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