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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/coredump.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/ptrace.h>
24#include <linux/signal.h>
25#include <linux/signalfd.h>
26#include <linux/ratelimit.h>
27#include <linux/tracehook.h>
28#include <linux/capability.h>
29#include <linux/freezer.h>
30#include <linux/pid_namespace.h>
31#include <linux/nsproxy.h>
32#include <linux/user_namespace.h>
33#include <linux/uprobes.h>
34#include <linux/compat.h>
35#include <linux/cn_proc.h>
36#include <linux/compiler.h>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <linux/uaccess.h>
43#include <asm/unistd.h>
44#include <asm/siginfo.h>
45#include <asm/cacheflush.h>
46#include "audit.h" /* audit_signal_info() */
47
48/*
49 * SLAB caches for signal bits.
50 */
51
52static struct kmem_cache *sigqueue_cachep;
53
54int print_fatal_signals __read_mostly;
55
56static void __user *sig_handler(struct task_struct *t, int sig)
57{
58 return t->sighand->action[sig - 1].sa.sa_handler;
59}
60
61static int sig_handler_ignored(void __user *handler, int sig)
62{
63 /* Is it explicitly or implicitly ignored? */
64 return handler == SIG_IGN ||
65 (handler == SIG_DFL && sig_kernel_ignore(sig));
66}
67
68static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69{
70 void __user *handler;
71
72 handler = sig_handler(t, sig);
73
74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 handler == SIG_DFL && !force)
76 return 1;
77
78 return sig_handler_ignored(handler, sig);
79}
80
81static int sig_ignored(struct task_struct *t, int sig, bool force)
82{
83 /*
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
86 * unblocked.
87 */
88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 return 0;
90
91 if (!sig_task_ignored(t, sig, force))
92 return 0;
93
94 /*
95 * Tracers may want to know about even ignored signals.
96 */
97 return !t->ptrace;
98}
99
100/*
101 * Re-calculate pending state from the set of locally pending
102 * signals, globally pending signals, and blocked signals.
103 */
104static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105{
106 unsigned long ready;
107 long i;
108
109 switch (_NSIG_WORDS) {
110 default:
111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 ready |= signal->sig[i] &~ blocked->sig[i];
113 break;
114
115 case 4: ready = signal->sig[3] &~ blocked->sig[3];
116 ready |= signal->sig[2] &~ blocked->sig[2];
117 ready |= signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
119 break;
120
121 case 2: ready = signal->sig[1] &~ blocked->sig[1];
122 ready |= signal->sig[0] &~ blocked->sig[0];
123 break;
124
125 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 }
127 return ready != 0;
128}
129
130#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131
132static int recalc_sigpending_tsk(struct task_struct *t)
133{
134 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 PENDING(&t->pending, &t->blocked) ||
136 PENDING(&t->signal->shared_pending, &t->blocked)) {
137 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 return 1;
139 }
140 /*
141 * We must never clear the flag in another thread, or in current
142 * when it's possible the current syscall is returning -ERESTART*.
143 * So we don't clear it here, and only callers who know they should do.
144 */
145 return 0;
146}
147
148/*
149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150 * This is superfluous when called on current, the wakeup is a harmless no-op.
151 */
152void recalc_sigpending_and_wake(struct task_struct *t)
153{
154 if (recalc_sigpending_tsk(t))
155 signal_wake_up(t, 0);
156}
157
158void recalc_sigpending(void)
159{
160 if (!recalc_sigpending_tsk(current) && !freezing(current))
161 clear_thread_flag(TIF_SIGPENDING);
162
163}
164
165/* Given the mask, find the first available signal that should be serviced. */
166
167#define SYNCHRONOUS_MASK \
168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170
171int next_signal(struct sigpending *pending, sigset_t *mask)
172{
173 unsigned long i, *s, *m, x;
174 int sig = 0;
175
176 s = pending->signal.sig;
177 m = mask->sig;
178
179 /*
180 * Handle the first word specially: it contains the
181 * synchronous signals that need to be dequeued first.
182 */
183 x = *s &~ *m;
184 if (x) {
185 if (x & SYNCHRONOUS_MASK)
186 x &= SYNCHRONOUS_MASK;
187 sig = ffz(~x) + 1;
188 return sig;
189 }
190
191 switch (_NSIG_WORDS) {
192 default:
193 for (i = 1; i < _NSIG_WORDS; ++i) {
194 x = *++s &~ *++m;
195 if (!x)
196 continue;
197 sig = ffz(~x) + i*_NSIG_BPW + 1;
198 break;
199 }
200 break;
201
202 case 2:
203 x = s[1] &~ m[1];
204 if (!x)
205 break;
206 sig = ffz(~x) + _NSIG_BPW + 1;
207 break;
208
209 case 1:
210 /* Nothing to do */
211 break;
212 }
213
214 return sig;
215}
216
217static inline void print_dropped_signal(int sig)
218{
219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220
221 if (!print_fatal_signals)
222 return;
223
224 if (!__ratelimit(&ratelimit_state))
225 return;
226
227 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 current->comm, current->pid, sig);
229}
230
231/**
232 * task_set_jobctl_pending - set jobctl pending bits
233 * @task: target task
234 * @mask: pending bits to set
235 *
236 * Clear @mask from @task->jobctl. @mask must be subset of
237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
239 * cleared. If @task is already being killed or exiting, this function
240 * becomes noop.
241 *
242 * CONTEXT:
243 * Must be called with @task->sighand->siglock held.
244 *
245 * RETURNS:
246 * %true if @mask is set, %false if made noop because @task was dying.
247 */
248bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
249{
250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253
254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 return false;
256
257 if (mask & JOBCTL_STOP_SIGMASK)
258 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259
260 task->jobctl |= mask;
261 return true;
262}
263
264/**
265 * task_clear_jobctl_trapping - clear jobctl trapping bit
266 * @task: target task
267 *
268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269 * Clear it and wake up the ptracer. Note that we don't need any further
270 * locking. @task->siglock guarantees that @task->parent points to the
271 * ptracer.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 */
276void task_clear_jobctl_trapping(struct task_struct *task)
277{
278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 task->jobctl &= ~JOBCTL_TRAPPING;
280 smp_mb(); /* advised by wake_up_bit() */
281 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
282 }
283}
284
285/**
286 * task_clear_jobctl_pending - clear jobctl pending bits
287 * @task: target task
288 * @mask: pending bits to clear
289 *
290 * Clear @mask from @task->jobctl. @mask must be subset of
291 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
292 * STOP bits are cleared together.
293 *
294 * If clearing of @mask leaves no stop or trap pending, this function calls
295 * task_clear_jobctl_trapping().
296 *
297 * CONTEXT:
298 * Must be called with @task->sighand->siglock held.
299 */
300void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
301{
302 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
303
304 if (mask & JOBCTL_STOP_PENDING)
305 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
306
307 task->jobctl &= ~mask;
308
309 if (!(task->jobctl & JOBCTL_PENDING_MASK))
310 task_clear_jobctl_trapping(task);
311}
312
313/**
314 * task_participate_group_stop - participate in a group stop
315 * @task: task participating in a group stop
316 *
317 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
318 * Group stop states are cleared and the group stop count is consumed if
319 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
320 * stop, the appropriate %SIGNAL_* flags are set.
321 *
322 * CONTEXT:
323 * Must be called with @task->sighand->siglock held.
324 *
325 * RETURNS:
326 * %true if group stop completion should be notified to the parent, %false
327 * otherwise.
328 */
329static bool task_participate_group_stop(struct task_struct *task)
330{
331 struct signal_struct *sig = task->signal;
332 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
333
334 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
335
336 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
337
338 if (!consume)
339 return false;
340
341 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
342 sig->group_stop_count--;
343
344 /*
345 * Tell the caller to notify completion iff we are entering into a
346 * fresh group stop. Read comment in do_signal_stop() for details.
347 */
348 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
349 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
350 return true;
351 }
352 return false;
353}
354
355/*
356 * allocate a new signal queue record
357 * - this may be called without locks if and only if t == current, otherwise an
358 * appropriate lock must be held to stop the target task from exiting
359 */
360static struct sigqueue *
361__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
362{
363 struct sigqueue *q = NULL;
364 struct user_struct *user;
365
366 /*
367 * Protect access to @t credentials. This can go away when all
368 * callers hold rcu read lock.
369 */
370 rcu_read_lock();
371 user = get_uid(__task_cred(t)->user);
372 atomic_inc(&user->sigpending);
373 rcu_read_unlock();
374
375 if (override_rlimit ||
376 atomic_read(&user->sigpending) <=
377 task_rlimit(t, RLIMIT_SIGPENDING)) {
378 q = kmem_cache_alloc(sigqueue_cachep, flags);
379 } else {
380 print_dropped_signal(sig);
381 }
382
383 if (unlikely(q == NULL)) {
384 atomic_dec(&user->sigpending);
385 free_uid(user);
386 } else {
387 INIT_LIST_HEAD(&q->list);
388 q->flags = 0;
389 q->user = user;
390 }
391
392 return q;
393}
394
395static void __sigqueue_free(struct sigqueue *q)
396{
397 if (q->flags & SIGQUEUE_PREALLOC)
398 return;
399 atomic_dec(&q->user->sigpending);
400 free_uid(q->user);
401 kmem_cache_free(sigqueue_cachep, q);
402}
403
404void flush_sigqueue(struct sigpending *queue)
405{
406 struct sigqueue *q;
407
408 sigemptyset(&queue->signal);
409 while (!list_empty(&queue->list)) {
410 q = list_entry(queue->list.next, struct sigqueue , list);
411 list_del_init(&q->list);
412 __sigqueue_free(q);
413 }
414}
415
416/*
417 * Flush all pending signals for this kthread.
418 */
419void flush_signals(struct task_struct *t)
420{
421 unsigned long flags;
422
423 spin_lock_irqsave(&t->sighand->siglock, flags);
424 clear_tsk_thread_flag(t, TIF_SIGPENDING);
425 flush_sigqueue(&t->pending);
426 flush_sigqueue(&t->signal->shared_pending);
427 spin_unlock_irqrestore(&t->sighand->siglock, flags);
428}
429
430#ifdef CONFIG_POSIX_TIMERS
431static void __flush_itimer_signals(struct sigpending *pending)
432{
433 sigset_t signal, retain;
434 struct sigqueue *q, *n;
435
436 signal = pending->signal;
437 sigemptyset(&retain);
438
439 list_for_each_entry_safe(q, n, &pending->list, list) {
440 int sig = q->info.si_signo;
441
442 if (likely(q->info.si_code != SI_TIMER)) {
443 sigaddset(&retain, sig);
444 } else {
445 sigdelset(&signal, sig);
446 list_del_init(&q->list);
447 __sigqueue_free(q);
448 }
449 }
450
451 sigorsets(&pending->signal, &signal, &retain);
452}
453
454void flush_itimer_signals(void)
455{
456 struct task_struct *tsk = current;
457 unsigned long flags;
458
459 spin_lock_irqsave(&tsk->sighand->siglock, flags);
460 __flush_itimer_signals(&tsk->pending);
461 __flush_itimer_signals(&tsk->signal->shared_pending);
462 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
463}
464#endif
465
466void ignore_signals(struct task_struct *t)
467{
468 int i;
469
470 for (i = 0; i < _NSIG; ++i)
471 t->sighand->action[i].sa.sa_handler = SIG_IGN;
472
473 flush_signals(t);
474}
475
476/*
477 * Flush all handlers for a task.
478 */
479
480void
481flush_signal_handlers(struct task_struct *t, int force_default)
482{
483 int i;
484 struct k_sigaction *ka = &t->sighand->action[0];
485 for (i = _NSIG ; i != 0 ; i--) {
486 if (force_default || ka->sa.sa_handler != SIG_IGN)
487 ka->sa.sa_handler = SIG_DFL;
488 ka->sa.sa_flags = 0;
489#ifdef __ARCH_HAS_SA_RESTORER
490 ka->sa.sa_restorer = NULL;
491#endif
492 sigemptyset(&ka->sa.sa_mask);
493 ka++;
494 }
495}
496
497int unhandled_signal(struct task_struct *tsk, int sig)
498{
499 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
500 if (is_global_init(tsk))
501 return 1;
502 if (handler != SIG_IGN && handler != SIG_DFL)
503 return 0;
504 /* if ptraced, let the tracer determine */
505 return !tsk->ptrace;
506}
507
508static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
509{
510 struct sigqueue *q, *first = NULL;
511
512 /*
513 * Collect the siginfo appropriate to this signal. Check if
514 * there is another siginfo for the same signal.
515 */
516 list_for_each_entry(q, &list->list, list) {
517 if (q->info.si_signo == sig) {
518 if (first)
519 goto still_pending;
520 first = q;
521 }
522 }
523
524 sigdelset(&list->signal, sig);
525
526 if (first) {
527still_pending:
528 list_del_init(&first->list);
529 copy_siginfo(info, &first->info);
530 __sigqueue_free(first);
531 } else {
532 /*
533 * Ok, it wasn't in the queue. This must be
534 * a fast-pathed signal or we must have been
535 * out of queue space. So zero out the info.
536 */
537 info->si_signo = sig;
538 info->si_errno = 0;
539 info->si_code = SI_USER;
540 info->si_pid = 0;
541 info->si_uid = 0;
542 }
543}
544
545static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
546 siginfo_t *info)
547{
548 int sig = next_signal(pending, mask);
549
550 if (sig)
551 collect_signal(sig, pending, info);
552 return sig;
553}
554
555/*
556 * Dequeue a signal and return the element to the caller, which is
557 * expected to free it.
558 *
559 * All callers have to hold the siglock.
560 */
561int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
562{
563 int signr;
564
565 /* We only dequeue private signals from ourselves, we don't let
566 * signalfd steal them
567 */
568 signr = __dequeue_signal(&tsk->pending, mask, info);
569 if (!signr) {
570 signr = __dequeue_signal(&tsk->signal->shared_pending,
571 mask, info);
572#ifdef CONFIG_POSIX_TIMERS
573 /*
574 * itimer signal ?
575 *
576 * itimers are process shared and we restart periodic
577 * itimers in the signal delivery path to prevent DoS
578 * attacks in the high resolution timer case. This is
579 * compliant with the old way of self-restarting
580 * itimers, as the SIGALRM is a legacy signal and only
581 * queued once. Changing the restart behaviour to
582 * restart the timer in the signal dequeue path is
583 * reducing the timer noise on heavy loaded !highres
584 * systems too.
585 */
586 if (unlikely(signr == SIGALRM)) {
587 struct hrtimer *tmr = &tsk->signal->real_timer;
588
589 if (!hrtimer_is_queued(tmr) &&
590 tsk->signal->it_real_incr != 0) {
591 hrtimer_forward(tmr, tmr->base->get_time(),
592 tsk->signal->it_real_incr);
593 hrtimer_restart(tmr);
594 }
595 }
596#endif
597 }
598
599 recalc_sigpending();
600 if (!signr)
601 return 0;
602
603 if (unlikely(sig_kernel_stop(signr))) {
604 /*
605 * Set a marker that we have dequeued a stop signal. Our
606 * caller might release the siglock and then the pending
607 * stop signal it is about to process is no longer in the
608 * pending bitmasks, but must still be cleared by a SIGCONT
609 * (and overruled by a SIGKILL). So those cases clear this
610 * shared flag after we've set it. Note that this flag may
611 * remain set after the signal we return is ignored or
612 * handled. That doesn't matter because its only purpose
613 * is to alert stop-signal processing code when another
614 * processor has come along and cleared the flag.
615 */
616 current->jobctl |= JOBCTL_STOP_DEQUEUED;
617 }
618#ifdef CONFIG_POSIX_TIMERS
619 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
620 /*
621 * Release the siglock to ensure proper locking order
622 * of timer locks outside of siglocks. Note, we leave
623 * irqs disabled here, since the posix-timers code is
624 * about to disable them again anyway.
625 */
626 spin_unlock(&tsk->sighand->siglock);
627 do_schedule_next_timer(info);
628 spin_lock(&tsk->sighand->siglock);
629 }
630#endif
631 return signr;
632}
633
634/*
635 * Tell a process that it has a new active signal..
636 *
637 * NOTE! we rely on the previous spin_lock to
638 * lock interrupts for us! We can only be called with
639 * "siglock" held, and the local interrupt must
640 * have been disabled when that got acquired!
641 *
642 * No need to set need_resched since signal event passing
643 * goes through ->blocked
644 */
645void signal_wake_up_state(struct task_struct *t, unsigned int state)
646{
647 set_tsk_thread_flag(t, TIF_SIGPENDING);
648 /*
649 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
650 * case. We don't check t->state here because there is a race with it
651 * executing another processor and just now entering stopped state.
652 * By using wake_up_state, we ensure the process will wake up and
653 * handle its death signal.
654 */
655 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
656 kick_process(t);
657}
658
659/*
660 * Remove signals in mask from the pending set and queue.
661 * Returns 1 if any signals were found.
662 *
663 * All callers must be holding the siglock.
664 */
665static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
666{
667 struct sigqueue *q, *n;
668 sigset_t m;
669
670 sigandsets(&m, mask, &s->signal);
671 if (sigisemptyset(&m))
672 return 0;
673
674 sigandnsets(&s->signal, &s->signal, mask);
675 list_for_each_entry_safe(q, n, &s->list, list) {
676 if (sigismember(mask, q->info.si_signo)) {
677 list_del_init(&q->list);
678 __sigqueue_free(q);
679 }
680 }
681 return 1;
682}
683
684static inline int is_si_special(const struct siginfo *info)
685{
686 return info <= SEND_SIG_FORCED;
687}
688
689static inline bool si_fromuser(const struct siginfo *info)
690{
691 return info == SEND_SIG_NOINFO ||
692 (!is_si_special(info) && SI_FROMUSER(info));
693}
694
695/*
696 * called with RCU read lock from check_kill_permission()
697 */
698static int kill_ok_by_cred(struct task_struct *t)
699{
700 const struct cred *cred = current_cred();
701 const struct cred *tcred = __task_cred(t);
702
703 if (uid_eq(cred->euid, tcred->suid) ||
704 uid_eq(cred->euid, tcred->uid) ||
705 uid_eq(cred->uid, tcred->suid) ||
706 uid_eq(cred->uid, tcred->uid))
707 return 1;
708
709 if (ns_capable(tcred->user_ns, CAP_KILL))
710 return 1;
711
712 return 0;
713}
714
715/*
716 * Bad permissions for sending the signal
717 * - the caller must hold the RCU read lock
718 */
719static int check_kill_permission(int sig, struct siginfo *info,
720 struct task_struct *t)
721{
722 struct pid *sid;
723 int error;
724
725 if (!valid_signal(sig))
726 return -EINVAL;
727
728 if (!si_fromuser(info))
729 return 0;
730
731 error = audit_signal_info(sig, t); /* Let audit system see the signal */
732 if (error)
733 return error;
734
735 if (!same_thread_group(current, t) &&
736 !kill_ok_by_cred(t)) {
737 switch (sig) {
738 case SIGCONT:
739 sid = task_session(t);
740 /*
741 * We don't return the error if sid == NULL. The
742 * task was unhashed, the caller must notice this.
743 */
744 if (!sid || sid == task_session(current))
745 break;
746 default:
747 return -EPERM;
748 }
749 }
750
751 return security_task_kill(t, info, sig, 0);
752}
753
754/**
755 * ptrace_trap_notify - schedule trap to notify ptracer
756 * @t: tracee wanting to notify tracer
757 *
758 * This function schedules sticky ptrace trap which is cleared on the next
759 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
760 * ptracer.
761 *
762 * If @t is running, STOP trap will be taken. If trapped for STOP and
763 * ptracer is listening for events, tracee is woken up so that it can
764 * re-trap for the new event. If trapped otherwise, STOP trap will be
765 * eventually taken without returning to userland after the existing traps
766 * are finished by PTRACE_CONT.
767 *
768 * CONTEXT:
769 * Must be called with @task->sighand->siglock held.
770 */
771static void ptrace_trap_notify(struct task_struct *t)
772{
773 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
774 assert_spin_locked(&t->sighand->siglock);
775
776 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
777 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
778}
779
780/*
781 * Handle magic process-wide effects of stop/continue signals. Unlike
782 * the signal actions, these happen immediately at signal-generation
783 * time regardless of blocking, ignoring, or handling. This does the
784 * actual continuing for SIGCONT, but not the actual stopping for stop
785 * signals. The process stop is done as a signal action for SIG_DFL.
786 *
787 * Returns true if the signal should be actually delivered, otherwise
788 * it should be dropped.
789 */
790static bool prepare_signal(int sig, struct task_struct *p, bool force)
791{
792 struct signal_struct *signal = p->signal;
793 struct task_struct *t;
794 sigset_t flush;
795
796 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
797 if (!(signal->flags & SIGNAL_GROUP_EXIT))
798 return sig == SIGKILL;
799 /*
800 * The process is in the middle of dying, nothing to do.
801 */
802 } else if (sig_kernel_stop(sig)) {
803 /*
804 * This is a stop signal. Remove SIGCONT from all queues.
805 */
806 siginitset(&flush, sigmask(SIGCONT));
807 flush_sigqueue_mask(&flush, &signal->shared_pending);
808 for_each_thread(p, t)
809 flush_sigqueue_mask(&flush, &t->pending);
810 } else if (sig == SIGCONT) {
811 unsigned int why;
812 /*
813 * Remove all stop signals from all queues, wake all threads.
814 */
815 siginitset(&flush, SIG_KERNEL_STOP_MASK);
816 flush_sigqueue_mask(&flush, &signal->shared_pending);
817 for_each_thread(p, t) {
818 flush_sigqueue_mask(&flush, &t->pending);
819 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
820 if (likely(!(t->ptrace & PT_SEIZED)))
821 wake_up_state(t, __TASK_STOPPED);
822 else
823 ptrace_trap_notify(t);
824 }
825
826 /*
827 * Notify the parent with CLD_CONTINUED if we were stopped.
828 *
829 * If we were in the middle of a group stop, we pretend it
830 * was already finished, and then continued. Since SIGCHLD
831 * doesn't queue we report only CLD_STOPPED, as if the next
832 * CLD_CONTINUED was dropped.
833 */
834 why = 0;
835 if (signal->flags & SIGNAL_STOP_STOPPED)
836 why |= SIGNAL_CLD_CONTINUED;
837 else if (signal->group_stop_count)
838 why |= SIGNAL_CLD_STOPPED;
839
840 if (why) {
841 /*
842 * The first thread which returns from do_signal_stop()
843 * will take ->siglock, notice SIGNAL_CLD_MASK, and
844 * notify its parent. See get_signal_to_deliver().
845 */
846 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
847 signal->group_stop_count = 0;
848 signal->group_exit_code = 0;
849 }
850 }
851
852 return !sig_ignored(p, sig, force);
853}
854
855/*
856 * Test if P wants to take SIG. After we've checked all threads with this,
857 * it's equivalent to finding no threads not blocking SIG. Any threads not
858 * blocking SIG were ruled out because they are not running and already
859 * have pending signals. Such threads will dequeue from the shared queue
860 * as soon as they're available, so putting the signal on the shared queue
861 * will be equivalent to sending it to one such thread.
862 */
863static inline int wants_signal(int sig, struct task_struct *p)
864{
865 if (sigismember(&p->blocked, sig))
866 return 0;
867 if (p->flags & PF_EXITING)
868 return 0;
869 if (sig == SIGKILL)
870 return 1;
871 if (task_is_stopped_or_traced(p))
872 return 0;
873 return task_curr(p) || !signal_pending(p);
874}
875
876static void complete_signal(int sig, struct task_struct *p, int group)
877{
878 struct signal_struct *signal = p->signal;
879 struct task_struct *t;
880
881 /*
882 * Now find a thread we can wake up to take the signal off the queue.
883 *
884 * If the main thread wants the signal, it gets first crack.
885 * Probably the least surprising to the average bear.
886 */
887 if (wants_signal(sig, p))
888 t = p;
889 else if (!group || thread_group_empty(p))
890 /*
891 * There is just one thread and it does not need to be woken.
892 * It will dequeue unblocked signals before it runs again.
893 */
894 return;
895 else {
896 /*
897 * Otherwise try to find a suitable thread.
898 */
899 t = signal->curr_target;
900 while (!wants_signal(sig, t)) {
901 t = next_thread(t);
902 if (t == signal->curr_target)
903 /*
904 * No thread needs to be woken.
905 * Any eligible threads will see
906 * the signal in the queue soon.
907 */
908 return;
909 }
910 signal->curr_target = t;
911 }
912
913 /*
914 * Found a killable thread. If the signal will be fatal,
915 * then start taking the whole group down immediately.
916 */
917 if (sig_fatal(p, sig) &&
918 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
919 !sigismember(&t->real_blocked, sig) &&
920 (sig == SIGKILL || !t->ptrace)) {
921 /*
922 * This signal will be fatal to the whole group.
923 */
924 if (!sig_kernel_coredump(sig)) {
925 /*
926 * Start a group exit and wake everybody up.
927 * This way we don't have other threads
928 * running and doing things after a slower
929 * thread has the fatal signal pending.
930 */
931 signal->flags = SIGNAL_GROUP_EXIT;
932 signal->group_exit_code = sig;
933 signal->group_stop_count = 0;
934 t = p;
935 do {
936 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
937 sigaddset(&t->pending.signal, SIGKILL);
938 signal_wake_up(t, 1);
939 } while_each_thread(p, t);
940 return;
941 }
942 }
943
944 /*
945 * The signal is already in the shared-pending queue.
946 * Tell the chosen thread to wake up and dequeue it.
947 */
948 signal_wake_up(t, sig == SIGKILL);
949 return;
950}
951
952static inline int legacy_queue(struct sigpending *signals, int sig)
953{
954 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
955}
956
957#ifdef CONFIG_USER_NS
958static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
959{
960 if (current_user_ns() == task_cred_xxx(t, user_ns))
961 return;
962
963 if (SI_FROMKERNEL(info))
964 return;
965
966 rcu_read_lock();
967 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
968 make_kuid(current_user_ns(), info->si_uid));
969 rcu_read_unlock();
970}
971#else
972static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
973{
974 return;
975}
976#endif
977
978static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
979 int group, int from_ancestor_ns)
980{
981 struct sigpending *pending;
982 struct sigqueue *q;
983 int override_rlimit;
984 int ret = 0, result;
985
986 assert_spin_locked(&t->sighand->siglock);
987
988 result = TRACE_SIGNAL_IGNORED;
989 if (!prepare_signal(sig, t,
990 from_ancestor_ns || (info == SEND_SIG_FORCED)))
991 goto ret;
992
993 pending = group ? &t->signal->shared_pending : &t->pending;
994 /*
995 * Short-circuit ignored signals and support queuing
996 * exactly one non-rt signal, so that we can get more
997 * detailed information about the cause of the signal.
998 */
999 result = TRACE_SIGNAL_ALREADY_PENDING;
1000 if (legacy_queue(pending, sig))
1001 goto ret;
1002
1003 result = TRACE_SIGNAL_DELIVERED;
1004 /*
1005 * fast-pathed signals for kernel-internal things like SIGSTOP
1006 * or SIGKILL.
1007 */
1008 if (info == SEND_SIG_FORCED)
1009 goto out_set;
1010
1011 /*
1012 * Real-time signals must be queued if sent by sigqueue, or
1013 * some other real-time mechanism. It is implementation
1014 * defined whether kill() does so. We attempt to do so, on
1015 * the principle of least surprise, but since kill is not
1016 * allowed to fail with EAGAIN when low on memory we just
1017 * make sure at least one signal gets delivered and don't
1018 * pass on the info struct.
1019 */
1020 if (sig < SIGRTMIN)
1021 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1022 else
1023 override_rlimit = 0;
1024
1025 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1026 override_rlimit);
1027 if (q) {
1028 list_add_tail(&q->list, &pending->list);
1029 switch ((unsigned long) info) {
1030 case (unsigned long) SEND_SIG_NOINFO:
1031 q->info.si_signo = sig;
1032 q->info.si_errno = 0;
1033 q->info.si_code = SI_USER;
1034 q->info.si_pid = task_tgid_nr_ns(current,
1035 task_active_pid_ns(t));
1036 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1037 break;
1038 case (unsigned long) SEND_SIG_PRIV:
1039 q->info.si_signo = sig;
1040 q->info.si_errno = 0;
1041 q->info.si_code = SI_KERNEL;
1042 q->info.si_pid = 0;
1043 q->info.si_uid = 0;
1044 break;
1045 default:
1046 copy_siginfo(&q->info, info);
1047 if (from_ancestor_ns)
1048 q->info.si_pid = 0;
1049 break;
1050 }
1051
1052 userns_fixup_signal_uid(&q->info, t);
1053
1054 } else if (!is_si_special(info)) {
1055 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1056 /*
1057 * Queue overflow, abort. We may abort if the
1058 * signal was rt and sent by user using something
1059 * other than kill().
1060 */
1061 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1062 ret = -EAGAIN;
1063 goto ret;
1064 } else {
1065 /*
1066 * This is a silent loss of information. We still
1067 * send the signal, but the *info bits are lost.
1068 */
1069 result = TRACE_SIGNAL_LOSE_INFO;
1070 }
1071 }
1072
1073out_set:
1074 signalfd_notify(t, sig);
1075 sigaddset(&pending->signal, sig);
1076 complete_signal(sig, t, group);
1077ret:
1078 trace_signal_generate(sig, info, t, group, result);
1079 return ret;
1080}
1081
1082static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1083 int group)
1084{
1085 int from_ancestor_ns = 0;
1086
1087#ifdef CONFIG_PID_NS
1088 from_ancestor_ns = si_fromuser(info) &&
1089 !task_pid_nr_ns(current, task_active_pid_ns(t));
1090#endif
1091
1092 return __send_signal(sig, info, t, group, from_ancestor_ns);
1093}
1094
1095static void print_fatal_signal(int signr)
1096{
1097 struct pt_regs *regs = signal_pt_regs();
1098 pr_info("potentially unexpected fatal signal %d.\n", signr);
1099
1100#if defined(__i386__) && !defined(__arch_um__)
1101 pr_info("code at %08lx: ", regs->ip);
1102 {
1103 int i;
1104 for (i = 0; i < 16; i++) {
1105 unsigned char insn;
1106
1107 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1108 break;
1109 pr_cont("%02x ", insn);
1110 }
1111 }
1112 pr_cont("\n");
1113#endif
1114 preempt_disable();
1115 show_regs(regs);
1116 preempt_enable();
1117}
1118
1119static int __init setup_print_fatal_signals(char *str)
1120{
1121 get_option (&str, &print_fatal_signals);
1122
1123 return 1;
1124}
1125
1126__setup("print-fatal-signals=", setup_print_fatal_signals);
1127
1128int
1129__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1130{
1131 return send_signal(sig, info, p, 1);
1132}
1133
1134static int
1135specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1136{
1137 return send_signal(sig, info, t, 0);
1138}
1139
1140int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1141 bool group)
1142{
1143 unsigned long flags;
1144 int ret = -ESRCH;
1145
1146 if (lock_task_sighand(p, &flags)) {
1147 ret = send_signal(sig, info, p, group);
1148 unlock_task_sighand(p, &flags);
1149 }
1150
1151 return ret;
1152}
1153
1154/*
1155 * Force a signal that the process can't ignore: if necessary
1156 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1157 *
1158 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1159 * since we do not want to have a signal handler that was blocked
1160 * be invoked when user space had explicitly blocked it.
1161 *
1162 * We don't want to have recursive SIGSEGV's etc, for example,
1163 * that is why we also clear SIGNAL_UNKILLABLE.
1164 */
1165int
1166force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1167{
1168 unsigned long int flags;
1169 int ret, blocked, ignored;
1170 struct k_sigaction *action;
1171
1172 spin_lock_irqsave(&t->sighand->siglock, flags);
1173 action = &t->sighand->action[sig-1];
1174 ignored = action->sa.sa_handler == SIG_IGN;
1175 blocked = sigismember(&t->blocked, sig);
1176 if (blocked || ignored) {
1177 action->sa.sa_handler = SIG_DFL;
1178 if (blocked) {
1179 sigdelset(&t->blocked, sig);
1180 recalc_sigpending_and_wake(t);
1181 }
1182 }
1183 if (action->sa.sa_handler == SIG_DFL)
1184 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1185 ret = specific_send_sig_info(sig, info, t);
1186 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1187
1188 return ret;
1189}
1190
1191/*
1192 * Nuke all other threads in the group.
1193 */
1194int zap_other_threads(struct task_struct *p)
1195{
1196 struct task_struct *t = p;
1197 int count = 0;
1198
1199 p->signal->group_stop_count = 0;
1200
1201 while_each_thread(p, t) {
1202 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1203 count++;
1204
1205 /* Don't bother with already dead threads */
1206 if (t->exit_state)
1207 continue;
1208 sigaddset(&t->pending.signal, SIGKILL);
1209 signal_wake_up(t, 1);
1210 }
1211
1212 return count;
1213}
1214
1215struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1216 unsigned long *flags)
1217{
1218 struct sighand_struct *sighand;
1219
1220 for (;;) {
1221 /*
1222 * Disable interrupts early to avoid deadlocks.
1223 * See rcu_read_unlock() comment header for details.
1224 */
1225 local_irq_save(*flags);
1226 rcu_read_lock();
1227 sighand = rcu_dereference(tsk->sighand);
1228 if (unlikely(sighand == NULL)) {
1229 rcu_read_unlock();
1230 local_irq_restore(*flags);
1231 break;
1232 }
1233 /*
1234 * This sighand can be already freed and even reused, but
1235 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1236 * initializes ->siglock: this slab can't go away, it has
1237 * the same object type, ->siglock can't be reinitialized.
1238 *
1239 * We need to ensure that tsk->sighand is still the same
1240 * after we take the lock, we can race with de_thread() or
1241 * __exit_signal(). In the latter case the next iteration
1242 * must see ->sighand == NULL.
1243 */
1244 spin_lock(&sighand->siglock);
1245 if (likely(sighand == tsk->sighand)) {
1246 rcu_read_unlock();
1247 break;
1248 }
1249 spin_unlock(&sighand->siglock);
1250 rcu_read_unlock();
1251 local_irq_restore(*flags);
1252 }
1253
1254 return sighand;
1255}
1256
1257/*
1258 * send signal info to all the members of a group
1259 */
1260int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1261{
1262 int ret;
1263
1264 rcu_read_lock();
1265 ret = check_kill_permission(sig, info, p);
1266 rcu_read_unlock();
1267
1268 if (!ret && sig)
1269 ret = do_send_sig_info(sig, info, p, true);
1270
1271 return ret;
1272}
1273
1274/*
1275 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1276 * control characters do (^C, ^Z etc)
1277 * - the caller must hold at least a readlock on tasklist_lock
1278 */
1279int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1280{
1281 struct task_struct *p = NULL;
1282 int retval, success;
1283
1284 success = 0;
1285 retval = -ESRCH;
1286 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1287 int err = group_send_sig_info(sig, info, p);
1288 success |= !err;
1289 retval = err;
1290 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1291 return success ? 0 : retval;
1292}
1293
1294int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1295{
1296 int error = -ESRCH;
1297 struct task_struct *p;
1298
1299 for (;;) {
1300 rcu_read_lock();
1301 p = pid_task(pid, PIDTYPE_PID);
1302 if (p)
1303 error = group_send_sig_info(sig, info, p);
1304 rcu_read_unlock();
1305 if (likely(!p || error != -ESRCH))
1306 return error;
1307
1308 /*
1309 * The task was unhashed in between, try again. If it
1310 * is dead, pid_task() will return NULL, if we race with
1311 * de_thread() it will find the new leader.
1312 */
1313 }
1314}
1315
1316int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1317{
1318 int error;
1319 rcu_read_lock();
1320 error = kill_pid_info(sig, info, find_vpid(pid));
1321 rcu_read_unlock();
1322 return error;
1323}
1324
1325static int kill_as_cred_perm(const struct cred *cred,
1326 struct task_struct *target)
1327{
1328 const struct cred *pcred = __task_cred(target);
1329 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1330 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1331 return 0;
1332 return 1;
1333}
1334
1335/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1336int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1337 const struct cred *cred, u32 secid)
1338{
1339 int ret = -EINVAL;
1340 struct task_struct *p;
1341 unsigned long flags;
1342
1343 if (!valid_signal(sig))
1344 return ret;
1345
1346 rcu_read_lock();
1347 p = pid_task(pid, PIDTYPE_PID);
1348 if (!p) {
1349 ret = -ESRCH;
1350 goto out_unlock;
1351 }
1352 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1353 ret = -EPERM;
1354 goto out_unlock;
1355 }
1356 ret = security_task_kill(p, info, sig, secid);
1357 if (ret)
1358 goto out_unlock;
1359
1360 if (sig) {
1361 if (lock_task_sighand(p, &flags)) {
1362 ret = __send_signal(sig, info, p, 1, 0);
1363 unlock_task_sighand(p, &flags);
1364 } else
1365 ret = -ESRCH;
1366 }
1367out_unlock:
1368 rcu_read_unlock();
1369 return ret;
1370}
1371EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1372
1373/*
1374 * kill_something_info() interprets pid in interesting ways just like kill(2).
1375 *
1376 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1377 * is probably wrong. Should make it like BSD or SYSV.
1378 */
1379
1380static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1381{
1382 int ret;
1383
1384 if (pid > 0) {
1385 rcu_read_lock();
1386 ret = kill_pid_info(sig, info, find_vpid(pid));
1387 rcu_read_unlock();
1388 return ret;
1389 }
1390
1391 read_lock(&tasklist_lock);
1392 if (pid != -1) {
1393 ret = __kill_pgrp_info(sig, info,
1394 pid ? find_vpid(-pid) : task_pgrp(current));
1395 } else {
1396 int retval = 0, count = 0;
1397 struct task_struct * p;
1398
1399 for_each_process(p) {
1400 if (task_pid_vnr(p) > 1 &&
1401 !same_thread_group(p, current)) {
1402 int err = group_send_sig_info(sig, info, p);
1403 ++count;
1404 if (err != -EPERM)
1405 retval = err;
1406 }
1407 }
1408 ret = count ? retval : -ESRCH;
1409 }
1410 read_unlock(&tasklist_lock);
1411
1412 return ret;
1413}
1414
1415/*
1416 * These are for backward compatibility with the rest of the kernel source.
1417 */
1418
1419int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1420{
1421 /*
1422 * Make sure legacy kernel users don't send in bad values
1423 * (normal paths check this in check_kill_permission).
1424 */
1425 if (!valid_signal(sig))
1426 return -EINVAL;
1427
1428 return do_send_sig_info(sig, info, p, false);
1429}
1430
1431#define __si_special(priv) \
1432 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1433
1434int
1435send_sig(int sig, struct task_struct *p, int priv)
1436{
1437 return send_sig_info(sig, __si_special(priv), p);
1438}
1439
1440void
1441force_sig(int sig, struct task_struct *p)
1442{
1443 force_sig_info(sig, SEND_SIG_PRIV, p);
1444}
1445
1446/*
1447 * When things go south during signal handling, we
1448 * will force a SIGSEGV. And if the signal that caused
1449 * the problem was already a SIGSEGV, we'll want to
1450 * make sure we don't even try to deliver the signal..
1451 */
1452int
1453force_sigsegv(int sig, struct task_struct *p)
1454{
1455 if (sig == SIGSEGV) {
1456 unsigned long flags;
1457 spin_lock_irqsave(&p->sighand->siglock, flags);
1458 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1459 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1460 }
1461 force_sig(SIGSEGV, p);
1462 return 0;
1463}
1464
1465int kill_pgrp(struct pid *pid, int sig, int priv)
1466{
1467 int ret;
1468
1469 read_lock(&tasklist_lock);
1470 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1471 read_unlock(&tasklist_lock);
1472
1473 return ret;
1474}
1475EXPORT_SYMBOL(kill_pgrp);
1476
1477int kill_pid(struct pid *pid, int sig, int priv)
1478{
1479 return kill_pid_info(sig, __si_special(priv), pid);
1480}
1481EXPORT_SYMBOL(kill_pid);
1482
1483/*
1484 * These functions support sending signals using preallocated sigqueue
1485 * structures. This is needed "because realtime applications cannot
1486 * afford to lose notifications of asynchronous events, like timer
1487 * expirations or I/O completions". In the case of POSIX Timers
1488 * we allocate the sigqueue structure from the timer_create. If this
1489 * allocation fails we are able to report the failure to the application
1490 * with an EAGAIN error.
1491 */
1492struct sigqueue *sigqueue_alloc(void)
1493{
1494 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1495
1496 if (q)
1497 q->flags |= SIGQUEUE_PREALLOC;
1498
1499 return q;
1500}
1501
1502void sigqueue_free(struct sigqueue *q)
1503{
1504 unsigned long flags;
1505 spinlock_t *lock = ¤t->sighand->siglock;
1506
1507 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1508 /*
1509 * We must hold ->siglock while testing q->list
1510 * to serialize with collect_signal() or with
1511 * __exit_signal()->flush_sigqueue().
1512 */
1513 spin_lock_irqsave(lock, flags);
1514 q->flags &= ~SIGQUEUE_PREALLOC;
1515 /*
1516 * If it is queued it will be freed when dequeued,
1517 * like the "regular" sigqueue.
1518 */
1519 if (!list_empty(&q->list))
1520 q = NULL;
1521 spin_unlock_irqrestore(lock, flags);
1522
1523 if (q)
1524 __sigqueue_free(q);
1525}
1526
1527int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1528{
1529 int sig = q->info.si_signo;
1530 struct sigpending *pending;
1531 unsigned long flags;
1532 int ret, result;
1533
1534 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1535
1536 ret = -1;
1537 if (!likely(lock_task_sighand(t, &flags)))
1538 goto ret;
1539
1540 ret = 1; /* the signal is ignored */
1541 result = TRACE_SIGNAL_IGNORED;
1542 if (!prepare_signal(sig, t, false))
1543 goto out;
1544
1545 ret = 0;
1546 if (unlikely(!list_empty(&q->list))) {
1547 /*
1548 * If an SI_TIMER entry is already queue just increment
1549 * the overrun count.
1550 */
1551 BUG_ON(q->info.si_code != SI_TIMER);
1552 q->info.si_overrun++;
1553 result = TRACE_SIGNAL_ALREADY_PENDING;
1554 goto out;
1555 }
1556 q->info.si_overrun = 0;
1557
1558 signalfd_notify(t, sig);
1559 pending = group ? &t->signal->shared_pending : &t->pending;
1560 list_add_tail(&q->list, &pending->list);
1561 sigaddset(&pending->signal, sig);
1562 complete_signal(sig, t, group);
1563 result = TRACE_SIGNAL_DELIVERED;
1564out:
1565 trace_signal_generate(sig, &q->info, t, group, result);
1566 unlock_task_sighand(t, &flags);
1567ret:
1568 return ret;
1569}
1570
1571/*
1572 * Let a parent know about the death of a child.
1573 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1574 *
1575 * Returns true if our parent ignored us and so we've switched to
1576 * self-reaping.
1577 */
1578bool do_notify_parent(struct task_struct *tsk, int sig)
1579{
1580 struct siginfo info;
1581 unsigned long flags;
1582 struct sighand_struct *psig;
1583 bool autoreap = false;
1584 cputime_t utime, stime;
1585
1586 BUG_ON(sig == -1);
1587
1588 /* do_notify_parent_cldstop should have been called instead. */
1589 BUG_ON(task_is_stopped_or_traced(tsk));
1590
1591 BUG_ON(!tsk->ptrace &&
1592 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1593
1594 if (sig != SIGCHLD) {
1595 /*
1596 * This is only possible if parent == real_parent.
1597 * Check if it has changed security domain.
1598 */
1599 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1600 sig = SIGCHLD;
1601 }
1602
1603 info.si_signo = sig;
1604 info.si_errno = 0;
1605 /*
1606 * We are under tasklist_lock here so our parent is tied to
1607 * us and cannot change.
1608 *
1609 * task_active_pid_ns will always return the same pid namespace
1610 * until a task passes through release_task.
1611 *
1612 * write_lock() currently calls preempt_disable() which is the
1613 * same as rcu_read_lock(), but according to Oleg, this is not
1614 * correct to rely on this
1615 */
1616 rcu_read_lock();
1617 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1618 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1619 task_uid(tsk));
1620 rcu_read_unlock();
1621
1622 task_cputime(tsk, &utime, &stime);
1623 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1624 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1625
1626 info.si_status = tsk->exit_code & 0x7f;
1627 if (tsk->exit_code & 0x80)
1628 info.si_code = CLD_DUMPED;
1629 else if (tsk->exit_code & 0x7f)
1630 info.si_code = CLD_KILLED;
1631 else {
1632 info.si_code = CLD_EXITED;
1633 info.si_status = tsk->exit_code >> 8;
1634 }
1635
1636 psig = tsk->parent->sighand;
1637 spin_lock_irqsave(&psig->siglock, flags);
1638 if (!tsk->ptrace && sig == SIGCHLD &&
1639 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1640 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1641 /*
1642 * We are exiting and our parent doesn't care. POSIX.1
1643 * defines special semantics for setting SIGCHLD to SIG_IGN
1644 * or setting the SA_NOCLDWAIT flag: we should be reaped
1645 * automatically and not left for our parent's wait4 call.
1646 * Rather than having the parent do it as a magic kind of
1647 * signal handler, we just set this to tell do_exit that we
1648 * can be cleaned up without becoming a zombie. Note that
1649 * we still call __wake_up_parent in this case, because a
1650 * blocked sys_wait4 might now return -ECHILD.
1651 *
1652 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1653 * is implementation-defined: we do (if you don't want
1654 * it, just use SIG_IGN instead).
1655 */
1656 autoreap = true;
1657 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1658 sig = 0;
1659 }
1660 if (valid_signal(sig) && sig)
1661 __group_send_sig_info(sig, &info, tsk->parent);
1662 __wake_up_parent(tsk, tsk->parent);
1663 spin_unlock_irqrestore(&psig->siglock, flags);
1664
1665 return autoreap;
1666}
1667
1668/**
1669 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1670 * @tsk: task reporting the state change
1671 * @for_ptracer: the notification is for ptracer
1672 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1673 *
1674 * Notify @tsk's parent that the stopped/continued state has changed. If
1675 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1676 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1677 *
1678 * CONTEXT:
1679 * Must be called with tasklist_lock at least read locked.
1680 */
1681static void do_notify_parent_cldstop(struct task_struct *tsk,
1682 bool for_ptracer, int why)
1683{
1684 struct siginfo info;
1685 unsigned long flags;
1686 struct task_struct *parent;
1687 struct sighand_struct *sighand;
1688 cputime_t utime, stime;
1689
1690 if (for_ptracer) {
1691 parent = tsk->parent;
1692 } else {
1693 tsk = tsk->group_leader;
1694 parent = tsk->real_parent;
1695 }
1696
1697 info.si_signo = SIGCHLD;
1698 info.si_errno = 0;
1699 /*
1700 * see comment in do_notify_parent() about the following 4 lines
1701 */
1702 rcu_read_lock();
1703 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1704 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1705 rcu_read_unlock();
1706
1707 task_cputime(tsk, &utime, &stime);
1708 info.si_utime = cputime_to_clock_t(utime);
1709 info.si_stime = cputime_to_clock_t(stime);
1710
1711 info.si_code = why;
1712 switch (why) {
1713 case CLD_CONTINUED:
1714 info.si_status = SIGCONT;
1715 break;
1716 case CLD_STOPPED:
1717 info.si_status = tsk->signal->group_exit_code & 0x7f;
1718 break;
1719 case CLD_TRAPPED:
1720 info.si_status = tsk->exit_code & 0x7f;
1721 break;
1722 default:
1723 BUG();
1724 }
1725
1726 sighand = parent->sighand;
1727 spin_lock_irqsave(&sighand->siglock, flags);
1728 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1729 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1730 __group_send_sig_info(SIGCHLD, &info, parent);
1731 /*
1732 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1733 */
1734 __wake_up_parent(tsk, parent);
1735 spin_unlock_irqrestore(&sighand->siglock, flags);
1736}
1737
1738static inline int may_ptrace_stop(void)
1739{
1740 if (!likely(current->ptrace))
1741 return 0;
1742 /*
1743 * Are we in the middle of do_coredump?
1744 * If so and our tracer is also part of the coredump stopping
1745 * is a deadlock situation, and pointless because our tracer
1746 * is dead so don't allow us to stop.
1747 * If SIGKILL was already sent before the caller unlocked
1748 * ->siglock we must see ->core_state != NULL. Otherwise it
1749 * is safe to enter schedule().
1750 *
1751 * This is almost outdated, a task with the pending SIGKILL can't
1752 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1753 * after SIGKILL was already dequeued.
1754 */
1755 if (unlikely(current->mm->core_state) &&
1756 unlikely(current->mm == current->parent->mm))
1757 return 0;
1758
1759 return 1;
1760}
1761
1762/*
1763 * Return non-zero if there is a SIGKILL that should be waking us up.
1764 * Called with the siglock held.
1765 */
1766static int sigkill_pending(struct task_struct *tsk)
1767{
1768 return sigismember(&tsk->pending.signal, SIGKILL) ||
1769 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1770}
1771
1772/*
1773 * This must be called with current->sighand->siglock held.
1774 *
1775 * This should be the path for all ptrace stops.
1776 * We always set current->last_siginfo while stopped here.
1777 * That makes it a way to test a stopped process for
1778 * being ptrace-stopped vs being job-control-stopped.
1779 *
1780 * If we actually decide not to stop at all because the tracer
1781 * is gone, we keep current->exit_code unless clear_code.
1782 */
1783static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1784 __releases(¤t->sighand->siglock)
1785 __acquires(¤t->sighand->siglock)
1786{
1787 bool gstop_done = false;
1788
1789 if (arch_ptrace_stop_needed(exit_code, info)) {
1790 /*
1791 * The arch code has something special to do before a
1792 * ptrace stop. This is allowed to block, e.g. for faults
1793 * on user stack pages. We can't keep the siglock while
1794 * calling arch_ptrace_stop, so we must release it now.
1795 * To preserve proper semantics, we must do this before
1796 * any signal bookkeeping like checking group_stop_count.
1797 * Meanwhile, a SIGKILL could come in before we retake the
1798 * siglock. That must prevent us from sleeping in TASK_TRACED.
1799 * So after regaining the lock, we must check for SIGKILL.
1800 */
1801 spin_unlock_irq(¤t->sighand->siglock);
1802 arch_ptrace_stop(exit_code, info);
1803 spin_lock_irq(¤t->sighand->siglock);
1804 if (sigkill_pending(current))
1805 return;
1806 }
1807
1808 /*
1809 * We're committing to trapping. TRACED should be visible before
1810 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1811 * Also, transition to TRACED and updates to ->jobctl should be
1812 * atomic with respect to siglock and should be done after the arch
1813 * hook as siglock is released and regrabbed across it.
1814 */
1815 set_current_state(TASK_TRACED);
1816
1817 current->last_siginfo = info;
1818 current->exit_code = exit_code;
1819
1820 /*
1821 * If @why is CLD_STOPPED, we're trapping to participate in a group
1822 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1823 * across siglock relocks since INTERRUPT was scheduled, PENDING
1824 * could be clear now. We act as if SIGCONT is received after
1825 * TASK_TRACED is entered - ignore it.
1826 */
1827 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1828 gstop_done = task_participate_group_stop(current);
1829
1830 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1831 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1832 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1833 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1834
1835 /* entering a trap, clear TRAPPING */
1836 task_clear_jobctl_trapping(current);
1837
1838 spin_unlock_irq(¤t->sighand->siglock);
1839 read_lock(&tasklist_lock);
1840 if (may_ptrace_stop()) {
1841 /*
1842 * Notify parents of the stop.
1843 *
1844 * While ptraced, there are two parents - the ptracer and
1845 * the real_parent of the group_leader. The ptracer should
1846 * know about every stop while the real parent is only
1847 * interested in the completion of group stop. The states
1848 * for the two don't interact with each other. Notify
1849 * separately unless they're gonna be duplicates.
1850 */
1851 do_notify_parent_cldstop(current, true, why);
1852 if (gstop_done && ptrace_reparented(current))
1853 do_notify_parent_cldstop(current, false, why);
1854
1855 /*
1856 * Don't want to allow preemption here, because
1857 * sys_ptrace() needs this task to be inactive.
1858 *
1859 * XXX: implement read_unlock_no_resched().
1860 */
1861 preempt_disable();
1862 read_unlock(&tasklist_lock);
1863 preempt_enable_no_resched();
1864 freezable_schedule();
1865 } else {
1866 /*
1867 * By the time we got the lock, our tracer went away.
1868 * Don't drop the lock yet, another tracer may come.
1869 *
1870 * If @gstop_done, the ptracer went away between group stop
1871 * completion and here. During detach, it would have set
1872 * JOBCTL_STOP_PENDING on us and we'll re-enter
1873 * TASK_STOPPED in do_signal_stop() on return, so notifying
1874 * the real parent of the group stop completion is enough.
1875 */
1876 if (gstop_done)
1877 do_notify_parent_cldstop(current, false, why);
1878
1879 /* tasklist protects us from ptrace_freeze_traced() */
1880 __set_current_state(TASK_RUNNING);
1881 if (clear_code)
1882 current->exit_code = 0;
1883 read_unlock(&tasklist_lock);
1884 }
1885
1886 /*
1887 * We are back. Now reacquire the siglock before touching
1888 * last_siginfo, so that we are sure to have synchronized with
1889 * any signal-sending on another CPU that wants to examine it.
1890 */
1891 spin_lock_irq(¤t->sighand->siglock);
1892 current->last_siginfo = NULL;
1893
1894 /* LISTENING can be set only during STOP traps, clear it */
1895 current->jobctl &= ~JOBCTL_LISTENING;
1896
1897 /*
1898 * Queued signals ignored us while we were stopped for tracing.
1899 * So check for any that we should take before resuming user mode.
1900 * This sets TIF_SIGPENDING, but never clears it.
1901 */
1902 recalc_sigpending_tsk(current);
1903}
1904
1905static void ptrace_do_notify(int signr, int exit_code, int why)
1906{
1907 siginfo_t info;
1908
1909 memset(&info, 0, sizeof info);
1910 info.si_signo = signr;
1911 info.si_code = exit_code;
1912 info.si_pid = task_pid_vnr(current);
1913 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1914
1915 /* Let the debugger run. */
1916 ptrace_stop(exit_code, why, 1, &info);
1917}
1918
1919void ptrace_notify(int exit_code)
1920{
1921 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1922 if (unlikely(current->task_works))
1923 task_work_run();
1924
1925 spin_lock_irq(¤t->sighand->siglock);
1926 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1927 spin_unlock_irq(¤t->sighand->siglock);
1928}
1929
1930/**
1931 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1932 * @signr: signr causing group stop if initiating
1933 *
1934 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1935 * and participate in it. If already set, participate in the existing
1936 * group stop. If participated in a group stop (and thus slept), %true is
1937 * returned with siglock released.
1938 *
1939 * If ptraced, this function doesn't handle stop itself. Instead,
1940 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1941 * untouched. The caller must ensure that INTERRUPT trap handling takes
1942 * places afterwards.
1943 *
1944 * CONTEXT:
1945 * Must be called with @current->sighand->siglock held, which is released
1946 * on %true return.
1947 *
1948 * RETURNS:
1949 * %false if group stop is already cancelled or ptrace trap is scheduled.
1950 * %true if participated in group stop.
1951 */
1952static bool do_signal_stop(int signr)
1953 __releases(¤t->sighand->siglock)
1954{
1955 struct signal_struct *sig = current->signal;
1956
1957 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1958 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1959 struct task_struct *t;
1960
1961 /* signr will be recorded in task->jobctl for retries */
1962 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1963
1964 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1965 unlikely(signal_group_exit(sig)))
1966 return false;
1967 /*
1968 * There is no group stop already in progress. We must
1969 * initiate one now.
1970 *
1971 * While ptraced, a task may be resumed while group stop is
1972 * still in effect and then receive a stop signal and
1973 * initiate another group stop. This deviates from the
1974 * usual behavior as two consecutive stop signals can't
1975 * cause two group stops when !ptraced. That is why we
1976 * also check !task_is_stopped(t) below.
1977 *
1978 * The condition can be distinguished by testing whether
1979 * SIGNAL_STOP_STOPPED is already set. Don't generate
1980 * group_exit_code in such case.
1981 *
1982 * This is not necessary for SIGNAL_STOP_CONTINUED because
1983 * an intervening stop signal is required to cause two
1984 * continued events regardless of ptrace.
1985 */
1986 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1987 sig->group_exit_code = signr;
1988
1989 sig->group_stop_count = 0;
1990
1991 if (task_set_jobctl_pending(current, signr | gstop))
1992 sig->group_stop_count++;
1993
1994 t = current;
1995 while_each_thread(current, t) {
1996 /*
1997 * Setting state to TASK_STOPPED for a group
1998 * stop is always done with the siglock held,
1999 * so this check has no races.
2000 */
2001 if (!task_is_stopped(t) &&
2002 task_set_jobctl_pending(t, signr | gstop)) {
2003 sig->group_stop_count++;
2004 if (likely(!(t->ptrace & PT_SEIZED)))
2005 signal_wake_up(t, 0);
2006 else
2007 ptrace_trap_notify(t);
2008 }
2009 }
2010 }
2011
2012 if (likely(!current->ptrace)) {
2013 int notify = 0;
2014
2015 /*
2016 * If there are no other threads in the group, or if there
2017 * is a group stop in progress and we are the last to stop,
2018 * report to the parent.
2019 */
2020 if (task_participate_group_stop(current))
2021 notify = CLD_STOPPED;
2022
2023 __set_current_state(TASK_STOPPED);
2024 spin_unlock_irq(¤t->sighand->siglock);
2025
2026 /*
2027 * Notify the parent of the group stop completion. Because
2028 * we're not holding either the siglock or tasklist_lock
2029 * here, ptracer may attach inbetween; however, this is for
2030 * group stop and should always be delivered to the real
2031 * parent of the group leader. The new ptracer will get
2032 * its notification when this task transitions into
2033 * TASK_TRACED.
2034 */
2035 if (notify) {
2036 read_lock(&tasklist_lock);
2037 do_notify_parent_cldstop(current, false, notify);
2038 read_unlock(&tasklist_lock);
2039 }
2040
2041 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2042 freezable_schedule();
2043 return true;
2044 } else {
2045 /*
2046 * While ptraced, group stop is handled by STOP trap.
2047 * Schedule it and let the caller deal with it.
2048 */
2049 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2050 return false;
2051 }
2052}
2053
2054/**
2055 * do_jobctl_trap - take care of ptrace jobctl traps
2056 *
2057 * When PT_SEIZED, it's used for both group stop and explicit
2058 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2059 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2060 * the stop signal; otherwise, %SIGTRAP.
2061 *
2062 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2063 * number as exit_code and no siginfo.
2064 *
2065 * CONTEXT:
2066 * Must be called with @current->sighand->siglock held, which may be
2067 * released and re-acquired before returning with intervening sleep.
2068 */
2069static void do_jobctl_trap(void)
2070{
2071 struct signal_struct *signal = current->signal;
2072 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2073
2074 if (current->ptrace & PT_SEIZED) {
2075 if (!signal->group_stop_count &&
2076 !(signal->flags & SIGNAL_STOP_STOPPED))
2077 signr = SIGTRAP;
2078 WARN_ON_ONCE(!signr);
2079 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2080 CLD_STOPPED);
2081 } else {
2082 WARN_ON_ONCE(!signr);
2083 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2084 current->exit_code = 0;
2085 }
2086}
2087
2088static int ptrace_signal(int signr, siginfo_t *info)
2089{
2090 ptrace_signal_deliver();
2091 /*
2092 * We do not check sig_kernel_stop(signr) but set this marker
2093 * unconditionally because we do not know whether debugger will
2094 * change signr. This flag has no meaning unless we are going
2095 * to stop after return from ptrace_stop(). In this case it will
2096 * be checked in do_signal_stop(), we should only stop if it was
2097 * not cleared by SIGCONT while we were sleeping. See also the
2098 * comment in dequeue_signal().
2099 */
2100 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2101 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2102
2103 /* We're back. Did the debugger cancel the sig? */
2104 signr = current->exit_code;
2105 if (signr == 0)
2106 return signr;
2107
2108 current->exit_code = 0;
2109
2110 /*
2111 * Update the siginfo structure if the signal has
2112 * changed. If the debugger wanted something
2113 * specific in the siginfo structure then it should
2114 * have updated *info via PTRACE_SETSIGINFO.
2115 */
2116 if (signr != info->si_signo) {
2117 info->si_signo = signr;
2118 info->si_errno = 0;
2119 info->si_code = SI_USER;
2120 rcu_read_lock();
2121 info->si_pid = task_pid_vnr(current->parent);
2122 info->si_uid = from_kuid_munged(current_user_ns(),
2123 task_uid(current->parent));
2124 rcu_read_unlock();
2125 }
2126
2127 /* If the (new) signal is now blocked, requeue it. */
2128 if (sigismember(¤t->blocked, signr)) {
2129 specific_send_sig_info(signr, info, current);
2130 signr = 0;
2131 }
2132
2133 return signr;
2134}
2135
2136int get_signal(struct ksignal *ksig)
2137{
2138 struct sighand_struct *sighand = current->sighand;
2139 struct signal_struct *signal = current->signal;
2140 int signr;
2141
2142 if (unlikely(current->task_works))
2143 task_work_run();
2144
2145 if (unlikely(uprobe_deny_signal()))
2146 return 0;
2147
2148 /*
2149 * Do this once, we can't return to user-mode if freezing() == T.
2150 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2151 * thus do not need another check after return.
2152 */
2153 try_to_freeze();
2154
2155relock:
2156 spin_lock_irq(&sighand->siglock);
2157 /*
2158 * Every stopped thread goes here after wakeup. Check to see if
2159 * we should notify the parent, prepare_signal(SIGCONT) encodes
2160 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2161 */
2162 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2163 int why;
2164
2165 if (signal->flags & SIGNAL_CLD_CONTINUED)
2166 why = CLD_CONTINUED;
2167 else
2168 why = CLD_STOPPED;
2169
2170 signal->flags &= ~SIGNAL_CLD_MASK;
2171
2172 spin_unlock_irq(&sighand->siglock);
2173
2174 /*
2175 * Notify the parent that we're continuing. This event is
2176 * always per-process and doesn't make whole lot of sense
2177 * for ptracers, who shouldn't consume the state via
2178 * wait(2) either, but, for backward compatibility, notify
2179 * the ptracer of the group leader too unless it's gonna be
2180 * a duplicate.
2181 */
2182 read_lock(&tasklist_lock);
2183 do_notify_parent_cldstop(current, false, why);
2184
2185 if (ptrace_reparented(current->group_leader))
2186 do_notify_parent_cldstop(current->group_leader,
2187 true, why);
2188 read_unlock(&tasklist_lock);
2189
2190 goto relock;
2191 }
2192
2193 for (;;) {
2194 struct k_sigaction *ka;
2195
2196 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2197 do_signal_stop(0))
2198 goto relock;
2199
2200 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2201 do_jobctl_trap();
2202 spin_unlock_irq(&sighand->siglock);
2203 goto relock;
2204 }
2205
2206 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2207
2208 if (!signr)
2209 break; /* will return 0 */
2210
2211 if (unlikely(current->ptrace) && signr != SIGKILL) {
2212 signr = ptrace_signal(signr, &ksig->info);
2213 if (!signr)
2214 continue;
2215 }
2216
2217 ka = &sighand->action[signr-1];
2218
2219 /* Trace actually delivered signals. */
2220 trace_signal_deliver(signr, &ksig->info, ka);
2221
2222 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2223 continue;
2224 if (ka->sa.sa_handler != SIG_DFL) {
2225 /* Run the handler. */
2226 ksig->ka = *ka;
2227
2228 if (ka->sa.sa_flags & SA_ONESHOT)
2229 ka->sa.sa_handler = SIG_DFL;
2230
2231 break; /* will return non-zero "signr" value */
2232 }
2233
2234 /*
2235 * Now we are doing the default action for this signal.
2236 */
2237 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2238 continue;
2239
2240 /*
2241 * Global init gets no signals it doesn't want.
2242 * Container-init gets no signals it doesn't want from same
2243 * container.
2244 *
2245 * Note that if global/container-init sees a sig_kernel_only()
2246 * signal here, the signal must have been generated internally
2247 * or must have come from an ancestor namespace. In either
2248 * case, the signal cannot be dropped.
2249 */
2250 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2251 !sig_kernel_only(signr))
2252 continue;
2253
2254 if (sig_kernel_stop(signr)) {
2255 /*
2256 * The default action is to stop all threads in
2257 * the thread group. The job control signals
2258 * do nothing in an orphaned pgrp, but SIGSTOP
2259 * always works. Note that siglock needs to be
2260 * dropped during the call to is_orphaned_pgrp()
2261 * because of lock ordering with tasklist_lock.
2262 * This allows an intervening SIGCONT to be posted.
2263 * We need to check for that and bail out if necessary.
2264 */
2265 if (signr != SIGSTOP) {
2266 spin_unlock_irq(&sighand->siglock);
2267
2268 /* signals can be posted during this window */
2269
2270 if (is_current_pgrp_orphaned())
2271 goto relock;
2272
2273 spin_lock_irq(&sighand->siglock);
2274 }
2275
2276 if (likely(do_signal_stop(ksig->info.si_signo))) {
2277 /* It released the siglock. */
2278 goto relock;
2279 }
2280
2281 /*
2282 * We didn't actually stop, due to a race
2283 * with SIGCONT or something like that.
2284 */
2285 continue;
2286 }
2287
2288 spin_unlock_irq(&sighand->siglock);
2289
2290 /*
2291 * Anything else is fatal, maybe with a core dump.
2292 */
2293 current->flags |= PF_SIGNALED;
2294
2295 if (sig_kernel_coredump(signr)) {
2296 if (print_fatal_signals)
2297 print_fatal_signal(ksig->info.si_signo);
2298 proc_coredump_connector(current);
2299 /*
2300 * If it was able to dump core, this kills all
2301 * other threads in the group and synchronizes with
2302 * their demise. If we lost the race with another
2303 * thread getting here, it set group_exit_code
2304 * first and our do_group_exit call below will use
2305 * that value and ignore the one we pass it.
2306 */
2307 do_coredump(&ksig->info);
2308 }
2309
2310 /*
2311 * Death signals, no core dump.
2312 */
2313 do_group_exit(ksig->info.si_signo);
2314 /* NOTREACHED */
2315 }
2316 spin_unlock_irq(&sighand->siglock);
2317
2318 ksig->sig = signr;
2319 return ksig->sig > 0;
2320}
2321
2322/**
2323 * signal_delivered -
2324 * @ksig: kernel signal struct
2325 * @stepping: nonzero if debugger single-step or block-step in use
2326 *
2327 * This function should be called when a signal has successfully been
2328 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2329 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2330 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2331 */
2332static void signal_delivered(struct ksignal *ksig, int stepping)
2333{
2334 sigset_t blocked;
2335
2336 /* A signal was successfully delivered, and the
2337 saved sigmask was stored on the signal frame,
2338 and will be restored by sigreturn. So we can
2339 simply clear the restore sigmask flag. */
2340 clear_restore_sigmask();
2341
2342 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2343 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2344 sigaddset(&blocked, ksig->sig);
2345 set_current_blocked(&blocked);
2346 tracehook_signal_handler(stepping);
2347}
2348
2349void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2350{
2351 if (failed)
2352 force_sigsegv(ksig->sig, current);
2353 else
2354 signal_delivered(ksig, stepping);
2355}
2356
2357/*
2358 * It could be that complete_signal() picked us to notify about the
2359 * group-wide signal. Other threads should be notified now to take
2360 * the shared signals in @which since we will not.
2361 */
2362static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2363{
2364 sigset_t retarget;
2365 struct task_struct *t;
2366
2367 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2368 if (sigisemptyset(&retarget))
2369 return;
2370
2371 t = tsk;
2372 while_each_thread(tsk, t) {
2373 if (t->flags & PF_EXITING)
2374 continue;
2375
2376 if (!has_pending_signals(&retarget, &t->blocked))
2377 continue;
2378 /* Remove the signals this thread can handle. */
2379 sigandsets(&retarget, &retarget, &t->blocked);
2380
2381 if (!signal_pending(t))
2382 signal_wake_up(t, 0);
2383
2384 if (sigisemptyset(&retarget))
2385 break;
2386 }
2387}
2388
2389void exit_signals(struct task_struct *tsk)
2390{
2391 int group_stop = 0;
2392 sigset_t unblocked;
2393
2394 /*
2395 * @tsk is about to have PF_EXITING set - lock out users which
2396 * expect stable threadgroup.
2397 */
2398 threadgroup_change_begin(tsk);
2399
2400 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2401 tsk->flags |= PF_EXITING;
2402 threadgroup_change_end(tsk);
2403 return;
2404 }
2405
2406 spin_lock_irq(&tsk->sighand->siglock);
2407 /*
2408 * From now this task is not visible for group-wide signals,
2409 * see wants_signal(), do_signal_stop().
2410 */
2411 tsk->flags |= PF_EXITING;
2412
2413 threadgroup_change_end(tsk);
2414
2415 if (!signal_pending(tsk))
2416 goto out;
2417
2418 unblocked = tsk->blocked;
2419 signotset(&unblocked);
2420 retarget_shared_pending(tsk, &unblocked);
2421
2422 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2423 task_participate_group_stop(tsk))
2424 group_stop = CLD_STOPPED;
2425out:
2426 spin_unlock_irq(&tsk->sighand->siglock);
2427
2428 /*
2429 * If group stop has completed, deliver the notification. This
2430 * should always go to the real parent of the group leader.
2431 */
2432 if (unlikely(group_stop)) {
2433 read_lock(&tasklist_lock);
2434 do_notify_parent_cldstop(tsk, false, group_stop);
2435 read_unlock(&tasklist_lock);
2436 }
2437}
2438
2439EXPORT_SYMBOL(recalc_sigpending);
2440EXPORT_SYMBOL_GPL(dequeue_signal);
2441EXPORT_SYMBOL(flush_signals);
2442EXPORT_SYMBOL(force_sig);
2443EXPORT_SYMBOL(send_sig);
2444EXPORT_SYMBOL(send_sig_info);
2445EXPORT_SYMBOL(sigprocmask);
2446
2447/*
2448 * System call entry points.
2449 */
2450
2451/**
2452 * sys_restart_syscall - restart a system call
2453 */
2454SYSCALL_DEFINE0(restart_syscall)
2455{
2456 struct restart_block *restart = ¤t->restart_block;
2457 return restart->fn(restart);
2458}
2459
2460long do_no_restart_syscall(struct restart_block *param)
2461{
2462 return -EINTR;
2463}
2464
2465static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2466{
2467 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2468 sigset_t newblocked;
2469 /* A set of now blocked but previously unblocked signals. */
2470 sigandnsets(&newblocked, newset, ¤t->blocked);
2471 retarget_shared_pending(tsk, &newblocked);
2472 }
2473 tsk->blocked = *newset;
2474 recalc_sigpending();
2475}
2476
2477/**
2478 * set_current_blocked - change current->blocked mask
2479 * @newset: new mask
2480 *
2481 * It is wrong to change ->blocked directly, this helper should be used
2482 * to ensure the process can't miss a shared signal we are going to block.
2483 */
2484void set_current_blocked(sigset_t *newset)
2485{
2486 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2487 __set_current_blocked(newset);
2488}
2489
2490void __set_current_blocked(const sigset_t *newset)
2491{
2492 struct task_struct *tsk = current;
2493
2494 /*
2495 * In case the signal mask hasn't changed, there is nothing we need
2496 * to do. The current->blocked shouldn't be modified by other task.
2497 */
2498 if (sigequalsets(&tsk->blocked, newset))
2499 return;
2500
2501 spin_lock_irq(&tsk->sighand->siglock);
2502 __set_task_blocked(tsk, newset);
2503 spin_unlock_irq(&tsk->sighand->siglock);
2504}
2505
2506/*
2507 * This is also useful for kernel threads that want to temporarily
2508 * (or permanently) block certain signals.
2509 *
2510 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2511 * interface happily blocks "unblockable" signals like SIGKILL
2512 * and friends.
2513 */
2514int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2515{
2516 struct task_struct *tsk = current;
2517 sigset_t newset;
2518
2519 /* Lockless, only current can change ->blocked, never from irq */
2520 if (oldset)
2521 *oldset = tsk->blocked;
2522
2523 switch (how) {
2524 case SIG_BLOCK:
2525 sigorsets(&newset, &tsk->blocked, set);
2526 break;
2527 case SIG_UNBLOCK:
2528 sigandnsets(&newset, &tsk->blocked, set);
2529 break;
2530 case SIG_SETMASK:
2531 newset = *set;
2532 break;
2533 default:
2534 return -EINVAL;
2535 }
2536
2537 __set_current_blocked(&newset);
2538 return 0;
2539}
2540
2541/**
2542 * sys_rt_sigprocmask - change the list of currently blocked signals
2543 * @how: whether to add, remove, or set signals
2544 * @nset: stores pending signals
2545 * @oset: previous value of signal mask if non-null
2546 * @sigsetsize: size of sigset_t type
2547 */
2548SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2549 sigset_t __user *, oset, size_t, sigsetsize)
2550{
2551 sigset_t old_set, new_set;
2552 int error;
2553
2554 /* XXX: Don't preclude handling different sized sigset_t's. */
2555 if (sigsetsize != sizeof(sigset_t))
2556 return -EINVAL;
2557
2558 old_set = current->blocked;
2559
2560 if (nset) {
2561 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2562 return -EFAULT;
2563 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2564
2565 error = sigprocmask(how, &new_set, NULL);
2566 if (error)
2567 return error;
2568 }
2569
2570 if (oset) {
2571 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2572 return -EFAULT;
2573 }
2574
2575 return 0;
2576}
2577
2578#ifdef CONFIG_COMPAT
2579COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2580 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2581{
2582#ifdef __BIG_ENDIAN
2583 sigset_t old_set = current->blocked;
2584
2585 /* XXX: Don't preclude handling different sized sigset_t's. */
2586 if (sigsetsize != sizeof(sigset_t))
2587 return -EINVAL;
2588
2589 if (nset) {
2590 compat_sigset_t new32;
2591 sigset_t new_set;
2592 int error;
2593 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2594 return -EFAULT;
2595
2596 sigset_from_compat(&new_set, &new32);
2597 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2598
2599 error = sigprocmask(how, &new_set, NULL);
2600 if (error)
2601 return error;
2602 }
2603 if (oset) {
2604 compat_sigset_t old32;
2605 sigset_to_compat(&old32, &old_set);
2606 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2607 return -EFAULT;
2608 }
2609 return 0;
2610#else
2611 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2612 (sigset_t __user *)oset, sigsetsize);
2613#endif
2614}
2615#endif
2616
2617static int do_sigpending(void *set, unsigned long sigsetsize)
2618{
2619 if (sigsetsize > sizeof(sigset_t))
2620 return -EINVAL;
2621
2622 spin_lock_irq(¤t->sighand->siglock);
2623 sigorsets(set, ¤t->pending.signal,
2624 ¤t->signal->shared_pending.signal);
2625 spin_unlock_irq(¤t->sighand->siglock);
2626
2627 /* Outside the lock because only this thread touches it. */
2628 sigandsets(set, ¤t->blocked, set);
2629 return 0;
2630}
2631
2632/**
2633 * sys_rt_sigpending - examine a pending signal that has been raised
2634 * while blocked
2635 * @uset: stores pending signals
2636 * @sigsetsize: size of sigset_t type or larger
2637 */
2638SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2639{
2640 sigset_t set;
2641 int err = do_sigpending(&set, sigsetsize);
2642 if (!err && copy_to_user(uset, &set, sigsetsize))
2643 err = -EFAULT;
2644 return err;
2645}
2646
2647#ifdef CONFIG_COMPAT
2648COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2649 compat_size_t, sigsetsize)
2650{
2651#ifdef __BIG_ENDIAN
2652 sigset_t set;
2653 int err = do_sigpending(&set, sigsetsize);
2654 if (!err) {
2655 compat_sigset_t set32;
2656 sigset_to_compat(&set32, &set);
2657 /* we can get here only if sigsetsize <= sizeof(set) */
2658 if (copy_to_user(uset, &set32, sigsetsize))
2659 err = -EFAULT;
2660 }
2661 return err;
2662#else
2663 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2664#endif
2665}
2666#endif
2667
2668#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2669
2670int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2671{
2672 int err;
2673
2674 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2675 return -EFAULT;
2676 if (from->si_code < 0)
2677 return __copy_to_user(to, from, sizeof(siginfo_t))
2678 ? -EFAULT : 0;
2679 /*
2680 * If you change siginfo_t structure, please be sure
2681 * this code is fixed accordingly.
2682 * Please remember to update the signalfd_copyinfo() function
2683 * inside fs/signalfd.c too, in case siginfo_t changes.
2684 * It should never copy any pad contained in the structure
2685 * to avoid security leaks, but must copy the generic
2686 * 3 ints plus the relevant union member.
2687 */
2688 err = __put_user(from->si_signo, &to->si_signo);
2689 err |= __put_user(from->si_errno, &to->si_errno);
2690 err |= __put_user((short)from->si_code, &to->si_code);
2691 switch (from->si_code & __SI_MASK) {
2692 case __SI_KILL:
2693 err |= __put_user(from->si_pid, &to->si_pid);
2694 err |= __put_user(from->si_uid, &to->si_uid);
2695 break;
2696 case __SI_TIMER:
2697 err |= __put_user(from->si_tid, &to->si_tid);
2698 err |= __put_user(from->si_overrun, &to->si_overrun);
2699 err |= __put_user(from->si_ptr, &to->si_ptr);
2700 break;
2701 case __SI_POLL:
2702 err |= __put_user(from->si_band, &to->si_band);
2703 err |= __put_user(from->si_fd, &to->si_fd);
2704 break;
2705 case __SI_FAULT:
2706 err |= __put_user(from->si_addr, &to->si_addr);
2707#ifdef __ARCH_SI_TRAPNO
2708 err |= __put_user(from->si_trapno, &to->si_trapno);
2709#endif
2710#ifdef BUS_MCEERR_AO
2711 /*
2712 * Other callers might not initialize the si_lsb field,
2713 * so check explicitly for the right codes here.
2714 */
2715 if (from->si_signo == SIGBUS &&
2716 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2717 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2718#endif
2719#ifdef SEGV_BNDERR
2720 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2721 err |= __put_user(from->si_lower, &to->si_lower);
2722 err |= __put_user(from->si_upper, &to->si_upper);
2723 }
2724#endif
2725#ifdef SEGV_PKUERR
2726 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2727 err |= __put_user(from->si_pkey, &to->si_pkey);
2728#endif
2729 break;
2730 case __SI_CHLD:
2731 err |= __put_user(from->si_pid, &to->si_pid);
2732 err |= __put_user(from->si_uid, &to->si_uid);
2733 err |= __put_user(from->si_status, &to->si_status);
2734 err |= __put_user(from->si_utime, &to->si_utime);
2735 err |= __put_user(from->si_stime, &to->si_stime);
2736 break;
2737 case __SI_RT: /* This is not generated by the kernel as of now. */
2738 case __SI_MESGQ: /* But this is */
2739 err |= __put_user(from->si_pid, &to->si_pid);
2740 err |= __put_user(from->si_uid, &to->si_uid);
2741 err |= __put_user(from->si_ptr, &to->si_ptr);
2742 break;
2743#ifdef __ARCH_SIGSYS
2744 case __SI_SYS:
2745 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2746 err |= __put_user(from->si_syscall, &to->si_syscall);
2747 err |= __put_user(from->si_arch, &to->si_arch);
2748 break;
2749#endif
2750 default: /* this is just in case for now ... */
2751 err |= __put_user(from->si_pid, &to->si_pid);
2752 err |= __put_user(from->si_uid, &to->si_uid);
2753 break;
2754 }
2755 return err;
2756}
2757
2758#endif
2759
2760/**
2761 * do_sigtimedwait - wait for queued signals specified in @which
2762 * @which: queued signals to wait for
2763 * @info: if non-null, the signal's siginfo is returned here
2764 * @ts: upper bound on process time suspension
2765 */
2766int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2767 const struct timespec *ts)
2768{
2769 ktime_t *to = NULL, timeout = KTIME_MAX;
2770 struct task_struct *tsk = current;
2771 sigset_t mask = *which;
2772 int sig, ret = 0;
2773
2774 if (ts) {
2775 if (!timespec_valid(ts))
2776 return -EINVAL;
2777 timeout = timespec_to_ktime(*ts);
2778 to = &timeout;
2779 }
2780
2781 /*
2782 * Invert the set of allowed signals to get those we want to block.
2783 */
2784 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2785 signotset(&mask);
2786
2787 spin_lock_irq(&tsk->sighand->siglock);
2788 sig = dequeue_signal(tsk, &mask, info);
2789 if (!sig && timeout) {
2790 /*
2791 * None ready, temporarily unblock those we're interested
2792 * while we are sleeping in so that we'll be awakened when
2793 * they arrive. Unblocking is always fine, we can avoid
2794 * set_current_blocked().
2795 */
2796 tsk->real_blocked = tsk->blocked;
2797 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2798 recalc_sigpending();
2799 spin_unlock_irq(&tsk->sighand->siglock);
2800
2801 __set_current_state(TASK_INTERRUPTIBLE);
2802 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
2803 HRTIMER_MODE_REL);
2804 spin_lock_irq(&tsk->sighand->siglock);
2805 __set_task_blocked(tsk, &tsk->real_blocked);
2806 sigemptyset(&tsk->real_blocked);
2807 sig = dequeue_signal(tsk, &mask, info);
2808 }
2809 spin_unlock_irq(&tsk->sighand->siglock);
2810
2811 if (sig)
2812 return sig;
2813 return ret ? -EINTR : -EAGAIN;
2814}
2815
2816/**
2817 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2818 * in @uthese
2819 * @uthese: queued signals to wait for
2820 * @uinfo: if non-null, the signal's siginfo is returned here
2821 * @uts: upper bound on process time suspension
2822 * @sigsetsize: size of sigset_t type
2823 */
2824SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2825 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2826 size_t, sigsetsize)
2827{
2828 sigset_t these;
2829 struct timespec ts;
2830 siginfo_t info;
2831 int ret;
2832
2833 /* XXX: Don't preclude handling different sized sigset_t's. */
2834 if (sigsetsize != sizeof(sigset_t))
2835 return -EINVAL;
2836
2837 if (copy_from_user(&these, uthese, sizeof(these)))
2838 return -EFAULT;
2839
2840 if (uts) {
2841 if (copy_from_user(&ts, uts, sizeof(ts)))
2842 return -EFAULT;
2843 }
2844
2845 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2846
2847 if (ret > 0 && uinfo) {
2848 if (copy_siginfo_to_user(uinfo, &info))
2849 ret = -EFAULT;
2850 }
2851
2852 return ret;
2853}
2854
2855/**
2856 * sys_kill - send a signal to a process
2857 * @pid: the PID of the process
2858 * @sig: signal to be sent
2859 */
2860SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2861{
2862 struct siginfo info;
2863
2864 info.si_signo = sig;
2865 info.si_errno = 0;
2866 info.si_code = SI_USER;
2867 info.si_pid = task_tgid_vnr(current);
2868 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2869
2870 return kill_something_info(sig, &info, pid);
2871}
2872
2873static int
2874do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2875{
2876 struct task_struct *p;
2877 int error = -ESRCH;
2878
2879 rcu_read_lock();
2880 p = find_task_by_vpid(pid);
2881 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2882 error = check_kill_permission(sig, info, p);
2883 /*
2884 * The null signal is a permissions and process existence
2885 * probe. No signal is actually delivered.
2886 */
2887 if (!error && sig) {
2888 error = do_send_sig_info(sig, info, p, false);
2889 /*
2890 * If lock_task_sighand() failed we pretend the task
2891 * dies after receiving the signal. The window is tiny,
2892 * and the signal is private anyway.
2893 */
2894 if (unlikely(error == -ESRCH))
2895 error = 0;
2896 }
2897 }
2898 rcu_read_unlock();
2899
2900 return error;
2901}
2902
2903static int do_tkill(pid_t tgid, pid_t pid, int sig)
2904{
2905 struct siginfo info = {};
2906
2907 info.si_signo = sig;
2908 info.si_errno = 0;
2909 info.si_code = SI_TKILL;
2910 info.si_pid = task_tgid_vnr(current);
2911 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2912
2913 return do_send_specific(tgid, pid, sig, &info);
2914}
2915
2916/**
2917 * sys_tgkill - send signal to one specific thread
2918 * @tgid: the thread group ID of the thread
2919 * @pid: the PID of the thread
2920 * @sig: signal to be sent
2921 *
2922 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2923 * exists but it's not belonging to the target process anymore. This
2924 * method solves the problem of threads exiting and PIDs getting reused.
2925 */
2926SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2927{
2928 /* This is only valid for single tasks */
2929 if (pid <= 0 || tgid <= 0)
2930 return -EINVAL;
2931
2932 return do_tkill(tgid, pid, sig);
2933}
2934
2935/**
2936 * sys_tkill - send signal to one specific task
2937 * @pid: the PID of the task
2938 * @sig: signal to be sent
2939 *
2940 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2941 */
2942SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2943{
2944 /* This is only valid for single tasks */
2945 if (pid <= 0)
2946 return -EINVAL;
2947
2948 return do_tkill(0, pid, sig);
2949}
2950
2951static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2952{
2953 /* Not even root can pretend to send signals from the kernel.
2954 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2955 */
2956 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2957 (task_pid_vnr(current) != pid))
2958 return -EPERM;
2959
2960 info->si_signo = sig;
2961
2962 /* POSIX.1b doesn't mention process groups. */
2963 return kill_proc_info(sig, info, pid);
2964}
2965
2966/**
2967 * sys_rt_sigqueueinfo - send signal information to a signal
2968 * @pid: the PID of the thread
2969 * @sig: signal to be sent
2970 * @uinfo: signal info to be sent
2971 */
2972SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2973 siginfo_t __user *, uinfo)
2974{
2975 siginfo_t info;
2976 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2977 return -EFAULT;
2978 return do_rt_sigqueueinfo(pid, sig, &info);
2979}
2980
2981#ifdef CONFIG_COMPAT
2982COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
2983 compat_pid_t, pid,
2984 int, sig,
2985 struct compat_siginfo __user *, uinfo)
2986{
2987 siginfo_t info = {};
2988 int ret = copy_siginfo_from_user32(&info, uinfo);
2989 if (unlikely(ret))
2990 return ret;
2991 return do_rt_sigqueueinfo(pid, sig, &info);
2992}
2993#endif
2994
2995static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2996{
2997 /* This is only valid for single tasks */
2998 if (pid <= 0 || tgid <= 0)
2999 return -EINVAL;
3000
3001 /* Not even root can pretend to send signals from the kernel.
3002 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3003 */
3004 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3005 (task_pid_vnr(current) != pid))
3006 return -EPERM;
3007
3008 info->si_signo = sig;
3009
3010 return do_send_specific(tgid, pid, sig, info);
3011}
3012
3013SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3014 siginfo_t __user *, uinfo)
3015{
3016 siginfo_t info;
3017
3018 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3019 return -EFAULT;
3020
3021 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3022}
3023
3024#ifdef CONFIG_COMPAT
3025COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3026 compat_pid_t, tgid,
3027 compat_pid_t, pid,
3028 int, sig,
3029 struct compat_siginfo __user *, uinfo)
3030{
3031 siginfo_t info = {};
3032
3033 if (copy_siginfo_from_user32(&info, uinfo))
3034 return -EFAULT;
3035 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3036}
3037#endif
3038
3039/*
3040 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3041 */
3042void kernel_sigaction(int sig, __sighandler_t action)
3043{
3044 spin_lock_irq(¤t->sighand->siglock);
3045 current->sighand->action[sig - 1].sa.sa_handler = action;
3046 if (action == SIG_IGN) {
3047 sigset_t mask;
3048
3049 sigemptyset(&mask);
3050 sigaddset(&mask, sig);
3051
3052 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3053 flush_sigqueue_mask(&mask, ¤t->pending);
3054 recalc_sigpending();
3055 }
3056 spin_unlock_irq(¤t->sighand->siglock);
3057}
3058EXPORT_SYMBOL(kernel_sigaction);
3059
3060void __weak sigaction_compat_abi(struct k_sigaction *act,
3061 struct k_sigaction *oact)
3062{
3063}
3064
3065int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3066{
3067 struct task_struct *p = current, *t;
3068 struct k_sigaction *k;
3069 sigset_t mask;
3070
3071 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3072 return -EINVAL;
3073
3074 k = &p->sighand->action[sig-1];
3075
3076 spin_lock_irq(&p->sighand->siglock);
3077 if (oact)
3078 *oact = *k;
3079
3080 sigaction_compat_abi(act, oact);
3081
3082 if (act) {
3083 sigdelsetmask(&act->sa.sa_mask,
3084 sigmask(SIGKILL) | sigmask(SIGSTOP));
3085 *k = *act;
3086 /*
3087 * POSIX 3.3.1.3:
3088 * "Setting a signal action to SIG_IGN for a signal that is
3089 * pending shall cause the pending signal to be discarded,
3090 * whether or not it is blocked."
3091 *
3092 * "Setting a signal action to SIG_DFL for a signal that is
3093 * pending and whose default action is to ignore the signal
3094 * (for example, SIGCHLD), shall cause the pending signal to
3095 * be discarded, whether or not it is blocked"
3096 */
3097 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3098 sigemptyset(&mask);
3099 sigaddset(&mask, sig);
3100 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3101 for_each_thread(p, t)
3102 flush_sigqueue_mask(&mask, &t->pending);
3103 }
3104 }
3105
3106 spin_unlock_irq(&p->sighand->siglock);
3107 return 0;
3108}
3109
3110static int
3111do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3112{
3113 stack_t oss;
3114 int error;
3115
3116 oss.ss_sp = (void __user *) current->sas_ss_sp;
3117 oss.ss_size = current->sas_ss_size;
3118 oss.ss_flags = sas_ss_flags(sp) |
3119 (current->sas_ss_flags & SS_FLAG_BITS);
3120
3121 if (uss) {
3122 void __user *ss_sp;
3123 size_t ss_size;
3124 unsigned ss_flags;
3125 int ss_mode;
3126
3127 error = -EFAULT;
3128 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3129 goto out;
3130 error = __get_user(ss_sp, &uss->ss_sp) |
3131 __get_user(ss_flags, &uss->ss_flags) |
3132 __get_user(ss_size, &uss->ss_size);
3133 if (error)
3134 goto out;
3135
3136 error = -EPERM;
3137 if (on_sig_stack(sp))
3138 goto out;
3139
3140 ss_mode = ss_flags & ~SS_FLAG_BITS;
3141 error = -EINVAL;
3142 if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3143 ss_mode != 0)
3144 goto out;
3145
3146 if (ss_mode == SS_DISABLE) {
3147 ss_size = 0;
3148 ss_sp = NULL;
3149 } else {
3150 error = -ENOMEM;
3151 if (ss_size < MINSIGSTKSZ)
3152 goto out;
3153 }
3154
3155 current->sas_ss_sp = (unsigned long) ss_sp;
3156 current->sas_ss_size = ss_size;
3157 current->sas_ss_flags = ss_flags;
3158 }
3159
3160 error = 0;
3161 if (uoss) {
3162 error = -EFAULT;
3163 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3164 goto out;
3165 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3166 __put_user(oss.ss_size, &uoss->ss_size) |
3167 __put_user(oss.ss_flags, &uoss->ss_flags);
3168 }
3169
3170out:
3171 return error;
3172}
3173SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3174{
3175 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3176}
3177
3178int restore_altstack(const stack_t __user *uss)
3179{
3180 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3181 /* squash all but EFAULT for now */
3182 return err == -EFAULT ? err : 0;
3183}
3184
3185int __save_altstack(stack_t __user *uss, unsigned long sp)
3186{
3187 struct task_struct *t = current;
3188 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3189 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3190 __put_user(t->sas_ss_size, &uss->ss_size);
3191 if (err)
3192 return err;
3193 if (t->sas_ss_flags & SS_AUTODISARM)
3194 sas_ss_reset(t);
3195 return 0;
3196}
3197
3198#ifdef CONFIG_COMPAT
3199COMPAT_SYSCALL_DEFINE2(sigaltstack,
3200 const compat_stack_t __user *, uss_ptr,
3201 compat_stack_t __user *, uoss_ptr)
3202{
3203 stack_t uss, uoss;
3204 int ret;
3205 mm_segment_t seg;
3206
3207 if (uss_ptr) {
3208 compat_stack_t uss32;
3209
3210 memset(&uss, 0, sizeof(stack_t));
3211 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3212 return -EFAULT;
3213 uss.ss_sp = compat_ptr(uss32.ss_sp);
3214 uss.ss_flags = uss32.ss_flags;
3215 uss.ss_size = uss32.ss_size;
3216 }
3217 seg = get_fs();
3218 set_fs(KERNEL_DS);
3219 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3220 (stack_t __force __user *) &uoss,
3221 compat_user_stack_pointer());
3222 set_fs(seg);
3223 if (ret >= 0 && uoss_ptr) {
3224 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3225 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3226 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3227 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3228 ret = -EFAULT;
3229 }
3230 return ret;
3231}
3232
3233int compat_restore_altstack(const compat_stack_t __user *uss)
3234{
3235 int err = compat_sys_sigaltstack(uss, NULL);
3236 /* squash all but -EFAULT for now */
3237 return err == -EFAULT ? err : 0;
3238}
3239
3240int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3241{
3242 int err;
3243 struct task_struct *t = current;
3244 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3245 &uss->ss_sp) |
3246 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3247 __put_user(t->sas_ss_size, &uss->ss_size);
3248 if (err)
3249 return err;
3250 if (t->sas_ss_flags & SS_AUTODISARM)
3251 sas_ss_reset(t);
3252 return 0;
3253}
3254#endif
3255
3256#ifdef __ARCH_WANT_SYS_SIGPENDING
3257
3258/**
3259 * sys_sigpending - examine pending signals
3260 * @set: where mask of pending signal is returned
3261 */
3262SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3263{
3264 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3265}
3266
3267#endif
3268
3269#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3270/**
3271 * sys_sigprocmask - examine and change blocked signals
3272 * @how: whether to add, remove, or set signals
3273 * @nset: signals to add or remove (if non-null)
3274 * @oset: previous value of signal mask if non-null
3275 *
3276 * Some platforms have their own version with special arguments;
3277 * others support only sys_rt_sigprocmask.
3278 */
3279
3280SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3281 old_sigset_t __user *, oset)
3282{
3283 old_sigset_t old_set, new_set;
3284 sigset_t new_blocked;
3285
3286 old_set = current->blocked.sig[0];
3287
3288 if (nset) {
3289 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3290 return -EFAULT;
3291
3292 new_blocked = current->blocked;
3293
3294 switch (how) {
3295 case SIG_BLOCK:
3296 sigaddsetmask(&new_blocked, new_set);
3297 break;
3298 case SIG_UNBLOCK:
3299 sigdelsetmask(&new_blocked, new_set);
3300 break;
3301 case SIG_SETMASK:
3302 new_blocked.sig[0] = new_set;
3303 break;
3304 default:
3305 return -EINVAL;
3306 }
3307
3308 set_current_blocked(&new_blocked);
3309 }
3310
3311 if (oset) {
3312 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3313 return -EFAULT;
3314 }
3315
3316 return 0;
3317}
3318#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3319
3320#ifndef CONFIG_ODD_RT_SIGACTION
3321/**
3322 * sys_rt_sigaction - alter an action taken by a process
3323 * @sig: signal to be sent
3324 * @act: new sigaction
3325 * @oact: used to save the previous sigaction
3326 * @sigsetsize: size of sigset_t type
3327 */
3328SYSCALL_DEFINE4(rt_sigaction, int, sig,
3329 const struct sigaction __user *, act,
3330 struct sigaction __user *, oact,
3331 size_t, sigsetsize)
3332{
3333 struct k_sigaction new_sa, old_sa;
3334 int ret = -EINVAL;
3335
3336 /* XXX: Don't preclude handling different sized sigset_t's. */
3337 if (sigsetsize != sizeof(sigset_t))
3338 goto out;
3339
3340 if (act) {
3341 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3342 return -EFAULT;
3343 }
3344
3345 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3346
3347 if (!ret && oact) {
3348 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3349 return -EFAULT;
3350 }
3351out:
3352 return ret;
3353}
3354#ifdef CONFIG_COMPAT
3355COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3356 const struct compat_sigaction __user *, act,
3357 struct compat_sigaction __user *, oact,
3358 compat_size_t, sigsetsize)
3359{
3360 struct k_sigaction new_ka, old_ka;
3361 compat_sigset_t mask;
3362#ifdef __ARCH_HAS_SA_RESTORER
3363 compat_uptr_t restorer;
3364#endif
3365 int ret;
3366
3367 /* XXX: Don't preclude handling different sized sigset_t's. */
3368 if (sigsetsize != sizeof(compat_sigset_t))
3369 return -EINVAL;
3370
3371 if (act) {
3372 compat_uptr_t handler;
3373 ret = get_user(handler, &act->sa_handler);
3374 new_ka.sa.sa_handler = compat_ptr(handler);
3375#ifdef __ARCH_HAS_SA_RESTORER
3376 ret |= get_user(restorer, &act->sa_restorer);
3377 new_ka.sa.sa_restorer = compat_ptr(restorer);
3378#endif
3379 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3380 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3381 if (ret)
3382 return -EFAULT;
3383 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3384 }
3385
3386 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3387 if (!ret && oact) {
3388 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3389 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3390 &oact->sa_handler);
3391 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3392 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3393#ifdef __ARCH_HAS_SA_RESTORER
3394 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3395 &oact->sa_restorer);
3396#endif
3397 }
3398 return ret;
3399}
3400#endif
3401#endif /* !CONFIG_ODD_RT_SIGACTION */
3402
3403#ifdef CONFIG_OLD_SIGACTION
3404SYSCALL_DEFINE3(sigaction, int, sig,
3405 const struct old_sigaction __user *, act,
3406 struct old_sigaction __user *, oact)
3407{
3408 struct k_sigaction new_ka, old_ka;
3409 int ret;
3410
3411 if (act) {
3412 old_sigset_t mask;
3413 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3414 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3415 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3416 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3417 __get_user(mask, &act->sa_mask))
3418 return -EFAULT;
3419#ifdef __ARCH_HAS_KA_RESTORER
3420 new_ka.ka_restorer = NULL;
3421#endif
3422 siginitset(&new_ka.sa.sa_mask, mask);
3423 }
3424
3425 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3426
3427 if (!ret && oact) {
3428 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3429 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3430 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3431 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3432 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3433 return -EFAULT;
3434 }
3435
3436 return ret;
3437}
3438#endif
3439#ifdef CONFIG_COMPAT_OLD_SIGACTION
3440COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3441 const struct compat_old_sigaction __user *, act,
3442 struct compat_old_sigaction __user *, oact)
3443{
3444 struct k_sigaction new_ka, old_ka;
3445 int ret;
3446 compat_old_sigset_t mask;
3447 compat_uptr_t handler, restorer;
3448
3449 if (act) {
3450 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3451 __get_user(handler, &act->sa_handler) ||
3452 __get_user(restorer, &act->sa_restorer) ||
3453 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3454 __get_user(mask, &act->sa_mask))
3455 return -EFAULT;
3456
3457#ifdef __ARCH_HAS_KA_RESTORER
3458 new_ka.ka_restorer = NULL;
3459#endif
3460 new_ka.sa.sa_handler = compat_ptr(handler);
3461 new_ka.sa.sa_restorer = compat_ptr(restorer);
3462 siginitset(&new_ka.sa.sa_mask, mask);
3463 }
3464
3465 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3466
3467 if (!ret && oact) {
3468 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3469 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3470 &oact->sa_handler) ||
3471 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3472 &oact->sa_restorer) ||
3473 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3474 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3475 return -EFAULT;
3476 }
3477 return ret;
3478}
3479#endif
3480
3481#ifdef CONFIG_SGETMASK_SYSCALL
3482
3483/*
3484 * For backwards compatibility. Functionality superseded by sigprocmask.
3485 */
3486SYSCALL_DEFINE0(sgetmask)
3487{
3488 /* SMP safe */
3489 return current->blocked.sig[0];
3490}
3491
3492SYSCALL_DEFINE1(ssetmask, int, newmask)
3493{
3494 int old = current->blocked.sig[0];
3495 sigset_t newset;
3496
3497 siginitset(&newset, newmask);
3498 set_current_blocked(&newset);
3499
3500 return old;
3501}
3502#endif /* CONFIG_SGETMASK_SYSCALL */
3503
3504#ifdef __ARCH_WANT_SYS_SIGNAL
3505/*
3506 * For backwards compatibility. Functionality superseded by sigaction.
3507 */
3508SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3509{
3510 struct k_sigaction new_sa, old_sa;
3511 int ret;
3512
3513 new_sa.sa.sa_handler = handler;
3514 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3515 sigemptyset(&new_sa.sa.sa_mask);
3516
3517 ret = do_sigaction(sig, &new_sa, &old_sa);
3518
3519 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3520}
3521#endif /* __ARCH_WANT_SYS_SIGNAL */
3522
3523#ifdef __ARCH_WANT_SYS_PAUSE
3524
3525SYSCALL_DEFINE0(pause)
3526{
3527 while (!signal_pending(current)) {
3528 __set_current_state(TASK_INTERRUPTIBLE);
3529 schedule();
3530 }
3531 return -ERESTARTNOHAND;
3532}
3533
3534#endif
3535
3536static int sigsuspend(sigset_t *set)
3537{
3538 current->saved_sigmask = current->blocked;
3539 set_current_blocked(set);
3540
3541 while (!signal_pending(current)) {
3542 __set_current_state(TASK_INTERRUPTIBLE);
3543 schedule();
3544 }
3545 set_restore_sigmask();
3546 return -ERESTARTNOHAND;
3547}
3548
3549/**
3550 * sys_rt_sigsuspend - replace the signal mask for a value with the
3551 * @unewset value until a signal is received
3552 * @unewset: new signal mask value
3553 * @sigsetsize: size of sigset_t type
3554 */
3555SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3556{
3557 sigset_t newset;
3558
3559 /* XXX: Don't preclude handling different sized sigset_t's. */
3560 if (sigsetsize != sizeof(sigset_t))
3561 return -EINVAL;
3562
3563 if (copy_from_user(&newset, unewset, sizeof(newset)))
3564 return -EFAULT;
3565 return sigsuspend(&newset);
3566}
3567
3568#ifdef CONFIG_COMPAT
3569COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3570{
3571#ifdef __BIG_ENDIAN
3572 sigset_t newset;
3573 compat_sigset_t newset32;
3574
3575 /* XXX: Don't preclude handling different sized sigset_t's. */
3576 if (sigsetsize != sizeof(sigset_t))
3577 return -EINVAL;
3578
3579 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3580 return -EFAULT;
3581 sigset_from_compat(&newset, &newset32);
3582 return sigsuspend(&newset);
3583#else
3584 /* on little-endian bitmaps don't care about granularity */
3585 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3586#endif
3587}
3588#endif
3589
3590#ifdef CONFIG_OLD_SIGSUSPEND
3591SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3592{
3593 sigset_t blocked;
3594 siginitset(&blocked, mask);
3595 return sigsuspend(&blocked);
3596}
3597#endif
3598#ifdef CONFIG_OLD_SIGSUSPEND3
3599SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3600{
3601 sigset_t blocked;
3602 siginitset(&blocked, mask);
3603 return sigsuspend(&blocked);
3604}
3605#endif
3606
3607__weak const char *arch_vma_name(struct vm_area_struct *vma)
3608{
3609 return NULL;
3610}
3611
3612void __init signals_init(void)
3613{
3614 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3615 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3616 != offsetof(struct siginfo, _sifields._pad));
3617
3618 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3619}
3620
3621#ifdef CONFIG_KGDB_KDB
3622#include <linux/kdb.h>
3623/*
3624 * kdb_send_sig_info - Allows kdb to send signals without exposing
3625 * signal internals. This function checks if the required locks are
3626 * available before calling the main signal code, to avoid kdb
3627 * deadlocks.
3628 */
3629void
3630kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3631{
3632 static struct task_struct *kdb_prev_t;
3633 int sig, new_t;
3634 if (!spin_trylock(&t->sighand->siglock)) {
3635 kdb_printf("Can't do kill command now.\n"
3636 "The sigmask lock is held somewhere else in "
3637 "kernel, try again later\n");
3638 return;
3639 }
3640 spin_unlock(&t->sighand->siglock);
3641 new_t = kdb_prev_t != t;
3642 kdb_prev_t = t;
3643 if (t->state != TASK_RUNNING && new_t) {
3644 kdb_printf("Process is not RUNNING, sending a signal from "
3645 "kdb risks deadlock\n"
3646 "on the run queue locks. "
3647 "The signal has _not_ been sent.\n"
3648 "Reissue the kill command if you want to risk "
3649 "the deadlock.\n");
3650 return;
3651 }
3652 sig = info->si_signo;
3653 if (send_sig_info(sig, info, t))
3654 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3655 sig, t->pid);
3656 else
3657 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3658}
3659#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/proc_fs.h>
26#include <linux/tty.h>
27#include <linux/binfmts.h>
28#include <linux/coredump.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/ptrace.h>
32#include <linux/signal.h>
33#include <linux/signalfd.h>
34#include <linux/ratelimit.h>
35#include <linux/tracehook.h>
36#include <linux/capability.h>
37#include <linux/freezer.h>
38#include <linux/pid_namespace.h>
39#include <linux/nsproxy.h>
40#include <linux/user_namespace.h>
41#include <linux/uprobes.h>
42#include <linux/compat.h>
43#include <linux/cn_proc.h>
44#include <linux/compiler.h>
45#include <linux/posix-timers.h>
46#include <linux/livepatch.h>
47#include <linux/cgroup.h>
48#include <linux/audit.h>
49
50#define CREATE_TRACE_POINTS
51#include <trace/events/signal.h>
52
53#include <asm/param.h>
54#include <linux/uaccess.h>
55#include <asm/unistd.h>
56#include <asm/siginfo.h>
57#include <asm/cacheflush.h>
58
59/*
60 * SLAB caches for signal bits.
61 */
62
63static struct kmem_cache *sigqueue_cachep;
64
65int print_fatal_signals __read_mostly;
66
67static void __user *sig_handler(struct task_struct *t, int sig)
68{
69 return t->sighand->action[sig - 1].sa.sa_handler;
70}
71
72static inline bool sig_handler_ignored(void __user *handler, int sig)
73{
74 /* Is it explicitly or implicitly ignored? */
75 return handler == SIG_IGN ||
76 (handler == SIG_DFL && sig_kernel_ignore(sig));
77}
78
79static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
80{
81 void __user *handler;
82
83 handler = sig_handler(t, sig);
84
85 /* SIGKILL and SIGSTOP may not be sent to the global init */
86 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
87 return true;
88
89 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
90 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
91 return true;
92
93 /* Only allow kernel generated signals to this kthread */
94 if (unlikely((t->flags & PF_KTHREAD) &&
95 (handler == SIG_KTHREAD_KERNEL) && !force))
96 return true;
97
98 return sig_handler_ignored(handler, sig);
99}
100
101static bool sig_ignored(struct task_struct *t, int sig, bool force)
102{
103 /*
104 * Blocked signals are never ignored, since the
105 * signal handler may change by the time it is
106 * unblocked.
107 */
108 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
109 return false;
110
111 /*
112 * Tracers may want to know about even ignored signal unless it
113 * is SIGKILL which can't be reported anyway but can be ignored
114 * by SIGNAL_UNKILLABLE task.
115 */
116 if (t->ptrace && sig != SIGKILL)
117 return false;
118
119 return sig_task_ignored(t, sig, force);
120}
121
122/*
123 * Re-calculate pending state from the set of locally pending
124 * signals, globally pending signals, and blocked signals.
125 */
126static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
127{
128 unsigned long ready;
129 long i;
130
131 switch (_NSIG_WORDS) {
132 default:
133 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
134 ready |= signal->sig[i] &~ blocked->sig[i];
135 break;
136
137 case 4: ready = signal->sig[3] &~ blocked->sig[3];
138 ready |= signal->sig[2] &~ blocked->sig[2];
139 ready |= signal->sig[1] &~ blocked->sig[1];
140 ready |= signal->sig[0] &~ blocked->sig[0];
141 break;
142
143 case 2: ready = signal->sig[1] &~ blocked->sig[1];
144 ready |= signal->sig[0] &~ blocked->sig[0];
145 break;
146
147 case 1: ready = signal->sig[0] &~ blocked->sig[0];
148 }
149 return ready != 0;
150}
151
152#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
153
154static bool recalc_sigpending_tsk(struct task_struct *t)
155{
156 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
157 PENDING(&t->pending, &t->blocked) ||
158 PENDING(&t->signal->shared_pending, &t->blocked) ||
159 cgroup_task_frozen(t)) {
160 set_tsk_thread_flag(t, TIF_SIGPENDING);
161 return true;
162 }
163
164 /*
165 * We must never clear the flag in another thread, or in current
166 * when it's possible the current syscall is returning -ERESTART*.
167 * So we don't clear it here, and only callers who know they should do.
168 */
169 return false;
170}
171
172/*
173 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
174 * This is superfluous when called on current, the wakeup is a harmless no-op.
175 */
176void recalc_sigpending_and_wake(struct task_struct *t)
177{
178 if (recalc_sigpending_tsk(t))
179 signal_wake_up(t, 0);
180}
181
182void recalc_sigpending(void)
183{
184 if (!recalc_sigpending_tsk(current) && !freezing(current) &&
185 !klp_patch_pending(current))
186 clear_thread_flag(TIF_SIGPENDING);
187
188}
189EXPORT_SYMBOL(recalc_sigpending);
190
191void calculate_sigpending(void)
192{
193 /* Have any signals or users of TIF_SIGPENDING been delayed
194 * until after fork?
195 */
196 spin_lock_irq(¤t->sighand->siglock);
197 set_tsk_thread_flag(current, TIF_SIGPENDING);
198 recalc_sigpending();
199 spin_unlock_irq(¤t->sighand->siglock);
200}
201
202/* Given the mask, find the first available signal that should be serviced. */
203
204#define SYNCHRONOUS_MASK \
205 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
206 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
207
208int next_signal(struct sigpending *pending, sigset_t *mask)
209{
210 unsigned long i, *s, *m, x;
211 int sig = 0;
212
213 s = pending->signal.sig;
214 m = mask->sig;
215
216 /*
217 * Handle the first word specially: it contains the
218 * synchronous signals that need to be dequeued first.
219 */
220 x = *s &~ *m;
221 if (x) {
222 if (x & SYNCHRONOUS_MASK)
223 x &= SYNCHRONOUS_MASK;
224 sig = ffz(~x) + 1;
225 return sig;
226 }
227
228 switch (_NSIG_WORDS) {
229 default:
230 for (i = 1; i < _NSIG_WORDS; ++i) {
231 x = *++s &~ *++m;
232 if (!x)
233 continue;
234 sig = ffz(~x) + i*_NSIG_BPW + 1;
235 break;
236 }
237 break;
238
239 case 2:
240 x = s[1] &~ m[1];
241 if (!x)
242 break;
243 sig = ffz(~x) + _NSIG_BPW + 1;
244 break;
245
246 case 1:
247 /* Nothing to do */
248 break;
249 }
250
251 return sig;
252}
253
254static inline void print_dropped_signal(int sig)
255{
256 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
257
258 if (!print_fatal_signals)
259 return;
260
261 if (!__ratelimit(&ratelimit_state))
262 return;
263
264 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
265 current->comm, current->pid, sig);
266}
267
268/**
269 * task_set_jobctl_pending - set jobctl pending bits
270 * @task: target task
271 * @mask: pending bits to set
272 *
273 * Clear @mask from @task->jobctl. @mask must be subset of
274 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
275 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
276 * cleared. If @task is already being killed or exiting, this function
277 * becomes noop.
278 *
279 * CONTEXT:
280 * Must be called with @task->sighand->siglock held.
281 *
282 * RETURNS:
283 * %true if @mask is set, %false if made noop because @task was dying.
284 */
285bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
286{
287 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
288 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
289 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
290
291 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
292 return false;
293
294 if (mask & JOBCTL_STOP_SIGMASK)
295 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
296
297 task->jobctl |= mask;
298 return true;
299}
300
301/**
302 * task_clear_jobctl_trapping - clear jobctl trapping bit
303 * @task: target task
304 *
305 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
306 * Clear it and wake up the ptracer. Note that we don't need any further
307 * locking. @task->siglock guarantees that @task->parent points to the
308 * ptracer.
309 *
310 * CONTEXT:
311 * Must be called with @task->sighand->siglock held.
312 */
313void task_clear_jobctl_trapping(struct task_struct *task)
314{
315 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
316 task->jobctl &= ~JOBCTL_TRAPPING;
317 smp_mb(); /* advised by wake_up_bit() */
318 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
319 }
320}
321
322/**
323 * task_clear_jobctl_pending - clear jobctl pending bits
324 * @task: target task
325 * @mask: pending bits to clear
326 *
327 * Clear @mask from @task->jobctl. @mask must be subset of
328 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
329 * STOP bits are cleared together.
330 *
331 * If clearing of @mask leaves no stop or trap pending, this function calls
332 * task_clear_jobctl_trapping().
333 *
334 * CONTEXT:
335 * Must be called with @task->sighand->siglock held.
336 */
337void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
338{
339 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
340
341 if (mask & JOBCTL_STOP_PENDING)
342 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
343
344 task->jobctl &= ~mask;
345
346 if (!(task->jobctl & JOBCTL_PENDING_MASK))
347 task_clear_jobctl_trapping(task);
348}
349
350/**
351 * task_participate_group_stop - participate in a group stop
352 * @task: task participating in a group stop
353 *
354 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
355 * Group stop states are cleared and the group stop count is consumed if
356 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
357 * stop, the appropriate `SIGNAL_*` flags are set.
358 *
359 * CONTEXT:
360 * Must be called with @task->sighand->siglock held.
361 *
362 * RETURNS:
363 * %true if group stop completion should be notified to the parent, %false
364 * otherwise.
365 */
366static bool task_participate_group_stop(struct task_struct *task)
367{
368 struct signal_struct *sig = task->signal;
369 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
370
371 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
372
373 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
374
375 if (!consume)
376 return false;
377
378 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
379 sig->group_stop_count--;
380
381 /*
382 * Tell the caller to notify completion iff we are entering into a
383 * fresh group stop. Read comment in do_signal_stop() for details.
384 */
385 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
386 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
387 return true;
388 }
389 return false;
390}
391
392void task_join_group_stop(struct task_struct *task)
393{
394 /* Have the new thread join an on-going signal group stop */
395 unsigned long jobctl = current->jobctl;
396 if (jobctl & JOBCTL_STOP_PENDING) {
397 struct signal_struct *sig = current->signal;
398 unsigned long signr = jobctl & JOBCTL_STOP_SIGMASK;
399 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
400 if (task_set_jobctl_pending(task, signr | gstop)) {
401 sig->group_stop_count++;
402 }
403 }
404}
405
406/*
407 * allocate a new signal queue record
408 * - this may be called without locks if and only if t == current, otherwise an
409 * appropriate lock must be held to stop the target task from exiting
410 */
411static struct sigqueue *
412__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
413{
414 struct sigqueue *q = NULL;
415 struct user_struct *user;
416 int sigpending;
417
418 /*
419 * Protect access to @t credentials. This can go away when all
420 * callers hold rcu read lock.
421 *
422 * NOTE! A pending signal will hold on to the user refcount,
423 * and we get/put the refcount only when the sigpending count
424 * changes from/to zero.
425 */
426 rcu_read_lock();
427 user = __task_cred(t)->user;
428 sigpending = atomic_inc_return(&user->sigpending);
429 if (sigpending == 1)
430 get_uid(user);
431 rcu_read_unlock();
432
433 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
434 q = kmem_cache_alloc(sigqueue_cachep, flags);
435 } else {
436 print_dropped_signal(sig);
437 }
438
439 if (unlikely(q == NULL)) {
440 if (atomic_dec_and_test(&user->sigpending))
441 free_uid(user);
442 } else {
443 INIT_LIST_HEAD(&q->list);
444 q->flags = 0;
445 q->user = user;
446 }
447
448 return q;
449}
450
451static void __sigqueue_free(struct sigqueue *q)
452{
453 if (q->flags & SIGQUEUE_PREALLOC)
454 return;
455 if (atomic_dec_and_test(&q->user->sigpending))
456 free_uid(q->user);
457 kmem_cache_free(sigqueue_cachep, q);
458}
459
460void flush_sigqueue(struct sigpending *queue)
461{
462 struct sigqueue *q;
463
464 sigemptyset(&queue->signal);
465 while (!list_empty(&queue->list)) {
466 q = list_entry(queue->list.next, struct sigqueue , list);
467 list_del_init(&q->list);
468 __sigqueue_free(q);
469 }
470}
471
472/*
473 * Flush all pending signals for this kthread.
474 */
475void flush_signals(struct task_struct *t)
476{
477 unsigned long flags;
478
479 spin_lock_irqsave(&t->sighand->siglock, flags);
480 clear_tsk_thread_flag(t, TIF_SIGPENDING);
481 flush_sigqueue(&t->pending);
482 flush_sigqueue(&t->signal->shared_pending);
483 spin_unlock_irqrestore(&t->sighand->siglock, flags);
484}
485EXPORT_SYMBOL(flush_signals);
486
487#ifdef CONFIG_POSIX_TIMERS
488static void __flush_itimer_signals(struct sigpending *pending)
489{
490 sigset_t signal, retain;
491 struct sigqueue *q, *n;
492
493 signal = pending->signal;
494 sigemptyset(&retain);
495
496 list_for_each_entry_safe(q, n, &pending->list, list) {
497 int sig = q->info.si_signo;
498
499 if (likely(q->info.si_code != SI_TIMER)) {
500 sigaddset(&retain, sig);
501 } else {
502 sigdelset(&signal, sig);
503 list_del_init(&q->list);
504 __sigqueue_free(q);
505 }
506 }
507
508 sigorsets(&pending->signal, &signal, &retain);
509}
510
511void flush_itimer_signals(void)
512{
513 struct task_struct *tsk = current;
514 unsigned long flags;
515
516 spin_lock_irqsave(&tsk->sighand->siglock, flags);
517 __flush_itimer_signals(&tsk->pending);
518 __flush_itimer_signals(&tsk->signal->shared_pending);
519 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
520}
521#endif
522
523void ignore_signals(struct task_struct *t)
524{
525 int i;
526
527 for (i = 0; i < _NSIG; ++i)
528 t->sighand->action[i].sa.sa_handler = SIG_IGN;
529
530 flush_signals(t);
531}
532
533/*
534 * Flush all handlers for a task.
535 */
536
537void
538flush_signal_handlers(struct task_struct *t, int force_default)
539{
540 int i;
541 struct k_sigaction *ka = &t->sighand->action[0];
542 for (i = _NSIG ; i != 0 ; i--) {
543 if (force_default || ka->sa.sa_handler != SIG_IGN)
544 ka->sa.sa_handler = SIG_DFL;
545 ka->sa.sa_flags = 0;
546#ifdef __ARCH_HAS_SA_RESTORER
547 ka->sa.sa_restorer = NULL;
548#endif
549 sigemptyset(&ka->sa.sa_mask);
550 ka++;
551 }
552}
553
554bool unhandled_signal(struct task_struct *tsk, int sig)
555{
556 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
557 if (is_global_init(tsk))
558 return true;
559
560 if (handler != SIG_IGN && handler != SIG_DFL)
561 return false;
562
563 /* if ptraced, let the tracer determine */
564 return !tsk->ptrace;
565}
566
567static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
568 bool *resched_timer)
569{
570 struct sigqueue *q, *first = NULL;
571
572 /*
573 * Collect the siginfo appropriate to this signal. Check if
574 * there is another siginfo for the same signal.
575 */
576 list_for_each_entry(q, &list->list, list) {
577 if (q->info.si_signo == sig) {
578 if (first)
579 goto still_pending;
580 first = q;
581 }
582 }
583
584 sigdelset(&list->signal, sig);
585
586 if (first) {
587still_pending:
588 list_del_init(&first->list);
589 copy_siginfo(info, &first->info);
590
591 *resched_timer =
592 (first->flags & SIGQUEUE_PREALLOC) &&
593 (info->si_code == SI_TIMER) &&
594 (info->si_sys_private);
595
596 __sigqueue_free(first);
597 } else {
598 /*
599 * Ok, it wasn't in the queue. This must be
600 * a fast-pathed signal or we must have been
601 * out of queue space. So zero out the info.
602 */
603 clear_siginfo(info);
604 info->si_signo = sig;
605 info->si_errno = 0;
606 info->si_code = SI_USER;
607 info->si_pid = 0;
608 info->si_uid = 0;
609 }
610}
611
612static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
613 kernel_siginfo_t *info, bool *resched_timer)
614{
615 int sig = next_signal(pending, mask);
616
617 if (sig)
618 collect_signal(sig, pending, info, resched_timer);
619 return sig;
620}
621
622/*
623 * Dequeue a signal and return the element to the caller, which is
624 * expected to free it.
625 *
626 * All callers have to hold the siglock.
627 */
628int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
629{
630 bool resched_timer = false;
631 int signr;
632
633 /* We only dequeue private signals from ourselves, we don't let
634 * signalfd steal them
635 */
636 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
637 if (!signr) {
638 signr = __dequeue_signal(&tsk->signal->shared_pending,
639 mask, info, &resched_timer);
640#ifdef CONFIG_POSIX_TIMERS
641 /*
642 * itimer signal ?
643 *
644 * itimers are process shared and we restart periodic
645 * itimers in the signal delivery path to prevent DoS
646 * attacks in the high resolution timer case. This is
647 * compliant with the old way of self-restarting
648 * itimers, as the SIGALRM is a legacy signal and only
649 * queued once. Changing the restart behaviour to
650 * restart the timer in the signal dequeue path is
651 * reducing the timer noise on heavy loaded !highres
652 * systems too.
653 */
654 if (unlikely(signr == SIGALRM)) {
655 struct hrtimer *tmr = &tsk->signal->real_timer;
656
657 if (!hrtimer_is_queued(tmr) &&
658 tsk->signal->it_real_incr != 0) {
659 hrtimer_forward(tmr, tmr->base->get_time(),
660 tsk->signal->it_real_incr);
661 hrtimer_restart(tmr);
662 }
663 }
664#endif
665 }
666
667 recalc_sigpending();
668 if (!signr)
669 return 0;
670
671 if (unlikely(sig_kernel_stop(signr))) {
672 /*
673 * Set a marker that we have dequeued a stop signal. Our
674 * caller might release the siglock and then the pending
675 * stop signal it is about to process is no longer in the
676 * pending bitmasks, but must still be cleared by a SIGCONT
677 * (and overruled by a SIGKILL). So those cases clear this
678 * shared flag after we've set it. Note that this flag may
679 * remain set after the signal we return is ignored or
680 * handled. That doesn't matter because its only purpose
681 * is to alert stop-signal processing code when another
682 * processor has come along and cleared the flag.
683 */
684 current->jobctl |= JOBCTL_STOP_DEQUEUED;
685 }
686#ifdef CONFIG_POSIX_TIMERS
687 if (resched_timer) {
688 /*
689 * Release the siglock to ensure proper locking order
690 * of timer locks outside of siglocks. Note, we leave
691 * irqs disabled here, since the posix-timers code is
692 * about to disable them again anyway.
693 */
694 spin_unlock(&tsk->sighand->siglock);
695 posixtimer_rearm(info);
696 spin_lock(&tsk->sighand->siglock);
697
698 /* Don't expose the si_sys_private value to userspace */
699 info->si_sys_private = 0;
700 }
701#endif
702 return signr;
703}
704EXPORT_SYMBOL_GPL(dequeue_signal);
705
706static int dequeue_synchronous_signal(kernel_siginfo_t *info)
707{
708 struct task_struct *tsk = current;
709 struct sigpending *pending = &tsk->pending;
710 struct sigqueue *q, *sync = NULL;
711
712 /*
713 * Might a synchronous signal be in the queue?
714 */
715 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
716 return 0;
717
718 /*
719 * Return the first synchronous signal in the queue.
720 */
721 list_for_each_entry(q, &pending->list, list) {
722 /* Synchronous signals have a positive si_code */
723 if ((q->info.si_code > SI_USER) &&
724 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
725 sync = q;
726 goto next;
727 }
728 }
729 return 0;
730next:
731 /*
732 * Check if there is another siginfo for the same signal.
733 */
734 list_for_each_entry_continue(q, &pending->list, list) {
735 if (q->info.si_signo == sync->info.si_signo)
736 goto still_pending;
737 }
738
739 sigdelset(&pending->signal, sync->info.si_signo);
740 recalc_sigpending();
741still_pending:
742 list_del_init(&sync->list);
743 copy_siginfo(info, &sync->info);
744 __sigqueue_free(sync);
745 return info->si_signo;
746}
747
748/*
749 * Tell a process that it has a new active signal..
750 *
751 * NOTE! we rely on the previous spin_lock to
752 * lock interrupts for us! We can only be called with
753 * "siglock" held, and the local interrupt must
754 * have been disabled when that got acquired!
755 *
756 * No need to set need_resched since signal event passing
757 * goes through ->blocked
758 */
759void signal_wake_up_state(struct task_struct *t, unsigned int state)
760{
761 set_tsk_thread_flag(t, TIF_SIGPENDING);
762 /*
763 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
764 * case. We don't check t->state here because there is a race with it
765 * executing another processor and just now entering stopped state.
766 * By using wake_up_state, we ensure the process will wake up and
767 * handle its death signal.
768 */
769 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
770 kick_process(t);
771}
772
773/*
774 * Remove signals in mask from the pending set and queue.
775 * Returns 1 if any signals were found.
776 *
777 * All callers must be holding the siglock.
778 */
779static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
780{
781 struct sigqueue *q, *n;
782 sigset_t m;
783
784 sigandsets(&m, mask, &s->signal);
785 if (sigisemptyset(&m))
786 return;
787
788 sigandnsets(&s->signal, &s->signal, mask);
789 list_for_each_entry_safe(q, n, &s->list, list) {
790 if (sigismember(mask, q->info.si_signo)) {
791 list_del_init(&q->list);
792 __sigqueue_free(q);
793 }
794 }
795}
796
797static inline int is_si_special(const struct kernel_siginfo *info)
798{
799 return info <= SEND_SIG_PRIV;
800}
801
802static inline bool si_fromuser(const struct kernel_siginfo *info)
803{
804 return info == SEND_SIG_NOINFO ||
805 (!is_si_special(info) && SI_FROMUSER(info));
806}
807
808/*
809 * called with RCU read lock from check_kill_permission()
810 */
811static bool kill_ok_by_cred(struct task_struct *t)
812{
813 const struct cred *cred = current_cred();
814 const struct cred *tcred = __task_cred(t);
815
816 return uid_eq(cred->euid, tcred->suid) ||
817 uid_eq(cred->euid, tcred->uid) ||
818 uid_eq(cred->uid, tcred->suid) ||
819 uid_eq(cred->uid, tcred->uid) ||
820 ns_capable(tcred->user_ns, CAP_KILL);
821}
822
823/*
824 * Bad permissions for sending the signal
825 * - the caller must hold the RCU read lock
826 */
827static int check_kill_permission(int sig, struct kernel_siginfo *info,
828 struct task_struct *t)
829{
830 struct pid *sid;
831 int error;
832
833 if (!valid_signal(sig))
834 return -EINVAL;
835
836 if (!si_fromuser(info))
837 return 0;
838
839 error = audit_signal_info(sig, t); /* Let audit system see the signal */
840 if (error)
841 return error;
842
843 if (!same_thread_group(current, t) &&
844 !kill_ok_by_cred(t)) {
845 switch (sig) {
846 case SIGCONT:
847 sid = task_session(t);
848 /*
849 * We don't return the error if sid == NULL. The
850 * task was unhashed, the caller must notice this.
851 */
852 if (!sid || sid == task_session(current))
853 break;
854 fallthrough;
855 default:
856 return -EPERM;
857 }
858 }
859
860 return security_task_kill(t, info, sig, NULL);
861}
862
863/**
864 * ptrace_trap_notify - schedule trap to notify ptracer
865 * @t: tracee wanting to notify tracer
866 *
867 * This function schedules sticky ptrace trap which is cleared on the next
868 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
869 * ptracer.
870 *
871 * If @t is running, STOP trap will be taken. If trapped for STOP and
872 * ptracer is listening for events, tracee is woken up so that it can
873 * re-trap for the new event. If trapped otherwise, STOP trap will be
874 * eventually taken without returning to userland after the existing traps
875 * are finished by PTRACE_CONT.
876 *
877 * CONTEXT:
878 * Must be called with @task->sighand->siglock held.
879 */
880static void ptrace_trap_notify(struct task_struct *t)
881{
882 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
883 assert_spin_locked(&t->sighand->siglock);
884
885 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
886 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
887}
888
889/*
890 * Handle magic process-wide effects of stop/continue signals. Unlike
891 * the signal actions, these happen immediately at signal-generation
892 * time regardless of blocking, ignoring, or handling. This does the
893 * actual continuing for SIGCONT, but not the actual stopping for stop
894 * signals. The process stop is done as a signal action for SIG_DFL.
895 *
896 * Returns true if the signal should be actually delivered, otherwise
897 * it should be dropped.
898 */
899static bool prepare_signal(int sig, struct task_struct *p, bool force)
900{
901 struct signal_struct *signal = p->signal;
902 struct task_struct *t;
903 sigset_t flush;
904
905 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
906 if (!(signal->flags & SIGNAL_GROUP_EXIT))
907 return sig == SIGKILL;
908 /*
909 * The process is in the middle of dying, nothing to do.
910 */
911 } else if (sig_kernel_stop(sig)) {
912 /*
913 * This is a stop signal. Remove SIGCONT from all queues.
914 */
915 siginitset(&flush, sigmask(SIGCONT));
916 flush_sigqueue_mask(&flush, &signal->shared_pending);
917 for_each_thread(p, t)
918 flush_sigqueue_mask(&flush, &t->pending);
919 } else if (sig == SIGCONT) {
920 unsigned int why;
921 /*
922 * Remove all stop signals from all queues, wake all threads.
923 */
924 siginitset(&flush, SIG_KERNEL_STOP_MASK);
925 flush_sigqueue_mask(&flush, &signal->shared_pending);
926 for_each_thread(p, t) {
927 flush_sigqueue_mask(&flush, &t->pending);
928 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
929 if (likely(!(t->ptrace & PT_SEIZED)))
930 wake_up_state(t, __TASK_STOPPED);
931 else
932 ptrace_trap_notify(t);
933 }
934
935 /*
936 * Notify the parent with CLD_CONTINUED if we were stopped.
937 *
938 * If we were in the middle of a group stop, we pretend it
939 * was already finished, and then continued. Since SIGCHLD
940 * doesn't queue we report only CLD_STOPPED, as if the next
941 * CLD_CONTINUED was dropped.
942 */
943 why = 0;
944 if (signal->flags & SIGNAL_STOP_STOPPED)
945 why |= SIGNAL_CLD_CONTINUED;
946 else if (signal->group_stop_count)
947 why |= SIGNAL_CLD_STOPPED;
948
949 if (why) {
950 /*
951 * The first thread which returns from do_signal_stop()
952 * will take ->siglock, notice SIGNAL_CLD_MASK, and
953 * notify its parent. See get_signal().
954 */
955 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
956 signal->group_stop_count = 0;
957 signal->group_exit_code = 0;
958 }
959 }
960
961 return !sig_ignored(p, sig, force);
962}
963
964/*
965 * Test if P wants to take SIG. After we've checked all threads with this,
966 * it's equivalent to finding no threads not blocking SIG. Any threads not
967 * blocking SIG were ruled out because they are not running and already
968 * have pending signals. Such threads will dequeue from the shared queue
969 * as soon as they're available, so putting the signal on the shared queue
970 * will be equivalent to sending it to one such thread.
971 */
972static inline bool wants_signal(int sig, struct task_struct *p)
973{
974 if (sigismember(&p->blocked, sig))
975 return false;
976
977 if (p->flags & PF_EXITING)
978 return false;
979
980 if (sig == SIGKILL)
981 return true;
982
983 if (task_is_stopped_or_traced(p))
984 return false;
985
986 return task_curr(p) || !signal_pending(p);
987}
988
989static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
990{
991 struct signal_struct *signal = p->signal;
992 struct task_struct *t;
993
994 /*
995 * Now find a thread we can wake up to take the signal off the queue.
996 *
997 * If the main thread wants the signal, it gets first crack.
998 * Probably the least surprising to the average bear.
999 */
1000 if (wants_signal(sig, p))
1001 t = p;
1002 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1003 /*
1004 * There is just one thread and it does not need to be woken.
1005 * It will dequeue unblocked signals before it runs again.
1006 */
1007 return;
1008 else {
1009 /*
1010 * Otherwise try to find a suitable thread.
1011 */
1012 t = signal->curr_target;
1013 while (!wants_signal(sig, t)) {
1014 t = next_thread(t);
1015 if (t == signal->curr_target)
1016 /*
1017 * No thread needs to be woken.
1018 * Any eligible threads will see
1019 * the signal in the queue soon.
1020 */
1021 return;
1022 }
1023 signal->curr_target = t;
1024 }
1025
1026 /*
1027 * Found a killable thread. If the signal will be fatal,
1028 * then start taking the whole group down immediately.
1029 */
1030 if (sig_fatal(p, sig) &&
1031 !(signal->flags & SIGNAL_GROUP_EXIT) &&
1032 !sigismember(&t->real_blocked, sig) &&
1033 (sig == SIGKILL || !p->ptrace)) {
1034 /*
1035 * This signal will be fatal to the whole group.
1036 */
1037 if (!sig_kernel_coredump(sig)) {
1038 /*
1039 * Start a group exit and wake everybody up.
1040 * This way we don't have other threads
1041 * running and doing things after a slower
1042 * thread has the fatal signal pending.
1043 */
1044 signal->flags = SIGNAL_GROUP_EXIT;
1045 signal->group_exit_code = sig;
1046 signal->group_stop_count = 0;
1047 t = p;
1048 do {
1049 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1050 sigaddset(&t->pending.signal, SIGKILL);
1051 signal_wake_up(t, 1);
1052 } while_each_thread(p, t);
1053 return;
1054 }
1055 }
1056
1057 /*
1058 * The signal is already in the shared-pending queue.
1059 * Tell the chosen thread to wake up and dequeue it.
1060 */
1061 signal_wake_up(t, sig == SIGKILL);
1062 return;
1063}
1064
1065static inline bool legacy_queue(struct sigpending *signals, int sig)
1066{
1067 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1068}
1069
1070static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1071 enum pid_type type, bool force)
1072{
1073 struct sigpending *pending;
1074 struct sigqueue *q;
1075 int override_rlimit;
1076 int ret = 0, result;
1077
1078 assert_spin_locked(&t->sighand->siglock);
1079
1080 result = TRACE_SIGNAL_IGNORED;
1081 if (!prepare_signal(sig, t, force))
1082 goto ret;
1083
1084 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1085 /*
1086 * Short-circuit ignored signals and support queuing
1087 * exactly one non-rt signal, so that we can get more
1088 * detailed information about the cause of the signal.
1089 */
1090 result = TRACE_SIGNAL_ALREADY_PENDING;
1091 if (legacy_queue(pending, sig))
1092 goto ret;
1093
1094 result = TRACE_SIGNAL_DELIVERED;
1095 /*
1096 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1097 */
1098 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1099 goto out_set;
1100
1101 /*
1102 * Real-time signals must be queued if sent by sigqueue, or
1103 * some other real-time mechanism. It is implementation
1104 * defined whether kill() does so. We attempt to do so, on
1105 * the principle of least surprise, but since kill is not
1106 * allowed to fail with EAGAIN when low on memory we just
1107 * make sure at least one signal gets delivered and don't
1108 * pass on the info struct.
1109 */
1110 if (sig < SIGRTMIN)
1111 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1112 else
1113 override_rlimit = 0;
1114
1115 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1116 if (q) {
1117 list_add_tail(&q->list, &pending->list);
1118 switch ((unsigned long) info) {
1119 case (unsigned long) SEND_SIG_NOINFO:
1120 clear_siginfo(&q->info);
1121 q->info.si_signo = sig;
1122 q->info.si_errno = 0;
1123 q->info.si_code = SI_USER;
1124 q->info.si_pid = task_tgid_nr_ns(current,
1125 task_active_pid_ns(t));
1126 rcu_read_lock();
1127 q->info.si_uid =
1128 from_kuid_munged(task_cred_xxx(t, user_ns),
1129 current_uid());
1130 rcu_read_unlock();
1131 break;
1132 case (unsigned long) SEND_SIG_PRIV:
1133 clear_siginfo(&q->info);
1134 q->info.si_signo = sig;
1135 q->info.si_errno = 0;
1136 q->info.si_code = SI_KERNEL;
1137 q->info.si_pid = 0;
1138 q->info.si_uid = 0;
1139 break;
1140 default:
1141 copy_siginfo(&q->info, info);
1142 break;
1143 }
1144 } else if (!is_si_special(info) &&
1145 sig >= SIGRTMIN && info->si_code != SI_USER) {
1146 /*
1147 * Queue overflow, abort. We may abort if the
1148 * signal was rt and sent by user using something
1149 * other than kill().
1150 */
1151 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1152 ret = -EAGAIN;
1153 goto ret;
1154 } else {
1155 /*
1156 * This is a silent loss of information. We still
1157 * send the signal, but the *info bits are lost.
1158 */
1159 result = TRACE_SIGNAL_LOSE_INFO;
1160 }
1161
1162out_set:
1163 signalfd_notify(t, sig);
1164 sigaddset(&pending->signal, sig);
1165
1166 /* Let multiprocess signals appear after on-going forks */
1167 if (type > PIDTYPE_TGID) {
1168 struct multiprocess_signals *delayed;
1169 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1170 sigset_t *signal = &delayed->signal;
1171 /* Can't queue both a stop and a continue signal */
1172 if (sig == SIGCONT)
1173 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1174 else if (sig_kernel_stop(sig))
1175 sigdelset(signal, SIGCONT);
1176 sigaddset(signal, sig);
1177 }
1178 }
1179
1180 complete_signal(sig, t, type);
1181ret:
1182 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1183 return ret;
1184}
1185
1186static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1187{
1188 bool ret = false;
1189 switch (siginfo_layout(info->si_signo, info->si_code)) {
1190 case SIL_KILL:
1191 case SIL_CHLD:
1192 case SIL_RT:
1193 ret = true;
1194 break;
1195 case SIL_TIMER:
1196 case SIL_POLL:
1197 case SIL_FAULT:
1198 case SIL_FAULT_MCEERR:
1199 case SIL_FAULT_BNDERR:
1200 case SIL_FAULT_PKUERR:
1201 case SIL_SYS:
1202 ret = false;
1203 break;
1204 }
1205 return ret;
1206}
1207
1208static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1209 enum pid_type type)
1210{
1211 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1212 bool force = false;
1213
1214 if (info == SEND_SIG_NOINFO) {
1215 /* Force if sent from an ancestor pid namespace */
1216 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1217 } else if (info == SEND_SIG_PRIV) {
1218 /* Don't ignore kernel generated signals */
1219 force = true;
1220 } else if (has_si_pid_and_uid(info)) {
1221 /* SIGKILL and SIGSTOP is special or has ids */
1222 struct user_namespace *t_user_ns;
1223
1224 rcu_read_lock();
1225 t_user_ns = task_cred_xxx(t, user_ns);
1226 if (current_user_ns() != t_user_ns) {
1227 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1228 info->si_uid = from_kuid_munged(t_user_ns, uid);
1229 }
1230 rcu_read_unlock();
1231
1232 /* A kernel generated signal? */
1233 force = (info->si_code == SI_KERNEL);
1234
1235 /* From an ancestor pid namespace? */
1236 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1237 info->si_pid = 0;
1238 force = true;
1239 }
1240 }
1241 return __send_signal(sig, info, t, type, force);
1242}
1243
1244static void print_fatal_signal(int signr)
1245{
1246 struct pt_regs *regs = signal_pt_regs();
1247 pr_info("potentially unexpected fatal signal %d.\n", signr);
1248
1249#if defined(__i386__) && !defined(__arch_um__)
1250 pr_info("code at %08lx: ", regs->ip);
1251 {
1252 int i;
1253 for (i = 0; i < 16; i++) {
1254 unsigned char insn;
1255
1256 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1257 break;
1258 pr_cont("%02x ", insn);
1259 }
1260 }
1261 pr_cont("\n");
1262#endif
1263 preempt_disable();
1264 show_regs(regs);
1265 preempt_enable();
1266}
1267
1268static int __init setup_print_fatal_signals(char *str)
1269{
1270 get_option (&str, &print_fatal_signals);
1271
1272 return 1;
1273}
1274
1275__setup("print-fatal-signals=", setup_print_fatal_signals);
1276
1277int
1278__group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1279{
1280 return send_signal(sig, info, p, PIDTYPE_TGID);
1281}
1282
1283int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1284 enum pid_type type)
1285{
1286 unsigned long flags;
1287 int ret = -ESRCH;
1288
1289 if (lock_task_sighand(p, &flags)) {
1290 ret = send_signal(sig, info, p, type);
1291 unlock_task_sighand(p, &flags);
1292 }
1293
1294 return ret;
1295}
1296
1297/*
1298 * Force a signal that the process can't ignore: if necessary
1299 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1300 *
1301 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1302 * since we do not want to have a signal handler that was blocked
1303 * be invoked when user space had explicitly blocked it.
1304 *
1305 * We don't want to have recursive SIGSEGV's etc, for example,
1306 * that is why we also clear SIGNAL_UNKILLABLE.
1307 */
1308static int
1309force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
1310{
1311 unsigned long int flags;
1312 int ret, blocked, ignored;
1313 struct k_sigaction *action;
1314 int sig = info->si_signo;
1315
1316 spin_lock_irqsave(&t->sighand->siglock, flags);
1317 action = &t->sighand->action[sig-1];
1318 ignored = action->sa.sa_handler == SIG_IGN;
1319 blocked = sigismember(&t->blocked, sig);
1320 if (blocked || ignored) {
1321 action->sa.sa_handler = SIG_DFL;
1322 if (blocked) {
1323 sigdelset(&t->blocked, sig);
1324 recalc_sigpending_and_wake(t);
1325 }
1326 }
1327 /*
1328 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1329 * debugging to leave init killable.
1330 */
1331 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1332 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1333 ret = send_signal(sig, info, t, PIDTYPE_PID);
1334 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1335
1336 return ret;
1337}
1338
1339int force_sig_info(struct kernel_siginfo *info)
1340{
1341 return force_sig_info_to_task(info, current);
1342}
1343
1344/*
1345 * Nuke all other threads in the group.
1346 */
1347int zap_other_threads(struct task_struct *p)
1348{
1349 struct task_struct *t = p;
1350 int count = 0;
1351
1352 p->signal->group_stop_count = 0;
1353
1354 while_each_thread(p, t) {
1355 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1356 count++;
1357
1358 /* Don't bother with already dead threads */
1359 if (t->exit_state)
1360 continue;
1361 sigaddset(&t->pending.signal, SIGKILL);
1362 signal_wake_up(t, 1);
1363 }
1364
1365 return count;
1366}
1367
1368struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1369 unsigned long *flags)
1370{
1371 struct sighand_struct *sighand;
1372
1373 rcu_read_lock();
1374 for (;;) {
1375 sighand = rcu_dereference(tsk->sighand);
1376 if (unlikely(sighand == NULL))
1377 break;
1378
1379 /*
1380 * This sighand can be already freed and even reused, but
1381 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1382 * initializes ->siglock: this slab can't go away, it has
1383 * the same object type, ->siglock can't be reinitialized.
1384 *
1385 * We need to ensure that tsk->sighand is still the same
1386 * after we take the lock, we can race with de_thread() or
1387 * __exit_signal(). In the latter case the next iteration
1388 * must see ->sighand == NULL.
1389 */
1390 spin_lock_irqsave(&sighand->siglock, *flags);
1391 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1392 break;
1393 spin_unlock_irqrestore(&sighand->siglock, *flags);
1394 }
1395 rcu_read_unlock();
1396
1397 return sighand;
1398}
1399
1400/*
1401 * send signal info to all the members of a group
1402 */
1403int group_send_sig_info(int sig, struct kernel_siginfo *info,
1404 struct task_struct *p, enum pid_type type)
1405{
1406 int ret;
1407
1408 rcu_read_lock();
1409 ret = check_kill_permission(sig, info, p);
1410 rcu_read_unlock();
1411
1412 if (!ret && sig)
1413 ret = do_send_sig_info(sig, info, p, type);
1414
1415 return ret;
1416}
1417
1418/*
1419 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1420 * control characters do (^C, ^Z etc)
1421 * - the caller must hold at least a readlock on tasklist_lock
1422 */
1423int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1424{
1425 struct task_struct *p = NULL;
1426 int retval, success;
1427
1428 success = 0;
1429 retval = -ESRCH;
1430 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1431 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1432 success |= !err;
1433 retval = err;
1434 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1435 return success ? 0 : retval;
1436}
1437
1438int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1439{
1440 int error = -ESRCH;
1441 struct task_struct *p;
1442
1443 for (;;) {
1444 rcu_read_lock();
1445 p = pid_task(pid, PIDTYPE_PID);
1446 if (p)
1447 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1448 rcu_read_unlock();
1449 if (likely(!p || error != -ESRCH))
1450 return error;
1451
1452 /*
1453 * The task was unhashed in between, try again. If it
1454 * is dead, pid_task() will return NULL, if we race with
1455 * de_thread() it will find the new leader.
1456 */
1457 }
1458}
1459
1460static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1461{
1462 int error;
1463 rcu_read_lock();
1464 error = kill_pid_info(sig, info, find_vpid(pid));
1465 rcu_read_unlock();
1466 return error;
1467}
1468
1469static inline bool kill_as_cred_perm(const struct cred *cred,
1470 struct task_struct *target)
1471{
1472 const struct cred *pcred = __task_cred(target);
1473
1474 return uid_eq(cred->euid, pcred->suid) ||
1475 uid_eq(cred->euid, pcred->uid) ||
1476 uid_eq(cred->uid, pcred->suid) ||
1477 uid_eq(cred->uid, pcred->uid);
1478}
1479
1480/*
1481 * The usb asyncio usage of siginfo is wrong. The glibc support
1482 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1483 * AKA after the generic fields:
1484 * kernel_pid_t si_pid;
1485 * kernel_uid32_t si_uid;
1486 * sigval_t si_value;
1487 *
1488 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1489 * after the generic fields is:
1490 * void __user *si_addr;
1491 *
1492 * This is a practical problem when there is a 64bit big endian kernel
1493 * and a 32bit userspace. As the 32bit address will encoded in the low
1494 * 32bits of the pointer. Those low 32bits will be stored at higher
1495 * address than appear in a 32 bit pointer. So userspace will not
1496 * see the address it was expecting for it's completions.
1497 *
1498 * There is nothing in the encoding that can allow
1499 * copy_siginfo_to_user32 to detect this confusion of formats, so
1500 * handle this by requiring the caller of kill_pid_usb_asyncio to
1501 * notice when this situration takes place and to store the 32bit
1502 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1503 * parameter.
1504 */
1505int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1506 struct pid *pid, const struct cred *cred)
1507{
1508 struct kernel_siginfo info;
1509 struct task_struct *p;
1510 unsigned long flags;
1511 int ret = -EINVAL;
1512
1513 if (!valid_signal(sig))
1514 return ret;
1515
1516 clear_siginfo(&info);
1517 info.si_signo = sig;
1518 info.si_errno = errno;
1519 info.si_code = SI_ASYNCIO;
1520 *((sigval_t *)&info.si_pid) = addr;
1521
1522 rcu_read_lock();
1523 p = pid_task(pid, PIDTYPE_PID);
1524 if (!p) {
1525 ret = -ESRCH;
1526 goto out_unlock;
1527 }
1528 if (!kill_as_cred_perm(cred, p)) {
1529 ret = -EPERM;
1530 goto out_unlock;
1531 }
1532 ret = security_task_kill(p, &info, sig, cred);
1533 if (ret)
1534 goto out_unlock;
1535
1536 if (sig) {
1537 if (lock_task_sighand(p, &flags)) {
1538 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1539 unlock_task_sighand(p, &flags);
1540 } else
1541 ret = -ESRCH;
1542 }
1543out_unlock:
1544 rcu_read_unlock();
1545 return ret;
1546}
1547EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1548
1549/*
1550 * kill_something_info() interprets pid in interesting ways just like kill(2).
1551 *
1552 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1553 * is probably wrong. Should make it like BSD or SYSV.
1554 */
1555
1556static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1557{
1558 int ret;
1559
1560 if (pid > 0)
1561 return kill_proc_info(sig, info, pid);
1562
1563 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1564 if (pid == INT_MIN)
1565 return -ESRCH;
1566
1567 read_lock(&tasklist_lock);
1568 if (pid != -1) {
1569 ret = __kill_pgrp_info(sig, info,
1570 pid ? find_vpid(-pid) : task_pgrp(current));
1571 } else {
1572 int retval = 0, count = 0;
1573 struct task_struct * p;
1574
1575 for_each_process(p) {
1576 if (task_pid_vnr(p) > 1 &&
1577 !same_thread_group(p, current)) {
1578 int err = group_send_sig_info(sig, info, p,
1579 PIDTYPE_MAX);
1580 ++count;
1581 if (err != -EPERM)
1582 retval = err;
1583 }
1584 }
1585 ret = count ? retval : -ESRCH;
1586 }
1587 read_unlock(&tasklist_lock);
1588
1589 return ret;
1590}
1591
1592/*
1593 * These are for backward compatibility with the rest of the kernel source.
1594 */
1595
1596int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1597{
1598 /*
1599 * Make sure legacy kernel users don't send in bad values
1600 * (normal paths check this in check_kill_permission).
1601 */
1602 if (!valid_signal(sig))
1603 return -EINVAL;
1604
1605 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1606}
1607EXPORT_SYMBOL(send_sig_info);
1608
1609#define __si_special(priv) \
1610 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1611
1612int
1613send_sig(int sig, struct task_struct *p, int priv)
1614{
1615 return send_sig_info(sig, __si_special(priv), p);
1616}
1617EXPORT_SYMBOL(send_sig);
1618
1619void force_sig(int sig)
1620{
1621 struct kernel_siginfo info;
1622
1623 clear_siginfo(&info);
1624 info.si_signo = sig;
1625 info.si_errno = 0;
1626 info.si_code = SI_KERNEL;
1627 info.si_pid = 0;
1628 info.si_uid = 0;
1629 force_sig_info(&info);
1630}
1631EXPORT_SYMBOL(force_sig);
1632
1633/*
1634 * When things go south during signal handling, we
1635 * will force a SIGSEGV. And if the signal that caused
1636 * the problem was already a SIGSEGV, we'll want to
1637 * make sure we don't even try to deliver the signal..
1638 */
1639void force_sigsegv(int sig)
1640{
1641 struct task_struct *p = current;
1642
1643 if (sig == SIGSEGV) {
1644 unsigned long flags;
1645 spin_lock_irqsave(&p->sighand->siglock, flags);
1646 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1647 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1648 }
1649 force_sig(SIGSEGV);
1650}
1651
1652int force_sig_fault_to_task(int sig, int code, void __user *addr
1653 ___ARCH_SI_TRAPNO(int trapno)
1654 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1655 , struct task_struct *t)
1656{
1657 struct kernel_siginfo info;
1658
1659 clear_siginfo(&info);
1660 info.si_signo = sig;
1661 info.si_errno = 0;
1662 info.si_code = code;
1663 info.si_addr = addr;
1664#ifdef __ARCH_SI_TRAPNO
1665 info.si_trapno = trapno;
1666#endif
1667#ifdef __ia64__
1668 info.si_imm = imm;
1669 info.si_flags = flags;
1670 info.si_isr = isr;
1671#endif
1672 return force_sig_info_to_task(&info, t);
1673}
1674
1675int force_sig_fault(int sig, int code, void __user *addr
1676 ___ARCH_SI_TRAPNO(int trapno)
1677 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1678{
1679 return force_sig_fault_to_task(sig, code, addr
1680 ___ARCH_SI_TRAPNO(trapno)
1681 ___ARCH_SI_IA64(imm, flags, isr), current);
1682}
1683
1684int send_sig_fault(int sig, int code, void __user *addr
1685 ___ARCH_SI_TRAPNO(int trapno)
1686 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1687 , struct task_struct *t)
1688{
1689 struct kernel_siginfo info;
1690
1691 clear_siginfo(&info);
1692 info.si_signo = sig;
1693 info.si_errno = 0;
1694 info.si_code = code;
1695 info.si_addr = addr;
1696#ifdef __ARCH_SI_TRAPNO
1697 info.si_trapno = trapno;
1698#endif
1699#ifdef __ia64__
1700 info.si_imm = imm;
1701 info.si_flags = flags;
1702 info.si_isr = isr;
1703#endif
1704 return send_sig_info(info.si_signo, &info, t);
1705}
1706
1707int force_sig_mceerr(int code, void __user *addr, short lsb)
1708{
1709 struct kernel_siginfo info;
1710
1711 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1712 clear_siginfo(&info);
1713 info.si_signo = SIGBUS;
1714 info.si_errno = 0;
1715 info.si_code = code;
1716 info.si_addr = addr;
1717 info.si_addr_lsb = lsb;
1718 return force_sig_info(&info);
1719}
1720
1721int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1722{
1723 struct kernel_siginfo info;
1724
1725 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1726 clear_siginfo(&info);
1727 info.si_signo = SIGBUS;
1728 info.si_errno = 0;
1729 info.si_code = code;
1730 info.si_addr = addr;
1731 info.si_addr_lsb = lsb;
1732 return send_sig_info(info.si_signo, &info, t);
1733}
1734EXPORT_SYMBOL(send_sig_mceerr);
1735
1736int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1737{
1738 struct kernel_siginfo info;
1739
1740 clear_siginfo(&info);
1741 info.si_signo = SIGSEGV;
1742 info.si_errno = 0;
1743 info.si_code = SEGV_BNDERR;
1744 info.si_addr = addr;
1745 info.si_lower = lower;
1746 info.si_upper = upper;
1747 return force_sig_info(&info);
1748}
1749
1750#ifdef SEGV_PKUERR
1751int force_sig_pkuerr(void __user *addr, u32 pkey)
1752{
1753 struct kernel_siginfo info;
1754
1755 clear_siginfo(&info);
1756 info.si_signo = SIGSEGV;
1757 info.si_errno = 0;
1758 info.si_code = SEGV_PKUERR;
1759 info.si_addr = addr;
1760 info.si_pkey = pkey;
1761 return force_sig_info(&info);
1762}
1763#endif
1764
1765/* For the crazy architectures that include trap information in
1766 * the errno field, instead of an actual errno value.
1767 */
1768int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1769{
1770 struct kernel_siginfo info;
1771
1772 clear_siginfo(&info);
1773 info.si_signo = SIGTRAP;
1774 info.si_errno = errno;
1775 info.si_code = TRAP_HWBKPT;
1776 info.si_addr = addr;
1777 return force_sig_info(&info);
1778}
1779
1780int kill_pgrp(struct pid *pid, int sig, int priv)
1781{
1782 int ret;
1783
1784 read_lock(&tasklist_lock);
1785 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1786 read_unlock(&tasklist_lock);
1787
1788 return ret;
1789}
1790EXPORT_SYMBOL(kill_pgrp);
1791
1792int kill_pid(struct pid *pid, int sig, int priv)
1793{
1794 return kill_pid_info(sig, __si_special(priv), pid);
1795}
1796EXPORT_SYMBOL(kill_pid);
1797
1798/*
1799 * These functions support sending signals using preallocated sigqueue
1800 * structures. This is needed "because realtime applications cannot
1801 * afford to lose notifications of asynchronous events, like timer
1802 * expirations or I/O completions". In the case of POSIX Timers
1803 * we allocate the sigqueue structure from the timer_create. If this
1804 * allocation fails we are able to report the failure to the application
1805 * with an EAGAIN error.
1806 */
1807struct sigqueue *sigqueue_alloc(void)
1808{
1809 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1810
1811 if (q)
1812 q->flags |= SIGQUEUE_PREALLOC;
1813
1814 return q;
1815}
1816
1817void sigqueue_free(struct sigqueue *q)
1818{
1819 unsigned long flags;
1820 spinlock_t *lock = ¤t->sighand->siglock;
1821
1822 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1823 /*
1824 * We must hold ->siglock while testing q->list
1825 * to serialize with collect_signal() or with
1826 * __exit_signal()->flush_sigqueue().
1827 */
1828 spin_lock_irqsave(lock, flags);
1829 q->flags &= ~SIGQUEUE_PREALLOC;
1830 /*
1831 * If it is queued it will be freed when dequeued,
1832 * like the "regular" sigqueue.
1833 */
1834 if (!list_empty(&q->list))
1835 q = NULL;
1836 spin_unlock_irqrestore(lock, flags);
1837
1838 if (q)
1839 __sigqueue_free(q);
1840}
1841
1842int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1843{
1844 int sig = q->info.si_signo;
1845 struct sigpending *pending;
1846 struct task_struct *t;
1847 unsigned long flags;
1848 int ret, result;
1849
1850 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1851
1852 ret = -1;
1853 rcu_read_lock();
1854 t = pid_task(pid, type);
1855 if (!t || !likely(lock_task_sighand(t, &flags)))
1856 goto ret;
1857
1858 ret = 1; /* the signal is ignored */
1859 result = TRACE_SIGNAL_IGNORED;
1860 if (!prepare_signal(sig, t, false))
1861 goto out;
1862
1863 ret = 0;
1864 if (unlikely(!list_empty(&q->list))) {
1865 /*
1866 * If an SI_TIMER entry is already queue just increment
1867 * the overrun count.
1868 */
1869 BUG_ON(q->info.si_code != SI_TIMER);
1870 q->info.si_overrun++;
1871 result = TRACE_SIGNAL_ALREADY_PENDING;
1872 goto out;
1873 }
1874 q->info.si_overrun = 0;
1875
1876 signalfd_notify(t, sig);
1877 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1878 list_add_tail(&q->list, &pending->list);
1879 sigaddset(&pending->signal, sig);
1880 complete_signal(sig, t, type);
1881 result = TRACE_SIGNAL_DELIVERED;
1882out:
1883 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1884 unlock_task_sighand(t, &flags);
1885ret:
1886 rcu_read_unlock();
1887 return ret;
1888}
1889
1890static void do_notify_pidfd(struct task_struct *task)
1891{
1892 struct pid *pid;
1893
1894 WARN_ON(task->exit_state == 0);
1895 pid = task_pid(task);
1896 wake_up_all(&pid->wait_pidfd);
1897}
1898
1899/*
1900 * Let a parent know about the death of a child.
1901 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1902 *
1903 * Returns true if our parent ignored us and so we've switched to
1904 * self-reaping.
1905 */
1906bool do_notify_parent(struct task_struct *tsk, int sig)
1907{
1908 struct kernel_siginfo info;
1909 unsigned long flags;
1910 struct sighand_struct *psig;
1911 bool autoreap = false;
1912 u64 utime, stime;
1913
1914 BUG_ON(sig == -1);
1915
1916 /* do_notify_parent_cldstop should have been called instead. */
1917 BUG_ON(task_is_stopped_or_traced(tsk));
1918
1919 BUG_ON(!tsk->ptrace &&
1920 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1921
1922 /* Wake up all pidfd waiters */
1923 do_notify_pidfd(tsk);
1924
1925 if (sig != SIGCHLD) {
1926 /*
1927 * This is only possible if parent == real_parent.
1928 * Check if it has changed security domain.
1929 */
1930 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
1931 sig = SIGCHLD;
1932 }
1933
1934 clear_siginfo(&info);
1935 info.si_signo = sig;
1936 info.si_errno = 0;
1937 /*
1938 * We are under tasklist_lock here so our parent is tied to
1939 * us and cannot change.
1940 *
1941 * task_active_pid_ns will always return the same pid namespace
1942 * until a task passes through release_task.
1943 *
1944 * write_lock() currently calls preempt_disable() which is the
1945 * same as rcu_read_lock(), but according to Oleg, this is not
1946 * correct to rely on this
1947 */
1948 rcu_read_lock();
1949 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1950 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1951 task_uid(tsk));
1952 rcu_read_unlock();
1953
1954 task_cputime(tsk, &utime, &stime);
1955 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1956 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1957
1958 info.si_status = tsk->exit_code & 0x7f;
1959 if (tsk->exit_code & 0x80)
1960 info.si_code = CLD_DUMPED;
1961 else if (tsk->exit_code & 0x7f)
1962 info.si_code = CLD_KILLED;
1963 else {
1964 info.si_code = CLD_EXITED;
1965 info.si_status = tsk->exit_code >> 8;
1966 }
1967
1968 psig = tsk->parent->sighand;
1969 spin_lock_irqsave(&psig->siglock, flags);
1970 if (!tsk->ptrace && sig == SIGCHLD &&
1971 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1972 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1973 /*
1974 * We are exiting and our parent doesn't care. POSIX.1
1975 * defines special semantics for setting SIGCHLD to SIG_IGN
1976 * or setting the SA_NOCLDWAIT flag: we should be reaped
1977 * automatically and not left for our parent's wait4 call.
1978 * Rather than having the parent do it as a magic kind of
1979 * signal handler, we just set this to tell do_exit that we
1980 * can be cleaned up without becoming a zombie. Note that
1981 * we still call __wake_up_parent in this case, because a
1982 * blocked sys_wait4 might now return -ECHILD.
1983 *
1984 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1985 * is implementation-defined: we do (if you don't want
1986 * it, just use SIG_IGN instead).
1987 */
1988 autoreap = true;
1989 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1990 sig = 0;
1991 }
1992 /*
1993 * Send with __send_signal as si_pid and si_uid are in the
1994 * parent's namespaces.
1995 */
1996 if (valid_signal(sig) && sig)
1997 __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
1998 __wake_up_parent(tsk, tsk->parent);
1999 spin_unlock_irqrestore(&psig->siglock, flags);
2000
2001 return autoreap;
2002}
2003
2004/**
2005 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2006 * @tsk: task reporting the state change
2007 * @for_ptracer: the notification is for ptracer
2008 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2009 *
2010 * Notify @tsk's parent that the stopped/continued state has changed. If
2011 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2012 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2013 *
2014 * CONTEXT:
2015 * Must be called with tasklist_lock at least read locked.
2016 */
2017static void do_notify_parent_cldstop(struct task_struct *tsk,
2018 bool for_ptracer, int why)
2019{
2020 struct kernel_siginfo info;
2021 unsigned long flags;
2022 struct task_struct *parent;
2023 struct sighand_struct *sighand;
2024 u64 utime, stime;
2025
2026 if (for_ptracer) {
2027 parent = tsk->parent;
2028 } else {
2029 tsk = tsk->group_leader;
2030 parent = tsk->real_parent;
2031 }
2032
2033 clear_siginfo(&info);
2034 info.si_signo = SIGCHLD;
2035 info.si_errno = 0;
2036 /*
2037 * see comment in do_notify_parent() about the following 4 lines
2038 */
2039 rcu_read_lock();
2040 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2041 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2042 rcu_read_unlock();
2043
2044 task_cputime(tsk, &utime, &stime);
2045 info.si_utime = nsec_to_clock_t(utime);
2046 info.si_stime = nsec_to_clock_t(stime);
2047
2048 info.si_code = why;
2049 switch (why) {
2050 case CLD_CONTINUED:
2051 info.si_status = SIGCONT;
2052 break;
2053 case CLD_STOPPED:
2054 info.si_status = tsk->signal->group_exit_code & 0x7f;
2055 break;
2056 case CLD_TRAPPED:
2057 info.si_status = tsk->exit_code & 0x7f;
2058 break;
2059 default:
2060 BUG();
2061 }
2062
2063 sighand = parent->sighand;
2064 spin_lock_irqsave(&sighand->siglock, flags);
2065 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2066 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2067 __group_send_sig_info(SIGCHLD, &info, parent);
2068 /*
2069 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2070 */
2071 __wake_up_parent(tsk, parent);
2072 spin_unlock_irqrestore(&sighand->siglock, flags);
2073}
2074
2075static inline bool may_ptrace_stop(void)
2076{
2077 if (!likely(current->ptrace))
2078 return false;
2079 /*
2080 * Are we in the middle of do_coredump?
2081 * If so and our tracer is also part of the coredump stopping
2082 * is a deadlock situation, and pointless because our tracer
2083 * is dead so don't allow us to stop.
2084 * If SIGKILL was already sent before the caller unlocked
2085 * ->siglock we must see ->core_state != NULL. Otherwise it
2086 * is safe to enter schedule().
2087 *
2088 * This is almost outdated, a task with the pending SIGKILL can't
2089 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
2090 * after SIGKILL was already dequeued.
2091 */
2092 if (unlikely(current->mm->core_state) &&
2093 unlikely(current->mm == current->parent->mm))
2094 return false;
2095
2096 return true;
2097}
2098
2099/*
2100 * Return non-zero if there is a SIGKILL that should be waking us up.
2101 * Called with the siglock held.
2102 */
2103static bool sigkill_pending(struct task_struct *tsk)
2104{
2105 return sigismember(&tsk->pending.signal, SIGKILL) ||
2106 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
2107}
2108
2109/*
2110 * This must be called with current->sighand->siglock held.
2111 *
2112 * This should be the path for all ptrace stops.
2113 * We always set current->last_siginfo while stopped here.
2114 * That makes it a way to test a stopped process for
2115 * being ptrace-stopped vs being job-control-stopped.
2116 *
2117 * If we actually decide not to stop at all because the tracer
2118 * is gone, we keep current->exit_code unless clear_code.
2119 */
2120static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
2121 __releases(¤t->sighand->siglock)
2122 __acquires(¤t->sighand->siglock)
2123{
2124 bool gstop_done = false;
2125
2126 if (arch_ptrace_stop_needed(exit_code, info)) {
2127 /*
2128 * The arch code has something special to do before a
2129 * ptrace stop. This is allowed to block, e.g. for faults
2130 * on user stack pages. We can't keep the siglock while
2131 * calling arch_ptrace_stop, so we must release it now.
2132 * To preserve proper semantics, we must do this before
2133 * any signal bookkeeping like checking group_stop_count.
2134 * Meanwhile, a SIGKILL could come in before we retake the
2135 * siglock. That must prevent us from sleeping in TASK_TRACED.
2136 * So after regaining the lock, we must check for SIGKILL.
2137 */
2138 spin_unlock_irq(¤t->sighand->siglock);
2139 arch_ptrace_stop(exit_code, info);
2140 spin_lock_irq(¤t->sighand->siglock);
2141 if (sigkill_pending(current))
2142 return;
2143 }
2144
2145 set_special_state(TASK_TRACED);
2146
2147 /*
2148 * We're committing to trapping. TRACED should be visible before
2149 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2150 * Also, transition to TRACED and updates to ->jobctl should be
2151 * atomic with respect to siglock and should be done after the arch
2152 * hook as siglock is released and regrabbed across it.
2153 *
2154 * TRACER TRACEE
2155 *
2156 * ptrace_attach()
2157 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2158 * do_wait()
2159 * set_current_state() smp_wmb();
2160 * ptrace_do_wait()
2161 * wait_task_stopped()
2162 * task_stopped_code()
2163 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2164 */
2165 smp_wmb();
2166
2167 current->last_siginfo = info;
2168 current->exit_code = exit_code;
2169
2170 /*
2171 * If @why is CLD_STOPPED, we're trapping to participate in a group
2172 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2173 * across siglock relocks since INTERRUPT was scheduled, PENDING
2174 * could be clear now. We act as if SIGCONT is received after
2175 * TASK_TRACED is entered - ignore it.
2176 */
2177 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2178 gstop_done = task_participate_group_stop(current);
2179
2180 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2181 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2182 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2183 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2184
2185 /* entering a trap, clear TRAPPING */
2186 task_clear_jobctl_trapping(current);
2187
2188 spin_unlock_irq(¤t->sighand->siglock);
2189 read_lock(&tasklist_lock);
2190 if (may_ptrace_stop()) {
2191 /*
2192 * Notify parents of the stop.
2193 *
2194 * While ptraced, there are two parents - the ptracer and
2195 * the real_parent of the group_leader. The ptracer should
2196 * know about every stop while the real parent is only
2197 * interested in the completion of group stop. The states
2198 * for the two don't interact with each other. Notify
2199 * separately unless they're gonna be duplicates.
2200 */
2201 do_notify_parent_cldstop(current, true, why);
2202 if (gstop_done && ptrace_reparented(current))
2203 do_notify_parent_cldstop(current, false, why);
2204
2205 /*
2206 * Don't want to allow preemption here, because
2207 * sys_ptrace() needs this task to be inactive.
2208 *
2209 * XXX: implement read_unlock_no_resched().
2210 */
2211 preempt_disable();
2212 read_unlock(&tasklist_lock);
2213 cgroup_enter_frozen();
2214 preempt_enable_no_resched();
2215 freezable_schedule();
2216 cgroup_leave_frozen(true);
2217 } else {
2218 /*
2219 * By the time we got the lock, our tracer went away.
2220 * Don't drop the lock yet, another tracer may come.
2221 *
2222 * If @gstop_done, the ptracer went away between group stop
2223 * completion and here. During detach, it would have set
2224 * JOBCTL_STOP_PENDING on us and we'll re-enter
2225 * TASK_STOPPED in do_signal_stop() on return, so notifying
2226 * the real parent of the group stop completion is enough.
2227 */
2228 if (gstop_done)
2229 do_notify_parent_cldstop(current, false, why);
2230
2231 /* tasklist protects us from ptrace_freeze_traced() */
2232 __set_current_state(TASK_RUNNING);
2233 if (clear_code)
2234 current->exit_code = 0;
2235 read_unlock(&tasklist_lock);
2236 }
2237
2238 /*
2239 * We are back. Now reacquire the siglock before touching
2240 * last_siginfo, so that we are sure to have synchronized with
2241 * any signal-sending on another CPU that wants to examine it.
2242 */
2243 spin_lock_irq(¤t->sighand->siglock);
2244 current->last_siginfo = NULL;
2245
2246 /* LISTENING can be set only during STOP traps, clear it */
2247 current->jobctl &= ~JOBCTL_LISTENING;
2248
2249 /*
2250 * Queued signals ignored us while we were stopped for tracing.
2251 * So check for any that we should take before resuming user mode.
2252 * This sets TIF_SIGPENDING, but never clears it.
2253 */
2254 recalc_sigpending_tsk(current);
2255}
2256
2257static void ptrace_do_notify(int signr, int exit_code, int why)
2258{
2259 kernel_siginfo_t info;
2260
2261 clear_siginfo(&info);
2262 info.si_signo = signr;
2263 info.si_code = exit_code;
2264 info.si_pid = task_pid_vnr(current);
2265 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2266
2267 /* Let the debugger run. */
2268 ptrace_stop(exit_code, why, 1, &info);
2269}
2270
2271void ptrace_notify(int exit_code)
2272{
2273 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2274 if (unlikely(current->task_works))
2275 task_work_run();
2276
2277 spin_lock_irq(¤t->sighand->siglock);
2278 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2279 spin_unlock_irq(¤t->sighand->siglock);
2280}
2281
2282/**
2283 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2284 * @signr: signr causing group stop if initiating
2285 *
2286 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2287 * and participate in it. If already set, participate in the existing
2288 * group stop. If participated in a group stop (and thus slept), %true is
2289 * returned with siglock released.
2290 *
2291 * If ptraced, this function doesn't handle stop itself. Instead,
2292 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2293 * untouched. The caller must ensure that INTERRUPT trap handling takes
2294 * places afterwards.
2295 *
2296 * CONTEXT:
2297 * Must be called with @current->sighand->siglock held, which is released
2298 * on %true return.
2299 *
2300 * RETURNS:
2301 * %false if group stop is already cancelled or ptrace trap is scheduled.
2302 * %true if participated in group stop.
2303 */
2304static bool do_signal_stop(int signr)
2305 __releases(¤t->sighand->siglock)
2306{
2307 struct signal_struct *sig = current->signal;
2308
2309 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2310 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2311 struct task_struct *t;
2312
2313 /* signr will be recorded in task->jobctl for retries */
2314 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2315
2316 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2317 unlikely(signal_group_exit(sig)))
2318 return false;
2319 /*
2320 * There is no group stop already in progress. We must
2321 * initiate one now.
2322 *
2323 * While ptraced, a task may be resumed while group stop is
2324 * still in effect and then receive a stop signal and
2325 * initiate another group stop. This deviates from the
2326 * usual behavior as two consecutive stop signals can't
2327 * cause two group stops when !ptraced. That is why we
2328 * also check !task_is_stopped(t) below.
2329 *
2330 * The condition can be distinguished by testing whether
2331 * SIGNAL_STOP_STOPPED is already set. Don't generate
2332 * group_exit_code in such case.
2333 *
2334 * This is not necessary for SIGNAL_STOP_CONTINUED because
2335 * an intervening stop signal is required to cause two
2336 * continued events regardless of ptrace.
2337 */
2338 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2339 sig->group_exit_code = signr;
2340
2341 sig->group_stop_count = 0;
2342
2343 if (task_set_jobctl_pending(current, signr | gstop))
2344 sig->group_stop_count++;
2345
2346 t = current;
2347 while_each_thread(current, t) {
2348 /*
2349 * Setting state to TASK_STOPPED for a group
2350 * stop is always done with the siglock held,
2351 * so this check has no races.
2352 */
2353 if (!task_is_stopped(t) &&
2354 task_set_jobctl_pending(t, signr | gstop)) {
2355 sig->group_stop_count++;
2356 if (likely(!(t->ptrace & PT_SEIZED)))
2357 signal_wake_up(t, 0);
2358 else
2359 ptrace_trap_notify(t);
2360 }
2361 }
2362 }
2363
2364 if (likely(!current->ptrace)) {
2365 int notify = 0;
2366
2367 /*
2368 * If there are no other threads in the group, or if there
2369 * is a group stop in progress and we are the last to stop,
2370 * report to the parent.
2371 */
2372 if (task_participate_group_stop(current))
2373 notify = CLD_STOPPED;
2374
2375 set_special_state(TASK_STOPPED);
2376 spin_unlock_irq(¤t->sighand->siglock);
2377
2378 /*
2379 * Notify the parent of the group stop completion. Because
2380 * we're not holding either the siglock or tasklist_lock
2381 * here, ptracer may attach inbetween; however, this is for
2382 * group stop and should always be delivered to the real
2383 * parent of the group leader. The new ptracer will get
2384 * its notification when this task transitions into
2385 * TASK_TRACED.
2386 */
2387 if (notify) {
2388 read_lock(&tasklist_lock);
2389 do_notify_parent_cldstop(current, false, notify);
2390 read_unlock(&tasklist_lock);
2391 }
2392
2393 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2394 cgroup_enter_frozen();
2395 freezable_schedule();
2396 return true;
2397 } else {
2398 /*
2399 * While ptraced, group stop is handled by STOP trap.
2400 * Schedule it and let the caller deal with it.
2401 */
2402 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2403 return false;
2404 }
2405}
2406
2407/**
2408 * do_jobctl_trap - take care of ptrace jobctl traps
2409 *
2410 * When PT_SEIZED, it's used for both group stop and explicit
2411 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2412 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2413 * the stop signal; otherwise, %SIGTRAP.
2414 *
2415 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2416 * number as exit_code and no siginfo.
2417 *
2418 * CONTEXT:
2419 * Must be called with @current->sighand->siglock held, which may be
2420 * released and re-acquired before returning with intervening sleep.
2421 */
2422static void do_jobctl_trap(void)
2423{
2424 struct signal_struct *signal = current->signal;
2425 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2426
2427 if (current->ptrace & PT_SEIZED) {
2428 if (!signal->group_stop_count &&
2429 !(signal->flags & SIGNAL_STOP_STOPPED))
2430 signr = SIGTRAP;
2431 WARN_ON_ONCE(!signr);
2432 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2433 CLD_STOPPED);
2434 } else {
2435 WARN_ON_ONCE(!signr);
2436 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2437 current->exit_code = 0;
2438 }
2439}
2440
2441/**
2442 * do_freezer_trap - handle the freezer jobctl trap
2443 *
2444 * Puts the task into frozen state, if only the task is not about to quit.
2445 * In this case it drops JOBCTL_TRAP_FREEZE.
2446 *
2447 * CONTEXT:
2448 * Must be called with @current->sighand->siglock held,
2449 * which is always released before returning.
2450 */
2451static void do_freezer_trap(void)
2452 __releases(¤t->sighand->siglock)
2453{
2454 /*
2455 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2456 * let's make another loop to give it a chance to be handled.
2457 * In any case, we'll return back.
2458 */
2459 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2460 JOBCTL_TRAP_FREEZE) {
2461 spin_unlock_irq(¤t->sighand->siglock);
2462 return;
2463 }
2464
2465 /*
2466 * Now we're sure that there is no pending fatal signal and no
2467 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2468 * immediately (if there is a non-fatal signal pending), and
2469 * put the task into sleep.
2470 */
2471 __set_current_state(TASK_INTERRUPTIBLE);
2472 clear_thread_flag(TIF_SIGPENDING);
2473 spin_unlock_irq(¤t->sighand->siglock);
2474 cgroup_enter_frozen();
2475 freezable_schedule();
2476}
2477
2478static int ptrace_signal(int signr, kernel_siginfo_t *info)
2479{
2480 /*
2481 * We do not check sig_kernel_stop(signr) but set this marker
2482 * unconditionally because we do not know whether debugger will
2483 * change signr. This flag has no meaning unless we are going
2484 * to stop after return from ptrace_stop(). In this case it will
2485 * be checked in do_signal_stop(), we should only stop if it was
2486 * not cleared by SIGCONT while we were sleeping. See also the
2487 * comment in dequeue_signal().
2488 */
2489 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2490 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2491
2492 /* We're back. Did the debugger cancel the sig? */
2493 signr = current->exit_code;
2494 if (signr == 0)
2495 return signr;
2496
2497 current->exit_code = 0;
2498
2499 /*
2500 * Update the siginfo structure if the signal has
2501 * changed. If the debugger wanted something
2502 * specific in the siginfo structure then it should
2503 * have updated *info via PTRACE_SETSIGINFO.
2504 */
2505 if (signr != info->si_signo) {
2506 clear_siginfo(info);
2507 info->si_signo = signr;
2508 info->si_errno = 0;
2509 info->si_code = SI_USER;
2510 rcu_read_lock();
2511 info->si_pid = task_pid_vnr(current->parent);
2512 info->si_uid = from_kuid_munged(current_user_ns(),
2513 task_uid(current->parent));
2514 rcu_read_unlock();
2515 }
2516
2517 /* If the (new) signal is now blocked, requeue it. */
2518 if (sigismember(¤t->blocked, signr)) {
2519 send_signal(signr, info, current, PIDTYPE_PID);
2520 signr = 0;
2521 }
2522
2523 return signr;
2524}
2525
2526bool get_signal(struct ksignal *ksig)
2527{
2528 struct sighand_struct *sighand = current->sighand;
2529 struct signal_struct *signal = current->signal;
2530 int signr;
2531
2532 if (unlikely(uprobe_deny_signal()))
2533 return false;
2534
2535 /*
2536 * Do this once, we can't return to user-mode if freezing() == T.
2537 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2538 * thus do not need another check after return.
2539 */
2540 try_to_freeze();
2541
2542relock:
2543 spin_lock_irq(&sighand->siglock);
2544 /*
2545 * Make sure we can safely read ->jobctl() in task_work add. As Oleg
2546 * states:
2547 *
2548 * It pairs with mb (implied by cmpxchg) before READ_ONCE. So we
2549 * roughly have
2550 *
2551 * task_work_add: get_signal:
2552 * STORE(task->task_works, new_work); STORE(task->jobctl);
2553 * mb(); mb();
2554 * LOAD(task->jobctl); LOAD(task->task_works);
2555 *
2556 * and we can rely on STORE-MB-LOAD [ in task_work_add].
2557 */
2558 smp_store_mb(current->jobctl, current->jobctl & ~JOBCTL_TASK_WORK);
2559 if (unlikely(current->task_works)) {
2560 spin_unlock_irq(&sighand->siglock);
2561 task_work_run();
2562 goto relock;
2563 }
2564
2565 /*
2566 * Every stopped thread goes here after wakeup. Check to see if
2567 * we should notify the parent, prepare_signal(SIGCONT) encodes
2568 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2569 */
2570 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2571 int why;
2572
2573 if (signal->flags & SIGNAL_CLD_CONTINUED)
2574 why = CLD_CONTINUED;
2575 else
2576 why = CLD_STOPPED;
2577
2578 signal->flags &= ~SIGNAL_CLD_MASK;
2579
2580 spin_unlock_irq(&sighand->siglock);
2581
2582 /*
2583 * Notify the parent that we're continuing. This event is
2584 * always per-process and doesn't make whole lot of sense
2585 * for ptracers, who shouldn't consume the state via
2586 * wait(2) either, but, for backward compatibility, notify
2587 * the ptracer of the group leader too unless it's gonna be
2588 * a duplicate.
2589 */
2590 read_lock(&tasklist_lock);
2591 do_notify_parent_cldstop(current, false, why);
2592
2593 if (ptrace_reparented(current->group_leader))
2594 do_notify_parent_cldstop(current->group_leader,
2595 true, why);
2596 read_unlock(&tasklist_lock);
2597
2598 goto relock;
2599 }
2600
2601 /* Has this task already been marked for death? */
2602 if (signal_group_exit(signal)) {
2603 ksig->info.si_signo = signr = SIGKILL;
2604 sigdelset(¤t->pending.signal, SIGKILL);
2605 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2606 &sighand->action[SIGKILL - 1]);
2607 recalc_sigpending();
2608 goto fatal;
2609 }
2610
2611 for (;;) {
2612 struct k_sigaction *ka;
2613
2614 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2615 do_signal_stop(0))
2616 goto relock;
2617
2618 if (unlikely(current->jobctl &
2619 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2620 if (current->jobctl & JOBCTL_TRAP_MASK) {
2621 do_jobctl_trap();
2622 spin_unlock_irq(&sighand->siglock);
2623 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2624 do_freezer_trap();
2625
2626 goto relock;
2627 }
2628
2629 /*
2630 * If the task is leaving the frozen state, let's update
2631 * cgroup counters and reset the frozen bit.
2632 */
2633 if (unlikely(cgroup_task_frozen(current))) {
2634 spin_unlock_irq(&sighand->siglock);
2635 cgroup_leave_frozen(false);
2636 goto relock;
2637 }
2638
2639 /*
2640 * Signals generated by the execution of an instruction
2641 * need to be delivered before any other pending signals
2642 * so that the instruction pointer in the signal stack
2643 * frame points to the faulting instruction.
2644 */
2645 signr = dequeue_synchronous_signal(&ksig->info);
2646 if (!signr)
2647 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2648
2649 if (!signr)
2650 break; /* will return 0 */
2651
2652 if (unlikely(current->ptrace) && signr != SIGKILL) {
2653 signr = ptrace_signal(signr, &ksig->info);
2654 if (!signr)
2655 continue;
2656 }
2657
2658 ka = &sighand->action[signr-1];
2659
2660 /* Trace actually delivered signals. */
2661 trace_signal_deliver(signr, &ksig->info, ka);
2662
2663 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2664 continue;
2665 if (ka->sa.sa_handler != SIG_DFL) {
2666 /* Run the handler. */
2667 ksig->ka = *ka;
2668
2669 if (ka->sa.sa_flags & SA_ONESHOT)
2670 ka->sa.sa_handler = SIG_DFL;
2671
2672 break; /* will return non-zero "signr" value */
2673 }
2674
2675 /*
2676 * Now we are doing the default action for this signal.
2677 */
2678 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2679 continue;
2680
2681 /*
2682 * Global init gets no signals it doesn't want.
2683 * Container-init gets no signals it doesn't want from same
2684 * container.
2685 *
2686 * Note that if global/container-init sees a sig_kernel_only()
2687 * signal here, the signal must have been generated internally
2688 * or must have come from an ancestor namespace. In either
2689 * case, the signal cannot be dropped.
2690 */
2691 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2692 !sig_kernel_only(signr))
2693 continue;
2694
2695 if (sig_kernel_stop(signr)) {
2696 /*
2697 * The default action is to stop all threads in
2698 * the thread group. The job control signals
2699 * do nothing in an orphaned pgrp, but SIGSTOP
2700 * always works. Note that siglock needs to be
2701 * dropped during the call to is_orphaned_pgrp()
2702 * because of lock ordering with tasklist_lock.
2703 * This allows an intervening SIGCONT to be posted.
2704 * We need to check for that and bail out if necessary.
2705 */
2706 if (signr != SIGSTOP) {
2707 spin_unlock_irq(&sighand->siglock);
2708
2709 /* signals can be posted during this window */
2710
2711 if (is_current_pgrp_orphaned())
2712 goto relock;
2713
2714 spin_lock_irq(&sighand->siglock);
2715 }
2716
2717 if (likely(do_signal_stop(ksig->info.si_signo))) {
2718 /* It released the siglock. */
2719 goto relock;
2720 }
2721
2722 /*
2723 * We didn't actually stop, due to a race
2724 * with SIGCONT or something like that.
2725 */
2726 continue;
2727 }
2728
2729 fatal:
2730 spin_unlock_irq(&sighand->siglock);
2731 if (unlikely(cgroup_task_frozen(current)))
2732 cgroup_leave_frozen(true);
2733
2734 /*
2735 * Anything else is fatal, maybe with a core dump.
2736 */
2737 current->flags |= PF_SIGNALED;
2738
2739 if (sig_kernel_coredump(signr)) {
2740 if (print_fatal_signals)
2741 print_fatal_signal(ksig->info.si_signo);
2742 proc_coredump_connector(current);
2743 /*
2744 * If it was able to dump core, this kills all
2745 * other threads in the group and synchronizes with
2746 * their demise. If we lost the race with another
2747 * thread getting here, it set group_exit_code
2748 * first and our do_group_exit call below will use
2749 * that value and ignore the one we pass it.
2750 */
2751 do_coredump(&ksig->info);
2752 }
2753
2754 /*
2755 * Death signals, no core dump.
2756 */
2757 do_group_exit(ksig->info.si_signo);
2758 /* NOTREACHED */
2759 }
2760 spin_unlock_irq(&sighand->siglock);
2761
2762 ksig->sig = signr;
2763 return ksig->sig > 0;
2764}
2765
2766/**
2767 * signal_delivered -
2768 * @ksig: kernel signal struct
2769 * @stepping: nonzero if debugger single-step or block-step in use
2770 *
2771 * This function should be called when a signal has successfully been
2772 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2773 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2774 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2775 */
2776static void signal_delivered(struct ksignal *ksig, int stepping)
2777{
2778 sigset_t blocked;
2779
2780 /* A signal was successfully delivered, and the
2781 saved sigmask was stored on the signal frame,
2782 and will be restored by sigreturn. So we can
2783 simply clear the restore sigmask flag. */
2784 clear_restore_sigmask();
2785
2786 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2787 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2788 sigaddset(&blocked, ksig->sig);
2789 set_current_blocked(&blocked);
2790 tracehook_signal_handler(stepping);
2791}
2792
2793void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2794{
2795 if (failed)
2796 force_sigsegv(ksig->sig);
2797 else
2798 signal_delivered(ksig, stepping);
2799}
2800
2801/*
2802 * It could be that complete_signal() picked us to notify about the
2803 * group-wide signal. Other threads should be notified now to take
2804 * the shared signals in @which since we will not.
2805 */
2806static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2807{
2808 sigset_t retarget;
2809 struct task_struct *t;
2810
2811 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2812 if (sigisemptyset(&retarget))
2813 return;
2814
2815 t = tsk;
2816 while_each_thread(tsk, t) {
2817 if (t->flags & PF_EXITING)
2818 continue;
2819
2820 if (!has_pending_signals(&retarget, &t->blocked))
2821 continue;
2822 /* Remove the signals this thread can handle. */
2823 sigandsets(&retarget, &retarget, &t->blocked);
2824
2825 if (!signal_pending(t))
2826 signal_wake_up(t, 0);
2827
2828 if (sigisemptyset(&retarget))
2829 break;
2830 }
2831}
2832
2833void exit_signals(struct task_struct *tsk)
2834{
2835 int group_stop = 0;
2836 sigset_t unblocked;
2837
2838 /*
2839 * @tsk is about to have PF_EXITING set - lock out users which
2840 * expect stable threadgroup.
2841 */
2842 cgroup_threadgroup_change_begin(tsk);
2843
2844 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2845 tsk->flags |= PF_EXITING;
2846 cgroup_threadgroup_change_end(tsk);
2847 return;
2848 }
2849
2850 spin_lock_irq(&tsk->sighand->siglock);
2851 /*
2852 * From now this task is not visible for group-wide signals,
2853 * see wants_signal(), do_signal_stop().
2854 */
2855 tsk->flags |= PF_EXITING;
2856
2857 cgroup_threadgroup_change_end(tsk);
2858
2859 if (!signal_pending(tsk))
2860 goto out;
2861
2862 unblocked = tsk->blocked;
2863 signotset(&unblocked);
2864 retarget_shared_pending(tsk, &unblocked);
2865
2866 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2867 task_participate_group_stop(tsk))
2868 group_stop = CLD_STOPPED;
2869out:
2870 spin_unlock_irq(&tsk->sighand->siglock);
2871
2872 /*
2873 * If group stop has completed, deliver the notification. This
2874 * should always go to the real parent of the group leader.
2875 */
2876 if (unlikely(group_stop)) {
2877 read_lock(&tasklist_lock);
2878 do_notify_parent_cldstop(tsk, false, group_stop);
2879 read_unlock(&tasklist_lock);
2880 }
2881}
2882
2883/*
2884 * System call entry points.
2885 */
2886
2887/**
2888 * sys_restart_syscall - restart a system call
2889 */
2890SYSCALL_DEFINE0(restart_syscall)
2891{
2892 struct restart_block *restart = ¤t->restart_block;
2893 return restart->fn(restart);
2894}
2895
2896long do_no_restart_syscall(struct restart_block *param)
2897{
2898 return -EINTR;
2899}
2900
2901static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2902{
2903 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2904 sigset_t newblocked;
2905 /* A set of now blocked but previously unblocked signals. */
2906 sigandnsets(&newblocked, newset, ¤t->blocked);
2907 retarget_shared_pending(tsk, &newblocked);
2908 }
2909 tsk->blocked = *newset;
2910 recalc_sigpending();
2911}
2912
2913/**
2914 * set_current_blocked - change current->blocked mask
2915 * @newset: new mask
2916 *
2917 * It is wrong to change ->blocked directly, this helper should be used
2918 * to ensure the process can't miss a shared signal we are going to block.
2919 */
2920void set_current_blocked(sigset_t *newset)
2921{
2922 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2923 __set_current_blocked(newset);
2924}
2925
2926void __set_current_blocked(const sigset_t *newset)
2927{
2928 struct task_struct *tsk = current;
2929
2930 /*
2931 * In case the signal mask hasn't changed, there is nothing we need
2932 * to do. The current->blocked shouldn't be modified by other task.
2933 */
2934 if (sigequalsets(&tsk->blocked, newset))
2935 return;
2936
2937 spin_lock_irq(&tsk->sighand->siglock);
2938 __set_task_blocked(tsk, newset);
2939 spin_unlock_irq(&tsk->sighand->siglock);
2940}
2941
2942/*
2943 * This is also useful for kernel threads that want to temporarily
2944 * (or permanently) block certain signals.
2945 *
2946 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2947 * interface happily blocks "unblockable" signals like SIGKILL
2948 * and friends.
2949 */
2950int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2951{
2952 struct task_struct *tsk = current;
2953 sigset_t newset;
2954
2955 /* Lockless, only current can change ->blocked, never from irq */
2956 if (oldset)
2957 *oldset = tsk->blocked;
2958
2959 switch (how) {
2960 case SIG_BLOCK:
2961 sigorsets(&newset, &tsk->blocked, set);
2962 break;
2963 case SIG_UNBLOCK:
2964 sigandnsets(&newset, &tsk->blocked, set);
2965 break;
2966 case SIG_SETMASK:
2967 newset = *set;
2968 break;
2969 default:
2970 return -EINVAL;
2971 }
2972
2973 __set_current_blocked(&newset);
2974 return 0;
2975}
2976EXPORT_SYMBOL(sigprocmask);
2977
2978/*
2979 * The api helps set app-provided sigmasks.
2980 *
2981 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
2982 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
2983 *
2984 * Note that it does set_restore_sigmask() in advance, so it must be always
2985 * paired with restore_saved_sigmask_unless() before return from syscall.
2986 */
2987int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
2988{
2989 sigset_t kmask;
2990
2991 if (!umask)
2992 return 0;
2993 if (sigsetsize != sizeof(sigset_t))
2994 return -EINVAL;
2995 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
2996 return -EFAULT;
2997
2998 set_restore_sigmask();
2999 current->saved_sigmask = current->blocked;
3000 set_current_blocked(&kmask);
3001
3002 return 0;
3003}
3004
3005#ifdef CONFIG_COMPAT
3006int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3007 size_t sigsetsize)
3008{
3009 sigset_t kmask;
3010
3011 if (!umask)
3012 return 0;
3013 if (sigsetsize != sizeof(compat_sigset_t))
3014 return -EINVAL;
3015 if (get_compat_sigset(&kmask, umask))
3016 return -EFAULT;
3017
3018 set_restore_sigmask();
3019 current->saved_sigmask = current->blocked;
3020 set_current_blocked(&kmask);
3021
3022 return 0;
3023}
3024#endif
3025
3026/**
3027 * sys_rt_sigprocmask - change the list of currently blocked signals
3028 * @how: whether to add, remove, or set signals
3029 * @nset: stores pending signals
3030 * @oset: previous value of signal mask if non-null
3031 * @sigsetsize: size of sigset_t type
3032 */
3033SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3034 sigset_t __user *, oset, size_t, sigsetsize)
3035{
3036 sigset_t old_set, new_set;
3037 int error;
3038
3039 /* XXX: Don't preclude handling different sized sigset_t's. */
3040 if (sigsetsize != sizeof(sigset_t))
3041 return -EINVAL;
3042
3043 old_set = current->blocked;
3044
3045 if (nset) {
3046 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3047 return -EFAULT;
3048 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3049
3050 error = sigprocmask(how, &new_set, NULL);
3051 if (error)
3052 return error;
3053 }
3054
3055 if (oset) {
3056 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3057 return -EFAULT;
3058 }
3059
3060 return 0;
3061}
3062
3063#ifdef CONFIG_COMPAT
3064COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3065 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3066{
3067 sigset_t old_set = current->blocked;
3068
3069 /* XXX: Don't preclude handling different sized sigset_t's. */
3070 if (sigsetsize != sizeof(sigset_t))
3071 return -EINVAL;
3072
3073 if (nset) {
3074 sigset_t new_set;
3075 int error;
3076 if (get_compat_sigset(&new_set, nset))
3077 return -EFAULT;
3078 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3079
3080 error = sigprocmask(how, &new_set, NULL);
3081 if (error)
3082 return error;
3083 }
3084 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3085}
3086#endif
3087
3088static void do_sigpending(sigset_t *set)
3089{
3090 spin_lock_irq(¤t->sighand->siglock);
3091 sigorsets(set, ¤t->pending.signal,
3092 ¤t->signal->shared_pending.signal);
3093 spin_unlock_irq(¤t->sighand->siglock);
3094
3095 /* Outside the lock because only this thread touches it. */
3096 sigandsets(set, ¤t->blocked, set);
3097}
3098
3099/**
3100 * sys_rt_sigpending - examine a pending signal that has been raised
3101 * while blocked
3102 * @uset: stores pending signals
3103 * @sigsetsize: size of sigset_t type or larger
3104 */
3105SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3106{
3107 sigset_t set;
3108
3109 if (sigsetsize > sizeof(*uset))
3110 return -EINVAL;
3111
3112 do_sigpending(&set);
3113
3114 if (copy_to_user(uset, &set, sigsetsize))
3115 return -EFAULT;
3116
3117 return 0;
3118}
3119
3120#ifdef CONFIG_COMPAT
3121COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3122 compat_size_t, sigsetsize)
3123{
3124 sigset_t set;
3125
3126 if (sigsetsize > sizeof(*uset))
3127 return -EINVAL;
3128
3129 do_sigpending(&set);
3130
3131 return put_compat_sigset(uset, &set, sigsetsize);
3132}
3133#endif
3134
3135static const struct {
3136 unsigned char limit, layout;
3137} sig_sicodes[] = {
3138 [SIGILL] = { NSIGILL, SIL_FAULT },
3139 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3140 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3141 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3142 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3143#if defined(SIGEMT)
3144 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3145#endif
3146 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3147 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3148 [SIGSYS] = { NSIGSYS, SIL_SYS },
3149};
3150
3151static bool known_siginfo_layout(unsigned sig, int si_code)
3152{
3153 if (si_code == SI_KERNEL)
3154 return true;
3155 else if ((si_code > SI_USER)) {
3156 if (sig_specific_sicodes(sig)) {
3157 if (si_code <= sig_sicodes[sig].limit)
3158 return true;
3159 }
3160 else if (si_code <= NSIGPOLL)
3161 return true;
3162 }
3163 else if (si_code >= SI_DETHREAD)
3164 return true;
3165 else if (si_code == SI_ASYNCNL)
3166 return true;
3167 return false;
3168}
3169
3170enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3171{
3172 enum siginfo_layout layout = SIL_KILL;
3173 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3174 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3175 (si_code <= sig_sicodes[sig].limit)) {
3176 layout = sig_sicodes[sig].layout;
3177 /* Handle the exceptions */
3178 if ((sig == SIGBUS) &&
3179 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3180 layout = SIL_FAULT_MCEERR;
3181 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3182 layout = SIL_FAULT_BNDERR;
3183#ifdef SEGV_PKUERR
3184 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3185 layout = SIL_FAULT_PKUERR;
3186#endif
3187 }
3188 else if (si_code <= NSIGPOLL)
3189 layout = SIL_POLL;
3190 } else {
3191 if (si_code == SI_TIMER)
3192 layout = SIL_TIMER;
3193 else if (si_code == SI_SIGIO)
3194 layout = SIL_POLL;
3195 else if (si_code < 0)
3196 layout = SIL_RT;
3197 }
3198 return layout;
3199}
3200
3201static inline char __user *si_expansion(const siginfo_t __user *info)
3202{
3203 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3204}
3205
3206int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3207{
3208 char __user *expansion = si_expansion(to);
3209 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3210 return -EFAULT;
3211 if (clear_user(expansion, SI_EXPANSION_SIZE))
3212 return -EFAULT;
3213 return 0;
3214}
3215
3216static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3217 const siginfo_t __user *from)
3218{
3219 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3220 char __user *expansion = si_expansion(from);
3221 char buf[SI_EXPANSION_SIZE];
3222 int i;
3223 /*
3224 * An unknown si_code might need more than
3225 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3226 * extra bytes are 0. This guarantees copy_siginfo_to_user
3227 * will return this data to userspace exactly.
3228 */
3229 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3230 return -EFAULT;
3231 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3232 if (buf[i] != 0)
3233 return -E2BIG;
3234 }
3235 }
3236 return 0;
3237}
3238
3239static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3240 const siginfo_t __user *from)
3241{
3242 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3243 return -EFAULT;
3244 to->si_signo = signo;
3245 return post_copy_siginfo_from_user(to, from);
3246}
3247
3248int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3249{
3250 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3251 return -EFAULT;
3252 return post_copy_siginfo_from_user(to, from);
3253}
3254
3255#ifdef CONFIG_COMPAT
3256/**
3257 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3258 * @to: compat siginfo destination
3259 * @from: kernel siginfo source
3260 *
3261 * Note: This function does not work properly for the SIGCHLD on x32, but
3262 * fortunately it doesn't have to. The only valid callers for this function are
3263 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3264 * The latter does not care because SIGCHLD will never cause a coredump.
3265 */
3266void copy_siginfo_to_external32(struct compat_siginfo *to,
3267 const struct kernel_siginfo *from)
3268{
3269 memset(to, 0, sizeof(*to));
3270
3271 to->si_signo = from->si_signo;
3272 to->si_errno = from->si_errno;
3273 to->si_code = from->si_code;
3274 switch(siginfo_layout(from->si_signo, from->si_code)) {
3275 case SIL_KILL:
3276 to->si_pid = from->si_pid;
3277 to->si_uid = from->si_uid;
3278 break;
3279 case SIL_TIMER:
3280 to->si_tid = from->si_tid;
3281 to->si_overrun = from->si_overrun;
3282 to->si_int = from->si_int;
3283 break;
3284 case SIL_POLL:
3285 to->si_band = from->si_band;
3286 to->si_fd = from->si_fd;
3287 break;
3288 case SIL_FAULT:
3289 to->si_addr = ptr_to_compat(from->si_addr);
3290#ifdef __ARCH_SI_TRAPNO
3291 to->si_trapno = from->si_trapno;
3292#endif
3293 break;
3294 case SIL_FAULT_MCEERR:
3295 to->si_addr = ptr_to_compat(from->si_addr);
3296#ifdef __ARCH_SI_TRAPNO
3297 to->si_trapno = from->si_trapno;
3298#endif
3299 to->si_addr_lsb = from->si_addr_lsb;
3300 break;
3301 case SIL_FAULT_BNDERR:
3302 to->si_addr = ptr_to_compat(from->si_addr);
3303#ifdef __ARCH_SI_TRAPNO
3304 to->si_trapno = from->si_trapno;
3305#endif
3306 to->si_lower = ptr_to_compat(from->si_lower);
3307 to->si_upper = ptr_to_compat(from->si_upper);
3308 break;
3309 case SIL_FAULT_PKUERR:
3310 to->si_addr = ptr_to_compat(from->si_addr);
3311#ifdef __ARCH_SI_TRAPNO
3312 to->si_trapno = from->si_trapno;
3313#endif
3314 to->si_pkey = from->si_pkey;
3315 break;
3316 case SIL_CHLD:
3317 to->si_pid = from->si_pid;
3318 to->si_uid = from->si_uid;
3319 to->si_status = from->si_status;
3320 to->si_utime = from->si_utime;
3321 to->si_stime = from->si_stime;
3322 break;
3323 case SIL_RT:
3324 to->si_pid = from->si_pid;
3325 to->si_uid = from->si_uid;
3326 to->si_int = from->si_int;
3327 break;
3328 case SIL_SYS:
3329 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3330 to->si_syscall = from->si_syscall;
3331 to->si_arch = from->si_arch;
3332 break;
3333 }
3334}
3335
3336int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3337 const struct kernel_siginfo *from)
3338{
3339 struct compat_siginfo new;
3340
3341 copy_siginfo_to_external32(&new, from);
3342 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3343 return -EFAULT;
3344 return 0;
3345}
3346
3347static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3348 const struct compat_siginfo *from)
3349{
3350 clear_siginfo(to);
3351 to->si_signo = from->si_signo;
3352 to->si_errno = from->si_errno;
3353 to->si_code = from->si_code;
3354 switch(siginfo_layout(from->si_signo, from->si_code)) {
3355 case SIL_KILL:
3356 to->si_pid = from->si_pid;
3357 to->si_uid = from->si_uid;
3358 break;
3359 case SIL_TIMER:
3360 to->si_tid = from->si_tid;
3361 to->si_overrun = from->si_overrun;
3362 to->si_int = from->si_int;
3363 break;
3364 case SIL_POLL:
3365 to->si_band = from->si_band;
3366 to->si_fd = from->si_fd;
3367 break;
3368 case SIL_FAULT:
3369 to->si_addr = compat_ptr(from->si_addr);
3370#ifdef __ARCH_SI_TRAPNO
3371 to->si_trapno = from->si_trapno;
3372#endif
3373 break;
3374 case SIL_FAULT_MCEERR:
3375 to->si_addr = compat_ptr(from->si_addr);
3376#ifdef __ARCH_SI_TRAPNO
3377 to->si_trapno = from->si_trapno;
3378#endif
3379 to->si_addr_lsb = from->si_addr_lsb;
3380 break;
3381 case SIL_FAULT_BNDERR:
3382 to->si_addr = compat_ptr(from->si_addr);
3383#ifdef __ARCH_SI_TRAPNO
3384 to->si_trapno = from->si_trapno;
3385#endif
3386 to->si_lower = compat_ptr(from->si_lower);
3387 to->si_upper = compat_ptr(from->si_upper);
3388 break;
3389 case SIL_FAULT_PKUERR:
3390 to->si_addr = compat_ptr(from->si_addr);
3391#ifdef __ARCH_SI_TRAPNO
3392 to->si_trapno = from->si_trapno;
3393#endif
3394 to->si_pkey = from->si_pkey;
3395 break;
3396 case SIL_CHLD:
3397 to->si_pid = from->si_pid;
3398 to->si_uid = from->si_uid;
3399 to->si_status = from->si_status;
3400#ifdef CONFIG_X86_X32_ABI
3401 if (in_x32_syscall()) {
3402 to->si_utime = from->_sifields._sigchld_x32._utime;
3403 to->si_stime = from->_sifields._sigchld_x32._stime;
3404 } else
3405#endif
3406 {
3407 to->si_utime = from->si_utime;
3408 to->si_stime = from->si_stime;
3409 }
3410 break;
3411 case SIL_RT:
3412 to->si_pid = from->si_pid;
3413 to->si_uid = from->si_uid;
3414 to->si_int = from->si_int;
3415 break;
3416 case SIL_SYS:
3417 to->si_call_addr = compat_ptr(from->si_call_addr);
3418 to->si_syscall = from->si_syscall;
3419 to->si_arch = from->si_arch;
3420 break;
3421 }
3422 return 0;
3423}
3424
3425static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3426 const struct compat_siginfo __user *ufrom)
3427{
3428 struct compat_siginfo from;
3429
3430 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3431 return -EFAULT;
3432
3433 from.si_signo = signo;
3434 return post_copy_siginfo_from_user32(to, &from);
3435}
3436
3437int copy_siginfo_from_user32(struct kernel_siginfo *to,
3438 const struct compat_siginfo __user *ufrom)
3439{
3440 struct compat_siginfo from;
3441
3442 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3443 return -EFAULT;
3444
3445 return post_copy_siginfo_from_user32(to, &from);
3446}
3447#endif /* CONFIG_COMPAT */
3448
3449/**
3450 * do_sigtimedwait - wait for queued signals specified in @which
3451 * @which: queued signals to wait for
3452 * @info: if non-null, the signal's siginfo is returned here
3453 * @ts: upper bound on process time suspension
3454 */
3455static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3456 const struct timespec64 *ts)
3457{
3458 ktime_t *to = NULL, timeout = KTIME_MAX;
3459 struct task_struct *tsk = current;
3460 sigset_t mask = *which;
3461 int sig, ret = 0;
3462
3463 if (ts) {
3464 if (!timespec64_valid(ts))
3465 return -EINVAL;
3466 timeout = timespec64_to_ktime(*ts);
3467 to = &timeout;
3468 }
3469
3470 /*
3471 * Invert the set of allowed signals to get those we want to block.
3472 */
3473 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3474 signotset(&mask);
3475
3476 spin_lock_irq(&tsk->sighand->siglock);
3477 sig = dequeue_signal(tsk, &mask, info);
3478 if (!sig && timeout) {
3479 /*
3480 * None ready, temporarily unblock those we're interested
3481 * while we are sleeping in so that we'll be awakened when
3482 * they arrive. Unblocking is always fine, we can avoid
3483 * set_current_blocked().
3484 */
3485 tsk->real_blocked = tsk->blocked;
3486 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3487 recalc_sigpending();
3488 spin_unlock_irq(&tsk->sighand->siglock);
3489
3490 __set_current_state(TASK_INTERRUPTIBLE);
3491 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3492 HRTIMER_MODE_REL);
3493 spin_lock_irq(&tsk->sighand->siglock);
3494 __set_task_blocked(tsk, &tsk->real_blocked);
3495 sigemptyset(&tsk->real_blocked);
3496 sig = dequeue_signal(tsk, &mask, info);
3497 }
3498 spin_unlock_irq(&tsk->sighand->siglock);
3499
3500 if (sig)
3501 return sig;
3502 return ret ? -EINTR : -EAGAIN;
3503}
3504
3505/**
3506 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3507 * in @uthese
3508 * @uthese: queued signals to wait for
3509 * @uinfo: if non-null, the signal's siginfo is returned here
3510 * @uts: upper bound on process time suspension
3511 * @sigsetsize: size of sigset_t type
3512 */
3513SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3514 siginfo_t __user *, uinfo,
3515 const struct __kernel_timespec __user *, uts,
3516 size_t, sigsetsize)
3517{
3518 sigset_t these;
3519 struct timespec64 ts;
3520 kernel_siginfo_t info;
3521 int ret;
3522
3523 /* XXX: Don't preclude handling different sized sigset_t's. */
3524 if (sigsetsize != sizeof(sigset_t))
3525 return -EINVAL;
3526
3527 if (copy_from_user(&these, uthese, sizeof(these)))
3528 return -EFAULT;
3529
3530 if (uts) {
3531 if (get_timespec64(&ts, uts))
3532 return -EFAULT;
3533 }
3534
3535 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3536
3537 if (ret > 0 && uinfo) {
3538 if (copy_siginfo_to_user(uinfo, &info))
3539 ret = -EFAULT;
3540 }
3541
3542 return ret;
3543}
3544
3545#ifdef CONFIG_COMPAT_32BIT_TIME
3546SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3547 siginfo_t __user *, uinfo,
3548 const struct old_timespec32 __user *, uts,
3549 size_t, sigsetsize)
3550{
3551 sigset_t these;
3552 struct timespec64 ts;
3553 kernel_siginfo_t info;
3554 int ret;
3555
3556 if (sigsetsize != sizeof(sigset_t))
3557 return -EINVAL;
3558
3559 if (copy_from_user(&these, uthese, sizeof(these)))
3560 return -EFAULT;
3561
3562 if (uts) {
3563 if (get_old_timespec32(&ts, uts))
3564 return -EFAULT;
3565 }
3566
3567 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3568
3569 if (ret > 0 && uinfo) {
3570 if (copy_siginfo_to_user(uinfo, &info))
3571 ret = -EFAULT;
3572 }
3573
3574 return ret;
3575}
3576#endif
3577
3578#ifdef CONFIG_COMPAT
3579COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3580 struct compat_siginfo __user *, uinfo,
3581 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3582{
3583 sigset_t s;
3584 struct timespec64 t;
3585 kernel_siginfo_t info;
3586 long ret;
3587
3588 if (sigsetsize != sizeof(sigset_t))
3589 return -EINVAL;
3590
3591 if (get_compat_sigset(&s, uthese))
3592 return -EFAULT;
3593
3594 if (uts) {
3595 if (get_timespec64(&t, uts))
3596 return -EFAULT;
3597 }
3598
3599 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3600
3601 if (ret > 0 && uinfo) {
3602 if (copy_siginfo_to_user32(uinfo, &info))
3603 ret = -EFAULT;
3604 }
3605
3606 return ret;
3607}
3608
3609#ifdef CONFIG_COMPAT_32BIT_TIME
3610COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3611 struct compat_siginfo __user *, uinfo,
3612 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3613{
3614 sigset_t s;
3615 struct timespec64 t;
3616 kernel_siginfo_t info;
3617 long ret;
3618
3619 if (sigsetsize != sizeof(sigset_t))
3620 return -EINVAL;
3621
3622 if (get_compat_sigset(&s, uthese))
3623 return -EFAULT;
3624
3625 if (uts) {
3626 if (get_old_timespec32(&t, uts))
3627 return -EFAULT;
3628 }
3629
3630 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3631
3632 if (ret > 0 && uinfo) {
3633 if (copy_siginfo_to_user32(uinfo, &info))
3634 ret = -EFAULT;
3635 }
3636
3637 return ret;
3638}
3639#endif
3640#endif
3641
3642static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3643{
3644 clear_siginfo(info);
3645 info->si_signo = sig;
3646 info->si_errno = 0;
3647 info->si_code = SI_USER;
3648 info->si_pid = task_tgid_vnr(current);
3649 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3650}
3651
3652/**
3653 * sys_kill - send a signal to a process
3654 * @pid: the PID of the process
3655 * @sig: signal to be sent
3656 */
3657SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3658{
3659 struct kernel_siginfo info;
3660
3661 prepare_kill_siginfo(sig, &info);
3662
3663 return kill_something_info(sig, &info, pid);
3664}
3665
3666/*
3667 * Verify that the signaler and signalee either are in the same pid namespace
3668 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3669 * namespace.
3670 */
3671static bool access_pidfd_pidns(struct pid *pid)
3672{
3673 struct pid_namespace *active = task_active_pid_ns(current);
3674 struct pid_namespace *p = ns_of_pid(pid);
3675
3676 for (;;) {
3677 if (!p)
3678 return false;
3679 if (p == active)
3680 break;
3681 p = p->parent;
3682 }
3683
3684 return true;
3685}
3686
3687static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo, siginfo_t *info)
3688{
3689#ifdef CONFIG_COMPAT
3690 /*
3691 * Avoid hooking up compat syscalls and instead handle necessary
3692 * conversions here. Note, this is a stop-gap measure and should not be
3693 * considered a generic solution.
3694 */
3695 if (in_compat_syscall())
3696 return copy_siginfo_from_user32(
3697 kinfo, (struct compat_siginfo __user *)info);
3698#endif
3699 return copy_siginfo_from_user(kinfo, info);
3700}
3701
3702static struct pid *pidfd_to_pid(const struct file *file)
3703{
3704 struct pid *pid;
3705
3706 pid = pidfd_pid(file);
3707 if (!IS_ERR(pid))
3708 return pid;
3709
3710 return tgid_pidfd_to_pid(file);
3711}
3712
3713/**
3714 * sys_pidfd_send_signal - Signal a process through a pidfd
3715 * @pidfd: file descriptor of the process
3716 * @sig: signal to send
3717 * @info: signal info
3718 * @flags: future flags
3719 *
3720 * The syscall currently only signals via PIDTYPE_PID which covers
3721 * kill(<positive-pid>, <signal>. It does not signal threads or process
3722 * groups.
3723 * In order to extend the syscall to threads and process groups the @flags
3724 * argument should be used. In essence, the @flags argument will determine
3725 * what is signaled and not the file descriptor itself. Put in other words,
3726 * grouping is a property of the flags argument not a property of the file
3727 * descriptor.
3728 *
3729 * Return: 0 on success, negative errno on failure
3730 */
3731SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3732 siginfo_t __user *, info, unsigned int, flags)
3733{
3734 int ret;
3735 struct fd f;
3736 struct pid *pid;
3737 kernel_siginfo_t kinfo;
3738
3739 /* Enforce flags be set to 0 until we add an extension. */
3740 if (flags)
3741 return -EINVAL;
3742
3743 f = fdget(pidfd);
3744 if (!f.file)
3745 return -EBADF;
3746
3747 /* Is this a pidfd? */
3748 pid = pidfd_to_pid(f.file);
3749 if (IS_ERR(pid)) {
3750 ret = PTR_ERR(pid);
3751 goto err;
3752 }
3753
3754 ret = -EINVAL;
3755 if (!access_pidfd_pidns(pid))
3756 goto err;
3757
3758 if (info) {
3759 ret = copy_siginfo_from_user_any(&kinfo, info);
3760 if (unlikely(ret))
3761 goto err;
3762
3763 ret = -EINVAL;
3764 if (unlikely(sig != kinfo.si_signo))
3765 goto err;
3766
3767 /* Only allow sending arbitrary signals to yourself. */
3768 ret = -EPERM;
3769 if ((task_pid(current) != pid) &&
3770 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3771 goto err;
3772 } else {
3773 prepare_kill_siginfo(sig, &kinfo);
3774 }
3775
3776 ret = kill_pid_info(sig, &kinfo, pid);
3777
3778err:
3779 fdput(f);
3780 return ret;
3781}
3782
3783static int
3784do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3785{
3786 struct task_struct *p;
3787 int error = -ESRCH;
3788
3789 rcu_read_lock();
3790 p = find_task_by_vpid(pid);
3791 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3792 error = check_kill_permission(sig, info, p);
3793 /*
3794 * The null signal is a permissions and process existence
3795 * probe. No signal is actually delivered.
3796 */
3797 if (!error && sig) {
3798 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3799 /*
3800 * If lock_task_sighand() failed we pretend the task
3801 * dies after receiving the signal. The window is tiny,
3802 * and the signal is private anyway.
3803 */
3804 if (unlikely(error == -ESRCH))
3805 error = 0;
3806 }
3807 }
3808 rcu_read_unlock();
3809
3810 return error;
3811}
3812
3813static int do_tkill(pid_t tgid, pid_t pid, int sig)
3814{
3815 struct kernel_siginfo info;
3816
3817 clear_siginfo(&info);
3818 info.si_signo = sig;
3819 info.si_errno = 0;
3820 info.si_code = SI_TKILL;
3821 info.si_pid = task_tgid_vnr(current);
3822 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3823
3824 return do_send_specific(tgid, pid, sig, &info);
3825}
3826
3827/**
3828 * sys_tgkill - send signal to one specific thread
3829 * @tgid: the thread group ID of the thread
3830 * @pid: the PID of the thread
3831 * @sig: signal to be sent
3832 *
3833 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3834 * exists but it's not belonging to the target process anymore. This
3835 * method solves the problem of threads exiting and PIDs getting reused.
3836 */
3837SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3838{
3839 /* This is only valid for single tasks */
3840 if (pid <= 0 || tgid <= 0)
3841 return -EINVAL;
3842
3843 return do_tkill(tgid, pid, sig);
3844}
3845
3846/**
3847 * sys_tkill - send signal to one specific task
3848 * @pid: the PID of the task
3849 * @sig: signal to be sent
3850 *
3851 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3852 */
3853SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3854{
3855 /* This is only valid for single tasks */
3856 if (pid <= 0)
3857 return -EINVAL;
3858
3859 return do_tkill(0, pid, sig);
3860}
3861
3862static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3863{
3864 /* Not even root can pretend to send signals from the kernel.
3865 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3866 */
3867 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3868 (task_pid_vnr(current) != pid))
3869 return -EPERM;
3870
3871 /* POSIX.1b doesn't mention process groups. */
3872 return kill_proc_info(sig, info, pid);
3873}
3874
3875/**
3876 * sys_rt_sigqueueinfo - send signal information to a signal
3877 * @pid: the PID of the thread
3878 * @sig: signal to be sent
3879 * @uinfo: signal info to be sent
3880 */
3881SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3882 siginfo_t __user *, uinfo)
3883{
3884 kernel_siginfo_t info;
3885 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3886 if (unlikely(ret))
3887 return ret;
3888 return do_rt_sigqueueinfo(pid, sig, &info);
3889}
3890
3891#ifdef CONFIG_COMPAT
3892COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3893 compat_pid_t, pid,
3894 int, sig,
3895 struct compat_siginfo __user *, uinfo)
3896{
3897 kernel_siginfo_t info;
3898 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3899 if (unlikely(ret))
3900 return ret;
3901 return do_rt_sigqueueinfo(pid, sig, &info);
3902}
3903#endif
3904
3905static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
3906{
3907 /* This is only valid for single tasks */
3908 if (pid <= 0 || tgid <= 0)
3909 return -EINVAL;
3910
3911 /* Not even root can pretend to send signals from the kernel.
3912 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3913 */
3914 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3915 (task_pid_vnr(current) != pid))
3916 return -EPERM;
3917
3918 return do_send_specific(tgid, pid, sig, info);
3919}
3920
3921SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3922 siginfo_t __user *, uinfo)
3923{
3924 kernel_siginfo_t info;
3925 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3926 if (unlikely(ret))
3927 return ret;
3928 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3929}
3930
3931#ifdef CONFIG_COMPAT
3932COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3933 compat_pid_t, tgid,
3934 compat_pid_t, pid,
3935 int, sig,
3936 struct compat_siginfo __user *, uinfo)
3937{
3938 kernel_siginfo_t info;
3939 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3940 if (unlikely(ret))
3941 return ret;
3942 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3943}
3944#endif
3945
3946/*
3947 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3948 */
3949void kernel_sigaction(int sig, __sighandler_t action)
3950{
3951 spin_lock_irq(¤t->sighand->siglock);
3952 current->sighand->action[sig - 1].sa.sa_handler = action;
3953 if (action == SIG_IGN) {
3954 sigset_t mask;
3955
3956 sigemptyset(&mask);
3957 sigaddset(&mask, sig);
3958
3959 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3960 flush_sigqueue_mask(&mask, ¤t->pending);
3961 recalc_sigpending();
3962 }
3963 spin_unlock_irq(¤t->sighand->siglock);
3964}
3965EXPORT_SYMBOL(kernel_sigaction);
3966
3967void __weak sigaction_compat_abi(struct k_sigaction *act,
3968 struct k_sigaction *oact)
3969{
3970}
3971
3972int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3973{
3974 struct task_struct *p = current, *t;
3975 struct k_sigaction *k;
3976 sigset_t mask;
3977
3978 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3979 return -EINVAL;
3980
3981 k = &p->sighand->action[sig-1];
3982
3983 spin_lock_irq(&p->sighand->siglock);
3984 if (oact)
3985 *oact = *k;
3986
3987 sigaction_compat_abi(act, oact);
3988
3989 if (act) {
3990 sigdelsetmask(&act->sa.sa_mask,
3991 sigmask(SIGKILL) | sigmask(SIGSTOP));
3992 *k = *act;
3993 /*
3994 * POSIX 3.3.1.3:
3995 * "Setting a signal action to SIG_IGN for a signal that is
3996 * pending shall cause the pending signal to be discarded,
3997 * whether or not it is blocked."
3998 *
3999 * "Setting a signal action to SIG_DFL for a signal that is
4000 * pending and whose default action is to ignore the signal
4001 * (for example, SIGCHLD), shall cause the pending signal to
4002 * be discarded, whether or not it is blocked"
4003 */
4004 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4005 sigemptyset(&mask);
4006 sigaddset(&mask, sig);
4007 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4008 for_each_thread(p, t)
4009 flush_sigqueue_mask(&mask, &t->pending);
4010 }
4011 }
4012
4013 spin_unlock_irq(&p->sighand->siglock);
4014 return 0;
4015}
4016
4017static int
4018do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4019 size_t min_ss_size)
4020{
4021 struct task_struct *t = current;
4022
4023 if (oss) {
4024 memset(oss, 0, sizeof(stack_t));
4025 oss->ss_sp = (void __user *) t->sas_ss_sp;
4026 oss->ss_size = t->sas_ss_size;
4027 oss->ss_flags = sas_ss_flags(sp) |
4028 (current->sas_ss_flags & SS_FLAG_BITS);
4029 }
4030
4031 if (ss) {
4032 void __user *ss_sp = ss->ss_sp;
4033 size_t ss_size = ss->ss_size;
4034 unsigned ss_flags = ss->ss_flags;
4035 int ss_mode;
4036
4037 if (unlikely(on_sig_stack(sp)))
4038 return -EPERM;
4039
4040 ss_mode = ss_flags & ~SS_FLAG_BITS;
4041 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4042 ss_mode != 0))
4043 return -EINVAL;
4044
4045 if (ss_mode == SS_DISABLE) {
4046 ss_size = 0;
4047 ss_sp = NULL;
4048 } else {
4049 if (unlikely(ss_size < min_ss_size))
4050 return -ENOMEM;
4051 }
4052
4053 t->sas_ss_sp = (unsigned long) ss_sp;
4054 t->sas_ss_size = ss_size;
4055 t->sas_ss_flags = ss_flags;
4056 }
4057 return 0;
4058}
4059
4060SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4061{
4062 stack_t new, old;
4063 int err;
4064 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4065 return -EFAULT;
4066 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4067 current_user_stack_pointer(),
4068 MINSIGSTKSZ);
4069 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4070 err = -EFAULT;
4071 return err;
4072}
4073
4074int restore_altstack(const stack_t __user *uss)
4075{
4076 stack_t new;
4077 if (copy_from_user(&new, uss, sizeof(stack_t)))
4078 return -EFAULT;
4079 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4080 MINSIGSTKSZ);
4081 /* squash all but EFAULT for now */
4082 return 0;
4083}
4084
4085int __save_altstack(stack_t __user *uss, unsigned long sp)
4086{
4087 struct task_struct *t = current;
4088 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4089 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4090 __put_user(t->sas_ss_size, &uss->ss_size);
4091 if (err)
4092 return err;
4093 if (t->sas_ss_flags & SS_AUTODISARM)
4094 sas_ss_reset(t);
4095 return 0;
4096}
4097
4098#ifdef CONFIG_COMPAT
4099static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4100 compat_stack_t __user *uoss_ptr)
4101{
4102 stack_t uss, uoss;
4103 int ret;
4104
4105 if (uss_ptr) {
4106 compat_stack_t uss32;
4107 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4108 return -EFAULT;
4109 uss.ss_sp = compat_ptr(uss32.ss_sp);
4110 uss.ss_flags = uss32.ss_flags;
4111 uss.ss_size = uss32.ss_size;
4112 }
4113 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4114 compat_user_stack_pointer(),
4115 COMPAT_MINSIGSTKSZ);
4116 if (ret >= 0 && uoss_ptr) {
4117 compat_stack_t old;
4118 memset(&old, 0, sizeof(old));
4119 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4120 old.ss_flags = uoss.ss_flags;
4121 old.ss_size = uoss.ss_size;
4122 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4123 ret = -EFAULT;
4124 }
4125 return ret;
4126}
4127
4128COMPAT_SYSCALL_DEFINE2(sigaltstack,
4129 const compat_stack_t __user *, uss_ptr,
4130 compat_stack_t __user *, uoss_ptr)
4131{
4132 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4133}
4134
4135int compat_restore_altstack(const compat_stack_t __user *uss)
4136{
4137 int err = do_compat_sigaltstack(uss, NULL);
4138 /* squash all but -EFAULT for now */
4139 return err == -EFAULT ? err : 0;
4140}
4141
4142int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4143{
4144 int err;
4145 struct task_struct *t = current;
4146 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4147 &uss->ss_sp) |
4148 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4149 __put_user(t->sas_ss_size, &uss->ss_size);
4150 if (err)
4151 return err;
4152 if (t->sas_ss_flags & SS_AUTODISARM)
4153 sas_ss_reset(t);
4154 return 0;
4155}
4156#endif
4157
4158#ifdef __ARCH_WANT_SYS_SIGPENDING
4159
4160/**
4161 * sys_sigpending - examine pending signals
4162 * @uset: where mask of pending signal is returned
4163 */
4164SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4165{
4166 sigset_t set;
4167
4168 if (sizeof(old_sigset_t) > sizeof(*uset))
4169 return -EINVAL;
4170
4171 do_sigpending(&set);
4172
4173 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4174 return -EFAULT;
4175
4176 return 0;
4177}
4178
4179#ifdef CONFIG_COMPAT
4180COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4181{
4182 sigset_t set;
4183
4184 do_sigpending(&set);
4185
4186 return put_user(set.sig[0], set32);
4187}
4188#endif
4189
4190#endif
4191
4192#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4193/**
4194 * sys_sigprocmask - examine and change blocked signals
4195 * @how: whether to add, remove, or set signals
4196 * @nset: signals to add or remove (if non-null)
4197 * @oset: previous value of signal mask if non-null
4198 *
4199 * Some platforms have their own version with special arguments;
4200 * others support only sys_rt_sigprocmask.
4201 */
4202
4203SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4204 old_sigset_t __user *, oset)
4205{
4206 old_sigset_t old_set, new_set;
4207 sigset_t new_blocked;
4208
4209 old_set = current->blocked.sig[0];
4210
4211 if (nset) {
4212 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4213 return -EFAULT;
4214
4215 new_blocked = current->blocked;
4216
4217 switch (how) {
4218 case SIG_BLOCK:
4219 sigaddsetmask(&new_blocked, new_set);
4220 break;
4221 case SIG_UNBLOCK:
4222 sigdelsetmask(&new_blocked, new_set);
4223 break;
4224 case SIG_SETMASK:
4225 new_blocked.sig[0] = new_set;
4226 break;
4227 default:
4228 return -EINVAL;
4229 }
4230
4231 set_current_blocked(&new_blocked);
4232 }
4233
4234 if (oset) {
4235 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4236 return -EFAULT;
4237 }
4238
4239 return 0;
4240}
4241#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4242
4243#ifndef CONFIG_ODD_RT_SIGACTION
4244/**
4245 * sys_rt_sigaction - alter an action taken by a process
4246 * @sig: signal to be sent
4247 * @act: new sigaction
4248 * @oact: used to save the previous sigaction
4249 * @sigsetsize: size of sigset_t type
4250 */
4251SYSCALL_DEFINE4(rt_sigaction, int, sig,
4252 const struct sigaction __user *, act,
4253 struct sigaction __user *, oact,
4254 size_t, sigsetsize)
4255{
4256 struct k_sigaction new_sa, old_sa;
4257 int ret;
4258
4259 /* XXX: Don't preclude handling different sized sigset_t's. */
4260 if (sigsetsize != sizeof(sigset_t))
4261 return -EINVAL;
4262
4263 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4264 return -EFAULT;
4265
4266 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4267 if (ret)
4268 return ret;
4269
4270 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4271 return -EFAULT;
4272
4273 return 0;
4274}
4275#ifdef CONFIG_COMPAT
4276COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4277 const struct compat_sigaction __user *, act,
4278 struct compat_sigaction __user *, oact,
4279 compat_size_t, sigsetsize)
4280{
4281 struct k_sigaction new_ka, old_ka;
4282#ifdef __ARCH_HAS_SA_RESTORER
4283 compat_uptr_t restorer;
4284#endif
4285 int ret;
4286
4287 /* XXX: Don't preclude handling different sized sigset_t's. */
4288 if (sigsetsize != sizeof(compat_sigset_t))
4289 return -EINVAL;
4290
4291 if (act) {
4292 compat_uptr_t handler;
4293 ret = get_user(handler, &act->sa_handler);
4294 new_ka.sa.sa_handler = compat_ptr(handler);
4295#ifdef __ARCH_HAS_SA_RESTORER
4296 ret |= get_user(restorer, &act->sa_restorer);
4297 new_ka.sa.sa_restorer = compat_ptr(restorer);
4298#endif
4299 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4300 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4301 if (ret)
4302 return -EFAULT;
4303 }
4304
4305 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4306 if (!ret && oact) {
4307 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4308 &oact->sa_handler);
4309 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4310 sizeof(oact->sa_mask));
4311 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4312#ifdef __ARCH_HAS_SA_RESTORER
4313 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4314 &oact->sa_restorer);
4315#endif
4316 }
4317 return ret;
4318}
4319#endif
4320#endif /* !CONFIG_ODD_RT_SIGACTION */
4321
4322#ifdef CONFIG_OLD_SIGACTION
4323SYSCALL_DEFINE3(sigaction, int, sig,
4324 const struct old_sigaction __user *, act,
4325 struct old_sigaction __user *, oact)
4326{
4327 struct k_sigaction new_ka, old_ka;
4328 int ret;
4329
4330 if (act) {
4331 old_sigset_t mask;
4332 if (!access_ok(act, sizeof(*act)) ||
4333 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4334 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4335 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4336 __get_user(mask, &act->sa_mask))
4337 return -EFAULT;
4338#ifdef __ARCH_HAS_KA_RESTORER
4339 new_ka.ka_restorer = NULL;
4340#endif
4341 siginitset(&new_ka.sa.sa_mask, mask);
4342 }
4343
4344 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4345
4346 if (!ret && oact) {
4347 if (!access_ok(oact, sizeof(*oact)) ||
4348 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4349 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4350 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4351 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4352 return -EFAULT;
4353 }
4354
4355 return ret;
4356}
4357#endif
4358#ifdef CONFIG_COMPAT_OLD_SIGACTION
4359COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4360 const struct compat_old_sigaction __user *, act,
4361 struct compat_old_sigaction __user *, oact)
4362{
4363 struct k_sigaction new_ka, old_ka;
4364 int ret;
4365 compat_old_sigset_t mask;
4366 compat_uptr_t handler, restorer;
4367
4368 if (act) {
4369 if (!access_ok(act, sizeof(*act)) ||
4370 __get_user(handler, &act->sa_handler) ||
4371 __get_user(restorer, &act->sa_restorer) ||
4372 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4373 __get_user(mask, &act->sa_mask))
4374 return -EFAULT;
4375
4376#ifdef __ARCH_HAS_KA_RESTORER
4377 new_ka.ka_restorer = NULL;
4378#endif
4379 new_ka.sa.sa_handler = compat_ptr(handler);
4380 new_ka.sa.sa_restorer = compat_ptr(restorer);
4381 siginitset(&new_ka.sa.sa_mask, mask);
4382 }
4383
4384 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4385
4386 if (!ret && oact) {
4387 if (!access_ok(oact, sizeof(*oact)) ||
4388 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4389 &oact->sa_handler) ||
4390 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4391 &oact->sa_restorer) ||
4392 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4393 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4394 return -EFAULT;
4395 }
4396 return ret;
4397}
4398#endif
4399
4400#ifdef CONFIG_SGETMASK_SYSCALL
4401
4402/*
4403 * For backwards compatibility. Functionality superseded by sigprocmask.
4404 */
4405SYSCALL_DEFINE0(sgetmask)
4406{
4407 /* SMP safe */
4408 return current->blocked.sig[0];
4409}
4410
4411SYSCALL_DEFINE1(ssetmask, int, newmask)
4412{
4413 int old = current->blocked.sig[0];
4414 sigset_t newset;
4415
4416 siginitset(&newset, newmask);
4417 set_current_blocked(&newset);
4418
4419 return old;
4420}
4421#endif /* CONFIG_SGETMASK_SYSCALL */
4422
4423#ifdef __ARCH_WANT_SYS_SIGNAL
4424/*
4425 * For backwards compatibility. Functionality superseded by sigaction.
4426 */
4427SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4428{
4429 struct k_sigaction new_sa, old_sa;
4430 int ret;
4431
4432 new_sa.sa.sa_handler = handler;
4433 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4434 sigemptyset(&new_sa.sa.sa_mask);
4435
4436 ret = do_sigaction(sig, &new_sa, &old_sa);
4437
4438 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4439}
4440#endif /* __ARCH_WANT_SYS_SIGNAL */
4441
4442#ifdef __ARCH_WANT_SYS_PAUSE
4443
4444SYSCALL_DEFINE0(pause)
4445{
4446 while (!signal_pending(current)) {
4447 __set_current_state(TASK_INTERRUPTIBLE);
4448 schedule();
4449 }
4450 return -ERESTARTNOHAND;
4451}
4452
4453#endif
4454
4455static int sigsuspend(sigset_t *set)
4456{
4457 current->saved_sigmask = current->blocked;
4458 set_current_blocked(set);
4459
4460 while (!signal_pending(current)) {
4461 __set_current_state(TASK_INTERRUPTIBLE);
4462 schedule();
4463 }
4464 set_restore_sigmask();
4465 return -ERESTARTNOHAND;
4466}
4467
4468/**
4469 * sys_rt_sigsuspend - replace the signal mask for a value with the
4470 * @unewset value until a signal is received
4471 * @unewset: new signal mask value
4472 * @sigsetsize: size of sigset_t type
4473 */
4474SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4475{
4476 sigset_t newset;
4477
4478 /* XXX: Don't preclude handling different sized sigset_t's. */
4479 if (sigsetsize != sizeof(sigset_t))
4480 return -EINVAL;
4481
4482 if (copy_from_user(&newset, unewset, sizeof(newset)))
4483 return -EFAULT;
4484 return sigsuspend(&newset);
4485}
4486
4487#ifdef CONFIG_COMPAT
4488COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4489{
4490 sigset_t newset;
4491
4492 /* XXX: Don't preclude handling different sized sigset_t's. */
4493 if (sigsetsize != sizeof(sigset_t))
4494 return -EINVAL;
4495
4496 if (get_compat_sigset(&newset, unewset))
4497 return -EFAULT;
4498 return sigsuspend(&newset);
4499}
4500#endif
4501
4502#ifdef CONFIG_OLD_SIGSUSPEND
4503SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4504{
4505 sigset_t blocked;
4506 siginitset(&blocked, mask);
4507 return sigsuspend(&blocked);
4508}
4509#endif
4510#ifdef CONFIG_OLD_SIGSUSPEND3
4511SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4512{
4513 sigset_t blocked;
4514 siginitset(&blocked, mask);
4515 return sigsuspend(&blocked);
4516}
4517#endif
4518
4519__weak const char *arch_vma_name(struct vm_area_struct *vma)
4520{
4521 return NULL;
4522}
4523
4524static inline void siginfo_buildtime_checks(void)
4525{
4526 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4527
4528 /* Verify the offsets in the two siginfos match */
4529#define CHECK_OFFSET(field) \
4530 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4531
4532 /* kill */
4533 CHECK_OFFSET(si_pid);
4534 CHECK_OFFSET(si_uid);
4535
4536 /* timer */
4537 CHECK_OFFSET(si_tid);
4538 CHECK_OFFSET(si_overrun);
4539 CHECK_OFFSET(si_value);
4540
4541 /* rt */
4542 CHECK_OFFSET(si_pid);
4543 CHECK_OFFSET(si_uid);
4544 CHECK_OFFSET(si_value);
4545
4546 /* sigchld */
4547 CHECK_OFFSET(si_pid);
4548 CHECK_OFFSET(si_uid);
4549 CHECK_OFFSET(si_status);
4550 CHECK_OFFSET(si_utime);
4551 CHECK_OFFSET(si_stime);
4552
4553 /* sigfault */
4554 CHECK_OFFSET(si_addr);
4555 CHECK_OFFSET(si_addr_lsb);
4556 CHECK_OFFSET(si_lower);
4557 CHECK_OFFSET(si_upper);
4558 CHECK_OFFSET(si_pkey);
4559
4560 /* sigpoll */
4561 CHECK_OFFSET(si_band);
4562 CHECK_OFFSET(si_fd);
4563
4564 /* sigsys */
4565 CHECK_OFFSET(si_call_addr);
4566 CHECK_OFFSET(si_syscall);
4567 CHECK_OFFSET(si_arch);
4568#undef CHECK_OFFSET
4569
4570 /* usb asyncio */
4571 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4572 offsetof(struct siginfo, si_addr));
4573 if (sizeof(int) == sizeof(void __user *)) {
4574 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4575 sizeof(void __user *));
4576 } else {
4577 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4578 sizeof_field(struct siginfo, si_uid)) !=
4579 sizeof(void __user *));
4580 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4581 offsetof(struct siginfo, si_uid));
4582 }
4583#ifdef CONFIG_COMPAT
4584 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4585 offsetof(struct compat_siginfo, si_addr));
4586 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4587 sizeof(compat_uptr_t));
4588 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4589 sizeof_field(struct siginfo, si_pid));
4590#endif
4591}
4592
4593void __init signals_init(void)
4594{
4595 siginfo_buildtime_checks();
4596
4597 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4598}
4599
4600#ifdef CONFIG_KGDB_KDB
4601#include <linux/kdb.h>
4602/*
4603 * kdb_send_sig - Allows kdb to send signals without exposing
4604 * signal internals. This function checks if the required locks are
4605 * available before calling the main signal code, to avoid kdb
4606 * deadlocks.
4607 */
4608void kdb_send_sig(struct task_struct *t, int sig)
4609{
4610 static struct task_struct *kdb_prev_t;
4611 int new_t, ret;
4612 if (!spin_trylock(&t->sighand->siglock)) {
4613 kdb_printf("Can't do kill command now.\n"
4614 "The sigmask lock is held somewhere else in "
4615 "kernel, try again later\n");
4616 return;
4617 }
4618 new_t = kdb_prev_t != t;
4619 kdb_prev_t = t;
4620 if (t->state != TASK_RUNNING && new_t) {
4621 spin_unlock(&t->sighand->siglock);
4622 kdb_printf("Process is not RUNNING, sending a signal from "
4623 "kdb risks deadlock\n"
4624 "on the run queue locks. "
4625 "The signal has _not_ been sent.\n"
4626 "Reissue the kill command if you want to risk "
4627 "the deadlock.\n");
4628 return;
4629 }
4630 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4631 spin_unlock(&t->sighand->siglock);
4632 if (ret)
4633 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4634 sig, t->pid);
4635 else
4636 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4637}
4638#endif /* CONFIG_KGDB_KDB */