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1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/coredump.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/ptrace.h>
24#include <linux/signal.h>
25#include <linux/signalfd.h>
26#include <linux/ratelimit.h>
27#include <linux/tracehook.h>
28#include <linux/capability.h>
29#include <linux/freezer.h>
30#include <linux/pid_namespace.h>
31#include <linux/nsproxy.h>
32#include <linux/user_namespace.h>
33#include <linux/uprobes.h>
34#include <linux/compat.h>
35#include <linux/cn_proc.h>
36#include <linux/compiler.h>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <linux/uaccess.h>
43#include <asm/unistd.h>
44#include <asm/siginfo.h>
45#include <asm/cacheflush.h>
46#include "audit.h" /* audit_signal_info() */
47
48/*
49 * SLAB caches for signal bits.
50 */
51
52static struct kmem_cache *sigqueue_cachep;
53
54int print_fatal_signals __read_mostly;
55
56static void __user *sig_handler(struct task_struct *t, int sig)
57{
58 return t->sighand->action[sig - 1].sa.sa_handler;
59}
60
61static int sig_handler_ignored(void __user *handler, int sig)
62{
63 /* Is it explicitly or implicitly ignored? */
64 return handler == SIG_IGN ||
65 (handler == SIG_DFL && sig_kernel_ignore(sig));
66}
67
68static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69{
70 void __user *handler;
71
72 handler = sig_handler(t, sig);
73
74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 handler == SIG_DFL && !force)
76 return 1;
77
78 return sig_handler_ignored(handler, sig);
79}
80
81static int sig_ignored(struct task_struct *t, int sig, bool force)
82{
83 /*
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
86 * unblocked.
87 */
88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 return 0;
90
91 if (!sig_task_ignored(t, sig, force))
92 return 0;
93
94 /*
95 * Tracers may want to know about even ignored signals.
96 */
97 return !t->ptrace;
98}
99
100/*
101 * Re-calculate pending state from the set of locally pending
102 * signals, globally pending signals, and blocked signals.
103 */
104static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105{
106 unsigned long ready;
107 long i;
108
109 switch (_NSIG_WORDS) {
110 default:
111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 ready |= signal->sig[i] &~ blocked->sig[i];
113 break;
114
115 case 4: ready = signal->sig[3] &~ blocked->sig[3];
116 ready |= signal->sig[2] &~ blocked->sig[2];
117 ready |= signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
119 break;
120
121 case 2: ready = signal->sig[1] &~ blocked->sig[1];
122 ready |= signal->sig[0] &~ blocked->sig[0];
123 break;
124
125 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 }
127 return ready != 0;
128}
129
130#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131
132static int recalc_sigpending_tsk(struct task_struct *t)
133{
134 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 PENDING(&t->pending, &t->blocked) ||
136 PENDING(&t->signal->shared_pending, &t->blocked)) {
137 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 return 1;
139 }
140 /*
141 * We must never clear the flag in another thread, or in current
142 * when it's possible the current syscall is returning -ERESTART*.
143 * So we don't clear it here, and only callers who know they should do.
144 */
145 return 0;
146}
147
148/*
149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150 * This is superfluous when called on current, the wakeup is a harmless no-op.
151 */
152void recalc_sigpending_and_wake(struct task_struct *t)
153{
154 if (recalc_sigpending_tsk(t))
155 signal_wake_up(t, 0);
156}
157
158void recalc_sigpending(void)
159{
160 if (!recalc_sigpending_tsk(current) && !freezing(current))
161 clear_thread_flag(TIF_SIGPENDING);
162
163}
164
165/* Given the mask, find the first available signal that should be serviced. */
166
167#define SYNCHRONOUS_MASK \
168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170
171int next_signal(struct sigpending *pending, sigset_t *mask)
172{
173 unsigned long i, *s, *m, x;
174 int sig = 0;
175
176 s = pending->signal.sig;
177 m = mask->sig;
178
179 /*
180 * Handle the first word specially: it contains the
181 * synchronous signals that need to be dequeued first.
182 */
183 x = *s &~ *m;
184 if (x) {
185 if (x & SYNCHRONOUS_MASK)
186 x &= SYNCHRONOUS_MASK;
187 sig = ffz(~x) + 1;
188 return sig;
189 }
190
191 switch (_NSIG_WORDS) {
192 default:
193 for (i = 1; i < _NSIG_WORDS; ++i) {
194 x = *++s &~ *++m;
195 if (!x)
196 continue;
197 sig = ffz(~x) + i*_NSIG_BPW + 1;
198 break;
199 }
200 break;
201
202 case 2:
203 x = s[1] &~ m[1];
204 if (!x)
205 break;
206 sig = ffz(~x) + _NSIG_BPW + 1;
207 break;
208
209 case 1:
210 /* Nothing to do */
211 break;
212 }
213
214 return sig;
215}
216
217static inline void print_dropped_signal(int sig)
218{
219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220
221 if (!print_fatal_signals)
222 return;
223
224 if (!__ratelimit(&ratelimit_state))
225 return;
226
227 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 current->comm, current->pid, sig);
229}
230
231/**
232 * task_set_jobctl_pending - set jobctl pending bits
233 * @task: target task
234 * @mask: pending bits to set
235 *
236 * Clear @mask from @task->jobctl. @mask must be subset of
237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
239 * cleared. If @task is already being killed or exiting, this function
240 * becomes noop.
241 *
242 * CONTEXT:
243 * Must be called with @task->sighand->siglock held.
244 *
245 * RETURNS:
246 * %true if @mask is set, %false if made noop because @task was dying.
247 */
248bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
249{
250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253
254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 return false;
256
257 if (mask & JOBCTL_STOP_SIGMASK)
258 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259
260 task->jobctl |= mask;
261 return true;
262}
263
264/**
265 * task_clear_jobctl_trapping - clear jobctl trapping bit
266 * @task: target task
267 *
268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269 * Clear it and wake up the ptracer. Note that we don't need any further
270 * locking. @task->siglock guarantees that @task->parent points to the
271 * ptracer.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 */
276void task_clear_jobctl_trapping(struct task_struct *task)
277{
278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 task->jobctl &= ~JOBCTL_TRAPPING;
280 smp_mb(); /* advised by wake_up_bit() */
281 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
282 }
283}
284
285/**
286 * task_clear_jobctl_pending - clear jobctl pending bits
287 * @task: target task
288 * @mask: pending bits to clear
289 *
290 * Clear @mask from @task->jobctl. @mask must be subset of
291 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
292 * STOP bits are cleared together.
293 *
294 * If clearing of @mask leaves no stop or trap pending, this function calls
295 * task_clear_jobctl_trapping().
296 *
297 * CONTEXT:
298 * Must be called with @task->sighand->siglock held.
299 */
300void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
301{
302 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
303
304 if (mask & JOBCTL_STOP_PENDING)
305 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
306
307 task->jobctl &= ~mask;
308
309 if (!(task->jobctl & JOBCTL_PENDING_MASK))
310 task_clear_jobctl_trapping(task);
311}
312
313/**
314 * task_participate_group_stop - participate in a group stop
315 * @task: task participating in a group stop
316 *
317 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
318 * Group stop states are cleared and the group stop count is consumed if
319 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
320 * stop, the appropriate %SIGNAL_* flags are set.
321 *
322 * CONTEXT:
323 * Must be called with @task->sighand->siglock held.
324 *
325 * RETURNS:
326 * %true if group stop completion should be notified to the parent, %false
327 * otherwise.
328 */
329static bool task_participate_group_stop(struct task_struct *task)
330{
331 struct signal_struct *sig = task->signal;
332 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
333
334 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
335
336 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
337
338 if (!consume)
339 return false;
340
341 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
342 sig->group_stop_count--;
343
344 /*
345 * Tell the caller to notify completion iff we are entering into a
346 * fresh group stop. Read comment in do_signal_stop() for details.
347 */
348 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
349 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
350 return true;
351 }
352 return false;
353}
354
355/*
356 * allocate a new signal queue record
357 * - this may be called without locks if and only if t == current, otherwise an
358 * appropriate lock must be held to stop the target task from exiting
359 */
360static struct sigqueue *
361__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
362{
363 struct sigqueue *q = NULL;
364 struct user_struct *user;
365
366 /*
367 * Protect access to @t credentials. This can go away when all
368 * callers hold rcu read lock.
369 */
370 rcu_read_lock();
371 user = get_uid(__task_cred(t)->user);
372 atomic_inc(&user->sigpending);
373 rcu_read_unlock();
374
375 if (override_rlimit ||
376 atomic_read(&user->sigpending) <=
377 task_rlimit(t, RLIMIT_SIGPENDING)) {
378 q = kmem_cache_alloc(sigqueue_cachep, flags);
379 } else {
380 print_dropped_signal(sig);
381 }
382
383 if (unlikely(q == NULL)) {
384 atomic_dec(&user->sigpending);
385 free_uid(user);
386 } else {
387 INIT_LIST_HEAD(&q->list);
388 q->flags = 0;
389 q->user = user;
390 }
391
392 return q;
393}
394
395static void __sigqueue_free(struct sigqueue *q)
396{
397 if (q->flags & SIGQUEUE_PREALLOC)
398 return;
399 atomic_dec(&q->user->sigpending);
400 free_uid(q->user);
401 kmem_cache_free(sigqueue_cachep, q);
402}
403
404void flush_sigqueue(struct sigpending *queue)
405{
406 struct sigqueue *q;
407
408 sigemptyset(&queue->signal);
409 while (!list_empty(&queue->list)) {
410 q = list_entry(queue->list.next, struct sigqueue , list);
411 list_del_init(&q->list);
412 __sigqueue_free(q);
413 }
414}
415
416/*
417 * Flush all pending signals for this kthread.
418 */
419void flush_signals(struct task_struct *t)
420{
421 unsigned long flags;
422
423 spin_lock_irqsave(&t->sighand->siglock, flags);
424 clear_tsk_thread_flag(t, TIF_SIGPENDING);
425 flush_sigqueue(&t->pending);
426 flush_sigqueue(&t->signal->shared_pending);
427 spin_unlock_irqrestore(&t->sighand->siglock, flags);
428}
429
430#ifdef CONFIG_POSIX_TIMERS
431static void __flush_itimer_signals(struct sigpending *pending)
432{
433 sigset_t signal, retain;
434 struct sigqueue *q, *n;
435
436 signal = pending->signal;
437 sigemptyset(&retain);
438
439 list_for_each_entry_safe(q, n, &pending->list, list) {
440 int sig = q->info.si_signo;
441
442 if (likely(q->info.si_code != SI_TIMER)) {
443 sigaddset(&retain, sig);
444 } else {
445 sigdelset(&signal, sig);
446 list_del_init(&q->list);
447 __sigqueue_free(q);
448 }
449 }
450
451 sigorsets(&pending->signal, &signal, &retain);
452}
453
454void flush_itimer_signals(void)
455{
456 struct task_struct *tsk = current;
457 unsigned long flags;
458
459 spin_lock_irqsave(&tsk->sighand->siglock, flags);
460 __flush_itimer_signals(&tsk->pending);
461 __flush_itimer_signals(&tsk->signal->shared_pending);
462 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
463}
464#endif
465
466void ignore_signals(struct task_struct *t)
467{
468 int i;
469
470 for (i = 0; i < _NSIG; ++i)
471 t->sighand->action[i].sa.sa_handler = SIG_IGN;
472
473 flush_signals(t);
474}
475
476/*
477 * Flush all handlers for a task.
478 */
479
480void
481flush_signal_handlers(struct task_struct *t, int force_default)
482{
483 int i;
484 struct k_sigaction *ka = &t->sighand->action[0];
485 for (i = _NSIG ; i != 0 ; i--) {
486 if (force_default || ka->sa.sa_handler != SIG_IGN)
487 ka->sa.sa_handler = SIG_DFL;
488 ka->sa.sa_flags = 0;
489#ifdef __ARCH_HAS_SA_RESTORER
490 ka->sa.sa_restorer = NULL;
491#endif
492 sigemptyset(&ka->sa.sa_mask);
493 ka++;
494 }
495}
496
497int unhandled_signal(struct task_struct *tsk, int sig)
498{
499 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
500 if (is_global_init(tsk))
501 return 1;
502 if (handler != SIG_IGN && handler != SIG_DFL)
503 return 0;
504 /* if ptraced, let the tracer determine */
505 return !tsk->ptrace;
506}
507
508static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
509{
510 struct sigqueue *q, *first = NULL;
511
512 /*
513 * Collect the siginfo appropriate to this signal. Check if
514 * there is another siginfo for the same signal.
515 */
516 list_for_each_entry(q, &list->list, list) {
517 if (q->info.si_signo == sig) {
518 if (first)
519 goto still_pending;
520 first = q;
521 }
522 }
523
524 sigdelset(&list->signal, sig);
525
526 if (first) {
527still_pending:
528 list_del_init(&first->list);
529 copy_siginfo(info, &first->info);
530 __sigqueue_free(first);
531 } else {
532 /*
533 * Ok, it wasn't in the queue. This must be
534 * a fast-pathed signal or we must have been
535 * out of queue space. So zero out the info.
536 */
537 info->si_signo = sig;
538 info->si_errno = 0;
539 info->si_code = SI_USER;
540 info->si_pid = 0;
541 info->si_uid = 0;
542 }
543}
544
545static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
546 siginfo_t *info)
547{
548 int sig = next_signal(pending, mask);
549
550 if (sig)
551 collect_signal(sig, pending, info);
552 return sig;
553}
554
555/*
556 * Dequeue a signal and return the element to the caller, which is
557 * expected to free it.
558 *
559 * All callers have to hold the siglock.
560 */
561int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
562{
563 int signr;
564
565 /* We only dequeue private signals from ourselves, we don't let
566 * signalfd steal them
567 */
568 signr = __dequeue_signal(&tsk->pending, mask, info);
569 if (!signr) {
570 signr = __dequeue_signal(&tsk->signal->shared_pending,
571 mask, info);
572#ifdef CONFIG_POSIX_TIMERS
573 /*
574 * itimer signal ?
575 *
576 * itimers are process shared and we restart periodic
577 * itimers in the signal delivery path to prevent DoS
578 * attacks in the high resolution timer case. This is
579 * compliant with the old way of self-restarting
580 * itimers, as the SIGALRM is a legacy signal and only
581 * queued once. Changing the restart behaviour to
582 * restart the timer in the signal dequeue path is
583 * reducing the timer noise on heavy loaded !highres
584 * systems too.
585 */
586 if (unlikely(signr == SIGALRM)) {
587 struct hrtimer *tmr = &tsk->signal->real_timer;
588
589 if (!hrtimer_is_queued(tmr) &&
590 tsk->signal->it_real_incr != 0) {
591 hrtimer_forward(tmr, tmr->base->get_time(),
592 tsk->signal->it_real_incr);
593 hrtimer_restart(tmr);
594 }
595 }
596#endif
597 }
598
599 recalc_sigpending();
600 if (!signr)
601 return 0;
602
603 if (unlikely(sig_kernel_stop(signr))) {
604 /*
605 * Set a marker that we have dequeued a stop signal. Our
606 * caller might release the siglock and then the pending
607 * stop signal it is about to process is no longer in the
608 * pending bitmasks, but must still be cleared by a SIGCONT
609 * (and overruled by a SIGKILL). So those cases clear this
610 * shared flag after we've set it. Note that this flag may
611 * remain set after the signal we return is ignored or
612 * handled. That doesn't matter because its only purpose
613 * is to alert stop-signal processing code when another
614 * processor has come along and cleared the flag.
615 */
616 current->jobctl |= JOBCTL_STOP_DEQUEUED;
617 }
618#ifdef CONFIG_POSIX_TIMERS
619 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
620 /*
621 * Release the siglock to ensure proper locking order
622 * of timer locks outside of siglocks. Note, we leave
623 * irqs disabled here, since the posix-timers code is
624 * about to disable them again anyway.
625 */
626 spin_unlock(&tsk->sighand->siglock);
627 do_schedule_next_timer(info);
628 spin_lock(&tsk->sighand->siglock);
629 }
630#endif
631 return signr;
632}
633
634/*
635 * Tell a process that it has a new active signal..
636 *
637 * NOTE! we rely on the previous spin_lock to
638 * lock interrupts for us! We can only be called with
639 * "siglock" held, and the local interrupt must
640 * have been disabled when that got acquired!
641 *
642 * No need to set need_resched since signal event passing
643 * goes through ->blocked
644 */
645void signal_wake_up_state(struct task_struct *t, unsigned int state)
646{
647 set_tsk_thread_flag(t, TIF_SIGPENDING);
648 /*
649 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
650 * case. We don't check t->state here because there is a race with it
651 * executing another processor and just now entering stopped state.
652 * By using wake_up_state, we ensure the process will wake up and
653 * handle its death signal.
654 */
655 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
656 kick_process(t);
657}
658
659/*
660 * Remove signals in mask from the pending set and queue.
661 * Returns 1 if any signals were found.
662 *
663 * All callers must be holding the siglock.
664 */
665static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
666{
667 struct sigqueue *q, *n;
668 sigset_t m;
669
670 sigandsets(&m, mask, &s->signal);
671 if (sigisemptyset(&m))
672 return 0;
673
674 sigandnsets(&s->signal, &s->signal, mask);
675 list_for_each_entry_safe(q, n, &s->list, list) {
676 if (sigismember(mask, q->info.si_signo)) {
677 list_del_init(&q->list);
678 __sigqueue_free(q);
679 }
680 }
681 return 1;
682}
683
684static inline int is_si_special(const struct siginfo *info)
685{
686 return info <= SEND_SIG_FORCED;
687}
688
689static inline bool si_fromuser(const struct siginfo *info)
690{
691 return info == SEND_SIG_NOINFO ||
692 (!is_si_special(info) && SI_FROMUSER(info));
693}
694
695/*
696 * called with RCU read lock from check_kill_permission()
697 */
698static int kill_ok_by_cred(struct task_struct *t)
699{
700 const struct cred *cred = current_cred();
701 const struct cred *tcred = __task_cred(t);
702
703 if (uid_eq(cred->euid, tcred->suid) ||
704 uid_eq(cred->euid, tcred->uid) ||
705 uid_eq(cred->uid, tcred->suid) ||
706 uid_eq(cred->uid, tcred->uid))
707 return 1;
708
709 if (ns_capable(tcred->user_ns, CAP_KILL))
710 return 1;
711
712 return 0;
713}
714
715/*
716 * Bad permissions for sending the signal
717 * - the caller must hold the RCU read lock
718 */
719static int check_kill_permission(int sig, struct siginfo *info,
720 struct task_struct *t)
721{
722 struct pid *sid;
723 int error;
724
725 if (!valid_signal(sig))
726 return -EINVAL;
727
728 if (!si_fromuser(info))
729 return 0;
730
731 error = audit_signal_info(sig, t); /* Let audit system see the signal */
732 if (error)
733 return error;
734
735 if (!same_thread_group(current, t) &&
736 !kill_ok_by_cred(t)) {
737 switch (sig) {
738 case SIGCONT:
739 sid = task_session(t);
740 /*
741 * We don't return the error if sid == NULL. The
742 * task was unhashed, the caller must notice this.
743 */
744 if (!sid || sid == task_session(current))
745 break;
746 default:
747 return -EPERM;
748 }
749 }
750
751 return security_task_kill(t, info, sig, 0);
752}
753
754/**
755 * ptrace_trap_notify - schedule trap to notify ptracer
756 * @t: tracee wanting to notify tracer
757 *
758 * This function schedules sticky ptrace trap which is cleared on the next
759 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
760 * ptracer.
761 *
762 * If @t is running, STOP trap will be taken. If trapped for STOP and
763 * ptracer is listening for events, tracee is woken up so that it can
764 * re-trap for the new event. If trapped otherwise, STOP trap will be
765 * eventually taken without returning to userland after the existing traps
766 * are finished by PTRACE_CONT.
767 *
768 * CONTEXT:
769 * Must be called with @task->sighand->siglock held.
770 */
771static void ptrace_trap_notify(struct task_struct *t)
772{
773 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
774 assert_spin_locked(&t->sighand->siglock);
775
776 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
777 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
778}
779
780/*
781 * Handle magic process-wide effects of stop/continue signals. Unlike
782 * the signal actions, these happen immediately at signal-generation
783 * time regardless of blocking, ignoring, or handling. This does the
784 * actual continuing for SIGCONT, but not the actual stopping for stop
785 * signals. The process stop is done as a signal action for SIG_DFL.
786 *
787 * Returns true if the signal should be actually delivered, otherwise
788 * it should be dropped.
789 */
790static bool prepare_signal(int sig, struct task_struct *p, bool force)
791{
792 struct signal_struct *signal = p->signal;
793 struct task_struct *t;
794 sigset_t flush;
795
796 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
797 if (!(signal->flags & SIGNAL_GROUP_EXIT))
798 return sig == SIGKILL;
799 /*
800 * The process is in the middle of dying, nothing to do.
801 */
802 } else if (sig_kernel_stop(sig)) {
803 /*
804 * This is a stop signal. Remove SIGCONT from all queues.
805 */
806 siginitset(&flush, sigmask(SIGCONT));
807 flush_sigqueue_mask(&flush, &signal->shared_pending);
808 for_each_thread(p, t)
809 flush_sigqueue_mask(&flush, &t->pending);
810 } else if (sig == SIGCONT) {
811 unsigned int why;
812 /*
813 * Remove all stop signals from all queues, wake all threads.
814 */
815 siginitset(&flush, SIG_KERNEL_STOP_MASK);
816 flush_sigqueue_mask(&flush, &signal->shared_pending);
817 for_each_thread(p, t) {
818 flush_sigqueue_mask(&flush, &t->pending);
819 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
820 if (likely(!(t->ptrace & PT_SEIZED)))
821 wake_up_state(t, __TASK_STOPPED);
822 else
823 ptrace_trap_notify(t);
824 }
825
826 /*
827 * Notify the parent with CLD_CONTINUED if we were stopped.
828 *
829 * If we were in the middle of a group stop, we pretend it
830 * was already finished, and then continued. Since SIGCHLD
831 * doesn't queue we report only CLD_STOPPED, as if the next
832 * CLD_CONTINUED was dropped.
833 */
834 why = 0;
835 if (signal->flags & SIGNAL_STOP_STOPPED)
836 why |= SIGNAL_CLD_CONTINUED;
837 else if (signal->group_stop_count)
838 why |= SIGNAL_CLD_STOPPED;
839
840 if (why) {
841 /*
842 * The first thread which returns from do_signal_stop()
843 * will take ->siglock, notice SIGNAL_CLD_MASK, and
844 * notify its parent. See get_signal_to_deliver().
845 */
846 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
847 signal->group_stop_count = 0;
848 signal->group_exit_code = 0;
849 }
850 }
851
852 return !sig_ignored(p, sig, force);
853}
854
855/*
856 * Test if P wants to take SIG. After we've checked all threads with this,
857 * it's equivalent to finding no threads not blocking SIG. Any threads not
858 * blocking SIG were ruled out because they are not running and already
859 * have pending signals. Such threads will dequeue from the shared queue
860 * as soon as they're available, so putting the signal on the shared queue
861 * will be equivalent to sending it to one such thread.
862 */
863static inline int wants_signal(int sig, struct task_struct *p)
864{
865 if (sigismember(&p->blocked, sig))
866 return 0;
867 if (p->flags & PF_EXITING)
868 return 0;
869 if (sig == SIGKILL)
870 return 1;
871 if (task_is_stopped_or_traced(p))
872 return 0;
873 return task_curr(p) || !signal_pending(p);
874}
875
876static void complete_signal(int sig, struct task_struct *p, int group)
877{
878 struct signal_struct *signal = p->signal;
879 struct task_struct *t;
880
881 /*
882 * Now find a thread we can wake up to take the signal off the queue.
883 *
884 * If the main thread wants the signal, it gets first crack.
885 * Probably the least surprising to the average bear.
886 */
887 if (wants_signal(sig, p))
888 t = p;
889 else if (!group || thread_group_empty(p))
890 /*
891 * There is just one thread and it does not need to be woken.
892 * It will dequeue unblocked signals before it runs again.
893 */
894 return;
895 else {
896 /*
897 * Otherwise try to find a suitable thread.
898 */
899 t = signal->curr_target;
900 while (!wants_signal(sig, t)) {
901 t = next_thread(t);
902 if (t == signal->curr_target)
903 /*
904 * No thread needs to be woken.
905 * Any eligible threads will see
906 * the signal in the queue soon.
907 */
908 return;
909 }
910 signal->curr_target = t;
911 }
912
913 /*
914 * Found a killable thread. If the signal will be fatal,
915 * then start taking the whole group down immediately.
916 */
917 if (sig_fatal(p, sig) &&
918 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
919 !sigismember(&t->real_blocked, sig) &&
920 (sig == SIGKILL || !t->ptrace)) {
921 /*
922 * This signal will be fatal to the whole group.
923 */
924 if (!sig_kernel_coredump(sig)) {
925 /*
926 * Start a group exit and wake everybody up.
927 * This way we don't have other threads
928 * running and doing things after a slower
929 * thread has the fatal signal pending.
930 */
931 signal->flags = SIGNAL_GROUP_EXIT;
932 signal->group_exit_code = sig;
933 signal->group_stop_count = 0;
934 t = p;
935 do {
936 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
937 sigaddset(&t->pending.signal, SIGKILL);
938 signal_wake_up(t, 1);
939 } while_each_thread(p, t);
940 return;
941 }
942 }
943
944 /*
945 * The signal is already in the shared-pending queue.
946 * Tell the chosen thread to wake up and dequeue it.
947 */
948 signal_wake_up(t, sig == SIGKILL);
949 return;
950}
951
952static inline int legacy_queue(struct sigpending *signals, int sig)
953{
954 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
955}
956
957#ifdef CONFIG_USER_NS
958static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
959{
960 if (current_user_ns() == task_cred_xxx(t, user_ns))
961 return;
962
963 if (SI_FROMKERNEL(info))
964 return;
965
966 rcu_read_lock();
967 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
968 make_kuid(current_user_ns(), info->si_uid));
969 rcu_read_unlock();
970}
971#else
972static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
973{
974 return;
975}
976#endif
977
978static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
979 int group, int from_ancestor_ns)
980{
981 struct sigpending *pending;
982 struct sigqueue *q;
983 int override_rlimit;
984 int ret = 0, result;
985
986 assert_spin_locked(&t->sighand->siglock);
987
988 result = TRACE_SIGNAL_IGNORED;
989 if (!prepare_signal(sig, t,
990 from_ancestor_ns || (info == SEND_SIG_FORCED)))
991 goto ret;
992
993 pending = group ? &t->signal->shared_pending : &t->pending;
994 /*
995 * Short-circuit ignored signals and support queuing
996 * exactly one non-rt signal, so that we can get more
997 * detailed information about the cause of the signal.
998 */
999 result = TRACE_SIGNAL_ALREADY_PENDING;
1000 if (legacy_queue(pending, sig))
1001 goto ret;
1002
1003 result = TRACE_SIGNAL_DELIVERED;
1004 /*
1005 * fast-pathed signals for kernel-internal things like SIGSTOP
1006 * or SIGKILL.
1007 */
1008 if (info == SEND_SIG_FORCED)
1009 goto out_set;
1010
1011 /*
1012 * Real-time signals must be queued if sent by sigqueue, or
1013 * some other real-time mechanism. It is implementation
1014 * defined whether kill() does so. We attempt to do so, on
1015 * the principle of least surprise, but since kill is not
1016 * allowed to fail with EAGAIN when low on memory we just
1017 * make sure at least one signal gets delivered and don't
1018 * pass on the info struct.
1019 */
1020 if (sig < SIGRTMIN)
1021 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1022 else
1023 override_rlimit = 0;
1024
1025 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1026 override_rlimit);
1027 if (q) {
1028 list_add_tail(&q->list, &pending->list);
1029 switch ((unsigned long) info) {
1030 case (unsigned long) SEND_SIG_NOINFO:
1031 q->info.si_signo = sig;
1032 q->info.si_errno = 0;
1033 q->info.si_code = SI_USER;
1034 q->info.si_pid = task_tgid_nr_ns(current,
1035 task_active_pid_ns(t));
1036 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1037 break;
1038 case (unsigned long) SEND_SIG_PRIV:
1039 q->info.si_signo = sig;
1040 q->info.si_errno = 0;
1041 q->info.si_code = SI_KERNEL;
1042 q->info.si_pid = 0;
1043 q->info.si_uid = 0;
1044 break;
1045 default:
1046 copy_siginfo(&q->info, info);
1047 if (from_ancestor_ns)
1048 q->info.si_pid = 0;
1049 break;
1050 }
1051
1052 userns_fixup_signal_uid(&q->info, t);
1053
1054 } else if (!is_si_special(info)) {
1055 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1056 /*
1057 * Queue overflow, abort. We may abort if the
1058 * signal was rt and sent by user using something
1059 * other than kill().
1060 */
1061 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1062 ret = -EAGAIN;
1063 goto ret;
1064 } else {
1065 /*
1066 * This is a silent loss of information. We still
1067 * send the signal, but the *info bits are lost.
1068 */
1069 result = TRACE_SIGNAL_LOSE_INFO;
1070 }
1071 }
1072
1073out_set:
1074 signalfd_notify(t, sig);
1075 sigaddset(&pending->signal, sig);
1076 complete_signal(sig, t, group);
1077ret:
1078 trace_signal_generate(sig, info, t, group, result);
1079 return ret;
1080}
1081
1082static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1083 int group)
1084{
1085 int from_ancestor_ns = 0;
1086
1087#ifdef CONFIG_PID_NS
1088 from_ancestor_ns = si_fromuser(info) &&
1089 !task_pid_nr_ns(current, task_active_pid_ns(t));
1090#endif
1091
1092 return __send_signal(sig, info, t, group, from_ancestor_ns);
1093}
1094
1095static void print_fatal_signal(int signr)
1096{
1097 struct pt_regs *regs = signal_pt_regs();
1098 pr_info("potentially unexpected fatal signal %d.\n", signr);
1099
1100#if defined(__i386__) && !defined(__arch_um__)
1101 pr_info("code at %08lx: ", regs->ip);
1102 {
1103 int i;
1104 for (i = 0; i < 16; i++) {
1105 unsigned char insn;
1106
1107 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1108 break;
1109 pr_cont("%02x ", insn);
1110 }
1111 }
1112 pr_cont("\n");
1113#endif
1114 preempt_disable();
1115 show_regs(regs);
1116 preempt_enable();
1117}
1118
1119static int __init setup_print_fatal_signals(char *str)
1120{
1121 get_option (&str, &print_fatal_signals);
1122
1123 return 1;
1124}
1125
1126__setup("print-fatal-signals=", setup_print_fatal_signals);
1127
1128int
1129__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1130{
1131 return send_signal(sig, info, p, 1);
1132}
1133
1134static int
1135specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1136{
1137 return send_signal(sig, info, t, 0);
1138}
1139
1140int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1141 bool group)
1142{
1143 unsigned long flags;
1144 int ret = -ESRCH;
1145
1146 if (lock_task_sighand(p, &flags)) {
1147 ret = send_signal(sig, info, p, group);
1148 unlock_task_sighand(p, &flags);
1149 }
1150
1151 return ret;
1152}
1153
1154/*
1155 * Force a signal that the process can't ignore: if necessary
1156 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1157 *
1158 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1159 * since we do not want to have a signal handler that was blocked
1160 * be invoked when user space had explicitly blocked it.
1161 *
1162 * We don't want to have recursive SIGSEGV's etc, for example,
1163 * that is why we also clear SIGNAL_UNKILLABLE.
1164 */
1165int
1166force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1167{
1168 unsigned long int flags;
1169 int ret, blocked, ignored;
1170 struct k_sigaction *action;
1171
1172 spin_lock_irqsave(&t->sighand->siglock, flags);
1173 action = &t->sighand->action[sig-1];
1174 ignored = action->sa.sa_handler == SIG_IGN;
1175 blocked = sigismember(&t->blocked, sig);
1176 if (blocked || ignored) {
1177 action->sa.sa_handler = SIG_DFL;
1178 if (blocked) {
1179 sigdelset(&t->blocked, sig);
1180 recalc_sigpending_and_wake(t);
1181 }
1182 }
1183 if (action->sa.sa_handler == SIG_DFL)
1184 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1185 ret = specific_send_sig_info(sig, info, t);
1186 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1187
1188 return ret;
1189}
1190
1191/*
1192 * Nuke all other threads in the group.
1193 */
1194int zap_other_threads(struct task_struct *p)
1195{
1196 struct task_struct *t = p;
1197 int count = 0;
1198
1199 p->signal->group_stop_count = 0;
1200
1201 while_each_thread(p, t) {
1202 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1203 count++;
1204
1205 /* Don't bother with already dead threads */
1206 if (t->exit_state)
1207 continue;
1208 sigaddset(&t->pending.signal, SIGKILL);
1209 signal_wake_up(t, 1);
1210 }
1211
1212 return count;
1213}
1214
1215struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1216 unsigned long *flags)
1217{
1218 struct sighand_struct *sighand;
1219
1220 for (;;) {
1221 /*
1222 * Disable interrupts early to avoid deadlocks.
1223 * See rcu_read_unlock() comment header for details.
1224 */
1225 local_irq_save(*flags);
1226 rcu_read_lock();
1227 sighand = rcu_dereference(tsk->sighand);
1228 if (unlikely(sighand == NULL)) {
1229 rcu_read_unlock();
1230 local_irq_restore(*flags);
1231 break;
1232 }
1233 /*
1234 * This sighand can be already freed and even reused, but
1235 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1236 * initializes ->siglock: this slab can't go away, it has
1237 * the same object type, ->siglock can't be reinitialized.
1238 *
1239 * We need to ensure that tsk->sighand is still the same
1240 * after we take the lock, we can race with de_thread() or
1241 * __exit_signal(). In the latter case the next iteration
1242 * must see ->sighand == NULL.
1243 */
1244 spin_lock(&sighand->siglock);
1245 if (likely(sighand == tsk->sighand)) {
1246 rcu_read_unlock();
1247 break;
1248 }
1249 spin_unlock(&sighand->siglock);
1250 rcu_read_unlock();
1251 local_irq_restore(*flags);
1252 }
1253
1254 return sighand;
1255}
1256
1257/*
1258 * send signal info to all the members of a group
1259 */
1260int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1261{
1262 int ret;
1263
1264 rcu_read_lock();
1265 ret = check_kill_permission(sig, info, p);
1266 rcu_read_unlock();
1267
1268 if (!ret && sig)
1269 ret = do_send_sig_info(sig, info, p, true);
1270
1271 return ret;
1272}
1273
1274/*
1275 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1276 * control characters do (^C, ^Z etc)
1277 * - the caller must hold at least a readlock on tasklist_lock
1278 */
1279int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1280{
1281 struct task_struct *p = NULL;
1282 int retval, success;
1283
1284 success = 0;
1285 retval = -ESRCH;
1286 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1287 int err = group_send_sig_info(sig, info, p);
1288 success |= !err;
1289 retval = err;
1290 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1291 return success ? 0 : retval;
1292}
1293
1294int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1295{
1296 int error = -ESRCH;
1297 struct task_struct *p;
1298
1299 for (;;) {
1300 rcu_read_lock();
1301 p = pid_task(pid, PIDTYPE_PID);
1302 if (p)
1303 error = group_send_sig_info(sig, info, p);
1304 rcu_read_unlock();
1305 if (likely(!p || error != -ESRCH))
1306 return error;
1307
1308 /*
1309 * The task was unhashed in between, try again. If it
1310 * is dead, pid_task() will return NULL, if we race with
1311 * de_thread() it will find the new leader.
1312 */
1313 }
1314}
1315
1316int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1317{
1318 int error;
1319 rcu_read_lock();
1320 error = kill_pid_info(sig, info, find_vpid(pid));
1321 rcu_read_unlock();
1322 return error;
1323}
1324
1325static int kill_as_cred_perm(const struct cred *cred,
1326 struct task_struct *target)
1327{
1328 const struct cred *pcred = __task_cred(target);
1329 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1330 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1331 return 0;
1332 return 1;
1333}
1334
1335/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1336int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1337 const struct cred *cred, u32 secid)
1338{
1339 int ret = -EINVAL;
1340 struct task_struct *p;
1341 unsigned long flags;
1342
1343 if (!valid_signal(sig))
1344 return ret;
1345
1346 rcu_read_lock();
1347 p = pid_task(pid, PIDTYPE_PID);
1348 if (!p) {
1349 ret = -ESRCH;
1350 goto out_unlock;
1351 }
1352 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1353 ret = -EPERM;
1354 goto out_unlock;
1355 }
1356 ret = security_task_kill(p, info, sig, secid);
1357 if (ret)
1358 goto out_unlock;
1359
1360 if (sig) {
1361 if (lock_task_sighand(p, &flags)) {
1362 ret = __send_signal(sig, info, p, 1, 0);
1363 unlock_task_sighand(p, &flags);
1364 } else
1365 ret = -ESRCH;
1366 }
1367out_unlock:
1368 rcu_read_unlock();
1369 return ret;
1370}
1371EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1372
1373/*
1374 * kill_something_info() interprets pid in interesting ways just like kill(2).
1375 *
1376 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1377 * is probably wrong. Should make it like BSD or SYSV.
1378 */
1379
1380static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1381{
1382 int ret;
1383
1384 if (pid > 0) {
1385 rcu_read_lock();
1386 ret = kill_pid_info(sig, info, find_vpid(pid));
1387 rcu_read_unlock();
1388 return ret;
1389 }
1390
1391 read_lock(&tasklist_lock);
1392 if (pid != -1) {
1393 ret = __kill_pgrp_info(sig, info,
1394 pid ? find_vpid(-pid) : task_pgrp(current));
1395 } else {
1396 int retval = 0, count = 0;
1397 struct task_struct * p;
1398
1399 for_each_process(p) {
1400 if (task_pid_vnr(p) > 1 &&
1401 !same_thread_group(p, current)) {
1402 int err = group_send_sig_info(sig, info, p);
1403 ++count;
1404 if (err != -EPERM)
1405 retval = err;
1406 }
1407 }
1408 ret = count ? retval : -ESRCH;
1409 }
1410 read_unlock(&tasklist_lock);
1411
1412 return ret;
1413}
1414
1415/*
1416 * These are for backward compatibility with the rest of the kernel source.
1417 */
1418
1419int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1420{
1421 /*
1422 * Make sure legacy kernel users don't send in bad values
1423 * (normal paths check this in check_kill_permission).
1424 */
1425 if (!valid_signal(sig))
1426 return -EINVAL;
1427
1428 return do_send_sig_info(sig, info, p, false);
1429}
1430
1431#define __si_special(priv) \
1432 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1433
1434int
1435send_sig(int sig, struct task_struct *p, int priv)
1436{
1437 return send_sig_info(sig, __si_special(priv), p);
1438}
1439
1440void
1441force_sig(int sig, struct task_struct *p)
1442{
1443 force_sig_info(sig, SEND_SIG_PRIV, p);
1444}
1445
1446/*
1447 * When things go south during signal handling, we
1448 * will force a SIGSEGV. And if the signal that caused
1449 * the problem was already a SIGSEGV, we'll want to
1450 * make sure we don't even try to deliver the signal..
1451 */
1452int
1453force_sigsegv(int sig, struct task_struct *p)
1454{
1455 if (sig == SIGSEGV) {
1456 unsigned long flags;
1457 spin_lock_irqsave(&p->sighand->siglock, flags);
1458 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1459 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1460 }
1461 force_sig(SIGSEGV, p);
1462 return 0;
1463}
1464
1465int kill_pgrp(struct pid *pid, int sig, int priv)
1466{
1467 int ret;
1468
1469 read_lock(&tasklist_lock);
1470 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1471 read_unlock(&tasklist_lock);
1472
1473 return ret;
1474}
1475EXPORT_SYMBOL(kill_pgrp);
1476
1477int kill_pid(struct pid *pid, int sig, int priv)
1478{
1479 return kill_pid_info(sig, __si_special(priv), pid);
1480}
1481EXPORT_SYMBOL(kill_pid);
1482
1483/*
1484 * These functions support sending signals using preallocated sigqueue
1485 * structures. This is needed "because realtime applications cannot
1486 * afford to lose notifications of asynchronous events, like timer
1487 * expirations or I/O completions". In the case of POSIX Timers
1488 * we allocate the sigqueue structure from the timer_create. If this
1489 * allocation fails we are able to report the failure to the application
1490 * with an EAGAIN error.
1491 */
1492struct sigqueue *sigqueue_alloc(void)
1493{
1494 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1495
1496 if (q)
1497 q->flags |= SIGQUEUE_PREALLOC;
1498
1499 return q;
1500}
1501
1502void sigqueue_free(struct sigqueue *q)
1503{
1504 unsigned long flags;
1505 spinlock_t *lock = ¤t->sighand->siglock;
1506
1507 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1508 /*
1509 * We must hold ->siglock while testing q->list
1510 * to serialize with collect_signal() or with
1511 * __exit_signal()->flush_sigqueue().
1512 */
1513 spin_lock_irqsave(lock, flags);
1514 q->flags &= ~SIGQUEUE_PREALLOC;
1515 /*
1516 * If it is queued it will be freed when dequeued,
1517 * like the "regular" sigqueue.
1518 */
1519 if (!list_empty(&q->list))
1520 q = NULL;
1521 spin_unlock_irqrestore(lock, flags);
1522
1523 if (q)
1524 __sigqueue_free(q);
1525}
1526
1527int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1528{
1529 int sig = q->info.si_signo;
1530 struct sigpending *pending;
1531 unsigned long flags;
1532 int ret, result;
1533
1534 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1535
1536 ret = -1;
1537 if (!likely(lock_task_sighand(t, &flags)))
1538 goto ret;
1539
1540 ret = 1; /* the signal is ignored */
1541 result = TRACE_SIGNAL_IGNORED;
1542 if (!prepare_signal(sig, t, false))
1543 goto out;
1544
1545 ret = 0;
1546 if (unlikely(!list_empty(&q->list))) {
1547 /*
1548 * If an SI_TIMER entry is already queue just increment
1549 * the overrun count.
1550 */
1551 BUG_ON(q->info.si_code != SI_TIMER);
1552 q->info.si_overrun++;
1553 result = TRACE_SIGNAL_ALREADY_PENDING;
1554 goto out;
1555 }
1556 q->info.si_overrun = 0;
1557
1558 signalfd_notify(t, sig);
1559 pending = group ? &t->signal->shared_pending : &t->pending;
1560 list_add_tail(&q->list, &pending->list);
1561 sigaddset(&pending->signal, sig);
1562 complete_signal(sig, t, group);
1563 result = TRACE_SIGNAL_DELIVERED;
1564out:
1565 trace_signal_generate(sig, &q->info, t, group, result);
1566 unlock_task_sighand(t, &flags);
1567ret:
1568 return ret;
1569}
1570
1571/*
1572 * Let a parent know about the death of a child.
1573 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1574 *
1575 * Returns true if our parent ignored us and so we've switched to
1576 * self-reaping.
1577 */
1578bool do_notify_parent(struct task_struct *tsk, int sig)
1579{
1580 struct siginfo info;
1581 unsigned long flags;
1582 struct sighand_struct *psig;
1583 bool autoreap = false;
1584 cputime_t utime, stime;
1585
1586 BUG_ON(sig == -1);
1587
1588 /* do_notify_parent_cldstop should have been called instead. */
1589 BUG_ON(task_is_stopped_or_traced(tsk));
1590
1591 BUG_ON(!tsk->ptrace &&
1592 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1593
1594 if (sig != SIGCHLD) {
1595 /*
1596 * This is only possible if parent == real_parent.
1597 * Check if it has changed security domain.
1598 */
1599 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1600 sig = SIGCHLD;
1601 }
1602
1603 info.si_signo = sig;
1604 info.si_errno = 0;
1605 /*
1606 * We are under tasklist_lock here so our parent is tied to
1607 * us and cannot change.
1608 *
1609 * task_active_pid_ns will always return the same pid namespace
1610 * until a task passes through release_task.
1611 *
1612 * write_lock() currently calls preempt_disable() which is the
1613 * same as rcu_read_lock(), but according to Oleg, this is not
1614 * correct to rely on this
1615 */
1616 rcu_read_lock();
1617 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1618 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1619 task_uid(tsk));
1620 rcu_read_unlock();
1621
1622 task_cputime(tsk, &utime, &stime);
1623 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1624 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1625
1626 info.si_status = tsk->exit_code & 0x7f;
1627 if (tsk->exit_code & 0x80)
1628 info.si_code = CLD_DUMPED;
1629 else if (tsk->exit_code & 0x7f)
1630 info.si_code = CLD_KILLED;
1631 else {
1632 info.si_code = CLD_EXITED;
1633 info.si_status = tsk->exit_code >> 8;
1634 }
1635
1636 psig = tsk->parent->sighand;
1637 spin_lock_irqsave(&psig->siglock, flags);
1638 if (!tsk->ptrace && sig == SIGCHLD &&
1639 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1640 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1641 /*
1642 * We are exiting and our parent doesn't care. POSIX.1
1643 * defines special semantics for setting SIGCHLD to SIG_IGN
1644 * or setting the SA_NOCLDWAIT flag: we should be reaped
1645 * automatically and not left for our parent's wait4 call.
1646 * Rather than having the parent do it as a magic kind of
1647 * signal handler, we just set this to tell do_exit that we
1648 * can be cleaned up without becoming a zombie. Note that
1649 * we still call __wake_up_parent in this case, because a
1650 * blocked sys_wait4 might now return -ECHILD.
1651 *
1652 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1653 * is implementation-defined: we do (if you don't want
1654 * it, just use SIG_IGN instead).
1655 */
1656 autoreap = true;
1657 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1658 sig = 0;
1659 }
1660 if (valid_signal(sig) && sig)
1661 __group_send_sig_info(sig, &info, tsk->parent);
1662 __wake_up_parent(tsk, tsk->parent);
1663 spin_unlock_irqrestore(&psig->siglock, flags);
1664
1665 return autoreap;
1666}
1667
1668/**
1669 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1670 * @tsk: task reporting the state change
1671 * @for_ptracer: the notification is for ptracer
1672 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1673 *
1674 * Notify @tsk's parent that the stopped/continued state has changed. If
1675 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1676 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1677 *
1678 * CONTEXT:
1679 * Must be called with tasklist_lock at least read locked.
1680 */
1681static void do_notify_parent_cldstop(struct task_struct *tsk,
1682 bool for_ptracer, int why)
1683{
1684 struct siginfo info;
1685 unsigned long flags;
1686 struct task_struct *parent;
1687 struct sighand_struct *sighand;
1688 cputime_t utime, stime;
1689
1690 if (for_ptracer) {
1691 parent = tsk->parent;
1692 } else {
1693 tsk = tsk->group_leader;
1694 parent = tsk->real_parent;
1695 }
1696
1697 info.si_signo = SIGCHLD;
1698 info.si_errno = 0;
1699 /*
1700 * see comment in do_notify_parent() about the following 4 lines
1701 */
1702 rcu_read_lock();
1703 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1704 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1705 rcu_read_unlock();
1706
1707 task_cputime(tsk, &utime, &stime);
1708 info.si_utime = cputime_to_clock_t(utime);
1709 info.si_stime = cputime_to_clock_t(stime);
1710
1711 info.si_code = why;
1712 switch (why) {
1713 case CLD_CONTINUED:
1714 info.si_status = SIGCONT;
1715 break;
1716 case CLD_STOPPED:
1717 info.si_status = tsk->signal->group_exit_code & 0x7f;
1718 break;
1719 case CLD_TRAPPED:
1720 info.si_status = tsk->exit_code & 0x7f;
1721 break;
1722 default:
1723 BUG();
1724 }
1725
1726 sighand = parent->sighand;
1727 spin_lock_irqsave(&sighand->siglock, flags);
1728 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1729 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1730 __group_send_sig_info(SIGCHLD, &info, parent);
1731 /*
1732 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1733 */
1734 __wake_up_parent(tsk, parent);
1735 spin_unlock_irqrestore(&sighand->siglock, flags);
1736}
1737
1738static inline int may_ptrace_stop(void)
1739{
1740 if (!likely(current->ptrace))
1741 return 0;
1742 /*
1743 * Are we in the middle of do_coredump?
1744 * If so and our tracer is also part of the coredump stopping
1745 * is a deadlock situation, and pointless because our tracer
1746 * is dead so don't allow us to stop.
1747 * If SIGKILL was already sent before the caller unlocked
1748 * ->siglock we must see ->core_state != NULL. Otherwise it
1749 * is safe to enter schedule().
1750 *
1751 * This is almost outdated, a task with the pending SIGKILL can't
1752 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1753 * after SIGKILL was already dequeued.
1754 */
1755 if (unlikely(current->mm->core_state) &&
1756 unlikely(current->mm == current->parent->mm))
1757 return 0;
1758
1759 return 1;
1760}
1761
1762/*
1763 * Return non-zero if there is a SIGKILL that should be waking us up.
1764 * Called with the siglock held.
1765 */
1766static int sigkill_pending(struct task_struct *tsk)
1767{
1768 return sigismember(&tsk->pending.signal, SIGKILL) ||
1769 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1770}
1771
1772/*
1773 * This must be called with current->sighand->siglock held.
1774 *
1775 * This should be the path for all ptrace stops.
1776 * We always set current->last_siginfo while stopped here.
1777 * That makes it a way to test a stopped process for
1778 * being ptrace-stopped vs being job-control-stopped.
1779 *
1780 * If we actually decide not to stop at all because the tracer
1781 * is gone, we keep current->exit_code unless clear_code.
1782 */
1783static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1784 __releases(¤t->sighand->siglock)
1785 __acquires(¤t->sighand->siglock)
1786{
1787 bool gstop_done = false;
1788
1789 if (arch_ptrace_stop_needed(exit_code, info)) {
1790 /*
1791 * The arch code has something special to do before a
1792 * ptrace stop. This is allowed to block, e.g. for faults
1793 * on user stack pages. We can't keep the siglock while
1794 * calling arch_ptrace_stop, so we must release it now.
1795 * To preserve proper semantics, we must do this before
1796 * any signal bookkeeping like checking group_stop_count.
1797 * Meanwhile, a SIGKILL could come in before we retake the
1798 * siglock. That must prevent us from sleeping in TASK_TRACED.
1799 * So after regaining the lock, we must check for SIGKILL.
1800 */
1801 spin_unlock_irq(¤t->sighand->siglock);
1802 arch_ptrace_stop(exit_code, info);
1803 spin_lock_irq(¤t->sighand->siglock);
1804 if (sigkill_pending(current))
1805 return;
1806 }
1807
1808 /*
1809 * We're committing to trapping. TRACED should be visible before
1810 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1811 * Also, transition to TRACED and updates to ->jobctl should be
1812 * atomic with respect to siglock and should be done after the arch
1813 * hook as siglock is released and regrabbed across it.
1814 */
1815 set_current_state(TASK_TRACED);
1816
1817 current->last_siginfo = info;
1818 current->exit_code = exit_code;
1819
1820 /*
1821 * If @why is CLD_STOPPED, we're trapping to participate in a group
1822 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1823 * across siglock relocks since INTERRUPT was scheduled, PENDING
1824 * could be clear now. We act as if SIGCONT is received after
1825 * TASK_TRACED is entered - ignore it.
1826 */
1827 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1828 gstop_done = task_participate_group_stop(current);
1829
1830 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1831 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1832 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1833 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1834
1835 /* entering a trap, clear TRAPPING */
1836 task_clear_jobctl_trapping(current);
1837
1838 spin_unlock_irq(¤t->sighand->siglock);
1839 read_lock(&tasklist_lock);
1840 if (may_ptrace_stop()) {
1841 /*
1842 * Notify parents of the stop.
1843 *
1844 * While ptraced, there are two parents - the ptracer and
1845 * the real_parent of the group_leader. The ptracer should
1846 * know about every stop while the real parent is only
1847 * interested in the completion of group stop. The states
1848 * for the two don't interact with each other. Notify
1849 * separately unless they're gonna be duplicates.
1850 */
1851 do_notify_parent_cldstop(current, true, why);
1852 if (gstop_done && ptrace_reparented(current))
1853 do_notify_parent_cldstop(current, false, why);
1854
1855 /*
1856 * Don't want to allow preemption here, because
1857 * sys_ptrace() needs this task to be inactive.
1858 *
1859 * XXX: implement read_unlock_no_resched().
1860 */
1861 preempt_disable();
1862 read_unlock(&tasklist_lock);
1863 preempt_enable_no_resched();
1864 freezable_schedule();
1865 } else {
1866 /*
1867 * By the time we got the lock, our tracer went away.
1868 * Don't drop the lock yet, another tracer may come.
1869 *
1870 * If @gstop_done, the ptracer went away between group stop
1871 * completion and here. During detach, it would have set
1872 * JOBCTL_STOP_PENDING on us and we'll re-enter
1873 * TASK_STOPPED in do_signal_stop() on return, so notifying
1874 * the real parent of the group stop completion is enough.
1875 */
1876 if (gstop_done)
1877 do_notify_parent_cldstop(current, false, why);
1878
1879 /* tasklist protects us from ptrace_freeze_traced() */
1880 __set_current_state(TASK_RUNNING);
1881 if (clear_code)
1882 current->exit_code = 0;
1883 read_unlock(&tasklist_lock);
1884 }
1885
1886 /*
1887 * We are back. Now reacquire the siglock before touching
1888 * last_siginfo, so that we are sure to have synchronized with
1889 * any signal-sending on another CPU that wants to examine it.
1890 */
1891 spin_lock_irq(¤t->sighand->siglock);
1892 current->last_siginfo = NULL;
1893
1894 /* LISTENING can be set only during STOP traps, clear it */
1895 current->jobctl &= ~JOBCTL_LISTENING;
1896
1897 /*
1898 * Queued signals ignored us while we were stopped for tracing.
1899 * So check for any that we should take before resuming user mode.
1900 * This sets TIF_SIGPENDING, but never clears it.
1901 */
1902 recalc_sigpending_tsk(current);
1903}
1904
1905static void ptrace_do_notify(int signr, int exit_code, int why)
1906{
1907 siginfo_t info;
1908
1909 memset(&info, 0, sizeof info);
1910 info.si_signo = signr;
1911 info.si_code = exit_code;
1912 info.si_pid = task_pid_vnr(current);
1913 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1914
1915 /* Let the debugger run. */
1916 ptrace_stop(exit_code, why, 1, &info);
1917}
1918
1919void ptrace_notify(int exit_code)
1920{
1921 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1922 if (unlikely(current->task_works))
1923 task_work_run();
1924
1925 spin_lock_irq(¤t->sighand->siglock);
1926 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1927 spin_unlock_irq(¤t->sighand->siglock);
1928}
1929
1930/**
1931 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1932 * @signr: signr causing group stop if initiating
1933 *
1934 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1935 * and participate in it. If already set, participate in the existing
1936 * group stop. If participated in a group stop (and thus slept), %true is
1937 * returned with siglock released.
1938 *
1939 * If ptraced, this function doesn't handle stop itself. Instead,
1940 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1941 * untouched. The caller must ensure that INTERRUPT trap handling takes
1942 * places afterwards.
1943 *
1944 * CONTEXT:
1945 * Must be called with @current->sighand->siglock held, which is released
1946 * on %true return.
1947 *
1948 * RETURNS:
1949 * %false if group stop is already cancelled or ptrace trap is scheduled.
1950 * %true if participated in group stop.
1951 */
1952static bool do_signal_stop(int signr)
1953 __releases(¤t->sighand->siglock)
1954{
1955 struct signal_struct *sig = current->signal;
1956
1957 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1958 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1959 struct task_struct *t;
1960
1961 /* signr will be recorded in task->jobctl for retries */
1962 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1963
1964 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1965 unlikely(signal_group_exit(sig)))
1966 return false;
1967 /*
1968 * There is no group stop already in progress. We must
1969 * initiate one now.
1970 *
1971 * While ptraced, a task may be resumed while group stop is
1972 * still in effect and then receive a stop signal and
1973 * initiate another group stop. This deviates from the
1974 * usual behavior as two consecutive stop signals can't
1975 * cause two group stops when !ptraced. That is why we
1976 * also check !task_is_stopped(t) below.
1977 *
1978 * The condition can be distinguished by testing whether
1979 * SIGNAL_STOP_STOPPED is already set. Don't generate
1980 * group_exit_code in such case.
1981 *
1982 * This is not necessary for SIGNAL_STOP_CONTINUED because
1983 * an intervening stop signal is required to cause two
1984 * continued events regardless of ptrace.
1985 */
1986 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1987 sig->group_exit_code = signr;
1988
1989 sig->group_stop_count = 0;
1990
1991 if (task_set_jobctl_pending(current, signr | gstop))
1992 sig->group_stop_count++;
1993
1994 t = current;
1995 while_each_thread(current, t) {
1996 /*
1997 * Setting state to TASK_STOPPED for a group
1998 * stop is always done with the siglock held,
1999 * so this check has no races.
2000 */
2001 if (!task_is_stopped(t) &&
2002 task_set_jobctl_pending(t, signr | gstop)) {
2003 sig->group_stop_count++;
2004 if (likely(!(t->ptrace & PT_SEIZED)))
2005 signal_wake_up(t, 0);
2006 else
2007 ptrace_trap_notify(t);
2008 }
2009 }
2010 }
2011
2012 if (likely(!current->ptrace)) {
2013 int notify = 0;
2014
2015 /*
2016 * If there are no other threads in the group, or if there
2017 * is a group stop in progress and we are the last to stop,
2018 * report to the parent.
2019 */
2020 if (task_participate_group_stop(current))
2021 notify = CLD_STOPPED;
2022
2023 __set_current_state(TASK_STOPPED);
2024 spin_unlock_irq(¤t->sighand->siglock);
2025
2026 /*
2027 * Notify the parent of the group stop completion. Because
2028 * we're not holding either the siglock or tasklist_lock
2029 * here, ptracer may attach inbetween; however, this is for
2030 * group stop and should always be delivered to the real
2031 * parent of the group leader. The new ptracer will get
2032 * its notification when this task transitions into
2033 * TASK_TRACED.
2034 */
2035 if (notify) {
2036 read_lock(&tasklist_lock);
2037 do_notify_parent_cldstop(current, false, notify);
2038 read_unlock(&tasklist_lock);
2039 }
2040
2041 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2042 freezable_schedule();
2043 return true;
2044 } else {
2045 /*
2046 * While ptraced, group stop is handled by STOP trap.
2047 * Schedule it and let the caller deal with it.
2048 */
2049 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2050 return false;
2051 }
2052}
2053
2054/**
2055 * do_jobctl_trap - take care of ptrace jobctl traps
2056 *
2057 * When PT_SEIZED, it's used for both group stop and explicit
2058 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2059 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2060 * the stop signal; otherwise, %SIGTRAP.
2061 *
2062 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2063 * number as exit_code and no siginfo.
2064 *
2065 * CONTEXT:
2066 * Must be called with @current->sighand->siglock held, which may be
2067 * released and re-acquired before returning with intervening sleep.
2068 */
2069static void do_jobctl_trap(void)
2070{
2071 struct signal_struct *signal = current->signal;
2072 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2073
2074 if (current->ptrace & PT_SEIZED) {
2075 if (!signal->group_stop_count &&
2076 !(signal->flags & SIGNAL_STOP_STOPPED))
2077 signr = SIGTRAP;
2078 WARN_ON_ONCE(!signr);
2079 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2080 CLD_STOPPED);
2081 } else {
2082 WARN_ON_ONCE(!signr);
2083 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2084 current->exit_code = 0;
2085 }
2086}
2087
2088static int ptrace_signal(int signr, siginfo_t *info)
2089{
2090 ptrace_signal_deliver();
2091 /*
2092 * We do not check sig_kernel_stop(signr) but set this marker
2093 * unconditionally because we do not know whether debugger will
2094 * change signr. This flag has no meaning unless we are going
2095 * to stop after return from ptrace_stop(). In this case it will
2096 * be checked in do_signal_stop(), we should only stop if it was
2097 * not cleared by SIGCONT while we were sleeping. See also the
2098 * comment in dequeue_signal().
2099 */
2100 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2101 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2102
2103 /* We're back. Did the debugger cancel the sig? */
2104 signr = current->exit_code;
2105 if (signr == 0)
2106 return signr;
2107
2108 current->exit_code = 0;
2109
2110 /*
2111 * Update the siginfo structure if the signal has
2112 * changed. If the debugger wanted something
2113 * specific in the siginfo structure then it should
2114 * have updated *info via PTRACE_SETSIGINFO.
2115 */
2116 if (signr != info->si_signo) {
2117 info->si_signo = signr;
2118 info->si_errno = 0;
2119 info->si_code = SI_USER;
2120 rcu_read_lock();
2121 info->si_pid = task_pid_vnr(current->parent);
2122 info->si_uid = from_kuid_munged(current_user_ns(),
2123 task_uid(current->parent));
2124 rcu_read_unlock();
2125 }
2126
2127 /* If the (new) signal is now blocked, requeue it. */
2128 if (sigismember(¤t->blocked, signr)) {
2129 specific_send_sig_info(signr, info, current);
2130 signr = 0;
2131 }
2132
2133 return signr;
2134}
2135
2136int get_signal(struct ksignal *ksig)
2137{
2138 struct sighand_struct *sighand = current->sighand;
2139 struct signal_struct *signal = current->signal;
2140 int signr;
2141
2142 if (unlikely(current->task_works))
2143 task_work_run();
2144
2145 if (unlikely(uprobe_deny_signal()))
2146 return 0;
2147
2148 /*
2149 * Do this once, we can't return to user-mode if freezing() == T.
2150 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2151 * thus do not need another check after return.
2152 */
2153 try_to_freeze();
2154
2155relock:
2156 spin_lock_irq(&sighand->siglock);
2157 /*
2158 * Every stopped thread goes here after wakeup. Check to see if
2159 * we should notify the parent, prepare_signal(SIGCONT) encodes
2160 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2161 */
2162 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2163 int why;
2164
2165 if (signal->flags & SIGNAL_CLD_CONTINUED)
2166 why = CLD_CONTINUED;
2167 else
2168 why = CLD_STOPPED;
2169
2170 signal->flags &= ~SIGNAL_CLD_MASK;
2171
2172 spin_unlock_irq(&sighand->siglock);
2173
2174 /*
2175 * Notify the parent that we're continuing. This event is
2176 * always per-process and doesn't make whole lot of sense
2177 * for ptracers, who shouldn't consume the state via
2178 * wait(2) either, but, for backward compatibility, notify
2179 * the ptracer of the group leader too unless it's gonna be
2180 * a duplicate.
2181 */
2182 read_lock(&tasklist_lock);
2183 do_notify_parent_cldstop(current, false, why);
2184
2185 if (ptrace_reparented(current->group_leader))
2186 do_notify_parent_cldstop(current->group_leader,
2187 true, why);
2188 read_unlock(&tasklist_lock);
2189
2190 goto relock;
2191 }
2192
2193 for (;;) {
2194 struct k_sigaction *ka;
2195
2196 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2197 do_signal_stop(0))
2198 goto relock;
2199
2200 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2201 do_jobctl_trap();
2202 spin_unlock_irq(&sighand->siglock);
2203 goto relock;
2204 }
2205
2206 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2207
2208 if (!signr)
2209 break; /* will return 0 */
2210
2211 if (unlikely(current->ptrace) && signr != SIGKILL) {
2212 signr = ptrace_signal(signr, &ksig->info);
2213 if (!signr)
2214 continue;
2215 }
2216
2217 ka = &sighand->action[signr-1];
2218
2219 /* Trace actually delivered signals. */
2220 trace_signal_deliver(signr, &ksig->info, ka);
2221
2222 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2223 continue;
2224 if (ka->sa.sa_handler != SIG_DFL) {
2225 /* Run the handler. */
2226 ksig->ka = *ka;
2227
2228 if (ka->sa.sa_flags & SA_ONESHOT)
2229 ka->sa.sa_handler = SIG_DFL;
2230
2231 break; /* will return non-zero "signr" value */
2232 }
2233
2234 /*
2235 * Now we are doing the default action for this signal.
2236 */
2237 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2238 continue;
2239
2240 /*
2241 * Global init gets no signals it doesn't want.
2242 * Container-init gets no signals it doesn't want from same
2243 * container.
2244 *
2245 * Note that if global/container-init sees a sig_kernel_only()
2246 * signal here, the signal must have been generated internally
2247 * or must have come from an ancestor namespace. In either
2248 * case, the signal cannot be dropped.
2249 */
2250 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2251 !sig_kernel_only(signr))
2252 continue;
2253
2254 if (sig_kernel_stop(signr)) {
2255 /*
2256 * The default action is to stop all threads in
2257 * the thread group. The job control signals
2258 * do nothing in an orphaned pgrp, but SIGSTOP
2259 * always works. Note that siglock needs to be
2260 * dropped during the call to is_orphaned_pgrp()
2261 * because of lock ordering with tasklist_lock.
2262 * This allows an intervening SIGCONT to be posted.
2263 * We need to check for that and bail out if necessary.
2264 */
2265 if (signr != SIGSTOP) {
2266 spin_unlock_irq(&sighand->siglock);
2267
2268 /* signals can be posted during this window */
2269
2270 if (is_current_pgrp_orphaned())
2271 goto relock;
2272
2273 spin_lock_irq(&sighand->siglock);
2274 }
2275
2276 if (likely(do_signal_stop(ksig->info.si_signo))) {
2277 /* It released the siglock. */
2278 goto relock;
2279 }
2280
2281 /*
2282 * We didn't actually stop, due to a race
2283 * with SIGCONT or something like that.
2284 */
2285 continue;
2286 }
2287
2288 spin_unlock_irq(&sighand->siglock);
2289
2290 /*
2291 * Anything else is fatal, maybe with a core dump.
2292 */
2293 current->flags |= PF_SIGNALED;
2294
2295 if (sig_kernel_coredump(signr)) {
2296 if (print_fatal_signals)
2297 print_fatal_signal(ksig->info.si_signo);
2298 proc_coredump_connector(current);
2299 /*
2300 * If it was able to dump core, this kills all
2301 * other threads in the group and synchronizes with
2302 * their demise. If we lost the race with another
2303 * thread getting here, it set group_exit_code
2304 * first and our do_group_exit call below will use
2305 * that value and ignore the one we pass it.
2306 */
2307 do_coredump(&ksig->info);
2308 }
2309
2310 /*
2311 * Death signals, no core dump.
2312 */
2313 do_group_exit(ksig->info.si_signo);
2314 /* NOTREACHED */
2315 }
2316 spin_unlock_irq(&sighand->siglock);
2317
2318 ksig->sig = signr;
2319 return ksig->sig > 0;
2320}
2321
2322/**
2323 * signal_delivered -
2324 * @ksig: kernel signal struct
2325 * @stepping: nonzero if debugger single-step or block-step in use
2326 *
2327 * This function should be called when a signal has successfully been
2328 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2329 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2330 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2331 */
2332static void signal_delivered(struct ksignal *ksig, int stepping)
2333{
2334 sigset_t blocked;
2335
2336 /* A signal was successfully delivered, and the
2337 saved sigmask was stored on the signal frame,
2338 and will be restored by sigreturn. So we can
2339 simply clear the restore sigmask flag. */
2340 clear_restore_sigmask();
2341
2342 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2343 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2344 sigaddset(&blocked, ksig->sig);
2345 set_current_blocked(&blocked);
2346 tracehook_signal_handler(stepping);
2347}
2348
2349void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2350{
2351 if (failed)
2352 force_sigsegv(ksig->sig, current);
2353 else
2354 signal_delivered(ksig, stepping);
2355}
2356
2357/*
2358 * It could be that complete_signal() picked us to notify about the
2359 * group-wide signal. Other threads should be notified now to take
2360 * the shared signals in @which since we will not.
2361 */
2362static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2363{
2364 sigset_t retarget;
2365 struct task_struct *t;
2366
2367 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2368 if (sigisemptyset(&retarget))
2369 return;
2370
2371 t = tsk;
2372 while_each_thread(tsk, t) {
2373 if (t->flags & PF_EXITING)
2374 continue;
2375
2376 if (!has_pending_signals(&retarget, &t->blocked))
2377 continue;
2378 /* Remove the signals this thread can handle. */
2379 sigandsets(&retarget, &retarget, &t->blocked);
2380
2381 if (!signal_pending(t))
2382 signal_wake_up(t, 0);
2383
2384 if (sigisemptyset(&retarget))
2385 break;
2386 }
2387}
2388
2389void exit_signals(struct task_struct *tsk)
2390{
2391 int group_stop = 0;
2392 sigset_t unblocked;
2393
2394 /*
2395 * @tsk is about to have PF_EXITING set - lock out users which
2396 * expect stable threadgroup.
2397 */
2398 threadgroup_change_begin(tsk);
2399
2400 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2401 tsk->flags |= PF_EXITING;
2402 threadgroup_change_end(tsk);
2403 return;
2404 }
2405
2406 spin_lock_irq(&tsk->sighand->siglock);
2407 /*
2408 * From now this task is not visible for group-wide signals,
2409 * see wants_signal(), do_signal_stop().
2410 */
2411 tsk->flags |= PF_EXITING;
2412
2413 threadgroup_change_end(tsk);
2414
2415 if (!signal_pending(tsk))
2416 goto out;
2417
2418 unblocked = tsk->blocked;
2419 signotset(&unblocked);
2420 retarget_shared_pending(tsk, &unblocked);
2421
2422 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2423 task_participate_group_stop(tsk))
2424 group_stop = CLD_STOPPED;
2425out:
2426 spin_unlock_irq(&tsk->sighand->siglock);
2427
2428 /*
2429 * If group stop has completed, deliver the notification. This
2430 * should always go to the real parent of the group leader.
2431 */
2432 if (unlikely(group_stop)) {
2433 read_lock(&tasklist_lock);
2434 do_notify_parent_cldstop(tsk, false, group_stop);
2435 read_unlock(&tasklist_lock);
2436 }
2437}
2438
2439EXPORT_SYMBOL(recalc_sigpending);
2440EXPORT_SYMBOL_GPL(dequeue_signal);
2441EXPORT_SYMBOL(flush_signals);
2442EXPORT_SYMBOL(force_sig);
2443EXPORT_SYMBOL(send_sig);
2444EXPORT_SYMBOL(send_sig_info);
2445EXPORT_SYMBOL(sigprocmask);
2446
2447/*
2448 * System call entry points.
2449 */
2450
2451/**
2452 * sys_restart_syscall - restart a system call
2453 */
2454SYSCALL_DEFINE0(restart_syscall)
2455{
2456 struct restart_block *restart = ¤t->restart_block;
2457 return restart->fn(restart);
2458}
2459
2460long do_no_restart_syscall(struct restart_block *param)
2461{
2462 return -EINTR;
2463}
2464
2465static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2466{
2467 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2468 sigset_t newblocked;
2469 /* A set of now blocked but previously unblocked signals. */
2470 sigandnsets(&newblocked, newset, ¤t->blocked);
2471 retarget_shared_pending(tsk, &newblocked);
2472 }
2473 tsk->blocked = *newset;
2474 recalc_sigpending();
2475}
2476
2477/**
2478 * set_current_blocked - change current->blocked mask
2479 * @newset: new mask
2480 *
2481 * It is wrong to change ->blocked directly, this helper should be used
2482 * to ensure the process can't miss a shared signal we are going to block.
2483 */
2484void set_current_blocked(sigset_t *newset)
2485{
2486 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2487 __set_current_blocked(newset);
2488}
2489
2490void __set_current_blocked(const sigset_t *newset)
2491{
2492 struct task_struct *tsk = current;
2493
2494 /*
2495 * In case the signal mask hasn't changed, there is nothing we need
2496 * to do. The current->blocked shouldn't be modified by other task.
2497 */
2498 if (sigequalsets(&tsk->blocked, newset))
2499 return;
2500
2501 spin_lock_irq(&tsk->sighand->siglock);
2502 __set_task_blocked(tsk, newset);
2503 spin_unlock_irq(&tsk->sighand->siglock);
2504}
2505
2506/*
2507 * This is also useful for kernel threads that want to temporarily
2508 * (or permanently) block certain signals.
2509 *
2510 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2511 * interface happily blocks "unblockable" signals like SIGKILL
2512 * and friends.
2513 */
2514int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2515{
2516 struct task_struct *tsk = current;
2517 sigset_t newset;
2518
2519 /* Lockless, only current can change ->blocked, never from irq */
2520 if (oldset)
2521 *oldset = tsk->blocked;
2522
2523 switch (how) {
2524 case SIG_BLOCK:
2525 sigorsets(&newset, &tsk->blocked, set);
2526 break;
2527 case SIG_UNBLOCK:
2528 sigandnsets(&newset, &tsk->blocked, set);
2529 break;
2530 case SIG_SETMASK:
2531 newset = *set;
2532 break;
2533 default:
2534 return -EINVAL;
2535 }
2536
2537 __set_current_blocked(&newset);
2538 return 0;
2539}
2540
2541/**
2542 * sys_rt_sigprocmask - change the list of currently blocked signals
2543 * @how: whether to add, remove, or set signals
2544 * @nset: stores pending signals
2545 * @oset: previous value of signal mask if non-null
2546 * @sigsetsize: size of sigset_t type
2547 */
2548SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2549 sigset_t __user *, oset, size_t, sigsetsize)
2550{
2551 sigset_t old_set, new_set;
2552 int error;
2553
2554 /* XXX: Don't preclude handling different sized sigset_t's. */
2555 if (sigsetsize != sizeof(sigset_t))
2556 return -EINVAL;
2557
2558 old_set = current->blocked;
2559
2560 if (nset) {
2561 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2562 return -EFAULT;
2563 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2564
2565 error = sigprocmask(how, &new_set, NULL);
2566 if (error)
2567 return error;
2568 }
2569
2570 if (oset) {
2571 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2572 return -EFAULT;
2573 }
2574
2575 return 0;
2576}
2577
2578#ifdef CONFIG_COMPAT
2579COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2580 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2581{
2582#ifdef __BIG_ENDIAN
2583 sigset_t old_set = current->blocked;
2584
2585 /* XXX: Don't preclude handling different sized sigset_t's. */
2586 if (sigsetsize != sizeof(sigset_t))
2587 return -EINVAL;
2588
2589 if (nset) {
2590 compat_sigset_t new32;
2591 sigset_t new_set;
2592 int error;
2593 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2594 return -EFAULT;
2595
2596 sigset_from_compat(&new_set, &new32);
2597 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2598
2599 error = sigprocmask(how, &new_set, NULL);
2600 if (error)
2601 return error;
2602 }
2603 if (oset) {
2604 compat_sigset_t old32;
2605 sigset_to_compat(&old32, &old_set);
2606 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2607 return -EFAULT;
2608 }
2609 return 0;
2610#else
2611 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2612 (sigset_t __user *)oset, sigsetsize);
2613#endif
2614}
2615#endif
2616
2617static int do_sigpending(void *set, unsigned long sigsetsize)
2618{
2619 if (sigsetsize > sizeof(sigset_t))
2620 return -EINVAL;
2621
2622 spin_lock_irq(¤t->sighand->siglock);
2623 sigorsets(set, ¤t->pending.signal,
2624 ¤t->signal->shared_pending.signal);
2625 spin_unlock_irq(¤t->sighand->siglock);
2626
2627 /* Outside the lock because only this thread touches it. */
2628 sigandsets(set, ¤t->blocked, set);
2629 return 0;
2630}
2631
2632/**
2633 * sys_rt_sigpending - examine a pending signal that has been raised
2634 * while blocked
2635 * @uset: stores pending signals
2636 * @sigsetsize: size of sigset_t type or larger
2637 */
2638SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2639{
2640 sigset_t set;
2641 int err = do_sigpending(&set, sigsetsize);
2642 if (!err && copy_to_user(uset, &set, sigsetsize))
2643 err = -EFAULT;
2644 return err;
2645}
2646
2647#ifdef CONFIG_COMPAT
2648COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2649 compat_size_t, sigsetsize)
2650{
2651#ifdef __BIG_ENDIAN
2652 sigset_t set;
2653 int err = do_sigpending(&set, sigsetsize);
2654 if (!err) {
2655 compat_sigset_t set32;
2656 sigset_to_compat(&set32, &set);
2657 /* we can get here only if sigsetsize <= sizeof(set) */
2658 if (copy_to_user(uset, &set32, sigsetsize))
2659 err = -EFAULT;
2660 }
2661 return err;
2662#else
2663 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2664#endif
2665}
2666#endif
2667
2668#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2669
2670int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2671{
2672 int err;
2673
2674 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2675 return -EFAULT;
2676 if (from->si_code < 0)
2677 return __copy_to_user(to, from, sizeof(siginfo_t))
2678 ? -EFAULT : 0;
2679 /*
2680 * If you change siginfo_t structure, please be sure
2681 * this code is fixed accordingly.
2682 * Please remember to update the signalfd_copyinfo() function
2683 * inside fs/signalfd.c too, in case siginfo_t changes.
2684 * It should never copy any pad contained in the structure
2685 * to avoid security leaks, but must copy the generic
2686 * 3 ints plus the relevant union member.
2687 */
2688 err = __put_user(from->si_signo, &to->si_signo);
2689 err |= __put_user(from->si_errno, &to->si_errno);
2690 err |= __put_user((short)from->si_code, &to->si_code);
2691 switch (from->si_code & __SI_MASK) {
2692 case __SI_KILL:
2693 err |= __put_user(from->si_pid, &to->si_pid);
2694 err |= __put_user(from->si_uid, &to->si_uid);
2695 break;
2696 case __SI_TIMER:
2697 err |= __put_user(from->si_tid, &to->si_tid);
2698 err |= __put_user(from->si_overrun, &to->si_overrun);
2699 err |= __put_user(from->si_ptr, &to->si_ptr);
2700 break;
2701 case __SI_POLL:
2702 err |= __put_user(from->si_band, &to->si_band);
2703 err |= __put_user(from->si_fd, &to->si_fd);
2704 break;
2705 case __SI_FAULT:
2706 err |= __put_user(from->si_addr, &to->si_addr);
2707#ifdef __ARCH_SI_TRAPNO
2708 err |= __put_user(from->si_trapno, &to->si_trapno);
2709#endif
2710#ifdef BUS_MCEERR_AO
2711 /*
2712 * Other callers might not initialize the si_lsb field,
2713 * so check explicitly for the right codes here.
2714 */
2715 if (from->si_signo == SIGBUS &&
2716 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2717 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2718#endif
2719#ifdef SEGV_BNDERR
2720 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2721 err |= __put_user(from->si_lower, &to->si_lower);
2722 err |= __put_user(from->si_upper, &to->si_upper);
2723 }
2724#endif
2725#ifdef SEGV_PKUERR
2726 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2727 err |= __put_user(from->si_pkey, &to->si_pkey);
2728#endif
2729 break;
2730 case __SI_CHLD:
2731 err |= __put_user(from->si_pid, &to->si_pid);
2732 err |= __put_user(from->si_uid, &to->si_uid);
2733 err |= __put_user(from->si_status, &to->si_status);
2734 err |= __put_user(from->si_utime, &to->si_utime);
2735 err |= __put_user(from->si_stime, &to->si_stime);
2736 break;
2737 case __SI_RT: /* This is not generated by the kernel as of now. */
2738 case __SI_MESGQ: /* But this is */
2739 err |= __put_user(from->si_pid, &to->si_pid);
2740 err |= __put_user(from->si_uid, &to->si_uid);
2741 err |= __put_user(from->si_ptr, &to->si_ptr);
2742 break;
2743#ifdef __ARCH_SIGSYS
2744 case __SI_SYS:
2745 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2746 err |= __put_user(from->si_syscall, &to->si_syscall);
2747 err |= __put_user(from->si_arch, &to->si_arch);
2748 break;
2749#endif
2750 default: /* this is just in case for now ... */
2751 err |= __put_user(from->si_pid, &to->si_pid);
2752 err |= __put_user(from->si_uid, &to->si_uid);
2753 break;
2754 }
2755 return err;
2756}
2757
2758#endif
2759
2760/**
2761 * do_sigtimedwait - wait for queued signals specified in @which
2762 * @which: queued signals to wait for
2763 * @info: if non-null, the signal's siginfo is returned here
2764 * @ts: upper bound on process time suspension
2765 */
2766int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2767 const struct timespec *ts)
2768{
2769 ktime_t *to = NULL, timeout = KTIME_MAX;
2770 struct task_struct *tsk = current;
2771 sigset_t mask = *which;
2772 int sig, ret = 0;
2773
2774 if (ts) {
2775 if (!timespec_valid(ts))
2776 return -EINVAL;
2777 timeout = timespec_to_ktime(*ts);
2778 to = &timeout;
2779 }
2780
2781 /*
2782 * Invert the set of allowed signals to get those we want to block.
2783 */
2784 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2785 signotset(&mask);
2786
2787 spin_lock_irq(&tsk->sighand->siglock);
2788 sig = dequeue_signal(tsk, &mask, info);
2789 if (!sig && timeout) {
2790 /*
2791 * None ready, temporarily unblock those we're interested
2792 * while we are sleeping in so that we'll be awakened when
2793 * they arrive. Unblocking is always fine, we can avoid
2794 * set_current_blocked().
2795 */
2796 tsk->real_blocked = tsk->blocked;
2797 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2798 recalc_sigpending();
2799 spin_unlock_irq(&tsk->sighand->siglock);
2800
2801 __set_current_state(TASK_INTERRUPTIBLE);
2802 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
2803 HRTIMER_MODE_REL);
2804 spin_lock_irq(&tsk->sighand->siglock);
2805 __set_task_blocked(tsk, &tsk->real_blocked);
2806 sigemptyset(&tsk->real_blocked);
2807 sig = dequeue_signal(tsk, &mask, info);
2808 }
2809 spin_unlock_irq(&tsk->sighand->siglock);
2810
2811 if (sig)
2812 return sig;
2813 return ret ? -EINTR : -EAGAIN;
2814}
2815
2816/**
2817 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2818 * in @uthese
2819 * @uthese: queued signals to wait for
2820 * @uinfo: if non-null, the signal's siginfo is returned here
2821 * @uts: upper bound on process time suspension
2822 * @sigsetsize: size of sigset_t type
2823 */
2824SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2825 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2826 size_t, sigsetsize)
2827{
2828 sigset_t these;
2829 struct timespec ts;
2830 siginfo_t info;
2831 int ret;
2832
2833 /* XXX: Don't preclude handling different sized sigset_t's. */
2834 if (sigsetsize != sizeof(sigset_t))
2835 return -EINVAL;
2836
2837 if (copy_from_user(&these, uthese, sizeof(these)))
2838 return -EFAULT;
2839
2840 if (uts) {
2841 if (copy_from_user(&ts, uts, sizeof(ts)))
2842 return -EFAULT;
2843 }
2844
2845 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2846
2847 if (ret > 0 && uinfo) {
2848 if (copy_siginfo_to_user(uinfo, &info))
2849 ret = -EFAULT;
2850 }
2851
2852 return ret;
2853}
2854
2855/**
2856 * sys_kill - send a signal to a process
2857 * @pid: the PID of the process
2858 * @sig: signal to be sent
2859 */
2860SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2861{
2862 struct siginfo info;
2863
2864 info.si_signo = sig;
2865 info.si_errno = 0;
2866 info.si_code = SI_USER;
2867 info.si_pid = task_tgid_vnr(current);
2868 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2869
2870 return kill_something_info(sig, &info, pid);
2871}
2872
2873static int
2874do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2875{
2876 struct task_struct *p;
2877 int error = -ESRCH;
2878
2879 rcu_read_lock();
2880 p = find_task_by_vpid(pid);
2881 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2882 error = check_kill_permission(sig, info, p);
2883 /*
2884 * The null signal is a permissions and process existence
2885 * probe. No signal is actually delivered.
2886 */
2887 if (!error && sig) {
2888 error = do_send_sig_info(sig, info, p, false);
2889 /*
2890 * If lock_task_sighand() failed we pretend the task
2891 * dies after receiving the signal. The window is tiny,
2892 * and the signal is private anyway.
2893 */
2894 if (unlikely(error == -ESRCH))
2895 error = 0;
2896 }
2897 }
2898 rcu_read_unlock();
2899
2900 return error;
2901}
2902
2903static int do_tkill(pid_t tgid, pid_t pid, int sig)
2904{
2905 struct siginfo info = {};
2906
2907 info.si_signo = sig;
2908 info.si_errno = 0;
2909 info.si_code = SI_TKILL;
2910 info.si_pid = task_tgid_vnr(current);
2911 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2912
2913 return do_send_specific(tgid, pid, sig, &info);
2914}
2915
2916/**
2917 * sys_tgkill - send signal to one specific thread
2918 * @tgid: the thread group ID of the thread
2919 * @pid: the PID of the thread
2920 * @sig: signal to be sent
2921 *
2922 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2923 * exists but it's not belonging to the target process anymore. This
2924 * method solves the problem of threads exiting and PIDs getting reused.
2925 */
2926SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2927{
2928 /* This is only valid for single tasks */
2929 if (pid <= 0 || tgid <= 0)
2930 return -EINVAL;
2931
2932 return do_tkill(tgid, pid, sig);
2933}
2934
2935/**
2936 * sys_tkill - send signal to one specific task
2937 * @pid: the PID of the task
2938 * @sig: signal to be sent
2939 *
2940 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2941 */
2942SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2943{
2944 /* This is only valid for single tasks */
2945 if (pid <= 0)
2946 return -EINVAL;
2947
2948 return do_tkill(0, pid, sig);
2949}
2950
2951static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2952{
2953 /* Not even root can pretend to send signals from the kernel.
2954 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2955 */
2956 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2957 (task_pid_vnr(current) != pid))
2958 return -EPERM;
2959
2960 info->si_signo = sig;
2961
2962 /* POSIX.1b doesn't mention process groups. */
2963 return kill_proc_info(sig, info, pid);
2964}
2965
2966/**
2967 * sys_rt_sigqueueinfo - send signal information to a signal
2968 * @pid: the PID of the thread
2969 * @sig: signal to be sent
2970 * @uinfo: signal info to be sent
2971 */
2972SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2973 siginfo_t __user *, uinfo)
2974{
2975 siginfo_t info;
2976 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2977 return -EFAULT;
2978 return do_rt_sigqueueinfo(pid, sig, &info);
2979}
2980
2981#ifdef CONFIG_COMPAT
2982COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
2983 compat_pid_t, pid,
2984 int, sig,
2985 struct compat_siginfo __user *, uinfo)
2986{
2987 siginfo_t info = {};
2988 int ret = copy_siginfo_from_user32(&info, uinfo);
2989 if (unlikely(ret))
2990 return ret;
2991 return do_rt_sigqueueinfo(pid, sig, &info);
2992}
2993#endif
2994
2995static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2996{
2997 /* This is only valid for single tasks */
2998 if (pid <= 0 || tgid <= 0)
2999 return -EINVAL;
3000
3001 /* Not even root can pretend to send signals from the kernel.
3002 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3003 */
3004 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3005 (task_pid_vnr(current) != pid))
3006 return -EPERM;
3007
3008 info->si_signo = sig;
3009
3010 return do_send_specific(tgid, pid, sig, info);
3011}
3012
3013SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3014 siginfo_t __user *, uinfo)
3015{
3016 siginfo_t info;
3017
3018 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3019 return -EFAULT;
3020
3021 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3022}
3023
3024#ifdef CONFIG_COMPAT
3025COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3026 compat_pid_t, tgid,
3027 compat_pid_t, pid,
3028 int, sig,
3029 struct compat_siginfo __user *, uinfo)
3030{
3031 siginfo_t info = {};
3032
3033 if (copy_siginfo_from_user32(&info, uinfo))
3034 return -EFAULT;
3035 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3036}
3037#endif
3038
3039/*
3040 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3041 */
3042void kernel_sigaction(int sig, __sighandler_t action)
3043{
3044 spin_lock_irq(¤t->sighand->siglock);
3045 current->sighand->action[sig - 1].sa.sa_handler = action;
3046 if (action == SIG_IGN) {
3047 sigset_t mask;
3048
3049 sigemptyset(&mask);
3050 sigaddset(&mask, sig);
3051
3052 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3053 flush_sigqueue_mask(&mask, ¤t->pending);
3054 recalc_sigpending();
3055 }
3056 spin_unlock_irq(¤t->sighand->siglock);
3057}
3058EXPORT_SYMBOL(kernel_sigaction);
3059
3060void __weak sigaction_compat_abi(struct k_sigaction *act,
3061 struct k_sigaction *oact)
3062{
3063}
3064
3065int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3066{
3067 struct task_struct *p = current, *t;
3068 struct k_sigaction *k;
3069 sigset_t mask;
3070
3071 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3072 return -EINVAL;
3073
3074 k = &p->sighand->action[sig-1];
3075
3076 spin_lock_irq(&p->sighand->siglock);
3077 if (oact)
3078 *oact = *k;
3079
3080 sigaction_compat_abi(act, oact);
3081
3082 if (act) {
3083 sigdelsetmask(&act->sa.sa_mask,
3084 sigmask(SIGKILL) | sigmask(SIGSTOP));
3085 *k = *act;
3086 /*
3087 * POSIX 3.3.1.3:
3088 * "Setting a signal action to SIG_IGN for a signal that is
3089 * pending shall cause the pending signal to be discarded,
3090 * whether or not it is blocked."
3091 *
3092 * "Setting a signal action to SIG_DFL for a signal that is
3093 * pending and whose default action is to ignore the signal
3094 * (for example, SIGCHLD), shall cause the pending signal to
3095 * be discarded, whether or not it is blocked"
3096 */
3097 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3098 sigemptyset(&mask);
3099 sigaddset(&mask, sig);
3100 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3101 for_each_thread(p, t)
3102 flush_sigqueue_mask(&mask, &t->pending);
3103 }
3104 }
3105
3106 spin_unlock_irq(&p->sighand->siglock);
3107 return 0;
3108}
3109
3110static int
3111do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3112{
3113 stack_t oss;
3114 int error;
3115
3116 oss.ss_sp = (void __user *) current->sas_ss_sp;
3117 oss.ss_size = current->sas_ss_size;
3118 oss.ss_flags = sas_ss_flags(sp) |
3119 (current->sas_ss_flags & SS_FLAG_BITS);
3120
3121 if (uss) {
3122 void __user *ss_sp;
3123 size_t ss_size;
3124 unsigned ss_flags;
3125 int ss_mode;
3126
3127 error = -EFAULT;
3128 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3129 goto out;
3130 error = __get_user(ss_sp, &uss->ss_sp) |
3131 __get_user(ss_flags, &uss->ss_flags) |
3132 __get_user(ss_size, &uss->ss_size);
3133 if (error)
3134 goto out;
3135
3136 error = -EPERM;
3137 if (on_sig_stack(sp))
3138 goto out;
3139
3140 ss_mode = ss_flags & ~SS_FLAG_BITS;
3141 error = -EINVAL;
3142 if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3143 ss_mode != 0)
3144 goto out;
3145
3146 if (ss_mode == SS_DISABLE) {
3147 ss_size = 0;
3148 ss_sp = NULL;
3149 } else {
3150 error = -ENOMEM;
3151 if (ss_size < MINSIGSTKSZ)
3152 goto out;
3153 }
3154
3155 current->sas_ss_sp = (unsigned long) ss_sp;
3156 current->sas_ss_size = ss_size;
3157 current->sas_ss_flags = ss_flags;
3158 }
3159
3160 error = 0;
3161 if (uoss) {
3162 error = -EFAULT;
3163 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3164 goto out;
3165 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3166 __put_user(oss.ss_size, &uoss->ss_size) |
3167 __put_user(oss.ss_flags, &uoss->ss_flags);
3168 }
3169
3170out:
3171 return error;
3172}
3173SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3174{
3175 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3176}
3177
3178int restore_altstack(const stack_t __user *uss)
3179{
3180 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3181 /* squash all but EFAULT for now */
3182 return err == -EFAULT ? err : 0;
3183}
3184
3185int __save_altstack(stack_t __user *uss, unsigned long sp)
3186{
3187 struct task_struct *t = current;
3188 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3189 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3190 __put_user(t->sas_ss_size, &uss->ss_size);
3191 if (err)
3192 return err;
3193 if (t->sas_ss_flags & SS_AUTODISARM)
3194 sas_ss_reset(t);
3195 return 0;
3196}
3197
3198#ifdef CONFIG_COMPAT
3199COMPAT_SYSCALL_DEFINE2(sigaltstack,
3200 const compat_stack_t __user *, uss_ptr,
3201 compat_stack_t __user *, uoss_ptr)
3202{
3203 stack_t uss, uoss;
3204 int ret;
3205 mm_segment_t seg;
3206
3207 if (uss_ptr) {
3208 compat_stack_t uss32;
3209
3210 memset(&uss, 0, sizeof(stack_t));
3211 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3212 return -EFAULT;
3213 uss.ss_sp = compat_ptr(uss32.ss_sp);
3214 uss.ss_flags = uss32.ss_flags;
3215 uss.ss_size = uss32.ss_size;
3216 }
3217 seg = get_fs();
3218 set_fs(KERNEL_DS);
3219 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3220 (stack_t __force __user *) &uoss,
3221 compat_user_stack_pointer());
3222 set_fs(seg);
3223 if (ret >= 0 && uoss_ptr) {
3224 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3225 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3226 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3227 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3228 ret = -EFAULT;
3229 }
3230 return ret;
3231}
3232
3233int compat_restore_altstack(const compat_stack_t __user *uss)
3234{
3235 int err = compat_sys_sigaltstack(uss, NULL);
3236 /* squash all but -EFAULT for now */
3237 return err == -EFAULT ? err : 0;
3238}
3239
3240int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3241{
3242 int err;
3243 struct task_struct *t = current;
3244 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3245 &uss->ss_sp) |
3246 __put_user(t->sas_ss_flags, &uss->ss_flags) |
3247 __put_user(t->sas_ss_size, &uss->ss_size);
3248 if (err)
3249 return err;
3250 if (t->sas_ss_flags & SS_AUTODISARM)
3251 sas_ss_reset(t);
3252 return 0;
3253}
3254#endif
3255
3256#ifdef __ARCH_WANT_SYS_SIGPENDING
3257
3258/**
3259 * sys_sigpending - examine pending signals
3260 * @set: where mask of pending signal is returned
3261 */
3262SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3263{
3264 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3265}
3266
3267#endif
3268
3269#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3270/**
3271 * sys_sigprocmask - examine and change blocked signals
3272 * @how: whether to add, remove, or set signals
3273 * @nset: signals to add or remove (if non-null)
3274 * @oset: previous value of signal mask if non-null
3275 *
3276 * Some platforms have their own version with special arguments;
3277 * others support only sys_rt_sigprocmask.
3278 */
3279
3280SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3281 old_sigset_t __user *, oset)
3282{
3283 old_sigset_t old_set, new_set;
3284 sigset_t new_blocked;
3285
3286 old_set = current->blocked.sig[0];
3287
3288 if (nset) {
3289 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3290 return -EFAULT;
3291
3292 new_blocked = current->blocked;
3293
3294 switch (how) {
3295 case SIG_BLOCK:
3296 sigaddsetmask(&new_blocked, new_set);
3297 break;
3298 case SIG_UNBLOCK:
3299 sigdelsetmask(&new_blocked, new_set);
3300 break;
3301 case SIG_SETMASK:
3302 new_blocked.sig[0] = new_set;
3303 break;
3304 default:
3305 return -EINVAL;
3306 }
3307
3308 set_current_blocked(&new_blocked);
3309 }
3310
3311 if (oset) {
3312 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3313 return -EFAULT;
3314 }
3315
3316 return 0;
3317}
3318#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3319
3320#ifndef CONFIG_ODD_RT_SIGACTION
3321/**
3322 * sys_rt_sigaction - alter an action taken by a process
3323 * @sig: signal to be sent
3324 * @act: new sigaction
3325 * @oact: used to save the previous sigaction
3326 * @sigsetsize: size of sigset_t type
3327 */
3328SYSCALL_DEFINE4(rt_sigaction, int, sig,
3329 const struct sigaction __user *, act,
3330 struct sigaction __user *, oact,
3331 size_t, sigsetsize)
3332{
3333 struct k_sigaction new_sa, old_sa;
3334 int ret = -EINVAL;
3335
3336 /* XXX: Don't preclude handling different sized sigset_t's. */
3337 if (sigsetsize != sizeof(sigset_t))
3338 goto out;
3339
3340 if (act) {
3341 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3342 return -EFAULT;
3343 }
3344
3345 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3346
3347 if (!ret && oact) {
3348 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3349 return -EFAULT;
3350 }
3351out:
3352 return ret;
3353}
3354#ifdef CONFIG_COMPAT
3355COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3356 const struct compat_sigaction __user *, act,
3357 struct compat_sigaction __user *, oact,
3358 compat_size_t, sigsetsize)
3359{
3360 struct k_sigaction new_ka, old_ka;
3361 compat_sigset_t mask;
3362#ifdef __ARCH_HAS_SA_RESTORER
3363 compat_uptr_t restorer;
3364#endif
3365 int ret;
3366
3367 /* XXX: Don't preclude handling different sized sigset_t's. */
3368 if (sigsetsize != sizeof(compat_sigset_t))
3369 return -EINVAL;
3370
3371 if (act) {
3372 compat_uptr_t handler;
3373 ret = get_user(handler, &act->sa_handler);
3374 new_ka.sa.sa_handler = compat_ptr(handler);
3375#ifdef __ARCH_HAS_SA_RESTORER
3376 ret |= get_user(restorer, &act->sa_restorer);
3377 new_ka.sa.sa_restorer = compat_ptr(restorer);
3378#endif
3379 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3380 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3381 if (ret)
3382 return -EFAULT;
3383 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3384 }
3385
3386 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3387 if (!ret && oact) {
3388 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3389 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3390 &oact->sa_handler);
3391 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3392 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3393#ifdef __ARCH_HAS_SA_RESTORER
3394 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3395 &oact->sa_restorer);
3396#endif
3397 }
3398 return ret;
3399}
3400#endif
3401#endif /* !CONFIG_ODD_RT_SIGACTION */
3402
3403#ifdef CONFIG_OLD_SIGACTION
3404SYSCALL_DEFINE3(sigaction, int, sig,
3405 const struct old_sigaction __user *, act,
3406 struct old_sigaction __user *, oact)
3407{
3408 struct k_sigaction new_ka, old_ka;
3409 int ret;
3410
3411 if (act) {
3412 old_sigset_t mask;
3413 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3414 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3415 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3416 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3417 __get_user(mask, &act->sa_mask))
3418 return -EFAULT;
3419#ifdef __ARCH_HAS_KA_RESTORER
3420 new_ka.ka_restorer = NULL;
3421#endif
3422 siginitset(&new_ka.sa.sa_mask, mask);
3423 }
3424
3425 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3426
3427 if (!ret && oact) {
3428 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3429 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3430 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3431 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3432 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3433 return -EFAULT;
3434 }
3435
3436 return ret;
3437}
3438#endif
3439#ifdef CONFIG_COMPAT_OLD_SIGACTION
3440COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3441 const struct compat_old_sigaction __user *, act,
3442 struct compat_old_sigaction __user *, oact)
3443{
3444 struct k_sigaction new_ka, old_ka;
3445 int ret;
3446 compat_old_sigset_t mask;
3447 compat_uptr_t handler, restorer;
3448
3449 if (act) {
3450 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3451 __get_user(handler, &act->sa_handler) ||
3452 __get_user(restorer, &act->sa_restorer) ||
3453 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3454 __get_user(mask, &act->sa_mask))
3455 return -EFAULT;
3456
3457#ifdef __ARCH_HAS_KA_RESTORER
3458 new_ka.ka_restorer = NULL;
3459#endif
3460 new_ka.sa.sa_handler = compat_ptr(handler);
3461 new_ka.sa.sa_restorer = compat_ptr(restorer);
3462 siginitset(&new_ka.sa.sa_mask, mask);
3463 }
3464
3465 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3466
3467 if (!ret && oact) {
3468 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3469 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3470 &oact->sa_handler) ||
3471 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3472 &oact->sa_restorer) ||
3473 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3474 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3475 return -EFAULT;
3476 }
3477 return ret;
3478}
3479#endif
3480
3481#ifdef CONFIG_SGETMASK_SYSCALL
3482
3483/*
3484 * For backwards compatibility. Functionality superseded by sigprocmask.
3485 */
3486SYSCALL_DEFINE0(sgetmask)
3487{
3488 /* SMP safe */
3489 return current->blocked.sig[0];
3490}
3491
3492SYSCALL_DEFINE1(ssetmask, int, newmask)
3493{
3494 int old = current->blocked.sig[0];
3495 sigset_t newset;
3496
3497 siginitset(&newset, newmask);
3498 set_current_blocked(&newset);
3499
3500 return old;
3501}
3502#endif /* CONFIG_SGETMASK_SYSCALL */
3503
3504#ifdef __ARCH_WANT_SYS_SIGNAL
3505/*
3506 * For backwards compatibility. Functionality superseded by sigaction.
3507 */
3508SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3509{
3510 struct k_sigaction new_sa, old_sa;
3511 int ret;
3512
3513 new_sa.sa.sa_handler = handler;
3514 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3515 sigemptyset(&new_sa.sa.sa_mask);
3516
3517 ret = do_sigaction(sig, &new_sa, &old_sa);
3518
3519 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3520}
3521#endif /* __ARCH_WANT_SYS_SIGNAL */
3522
3523#ifdef __ARCH_WANT_SYS_PAUSE
3524
3525SYSCALL_DEFINE0(pause)
3526{
3527 while (!signal_pending(current)) {
3528 __set_current_state(TASK_INTERRUPTIBLE);
3529 schedule();
3530 }
3531 return -ERESTARTNOHAND;
3532}
3533
3534#endif
3535
3536static int sigsuspend(sigset_t *set)
3537{
3538 current->saved_sigmask = current->blocked;
3539 set_current_blocked(set);
3540
3541 while (!signal_pending(current)) {
3542 __set_current_state(TASK_INTERRUPTIBLE);
3543 schedule();
3544 }
3545 set_restore_sigmask();
3546 return -ERESTARTNOHAND;
3547}
3548
3549/**
3550 * sys_rt_sigsuspend - replace the signal mask for a value with the
3551 * @unewset value until a signal is received
3552 * @unewset: new signal mask value
3553 * @sigsetsize: size of sigset_t type
3554 */
3555SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3556{
3557 sigset_t newset;
3558
3559 /* XXX: Don't preclude handling different sized sigset_t's. */
3560 if (sigsetsize != sizeof(sigset_t))
3561 return -EINVAL;
3562
3563 if (copy_from_user(&newset, unewset, sizeof(newset)))
3564 return -EFAULT;
3565 return sigsuspend(&newset);
3566}
3567
3568#ifdef CONFIG_COMPAT
3569COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3570{
3571#ifdef __BIG_ENDIAN
3572 sigset_t newset;
3573 compat_sigset_t newset32;
3574
3575 /* XXX: Don't preclude handling different sized sigset_t's. */
3576 if (sigsetsize != sizeof(sigset_t))
3577 return -EINVAL;
3578
3579 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3580 return -EFAULT;
3581 sigset_from_compat(&newset, &newset32);
3582 return sigsuspend(&newset);
3583#else
3584 /* on little-endian bitmaps don't care about granularity */
3585 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3586#endif
3587}
3588#endif
3589
3590#ifdef CONFIG_OLD_SIGSUSPEND
3591SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3592{
3593 sigset_t blocked;
3594 siginitset(&blocked, mask);
3595 return sigsuspend(&blocked);
3596}
3597#endif
3598#ifdef CONFIG_OLD_SIGSUSPEND3
3599SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3600{
3601 sigset_t blocked;
3602 siginitset(&blocked, mask);
3603 return sigsuspend(&blocked);
3604}
3605#endif
3606
3607__weak const char *arch_vma_name(struct vm_area_struct *vma)
3608{
3609 return NULL;
3610}
3611
3612void __init signals_init(void)
3613{
3614 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3615 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3616 != offsetof(struct siginfo, _sifields._pad));
3617
3618 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3619}
3620
3621#ifdef CONFIG_KGDB_KDB
3622#include <linux/kdb.h>
3623/*
3624 * kdb_send_sig_info - Allows kdb to send signals without exposing
3625 * signal internals. This function checks if the required locks are
3626 * available before calling the main signal code, to avoid kdb
3627 * deadlocks.
3628 */
3629void
3630kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3631{
3632 static struct task_struct *kdb_prev_t;
3633 int sig, new_t;
3634 if (!spin_trylock(&t->sighand->siglock)) {
3635 kdb_printf("Can't do kill command now.\n"
3636 "The sigmask lock is held somewhere else in "
3637 "kernel, try again later\n");
3638 return;
3639 }
3640 spin_unlock(&t->sighand->siglock);
3641 new_t = kdb_prev_t != t;
3642 kdb_prev_t = t;
3643 if (t->state != TASK_RUNNING && new_t) {
3644 kdb_printf("Process is not RUNNING, sending a signal from "
3645 "kdb risks deadlock\n"
3646 "on the run queue locks. "
3647 "The signal has _not_ been sent.\n"
3648 "Reissue the kill command if you want to risk "
3649 "the deadlock.\n");
3650 return;
3651 }
3652 sig = info->si_signo;
3653 if (send_sig_info(sig, info, t))
3654 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3655 sig, t->pid);
3656 else
3657 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3658}
3659#endif /* CONFIG_KGDB_KDB */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
12 */
13
14#include <linux/slab.h>
15#include <linux/export.h>
16#include <linux/init.h>
17#include <linux/sched/mm.h>
18#include <linux/sched/user.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/sched/cputime.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/proc_fs.h>
26#include <linux/tty.h>
27#include <linux/binfmts.h>
28#include <linux/coredump.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/ptrace.h>
32#include <linux/signal.h>
33#include <linux/signalfd.h>
34#include <linux/ratelimit.h>
35#include <linux/tracehook.h>
36#include <linux/capability.h>
37#include <linux/freezer.h>
38#include <linux/pid_namespace.h>
39#include <linux/nsproxy.h>
40#include <linux/user_namespace.h>
41#include <linux/uprobes.h>
42#include <linux/compat.h>
43#include <linux/cn_proc.h>
44#include <linux/compiler.h>
45#include <linux/posix-timers.h>
46#include <linux/cgroup.h>
47#include <linux/audit.h>
48
49#define CREATE_TRACE_POINTS
50#include <trace/events/signal.h>
51
52#include <asm/param.h>
53#include <linux/uaccess.h>
54#include <asm/unistd.h>
55#include <asm/siginfo.h>
56#include <asm/cacheflush.h>
57
58/*
59 * SLAB caches for signal bits.
60 */
61
62static struct kmem_cache *sigqueue_cachep;
63
64int print_fatal_signals __read_mostly;
65
66static void __user *sig_handler(struct task_struct *t, int sig)
67{
68 return t->sighand->action[sig - 1].sa.sa_handler;
69}
70
71static inline bool sig_handler_ignored(void __user *handler, int sig)
72{
73 /* Is it explicitly or implicitly ignored? */
74 return handler == SIG_IGN ||
75 (handler == SIG_DFL && sig_kernel_ignore(sig));
76}
77
78static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
79{
80 void __user *handler;
81
82 handler = sig_handler(t, sig);
83
84 /* SIGKILL and SIGSTOP may not be sent to the global init */
85 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
86 return true;
87
88 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
89 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
90 return true;
91
92 /* Only allow kernel generated signals to this kthread */
93 if (unlikely((t->flags & PF_KTHREAD) &&
94 (handler == SIG_KTHREAD_KERNEL) && !force))
95 return true;
96
97 return sig_handler_ignored(handler, sig);
98}
99
100static bool sig_ignored(struct task_struct *t, int sig, bool force)
101{
102 /*
103 * Blocked signals are never ignored, since the
104 * signal handler may change by the time it is
105 * unblocked.
106 */
107 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
108 return false;
109
110 /*
111 * Tracers may want to know about even ignored signal unless it
112 * is SIGKILL which can't be reported anyway but can be ignored
113 * by SIGNAL_UNKILLABLE task.
114 */
115 if (t->ptrace && sig != SIGKILL)
116 return false;
117
118 return sig_task_ignored(t, sig, force);
119}
120
121/*
122 * Re-calculate pending state from the set of locally pending
123 * signals, globally pending signals, and blocked signals.
124 */
125static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
126{
127 unsigned long ready;
128 long i;
129
130 switch (_NSIG_WORDS) {
131 default:
132 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
133 ready |= signal->sig[i] &~ blocked->sig[i];
134 break;
135
136 case 4: ready = signal->sig[3] &~ blocked->sig[3];
137 ready |= signal->sig[2] &~ blocked->sig[2];
138 ready |= signal->sig[1] &~ blocked->sig[1];
139 ready |= signal->sig[0] &~ blocked->sig[0];
140 break;
141
142 case 2: ready = signal->sig[1] &~ blocked->sig[1];
143 ready |= signal->sig[0] &~ blocked->sig[0];
144 break;
145
146 case 1: ready = signal->sig[0] &~ blocked->sig[0];
147 }
148 return ready != 0;
149}
150
151#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
152
153static bool recalc_sigpending_tsk(struct task_struct *t)
154{
155 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
156 PENDING(&t->pending, &t->blocked) ||
157 PENDING(&t->signal->shared_pending, &t->blocked) ||
158 cgroup_task_frozen(t)) {
159 set_tsk_thread_flag(t, TIF_SIGPENDING);
160 return true;
161 }
162
163 /*
164 * We must never clear the flag in another thread, or in current
165 * when it's possible the current syscall is returning -ERESTART*.
166 * So we don't clear it here, and only callers who know they should do.
167 */
168 return false;
169}
170
171/*
172 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
173 * This is superfluous when called on current, the wakeup is a harmless no-op.
174 */
175void recalc_sigpending_and_wake(struct task_struct *t)
176{
177 if (recalc_sigpending_tsk(t))
178 signal_wake_up(t, 0);
179}
180
181void recalc_sigpending(void)
182{
183 if (!recalc_sigpending_tsk(current) && !freezing(current))
184 clear_thread_flag(TIF_SIGPENDING);
185
186}
187EXPORT_SYMBOL(recalc_sigpending);
188
189void calculate_sigpending(void)
190{
191 /* Have any signals or users of TIF_SIGPENDING been delayed
192 * until after fork?
193 */
194 spin_lock_irq(¤t->sighand->siglock);
195 set_tsk_thread_flag(current, TIF_SIGPENDING);
196 recalc_sigpending();
197 spin_unlock_irq(¤t->sighand->siglock);
198}
199
200/* Given the mask, find the first available signal that should be serviced. */
201
202#define SYNCHRONOUS_MASK \
203 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
204 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
205
206int next_signal(struct sigpending *pending, sigset_t *mask)
207{
208 unsigned long i, *s, *m, x;
209 int sig = 0;
210
211 s = pending->signal.sig;
212 m = mask->sig;
213
214 /*
215 * Handle the first word specially: it contains the
216 * synchronous signals that need to be dequeued first.
217 */
218 x = *s &~ *m;
219 if (x) {
220 if (x & SYNCHRONOUS_MASK)
221 x &= SYNCHRONOUS_MASK;
222 sig = ffz(~x) + 1;
223 return sig;
224 }
225
226 switch (_NSIG_WORDS) {
227 default:
228 for (i = 1; i < _NSIG_WORDS; ++i) {
229 x = *++s &~ *++m;
230 if (!x)
231 continue;
232 sig = ffz(~x) + i*_NSIG_BPW + 1;
233 break;
234 }
235 break;
236
237 case 2:
238 x = s[1] &~ m[1];
239 if (!x)
240 break;
241 sig = ffz(~x) + _NSIG_BPW + 1;
242 break;
243
244 case 1:
245 /* Nothing to do */
246 break;
247 }
248
249 return sig;
250}
251
252static inline void print_dropped_signal(int sig)
253{
254 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
255
256 if (!print_fatal_signals)
257 return;
258
259 if (!__ratelimit(&ratelimit_state))
260 return;
261
262 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
263 current->comm, current->pid, sig);
264}
265
266/**
267 * task_set_jobctl_pending - set jobctl pending bits
268 * @task: target task
269 * @mask: pending bits to set
270 *
271 * Clear @mask from @task->jobctl. @mask must be subset of
272 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
273 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
274 * cleared. If @task is already being killed or exiting, this function
275 * becomes noop.
276 *
277 * CONTEXT:
278 * Must be called with @task->sighand->siglock held.
279 *
280 * RETURNS:
281 * %true if @mask is set, %false if made noop because @task was dying.
282 */
283bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
284{
285 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
286 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
287 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
288
289 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
290 return false;
291
292 if (mask & JOBCTL_STOP_SIGMASK)
293 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
294
295 task->jobctl |= mask;
296 return true;
297}
298
299/**
300 * task_clear_jobctl_trapping - clear jobctl trapping bit
301 * @task: target task
302 *
303 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
304 * Clear it and wake up the ptracer. Note that we don't need any further
305 * locking. @task->siglock guarantees that @task->parent points to the
306 * ptracer.
307 *
308 * CONTEXT:
309 * Must be called with @task->sighand->siglock held.
310 */
311void task_clear_jobctl_trapping(struct task_struct *task)
312{
313 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
314 task->jobctl &= ~JOBCTL_TRAPPING;
315 smp_mb(); /* advised by wake_up_bit() */
316 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
317 }
318}
319
320/**
321 * task_clear_jobctl_pending - clear jobctl pending bits
322 * @task: target task
323 * @mask: pending bits to clear
324 *
325 * Clear @mask from @task->jobctl. @mask must be subset of
326 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
327 * STOP bits are cleared together.
328 *
329 * If clearing of @mask leaves no stop or trap pending, this function calls
330 * task_clear_jobctl_trapping().
331 *
332 * CONTEXT:
333 * Must be called with @task->sighand->siglock held.
334 */
335void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
336{
337 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
338
339 if (mask & JOBCTL_STOP_PENDING)
340 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
341
342 task->jobctl &= ~mask;
343
344 if (!(task->jobctl & JOBCTL_PENDING_MASK))
345 task_clear_jobctl_trapping(task);
346}
347
348/**
349 * task_participate_group_stop - participate in a group stop
350 * @task: task participating in a group stop
351 *
352 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
353 * Group stop states are cleared and the group stop count is consumed if
354 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
355 * stop, the appropriate `SIGNAL_*` flags are set.
356 *
357 * CONTEXT:
358 * Must be called with @task->sighand->siglock held.
359 *
360 * RETURNS:
361 * %true if group stop completion should be notified to the parent, %false
362 * otherwise.
363 */
364static bool task_participate_group_stop(struct task_struct *task)
365{
366 struct signal_struct *sig = task->signal;
367 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
368
369 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
370
371 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
372
373 if (!consume)
374 return false;
375
376 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
377 sig->group_stop_count--;
378
379 /*
380 * Tell the caller to notify completion iff we are entering into a
381 * fresh group stop. Read comment in do_signal_stop() for details.
382 */
383 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
384 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
385 return true;
386 }
387 return false;
388}
389
390void task_join_group_stop(struct task_struct *task)
391{
392 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
393 struct signal_struct *sig = current->signal;
394
395 if (sig->group_stop_count) {
396 sig->group_stop_count++;
397 mask |= JOBCTL_STOP_CONSUME;
398 } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
399 return;
400
401 /* Have the new thread join an on-going signal group stop */
402 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
403}
404
405/*
406 * allocate a new signal queue record
407 * - this may be called without locks if and only if t == current, otherwise an
408 * appropriate lock must be held to stop the target task from exiting
409 */
410static struct sigqueue *
411__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
412 int override_rlimit, const unsigned int sigqueue_flags)
413{
414 struct sigqueue *q = NULL;
415 struct ucounts *ucounts = NULL;
416 long sigpending;
417
418 /*
419 * Protect access to @t credentials. This can go away when all
420 * callers hold rcu read lock.
421 *
422 * NOTE! A pending signal will hold on to the user refcount,
423 * and we get/put the refcount only when the sigpending count
424 * changes from/to zero.
425 */
426 rcu_read_lock();
427 ucounts = task_ucounts(t);
428 sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
429 rcu_read_unlock();
430 if (!sigpending)
431 return NULL;
432
433 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
434 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
435 } else {
436 print_dropped_signal(sig);
437 }
438
439 if (unlikely(q == NULL)) {
440 dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
441 } else {
442 INIT_LIST_HEAD(&q->list);
443 q->flags = sigqueue_flags;
444 q->ucounts = ucounts;
445 }
446 return q;
447}
448
449static void __sigqueue_free(struct sigqueue *q)
450{
451 if (q->flags & SIGQUEUE_PREALLOC)
452 return;
453 if (q->ucounts) {
454 dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
455 q->ucounts = NULL;
456 }
457 kmem_cache_free(sigqueue_cachep, q);
458}
459
460void flush_sigqueue(struct sigpending *queue)
461{
462 struct sigqueue *q;
463
464 sigemptyset(&queue->signal);
465 while (!list_empty(&queue->list)) {
466 q = list_entry(queue->list.next, struct sigqueue , list);
467 list_del_init(&q->list);
468 __sigqueue_free(q);
469 }
470}
471
472/*
473 * Flush all pending signals for this kthread.
474 */
475void flush_signals(struct task_struct *t)
476{
477 unsigned long flags;
478
479 spin_lock_irqsave(&t->sighand->siglock, flags);
480 clear_tsk_thread_flag(t, TIF_SIGPENDING);
481 flush_sigqueue(&t->pending);
482 flush_sigqueue(&t->signal->shared_pending);
483 spin_unlock_irqrestore(&t->sighand->siglock, flags);
484}
485EXPORT_SYMBOL(flush_signals);
486
487#ifdef CONFIG_POSIX_TIMERS
488static void __flush_itimer_signals(struct sigpending *pending)
489{
490 sigset_t signal, retain;
491 struct sigqueue *q, *n;
492
493 signal = pending->signal;
494 sigemptyset(&retain);
495
496 list_for_each_entry_safe(q, n, &pending->list, list) {
497 int sig = q->info.si_signo;
498
499 if (likely(q->info.si_code != SI_TIMER)) {
500 sigaddset(&retain, sig);
501 } else {
502 sigdelset(&signal, sig);
503 list_del_init(&q->list);
504 __sigqueue_free(q);
505 }
506 }
507
508 sigorsets(&pending->signal, &signal, &retain);
509}
510
511void flush_itimer_signals(void)
512{
513 struct task_struct *tsk = current;
514 unsigned long flags;
515
516 spin_lock_irqsave(&tsk->sighand->siglock, flags);
517 __flush_itimer_signals(&tsk->pending);
518 __flush_itimer_signals(&tsk->signal->shared_pending);
519 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
520}
521#endif
522
523void ignore_signals(struct task_struct *t)
524{
525 int i;
526
527 for (i = 0; i < _NSIG; ++i)
528 t->sighand->action[i].sa.sa_handler = SIG_IGN;
529
530 flush_signals(t);
531}
532
533/*
534 * Flush all handlers for a task.
535 */
536
537void
538flush_signal_handlers(struct task_struct *t, int force_default)
539{
540 int i;
541 struct k_sigaction *ka = &t->sighand->action[0];
542 for (i = _NSIG ; i != 0 ; i--) {
543 if (force_default || ka->sa.sa_handler != SIG_IGN)
544 ka->sa.sa_handler = SIG_DFL;
545 ka->sa.sa_flags = 0;
546#ifdef __ARCH_HAS_SA_RESTORER
547 ka->sa.sa_restorer = NULL;
548#endif
549 sigemptyset(&ka->sa.sa_mask);
550 ka++;
551 }
552}
553
554bool unhandled_signal(struct task_struct *tsk, int sig)
555{
556 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
557 if (is_global_init(tsk))
558 return true;
559
560 if (handler != SIG_IGN && handler != SIG_DFL)
561 return false;
562
563 /* if ptraced, let the tracer determine */
564 return !tsk->ptrace;
565}
566
567static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
568 bool *resched_timer)
569{
570 struct sigqueue *q, *first = NULL;
571
572 /*
573 * Collect the siginfo appropriate to this signal. Check if
574 * there is another siginfo for the same signal.
575 */
576 list_for_each_entry(q, &list->list, list) {
577 if (q->info.si_signo == sig) {
578 if (first)
579 goto still_pending;
580 first = q;
581 }
582 }
583
584 sigdelset(&list->signal, sig);
585
586 if (first) {
587still_pending:
588 list_del_init(&first->list);
589 copy_siginfo(info, &first->info);
590
591 *resched_timer =
592 (first->flags & SIGQUEUE_PREALLOC) &&
593 (info->si_code == SI_TIMER) &&
594 (info->si_sys_private);
595
596 __sigqueue_free(first);
597 } else {
598 /*
599 * Ok, it wasn't in the queue. This must be
600 * a fast-pathed signal or we must have been
601 * out of queue space. So zero out the info.
602 */
603 clear_siginfo(info);
604 info->si_signo = sig;
605 info->si_errno = 0;
606 info->si_code = SI_USER;
607 info->si_pid = 0;
608 info->si_uid = 0;
609 }
610}
611
612static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
613 kernel_siginfo_t *info, bool *resched_timer)
614{
615 int sig = next_signal(pending, mask);
616
617 if (sig)
618 collect_signal(sig, pending, info, resched_timer);
619 return sig;
620}
621
622/*
623 * Dequeue a signal and return the element to the caller, which is
624 * expected to free it.
625 *
626 * All callers have to hold the siglock.
627 */
628int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
629{
630 bool resched_timer = false;
631 int signr;
632
633 /* We only dequeue private signals from ourselves, we don't let
634 * signalfd steal them
635 */
636 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
637 if (!signr) {
638 signr = __dequeue_signal(&tsk->signal->shared_pending,
639 mask, info, &resched_timer);
640#ifdef CONFIG_POSIX_TIMERS
641 /*
642 * itimer signal ?
643 *
644 * itimers are process shared and we restart periodic
645 * itimers in the signal delivery path to prevent DoS
646 * attacks in the high resolution timer case. This is
647 * compliant with the old way of self-restarting
648 * itimers, as the SIGALRM is a legacy signal and only
649 * queued once. Changing the restart behaviour to
650 * restart the timer in the signal dequeue path is
651 * reducing the timer noise on heavy loaded !highres
652 * systems too.
653 */
654 if (unlikely(signr == SIGALRM)) {
655 struct hrtimer *tmr = &tsk->signal->real_timer;
656
657 if (!hrtimer_is_queued(tmr) &&
658 tsk->signal->it_real_incr != 0) {
659 hrtimer_forward(tmr, tmr->base->get_time(),
660 tsk->signal->it_real_incr);
661 hrtimer_restart(tmr);
662 }
663 }
664#endif
665 }
666
667 recalc_sigpending();
668 if (!signr)
669 return 0;
670
671 if (unlikely(sig_kernel_stop(signr))) {
672 /*
673 * Set a marker that we have dequeued a stop signal. Our
674 * caller might release the siglock and then the pending
675 * stop signal it is about to process is no longer in the
676 * pending bitmasks, but must still be cleared by a SIGCONT
677 * (and overruled by a SIGKILL). So those cases clear this
678 * shared flag after we've set it. Note that this flag may
679 * remain set after the signal we return is ignored or
680 * handled. That doesn't matter because its only purpose
681 * is to alert stop-signal processing code when another
682 * processor has come along and cleared the flag.
683 */
684 current->jobctl |= JOBCTL_STOP_DEQUEUED;
685 }
686#ifdef CONFIG_POSIX_TIMERS
687 if (resched_timer) {
688 /*
689 * Release the siglock to ensure proper locking order
690 * of timer locks outside of siglocks. Note, we leave
691 * irqs disabled here, since the posix-timers code is
692 * about to disable them again anyway.
693 */
694 spin_unlock(&tsk->sighand->siglock);
695 posixtimer_rearm(info);
696 spin_lock(&tsk->sighand->siglock);
697
698 /* Don't expose the si_sys_private value to userspace */
699 info->si_sys_private = 0;
700 }
701#endif
702 return signr;
703}
704EXPORT_SYMBOL_GPL(dequeue_signal);
705
706static int dequeue_synchronous_signal(kernel_siginfo_t *info)
707{
708 struct task_struct *tsk = current;
709 struct sigpending *pending = &tsk->pending;
710 struct sigqueue *q, *sync = NULL;
711
712 /*
713 * Might a synchronous signal be in the queue?
714 */
715 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
716 return 0;
717
718 /*
719 * Return the first synchronous signal in the queue.
720 */
721 list_for_each_entry(q, &pending->list, list) {
722 /* Synchronous signals have a positive si_code */
723 if ((q->info.si_code > SI_USER) &&
724 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
725 sync = q;
726 goto next;
727 }
728 }
729 return 0;
730next:
731 /*
732 * Check if there is another siginfo for the same signal.
733 */
734 list_for_each_entry_continue(q, &pending->list, list) {
735 if (q->info.si_signo == sync->info.si_signo)
736 goto still_pending;
737 }
738
739 sigdelset(&pending->signal, sync->info.si_signo);
740 recalc_sigpending();
741still_pending:
742 list_del_init(&sync->list);
743 copy_siginfo(info, &sync->info);
744 __sigqueue_free(sync);
745 return info->si_signo;
746}
747
748/*
749 * Tell a process that it has a new active signal..
750 *
751 * NOTE! we rely on the previous spin_lock to
752 * lock interrupts for us! We can only be called with
753 * "siglock" held, and the local interrupt must
754 * have been disabled when that got acquired!
755 *
756 * No need to set need_resched since signal event passing
757 * goes through ->blocked
758 */
759void signal_wake_up_state(struct task_struct *t, unsigned int state)
760{
761 set_tsk_thread_flag(t, TIF_SIGPENDING);
762 /*
763 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
764 * case. We don't check t->state here because there is a race with it
765 * executing another processor and just now entering stopped state.
766 * By using wake_up_state, we ensure the process will wake up and
767 * handle its death signal.
768 */
769 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
770 kick_process(t);
771}
772
773/*
774 * Remove signals in mask from the pending set and queue.
775 * Returns 1 if any signals were found.
776 *
777 * All callers must be holding the siglock.
778 */
779static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
780{
781 struct sigqueue *q, *n;
782 sigset_t m;
783
784 sigandsets(&m, mask, &s->signal);
785 if (sigisemptyset(&m))
786 return;
787
788 sigandnsets(&s->signal, &s->signal, mask);
789 list_for_each_entry_safe(q, n, &s->list, list) {
790 if (sigismember(mask, q->info.si_signo)) {
791 list_del_init(&q->list);
792 __sigqueue_free(q);
793 }
794 }
795}
796
797static inline int is_si_special(const struct kernel_siginfo *info)
798{
799 return info <= SEND_SIG_PRIV;
800}
801
802static inline bool si_fromuser(const struct kernel_siginfo *info)
803{
804 return info == SEND_SIG_NOINFO ||
805 (!is_si_special(info) && SI_FROMUSER(info));
806}
807
808/*
809 * called with RCU read lock from check_kill_permission()
810 */
811static bool kill_ok_by_cred(struct task_struct *t)
812{
813 const struct cred *cred = current_cred();
814 const struct cred *tcred = __task_cred(t);
815
816 return uid_eq(cred->euid, tcred->suid) ||
817 uid_eq(cred->euid, tcred->uid) ||
818 uid_eq(cred->uid, tcred->suid) ||
819 uid_eq(cred->uid, tcred->uid) ||
820 ns_capable(tcred->user_ns, CAP_KILL);
821}
822
823/*
824 * Bad permissions for sending the signal
825 * - the caller must hold the RCU read lock
826 */
827static int check_kill_permission(int sig, struct kernel_siginfo *info,
828 struct task_struct *t)
829{
830 struct pid *sid;
831 int error;
832
833 if (!valid_signal(sig))
834 return -EINVAL;
835
836 if (!si_fromuser(info))
837 return 0;
838
839 error = audit_signal_info(sig, t); /* Let audit system see the signal */
840 if (error)
841 return error;
842
843 if (!same_thread_group(current, t) &&
844 !kill_ok_by_cred(t)) {
845 switch (sig) {
846 case SIGCONT:
847 sid = task_session(t);
848 /*
849 * We don't return the error if sid == NULL. The
850 * task was unhashed, the caller must notice this.
851 */
852 if (!sid || sid == task_session(current))
853 break;
854 fallthrough;
855 default:
856 return -EPERM;
857 }
858 }
859
860 return security_task_kill(t, info, sig, NULL);
861}
862
863/**
864 * ptrace_trap_notify - schedule trap to notify ptracer
865 * @t: tracee wanting to notify tracer
866 *
867 * This function schedules sticky ptrace trap which is cleared on the next
868 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
869 * ptracer.
870 *
871 * If @t is running, STOP trap will be taken. If trapped for STOP and
872 * ptracer is listening for events, tracee is woken up so that it can
873 * re-trap for the new event. If trapped otherwise, STOP trap will be
874 * eventually taken without returning to userland after the existing traps
875 * are finished by PTRACE_CONT.
876 *
877 * CONTEXT:
878 * Must be called with @task->sighand->siglock held.
879 */
880static void ptrace_trap_notify(struct task_struct *t)
881{
882 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
883 assert_spin_locked(&t->sighand->siglock);
884
885 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
886 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
887}
888
889/*
890 * Handle magic process-wide effects of stop/continue signals. Unlike
891 * the signal actions, these happen immediately at signal-generation
892 * time regardless of blocking, ignoring, or handling. This does the
893 * actual continuing for SIGCONT, but not the actual stopping for stop
894 * signals. The process stop is done as a signal action for SIG_DFL.
895 *
896 * Returns true if the signal should be actually delivered, otherwise
897 * it should be dropped.
898 */
899static bool prepare_signal(int sig, struct task_struct *p, bool force)
900{
901 struct signal_struct *signal = p->signal;
902 struct task_struct *t;
903 sigset_t flush;
904
905 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
906 if (!(signal->flags & SIGNAL_GROUP_EXIT))
907 return sig == SIGKILL;
908 /*
909 * The process is in the middle of dying, nothing to do.
910 */
911 } else if (sig_kernel_stop(sig)) {
912 /*
913 * This is a stop signal. Remove SIGCONT from all queues.
914 */
915 siginitset(&flush, sigmask(SIGCONT));
916 flush_sigqueue_mask(&flush, &signal->shared_pending);
917 for_each_thread(p, t)
918 flush_sigqueue_mask(&flush, &t->pending);
919 } else if (sig == SIGCONT) {
920 unsigned int why;
921 /*
922 * Remove all stop signals from all queues, wake all threads.
923 */
924 siginitset(&flush, SIG_KERNEL_STOP_MASK);
925 flush_sigqueue_mask(&flush, &signal->shared_pending);
926 for_each_thread(p, t) {
927 flush_sigqueue_mask(&flush, &t->pending);
928 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
929 if (likely(!(t->ptrace & PT_SEIZED)))
930 wake_up_state(t, __TASK_STOPPED);
931 else
932 ptrace_trap_notify(t);
933 }
934
935 /*
936 * Notify the parent with CLD_CONTINUED if we were stopped.
937 *
938 * If we were in the middle of a group stop, we pretend it
939 * was already finished, and then continued. Since SIGCHLD
940 * doesn't queue we report only CLD_STOPPED, as if the next
941 * CLD_CONTINUED was dropped.
942 */
943 why = 0;
944 if (signal->flags & SIGNAL_STOP_STOPPED)
945 why |= SIGNAL_CLD_CONTINUED;
946 else if (signal->group_stop_count)
947 why |= SIGNAL_CLD_STOPPED;
948
949 if (why) {
950 /*
951 * The first thread which returns from do_signal_stop()
952 * will take ->siglock, notice SIGNAL_CLD_MASK, and
953 * notify its parent. See get_signal().
954 */
955 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
956 signal->group_stop_count = 0;
957 signal->group_exit_code = 0;
958 }
959 }
960
961 return !sig_ignored(p, sig, force);
962}
963
964/*
965 * Test if P wants to take SIG. After we've checked all threads with this,
966 * it's equivalent to finding no threads not blocking SIG. Any threads not
967 * blocking SIG were ruled out because they are not running and already
968 * have pending signals. Such threads will dequeue from the shared queue
969 * as soon as they're available, so putting the signal on the shared queue
970 * will be equivalent to sending it to one such thread.
971 */
972static inline bool wants_signal(int sig, struct task_struct *p)
973{
974 if (sigismember(&p->blocked, sig))
975 return false;
976
977 if (p->flags & PF_EXITING)
978 return false;
979
980 if (sig == SIGKILL)
981 return true;
982
983 if (task_is_stopped_or_traced(p))
984 return false;
985
986 return task_curr(p) || !task_sigpending(p);
987}
988
989static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
990{
991 struct signal_struct *signal = p->signal;
992 struct task_struct *t;
993
994 /*
995 * Now find a thread we can wake up to take the signal off the queue.
996 *
997 * If the main thread wants the signal, it gets first crack.
998 * Probably the least surprising to the average bear.
999 */
1000 if (wants_signal(sig, p))
1001 t = p;
1002 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1003 /*
1004 * There is just one thread and it does not need to be woken.
1005 * It will dequeue unblocked signals before it runs again.
1006 */
1007 return;
1008 else {
1009 /*
1010 * Otherwise try to find a suitable thread.
1011 */
1012 t = signal->curr_target;
1013 while (!wants_signal(sig, t)) {
1014 t = next_thread(t);
1015 if (t == signal->curr_target)
1016 /*
1017 * No thread needs to be woken.
1018 * Any eligible threads will see
1019 * the signal in the queue soon.
1020 */
1021 return;
1022 }
1023 signal->curr_target = t;
1024 }
1025
1026 /*
1027 * Found a killable thread. If the signal will be fatal,
1028 * then start taking the whole group down immediately.
1029 */
1030 if (sig_fatal(p, sig) &&
1031 !(signal->flags & SIGNAL_GROUP_EXIT) &&
1032 !sigismember(&t->real_blocked, sig) &&
1033 (sig == SIGKILL || !p->ptrace)) {
1034 /*
1035 * This signal will be fatal to the whole group.
1036 */
1037 if (!sig_kernel_coredump(sig)) {
1038 /*
1039 * Start a group exit and wake everybody up.
1040 * This way we don't have other threads
1041 * running and doing things after a slower
1042 * thread has the fatal signal pending.
1043 */
1044 signal->flags = SIGNAL_GROUP_EXIT;
1045 signal->group_exit_code = sig;
1046 signal->group_stop_count = 0;
1047 t = p;
1048 do {
1049 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1050 sigaddset(&t->pending.signal, SIGKILL);
1051 signal_wake_up(t, 1);
1052 } while_each_thread(p, t);
1053 return;
1054 }
1055 }
1056
1057 /*
1058 * The signal is already in the shared-pending queue.
1059 * Tell the chosen thread to wake up and dequeue it.
1060 */
1061 signal_wake_up(t, sig == SIGKILL);
1062 return;
1063}
1064
1065static inline bool legacy_queue(struct sigpending *signals, int sig)
1066{
1067 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1068}
1069
1070static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1071 enum pid_type type, bool force)
1072{
1073 struct sigpending *pending;
1074 struct sigqueue *q;
1075 int override_rlimit;
1076 int ret = 0, result;
1077
1078 assert_spin_locked(&t->sighand->siglock);
1079
1080 result = TRACE_SIGNAL_IGNORED;
1081 if (!prepare_signal(sig, t, force))
1082 goto ret;
1083
1084 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1085 /*
1086 * Short-circuit ignored signals and support queuing
1087 * exactly one non-rt signal, so that we can get more
1088 * detailed information about the cause of the signal.
1089 */
1090 result = TRACE_SIGNAL_ALREADY_PENDING;
1091 if (legacy_queue(pending, sig))
1092 goto ret;
1093
1094 result = TRACE_SIGNAL_DELIVERED;
1095 /*
1096 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1097 */
1098 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1099 goto out_set;
1100
1101 /*
1102 * Real-time signals must be queued if sent by sigqueue, or
1103 * some other real-time mechanism. It is implementation
1104 * defined whether kill() does so. We attempt to do so, on
1105 * the principle of least surprise, but since kill is not
1106 * allowed to fail with EAGAIN when low on memory we just
1107 * make sure at least one signal gets delivered and don't
1108 * pass on the info struct.
1109 */
1110 if (sig < SIGRTMIN)
1111 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1112 else
1113 override_rlimit = 0;
1114
1115 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1116
1117 if (q) {
1118 list_add_tail(&q->list, &pending->list);
1119 switch ((unsigned long) info) {
1120 case (unsigned long) SEND_SIG_NOINFO:
1121 clear_siginfo(&q->info);
1122 q->info.si_signo = sig;
1123 q->info.si_errno = 0;
1124 q->info.si_code = SI_USER;
1125 q->info.si_pid = task_tgid_nr_ns(current,
1126 task_active_pid_ns(t));
1127 rcu_read_lock();
1128 q->info.si_uid =
1129 from_kuid_munged(task_cred_xxx(t, user_ns),
1130 current_uid());
1131 rcu_read_unlock();
1132 break;
1133 case (unsigned long) SEND_SIG_PRIV:
1134 clear_siginfo(&q->info);
1135 q->info.si_signo = sig;
1136 q->info.si_errno = 0;
1137 q->info.si_code = SI_KERNEL;
1138 q->info.si_pid = 0;
1139 q->info.si_uid = 0;
1140 break;
1141 default:
1142 copy_siginfo(&q->info, info);
1143 break;
1144 }
1145 } else if (!is_si_special(info) &&
1146 sig >= SIGRTMIN && info->si_code != SI_USER) {
1147 /*
1148 * Queue overflow, abort. We may abort if the
1149 * signal was rt and sent by user using something
1150 * other than kill().
1151 */
1152 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1153 ret = -EAGAIN;
1154 goto ret;
1155 } else {
1156 /*
1157 * This is a silent loss of information. We still
1158 * send the signal, but the *info bits are lost.
1159 */
1160 result = TRACE_SIGNAL_LOSE_INFO;
1161 }
1162
1163out_set:
1164 signalfd_notify(t, sig);
1165 sigaddset(&pending->signal, sig);
1166
1167 /* Let multiprocess signals appear after on-going forks */
1168 if (type > PIDTYPE_TGID) {
1169 struct multiprocess_signals *delayed;
1170 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1171 sigset_t *signal = &delayed->signal;
1172 /* Can't queue both a stop and a continue signal */
1173 if (sig == SIGCONT)
1174 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1175 else if (sig_kernel_stop(sig))
1176 sigdelset(signal, SIGCONT);
1177 sigaddset(signal, sig);
1178 }
1179 }
1180
1181 complete_signal(sig, t, type);
1182ret:
1183 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1184 return ret;
1185}
1186
1187static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1188{
1189 bool ret = false;
1190 switch (siginfo_layout(info->si_signo, info->si_code)) {
1191 case SIL_KILL:
1192 case SIL_CHLD:
1193 case SIL_RT:
1194 ret = true;
1195 break;
1196 case SIL_TIMER:
1197 case SIL_POLL:
1198 case SIL_FAULT:
1199 case SIL_FAULT_TRAPNO:
1200 case SIL_FAULT_MCEERR:
1201 case SIL_FAULT_BNDERR:
1202 case SIL_FAULT_PKUERR:
1203 case SIL_PERF_EVENT:
1204 case SIL_SYS:
1205 ret = false;
1206 break;
1207 }
1208 return ret;
1209}
1210
1211static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1212 enum pid_type type)
1213{
1214 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1215 bool force = false;
1216
1217 if (info == SEND_SIG_NOINFO) {
1218 /* Force if sent from an ancestor pid namespace */
1219 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1220 } else if (info == SEND_SIG_PRIV) {
1221 /* Don't ignore kernel generated signals */
1222 force = true;
1223 } else if (has_si_pid_and_uid(info)) {
1224 /* SIGKILL and SIGSTOP is special or has ids */
1225 struct user_namespace *t_user_ns;
1226
1227 rcu_read_lock();
1228 t_user_ns = task_cred_xxx(t, user_ns);
1229 if (current_user_ns() != t_user_ns) {
1230 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1231 info->si_uid = from_kuid_munged(t_user_ns, uid);
1232 }
1233 rcu_read_unlock();
1234
1235 /* A kernel generated signal? */
1236 force = (info->si_code == SI_KERNEL);
1237
1238 /* From an ancestor pid namespace? */
1239 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1240 info->si_pid = 0;
1241 force = true;
1242 }
1243 }
1244 return __send_signal(sig, info, t, type, force);
1245}
1246
1247static void print_fatal_signal(int signr)
1248{
1249 struct pt_regs *regs = signal_pt_regs();
1250 pr_info("potentially unexpected fatal signal %d.\n", signr);
1251
1252#if defined(__i386__) && !defined(__arch_um__)
1253 pr_info("code at %08lx: ", regs->ip);
1254 {
1255 int i;
1256 for (i = 0; i < 16; i++) {
1257 unsigned char insn;
1258
1259 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1260 break;
1261 pr_cont("%02x ", insn);
1262 }
1263 }
1264 pr_cont("\n");
1265#endif
1266 preempt_disable();
1267 show_regs(regs);
1268 preempt_enable();
1269}
1270
1271static int __init setup_print_fatal_signals(char *str)
1272{
1273 get_option (&str, &print_fatal_signals);
1274
1275 return 1;
1276}
1277
1278__setup("print-fatal-signals=", setup_print_fatal_signals);
1279
1280int
1281__group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1282{
1283 return send_signal(sig, info, p, PIDTYPE_TGID);
1284}
1285
1286int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1287 enum pid_type type)
1288{
1289 unsigned long flags;
1290 int ret = -ESRCH;
1291
1292 if (lock_task_sighand(p, &flags)) {
1293 ret = send_signal(sig, info, p, type);
1294 unlock_task_sighand(p, &flags);
1295 }
1296
1297 return ret;
1298}
1299
1300/*
1301 * Force a signal that the process can't ignore: if necessary
1302 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1303 *
1304 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1305 * since we do not want to have a signal handler that was blocked
1306 * be invoked when user space had explicitly blocked it.
1307 *
1308 * We don't want to have recursive SIGSEGV's etc, for example,
1309 * that is why we also clear SIGNAL_UNKILLABLE.
1310 */
1311static int
1312force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
1313{
1314 unsigned long int flags;
1315 int ret, blocked, ignored;
1316 struct k_sigaction *action;
1317 int sig = info->si_signo;
1318
1319 spin_lock_irqsave(&t->sighand->siglock, flags);
1320 action = &t->sighand->action[sig-1];
1321 ignored = action->sa.sa_handler == SIG_IGN;
1322 blocked = sigismember(&t->blocked, sig);
1323 if (blocked || ignored) {
1324 action->sa.sa_handler = SIG_DFL;
1325 if (blocked) {
1326 sigdelset(&t->blocked, sig);
1327 recalc_sigpending_and_wake(t);
1328 }
1329 }
1330 /*
1331 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1332 * debugging to leave init killable.
1333 */
1334 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1335 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1336 ret = send_signal(sig, info, t, PIDTYPE_PID);
1337 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1338
1339 return ret;
1340}
1341
1342int force_sig_info(struct kernel_siginfo *info)
1343{
1344 return force_sig_info_to_task(info, current);
1345}
1346
1347/*
1348 * Nuke all other threads in the group.
1349 */
1350int zap_other_threads(struct task_struct *p)
1351{
1352 struct task_struct *t = p;
1353 int count = 0;
1354
1355 p->signal->group_stop_count = 0;
1356
1357 while_each_thread(p, t) {
1358 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1359 count++;
1360
1361 /* Don't bother with already dead threads */
1362 if (t->exit_state)
1363 continue;
1364 sigaddset(&t->pending.signal, SIGKILL);
1365 signal_wake_up(t, 1);
1366 }
1367
1368 return count;
1369}
1370
1371struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1372 unsigned long *flags)
1373{
1374 struct sighand_struct *sighand;
1375
1376 rcu_read_lock();
1377 for (;;) {
1378 sighand = rcu_dereference(tsk->sighand);
1379 if (unlikely(sighand == NULL))
1380 break;
1381
1382 /*
1383 * This sighand can be already freed and even reused, but
1384 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1385 * initializes ->siglock: this slab can't go away, it has
1386 * the same object type, ->siglock can't be reinitialized.
1387 *
1388 * We need to ensure that tsk->sighand is still the same
1389 * after we take the lock, we can race with de_thread() or
1390 * __exit_signal(). In the latter case the next iteration
1391 * must see ->sighand == NULL.
1392 */
1393 spin_lock_irqsave(&sighand->siglock, *flags);
1394 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1395 break;
1396 spin_unlock_irqrestore(&sighand->siglock, *flags);
1397 }
1398 rcu_read_unlock();
1399
1400 return sighand;
1401}
1402
1403/*
1404 * send signal info to all the members of a group
1405 */
1406int group_send_sig_info(int sig, struct kernel_siginfo *info,
1407 struct task_struct *p, enum pid_type type)
1408{
1409 int ret;
1410
1411 rcu_read_lock();
1412 ret = check_kill_permission(sig, info, p);
1413 rcu_read_unlock();
1414
1415 if (!ret && sig)
1416 ret = do_send_sig_info(sig, info, p, type);
1417
1418 return ret;
1419}
1420
1421/*
1422 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1423 * control characters do (^C, ^Z etc)
1424 * - the caller must hold at least a readlock on tasklist_lock
1425 */
1426int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1427{
1428 struct task_struct *p = NULL;
1429 int retval, success;
1430
1431 success = 0;
1432 retval = -ESRCH;
1433 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1434 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1435 success |= !err;
1436 retval = err;
1437 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1438 return success ? 0 : retval;
1439}
1440
1441int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1442{
1443 int error = -ESRCH;
1444 struct task_struct *p;
1445
1446 for (;;) {
1447 rcu_read_lock();
1448 p = pid_task(pid, PIDTYPE_PID);
1449 if (p)
1450 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1451 rcu_read_unlock();
1452 if (likely(!p || error != -ESRCH))
1453 return error;
1454
1455 /*
1456 * The task was unhashed in between, try again. If it
1457 * is dead, pid_task() will return NULL, if we race with
1458 * de_thread() it will find the new leader.
1459 */
1460 }
1461}
1462
1463static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1464{
1465 int error;
1466 rcu_read_lock();
1467 error = kill_pid_info(sig, info, find_vpid(pid));
1468 rcu_read_unlock();
1469 return error;
1470}
1471
1472static inline bool kill_as_cred_perm(const struct cred *cred,
1473 struct task_struct *target)
1474{
1475 const struct cred *pcred = __task_cred(target);
1476
1477 return uid_eq(cred->euid, pcred->suid) ||
1478 uid_eq(cred->euid, pcred->uid) ||
1479 uid_eq(cred->uid, pcred->suid) ||
1480 uid_eq(cred->uid, pcred->uid);
1481}
1482
1483/*
1484 * The usb asyncio usage of siginfo is wrong. The glibc support
1485 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1486 * AKA after the generic fields:
1487 * kernel_pid_t si_pid;
1488 * kernel_uid32_t si_uid;
1489 * sigval_t si_value;
1490 *
1491 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1492 * after the generic fields is:
1493 * void __user *si_addr;
1494 *
1495 * This is a practical problem when there is a 64bit big endian kernel
1496 * and a 32bit userspace. As the 32bit address will encoded in the low
1497 * 32bits of the pointer. Those low 32bits will be stored at higher
1498 * address than appear in a 32 bit pointer. So userspace will not
1499 * see the address it was expecting for it's completions.
1500 *
1501 * There is nothing in the encoding that can allow
1502 * copy_siginfo_to_user32 to detect this confusion of formats, so
1503 * handle this by requiring the caller of kill_pid_usb_asyncio to
1504 * notice when this situration takes place and to store the 32bit
1505 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1506 * parameter.
1507 */
1508int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1509 struct pid *pid, const struct cred *cred)
1510{
1511 struct kernel_siginfo info;
1512 struct task_struct *p;
1513 unsigned long flags;
1514 int ret = -EINVAL;
1515
1516 if (!valid_signal(sig))
1517 return ret;
1518
1519 clear_siginfo(&info);
1520 info.si_signo = sig;
1521 info.si_errno = errno;
1522 info.si_code = SI_ASYNCIO;
1523 *((sigval_t *)&info.si_pid) = addr;
1524
1525 rcu_read_lock();
1526 p = pid_task(pid, PIDTYPE_PID);
1527 if (!p) {
1528 ret = -ESRCH;
1529 goto out_unlock;
1530 }
1531 if (!kill_as_cred_perm(cred, p)) {
1532 ret = -EPERM;
1533 goto out_unlock;
1534 }
1535 ret = security_task_kill(p, &info, sig, cred);
1536 if (ret)
1537 goto out_unlock;
1538
1539 if (sig) {
1540 if (lock_task_sighand(p, &flags)) {
1541 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1542 unlock_task_sighand(p, &flags);
1543 } else
1544 ret = -ESRCH;
1545 }
1546out_unlock:
1547 rcu_read_unlock();
1548 return ret;
1549}
1550EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1551
1552/*
1553 * kill_something_info() interprets pid in interesting ways just like kill(2).
1554 *
1555 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1556 * is probably wrong. Should make it like BSD or SYSV.
1557 */
1558
1559static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1560{
1561 int ret;
1562
1563 if (pid > 0)
1564 return kill_proc_info(sig, info, pid);
1565
1566 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1567 if (pid == INT_MIN)
1568 return -ESRCH;
1569
1570 read_lock(&tasklist_lock);
1571 if (pid != -1) {
1572 ret = __kill_pgrp_info(sig, info,
1573 pid ? find_vpid(-pid) : task_pgrp(current));
1574 } else {
1575 int retval = 0, count = 0;
1576 struct task_struct * p;
1577
1578 for_each_process(p) {
1579 if (task_pid_vnr(p) > 1 &&
1580 !same_thread_group(p, current)) {
1581 int err = group_send_sig_info(sig, info, p,
1582 PIDTYPE_MAX);
1583 ++count;
1584 if (err != -EPERM)
1585 retval = err;
1586 }
1587 }
1588 ret = count ? retval : -ESRCH;
1589 }
1590 read_unlock(&tasklist_lock);
1591
1592 return ret;
1593}
1594
1595/*
1596 * These are for backward compatibility with the rest of the kernel source.
1597 */
1598
1599int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1600{
1601 /*
1602 * Make sure legacy kernel users don't send in bad values
1603 * (normal paths check this in check_kill_permission).
1604 */
1605 if (!valid_signal(sig))
1606 return -EINVAL;
1607
1608 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1609}
1610EXPORT_SYMBOL(send_sig_info);
1611
1612#define __si_special(priv) \
1613 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1614
1615int
1616send_sig(int sig, struct task_struct *p, int priv)
1617{
1618 return send_sig_info(sig, __si_special(priv), p);
1619}
1620EXPORT_SYMBOL(send_sig);
1621
1622void force_sig(int sig)
1623{
1624 struct kernel_siginfo info;
1625
1626 clear_siginfo(&info);
1627 info.si_signo = sig;
1628 info.si_errno = 0;
1629 info.si_code = SI_KERNEL;
1630 info.si_pid = 0;
1631 info.si_uid = 0;
1632 force_sig_info(&info);
1633}
1634EXPORT_SYMBOL(force_sig);
1635
1636/*
1637 * When things go south during signal handling, we
1638 * will force a SIGSEGV. And if the signal that caused
1639 * the problem was already a SIGSEGV, we'll want to
1640 * make sure we don't even try to deliver the signal..
1641 */
1642void force_sigsegv(int sig)
1643{
1644 struct task_struct *p = current;
1645
1646 if (sig == SIGSEGV) {
1647 unsigned long flags;
1648 spin_lock_irqsave(&p->sighand->siglock, flags);
1649 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1650 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1651 }
1652 force_sig(SIGSEGV);
1653}
1654
1655int force_sig_fault_to_task(int sig, int code, void __user *addr
1656 ___ARCH_SI_TRAPNO(int trapno)
1657 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1658 , struct task_struct *t)
1659{
1660 struct kernel_siginfo info;
1661
1662 clear_siginfo(&info);
1663 info.si_signo = sig;
1664 info.si_errno = 0;
1665 info.si_code = code;
1666 info.si_addr = addr;
1667#ifdef __ARCH_SI_TRAPNO
1668 info.si_trapno = trapno;
1669#endif
1670#ifdef __ia64__
1671 info.si_imm = imm;
1672 info.si_flags = flags;
1673 info.si_isr = isr;
1674#endif
1675 return force_sig_info_to_task(&info, t);
1676}
1677
1678int force_sig_fault(int sig, int code, void __user *addr
1679 ___ARCH_SI_TRAPNO(int trapno)
1680 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1681{
1682 return force_sig_fault_to_task(sig, code, addr
1683 ___ARCH_SI_TRAPNO(trapno)
1684 ___ARCH_SI_IA64(imm, flags, isr), current);
1685}
1686
1687int send_sig_fault(int sig, int code, void __user *addr
1688 ___ARCH_SI_TRAPNO(int trapno)
1689 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1690 , struct task_struct *t)
1691{
1692 struct kernel_siginfo info;
1693
1694 clear_siginfo(&info);
1695 info.si_signo = sig;
1696 info.si_errno = 0;
1697 info.si_code = code;
1698 info.si_addr = addr;
1699#ifdef __ARCH_SI_TRAPNO
1700 info.si_trapno = trapno;
1701#endif
1702#ifdef __ia64__
1703 info.si_imm = imm;
1704 info.si_flags = flags;
1705 info.si_isr = isr;
1706#endif
1707 return send_sig_info(info.si_signo, &info, t);
1708}
1709
1710int force_sig_mceerr(int code, void __user *addr, short lsb)
1711{
1712 struct kernel_siginfo info;
1713
1714 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1715 clear_siginfo(&info);
1716 info.si_signo = SIGBUS;
1717 info.si_errno = 0;
1718 info.si_code = code;
1719 info.si_addr = addr;
1720 info.si_addr_lsb = lsb;
1721 return force_sig_info(&info);
1722}
1723
1724int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1725{
1726 struct kernel_siginfo info;
1727
1728 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1729 clear_siginfo(&info);
1730 info.si_signo = SIGBUS;
1731 info.si_errno = 0;
1732 info.si_code = code;
1733 info.si_addr = addr;
1734 info.si_addr_lsb = lsb;
1735 return send_sig_info(info.si_signo, &info, t);
1736}
1737EXPORT_SYMBOL(send_sig_mceerr);
1738
1739int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1740{
1741 struct kernel_siginfo info;
1742
1743 clear_siginfo(&info);
1744 info.si_signo = SIGSEGV;
1745 info.si_errno = 0;
1746 info.si_code = SEGV_BNDERR;
1747 info.si_addr = addr;
1748 info.si_lower = lower;
1749 info.si_upper = upper;
1750 return force_sig_info(&info);
1751}
1752
1753#ifdef SEGV_PKUERR
1754int force_sig_pkuerr(void __user *addr, u32 pkey)
1755{
1756 struct kernel_siginfo info;
1757
1758 clear_siginfo(&info);
1759 info.si_signo = SIGSEGV;
1760 info.si_errno = 0;
1761 info.si_code = SEGV_PKUERR;
1762 info.si_addr = addr;
1763 info.si_pkey = pkey;
1764 return force_sig_info(&info);
1765}
1766#endif
1767
1768int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
1769{
1770 struct kernel_siginfo info;
1771
1772 clear_siginfo(&info);
1773 info.si_signo = SIGTRAP;
1774 info.si_errno = 0;
1775 info.si_code = TRAP_PERF;
1776 info.si_addr = addr;
1777 info.si_perf_data = sig_data;
1778 info.si_perf_type = type;
1779
1780 return force_sig_info(&info);
1781}
1782
1783/* For the crazy architectures that include trap information in
1784 * the errno field, instead of an actual errno value.
1785 */
1786int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1787{
1788 struct kernel_siginfo info;
1789
1790 clear_siginfo(&info);
1791 info.si_signo = SIGTRAP;
1792 info.si_errno = errno;
1793 info.si_code = TRAP_HWBKPT;
1794 info.si_addr = addr;
1795 return force_sig_info(&info);
1796}
1797
1798int kill_pgrp(struct pid *pid, int sig, int priv)
1799{
1800 int ret;
1801
1802 read_lock(&tasklist_lock);
1803 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1804 read_unlock(&tasklist_lock);
1805
1806 return ret;
1807}
1808EXPORT_SYMBOL(kill_pgrp);
1809
1810int kill_pid(struct pid *pid, int sig, int priv)
1811{
1812 return kill_pid_info(sig, __si_special(priv), pid);
1813}
1814EXPORT_SYMBOL(kill_pid);
1815
1816/*
1817 * These functions support sending signals using preallocated sigqueue
1818 * structures. This is needed "because realtime applications cannot
1819 * afford to lose notifications of asynchronous events, like timer
1820 * expirations or I/O completions". In the case of POSIX Timers
1821 * we allocate the sigqueue structure from the timer_create. If this
1822 * allocation fails we are able to report the failure to the application
1823 * with an EAGAIN error.
1824 */
1825struct sigqueue *sigqueue_alloc(void)
1826{
1827 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1828}
1829
1830void sigqueue_free(struct sigqueue *q)
1831{
1832 unsigned long flags;
1833 spinlock_t *lock = ¤t->sighand->siglock;
1834
1835 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1836 /*
1837 * We must hold ->siglock while testing q->list
1838 * to serialize with collect_signal() or with
1839 * __exit_signal()->flush_sigqueue().
1840 */
1841 spin_lock_irqsave(lock, flags);
1842 q->flags &= ~SIGQUEUE_PREALLOC;
1843 /*
1844 * If it is queued it will be freed when dequeued,
1845 * like the "regular" sigqueue.
1846 */
1847 if (!list_empty(&q->list))
1848 q = NULL;
1849 spin_unlock_irqrestore(lock, flags);
1850
1851 if (q)
1852 __sigqueue_free(q);
1853}
1854
1855int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1856{
1857 int sig = q->info.si_signo;
1858 struct sigpending *pending;
1859 struct task_struct *t;
1860 unsigned long flags;
1861 int ret, result;
1862
1863 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1864
1865 ret = -1;
1866 rcu_read_lock();
1867 t = pid_task(pid, type);
1868 if (!t || !likely(lock_task_sighand(t, &flags)))
1869 goto ret;
1870
1871 ret = 1; /* the signal is ignored */
1872 result = TRACE_SIGNAL_IGNORED;
1873 if (!prepare_signal(sig, t, false))
1874 goto out;
1875
1876 ret = 0;
1877 if (unlikely(!list_empty(&q->list))) {
1878 /*
1879 * If an SI_TIMER entry is already queue just increment
1880 * the overrun count.
1881 */
1882 BUG_ON(q->info.si_code != SI_TIMER);
1883 q->info.si_overrun++;
1884 result = TRACE_SIGNAL_ALREADY_PENDING;
1885 goto out;
1886 }
1887 q->info.si_overrun = 0;
1888
1889 signalfd_notify(t, sig);
1890 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1891 list_add_tail(&q->list, &pending->list);
1892 sigaddset(&pending->signal, sig);
1893 complete_signal(sig, t, type);
1894 result = TRACE_SIGNAL_DELIVERED;
1895out:
1896 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1897 unlock_task_sighand(t, &flags);
1898ret:
1899 rcu_read_unlock();
1900 return ret;
1901}
1902
1903static void do_notify_pidfd(struct task_struct *task)
1904{
1905 struct pid *pid;
1906
1907 WARN_ON(task->exit_state == 0);
1908 pid = task_pid(task);
1909 wake_up_all(&pid->wait_pidfd);
1910}
1911
1912/*
1913 * Let a parent know about the death of a child.
1914 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1915 *
1916 * Returns true if our parent ignored us and so we've switched to
1917 * self-reaping.
1918 */
1919bool do_notify_parent(struct task_struct *tsk, int sig)
1920{
1921 struct kernel_siginfo info;
1922 unsigned long flags;
1923 struct sighand_struct *psig;
1924 bool autoreap = false;
1925 u64 utime, stime;
1926
1927 BUG_ON(sig == -1);
1928
1929 /* do_notify_parent_cldstop should have been called instead. */
1930 BUG_ON(task_is_stopped_or_traced(tsk));
1931
1932 BUG_ON(!tsk->ptrace &&
1933 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1934
1935 /* Wake up all pidfd waiters */
1936 do_notify_pidfd(tsk);
1937
1938 if (sig != SIGCHLD) {
1939 /*
1940 * This is only possible if parent == real_parent.
1941 * Check if it has changed security domain.
1942 */
1943 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
1944 sig = SIGCHLD;
1945 }
1946
1947 clear_siginfo(&info);
1948 info.si_signo = sig;
1949 info.si_errno = 0;
1950 /*
1951 * We are under tasklist_lock here so our parent is tied to
1952 * us and cannot change.
1953 *
1954 * task_active_pid_ns will always return the same pid namespace
1955 * until a task passes through release_task.
1956 *
1957 * write_lock() currently calls preempt_disable() which is the
1958 * same as rcu_read_lock(), but according to Oleg, this is not
1959 * correct to rely on this
1960 */
1961 rcu_read_lock();
1962 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1963 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1964 task_uid(tsk));
1965 rcu_read_unlock();
1966
1967 task_cputime(tsk, &utime, &stime);
1968 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1969 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1970
1971 info.si_status = tsk->exit_code & 0x7f;
1972 if (tsk->exit_code & 0x80)
1973 info.si_code = CLD_DUMPED;
1974 else if (tsk->exit_code & 0x7f)
1975 info.si_code = CLD_KILLED;
1976 else {
1977 info.si_code = CLD_EXITED;
1978 info.si_status = tsk->exit_code >> 8;
1979 }
1980
1981 psig = tsk->parent->sighand;
1982 spin_lock_irqsave(&psig->siglock, flags);
1983 if (!tsk->ptrace && sig == SIGCHLD &&
1984 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1985 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1986 /*
1987 * We are exiting and our parent doesn't care. POSIX.1
1988 * defines special semantics for setting SIGCHLD to SIG_IGN
1989 * or setting the SA_NOCLDWAIT flag: we should be reaped
1990 * automatically and not left for our parent's wait4 call.
1991 * Rather than having the parent do it as a magic kind of
1992 * signal handler, we just set this to tell do_exit that we
1993 * can be cleaned up without becoming a zombie. Note that
1994 * we still call __wake_up_parent in this case, because a
1995 * blocked sys_wait4 might now return -ECHILD.
1996 *
1997 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1998 * is implementation-defined: we do (if you don't want
1999 * it, just use SIG_IGN instead).
2000 */
2001 autoreap = true;
2002 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2003 sig = 0;
2004 }
2005 /*
2006 * Send with __send_signal as si_pid and si_uid are in the
2007 * parent's namespaces.
2008 */
2009 if (valid_signal(sig) && sig)
2010 __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2011 __wake_up_parent(tsk, tsk->parent);
2012 spin_unlock_irqrestore(&psig->siglock, flags);
2013
2014 return autoreap;
2015}
2016
2017/**
2018 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2019 * @tsk: task reporting the state change
2020 * @for_ptracer: the notification is for ptracer
2021 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2022 *
2023 * Notify @tsk's parent that the stopped/continued state has changed. If
2024 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2025 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2026 *
2027 * CONTEXT:
2028 * Must be called with tasklist_lock at least read locked.
2029 */
2030static void do_notify_parent_cldstop(struct task_struct *tsk,
2031 bool for_ptracer, int why)
2032{
2033 struct kernel_siginfo info;
2034 unsigned long flags;
2035 struct task_struct *parent;
2036 struct sighand_struct *sighand;
2037 u64 utime, stime;
2038
2039 if (for_ptracer) {
2040 parent = tsk->parent;
2041 } else {
2042 tsk = tsk->group_leader;
2043 parent = tsk->real_parent;
2044 }
2045
2046 clear_siginfo(&info);
2047 info.si_signo = SIGCHLD;
2048 info.si_errno = 0;
2049 /*
2050 * see comment in do_notify_parent() about the following 4 lines
2051 */
2052 rcu_read_lock();
2053 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2054 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2055 rcu_read_unlock();
2056
2057 task_cputime(tsk, &utime, &stime);
2058 info.si_utime = nsec_to_clock_t(utime);
2059 info.si_stime = nsec_to_clock_t(stime);
2060
2061 info.si_code = why;
2062 switch (why) {
2063 case CLD_CONTINUED:
2064 info.si_status = SIGCONT;
2065 break;
2066 case CLD_STOPPED:
2067 info.si_status = tsk->signal->group_exit_code & 0x7f;
2068 break;
2069 case CLD_TRAPPED:
2070 info.si_status = tsk->exit_code & 0x7f;
2071 break;
2072 default:
2073 BUG();
2074 }
2075
2076 sighand = parent->sighand;
2077 spin_lock_irqsave(&sighand->siglock, flags);
2078 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2079 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2080 __group_send_sig_info(SIGCHLD, &info, parent);
2081 /*
2082 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2083 */
2084 __wake_up_parent(tsk, parent);
2085 spin_unlock_irqrestore(&sighand->siglock, flags);
2086}
2087
2088static inline bool may_ptrace_stop(void)
2089{
2090 if (!likely(current->ptrace))
2091 return false;
2092 /*
2093 * Are we in the middle of do_coredump?
2094 * If so and our tracer is also part of the coredump stopping
2095 * is a deadlock situation, and pointless because our tracer
2096 * is dead so don't allow us to stop.
2097 * If SIGKILL was already sent before the caller unlocked
2098 * ->siglock we must see ->core_state != NULL. Otherwise it
2099 * is safe to enter schedule().
2100 *
2101 * This is almost outdated, a task with the pending SIGKILL can't
2102 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
2103 * after SIGKILL was already dequeued.
2104 */
2105 if (unlikely(current->mm->core_state) &&
2106 unlikely(current->mm == current->parent->mm))
2107 return false;
2108
2109 return true;
2110}
2111
2112/*
2113 * Return non-zero if there is a SIGKILL that should be waking us up.
2114 * Called with the siglock held.
2115 */
2116static bool sigkill_pending(struct task_struct *tsk)
2117{
2118 return sigismember(&tsk->pending.signal, SIGKILL) ||
2119 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
2120}
2121
2122/*
2123 * This must be called with current->sighand->siglock held.
2124 *
2125 * This should be the path for all ptrace stops.
2126 * We always set current->last_siginfo while stopped here.
2127 * That makes it a way to test a stopped process for
2128 * being ptrace-stopped vs being job-control-stopped.
2129 *
2130 * If we actually decide not to stop at all because the tracer
2131 * is gone, we keep current->exit_code unless clear_code.
2132 */
2133static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
2134 __releases(¤t->sighand->siglock)
2135 __acquires(¤t->sighand->siglock)
2136{
2137 bool gstop_done = false;
2138
2139 if (arch_ptrace_stop_needed(exit_code, info)) {
2140 /*
2141 * The arch code has something special to do before a
2142 * ptrace stop. This is allowed to block, e.g. for faults
2143 * on user stack pages. We can't keep the siglock while
2144 * calling arch_ptrace_stop, so we must release it now.
2145 * To preserve proper semantics, we must do this before
2146 * any signal bookkeeping like checking group_stop_count.
2147 * Meanwhile, a SIGKILL could come in before we retake the
2148 * siglock. That must prevent us from sleeping in TASK_TRACED.
2149 * So after regaining the lock, we must check for SIGKILL.
2150 */
2151 spin_unlock_irq(¤t->sighand->siglock);
2152 arch_ptrace_stop(exit_code, info);
2153 spin_lock_irq(¤t->sighand->siglock);
2154 if (sigkill_pending(current))
2155 return;
2156 }
2157
2158 set_special_state(TASK_TRACED);
2159
2160 /*
2161 * We're committing to trapping. TRACED should be visible before
2162 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2163 * Also, transition to TRACED and updates to ->jobctl should be
2164 * atomic with respect to siglock and should be done after the arch
2165 * hook as siglock is released and regrabbed across it.
2166 *
2167 * TRACER TRACEE
2168 *
2169 * ptrace_attach()
2170 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2171 * do_wait()
2172 * set_current_state() smp_wmb();
2173 * ptrace_do_wait()
2174 * wait_task_stopped()
2175 * task_stopped_code()
2176 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2177 */
2178 smp_wmb();
2179
2180 current->last_siginfo = info;
2181 current->exit_code = exit_code;
2182
2183 /*
2184 * If @why is CLD_STOPPED, we're trapping to participate in a group
2185 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2186 * across siglock relocks since INTERRUPT was scheduled, PENDING
2187 * could be clear now. We act as if SIGCONT is received after
2188 * TASK_TRACED is entered - ignore it.
2189 */
2190 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2191 gstop_done = task_participate_group_stop(current);
2192
2193 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2194 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2195 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2196 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2197
2198 /* entering a trap, clear TRAPPING */
2199 task_clear_jobctl_trapping(current);
2200
2201 spin_unlock_irq(¤t->sighand->siglock);
2202 read_lock(&tasklist_lock);
2203 if (may_ptrace_stop()) {
2204 /*
2205 * Notify parents of the stop.
2206 *
2207 * While ptraced, there are two parents - the ptracer and
2208 * the real_parent of the group_leader. The ptracer should
2209 * know about every stop while the real parent is only
2210 * interested in the completion of group stop. The states
2211 * for the two don't interact with each other. Notify
2212 * separately unless they're gonna be duplicates.
2213 */
2214 do_notify_parent_cldstop(current, true, why);
2215 if (gstop_done && ptrace_reparented(current))
2216 do_notify_parent_cldstop(current, false, why);
2217
2218 /*
2219 * Don't want to allow preemption here, because
2220 * sys_ptrace() needs this task to be inactive.
2221 *
2222 * XXX: implement read_unlock_no_resched().
2223 */
2224 preempt_disable();
2225 read_unlock(&tasklist_lock);
2226 cgroup_enter_frozen();
2227 preempt_enable_no_resched();
2228 freezable_schedule();
2229 cgroup_leave_frozen(true);
2230 } else {
2231 /*
2232 * By the time we got the lock, our tracer went away.
2233 * Don't drop the lock yet, another tracer may come.
2234 *
2235 * If @gstop_done, the ptracer went away between group stop
2236 * completion and here. During detach, it would have set
2237 * JOBCTL_STOP_PENDING on us and we'll re-enter
2238 * TASK_STOPPED in do_signal_stop() on return, so notifying
2239 * the real parent of the group stop completion is enough.
2240 */
2241 if (gstop_done)
2242 do_notify_parent_cldstop(current, false, why);
2243
2244 /* tasklist protects us from ptrace_freeze_traced() */
2245 __set_current_state(TASK_RUNNING);
2246 if (clear_code)
2247 current->exit_code = 0;
2248 read_unlock(&tasklist_lock);
2249 }
2250
2251 /*
2252 * We are back. Now reacquire the siglock before touching
2253 * last_siginfo, so that we are sure to have synchronized with
2254 * any signal-sending on another CPU that wants to examine it.
2255 */
2256 spin_lock_irq(¤t->sighand->siglock);
2257 current->last_siginfo = NULL;
2258
2259 /* LISTENING can be set only during STOP traps, clear it */
2260 current->jobctl &= ~JOBCTL_LISTENING;
2261
2262 /*
2263 * Queued signals ignored us while we were stopped for tracing.
2264 * So check for any that we should take before resuming user mode.
2265 * This sets TIF_SIGPENDING, but never clears it.
2266 */
2267 recalc_sigpending_tsk(current);
2268}
2269
2270static void ptrace_do_notify(int signr, int exit_code, int why)
2271{
2272 kernel_siginfo_t info;
2273
2274 clear_siginfo(&info);
2275 info.si_signo = signr;
2276 info.si_code = exit_code;
2277 info.si_pid = task_pid_vnr(current);
2278 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2279
2280 /* Let the debugger run. */
2281 ptrace_stop(exit_code, why, 1, &info);
2282}
2283
2284void ptrace_notify(int exit_code)
2285{
2286 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2287 if (unlikely(current->task_works))
2288 task_work_run();
2289
2290 spin_lock_irq(¤t->sighand->siglock);
2291 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2292 spin_unlock_irq(¤t->sighand->siglock);
2293}
2294
2295/**
2296 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2297 * @signr: signr causing group stop if initiating
2298 *
2299 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2300 * and participate in it. If already set, participate in the existing
2301 * group stop. If participated in a group stop (and thus slept), %true is
2302 * returned with siglock released.
2303 *
2304 * If ptraced, this function doesn't handle stop itself. Instead,
2305 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2306 * untouched. The caller must ensure that INTERRUPT trap handling takes
2307 * places afterwards.
2308 *
2309 * CONTEXT:
2310 * Must be called with @current->sighand->siglock held, which is released
2311 * on %true return.
2312 *
2313 * RETURNS:
2314 * %false if group stop is already cancelled or ptrace trap is scheduled.
2315 * %true if participated in group stop.
2316 */
2317static bool do_signal_stop(int signr)
2318 __releases(¤t->sighand->siglock)
2319{
2320 struct signal_struct *sig = current->signal;
2321
2322 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2323 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2324 struct task_struct *t;
2325
2326 /* signr will be recorded in task->jobctl for retries */
2327 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2328
2329 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2330 unlikely(signal_group_exit(sig)))
2331 return false;
2332 /*
2333 * There is no group stop already in progress. We must
2334 * initiate one now.
2335 *
2336 * While ptraced, a task may be resumed while group stop is
2337 * still in effect and then receive a stop signal and
2338 * initiate another group stop. This deviates from the
2339 * usual behavior as two consecutive stop signals can't
2340 * cause two group stops when !ptraced. That is why we
2341 * also check !task_is_stopped(t) below.
2342 *
2343 * The condition can be distinguished by testing whether
2344 * SIGNAL_STOP_STOPPED is already set. Don't generate
2345 * group_exit_code in such case.
2346 *
2347 * This is not necessary for SIGNAL_STOP_CONTINUED because
2348 * an intervening stop signal is required to cause two
2349 * continued events regardless of ptrace.
2350 */
2351 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2352 sig->group_exit_code = signr;
2353
2354 sig->group_stop_count = 0;
2355
2356 if (task_set_jobctl_pending(current, signr | gstop))
2357 sig->group_stop_count++;
2358
2359 t = current;
2360 while_each_thread(current, t) {
2361 /*
2362 * Setting state to TASK_STOPPED for a group
2363 * stop is always done with the siglock held,
2364 * so this check has no races.
2365 */
2366 if (!task_is_stopped(t) &&
2367 task_set_jobctl_pending(t, signr | gstop)) {
2368 sig->group_stop_count++;
2369 if (likely(!(t->ptrace & PT_SEIZED)))
2370 signal_wake_up(t, 0);
2371 else
2372 ptrace_trap_notify(t);
2373 }
2374 }
2375 }
2376
2377 if (likely(!current->ptrace)) {
2378 int notify = 0;
2379
2380 /*
2381 * If there are no other threads in the group, or if there
2382 * is a group stop in progress and we are the last to stop,
2383 * report to the parent.
2384 */
2385 if (task_participate_group_stop(current))
2386 notify = CLD_STOPPED;
2387
2388 set_special_state(TASK_STOPPED);
2389 spin_unlock_irq(¤t->sighand->siglock);
2390
2391 /*
2392 * Notify the parent of the group stop completion. Because
2393 * we're not holding either the siglock or tasklist_lock
2394 * here, ptracer may attach inbetween; however, this is for
2395 * group stop and should always be delivered to the real
2396 * parent of the group leader. The new ptracer will get
2397 * its notification when this task transitions into
2398 * TASK_TRACED.
2399 */
2400 if (notify) {
2401 read_lock(&tasklist_lock);
2402 do_notify_parent_cldstop(current, false, notify);
2403 read_unlock(&tasklist_lock);
2404 }
2405
2406 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2407 cgroup_enter_frozen();
2408 freezable_schedule();
2409 return true;
2410 } else {
2411 /*
2412 * While ptraced, group stop is handled by STOP trap.
2413 * Schedule it and let the caller deal with it.
2414 */
2415 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2416 return false;
2417 }
2418}
2419
2420/**
2421 * do_jobctl_trap - take care of ptrace jobctl traps
2422 *
2423 * When PT_SEIZED, it's used for both group stop and explicit
2424 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2425 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2426 * the stop signal; otherwise, %SIGTRAP.
2427 *
2428 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2429 * number as exit_code and no siginfo.
2430 *
2431 * CONTEXT:
2432 * Must be called with @current->sighand->siglock held, which may be
2433 * released and re-acquired before returning with intervening sleep.
2434 */
2435static void do_jobctl_trap(void)
2436{
2437 struct signal_struct *signal = current->signal;
2438 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2439
2440 if (current->ptrace & PT_SEIZED) {
2441 if (!signal->group_stop_count &&
2442 !(signal->flags & SIGNAL_STOP_STOPPED))
2443 signr = SIGTRAP;
2444 WARN_ON_ONCE(!signr);
2445 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2446 CLD_STOPPED);
2447 } else {
2448 WARN_ON_ONCE(!signr);
2449 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2450 current->exit_code = 0;
2451 }
2452}
2453
2454/**
2455 * do_freezer_trap - handle the freezer jobctl trap
2456 *
2457 * Puts the task into frozen state, if only the task is not about to quit.
2458 * In this case it drops JOBCTL_TRAP_FREEZE.
2459 *
2460 * CONTEXT:
2461 * Must be called with @current->sighand->siglock held,
2462 * which is always released before returning.
2463 */
2464static void do_freezer_trap(void)
2465 __releases(¤t->sighand->siglock)
2466{
2467 /*
2468 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2469 * let's make another loop to give it a chance to be handled.
2470 * In any case, we'll return back.
2471 */
2472 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2473 JOBCTL_TRAP_FREEZE) {
2474 spin_unlock_irq(¤t->sighand->siglock);
2475 return;
2476 }
2477
2478 /*
2479 * Now we're sure that there is no pending fatal signal and no
2480 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2481 * immediately (if there is a non-fatal signal pending), and
2482 * put the task into sleep.
2483 */
2484 __set_current_state(TASK_INTERRUPTIBLE);
2485 clear_thread_flag(TIF_SIGPENDING);
2486 spin_unlock_irq(¤t->sighand->siglock);
2487 cgroup_enter_frozen();
2488 freezable_schedule();
2489}
2490
2491static int ptrace_signal(int signr, kernel_siginfo_t *info)
2492{
2493 /*
2494 * We do not check sig_kernel_stop(signr) but set this marker
2495 * unconditionally because we do not know whether debugger will
2496 * change signr. This flag has no meaning unless we are going
2497 * to stop after return from ptrace_stop(). In this case it will
2498 * be checked in do_signal_stop(), we should only stop if it was
2499 * not cleared by SIGCONT while we were sleeping. See also the
2500 * comment in dequeue_signal().
2501 */
2502 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2503 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2504
2505 /* We're back. Did the debugger cancel the sig? */
2506 signr = current->exit_code;
2507 if (signr == 0)
2508 return signr;
2509
2510 current->exit_code = 0;
2511
2512 /*
2513 * Update the siginfo structure if the signal has
2514 * changed. If the debugger wanted something
2515 * specific in the siginfo structure then it should
2516 * have updated *info via PTRACE_SETSIGINFO.
2517 */
2518 if (signr != info->si_signo) {
2519 clear_siginfo(info);
2520 info->si_signo = signr;
2521 info->si_errno = 0;
2522 info->si_code = SI_USER;
2523 rcu_read_lock();
2524 info->si_pid = task_pid_vnr(current->parent);
2525 info->si_uid = from_kuid_munged(current_user_ns(),
2526 task_uid(current->parent));
2527 rcu_read_unlock();
2528 }
2529
2530 /* If the (new) signal is now blocked, requeue it. */
2531 if (sigismember(¤t->blocked, signr)) {
2532 send_signal(signr, info, current, PIDTYPE_PID);
2533 signr = 0;
2534 }
2535
2536 return signr;
2537}
2538
2539static void hide_si_addr_tag_bits(struct ksignal *ksig)
2540{
2541 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2542 case SIL_FAULT:
2543 case SIL_FAULT_TRAPNO:
2544 case SIL_FAULT_MCEERR:
2545 case SIL_FAULT_BNDERR:
2546 case SIL_FAULT_PKUERR:
2547 case SIL_PERF_EVENT:
2548 ksig->info.si_addr = arch_untagged_si_addr(
2549 ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2550 break;
2551 case SIL_KILL:
2552 case SIL_TIMER:
2553 case SIL_POLL:
2554 case SIL_CHLD:
2555 case SIL_RT:
2556 case SIL_SYS:
2557 break;
2558 }
2559}
2560
2561bool get_signal(struct ksignal *ksig)
2562{
2563 struct sighand_struct *sighand = current->sighand;
2564 struct signal_struct *signal = current->signal;
2565 int signr;
2566
2567 if (unlikely(current->task_works))
2568 task_work_run();
2569
2570 /*
2571 * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so
2572 * that the arch handlers don't all have to do it. If we get here
2573 * without TIF_SIGPENDING, just exit after running signal work.
2574 */
2575 if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
2576 if (test_thread_flag(TIF_NOTIFY_SIGNAL))
2577 tracehook_notify_signal();
2578 if (!task_sigpending(current))
2579 return false;
2580 }
2581
2582 if (unlikely(uprobe_deny_signal()))
2583 return false;
2584
2585 /*
2586 * Do this once, we can't return to user-mode if freezing() == T.
2587 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2588 * thus do not need another check after return.
2589 */
2590 try_to_freeze();
2591
2592relock:
2593 spin_lock_irq(&sighand->siglock);
2594
2595 /*
2596 * Every stopped thread goes here after wakeup. Check to see if
2597 * we should notify the parent, prepare_signal(SIGCONT) encodes
2598 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2599 */
2600 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2601 int why;
2602
2603 if (signal->flags & SIGNAL_CLD_CONTINUED)
2604 why = CLD_CONTINUED;
2605 else
2606 why = CLD_STOPPED;
2607
2608 signal->flags &= ~SIGNAL_CLD_MASK;
2609
2610 spin_unlock_irq(&sighand->siglock);
2611
2612 /*
2613 * Notify the parent that we're continuing. This event is
2614 * always per-process and doesn't make whole lot of sense
2615 * for ptracers, who shouldn't consume the state via
2616 * wait(2) either, but, for backward compatibility, notify
2617 * the ptracer of the group leader too unless it's gonna be
2618 * a duplicate.
2619 */
2620 read_lock(&tasklist_lock);
2621 do_notify_parent_cldstop(current, false, why);
2622
2623 if (ptrace_reparented(current->group_leader))
2624 do_notify_parent_cldstop(current->group_leader,
2625 true, why);
2626 read_unlock(&tasklist_lock);
2627
2628 goto relock;
2629 }
2630
2631 /* Has this task already been marked for death? */
2632 if (signal_group_exit(signal)) {
2633 ksig->info.si_signo = signr = SIGKILL;
2634 sigdelset(¤t->pending.signal, SIGKILL);
2635 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2636 &sighand->action[SIGKILL - 1]);
2637 recalc_sigpending();
2638 goto fatal;
2639 }
2640
2641 for (;;) {
2642 struct k_sigaction *ka;
2643
2644 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2645 do_signal_stop(0))
2646 goto relock;
2647
2648 if (unlikely(current->jobctl &
2649 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2650 if (current->jobctl & JOBCTL_TRAP_MASK) {
2651 do_jobctl_trap();
2652 spin_unlock_irq(&sighand->siglock);
2653 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2654 do_freezer_trap();
2655
2656 goto relock;
2657 }
2658
2659 /*
2660 * If the task is leaving the frozen state, let's update
2661 * cgroup counters and reset the frozen bit.
2662 */
2663 if (unlikely(cgroup_task_frozen(current))) {
2664 spin_unlock_irq(&sighand->siglock);
2665 cgroup_leave_frozen(false);
2666 goto relock;
2667 }
2668
2669 /*
2670 * Signals generated by the execution of an instruction
2671 * need to be delivered before any other pending signals
2672 * so that the instruction pointer in the signal stack
2673 * frame points to the faulting instruction.
2674 */
2675 signr = dequeue_synchronous_signal(&ksig->info);
2676 if (!signr)
2677 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2678
2679 if (!signr)
2680 break; /* will return 0 */
2681
2682 if (unlikely(current->ptrace) && signr != SIGKILL) {
2683 signr = ptrace_signal(signr, &ksig->info);
2684 if (!signr)
2685 continue;
2686 }
2687
2688 ka = &sighand->action[signr-1];
2689
2690 /* Trace actually delivered signals. */
2691 trace_signal_deliver(signr, &ksig->info, ka);
2692
2693 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2694 continue;
2695 if (ka->sa.sa_handler != SIG_DFL) {
2696 /* Run the handler. */
2697 ksig->ka = *ka;
2698
2699 if (ka->sa.sa_flags & SA_ONESHOT)
2700 ka->sa.sa_handler = SIG_DFL;
2701
2702 break; /* will return non-zero "signr" value */
2703 }
2704
2705 /*
2706 * Now we are doing the default action for this signal.
2707 */
2708 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2709 continue;
2710
2711 /*
2712 * Global init gets no signals it doesn't want.
2713 * Container-init gets no signals it doesn't want from same
2714 * container.
2715 *
2716 * Note that if global/container-init sees a sig_kernel_only()
2717 * signal here, the signal must have been generated internally
2718 * or must have come from an ancestor namespace. In either
2719 * case, the signal cannot be dropped.
2720 */
2721 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2722 !sig_kernel_only(signr))
2723 continue;
2724
2725 if (sig_kernel_stop(signr)) {
2726 /*
2727 * The default action is to stop all threads in
2728 * the thread group. The job control signals
2729 * do nothing in an orphaned pgrp, but SIGSTOP
2730 * always works. Note that siglock needs to be
2731 * dropped during the call to is_orphaned_pgrp()
2732 * because of lock ordering with tasklist_lock.
2733 * This allows an intervening SIGCONT to be posted.
2734 * We need to check for that and bail out if necessary.
2735 */
2736 if (signr != SIGSTOP) {
2737 spin_unlock_irq(&sighand->siglock);
2738
2739 /* signals can be posted during this window */
2740
2741 if (is_current_pgrp_orphaned())
2742 goto relock;
2743
2744 spin_lock_irq(&sighand->siglock);
2745 }
2746
2747 if (likely(do_signal_stop(ksig->info.si_signo))) {
2748 /* It released the siglock. */
2749 goto relock;
2750 }
2751
2752 /*
2753 * We didn't actually stop, due to a race
2754 * with SIGCONT or something like that.
2755 */
2756 continue;
2757 }
2758
2759 fatal:
2760 spin_unlock_irq(&sighand->siglock);
2761 if (unlikely(cgroup_task_frozen(current)))
2762 cgroup_leave_frozen(true);
2763
2764 /*
2765 * Anything else is fatal, maybe with a core dump.
2766 */
2767 current->flags |= PF_SIGNALED;
2768
2769 if (sig_kernel_coredump(signr)) {
2770 if (print_fatal_signals)
2771 print_fatal_signal(ksig->info.si_signo);
2772 proc_coredump_connector(current);
2773 /*
2774 * If it was able to dump core, this kills all
2775 * other threads in the group and synchronizes with
2776 * their demise. If we lost the race with another
2777 * thread getting here, it set group_exit_code
2778 * first and our do_group_exit call below will use
2779 * that value and ignore the one we pass it.
2780 */
2781 do_coredump(&ksig->info);
2782 }
2783
2784 /*
2785 * PF_IO_WORKER threads will catch and exit on fatal signals
2786 * themselves. They have cleanup that must be performed, so
2787 * we cannot call do_exit() on their behalf.
2788 */
2789 if (current->flags & PF_IO_WORKER)
2790 goto out;
2791
2792 /*
2793 * Death signals, no core dump.
2794 */
2795 do_group_exit(ksig->info.si_signo);
2796 /* NOTREACHED */
2797 }
2798 spin_unlock_irq(&sighand->siglock);
2799out:
2800 ksig->sig = signr;
2801
2802 if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2803 hide_si_addr_tag_bits(ksig);
2804
2805 return ksig->sig > 0;
2806}
2807
2808/**
2809 * signal_delivered -
2810 * @ksig: kernel signal struct
2811 * @stepping: nonzero if debugger single-step or block-step in use
2812 *
2813 * This function should be called when a signal has successfully been
2814 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2815 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2816 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2817 */
2818static void signal_delivered(struct ksignal *ksig, int stepping)
2819{
2820 sigset_t blocked;
2821
2822 /* A signal was successfully delivered, and the
2823 saved sigmask was stored on the signal frame,
2824 and will be restored by sigreturn. So we can
2825 simply clear the restore sigmask flag. */
2826 clear_restore_sigmask();
2827
2828 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2829 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2830 sigaddset(&blocked, ksig->sig);
2831 set_current_blocked(&blocked);
2832 if (current->sas_ss_flags & SS_AUTODISARM)
2833 sas_ss_reset(current);
2834 tracehook_signal_handler(stepping);
2835}
2836
2837void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2838{
2839 if (failed)
2840 force_sigsegv(ksig->sig);
2841 else
2842 signal_delivered(ksig, stepping);
2843}
2844
2845/*
2846 * It could be that complete_signal() picked us to notify about the
2847 * group-wide signal. Other threads should be notified now to take
2848 * the shared signals in @which since we will not.
2849 */
2850static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2851{
2852 sigset_t retarget;
2853 struct task_struct *t;
2854
2855 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2856 if (sigisemptyset(&retarget))
2857 return;
2858
2859 t = tsk;
2860 while_each_thread(tsk, t) {
2861 if (t->flags & PF_EXITING)
2862 continue;
2863
2864 if (!has_pending_signals(&retarget, &t->blocked))
2865 continue;
2866 /* Remove the signals this thread can handle. */
2867 sigandsets(&retarget, &retarget, &t->blocked);
2868
2869 if (!task_sigpending(t))
2870 signal_wake_up(t, 0);
2871
2872 if (sigisemptyset(&retarget))
2873 break;
2874 }
2875}
2876
2877void exit_signals(struct task_struct *tsk)
2878{
2879 int group_stop = 0;
2880 sigset_t unblocked;
2881
2882 /*
2883 * @tsk is about to have PF_EXITING set - lock out users which
2884 * expect stable threadgroup.
2885 */
2886 cgroup_threadgroup_change_begin(tsk);
2887
2888 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2889 tsk->flags |= PF_EXITING;
2890 cgroup_threadgroup_change_end(tsk);
2891 return;
2892 }
2893
2894 spin_lock_irq(&tsk->sighand->siglock);
2895 /*
2896 * From now this task is not visible for group-wide signals,
2897 * see wants_signal(), do_signal_stop().
2898 */
2899 tsk->flags |= PF_EXITING;
2900
2901 cgroup_threadgroup_change_end(tsk);
2902
2903 if (!task_sigpending(tsk))
2904 goto out;
2905
2906 unblocked = tsk->blocked;
2907 signotset(&unblocked);
2908 retarget_shared_pending(tsk, &unblocked);
2909
2910 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2911 task_participate_group_stop(tsk))
2912 group_stop = CLD_STOPPED;
2913out:
2914 spin_unlock_irq(&tsk->sighand->siglock);
2915
2916 /*
2917 * If group stop has completed, deliver the notification. This
2918 * should always go to the real parent of the group leader.
2919 */
2920 if (unlikely(group_stop)) {
2921 read_lock(&tasklist_lock);
2922 do_notify_parent_cldstop(tsk, false, group_stop);
2923 read_unlock(&tasklist_lock);
2924 }
2925}
2926
2927/*
2928 * System call entry points.
2929 */
2930
2931/**
2932 * sys_restart_syscall - restart a system call
2933 */
2934SYSCALL_DEFINE0(restart_syscall)
2935{
2936 struct restart_block *restart = ¤t->restart_block;
2937 return restart->fn(restart);
2938}
2939
2940long do_no_restart_syscall(struct restart_block *param)
2941{
2942 return -EINTR;
2943}
2944
2945static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2946{
2947 if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
2948 sigset_t newblocked;
2949 /* A set of now blocked but previously unblocked signals. */
2950 sigandnsets(&newblocked, newset, ¤t->blocked);
2951 retarget_shared_pending(tsk, &newblocked);
2952 }
2953 tsk->blocked = *newset;
2954 recalc_sigpending();
2955}
2956
2957/**
2958 * set_current_blocked - change current->blocked mask
2959 * @newset: new mask
2960 *
2961 * It is wrong to change ->blocked directly, this helper should be used
2962 * to ensure the process can't miss a shared signal we are going to block.
2963 */
2964void set_current_blocked(sigset_t *newset)
2965{
2966 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2967 __set_current_blocked(newset);
2968}
2969
2970void __set_current_blocked(const sigset_t *newset)
2971{
2972 struct task_struct *tsk = current;
2973
2974 /*
2975 * In case the signal mask hasn't changed, there is nothing we need
2976 * to do. The current->blocked shouldn't be modified by other task.
2977 */
2978 if (sigequalsets(&tsk->blocked, newset))
2979 return;
2980
2981 spin_lock_irq(&tsk->sighand->siglock);
2982 __set_task_blocked(tsk, newset);
2983 spin_unlock_irq(&tsk->sighand->siglock);
2984}
2985
2986/*
2987 * This is also useful for kernel threads that want to temporarily
2988 * (or permanently) block certain signals.
2989 *
2990 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2991 * interface happily blocks "unblockable" signals like SIGKILL
2992 * and friends.
2993 */
2994int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2995{
2996 struct task_struct *tsk = current;
2997 sigset_t newset;
2998
2999 /* Lockless, only current can change ->blocked, never from irq */
3000 if (oldset)
3001 *oldset = tsk->blocked;
3002
3003 switch (how) {
3004 case SIG_BLOCK:
3005 sigorsets(&newset, &tsk->blocked, set);
3006 break;
3007 case SIG_UNBLOCK:
3008 sigandnsets(&newset, &tsk->blocked, set);
3009 break;
3010 case SIG_SETMASK:
3011 newset = *set;
3012 break;
3013 default:
3014 return -EINVAL;
3015 }
3016
3017 __set_current_blocked(&newset);
3018 return 0;
3019}
3020EXPORT_SYMBOL(sigprocmask);
3021
3022/*
3023 * The api helps set app-provided sigmasks.
3024 *
3025 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3026 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3027 *
3028 * Note that it does set_restore_sigmask() in advance, so it must be always
3029 * paired with restore_saved_sigmask_unless() before return from syscall.
3030 */
3031int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3032{
3033 sigset_t kmask;
3034
3035 if (!umask)
3036 return 0;
3037 if (sigsetsize != sizeof(sigset_t))
3038 return -EINVAL;
3039 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3040 return -EFAULT;
3041
3042 set_restore_sigmask();
3043 current->saved_sigmask = current->blocked;
3044 set_current_blocked(&kmask);
3045
3046 return 0;
3047}
3048
3049#ifdef CONFIG_COMPAT
3050int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3051 size_t sigsetsize)
3052{
3053 sigset_t kmask;
3054
3055 if (!umask)
3056 return 0;
3057 if (sigsetsize != sizeof(compat_sigset_t))
3058 return -EINVAL;
3059 if (get_compat_sigset(&kmask, umask))
3060 return -EFAULT;
3061
3062 set_restore_sigmask();
3063 current->saved_sigmask = current->blocked;
3064 set_current_blocked(&kmask);
3065
3066 return 0;
3067}
3068#endif
3069
3070/**
3071 * sys_rt_sigprocmask - change the list of currently blocked signals
3072 * @how: whether to add, remove, or set signals
3073 * @nset: stores pending signals
3074 * @oset: previous value of signal mask if non-null
3075 * @sigsetsize: size of sigset_t type
3076 */
3077SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3078 sigset_t __user *, oset, size_t, sigsetsize)
3079{
3080 sigset_t old_set, new_set;
3081 int error;
3082
3083 /* XXX: Don't preclude handling different sized sigset_t's. */
3084 if (sigsetsize != sizeof(sigset_t))
3085 return -EINVAL;
3086
3087 old_set = current->blocked;
3088
3089 if (nset) {
3090 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3091 return -EFAULT;
3092 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3093
3094 error = sigprocmask(how, &new_set, NULL);
3095 if (error)
3096 return error;
3097 }
3098
3099 if (oset) {
3100 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3101 return -EFAULT;
3102 }
3103
3104 return 0;
3105}
3106
3107#ifdef CONFIG_COMPAT
3108COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3109 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3110{
3111 sigset_t old_set = current->blocked;
3112
3113 /* XXX: Don't preclude handling different sized sigset_t's. */
3114 if (sigsetsize != sizeof(sigset_t))
3115 return -EINVAL;
3116
3117 if (nset) {
3118 sigset_t new_set;
3119 int error;
3120 if (get_compat_sigset(&new_set, nset))
3121 return -EFAULT;
3122 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3123
3124 error = sigprocmask(how, &new_set, NULL);
3125 if (error)
3126 return error;
3127 }
3128 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3129}
3130#endif
3131
3132static void do_sigpending(sigset_t *set)
3133{
3134 spin_lock_irq(¤t->sighand->siglock);
3135 sigorsets(set, ¤t->pending.signal,
3136 ¤t->signal->shared_pending.signal);
3137 spin_unlock_irq(¤t->sighand->siglock);
3138
3139 /* Outside the lock because only this thread touches it. */
3140 sigandsets(set, ¤t->blocked, set);
3141}
3142
3143/**
3144 * sys_rt_sigpending - examine a pending signal that has been raised
3145 * while blocked
3146 * @uset: stores pending signals
3147 * @sigsetsize: size of sigset_t type or larger
3148 */
3149SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3150{
3151 sigset_t set;
3152
3153 if (sigsetsize > sizeof(*uset))
3154 return -EINVAL;
3155
3156 do_sigpending(&set);
3157
3158 if (copy_to_user(uset, &set, sigsetsize))
3159 return -EFAULT;
3160
3161 return 0;
3162}
3163
3164#ifdef CONFIG_COMPAT
3165COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3166 compat_size_t, sigsetsize)
3167{
3168 sigset_t set;
3169
3170 if (sigsetsize > sizeof(*uset))
3171 return -EINVAL;
3172
3173 do_sigpending(&set);
3174
3175 return put_compat_sigset(uset, &set, sigsetsize);
3176}
3177#endif
3178
3179static const struct {
3180 unsigned char limit, layout;
3181} sig_sicodes[] = {
3182 [SIGILL] = { NSIGILL, SIL_FAULT },
3183 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3184 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3185 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3186 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3187#if defined(SIGEMT)
3188 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3189#endif
3190 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3191 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3192 [SIGSYS] = { NSIGSYS, SIL_SYS },
3193};
3194
3195static bool known_siginfo_layout(unsigned sig, int si_code)
3196{
3197 if (si_code == SI_KERNEL)
3198 return true;
3199 else if ((si_code > SI_USER)) {
3200 if (sig_specific_sicodes(sig)) {
3201 if (si_code <= sig_sicodes[sig].limit)
3202 return true;
3203 }
3204 else if (si_code <= NSIGPOLL)
3205 return true;
3206 }
3207 else if (si_code >= SI_DETHREAD)
3208 return true;
3209 else if (si_code == SI_ASYNCNL)
3210 return true;
3211 return false;
3212}
3213
3214enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3215{
3216 enum siginfo_layout layout = SIL_KILL;
3217 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3218 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3219 (si_code <= sig_sicodes[sig].limit)) {
3220 layout = sig_sicodes[sig].layout;
3221 /* Handle the exceptions */
3222 if ((sig == SIGBUS) &&
3223 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3224 layout = SIL_FAULT_MCEERR;
3225 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3226 layout = SIL_FAULT_BNDERR;
3227#ifdef SEGV_PKUERR
3228 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3229 layout = SIL_FAULT_PKUERR;
3230#endif
3231 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3232 layout = SIL_PERF_EVENT;
3233#ifdef __ARCH_SI_TRAPNO
3234 else if (layout == SIL_FAULT)
3235 layout = SIL_FAULT_TRAPNO;
3236#endif
3237 }
3238 else if (si_code <= NSIGPOLL)
3239 layout = SIL_POLL;
3240 } else {
3241 if (si_code == SI_TIMER)
3242 layout = SIL_TIMER;
3243 else if (si_code == SI_SIGIO)
3244 layout = SIL_POLL;
3245 else if (si_code < 0)
3246 layout = SIL_RT;
3247 }
3248 return layout;
3249}
3250
3251static inline char __user *si_expansion(const siginfo_t __user *info)
3252{
3253 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3254}
3255
3256int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3257{
3258 char __user *expansion = si_expansion(to);
3259 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3260 return -EFAULT;
3261 if (clear_user(expansion, SI_EXPANSION_SIZE))
3262 return -EFAULT;
3263 return 0;
3264}
3265
3266static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3267 const siginfo_t __user *from)
3268{
3269 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3270 char __user *expansion = si_expansion(from);
3271 char buf[SI_EXPANSION_SIZE];
3272 int i;
3273 /*
3274 * An unknown si_code might need more than
3275 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3276 * extra bytes are 0. This guarantees copy_siginfo_to_user
3277 * will return this data to userspace exactly.
3278 */
3279 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3280 return -EFAULT;
3281 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3282 if (buf[i] != 0)
3283 return -E2BIG;
3284 }
3285 }
3286 return 0;
3287}
3288
3289static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3290 const siginfo_t __user *from)
3291{
3292 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3293 return -EFAULT;
3294 to->si_signo = signo;
3295 return post_copy_siginfo_from_user(to, from);
3296}
3297
3298int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3299{
3300 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3301 return -EFAULT;
3302 return post_copy_siginfo_from_user(to, from);
3303}
3304
3305#ifdef CONFIG_COMPAT
3306/**
3307 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3308 * @to: compat siginfo destination
3309 * @from: kernel siginfo source
3310 *
3311 * Note: This function does not work properly for the SIGCHLD on x32, but
3312 * fortunately it doesn't have to. The only valid callers for this function are
3313 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3314 * The latter does not care because SIGCHLD will never cause a coredump.
3315 */
3316void copy_siginfo_to_external32(struct compat_siginfo *to,
3317 const struct kernel_siginfo *from)
3318{
3319 memset(to, 0, sizeof(*to));
3320
3321 to->si_signo = from->si_signo;
3322 to->si_errno = from->si_errno;
3323 to->si_code = from->si_code;
3324 switch(siginfo_layout(from->si_signo, from->si_code)) {
3325 case SIL_KILL:
3326 to->si_pid = from->si_pid;
3327 to->si_uid = from->si_uid;
3328 break;
3329 case SIL_TIMER:
3330 to->si_tid = from->si_tid;
3331 to->si_overrun = from->si_overrun;
3332 to->si_int = from->si_int;
3333 break;
3334 case SIL_POLL:
3335 to->si_band = from->si_band;
3336 to->si_fd = from->si_fd;
3337 break;
3338 case SIL_FAULT:
3339 to->si_addr = ptr_to_compat(from->si_addr);
3340 break;
3341 case SIL_FAULT_TRAPNO:
3342 to->si_addr = ptr_to_compat(from->si_addr);
3343 to->si_trapno = from->si_trapno;
3344 break;
3345 case SIL_FAULT_MCEERR:
3346 to->si_addr = ptr_to_compat(from->si_addr);
3347 to->si_addr_lsb = from->si_addr_lsb;
3348 break;
3349 case SIL_FAULT_BNDERR:
3350 to->si_addr = ptr_to_compat(from->si_addr);
3351 to->si_lower = ptr_to_compat(from->si_lower);
3352 to->si_upper = ptr_to_compat(from->si_upper);
3353 break;
3354 case SIL_FAULT_PKUERR:
3355 to->si_addr = ptr_to_compat(from->si_addr);
3356 to->si_pkey = from->si_pkey;
3357 break;
3358 case SIL_PERF_EVENT:
3359 to->si_addr = ptr_to_compat(from->si_addr);
3360 to->si_perf_data = from->si_perf_data;
3361 to->si_perf_type = from->si_perf_type;
3362 break;
3363 case SIL_CHLD:
3364 to->si_pid = from->si_pid;
3365 to->si_uid = from->si_uid;
3366 to->si_status = from->si_status;
3367 to->si_utime = from->si_utime;
3368 to->si_stime = from->si_stime;
3369 break;
3370 case SIL_RT:
3371 to->si_pid = from->si_pid;
3372 to->si_uid = from->si_uid;
3373 to->si_int = from->si_int;
3374 break;
3375 case SIL_SYS:
3376 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3377 to->si_syscall = from->si_syscall;
3378 to->si_arch = from->si_arch;
3379 break;
3380 }
3381}
3382
3383int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3384 const struct kernel_siginfo *from)
3385{
3386 struct compat_siginfo new;
3387
3388 copy_siginfo_to_external32(&new, from);
3389 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3390 return -EFAULT;
3391 return 0;
3392}
3393
3394static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3395 const struct compat_siginfo *from)
3396{
3397 clear_siginfo(to);
3398 to->si_signo = from->si_signo;
3399 to->si_errno = from->si_errno;
3400 to->si_code = from->si_code;
3401 switch(siginfo_layout(from->si_signo, from->si_code)) {
3402 case SIL_KILL:
3403 to->si_pid = from->si_pid;
3404 to->si_uid = from->si_uid;
3405 break;
3406 case SIL_TIMER:
3407 to->si_tid = from->si_tid;
3408 to->si_overrun = from->si_overrun;
3409 to->si_int = from->si_int;
3410 break;
3411 case SIL_POLL:
3412 to->si_band = from->si_band;
3413 to->si_fd = from->si_fd;
3414 break;
3415 case SIL_FAULT:
3416 to->si_addr = compat_ptr(from->si_addr);
3417 break;
3418 case SIL_FAULT_TRAPNO:
3419 to->si_addr = compat_ptr(from->si_addr);
3420 to->si_trapno = from->si_trapno;
3421 break;
3422 case SIL_FAULT_MCEERR:
3423 to->si_addr = compat_ptr(from->si_addr);
3424 to->si_addr_lsb = from->si_addr_lsb;
3425 break;
3426 case SIL_FAULT_BNDERR:
3427 to->si_addr = compat_ptr(from->si_addr);
3428 to->si_lower = compat_ptr(from->si_lower);
3429 to->si_upper = compat_ptr(from->si_upper);
3430 break;
3431 case SIL_FAULT_PKUERR:
3432 to->si_addr = compat_ptr(from->si_addr);
3433 to->si_pkey = from->si_pkey;
3434 break;
3435 case SIL_PERF_EVENT:
3436 to->si_addr = compat_ptr(from->si_addr);
3437 to->si_perf_data = from->si_perf_data;
3438 to->si_perf_type = from->si_perf_type;
3439 break;
3440 case SIL_CHLD:
3441 to->si_pid = from->si_pid;
3442 to->si_uid = from->si_uid;
3443 to->si_status = from->si_status;
3444#ifdef CONFIG_X86_X32_ABI
3445 if (in_x32_syscall()) {
3446 to->si_utime = from->_sifields._sigchld_x32._utime;
3447 to->si_stime = from->_sifields._sigchld_x32._stime;
3448 } else
3449#endif
3450 {
3451 to->si_utime = from->si_utime;
3452 to->si_stime = from->si_stime;
3453 }
3454 break;
3455 case SIL_RT:
3456 to->si_pid = from->si_pid;
3457 to->si_uid = from->si_uid;
3458 to->si_int = from->si_int;
3459 break;
3460 case SIL_SYS:
3461 to->si_call_addr = compat_ptr(from->si_call_addr);
3462 to->si_syscall = from->si_syscall;
3463 to->si_arch = from->si_arch;
3464 break;
3465 }
3466 return 0;
3467}
3468
3469static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3470 const struct compat_siginfo __user *ufrom)
3471{
3472 struct compat_siginfo from;
3473
3474 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3475 return -EFAULT;
3476
3477 from.si_signo = signo;
3478 return post_copy_siginfo_from_user32(to, &from);
3479}
3480
3481int copy_siginfo_from_user32(struct kernel_siginfo *to,
3482 const struct compat_siginfo __user *ufrom)
3483{
3484 struct compat_siginfo from;
3485
3486 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3487 return -EFAULT;
3488
3489 return post_copy_siginfo_from_user32(to, &from);
3490}
3491#endif /* CONFIG_COMPAT */
3492
3493/**
3494 * do_sigtimedwait - wait for queued signals specified in @which
3495 * @which: queued signals to wait for
3496 * @info: if non-null, the signal's siginfo is returned here
3497 * @ts: upper bound on process time suspension
3498 */
3499static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3500 const struct timespec64 *ts)
3501{
3502 ktime_t *to = NULL, timeout = KTIME_MAX;
3503 struct task_struct *tsk = current;
3504 sigset_t mask = *which;
3505 int sig, ret = 0;
3506
3507 if (ts) {
3508 if (!timespec64_valid(ts))
3509 return -EINVAL;
3510 timeout = timespec64_to_ktime(*ts);
3511 to = &timeout;
3512 }
3513
3514 /*
3515 * Invert the set of allowed signals to get those we want to block.
3516 */
3517 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3518 signotset(&mask);
3519
3520 spin_lock_irq(&tsk->sighand->siglock);
3521 sig = dequeue_signal(tsk, &mask, info);
3522 if (!sig && timeout) {
3523 /*
3524 * None ready, temporarily unblock those we're interested
3525 * while we are sleeping in so that we'll be awakened when
3526 * they arrive. Unblocking is always fine, we can avoid
3527 * set_current_blocked().
3528 */
3529 tsk->real_blocked = tsk->blocked;
3530 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3531 recalc_sigpending();
3532 spin_unlock_irq(&tsk->sighand->siglock);
3533
3534 __set_current_state(TASK_INTERRUPTIBLE);
3535 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3536 HRTIMER_MODE_REL);
3537 spin_lock_irq(&tsk->sighand->siglock);
3538 __set_task_blocked(tsk, &tsk->real_blocked);
3539 sigemptyset(&tsk->real_blocked);
3540 sig = dequeue_signal(tsk, &mask, info);
3541 }
3542 spin_unlock_irq(&tsk->sighand->siglock);
3543
3544 if (sig)
3545 return sig;
3546 return ret ? -EINTR : -EAGAIN;
3547}
3548
3549/**
3550 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3551 * in @uthese
3552 * @uthese: queued signals to wait for
3553 * @uinfo: if non-null, the signal's siginfo is returned here
3554 * @uts: upper bound on process time suspension
3555 * @sigsetsize: size of sigset_t type
3556 */
3557SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3558 siginfo_t __user *, uinfo,
3559 const struct __kernel_timespec __user *, uts,
3560 size_t, sigsetsize)
3561{
3562 sigset_t these;
3563 struct timespec64 ts;
3564 kernel_siginfo_t info;
3565 int ret;
3566
3567 /* XXX: Don't preclude handling different sized sigset_t's. */
3568 if (sigsetsize != sizeof(sigset_t))
3569 return -EINVAL;
3570
3571 if (copy_from_user(&these, uthese, sizeof(these)))
3572 return -EFAULT;
3573
3574 if (uts) {
3575 if (get_timespec64(&ts, uts))
3576 return -EFAULT;
3577 }
3578
3579 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3580
3581 if (ret > 0 && uinfo) {
3582 if (copy_siginfo_to_user(uinfo, &info))
3583 ret = -EFAULT;
3584 }
3585
3586 return ret;
3587}
3588
3589#ifdef CONFIG_COMPAT_32BIT_TIME
3590SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3591 siginfo_t __user *, uinfo,
3592 const struct old_timespec32 __user *, uts,
3593 size_t, sigsetsize)
3594{
3595 sigset_t these;
3596 struct timespec64 ts;
3597 kernel_siginfo_t info;
3598 int ret;
3599
3600 if (sigsetsize != sizeof(sigset_t))
3601 return -EINVAL;
3602
3603 if (copy_from_user(&these, uthese, sizeof(these)))
3604 return -EFAULT;
3605
3606 if (uts) {
3607 if (get_old_timespec32(&ts, uts))
3608 return -EFAULT;
3609 }
3610
3611 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3612
3613 if (ret > 0 && uinfo) {
3614 if (copy_siginfo_to_user(uinfo, &info))
3615 ret = -EFAULT;
3616 }
3617
3618 return ret;
3619}
3620#endif
3621
3622#ifdef CONFIG_COMPAT
3623COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3624 struct compat_siginfo __user *, uinfo,
3625 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3626{
3627 sigset_t s;
3628 struct timespec64 t;
3629 kernel_siginfo_t info;
3630 long ret;
3631
3632 if (sigsetsize != sizeof(sigset_t))
3633 return -EINVAL;
3634
3635 if (get_compat_sigset(&s, uthese))
3636 return -EFAULT;
3637
3638 if (uts) {
3639 if (get_timespec64(&t, uts))
3640 return -EFAULT;
3641 }
3642
3643 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3644
3645 if (ret > 0 && uinfo) {
3646 if (copy_siginfo_to_user32(uinfo, &info))
3647 ret = -EFAULT;
3648 }
3649
3650 return ret;
3651}
3652
3653#ifdef CONFIG_COMPAT_32BIT_TIME
3654COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3655 struct compat_siginfo __user *, uinfo,
3656 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3657{
3658 sigset_t s;
3659 struct timespec64 t;
3660 kernel_siginfo_t info;
3661 long ret;
3662
3663 if (sigsetsize != sizeof(sigset_t))
3664 return -EINVAL;
3665
3666 if (get_compat_sigset(&s, uthese))
3667 return -EFAULT;
3668
3669 if (uts) {
3670 if (get_old_timespec32(&t, uts))
3671 return -EFAULT;
3672 }
3673
3674 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3675
3676 if (ret > 0 && uinfo) {
3677 if (copy_siginfo_to_user32(uinfo, &info))
3678 ret = -EFAULT;
3679 }
3680
3681 return ret;
3682}
3683#endif
3684#endif
3685
3686static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3687{
3688 clear_siginfo(info);
3689 info->si_signo = sig;
3690 info->si_errno = 0;
3691 info->si_code = SI_USER;
3692 info->si_pid = task_tgid_vnr(current);
3693 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3694}
3695
3696/**
3697 * sys_kill - send a signal to a process
3698 * @pid: the PID of the process
3699 * @sig: signal to be sent
3700 */
3701SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3702{
3703 struct kernel_siginfo info;
3704
3705 prepare_kill_siginfo(sig, &info);
3706
3707 return kill_something_info(sig, &info, pid);
3708}
3709
3710/*
3711 * Verify that the signaler and signalee either are in the same pid namespace
3712 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3713 * namespace.
3714 */
3715static bool access_pidfd_pidns(struct pid *pid)
3716{
3717 struct pid_namespace *active = task_active_pid_ns(current);
3718 struct pid_namespace *p = ns_of_pid(pid);
3719
3720 for (;;) {
3721 if (!p)
3722 return false;
3723 if (p == active)
3724 break;
3725 p = p->parent;
3726 }
3727
3728 return true;
3729}
3730
3731static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3732 siginfo_t __user *info)
3733{
3734#ifdef CONFIG_COMPAT
3735 /*
3736 * Avoid hooking up compat syscalls and instead handle necessary
3737 * conversions here. Note, this is a stop-gap measure and should not be
3738 * considered a generic solution.
3739 */
3740 if (in_compat_syscall())
3741 return copy_siginfo_from_user32(
3742 kinfo, (struct compat_siginfo __user *)info);
3743#endif
3744 return copy_siginfo_from_user(kinfo, info);
3745}
3746
3747static struct pid *pidfd_to_pid(const struct file *file)
3748{
3749 struct pid *pid;
3750
3751 pid = pidfd_pid(file);
3752 if (!IS_ERR(pid))
3753 return pid;
3754
3755 return tgid_pidfd_to_pid(file);
3756}
3757
3758/**
3759 * sys_pidfd_send_signal - Signal a process through a pidfd
3760 * @pidfd: file descriptor of the process
3761 * @sig: signal to send
3762 * @info: signal info
3763 * @flags: future flags
3764 *
3765 * The syscall currently only signals via PIDTYPE_PID which covers
3766 * kill(<positive-pid>, <signal>. It does not signal threads or process
3767 * groups.
3768 * In order to extend the syscall to threads and process groups the @flags
3769 * argument should be used. In essence, the @flags argument will determine
3770 * what is signaled and not the file descriptor itself. Put in other words,
3771 * grouping is a property of the flags argument not a property of the file
3772 * descriptor.
3773 *
3774 * Return: 0 on success, negative errno on failure
3775 */
3776SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3777 siginfo_t __user *, info, unsigned int, flags)
3778{
3779 int ret;
3780 struct fd f;
3781 struct pid *pid;
3782 kernel_siginfo_t kinfo;
3783
3784 /* Enforce flags be set to 0 until we add an extension. */
3785 if (flags)
3786 return -EINVAL;
3787
3788 f = fdget(pidfd);
3789 if (!f.file)
3790 return -EBADF;
3791
3792 /* Is this a pidfd? */
3793 pid = pidfd_to_pid(f.file);
3794 if (IS_ERR(pid)) {
3795 ret = PTR_ERR(pid);
3796 goto err;
3797 }
3798
3799 ret = -EINVAL;
3800 if (!access_pidfd_pidns(pid))
3801 goto err;
3802
3803 if (info) {
3804 ret = copy_siginfo_from_user_any(&kinfo, info);
3805 if (unlikely(ret))
3806 goto err;
3807
3808 ret = -EINVAL;
3809 if (unlikely(sig != kinfo.si_signo))
3810 goto err;
3811
3812 /* Only allow sending arbitrary signals to yourself. */
3813 ret = -EPERM;
3814 if ((task_pid(current) != pid) &&
3815 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3816 goto err;
3817 } else {
3818 prepare_kill_siginfo(sig, &kinfo);
3819 }
3820
3821 ret = kill_pid_info(sig, &kinfo, pid);
3822
3823err:
3824 fdput(f);
3825 return ret;
3826}
3827
3828static int
3829do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3830{
3831 struct task_struct *p;
3832 int error = -ESRCH;
3833
3834 rcu_read_lock();
3835 p = find_task_by_vpid(pid);
3836 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3837 error = check_kill_permission(sig, info, p);
3838 /*
3839 * The null signal is a permissions and process existence
3840 * probe. No signal is actually delivered.
3841 */
3842 if (!error && sig) {
3843 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3844 /*
3845 * If lock_task_sighand() failed we pretend the task
3846 * dies after receiving the signal. The window is tiny,
3847 * and the signal is private anyway.
3848 */
3849 if (unlikely(error == -ESRCH))
3850 error = 0;
3851 }
3852 }
3853 rcu_read_unlock();
3854
3855 return error;
3856}
3857
3858static int do_tkill(pid_t tgid, pid_t pid, int sig)
3859{
3860 struct kernel_siginfo info;
3861
3862 clear_siginfo(&info);
3863 info.si_signo = sig;
3864 info.si_errno = 0;
3865 info.si_code = SI_TKILL;
3866 info.si_pid = task_tgid_vnr(current);
3867 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3868
3869 return do_send_specific(tgid, pid, sig, &info);
3870}
3871
3872/**
3873 * sys_tgkill - send signal to one specific thread
3874 * @tgid: the thread group ID of the thread
3875 * @pid: the PID of the thread
3876 * @sig: signal to be sent
3877 *
3878 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3879 * exists but it's not belonging to the target process anymore. This
3880 * method solves the problem of threads exiting and PIDs getting reused.
3881 */
3882SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3883{
3884 /* This is only valid for single tasks */
3885 if (pid <= 0 || tgid <= 0)
3886 return -EINVAL;
3887
3888 return do_tkill(tgid, pid, sig);
3889}
3890
3891/**
3892 * sys_tkill - send signal to one specific task
3893 * @pid: the PID of the task
3894 * @sig: signal to be sent
3895 *
3896 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3897 */
3898SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3899{
3900 /* This is only valid for single tasks */
3901 if (pid <= 0)
3902 return -EINVAL;
3903
3904 return do_tkill(0, pid, sig);
3905}
3906
3907static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3908{
3909 /* Not even root can pretend to send signals from the kernel.
3910 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3911 */
3912 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3913 (task_pid_vnr(current) != pid))
3914 return -EPERM;
3915
3916 /* POSIX.1b doesn't mention process groups. */
3917 return kill_proc_info(sig, info, pid);
3918}
3919
3920/**
3921 * sys_rt_sigqueueinfo - send signal information to a signal
3922 * @pid: the PID of the thread
3923 * @sig: signal to be sent
3924 * @uinfo: signal info to be sent
3925 */
3926SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3927 siginfo_t __user *, uinfo)
3928{
3929 kernel_siginfo_t info;
3930 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3931 if (unlikely(ret))
3932 return ret;
3933 return do_rt_sigqueueinfo(pid, sig, &info);
3934}
3935
3936#ifdef CONFIG_COMPAT
3937COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3938 compat_pid_t, pid,
3939 int, sig,
3940 struct compat_siginfo __user *, uinfo)
3941{
3942 kernel_siginfo_t info;
3943 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3944 if (unlikely(ret))
3945 return ret;
3946 return do_rt_sigqueueinfo(pid, sig, &info);
3947}
3948#endif
3949
3950static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
3951{
3952 /* This is only valid for single tasks */
3953 if (pid <= 0 || tgid <= 0)
3954 return -EINVAL;
3955
3956 /* Not even root can pretend to send signals from the kernel.
3957 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3958 */
3959 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3960 (task_pid_vnr(current) != pid))
3961 return -EPERM;
3962
3963 return do_send_specific(tgid, pid, sig, info);
3964}
3965
3966SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3967 siginfo_t __user *, uinfo)
3968{
3969 kernel_siginfo_t info;
3970 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3971 if (unlikely(ret))
3972 return ret;
3973 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3974}
3975
3976#ifdef CONFIG_COMPAT
3977COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3978 compat_pid_t, tgid,
3979 compat_pid_t, pid,
3980 int, sig,
3981 struct compat_siginfo __user *, uinfo)
3982{
3983 kernel_siginfo_t info;
3984 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3985 if (unlikely(ret))
3986 return ret;
3987 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3988}
3989#endif
3990
3991/*
3992 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3993 */
3994void kernel_sigaction(int sig, __sighandler_t action)
3995{
3996 spin_lock_irq(¤t->sighand->siglock);
3997 current->sighand->action[sig - 1].sa.sa_handler = action;
3998 if (action == SIG_IGN) {
3999 sigset_t mask;
4000
4001 sigemptyset(&mask);
4002 sigaddset(&mask, sig);
4003
4004 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4005 flush_sigqueue_mask(&mask, ¤t->pending);
4006 recalc_sigpending();
4007 }
4008 spin_unlock_irq(¤t->sighand->siglock);
4009}
4010EXPORT_SYMBOL(kernel_sigaction);
4011
4012void __weak sigaction_compat_abi(struct k_sigaction *act,
4013 struct k_sigaction *oact)
4014{
4015}
4016
4017int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4018{
4019 struct task_struct *p = current, *t;
4020 struct k_sigaction *k;
4021 sigset_t mask;
4022
4023 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4024 return -EINVAL;
4025
4026 k = &p->sighand->action[sig-1];
4027
4028 spin_lock_irq(&p->sighand->siglock);
4029 if (oact)
4030 *oact = *k;
4031
4032 /*
4033 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4034 * e.g. by having an architecture use the bit in their uapi.
4035 */
4036 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4037
4038 /*
4039 * Clear unknown flag bits in order to allow userspace to detect missing
4040 * support for flag bits and to allow the kernel to use non-uapi bits
4041 * internally.
4042 */
4043 if (act)
4044 act->sa.sa_flags &= UAPI_SA_FLAGS;
4045 if (oact)
4046 oact->sa.sa_flags &= UAPI_SA_FLAGS;
4047
4048 sigaction_compat_abi(act, oact);
4049
4050 if (act) {
4051 sigdelsetmask(&act->sa.sa_mask,
4052 sigmask(SIGKILL) | sigmask(SIGSTOP));
4053 *k = *act;
4054 /*
4055 * POSIX 3.3.1.3:
4056 * "Setting a signal action to SIG_IGN for a signal that is
4057 * pending shall cause the pending signal to be discarded,
4058 * whether or not it is blocked."
4059 *
4060 * "Setting a signal action to SIG_DFL for a signal that is
4061 * pending and whose default action is to ignore the signal
4062 * (for example, SIGCHLD), shall cause the pending signal to
4063 * be discarded, whether or not it is blocked"
4064 */
4065 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4066 sigemptyset(&mask);
4067 sigaddset(&mask, sig);
4068 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4069 for_each_thread(p, t)
4070 flush_sigqueue_mask(&mask, &t->pending);
4071 }
4072 }
4073
4074 spin_unlock_irq(&p->sighand->siglock);
4075 return 0;
4076}
4077
4078static int
4079do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4080 size_t min_ss_size)
4081{
4082 struct task_struct *t = current;
4083
4084 if (oss) {
4085 memset(oss, 0, sizeof(stack_t));
4086 oss->ss_sp = (void __user *) t->sas_ss_sp;
4087 oss->ss_size = t->sas_ss_size;
4088 oss->ss_flags = sas_ss_flags(sp) |
4089 (current->sas_ss_flags & SS_FLAG_BITS);
4090 }
4091
4092 if (ss) {
4093 void __user *ss_sp = ss->ss_sp;
4094 size_t ss_size = ss->ss_size;
4095 unsigned ss_flags = ss->ss_flags;
4096 int ss_mode;
4097
4098 if (unlikely(on_sig_stack(sp)))
4099 return -EPERM;
4100
4101 ss_mode = ss_flags & ~SS_FLAG_BITS;
4102 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4103 ss_mode != 0))
4104 return -EINVAL;
4105
4106 if (ss_mode == SS_DISABLE) {
4107 ss_size = 0;
4108 ss_sp = NULL;
4109 } else {
4110 if (unlikely(ss_size < min_ss_size))
4111 return -ENOMEM;
4112 }
4113
4114 t->sas_ss_sp = (unsigned long) ss_sp;
4115 t->sas_ss_size = ss_size;
4116 t->sas_ss_flags = ss_flags;
4117 }
4118 return 0;
4119}
4120
4121SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4122{
4123 stack_t new, old;
4124 int err;
4125 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4126 return -EFAULT;
4127 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4128 current_user_stack_pointer(),
4129 MINSIGSTKSZ);
4130 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4131 err = -EFAULT;
4132 return err;
4133}
4134
4135int restore_altstack(const stack_t __user *uss)
4136{
4137 stack_t new;
4138 if (copy_from_user(&new, uss, sizeof(stack_t)))
4139 return -EFAULT;
4140 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4141 MINSIGSTKSZ);
4142 /* squash all but EFAULT for now */
4143 return 0;
4144}
4145
4146int __save_altstack(stack_t __user *uss, unsigned long sp)
4147{
4148 struct task_struct *t = current;
4149 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4150 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4151 __put_user(t->sas_ss_size, &uss->ss_size);
4152 return err;
4153}
4154
4155#ifdef CONFIG_COMPAT
4156static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4157 compat_stack_t __user *uoss_ptr)
4158{
4159 stack_t uss, uoss;
4160 int ret;
4161
4162 if (uss_ptr) {
4163 compat_stack_t uss32;
4164 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4165 return -EFAULT;
4166 uss.ss_sp = compat_ptr(uss32.ss_sp);
4167 uss.ss_flags = uss32.ss_flags;
4168 uss.ss_size = uss32.ss_size;
4169 }
4170 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4171 compat_user_stack_pointer(),
4172 COMPAT_MINSIGSTKSZ);
4173 if (ret >= 0 && uoss_ptr) {
4174 compat_stack_t old;
4175 memset(&old, 0, sizeof(old));
4176 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4177 old.ss_flags = uoss.ss_flags;
4178 old.ss_size = uoss.ss_size;
4179 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4180 ret = -EFAULT;
4181 }
4182 return ret;
4183}
4184
4185COMPAT_SYSCALL_DEFINE2(sigaltstack,
4186 const compat_stack_t __user *, uss_ptr,
4187 compat_stack_t __user *, uoss_ptr)
4188{
4189 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4190}
4191
4192int compat_restore_altstack(const compat_stack_t __user *uss)
4193{
4194 int err = do_compat_sigaltstack(uss, NULL);
4195 /* squash all but -EFAULT for now */
4196 return err == -EFAULT ? err : 0;
4197}
4198
4199int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4200{
4201 int err;
4202 struct task_struct *t = current;
4203 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4204 &uss->ss_sp) |
4205 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4206 __put_user(t->sas_ss_size, &uss->ss_size);
4207 return err;
4208}
4209#endif
4210
4211#ifdef __ARCH_WANT_SYS_SIGPENDING
4212
4213/**
4214 * sys_sigpending - examine pending signals
4215 * @uset: where mask of pending signal is returned
4216 */
4217SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4218{
4219 sigset_t set;
4220
4221 if (sizeof(old_sigset_t) > sizeof(*uset))
4222 return -EINVAL;
4223
4224 do_sigpending(&set);
4225
4226 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4227 return -EFAULT;
4228
4229 return 0;
4230}
4231
4232#ifdef CONFIG_COMPAT
4233COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4234{
4235 sigset_t set;
4236
4237 do_sigpending(&set);
4238
4239 return put_user(set.sig[0], set32);
4240}
4241#endif
4242
4243#endif
4244
4245#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4246/**
4247 * sys_sigprocmask - examine and change blocked signals
4248 * @how: whether to add, remove, or set signals
4249 * @nset: signals to add or remove (if non-null)
4250 * @oset: previous value of signal mask if non-null
4251 *
4252 * Some platforms have their own version with special arguments;
4253 * others support only sys_rt_sigprocmask.
4254 */
4255
4256SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4257 old_sigset_t __user *, oset)
4258{
4259 old_sigset_t old_set, new_set;
4260 sigset_t new_blocked;
4261
4262 old_set = current->blocked.sig[0];
4263
4264 if (nset) {
4265 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4266 return -EFAULT;
4267
4268 new_blocked = current->blocked;
4269
4270 switch (how) {
4271 case SIG_BLOCK:
4272 sigaddsetmask(&new_blocked, new_set);
4273 break;
4274 case SIG_UNBLOCK:
4275 sigdelsetmask(&new_blocked, new_set);
4276 break;
4277 case SIG_SETMASK:
4278 new_blocked.sig[0] = new_set;
4279 break;
4280 default:
4281 return -EINVAL;
4282 }
4283
4284 set_current_blocked(&new_blocked);
4285 }
4286
4287 if (oset) {
4288 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4289 return -EFAULT;
4290 }
4291
4292 return 0;
4293}
4294#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4295
4296#ifndef CONFIG_ODD_RT_SIGACTION
4297/**
4298 * sys_rt_sigaction - alter an action taken by a process
4299 * @sig: signal to be sent
4300 * @act: new sigaction
4301 * @oact: used to save the previous sigaction
4302 * @sigsetsize: size of sigset_t type
4303 */
4304SYSCALL_DEFINE4(rt_sigaction, int, sig,
4305 const struct sigaction __user *, act,
4306 struct sigaction __user *, oact,
4307 size_t, sigsetsize)
4308{
4309 struct k_sigaction new_sa, old_sa;
4310 int ret;
4311
4312 /* XXX: Don't preclude handling different sized sigset_t's. */
4313 if (sigsetsize != sizeof(sigset_t))
4314 return -EINVAL;
4315
4316 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4317 return -EFAULT;
4318
4319 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4320 if (ret)
4321 return ret;
4322
4323 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4324 return -EFAULT;
4325
4326 return 0;
4327}
4328#ifdef CONFIG_COMPAT
4329COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4330 const struct compat_sigaction __user *, act,
4331 struct compat_sigaction __user *, oact,
4332 compat_size_t, sigsetsize)
4333{
4334 struct k_sigaction new_ka, old_ka;
4335#ifdef __ARCH_HAS_SA_RESTORER
4336 compat_uptr_t restorer;
4337#endif
4338 int ret;
4339
4340 /* XXX: Don't preclude handling different sized sigset_t's. */
4341 if (sigsetsize != sizeof(compat_sigset_t))
4342 return -EINVAL;
4343
4344 if (act) {
4345 compat_uptr_t handler;
4346 ret = get_user(handler, &act->sa_handler);
4347 new_ka.sa.sa_handler = compat_ptr(handler);
4348#ifdef __ARCH_HAS_SA_RESTORER
4349 ret |= get_user(restorer, &act->sa_restorer);
4350 new_ka.sa.sa_restorer = compat_ptr(restorer);
4351#endif
4352 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4353 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4354 if (ret)
4355 return -EFAULT;
4356 }
4357
4358 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4359 if (!ret && oact) {
4360 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4361 &oact->sa_handler);
4362 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4363 sizeof(oact->sa_mask));
4364 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4365#ifdef __ARCH_HAS_SA_RESTORER
4366 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4367 &oact->sa_restorer);
4368#endif
4369 }
4370 return ret;
4371}
4372#endif
4373#endif /* !CONFIG_ODD_RT_SIGACTION */
4374
4375#ifdef CONFIG_OLD_SIGACTION
4376SYSCALL_DEFINE3(sigaction, int, sig,
4377 const struct old_sigaction __user *, act,
4378 struct old_sigaction __user *, oact)
4379{
4380 struct k_sigaction new_ka, old_ka;
4381 int ret;
4382
4383 if (act) {
4384 old_sigset_t mask;
4385 if (!access_ok(act, sizeof(*act)) ||
4386 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4387 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4388 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4389 __get_user(mask, &act->sa_mask))
4390 return -EFAULT;
4391#ifdef __ARCH_HAS_KA_RESTORER
4392 new_ka.ka_restorer = NULL;
4393#endif
4394 siginitset(&new_ka.sa.sa_mask, mask);
4395 }
4396
4397 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4398
4399 if (!ret && oact) {
4400 if (!access_ok(oact, sizeof(*oact)) ||
4401 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4402 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4403 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4404 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4405 return -EFAULT;
4406 }
4407
4408 return ret;
4409}
4410#endif
4411#ifdef CONFIG_COMPAT_OLD_SIGACTION
4412COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4413 const struct compat_old_sigaction __user *, act,
4414 struct compat_old_sigaction __user *, oact)
4415{
4416 struct k_sigaction new_ka, old_ka;
4417 int ret;
4418 compat_old_sigset_t mask;
4419 compat_uptr_t handler, restorer;
4420
4421 if (act) {
4422 if (!access_ok(act, sizeof(*act)) ||
4423 __get_user(handler, &act->sa_handler) ||
4424 __get_user(restorer, &act->sa_restorer) ||
4425 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4426 __get_user(mask, &act->sa_mask))
4427 return -EFAULT;
4428
4429#ifdef __ARCH_HAS_KA_RESTORER
4430 new_ka.ka_restorer = NULL;
4431#endif
4432 new_ka.sa.sa_handler = compat_ptr(handler);
4433 new_ka.sa.sa_restorer = compat_ptr(restorer);
4434 siginitset(&new_ka.sa.sa_mask, mask);
4435 }
4436
4437 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4438
4439 if (!ret && oact) {
4440 if (!access_ok(oact, sizeof(*oact)) ||
4441 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4442 &oact->sa_handler) ||
4443 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4444 &oact->sa_restorer) ||
4445 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4446 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4447 return -EFAULT;
4448 }
4449 return ret;
4450}
4451#endif
4452
4453#ifdef CONFIG_SGETMASK_SYSCALL
4454
4455/*
4456 * For backwards compatibility. Functionality superseded by sigprocmask.
4457 */
4458SYSCALL_DEFINE0(sgetmask)
4459{
4460 /* SMP safe */
4461 return current->blocked.sig[0];
4462}
4463
4464SYSCALL_DEFINE1(ssetmask, int, newmask)
4465{
4466 int old = current->blocked.sig[0];
4467 sigset_t newset;
4468
4469 siginitset(&newset, newmask);
4470 set_current_blocked(&newset);
4471
4472 return old;
4473}
4474#endif /* CONFIG_SGETMASK_SYSCALL */
4475
4476#ifdef __ARCH_WANT_SYS_SIGNAL
4477/*
4478 * For backwards compatibility. Functionality superseded by sigaction.
4479 */
4480SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4481{
4482 struct k_sigaction new_sa, old_sa;
4483 int ret;
4484
4485 new_sa.sa.sa_handler = handler;
4486 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4487 sigemptyset(&new_sa.sa.sa_mask);
4488
4489 ret = do_sigaction(sig, &new_sa, &old_sa);
4490
4491 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4492}
4493#endif /* __ARCH_WANT_SYS_SIGNAL */
4494
4495#ifdef __ARCH_WANT_SYS_PAUSE
4496
4497SYSCALL_DEFINE0(pause)
4498{
4499 while (!signal_pending(current)) {
4500 __set_current_state(TASK_INTERRUPTIBLE);
4501 schedule();
4502 }
4503 return -ERESTARTNOHAND;
4504}
4505
4506#endif
4507
4508static int sigsuspend(sigset_t *set)
4509{
4510 current->saved_sigmask = current->blocked;
4511 set_current_blocked(set);
4512
4513 while (!signal_pending(current)) {
4514 __set_current_state(TASK_INTERRUPTIBLE);
4515 schedule();
4516 }
4517 set_restore_sigmask();
4518 return -ERESTARTNOHAND;
4519}
4520
4521/**
4522 * sys_rt_sigsuspend - replace the signal mask for a value with the
4523 * @unewset value until a signal is received
4524 * @unewset: new signal mask value
4525 * @sigsetsize: size of sigset_t type
4526 */
4527SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4528{
4529 sigset_t newset;
4530
4531 /* XXX: Don't preclude handling different sized sigset_t's. */
4532 if (sigsetsize != sizeof(sigset_t))
4533 return -EINVAL;
4534
4535 if (copy_from_user(&newset, unewset, sizeof(newset)))
4536 return -EFAULT;
4537 return sigsuspend(&newset);
4538}
4539
4540#ifdef CONFIG_COMPAT
4541COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4542{
4543 sigset_t newset;
4544
4545 /* XXX: Don't preclude handling different sized sigset_t's. */
4546 if (sigsetsize != sizeof(sigset_t))
4547 return -EINVAL;
4548
4549 if (get_compat_sigset(&newset, unewset))
4550 return -EFAULT;
4551 return sigsuspend(&newset);
4552}
4553#endif
4554
4555#ifdef CONFIG_OLD_SIGSUSPEND
4556SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4557{
4558 sigset_t blocked;
4559 siginitset(&blocked, mask);
4560 return sigsuspend(&blocked);
4561}
4562#endif
4563#ifdef CONFIG_OLD_SIGSUSPEND3
4564SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4565{
4566 sigset_t blocked;
4567 siginitset(&blocked, mask);
4568 return sigsuspend(&blocked);
4569}
4570#endif
4571
4572__weak const char *arch_vma_name(struct vm_area_struct *vma)
4573{
4574 return NULL;
4575}
4576
4577static inline void siginfo_buildtime_checks(void)
4578{
4579 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4580
4581 /* Verify the offsets in the two siginfos match */
4582#define CHECK_OFFSET(field) \
4583 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4584
4585 /* kill */
4586 CHECK_OFFSET(si_pid);
4587 CHECK_OFFSET(si_uid);
4588
4589 /* timer */
4590 CHECK_OFFSET(si_tid);
4591 CHECK_OFFSET(si_overrun);
4592 CHECK_OFFSET(si_value);
4593
4594 /* rt */
4595 CHECK_OFFSET(si_pid);
4596 CHECK_OFFSET(si_uid);
4597 CHECK_OFFSET(si_value);
4598
4599 /* sigchld */
4600 CHECK_OFFSET(si_pid);
4601 CHECK_OFFSET(si_uid);
4602 CHECK_OFFSET(si_status);
4603 CHECK_OFFSET(si_utime);
4604 CHECK_OFFSET(si_stime);
4605
4606 /* sigfault */
4607 CHECK_OFFSET(si_addr);
4608 CHECK_OFFSET(si_trapno);
4609 CHECK_OFFSET(si_addr_lsb);
4610 CHECK_OFFSET(si_lower);
4611 CHECK_OFFSET(si_upper);
4612 CHECK_OFFSET(si_pkey);
4613 CHECK_OFFSET(si_perf_data);
4614 CHECK_OFFSET(si_perf_type);
4615
4616 /* sigpoll */
4617 CHECK_OFFSET(si_band);
4618 CHECK_OFFSET(si_fd);
4619
4620 /* sigsys */
4621 CHECK_OFFSET(si_call_addr);
4622 CHECK_OFFSET(si_syscall);
4623 CHECK_OFFSET(si_arch);
4624#undef CHECK_OFFSET
4625
4626 /* usb asyncio */
4627 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4628 offsetof(struct siginfo, si_addr));
4629 if (sizeof(int) == sizeof(void __user *)) {
4630 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4631 sizeof(void __user *));
4632 } else {
4633 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4634 sizeof_field(struct siginfo, si_uid)) !=
4635 sizeof(void __user *));
4636 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4637 offsetof(struct siginfo, si_uid));
4638 }
4639#ifdef CONFIG_COMPAT
4640 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4641 offsetof(struct compat_siginfo, si_addr));
4642 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4643 sizeof(compat_uptr_t));
4644 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4645 sizeof_field(struct siginfo, si_pid));
4646#endif
4647}
4648
4649void __init signals_init(void)
4650{
4651 siginfo_buildtime_checks();
4652
4653 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4654}
4655
4656#ifdef CONFIG_KGDB_KDB
4657#include <linux/kdb.h>
4658/*
4659 * kdb_send_sig - Allows kdb to send signals without exposing
4660 * signal internals. This function checks if the required locks are
4661 * available before calling the main signal code, to avoid kdb
4662 * deadlocks.
4663 */
4664void kdb_send_sig(struct task_struct *t, int sig)
4665{
4666 static struct task_struct *kdb_prev_t;
4667 int new_t, ret;
4668 if (!spin_trylock(&t->sighand->siglock)) {
4669 kdb_printf("Can't do kill command now.\n"
4670 "The sigmask lock is held somewhere else in "
4671 "kernel, try again later\n");
4672 return;
4673 }
4674 new_t = kdb_prev_t != t;
4675 kdb_prev_t = t;
4676 if (!task_is_running(t) && new_t) {
4677 spin_unlock(&t->sighand->siglock);
4678 kdb_printf("Process is not RUNNING, sending a signal from "
4679 "kdb risks deadlock\n"
4680 "on the run queue locks. "
4681 "The signal has _not_ been sent.\n"
4682 "Reissue the kill command if you want to risk "
4683 "the deadlock.\n");
4684 return;
4685 }
4686 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4687 spin_unlock(&t->sighand->siglock);
4688 if (ret)
4689 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4690 sig, t->pid);
4691 else
4692 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4693}
4694#endif /* CONFIG_KGDB_KDB */