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(set: &t->blocked, sig: sig) || sigismember(set: &t->real_blocked, sig: 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(task: t)) {
165 set_tsk_thread_flag(tsk: 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 if (unlikely(test_thread_flag(TIF_SIGPENDING)))
181 clear_thread_flag(TIF_SIGPENDING);
182 }
183}
184EXPORT_SYMBOL(recalc_sigpending);
185
186void calculate_sigpending(void)
187{
188 /* Have any signals or users of TIF_SIGPENDING been delayed
189 * until after fork?
190 */
191 spin_lock_irq(lock: &current->sighand->siglock);
192 set_tsk_thread_flag(current, TIF_SIGPENDING);
193 recalc_sigpending();
194 spin_unlock_irq(lock: &current->sighand->siglock);
195}
196
197/* Given the mask, find the first available signal that should be serviced. */
198
199#define SYNCHRONOUS_MASK \
200 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
201 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
202
203int next_signal(struct sigpending *pending, sigset_t *mask)
204{
205 unsigned long i, *s, *m, x;
206 int sig = 0;
207
208 s = pending->signal.sig;
209 m = mask->sig;
210
211 /*
212 * Handle the first word specially: it contains the
213 * synchronous signals that need to be dequeued first.
214 */
215 x = *s &~ *m;
216 if (x) {
217 if (x & SYNCHRONOUS_MASK)
218 x &= SYNCHRONOUS_MASK;
219 sig = ffz(~x) + 1;
220 return sig;
221 }
222
223 switch (_NSIG_WORDS) {
224 default:
225 for (i = 1; i < _NSIG_WORDS; ++i) {
226 x = *++s &~ *++m;
227 if (!x)
228 continue;
229 sig = ffz(~x) + i*_NSIG_BPW + 1;
230 break;
231 }
232 break;
233
234 case 2:
235 x = s[1] &~ m[1];
236 if (!x)
237 break;
238 sig = ffz(~x) + _NSIG_BPW + 1;
239 break;
240
241 case 1:
242 /* Nothing to do */
243 break;
244 }
245
246 return sig;
247}
248
249static inline void print_dropped_signal(int sig)
250{
251 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
252
253 if (!print_fatal_signals)
254 return;
255
256 if (!__ratelimit(&ratelimit_state))
257 return;
258
259 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
260 current->comm, current->pid, sig);
261}
262
263/**
264 * task_set_jobctl_pending - set jobctl pending bits
265 * @task: target task
266 * @mask: pending bits to set
267 *
268 * Clear @mask from @task->jobctl. @mask must be subset of
269 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
270 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
271 * cleared. If @task is already being killed or exiting, this function
272 * becomes noop.
273 *
274 * CONTEXT:
275 * Must be called with @task->sighand->siglock held.
276 *
277 * RETURNS:
278 * %true if @mask is set, %false if made noop because @task was dying.
279 */
280bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
281{
282 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
283 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
284 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
285
286 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
287 return false;
288
289 if (mask & JOBCTL_STOP_SIGMASK)
290 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
291
292 task->jobctl |= mask;
293 return true;
294}
295
296/**
297 * task_clear_jobctl_trapping - clear jobctl trapping bit
298 * @task: target task
299 *
300 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
301 * Clear it and wake up the ptracer. Note that we don't need any further
302 * locking. @task->siglock guarantees that @task->parent points to the
303 * ptracer.
304 *
305 * CONTEXT:
306 * Must be called with @task->sighand->siglock held.
307 */
308void task_clear_jobctl_trapping(struct task_struct *task)
309{
310 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
311 task->jobctl &= ~JOBCTL_TRAPPING;
312 smp_mb(); /* advised by wake_up_bit() */
313 wake_up_bit(word: &task->jobctl, JOBCTL_TRAPPING_BIT);
314 }
315}
316
317/**
318 * task_clear_jobctl_pending - clear jobctl pending bits
319 * @task: target task
320 * @mask: pending bits to clear
321 *
322 * Clear @mask from @task->jobctl. @mask must be subset of
323 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
324 * STOP bits are cleared together.
325 *
326 * If clearing of @mask leaves no stop or trap pending, this function calls
327 * task_clear_jobctl_trapping().
328 *
329 * CONTEXT:
330 * Must be called with @task->sighand->siglock held.
331 */
332void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
333{
334 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
335
336 if (mask & JOBCTL_STOP_PENDING)
337 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
338
339 task->jobctl &= ~mask;
340
341 if (!(task->jobctl & JOBCTL_PENDING_MASK))
342 task_clear_jobctl_trapping(task);
343}
344
345/**
346 * task_participate_group_stop - participate in a group stop
347 * @task: task participating in a group stop
348 *
349 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
350 * Group stop states are cleared and the group stop count is consumed if
351 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
352 * stop, the appropriate `SIGNAL_*` flags are set.
353 *
354 * CONTEXT:
355 * Must be called with @task->sighand->siglock held.
356 *
357 * RETURNS:
358 * %true if group stop completion should be notified to the parent, %false
359 * otherwise.
360 */
361static bool task_participate_group_stop(struct task_struct *task)
362{
363 struct signal_struct *sig = task->signal;
364 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
365
366 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
367
368 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
369
370 if (!consume)
371 return false;
372
373 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
374 sig->group_stop_count--;
375
376 /*
377 * Tell the caller to notify completion iff we are entering into a
378 * fresh group stop. Read comment in do_signal_stop() for details.
379 */
380 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
381 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
382 return true;
383 }
384 return false;
385}
386
387void task_join_group_stop(struct task_struct *task)
388{
389 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
390 struct signal_struct *sig = current->signal;
391
392 if (sig->group_stop_count) {
393 sig->group_stop_count++;
394 mask |= JOBCTL_STOP_CONSUME;
395 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
396 return;
397
398 /* Have the new thread join an on-going signal group stop */
399 task_set_jobctl_pending(task, mask: mask | JOBCTL_STOP_PENDING);
400}
401
402static struct ucounts *sig_get_ucounts(struct task_struct *t, int sig,
403 int override_rlimit)
404{
405 struct ucounts *ucounts;
406 long sigpending;
407
408 /*
409 * Protect access to @t credentials. This can go away when all
410 * callers hold rcu read lock.
411 *
412 * NOTE! A pending signal will hold on to the user refcount,
413 * and we get/put the refcount only when the sigpending count
414 * changes from/to zero.
415 */
416 rcu_read_lock();
417 ucounts = task_ucounts(t);
418 sigpending = inc_rlimit_get_ucounts(ucounts, type: UCOUNT_RLIMIT_SIGPENDING,
419 override_rlimit);
420 rcu_read_unlock();
421 if (!sigpending)
422 return NULL;
423
424 if (unlikely(!override_rlimit && sigpending > task_rlimit(t, RLIMIT_SIGPENDING))) {
425 dec_rlimit_put_ucounts(ucounts, type: UCOUNT_RLIMIT_SIGPENDING);
426 print_dropped_signal(sig);
427 return NULL;
428 }
429
430 return ucounts;
431}
432
433static void __sigqueue_init(struct sigqueue *q, struct ucounts *ucounts,
434 const unsigned int sigqueue_flags)
435{
436 INIT_LIST_HEAD(list: &q->list);
437 q->flags = sigqueue_flags;
438 q->ucounts = ucounts;
439}
440
441/*
442 * allocate a new signal queue record
443 * - this may be called without locks if and only if t == current, otherwise an
444 * appropriate lock must be held to stop the target task from exiting
445 */
446static struct sigqueue *sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
447 int override_rlimit)
448{
449 struct ucounts *ucounts = sig_get_ucounts(t, sig, override_rlimit);
450 struct sigqueue *q;
451
452 if (!ucounts)
453 return NULL;
454
455 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
456 if (!q) {
457 dec_rlimit_put_ucounts(ucounts, type: UCOUNT_RLIMIT_SIGPENDING);
458 return NULL;
459 }
460
461 __sigqueue_init(q, ucounts, sigqueue_flags: 0);
462 return q;
463}
464
465static void __sigqueue_free(struct sigqueue *q)
466{
467 if (q->flags & SIGQUEUE_PREALLOC) {
468 posixtimer_sigqueue_putref(q);
469 return;
470 }
471 if (q->ucounts) {
472 dec_rlimit_put_ucounts(ucounts: q->ucounts, type: UCOUNT_RLIMIT_SIGPENDING);
473 q->ucounts = NULL;
474 }
475 kmem_cache_free(s: sigqueue_cachep, objp: q);
476}
477
478void flush_sigqueue(struct sigpending *queue)
479{
480 struct sigqueue *q;
481
482 sigemptyset(set: &queue->signal);
483 while (!list_empty(head: &queue->list)) {
484 q = list_entry(queue->list.next, struct sigqueue , list);
485 list_del_init(entry: &q->list);
486 __sigqueue_free(q);
487 }
488}
489
490/*
491 * Flush all pending signals for this kthread.
492 */
493void flush_signals(struct task_struct *t)
494{
495 unsigned long flags;
496
497 spin_lock_irqsave(&t->sighand->siglock, flags);
498 clear_tsk_thread_flag(tsk: t, TIF_SIGPENDING);
499 flush_sigqueue(queue: &t->pending);
500 flush_sigqueue(queue: &t->signal->shared_pending);
501 spin_unlock_irqrestore(lock: &t->sighand->siglock, flags);
502}
503EXPORT_SYMBOL(flush_signals);
504
505void ignore_signals(struct task_struct *t)
506{
507 int i;
508
509 for (i = 0; i < _NSIG; ++i)
510 t->sighand->action[i].sa.sa_handler = SIG_IGN;
511
512 flush_signals(t);
513}
514
515/*
516 * Flush all handlers for a task.
517 */
518
519void
520flush_signal_handlers(struct task_struct *t, int force_default)
521{
522 int i;
523 struct k_sigaction *ka = &t->sighand->action[0];
524 for (i = _NSIG ; i != 0 ; i--) {
525 if (force_default || ka->sa.sa_handler != SIG_IGN)
526 ka->sa.sa_handler = SIG_DFL;
527 ka->sa.sa_flags = 0;
528#ifdef __ARCH_HAS_SA_RESTORER
529 ka->sa.sa_restorer = NULL;
530#endif
531 sigemptyset(set: &ka->sa.sa_mask);
532 ka++;
533 }
534}
535
536bool unhandled_signal(struct task_struct *tsk, int sig)
537{
538 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
539 if (is_global_init(tsk))
540 return true;
541
542 if (handler != SIG_IGN && handler != SIG_DFL)
543 return false;
544
545 /* If dying, we handle all new signals by ignoring them */
546 if (fatal_signal_pending(p: tsk))
547 return false;
548
549 /* if ptraced, let the tracer determine */
550 return !tsk->ptrace;
551}
552
553static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
554 struct sigqueue **timer_sigq)
555{
556 struct sigqueue *q, *first = NULL;
557
558 /*
559 * Collect the siginfo appropriate to this signal. Check if
560 * there is another siginfo for the same signal.
561 */
562 list_for_each_entry(q, &list->list, list) {
563 if (q->info.si_signo == sig) {
564 if (first)
565 goto still_pending;
566 first = q;
567 }
568 }
569
570 sigdelset(set: &list->signal, sig: sig);
571
572 if (first) {
573still_pending:
574 list_del_init(entry: &first->list);
575 copy_siginfo(to: info, from: &first->info);
576
577 /*
578 * posix-timer signals are preallocated and freed when the last
579 * reference count is dropped in posixtimer_deliver_signal() or
580 * immediately on timer deletion when the signal is not pending.
581 * Spare the extra round through __sigqueue_free() which is
582 * ignoring preallocated signals.
583 */
584 if (unlikely((first->flags & SIGQUEUE_PREALLOC) && (info->si_code == SI_TIMER)))
585 *timer_sigq = first;
586 else
587 __sigqueue_free(q: first);
588 } else {
589 /*
590 * Ok, it wasn't in the queue. This must be
591 * a fast-pathed signal or we must have been
592 * out of queue space. So zero out the info.
593 */
594 clear_siginfo(info);
595 info->si_signo = sig;
596 info->si_errno = 0;
597 info->si_code = SI_USER;
598 info->si_pid = 0;
599 info->si_uid = 0;
600 }
601}
602
603static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
604 kernel_siginfo_t *info, struct sigqueue **timer_sigq)
605{
606 int sig = next_signal(pending, mask);
607
608 if (sig)
609 collect_signal(sig, list: pending, info, timer_sigq);
610 return sig;
611}
612
613/*
614 * Try to dequeue a signal. If a deliverable signal is found fill in the
615 * caller provided siginfo and return the signal number. Otherwise return
616 * 0.
617 */
618int dequeue_signal(sigset_t *mask, kernel_siginfo_t *info, enum pid_type *type)
619{
620 struct task_struct *tsk = current;
621 struct sigqueue *timer_sigq;
622 int signr;
623
624 lockdep_assert_held(&tsk->sighand->siglock);
625
626again:
627 *type = PIDTYPE_PID;
628 timer_sigq = NULL;
629 signr = __dequeue_signal(pending: &tsk->pending, mask, info, timer_sigq: &timer_sigq);
630 if (!signr) {
631 *type = PIDTYPE_TGID;
632 signr = __dequeue_signal(pending: &tsk->signal->shared_pending,
633 mask, info, timer_sigq: &timer_sigq);
634
635 if (unlikely(signr == SIGALRM))
636 posixtimer_rearm_itimer(p: tsk);
637 }
638
639 recalc_sigpending();
640 if (!signr)
641 return 0;
642
643 if (unlikely(sig_kernel_stop(signr))) {
644 /*
645 * Set a marker that we have dequeued a stop signal. Our
646 * caller might release the siglock and then the pending
647 * stop signal it is about to process is no longer in the
648 * pending bitmasks, but must still be cleared by a SIGCONT
649 * (and overruled by a SIGKILL). So those cases clear this
650 * shared flag after we've set it. Note that this flag may
651 * remain set after the signal we return is ignored or
652 * handled. That doesn't matter because its only purpose
653 * is to alert stop-signal processing code when another
654 * processor has come along and cleared the flag.
655 */
656 current->jobctl |= JOBCTL_STOP_DEQUEUED;
657 }
658
659 if (IS_ENABLED(CONFIG_POSIX_TIMERS) && unlikely(timer_sigq)) {
660 if (!posixtimer_deliver_signal(info, timer_sigq))
661 goto again;
662 }
663
664 return signr;
665}
666EXPORT_SYMBOL_GPL(dequeue_signal);
667
668static int dequeue_synchronous_signal(kernel_siginfo_t *info)
669{
670 struct task_struct *tsk = current;
671 struct sigpending *pending = &tsk->pending;
672 struct sigqueue *q, *sync = NULL;
673
674 /*
675 * Might a synchronous signal be in the queue?
676 */
677 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
678 return 0;
679
680 /*
681 * Return the first synchronous signal in the queue.
682 */
683 list_for_each_entry(q, &pending->list, list) {
684 /* Synchronous signals have a positive si_code */
685 if ((q->info.si_code > SI_USER) &&
686 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
687 sync = q;
688 goto next;
689 }
690 }
691 return 0;
692next:
693 /*
694 * Check if there is another siginfo for the same signal.
695 */
696 list_for_each_entry_continue(q, &pending->list, list) {
697 if (q->info.si_signo == sync->info.si_signo)
698 goto still_pending;
699 }
700
701 sigdelset(set: &pending->signal, sig: sync->info.si_signo);
702 recalc_sigpending();
703still_pending:
704 list_del_init(entry: &sync->list);
705 copy_siginfo(to: info, from: &sync->info);
706 __sigqueue_free(q: sync);
707 return info->si_signo;
708}
709
710/*
711 * Tell a process that it has a new active signal..
712 *
713 * NOTE! we rely on the previous spin_lock to
714 * lock interrupts for us! We can only be called with
715 * "siglock" held, and the local interrupt must
716 * have been disabled when that got acquired!
717 *
718 * No need to set need_resched since signal event passing
719 * goes through ->blocked
720 */
721void signal_wake_up_state(struct task_struct *t, unsigned int state)
722{
723 lockdep_assert_held(&t->sighand->siglock);
724
725 set_tsk_thread_flag(tsk: t, TIF_SIGPENDING);
726
727 /*
728 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
729 * case. We don't check t->state here because there is a race with it
730 * executing another processor and just now entering stopped state.
731 * By using wake_up_state, we ensure the process will wake up and
732 * handle its death signal.
733 */
734 if (!wake_up_state(tsk: t, state: state | TASK_INTERRUPTIBLE))
735 kick_process(tsk: t);
736}
737
738static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q);
739
740static void sigqueue_free_ignored(struct task_struct *tsk, struct sigqueue *q)
741{
742 if (likely(!(q->flags & SIGQUEUE_PREALLOC) || q->info.si_code != SI_TIMER))
743 __sigqueue_free(q);
744 else
745 posixtimer_sig_ignore(tsk, q);
746}
747
748/* Remove signals in mask from the pending set and queue. */
749static void flush_sigqueue_mask(struct task_struct *p, sigset_t *mask, struct sigpending *s)
750{
751 struct sigqueue *q, *n;
752 sigset_t m;
753
754 lockdep_assert_held(&p->sighand->siglock);
755
756 sigandsets(r: &m, a: mask, b: &s->signal);
757 if (sigisemptyset(set: &m))
758 return;
759
760 sigandnsets(r: &s->signal, a: &s->signal, b: mask);
761 list_for_each_entry_safe(q, n, &s->list, list) {
762 if (sigismember(set: mask, sig: q->info.si_signo)) {
763 list_del_init(entry: &q->list);
764 sigqueue_free_ignored(tsk: p, q);
765 }
766 }
767}
768
769static inline int is_si_special(const struct kernel_siginfo *info)
770{
771 return info <= SEND_SIG_PRIV;
772}
773
774static inline bool si_fromuser(const struct kernel_siginfo *info)
775{
776 return info == SEND_SIG_NOINFO ||
777 (!is_si_special(info) && SI_FROMUSER(info));
778}
779
780/*
781 * called with RCU read lock from check_kill_permission()
782 */
783static bool kill_ok_by_cred(struct task_struct *t)
784{
785 const struct cred *cred = current_cred();
786 const struct cred *tcred = __task_cred(t);
787
788 return uid_eq(left: cred->euid, right: tcred->suid) ||
789 uid_eq(left: cred->euid, right: tcred->uid) ||
790 uid_eq(left: cred->uid, right: tcred->suid) ||
791 uid_eq(left: cred->uid, right: tcred->uid) ||
792 ns_capable(ns: tcred->user_ns, CAP_KILL);
793}
794
795/*
796 * Bad permissions for sending the signal
797 * - the caller must hold the RCU read lock
798 */
799static int check_kill_permission(int sig, struct kernel_siginfo *info,
800 struct task_struct *t)
801{
802 struct pid *sid;
803 int error;
804
805 if (!valid_signal(sig))
806 return -EINVAL;
807
808 if (!si_fromuser(info))
809 return 0;
810
811 error = audit_signal_info(sig, t); /* Let audit system see the signal */
812 if (error)
813 return error;
814
815 if (!same_thread_group(current, p2: t) &&
816 !kill_ok_by_cred(t)) {
817 switch (sig) {
818 case SIGCONT:
819 sid = task_session(task: t);
820 /*
821 * We don't return the error if sid == NULL. The
822 * task was unhashed, the caller must notice this.
823 */
824 if (!sid || sid == task_session(current))
825 break;
826 fallthrough;
827 default:
828 return -EPERM;
829 }
830 }
831
832 return security_task_kill(p: t, info, sig, NULL);
833}
834
835/**
836 * ptrace_trap_notify - schedule trap to notify ptracer
837 * @t: tracee wanting to notify tracer
838 *
839 * This function schedules sticky ptrace trap which is cleared on the next
840 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
841 * ptracer.
842 *
843 * If @t is running, STOP trap will be taken. If trapped for STOP and
844 * ptracer is listening for events, tracee is woken up so that it can
845 * re-trap for the new event. If trapped otherwise, STOP trap will be
846 * eventually taken without returning to userland after the existing traps
847 * are finished by PTRACE_CONT.
848 *
849 * CONTEXT:
850 * Must be called with @task->sighand->siglock held.
851 */
852static void ptrace_trap_notify(struct task_struct *t)
853{
854 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
855 lockdep_assert_held(&t->sighand->siglock);
856
857 task_set_jobctl_pending(task: t, JOBCTL_TRAP_NOTIFY);
858 ptrace_signal_wake_up(t, resume: t->jobctl & JOBCTL_LISTENING);
859}
860
861/*
862 * Handle magic process-wide effects of stop/continue signals. Unlike
863 * the signal actions, these happen immediately at signal-generation
864 * time regardless of blocking, ignoring, or handling. This does the
865 * actual continuing for SIGCONT, but not the actual stopping for stop
866 * signals. The process stop is done as a signal action for SIG_DFL.
867 *
868 * Returns true if the signal should be actually delivered, otherwise
869 * it should be dropped.
870 */
871static bool prepare_signal(int sig, struct task_struct *p, bool force)
872{
873 struct signal_struct *signal = p->signal;
874 struct task_struct *t;
875 sigset_t flush;
876
877 if (signal->flags & SIGNAL_GROUP_EXIT) {
878 if (signal->core_state)
879 return sig == SIGKILL;
880 /*
881 * The process is in the middle of dying, drop the signal.
882 */
883 return false;
884 } else if (sig_kernel_stop(sig)) {
885 /*
886 * This is a stop signal. Remove SIGCONT from all queues.
887 */
888 siginitset(set: &flush, sigmask(SIGCONT));
889 flush_sigqueue_mask(p, mask: &flush, s: &signal->shared_pending);
890 for_each_thread(p, t)
891 flush_sigqueue_mask(p, mask: &flush, s: &t->pending);
892 } else if (sig == SIGCONT) {
893 unsigned int why;
894 /*
895 * Remove all stop signals from all queues, wake all threads.
896 */
897 siginitset(set: &flush, SIG_KERNEL_STOP_MASK);
898 flush_sigqueue_mask(p, mask: &flush, s: &signal->shared_pending);
899 for_each_thread(p, t) {
900 flush_sigqueue_mask(p, mask: &flush, s: &t->pending);
901 task_clear_jobctl_pending(task: t, JOBCTL_STOP_PENDING);
902 if (likely(!(t->ptrace & PT_SEIZED))) {
903 t->jobctl &= ~JOBCTL_STOPPED;
904 wake_up_state(tsk: t, __TASK_STOPPED);
905 } else
906 ptrace_trap_notify(t);
907 }
908
909 /*
910 * Notify the parent with CLD_CONTINUED if we were stopped.
911 *
912 * If we were in the middle of a group stop, we pretend it
913 * was already finished, and then continued. Since SIGCHLD
914 * doesn't queue we report only CLD_STOPPED, as if the next
915 * CLD_CONTINUED was dropped.
916 */
917 why = 0;
918 if (signal->flags & SIGNAL_STOP_STOPPED)
919 why |= SIGNAL_CLD_CONTINUED;
920 else if (signal->group_stop_count)
921 why |= SIGNAL_CLD_STOPPED;
922
923 if (why) {
924 /*
925 * The first thread which returns from do_signal_stop()
926 * will take ->siglock, notice SIGNAL_CLD_MASK, and
927 * notify its parent. See get_signal().
928 */
929 signal_set_stop_flags(sig: signal, flags: why | SIGNAL_STOP_CONTINUED);
930 signal->group_stop_count = 0;
931 signal->group_exit_code = 0;
932 }
933 }
934
935 return !sig_ignored(t: p, sig, force);
936}
937
938/*
939 * Test if P wants to take SIG. After we've checked all threads with this,
940 * it's equivalent to finding no threads not blocking SIG. Any threads not
941 * blocking SIG were ruled out because they are not running and already
942 * have pending signals. Such threads will dequeue from the shared queue
943 * as soon as they're available, so putting the signal on the shared queue
944 * will be equivalent to sending it to one such thread.
945 */
946static inline bool wants_signal(int sig, struct task_struct *p)
947{
948 if (sigismember(set: &p->blocked, sig: sig))
949 return false;
950
951 if (p->flags & PF_EXITING)
952 return false;
953
954 if (sig == SIGKILL)
955 return true;
956
957 if (task_is_stopped_or_traced(p))
958 return false;
959
960 return task_curr(p) || !task_sigpending(p);
961}
962
963static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
964{
965 struct signal_struct *signal = p->signal;
966 struct task_struct *t;
967
968 /*
969 * Now find a thread we can wake up to take the signal off the queue.
970 *
971 * Try the suggested task first (may or may not be the main thread).
972 */
973 if (wants_signal(sig, p))
974 t = p;
975 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
976 /*
977 * There is just one thread and it does not need to be woken.
978 * It will dequeue unblocked signals before it runs again.
979 */
980 return;
981 else {
982 /*
983 * Otherwise try to find a suitable thread.
984 */
985 t = signal->curr_target;
986 while (!wants_signal(sig, p: t)) {
987 t = next_thread(p: t);
988 if (t == signal->curr_target)
989 /*
990 * No thread needs to be woken.
991 * Any eligible threads will see
992 * the signal in the queue soon.
993 */
994 return;
995 }
996 signal->curr_target = t;
997 }
998
999 /*
1000 * Found a killable thread. If the signal will be fatal,
1001 * then start taking the whole group down immediately.
1002 */
1003 if (sig_fatal(p, sig) &&
1004 (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1005 !sigismember(set: &t->real_blocked, sig: sig) &&
1006 (sig == SIGKILL || !p->ptrace)) {
1007 /*
1008 * This signal will be fatal to the whole group.
1009 */
1010 if (!sig_kernel_coredump(sig)) {
1011 /*
1012 * Start a group exit and wake everybody up.
1013 * This way we don't have other threads
1014 * running and doing things after a slower
1015 * thread has the fatal signal pending.
1016 */
1017 signal->flags = SIGNAL_GROUP_EXIT;
1018 signal->group_exit_code = sig;
1019 signal->group_stop_count = 0;
1020 __for_each_thread(signal, t) {
1021 task_clear_jobctl_pending(task: t, JOBCTL_PENDING_MASK);
1022 sigaddset(set: &t->pending.signal, SIGKILL);
1023 signal_wake_up(t, fatal: 1);
1024 }
1025 return;
1026 }
1027 }
1028
1029 /*
1030 * The signal is already in the shared-pending queue.
1031 * Tell the chosen thread to wake up and dequeue it.
1032 */
1033 signal_wake_up(t, fatal: sig == SIGKILL);
1034 return;
1035}
1036
1037static inline bool legacy_queue(struct sigpending *signals, int sig)
1038{
1039 return (sig < SIGRTMIN) && sigismember(set: &signals->signal, sig: sig);
1040}
1041
1042static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1043 struct task_struct *t, enum pid_type type, bool force)
1044{
1045 struct sigpending *pending;
1046 struct sigqueue *q;
1047 int override_rlimit;
1048 int ret = 0, result;
1049
1050 lockdep_assert_held(&t->sighand->siglock);
1051
1052 result = TRACE_SIGNAL_IGNORED;
1053 if (!prepare_signal(sig, p: t, force))
1054 goto ret;
1055
1056 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1057 /*
1058 * Short-circuit ignored signals and support queuing
1059 * exactly one non-rt signal, so that we can get more
1060 * detailed information about the cause of the signal.
1061 */
1062 result = TRACE_SIGNAL_ALREADY_PENDING;
1063 if (legacy_queue(signals: pending, sig))
1064 goto ret;
1065
1066 result = TRACE_SIGNAL_DELIVERED;
1067 /*
1068 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1069 */
1070 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1071 goto out_set;
1072
1073 /*
1074 * Real-time signals must be queued if sent by sigqueue, or
1075 * some other real-time mechanism. It is implementation
1076 * defined whether kill() does so. We attempt to do so, on
1077 * the principle of least surprise, but since kill is not
1078 * allowed to fail with EAGAIN when low on memory we just
1079 * make sure at least one signal gets delivered and don't
1080 * pass on the info struct.
1081 */
1082 if (sig < SIGRTMIN)
1083 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1084 else
1085 override_rlimit = 0;
1086
1087 q = sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1088
1089 if (q) {
1090 list_add_tail(new: &q->list, head: &pending->list);
1091 switch ((unsigned long) info) {
1092 case (unsigned long) SEND_SIG_NOINFO:
1093 clear_siginfo(info: &q->info);
1094 q->info.si_signo = sig;
1095 q->info.si_errno = 0;
1096 q->info.si_code = SI_USER;
1097 q->info.si_pid = task_tgid_nr_ns(current,
1098 ns: task_active_pid_ns(tsk: t));
1099 rcu_read_lock();
1100 q->info.si_uid =
1101 from_kuid_munged(task_cred_xxx(t, user_ns),
1102 current_uid());
1103 rcu_read_unlock();
1104 break;
1105 case (unsigned long) SEND_SIG_PRIV:
1106 clear_siginfo(info: &q->info);
1107 q->info.si_signo = sig;
1108 q->info.si_errno = 0;
1109 q->info.si_code = SI_KERNEL;
1110 q->info.si_pid = 0;
1111 q->info.si_uid = 0;
1112 break;
1113 default:
1114 copy_siginfo(to: &q->info, from: info);
1115 break;
1116 }
1117 } else if (!is_si_special(info) &&
1118 sig >= SIGRTMIN && info->si_code != SI_USER) {
1119 /*
1120 * Queue overflow, abort. We may abort if the
1121 * signal was rt and sent by user using something
1122 * other than kill().
1123 */
1124 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1125 ret = -EAGAIN;
1126 goto ret;
1127 } else {
1128 /*
1129 * This is a silent loss of information. We still
1130 * send the signal, but the *info bits are lost.
1131 */
1132 result = TRACE_SIGNAL_LOSE_INFO;
1133 }
1134
1135out_set:
1136 signalfd_notify(tsk: t, sig);
1137 sigaddset(set: &pending->signal, sig: sig);
1138
1139 /* Let multiprocess signals appear after on-going forks */
1140 if (type > PIDTYPE_TGID) {
1141 struct multiprocess_signals *delayed;
1142 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1143 sigset_t *signal = &delayed->signal;
1144 /* Can't queue both a stop and a continue signal */
1145 if (sig == SIGCONT)
1146 sigdelsetmask(set: signal, SIG_KERNEL_STOP_MASK);
1147 else if (sig_kernel_stop(sig))
1148 sigdelset(set: signal, SIGCONT);
1149 sigaddset(set: signal, sig: sig);
1150 }
1151 }
1152
1153 complete_signal(sig, p: t, type);
1154ret:
1155 trace_signal_generate(sig, info, task: t, group: type != PIDTYPE_PID, result);
1156 return ret;
1157}
1158
1159static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1160{
1161 bool ret = false;
1162 switch (siginfo_layout(sig: info->si_signo, si_code: info->si_code)) {
1163 case SIL_KILL:
1164 case SIL_CHLD:
1165 case SIL_RT:
1166 ret = true;
1167 break;
1168 case SIL_TIMER:
1169 case SIL_POLL:
1170 case SIL_FAULT:
1171 case SIL_FAULT_TRAPNO:
1172 case SIL_FAULT_MCEERR:
1173 case SIL_FAULT_BNDERR:
1174 case SIL_FAULT_PKUERR:
1175 case SIL_FAULT_PERF_EVENT:
1176 case SIL_SYS:
1177 ret = false;
1178 break;
1179 }
1180 return ret;
1181}
1182
1183int send_signal_locked(int sig, struct kernel_siginfo *info,
1184 struct task_struct *t, enum pid_type type)
1185{
1186 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1187 bool force = false;
1188
1189 if (info == SEND_SIG_NOINFO) {
1190 /* Force if sent from an ancestor pid namespace */
1191 force = !task_pid_nr_ns(current, ns: task_active_pid_ns(tsk: t));
1192 } else if (info == SEND_SIG_PRIV) {
1193 /* Don't ignore kernel generated signals */
1194 force = true;
1195 } else if (has_si_pid_and_uid(info)) {
1196 /* SIGKILL and SIGSTOP is special or has ids */
1197 struct user_namespace *t_user_ns;
1198
1199 rcu_read_lock();
1200 t_user_ns = task_cred_xxx(t, user_ns);
1201 if (current_user_ns() != t_user_ns) {
1202 kuid_t uid = make_kuid(from: current_user_ns(), uid: info->si_uid);
1203 info->si_uid = from_kuid_munged(to: t_user_ns, kuid: uid);
1204 }
1205 rcu_read_unlock();
1206
1207 /* A kernel generated signal? */
1208 force = (info->si_code == SI_KERNEL);
1209
1210 /* From an ancestor pid namespace? */
1211 if (!task_pid_nr_ns(current, ns: task_active_pid_ns(tsk: t))) {
1212 info->si_pid = 0;
1213 force = true;
1214 }
1215 }
1216 return __send_signal_locked(sig, info, t, type, force);
1217}
1218
1219static void print_fatal_signal(int signr)
1220{
1221 struct pt_regs *regs = task_pt_regs(current);
1222 struct file *exe_file;
1223
1224 exe_file = get_task_exe_file(current);
1225 if (exe_file) {
1226 pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1227 exe_file, current->comm, signr);
1228 fput(exe_file);
1229 } else {
1230 pr_info("%s: potentially unexpected fatal signal %d.\n",
1231 current->comm, signr);
1232 }
1233
1234#if defined(__i386__) && !defined(__arch_um__)
1235 pr_info("code at %08lx: ", regs->ip);
1236 {
1237 int i;
1238 for (i = 0; i < 16; i++) {
1239 unsigned char insn;
1240
1241 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1242 break;
1243 pr_cont("%02x ", insn);
1244 }
1245 }
1246 pr_cont("\n");
1247#endif
1248 preempt_disable();
1249 show_regs(regs);
1250 preempt_enable();
1251}
1252
1253static int __init setup_print_fatal_signals(char *str)
1254{
1255 get_option (str: &str, pint: &print_fatal_signals);
1256
1257 return 1;
1258}
1259
1260__setup("print-fatal-signals=", setup_print_fatal_signals);
1261
1262int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1263 enum pid_type type)
1264{
1265 unsigned long flags;
1266 int ret = -ESRCH;
1267
1268 if (lock_task_sighand(task: p, flags: &flags)) {
1269 ret = send_signal_locked(sig, info, t: p, type);
1270 unlock_task_sighand(task: p, flags: &flags);
1271 }
1272
1273 return ret;
1274}
1275
1276enum sig_handler {
1277 HANDLER_CURRENT, /* If reachable use the current handler */
1278 HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1279 HANDLER_EXIT, /* Only visible as the process exit code */
1280};
1281
1282/*
1283 * Force a signal that the process can't ignore: if necessary
1284 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1285 *
1286 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1287 * since we do not want to have a signal handler that was blocked
1288 * be invoked when user space had explicitly blocked it.
1289 *
1290 * We don't want to have recursive SIGSEGV's etc, for example,
1291 * that is why we also clear SIGNAL_UNKILLABLE.
1292 */
1293static int
1294force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1295 enum sig_handler handler)
1296{
1297 unsigned long int flags;
1298 int ret, blocked, ignored;
1299 struct k_sigaction *action;
1300 int sig = info->si_signo;
1301
1302 spin_lock_irqsave(&t->sighand->siglock, flags);
1303 action = &t->sighand->action[sig-1];
1304 ignored = action->sa.sa_handler == SIG_IGN;
1305 blocked = sigismember(set: &t->blocked, sig: sig);
1306 if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1307 action->sa.sa_handler = SIG_DFL;
1308 if (handler == HANDLER_EXIT)
1309 action->sa.sa_flags |= SA_IMMUTABLE;
1310 if (blocked)
1311 sigdelset(set: &t->blocked, sig: sig);
1312 }
1313 /*
1314 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1315 * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1316 */
1317 if (action->sa.sa_handler == SIG_DFL &&
1318 (!t->ptrace || (handler == HANDLER_EXIT)))
1319 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1320 ret = send_signal_locked(sig, info, t, type: PIDTYPE_PID);
1321 /* This can happen if the signal was already pending and blocked */
1322 if (!task_sigpending(p: t))
1323 signal_wake_up(t, fatal: 0);
1324 spin_unlock_irqrestore(lock: &t->sighand->siglock, flags);
1325
1326 return ret;
1327}
1328
1329int force_sig_info(struct kernel_siginfo *info)
1330{
1331 return force_sig_info_to_task(info, current, handler: HANDLER_CURRENT);
1332}
1333
1334/*
1335 * Nuke all other threads in the group.
1336 */
1337int zap_other_threads(struct task_struct *p)
1338{
1339 struct task_struct *t;
1340 int count = 0;
1341
1342 p->signal->group_stop_count = 0;
1343
1344 for_other_threads(p, t) {
1345 task_clear_jobctl_pending(task: t, JOBCTL_PENDING_MASK);
1346 count++;
1347
1348 /* Don't bother with already dead threads */
1349 if (t->exit_state)
1350 continue;
1351 sigaddset(set: &t->pending.signal, SIGKILL);
1352 signal_wake_up(t, fatal: 1);
1353 }
1354
1355 return count;
1356}
1357
1358struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1359 unsigned long *flags)
1360{
1361 struct sighand_struct *sighand;
1362
1363 rcu_read_lock();
1364 for (;;) {
1365 sighand = rcu_dereference(tsk->sighand);
1366 if (unlikely(sighand == NULL))
1367 break;
1368
1369 /*
1370 * This sighand can be already freed and even reused, but
1371 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1372 * initializes ->siglock: this slab can't go away, it has
1373 * the same object type, ->siglock can't be reinitialized.
1374 *
1375 * We need to ensure that tsk->sighand is still the same
1376 * after we take the lock, we can race with de_thread() or
1377 * __exit_signal(). In the latter case the next iteration
1378 * must see ->sighand == NULL.
1379 */
1380 spin_lock_irqsave(&sighand->siglock, *flags);
1381 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1382 break;
1383 spin_unlock_irqrestore(lock: &sighand->siglock, flags: *flags);
1384 }
1385 rcu_read_unlock();
1386
1387 return sighand;
1388}
1389
1390#ifdef CONFIG_LOCKDEP
1391void lockdep_assert_task_sighand_held(struct task_struct *task)
1392{
1393 struct sighand_struct *sighand;
1394
1395 rcu_read_lock();
1396 sighand = rcu_dereference(task->sighand);
1397 if (sighand)
1398 lockdep_assert_held(&sighand->siglock);
1399 else
1400 WARN_ON_ONCE(1);
1401 rcu_read_unlock();
1402}
1403#endif
1404
1405/*
1406 * send signal info to all the members of a thread group or to the
1407 * individual thread if type == PIDTYPE_PID.
1408 */
1409int group_send_sig_info(int sig, struct kernel_siginfo *info,
1410 struct task_struct *p, enum pid_type type)
1411{
1412 int ret;
1413
1414 rcu_read_lock();
1415 ret = check_kill_permission(sig, info, t: p);
1416 rcu_read_unlock();
1417
1418 if (!ret && sig)
1419 ret = do_send_sig_info(sig, info, p, type);
1420
1421 return ret;
1422}
1423
1424/*
1425 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1426 * control characters do (^C, ^Z etc)
1427 * - the caller must hold at least a readlock on tasklist_lock
1428 */
1429int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1430{
1431 struct task_struct *p = NULL;
1432 int ret = -ESRCH;
1433
1434 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1435 int err = group_send_sig_info(sig, info, p, type: PIDTYPE_PGID);
1436 /*
1437 * If group_send_sig_info() succeeds at least once ret
1438 * becomes 0 and after that the code below has no effect.
1439 * Otherwise we return the last err or -ESRCH if this
1440 * process group is empty.
1441 */
1442 if (ret)
1443 ret = err;
1444 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1445
1446 return ret;
1447}
1448
1449static int kill_pid_info_type(int sig, struct kernel_siginfo *info,
1450 struct pid *pid, enum pid_type type)
1451{
1452 int error = -ESRCH;
1453 struct task_struct *p;
1454
1455 for (;;) {
1456 rcu_read_lock();
1457 p = pid_task(pid, PIDTYPE_PID);
1458 if (p)
1459 error = group_send_sig_info(sig, info, p, type);
1460 rcu_read_unlock();
1461 if (likely(!p || error != -ESRCH))
1462 return error;
1463 /*
1464 * The task was unhashed in between, try again. If it
1465 * is dead, pid_task() will return NULL, if we race with
1466 * de_thread() it will find the new leader.
1467 */
1468 }
1469}
1470
1471int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1472{
1473 return kill_pid_info_type(sig, info, pid, type: PIDTYPE_TGID);
1474}
1475
1476static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1477{
1478 int error;
1479 rcu_read_lock();
1480 error = kill_pid_info(sig, info, pid: find_vpid(nr: pid));
1481 rcu_read_unlock();
1482 return error;
1483}
1484
1485static inline bool kill_as_cred_perm(const struct cred *cred,
1486 struct task_struct *target)
1487{
1488 const struct cred *pcred = __task_cred(target);
1489
1490 return uid_eq(left: cred->euid, right: pcred->suid) ||
1491 uid_eq(left: cred->euid, right: pcred->uid) ||
1492 uid_eq(left: cred->uid, right: pcred->suid) ||
1493 uid_eq(left: cred->uid, right: pcred->uid);
1494}
1495
1496/*
1497 * The usb asyncio usage of siginfo is wrong. The glibc support
1498 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1499 * AKA after the generic fields:
1500 * kernel_pid_t si_pid;
1501 * kernel_uid32_t si_uid;
1502 * sigval_t si_value;
1503 *
1504 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1505 * after the generic fields is:
1506 * void __user *si_addr;
1507 *
1508 * This is a practical problem when there is a 64bit big endian kernel
1509 * and a 32bit userspace. As the 32bit address will encoded in the low
1510 * 32bits of the pointer. Those low 32bits will be stored at higher
1511 * address than appear in a 32 bit pointer. So userspace will not
1512 * see the address it was expecting for it's completions.
1513 *
1514 * There is nothing in the encoding that can allow
1515 * copy_siginfo_to_user32 to detect this confusion of formats, so
1516 * handle this by requiring the caller of kill_pid_usb_asyncio to
1517 * notice when this situration takes place and to store the 32bit
1518 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1519 * parameter.
1520 */
1521int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1522 struct pid *pid, const struct cred *cred)
1523{
1524 struct kernel_siginfo info;
1525 struct task_struct *p;
1526 unsigned long flags;
1527 int ret = -EINVAL;
1528
1529 if (!valid_signal(sig))
1530 return ret;
1531
1532 clear_siginfo(info: &info);
1533 info.si_signo = sig;
1534 info.si_errno = errno;
1535 info.si_code = SI_ASYNCIO;
1536 *((sigval_t *)&info.si_pid) = addr;
1537
1538 rcu_read_lock();
1539 p = pid_task(pid, PIDTYPE_PID);
1540 if (!p) {
1541 ret = -ESRCH;
1542 goto out_unlock;
1543 }
1544 if (!kill_as_cred_perm(cred, target: p)) {
1545 ret = -EPERM;
1546 goto out_unlock;
1547 }
1548 ret = security_task_kill(p, info: &info, sig, cred);
1549 if (ret)
1550 goto out_unlock;
1551
1552 if (sig) {
1553 if (lock_task_sighand(task: p, flags: &flags)) {
1554 ret = __send_signal_locked(sig, info: &info, t: p, type: PIDTYPE_TGID, force: false);
1555 unlock_task_sighand(task: p, flags: &flags);
1556 } else
1557 ret = -ESRCH;
1558 }
1559out_unlock:
1560 rcu_read_unlock();
1561 return ret;
1562}
1563EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1564
1565/*
1566 * kill_something_info() interprets pid in interesting ways just like kill(2).
1567 *
1568 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1569 * is probably wrong. Should make it like BSD or SYSV.
1570 */
1571
1572static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1573{
1574 int ret;
1575
1576 if (pid > 0)
1577 return kill_proc_info(sig, info, pid);
1578
1579 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1580 if (pid == INT_MIN)
1581 return -ESRCH;
1582
1583 read_lock(&tasklist_lock);
1584 if (pid != -1) {
1585 ret = __kill_pgrp_info(sig, info,
1586 pgrp: pid ? find_vpid(nr: -pid) : task_pgrp(current));
1587 } else {
1588 int retval = 0, count = 0;
1589 struct task_struct * p;
1590
1591 for_each_process(p) {
1592 if (task_pid_vnr(tsk: p) > 1 &&
1593 !same_thread_group(p1: p, current)) {
1594 int err = group_send_sig_info(sig, info, p,
1595 type: PIDTYPE_MAX);
1596 ++count;
1597 if (err != -EPERM)
1598 retval = err;
1599 }
1600 }
1601 ret = count ? retval : -ESRCH;
1602 }
1603 read_unlock(&tasklist_lock);
1604
1605 return ret;
1606}
1607
1608/*
1609 * These are for backward compatibility with the rest of the kernel source.
1610 */
1611
1612int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1613{
1614 /*
1615 * Make sure legacy kernel users don't send in bad values
1616 * (normal paths check this in check_kill_permission).
1617 */
1618 if (!valid_signal(sig))
1619 return -EINVAL;
1620
1621 return do_send_sig_info(sig, info, p, type: PIDTYPE_PID);
1622}
1623EXPORT_SYMBOL(send_sig_info);
1624
1625#define __si_special(priv) \
1626 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1627
1628int
1629send_sig(int sig, struct task_struct *p, int priv)
1630{
1631 return send_sig_info(sig, __si_special(priv), p);
1632}
1633EXPORT_SYMBOL(send_sig);
1634
1635void force_sig(int sig)
1636{
1637 struct kernel_siginfo info;
1638
1639 clear_siginfo(info: &info);
1640 info.si_signo = sig;
1641 info.si_errno = 0;
1642 info.si_code = SI_KERNEL;
1643 info.si_pid = 0;
1644 info.si_uid = 0;
1645 force_sig_info(info: &info);
1646}
1647EXPORT_SYMBOL(force_sig);
1648
1649void force_fatal_sig(int sig)
1650{
1651 struct kernel_siginfo info;
1652
1653 clear_siginfo(info: &info);
1654 info.si_signo = sig;
1655 info.si_errno = 0;
1656 info.si_code = SI_KERNEL;
1657 info.si_pid = 0;
1658 info.si_uid = 0;
1659 force_sig_info_to_task(info: &info, current, handler: HANDLER_SIG_DFL);
1660}
1661
1662void force_exit_sig(int sig)
1663{
1664 struct kernel_siginfo info;
1665
1666 clear_siginfo(info: &info);
1667 info.si_signo = sig;
1668 info.si_errno = 0;
1669 info.si_code = SI_KERNEL;
1670 info.si_pid = 0;
1671 info.si_uid = 0;
1672 force_sig_info_to_task(info: &info, current, handler: HANDLER_EXIT);
1673}
1674
1675/*
1676 * When things go south during signal handling, we
1677 * will force a SIGSEGV. And if the signal that caused
1678 * the problem was already a SIGSEGV, we'll want to
1679 * make sure we don't even try to deliver the signal..
1680 */
1681void force_sigsegv(int sig)
1682{
1683 if (sig == SIGSEGV)
1684 force_fatal_sig(SIGSEGV);
1685 else
1686 force_sig(SIGSEGV);
1687}
1688
1689int force_sig_fault_to_task(int sig, int code, void __user *addr,
1690 struct task_struct *t)
1691{
1692 struct kernel_siginfo info;
1693
1694 clear_siginfo(info: &info);
1695 info.si_signo = sig;
1696 info.si_errno = 0;
1697 info.si_code = code;
1698 info.si_addr = addr;
1699 return force_sig_info_to_task(info: &info, t, handler: HANDLER_CURRENT);
1700}
1701
1702int force_sig_fault(int sig, int code, void __user *addr)
1703{
1704 return force_sig_fault_to_task(sig, code, addr, current);
1705}
1706
1707int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t)
1708{
1709 struct kernel_siginfo info;
1710
1711 clear_siginfo(info: &info);
1712 info.si_signo = sig;
1713 info.si_errno = 0;
1714 info.si_code = code;
1715 info.si_addr = addr;
1716 return send_sig_info(info.si_signo, &info, t);
1717}
1718
1719int force_sig_mceerr(int code, void __user *addr, short lsb)
1720{
1721 struct kernel_siginfo info;
1722
1723 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1724 clear_siginfo(info: &info);
1725 info.si_signo = SIGBUS;
1726 info.si_errno = 0;
1727 info.si_code = code;
1728 info.si_addr = addr;
1729 info.si_addr_lsb = lsb;
1730 return force_sig_info(info: &info);
1731}
1732
1733int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1734{
1735 struct kernel_siginfo info;
1736
1737 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1738 clear_siginfo(info: &info);
1739 info.si_signo = SIGBUS;
1740 info.si_errno = 0;
1741 info.si_code = code;
1742 info.si_addr = addr;
1743 info.si_addr_lsb = lsb;
1744 return send_sig_info(info.si_signo, &info, t);
1745}
1746EXPORT_SYMBOL(send_sig_mceerr);
1747
1748int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1749{
1750 struct kernel_siginfo info;
1751
1752 clear_siginfo(info: &info);
1753 info.si_signo = SIGSEGV;
1754 info.si_errno = 0;
1755 info.si_code = SEGV_BNDERR;
1756 info.si_addr = addr;
1757 info.si_lower = lower;
1758 info.si_upper = upper;
1759 return force_sig_info(info: &info);
1760}
1761
1762#ifdef SEGV_PKUERR
1763int force_sig_pkuerr(void __user *addr, u32 pkey)
1764{
1765 struct kernel_siginfo info;
1766
1767 clear_siginfo(info: &info);
1768 info.si_signo = SIGSEGV;
1769 info.si_errno = 0;
1770 info.si_code = SEGV_PKUERR;
1771 info.si_addr = addr;
1772 info.si_pkey = pkey;
1773 return force_sig_info(info: &info);
1774}
1775#endif
1776
1777int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1778{
1779 struct kernel_siginfo info;
1780
1781 clear_siginfo(info: &info);
1782 info.si_signo = SIGTRAP;
1783 info.si_errno = 0;
1784 info.si_code = TRAP_PERF;
1785 info.si_addr = addr;
1786 info.si_perf_data = sig_data;
1787 info.si_perf_type = type;
1788
1789 /*
1790 * Signals generated by perf events should not terminate the whole
1791 * process if SIGTRAP is blocked, however, delivering the signal
1792 * asynchronously is better than not delivering at all. But tell user
1793 * space if the signal was asynchronous, so it can clearly be
1794 * distinguished from normal synchronous ones.
1795 */
1796 info.si_perf_flags = sigismember(set: &current->blocked, sig: info.si_signo) ?
1797 TRAP_PERF_FLAG_ASYNC :
1798 0;
1799
1800 return send_sig_info(info.si_signo, &info, current);
1801}
1802
1803/**
1804 * force_sig_seccomp - signals the task to allow in-process syscall emulation
1805 * @syscall: syscall number to send to userland
1806 * @reason: filter-supplied reason code to send to userland (via si_errno)
1807 * @force_coredump: true to trigger a coredump
1808 *
1809 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1810 */
1811int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1812{
1813 struct kernel_siginfo info;
1814
1815 clear_siginfo(info: &info);
1816 info.si_signo = SIGSYS;
1817 info.si_code = SYS_SECCOMP;
1818 info.si_call_addr = (void __user *)KSTK_EIP(current);
1819 info.si_errno = reason;
1820 info.si_arch = syscall_get_arch(current);
1821 info.si_syscall = syscall;
1822 return force_sig_info_to_task(info: &info, current,
1823 handler: force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1824}
1825
1826/* For the crazy architectures that include trap information in
1827 * the errno field, instead of an actual errno value.
1828 */
1829int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1830{
1831 struct kernel_siginfo info;
1832
1833 clear_siginfo(info: &info);
1834 info.si_signo = SIGTRAP;
1835 info.si_errno = errno;
1836 info.si_code = TRAP_HWBKPT;
1837 info.si_addr = addr;
1838 return force_sig_info(info: &info);
1839}
1840
1841/* For the rare architectures that include trap information using
1842 * si_trapno.
1843 */
1844int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1845{
1846 struct kernel_siginfo info;
1847
1848 clear_siginfo(info: &info);
1849 info.si_signo = sig;
1850 info.si_errno = 0;
1851 info.si_code = code;
1852 info.si_addr = addr;
1853 info.si_trapno = trapno;
1854 return force_sig_info(info: &info);
1855}
1856
1857/* For the rare architectures that include trap information using
1858 * si_trapno.
1859 */
1860int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1861 struct task_struct *t)
1862{
1863 struct kernel_siginfo info;
1864
1865 clear_siginfo(info: &info);
1866 info.si_signo = sig;
1867 info.si_errno = 0;
1868 info.si_code = code;
1869 info.si_addr = addr;
1870 info.si_trapno = trapno;
1871 return send_sig_info(info.si_signo, &info, t);
1872}
1873
1874static int kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1875{
1876 int ret;
1877 read_lock(&tasklist_lock);
1878 ret = __kill_pgrp_info(sig, info, pgrp);
1879 read_unlock(&tasklist_lock);
1880 return ret;
1881}
1882
1883int kill_pgrp(struct pid *pid, int sig, int priv)
1884{
1885 return kill_pgrp_info(sig, __si_special(priv), pgrp: pid);
1886}
1887EXPORT_SYMBOL(kill_pgrp);
1888
1889int kill_pid(struct pid *pid, int sig, int priv)
1890{
1891 return kill_pid_info(sig, __si_special(priv), pid);
1892}
1893EXPORT_SYMBOL(kill_pid);
1894
1895#ifdef CONFIG_POSIX_TIMERS
1896/*
1897 * These functions handle POSIX timer signals. POSIX timers use
1898 * preallocated sigqueue structs for sending signals.
1899 */
1900static void __flush_itimer_signals(struct sigpending *pending)
1901{
1902 sigset_t signal, retain;
1903 struct sigqueue *q, *n;
1904
1905 signal = pending->signal;
1906 sigemptyset(set: &retain);
1907
1908 list_for_each_entry_safe(q, n, &pending->list, list) {
1909 int sig = q->info.si_signo;
1910
1911 if (likely(q->info.si_code != SI_TIMER)) {
1912 sigaddset(set: &retain, sig: sig);
1913 } else {
1914 sigdelset(set: &signal, sig: sig);
1915 list_del_init(entry: &q->list);
1916 __sigqueue_free(q);
1917 }
1918 }
1919
1920 sigorsets(r: &pending->signal, a: &signal, b: &retain);
1921}
1922
1923void flush_itimer_signals(void)
1924{
1925 struct task_struct *tsk = current;
1926
1927 guard(spinlock_irqsave)(l: &tsk->sighand->siglock);
1928 __flush_itimer_signals(pending: &tsk->pending);
1929 __flush_itimer_signals(pending: &tsk->signal->shared_pending);
1930}
1931
1932bool posixtimer_init_sigqueue(struct sigqueue *q)
1933{
1934 struct ucounts *ucounts = sig_get_ucounts(current, sig: -1, override_rlimit: 0);
1935
1936 if (!ucounts)
1937 return false;
1938 clear_siginfo(info: &q->info);
1939 __sigqueue_init(q, ucounts, SIGQUEUE_PREALLOC);
1940 return true;
1941}
1942
1943static void posixtimer_queue_sigqueue(struct sigqueue *q, struct task_struct *t, enum pid_type type)
1944{
1945 struct sigpending *pending;
1946 int sig = q->info.si_signo;
1947
1948 signalfd_notify(tsk: t, sig);
1949 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1950 list_add_tail(new: &q->list, head: &pending->list);
1951 sigaddset(set: &pending->signal, sig: sig);
1952 complete_signal(sig, p: t, type);
1953}
1954
1955/*
1956 * This function is used by POSIX timers to deliver a timer signal.
1957 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1958 * set), the signal must be delivered to the specific thread (queues
1959 * into t->pending).
1960 *
1961 * Where type is not PIDTYPE_PID, signals must be delivered to the
1962 * process. In this case, prefer to deliver to current if it is in
1963 * the same thread group as the target process and its sighand is
1964 * stable, which avoids unnecessarily waking up a potentially idle task.
1965 */
1966static inline struct task_struct *posixtimer_get_target(struct k_itimer *tmr)
1967{
1968 struct task_struct *t = pid_task(pid: tmr->it_pid, tmr->it_pid_type);
1969
1970 if (t && tmr->it_pid_type != PIDTYPE_PID &&
1971 same_thread_group(p1: t, current) && !current->exit_state)
1972 t = current;
1973 return t;
1974}
1975
1976void posixtimer_send_sigqueue(struct k_itimer *tmr)
1977{
1978 struct sigqueue *q = &tmr->sigq;
1979 int sig = q->info.si_signo;
1980 struct task_struct *t;
1981 unsigned long flags;
1982 int result;
1983
1984 guard(rcu)();
1985
1986 t = posixtimer_get_target(tmr);
1987 if (!t)
1988 return;
1989
1990 if (!likely(lock_task_sighand(t, &flags)))
1991 return;
1992
1993 /*
1994 * Update @tmr::sigqueue_seq for posix timer signals with sighand
1995 * locked to prevent a race against dequeue_signal().
1996 */
1997 tmr->it_sigqueue_seq = tmr->it_signal_seq;
1998
1999 /*
2000 * Set the signal delivery status under sighand lock, so that the
2001 * ignored signal handling can distinguish between a periodic and a
2002 * non-periodic timer.
2003 */
2004 tmr->it_sig_periodic = tmr->it_status == POSIX_TIMER_REQUEUE_PENDING;
2005
2006 if (!prepare_signal(sig, p: t, force: false)) {
2007 result = TRACE_SIGNAL_IGNORED;
2008
2009 if (!list_empty(head: &q->list)) {
2010 /*
2011 * The signal was ignored and blocked. The timer
2012 * expiry queued it because blocked signals are
2013 * queued independent of the ignored state.
2014 *
2015 * The unblocking set SIGPENDING, but the signal
2016 * was not yet dequeued from the pending list.
2017 * So prepare_signal() sees unblocked and ignored,
2018 * which ends up here. Leave it queued like a
2019 * regular signal.
2020 *
2021 * The same happens when the task group is exiting
2022 * and the signal is already queued.
2023 * prepare_signal() treats SIGNAL_GROUP_EXIT as
2024 * ignored independent of its queued state. This
2025 * gets cleaned up in __exit_signal().
2026 */
2027 goto out;
2028 }
2029
2030 /* Periodic timers with SIG_IGN are queued on the ignored list */
2031 if (tmr->it_sig_periodic) {
2032 /*
2033 * Already queued means the timer was rearmed after
2034 * the previous expiry got it on the ignore list.
2035 * Nothing to do for that case.
2036 */
2037 if (hlist_unhashed(h: &tmr->ignored_list)) {
2038 /*
2039 * Take a signal reference and queue it on
2040 * the ignored list.
2041 */
2042 posixtimer_sigqueue_getref(q);
2043 posixtimer_sig_ignore(tsk: t, q);
2044 }
2045 } else if (!hlist_unhashed(h: &tmr->ignored_list)) {
2046 /*
2047 * Covers the case where a timer was periodic and
2048 * then the signal was ignored. Later it was rearmed
2049 * as oneshot timer. The previous signal is invalid
2050 * now, and this oneshot signal has to be dropped.
2051 * Remove it from the ignored list and drop the
2052 * reference count as the signal is not longer
2053 * queued.
2054 */
2055 hlist_del_init(n: &tmr->ignored_list);
2056 posixtimer_putref(tmr);
2057 }
2058 goto out;
2059 }
2060
2061 if (unlikely(!list_empty(&q->list))) {
2062 /* This holds a reference count already */
2063 result = TRACE_SIGNAL_ALREADY_PENDING;
2064 goto out;
2065 }
2066
2067 /*
2068 * If the signal is on the ignore list, it got blocked after it was
2069 * ignored earlier. But nothing lifted the ignore. Move it back to
2070 * the pending list to be consistent with the regular signal
2071 * handling. This already holds a reference count.
2072 *
2073 * If it's not on the ignore list acquire a reference count.
2074 */
2075 if (likely(hlist_unhashed(&tmr->ignored_list)))
2076 posixtimer_sigqueue_getref(q);
2077 else
2078 hlist_del_init(n: &tmr->ignored_list);
2079
2080 posixtimer_queue_sigqueue(q, t, type: tmr->it_pid_type);
2081 result = TRACE_SIGNAL_DELIVERED;
2082out:
2083 trace_signal_generate(sig, info: &q->info, task: t, group: tmr->it_pid_type != PIDTYPE_PID, result);
2084 unlock_task_sighand(task: t, flags: &flags);
2085}
2086
2087static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q)
2088{
2089 struct k_itimer *tmr = container_of(q, struct k_itimer, sigq);
2090
2091 /*
2092 * If the timer is marked deleted already or the signal originates
2093 * from a non-periodic timer, then just drop the reference
2094 * count. Otherwise queue it on the ignored list.
2095 */
2096 if (posixtimer_valid(timer: tmr) && tmr->it_sig_periodic)
2097 hlist_add_head(n: &tmr->ignored_list, h: &tsk->signal->ignored_posix_timers);
2098 else
2099 posixtimer_putref(tmr);
2100}
2101
2102static void posixtimer_sig_unignore(struct task_struct *tsk, int sig)
2103{
2104 struct hlist_head *head = &tsk->signal->ignored_posix_timers;
2105 struct hlist_node *tmp;
2106 struct k_itimer *tmr;
2107
2108 if (likely(hlist_empty(head)))
2109 return;
2110
2111 /*
2112 * Rearming a timer with sighand lock held is not possible due to
2113 * lock ordering vs. tmr::it_lock. Just stick the sigqueue back and
2114 * let the signal delivery path deal with it whether it needs to be
2115 * rearmed or not. This cannot be decided here w/o dropping sighand
2116 * lock and creating a loop retry horror show.
2117 */
2118 hlist_for_each_entry_safe(tmr, tmp , head, ignored_list) {
2119 struct task_struct *target;
2120
2121 /*
2122 * tmr::sigq.info.si_signo is immutable, so accessing it
2123 * without holding tmr::it_lock is safe.
2124 */
2125 if (tmr->sigq.info.si_signo != sig)
2126 continue;
2127
2128 hlist_del_init(n: &tmr->ignored_list);
2129
2130 /* This should never happen and leaks a reference count */
2131 if (WARN_ON_ONCE(!list_empty(&tmr->sigq.list)))
2132 continue;
2133
2134 /*
2135 * Get the target for the signal. If target is a thread and
2136 * has exited by now, drop the reference count.
2137 */
2138 guard(rcu)();
2139 target = posixtimer_get_target(tmr);
2140 if (target)
2141 posixtimer_queue_sigqueue(q: &tmr->sigq, t: target, type: tmr->it_pid_type);
2142 else
2143 posixtimer_putref(tmr);
2144 }
2145}
2146#else /* CONFIG_POSIX_TIMERS */
2147static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q) { }
2148static inline void posixtimer_sig_unignore(struct task_struct *tsk, int sig) { }
2149#endif /* !CONFIG_POSIX_TIMERS */
2150
2151void do_notify_pidfd(struct task_struct *task)
2152{
2153 struct pid *pid = task_pid(task);
2154
2155 WARN_ON(task->exit_state == 0);
2156
2157 __wake_up(wq_head: &pid->wait_pidfd, TASK_NORMAL, nr: 0,
2158 poll_to_key(EPOLLIN | EPOLLRDNORM));
2159}
2160
2161/*
2162 * Let a parent know about the death of a child.
2163 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2164 *
2165 * Returns true if our parent ignored us and so we've switched to
2166 * self-reaping.
2167 */
2168bool do_notify_parent(struct task_struct *tsk, int sig)
2169{
2170 struct kernel_siginfo info;
2171 unsigned long flags;
2172 struct sighand_struct *psig;
2173 bool autoreap = false;
2174 u64 utime, stime;
2175
2176 WARN_ON_ONCE(sig == -1);
2177
2178 /* do_notify_parent_cldstop should have been called instead. */
2179 WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2180
2181 WARN_ON_ONCE(!tsk->ptrace &&
2182 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2183
2184 /* ptraced, or group-leader without sub-threads */
2185 do_notify_pidfd(task: tsk);
2186
2187 if (sig != SIGCHLD) {
2188 /*
2189 * This is only possible if parent == real_parent.
2190 * Check if it has changed security domain.
2191 */
2192 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2193 sig = SIGCHLD;
2194 }
2195
2196 clear_siginfo(info: &info);
2197 info.si_signo = sig;
2198 info.si_errno = 0;
2199 /*
2200 * We are under tasklist_lock here so our parent is tied to
2201 * us and cannot change.
2202 *
2203 * task_active_pid_ns will always return the same pid namespace
2204 * until a task passes through release_task.
2205 *
2206 * write_lock() currently calls preempt_disable() which is the
2207 * same as rcu_read_lock(), but according to Oleg, this is not
2208 * correct to rely on this
2209 */
2210 rcu_read_lock();
2211 info.si_pid = task_pid_nr_ns(tsk, ns: task_active_pid_ns(tsk: tsk->parent));
2212 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2213 task_uid(tsk));
2214 rcu_read_unlock();
2215
2216 task_cputime(t: tsk, utime: &utime, stime: &stime);
2217 info.si_utime = nsec_to_clock_t(x: utime + tsk->signal->utime);
2218 info.si_stime = nsec_to_clock_t(x: stime + tsk->signal->stime);
2219
2220 info.si_status = tsk->exit_code & 0x7f;
2221 if (tsk->exit_code & 0x80)
2222 info.si_code = CLD_DUMPED;
2223 else if (tsk->exit_code & 0x7f)
2224 info.si_code = CLD_KILLED;
2225 else {
2226 info.si_code = CLD_EXITED;
2227 info.si_status = tsk->exit_code >> 8;
2228 }
2229
2230 psig = tsk->parent->sighand;
2231 spin_lock_irqsave(&psig->siglock, flags);
2232 if (!tsk->ptrace && sig == SIGCHLD &&
2233 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2234 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2235 /*
2236 * We are exiting and our parent doesn't care. POSIX.1
2237 * defines special semantics for setting SIGCHLD to SIG_IGN
2238 * or setting the SA_NOCLDWAIT flag: we should be reaped
2239 * automatically and not left for our parent's wait4 call.
2240 * Rather than having the parent do it as a magic kind of
2241 * signal handler, we just set this to tell do_exit that we
2242 * can be cleaned up without becoming a zombie. Note that
2243 * we still call __wake_up_parent in this case, because a
2244 * blocked sys_wait4 might now return -ECHILD.
2245 *
2246 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2247 * is implementation-defined: we do (if you don't want
2248 * it, just use SIG_IGN instead).
2249 */
2250 autoreap = true;
2251 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2252 sig = 0;
2253 }
2254 /*
2255 * Send with __send_signal as si_pid and si_uid are in the
2256 * parent's namespaces.
2257 */
2258 if (valid_signal(sig) && sig)
2259 __send_signal_locked(sig, info: &info, t: tsk->parent, type: PIDTYPE_TGID, force: false);
2260 __wake_up_parent(p: tsk, parent: tsk->parent);
2261 spin_unlock_irqrestore(lock: &psig->siglock, flags);
2262
2263 return autoreap;
2264}
2265
2266/**
2267 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2268 * @tsk: task reporting the state change
2269 * @for_ptracer: the notification is for ptracer
2270 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2271 *
2272 * Notify @tsk's parent that the stopped/continued state has changed. If
2273 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2274 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2275 *
2276 * CONTEXT:
2277 * Must be called with tasklist_lock at least read locked.
2278 */
2279static void do_notify_parent_cldstop(struct task_struct *tsk,
2280 bool for_ptracer, int why)
2281{
2282 struct kernel_siginfo info;
2283 unsigned long flags;
2284 struct task_struct *parent;
2285 struct sighand_struct *sighand;
2286 u64 utime, stime;
2287
2288 if (for_ptracer) {
2289 parent = tsk->parent;
2290 } else {
2291 tsk = tsk->group_leader;
2292 parent = tsk->real_parent;
2293 }
2294
2295 clear_siginfo(info: &info);
2296 info.si_signo = SIGCHLD;
2297 info.si_errno = 0;
2298 /*
2299 * see comment in do_notify_parent() about the following 4 lines
2300 */
2301 rcu_read_lock();
2302 info.si_pid = task_pid_nr_ns(tsk, ns: task_active_pid_ns(tsk: parent));
2303 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2304 rcu_read_unlock();
2305
2306 task_cputime(t: tsk, utime: &utime, stime: &stime);
2307 info.si_utime = nsec_to_clock_t(x: utime);
2308 info.si_stime = nsec_to_clock_t(x: stime);
2309
2310 info.si_code = why;
2311 switch (why) {
2312 case CLD_CONTINUED:
2313 info.si_status = SIGCONT;
2314 break;
2315 case CLD_STOPPED:
2316 info.si_status = tsk->signal->group_exit_code & 0x7f;
2317 break;
2318 case CLD_TRAPPED:
2319 info.si_status = tsk->exit_code & 0x7f;
2320 break;
2321 default:
2322 BUG();
2323 }
2324
2325 sighand = parent->sighand;
2326 spin_lock_irqsave(&sighand->siglock, flags);
2327 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2328 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2329 send_signal_locked(SIGCHLD, info: &info, t: parent, type: PIDTYPE_TGID);
2330 /*
2331 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2332 */
2333 __wake_up_parent(p: tsk, parent);
2334 spin_unlock_irqrestore(lock: &sighand->siglock, flags);
2335}
2336
2337/*
2338 * This must be called with current->sighand->siglock held.
2339 *
2340 * This should be the path for all ptrace stops.
2341 * We always set current->last_siginfo while stopped here.
2342 * That makes it a way to test a stopped process for
2343 * being ptrace-stopped vs being job-control-stopped.
2344 *
2345 * Returns the signal the ptracer requested the code resume
2346 * with. If the code did not stop because the tracer is gone,
2347 * the stop signal remains unchanged unless clear_code.
2348 */
2349static int ptrace_stop(int exit_code, int why, unsigned long message,
2350 kernel_siginfo_t *info)
2351 __releases(&current->sighand->siglock)
2352 __acquires(&current->sighand->siglock)
2353{
2354 bool gstop_done = false;
2355
2356 if (arch_ptrace_stop_needed()) {
2357 /*
2358 * The arch code has something special to do before a
2359 * ptrace stop. This is allowed to block, e.g. for faults
2360 * on user stack pages. We can't keep the siglock while
2361 * calling arch_ptrace_stop, so we must release it now.
2362 * To preserve proper semantics, we must do this before
2363 * any signal bookkeeping like checking group_stop_count.
2364 */
2365 spin_unlock_irq(lock: &current->sighand->siglock);
2366 arch_ptrace_stop();
2367 spin_lock_irq(lock: &current->sighand->siglock);
2368 }
2369
2370 /*
2371 * After this point ptrace_signal_wake_up or signal_wake_up
2372 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
2373 * signal comes in. Handle previous ptrace_unlinks and fatal
2374 * signals here to prevent ptrace_stop sleeping in schedule.
2375 */
2376 if (!current->ptrace || __fatal_signal_pending(current))
2377 return exit_code;
2378
2379 set_special_state(TASK_TRACED);
2380 current->jobctl |= JOBCTL_TRACED;
2381
2382 /*
2383 * We're committing to trapping. TRACED should be visible before
2384 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2385 * Also, transition to TRACED and updates to ->jobctl should be
2386 * atomic with respect to siglock and should be done after the arch
2387 * hook as siglock is released and regrabbed across it.
2388 *
2389 * TRACER TRACEE
2390 *
2391 * ptrace_attach()
2392 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2393 * do_wait()
2394 * set_current_state() smp_wmb();
2395 * ptrace_do_wait()
2396 * wait_task_stopped()
2397 * task_stopped_code()
2398 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2399 */
2400 smp_wmb();
2401
2402 current->ptrace_message = message;
2403 current->last_siginfo = info;
2404 current->exit_code = exit_code;
2405
2406 /*
2407 * If @why is CLD_STOPPED, we're trapping to participate in a group
2408 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2409 * across siglock relocks since INTERRUPT was scheduled, PENDING
2410 * could be clear now. We act as if SIGCONT is received after
2411 * TASK_TRACED is entered - ignore it.
2412 */
2413 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2414 gstop_done = task_participate_group_stop(current);
2415
2416 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2417 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2418 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2419 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2420
2421 /* entering a trap, clear TRAPPING */
2422 task_clear_jobctl_trapping(current);
2423
2424 spin_unlock_irq(lock: &current->sighand->siglock);
2425 read_lock(&tasklist_lock);
2426 /*
2427 * Notify parents of the stop.
2428 *
2429 * While ptraced, there are two parents - the ptracer and
2430 * the real_parent of the group_leader. The ptracer should
2431 * know about every stop while the real parent is only
2432 * interested in the completion of group stop. The states
2433 * for the two don't interact with each other. Notify
2434 * separately unless they're gonna be duplicates.
2435 */
2436 if (current->ptrace)
2437 do_notify_parent_cldstop(current, for_ptracer: true, why);
2438 if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2439 do_notify_parent_cldstop(current, for_ptracer: false, why);
2440
2441 /*
2442 * The previous do_notify_parent_cldstop() invocation woke ptracer.
2443 * One a PREEMPTION kernel this can result in preemption requirement
2444 * which will be fulfilled after read_unlock() and the ptracer will be
2445 * put on the CPU.
2446 * The ptracer is in wait_task_inactive(, __TASK_TRACED) waiting for
2447 * this task wait in schedule(). If this task gets preempted then it
2448 * remains enqueued on the runqueue. The ptracer will observe this and
2449 * then sleep for a delay of one HZ tick. In the meantime this task
2450 * gets scheduled, enters schedule() and will wait for the ptracer.
2451 *
2452 * This preemption point is not bad from a correctness point of
2453 * view but extends the runtime by one HZ tick time due to the
2454 * ptracer's sleep. The preempt-disable section ensures that there
2455 * will be no preemption between unlock and schedule() and so
2456 * improving the performance since the ptracer will observe that
2457 * the tracee is scheduled out once it gets on the CPU.
2458 *
2459 * On PREEMPT_RT locking tasklist_lock does not disable preemption.
2460 * Therefore the task can be preempted after do_notify_parent_cldstop()
2461 * before unlocking tasklist_lock so there is no benefit in doing this.
2462 *
2463 * In fact disabling preemption is harmful on PREEMPT_RT because
2464 * the spinlock_t in cgroup_enter_frozen() must not be acquired
2465 * with preemption disabled due to the 'sleeping' spinlock
2466 * substitution of RT.
2467 */
2468 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2469 preempt_disable();
2470 read_unlock(&tasklist_lock);
2471 cgroup_enter_frozen();
2472 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2473 preempt_enable_no_resched();
2474 schedule();
2475 cgroup_leave_frozen(always_leave: true);
2476
2477 /*
2478 * We are back. Now reacquire the siglock before touching
2479 * last_siginfo, so that we are sure to have synchronized with
2480 * any signal-sending on another CPU that wants to examine it.
2481 */
2482 spin_lock_irq(lock: &current->sighand->siglock);
2483 exit_code = current->exit_code;
2484 current->last_siginfo = NULL;
2485 current->ptrace_message = 0;
2486 current->exit_code = 0;
2487
2488 /* LISTENING can be set only during STOP traps, clear it */
2489 current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2490
2491 /*
2492 * Queued signals ignored us while we were stopped for tracing.
2493 * So check for any that we should take before resuming user mode.
2494 * This sets TIF_SIGPENDING, but never clears it.
2495 */
2496 recalc_sigpending_tsk(current);
2497 return exit_code;
2498}
2499
2500static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2501{
2502 kernel_siginfo_t info;
2503
2504 clear_siginfo(info: &info);
2505 info.si_signo = signr;
2506 info.si_code = exit_code;
2507 info.si_pid = task_pid_vnr(current);
2508 info.si_uid = from_kuid_munged(to: current_user_ns(), current_uid());
2509
2510 /* Let the debugger run. */
2511 return ptrace_stop(exit_code, why, message, info: &info);
2512}
2513
2514int ptrace_notify(int exit_code, unsigned long message)
2515{
2516 int signr;
2517
2518 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2519 if (unlikely(task_work_pending(current)))
2520 task_work_run();
2521
2522 spin_lock_irq(lock: &current->sighand->siglock);
2523 signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2524 spin_unlock_irq(lock: &current->sighand->siglock);
2525 return signr;
2526}
2527
2528/**
2529 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2530 * @signr: signr causing group stop if initiating
2531 *
2532 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2533 * and participate in it. If already set, participate in the existing
2534 * group stop. If participated in a group stop (and thus slept), %true is
2535 * returned with siglock released.
2536 *
2537 * If ptraced, this function doesn't handle stop itself. Instead,
2538 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2539 * untouched. The caller must ensure that INTERRUPT trap handling takes
2540 * places afterwards.
2541 *
2542 * CONTEXT:
2543 * Must be called with @current->sighand->siglock held, which is released
2544 * on %true return.
2545 *
2546 * RETURNS:
2547 * %false if group stop is already cancelled or ptrace trap is scheduled.
2548 * %true if participated in group stop.
2549 */
2550static bool do_signal_stop(int signr)
2551 __releases(&current->sighand->siglock)
2552{
2553 struct signal_struct *sig = current->signal;
2554
2555 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2556 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2557 struct task_struct *t;
2558
2559 /* signr will be recorded in task->jobctl for retries */
2560 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2561
2562 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2563 unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2564 unlikely(sig->group_exec_task))
2565 return false;
2566 /*
2567 * There is no group stop already in progress. We must
2568 * initiate one now.
2569 *
2570 * While ptraced, a task may be resumed while group stop is
2571 * still in effect and then receive a stop signal and
2572 * initiate another group stop. This deviates from the
2573 * usual behavior as two consecutive stop signals can't
2574 * cause two group stops when !ptraced. That is why we
2575 * also check !task_is_stopped(t) below.
2576 *
2577 * The condition can be distinguished by testing whether
2578 * SIGNAL_STOP_STOPPED is already set. Don't generate
2579 * group_exit_code in such case.
2580 *
2581 * This is not necessary for SIGNAL_STOP_CONTINUED because
2582 * an intervening stop signal is required to cause two
2583 * continued events regardless of ptrace.
2584 */
2585 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2586 sig->group_exit_code = signr;
2587
2588 sig->group_stop_count = 0;
2589 if (task_set_jobctl_pending(current, mask: signr | gstop))
2590 sig->group_stop_count++;
2591
2592 for_other_threads(current, t) {
2593 /*
2594 * Setting state to TASK_STOPPED for a group
2595 * stop is always done with the siglock held,
2596 * so this check has no races.
2597 */
2598 if (!task_is_stopped(t) &&
2599 task_set_jobctl_pending(task: t, mask: signr | gstop)) {
2600 sig->group_stop_count++;
2601 if (likely(!(t->ptrace & PT_SEIZED)))
2602 signal_wake_up(t, fatal: 0);
2603 else
2604 ptrace_trap_notify(t);
2605 }
2606 }
2607 }
2608
2609 if (likely(!current->ptrace)) {
2610 int notify = 0;
2611
2612 /*
2613 * If there are no other threads in the group, or if there
2614 * is a group stop in progress and we are the last to stop,
2615 * report to the parent.
2616 */
2617 if (task_participate_group_stop(current))
2618 notify = CLD_STOPPED;
2619
2620 current->jobctl |= JOBCTL_STOPPED;
2621 set_special_state(TASK_STOPPED);
2622 spin_unlock_irq(lock: &current->sighand->siglock);
2623
2624 /*
2625 * Notify the parent of the group stop completion. Because
2626 * we're not holding either the siglock or tasklist_lock
2627 * here, ptracer may attach inbetween; however, this is for
2628 * group stop and should always be delivered to the real
2629 * parent of the group leader. The new ptracer will get
2630 * its notification when this task transitions into
2631 * TASK_TRACED.
2632 */
2633 if (notify) {
2634 read_lock(&tasklist_lock);
2635 do_notify_parent_cldstop(current, for_ptracer: false, why: notify);
2636 read_unlock(&tasklist_lock);
2637 }
2638
2639 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2640 cgroup_enter_frozen();
2641 schedule();
2642 return true;
2643 } else {
2644 /*
2645 * While ptraced, group stop is handled by STOP trap.
2646 * Schedule it and let the caller deal with it.
2647 */
2648 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2649 return false;
2650 }
2651}
2652
2653/**
2654 * do_jobctl_trap - take care of ptrace jobctl traps
2655 *
2656 * When PT_SEIZED, it's used for both group stop and explicit
2657 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2658 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2659 * the stop signal; otherwise, %SIGTRAP.
2660 *
2661 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2662 * number as exit_code and no siginfo.
2663 *
2664 * CONTEXT:
2665 * Must be called with @current->sighand->siglock held, which may be
2666 * released and re-acquired before returning with intervening sleep.
2667 */
2668static void do_jobctl_trap(void)
2669{
2670 struct signal_struct *signal = current->signal;
2671 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2672
2673 if (current->ptrace & PT_SEIZED) {
2674 if (!signal->group_stop_count &&
2675 !(signal->flags & SIGNAL_STOP_STOPPED))
2676 signr = SIGTRAP;
2677 WARN_ON_ONCE(!signr);
2678 ptrace_do_notify(signr, exit_code: signr | (PTRACE_EVENT_STOP << 8),
2679 CLD_STOPPED, message: 0);
2680 } else {
2681 WARN_ON_ONCE(!signr);
2682 ptrace_stop(exit_code: signr, CLD_STOPPED, message: 0, NULL);
2683 }
2684}
2685
2686/**
2687 * do_freezer_trap - handle the freezer jobctl trap
2688 *
2689 * Puts the task into frozen state, if only the task is not about to quit.
2690 * In this case it drops JOBCTL_TRAP_FREEZE.
2691 *
2692 * CONTEXT:
2693 * Must be called with @current->sighand->siglock held,
2694 * which is always released before returning.
2695 */
2696static void do_freezer_trap(void)
2697 __releases(&current->sighand->siglock)
2698{
2699 /*
2700 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2701 * let's make another loop to give it a chance to be handled.
2702 * In any case, we'll return back.
2703 */
2704 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2705 JOBCTL_TRAP_FREEZE) {
2706 spin_unlock_irq(lock: &current->sighand->siglock);
2707 return;
2708 }
2709
2710 /*
2711 * Now we're sure that there is no pending fatal signal and no
2712 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2713 * immediately (if there is a non-fatal signal pending), and
2714 * put the task into sleep.
2715 */
2716 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2717 clear_thread_flag(TIF_SIGPENDING);
2718 spin_unlock_irq(lock: &current->sighand->siglock);
2719 cgroup_enter_frozen();
2720 schedule();
2721
2722 /*
2723 * We could've been woken by task_work, run it to clear
2724 * TIF_NOTIFY_SIGNAL. The caller will retry if necessary.
2725 */
2726 clear_notify_signal();
2727 if (unlikely(task_work_pending(current)))
2728 task_work_run();
2729}
2730
2731static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2732{
2733 /*
2734 * We do not check sig_kernel_stop(signr) but set this marker
2735 * unconditionally because we do not know whether debugger will
2736 * change signr. This flag has no meaning unless we are going
2737 * to stop after return from ptrace_stop(). In this case it will
2738 * be checked in do_signal_stop(), we should only stop if it was
2739 * not cleared by SIGCONT while we were sleeping. See also the
2740 * comment in dequeue_signal().
2741 */
2742 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2743 signr = ptrace_stop(exit_code: signr, CLD_TRAPPED, message: 0, info);
2744
2745 /* We're back. Did the debugger cancel the sig? */
2746 if (signr == 0)
2747 return signr;
2748
2749 /*
2750 * Update the siginfo structure if the signal has
2751 * changed. If the debugger wanted something
2752 * specific in the siginfo structure then it should
2753 * have updated *info via PTRACE_SETSIGINFO.
2754 */
2755 if (signr != info->si_signo) {
2756 clear_siginfo(info);
2757 info->si_signo = signr;
2758 info->si_errno = 0;
2759 info->si_code = SI_USER;
2760 rcu_read_lock();
2761 info->si_pid = task_pid_vnr(current->parent);
2762 info->si_uid = from_kuid_munged(to: current_user_ns(),
2763 task_uid(current->parent));
2764 rcu_read_unlock();
2765 }
2766
2767 /* If the (new) signal is now blocked, requeue it. */
2768 if (sigismember(set: &current->blocked, sig: signr) ||
2769 fatal_signal_pending(current)) {
2770 send_signal_locked(sig: signr, info, current, type);
2771 signr = 0;
2772 }
2773
2774 return signr;
2775}
2776
2777static void hide_si_addr_tag_bits(struct ksignal *ksig)
2778{
2779 switch (siginfo_layout(sig: ksig->sig, si_code: ksig->info.si_code)) {
2780 case SIL_FAULT:
2781 case SIL_FAULT_TRAPNO:
2782 case SIL_FAULT_MCEERR:
2783 case SIL_FAULT_BNDERR:
2784 case SIL_FAULT_PKUERR:
2785 case SIL_FAULT_PERF_EVENT:
2786 ksig->info.si_addr = arch_untagged_si_addr(
2787 addr: ksig->info.si_addr, sig: ksig->sig, si_code: ksig->info.si_code);
2788 break;
2789 case SIL_KILL:
2790 case SIL_TIMER:
2791 case SIL_POLL:
2792 case SIL_CHLD:
2793 case SIL_RT:
2794 case SIL_SYS:
2795 break;
2796 }
2797}
2798
2799bool get_signal(struct ksignal *ksig)
2800{
2801 struct sighand_struct *sighand = current->sighand;
2802 struct signal_struct *signal = current->signal;
2803 int signr;
2804
2805 clear_notify_signal();
2806 if (unlikely(task_work_pending(current)))
2807 task_work_run();
2808
2809 if (!task_sigpending(current))
2810 return false;
2811
2812 if (unlikely(uprobe_deny_signal()))
2813 return false;
2814
2815 /*
2816 * Do this once, we can't return to user-mode if freezing() == T.
2817 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2818 * thus do not need another check after return.
2819 */
2820 try_to_freeze();
2821
2822relock:
2823 spin_lock_irq(lock: &sighand->siglock);
2824
2825 /*
2826 * Every stopped thread goes here after wakeup. Check to see if
2827 * we should notify the parent, prepare_signal(SIGCONT) encodes
2828 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2829 */
2830 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2831 int why;
2832
2833 if (signal->flags & SIGNAL_CLD_CONTINUED)
2834 why = CLD_CONTINUED;
2835 else
2836 why = CLD_STOPPED;
2837
2838 signal->flags &= ~SIGNAL_CLD_MASK;
2839
2840 spin_unlock_irq(lock: &sighand->siglock);
2841
2842 /*
2843 * Notify the parent that we're continuing. This event is
2844 * always per-process and doesn't make whole lot of sense
2845 * for ptracers, who shouldn't consume the state via
2846 * wait(2) either, but, for backward compatibility, notify
2847 * the ptracer of the group leader too unless it's gonna be
2848 * a duplicate.
2849 */
2850 read_lock(&tasklist_lock);
2851 do_notify_parent_cldstop(current, for_ptracer: false, why);
2852
2853 if (ptrace_reparented(current->group_leader))
2854 do_notify_parent_cldstop(current->group_leader,
2855 for_ptracer: true, why);
2856 read_unlock(&tasklist_lock);
2857
2858 goto relock;
2859 }
2860
2861 for (;;) {
2862 struct k_sigaction *ka;
2863 enum pid_type type;
2864
2865 /* Has this task already been marked for death? */
2866 if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2867 signal->group_exec_task) {
2868 signr = SIGKILL;
2869 sigdelset(set: &current->pending.signal, SIGKILL);
2870 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2871 ka: &sighand->action[SIGKILL-1]);
2872 recalc_sigpending();
2873 /*
2874 * implies do_group_exit() or return to PF_USER_WORKER,
2875 * no need to initialize ksig->info/etc.
2876 */
2877 goto fatal;
2878 }
2879
2880 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2881 do_signal_stop(signr: 0))
2882 goto relock;
2883
2884 if (unlikely(current->jobctl &
2885 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2886 if (current->jobctl & JOBCTL_TRAP_MASK) {
2887 do_jobctl_trap();
2888 spin_unlock_irq(lock: &sighand->siglock);
2889 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2890 do_freezer_trap();
2891
2892 goto relock;
2893 }
2894
2895 /*
2896 * If the task is leaving the frozen state, let's update
2897 * cgroup counters and reset the frozen bit.
2898 */
2899 if (unlikely(cgroup_task_frozen(current))) {
2900 spin_unlock_irq(lock: &sighand->siglock);
2901 cgroup_leave_frozen(always_leave: false);
2902 goto relock;
2903 }
2904
2905 /*
2906 * Signals generated by the execution of an instruction
2907 * need to be delivered before any other pending signals
2908 * so that the instruction pointer in the signal stack
2909 * frame points to the faulting instruction.
2910 */
2911 type = PIDTYPE_PID;
2912 signr = dequeue_synchronous_signal(info: &ksig->info);
2913 if (!signr)
2914 signr = dequeue_signal(&current->blocked, &ksig->info, &type);
2915
2916 if (!signr)
2917 break; /* will return 0 */
2918
2919 if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2920 !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2921 signr = ptrace_signal(signr, info: &ksig->info, type);
2922 if (!signr)
2923 continue;
2924 }
2925
2926 ka = &sighand->action[signr-1];
2927
2928 /* Trace actually delivered signals. */
2929 trace_signal_deliver(sig: signr, info: &ksig->info, ka);
2930
2931 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2932 continue;
2933 if (ka->sa.sa_handler != SIG_DFL) {
2934 /* Run the handler. */
2935 ksig->ka = *ka;
2936
2937 if (ka->sa.sa_flags & SA_ONESHOT)
2938 ka->sa.sa_handler = SIG_DFL;
2939
2940 break; /* will return non-zero "signr" value */
2941 }
2942
2943 /*
2944 * Now we are doing the default action for this signal.
2945 */
2946 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2947 continue;
2948
2949 /*
2950 * Global init gets no signals it doesn't want.
2951 * Container-init gets no signals it doesn't want from same
2952 * container.
2953 *
2954 * Note that if global/container-init sees a sig_kernel_only()
2955 * signal here, the signal must have been generated internally
2956 * or must have come from an ancestor namespace. In either
2957 * case, the signal cannot be dropped.
2958 */
2959 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2960 !sig_kernel_only(signr))
2961 continue;
2962
2963 if (sig_kernel_stop(signr)) {
2964 /*
2965 * The default action is to stop all threads in
2966 * the thread group. The job control signals
2967 * do nothing in an orphaned pgrp, but SIGSTOP
2968 * always works. Note that siglock needs to be
2969 * dropped during the call to is_orphaned_pgrp()
2970 * because of lock ordering with tasklist_lock.
2971 * This allows an intervening SIGCONT to be posted.
2972 * We need to check for that and bail out if necessary.
2973 */
2974 if (signr != SIGSTOP) {
2975 spin_unlock_irq(lock: &sighand->siglock);
2976
2977 /* signals can be posted during this window */
2978
2979 if (is_current_pgrp_orphaned())
2980 goto relock;
2981
2982 spin_lock_irq(lock: &sighand->siglock);
2983 }
2984
2985 if (likely(do_signal_stop(signr))) {
2986 /* It released the siglock. */
2987 goto relock;
2988 }
2989
2990 /*
2991 * We didn't actually stop, due to a race
2992 * with SIGCONT or something like that.
2993 */
2994 continue;
2995 }
2996
2997 fatal:
2998 spin_unlock_irq(lock: &sighand->siglock);
2999 if (unlikely(cgroup_task_frozen(current)))
3000 cgroup_leave_frozen(always_leave: true);
3001
3002 /*
3003 * Anything else is fatal, maybe with a core dump.
3004 */
3005 current->flags |= PF_SIGNALED;
3006
3007 if (sig_kernel_coredump(signr)) {
3008 if (print_fatal_signals)
3009 print_fatal_signal(signr);
3010 proc_coredump_connector(current);
3011 /*
3012 * If it was able to dump core, this kills all
3013 * other threads in the group and synchronizes with
3014 * their demise. If we lost the race with another
3015 * thread getting here, it set group_exit_code
3016 * first and our do_group_exit call below will use
3017 * that value and ignore the one we pass it.
3018 */
3019 vfs_coredump(siginfo: &ksig->info);
3020 }
3021
3022 /*
3023 * PF_USER_WORKER threads will catch and exit on fatal signals
3024 * themselves. They have cleanup that must be performed, so we
3025 * cannot call do_exit() on their behalf. Note that ksig won't
3026 * be properly initialized, PF_USER_WORKER's shouldn't use it.
3027 */
3028 if (current->flags & PF_USER_WORKER)
3029 goto out;
3030
3031 /*
3032 * Death signals, no core dump.
3033 */
3034 do_group_exit(signr);
3035 /* NOTREACHED */
3036 }
3037 spin_unlock_irq(lock: &sighand->siglock);
3038
3039 ksig->sig = signr;
3040
3041 if (signr && !(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
3042 hide_si_addr_tag_bits(ksig);
3043out:
3044 return signr > 0;
3045}
3046
3047/**
3048 * signal_delivered - called after signal delivery to update blocked signals
3049 * @ksig: kernel signal struct
3050 * @stepping: nonzero if debugger single-step or block-step in use
3051 *
3052 * This function should be called when a signal has successfully been
3053 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
3054 * is always blocked), and the signal itself is blocked unless %SA_NODEFER
3055 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
3056 */
3057static void signal_delivered(struct ksignal *ksig, int stepping)
3058{
3059 sigset_t blocked;
3060
3061 /* A signal was successfully delivered, and the
3062 saved sigmask was stored on the signal frame,
3063 and will be restored by sigreturn. So we can
3064 simply clear the restore sigmask flag. */
3065 clear_restore_sigmask();
3066
3067 sigorsets(r: &blocked, a: &current->blocked, b: &ksig->ka.sa.sa_mask);
3068 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
3069 sigaddset(set: &blocked, sig: ksig->sig);
3070 set_current_blocked(&blocked);
3071 if (current->sas_ss_flags & SS_AUTODISARM)
3072 sas_ss_reset(current);
3073 if (stepping)
3074 ptrace_notify(SIGTRAP, message: 0);
3075}
3076
3077void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
3078{
3079 if (failed)
3080 force_sigsegv(sig: ksig->sig);
3081 else
3082 signal_delivered(ksig, stepping);
3083}
3084
3085/*
3086 * It could be that complete_signal() picked us to notify about the
3087 * group-wide signal. Other threads should be notified now to take
3088 * the shared signals in @which since we will not.
3089 */
3090static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
3091{
3092 sigset_t retarget;
3093 struct task_struct *t;
3094
3095 sigandsets(r: &retarget, a: &tsk->signal->shared_pending.signal, b: which);
3096 if (sigisemptyset(set: &retarget))
3097 return;
3098
3099 for_other_threads(tsk, t) {
3100 if (t->flags & PF_EXITING)
3101 continue;
3102
3103 if (!has_pending_signals(signal: &retarget, blocked: &t->blocked))
3104 continue;
3105 /* Remove the signals this thread can handle. */
3106 sigandsets(r: &retarget, a: &retarget, b: &t->blocked);
3107
3108 if (!task_sigpending(p: t))
3109 signal_wake_up(t, fatal: 0);
3110
3111 if (sigisemptyset(set: &retarget))
3112 break;
3113 }
3114}
3115
3116void exit_signals(struct task_struct *tsk)
3117{
3118 int group_stop = 0;
3119 sigset_t unblocked;
3120
3121 /*
3122 * @tsk is about to have PF_EXITING set - lock out users which
3123 * expect stable threadgroup.
3124 */
3125 cgroup_threadgroup_change_begin(tsk);
3126
3127 if (thread_group_empty(p: tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
3128 sched_mm_cid_exit_signals(t: tsk);
3129 tsk->flags |= PF_EXITING;
3130 cgroup_threadgroup_change_end(tsk);
3131 return;
3132 }
3133
3134 spin_lock_irq(lock: &tsk->sighand->siglock);
3135 /*
3136 * From now this task is not visible for group-wide signals,
3137 * see wants_signal(), do_signal_stop().
3138 */
3139 sched_mm_cid_exit_signals(t: tsk);
3140 tsk->flags |= PF_EXITING;
3141
3142 cgroup_threadgroup_change_end(tsk);
3143
3144 if (!task_sigpending(p: tsk))
3145 goto out;
3146
3147 unblocked = tsk->blocked;
3148 signotset(set: &unblocked);
3149 retarget_shared_pending(tsk, which: &unblocked);
3150
3151 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3152 task_participate_group_stop(task: tsk))
3153 group_stop = CLD_STOPPED;
3154out:
3155 spin_unlock_irq(lock: &tsk->sighand->siglock);
3156
3157 /*
3158 * If group stop has completed, deliver the notification. This
3159 * should always go to the real parent of the group leader.
3160 */
3161 if (unlikely(group_stop)) {
3162 read_lock(&tasklist_lock);
3163 do_notify_parent_cldstop(tsk, for_ptracer: false, why: group_stop);
3164 read_unlock(&tasklist_lock);
3165 }
3166}
3167
3168/*
3169 * System call entry points.
3170 */
3171
3172/**
3173 * sys_restart_syscall - restart a system call
3174 */
3175SYSCALL_DEFINE0(restart_syscall)
3176{
3177 struct restart_block *restart = &current->restart_block;
3178 return restart->fn(restart);
3179}
3180
3181long do_no_restart_syscall(struct restart_block *param)
3182{
3183 return -EINTR;
3184}
3185
3186static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3187{
3188 if (task_sigpending(p: tsk) && !thread_group_empty(p: tsk)) {
3189 sigset_t newblocked;
3190 /* A set of now blocked but previously unblocked signals. */
3191 sigandnsets(r: &newblocked, a: newset, b: &current->blocked);
3192 retarget_shared_pending(tsk, which: &newblocked);
3193 }
3194 tsk->blocked = *newset;
3195 recalc_sigpending();
3196}
3197
3198/**
3199 * set_current_blocked - change current->blocked mask
3200 * @newset: new mask
3201 *
3202 * It is wrong to change ->blocked directly, this helper should be used
3203 * to ensure the process can't miss a shared signal we are going to block.
3204 */
3205void set_current_blocked(sigset_t *newset)
3206{
3207 sigdelsetmask(set: newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3208 __set_current_blocked(newset);
3209}
3210
3211void __set_current_blocked(const sigset_t *newset)
3212{
3213 struct task_struct *tsk = current;
3214
3215 /*
3216 * In case the signal mask hasn't changed, there is nothing we need
3217 * to do. The current->blocked shouldn't be modified by other task.
3218 */
3219 if (sigequalsets(set1: &tsk->blocked, set2: newset))
3220 return;
3221
3222 spin_lock_irq(lock: &tsk->sighand->siglock);
3223 __set_task_blocked(tsk, newset);
3224 spin_unlock_irq(lock: &tsk->sighand->siglock);
3225}
3226
3227/*
3228 * This is also useful for kernel threads that want to temporarily
3229 * (or permanently) block certain signals.
3230 *
3231 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3232 * interface happily blocks "unblockable" signals like SIGKILL
3233 * and friends.
3234 */
3235int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3236{
3237 struct task_struct *tsk = current;
3238 sigset_t newset;
3239
3240 /* Lockless, only current can change ->blocked, never from irq */
3241 if (oldset)
3242 *oldset = tsk->blocked;
3243
3244 switch (how) {
3245 case SIG_BLOCK:
3246 sigorsets(r: &newset, a: &tsk->blocked, b: set);
3247 break;
3248 case SIG_UNBLOCK:
3249 sigandnsets(r: &newset, a: &tsk->blocked, b: set);
3250 break;
3251 case SIG_SETMASK:
3252 newset = *set;
3253 break;
3254 default:
3255 return -EINVAL;
3256 }
3257
3258 __set_current_blocked(newset: &newset);
3259 return 0;
3260}
3261EXPORT_SYMBOL(sigprocmask);
3262
3263/*
3264 * The api helps set app-provided sigmasks.
3265 *
3266 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3267 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3268 *
3269 * Note that it does set_restore_sigmask() in advance, so it must be always
3270 * paired with restore_saved_sigmask_unless() before return from syscall.
3271 */
3272int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3273{
3274 sigset_t kmask;
3275
3276 if (!umask)
3277 return 0;
3278 if (sigsetsize != sizeof(sigset_t))
3279 return -EINVAL;
3280 if (copy_from_user(to: &kmask, from: umask, n: sizeof(sigset_t)))
3281 return -EFAULT;
3282
3283 set_restore_sigmask();
3284 current->saved_sigmask = current->blocked;
3285 set_current_blocked(&kmask);
3286
3287 return 0;
3288}
3289
3290#ifdef CONFIG_COMPAT
3291int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3292 size_t sigsetsize)
3293{
3294 sigset_t kmask;
3295
3296 if (!umask)
3297 return 0;
3298 if (sigsetsize != sizeof(compat_sigset_t))
3299 return -EINVAL;
3300 if (get_compat_sigset(set: &kmask, compat: umask))
3301 return -EFAULT;
3302
3303 set_restore_sigmask();
3304 current->saved_sigmask = current->blocked;
3305 set_current_blocked(&kmask);
3306
3307 return 0;
3308}
3309#endif
3310
3311/**
3312 * sys_rt_sigprocmask - change the list of currently blocked signals
3313 * @how: whether to add, remove, or set signals
3314 * @nset: stores pending signals
3315 * @oset: previous value of signal mask if non-null
3316 * @sigsetsize: size of sigset_t type
3317 */
3318SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3319 sigset_t __user *, oset, size_t, sigsetsize)
3320{
3321 sigset_t old_set, new_set;
3322 int error;
3323
3324 /* XXX: Don't preclude handling different sized sigset_t's. */
3325 if (sigsetsize != sizeof(sigset_t))
3326 return -EINVAL;
3327
3328 old_set = current->blocked;
3329
3330 if (nset) {
3331 if (copy_from_user(to: &new_set, from: nset, n: sizeof(sigset_t)))
3332 return -EFAULT;
3333 sigdelsetmask(set: &new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3334
3335 error = sigprocmask(how, &new_set, NULL);
3336 if (error)
3337 return error;
3338 }
3339
3340 if (oset) {
3341 if (copy_to_user(to: oset, from: &old_set, n: sizeof(sigset_t)))
3342 return -EFAULT;
3343 }
3344
3345 return 0;
3346}
3347
3348#ifdef CONFIG_COMPAT
3349COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3350 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3351{
3352 sigset_t old_set = current->blocked;
3353
3354 /* XXX: Don't preclude handling different sized sigset_t's. */
3355 if (sigsetsize != sizeof(sigset_t))
3356 return -EINVAL;
3357
3358 if (nset) {
3359 sigset_t new_set;
3360 int error;
3361 if (get_compat_sigset(set: &new_set, compat: nset))
3362 return -EFAULT;
3363 sigdelsetmask(set: &new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3364
3365 error = sigprocmask(how, &new_set, NULL);
3366 if (error)
3367 return error;
3368 }
3369 return oset ? put_compat_sigset(compat: oset, set: &old_set, size: sizeof(*oset)) : 0;
3370}
3371#endif
3372
3373static void do_sigpending(sigset_t *set)
3374{
3375 spin_lock_irq(lock: &current->sighand->siglock);
3376 sigorsets(r: set, a: &current->pending.signal,
3377 b: &current->signal->shared_pending.signal);
3378 spin_unlock_irq(lock: &current->sighand->siglock);
3379
3380 /* Outside the lock because only this thread touches it. */
3381 sigandsets(r: set, a: &current->blocked, b: set);
3382}
3383
3384/**
3385 * sys_rt_sigpending - examine a pending signal that has been raised
3386 * while blocked
3387 * @uset: stores pending signals
3388 * @sigsetsize: size of sigset_t type or larger
3389 */
3390SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3391{
3392 sigset_t set;
3393
3394 if (sigsetsize > sizeof(*uset))
3395 return -EINVAL;
3396
3397 do_sigpending(set: &set);
3398
3399 if (copy_to_user(to: uset, from: &set, n: sigsetsize))
3400 return -EFAULT;
3401
3402 return 0;
3403}
3404
3405#ifdef CONFIG_COMPAT
3406COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3407 compat_size_t, sigsetsize)
3408{
3409 sigset_t set;
3410
3411 if (sigsetsize > sizeof(*uset))
3412 return -EINVAL;
3413
3414 do_sigpending(set: &set);
3415
3416 return put_compat_sigset(compat: uset, set: &set, size: sigsetsize);
3417}
3418#endif
3419
3420static const struct {
3421 unsigned char limit, layout;
3422} sig_sicodes[] = {
3423 [SIGILL] = { NSIGILL, SIL_FAULT },
3424 [SIGFPE] = { NSIGFPE, .layout: SIL_FAULT },
3425 [SIGSEGV] = { NSIGSEGV, .layout: SIL_FAULT },
3426 [SIGBUS] = { NSIGBUS, .layout: SIL_FAULT },
3427 [SIGTRAP] = { NSIGTRAP, .layout: SIL_FAULT },
3428#if defined(SIGEMT)
3429 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3430#endif
3431 [SIGCHLD] = { NSIGCHLD, .layout: SIL_CHLD },
3432 [SIGPOLL] = { NSIGPOLL, .layout: SIL_POLL },
3433 [SIGSYS] = { NSIGSYS, .layout: SIL_SYS },
3434};
3435
3436static bool known_siginfo_layout(unsigned sig, int si_code)
3437{
3438 if (si_code == SI_KERNEL)
3439 return true;
3440 else if ((si_code > SI_USER)) {
3441 if (sig_specific_sicodes(sig)) {
3442 if (si_code <= sig_sicodes[sig].limit)
3443 return true;
3444 }
3445 else if (si_code <= NSIGPOLL)
3446 return true;
3447 }
3448 else if (si_code >= SI_DETHREAD)
3449 return true;
3450 else if (si_code == SI_ASYNCNL)
3451 return true;
3452 return false;
3453}
3454
3455enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3456{
3457 enum siginfo_layout layout = SIL_KILL;
3458 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3459 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3460 (si_code <= sig_sicodes[sig].limit)) {
3461 layout = sig_sicodes[sig].layout;
3462 /* Handle the exceptions */
3463 if ((sig == SIGBUS) &&
3464 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3465 layout = SIL_FAULT_MCEERR;
3466 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3467 layout = SIL_FAULT_BNDERR;
3468#ifdef SEGV_PKUERR
3469 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3470 layout = SIL_FAULT_PKUERR;
3471#endif
3472 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3473 layout = SIL_FAULT_PERF_EVENT;
3474 else if (IS_ENABLED(CONFIG_SPARC) &&
3475 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3476 layout = SIL_FAULT_TRAPNO;
3477 else if (IS_ENABLED(CONFIG_ALPHA) &&
3478 ((sig == SIGFPE) ||
3479 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3480 layout = SIL_FAULT_TRAPNO;
3481 }
3482 else if (si_code <= NSIGPOLL)
3483 layout = SIL_POLL;
3484 } else {
3485 if (si_code == SI_TIMER)
3486 layout = SIL_TIMER;
3487 else if (si_code == SI_SIGIO)
3488 layout = SIL_POLL;
3489 else if (si_code < 0)
3490 layout = SIL_RT;
3491 }
3492 return layout;
3493}
3494
3495static inline char __user *si_expansion(const siginfo_t __user *info)
3496{
3497 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3498}
3499
3500int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3501{
3502 char __user *expansion = si_expansion(info: to);
3503 if (copy_to_user(to, from , n: sizeof(struct kernel_siginfo)))
3504 return -EFAULT;
3505 if (clear_user(to: expansion, SI_EXPANSION_SIZE))
3506 return -EFAULT;
3507 return 0;
3508}
3509
3510static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3511 const siginfo_t __user *from)
3512{
3513 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3514 char __user *expansion = si_expansion(info: from);
3515 char buf[SI_EXPANSION_SIZE];
3516 int i;
3517 /*
3518 * An unknown si_code might need more than
3519 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3520 * extra bytes are 0. This guarantees copy_siginfo_to_user
3521 * will return this data to userspace exactly.
3522 */
3523 if (copy_from_user(to: &buf, from: expansion, SI_EXPANSION_SIZE))
3524 return -EFAULT;
3525 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3526 if (buf[i] != 0)
3527 return -E2BIG;
3528 }
3529 }
3530 return 0;
3531}
3532
3533static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3534 const siginfo_t __user *from)
3535{
3536 if (copy_from_user(to, from, n: sizeof(struct kernel_siginfo)))
3537 return -EFAULT;
3538 to->si_signo = signo;
3539 return post_copy_siginfo_from_user(info: to, from);
3540}
3541
3542int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3543{
3544 if (copy_from_user(to, from, n: sizeof(struct kernel_siginfo)))
3545 return -EFAULT;
3546 return post_copy_siginfo_from_user(info: to, from);
3547}
3548
3549#ifdef CONFIG_COMPAT
3550/**
3551 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3552 * @to: compat siginfo destination
3553 * @from: kernel siginfo source
3554 *
3555 * Note: This function does not work properly for the SIGCHLD on x32, but
3556 * fortunately it doesn't have to. The only valid callers for this function are
3557 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3558 * The latter does not care because SIGCHLD will never cause a coredump.
3559 */
3560void copy_siginfo_to_external32(struct compat_siginfo *to,
3561 const struct kernel_siginfo *from)
3562{
3563 memset(s: to, c: 0, n: sizeof(*to));
3564
3565 to->si_signo = from->si_signo;
3566 to->si_errno = from->si_errno;
3567 to->si_code = from->si_code;
3568 switch(siginfo_layout(sig: from->si_signo, si_code: from->si_code)) {
3569 case SIL_KILL:
3570 to->si_pid = from->si_pid;
3571 to->si_uid = from->si_uid;
3572 break;
3573 case SIL_TIMER:
3574 to->si_tid = from->si_tid;
3575 to->si_overrun = from->si_overrun;
3576 to->si_int = from->si_int;
3577 break;
3578 case SIL_POLL:
3579 to->si_band = from->si_band;
3580 to->si_fd = from->si_fd;
3581 break;
3582 case SIL_FAULT:
3583 to->si_addr = ptr_to_compat(uptr: from->si_addr);
3584 break;
3585 case SIL_FAULT_TRAPNO:
3586 to->si_addr = ptr_to_compat(uptr: from->si_addr);
3587 to->si_trapno = from->si_trapno;
3588 break;
3589 case SIL_FAULT_MCEERR:
3590 to->si_addr = ptr_to_compat(uptr: from->si_addr);
3591 to->si_addr_lsb = from->si_addr_lsb;
3592 break;
3593 case SIL_FAULT_BNDERR:
3594 to->si_addr = ptr_to_compat(uptr: from->si_addr);
3595 to->si_lower = ptr_to_compat(uptr: from->si_lower);
3596 to->si_upper = ptr_to_compat(uptr: from->si_upper);
3597 break;
3598 case SIL_FAULT_PKUERR:
3599 to->si_addr = ptr_to_compat(uptr: from->si_addr);
3600 to->si_pkey = from->si_pkey;
3601 break;
3602 case SIL_FAULT_PERF_EVENT:
3603 to->si_addr = ptr_to_compat(uptr: from->si_addr);
3604 to->si_perf_data = from->si_perf_data;
3605 to->si_perf_type = from->si_perf_type;
3606 to->si_perf_flags = from->si_perf_flags;
3607 break;
3608 case SIL_CHLD:
3609 to->si_pid = from->si_pid;
3610 to->si_uid = from->si_uid;
3611 to->si_status = from->si_status;
3612 to->si_utime = from->si_utime;
3613 to->si_stime = from->si_stime;
3614 break;
3615 case SIL_RT:
3616 to->si_pid = from->si_pid;
3617 to->si_uid = from->si_uid;
3618 to->si_int = from->si_int;
3619 break;
3620 case SIL_SYS:
3621 to->si_call_addr = ptr_to_compat(uptr: from->si_call_addr);
3622 to->si_syscall = from->si_syscall;
3623 to->si_arch = from->si_arch;
3624 break;
3625 }
3626}
3627
3628int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3629 const struct kernel_siginfo *from)
3630{
3631 struct compat_siginfo new;
3632
3633 copy_siginfo_to_external32(to: &new, from);
3634 if (copy_to_user(to, from: &new, n: sizeof(struct compat_siginfo)))
3635 return -EFAULT;
3636 return 0;
3637}
3638
3639static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3640 const struct compat_siginfo *from)
3641{
3642 clear_siginfo(info: to);
3643 to->si_signo = from->si_signo;
3644 to->si_errno = from->si_errno;
3645 to->si_code = from->si_code;
3646 switch(siginfo_layout(sig: from->si_signo, si_code: from->si_code)) {
3647 case SIL_KILL:
3648 to->si_pid = from->si_pid;
3649 to->si_uid = from->si_uid;
3650 break;
3651 case SIL_TIMER:
3652 to->si_tid = from->si_tid;
3653 to->si_overrun = from->si_overrun;
3654 to->si_int = from->si_int;
3655 break;
3656 case SIL_POLL:
3657 to->si_band = from->si_band;
3658 to->si_fd = from->si_fd;
3659 break;
3660 case SIL_FAULT:
3661 to->si_addr = compat_ptr(uptr: from->si_addr);
3662 break;
3663 case SIL_FAULT_TRAPNO:
3664 to->si_addr = compat_ptr(uptr: from->si_addr);
3665 to->si_trapno = from->si_trapno;
3666 break;
3667 case SIL_FAULT_MCEERR:
3668 to->si_addr = compat_ptr(uptr: from->si_addr);
3669 to->si_addr_lsb = from->si_addr_lsb;
3670 break;
3671 case SIL_FAULT_BNDERR:
3672 to->si_addr = compat_ptr(uptr: from->si_addr);
3673 to->si_lower = compat_ptr(uptr: from->si_lower);
3674 to->si_upper = compat_ptr(uptr: from->si_upper);
3675 break;
3676 case SIL_FAULT_PKUERR:
3677 to->si_addr = compat_ptr(uptr: from->si_addr);
3678 to->si_pkey = from->si_pkey;
3679 break;
3680 case SIL_FAULT_PERF_EVENT:
3681 to->si_addr = compat_ptr(uptr: from->si_addr);
3682 to->si_perf_data = from->si_perf_data;
3683 to->si_perf_type = from->si_perf_type;
3684 to->si_perf_flags = from->si_perf_flags;
3685 break;
3686 case SIL_CHLD:
3687 to->si_pid = from->si_pid;
3688 to->si_uid = from->si_uid;
3689 to->si_status = from->si_status;
3690#ifdef CONFIG_X86_X32_ABI
3691 if (in_x32_syscall()) {
3692 to->si_utime = from->_sifields._sigchld_x32._utime;
3693 to->si_stime = from->_sifields._sigchld_x32._stime;
3694 } else
3695#endif
3696 {
3697 to->si_utime = from->si_utime;
3698 to->si_stime = from->si_stime;
3699 }
3700 break;
3701 case SIL_RT:
3702 to->si_pid = from->si_pid;
3703 to->si_uid = from->si_uid;
3704 to->si_int = from->si_int;
3705 break;
3706 case SIL_SYS:
3707 to->si_call_addr = compat_ptr(uptr: from->si_call_addr);
3708 to->si_syscall = from->si_syscall;
3709 to->si_arch = from->si_arch;
3710 break;
3711 }
3712 return 0;
3713}
3714
3715static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3716 const struct compat_siginfo __user *ufrom)
3717{
3718 struct compat_siginfo from;
3719
3720 if (copy_from_user(to: &from, from: ufrom, n: sizeof(struct compat_siginfo)))
3721 return -EFAULT;
3722
3723 from.si_signo = signo;
3724 return post_copy_siginfo_from_user32(to, from: &from);
3725}
3726
3727int copy_siginfo_from_user32(struct kernel_siginfo *to,
3728 const struct compat_siginfo __user *ufrom)
3729{
3730 struct compat_siginfo from;
3731
3732 if (copy_from_user(to: &from, from: ufrom, n: sizeof(struct compat_siginfo)))
3733 return -EFAULT;
3734
3735 return post_copy_siginfo_from_user32(to, from: &from);
3736}
3737#endif /* CONFIG_COMPAT */
3738
3739/**
3740 * do_sigtimedwait - wait for queued signals specified in @which
3741 * @which: queued signals to wait for
3742 * @info: if non-null, the signal's siginfo is returned here
3743 * @ts: upper bound on process time suspension
3744 */
3745static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3746 const struct timespec64 *ts)
3747{
3748 ktime_t *to = NULL, timeout = KTIME_MAX;
3749 struct task_struct *tsk = current;
3750 sigset_t mask = *which;
3751 enum pid_type type;
3752 int sig, ret = 0;
3753
3754 if (ts) {
3755 if (!timespec64_valid(ts))
3756 return -EINVAL;
3757 timeout = timespec64_to_ktime(ts: *ts);
3758 to = &timeout;
3759 }
3760
3761 /*
3762 * Invert the set of allowed signals to get those we want to block.
3763 */
3764 sigdelsetmask(set: &mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3765 signotset(set: &mask);
3766
3767 spin_lock_irq(lock: &tsk->sighand->siglock);
3768 sig = dequeue_signal(&mask, info, &type);
3769 if (!sig && timeout) {
3770 /*
3771 * None ready, temporarily unblock those we're interested
3772 * while we are sleeping in so that we'll be awakened when
3773 * they arrive. Unblocking is always fine, we can avoid
3774 * set_current_blocked().
3775 */
3776 tsk->real_blocked = tsk->blocked;
3777 sigandsets(r: &tsk->blocked, a: &tsk->blocked, b: &mask);
3778 recalc_sigpending();
3779 spin_unlock_irq(lock: &tsk->sighand->siglock);
3780
3781 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3782 ret = schedule_hrtimeout_range(expires: to, delta: tsk->timer_slack_ns,
3783 mode: HRTIMER_MODE_REL);
3784 spin_lock_irq(lock: &tsk->sighand->siglock);
3785 __set_task_blocked(tsk, newset: &tsk->real_blocked);
3786 sigemptyset(set: &tsk->real_blocked);
3787 sig = dequeue_signal(&mask, info, &type);
3788 }
3789 spin_unlock_irq(lock: &tsk->sighand->siglock);
3790
3791 if (sig)
3792 return sig;
3793 return ret ? -EINTR : -EAGAIN;
3794}
3795
3796/**
3797 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3798 * in @uthese
3799 * @uthese: queued signals to wait for
3800 * @uinfo: if non-null, the signal's siginfo is returned here
3801 * @uts: upper bound on process time suspension
3802 * @sigsetsize: size of sigset_t type
3803 */
3804SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3805 siginfo_t __user *, uinfo,
3806 const struct __kernel_timespec __user *, uts,
3807 size_t, sigsetsize)
3808{
3809 sigset_t these;
3810 struct timespec64 ts;
3811 kernel_siginfo_t info;
3812 int ret;
3813
3814 /* XXX: Don't preclude handling different sized sigset_t's. */
3815 if (sigsetsize != sizeof(sigset_t))
3816 return -EINVAL;
3817
3818 if (copy_from_user(to: &these, from: uthese, n: sizeof(these)))
3819 return -EFAULT;
3820
3821 if (uts) {
3822 if (get_timespec64(ts: &ts, uts))
3823 return -EFAULT;
3824 }
3825
3826 ret = do_sigtimedwait(which: &these, info: &info, ts: uts ? &ts : NULL);
3827
3828 if (ret > 0 && uinfo) {
3829 if (copy_siginfo_to_user(to: uinfo, from: &info))
3830 ret = -EFAULT;
3831 }
3832
3833 return ret;
3834}
3835
3836#ifdef CONFIG_COMPAT_32BIT_TIME
3837SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3838 siginfo_t __user *, uinfo,
3839 const struct old_timespec32 __user *, uts,
3840 size_t, sigsetsize)
3841{
3842 sigset_t these;
3843 struct timespec64 ts;
3844 kernel_siginfo_t info;
3845 int ret;
3846
3847 if (sigsetsize != sizeof(sigset_t))
3848 return -EINVAL;
3849
3850 if (copy_from_user(to: &these, from: uthese, n: sizeof(these)))
3851 return -EFAULT;
3852
3853 if (uts) {
3854 if (get_old_timespec32(&ts, uts))
3855 return -EFAULT;
3856 }
3857
3858 ret = do_sigtimedwait(which: &these, info: &info, ts: uts ? &ts : NULL);
3859
3860 if (ret > 0 && uinfo) {
3861 if (copy_siginfo_to_user(to: uinfo, from: &info))
3862 ret = -EFAULT;
3863 }
3864
3865 return ret;
3866}
3867#endif
3868
3869#ifdef CONFIG_COMPAT
3870COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3871 struct compat_siginfo __user *, uinfo,
3872 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3873{
3874 sigset_t s;
3875 struct timespec64 t;
3876 kernel_siginfo_t info;
3877 long ret;
3878
3879 if (sigsetsize != sizeof(sigset_t))
3880 return -EINVAL;
3881
3882 if (get_compat_sigset(set: &s, compat: uthese))
3883 return -EFAULT;
3884
3885 if (uts) {
3886 if (get_timespec64(ts: &t, uts))
3887 return -EFAULT;
3888 }
3889
3890 ret = do_sigtimedwait(which: &s, info: &info, ts: uts ? &t : NULL);
3891
3892 if (ret > 0 && uinfo) {
3893 if (copy_siginfo_to_user32(to: uinfo, from: &info))
3894 ret = -EFAULT;
3895 }
3896
3897 return ret;
3898}
3899
3900#ifdef CONFIG_COMPAT_32BIT_TIME
3901COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3902 struct compat_siginfo __user *, uinfo,
3903 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3904{
3905 sigset_t s;
3906 struct timespec64 t;
3907 kernel_siginfo_t info;
3908 long ret;
3909
3910 if (sigsetsize != sizeof(sigset_t))
3911 return -EINVAL;
3912
3913 if (get_compat_sigset(set: &s, compat: uthese))
3914 return -EFAULT;
3915
3916 if (uts) {
3917 if (get_old_timespec32(&t, uts))
3918 return -EFAULT;
3919 }
3920
3921 ret = do_sigtimedwait(which: &s, info: &info, ts: uts ? &t : NULL);
3922
3923 if (ret > 0 && uinfo) {
3924 if (copy_siginfo_to_user32(to: uinfo, from: &info))
3925 ret = -EFAULT;
3926 }
3927
3928 return ret;
3929}
3930#endif
3931#endif
3932
3933static void prepare_kill_siginfo(int sig, struct kernel_siginfo *info,
3934 enum pid_type type)
3935{
3936 clear_siginfo(info);
3937 info->si_signo = sig;
3938 info->si_errno = 0;
3939 info->si_code = (type == PIDTYPE_PID) ? SI_TKILL : SI_USER;
3940 info->si_pid = task_tgid_vnr(current);
3941 info->si_uid = from_kuid_munged(to: current_user_ns(), current_uid());
3942}
3943
3944/**
3945 * sys_kill - send a signal to a process
3946 * @pid: the PID of the process
3947 * @sig: signal to be sent
3948 */
3949SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3950{
3951 struct kernel_siginfo info;
3952
3953 prepare_kill_siginfo(sig, info: &info, type: PIDTYPE_TGID);
3954
3955 return kill_something_info(sig, info: &info, pid);
3956}
3957
3958/*
3959 * Verify that the signaler and signalee either are in the same pid namespace
3960 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3961 * namespace.
3962 */
3963static bool access_pidfd_pidns(struct pid *pid)
3964{
3965 struct pid_namespace *active = task_active_pid_ns(current);
3966 struct pid_namespace *p = ns_of_pid(pid);
3967
3968 for (;;) {
3969 if (!p)
3970 return false;
3971 if (p == active)
3972 break;
3973 p = p->parent;
3974 }
3975
3976 return true;
3977}
3978
3979static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3980 siginfo_t __user *info)
3981{
3982#ifdef CONFIG_COMPAT
3983 /*
3984 * Avoid hooking up compat syscalls and instead handle necessary
3985 * conversions here. Note, this is a stop-gap measure and should not be
3986 * considered a generic solution.
3987 */
3988 if (in_compat_syscall())
3989 return copy_siginfo_from_user32(
3990 to: kinfo, ufrom: (struct compat_siginfo __user *)info);
3991#endif
3992 return copy_siginfo_from_user(to: kinfo, from: info);
3993}
3994
3995static struct pid *pidfd_to_pid(const struct file *file)
3996{
3997 struct pid *pid;
3998
3999 pid = pidfd_pid(file);
4000 if (!IS_ERR(ptr: pid))
4001 return pid;
4002
4003 return tgid_pidfd_to_pid(file);
4004}
4005
4006#define PIDFD_SEND_SIGNAL_FLAGS \
4007 (PIDFD_SIGNAL_THREAD | PIDFD_SIGNAL_THREAD_GROUP | \
4008 PIDFD_SIGNAL_PROCESS_GROUP)
4009
4010static int do_pidfd_send_signal(struct pid *pid, int sig, enum pid_type type,
4011 siginfo_t __user *info, unsigned int flags)
4012{
4013 kernel_siginfo_t kinfo;
4014
4015 switch (flags) {
4016 case PIDFD_SIGNAL_THREAD:
4017 type = PIDTYPE_PID;
4018 break;
4019 case PIDFD_SIGNAL_THREAD_GROUP:
4020 type = PIDTYPE_TGID;
4021 break;
4022 case PIDFD_SIGNAL_PROCESS_GROUP:
4023 type = PIDTYPE_PGID;
4024 break;
4025 }
4026
4027 if (info) {
4028 int ret;
4029
4030 ret = copy_siginfo_from_user_any(kinfo: &kinfo, info);
4031 if (unlikely(ret))
4032 return ret;
4033
4034 if (unlikely(sig != kinfo.si_signo))
4035 return -EINVAL;
4036
4037 /* Only allow sending arbitrary signals to yourself. */
4038 if ((task_pid(current) != pid || type > PIDTYPE_TGID) &&
4039 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
4040 return -EPERM;
4041 } else {
4042 prepare_kill_siginfo(sig, info: &kinfo, type);
4043 }
4044
4045 if (type == PIDTYPE_PGID)
4046 return kill_pgrp_info(sig, info: &kinfo, pgrp: pid);
4047
4048 return kill_pid_info_type(sig, info: &kinfo, pid, type);
4049}
4050
4051/**
4052 * sys_pidfd_send_signal - Signal a process through a pidfd
4053 * @pidfd: file descriptor of the process
4054 * @sig: signal to send
4055 * @info: signal info
4056 * @flags: future flags
4057 *
4058 * Send the signal to the thread group or to the individual thread depending
4059 * on PIDFD_THREAD.
4060 * In the future extension to @flags may be used to override the default scope
4061 * of @pidfd.
4062 *
4063 * Return: 0 on success, negative errno on failure
4064 */
4065SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
4066 siginfo_t __user *, info, unsigned int, flags)
4067{
4068 struct pid *pid;
4069 enum pid_type type;
4070 int ret;
4071
4072 /* Enforce flags be set to 0 until we add an extension. */
4073 if (flags & ~PIDFD_SEND_SIGNAL_FLAGS)
4074 return -EINVAL;
4075
4076 /* Ensure that only a single signal scope determining flag is set. */
4077 if (hweight32(flags & PIDFD_SEND_SIGNAL_FLAGS) > 1)
4078 return -EINVAL;
4079
4080 switch (pidfd) {
4081 case PIDFD_SELF_THREAD:
4082 pid = get_task_pid(current, type: PIDTYPE_PID);
4083 type = PIDTYPE_PID;
4084 break;
4085 case PIDFD_SELF_THREAD_GROUP:
4086 pid = get_task_pid(current, type: PIDTYPE_TGID);
4087 type = PIDTYPE_TGID;
4088 break;
4089 default: {
4090 CLASS(fd, f)(fd: pidfd);
4091 if (fd_empty(f))
4092 return -EBADF;
4093
4094 /* Is this a pidfd? */
4095 pid = pidfd_to_pid(fd_file(f));
4096 if (IS_ERR(ptr: pid))
4097 return PTR_ERR(ptr: pid);
4098
4099 if (!access_pidfd_pidns(pid))
4100 return -EINVAL;
4101
4102 /* Infer scope from the type of pidfd. */
4103 if (fd_file(f)->f_flags & PIDFD_THREAD)
4104 type = PIDTYPE_PID;
4105 else
4106 type = PIDTYPE_TGID;
4107
4108 return do_pidfd_send_signal(pid, sig, type, info, flags);
4109 }
4110 }
4111
4112 ret = do_pidfd_send_signal(pid, sig, type, info, flags);
4113 put_pid(pid);
4114
4115 return ret;
4116}
4117
4118static int
4119do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
4120{
4121 struct task_struct *p;
4122 int error = -ESRCH;
4123
4124 rcu_read_lock();
4125 p = find_task_by_vpid(nr: pid);
4126 if (p && (tgid <= 0 || task_tgid_vnr(tsk: p) == tgid)) {
4127 error = check_kill_permission(sig, info, t: p);
4128 /*
4129 * The null signal is a permissions and process existence
4130 * probe. No signal is actually delivered.
4131 */
4132 if (!error && sig) {
4133 error = do_send_sig_info(sig, info, p, type: PIDTYPE_PID);
4134 /*
4135 * If lock_task_sighand() failed we pretend the task
4136 * dies after receiving the signal. The window is tiny,
4137 * and the signal is private anyway.
4138 */
4139 if (unlikely(error == -ESRCH))
4140 error = 0;
4141 }
4142 }
4143 rcu_read_unlock();
4144
4145 return error;
4146}
4147
4148static int do_tkill(pid_t tgid, pid_t pid, int sig)
4149{
4150 struct kernel_siginfo info;
4151
4152 prepare_kill_siginfo(sig, info: &info, type: PIDTYPE_PID);
4153
4154 return do_send_specific(tgid, pid, sig, info: &info);
4155}
4156
4157/**
4158 * sys_tgkill - send signal to one specific thread
4159 * @tgid: the thread group ID of the thread
4160 * @pid: the PID of the thread
4161 * @sig: signal to be sent
4162 *
4163 * This syscall also checks the @tgid and returns -ESRCH even if the PID
4164 * exists but it's not belonging to the target process anymore. This
4165 * method solves the problem of threads exiting and PIDs getting reused.
4166 */
4167SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
4168{
4169 /* This is only valid for single tasks */
4170 if (pid <= 0 || tgid <= 0)
4171 return -EINVAL;
4172
4173 return do_tkill(tgid, pid, sig);
4174}
4175
4176/**
4177 * sys_tkill - send signal to one specific task
4178 * @pid: the PID of the task
4179 * @sig: signal to be sent
4180 *
4181 * Send a signal to only one task, even if it's a CLONE_THREAD task.
4182 */
4183SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4184{
4185 /* This is only valid for single tasks */
4186 if (pid <= 0)
4187 return -EINVAL;
4188
4189 return do_tkill(tgid: 0, pid, sig);
4190}
4191
4192static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4193{
4194 /* Not even root can pretend to send signals from the kernel.
4195 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4196 */
4197 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4198 (task_pid_vnr(current) != pid))
4199 return -EPERM;
4200
4201 /* POSIX.1b doesn't mention process groups. */
4202 return kill_proc_info(sig, info, pid);
4203}
4204
4205/**
4206 * sys_rt_sigqueueinfo - send signal information to a signal
4207 * @pid: the PID of the thread
4208 * @sig: signal to be sent
4209 * @uinfo: signal info to be sent
4210 */
4211SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4212 siginfo_t __user *, uinfo)
4213{
4214 kernel_siginfo_t info;
4215 int ret = __copy_siginfo_from_user(signo: sig, to: &info, from: uinfo);
4216 if (unlikely(ret))
4217 return ret;
4218 return do_rt_sigqueueinfo(pid, sig, info: &info);
4219}
4220
4221#ifdef CONFIG_COMPAT
4222COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4223 compat_pid_t, pid,
4224 int, sig,
4225 struct compat_siginfo __user *, uinfo)
4226{
4227 kernel_siginfo_t info;
4228 int ret = __copy_siginfo_from_user32(signo: sig, to: &info, ufrom: uinfo);
4229 if (unlikely(ret))
4230 return ret;
4231 return do_rt_sigqueueinfo(pid, sig, info: &info);
4232}
4233#endif
4234
4235static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4236{
4237 /* This is only valid for single tasks */
4238 if (pid <= 0 || tgid <= 0)
4239 return -EINVAL;
4240
4241 /* Not even root can pretend to send signals from the kernel.
4242 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4243 */
4244 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4245 (task_pid_vnr(current) != pid))
4246 return -EPERM;
4247
4248 return do_send_specific(tgid, pid, sig, info);
4249}
4250
4251SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4252 siginfo_t __user *, uinfo)
4253{
4254 kernel_siginfo_t info;
4255 int ret = __copy_siginfo_from_user(signo: sig, to: &info, from: uinfo);
4256 if (unlikely(ret))
4257 return ret;
4258 return do_rt_tgsigqueueinfo(tgid, pid, sig, info: &info);
4259}
4260
4261#ifdef CONFIG_COMPAT
4262COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4263 compat_pid_t, tgid,
4264 compat_pid_t, pid,
4265 int, sig,
4266 struct compat_siginfo __user *, uinfo)
4267{
4268 kernel_siginfo_t info;
4269 int ret = __copy_siginfo_from_user32(signo: sig, to: &info, ufrom: uinfo);
4270 if (unlikely(ret))
4271 return ret;
4272 return do_rt_tgsigqueueinfo(tgid, pid, sig, info: &info);
4273}
4274#endif
4275
4276/*
4277 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4278 */
4279void kernel_sigaction(int sig, __sighandler_t action)
4280{
4281 spin_lock_irq(lock: &current->sighand->siglock);
4282 current->sighand->action[sig - 1].sa.sa_handler = action;
4283 if (action == SIG_IGN) {
4284 sigset_t mask;
4285
4286 sigemptyset(set: &mask);
4287 sigaddset(set: &mask, sig: sig);
4288
4289 flush_sigqueue_mask(current, mask: &mask, s: &current->signal->shared_pending);
4290 flush_sigqueue_mask(current, mask: &mask, s: &current->pending);
4291 recalc_sigpending();
4292 }
4293 spin_unlock_irq(lock: &current->sighand->siglock);
4294}
4295EXPORT_SYMBOL(kernel_sigaction);
4296
4297void __weak sigaction_compat_abi(struct k_sigaction *act,
4298 struct k_sigaction *oact)
4299{
4300}
4301
4302int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4303{
4304 struct task_struct *p = current, *t;
4305 struct k_sigaction *k;
4306 sigset_t mask;
4307
4308 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4309 return -EINVAL;
4310
4311 k = &p->sighand->action[sig-1];
4312
4313 spin_lock_irq(lock: &p->sighand->siglock);
4314 if (k->sa.sa_flags & SA_IMMUTABLE) {
4315 spin_unlock_irq(lock: &p->sighand->siglock);
4316 return -EINVAL;
4317 }
4318 if (oact)
4319 *oact = *k;
4320
4321 /*
4322 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4323 * e.g. by having an architecture use the bit in their uapi.
4324 */
4325 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4326
4327 /*
4328 * Clear unknown flag bits in order to allow userspace to detect missing
4329 * support for flag bits and to allow the kernel to use non-uapi bits
4330 * internally.
4331 */
4332 if (act)
4333 act->sa.sa_flags &= UAPI_SA_FLAGS;
4334 if (oact)
4335 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4336
4337 sigaction_compat_abi(act, oact);
4338
4339 if (act) {
4340 bool was_ignored = k->sa.sa_handler == SIG_IGN;
4341
4342 sigdelsetmask(set: &act->sa.sa_mask,
4343 sigmask(SIGKILL) | sigmask(SIGSTOP));
4344 *k = *act;
4345 /*
4346 * POSIX 3.3.1.3:
4347 * "Setting a signal action to SIG_IGN for a signal that is
4348 * pending shall cause the pending signal to be discarded,
4349 * whether or not it is blocked."
4350 *
4351 * "Setting a signal action to SIG_DFL for a signal that is
4352 * pending and whose default action is to ignore the signal
4353 * (for example, SIGCHLD), shall cause the pending signal to
4354 * be discarded, whether or not it is blocked"
4355 */
4356 if (sig_handler_ignored(handler: sig_handler(t: p, sig), sig)) {
4357 sigemptyset(set: &mask);
4358 sigaddset(set: &mask, sig: sig);
4359 flush_sigqueue_mask(p, mask: &mask, s: &p->signal->shared_pending);
4360 for_each_thread(p, t)
4361 flush_sigqueue_mask(p, mask: &mask, s: &t->pending);
4362 } else if (was_ignored) {
4363 posixtimer_sig_unignore(tsk: p, sig);
4364 }
4365 }
4366
4367 spin_unlock_irq(lock: &p->sighand->siglock);
4368 return 0;
4369}
4370
4371#ifdef CONFIG_DYNAMIC_SIGFRAME
4372static inline void sigaltstack_lock(void)
4373 __acquires(&current->sighand->siglock)
4374{
4375 spin_lock_irq(lock: &current->sighand->siglock);
4376}
4377
4378static inline void sigaltstack_unlock(void)
4379 __releases(&current->sighand->siglock)
4380{
4381 spin_unlock_irq(lock: &current->sighand->siglock);
4382}
4383#else
4384static inline void sigaltstack_lock(void) { }
4385static inline void sigaltstack_unlock(void) { }
4386#endif
4387
4388static int
4389do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4390 size_t min_ss_size)
4391{
4392 struct task_struct *t = current;
4393 int ret = 0;
4394
4395 if (oss) {
4396 memset(s: oss, c: 0, n: sizeof(stack_t));
4397 oss->ss_sp = (void __user *) t->sas_ss_sp;
4398 oss->ss_size = t->sas_ss_size;
4399 oss->ss_flags = sas_ss_flags(sp) |
4400 (current->sas_ss_flags & SS_FLAG_BITS);
4401 }
4402
4403 if (ss) {
4404 void __user *ss_sp = ss->ss_sp;
4405 size_t ss_size = ss->ss_size;
4406 unsigned ss_flags = ss->ss_flags;
4407 int ss_mode;
4408
4409 if (unlikely(on_sig_stack(sp)))
4410 return -EPERM;
4411
4412 ss_mode = ss_flags & ~SS_FLAG_BITS;
4413 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4414 ss_mode != 0))
4415 return -EINVAL;
4416
4417 /*
4418 * Return before taking any locks if no actual
4419 * sigaltstack changes were requested.
4420 */
4421 if (t->sas_ss_sp == (unsigned long)ss_sp &&
4422 t->sas_ss_size == ss_size &&
4423 t->sas_ss_flags == ss_flags)
4424 return 0;
4425
4426 sigaltstack_lock();
4427 if (ss_mode == SS_DISABLE) {
4428 ss_size = 0;
4429 ss_sp = NULL;
4430 } else {
4431 if (unlikely(ss_size < min_ss_size))
4432 ret = -ENOMEM;
4433 if (!sigaltstack_size_valid(ss_size))
4434 ret = -ENOMEM;
4435 }
4436 if (!ret) {
4437 t->sas_ss_sp = (unsigned long) ss_sp;
4438 t->sas_ss_size = ss_size;
4439 t->sas_ss_flags = ss_flags;
4440 }
4441 sigaltstack_unlock();
4442 }
4443 return ret;
4444}
4445
4446SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4447{
4448 stack_t new, old;
4449 int err;
4450 if (uss && copy_from_user(to: &new, from: uss, n: sizeof(stack_t)))
4451 return -EFAULT;
4452 err = do_sigaltstack(ss: uss ? &new : NULL, oss: uoss ? &old : NULL,
4453 current_user_stack_pointer(),
4454 MINSIGSTKSZ);
4455 if (!err && uoss && copy_to_user(to: uoss, from: &old, n: sizeof(stack_t)))
4456 err = -EFAULT;
4457 return err;
4458}
4459
4460int restore_altstack(const stack_t __user *uss)
4461{
4462 stack_t new;
4463 if (copy_from_user(to: &new, from: uss, n: sizeof(stack_t)))
4464 return -EFAULT;
4465 (void)do_sigaltstack(ss: &new, NULL, current_user_stack_pointer(),
4466 MINSIGSTKSZ);
4467 /* squash all but EFAULT for now */
4468 return 0;
4469}
4470
4471int __save_altstack(stack_t __user *uss, unsigned long sp)
4472{
4473 struct task_struct *t = current;
4474 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4475 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4476 __put_user(t->sas_ss_size, &uss->ss_size);
4477 return err;
4478}
4479
4480#ifdef CONFIG_COMPAT
4481static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4482 compat_stack_t __user *uoss_ptr)
4483{
4484 stack_t uss, uoss;
4485 int ret;
4486
4487 if (uss_ptr) {
4488 compat_stack_t uss32;
4489 if (copy_from_user(to: &uss32, from: uss_ptr, n: sizeof(compat_stack_t)))
4490 return -EFAULT;
4491 uss.ss_sp = compat_ptr(uptr: uss32.ss_sp);
4492 uss.ss_flags = uss32.ss_flags;
4493 uss.ss_size = uss32.ss_size;
4494 }
4495 ret = do_sigaltstack(ss: uss_ptr ? &uss : NULL, oss: &uoss,
4496 compat_user_stack_pointer(),
4497 COMPAT_MINSIGSTKSZ);
4498 if (ret >= 0 && uoss_ptr) {
4499 compat_stack_t old;
4500 memset(s: &old, c: 0, n: sizeof(old));
4501 old.ss_sp = ptr_to_compat(uptr: uoss.ss_sp);
4502 old.ss_flags = uoss.ss_flags;
4503 old.ss_size = uoss.ss_size;
4504 if (copy_to_user(to: uoss_ptr, from: &old, n: sizeof(compat_stack_t)))
4505 ret = -EFAULT;
4506 }
4507 return ret;
4508}
4509
4510COMPAT_SYSCALL_DEFINE2(sigaltstack,
4511 const compat_stack_t __user *, uss_ptr,
4512 compat_stack_t __user *, uoss_ptr)
4513{
4514 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4515}
4516
4517int compat_restore_altstack(const compat_stack_t __user *uss)
4518{
4519 int err = do_compat_sigaltstack(uss_ptr: uss, NULL);
4520 /* squash all but -EFAULT for now */
4521 return err == -EFAULT ? err : 0;
4522}
4523
4524int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4525{
4526 int err;
4527 struct task_struct *t = current;
4528 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4529 &uss->ss_sp) |
4530 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4531 __put_user(t->sas_ss_size, &uss->ss_size);
4532 return err;
4533}
4534#endif
4535
4536#ifdef __ARCH_WANT_SYS_SIGPENDING
4537
4538/**
4539 * sys_sigpending - examine pending signals
4540 * @uset: where mask of pending signal is returned
4541 */
4542SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4543{
4544 sigset_t set;
4545
4546 if (sizeof(old_sigset_t) > sizeof(*uset))
4547 return -EINVAL;
4548
4549 do_sigpending(set: &set);
4550
4551 if (copy_to_user(to: uset, from: &set, n: sizeof(old_sigset_t)))
4552 return -EFAULT;
4553
4554 return 0;
4555}
4556
4557#ifdef CONFIG_COMPAT
4558COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4559{
4560 sigset_t set;
4561
4562 do_sigpending(set: &set);
4563
4564 return put_user(set.sig[0], set32);
4565}
4566#endif
4567
4568#endif
4569
4570#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4571/**
4572 * sys_sigprocmask - examine and change blocked signals
4573 * @how: whether to add, remove, or set signals
4574 * @nset: signals to add or remove (if non-null)
4575 * @oset: previous value of signal mask if non-null
4576 *
4577 * Some platforms have their own version with special arguments;
4578 * others support only sys_rt_sigprocmask.
4579 */
4580
4581SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4582 old_sigset_t __user *, oset)
4583{
4584 old_sigset_t old_set, new_set;
4585 sigset_t new_blocked;
4586
4587 old_set = current->blocked.sig[0];
4588
4589 if (nset) {
4590 if (copy_from_user(to: &new_set, from: nset, n: sizeof(*nset)))
4591 return -EFAULT;
4592
4593 new_blocked = current->blocked;
4594
4595 switch (how) {
4596 case SIG_BLOCK:
4597 sigaddsetmask(set: &new_blocked, mask: new_set);
4598 break;
4599 case SIG_UNBLOCK:
4600 sigdelsetmask(set: &new_blocked, mask: new_set);
4601 break;
4602 case SIG_SETMASK:
4603 new_blocked.sig[0] = new_set;
4604 break;
4605 default:
4606 return -EINVAL;
4607 }
4608
4609 set_current_blocked(&new_blocked);
4610 }
4611
4612 if (oset) {
4613 if (copy_to_user(to: oset, from: &old_set, n: sizeof(*oset)))
4614 return -EFAULT;
4615 }
4616
4617 return 0;
4618}
4619#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4620
4621#ifndef CONFIG_ODD_RT_SIGACTION
4622/**
4623 * sys_rt_sigaction - alter an action taken by a process
4624 * @sig: signal to be sent
4625 * @act: new sigaction
4626 * @oact: used to save the previous sigaction
4627 * @sigsetsize: size of sigset_t type
4628 */
4629SYSCALL_DEFINE4(rt_sigaction, int, sig,
4630 const struct sigaction __user *, act,
4631 struct sigaction __user *, oact,
4632 size_t, sigsetsize)
4633{
4634 struct k_sigaction new_sa, old_sa;
4635 int ret;
4636
4637 /* XXX: Don't preclude handling different sized sigset_t's. */
4638 if (sigsetsize != sizeof(sigset_t))
4639 return -EINVAL;
4640
4641 if (act && copy_from_user(to: &new_sa.sa, from: act, n: sizeof(new_sa.sa)))
4642 return -EFAULT;
4643
4644 ret = do_sigaction(sig, act: act ? &new_sa : NULL, oact: oact ? &old_sa : NULL);
4645 if (ret)
4646 return ret;
4647
4648 if (oact && copy_to_user(to: oact, from: &old_sa.sa, n: sizeof(old_sa.sa)))
4649 return -EFAULT;
4650
4651 return 0;
4652}
4653#ifdef CONFIG_COMPAT
4654COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4655 const struct compat_sigaction __user *, act,
4656 struct compat_sigaction __user *, oact,
4657 compat_size_t, sigsetsize)
4658{
4659 struct k_sigaction new_ka, old_ka;
4660#ifdef __ARCH_HAS_SA_RESTORER
4661 compat_uptr_t restorer;
4662#endif
4663 int ret;
4664
4665 /* XXX: Don't preclude handling different sized sigset_t's. */
4666 if (sigsetsize != sizeof(compat_sigset_t))
4667 return -EINVAL;
4668
4669 if (act) {
4670 compat_uptr_t handler;
4671 ret = get_user(handler, &act->sa_handler);
4672 new_ka.sa.sa_handler = compat_ptr(uptr: handler);
4673#ifdef __ARCH_HAS_SA_RESTORER
4674 ret |= get_user(restorer, &act->sa_restorer);
4675 new_ka.sa.sa_restorer = compat_ptr(uptr: restorer);
4676#endif
4677 ret |= get_compat_sigset(set: &new_ka.sa.sa_mask, compat: &act->sa_mask);
4678 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4679 if (ret)
4680 return -EFAULT;
4681 }
4682
4683 ret = do_sigaction(sig, act: act ? &new_ka : NULL, oact: oact ? &old_ka : NULL);
4684 if (!ret && oact) {
4685 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4686 &oact->sa_handler);
4687 ret |= put_compat_sigset(compat: &oact->sa_mask, set: &old_ka.sa.sa_mask,
4688 size: sizeof(oact->sa_mask));
4689 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4690#ifdef __ARCH_HAS_SA_RESTORER
4691 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4692 &oact->sa_restorer);
4693#endif
4694 }
4695 return ret;
4696}
4697#endif
4698#endif /* !CONFIG_ODD_RT_SIGACTION */
4699
4700#ifdef CONFIG_OLD_SIGACTION
4701SYSCALL_DEFINE3(sigaction, int, sig,
4702 const struct old_sigaction __user *, act,
4703 struct old_sigaction __user *, oact)
4704{
4705 struct k_sigaction new_ka, old_ka;
4706 int ret;
4707
4708 if (act) {
4709 old_sigset_t mask;
4710 if (!access_ok(act, sizeof(*act)) ||
4711 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4712 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4713 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4714 __get_user(mask, &act->sa_mask))
4715 return -EFAULT;
4716#ifdef __ARCH_HAS_KA_RESTORER
4717 new_ka.ka_restorer = NULL;
4718#endif
4719 siginitset(&new_ka.sa.sa_mask, mask);
4720 }
4721
4722 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4723
4724 if (!ret && oact) {
4725 if (!access_ok(oact, sizeof(*oact)) ||
4726 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4727 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4728 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4729 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4730 return -EFAULT;
4731 }
4732
4733 return ret;
4734}
4735#endif
4736#ifdef CONFIG_COMPAT_OLD_SIGACTION
4737COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4738 const struct compat_old_sigaction __user *, act,
4739 struct compat_old_sigaction __user *, oact)
4740{
4741 struct k_sigaction new_ka, old_ka;
4742 int ret;
4743 compat_old_sigset_t mask;
4744 compat_uptr_t handler, restorer;
4745
4746 if (act) {
4747 if (!access_ok(act, sizeof(*act)) ||
4748 __get_user(handler, &act->sa_handler) ||
4749 __get_user(restorer, &act->sa_restorer) ||
4750 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4751 __get_user(mask, &act->sa_mask))
4752 return -EFAULT;
4753
4754#ifdef __ARCH_HAS_KA_RESTORER
4755 new_ka.ka_restorer = NULL;
4756#endif
4757 new_ka.sa.sa_handler = compat_ptr(uptr: handler);
4758 new_ka.sa.sa_restorer = compat_ptr(uptr: restorer);
4759 siginitset(set: &new_ka.sa.sa_mask, mask);
4760 }
4761
4762 ret = do_sigaction(sig, act: act ? &new_ka : NULL, oact: oact ? &old_ka : NULL);
4763
4764 if (!ret && oact) {
4765 if (!access_ok(oact, sizeof(*oact)) ||
4766 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4767 &oact->sa_handler) ||
4768 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4769 &oact->sa_restorer) ||
4770 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4771 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4772 return -EFAULT;
4773 }
4774 return ret;
4775}
4776#endif
4777
4778#ifdef CONFIG_SGETMASK_SYSCALL
4779
4780/*
4781 * For backwards compatibility. Functionality superseded by sigprocmask.
4782 */
4783SYSCALL_DEFINE0(sgetmask)
4784{
4785 /* SMP safe */
4786 return current->blocked.sig[0];
4787}
4788
4789SYSCALL_DEFINE1(ssetmask, int, newmask)
4790{
4791 int old = current->blocked.sig[0];
4792 sigset_t newset;
4793
4794 siginitset(set: &newset, mask: newmask);
4795 set_current_blocked(&newset);
4796
4797 return old;
4798}
4799#endif /* CONFIG_SGETMASK_SYSCALL */
4800
4801#ifdef __ARCH_WANT_SYS_SIGNAL
4802/*
4803 * For backwards compatibility. Functionality superseded by sigaction.
4804 */
4805SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4806{
4807 struct k_sigaction new_sa, old_sa;
4808 int ret;
4809
4810 new_sa.sa.sa_handler = handler;
4811 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4812 sigemptyset(set: &new_sa.sa.sa_mask);
4813
4814 ret = do_sigaction(sig, act: &new_sa, oact: &old_sa);
4815
4816 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4817}
4818#endif /* __ARCH_WANT_SYS_SIGNAL */
4819
4820#ifdef __ARCH_WANT_SYS_PAUSE
4821
4822SYSCALL_DEFINE0(pause)
4823{
4824 while (!signal_pending(current)) {
4825 __set_current_state(TASK_INTERRUPTIBLE);
4826 schedule();
4827 }
4828 return -ERESTARTNOHAND;
4829}
4830
4831#endif
4832
4833static int sigsuspend(sigset_t *set)
4834{
4835 current->saved_sigmask = current->blocked;
4836 set_current_blocked(set);
4837
4838 while (!signal_pending(current)) {
4839 __set_current_state(TASK_INTERRUPTIBLE);
4840 schedule();
4841 }
4842 set_restore_sigmask();
4843 return -ERESTARTNOHAND;
4844}
4845
4846/**
4847 * sys_rt_sigsuspend - replace the signal mask for a value with the
4848 * @unewset value until a signal is received
4849 * @unewset: new signal mask value
4850 * @sigsetsize: size of sigset_t type
4851 */
4852SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4853{
4854 sigset_t newset;
4855
4856 /* XXX: Don't preclude handling different sized sigset_t's. */
4857 if (sigsetsize != sizeof(sigset_t))
4858 return -EINVAL;
4859
4860 if (copy_from_user(to: &newset, from: unewset, n: sizeof(newset)))
4861 return -EFAULT;
4862 return sigsuspend(set: &newset);
4863}
4864
4865#ifdef CONFIG_COMPAT
4866COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4867{
4868 sigset_t newset;
4869
4870 /* XXX: Don't preclude handling different sized sigset_t's. */
4871 if (sigsetsize != sizeof(sigset_t))
4872 return -EINVAL;
4873
4874 if (get_compat_sigset(set: &newset, compat: unewset))
4875 return -EFAULT;
4876 return sigsuspend(set: &newset);
4877}
4878#endif
4879
4880#ifdef CONFIG_OLD_SIGSUSPEND
4881SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4882{
4883 sigset_t blocked;
4884 siginitset(&blocked, mask);
4885 return sigsuspend(&blocked);
4886}
4887#endif
4888#ifdef CONFIG_OLD_SIGSUSPEND3
4889SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4890{
4891 sigset_t blocked;
4892 siginitset(set: &blocked, mask);
4893 return sigsuspend(set: &blocked);
4894}
4895#endif
4896
4897__weak const char *arch_vma_name(struct vm_area_struct *vma)
4898{
4899 return NULL;
4900}
4901
4902static inline void siginfo_buildtime_checks(void)
4903{
4904 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4905
4906 /* Verify the offsets in the two siginfos match */
4907#define CHECK_OFFSET(field) \
4908 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4909
4910 /* kill */
4911 CHECK_OFFSET(si_pid);
4912 CHECK_OFFSET(si_uid);
4913
4914 /* timer */
4915 CHECK_OFFSET(si_tid);
4916 CHECK_OFFSET(si_overrun);
4917 CHECK_OFFSET(si_value);
4918
4919 /* rt */
4920 CHECK_OFFSET(si_pid);
4921 CHECK_OFFSET(si_uid);
4922 CHECK_OFFSET(si_value);
4923
4924 /* sigchld */
4925 CHECK_OFFSET(si_pid);
4926 CHECK_OFFSET(si_uid);
4927 CHECK_OFFSET(si_status);
4928 CHECK_OFFSET(si_utime);
4929 CHECK_OFFSET(si_stime);
4930
4931 /* sigfault */
4932 CHECK_OFFSET(si_addr);
4933 CHECK_OFFSET(si_trapno);
4934 CHECK_OFFSET(si_addr_lsb);
4935 CHECK_OFFSET(si_lower);
4936 CHECK_OFFSET(si_upper);
4937 CHECK_OFFSET(si_pkey);
4938 CHECK_OFFSET(si_perf_data);
4939 CHECK_OFFSET(si_perf_type);
4940 CHECK_OFFSET(si_perf_flags);
4941
4942 /* sigpoll */
4943 CHECK_OFFSET(si_band);
4944 CHECK_OFFSET(si_fd);
4945
4946 /* sigsys */
4947 CHECK_OFFSET(si_call_addr);
4948 CHECK_OFFSET(si_syscall);
4949 CHECK_OFFSET(si_arch);
4950#undef CHECK_OFFSET
4951
4952 /* usb asyncio */
4953 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4954 offsetof(struct siginfo, si_addr));
4955 if (sizeof(int) == sizeof(void __user *)) {
4956 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4957 sizeof(void __user *));
4958 } else {
4959 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4960 sizeof_field(struct siginfo, si_uid)) !=
4961 sizeof(void __user *));
4962 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4963 offsetof(struct siginfo, si_uid));
4964 }
4965#ifdef CONFIG_COMPAT
4966 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4967 offsetof(struct compat_siginfo, si_addr));
4968 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4969 sizeof(compat_uptr_t));
4970 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4971 sizeof_field(struct siginfo, si_pid));
4972#endif
4973}
4974
4975#if defined(CONFIG_SYSCTL)
4976static const struct ctl_table signal_debug_table[] = {
4977#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4978 {
4979 .procname = "exception-trace",
4980 .data = &show_unhandled_signals,
4981 .maxlen = sizeof(int),
4982 .mode = 0644,
4983 .proc_handler = proc_dointvec
4984 },
4985#endif
4986};
4987
4988static const struct ctl_table signal_table[] = {
4989 {
4990 .procname = "print-fatal-signals",
4991 .data = &print_fatal_signals,
4992 .maxlen = sizeof(int),
4993 .mode = 0644,
4994 .proc_handler = proc_dointvec,
4995 },
4996};
4997
4998static int __init init_signal_sysctls(void)
4999{
5000 register_sysctl_init("debug", signal_debug_table);
5001 register_sysctl_init("kernel", signal_table);
5002 return 0;
5003}
5004early_initcall(init_signal_sysctls);
5005#endif /* CONFIG_SYSCTL */
5006
5007void __init signals_init(void)
5008{
5009 siginfo_buildtime_checks();
5010
5011 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
5012}
5013
5014#ifdef CONFIG_KGDB_KDB
5015#include <linux/kdb.h>
5016/*
5017 * kdb_send_sig - Allows kdb to send signals without exposing
5018 * signal internals. This function checks if the required locks are
5019 * available before calling the main signal code, to avoid kdb
5020 * deadlocks.
5021 */
5022void kdb_send_sig(struct task_struct *t, int sig)
5023{
5024 static struct task_struct *kdb_prev_t;
5025 int new_t, ret;
5026 if (!spin_trylock(&t->sighand->siglock)) {
5027 kdb_printf("Can't do kill command now.\n"
5028 "The sigmask lock is held somewhere else in "
5029 "kernel, try again later\n");
5030 return;
5031 }
5032 new_t = kdb_prev_t != t;
5033 kdb_prev_t = t;
5034 if (!task_is_running(t) && new_t) {
5035 spin_unlock(&t->sighand->siglock);
5036 kdb_printf("Process is not RUNNING, sending a signal from "
5037 "kdb risks deadlock\n"
5038 "on the run queue locks. "
5039 "The signal has _not_ been sent.\n"
5040 "Reissue the kill command if you want to risk "
5041 "the deadlock.\n");
5042 return;
5043 }
5044 ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
5045 spin_unlock(&t->sighand->siglock);
5046 if (ret)
5047 kdb_printf("Fail to deliver Signal %d to process %d.\n",
5048 sig, t->pid);
5049 else
5050 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
5051}
5052#endif /* CONFIG_KGDB_KDB */
5053