal paths check this in check_kill_permission).
1604 */
1605 if (!valid_signal(sig))
1606 return -EINVAL;
1607
1608 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1609}
1610EXPORT_SYMBOL(send_sig_info);
1611
1612#define __si_special(priv) \
1613 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1614
1615int
1616send_sig(int sig, struct task_struct *p, int priv)
1617{
1618 return send_sig_info(sig, __si_special(priv), p);
1619}
1620EXPORT_SYMBOL(send_sig);
1621
1622void force_sig(int sig)
1623{
1624 struct kernel_siginfo info;
1625
1626 clear_siginfo(&info);
1627 info.si_signo = sig;
1628 info.si_errno = 0;
1629 info.si_code = SI_KERNEL;
1630 info.si_pid = 0;
1631 info.si_uid = 0;
1632 force_sig_info(&info);
1633}
1634EXPORT_SYMBOL(force_sig);
1635
1636/*
1637 * When things go south during signal handling, we
1638 * will force a SIGSEGV. And if the signal that caused
1639 * the problem was already a SIGSEGV, we'll want to
1640 * make sure we don't even try to deliver the signal..
1641 */
1642void force_sigsegv(int sig)
1643{
1644 struct task_struct *p = current;
1645
1646 if (sig == SIGSEGV) {
1647 unsigned long flags;
1648 spin_lock_irqsave(&p->sighand->siglock, flags);
1649 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1650 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1651 }
1652 force_sig(SIGSEGV);
1653}
1654
1655int force_sig_fault_to_task(int sig, int code, void __user *addr
1656 ___ARCH_SI_TRAPNO(int trapno)
1657 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1658 , struct task_struct *t)
1659{
1660 struct kernel_siginfo info;
1661
1662 clear_siginfo(&info);
1663 info.si_signo = sig;
1664 info.si_errno = 0;
1665 info.si_code = code;
1666 info.si_addr = addr;
1667#ifdef __ARCH_SI_TRAPNO
1668 info.si_trapno = trapno;
1669#endif
1670#ifdef __ia64__
1671 info.si_imm = imm;
1672 info.si_flags = flags;
1673 info.si_isr = isr;
1674#endif
1675 return force_sig_info_to_task(&info, t);
1676}
1677
1678int force_sig_fault(int sig, int code, void __user *addr
1679 ___ARCH_SI_TRAPNO(int trapno)
1680 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1681{
1682 return force_sig_fault_to_task(sig, code, addr
1683 ___ARCH_SI_TRAPNO(trapno)
1684 ___ARCH_SI_IA64(imm, flags, isr), current);
1685}
1686
1687int send_sig_fault(int sig, int code, void __user *addr
1688 ___ARCH_SI_TRAPNO(int trapno)
1689 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1690 , struct task_struct *t)
1691{
1692 struct kernel_siginfo info;
1693
1694 clear_siginfo(&info);
1695 info.si_signo = sig;
1696 info.si_errno = 0;
1697 info.si_code = code;
1698 info.si_addr = addr;
1699#ifdef __ARCH_SI_TRAPNO
1700 info.si_trapno = trapno;
1701#endif
1702#ifdef __ia64__
1703 info.si_imm = imm;
1704 info.si_flags = flags;
1705 info.si_isr = isr;
1706#endif
1707 return send_sig_info(info.si_signo, &info, t);
1708}
1709
1710int force_sig_mceerr(int code, void __user *addr, short lsb)
1711{
1712 struct kernel_siginfo info;
1713
1714 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1715 clear_siginfo(&info);
1716 info.si_signo = SIGBUS;
1717 info.si_errno = 0;
1718 info.si_code = code;
1719 info.si_addr = addr;
1720 info.si_addr_lsb = lsb;
1721 return force_sig_info(&info);
1722}
1723
1724int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1725{
1726 struct kernel_siginfo info;
1727
1728 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1729 clear_siginfo(&info);
1730 info.si_signo = SIGBUS;
1731 info.si_errno = 0;
1732 info.si_code = code;
1733 info.si_addr = addr;
1734 info.si_addr_lsb = lsb;
1735 return send_sig_info(info.si_signo, &info, t);
1736}
1737EXPORT_SYMBOL(send_sig_mceerr);
1738
1739int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1740{
1741 struct kernel_siginfo info;
1742
1743 clear_siginfo(&info);
1744 info.si_signo = SIGSEGV;
1745 info.si_errno = 0;
1746 info.si_code = SEGV_BNDERR;
1747 info.si_addr = addr;
1748 info.si_lower = lower;
1749 info.si_upper = upper;
1750 return force_sig_info(&info);
1751}
1752
1753#ifdef SEGV_PKUERR
1754int force_sig_pkuerr(void __user *addr, u32 pkey)
1755{
1756 struct kernel_siginfo info;
1757
1758 clear_siginfo(&info);
1759 info.si_signo = SIGSEGV;
1760 info.si_errno = 0;
1761 info.si_code = SEGV_PKUERR;
1762 info.si_addr = addr;
1763 info.si_pkey = pkey;
1764 return force_sig_info(&info);
1765}
1766#endif
1767
1768int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
1769{
1770 struct kernel_siginfo info;
1771
1772 clear_siginfo(&info);
1773 info.si_signo = SIGTRAP;
1774 info.si_errno = 0;
1775 info.si_code = TRAP_PERF;
1776 info.si_addr = addr;
1777 info.si_perf_data = sig_data;
1778 info.si_perf_type = type;
1779
1780 return force_sig_info(&info);
1781}
1782
1783/* For the crazy architectures that include trap information in
1784 * the errno field, instead of an actual errno value.
1785 */
1786int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1787{
1788 struct kernel_siginfo info;
1789
1790 clear_siginfo(&info);
1791 info.si_signo = SIGTRAP;
1792 info.si_errno = errno;
1793 info.si_code = TRAP_HWBKPT;
1794 info.si_addr = addr;
1795 return force_sig_info(&info);
1796}
1797
1798int kill_pgrp(struct pid *pid, int sig, int priv)
1799{
1800 int ret;
1801
1802 read_lock(&tasklist_lock);
1803 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1804 read_unlock(&tasklist_lock);
1805
1806 return ret;
1807}
1808EXPORT_SYMBOL(kill_pgrp);
1809
1810int kill_pid(struct pid *pid, int sig, int priv)
1811{
1812 return kill_pid_info(sig, __si_special(priv), pid);
1813}
1814EXPORT_SYMBOL(kill_pid);
1815
1816/*
1817 * These functions support sending signals using preallocated sigqueue
1818 * structures. This is needed "because realtime applications cannot
1819 * afford to lose notifications of asynchronous events, like timer
1820 * expirations or I/O completions". In the case of POSIX Timers
1821 * we allocate the sigqueue structure from the timer_create. If this
1822 * allocation fails we are able to report the failure to the application
1823 * with an EAGAIN error.
1824 */
1825struct sigqueue *sigqueue_alloc(void)
1826{
1827 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1828}
1829
1830void sigqueue_free(struct sigqueue *q)
1831{
1832 unsigned long flags;
1833 spinlock_t *lock = ¤t->sighand->siglock;
1834
1835 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1836 /*
1837 * We must hold ->siglock while testing q->list
1838 * to serialize with collect_signal() or with
1839 * __exit_signal()->flush_sigqueue().
1840 */
1841 spin_lock_irqsave(lock, flags);
1842 q->flags &= ~SIGQUEUE_PREALLOC;
1843 /*
1844 * If it is queued it will be freed when dequeued,
1845 * like the "regular" sigqueue.
1846 */
1847 if (!list_empty(&q->list))
1848 q = NULL;
1849 spin_unlock_irqrestore(lock, flags);
1850
1851 if (q)
1852 __sigqueue_free(q);
1853}
1854
1855int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1856{
1857 int sig = q->info.si_signo;
1858 struct sigpending *pending;
1859 struct task_struct *t;
1860 unsigned long flags;
1861 int ret, result;
1862
1863 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1864
1865 ret = -1;
1866 rcu_read_lock();
1867 t = pid_task(pid, type);
1868 if (!t || !likely(lock_task_sighand(t, &flags)))
1869 goto ret;
1870
1871 ret = 1; /* the signal is ignored */
1872 result = TRACE_SIGNAL_IGNORED;
1873 if (!prepare_signal(sig, t, false))
1874 goto out;
1875
1876 ret = 0;
1877 if (unlikely(!list_empty(&q->list))) {
1878 /*
1879 * If an SI_TIMER entry is already queue just increment
1880 * the overrun count.
1881 */
1882 BUG_ON(q->info.si_code != SI_TIMER);
1883 q->info.si_overrun++;
1884 result = TRACE_SIGNAL_ALREADY_PENDING;
1885 goto out;
1886 }
1887 q->info.si_overrun = 0;
1888
1889 signalfd_notify(t, sig);
1890 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1891 list_add_tail(&q->list, &pending->list);
1892 sigaddset(&pending->signal, sig);
1893 complete_signal(sig, t, type);
1894 result = TRACE_SIGNAL_DELIVERED;
1895out:
1896 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1897 unlock_task_sighand(t, &flags);
1898ret:
1899 rcu_read_unlock();
1900 return ret;
1901}
1902
1903static void do_notify_pidfd(struct task_struct *task)
1904{
1905 struct pid *pid;
1906
1907 WARN_ON(task->exit_state == 0);
1908 pid = task_pid(task);
1909 wake_up_all(&pid->wait_pidfd);
1910}
1911
1912/*
1913 * Let a parent know about the death of a child.
1914 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1915 *
1916 * Returns true if our parent ignored us and so we've switched to
1917 * self-reaping.
1918 */
1919bool do_notify_parent(struct task_struct *tsk, int sig)
1920{
1921 struct kernel_siginfo info;
1922 unsigned long flags;
1923 struct sighand_struct *psig;
1924 bool autoreap = false;
1925 u64 utime, stime;
1926
1927 BUG_ON(sig == -1);
1928
1929 /* do_notify_parent_cldstop should have been called instead. */
1930 BUG_ON(task_is_stopped_or_traced(tsk));
1931
1932 BUG_ON(!tsk->ptrace &&
1933 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1934
1935 /* Wake up all pidfd waiters */
1936 do_notify_pidfd(tsk);
1937
1938 if (sig != SIGCHLD) {
1939 /*
1940 * This is only possible if parent == real_parent.
1941 * Check if it has changed security domain.
1942 */
1943 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
1944 sig = SIGCHLD;
1945 }
1946
1947 clear_siginfo(&info);
1948 info.si_signo = sig;
1949 info.si_errno = 0;
1950 /*
1951 * We are under tasklist_lock here so our parent is tied to
1952 * us and cannot change.
1953 *
1954 * task_active_pid_ns will always return the same pid namespace
1955 * until a task passes through release_task.
1956 *
1957 * write_lock() currently calls preempt_disable() which is the
1958 * same as rcu_read_lock(), but according to Oleg, this is not
1959 * correct to rely on this
1960 */
1961 rcu_read_lock();
1962 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1963 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1964 task_uid(tsk));
1965 rcu_read_unlock();
1966
1967 task_cputime(tsk, &utime, &stime);
1968 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1969 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1970
1971 info.si_status = tsk->exit_code & 0x7f;
1972 if (tsk->exit_code & 0x80)
1973 info.si_code = CLD_DUMPED;
1974 else if (tsk->exit_code & 0x7f)
1975 info.si_code = CLD_KILLED;
1976 else {
1977 info.si_code = CLD_EXITED;
1978 info.si_status = tsk->exit_code >> 8;
1979 }
1980
1981 psig = tsk->parent->sighand;
1982 spin_lock_irqsave(&psig->siglock, flags);
1983 if (!tsk->ptrace && sig == SIGCHLD &&
1984 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1985 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1986 /*
1987 * We are exiting and our parent doesn't care. POSIX.1
1988 * defines special semantics for setting SIGCHLD to SIG_IGN
1989 * or setting the SA_NOCLDWAIT flag: we should be reaped
1990 * automatically and not left for our parent's wait4 call.
1991 * Rather than having the parent do it as a magic kind of
1992 * signal handler, we just set this to tell do_exit that we
1993 * can be cleaned up without becoming a zombie. Note that
1994 * we still call __wake_up_parent in this case, because a
1995 * blocked sys_wait4 might now return -ECHILD.
1996 *
1997 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1998 * is implementation-defined: we do (if you don't want
1999 * it, just use SIG_IGN instead).
2000 */
2001 autoreap = true;
2002 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2003 sig = 0;
2004 }
2005 /*
2006 * Send with __send_signal as si_pid and si_uid are in the
2007 * parent's namespaces.
2008 */
2009 if (valid_signal(sig) && sig)
2010 __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2011 __wake_up_parent(tsk, tsk->parent);
2012 spin_unlock_irqrestore(&psig->siglock, flags);
2013
2014 return autoreap;
2015}
2016
2017/**
2018 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2019 * @tsk: task reporting the state change
2020 * @for_ptracer: the notification is for ptracer
2021 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2022 *
2023 * Notify @tsk's parent that the stopped/continued state has changed. If
2024 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2025 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2026 *
2027 * CONTEXT:
2028 * Must be called with tasklist_lock at least read locked.
2029 */
2030static void do_notify_parent_cldstop(struct task_struct *tsk,
2031 bool for_ptracer, int why)
2032{
2033 struct kernel_siginfo info;
2034 unsigned long flags;
2035 struct task_struct *parent;
2036 struct sighand_struct *sighand;
2037 u64 utime, stime;
2038
2039 if (for_ptracer) {
2040 parent = tsk->parent;
2041 } else {
2042 tsk = tsk->group_leader;
2043 parent = tsk->real_parent;
2044 }
2045
2046 clear_siginfo(&info);
2047 info.si_signo = SIGCHLD;
2048 info.si_errno = 0;
2049 /*
2050 * see comment in do_notify_parent() about the following 4 lines
2051 */
2052 rcu_read_lock();
2053 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2054 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2055 rcu_read_unlock();
2056
2057 task_cputime(tsk, &utime, &stime);
2058 info.si_utime = nsec_to_clock_t(utime);
2059 info.si_stime = nsec_to_clock_t(stime);
2060
2061 info.si_code = why;
2062 switch (why) {
2063 case CLD_CONTINUED:
2064 info.si_status = SIGCONT;
2065 break;
2066 case CLD_STOPPED:
2067 info.si_status = tsk->signal->group_exit_code & 0x7f;
2068 break;
2069 case CLD_TRAPPED:
2070 info.si_status = tsk->exit_code & 0x7f;
2071 break;
2072 default:
2073 BUG();
2074 }
2075
2076 sighand = parent->sighand;
2077 spin_lock_irqsave(&sighand->siglock, flags);
2078 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2079 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2080 __group_send_sig_info(SIGCHLD, &info, parent);
2081 /*
2082 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2083 */
2084 __wake_up_parent(tsk, parent);
2085 spin_unlock_irqrestore(&sighand->siglock, flags);
2086}
2087
2088static inline bool may_ptrace_stop(void)
2089{
2090 if (!likely(current->ptrace))
2091 return false;
2092 /*
2093 * Are we in the middle of do_coredump?
2094 * If so and our tracer is also part of the coredump stopping
2095 * is a deadlock situation, and pointless because our tracer
2096 * is dead so don't allow us to stop.
2097 * If SIGKILL was already sent before the caller unlocked
2098 * ->siglock we must see ->core_state != NULL. Otherwise it
2099 * is safe to enter schedule().
2100 *
2101 * This is almost outdated, a task with the pending SIGKILL can't
2102 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
2103 * after SIGKILL was already dequeued.
2104 */
2105 if (unlikely(current->mm->core_state) &&
2106 unlikely(current->mm == current->parent->mm))
2107 return false;
2108
2109 return true;
2110}
2111
2112/*
2113 * Return non-zero if there is a SIGKILL that should be waking us up.
2114 * Called with the siglock held.
2115 */
2116static bool sigkill_pending(struct task_struct *tsk)
2117{
2118 return sigismember(&tsk->pending.signal, SIGKILL) ||
2119 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
2120}
2121
2122/*
2123 * This must be called with current->sighand->siglock held.
2124 *
2125 * This should be the path for all ptrace stops.
2126 * We always set current->last_siginfo while stopped here.
2127 * That makes it a way to test a stopped process for
2128 * being ptrace-stopped vs being job-control-stopped.
2129 *
2130 * If we actually decide not to stop at all because the tracer
2131 * is gone, we keep current->exit_code unless clear_code.
2132 */
2133static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
2134 __releases(¤t->sighand->siglock)
2135 __acquires(¤t->sighand->siglock)
2136{
2137 bool gstop_done = false;
2138
2139 if (arch_ptrace_stop_needed(exit_code, info)) {
2140 /*
2141 * The arch code has something special to do before a
2142 * ptrace stop. This is allowed to block, e.g. for faults
2143 * on user stack pages. We can't keep the siglock while
2144 * calling arch_ptrace_stop, so we must release it now.
2145 * To preserve proper semantics, we must do this before
2146 * any signal bookkeeping like checking group_stop_count.
2147 * Meanwhile, a SIGKILL could come in before we retake the
2148 * siglock. That must prevent us from sleeping in TASK_TRACED.
2149 * So after regaining the lock, we must check for SIGKILL.
2150 */
2151 spin_unlock_irq(¤t->sighand->siglock);
2152 arch_ptrace_stop(exit_code, info);
2153 spin_lock_irq(¤t->sighand->siglock);
2154 if (sigkill_pending(current))
2155 return;
2156 }
2157
2158 set_special_state(TASK_TRACED);
2159
2160 /*
2161 * We're committing to trapping. TRACED should be visible before
2162 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2163 * Also, transition to TRACED and updates to ->jobctl should be
2164 * atomic with respect to siglock and should be done after the arch
2165 * hook as siglock is released and regrabbed across it.
2166 *
2167 * TRACER TRACEE
2168 *
2169 * ptrace_attach()
2170 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2171 * do_wait()
2172 * set_current_state() smp_wmb();
2173 * ptrace_do_wait()
2174 * wait_task_stopped()
2175 * task_stopped_code()
2176 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2177 */
2178 smp_wmb();
2179
2180 current->last_siginfo = info;
2181 current->exit_code = exit_code;
2182
2183 /*
2184 * If @why is CLD_STOPPED, we're trapping to participate in a group
2185 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2186 * across siglock relocks since INTERRUPT was scheduled, PENDING
2187 * could be clear now. We act as if SIGCONT is received after
2188 * TASK_TRACED is entered - ignore it.
2189 */
2190 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2191 gstop_done = task_participate_group_stop(current);
2192
2193 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2194 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2195 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2196 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2197
2198 /* entering a trap, clear TRAPPING */
2199 task_clear_jobctl_trapping(current);
2200
2201 spin_unlock_irq(¤t->sighand->siglock);
2202 read_lock(&tasklist_lock);
2203 if (may_ptrace_stop()) {
2204 /*
2205 * Notify parents of the stop.
2206 *
2207 * While ptraced, there are two parents - the ptracer and
2208 * the real_parent of the group_leader. The ptracer should
2209 * know about every stop while the real parent is only
2210 * interested in the completion of group stop. The states
2211 * for the two don't interact with each other. Notify
2212 * separately unless they're gonna be duplicates.
2213 */
2214 do_notify_parent_cldstop(current, true, why);
2215 if (gstop_done && ptrace_reparented(current))
2216 do_notify_parent_cldstop(current, false, why);
2217
2218 /*
2219 * Don't want to allow preemption here, because
2220 * sys_ptrace() needs this task to be inactive.
2221 *
2222 * XXX: implement read_unlock_no_resched().
2223 */
2224 preempt_disable();
2225 read_unlock(&tasklist_lock);
2226 cgroup_enter_frozen();
2227 preempt_enable_no_resched();
2228 freezable_schedule();
2229 cgroup_leave_frozen(true);
2230 } else {
2231 /*
2232 * By the time we got the lock, our tracer went away.
2233 * Don't drop the lock yet, another tracer may come.
2234 *
2235 * If @gstop_done, the ptracer went away between group stop
2236 * completion and here. During detach, it would have set
2237 * JOBCTL_STOP_PENDING on us and we'll re-enter
2238 * TASK_STOPPED in do_signal_stop() on return, so notifying
2239 * the real parent of the group stop completion is enough.
2240 */
2241 if (gstop_done)
2242 do_notify_parent_cldstop(current, false, why);
2243
2244 /* tasklist protects us from ptrace_freeze_traced() */
2245 __set_current_state(TASK_RUNNING);
2246 if (clear_code)
2247 current->exit_code = 0;
2248 read_unlock(&tasklist_lock);
2249 }
2250
2251 /*
2252 * We are back. Now reacquire the siglock before touching
2253 * last_siginfo, so that we are sure to have synchronized with
2254 * any signal-sending on another CPU that wants to examine it.
2255 */
2256 spin_lock_irq(¤t->sighand->siglock);
2257 current->last_siginfo = NULL;
2258
2259 /* LISTENING can be set only during STOP traps, clear it */
2260 current->jobctl &= ~JOBCTL_LISTENING;
2261
2262 /*
2263 * Queued signals ignored us while we were stopped for tracing.
2264 * So check for any that we should take before resuming user mode.
2265 * This sets TIF_SIGPENDING, but never clears it.
2266 */
2267 recalc_sigpending_tsk(current);
2268}
2269
2270static void ptrace_do_notify(int signr, int exit_code, int why)
2271{
2272 kernel_siginfo_t info;
2273
2274 clear_siginfo(&info);
2275 info.si_signo = signr;
2276 info.si_code = exit_code;
2277 info.si_pid = task_pid_vnr(current);
2278 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2279
2280 /* Let the debugger run. */
2281 ptrace_stop(exit_code, why, 1, &info);
2282}
2283
2284void ptrace_notify(int exit_code)
2285{
2286 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2287 if (unlikely(current->task_works))
2288 task_work_run();
2289
2290 spin_lock_irq(¤t->sighand->siglock);
2291 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2292 spin_unlock_irq(¤t->sighand->siglock);
2293}
2294
2295/**
2296 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2297 * @signr: signr causing group stop if initiating
2298 *
2299 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2300 * and participate in it. If already set, participate in the existing
2301 * group stop. If participated in a group stop (and thus slept), %true is
2302 * returned with siglock released.
2303 *
2304 * If ptraced, this function doesn't handle stop itself. Instead,
2305 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2306 * untouched. The caller must ensure that INTERRUPT trap handling takes
2307 * places afterwards.
2308 *
2309 * CONTEXT:
2310 * Must be called with @current->sighand->siglock held, which is released
2311 * on %true return.
2312 *
2313 * RETURNS:
2314 * %false if group stop is already cancelled or ptrace trap is scheduled.
2315 * %true if participated in group stop.
2316 */
2317static bool do_signal_stop(int signr)
2318 __releases(¤t->sighand->siglock)
2319{
2320 struct signal_struct *sig = current->signal;
2321
2322 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2323 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2324 struct task_struct *t;
2325
2326 /* signr will be recorded in task->jobctl for retries */
2327 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2328
2329 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2330 unlikely(signal_group_exit(sig)))
2331 return false;
2332 /*
2333 * There is no group stop already in progress. We must
2334 * initiate one now.
2335 *
2336 * While ptraced, a task may be resumed while group stop is
2337 * still in effect and then receive a stop signal and
2338 * initiate another group stop. This deviates from the
2339 * usual behavior as two consecutive stop signals can't
2340 * cause two group stops when !ptraced. That is why we
2341 * also check !task_is_stopped(t) below.
2342 *
2343 * The condition can be distinguished by testing whether
2344 * SIGNAL_STOP_STOPPED is already set. Don't generate
2345 * group_exit_code in such case.
2346 *
2347 * This is not necessary for SIGNAL_STOP_CONTINUED because
2348 * an intervening stop signal is required to cause two
2349 * continued events regardless of ptrace.
2350 */
2351 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2352 sig->group_exit_code = signr;
2353
2354 sig->group_stop_count = 0;
2355
2356 if (task_set_jobctl_pending(current, signr | gstop))
2357 sig->group_stop_count++;
2358
2359 t = current;
2360 while_each_thread(current, t) {
2361 /*
2362 * Setting state to TASK_STOPPED for a group
2363 * stop is always done with the siglock held,
2364 * so this check has no races.
2365 */
2366 if (!task_is_stopped(t) &&
2367 task_set_jobctl_pending(t, signr | gstop)) {
2368 sig->group_stop_count++;
2369 if (likely(!(t->ptrace & PT_SEIZED)))
2370 signal_wake_up(t, 0);
2371 else
2372 ptrace_trap_notify(t);
2373 }
2374 }
2375 }
2376
2377 if (likely(!current->ptrace)) {
2378 int notify = 0;
2379
2380 /*
2381 * If there are no other threads in the group, or if there
2382 * is a group stop in progress and we are the last to stop,
2383 * report to the parent.
2384 */
2385 if (task_participate_group_stop(current))
2386 notify = CLD_STOPPED;
2387
2388 set_special_state(TASK_STOPPED);
2389 spin_unlock_irq(¤t->sighand->siglock);
2390
2391 /*
2392 * Notify the parent of the group stop completion. Because
2393 * we're not holding either the siglock or tasklist_lock
2394 * here, ptracer may attach inbetween; however, this is for
2395 * group stop and should always be delivered to the real
2396 * parent of the group leader. The new ptracer will get
2397 * its notification when this task transitions into
2398 * TASK_TRACED.
2399 */
2400 if (notify) {
2401 read_lock(&tasklist_lock);
2402 do_notify_parent_cldstop(current, false, notify);
2403 read_unlock(&tasklist_lock);
2404 }
2405
2406 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2407 cgroup_enter_frozen();
2408 freezable_schedule();
2409 return true;
2410 } else {
2411 /*
2412 * While ptraced, group stop is handled by STOP trap.
2413 * Schedule it and let the caller deal with it.
2414 */
2415 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2416 return false;
2417 }
2418}
2419
2420/**
2421 * do_jobctl_trap - take care of ptrace jobctl traps
2422 *
2423 * When PT_SEIZED, it's used for both group stop and explicit
2424 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2425 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2426 * the stop signal; otherwise, %SIGTRAP.
2427 *
2428 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2429 * number as exit_code and no siginfo.
2430 *
2431 * CONTEXT:
2432 * Must be called with @current->sighand->siglock held, which may be
2433 * released and re-acquired before returning with intervening sleep.
2434 */
2435static void do_jobctl_trap(void)
2436{
2437 struct signal_struct *signal = current->signal;
2438 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2439
2440 if (current->ptrace & PT_SEIZED) {
2441 if (!signal->group_stop_count &&
2442 !(signal->flags & SIGNAL_STOP_STOPPED))
2443 signr = SIGTRAP;
2444 WARN_ON_ONCE(!signr);
2445 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2446 CLD_STOPPED);
2447 } else {
2448 WARN_ON_ONCE(!signr);
2449 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2450 current->exit_code = 0;
2451 }
2452}
2453
2454/**
2455 * do_freezer_trap - handle the freezer jobctl trap
2456 *
2457 * Puts the task into frozen state, if only the task is not about to quit.
2458 * In this case it drops JOBCTL_TRAP_FREEZE.
2459 *
2460 * CONTEXT:
2461 * Must be called with @current->sighand->siglock held,
2462 * which is always released before returning.
2463 */
2464static void do_freezer_trap(void)
2465 __releases(¤t->sighand->siglock)
2466{
2467 /*
2468 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2469 * let's make another loop to give it a chance to be handled.
2470 * In any case, we'll return back.
2471 */
2472 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2473 JOBCTL_TRAP_FREEZE) {
2474 spin_unlock_irq(¤t->sighand->siglock);
2475 return;
2476 }
2477
2478 /*
2479 * Now we're sure that there is no pending fatal signal and no
2480 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2481 * immediately (if there is a non-fatal signal pending), and
2482 * put the task into sleep.
2483 */
2484 __set_current_state(TASK_INTERRUPTIBLE);
2485 clear_thread_flag(TIF_SIGPENDING);
2486 spin_unlock_irq(¤t->sighand->siglock);
2487 cgroup_enter_frozen();
2488 freezable_schedule();
2489}
2490
2491static int ptrace_signal(int signr, kernel_siginfo_t *info)
2492{
2493 /*
2494 * We do not check sig_kernel_stop(signr) but set this marker
2495 * unconditionally because we do not know whether debugger will
2496 * change signr. This flag has no meaning unless we are going
2497 * to stop after return from ptrace_stop(). In this case it will
2498 * be checked in do_signal_stop(), we should only stop if it was
2499 * not cleared by SIGCONT while we were sleeping. See also the
2500 * comment in dequeue_signal().
2501 */
2502 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2503 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2504
2505 /* We're back. Did the debugger cancel the sig? */
2506 signr = current->exit_code;
2507 if (signr == 0)
2508 return signr;
2509
2510 current->exit_code = 0;
2511
2512 /*
2513 * Update the siginfo structure if the signal has
2514 * changed. If the debugger wanted something
2515 * specific in the siginfo structure then it should
2516 * have updated *info via PTRACE_SETSIGINFO.
2517 */
2518 if (signr != info->si_signo) {
2519 clear_siginfo(info);
2520 info->si_signo = signr;
2521 info->si_errno = 0;
2522 info->si_code = SI_USER;
2523 rcu_read_lock();
2524 info->si_pid = task_pid_vnr(current->parent);
2525 info->si_uid = from_kuid_munged(current_user_ns(),
2526 task_uid(current->parent));
2527 rcu_read_unlock();
2528 }
2529
2530 /* If the (new) signal is now blocked, requeue it. */
2531 if (sigismember(¤t->blocked, signr)) {
2532 send_signal(signr, info, current, PIDTYPE_PID);
2533 signr = 0;
2534 }
2535
2536 return signr;
2537}
2538
2539static void hide_si_addr_tag_bits(struct ksignal *ksig)
2540{
2541 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2542 case SIL_FAULT:
2543 case SIL_FAULT_TRAPNO:
2544 case SIL_FAULT_MCEERR:
2545 case SIL_FAULT_BNDERR:
2546 case SIL_FAULT_PKUERR:
2547 case SIL_PERF_EVENT:
2548 ksig->info.si_addr = arch_untagged_si_addr(
2549 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2550 break;
2551 case SIL_KILL:
2552 case SIL_TIMER:
2553 case SIL_POLL:
2554 case SIL_CHLD:
2555 case SIL_RT:
2556 case SIL_SYS:
2557 break;
2558 }
2559}
2560
2561bool get_signal(struct ksignal *ksig)
2562{
2563 struct sighand_struct *sighand = current->sighand;
2564 struct signal_struct *signal = current->signal;
2565 int signr;
2566
2567 if (unlikely(current->task_works))
2568 task_work_run();
2569
2570 /*
2571 * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so
2572 * that the arch handlers don't all have to do it. If we get here
2573 * without TIF_SIGPENDING, just exit after running signal work.
2574 */
2575 if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
2576 if (test_thread_flag(TIF_NOTIFY_SIGNAL))
2577 tracehook_notify_signal();
2578 if (!task_sigpending(current))
2579 return false;
2580 }
2581
2582 if (unlikely(uprobe_deny_signal()))
2583 return false;
2584
2585 /*
2586 * Do this once, we can't return to user-mode if freezing() == T.
2587 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2588 * thus do not need another check after return.
2589 */
2590 try_to_freeze();
2591
2592relock:
2593 spin_lock_irq(&sighand->siglock);
2594
2595 /*
2596 * Every stopped thread goes here after wakeup. Check to see if
2597 * we should notify the parent, prepare_signal(SIGCONT) encodes
2598 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2599 */
2600 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2601 int why;
2602
2603 if (signal->flags & SIGNAL_CLD_CONTINUED)
2604 why = CLD_CONTINUED;
2605 else
2606 why = CLD_STOPPED;
2607
2608 signal->flags &= ~SIGNAL_CLD_MASK;
2609
2610 spin_unlock_irq(&sighand->siglock);
2611
2612 /*
2613 * Notify the parent that we're continuing. This event is
2614 * always per-process and doesn't make whole lot of sense
2615 * for ptracers, who shouldn't consume the state via
2616 * wait(2) either, but, for backward compatibility, notify
2617 * the ptracer of the group leader too unless it's gonna be
2618 * a duplicate.
2619 */
2620 read_lock(&tasklist_lock);
2621 do_notify_parent_cldstop(current, false, why);
2622
2623 if (ptrace_reparented(current->group_leader))
2624 do_notify_parent_cldstop(current->group_leader,
2625 true, why);
2626 read_unlock(&tasklist_lock);
2627
2628 goto relock;
2629 }
2630
2631 /* Has this task already been marked for death? */
2632 if (signal_group_exit(signal)) {
2633 ksig->info.si_signo = signr = SIGKILL;
2634 sigdelset(¤t->pending.signal, SIGKILL);
2635 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2636 &sighand->action[SIGKILL - 1]);
2637 recalc_sigpending();
2638 goto fatal;
2639 }
2640
2641 for (;;) {
2642 struct k_sigaction *ka;
2643
2644 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2645 do_signal_stop(0))
2646 goto relock;
2647
2648 if (unlikely(current->jobctl &
2649 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2650 if (current->jobctl & JOBCTL_TRAP_MASK) {
2651 do_jobctl_trap();
2652 spin_unlock_irq(&sighand->siglock);
2653 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2654 do_freezer_trap();
2655
2656 goto relock;
2657 }
2658
2659 /*
2660 * If the task is leaving the frozen state, let's update
2661 * cgroup counters and reset the frozen bit.
2662 */
2663 if (unlikely(cgroup_task_frozen(current))) {
2664 spin_unlock_irq(&sighand->siglock);
2665 cgroup_leave_frozen(false);
2666 goto relock;
2667 }
2668
2669 /*
2670 * Signals generated by the execution of an instruction
2671 * need to be delivered before any other pending signals
2672 * so that the instruction pointer in the signal stack
2673 * frame points to the faulting instruction.
2674 */
2675 signr = dequeue_synchronous_signal(&ksig->info);
2676 if (!signr)
2677 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2678
2679 if (!signr)
2680 break; /* will return 0 */
2681
2682 if (unlikely(current->ptrace) && signr != SIGKILL) {
2683 signr = ptrace_signal(signr, &ksig->info);
2684 if (!signr)
2685 continue;
2686 }
2687
2688 ka = &sighand->action[signr-1];
2689
2690 /* Trace actually delivered signals. */
2691 trace_signal_deliver(signr, &ksig->info, ka);
2692
2693 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2694 continue;
2695 if (ka->sa.sa_handler != SIG_DFL) {
2696 /* Run the handler. */
2697 ksig->ka = *ka;
2698
2699 if (ka->sa.sa_flags & SA_ONESHOT)
2700 ka->sa.sa_handler = SIG_DFL;
2701
2702 break; /* will return non-zero "signr" value */
2703 }
2704
2705 /*
2706 * Now we are doing the default action for this signal.
2707 */
2708 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2709 continue;
2710
2711 /*
2712 * Global init gets no signals it doesn't want.
2713 * Container-init gets no signals it doesn't want from same
2714 * container.
2715 *
2716 * Note that if global/container-init sees a sig_kernel_only()
2717 * signal here, the signal must have been generated internally
2718 * or must have come from an ancestor namespace. In either
2719 * case, the signal cannot be dropped.
2720 */
2721 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2722 !sig_kernel_only(signr))
2723 continue;
2724
2725 if (sig_kernel_stop(signr)) {
2726 /*
2727 * The default action is to stop all threads in
2728 * the thread group. The job control signals
2729 * do nothing in an orphaned pgrp, but SIGSTOP
2730 * always works. Note that siglock needs to be
2731 * dropped during the call to is_orphaned_pgrp()
2732 * because of lock ordering with tasklist_lock.
2733 * This allows an intervening SIGCONT to be posted.
2734 * We need to check for that and bail out if necessary.
2735 */
2736 if (signr != SIGSTOP) {
2737 spin_unlock_irq(&sighand->siglock);
2738
2739 /* signals can be posted during this window */
2740
2741 if (is_current_pgrp_orphaned())
2742 goto relock;
2743
2744 spin_lock_irq(&sighand->siglock);
2745 }
2746
2747 if (likely(do_signal_stop(ksig->info.si_signo))) {
2748 /* It released the siglock. */
2749 goto relock;
2750 }
2751
2752 /*
2753 * We didn't actually stop, due to a race
2754 * with SIGCONT or something like that.
2755 */
2756 continue;
2757 }
2758
2759 fatal:
2760 spin_unlock_irq(&sighand->siglock);
2761 if (unlikely(cgroup_task_frozen(current)))
2762 cgroup_leave_frozen(true);
2763
2764 /*
2765 * Anything else is fatal, maybe with a core dump.
2766 */
2767 current->flags |= PF_SIGNALED;
2768
2769 if (sig_kernel_coredump(signr)) {
2770 if (print_fatal_signals)
2771 print_fatal_signal(ksig->info.si_signo);
2772 proc_coredump_connector(current);
2773 /*
2774 * If it was able to dump core, this kills all
2775 * other threads in the group and synchronizes with
2776 * their demise. If we lost the race with another
2777 * thread getting here, it set group_exit_code
2778 * first and our do_group_exit call below will use
2779 * that value and ignore the one we pass it.
2780 */
2781 do_coredump(&ksig->info);
2782 }
2783
2784 /*
2785 * PF_IO_WORKER threads will catch and exit on fatal signals
2786 * themselves. They have cleanup that must be performed, so
2787 * we cannot call do_exit() on their behalf.
2788 */
2789 if (current->flags & PF_IO_WORKER)
2790 goto out;
2791
2792 /*
2793 * Death signals, no core dump.
2794 */
2795 do_group_exit(ksig->info.si_signo);
2796 /* NOTREACHED */
2797 }
2798 spin_unlock_irq(&sighand->siglock);
2799out:
2800 ksig->sig = signr;
2801
2802 if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2803 hide_si_addr_tag_bits(ksig);
2804
2805 return ksig->sig > 0;
2806}
2807
2808/**
2809 * signal_delivered -
2810 * @ksig: kernel signal struct
2811 * @stepping: nonzero if debugger single-step or block-step in use
2812 *
2813 * This function should be called when a signal has successfully been
2814 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2815 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2816 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2817 */
2818static void signal_delivered(struct ksignal *ksig, int stepping)
2819{
2820 sigset_t blocked;
2821
2822 /* A signal was successfully delivered, and the
2823 saved sigmask was stored on the signal frame,
2824 and will be restored by sigreturn. So we can
2825 simply clear the restore sigmask flag. */
2826 clear_restore_sigmask();
2827
2828 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2829 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2830 sigaddset(&blocked, ksig->sig);
2831 set_current_blocked(&blocked);
2832 if (current->sas_ss_flags & SS_AUTODISARM)
2833 sas_ss_reset(current);
2834 tracehook_signal_handler(stepping);
2835}
2836
2837void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2838{
2839 if (failed)
2840 force_sigsegv(ksig->sig);
2841 else
2842 signal_delivered(ksig, stepping);
2843}
2844
2845/*
2846 * It could be that complete_signal() picked us to notify about the
2847 * group-wide signal. Other threads should be notified now to take
2848 * the shared signals in @which since we will not.
2849 */
2850static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2851{
2852 sigset_t retarget;
2853 struct task_struct *t;
2854
2855 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2856 if (sigisemptyset(&retarget))
2857 return;
2858
2859 t = tsk;
2860 while_each_thread(tsk, t) {
2861 if (t->flags & PF_EXITING)
2862 continue;
2863
2864 if (!has_pending_signals(&retarget, &t->blocked))
2865 continue;
2866 /* Remove the signals this thread can handle. */
2867 sigandsets(&retarget, &retarget, &t->blocked);
2868
2869 if (!task_sigpending(t))
2870 signal_wake_up(t, 0);
2871
2872 if (sigisemptyset(&retarget))
2873 break;
2874 }
2875}
2876
2877void exit_signals(struct task_struct *tsk)
2878{
2879 int group_stop = 0;
2880 sigset_t unblocked;
2881
2882 /*
2883 * @tsk is about to have PF_EXITING set - lock out users which
2884 * expect stable threadgroup.
2885 */
2886 cgroup_threadgroup_change_begin(tsk);
2887
2888 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2889 tsk->flags |= PF_EXITING;
2890 cgroup_threadgroup_change_end(tsk);
2891 return;
2892 }
2893
2894 spin_lock_irq(&tsk->sighand->siglock);
2895 /*
2896 * From now this task is not visible for group-wide signals,
2897 * see wants_signal(), do_signal_stop().
2898 */
2899 tsk->flags |= PF_EXITING;
2900
2901 cgroup_threadgroup_change_end(tsk);
2902
2903 if (!task_sigpending(tsk))
2904 goto out;
2905
2906 unblocked = tsk->blocked;
2907 signotset(&unblocked);
2908 retarget_shared_pending(tsk, &unblocked);
2909
2910 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2911 task_participate_group_stop(tsk))
2912 group_stop = CLD_STOPPED;
2913out:
2914 spin_unlock_irq(&tsk->sighand->siglock);
2915
2916 /*
2917 * If group stop has completed, deliver the notification. This
2918 * should always go to the real parent of the group leader.
2919 */
2920 if (unlikely(group_stop)) {
2921 read_lock(&tasklist_lock);
2922 do_notify_parent_cldstop(tsk, false, group_stop);
2923 read_unlock(&tasklist_lock);
2924 }
2925}
2926
2927/*
2928 * System call entry points.
2929 */
2930
2931/**
2932 * sys_restart_syscall - restart a system call
2933 */
2934SYSCALL_DEFINE0(restart_syscall)
2935{
2936 struct restart_block *restart = ¤t->restart_block;
2937 return restart->fn(restart);
2938}
2939
2940long do_no_restart_syscall(struct restart_block *param)
2941{
2942 return -EINTR;
2943}
2944
2945static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2946{
2947 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
2948 sigset_t newblocked;
2949 /* A set of now blocked but previously unblocked signals. */
2950 sigandnsets(&newblocked, newset, ¤t->blocked);
2951 retarget_shared_pending(tsk, &newblocked);
2952 }
2953 tsk->blocked = *newset;
2954 recalc_sigpending();
2955}
2956
2957/**
2958 * set_current_blocked - change current->blocked mask
2959 * @newset: new mask
2960 *
2961 * It is wrong to change ->blocked directly, this helper should be used
2962 * to ensure the process can't miss a shared signal we are going to block.
2963 */
2964void set_current_blocked(sigset_t *newset)
2965{
2966 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2967 __set_current_blocked(newset);
2968}
2969
2970void __set_current_blocked(const sigset_t *newset)
2971{
2972 struct task_struct *tsk = current;
2973
2974 /*
2975 * In case the signal mask hasn't changed, there is nothing we need
2976 * to do. The current->blocked shouldn't be modified by other task.
2977 */
2978 if (sigequalsets(&tsk->blocked, newset))
2979 return;
2980
2981 spin_lock_irq(&tsk->sighand->siglock);
2982 __set_task_blocked(tsk, newset);
2983 spin_unlock_irq(&tsk->sighand->siglock);
2984}
2985
2986/*
2987 * This is also useful for kernel threads that want to temporarily
2988 * (or permanently) block certain signals.
2989 *
2990 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2991 * interface happily blocks "unblockable" signals like SIGKILL
2992 * and friends.
2993 */
2994int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2995{
2996 struct task_struct *tsk = current;
2997 sigset_t newset;
2998
2999 /* Lockless, only current can change ->blocked, never from irq */
3000 if (oldset)
3001 *oldset = tsk->blocked;
3002
3003 switch (how) {
3004 case SIG_BLOCK:
3005 sigorsets(&newset, &tsk->blocked, set);
3006 break;
3007 case SIG_UNBLOCK:
3008 sigandnsets(&newset, &tsk->blocked, set);
3009 break;
3010 case SIG_SETMASK:
3011 newset = *set;
3012 break;
3013 default:
3014 return -EINVAL;
3015 }
3016
3017 __set_current_blocked(&newset);
3018 return 0;
3019}
3020EXPORT_SYMBOL(sigprocmask);
3021
3022/*
3023 * The api helps set app-provided sigmasks.
3024 *
3025 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3026 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3027 *
3028 * Note that it does set_restore_sigmask() in advance, so it must be always
3029 * paired with restore_saved_sigmask_unless() before return from syscall.
3030 */
3031int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3032{
3033 sigset_t kmask;
3034
3035 if (!umask)
3036 return 0;
3037 if (sigsetsize != sizeof(sigset_t))
3038 return -EINVAL;
3039 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3040 return -EFAULT;
3041
3042 set_restore_sigmask();
3043 current->saved_sigmask = current->blocked;
3044 set_current_blocked(&kmask);
3045
3046 return 0;
3047}
3048
3049#ifdef CONFIG_COMPAT
3050int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3051 size_t sigsetsize)
3052{
3053 sigset_t kmask;
3054
3055 if (!umask)
3056 return 0;
3057 if (sigsetsize != sizeof(compat_sigset_t))
3058 return -EINVAL;
3059 if (get_compat_sigset(&kmask, umask))
3060 return -EFAULT;
3061
3062 set_restore_sigmask();
3063 current->saved_sigmask = current->blocked;
3064 set_current_blocked(&kmask);
3065
3066 return 0;
3067}
3068#endif
3069
3070/**
3071 * sys_rt_sigprocmask - change the list of currently blocked signals
3072 * @how: whether to add, remove, or set signals
3073 * @nset: stores pending signals
3074 * @oset: previous value of signal mask if non-null
3075 * @sigsetsize: size of sigset_t type
3076 */
3077SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3078 sigset_t __user *, oset, size_t, sigsetsize)
3079{
3080 sigset_t old_set, new_set;
3081 int error;
3082
3083 /* XXX: Don't preclude handling different sized sigset_t's. */
3084 if (sigsetsize != sizeof(sigset_t))
3085 return -EINVAL;
3086
3087 old_set = current->blocked;
3088
3089 if (nset) {
3090 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3091 return -EFAULT;
3092 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3093
3094 error = sigprocmask(how, &new_set, NULL);
3095 if (error)
3096 return error;
3097 }
3098
3099 if (oset) {
3100 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3101 return -EFAULT;
3102 }
3103
3104 return 0;
3105}
3106
3107#ifdef CONFIG_COMPAT
3108COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3109 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3110{
3111 sigset_t old_set = current->blocked;
3112
3113 /* XXX: Don't preclude handling different sized sigset_t's. */
3114 if (sigsetsize != sizeof(sigset_t))
3115 return -EINVAL;
3116
3117 if (nset) {
3118 sigset_t new_set;
3119 int error;
3120 if (get_compat_sigset(&new_set, nset))
3121 return -EFAULT;
3122 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3123
3124 error = sigprocmask(how, &new_set, NULL);
3125 if (error)
3126 return error;
3127 }
3128 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3129}
3130#endif
3131
3132static void do_sigpending(sigset_t *set)
3133{
3134 spin_lock_irq(¤t->sighand->siglock);
3135 sigorsets(set, ¤t->pending.signal,
3136 ¤t->signal->shared_pending.signal);
3137 spin_unlock_irq(¤t->sighand->siglock);
3138
3139 /* Outside the lock because only this thread touches it. */
3140 sigandsets(set, ¤t->blocked, set);
3141}
3142
3143/**
3144 * sys_rt_sigpending - examine a pending signal that has been raised
3145 * while blocked
3146 * @uset: stores pending signals
3147 * @sigsetsize: size of sigset_t type or larger
3148 */
3149SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3150{
3151 sigset_t set;
3152
3153 if (sigsetsize > sizeof(*uset))
3154 return -EINVAL;
3155
3156 do_sigpending(&set);
3157
3158 if (copy_to_user(uset, &set, sigsetsize))
3159 return -EFAULT;
3160
3161 return 0;
3162}
3163
3164#ifdef CONFIG_COMPAT
3165COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3166 compat_size_t, sigsetsize)
3167{
3168 sigset_t set;
3169
3170 if (sigsetsize > sizeof(*uset))
3171 return -EINVAL;
3172
3173 do_sigpending(&set);
3174
3175 return put_compat_sigset(uset, &set, sigsetsize);
3176}
3177#endif
3178
3179static const struct {
3180 unsigned char limit, layout;
3181} sig_sicodes[] = {
3182 [SIGILL] = { NSIGILL, SIL_FAULT },
3183 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3184 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3185 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3186 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3187#if defined(SIGEMT)
3188 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3189#endif
3190 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3191 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3192 [SIGSYS] = { NSIGSYS, SIL_SYS },
3193};
3194
3195static bool known_siginfo_layout(unsigned sig, int si_code)
3196{
3197 if (si_code == SI_KERNEL)
3198 return true;
3199 else if ((si_code > SI_USER)) {
3200 if (sig_specific_sicodes(sig)) {
3201 if (si_code <= sig_sicodes[sig].limit)
3202 return true;
3203 }
3204 else if (si_code <= NSIGPOLL)
3205 return true;
3206 }
3207 else if (si_code >= SI_DETHREAD)
3208 return true;
3209 else if (si_code == SI_ASYNCNL)
3210 return true;
3211 return false;
3212}
3213
3214enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3215{
3216 enum siginfo_layout layout = SIL_KILL;
3217 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3218 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3219 (si_code <= sig_sicodes[sig].limit)) {
3220 layout = sig_sicodes[sig].layout;
3221 /* Handle the exceptions */
3222 if ((sig == SIGBUS) &&
3223 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3224 layout = SIL_FAULT_MCEERR;
3225 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3226 layout = SIL_FAULT_BNDERR;
3227#ifdef SEGV_PKUERR
3228 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3229 layout = SIL_FAULT_PKUERR;
3230#endif
3231 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3232 layout = SIL_PERF_EVENT;
3233#ifdef __ARCH_SI_TRAPNO
3234 else if (layout == SIL_FAULT)
3235 layout = SIL_FAULT_TRAPNO;
3236#endif
3237 }
3238 else if (si_code <= NSIGPOLL)
3239 layout = SIL_POLL;
3240 } else {
3241 if (si_code == SI_TIMER)
3242 layout = SIL_TIMER;
3243 else if (si_code == SI_SIGIO)
3244 layout = SIL_POLL;
3245 else if (si_code < 0)
3246 layout = SIL_RT;
3247 }
3248 return layout;
3249}
3250
3251static inline char __user *si_expansion(const siginfo_t __user *info)
3252{
3253 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3254}
3255
3256int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3257{
3258 char __user *expansion = si_expansion(to);
3259 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3260 return -EFAULT;
3261 if (clear_user(expansion, SI_EXPANSION_SIZE))
3262 return -EFAULT;
3263 return 0;
3264}
3265
3266static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3267 const siginfo_t __user *from)
3268{
3269 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3270 char __user *expansion = si_expansion(from);
3271 char buf[SI_EXPANSION_SIZE];
3272 int i;
3273 /*
3274 * An unknown si_code might need more than
3275 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3276 * extra bytes are 0. This guarantees copy_siginfo_to_user
3277 * will return this data to userspace exactly.
3278 */
3279 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3280 return -EFAULT;
3281 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3282 if (buf[i] != 0)
3283 return -E2BIG;
3284 }
3285 }
3286 return 0;
3287}
3288
3289static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3290 const siginfo_t __user *from)
3291{
3292 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3293 return -EFAULT;
3294 to->si_signo = signo;
3295 return post_copy_siginfo_from_user(to, from);
3296}
3297
3298int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3299{
3300 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3301 return -EFAULT;
3302 return post_copy_siginfo_from_user(to, from);
3303}
3304
3305#ifdef CONFIG_COMPAT
3306/**
3307 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3308 * @to: compat siginfo destination
3309 * @from: kernel siginfo source
3310 *
3311 * Note: This function does not work properly for the SIGCHLD on x32, but
3312 * fortunately it doesn't have to. The only valid callers for this function are
3313 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3314 * The latter does not care because SIGCHLD will never cause a coredump.
3315 */
3316void copy_siginfo_to_external32(struct compat_siginfo *to,
3317 const struct kernel_siginfo *from)
3318{
3319 memset(to, 0, sizeof(*to));
3320
3321 to->si_signo = from->si_signo;
3322 to->si_errno = from->si_errno;
3323 to->si_code = from->si_code;
3324 switch(siginfo_layout(from->si_signo, from->si_code)) {
3325 case SIL_KILL:
3326 to->si_pid = from->si_pid;
3327 to->si_uid = from->si_uid;
3328 break;
3329 case SIL_TIMER:
3330 to->si_tid = from->si_tid;
3331 to->si_overrun = from->si_overrun;
3332 to->si_int = from->si_int;
3333 break;
3334 case SIL_POLL:
3335 to->si_band = from->si_band;
3336 to->si_fd = from->si_fd;
3337 break;
3338 case SIL_FAULT:
3339 to->si_addr = ptr_to_compat(from->si_addr);
3340 break;
3341 case SIL_FAULT_TRAPNO:
3342 to->si_addr = ptr_to_compat(from->si_addr);
3343 to->si_trapno = from->si_trapno;
3344 break;
3345 case SIL_FAULT_MCEERR:
3346 to->si_addr = ptr_to_compat(from->si_addr);
3347 to->si_addr_lsb = from->si_addr_lsb;
3348 break;
3349 case SIL_FAULT_BNDERR:
3350 to->si_addr = ptr_to_compat(from->si_addr);
3351 to->si_lower = ptr_to_compat(from->si_lower);
3352 to->si_upper = ptr_to_compat(from->si_upper);
3353 break;
3354 case SIL_FAULT_PKUERR:
3355 to->si_addr = ptr_to_compat(from->si_addr);
3356 to->si_pkey = from->si_pkey;
3357 break;
3358 case SIL_PERF_EVENT:
3359 to->si_addr = ptr_to_compat(from->si_addr);
3360 to->si_perf_data = from->si_perf_data;
3361 to->si_perf_type = from->si_perf_type;
3362 break;
3363 case SIL_CHLD:
3364 to->si_pid = from->si_pid;
3365 to->si_uid = from->si_uid;
3366 to->si_status = from->si_status;
3367 to->si_utime = from->si_utime;
3368 to->si_stime = from->si_stime;
3369 break;
3370 case SIL_RT:
3371 to->si_pid = from->si_pid;
3372 to->si_uid = from->si_uid;
3373 to->si_int = from->si_int;
3374 break;
3375 case SIL_SYS:
3376 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3377 to->si_syscall = from->si_syscall;
3378 to->si_arch = from->si_arch;
3379 break;
3380 }
3381}
3382
3383int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3384 const struct kernel_siginfo *from)
3385{
3386 struct compat_siginfo new;
3387
3388 copy_siginfo_to_external32(&new, from);
3389 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3390 return -EFAULT;
3391 return 0;
3392}
3393
3394static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3395 const struct compat_siginfo *from)
3396{
3397 clear_siginfo(to);
3398 to->si_signo = from->si_signo;
3399 to->si_errno = from->si_errno;
3400 to->si_code = from->si_code;
3401 switch(siginfo_layout(from->si_signo, from->si_code)) {
3402 case SIL_KILL:
3403 to->si_pid = from->si_pid;
3404 to->si_uid = from->si_uid;
3405 break;
3406 case SIL_TIMER:
3407 to->si_tid = from->si_tid;
3408 to->si_overrun = from->si_overrun;
3409 to->si_int = from->si_int;
3410 break;
3411 case SIL_POLL:
3412 to->si_band = from->si_band;
3413 to->si_fd = from->si_fd;
3414 break;
3415 case SIL_FAULT:
3416 to->si_addr = compat_ptr(from->si_addr);
3417 break;
3418 case SIL_FAULT_TRAPNO:
3419 to->si_addr = compat_ptr(from->si_addr);
3420 to->si_trapno = from->si_trapno;
3421 break;
3422 case SIL_FAULT_MCEERR:
3423 to->si_addr = compat_ptr(from->si_addr);
3424 to->si_addr_lsb = from->si_addr_lsb;
3425 break;
3426 case SIL_FAULT_BNDERR:
3427 to->si_addr = compat_ptr(from->si_addr);
3428 to->si_lower = compat_ptr(from->si_lower);
3429 to->si_upper = compat_ptr(from->si_upper);
3430 break;
3431 case SIL_FAULT_PKUERR:
3432 to->si_addr = compat_ptr(from->si_addr);
3433 to->si_pkey = from->si_pkey;
3434 break;
3435 case SIL_PERF_EVENT:
3436 to->si_addr = compat_ptr(from->si_addr);
3437 to->si_perf_data = from->si_perf_data;
3438 to->si_perf_type = from->si_perf_type;
3439 break;
3440 case SIL_CHLD:
3441 to->si_pid = from->si_pid;
3442 to->si_uid = from->si_uid;
3443 to->si_status = from->si_status;
3444#ifdef CONFIG_X86_X32_ABI
3445 if (in_x32_syscall()) {
3446 to->si_utime = from->_sifields._sigchld_x32._utime;
3447 to->si_stime = from->_sifields._sigchld_x32._stime;
3448 } else
3449#endif
3450 {
3451 to->si_utime = from->si_utime;
3452 to->si_stime = from->si_stime;
3453 }
3454 break;
3455 case SIL_RT:
3456 to->si_pid = from->si_pid;
3457 to->si_uid = from->si_uid;
3458 to->si_int = from->si_int;
3459 break;
3460 case SIL_SYS:
3461 to->si_call_addr = compat_ptr(from->si_call_addr);
3462 to->si_syscall = from->si_syscall;
3463 to->si_arch = from->si_arch;
3464 break;
3465 }
3466 return 0;
3467}
3468
3469static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3470 const struct compat_siginfo __user *ufrom)
3471{
3472 struct compat_siginfo from;
3473
3474 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3475 return -EFAULT;
3476
3477 from.si_signo = signo;
3478 return post_copy_siginfo_from_user32(to, &from);
3479}
3480
3481int copy_siginfo_from_user32(struct kernel_siginfo *to,
3482 const struct compat_siginfo __user *ufrom)
3483{
3484 struct compat_siginfo from;
3485
3486 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3487 return -EFAULT;
3488
3489 return post_copy_siginfo_from_user32(to, &from);
3490}
3491#endif /* CONFIG_COMPAT */
3492
3493/**
3494 * do_sigtimedwait - wait for queued signals specified in @which
3495 * @which: queued signals to wait for
3496 * @info: if non-null, the signal's siginfo is returned here
3497 * @ts: upper bound on process time suspension
3498 */
3499static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3500 const struct timespec64 *ts)
3501{
3502 ktime_t *to = NULL, timeout = KTIME_MAX;
3503 struct task_struct *tsk = current;
3504 sigset_t mask = *which;
3505 int sig, ret = 0;
3506
3507 if (ts) {
3508 if (!timespec64_valid(ts))
3509 return -EINVAL;
3510 timeout = timespec64_to_ktime(*ts);
3511 to = &timeout;
3512 }
3513
3514 /*
3515 * Invert the set of allowed signals to get those we want to block.
3516 */
3517 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3518 signotset(&mask);
3519
3520 spin_lock_irq(&tsk->sighand->siglock);
3521 sig = dequeue_signal(tsk, &mask, info);
3522 if (!sig && timeout) {
3523 /*
3524 * None ready, temporarily unblock those we're interested
3525 * while we are sleeping in so that we'll be awakened when
3526 * they arrive. Unblocking is always fine, we can avoid
3527 * set_current_blocked().
3528 */
3529 tsk->real_blocked = tsk->blocked;
3530 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3531 recalc_sigpending();
3532 spin_unlock_irq(&tsk->sighand->siglock);
3533
3534 __set_current_state(TASK_INTERRUPTIBLE);
3535 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3536 HRTIMER_MODE_REL);
3537 spin_lock_irq(&tsk->sighand->siglock);
3538 __set_task_blocked(tsk, &tsk->real_blocked);
3539 sigemptyset(&tsk->real_blocked);
3540 sig = dequeue_signal(tsk, &mask, info);
3541 }
3542 spin_unlock_irq(&tsk->sighand->siglock);
3543
3544 if (sig)
3545 return sig;
3546 return ret ? -EINTR : -EAGAIN;
3547}
3548
3549/**
3550 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3551 * in @uthese
3552 * @uthese: queued signals to wait for
3553 * @uinfo: if non-null, the signal's siginfo is returned here
3554 * @uts: upper bound on process time suspension
3555 * @sigsetsize: size of sigset_t type
3556 */
3557SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3558 siginfo_t __user *, uinfo,
3559 const struct __kernel_timespec __user *, uts,
3560 size_t, sigsetsize)
3561{
3562 sigset_t these;
3563 struct timespec64 ts;
3564 kernel_siginfo_t info;
3565 int ret;
3566
3567 /* XXX: Don't preclude handling different sized sigset_t's. */
3568 if (sigsetsize != sizeof(sigset_t))
3569 return -EINVAL;
3570
3571 if (copy_from_user(&these, uthese, sizeof(these)))
3572 return -EFAULT;
3573
3574 if (uts) {
3575 if (get_timespec64(&ts, uts))
3576 return -EFAULT;
3577 }
3578
3579 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3580
3581 if (ret > 0 && uinfo) {
3582 if (copy_siginfo_to_user(uinfo, &info))
3583 ret = -EFAULT;
3584 }
3585
3586 return ret;
3587}
3588
3589#ifdef CONFIG_COMPAT_32BIT_TIME
3590SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3591 siginfo_t __user *, uinfo,
3592 const struct old_timespec32 __user *, uts,
3593 size_t, sigsetsize)
3594{
3595 sigset_t these;
3596 struct timespec64 ts;
3597 kernel_siginfo_t info;
3598 int ret;
3599
3600 if (sigsetsize != sizeof(sigset_t))
3601 return -EINVAL;
3602
3603 if (copy_from_user(&these, uthese, sizeof(these)))
3604 return -EFAULT;
3605
3606 if (uts) {
3607 if (get_old_timespec32(&ts, uts))
3608 return -EFAULT;
3609 }
3610
3611 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3612
3613 if (ret > 0 && uinfo) {
3614 if (copy_siginfo_to_user(uinfo, &info))
3615 ret = -EFAULT;
3616 }
3617
3618 return ret;
3619}
3620#endif
3621
3622#ifdef CONFIG_COMPAT
3623COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3624 struct compat_siginfo __user *, uinfo,
3625 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3626{
3627 sigset_t s;
3628 struct timespec64 t;
3629 kernel_siginfo_t info;
3630 long ret;
3631
3632 if (sigsetsize != sizeof(sigset_t))
3633 return -EINVAL;
3634
3635 if (get_compat_sigset(&s, uthese))
3636 return -EFAULT;
3637
3638 if (uts) {
3639 if (get_timespec64(&t, uts))
3640 return -EFAULT;
3641 }
3642
3643 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3644
3645 if (ret > 0 && uinfo) {
3646 if (copy_siginfo_to_user32(uinfo, &info))
3647 ret = -EFAULT;
3648 }
3649
3650 return ret;
3651}
3652
3653#ifdef CONFIG_COMPAT_32BIT_TIME
3654COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3655 struct compat_siginfo __user *, uinfo,
3656 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3657{
3658 sigset_t s;
3659 struct timespec64 t;
3660 kernel_siginfo_t info;
3661 long ret;
3662
3663 if (sigsetsize != sizeof(sigset_t))
3664 return -EINVAL;
3665
3666 if (get_compat_sigset(&s, uthese))
3667 return -EFAULT;
3668
3669 if (uts) {
3670 if (get_old_timespec32(&t, uts))
3671 return -EFAULT;
3672 }
3673
3674 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3675
3676 if (ret > 0 && uinfo) {
3677 if (copy_siginfo_to_user32(uinfo, &info))
3678 ret = -EFAULT;
3679 }
3680
3681 return ret;
3682}
3683#endif
3684#endif
3685
3686static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3687{
3688 clear_siginfo(info);
3689 info->si_signo = sig;
3690 info->si_errno = 0;
3691 info->si_code = SI_USER;
3692 info->si_pid = task_tgid_vnr(current);
3693 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3694}
3695
3696/**
3697 * sys_kill - send a signal to a process
3698 * @pid: the PID of the process
3699 * @sig: signal to be sent
3700 */
3701SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3702{
3703 struct kernel_siginfo info;
3704
3705 prepare_kill_siginfo(sig, &info);
3706
3707 return kill_something_info(sig, &info, pid);
3708}
3709
3710/*
3711 * Verify that the signaler and signalee either are in the same pid namespace
3712 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3713 * namespace.
3714 */
3715static bool access_pidfd_pidns(struct pid *pid)
3716{
3717 struct pid_namespace *active = task_active_pid_ns(current);
3718 struct pid_namespace *p = ns_of_pid(pid);
3719
3720 for (;;) {
3721 if (!p)
3722 return false;
3723 if (p == active)
3724 break;
3725 p = p->parent;
3726 }
3727
3728 return true;
3729}
3730
3731static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3732 siginfo_t __user *info)
3733{
3734#ifdef CONFIG_COMPAT
3735 /*
3736 * Avoid hooking up compat syscalls and instead handle necessary
3737 * conversions here. Note, this is a stop-gap measure and should not be
3738 * considered a generic solution.
3739 */
3740 if (in_compat_syscall())
3741 return copy_siginfo_from_user32(
3742 kinfo, (struct compat_siginfo __user *)info);
3743#endif
3744 return copy_siginfo_from_user(kinfo, info);
3745}
3746
3747static struct pid *pidfd_to_pid(const struct file *file)
3748{
3749 struct pid *pid;
3750
3751 pid = pidfd_pid(file);
3752 if (!IS_ERR(pid))
3753 return pid;
3754
3755 return tgid_pidfd_to_pid(file);
3756}
3757
3758/**
3759 * sys_pidfd_send_signal - Signal a process through a pidfd
3760 * @pidfd: file descriptor of the process
3761 * @sig: signal to send
3762 * @info: signal info
3763 * @flags: future flags
3764 *
3765 * The syscall currently only signals via PIDTYPE_PID which covers
3766 * kill(<positive-pid>, <signal>. It does not signal threads or process
3767 * groups.
3768 * In order to extend the syscall to threads and process groups the @flags
3769 * argument should be used. In essence, the @flags argument will determine
3770 * what is signaled and not the file descriptor itself. Put in other words,
3771 * grouping is a property of the flags argument not a property of the file
3772 * descriptor.
3773 *
3774 * Return: 0 on success, negative errno on failure
3775 */
3776SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3777 siginfo_t __user *, info, unsigned int, flags)
3778{
3779 int ret;
3780 struct fd f;
3781 struct pid *pid;
3782 kernel_siginfo_t kinfo;
3783
3784 /* Enforce flags be set to 0 until we add an extension. */
3785 if (flags)
3786 return -EINVAL;
3787
3788 f = fdget(pidfd);
3789 if (!f.file)
3790 return -EBADF;
3791
3792 /* Is this a pidfd? */
3793 pid = pidfd_to_pid(f.file);
3794 if (IS_ERR(pid)) {
3795 ret = PTR_ERR(pid);
3796 goto err;
3797 }
3798
3799 ret = -EINVAL;
3800 if (!access_pidfd_pidns(pid))
3801 goto err;
3802
3803 if (info) {
3804 ret = copy_siginfo_from_user_any(&kinfo, info);
3805 if (unlikely(ret))
3806 goto err;
3807
3808 ret = -EINVAL;
3809 if (unlikely(sig != kinfo.si_signo))
3810 goto err;
3811
3812 /* Only allow sending arbitrary signals to yourself. */
3813 ret = -EPERM;
3814 if ((task_pid(current) != pid) &&
3815 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3816 goto err;
3817 } else {
3818 prepare_kill_siginfo(sig, &kinfo);
3819 }
3820
3821 ret = kill_pid_info(sig, &kinfo, pid);
3822
3823err:
3824 fdput(f);
3825 return ret;
3826}
3827
3828static int
3829do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3830{
3831 struct task_struct *p;
3832 int error = -ESRCH;
3833
3834 rcu_read_lock();
3835 p = find_task_by_vpid(pid);
3836 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3837 error = check_kill_permission(sig, info, p);
3838 /*
3839 * The null signal is a permissions and process existence
3840 * probe. No signal is actually delivered.
3841 */
3842 if (!error && sig) {
3843 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3844 /*
3845 * If lock_task_sighand() failed we pretend the task
3846 * dies after receiving the signal. The window is tiny,
3847 * and the signal is private anyway.
3848 */
3849 if (unlikely(error == -ESRCH))
3850 error = 0;
3851 }
3852 }
3853 rcu_read_unlock();
3854
3855 return error;
3856}
3857
3858static int do_tkill(pid_t tgid, pid_t pid, int sig)
3859{
3860 struct kernel_siginfo info;
3861
3862 clear_siginfo(&info);
3863 info.si_signo = sig;
3864 info.si_errno = 0;
3865 info.si_code = SI_TKILL;
3866 info.si_pid = task_tgid_vnr(current);
3867 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3868
3869 return do_send_specific(tgid, pid, sig, &info);
3870}
3871
3872/**
3873 * sys_tgkill - send signal to one specific thread
3874 * @tgid: the thread group ID of the thread
3875 * @pid: the PID of the thread
3876 * @sig: signal to be sent
3877 *
3878 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3879 * exists but it's not belonging to the target process anymore. This
3880 * method solves the problem of threads exiting and PIDs getting reused.
3881 */
3882SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3883{
3884 /* This is only valid for single tasks */
3885 if (pid <= 0 || tgid <= 0)
3886 return -EINVAL;
3887
3888 return do_tkill(tgid, pid, sig);
3889}
3890
3891/**
3892 * sys_tkill - send signal to one specific task
3893 * @pid: the PID of the task
3894 * @sig: signal to be sent
3895 *
3896 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3897 */
3898SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3899{
3900 /* This is only valid for single tasks */
3901 if (pid <= 0)
3902 return -EINVAL;
3903
3904 return do_tkill(0, pid, sig);
3905}
3906
3907static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3908{
3909 /* Not even root can pretend to send signals from the kernel.
3910 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3911 */
3912 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3913 (task_pid_vnr(current) != pid))
3914 return -EPERM;
3915
3916 /* POSIX.1b doesn't mention process groups. */
3917 return kill_proc_info(sig, info, pid);
3918}
3919
3920/**
3921 * sys_rt_sigqueueinfo - send signal information to a signal
3922 * @pid: the PID of the thread
3923 * @sig: signal to be sent
3924 * @uinfo: signal info to be sent
3925 */
3926SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3927 siginfo_t __user *, uinfo)
3928{
3929 kernel_siginfo_t info;
3930 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3931 if (unlikely(ret))
3932 return ret;
3933 return do_rt_sigqueueinfo(pid, sig, &info);
3934}
3935
3936#ifdef CONFIG_COMPAT
3937COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3938 compat_pid_t, pid,
3939 int, sig,
3940 struct compat_siginfo __user *, uinfo)
3941{
3942 kernel_siginfo_t info;
3943 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3944 if (unlikely(ret))
3945 return ret;
3946 return do_rt_sigqueueinfo(pid, sig, &info);
3947}
3948#endif
3949
3950static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
3951{
3952 /* This is only valid for single tasks */
3953 if (pid <= 0 || tgid <= 0)
3954 return -EINVAL;
3955
3956 /* Not even root can pretend to send signals from the kernel.
3957 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3958 */
3959 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3960 (task_pid_vnr(current) != pid))
3961 return -EPERM;
3962
3963 return do_send_specific(tgid, pid, sig, info);
3964}
3965
3966SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3967 siginfo_t __user *, uinfo)
3968{
3969 kernel_siginfo_t info;
3970 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3971 if (unlikely(ret))
3972 return ret;
3973 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3974}
3975
3976#ifdef CONFIG_COMPAT
3977COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3978 compat_pid_t, tgid,
3979 compat_pid_t, pid,
3980 int, sig,
3981 struct compat_siginfo __user *, uinfo)
3982{
3983 kernel_siginfo_t info;
3984 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3985 if (unlikely(ret))
3986 return ret;
3987 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3988}
3989#endif
3990
3991/*
3992 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3993 */
3994void kernel_sigaction(int sig, __sighandler_t action)
3995{
3996 spin_lock_irq(¤t->sighand->siglock);
3997 current->sighand->action[sig - 1].sa.sa_handler = action;
3998 if (action == SIG_IGN) {
3999 sigset_t mask;
4000
4001 sigemptyset(&mask);
4002 sigaddset(&mask, sig);
4003
4004 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4005 flush_sigqueue_mask(&mask, ¤t->pending);
4006 recalc_sigpending();
4007 }
4008 spin_unlock_irq(¤t->sighand->siglock);
4009}
4010EXPORT_SYMBOL(kernel_sigaction);
4011
4012void __weak sigaction_compat_abi(struct k_sigaction *act,
4013 struct k_sigaction *oact)
4014{
4015}
4016
4017int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4018{
4019 struct task_struct *p = current, *t;
4020 struct k_sigaction *k;
4021 sigset_t mask;
4022
4023 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4024 return -EINVAL;
4025
4026 k = &p->sighand->action[sig-1];
4027
4028 spin_lock_irq(&p->sighand->siglock);
4029 if (oact)
4030 *oact = *k;
4031
4032 /*
4033 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4034 * e.g. by having an architecture use the bit in their uapi.
4035 */
4036 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4037
4038 /*
4039 * Clear unknown flag bits in order to allow userspace to detect missing
4040 * support for flag bits and to allow the kernel to use non-uapi bits
4041 * internally.
4042 */
4043 if (act)
4044 act->sa.sa_flags &= UAPI_SA_FLAGS;
4045 if (oact)
4046 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4047
4048 sigaction_compat_abi(act, oact);
4049
4050 if (act) {
4051 sigdelsetmask(&act->sa.sa_mask,
4052 sigmask(SIGKILL) | sigmask(SIGSTOP));
4053 *k = *act;
4054 /*
4055 * POSIX 3.3.1.3:
4056 * "Setting a signal action to SIG_IGN for a signal that is
4057 * pending shall cause the pending signal to be discarded,
4058 * whether or not it is blocked."
4059 *
4060 * "Setting a signal action to SIG_DFL for a signal that is
4061 * pending and whose default action is to ignore the signal
4062 * (for example, SIGCHLD), shall cause the pending signal to
4063 * be discarded, whether or not it is blocked"
4064 */
4065 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4066 sigemptyset(&mask);
4067 sigaddset(&mask, sig);
4068 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4069 for_each_thread(p, t)
4070 flush_sigqueue_mask(&mask, &t->pending);
4071 }
4072 }
4073
4074 spin_unlock_irq(&p->sighand->siglock);
4075 return 0;
4076}
4077
4078static int
4079do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4080 size_t min_ss_size)
4081{
4082 struct task_struct *t = current;
4083
4084 if (oss) {
4085 memset(oss, 0, sizeof(stack_t));
4086 oss->ss_sp = (void __user *) t->sas_ss_sp;
4087 oss->ss_size = t->sas_ss_size;
4088 oss->ss_flags = sas_ss_flags(sp) |
4089 (current->sas_ss_flags & SS_FLAG_BITS);
4090 }
4091
4092 if (ss) {
4093 void __user *ss_sp = ss->ss_sp;
4094 size_t ss_size = ss->ss_size;
4095 unsigned ss_flags = ss->ss_flags;
4096 int ss_mode;
4097
4098 if (unlikely(on_sig_stack(sp)))
4099 return -EPERM;
4100
4101 ss_mode = ss_flags & ~SS_FLAG_BITS;
4102 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4103 ss_mode != 0))
4104 return -EINVAL;
4105
4106 if (ss_mode == SS_DISABLE) {
4107 ss_size = 0;
4108 ss_sp = NULL;
4109 } else {
4110 if (unlikely(ss_size < min_ss_size))
4111 return -ENOMEM;
4112 }
4113
4114 t->sas_ss_sp = (unsigned long) ss_sp;
4115 t->sas_ss_size = ss_size;
4116 t->sas_ss_flags = ss_flags;
4117 }
4118 return 0;
4119}
4120
4121SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4122{
4123 stack_t new, old;
4124 int err;
4125 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4126 return -EFAULT;
4127 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4128 current_user_stack_pointer(),
4129 MINSIGSTKSZ);
4130 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4131 err = -EFAULT;
4132 return err;
4133}
4134
4135int restore_altstack(const stack_t __user *uss)
4136{
4137 stack_t new;
4138 if (copy_from_user(&new, uss, sizeof(stack_t)))
4139 return -EFAULT;
4140 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4141 MINSIGSTKSZ);
4142 /* squash all but EFAULT for now */
4143 return 0;
4144}
4145
4146int __save_altstack(stack_t __user *uss, unsigned long sp)
4147{
4148 struct task_struct *t = current;
4149 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4150 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4151 __put_user(t->sas_ss_size, &uss->ss_size);
4152 return err;
4153}
4154
4155#ifdef CONFIG_COMPAT
4156static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4157 compat_stack_t __user *uoss_ptr)
4158{
4159 stack_t uss, uoss;
4160 int ret;
4161
4162 if (uss_ptr) {
4163 compat_stack_t uss32;
4164 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4165 return -EFAULT;
4166 uss.ss_sp = compat_ptr(uss32.ss_sp);
4167 uss.ss_flags = uss32.ss_flags;
4168 uss.ss_size = uss32.ss_size;
4169 }
4170 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4171 compat_user_stack_pointer(),
4172 COMPAT_MINSIGSTKSZ);
4173 if (ret >= 0 && uoss_ptr) {
4174 compat_stack_t old;
4175 memset(&old, 0, sizeof(old));
4176 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4177 old.ss_flags = uoss.ss_flags;
4178 old.ss_size = uoss.ss_size;
4179 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4180 ret = -EFAULT;
4181 }
4182 return ret;
4183}
4184
4185COMPAT_SYSCALL_DEFINE2(sigaltstack,
4186 const compat_stack_t __user *, uss_ptr,
4187 compat_stack_t __user *, uoss_ptr)
4188{
4189 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4190}
4191
4192int compat_restore_altstack(const compat_stack_t __user *uss)
4193{
4194 int err = do_compat_sigaltstack(uss, NULL);
4195 /* squash all but -EFAULT for now */
4196 return err == -EFAULT ? err : 0;
4197}
4198
4199int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4200{
4201 int err;
4202 struct task_struct *t = current;
4203 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4204 &uss->ss_sp) |
4205 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4206 __put_user(t->sas_ss_size, &uss->ss_size);
4207 return err;
4208}
4209#endif
4210
4211#ifdef __ARCH_WANT_SYS_SIGPENDING
4212
4213/**
4214 * sys_sigpending - examine pending signals
4215 * @uset: where mask of pending signal is returned
4216 */
4217SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4218{
4219 sigset_t set;
4220
4221 if (sizeof(old_sigset_t) > sizeof(*uset))
4222 return -EINVAL;
4223
4224 do_sigpending(&set);
4225
4226 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4227 return -EFAULT;
4228
4229 return 0;
4230}
4231
4232#ifdef CONFIG_COMPAT
4233COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4234{
4235 sigset_t set;
4236
4237 do_sigpending(&set);
4238
4239 return put_user(set.sig[0], set32);
4240}
4241#endif
4242
4243#endif
4244
4245#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4246/**
4247 * sys_sigprocmask - examine and change blocked signals
4248 * @how: whether to add, remove, or set signals
4249 * @nset: signals to add or remove (if non-null)
4250 * @oset: previous value of signal mask if non-null
4251 *
4252 * Some platforms have their own version with special arguments;
4253 * others support only sys_rt_sigprocmask.
4254 */
4255
4256SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4257 old_sigset_t __user *, oset)
4258{
4259 old_sigset_t old_set, new_set;
4260 sigset_t new_blocked;
4261
4262 old_set = current->blocked.sig[0];
4263
4264 if (nset) {
4265 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4266 return -EFAULT;
4267
4268 new_blocked = current->blocked;
4269
4270 switch (how) {
4271 case SIG_BLOCK:
4272 sigaddsetmask(&new_blocked, new_set);
4273 break;
4274 case SIG_UNBLOCK:
4275 sigdelsetmask(&new_blocked, new_set);
4276 break;
4277 case SIG_SETMASK:
4278 new_blocked.sig[0] = new_set;
4279 break;
4280 default:
4281 return -EINVAL;
4282 }
4283
4284 set_current_blocked(&new_blocked);
4285 }
4286
4287 if (oset) {
4288 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4289 return -EFAULT;
4290 }
4291
4292 return 0;
4293}
4294#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4295
4296#ifndef CONFIG_ODD_RT_SIGACTION
4297/**
4298 * sys_rt_sigaction - alter an action taken by a process
4299 * @sig: signal to be sent
4300 * @act: new sigaction
4301 * @oact: used to save the previous sigaction
4302 * @sigsetsize: size of sigset_t type
4303 */
4304SYSCALL_DEFINE4(rt_sigaction, int, sig,
4305 const struct sigaction __user *, act,
4306 struct sigaction __user *, oact,
4307 size_t, sigsetsize)
4308{
4309 struct k_sigaction new_sa, old_sa;
4310 int ret;
4311
4312 /* XXX: Don't preclude handling different sized sigset_t's. */
4313 if (sigsetsize != sizeof(sigset_t))
4314 return -EINVAL;
4315
4316 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4317 return -EFAULT;
4318
4319 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4320 if (ret)
4321 return ret;
4322
4323 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4324 return -EFAULT;
4325
4326 return 0;
4327}
4328#ifdef CONFIG_COMPAT
4329COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4330 const struct compat_sigaction __user *, act,
4331 struct compat_sigaction __user *, oact,
4332 compat_size_t, sigsetsize)
4333{
4334 struct k_sigaction new_ka, old_ka;
4335#ifdef __ARCH_HAS_SA_RESTORER
4336 compat_uptr_t restorer;
4337#endif
4338 int ret;
4339
4340 /* XXX: Don't preclude handling different sized sigset_t's. */
4341 if (sigsetsize != sizeof(compat_sigset_t))
4342 return -EINVAL;
4343
4344 if (act) {
4345 compat_uptr_t handler;
4346 ret = get_user(handler, &act->sa_handler);
4347 new_ka.sa.sa_handler = compat_ptr(handler);
4348#ifdef __ARCH_HAS_SA_RESTORER
4349 ret |= get_user(restorer, &act->sa_restorer);
4350 new_ka.sa.sa_restorer = compat_ptr(restorer);
4351#endif
4352 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4353 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4354 if (ret)
4355 return -EFAULT;
4356 }
4357
4358 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4359 if (!ret && oact) {
4360 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4361 &oact->sa_handler);
4362 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4363 sizeof(oact->sa_mask));
4364 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4365#ifdef __ARCH_HAS_SA_RESTORER
4366 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4367 &oact->sa_restorer);
4368#endif
4369 }
4370 return ret;
4371}
4372#endif
4373#endif /* !CONFIG_ODD_RT_SIGACTION */
4374
4375#ifdef CONFIG_OLD_SIGACTION
4376SYSCALL_DEFINE3(sigaction, int, sig,
4377 const struct old_sigaction __user *, act,
4378 struct old_sigaction __user *, oact)
4379{
4380 struct k_sigaction new_ka, old_ka;
4381 int ret;
4382
4383 if (act) {
4384 old_sigset_t mask;
4385 if (!access_ok(act, sizeof(*act)) ||
4386 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4387 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4388 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4389 __get_user(mask, &act->sa_mask))
4390 return -EFAULT;
4391#ifdef __ARCH_HAS_KA_RESTORER
4392 new_ka.ka_restorer = NULL;
4393#endif
4394 siginitset(&new_ka.sa.sa_mask, mask);
4395 }
4396
4397 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4398
4399 if (!ret && oact) {
4400 if (!access_ok(oact, sizeof(*oact)) ||
4401 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4402 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4403 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4404 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4405 return -EFAULT;
4406 }
4407
4408 return ret;
4409}
4410#endif
4411#ifdef CONFIG_COMPAT_OLD_SIGACTION
4412COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4413 const struct compat_old_sigaction __user *, act,
4414 struct compat_old_sigaction __user *, oact)
4415{
4416 struct k_sigaction new_ka, old_ka;
4417 int ret;
4418 compat_old_sigset_t mask;
4419 compat_uptr_t handler, restorer;
4420
4421 if (act) {
4422 if (!access_ok(act, sizeof(*act)) ||
4423 __get_user(handler, &act->sa_handler) ||
4424 __get_user(restorer, &act->sa_restorer) ||
4425 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4426 __get_user(mask, &act->sa_mask))
4427 return -EFAULT;
4428
4429#ifdef __ARCH_HAS_KA_RESTORER
4430 new_ka.ka_restorer = NULL;
4431#endif
4432 new_ka.sa.sa_handler = compat_ptr(handler);
4433 new_ka.sa.sa_restorer = compat_ptr(restorer);
4434 siginitset(&new_ka.sa.sa_mask, mask);
4435 }
4436
4437 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4438
4439 if (!ret && oact) {
4440 if (!access_ok(oact, sizeof(*oact)) ||
4441 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4442 &oact->sa_handler) ||
4443 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4444 &oact->sa_restorer) ||
4445 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4446 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4447 return -EFAULT;
4448 }
4449 return ret;
4450}
4451#endif
4452
4453#ifdef CONFIG_SGETMASK_SYSCALL
4454
4455/*
4456 * For backwards compatibility. Functionality superseded by sigprocmask.
4457 */
4458SYSCALL_DEFINE0(sgetmask)
4459{
4460 /* SMP safe */
4461 return current->blocked.sig[0];
4462}
4463
4464SYSCALL_DEFINE1(ssetmask, int, newmask)
4465{
4466 int old = current->blocked.sig[0];
4467 sigset_t newset;
4468
4469 siginitset(&newset, newmask);
4470 set_current_blocked(&newset);
4471
4472 return old;
4473}
4474#endif /* CONFIG_SGETMASK_SYSCALL */
4475
4476#ifdef __ARCH_WANT_SYS_SIGNAL
4477/*
4478 * For backwards compatibility. Functionality superseded by sigaction.
4479 */
4480SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4481{
4482 struct k_sigaction new_sa, old_sa;
4483 int ret;
4484
4485 new_sa.sa.sa_handler = handler;
4486 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4487 sigemptyset(&new_sa.sa.sa_mask);
4488
4489 ret = do_sigaction(sig, &new_sa, &old_sa);
4490
4491 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4492}
4493#endif /* __ARCH_WANT_SYS_SIGNAL */
4494
4495#ifdef __ARCH_WANT_SYS_PAUSE
4496
4497SYSCALL_DEFINE0(pause)
4498{
4499 while (!signal_pending(current)) {
4500 __set_current_state(TASK_INTERRUPTIBLE);
4501 schedule();
4502 }
4503 return -ERESTARTNOHAND;
4504}
4505
4506#endif
4507
4508static int sigsuspend(sigset_t *set)
4509{
4510 current->saved_sigmask = current->blocked;
4511 set_current_blocked(set);
4512
4513 while (!signal_pending(current)) {
4514 __set_current_state(TASK_INTERRUPTIBLE);
4515 schedule();
4516 }
4517 set_restore_sigmask();
4518 return -ERESTARTNOHAND;
4519}
4520
4521/**
4522 * sys_rt_sigsuspend - replace the signal mask for a value with the
4523 * @unewset value until a signal is received
4524 * @unewset: new signal mask value
4525 * @sigsetsize: size of sigset_t type
4526 */
4527SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4528{
4529 sigset_t newset;
4530
4531 /* XXX: Don't preclude handling different sized sigset_t's. */
4532 if (sigsetsize != sizeof(sigset_t))
4533 return -EINVAL;
4534
4535 if (copy_from_user(&newset, unewset, sizeof(newset)))
4536 return -EFAULT;
4537 return sigsuspend(&newset);
4538}
4539
4540#ifdef CONFIG_COMPAT
4541COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4542{
4543 sigset_t newset;
4544
4545 /* XXX: Don't preclude handling different sized sigset_t's. */
4546 if (sigsetsize != sizeof(sigset_t))
4547 return -EINVAL;
4548
4549 if (get_compat_sigset(&newset, unewset))
4550 return -EFAULT;
4551 return sigsuspend(&newset);
4552}
4553#endif
4554
4555#ifdef CONFIG_OLD_SIGSUSPEND
4556SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4557{
4558 sigset_t blocked;
4559 siginitset(&blocked, mask);
4560 return sigsuspend(&blocked);
4561}
4562#endif
4563#ifdef CONFIG_OLD_SIGSUSPEND3
4564SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4565{
4566 sigset_t blocked;
4567 siginitset(&blocked, mask);
4568 return sigsuspend(&blocked);
4569}
4570#endif
4571
4572__weak const char *arch_vma_name(struct vm_area_struct *vma)
4573{
4574 return NULL;
4575}
4576
4577static inline void siginfo_buildtime_checks(void)
4578{
4579 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4580
4581 /* Verify the offsets in the two siginfos match */
4582#define CHECK_OFFSET(field) \
4583 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4584
4585 /* kill */
4586 CHECK_OFFSET(si_pid);
4587 CHECK_OFFSET(si_uid);
4588
4589 /* timer */
4590 CHECK_OFFSET(si_tid);
4591 CHECK_OFFSET(si_overrun);
4592 CHECK_OFFSET(si_value);
4593
4594 /* rt */
4595 CHECK_OFFSET(si_pid);
4596 CHECK_OFFSET(si_uid);
4597 CHECK_OFFSET(si_value);
4598
4599 /* sigchld */
4600 CHECK_OFFSET(si_pid);
4601 CHECK_OFFSET(si_uid);
4602 CHECK_OFFSET(si_status);
4603 CHECK_OFFSET(si_utime);
4604 CHECK_OFFSET(si_stime);
4605
4606 /* sigfault */
4607 CHECK_OFFSET(si_addr);
4608 CHECK_OFFSET(si_trapno);
4609 CHECK_OFFSET(si_addr_lsb);
4610 CHECK_OFFSET(si_lower);
4611 CHECK_OFFSET(si_upper);
4612 CHECK_OFFSET(si_pkey);
4613 CHECK_OFFSET(si_perf_data);
4614 CHECK_OFFSET(si_perf_type);
4615
4616 /* sigpoll */
4617 CHECK_OFFSET(si_band);
4618 CHECK_OFFSET(si_fd);
4619
4620 /* sigsys */
4621 CHECK_OFFSET(si_call_addr);
4622 CHECK_OFFSET(si_syscall);
4623 CHECK_OFFSET(si_arch);
4624#undef CHECK_OFFSET
4625
4626 /* usb asyncio */
4627 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4628 offsetof(struct siginfo, si_addr));
4629 if (sizeof(int) == sizeof(void __user *)) {
4630 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4631 sizeof(void __user *));
4632 } else {
4633 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4634 sizeof_field(struct siginfo, si_uid)) !=
4635 sizeof(void __user *));
4636 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4637 offsetof(struct siginfo, si_uid));
4638 }
4639#ifdef CONFIG_COMPAT
4640 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4641 offsetof(struct compat_siginfo, si_addr));
4642 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4643 sizeof(compat_uptr_t));
4644 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4645 sizeof_field(struct siginfo, si_pid));
4646#endif
4647}
4648
4649void __init signals_init(void)
4650{
4651 siginfo_buildtime_checks();
4652
4653 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4654}
4655
4656#ifdef CONFIG_KGDB_KDB
4657#include <linux/kdb.h>
4658/*
4659 * kdb_send_sig - Allows kdb to send signals without exposing
4660 * signal internals. This function checks if the required locks are
4661 * available before calling the main signal code, to avoid kdb
4662 * deadlocks.
4663 */
4664void kdb_send_sig(struct task_struct *t, int sig)
4665{
4666 static struct task_struct *kdb_prev_t;
4667 int new_t, ret;
4668 if (!spin_trylock(&t->sighand->siglock)) {
4669 kdb_printf("Can't do kill command now.\n"
4670 "The sigmask lock is held somewhere else in "
4671 "kernel, try again later\n");
4672 return;
4673 }
4674 new_t = kdb_prev_t != t;
4675 kdb_prev_t = t;
4676 if (!task_is_running(t) && new_t) {
4677 spin_unlock(&t->sighand->siglock);
4678 kdb_printf("Process is not RUNNING, sending a signal from "
4679 "kdb risks deadlock\n"
4680 "on the run queue locks. "
4681 "The signal has _not_ been sent.\n"
4682 "Reissue the kill command if you want to risk "
4683 "the deadlock.\n");
4684 return;
4685 }
4686 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4687 spin_unlock(&t->sighand->siglock);
4688 if (ret)
4689 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4690 sig, t->pid);
4691 else
4692 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4693}
4694#endif /* CONFIG_KGDB_KDB */