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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/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/coredump.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/ptrace.h>
24#include <linux/signal.h>
25#include <linux/signalfd.h>
26#include <linux/ratelimit.h>
27#include <linux/tracehook.h>
28#include <linux/capability.h>
29#include <linux/freezer.h>
30#include <linux/pid_namespace.h>
31#include <linux/nsproxy.h>
32#include <linux/user_namespace.h>
33#include <linux/uprobes.h>
34#include <linux/compat.h>
35#include <linux/cn_proc.h>
36#include <linux/compiler.h>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <asm/uaccess.h>
43#include <asm/unistd.h>
44#include <asm/siginfo.h>
45#include <asm/cacheflush.h>
46#include "audit.h" /* audit_signal_info() */
47
48/*
49 * SLAB caches for signal bits.
50 */
51
52static struct kmem_cache *sigqueue_cachep;
53
54int print_fatal_signals __read_mostly;
55
56static void __user *sig_handler(struct task_struct *t, int sig)
57{
58 return t->sighand->action[sig - 1].sa.sa_handler;
59}
60
61static int sig_handler_ignored(void __user *handler, int sig)
62{
63 /* Is it explicitly or implicitly ignored? */
64 return handler == SIG_IGN ||
65 (handler == SIG_DFL && sig_kernel_ignore(sig));
66}
67
68static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69{
70 void __user *handler;
71
72 handler = sig_handler(t, sig);
73
74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 handler == SIG_DFL && !force)
76 return 1;
77
78 return sig_handler_ignored(handler, sig);
79}
80
81static int sig_ignored(struct task_struct *t, int sig, bool force)
82{
83 /*
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
86 * unblocked.
87 */
88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 return 0;
90
91 if (!sig_task_ignored(t, sig, force))
92 return 0;
93
94 /*
95 * Tracers may want to know about even ignored signals.
96 */
97 return !t->ptrace;
98}
99
100/*
101 * Re-calculate pending state from the set of locally pending
102 * signals, globally pending signals, and blocked signals.
103 */
104static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105{
106 unsigned long ready;
107 long i;
108
109 switch (_NSIG_WORDS) {
110 default:
111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 ready |= signal->sig[i] &~ blocked->sig[i];
113 break;
114
115 case 4: ready = signal->sig[3] &~ blocked->sig[3];
116 ready |= signal->sig[2] &~ blocked->sig[2];
117 ready |= signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
119 break;
120
121 case 2: ready = signal->sig[1] &~ blocked->sig[1];
122 ready |= signal->sig[0] &~ blocked->sig[0];
123 break;
124
125 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 }
127 return ready != 0;
128}
129
130#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131
132static int recalc_sigpending_tsk(struct task_struct *t)
133{
134 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 PENDING(&t->pending, &t->blocked) ||
136 PENDING(&t->signal->shared_pending, &t->blocked)) {
137 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 return 1;
139 }
140 /*
141 * We must never clear the flag in another thread, or in current
142 * when it's possible the current syscall is returning -ERESTART*.
143 * So we don't clear it here, and only callers who know they should do.
144 */
145 return 0;
146}
147
148/*
149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150 * This is superfluous when called on current, the wakeup is a harmless no-op.
151 */
152void recalc_sigpending_and_wake(struct task_struct *t)
153{
154 if (recalc_sigpending_tsk(t))
155 signal_wake_up(t, 0);
156}
157
158void recalc_sigpending(void)
159{
160 if (!recalc_sigpending_tsk(current) && !freezing(current))
161 clear_thread_flag(TIF_SIGPENDING);
162
163}
164
165/* Given the mask, find the first available signal that should be serviced. */
166
167#define SYNCHRONOUS_MASK \
168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170
171int next_signal(struct sigpending *pending, sigset_t *mask)
172{
173 unsigned long i, *s, *m, x;
174 int sig = 0;
175
176 s = pending->signal.sig;
177 m = mask->sig;
178
179 /*
180 * Handle the first word specially: it contains the
181 * synchronous signals that need to be dequeued first.
182 */
183 x = *s &~ *m;
184 if (x) {
185 if (x & SYNCHRONOUS_MASK)
186 x &= SYNCHRONOUS_MASK;
187 sig = ffz(~x) + 1;
188 return sig;
189 }
190
191 switch (_NSIG_WORDS) {
192 default:
193 for (i = 1; i < _NSIG_WORDS; ++i) {
194 x = *++s &~ *++m;
195 if (!x)
196 continue;
197 sig = ffz(~x) + i*_NSIG_BPW + 1;
198 break;
199 }
200 break;
201
202 case 2:
203 x = s[1] &~ m[1];
204 if (!x)
205 break;
206 sig = ffz(~x) + _NSIG_BPW + 1;
207 break;
208
209 case 1:
210 /* Nothing to do */
211 break;
212 }
213
214 return sig;
215}
216
217static inline void print_dropped_signal(int sig)
218{
219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220
221 if (!print_fatal_signals)
222 return;
223
224 if (!__ratelimit(&ratelimit_state))
225 return;
226
227 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 current->comm, current->pid, sig);
229}
230
231/**
232 * task_set_jobctl_pending - set jobctl pending bits
233 * @task: target task
234 * @mask: pending bits to set
235 *
236 * Clear @mask from @task->jobctl. @mask must be subset of
237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
239 * cleared. If @task is already being killed or exiting, this function
240 * becomes noop.
241 *
242 * CONTEXT:
243 * Must be called with @task->sighand->siglock held.
244 *
245 * RETURNS:
246 * %true if @mask is set, %false if made noop because @task was dying.
247 */
248bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
249{
250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253
254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 return false;
256
257 if (mask & JOBCTL_STOP_SIGMASK)
258 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259
260 task->jobctl |= mask;
261 return true;
262}
263
264/**
265 * task_clear_jobctl_trapping - clear jobctl trapping bit
266 * @task: target task
267 *
268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269 * Clear it and wake up the ptracer. Note that we don't need any further
270 * locking. @task->siglock guarantees that @task->parent points to the
271 * ptracer.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 */
276void task_clear_jobctl_trapping(struct task_struct *task)
277{
278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 task->jobctl &= ~JOBCTL_TRAPPING;
280 smp_mb(); /* advised by wake_up_bit() */
281 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
282 }
283}
284
285/**
286 * task_clear_jobctl_pending - clear jobctl pending bits
287 * @task: target task
288 * @mask: pending bits to clear
289 *
290 * Clear @mask from @task->jobctl. @mask must be subset of
291 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
292 * STOP bits are cleared together.
293 *
294 * If clearing of @mask leaves no stop or trap pending, this function calls
295 * task_clear_jobctl_trapping().
296 *
297 * CONTEXT:
298 * Must be called with @task->sighand->siglock held.
299 */
300void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
301{
302 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
303
304 if (mask & JOBCTL_STOP_PENDING)
305 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
306
307 task->jobctl &= ~mask;
308
309 if (!(task->jobctl & JOBCTL_PENDING_MASK))
310 task_clear_jobctl_trapping(task);
311}
312
313/**
314 * task_participate_group_stop - participate in a group stop
315 * @task: task participating in a group stop
316 *
317 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
318 * Group stop states are cleared and the group stop count is consumed if
319 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
320 * stop, the appropriate %SIGNAL_* flags are set.
321 *
322 * CONTEXT:
323 * Must be called with @task->sighand->siglock held.
324 *
325 * RETURNS:
326 * %true if group stop completion should be notified to the parent, %false
327 * otherwise.
328 */
329static bool task_participate_group_stop(struct task_struct *task)
330{
331 struct signal_struct *sig = task->signal;
332 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
333
334 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
335
336 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
337
338 if (!consume)
339 return false;
340
341 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
342 sig->group_stop_count--;
343
344 /*
345 * Tell the caller to notify completion iff we are entering into a
346 * fresh group stop. Read comment in do_signal_stop() for details.
347 */
348 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
349 sig->flags = SIGNAL_STOP_STOPPED;
350 return true;
351 }
352 return false;
353}
354
355/*
356 * allocate a new signal queue record
357 * - this may be called without locks if and only if t == current, otherwise an
358 * appropriate lock must be held to stop the target task from exiting
359 */
360static struct sigqueue *
361__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
362{
363 struct sigqueue *q = NULL;
364 struct user_struct *user;
365
366 /*
367 * Protect access to @t credentials. This can go away when all
368 * callers hold rcu read lock.
369 */
370 rcu_read_lock();
371 user = get_uid(__task_cred(t)->user);
372 atomic_inc(&user->sigpending);
373 rcu_read_unlock();
374
375 if (override_rlimit ||
376 atomic_read(&user->sigpending) <=
377 task_rlimit(t, RLIMIT_SIGPENDING)) {
378 q = kmem_cache_alloc(sigqueue_cachep, flags);
379 } else {
380 print_dropped_signal(sig);
381 }
382
383 if (unlikely(q == NULL)) {
384 atomic_dec(&user->sigpending);
385 free_uid(user);
386 } else {
387 INIT_LIST_HEAD(&q->list);
388 q->flags = 0;
389 q->user = user;
390 }
391
392 return q;
393}
394
395static void __sigqueue_free(struct sigqueue *q)
396{
397 if (q->flags & SIGQUEUE_PREALLOC)
398 return;
399 atomic_dec(&q->user->sigpending);
400 free_uid(q->user);
401 kmem_cache_free(sigqueue_cachep, q);
402}
403
404void flush_sigqueue(struct sigpending *queue)
405{
406 struct sigqueue *q;
407
408 sigemptyset(&queue->signal);
409 while (!list_empty(&queue->list)) {
410 q = list_entry(queue->list.next, struct sigqueue , list);
411 list_del_init(&q->list);
412 __sigqueue_free(q);
413 }
414}
415
416/*
417 * Flush all pending signals for this kthread.
418 */
419void flush_signals(struct task_struct *t)
420{
421 unsigned long flags;
422
423 spin_lock_irqsave(&t->sighand->siglock, flags);
424 clear_tsk_thread_flag(t, TIF_SIGPENDING);
425 flush_sigqueue(&t->pending);
426 flush_sigqueue(&t->signal->shared_pending);
427 spin_unlock_irqrestore(&t->sighand->siglock, flags);
428}
429
430static void __flush_itimer_signals(struct sigpending *pending)
431{
432 sigset_t signal, retain;
433 struct sigqueue *q, *n;
434
435 signal = pending->signal;
436 sigemptyset(&retain);
437
438 list_for_each_entry_safe(q, n, &pending->list, list) {
439 int sig = q->info.si_signo;
440
441 if (likely(q->info.si_code != SI_TIMER)) {
442 sigaddset(&retain, sig);
443 } else {
444 sigdelset(&signal, sig);
445 list_del_init(&q->list);
446 __sigqueue_free(q);
447 }
448 }
449
450 sigorsets(&pending->signal, &signal, &retain);
451}
452
453void flush_itimer_signals(void)
454{
455 struct task_struct *tsk = current;
456 unsigned long flags;
457
458 spin_lock_irqsave(&tsk->sighand->siglock, flags);
459 __flush_itimer_signals(&tsk->pending);
460 __flush_itimer_signals(&tsk->signal->shared_pending);
461 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
462}
463
464void ignore_signals(struct task_struct *t)
465{
466 int i;
467
468 for (i = 0; i < _NSIG; ++i)
469 t->sighand->action[i].sa.sa_handler = SIG_IGN;
470
471 flush_signals(t);
472}
473
474/*
475 * Flush all handlers for a task.
476 */
477
478void
479flush_signal_handlers(struct task_struct *t, int force_default)
480{
481 int i;
482 struct k_sigaction *ka = &t->sighand->action[0];
483 for (i = _NSIG ; i != 0 ; i--) {
484 if (force_default || ka->sa.sa_handler != SIG_IGN)
485 ka->sa.sa_handler = SIG_DFL;
486 ka->sa.sa_flags = 0;
487#ifdef __ARCH_HAS_SA_RESTORER
488 ka->sa.sa_restorer = NULL;
489#endif
490 sigemptyset(&ka->sa.sa_mask);
491 ka++;
492 }
493}
494
495int unhandled_signal(struct task_struct *tsk, int sig)
496{
497 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
498 if (is_global_init(tsk))
499 return 1;
500 if (handler != SIG_IGN && handler != SIG_DFL)
501 return 0;
502 /* if ptraced, let the tracer determine */
503 return !tsk->ptrace;
504}
505
506static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
507{
508 struct sigqueue *q, *first = NULL;
509
510 /*
511 * Collect the siginfo appropriate to this signal. Check if
512 * there is another siginfo for the same signal.
513 */
514 list_for_each_entry(q, &list->list, list) {
515 if (q->info.si_signo == sig) {
516 if (first)
517 goto still_pending;
518 first = q;
519 }
520 }
521
522 sigdelset(&list->signal, sig);
523
524 if (first) {
525still_pending:
526 list_del_init(&first->list);
527 copy_siginfo(info, &first->info);
528 __sigqueue_free(first);
529 } else {
530 /*
531 * Ok, it wasn't in the queue. This must be
532 * a fast-pathed signal or we must have been
533 * out of queue space. So zero out the info.
534 */
535 info->si_signo = sig;
536 info->si_errno = 0;
537 info->si_code = SI_USER;
538 info->si_pid = 0;
539 info->si_uid = 0;
540 }
541}
542
543static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
544 siginfo_t *info)
545{
546 int sig = next_signal(pending, mask);
547
548 if (sig)
549 collect_signal(sig, pending, info);
550 return sig;
551}
552
553/*
554 * Dequeue a signal and return the element to the caller, which is
555 * expected to free it.
556 *
557 * All callers have to hold the siglock.
558 */
559int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
560{
561 int signr;
562
563 /* We only dequeue private signals from ourselves, we don't let
564 * signalfd steal them
565 */
566 signr = __dequeue_signal(&tsk->pending, mask, info);
567 if (!signr) {
568 signr = __dequeue_signal(&tsk->signal->shared_pending,
569 mask, info);
570 /*
571 * itimer signal ?
572 *
573 * itimers are process shared and we restart periodic
574 * itimers in the signal delivery path to prevent DoS
575 * attacks in the high resolution timer case. This is
576 * compliant with the old way of self-restarting
577 * itimers, as the SIGALRM is a legacy signal and only
578 * queued once. Changing the restart behaviour to
579 * restart the timer in the signal dequeue path is
580 * reducing the timer noise on heavy loaded !highres
581 * systems too.
582 */
583 if (unlikely(signr == SIGALRM)) {
584 struct hrtimer *tmr = &tsk->signal->real_timer;
585
586 if (!hrtimer_is_queued(tmr) &&
587 tsk->signal->it_real_incr.tv64 != 0) {
588 hrtimer_forward(tmr, tmr->base->get_time(),
589 tsk->signal->it_real_incr);
590 hrtimer_restart(tmr);
591 }
592 }
593 }
594
595 recalc_sigpending();
596 if (!signr)
597 return 0;
598
599 if (unlikely(sig_kernel_stop(signr))) {
600 /*
601 * Set a marker that we have dequeued a stop signal. Our
602 * caller might release the siglock and then the pending
603 * stop signal it is about to process is no longer in the
604 * pending bitmasks, but must still be cleared by a SIGCONT
605 * (and overruled by a SIGKILL). So those cases clear this
606 * shared flag after we've set it. Note that this flag may
607 * remain set after the signal we return is ignored or
608 * handled. That doesn't matter because its only purpose
609 * is to alert stop-signal processing code when another
610 * processor has come along and cleared the flag.
611 */
612 current->jobctl |= JOBCTL_STOP_DEQUEUED;
613 }
614 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
615 /*
616 * Release the siglock to ensure proper locking order
617 * of timer locks outside of siglocks. Note, we leave
618 * irqs disabled here, since the posix-timers code is
619 * about to disable them again anyway.
620 */
621 spin_unlock(&tsk->sighand->siglock);
622 do_schedule_next_timer(info);
623 spin_lock(&tsk->sighand->siglock);
624 }
625 return signr;
626}
627
628/*
629 * Tell a process that it has a new active signal..
630 *
631 * NOTE! we rely on the previous spin_lock to
632 * lock interrupts for us! We can only be called with
633 * "siglock" held, and the local interrupt must
634 * have been disabled when that got acquired!
635 *
636 * No need to set need_resched since signal event passing
637 * goes through ->blocked
638 */
639void signal_wake_up_state(struct task_struct *t, unsigned int state)
640{
641 set_tsk_thread_flag(t, TIF_SIGPENDING);
642 /*
643 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
644 * case. We don't check t->state here because there is a race with it
645 * executing another processor and just now entering stopped state.
646 * By using wake_up_state, we ensure the process will wake up and
647 * handle its death signal.
648 */
649 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
650 kick_process(t);
651}
652
653/*
654 * Remove signals in mask from the pending set and queue.
655 * Returns 1 if any signals were found.
656 *
657 * All callers must be holding the siglock.
658 */
659static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
660{
661 struct sigqueue *q, *n;
662 sigset_t m;
663
664 sigandsets(&m, mask, &s->signal);
665 if (sigisemptyset(&m))
666 return 0;
667
668 sigandnsets(&s->signal, &s->signal, mask);
669 list_for_each_entry_safe(q, n, &s->list, list) {
670 if (sigismember(mask, q->info.si_signo)) {
671 list_del_init(&q->list);
672 __sigqueue_free(q);
673 }
674 }
675 return 1;
676}
677
678static inline int is_si_special(const struct siginfo *info)
679{
680 return info <= SEND_SIG_FORCED;
681}
682
683static inline bool si_fromuser(const struct siginfo *info)
684{
685 return info == SEND_SIG_NOINFO ||
686 (!is_si_special(info) && SI_FROMUSER(info));
687}
688
689/*
690 * called with RCU read lock from check_kill_permission()
691 */
692static int kill_ok_by_cred(struct task_struct *t)
693{
694 const struct cred *cred = current_cred();
695 const struct cred *tcred = __task_cred(t);
696
697 if (uid_eq(cred->euid, tcred->suid) ||
698 uid_eq(cred->euid, tcred->uid) ||
699 uid_eq(cred->uid, tcred->suid) ||
700 uid_eq(cred->uid, tcred->uid))
701 return 1;
702
703 if (ns_capable(tcred->user_ns, CAP_KILL))
704 return 1;
705
706 return 0;
707}
708
709/*
710 * Bad permissions for sending the signal
711 * - the caller must hold the RCU read lock
712 */
713static int check_kill_permission(int sig, struct siginfo *info,
714 struct task_struct *t)
715{
716 struct pid *sid;
717 int error;
718
719 if (!valid_signal(sig))
720 return -EINVAL;
721
722 if (!si_fromuser(info))
723 return 0;
724
725 error = audit_signal_info(sig, t); /* Let audit system see the signal */
726 if (error)
727 return error;
728
729 if (!same_thread_group(current, t) &&
730 !kill_ok_by_cred(t)) {
731 switch (sig) {
732 case SIGCONT:
733 sid = task_session(t);
734 /*
735 * We don't return the error if sid == NULL. The
736 * task was unhashed, the caller must notice this.
737 */
738 if (!sid || sid == task_session(current))
739 break;
740 default:
741 return -EPERM;
742 }
743 }
744
745 return security_task_kill(t, info, sig, 0);
746}
747
748/**
749 * ptrace_trap_notify - schedule trap to notify ptracer
750 * @t: tracee wanting to notify tracer
751 *
752 * This function schedules sticky ptrace trap which is cleared on the next
753 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
754 * ptracer.
755 *
756 * If @t is running, STOP trap will be taken. If trapped for STOP and
757 * ptracer is listening for events, tracee is woken up so that it can
758 * re-trap for the new event. If trapped otherwise, STOP trap will be
759 * eventually taken without returning to userland after the existing traps
760 * are finished by PTRACE_CONT.
761 *
762 * CONTEXT:
763 * Must be called with @task->sighand->siglock held.
764 */
765static void ptrace_trap_notify(struct task_struct *t)
766{
767 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
768 assert_spin_locked(&t->sighand->siglock);
769
770 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
771 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
772}
773
774/*
775 * Handle magic process-wide effects of stop/continue signals. Unlike
776 * the signal actions, these happen immediately at signal-generation
777 * time regardless of blocking, ignoring, or handling. This does the
778 * actual continuing for SIGCONT, but not the actual stopping for stop
779 * signals. The process stop is done as a signal action for SIG_DFL.
780 *
781 * Returns true if the signal should be actually delivered, otherwise
782 * it should be dropped.
783 */
784static bool prepare_signal(int sig, struct task_struct *p, bool force)
785{
786 struct signal_struct *signal = p->signal;
787 struct task_struct *t;
788 sigset_t flush;
789
790 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
791 if (!(signal->flags & SIGNAL_GROUP_EXIT))
792 return sig == SIGKILL;
793 /*
794 * The process is in the middle of dying, nothing to do.
795 */
796 } else if (sig_kernel_stop(sig)) {
797 /*
798 * This is a stop signal. Remove SIGCONT from all queues.
799 */
800 siginitset(&flush, sigmask(SIGCONT));
801 flush_sigqueue_mask(&flush, &signal->shared_pending);
802 for_each_thread(p, t)
803 flush_sigqueue_mask(&flush, &t->pending);
804 } else if (sig == SIGCONT) {
805 unsigned int why;
806 /*
807 * Remove all stop signals from all queues, wake all threads.
808 */
809 siginitset(&flush, SIG_KERNEL_STOP_MASK);
810 flush_sigqueue_mask(&flush, &signal->shared_pending);
811 for_each_thread(p, t) {
812 flush_sigqueue_mask(&flush, &t->pending);
813 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
814 if (likely(!(t->ptrace & PT_SEIZED)))
815 wake_up_state(t, __TASK_STOPPED);
816 else
817 ptrace_trap_notify(t);
818 }
819
820 /*
821 * Notify the parent with CLD_CONTINUED if we were stopped.
822 *
823 * If we were in the middle of a group stop, we pretend it
824 * was already finished, and then continued. Since SIGCHLD
825 * doesn't queue we report only CLD_STOPPED, as if the next
826 * CLD_CONTINUED was dropped.
827 */
828 why = 0;
829 if (signal->flags & SIGNAL_STOP_STOPPED)
830 why |= SIGNAL_CLD_CONTINUED;
831 else if (signal->group_stop_count)
832 why |= SIGNAL_CLD_STOPPED;
833
834 if (why) {
835 /*
836 * The first thread which returns from do_signal_stop()
837 * will take ->siglock, notice SIGNAL_CLD_MASK, and
838 * notify its parent. See get_signal_to_deliver().
839 */
840 signal->flags = why | SIGNAL_STOP_CONTINUED;
841 signal->group_stop_count = 0;
842 signal->group_exit_code = 0;
843 }
844 }
845
846 return !sig_ignored(p, sig, force);
847}
848
849/*
850 * Test if P wants to take SIG. After we've checked all threads with this,
851 * it's equivalent to finding no threads not blocking SIG. Any threads not
852 * blocking SIG were ruled out because they are not running and already
853 * have pending signals. Such threads will dequeue from the shared queue
854 * as soon as they're available, so putting the signal on the shared queue
855 * will be equivalent to sending it to one such thread.
856 */
857static inline int wants_signal(int sig, struct task_struct *p)
858{
859 if (sigismember(&p->blocked, sig))
860 return 0;
861 if (p->flags & PF_EXITING)
862 return 0;
863 if (sig == SIGKILL)
864 return 1;
865 if (task_is_stopped_or_traced(p))
866 return 0;
867 return task_curr(p) || !signal_pending(p);
868}
869
870static void complete_signal(int sig, struct task_struct *p, int group)
871{
872 struct signal_struct *signal = p->signal;
873 struct task_struct *t;
874
875 /*
876 * Now find a thread we can wake up to take the signal off the queue.
877 *
878 * If the main thread wants the signal, it gets first crack.
879 * Probably the least surprising to the average bear.
880 */
881 if (wants_signal(sig, p))
882 t = p;
883 else if (!group || thread_group_empty(p))
884 /*
885 * There is just one thread and it does not need to be woken.
886 * It will dequeue unblocked signals before it runs again.
887 */
888 return;
889 else {
890 /*
891 * Otherwise try to find a suitable thread.
892 */
893 t = signal->curr_target;
894 while (!wants_signal(sig, t)) {
895 t = next_thread(t);
896 if (t == signal->curr_target)
897 /*
898 * No thread needs to be woken.
899 * Any eligible threads will see
900 * the signal in the queue soon.
901 */
902 return;
903 }
904 signal->curr_target = t;
905 }
906
907 /*
908 * Found a killable thread. If the signal will be fatal,
909 * then start taking the whole group down immediately.
910 */
911 if (sig_fatal(p, sig) &&
912 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
913 !sigismember(&t->real_blocked, sig) &&
914 (sig == SIGKILL || !t->ptrace)) {
915 /*
916 * This signal will be fatal to the whole group.
917 */
918 if (!sig_kernel_coredump(sig)) {
919 /*
920 * Start a group exit and wake everybody up.
921 * This way we don't have other threads
922 * running and doing things after a slower
923 * thread has the fatal signal pending.
924 */
925 signal->flags = SIGNAL_GROUP_EXIT;
926 signal->group_exit_code = sig;
927 signal->group_stop_count = 0;
928 t = p;
929 do {
930 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
931 sigaddset(&t->pending.signal, SIGKILL);
932 signal_wake_up(t, 1);
933 } while_each_thread(p, t);
934 return;
935 }
936 }
937
938 /*
939 * The signal is already in the shared-pending queue.
940 * Tell the chosen thread to wake up and dequeue it.
941 */
942 signal_wake_up(t, sig == SIGKILL);
943 return;
944}
945
946static inline int legacy_queue(struct sigpending *signals, int sig)
947{
948 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
949}
950
951#ifdef CONFIG_USER_NS
952static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
953{
954 if (current_user_ns() == task_cred_xxx(t, user_ns))
955 return;
956
957 if (SI_FROMKERNEL(info))
958 return;
959
960 rcu_read_lock();
961 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
962 make_kuid(current_user_ns(), info->si_uid));
963 rcu_read_unlock();
964}
965#else
966static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
967{
968 return;
969}
970#endif
971
972static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
973 int group, int from_ancestor_ns)
974{
975 struct sigpending *pending;
976 struct sigqueue *q;
977 int override_rlimit;
978 int ret = 0, result;
979
980 assert_spin_locked(&t->sighand->siglock);
981
982 result = TRACE_SIGNAL_IGNORED;
983 if (!prepare_signal(sig, t,
984 from_ancestor_ns || (info == SEND_SIG_FORCED)))
985 goto ret;
986
987 pending = group ? &t->signal->shared_pending : &t->pending;
988 /*
989 * Short-circuit ignored signals and support queuing
990 * exactly one non-rt signal, so that we can get more
991 * detailed information about the cause of the signal.
992 */
993 result = TRACE_SIGNAL_ALREADY_PENDING;
994 if (legacy_queue(pending, sig))
995 goto ret;
996
997 result = TRACE_SIGNAL_DELIVERED;
998 /*
999 * fast-pathed signals for kernel-internal things like SIGSTOP
1000 * or SIGKILL.
1001 */
1002 if (info == SEND_SIG_FORCED)
1003 goto out_set;
1004
1005 /*
1006 * Real-time signals must be queued if sent by sigqueue, or
1007 * some other real-time mechanism. It is implementation
1008 * defined whether kill() does so. We attempt to do so, on
1009 * the principle of least surprise, but since kill is not
1010 * allowed to fail with EAGAIN when low on memory we just
1011 * make sure at least one signal gets delivered and don't
1012 * pass on the info struct.
1013 */
1014 if (sig < SIGRTMIN)
1015 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1016 else
1017 override_rlimit = 0;
1018
1019 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1020 override_rlimit);
1021 if (q) {
1022 list_add_tail(&q->list, &pending->list);
1023 switch ((unsigned long) info) {
1024 case (unsigned long) SEND_SIG_NOINFO:
1025 q->info.si_signo = sig;
1026 q->info.si_errno = 0;
1027 q->info.si_code = SI_USER;
1028 q->info.si_pid = task_tgid_nr_ns(current,
1029 task_active_pid_ns(t));
1030 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1031 break;
1032 case (unsigned long) SEND_SIG_PRIV:
1033 q->info.si_signo = sig;
1034 q->info.si_errno = 0;
1035 q->info.si_code = SI_KERNEL;
1036 q->info.si_pid = 0;
1037 q->info.si_uid = 0;
1038 break;
1039 default:
1040 copy_siginfo(&q->info, info);
1041 if (from_ancestor_ns)
1042 q->info.si_pid = 0;
1043 break;
1044 }
1045
1046 userns_fixup_signal_uid(&q->info, t);
1047
1048 } else if (!is_si_special(info)) {
1049 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1050 /*
1051 * Queue overflow, abort. We may abort if the
1052 * signal was rt and sent by user using something
1053 * other than kill().
1054 */
1055 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1056 ret = -EAGAIN;
1057 goto ret;
1058 } else {
1059 /*
1060 * This is a silent loss of information. We still
1061 * send the signal, but the *info bits are lost.
1062 */
1063 result = TRACE_SIGNAL_LOSE_INFO;
1064 }
1065 }
1066
1067out_set:
1068 signalfd_notify(t, sig);
1069 sigaddset(&pending->signal, sig);
1070 complete_signal(sig, t, group);
1071ret:
1072 trace_signal_generate(sig, info, t, group, result);
1073 return ret;
1074}
1075
1076static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1077 int group)
1078{
1079 int from_ancestor_ns = 0;
1080
1081#ifdef CONFIG_PID_NS
1082 from_ancestor_ns = si_fromuser(info) &&
1083 !task_pid_nr_ns(current, task_active_pid_ns(t));
1084#endif
1085
1086 return __send_signal(sig, info, t, group, from_ancestor_ns);
1087}
1088
1089static void print_fatal_signal(int signr)
1090{
1091 struct pt_regs *regs = signal_pt_regs();
1092 printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1093
1094#if defined(__i386__) && !defined(__arch_um__)
1095 printk(KERN_INFO "code at %08lx: ", regs->ip);
1096 {
1097 int i;
1098 for (i = 0; i < 16; i++) {
1099 unsigned char insn;
1100
1101 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1102 break;
1103 printk(KERN_CONT "%02x ", insn);
1104 }
1105 }
1106 printk(KERN_CONT "\n");
1107#endif
1108 preempt_disable();
1109 show_regs(regs);
1110 preempt_enable();
1111}
1112
1113static int __init setup_print_fatal_signals(char *str)
1114{
1115 get_option (&str, &print_fatal_signals);
1116
1117 return 1;
1118}
1119
1120__setup("print-fatal-signals=", setup_print_fatal_signals);
1121
1122int
1123__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1124{
1125 return send_signal(sig, info, p, 1);
1126}
1127
1128static int
1129specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1130{
1131 return send_signal(sig, info, t, 0);
1132}
1133
1134int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1135 bool group)
1136{
1137 unsigned long flags;
1138 int ret = -ESRCH;
1139
1140 if (lock_task_sighand(p, &flags)) {
1141 ret = send_signal(sig, info, p, group);
1142 unlock_task_sighand(p, &flags);
1143 }
1144
1145 return ret;
1146}
1147
1148/*
1149 * Force a signal that the process can't ignore: if necessary
1150 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1151 *
1152 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1153 * since we do not want to have a signal handler that was blocked
1154 * be invoked when user space had explicitly blocked it.
1155 *
1156 * We don't want to have recursive SIGSEGV's etc, for example,
1157 * that is why we also clear SIGNAL_UNKILLABLE.
1158 */
1159int
1160force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1161{
1162 unsigned long int flags;
1163 int ret, blocked, ignored;
1164 struct k_sigaction *action;
1165
1166 spin_lock_irqsave(&t->sighand->siglock, flags);
1167 action = &t->sighand->action[sig-1];
1168 ignored = action->sa.sa_handler == SIG_IGN;
1169 blocked = sigismember(&t->blocked, sig);
1170 if (blocked || ignored) {
1171 action->sa.sa_handler = SIG_DFL;
1172 if (blocked) {
1173 sigdelset(&t->blocked, sig);
1174 recalc_sigpending_and_wake(t);
1175 }
1176 }
1177 if (action->sa.sa_handler == SIG_DFL)
1178 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1179 ret = specific_send_sig_info(sig, info, t);
1180 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1181
1182 return ret;
1183}
1184
1185/*
1186 * Nuke all other threads in the group.
1187 */
1188int zap_other_threads(struct task_struct *p)
1189{
1190 struct task_struct *t = p;
1191 int count = 0;
1192
1193 p->signal->group_stop_count = 0;
1194
1195 while_each_thread(p, t) {
1196 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1197 count++;
1198
1199 /* Don't bother with already dead threads */
1200 if (t->exit_state)
1201 continue;
1202 sigaddset(&t->pending.signal, SIGKILL);
1203 signal_wake_up(t, 1);
1204 }
1205
1206 return count;
1207}
1208
1209struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1210 unsigned long *flags)
1211{
1212 struct sighand_struct *sighand;
1213
1214 for (;;) {
1215 /*
1216 * Disable interrupts early to avoid deadlocks.
1217 * See rcu_read_unlock() comment header for details.
1218 */
1219 local_irq_save(*flags);
1220 rcu_read_lock();
1221 sighand = rcu_dereference(tsk->sighand);
1222 if (unlikely(sighand == NULL)) {
1223 rcu_read_unlock();
1224 local_irq_restore(*flags);
1225 break;
1226 }
1227 /*
1228 * This sighand can be already freed and even reused, but
1229 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1230 * initializes ->siglock: this slab can't go away, it has
1231 * the same object type, ->siglock can't be reinitialized.
1232 *
1233 * We need to ensure that tsk->sighand is still the same
1234 * after we take the lock, we can race with de_thread() or
1235 * __exit_signal(). In the latter case the next iteration
1236 * must see ->sighand == NULL.
1237 */
1238 spin_lock(&sighand->siglock);
1239 if (likely(sighand == tsk->sighand)) {
1240 rcu_read_unlock();
1241 break;
1242 }
1243 spin_unlock(&sighand->siglock);
1244 rcu_read_unlock();
1245 local_irq_restore(*flags);
1246 }
1247
1248 return sighand;
1249}
1250
1251/*
1252 * send signal info to all the members of a group
1253 */
1254int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1255{
1256 int ret;
1257
1258 rcu_read_lock();
1259 ret = check_kill_permission(sig, info, p);
1260 rcu_read_unlock();
1261
1262 if (!ret && sig)
1263 ret = do_send_sig_info(sig, info, p, true);
1264
1265 return ret;
1266}
1267
1268/*
1269 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1270 * control characters do (^C, ^Z etc)
1271 * - the caller must hold at least a readlock on tasklist_lock
1272 */
1273int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1274{
1275 struct task_struct *p = NULL;
1276 int retval, success;
1277
1278 success = 0;
1279 retval = -ESRCH;
1280 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1281 int err = group_send_sig_info(sig, info, p);
1282 success |= !err;
1283 retval = err;
1284 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1285 return success ? 0 : retval;
1286}
1287
1288int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1289{
1290 int error = -ESRCH;
1291 struct task_struct *p;
1292
1293 for (;;) {
1294 rcu_read_lock();
1295 p = pid_task(pid, PIDTYPE_PID);
1296 if (p)
1297 error = group_send_sig_info(sig, info, p);
1298 rcu_read_unlock();
1299 if (likely(!p || error != -ESRCH))
1300 return error;
1301
1302 /*
1303 * The task was unhashed in between, try again. If it
1304 * is dead, pid_task() will return NULL, if we race with
1305 * de_thread() it will find the new leader.
1306 */
1307 }
1308}
1309
1310int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1311{
1312 int error;
1313 rcu_read_lock();
1314 error = kill_pid_info(sig, info, find_vpid(pid));
1315 rcu_read_unlock();
1316 return error;
1317}
1318
1319static int kill_as_cred_perm(const struct cred *cred,
1320 struct task_struct *target)
1321{
1322 const struct cred *pcred = __task_cred(target);
1323 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1324 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1325 return 0;
1326 return 1;
1327}
1328
1329/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1330int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1331 const struct cred *cred, u32 secid)
1332{
1333 int ret = -EINVAL;
1334 struct task_struct *p;
1335 unsigned long flags;
1336
1337 if (!valid_signal(sig))
1338 return ret;
1339
1340 rcu_read_lock();
1341 p = pid_task(pid, PIDTYPE_PID);
1342 if (!p) {
1343 ret = -ESRCH;
1344 goto out_unlock;
1345 }
1346 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1347 ret = -EPERM;
1348 goto out_unlock;
1349 }
1350 ret = security_task_kill(p, info, sig, secid);
1351 if (ret)
1352 goto out_unlock;
1353
1354 if (sig) {
1355 if (lock_task_sighand(p, &flags)) {
1356 ret = __send_signal(sig, info, p, 1, 0);
1357 unlock_task_sighand(p, &flags);
1358 } else
1359 ret = -ESRCH;
1360 }
1361out_unlock:
1362 rcu_read_unlock();
1363 return ret;
1364}
1365EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1366
1367/*
1368 * kill_something_info() interprets pid in interesting ways just like kill(2).
1369 *
1370 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1371 * is probably wrong. Should make it like BSD or SYSV.
1372 */
1373
1374static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1375{
1376 int ret;
1377
1378 if (pid > 0) {
1379 rcu_read_lock();
1380 ret = kill_pid_info(sig, info, find_vpid(pid));
1381 rcu_read_unlock();
1382 return ret;
1383 }
1384
1385 read_lock(&tasklist_lock);
1386 if (pid != -1) {
1387 ret = __kill_pgrp_info(sig, info,
1388 pid ? find_vpid(-pid) : task_pgrp(current));
1389 } else {
1390 int retval = 0, count = 0;
1391 struct task_struct * p;
1392
1393 for_each_process(p) {
1394 if (task_pid_vnr(p) > 1 &&
1395 !same_thread_group(p, current)) {
1396 int err = group_send_sig_info(sig, info, p);
1397 ++count;
1398 if (err != -EPERM)
1399 retval = err;
1400 }
1401 }
1402 ret = count ? retval : -ESRCH;
1403 }
1404 read_unlock(&tasklist_lock);
1405
1406 return ret;
1407}
1408
1409/*
1410 * These are for backward compatibility with the rest of the kernel source.
1411 */
1412
1413int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1414{
1415 /*
1416 * Make sure legacy kernel users don't send in bad values
1417 * (normal paths check this in check_kill_permission).
1418 */
1419 if (!valid_signal(sig))
1420 return -EINVAL;
1421
1422 return do_send_sig_info(sig, info, p, false);
1423}
1424
1425#define __si_special(priv) \
1426 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1427
1428int
1429send_sig(int sig, struct task_struct *p, int priv)
1430{
1431 return send_sig_info(sig, __si_special(priv), p);
1432}
1433
1434void
1435force_sig(int sig, struct task_struct *p)
1436{
1437 force_sig_info(sig, SEND_SIG_PRIV, p);
1438}
1439
1440/*
1441 * When things go south during signal handling, we
1442 * will force a SIGSEGV. And if the signal that caused
1443 * the problem was already a SIGSEGV, we'll want to
1444 * make sure we don't even try to deliver the signal..
1445 */
1446int
1447force_sigsegv(int sig, struct task_struct *p)
1448{
1449 if (sig == SIGSEGV) {
1450 unsigned long flags;
1451 spin_lock_irqsave(&p->sighand->siglock, flags);
1452 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1453 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1454 }
1455 force_sig(SIGSEGV, p);
1456 return 0;
1457}
1458
1459int kill_pgrp(struct pid *pid, int sig, int priv)
1460{
1461 int ret;
1462
1463 read_lock(&tasklist_lock);
1464 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1465 read_unlock(&tasklist_lock);
1466
1467 return ret;
1468}
1469EXPORT_SYMBOL(kill_pgrp);
1470
1471int kill_pid(struct pid *pid, int sig, int priv)
1472{
1473 return kill_pid_info(sig, __si_special(priv), pid);
1474}
1475EXPORT_SYMBOL(kill_pid);
1476
1477/*
1478 * These functions support sending signals using preallocated sigqueue
1479 * structures. This is needed "because realtime applications cannot
1480 * afford to lose notifications of asynchronous events, like timer
1481 * expirations or I/O completions". In the case of POSIX Timers
1482 * we allocate the sigqueue structure from the timer_create. If this
1483 * allocation fails we are able to report the failure to the application
1484 * with an EAGAIN error.
1485 */
1486struct sigqueue *sigqueue_alloc(void)
1487{
1488 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1489
1490 if (q)
1491 q->flags |= SIGQUEUE_PREALLOC;
1492
1493 return q;
1494}
1495
1496void sigqueue_free(struct sigqueue *q)
1497{
1498 unsigned long flags;
1499 spinlock_t *lock = ¤t->sighand->siglock;
1500
1501 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1502 /*
1503 * We must hold ->siglock while testing q->list
1504 * to serialize with collect_signal() or with
1505 * __exit_signal()->flush_sigqueue().
1506 */
1507 spin_lock_irqsave(lock, flags);
1508 q->flags &= ~SIGQUEUE_PREALLOC;
1509 /*
1510 * If it is queued it will be freed when dequeued,
1511 * like the "regular" sigqueue.
1512 */
1513 if (!list_empty(&q->list))
1514 q = NULL;
1515 spin_unlock_irqrestore(lock, flags);
1516
1517 if (q)
1518 __sigqueue_free(q);
1519}
1520
1521int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1522{
1523 int sig = q->info.si_signo;
1524 struct sigpending *pending;
1525 unsigned long flags;
1526 int ret, result;
1527
1528 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1529
1530 ret = -1;
1531 if (!likely(lock_task_sighand(t, &flags)))
1532 goto ret;
1533
1534 ret = 1; /* the signal is ignored */
1535 result = TRACE_SIGNAL_IGNORED;
1536 if (!prepare_signal(sig, t, false))
1537 goto out;
1538
1539 ret = 0;
1540 if (unlikely(!list_empty(&q->list))) {
1541 /*
1542 * If an SI_TIMER entry is already queue just increment
1543 * the overrun count.
1544 */
1545 BUG_ON(q->info.si_code != SI_TIMER);
1546 q->info.si_overrun++;
1547 result = TRACE_SIGNAL_ALREADY_PENDING;
1548 goto out;
1549 }
1550 q->info.si_overrun = 0;
1551
1552 signalfd_notify(t, sig);
1553 pending = group ? &t->signal->shared_pending : &t->pending;
1554 list_add_tail(&q->list, &pending->list);
1555 sigaddset(&pending->signal, sig);
1556 complete_signal(sig, t, group);
1557 result = TRACE_SIGNAL_DELIVERED;
1558out:
1559 trace_signal_generate(sig, &q->info, t, group, result);
1560 unlock_task_sighand(t, &flags);
1561ret:
1562 return ret;
1563}
1564
1565/*
1566 * Let a parent know about the death of a child.
1567 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1568 *
1569 * Returns true if our parent ignored us and so we've switched to
1570 * self-reaping.
1571 */
1572bool do_notify_parent(struct task_struct *tsk, int sig)
1573{
1574 struct siginfo info;
1575 unsigned long flags;
1576 struct sighand_struct *psig;
1577 bool autoreap = false;
1578 cputime_t utime, stime;
1579
1580 BUG_ON(sig == -1);
1581
1582 /* do_notify_parent_cldstop should have been called instead. */
1583 BUG_ON(task_is_stopped_or_traced(tsk));
1584
1585 BUG_ON(!tsk->ptrace &&
1586 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1587
1588 if (sig != SIGCHLD) {
1589 /*
1590 * This is only possible if parent == real_parent.
1591 * Check if it has changed security domain.
1592 */
1593 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1594 sig = SIGCHLD;
1595 }
1596
1597 info.si_signo = sig;
1598 info.si_errno = 0;
1599 /*
1600 * We are under tasklist_lock here so our parent is tied to
1601 * us and cannot change.
1602 *
1603 * task_active_pid_ns will always return the same pid namespace
1604 * until a task passes through release_task.
1605 *
1606 * write_lock() currently calls preempt_disable() which is the
1607 * same as rcu_read_lock(), but according to Oleg, this is not
1608 * correct to rely on this
1609 */
1610 rcu_read_lock();
1611 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1612 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1613 task_uid(tsk));
1614 rcu_read_unlock();
1615
1616 task_cputime(tsk, &utime, &stime);
1617 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1618 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1619
1620 info.si_status = tsk->exit_code & 0x7f;
1621 if (tsk->exit_code & 0x80)
1622 info.si_code = CLD_DUMPED;
1623 else if (tsk->exit_code & 0x7f)
1624 info.si_code = CLD_KILLED;
1625 else {
1626 info.si_code = CLD_EXITED;
1627 info.si_status = tsk->exit_code >> 8;
1628 }
1629
1630 psig = tsk->parent->sighand;
1631 spin_lock_irqsave(&psig->siglock, flags);
1632 if (!tsk->ptrace && sig == SIGCHLD &&
1633 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1634 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1635 /*
1636 * We are exiting and our parent doesn't care. POSIX.1
1637 * defines special semantics for setting SIGCHLD to SIG_IGN
1638 * or setting the SA_NOCLDWAIT flag: we should be reaped
1639 * automatically and not left for our parent's wait4 call.
1640 * Rather than having the parent do it as a magic kind of
1641 * signal handler, we just set this to tell do_exit that we
1642 * can be cleaned up without becoming a zombie. Note that
1643 * we still call __wake_up_parent in this case, because a
1644 * blocked sys_wait4 might now return -ECHILD.
1645 *
1646 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1647 * is implementation-defined: we do (if you don't want
1648 * it, just use SIG_IGN instead).
1649 */
1650 autoreap = true;
1651 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1652 sig = 0;
1653 }
1654 if (valid_signal(sig) && sig)
1655 __group_send_sig_info(sig, &info, tsk->parent);
1656 __wake_up_parent(tsk, tsk->parent);
1657 spin_unlock_irqrestore(&psig->siglock, flags);
1658
1659 return autoreap;
1660}
1661
1662/**
1663 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1664 * @tsk: task reporting the state change
1665 * @for_ptracer: the notification is for ptracer
1666 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1667 *
1668 * Notify @tsk's parent that the stopped/continued state has changed. If
1669 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1670 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1671 *
1672 * CONTEXT:
1673 * Must be called with tasklist_lock at least read locked.
1674 */
1675static void do_notify_parent_cldstop(struct task_struct *tsk,
1676 bool for_ptracer, int why)
1677{
1678 struct siginfo info;
1679 unsigned long flags;
1680 struct task_struct *parent;
1681 struct sighand_struct *sighand;
1682 cputime_t utime, stime;
1683
1684 if (for_ptracer) {
1685 parent = tsk->parent;
1686 } else {
1687 tsk = tsk->group_leader;
1688 parent = tsk->real_parent;
1689 }
1690
1691 info.si_signo = SIGCHLD;
1692 info.si_errno = 0;
1693 /*
1694 * see comment in do_notify_parent() about the following 4 lines
1695 */
1696 rcu_read_lock();
1697 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1698 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1699 rcu_read_unlock();
1700
1701 task_cputime(tsk, &utime, &stime);
1702 info.si_utime = cputime_to_clock_t(utime);
1703 info.si_stime = cputime_to_clock_t(stime);
1704
1705 info.si_code = why;
1706 switch (why) {
1707 case CLD_CONTINUED:
1708 info.si_status = SIGCONT;
1709 break;
1710 case CLD_STOPPED:
1711 info.si_status = tsk->signal->group_exit_code & 0x7f;
1712 break;
1713 case CLD_TRAPPED:
1714 info.si_status = tsk->exit_code & 0x7f;
1715 break;
1716 default:
1717 BUG();
1718 }
1719
1720 sighand = parent->sighand;
1721 spin_lock_irqsave(&sighand->siglock, flags);
1722 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1723 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1724 __group_send_sig_info(SIGCHLD, &info, parent);
1725 /*
1726 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1727 */
1728 __wake_up_parent(tsk, parent);
1729 spin_unlock_irqrestore(&sighand->siglock, flags);
1730}
1731
1732static inline int may_ptrace_stop(void)
1733{
1734 if (!likely(current->ptrace))
1735 return 0;
1736 /*
1737 * Are we in the middle of do_coredump?
1738 * If so and our tracer is also part of the coredump stopping
1739 * is a deadlock situation, and pointless because our tracer
1740 * is dead so don't allow us to stop.
1741 * If SIGKILL was already sent before the caller unlocked
1742 * ->siglock we must see ->core_state != NULL. Otherwise it
1743 * is safe to enter schedule().
1744 *
1745 * This is almost outdated, a task with the pending SIGKILL can't
1746 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1747 * after SIGKILL was already dequeued.
1748 */
1749 if (unlikely(current->mm->core_state) &&
1750 unlikely(current->mm == current->parent->mm))
1751 return 0;
1752
1753 return 1;
1754}
1755
1756/*
1757 * Return non-zero if there is a SIGKILL that should be waking us up.
1758 * Called with the siglock held.
1759 */
1760static int sigkill_pending(struct task_struct *tsk)
1761{
1762 return sigismember(&tsk->pending.signal, SIGKILL) ||
1763 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1764}
1765
1766/*
1767 * This must be called with current->sighand->siglock held.
1768 *
1769 * This should be the path for all ptrace stops.
1770 * We always set current->last_siginfo while stopped here.
1771 * That makes it a way to test a stopped process for
1772 * being ptrace-stopped vs being job-control-stopped.
1773 *
1774 * If we actually decide not to stop at all because the tracer
1775 * is gone, we keep current->exit_code unless clear_code.
1776 */
1777static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1778 __releases(¤t->sighand->siglock)
1779 __acquires(¤t->sighand->siglock)
1780{
1781 bool gstop_done = false;
1782
1783 if (arch_ptrace_stop_needed(exit_code, info)) {
1784 /*
1785 * The arch code has something special to do before a
1786 * ptrace stop. This is allowed to block, e.g. for faults
1787 * on user stack pages. We can't keep the siglock while
1788 * calling arch_ptrace_stop, so we must release it now.
1789 * To preserve proper semantics, we must do this before
1790 * any signal bookkeeping like checking group_stop_count.
1791 * Meanwhile, a SIGKILL could come in before we retake the
1792 * siglock. That must prevent us from sleeping in TASK_TRACED.
1793 * So after regaining the lock, we must check for SIGKILL.
1794 */
1795 spin_unlock_irq(¤t->sighand->siglock);
1796 arch_ptrace_stop(exit_code, info);
1797 spin_lock_irq(¤t->sighand->siglock);
1798 if (sigkill_pending(current))
1799 return;
1800 }
1801
1802 /*
1803 * We're committing to trapping. TRACED should be visible before
1804 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1805 * Also, transition to TRACED and updates to ->jobctl should be
1806 * atomic with respect to siglock and should be done after the arch
1807 * hook as siglock is released and regrabbed across it.
1808 */
1809 set_current_state(TASK_TRACED);
1810
1811 current->last_siginfo = info;
1812 current->exit_code = exit_code;
1813
1814 /*
1815 * If @why is CLD_STOPPED, we're trapping to participate in a group
1816 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1817 * across siglock relocks since INTERRUPT was scheduled, PENDING
1818 * could be clear now. We act as if SIGCONT is received after
1819 * TASK_TRACED is entered - ignore it.
1820 */
1821 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1822 gstop_done = task_participate_group_stop(current);
1823
1824 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1825 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1826 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1827 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1828
1829 /* entering a trap, clear TRAPPING */
1830 task_clear_jobctl_trapping(current);
1831
1832 spin_unlock_irq(¤t->sighand->siglock);
1833 read_lock(&tasklist_lock);
1834 if (may_ptrace_stop()) {
1835 /*
1836 * Notify parents of the stop.
1837 *
1838 * While ptraced, there are two parents - the ptracer and
1839 * the real_parent of the group_leader. The ptracer should
1840 * know about every stop while the real parent is only
1841 * interested in the completion of group stop. The states
1842 * for the two don't interact with each other. Notify
1843 * separately unless they're gonna be duplicates.
1844 */
1845 do_notify_parent_cldstop(current, true, why);
1846 if (gstop_done && ptrace_reparented(current))
1847 do_notify_parent_cldstop(current, false, why);
1848
1849 /*
1850 * Don't want to allow preemption here, because
1851 * sys_ptrace() needs this task to be inactive.
1852 *
1853 * XXX: implement read_unlock_no_resched().
1854 */
1855 preempt_disable();
1856 read_unlock(&tasklist_lock);
1857 preempt_enable_no_resched();
1858 freezable_schedule();
1859 } else {
1860 /*
1861 * By the time we got the lock, our tracer went away.
1862 * Don't drop the lock yet, another tracer may come.
1863 *
1864 * If @gstop_done, the ptracer went away between group stop
1865 * completion and here. During detach, it would have set
1866 * JOBCTL_STOP_PENDING on us and we'll re-enter
1867 * TASK_STOPPED in do_signal_stop() on return, so notifying
1868 * the real parent of the group stop completion is enough.
1869 */
1870 if (gstop_done)
1871 do_notify_parent_cldstop(current, false, why);
1872
1873 /* tasklist protects us from ptrace_freeze_traced() */
1874 __set_current_state(TASK_RUNNING);
1875 if (clear_code)
1876 current->exit_code = 0;
1877 read_unlock(&tasklist_lock);
1878 }
1879
1880 /*
1881 * We are back. Now reacquire the siglock before touching
1882 * last_siginfo, so that we are sure to have synchronized with
1883 * any signal-sending on another CPU that wants to examine it.
1884 */
1885 spin_lock_irq(¤t->sighand->siglock);
1886 current->last_siginfo = NULL;
1887
1888 /* LISTENING can be set only during STOP traps, clear it */
1889 current->jobctl &= ~JOBCTL_LISTENING;
1890
1891 /*
1892 * Queued signals ignored us while we were stopped for tracing.
1893 * So check for any that we should take before resuming user mode.
1894 * This sets TIF_SIGPENDING, but never clears it.
1895 */
1896 recalc_sigpending_tsk(current);
1897}
1898
1899static void ptrace_do_notify(int signr, int exit_code, int why)
1900{
1901 siginfo_t info;
1902
1903 memset(&info, 0, sizeof info);
1904 info.si_signo = signr;
1905 info.si_code = exit_code;
1906 info.si_pid = task_pid_vnr(current);
1907 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1908
1909 /* Let the debugger run. */
1910 ptrace_stop(exit_code, why, 1, &info);
1911}
1912
1913void ptrace_notify(int exit_code)
1914{
1915 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1916 if (unlikely(current->task_works))
1917 task_work_run();
1918
1919 spin_lock_irq(¤t->sighand->siglock);
1920 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1921 spin_unlock_irq(¤t->sighand->siglock);
1922}
1923
1924/**
1925 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1926 * @signr: signr causing group stop if initiating
1927 *
1928 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1929 * and participate in it. If already set, participate in the existing
1930 * group stop. If participated in a group stop (and thus slept), %true is
1931 * returned with siglock released.
1932 *
1933 * If ptraced, this function doesn't handle stop itself. Instead,
1934 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1935 * untouched. The caller must ensure that INTERRUPT trap handling takes
1936 * places afterwards.
1937 *
1938 * CONTEXT:
1939 * Must be called with @current->sighand->siglock held, which is released
1940 * on %true return.
1941 *
1942 * RETURNS:
1943 * %false if group stop is already cancelled or ptrace trap is scheduled.
1944 * %true if participated in group stop.
1945 */
1946static bool do_signal_stop(int signr)
1947 __releases(¤t->sighand->siglock)
1948{
1949 struct signal_struct *sig = current->signal;
1950
1951 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1952 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1953 struct task_struct *t;
1954
1955 /* signr will be recorded in task->jobctl for retries */
1956 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1957
1958 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1959 unlikely(signal_group_exit(sig)))
1960 return false;
1961 /*
1962 * There is no group stop already in progress. We must
1963 * initiate one now.
1964 *
1965 * While ptraced, a task may be resumed while group stop is
1966 * still in effect and then receive a stop signal and
1967 * initiate another group stop. This deviates from the
1968 * usual behavior as two consecutive stop signals can't
1969 * cause two group stops when !ptraced. That is why we
1970 * also check !task_is_stopped(t) below.
1971 *
1972 * The condition can be distinguished by testing whether
1973 * SIGNAL_STOP_STOPPED is already set. Don't generate
1974 * group_exit_code in such case.
1975 *
1976 * This is not necessary for SIGNAL_STOP_CONTINUED because
1977 * an intervening stop signal is required to cause two
1978 * continued events regardless of ptrace.
1979 */
1980 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1981 sig->group_exit_code = signr;
1982
1983 sig->group_stop_count = 0;
1984
1985 if (task_set_jobctl_pending(current, signr | gstop))
1986 sig->group_stop_count++;
1987
1988 t = current;
1989 while_each_thread(current, t) {
1990 /*
1991 * Setting state to TASK_STOPPED for a group
1992 * stop is always done with the siglock held,
1993 * so this check has no races.
1994 */
1995 if (!task_is_stopped(t) &&
1996 task_set_jobctl_pending(t, signr | gstop)) {
1997 sig->group_stop_count++;
1998 if (likely(!(t->ptrace & PT_SEIZED)))
1999 signal_wake_up(t, 0);
2000 else
2001 ptrace_trap_notify(t);
2002 }
2003 }
2004 }
2005
2006 if (likely(!current->ptrace)) {
2007 int notify = 0;
2008
2009 /*
2010 * If there are no other threads in the group, or if there
2011 * is a group stop in progress and we are the last to stop,
2012 * report to the parent.
2013 */
2014 if (task_participate_group_stop(current))
2015 notify = CLD_STOPPED;
2016
2017 __set_current_state(TASK_STOPPED);
2018 spin_unlock_irq(¤t->sighand->siglock);
2019
2020 /*
2021 * Notify the parent of the group stop completion. Because
2022 * we're not holding either the siglock or tasklist_lock
2023 * here, ptracer may attach inbetween; however, this is for
2024 * group stop and should always be delivered to the real
2025 * parent of the group leader. The new ptracer will get
2026 * its notification when this task transitions into
2027 * TASK_TRACED.
2028 */
2029 if (notify) {
2030 read_lock(&tasklist_lock);
2031 do_notify_parent_cldstop(current, false, notify);
2032 read_unlock(&tasklist_lock);
2033 }
2034
2035 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2036 freezable_schedule();
2037 return true;
2038 } else {
2039 /*
2040 * While ptraced, group stop is handled by STOP trap.
2041 * Schedule it and let the caller deal with it.
2042 */
2043 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2044 return false;
2045 }
2046}
2047
2048/**
2049 * do_jobctl_trap - take care of ptrace jobctl traps
2050 *
2051 * When PT_SEIZED, it's used for both group stop and explicit
2052 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2053 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2054 * the stop signal; otherwise, %SIGTRAP.
2055 *
2056 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2057 * number as exit_code and no siginfo.
2058 *
2059 * CONTEXT:
2060 * Must be called with @current->sighand->siglock held, which may be
2061 * released and re-acquired before returning with intervening sleep.
2062 */
2063static void do_jobctl_trap(void)
2064{
2065 struct signal_struct *signal = current->signal;
2066 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2067
2068 if (current->ptrace & PT_SEIZED) {
2069 if (!signal->group_stop_count &&
2070 !(signal->flags & SIGNAL_STOP_STOPPED))
2071 signr = SIGTRAP;
2072 WARN_ON_ONCE(!signr);
2073 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2074 CLD_STOPPED);
2075 } else {
2076 WARN_ON_ONCE(!signr);
2077 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2078 current->exit_code = 0;
2079 }
2080}
2081
2082static int ptrace_signal(int signr, siginfo_t *info)
2083{
2084 ptrace_signal_deliver();
2085 /*
2086 * We do not check sig_kernel_stop(signr) but set this marker
2087 * unconditionally because we do not know whether debugger will
2088 * change signr. This flag has no meaning unless we are going
2089 * to stop after return from ptrace_stop(). In this case it will
2090 * be checked in do_signal_stop(), we should only stop if it was
2091 * not cleared by SIGCONT while we were sleeping. See also the
2092 * comment in dequeue_signal().
2093 */
2094 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2095 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2096
2097 /* We're back. Did the debugger cancel the sig? */
2098 signr = current->exit_code;
2099 if (signr == 0)
2100 return signr;
2101
2102 current->exit_code = 0;
2103
2104 /*
2105 * Update the siginfo structure if the signal has
2106 * changed. If the debugger wanted something
2107 * specific in the siginfo structure then it should
2108 * have updated *info via PTRACE_SETSIGINFO.
2109 */
2110 if (signr != info->si_signo) {
2111 info->si_signo = signr;
2112 info->si_errno = 0;
2113 info->si_code = SI_USER;
2114 rcu_read_lock();
2115 info->si_pid = task_pid_vnr(current->parent);
2116 info->si_uid = from_kuid_munged(current_user_ns(),
2117 task_uid(current->parent));
2118 rcu_read_unlock();
2119 }
2120
2121 /* If the (new) signal is now blocked, requeue it. */
2122 if (sigismember(¤t->blocked, signr)) {
2123 specific_send_sig_info(signr, info, current);
2124 signr = 0;
2125 }
2126
2127 return signr;
2128}
2129
2130int get_signal(struct ksignal *ksig)
2131{
2132 struct sighand_struct *sighand = current->sighand;
2133 struct signal_struct *signal = current->signal;
2134 int signr;
2135
2136 if (unlikely(current->task_works))
2137 task_work_run();
2138
2139 if (unlikely(uprobe_deny_signal()))
2140 return 0;
2141
2142 /*
2143 * Do this once, we can't return to user-mode if freezing() == T.
2144 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2145 * thus do not need another check after return.
2146 */
2147 try_to_freeze();
2148
2149relock:
2150 spin_lock_irq(&sighand->siglock);
2151 /*
2152 * Every stopped thread goes here after wakeup. Check to see if
2153 * we should notify the parent, prepare_signal(SIGCONT) encodes
2154 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2155 */
2156 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2157 int why;
2158
2159 if (signal->flags & SIGNAL_CLD_CONTINUED)
2160 why = CLD_CONTINUED;
2161 else
2162 why = CLD_STOPPED;
2163
2164 signal->flags &= ~SIGNAL_CLD_MASK;
2165
2166 spin_unlock_irq(&sighand->siglock);
2167
2168 /*
2169 * Notify the parent that we're continuing. This event is
2170 * always per-process and doesn't make whole lot of sense
2171 * for ptracers, who shouldn't consume the state via
2172 * wait(2) either, but, for backward compatibility, notify
2173 * the ptracer of the group leader too unless it's gonna be
2174 * a duplicate.
2175 */
2176 read_lock(&tasklist_lock);
2177 do_notify_parent_cldstop(current, false, why);
2178
2179 if (ptrace_reparented(current->group_leader))
2180 do_notify_parent_cldstop(current->group_leader,
2181 true, why);
2182 read_unlock(&tasklist_lock);
2183
2184 goto relock;
2185 }
2186
2187 for (;;) {
2188 struct k_sigaction *ka;
2189
2190 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2191 do_signal_stop(0))
2192 goto relock;
2193
2194 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2195 do_jobctl_trap();
2196 spin_unlock_irq(&sighand->siglock);
2197 goto relock;
2198 }
2199
2200 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2201
2202 if (!signr)
2203 break; /* will return 0 */
2204
2205 if (unlikely(current->ptrace) && signr != SIGKILL) {
2206 signr = ptrace_signal(signr, &ksig->info);
2207 if (!signr)
2208 continue;
2209 }
2210
2211 ka = &sighand->action[signr-1];
2212
2213 /* Trace actually delivered signals. */
2214 trace_signal_deliver(signr, &ksig->info, ka);
2215
2216 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2217 continue;
2218 if (ka->sa.sa_handler != SIG_DFL) {
2219 /* Run the handler. */
2220 ksig->ka = *ka;
2221
2222 if (ka->sa.sa_flags & SA_ONESHOT)
2223 ka->sa.sa_handler = SIG_DFL;
2224
2225 break; /* will return non-zero "signr" value */
2226 }
2227
2228 /*
2229 * Now we are doing the default action for this signal.
2230 */
2231 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2232 continue;
2233
2234 /*
2235 * Global init gets no signals it doesn't want.
2236 * Container-init gets no signals it doesn't want from same
2237 * container.
2238 *
2239 * Note that if global/container-init sees a sig_kernel_only()
2240 * signal here, the signal must have been generated internally
2241 * or must have come from an ancestor namespace. In either
2242 * case, the signal cannot be dropped.
2243 */
2244 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2245 !sig_kernel_only(signr))
2246 continue;
2247
2248 if (sig_kernel_stop(signr)) {
2249 /*
2250 * The default action is to stop all threads in
2251 * the thread group. The job control signals
2252 * do nothing in an orphaned pgrp, but SIGSTOP
2253 * always works. Note that siglock needs to be
2254 * dropped during the call to is_orphaned_pgrp()
2255 * because of lock ordering with tasklist_lock.
2256 * This allows an intervening SIGCONT to be posted.
2257 * We need to check for that and bail out if necessary.
2258 */
2259 if (signr != SIGSTOP) {
2260 spin_unlock_irq(&sighand->siglock);
2261
2262 /* signals can be posted during this window */
2263
2264 if (is_current_pgrp_orphaned())
2265 goto relock;
2266
2267 spin_lock_irq(&sighand->siglock);
2268 }
2269
2270 if (likely(do_signal_stop(ksig->info.si_signo))) {
2271 /* It released the siglock. */
2272 goto relock;
2273 }
2274
2275 /*
2276 * We didn't actually stop, due to a race
2277 * with SIGCONT or something like that.
2278 */
2279 continue;
2280 }
2281
2282 spin_unlock_irq(&sighand->siglock);
2283
2284 /*
2285 * Anything else is fatal, maybe with a core dump.
2286 */
2287 current->flags |= PF_SIGNALED;
2288
2289 if (sig_kernel_coredump(signr)) {
2290 if (print_fatal_signals)
2291 print_fatal_signal(ksig->info.si_signo);
2292 proc_coredump_connector(current);
2293 /*
2294 * If it was able to dump core, this kills all
2295 * other threads in the group and synchronizes with
2296 * their demise. If we lost the race with another
2297 * thread getting here, it set group_exit_code
2298 * first and our do_group_exit call below will use
2299 * that value and ignore the one we pass it.
2300 */
2301 do_coredump(&ksig->info);
2302 }
2303
2304 /*
2305 * Death signals, no core dump.
2306 */
2307 do_group_exit(ksig->info.si_signo);
2308 /* NOTREACHED */
2309 }
2310 spin_unlock_irq(&sighand->siglock);
2311
2312 ksig->sig = signr;
2313 return ksig->sig > 0;
2314}
2315
2316/**
2317 * signal_delivered -
2318 * @ksig: kernel signal struct
2319 * @stepping: nonzero if debugger single-step or block-step in use
2320 *
2321 * This function should be called when a signal has successfully been
2322 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2323 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2324 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2325 */
2326static void signal_delivered(struct ksignal *ksig, int stepping)
2327{
2328 sigset_t blocked;
2329
2330 /* A signal was successfully delivered, and the
2331 saved sigmask was stored on the signal frame,
2332 and will be restored by sigreturn. So we can
2333 simply clear the restore sigmask flag. */
2334 clear_restore_sigmask();
2335
2336 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2337 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2338 sigaddset(&blocked, ksig->sig);
2339 set_current_blocked(&blocked);
2340 tracehook_signal_handler(stepping);
2341}
2342
2343void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2344{
2345 if (failed)
2346 force_sigsegv(ksig->sig, current);
2347 else
2348 signal_delivered(ksig, stepping);
2349}
2350
2351/*
2352 * It could be that complete_signal() picked us to notify about the
2353 * group-wide signal. Other threads should be notified now to take
2354 * the shared signals in @which since we will not.
2355 */
2356static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2357{
2358 sigset_t retarget;
2359 struct task_struct *t;
2360
2361 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2362 if (sigisemptyset(&retarget))
2363 return;
2364
2365 t = tsk;
2366 while_each_thread(tsk, t) {
2367 if (t->flags & PF_EXITING)
2368 continue;
2369
2370 if (!has_pending_signals(&retarget, &t->blocked))
2371 continue;
2372 /* Remove the signals this thread can handle. */
2373 sigandsets(&retarget, &retarget, &t->blocked);
2374
2375 if (!signal_pending(t))
2376 signal_wake_up(t, 0);
2377
2378 if (sigisemptyset(&retarget))
2379 break;
2380 }
2381}
2382
2383void exit_signals(struct task_struct *tsk)
2384{
2385 int group_stop = 0;
2386 sigset_t unblocked;
2387
2388 /*
2389 * @tsk is about to have PF_EXITING set - lock out users which
2390 * expect stable threadgroup.
2391 */
2392 threadgroup_change_begin(tsk);
2393
2394 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2395 tsk->flags |= PF_EXITING;
2396 threadgroup_change_end(tsk);
2397 return;
2398 }
2399
2400 spin_lock_irq(&tsk->sighand->siglock);
2401 /*
2402 * From now this task is not visible for group-wide signals,
2403 * see wants_signal(), do_signal_stop().
2404 */
2405 tsk->flags |= PF_EXITING;
2406
2407 threadgroup_change_end(tsk);
2408
2409 if (!signal_pending(tsk))
2410 goto out;
2411
2412 unblocked = tsk->blocked;
2413 signotset(&unblocked);
2414 retarget_shared_pending(tsk, &unblocked);
2415
2416 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2417 task_participate_group_stop(tsk))
2418 group_stop = CLD_STOPPED;
2419out:
2420 spin_unlock_irq(&tsk->sighand->siglock);
2421
2422 /*
2423 * If group stop has completed, deliver the notification. This
2424 * should always go to the real parent of the group leader.
2425 */
2426 if (unlikely(group_stop)) {
2427 read_lock(&tasklist_lock);
2428 do_notify_parent_cldstop(tsk, false, group_stop);
2429 read_unlock(&tasklist_lock);
2430 }
2431}
2432
2433EXPORT_SYMBOL(recalc_sigpending);
2434EXPORT_SYMBOL_GPL(dequeue_signal);
2435EXPORT_SYMBOL(flush_signals);
2436EXPORT_SYMBOL(force_sig);
2437EXPORT_SYMBOL(send_sig);
2438EXPORT_SYMBOL(send_sig_info);
2439EXPORT_SYMBOL(sigprocmask);
2440
2441/*
2442 * System call entry points.
2443 */
2444
2445/**
2446 * sys_restart_syscall - restart a system call
2447 */
2448SYSCALL_DEFINE0(restart_syscall)
2449{
2450 struct restart_block *restart = ¤t->restart_block;
2451 return restart->fn(restart);
2452}
2453
2454long do_no_restart_syscall(struct restart_block *param)
2455{
2456 return -EINTR;
2457}
2458
2459static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2460{
2461 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2462 sigset_t newblocked;
2463 /* A set of now blocked but previously unblocked signals. */
2464 sigandnsets(&newblocked, newset, ¤t->blocked);
2465 retarget_shared_pending(tsk, &newblocked);
2466 }
2467 tsk->blocked = *newset;
2468 recalc_sigpending();
2469}
2470
2471/**
2472 * set_current_blocked - change current->blocked mask
2473 * @newset: new mask
2474 *
2475 * It is wrong to change ->blocked directly, this helper should be used
2476 * to ensure the process can't miss a shared signal we are going to block.
2477 */
2478void set_current_blocked(sigset_t *newset)
2479{
2480 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2481 __set_current_blocked(newset);
2482}
2483
2484void __set_current_blocked(const sigset_t *newset)
2485{
2486 struct task_struct *tsk = current;
2487
2488 spin_lock_irq(&tsk->sighand->siglock);
2489 __set_task_blocked(tsk, newset);
2490 spin_unlock_irq(&tsk->sighand->siglock);
2491}
2492
2493/*
2494 * This is also useful for kernel threads that want to temporarily
2495 * (or permanently) block certain signals.
2496 *
2497 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2498 * interface happily blocks "unblockable" signals like SIGKILL
2499 * and friends.
2500 */
2501int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2502{
2503 struct task_struct *tsk = current;
2504 sigset_t newset;
2505
2506 /* Lockless, only current can change ->blocked, never from irq */
2507 if (oldset)
2508 *oldset = tsk->blocked;
2509
2510 switch (how) {
2511 case SIG_BLOCK:
2512 sigorsets(&newset, &tsk->blocked, set);
2513 break;
2514 case SIG_UNBLOCK:
2515 sigandnsets(&newset, &tsk->blocked, set);
2516 break;
2517 case SIG_SETMASK:
2518 newset = *set;
2519 break;
2520 default:
2521 return -EINVAL;
2522 }
2523
2524 __set_current_blocked(&newset);
2525 return 0;
2526}
2527
2528/**
2529 * sys_rt_sigprocmask - change the list of currently blocked signals
2530 * @how: whether to add, remove, or set signals
2531 * @nset: stores pending signals
2532 * @oset: previous value of signal mask if non-null
2533 * @sigsetsize: size of sigset_t type
2534 */
2535SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2536 sigset_t __user *, oset, size_t, sigsetsize)
2537{
2538 sigset_t old_set, new_set;
2539 int error;
2540
2541 /* XXX: Don't preclude handling different sized sigset_t's. */
2542 if (sigsetsize != sizeof(sigset_t))
2543 return -EINVAL;
2544
2545 old_set = current->blocked;
2546
2547 if (nset) {
2548 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2549 return -EFAULT;
2550 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2551
2552 error = sigprocmask(how, &new_set, NULL);
2553 if (error)
2554 return error;
2555 }
2556
2557 if (oset) {
2558 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2559 return -EFAULT;
2560 }
2561
2562 return 0;
2563}
2564
2565#ifdef CONFIG_COMPAT
2566COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2567 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2568{
2569#ifdef __BIG_ENDIAN
2570 sigset_t old_set = current->blocked;
2571
2572 /* XXX: Don't preclude handling different sized sigset_t's. */
2573 if (sigsetsize != sizeof(sigset_t))
2574 return -EINVAL;
2575
2576 if (nset) {
2577 compat_sigset_t new32;
2578 sigset_t new_set;
2579 int error;
2580 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2581 return -EFAULT;
2582
2583 sigset_from_compat(&new_set, &new32);
2584 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2585
2586 error = sigprocmask(how, &new_set, NULL);
2587 if (error)
2588 return error;
2589 }
2590 if (oset) {
2591 compat_sigset_t old32;
2592 sigset_to_compat(&old32, &old_set);
2593 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2594 return -EFAULT;
2595 }
2596 return 0;
2597#else
2598 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2599 (sigset_t __user *)oset, sigsetsize);
2600#endif
2601}
2602#endif
2603
2604static int do_sigpending(void *set, unsigned long sigsetsize)
2605{
2606 if (sigsetsize > sizeof(sigset_t))
2607 return -EINVAL;
2608
2609 spin_lock_irq(¤t->sighand->siglock);
2610 sigorsets(set, ¤t->pending.signal,
2611 ¤t->signal->shared_pending.signal);
2612 spin_unlock_irq(¤t->sighand->siglock);
2613
2614 /* Outside the lock because only this thread touches it. */
2615 sigandsets(set, ¤t->blocked, set);
2616 return 0;
2617}
2618
2619/**
2620 * sys_rt_sigpending - examine a pending signal that has been raised
2621 * while blocked
2622 * @uset: stores pending signals
2623 * @sigsetsize: size of sigset_t type or larger
2624 */
2625SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2626{
2627 sigset_t set;
2628 int err = do_sigpending(&set, sigsetsize);
2629 if (!err && copy_to_user(uset, &set, sigsetsize))
2630 err = -EFAULT;
2631 return err;
2632}
2633
2634#ifdef CONFIG_COMPAT
2635COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2636 compat_size_t, sigsetsize)
2637{
2638#ifdef __BIG_ENDIAN
2639 sigset_t set;
2640 int err = do_sigpending(&set, sigsetsize);
2641 if (!err) {
2642 compat_sigset_t set32;
2643 sigset_to_compat(&set32, &set);
2644 /* we can get here only if sigsetsize <= sizeof(set) */
2645 if (copy_to_user(uset, &set32, sigsetsize))
2646 err = -EFAULT;
2647 }
2648 return err;
2649#else
2650 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2651#endif
2652}
2653#endif
2654
2655#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2656
2657int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2658{
2659 int err;
2660
2661 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2662 return -EFAULT;
2663 if (from->si_code < 0)
2664 return __copy_to_user(to, from, sizeof(siginfo_t))
2665 ? -EFAULT : 0;
2666 /*
2667 * If you change siginfo_t structure, please be sure
2668 * this code is fixed accordingly.
2669 * Please remember to update the signalfd_copyinfo() function
2670 * inside fs/signalfd.c too, in case siginfo_t changes.
2671 * It should never copy any pad contained in the structure
2672 * to avoid security leaks, but must copy the generic
2673 * 3 ints plus the relevant union member.
2674 */
2675 err = __put_user(from->si_signo, &to->si_signo);
2676 err |= __put_user(from->si_errno, &to->si_errno);
2677 err |= __put_user((short)from->si_code, &to->si_code);
2678 switch (from->si_code & __SI_MASK) {
2679 case __SI_KILL:
2680 err |= __put_user(from->si_pid, &to->si_pid);
2681 err |= __put_user(from->si_uid, &to->si_uid);
2682 break;
2683 case __SI_TIMER:
2684 err |= __put_user(from->si_tid, &to->si_tid);
2685 err |= __put_user(from->si_overrun, &to->si_overrun);
2686 err |= __put_user(from->si_ptr, &to->si_ptr);
2687 break;
2688 case __SI_POLL:
2689 err |= __put_user(from->si_band, &to->si_band);
2690 err |= __put_user(from->si_fd, &to->si_fd);
2691 break;
2692 case __SI_FAULT:
2693 err |= __put_user(from->si_addr, &to->si_addr);
2694#ifdef __ARCH_SI_TRAPNO
2695 err |= __put_user(from->si_trapno, &to->si_trapno);
2696#endif
2697#ifdef BUS_MCEERR_AO
2698 /*
2699 * Other callers might not initialize the si_lsb field,
2700 * so check explicitly for the right codes here.
2701 */
2702 if (from->si_signo == SIGBUS &&
2703 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2704 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2705#endif
2706#ifdef SEGV_BNDERR
2707 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2708 err |= __put_user(from->si_lower, &to->si_lower);
2709 err |= __put_user(from->si_upper, &to->si_upper);
2710 }
2711#endif
2712#ifdef SEGV_PKUERR
2713 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2714 err |= __put_user(from->si_pkey, &to->si_pkey);
2715#endif
2716 break;
2717 case __SI_CHLD:
2718 err |= __put_user(from->si_pid, &to->si_pid);
2719 err |= __put_user(from->si_uid, &to->si_uid);
2720 err |= __put_user(from->si_status, &to->si_status);
2721 err |= __put_user(from->si_utime, &to->si_utime);
2722 err |= __put_user(from->si_stime, &to->si_stime);
2723 break;
2724 case __SI_RT: /* This is not generated by the kernel as of now. */
2725 case __SI_MESGQ: /* But this is */
2726 err |= __put_user(from->si_pid, &to->si_pid);
2727 err |= __put_user(from->si_uid, &to->si_uid);
2728 err |= __put_user(from->si_ptr, &to->si_ptr);
2729 break;
2730#ifdef __ARCH_SIGSYS
2731 case __SI_SYS:
2732 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2733 err |= __put_user(from->si_syscall, &to->si_syscall);
2734 err |= __put_user(from->si_arch, &to->si_arch);
2735 break;
2736#endif
2737 default: /* this is just in case for now ... */
2738 err |= __put_user(from->si_pid, &to->si_pid);
2739 err |= __put_user(from->si_uid, &to->si_uid);
2740 break;
2741 }
2742 return err;
2743}
2744
2745#endif
2746
2747/**
2748 * do_sigtimedwait - wait for queued signals specified in @which
2749 * @which: queued signals to wait for
2750 * @info: if non-null, the signal's siginfo is returned here
2751 * @ts: upper bound on process time suspension
2752 */
2753int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2754 const struct timespec *ts)
2755{
2756 struct task_struct *tsk = current;
2757 long timeout = MAX_SCHEDULE_TIMEOUT;
2758 sigset_t mask = *which;
2759 int sig;
2760
2761 if (ts) {
2762 if (!timespec_valid(ts))
2763 return -EINVAL;
2764 timeout = timespec_to_jiffies(ts);
2765 /*
2766 * We can be close to the next tick, add another one
2767 * to ensure we will wait at least the time asked for.
2768 */
2769 if (ts->tv_sec || ts->tv_nsec)
2770 timeout++;
2771 }
2772
2773 /*
2774 * Invert the set of allowed signals to get those we want to block.
2775 */
2776 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2777 signotset(&mask);
2778
2779 spin_lock_irq(&tsk->sighand->siglock);
2780 sig = dequeue_signal(tsk, &mask, info);
2781 if (!sig && timeout) {
2782 /*
2783 * None ready, temporarily unblock those we're interested
2784 * while we are sleeping in so that we'll be awakened when
2785 * they arrive. Unblocking is always fine, we can avoid
2786 * set_current_blocked().
2787 */
2788 tsk->real_blocked = tsk->blocked;
2789 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2790 recalc_sigpending();
2791 spin_unlock_irq(&tsk->sighand->siglock);
2792
2793 timeout = freezable_schedule_timeout_interruptible(timeout);
2794
2795 spin_lock_irq(&tsk->sighand->siglock);
2796 __set_task_blocked(tsk, &tsk->real_blocked);
2797 sigemptyset(&tsk->real_blocked);
2798 sig = dequeue_signal(tsk, &mask, info);
2799 }
2800 spin_unlock_irq(&tsk->sighand->siglock);
2801
2802 if (sig)
2803 return sig;
2804 return timeout ? -EINTR : -EAGAIN;
2805}
2806
2807/**
2808 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2809 * in @uthese
2810 * @uthese: queued signals to wait for
2811 * @uinfo: if non-null, the signal's siginfo is returned here
2812 * @uts: upper bound on process time suspension
2813 * @sigsetsize: size of sigset_t type
2814 */
2815SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2816 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2817 size_t, sigsetsize)
2818{
2819 sigset_t these;
2820 struct timespec ts;
2821 siginfo_t info;
2822 int ret;
2823
2824 /* XXX: Don't preclude handling different sized sigset_t's. */
2825 if (sigsetsize != sizeof(sigset_t))
2826 return -EINVAL;
2827
2828 if (copy_from_user(&these, uthese, sizeof(these)))
2829 return -EFAULT;
2830
2831 if (uts) {
2832 if (copy_from_user(&ts, uts, sizeof(ts)))
2833 return -EFAULT;
2834 }
2835
2836 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2837
2838 if (ret > 0 && uinfo) {
2839 if (copy_siginfo_to_user(uinfo, &info))
2840 ret = -EFAULT;
2841 }
2842
2843 return ret;
2844}
2845
2846/**
2847 * sys_kill - send a signal to a process
2848 * @pid: the PID of the process
2849 * @sig: signal to be sent
2850 */
2851SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2852{
2853 struct siginfo info;
2854
2855 info.si_signo = sig;
2856 info.si_errno = 0;
2857 info.si_code = SI_USER;
2858 info.si_pid = task_tgid_vnr(current);
2859 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2860
2861 return kill_something_info(sig, &info, pid);
2862}
2863
2864static int
2865do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2866{
2867 struct task_struct *p;
2868 int error = -ESRCH;
2869
2870 rcu_read_lock();
2871 p = find_task_by_vpid(pid);
2872 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2873 error = check_kill_permission(sig, info, p);
2874 /*
2875 * The null signal is a permissions and process existence
2876 * probe. No signal is actually delivered.
2877 */
2878 if (!error && sig) {
2879 error = do_send_sig_info(sig, info, p, false);
2880 /*
2881 * If lock_task_sighand() failed we pretend the task
2882 * dies after receiving the signal. The window is tiny,
2883 * and the signal is private anyway.
2884 */
2885 if (unlikely(error == -ESRCH))
2886 error = 0;
2887 }
2888 }
2889 rcu_read_unlock();
2890
2891 return error;
2892}
2893
2894static int do_tkill(pid_t tgid, pid_t pid, int sig)
2895{
2896 struct siginfo info = {};
2897
2898 info.si_signo = sig;
2899 info.si_errno = 0;
2900 info.si_code = SI_TKILL;
2901 info.si_pid = task_tgid_vnr(current);
2902 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2903
2904 return do_send_specific(tgid, pid, sig, &info);
2905}
2906
2907/**
2908 * sys_tgkill - send signal to one specific thread
2909 * @tgid: the thread group ID of the thread
2910 * @pid: the PID of the thread
2911 * @sig: signal to be sent
2912 *
2913 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2914 * exists but it's not belonging to the target process anymore. This
2915 * method solves the problem of threads exiting and PIDs getting reused.
2916 */
2917SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2918{
2919 /* This is only valid for single tasks */
2920 if (pid <= 0 || tgid <= 0)
2921 return -EINVAL;
2922
2923 return do_tkill(tgid, pid, sig);
2924}
2925
2926/**
2927 * sys_tkill - send signal to one specific task
2928 * @pid: the PID of the task
2929 * @sig: signal to be sent
2930 *
2931 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2932 */
2933SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2934{
2935 /* This is only valid for single tasks */
2936 if (pid <= 0)
2937 return -EINVAL;
2938
2939 return do_tkill(0, pid, sig);
2940}
2941
2942static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2943{
2944 /* Not even root can pretend to send signals from the kernel.
2945 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2946 */
2947 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2948 (task_pid_vnr(current) != pid))
2949 return -EPERM;
2950
2951 info->si_signo = sig;
2952
2953 /* POSIX.1b doesn't mention process groups. */
2954 return kill_proc_info(sig, info, pid);
2955}
2956
2957/**
2958 * sys_rt_sigqueueinfo - send signal information to a signal
2959 * @pid: the PID of the thread
2960 * @sig: signal to be sent
2961 * @uinfo: signal info to be sent
2962 */
2963SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2964 siginfo_t __user *, uinfo)
2965{
2966 siginfo_t info;
2967 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2968 return -EFAULT;
2969 return do_rt_sigqueueinfo(pid, sig, &info);
2970}
2971
2972#ifdef CONFIG_COMPAT
2973COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
2974 compat_pid_t, pid,
2975 int, sig,
2976 struct compat_siginfo __user *, uinfo)
2977{
2978 siginfo_t info = {};
2979 int ret = copy_siginfo_from_user32(&info, uinfo);
2980 if (unlikely(ret))
2981 return ret;
2982 return do_rt_sigqueueinfo(pid, sig, &info);
2983}
2984#endif
2985
2986static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2987{
2988 /* This is only valid for single tasks */
2989 if (pid <= 0 || tgid <= 0)
2990 return -EINVAL;
2991
2992 /* Not even root can pretend to send signals from the kernel.
2993 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2994 */
2995 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2996 (task_pid_vnr(current) != pid))
2997 return -EPERM;
2998
2999 info->si_signo = sig;
3000
3001 return do_send_specific(tgid, pid, sig, info);
3002}
3003
3004SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3005 siginfo_t __user *, uinfo)
3006{
3007 siginfo_t info;
3008
3009 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3010 return -EFAULT;
3011
3012 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3013}
3014
3015#ifdef CONFIG_COMPAT
3016COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3017 compat_pid_t, tgid,
3018 compat_pid_t, pid,
3019 int, sig,
3020 struct compat_siginfo __user *, uinfo)
3021{
3022 siginfo_t info = {};
3023
3024 if (copy_siginfo_from_user32(&info, uinfo))
3025 return -EFAULT;
3026 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3027}
3028#endif
3029
3030/*
3031 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3032 */
3033void kernel_sigaction(int sig, __sighandler_t action)
3034{
3035 spin_lock_irq(¤t->sighand->siglock);
3036 current->sighand->action[sig - 1].sa.sa_handler = action;
3037 if (action == SIG_IGN) {
3038 sigset_t mask;
3039
3040 sigemptyset(&mask);
3041 sigaddset(&mask, sig);
3042
3043 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3044 flush_sigqueue_mask(&mask, ¤t->pending);
3045 recalc_sigpending();
3046 }
3047 spin_unlock_irq(¤t->sighand->siglock);
3048}
3049EXPORT_SYMBOL(kernel_sigaction);
3050
3051int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3052{
3053 struct task_struct *p = current, *t;
3054 struct k_sigaction *k;
3055 sigset_t mask;
3056
3057 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3058 return -EINVAL;
3059
3060 k = &p->sighand->action[sig-1];
3061
3062 spin_lock_irq(&p->sighand->siglock);
3063 if (oact)
3064 *oact = *k;
3065
3066 if (act) {
3067 sigdelsetmask(&act->sa.sa_mask,
3068 sigmask(SIGKILL) | sigmask(SIGSTOP));
3069 *k = *act;
3070 /*
3071 * POSIX 3.3.1.3:
3072 * "Setting a signal action to SIG_IGN for a signal that is
3073 * pending shall cause the pending signal to be discarded,
3074 * whether or not it is blocked."
3075 *
3076 * "Setting a signal action to SIG_DFL for a signal that is
3077 * pending and whose default action is to ignore the signal
3078 * (for example, SIGCHLD), shall cause the pending signal to
3079 * be discarded, whether or not it is blocked"
3080 */
3081 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3082 sigemptyset(&mask);
3083 sigaddset(&mask, sig);
3084 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3085 for_each_thread(p, t)
3086 flush_sigqueue_mask(&mask, &t->pending);
3087 }
3088 }
3089
3090 spin_unlock_irq(&p->sighand->siglock);
3091 return 0;
3092}
3093
3094static int
3095do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3096{
3097 stack_t oss;
3098 int error;
3099
3100 oss.ss_sp = (void __user *) current->sas_ss_sp;
3101 oss.ss_size = current->sas_ss_size;
3102 oss.ss_flags = sas_ss_flags(sp);
3103
3104 if (uss) {
3105 void __user *ss_sp;
3106 size_t ss_size;
3107 int ss_flags;
3108
3109 error = -EFAULT;
3110 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3111 goto out;
3112 error = __get_user(ss_sp, &uss->ss_sp) |
3113 __get_user(ss_flags, &uss->ss_flags) |
3114 __get_user(ss_size, &uss->ss_size);
3115 if (error)
3116 goto out;
3117
3118 error = -EPERM;
3119 if (on_sig_stack(sp))
3120 goto out;
3121
3122 error = -EINVAL;
3123 /*
3124 * Note - this code used to test ss_flags incorrectly:
3125 * old code may have been written using ss_flags==0
3126 * to mean ss_flags==SS_ONSTACK (as this was the only
3127 * way that worked) - this fix preserves that older
3128 * mechanism.
3129 */
3130 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3131 goto out;
3132
3133 if (ss_flags == SS_DISABLE) {
3134 ss_size = 0;
3135 ss_sp = NULL;
3136 } else {
3137 error = -ENOMEM;
3138 if (ss_size < MINSIGSTKSZ)
3139 goto out;
3140 }
3141
3142 current->sas_ss_sp = (unsigned long) ss_sp;
3143 current->sas_ss_size = ss_size;
3144 }
3145
3146 error = 0;
3147 if (uoss) {
3148 error = -EFAULT;
3149 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3150 goto out;
3151 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3152 __put_user(oss.ss_size, &uoss->ss_size) |
3153 __put_user(oss.ss_flags, &uoss->ss_flags);
3154 }
3155
3156out:
3157 return error;
3158}
3159SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3160{
3161 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3162}
3163
3164int restore_altstack(const stack_t __user *uss)
3165{
3166 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3167 /* squash all but EFAULT for now */
3168 return err == -EFAULT ? err : 0;
3169}
3170
3171int __save_altstack(stack_t __user *uss, unsigned long sp)
3172{
3173 struct task_struct *t = current;
3174 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3175 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3176 __put_user(t->sas_ss_size, &uss->ss_size);
3177}
3178
3179#ifdef CONFIG_COMPAT
3180COMPAT_SYSCALL_DEFINE2(sigaltstack,
3181 const compat_stack_t __user *, uss_ptr,
3182 compat_stack_t __user *, uoss_ptr)
3183{
3184 stack_t uss, uoss;
3185 int ret;
3186 mm_segment_t seg;
3187
3188 if (uss_ptr) {
3189 compat_stack_t uss32;
3190
3191 memset(&uss, 0, sizeof(stack_t));
3192 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3193 return -EFAULT;
3194 uss.ss_sp = compat_ptr(uss32.ss_sp);
3195 uss.ss_flags = uss32.ss_flags;
3196 uss.ss_size = uss32.ss_size;
3197 }
3198 seg = get_fs();
3199 set_fs(KERNEL_DS);
3200 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3201 (stack_t __force __user *) &uoss,
3202 compat_user_stack_pointer());
3203 set_fs(seg);
3204 if (ret >= 0 && uoss_ptr) {
3205 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3206 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3207 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3208 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3209 ret = -EFAULT;
3210 }
3211 return ret;
3212}
3213
3214int compat_restore_altstack(const compat_stack_t __user *uss)
3215{
3216 int err = compat_sys_sigaltstack(uss, NULL);
3217 /* squash all but -EFAULT for now */
3218 return err == -EFAULT ? err : 0;
3219}
3220
3221int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3222{
3223 struct task_struct *t = current;
3224 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3225 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3226 __put_user(t->sas_ss_size, &uss->ss_size);
3227}
3228#endif
3229
3230#ifdef __ARCH_WANT_SYS_SIGPENDING
3231
3232/**
3233 * sys_sigpending - examine pending signals
3234 * @set: where mask of pending signal is returned
3235 */
3236SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3237{
3238 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3239}
3240
3241#endif
3242
3243#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3244/**
3245 * sys_sigprocmask - examine and change blocked signals
3246 * @how: whether to add, remove, or set signals
3247 * @nset: signals to add or remove (if non-null)
3248 * @oset: previous value of signal mask if non-null
3249 *
3250 * Some platforms have their own version with special arguments;
3251 * others support only sys_rt_sigprocmask.
3252 */
3253
3254SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3255 old_sigset_t __user *, oset)
3256{
3257 old_sigset_t old_set, new_set;
3258 sigset_t new_blocked;
3259
3260 old_set = current->blocked.sig[0];
3261
3262 if (nset) {
3263 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3264 return -EFAULT;
3265
3266 new_blocked = current->blocked;
3267
3268 switch (how) {
3269 case SIG_BLOCK:
3270 sigaddsetmask(&new_blocked, new_set);
3271 break;
3272 case SIG_UNBLOCK:
3273 sigdelsetmask(&new_blocked, new_set);
3274 break;
3275 case SIG_SETMASK:
3276 new_blocked.sig[0] = new_set;
3277 break;
3278 default:
3279 return -EINVAL;
3280 }
3281
3282 set_current_blocked(&new_blocked);
3283 }
3284
3285 if (oset) {
3286 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3287 return -EFAULT;
3288 }
3289
3290 return 0;
3291}
3292#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3293
3294#ifndef CONFIG_ODD_RT_SIGACTION
3295/**
3296 * sys_rt_sigaction - alter an action taken by a process
3297 * @sig: signal to be sent
3298 * @act: new sigaction
3299 * @oact: used to save the previous sigaction
3300 * @sigsetsize: size of sigset_t type
3301 */
3302SYSCALL_DEFINE4(rt_sigaction, int, sig,
3303 const struct sigaction __user *, act,
3304 struct sigaction __user *, oact,
3305 size_t, sigsetsize)
3306{
3307 struct k_sigaction new_sa, old_sa;
3308 int ret = -EINVAL;
3309
3310 /* XXX: Don't preclude handling different sized sigset_t's. */
3311 if (sigsetsize != sizeof(sigset_t))
3312 goto out;
3313
3314 if (act) {
3315 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3316 return -EFAULT;
3317 }
3318
3319 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3320
3321 if (!ret && oact) {
3322 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3323 return -EFAULT;
3324 }
3325out:
3326 return ret;
3327}
3328#ifdef CONFIG_COMPAT
3329COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3330 const struct compat_sigaction __user *, act,
3331 struct compat_sigaction __user *, oact,
3332 compat_size_t, sigsetsize)
3333{
3334 struct k_sigaction new_ka, old_ka;
3335 compat_sigset_t mask;
3336#ifdef __ARCH_HAS_SA_RESTORER
3337 compat_uptr_t restorer;
3338#endif
3339 int ret;
3340
3341 /* XXX: Don't preclude handling different sized sigset_t's. */
3342 if (sigsetsize != sizeof(compat_sigset_t))
3343 return -EINVAL;
3344
3345 if (act) {
3346 compat_uptr_t handler;
3347 ret = get_user(handler, &act->sa_handler);
3348 new_ka.sa.sa_handler = compat_ptr(handler);
3349#ifdef __ARCH_HAS_SA_RESTORER
3350 ret |= get_user(restorer, &act->sa_restorer);
3351 new_ka.sa.sa_restorer = compat_ptr(restorer);
3352#endif
3353 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3354 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3355 if (ret)
3356 return -EFAULT;
3357 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3358 }
3359
3360 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3361 if (!ret && oact) {
3362 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3363 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3364 &oact->sa_handler);
3365 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3366 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3367#ifdef __ARCH_HAS_SA_RESTORER
3368 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3369 &oact->sa_restorer);
3370#endif
3371 }
3372 return ret;
3373}
3374#endif
3375#endif /* !CONFIG_ODD_RT_SIGACTION */
3376
3377#ifdef CONFIG_OLD_SIGACTION
3378SYSCALL_DEFINE3(sigaction, int, sig,
3379 const struct old_sigaction __user *, act,
3380 struct old_sigaction __user *, oact)
3381{
3382 struct k_sigaction new_ka, old_ka;
3383 int ret;
3384
3385 if (act) {
3386 old_sigset_t mask;
3387 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3388 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3389 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3390 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3391 __get_user(mask, &act->sa_mask))
3392 return -EFAULT;
3393#ifdef __ARCH_HAS_KA_RESTORER
3394 new_ka.ka_restorer = NULL;
3395#endif
3396 siginitset(&new_ka.sa.sa_mask, mask);
3397 }
3398
3399 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3400
3401 if (!ret && oact) {
3402 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3403 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3404 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3405 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3406 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3407 return -EFAULT;
3408 }
3409
3410 return ret;
3411}
3412#endif
3413#ifdef CONFIG_COMPAT_OLD_SIGACTION
3414COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3415 const struct compat_old_sigaction __user *, act,
3416 struct compat_old_sigaction __user *, oact)
3417{
3418 struct k_sigaction new_ka, old_ka;
3419 int ret;
3420 compat_old_sigset_t mask;
3421 compat_uptr_t handler, restorer;
3422
3423 if (act) {
3424 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3425 __get_user(handler, &act->sa_handler) ||
3426 __get_user(restorer, &act->sa_restorer) ||
3427 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3428 __get_user(mask, &act->sa_mask))
3429 return -EFAULT;
3430
3431#ifdef __ARCH_HAS_KA_RESTORER
3432 new_ka.ka_restorer = NULL;
3433#endif
3434 new_ka.sa.sa_handler = compat_ptr(handler);
3435 new_ka.sa.sa_restorer = compat_ptr(restorer);
3436 siginitset(&new_ka.sa.sa_mask, mask);
3437 }
3438
3439 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3440
3441 if (!ret && oact) {
3442 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3443 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3444 &oact->sa_handler) ||
3445 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3446 &oact->sa_restorer) ||
3447 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3448 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3449 return -EFAULT;
3450 }
3451 return ret;
3452}
3453#endif
3454
3455#ifdef CONFIG_SGETMASK_SYSCALL
3456
3457/*
3458 * For backwards compatibility. Functionality superseded by sigprocmask.
3459 */
3460SYSCALL_DEFINE0(sgetmask)
3461{
3462 /* SMP safe */
3463 return current->blocked.sig[0];
3464}
3465
3466SYSCALL_DEFINE1(ssetmask, int, newmask)
3467{
3468 int old = current->blocked.sig[0];
3469 sigset_t newset;
3470
3471 siginitset(&newset, newmask);
3472 set_current_blocked(&newset);
3473
3474 return old;
3475}
3476#endif /* CONFIG_SGETMASK_SYSCALL */
3477
3478#ifdef __ARCH_WANT_SYS_SIGNAL
3479/*
3480 * For backwards compatibility. Functionality superseded by sigaction.
3481 */
3482SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3483{
3484 struct k_sigaction new_sa, old_sa;
3485 int ret;
3486
3487 new_sa.sa.sa_handler = handler;
3488 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3489 sigemptyset(&new_sa.sa.sa_mask);
3490
3491 ret = do_sigaction(sig, &new_sa, &old_sa);
3492
3493 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3494}
3495#endif /* __ARCH_WANT_SYS_SIGNAL */
3496
3497#ifdef __ARCH_WANT_SYS_PAUSE
3498
3499SYSCALL_DEFINE0(pause)
3500{
3501 while (!signal_pending(current)) {
3502 __set_current_state(TASK_INTERRUPTIBLE);
3503 schedule();
3504 }
3505 return -ERESTARTNOHAND;
3506}
3507
3508#endif
3509
3510static int sigsuspend(sigset_t *set)
3511{
3512 current->saved_sigmask = current->blocked;
3513 set_current_blocked(set);
3514
3515 while (!signal_pending(current)) {
3516 __set_current_state(TASK_INTERRUPTIBLE);
3517 schedule();
3518 }
3519 set_restore_sigmask();
3520 return -ERESTARTNOHAND;
3521}
3522
3523/**
3524 * sys_rt_sigsuspend - replace the signal mask for a value with the
3525 * @unewset value until a signal is received
3526 * @unewset: new signal mask value
3527 * @sigsetsize: size of sigset_t type
3528 */
3529SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3530{
3531 sigset_t newset;
3532
3533 /* XXX: Don't preclude handling different sized sigset_t's. */
3534 if (sigsetsize != sizeof(sigset_t))
3535 return -EINVAL;
3536
3537 if (copy_from_user(&newset, unewset, sizeof(newset)))
3538 return -EFAULT;
3539 return sigsuspend(&newset);
3540}
3541
3542#ifdef CONFIG_COMPAT
3543COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3544{
3545#ifdef __BIG_ENDIAN
3546 sigset_t newset;
3547 compat_sigset_t newset32;
3548
3549 /* XXX: Don't preclude handling different sized sigset_t's. */
3550 if (sigsetsize != sizeof(sigset_t))
3551 return -EINVAL;
3552
3553 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3554 return -EFAULT;
3555 sigset_from_compat(&newset, &newset32);
3556 return sigsuspend(&newset);
3557#else
3558 /* on little-endian bitmaps don't care about granularity */
3559 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3560#endif
3561}
3562#endif
3563
3564#ifdef CONFIG_OLD_SIGSUSPEND
3565SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3566{
3567 sigset_t blocked;
3568 siginitset(&blocked, mask);
3569 return sigsuspend(&blocked);
3570}
3571#endif
3572#ifdef CONFIG_OLD_SIGSUSPEND3
3573SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3574{
3575 sigset_t blocked;
3576 siginitset(&blocked, mask);
3577 return sigsuspend(&blocked);
3578}
3579#endif
3580
3581__weak const char *arch_vma_name(struct vm_area_struct *vma)
3582{
3583 return NULL;
3584}
3585
3586void __init signals_init(void)
3587{
3588 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3589 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3590 != offsetof(struct siginfo, _sifields._pad));
3591
3592 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3593}
3594
3595#ifdef CONFIG_KGDB_KDB
3596#include <linux/kdb.h>
3597/*
3598 * kdb_send_sig_info - Allows kdb to send signals without exposing
3599 * signal internals. This function checks if the required locks are
3600 * available before calling the main signal code, to avoid kdb
3601 * deadlocks.
3602 */
3603void
3604kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3605{
3606 static struct task_struct *kdb_prev_t;
3607 int sig, new_t;
3608 if (!spin_trylock(&t->sighand->siglock)) {
3609 kdb_printf("Can't do kill command now.\n"
3610 "The sigmask lock is held somewhere else in "
3611 "kernel, try again later\n");
3612 return;
3613 }
3614 spin_unlock(&t->sighand->siglock);
3615 new_t = kdb_prev_t != t;
3616 kdb_prev_t = t;
3617 if (t->state != TASK_RUNNING && new_t) {
3618 kdb_printf("Process is not RUNNING, sending a signal from "
3619 "kdb risks deadlock\n"
3620 "on the run queue locks. "
3621 "The signal has _not_ been sent.\n"
3622 "Reissue the kill command if you want to risk "
3623 "the deadlock.\n");
3624 return;
3625 }
3626 sig = info->si_signo;
3627 if (send_sig_info(sig, info, t))
3628 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3629 sig, t->pid);
3630 else
3631 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3632}
3633#endif /* CONFIG_KGDB_KDB */