Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
12 */
13
14#include <linux/slab.h>
15#include <linux/export.h>
16#include <linux/init.h>
17#include <linux/sched/mm.h>
18#include <linux/sched/user.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/sched/cputime.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/proc_fs.h>
26#include <linux/tty.h>
27#include <linux/binfmts.h>
28#include <linux/coredump.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/ptrace.h>
32#include <linux/signal.h>
33#include <linux/signalfd.h>
34#include <linux/ratelimit.h>
35#include <linux/tracehook.h>
36#include <linux/capability.h>
37#include <linux/freezer.h>
38#include <linux/pid_namespace.h>
39#include <linux/nsproxy.h>
40#include <linux/user_namespace.h>
41#include <linux/uprobes.h>
42#include <linux/compat.h>
43#include <linux/cn_proc.h>
44#include <linux/compiler.h>
45#include <linux/posix-timers.h>
46#include <linux/livepatch.h>
47#include <linux/cgroup.h>
48#include <linux/audit.h>
49
50#define CREATE_TRACE_POINTS
51#include <trace/events/signal.h>
52
53#include <asm/param.h>
54#include <linux/uaccess.h>
55#include <asm/unistd.h>
56#include <asm/siginfo.h>
57#include <asm/cacheflush.h>
58
59/*
60 * SLAB caches for signal bits.
61 */
62
63static struct kmem_cache *sigqueue_cachep;
64
65int print_fatal_signals __read_mostly;
66
67static void __user *sig_handler(struct task_struct *t, int sig)
68{
69 return t->sighand->action[sig - 1].sa.sa_handler;
70}
71
72static inline bool sig_handler_ignored(void __user *handler, int sig)
73{
74 /* Is it explicitly or implicitly ignored? */
75 return handler == SIG_IGN ||
76 (handler == SIG_DFL && sig_kernel_ignore(sig));
77}
78
79static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
80{
81 void __user *handler;
82
83 handler = sig_handler(t, sig);
84
85 /* SIGKILL and SIGSTOP may not be sent to the global init */
86 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
87 return true;
88
89 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
90 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
91 return true;
92
93 /* Only allow kernel generated signals to this kthread */
94 if (unlikely((t->flags & PF_KTHREAD) &&
95 (handler == SIG_KTHREAD_KERNEL) && !force))
96 return true;
97
98 return sig_handler_ignored(handler, sig);
99}
100
101static bool sig_ignored(struct task_struct *t, int sig, bool force)
102{
103 /*
104 * Blocked signals are never ignored, since the
105 * signal handler may change by the time it is
106 * unblocked.
107 */
108 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
109 return false;
110
111 /*
112 * Tracers may want to know about even ignored signal unless it
113 * is SIGKILL which can't be reported anyway but can be ignored
114 * by SIGNAL_UNKILLABLE task.
115 */
116 if (t->ptrace && sig != SIGKILL)
117 return false;
118
119 return sig_task_ignored(t, sig, force);
120}
121
122/*
123 * Re-calculate pending state from the set of locally pending
124 * signals, globally pending signals, and blocked signals.
125 */
126static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
127{
128 unsigned long ready;
129 long i;
130
131 switch (_NSIG_WORDS) {
132 default:
133 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
134 ready |= signal->sig[i] &~ blocked->sig[i];
135 break;
136
137 case 4: ready = signal->sig[3] &~ blocked->sig[3];
138 ready |= signal->sig[2] &~ blocked->sig[2];
139 ready |= signal->sig[1] &~ blocked->sig[1];
140 ready |= signal->sig[0] &~ blocked->sig[0];
141 break;
142
143 case 2: ready = signal->sig[1] &~ blocked->sig[1];
144 ready |= signal->sig[0] &~ blocked->sig[0];
145 break;
146
147 case 1: ready = signal->sig[0] &~ blocked->sig[0];
148 }
149 return ready != 0;
150}
151
152#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
153
154static bool recalc_sigpending_tsk(struct task_struct *t)
155{
156 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
157 PENDING(&t->pending, &t->blocked) ||
158 PENDING(&t->signal->shared_pending, &t->blocked) ||
159 cgroup_task_frozen(t)) {
160 set_tsk_thread_flag(t, TIF_SIGPENDING);
161 return true;
162 }
163
164 /*
165 * We must never clear the flag in another thread, or in current
166 * when it's possible the current syscall is returning -ERESTART*.
167 * So we don't clear it here, and only callers who know they should do.
168 */
169 return false;
170}
171
172/*
173 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
174 * This is superfluous when called on current, the wakeup is a harmless no-op.
175 */
176void recalc_sigpending_and_wake(struct task_struct *t)
177{
178 if (recalc_sigpending_tsk(t))
179 signal_wake_up(t, 0);
180}
181
182void recalc_sigpending(void)
183{
184 if (!recalc_sigpending_tsk(current) && !freezing(current) &&
185 !klp_patch_pending(current))
186 clear_thread_flag(TIF_SIGPENDING);
187
188}
189EXPORT_SYMBOL(recalc_sigpending);
190
191void calculate_sigpending(void)
192{
193 /* Have any signals or users of TIF_SIGPENDING been delayed
194 * until after fork?
195 */
196 spin_lock_irq(¤t->sighand->siglock);
197 set_tsk_thread_flag(current, TIF_SIGPENDING);
198 recalc_sigpending();
199 spin_unlock_irq(¤t->sighand->siglock);
200}
201
202/* Given the mask, find the first available signal that should be serviced. */
203
204#define SYNCHRONOUS_MASK \
205 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
206 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
207
208int next_signal(struct sigpending *pending, sigset_t *mask)
209{
210 unsigned long i, *s, *m, x;
211 int sig = 0;
212
213 s = pending->signal.sig;
214 m = mask->sig;
215
216 /*
217 * Handle the first word specially: it contains the
218 * synchronous signals that need to be dequeued first.
219 */
220 x = *s &~ *m;
221 if (x) {
222 if (x & SYNCHRONOUS_MASK)
223 x &= SYNCHRONOUS_MASK;
224 sig = ffz(~x) + 1;
225 return sig;
226 }
227
228 switch (_NSIG_WORDS) {
229 default:
230 for (i = 1; i < _NSIG_WORDS; ++i) {
231 x = *++s &~ *++m;
232 if (!x)
233 continue;
234 sig = ffz(~x) + i*_NSIG_BPW + 1;
235 break;
236 }
237 break;
238
239 case 2:
240 x = s[1] &~ m[1];
241 if (!x)
242 break;
243 sig = ffz(~x) + _NSIG_BPW + 1;
244 break;
245
246 case 1:
247 /* Nothing to do */
248 break;
249 }
250
251 return sig;
252}
253
254static inline void print_dropped_signal(int sig)
255{
256 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
257
258 if (!print_fatal_signals)
259 return;
260
261 if (!__ratelimit(&ratelimit_state))
262 return;
263
264 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
265 current->comm, current->pid, sig);
266}
267
268/**
269 * task_set_jobctl_pending - set jobctl pending bits
270 * @task: target task
271 * @mask: pending bits to set
272 *
273 * Clear @mask from @task->jobctl. @mask must be subset of
274 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
275 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
276 * cleared. If @task is already being killed or exiting, this function
277 * becomes noop.
278 *
279 * CONTEXT:
280 * Must be called with @task->sighand->siglock held.
281 *
282 * RETURNS:
283 * %true if @mask is set, %false if made noop because @task was dying.
284 */
285bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
286{
287 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
288 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
289 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
290
291 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
292 return false;
293
294 if (mask & JOBCTL_STOP_SIGMASK)
295 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
296
297 task->jobctl |= mask;
298 return true;
299}
300
301/**
302 * task_clear_jobctl_trapping - clear jobctl trapping bit
303 * @task: target task
304 *
305 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
306 * Clear it and wake up the ptracer. Note that we don't need any further
307 * locking. @task->siglock guarantees that @task->parent points to the
308 * ptracer.
309 *
310 * CONTEXT:
311 * Must be called with @task->sighand->siglock held.
312 */
313void task_clear_jobctl_trapping(struct task_struct *task)
314{
315 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
316 task->jobctl &= ~JOBCTL_TRAPPING;
317 smp_mb(); /* advised by wake_up_bit() */
318 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
319 }
320}
321
322/**
323 * task_clear_jobctl_pending - clear jobctl pending bits
324 * @task: target task
325 * @mask: pending bits to clear
326 *
327 * Clear @mask from @task->jobctl. @mask must be subset of
328 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
329 * STOP bits are cleared together.
330 *
331 * If clearing of @mask leaves no stop or trap pending, this function calls
332 * task_clear_jobctl_trapping().
333 *
334 * CONTEXT:
335 * Must be called with @task->sighand->siglock held.
336 */
337void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
338{
339 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
340
341 if (mask & JOBCTL_STOP_PENDING)
342 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
343
344 task->jobctl &= ~mask;
345
346 if (!(task->jobctl & JOBCTL_PENDING_MASK))
347 task_clear_jobctl_trapping(task);
348}
349
350/**
351 * task_participate_group_stop - participate in a group stop
352 * @task: task participating in a group stop
353 *
354 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
355 * Group stop states are cleared and the group stop count is consumed if
356 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
357 * stop, the appropriate `SIGNAL_*` flags are set.
358 *
359 * CONTEXT:
360 * Must be called with @task->sighand->siglock held.
361 *
362 * RETURNS:
363 * %true if group stop completion should be notified to the parent, %false
364 * otherwise.
365 */
366static bool task_participate_group_stop(struct task_struct *task)
367{
368 struct signal_struct *sig = task->signal;
369 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
370
371 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
372
373 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
374
375 if (!consume)
376 return false;
377
378 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
379 sig->group_stop_count--;
380
381 /*
382 * Tell the caller to notify completion iff we are entering into a
383 * fresh group stop. Read comment in do_signal_stop() for details.
384 */
385 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
386 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
387 return true;
388 }
389 return false;
390}
391
392void task_join_group_stop(struct task_struct *task)
393{
394 /* Have the new thread join an on-going signal group stop */
395 unsigned long jobctl = current->jobctl;
396 if (jobctl & JOBCTL_STOP_PENDING) {
397 struct signal_struct *sig = current->signal;
398 unsigned long signr = jobctl & JOBCTL_STOP_SIGMASK;
399 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
400 if (task_set_jobctl_pending(task, signr | gstop)) {
401 sig->group_stop_count++;
402 }
403 }
404}
405
406/*
407 * allocate a new signal queue record
408 * - this may be called without locks if and only if t == current, otherwise an
409 * appropriate lock must be held to stop the target task from exiting
410 */
411static struct sigqueue *
412__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
413{
414 struct sigqueue *q = NULL;
415 struct user_struct *user;
416
417 /*
418 * Protect access to @t credentials. This can go away when all
419 * callers hold rcu read lock.
420 */
421 rcu_read_lock();
422 user = get_uid(__task_cred(t)->user);
423 atomic_inc(&user->sigpending);
424 rcu_read_unlock();
425
426 if (override_rlimit ||
427 atomic_read(&user->sigpending) <=
428 task_rlimit(t, RLIMIT_SIGPENDING)) {
429 q = kmem_cache_alloc(sigqueue_cachep, flags);
430 } else {
431 print_dropped_signal(sig);
432 }
433
434 if (unlikely(q == NULL)) {
435 atomic_dec(&user->sigpending);
436 free_uid(user);
437 } else {
438 INIT_LIST_HEAD(&q->list);
439 q->flags = 0;
440 q->user = user;
441 }
442
443 return q;
444}
445
446static void __sigqueue_free(struct sigqueue *q)
447{
448 if (q->flags & SIGQUEUE_PREALLOC)
449 return;
450 atomic_dec(&q->user->sigpending);
451 free_uid(q->user);
452 kmem_cache_free(sigqueue_cachep, q);
453}
454
455void flush_sigqueue(struct sigpending *queue)
456{
457 struct sigqueue *q;
458
459 sigemptyset(&queue->signal);
460 while (!list_empty(&queue->list)) {
461 q = list_entry(queue->list.next, struct sigqueue , list);
462 list_del_init(&q->list);
463 __sigqueue_free(q);
464 }
465}
466
467/*
468 * Flush all pending signals for this kthread.
469 */
470void flush_signals(struct task_struct *t)
471{
472 unsigned long flags;
473
474 spin_lock_irqsave(&t->sighand->siglock, flags);
475 clear_tsk_thread_flag(t, TIF_SIGPENDING);
476 flush_sigqueue(&t->pending);
477 flush_sigqueue(&t->signal->shared_pending);
478 spin_unlock_irqrestore(&t->sighand->siglock, flags);
479}
480EXPORT_SYMBOL(flush_signals);
481
482#ifdef CONFIG_POSIX_TIMERS
483static void __flush_itimer_signals(struct sigpending *pending)
484{
485 sigset_t signal, retain;
486 struct sigqueue *q, *n;
487
488 signal = pending->signal;
489 sigemptyset(&retain);
490
491 list_for_each_entry_safe(q, n, &pending->list, list) {
492 int sig = q->info.si_signo;
493
494 if (likely(q->info.si_code != SI_TIMER)) {
495 sigaddset(&retain, sig);
496 } else {
497 sigdelset(&signal, sig);
498 list_del_init(&q->list);
499 __sigqueue_free(q);
500 }
501 }
502
503 sigorsets(&pending->signal, &signal, &retain);
504}
505
506void flush_itimer_signals(void)
507{
508 struct task_struct *tsk = current;
509 unsigned long flags;
510
511 spin_lock_irqsave(&tsk->sighand->siglock, flags);
512 __flush_itimer_signals(&tsk->pending);
513 __flush_itimer_signals(&tsk->signal->shared_pending);
514 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
515}
516#endif
517
518void ignore_signals(struct task_struct *t)
519{
520 int i;
521
522 for (i = 0; i < _NSIG; ++i)
523 t->sighand->action[i].sa.sa_handler = SIG_IGN;
524
525 flush_signals(t);
526}
527
528/*
529 * Flush all handlers for a task.
530 */
531
532void
533flush_signal_handlers(struct task_struct *t, int force_default)
534{
535 int i;
536 struct k_sigaction *ka = &t->sighand->action[0];
537 for (i = _NSIG ; i != 0 ; i--) {
538 if (force_default || ka->sa.sa_handler != SIG_IGN)
539 ka->sa.sa_handler = SIG_DFL;
540 ka->sa.sa_flags = 0;
541#ifdef __ARCH_HAS_SA_RESTORER
542 ka->sa.sa_restorer = NULL;
543#endif
544 sigemptyset(&ka->sa.sa_mask);
545 ka++;
546 }
547}
548
549bool unhandled_signal(struct task_struct *tsk, int sig)
550{
551 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
552 if (is_global_init(tsk))
553 return true;
554
555 if (handler != SIG_IGN && handler != SIG_DFL)
556 return false;
557
558 /* if ptraced, let the tracer determine */
559 return !tsk->ptrace;
560}
561
562static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
563 bool *resched_timer)
564{
565 struct sigqueue *q, *first = NULL;
566
567 /*
568 * Collect the siginfo appropriate to this signal. Check if
569 * there is another siginfo for the same signal.
570 */
571 list_for_each_entry(q, &list->list, list) {
572 if (q->info.si_signo == sig) {
573 if (first)
574 goto still_pending;
575 first = q;
576 }
577 }
578
579 sigdelset(&list->signal, sig);
580
581 if (first) {
582still_pending:
583 list_del_init(&first->list);
584 copy_siginfo(info, &first->info);
585
586 *resched_timer =
587 (first->flags & SIGQUEUE_PREALLOC) &&
588 (info->si_code == SI_TIMER) &&
589 (info->si_sys_private);
590
591 __sigqueue_free(first);
592 } else {
593 /*
594 * Ok, it wasn't in the queue. This must be
595 * a fast-pathed signal or we must have been
596 * out of queue space. So zero out the info.
597 */
598 clear_siginfo(info);
599 info->si_signo = sig;
600 info->si_errno = 0;
601 info->si_code = SI_USER;
602 info->si_pid = 0;
603 info->si_uid = 0;
604 }
605}
606
607static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
608 kernel_siginfo_t *info, bool *resched_timer)
609{
610 int sig = next_signal(pending, mask);
611
612 if (sig)
613 collect_signal(sig, pending, info, resched_timer);
614 return sig;
615}
616
617/*
618 * Dequeue a signal and return the element to the caller, which is
619 * expected to free it.
620 *
621 * All callers have to hold the siglock.
622 */
623int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
624{
625 bool resched_timer = false;
626 int signr;
627
628 /* We only dequeue private signals from ourselves, we don't let
629 * signalfd steal them
630 */
631 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
632 if (!signr) {
633 signr = __dequeue_signal(&tsk->signal->shared_pending,
634 mask, info, &resched_timer);
635#ifdef CONFIG_POSIX_TIMERS
636 /*
637 * itimer signal ?
638 *
639 * itimers are process shared and we restart periodic
640 * itimers in the signal delivery path to prevent DoS
641 * attacks in the high resolution timer case. This is
642 * compliant with the old way of self-restarting
643 * itimers, as the SIGALRM is a legacy signal and only
644 * queued once. Changing the restart behaviour to
645 * restart the timer in the signal dequeue path is
646 * reducing the timer noise on heavy loaded !highres
647 * systems too.
648 */
649 if (unlikely(signr == SIGALRM)) {
650 struct hrtimer *tmr = &tsk->signal->real_timer;
651
652 if (!hrtimer_is_queued(tmr) &&
653 tsk->signal->it_real_incr != 0) {
654 hrtimer_forward(tmr, tmr->base->get_time(),
655 tsk->signal->it_real_incr);
656 hrtimer_restart(tmr);
657 }
658 }
659#endif
660 }
661
662 recalc_sigpending();
663 if (!signr)
664 return 0;
665
666 if (unlikely(sig_kernel_stop(signr))) {
667 /*
668 * Set a marker that we have dequeued a stop signal. Our
669 * caller might release the siglock and then the pending
670 * stop signal it is about to process is no longer in the
671 * pending bitmasks, but must still be cleared by a SIGCONT
672 * (and overruled by a SIGKILL). So those cases clear this
673 * shared flag after we've set it. Note that this flag may
674 * remain set after the signal we return is ignored or
675 * handled. That doesn't matter because its only purpose
676 * is to alert stop-signal processing code when another
677 * processor has come along and cleared the flag.
678 */
679 current->jobctl |= JOBCTL_STOP_DEQUEUED;
680 }
681#ifdef CONFIG_POSIX_TIMERS
682 if (resched_timer) {
683 /*
684 * Release the siglock to ensure proper locking order
685 * of timer locks outside of siglocks. Note, we leave
686 * irqs disabled here, since the posix-timers code is
687 * about to disable them again anyway.
688 */
689 spin_unlock(&tsk->sighand->siglock);
690 posixtimer_rearm(info);
691 spin_lock(&tsk->sighand->siglock);
692
693 /* Don't expose the si_sys_private value to userspace */
694 info->si_sys_private = 0;
695 }
696#endif
697 return signr;
698}
699EXPORT_SYMBOL_GPL(dequeue_signal);
700
701static int dequeue_synchronous_signal(kernel_siginfo_t *info)
702{
703 struct task_struct *tsk = current;
704 struct sigpending *pending = &tsk->pending;
705 struct sigqueue *q, *sync = NULL;
706
707 /*
708 * Might a synchronous signal be in the queue?
709 */
710 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
711 return 0;
712
713 /*
714 * Return the first synchronous signal in the queue.
715 */
716 list_for_each_entry(q, &pending->list, list) {
717 /* Synchronous signals have a postive si_code */
718 if ((q->info.si_code > SI_USER) &&
719 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
720 sync = q;
721 goto next;
722 }
723 }
724 return 0;
725next:
726 /*
727 * Check if there is another siginfo for the same signal.
728 */
729 list_for_each_entry_continue(q, &pending->list, list) {
730 if (q->info.si_signo == sync->info.si_signo)
731 goto still_pending;
732 }
733
734 sigdelset(&pending->signal, sync->info.si_signo);
735 recalc_sigpending();
736still_pending:
737 list_del_init(&sync->list);
738 copy_siginfo(info, &sync->info);
739 __sigqueue_free(sync);
740 return info->si_signo;
741}
742
743/*
744 * Tell a process that it has a new active signal..
745 *
746 * NOTE! we rely on the previous spin_lock to
747 * lock interrupts for us! We can only be called with
748 * "siglock" held, and the local interrupt must
749 * have been disabled when that got acquired!
750 *
751 * No need to set need_resched since signal event passing
752 * goes through ->blocked
753 */
754void signal_wake_up_state(struct task_struct *t, unsigned int state)
755{
756 set_tsk_thread_flag(t, TIF_SIGPENDING);
757 /*
758 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
759 * case. We don't check t->state here because there is a race with it
760 * executing another processor and just now entering stopped state.
761 * By using wake_up_state, we ensure the process will wake up and
762 * handle its death signal.
763 */
764 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
765 kick_process(t);
766}
767
768/*
769 * Remove signals in mask from the pending set and queue.
770 * Returns 1 if any signals were found.
771 *
772 * All callers must be holding the siglock.
773 */
774static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
775{
776 struct sigqueue *q, *n;
777 sigset_t m;
778
779 sigandsets(&m, mask, &s->signal);
780 if (sigisemptyset(&m))
781 return;
782
783 sigandnsets(&s->signal, &s->signal, mask);
784 list_for_each_entry_safe(q, n, &s->list, list) {
785 if (sigismember(mask, q->info.si_signo)) {
786 list_del_init(&q->list);
787 __sigqueue_free(q);
788 }
789 }
790}
791
792static inline int is_si_special(const struct kernel_siginfo *info)
793{
794 return info <= SEND_SIG_PRIV;
795}
796
797static inline bool si_fromuser(const struct kernel_siginfo *info)
798{
799 return info == SEND_SIG_NOINFO ||
800 (!is_si_special(info) && SI_FROMUSER(info));
801}
802
803/*
804 * called with RCU read lock from check_kill_permission()
805 */
806static bool kill_ok_by_cred(struct task_struct *t)
807{
808 const struct cred *cred = current_cred();
809 const struct cred *tcred = __task_cred(t);
810
811 return uid_eq(cred->euid, tcred->suid) ||
812 uid_eq(cred->euid, tcred->uid) ||
813 uid_eq(cred->uid, tcred->suid) ||
814 uid_eq(cred->uid, tcred->uid) ||
815 ns_capable(tcred->user_ns, CAP_KILL);
816}
817
818/*
819 * Bad permissions for sending the signal
820 * - the caller must hold the RCU read lock
821 */
822static int check_kill_permission(int sig, struct kernel_siginfo *info,
823 struct task_struct *t)
824{
825 struct pid *sid;
826 int error;
827
828 if (!valid_signal(sig))
829 return -EINVAL;
830
831 if (!si_fromuser(info))
832 return 0;
833
834 error = audit_signal_info(sig, t); /* Let audit system see the signal */
835 if (error)
836 return error;
837
838 if (!same_thread_group(current, t) &&
839 !kill_ok_by_cred(t)) {
840 switch (sig) {
841 case SIGCONT:
842 sid = task_session(t);
843 /*
844 * We don't return the error if sid == NULL. The
845 * task was unhashed, the caller must notice this.
846 */
847 if (!sid || sid == task_session(current))
848 break;
849 /* fall through */
850 default:
851 return -EPERM;
852 }
853 }
854
855 return security_task_kill(t, info, sig, NULL);
856}
857
858/**
859 * ptrace_trap_notify - schedule trap to notify ptracer
860 * @t: tracee wanting to notify tracer
861 *
862 * This function schedules sticky ptrace trap which is cleared on the next
863 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
864 * ptracer.
865 *
866 * If @t is running, STOP trap will be taken. If trapped for STOP and
867 * ptracer is listening for events, tracee is woken up so that it can
868 * re-trap for the new event. If trapped otherwise, STOP trap will be
869 * eventually taken without returning to userland after the existing traps
870 * are finished by PTRACE_CONT.
871 *
872 * CONTEXT:
873 * Must be called with @task->sighand->siglock held.
874 */
875static void ptrace_trap_notify(struct task_struct *t)
876{
877 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
878 assert_spin_locked(&t->sighand->siglock);
879
880 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
881 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
882}
883
884/*
885 * Handle magic process-wide effects of stop/continue signals. Unlike
886 * the signal actions, these happen immediately at signal-generation
887 * time regardless of blocking, ignoring, or handling. This does the
888 * actual continuing for SIGCONT, but not the actual stopping for stop
889 * signals. The process stop is done as a signal action for SIG_DFL.
890 *
891 * Returns true if the signal should be actually delivered, otherwise
892 * it should be dropped.
893 */
894static bool prepare_signal(int sig, struct task_struct *p, bool force)
895{
896 struct signal_struct *signal = p->signal;
897 struct task_struct *t;
898 sigset_t flush;
899
900 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
901 if (!(signal->flags & SIGNAL_GROUP_EXIT))
902 return sig == SIGKILL;
903 /*
904 * The process is in the middle of dying, nothing to do.
905 */
906 } else if (sig_kernel_stop(sig)) {
907 /*
908 * This is a stop signal. Remove SIGCONT from all queues.
909 */
910 siginitset(&flush, sigmask(SIGCONT));
911 flush_sigqueue_mask(&flush, &signal->shared_pending);
912 for_each_thread(p, t)
913 flush_sigqueue_mask(&flush, &t->pending);
914 } else if (sig == SIGCONT) {
915 unsigned int why;
916 /*
917 * Remove all stop signals from all queues, wake all threads.
918 */
919 siginitset(&flush, SIG_KERNEL_STOP_MASK);
920 flush_sigqueue_mask(&flush, &signal->shared_pending);
921 for_each_thread(p, t) {
922 flush_sigqueue_mask(&flush, &t->pending);
923 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
924 if (likely(!(t->ptrace & PT_SEIZED)))
925 wake_up_state(t, __TASK_STOPPED);
926 else
927 ptrace_trap_notify(t);
928 }
929
930 /*
931 * Notify the parent with CLD_CONTINUED if we were stopped.
932 *
933 * If we were in the middle of a group stop, we pretend it
934 * was already finished, and then continued. Since SIGCHLD
935 * doesn't queue we report only CLD_STOPPED, as if the next
936 * CLD_CONTINUED was dropped.
937 */
938 why = 0;
939 if (signal->flags & SIGNAL_STOP_STOPPED)
940 why |= SIGNAL_CLD_CONTINUED;
941 else if (signal->group_stop_count)
942 why |= SIGNAL_CLD_STOPPED;
943
944 if (why) {
945 /*
946 * The first thread which returns from do_signal_stop()
947 * will take ->siglock, notice SIGNAL_CLD_MASK, and
948 * notify its parent. See get_signal().
949 */
950 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
951 signal->group_stop_count = 0;
952 signal->group_exit_code = 0;
953 }
954 }
955
956 return !sig_ignored(p, sig, force);
957}
958
959/*
960 * Test if P wants to take SIG. After we've checked all threads with this,
961 * it's equivalent to finding no threads not blocking SIG. Any threads not
962 * blocking SIG were ruled out because they are not running and already
963 * have pending signals. Such threads will dequeue from the shared queue
964 * as soon as they're available, so putting the signal on the shared queue
965 * will be equivalent to sending it to one such thread.
966 */
967static inline bool wants_signal(int sig, struct task_struct *p)
968{
969 if (sigismember(&p->blocked, sig))
970 return false;
971
972 if (p->flags & PF_EXITING)
973 return false;
974
975 if (sig == SIGKILL)
976 return true;
977
978 if (task_is_stopped_or_traced(p))
979 return false;
980
981 return task_curr(p) || !signal_pending(p);
982}
983
984static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
985{
986 struct signal_struct *signal = p->signal;
987 struct task_struct *t;
988
989 /*
990 * Now find a thread we can wake up to take the signal off the queue.
991 *
992 * If the main thread wants the signal, it gets first crack.
993 * Probably the least surprising to the average bear.
994 */
995 if (wants_signal(sig, p))
996 t = p;
997 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
998 /*
999 * There is just one thread and it does not need to be woken.
1000 * It will dequeue unblocked signals before it runs again.
1001 */
1002 return;
1003 else {
1004 /*
1005 * Otherwise try to find a suitable thread.
1006 */
1007 t = signal->curr_target;
1008 while (!wants_signal(sig, t)) {
1009 t = next_thread(t);
1010 if (t == signal->curr_target)
1011 /*
1012 * No thread needs to be woken.
1013 * Any eligible threads will see
1014 * the signal in the queue soon.
1015 */
1016 return;
1017 }
1018 signal->curr_target = t;
1019 }
1020
1021 /*
1022 * Found a killable thread. If the signal will be fatal,
1023 * then start taking the whole group down immediately.
1024 */
1025 if (sig_fatal(p, sig) &&
1026 !(signal->flags & SIGNAL_GROUP_EXIT) &&
1027 !sigismember(&t->real_blocked, sig) &&
1028 (sig == SIGKILL || !p->ptrace)) {
1029 /*
1030 * This signal will be fatal to the whole group.
1031 */
1032 if (!sig_kernel_coredump(sig)) {
1033 /*
1034 * Start a group exit and wake everybody up.
1035 * This way we don't have other threads
1036 * running and doing things after a slower
1037 * thread has the fatal signal pending.
1038 */
1039 signal->flags = SIGNAL_GROUP_EXIT;
1040 signal->group_exit_code = sig;
1041 signal->group_stop_count = 0;
1042 t = p;
1043 do {
1044 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1045 sigaddset(&t->pending.signal, SIGKILL);
1046 signal_wake_up(t, 1);
1047 } while_each_thread(p, t);
1048 return;
1049 }
1050 }
1051
1052 /*
1053 * The signal is already in the shared-pending queue.
1054 * Tell the chosen thread to wake up and dequeue it.
1055 */
1056 signal_wake_up(t, sig == SIGKILL);
1057 return;
1058}
1059
1060static inline bool legacy_queue(struct sigpending *signals, int sig)
1061{
1062 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1063}
1064
1065static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1066 enum pid_type type, bool force)
1067{
1068 struct sigpending *pending;
1069 struct sigqueue *q;
1070 int override_rlimit;
1071 int ret = 0, result;
1072
1073 assert_spin_locked(&t->sighand->siglock);
1074
1075 result = TRACE_SIGNAL_IGNORED;
1076 if (!prepare_signal(sig, t, force))
1077 goto ret;
1078
1079 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1080 /*
1081 * Short-circuit ignored signals and support queuing
1082 * exactly one non-rt signal, so that we can get more
1083 * detailed information about the cause of the signal.
1084 */
1085 result = TRACE_SIGNAL_ALREADY_PENDING;
1086 if (legacy_queue(pending, sig))
1087 goto ret;
1088
1089 result = TRACE_SIGNAL_DELIVERED;
1090 /*
1091 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1092 */
1093 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1094 goto out_set;
1095
1096 /*
1097 * Real-time signals must be queued if sent by sigqueue, or
1098 * some other real-time mechanism. It is implementation
1099 * defined whether kill() does so. We attempt to do so, on
1100 * the principle of least surprise, but since kill is not
1101 * allowed to fail with EAGAIN when low on memory we just
1102 * make sure at least one signal gets delivered and don't
1103 * pass on the info struct.
1104 */
1105 if (sig < SIGRTMIN)
1106 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1107 else
1108 override_rlimit = 0;
1109
1110 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1111 if (q) {
1112 list_add_tail(&q->list, &pending->list);
1113 switch ((unsigned long) info) {
1114 case (unsigned long) SEND_SIG_NOINFO:
1115 clear_siginfo(&q->info);
1116 q->info.si_signo = sig;
1117 q->info.si_errno = 0;
1118 q->info.si_code = SI_USER;
1119 q->info.si_pid = task_tgid_nr_ns(current,
1120 task_active_pid_ns(t));
1121 rcu_read_lock();
1122 q->info.si_uid =
1123 from_kuid_munged(task_cred_xxx(t, user_ns),
1124 current_uid());
1125 rcu_read_unlock();
1126 break;
1127 case (unsigned long) SEND_SIG_PRIV:
1128 clear_siginfo(&q->info);
1129 q->info.si_signo = sig;
1130 q->info.si_errno = 0;
1131 q->info.si_code = SI_KERNEL;
1132 q->info.si_pid = 0;
1133 q->info.si_uid = 0;
1134 break;
1135 default:
1136 copy_siginfo(&q->info, info);
1137 break;
1138 }
1139 } else if (!is_si_special(info) &&
1140 sig >= SIGRTMIN && info->si_code != SI_USER) {
1141 /*
1142 * Queue overflow, abort. We may abort if the
1143 * signal was rt and sent by user using something
1144 * other than kill().
1145 */
1146 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1147 ret = -EAGAIN;
1148 goto ret;
1149 } else {
1150 /*
1151 * This is a silent loss of information. We still
1152 * send the signal, but the *info bits are lost.
1153 */
1154 result = TRACE_SIGNAL_LOSE_INFO;
1155 }
1156
1157out_set:
1158 signalfd_notify(t, sig);
1159 sigaddset(&pending->signal, sig);
1160
1161 /* Let multiprocess signals appear after on-going forks */
1162 if (type > PIDTYPE_TGID) {
1163 struct multiprocess_signals *delayed;
1164 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1165 sigset_t *signal = &delayed->signal;
1166 /* Can't queue both a stop and a continue signal */
1167 if (sig == SIGCONT)
1168 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1169 else if (sig_kernel_stop(sig))
1170 sigdelset(signal, SIGCONT);
1171 sigaddset(signal, sig);
1172 }
1173 }
1174
1175 complete_signal(sig, t, type);
1176ret:
1177 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1178 return ret;
1179}
1180
1181static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1182{
1183 bool ret = false;
1184 switch (siginfo_layout(info->si_signo, info->si_code)) {
1185 case SIL_KILL:
1186 case SIL_CHLD:
1187 case SIL_RT:
1188 ret = true;
1189 break;
1190 case SIL_TIMER:
1191 case SIL_POLL:
1192 case SIL_FAULT:
1193 case SIL_FAULT_MCEERR:
1194 case SIL_FAULT_BNDERR:
1195 case SIL_FAULT_PKUERR:
1196 case SIL_SYS:
1197 ret = false;
1198 break;
1199 }
1200 return ret;
1201}
1202
1203static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1204 enum pid_type type)
1205{
1206 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1207 bool force = false;
1208
1209 if (info == SEND_SIG_NOINFO) {
1210 /* Force if sent from an ancestor pid namespace */
1211 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1212 } else if (info == SEND_SIG_PRIV) {
1213 /* Don't ignore kernel generated signals */
1214 force = true;
1215 } else if (has_si_pid_and_uid(info)) {
1216 /* SIGKILL and SIGSTOP is special or has ids */
1217 struct user_namespace *t_user_ns;
1218
1219 rcu_read_lock();
1220 t_user_ns = task_cred_xxx(t, user_ns);
1221 if (current_user_ns() != t_user_ns) {
1222 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1223 info->si_uid = from_kuid_munged(t_user_ns, uid);
1224 }
1225 rcu_read_unlock();
1226
1227 /* A kernel generated signal? */
1228 force = (info->si_code == SI_KERNEL);
1229
1230 /* From an ancestor pid namespace? */
1231 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1232 info->si_pid = 0;
1233 force = true;
1234 }
1235 }
1236 return __send_signal(sig, info, t, type, force);
1237}
1238
1239static void print_fatal_signal(int signr)
1240{
1241 struct pt_regs *regs = signal_pt_regs();
1242 pr_info("potentially unexpected fatal signal %d.\n", signr);
1243
1244#if defined(__i386__) && !defined(__arch_um__)
1245 pr_info("code at %08lx: ", regs->ip);
1246 {
1247 int i;
1248 for (i = 0; i < 16; i++) {
1249 unsigned char insn;
1250
1251 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1252 break;
1253 pr_cont("%02x ", insn);
1254 }
1255 }
1256 pr_cont("\n");
1257#endif
1258 preempt_disable();
1259 show_regs(regs);
1260 preempt_enable();
1261}
1262
1263static int __init setup_print_fatal_signals(char *str)
1264{
1265 get_option (&str, &print_fatal_signals);
1266
1267 return 1;
1268}
1269
1270__setup("print-fatal-signals=", setup_print_fatal_signals);
1271
1272int
1273__group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1274{
1275 return send_signal(sig, info, p, PIDTYPE_TGID);
1276}
1277
1278int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1279 enum pid_type type)
1280{
1281 unsigned long flags;
1282 int ret = -ESRCH;
1283
1284 if (lock_task_sighand(p, &flags)) {
1285 ret = send_signal(sig, info, p, type);
1286 unlock_task_sighand(p, &flags);
1287 }
1288
1289 return ret;
1290}
1291
1292/*
1293 * Force a signal that the process can't ignore: if necessary
1294 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1295 *
1296 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1297 * since we do not want to have a signal handler that was blocked
1298 * be invoked when user space had explicitly blocked it.
1299 *
1300 * We don't want to have recursive SIGSEGV's etc, for example,
1301 * that is why we also clear SIGNAL_UNKILLABLE.
1302 */
1303static int
1304force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
1305{
1306 unsigned long int flags;
1307 int ret, blocked, ignored;
1308 struct k_sigaction *action;
1309 int sig = info->si_signo;
1310
1311 spin_lock_irqsave(&t->sighand->siglock, flags);
1312 action = &t->sighand->action[sig-1];
1313 ignored = action->sa.sa_handler == SIG_IGN;
1314 blocked = sigismember(&t->blocked, sig);
1315 if (blocked || ignored) {
1316 action->sa.sa_handler = SIG_DFL;
1317 if (blocked) {
1318 sigdelset(&t->blocked, sig);
1319 recalc_sigpending_and_wake(t);
1320 }
1321 }
1322 /*
1323 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1324 * debugging to leave init killable.
1325 */
1326 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1327 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1328 ret = send_signal(sig, info, t, PIDTYPE_PID);
1329 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1330
1331 return ret;
1332}
1333
1334int force_sig_info(struct kernel_siginfo *info)
1335{
1336 return force_sig_info_to_task(info, current);
1337}
1338
1339/*
1340 * Nuke all other threads in the group.
1341 */
1342int zap_other_threads(struct task_struct *p)
1343{
1344 struct task_struct *t = p;
1345 int count = 0;
1346
1347 p->signal->group_stop_count = 0;
1348
1349 while_each_thread(p, t) {
1350 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1351 count++;
1352
1353 /* Don't bother with already dead threads */
1354 if (t->exit_state)
1355 continue;
1356 sigaddset(&t->pending.signal, SIGKILL);
1357 signal_wake_up(t, 1);
1358 }
1359
1360 return count;
1361}
1362
1363struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1364 unsigned long *flags)
1365{
1366 struct sighand_struct *sighand;
1367
1368 rcu_read_lock();
1369 for (;;) {
1370 sighand = rcu_dereference(tsk->sighand);
1371 if (unlikely(sighand == NULL))
1372 break;
1373
1374 /*
1375 * This sighand can be already freed and even reused, but
1376 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1377 * initializes ->siglock: this slab can't go away, it has
1378 * the same object type, ->siglock can't be reinitialized.
1379 *
1380 * We need to ensure that tsk->sighand is still the same
1381 * after we take the lock, we can race with de_thread() or
1382 * __exit_signal(). In the latter case the next iteration
1383 * must see ->sighand == NULL.
1384 */
1385 spin_lock_irqsave(&sighand->siglock, *flags);
1386 if (likely(sighand == tsk->sighand))
1387 break;
1388 spin_unlock_irqrestore(&sighand->siglock, *flags);
1389 }
1390 rcu_read_unlock();
1391
1392 return sighand;
1393}
1394
1395/*
1396 * send signal info to all the members of a group
1397 */
1398int group_send_sig_info(int sig, struct kernel_siginfo *info,
1399 struct task_struct *p, enum pid_type type)
1400{
1401 int ret;
1402
1403 rcu_read_lock();
1404 ret = check_kill_permission(sig, info, p);
1405 rcu_read_unlock();
1406
1407 if (!ret && sig)
1408 ret = do_send_sig_info(sig, info, p, type);
1409
1410 return ret;
1411}
1412
1413/*
1414 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1415 * control characters do (^C, ^Z etc)
1416 * - the caller must hold at least a readlock on tasklist_lock
1417 */
1418int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1419{
1420 struct task_struct *p = NULL;
1421 int retval, success;
1422
1423 success = 0;
1424 retval = -ESRCH;
1425 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1426 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1427 success |= !err;
1428 retval = err;
1429 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1430 return success ? 0 : retval;
1431}
1432
1433int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1434{
1435 int error = -ESRCH;
1436 struct task_struct *p;
1437
1438 for (;;) {
1439 rcu_read_lock();
1440 p = pid_task(pid, PIDTYPE_PID);
1441 if (p)
1442 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1443 rcu_read_unlock();
1444 if (likely(!p || error != -ESRCH))
1445 return error;
1446
1447 /*
1448 * The task was unhashed in between, try again. If it
1449 * is dead, pid_task() will return NULL, if we race with
1450 * de_thread() it will find the new leader.
1451 */
1452 }
1453}
1454
1455static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1456{
1457 int error;
1458 rcu_read_lock();
1459 error = kill_pid_info(sig, info, find_vpid(pid));
1460 rcu_read_unlock();
1461 return error;
1462}
1463
1464static inline bool kill_as_cred_perm(const struct cred *cred,
1465 struct task_struct *target)
1466{
1467 const struct cred *pcred = __task_cred(target);
1468
1469 return uid_eq(cred->euid, pcred->suid) ||
1470 uid_eq(cred->euid, pcred->uid) ||
1471 uid_eq(cred->uid, pcred->suid) ||
1472 uid_eq(cred->uid, pcred->uid);
1473}
1474
1475/*
1476 * The usb asyncio usage of siginfo is wrong. The glibc support
1477 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1478 * AKA after the generic fields:
1479 * kernel_pid_t si_pid;
1480 * kernel_uid32_t si_uid;
1481 * sigval_t si_value;
1482 *
1483 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1484 * after the generic fields is:
1485 * void __user *si_addr;
1486 *
1487 * This is a practical problem when there is a 64bit big endian kernel
1488 * and a 32bit userspace. As the 32bit address will encoded in the low
1489 * 32bits of the pointer. Those low 32bits will be stored at higher
1490 * address than appear in a 32 bit pointer. So userspace will not
1491 * see the address it was expecting for it's completions.
1492 *
1493 * There is nothing in the encoding that can allow
1494 * copy_siginfo_to_user32 to detect this confusion of formats, so
1495 * handle this by requiring the caller of kill_pid_usb_asyncio to
1496 * notice when this situration takes place and to store the 32bit
1497 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1498 * parameter.
1499 */
1500int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1501 struct pid *pid, const struct cred *cred)
1502{
1503 struct kernel_siginfo info;
1504 struct task_struct *p;
1505 unsigned long flags;
1506 int ret = -EINVAL;
1507
1508 clear_siginfo(&info);
1509 info.si_signo = sig;
1510 info.si_errno = errno;
1511 info.si_code = SI_ASYNCIO;
1512 *((sigval_t *)&info.si_pid) = addr;
1513
1514 if (!valid_signal(sig))
1515 return ret;
1516
1517 rcu_read_lock();
1518 p = pid_task(pid, PIDTYPE_PID);
1519 if (!p) {
1520 ret = -ESRCH;
1521 goto out_unlock;
1522 }
1523 if (!kill_as_cred_perm(cred, p)) {
1524 ret = -EPERM;
1525 goto out_unlock;
1526 }
1527 ret = security_task_kill(p, &info, sig, cred);
1528 if (ret)
1529 goto out_unlock;
1530
1531 if (sig) {
1532 if (lock_task_sighand(p, &flags)) {
1533 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1534 unlock_task_sighand(p, &flags);
1535 } else
1536 ret = -ESRCH;
1537 }
1538out_unlock:
1539 rcu_read_unlock();
1540 return ret;
1541}
1542EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1543
1544/*
1545 * kill_something_info() interprets pid in interesting ways just like kill(2).
1546 *
1547 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1548 * is probably wrong. Should make it like BSD or SYSV.
1549 */
1550
1551static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1552{
1553 int ret;
1554
1555 if (pid > 0) {
1556 rcu_read_lock();
1557 ret = kill_pid_info(sig, info, find_vpid(pid));
1558 rcu_read_unlock();
1559 return ret;
1560 }
1561
1562 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1563 if (pid == INT_MIN)
1564 return -ESRCH;
1565
1566 read_lock(&tasklist_lock);
1567 if (pid != -1) {
1568 ret = __kill_pgrp_info(sig, info,
1569 pid ? find_vpid(-pid) : task_pgrp(current));
1570 } else {
1571 int retval = 0, count = 0;
1572 struct task_struct * p;
1573
1574 for_each_process(p) {
1575 if (task_pid_vnr(p) > 1 &&
1576 !same_thread_group(p, current)) {
1577 int err = group_send_sig_info(sig, info, p,
1578 PIDTYPE_MAX);
1579 ++count;
1580 if (err != -EPERM)
1581 retval = err;
1582 }
1583 }
1584 ret = count ? retval : -ESRCH;
1585 }
1586 read_unlock(&tasklist_lock);
1587
1588 return ret;
1589}
1590
1591/*
1592 * These are for backward compatibility with the rest of the kernel source.
1593 */
1594
1595int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1596{
1597 /*
1598 * Make sure legacy kernel users don't send in bad values
1599 * (normal paths check this in check_kill_permission).
1600 */
1601 if (!valid_signal(sig))
1602 return -EINVAL;
1603
1604 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1605}
1606EXPORT_SYMBOL(send_sig_info);
1607
1608#define __si_special(priv) \
1609 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1610
1611int
1612send_sig(int sig, struct task_struct *p, int priv)
1613{
1614 return send_sig_info(sig, __si_special(priv), p);
1615}
1616EXPORT_SYMBOL(send_sig);
1617
1618void force_sig(int sig)
1619{
1620 struct kernel_siginfo info;
1621
1622 clear_siginfo(&info);
1623 info.si_signo = sig;
1624 info.si_errno = 0;
1625 info.si_code = SI_KERNEL;
1626 info.si_pid = 0;
1627 info.si_uid = 0;
1628 force_sig_info(&info);
1629}
1630EXPORT_SYMBOL(force_sig);
1631
1632/*
1633 * When things go south during signal handling, we
1634 * will force a SIGSEGV. And if the signal that caused
1635 * the problem was already a SIGSEGV, we'll want to
1636 * make sure we don't even try to deliver the signal..
1637 */
1638void force_sigsegv(int sig)
1639{
1640 struct task_struct *p = current;
1641
1642 if (sig == SIGSEGV) {
1643 unsigned long flags;
1644 spin_lock_irqsave(&p->sighand->siglock, flags);
1645 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1646 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1647 }
1648 force_sig(SIGSEGV);
1649}
1650
1651int force_sig_fault_to_task(int sig, int code, void __user *addr
1652 ___ARCH_SI_TRAPNO(int trapno)
1653 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1654 , struct task_struct *t)
1655{
1656 struct kernel_siginfo info;
1657
1658 clear_siginfo(&info);
1659 info.si_signo = sig;
1660 info.si_errno = 0;
1661 info.si_code = code;
1662 info.si_addr = addr;
1663#ifdef __ARCH_SI_TRAPNO
1664 info.si_trapno = trapno;
1665#endif
1666#ifdef __ia64__
1667 info.si_imm = imm;
1668 info.si_flags = flags;
1669 info.si_isr = isr;
1670#endif
1671 return force_sig_info_to_task(&info, t);
1672}
1673
1674int force_sig_fault(int sig, int code, void __user *addr
1675 ___ARCH_SI_TRAPNO(int trapno)
1676 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1677{
1678 return force_sig_fault_to_task(sig, code, addr
1679 ___ARCH_SI_TRAPNO(trapno)
1680 ___ARCH_SI_IA64(imm, flags, isr), current);
1681}
1682
1683int send_sig_fault(int sig, int code, void __user *addr
1684 ___ARCH_SI_TRAPNO(int trapno)
1685 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1686 , struct task_struct *t)
1687{
1688 struct kernel_siginfo info;
1689
1690 clear_siginfo(&info);
1691 info.si_signo = sig;
1692 info.si_errno = 0;
1693 info.si_code = code;
1694 info.si_addr = addr;
1695#ifdef __ARCH_SI_TRAPNO
1696 info.si_trapno = trapno;
1697#endif
1698#ifdef __ia64__
1699 info.si_imm = imm;
1700 info.si_flags = flags;
1701 info.si_isr = isr;
1702#endif
1703 return send_sig_info(info.si_signo, &info, t);
1704}
1705
1706int force_sig_mceerr(int code, void __user *addr, short lsb)
1707{
1708 struct kernel_siginfo info;
1709
1710 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1711 clear_siginfo(&info);
1712 info.si_signo = SIGBUS;
1713 info.si_errno = 0;
1714 info.si_code = code;
1715 info.si_addr = addr;
1716 info.si_addr_lsb = lsb;
1717 return force_sig_info(&info);
1718}
1719
1720int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1721{
1722 struct kernel_siginfo info;
1723
1724 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1725 clear_siginfo(&info);
1726 info.si_signo = SIGBUS;
1727 info.si_errno = 0;
1728 info.si_code = code;
1729 info.si_addr = addr;
1730 info.si_addr_lsb = lsb;
1731 return send_sig_info(info.si_signo, &info, t);
1732}
1733EXPORT_SYMBOL(send_sig_mceerr);
1734
1735int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1736{
1737 struct kernel_siginfo info;
1738
1739 clear_siginfo(&info);
1740 info.si_signo = SIGSEGV;
1741 info.si_errno = 0;
1742 info.si_code = SEGV_BNDERR;
1743 info.si_addr = addr;
1744 info.si_lower = lower;
1745 info.si_upper = upper;
1746 return force_sig_info(&info);
1747}
1748
1749#ifdef SEGV_PKUERR
1750int force_sig_pkuerr(void __user *addr, u32 pkey)
1751{
1752 struct kernel_siginfo info;
1753
1754 clear_siginfo(&info);
1755 info.si_signo = SIGSEGV;
1756 info.si_errno = 0;
1757 info.si_code = SEGV_PKUERR;
1758 info.si_addr = addr;
1759 info.si_pkey = pkey;
1760 return force_sig_info(&info);
1761}
1762#endif
1763
1764/* For the crazy architectures that include trap information in
1765 * the errno field, instead of an actual errno value.
1766 */
1767int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1768{
1769 struct kernel_siginfo info;
1770
1771 clear_siginfo(&info);
1772 info.si_signo = SIGTRAP;
1773 info.si_errno = errno;
1774 info.si_code = TRAP_HWBKPT;
1775 info.si_addr = addr;
1776 return force_sig_info(&info);
1777}
1778
1779int kill_pgrp(struct pid *pid, int sig, int priv)
1780{
1781 int ret;
1782
1783 read_lock(&tasklist_lock);
1784 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1785 read_unlock(&tasklist_lock);
1786
1787 return ret;
1788}
1789EXPORT_SYMBOL(kill_pgrp);
1790
1791int kill_pid(struct pid *pid, int sig, int priv)
1792{
1793 return kill_pid_info(sig, __si_special(priv), pid);
1794}
1795EXPORT_SYMBOL(kill_pid);
1796
1797/*
1798 * These functions support sending signals using preallocated sigqueue
1799 * structures. This is needed "because realtime applications cannot
1800 * afford to lose notifications of asynchronous events, like timer
1801 * expirations or I/O completions". In the case of POSIX Timers
1802 * we allocate the sigqueue structure from the timer_create. If this
1803 * allocation fails we are able to report the failure to the application
1804 * with an EAGAIN error.
1805 */
1806struct sigqueue *sigqueue_alloc(void)
1807{
1808 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1809
1810 if (q)
1811 q->flags |= SIGQUEUE_PREALLOC;
1812
1813 return q;
1814}
1815
1816void sigqueue_free(struct sigqueue *q)
1817{
1818 unsigned long flags;
1819 spinlock_t *lock = ¤t->sighand->siglock;
1820
1821 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1822 /*
1823 * We must hold ->siglock while testing q->list
1824 * to serialize with collect_signal() or with
1825 * __exit_signal()->flush_sigqueue().
1826 */
1827 spin_lock_irqsave(lock, flags);
1828 q->flags &= ~SIGQUEUE_PREALLOC;
1829 /*
1830 * If it is queued it will be freed when dequeued,
1831 * like the "regular" sigqueue.
1832 */
1833 if (!list_empty(&q->list))
1834 q = NULL;
1835 spin_unlock_irqrestore(lock, flags);
1836
1837 if (q)
1838 __sigqueue_free(q);
1839}
1840
1841int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1842{
1843 int sig = q->info.si_signo;
1844 struct sigpending *pending;
1845 struct task_struct *t;
1846 unsigned long flags;
1847 int ret, result;
1848
1849 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1850
1851 ret = -1;
1852 rcu_read_lock();
1853 t = pid_task(pid, type);
1854 if (!t || !likely(lock_task_sighand(t, &flags)))
1855 goto ret;
1856
1857 ret = 1; /* the signal is ignored */
1858 result = TRACE_SIGNAL_IGNORED;
1859 if (!prepare_signal(sig, t, false))
1860 goto out;
1861
1862 ret = 0;
1863 if (unlikely(!list_empty(&q->list))) {
1864 /*
1865 * If an SI_TIMER entry is already queue just increment
1866 * the overrun count.
1867 */
1868 BUG_ON(q->info.si_code != SI_TIMER);
1869 q->info.si_overrun++;
1870 result = TRACE_SIGNAL_ALREADY_PENDING;
1871 goto out;
1872 }
1873 q->info.si_overrun = 0;
1874
1875 signalfd_notify(t, sig);
1876 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1877 list_add_tail(&q->list, &pending->list);
1878 sigaddset(&pending->signal, sig);
1879 complete_signal(sig, t, type);
1880 result = TRACE_SIGNAL_DELIVERED;
1881out:
1882 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1883 unlock_task_sighand(t, &flags);
1884ret:
1885 rcu_read_unlock();
1886 return ret;
1887}
1888
1889static void do_notify_pidfd(struct task_struct *task)
1890{
1891 struct pid *pid;
1892
1893 WARN_ON(task->exit_state == 0);
1894 pid = task_pid(task);
1895 wake_up_all(&pid->wait_pidfd);
1896}
1897
1898/*
1899 * Let a parent know about the death of a child.
1900 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1901 *
1902 * Returns true if our parent ignored us and so we've switched to
1903 * self-reaping.
1904 */
1905bool do_notify_parent(struct task_struct *tsk, int sig)
1906{
1907 struct kernel_siginfo info;
1908 unsigned long flags;
1909 struct sighand_struct *psig;
1910 bool autoreap = false;
1911 u64 utime, stime;
1912
1913 BUG_ON(sig == -1);
1914
1915 /* do_notify_parent_cldstop should have been called instead. */
1916 BUG_ON(task_is_stopped_or_traced(tsk));
1917
1918 BUG_ON(!tsk->ptrace &&
1919 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1920
1921 /* Wake up all pidfd waiters */
1922 do_notify_pidfd(tsk);
1923
1924 if (sig != SIGCHLD) {
1925 /*
1926 * This is only possible if parent == real_parent.
1927 * Check if it has changed security domain.
1928 */
1929 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1930 sig = SIGCHLD;
1931 }
1932
1933 clear_siginfo(&info);
1934 info.si_signo = sig;
1935 info.si_errno = 0;
1936 /*
1937 * We are under tasklist_lock here so our parent is tied to
1938 * us and cannot change.
1939 *
1940 * task_active_pid_ns will always return the same pid namespace
1941 * until a task passes through release_task.
1942 *
1943 * write_lock() currently calls preempt_disable() which is the
1944 * same as rcu_read_lock(), but according to Oleg, this is not
1945 * correct to rely on this
1946 */
1947 rcu_read_lock();
1948 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1949 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1950 task_uid(tsk));
1951 rcu_read_unlock();
1952
1953 task_cputime(tsk, &utime, &stime);
1954 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1955 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1956
1957 info.si_status = tsk->exit_code & 0x7f;
1958 if (tsk->exit_code & 0x80)
1959 info.si_code = CLD_DUMPED;
1960 else if (tsk->exit_code & 0x7f)
1961 info.si_code = CLD_KILLED;
1962 else {
1963 info.si_code = CLD_EXITED;
1964 info.si_status = tsk->exit_code >> 8;
1965 }
1966
1967 psig = tsk->parent->sighand;
1968 spin_lock_irqsave(&psig->siglock, flags);
1969 if (!tsk->ptrace && sig == SIGCHLD &&
1970 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1971 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1972 /*
1973 * We are exiting and our parent doesn't care. POSIX.1
1974 * defines special semantics for setting SIGCHLD to SIG_IGN
1975 * or setting the SA_NOCLDWAIT flag: we should be reaped
1976 * automatically and not left for our parent's wait4 call.
1977 * Rather than having the parent do it as a magic kind of
1978 * signal handler, we just set this to tell do_exit that we
1979 * can be cleaned up without becoming a zombie. Note that
1980 * we still call __wake_up_parent in this case, because a
1981 * blocked sys_wait4 might now return -ECHILD.
1982 *
1983 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1984 * is implementation-defined: we do (if you don't want
1985 * it, just use SIG_IGN instead).
1986 */
1987 autoreap = true;
1988 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1989 sig = 0;
1990 }
1991 if (valid_signal(sig) && sig)
1992 __group_send_sig_info(sig, &info, tsk->parent);
1993 __wake_up_parent(tsk, tsk->parent);
1994 spin_unlock_irqrestore(&psig->siglock, flags);
1995
1996 return autoreap;
1997}
1998
1999/**
2000 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2001 * @tsk: task reporting the state change
2002 * @for_ptracer: the notification is for ptracer
2003 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2004 *
2005 * Notify @tsk's parent that the stopped/continued state has changed. If
2006 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2007 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2008 *
2009 * CONTEXT:
2010 * Must be called with tasklist_lock at least read locked.
2011 */
2012static void do_notify_parent_cldstop(struct task_struct *tsk,
2013 bool for_ptracer, int why)
2014{
2015 struct kernel_siginfo info;
2016 unsigned long flags;
2017 struct task_struct *parent;
2018 struct sighand_struct *sighand;
2019 u64 utime, stime;
2020
2021 if (for_ptracer) {
2022 parent = tsk->parent;
2023 } else {
2024 tsk = tsk->group_leader;
2025 parent = tsk->real_parent;
2026 }
2027
2028 clear_siginfo(&info);
2029 info.si_signo = SIGCHLD;
2030 info.si_errno = 0;
2031 /*
2032 * see comment in do_notify_parent() about the following 4 lines
2033 */
2034 rcu_read_lock();
2035 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2036 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2037 rcu_read_unlock();
2038
2039 task_cputime(tsk, &utime, &stime);
2040 info.si_utime = nsec_to_clock_t(utime);
2041 info.si_stime = nsec_to_clock_t(stime);
2042
2043 info.si_code = why;
2044 switch (why) {
2045 case CLD_CONTINUED:
2046 info.si_status = SIGCONT;
2047 break;
2048 case CLD_STOPPED:
2049 info.si_status = tsk->signal->group_exit_code & 0x7f;
2050 break;
2051 case CLD_TRAPPED:
2052 info.si_status = tsk->exit_code & 0x7f;
2053 break;
2054 default:
2055 BUG();
2056 }
2057
2058 sighand = parent->sighand;
2059 spin_lock_irqsave(&sighand->siglock, flags);
2060 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2061 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2062 __group_send_sig_info(SIGCHLD, &info, parent);
2063 /*
2064 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2065 */
2066 __wake_up_parent(tsk, parent);
2067 spin_unlock_irqrestore(&sighand->siglock, flags);
2068}
2069
2070static inline bool may_ptrace_stop(void)
2071{
2072 if (!likely(current->ptrace))
2073 return false;
2074 /*
2075 * Are we in the middle of do_coredump?
2076 * If so and our tracer is also part of the coredump stopping
2077 * is a deadlock situation, and pointless because our tracer
2078 * is dead so don't allow us to stop.
2079 * If SIGKILL was already sent before the caller unlocked
2080 * ->siglock we must see ->core_state != NULL. Otherwise it
2081 * is safe to enter schedule().
2082 *
2083 * This is almost outdated, a task with the pending SIGKILL can't
2084 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
2085 * after SIGKILL was already dequeued.
2086 */
2087 if (unlikely(current->mm->core_state) &&
2088 unlikely(current->mm == current->parent->mm))
2089 return false;
2090
2091 return true;
2092}
2093
2094/*
2095 * Return non-zero if there is a SIGKILL that should be waking us up.
2096 * Called with the siglock held.
2097 */
2098static bool sigkill_pending(struct task_struct *tsk)
2099{
2100 return sigismember(&tsk->pending.signal, SIGKILL) ||
2101 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
2102}
2103
2104/*
2105 * This must be called with current->sighand->siglock held.
2106 *
2107 * This should be the path for all ptrace stops.
2108 * We always set current->last_siginfo while stopped here.
2109 * That makes it a way to test a stopped process for
2110 * being ptrace-stopped vs being job-control-stopped.
2111 *
2112 * If we actually decide not to stop at all because the tracer
2113 * is gone, we keep current->exit_code unless clear_code.
2114 */
2115static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
2116 __releases(¤t->sighand->siglock)
2117 __acquires(¤t->sighand->siglock)
2118{
2119 bool gstop_done = false;
2120
2121 if (arch_ptrace_stop_needed(exit_code, info)) {
2122 /*
2123 * The arch code has something special to do before a
2124 * ptrace stop. This is allowed to block, e.g. for faults
2125 * on user stack pages. We can't keep the siglock while
2126 * calling arch_ptrace_stop, so we must release it now.
2127 * To preserve proper semantics, we must do this before
2128 * any signal bookkeeping like checking group_stop_count.
2129 * Meanwhile, a SIGKILL could come in before we retake the
2130 * siglock. That must prevent us from sleeping in TASK_TRACED.
2131 * So after regaining the lock, we must check for SIGKILL.
2132 */
2133 spin_unlock_irq(¤t->sighand->siglock);
2134 arch_ptrace_stop(exit_code, info);
2135 spin_lock_irq(¤t->sighand->siglock);
2136 if (sigkill_pending(current))
2137 return;
2138 }
2139
2140 set_special_state(TASK_TRACED);
2141
2142 /*
2143 * We're committing to trapping. TRACED should be visible before
2144 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2145 * Also, transition to TRACED and updates to ->jobctl should be
2146 * atomic with respect to siglock and should be done after the arch
2147 * hook as siglock is released and regrabbed across it.
2148 *
2149 * TRACER TRACEE
2150 *
2151 * ptrace_attach()
2152 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2153 * do_wait()
2154 * set_current_state() smp_wmb();
2155 * ptrace_do_wait()
2156 * wait_task_stopped()
2157 * task_stopped_code()
2158 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2159 */
2160 smp_wmb();
2161
2162 current->last_siginfo = info;
2163 current->exit_code = exit_code;
2164
2165 /*
2166 * If @why is CLD_STOPPED, we're trapping to participate in a group
2167 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2168 * across siglock relocks since INTERRUPT was scheduled, PENDING
2169 * could be clear now. We act as if SIGCONT is received after
2170 * TASK_TRACED is entered - ignore it.
2171 */
2172 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2173 gstop_done = task_participate_group_stop(current);
2174
2175 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2176 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2177 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2178 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2179
2180 /* entering a trap, clear TRAPPING */
2181 task_clear_jobctl_trapping(current);
2182
2183 spin_unlock_irq(¤t->sighand->siglock);
2184 read_lock(&tasklist_lock);
2185 if (may_ptrace_stop()) {
2186 /*
2187 * Notify parents of the stop.
2188 *
2189 * While ptraced, there are two parents - the ptracer and
2190 * the real_parent of the group_leader. The ptracer should
2191 * know about every stop while the real parent is only
2192 * interested in the completion of group stop. The states
2193 * for the two don't interact with each other. Notify
2194 * separately unless they're gonna be duplicates.
2195 */
2196 do_notify_parent_cldstop(current, true, why);
2197 if (gstop_done && ptrace_reparented(current))
2198 do_notify_parent_cldstop(current, false, why);
2199
2200 /*
2201 * Don't want to allow preemption here, because
2202 * sys_ptrace() needs this task to be inactive.
2203 *
2204 * XXX: implement read_unlock_no_resched().
2205 */
2206 preempt_disable();
2207 read_unlock(&tasklist_lock);
2208 cgroup_enter_frozen();
2209 preempt_enable_no_resched();
2210 freezable_schedule();
2211 cgroup_leave_frozen(true);
2212 } else {
2213 /*
2214 * By the time we got the lock, our tracer went away.
2215 * Don't drop the lock yet, another tracer may come.
2216 *
2217 * If @gstop_done, the ptracer went away between group stop
2218 * completion and here. During detach, it would have set
2219 * JOBCTL_STOP_PENDING on us and we'll re-enter
2220 * TASK_STOPPED in do_signal_stop() on return, so notifying
2221 * the real parent of the group stop completion is enough.
2222 */
2223 if (gstop_done)
2224 do_notify_parent_cldstop(current, false, why);
2225
2226 /* tasklist protects us from ptrace_freeze_traced() */
2227 __set_current_state(TASK_RUNNING);
2228 if (clear_code)
2229 current->exit_code = 0;
2230 read_unlock(&tasklist_lock);
2231 }
2232
2233 /*
2234 * We are back. Now reacquire the siglock before touching
2235 * last_siginfo, so that we are sure to have synchronized with
2236 * any signal-sending on another CPU that wants to examine it.
2237 */
2238 spin_lock_irq(¤t->sighand->siglock);
2239 current->last_siginfo = NULL;
2240
2241 /* LISTENING can be set only during STOP traps, clear it */
2242 current->jobctl &= ~JOBCTL_LISTENING;
2243
2244 /*
2245 * Queued signals ignored us while we were stopped for tracing.
2246 * So check for any that we should take before resuming user mode.
2247 * This sets TIF_SIGPENDING, but never clears it.
2248 */
2249 recalc_sigpending_tsk(current);
2250}
2251
2252static void ptrace_do_notify(int signr, int exit_code, int why)
2253{
2254 kernel_siginfo_t info;
2255
2256 clear_siginfo(&info);
2257 info.si_signo = signr;
2258 info.si_code = exit_code;
2259 info.si_pid = task_pid_vnr(current);
2260 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2261
2262 /* Let the debugger run. */
2263 ptrace_stop(exit_code, why, 1, &info);
2264}
2265
2266void ptrace_notify(int exit_code)
2267{
2268 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2269 if (unlikely(current->task_works))
2270 task_work_run();
2271
2272 spin_lock_irq(¤t->sighand->siglock);
2273 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2274 spin_unlock_irq(¤t->sighand->siglock);
2275}
2276
2277/**
2278 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2279 * @signr: signr causing group stop if initiating
2280 *
2281 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2282 * and participate in it. If already set, participate in the existing
2283 * group stop. If participated in a group stop (and thus slept), %true is
2284 * returned with siglock released.
2285 *
2286 * If ptraced, this function doesn't handle stop itself. Instead,
2287 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2288 * untouched. The caller must ensure that INTERRUPT trap handling takes
2289 * places afterwards.
2290 *
2291 * CONTEXT:
2292 * Must be called with @current->sighand->siglock held, which is released
2293 * on %true return.
2294 *
2295 * RETURNS:
2296 * %false if group stop is already cancelled or ptrace trap is scheduled.
2297 * %true if participated in group stop.
2298 */
2299static bool do_signal_stop(int signr)
2300 __releases(¤t->sighand->siglock)
2301{
2302 struct signal_struct *sig = current->signal;
2303
2304 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2305 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2306 struct task_struct *t;
2307
2308 /* signr will be recorded in task->jobctl for retries */
2309 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2310
2311 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2312 unlikely(signal_group_exit(sig)))
2313 return false;
2314 /*
2315 * There is no group stop already in progress. We must
2316 * initiate one now.
2317 *
2318 * While ptraced, a task may be resumed while group stop is
2319 * still in effect and then receive a stop signal and
2320 * initiate another group stop. This deviates from the
2321 * usual behavior as two consecutive stop signals can't
2322 * cause two group stops when !ptraced. That is why we
2323 * also check !task_is_stopped(t) below.
2324 *
2325 * The condition can be distinguished by testing whether
2326 * SIGNAL_STOP_STOPPED is already set. Don't generate
2327 * group_exit_code in such case.
2328 *
2329 * This is not necessary for SIGNAL_STOP_CONTINUED because
2330 * an intervening stop signal is required to cause two
2331 * continued events regardless of ptrace.
2332 */
2333 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2334 sig->group_exit_code = signr;
2335
2336 sig->group_stop_count = 0;
2337
2338 if (task_set_jobctl_pending(current, signr | gstop))
2339 sig->group_stop_count++;
2340
2341 t = current;
2342 while_each_thread(current, t) {
2343 /*
2344 * Setting state to TASK_STOPPED for a group
2345 * stop is always done with the siglock held,
2346 * so this check has no races.
2347 */
2348 if (!task_is_stopped(t) &&
2349 task_set_jobctl_pending(t, signr | gstop)) {
2350 sig->group_stop_count++;
2351 if (likely(!(t->ptrace & PT_SEIZED)))
2352 signal_wake_up(t, 0);
2353 else
2354 ptrace_trap_notify(t);
2355 }
2356 }
2357 }
2358
2359 if (likely(!current->ptrace)) {
2360 int notify = 0;
2361
2362 /*
2363 * If there are no other threads in the group, or if there
2364 * is a group stop in progress and we are the last to stop,
2365 * report to the parent.
2366 */
2367 if (task_participate_group_stop(current))
2368 notify = CLD_STOPPED;
2369
2370 set_special_state(TASK_STOPPED);
2371 spin_unlock_irq(¤t->sighand->siglock);
2372
2373 /*
2374 * Notify the parent of the group stop completion. Because
2375 * we're not holding either the siglock or tasklist_lock
2376 * here, ptracer may attach inbetween; however, this is for
2377 * group stop and should always be delivered to the real
2378 * parent of the group leader. The new ptracer will get
2379 * its notification when this task transitions into
2380 * TASK_TRACED.
2381 */
2382 if (notify) {
2383 read_lock(&tasklist_lock);
2384 do_notify_parent_cldstop(current, false, notify);
2385 read_unlock(&tasklist_lock);
2386 }
2387
2388 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2389 cgroup_enter_frozen();
2390 freezable_schedule();
2391 return true;
2392 } else {
2393 /*
2394 * While ptraced, group stop is handled by STOP trap.
2395 * Schedule it and let the caller deal with it.
2396 */
2397 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2398 return false;
2399 }
2400}
2401
2402/**
2403 * do_jobctl_trap - take care of ptrace jobctl traps
2404 *
2405 * When PT_SEIZED, it's used for both group stop and explicit
2406 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2407 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2408 * the stop signal; otherwise, %SIGTRAP.
2409 *
2410 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2411 * number as exit_code and no siginfo.
2412 *
2413 * CONTEXT:
2414 * Must be called with @current->sighand->siglock held, which may be
2415 * released and re-acquired before returning with intervening sleep.
2416 */
2417static void do_jobctl_trap(void)
2418{
2419 struct signal_struct *signal = current->signal;
2420 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2421
2422 if (current->ptrace & PT_SEIZED) {
2423 if (!signal->group_stop_count &&
2424 !(signal->flags & SIGNAL_STOP_STOPPED))
2425 signr = SIGTRAP;
2426 WARN_ON_ONCE(!signr);
2427 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2428 CLD_STOPPED);
2429 } else {
2430 WARN_ON_ONCE(!signr);
2431 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2432 current->exit_code = 0;
2433 }
2434}
2435
2436/**
2437 * do_freezer_trap - handle the freezer jobctl trap
2438 *
2439 * Puts the task into frozen state, if only the task is not about to quit.
2440 * In this case it drops JOBCTL_TRAP_FREEZE.
2441 *
2442 * CONTEXT:
2443 * Must be called with @current->sighand->siglock held,
2444 * which is always released before returning.
2445 */
2446static void do_freezer_trap(void)
2447 __releases(¤t->sighand->siglock)
2448{
2449 /*
2450 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2451 * let's make another loop to give it a chance to be handled.
2452 * In any case, we'll return back.
2453 */
2454 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2455 JOBCTL_TRAP_FREEZE) {
2456 spin_unlock_irq(¤t->sighand->siglock);
2457 return;
2458 }
2459
2460 /*
2461 * Now we're sure that there is no pending fatal signal and no
2462 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2463 * immediately (if there is a non-fatal signal pending), and
2464 * put the task into sleep.
2465 */
2466 __set_current_state(TASK_INTERRUPTIBLE);
2467 clear_thread_flag(TIF_SIGPENDING);
2468 spin_unlock_irq(¤t->sighand->siglock);
2469 cgroup_enter_frozen();
2470 freezable_schedule();
2471}
2472
2473static int ptrace_signal(int signr, kernel_siginfo_t *info)
2474{
2475 /*
2476 * We do not check sig_kernel_stop(signr) but set this marker
2477 * unconditionally because we do not know whether debugger will
2478 * change signr. This flag has no meaning unless we are going
2479 * to stop after return from ptrace_stop(). In this case it will
2480 * be checked in do_signal_stop(), we should only stop if it was
2481 * not cleared by SIGCONT while we were sleeping. See also the
2482 * comment in dequeue_signal().
2483 */
2484 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2485 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2486
2487 /* We're back. Did the debugger cancel the sig? */
2488 signr = current->exit_code;
2489 if (signr == 0)
2490 return signr;
2491
2492 current->exit_code = 0;
2493
2494 /*
2495 * Update the siginfo structure if the signal has
2496 * changed. If the debugger wanted something
2497 * specific in the siginfo structure then it should
2498 * have updated *info via PTRACE_SETSIGINFO.
2499 */
2500 if (signr != info->si_signo) {
2501 clear_siginfo(info);
2502 info->si_signo = signr;
2503 info->si_errno = 0;
2504 info->si_code = SI_USER;
2505 rcu_read_lock();
2506 info->si_pid = task_pid_vnr(current->parent);
2507 info->si_uid = from_kuid_munged(current_user_ns(),
2508 task_uid(current->parent));
2509 rcu_read_unlock();
2510 }
2511
2512 /* If the (new) signal is now blocked, requeue it. */
2513 if (sigismember(¤t->blocked, signr)) {
2514 send_signal(signr, info, current, PIDTYPE_PID);
2515 signr = 0;
2516 }
2517
2518 return signr;
2519}
2520
2521bool get_signal(struct ksignal *ksig)
2522{
2523 struct sighand_struct *sighand = current->sighand;
2524 struct signal_struct *signal = current->signal;
2525 int signr;
2526
2527 if (unlikely(current->task_works))
2528 task_work_run();
2529
2530 if (unlikely(uprobe_deny_signal()))
2531 return false;
2532
2533 /*
2534 * Do this once, we can't return to user-mode if freezing() == T.
2535 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2536 * thus do not need another check after return.
2537 */
2538 try_to_freeze();
2539
2540relock:
2541 spin_lock_irq(&sighand->siglock);
2542 /*
2543 * Every stopped thread goes here after wakeup. Check to see if
2544 * we should notify the parent, prepare_signal(SIGCONT) encodes
2545 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2546 */
2547 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2548 int why;
2549
2550 if (signal->flags & SIGNAL_CLD_CONTINUED)
2551 why = CLD_CONTINUED;
2552 else
2553 why = CLD_STOPPED;
2554
2555 signal->flags &= ~SIGNAL_CLD_MASK;
2556
2557 spin_unlock_irq(&sighand->siglock);
2558
2559 /*
2560 * Notify the parent that we're continuing. This event is
2561 * always per-process and doesn't make whole lot of sense
2562 * for ptracers, who shouldn't consume the state via
2563 * wait(2) either, but, for backward compatibility, notify
2564 * the ptracer of the group leader too unless it's gonna be
2565 * a duplicate.
2566 */
2567 read_lock(&tasklist_lock);
2568 do_notify_parent_cldstop(current, false, why);
2569
2570 if (ptrace_reparented(current->group_leader))
2571 do_notify_parent_cldstop(current->group_leader,
2572 true, why);
2573 read_unlock(&tasklist_lock);
2574
2575 goto relock;
2576 }
2577
2578 /* Has this task already been marked for death? */
2579 if (signal_group_exit(signal)) {
2580 ksig->info.si_signo = signr = SIGKILL;
2581 sigdelset(¤t->pending.signal, SIGKILL);
2582 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2583 &sighand->action[SIGKILL - 1]);
2584 recalc_sigpending();
2585 goto fatal;
2586 }
2587
2588 for (;;) {
2589 struct k_sigaction *ka;
2590
2591 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2592 do_signal_stop(0))
2593 goto relock;
2594
2595 if (unlikely(current->jobctl &
2596 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2597 if (current->jobctl & JOBCTL_TRAP_MASK) {
2598 do_jobctl_trap();
2599 spin_unlock_irq(&sighand->siglock);
2600 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2601 do_freezer_trap();
2602
2603 goto relock;
2604 }
2605
2606 /*
2607 * If the task is leaving the frozen state, let's update
2608 * cgroup counters and reset the frozen bit.
2609 */
2610 if (unlikely(cgroup_task_frozen(current))) {
2611 spin_unlock_irq(&sighand->siglock);
2612 cgroup_leave_frozen(false);
2613 goto relock;
2614 }
2615
2616 /*
2617 * Signals generated by the execution of an instruction
2618 * need to be delivered before any other pending signals
2619 * so that the instruction pointer in the signal stack
2620 * frame points to the faulting instruction.
2621 */
2622 signr = dequeue_synchronous_signal(&ksig->info);
2623 if (!signr)
2624 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2625
2626 if (!signr)
2627 break; /* will return 0 */
2628
2629 if (unlikely(current->ptrace) && signr != SIGKILL) {
2630 signr = ptrace_signal(signr, &ksig->info);
2631 if (!signr)
2632 continue;
2633 }
2634
2635 ka = &sighand->action[signr-1];
2636
2637 /* Trace actually delivered signals. */
2638 trace_signal_deliver(signr, &ksig->info, ka);
2639
2640 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2641 continue;
2642 if (ka->sa.sa_handler != SIG_DFL) {
2643 /* Run the handler. */
2644 ksig->ka = *ka;
2645
2646 if (ka->sa.sa_flags & SA_ONESHOT)
2647 ka->sa.sa_handler = SIG_DFL;
2648
2649 break; /* will return non-zero "signr" value */
2650 }
2651
2652 /*
2653 * Now we are doing the default action for this signal.
2654 */
2655 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2656 continue;
2657
2658 /*
2659 * Global init gets no signals it doesn't want.
2660 * Container-init gets no signals it doesn't want from same
2661 * container.
2662 *
2663 * Note that if global/container-init sees a sig_kernel_only()
2664 * signal here, the signal must have been generated internally
2665 * or must have come from an ancestor namespace. In either
2666 * case, the signal cannot be dropped.
2667 */
2668 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2669 !sig_kernel_only(signr))
2670 continue;
2671
2672 if (sig_kernel_stop(signr)) {
2673 /*
2674 * The default action is to stop all threads in
2675 * the thread group. The job control signals
2676 * do nothing in an orphaned pgrp, but SIGSTOP
2677 * always works. Note that siglock needs to be
2678 * dropped during the call to is_orphaned_pgrp()
2679 * because of lock ordering with tasklist_lock.
2680 * This allows an intervening SIGCONT to be posted.
2681 * We need to check for that and bail out if necessary.
2682 */
2683 if (signr != SIGSTOP) {
2684 spin_unlock_irq(&sighand->siglock);
2685
2686 /* signals can be posted during this window */
2687
2688 if (is_current_pgrp_orphaned())
2689 goto relock;
2690
2691 spin_lock_irq(&sighand->siglock);
2692 }
2693
2694 if (likely(do_signal_stop(ksig->info.si_signo))) {
2695 /* It released the siglock. */
2696 goto relock;
2697 }
2698
2699 /*
2700 * We didn't actually stop, due to a race
2701 * with SIGCONT or something like that.
2702 */
2703 continue;
2704 }
2705
2706 fatal:
2707 spin_unlock_irq(&sighand->siglock);
2708 if (unlikely(cgroup_task_frozen(current)))
2709 cgroup_leave_frozen(true);
2710
2711 /*
2712 * Anything else is fatal, maybe with a core dump.
2713 */
2714 current->flags |= PF_SIGNALED;
2715
2716 if (sig_kernel_coredump(signr)) {
2717 if (print_fatal_signals)
2718 print_fatal_signal(ksig->info.si_signo);
2719 proc_coredump_connector(current);
2720 /*
2721 * If it was able to dump core, this kills all
2722 * other threads in the group and synchronizes with
2723 * their demise. If we lost the race with another
2724 * thread getting here, it set group_exit_code
2725 * first and our do_group_exit call below will use
2726 * that value and ignore the one we pass it.
2727 */
2728 do_coredump(&ksig->info);
2729 }
2730
2731 /*
2732 * Death signals, no core dump.
2733 */
2734 do_group_exit(ksig->info.si_signo);
2735 /* NOTREACHED */
2736 }
2737 spin_unlock_irq(&sighand->siglock);
2738
2739 ksig->sig = signr;
2740 return ksig->sig > 0;
2741}
2742
2743/**
2744 * signal_delivered -
2745 * @ksig: kernel signal struct
2746 * @stepping: nonzero if debugger single-step or block-step in use
2747 *
2748 * This function should be called when a signal has successfully been
2749 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2750 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2751 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2752 */
2753static void signal_delivered(struct ksignal *ksig, int stepping)
2754{
2755 sigset_t blocked;
2756
2757 /* A signal was successfully delivered, and the
2758 saved sigmask was stored on the signal frame,
2759 and will be restored by sigreturn. So we can
2760 simply clear the restore sigmask flag. */
2761 clear_restore_sigmask();
2762
2763 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2764 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2765 sigaddset(&blocked, ksig->sig);
2766 set_current_blocked(&blocked);
2767 tracehook_signal_handler(stepping);
2768}
2769
2770void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2771{
2772 if (failed)
2773 force_sigsegv(ksig->sig);
2774 else
2775 signal_delivered(ksig, stepping);
2776}
2777
2778/*
2779 * It could be that complete_signal() picked us to notify about the
2780 * group-wide signal. Other threads should be notified now to take
2781 * the shared signals in @which since we will not.
2782 */
2783static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2784{
2785 sigset_t retarget;
2786 struct task_struct *t;
2787
2788 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2789 if (sigisemptyset(&retarget))
2790 return;
2791
2792 t = tsk;
2793 while_each_thread(tsk, t) {
2794 if (t->flags & PF_EXITING)
2795 continue;
2796
2797 if (!has_pending_signals(&retarget, &t->blocked))
2798 continue;
2799 /* Remove the signals this thread can handle. */
2800 sigandsets(&retarget, &retarget, &t->blocked);
2801
2802 if (!signal_pending(t))
2803 signal_wake_up(t, 0);
2804
2805 if (sigisemptyset(&retarget))
2806 break;
2807 }
2808}
2809
2810void exit_signals(struct task_struct *tsk)
2811{
2812 int group_stop = 0;
2813 sigset_t unblocked;
2814
2815 /*
2816 * @tsk is about to have PF_EXITING set - lock out users which
2817 * expect stable threadgroup.
2818 */
2819 cgroup_threadgroup_change_begin(tsk);
2820
2821 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2822 tsk->flags |= PF_EXITING;
2823 cgroup_threadgroup_change_end(tsk);
2824 return;
2825 }
2826
2827 spin_lock_irq(&tsk->sighand->siglock);
2828 /*
2829 * From now this task is not visible for group-wide signals,
2830 * see wants_signal(), do_signal_stop().
2831 */
2832 tsk->flags |= PF_EXITING;
2833
2834 cgroup_threadgroup_change_end(tsk);
2835
2836 if (!signal_pending(tsk))
2837 goto out;
2838
2839 unblocked = tsk->blocked;
2840 signotset(&unblocked);
2841 retarget_shared_pending(tsk, &unblocked);
2842
2843 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2844 task_participate_group_stop(tsk))
2845 group_stop = CLD_STOPPED;
2846out:
2847 spin_unlock_irq(&tsk->sighand->siglock);
2848
2849 /*
2850 * If group stop has completed, deliver the notification. This
2851 * should always go to the real parent of the group leader.
2852 */
2853 if (unlikely(group_stop)) {
2854 read_lock(&tasklist_lock);
2855 do_notify_parent_cldstop(tsk, false, group_stop);
2856 read_unlock(&tasklist_lock);
2857 }
2858}
2859
2860/*
2861 * System call entry points.
2862 */
2863
2864/**
2865 * sys_restart_syscall - restart a system call
2866 */
2867SYSCALL_DEFINE0(restart_syscall)
2868{
2869 struct restart_block *restart = ¤t->restart_block;
2870 return restart->fn(restart);
2871}
2872
2873long do_no_restart_syscall(struct restart_block *param)
2874{
2875 return -EINTR;
2876}
2877
2878static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2879{
2880 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2881 sigset_t newblocked;
2882 /* A set of now blocked but previously unblocked signals. */
2883 sigandnsets(&newblocked, newset, ¤t->blocked);
2884 retarget_shared_pending(tsk, &newblocked);
2885 }
2886 tsk->blocked = *newset;
2887 recalc_sigpending();
2888}
2889
2890/**
2891 * set_current_blocked - change current->blocked mask
2892 * @newset: new mask
2893 *
2894 * It is wrong to change ->blocked directly, this helper should be used
2895 * to ensure the process can't miss a shared signal we are going to block.
2896 */
2897void set_current_blocked(sigset_t *newset)
2898{
2899 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2900 __set_current_blocked(newset);
2901}
2902
2903void __set_current_blocked(const sigset_t *newset)
2904{
2905 struct task_struct *tsk = current;
2906
2907 /*
2908 * In case the signal mask hasn't changed, there is nothing we need
2909 * to do. The current->blocked shouldn't be modified by other task.
2910 */
2911 if (sigequalsets(&tsk->blocked, newset))
2912 return;
2913
2914 spin_lock_irq(&tsk->sighand->siglock);
2915 __set_task_blocked(tsk, newset);
2916 spin_unlock_irq(&tsk->sighand->siglock);
2917}
2918
2919/*
2920 * This is also useful for kernel threads that want to temporarily
2921 * (or permanently) block certain signals.
2922 *
2923 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2924 * interface happily blocks "unblockable" signals like SIGKILL
2925 * and friends.
2926 */
2927int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2928{
2929 struct task_struct *tsk = current;
2930 sigset_t newset;
2931
2932 /* Lockless, only current can change ->blocked, never from irq */
2933 if (oldset)
2934 *oldset = tsk->blocked;
2935
2936 switch (how) {
2937 case SIG_BLOCK:
2938 sigorsets(&newset, &tsk->blocked, set);
2939 break;
2940 case SIG_UNBLOCK:
2941 sigandnsets(&newset, &tsk->blocked, set);
2942 break;
2943 case SIG_SETMASK:
2944 newset = *set;
2945 break;
2946 default:
2947 return -EINVAL;
2948 }
2949
2950 __set_current_blocked(&newset);
2951 return 0;
2952}
2953EXPORT_SYMBOL(sigprocmask);
2954
2955/*
2956 * The api helps set app-provided sigmasks.
2957 *
2958 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
2959 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
2960 *
2961 * Note that it does set_restore_sigmask() in advance, so it must be always
2962 * paired with restore_saved_sigmask_unless() before return from syscall.
2963 */
2964int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
2965{
2966 sigset_t kmask;
2967
2968 if (!umask)
2969 return 0;
2970 if (sigsetsize != sizeof(sigset_t))
2971 return -EINVAL;
2972 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
2973 return -EFAULT;
2974
2975 set_restore_sigmask();
2976 current->saved_sigmask = current->blocked;
2977 set_current_blocked(&kmask);
2978
2979 return 0;
2980}
2981
2982#ifdef CONFIG_COMPAT
2983int set_compat_user_sigmask(const compat_sigset_t __user *umask,
2984 size_t sigsetsize)
2985{
2986 sigset_t kmask;
2987
2988 if (!umask)
2989 return 0;
2990 if (sigsetsize != sizeof(compat_sigset_t))
2991 return -EINVAL;
2992 if (get_compat_sigset(&kmask, umask))
2993 return -EFAULT;
2994
2995 set_restore_sigmask();
2996 current->saved_sigmask = current->blocked;
2997 set_current_blocked(&kmask);
2998
2999 return 0;
3000}
3001#endif
3002
3003/**
3004 * sys_rt_sigprocmask - change the list of currently blocked signals
3005 * @how: whether to add, remove, or set signals
3006 * @nset: stores pending signals
3007 * @oset: previous value of signal mask if non-null
3008 * @sigsetsize: size of sigset_t type
3009 */
3010SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3011 sigset_t __user *, oset, size_t, sigsetsize)
3012{
3013 sigset_t old_set, new_set;
3014 int error;
3015
3016 /* XXX: Don't preclude handling different sized sigset_t's. */
3017 if (sigsetsize != sizeof(sigset_t))
3018 return -EINVAL;
3019
3020 old_set = current->blocked;
3021
3022 if (nset) {
3023 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3024 return -EFAULT;
3025 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3026
3027 error = sigprocmask(how, &new_set, NULL);
3028 if (error)
3029 return error;
3030 }
3031
3032 if (oset) {
3033 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3034 return -EFAULT;
3035 }
3036
3037 return 0;
3038}
3039
3040#ifdef CONFIG_COMPAT
3041COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3042 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3043{
3044 sigset_t old_set = current->blocked;
3045
3046 /* XXX: Don't preclude handling different sized sigset_t's. */
3047 if (sigsetsize != sizeof(sigset_t))
3048 return -EINVAL;
3049
3050 if (nset) {
3051 sigset_t new_set;
3052 int error;
3053 if (get_compat_sigset(&new_set, nset))
3054 return -EFAULT;
3055 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3056
3057 error = sigprocmask(how, &new_set, NULL);
3058 if (error)
3059 return error;
3060 }
3061 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3062}
3063#endif
3064
3065static void do_sigpending(sigset_t *set)
3066{
3067 spin_lock_irq(¤t->sighand->siglock);
3068 sigorsets(set, ¤t->pending.signal,
3069 ¤t->signal->shared_pending.signal);
3070 spin_unlock_irq(¤t->sighand->siglock);
3071
3072 /* Outside the lock because only this thread touches it. */
3073 sigandsets(set, ¤t->blocked, set);
3074}
3075
3076/**
3077 * sys_rt_sigpending - examine a pending signal that has been raised
3078 * while blocked
3079 * @uset: stores pending signals
3080 * @sigsetsize: size of sigset_t type or larger
3081 */
3082SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3083{
3084 sigset_t set;
3085
3086 if (sigsetsize > sizeof(*uset))
3087 return -EINVAL;
3088
3089 do_sigpending(&set);
3090
3091 if (copy_to_user(uset, &set, sigsetsize))
3092 return -EFAULT;
3093
3094 return 0;
3095}
3096
3097#ifdef CONFIG_COMPAT
3098COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3099 compat_size_t, sigsetsize)
3100{
3101 sigset_t set;
3102
3103 if (sigsetsize > sizeof(*uset))
3104 return -EINVAL;
3105
3106 do_sigpending(&set);
3107
3108 return put_compat_sigset(uset, &set, sigsetsize);
3109}
3110#endif
3111
3112static const struct {
3113 unsigned char limit, layout;
3114} sig_sicodes[] = {
3115 [SIGILL] = { NSIGILL, SIL_FAULT },
3116 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3117 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3118 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3119 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3120#if defined(SIGEMT)
3121 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3122#endif
3123 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3124 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3125 [SIGSYS] = { NSIGSYS, SIL_SYS },
3126};
3127
3128static bool known_siginfo_layout(unsigned sig, int si_code)
3129{
3130 if (si_code == SI_KERNEL)
3131 return true;
3132 else if ((si_code > SI_USER)) {
3133 if (sig_specific_sicodes(sig)) {
3134 if (si_code <= sig_sicodes[sig].limit)
3135 return true;
3136 }
3137 else if (si_code <= NSIGPOLL)
3138 return true;
3139 }
3140 else if (si_code >= SI_DETHREAD)
3141 return true;
3142 else if (si_code == SI_ASYNCNL)
3143 return true;
3144 return false;
3145}
3146
3147enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3148{
3149 enum siginfo_layout layout = SIL_KILL;
3150 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3151 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3152 (si_code <= sig_sicodes[sig].limit)) {
3153 layout = sig_sicodes[sig].layout;
3154 /* Handle the exceptions */
3155 if ((sig == SIGBUS) &&
3156 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3157 layout = SIL_FAULT_MCEERR;
3158 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3159 layout = SIL_FAULT_BNDERR;
3160#ifdef SEGV_PKUERR
3161 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3162 layout = SIL_FAULT_PKUERR;
3163#endif
3164 }
3165 else if (si_code <= NSIGPOLL)
3166 layout = SIL_POLL;
3167 } else {
3168 if (si_code == SI_TIMER)
3169 layout = SIL_TIMER;
3170 else if (si_code == SI_SIGIO)
3171 layout = SIL_POLL;
3172 else if (si_code < 0)
3173 layout = SIL_RT;
3174 }
3175 return layout;
3176}
3177
3178static inline char __user *si_expansion(const siginfo_t __user *info)
3179{
3180 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3181}
3182
3183int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3184{
3185 char __user *expansion = si_expansion(to);
3186 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3187 return -EFAULT;
3188 if (clear_user(expansion, SI_EXPANSION_SIZE))
3189 return -EFAULT;
3190 return 0;
3191}
3192
3193static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3194 const siginfo_t __user *from)
3195{
3196 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3197 char __user *expansion = si_expansion(from);
3198 char buf[SI_EXPANSION_SIZE];
3199 int i;
3200 /*
3201 * An unknown si_code might need more than
3202 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3203 * extra bytes are 0. This guarantees copy_siginfo_to_user
3204 * will return this data to userspace exactly.
3205 */
3206 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3207 return -EFAULT;
3208 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3209 if (buf[i] != 0)
3210 return -E2BIG;
3211 }
3212 }
3213 return 0;
3214}
3215
3216static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3217 const siginfo_t __user *from)
3218{
3219 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3220 return -EFAULT;
3221 to->si_signo = signo;
3222 return post_copy_siginfo_from_user(to, from);
3223}
3224
3225int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3226{
3227 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3228 return -EFAULT;
3229 return post_copy_siginfo_from_user(to, from);
3230}
3231
3232#ifdef CONFIG_COMPAT
3233int copy_siginfo_to_user32(struct compat_siginfo __user *to,
3234 const struct kernel_siginfo *from)
3235#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
3236{
3237 return __copy_siginfo_to_user32(to, from, in_x32_syscall());
3238}
3239int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3240 const struct kernel_siginfo *from, bool x32_ABI)
3241#endif
3242{
3243 struct compat_siginfo new;
3244 memset(&new, 0, sizeof(new));
3245
3246 new.si_signo = from->si_signo;
3247 new.si_errno = from->si_errno;
3248 new.si_code = from->si_code;
3249 switch(siginfo_layout(from->si_signo, from->si_code)) {
3250 case SIL_KILL:
3251 new.si_pid = from->si_pid;
3252 new.si_uid = from->si_uid;
3253 break;
3254 case SIL_TIMER:
3255 new.si_tid = from->si_tid;
3256 new.si_overrun = from->si_overrun;
3257 new.si_int = from->si_int;
3258 break;
3259 case SIL_POLL:
3260 new.si_band = from->si_band;
3261 new.si_fd = from->si_fd;
3262 break;
3263 case SIL_FAULT:
3264 new.si_addr = ptr_to_compat(from->si_addr);
3265#ifdef __ARCH_SI_TRAPNO
3266 new.si_trapno = from->si_trapno;
3267#endif
3268 break;
3269 case SIL_FAULT_MCEERR:
3270 new.si_addr = ptr_to_compat(from->si_addr);
3271#ifdef __ARCH_SI_TRAPNO
3272 new.si_trapno = from->si_trapno;
3273#endif
3274 new.si_addr_lsb = from->si_addr_lsb;
3275 break;
3276 case SIL_FAULT_BNDERR:
3277 new.si_addr = ptr_to_compat(from->si_addr);
3278#ifdef __ARCH_SI_TRAPNO
3279 new.si_trapno = from->si_trapno;
3280#endif
3281 new.si_lower = ptr_to_compat(from->si_lower);
3282 new.si_upper = ptr_to_compat(from->si_upper);
3283 break;
3284 case SIL_FAULT_PKUERR:
3285 new.si_addr = ptr_to_compat(from->si_addr);
3286#ifdef __ARCH_SI_TRAPNO
3287 new.si_trapno = from->si_trapno;
3288#endif
3289 new.si_pkey = from->si_pkey;
3290 break;
3291 case SIL_CHLD:
3292 new.si_pid = from->si_pid;
3293 new.si_uid = from->si_uid;
3294 new.si_status = from->si_status;
3295#ifdef CONFIG_X86_X32_ABI
3296 if (x32_ABI) {
3297 new._sifields._sigchld_x32._utime = from->si_utime;
3298 new._sifields._sigchld_x32._stime = from->si_stime;
3299 } else
3300#endif
3301 {
3302 new.si_utime = from->si_utime;
3303 new.si_stime = from->si_stime;
3304 }
3305 break;
3306 case SIL_RT:
3307 new.si_pid = from->si_pid;
3308 new.si_uid = from->si_uid;
3309 new.si_int = from->si_int;
3310 break;
3311 case SIL_SYS:
3312 new.si_call_addr = ptr_to_compat(from->si_call_addr);
3313 new.si_syscall = from->si_syscall;
3314 new.si_arch = from->si_arch;
3315 break;
3316 }
3317
3318 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3319 return -EFAULT;
3320
3321 return 0;
3322}
3323
3324static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3325 const struct compat_siginfo *from)
3326{
3327 clear_siginfo(to);
3328 to->si_signo = from->si_signo;
3329 to->si_errno = from->si_errno;
3330 to->si_code = from->si_code;
3331 switch(siginfo_layout(from->si_signo, from->si_code)) {
3332 case SIL_KILL:
3333 to->si_pid = from->si_pid;
3334 to->si_uid = from->si_uid;
3335 break;
3336 case SIL_TIMER:
3337 to->si_tid = from->si_tid;
3338 to->si_overrun = from->si_overrun;
3339 to->si_int = from->si_int;
3340 break;
3341 case SIL_POLL:
3342 to->si_band = from->si_band;
3343 to->si_fd = from->si_fd;
3344 break;
3345 case SIL_FAULT:
3346 to->si_addr = compat_ptr(from->si_addr);
3347#ifdef __ARCH_SI_TRAPNO
3348 to->si_trapno = from->si_trapno;
3349#endif
3350 break;
3351 case SIL_FAULT_MCEERR:
3352 to->si_addr = compat_ptr(from->si_addr);
3353#ifdef __ARCH_SI_TRAPNO
3354 to->si_trapno = from->si_trapno;
3355#endif
3356 to->si_addr_lsb = from->si_addr_lsb;
3357 break;
3358 case SIL_FAULT_BNDERR:
3359 to->si_addr = compat_ptr(from->si_addr);
3360#ifdef __ARCH_SI_TRAPNO
3361 to->si_trapno = from->si_trapno;
3362#endif
3363 to->si_lower = compat_ptr(from->si_lower);
3364 to->si_upper = compat_ptr(from->si_upper);
3365 break;
3366 case SIL_FAULT_PKUERR:
3367 to->si_addr = compat_ptr(from->si_addr);
3368#ifdef __ARCH_SI_TRAPNO
3369 to->si_trapno = from->si_trapno;
3370#endif
3371 to->si_pkey = from->si_pkey;
3372 break;
3373 case SIL_CHLD:
3374 to->si_pid = from->si_pid;
3375 to->si_uid = from->si_uid;
3376 to->si_status = from->si_status;
3377#ifdef CONFIG_X86_X32_ABI
3378 if (in_x32_syscall()) {
3379 to->si_utime = from->_sifields._sigchld_x32._utime;
3380 to->si_stime = from->_sifields._sigchld_x32._stime;
3381 } else
3382#endif
3383 {
3384 to->si_utime = from->si_utime;
3385 to->si_stime = from->si_stime;
3386 }
3387 break;
3388 case SIL_RT:
3389 to->si_pid = from->si_pid;
3390 to->si_uid = from->si_uid;
3391 to->si_int = from->si_int;
3392 break;
3393 case SIL_SYS:
3394 to->si_call_addr = compat_ptr(from->si_call_addr);
3395 to->si_syscall = from->si_syscall;
3396 to->si_arch = from->si_arch;
3397 break;
3398 }
3399 return 0;
3400}
3401
3402static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3403 const struct compat_siginfo __user *ufrom)
3404{
3405 struct compat_siginfo from;
3406
3407 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3408 return -EFAULT;
3409
3410 from.si_signo = signo;
3411 return post_copy_siginfo_from_user32(to, &from);
3412}
3413
3414int copy_siginfo_from_user32(struct kernel_siginfo *to,
3415 const struct compat_siginfo __user *ufrom)
3416{
3417 struct compat_siginfo from;
3418
3419 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3420 return -EFAULT;
3421
3422 return post_copy_siginfo_from_user32(to, &from);
3423}
3424#endif /* CONFIG_COMPAT */
3425
3426/**
3427 * do_sigtimedwait - wait for queued signals specified in @which
3428 * @which: queued signals to wait for
3429 * @info: if non-null, the signal's siginfo is returned here
3430 * @ts: upper bound on process time suspension
3431 */
3432static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3433 const struct timespec64 *ts)
3434{
3435 ktime_t *to = NULL, timeout = KTIME_MAX;
3436 struct task_struct *tsk = current;
3437 sigset_t mask = *which;
3438 int sig, ret = 0;
3439
3440 if (ts) {
3441 if (!timespec64_valid(ts))
3442 return -EINVAL;
3443 timeout = timespec64_to_ktime(*ts);
3444 to = &timeout;
3445 }
3446
3447 /*
3448 * Invert the set of allowed signals to get those we want to block.
3449 */
3450 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3451 signotset(&mask);
3452
3453 spin_lock_irq(&tsk->sighand->siglock);
3454 sig = dequeue_signal(tsk, &mask, info);
3455 if (!sig && timeout) {
3456 /*
3457 * None ready, temporarily unblock those we're interested
3458 * while we are sleeping in so that we'll be awakened when
3459 * they arrive. Unblocking is always fine, we can avoid
3460 * set_current_blocked().
3461 */
3462 tsk->real_blocked = tsk->blocked;
3463 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3464 recalc_sigpending();
3465 spin_unlock_irq(&tsk->sighand->siglock);
3466
3467 __set_current_state(TASK_INTERRUPTIBLE);
3468 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3469 HRTIMER_MODE_REL);
3470 spin_lock_irq(&tsk->sighand->siglock);
3471 __set_task_blocked(tsk, &tsk->real_blocked);
3472 sigemptyset(&tsk->real_blocked);
3473 sig = dequeue_signal(tsk, &mask, info);
3474 }
3475 spin_unlock_irq(&tsk->sighand->siglock);
3476
3477 if (sig)
3478 return sig;
3479 return ret ? -EINTR : -EAGAIN;
3480}
3481
3482/**
3483 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3484 * in @uthese
3485 * @uthese: queued signals to wait for
3486 * @uinfo: if non-null, the signal's siginfo is returned here
3487 * @uts: upper bound on process time suspension
3488 * @sigsetsize: size of sigset_t type
3489 */
3490SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3491 siginfo_t __user *, uinfo,
3492 const struct __kernel_timespec __user *, uts,
3493 size_t, sigsetsize)
3494{
3495 sigset_t these;
3496 struct timespec64 ts;
3497 kernel_siginfo_t info;
3498 int ret;
3499
3500 /* XXX: Don't preclude handling different sized sigset_t's. */
3501 if (sigsetsize != sizeof(sigset_t))
3502 return -EINVAL;
3503
3504 if (copy_from_user(&these, uthese, sizeof(these)))
3505 return -EFAULT;
3506
3507 if (uts) {
3508 if (get_timespec64(&ts, uts))
3509 return -EFAULT;
3510 }
3511
3512 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3513
3514 if (ret > 0 && uinfo) {
3515 if (copy_siginfo_to_user(uinfo, &info))
3516 ret = -EFAULT;
3517 }
3518
3519 return ret;
3520}
3521
3522#ifdef CONFIG_COMPAT_32BIT_TIME
3523SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3524 siginfo_t __user *, uinfo,
3525 const struct old_timespec32 __user *, uts,
3526 size_t, sigsetsize)
3527{
3528 sigset_t these;
3529 struct timespec64 ts;
3530 kernel_siginfo_t info;
3531 int ret;
3532
3533 if (sigsetsize != sizeof(sigset_t))
3534 return -EINVAL;
3535
3536 if (copy_from_user(&these, uthese, sizeof(these)))
3537 return -EFAULT;
3538
3539 if (uts) {
3540 if (get_old_timespec32(&ts, uts))
3541 return -EFAULT;
3542 }
3543
3544 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3545
3546 if (ret > 0 && uinfo) {
3547 if (copy_siginfo_to_user(uinfo, &info))
3548 ret = -EFAULT;
3549 }
3550
3551 return ret;
3552}
3553#endif
3554
3555#ifdef CONFIG_COMPAT
3556COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3557 struct compat_siginfo __user *, uinfo,
3558 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3559{
3560 sigset_t s;
3561 struct timespec64 t;
3562 kernel_siginfo_t info;
3563 long ret;
3564
3565 if (sigsetsize != sizeof(sigset_t))
3566 return -EINVAL;
3567
3568 if (get_compat_sigset(&s, uthese))
3569 return -EFAULT;
3570
3571 if (uts) {
3572 if (get_timespec64(&t, uts))
3573 return -EFAULT;
3574 }
3575
3576 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3577
3578 if (ret > 0 && uinfo) {
3579 if (copy_siginfo_to_user32(uinfo, &info))
3580 ret = -EFAULT;
3581 }
3582
3583 return ret;
3584}
3585
3586#ifdef CONFIG_COMPAT_32BIT_TIME
3587COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3588 struct compat_siginfo __user *, uinfo,
3589 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3590{
3591 sigset_t s;
3592 struct timespec64 t;
3593 kernel_siginfo_t info;
3594 long ret;
3595
3596 if (sigsetsize != sizeof(sigset_t))
3597 return -EINVAL;
3598
3599 if (get_compat_sigset(&s, uthese))
3600 return -EFAULT;
3601
3602 if (uts) {
3603 if (get_old_timespec32(&t, uts))
3604 return -EFAULT;
3605 }
3606
3607 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3608
3609 if (ret > 0 && uinfo) {
3610 if (copy_siginfo_to_user32(uinfo, &info))
3611 ret = -EFAULT;
3612 }
3613
3614 return ret;
3615}
3616#endif
3617#endif
3618
3619static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3620{
3621 clear_siginfo(info);
3622 info->si_signo = sig;
3623 info->si_errno = 0;
3624 info->si_code = SI_USER;
3625 info->si_pid = task_tgid_vnr(current);
3626 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3627}
3628
3629/**
3630 * sys_kill - send a signal to a process
3631 * @pid: the PID of the process
3632 * @sig: signal to be sent
3633 */
3634SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3635{
3636 struct kernel_siginfo info;
3637
3638 prepare_kill_siginfo(sig, &info);
3639
3640 return kill_something_info(sig, &info, pid);
3641}
3642
3643/*
3644 * Verify that the signaler and signalee either are in the same pid namespace
3645 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3646 * namespace.
3647 */
3648static bool access_pidfd_pidns(struct pid *pid)
3649{
3650 struct pid_namespace *active = task_active_pid_ns(current);
3651 struct pid_namespace *p = ns_of_pid(pid);
3652
3653 for (;;) {
3654 if (!p)
3655 return false;
3656 if (p == active)
3657 break;
3658 p = p->parent;
3659 }
3660
3661 return true;
3662}
3663
3664static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo, siginfo_t *info)
3665{
3666#ifdef CONFIG_COMPAT
3667 /*
3668 * Avoid hooking up compat syscalls and instead handle necessary
3669 * conversions here. Note, this is a stop-gap measure and should not be
3670 * considered a generic solution.
3671 */
3672 if (in_compat_syscall())
3673 return copy_siginfo_from_user32(
3674 kinfo, (struct compat_siginfo __user *)info);
3675#endif
3676 return copy_siginfo_from_user(kinfo, info);
3677}
3678
3679static struct pid *pidfd_to_pid(const struct file *file)
3680{
3681 struct pid *pid;
3682
3683 pid = pidfd_pid(file);
3684 if (!IS_ERR(pid))
3685 return pid;
3686
3687 return tgid_pidfd_to_pid(file);
3688}
3689
3690/**
3691 * sys_pidfd_send_signal - Signal a process through a pidfd
3692 * @pidfd: file descriptor of the process
3693 * @sig: signal to send
3694 * @info: signal info
3695 * @flags: future flags
3696 *
3697 * The syscall currently only signals via PIDTYPE_PID which covers
3698 * kill(<positive-pid>, <signal>. It does not signal threads or process
3699 * groups.
3700 * In order to extend the syscall to threads and process groups the @flags
3701 * argument should be used. In essence, the @flags argument will determine
3702 * what is signaled and not the file descriptor itself. Put in other words,
3703 * grouping is a property of the flags argument not a property of the file
3704 * descriptor.
3705 *
3706 * Return: 0 on success, negative errno on failure
3707 */
3708SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3709 siginfo_t __user *, info, unsigned int, flags)
3710{
3711 int ret;
3712 struct fd f;
3713 struct pid *pid;
3714 kernel_siginfo_t kinfo;
3715
3716 /* Enforce flags be set to 0 until we add an extension. */
3717 if (flags)
3718 return -EINVAL;
3719
3720 f = fdget(pidfd);
3721 if (!f.file)
3722 return -EBADF;
3723
3724 /* Is this a pidfd? */
3725 pid = pidfd_to_pid(f.file);
3726 if (IS_ERR(pid)) {
3727 ret = PTR_ERR(pid);
3728 goto err;
3729 }
3730
3731 ret = -EINVAL;
3732 if (!access_pidfd_pidns(pid))
3733 goto err;
3734
3735 if (info) {
3736 ret = copy_siginfo_from_user_any(&kinfo, info);
3737 if (unlikely(ret))
3738 goto err;
3739
3740 ret = -EINVAL;
3741 if (unlikely(sig != kinfo.si_signo))
3742 goto err;
3743
3744 /* Only allow sending arbitrary signals to yourself. */
3745 ret = -EPERM;
3746 if ((task_pid(current) != pid) &&
3747 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3748 goto err;
3749 } else {
3750 prepare_kill_siginfo(sig, &kinfo);
3751 }
3752
3753 ret = kill_pid_info(sig, &kinfo, pid);
3754
3755err:
3756 fdput(f);
3757 return ret;
3758}
3759
3760static int
3761do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3762{
3763 struct task_struct *p;
3764 int error = -ESRCH;
3765
3766 rcu_read_lock();
3767 p = find_task_by_vpid(pid);
3768 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3769 error = check_kill_permission(sig, info, p);
3770 /*
3771 * The null signal is a permissions and process existence
3772 * probe. No signal is actually delivered.
3773 */
3774 if (!error && sig) {
3775 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3776 /*
3777 * If lock_task_sighand() failed we pretend the task
3778 * dies after receiving the signal. The window is tiny,
3779 * and the signal is private anyway.
3780 */
3781 if (unlikely(error == -ESRCH))
3782 error = 0;
3783 }
3784 }
3785 rcu_read_unlock();
3786
3787 return error;
3788}
3789
3790static int do_tkill(pid_t tgid, pid_t pid, int sig)
3791{
3792 struct kernel_siginfo info;
3793
3794 clear_siginfo(&info);
3795 info.si_signo = sig;
3796 info.si_errno = 0;
3797 info.si_code = SI_TKILL;
3798 info.si_pid = task_tgid_vnr(current);
3799 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3800
3801 return do_send_specific(tgid, pid, sig, &info);
3802}
3803
3804/**
3805 * sys_tgkill - send signal to one specific thread
3806 * @tgid: the thread group ID of the thread
3807 * @pid: the PID of the thread
3808 * @sig: signal to be sent
3809 *
3810 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3811 * exists but it's not belonging to the target process anymore. This
3812 * method solves the problem of threads exiting and PIDs getting reused.
3813 */
3814SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3815{
3816 /* This is only valid for single tasks */
3817 if (pid <= 0 || tgid <= 0)
3818 return -EINVAL;
3819
3820 return do_tkill(tgid, pid, sig);
3821}
3822
3823/**
3824 * sys_tkill - send signal to one specific task
3825 * @pid: the PID of the task
3826 * @sig: signal to be sent
3827 *
3828 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3829 */
3830SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3831{
3832 /* This is only valid for single tasks */
3833 if (pid <= 0)
3834 return -EINVAL;
3835
3836 return do_tkill(0, pid, sig);
3837}
3838
3839static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3840{
3841 /* Not even root can pretend to send signals from the kernel.
3842 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3843 */
3844 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3845 (task_pid_vnr(current) != pid))
3846 return -EPERM;
3847
3848 /* POSIX.1b doesn't mention process groups. */
3849 return kill_proc_info(sig, info, pid);
3850}
3851
3852/**
3853 * sys_rt_sigqueueinfo - send signal information to a signal
3854 * @pid: the PID of the thread
3855 * @sig: signal to be sent
3856 * @uinfo: signal info to be sent
3857 */
3858SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3859 siginfo_t __user *, uinfo)
3860{
3861 kernel_siginfo_t info;
3862 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3863 if (unlikely(ret))
3864 return ret;
3865 return do_rt_sigqueueinfo(pid, sig, &info);
3866}
3867
3868#ifdef CONFIG_COMPAT
3869COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3870 compat_pid_t, pid,
3871 int, sig,
3872 struct compat_siginfo __user *, uinfo)
3873{
3874 kernel_siginfo_t info;
3875 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3876 if (unlikely(ret))
3877 return ret;
3878 return do_rt_sigqueueinfo(pid, sig, &info);
3879}
3880#endif
3881
3882static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
3883{
3884 /* This is only valid for single tasks */
3885 if (pid <= 0 || tgid <= 0)
3886 return -EINVAL;
3887
3888 /* Not even root can pretend to send signals from the kernel.
3889 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3890 */
3891 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3892 (task_pid_vnr(current) != pid))
3893 return -EPERM;
3894
3895 return do_send_specific(tgid, pid, sig, info);
3896}
3897
3898SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3899 siginfo_t __user *, uinfo)
3900{
3901 kernel_siginfo_t info;
3902 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3903 if (unlikely(ret))
3904 return ret;
3905 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3906}
3907
3908#ifdef CONFIG_COMPAT
3909COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3910 compat_pid_t, tgid,
3911 compat_pid_t, pid,
3912 int, sig,
3913 struct compat_siginfo __user *, uinfo)
3914{
3915 kernel_siginfo_t info;
3916 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3917 if (unlikely(ret))
3918 return ret;
3919 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3920}
3921#endif
3922
3923/*
3924 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3925 */
3926void kernel_sigaction(int sig, __sighandler_t action)
3927{
3928 spin_lock_irq(¤t->sighand->siglock);
3929 current->sighand->action[sig - 1].sa.sa_handler = action;
3930 if (action == SIG_IGN) {
3931 sigset_t mask;
3932
3933 sigemptyset(&mask);
3934 sigaddset(&mask, sig);
3935
3936 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3937 flush_sigqueue_mask(&mask, ¤t->pending);
3938 recalc_sigpending();
3939 }
3940 spin_unlock_irq(¤t->sighand->siglock);
3941}
3942EXPORT_SYMBOL(kernel_sigaction);
3943
3944void __weak sigaction_compat_abi(struct k_sigaction *act,
3945 struct k_sigaction *oact)
3946{
3947}
3948
3949int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3950{
3951 struct task_struct *p = current, *t;
3952 struct k_sigaction *k;
3953 sigset_t mask;
3954
3955 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3956 return -EINVAL;
3957
3958 k = &p->sighand->action[sig-1];
3959
3960 spin_lock_irq(&p->sighand->siglock);
3961 if (oact)
3962 *oact = *k;
3963
3964 sigaction_compat_abi(act, oact);
3965
3966 if (act) {
3967 sigdelsetmask(&act->sa.sa_mask,
3968 sigmask(SIGKILL) | sigmask(SIGSTOP));
3969 *k = *act;
3970 /*
3971 * POSIX 3.3.1.3:
3972 * "Setting a signal action to SIG_IGN for a signal that is
3973 * pending shall cause the pending signal to be discarded,
3974 * whether or not it is blocked."
3975 *
3976 * "Setting a signal action to SIG_DFL for a signal that is
3977 * pending and whose default action is to ignore the signal
3978 * (for example, SIGCHLD), shall cause the pending signal to
3979 * be discarded, whether or not it is blocked"
3980 */
3981 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3982 sigemptyset(&mask);
3983 sigaddset(&mask, sig);
3984 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3985 for_each_thread(p, t)
3986 flush_sigqueue_mask(&mask, &t->pending);
3987 }
3988 }
3989
3990 spin_unlock_irq(&p->sighand->siglock);
3991 return 0;
3992}
3993
3994static int
3995do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
3996 size_t min_ss_size)
3997{
3998 struct task_struct *t = current;
3999
4000 if (oss) {
4001 memset(oss, 0, sizeof(stack_t));
4002 oss->ss_sp = (void __user *) t->sas_ss_sp;
4003 oss->ss_size = t->sas_ss_size;
4004 oss->ss_flags = sas_ss_flags(sp) |
4005 (current->sas_ss_flags & SS_FLAG_BITS);
4006 }
4007
4008 if (ss) {
4009 void __user *ss_sp = ss->ss_sp;
4010 size_t ss_size = ss->ss_size;
4011 unsigned ss_flags = ss->ss_flags;
4012 int ss_mode;
4013
4014 if (unlikely(on_sig_stack(sp)))
4015 return -EPERM;
4016
4017 ss_mode = ss_flags & ~SS_FLAG_BITS;
4018 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4019 ss_mode != 0))
4020 return -EINVAL;
4021
4022 if (ss_mode == SS_DISABLE) {
4023 ss_size = 0;
4024 ss_sp = NULL;
4025 } else {
4026 if (unlikely(ss_size < min_ss_size))
4027 return -ENOMEM;
4028 }
4029
4030 t->sas_ss_sp = (unsigned long) ss_sp;
4031 t->sas_ss_size = ss_size;
4032 t->sas_ss_flags = ss_flags;
4033 }
4034 return 0;
4035}
4036
4037SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4038{
4039 stack_t new, old;
4040 int err;
4041 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4042 return -EFAULT;
4043 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4044 current_user_stack_pointer(),
4045 MINSIGSTKSZ);
4046 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4047 err = -EFAULT;
4048 return err;
4049}
4050
4051int restore_altstack(const stack_t __user *uss)
4052{
4053 stack_t new;
4054 if (copy_from_user(&new, uss, sizeof(stack_t)))
4055 return -EFAULT;
4056 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4057 MINSIGSTKSZ);
4058 /* squash all but EFAULT for now */
4059 return 0;
4060}
4061
4062int __save_altstack(stack_t __user *uss, unsigned long sp)
4063{
4064 struct task_struct *t = current;
4065 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4066 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4067 __put_user(t->sas_ss_size, &uss->ss_size);
4068 if (err)
4069 return err;
4070 if (t->sas_ss_flags & SS_AUTODISARM)
4071 sas_ss_reset(t);
4072 return 0;
4073}
4074
4075#ifdef CONFIG_COMPAT
4076static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4077 compat_stack_t __user *uoss_ptr)
4078{
4079 stack_t uss, uoss;
4080 int ret;
4081
4082 if (uss_ptr) {
4083 compat_stack_t uss32;
4084 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4085 return -EFAULT;
4086 uss.ss_sp = compat_ptr(uss32.ss_sp);
4087 uss.ss_flags = uss32.ss_flags;
4088 uss.ss_size = uss32.ss_size;
4089 }
4090 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4091 compat_user_stack_pointer(),
4092 COMPAT_MINSIGSTKSZ);
4093 if (ret >= 0 && uoss_ptr) {
4094 compat_stack_t old;
4095 memset(&old, 0, sizeof(old));
4096 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4097 old.ss_flags = uoss.ss_flags;
4098 old.ss_size = uoss.ss_size;
4099 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4100 ret = -EFAULT;
4101 }
4102 return ret;
4103}
4104
4105COMPAT_SYSCALL_DEFINE2(sigaltstack,
4106 const compat_stack_t __user *, uss_ptr,
4107 compat_stack_t __user *, uoss_ptr)
4108{
4109 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4110}
4111
4112int compat_restore_altstack(const compat_stack_t __user *uss)
4113{
4114 int err = do_compat_sigaltstack(uss, NULL);
4115 /* squash all but -EFAULT for now */
4116 return err == -EFAULT ? err : 0;
4117}
4118
4119int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4120{
4121 int err;
4122 struct task_struct *t = current;
4123 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4124 &uss->ss_sp) |
4125 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4126 __put_user(t->sas_ss_size, &uss->ss_size);
4127 if (err)
4128 return err;
4129 if (t->sas_ss_flags & SS_AUTODISARM)
4130 sas_ss_reset(t);
4131 return 0;
4132}
4133#endif
4134
4135#ifdef __ARCH_WANT_SYS_SIGPENDING
4136
4137/**
4138 * sys_sigpending - examine pending signals
4139 * @uset: where mask of pending signal is returned
4140 */
4141SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4142{
4143 sigset_t set;
4144
4145 if (sizeof(old_sigset_t) > sizeof(*uset))
4146 return -EINVAL;
4147
4148 do_sigpending(&set);
4149
4150 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4151 return -EFAULT;
4152
4153 return 0;
4154}
4155
4156#ifdef CONFIG_COMPAT
4157COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4158{
4159 sigset_t set;
4160
4161 do_sigpending(&set);
4162
4163 return put_user(set.sig[0], set32);
4164}
4165#endif
4166
4167#endif
4168
4169#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4170/**
4171 * sys_sigprocmask - examine and change blocked signals
4172 * @how: whether to add, remove, or set signals
4173 * @nset: signals to add or remove (if non-null)
4174 * @oset: previous value of signal mask if non-null
4175 *
4176 * Some platforms have their own version with special arguments;
4177 * others support only sys_rt_sigprocmask.
4178 */
4179
4180SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4181 old_sigset_t __user *, oset)
4182{
4183 old_sigset_t old_set, new_set;
4184 sigset_t new_blocked;
4185
4186 old_set = current->blocked.sig[0];
4187
4188 if (nset) {
4189 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4190 return -EFAULT;
4191
4192 new_blocked = current->blocked;
4193
4194 switch (how) {
4195 case SIG_BLOCK:
4196 sigaddsetmask(&new_blocked, new_set);
4197 break;
4198 case SIG_UNBLOCK:
4199 sigdelsetmask(&new_blocked, new_set);
4200 break;
4201 case SIG_SETMASK:
4202 new_blocked.sig[0] = new_set;
4203 break;
4204 default:
4205 return -EINVAL;
4206 }
4207
4208 set_current_blocked(&new_blocked);
4209 }
4210
4211 if (oset) {
4212 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4213 return -EFAULT;
4214 }
4215
4216 return 0;
4217}
4218#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4219
4220#ifndef CONFIG_ODD_RT_SIGACTION
4221/**
4222 * sys_rt_sigaction - alter an action taken by a process
4223 * @sig: signal to be sent
4224 * @act: new sigaction
4225 * @oact: used to save the previous sigaction
4226 * @sigsetsize: size of sigset_t type
4227 */
4228SYSCALL_DEFINE4(rt_sigaction, int, sig,
4229 const struct sigaction __user *, act,
4230 struct sigaction __user *, oact,
4231 size_t, sigsetsize)
4232{
4233 struct k_sigaction new_sa, old_sa;
4234 int ret;
4235
4236 /* XXX: Don't preclude handling different sized sigset_t's. */
4237 if (sigsetsize != sizeof(sigset_t))
4238 return -EINVAL;
4239
4240 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4241 return -EFAULT;
4242
4243 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4244 if (ret)
4245 return ret;
4246
4247 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4248 return -EFAULT;
4249
4250 return 0;
4251}
4252#ifdef CONFIG_COMPAT
4253COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4254 const struct compat_sigaction __user *, act,
4255 struct compat_sigaction __user *, oact,
4256 compat_size_t, sigsetsize)
4257{
4258 struct k_sigaction new_ka, old_ka;
4259#ifdef __ARCH_HAS_SA_RESTORER
4260 compat_uptr_t restorer;
4261#endif
4262 int ret;
4263
4264 /* XXX: Don't preclude handling different sized sigset_t's. */
4265 if (sigsetsize != sizeof(compat_sigset_t))
4266 return -EINVAL;
4267
4268 if (act) {
4269 compat_uptr_t handler;
4270 ret = get_user(handler, &act->sa_handler);
4271 new_ka.sa.sa_handler = compat_ptr(handler);
4272#ifdef __ARCH_HAS_SA_RESTORER
4273 ret |= get_user(restorer, &act->sa_restorer);
4274 new_ka.sa.sa_restorer = compat_ptr(restorer);
4275#endif
4276 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4277 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4278 if (ret)
4279 return -EFAULT;
4280 }
4281
4282 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4283 if (!ret && oact) {
4284 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4285 &oact->sa_handler);
4286 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4287 sizeof(oact->sa_mask));
4288 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4289#ifdef __ARCH_HAS_SA_RESTORER
4290 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4291 &oact->sa_restorer);
4292#endif
4293 }
4294 return ret;
4295}
4296#endif
4297#endif /* !CONFIG_ODD_RT_SIGACTION */
4298
4299#ifdef CONFIG_OLD_SIGACTION
4300SYSCALL_DEFINE3(sigaction, int, sig,
4301 const struct old_sigaction __user *, act,
4302 struct old_sigaction __user *, oact)
4303{
4304 struct k_sigaction new_ka, old_ka;
4305 int ret;
4306
4307 if (act) {
4308 old_sigset_t mask;
4309 if (!access_ok(act, sizeof(*act)) ||
4310 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4311 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4312 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4313 __get_user(mask, &act->sa_mask))
4314 return -EFAULT;
4315#ifdef __ARCH_HAS_KA_RESTORER
4316 new_ka.ka_restorer = NULL;
4317#endif
4318 siginitset(&new_ka.sa.sa_mask, mask);
4319 }
4320
4321 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4322
4323 if (!ret && oact) {
4324 if (!access_ok(oact, sizeof(*oact)) ||
4325 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4326 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4327 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4328 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4329 return -EFAULT;
4330 }
4331
4332 return ret;
4333}
4334#endif
4335#ifdef CONFIG_COMPAT_OLD_SIGACTION
4336COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4337 const struct compat_old_sigaction __user *, act,
4338 struct compat_old_sigaction __user *, oact)
4339{
4340 struct k_sigaction new_ka, old_ka;
4341 int ret;
4342 compat_old_sigset_t mask;
4343 compat_uptr_t handler, restorer;
4344
4345 if (act) {
4346 if (!access_ok(act, sizeof(*act)) ||
4347 __get_user(handler, &act->sa_handler) ||
4348 __get_user(restorer, &act->sa_restorer) ||
4349 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4350 __get_user(mask, &act->sa_mask))
4351 return -EFAULT;
4352
4353#ifdef __ARCH_HAS_KA_RESTORER
4354 new_ka.ka_restorer = NULL;
4355#endif
4356 new_ka.sa.sa_handler = compat_ptr(handler);
4357 new_ka.sa.sa_restorer = compat_ptr(restorer);
4358 siginitset(&new_ka.sa.sa_mask, mask);
4359 }
4360
4361 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4362
4363 if (!ret && oact) {
4364 if (!access_ok(oact, sizeof(*oact)) ||
4365 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4366 &oact->sa_handler) ||
4367 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4368 &oact->sa_restorer) ||
4369 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4370 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4371 return -EFAULT;
4372 }
4373 return ret;
4374}
4375#endif
4376
4377#ifdef CONFIG_SGETMASK_SYSCALL
4378
4379/*
4380 * For backwards compatibility. Functionality superseded by sigprocmask.
4381 */
4382SYSCALL_DEFINE0(sgetmask)
4383{
4384 /* SMP safe */
4385 return current->blocked.sig[0];
4386}
4387
4388SYSCALL_DEFINE1(ssetmask, int, newmask)
4389{
4390 int old = current->blocked.sig[0];
4391 sigset_t newset;
4392
4393 siginitset(&newset, newmask);
4394 set_current_blocked(&newset);
4395
4396 return old;
4397}
4398#endif /* CONFIG_SGETMASK_SYSCALL */
4399
4400#ifdef __ARCH_WANT_SYS_SIGNAL
4401/*
4402 * For backwards compatibility. Functionality superseded by sigaction.
4403 */
4404SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4405{
4406 struct k_sigaction new_sa, old_sa;
4407 int ret;
4408
4409 new_sa.sa.sa_handler = handler;
4410 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4411 sigemptyset(&new_sa.sa.sa_mask);
4412
4413 ret = do_sigaction(sig, &new_sa, &old_sa);
4414
4415 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4416}
4417#endif /* __ARCH_WANT_SYS_SIGNAL */
4418
4419#ifdef __ARCH_WANT_SYS_PAUSE
4420
4421SYSCALL_DEFINE0(pause)
4422{
4423 while (!signal_pending(current)) {
4424 __set_current_state(TASK_INTERRUPTIBLE);
4425 schedule();
4426 }
4427 return -ERESTARTNOHAND;
4428}
4429
4430#endif
4431
4432static int sigsuspend(sigset_t *set)
4433{
4434 current->saved_sigmask = current->blocked;
4435 set_current_blocked(set);
4436
4437 while (!signal_pending(current)) {
4438 __set_current_state(TASK_INTERRUPTIBLE);
4439 schedule();
4440 }
4441 set_restore_sigmask();
4442 return -ERESTARTNOHAND;
4443}
4444
4445/**
4446 * sys_rt_sigsuspend - replace the signal mask for a value with the
4447 * @unewset value until a signal is received
4448 * @unewset: new signal mask value
4449 * @sigsetsize: size of sigset_t type
4450 */
4451SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4452{
4453 sigset_t newset;
4454
4455 /* XXX: Don't preclude handling different sized sigset_t's. */
4456 if (sigsetsize != sizeof(sigset_t))
4457 return -EINVAL;
4458
4459 if (copy_from_user(&newset, unewset, sizeof(newset)))
4460 return -EFAULT;
4461 return sigsuspend(&newset);
4462}
4463
4464#ifdef CONFIG_COMPAT
4465COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4466{
4467 sigset_t newset;
4468
4469 /* XXX: Don't preclude handling different sized sigset_t's. */
4470 if (sigsetsize != sizeof(sigset_t))
4471 return -EINVAL;
4472
4473 if (get_compat_sigset(&newset, unewset))
4474 return -EFAULT;
4475 return sigsuspend(&newset);
4476}
4477#endif
4478
4479#ifdef CONFIG_OLD_SIGSUSPEND
4480SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4481{
4482 sigset_t blocked;
4483 siginitset(&blocked, mask);
4484 return sigsuspend(&blocked);
4485}
4486#endif
4487#ifdef CONFIG_OLD_SIGSUSPEND3
4488SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4489{
4490 sigset_t blocked;
4491 siginitset(&blocked, mask);
4492 return sigsuspend(&blocked);
4493}
4494#endif
4495
4496__weak const char *arch_vma_name(struct vm_area_struct *vma)
4497{
4498 return NULL;
4499}
4500
4501static inline void siginfo_buildtime_checks(void)
4502{
4503 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4504
4505 /* Verify the offsets in the two siginfos match */
4506#define CHECK_OFFSET(field) \
4507 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4508
4509 /* kill */
4510 CHECK_OFFSET(si_pid);
4511 CHECK_OFFSET(si_uid);
4512
4513 /* timer */
4514 CHECK_OFFSET(si_tid);
4515 CHECK_OFFSET(si_overrun);
4516 CHECK_OFFSET(si_value);
4517
4518 /* rt */
4519 CHECK_OFFSET(si_pid);
4520 CHECK_OFFSET(si_uid);
4521 CHECK_OFFSET(si_value);
4522
4523 /* sigchld */
4524 CHECK_OFFSET(si_pid);
4525 CHECK_OFFSET(si_uid);
4526 CHECK_OFFSET(si_status);
4527 CHECK_OFFSET(si_utime);
4528 CHECK_OFFSET(si_stime);
4529
4530 /* sigfault */
4531 CHECK_OFFSET(si_addr);
4532 CHECK_OFFSET(si_addr_lsb);
4533 CHECK_OFFSET(si_lower);
4534 CHECK_OFFSET(si_upper);
4535 CHECK_OFFSET(si_pkey);
4536
4537 /* sigpoll */
4538 CHECK_OFFSET(si_band);
4539 CHECK_OFFSET(si_fd);
4540
4541 /* sigsys */
4542 CHECK_OFFSET(si_call_addr);
4543 CHECK_OFFSET(si_syscall);
4544 CHECK_OFFSET(si_arch);
4545#undef CHECK_OFFSET
4546
4547 /* usb asyncio */
4548 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4549 offsetof(struct siginfo, si_addr));
4550 if (sizeof(int) == sizeof(void __user *)) {
4551 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4552 sizeof(void __user *));
4553 } else {
4554 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4555 sizeof_field(struct siginfo, si_uid)) !=
4556 sizeof(void __user *));
4557 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4558 offsetof(struct siginfo, si_uid));
4559 }
4560#ifdef CONFIG_COMPAT
4561 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4562 offsetof(struct compat_siginfo, si_addr));
4563 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4564 sizeof(compat_uptr_t));
4565 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4566 sizeof_field(struct siginfo, si_pid));
4567#endif
4568}
4569
4570void __init signals_init(void)
4571{
4572 siginfo_buildtime_checks();
4573
4574 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4575}
4576
4577#ifdef CONFIG_KGDB_KDB
4578#include <linux/kdb.h>
4579/*
4580 * kdb_send_sig - Allows kdb to send signals without exposing
4581 * signal internals. This function checks if the required locks are
4582 * available before calling the main signal code, to avoid kdb
4583 * deadlocks.
4584 */
4585void kdb_send_sig(struct task_struct *t, int sig)
4586{
4587 static struct task_struct *kdb_prev_t;
4588 int new_t, ret;
4589 if (!spin_trylock(&t->sighand->siglock)) {
4590 kdb_printf("Can't do kill command now.\n"
4591 "The sigmask lock is held somewhere else in "
4592 "kernel, try again later\n");
4593 return;
4594 }
4595 new_t = kdb_prev_t != t;
4596 kdb_prev_t = t;
4597 if (t->state != TASK_RUNNING && new_t) {
4598 spin_unlock(&t->sighand->siglock);
4599 kdb_printf("Process is not RUNNING, sending a signal from "
4600 "kdb risks deadlock\n"
4601 "on the run queue locks. "
4602 "The signal has _not_ been sent.\n"
4603 "Reissue the kill command if you want to risk "
4604 "the deadlock.\n");
4605 return;
4606 }
4607 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4608 spin_unlock(&t->sighand->siglock);
4609 if (ret)
4610 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4611 sig, t->pid);
4612 else
4613 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4614}
4615#endif /* CONFIG_KGDB_KDB */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
12 */
13
14#include <linux/slab.h>
15#include <linux/export.h>
16#include <linux/init.h>
17#include <linux/sched/mm.h>
18#include <linux/sched/user.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/sched/cputime.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/mm.h>
26#include <linux/proc_fs.h>
27#include <linux/tty.h>
28#include <linux/binfmts.h>
29#include <linux/coredump.h>
30#include <linux/security.h>
31#include <linux/syscalls.h>
32#include <linux/ptrace.h>
33#include <linux/signal.h>
34#include <linux/signalfd.h>
35#include <linux/ratelimit.h>
36#include <linux/task_work.h>
37#include <linux/capability.h>
38#include <linux/freezer.h>
39#include <linux/pid_namespace.h>
40#include <linux/nsproxy.h>
41#include <linux/user_namespace.h>
42#include <linux/uprobes.h>
43#include <linux/compat.h>
44#include <linux/cn_proc.h>
45#include <linux/compiler.h>
46#include <linux/posix-timers.h>
47#include <linux/cgroup.h>
48#include <linux/audit.h>
49#include <linux/sysctl.h>
50#include <uapi/linux/pidfd.h>
51
52#define CREATE_TRACE_POINTS
53#include <trace/events/signal.h>
54
55#include <asm/param.h>
56#include <linux/uaccess.h>
57#include <asm/unistd.h>
58#include <asm/siginfo.h>
59#include <asm/cacheflush.h>
60#include <asm/syscall.h> /* for syscall_get_* */
61
62/*
63 * SLAB caches for signal bits.
64 */
65
66static struct kmem_cache *sigqueue_cachep;
67
68int print_fatal_signals __read_mostly;
69
70static void __user *sig_handler(struct task_struct *t, int sig)
71{
72 return t->sighand->action[sig - 1].sa.sa_handler;
73}
74
75static inline bool sig_handler_ignored(void __user *handler, int sig)
76{
77 /* Is it explicitly or implicitly ignored? */
78 return handler == SIG_IGN ||
79 (handler == SIG_DFL && sig_kernel_ignore(sig));
80}
81
82static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
83{
84 void __user *handler;
85
86 handler = sig_handler(t, sig);
87
88 /* SIGKILL and SIGSTOP may not be sent to the global init */
89 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
90 return true;
91
92 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
93 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
94 return true;
95
96 /* Only allow kernel generated signals to this kthread */
97 if (unlikely((t->flags & PF_KTHREAD) &&
98 (handler == SIG_KTHREAD_KERNEL) && !force))
99 return true;
100
101 return sig_handler_ignored(handler, sig);
102}
103
104static bool sig_ignored(struct task_struct *t, int sig, bool force)
105{
106 /*
107 * Blocked signals are never ignored, since the
108 * signal handler may change by the time it is
109 * unblocked.
110 */
111 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
112 return false;
113
114 /*
115 * Tracers may want to know about even ignored signal unless it
116 * is SIGKILL which can't be reported anyway but can be ignored
117 * by SIGNAL_UNKILLABLE task.
118 */
119 if (t->ptrace && sig != SIGKILL)
120 return false;
121
122 return sig_task_ignored(t, sig, force);
123}
124
125/*
126 * Re-calculate pending state from the set of locally pending
127 * signals, globally pending signals, and blocked signals.
128 */
129static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
130{
131 unsigned long ready;
132 long i;
133
134 switch (_NSIG_WORDS) {
135 default:
136 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
137 ready |= signal->sig[i] &~ blocked->sig[i];
138 break;
139
140 case 4: ready = signal->sig[3] &~ blocked->sig[3];
141 ready |= signal->sig[2] &~ blocked->sig[2];
142 ready |= signal->sig[1] &~ blocked->sig[1];
143 ready |= signal->sig[0] &~ blocked->sig[0];
144 break;
145
146 case 2: ready = signal->sig[1] &~ blocked->sig[1];
147 ready |= signal->sig[0] &~ blocked->sig[0];
148 break;
149
150 case 1: ready = signal->sig[0] &~ blocked->sig[0];
151 }
152 return ready != 0;
153}
154
155#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
156
157static bool recalc_sigpending_tsk(struct task_struct *t)
158{
159 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
160 PENDING(&t->pending, &t->blocked) ||
161 PENDING(&t->signal->shared_pending, &t->blocked) ||
162 cgroup_task_frozen(t)) {
163 set_tsk_thread_flag(t, TIF_SIGPENDING);
164 return true;
165 }
166
167 /*
168 * We must never clear the flag in another thread, or in current
169 * when it's possible the current syscall is returning -ERESTART*.
170 * So we don't clear it here, and only callers who know they should do.
171 */
172 return false;
173}
174
175void recalc_sigpending(void)
176{
177 if (!recalc_sigpending_tsk(current) && !freezing(current))
178 clear_thread_flag(TIF_SIGPENDING);
179
180}
181EXPORT_SYMBOL(recalc_sigpending);
182
183void calculate_sigpending(void)
184{
185 /* Have any signals or users of TIF_SIGPENDING been delayed
186 * until after fork?
187 */
188 spin_lock_irq(¤t->sighand->siglock);
189 set_tsk_thread_flag(current, TIF_SIGPENDING);
190 recalc_sigpending();
191 spin_unlock_irq(¤t->sighand->siglock);
192}
193
194/* Given the mask, find the first available signal that should be serviced. */
195
196#define SYNCHRONOUS_MASK \
197 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
198 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
199
200int next_signal(struct sigpending *pending, sigset_t *mask)
201{
202 unsigned long i, *s, *m, x;
203 int sig = 0;
204
205 s = pending->signal.sig;
206 m = mask->sig;
207
208 /*
209 * Handle the first word specially: it contains the
210 * synchronous signals that need to be dequeued first.
211 */
212 x = *s &~ *m;
213 if (x) {
214 if (x & SYNCHRONOUS_MASK)
215 x &= SYNCHRONOUS_MASK;
216 sig = ffz(~x) + 1;
217 return sig;
218 }
219
220 switch (_NSIG_WORDS) {
221 default:
222 for (i = 1; i < _NSIG_WORDS; ++i) {
223 x = *++s &~ *++m;
224 if (!x)
225 continue;
226 sig = ffz(~x) + i*_NSIG_BPW + 1;
227 break;
228 }
229 break;
230
231 case 2:
232 x = s[1] &~ m[1];
233 if (!x)
234 break;
235 sig = ffz(~x) + _NSIG_BPW + 1;
236 break;
237
238 case 1:
239 /* Nothing to do */
240 break;
241 }
242
243 return sig;
244}
245
246static inline void print_dropped_signal(int sig)
247{
248 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
249
250 if (!print_fatal_signals)
251 return;
252
253 if (!__ratelimit(&ratelimit_state))
254 return;
255
256 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
257 current->comm, current->pid, sig);
258}
259
260/**
261 * task_set_jobctl_pending - set jobctl pending bits
262 * @task: target task
263 * @mask: pending bits to set
264 *
265 * Clear @mask from @task->jobctl. @mask must be subset of
266 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
267 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
268 * cleared. If @task is already being killed or exiting, this function
269 * becomes noop.
270 *
271 * CONTEXT:
272 * Must be called with @task->sighand->siglock held.
273 *
274 * RETURNS:
275 * %true if @mask is set, %false if made noop because @task was dying.
276 */
277bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
278{
279 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
280 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
281 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
282
283 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
284 return false;
285
286 if (mask & JOBCTL_STOP_SIGMASK)
287 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
288
289 task->jobctl |= mask;
290 return true;
291}
292
293/**
294 * task_clear_jobctl_trapping - clear jobctl trapping bit
295 * @task: target task
296 *
297 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
298 * Clear it and wake up the ptracer. Note that we don't need any further
299 * locking. @task->siglock guarantees that @task->parent points to the
300 * ptracer.
301 *
302 * CONTEXT:
303 * Must be called with @task->sighand->siglock held.
304 */
305void task_clear_jobctl_trapping(struct task_struct *task)
306{
307 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
308 task->jobctl &= ~JOBCTL_TRAPPING;
309 smp_mb(); /* advised by wake_up_bit() */
310 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
311 }
312}
313
314/**
315 * task_clear_jobctl_pending - clear jobctl pending bits
316 * @task: target task
317 * @mask: pending bits to clear
318 *
319 * Clear @mask from @task->jobctl. @mask must be subset of
320 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
321 * STOP bits are cleared together.
322 *
323 * If clearing of @mask leaves no stop or trap pending, this function calls
324 * task_clear_jobctl_trapping().
325 *
326 * CONTEXT:
327 * Must be called with @task->sighand->siglock held.
328 */
329void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
330{
331 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
332
333 if (mask & JOBCTL_STOP_PENDING)
334 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
335
336 task->jobctl &= ~mask;
337
338 if (!(task->jobctl & JOBCTL_PENDING_MASK))
339 task_clear_jobctl_trapping(task);
340}
341
342/**
343 * task_participate_group_stop - participate in a group stop
344 * @task: task participating in a group stop
345 *
346 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
347 * Group stop states are cleared and the group stop count is consumed if
348 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
349 * stop, the appropriate `SIGNAL_*` flags are set.
350 *
351 * CONTEXT:
352 * Must be called with @task->sighand->siglock held.
353 *
354 * RETURNS:
355 * %true if group stop completion should be notified to the parent, %false
356 * otherwise.
357 */
358static bool task_participate_group_stop(struct task_struct *task)
359{
360 struct signal_struct *sig = task->signal;
361 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
362
363 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
364
365 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
366
367 if (!consume)
368 return false;
369
370 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
371 sig->group_stop_count--;
372
373 /*
374 * Tell the caller to notify completion iff we are entering into a
375 * fresh group stop. Read comment in do_signal_stop() for details.
376 */
377 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
378 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
379 return true;
380 }
381 return false;
382}
383
384void task_join_group_stop(struct task_struct *task)
385{
386 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
387 struct signal_struct *sig = current->signal;
388
389 if (sig->group_stop_count) {
390 sig->group_stop_count++;
391 mask |= JOBCTL_STOP_CONSUME;
392 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
393 return;
394
395 /* Have the new thread join an on-going signal group stop */
396 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
397}
398
399/*
400 * allocate a new signal queue record
401 * - this may be called without locks if and only if t == current, otherwise an
402 * appropriate lock must be held to stop the target task from exiting
403 */
404static struct sigqueue *
405__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
406 int override_rlimit, const unsigned int sigqueue_flags)
407{
408 struct sigqueue *q = NULL;
409 struct ucounts *ucounts;
410 long sigpending;
411
412 /*
413 * Protect access to @t credentials. This can go away when all
414 * callers hold rcu read lock.
415 *
416 * NOTE! A pending signal will hold on to the user refcount,
417 * and we get/put the refcount only when the sigpending count
418 * changes from/to zero.
419 */
420 rcu_read_lock();
421 ucounts = task_ucounts(t);
422 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
423 rcu_read_unlock();
424 if (!sigpending)
425 return NULL;
426
427 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
428 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
429 } else {
430 print_dropped_signal(sig);
431 }
432
433 if (unlikely(q == NULL)) {
434 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
435 } else {
436 INIT_LIST_HEAD(&q->list);
437 q->flags = sigqueue_flags;
438 q->ucounts = ucounts;
439 }
440 return q;
441}
442
443static void __sigqueue_free(struct sigqueue *q)
444{
445 if (q->flags & SIGQUEUE_PREALLOC)
446 return;
447 if (q->ucounts) {
448 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
449 q->ucounts = NULL;
450 }
451 kmem_cache_free(sigqueue_cachep, q);
452}
453
454void flush_sigqueue(struct sigpending *queue)
455{
456 struct sigqueue *q;
457
458 sigemptyset(&queue->signal);
459 while (!list_empty(&queue->list)) {
460 q = list_entry(queue->list.next, struct sigqueue , list);
461 list_del_init(&q->list);
462 __sigqueue_free(q);
463 }
464}
465
466/*
467 * Flush all pending signals for this kthread.
468 */
469void flush_signals(struct task_struct *t)
470{
471 unsigned long flags;
472
473 spin_lock_irqsave(&t->sighand->siglock, flags);
474 clear_tsk_thread_flag(t, TIF_SIGPENDING);
475 flush_sigqueue(&t->pending);
476 flush_sigqueue(&t->signal->shared_pending);
477 spin_unlock_irqrestore(&t->sighand->siglock, flags);
478}
479EXPORT_SYMBOL(flush_signals);
480
481#ifdef CONFIG_POSIX_TIMERS
482static void __flush_itimer_signals(struct sigpending *pending)
483{
484 sigset_t signal, retain;
485 struct sigqueue *q, *n;
486
487 signal = pending->signal;
488 sigemptyset(&retain);
489
490 list_for_each_entry_safe(q, n, &pending->list, list) {
491 int sig = q->info.si_signo;
492
493 if (likely(q->info.si_code != SI_TIMER)) {
494 sigaddset(&retain, sig);
495 } else {
496 sigdelset(&signal, sig);
497 list_del_init(&q->list);
498 __sigqueue_free(q);
499 }
500 }
501
502 sigorsets(&pending->signal, &signal, &retain);
503}
504
505void flush_itimer_signals(void)
506{
507 struct task_struct *tsk = current;
508 unsigned long flags;
509
510 spin_lock_irqsave(&tsk->sighand->siglock, flags);
511 __flush_itimer_signals(&tsk->pending);
512 __flush_itimer_signals(&tsk->signal->shared_pending);
513 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
514}
515#endif
516
517void ignore_signals(struct task_struct *t)
518{
519 int i;
520
521 for (i = 0; i < _NSIG; ++i)
522 t->sighand->action[i].sa.sa_handler = SIG_IGN;
523
524 flush_signals(t);
525}
526
527/*
528 * Flush all handlers for a task.
529 */
530
531void
532flush_signal_handlers(struct task_struct *t, int force_default)
533{
534 int i;
535 struct k_sigaction *ka = &t->sighand->action[0];
536 for (i = _NSIG ; i != 0 ; i--) {
537 if (force_default || ka->sa.sa_handler != SIG_IGN)
538 ka->sa.sa_handler = SIG_DFL;
539 ka->sa.sa_flags = 0;
540#ifdef __ARCH_HAS_SA_RESTORER
541 ka->sa.sa_restorer = NULL;
542#endif
543 sigemptyset(&ka->sa.sa_mask);
544 ka++;
545 }
546}
547
548bool unhandled_signal(struct task_struct *tsk, int sig)
549{
550 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
551 if (is_global_init(tsk))
552 return true;
553
554 if (handler != SIG_IGN && handler != SIG_DFL)
555 return false;
556
557 /* If dying, we handle all new signals by ignoring them */
558 if (fatal_signal_pending(tsk))
559 return false;
560
561 /* if ptraced, let the tracer determine */
562 return !tsk->ptrace;
563}
564
565static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
566 bool *resched_timer)
567{
568 struct sigqueue *q, *first = NULL;
569
570 /*
571 * Collect the siginfo appropriate to this signal. Check if
572 * there is another siginfo for the same signal.
573 */
574 list_for_each_entry(q, &list->list, list) {
575 if (q->info.si_signo == sig) {
576 if (first)
577 goto still_pending;
578 first = q;
579 }
580 }
581
582 sigdelset(&list->signal, sig);
583
584 if (first) {
585still_pending:
586 list_del_init(&first->list);
587 copy_siginfo(info, &first->info);
588
589 *resched_timer =
590 (first->flags & SIGQUEUE_PREALLOC) &&
591 (info->si_code == SI_TIMER) &&
592 (info->si_sys_private);
593
594 __sigqueue_free(first);
595 } else {
596 /*
597 * Ok, it wasn't in the queue. This must be
598 * a fast-pathed signal or we must have been
599 * out of queue space. So zero out the info.
600 */
601 clear_siginfo(info);
602 info->si_signo = sig;
603 info->si_errno = 0;
604 info->si_code = SI_USER;
605 info->si_pid = 0;
606 info->si_uid = 0;
607 }
608}
609
610static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
611 kernel_siginfo_t *info, bool *resched_timer)
612{
613 int sig = next_signal(pending, mask);
614
615 if (sig)
616 collect_signal(sig, pending, info, resched_timer);
617 return sig;
618}
619
620/*
621 * Dequeue a signal and return the element to the caller, which is
622 * expected to free it.
623 *
624 * All callers have to hold the siglock.
625 */
626int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
627 kernel_siginfo_t *info, enum pid_type *type)
628{
629 bool resched_timer = false;
630 int signr;
631
632 /* We only dequeue private signals from ourselves, we don't let
633 * signalfd steal them
634 */
635 *type = PIDTYPE_PID;
636 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
637 if (!signr) {
638 *type = PIDTYPE_TGID;
639 signr = __dequeue_signal(&tsk->signal->shared_pending,
640 mask, info, &resched_timer);
641#ifdef CONFIG_POSIX_TIMERS
642 /*
643 * itimer signal ?
644 *
645 * itimers are process shared and we restart periodic
646 * itimers in the signal delivery path to prevent DoS
647 * attacks in the high resolution timer case. This is
648 * compliant with the old way of self-restarting
649 * itimers, as the SIGALRM is a legacy signal and only
650 * queued once. Changing the restart behaviour to
651 * restart the timer in the signal dequeue path is
652 * reducing the timer noise on heavy loaded !highres
653 * systems too.
654 */
655 if (unlikely(signr == SIGALRM)) {
656 struct hrtimer *tmr = &tsk->signal->real_timer;
657
658 if (!hrtimer_is_queued(tmr) &&
659 tsk->signal->it_real_incr != 0) {
660 hrtimer_forward(tmr, tmr->base->get_time(),
661 tsk->signal->it_real_incr);
662 hrtimer_restart(tmr);
663 }
664 }
665#endif
666 }
667
668 recalc_sigpending();
669 if (!signr)
670 return 0;
671
672 if (unlikely(sig_kernel_stop(signr))) {
673 /*
674 * Set a marker that we have dequeued a stop signal. Our
675 * caller might release the siglock and then the pending
676 * stop signal it is about to process is no longer in the
677 * pending bitmasks, but must still be cleared by a SIGCONT
678 * (and overruled by a SIGKILL). So those cases clear this
679 * shared flag after we've set it. Note that this flag may
680 * remain set after the signal we return is ignored or
681 * handled. That doesn't matter because its only purpose
682 * is to alert stop-signal processing code when another
683 * processor has come along and cleared the flag.
684 */
685 current->jobctl |= JOBCTL_STOP_DEQUEUED;
686 }
687#ifdef CONFIG_POSIX_TIMERS
688 if (resched_timer) {
689 /*
690 * Release the siglock to ensure proper locking order
691 * of timer locks outside of siglocks. Note, we leave
692 * irqs disabled here, since the posix-timers code is
693 * about to disable them again anyway.
694 */
695 spin_unlock(&tsk->sighand->siglock);
696 posixtimer_rearm(info);
697 spin_lock(&tsk->sighand->siglock);
698
699 /* Don't expose the si_sys_private value to userspace */
700 info->si_sys_private = 0;
701 }
702#endif
703 return signr;
704}
705EXPORT_SYMBOL_GPL(dequeue_signal);
706
707static int dequeue_synchronous_signal(kernel_siginfo_t *info)
708{
709 struct task_struct *tsk = current;
710 struct sigpending *pending = &tsk->pending;
711 struct sigqueue *q, *sync = NULL;
712
713 /*
714 * Might a synchronous signal be in the queue?
715 */
716 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
717 return 0;
718
719 /*
720 * Return the first synchronous signal in the queue.
721 */
722 list_for_each_entry(q, &pending->list, list) {
723 /* Synchronous signals have a positive si_code */
724 if ((q->info.si_code > SI_USER) &&
725 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
726 sync = q;
727 goto next;
728 }
729 }
730 return 0;
731next:
732 /*
733 * Check if there is another siginfo for the same signal.
734 */
735 list_for_each_entry_continue(q, &pending->list, list) {
736 if (q->info.si_signo == sync->info.si_signo)
737 goto still_pending;
738 }
739
740 sigdelset(&pending->signal, sync->info.si_signo);
741 recalc_sigpending();
742still_pending:
743 list_del_init(&sync->list);
744 copy_siginfo(info, &sync->info);
745 __sigqueue_free(sync);
746 return info->si_signo;
747}
748
749/*
750 * Tell a process that it has a new active signal..
751 *
752 * NOTE! we rely on the previous spin_lock to
753 * lock interrupts for us! We can only be called with
754 * "siglock" held, and the local interrupt must
755 * have been disabled when that got acquired!
756 *
757 * No need to set need_resched since signal event passing
758 * goes through ->blocked
759 */
760void signal_wake_up_state(struct task_struct *t, unsigned int state)
761{
762 lockdep_assert_held(&t->sighand->siglock);
763
764 set_tsk_thread_flag(t, TIF_SIGPENDING);
765
766 /*
767 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
768 * case. We don't check t->state here because there is a race with it
769 * executing another processor and just now entering stopped state.
770 * By using wake_up_state, we ensure the process will wake up and
771 * handle its death signal.
772 */
773 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
774 kick_process(t);
775}
776
777/*
778 * Remove signals in mask from the pending set and queue.
779 * Returns 1 if any signals were found.
780 *
781 * All callers must be holding the siglock.
782 */
783static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
784{
785 struct sigqueue *q, *n;
786 sigset_t m;
787
788 sigandsets(&m, mask, &s->signal);
789 if (sigisemptyset(&m))
790 return;
791
792 sigandnsets(&s->signal, &s->signal, mask);
793 list_for_each_entry_safe(q, n, &s->list, list) {
794 if (sigismember(mask, q->info.si_signo)) {
795 list_del_init(&q->list);
796 __sigqueue_free(q);
797 }
798 }
799}
800
801static inline int is_si_special(const struct kernel_siginfo *info)
802{
803 return info <= SEND_SIG_PRIV;
804}
805
806static inline bool si_fromuser(const struct kernel_siginfo *info)
807{
808 return info == SEND_SIG_NOINFO ||
809 (!is_si_special(info) && SI_FROMUSER(info));
810}
811
812/*
813 * called with RCU read lock from check_kill_permission()
814 */
815static bool kill_ok_by_cred(struct task_struct *t)
816{
817 const struct cred *cred = current_cred();
818 const struct cred *tcred = __task_cred(t);
819
820 return uid_eq(cred->euid, tcred->suid) ||
821 uid_eq(cred->euid, tcred->uid) ||
822 uid_eq(cred->uid, tcred->suid) ||
823 uid_eq(cred->uid, tcred->uid) ||
824 ns_capable(tcred->user_ns, CAP_KILL);
825}
826
827/*
828 * Bad permissions for sending the signal
829 * - the caller must hold the RCU read lock
830 */
831static int check_kill_permission(int sig, struct kernel_siginfo *info,
832 struct task_struct *t)
833{
834 struct pid *sid;
835 int error;
836
837 if (!valid_signal(sig))
838 return -EINVAL;
839
840 if (!si_fromuser(info))
841 return 0;
842
843 error = audit_signal_info(sig, t); /* Let audit system see the signal */
844 if (error)
845 return error;
846
847 if (!same_thread_group(current, t) &&
848 !kill_ok_by_cred(t)) {
849 switch (sig) {
850 case SIGCONT:
851 sid = task_session(t);
852 /*
853 * We don't return the error if sid == NULL. The
854 * task was unhashed, the caller must notice this.
855 */
856 if (!sid || sid == task_session(current))
857 break;
858 fallthrough;
859 default:
860 return -EPERM;
861 }
862 }
863
864 return security_task_kill(t, info, sig, NULL);
865}
866
867/**
868 * ptrace_trap_notify - schedule trap to notify ptracer
869 * @t: tracee wanting to notify tracer
870 *
871 * This function schedules sticky ptrace trap which is cleared on the next
872 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
873 * ptracer.
874 *
875 * If @t is running, STOP trap will be taken. If trapped for STOP and
876 * ptracer is listening for events, tracee is woken up so that it can
877 * re-trap for the new event. If trapped otherwise, STOP trap will be
878 * eventually taken without returning to userland after the existing traps
879 * are finished by PTRACE_CONT.
880 *
881 * CONTEXT:
882 * Must be called with @task->sighand->siglock held.
883 */
884static void ptrace_trap_notify(struct task_struct *t)
885{
886 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
887 lockdep_assert_held(&t->sighand->siglock);
888
889 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
890 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
891}
892
893/*
894 * Handle magic process-wide effects of stop/continue signals. Unlike
895 * the signal actions, these happen immediately at signal-generation
896 * time regardless of blocking, ignoring, or handling. This does the
897 * actual continuing for SIGCONT, but not the actual stopping for stop
898 * signals. The process stop is done as a signal action for SIG_DFL.
899 *
900 * Returns true if the signal should be actually delivered, otherwise
901 * it should be dropped.
902 */
903static bool prepare_signal(int sig, struct task_struct *p, bool force)
904{
905 struct signal_struct *signal = p->signal;
906 struct task_struct *t;
907 sigset_t flush;
908
909 if (signal->flags & SIGNAL_GROUP_EXIT) {
910 if (signal->core_state)
911 return sig == SIGKILL;
912 /*
913 * The process is in the middle of dying, drop the signal.
914 */
915 return false;
916 } else if (sig_kernel_stop(sig)) {
917 /*
918 * This is a stop signal. Remove SIGCONT from all queues.
919 */
920 siginitset(&flush, sigmask(SIGCONT));
921 flush_sigqueue_mask(&flush, &signal->shared_pending);
922 for_each_thread(p, t)
923 flush_sigqueue_mask(&flush, &t->pending);
924 } else if (sig == SIGCONT) {
925 unsigned int why;
926 /*
927 * Remove all stop signals from all queues, wake all threads.
928 */
929 siginitset(&flush, SIG_KERNEL_STOP_MASK);
930 flush_sigqueue_mask(&flush, &signal->shared_pending);
931 for_each_thread(p, t) {
932 flush_sigqueue_mask(&flush, &t->pending);
933 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
934 if (likely(!(t->ptrace & PT_SEIZED))) {
935 t->jobctl &= ~JOBCTL_STOPPED;
936 wake_up_state(t, __TASK_STOPPED);
937 } else
938 ptrace_trap_notify(t);
939 }
940
941 /*
942 * Notify the parent with CLD_CONTINUED if we were stopped.
943 *
944 * If we were in the middle of a group stop, we pretend it
945 * was already finished, and then continued. Since SIGCHLD
946 * doesn't queue we report only CLD_STOPPED, as if the next
947 * CLD_CONTINUED was dropped.
948 */
949 why = 0;
950 if (signal->flags & SIGNAL_STOP_STOPPED)
951 why |= SIGNAL_CLD_CONTINUED;
952 else if (signal->group_stop_count)
953 why |= SIGNAL_CLD_STOPPED;
954
955 if (why) {
956 /*
957 * The first thread which returns from do_signal_stop()
958 * will take ->siglock, notice SIGNAL_CLD_MASK, and
959 * notify its parent. See get_signal().
960 */
961 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
962 signal->group_stop_count = 0;
963 signal->group_exit_code = 0;
964 }
965 }
966
967 return !sig_ignored(p, sig, force);
968}
969
970/*
971 * Test if P wants to take SIG. After we've checked all threads with this,
972 * it's equivalent to finding no threads not blocking SIG. Any threads not
973 * blocking SIG were ruled out because they are not running and already
974 * have pending signals. Such threads will dequeue from the shared queue
975 * as soon as they're available, so putting the signal on the shared queue
976 * will be equivalent to sending it to one such thread.
977 */
978static inline bool wants_signal(int sig, struct task_struct *p)
979{
980 if (sigismember(&p->blocked, sig))
981 return false;
982
983 if (p->flags & PF_EXITING)
984 return false;
985
986 if (sig == SIGKILL)
987 return true;
988
989 if (task_is_stopped_or_traced(p))
990 return false;
991
992 return task_curr(p) || !task_sigpending(p);
993}
994
995static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
996{
997 struct signal_struct *signal = p->signal;
998 struct task_struct *t;
999
1000 /*
1001 * Now find a thread we can wake up to take the signal off the queue.
1002 *
1003 * Try the suggested task first (may or may not be the main thread).
1004 */
1005 if (wants_signal(sig, p))
1006 t = p;
1007 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1008 /*
1009 * There is just one thread and it does not need to be woken.
1010 * It will dequeue unblocked signals before it runs again.
1011 */
1012 return;
1013 else {
1014 /*
1015 * Otherwise try to find a suitable thread.
1016 */
1017 t = signal->curr_target;
1018 while (!wants_signal(sig, t)) {
1019 t = next_thread(t);
1020 if (t == signal->curr_target)
1021 /*
1022 * No thread needs to be woken.
1023 * Any eligible threads will see
1024 * the signal in the queue soon.
1025 */
1026 return;
1027 }
1028 signal->curr_target = t;
1029 }
1030
1031 /*
1032 * Found a killable thread. If the signal will be fatal,
1033 * then start taking the whole group down immediately.
1034 */
1035 if (sig_fatal(p, sig) &&
1036 (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1037 !sigismember(&t->real_blocked, sig) &&
1038 (sig == SIGKILL || !p->ptrace)) {
1039 /*
1040 * This signal will be fatal to the whole group.
1041 */
1042 if (!sig_kernel_coredump(sig)) {
1043 /*
1044 * Start a group exit and wake everybody up.
1045 * This way we don't have other threads
1046 * running and doing things after a slower
1047 * thread has the fatal signal pending.
1048 */
1049 signal->flags = SIGNAL_GROUP_EXIT;
1050 signal->group_exit_code = sig;
1051 signal->group_stop_count = 0;
1052 __for_each_thread(signal, t) {
1053 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1054 sigaddset(&t->pending.signal, SIGKILL);
1055 signal_wake_up(t, 1);
1056 }
1057 return;
1058 }
1059 }
1060
1061 /*
1062 * The signal is already in the shared-pending queue.
1063 * Tell the chosen thread to wake up and dequeue it.
1064 */
1065 signal_wake_up(t, sig == SIGKILL);
1066 return;
1067}
1068
1069static inline bool legacy_queue(struct sigpending *signals, int sig)
1070{
1071 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1072}
1073
1074static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1075 struct task_struct *t, enum pid_type type, bool force)
1076{
1077 struct sigpending *pending;
1078 struct sigqueue *q;
1079 int override_rlimit;
1080 int ret = 0, result;
1081
1082 lockdep_assert_held(&t->sighand->siglock);
1083
1084 result = TRACE_SIGNAL_IGNORED;
1085 if (!prepare_signal(sig, t, force))
1086 goto ret;
1087
1088 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1089 /*
1090 * Short-circuit ignored signals and support queuing
1091 * exactly one non-rt signal, so that we can get more
1092 * detailed information about the cause of the signal.
1093 */
1094 result = TRACE_SIGNAL_ALREADY_PENDING;
1095 if (legacy_queue(pending, sig))
1096 goto ret;
1097
1098 result = TRACE_SIGNAL_DELIVERED;
1099 /*
1100 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1101 */
1102 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1103 goto out_set;
1104
1105 /*
1106 * Real-time signals must be queued if sent by sigqueue, or
1107 * some other real-time mechanism. It is implementation
1108 * defined whether kill() does so. We attempt to do so, on
1109 * the principle of least surprise, but since kill is not
1110 * allowed to fail with EAGAIN when low on memory we just
1111 * make sure at least one signal gets delivered and don't
1112 * pass on the info struct.
1113 */
1114 if (sig < SIGRTMIN)
1115 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1116 else
1117 override_rlimit = 0;
1118
1119 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1120
1121 if (q) {
1122 list_add_tail(&q->list, &pending->list);
1123 switch ((unsigned long) info) {
1124 case (unsigned long) SEND_SIG_NOINFO:
1125 clear_siginfo(&q->info);
1126 q->info.si_signo = sig;
1127 q->info.si_errno = 0;
1128 q->info.si_code = SI_USER;
1129 q->info.si_pid = task_tgid_nr_ns(current,
1130 task_active_pid_ns(t));
1131 rcu_read_lock();
1132 q->info.si_uid =
1133 from_kuid_munged(task_cred_xxx(t, user_ns),
1134 current_uid());
1135 rcu_read_unlock();
1136 break;
1137 case (unsigned long) SEND_SIG_PRIV:
1138 clear_siginfo(&q->info);
1139 q->info.si_signo = sig;
1140 q->info.si_errno = 0;
1141 q->info.si_code = SI_KERNEL;
1142 q->info.si_pid = 0;
1143 q->info.si_uid = 0;
1144 break;
1145 default:
1146 copy_siginfo(&q->info, info);
1147 break;
1148 }
1149 } else if (!is_si_special(info) &&
1150 sig >= SIGRTMIN && info->si_code != SI_USER) {
1151 /*
1152 * Queue overflow, abort. We may abort if the
1153 * signal was rt and sent by user using something
1154 * other than kill().
1155 */
1156 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1157 ret = -EAGAIN;
1158 goto ret;
1159 } else {
1160 /*
1161 * This is a silent loss of information. We still
1162 * send the signal, but the *info bits are lost.
1163 */
1164 result = TRACE_SIGNAL_LOSE_INFO;
1165 }
1166
1167out_set:
1168 signalfd_notify(t, sig);
1169 sigaddset(&pending->signal, sig);
1170
1171 /* Let multiprocess signals appear after on-going forks */
1172 if (type > PIDTYPE_TGID) {
1173 struct multiprocess_signals *delayed;
1174 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1175 sigset_t *signal = &delayed->signal;
1176 /* Can't queue both a stop and a continue signal */
1177 if (sig == SIGCONT)
1178 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1179 else if (sig_kernel_stop(sig))
1180 sigdelset(signal, SIGCONT);
1181 sigaddset(signal, sig);
1182 }
1183 }
1184
1185 complete_signal(sig, t, type);
1186ret:
1187 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1188 return ret;
1189}
1190
1191static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1192{
1193 bool ret = false;
1194 switch (siginfo_layout(info->si_signo, info->si_code)) {
1195 case SIL_KILL:
1196 case SIL_CHLD:
1197 case SIL_RT:
1198 ret = true;
1199 break;
1200 case SIL_TIMER:
1201 case SIL_POLL:
1202 case SIL_FAULT:
1203 case SIL_FAULT_TRAPNO:
1204 case SIL_FAULT_MCEERR:
1205 case SIL_FAULT_BNDERR:
1206 case SIL_FAULT_PKUERR:
1207 case SIL_FAULT_PERF_EVENT:
1208 case SIL_SYS:
1209 ret = false;
1210 break;
1211 }
1212 return ret;
1213}
1214
1215int send_signal_locked(int sig, struct kernel_siginfo *info,
1216 struct task_struct *t, enum pid_type type)
1217{
1218 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1219 bool force = false;
1220
1221 if (info == SEND_SIG_NOINFO) {
1222 /* Force if sent from an ancestor pid namespace */
1223 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1224 } else if (info == SEND_SIG_PRIV) {
1225 /* Don't ignore kernel generated signals */
1226 force = true;
1227 } else if (has_si_pid_and_uid(info)) {
1228 /* SIGKILL and SIGSTOP is special or has ids */
1229 struct user_namespace *t_user_ns;
1230
1231 rcu_read_lock();
1232 t_user_ns = task_cred_xxx(t, user_ns);
1233 if (current_user_ns() != t_user_ns) {
1234 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1235 info->si_uid = from_kuid_munged(t_user_ns, uid);
1236 }
1237 rcu_read_unlock();
1238
1239 /* A kernel generated signal? */
1240 force = (info->si_code == SI_KERNEL);
1241
1242 /* From an ancestor pid namespace? */
1243 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1244 info->si_pid = 0;
1245 force = true;
1246 }
1247 }
1248 return __send_signal_locked(sig, info, t, type, force);
1249}
1250
1251static void print_fatal_signal(int signr)
1252{
1253 struct pt_regs *regs = task_pt_regs(current);
1254 struct file *exe_file;
1255
1256 exe_file = get_task_exe_file(current);
1257 if (exe_file) {
1258 pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1259 exe_file, current->comm, signr);
1260 fput(exe_file);
1261 } else {
1262 pr_info("%s: potentially unexpected fatal signal %d.\n",
1263 current->comm, signr);
1264 }
1265
1266#if defined(__i386__) && !defined(__arch_um__)
1267 pr_info("code at %08lx: ", regs->ip);
1268 {
1269 int i;
1270 for (i = 0; i < 16; i++) {
1271 unsigned char insn;
1272
1273 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1274 break;
1275 pr_cont("%02x ", insn);
1276 }
1277 }
1278 pr_cont("\n");
1279#endif
1280 preempt_disable();
1281 show_regs(regs);
1282 preempt_enable();
1283}
1284
1285static int __init setup_print_fatal_signals(char *str)
1286{
1287 get_option (&str, &print_fatal_signals);
1288
1289 return 1;
1290}
1291
1292__setup("print-fatal-signals=", setup_print_fatal_signals);
1293
1294int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1295 enum pid_type type)
1296{
1297 unsigned long flags;
1298 int ret = -ESRCH;
1299
1300 if (lock_task_sighand(p, &flags)) {
1301 ret = send_signal_locked(sig, info, p, type);
1302 unlock_task_sighand(p, &flags);
1303 }
1304
1305 return ret;
1306}
1307
1308enum sig_handler {
1309 HANDLER_CURRENT, /* If reachable use the current handler */
1310 HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1311 HANDLER_EXIT, /* Only visible as the process exit code */
1312};
1313
1314/*
1315 * Force a signal that the process can't ignore: if necessary
1316 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1317 *
1318 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1319 * since we do not want to have a signal handler that was blocked
1320 * be invoked when user space had explicitly blocked it.
1321 *
1322 * We don't want to have recursive SIGSEGV's etc, for example,
1323 * that is why we also clear SIGNAL_UNKILLABLE.
1324 */
1325static int
1326force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1327 enum sig_handler handler)
1328{
1329 unsigned long int flags;
1330 int ret, blocked, ignored;
1331 struct k_sigaction *action;
1332 int sig = info->si_signo;
1333
1334 spin_lock_irqsave(&t->sighand->siglock, flags);
1335 action = &t->sighand->action[sig-1];
1336 ignored = action->sa.sa_handler == SIG_IGN;
1337 blocked = sigismember(&t->blocked, sig);
1338 if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1339 action->sa.sa_handler = SIG_DFL;
1340 if (handler == HANDLER_EXIT)
1341 action->sa.sa_flags |= SA_IMMUTABLE;
1342 if (blocked)
1343 sigdelset(&t->blocked, sig);
1344 }
1345 /*
1346 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1347 * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1348 */
1349 if (action->sa.sa_handler == SIG_DFL &&
1350 (!t->ptrace || (handler == HANDLER_EXIT)))
1351 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1352 ret = send_signal_locked(sig, info, t, PIDTYPE_PID);
1353 /* This can happen if the signal was already pending and blocked */
1354 if (!task_sigpending(t))
1355 signal_wake_up(t, 0);
1356 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1357
1358 return ret;
1359}
1360
1361int force_sig_info(struct kernel_siginfo *info)
1362{
1363 return force_sig_info_to_task(info, current, HANDLER_CURRENT);
1364}
1365
1366/*
1367 * Nuke all other threads in the group.
1368 */
1369int zap_other_threads(struct task_struct *p)
1370{
1371 struct task_struct *t;
1372 int count = 0;
1373
1374 p->signal->group_stop_count = 0;
1375
1376 for_other_threads(p, t) {
1377 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1378 /* Don't require de_thread to wait for the vhost_worker */
1379 if ((t->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)
1380 count++;
1381
1382 /* Don't bother with already dead threads */
1383 if (t->exit_state)
1384 continue;
1385 sigaddset(&t->pending.signal, SIGKILL);
1386 signal_wake_up(t, 1);
1387 }
1388
1389 return count;
1390}
1391
1392struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1393 unsigned long *flags)
1394{
1395 struct sighand_struct *sighand;
1396
1397 rcu_read_lock();
1398 for (;;) {
1399 sighand = rcu_dereference(tsk->sighand);
1400 if (unlikely(sighand == NULL))
1401 break;
1402
1403 /*
1404 * This sighand can be already freed and even reused, but
1405 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1406 * initializes ->siglock: this slab can't go away, it has
1407 * the same object type, ->siglock can't be reinitialized.
1408 *
1409 * We need to ensure that tsk->sighand is still the same
1410 * after we take the lock, we can race with de_thread() or
1411 * __exit_signal(). In the latter case the next iteration
1412 * must see ->sighand == NULL.
1413 */
1414 spin_lock_irqsave(&sighand->siglock, *flags);
1415 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1416 break;
1417 spin_unlock_irqrestore(&sighand->siglock, *flags);
1418 }
1419 rcu_read_unlock();
1420
1421 return sighand;
1422}
1423
1424#ifdef CONFIG_LOCKDEP
1425void lockdep_assert_task_sighand_held(struct task_struct *task)
1426{
1427 struct sighand_struct *sighand;
1428
1429 rcu_read_lock();
1430 sighand = rcu_dereference(task->sighand);
1431 if (sighand)
1432 lockdep_assert_held(&sighand->siglock);
1433 else
1434 WARN_ON_ONCE(1);
1435 rcu_read_unlock();
1436}
1437#endif
1438
1439/*
1440 * send signal info to all the members of a thread group or to the
1441 * individual thread if type == PIDTYPE_PID.
1442 */
1443int group_send_sig_info(int sig, struct kernel_siginfo *info,
1444 struct task_struct *p, enum pid_type type)
1445{
1446 int ret;
1447
1448 rcu_read_lock();
1449 ret = check_kill_permission(sig, info, p);
1450 rcu_read_unlock();
1451
1452 if (!ret && sig)
1453 ret = do_send_sig_info(sig, info, p, type);
1454
1455 return ret;
1456}
1457
1458/*
1459 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1460 * control characters do (^C, ^Z etc)
1461 * - the caller must hold at least a readlock on tasklist_lock
1462 */
1463int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1464{
1465 struct task_struct *p = NULL;
1466 int ret = -ESRCH;
1467
1468 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1469 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1470 /*
1471 * If group_send_sig_info() succeeds at least once ret
1472 * becomes 0 and after that the code below has no effect.
1473 * Otherwise we return the last err or -ESRCH if this
1474 * process group is empty.
1475 */
1476 if (ret)
1477 ret = err;
1478 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1479
1480 return ret;
1481}
1482
1483static int kill_pid_info_type(int sig, struct kernel_siginfo *info,
1484 struct pid *pid, enum pid_type type)
1485{
1486 int error = -ESRCH;
1487 struct task_struct *p;
1488
1489 for (;;) {
1490 rcu_read_lock();
1491 p = pid_task(pid, PIDTYPE_PID);
1492 if (p)
1493 error = group_send_sig_info(sig, info, p, type);
1494 rcu_read_unlock();
1495 if (likely(!p || error != -ESRCH))
1496 return error;
1497 /*
1498 * The task was unhashed in between, try again. If it
1499 * is dead, pid_task() will return NULL, if we race with
1500 * de_thread() it will find the new leader.
1501 */
1502 }
1503}
1504
1505int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1506{
1507 return kill_pid_info_type(sig, info, pid, PIDTYPE_TGID);
1508}
1509
1510static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1511{
1512 int error;
1513 rcu_read_lock();
1514 error = kill_pid_info(sig, info, find_vpid(pid));
1515 rcu_read_unlock();
1516 return error;
1517}
1518
1519static inline bool kill_as_cred_perm(const struct cred *cred,
1520 struct task_struct *target)
1521{
1522 const struct cred *pcred = __task_cred(target);
1523
1524 return uid_eq(cred->euid, pcred->suid) ||
1525 uid_eq(cred->euid, pcred->uid) ||
1526 uid_eq(cred->uid, pcred->suid) ||
1527 uid_eq(cred->uid, pcred->uid);
1528}
1529
1530/*
1531 * The usb asyncio usage of siginfo is wrong. The glibc support
1532 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1533 * AKA after the generic fields:
1534 * kernel_pid_t si_pid;
1535 * kernel_uid32_t si_uid;
1536 * sigval_t si_value;
1537 *
1538 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1539 * after the generic fields is:
1540 * void __user *si_addr;
1541 *
1542 * This is a practical problem when there is a 64bit big endian kernel
1543 * and a 32bit userspace. As the 32bit address will encoded in the low
1544 * 32bits of the pointer. Those low 32bits will be stored at higher
1545 * address than appear in a 32 bit pointer. So userspace will not
1546 * see the address it was expecting for it's completions.
1547 *
1548 * There is nothing in the encoding that can allow
1549 * copy_siginfo_to_user32 to detect this confusion of formats, so
1550 * handle this by requiring the caller of kill_pid_usb_asyncio to
1551 * notice when this situration takes place and to store the 32bit
1552 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1553 * parameter.
1554 */
1555int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1556 struct pid *pid, const struct cred *cred)
1557{
1558 struct kernel_siginfo info;
1559 struct task_struct *p;
1560 unsigned long flags;
1561 int ret = -EINVAL;
1562
1563 if (!valid_signal(sig))
1564 return ret;
1565
1566 clear_siginfo(&info);
1567 info.si_signo = sig;
1568 info.si_errno = errno;
1569 info.si_code = SI_ASYNCIO;
1570 *((sigval_t *)&info.si_pid) = addr;
1571
1572 rcu_read_lock();
1573 p = pid_task(pid, PIDTYPE_PID);
1574 if (!p) {
1575 ret = -ESRCH;
1576 goto out_unlock;
1577 }
1578 if (!kill_as_cred_perm(cred, p)) {
1579 ret = -EPERM;
1580 goto out_unlock;
1581 }
1582 ret = security_task_kill(p, &info, sig, cred);
1583 if (ret)
1584 goto out_unlock;
1585
1586 if (sig) {
1587 if (lock_task_sighand(p, &flags)) {
1588 ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false);
1589 unlock_task_sighand(p, &flags);
1590 } else
1591 ret = -ESRCH;
1592 }
1593out_unlock:
1594 rcu_read_unlock();
1595 return ret;
1596}
1597EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1598
1599/*
1600 * kill_something_info() interprets pid in interesting ways just like kill(2).
1601 *
1602 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1603 * is probably wrong. Should make it like BSD or SYSV.
1604 */
1605
1606static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1607{
1608 int ret;
1609
1610 if (pid > 0)
1611 return kill_proc_info(sig, info, pid);
1612
1613 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1614 if (pid == INT_MIN)
1615 return -ESRCH;
1616
1617 read_lock(&tasklist_lock);
1618 if (pid != -1) {
1619 ret = __kill_pgrp_info(sig, info,
1620 pid ? find_vpid(-pid) : task_pgrp(current));
1621 } else {
1622 int retval = 0, count = 0;
1623 struct task_struct * p;
1624
1625 for_each_process(p) {
1626 if (task_pid_vnr(p) > 1 &&
1627 !same_thread_group(p, current)) {
1628 int err = group_send_sig_info(sig, info, p,
1629 PIDTYPE_MAX);
1630 ++count;
1631 if (err != -EPERM)
1632 retval = err;
1633 }
1634 }
1635 ret = count ? retval : -ESRCH;
1636 }
1637 read_unlock(&tasklist_lock);
1638
1639 return ret;
1640}
1641
1642/*
1643 * These are for backward compatibility with the rest of the kernel source.
1644 */
1645
1646int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1647{
1648 /*
1649 * Make sure legacy kernel users don't send in bad values
1650 * (normal paths check this in check_kill_permission).
1651 */
1652 if (!valid_signal(sig))
1653 return -EINVAL;
1654
1655 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1656}
1657EXPORT_SYMBOL(send_sig_info);
1658
1659#define __si_special(priv) \
1660 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1661
1662int
1663send_sig(int sig, struct task_struct *p, int priv)
1664{
1665 return send_sig_info(sig, __si_special(priv), p);
1666}
1667EXPORT_SYMBOL(send_sig);
1668
1669void force_sig(int sig)
1670{
1671 struct kernel_siginfo info;
1672
1673 clear_siginfo(&info);
1674 info.si_signo = sig;
1675 info.si_errno = 0;
1676 info.si_code = SI_KERNEL;
1677 info.si_pid = 0;
1678 info.si_uid = 0;
1679 force_sig_info(&info);
1680}
1681EXPORT_SYMBOL(force_sig);
1682
1683void force_fatal_sig(int sig)
1684{
1685 struct kernel_siginfo info;
1686
1687 clear_siginfo(&info);
1688 info.si_signo = sig;
1689 info.si_errno = 0;
1690 info.si_code = SI_KERNEL;
1691 info.si_pid = 0;
1692 info.si_uid = 0;
1693 force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
1694}
1695
1696void force_exit_sig(int sig)
1697{
1698 struct kernel_siginfo info;
1699
1700 clear_siginfo(&info);
1701 info.si_signo = sig;
1702 info.si_errno = 0;
1703 info.si_code = SI_KERNEL;
1704 info.si_pid = 0;
1705 info.si_uid = 0;
1706 force_sig_info_to_task(&info, current, HANDLER_EXIT);
1707}
1708
1709/*
1710 * When things go south during signal handling, we
1711 * will force a SIGSEGV. And if the signal that caused
1712 * the problem was already a SIGSEGV, we'll want to
1713 * make sure we don't even try to deliver the signal..
1714 */
1715void force_sigsegv(int sig)
1716{
1717 if (sig == SIGSEGV)
1718 force_fatal_sig(SIGSEGV);
1719 else
1720 force_sig(SIGSEGV);
1721}
1722
1723int force_sig_fault_to_task(int sig, int code, void __user *addr,
1724 struct task_struct *t)
1725{
1726 struct kernel_siginfo info;
1727
1728 clear_siginfo(&info);
1729 info.si_signo = sig;
1730 info.si_errno = 0;
1731 info.si_code = code;
1732 info.si_addr = addr;
1733 return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
1734}
1735
1736int force_sig_fault(int sig, int code, void __user *addr)
1737{
1738 return force_sig_fault_to_task(sig, code, addr, current);
1739}
1740
1741int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t)
1742{
1743 struct kernel_siginfo info;
1744
1745 clear_siginfo(&info);
1746 info.si_signo = sig;
1747 info.si_errno = 0;
1748 info.si_code = code;
1749 info.si_addr = addr;
1750 return send_sig_info(info.si_signo, &info, t);
1751}
1752
1753int force_sig_mceerr(int code, void __user *addr, short lsb)
1754{
1755 struct kernel_siginfo info;
1756
1757 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1758 clear_siginfo(&info);
1759 info.si_signo = SIGBUS;
1760 info.si_errno = 0;
1761 info.si_code = code;
1762 info.si_addr = addr;
1763 info.si_addr_lsb = lsb;
1764 return force_sig_info(&info);
1765}
1766
1767int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1768{
1769 struct kernel_siginfo info;
1770
1771 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1772 clear_siginfo(&info);
1773 info.si_signo = SIGBUS;
1774 info.si_errno = 0;
1775 info.si_code = code;
1776 info.si_addr = addr;
1777 info.si_addr_lsb = lsb;
1778 return send_sig_info(info.si_signo, &info, t);
1779}
1780EXPORT_SYMBOL(send_sig_mceerr);
1781
1782int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1783{
1784 struct kernel_siginfo info;
1785
1786 clear_siginfo(&info);
1787 info.si_signo = SIGSEGV;
1788 info.si_errno = 0;
1789 info.si_code = SEGV_BNDERR;
1790 info.si_addr = addr;
1791 info.si_lower = lower;
1792 info.si_upper = upper;
1793 return force_sig_info(&info);
1794}
1795
1796#ifdef SEGV_PKUERR
1797int force_sig_pkuerr(void __user *addr, u32 pkey)
1798{
1799 struct kernel_siginfo info;
1800
1801 clear_siginfo(&info);
1802 info.si_signo = SIGSEGV;
1803 info.si_errno = 0;
1804 info.si_code = SEGV_PKUERR;
1805 info.si_addr = addr;
1806 info.si_pkey = pkey;
1807 return force_sig_info(&info);
1808}
1809#endif
1810
1811int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1812{
1813 struct kernel_siginfo info;
1814
1815 clear_siginfo(&info);
1816 info.si_signo = SIGTRAP;
1817 info.si_errno = 0;
1818 info.si_code = TRAP_PERF;
1819 info.si_addr = addr;
1820 info.si_perf_data = sig_data;
1821 info.si_perf_type = type;
1822
1823 /*
1824 * Signals generated by perf events should not terminate the whole
1825 * process if SIGTRAP is blocked, however, delivering the signal
1826 * asynchronously is better than not delivering at all. But tell user
1827 * space if the signal was asynchronous, so it can clearly be
1828 * distinguished from normal synchronous ones.
1829 */
1830 info.si_perf_flags = sigismember(¤t->blocked, info.si_signo) ?
1831 TRAP_PERF_FLAG_ASYNC :
1832 0;
1833
1834 return send_sig_info(info.si_signo, &info, current);
1835}
1836
1837/**
1838 * force_sig_seccomp - signals the task to allow in-process syscall emulation
1839 * @syscall: syscall number to send to userland
1840 * @reason: filter-supplied reason code to send to userland (via si_errno)
1841 * @force_coredump: true to trigger a coredump
1842 *
1843 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1844 */
1845int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1846{
1847 struct kernel_siginfo info;
1848
1849 clear_siginfo(&info);
1850 info.si_signo = SIGSYS;
1851 info.si_code = SYS_SECCOMP;
1852 info.si_call_addr = (void __user *)KSTK_EIP(current);
1853 info.si_errno = reason;
1854 info.si_arch = syscall_get_arch(current);
1855 info.si_syscall = syscall;
1856 return force_sig_info_to_task(&info, current,
1857 force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1858}
1859
1860/* For the crazy architectures that include trap information in
1861 * the errno field, instead of an actual errno value.
1862 */
1863int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1864{
1865 struct kernel_siginfo info;
1866
1867 clear_siginfo(&info);
1868 info.si_signo = SIGTRAP;
1869 info.si_errno = errno;
1870 info.si_code = TRAP_HWBKPT;
1871 info.si_addr = addr;
1872 return force_sig_info(&info);
1873}
1874
1875/* For the rare architectures that include trap information using
1876 * si_trapno.
1877 */
1878int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1879{
1880 struct kernel_siginfo info;
1881
1882 clear_siginfo(&info);
1883 info.si_signo = sig;
1884 info.si_errno = 0;
1885 info.si_code = code;
1886 info.si_addr = addr;
1887 info.si_trapno = trapno;
1888 return force_sig_info(&info);
1889}
1890
1891/* For the rare architectures that include trap information using
1892 * si_trapno.
1893 */
1894int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1895 struct task_struct *t)
1896{
1897 struct kernel_siginfo info;
1898
1899 clear_siginfo(&info);
1900 info.si_signo = sig;
1901 info.si_errno = 0;
1902 info.si_code = code;
1903 info.si_addr = addr;
1904 info.si_trapno = trapno;
1905 return send_sig_info(info.si_signo, &info, t);
1906}
1907
1908static int kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1909{
1910 int ret;
1911 read_lock(&tasklist_lock);
1912 ret = __kill_pgrp_info(sig, info, pgrp);
1913 read_unlock(&tasklist_lock);
1914 return ret;
1915}
1916
1917int kill_pgrp(struct pid *pid, int sig, int priv)
1918{
1919 return kill_pgrp_info(sig, __si_special(priv), pid);
1920}
1921EXPORT_SYMBOL(kill_pgrp);
1922
1923int kill_pid(struct pid *pid, int sig, int priv)
1924{
1925 return kill_pid_info(sig, __si_special(priv), pid);
1926}
1927EXPORT_SYMBOL(kill_pid);
1928
1929/*
1930 * These functions support sending signals using preallocated sigqueue
1931 * structures. This is needed "because realtime applications cannot
1932 * afford to lose notifications of asynchronous events, like timer
1933 * expirations or I/O completions". In the case of POSIX Timers
1934 * we allocate the sigqueue structure from the timer_create. If this
1935 * allocation fails we are able to report the failure to the application
1936 * with an EAGAIN error.
1937 */
1938struct sigqueue *sigqueue_alloc(void)
1939{
1940 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1941}
1942
1943void sigqueue_free(struct sigqueue *q)
1944{
1945 unsigned long flags;
1946 spinlock_t *lock = ¤t->sighand->siglock;
1947
1948 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1949 /*
1950 * We must hold ->siglock while testing q->list
1951 * to serialize with collect_signal() or with
1952 * __exit_signal()->flush_sigqueue().
1953 */
1954 spin_lock_irqsave(lock, flags);
1955 q->flags &= ~SIGQUEUE_PREALLOC;
1956 /*
1957 * If it is queued it will be freed when dequeued,
1958 * like the "regular" sigqueue.
1959 */
1960 if (!list_empty(&q->list))
1961 q = NULL;
1962 spin_unlock_irqrestore(lock, flags);
1963
1964 if (q)
1965 __sigqueue_free(q);
1966}
1967
1968int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1969{
1970 int sig = q->info.si_signo;
1971 struct sigpending *pending;
1972 struct task_struct *t;
1973 unsigned long flags;
1974 int ret, result;
1975
1976 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1977
1978 ret = -1;
1979 rcu_read_lock();
1980
1981 /*
1982 * This function is used by POSIX timers to deliver a timer signal.
1983 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1984 * set), the signal must be delivered to the specific thread (queues
1985 * into t->pending).
1986 *
1987 * Where type is not PIDTYPE_PID, signals must be delivered to the
1988 * process. In this case, prefer to deliver to current if it is in
1989 * the same thread group as the target process, which avoids
1990 * unnecessarily waking up a potentially idle task.
1991 */
1992 t = pid_task(pid, type);
1993 if (!t)
1994 goto ret;
1995 if (type != PIDTYPE_PID && same_thread_group(t, current))
1996 t = current;
1997 if (!likely(lock_task_sighand(t, &flags)))
1998 goto ret;
1999
2000 ret = 1; /* the signal is ignored */
2001 result = TRACE_SIGNAL_IGNORED;
2002 if (!prepare_signal(sig, t, false))
2003 goto out;
2004
2005 ret = 0;
2006 if (unlikely(!list_empty(&q->list))) {
2007 /*
2008 * If an SI_TIMER entry is already queue just increment
2009 * the overrun count.
2010 */
2011 BUG_ON(q->info.si_code != SI_TIMER);
2012 q->info.si_overrun++;
2013 result = TRACE_SIGNAL_ALREADY_PENDING;
2014 goto out;
2015 }
2016 q->info.si_overrun = 0;
2017
2018 signalfd_notify(t, sig);
2019 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
2020 list_add_tail(&q->list, &pending->list);
2021 sigaddset(&pending->signal, sig);
2022 complete_signal(sig, t, type);
2023 result = TRACE_SIGNAL_DELIVERED;
2024out:
2025 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
2026 unlock_task_sighand(t, &flags);
2027ret:
2028 rcu_read_unlock();
2029 return ret;
2030}
2031
2032void do_notify_pidfd(struct task_struct *task)
2033{
2034 struct pid *pid = task_pid(task);
2035
2036 WARN_ON(task->exit_state == 0);
2037
2038 __wake_up(&pid->wait_pidfd, TASK_NORMAL, 0,
2039 poll_to_key(EPOLLIN | EPOLLRDNORM));
2040}
2041
2042/*
2043 * Let a parent know about the death of a child.
2044 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2045 *
2046 * Returns true if our parent ignored us and so we've switched to
2047 * self-reaping.
2048 */
2049bool do_notify_parent(struct task_struct *tsk, int sig)
2050{
2051 struct kernel_siginfo info;
2052 unsigned long flags;
2053 struct sighand_struct *psig;
2054 bool autoreap = false;
2055 u64 utime, stime;
2056
2057 WARN_ON_ONCE(sig == -1);
2058
2059 /* do_notify_parent_cldstop should have been called instead. */
2060 WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2061
2062 WARN_ON_ONCE(!tsk->ptrace &&
2063 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2064 /*
2065 * tsk is a group leader and has no threads, wake up the
2066 * non-PIDFD_THREAD waiters.
2067 */
2068 if (thread_group_empty(tsk))
2069 do_notify_pidfd(tsk);
2070
2071 if (sig != SIGCHLD) {
2072 /*
2073 * This is only possible if parent == real_parent.
2074 * Check if it has changed security domain.
2075 */
2076 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2077 sig = SIGCHLD;
2078 }
2079
2080 clear_siginfo(&info);
2081 info.si_signo = sig;
2082 info.si_errno = 0;
2083 /*
2084 * We are under tasklist_lock here so our parent is tied to
2085 * us and cannot change.
2086 *
2087 * task_active_pid_ns will always return the same pid namespace
2088 * until a task passes through release_task.
2089 *
2090 * write_lock() currently calls preempt_disable() which is the
2091 * same as rcu_read_lock(), but according to Oleg, this is not
2092 * correct to rely on this
2093 */
2094 rcu_read_lock();
2095 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2096 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2097 task_uid(tsk));
2098 rcu_read_unlock();
2099
2100 task_cputime(tsk, &utime, &stime);
2101 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2102 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2103
2104 info.si_status = tsk->exit_code & 0x7f;
2105 if (tsk->exit_code & 0x80)
2106 info.si_code = CLD_DUMPED;
2107 else if (tsk->exit_code & 0x7f)
2108 info.si_code = CLD_KILLED;
2109 else {
2110 info.si_code = CLD_EXITED;
2111 info.si_status = tsk->exit_code >> 8;
2112 }
2113
2114 psig = tsk->parent->sighand;
2115 spin_lock_irqsave(&psig->siglock, flags);
2116 if (!tsk->ptrace && sig == SIGCHLD &&
2117 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2118 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2119 /*
2120 * We are exiting and our parent doesn't care. POSIX.1
2121 * defines special semantics for setting SIGCHLD to SIG_IGN
2122 * or setting the SA_NOCLDWAIT flag: we should be reaped
2123 * automatically and not left for our parent's wait4 call.
2124 * Rather than having the parent do it as a magic kind of
2125 * signal handler, we just set this to tell do_exit that we
2126 * can be cleaned up without becoming a zombie. Note that
2127 * we still call __wake_up_parent in this case, because a
2128 * blocked sys_wait4 might now return -ECHILD.
2129 *
2130 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2131 * is implementation-defined: we do (if you don't want
2132 * it, just use SIG_IGN instead).
2133 */
2134 autoreap = true;
2135 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2136 sig = 0;
2137 }
2138 /*
2139 * Send with __send_signal as si_pid and si_uid are in the
2140 * parent's namespaces.
2141 */
2142 if (valid_signal(sig) && sig)
2143 __send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2144 __wake_up_parent(tsk, tsk->parent);
2145 spin_unlock_irqrestore(&psig->siglock, flags);
2146
2147 return autoreap;
2148}
2149
2150/**
2151 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2152 * @tsk: task reporting the state change
2153 * @for_ptracer: the notification is for ptracer
2154 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2155 *
2156 * Notify @tsk's parent that the stopped/continued state has changed. If
2157 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2158 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2159 *
2160 * CONTEXT:
2161 * Must be called with tasklist_lock at least read locked.
2162 */
2163static void do_notify_parent_cldstop(struct task_struct *tsk,
2164 bool for_ptracer, int why)
2165{
2166 struct kernel_siginfo info;
2167 unsigned long flags;
2168 struct task_struct *parent;
2169 struct sighand_struct *sighand;
2170 u64 utime, stime;
2171
2172 if (for_ptracer) {
2173 parent = tsk->parent;
2174 } else {
2175 tsk = tsk->group_leader;
2176 parent = tsk->real_parent;
2177 }
2178
2179 clear_siginfo(&info);
2180 info.si_signo = SIGCHLD;
2181 info.si_errno = 0;
2182 /*
2183 * see comment in do_notify_parent() about the following 4 lines
2184 */
2185 rcu_read_lock();
2186 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2187 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2188 rcu_read_unlock();
2189
2190 task_cputime(tsk, &utime, &stime);
2191 info.si_utime = nsec_to_clock_t(utime);
2192 info.si_stime = nsec_to_clock_t(stime);
2193
2194 info.si_code = why;
2195 switch (why) {
2196 case CLD_CONTINUED:
2197 info.si_status = SIGCONT;
2198 break;
2199 case CLD_STOPPED:
2200 info.si_status = tsk->signal->group_exit_code & 0x7f;
2201 break;
2202 case CLD_TRAPPED:
2203 info.si_status = tsk->exit_code & 0x7f;
2204 break;
2205 default:
2206 BUG();
2207 }
2208
2209 sighand = parent->sighand;
2210 spin_lock_irqsave(&sighand->siglock, flags);
2211 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2212 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2213 send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID);
2214 /*
2215 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2216 */
2217 __wake_up_parent(tsk, parent);
2218 spin_unlock_irqrestore(&sighand->siglock, flags);
2219}
2220
2221/*
2222 * This must be called with current->sighand->siglock held.
2223 *
2224 * This should be the path for all ptrace stops.
2225 * We always set current->last_siginfo while stopped here.
2226 * That makes it a way to test a stopped process for
2227 * being ptrace-stopped vs being job-control-stopped.
2228 *
2229 * Returns the signal the ptracer requested the code resume
2230 * with. If the code did not stop because the tracer is gone,
2231 * the stop signal remains unchanged unless clear_code.
2232 */
2233static int ptrace_stop(int exit_code, int why, unsigned long message,
2234 kernel_siginfo_t *info)
2235 __releases(¤t->sighand->siglock)
2236 __acquires(¤t->sighand->siglock)
2237{
2238 bool gstop_done = false;
2239
2240 if (arch_ptrace_stop_needed()) {
2241 /*
2242 * The arch code has something special to do before a
2243 * ptrace stop. This is allowed to block, e.g. for faults
2244 * on user stack pages. We can't keep the siglock while
2245 * calling arch_ptrace_stop, so we must release it now.
2246 * To preserve proper semantics, we must do this before
2247 * any signal bookkeeping like checking group_stop_count.
2248 */
2249 spin_unlock_irq(¤t->sighand->siglock);
2250 arch_ptrace_stop();
2251 spin_lock_irq(¤t->sighand->siglock);
2252 }
2253
2254 /*
2255 * After this point ptrace_signal_wake_up or signal_wake_up
2256 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
2257 * signal comes in. Handle previous ptrace_unlinks and fatal
2258 * signals here to prevent ptrace_stop sleeping in schedule.
2259 */
2260 if (!current->ptrace || __fatal_signal_pending(current))
2261 return exit_code;
2262
2263 set_special_state(TASK_TRACED);
2264 current->jobctl |= JOBCTL_TRACED;
2265
2266 /*
2267 * We're committing to trapping. TRACED should be visible before
2268 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2269 * Also, transition to TRACED and updates to ->jobctl should be
2270 * atomic with respect to siglock and should be done after the arch
2271 * hook as siglock is released and regrabbed across it.
2272 *
2273 * TRACER TRACEE
2274 *
2275 * ptrace_attach()
2276 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2277 * do_wait()
2278 * set_current_state() smp_wmb();
2279 * ptrace_do_wait()
2280 * wait_task_stopped()
2281 * task_stopped_code()
2282 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2283 */
2284 smp_wmb();
2285
2286 current->ptrace_message = message;
2287 current->last_siginfo = info;
2288 current->exit_code = exit_code;
2289
2290 /*
2291 * If @why is CLD_STOPPED, we're trapping to participate in a group
2292 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2293 * across siglock relocks since INTERRUPT was scheduled, PENDING
2294 * could be clear now. We act as if SIGCONT is received after
2295 * TASK_TRACED is entered - ignore it.
2296 */
2297 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2298 gstop_done = task_participate_group_stop(current);
2299
2300 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2301 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2302 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2303 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2304
2305 /* entering a trap, clear TRAPPING */
2306 task_clear_jobctl_trapping(current);
2307
2308 spin_unlock_irq(¤t->sighand->siglock);
2309 read_lock(&tasklist_lock);
2310 /*
2311 * Notify parents of the stop.
2312 *
2313 * While ptraced, there are two parents - the ptracer and
2314 * the real_parent of the group_leader. The ptracer should
2315 * know about every stop while the real parent is only
2316 * interested in the completion of group stop. The states
2317 * for the two don't interact with each other. Notify
2318 * separately unless they're gonna be duplicates.
2319 */
2320 if (current->ptrace)
2321 do_notify_parent_cldstop(current, true, why);
2322 if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2323 do_notify_parent_cldstop(current, false, why);
2324
2325 /*
2326 * The previous do_notify_parent_cldstop() invocation woke ptracer.
2327 * One a PREEMPTION kernel this can result in preemption requirement
2328 * which will be fulfilled after read_unlock() and the ptracer will be
2329 * put on the CPU.
2330 * The ptracer is in wait_task_inactive(, __TASK_TRACED) waiting for
2331 * this task wait in schedule(). If this task gets preempted then it
2332 * remains enqueued on the runqueue. The ptracer will observe this and
2333 * then sleep for a delay of one HZ tick. In the meantime this task
2334 * gets scheduled, enters schedule() and will wait for the ptracer.
2335 *
2336 * This preemption point is not bad from a correctness point of
2337 * view but extends the runtime by one HZ tick time due to the
2338 * ptracer's sleep. The preempt-disable section ensures that there
2339 * will be no preemption between unlock and schedule() and so
2340 * improving the performance since the ptracer will observe that
2341 * the tracee is scheduled out once it gets on the CPU.
2342 *
2343 * On PREEMPT_RT locking tasklist_lock does not disable preemption.
2344 * Therefore the task can be preempted after do_notify_parent_cldstop()
2345 * before unlocking tasklist_lock so there is no benefit in doing this.
2346 *
2347 * In fact disabling preemption is harmful on PREEMPT_RT because
2348 * the spinlock_t in cgroup_enter_frozen() must not be acquired
2349 * with preemption disabled due to the 'sleeping' spinlock
2350 * substitution of RT.
2351 */
2352 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2353 preempt_disable();
2354 read_unlock(&tasklist_lock);
2355 cgroup_enter_frozen();
2356 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2357 preempt_enable_no_resched();
2358 schedule();
2359 cgroup_leave_frozen(true);
2360
2361 /*
2362 * We are back. Now reacquire the siglock before touching
2363 * last_siginfo, so that we are sure to have synchronized with
2364 * any signal-sending on another CPU that wants to examine it.
2365 */
2366 spin_lock_irq(¤t->sighand->siglock);
2367 exit_code = current->exit_code;
2368 current->last_siginfo = NULL;
2369 current->ptrace_message = 0;
2370 current->exit_code = 0;
2371
2372 /* LISTENING can be set only during STOP traps, clear it */
2373 current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2374
2375 /*
2376 * Queued signals ignored us while we were stopped for tracing.
2377 * So check for any that we should take before resuming user mode.
2378 * This sets TIF_SIGPENDING, but never clears it.
2379 */
2380 recalc_sigpending_tsk(current);
2381 return exit_code;
2382}
2383
2384static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2385{
2386 kernel_siginfo_t info;
2387
2388 clear_siginfo(&info);
2389 info.si_signo = signr;
2390 info.si_code = exit_code;
2391 info.si_pid = task_pid_vnr(current);
2392 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2393
2394 /* Let the debugger run. */
2395 return ptrace_stop(exit_code, why, message, &info);
2396}
2397
2398int ptrace_notify(int exit_code, unsigned long message)
2399{
2400 int signr;
2401
2402 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2403 if (unlikely(task_work_pending(current)))
2404 task_work_run();
2405
2406 spin_lock_irq(¤t->sighand->siglock);
2407 signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2408 spin_unlock_irq(¤t->sighand->siglock);
2409 return signr;
2410}
2411
2412/**
2413 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2414 * @signr: signr causing group stop if initiating
2415 *
2416 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2417 * and participate in it. If already set, participate in the existing
2418 * group stop. If participated in a group stop (and thus slept), %true is
2419 * returned with siglock released.
2420 *
2421 * If ptraced, this function doesn't handle stop itself. Instead,
2422 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2423 * untouched. The caller must ensure that INTERRUPT trap handling takes
2424 * places afterwards.
2425 *
2426 * CONTEXT:
2427 * Must be called with @current->sighand->siglock held, which is released
2428 * on %true return.
2429 *
2430 * RETURNS:
2431 * %false if group stop is already cancelled or ptrace trap is scheduled.
2432 * %true if participated in group stop.
2433 */
2434static bool do_signal_stop(int signr)
2435 __releases(¤t->sighand->siglock)
2436{
2437 struct signal_struct *sig = current->signal;
2438
2439 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2440 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2441 struct task_struct *t;
2442
2443 /* signr will be recorded in task->jobctl for retries */
2444 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2445
2446 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2447 unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2448 unlikely(sig->group_exec_task))
2449 return false;
2450 /*
2451 * There is no group stop already in progress. We must
2452 * initiate one now.
2453 *
2454 * While ptraced, a task may be resumed while group stop is
2455 * still in effect and then receive a stop signal and
2456 * initiate another group stop. This deviates from the
2457 * usual behavior as two consecutive stop signals can't
2458 * cause two group stops when !ptraced. That is why we
2459 * also check !task_is_stopped(t) below.
2460 *
2461 * The condition can be distinguished by testing whether
2462 * SIGNAL_STOP_STOPPED is already set. Don't generate
2463 * group_exit_code in such case.
2464 *
2465 * This is not necessary for SIGNAL_STOP_CONTINUED because
2466 * an intervening stop signal is required to cause two
2467 * continued events regardless of ptrace.
2468 */
2469 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2470 sig->group_exit_code = signr;
2471
2472 sig->group_stop_count = 0;
2473 if (task_set_jobctl_pending(current, signr | gstop))
2474 sig->group_stop_count++;
2475
2476 for_other_threads(current, t) {
2477 /*
2478 * Setting state to TASK_STOPPED for a group
2479 * stop is always done with the siglock held,
2480 * so this check has no races.
2481 */
2482 if (!task_is_stopped(t) &&
2483 task_set_jobctl_pending(t, signr | gstop)) {
2484 sig->group_stop_count++;
2485 if (likely(!(t->ptrace & PT_SEIZED)))
2486 signal_wake_up(t, 0);
2487 else
2488 ptrace_trap_notify(t);
2489 }
2490 }
2491 }
2492
2493 if (likely(!current->ptrace)) {
2494 int notify = 0;
2495
2496 /*
2497 * If there are no other threads in the group, or if there
2498 * is a group stop in progress and we are the last to stop,
2499 * report to the parent.
2500 */
2501 if (task_participate_group_stop(current))
2502 notify = CLD_STOPPED;
2503
2504 current->jobctl |= JOBCTL_STOPPED;
2505 set_special_state(TASK_STOPPED);
2506 spin_unlock_irq(¤t->sighand->siglock);
2507
2508 /*
2509 * Notify the parent of the group stop completion. Because
2510 * we're not holding either the siglock or tasklist_lock
2511 * here, ptracer may attach inbetween; however, this is for
2512 * group stop and should always be delivered to the real
2513 * parent of the group leader. The new ptracer will get
2514 * its notification when this task transitions into
2515 * TASK_TRACED.
2516 */
2517 if (notify) {
2518 read_lock(&tasklist_lock);
2519 do_notify_parent_cldstop(current, false, notify);
2520 read_unlock(&tasklist_lock);
2521 }
2522
2523 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2524 cgroup_enter_frozen();
2525 schedule();
2526 return true;
2527 } else {
2528 /*
2529 * While ptraced, group stop is handled by STOP trap.
2530 * Schedule it and let the caller deal with it.
2531 */
2532 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2533 return false;
2534 }
2535}
2536
2537/**
2538 * do_jobctl_trap - take care of ptrace jobctl traps
2539 *
2540 * When PT_SEIZED, it's used for both group stop and explicit
2541 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2542 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2543 * the stop signal; otherwise, %SIGTRAP.
2544 *
2545 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2546 * number as exit_code and no siginfo.
2547 *
2548 * CONTEXT:
2549 * Must be called with @current->sighand->siglock held, which may be
2550 * released and re-acquired before returning with intervening sleep.
2551 */
2552static void do_jobctl_trap(void)
2553{
2554 struct signal_struct *signal = current->signal;
2555 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2556
2557 if (current->ptrace & PT_SEIZED) {
2558 if (!signal->group_stop_count &&
2559 !(signal->flags & SIGNAL_STOP_STOPPED))
2560 signr = SIGTRAP;
2561 WARN_ON_ONCE(!signr);
2562 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2563 CLD_STOPPED, 0);
2564 } else {
2565 WARN_ON_ONCE(!signr);
2566 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2567 }
2568}
2569
2570/**
2571 * do_freezer_trap - handle the freezer jobctl trap
2572 *
2573 * Puts the task into frozen state, if only the task is not about to quit.
2574 * In this case it drops JOBCTL_TRAP_FREEZE.
2575 *
2576 * CONTEXT:
2577 * Must be called with @current->sighand->siglock held,
2578 * which is always released before returning.
2579 */
2580static void do_freezer_trap(void)
2581 __releases(¤t->sighand->siglock)
2582{
2583 /*
2584 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2585 * let's make another loop to give it a chance to be handled.
2586 * In any case, we'll return back.
2587 */
2588 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2589 JOBCTL_TRAP_FREEZE) {
2590 spin_unlock_irq(¤t->sighand->siglock);
2591 return;
2592 }
2593
2594 /*
2595 * Now we're sure that there is no pending fatal signal and no
2596 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2597 * immediately (if there is a non-fatal signal pending), and
2598 * put the task into sleep.
2599 */
2600 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2601 clear_thread_flag(TIF_SIGPENDING);
2602 spin_unlock_irq(¤t->sighand->siglock);
2603 cgroup_enter_frozen();
2604 schedule();
2605}
2606
2607static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2608{
2609 /*
2610 * We do not check sig_kernel_stop(signr) but set this marker
2611 * unconditionally because we do not know whether debugger will
2612 * change signr. This flag has no meaning unless we are going
2613 * to stop after return from ptrace_stop(). In this case it will
2614 * be checked in do_signal_stop(), we should only stop if it was
2615 * not cleared by SIGCONT while we were sleeping. See also the
2616 * comment in dequeue_signal().
2617 */
2618 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2619 signr = ptrace_stop(signr, CLD_TRAPPED, 0, info);
2620
2621 /* We're back. Did the debugger cancel the sig? */
2622 if (signr == 0)
2623 return signr;
2624
2625 /*
2626 * Update the siginfo structure if the signal has
2627 * changed. If the debugger wanted something
2628 * specific in the siginfo structure then it should
2629 * have updated *info via PTRACE_SETSIGINFO.
2630 */
2631 if (signr != info->si_signo) {
2632 clear_siginfo(info);
2633 info->si_signo = signr;
2634 info->si_errno = 0;
2635 info->si_code = SI_USER;
2636 rcu_read_lock();
2637 info->si_pid = task_pid_vnr(current->parent);
2638 info->si_uid = from_kuid_munged(current_user_ns(),
2639 task_uid(current->parent));
2640 rcu_read_unlock();
2641 }
2642
2643 /* If the (new) signal is now blocked, requeue it. */
2644 if (sigismember(¤t->blocked, signr) ||
2645 fatal_signal_pending(current)) {
2646 send_signal_locked(signr, info, current, type);
2647 signr = 0;
2648 }
2649
2650 return signr;
2651}
2652
2653static void hide_si_addr_tag_bits(struct ksignal *ksig)
2654{
2655 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2656 case SIL_FAULT:
2657 case SIL_FAULT_TRAPNO:
2658 case SIL_FAULT_MCEERR:
2659 case SIL_FAULT_BNDERR:
2660 case SIL_FAULT_PKUERR:
2661 case SIL_FAULT_PERF_EVENT:
2662 ksig->info.si_addr = arch_untagged_si_addr(
2663 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2664 break;
2665 case SIL_KILL:
2666 case SIL_TIMER:
2667 case SIL_POLL:
2668 case SIL_CHLD:
2669 case SIL_RT:
2670 case SIL_SYS:
2671 break;
2672 }
2673}
2674
2675bool get_signal(struct ksignal *ksig)
2676{
2677 struct sighand_struct *sighand = current->sighand;
2678 struct signal_struct *signal = current->signal;
2679 int signr;
2680
2681 clear_notify_signal();
2682 if (unlikely(task_work_pending(current)))
2683 task_work_run();
2684
2685 if (!task_sigpending(current))
2686 return false;
2687
2688 if (unlikely(uprobe_deny_signal()))
2689 return false;
2690
2691 /*
2692 * Do this once, we can't return to user-mode if freezing() == T.
2693 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2694 * thus do not need another check after return.
2695 */
2696 try_to_freeze();
2697
2698relock:
2699 spin_lock_irq(&sighand->siglock);
2700
2701 /*
2702 * Every stopped thread goes here after wakeup. Check to see if
2703 * we should notify the parent, prepare_signal(SIGCONT) encodes
2704 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2705 */
2706 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2707 int why;
2708
2709 if (signal->flags & SIGNAL_CLD_CONTINUED)
2710 why = CLD_CONTINUED;
2711 else
2712 why = CLD_STOPPED;
2713
2714 signal->flags &= ~SIGNAL_CLD_MASK;
2715
2716 spin_unlock_irq(&sighand->siglock);
2717
2718 /*
2719 * Notify the parent that we're continuing. This event is
2720 * always per-process and doesn't make whole lot of sense
2721 * for ptracers, who shouldn't consume the state via
2722 * wait(2) either, but, for backward compatibility, notify
2723 * the ptracer of the group leader too unless it's gonna be
2724 * a duplicate.
2725 */
2726 read_lock(&tasklist_lock);
2727 do_notify_parent_cldstop(current, false, why);
2728
2729 if (ptrace_reparented(current->group_leader))
2730 do_notify_parent_cldstop(current->group_leader,
2731 true, why);
2732 read_unlock(&tasklist_lock);
2733
2734 goto relock;
2735 }
2736
2737 for (;;) {
2738 struct k_sigaction *ka;
2739 enum pid_type type;
2740
2741 /* Has this task already been marked for death? */
2742 if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2743 signal->group_exec_task) {
2744 signr = SIGKILL;
2745 sigdelset(¤t->pending.signal, SIGKILL);
2746 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2747 &sighand->action[SIGKILL-1]);
2748 recalc_sigpending();
2749 /*
2750 * implies do_group_exit() or return to PF_USER_WORKER,
2751 * no need to initialize ksig->info/etc.
2752 */
2753 goto fatal;
2754 }
2755
2756 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2757 do_signal_stop(0))
2758 goto relock;
2759
2760 if (unlikely(current->jobctl &
2761 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2762 if (current->jobctl & JOBCTL_TRAP_MASK) {
2763 do_jobctl_trap();
2764 spin_unlock_irq(&sighand->siglock);
2765 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2766 do_freezer_trap();
2767
2768 goto relock;
2769 }
2770
2771 /*
2772 * If the task is leaving the frozen state, let's update
2773 * cgroup counters and reset the frozen bit.
2774 */
2775 if (unlikely(cgroup_task_frozen(current))) {
2776 spin_unlock_irq(&sighand->siglock);
2777 cgroup_leave_frozen(false);
2778 goto relock;
2779 }
2780
2781 /*
2782 * Signals generated by the execution of an instruction
2783 * need to be delivered before any other pending signals
2784 * so that the instruction pointer in the signal stack
2785 * frame points to the faulting instruction.
2786 */
2787 type = PIDTYPE_PID;
2788 signr = dequeue_synchronous_signal(&ksig->info);
2789 if (!signr)
2790 signr = dequeue_signal(current, ¤t->blocked,
2791 &ksig->info, &type);
2792
2793 if (!signr)
2794 break; /* will return 0 */
2795
2796 if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2797 !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2798 signr = ptrace_signal(signr, &ksig->info, type);
2799 if (!signr)
2800 continue;
2801 }
2802
2803 ka = &sighand->action[signr-1];
2804
2805 /* Trace actually delivered signals. */
2806 trace_signal_deliver(signr, &ksig->info, ka);
2807
2808 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2809 continue;
2810 if (ka->sa.sa_handler != SIG_DFL) {
2811 /* Run the handler. */
2812 ksig->ka = *ka;
2813
2814 if (ka->sa.sa_flags & SA_ONESHOT)
2815 ka->sa.sa_handler = SIG_DFL;
2816
2817 break; /* will return non-zero "signr" value */
2818 }
2819
2820 /*
2821 * Now we are doing the default action for this signal.
2822 */
2823 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2824 continue;
2825
2826 /*
2827 * Global init gets no signals it doesn't want.
2828 * Container-init gets no signals it doesn't want from same
2829 * container.
2830 *
2831 * Note that if global/container-init sees a sig_kernel_only()
2832 * signal here, the signal must have been generated internally
2833 * or must have come from an ancestor namespace. In either
2834 * case, the signal cannot be dropped.
2835 */
2836 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2837 !sig_kernel_only(signr))
2838 continue;
2839
2840 if (sig_kernel_stop(signr)) {
2841 /*
2842 * The default action is to stop all threads in
2843 * the thread group. The job control signals
2844 * do nothing in an orphaned pgrp, but SIGSTOP
2845 * always works. Note that siglock needs to be
2846 * dropped during the call to is_orphaned_pgrp()
2847 * because of lock ordering with tasklist_lock.
2848 * This allows an intervening SIGCONT to be posted.
2849 * We need to check for that and bail out if necessary.
2850 */
2851 if (signr != SIGSTOP) {
2852 spin_unlock_irq(&sighand->siglock);
2853
2854 /* signals can be posted during this window */
2855
2856 if (is_current_pgrp_orphaned())
2857 goto relock;
2858
2859 spin_lock_irq(&sighand->siglock);
2860 }
2861
2862 if (likely(do_signal_stop(signr))) {
2863 /* It released the siglock. */
2864 goto relock;
2865 }
2866
2867 /*
2868 * We didn't actually stop, due to a race
2869 * with SIGCONT or something like that.
2870 */
2871 continue;
2872 }
2873
2874 fatal:
2875 spin_unlock_irq(&sighand->siglock);
2876 if (unlikely(cgroup_task_frozen(current)))
2877 cgroup_leave_frozen(true);
2878
2879 /*
2880 * Anything else is fatal, maybe with a core dump.
2881 */
2882 current->flags |= PF_SIGNALED;
2883
2884 if (sig_kernel_coredump(signr)) {
2885 if (print_fatal_signals)
2886 print_fatal_signal(signr);
2887 proc_coredump_connector(current);
2888 /*
2889 * If it was able to dump core, this kills all
2890 * other threads in the group and synchronizes with
2891 * their demise. If we lost the race with another
2892 * thread getting here, it set group_exit_code
2893 * first and our do_group_exit call below will use
2894 * that value and ignore the one we pass it.
2895 */
2896 do_coredump(&ksig->info);
2897 }
2898
2899 /*
2900 * PF_USER_WORKER threads will catch and exit on fatal signals
2901 * themselves. They have cleanup that must be performed, so we
2902 * cannot call do_exit() on their behalf. Note that ksig won't
2903 * be properly initialized, PF_USER_WORKER's shouldn't use it.
2904 */
2905 if (current->flags & PF_USER_WORKER)
2906 goto out;
2907
2908 /*
2909 * Death signals, no core dump.
2910 */
2911 do_group_exit(signr);
2912 /* NOTREACHED */
2913 }
2914 spin_unlock_irq(&sighand->siglock);
2915
2916 ksig->sig = signr;
2917
2918 if (signr && !(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2919 hide_si_addr_tag_bits(ksig);
2920out:
2921 return signr > 0;
2922}
2923
2924/**
2925 * signal_delivered - called after signal delivery to update blocked signals
2926 * @ksig: kernel signal struct
2927 * @stepping: nonzero if debugger single-step or block-step in use
2928 *
2929 * This function should be called when a signal has successfully been
2930 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2931 * is always blocked), and the signal itself is blocked unless %SA_NODEFER
2932 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2933 */
2934static void signal_delivered(struct ksignal *ksig, int stepping)
2935{
2936 sigset_t blocked;
2937
2938 /* A signal was successfully delivered, and the
2939 saved sigmask was stored on the signal frame,
2940 and will be restored by sigreturn. So we can
2941 simply clear the restore sigmask flag. */
2942 clear_restore_sigmask();
2943
2944 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2945 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2946 sigaddset(&blocked, ksig->sig);
2947 set_current_blocked(&blocked);
2948 if (current->sas_ss_flags & SS_AUTODISARM)
2949 sas_ss_reset(current);
2950 if (stepping)
2951 ptrace_notify(SIGTRAP, 0);
2952}
2953
2954void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2955{
2956 if (failed)
2957 force_sigsegv(ksig->sig);
2958 else
2959 signal_delivered(ksig, stepping);
2960}
2961
2962/*
2963 * It could be that complete_signal() picked us to notify about the
2964 * group-wide signal. Other threads should be notified now to take
2965 * the shared signals in @which since we will not.
2966 */
2967static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2968{
2969 sigset_t retarget;
2970 struct task_struct *t;
2971
2972 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2973 if (sigisemptyset(&retarget))
2974 return;
2975
2976 for_other_threads(tsk, t) {
2977 if (t->flags & PF_EXITING)
2978 continue;
2979
2980 if (!has_pending_signals(&retarget, &t->blocked))
2981 continue;
2982 /* Remove the signals this thread can handle. */
2983 sigandsets(&retarget, &retarget, &t->blocked);
2984
2985 if (!task_sigpending(t))
2986 signal_wake_up(t, 0);
2987
2988 if (sigisemptyset(&retarget))
2989 break;
2990 }
2991}
2992
2993void exit_signals(struct task_struct *tsk)
2994{
2995 int group_stop = 0;
2996 sigset_t unblocked;
2997
2998 /*
2999 * @tsk is about to have PF_EXITING set - lock out users which
3000 * expect stable threadgroup.
3001 */
3002 cgroup_threadgroup_change_begin(tsk);
3003
3004 if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
3005 sched_mm_cid_exit_signals(tsk);
3006 tsk->flags |= PF_EXITING;
3007 cgroup_threadgroup_change_end(tsk);
3008 return;
3009 }
3010
3011 spin_lock_irq(&tsk->sighand->siglock);
3012 /*
3013 * From now this task is not visible for group-wide signals,
3014 * see wants_signal(), do_signal_stop().
3015 */
3016 sched_mm_cid_exit_signals(tsk);
3017 tsk->flags |= PF_EXITING;
3018
3019 cgroup_threadgroup_change_end(tsk);
3020
3021 if (!task_sigpending(tsk))
3022 goto out;
3023
3024 unblocked = tsk->blocked;
3025 signotset(&unblocked);
3026 retarget_shared_pending(tsk, &unblocked);
3027
3028 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3029 task_participate_group_stop(tsk))
3030 group_stop = CLD_STOPPED;
3031out:
3032 spin_unlock_irq(&tsk->sighand->siglock);
3033
3034 /*
3035 * If group stop has completed, deliver the notification. This
3036 * should always go to the real parent of the group leader.
3037 */
3038 if (unlikely(group_stop)) {
3039 read_lock(&tasklist_lock);
3040 do_notify_parent_cldstop(tsk, false, group_stop);
3041 read_unlock(&tasklist_lock);
3042 }
3043}
3044
3045/*
3046 * System call entry points.
3047 */
3048
3049/**
3050 * sys_restart_syscall - restart a system call
3051 */
3052SYSCALL_DEFINE0(restart_syscall)
3053{
3054 struct restart_block *restart = ¤t->restart_block;
3055 return restart->fn(restart);
3056}
3057
3058long do_no_restart_syscall(struct restart_block *param)
3059{
3060 return -EINTR;
3061}
3062
3063static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3064{
3065 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
3066 sigset_t newblocked;
3067 /* A set of now blocked but previously unblocked signals. */
3068 sigandnsets(&newblocked, newset, ¤t->blocked);
3069 retarget_shared_pending(tsk, &newblocked);
3070 }
3071 tsk->blocked = *newset;
3072 recalc_sigpending();
3073}
3074
3075/**
3076 * set_current_blocked - change current->blocked mask
3077 * @newset: new mask
3078 *
3079 * It is wrong to change ->blocked directly, this helper should be used
3080 * to ensure the process can't miss a shared signal we are going to block.
3081 */
3082void set_current_blocked(sigset_t *newset)
3083{
3084 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3085 __set_current_blocked(newset);
3086}
3087
3088void __set_current_blocked(const sigset_t *newset)
3089{
3090 struct task_struct *tsk = current;
3091
3092 /*
3093 * In case the signal mask hasn't changed, there is nothing we need
3094 * to do. The current->blocked shouldn't be modified by other task.
3095 */
3096 if (sigequalsets(&tsk->blocked, newset))
3097 return;
3098
3099 spin_lock_irq(&tsk->sighand->siglock);
3100 __set_task_blocked(tsk, newset);
3101 spin_unlock_irq(&tsk->sighand->siglock);
3102}
3103
3104/*
3105 * This is also useful for kernel threads that want to temporarily
3106 * (or permanently) block certain signals.
3107 *
3108 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3109 * interface happily blocks "unblockable" signals like SIGKILL
3110 * and friends.
3111 */
3112int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3113{
3114 struct task_struct *tsk = current;
3115 sigset_t newset;
3116
3117 /* Lockless, only current can change ->blocked, never from irq */
3118 if (oldset)
3119 *oldset = tsk->blocked;
3120
3121 switch (how) {
3122 case SIG_BLOCK:
3123 sigorsets(&newset, &tsk->blocked, set);
3124 break;
3125 case SIG_UNBLOCK:
3126 sigandnsets(&newset, &tsk->blocked, set);
3127 break;
3128 case SIG_SETMASK:
3129 newset = *set;
3130 break;
3131 default:
3132 return -EINVAL;
3133 }
3134
3135 __set_current_blocked(&newset);
3136 return 0;
3137}
3138EXPORT_SYMBOL(sigprocmask);
3139
3140/*
3141 * The api helps set app-provided sigmasks.
3142 *
3143 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3144 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3145 *
3146 * Note that it does set_restore_sigmask() in advance, so it must be always
3147 * paired with restore_saved_sigmask_unless() before return from syscall.
3148 */
3149int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3150{
3151 sigset_t kmask;
3152
3153 if (!umask)
3154 return 0;
3155 if (sigsetsize != sizeof(sigset_t))
3156 return -EINVAL;
3157 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3158 return -EFAULT;
3159
3160 set_restore_sigmask();
3161 current->saved_sigmask = current->blocked;
3162 set_current_blocked(&kmask);
3163
3164 return 0;
3165}
3166
3167#ifdef CONFIG_COMPAT
3168int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3169 size_t sigsetsize)
3170{
3171 sigset_t kmask;
3172
3173 if (!umask)
3174 return 0;
3175 if (sigsetsize != sizeof(compat_sigset_t))
3176 return -EINVAL;
3177 if (get_compat_sigset(&kmask, umask))
3178 return -EFAULT;
3179
3180 set_restore_sigmask();
3181 current->saved_sigmask = current->blocked;
3182 set_current_blocked(&kmask);
3183
3184 return 0;
3185}
3186#endif
3187
3188/**
3189 * sys_rt_sigprocmask - change the list of currently blocked signals
3190 * @how: whether to add, remove, or set signals
3191 * @nset: stores pending signals
3192 * @oset: previous value of signal mask if non-null
3193 * @sigsetsize: size of sigset_t type
3194 */
3195SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3196 sigset_t __user *, oset, size_t, sigsetsize)
3197{
3198 sigset_t old_set, new_set;
3199 int error;
3200
3201 /* XXX: Don't preclude handling different sized sigset_t's. */
3202 if (sigsetsize != sizeof(sigset_t))
3203 return -EINVAL;
3204
3205 old_set = current->blocked;
3206
3207 if (nset) {
3208 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3209 return -EFAULT;
3210 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3211
3212 error = sigprocmask(how, &new_set, NULL);
3213 if (error)
3214 return error;
3215 }
3216
3217 if (oset) {
3218 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3219 return -EFAULT;
3220 }
3221
3222 return 0;
3223}
3224
3225#ifdef CONFIG_COMPAT
3226COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3227 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3228{
3229 sigset_t old_set = current->blocked;
3230
3231 /* XXX: Don't preclude handling different sized sigset_t's. */
3232 if (sigsetsize != sizeof(sigset_t))
3233 return -EINVAL;
3234
3235 if (nset) {
3236 sigset_t new_set;
3237 int error;
3238 if (get_compat_sigset(&new_set, nset))
3239 return -EFAULT;
3240 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3241
3242 error = sigprocmask(how, &new_set, NULL);
3243 if (error)
3244 return error;
3245 }
3246 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3247}
3248#endif
3249
3250static void do_sigpending(sigset_t *set)
3251{
3252 spin_lock_irq(¤t->sighand->siglock);
3253 sigorsets(set, ¤t->pending.signal,
3254 ¤t->signal->shared_pending.signal);
3255 spin_unlock_irq(¤t->sighand->siglock);
3256
3257 /* Outside the lock because only this thread touches it. */
3258 sigandsets(set, ¤t->blocked, set);
3259}
3260
3261/**
3262 * sys_rt_sigpending - examine a pending signal that has been raised
3263 * while blocked
3264 * @uset: stores pending signals
3265 * @sigsetsize: size of sigset_t type or larger
3266 */
3267SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3268{
3269 sigset_t set;
3270
3271 if (sigsetsize > sizeof(*uset))
3272 return -EINVAL;
3273
3274 do_sigpending(&set);
3275
3276 if (copy_to_user(uset, &set, sigsetsize))
3277 return -EFAULT;
3278
3279 return 0;
3280}
3281
3282#ifdef CONFIG_COMPAT
3283COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3284 compat_size_t, sigsetsize)
3285{
3286 sigset_t set;
3287
3288 if (sigsetsize > sizeof(*uset))
3289 return -EINVAL;
3290
3291 do_sigpending(&set);
3292
3293 return put_compat_sigset(uset, &set, sigsetsize);
3294}
3295#endif
3296
3297static const struct {
3298 unsigned char limit, layout;
3299} sig_sicodes[] = {
3300 [SIGILL] = { NSIGILL, SIL_FAULT },
3301 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3302 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3303 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3304 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3305#if defined(SIGEMT)
3306 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3307#endif
3308 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3309 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3310 [SIGSYS] = { NSIGSYS, SIL_SYS },
3311};
3312
3313static bool known_siginfo_layout(unsigned sig, int si_code)
3314{
3315 if (si_code == SI_KERNEL)
3316 return true;
3317 else if ((si_code > SI_USER)) {
3318 if (sig_specific_sicodes(sig)) {
3319 if (si_code <= sig_sicodes[sig].limit)
3320 return true;
3321 }
3322 else if (si_code <= NSIGPOLL)
3323 return true;
3324 }
3325 else if (si_code >= SI_DETHREAD)
3326 return true;
3327 else if (si_code == SI_ASYNCNL)
3328 return true;
3329 return false;
3330}
3331
3332enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3333{
3334 enum siginfo_layout layout = SIL_KILL;
3335 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3336 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3337 (si_code <= sig_sicodes[sig].limit)) {
3338 layout = sig_sicodes[sig].layout;
3339 /* Handle the exceptions */
3340 if ((sig == SIGBUS) &&
3341 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3342 layout = SIL_FAULT_MCEERR;
3343 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3344 layout = SIL_FAULT_BNDERR;
3345#ifdef SEGV_PKUERR
3346 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3347 layout = SIL_FAULT_PKUERR;
3348#endif
3349 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3350 layout = SIL_FAULT_PERF_EVENT;
3351 else if (IS_ENABLED(CONFIG_SPARC) &&
3352 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3353 layout = SIL_FAULT_TRAPNO;
3354 else if (IS_ENABLED(CONFIG_ALPHA) &&
3355 ((sig == SIGFPE) ||
3356 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3357 layout = SIL_FAULT_TRAPNO;
3358 }
3359 else if (si_code <= NSIGPOLL)
3360 layout = SIL_POLL;
3361 } else {
3362 if (si_code == SI_TIMER)
3363 layout = SIL_TIMER;
3364 else if (si_code == SI_SIGIO)
3365 layout = SIL_POLL;
3366 else if (si_code < 0)
3367 layout = SIL_RT;
3368 }
3369 return layout;
3370}
3371
3372static inline char __user *si_expansion(const siginfo_t __user *info)
3373{
3374 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3375}
3376
3377int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3378{
3379 char __user *expansion = si_expansion(to);
3380 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3381 return -EFAULT;
3382 if (clear_user(expansion, SI_EXPANSION_SIZE))
3383 return -EFAULT;
3384 return 0;
3385}
3386
3387static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3388 const siginfo_t __user *from)
3389{
3390 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3391 char __user *expansion = si_expansion(from);
3392 char buf[SI_EXPANSION_SIZE];
3393 int i;
3394 /*
3395 * An unknown si_code might need more than
3396 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3397 * extra bytes are 0. This guarantees copy_siginfo_to_user
3398 * will return this data to userspace exactly.
3399 */
3400 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3401 return -EFAULT;
3402 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3403 if (buf[i] != 0)
3404 return -E2BIG;
3405 }
3406 }
3407 return 0;
3408}
3409
3410static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3411 const siginfo_t __user *from)
3412{
3413 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3414 return -EFAULT;
3415 to->si_signo = signo;
3416 return post_copy_siginfo_from_user(to, from);
3417}
3418
3419int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3420{
3421 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3422 return -EFAULT;
3423 return post_copy_siginfo_from_user(to, from);
3424}
3425
3426#ifdef CONFIG_COMPAT
3427/**
3428 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3429 * @to: compat siginfo destination
3430 * @from: kernel siginfo source
3431 *
3432 * Note: This function does not work properly for the SIGCHLD on x32, but
3433 * fortunately it doesn't have to. The only valid callers for this function are
3434 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3435 * The latter does not care because SIGCHLD will never cause a coredump.
3436 */
3437void copy_siginfo_to_external32(struct compat_siginfo *to,
3438 const struct kernel_siginfo *from)
3439{
3440 memset(to, 0, sizeof(*to));
3441
3442 to->si_signo = from->si_signo;
3443 to->si_errno = from->si_errno;
3444 to->si_code = from->si_code;
3445 switch(siginfo_layout(from->si_signo, from->si_code)) {
3446 case SIL_KILL:
3447 to->si_pid = from->si_pid;
3448 to->si_uid = from->si_uid;
3449 break;
3450 case SIL_TIMER:
3451 to->si_tid = from->si_tid;
3452 to->si_overrun = from->si_overrun;
3453 to->si_int = from->si_int;
3454 break;
3455 case SIL_POLL:
3456 to->si_band = from->si_band;
3457 to->si_fd = from->si_fd;
3458 break;
3459 case SIL_FAULT:
3460 to->si_addr = ptr_to_compat(from->si_addr);
3461 break;
3462 case SIL_FAULT_TRAPNO:
3463 to->si_addr = ptr_to_compat(from->si_addr);
3464 to->si_trapno = from->si_trapno;
3465 break;
3466 case SIL_FAULT_MCEERR:
3467 to->si_addr = ptr_to_compat(from->si_addr);
3468 to->si_addr_lsb = from->si_addr_lsb;
3469 break;
3470 case SIL_FAULT_BNDERR:
3471 to->si_addr = ptr_to_compat(from->si_addr);
3472 to->si_lower = ptr_to_compat(from->si_lower);
3473 to->si_upper = ptr_to_compat(from->si_upper);
3474 break;
3475 case SIL_FAULT_PKUERR:
3476 to->si_addr = ptr_to_compat(from->si_addr);
3477 to->si_pkey = from->si_pkey;
3478 break;
3479 case SIL_FAULT_PERF_EVENT:
3480 to->si_addr = ptr_to_compat(from->si_addr);
3481 to->si_perf_data = from->si_perf_data;
3482 to->si_perf_type = from->si_perf_type;
3483 to->si_perf_flags = from->si_perf_flags;
3484 break;
3485 case SIL_CHLD:
3486 to->si_pid = from->si_pid;
3487 to->si_uid = from->si_uid;
3488 to->si_status = from->si_status;
3489 to->si_utime = from->si_utime;
3490 to->si_stime = from->si_stime;
3491 break;
3492 case SIL_RT:
3493 to->si_pid = from->si_pid;
3494 to->si_uid = from->si_uid;
3495 to->si_int = from->si_int;
3496 break;
3497 case SIL_SYS:
3498 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3499 to->si_syscall = from->si_syscall;
3500 to->si_arch = from->si_arch;
3501 break;
3502 }
3503}
3504
3505int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3506 const struct kernel_siginfo *from)
3507{
3508 struct compat_siginfo new;
3509
3510 copy_siginfo_to_external32(&new, from);
3511 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3512 return -EFAULT;
3513 return 0;
3514}
3515
3516static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3517 const struct compat_siginfo *from)
3518{
3519 clear_siginfo(to);
3520 to->si_signo = from->si_signo;
3521 to->si_errno = from->si_errno;
3522 to->si_code = from->si_code;
3523 switch(siginfo_layout(from->si_signo, from->si_code)) {
3524 case SIL_KILL:
3525 to->si_pid = from->si_pid;
3526 to->si_uid = from->si_uid;
3527 break;
3528 case SIL_TIMER:
3529 to->si_tid = from->si_tid;
3530 to->si_overrun = from->si_overrun;
3531 to->si_int = from->si_int;
3532 break;
3533 case SIL_POLL:
3534 to->si_band = from->si_band;
3535 to->si_fd = from->si_fd;
3536 break;
3537 case SIL_FAULT:
3538 to->si_addr = compat_ptr(from->si_addr);
3539 break;
3540 case SIL_FAULT_TRAPNO:
3541 to->si_addr = compat_ptr(from->si_addr);
3542 to->si_trapno = from->si_trapno;
3543 break;
3544 case SIL_FAULT_MCEERR:
3545 to->si_addr = compat_ptr(from->si_addr);
3546 to->si_addr_lsb = from->si_addr_lsb;
3547 break;
3548 case SIL_FAULT_BNDERR:
3549 to->si_addr = compat_ptr(from->si_addr);
3550 to->si_lower = compat_ptr(from->si_lower);
3551 to->si_upper = compat_ptr(from->si_upper);
3552 break;
3553 case SIL_FAULT_PKUERR:
3554 to->si_addr = compat_ptr(from->si_addr);
3555 to->si_pkey = from->si_pkey;
3556 break;
3557 case SIL_FAULT_PERF_EVENT:
3558 to->si_addr = compat_ptr(from->si_addr);
3559 to->si_perf_data = from->si_perf_data;
3560 to->si_perf_type = from->si_perf_type;
3561 to->si_perf_flags = from->si_perf_flags;
3562 break;
3563 case SIL_CHLD:
3564 to->si_pid = from->si_pid;
3565 to->si_uid = from->si_uid;
3566 to->si_status = from->si_status;
3567#ifdef CONFIG_X86_X32_ABI
3568 if (in_x32_syscall()) {
3569 to->si_utime = from->_sifields._sigchld_x32._utime;
3570 to->si_stime = from->_sifields._sigchld_x32._stime;
3571 } else
3572#endif
3573 {
3574 to->si_utime = from->si_utime;
3575 to->si_stime = from->si_stime;
3576 }
3577 break;
3578 case SIL_RT:
3579 to->si_pid = from->si_pid;
3580 to->si_uid = from->si_uid;
3581 to->si_int = from->si_int;
3582 break;
3583 case SIL_SYS:
3584 to->si_call_addr = compat_ptr(from->si_call_addr);
3585 to->si_syscall = from->si_syscall;
3586 to->si_arch = from->si_arch;
3587 break;
3588 }
3589 return 0;
3590}
3591
3592static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3593 const struct compat_siginfo __user *ufrom)
3594{
3595 struct compat_siginfo from;
3596
3597 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3598 return -EFAULT;
3599
3600 from.si_signo = signo;
3601 return post_copy_siginfo_from_user32(to, &from);
3602}
3603
3604int copy_siginfo_from_user32(struct kernel_siginfo *to,
3605 const struct compat_siginfo __user *ufrom)
3606{
3607 struct compat_siginfo from;
3608
3609 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3610 return -EFAULT;
3611
3612 return post_copy_siginfo_from_user32(to, &from);
3613}
3614#endif /* CONFIG_COMPAT */
3615
3616/**
3617 * do_sigtimedwait - wait for queued signals specified in @which
3618 * @which: queued signals to wait for
3619 * @info: if non-null, the signal's siginfo is returned here
3620 * @ts: upper bound on process time suspension
3621 */
3622static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3623 const struct timespec64 *ts)
3624{
3625 ktime_t *to = NULL, timeout = KTIME_MAX;
3626 struct task_struct *tsk = current;
3627 sigset_t mask = *which;
3628 enum pid_type type;
3629 int sig, ret = 0;
3630
3631 if (ts) {
3632 if (!timespec64_valid(ts))
3633 return -EINVAL;
3634 timeout = timespec64_to_ktime(*ts);
3635 to = &timeout;
3636 }
3637
3638 /*
3639 * Invert the set of allowed signals to get those we want to block.
3640 */
3641 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3642 signotset(&mask);
3643
3644 spin_lock_irq(&tsk->sighand->siglock);
3645 sig = dequeue_signal(tsk, &mask, info, &type);
3646 if (!sig && timeout) {
3647 /*
3648 * None ready, temporarily unblock those we're interested
3649 * while we are sleeping in so that we'll be awakened when
3650 * they arrive. Unblocking is always fine, we can avoid
3651 * set_current_blocked().
3652 */
3653 tsk->real_blocked = tsk->blocked;
3654 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3655 recalc_sigpending();
3656 spin_unlock_irq(&tsk->sighand->siglock);
3657
3658 __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3659 ret = schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3660 HRTIMER_MODE_REL);
3661 spin_lock_irq(&tsk->sighand->siglock);
3662 __set_task_blocked(tsk, &tsk->real_blocked);
3663 sigemptyset(&tsk->real_blocked);
3664 sig = dequeue_signal(tsk, &mask, info, &type);
3665 }
3666 spin_unlock_irq(&tsk->sighand->siglock);
3667
3668 if (sig)
3669 return sig;
3670 return ret ? -EINTR : -EAGAIN;
3671}
3672
3673/**
3674 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3675 * in @uthese
3676 * @uthese: queued signals to wait for
3677 * @uinfo: if non-null, the signal's siginfo is returned here
3678 * @uts: upper bound on process time suspension
3679 * @sigsetsize: size of sigset_t type
3680 */
3681SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3682 siginfo_t __user *, uinfo,
3683 const struct __kernel_timespec __user *, uts,
3684 size_t, sigsetsize)
3685{
3686 sigset_t these;
3687 struct timespec64 ts;
3688 kernel_siginfo_t info;
3689 int ret;
3690
3691 /* XXX: Don't preclude handling different sized sigset_t's. */
3692 if (sigsetsize != sizeof(sigset_t))
3693 return -EINVAL;
3694
3695 if (copy_from_user(&these, uthese, sizeof(these)))
3696 return -EFAULT;
3697
3698 if (uts) {
3699 if (get_timespec64(&ts, uts))
3700 return -EFAULT;
3701 }
3702
3703 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3704
3705 if (ret > 0 && uinfo) {
3706 if (copy_siginfo_to_user(uinfo, &info))
3707 ret = -EFAULT;
3708 }
3709
3710 return ret;
3711}
3712
3713#ifdef CONFIG_COMPAT_32BIT_TIME
3714SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3715 siginfo_t __user *, uinfo,
3716 const struct old_timespec32 __user *, uts,
3717 size_t, sigsetsize)
3718{
3719 sigset_t these;
3720 struct timespec64 ts;
3721 kernel_siginfo_t info;
3722 int ret;
3723
3724 if (sigsetsize != sizeof(sigset_t))
3725 return -EINVAL;
3726
3727 if (copy_from_user(&these, uthese, sizeof(these)))
3728 return -EFAULT;
3729
3730 if (uts) {
3731 if (get_old_timespec32(&ts, uts))
3732 return -EFAULT;
3733 }
3734
3735 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3736
3737 if (ret > 0 && uinfo) {
3738 if (copy_siginfo_to_user(uinfo, &info))
3739 ret = -EFAULT;
3740 }
3741
3742 return ret;
3743}
3744#endif
3745
3746#ifdef CONFIG_COMPAT
3747COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3748 struct compat_siginfo __user *, uinfo,
3749 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3750{
3751 sigset_t s;
3752 struct timespec64 t;
3753 kernel_siginfo_t info;
3754 long ret;
3755
3756 if (sigsetsize != sizeof(sigset_t))
3757 return -EINVAL;
3758
3759 if (get_compat_sigset(&s, uthese))
3760 return -EFAULT;
3761
3762 if (uts) {
3763 if (get_timespec64(&t, uts))
3764 return -EFAULT;
3765 }
3766
3767 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3768
3769 if (ret > 0 && uinfo) {
3770 if (copy_siginfo_to_user32(uinfo, &info))
3771 ret = -EFAULT;
3772 }
3773
3774 return ret;
3775}
3776
3777#ifdef CONFIG_COMPAT_32BIT_TIME
3778COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3779 struct compat_siginfo __user *, uinfo,
3780 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3781{
3782 sigset_t s;
3783 struct timespec64 t;
3784 kernel_siginfo_t info;
3785 long ret;
3786
3787 if (sigsetsize != sizeof(sigset_t))
3788 return -EINVAL;
3789
3790 if (get_compat_sigset(&s, uthese))
3791 return -EFAULT;
3792
3793 if (uts) {
3794 if (get_old_timespec32(&t, uts))
3795 return -EFAULT;
3796 }
3797
3798 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3799
3800 if (ret > 0 && uinfo) {
3801 if (copy_siginfo_to_user32(uinfo, &info))
3802 ret = -EFAULT;
3803 }
3804
3805 return ret;
3806}
3807#endif
3808#endif
3809
3810static void prepare_kill_siginfo(int sig, struct kernel_siginfo *info,
3811 enum pid_type type)
3812{
3813 clear_siginfo(info);
3814 info->si_signo = sig;
3815 info->si_errno = 0;
3816 info->si_code = (type == PIDTYPE_PID) ? SI_TKILL : SI_USER;
3817 info->si_pid = task_tgid_vnr(current);
3818 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3819}
3820
3821/**
3822 * sys_kill - send a signal to a process
3823 * @pid: the PID of the process
3824 * @sig: signal to be sent
3825 */
3826SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3827{
3828 struct kernel_siginfo info;
3829
3830 prepare_kill_siginfo(sig, &info, PIDTYPE_TGID);
3831
3832 return kill_something_info(sig, &info, pid);
3833}
3834
3835/*
3836 * Verify that the signaler and signalee either are in the same pid namespace
3837 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3838 * namespace.
3839 */
3840static bool access_pidfd_pidns(struct pid *pid)
3841{
3842 struct pid_namespace *active = task_active_pid_ns(current);
3843 struct pid_namespace *p = ns_of_pid(pid);
3844
3845 for (;;) {
3846 if (!p)
3847 return false;
3848 if (p == active)
3849 break;
3850 p = p->parent;
3851 }
3852
3853 return true;
3854}
3855
3856static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3857 siginfo_t __user *info)
3858{
3859#ifdef CONFIG_COMPAT
3860 /*
3861 * Avoid hooking up compat syscalls and instead handle necessary
3862 * conversions here. Note, this is a stop-gap measure and should not be
3863 * considered a generic solution.
3864 */
3865 if (in_compat_syscall())
3866 return copy_siginfo_from_user32(
3867 kinfo, (struct compat_siginfo __user *)info);
3868#endif
3869 return copy_siginfo_from_user(kinfo, info);
3870}
3871
3872static struct pid *pidfd_to_pid(const struct file *file)
3873{
3874 struct pid *pid;
3875
3876 pid = pidfd_pid(file);
3877 if (!IS_ERR(pid))
3878 return pid;
3879
3880 return tgid_pidfd_to_pid(file);
3881}
3882
3883#define PIDFD_SEND_SIGNAL_FLAGS \
3884 (PIDFD_SIGNAL_THREAD | PIDFD_SIGNAL_THREAD_GROUP | \
3885 PIDFD_SIGNAL_PROCESS_GROUP)
3886
3887/**
3888 * sys_pidfd_send_signal - Signal a process through a pidfd
3889 * @pidfd: file descriptor of the process
3890 * @sig: signal to send
3891 * @info: signal info
3892 * @flags: future flags
3893 *
3894 * Send the signal to the thread group or to the individual thread depending
3895 * on PIDFD_THREAD.
3896 * In the future extension to @flags may be used to override the default scope
3897 * of @pidfd.
3898 *
3899 * Return: 0 on success, negative errno on failure
3900 */
3901SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3902 siginfo_t __user *, info, unsigned int, flags)
3903{
3904 int ret;
3905 struct fd f;
3906 struct pid *pid;
3907 kernel_siginfo_t kinfo;
3908 enum pid_type type;
3909
3910 /* Enforce flags be set to 0 until we add an extension. */
3911 if (flags & ~PIDFD_SEND_SIGNAL_FLAGS)
3912 return -EINVAL;
3913
3914 /* Ensure that only a single signal scope determining flag is set. */
3915 if (hweight32(flags & PIDFD_SEND_SIGNAL_FLAGS) > 1)
3916 return -EINVAL;
3917
3918 f = fdget(pidfd);
3919 if (!f.file)
3920 return -EBADF;
3921
3922 /* Is this a pidfd? */
3923 pid = pidfd_to_pid(f.file);
3924 if (IS_ERR(pid)) {
3925 ret = PTR_ERR(pid);
3926 goto err;
3927 }
3928
3929 ret = -EINVAL;
3930 if (!access_pidfd_pidns(pid))
3931 goto err;
3932
3933 switch (flags) {
3934 case 0:
3935 /* Infer scope from the type of pidfd. */
3936 if (f.file->f_flags & PIDFD_THREAD)
3937 type = PIDTYPE_PID;
3938 else
3939 type = PIDTYPE_TGID;
3940 break;
3941 case PIDFD_SIGNAL_THREAD:
3942 type = PIDTYPE_PID;
3943 break;
3944 case PIDFD_SIGNAL_THREAD_GROUP:
3945 type = PIDTYPE_TGID;
3946 break;
3947 case PIDFD_SIGNAL_PROCESS_GROUP:
3948 type = PIDTYPE_PGID;
3949 break;
3950 }
3951
3952 if (info) {
3953 ret = copy_siginfo_from_user_any(&kinfo, info);
3954 if (unlikely(ret))
3955 goto err;
3956
3957 ret = -EINVAL;
3958 if (unlikely(sig != kinfo.si_signo))
3959 goto err;
3960
3961 /* Only allow sending arbitrary signals to yourself. */
3962 ret = -EPERM;
3963 if ((task_pid(current) != pid || type > PIDTYPE_TGID) &&
3964 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3965 goto err;
3966 } else {
3967 prepare_kill_siginfo(sig, &kinfo, type);
3968 }
3969
3970 if (type == PIDTYPE_PGID)
3971 ret = kill_pgrp_info(sig, &kinfo, pid);
3972 else
3973 ret = kill_pid_info_type(sig, &kinfo, pid, type);
3974err:
3975 fdput(f);
3976 return ret;
3977}
3978
3979static int
3980do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3981{
3982 struct task_struct *p;
3983 int error = -ESRCH;
3984
3985 rcu_read_lock();
3986 p = find_task_by_vpid(pid);
3987 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3988 error = check_kill_permission(sig, info, p);
3989 /*
3990 * The null signal is a permissions and process existence
3991 * probe. No signal is actually delivered.
3992 */
3993 if (!error && sig) {
3994 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3995 /*
3996 * If lock_task_sighand() failed we pretend the task
3997 * dies after receiving the signal. The window is tiny,
3998 * and the signal is private anyway.
3999 */
4000 if (unlikely(error == -ESRCH))
4001 error = 0;
4002 }
4003 }
4004 rcu_read_unlock();
4005
4006 return error;
4007}
4008
4009static int do_tkill(pid_t tgid, pid_t pid, int sig)
4010{
4011 struct kernel_siginfo info;
4012
4013 prepare_kill_siginfo(sig, &info, PIDTYPE_PID);
4014
4015 return do_send_specific(tgid, pid, sig, &info);
4016}
4017
4018/**
4019 * sys_tgkill - send signal to one specific thread
4020 * @tgid: the thread group ID of the thread
4021 * @pid: the PID of the thread
4022 * @sig: signal to be sent
4023 *
4024 * This syscall also checks the @tgid and returns -ESRCH even if the PID
4025 * exists but it's not belonging to the target process anymore. This
4026 * method solves the problem of threads exiting and PIDs getting reused.
4027 */
4028SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
4029{
4030 /* This is only valid for single tasks */
4031 if (pid <= 0 || tgid <= 0)
4032 return -EINVAL;
4033
4034 return do_tkill(tgid, pid, sig);
4035}
4036
4037/**
4038 * sys_tkill - send signal to one specific task
4039 * @pid: the PID of the task
4040 * @sig: signal to be sent
4041 *
4042 * Send a signal to only one task, even if it's a CLONE_THREAD task.
4043 */
4044SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4045{
4046 /* This is only valid for single tasks */
4047 if (pid <= 0)
4048 return -EINVAL;
4049
4050 return do_tkill(0, pid, sig);
4051}
4052
4053static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4054{
4055 /* Not even root can pretend to send signals from the kernel.
4056 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4057 */
4058 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4059 (task_pid_vnr(current) != pid))
4060 return -EPERM;
4061
4062 /* POSIX.1b doesn't mention process groups. */
4063 return kill_proc_info(sig, info, pid);
4064}
4065
4066/**
4067 * sys_rt_sigqueueinfo - send signal information to a signal
4068 * @pid: the PID of the thread
4069 * @sig: signal to be sent
4070 * @uinfo: signal info to be sent
4071 */
4072SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4073 siginfo_t __user *, uinfo)
4074{
4075 kernel_siginfo_t info;
4076 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4077 if (unlikely(ret))
4078 return ret;
4079 return do_rt_sigqueueinfo(pid, sig, &info);
4080}
4081
4082#ifdef CONFIG_COMPAT
4083COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4084 compat_pid_t, pid,
4085 int, sig,
4086 struct compat_siginfo __user *, uinfo)
4087{
4088 kernel_siginfo_t info;
4089 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4090 if (unlikely(ret))
4091 return ret;
4092 return do_rt_sigqueueinfo(pid, sig, &info);
4093}
4094#endif
4095
4096static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4097{
4098 /* This is only valid for single tasks */
4099 if (pid <= 0 || tgid <= 0)
4100 return -EINVAL;
4101
4102 /* Not even root can pretend to send signals from the kernel.
4103 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4104 */
4105 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4106 (task_pid_vnr(current) != pid))
4107 return -EPERM;
4108
4109 return do_send_specific(tgid, pid, sig, info);
4110}
4111
4112SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4113 siginfo_t __user *, uinfo)
4114{
4115 kernel_siginfo_t info;
4116 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4117 if (unlikely(ret))
4118 return ret;
4119 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4120}
4121
4122#ifdef CONFIG_COMPAT
4123COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4124 compat_pid_t, tgid,
4125 compat_pid_t, pid,
4126 int, sig,
4127 struct compat_siginfo __user *, uinfo)
4128{
4129 kernel_siginfo_t info;
4130 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4131 if (unlikely(ret))
4132 return ret;
4133 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4134}
4135#endif
4136
4137/*
4138 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4139 */
4140void kernel_sigaction(int sig, __sighandler_t action)
4141{
4142 spin_lock_irq(¤t->sighand->siglock);
4143 current->sighand->action[sig - 1].sa.sa_handler = action;
4144 if (action == SIG_IGN) {
4145 sigset_t mask;
4146
4147 sigemptyset(&mask);
4148 sigaddset(&mask, sig);
4149
4150 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4151 flush_sigqueue_mask(&mask, ¤t->pending);
4152 recalc_sigpending();
4153 }
4154 spin_unlock_irq(¤t->sighand->siglock);
4155}
4156EXPORT_SYMBOL(kernel_sigaction);
4157
4158void __weak sigaction_compat_abi(struct k_sigaction *act,
4159 struct k_sigaction *oact)
4160{
4161}
4162
4163int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4164{
4165 struct task_struct *p = current, *t;
4166 struct k_sigaction *k;
4167 sigset_t mask;
4168
4169 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4170 return -EINVAL;
4171
4172 k = &p->sighand->action[sig-1];
4173
4174 spin_lock_irq(&p->sighand->siglock);
4175 if (k->sa.sa_flags & SA_IMMUTABLE) {
4176 spin_unlock_irq(&p->sighand->siglock);
4177 return -EINVAL;
4178 }
4179 if (oact)
4180 *oact = *k;
4181
4182 /*
4183 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4184 * e.g. by having an architecture use the bit in their uapi.
4185 */
4186 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4187
4188 /*
4189 * Clear unknown flag bits in order to allow userspace to detect missing
4190 * support for flag bits and to allow the kernel to use non-uapi bits
4191 * internally.
4192 */
4193 if (act)
4194 act->sa.sa_flags &= UAPI_SA_FLAGS;
4195 if (oact)
4196 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4197
4198 sigaction_compat_abi(act, oact);
4199
4200 if (act) {
4201 sigdelsetmask(&act->sa.sa_mask,
4202 sigmask(SIGKILL) | sigmask(SIGSTOP));
4203 *k = *act;
4204 /*
4205 * POSIX 3.3.1.3:
4206 * "Setting a signal action to SIG_IGN for a signal that is
4207 * pending shall cause the pending signal to be discarded,
4208 * whether or not it is blocked."
4209 *
4210 * "Setting a signal action to SIG_DFL for a signal that is
4211 * pending and whose default action is to ignore the signal
4212 * (for example, SIGCHLD), shall cause the pending signal to
4213 * be discarded, whether or not it is blocked"
4214 */
4215 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4216 sigemptyset(&mask);
4217 sigaddset(&mask, sig);
4218 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4219 for_each_thread(p, t)
4220 flush_sigqueue_mask(&mask, &t->pending);
4221 }
4222 }
4223
4224 spin_unlock_irq(&p->sighand->siglock);
4225 return 0;
4226}
4227
4228#ifdef CONFIG_DYNAMIC_SIGFRAME
4229static inline void sigaltstack_lock(void)
4230 __acquires(¤t->sighand->siglock)
4231{
4232 spin_lock_irq(¤t->sighand->siglock);
4233}
4234
4235static inline void sigaltstack_unlock(void)
4236 __releases(¤t->sighand->siglock)
4237{
4238 spin_unlock_irq(¤t->sighand->siglock);
4239}
4240#else
4241static inline void sigaltstack_lock(void) { }
4242static inline void sigaltstack_unlock(void) { }
4243#endif
4244
4245static int
4246do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4247 size_t min_ss_size)
4248{
4249 struct task_struct *t = current;
4250 int ret = 0;
4251
4252 if (oss) {
4253 memset(oss, 0, sizeof(stack_t));
4254 oss->ss_sp = (void __user *) t->sas_ss_sp;
4255 oss->ss_size = t->sas_ss_size;
4256 oss->ss_flags = sas_ss_flags(sp) |
4257 (current->sas_ss_flags & SS_FLAG_BITS);
4258 }
4259
4260 if (ss) {
4261 void __user *ss_sp = ss->ss_sp;
4262 size_t ss_size = ss->ss_size;
4263 unsigned ss_flags = ss->ss_flags;
4264 int ss_mode;
4265
4266 if (unlikely(on_sig_stack(sp)))
4267 return -EPERM;
4268
4269 ss_mode = ss_flags & ~SS_FLAG_BITS;
4270 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4271 ss_mode != 0))
4272 return -EINVAL;
4273
4274 /*
4275 * Return before taking any locks if no actual
4276 * sigaltstack changes were requested.
4277 */
4278 if (t->sas_ss_sp == (unsigned long)ss_sp &&
4279 t->sas_ss_size == ss_size &&
4280 t->sas_ss_flags == ss_flags)
4281 return 0;
4282
4283 sigaltstack_lock();
4284 if (ss_mode == SS_DISABLE) {
4285 ss_size = 0;
4286 ss_sp = NULL;
4287 } else {
4288 if (unlikely(ss_size < min_ss_size))
4289 ret = -ENOMEM;
4290 if (!sigaltstack_size_valid(ss_size))
4291 ret = -ENOMEM;
4292 }
4293 if (!ret) {
4294 t->sas_ss_sp = (unsigned long) ss_sp;
4295 t->sas_ss_size = ss_size;
4296 t->sas_ss_flags = ss_flags;
4297 }
4298 sigaltstack_unlock();
4299 }
4300 return ret;
4301}
4302
4303SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4304{
4305 stack_t new, old;
4306 int err;
4307 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4308 return -EFAULT;
4309 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4310 current_user_stack_pointer(),
4311 MINSIGSTKSZ);
4312 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4313 err = -EFAULT;
4314 return err;
4315}
4316
4317int restore_altstack(const stack_t __user *uss)
4318{
4319 stack_t new;
4320 if (copy_from_user(&new, uss, sizeof(stack_t)))
4321 return -EFAULT;
4322 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4323 MINSIGSTKSZ);
4324 /* squash all but EFAULT for now */
4325 return 0;
4326}
4327
4328int __save_altstack(stack_t __user *uss, unsigned long sp)
4329{
4330 struct task_struct *t = current;
4331 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4332 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4333 __put_user(t->sas_ss_size, &uss->ss_size);
4334 return err;
4335}
4336
4337#ifdef CONFIG_COMPAT
4338static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4339 compat_stack_t __user *uoss_ptr)
4340{
4341 stack_t uss, uoss;
4342 int ret;
4343
4344 if (uss_ptr) {
4345 compat_stack_t uss32;
4346 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4347 return -EFAULT;
4348 uss.ss_sp = compat_ptr(uss32.ss_sp);
4349 uss.ss_flags = uss32.ss_flags;
4350 uss.ss_size = uss32.ss_size;
4351 }
4352 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4353 compat_user_stack_pointer(),
4354 COMPAT_MINSIGSTKSZ);
4355 if (ret >= 0 && uoss_ptr) {
4356 compat_stack_t old;
4357 memset(&old, 0, sizeof(old));
4358 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4359 old.ss_flags = uoss.ss_flags;
4360 old.ss_size = uoss.ss_size;
4361 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4362 ret = -EFAULT;
4363 }
4364 return ret;
4365}
4366
4367COMPAT_SYSCALL_DEFINE2(sigaltstack,
4368 const compat_stack_t __user *, uss_ptr,
4369 compat_stack_t __user *, uoss_ptr)
4370{
4371 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4372}
4373
4374int compat_restore_altstack(const compat_stack_t __user *uss)
4375{
4376 int err = do_compat_sigaltstack(uss, NULL);
4377 /* squash all but -EFAULT for now */
4378 return err == -EFAULT ? err : 0;
4379}
4380
4381int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4382{
4383 int err;
4384 struct task_struct *t = current;
4385 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4386 &uss->ss_sp) |
4387 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4388 __put_user(t->sas_ss_size, &uss->ss_size);
4389 return err;
4390}
4391#endif
4392
4393#ifdef __ARCH_WANT_SYS_SIGPENDING
4394
4395/**
4396 * sys_sigpending - examine pending signals
4397 * @uset: where mask of pending signal is returned
4398 */
4399SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4400{
4401 sigset_t set;
4402
4403 if (sizeof(old_sigset_t) > sizeof(*uset))
4404 return -EINVAL;
4405
4406 do_sigpending(&set);
4407
4408 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4409 return -EFAULT;
4410
4411 return 0;
4412}
4413
4414#ifdef CONFIG_COMPAT
4415COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4416{
4417 sigset_t set;
4418
4419 do_sigpending(&set);
4420
4421 return put_user(set.sig[0], set32);
4422}
4423#endif
4424
4425#endif
4426
4427#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4428/**
4429 * sys_sigprocmask - examine and change blocked signals
4430 * @how: whether to add, remove, or set signals
4431 * @nset: signals to add or remove (if non-null)
4432 * @oset: previous value of signal mask if non-null
4433 *
4434 * Some platforms have their own version with special arguments;
4435 * others support only sys_rt_sigprocmask.
4436 */
4437
4438SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4439 old_sigset_t __user *, oset)
4440{
4441 old_sigset_t old_set, new_set;
4442 sigset_t new_blocked;
4443
4444 old_set = current->blocked.sig[0];
4445
4446 if (nset) {
4447 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4448 return -EFAULT;
4449
4450 new_blocked = current->blocked;
4451
4452 switch (how) {
4453 case SIG_BLOCK:
4454 sigaddsetmask(&new_blocked, new_set);
4455 break;
4456 case SIG_UNBLOCK:
4457 sigdelsetmask(&new_blocked, new_set);
4458 break;
4459 case SIG_SETMASK:
4460 new_blocked.sig[0] = new_set;
4461 break;
4462 default:
4463 return -EINVAL;
4464 }
4465
4466 set_current_blocked(&new_blocked);
4467 }
4468
4469 if (oset) {
4470 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4471 return -EFAULT;
4472 }
4473
4474 return 0;
4475}
4476#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4477
4478#ifndef CONFIG_ODD_RT_SIGACTION
4479/**
4480 * sys_rt_sigaction - alter an action taken by a process
4481 * @sig: signal to be sent
4482 * @act: new sigaction
4483 * @oact: used to save the previous sigaction
4484 * @sigsetsize: size of sigset_t type
4485 */
4486SYSCALL_DEFINE4(rt_sigaction, int, sig,
4487 const struct sigaction __user *, act,
4488 struct sigaction __user *, oact,
4489 size_t, sigsetsize)
4490{
4491 struct k_sigaction new_sa, old_sa;
4492 int ret;
4493
4494 /* XXX: Don't preclude handling different sized sigset_t's. */
4495 if (sigsetsize != sizeof(sigset_t))
4496 return -EINVAL;
4497
4498 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4499 return -EFAULT;
4500
4501 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4502 if (ret)
4503 return ret;
4504
4505 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4506 return -EFAULT;
4507
4508 return 0;
4509}
4510#ifdef CONFIG_COMPAT
4511COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4512 const struct compat_sigaction __user *, act,
4513 struct compat_sigaction __user *, oact,
4514 compat_size_t, sigsetsize)
4515{
4516 struct k_sigaction new_ka, old_ka;
4517#ifdef __ARCH_HAS_SA_RESTORER
4518 compat_uptr_t restorer;
4519#endif
4520 int ret;
4521
4522 /* XXX: Don't preclude handling different sized sigset_t's. */
4523 if (sigsetsize != sizeof(compat_sigset_t))
4524 return -EINVAL;
4525
4526 if (act) {
4527 compat_uptr_t handler;
4528 ret = get_user(handler, &act->sa_handler);
4529 new_ka.sa.sa_handler = compat_ptr(handler);
4530#ifdef __ARCH_HAS_SA_RESTORER
4531 ret |= get_user(restorer, &act->sa_restorer);
4532 new_ka.sa.sa_restorer = compat_ptr(restorer);
4533#endif
4534 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4535 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4536 if (ret)
4537 return -EFAULT;
4538 }
4539
4540 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4541 if (!ret && oact) {
4542 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4543 &oact->sa_handler);
4544 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4545 sizeof(oact->sa_mask));
4546 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4547#ifdef __ARCH_HAS_SA_RESTORER
4548 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4549 &oact->sa_restorer);
4550#endif
4551 }
4552 return ret;
4553}
4554#endif
4555#endif /* !CONFIG_ODD_RT_SIGACTION */
4556
4557#ifdef CONFIG_OLD_SIGACTION
4558SYSCALL_DEFINE3(sigaction, int, sig,
4559 const struct old_sigaction __user *, act,
4560 struct old_sigaction __user *, oact)
4561{
4562 struct k_sigaction new_ka, old_ka;
4563 int ret;
4564
4565 if (act) {
4566 old_sigset_t mask;
4567 if (!access_ok(act, sizeof(*act)) ||
4568 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4569 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4570 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4571 __get_user(mask, &act->sa_mask))
4572 return -EFAULT;
4573#ifdef __ARCH_HAS_KA_RESTORER
4574 new_ka.ka_restorer = NULL;
4575#endif
4576 siginitset(&new_ka.sa.sa_mask, mask);
4577 }
4578
4579 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4580
4581 if (!ret && oact) {
4582 if (!access_ok(oact, sizeof(*oact)) ||
4583 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4584 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4585 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4586 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4587 return -EFAULT;
4588 }
4589
4590 return ret;
4591}
4592#endif
4593#ifdef CONFIG_COMPAT_OLD_SIGACTION
4594COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4595 const struct compat_old_sigaction __user *, act,
4596 struct compat_old_sigaction __user *, oact)
4597{
4598 struct k_sigaction new_ka, old_ka;
4599 int ret;
4600 compat_old_sigset_t mask;
4601 compat_uptr_t handler, restorer;
4602
4603 if (act) {
4604 if (!access_ok(act, sizeof(*act)) ||
4605 __get_user(handler, &act->sa_handler) ||
4606 __get_user(restorer, &act->sa_restorer) ||
4607 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4608 __get_user(mask, &act->sa_mask))
4609 return -EFAULT;
4610
4611#ifdef __ARCH_HAS_KA_RESTORER
4612 new_ka.ka_restorer = NULL;
4613#endif
4614 new_ka.sa.sa_handler = compat_ptr(handler);
4615 new_ka.sa.sa_restorer = compat_ptr(restorer);
4616 siginitset(&new_ka.sa.sa_mask, mask);
4617 }
4618
4619 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4620
4621 if (!ret && oact) {
4622 if (!access_ok(oact, sizeof(*oact)) ||
4623 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4624 &oact->sa_handler) ||
4625 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4626 &oact->sa_restorer) ||
4627 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4628 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4629 return -EFAULT;
4630 }
4631 return ret;
4632}
4633#endif
4634
4635#ifdef CONFIG_SGETMASK_SYSCALL
4636
4637/*
4638 * For backwards compatibility. Functionality superseded by sigprocmask.
4639 */
4640SYSCALL_DEFINE0(sgetmask)
4641{
4642 /* SMP safe */
4643 return current->blocked.sig[0];
4644}
4645
4646SYSCALL_DEFINE1(ssetmask, int, newmask)
4647{
4648 int old = current->blocked.sig[0];
4649 sigset_t newset;
4650
4651 siginitset(&newset, newmask);
4652 set_current_blocked(&newset);
4653
4654 return old;
4655}
4656#endif /* CONFIG_SGETMASK_SYSCALL */
4657
4658#ifdef __ARCH_WANT_SYS_SIGNAL
4659/*
4660 * For backwards compatibility. Functionality superseded by sigaction.
4661 */
4662SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4663{
4664 struct k_sigaction new_sa, old_sa;
4665 int ret;
4666
4667 new_sa.sa.sa_handler = handler;
4668 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4669 sigemptyset(&new_sa.sa.sa_mask);
4670
4671 ret = do_sigaction(sig, &new_sa, &old_sa);
4672
4673 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4674}
4675#endif /* __ARCH_WANT_SYS_SIGNAL */
4676
4677#ifdef __ARCH_WANT_SYS_PAUSE
4678
4679SYSCALL_DEFINE0(pause)
4680{
4681 while (!signal_pending(current)) {
4682 __set_current_state(TASK_INTERRUPTIBLE);
4683 schedule();
4684 }
4685 return -ERESTARTNOHAND;
4686}
4687
4688#endif
4689
4690static int sigsuspend(sigset_t *set)
4691{
4692 current->saved_sigmask = current->blocked;
4693 set_current_blocked(set);
4694
4695 while (!signal_pending(current)) {
4696 __set_current_state(TASK_INTERRUPTIBLE);
4697 schedule();
4698 }
4699 set_restore_sigmask();
4700 return -ERESTARTNOHAND;
4701}
4702
4703/**
4704 * sys_rt_sigsuspend - replace the signal mask for a value with the
4705 * @unewset value until a signal is received
4706 * @unewset: new signal mask value
4707 * @sigsetsize: size of sigset_t type
4708 */
4709SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4710{
4711 sigset_t newset;
4712
4713 /* XXX: Don't preclude handling different sized sigset_t's. */
4714 if (sigsetsize != sizeof(sigset_t))
4715 return -EINVAL;
4716
4717 if (copy_from_user(&newset, unewset, sizeof(newset)))
4718 return -EFAULT;
4719 return sigsuspend(&newset);
4720}
4721
4722#ifdef CONFIG_COMPAT
4723COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4724{
4725 sigset_t newset;
4726
4727 /* XXX: Don't preclude handling different sized sigset_t's. */
4728 if (sigsetsize != sizeof(sigset_t))
4729 return -EINVAL;
4730
4731 if (get_compat_sigset(&newset, unewset))
4732 return -EFAULT;
4733 return sigsuspend(&newset);
4734}
4735#endif
4736
4737#ifdef CONFIG_OLD_SIGSUSPEND
4738SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4739{
4740 sigset_t blocked;
4741 siginitset(&blocked, mask);
4742 return sigsuspend(&blocked);
4743}
4744#endif
4745#ifdef CONFIG_OLD_SIGSUSPEND3
4746SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4747{
4748 sigset_t blocked;
4749 siginitset(&blocked, mask);
4750 return sigsuspend(&blocked);
4751}
4752#endif
4753
4754__weak const char *arch_vma_name(struct vm_area_struct *vma)
4755{
4756 return NULL;
4757}
4758
4759static inline void siginfo_buildtime_checks(void)
4760{
4761 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4762
4763 /* Verify the offsets in the two siginfos match */
4764#define CHECK_OFFSET(field) \
4765 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4766
4767 /* kill */
4768 CHECK_OFFSET(si_pid);
4769 CHECK_OFFSET(si_uid);
4770
4771 /* timer */
4772 CHECK_OFFSET(si_tid);
4773 CHECK_OFFSET(si_overrun);
4774 CHECK_OFFSET(si_value);
4775
4776 /* rt */
4777 CHECK_OFFSET(si_pid);
4778 CHECK_OFFSET(si_uid);
4779 CHECK_OFFSET(si_value);
4780
4781 /* sigchld */
4782 CHECK_OFFSET(si_pid);
4783 CHECK_OFFSET(si_uid);
4784 CHECK_OFFSET(si_status);
4785 CHECK_OFFSET(si_utime);
4786 CHECK_OFFSET(si_stime);
4787
4788 /* sigfault */
4789 CHECK_OFFSET(si_addr);
4790 CHECK_OFFSET(si_trapno);
4791 CHECK_OFFSET(si_addr_lsb);
4792 CHECK_OFFSET(si_lower);
4793 CHECK_OFFSET(si_upper);
4794 CHECK_OFFSET(si_pkey);
4795 CHECK_OFFSET(si_perf_data);
4796 CHECK_OFFSET(si_perf_type);
4797 CHECK_OFFSET(si_perf_flags);
4798
4799 /* sigpoll */
4800 CHECK_OFFSET(si_band);
4801 CHECK_OFFSET(si_fd);
4802
4803 /* sigsys */
4804 CHECK_OFFSET(si_call_addr);
4805 CHECK_OFFSET(si_syscall);
4806 CHECK_OFFSET(si_arch);
4807#undef CHECK_OFFSET
4808
4809 /* usb asyncio */
4810 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4811 offsetof(struct siginfo, si_addr));
4812 if (sizeof(int) == sizeof(void __user *)) {
4813 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4814 sizeof(void __user *));
4815 } else {
4816 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4817 sizeof_field(struct siginfo, si_uid)) !=
4818 sizeof(void __user *));
4819 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4820 offsetof(struct siginfo, si_uid));
4821 }
4822#ifdef CONFIG_COMPAT
4823 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4824 offsetof(struct compat_siginfo, si_addr));
4825 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4826 sizeof(compat_uptr_t));
4827 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4828 sizeof_field(struct siginfo, si_pid));
4829#endif
4830}
4831
4832#if defined(CONFIG_SYSCTL)
4833static struct ctl_table signal_debug_table[] = {
4834#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4835 {
4836 .procname = "exception-trace",
4837 .data = &show_unhandled_signals,
4838 .maxlen = sizeof(int),
4839 .mode = 0644,
4840 .proc_handler = proc_dointvec
4841 },
4842#endif
4843 { }
4844};
4845
4846static int __init init_signal_sysctls(void)
4847{
4848 register_sysctl_init("debug", signal_debug_table);
4849 return 0;
4850}
4851early_initcall(init_signal_sysctls);
4852#endif /* CONFIG_SYSCTL */
4853
4854void __init signals_init(void)
4855{
4856 siginfo_buildtime_checks();
4857
4858 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4859}
4860
4861#ifdef CONFIG_KGDB_KDB
4862#include <linux/kdb.h>
4863/*
4864 * kdb_send_sig - Allows kdb to send signals without exposing
4865 * signal internals. This function checks if the required locks are
4866 * available before calling the main signal code, to avoid kdb
4867 * deadlocks.
4868 */
4869void kdb_send_sig(struct task_struct *t, int sig)
4870{
4871 static struct task_struct *kdb_prev_t;
4872 int new_t, ret;
4873 if (!spin_trylock(&t->sighand->siglock)) {
4874 kdb_printf("Can't do kill command now.\n"
4875 "The sigmask lock is held somewhere else in "
4876 "kernel, try again later\n");
4877 return;
4878 }
4879 new_t = kdb_prev_t != t;
4880 kdb_prev_t = t;
4881 if (!task_is_running(t) && new_t) {
4882 spin_unlock(&t->sighand->siglock);
4883 kdb_printf("Process is not RUNNING, sending a signal from "
4884 "kdb risks deadlock\n"
4885 "on the run queue locks. "
4886 "The signal has _not_ been sent.\n"
4887 "Reissue the kill command if you want to risk "
4888 "the deadlock.\n");
4889 return;
4890 }
4891 ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4892 spin_unlock(&t->sighand->siglock);
4893 if (ret)
4894 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4895 sig, t->pid);
4896 else
4897 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4898}
4899#endif /* CONFIG_KGDB_KDB */