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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/*
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 <asm/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 printk(KERN_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 int 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 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
281 }
282}
283
284/**
285 * task_clear_jobctl_pending - clear jobctl pending bits
286 * @task: target task
287 * @mask: pending bits to clear
288 *
289 * Clear @mask from @task->jobctl. @mask must be subset of
290 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
291 * STOP bits are cleared together.
292 *
293 * If clearing of @mask leaves no stop or trap pending, this function calls
294 * task_clear_jobctl_trapping().
295 *
296 * CONTEXT:
297 * Must be called with @task->sighand->siglock held.
298 */
299void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
300{
301 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
302
303 if (mask & JOBCTL_STOP_PENDING)
304 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
305
306 task->jobctl &= ~mask;
307
308 if (!(task->jobctl & JOBCTL_PENDING_MASK))
309 task_clear_jobctl_trapping(task);
310}
311
312/**
313 * task_participate_group_stop - participate in a group stop
314 * @task: task participating in a group stop
315 *
316 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
317 * Group stop states are cleared and the group stop count is consumed if
318 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
319 * stop, the appropriate %SIGNAL_* flags are set.
320 *
321 * CONTEXT:
322 * Must be called with @task->sighand->siglock held.
323 *
324 * RETURNS:
325 * %true if group stop completion should be notified to the parent, %false
326 * otherwise.
327 */
328static bool task_participate_group_stop(struct task_struct *task)
329{
330 struct signal_struct *sig = task->signal;
331 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
332
333 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
334
335 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
336
337 if (!consume)
338 return false;
339
340 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
341 sig->group_stop_count--;
342
343 /*
344 * Tell the caller to notify completion iff we are entering into a
345 * fresh group stop. Read comment in do_signal_stop() for details.
346 */
347 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
348 sig->flags = SIGNAL_STOP_STOPPED;
349 return true;
350 }
351 return false;
352}
353
354/*
355 * allocate a new signal queue record
356 * - this may be called without locks if and only if t == current, otherwise an
357 * appropriate lock must be held to stop the target task from exiting
358 */
359static struct sigqueue *
360__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
361{
362 struct sigqueue *q = NULL;
363 struct user_struct *user;
364
365 /*
366 * Protect access to @t credentials. This can go away when all
367 * callers hold rcu read lock.
368 */
369 rcu_read_lock();
370 user = get_uid(__task_cred(t)->user);
371 atomic_inc(&user->sigpending);
372 rcu_read_unlock();
373
374 if (override_rlimit ||
375 atomic_read(&user->sigpending) <=
376 task_rlimit(t, RLIMIT_SIGPENDING)) {
377 q = kmem_cache_alloc(sigqueue_cachep, flags);
378 } else {
379 print_dropped_signal(sig);
380 }
381
382 if (unlikely(q == NULL)) {
383 atomic_dec(&user->sigpending);
384 free_uid(user);
385 } else {
386 INIT_LIST_HEAD(&q->list);
387 q->flags = 0;
388 q->user = user;
389 }
390
391 return q;
392}
393
394static void __sigqueue_free(struct sigqueue *q)
395{
396 if (q->flags & SIGQUEUE_PREALLOC)
397 return;
398 atomic_dec(&q->user->sigpending);
399 free_uid(q->user);
400 kmem_cache_free(sigqueue_cachep, q);
401}
402
403void flush_sigqueue(struct sigpending *queue)
404{
405 struct sigqueue *q;
406
407 sigemptyset(&queue->signal);
408 while (!list_empty(&queue->list)) {
409 q = list_entry(queue->list.next, struct sigqueue , list);
410 list_del_init(&q->list);
411 __sigqueue_free(q);
412 }
413}
414
415/*
416 * Flush all pending signals for a task.
417 */
418void __flush_signals(struct task_struct *t)
419{
420 clear_tsk_thread_flag(t, TIF_SIGPENDING);
421 flush_sigqueue(&t->pending);
422 flush_sigqueue(&t->signal->shared_pending);
423}
424
425void flush_signals(struct task_struct *t)
426{
427 unsigned long flags;
428
429 spin_lock_irqsave(&t->sighand->siglock, flags);
430 __flush_signals(t);
431 spin_unlock_irqrestore(&t->sighand->siglock, flags);
432}
433
434static void __flush_itimer_signals(struct sigpending *pending)
435{
436 sigset_t signal, retain;
437 struct sigqueue *q, *n;
438
439 signal = pending->signal;
440 sigemptyset(&retain);
441
442 list_for_each_entry_safe(q, n, &pending->list, list) {
443 int sig = q->info.si_signo;
444
445 if (likely(q->info.si_code != SI_TIMER)) {
446 sigaddset(&retain, sig);
447 } else {
448 sigdelset(&signal, sig);
449 list_del_init(&q->list);
450 __sigqueue_free(q);
451 }
452 }
453
454 sigorsets(&pending->signal, &signal, &retain);
455}
456
457void flush_itimer_signals(void)
458{
459 struct task_struct *tsk = current;
460 unsigned long flags;
461
462 spin_lock_irqsave(&tsk->sighand->siglock, flags);
463 __flush_itimer_signals(&tsk->pending);
464 __flush_itimer_signals(&tsk->signal->shared_pending);
465 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
466}
467
468void ignore_signals(struct task_struct *t)
469{
470 int i;
471
472 for (i = 0; i < _NSIG; ++i)
473 t->sighand->action[i].sa.sa_handler = SIG_IGN;
474
475 flush_signals(t);
476}
477
478/*
479 * Flush all handlers for a task.
480 */
481
482void
483flush_signal_handlers(struct task_struct *t, int force_default)
484{
485 int i;
486 struct k_sigaction *ka = &t->sighand->action[0];
487 for (i = _NSIG ; i != 0 ; i--) {
488 if (force_default || ka->sa.sa_handler != SIG_IGN)
489 ka->sa.sa_handler = SIG_DFL;
490 ka->sa.sa_flags = 0;
491#ifdef __ARCH_HAS_SA_RESTORER
492 ka->sa.sa_restorer = NULL;
493#endif
494 sigemptyset(&ka->sa.sa_mask);
495 ka++;
496 }
497}
498
499int unhandled_signal(struct task_struct *tsk, int sig)
500{
501 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
502 if (is_global_init(tsk))
503 return 1;
504 if (handler != SIG_IGN && handler != SIG_DFL)
505 return 0;
506 /* if ptraced, let the tracer determine */
507 return !tsk->ptrace;
508}
509
510/*
511 * Notify the system that a driver wants to block all signals for this
512 * process, and wants to be notified if any signals at all were to be
513 * sent/acted upon. If the notifier routine returns non-zero, then the
514 * signal will be acted upon after all. If the notifier routine returns 0,
515 * then then signal will be blocked. Only one block per process is
516 * allowed. priv is a pointer to private data that the notifier routine
517 * can use to determine if the signal should be blocked or not.
518 */
519void
520block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
521{
522 unsigned long flags;
523
524 spin_lock_irqsave(¤t->sighand->siglock, flags);
525 current->notifier_mask = mask;
526 current->notifier_data = priv;
527 current->notifier = notifier;
528 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
529}
530
531/* Notify the system that blocking has ended. */
532
533void
534unblock_all_signals(void)
535{
536 unsigned long flags;
537
538 spin_lock_irqsave(¤t->sighand->siglock, flags);
539 current->notifier = NULL;
540 current->notifier_data = NULL;
541 recalc_sigpending();
542 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
543}
544
545static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
546{
547 struct sigqueue *q, *first = NULL;
548
549 /*
550 * Collect the siginfo appropriate to this signal. Check if
551 * there is another siginfo for the same signal.
552 */
553 list_for_each_entry(q, &list->list, list) {
554 if (q->info.si_signo == sig) {
555 if (first)
556 goto still_pending;
557 first = q;
558 }
559 }
560
561 sigdelset(&list->signal, sig);
562
563 if (first) {
564still_pending:
565 list_del_init(&first->list);
566 copy_siginfo(info, &first->info);
567 __sigqueue_free(first);
568 } else {
569 /*
570 * Ok, it wasn't in the queue. This must be
571 * a fast-pathed signal or we must have been
572 * out of queue space. So zero out the info.
573 */
574 info->si_signo = sig;
575 info->si_errno = 0;
576 info->si_code = SI_USER;
577 info->si_pid = 0;
578 info->si_uid = 0;
579 }
580}
581
582static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
583 siginfo_t *info)
584{
585 int sig = next_signal(pending, mask);
586
587 if (sig) {
588 if (current->notifier) {
589 if (sigismember(current->notifier_mask, sig)) {
590 if (!(current->notifier)(current->notifier_data)) {
591 clear_thread_flag(TIF_SIGPENDING);
592 return 0;
593 }
594 }
595 }
596
597 collect_signal(sig, pending, info);
598 }
599
600 return sig;
601}
602
603/*
604 * Dequeue a signal and return the element to the caller, which is
605 * expected to free it.
606 *
607 * All callers have to hold the siglock.
608 */
609int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
610{
611 int signr;
612
613 /* We only dequeue private signals from ourselves, we don't let
614 * signalfd steal them
615 */
616 signr = __dequeue_signal(&tsk->pending, mask, info);
617 if (!signr) {
618 signr = __dequeue_signal(&tsk->signal->shared_pending,
619 mask, info);
620 /*
621 * itimer signal ?
622 *
623 * itimers are process shared and we restart periodic
624 * itimers in the signal delivery path to prevent DoS
625 * attacks in the high resolution timer case. This is
626 * compliant with the old way of self-restarting
627 * itimers, as the SIGALRM is a legacy signal and only
628 * queued once. Changing the restart behaviour to
629 * restart the timer in the signal dequeue path is
630 * reducing the timer noise on heavy loaded !highres
631 * systems too.
632 */
633 if (unlikely(signr == SIGALRM)) {
634 struct hrtimer *tmr = &tsk->signal->real_timer;
635
636 if (!hrtimer_is_queued(tmr) &&
637 tsk->signal->it_real_incr.tv64 != 0) {
638 hrtimer_forward(tmr, tmr->base->get_time(),
639 tsk->signal->it_real_incr);
640 hrtimer_restart(tmr);
641 }
642 }
643 }
644
645 recalc_sigpending();
646 if (!signr)
647 return 0;
648
649 if (unlikely(sig_kernel_stop(signr))) {
650 /*
651 * Set a marker that we have dequeued a stop signal. Our
652 * caller might release the siglock and then the pending
653 * stop signal it is about to process is no longer in the
654 * pending bitmasks, but must still be cleared by a SIGCONT
655 * (and overruled by a SIGKILL). So those cases clear this
656 * shared flag after we've set it. Note that this flag may
657 * remain set after the signal we return is ignored or
658 * handled. That doesn't matter because its only purpose
659 * is to alert stop-signal processing code when another
660 * processor has come along and cleared the flag.
661 */
662 current->jobctl |= JOBCTL_STOP_DEQUEUED;
663 }
664 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
665 /*
666 * Release the siglock to ensure proper locking order
667 * of timer locks outside of siglocks. Note, we leave
668 * irqs disabled here, since the posix-timers code is
669 * about to disable them again anyway.
670 */
671 spin_unlock(&tsk->sighand->siglock);
672 do_schedule_next_timer(info);
673 spin_lock(&tsk->sighand->siglock);
674 }
675 return signr;
676}
677
678/*
679 * Tell a process that it has a new active signal..
680 *
681 * NOTE! we rely on the previous spin_lock to
682 * lock interrupts for us! We can only be called with
683 * "siglock" held, and the local interrupt must
684 * have been disabled when that got acquired!
685 *
686 * No need to set need_resched since signal event passing
687 * goes through ->blocked
688 */
689void signal_wake_up_state(struct task_struct *t, unsigned int state)
690{
691 set_tsk_thread_flag(t, TIF_SIGPENDING);
692 /*
693 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
694 * case. We don't check t->state here because there is a race with it
695 * executing another processor and just now entering stopped state.
696 * By using wake_up_state, we ensure the process will wake up and
697 * handle its death signal.
698 */
699 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
700 kick_process(t);
701}
702
703/*
704 * Remove signals in mask from the pending set and queue.
705 * Returns 1 if any signals were found.
706 *
707 * All callers must be holding the siglock.
708 *
709 * This version takes a sigset mask and looks at all signals,
710 * not just those in the first mask word.
711 */
712static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
713{
714 struct sigqueue *q, *n;
715 sigset_t m;
716
717 sigandsets(&m, mask, &s->signal);
718 if (sigisemptyset(&m))
719 return 0;
720
721 sigandnsets(&s->signal, &s->signal, mask);
722 list_for_each_entry_safe(q, n, &s->list, list) {
723 if (sigismember(mask, q->info.si_signo)) {
724 list_del_init(&q->list);
725 __sigqueue_free(q);
726 }
727 }
728 return 1;
729}
730/*
731 * Remove signals in mask from the pending set and queue.
732 * Returns 1 if any signals were found.
733 *
734 * All callers must be holding the siglock.
735 */
736static int rm_from_queue(unsigned long mask, struct sigpending *s)
737{
738 struct sigqueue *q, *n;
739
740 if (!sigtestsetmask(&s->signal, mask))
741 return 0;
742
743 sigdelsetmask(&s->signal, mask);
744 list_for_each_entry_safe(q, n, &s->list, list) {
745 if (q->info.si_signo < SIGRTMIN &&
746 (mask & sigmask(q->info.si_signo))) {
747 list_del_init(&q->list);
748 __sigqueue_free(q);
749 }
750 }
751 return 1;
752}
753
754static inline int is_si_special(const struct siginfo *info)
755{
756 return info <= SEND_SIG_FORCED;
757}
758
759static inline bool si_fromuser(const struct siginfo *info)
760{
761 return info == SEND_SIG_NOINFO ||
762 (!is_si_special(info) && SI_FROMUSER(info));
763}
764
765/*
766 * called with RCU read lock from check_kill_permission()
767 */
768static int kill_ok_by_cred(struct task_struct *t)
769{
770 const struct cred *cred = current_cred();
771 const struct cred *tcred = __task_cred(t);
772
773 if (uid_eq(cred->euid, tcred->suid) ||
774 uid_eq(cred->euid, tcred->uid) ||
775 uid_eq(cred->uid, tcred->suid) ||
776 uid_eq(cred->uid, tcred->uid))
777 return 1;
778
779 if (ns_capable(tcred->user_ns, CAP_KILL))
780 return 1;
781
782 return 0;
783}
784
785/*
786 * Bad permissions for sending the signal
787 * - the caller must hold the RCU read lock
788 */
789static int check_kill_permission(int sig, struct siginfo *info,
790 struct task_struct *t)
791{
792 struct pid *sid;
793 int error;
794
795 if (!valid_signal(sig))
796 return -EINVAL;
797
798 if (!si_fromuser(info))
799 return 0;
800
801 error = audit_signal_info(sig, t); /* Let audit system see the signal */
802 if (error)
803 return error;
804
805 if (!same_thread_group(current, t) &&
806 !kill_ok_by_cred(t)) {
807 switch (sig) {
808 case SIGCONT:
809 sid = task_session(t);
810 /*
811 * We don't return the error if sid == NULL. The
812 * task was unhashed, the caller must notice this.
813 */
814 if (!sid || sid == task_session(current))
815 break;
816 default:
817 return -EPERM;
818 }
819 }
820
821 return security_task_kill(t, info, sig, 0);
822}
823
824/**
825 * ptrace_trap_notify - schedule trap to notify ptracer
826 * @t: tracee wanting to notify tracer
827 *
828 * This function schedules sticky ptrace trap which is cleared on the next
829 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
830 * ptracer.
831 *
832 * If @t is running, STOP trap will be taken. If trapped for STOP and
833 * ptracer is listening for events, tracee is woken up so that it can
834 * re-trap for the new event. If trapped otherwise, STOP trap will be
835 * eventually taken without returning to userland after the existing traps
836 * are finished by PTRACE_CONT.
837 *
838 * CONTEXT:
839 * Must be called with @task->sighand->siglock held.
840 */
841static void ptrace_trap_notify(struct task_struct *t)
842{
843 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
844 assert_spin_locked(&t->sighand->siglock);
845
846 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
847 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
848}
849
850/*
851 * Handle magic process-wide effects of stop/continue signals. Unlike
852 * the signal actions, these happen immediately at signal-generation
853 * time regardless of blocking, ignoring, or handling. This does the
854 * actual continuing for SIGCONT, but not the actual stopping for stop
855 * signals. The process stop is done as a signal action for SIG_DFL.
856 *
857 * Returns true if the signal should be actually delivered, otherwise
858 * it should be dropped.
859 */
860static bool prepare_signal(int sig, struct task_struct *p, bool force)
861{
862 struct signal_struct *signal = p->signal;
863 struct task_struct *t;
864
865 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
866 if (signal->flags & SIGNAL_GROUP_COREDUMP)
867 return sig == SIGKILL;
868 /*
869 * The process is in the middle of dying, nothing to do.
870 */
871 } else if (sig_kernel_stop(sig)) {
872 /*
873 * This is a stop signal. Remove SIGCONT from all queues.
874 */
875 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
876 t = p;
877 do {
878 rm_from_queue(sigmask(SIGCONT), &t->pending);
879 } while_each_thread(p, t);
880 } else if (sig == SIGCONT) {
881 unsigned int why;
882 /*
883 * Remove all stop signals from all queues, wake all threads.
884 */
885 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
886 t = p;
887 do {
888 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
889 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
890 if (likely(!(t->ptrace & PT_SEIZED)))
891 wake_up_state(t, __TASK_STOPPED);
892 else
893 ptrace_trap_notify(t);
894 } while_each_thread(p, t);
895
896 /*
897 * Notify the parent with CLD_CONTINUED if we were stopped.
898 *
899 * If we were in the middle of a group stop, we pretend it
900 * was already finished, and then continued. Since SIGCHLD
901 * doesn't queue we report only CLD_STOPPED, as if the next
902 * CLD_CONTINUED was dropped.
903 */
904 why = 0;
905 if (signal->flags & SIGNAL_STOP_STOPPED)
906 why |= SIGNAL_CLD_CONTINUED;
907 else if (signal->group_stop_count)
908 why |= SIGNAL_CLD_STOPPED;
909
910 if (why) {
911 /*
912 * The first thread which returns from do_signal_stop()
913 * will take ->siglock, notice SIGNAL_CLD_MASK, and
914 * notify its parent. See get_signal_to_deliver().
915 */
916 signal->flags = why | SIGNAL_STOP_CONTINUED;
917 signal->group_stop_count = 0;
918 signal->group_exit_code = 0;
919 }
920 }
921
922 return !sig_ignored(p, sig, force);
923}
924
925/*
926 * Test if P wants to take SIG. After we've checked all threads with this,
927 * it's equivalent to finding no threads not blocking SIG. Any threads not
928 * blocking SIG were ruled out because they are not running and already
929 * have pending signals. Such threads will dequeue from the shared queue
930 * as soon as they're available, so putting the signal on the shared queue
931 * will be equivalent to sending it to one such thread.
932 */
933static inline int wants_signal(int sig, struct task_struct *p)
934{
935 if (sigismember(&p->blocked, sig))
936 return 0;
937 if (p->flags & PF_EXITING)
938 return 0;
939 if (sig == SIGKILL)
940 return 1;
941 if (task_is_stopped_or_traced(p))
942 return 0;
943 return task_curr(p) || !signal_pending(p);
944}
945
946static void complete_signal(int sig, struct task_struct *p, int group)
947{
948 struct signal_struct *signal = p->signal;
949 struct task_struct *t;
950
951 /*
952 * Now find a thread we can wake up to take the signal off the queue.
953 *
954 * If the main thread wants the signal, it gets first crack.
955 * Probably the least surprising to the average bear.
956 */
957 if (wants_signal(sig, p))
958 t = p;
959 else if (!group || thread_group_empty(p))
960 /*
961 * There is just one thread and it does not need to be woken.
962 * It will dequeue unblocked signals before it runs again.
963 */
964 return;
965 else {
966 /*
967 * Otherwise try to find a suitable thread.
968 */
969 t = signal->curr_target;
970 while (!wants_signal(sig, t)) {
971 t = next_thread(t);
972 if (t == signal->curr_target)
973 /*
974 * No thread needs to be woken.
975 * Any eligible threads will see
976 * the signal in the queue soon.
977 */
978 return;
979 }
980 signal->curr_target = t;
981 }
982
983 /*
984 * Found a killable thread. If the signal will be fatal,
985 * then start taking the whole group down immediately.
986 */
987 if (sig_fatal(p, sig) &&
988 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
989 !sigismember(&t->real_blocked, sig) &&
990 (sig == SIGKILL || !t->ptrace)) {
991 /*
992 * This signal will be fatal to the whole group.
993 */
994 if (!sig_kernel_coredump(sig)) {
995 /*
996 * Start a group exit and wake everybody up.
997 * This way we don't have other threads
998 * running and doing things after a slower
999 * thread has the fatal signal pending.
1000 */
1001 signal->flags = SIGNAL_GROUP_EXIT;
1002 signal->group_exit_code = sig;
1003 signal->group_stop_count = 0;
1004 t = p;
1005 do {
1006 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1007 sigaddset(&t->pending.signal, SIGKILL);
1008 signal_wake_up(t, 1);
1009 } while_each_thread(p, t);
1010 return;
1011 }
1012 }
1013
1014 /*
1015 * The signal is already in the shared-pending queue.
1016 * Tell the chosen thread to wake up and dequeue it.
1017 */
1018 signal_wake_up(t, sig == SIGKILL);
1019 return;
1020}
1021
1022static inline int legacy_queue(struct sigpending *signals, int sig)
1023{
1024 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1025}
1026
1027#ifdef CONFIG_USER_NS
1028static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1029{
1030 if (current_user_ns() == task_cred_xxx(t, user_ns))
1031 return;
1032
1033 if (SI_FROMKERNEL(info))
1034 return;
1035
1036 rcu_read_lock();
1037 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1038 make_kuid(current_user_ns(), info->si_uid));
1039 rcu_read_unlock();
1040}
1041#else
1042static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1043{
1044 return;
1045}
1046#endif
1047
1048static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1049 int group, int from_ancestor_ns)
1050{
1051 struct sigpending *pending;
1052 struct sigqueue *q;
1053 int override_rlimit;
1054 int ret = 0, result;
1055
1056 assert_spin_locked(&t->sighand->siglock);
1057
1058 result = TRACE_SIGNAL_IGNORED;
1059 if (!prepare_signal(sig, t,
1060 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1061 goto ret;
1062
1063 pending = group ? &t->signal->shared_pending : &t->pending;
1064 /*
1065 * Short-circuit ignored signals and support queuing
1066 * exactly one non-rt signal, so that we can get more
1067 * detailed information about the cause of the signal.
1068 */
1069 result = TRACE_SIGNAL_ALREADY_PENDING;
1070 if (legacy_queue(pending, sig))
1071 goto ret;
1072
1073 result = TRACE_SIGNAL_DELIVERED;
1074 /*
1075 * fast-pathed signals for kernel-internal things like SIGSTOP
1076 * or SIGKILL.
1077 */
1078 if (info == SEND_SIG_FORCED)
1079 goto out_set;
1080
1081 /*
1082 * Real-time signals must be queued if sent by sigqueue, or
1083 * some other real-time mechanism. It is implementation
1084 * defined whether kill() does so. We attempt to do so, on
1085 * the principle of least surprise, but since kill is not
1086 * allowed to fail with EAGAIN when low on memory we just
1087 * make sure at least one signal gets delivered and don't
1088 * pass on the info struct.
1089 */
1090 if (sig < SIGRTMIN)
1091 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1092 else
1093 override_rlimit = 0;
1094
1095 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1096 override_rlimit);
1097 if (q) {
1098 list_add_tail(&q->list, &pending->list);
1099 switch ((unsigned long) info) {
1100 case (unsigned long) SEND_SIG_NOINFO:
1101 q->info.si_signo = sig;
1102 q->info.si_errno = 0;
1103 q->info.si_code = SI_USER;
1104 q->info.si_pid = task_tgid_nr_ns(current,
1105 task_active_pid_ns(t));
1106 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1107 break;
1108 case (unsigned long) SEND_SIG_PRIV:
1109 q->info.si_signo = sig;
1110 q->info.si_errno = 0;
1111 q->info.si_code = SI_KERNEL;
1112 q->info.si_pid = 0;
1113 q->info.si_uid = 0;
1114 break;
1115 default:
1116 copy_siginfo(&q->info, info);
1117 if (from_ancestor_ns)
1118 q->info.si_pid = 0;
1119 break;
1120 }
1121
1122 userns_fixup_signal_uid(&q->info, t);
1123
1124 } else if (!is_si_special(info)) {
1125 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1126 /*
1127 * Queue overflow, abort. We may abort if the
1128 * signal was rt and sent by user using something
1129 * other than kill().
1130 */
1131 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1132 ret = -EAGAIN;
1133 goto ret;
1134 } else {
1135 /*
1136 * This is a silent loss of information. We still
1137 * send the signal, but the *info bits are lost.
1138 */
1139 result = TRACE_SIGNAL_LOSE_INFO;
1140 }
1141 }
1142
1143out_set:
1144 signalfd_notify(t, sig);
1145 sigaddset(&pending->signal, sig);
1146 complete_signal(sig, t, group);
1147ret:
1148 trace_signal_generate(sig, info, t, group, result);
1149 return ret;
1150}
1151
1152static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1153 int group)
1154{
1155 int from_ancestor_ns = 0;
1156
1157#ifdef CONFIG_PID_NS
1158 from_ancestor_ns = si_fromuser(info) &&
1159 !task_pid_nr_ns(current, task_active_pid_ns(t));
1160#endif
1161
1162 return __send_signal(sig, info, t, group, from_ancestor_ns);
1163}
1164
1165static void print_fatal_signal(int signr)
1166{
1167 struct pt_regs *regs = signal_pt_regs();
1168 printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1169
1170#if defined(__i386__) && !defined(__arch_um__)
1171 printk(KERN_INFO "code at %08lx: ", regs->ip);
1172 {
1173 int i;
1174 for (i = 0; i < 16; i++) {
1175 unsigned char insn;
1176
1177 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1178 break;
1179 printk(KERN_CONT "%02x ", insn);
1180 }
1181 }
1182 printk(KERN_CONT "\n");
1183#endif
1184 preempt_disable();
1185 show_regs(regs);
1186 preempt_enable();
1187}
1188
1189static int __init setup_print_fatal_signals(char *str)
1190{
1191 get_option (&str, &print_fatal_signals);
1192
1193 return 1;
1194}
1195
1196__setup("print-fatal-signals=", setup_print_fatal_signals);
1197
1198int
1199__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1200{
1201 return send_signal(sig, info, p, 1);
1202}
1203
1204static int
1205specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1206{
1207 return send_signal(sig, info, t, 0);
1208}
1209
1210int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1211 bool group)
1212{
1213 unsigned long flags;
1214 int ret = -ESRCH;
1215
1216 if (lock_task_sighand(p, &flags)) {
1217 ret = send_signal(sig, info, p, group);
1218 unlock_task_sighand(p, &flags);
1219 }
1220
1221 return ret;
1222}
1223
1224/*
1225 * Force a signal that the process can't ignore: if necessary
1226 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1227 *
1228 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1229 * since we do not want to have a signal handler that was blocked
1230 * be invoked when user space had explicitly blocked it.
1231 *
1232 * We don't want to have recursive SIGSEGV's etc, for example,
1233 * that is why we also clear SIGNAL_UNKILLABLE.
1234 */
1235int
1236force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1237{
1238 unsigned long int flags;
1239 int ret, blocked, ignored;
1240 struct k_sigaction *action;
1241
1242 spin_lock_irqsave(&t->sighand->siglock, flags);
1243 action = &t->sighand->action[sig-1];
1244 ignored = action->sa.sa_handler == SIG_IGN;
1245 blocked = sigismember(&t->blocked, sig);
1246 if (blocked || ignored) {
1247 action->sa.sa_handler = SIG_DFL;
1248 if (blocked) {
1249 sigdelset(&t->blocked, sig);
1250 recalc_sigpending_and_wake(t);
1251 }
1252 }
1253 if (action->sa.sa_handler == SIG_DFL)
1254 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1255 ret = specific_send_sig_info(sig, info, t);
1256 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1257
1258 return ret;
1259}
1260
1261/*
1262 * Nuke all other threads in the group.
1263 */
1264int zap_other_threads(struct task_struct *p)
1265{
1266 struct task_struct *t = p;
1267 int count = 0;
1268
1269 p->signal->group_stop_count = 0;
1270
1271 while_each_thread(p, t) {
1272 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1273 count++;
1274
1275 /* Don't bother with already dead threads */
1276 if (t->exit_state)
1277 continue;
1278 sigaddset(&t->pending.signal, SIGKILL);
1279 signal_wake_up(t, 1);
1280 }
1281
1282 return count;
1283}
1284
1285struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1286 unsigned long *flags)
1287{
1288 struct sighand_struct *sighand;
1289
1290 for (;;) {
1291 local_irq_save(*flags);
1292 rcu_read_lock();
1293 sighand = rcu_dereference(tsk->sighand);
1294 if (unlikely(sighand == NULL)) {
1295 rcu_read_unlock();
1296 local_irq_restore(*flags);
1297 break;
1298 }
1299
1300 spin_lock(&sighand->siglock);
1301 if (likely(sighand == tsk->sighand)) {
1302 rcu_read_unlock();
1303 break;
1304 }
1305 spin_unlock(&sighand->siglock);
1306 rcu_read_unlock();
1307 local_irq_restore(*flags);
1308 }
1309
1310 return sighand;
1311}
1312
1313/*
1314 * send signal info to all the members of a group
1315 */
1316int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1317{
1318 int ret;
1319
1320 rcu_read_lock();
1321 ret = check_kill_permission(sig, info, p);
1322 rcu_read_unlock();
1323
1324 if (!ret && sig)
1325 ret = do_send_sig_info(sig, info, p, true);
1326
1327 return ret;
1328}
1329
1330/*
1331 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1332 * control characters do (^C, ^Z etc)
1333 * - the caller must hold at least a readlock on tasklist_lock
1334 */
1335int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1336{
1337 struct task_struct *p = NULL;
1338 int retval, success;
1339
1340 success = 0;
1341 retval = -ESRCH;
1342 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1343 int err = group_send_sig_info(sig, info, p);
1344 success |= !err;
1345 retval = err;
1346 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1347 return success ? 0 : retval;
1348}
1349
1350int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1351{
1352 int error = -ESRCH;
1353 struct task_struct *p;
1354
1355 rcu_read_lock();
1356retry:
1357 p = pid_task(pid, PIDTYPE_PID);
1358 if (p) {
1359 error = group_send_sig_info(sig, info, p);
1360 if (unlikely(error == -ESRCH))
1361 /*
1362 * The task was unhashed in between, try again.
1363 * If it is dead, pid_task() will return NULL,
1364 * if we race with de_thread() it will find the
1365 * new leader.
1366 */
1367 goto retry;
1368 }
1369 rcu_read_unlock();
1370
1371 return error;
1372}
1373
1374int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1375{
1376 int error;
1377 rcu_read_lock();
1378 error = kill_pid_info(sig, info, find_vpid(pid));
1379 rcu_read_unlock();
1380 return error;
1381}
1382
1383static int kill_as_cred_perm(const struct cred *cred,
1384 struct task_struct *target)
1385{
1386 const struct cred *pcred = __task_cred(target);
1387 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1388 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1389 return 0;
1390 return 1;
1391}
1392
1393/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1394int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1395 const struct cred *cred, u32 secid)
1396{
1397 int ret = -EINVAL;
1398 struct task_struct *p;
1399 unsigned long flags;
1400
1401 if (!valid_signal(sig))
1402 return ret;
1403
1404 rcu_read_lock();
1405 p = pid_task(pid, PIDTYPE_PID);
1406 if (!p) {
1407 ret = -ESRCH;
1408 goto out_unlock;
1409 }
1410 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1411 ret = -EPERM;
1412 goto out_unlock;
1413 }
1414 ret = security_task_kill(p, info, sig, secid);
1415 if (ret)
1416 goto out_unlock;
1417
1418 if (sig) {
1419 if (lock_task_sighand(p, &flags)) {
1420 ret = __send_signal(sig, info, p, 1, 0);
1421 unlock_task_sighand(p, &flags);
1422 } else
1423 ret = -ESRCH;
1424 }
1425out_unlock:
1426 rcu_read_unlock();
1427 return ret;
1428}
1429EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1430
1431/*
1432 * kill_something_info() interprets pid in interesting ways just like kill(2).
1433 *
1434 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1435 * is probably wrong. Should make it like BSD or SYSV.
1436 */
1437
1438static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1439{
1440 int ret;
1441
1442 if (pid > 0) {
1443 rcu_read_lock();
1444 ret = kill_pid_info(sig, info, find_vpid(pid));
1445 rcu_read_unlock();
1446 return ret;
1447 }
1448
1449 read_lock(&tasklist_lock);
1450 if (pid != -1) {
1451 ret = __kill_pgrp_info(sig, info,
1452 pid ? find_vpid(-pid) : task_pgrp(current));
1453 } else {
1454 int retval = 0, count = 0;
1455 struct task_struct * p;
1456
1457 for_each_process(p) {
1458 if (task_pid_vnr(p) > 1 &&
1459 !same_thread_group(p, current)) {
1460 int err = group_send_sig_info(sig, info, p);
1461 ++count;
1462 if (err != -EPERM)
1463 retval = err;
1464 }
1465 }
1466 ret = count ? retval : -ESRCH;
1467 }
1468 read_unlock(&tasklist_lock);
1469
1470 return ret;
1471}
1472
1473/*
1474 * These are for backward compatibility with the rest of the kernel source.
1475 */
1476
1477int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1478{
1479 /*
1480 * Make sure legacy kernel users don't send in bad values
1481 * (normal paths check this in check_kill_permission).
1482 */
1483 if (!valid_signal(sig))
1484 return -EINVAL;
1485
1486 return do_send_sig_info(sig, info, p, false);
1487}
1488
1489#define __si_special(priv) \
1490 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1491
1492int
1493send_sig(int sig, struct task_struct *p, int priv)
1494{
1495 return send_sig_info(sig, __si_special(priv), p);
1496}
1497
1498void
1499force_sig(int sig, struct task_struct *p)
1500{
1501 force_sig_info(sig, SEND_SIG_PRIV, p);
1502}
1503
1504/*
1505 * When things go south during signal handling, we
1506 * will force a SIGSEGV. And if the signal that caused
1507 * the problem was already a SIGSEGV, we'll want to
1508 * make sure we don't even try to deliver the signal..
1509 */
1510int
1511force_sigsegv(int sig, struct task_struct *p)
1512{
1513 if (sig == SIGSEGV) {
1514 unsigned long flags;
1515 spin_lock_irqsave(&p->sighand->siglock, flags);
1516 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1517 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1518 }
1519 force_sig(SIGSEGV, p);
1520 return 0;
1521}
1522
1523int kill_pgrp(struct pid *pid, int sig, int priv)
1524{
1525 int ret;
1526
1527 read_lock(&tasklist_lock);
1528 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1529 read_unlock(&tasklist_lock);
1530
1531 return ret;
1532}
1533EXPORT_SYMBOL(kill_pgrp);
1534
1535int kill_pid(struct pid *pid, int sig, int priv)
1536{
1537 return kill_pid_info(sig, __si_special(priv), pid);
1538}
1539EXPORT_SYMBOL(kill_pid);
1540
1541/*
1542 * These functions support sending signals using preallocated sigqueue
1543 * structures. This is needed "because realtime applications cannot
1544 * afford to lose notifications of asynchronous events, like timer
1545 * expirations or I/O completions". In the case of POSIX Timers
1546 * we allocate the sigqueue structure from the timer_create. If this
1547 * allocation fails we are able to report the failure to the application
1548 * with an EAGAIN error.
1549 */
1550struct sigqueue *sigqueue_alloc(void)
1551{
1552 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1553
1554 if (q)
1555 q->flags |= SIGQUEUE_PREALLOC;
1556
1557 return q;
1558}
1559
1560void sigqueue_free(struct sigqueue *q)
1561{
1562 unsigned long flags;
1563 spinlock_t *lock = ¤t->sighand->siglock;
1564
1565 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1566 /*
1567 * We must hold ->siglock while testing q->list
1568 * to serialize with collect_signal() or with
1569 * __exit_signal()->flush_sigqueue().
1570 */
1571 spin_lock_irqsave(lock, flags);
1572 q->flags &= ~SIGQUEUE_PREALLOC;
1573 /*
1574 * If it is queued it will be freed when dequeued,
1575 * like the "regular" sigqueue.
1576 */
1577 if (!list_empty(&q->list))
1578 q = NULL;
1579 spin_unlock_irqrestore(lock, flags);
1580
1581 if (q)
1582 __sigqueue_free(q);
1583}
1584
1585int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1586{
1587 int sig = q->info.si_signo;
1588 struct sigpending *pending;
1589 unsigned long flags;
1590 int ret, result;
1591
1592 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1593
1594 ret = -1;
1595 if (!likely(lock_task_sighand(t, &flags)))
1596 goto ret;
1597
1598 ret = 1; /* the signal is ignored */
1599 result = TRACE_SIGNAL_IGNORED;
1600 if (!prepare_signal(sig, t, false))
1601 goto out;
1602
1603 ret = 0;
1604 if (unlikely(!list_empty(&q->list))) {
1605 /*
1606 * If an SI_TIMER entry is already queue just increment
1607 * the overrun count.
1608 */
1609 BUG_ON(q->info.si_code != SI_TIMER);
1610 q->info.si_overrun++;
1611 result = TRACE_SIGNAL_ALREADY_PENDING;
1612 goto out;
1613 }
1614 q->info.si_overrun = 0;
1615
1616 signalfd_notify(t, sig);
1617 pending = group ? &t->signal->shared_pending : &t->pending;
1618 list_add_tail(&q->list, &pending->list);
1619 sigaddset(&pending->signal, sig);
1620 complete_signal(sig, t, group);
1621 result = TRACE_SIGNAL_DELIVERED;
1622out:
1623 trace_signal_generate(sig, &q->info, t, group, result);
1624 unlock_task_sighand(t, &flags);
1625ret:
1626 return ret;
1627}
1628
1629/*
1630 * Let a parent know about the death of a child.
1631 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1632 *
1633 * Returns true if our parent ignored us and so we've switched to
1634 * self-reaping.
1635 */
1636bool do_notify_parent(struct task_struct *tsk, int sig)
1637{
1638 struct siginfo info;
1639 unsigned long flags;
1640 struct sighand_struct *psig;
1641 bool autoreap = false;
1642 cputime_t utime, stime;
1643
1644 BUG_ON(sig == -1);
1645
1646 /* do_notify_parent_cldstop should have been called instead. */
1647 BUG_ON(task_is_stopped_or_traced(tsk));
1648
1649 BUG_ON(!tsk->ptrace &&
1650 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1651
1652 if (sig != SIGCHLD) {
1653 /*
1654 * This is only possible if parent == real_parent.
1655 * Check if it has changed security domain.
1656 */
1657 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1658 sig = SIGCHLD;
1659 }
1660
1661 info.si_signo = sig;
1662 info.si_errno = 0;
1663 /*
1664 * We are under tasklist_lock here so our parent is tied to
1665 * us and cannot change.
1666 *
1667 * task_active_pid_ns will always return the same pid namespace
1668 * until a task passes through release_task.
1669 *
1670 * write_lock() currently calls preempt_disable() which is the
1671 * same as rcu_read_lock(), but according to Oleg, this is not
1672 * correct to rely on this
1673 */
1674 rcu_read_lock();
1675 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1676 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1677 task_uid(tsk));
1678 rcu_read_unlock();
1679
1680 task_cputime(tsk, &utime, &stime);
1681 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1682 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1683
1684 info.si_status = tsk->exit_code & 0x7f;
1685 if (tsk->exit_code & 0x80)
1686 info.si_code = CLD_DUMPED;
1687 else if (tsk->exit_code & 0x7f)
1688 info.si_code = CLD_KILLED;
1689 else {
1690 info.si_code = CLD_EXITED;
1691 info.si_status = tsk->exit_code >> 8;
1692 }
1693
1694 psig = tsk->parent->sighand;
1695 spin_lock_irqsave(&psig->siglock, flags);
1696 if (!tsk->ptrace && sig == SIGCHLD &&
1697 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1698 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1699 /*
1700 * We are exiting and our parent doesn't care. POSIX.1
1701 * defines special semantics for setting SIGCHLD to SIG_IGN
1702 * or setting the SA_NOCLDWAIT flag: we should be reaped
1703 * automatically and not left for our parent's wait4 call.
1704 * Rather than having the parent do it as a magic kind of
1705 * signal handler, we just set this to tell do_exit that we
1706 * can be cleaned up without becoming a zombie. Note that
1707 * we still call __wake_up_parent in this case, because a
1708 * blocked sys_wait4 might now return -ECHILD.
1709 *
1710 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1711 * is implementation-defined: we do (if you don't want
1712 * it, just use SIG_IGN instead).
1713 */
1714 autoreap = true;
1715 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1716 sig = 0;
1717 }
1718 if (valid_signal(sig) && sig)
1719 __group_send_sig_info(sig, &info, tsk->parent);
1720 __wake_up_parent(tsk, tsk->parent);
1721 spin_unlock_irqrestore(&psig->siglock, flags);
1722
1723 return autoreap;
1724}
1725
1726/**
1727 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1728 * @tsk: task reporting the state change
1729 * @for_ptracer: the notification is for ptracer
1730 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1731 *
1732 * Notify @tsk's parent that the stopped/continued state has changed. If
1733 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1734 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1735 *
1736 * CONTEXT:
1737 * Must be called with tasklist_lock at least read locked.
1738 */
1739static void do_notify_parent_cldstop(struct task_struct *tsk,
1740 bool for_ptracer, int why)
1741{
1742 struct siginfo info;
1743 unsigned long flags;
1744 struct task_struct *parent;
1745 struct sighand_struct *sighand;
1746 cputime_t utime, stime;
1747
1748 if (for_ptracer) {
1749 parent = tsk->parent;
1750 } else {
1751 tsk = tsk->group_leader;
1752 parent = tsk->real_parent;
1753 }
1754
1755 info.si_signo = SIGCHLD;
1756 info.si_errno = 0;
1757 /*
1758 * see comment in do_notify_parent() about the following 4 lines
1759 */
1760 rcu_read_lock();
1761 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1762 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1763 rcu_read_unlock();
1764
1765 task_cputime(tsk, &utime, &stime);
1766 info.si_utime = cputime_to_clock_t(utime);
1767 info.si_stime = cputime_to_clock_t(stime);
1768
1769 info.si_code = why;
1770 switch (why) {
1771 case CLD_CONTINUED:
1772 info.si_status = SIGCONT;
1773 break;
1774 case CLD_STOPPED:
1775 info.si_status = tsk->signal->group_exit_code & 0x7f;
1776 break;
1777 case CLD_TRAPPED:
1778 info.si_status = tsk->exit_code & 0x7f;
1779 break;
1780 default:
1781 BUG();
1782 }
1783
1784 sighand = parent->sighand;
1785 spin_lock_irqsave(&sighand->siglock, flags);
1786 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1787 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1788 __group_send_sig_info(SIGCHLD, &info, parent);
1789 /*
1790 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1791 */
1792 __wake_up_parent(tsk, parent);
1793 spin_unlock_irqrestore(&sighand->siglock, flags);
1794}
1795
1796static inline int may_ptrace_stop(void)
1797{
1798 if (!likely(current->ptrace))
1799 return 0;
1800 /*
1801 * Are we in the middle of do_coredump?
1802 * If so and our tracer is also part of the coredump stopping
1803 * is a deadlock situation, and pointless because our tracer
1804 * is dead so don't allow us to stop.
1805 * If SIGKILL was already sent before the caller unlocked
1806 * ->siglock we must see ->core_state != NULL. Otherwise it
1807 * is safe to enter schedule().
1808 *
1809 * This is almost outdated, a task with the pending SIGKILL can't
1810 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1811 * after SIGKILL was already dequeued.
1812 */
1813 if (unlikely(current->mm->core_state) &&
1814 unlikely(current->mm == current->parent->mm))
1815 return 0;
1816
1817 return 1;
1818}
1819
1820/*
1821 * Return non-zero if there is a SIGKILL that should be waking us up.
1822 * Called with the siglock held.
1823 */
1824static int sigkill_pending(struct task_struct *tsk)
1825{
1826 return sigismember(&tsk->pending.signal, SIGKILL) ||
1827 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1828}
1829
1830/*
1831 * This must be called with current->sighand->siglock held.
1832 *
1833 * This should be the path for all ptrace stops.
1834 * We always set current->last_siginfo while stopped here.
1835 * That makes it a way to test a stopped process for
1836 * being ptrace-stopped vs being job-control-stopped.
1837 *
1838 * If we actually decide not to stop at all because the tracer
1839 * is gone, we keep current->exit_code unless clear_code.
1840 */
1841static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1842 __releases(¤t->sighand->siglock)
1843 __acquires(¤t->sighand->siglock)
1844{
1845 bool gstop_done = false;
1846
1847 if (arch_ptrace_stop_needed(exit_code, info)) {
1848 /*
1849 * The arch code has something special to do before a
1850 * ptrace stop. This is allowed to block, e.g. for faults
1851 * on user stack pages. We can't keep the siglock while
1852 * calling arch_ptrace_stop, so we must release it now.
1853 * To preserve proper semantics, we must do this before
1854 * any signal bookkeeping like checking group_stop_count.
1855 * Meanwhile, a SIGKILL could come in before we retake the
1856 * siglock. That must prevent us from sleeping in TASK_TRACED.
1857 * So after regaining the lock, we must check for SIGKILL.
1858 */
1859 spin_unlock_irq(¤t->sighand->siglock);
1860 arch_ptrace_stop(exit_code, info);
1861 spin_lock_irq(¤t->sighand->siglock);
1862 if (sigkill_pending(current))
1863 return;
1864 }
1865
1866 /*
1867 * We're committing to trapping. TRACED should be visible before
1868 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1869 * Also, transition to TRACED and updates to ->jobctl should be
1870 * atomic with respect to siglock and should be done after the arch
1871 * hook as siglock is released and regrabbed across it.
1872 */
1873 set_current_state(TASK_TRACED);
1874
1875 current->last_siginfo = info;
1876 current->exit_code = exit_code;
1877
1878 /*
1879 * If @why is CLD_STOPPED, we're trapping to participate in a group
1880 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1881 * across siglock relocks since INTERRUPT was scheduled, PENDING
1882 * could be clear now. We act as if SIGCONT is received after
1883 * TASK_TRACED is entered - ignore it.
1884 */
1885 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1886 gstop_done = task_participate_group_stop(current);
1887
1888 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1889 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1890 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1891 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1892
1893 /* entering a trap, clear TRAPPING */
1894 task_clear_jobctl_trapping(current);
1895
1896 spin_unlock_irq(¤t->sighand->siglock);
1897 read_lock(&tasklist_lock);
1898 if (may_ptrace_stop()) {
1899 /*
1900 * Notify parents of the stop.
1901 *
1902 * While ptraced, there are two parents - the ptracer and
1903 * the real_parent of the group_leader. The ptracer should
1904 * know about every stop while the real parent is only
1905 * interested in the completion of group stop. The states
1906 * for the two don't interact with each other. Notify
1907 * separately unless they're gonna be duplicates.
1908 */
1909 do_notify_parent_cldstop(current, true, why);
1910 if (gstop_done && ptrace_reparented(current))
1911 do_notify_parent_cldstop(current, false, why);
1912
1913 /*
1914 * Don't want to allow preemption here, because
1915 * sys_ptrace() needs this task to be inactive.
1916 *
1917 * XXX: implement read_unlock_no_resched().
1918 */
1919 preempt_disable();
1920 read_unlock(&tasklist_lock);
1921 preempt_enable_no_resched();
1922 freezable_schedule();
1923 } else {
1924 /*
1925 * By the time we got the lock, our tracer went away.
1926 * Don't drop the lock yet, another tracer may come.
1927 *
1928 * If @gstop_done, the ptracer went away between group stop
1929 * completion and here. During detach, it would have set
1930 * JOBCTL_STOP_PENDING on us and we'll re-enter
1931 * TASK_STOPPED in do_signal_stop() on return, so notifying
1932 * the real parent of the group stop completion is enough.
1933 */
1934 if (gstop_done)
1935 do_notify_parent_cldstop(current, false, why);
1936
1937 /* tasklist protects us from ptrace_freeze_traced() */
1938 __set_current_state(TASK_RUNNING);
1939 if (clear_code)
1940 current->exit_code = 0;
1941 read_unlock(&tasklist_lock);
1942 }
1943
1944 /*
1945 * We are back. Now reacquire the siglock before touching
1946 * last_siginfo, so that we are sure to have synchronized with
1947 * any signal-sending on another CPU that wants to examine it.
1948 */
1949 spin_lock_irq(¤t->sighand->siglock);
1950 current->last_siginfo = NULL;
1951
1952 /* LISTENING can be set only during STOP traps, clear it */
1953 current->jobctl &= ~JOBCTL_LISTENING;
1954
1955 /*
1956 * Queued signals ignored us while we were stopped for tracing.
1957 * So check for any that we should take before resuming user mode.
1958 * This sets TIF_SIGPENDING, but never clears it.
1959 */
1960 recalc_sigpending_tsk(current);
1961}
1962
1963static void ptrace_do_notify(int signr, int exit_code, int why)
1964{
1965 siginfo_t info;
1966
1967 memset(&info, 0, sizeof info);
1968 info.si_signo = signr;
1969 info.si_code = exit_code;
1970 info.si_pid = task_pid_vnr(current);
1971 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1972
1973 /* Let the debugger run. */
1974 ptrace_stop(exit_code, why, 1, &info);
1975}
1976
1977void ptrace_notify(int exit_code)
1978{
1979 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1980 if (unlikely(current->task_works))
1981 task_work_run();
1982
1983 spin_lock_irq(¤t->sighand->siglock);
1984 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1985 spin_unlock_irq(¤t->sighand->siglock);
1986}
1987
1988/**
1989 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1990 * @signr: signr causing group stop if initiating
1991 *
1992 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1993 * and participate in it. If already set, participate in the existing
1994 * group stop. If participated in a group stop (and thus slept), %true is
1995 * returned with siglock released.
1996 *
1997 * If ptraced, this function doesn't handle stop itself. Instead,
1998 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1999 * untouched. The caller must ensure that INTERRUPT trap handling takes
2000 * places afterwards.
2001 *
2002 * CONTEXT:
2003 * Must be called with @current->sighand->siglock held, which is released
2004 * on %true return.
2005 *
2006 * RETURNS:
2007 * %false if group stop is already cancelled or ptrace trap is scheduled.
2008 * %true if participated in group stop.
2009 */
2010static bool do_signal_stop(int signr)
2011 __releases(¤t->sighand->siglock)
2012{
2013 struct signal_struct *sig = current->signal;
2014
2015 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2016 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2017 struct task_struct *t;
2018
2019 /* signr will be recorded in task->jobctl for retries */
2020 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2021
2022 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2023 unlikely(signal_group_exit(sig)))
2024 return false;
2025 /*
2026 * There is no group stop already in progress. We must
2027 * initiate one now.
2028 *
2029 * While ptraced, a task may be resumed while group stop is
2030 * still in effect and then receive a stop signal and
2031 * initiate another group stop. This deviates from the
2032 * usual behavior as two consecutive stop signals can't
2033 * cause two group stops when !ptraced. That is why we
2034 * also check !task_is_stopped(t) below.
2035 *
2036 * The condition can be distinguished by testing whether
2037 * SIGNAL_STOP_STOPPED is already set. Don't generate
2038 * group_exit_code in such case.
2039 *
2040 * This is not necessary for SIGNAL_STOP_CONTINUED because
2041 * an intervening stop signal is required to cause two
2042 * continued events regardless of ptrace.
2043 */
2044 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2045 sig->group_exit_code = signr;
2046
2047 sig->group_stop_count = 0;
2048
2049 if (task_set_jobctl_pending(current, signr | gstop))
2050 sig->group_stop_count++;
2051
2052 t = current;
2053 while_each_thread(current, t) {
2054 /*
2055 * Setting state to TASK_STOPPED for a group
2056 * stop is always done with the siglock held,
2057 * so this check has no races.
2058 */
2059 if (!task_is_stopped(t) &&
2060 task_set_jobctl_pending(t, signr | gstop)) {
2061 sig->group_stop_count++;
2062 if (likely(!(t->ptrace & PT_SEIZED)))
2063 signal_wake_up(t, 0);
2064 else
2065 ptrace_trap_notify(t);
2066 }
2067 }
2068 }
2069
2070 if (likely(!current->ptrace)) {
2071 int notify = 0;
2072
2073 /*
2074 * If there are no other threads in the group, or if there
2075 * is a group stop in progress and we are the last to stop,
2076 * report to the parent.
2077 */
2078 if (task_participate_group_stop(current))
2079 notify = CLD_STOPPED;
2080
2081 __set_current_state(TASK_STOPPED);
2082 spin_unlock_irq(¤t->sighand->siglock);
2083
2084 /*
2085 * Notify the parent of the group stop completion. Because
2086 * we're not holding either the siglock or tasklist_lock
2087 * here, ptracer may attach inbetween; however, this is for
2088 * group stop and should always be delivered to the real
2089 * parent of the group leader. The new ptracer will get
2090 * its notification when this task transitions into
2091 * TASK_TRACED.
2092 */
2093 if (notify) {
2094 read_lock(&tasklist_lock);
2095 do_notify_parent_cldstop(current, false, notify);
2096 read_unlock(&tasklist_lock);
2097 }
2098
2099 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2100 freezable_schedule();
2101 return true;
2102 } else {
2103 /*
2104 * While ptraced, group stop is handled by STOP trap.
2105 * Schedule it and let the caller deal with it.
2106 */
2107 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2108 return false;
2109 }
2110}
2111
2112/**
2113 * do_jobctl_trap - take care of ptrace jobctl traps
2114 *
2115 * When PT_SEIZED, it's used for both group stop and explicit
2116 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2117 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2118 * the stop signal; otherwise, %SIGTRAP.
2119 *
2120 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2121 * number as exit_code and no siginfo.
2122 *
2123 * CONTEXT:
2124 * Must be called with @current->sighand->siglock held, which may be
2125 * released and re-acquired before returning with intervening sleep.
2126 */
2127static void do_jobctl_trap(void)
2128{
2129 struct signal_struct *signal = current->signal;
2130 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2131
2132 if (current->ptrace & PT_SEIZED) {
2133 if (!signal->group_stop_count &&
2134 !(signal->flags & SIGNAL_STOP_STOPPED))
2135 signr = SIGTRAP;
2136 WARN_ON_ONCE(!signr);
2137 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2138 CLD_STOPPED);
2139 } else {
2140 WARN_ON_ONCE(!signr);
2141 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2142 current->exit_code = 0;
2143 }
2144}
2145
2146static int ptrace_signal(int signr, siginfo_t *info)
2147{
2148 ptrace_signal_deliver();
2149 /*
2150 * We do not check sig_kernel_stop(signr) but set this marker
2151 * unconditionally because we do not know whether debugger will
2152 * change signr. This flag has no meaning unless we are going
2153 * to stop after return from ptrace_stop(). In this case it will
2154 * be checked in do_signal_stop(), we should only stop if it was
2155 * not cleared by SIGCONT while we were sleeping. See also the
2156 * comment in dequeue_signal().
2157 */
2158 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2159 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2160
2161 /* We're back. Did the debugger cancel the sig? */
2162 signr = current->exit_code;
2163 if (signr == 0)
2164 return signr;
2165
2166 current->exit_code = 0;
2167
2168 /*
2169 * Update the siginfo structure if the signal has
2170 * changed. If the debugger wanted something
2171 * specific in the siginfo structure then it should
2172 * have updated *info via PTRACE_SETSIGINFO.
2173 */
2174 if (signr != info->si_signo) {
2175 info->si_signo = signr;
2176 info->si_errno = 0;
2177 info->si_code = SI_USER;
2178 rcu_read_lock();
2179 info->si_pid = task_pid_vnr(current->parent);
2180 info->si_uid = from_kuid_munged(current_user_ns(),
2181 task_uid(current->parent));
2182 rcu_read_unlock();
2183 }
2184
2185 /* If the (new) signal is now blocked, requeue it. */
2186 if (sigismember(¤t->blocked, signr)) {
2187 specific_send_sig_info(signr, info, current);
2188 signr = 0;
2189 }
2190
2191 return signr;
2192}
2193
2194int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2195 struct pt_regs *regs, void *cookie)
2196{
2197 struct sighand_struct *sighand = current->sighand;
2198 struct signal_struct *signal = current->signal;
2199 int signr;
2200
2201 if (unlikely(current->task_works))
2202 task_work_run();
2203
2204 if (unlikely(uprobe_deny_signal()))
2205 return 0;
2206
2207 /*
2208 * Do this once, we can't return to user-mode if freezing() == T.
2209 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2210 * thus do not need another check after return.
2211 */
2212 try_to_freeze();
2213
2214relock:
2215 spin_lock_irq(&sighand->siglock);
2216 /*
2217 * Every stopped thread goes here after wakeup. Check to see if
2218 * we should notify the parent, prepare_signal(SIGCONT) encodes
2219 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2220 */
2221 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2222 int why;
2223
2224 if (signal->flags & SIGNAL_CLD_CONTINUED)
2225 why = CLD_CONTINUED;
2226 else
2227 why = CLD_STOPPED;
2228
2229 signal->flags &= ~SIGNAL_CLD_MASK;
2230
2231 spin_unlock_irq(&sighand->siglock);
2232
2233 /*
2234 * Notify the parent that we're continuing. This event is
2235 * always per-process and doesn't make whole lot of sense
2236 * for ptracers, who shouldn't consume the state via
2237 * wait(2) either, but, for backward compatibility, notify
2238 * the ptracer of the group leader too unless it's gonna be
2239 * a duplicate.
2240 */
2241 read_lock(&tasklist_lock);
2242 do_notify_parent_cldstop(current, false, why);
2243
2244 if (ptrace_reparented(current->group_leader))
2245 do_notify_parent_cldstop(current->group_leader,
2246 true, why);
2247 read_unlock(&tasklist_lock);
2248
2249 goto relock;
2250 }
2251
2252 for (;;) {
2253 struct k_sigaction *ka;
2254
2255 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2256 do_signal_stop(0))
2257 goto relock;
2258
2259 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2260 do_jobctl_trap();
2261 spin_unlock_irq(&sighand->siglock);
2262 goto relock;
2263 }
2264
2265 signr = dequeue_signal(current, ¤t->blocked, info);
2266
2267 if (!signr)
2268 break; /* will return 0 */
2269
2270 if (unlikely(current->ptrace) && signr != SIGKILL) {
2271 signr = ptrace_signal(signr, info);
2272 if (!signr)
2273 continue;
2274 }
2275
2276 ka = &sighand->action[signr-1];
2277
2278 /* Trace actually delivered signals. */
2279 trace_signal_deliver(signr, info, ka);
2280
2281 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2282 continue;
2283 if (ka->sa.sa_handler != SIG_DFL) {
2284 /* Run the handler. */
2285 *return_ka = *ka;
2286
2287 if (ka->sa.sa_flags & SA_ONESHOT)
2288 ka->sa.sa_handler = SIG_DFL;
2289
2290 break; /* will return non-zero "signr" value */
2291 }
2292
2293 /*
2294 * Now we are doing the default action for this signal.
2295 */
2296 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2297 continue;
2298
2299 /*
2300 * Global init gets no signals it doesn't want.
2301 * Container-init gets no signals it doesn't want from same
2302 * container.
2303 *
2304 * Note that if global/container-init sees a sig_kernel_only()
2305 * signal here, the signal must have been generated internally
2306 * or must have come from an ancestor namespace. In either
2307 * case, the signal cannot be dropped.
2308 */
2309 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2310 !sig_kernel_only(signr))
2311 continue;
2312
2313 if (sig_kernel_stop(signr)) {
2314 /*
2315 * The default action is to stop all threads in
2316 * the thread group. The job control signals
2317 * do nothing in an orphaned pgrp, but SIGSTOP
2318 * always works. Note that siglock needs to be
2319 * dropped during the call to is_orphaned_pgrp()
2320 * because of lock ordering with tasklist_lock.
2321 * This allows an intervening SIGCONT to be posted.
2322 * We need to check for that and bail out if necessary.
2323 */
2324 if (signr != SIGSTOP) {
2325 spin_unlock_irq(&sighand->siglock);
2326
2327 /* signals can be posted during this window */
2328
2329 if (is_current_pgrp_orphaned())
2330 goto relock;
2331
2332 spin_lock_irq(&sighand->siglock);
2333 }
2334
2335 if (likely(do_signal_stop(info->si_signo))) {
2336 /* It released the siglock. */
2337 goto relock;
2338 }
2339
2340 /*
2341 * We didn't actually stop, due to a race
2342 * with SIGCONT or something like that.
2343 */
2344 continue;
2345 }
2346
2347 spin_unlock_irq(&sighand->siglock);
2348
2349 /*
2350 * Anything else is fatal, maybe with a core dump.
2351 */
2352 current->flags |= PF_SIGNALED;
2353
2354 if (sig_kernel_coredump(signr)) {
2355 if (print_fatal_signals)
2356 print_fatal_signal(info->si_signo);
2357 proc_coredump_connector(current);
2358 /*
2359 * If it was able to dump core, this kills all
2360 * other threads in the group and synchronizes with
2361 * their demise. If we lost the race with another
2362 * thread getting here, it set group_exit_code
2363 * first and our do_group_exit call below will use
2364 * that value and ignore the one we pass it.
2365 */
2366 do_coredump(info);
2367 }
2368
2369 /*
2370 * Death signals, no core dump.
2371 */
2372 do_group_exit(info->si_signo);
2373 /* NOTREACHED */
2374 }
2375 spin_unlock_irq(&sighand->siglock);
2376 return signr;
2377}
2378
2379/**
2380 * signal_delivered -
2381 * @sig: number of signal being delivered
2382 * @info: siginfo_t of signal being delivered
2383 * @ka: sigaction setting that chose the handler
2384 * @regs: user register state
2385 * @stepping: nonzero if debugger single-step or block-step in use
2386 *
2387 * This function should be called when a signal has successfully been
2388 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2389 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2390 * is set in @ka->sa.sa_flags. Tracing is notified.
2391 */
2392void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2393 struct pt_regs *regs, int stepping)
2394{
2395 sigset_t blocked;
2396
2397 /* A signal was successfully delivered, and the
2398 saved sigmask was stored on the signal frame,
2399 and will be restored by sigreturn. So we can
2400 simply clear the restore sigmask flag. */
2401 clear_restore_sigmask();
2402
2403 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2404 if (!(ka->sa.sa_flags & SA_NODEFER))
2405 sigaddset(&blocked, sig);
2406 set_current_blocked(&blocked);
2407 tracehook_signal_handler(sig, info, ka, regs, stepping);
2408}
2409
2410void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2411{
2412 if (failed)
2413 force_sigsegv(ksig->sig, current);
2414 else
2415 signal_delivered(ksig->sig, &ksig->info, &ksig->ka,
2416 signal_pt_regs(), stepping);
2417}
2418
2419/*
2420 * It could be that complete_signal() picked us to notify about the
2421 * group-wide signal. Other threads should be notified now to take
2422 * the shared signals in @which since we will not.
2423 */
2424static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2425{
2426 sigset_t retarget;
2427 struct task_struct *t;
2428
2429 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2430 if (sigisemptyset(&retarget))
2431 return;
2432
2433 t = tsk;
2434 while_each_thread(tsk, t) {
2435 if (t->flags & PF_EXITING)
2436 continue;
2437
2438 if (!has_pending_signals(&retarget, &t->blocked))
2439 continue;
2440 /* Remove the signals this thread can handle. */
2441 sigandsets(&retarget, &retarget, &t->blocked);
2442
2443 if (!signal_pending(t))
2444 signal_wake_up(t, 0);
2445
2446 if (sigisemptyset(&retarget))
2447 break;
2448 }
2449}
2450
2451void exit_signals(struct task_struct *tsk)
2452{
2453 int group_stop = 0;
2454 sigset_t unblocked;
2455
2456 /*
2457 * @tsk is about to have PF_EXITING set - lock out users which
2458 * expect stable threadgroup.
2459 */
2460 threadgroup_change_begin(tsk);
2461
2462 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2463 tsk->flags |= PF_EXITING;
2464 threadgroup_change_end(tsk);
2465 return;
2466 }
2467
2468 spin_lock_irq(&tsk->sighand->siglock);
2469 /*
2470 * From now this task is not visible for group-wide signals,
2471 * see wants_signal(), do_signal_stop().
2472 */
2473 tsk->flags |= PF_EXITING;
2474
2475 threadgroup_change_end(tsk);
2476
2477 if (!signal_pending(tsk))
2478 goto out;
2479
2480 unblocked = tsk->blocked;
2481 signotset(&unblocked);
2482 retarget_shared_pending(tsk, &unblocked);
2483
2484 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2485 task_participate_group_stop(tsk))
2486 group_stop = CLD_STOPPED;
2487out:
2488 spin_unlock_irq(&tsk->sighand->siglock);
2489
2490 /*
2491 * If group stop has completed, deliver the notification. This
2492 * should always go to the real parent of the group leader.
2493 */
2494 if (unlikely(group_stop)) {
2495 read_lock(&tasklist_lock);
2496 do_notify_parent_cldstop(tsk, false, group_stop);
2497 read_unlock(&tasklist_lock);
2498 }
2499}
2500
2501EXPORT_SYMBOL(recalc_sigpending);
2502EXPORT_SYMBOL_GPL(dequeue_signal);
2503EXPORT_SYMBOL(flush_signals);
2504EXPORT_SYMBOL(force_sig);
2505EXPORT_SYMBOL(send_sig);
2506EXPORT_SYMBOL(send_sig_info);
2507EXPORT_SYMBOL(sigprocmask);
2508EXPORT_SYMBOL(block_all_signals);
2509EXPORT_SYMBOL(unblock_all_signals);
2510
2511
2512/*
2513 * System call entry points.
2514 */
2515
2516/**
2517 * sys_restart_syscall - restart a system call
2518 */
2519SYSCALL_DEFINE0(restart_syscall)
2520{
2521 struct restart_block *restart = ¤t_thread_info()->restart_block;
2522 return restart->fn(restart);
2523}
2524
2525long do_no_restart_syscall(struct restart_block *param)
2526{
2527 return -EINTR;
2528}
2529
2530static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2531{
2532 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2533 sigset_t newblocked;
2534 /* A set of now blocked but previously unblocked signals. */
2535 sigandnsets(&newblocked, newset, ¤t->blocked);
2536 retarget_shared_pending(tsk, &newblocked);
2537 }
2538 tsk->blocked = *newset;
2539 recalc_sigpending();
2540}
2541
2542/**
2543 * set_current_blocked - change current->blocked mask
2544 * @newset: new mask
2545 *
2546 * It is wrong to change ->blocked directly, this helper should be used
2547 * to ensure the process can't miss a shared signal we are going to block.
2548 */
2549void set_current_blocked(sigset_t *newset)
2550{
2551 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2552 __set_current_blocked(newset);
2553}
2554
2555void __set_current_blocked(const sigset_t *newset)
2556{
2557 struct task_struct *tsk = current;
2558
2559 spin_lock_irq(&tsk->sighand->siglock);
2560 __set_task_blocked(tsk, newset);
2561 spin_unlock_irq(&tsk->sighand->siglock);
2562}
2563
2564/*
2565 * This is also useful for kernel threads that want to temporarily
2566 * (or permanently) block certain signals.
2567 *
2568 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2569 * interface happily blocks "unblockable" signals like SIGKILL
2570 * and friends.
2571 */
2572int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2573{
2574 struct task_struct *tsk = current;
2575 sigset_t newset;
2576
2577 /* Lockless, only current can change ->blocked, never from irq */
2578 if (oldset)
2579 *oldset = tsk->blocked;
2580
2581 switch (how) {
2582 case SIG_BLOCK:
2583 sigorsets(&newset, &tsk->blocked, set);
2584 break;
2585 case SIG_UNBLOCK:
2586 sigandnsets(&newset, &tsk->blocked, set);
2587 break;
2588 case SIG_SETMASK:
2589 newset = *set;
2590 break;
2591 default:
2592 return -EINVAL;
2593 }
2594
2595 __set_current_blocked(&newset);
2596 return 0;
2597}
2598
2599/**
2600 * sys_rt_sigprocmask - change the list of currently blocked signals
2601 * @how: whether to add, remove, or set signals
2602 * @nset: stores pending signals
2603 * @oset: previous value of signal mask if non-null
2604 * @sigsetsize: size of sigset_t type
2605 */
2606SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2607 sigset_t __user *, oset, size_t, sigsetsize)
2608{
2609 sigset_t old_set, new_set;
2610 int error;
2611
2612 /* XXX: Don't preclude handling different sized sigset_t's. */
2613 if (sigsetsize != sizeof(sigset_t))
2614 return -EINVAL;
2615
2616 old_set = current->blocked;
2617
2618 if (nset) {
2619 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2620 return -EFAULT;
2621 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2622
2623 error = sigprocmask(how, &new_set, NULL);
2624 if (error)
2625 return error;
2626 }
2627
2628 if (oset) {
2629 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2630 return -EFAULT;
2631 }
2632
2633 return 0;
2634}
2635
2636#ifdef CONFIG_COMPAT
2637COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2638 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2639{
2640#ifdef __BIG_ENDIAN
2641 sigset_t old_set = current->blocked;
2642
2643 /* XXX: Don't preclude handling different sized sigset_t's. */
2644 if (sigsetsize != sizeof(sigset_t))
2645 return -EINVAL;
2646
2647 if (nset) {
2648 compat_sigset_t new32;
2649 sigset_t new_set;
2650 int error;
2651 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2652 return -EFAULT;
2653
2654 sigset_from_compat(&new_set, &new32);
2655 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2656
2657 error = sigprocmask(how, &new_set, NULL);
2658 if (error)
2659 return error;
2660 }
2661 if (oset) {
2662 compat_sigset_t old32;
2663 sigset_to_compat(&old32, &old_set);
2664 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2665 return -EFAULT;
2666 }
2667 return 0;
2668#else
2669 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2670 (sigset_t __user *)oset, sigsetsize);
2671#endif
2672}
2673#endif
2674
2675static int do_sigpending(void *set, unsigned long sigsetsize)
2676{
2677 if (sigsetsize > sizeof(sigset_t))
2678 return -EINVAL;
2679
2680 spin_lock_irq(¤t->sighand->siglock);
2681 sigorsets(set, ¤t->pending.signal,
2682 ¤t->signal->shared_pending.signal);
2683 spin_unlock_irq(¤t->sighand->siglock);
2684
2685 /* Outside the lock because only this thread touches it. */
2686 sigandsets(set, ¤t->blocked, set);
2687 return 0;
2688}
2689
2690/**
2691 * sys_rt_sigpending - examine a pending signal that has been raised
2692 * while blocked
2693 * @uset: stores pending signals
2694 * @sigsetsize: size of sigset_t type or larger
2695 */
2696SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2697{
2698 sigset_t set;
2699 int err = do_sigpending(&set, sigsetsize);
2700 if (!err && copy_to_user(uset, &set, sigsetsize))
2701 err = -EFAULT;
2702 return err;
2703}
2704
2705#ifdef CONFIG_COMPAT
2706COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2707 compat_size_t, sigsetsize)
2708{
2709#ifdef __BIG_ENDIAN
2710 sigset_t set;
2711 int err = do_sigpending(&set, sigsetsize);
2712 if (!err) {
2713 compat_sigset_t set32;
2714 sigset_to_compat(&set32, &set);
2715 /* we can get here only if sigsetsize <= sizeof(set) */
2716 if (copy_to_user(uset, &set32, sigsetsize))
2717 err = -EFAULT;
2718 }
2719 return err;
2720#else
2721 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2722#endif
2723}
2724#endif
2725
2726#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2727
2728int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2729{
2730 int err;
2731
2732 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2733 return -EFAULT;
2734 if (from->si_code < 0)
2735 return __copy_to_user(to, from, sizeof(siginfo_t))
2736 ? -EFAULT : 0;
2737 /*
2738 * If you change siginfo_t structure, please be sure
2739 * this code is fixed accordingly.
2740 * Please remember to update the signalfd_copyinfo() function
2741 * inside fs/signalfd.c too, in case siginfo_t changes.
2742 * It should never copy any pad contained in the structure
2743 * to avoid security leaks, but must copy the generic
2744 * 3 ints plus the relevant union member.
2745 */
2746 err = __put_user(from->si_signo, &to->si_signo);
2747 err |= __put_user(from->si_errno, &to->si_errno);
2748 err |= __put_user((short)from->si_code, &to->si_code);
2749 switch (from->si_code & __SI_MASK) {
2750 case __SI_KILL:
2751 err |= __put_user(from->si_pid, &to->si_pid);
2752 err |= __put_user(from->si_uid, &to->si_uid);
2753 break;
2754 case __SI_TIMER:
2755 err |= __put_user(from->si_tid, &to->si_tid);
2756 err |= __put_user(from->si_overrun, &to->si_overrun);
2757 err |= __put_user(from->si_ptr, &to->si_ptr);
2758 break;
2759 case __SI_POLL:
2760 err |= __put_user(from->si_band, &to->si_band);
2761 err |= __put_user(from->si_fd, &to->si_fd);
2762 break;
2763 case __SI_FAULT:
2764 err |= __put_user(from->si_addr, &to->si_addr);
2765#ifdef __ARCH_SI_TRAPNO
2766 err |= __put_user(from->si_trapno, &to->si_trapno);
2767#endif
2768#ifdef BUS_MCEERR_AO
2769 /*
2770 * Other callers might not initialize the si_lsb field,
2771 * so check explicitly for the right codes here.
2772 */
2773 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2774 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2775#endif
2776 break;
2777 case __SI_CHLD:
2778 err |= __put_user(from->si_pid, &to->si_pid);
2779 err |= __put_user(from->si_uid, &to->si_uid);
2780 err |= __put_user(from->si_status, &to->si_status);
2781 err |= __put_user(from->si_utime, &to->si_utime);
2782 err |= __put_user(from->si_stime, &to->si_stime);
2783 break;
2784 case __SI_RT: /* This is not generated by the kernel as of now. */
2785 case __SI_MESGQ: /* But this is */
2786 err |= __put_user(from->si_pid, &to->si_pid);
2787 err |= __put_user(from->si_uid, &to->si_uid);
2788 err |= __put_user(from->si_ptr, &to->si_ptr);
2789 break;
2790#ifdef __ARCH_SIGSYS
2791 case __SI_SYS:
2792 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2793 err |= __put_user(from->si_syscall, &to->si_syscall);
2794 err |= __put_user(from->si_arch, &to->si_arch);
2795 break;
2796#endif
2797 default: /* this is just in case for now ... */
2798 err |= __put_user(from->si_pid, &to->si_pid);
2799 err |= __put_user(from->si_uid, &to->si_uid);
2800 break;
2801 }
2802 return err;
2803}
2804
2805#endif
2806
2807/**
2808 * do_sigtimedwait - wait for queued signals specified in @which
2809 * @which: queued signals to wait for
2810 * @info: if non-null, the signal's siginfo is returned here
2811 * @ts: upper bound on process time suspension
2812 */
2813int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2814 const struct timespec *ts)
2815{
2816 struct task_struct *tsk = current;
2817 long timeout = MAX_SCHEDULE_TIMEOUT;
2818 sigset_t mask = *which;
2819 int sig;
2820
2821 if (ts) {
2822 if (!timespec_valid(ts))
2823 return -EINVAL;
2824 timeout = timespec_to_jiffies(ts);
2825 /*
2826 * We can be close to the next tick, add another one
2827 * to ensure we will wait at least the time asked for.
2828 */
2829 if (ts->tv_sec || ts->tv_nsec)
2830 timeout++;
2831 }
2832
2833 /*
2834 * Invert the set of allowed signals to get those we want to block.
2835 */
2836 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2837 signotset(&mask);
2838
2839 spin_lock_irq(&tsk->sighand->siglock);
2840 sig = dequeue_signal(tsk, &mask, info);
2841 if (!sig && timeout) {
2842 /*
2843 * None ready, temporarily unblock those we're interested
2844 * while we are sleeping in so that we'll be awakened when
2845 * they arrive. Unblocking is always fine, we can avoid
2846 * set_current_blocked().
2847 */
2848 tsk->real_blocked = tsk->blocked;
2849 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2850 recalc_sigpending();
2851 spin_unlock_irq(&tsk->sighand->siglock);
2852
2853 timeout = freezable_schedule_timeout_interruptible(timeout);
2854
2855 spin_lock_irq(&tsk->sighand->siglock);
2856 __set_task_blocked(tsk, &tsk->real_blocked);
2857 siginitset(&tsk->real_blocked, 0);
2858 sig = dequeue_signal(tsk, &mask, info);
2859 }
2860 spin_unlock_irq(&tsk->sighand->siglock);
2861
2862 if (sig)
2863 return sig;
2864 return timeout ? -EINTR : -EAGAIN;
2865}
2866
2867/**
2868 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2869 * in @uthese
2870 * @uthese: queued signals to wait for
2871 * @uinfo: if non-null, the signal's siginfo is returned here
2872 * @uts: upper bound on process time suspension
2873 * @sigsetsize: size of sigset_t type
2874 */
2875SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2876 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2877 size_t, sigsetsize)
2878{
2879 sigset_t these;
2880 struct timespec ts;
2881 siginfo_t info;
2882 int ret;
2883
2884 /* XXX: Don't preclude handling different sized sigset_t's. */
2885 if (sigsetsize != sizeof(sigset_t))
2886 return -EINVAL;
2887
2888 if (copy_from_user(&these, uthese, sizeof(these)))
2889 return -EFAULT;
2890
2891 if (uts) {
2892 if (copy_from_user(&ts, uts, sizeof(ts)))
2893 return -EFAULT;
2894 }
2895
2896 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2897
2898 if (ret > 0 && uinfo) {
2899 if (copy_siginfo_to_user(uinfo, &info))
2900 ret = -EFAULT;
2901 }
2902
2903 return ret;
2904}
2905
2906/**
2907 * sys_kill - send a signal to a process
2908 * @pid: the PID of the process
2909 * @sig: signal to be sent
2910 */
2911SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2912{
2913 struct siginfo info;
2914
2915 info.si_signo = sig;
2916 info.si_errno = 0;
2917 info.si_code = SI_USER;
2918 info.si_pid = task_tgid_vnr(current);
2919 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2920
2921 return kill_something_info(sig, &info, pid);
2922}
2923
2924static int
2925do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2926{
2927 struct task_struct *p;
2928 int error = -ESRCH;
2929
2930 rcu_read_lock();
2931 p = find_task_by_vpid(pid);
2932 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2933 error = check_kill_permission(sig, info, p);
2934 /*
2935 * The null signal is a permissions and process existence
2936 * probe. No signal is actually delivered.
2937 */
2938 if (!error && sig) {
2939 error = do_send_sig_info(sig, info, p, false);
2940 /*
2941 * If lock_task_sighand() failed we pretend the task
2942 * dies after receiving the signal. The window is tiny,
2943 * and the signal is private anyway.
2944 */
2945 if (unlikely(error == -ESRCH))
2946 error = 0;
2947 }
2948 }
2949 rcu_read_unlock();
2950
2951 return error;
2952}
2953
2954static int do_tkill(pid_t tgid, pid_t pid, int sig)
2955{
2956 struct siginfo info = {};
2957
2958 info.si_signo = sig;
2959 info.si_errno = 0;
2960 info.si_code = SI_TKILL;
2961 info.si_pid = task_tgid_vnr(current);
2962 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2963
2964 return do_send_specific(tgid, pid, sig, &info);
2965}
2966
2967/**
2968 * sys_tgkill - send signal to one specific thread
2969 * @tgid: the thread group ID of the thread
2970 * @pid: the PID of the thread
2971 * @sig: signal to be sent
2972 *
2973 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2974 * exists but it's not belonging to the target process anymore. This
2975 * method solves the problem of threads exiting and PIDs getting reused.
2976 */
2977SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2978{
2979 /* This is only valid for single tasks */
2980 if (pid <= 0 || tgid <= 0)
2981 return -EINVAL;
2982
2983 return do_tkill(tgid, pid, sig);
2984}
2985
2986/**
2987 * sys_tkill - send signal to one specific task
2988 * @pid: the PID of the task
2989 * @sig: signal to be sent
2990 *
2991 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2992 */
2993SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2994{
2995 /* This is only valid for single tasks */
2996 if (pid <= 0)
2997 return -EINVAL;
2998
2999 return do_tkill(0, pid, sig);
3000}
3001
3002static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3003{
3004 /* Not even root can pretend to send signals from the kernel.
3005 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3006 */
3007 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3008 (task_pid_vnr(current) != pid)) {
3009 /* We used to allow any < 0 si_code */
3010 WARN_ON_ONCE(info->si_code < 0);
3011 return -EPERM;
3012 }
3013 info->si_signo = sig;
3014
3015 /* POSIX.1b doesn't mention process groups. */
3016 return kill_proc_info(sig, info, pid);
3017}
3018
3019/**
3020 * sys_rt_sigqueueinfo - send signal information to a signal
3021 * @pid: the PID of the thread
3022 * @sig: signal to be sent
3023 * @uinfo: signal info to be sent
3024 */
3025SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3026 siginfo_t __user *, uinfo)
3027{
3028 siginfo_t info;
3029 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3030 return -EFAULT;
3031 return do_rt_sigqueueinfo(pid, sig, &info);
3032}
3033
3034#ifdef CONFIG_COMPAT
3035COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3036 compat_pid_t, pid,
3037 int, sig,
3038 struct compat_siginfo __user *, uinfo)
3039{
3040 siginfo_t info;
3041 int ret = copy_siginfo_from_user32(&info, uinfo);
3042 if (unlikely(ret))
3043 return ret;
3044 return do_rt_sigqueueinfo(pid, sig, &info);
3045}
3046#endif
3047
3048static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3049{
3050 /* This is only valid for single tasks */
3051 if (pid <= 0 || tgid <= 0)
3052 return -EINVAL;
3053
3054 /* Not even root can pretend to send signals from the kernel.
3055 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3056 */
3057 if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
3058 (task_pid_vnr(current) != pid)) {
3059 /* We used to allow any < 0 si_code */
3060 WARN_ON_ONCE(info->si_code < 0);
3061 return -EPERM;
3062 }
3063 info->si_signo = sig;
3064
3065 return do_send_specific(tgid, pid, sig, info);
3066}
3067
3068SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3069 siginfo_t __user *, uinfo)
3070{
3071 siginfo_t info;
3072
3073 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3074 return -EFAULT;
3075
3076 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3077}
3078
3079#ifdef CONFIG_COMPAT
3080COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3081 compat_pid_t, tgid,
3082 compat_pid_t, pid,
3083 int, sig,
3084 struct compat_siginfo __user *, uinfo)
3085{
3086 siginfo_t info;
3087
3088 if (copy_siginfo_from_user32(&info, uinfo))
3089 return -EFAULT;
3090 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3091}
3092#endif
3093
3094int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3095{
3096 struct task_struct *t = current;
3097 struct k_sigaction *k;
3098 sigset_t mask;
3099
3100 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3101 return -EINVAL;
3102
3103 k = &t->sighand->action[sig-1];
3104
3105 spin_lock_irq(¤t->sighand->siglock);
3106 if (oact)
3107 *oact = *k;
3108
3109 if (act) {
3110 sigdelsetmask(&act->sa.sa_mask,
3111 sigmask(SIGKILL) | sigmask(SIGSTOP));
3112 *k = *act;
3113 /*
3114 * POSIX 3.3.1.3:
3115 * "Setting a signal action to SIG_IGN for a signal that is
3116 * pending shall cause the pending signal to be discarded,
3117 * whether or not it is blocked."
3118 *
3119 * "Setting a signal action to SIG_DFL for a signal that is
3120 * pending and whose default action is to ignore the signal
3121 * (for example, SIGCHLD), shall cause the pending signal to
3122 * be discarded, whether or not it is blocked"
3123 */
3124 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3125 sigemptyset(&mask);
3126 sigaddset(&mask, sig);
3127 rm_from_queue_full(&mask, &t->signal->shared_pending);
3128 do {
3129 rm_from_queue_full(&mask, &t->pending);
3130 } while_each_thread(current, t);
3131 }
3132 }
3133
3134 spin_unlock_irq(¤t->sighand->siglock);
3135 return 0;
3136}
3137
3138static int
3139do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3140{
3141 stack_t oss;
3142 int error;
3143
3144 oss.ss_sp = (void __user *) current->sas_ss_sp;
3145 oss.ss_size = current->sas_ss_size;
3146 oss.ss_flags = sas_ss_flags(sp);
3147
3148 if (uss) {
3149 void __user *ss_sp;
3150 size_t ss_size;
3151 int ss_flags;
3152
3153 error = -EFAULT;
3154 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3155 goto out;
3156 error = __get_user(ss_sp, &uss->ss_sp) |
3157 __get_user(ss_flags, &uss->ss_flags) |
3158 __get_user(ss_size, &uss->ss_size);
3159 if (error)
3160 goto out;
3161
3162 error = -EPERM;
3163 if (on_sig_stack(sp))
3164 goto out;
3165
3166 error = -EINVAL;
3167 /*
3168 * Note - this code used to test ss_flags incorrectly:
3169 * old code may have been written using ss_flags==0
3170 * to mean ss_flags==SS_ONSTACK (as this was the only
3171 * way that worked) - this fix preserves that older
3172 * mechanism.
3173 */
3174 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3175 goto out;
3176
3177 if (ss_flags == SS_DISABLE) {
3178 ss_size = 0;
3179 ss_sp = NULL;
3180 } else {
3181 error = -ENOMEM;
3182 if (ss_size < MINSIGSTKSZ)
3183 goto out;
3184 }
3185
3186 current->sas_ss_sp = (unsigned long) ss_sp;
3187 current->sas_ss_size = ss_size;
3188 }
3189
3190 error = 0;
3191 if (uoss) {
3192 error = -EFAULT;
3193 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3194 goto out;
3195 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3196 __put_user(oss.ss_size, &uoss->ss_size) |
3197 __put_user(oss.ss_flags, &uoss->ss_flags);
3198 }
3199
3200out:
3201 return error;
3202}
3203SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3204{
3205 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3206}
3207
3208int restore_altstack(const stack_t __user *uss)
3209{
3210 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3211 /* squash all but EFAULT for now */
3212 return err == -EFAULT ? err : 0;
3213}
3214
3215int __save_altstack(stack_t __user *uss, unsigned long sp)
3216{
3217 struct task_struct *t = current;
3218 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3219 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3220 __put_user(t->sas_ss_size, &uss->ss_size);
3221}
3222
3223#ifdef CONFIG_COMPAT
3224COMPAT_SYSCALL_DEFINE2(sigaltstack,
3225 const compat_stack_t __user *, uss_ptr,
3226 compat_stack_t __user *, uoss_ptr)
3227{
3228 stack_t uss, uoss;
3229 int ret;
3230 mm_segment_t seg;
3231
3232 if (uss_ptr) {
3233 compat_stack_t uss32;
3234
3235 memset(&uss, 0, sizeof(stack_t));
3236 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3237 return -EFAULT;
3238 uss.ss_sp = compat_ptr(uss32.ss_sp);
3239 uss.ss_flags = uss32.ss_flags;
3240 uss.ss_size = uss32.ss_size;
3241 }
3242 seg = get_fs();
3243 set_fs(KERNEL_DS);
3244 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3245 (stack_t __force __user *) &uoss,
3246 compat_user_stack_pointer());
3247 set_fs(seg);
3248 if (ret >= 0 && uoss_ptr) {
3249 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3250 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3251 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3252 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3253 ret = -EFAULT;
3254 }
3255 return ret;
3256}
3257
3258int compat_restore_altstack(const compat_stack_t __user *uss)
3259{
3260 int err = compat_sys_sigaltstack(uss, NULL);
3261 /* squash all but -EFAULT for now */
3262 return err == -EFAULT ? err : 0;
3263}
3264
3265int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3266{
3267 struct task_struct *t = current;
3268 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3269 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3270 __put_user(t->sas_ss_size, &uss->ss_size);
3271}
3272#endif
3273
3274#ifdef __ARCH_WANT_SYS_SIGPENDING
3275
3276/**
3277 * sys_sigpending - examine pending signals
3278 * @set: where mask of pending signal is returned
3279 */
3280SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3281{
3282 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3283}
3284
3285#endif
3286
3287#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3288/**
3289 * sys_sigprocmask - examine and change blocked signals
3290 * @how: whether to add, remove, or set signals
3291 * @nset: signals to add or remove (if non-null)
3292 * @oset: previous value of signal mask if non-null
3293 *
3294 * Some platforms have their own version with special arguments;
3295 * others support only sys_rt_sigprocmask.
3296 */
3297
3298SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3299 old_sigset_t __user *, oset)
3300{
3301 old_sigset_t old_set, new_set;
3302 sigset_t new_blocked;
3303
3304 old_set = current->blocked.sig[0];
3305
3306 if (nset) {
3307 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3308 return -EFAULT;
3309
3310 new_blocked = current->blocked;
3311
3312 switch (how) {
3313 case SIG_BLOCK:
3314 sigaddsetmask(&new_blocked, new_set);
3315 break;
3316 case SIG_UNBLOCK:
3317 sigdelsetmask(&new_blocked, new_set);
3318 break;
3319 case SIG_SETMASK:
3320 new_blocked.sig[0] = new_set;
3321 break;
3322 default:
3323 return -EINVAL;
3324 }
3325
3326 set_current_blocked(&new_blocked);
3327 }
3328
3329 if (oset) {
3330 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3331 return -EFAULT;
3332 }
3333
3334 return 0;
3335}
3336#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3337
3338#ifndef CONFIG_ODD_RT_SIGACTION
3339/**
3340 * sys_rt_sigaction - alter an action taken by a process
3341 * @sig: signal to be sent
3342 * @act: new sigaction
3343 * @oact: used to save the previous sigaction
3344 * @sigsetsize: size of sigset_t type
3345 */
3346SYSCALL_DEFINE4(rt_sigaction, int, sig,
3347 const struct sigaction __user *, act,
3348 struct sigaction __user *, oact,
3349 size_t, sigsetsize)
3350{
3351 struct k_sigaction new_sa, old_sa;
3352 int ret = -EINVAL;
3353
3354 /* XXX: Don't preclude handling different sized sigset_t's. */
3355 if (sigsetsize != sizeof(sigset_t))
3356 goto out;
3357
3358 if (act) {
3359 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3360 return -EFAULT;
3361 }
3362
3363 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3364
3365 if (!ret && oact) {
3366 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3367 return -EFAULT;
3368 }
3369out:
3370 return ret;
3371}
3372#ifdef CONFIG_COMPAT
3373COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3374 const struct compat_sigaction __user *, act,
3375 struct compat_sigaction __user *, oact,
3376 compat_size_t, sigsetsize)
3377{
3378 struct k_sigaction new_ka, old_ka;
3379 compat_sigset_t mask;
3380#ifdef __ARCH_HAS_SA_RESTORER
3381 compat_uptr_t restorer;
3382#endif
3383 int ret;
3384
3385 /* XXX: Don't preclude handling different sized sigset_t's. */
3386 if (sigsetsize != sizeof(compat_sigset_t))
3387 return -EINVAL;
3388
3389 if (act) {
3390 compat_uptr_t handler;
3391 ret = get_user(handler, &act->sa_handler);
3392 new_ka.sa.sa_handler = compat_ptr(handler);
3393#ifdef __ARCH_HAS_SA_RESTORER
3394 ret |= get_user(restorer, &act->sa_restorer);
3395 new_ka.sa.sa_restorer = compat_ptr(restorer);
3396#endif
3397 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3398 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3399 if (ret)
3400 return -EFAULT;
3401 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3402 }
3403
3404 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3405 if (!ret && oact) {
3406 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3407 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3408 &oact->sa_handler);
3409 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3410 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3411#ifdef __ARCH_HAS_SA_RESTORER
3412 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3413 &oact->sa_restorer);
3414#endif
3415 }
3416 return ret;
3417}
3418#endif
3419#endif /* !CONFIG_ODD_RT_SIGACTION */
3420
3421#ifdef CONFIG_OLD_SIGACTION
3422SYSCALL_DEFINE3(sigaction, int, sig,
3423 const struct old_sigaction __user *, act,
3424 struct old_sigaction __user *, oact)
3425{
3426 struct k_sigaction new_ka, old_ka;
3427 int ret;
3428
3429 if (act) {
3430 old_sigset_t mask;
3431 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3432 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3433 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3434 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3435 __get_user(mask, &act->sa_mask))
3436 return -EFAULT;
3437#ifdef __ARCH_HAS_KA_RESTORER
3438 new_ka.ka_restorer = NULL;
3439#endif
3440 siginitset(&new_ka.sa.sa_mask, mask);
3441 }
3442
3443 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3444
3445 if (!ret && oact) {
3446 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3447 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3448 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3449 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3450 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3451 return -EFAULT;
3452 }
3453
3454 return ret;
3455}
3456#endif
3457#ifdef CONFIG_COMPAT_OLD_SIGACTION
3458COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3459 const struct compat_old_sigaction __user *, act,
3460 struct compat_old_sigaction __user *, oact)
3461{
3462 struct k_sigaction new_ka, old_ka;
3463 int ret;
3464 compat_old_sigset_t mask;
3465 compat_uptr_t handler, restorer;
3466
3467 if (act) {
3468 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3469 __get_user(handler, &act->sa_handler) ||
3470 __get_user(restorer, &act->sa_restorer) ||
3471 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3472 __get_user(mask, &act->sa_mask))
3473 return -EFAULT;
3474
3475#ifdef __ARCH_HAS_KA_RESTORER
3476 new_ka.ka_restorer = NULL;
3477#endif
3478 new_ka.sa.sa_handler = compat_ptr(handler);
3479 new_ka.sa.sa_restorer = compat_ptr(restorer);
3480 siginitset(&new_ka.sa.sa_mask, mask);
3481 }
3482
3483 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3484
3485 if (!ret && oact) {
3486 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3487 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3488 &oact->sa_handler) ||
3489 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3490 &oact->sa_restorer) ||
3491 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3492 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3493 return -EFAULT;
3494 }
3495 return ret;
3496}
3497#endif
3498
3499#ifdef __ARCH_WANT_SYS_SGETMASK
3500
3501/*
3502 * For backwards compatibility. Functionality superseded by sigprocmask.
3503 */
3504SYSCALL_DEFINE0(sgetmask)
3505{
3506 /* SMP safe */
3507 return current->blocked.sig[0];
3508}
3509
3510SYSCALL_DEFINE1(ssetmask, int, newmask)
3511{
3512 int old = current->blocked.sig[0];
3513 sigset_t newset;
3514
3515 siginitset(&newset, newmask);
3516 set_current_blocked(&newset);
3517
3518 return old;
3519}
3520#endif /* __ARCH_WANT_SGETMASK */
3521
3522#ifdef __ARCH_WANT_SYS_SIGNAL
3523/*
3524 * For backwards compatibility. Functionality superseded by sigaction.
3525 */
3526SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3527{
3528 struct k_sigaction new_sa, old_sa;
3529 int ret;
3530
3531 new_sa.sa.sa_handler = handler;
3532 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3533 sigemptyset(&new_sa.sa.sa_mask);
3534
3535 ret = do_sigaction(sig, &new_sa, &old_sa);
3536
3537 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3538}
3539#endif /* __ARCH_WANT_SYS_SIGNAL */
3540
3541#ifdef __ARCH_WANT_SYS_PAUSE
3542
3543SYSCALL_DEFINE0(pause)
3544{
3545 while (!signal_pending(current)) {
3546 current->state = TASK_INTERRUPTIBLE;
3547 schedule();
3548 }
3549 return -ERESTARTNOHAND;
3550}
3551
3552#endif
3553
3554int sigsuspend(sigset_t *set)
3555{
3556 current->saved_sigmask = current->blocked;
3557 set_current_blocked(set);
3558
3559 current->state = TASK_INTERRUPTIBLE;
3560 schedule();
3561 set_restore_sigmask();
3562 return -ERESTARTNOHAND;
3563}
3564
3565/**
3566 * sys_rt_sigsuspend - replace the signal mask for a value with the
3567 * @unewset value until a signal is received
3568 * @unewset: new signal mask value
3569 * @sigsetsize: size of sigset_t type
3570 */
3571SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3572{
3573 sigset_t newset;
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(&newset, unewset, sizeof(newset)))
3580 return -EFAULT;
3581 return sigsuspend(&newset);
3582}
3583
3584#ifdef CONFIG_COMPAT
3585COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3586{
3587#ifdef __BIG_ENDIAN
3588 sigset_t newset;
3589 compat_sigset_t newset32;
3590
3591 /* XXX: Don't preclude handling different sized sigset_t's. */
3592 if (sigsetsize != sizeof(sigset_t))
3593 return -EINVAL;
3594
3595 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3596 return -EFAULT;
3597 sigset_from_compat(&newset, &newset32);
3598 return sigsuspend(&newset);
3599#else
3600 /* on little-endian bitmaps don't care about granularity */
3601 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3602#endif
3603}
3604#endif
3605
3606#ifdef CONFIG_OLD_SIGSUSPEND
3607SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3608{
3609 sigset_t blocked;
3610 siginitset(&blocked, mask);
3611 return sigsuspend(&blocked);
3612}
3613#endif
3614#ifdef CONFIG_OLD_SIGSUSPEND3
3615SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3616{
3617 sigset_t blocked;
3618 siginitset(&blocked, mask);
3619 return sigsuspend(&blocked);
3620}
3621#endif
3622
3623__weak const char *arch_vma_name(struct vm_area_struct *vma)
3624{
3625 return NULL;
3626}
3627
3628void __init signals_init(void)
3629{
3630 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3631}
3632
3633#ifdef CONFIG_KGDB_KDB
3634#include <linux/kdb.h>
3635/*
3636 * kdb_send_sig_info - Allows kdb to send signals without exposing
3637 * signal internals. This function checks if the required locks are
3638 * available before calling the main signal code, to avoid kdb
3639 * deadlocks.
3640 */
3641void
3642kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3643{
3644 static struct task_struct *kdb_prev_t;
3645 int sig, new_t;
3646 if (!spin_trylock(&t->sighand->siglock)) {
3647 kdb_printf("Can't do kill command now.\n"
3648 "The sigmask lock is held somewhere else in "
3649 "kernel, try again later\n");
3650 return;
3651 }
3652 spin_unlock(&t->sighand->siglock);
3653 new_t = kdb_prev_t != t;
3654 kdb_prev_t = t;
3655 if (t->state != TASK_RUNNING && new_t) {
3656 kdb_printf("Process is not RUNNING, sending a signal from "
3657 "kdb risks deadlock\n"
3658 "on the run queue locks. "
3659 "The signal has _not_ been sent.\n"
3660 "Reissue the kill command if you want to risk "
3661 "the deadlock.\n");
3662 return;
3663 }
3664 sig = info->si_signo;
3665 if (send_sig_info(sig, info, t))
3666 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3667 sig, t->pid);
3668 else
3669 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3670}
3671#endif /* CONFIG_KGDB_KDB */