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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 <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 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 sig->flags = 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
430static void __flush_itimer_signals(struct sigpending *pending)
431{
432 sigset_t signal, retain;
433 struct sigqueue *q, *n;
434
435 signal = pending->signal;
436 sigemptyset(&retain);
437
438 list_for_each_entry_safe(q, n, &pending->list, list) {
439 int sig = q->info.si_signo;
440
441 if (likely(q->info.si_code != SI_TIMER)) {
442 sigaddset(&retain, sig);
443 } else {
444 sigdelset(&signal, sig);
445 list_del_init(&q->list);
446 __sigqueue_free(q);
447 }
448 }
449
450 sigorsets(&pending->signal, &signal, &retain);
451}
452
453void flush_itimer_signals(void)
454{
455 struct task_struct *tsk = current;
456 unsigned long flags;
457
458 spin_lock_irqsave(&tsk->sighand->siglock, flags);
459 __flush_itimer_signals(&tsk->pending);
460 __flush_itimer_signals(&tsk->signal->shared_pending);
461 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
462}
463
464void ignore_signals(struct task_struct *t)
465{
466 int i;
467
468 for (i = 0; i < _NSIG; ++i)
469 t->sighand->action[i].sa.sa_handler = SIG_IGN;
470
471 flush_signals(t);
472}
473
474/*
475 * Flush all handlers for a task.
476 */
477
478void
479flush_signal_handlers(struct task_struct *t, int force_default)
480{
481 int i;
482 struct k_sigaction *ka = &t->sighand->action[0];
483 for (i = _NSIG ; i != 0 ; i--) {
484 if (force_default || ka->sa.sa_handler != SIG_IGN)
485 ka->sa.sa_handler = SIG_DFL;
486 ka->sa.sa_flags = 0;
487#ifdef __ARCH_HAS_SA_RESTORER
488 ka->sa.sa_restorer = NULL;
489#endif
490 sigemptyset(&ka->sa.sa_mask);
491 ka++;
492 }
493}
494
495int unhandled_signal(struct task_struct *tsk, int sig)
496{
497 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
498 if (is_global_init(tsk))
499 return 1;
500 if (handler != SIG_IGN && handler != SIG_DFL)
501 return 0;
502 /* if ptraced, let the tracer determine */
503 return !tsk->ptrace;
504}
505
506static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
507{
508 struct sigqueue *q, *first = NULL;
509
510 /*
511 * Collect the siginfo appropriate to this signal. Check if
512 * there is another siginfo for the same signal.
513 */
514 list_for_each_entry(q, &list->list, list) {
515 if (q->info.si_signo == sig) {
516 if (first)
517 goto still_pending;
518 first = q;
519 }
520 }
521
522 sigdelset(&list->signal, sig);
523
524 if (first) {
525still_pending:
526 list_del_init(&first->list);
527 copy_siginfo(info, &first->info);
528 __sigqueue_free(first);
529 } else {
530 /*
531 * Ok, it wasn't in the queue. This must be
532 * a fast-pathed signal or we must have been
533 * out of queue space. So zero out the info.
534 */
535 info->si_signo = sig;
536 info->si_errno = 0;
537 info->si_code = SI_USER;
538 info->si_pid = 0;
539 info->si_uid = 0;
540 }
541}
542
543static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
544 siginfo_t *info)
545{
546 int sig = next_signal(pending, mask);
547
548 if (sig)
549 collect_signal(sig, pending, info);
550 return sig;
551}
552
553/*
554 * Dequeue a signal and return the element to the caller, which is
555 * expected to free it.
556 *
557 * All callers have to hold the siglock.
558 */
559int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
560{
561 int signr;
562
563 /* We only dequeue private signals from ourselves, we don't let
564 * signalfd steal them
565 */
566 signr = __dequeue_signal(&tsk->pending, mask, info);
567 if (!signr) {
568 signr = __dequeue_signal(&tsk->signal->shared_pending,
569 mask, info);
570 /*
571 * itimer signal ?
572 *
573 * itimers are process shared and we restart periodic
574 * itimers in the signal delivery path to prevent DoS
575 * attacks in the high resolution timer case. This is
576 * compliant with the old way of self-restarting
577 * itimers, as the SIGALRM is a legacy signal and only
578 * queued once. Changing the restart behaviour to
579 * restart the timer in the signal dequeue path is
580 * reducing the timer noise on heavy loaded !highres
581 * systems too.
582 */
583 if (unlikely(signr == SIGALRM)) {
584 struct hrtimer *tmr = &tsk->signal->real_timer;
585
586 if (!hrtimer_is_queued(tmr) &&
587 tsk->signal->it_real_incr.tv64 != 0) {
588 hrtimer_forward(tmr, tmr->base->get_time(),
589 tsk->signal->it_real_incr);
590 hrtimer_restart(tmr);
591 }
592 }
593 }
594
595 recalc_sigpending();
596 if (!signr)
597 return 0;
598
599 if (unlikely(sig_kernel_stop(signr))) {
600 /*
601 * Set a marker that we have dequeued a stop signal. Our
602 * caller might release the siglock and then the pending
603 * stop signal it is about to process is no longer in the
604 * pending bitmasks, but must still be cleared by a SIGCONT
605 * (and overruled by a SIGKILL). So those cases clear this
606 * shared flag after we've set it. Note that this flag may
607 * remain set after the signal we return is ignored or
608 * handled. That doesn't matter because its only purpose
609 * is to alert stop-signal processing code when another
610 * processor has come along and cleared the flag.
611 */
612 current->jobctl |= JOBCTL_STOP_DEQUEUED;
613 }
614 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
615 /*
616 * Release the siglock to ensure proper locking order
617 * of timer locks outside of siglocks. Note, we leave
618 * irqs disabled here, since the posix-timers code is
619 * about to disable them again anyway.
620 */
621 spin_unlock(&tsk->sighand->siglock);
622 do_schedule_next_timer(info);
623 spin_lock(&tsk->sighand->siglock);
624 }
625 return signr;
626}
627
628/*
629 * Tell a process that it has a new active signal..
630 *
631 * NOTE! we rely on the previous spin_lock to
632 * lock interrupts for us! We can only be called with
633 * "siglock" held, and the local interrupt must
634 * have been disabled when that got acquired!
635 *
636 * No need to set need_resched since signal event passing
637 * goes through ->blocked
638 */
639void signal_wake_up_state(struct task_struct *t, unsigned int state)
640{
641 set_tsk_thread_flag(t, TIF_SIGPENDING);
642 /*
643 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
644 * case. We don't check t->state here because there is a race with it
645 * executing another processor and just now entering stopped state.
646 * By using wake_up_state, we ensure the process will wake up and
647 * handle its death signal.
648 */
649 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
650 kick_process(t);
651}
652
653/*
654 * Remove signals in mask from the pending set and queue.
655 * Returns 1 if any signals were found.
656 *
657 * All callers must be holding the siglock.
658 */
659static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
660{
661 struct sigqueue *q, *n;
662 sigset_t m;
663
664 sigandsets(&m, mask, &s->signal);
665 if (sigisemptyset(&m))
666 return 0;
667
668 sigandnsets(&s->signal, &s->signal, mask);
669 list_for_each_entry_safe(q, n, &s->list, list) {
670 if (sigismember(mask, q->info.si_signo)) {
671 list_del_init(&q->list);
672 __sigqueue_free(q);
673 }
674 }
675 return 1;
676}
677
678static inline int is_si_special(const struct siginfo *info)
679{
680 return info <= SEND_SIG_FORCED;
681}
682
683static inline bool si_fromuser(const struct siginfo *info)
684{
685 return info == SEND_SIG_NOINFO ||
686 (!is_si_special(info) && SI_FROMUSER(info));
687}
688
689/*
690 * called with RCU read lock from check_kill_permission()
691 */
692static int kill_ok_by_cred(struct task_struct *t)
693{
694 const struct cred *cred = current_cred();
695 const struct cred *tcred = __task_cred(t);
696
697 if (uid_eq(cred->euid, tcred->suid) ||
698 uid_eq(cred->euid, tcred->uid) ||
699 uid_eq(cred->uid, tcred->suid) ||
700 uid_eq(cred->uid, tcred->uid))
701 return 1;
702
703 if (ns_capable(tcred->user_ns, CAP_KILL))
704 return 1;
705
706 return 0;
707}
708
709/*
710 * Bad permissions for sending the signal
711 * - the caller must hold the RCU read lock
712 */
713static int check_kill_permission(int sig, struct siginfo *info,
714 struct task_struct *t)
715{
716 struct pid *sid;
717 int error;
718
719 if (!valid_signal(sig))
720 return -EINVAL;
721
722 if (!si_fromuser(info))
723 return 0;
724
725 error = audit_signal_info(sig, t); /* Let audit system see the signal */
726 if (error)
727 return error;
728
729 if (!same_thread_group(current, t) &&
730 !kill_ok_by_cred(t)) {
731 switch (sig) {
732 case SIGCONT:
733 sid = task_session(t);
734 /*
735 * We don't return the error if sid == NULL. The
736 * task was unhashed, the caller must notice this.
737 */
738 if (!sid || sid == task_session(current))
739 break;
740 default:
741 return -EPERM;
742 }
743 }
744
745 return security_task_kill(t, info, sig, 0);
746}
747
748/**
749 * ptrace_trap_notify - schedule trap to notify ptracer
750 * @t: tracee wanting to notify tracer
751 *
752 * This function schedules sticky ptrace trap which is cleared on the next
753 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
754 * ptracer.
755 *
756 * If @t is running, STOP trap will be taken. If trapped for STOP and
757 * ptracer is listening for events, tracee is woken up so that it can
758 * re-trap for the new event. If trapped otherwise, STOP trap will be
759 * eventually taken without returning to userland after the existing traps
760 * are finished by PTRACE_CONT.
761 *
762 * CONTEXT:
763 * Must be called with @task->sighand->siglock held.
764 */
765static void ptrace_trap_notify(struct task_struct *t)
766{
767 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
768 assert_spin_locked(&t->sighand->siglock);
769
770 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
771 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
772}
773
774/*
775 * Handle magic process-wide effects of stop/continue signals. Unlike
776 * the signal actions, these happen immediately at signal-generation
777 * time regardless of blocking, ignoring, or handling. This does the
778 * actual continuing for SIGCONT, but not the actual stopping for stop
779 * signals. The process stop is done as a signal action for SIG_DFL.
780 *
781 * Returns true if the signal should be actually delivered, otherwise
782 * it should be dropped.
783 */
784static bool prepare_signal(int sig, struct task_struct *p, bool force)
785{
786 struct signal_struct *signal = p->signal;
787 struct task_struct *t;
788 sigset_t flush;
789
790 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
791 if (!(signal->flags & SIGNAL_GROUP_EXIT))
792 return sig == SIGKILL;
793 /*
794 * The process is in the middle of dying, nothing to do.
795 */
796 } else if (sig_kernel_stop(sig)) {
797 /*
798 * This is a stop signal. Remove SIGCONT from all queues.
799 */
800 siginitset(&flush, sigmask(SIGCONT));
801 flush_sigqueue_mask(&flush, &signal->shared_pending);
802 for_each_thread(p, t)
803 flush_sigqueue_mask(&flush, &t->pending);
804 } else if (sig == SIGCONT) {
805 unsigned int why;
806 /*
807 * Remove all stop signals from all queues, wake all threads.
808 */
809 siginitset(&flush, SIG_KERNEL_STOP_MASK);
810 flush_sigqueue_mask(&flush, &signal->shared_pending);
811 for_each_thread(p, t) {
812 flush_sigqueue_mask(&flush, &t->pending);
813 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
814 if (likely(!(t->ptrace & PT_SEIZED)))
815 wake_up_state(t, __TASK_STOPPED);
816 else
817 ptrace_trap_notify(t);
818 }
819
820 /*
821 * Notify the parent with CLD_CONTINUED if we were stopped.
822 *
823 * If we were in the middle of a group stop, we pretend it
824 * was already finished, and then continued. Since SIGCHLD
825 * doesn't queue we report only CLD_STOPPED, as if the next
826 * CLD_CONTINUED was dropped.
827 */
828 why = 0;
829 if (signal->flags & SIGNAL_STOP_STOPPED)
830 why |= SIGNAL_CLD_CONTINUED;
831 else if (signal->group_stop_count)
832 why |= SIGNAL_CLD_STOPPED;
833
834 if (why) {
835 /*
836 * The first thread which returns from do_signal_stop()
837 * will take ->siglock, notice SIGNAL_CLD_MASK, and
838 * notify its parent. See get_signal_to_deliver().
839 */
840 signal->flags = why | SIGNAL_STOP_CONTINUED;
841 signal->group_stop_count = 0;
842 signal->group_exit_code = 0;
843 }
844 }
845
846 return !sig_ignored(p, sig, force);
847}
848
849/*
850 * Test if P wants to take SIG. After we've checked all threads with this,
851 * it's equivalent to finding no threads not blocking SIG. Any threads not
852 * blocking SIG were ruled out because they are not running and already
853 * have pending signals. Such threads will dequeue from the shared queue
854 * as soon as they're available, so putting the signal on the shared queue
855 * will be equivalent to sending it to one such thread.
856 */
857static inline int wants_signal(int sig, struct task_struct *p)
858{
859 if (sigismember(&p->blocked, sig))
860 return 0;
861 if (p->flags & PF_EXITING)
862 return 0;
863 if (sig == SIGKILL)
864 return 1;
865 if (task_is_stopped_or_traced(p))
866 return 0;
867 return task_curr(p) || !signal_pending(p);
868}
869
870static void complete_signal(int sig, struct task_struct *p, int group)
871{
872 struct signal_struct *signal = p->signal;
873 struct task_struct *t;
874
875 /*
876 * Now find a thread we can wake up to take the signal off the queue.
877 *
878 * If the main thread wants the signal, it gets first crack.
879 * Probably the least surprising to the average bear.
880 */
881 if (wants_signal(sig, p))
882 t = p;
883 else if (!group || thread_group_empty(p))
884 /*
885 * There is just one thread and it does not need to be woken.
886 * It will dequeue unblocked signals before it runs again.
887 */
888 return;
889 else {
890 /*
891 * Otherwise try to find a suitable thread.
892 */
893 t = signal->curr_target;
894 while (!wants_signal(sig, t)) {
895 t = next_thread(t);
896 if (t == signal->curr_target)
897 /*
898 * No thread needs to be woken.
899 * Any eligible threads will see
900 * the signal in the queue soon.
901 */
902 return;
903 }
904 signal->curr_target = t;
905 }
906
907 /*
908 * Found a killable thread. If the signal will be fatal,
909 * then start taking the whole group down immediately.
910 */
911 if (sig_fatal(p, sig) &&
912 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
913 !sigismember(&t->real_blocked, sig) &&
914 (sig == SIGKILL || !t->ptrace)) {
915 /*
916 * This signal will be fatal to the whole group.
917 */
918 if (!sig_kernel_coredump(sig)) {
919 /*
920 * Start a group exit and wake everybody up.
921 * This way we don't have other threads
922 * running and doing things after a slower
923 * thread has the fatal signal pending.
924 */
925 signal->flags = SIGNAL_GROUP_EXIT;
926 signal->group_exit_code = sig;
927 signal->group_stop_count = 0;
928 t = p;
929 do {
930 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
931 sigaddset(&t->pending.signal, SIGKILL);
932 signal_wake_up(t, 1);
933 } while_each_thread(p, t);
934 return;
935 }
936 }
937
938 /*
939 * The signal is already in the shared-pending queue.
940 * Tell the chosen thread to wake up and dequeue it.
941 */
942 signal_wake_up(t, sig == SIGKILL);
943 return;
944}
945
946static inline int legacy_queue(struct sigpending *signals, int sig)
947{
948 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
949}
950
951#ifdef CONFIG_USER_NS
952static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
953{
954 if (current_user_ns() == task_cred_xxx(t, user_ns))
955 return;
956
957 if (SI_FROMKERNEL(info))
958 return;
959
960 rcu_read_lock();
961 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
962 make_kuid(current_user_ns(), info->si_uid));
963 rcu_read_unlock();
964}
965#else
966static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
967{
968 return;
969}
970#endif
971
972static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
973 int group, int from_ancestor_ns)
974{
975 struct sigpending *pending;
976 struct sigqueue *q;
977 int override_rlimit;
978 int ret = 0, result;
979
980 assert_spin_locked(&t->sighand->siglock);
981
982 result = TRACE_SIGNAL_IGNORED;
983 if (!prepare_signal(sig, t,
984 from_ancestor_ns || (info == SEND_SIG_FORCED)))
985 goto ret;
986
987 pending = group ? &t->signal->shared_pending : &t->pending;
988 /*
989 * Short-circuit ignored signals and support queuing
990 * exactly one non-rt signal, so that we can get more
991 * detailed information about the cause of the signal.
992 */
993 result = TRACE_SIGNAL_ALREADY_PENDING;
994 if (legacy_queue(pending, sig))
995 goto ret;
996
997 result = TRACE_SIGNAL_DELIVERED;
998 /*
999 * fast-pathed signals for kernel-internal things like SIGSTOP
1000 * or SIGKILL.
1001 */
1002 if (info == SEND_SIG_FORCED)
1003 goto out_set;
1004
1005 /*
1006 * Real-time signals must be queued if sent by sigqueue, or
1007 * some other real-time mechanism. It is implementation
1008 * defined whether kill() does so. We attempt to do so, on
1009 * the principle of least surprise, but since kill is not
1010 * allowed to fail with EAGAIN when low on memory we just
1011 * make sure at least one signal gets delivered and don't
1012 * pass on the info struct.
1013 */
1014 if (sig < SIGRTMIN)
1015 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1016 else
1017 override_rlimit = 0;
1018
1019 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1020 override_rlimit);
1021 if (q) {
1022 list_add_tail(&q->list, &pending->list);
1023 switch ((unsigned long) info) {
1024 case (unsigned long) SEND_SIG_NOINFO:
1025 q->info.si_signo = sig;
1026 q->info.si_errno = 0;
1027 q->info.si_code = SI_USER;
1028 q->info.si_pid = task_tgid_nr_ns(current,
1029 task_active_pid_ns(t));
1030 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1031 break;
1032 case (unsigned long) SEND_SIG_PRIV:
1033 q->info.si_signo = sig;
1034 q->info.si_errno = 0;
1035 q->info.si_code = SI_KERNEL;
1036 q->info.si_pid = 0;
1037 q->info.si_uid = 0;
1038 break;
1039 default:
1040 copy_siginfo(&q->info, info);
1041 if (from_ancestor_ns)
1042 q->info.si_pid = 0;
1043 break;
1044 }
1045
1046 userns_fixup_signal_uid(&q->info, t);
1047
1048 } else if (!is_si_special(info)) {
1049 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1050 /*
1051 * Queue overflow, abort. We may abort if the
1052 * signal was rt and sent by user using something
1053 * other than kill().
1054 */
1055 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1056 ret = -EAGAIN;
1057 goto ret;
1058 } else {
1059 /*
1060 * This is a silent loss of information. We still
1061 * send the signal, but the *info bits are lost.
1062 */
1063 result = TRACE_SIGNAL_LOSE_INFO;
1064 }
1065 }
1066
1067out_set:
1068 signalfd_notify(t, sig);
1069 sigaddset(&pending->signal, sig);
1070 complete_signal(sig, t, group);
1071ret:
1072 trace_signal_generate(sig, info, t, group, result);
1073 return ret;
1074}
1075
1076static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1077 int group)
1078{
1079 int from_ancestor_ns = 0;
1080
1081#ifdef CONFIG_PID_NS
1082 from_ancestor_ns = si_fromuser(info) &&
1083 !task_pid_nr_ns(current, task_active_pid_ns(t));
1084#endif
1085
1086 return __send_signal(sig, info, t, group, from_ancestor_ns);
1087}
1088
1089static void print_fatal_signal(int signr)
1090{
1091 struct pt_regs *regs = signal_pt_regs();
1092 printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1093
1094#if defined(__i386__) && !defined(__arch_um__)
1095 printk(KERN_INFO "code at %08lx: ", regs->ip);
1096 {
1097 int i;
1098 for (i = 0; i < 16; i++) {
1099 unsigned char insn;
1100
1101 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1102 break;
1103 printk(KERN_CONT "%02x ", insn);
1104 }
1105 }
1106 printk(KERN_CONT "\n");
1107#endif
1108 preempt_disable();
1109 show_regs(regs);
1110 preempt_enable();
1111}
1112
1113static int __init setup_print_fatal_signals(char *str)
1114{
1115 get_option (&str, &print_fatal_signals);
1116
1117 return 1;
1118}
1119
1120__setup("print-fatal-signals=", setup_print_fatal_signals);
1121
1122int
1123__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1124{
1125 return send_signal(sig, info, p, 1);
1126}
1127
1128static int
1129specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1130{
1131 return send_signal(sig, info, t, 0);
1132}
1133
1134int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1135 bool group)
1136{
1137 unsigned long flags;
1138 int ret = -ESRCH;
1139
1140 if (lock_task_sighand(p, &flags)) {
1141 ret = send_signal(sig, info, p, group);
1142 unlock_task_sighand(p, &flags);
1143 }
1144
1145 return ret;
1146}
1147
1148/*
1149 * Force a signal that the process can't ignore: if necessary
1150 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1151 *
1152 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1153 * since we do not want to have a signal handler that was blocked
1154 * be invoked when user space had explicitly blocked it.
1155 *
1156 * We don't want to have recursive SIGSEGV's etc, for example,
1157 * that is why we also clear SIGNAL_UNKILLABLE.
1158 */
1159int
1160force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1161{
1162 unsigned long int flags;
1163 int ret, blocked, ignored;
1164 struct k_sigaction *action;
1165
1166 spin_lock_irqsave(&t->sighand->siglock, flags);
1167 action = &t->sighand->action[sig-1];
1168 ignored = action->sa.sa_handler == SIG_IGN;
1169 blocked = sigismember(&t->blocked, sig);
1170 if (blocked || ignored) {
1171 action->sa.sa_handler = SIG_DFL;
1172 if (blocked) {
1173 sigdelset(&t->blocked, sig);
1174 recalc_sigpending_and_wake(t);
1175 }
1176 }
1177 if (action->sa.sa_handler == SIG_DFL)
1178 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1179 ret = specific_send_sig_info(sig, info, t);
1180 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1181
1182 return ret;
1183}
1184
1185/*
1186 * Nuke all other threads in the group.
1187 */
1188int zap_other_threads(struct task_struct *p)
1189{
1190 struct task_struct *t = p;
1191 int count = 0;
1192
1193 p->signal->group_stop_count = 0;
1194
1195 while_each_thread(p, t) {
1196 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1197 count++;
1198
1199 /* Don't bother with already dead threads */
1200 if (t->exit_state)
1201 continue;
1202 sigaddset(&t->pending.signal, SIGKILL);
1203 signal_wake_up(t, 1);
1204 }
1205
1206 return count;
1207}
1208
1209struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1210 unsigned long *flags)
1211{
1212 struct sighand_struct *sighand;
1213
1214 for (;;) {
1215 /*
1216 * Disable interrupts early to avoid deadlocks.
1217 * See rcu_read_unlock() comment header for details.
1218 */
1219 local_irq_save(*flags);
1220 rcu_read_lock();
1221 sighand = rcu_dereference(tsk->sighand);
1222 if (unlikely(sighand == NULL)) {
1223 rcu_read_unlock();
1224 local_irq_restore(*flags);
1225 break;
1226 }
1227 /*
1228 * This sighand can be already freed and even reused, but
1229 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1230 * initializes ->siglock: this slab can't go away, it has
1231 * the same object type, ->siglock can't be reinitialized.
1232 *
1233 * We need to ensure that tsk->sighand is still the same
1234 * after we take the lock, we can race with de_thread() or
1235 * __exit_signal(). In the latter case the next iteration
1236 * must see ->sighand == NULL.
1237 */
1238 spin_lock(&sighand->siglock);
1239 if (likely(sighand == tsk->sighand)) {
1240 rcu_read_unlock();
1241 break;
1242 }
1243 spin_unlock(&sighand->siglock);
1244 rcu_read_unlock();
1245 local_irq_restore(*flags);
1246 }
1247
1248 return sighand;
1249}
1250
1251/*
1252 * send signal info to all the members of a group
1253 */
1254int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1255{
1256 int ret;
1257
1258 rcu_read_lock();
1259 ret = check_kill_permission(sig, info, p);
1260 rcu_read_unlock();
1261
1262 if (!ret && sig)
1263 ret = do_send_sig_info(sig, info, p, true);
1264
1265 return ret;
1266}
1267
1268/*
1269 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1270 * control characters do (^C, ^Z etc)
1271 * - the caller must hold at least a readlock on tasklist_lock
1272 */
1273int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1274{
1275 struct task_struct *p = NULL;
1276 int retval, success;
1277
1278 success = 0;
1279 retval = -ESRCH;
1280 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1281 int err = group_send_sig_info(sig, info, p);
1282 success |= !err;
1283 retval = err;
1284 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1285 return success ? 0 : retval;
1286}
1287
1288int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1289{
1290 int error = -ESRCH;
1291 struct task_struct *p;
1292
1293 for (;;) {
1294 rcu_read_lock();
1295 p = pid_task(pid, PIDTYPE_PID);
1296 if (p)
1297 error = group_send_sig_info(sig, info, p);
1298 rcu_read_unlock();
1299 if (likely(!p || error != -ESRCH))
1300 return error;
1301
1302 /*
1303 * The task was unhashed in between, try again. If it
1304 * is dead, pid_task() will return NULL, if we race with
1305 * de_thread() it will find the new leader.
1306 */
1307 }
1308}
1309
1310int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1311{
1312 int error;
1313 rcu_read_lock();
1314 error = kill_pid_info(sig, info, find_vpid(pid));
1315 rcu_read_unlock();
1316 return error;
1317}
1318
1319static int kill_as_cred_perm(const struct cred *cred,
1320 struct task_struct *target)
1321{
1322 const struct cred *pcred = __task_cred(target);
1323 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1324 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1325 return 0;
1326 return 1;
1327}
1328
1329/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1330int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1331 const struct cred *cred, u32 secid)
1332{
1333 int ret = -EINVAL;
1334 struct task_struct *p;
1335 unsigned long flags;
1336
1337 if (!valid_signal(sig))
1338 return ret;
1339
1340 rcu_read_lock();
1341 p = pid_task(pid, PIDTYPE_PID);
1342 if (!p) {
1343 ret = -ESRCH;
1344 goto out_unlock;
1345 }
1346 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1347 ret = -EPERM;
1348 goto out_unlock;
1349 }
1350 ret = security_task_kill(p, info, sig, secid);
1351 if (ret)
1352 goto out_unlock;
1353
1354 if (sig) {
1355 if (lock_task_sighand(p, &flags)) {
1356 ret = __send_signal(sig, info, p, 1, 0);
1357 unlock_task_sighand(p, &flags);
1358 } else
1359 ret = -ESRCH;
1360 }
1361out_unlock:
1362 rcu_read_unlock();
1363 return ret;
1364}
1365EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1366
1367/*
1368 * kill_something_info() interprets pid in interesting ways just like kill(2).
1369 *
1370 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1371 * is probably wrong. Should make it like BSD or SYSV.
1372 */
1373
1374static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1375{
1376 int ret;
1377
1378 if (pid > 0) {
1379 rcu_read_lock();
1380 ret = kill_pid_info(sig, info, find_vpid(pid));
1381 rcu_read_unlock();
1382 return ret;
1383 }
1384
1385 read_lock(&tasklist_lock);
1386 if (pid != -1) {
1387 ret = __kill_pgrp_info(sig, info,
1388 pid ? find_vpid(-pid) : task_pgrp(current));
1389 } else {
1390 int retval = 0, count = 0;
1391 struct task_struct * p;
1392
1393 for_each_process(p) {
1394 if (task_pid_vnr(p) > 1 &&
1395 !same_thread_group(p, current)) {
1396 int err = group_send_sig_info(sig, info, p);
1397 ++count;
1398 if (err != -EPERM)
1399 retval = err;
1400 }
1401 }
1402 ret = count ? retval : -ESRCH;
1403 }
1404 read_unlock(&tasklist_lock);
1405
1406 return ret;
1407}
1408
1409/*
1410 * These are for backward compatibility with the rest of the kernel source.
1411 */
1412
1413int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1414{
1415 /*
1416 * Make sure legacy kernel users don't send in bad values
1417 * (normal paths check this in check_kill_permission).
1418 */
1419 if (!valid_signal(sig))
1420 return -EINVAL;
1421
1422 return do_send_sig_info(sig, info, p, false);
1423}
1424
1425#define __si_special(priv) \
1426 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1427
1428int
1429send_sig(int sig, struct task_struct *p, int priv)
1430{
1431 return send_sig_info(sig, __si_special(priv), p);
1432}
1433
1434void
1435force_sig(int sig, struct task_struct *p)
1436{
1437 force_sig_info(sig, SEND_SIG_PRIV, p);
1438}
1439
1440/*
1441 * When things go south during signal handling, we
1442 * will force a SIGSEGV. And if the signal that caused
1443 * the problem was already a SIGSEGV, we'll want to
1444 * make sure we don't even try to deliver the signal..
1445 */
1446int
1447force_sigsegv(int sig, struct task_struct *p)
1448{
1449 if (sig == SIGSEGV) {
1450 unsigned long flags;
1451 spin_lock_irqsave(&p->sighand->siglock, flags);
1452 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1453 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1454 }
1455 force_sig(SIGSEGV, p);
1456 return 0;
1457}
1458
1459int kill_pgrp(struct pid *pid, int sig, int priv)
1460{
1461 int ret;
1462
1463 read_lock(&tasklist_lock);
1464 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1465 read_unlock(&tasklist_lock);
1466
1467 return ret;
1468}
1469EXPORT_SYMBOL(kill_pgrp);
1470
1471int kill_pid(struct pid *pid, int sig, int priv)
1472{
1473 return kill_pid_info(sig, __si_special(priv), pid);
1474}
1475EXPORT_SYMBOL(kill_pid);
1476
1477/*
1478 * These functions support sending signals using preallocated sigqueue
1479 * structures. This is needed "because realtime applications cannot
1480 * afford to lose notifications of asynchronous events, like timer
1481 * expirations or I/O completions". In the case of POSIX Timers
1482 * we allocate the sigqueue structure from the timer_create. If this
1483 * allocation fails we are able to report the failure to the application
1484 * with an EAGAIN error.
1485 */
1486struct sigqueue *sigqueue_alloc(void)
1487{
1488 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1489
1490 if (q)
1491 q->flags |= SIGQUEUE_PREALLOC;
1492
1493 return q;
1494}
1495
1496void sigqueue_free(struct sigqueue *q)
1497{
1498 unsigned long flags;
1499 spinlock_t *lock = ¤t->sighand->siglock;
1500
1501 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1502 /*
1503 * We must hold ->siglock while testing q->list
1504 * to serialize with collect_signal() or with
1505 * __exit_signal()->flush_sigqueue().
1506 */
1507 spin_lock_irqsave(lock, flags);
1508 q->flags &= ~SIGQUEUE_PREALLOC;
1509 /*
1510 * If it is queued it will be freed when dequeued,
1511 * like the "regular" sigqueue.
1512 */
1513 if (!list_empty(&q->list))
1514 q = NULL;
1515 spin_unlock_irqrestore(lock, flags);
1516
1517 if (q)
1518 __sigqueue_free(q);
1519}
1520
1521int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1522{
1523 int sig = q->info.si_signo;
1524 struct sigpending *pending;
1525 unsigned long flags;
1526 int ret, result;
1527
1528 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1529
1530 ret = -1;
1531 if (!likely(lock_task_sighand(t, &flags)))
1532 goto ret;
1533
1534 ret = 1; /* the signal is ignored */
1535 result = TRACE_SIGNAL_IGNORED;
1536 if (!prepare_signal(sig, t, false))
1537 goto out;
1538
1539 ret = 0;
1540 if (unlikely(!list_empty(&q->list))) {
1541 /*
1542 * If an SI_TIMER entry is already queue just increment
1543 * the overrun count.
1544 */
1545 BUG_ON(q->info.si_code != SI_TIMER);
1546 q->info.si_overrun++;
1547 result = TRACE_SIGNAL_ALREADY_PENDING;
1548 goto out;
1549 }
1550 q->info.si_overrun = 0;
1551
1552 signalfd_notify(t, sig);
1553 pending = group ? &t->signal->shared_pending : &t->pending;
1554 list_add_tail(&q->list, &pending->list);
1555 sigaddset(&pending->signal, sig);
1556 complete_signal(sig, t, group);
1557 result = TRACE_SIGNAL_DELIVERED;
1558out:
1559 trace_signal_generate(sig, &q->info, t, group, result);
1560 unlock_task_sighand(t, &flags);
1561ret:
1562 return ret;
1563}
1564
1565/*
1566 * Let a parent know about the death of a child.
1567 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1568 *
1569 * Returns true if our parent ignored us and so we've switched to
1570 * self-reaping.
1571 */
1572bool do_notify_parent(struct task_struct *tsk, int sig)
1573{
1574 struct siginfo info;
1575 unsigned long flags;
1576 struct sighand_struct *psig;
1577 bool autoreap = false;
1578 cputime_t utime, stime;
1579
1580 BUG_ON(sig == -1);
1581
1582 /* do_notify_parent_cldstop should have been called instead. */
1583 BUG_ON(task_is_stopped_or_traced(tsk));
1584
1585 BUG_ON(!tsk->ptrace &&
1586 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1587
1588 if (sig != SIGCHLD) {
1589 /*
1590 * This is only possible if parent == real_parent.
1591 * Check if it has changed security domain.
1592 */
1593 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1594 sig = SIGCHLD;
1595 }
1596
1597 info.si_signo = sig;
1598 info.si_errno = 0;
1599 /*
1600 * We are under tasklist_lock here so our parent is tied to
1601 * us and cannot change.
1602 *
1603 * task_active_pid_ns will always return the same pid namespace
1604 * until a task passes through release_task.
1605 *
1606 * write_lock() currently calls preempt_disable() which is the
1607 * same as rcu_read_lock(), but according to Oleg, this is not
1608 * correct to rely on this
1609 */
1610 rcu_read_lock();
1611 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1612 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1613 task_uid(tsk));
1614 rcu_read_unlock();
1615
1616 task_cputime(tsk, &utime, &stime);
1617 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1618 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1619
1620 info.si_status = tsk->exit_code & 0x7f;
1621 if (tsk->exit_code & 0x80)
1622 info.si_code = CLD_DUMPED;
1623 else if (tsk->exit_code & 0x7f)
1624 info.si_code = CLD_KILLED;
1625 else {
1626 info.si_code = CLD_EXITED;
1627 info.si_status = tsk->exit_code >> 8;
1628 }
1629
1630 psig = tsk->parent->sighand;
1631 spin_lock_irqsave(&psig->siglock, flags);
1632 if (!tsk->ptrace && sig == SIGCHLD &&
1633 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1634 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1635 /*
1636 * We are exiting and our parent doesn't care. POSIX.1
1637 * defines special semantics for setting SIGCHLD to SIG_IGN
1638 * or setting the SA_NOCLDWAIT flag: we should be reaped
1639 * automatically and not left for our parent's wait4 call.
1640 * Rather than having the parent do it as a magic kind of
1641 * signal handler, we just set this to tell do_exit that we
1642 * can be cleaned up without becoming a zombie. Note that
1643 * we still call __wake_up_parent in this case, because a
1644 * blocked sys_wait4 might now return -ECHILD.
1645 *
1646 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1647 * is implementation-defined: we do (if you don't want
1648 * it, just use SIG_IGN instead).
1649 */
1650 autoreap = true;
1651 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1652 sig = 0;
1653 }
1654 if (valid_signal(sig) && sig)
1655 __group_send_sig_info(sig, &info, tsk->parent);
1656 __wake_up_parent(tsk, tsk->parent);
1657 spin_unlock_irqrestore(&psig->siglock, flags);
1658
1659 return autoreap;
1660}
1661
1662/**
1663 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1664 * @tsk: task reporting the state change
1665 * @for_ptracer: the notification is for ptracer
1666 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1667 *
1668 * Notify @tsk's parent that the stopped/continued state has changed. If
1669 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1670 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1671 *
1672 * CONTEXT:
1673 * Must be called with tasklist_lock at least read locked.
1674 */
1675static void do_notify_parent_cldstop(struct task_struct *tsk,
1676 bool for_ptracer, int why)
1677{
1678 struct siginfo info;
1679 unsigned long flags;
1680 struct task_struct *parent;
1681 struct sighand_struct *sighand;
1682 cputime_t utime, stime;
1683
1684 if (for_ptracer) {
1685 parent = tsk->parent;
1686 } else {
1687 tsk = tsk->group_leader;
1688 parent = tsk->real_parent;
1689 }
1690
1691 info.si_signo = SIGCHLD;
1692 info.si_errno = 0;
1693 /*
1694 * see comment in do_notify_parent() about the following 4 lines
1695 */
1696 rcu_read_lock();
1697 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1698 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1699 rcu_read_unlock();
1700
1701 task_cputime(tsk, &utime, &stime);
1702 info.si_utime = cputime_to_clock_t(utime);
1703 info.si_stime = cputime_to_clock_t(stime);
1704
1705 info.si_code = why;
1706 switch (why) {
1707 case CLD_CONTINUED:
1708 info.si_status = SIGCONT;
1709 break;
1710 case CLD_STOPPED:
1711 info.si_status = tsk->signal->group_exit_code & 0x7f;
1712 break;
1713 case CLD_TRAPPED:
1714 info.si_status = tsk->exit_code & 0x7f;
1715 break;
1716 default:
1717 BUG();
1718 }
1719
1720 sighand = parent->sighand;
1721 spin_lock_irqsave(&sighand->siglock, flags);
1722 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1723 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1724 __group_send_sig_info(SIGCHLD, &info, parent);
1725 /*
1726 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1727 */
1728 __wake_up_parent(tsk, parent);
1729 spin_unlock_irqrestore(&sighand->siglock, flags);
1730}
1731
1732static inline int may_ptrace_stop(void)
1733{
1734 if (!likely(current->ptrace))
1735 return 0;
1736 /*
1737 * Are we in the middle of do_coredump?
1738 * If so and our tracer is also part of the coredump stopping
1739 * is a deadlock situation, and pointless because our tracer
1740 * is dead so don't allow us to stop.
1741 * If SIGKILL was already sent before the caller unlocked
1742 * ->siglock we must see ->core_state != NULL. Otherwise it
1743 * is safe to enter schedule().
1744 *
1745 * This is almost outdated, a task with the pending SIGKILL can't
1746 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1747 * after SIGKILL was already dequeued.
1748 */
1749 if (unlikely(current->mm->core_state) &&
1750 unlikely(current->mm == current->parent->mm))
1751 return 0;
1752
1753 return 1;
1754}
1755
1756/*
1757 * Return non-zero if there is a SIGKILL that should be waking us up.
1758 * Called with the siglock held.
1759 */
1760static int sigkill_pending(struct task_struct *tsk)
1761{
1762 return sigismember(&tsk->pending.signal, SIGKILL) ||
1763 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1764}
1765
1766/*
1767 * This must be called with current->sighand->siglock held.
1768 *
1769 * This should be the path for all ptrace stops.
1770 * We always set current->last_siginfo while stopped here.
1771 * That makes it a way to test a stopped process for
1772 * being ptrace-stopped vs being job-control-stopped.
1773 *
1774 * If we actually decide not to stop at all because the tracer
1775 * is gone, we keep current->exit_code unless clear_code.
1776 */
1777static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1778 __releases(¤t->sighand->siglock)
1779 __acquires(¤t->sighand->siglock)
1780{
1781 bool gstop_done = false;
1782
1783 if (arch_ptrace_stop_needed(exit_code, info)) {
1784 /*
1785 * The arch code has something special to do before a
1786 * ptrace stop. This is allowed to block, e.g. for faults
1787 * on user stack pages. We can't keep the siglock while
1788 * calling arch_ptrace_stop, so we must release it now.
1789 * To preserve proper semantics, we must do this before
1790 * any signal bookkeeping like checking group_stop_count.
1791 * Meanwhile, a SIGKILL could come in before we retake the
1792 * siglock. That must prevent us from sleeping in TASK_TRACED.
1793 * So after regaining the lock, we must check for SIGKILL.
1794 */
1795 spin_unlock_irq(¤t->sighand->siglock);
1796 arch_ptrace_stop(exit_code, info);
1797 spin_lock_irq(¤t->sighand->siglock);
1798 if (sigkill_pending(current))
1799 return;
1800 }
1801
1802 /*
1803 * We're committing to trapping. TRACED should be visible before
1804 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1805 * Also, transition to TRACED and updates to ->jobctl should be
1806 * atomic with respect to siglock and should be done after the arch
1807 * hook as siglock is released and regrabbed across it.
1808 */
1809 set_current_state(TASK_TRACED);
1810
1811 current->last_siginfo = info;
1812 current->exit_code = exit_code;
1813
1814 /*
1815 * If @why is CLD_STOPPED, we're trapping to participate in a group
1816 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1817 * across siglock relocks since INTERRUPT was scheduled, PENDING
1818 * could be clear now. We act as if SIGCONT is received after
1819 * TASK_TRACED is entered - ignore it.
1820 */
1821 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1822 gstop_done = task_participate_group_stop(current);
1823
1824 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1825 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1826 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1827 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1828
1829 /* entering a trap, clear TRAPPING */
1830 task_clear_jobctl_trapping(current);
1831
1832 spin_unlock_irq(¤t->sighand->siglock);
1833 read_lock(&tasklist_lock);
1834 if (may_ptrace_stop()) {
1835 /*
1836 * Notify parents of the stop.
1837 *
1838 * While ptraced, there are two parents - the ptracer and
1839 * the real_parent of the group_leader. The ptracer should
1840 * know about every stop while the real parent is only
1841 * interested in the completion of group stop. The states
1842 * for the two don't interact with each other. Notify
1843 * separately unless they're gonna be duplicates.
1844 */
1845 do_notify_parent_cldstop(current, true, why);
1846 if (gstop_done && ptrace_reparented(current))
1847 do_notify_parent_cldstop(current, false, why);
1848
1849 /*
1850 * Don't want to allow preemption here, because
1851 * sys_ptrace() needs this task to be inactive.
1852 *
1853 * XXX: implement read_unlock_no_resched().
1854 */
1855 preempt_disable();
1856 read_unlock(&tasklist_lock);
1857 preempt_enable_no_resched();
1858 freezable_schedule();
1859 } else {
1860 /*
1861 * By the time we got the lock, our tracer went away.
1862 * Don't drop the lock yet, another tracer may come.
1863 *
1864 * If @gstop_done, the ptracer went away between group stop
1865 * completion and here. During detach, it would have set
1866 * JOBCTL_STOP_PENDING on us and we'll re-enter
1867 * TASK_STOPPED in do_signal_stop() on return, so notifying
1868 * the real parent of the group stop completion is enough.
1869 */
1870 if (gstop_done)
1871 do_notify_parent_cldstop(current, false, why);
1872
1873 /* tasklist protects us from ptrace_freeze_traced() */
1874 __set_current_state(TASK_RUNNING);
1875 if (clear_code)
1876 current->exit_code = 0;
1877 read_unlock(&tasklist_lock);
1878 }
1879
1880 /*
1881 * We are back. Now reacquire the siglock before touching
1882 * last_siginfo, so that we are sure to have synchronized with
1883 * any signal-sending on another CPU that wants to examine it.
1884 */
1885 spin_lock_irq(¤t->sighand->siglock);
1886 current->last_siginfo = NULL;
1887
1888 /* LISTENING can be set only during STOP traps, clear it */
1889 current->jobctl &= ~JOBCTL_LISTENING;
1890
1891 /*
1892 * Queued signals ignored us while we were stopped for tracing.
1893 * So check for any that we should take before resuming user mode.
1894 * This sets TIF_SIGPENDING, but never clears it.
1895 */
1896 recalc_sigpending_tsk(current);
1897}
1898
1899static void ptrace_do_notify(int signr, int exit_code, int why)
1900{
1901 siginfo_t info;
1902
1903 memset(&info, 0, sizeof info);
1904 info.si_signo = signr;
1905 info.si_code = exit_code;
1906 info.si_pid = task_pid_vnr(current);
1907 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1908
1909 /* Let the debugger run. */
1910 ptrace_stop(exit_code, why, 1, &info);
1911}
1912
1913void ptrace_notify(int exit_code)
1914{
1915 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1916 if (unlikely(current->task_works))
1917 task_work_run();
1918
1919 spin_lock_irq(¤t->sighand->siglock);
1920 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1921 spin_unlock_irq(¤t->sighand->siglock);
1922}
1923
1924/**
1925 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1926 * @signr: signr causing group stop if initiating
1927 *
1928 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1929 * and participate in it. If already set, participate in the existing
1930 * group stop. If participated in a group stop (and thus slept), %true is
1931 * returned with siglock released.
1932 *
1933 * If ptraced, this function doesn't handle stop itself. Instead,
1934 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1935 * untouched. The caller must ensure that INTERRUPT trap handling takes
1936 * places afterwards.
1937 *
1938 * CONTEXT:
1939 * Must be called with @current->sighand->siglock held, which is released
1940 * on %true return.
1941 *
1942 * RETURNS:
1943 * %false if group stop is already cancelled or ptrace trap is scheduled.
1944 * %true if participated in group stop.
1945 */
1946static bool do_signal_stop(int signr)
1947 __releases(¤t->sighand->siglock)
1948{
1949 struct signal_struct *sig = current->signal;
1950
1951 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1952 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1953 struct task_struct *t;
1954
1955 /* signr will be recorded in task->jobctl for retries */
1956 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1957
1958 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1959 unlikely(signal_group_exit(sig)))
1960 return false;
1961 /*
1962 * There is no group stop already in progress. We must
1963 * initiate one now.
1964 *
1965 * While ptraced, a task may be resumed while group stop is
1966 * still in effect and then receive a stop signal and
1967 * initiate another group stop. This deviates from the
1968 * usual behavior as two consecutive stop signals can't
1969 * cause two group stops when !ptraced. That is why we
1970 * also check !task_is_stopped(t) below.
1971 *
1972 * The condition can be distinguished by testing whether
1973 * SIGNAL_STOP_STOPPED is already set. Don't generate
1974 * group_exit_code in such case.
1975 *
1976 * This is not necessary for SIGNAL_STOP_CONTINUED because
1977 * an intervening stop signal is required to cause two
1978 * continued events regardless of ptrace.
1979 */
1980 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1981 sig->group_exit_code = signr;
1982
1983 sig->group_stop_count = 0;
1984
1985 if (task_set_jobctl_pending(current, signr | gstop))
1986 sig->group_stop_count++;
1987
1988 t = current;
1989 while_each_thread(current, t) {
1990 /*
1991 * Setting state to TASK_STOPPED for a group
1992 * stop is always done with the siglock held,
1993 * so this check has no races.
1994 */
1995 if (!task_is_stopped(t) &&
1996 task_set_jobctl_pending(t, signr | gstop)) {
1997 sig->group_stop_count++;
1998 if (likely(!(t->ptrace & PT_SEIZED)))
1999 signal_wake_up(t, 0);
2000 else
2001 ptrace_trap_notify(t);
2002 }
2003 }
2004 }
2005
2006 if (likely(!current->ptrace)) {
2007 int notify = 0;
2008
2009 /*
2010 * If there are no other threads in the group, or if there
2011 * is a group stop in progress and we are the last to stop,
2012 * report to the parent.
2013 */
2014 if (task_participate_group_stop(current))
2015 notify = CLD_STOPPED;
2016
2017 __set_current_state(TASK_STOPPED);
2018 spin_unlock_irq(¤t->sighand->siglock);
2019
2020 /*
2021 * Notify the parent of the group stop completion. Because
2022 * we're not holding either the siglock or tasklist_lock
2023 * here, ptracer may attach inbetween; however, this is for
2024 * group stop and should always be delivered to the real
2025 * parent of the group leader. The new ptracer will get
2026 * its notification when this task transitions into
2027 * TASK_TRACED.
2028 */
2029 if (notify) {
2030 read_lock(&tasklist_lock);
2031 do_notify_parent_cldstop(current, false, notify);
2032 read_unlock(&tasklist_lock);
2033 }
2034
2035 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2036 freezable_schedule();
2037 return true;
2038 } else {
2039 /*
2040 * While ptraced, group stop is handled by STOP trap.
2041 * Schedule it and let the caller deal with it.
2042 */
2043 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2044 return false;
2045 }
2046}
2047
2048/**
2049 * do_jobctl_trap - take care of ptrace jobctl traps
2050 *
2051 * When PT_SEIZED, it's used for both group stop and explicit
2052 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2053 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2054 * the stop signal; otherwise, %SIGTRAP.
2055 *
2056 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2057 * number as exit_code and no siginfo.
2058 *
2059 * CONTEXT:
2060 * Must be called with @current->sighand->siglock held, which may be
2061 * released and re-acquired before returning with intervening sleep.
2062 */
2063static void do_jobctl_trap(void)
2064{
2065 struct signal_struct *signal = current->signal;
2066 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2067
2068 if (current->ptrace & PT_SEIZED) {
2069 if (!signal->group_stop_count &&
2070 !(signal->flags & SIGNAL_STOP_STOPPED))
2071 signr = SIGTRAP;
2072 WARN_ON_ONCE(!signr);
2073 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2074 CLD_STOPPED);
2075 } else {
2076 WARN_ON_ONCE(!signr);
2077 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2078 current->exit_code = 0;
2079 }
2080}
2081
2082static int ptrace_signal(int signr, siginfo_t *info)
2083{
2084 ptrace_signal_deliver();
2085 /*
2086 * We do not check sig_kernel_stop(signr) but set this marker
2087 * unconditionally because we do not know whether debugger will
2088 * change signr. This flag has no meaning unless we are going
2089 * to stop after return from ptrace_stop(). In this case it will
2090 * be checked in do_signal_stop(), we should only stop if it was
2091 * not cleared by SIGCONT while we were sleeping. See also the
2092 * comment in dequeue_signal().
2093 */
2094 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2095 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2096
2097 /* We're back. Did the debugger cancel the sig? */
2098 signr = current->exit_code;
2099 if (signr == 0)
2100 return signr;
2101
2102 current->exit_code = 0;
2103
2104 /*
2105 * Update the siginfo structure if the signal has
2106 * changed. If the debugger wanted something
2107 * specific in the siginfo structure then it should
2108 * have updated *info via PTRACE_SETSIGINFO.
2109 */
2110 if (signr != info->si_signo) {
2111 info->si_signo = signr;
2112 info->si_errno = 0;
2113 info->si_code = SI_USER;
2114 rcu_read_lock();
2115 info->si_pid = task_pid_vnr(current->parent);
2116 info->si_uid = from_kuid_munged(current_user_ns(),
2117 task_uid(current->parent));
2118 rcu_read_unlock();
2119 }
2120
2121 /* If the (new) signal is now blocked, requeue it. */
2122 if (sigismember(¤t->blocked, signr)) {
2123 specific_send_sig_info(signr, info, current);
2124 signr = 0;
2125 }
2126
2127 return signr;
2128}
2129
2130int get_signal(struct ksignal *ksig)
2131{
2132 struct sighand_struct *sighand = current->sighand;
2133 struct signal_struct *signal = current->signal;
2134 int signr;
2135
2136 if (unlikely(current->task_works))
2137 task_work_run();
2138
2139 if (unlikely(uprobe_deny_signal()))
2140 return 0;
2141
2142 /*
2143 * Do this once, we can't return to user-mode if freezing() == T.
2144 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2145 * thus do not need another check after return.
2146 */
2147 try_to_freeze();
2148
2149relock:
2150 spin_lock_irq(&sighand->siglock);
2151 /*
2152 * Every stopped thread goes here after wakeup. Check to see if
2153 * we should notify the parent, prepare_signal(SIGCONT) encodes
2154 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2155 */
2156 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2157 int why;
2158
2159 if (signal->flags & SIGNAL_CLD_CONTINUED)
2160 why = CLD_CONTINUED;
2161 else
2162 why = CLD_STOPPED;
2163
2164 signal->flags &= ~SIGNAL_CLD_MASK;
2165
2166 spin_unlock_irq(&sighand->siglock);
2167
2168 /*
2169 * Notify the parent that we're continuing. This event is
2170 * always per-process and doesn't make whole lot of sense
2171 * for ptracers, who shouldn't consume the state via
2172 * wait(2) either, but, for backward compatibility, notify
2173 * the ptracer of the group leader too unless it's gonna be
2174 * a duplicate.
2175 */
2176 read_lock(&tasklist_lock);
2177 do_notify_parent_cldstop(current, false, why);
2178
2179 if (ptrace_reparented(current->group_leader))
2180 do_notify_parent_cldstop(current->group_leader,
2181 true, why);
2182 read_unlock(&tasklist_lock);
2183
2184 goto relock;
2185 }
2186
2187 for (;;) {
2188 struct k_sigaction *ka;
2189
2190 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2191 do_signal_stop(0))
2192 goto relock;
2193
2194 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2195 do_jobctl_trap();
2196 spin_unlock_irq(&sighand->siglock);
2197 goto relock;
2198 }
2199
2200 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2201
2202 if (!signr)
2203 break; /* will return 0 */
2204
2205 if (unlikely(current->ptrace) && signr != SIGKILL) {
2206 signr = ptrace_signal(signr, &ksig->info);
2207 if (!signr)
2208 continue;
2209 }
2210
2211 ka = &sighand->action[signr-1];
2212
2213 /* Trace actually delivered signals. */
2214 trace_signal_deliver(signr, &ksig->info, ka);
2215
2216 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2217 continue;
2218 if (ka->sa.sa_handler != SIG_DFL) {
2219 /* Run the handler. */
2220 ksig->ka = *ka;
2221
2222 if (ka->sa.sa_flags & SA_ONESHOT)
2223 ka->sa.sa_handler = SIG_DFL;
2224
2225 break; /* will return non-zero "signr" value */
2226 }
2227
2228 /*
2229 * Now we are doing the default action for this signal.
2230 */
2231 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2232 continue;
2233
2234 /*
2235 * Global init gets no signals it doesn't want.
2236 * Container-init gets no signals it doesn't want from same
2237 * container.
2238 *
2239 * Note that if global/container-init sees a sig_kernel_only()
2240 * signal here, the signal must have been generated internally
2241 * or must have come from an ancestor namespace. In either
2242 * case, the signal cannot be dropped.
2243 */
2244 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2245 !sig_kernel_only(signr))
2246 continue;
2247
2248 if (sig_kernel_stop(signr)) {
2249 /*
2250 * The default action is to stop all threads in
2251 * the thread group. The job control signals
2252 * do nothing in an orphaned pgrp, but SIGSTOP
2253 * always works. Note that siglock needs to be
2254 * dropped during the call to is_orphaned_pgrp()
2255 * because of lock ordering with tasklist_lock.
2256 * This allows an intervening SIGCONT to be posted.
2257 * We need to check for that and bail out if necessary.
2258 */
2259 if (signr != SIGSTOP) {
2260 spin_unlock_irq(&sighand->siglock);
2261
2262 /* signals can be posted during this window */
2263
2264 if (is_current_pgrp_orphaned())
2265 goto relock;
2266
2267 spin_lock_irq(&sighand->siglock);
2268 }
2269
2270 if (likely(do_signal_stop(ksig->info.si_signo))) {
2271 /* It released the siglock. */
2272 goto relock;
2273 }
2274
2275 /*
2276 * We didn't actually stop, due to a race
2277 * with SIGCONT or something like that.
2278 */
2279 continue;
2280 }
2281
2282 spin_unlock_irq(&sighand->siglock);
2283
2284 /*
2285 * Anything else is fatal, maybe with a core dump.
2286 */
2287 current->flags |= PF_SIGNALED;
2288
2289 if (sig_kernel_coredump(signr)) {
2290 if (print_fatal_signals)
2291 print_fatal_signal(ksig->info.si_signo);
2292 proc_coredump_connector(current);
2293 /*
2294 * If it was able to dump core, this kills all
2295 * other threads in the group and synchronizes with
2296 * their demise. If we lost the race with another
2297 * thread getting here, it set group_exit_code
2298 * first and our do_group_exit call below will use
2299 * that value and ignore the one we pass it.
2300 */
2301 do_coredump(&ksig->info);
2302 }
2303
2304 /*
2305 * Death signals, no core dump.
2306 */
2307 do_group_exit(ksig->info.si_signo);
2308 /* NOTREACHED */
2309 }
2310 spin_unlock_irq(&sighand->siglock);
2311
2312 ksig->sig = signr;
2313 return ksig->sig > 0;
2314}
2315
2316/**
2317 * signal_delivered -
2318 * @ksig: kernel signal struct
2319 * @stepping: nonzero if debugger single-step or block-step in use
2320 *
2321 * This function should be called when a signal has successfully been
2322 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2323 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2324 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2325 */
2326static void signal_delivered(struct ksignal *ksig, int stepping)
2327{
2328 sigset_t blocked;
2329
2330 /* A signal was successfully delivered, and the
2331 saved sigmask was stored on the signal frame,
2332 and will be restored by sigreturn. So we can
2333 simply clear the restore sigmask flag. */
2334 clear_restore_sigmask();
2335
2336 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2337 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2338 sigaddset(&blocked, ksig->sig);
2339 set_current_blocked(&blocked);
2340 tracehook_signal_handler(stepping);
2341}
2342
2343void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2344{
2345 if (failed)
2346 force_sigsegv(ksig->sig, current);
2347 else
2348 signal_delivered(ksig, stepping);
2349}
2350
2351/*
2352 * It could be that complete_signal() picked us to notify about the
2353 * group-wide signal. Other threads should be notified now to take
2354 * the shared signals in @which since we will not.
2355 */
2356static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2357{
2358 sigset_t retarget;
2359 struct task_struct *t;
2360
2361 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2362 if (sigisemptyset(&retarget))
2363 return;
2364
2365 t = tsk;
2366 while_each_thread(tsk, t) {
2367 if (t->flags & PF_EXITING)
2368 continue;
2369
2370 if (!has_pending_signals(&retarget, &t->blocked))
2371 continue;
2372 /* Remove the signals this thread can handle. */
2373 sigandsets(&retarget, &retarget, &t->blocked);
2374
2375 if (!signal_pending(t))
2376 signal_wake_up(t, 0);
2377
2378 if (sigisemptyset(&retarget))
2379 break;
2380 }
2381}
2382
2383void exit_signals(struct task_struct *tsk)
2384{
2385 int group_stop = 0;
2386 sigset_t unblocked;
2387
2388 /*
2389 * @tsk is about to have PF_EXITING set - lock out users which
2390 * expect stable threadgroup.
2391 */
2392 threadgroup_change_begin(tsk);
2393
2394 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2395 tsk->flags |= PF_EXITING;
2396 threadgroup_change_end(tsk);
2397 return;
2398 }
2399
2400 spin_lock_irq(&tsk->sighand->siglock);
2401 /*
2402 * From now this task is not visible for group-wide signals,
2403 * see wants_signal(), do_signal_stop().
2404 */
2405 tsk->flags |= PF_EXITING;
2406
2407 threadgroup_change_end(tsk);
2408
2409 if (!signal_pending(tsk))
2410 goto out;
2411
2412 unblocked = tsk->blocked;
2413 signotset(&unblocked);
2414 retarget_shared_pending(tsk, &unblocked);
2415
2416 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2417 task_participate_group_stop(tsk))
2418 group_stop = CLD_STOPPED;
2419out:
2420 spin_unlock_irq(&tsk->sighand->siglock);
2421
2422 /*
2423 * If group stop has completed, deliver the notification. This
2424 * should always go to the real parent of the group leader.
2425 */
2426 if (unlikely(group_stop)) {
2427 read_lock(&tasklist_lock);
2428 do_notify_parent_cldstop(tsk, false, group_stop);
2429 read_unlock(&tasklist_lock);
2430 }
2431}
2432
2433EXPORT_SYMBOL(recalc_sigpending);
2434EXPORT_SYMBOL_GPL(dequeue_signal);
2435EXPORT_SYMBOL(flush_signals);
2436EXPORT_SYMBOL(force_sig);
2437EXPORT_SYMBOL(send_sig);
2438EXPORT_SYMBOL(send_sig_info);
2439EXPORT_SYMBOL(sigprocmask);
2440
2441/*
2442 * System call entry points.
2443 */
2444
2445/**
2446 * sys_restart_syscall - restart a system call
2447 */
2448SYSCALL_DEFINE0(restart_syscall)
2449{
2450 struct restart_block *restart = ¤t->restart_block;
2451 return restart->fn(restart);
2452}
2453
2454long do_no_restart_syscall(struct restart_block *param)
2455{
2456 return -EINTR;
2457}
2458
2459static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2460{
2461 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2462 sigset_t newblocked;
2463 /* A set of now blocked but previously unblocked signals. */
2464 sigandnsets(&newblocked, newset, ¤t->blocked);
2465 retarget_shared_pending(tsk, &newblocked);
2466 }
2467 tsk->blocked = *newset;
2468 recalc_sigpending();
2469}
2470
2471/**
2472 * set_current_blocked - change current->blocked mask
2473 * @newset: new mask
2474 *
2475 * It is wrong to change ->blocked directly, this helper should be used
2476 * to ensure the process can't miss a shared signal we are going to block.
2477 */
2478void set_current_blocked(sigset_t *newset)
2479{
2480 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2481 __set_current_blocked(newset);
2482}
2483
2484void __set_current_blocked(const sigset_t *newset)
2485{
2486 struct task_struct *tsk = current;
2487
2488 spin_lock_irq(&tsk->sighand->siglock);
2489 __set_task_blocked(tsk, newset);
2490 spin_unlock_irq(&tsk->sighand->siglock);
2491}
2492
2493/*
2494 * This is also useful for kernel threads that want to temporarily
2495 * (or permanently) block certain signals.
2496 *
2497 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2498 * interface happily blocks "unblockable" signals like SIGKILL
2499 * and friends.
2500 */
2501int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2502{
2503 struct task_struct *tsk = current;
2504 sigset_t newset;
2505
2506 /* Lockless, only current can change ->blocked, never from irq */
2507 if (oldset)
2508 *oldset = tsk->blocked;
2509
2510 switch (how) {
2511 case SIG_BLOCK:
2512 sigorsets(&newset, &tsk->blocked, set);
2513 break;
2514 case SIG_UNBLOCK:
2515 sigandnsets(&newset, &tsk->blocked, set);
2516 break;
2517 case SIG_SETMASK:
2518 newset = *set;
2519 break;
2520 default:
2521 return -EINVAL;
2522 }
2523
2524 __set_current_blocked(&newset);
2525 return 0;
2526}
2527
2528/**
2529 * sys_rt_sigprocmask - change the list of currently blocked signals
2530 * @how: whether to add, remove, or set signals
2531 * @nset: stores pending signals
2532 * @oset: previous value of signal mask if non-null
2533 * @sigsetsize: size of sigset_t type
2534 */
2535SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2536 sigset_t __user *, oset, size_t, sigsetsize)
2537{
2538 sigset_t old_set, new_set;
2539 int error;
2540
2541 /* XXX: Don't preclude handling different sized sigset_t's. */
2542 if (sigsetsize != sizeof(sigset_t))
2543 return -EINVAL;
2544
2545 old_set = current->blocked;
2546
2547 if (nset) {
2548 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2549 return -EFAULT;
2550 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2551
2552 error = sigprocmask(how, &new_set, NULL);
2553 if (error)
2554 return error;
2555 }
2556
2557 if (oset) {
2558 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2559 return -EFAULT;
2560 }
2561
2562 return 0;
2563}
2564
2565#ifdef CONFIG_COMPAT
2566COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2567 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2568{
2569#ifdef __BIG_ENDIAN
2570 sigset_t old_set = current->blocked;
2571
2572 /* XXX: Don't preclude handling different sized sigset_t's. */
2573 if (sigsetsize != sizeof(sigset_t))
2574 return -EINVAL;
2575
2576 if (nset) {
2577 compat_sigset_t new32;
2578 sigset_t new_set;
2579 int error;
2580 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2581 return -EFAULT;
2582
2583 sigset_from_compat(&new_set, &new32);
2584 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2585
2586 error = sigprocmask(how, &new_set, NULL);
2587 if (error)
2588 return error;
2589 }
2590 if (oset) {
2591 compat_sigset_t old32;
2592 sigset_to_compat(&old32, &old_set);
2593 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2594 return -EFAULT;
2595 }
2596 return 0;
2597#else
2598 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2599 (sigset_t __user *)oset, sigsetsize);
2600#endif
2601}
2602#endif
2603
2604static int do_sigpending(void *set, unsigned long sigsetsize)
2605{
2606 if (sigsetsize > sizeof(sigset_t))
2607 return -EINVAL;
2608
2609 spin_lock_irq(¤t->sighand->siglock);
2610 sigorsets(set, ¤t->pending.signal,
2611 ¤t->signal->shared_pending.signal);
2612 spin_unlock_irq(¤t->sighand->siglock);
2613
2614 /* Outside the lock because only this thread touches it. */
2615 sigandsets(set, ¤t->blocked, set);
2616 return 0;
2617}
2618
2619/**
2620 * sys_rt_sigpending - examine a pending signal that has been raised
2621 * while blocked
2622 * @uset: stores pending signals
2623 * @sigsetsize: size of sigset_t type or larger
2624 */
2625SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2626{
2627 sigset_t set;
2628 int err = do_sigpending(&set, sigsetsize);
2629 if (!err && copy_to_user(uset, &set, sigsetsize))
2630 err = -EFAULT;
2631 return err;
2632}
2633
2634#ifdef CONFIG_COMPAT
2635COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2636 compat_size_t, sigsetsize)
2637{
2638#ifdef __BIG_ENDIAN
2639 sigset_t set;
2640 int err = do_sigpending(&set, sigsetsize);
2641 if (!err) {
2642 compat_sigset_t set32;
2643 sigset_to_compat(&set32, &set);
2644 /* we can get here only if sigsetsize <= sizeof(set) */
2645 if (copy_to_user(uset, &set32, sigsetsize))
2646 err = -EFAULT;
2647 }
2648 return err;
2649#else
2650 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2651#endif
2652}
2653#endif
2654
2655#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2656
2657int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2658{
2659 int err;
2660
2661 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2662 return -EFAULT;
2663 if (from->si_code < 0)
2664 return __copy_to_user(to, from, sizeof(siginfo_t))
2665 ? -EFAULT : 0;
2666 /*
2667 * If you change siginfo_t structure, please be sure
2668 * this code is fixed accordingly.
2669 * Please remember to update the signalfd_copyinfo() function
2670 * inside fs/signalfd.c too, in case siginfo_t changes.
2671 * It should never copy any pad contained in the structure
2672 * to avoid security leaks, but must copy the generic
2673 * 3 ints plus the relevant union member.
2674 */
2675 err = __put_user(from->si_signo, &to->si_signo);
2676 err |= __put_user(from->si_errno, &to->si_errno);
2677 err |= __put_user((short)from->si_code, &to->si_code);
2678 switch (from->si_code & __SI_MASK) {
2679 case __SI_KILL:
2680 err |= __put_user(from->si_pid, &to->si_pid);
2681 err |= __put_user(from->si_uid, &to->si_uid);
2682 break;
2683 case __SI_TIMER:
2684 err |= __put_user(from->si_tid, &to->si_tid);
2685 err |= __put_user(from->si_overrun, &to->si_overrun);
2686 err |= __put_user(from->si_ptr, &to->si_ptr);
2687 break;
2688 case __SI_POLL:
2689 err |= __put_user(from->si_band, &to->si_band);
2690 err |= __put_user(from->si_fd, &to->si_fd);
2691 break;
2692 case __SI_FAULT:
2693 err |= __put_user(from->si_addr, &to->si_addr);
2694#ifdef __ARCH_SI_TRAPNO
2695 err |= __put_user(from->si_trapno, &to->si_trapno);
2696#endif
2697#ifdef BUS_MCEERR_AO
2698 /*
2699 * Other callers might not initialize the si_lsb field,
2700 * so check explicitly for the right codes here.
2701 */
2702 if (from->si_signo == SIGBUS &&
2703 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2704 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2705#endif
2706#ifdef SEGV_BNDERR
2707 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2708 err |= __put_user(from->si_lower, &to->si_lower);
2709 err |= __put_user(from->si_upper, &to->si_upper);
2710 }
2711#endif
2712#ifdef SEGV_PKUERR
2713 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2714 err |= __put_user(from->si_pkey, &to->si_pkey);
2715#endif
2716 break;
2717 case __SI_CHLD:
2718 err |= __put_user(from->si_pid, &to->si_pid);
2719 err |= __put_user(from->si_uid, &to->si_uid);
2720 err |= __put_user(from->si_status, &to->si_status);
2721 err |= __put_user(from->si_utime, &to->si_utime);
2722 err |= __put_user(from->si_stime, &to->si_stime);
2723 break;
2724 case __SI_RT: /* This is not generated by the kernel as of now. */
2725 case __SI_MESGQ: /* But this is */
2726 err |= __put_user(from->si_pid, &to->si_pid);
2727 err |= __put_user(from->si_uid, &to->si_uid);
2728 err |= __put_user(from->si_ptr, &to->si_ptr);
2729 break;
2730#ifdef __ARCH_SIGSYS
2731 case __SI_SYS:
2732 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2733 err |= __put_user(from->si_syscall, &to->si_syscall);
2734 err |= __put_user(from->si_arch, &to->si_arch);
2735 break;
2736#endif
2737 default: /* this is just in case for now ... */
2738 err |= __put_user(from->si_pid, &to->si_pid);
2739 err |= __put_user(from->si_uid, &to->si_uid);
2740 break;
2741 }
2742 return err;
2743}
2744
2745#endif
2746
2747/**
2748 * do_sigtimedwait - wait for queued signals specified in @which
2749 * @which: queued signals to wait for
2750 * @info: if non-null, the signal's siginfo is returned here
2751 * @ts: upper bound on process time suspension
2752 */
2753int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2754 const struct timespec *ts)
2755{
2756 struct task_struct *tsk = current;
2757 long timeout = MAX_SCHEDULE_TIMEOUT;
2758 sigset_t mask = *which;
2759 int sig;
2760
2761 if (ts) {
2762 if (!timespec_valid(ts))
2763 return -EINVAL;
2764 timeout = timespec_to_jiffies(ts);
2765 /*
2766 * We can be close to the next tick, add another one
2767 * to ensure we will wait at least the time asked for.
2768 */
2769 if (ts->tv_sec || ts->tv_nsec)
2770 timeout++;
2771 }
2772
2773 /*
2774 * Invert the set of allowed signals to get those we want to block.
2775 */
2776 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2777 signotset(&mask);
2778
2779 spin_lock_irq(&tsk->sighand->siglock);
2780 sig = dequeue_signal(tsk, &mask, info);
2781 if (!sig && timeout) {
2782 /*
2783 * None ready, temporarily unblock those we're interested
2784 * while we are sleeping in so that we'll be awakened when
2785 * they arrive. Unblocking is always fine, we can avoid
2786 * set_current_blocked().
2787 */
2788 tsk->real_blocked = tsk->blocked;
2789 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2790 recalc_sigpending();
2791 spin_unlock_irq(&tsk->sighand->siglock);
2792
2793 timeout = freezable_schedule_timeout_interruptible(timeout);
2794
2795 spin_lock_irq(&tsk->sighand->siglock);
2796 __set_task_blocked(tsk, &tsk->real_blocked);
2797 sigemptyset(&tsk->real_blocked);
2798 sig = dequeue_signal(tsk, &mask, info);
2799 }
2800 spin_unlock_irq(&tsk->sighand->siglock);
2801
2802 if (sig)
2803 return sig;
2804 return timeout ? -EINTR : -EAGAIN;
2805}
2806
2807/**
2808 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2809 * in @uthese
2810 * @uthese: queued signals to wait for
2811 * @uinfo: if non-null, the signal's siginfo is returned here
2812 * @uts: upper bound on process time suspension
2813 * @sigsetsize: size of sigset_t type
2814 */
2815SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2816 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2817 size_t, sigsetsize)
2818{
2819 sigset_t these;
2820 struct timespec ts;
2821 siginfo_t info;
2822 int ret;
2823
2824 /* XXX: Don't preclude handling different sized sigset_t's. */
2825 if (sigsetsize != sizeof(sigset_t))
2826 return -EINVAL;
2827
2828 if (copy_from_user(&these, uthese, sizeof(these)))
2829 return -EFAULT;
2830
2831 if (uts) {
2832 if (copy_from_user(&ts, uts, sizeof(ts)))
2833 return -EFAULT;
2834 }
2835
2836 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2837
2838 if (ret > 0 && uinfo) {
2839 if (copy_siginfo_to_user(uinfo, &info))
2840 ret = -EFAULT;
2841 }
2842
2843 return ret;
2844}
2845
2846/**
2847 * sys_kill - send a signal to a process
2848 * @pid: the PID of the process
2849 * @sig: signal to be sent
2850 */
2851SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2852{
2853 struct siginfo info;
2854
2855 info.si_signo = sig;
2856 info.si_errno = 0;
2857 info.si_code = SI_USER;
2858 info.si_pid = task_tgid_vnr(current);
2859 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2860
2861 return kill_something_info(sig, &info, pid);
2862}
2863
2864static int
2865do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2866{
2867 struct task_struct *p;
2868 int error = -ESRCH;
2869
2870 rcu_read_lock();
2871 p = find_task_by_vpid(pid);
2872 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2873 error = check_kill_permission(sig, info, p);
2874 /*
2875 * The null signal is a permissions and process existence
2876 * probe. No signal is actually delivered.
2877 */
2878 if (!error && sig) {
2879 error = do_send_sig_info(sig, info, p, false);
2880 /*
2881 * If lock_task_sighand() failed we pretend the task
2882 * dies after receiving the signal. The window is tiny,
2883 * and the signal is private anyway.
2884 */
2885 if (unlikely(error == -ESRCH))
2886 error = 0;
2887 }
2888 }
2889 rcu_read_unlock();
2890
2891 return error;
2892}
2893
2894static int do_tkill(pid_t tgid, pid_t pid, int sig)
2895{
2896 struct siginfo info = {};
2897
2898 info.si_signo = sig;
2899 info.si_errno = 0;
2900 info.si_code = SI_TKILL;
2901 info.si_pid = task_tgid_vnr(current);
2902 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2903
2904 return do_send_specific(tgid, pid, sig, &info);
2905}
2906
2907/**
2908 * sys_tgkill - send signal to one specific thread
2909 * @tgid: the thread group ID of the thread
2910 * @pid: the PID of the thread
2911 * @sig: signal to be sent
2912 *
2913 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2914 * exists but it's not belonging to the target process anymore. This
2915 * method solves the problem of threads exiting and PIDs getting reused.
2916 */
2917SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2918{
2919 /* This is only valid for single tasks */
2920 if (pid <= 0 || tgid <= 0)
2921 return -EINVAL;
2922
2923 return do_tkill(tgid, pid, sig);
2924}
2925
2926/**
2927 * sys_tkill - send signal to one specific task
2928 * @pid: the PID of the task
2929 * @sig: signal to be sent
2930 *
2931 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2932 */
2933SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2934{
2935 /* This is only valid for single tasks */
2936 if (pid <= 0)
2937 return -EINVAL;
2938
2939 return do_tkill(0, pid, sig);
2940}
2941
2942static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2943{
2944 /* Not even root can pretend to send signals from the kernel.
2945 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2946 */
2947 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2948 (task_pid_vnr(current) != pid))
2949 return -EPERM;
2950
2951 info->si_signo = sig;
2952
2953 /* POSIX.1b doesn't mention process groups. */
2954 return kill_proc_info(sig, info, pid);
2955}
2956
2957/**
2958 * sys_rt_sigqueueinfo - send signal information to a signal
2959 * @pid: the PID of the thread
2960 * @sig: signal to be sent
2961 * @uinfo: signal info to be sent
2962 */
2963SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2964 siginfo_t __user *, uinfo)
2965{
2966 siginfo_t info;
2967 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2968 return -EFAULT;
2969 return do_rt_sigqueueinfo(pid, sig, &info);
2970}
2971
2972#ifdef CONFIG_COMPAT
2973COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
2974 compat_pid_t, pid,
2975 int, sig,
2976 struct compat_siginfo __user *, uinfo)
2977{
2978 siginfo_t info = {};
2979 int ret = copy_siginfo_from_user32(&info, uinfo);
2980 if (unlikely(ret))
2981 return ret;
2982 return do_rt_sigqueueinfo(pid, sig, &info);
2983}
2984#endif
2985
2986static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2987{
2988 /* This is only valid for single tasks */
2989 if (pid <= 0 || tgid <= 0)
2990 return -EINVAL;
2991
2992 /* Not even root can pretend to send signals from the kernel.
2993 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2994 */
2995 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2996 (task_pid_vnr(current) != pid))
2997 return -EPERM;
2998
2999 info->si_signo = sig;
3000
3001 return do_send_specific(tgid, pid, sig, info);
3002}
3003
3004SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3005 siginfo_t __user *, uinfo)
3006{
3007 siginfo_t info;
3008
3009 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3010 return -EFAULT;
3011
3012 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3013}
3014
3015#ifdef CONFIG_COMPAT
3016COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3017 compat_pid_t, tgid,
3018 compat_pid_t, pid,
3019 int, sig,
3020 struct compat_siginfo __user *, uinfo)
3021{
3022 siginfo_t info = {};
3023
3024 if (copy_siginfo_from_user32(&info, uinfo))
3025 return -EFAULT;
3026 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3027}
3028#endif
3029
3030/*
3031 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3032 */
3033void kernel_sigaction(int sig, __sighandler_t action)
3034{
3035 spin_lock_irq(¤t->sighand->siglock);
3036 current->sighand->action[sig - 1].sa.sa_handler = action;
3037 if (action == SIG_IGN) {
3038 sigset_t mask;
3039
3040 sigemptyset(&mask);
3041 sigaddset(&mask, sig);
3042
3043 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3044 flush_sigqueue_mask(&mask, ¤t->pending);
3045 recalc_sigpending();
3046 }
3047 spin_unlock_irq(¤t->sighand->siglock);
3048}
3049EXPORT_SYMBOL(kernel_sigaction);
3050
3051int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3052{
3053 struct task_struct *p = current, *t;
3054 struct k_sigaction *k;
3055 sigset_t mask;
3056
3057 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3058 return -EINVAL;
3059
3060 k = &p->sighand->action[sig-1];
3061
3062 spin_lock_irq(&p->sighand->siglock);
3063 if (oact)
3064 *oact = *k;
3065
3066 if (act) {
3067 sigdelsetmask(&act->sa.sa_mask,
3068 sigmask(SIGKILL) | sigmask(SIGSTOP));
3069 *k = *act;
3070 /*
3071 * POSIX 3.3.1.3:
3072 * "Setting a signal action to SIG_IGN for a signal that is
3073 * pending shall cause the pending signal to be discarded,
3074 * whether or not it is blocked."
3075 *
3076 * "Setting a signal action to SIG_DFL for a signal that is
3077 * pending and whose default action is to ignore the signal
3078 * (for example, SIGCHLD), shall cause the pending signal to
3079 * be discarded, whether or not it is blocked"
3080 */
3081 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3082 sigemptyset(&mask);
3083 sigaddset(&mask, sig);
3084 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3085 for_each_thread(p, t)
3086 flush_sigqueue_mask(&mask, &t->pending);
3087 }
3088 }
3089
3090 spin_unlock_irq(&p->sighand->siglock);
3091 return 0;
3092}
3093
3094static int
3095do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3096{
3097 stack_t oss;
3098 int error;
3099
3100 oss.ss_sp = (void __user *) current->sas_ss_sp;
3101 oss.ss_size = current->sas_ss_size;
3102 oss.ss_flags = sas_ss_flags(sp);
3103
3104 if (uss) {
3105 void __user *ss_sp;
3106 size_t ss_size;
3107 int ss_flags;
3108
3109 error = -EFAULT;
3110 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3111 goto out;
3112 error = __get_user(ss_sp, &uss->ss_sp) |
3113 __get_user(ss_flags, &uss->ss_flags) |
3114 __get_user(ss_size, &uss->ss_size);
3115 if (error)
3116 goto out;
3117
3118 error = -EPERM;
3119 if (on_sig_stack(sp))
3120 goto out;
3121
3122 error = -EINVAL;
3123 /*
3124 * Note - this code used to test ss_flags incorrectly:
3125 * old code may have been written using ss_flags==0
3126 * to mean ss_flags==SS_ONSTACK (as this was the only
3127 * way that worked) - this fix preserves that older
3128 * mechanism.
3129 */
3130 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3131 goto out;
3132
3133 if (ss_flags == SS_DISABLE) {
3134 ss_size = 0;
3135 ss_sp = NULL;
3136 } else {
3137 error = -ENOMEM;
3138 if (ss_size < MINSIGSTKSZ)
3139 goto out;
3140 }
3141
3142 current->sas_ss_sp = (unsigned long) ss_sp;
3143 current->sas_ss_size = ss_size;
3144 }
3145
3146 error = 0;
3147 if (uoss) {
3148 error = -EFAULT;
3149 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3150 goto out;
3151 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3152 __put_user(oss.ss_size, &uoss->ss_size) |
3153 __put_user(oss.ss_flags, &uoss->ss_flags);
3154 }
3155
3156out:
3157 return error;
3158}
3159SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3160{
3161 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3162}
3163
3164int restore_altstack(const stack_t __user *uss)
3165{
3166 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3167 /* squash all but EFAULT for now */
3168 return err == -EFAULT ? err : 0;
3169}
3170
3171int __save_altstack(stack_t __user *uss, unsigned long sp)
3172{
3173 struct task_struct *t = current;
3174 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3175 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3176 __put_user(t->sas_ss_size, &uss->ss_size);
3177}
3178
3179#ifdef CONFIG_COMPAT
3180COMPAT_SYSCALL_DEFINE2(sigaltstack,
3181 const compat_stack_t __user *, uss_ptr,
3182 compat_stack_t __user *, uoss_ptr)
3183{
3184 stack_t uss, uoss;
3185 int ret;
3186 mm_segment_t seg;
3187
3188 if (uss_ptr) {
3189 compat_stack_t uss32;
3190
3191 memset(&uss, 0, sizeof(stack_t));
3192 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3193 return -EFAULT;
3194 uss.ss_sp = compat_ptr(uss32.ss_sp);
3195 uss.ss_flags = uss32.ss_flags;
3196 uss.ss_size = uss32.ss_size;
3197 }
3198 seg = get_fs();
3199 set_fs(KERNEL_DS);
3200 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3201 (stack_t __force __user *) &uoss,
3202 compat_user_stack_pointer());
3203 set_fs(seg);
3204 if (ret >= 0 && uoss_ptr) {
3205 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3206 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3207 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3208 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3209 ret = -EFAULT;
3210 }
3211 return ret;
3212}
3213
3214int compat_restore_altstack(const compat_stack_t __user *uss)
3215{
3216 int err = compat_sys_sigaltstack(uss, NULL);
3217 /* squash all but -EFAULT for now */
3218 return err == -EFAULT ? err : 0;
3219}
3220
3221int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3222{
3223 struct task_struct *t = current;
3224 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3225 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3226 __put_user(t->sas_ss_size, &uss->ss_size);
3227}
3228#endif
3229
3230#ifdef __ARCH_WANT_SYS_SIGPENDING
3231
3232/**
3233 * sys_sigpending - examine pending signals
3234 * @set: where mask of pending signal is returned
3235 */
3236SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3237{
3238 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3239}
3240
3241#endif
3242
3243#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3244/**
3245 * sys_sigprocmask - examine and change blocked signals
3246 * @how: whether to add, remove, or set signals
3247 * @nset: signals to add or remove (if non-null)
3248 * @oset: previous value of signal mask if non-null
3249 *
3250 * Some platforms have their own version with special arguments;
3251 * others support only sys_rt_sigprocmask.
3252 */
3253
3254SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3255 old_sigset_t __user *, oset)
3256{
3257 old_sigset_t old_set, new_set;
3258 sigset_t new_blocked;
3259
3260 old_set = current->blocked.sig[0];
3261
3262 if (nset) {
3263 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3264 return -EFAULT;
3265
3266 new_blocked = current->blocked;
3267
3268 switch (how) {
3269 case SIG_BLOCK:
3270 sigaddsetmask(&new_blocked, new_set);
3271 break;
3272 case SIG_UNBLOCK:
3273 sigdelsetmask(&new_blocked, new_set);
3274 break;
3275 case SIG_SETMASK:
3276 new_blocked.sig[0] = new_set;
3277 break;
3278 default:
3279 return -EINVAL;
3280 }
3281
3282 set_current_blocked(&new_blocked);
3283 }
3284
3285 if (oset) {
3286 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3287 return -EFAULT;
3288 }
3289
3290 return 0;
3291}
3292#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3293
3294#ifndef CONFIG_ODD_RT_SIGACTION
3295/**
3296 * sys_rt_sigaction - alter an action taken by a process
3297 * @sig: signal to be sent
3298 * @act: new sigaction
3299 * @oact: used to save the previous sigaction
3300 * @sigsetsize: size of sigset_t type
3301 */
3302SYSCALL_DEFINE4(rt_sigaction, int, sig,
3303 const struct sigaction __user *, act,
3304 struct sigaction __user *, oact,
3305 size_t, sigsetsize)
3306{
3307 struct k_sigaction new_sa, old_sa;
3308 int ret = -EINVAL;
3309
3310 /* XXX: Don't preclude handling different sized sigset_t's. */
3311 if (sigsetsize != sizeof(sigset_t))
3312 goto out;
3313
3314 if (act) {
3315 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3316 return -EFAULT;
3317 }
3318
3319 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3320
3321 if (!ret && oact) {
3322 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3323 return -EFAULT;
3324 }
3325out:
3326 return ret;
3327}
3328#ifdef CONFIG_COMPAT
3329COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3330 const struct compat_sigaction __user *, act,
3331 struct compat_sigaction __user *, oact,
3332 compat_size_t, sigsetsize)
3333{
3334 struct k_sigaction new_ka, old_ka;
3335 compat_sigset_t mask;
3336#ifdef __ARCH_HAS_SA_RESTORER
3337 compat_uptr_t restorer;
3338#endif
3339 int ret;
3340
3341 /* XXX: Don't preclude handling different sized sigset_t's. */
3342 if (sigsetsize != sizeof(compat_sigset_t))
3343 return -EINVAL;
3344
3345 if (act) {
3346 compat_uptr_t handler;
3347 ret = get_user(handler, &act->sa_handler);
3348 new_ka.sa.sa_handler = compat_ptr(handler);
3349#ifdef __ARCH_HAS_SA_RESTORER
3350 ret |= get_user(restorer, &act->sa_restorer);
3351 new_ka.sa.sa_restorer = compat_ptr(restorer);
3352#endif
3353 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3354 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3355 if (ret)
3356 return -EFAULT;
3357 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3358 }
3359
3360 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3361 if (!ret && oact) {
3362 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3363 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3364 &oact->sa_handler);
3365 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3366 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3367#ifdef __ARCH_HAS_SA_RESTORER
3368 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3369 &oact->sa_restorer);
3370#endif
3371 }
3372 return ret;
3373}
3374#endif
3375#endif /* !CONFIG_ODD_RT_SIGACTION */
3376
3377#ifdef CONFIG_OLD_SIGACTION
3378SYSCALL_DEFINE3(sigaction, int, sig,
3379 const struct old_sigaction __user *, act,
3380 struct old_sigaction __user *, oact)
3381{
3382 struct k_sigaction new_ka, old_ka;
3383 int ret;
3384
3385 if (act) {
3386 old_sigset_t mask;
3387 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3388 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3389 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3390 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3391 __get_user(mask, &act->sa_mask))
3392 return -EFAULT;
3393#ifdef __ARCH_HAS_KA_RESTORER
3394 new_ka.ka_restorer = NULL;
3395#endif
3396 siginitset(&new_ka.sa.sa_mask, mask);
3397 }
3398
3399 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3400
3401 if (!ret && oact) {
3402 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3403 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3404 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3405 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3406 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3407 return -EFAULT;
3408 }
3409
3410 return ret;
3411}
3412#endif
3413#ifdef CONFIG_COMPAT_OLD_SIGACTION
3414COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3415 const struct compat_old_sigaction __user *, act,
3416 struct compat_old_sigaction __user *, oact)
3417{
3418 struct k_sigaction new_ka, old_ka;
3419 int ret;
3420 compat_old_sigset_t mask;
3421 compat_uptr_t handler, restorer;
3422
3423 if (act) {
3424 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3425 __get_user(handler, &act->sa_handler) ||
3426 __get_user(restorer, &act->sa_restorer) ||
3427 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3428 __get_user(mask, &act->sa_mask))
3429 return -EFAULT;
3430
3431#ifdef __ARCH_HAS_KA_RESTORER
3432 new_ka.ka_restorer = NULL;
3433#endif
3434 new_ka.sa.sa_handler = compat_ptr(handler);
3435 new_ka.sa.sa_restorer = compat_ptr(restorer);
3436 siginitset(&new_ka.sa.sa_mask, mask);
3437 }
3438
3439 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3440
3441 if (!ret && oact) {
3442 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3443 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3444 &oact->sa_handler) ||
3445 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3446 &oact->sa_restorer) ||
3447 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3448 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3449 return -EFAULT;
3450 }
3451 return ret;
3452}
3453#endif
3454
3455#ifdef CONFIG_SGETMASK_SYSCALL
3456
3457/*
3458 * For backwards compatibility. Functionality superseded by sigprocmask.
3459 */
3460SYSCALL_DEFINE0(sgetmask)
3461{
3462 /* SMP safe */
3463 return current->blocked.sig[0];
3464}
3465
3466SYSCALL_DEFINE1(ssetmask, int, newmask)
3467{
3468 int old = current->blocked.sig[0];
3469 sigset_t newset;
3470
3471 siginitset(&newset, newmask);
3472 set_current_blocked(&newset);
3473
3474 return old;
3475}
3476#endif /* CONFIG_SGETMASK_SYSCALL */
3477
3478#ifdef __ARCH_WANT_SYS_SIGNAL
3479/*
3480 * For backwards compatibility. Functionality superseded by sigaction.
3481 */
3482SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3483{
3484 struct k_sigaction new_sa, old_sa;
3485 int ret;
3486
3487 new_sa.sa.sa_handler = handler;
3488 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3489 sigemptyset(&new_sa.sa.sa_mask);
3490
3491 ret = do_sigaction(sig, &new_sa, &old_sa);
3492
3493 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3494}
3495#endif /* __ARCH_WANT_SYS_SIGNAL */
3496
3497#ifdef __ARCH_WANT_SYS_PAUSE
3498
3499SYSCALL_DEFINE0(pause)
3500{
3501 while (!signal_pending(current)) {
3502 __set_current_state(TASK_INTERRUPTIBLE);
3503 schedule();
3504 }
3505 return -ERESTARTNOHAND;
3506}
3507
3508#endif
3509
3510static int sigsuspend(sigset_t *set)
3511{
3512 current->saved_sigmask = current->blocked;
3513 set_current_blocked(set);
3514
3515 while (!signal_pending(current)) {
3516 __set_current_state(TASK_INTERRUPTIBLE);
3517 schedule();
3518 }
3519 set_restore_sigmask();
3520 return -ERESTARTNOHAND;
3521}
3522
3523/**
3524 * sys_rt_sigsuspend - replace the signal mask for a value with the
3525 * @unewset value until a signal is received
3526 * @unewset: new signal mask value
3527 * @sigsetsize: size of sigset_t type
3528 */
3529SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3530{
3531 sigset_t newset;
3532
3533 /* XXX: Don't preclude handling different sized sigset_t's. */
3534 if (sigsetsize != sizeof(sigset_t))
3535 return -EINVAL;
3536
3537 if (copy_from_user(&newset, unewset, sizeof(newset)))
3538 return -EFAULT;
3539 return sigsuspend(&newset);
3540}
3541
3542#ifdef CONFIG_COMPAT
3543COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3544{
3545#ifdef __BIG_ENDIAN
3546 sigset_t newset;
3547 compat_sigset_t newset32;
3548
3549 /* XXX: Don't preclude handling different sized sigset_t's. */
3550 if (sigsetsize != sizeof(sigset_t))
3551 return -EINVAL;
3552
3553 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3554 return -EFAULT;
3555 sigset_from_compat(&newset, &newset32);
3556 return sigsuspend(&newset);
3557#else
3558 /* on little-endian bitmaps don't care about granularity */
3559 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3560#endif
3561}
3562#endif
3563
3564#ifdef CONFIG_OLD_SIGSUSPEND
3565SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3566{
3567 sigset_t blocked;
3568 siginitset(&blocked, mask);
3569 return sigsuspend(&blocked);
3570}
3571#endif
3572#ifdef CONFIG_OLD_SIGSUSPEND3
3573SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3574{
3575 sigset_t blocked;
3576 siginitset(&blocked, mask);
3577 return sigsuspend(&blocked);
3578}
3579#endif
3580
3581__weak const char *arch_vma_name(struct vm_area_struct *vma)
3582{
3583 return NULL;
3584}
3585
3586void __init signals_init(void)
3587{
3588 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3589 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3590 != offsetof(struct siginfo, _sifields._pad));
3591
3592 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3593}
3594
3595#ifdef CONFIG_KGDB_KDB
3596#include <linux/kdb.h>
3597/*
3598 * kdb_send_sig_info - Allows kdb to send signals without exposing
3599 * signal internals. This function checks if the required locks are
3600 * available before calling the main signal code, to avoid kdb
3601 * deadlocks.
3602 */
3603void
3604kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3605{
3606 static struct task_struct *kdb_prev_t;
3607 int sig, new_t;
3608 if (!spin_trylock(&t->sighand->siglock)) {
3609 kdb_printf("Can't do kill command now.\n"
3610 "The sigmask lock is held somewhere else in "
3611 "kernel, try again later\n");
3612 return;
3613 }
3614 spin_unlock(&t->sighand->siglock);
3615 new_t = kdb_prev_t != t;
3616 kdb_prev_t = t;
3617 if (t->state != TASK_RUNNING && new_t) {
3618 kdb_printf("Process is not RUNNING, sending a signal from "
3619 "kdb risks deadlock\n"
3620 "on the run queue locks. "
3621 "The signal has _not_ been sent.\n"
3622 "Reissue the kill command if you want to risk "
3623 "the deadlock.\n");
3624 return;
3625 }
3626 sig = info->si_signo;
3627 if (send_sig_info(sig, info, t))
3628 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3629 sig, t->pid);
3630 else
3631 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3632}
3633#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/security.h>
21#include <linux/syscalls.h>
22#include <linux/ptrace.h>
23#include <linux/signal.h>
24#include <linux/signalfd.h>
25#include <linux/ratelimit.h>
26#include <linux/tracehook.h>
27#include <linux/capability.h>
28#include <linux/freezer.h>
29#include <linux/pid_namespace.h>
30#include <linux/nsproxy.h>
31#include <linux/user_namespace.h>
32#include <linux/uprobes.h>
33#define CREATE_TRACE_POINTS
34#include <trace/events/signal.h>
35
36#include <asm/param.h>
37#include <asm/uaccess.h>
38#include <asm/unistd.h>
39#include <asm/siginfo.h>
40#include <asm/cacheflush.h>
41#include "audit.h" /* audit_signal_info() */
42
43/*
44 * SLAB caches for signal bits.
45 */
46
47static struct kmem_cache *sigqueue_cachep;
48
49int print_fatal_signals __read_mostly;
50
51static void __user *sig_handler(struct task_struct *t, int sig)
52{
53 return t->sighand->action[sig - 1].sa.sa_handler;
54}
55
56static int sig_handler_ignored(void __user *handler, int sig)
57{
58 /* Is it explicitly or implicitly ignored? */
59 return handler == SIG_IGN ||
60 (handler == SIG_DFL && sig_kernel_ignore(sig));
61}
62
63static int sig_task_ignored(struct task_struct *t, int sig, bool force)
64{
65 void __user *handler;
66
67 handler = sig_handler(t, sig);
68
69 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
70 handler == SIG_DFL && !force)
71 return 1;
72
73 return sig_handler_ignored(handler, sig);
74}
75
76static int sig_ignored(struct task_struct *t, int sig, bool force)
77{
78 /*
79 * Blocked signals are never ignored, since the
80 * signal handler may change by the time it is
81 * unblocked.
82 */
83 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
84 return 0;
85
86 if (!sig_task_ignored(t, sig, force))
87 return 0;
88
89 /*
90 * Tracers may want to know about even ignored signals.
91 */
92 return !t->ptrace;
93}
94
95/*
96 * Re-calculate pending state from the set of locally pending
97 * signals, globally pending signals, and blocked signals.
98 */
99static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
100{
101 unsigned long ready;
102 long i;
103
104 switch (_NSIG_WORDS) {
105 default:
106 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
107 ready |= signal->sig[i] &~ blocked->sig[i];
108 break;
109
110 case 4: ready = signal->sig[3] &~ blocked->sig[3];
111 ready |= signal->sig[2] &~ blocked->sig[2];
112 ready |= signal->sig[1] &~ blocked->sig[1];
113 ready |= signal->sig[0] &~ blocked->sig[0];
114 break;
115
116 case 2: ready = signal->sig[1] &~ blocked->sig[1];
117 ready |= signal->sig[0] &~ blocked->sig[0];
118 break;
119
120 case 1: ready = signal->sig[0] &~ blocked->sig[0];
121 }
122 return ready != 0;
123}
124
125#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
126
127static int recalc_sigpending_tsk(struct task_struct *t)
128{
129 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
130 PENDING(&t->pending, &t->blocked) ||
131 PENDING(&t->signal->shared_pending, &t->blocked)) {
132 set_tsk_thread_flag(t, TIF_SIGPENDING);
133 return 1;
134 }
135 /*
136 * We must never clear the flag in another thread, or in current
137 * when it's possible the current syscall is returning -ERESTART*.
138 * So we don't clear it here, and only callers who know they should do.
139 */
140 return 0;
141}
142
143/*
144 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
145 * This is superfluous when called on current, the wakeup is a harmless no-op.
146 */
147void recalc_sigpending_and_wake(struct task_struct *t)
148{
149 if (recalc_sigpending_tsk(t))
150 signal_wake_up(t, 0);
151}
152
153void recalc_sigpending(void)
154{
155 if (!recalc_sigpending_tsk(current) && !freezing(current))
156 clear_thread_flag(TIF_SIGPENDING);
157
158}
159
160/* Given the mask, find the first available signal that should be serviced. */
161
162#define SYNCHRONOUS_MASK \
163 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
164 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
165
166int next_signal(struct sigpending *pending, sigset_t *mask)
167{
168 unsigned long i, *s, *m, x;
169 int sig = 0;
170
171 s = pending->signal.sig;
172 m = mask->sig;
173
174 /*
175 * Handle the first word specially: it contains the
176 * synchronous signals that need to be dequeued first.
177 */
178 x = *s &~ *m;
179 if (x) {
180 if (x & SYNCHRONOUS_MASK)
181 x &= SYNCHRONOUS_MASK;
182 sig = ffz(~x) + 1;
183 return sig;
184 }
185
186 switch (_NSIG_WORDS) {
187 default:
188 for (i = 1; i < _NSIG_WORDS; ++i) {
189 x = *++s &~ *++m;
190 if (!x)
191 continue;
192 sig = ffz(~x) + i*_NSIG_BPW + 1;
193 break;
194 }
195 break;
196
197 case 2:
198 x = s[1] &~ m[1];
199 if (!x)
200 break;
201 sig = ffz(~x) + _NSIG_BPW + 1;
202 break;
203
204 case 1:
205 /* Nothing to do */
206 break;
207 }
208
209 return sig;
210}
211
212static inline void print_dropped_signal(int sig)
213{
214 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
215
216 if (!print_fatal_signals)
217 return;
218
219 if (!__ratelimit(&ratelimit_state))
220 return;
221
222 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
223 current->comm, current->pid, sig);
224}
225
226/**
227 * task_set_jobctl_pending - set jobctl pending bits
228 * @task: target task
229 * @mask: pending bits to set
230 *
231 * Clear @mask from @task->jobctl. @mask must be subset of
232 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
233 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
234 * cleared. If @task is already being killed or exiting, this function
235 * becomes noop.
236 *
237 * CONTEXT:
238 * Must be called with @task->sighand->siglock held.
239 *
240 * RETURNS:
241 * %true if @mask is set, %false if made noop because @task was dying.
242 */
243bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
244{
245 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
246 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
247 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
248
249 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
250 return false;
251
252 if (mask & JOBCTL_STOP_SIGMASK)
253 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
254
255 task->jobctl |= mask;
256 return true;
257}
258
259/**
260 * task_clear_jobctl_trapping - clear jobctl trapping bit
261 * @task: target task
262 *
263 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
264 * Clear it and wake up the ptracer. Note that we don't need any further
265 * locking. @task->siglock guarantees that @task->parent points to the
266 * ptracer.
267 *
268 * CONTEXT:
269 * Must be called with @task->sighand->siglock held.
270 */
271void task_clear_jobctl_trapping(struct task_struct *task)
272{
273 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
274 task->jobctl &= ~JOBCTL_TRAPPING;
275 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
276 }
277}
278
279/**
280 * task_clear_jobctl_pending - clear jobctl pending bits
281 * @task: target task
282 * @mask: pending bits to clear
283 *
284 * Clear @mask from @task->jobctl. @mask must be subset of
285 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
286 * STOP bits are cleared together.
287 *
288 * If clearing of @mask leaves no stop or trap pending, this function calls
289 * task_clear_jobctl_trapping().
290 *
291 * CONTEXT:
292 * Must be called with @task->sighand->siglock held.
293 */
294void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
295{
296 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
297
298 if (mask & JOBCTL_STOP_PENDING)
299 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
300
301 task->jobctl &= ~mask;
302
303 if (!(task->jobctl & JOBCTL_PENDING_MASK))
304 task_clear_jobctl_trapping(task);
305}
306
307/**
308 * task_participate_group_stop - participate in a group stop
309 * @task: task participating in a group stop
310 *
311 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
312 * Group stop states are cleared and the group stop count is consumed if
313 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
314 * stop, the appropriate %SIGNAL_* flags are set.
315 *
316 * CONTEXT:
317 * Must be called with @task->sighand->siglock held.
318 *
319 * RETURNS:
320 * %true if group stop completion should be notified to the parent, %false
321 * otherwise.
322 */
323static bool task_participate_group_stop(struct task_struct *task)
324{
325 struct signal_struct *sig = task->signal;
326 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
327
328 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
329
330 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
331
332 if (!consume)
333 return false;
334
335 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
336 sig->group_stop_count--;
337
338 /*
339 * Tell the caller to notify completion iff we are entering into a
340 * fresh group stop. Read comment in do_signal_stop() for details.
341 */
342 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
343 sig->flags = SIGNAL_STOP_STOPPED;
344 return true;
345 }
346 return false;
347}
348
349/*
350 * allocate a new signal queue record
351 * - this may be called without locks if and only if t == current, otherwise an
352 * appropriate lock must be held to stop the target task from exiting
353 */
354static struct sigqueue *
355__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
356{
357 struct sigqueue *q = NULL;
358 struct user_struct *user;
359
360 /*
361 * Protect access to @t credentials. This can go away when all
362 * callers hold rcu read lock.
363 */
364 rcu_read_lock();
365 user = get_uid(__task_cred(t)->user);
366 atomic_inc(&user->sigpending);
367 rcu_read_unlock();
368
369 if (override_rlimit ||
370 atomic_read(&user->sigpending) <=
371 task_rlimit(t, RLIMIT_SIGPENDING)) {
372 q = kmem_cache_alloc(sigqueue_cachep, flags);
373 } else {
374 print_dropped_signal(sig);
375 }
376
377 if (unlikely(q == NULL)) {
378 atomic_dec(&user->sigpending);
379 free_uid(user);
380 } else {
381 INIT_LIST_HEAD(&q->list);
382 q->flags = 0;
383 q->user = user;
384 }
385
386 return q;
387}
388
389static void __sigqueue_free(struct sigqueue *q)
390{
391 if (q->flags & SIGQUEUE_PREALLOC)
392 return;
393 atomic_dec(&q->user->sigpending);
394 free_uid(q->user);
395 kmem_cache_free(sigqueue_cachep, q);
396}
397
398void flush_sigqueue(struct sigpending *queue)
399{
400 struct sigqueue *q;
401
402 sigemptyset(&queue->signal);
403 while (!list_empty(&queue->list)) {
404 q = list_entry(queue->list.next, struct sigqueue , list);
405 list_del_init(&q->list);
406 __sigqueue_free(q);
407 }
408}
409
410/*
411 * Flush all pending signals for a task.
412 */
413void __flush_signals(struct task_struct *t)
414{
415 clear_tsk_thread_flag(t, TIF_SIGPENDING);
416 flush_sigqueue(&t->pending);
417 flush_sigqueue(&t->signal->shared_pending);
418}
419
420void flush_signals(struct task_struct *t)
421{
422 unsigned long flags;
423
424 spin_lock_irqsave(&t->sighand->siglock, flags);
425 __flush_signals(t);
426 spin_unlock_irqrestore(&t->sighand->siglock, flags);
427}
428
429static void __flush_itimer_signals(struct sigpending *pending)
430{
431 sigset_t signal, retain;
432 struct sigqueue *q, *n;
433
434 signal = pending->signal;
435 sigemptyset(&retain);
436
437 list_for_each_entry_safe(q, n, &pending->list, list) {
438 int sig = q->info.si_signo;
439
440 if (likely(q->info.si_code != SI_TIMER)) {
441 sigaddset(&retain, sig);
442 } else {
443 sigdelset(&signal, sig);
444 list_del_init(&q->list);
445 __sigqueue_free(q);
446 }
447 }
448
449 sigorsets(&pending->signal, &signal, &retain);
450}
451
452void flush_itimer_signals(void)
453{
454 struct task_struct *tsk = current;
455 unsigned long flags;
456
457 spin_lock_irqsave(&tsk->sighand->siglock, flags);
458 __flush_itimer_signals(&tsk->pending);
459 __flush_itimer_signals(&tsk->signal->shared_pending);
460 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
461}
462
463void ignore_signals(struct task_struct *t)
464{
465 int i;
466
467 for (i = 0; i < _NSIG; ++i)
468 t->sighand->action[i].sa.sa_handler = SIG_IGN;
469
470 flush_signals(t);
471}
472
473/*
474 * Flush all handlers for a task.
475 */
476
477void
478flush_signal_handlers(struct task_struct *t, int force_default)
479{
480 int i;
481 struct k_sigaction *ka = &t->sighand->action[0];
482 for (i = _NSIG ; i != 0 ; i--) {
483 if (force_default || ka->sa.sa_handler != SIG_IGN)
484 ka->sa.sa_handler = SIG_DFL;
485 ka->sa.sa_flags = 0;
486 sigemptyset(&ka->sa.sa_mask);
487 ka++;
488 }
489}
490
491int unhandled_signal(struct task_struct *tsk, int sig)
492{
493 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
494 if (is_global_init(tsk))
495 return 1;
496 if (handler != SIG_IGN && handler != SIG_DFL)
497 return 0;
498 /* if ptraced, let the tracer determine */
499 return !tsk->ptrace;
500}
501
502/*
503 * Notify the system that a driver wants to block all signals for this
504 * process, and wants to be notified if any signals at all were to be
505 * sent/acted upon. If the notifier routine returns non-zero, then the
506 * signal will be acted upon after all. If the notifier routine returns 0,
507 * then then signal will be blocked. Only one block per process is
508 * allowed. priv is a pointer to private data that the notifier routine
509 * can use to determine if the signal should be blocked or not.
510 */
511void
512block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
513{
514 unsigned long flags;
515
516 spin_lock_irqsave(¤t->sighand->siglock, flags);
517 current->notifier_mask = mask;
518 current->notifier_data = priv;
519 current->notifier = notifier;
520 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
521}
522
523/* Notify the system that blocking has ended. */
524
525void
526unblock_all_signals(void)
527{
528 unsigned long flags;
529
530 spin_lock_irqsave(¤t->sighand->siglock, flags);
531 current->notifier = NULL;
532 current->notifier_data = NULL;
533 recalc_sigpending();
534 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
535}
536
537static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
538{
539 struct sigqueue *q, *first = NULL;
540
541 /*
542 * Collect the siginfo appropriate to this signal. Check if
543 * there is another siginfo for the same signal.
544 */
545 list_for_each_entry(q, &list->list, list) {
546 if (q->info.si_signo == sig) {
547 if (first)
548 goto still_pending;
549 first = q;
550 }
551 }
552
553 sigdelset(&list->signal, sig);
554
555 if (first) {
556still_pending:
557 list_del_init(&first->list);
558 copy_siginfo(info, &first->info);
559 __sigqueue_free(first);
560 } else {
561 /*
562 * Ok, it wasn't in the queue. This must be
563 * a fast-pathed signal or we must have been
564 * out of queue space. So zero out the info.
565 */
566 info->si_signo = sig;
567 info->si_errno = 0;
568 info->si_code = SI_USER;
569 info->si_pid = 0;
570 info->si_uid = 0;
571 }
572}
573
574static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
575 siginfo_t *info)
576{
577 int sig = next_signal(pending, mask);
578
579 if (sig) {
580 if (current->notifier) {
581 if (sigismember(current->notifier_mask, sig)) {
582 if (!(current->notifier)(current->notifier_data)) {
583 clear_thread_flag(TIF_SIGPENDING);
584 return 0;
585 }
586 }
587 }
588
589 collect_signal(sig, pending, info);
590 }
591
592 return sig;
593}
594
595/*
596 * Dequeue a signal and return the element to the caller, which is
597 * expected to free it.
598 *
599 * All callers have to hold the siglock.
600 */
601int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
602{
603 int signr;
604
605 /* We only dequeue private signals from ourselves, we don't let
606 * signalfd steal them
607 */
608 signr = __dequeue_signal(&tsk->pending, mask, info);
609 if (!signr) {
610 signr = __dequeue_signal(&tsk->signal->shared_pending,
611 mask, info);
612 /*
613 * itimer signal ?
614 *
615 * itimers are process shared and we restart periodic
616 * itimers in the signal delivery path to prevent DoS
617 * attacks in the high resolution timer case. This is
618 * compliant with the old way of self-restarting
619 * itimers, as the SIGALRM is a legacy signal and only
620 * queued once. Changing the restart behaviour to
621 * restart the timer in the signal dequeue path is
622 * reducing the timer noise on heavy loaded !highres
623 * systems too.
624 */
625 if (unlikely(signr == SIGALRM)) {
626 struct hrtimer *tmr = &tsk->signal->real_timer;
627
628 if (!hrtimer_is_queued(tmr) &&
629 tsk->signal->it_real_incr.tv64 != 0) {
630 hrtimer_forward(tmr, tmr->base->get_time(),
631 tsk->signal->it_real_incr);
632 hrtimer_restart(tmr);
633 }
634 }
635 }
636
637 recalc_sigpending();
638 if (!signr)
639 return 0;
640
641 if (unlikely(sig_kernel_stop(signr))) {
642 /*
643 * Set a marker that we have dequeued a stop signal. Our
644 * caller might release the siglock and then the pending
645 * stop signal it is about to process is no longer in the
646 * pending bitmasks, but must still be cleared by a SIGCONT
647 * (and overruled by a SIGKILL). So those cases clear this
648 * shared flag after we've set it. Note that this flag may
649 * remain set after the signal we return is ignored or
650 * handled. That doesn't matter because its only purpose
651 * is to alert stop-signal processing code when another
652 * processor has come along and cleared the flag.
653 */
654 current->jobctl |= JOBCTL_STOP_DEQUEUED;
655 }
656 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
657 /*
658 * Release the siglock to ensure proper locking order
659 * of timer locks outside of siglocks. Note, we leave
660 * irqs disabled here, since the posix-timers code is
661 * about to disable them again anyway.
662 */
663 spin_unlock(&tsk->sighand->siglock);
664 do_schedule_next_timer(info);
665 spin_lock(&tsk->sighand->siglock);
666 }
667 return signr;
668}
669
670/*
671 * Tell a process that it has a new active signal..
672 *
673 * NOTE! we rely on the previous spin_lock to
674 * lock interrupts for us! We can only be called with
675 * "siglock" held, and the local interrupt must
676 * have been disabled when that got acquired!
677 *
678 * No need to set need_resched since signal event passing
679 * goes through ->blocked
680 */
681void signal_wake_up(struct task_struct *t, int resume)
682{
683 unsigned int mask;
684
685 set_tsk_thread_flag(t, TIF_SIGPENDING);
686
687 /*
688 * For SIGKILL, we want to wake it up in the stopped/traced/killable
689 * case. We don't check t->state here because there is a race with it
690 * executing another processor and just now entering stopped state.
691 * By using wake_up_state, we ensure the process will wake up and
692 * handle its death signal.
693 */
694 mask = TASK_INTERRUPTIBLE;
695 if (resume)
696 mask |= TASK_WAKEKILL;
697 if (!wake_up_state(t, mask))
698 kick_process(t);
699}
700
701/*
702 * Remove signals in mask from the pending set and queue.
703 * Returns 1 if any signals were found.
704 *
705 * All callers must be holding the siglock.
706 *
707 * This version takes a sigset mask and looks at all signals,
708 * not just those in the first mask word.
709 */
710static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
711{
712 struct sigqueue *q, *n;
713 sigset_t m;
714
715 sigandsets(&m, mask, &s->signal);
716 if (sigisemptyset(&m))
717 return 0;
718
719 sigandnsets(&s->signal, &s->signal, mask);
720 list_for_each_entry_safe(q, n, &s->list, list) {
721 if (sigismember(mask, q->info.si_signo)) {
722 list_del_init(&q->list);
723 __sigqueue_free(q);
724 }
725 }
726 return 1;
727}
728/*
729 * Remove signals in mask from the pending set and queue.
730 * Returns 1 if any signals were found.
731 *
732 * All callers must be holding the siglock.
733 */
734static int rm_from_queue(unsigned long mask, struct sigpending *s)
735{
736 struct sigqueue *q, *n;
737
738 if (!sigtestsetmask(&s->signal, mask))
739 return 0;
740
741 sigdelsetmask(&s->signal, mask);
742 list_for_each_entry_safe(q, n, &s->list, list) {
743 if (q->info.si_signo < SIGRTMIN &&
744 (mask & sigmask(q->info.si_signo))) {
745 list_del_init(&q->list);
746 __sigqueue_free(q);
747 }
748 }
749 return 1;
750}
751
752static inline int is_si_special(const struct siginfo *info)
753{
754 return info <= SEND_SIG_FORCED;
755}
756
757static inline bool si_fromuser(const struct siginfo *info)
758{
759 return info == SEND_SIG_NOINFO ||
760 (!is_si_special(info) && SI_FROMUSER(info));
761}
762
763/*
764 * called with RCU read lock from check_kill_permission()
765 */
766static int kill_ok_by_cred(struct task_struct *t)
767{
768 const struct cred *cred = current_cred();
769 const struct cred *tcred = __task_cred(t);
770
771 if (uid_eq(cred->euid, tcred->suid) ||
772 uid_eq(cred->euid, tcred->uid) ||
773 uid_eq(cred->uid, tcred->suid) ||
774 uid_eq(cred->uid, tcred->uid))
775 return 1;
776
777 if (ns_capable(tcred->user_ns, CAP_KILL))
778 return 1;
779
780 return 0;
781}
782
783/*
784 * Bad permissions for sending the signal
785 * - the caller must hold the RCU read lock
786 */
787static int check_kill_permission(int sig, struct siginfo *info,
788 struct task_struct *t)
789{
790 struct pid *sid;
791 int error;
792
793 if (!valid_signal(sig))
794 return -EINVAL;
795
796 if (!si_fromuser(info))
797 return 0;
798
799 error = audit_signal_info(sig, t); /* Let audit system see the signal */
800 if (error)
801 return error;
802
803 if (!same_thread_group(current, t) &&
804 !kill_ok_by_cred(t)) {
805 switch (sig) {
806 case SIGCONT:
807 sid = task_session(t);
808 /*
809 * We don't return the error if sid == NULL. The
810 * task was unhashed, the caller must notice this.
811 */
812 if (!sid || sid == task_session(current))
813 break;
814 default:
815 return -EPERM;
816 }
817 }
818
819 return security_task_kill(t, info, sig, 0);
820}
821
822/**
823 * ptrace_trap_notify - schedule trap to notify ptracer
824 * @t: tracee wanting to notify tracer
825 *
826 * This function schedules sticky ptrace trap which is cleared on the next
827 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
828 * ptracer.
829 *
830 * If @t is running, STOP trap will be taken. If trapped for STOP and
831 * ptracer is listening for events, tracee is woken up so that it can
832 * re-trap for the new event. If trapped otherwise, STOP trap will be
833 * eventually taken without returning to userland after the existing traps
834 * are finished by PTRACE_CONT.
835 *
836 * CONTEXT:
837 * Must be called with @task->sighand->siglock held.
838 */
839static void ptrace_trap_notify(struct task_struct *t)
840{
841 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
842 assert_spin_locked(&t->sighand->siglock);
843
844 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
845 signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
846}
847
848/*
849 * Handle magic process-wide effects of stop/continue signals. Unlike
850 * the signal actions, these happen immediately at signal-generation
851 * time regardless of blocking, ignoring, or handling. This does the
852 * actual continuing for SIGCONT, but not the actual stopping for stop
853 * signals. The process stop is done as a signal action for SIG_DFL.
854 *
855 * Returns true if the signal should be actually delivered, otherwise
856 * it should be dropped.
857 */
858static int prepare_signal(int sig, struct task_struct *p, bool force)
859{
860 struct signal_struct *signal = p->signal;
861 struct task_struct *t;
862
863 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
864 /*
865 * The process is in the middle of dying, nothing to do.
866 */
867 } else if (sig_kernel_stop(sig)) {
868 /*
869 * This is a stop signal. Remove SIGCONT from all queues.
870 */
871 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
872 t = p;
873 do {
874 rm_from_queue(sigmask(SIGCONT), &t->pending);
875 } while_each_thread(p, t);
876 } else if (sig == SIGCONT) {
877 unsigned int why;
878 /*
879 * Remove all stop signals from all queues, wake all threads.
880 */
881 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
882 t = p;
883 do {
884 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
885 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
886 if (likely(!(t->ptrace & PT_SEIZED)))
887 wake_up_state(t, __TASK_STOPPED);
888 else
889 ptrace_trap_notify(t);
890 } while_each_thread(p, t);
891
892 /*
893 * Notify the parent with CLD_CONTINUED if we were stopped.
894 *
895 * If we were in the middle of a group stop, we pretend it
896 * was already finished, and then continued. Since SIGCHLD
897 * doesn't queue we report only CLD_STOPPED, as if the next
898 * CLD_CONTINUED was dropped.
899 */
900 why = 0;
901 if (signal->flags & SIGNAL_STOP_STOPPED)
902 why |= SIGNAL_CLD_CONTINUED;
903 else if (signal->group_stop_count)
904 why |= SIGNAL_CLD_STOPPED;
905
906 if (why) {
907 /*
908 * The first thread which returns from do_signal_stop()
909 * will take ->siglock, notice SIGNAL_CLD_MASK, and
910 * notify its parent. See get_signal_to_deliver().
911 */
912 signal->flags = why | SIGNAL_STOP_CONTINUED;
913 signal->group_stop_count = 0;
914 signal->group_exit_code = 0;
915 }
916 }
917
918 return !sig_ignored(p, sig, force);
919}
920
921/*
922 * Test if P wants to take SIG. After we've checked all threads with this,
923 * it's equivalent to finding no threads not blocking SIG. Any threads not
924 * blocking SIG were ruled out because they are not running and already
925 * have pending signals. Such threads will dequeue from the shared queue
926 * as soon as they're available, so putting the signal on the shared queue
927 * will be equivalent to sending it to one such thread.
928 */
929static inline int wants_signal(int sig, struct task_struct *p)
930{
931 if (sigismember(&p->blocked, sig))
932 return 0;
933 if (p->flags & PF_EXITING)
934 return 0;
935 if (sig == SIGKILL)
936 return 1;
937 if (task_is_stopped_or_traced(p))
938 return 0;
939 return task_curr(p) || !signal_pending(p);
940}
941
942static void complete_signal(int sig, struct task_struct *p, int group)
943{
944 struct signal_struct *signal = p->signal;
945 struct task_struct *t;
946
947 /*
948 * Now find a thread we can wake up to take the signal off the queue.
949 *
950 * If the main thread wants the signal, it gets first crack.
951 * Probably the least surprising to the average bear.
952 */
953 if (wants_signal(sig, p))
954 t = p;
955 else if (!group || thread_group_empty(p))
956 /*
957 * There is just one thread and it does not need to be woken.
958 * It will dequeue unblocked signals before it runs again.
959 */
960 return;
961 else {
962 /*
963 * Otherwise try to find a suitable thread.
964 */
965 t = signal->curr_target;
966 while (!wants_signal(sig, t)) {
967 t = next_thread(t);
968 if (t == signal->curr_target)
969 /*
970 * No thread needs to be woken.
971 * Any eligible threads will see
972 * the signal in the queue soon.
973 */
974 return;
975 }
976 signal->curr_target = t;
977 }
978
979 /*
980 * Found a killable thread. If the signal will be fatal,
981 * then start taking the whole group down immediately.
982 */
983 if (sig_fatal(p, sig) &&
984 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
985 !sigismember(&t->real_blocked, sig) &&
986 (sig == SIGKILL || !t->ptrace)) {
987 /*
988 * This signal will be fatal to the whole group.
989 */
990 if (!sig_kernel_coredump(sig)) {
991 /*
992 * Start a group exit and wake everybody up.
993 * This way we don't have other threads
994 * running and doing things after a slower
995 * thread has the fatal signal pending.
996 */
997 signal->flags = SIGNAL_GROUP_EXIT;
998 signal->group_exit_code = sig;
999 signal->group_stop_count = 0;
1000 t = p;
1001 do {
1002 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1003 sigaddset(&t->pending.signal, SIGKILL);
1004 signal_wake_up(t, 1);
1005 } while_each_thread(p, t);
1006 return;
1007 }
1008 }
1009
1010 /*
1011 * The signal is already in the shared-pending queue.
1012 * Tell the chosen thread to wake up and dequeue it.
1013 */
1014 signal_wake_up(t, sig == SIGKILL);
1015 return;
1016}
1017
1018static inline int legacy_queue(struct sigpending *signals, int sig)
1019{
1020 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1021}
1022
1023#ifdef CONFIG_USER_NS
1024static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1025{
1026 if (current_user_ns() == task_cred_xxx(t, user_ns))
1027 return;
1028
1029 if (SI_FROMKERNEL(info))
1030 return;
1031
1032 rcu_read_lock();
1033 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1034 make_kuid(current_user_ns(), info->si_uid));
1035 rcu_read_unlock();
1036}
1037#else
1038static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1039{
1040 return;
1041}
1042#endif
1043
1044static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1045 int group, int from_ancestor_ns)
1046{
1047 struct sigpending *pending;
1048 struct sigqueue *q;
1049 int override_rlimit;
1050 int ret = 0, result;
1051
1052 assert_spin_locked(&t->sighand->siglock);
1053
1054 result = TRACE_SIGNAL_IGNORED;
1055 if (!prepare_signal(sig, t,
1056 from_ancestor_ns || (info == SEND_SIG_FORCED)))
1057 goto ret;
1058
1059 pending = group ? &t->signal->shared_pending : &t->pending;
1060 /*
1061 * Short-circuit ignored signals and support queuing
1062 * exactly one non-rt signal, so that we can get more
1063 * detailed information about the cause of the signal.
1064 */
1065 result = TRACE_SIGNAL_ALREADY_PENDING;
1066 if (legacy_queue(pending, sig))
1067 goto ret;
1068
1069 result = TRACE_SIGNAL_DELIVERED;
1070 /*
1071 * fast-pathed signals for kernel-internal things like SIGSTOP
1072 * or SIGKILL.
1073 */
1074 if (info == SEND_SIG_FORCED)
1075 goto out_set;
1076
1077 /*
1078 * Real-time signals must be queued if sent by sigqueue, or
1079 * some other real-time mechanism. It is implementation
1080 * defined whether kill() does so. We attempt to do so, on
1081 * the principle of least surprise, but since kill is not
1082 * allowed to fail with EAGAIN when low on memory we just
1083 * make sure at least one signal gets delivered and don't
1084 * pass on the info struct.
1085 */
1086 if (sig < SIGRTMIN)
1087 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1088 else
1089 override_rlimit = 0;
1090
1091 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1092 override_rlimit);
1093 if (q) {
1094 list_add_tail(&q->list, &pending->list);
1095 switch ((unsigned long) info) {
1096 case (unsigned long) SEND_SIG_NOINFO:
1097 q->info.si_signo = sig;
1098 q->info.si_errno = 0;
1099 q->info.si_code = SI_USER;
1100 q->info.si_pid = task_tgid_nr_ns(current,
1101 task_active_pid_ns(t));
1102 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1103 break;
1104 case (unsigned long) SEND_SIG_PRIV:
1105 q->info.si_signo = sig;
1106 q->info.si_errno = 0;
1107 q->info.si_code = SI_KERNEL;
1108 q->info.si_pid = 0;
1109 q->info.si_uid = 0;
1110 break;
1111 default:
1112 copy_siginfo(&q->info, info);
1113 if (from_ancestor_ns)
1114 q->info.si_pid = 0;
1115 break;
1116 }
1117
1118 userns_fixup_signal_uid(&q->info, t);
1119
1120 } else if (!is_si_special(info)) {
1121 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1122 /*
1123 * Queue overflow, abort. We may abort if the
1124 * signal was rt and sent by user using something
1125 * other than kill().
1126 */
1127 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1128 ret = -EAGAIN;
1129 goto ret;
1130 } else {
1131 /*
1132 * This is a silent loss of information. We still
1133 * send the signal, but the *info bits are lost.
1134 */
1135 result = TRACE_SIGNAL_LOSE_INFO;
1136 }
1137 }
1138
1139out_set:
1140 signalfd_notify(t, sig);
1141 sigaddset(&pending->signal, sig);
1142 complete_signal(sig, t, group);
1143ret:
1144 trace_signal_generate(sig, info, t, group, result);
1145 return ret;
1146}
1147
1148static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1149 int group)
1150{
1151 int from_ancestor_ns = 0;
1152
1153#ifdef CONFIG_PID_NS
1154 from_ancestor_ns = si_fromuser(info) &&
1155 !task_pid_nr_ns(current, task_active_pid_ns(t));
1156#endif
1157
1158 return __send_signal(sig, info, t, group, from_ancestor_ns);
1159}
1160
1161static void print_fatal_signal(struct pt_regs *regs, int signr)
1162{
1163 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1164 current->comm, task_pid_nr(current), signr);
1165
1166#if defined(__i386__) && !defined(__arch_um__)
1167 printk("code at %08lx: ", regs->ip);
1168 {
1169 int i;
1170 for (i = 0; i < 16; i++) {
1171 unsigned char insn;
1172
1173 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1174 break;
1175 printk("%02x ", insn);
1176 }
1177 }
1178#endif
1179 printk("\n");
1180 preempt_disable();
1181 show_regs(regs);
1182 preempt_enable();
1183}
1184
1185static int __init setup_print_fatal_signals(char *str)
1186{
1187 get_option (&str, &print_fatal_signals);
1188
1189 return 1;
1190}
1191
1192__setup("print-fatal-signals=", setup_print_fatal_signals);
1193
1194int
1195__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1196{
1197 return send_signal(sig, info, p, 1);
1198}
1199
1200static int
1201specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1202{
1203 return send_signal(sig, info, t, 0);
1204}
1205
1206int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1207 bool group)
1208{
1209 unsigned long flags;
1210 int ret = -ESRCH;
1211
1212 if (lock_task_sighand(p, &flags)) {
1213 ret = send_signal(sig, info, p, group);
1214 unlock_task_sighand(p, &flags);
1215 }
1216
1217 return ret;
1218}
1219
1220/*
1221 * Force a signal that the process can't ignore: if necessary
1222 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1223 *
1224 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1225 * since we do not want to have a signal handler that was blocked
1226 * be invoked when user space had explicitly blocked it.
1227 *
1228 * We don't want to have recursive SIGSEGV's etc, for example,
1229 * that is why we also clear SIGNAL_UNKILLABLE.
1230 */
1231int
1232force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1233{
1234 unsigned long int flags;
1235 int ret, blocked, ignored;
1236 struct k_sigaction *action;
1237
1238 spin_lock_irqsave(&t->sighand->siglock, flags);
1239 action = &t->sighand->action[sig-1];
1240 ignored = action->sa.sa_handler == SIG_IGN;
1241 blocked = sigismember(&t->blocked, sig);
1242 if (blocked || ignored) {
1243 action->sa.sa_handler = SIG_DFL;
1244 if (blocked) {
1245 sigdelset(&t->blocked, sig);
1246 recalc_sigpending_and_wake(t);
1247 }
1248 }
1249 if (action->sa.sa_handler == SIG_DFL)
1250 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1251 ret = specific_send_sig_info(sig, info, t);
1252 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1253
1254 return ret;
1255}
1256
1257/*
1258 * Nuke all other threads in the group.
1259 */
1260int zap_other_threads(struct task_struct *p)
1261{
1262 struct task_struct *t = p;
1263 int count = 0;
1264
1265 p->signal->group_stop_count = 0;
1266
1267 while_each_thread(p, t) {
1268 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1269 count++;
1270
1271 /* Don't bother with already dead threads */
1272 if (t->exit_state)
1273 continue;
1274 sigaddset(&t->pending.signal, SIGKILL);
1275 signal_wake_up(t, 1);
1276 }
1277
1278 return count;
1279}
1280
1281struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1282 unsigned long *flags)
1283{
1284 struct sighand_struct *sighand;
1285
1286 for (;;) {
1287 local_irq_save(*flags);
1288 rcu_read_lock();
1289 sighand = rcu_dereference(tsk->sighand);
1290 if (unlikely(sighand == NULL)) {
1291 rcu_read_unlock();
1292 local_irq_restore(*flags);
1293 break;
1294 }
1295
1296 spin_lock(&sighand->siglock);
1297 if (likely(sighand == tsk->sighand)) {
1298 rcu_read_unlock();
1299 break;
1300 }
1301 spin_unlock(&sighand->siglock);
1302 rcu_read_unlock();
1303 local_irq_restore(*flags);
1304 }
1305
1306 return sighand;
1307}
1308
1309/*
1310 * send signal info to all the members of a group
1311 */
1312int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1313{
1314 int ret;
1315
1316 rcu_read_lock();
1317 ret = check_kill_permission(sig, info, p);
1318 rcu_read_unlock();
1319
1320 if (!ret && sig)
1321 ret = do_send_sig_info(sig, info, p, true);
1322
1323 return ret;
1324}
1325
1326/*
1327 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1328 * control characters do (^C, ^Z etc)
1329 * - the caller must hold at least a readlock on tasklist_lock
1330 */
1331int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1332{
1333 struct task_struct *p = NULL;
1334 int retval, success;
1335
1336 success = 0;
1337 retval = -ESRCH;
1338 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1339 int err = group_send_sig_info(sig, info, p);
1340 success |= !err;
1341 retval = err;
1342 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1343 return success ? 0 : retval;
1344}
1345
1346int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1347{
1348 int error = -ESRCH;
1349 struct task_struct *p;
1350
1351 rcu_read_lock();
1352retry:
1353 p = pid_task(pid, PIDTYPE_PID);
1354 if (p) {
1355 error = group_send_sig_info(sig, info, p);
1356 if (unlikely(error == -ESRCH))
1357 /*
1358 * The task was unhashed in between, try again.
1359 * If it is dead, pid_task() will return NULL,
1360 * if we race with de_thread() it will find the
1361 * new leader.
1362 */
1363 goto retry;
1364 }
1365 rcu_read_unlock();
1366
1367 return error;
1368}
1369
1370int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1371{
1372 int error;
1373 rcu_read_lock();
1374 error = kill_pid_info(sig, info, find_vpid(pid));
1375 rcu_read_unlock();
1376 return error;
1377}
1378
1379static int kill_as_cred_perm(const struct cred *cred,
1380 struct task_struct *target)
1381{
1382 const struct cred *pcred = __task_cred(target);
1383 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1384 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1385 return 0;
1386 return 1;
1387}
1388
1389/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1390int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1391 const struct cred *cred, u32 secid)
1392{
1393 int ret = -EINVAL;
1394 struct task_struct *p;
1395 unsigned long flags;
1396
1397 if (!valid_signal(sig))
1398 return ret;
1399
1400 rcu_read_lock();
1401 p = pid_task(pid, PIDTYPE_PID);
1402 if (!p) {
1403 ret = -ESRCH;
1404 goto out_unlock;
1405 }
1406 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1407 ret = -EPERM;
1408 goto out_unlock;
1409 }
1410 ret = security_task_kill(p, info, sig, secid);
1411 if (ret)
1412 goto out_unlock;
1413
1414 if (sig) {
1415 if (lock_task_sighand(p, &flags)) {
1416 ret = __send_signal(sig, info, p, 1, 0);
1417 unlock_task_sighand(p, &flags);
1418 } else
1419 ret = -ESRCH;
1420 }
1421out_unlock:
1422 rcu_read_unlock();
1423 return ret;
1424}
1425EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1426
1427/*
1428 * kill_something_info() interprets pid in interesting ways just like kill(2).
1429 *
1430 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1431 * is probably wrong. Should make it like BSD or SYSV.
1432 */
1433
1434static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1435{
1436 int ret;
1437
1438 if (pid > 0) {
1439 rcu_read_lock();
1440 ret = kill_pid_info(sig, info, find_vpid(pid));
1441 rcu_read_unlock();
1442 return ret;
1443 }
1444
1445 read_lock(&tasklist_lock);
1446 if (pid != -1) {
1447 ret = __kill_pgrp_info(sig, info,
1448 pid ? find_vpid(-pid) : task_pgrp(current));
1449 } else {
1450 int retval = 0, count = 0;
1451 struct task_struct * p;
1452
1453 for_each_process(p) {
1454 if (task_pid_vnr(p) > 1 &&
1455 !same_thread_group(p, current)) {
1456 int err = group_send_sig_info(sig, info, p);
1457 ++count;
1458 if (err != -EPERM)
1459 retval = err;
1460 }
1461 }
1462 ret = count ? retval : -ESRCH;
1463 }
1464 read_unlock(&tasklist_lock);
1465
1466 return ret;
1467}
1468
1469/*
1470 * These are for backward compatibility with the rest of the kernel source.
1471 */
1472
1473int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1474{
1475 /*
1476 * Make sure legacy kernel users don't send in bad values
1477 * (normal paths check this in check_kill_permission).
1478 */
1479 if (!valid_signal(sig))
1480 return -EINVAL;
1481
1482 return do_send_sig_info(sig, info, p, false);
1483}
1484
1485#define __si_special(priv) \
1486 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1487
1488int
1489send_sig(int sig, struct task_struct *p, int priv)
1490{
1491 return send_sig_info(sig, __si_special(priv), p);
1492}
1493
1494void
1495force_sig(int sig, struct task_struct *p)
1496{
1497 force_sig_info(sig, SEND_SIG_PRIV, p);
1498}
1499
1500/*
1501 * When things go south during signal handling, we
1502 * will force a SIGSEGV. And if the signal that caused
1503 * the problem was already a SIGSEGV, we'll want to
1504 * make sure we don't even try to deliver the signal..
1505 */
1506int
1507force_sigsegv(int sig, struct task_struct *p)
1508{
1509 if (sig == SIGSEGV) {
1510 unsigned long flags;
1511 spin_lock_irqsave(&p->sighand->siglock, flags);
1512 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1513 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1514 }
1515 force_sig(SIGSEGV, p);
1516 return 0;
1517}
1518
1519int kill_pgrp(struct pid *pid, int sig, int priv)
1520{
1521 int ret;
1522
1523 read_lock(&tasklist_lock);
1524 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1525 read_unlock(&tasklist_lock);
1526
1527 return ret;
1528}
1529EXPORT_SYMBOL(kill_pgrp);
1530
1531int kill_pid(struct pid *pid, int sig, int priv)
1532{
1533 return kill_pid_info(sig, __si_special(priv), pid);
1534}
1535EXPORT_SYMBOL(kill_pid);
1536
1537/*
1538 * These functions support sending signals using preallocated sigqueue
1539 * structures. This is needed "because realtime applications cannot
1540 * afford to lose notifications of asynchronous events, like timer
1541 * expirations or I/O completions". In the case of POSIX Timers
1542 * we allocate the sigqueue structure from the timer_create. If this
1543 * allocation fails we are able to report the failure to the application
1544 * with an EAGAIN error.
1545 */
1546struct sigqueue *sigqueue_alloc(void)
1547{
1548 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1549
1550 if (q)
1551 q->flags |= SIGQUEUE_PREALLOC;
1552
1553 return q;
1554}
1555
1556void sigqueue_free(struct sigqueue *q)
1557{
1558 unsigned long flags;
1559 spinlock_t *lock = ¤t->sighand->siglock;
1560
1561 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1562 /*
1563 * We must hold ->siglock while testing q->list
1564 * to serialize with collect_signal() or with
1565 * __exit_signal()->flush_sigqueue().
1566 */
1567 spin_lock_irqsave(lock, flags);
1568 q->flags &= ~SIGQUEUE_PREALLOC;
1569 /*
1570 * If it is queued it will be freed when dequeued,
1571 * like the "regular" sigqueue.
1572 */
1573 if (!list_empty(&q->list))
1574 q = NULL;
1575 spin_unlock_irqrestore(lock, flags);
1576
1577 if (q)
1578 __sigqueue_free(q);
1579}
1580
1581int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1582{
1583 int sig = q->info.si_signo;
1584 struct sigpending *pending;
1585 unsigned long flags;
1586 int ret, result;
1587
1588 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1589
1590 ret = -1;
1591 if (!likely(lock_task_sighand(t, &flags)))
1592 goto ret;
1593
1594 ret = 1; /* the signal is ignored */
1595 result = TRACE_SIGNAL_IGNORED;
1596 if (!prepare_signal(sig, t, false))
1597 goto out;
1598
1599 ret = 0;
1600 if (unlikely(!list_empty(&q->list))) {
1601 /*
1602 * If an SI_TIMER entry is already queue just increment
1603 * the overrun count.
1604 */
1605 BUG_ON(q->info.si_code != SI_TIMER);
1606 q->info.si_overrun++;
1607 result = TRACE_SIGNAL_ALREADY_PENDING;
1608 goto out;
1609 }
1610 q->info.si_overrun = 0;
1611
1612 signalfd_notify(t, sig);
1613 pending = group ? &t->signal->shared_pending : &t->pending;
1614 list_add_tail(&q->list, &pending->list);
1615 sigaddset(&pending->signal, sig);
1616 complete_signal(sig, t, group);
1617 result = TRACE_SIGNAL_DELIVERED;
1618out:
1619 trace_signal_generate(sig, &q->info, t, group, result);
1620 unlock_task_sighand(t, &flags);
1621ret:
1622 return ret;
1623}
1624
1625/*
1626 * Let a parent know about the death of a child.
1627 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1628 *
1629 * Returns true if our parent ignored us and so we've switched to
1630 * self-reaping.
1631 */
1632bool do_notify_parent(struct task_struct *tsk, int sig)
1633{
1634 struct siginfo info;
1635 unsigned long flags;
1636 struct sighand_struct *psig;
1637 bool autoreap = false;
1638
1639 BUG_ON(sig == -1);
1640
1641 /* do_notify_parent_cldstop should have been called instead. */
1642 BUG_ON(task_is_stopped_or_traced(tsk));
1643
1644 BUG_ON(!tsk->ptrace &&
1645 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1646
1647 if (sig != SIGCHLD) {
1648 /*
1649 * This is only possible if parent == real_parent.
1650 * Check if it has changed security domain.
1651 */
1652 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1653 sig = SIGCHLD;
1654 }
1655
1656 info.si_signo = sig;
1657 info.si_errno = 0;
1658 /*
1659 * We are under tasklist_lock here so our parent is tied to
1660 * us and cannot change.
1661 *
1662 * task_active_pid_ns will always return the same pid namespace
1663 * until a task passes through release_task.
1664 *
1665 * write_lock() currently calls preempt_disable() which is the
1666 * same as rcu_read_lock(), but according to Oleg, this is not
1667 * correct to rely on this
1668 */
1669 rcu_read_lock();
1670 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1671 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1672 task_uid(tsk));
1673 rcu_read_unlock();
1674
1675 info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
1676 info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
1677
1678 info.si_status = tsk->exit_code & 0x7f;
1679 if (tsk->exit_code & 0x80)
1680 info.si_code = CLD_DUMPED;
1681 else if (tsk->exit_code & 0x7f)
1682 info.si_code = CLD_KILLED;
1683 else {
1684 info.si_code = CLD_EXITED;
1685 info.si_status = tsk->exit_code >> 8;
1686 }
1687
1688 psig = tsk->parent->sighand;
1689 spin_lock_irqsave(&psig->siglock, flags);
1690 if (!tsk->ptrace && sig == SIGCHLD &&
1691 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1692 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1693 /*
1694 * We are exiting and our parent doesn't care. POSIX.1
1695 * defines special semantics for setting SIGCHLD to SIG_IGN
1696 * or setting the SA_NOCLDWAIT flag: we should be reaped
1697 * automatically and not left for our parent's wait4 call.
1698 * Rather than having the parent do it as a magic kind of
1699 * signal handler, we just set this to tell do_exit that we
1700 * can be cleaned up without becoming a zombie. Note that
1701 * we still call __wake_up_parent in this case, because a
1702 * blocked sys_wait4 might now return -ECHILD.
1703 *
1704 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1705 * is implementation-defined: we do (if you don't want
1706 * it, just use SIG_IGN instead).
1707 */
1708 autoreap = true;
1709 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1710 sig = 0;
1711 }
1712 if (valid_signal(sig) && sig)
1713 __group_send_sig_info(sig, &info, tsk->parent);
1714 __wake_up_parent(tsk, tsk->parent);
1715 spin_unlock_irqrestore(&psig->siglock, flags);
1716
1717 return autoreap;
1718}
1719
1720/**
1721 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1722 * @tsk: task reporting the state change
1723 * @for_ptracer: the notification is for ptracer
1724 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1725 *
1726 * Notify @tsk's parent that the stopped/continued state has changed. If
1727 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1728 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1729 *
1730 * CONTEXT:
1731 * Must be called with tasklist_lock at least read locked.
1732 */
1733static void do_notify_parent_cldstop(struct task_struct *tsk,
1734 bool for_ptracer, int why)
1735{
1736 struct siginfo info;
1737 unsigned long flags;
1738 struct task_struct *parent;
1739 struct sighand_struct *sighand;
1740
1741 if (for_ptracer) {
1742 parent = tsk->parent;
1743 } else {
1744 tsk = tsk->group_leader;
1745 parent = tsk->real_parent;
1746 }
1747
1748 info.si_signo = SIGCHLD;
1749 info.si_errno = 0;
1750 /*
1751 * see comment in do_notify_parent() about the following 4 lines
1752 */
1753 rcu_read_lock();
1754 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1755 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1756 rcu_read_unlock();
1757
1758 info.si_utime = cputime_to_clock_t(tsk->utime);
1759 info.si_stime = cputime_to_clock_t(tsk->stime);
1760
1761 info.si_code = why;
1762 switch (why) {
1763 case CLD_CONTINUED:
1764 info.si_status = SIGCONT;
1765 break;
1766 case CLD_STOPPED:
1767 info.si_status = tsk->signal->group_exit_code & 0x7f;
1768 break;
1769 case CLD_TRAPPED:
1770 info.si_status = tsk->exit_code & 0x7f;
1771 break;
1772 default:
1773 BUG();
1774 }
1775
1776 sighand = parent->sighand;
1777 spin_lock_irqsave(&sighand->siglock, flags);
1778 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1779 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1780 __group_send_sig_info(SIGCHLD, &info, parent);
1781 /*
1782 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1783 */
1784 __wake_up_parent(tsk, parent);
1785 spin_unlock_irqrestore(&sighand->siglock, flags);
1786}
1787
1788static inline int may_ptrace_stop(void)
1789{
1790 if (!likely(current->ptrace))
1791 return 0;
1792 /*
1793 * Are we in the middle of do_coredump?
1794 * If so and our tracer is also part of the coredump stopping
1795 * is a deadlock situation, and pointless because our tracer
1796 * is dead so don't allow us to stop.
1797 * If SIGKILL was already sent before the caller unlocked
1798 * ->siglock we must see ->core_state != NULL. Otherwise it
1799 * is safe to enter schedule().
1800 */
1801 if (unlikely(current->mm->core_state) &&
1802 unlikely(current->mm == current->parent->mm))
1803 return 0;
1804
1805 return 1;
1806}
1807
1808/*
1809 * Return non-zero if there is a SIGKILL that should be waking us up.
1810 * Called with the siglock held.
1811 */
1812static int sigkill_pending(struct task_struct *tsk)
1813{
1814 return sigismember(&tsk->pending.signal, SIGKILL) ||
1815 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1816}
1817
1818/*
1819 * This must be called with current->sighand->siglock held.
1820 *
1821 * This should be the path for all ptrace stops.
1822 * We always set current->last_siginfo while stopped here.
1823 * That makes it a way to test a stopped process for
1824 * being ptrace-stopped vs being job-control-stopped.
1825 *
1826 * If we actually decide not to stop at all because the tracer
1827 * is gone, we keep current->exit_code unless clear_code.
1828 */
1829static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1830 __releases(¤t->sighand->siglock)
1831 __acquires(¤t->sighand->siglock)
1832{
1833 bool gstop_done = false;
1834
1835 if (arch_ptrace_stop_needed(exit_code, info)) {
1836 /*
1837 * The arch code has something special to do before a
1838 * ptrace stop. This is allowed to block, e.g. for faults
1839 * on user stack pages. We can't keep the siglock while
1840 * calling arch_ptrace_stop, so we must release it now.
1841 * To preserve proper semantics, we must do this before
1842 * any signal bookkeeping like checking group_stop_count.
1843 * Meanwhile, a SIGKILL could come in before we retake the
1844 * siglock. That must prevent us from sleeping in TASK_TRACED.
1845 * So after regaining the lock, we must check for SIGKILL.
1846 */
1847 spin_unlock_irq(¤t->sighand->siglock);
1848 arch_ptrace_stop(exit_code, info);
1849 spin_lock_irq(¤t->sighand->siglock);
1850 if (sigkill_pending(current))
1851 return;
1852 }
1853
1854 /*
1855 * We're committing to trapping. TRACED should be visible before
1856 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1857 * Also, transition to TRACED and updates to ->jobctl should be
1858 * atomic with respect to siglock and should be done after the arch
1859 * hook as siglock is released and regrabbed across it.
1860 */
1861 set_current_state(TASK_TRACED);
1862
1863 current->last_siginfo = info;
1864 current->exit_code = exit_code;
1865
1866 /*
1867 * If @why is CLD_STOPPED, we're trapping to participate in a group
1868 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1869 * across siglock relocks since INTERRUPT was scheduled, PENDING
1870 * could be clear now. We act as if SIGCONT is received after
1871 * TASK_TRACED is entered - ignore it.
1872 */
1873 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1874 gstop_done = task_participate_group_stop(current);
1875
1876 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1877 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1878 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1879 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1880
1881 /* entering a trap, clear TRAPPING */
1882 task_clear_jobctl_trapping(current);
1883
1884 spin_unlock_irq(¤t->sighand->siglock);
1885 read_lock(&tasklist_lock);
1886 if (may_ptrace_stop()) {
1887 /*
1888 * Notify parents of the stop.
1889 *
1890 * While ptraced, there are two parents - the ptracer and
1891 * the real_parent of the group_leader. The ptracer should
1892 * know about every stop while the real parent is only
1893 * interested in the completion of group stop. The states
1894 * for the two don't interact with each other. Notify
1895 * separately unless they're gonna be duplicates.
1896 */
1897 do_notify_parent_cldstop(current, true, why);
1898 if (gstop_done && ptrace_reparented(current))
1899 do_notify_parent_cldstop(current, false, why);
1900
1901 /*
1902 * Don't want to allow preemption here, because
1903 * sys_ptrace() needs this task to be inactive.
1904 *
1905 * XXX: implement read_unlock_no_resched().
1906 */
1907 preempt_disable();
1908 read_unlock(&tasklist_lock);
1909 preempt_enable_no_resched();
1910 schedule();
1911 } else {
1912 /*
1913 * By the time we got the lock, our tracer went away.
1914 * Don't drop the lock yet, another tracer may come.
1915 *
1916 * If @gstop_done, the ptracer went away between group stop
1917 * completion and here. During detach, it would have set
1918 * JOBCTL_STOP_PENDING on us and we'll re-enter
1919 * TASK_STOPPED in do_signal_stop() on return, so notifying
1920 * the real parent of the group stop completion is enough.
1921 */
1922 if (gstop_done)
1923 do_notify_parent_cldstop(current, false, why);
1924
1925 __set_current_state(TASK_RUNNING);
1926 if (clear_code)
1927 current->exit_code = 0;
1928 read_unlock(&tasklist_lock);
1929 }
1930
1931 /*
1932 * While in TASK_TRACED, we were considered "frozen enough".
1933 * Now that we woke up, it's crucial if we're supposed to be
1934 * frozen that we freeze now before running anything substantial.
1935 */
1936 try_to_freeze();
1937
1938 /*
1939 * We are back. Now reacquire the siglock before touching
1940 * last_siginfo, so that we are sure to have synchronized with
1941 * any signal-sending on another CPU that wants to examine it.
1942 */
1943 spin_lock_irq(¤t->sighand->siglock);
1944 current->last_siginfo = NULL;
1945
1946 /* LISTENING can be set only during STOP traps, clear it */
1947 current->jobctl &= ~JOBCTL_LISTENING;
1948
1949 /*
1950 * Queued signals ignored us while we were stopped for tracing.
1951 * So check for any that we should take before resuming user mode.
1952 * This sets TIF_SIGPENDING, but never clears it.
1953 */
1954 recalc_sigpending_tsk(current);
1955}
1956
1957static void ptrace_do_notify(int signr, int exit_code, int why)
1958{
1959 siginfo_t info;
1960
1961 memset(&info, 0, sizeof info);
1962 info.si_signo = signr;
1963 info.si_code = exit_code;
1964 info.si_pid = task_pid_vnr(current);
1965 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1966
1967 /* Let the debugger run. */
1968 ptrace_stop(exit_code, why, 1, &info);
1969}
1970
1971void ptrace_notify(int exit_code)
1972{
1973 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1974
1975 spin_lock_irq(¤t->sighand->siglock);
1976 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1977 spin_unlock_irq(¤t->sighand->siglock);
1978}
1979
1980/**
1981 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1982 * @signr: signr causing group stop if initiating
1983 *
1984 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1985 * and participate in it. If already set, participate in the existing
1986 * group stop. If participated in a group stop (and thus slept), %true is
1987 * returned with siglock released.
1988 *
1989 * If ptraced, this function doesn't handle stop itself. Instead,
1990 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1991 * untouched. The caller must ensure that INTERRUPT trap handling takes
1992 * places afterwards.
1993 *
1994 * CONTEXT:
1995 * Must be called with @current->sighand->siglock held, which is released
1996 * on %true return.
1997 *
1998 * RETURNS:
1999 * %false if group stop is already cancelled or ptrace trap is scheduled.
2000 * %true if participated in group stop.
2001 */
2002static bool do_signal_stop(int signr)
2003 __releases(¤t->sighand->siglock)
2004{
2005 struct signal_struct *sig = current->signal;
2006
2007 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2008 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2009 struct task_struct *t;
2010
2011 /* signr will be recorded in task->jobctl for retries */
2012 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2013
2014 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2015 unlikely(signal_group_exit(sig)))
2016 return false;
2017 /*
2018 * There is no group stop already in progress. We must
2019 * initiate one now.
2020 *
2021 * While ptraced, a task may be resumed while group stop is
2022 * still in effect and then receive a stop signal and
2023 * initiate another group stop. This deviates from the
2024 * usual behavior as two consecutive stop signals can't
2025 * cause two group stops when !ptraced. That is why we
2026 * also check !task_is_stopped(t) below.
2027 *
2028 * The condition can be distinguished by testing whether
2029 * SIGNAL_STOP_STOPPED is already set. Don't generate
2030 * group_exit_code in such case.
2031 *
2032 * This is not necessary for SIGNAL_STOP_CONTINUED because
2033 * an intervening stop signal is required to cause two
2034 * continued events regardless of ptrace.
2035 */
2036 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2037 sig->group_exit_code = signr;
2038
2039 sig->group_stop_count = 0;
2040
2041 if (task_set_jobctl_pending(current, signr | gstop))
2042 sig->group_stop_count++;
2043
2044 for (t = next_thread(current); t != current;
2045 t = next_thread(t)) {
2046 /*
2047 * Setting state to TASK_STOPPED for a group
2048 * stop is always done with the siglock held,
2049 * so this check has no races.
2050 */
2051 if (!task_is_stopped(t) &&
2052 task_set_jobctl_pending(t, signr | gstop)) {
2053 sig->group_stop_count++;
2054 if (likely(!(t->ptrace & PT_SEIZED)))
2055 signal_wake_up(t, 0);
2056 else
2057 ptrace_trap_notify(t);
2058 }
2059 }
2060 }
2061
2062 if (likely(!current->ptrace)) {
2063 int notify = 0;
2064
2065 /*
2066 * If there are no other threads in the group, or if there
2067 * is a group stop in progress and we are the last to stop,
2068 * report to the parent.
2069 */
2070 if (task_participate_group_stop(current))
2071 notify = CLD_STOPPED;
2072
2073 __set_current_state(TASK_STOPPED);
2074 spin_unlock_irq(¤t->sighand->siglock);
2075
2076 /*
2077 * Notify the parent of the group stop completion. Because
2078 * we're not holding either the siglock or tasklist_lock
2079 * here, ptracer may attach inbetween; however, this is for
2080 * group stop and should always be delivered to the real
2081 * parent of the group leader. The new ptracer will get
2082 * its notification when this task transitions into
2083 * TASK_TRACED.
2084 */
2085 if (notify) {
2086 read_lock(&tasklist_lock);
2087 do_notify_parent_cldstop(current, false, notify);
2088 read_unlock(&tasklist_lock);
2089 }
2090
2091 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2092 schedule();
2093 return true;
2094 } else {
2095 /*
2096 * While ptraced, group stop is handled by STOP trap.
2097 * Schedule it and let the caller deal with it.
2098 */
2099 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2100 return false;
2101 }
2102}
2103
2104/**
2105 * do_jobctl_trap - take care of ptrace jobctl traps
2106 *
2107 * When PT_SEIZED, it's used for both group stop and explicit
2108 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2109 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2110 * the stop signal; otherwise, %SIGTRAP.
2111 *
2112 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2113 * number as exit_code and no siginfo.
2114 *
2115 * CONTEXT:
2116 * Must be called with @current->sighand->siglock held, which may be
2117 * released and re-acquired before returning with intervening sleep.
2118 */
2119static void do_jobctl_trap(void)
2120{
2121 struct signal_struct *signal = current->signal;
2122 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2123
2124 if (current->ptrace & PT_SEIZED) {
2125 if (!signal->group_stop_count &&
2126 !(signal->flags & SIGNAL_STOP_STOPPED))
2127 signr = SIGTRAP;
2128 WARN_ON_ONCE(!signr);
2129 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2130 CLD_STOPPED);
2131 } else {
2132 WARN_ON_ONCE(!signr);
2133 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2134 current->exit_code = 0;
2135 }
2136}
2137
2138static int ptrace_signal(int signr, siginfo_t *info,
2139 struct pt_regs *regs, void *cookie)
2140{
2141 ptrace_signal_deliver(regs, cookie);
2142 /*
2143 * We do not check sig_kernel_stop(signr) but set this marker
2144 * unconditionally because we do not know whether debugger will
2145 * change signr. This flag has no meaning unless we are going
2146 * to stop after return from ptrace_stop(). In this case it will
2147 * be checked in do_signal_stop(), we should only stop if it was
2148 * not cleared by SIGCONT while we were sleeping. See also the
2149 * comment in dequeue_signal().
2150 */
2151 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2152 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2153
2154 /* We're back. Did the debugger cancel the sig? */
2155 signr = current->exit_code;
2156 if (signr == 0)
2157 return signr;
2158
2159 current->exit_code = 0;
2160
2161 /*
2162 * Update the siginfo structure if the signal has
2163 * changed. If the debugger wanted something
2164 * specific in the siginfo structure then it should
2165 * have updated *info via PTRACE_SETSIGINFO.
2166 */
2167 if (signr != info->si_signo) {
2168 info->si_signo = signr;
2169 info->si_errno = 0;
2170 info->si_code = SI_USER;
2171 rcu_read_lock();
2172 info->si_pid = task_pid_vnr(current->parent);
2173 info->si_uid = from_kuid_munged(current_user_ns(),
2174 task_uid(current->parent));
2175 rcu_read_unlock();
2176 }
2177
2178 /* If the (new) signal is now blocked, requeue it. */
2179 if (sigismember(¤t->blocked, signr)) {
2180 specific_send_sig_info(signr, info, current);
2181 signr = 0;
2182 }
2183
2184 return signr;
2185}
2186
2187int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2188 struct pt_regs *regs, void *cookie)
2189{
2190 struct sighand_struct *sighand = current->sighand;
2191 struct signal_struct *signal = current->signal;
2192 int signr;
2193
2194 if (unlikely(uprobe_deny_signal()))
2195 return 0;
2196
2197relock:
2198 /*
2199 * We'll jump back here after any time we were stopped in TASK_STOPPED.
2200 * While in TASK_STOPPED, we were considered "frozen enough".
2201 * Now that we woke up, it's crucial if we're supposed to be
2202 * frozen that we freeze now before running anything substantial.
2203 */
2204 try_to_freeze();
2205
2206 spin_lock_irq(&sighand->siglock);
2207 /*
2208 * Every stopped thread goes here after wakeup. Check to see if
2209 * we should notify the parent, prepare_signal(SIGCONT) encodes
2210 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2211 */
2212 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2213 int why;
2214
2215 if (signal->flags & SIGNAL_CLD_CONTINUED)
2216 why = CLD_CONTINUED;
2217 else
2218 why = CLD_STOPPED;
2219
2220 signal->flags &= ~SIGNAL_CLD_MASK;
2221
2222 spin_unlock_irq(&sighand->siglock);
2223
2224 /*
2225 * Notify the parent that we're continuing. This event is
2226 * always per-process and doesn't make whole lot of sense
2227 * for ptracers, who shouldn't consume the state via
2228 * wait(2) either, but, for backward compatibility, notify
2229 * the ptracer of the group leader too unless it's gonna be
2230 * a duplicate.
2231 */
2232 read_lock(&tasklist_lock);
2233 do_notify_parent_cldstop(current, false, why);
2234
2235 if (ptrace_reparented(current->group_leader))
2236 do_notify_parent_cldstop(current->group_leader,
2237 true, why);
2238 read_unlock(&tasklist_lock);
2239
2240 goto relock;
2241 }
2242
2243 for (;;) {
2244 struct k_sigaction *ka;
2245
2246 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2247 do_signal_stop(0))
2248 goto relock;
2249
2250 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2251 do_jobctl_trap();
2252 spin_unlock_irq(&sighand->siglock);
2253 goto relock;
2254 }
2255
2256 signr = dequeue_signal(current, ¤t->blocked, info);
2257
2258 if (!signr)
2259 break; /* will return 0 */
2260
2261 if (unlikely(current->ptrace) && signr != SIGKILL) {
2262 signr = ptrace_signal(signr, info,
2263 regs, cookie);
2264 if (!signr)
2265 continue;
2266 }
2267
2268 ka = &sighand->action[signr-1];
2269
2270 /* Trace actually delivered signals. */
2271 trace_signal_deliver(signr, info, ka);
2272
2273 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2274 continue;
2275 if (ka->sa.sa_handler != SIG_DFL) {
2276 /* Run the handler. */
2277 *return_ka = *ka;
2278
2279 if (ka->sa.sa_flags & SA_ONESHOT)
2280 ka->sa.sa_handler = SIG_DFL;
2281
2282 break; /* will return non-zero "signr" value */
2283 }
2284
2285 /*
2286 * Now we are doing the default action for this signal.
2287 */
2288 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2289 continue;
2290
2291 /*
2292 * Global init gets no signals it doesn't want.
2293 * Container-init gets no signals it doesn't want from same
2294 * container.
2295 *
2296 * Note that if global/container-init sees a sig_kernel_only()
2297 * signal here, the signal must have been generated internally
2298 * or must have come from an ancestor namespace. In either
2299 * case, the signal cannot be dropped.
2300 */
2301 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2302 !sig_kernel_only(signr))
2303 continue;
2304
2305 if (sig_kernel_stop(signr)) {
2306 /*
2307 * The default action is to stop all threads in
2308 * the thread group. The job control signals
2309 * do nothing in an orphaned pgrp, but SIGSTOP
2310 * always works. Note that siglock needs to be
2311 * dropped during the call to is_orphaned_pgrp()
2312 * because of lock ordering with tasklist_lock.
2313 * This allows an intervening SIGCONT to be posted.
2314 * We need to check for that and bail out if necessary.
2315 */
2316 if (signr != SIGSTOP) {
2317 spin_unlock_irq(&sighand->siglock);
2318
2319 /* signals can be posted during this window */
2320
2321 if (is_current_pgrp_orphaned())
2322 goto relock;
2323
2324 spin_lock_irq(&sighand->siglock);
2325 }
2326
2327 if (likely(do_signal_stop(info->si_signo))) {
2328 /* It released the siglock. */
2329 goto relock;
2330 }
2331
2332 /*
2333 * We didn't actually stop, due to a race
2334 * with SIGCONT or something like that.
2335 */
2336 continue;
2337 }
2338
2339 spin_unlock_irq(&sighand->siglock);
2340
2341 /*
2342 * Anything else is fatal, maybe with a core dump.
2343 */
2344 current->flags |= PF_SIGNALED;
2345
2346 if (sig_kernel_coredump(signr)) {
2347 if (print_fatal_signals)
2348 print_fatal_signal(regs, info->si_signo);
2349 /*
2350 * If it was able to dump core, this kills all
2351 * other threads in the group and synchronizes with
2352 * their demise. If we lost the race with another
2353 * thread getting here, it set group_exit_code
2354 * first and our do_group_exit call below will use
2355 * that value and ignore the one we pass it.
2356 */
2357 do_coredump(info->si_signo, info->si_signo, regs);
2358 }
2359
2360 /*
2361 * Death signals, no core dump.
2362 */
2363 do_group_exit(info->si_signo);
2364 /* NOTREACHED */
2365 }
2366 spin_unlock_irq(&sighand->siglock);
2367 return signr;
2368}
2369
2370/**
2371 * signal_delivered -
2372 * @sig: number of signal being delivered
2373 * @info: siginfo_t of signal being delivered
2374 * @ka: sigaction setting that chose the handler
2375 * @regs: user register state
2376 * @stepping: nonzero if debugger single-step or block-step in use
2377 *
2378 * This function should be called when a signal has succesfully been
2379 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2380 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2381 * is set in @ka->sa.sa_flags. Tracing is notified.
2382 */
2383void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2384 struct pt_regs *regs, int stepping)
2385{
2386 sigset_t blocked;
2387
2388 /* A signal was successfully delivered, and the
2389 saved sigmask was stored on the signal frame,
2390 and will be restored by sigreturn. So we can
2391 simply clear the restore sigmask flag. */
2392 clear_restore_sigmask();
2393
2394 sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
2395 if (!(ka->sa.sa_flags & SA_NODEFER))
2396 sigaddset(&blocked, sig);
2397 set_current_blocked(&blocked);
2398 tracehook_signal_handler(sig, info, ka, regs, stepping);
2399}
2400
2401/*
2402 * It could be that complete_signal() picked us to notify about the
2403 * group-wide signal. Other threads should be notified now to take
2404 * the shared signals in @which since we will not.
2405 */
2406static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2407{
2408 sigset_t retarget;
2409 struct task_struct *t;
2410
2411 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2412 if (sigisemptyset(&retarget))
2413 return;
2414
2415 t = tsk;
2416 while_each_thread(tsk, t) {
2417 if (t->flags & PF_EXITING)
2418 continue;
2419
2420 if (!has_pending_signals(&retarget, &t->blocked))
2421 continue;
2422 /* Remove the signals this thread can handle. */
2423 sigandsets(&retarget, &retarget, &t->blocked);
2424
2425 if (!signal_pending(t))
2426 signal_wake_up(t, 0);
2427
2428 if (sigisemptyset(&retarget))
2429 break;
2430 }
2431}
2432
2433void exit_signals(struct task_struct *tsk)
2434{
2435 int group_stop = 0;
2436 sigset_t unblocked;
2437
2438 /*
2439 * @tsk is about to have PF_EXITING set - lock out users which
2440 * expect stable threadgroup.
2441 */
2442 threadgroup_change_begin(tsk);
2443
2444 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2445 tsk->flags |= PF_EXITING;
2446 threadgroup_change_end(tsk);
2447 return;
2448 }
2449
2450 spin_lock_irq(&tsk->sighand->siglock);
2451 /*
2452 * From now this task is not visible for group-wide signals,
2453 * see wants_signal(), do_signal_stop().
2454 */
2455 tsk->flags |= PF_EXITING;
2456
2457 threadgroup_change_end(tsk);
2458
2459 if (!signal_pending(tsk))
2460 goto out;
2461
2462 unblocked = tsk->blocked;
2463 signotset(&unblocked);
2464 retarget_shared_pending(tsk, &unblocked);
2465
2466 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2467 task_participate_group_stop(tsk))
2468 group_stop = CLD_STOPPED;
2469out:
2470 spin_unlock_irq(&tsk->sighand->siglock);
2471
2472 /*
2473 * If group stop has completed, deliver the notification. This
2474 * should always go to the real parent of the group leader.
2475 */
2476 if (unlikely(group_stop)) {
2477 read_lock(&tasklist_lock);
2478 do_notify_parent_cldstop(tsk, false, group_stop);
2479 read_unlock(&tasklist_lock);
2480 }
2481}
2482
2483EXPORT_SYMBOL(recalc_sigpending);
2484EXPORT_SYMBOL_GPL(dequeue_signal);
2485EXPORT_SYMBOL(flush_signals);
2486EXPORT_SYMBOL(force_sig);
2487EXPORT_SYMBOL(send_sig);
2488EXPORT_SYMBOL(send_sig_info);
2489EXPORT_SYMBOL(sigprocmask);
2490EXPORT_SYMBOL(block_all_signals);
2491EXPORT_SYMBOL(unblock_all_signals);
2492
2493
2494/*
2495 * System call entry points.
2496 */
2497
2498/**
2499 * sys_restart_syscall - restart a system call
2500 */
2501SYSCALL_DEFINE0(restart_syscall)
2502{
2503 struct restart_block *restart = ¤t_thread_info()->restart_block;
2504 return restart->fn(restart);
2505}
2506
2507long do_no_restart_syscall(struct restart_block *param)
2508{
2509 return -EINTR;
2510}
2511
2512static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2513{
2514 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2515 sigset_t newblocked;
2516 /* A set of now blocked but previously unblocked signals. */
2517 sigandnsets(&newblocked, newset, ¤t->blocked);
2518 retarget_shared_pending(tsk, &newblocked);
2519 }
2520 tsk->blocked = *newset;
2521 recalc_sigpending();
2522}
2523
2524/**
2525 * set_current_blocked - change current->blocked mask
2526 * @newset: new mask
2527 *
2528 * It is wrong to change ->blocked directly, this helper should be used
2529 * to ensure the process can't miss a shared signal we are going to block.
2530 */
2531void set_current_blocked(sigset_t *newset)
2532{
2533 struct task_struct *tsk = current;
2534 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2535 spin_lock_irq(&tsk->sighand->siglock);
2536 __set_task_blocked(tsk, newset);
2537 spin_unlock_irq(&tsk->sighand->siglock);
2538}
2539
2540void __set_current_blocked(const sigset_t *newset)
2541{
2542 struct task_struct *tsk = current;
2543
2544 spin_lock_irq(&tsk->sighand->siglock);
2545 __set_task_blocked(tsk, newset);
2546 spin_unlock_irq(&tsk->sighand->siglock);
2547}
2548
2549/*
2550 * This is also useful for kernel threads that want to temporarily
2551 * (or permanently) block certain signals.
2552 *
2553 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2554 * interface happily blocks "unblockable" signals like SIGKILL
2555 * and friends.
2556 */
2557int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2558{
2559 struct task_struct *tsk = current;
2560 sigset_t newset;
2561
2562 /* Lockless, only current can change ->blocked, never from irq */
2563 if (oldset)
2564 *oldset = tsk->blocked;
2565
2566 switch (how) {
2567 case SIG_BLOCK:
2568 sigorsets(&newset, &tsk->blocked, set);
2569 break;
2570 case SIG_UNBLOCK:
2571 sigandnsets(&newset, &tsk->blocked, set);
2572 break;
2573 case SIG_SETMASK:
2574 newset = *set;
2575 break;
2576 default:
2577 return -EINVAL;
2578 }
2579
2580 __set_current_blocked(&newset);
2581 return 0;
2582}
2583
2584/**
2585 * sys_rt_sigprocmask - change the list of currently blocked signals
2586 * @how: whether to add, remove, or set signals
2587 * @nset: stores pending signals
2588 * @oset: previous value of signal mask if non-null
2589 * @sigsetsize: size of sigset_t type
2590 */
2591SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2592 sigset_t __user *, oset, size_t, sigsetsize)
2593{
2594 sigset_t old_set, new_set;
2595 int error;
2596
2597 /* XXX: Don't preclude handling different sized sigset_t's. */
2598 if (sigsetsize != sizeof(sigset_t))
2599 return -EINVAL;
2600
2601 old_set = current->blocked;
2602
2603 if (nset) {
2604 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2605 return -EFAULT;
2606 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2607
2608 error = sigprocmask(how, &new_set, NULL);
2609 if (error)
2610 return error;
2611 }
2612
2613 if (oset) {
2614 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2615 return -EFAULT;
2616 }
2617
2618 return 0;
2619}
2620
2621long do_sigpending(void __user *set, unsigned long sigsetsize)
2622{
2623 long error = -EINVAL;
2624 sigset_t pending;
2625
2626 if (sigsetsize > sizeof(sigset_t))
2627 goto out;
2628
2629 spin_lock_irq(¤t->sighand->siglock);
2630 sigorsets(&pending, ¤t->pending.signal,
2631 ¤t->signal->shared_pending.signal);
2632 spin_unlock_irq(¤t->sighand->siglock);
2633
2634 /* Outside the lock because only this thread touches it. */
2635 sigandsets(&pending, ¤t->blocked, &pending);
2636
2637 error = -EFAULT;
2638 if (!copy_to_user(set, &pending, sigsetsize))
2639 error = 0;
2640
2641out:
2642 return error;
2643}
2644
2645/**
2646 * sys_rt_sigpending - examine a pending signal that has been raised
2647 * while blocked
2648 * @set: stores pending signals
2649 * @sigsetsize: size of sigset_t type or larger
2650 */
2651SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
2652{
2653 return do_sigpending(set, sigsetsize);
2654}
2655
2656#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2657
2658int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2659{
2660 int err;
2661
2662 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2663 return -EFAULT;
2664 if (from->si_code < 0)
2665 return __copy_to_user(to, from, sizeof(siginfo_t))
2666 ? -EFAULT : 0;
2667 /*
2668 * If you change siginfo_t structure, please be sure
2669 * this code is fixed accordingly.
2670 * Please remember to update the signalfd_copyinfo() function
2671 * inside fs/signalfd.c too, in case siginfo_t changes.
2672 * It should never copy any pad contained in the structure
2673 * to avoid security leaks, but must copy the generic
2674 * 3 ints plus the relevant union member.
2675 */
2676 err = __put_user(from->si_signo, &to->si_signo);
2677 err |= __put_user(from->si_errno, &to->si_errno);
2678 err |= __put_user((short)from->si_code, &to->si_code);
2679 switch (from->si_code & __SI_MASK) {
2680 case __SI_KILL:
2681 err |= __put_user(from->si_pid, &to->si_pid);
2682 err |= __put_user(from->si_uid, &to->si_uid);
2683 break;
2684 case __SI_TIMER:
2685 err |= __put_user(from->si_tid, &to->si_tid);
2686 err |= __put_user(from->si_overrun, &to->si_overrun);
2687 err |= __put_user(from->si_ptr, &to->si_ptr);
2688 break;
2689 case __SI_POLL:
2690 err |= __put_user(from->si_band, &to->si_band);
2691 err |= __put_user(from->si_fd, &to->si_fd);
2692 break;
2693 case __SI_FAULT:
2694 err |= __put_user(from->si_addr, &to->si_addr);
2695#ifdef __ARCH_SI_TRAPNO
2696 err |= __put_user(from->si_trapno, &to->si_trapno);
2697#endif
2698#ifdef BUS_MCEERR_AO
2699 /*
2700 * Other callers might not initialize the si_lsb field,
2701 * so check explicitly for the right codes here.
2702 */
2703 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2704 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2705#endif
2706 break;
2707 case __SI_CHLD:
2708 err |= __put_user(from->si_pid, &to->si_pid);
2709 err |= __put_user(from->si_uid, &to->si_uid);
2710 err |= __put_user(from->si_status, &to->si_status);
2711 err |= __put_user(from->si_utime, &to->si_utime);
2712 err |= __put_user(from->si_stime, &to->si_stime);
2713 break;
2714 case __SI_RT: /* This is not generated by the kernel as of now. */
2715 case __SI_MESGQ: /* But this is */
2716 err |= __put_user(from->si_pid, &to->si_pid);
2717 err |= __put_user(from->si_uid, &to->si_uid);
2718 err |= __put_user(from->si_ptr, &to->si_ptr);
2719 break;
2720#ifdef __ARCH_SIGSYS
2721 case __SI_SYS:
2722 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2723 err |= __put_user(from->si_syscall, &to->si_syscall);
2724 err |= __put_user(from->si_arch, &to->si_arch);
2725 break;
2726#endif
2727 default: /* this is just in case for now ... */
2728 err |= __put_user(from->si_pid, &to->si_pid);
2729 err |= __put_user(from->si_uid, &to->si_uid);
2730 break;
2731 }
2732 return err;
2733}
2734
2735#endif
2736
2737/**
2738 * do_sigtimedwait - wait for queued signals specified in @which
2739 * @which: queued signals to wait for
2740 * @info: if non-null, the signal's siginfo is returned here
2741 * @ts: upper bound on process time suspension
2742 */
2743int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2744 const struct timespec *ts)
2745{
2746 struct task_struct *tsk = current;
2747 long timeout = MAX_SCHEDULE_TIMEOUT;
2748 sigset_t mask = *which;
2749 int sig;
2750
2751 if (ts) {
2752 if (!timespec_valid(ts))
2753 return -EINVAL;
2754 timeout = timespec_to_jiffies(ts);
2755 /*
2756 * We can be close to the next tick, add another one
2757 * to ensure we will wait at least the time asked for.
2758 */
2759 if (ts->tv_sec || ts->tv_nsec)
2760 timeout++;
2761 }
2762
2763 /*
2764 * Invert the set of allowed signals to get those we want to block.
2765 */
2766 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2767 signotset(&mask);
2768
2769 spin_lock_irq(&tsk->sighand->siglock);
2770 sig = dequeue_signal(tsk, &mask, info);
2771 if (!sig && timeout) {
2772 /*
2773 * None ready, temporarily unblock those we're interested
2774 * while we are sleeping in so that we'll be awakened when
2775 * they arrive. Unblocking is always fine, we can avoid
2776 * set_current_blocked().
2777 */
2778 tsk->real_blocked = tsk->blocked;
2779 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2780 recalc_sigpending();
2781 spin_unlock_irq(&tsk->sighand->siglock);
2782
2783 timeout = schedule_timeout_interruptible(timeout);
2784
2785 spin_lock_irq(&tsk->sighand->siglock);
2786 __set_task_blocked(tsk, &tsk->real_blocked);
2787 siginitset(&tsk->real_blocked, 0);
2788 sig = dequeue_signal(tsk, &mask, info);
2789 }
2790 spin_unlock_irq(&tsk->sighand->siglock);
2791
2792 if (sig)
2793 return sig;
2794 return timeout ? -EINTR : -EAGAIN;
2795}
2796
2797/**
2798 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2799 * in @uthese
2800 * @uthese: queued signals to wait for
2801 * @uinfo: if non-null, the signal's siginfo is returned here
2802 * @uts: upper bound on process time suspension
2803 * @sigsetsize: size of sigset_t type
2804 */
2805SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2806 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2807 size_t, sigsetsize)
2808{
2809 sigset_t these;
2810 struct timespec ts;
2811 siginfo_t info;
2812 int ret;
2813
2814 /* XXX: Don't preclude handling different sized sigset_t's. */
2815 if (sigsetsize != sizeof(sigset_t))
2816 return -EINVAL;
2817
2818 if (copy_from_user(&these, uthese, sizeof(these)))
2819 return -EFAULT;
2820
2821 if (uts) {
2822 if (copy_from_user(&ts, uts, sizeof(ts)))
2823 return -EFAULT;
2824 }
2825
2826 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2827
2828 if (ret > 0 && uinfo) {
2829 if (copy_siginfo_to_user(uinfo, &info))
2830 ret = -EFAULT;
2831 }
2832
2833 return ret;
2834}
2835
2836/**
2837 * sys_kill - send a signal to a process
2838 * @pid: the PID of the process
2839 * @sig: signal to be sent
2840 */
2841SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2842{
2843 struct siginfo info;
2844
2845 info.si_signo = sig;
2846 info.si_errno = 0;
2847 info.si_code = SI_USER;
2848 info.si_pid = task_tgid_vnr(current);
2849 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2850
2851 return kill_something_info(sig, &info, pid);
2852}
2853
2854static int
2855do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2856{
2857 struct task_struct *p;
2858 int error = -ESRCH;
2859
2860 rcu_read_lock();
2861 p = find_task_by_vpid(pid);
2862 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2863 error = check_kill_permission(sig, info, p);
2864 /*
2865 * The null signal is a permissions and process existence
2866 * probe. No signal is actually delivered.
2867 */
2868 if (!error && sig) {
2869 error = do_send_sig_info(sig, info, p, false);
2870 /*
2871 * If lock_task_sighand() failed we pretend the task
2872 * dies after receiving the signal. The window is tiny,
2873 * and the signal is private anyway.
2874 */
2875 if (unlikely(error == -ESRCH))
2876 error = 0;
2877 }
2878 }
2879 rcu_read_unlock();
2880
2881 return error;
2882}
2883
2884static int do_tkill(pid_t tgid, pid_t pid, int sig)
2885{
2886 struct siginfo info;
2887
2888 info.si_signo = sig;
2889 info.si_errno = 0;
2890 info.si_code = SI_TKILL;
2891 info.si_pid = task_tgid_vnr(current);
2892 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2893
2894 return do_send_specific(tgid, pid, sig, &info);
2895}
2896
2897/**
2898 * sys_tgkill - send signal to one specific thread
2899 * @tgid: the thread group ID of the thread
2900 * @pid: the PID of the thread
2901 * @sig: signal to be sent
2902 *
2903 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2904 * exists but it's not belonging to the target process anymore. This
2905 * method solves the problem of threads exiting and PIDs getting reused.
2906 */
2907SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2908{
2909 /* This is only valid for single tasks */
2910 if (pid <= 0 || tgid <= 0)
2911 return -EINVAL;
2912
2913 return do_tkill(tgid, pid, sig);
2914}
2915
2916/**
2917 * sys_tkill - send signal to one specific task
2918 * @pid: the PID of the task
2919 * @sig: signal to be sent
2920 *
2921 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2922 */
2923SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2924{
2925 /* This is only valid for single tasks */
2926 if (pid <= 0)
2927 return -EINVAL;
2928
2929 return do_tkill(0, pid, sig);
2930}
2931
2932/**
2933 * sys_rt_sigqueueinfo - send signal information to a signal
2934 * @pid: the PID of the thread
2935 * @sig: signal to be sent
2936 * @uinfo: signal info to be sent
2937 */
2938SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2939 siginfo_t __user *, uinfo)
2940{
2941 siginfo_t info;
2942
2943 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2944 return -EFAULT;
2945
2946 /* Not even root can pretend to send signals from the kernel.
2947 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2948 */
2949 if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2950 /* We used to allow any < 0 si_code */
2951 WARN_ON_ONCE(info.si_code < 0);
2952 return -EPERM;
2953 }
2954 info.si_signo = sig;
2955
2956 /* POSIX.1b doesn't mention process groups. */
2957 return kill_proc_info(sig, &info, pid);
2958}
2959
2960long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2961{
2962 /* This is only valid for single tasks */
2963 if (pid <= 0 || tgid <= 0)
2964 return -EINVAL;
2965
2966 /* Not even root can pretend to send signals from the kernel.
2967 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2968 */
2969 if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2970 /* We used to allow any < 0 si_code */
2971 WARN_ON_ONCE(info->si_code < 0);
2972 return -EPERM;
2973 }
2974 info->si_signo = sig;
2975
2976 return do_send_specific(tgid, pid, sig, info);
2977}
2978
2979SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
2980 siginfo_t __user *, uinfo)
2981{
2982 siginfo_t info;
2983
2984 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2985 return -EFAULT;
2986
2987 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
2988}
2989
2990int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2991{
2992 struct task_struct *t = current;
2993 struct k_sigaction *k;
2994 sigset_t mask;
2995
2996 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2997 return -EINVAL;
2998
2999 k = &t->sighand->action[sig-1];
3000
3001 spin_lock_irq(¤t->sighand->siglock);
3002 if (oact)
3003 *oact = *k;
3004
3005 if (act) {
3006 sigdelsetmask(&act->sa.sa_mask,
3007 sigmask(SIGKILL) | sigmask(SIGSTOP));
3008 *k = *act;
3009 /*
3010 * POSIX 3.3.1.3:
3011 * "Setting a signal action to SIG_IGN for a signal that is
3012 * pending shall cause the pending signal to be discarded,
3013 * whether or not it is blocked."
3014 *
3015 * "Setting a signal action to SIG_DFL for a signal that is
3016 * pending and whose default action is to ignore the signal
3017 * (for example, SIGCHLD), shall cause the pending signal to
3018 * be discarded, whether or not it is blocked"
3019 */
3020 if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3021 sigemptyset(&mask);
3022 sigaddset(&mask, sig);
3023 rm_from_queue_full(&mask, &t->signal->shared_pending);
3024 do {
3025 rm_from_queue_full(&mask, &t->pending);
3026 t = next_thread(t);
3027 } while (t != current);
3028 }
3029 }
3030
3031 spin_unlock_irq(¤t->sighand->siglock);
3032 return 0;
3033}
3034
3035int
3036do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3037{
3038 stack_t oss;
3039 int error;
3040
3041 oss.ss_sp = (void __user *) current->sas_ss_sp;
3042 oss.ss_size = current->sas_ss_size;
3043 oss.ss_flags = sas_ss_flags(sp);
3044
3045 if (uss) {
3046 void __user *ss_sp;
3047 size_t ss_size;
3048 int ss_flags;
3049
3050 error = -EFAULT;
3051 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3052 goto out;
3053 error = __get_user(ss_sp, &uss->ss_sp) |
3054 __get_user(ss_flags, &uss->ss_flags) |
3055 __get_user(ss_size, &uss->ss_size);
3056 if (error)
3057 goto out;
3058
3059 error = -EPERM;
3060 if (on_sig_stack(sp))
3061 goto out;
3062
3063 error = -EINVAL;
3064 /*
3065 * Note - this code used to test ss_flags incorrectly:
3066 * old code may have been written using ss_flags==0
3067 * to mean ss_flags==SS_ONSTACK (as this was the only
3068 * way that worked) - this fix preserves that older
3069 * mechanism.
3070 */
3071 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3072 goto out;
3073
3074 if (ss_flags == SS_DISABLE) {
3075 ss_size = 0;
3076 ss_sp = NULL;
3077 } else {
3078 error = -ENOMEM;
3079 if (ss_size < MINSIGSTKSZ)
3080 goto out;
3081 }
3082
3083 current->sas_ss_sp = (unsigned long) ss_sp;
3084 current->sas_ss_size = ss_size;
3085 }
3086
3087 error = 0;
3088 if (uoss) {
3089 error = -EFAULT;
3090 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3091 goto out;
3092 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3093 __put_user(oss.ss_size, &uoss->ss_size) |
3094 __put_user(oss.ss_flags, &uoss->ss_flags);
3095 }
3096
3097out:
3098 return error;
3099}
3100
3101#ifdef __ARCH_WANT_SYS_SIGPENDING
3102
3103/**
3104 * sys_sigpending - examine pending signals
3105 * @set: where mask of pending signal is returned
3106 */
3107SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3108{
3109 return do_sigpending(set, sizeof(*set));
3110}
3111
3112#endif
3113
3114#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3115/**
3116 * sys_sigprocmask - examine and change blocked signals
3117 * @how: whether to add, remove, or set signals
3118 * @nset: signals to add or remove (if non-null)
3119 * @oset: previous value of signal mask if non-null
3120 *
3121 * Some platforms have their own version with special arguments;
3122 * others support only sys_rt_sigprocmask.
3123 */
3124
3125SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3126 old_sigset_t __user *, oset)
3127{
3128 old_sigset_t old_set, new_set;
3129 sigset_t new_blocked;
3130
3131 old_set = current->blocked.sig[0];
3132
3133 if (nset) {
3134 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3135 return -EFAULT;
3136 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
3137
3138 new_blocked = current->blocked;
3139
3140 switch (how) {
3141 case SIG_BLOCK:
3142 sigaddsetmask(&new_blocked, new_set);
3143 break;
3144 case SIG_UNBLOCK:
3145 sigdelsetmask(&new_blocked, new_set);
3146 break;
3147 case SIG_SETMASK:
3148 new_blocked.sig[0] = new_set;
3149 break;
3150 default:
3151 return -EINVAL;
3152 }
3153
3154 __set_current_blocked(&new_blocked);
3155 }
3156
3157 if (oset) {
3158 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3159 return -EFAULT;
3160 }
3161
3162 return 0;
3163}
3164#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3165
3166#ifdef __ARCH_WANT_SYS_RT_SIGACTION
3167/**
3168 * sys_rt_sigaction - alter an action taken by a process
3169 * @sig: signal to be sent
3170 * @act: new sigaction
3171 * @oact: used to save the previous sigaction
3172 * @sigsetsize: size of sigset_t type
3173 */
3174SYSCALL_DEFINE4(rt_sigaction, int, sig,
3175 const struct sigaction __user *, act,
3176 struct sigaction __user *, oact,
3177 size_t, sigsetsize)
3178{
3179 struct k_sigaction new_sa, old_sa;
3180 int ret = -EINVAL;
3181
3182 /* XXX: Don't preclude handling different sized sigset_t's. */
3183 if (sigsetsize != sizeof(sigset_t))
3184 goto out;
3185
3186 if (act) {
3187 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3188 return -EFAULT;
3189 }
3190
3191 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3192
3193 if (!ret && oact) {
3194 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3195 return -EFAULT;
3196 }
3197out:
3198 return ret;
3199}
3200#endif /* __ARCH_WANT_SYS_RT_SIGACTION */
3201
3202#ifdef __ARCH_WANT_SYS_SGETMASK
3203
3204/*
3205 * For backwards compatibility. Functionality superseded by sigprocmask.
3206 */
3207SYSCALL_DEFINE0(sgetmask)
3208{
3209 /* SMP safe */
3210 return current->blocked.sig[0];
3211}
3212
3213SYSCALL_DEFINE1(ssetmask, int, newmask)
3214{
3215 int old = current->blocked.sig[0];
3216 sigset_t newset;
3217
3218 set_current_blocked(&newset);
3219
3220 return old;
3221}
3222#endif /* __ARCH_WANT_SGETMASK */
3223
3224#ifdef __ARCH_WANT_SYS_SIGNAL
3225/*
3226 * For backwards compatibility. Functionality superseded by sigaction.
3227 */
3228SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3229{
3230 struct k_sigaction new_sa, old_sa;
3231 int ret;
3232
3233 new_sa.sa.sa_handler = handler;
3234 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3235 sigemptyset(&new_sa.sa.sa_mask);
3236
3237 ret = do_sigaction(sig, &new_sa, &old_sa);
3238
3239 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3240}
3241#endif /* __ARCH_WANT_SYS_SIGNAL */
3242
3243#ifdef __ARCH_WANT_SYS_PAUSE
3244
3245SYSCALL_DEFINE0(pause)
3246{
3247 while (!signal_pending(current)) {
3248 current->state = TASK_INTERRUPTIBLE;
3249 schedule();
3250 }
3251 return -ERESTARTNOHAND;
3252}
3253
3254#endif
3255
3256int sigsuspend(sigset_t *set)
3257{
3258 current->saved_sigmask = current->blocked;
3259 set_current_blocked(set);
3260
3261 current->state = TASK_INTERRUPTIBLE;
3262 schedule();
3263 set_restore_sigmask();
3264 return -ERESTARTNOHAND;
3265}
3266
3267#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3268/**
3269 * sys_rt_sigsuspend - replace the signal mask for a value with the
3270 * @unewset value until a signal is received
3271 * @unewset: new signal mask value
3272 * @sigsetsize: size of sigset_t type
3273 */
3274SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3275{
3276 sigset_t newset;
3277
3278 /* XXX: Don't preclude handling different sized sigset_t's. */
3279 if (sigsetsize != sizeof(sigset_t))
3280 return -EINVAL;
3281
3282 if (copy_from_user(&newset, unewset, sizeof(newset)))
3283 return -EFAULT;
3284 return sigsuspend(&newset);
3285}
3286#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
3287
3288__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3289{
3290 return NULL;
3291}
3292
3293void __init signals_init(void)
3294{
3295 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3296}
3297
3298#ifdef CONFIG_KGDB_KDB
3299#include <linux/kdb.h>
3300/*
3301 * kdb_send_sig_info - Allows kdb to send signals without exposing
3302 * signal internals. This function checks if the required locks are
3303 * available before calling the main signal code, to avoid kdb
3304 * deadlocks.
3305 */
3306void
3307kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3308{
3309 static struct task_struct *kdb_prev_t;
3310 int sig, new_t;
3311 if (!spin_trylock(&t->sighand->siglock)) {
3312 kdb_printf("Can't do kill command now.\n"
3313 "The sigmask lock is held somewhere else in "
3314 "kernel, try again later\n");
3315 return;
3316 }
3317 spin_unlock(&t->sighand->siglock);
3318 new_t = kdb_prev_t != t;
3319 kdb_prev_t = t;
3320 if (t->state != TASK_RUNNING && new_t) {
3321 kdb_printf("Process is not RUNNING, sending a signal from "
3322 "kdb risks deadlock\n"
3323 "on the run queue locks. "
3324 "The signal has _not_ been sent.\n"
3325 "Reissue the kill command if you want to risk "
3326 "the deadlock.\n");
3327 return;
3328 }
3329 sig = info->si_signo;
3330 if (send_sig_info(sig, info, t))
3331 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3332 sig, t->pid);
3333 else
3334 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3335}
3336#endif /* CONFIG_KGDB_KDB */