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