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1/*
2 * linux/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
7 *
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
11 */
12
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/fs.h>
18#include <linux/tty.h>
19#include <linux/binfmts.h>
20#include <linux/coredump.h>
21#include <linux/security.h>
22#include <linux/syscalls.h>
23#include <linux/ptrace.h>
24#include <linux/signal.h>
25#include <linux/signalfd.h>
26#include <linux/ratelimit.h>
27#include <linux/tracehook.h>
28#include <linux/capability.h>
29#include <linux/freezer.h>
30#include <linux/pid_namespace.h>
31#include <linux/nsproxy.h>
32#include <linux/user_namespace.h>
33#include <linux/uprobes.h>
34#include <linux/compat.h>
35#include <linux/cn_proc.h>
36#include <linux/compiler.h>
37
38#define CREATE_TRACE_POINTS
39#include <trace/events/signal.h>
40
41#include <asm/param.h>
42#include <asm/uaccess.h>
43#include <asm/unistd.h>
44#include <asm/siginfo.h>
45#include <asm/cacheflush.h>
46#include "audit.h" /* audit_signal_info() */
47
48/*
49 * SLAB caches for signal bits.
50 */
51
52static struct kmem_cache *sigqueue_cachep;
53
54int print_fatal_signals __read_mostly;
55
56static void __user *sig_handler(struct task_struct *t, int sig)
57{
58 return t->sighand->action[sig - 1].sa.sa_handler;
59}
60
61static int sig_handler_ignored(void __user *handler, int sig)
62{
63 /* Is it explicitly or implicitly ignored? */
64 return handler == SIG_IGN ||
65 (handler == SIG_DFL && sig_kernel_ignore(sig));
66}
67
68static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69{
70 void __user *handler;
71
72 handler = sig_handler(t, sig);
73
74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 handler == SIG_DFL && !force)
76 return 1;
77
78 return sig_handler_ignored(handler, sig);
79}
80
81static int sig_ignored(struct task_struct *t, int sig, bool force)
82{
83 /*
84 * Blocked signals are never ignored, since the
85 * signal handler may change by the time it is
86 * unblocked.
87 */
88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 return 0;
90
91 if (!sig_task_ignored(t, sig, force))
92 return 0;
93
94 /*
95 * Tracers may want to know about even ignored signals.
96 */
97 return !t->ptrace;
98}
99
100/*
101 * Re-calculate pending state from the set of locally pending
102 * signals, globally pending signals, and blocked signals.
103 */
104static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105{
106 unsigned long ready;
107 long i;
108
109 switch (_NSIG_WORDS) {
110 default:
111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 ready |= signal->sig[i] &~ blocked->sig[i];
113 break;
114
115 case 4: ready = signal->sig[3] &~ blocked->sig[3];
116 ready |= signal->sig[2] &~ blocked->sig[2];
117 ready |= signal->sig[1] &~ blocked->sig[1];
118 ready |= signal->sig[0] &~ blocked->sig[0];
119 break;
120
121 case 2: ready = signal->sig[1] &~ blocked->sig[1];
122 ready |= signal->sig[0] &~ blocked->sig[0];
123 break;
124
125 case 1: ready = signal->sig[0] &~ blocked->sig[0];
126 }
127 return ready != 0;
128}
129
130#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131
132static int recalc_sigpending_tsk(struct task_struct *t)
133{
134 if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 PENDING(&t->pending, &t->blocked) ||
136 PENDING(&t->signal->shared_pending, &t->blocked)) {
137 set_tsk_thread_flag(t, TIF_SIGPENDING);
138 return 1;
139 }
140 /*
141 * We must never clear the flag in another thread, or in current
142 * when it's possible the current syscall is returning -ERESTART*.
143 * So we don't clear it here, and only callers who know they should do.
144 */
145 return 0;
146}
147
148/*
149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150 * This is superfluous when called on current, the wakeup is a harmless no-op.
151 */
152void recalc_sigpending_and_wake(struct task_struct *t)
153{
154 if (recalc_sigpending_tsk(t))
155 signal_wake_up(t, 0);
156}
157
158void recalc_sigpending(void)
159{
160 if (!recalc_sigpending_tsk(current) && !freezing(current))
161 clear_thread_flag(TIF_SIGPENDING);
162
163}
164
165/* Given the mask, find the first available signal that should be serviced. */
166
167#define SYNCHRONOUS_MASK \
168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170
171int next_signal(struct sigpending *pending, sigset_t *mask)
172{
173 unsigned long i, *s, *m, x;
174 int sig = 0;
175
176 s = pending->signal.sig;
177 m = mask->sig;
178
179 /*
180 * Handle the first word specially: it contains the
181 * synchronous signals that need to be dequeued first.
182 */
183 x = *s &~ *m;
184 if (x) {
185 if (x & SYNCHRONOUS_MASK)
186 x &= SYNCHRONOUS_MASK;
187 sig = ffz(~x) + 1;
188 return sig;
189 }
190
191 switch (_NSIG_WORDS) {
192 default:
193 for (i = 1; i < _NSIG_WORDS; ++i) {
194 x = *++s &~ *++m;
195 if (!x)
196 continue;
197 sig = ffz(~x) + i*_NSIG_BPW + 1;
198 break;
199 }
200 break;
201
202 case 2:
203 x = s[1] &~ m[1];
204 if (!x)
205 break;
206 sig = ffz(~x) + _NSIG_BPW + 1;
207 break;
208
209 case 1:
210 /* Nothing to do */
211 break;
212 }
213
214 return sig;
215}
216
217static inline void print_dropped_signal(int sig)
218{
219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220
221 if (!print_fatal_signals)
222 return;
223
224 if (!__ratelimit(&ratelimit_state))
225 return;
226
227 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 current->comm, current->pid, sig);
229}
230
231/**
232 * task_set_jobctl_pending - set jobctl pending bits
233 * @task: target task
234 * @mask: pending bits to set
235 *
236 * Clear @mask from @task->jobctl. @mask must be subset of
237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
239 * cleared. If @task is already being killed or exiting, this function
240 * becomes noop.
241 *
242 * CONTEXT:
243 * Must be called with @task->sighand->siglock held.
244 *
245 * RETURNS:
246 * %true if @mask is set, %false if made noop because @task was dying.
247 */
248bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
249{
250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253
254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 return false;
256
257 if (mask & JOBCTL_STOP_SIGMASK)
258 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259
260 task->jobctl |= mask;
261 return true;
262}
263
264/**
265 * task_clear_jobctl_trapping - clear jobctl trapping bit
266 * @task: target task
267 *
268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269 * Clear it and wake up the ptracer. Note that we don't need any further
270 * locking. @task->siglock guarantees that @task->parent points to the
271 * ptracer.
272 *
273 * CONTEXT:
274 * Must be called with @task->sighand->siglock held.
275 */
276void task_clear_jobctl_trapping(struct task_struct *task)
277{
278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 task->jobctl &= ~JOBCTL_TRAPPING;
280 smp_mb(); /* advised by wake_up_bit() */
281 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
282 }
283}
284
285/**
286 * task_clear_jobctl_pending - clear jobctl pending bits
287 * @task: target task
288 * @mask: pending bits to clear
289 *
290 * Clear @mask from @task->jobctl. @mask must be subset of
291 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
292 * STOP bits are cleared together.
293 *
294 * If clearing of @mask leaves no stop or trap pending, this function calls
295 * task_clear_jobctl_trapping().
296 *
297 * CONTEXT:
298 * Must be called with @task->sighand->siglock held.
299 */
300void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
301{
302 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
303
304 if (mask & JOBCTL_STOP_PENDING)
305 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
306
307 task->jobctl &= ~mask;
308
309 if (!(task->jobctl & JOBCTL_PENDING_MASK))
310 task_clear_jobctl_trapping(task);
311}
312
313/**
314 * task_participate_group_stop - participate in a group stop
315 * @task: task participating in a group stop
316 *
317 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
318 * Group stop states are cleared and the group stop count is consumed if
319 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
320 * stop, the appropriate %SIGNAL_* flags are set.
321 *
322 * CONTEXT:
323 * Must be called with @task->sighand->siglock held.
324 *
325 * RETURNS:
326 * %true if group stop completion should be notified to the parent, %false
327 * otherwise.
328 */
329static bool task_participate_group_stop(struct task_struct *task)
330{
331 struct signal_struct *sig = task->signal;
332 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
333
334 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
335
336 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
337
338 if (!consume)
339 return false;
340
341 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
342 sig->group_stop_count--;
343
344 /*
345 * Tell the caller to notify completion iff we are entering into a
346 * fresh group stop. Read comment in do_signal_stop() for details.
347 */
348 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
349 sig->flags = SIGNAL_STOP_STOPPED;
350 return true;
351 }
352 return false;
353}
354
355/*
356 * allocate a new signal queue record
357 * - this may be called without locks if and only if t == current, otherwise an
358 * appropriate lock must be held to stop the target task from exiting
359 */
360static struct sigqueue *
361__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
362{
363 struct sigqueue *q = NULL;
364 struct user_struct *user;
365
366 /*
367 * Protect access to @t credentials. This can go away when all
368 * callers hold rcu read lock.
369 */
370 rcu_read_lock();
371 user = get_uid(__task_cred(t)->user);
372 atomic_inc(&user->sigpending);
373 rcu_read_unlock();
374
375 if (override_rlimit ||
376 atomic_read(&user->sigpending) <=
377 task_rlimit(t, RLIMIT_SIGPENDING)) {
378 q = kmem_cache_alloc(sigqueue_cachep, flags);
379 } else {
380 print_dropped_signal(sig);
381 }
382
383 if (unlikely(q == NULL)) {
384 atomic_dec(&user->sigpending);
385 free_uid(user);
386 } else {
387 INIT_LIST_HEAD(&q->list);
388 q->flags = 0;
389 q->user = user;
390 }
391
392 return q;
393}
394
395static void __sigqueue_free(struct sigqueue *q)
396{
397 if (q->flags & SIGQUEUE_PREALLOC)
398 return;
399 atomic_dec(&q->user->sigpending);
400 free_uid(q->user);
401 kmem_cache_free(sigqueue_cachep, q);
402}
403
404void flush_sigqueue(struct sigpending *queue)
405{
406 struct sigqueue *q;
407
408 sigemptyset(&queue->signal);
409 while (!list_empty(&queue->list)) {
410 q = list_entry(queue->list.next, struct sigqueue , list);
411 list_del_init(&q->list);
412 __sigqueue_free(q);
413 }
414}
415
416/*
417 * Flush all pending signals for this kthread.
418 */
419void flush_signals(struct task_struct *t)
420{
421 unsigned long flags;
422
423 spin_lock_irqsave(&t->sighand->siglock, flags);
424 clear_tsk_thread_flag(t, TIF_SIGPENDING);
425 flush_sigqueue(&t->pending);
426 flush_sigqueue(&t->signal->shared_pending);
427 spin_unlock_irqrestore(&t->sighand->siglock, flags);
428}
429
430static void __flush_itimer_signals(struct sigpending *pending)
431{
432 sigset_t signal, retain;
433 struct sigqueue *q, *n;
434
435 signal = pending->signal;
436 sigemptyset(&retain);
437
438 list_for_each_entry_safe(q, n, &pending->list, list) {
439 int sig = q->info.si_signo;
440
441 if (likely(q->info.si_code != SI_TIMER)) {
442 sigaddset(&retain, sig);
443 } else {
444 sigdelset(&signal, sig);
445 list_del_init(&q->list);
446 __sigqueue_free(q);
447 }
448 }
449
450 sigorsets(&pending->signal, &signal, &retain);
451}
452
453void flush_itimer_signals(void)
454{
455 struct task_struct *tsk = current;
456 unsigned long flags;
457
458 spin_lock_irqsave(&tsk->sighand->siglock, flags);
459 __flush_itimer_signals(&tsk->pending);
460 __flush_itimer_signals(&tsk->signal->shared_pending);
461 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
462}
463
464void ignore_signals(struct task_struct *t)
465{
466 int i;
467
468 for (i = 0; i < _NSIG; ++i)
469 t->sighand->action[i].sa.sa_handler = SIG_IGN;
470
471 flush_signals(t);
472}
473
474/*
475 * Flush all handlers for a task.
476 */
477
478void
479flush_signal_handlers(struct task_struct *t, int force_default)
480{
481 int i;
482 struct k_sigaction *ka = &t->sighand->action[0];
483 for (i = _NSIG ; i != 0 ; i--) {
484 if (force_default || ka->sa.sa_handler != SIG_IGN)
485 ka->sa.sa_handler = SIG_DFL;
486 ka->sa.sa_flags = 0;
487#ifdef __ARCH_HAS_SA_RESTORER
488 ka->sa.sa_restorer = NULL;
489#endif
490 sigemptyset(&ka->sa.sa_mask);
491 ka++;
492 }
493}
494
495int unhandled_signal(struct task_struct *tsk, int sig)
496{
497 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
498 if (is_global_init(tsk))
499 return 1;
500 if (handler != SIG_IGN && handler != SIG_DFL)
501 return 0;
502 /* if ptraced, let the tracer determine */
503 return !tsk->ptrace;
504}
505
506static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
507{
508 struct sigqueue *q, *first = NULL;
509
510 /*
511 * Collect the siginfo appropriate to this signal. Check if
512 * there is another siginfo for the same signal.
513 */
514 list_for_each_entry(q, &list->list, list) {
515 if (q->info.si_signo == sig) {
516 if (first)
517 goto still_pending;
518 first = q;
519 }
520 }
521
522 sigdelset(&list->signal, sig);
523
524 if (first) {
525still_pending:
526 list_del_init(&first->list);
527 copy_siginfo(info, &first->info);
528 __sigqueue_free(first);
529 } else {
530 /*
531 * Ok, it wasn't in the queue. This must be
532 * a fast-pathed signal or we must have been
533 * out of queue space. So zero out the info.
534 */
535 info->si_signo = sig;
536 info->si_errno = 0;
537 info->si_code = SI_USER;
538 info->si_pid = 0;
539 info->si_uid = 0;
540 }
541}
542
543static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
544 siginfo_t *info)
545{
546 int sig = next_signal(pending, mask);
547
548 if (sig)
549 collect_signal(sig, pending, info);
550 return sig;
551}
552
553/*
554 * Dequeue a signal and return the element to the caller, which is
555 * expected to free it.
556 *
557 * All callers have to hold the siglock.
558 */
559int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
560{
561 int signr;
562
563 /* We only dequeue private signals from ourselves, we don't let
564 * signalfd steal them
565 */
566 signr = __dequeue_signal(&tsk->pending, mask, info);
567 if (!signr) {
568 signr = __dequeue_signal(&tsk->signal->shared_pending,
569 mask, info);
570 /*
571 * itimer signal ?
572 *
573 * itimers are process shared and we restart periodic
574 * itimers in the signal delivery path to prevent DoS
575 * attacks in the high resolution timer case. This is
576 * compliant with the old way of self-restarting
577 * itimers, as the SIGALRM is a legacy signal and only
578 * queued once. Changing the restart behaviour to
579 * restart the timer in the signal dequeue path is
580 * reducing the timer noise on heavy loaded !highres
581 * systems too.
582 */
583 if (unlikely(signr == SIGALRM)) {
584 struct hrtimer *tmr = &tsk->signal->real_timer;
585
586 if (!hrtimer_is_queued(tmr) &&
587 tsk->signal->it_real_incr.tv64 != 0) {
588 hrtimer_forward(tmr, tmr->base->get_time(),
589 tsk->signal->it_real_incr);
590 hrtimer_restart(tmr);
591 }
592 }
593 }
594
595 recalc_sigpending();
596 if (!signr)
597 return 0;
598
599 if (unlikely(sig_kernel_stop(signr))) {
600 /*
601 * Set a marker that we have dequeued a stop signal. Our
602 * caller might release the siglock and then the pending
603 * stop signal it is about to process is no longer in the
604 * pending bitmasks, but must still be cleared by a SIGCONT
605 * (and overruled by a SIGKILL). So those cases clear this
606 * shared flag after we've set it. Note that this flag may
607 * remain set after the signal we return is ignored or
608 * handled. That doesn't matter because its only purpose
609 * is to alert stop-signal processing code when another
610 * processor has come along and cleared the flag.
611 */
612 current->jobctl |= JOBCTL_STOP_DEQUEUED;
613 }
614 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
615 /*
616 * Release the siglock to ensure proper locking order
617 * of timer locks outside of siglocks. Note, we leave
618 * irqs disabled here, since the posix-timers code is
619 * about to disable them again anyway.
620 */
621 spin_unlock(&tsk->sighand->siglock);
622 do_schedule_next_timer(info);
623 spin_lock(&tsk->sighand->siglock);
624 }
625 return signr;
626}
627
628/*
629 * Tell a process that it has a new active signal..
630 *
631 * NOTE! we rely on the previous spin_lock to
632 * lock interrupts for us! We can only be called with
633 * "siglock" held, and the local interrupt must
634 * have been disabled when that got acquired!
635 *
636 * No need to set need_resched since signal event passing
637 * goes through ->blocked
638 */
639void signal_wake_up_state(struct task_struct *t, unsigned int state)
640{
641 set_tsk_thread_flag(t, TIF_SIGPENDING);
642 /*
643 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
644 * case. We don't check t->state here because there is a race with it
645 * executing another processor and just now entering stopped state.
646 * By using wake_up_state, we ensure the process will wake up and
647 * handle its death signal.
648 */
649 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
650 kick_process(t);
651}
652
653/*
654 * Remove signals in mask from the pending set and queue.
655 * Returns 1 if any signals were found.
656 *
657 * All callers must be holding the siglock.
658 */
659static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
660{
661 struct sigqueue *q, *n;
662 sigset_t m;
663
664 sigandsets(&m, mask, &s->signal);
665 if (sigisemptyset(&m))
666 return 0;
667
668 sigandnsets(&s->signal, &s->signal, mask);
669 list_for_each_entry_safe(q, n, &s->list, list) {
670 if (sigismember(mask, q->info.si_signo)) {
671 list_del_init(&q->list);
672 __sigqueue_free(q);
673 }
674 }
675 return 1;
676}
677
678static inline int is_si_special(const struct siginfo *info)
679{
680 return info <= SEND_SIG_FORCED;
681}
682
683static inline bool si_fromuser(const struct siginfo *info)
684{
685 return info == SEND_SIG_NOINFO ||
686 (!is_si_special(info) && SI_FROMUSER(info));
687}
688
689/*
690 * called with RCU read lock from check_kill_permission()
691 */
692static int kill_ok_by_cred(struct task_struct *t)
693{
694 const struct cred *cred = current_cred();
695 const struct cred *tcred = __task_cred(t);
696
697 if (uid_eq(cred->euid, tcred->suid) ||
698 uid_eq(cred->euid, tcred->uid) ||
699 uid_eq(cred->uid, tcred->suid) ||
700 uid_eq(cred->uid, tcred->uid))
701 return 1;
702
703 if (ns_capable(tcred->user_ns, CAP_KILL))
704 return 1;
705
706 return 0;
707}
708
709/*
710 * Bad permissions for sending the signal
711 * - the caller must hold the RCU read lock
712 */
713static int check_kill_permission(int sig, struct siginfo *info,
714 struct task_struct *t)
715{
716 struct pid *sid;
717 int error;
718
719 if (!valid_signal(sig))
720 return -EINVAL;
721
722 if (!si_fromuser(info))
723 return 0;
724
725 error = audit_signal_info(sig, t); /* Let audit system see the signal */
726 if (error)
727 return error;
728
729 if (!same_thread_group(current, t) &&
730 !kill_ok_by_cred(t)) {
731 switch (sig) {
732 case SIGCONT:
733 sid = task_session(t);
734 /*
735 * We don't return the error if sid == NULL. The
736 * task was unhashed, the caller must notice this.
737 */
738 if (!sid || sid == task_session(current))
739 break;
740 default:
741 return -EPERM;
742 }
743 }
744
745 return security_task_kill(t, info, sig, 0);
746}
747
748/**
749 * ptrace_trap_notify - schedule trap to notify ptracer
750 * @t: tracee wanting to notify tracer
751 *
752 * This function schedules sticky ptrace trap which is cleared on the next
753 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
754 * ptracer.
755 *
756 * If @t is running, STOP trap will be taken. If trapped for STOP and
757 * ptracer is listening for events, tracee is woken up so that it can
758 * re-trap for the new event. If trapped otherwise, STOP trap will be
759 * eventually taken without returning to userland after the existing traps
760 * are finished by PTRACE_CONT.
761 *
762 * CONTEXT:
763 * Must be called with @task->sighand->siglock held.
764 */
765static void ptrace_trap_notify(struct task_struct *t)
766{
767 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
768 assert_spin_locked(&t->sighand->siglock);
769
770 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
771 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
772}
773
774/*
775 * Handle magic process-wide effects of stop/continue signals. Unlike
776 * the signal actions, these happen immediately at signal-generation
777 * time regardless of blocking, ignoring, or handling. This does the
778 * actual continuing for SIGCONT, but not the actual stopping for stop
779 * signals. The process stop is done as a signal action for SIG_DFL.
780 *
781 * Returns true if the signal should be actually delivered, otherwise
782 * it should be dropped.
783 */
784static bool prepare_signal(int sig, struct task_struct *p, bool force)
785{
786 struct signal_struct *signal = p->signal;
787 struct task_struct *t;
788 sigset_t flush;
789
790 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
791 if (!(signal->flags & SIGNAL_GROUP_EXIT))
792 return sig == SIGKILL;
793 /*
794 * The process is in the middle of dying, nothing to do.
795 */
796 } else if (sig_kernel_stop(sig)) {
797 /*
798 * This is a stop signal. Remove SIGCONT from all queues.
799 */
800 siginitset(&flush, sigmask(SIGCONT));
801 flush_sigqueue_mask(&flush, &signal->shared_pending);
802 for_each_thread(p, t)
803 flush_sigqueue_mask(&flush, &t->pending);
804 } else if (sig == SIGCONT) {
805 unsigned int why;
806 /*
807 * Remove all stop signals from all queues, wake all threads.
808 */
809 siginitset(&flush, SIG_KERNEL_STOP_MASK);
810 flush_sigqueue_mask(&flush, &signal->shared_pending);
811 for_each_thread(p, t) {
812 flush_sigqueue_mask(&flush, &t->pending);
813 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
814 if (likely(!(t->ptrace & PT_SEIZED)))
815 wake_up_state(t, __TASK_STOPPED);
816 else
817 ptrace_trap_notify(t);
818 }
819
820 /*
821 * Notify the parent with CLD_CONTINUED if we were stopped.
822 *
823 * If we were in the middle of a group stop, we pretend it
824 * was already finished, and then continued. Since SIGCHLD
825 * doesn't queue we report only CLD_STOPPED, as if the next
826 * CLD_CONTINUED was dropped.
827 */
828 why = 0;
829 if (signal->flags & SIGNAL_STOP_STOPPED)
830 why |= SIGNAL_CLD_CONTINUED;
831 else if (signal->group_stop_count)
832 why |= SIGNAL_CLD_STOPPED;
833
834 if (why) {
835 /*
836 * The first thread which returns from do_signal_stop()
837 * will take ->siglock, notice SIGNAL_CLD_MASK, and
838 * notify its parent. See get_signal_to_deliver().
839 */
840 signal->flags = why | SIGNAL_STOP_CONTINUED;
841 signal->group_stop_count = 0;
842 signal->group_exit_code = 0;
843 }
844 }
845
846 return !sig_ignored(p, sig, force);
847}
848
849/*
850 * Test if P wants to take SIG. After we've checked all threads with this,
851 * it's equivalent to finding no threads not blocking SIG. Any threads not
852 * blocking SIG were ruled out because they are not running and already
853 * have pending signals. Such threads will dequeue from the shared queue
854 * as soon as they're available, so putting the signal on the shared queue
855 * will be equivalent to sending it to one such thread.
856 */
857static inline int wants_signal(int sig, struct task_struct *p)
858{
859 if (sigismember(&p->blocked, sig))
860 return 0;
861 if (p->flags & PF_EXITING)
862 return 0;
863 if (sig == SIGKILL)
864 return 1;
865 if (task_is_stopped_or_traced(p))
866 return 0;
867 return task_curr(p) || !signal_pending(p);
868}
869
870static void complete_signal(int sig, struct task_struct *p, int group)
871{
872 struct signal_struct *signal = p->signal;
873 struct task_struct *t;
874
875 /*
876 * Now find a thread we can wake up to take the signal off the queue.
877 *
878 * If the main thread wants the signal, it gets first crack.
879 * Probably the least surprising to the average bear.
880 */
881 if (wants_signal(sig, p))
882 t = p;
883 else if (!group || thread_group_empty(p))
884 /*
885 * There is just one thread and it does not need to be woken.
886 * It will dequeue unblocked signals before it runs again.
887 */
888 return;
889 else {
890 /*
891 * Otherwise try to find a suitable thread.
892 */
893 t = signal->curr_target;
894 while (!wants_signal(sig, t)) {
895 t = next_thread(t);
896 if (t == signal->curr_target)
897 /*
898 * No thread needs to be woken.
899 * Any eligible threads will see
900 * the signal in the queue soon.
901 */
902 return;
903 }
904 signal->curr_target = t;
905 }
906
907 /*
908 * Found a killable thread. If the signal will be fatal,
909 * then start taking the whole group down immediately.
910 */
911 if (sig_fatal(p, sig) &&
912 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
913 !sigismember(&t->real_blocked, sig) &&
914 (sig == SIGKILL || !t->ptrace)) {
915 /*
916 * This signal will be fatal to the whole group.
917 */
918 if (!sig_kernel_coredump(sig)) {
919 /*
920 * Start a group exit and wake everybody up.
921 * This way we don't have other threads
922 * running and doing things after a slower
923 * thread has the fatal signal pending.
924 */
925 signal->flags = SIGNAL_GROUP_EXIT;
926 signal->group_exit_code = sig;
927 signal->group_stop_count = 0;
928 t = p;
929 do {
930 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
931 sigaddset(&t->pending.signal, SIGKILL);
932 signal_wake_up(t, 1);
933 } while_each_thread(p, t);
934 return;
935 }
936 }
937
938 /*
939 * The signal is already in the shared-pending queue.
940 * Tell the chosen thread to wake up and dequeue it.
941 */
942 signal_wake_up(t, sig == SIGKILL);
943 return;
944}
945
946static inline int legacy_queue(struct sigpending *signals, int sig)
947{
948 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
949}
950
951#ifdef CONFIG_USER_NS
952static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
953{
954 if (current_user_ns() == task_cred_xxx(t, user_ns))
955 return;
956
957 if (SI_FROMKERNEL(info))
958 return;
959
960 rcu_read_lock();
961 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
962 make_kuid(current_user_ns(), info->si_uid));
963 rcu_read_unlock();
964}
965#else
966static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
967{
968 return;
969}
970#endif
971
972static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
973 int group, int from_ancestor_ns)
974{
975 struct sigpending *pending;
976 struct sigqueue *q;
977 int override_rlimit;
978 int ret = 0, result;
979
980 assert_spin_locked(&t->sighand->siglock);
981
982 result = TRACE_SIGNAL_IGNORED;
983 if (!prepare_signal(sig, t,
984 from_ancestor_ns || (info == SEND_SIG_FORCED)))
985 goto ret;
986
987 pending = group ? &t->signal->shared_pending : &t->pending;
988 /*
989 * Short-circuit ignored signals and support queuing
990 * exactly one non-rt signal, so that we can get more
991 * detailed information about the cause of the signal.
992 */
993 result = TRACE_SIGNAL_ALREADY_PENDING;
994 if (legacy_queue(pending, sig))
995 goto ret;
996
997 result = TRACE_SIGNAL_DELIVERED;
998 /*
999 * fast-pathed signals for kernel-internal things like SIGSTOP
1000 * or SIGKILL.
1001 */
1002 if (info == SEND_SIG_FORCED)
1003 goto out_set;
1004
1005 /*
1006 * Real-time signals must be queued if sent by sigqueue, or
1007 * some other real-time mechanism. It is implementation
1008 * defined whether kill() does so. We attempt to do so, on
1009 * the principle of least surprise, but since kill is not
1010 * allowed to fail with EAGAIN when low on memory we just
1011 * make sure at least one signal gets delivered and don't
1012 * pass on the info struct.
1013 */
1014 if (sig < SIGRTMIN)
1015 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1016 else
1017 override_rlimit = 0;
1018
1019 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1020 override_rlimit);
1021 if (q) {
1022 list_add_tail(&q->list, &pending->list);
1023 switch ((unsigned long) info) {
1024 case (unsigned long) SEND_SIG_NOINFO:
1025 q->info.si_signo = sig;
1026 q->info.si_errno = 0;
1027 q->info.si_code = SI_USER;
1028 q->info.si_pid = task_tgid_nr_ns(current,
1029 task_active_pid_ns(t));
1030 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1031 break;
1032 case (unsigned long) SEND_SIG_PRIV:
1033 q->info.si_signo = sig;
1034 q->info.si_errno = 0;
1035 q->info.si_code = SI_KERNEL;
1036 q->info.si_pid = 0;
1037 q->info.si_uid = 0;
1038 break;
1039 default:
1040 copy_siginfo(&q->info, info);
1041 if (from_ancestor_ns)
1042 q->info.si_pid = 0;
1043 break;
1044 }
1045
1046 userns_fixup_signal_uid(&q->info, t);
1047
1048 } else if (!is_si_special(info)) {
1049 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1050 /*
1051 * Queue overflow, abort. We may abort if the
1052 * signal was rt and sent by user using something
1053 * other than kill().
1054 */
1055 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1056 ret = -EAGAIN;
1057 goto ret;
1058 } else {
1059 /*
1060 * This is a silent loss of information. We still
1061 * send the signal, but the *info bits are lost.
1062 */
1063 result = TRACE_SIGNAL_LOSE_INFO;
1064 }
1065 }
1066
1067out_set:
1068 signalfd_notify(t, sig);
1069 sigaddset(&pending->signal, sig);
1070 complete_signal(sig, t, group);
1071ret:
1072 trace_signal_generate(sig, info, t, group, result);
1073 return ret;
1074}
1075
1076static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1077 int group)
1078{
1079 int from_ancestor_ns = 0;
1080
1081#ifdef CONFIG_PID_NS
1082 from_ancestor_ns = si_fromuser(info) &&
1083 !task_pid_nr_ns(current, task_active_pid_ns(t));
1084#endif
1085
1086 return __send_signal(sig, info, t, group, from_ancestor_ns);
1087}
1088
1089static void print_fatal_signal(int signr)
1090{
1091 struct pt_regs *regs = signal_pt_regs();
1092 printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1093
1094#if defined(__i386__) && !defined(__arch_um__)
1095 printk(KERN_INFO "code at %08lx: ", regs->ip);
1096 {
1097 int i;
1098 for (i = 0; i < 16; i++) {
1099 unsigned char insn;
1100
1101 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1102 break;
1103 printk(KERN_CONT "%02x ", insn);
1104 }
1105 }
1106 printk(KERN_CONT "\n");
1107#endif
1108 preempt_disable();
1109 show_regs(regs);
1110 preempt_enable();
1111}
1112
1113static int __init setup_print_fatal_signals(char *str)
1114{
1115 get_option (&str, &print_fatal_signals);
1116
1117 return 1;
1118}
1119
1120__setup("print-fatal-signals=", setup_print_fatal_signals);
1121
1122int
1123__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1124{
1125 return send_signal(sig, info, p, 1);
1126}
1127
1128static int
1129specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1130{
1131 return send_signal(sig, info, t, 0);
1132}
1133
1134int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1135 bool group)
1136{
1137 unsigned long flags;
1138 int ret = -ESRCH;
1139
1140 if (lock_task_sighand(p, &flags)) {
1141 ret = send_signal(sig, info, p, group);
1142 unlock_task_sighand(p, &flags);
1143 }
1144
1145 return ret;
1146}
1147
1148/*
1149 * Force a signal that the process can't ignore: if necessary
1150 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1151 *
1152 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1153 * since we do not want to have a signal handler that was blocked
1154 * be invoked when user space had explicitly blocked it.
1155 *
1156 * We don't want to have recursive SIGSEGV's etc, for example,
1157 * that is why we also clear SIGNAL_UNKILLABLE.
1158 */
1159int
1160force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1161{
1162 unsigned long int flags;
1163 int ret, blocked, ignored;
1164 struct k_sigaction *action;
1165
1166 spin_lock_irqsave(&t->sighand->siglock, flags);
1167 action = &t->sighand->action[sig-1];
1168 ignored = action->sa.sa_handler == SIG_IGN;
1169 blocked = sigismember(&t->blocked, sig);
1170 if (blocked || ignored) {
1171 action->sa.sa_handler = SIG_DFL;
1172 if (blocked) {
1173 sigdelset(&t->blocked, sig);
1174 recalc_sigpending_and_wake(t);
1175 }
1176 }
1177 if (action->sa.sa_handler == SIG_DFL)
1178 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1179 ret = specific_send_sig_info(sig, info, t);
1180 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1181
1182 return ret;
1183}
1184
1185/*
1186 * Nuke all other threads in the group.
1187 */
1188int zap_other_threads(struct task_struct *p)
1189{
1190 struct task_struct *t = p;
1191 int count = 0;
1192
1193 p->signal->group_stop_count = 0;
1194
1195 while_each_thread(p, t) {
1196 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1197 count++;
1198
1199 /* Don't bother with already dead threads */
1200 if (t->exit_state)
1201 continue;
1202 sigaddset(&t->pending.signal, SIGKILL);
1203 signal_wake_up(t, 1);
1204 }
1205
1206 return count;
1207}
1208
1209struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1210 unsigned long *flags)
1211{
1212 struct sighand_struct *sighand;
1213
1214 for (;;) {
1215 /*
1216 * Disable interrupts early to avoid deadlocks.
1217 * See rcu_read_unlock() comment header for details.
1218 */
1219 local_irq_save(*flags);
1220 rcu_read_lock();
1221 sighand = rcu_dereference(tsk->sighand);
1222 if (unlikely(sighand == NULL)) {
1223 rcu_read_unlock();
1224 local_irq_restore(*flags);
1225 break;
1226 }
1227 /*
1228 * This sighand can be already freed and even reused, but
1229 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1230 * initializes ->siglock: this slab can't go away, it has
1231 * the same object type, ->siglock can't be reinitialized.
1232 *
1233 * We need to ensure that tsk->sighand is still the same
1234 * after we take the lock, we can race with de_thread() or
1235 * __exit_signal(). In the latter case the next iteration
1236 * must see ->sighand == NULL.
1237 */
1238 spin_lock(&sighand->siglock);
1239 if (likely(sighand == tsk->sighand)) {
1240 rcu_read_unlock();
1241 break;
1242 }
1243 spin_unlock(&sighand->siglock);
1244 rcu_read_unlock();
1245 local_irq_restore(*flags);
1246 }
1247
1248 return sighand;
1249}
1250
1251/*
1252 * send signal info to all the members of a group
1253 */
1254int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1255{
1256 int ret;
1257
1258 rcu_read_lock();
1259 ret = check_kill_permission(sig, info, p);
1260 rcu_read_unlock();
1261
1262 if (!ret && sig)
1263 ret = do_send_sig_info(sig, info, p, true);
1264
1265 return ret;
1266}
1267
1268/*
1269 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1270 * control characters do (^C, ^Z etc)
1271 * - the caller must hold at least a readlock on tasklist_lock
1272 */
1273int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1274{
1275 struct task_struct *p = NULL;
1276 int retval, success;
1277
1278 success = 0;
1279 retval = -ESRCH;
1280 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1281 int err = group_send_sig_info(sig, info, p);
1282 success |= !err;
1283 retval = err;
1284 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1285 return success ? 0 : retval;
1286}
1287
1288int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1289{
1290 int error = -ESRCH;
1291 struct task_struct *p;
1292
1293 for (;;) {
1294 rcu_read_lock();
1295 p = pid_task(pid, PIDTYPE_PID);
1296 if (p)
1297 error = group_send_sig_info(sig, info, p);
1298 rcu_read_unlock();
1299 if (likely(!p || error != -ESRCH))
1300 return error;
1301
1302 /*
1303 * The task was unhashed in between, try again. If it
1304 * is dead, pid_task() will return NULL, if we race with
1305 * de_thread() it will find the new leader.
1306 */
1307 }
1308}
1309
1310int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1311{
1312 int error;
1313 rcu_read_lock();
1314 error = kill_pid_info(sig, info, find_vpid(pid));
1315 rcu_read_unlock();
1316 return error;
1317}
1318
1319static int kill_as_cred_perm(const struct cred *cred,
1320 struct task_struct *target)
1321{
1322 const struct cred *pcred = __task_cred(target);
1323 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1324 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1325 return 0;
1326 return 1;
1327}
1328
1329/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1330int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1331 const struct cred *cred, u32 secid)
1332{
1333 int ret = -EINVAL;
1334 struct task_struct *p;
1335 unsigned long flags;
1336
1337 if (!valid_signal(sig))
1338 return ret;
1339
1340 rcu_read_lock();
1341 p = pid_task(pid, PIDTYPE_PID);
1342 if (!p) {
1343 ret = -ESRCH;
1344 goto out_unlock;
1345 }
1346 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1347 ret = -EPERM;
1348 goto out_unlock;
1349 }
1350 ret = security_task_kill(p, info, sig, secid);
1351 if (ret)
1352 goto out_unlock;
1353
1354 if (sig) {
1355 if (lock_task_sighand(p, &flags)) {
1356 ret = __send_signal(sig, info, p, 1, 0);
1357 unlock_task_sighand(p, &flags);
1358 } else
1359 ret = -ESRCH;
1360 }
1361out_unlock:
1362 rcu_read_unlock();
1363 return ret;
1364}
1365EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1366
1367/*
1368 * kill_something_info() interprets pid in interesting ways just like kill(2).
1369 *
1370 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1371 * is probably wrong. Should make it like BSD or SYSV.
1372 */
1373
1374static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1375{
1376 int ret;
1377
1378 if (pid > 0) {
1379 rcu_read_lock();
1380 ret = kill_pid_info(sig, info, find_vpid(pid));
1381 rcu_read_unlock();
1382 return ret;
1383 }
1384
1385 read_lock(&tasklist_lock);
1386 if (pid != -1) {
1387 ret = __kill_pgrp_info(sig, info,
1388 pid ? find_vpid(-pid) : task_pgrp(current));
1389 } else {
1390 int retval = 0, count = 0;
1391 struct task_struct * p;
1392
1393 for_each_process(p) {
1394 if (task_pid_vnr(p) > 1 &&
1395 !same_thread_group(p, current)) {
1396 int err = group_send_sig_info(sig, info, p);
1397 ++count;
1398 if (err != -EPERM)
1399 retval = err;
1400 }
1401 }
1402 ret = count ? retval : -ESRCH;
1403 }
1404 read_unlock(&tasklist_lock);
1405
1406 return ret;
1407}
1408
1409/*
1410 * These are for backward compatibility with the rest of the kernel source.
1411 */
1412
1413int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1414{
1415 /*
1416 * Make sure legacy kernel users don't send in bad values
1417 * (normal paths check this in check_kill_permission).
1418 */
1419 if (!valid_signal(sig))
1420 return -EINVAL;
1421
1422 return do_send_sig_info(sig, info, p, false);
1423}
1424
1425#define __si_special(priv) \
1426 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1427
1428int
1429send_sig(int sig, struct task_struct *p, int priv)
1430{
1431 return send_sig_info(sig, __si_special(priv), p);
1432}
1433
1434void
1435force_sig(int sig, struct task_struct *p)
1436{
1437 force_sig_info(sig, SEND_SIG_PRIV, p);
1438}
1439
1440/*
1441 * When things go south during signal handling, we
1442 * will force a SIGSEGV. And if the signal that caused
1443 * the problem was already a SIGSEGV, we'll want to
1444 * make sure we don't even try to deliver the signal..
1445 */
1446int
1447force_sigsegv(int sig, struct task_struct *p)
1448{
1449 if (sig == SIGSEGV) {
1450 unsigned long flags;
1451 spin_lock_irqsave(&p->sighand->siglock, flags);
1452 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1453 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1454 }
1455 force_sig(SIGSEGV, p);
1456 return 0;
1457}
1458
1459int kill_pgrp(struct pid *pid, int sig, int priv)
1460{
1461 int ret;
1462
1463 read_lock(&tasklist_lock);
1464 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1465 read_unlock(&tasklist_lock);
1466
1467 return ret;
1468}
1469EXPORT_SYMBOL(kill_pgrp);
1470
1471int kill_pid(struct pid *pid, int sig, int priv)
1472{
1473 return kill_pid_info(sig, __si_special(priv), pid);
1474}
1475EXPORT_SYMBOL(kill_pid);
1476
1477/*
1478 * These functions support sending signals using preallocated sigqueue
1479 * structures. This is needed "because realtime applications cannot
1480 * afford to lose notifications of asynchronous events, like timer
1481 * expirations or I/O completions". In the case of POSIX Timers
1482 * we allocate the sigqueue structure from the timer_create. If this
1483 * allocation fails we are able to report the failure to the application
1484 * with an EAGAIN error.
1485 */
1486struct sigqueue *sigqueue_alloc(void)
1487{
1488 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1489
1490 if (q)
1491 q->flags |= SIGQUEUE_PREALLOC;
1492
1493 return q;
1494}
1495
1496void sigqueue_free(struct sigqueue *q)
1497{
1498 unsigned long flags;
1499 spinlock_t *lock = ¤t->sighand->siglock;
1500
1501 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1502 /*
1503 * We must hold ->siglock while testing q->list
1504 * to serialize with collect_signal() or with
1505 * __exit_signal()->flush_sigqueue().
1506 */
1507 spin_lock_irqsave(lock, flags);
1508 q->flags &= ~SIGQUEUE_PREALLOC;
1509 /*
1510 * If it is queued it will be freed when dequeued,
1511 * like the "regular" sigqueue.
1512 */
1513 if (!list_empty(&q->list))
1514 q = NULL;
1515 spin_unlock_irqrestore(lock, flags);
1516
1517 if (q)
1518 __sigqueue_free(q);
1519}
1520
1521int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1522{
1523 int sig = q->info.si_signo;
1524 struct sigpending *pending;
1525 unsigned long flags;
1526 int ret, result;
1527
1528 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1529
1530 ret = -1;
1531 if (!likely(lock_task_sighand(t, &flags)))
1532 goto ret;
1533
1534 ret = 1; /* the signal is ignored */
1535 result = TRACE_SIGNAL_IGNORED;
1536 if (!prepare_signal(sig, t, false))
1537 goto out;
1538
1539 ret = 0;
1540 if (unlikely(!list_empty(&q->list))) {
1541 /*
1542 * If an SI_TIMER entry is already queue just increment
1543 * the overrun count.
1544 */
1545 BUG_ON(q->info.si_code != SI_TIMER);
1546 q->info.si_overrun++;
1547 result = TRACE_SIGNAL_ALREADY_PENDING;
1548 goto out;
1549 }
1550 q->info.si_overrun = 0;
1551
1552 signalfd_notify(t, sig);
1553 pending = group ? &t->signal->shared_pending : &t->pending;
1554 list_add_tail(&q->list, &pending->list);
1555 sigaddset(&pending->signal, sig);
1556 complete_signal(sig, t, group);
1557 result = TRACE_SIGNAL_DELIVERED;
1558out:
1559 trace_signal_generate(sig, &q->info, t, group, result);
1560 unlock_task_sighand(t, &flags);
1561ret:
1562 return ret;
1563}
1564
1565/*
1566 * Let a parent know about the death of a child.
1567 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1568 *
1569 * Returns true if our parent ignored us and so we've switched to
1570 * self-reaping.
1571 */
1572bool do_notify_parent(struct task_struct *tsk, int sig)
1573{
1574 struct siginfo info;
1575 unsigned long flags;
1576 struct sighand_struct *psig;
1577 bool autoreap = false;
1578 cputime_t utime, stime;
1579
1580 BUG_ON(sig == -1);
1581
1582 /* do_notify_parent_cldstop should have been called instead. */
1583 BUG_ON(task_is_stopped_or_traced(tsk));
1584
1585 BUG_ON(!tsk->ptrace &&
1586 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1587
1588 if (sig != SIGCHLD) {
1589 /*
1590 * This is only possible if parent == real_parent.
1591 * Check if it has changed security domain.
1592 */
1593 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1594 sig = SIGCHLD;
1595 }
1596
1597 info.si_signo = sig;
1598 info.si_errno = 0;
1599 /*
1600 * We are under tasklist_lock here so our parent is tied to
1601 * us and cannot change.
1602 *
1603 * task_active_pid_ns will always return the same pid namespace
1604 * until a task passes through release_task.
1605 *
1606 * write_lock() currently calls preempt_disable() which is the
1607 * same as rcu_read_lock(), but according to Oleg, this is not
1608 * correct to rely on this
1609 */
1610 rcu_read_lock();
1611 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1612 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1613 task_uid(tsk));
1614 rcu_read_unlock();
1615
1616 task_cputime(tsk, &utime, &stime);
1617 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1618 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1619
1620 info.si_status = tsk->exit_code & 0x7f;
1621 if (tsk->exit_code & 0x80)
1622 info.si_code = CLD_DUMPED;
1623 else if (tsk->exit_code & 0x7f)
1624 info.si_code = CLD_KILLED;
1625 else {
1626 info.si_code = CLD_EXITED;
1627 info.si_status = tsk->exit_code >> 8;
1628 }
1629
1630 psig = tsk->parent->sighand;
1631 spin_lock_irqsave(&psig->siglock, flags);
1632 if (!tsk->ptrace && sig == SIGCHLD &&
1633 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1634 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1635 /*
1636 * We are exiting and our parent doesn't care. POSIX.1
1637 * defines special semantics for setting SIGCHLD to SIG_IGN
1638 * or setting the SA_NOCLDWAIT flag: we should be reaped
1639 * automatically and not left for our parent's wait4 call.
1640 * Rather than having the parent do it as a magic kind of
1641 * signal handler, we just set this to tell do_exit that we
1642 * can be cleaned up without becoming a zombie. Note that
1643 * we still call __wake_up_parent in this case, because a
1644 * blocked sys_wait4 might now return -ECHILD.
1645 *
1646 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1647 * is implementation-defined: we do (if you don't want
1648 * it, just use SIG_IGN instead).
1649 */
1650 autoreap = true;
1651 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1652 sig = 0;
1653 }
1654 if (valid_signal(sig) && sig)
1655 __group_send_sig_info(sig, &info, tsk->parent);
1656 __wake_up_parent(tsk, tsk->parent);
1657 spin_unlock_irqrestore(&psig->siglock, flags);
1658
1659 return autoreap;
1660}
1661
1662/**
1663 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1664 * @tsk: task reporting the state change
1665 * @for_ptracer: the notification is for ptracer
1666 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1667 *
1668 * Notify @tsk's parent that the stopped/continued state has changed. If
1669 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1670 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1671 *
1672 * CONTEXT:
1673 * Must be called with tasklist_lock at least read locked.
1674 */
1675static void do_notify_parent_cldstop(struct task_struct *tsk,
1676 bool for_ptracer, int why)
1677{
1678 struct siginfo info;
1679 unsigned long flags;
1680 struct task_struct *parent;
1681 struct sighand_struct *sighand;
1682 cputime_t utime, stime;
1683
1684 if (for_ptracer) {
1685 parent = tsk->parent;
1686 } else {
1687 tsk = tsk->group_leader;
1688 parent = tsk->real_parent;
1689 }
1690
1691 info.si_signo = SIGCHLD;
1692 info.si_errno = 0;
1693 /*
1694 * see comment in do_notify_parent() about the following 4 lines
1695 */
1696 rcu_read_lock();
1697 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1698 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1699 rcu_read_unlock();
1700
1701 task_cputime(tsk, &utime, &stime);
1702 info.si_utime = cputime_to_clock_t(utime);
1703 info.si_stime = cputime_to_clock_t(stime);
1704
1705 info.si_code = why;
1706 switch (why) {
1707 case CLD_CONTINUED:
1708 info.si_status = SIGCONT;
1709 break;
1710 case CLD_STOPPED:
1711 info.si_status = tsk->signal->group_exit_code & 0x7f;
1712 break;
1713 case CLD_TRAPPED:
1714 info.si_status = tsk->exit_code & 0x7f;
1715 break;
1716 default:
1717 BUG();
1718 }
1719
1720 sighand = parent->sighand;
1721 spin_lock_irqsave(&sighand->siglock, flags);
1722 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1723 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1724 __group_send_sig_info(SIGCHLD, &info, parent);
1725 /*
1726 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1727 */
1728 __wake_up_parent(tsk, parent);
1729 spin_unlock_irqrestore(&sighand->siglock, flags);
1730}
1731
1732static inline int may_ptrace_stop(void)
1733{
1734 if (!likely(current->ptrace))
1735 return 0;
1736 /*
1737 * Are we in the middle of do_coredump?
1738 * If so and our tracer is also part of the coredump stopping
1739 * is a deadlock situation, and pointless because our tracer
1740 * is dead so don't allow us to stop.
1741 * If SIGKILL was already sent before the caller unlocked
1742 * ->siglock we must see ->core_state != NULL. Otherwise it
1743 * is safe to enter schedule().
1744 *
1745 * This is almost outdated, a task with the pending SIGKILL can't
1746 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1747 * after SIGKILL was already dequeued.
1748 */
1749 if (unlikely(current->mm->core_state) &&
1750 unlikely(current->mm == current->parent->mm))
1751 return 0;
1752
1753 return 1;
1754}
1755
1756/*
1757 * Return non-zero if there is a SIGKILL that should be waking us up.
1758 * Called with the siglock held.
1759 */
1760static int sigkill_pending(struct task_struct *tsk)
1761{
1762 return sigismember(&tsk->pending.signal, SIGKILL) ||
1763 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1764}
1765
1766/*
1767 * This must be called with current->sighand->siglock held.
1768 *
1769 * This should be the path for all ptrace stops.
1770 * We always set current->last_siginfo while stopped here.
1771 * That makes it a way to test a stopped process for
1772 * being ptrace-stopped vs being job-control-stopped.
1773 *
1774 * If we actually decide not to stop at all because the tracer
1775 * is gone, we keep current->exit_code unless clear_code.
1776 */
1777static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1778 __releases(¤t->sighand->siglock)
1779 __acquires(¤t->sighand->siglock)
1780{
1781 bool gstop_done = false;
1782
1783 if (arch_ptrace_stop_needed(exit_code, info)) {
1784 /*
1785 * The arch code has something special to do before a
1786 * ptrace stop. This is allowed to block, e.g. for faults
1787 * on user stack pages. We can't keep the siglock while
1788 * calling arch_ptrace_stop, so we must release it now.
1789 * To preserve proper semantics, we must do this before
1790 * any signal bookkeeping like checking group_stop_count.
1791 * Meanwhile, a SIGKILL could come in before we retake the
1792 * siglock. That must prevent us from sleeping in TASK_TRACED.
1793 * So after regaining the lock, we must check for SIGKILL.
1794 */
1795 spin_unlock_irq(¤t->sighand->siglock);
1796 arch_ptrace_stop(exit_code, info);
1797 spin_lock_irq(¤t->sighand->siglock);
1798 if (sigkill_pending(current))
1799 return;
1800 }
1801
1802 /*
1803 * We're committing to trapping. TRACED should be visible before
1804 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1805 * Also, transition to TRACED and updates to ->jobctl should be
1806 * atomic with respect to siglock and should be done after the arch
1807 * hook as siglock is released and regrabbed across it.
1808 */
1809 set_current_state(TASK_TRACED);
1810
1811 current->last_siginfo = info;
1812 current->exit_code = exit_code;
1813
1814 /*
1815 * If @why is CLD_STOPPED, we're trapping to participate in a group
1816 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
1817 * across siglock relocks since INTERRUPT was scheduled, PENDING
1818 * could be clear now. We act as if SIGCONT is received after
1819 * TASK_TRACED is entered - ignore it.
1820 */
1821 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1822 gstop_done = task_participate_group_stop(current);
1823
1824 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1825 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1826 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1827 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1828
1829 /* entering a trap, clear TRAPPING */
1830 task_clear_jobctl_trapping(current);
1831
1832 spin_unlock_irq(¤t->sighand->siglock);
1833 read_lock(&tasklist_lock);
1834 if (may_ptrace_stop()) {
1835 /*
1836 * Notify parents of the stop.
1837 *
1838 * While ptraced, there are two parents - the ptracer and
1839 * the real_parent of the group_leader. The ptracer should
1840 * know about every stop while the real parent is only
1841 * interested in the completion of group stop. The states
1842 * for the two don't interact with each other. Notify
1843 * separately unless they're gonna be duplicates.
1844 */
1845 do_notify_parent_cldstop(current, true, why);
1846 if (gstop_done && ptrace_reparented(current))
1847 do_notify_parent_cldstop(current, false, why);
1848
1849 /*
1850 * Don't want to allow preemption here, because
1851 * sys_ptrace() needs this task to be inactive.
1852 *
1853 * XXX: implement read_unlock_no_resched().
1854 */
1855 preempt_disable();
1856 read_unlock(&tasklist_lock);
1857 preempt_enable_no_resched();
1858 freezable_schedule();
1859 } else {
1860 /*
1861 * By the time we got the lock, our tracer went away.
1862 * Don't drop the lock yet, another tracer may come.
1863 *
1864 * If @gstop_done, the ptracer went away between group stop
1865 * completion and here. During detach, it would have set
1866 * JOBCTL_STOP_PENDING on us and we'll re-enter
1867 * TASK_STOPPED in do_signal_stop() on return, so notifying
1868 * the real parent of the group stop completion is enough.
1869 */
1870 if (gstop_done)
1871 do_notify_parent_cldstop(current, false, why);
1872
1873 /* tasklist protects us from ptrace_freeze_traced() */
1874 __set_current_state(TASK_RUNNING);
1875 if (clear_code)
1876 current->exit_code = 0;
1877 read_unlock(&tasklist_lock);
1878 }
1879
1880 /*
1881 * We are back. Now reacquire the siglock before touching
1882 * last_siginfo, so that we are sure to have synchronized with
1883 * any signal-sending on another CPU that wants to examine it.
1884 */
1885 spin_lock_irq(¤t->sighand->siglock);
1886 current->last_siginfo = NULL;
1887
1888 /* LISTENING can be set only during STOP traps, clear it */
1889 current->jobctl &= ~JOBCTL_LISTENING;
1890
1891 /*
1892 * Queued signals ignored us while we were stopped for tracing.
1893 * So check for any that we should take before resuming user mode.
1894 * This sets TIF_SIGPENDING, but never clears it.
1895 */
1896 recalc_sigpending_tsk(current);
1897}
1898
1899static void ptrace_do_notify(int signr, int exit_code, int why)
1900{
1901 siginfo_t info;
1902
1903 memset(&info, 0, sizeof info);
1904 info.si_signo = signr;
1905 info.si_code = exit_code;
1906 info.si_pid = task_pid_vnr(current);
1907 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1908
1909 /* Let the debugger run. */
1910 ptrace_stop(exit_code, why, 1, &info);
1911}
1912
1913void ptrace_notify(int exit_code)
1914{
1915 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1916 if (unlikely(current->task_works))
1917 task_work_run();
1918
1919 spin_lock_irq(¤t->sighand->siglock);
1920 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1921 spin_unlock_irq(¤t->sighand->siglock);
1922}
1923
1924/**
1925 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1926 * @signr: signr causing group stop if initiating
1927 *
1928 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1929 * and participate in it. If already set, participate in the existing
1930 * group stop. If participated in a group stop (and thus slept), %true is
1931 * returned with siglock released.
1932 *
1933 * If ptraced, this function doesn't handle stop itself. Instead,
1934 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1935 * untouched. The caller must ensure that INTERRUPT trap handling takes
1936 * places afterwards.
1937 *
1938 * CONTEXT:
1939 * Must be called with @current->sighand->siglock held, which is released
1940 * on %true return.
1941 *
1942 * RETURNS:
1943 * %false if group stop is already cancelled or ptrace trap is scheduled.
1944 * %true if participated in group stop.
1945 */
1946static bool do_signal_stop(int signr)
1947 __releases(¤t->sighand->siglock)
1948{
1949 struct signal_struct *sig = current->signal;
1950
1951 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1952 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1953 struct task_struct *t;
1954
1955 /* signr will be recorded in task->jobctl for retries */
1956 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1957
1958 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1959 unlikely(signal_group_exit(sig)))
1960 return false;
1961 /*
1962 * There is no group stop already in progress. We must
1963 * initiate one now.
1964 *
1965 * While ptraced, a task may be resumed while group stop is
1966 * still in effect and then receive a stop signal and
1967 * initiate another group stop. This deviates from the
1968 * usual behavior as two consecutive stop signals can't
1969 * cause two group stops when !ptraced. That is why we
1970 * also check !task_is_stopped(t) below.
1971 *
1972 * The condition can be distinguished by testing whether
1973 * SIGNAL_STOP_STOPPED is already set. Don't generate
1974 * group_exit_code in such case.
1975 *
1976 * This is not necessary for SIGNAL_STOP_CONTINUED because
1977 * an intervening stop signal is required to cause two
1978 * continued events regardless of ptrace.
1979 */
1980 if (!(sig->flags & SIGNAL_STOP_STOPPED))
1981 sig->group_exit_code = signr;
1982
1983 sig->group_stop_count = 0;
1984
1985 if (task_set_jobctl_pending(current, signr | gstop))
1986 sig->group_stop_count++;
1987
1988 t = current;
1989 while_each_thread(current, t) {
1990 /*
1991 * Setting state to TASK_STOPPED for a group
1992 * stop is always done with the siglock held,
1993 * so this check has no races.
1994 */
1995 if (!task_is_stopped(t) &&
1996 task_set_jobctl_pending(t, signr | gstop)) {
1997 sig->group_stop_count++;
1998 if (likely(!(t->ptrace & PT_SEIZED)))
1999 signal_wake_up(t, 0);
2000 else
2001 ptrace_trap_notify(t);
2002 }
2003 }
2004 }
2005
2006 if (likely(!current->ptrace)) {
2007 int notify = 0;
2008
2009 /*
2010 * If there are no other threads in the group, or if there
2011 * is a group stop in progress and we are the last to stop,
2012 * report to the parent.
2013 */
2014 if (task_participate_group_stop(current))
2015 notify = CLD_STOPPED;
2016
2017 __set_current_state(TASK_STOPPED);
2018 spin_unlock_irq(¤t->sighand->siglock);
2019
2020 /*
2021 * Notify the parent of the group stop completion. Because
2022 * we're not holding either the siglock or tasklist_lock
2023 * here, ptracer may attach inbetween; however, this is for
2024 * group stop and should always be delivered to the real
2025 * parent of the group leader. The new ptracer will get
2026 * its notification when this task transitions into
2027 * TASK_TRACED.
2028 */
2029 if (notify) {
2030 read_lock(&tasklist_lock);
2031 do_notify_parent_cldstop(current, false, notify);
2032 read_unlock(&tasklist_lock);
2033 }
2034
2035 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2036 freezable_schedule();
2037 return true;
2038 } else {
2039 /*
2040 * While ptraced, group stop is handled by STOP trap.
2041 * Schedule it and let the caller deal with it.
2042 */
2043 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2044 return false;
2045 }
2046}
2047
2048/**
2049 * do_jobctl_trap - take care of ptrace jobctl traps
2050 *
2051 * When PT_SEIZED, it's used for both group stop and explicit
2052 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2053 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2054 * the stop signal; otherwise, %SIGTRAP.
2055 *
2056 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2057 * number as exit_code and no siginfo.
2058 *
2059 * CONTEXT:
2060 * Must be called with @current->sighand->siglock held, which may be
2061 * released and re-acquired before returning with intervening sleep.
2062 */
2063static void do_jobctl_trap(void)
2064{
2065 struct signal_struct *signal = current->signal;
2066 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2067
2068 if (current->ptrace & PT_SEIZED) {
2069 if (!signal->group_stop_count &&
2070 !(signal->flags & SIGNAL_STOP_STOPPED))
2071 signr = SIGTRAP;
2072 WARN_ON_ONCE(!signr);
2073 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2074 CLD_STOPPED);
2075 } else {
2076 WARN_ON_ONCE(!signr);
2077 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2078 current->exit_code = 0;
2079 }
2080}
2081
2082static int ptrace_signal(int signr, siginfo_t *info)
2083{
2084 ptrace_signal_deliver();
2085 /*
2086 * We do not check sig_kernel_stop(signr) but set this marker
2087 * unconditionally because we do not know whether debugger will
2088 * change signr. This flag has no meaning unless we are going
2089 * to stop after return from ptrace_stop(). In this case it will
2090 * be checked in do_signal_stop(), we should only stop if it was
2091 * not cleared by SIGCONT while we were sleeping. See also the
2092 * comment in dequeue_signal().
2093 */
2094 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2095 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2096
2097 /* We're back. Did the debugger cancel the sig? */
2098 signr = current->exit_code;
2099 if (signr == 0)
2100 return signr;
2101
2102 current->exit_code = 0;
2103
2104 /*
2105 * Update the siginfo structure if the signal has
2106 * changed. If the debugger wanted something
2107 * specific in the siginfo structure then it should
2108 * have updated *info via PTRACE_SETSIGINFO.
2109 */
2110 if (signr != info->si_signo) {
2111 info->si_signo = signr;
2112 info->si_errno = 0;
2113 info->si_code = SI_USER;
2114 rcu_read_lock();
2115 info->si_pid = task_pid_vnr(current->parent);
2116 info->si_uid = from_kuid_munged(current_user_ns(),
2117 task_uid(current->parent));
2118 rcu_read_unlock();
2119 }
2120
2121 /* If the (new) signal is now blocked, requeue it. */
2122 if (sigismember(¤t->blocked, signr)) {
2123 specific_send_sig_info(signr, info, current);
2124 signr = 0;
2125 }
2126
2127 return signr;
2128}
2129
2130int get_signal(struct ksignal *ksig)
2131{
2132 struct sighand_struct *sighand = current->sighand;
2133 struct signal_struct *signal = current->signal;
2134 int signr;
2135
2136 if (unlikely(current->task_works))
2137 task_work_run();
2138
2139 if (unlikely(uprobe_deny_signal()))
2140 return 0;
2141
2142 /*
2143 * Do this once, we can't return to user-mode if freezing() == T.
2144 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2145 * thus do not need another check after return.
2146 */
2147 try_to_freeze();
2148
2149relock:
2150 spin_lock_irq(&sighand->siglock);
2151 /*
2152 * Every stopped thread goes here after wakeup. Check to see if
2153 * we should notify the parent, prepare_signal(SIGCONT) encodes
2154 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2155 */
2156 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2157 int why;
2158
2159 if (signal->flags & SIGNAL_CLD_CONTINUED)
2160 why = CLD_CONTINUED;
2161 else
2162 why = CLD_STOPPED;
2163
2164 signal->flags &= ~SIGNAL_CLD_MASK;
2165
2166 spin_unlock_irq(&sighand->siglock);
2167
2168 /*
2169 * Notify the parent that we're continuing. This event is
2170 * always per-process and doesn't make whole lot of sense
2171 * for ptracers, who shouldn't consume the state via
2172 * wait(2) either, but, for backward compatibility, notify
2173 * the ptracer of the group leader too unless it's gonna be
2174 * a duplicate.
2175 */
2176 read_lock(&tasklist_lock);
2177 do_notify_parent_cldstop(current, false, why);
2178
2179 if (ptrace_reparented(current->group_leader))
2180 do_notify_parent_cldstop(current->group_leader,
2181 true, why);
2182 read_unlock(&tasklist_lock);
2183
2184 goto relock;
2185 }
2186
2187 for (;;) {
2188 struct k_sigaction *ka;
2189
2190 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2191 do_signal_stop(0))
2192 goto relock;
2193
2194 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2195 do_jobctl_trap();
2196 spin_unlock_irq(&sighand->siglock);
2197 goto relock;
2198 }
2199
2200 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2201
2202 if (!signr)
2203 break; /* will return 0 */
2204
2205 if (unlikely(current->ptrace) && signr != SIGKILL) {
2206 signr = ptrace_signal(signr, &ksig->info);
2207 if (!signr)
2208 continue;
2209 }
2210
2211 ka = &sighand->action[signr-1];
2212
2213 /* Trace actually delivered signals. */
2214 trace_signal_deliver(signr, &ksig->info, ka);
2215
2216 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2217 continue;
2218 if (ka->sa.sa_handler != SIG_DFL) {
2219 /* Run the handler. */
2220 ksig->ka = *ka;
2221
2222 if (ka->sa.sa_flags & SA_ONESHOT)
2223 ka->sa.sa_handler = SIG_DFL;
2224
2225 break; /* will return non-zero "signr" value */
2226 }
2227
2228 /*
2229 * Now we are doing the default action for this signal.
2230 */
2231 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2232 continue;
2233
2234 /*
2235 * Global init gets no signals it doesn't want.
2236 * Container-init gets no signals it doesn't want from same
2237 * container.
2238 *
2239 * Note that if global/container-init sees a sig_kernel_only()
2240 * signal here, the signal must have been generated internally
2241 * or must have come from an ancestor namespace. In either
2242 * case, the signal cannot be dropped.
2243 */
2244 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2245 !sig_kernel_only(signr))
2246 continue;
2247
2248 if (sig_kernel_stop(signr)) {
2249 /*
2250 * The default action is to stop all threads in
2251 * the thread group. The job control signals
2252 * do nothing in an orphaned pgrp, but SIGSTOP
2253 * always works. Note that siglock needs to be
2254 * dropped during the call to is_orphaned_pgrp()
2255 * because of lock ordering with tasklist_lock.
2256 * This allows an intervening SIGCONT to be posted.
2257 * We need to check for that and bail out if necessary.
2258 */
2259 if (signr != SIGSTOP) {
2260 spin_unlock_irq(&sighand->siglock);
2261
2262 /* signals can be posted during this window */
2263
2264 if (is_current_pgrp_orphaned())
2265 goto relock;
2266
2267 spin_lock_irq(&sighand->siglock);
2268 }
2269
2270 if (likely(do_signal_stop(ksig->info.si_signo))) {
2271 /* It released the siglock. */
2272 goto relock;
2273 }
2274
2275 /*
2276 * We didn't actually stop, due to a race
2277 * with SIGCONT or something like that.
2278 */
2279 continue;
2280 }
2281
2282 spin_unlock_irq(&sighand->siglock);
2283
2284 /*
2285 * Anything else is fatal, maybe with a core dump.
2286 */
2287 current->flags |= PF_SIGNALED;
2288
2289 if (sig_kernel_coredump(signr)) {
2290 if (print_fatal_signals)
2291 print_fatal_signal(ksig->info.si_signo);
2292 proc_coredump_connector(current);
2293 /*
2294 * If it was able to dump core, this kills all
2295 * other threads in the group and synchronizes with
2296 * their demise. If we lost the race with another
2297 * thread getting here, it set group_exit_code
2298 * first and our do_group_exit call below will use
2299 * that value and ignore the one we pass it.
2300 */
2301 do_coredump(&ksig->info);
2302 }
2303
2304 /*
2305 * Death signals, no core dump.
2306 */
2307 do_group_exit(ksig->info.si_signo);
2308 /* NOTREACHED */
2309 }
2310 spin_unlock_irq(&sighand->siglock);
2311
2312 ksig->sig = signr;
2313 return ksig->sig > 0;
2314}
2315
2316/**
2317 * signal_delivered -
2318 * @ksig: kernel signal struct
2319 * @stepping: nonzero if debugger single-step or block-step in use
2320 *
2321 * This function should be called when a signal has successfully been
2322 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2323 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2324 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2325 */
2326static void signal_delivered(struct ksignal *ksig, int stepping)
2327{
2328 sigset_t blocked;
2329
2330 /* A signal was successfully delivered, and the
2331 saved sigmask was stored on the signal frame,
2332 and will be restored by sigreturn. So we can
2333 simply clear the restore sigmask flag. */
2334 clear_restore_sigmask();
2335
2336 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2337 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2338 sigaddset(&blocked, ksig->sig);
2339 set_current_blocked(&blocked);
2340 tracehook_signal_handler(stepping);
2341}
2342
2343void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2344{
2345 if (failed)
2346 force_sigsegv(ksig->sig, current);
2347 else
2348 signal_delivered(ksig, stepping);
2349}
2350
2351/*
2352 * It could be that complete_signal() picked us to notify about the
2353 * group-wide signal. Other threads should be notified now to take
2354 * the shared signals in @which since we will not.
2355 */
2356static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2357{
2358 sigset_t retarget;
2359 struct task_struct *t;
2360
2361 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2362 if (sigisemptyset(&retarget))
2363 return;
2364
2365 t = tsk;
2366 while_each_thread(tsk, t) {
2367 if (t->flags & PF_EXITING)
2368 continue;
2369
2370 if (!has_pending_signals(&retarget, &t->blocked))
2371 continue;
2372 /* Remove the signals this thread can handle. */
2373 sigandsets(&retarget, &retarget, &t->blocked);
2374
2375 if (!signal_pending(t))
2376 signal_wake_up(t, 0);
2377
2378 if (sigisemptyset(&retarget))
2379 break;
2380 }
2381}
2382
2383void exit_signals(struct task_struct *tsk)
2384{
2385 int group_stop = 0;
2386 sigset_t unblocked;
2387
2388 /*
2389 * @tsk is about to have PF_EXITING set - lock out users which
2390 * expect stable threadgroup.
2391 */
2392 threadgroup_change_begin(tsk);
2393
2394 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2395 tsk->flags |= PF_EXITING;
2396 threadgroup_change_end(tsk);
2397 return;
2398 }
2399
2400 spin_lock_irq(&tsk->sighand->siglock);
2401 /*
2402 * From now this task is not visible for group-wide signals,
2403 * see wants_signal(), do_signal_stop().
2404 */
2405 tsk->flags |= PF_EXITING;
2406
2407 threadgroup_change_end(tsk);
2408
2409 if (!signal_pending(tsk))
2410 goto out;
2411
2412 unblocked = tsk->blocked;
2413 signotset(&unblocked);
2414 retarget_shared_pending(tsk, &unblocked);
2415
2416 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2417 task_participate_group_stop(tsk))
2418 group_stop = CLD_STOPPED;
2419out:
2420 spin_unlock_irq(&tsk->sighand->siglock);
2421
2422 /*
2423 * If group stop has completed, deliver the notification. This
2424 * should always go to the real parent of the group leader.
2425 */
2426 if (unlikely(group_stop)) {
2427 read_lock(&tasklist_lock);
2428 do_notify_parent_cldstop(tsk, false, group_stop);
2429 read_unlock(&tasklist_lock);
2430 }
2431}
2432
2433EXPORT_SYMBOL(recalc_sigpending);
2434EXPORT_SYMBOL_GPL(dequeue_signal);
2435EXPORT_SYMBOL(flush_signals);
2436EXPORT_SYMBOL(force_sig);
2437EXPORT_SYMBOL(send_sig);
2438EXPORT_SYMBOL(send_sig_info);
2439EXPORT_SYMBOL(sigprocmask);
2440
2441/*
2442 * System call entry points.
2443 */
2444
2445/**
2446 * sys_restart_syscall - restart a system call
2447 */
2448SYSCALL_DEFINE0(restart_syscall)
2449{
2450 struct restart_block *restart = ¤t->restart_block;
2451 return restart->fn(restart);
2452}
2453
2454long do_no_restart_syscall(struct restart_block *param)
2455{
2456 return -EINTR;
2457}
2458
2459static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2460{
2461 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2462 sigset_t newblocked;
2463 /* A set of now blocked but previously unblocked signals. */
2464 sigandnsets(&newblocked, newset, ¤t->blocked);
2465 retarget_shared_pending(tsk, &newblocked);
2466 }
2467 tsk->blocked = *newset;
2468 recalc_sigpending();
2469}
2470
2471/**
2472 * set_current_blocked - change current->blocked mask
2473 * @newset: new mask
2474 *
2475 * It is wrong to change ->blocked directly, this helper should be used
2476 * to ensure the process can't miss a shared signal we are going to block.
2477 */
2478void set_current_blocked(sigset_t *newset)
2479{
2480 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2481 __set_current_blocked(newset);
2482}
2483
2484void __set_current_blocked(const sigset_t *newset)
2485{
2486 struct task_struct *tsk = current;
2487
2488 spin_lock_irq(&tsk->sighand->siglock);
2489 __set_task_blocked(tsk, newset);
2490 spin_unlock_irq(&tsk->sighand->siglock);
2491}
2492
2493/*
2494 * This is also useful for kernel threads that want to temporarily
2495 * (or permanently) block certain signals.
2496 *
2497 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2498 * interface happily blocks "unblockable" signals like SIGKILL
2499 * and friends.
2500 */
2501int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2502{
2503 struct task_struct *tsk = current;
2504 sigset_t newset;
2505
2506 /* Lockless, only current can change ->blocked, never from irq */
2507 if (oldset)
2508 *oldset = tsk->blocked;
2509
2510 switch (how) {
2511 case SIG_BLOCK:
2512 sigorsets(&newset, &tsk->blocked, set);
2513 break;
2514 case SIG_UNBLOCK:
2515 sigandnsets(&newset, &tsk->blocked, set);
2516 break;
2517 case SIG_SETMASK:
2518 newset = *set;
2519 break;
2520 default:
2521 return -EINVAL;
2522 }
2523
2524 __set_current_blocked(&newset);
2525 return 0;
2526}
2527
2528/**
2529 * sys_rt_sigprocmask - change the list of currently blocked signals
2530 * @how: whether to add, remove, or set signals
2531 * @nset: stores pending signals
2532 * @oset: previous value of signal mask if non-null
2533 * @sigsetsize: size of sigset_t type
2534 */
2535SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2536 sigset_t __user *, oset, size_t, sigsetsize)
2537{
2538 sigset_t old_set, new_set;
2539 int error;
2540
2541 /* XXX: Don't preclude handling different sized sigset_t's. */
2542 if (sigsetsize != sizeof(sigset_t))
2543 return -EINVAL;
2544
2545 old_set = current->blocked;
2546
2547 if (nset) {
2548 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2549 return -EFAULT;
2550 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2551
2552 error = sigprocmask(how, &new_set, NULL);
2553 if (error)
2554 return error;
2555 }
2556
2557 if (oset) {
2558 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2559 return -EFAULT;
2560 }
2561
2562 return 0;
2563}
2564
2565#ifdef CONFIG_COMPAT
2566COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2567 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2568{
2569#ifdef __BIG_ENDIAN
2570 sigset_t old_set = current->blocked;
2571
2572 /* XXX: Don't preclude handling different sized sigset_t's. */
2573 if (sigsetsize != sizeof(sigset_t))
2574 return -EINVAL;
2575
2576 if (nset) {
2577 compat_sigset_t new32;
2578 sigset_t new_set;
2579 int error;
2580 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2581 return -EFAULT;
2582
2583 sigset_from_compat(&new_set, &new32);
2584 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2585
2586 error = sigprocmask(how, &new_set, NULL);
2587 if (error)
2588 return error;
2589 }
2590 if (oset) {
2591 compat_sigset_t old32;
2592 sigset_to_compat(&old32, &old_set);
2593 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2594 return -EFAULT;
2595 }
2596 return 0;
2597#else
2598 return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2599 (sigset_t __user *)oset, sigsetsize);
2600#endif
2601}
2602#endif
2603
2604static int do_sigpending(void *set, unsigned long sigsetsize)
2605{
2606 if (sigsetsize > sizeof(sigset_t))
2607 return -EINVAL;
2608
2609 spin_lock_irq(¤t->sighand->siglock);
2610 sigorsets(set, ¤t->pending.signal,
2611 ¤t->signal->shared_pending.signal);
2612 spin_unlock_irq(¤t->sighand->siglock);
2613
2614 /* Outside the lock because only this thread touches it. */
2615 sigandsets(set, ¤t->blocked, set);
2616 return 0;
2617}
2618
2619/**
2620 * sys_rt_sigpending - examine a pending signal that has been raised
2621 * while blocked
2622 * @uset: stores pending signals
2623 * @sigsetsize: size of sigset_t type or larger
2624 */
2625SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2626{
2627 sigset_t set;
2628 int err = do_sigpending(&set, sigsetsize);
2629 if (!err && copy_to_user(uset, &set, sigsetsize))
2630 err = -EFAULT;
2631 return err;
2632}
2633
2634#ifdef CONFIG_COMPAT
2635COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2636 compat_size_t, sigsetsize)
2637{
2638#ifdef __BIG_ENDIAN
2639 sigset_t set;
2640 int err = do_sigpending(&set, sigsetsize);
2641 if (!err) {
2642 compat_sigset_t set32;
2643 sigset_to_compat(&set32, &set);
2644 /* we can get here only if sigsetsize <= sizeof(set) */
2645 if (copy_to_user(uset, &set32, sigsetsize))
2646 err = -EFAULT;
2647 }
2648 return err;
2649#else
2650 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2651#endif
2652}
2653#endif
2654
2655#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2656
2657int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2658{
2659 int err;
2660
2661 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2662 return -EFAULT;
2663 if (from->si_code < 0)
2664 return __copy_to_user(to, from, sizeof(siginfo_t))
2665 ? -EFAULT : 0;
2666 /*
2667 * If you change siginfo_t structure, please be sure
2668 * this code is fixed accordingly.
2669 * Please remember to update the signalfd_copyinfo() function
2670 * inside fs/signalfd.c too, in case siginfo_t changes.
2671 * It should never copy any pad contained in the structure
2672 * to avoid security leaks, but must copy the generic
2673 * 3 ints plus the relevant union member.
2674 */
2675 err = __put_user(from->si_signo, &to->si_signo);
2676 err |= __put_user(from->si_errno, &to->si_errno);
2677 err |= __put_user((short)from->si_code, &to->si_code);
2678 switch (from->si_code & __SI_MASK) {
2679 case __SI_KILL:
2680 err |= __put_user(from->si_pid, &to->si_pid);
2681 err |= __put_user(from->si_uid, &to->si_uid);
2682 break;
2683 case __SI_TIMER:
2684 err |= __put_user(from->si_tid, &to->si_tid);
2685 err |= __put_user(from->si_overrun, &to->si_overrun);
2686 err |= __put_user(from->si_ptr, &to->si_ptr);
2687 break;
2688 case __SI_POLL:
2689 err |= __put_user(from->si_band, &to->si_band);
2690 err |= __put_user(from->si_fd, &to->si_fd);
2691 break;
2692 case __SI_FAULT:
2693 err |= __put_user(from->si_addr, &to->si_addr);
2694#ifdef __ARCH_SI_TRAPNO
2695 err |= __put_user(from->si_trapno, &to->si_trapno);
2696#endif
2697#ifdef BUS_MCEERR_AO
2698 /*
2699 * Other callers might not initialize the si_lsb field,
2700 * so check explicitly for the right codes here.
2701 */
2702 if (from->si_signo == SIGBUS &&
2703 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2704 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2705#endif
2706#ifdef SEGV_BNDERR
2707 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2708 err |= __put_user(from->si_lower, &to->si_lower);
2709 err |= __put_user(from->si_upper, &to->si_upper);
2710 }
2711#endif
2712#ifdef SEGV_PKUERR
2713 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2714 err |= __put_user(from->si_pkey, &to->si_pkey);
2715#endif
2716 break;
2717 case __SI_CHLD:
2718 err |= __put_user(from->si_pid, &to->si_pid);
2719 err |= __put_user(from->si_uid, &to->si_uid);
2720 err |= __put_user(from->si_status, &to->si_status);
2721 err |= __put_user(from->si_utime, &to->si_utime);
2722 err |= __put_user(from->si_stime, &to->si_stime);
2723 break;
2724 case __SI_RT: /* This is not generated by the kernel as of now. */
2725 case __SI_MESGQ: /* But this is */
2726 err |= __put_user(from->si_pid, &to->si_pid);
2727 err |= __put_user(from->si_uid, &to->si_uid);
2728 err |= __put_user(from->si_ptr, &to->si_ptr);
2729 break;
2730#ifdef __ARCH_SIGSYS
2731 case __SI_SYS:
2732 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2733 err |= __put_user(from->si_syscall, &to->si_syscall);
2734 err |= __put_user(from->si_arch, &to->si_arch);
2735 break;
2736#endif
2737 default: /* this is just in case for now ... */
2738 err |= __put_user(from->si_pid, &to->si_pid);
2739 err |= __put_user(from->si_uid, &to->si_uid);
2740 break;
2741 }
2742 return err;
2743}
2744
2745#endif
2746
2747/**
2748 * do_sigtimedwait - wait for queued signals specified in @which
2749 * @which: queued signals to wait for
2750 * @info: if non-null, the signal's siginfo is returned here
2751 * @ts: upper bound on process time suspension
2752 */
2753int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2754 const struct timespec *ts)
2755{
2756 struct task_struct *tsk = current;
2757 long timeout = MAX_SCHEDULE_TIMEOUT;
2758 sigset_t mask = *which;
2759 int sig;
2760
2761 if (ts) {
2762 if (!timespec_valid(ts))
2763 return -EINVAL;
2764 timeout = timespec_to_jiffies(ts);
2765 /*
2766 * We can be close to the next tick, add another one
2767 * to ensure we will wait at least the time asked for.
2768 */
2769 if (ts->tv_sec || ts->tv_nsec)
2770 timeout++;
2771 }
2772
2773 /*
2774 * Invert the set of allowed signals to get those we want to block.
2775 */
2776 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2777 signotset(&mask);
2778
2779 spin_lock_irq(&tsk->sighand->siglock);
2780 sig = dequeue_signal(tsk, &mask, info);
2781 if (!sig && timeout) {
2782 /*
2783 * None ready, temporarily unblock those we're interested
2784 * while we are sleeping in so that we'll be awakened when
2785 * they arrive. Unblocking is always fine, we can avoid
2786 * set_current_blocked().
2787 */
2788 tsk->real_blocked = tsk->blocked;
2789 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2790 recalc_sigpending();
2791 spin_unlock_irq(&tsk->sighand->siglock);
2792
2793 timeout = freezable_schedule_timeout_interruptible(timeout);
2794
2795 spin_lock_irq(&tsk->sighand->siglock);
2796 __set_task_blocked(tsk, &tsk->real_blocked);
2797 sigemptyset(&tsk->real_blocked);
2798 sig = dequeue_signal(tsk, &mask, info);
2799 }
2800 spin_unlock_irq(&tsk->sighand->siglock);
2801
2802 if (sig)
2803 return sig;
2804 return timeout ? -EINTR : -EAGAIN;
2805}
2806
2807/**
2808 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
2809 * in @uthese
2810 * @uthese: queued signals to wait for
2811 * @uinfo: if non-null, the signal's siginfo is returned here
2812 * @uts: upper bound on process time suspension
2813 * @sigsetsize: size of sigset_t type
2814 */
2815SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2816 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2817 size_t, sigsetsize)
2818{
2819 sigset_t these;
2820 struct timespec ts;
2821 siginfo_t info;
2822 int ret;
2823
2824 /* XXX: Don't preclude handling different sized sigset_t's. */
2825 if (sigsetsize != sizeof(sigset_t))
2826 return -EINVAL;
2827
2828 if (copy_from_user(&these, uthese, sizeof(these)))
2829 return -EFAULT;
2830
2831 if (uts) {
2832 if (copy_from_user(&ts, uts, sizeof(ts)))
2833 return -EFAULT;
2834 }
2835
2836 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2837
2838 if (ret > 0 && uinfo) {
2839 if (copy_siginfo_to_user(uinfo, &info))
2840 ret = -EFAULT;
2841 }
2842
2843 return ret;
2844}
2845
2846/**
2847 * sys_kill - send a signal to a process
2848 * @pid: the PID of the process
2849 * @sig: signal to be sent
2850 */
2851SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2852{
2853 struct siginfo info;
2854
2855 info.si_signo = sig;
2856 info.si_errno = 0;
2857 info.si_code = SI_USER;
2858 info.si_pid = task_tgid_vnr(current);
2859 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2860
2861 return kill_something_info(sig, &info, pid);
2862}
2863
2864static int
2865do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2866{
2867 struct task_struct *p;
2868 int error = -ESRCH;
2869
2870 rcu_read_lock();
2871 p = find_task_by_vpid(pid);
2872 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2873 error = check_kill_permission(sig, info, p);
2874 /*
2875 * The null signal is a permissions and process existence
2876 * probe. No signal is actually delivered.
2877 */
2878 if (!error && sig) {
2879 error = do_send_sig_info(sig, info, p, false);
2880 /*
2881 * If lock_task_sighand() failed we pretend the task
2882 * dies after receiving the signal. The window is tiny,
2883 * and the signal is private anyway.
2884 */
2885 if (unlikely(error == -ESRCH))
2886 error = 0;
2887 }
2888 }
2889 rcu_read_unlock();
2890
2891 return error;
2892}
2893
2894static int do_tkill(pid_t tgid, pid_t pid, int sig)
2895{
2896 struct siginfo info = {};
2897
2898 info.si_signo = sig;
2899 info.si_errno = 0;
2900 info.si_code = SI_TKILL;
2901 info.si_pid = task_tgid_vnr(current);
2902 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2903
2904 return do_send_specific(tgid, pid, sig, &info);
2905}
2906
2907/**
2908 * sys_tgkill - send signal to one specific thread
2909 * @tgid: the thread group ID of the thread
2910 * @pid: the PID of the thread
2911 * @sig: signal to be sent
2912 *
2913 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2914 * exists but it's not belonging to the target process anymore. This
2915 * method solves the problem of threads exiting and PIDs getting reused.
2916 */
2917SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2918{
2919 /* This is only valid for single tasks */
2920 if (pid <= 0 || tgid <= 0)
2921 return -EINVAL;
2922
2923 return do_tkill(tgid, pid, sig);
2924}
2925
2926/**
2927 * sys_tkill - send signal to one specific task
2928 * @pid: the PID of the task
2929 * @sig: signal to be sent
2930 *
2931 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2932 */
2933SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2934{
2935 /* This is only valid for single tasks */
2936 if (pid <= 0)
2937 return -EINVAL;
2938
2939 return do_tkill(0, pid, sig);
2940}
2941
2942static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2943{
2944 /* Not even root can pretend to send signals from the kernel.
2945 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2946 */
2947 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2948 (task_pid_vnr(current) != pid))
2949 return -EPERM;
2950
2951 info->si_signo = sig;
2952
2953 /* POSIX.1b doesn't mention process groups. */
2954 return kill_proc_info(sig, info, pid);
2955}
2956
2957/**
2958 * sys_rt_sigqueueinfo - send signal information to a signal
2959 * @pid: the PID of the thread
2960 * @sig: signal to be sent
2961 * @uinfo: signal info to be sent
2962 */
2963SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
2964 siginfo_t __user *, uinfo)
2965{
2966 siginfo_t info;
2967 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2968 return -EFAULT;
2969 return do_rt_sigqueueinfo(pid, sig, &info);
2970}
2971
2972#ifdef CONFIG_COMPAT
2973COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
2974 compat_pid_t, pid,
2975 int, sig,
2976 struct compat_siginfo __user *, uinfo)
2977{
2978 siginfo_t info = {};
2979 int ret = copy_siginfo_from_user32(&info, uinfo);
2980 if (unlikely(ret))
2981 return ret;
2982 return do_rt_sigqueueinfo(pid, sig, &info);
2983}
2984#endif
2985
2986static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2987{
2988 /* This is only valid for single tasks */
2989 if (pid <= 0 || tgid <= 0)
2990 return -EINVAL;
2991
2992 /* Not even root can pretend to send signals from the kernel.
2993 * Nor can they impersonate a kill()/tgkill(), which adds source info.
2994 */
2995 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2996 (task_pid_vnr(current) != pid))
2997 return -EPERM;
2998
2999 info->si_signo = sig;
3000
3001 return do_send_specific(tgid, pid, sig, info);
3002}
3003
3004SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3005 siginfo_t __user *, uinfo)
3006{
3007 siginfo_t info;
3008
3009 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3010 return -EFAULT;
3011
3012 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3013}
3014
3015#ifdef CONFIG_COMPAT
3016COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3017 compat_pid_t, tgid,
3018 compat_pid_t, pid,
3019 int, sig,
3020 struct compat_siginfo __user *, uinfo)
3021{
3022 siginfo_t info = {};
3023
3024 if (copy_siginfo_from_user32(&info, uinfo))
3025 return -EFAULT;
3026 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3027}
3028#endif
3029
3030/*
3031 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3032 */
3033void kernel_sigaction(int sig, __sighandler_t action)
3034{
3035 spin_lock_irq(¤t->sighand->siglock);
3036 current->sighand->action[sig - 1].sa.sa_handler = action;
3037 if (action == SIG_IGN) {
3038 sigset_t mask;
3039
3040 sigemptyset(&mask);
3041 sigaddset(&mask, sig);
3042
3043 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3044 flush_sigqueue_mask(&mask, ¤t->pending);
3045 recalc_sigpending();
3046 }
3047 spin_unlock_irq(¤t->sighand->siglock);
3048}
3049EXPORT_SYMBOL(kernel_sigaction);
3050
3051int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3052{
3053 struct task_struct *p = current, *t;
3054 struct k_sigaction *k;
3055 sigset_t mask;
3056
3057 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3058 return -EINVAL;
3059
3060 k = &p->sighand->action[sig-1];
3061
3062 spin_lock_irq(&p->sighand->siglock);
3063 if (oact)
3064 *oact = *k;
3065
3066 if (act) {
3067 sigdelsetmask(&act->sa.sa_mask,
3068 sigmask(SIGKILL) | sigmask(SIGSTOP));
3069 *k = *act;
3070 /*
3071 * POSIX 3.3.1.3:
3072 * "Setting a signal action to SIG_IGN for a signal that is
3073 * pending shall cause the pending signal to be discarded,
3074 * whether or not it is blocked."
3075 *
3076 * "Setting a signal action to SIG_DFL for a signal that is
3077 * pending and whose default action is to ignore the signal
3078 * (for example, SIGCHLD), shall cause the pending signal to
3079 * be discarded, whether or not it is blocked"
3080 */
3081 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3082 sigemptyset(&mask);
3083 sigaddset(&mask, sig);
3084 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3085 for_each_thread(p, t)
3086 flush_sigqueue_mask(&mask, &t->pending);
3087 }
3088 }
3089
3090 spin_unlock_irq(&p->sighand->siglock);
3091 return 0;
3092}
3093
3094static int
3095do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3096{
3097 stack_t oss;
3098 int error;
3099
3100 oss.ss_sp = (void __user *) current->sas_ss_sp;
3101 oss.ss_size = current->sas_ss_size;
3102 oss.ss_flags = sas_ss_flags(sp);
3103
3104 if (uss) {
3105 void __user *ss_sp;
3106 size_t ss_size;
3107 int ss_flags;
3108
3109 error = -EFAULT;
3110 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3111 goto out;
3112 error = __get_user(ss_sp, &uss->ss_sp) |
3113 __get_user(ss_flags, &uss->ss_flags) |
3114 __get_user(ss_size, &uss->ss_size);
3115 if (error)
3116 goto out;
3117
3118 error = -EPERM;
3119 if (on_sig_stack(sp))
3120 goto out;
3121
3122 error = -EINVAL;
3123 /*
3124 * Note - this code used to test ss_flags incorrectly:
3125 * old code may have been written using ss_flags==0
3126 * to mean ss_flags==SS_ONSTACK (as this was the only
3127 * way that worked) - this fix preserves that older
3128 * mechanism.
3129 */
3130 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3131 goto out;
3132
3133 if (ss_flags == SS_DISABLE) {
3134 ss_size = 0;
3135 ss_sp = NULL;
3136 } else {
3137 error = -ENOMEM;
3138 if (ss_size < MINSIGSTKSZ)
3139 goto out;
3140 }
3141
3142 current->sas_ss_sp = (unsigned long) ss_sp;
3143 current->sas_ss_size = ss_size;
3144 }
3145
3146 error = 0;
3147 if (uoss) {
3148 error = -EFAULT;
3149 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3150 goto out;
3151 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3152 __put_user(oss.ss_size, &uoss->ss_size) |
3153 __put_user(oss.ss_flags, &uoss->ss_flags);
3154 }
3155
3156out:
3157 return error;
3158}
3159SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3160{
3161 return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3162}
3163
3164int restore_altstack(const stack_t __user *uss)
3165{
3166 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3167 /* squash all but EFAULT for now */
3168 return err == -EFAULT ? err : 0;
3169}
3170
3171int __save_altstack(stack_t __user *uss, unsigned long sp)
3172{
3173 struct task_struct *t = current;
3174 return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3175 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3176 __put_user(t->sas_ss_size, &uss->ss_size);
3177}
3178
3179#ifdef CONFIG_COMPAT
3180COMPAT_SYSCALL_DEFINE2(sigaltstack,
3181 const compat_stack_t __user *, uss_ptr,
3182 compat_stack_t __user *, uoss_ptr)
3183{
3184 stack_t uss, uoss;
3185 int ret;
3186 mm_segment_t seg;
3187
3188 if (uss_ptr) {
3189 compat_stack_t uss32;
3190
3191 memset(&uss, 0, sizeof(stack_t));
3192 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3193 return -EFAULT;
3194 uss.ss_sp = compat_ptr(uss32.ss_sp);
3195 uss.ss_flags = uss32.ss_flags;
3196 uss.ss_size = uss32.ss_size;
3197 }
3198 seg = get_fs();
3199 set_fs(KERNEL_DS);
3200 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3201 (stack_t __force __user *) &uoss,
3202 compat_user_stack_pointer());
3203 set_fs(seg);
3204 if (ret >= 0 && uoss_ptr) {
3205 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3206 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3207 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3208 __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3209 ret = -EFAULT;
3210 }
3211 return ret;
3212}
3213
3214int compat_restore_altstack(const compat_stack_t __user *uss)
3215{
3216 int err = compat_sys_sigaltstack(uss, NULL);
3217 /* squash all but -EFAULT for now */
3218 return err == -EFAULT ? err : 0;
3219}
3220
3221int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3222{
3223 struct task_struct *t = current;
3224 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3225 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3226 __put_user(t->sas_ss_size, &uss->ss_size);
3227}
3228#endif
3229
3230#ifdef __ARCH_WANT_SYS_SIGPENDING
3231
3232/**
3233 * sys_sigpending - examine pending signals
3234 * @set: where mask of pending signal is returned
3235 */
3236SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3237{
3238 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3239}
3240
3241#endif
3242
3243#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3244/**
3245 * sys_sigprocmask - examine and change blocked signals
3246 * @how: whether to add, remove, or set signals
3247 * @nset: signals to add or remove (if non-null)
3248 * @oset: previous value of signal mask if non-null
3249 *
3250 * Some platforms have their own version with special arguments;
3251 * others support only sys_rt_sigprocmask.
3252 */
3253
3254SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3255 old_sigset_t __user *, oset)
3256{
3257 old_sigset_t old_set, new_set;
3258 sigset_t new_blocked;
3259
3260 old_set = current->blocked.sig[0];
3261
3262 if (nset) {
3263 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3264 return -EFAULT;
3265
3266 new_blocked = current->blocked;
3267
3268 switch (how) {
3269 case SIG_BLOCK:
3270 sigaddsetmask(&new_blocked, new_set);
3271 break;
3272 case SIG_UNBLOCK:
3273 sigdelsetmask(&new_blocked, new_set);
3274 break;
3275 case SIG_SETMASK:
3276 new_blocked.sig[0] = new_set;
3277 break;
3278 default:
3279 return -EINVAL;
3280 }
3281
3282 set_current_blocked(&new_blocked);
3283 }
3284
3285 if (oset) {
3286 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3287 return -EFAULT;
3288 }
3289
3290 return 0;
3291}
3292#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3293
3294#ifndef CONFIG_ODD_RT_SIGACTION
3295/**
3296 * sys_rt_sigaction - alter an action taken by a process
3297 * @sig: signal to be sent
3298 * @act: new sigaction
3299 * @oact: used to save the previous sigaction
3300 * @sigsetsize: size of sigset_t type
3301 */
3302SYSCALL_DEFINE4(rt_sigaction, int, sig,
3303 const struct sigaction __user *, act,
3304 struct sigaction __user *, oact,
3305 size_t, sigsetsize)
3306{
3307 struct k_sigaction new_sa, old_sa;
3308 int ret = -EINVAL;
3309
3310 /* XXX: Don't preclude handling different sized sigset_t's. */
3311 if (sigsetsize != sizeof(sigset_t))
3312 goto out;
3313
3314 if (act) {
3315 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3316 return -EFAULT;
3317 }
3318
3319 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3320
3321 if (!ret && oact) {
3322 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3323 return -EFAULT;
3324 }
3325out:
3326 return ret;
3327}
3328#ifdef CONFIG_COMPAT
3329COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3330 const struct compat_sigaction __user *, act,
3331 struct compat_sigaction __user *, oact,
3332 compat_size_t, sigsetsize)
3333{
3334 struct k_sigaction new_ka, old_ka;
3335 compat_sigset_t mask;
3336#ifdef __ARCH_HAS_SA_RESTORER
3337 compat_uptr_t restorer;
3338#endif
3339 int ret;
3340
3341 /* XXX: Don't preclude handling different sized sigset_t's. */
3342 if (sigsetsize != sizeof(compat_sigset_t))
3343 return -EINVAL;
3344
3345 if (act) {
3346 compat_uptr_t handler;
3347 ret = get_user(handler, &act->sa_handler);
3348 new_ka.sa.sa_handler = compat_ptr(handler);
3349#ifdef __ARCH_HAS_SA_RESTORER
3350 ret |= get_user(restorer, &act->sa_restorer);
3351 new_ka.sa.sa_restorer = compat_ptr(restorer);
3352#endif
3353 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3354 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3355 if (ret)
3356 return -EFAULT;
3357 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3358 }
3359
3360 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3361 if (!ret && oact) {
3362 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3363 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3364 &oact->sa_handler);
3365 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3366 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3367#ifdef __ARCH_HAS_SA_RESTORER
3368 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3369 &oact->sa_restorer);
3370#endif
3371 }
3372 return ret;
3373}
3374#endif
3375#endif /* !CONFIG_ODD_RT_SIGACTION */
3376
3377#ifdef CONFIG_OLD_SIGACTION
3378SYSCALL_DEFINE3(sigaction, int, sig,
3379 const struct old_sigaction __user *, act,
3380 struct old_sigaction __user *, oact)
3381{
3382 struct k_sigaction new_ka, old_ka;
3383 int ret;
3384
3385 if (act) {
3386 old_sigset_t mask;
3387 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3388 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3389 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3390 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3391 __get_user(mask, &act->sa_mask))
3392 return -EFAULT;
3393#ifdef __ARCH_HAS_KA_RESTORER
3394 new_ka.ka_restorer = NULL;
3395#endif
3396 siginitset(&new_ka.sa.sa_mask, mask);
3397 }
3398
3399 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3400
3401 if (!ret && oact) {
3402 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3403 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3404 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3405 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3406 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3407 return -EFAULT;
3408 }
3409
3410 return ret;
3411}
3412#endif
3413#ifdef CONFIG_COMPAT_OLD_SIGACTION
3414COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3415 const struct compat_old_sigaction __user *, act,
3416 struct compat_old_sigaction __user *, oact)
3417{
3418 struct k_sigaction new_ka, old_ka;
3419 int ret;
3420 compat_old_sigset_t mask;
3421 compat_uptr_t handler, restorer;
3422
3423 if (act) {
3424 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3425 __get_user(handler, &act->sa_handler) ||
3426 __get_user(restorer, &act->sa_restorer) ||
3427 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3428 __get_user(mask, &act->sa_mask))
3429 return -EFAULT;
3430
3431#ifdef __ARCH_HAS_KA_RESTORER
3432 new_ka.ka_restorer = NULL;
3433#endif
3434 new_ka.sa.sa_handler = compat_ptr(handler);
3435 new_ka.sa.sa_restorer = compat_ptr(restorer);
3436 siginitset(&new_ka.sa.sa_mask, mask);
3437 }
3438
3439 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3440
3441 if (!ret && oact) {
3442 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3443 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3444 &oact->sa_handler) ||
3445 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3446 &oact->sa_restorer) ||
3447 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3448 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3449 return -EFAULT;
3450 }
3451 return ret;
3452}
3453#endif
3454
3455#ifdef CONFIG_SGETMASK_SYSCALL
3456
3457/*
3458 * For backwards compatibility. Functionality superseded by sigprocmask.
3459 */
3460SYSCALL_DEFINE0(sgetmask)
3461{
3462 /* SMP safe */
3463 return current->blocked.sig[0];
3464}
3465
3466SYSCALL_DEFINE1(ssetmask, int, newmask)
3467{
3468 int old = current->blocked.sig[0];
3469 sigset_t newset;
3470
3471 siginitset(&newset, newmask);
3472 set_current_blocked(&newset);
3473
3474 return old;
3475}
3476#endif /* CONFIG_SGETMASK_SYSCALL */
3477
3478#ifdef __ARCH_WANT_SYS_SIGNAL
3479/*
3480 * For backwards compatibility. Functionality superseded by sigaction.
3481 */
3482SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3483{
3484 struct k_sigaction new_sa, old_sa;
3485 int ret;
3486
3487 new_sa.sa.sa_handler = handler;
3488 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3489 sigemptyset(&new_sa.sa.sa_mask);
3490
3491 ret = do_sigaction(sig, &new_sa, &old_sa);
3492
3493 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3494}
3495#endif /* __ARCH_WANT_SYS_SIGNAL */
3496
3497#ifdef __ARCH_WANT_SYS_PAUSE
3498
3499SYSCALL_DEFINE0(pause)
3500{
3501 while (!signal_pending(current)) {
3502 __set_current_state(TASK_INTERRUPTIBLE);
3503 schedule();
3504 }
3505 return -ERESTARTNOHAND;
3506}
3507
3508#endif
3509
3510static int sigsuspend(sigset_t *set)
3511{
3512 current->saved_sigmask = current->blocked;
3513 set_current_blocked(set);
3514
3515 while (!signal_pending(current)) {
3516 __set_current_state(TASK_INTERRUPTIBLE);
3517 schedule();
3518 }
3519 set_restore_sigmask();
3520 return -ERESTARTNOHAND;
3521}
3522
3523/**
3524 * sys_rt_sigsuspend - replace the signal mask for a value with the
3525 * @unewset value until a signal is received
3526 * @unewset: new signal mask value
3527 * @sigsetsize: size of sigset_t type
3528 */
3529SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3530{
3531 sigset_t newset;
3532
3533 /* XXX: Don't preclude handling different sized sigset_t's. */
3534 if (sigsetsize != sizeof(sigset_t))
3535 return -EINVAL;
3536
3537 if (copy_from_user(&newset, unewset, sizeof(newset)))
3538 return -EFAULT;
3539 return sigsuspend(&newset);
3540}
3541
3542#ifdef CONFIG_COMPAT
3543COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3544{
3545#ifdef __BIG_ENDIAN
3546 sigset_t newset;
3547 compat_sigset_t newset32;
3548
3549 /* XXX: Don't preclude handling different sized sigset_t's. */
3550 if (sigsetsize != sizeof(sigset_t))
3551 return -EINVAL;
3552
3553 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3554 return -EFAULT;
3555 sigset_from_compat(&newset, &newset32);
3556 return sigsuspend(&newset);
3557#else
3558 /* on little-endian bitmaps don't care about granularity */
3559 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3560#endif
3561}
3562#endif
3563
3564#ifdef CONFIG_OLD_SIGSUSPEND
3565SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3566{
3567 sigset_t blocked;
3568 siginitset(&blocked, mask);
3569 return sigsuspend(&blocked);
3570}
3571#endif
3572#ifdef CONFIG_OLD_SIGSUSPEND3
3573SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3574{
3575 sigset_t blocked;
3576 siginitset(&blocked, mask);
3577 return sigsuspend(&blocked);
3578}
3579#endif
3580
3581__weak const char *arch_vma_name(struct vm_area_struct *vma)
3582{
3583 return NULL;
3584}
3585
3586void __init signals_init(void)
3587{
3588 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3589 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3590 != offsetof(struct siginfo, _sifields._pad));
3591
3592 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3593}
3594
3595#ifdef CONFIG_KGDB_KDB
3596#include <linux/kdb.h>
3597/*
3598 * kdb_send_sig_info - Allows kdb to send signals without exposing
3599 * signal internals. This function checks if the required locks are
3600 * available before calling the main signal code, to avoid kdb
3601 * deadlocks.
3602 */
3603void
3604kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3605{
3606 static struct task_struct *kdb_prev_t;
3607 int sig, new_t;
3608 if (!spin_trylock(&t->sighand->siglock)) {
3609 kdb_printf("Can't do kill command now.\n"
3610 "The sigmask lock is held somewhere else in "
3611 "kernel, try again later\n");
3612 return;
3613 }
3614 spin_unlock(&t->sighand->siglock);
3615 new_t = kdb_prev_t != t;
3616 kdb_prev_t = t;
3617 if (t->state != TASK_RUNNING && new_t) {
3618 kdb_printf("Process is not RUNNING, sending a signal from "
3619 "kdb risks deadlock\n"
3620 "on the run queue locks. "
3621 "The signal has _not_ been sent.\n"
3622 "Reissue the kill command if you want to risk "
3623 "the deadlock.\n");
3624 return;
3625 }
3626 sig = info->si_signo;
3627 if (send_sig_info(sig, info, t))
3628 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3629 sig, t->pid);
3630 else
3631 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3632}
3633#endif /* CONFIG_KGDB_KDB */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 *
9 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
10 * Changes to use preallocated sigqueue structures
11 * to allow signals to be sent reliably.
12 */
13
14#include <linux/slab.h>
15#include <linux/export.h>
16#include <linux/init.h>
17#include <linux/sched/mm.h>
18#include <linux/sched/user.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/sched/cputime.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/proc_fs.h>
26#include <linux/tty.h>
27#include <linux/binfmts.h>
28#include <linux/coredump.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/ptrace.h>
32#include <linux/signal.h>
33#include <linux/signalfd.h>
34#include <linux/ratelimit.h>
35#include <linux/tracehook.h>
36#include <linux/capability.h>
37#include <linux/freezer.h>
38#include <linux/pid_namespace.h>
39#include <linux/nsproxy.h>
40#include <linux/user_namespace.h>
41#include <linux/uprobes.h>
42#include <linux/compat.h>
43#include <linux/cn_proc.h>
44#include <linux/compiler.h>
45#include <linux/posix-timers.h>
46#include <linux/livepatch.h>
47#include <linux/cgroup.h>
48#include <linux/audit.h>
49
50#define CREATE_TRACE_POINTS
51#include <trace/events/signal.h>
52
53#include <asm/param.h>
54#include <linux/uaccess.h>
55#include <asm/unistd.h>
56#include <asm/siginfo.h>
57#include <asm/cacheflush.h>
58
59/*
60 * SLAB caches for signal bits.
61 */
62
63static struct kmem_cache *sigqueue_cachep;
64
65int print_fatal_signals __read_mostly;
66
67static void __user *sig_handler(struct task_struct *t, int sig)
68{
69 return t->sighand->action[sig - 1].sa.sa_handler;
70}
71
72static inline bool sig_handler_ignored(void __user *handler, int sig)
73{
74 /* Is it explicitly or implicitly ignored? */
75 return handler == SIG_IGN ||
76 (handler == SIG_DFL && sig_kernel_ignore(sig));
77}
78
79static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
80{
81 void __user *handler;
82
83 handler = sig_handler(t, sig);
84
85 /* SIGKILL and SIGSTOP may not be sent to the global init */
86 if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
87 return true;
88
89 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
90 handler == SIG_DFL && !(force && sig_kernel_only(sig)))
91 return true;
92
93 /* Only allow kernel generated signals to this kthread */
94 if (unlikely((t->flags & PF_KTHREAD) &&
95 (handler == SIG_KTHREAD_KERNEL) && !force))
96 return true;
97
98 return sig_handler_ignored(handler, sig);
99}
100
101static bool sig_ignored(struct task_struct *t, int sig, bool force)
102{
103 /*
104 * Blocked signals are never ignored, since the
105 * signal handler may change by the time it is
106 * unblocked.
107 */
108 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
109 return false;
110
111 /*
112 * Tracers may want to know about even ignored signal unless it
113 * is SIGKILL which can't be reported anyway but can be ignored
114 * by SIGNAL_UNKILLABLE task.
115 */
116 if (t->ptrace && sig != SIGKILL)
117 return false;
118
119 return sig_task_ignored(t, sig, force);
120}
121
122/*
123 * Re-calculate pending state from the set of locally pending
124 * signals, globally pending signals, and blocked signals.
125 */
126static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
127{
128 unsigned long ready;
129 long i;
130
131 switch (_NSIG_WORDS) {
132 default:
133 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
134 ready |= signal->sig[i] &~ blocked->sig[i];
135 break;
136
137 case 4: ready = signal->sig[3] &~ blocked->sig[3];
138 ready |= signal->sig[2] &~ blocked->sig[2];
139 ready |= signal->sig[1] &~ blocked->sig[1];
140 ready |= signal->sig[0] &~ blocked->sig[0];
141 break;
142
143 case 2: ready = signal->sig[1] &~ blocked->sig[1];
144 ready |= signal->sig[0] &~ blocked->sig[0];
145 break;
146
147 case 1: ready = signal->sig[0] &~ blocked->sig[0];
148 }
149 return ready != 0;
150}
151
152#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
153
154static bool recalc_sigpending_tsk(struct task_struct *t)
155{
156 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
157 PENDING(&t->pending, &t->blocked) ||
158 PENDING(&t->signal->shared_pending, &t->blocked) ||
159 cgroup_task_frozen(t)) {
160 set_tsk_thread_flag(t, TIF_SIGPENDING);
161 return true;
162 }
163
164 /*
165 * We must never clear the flag in another thread, or in current
166 * when it's possible the current syscall is returning -ERESTART*.
167 * So we don't clear it here, and only callers who know they should do.
168 */
169 return false;
170}
171
172/*
173 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
174 * This is superfluous when called on current, the wakeup is a harmless no-op.
175 */
176void recalc_sigpending_and_wake(struct task_struct *t)
177{
178 if (recalc_sigpending_tsk(t))
179 signal_wake_up(t, 0);
180}
181
182void recalc_sigpending(void)
183{
184 if (!recalc_sigpending_tsk(current) && !freezing(current) &&
185 !klp_patch_pending(current))
186 clear_thread_flag(TIF_SIGPENDING);
187
188}
189EXPORT_SYMBOL(recalc_sigpending);
190
191void calculate_sigpending(void)
192{
193 /* Have any signals or users of TIF_SIGPENDING been delayed
194 * until after fork?
195 */
196 spin_lock_irq(¤t->sighand->siglock);
197 set_tsk_thread_flag(current, TIF_SIGPENDING);
198 recalc_sigpending();
199 spin_unlock_irq(¤t->sighand->siglock);
200}
201
202/* Given the mask, find the first available signal that should be serviced. */
203
204#define SYNCHRONOUS_MASK \
205 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
206 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
207
208int next_signal(struct sigpending *pending, sigset_t *mask)
209{
210 unsigned long i, *s, *m, x;
211 int sig = 0;
212
213 s = pending->signal.sig;
214 m = mask->sig;
215
216 /*
217 * Handle the first word specially: it contains the
218 * synchronous signals that need to be dequeued first.
219 */
220 x = *s &~ *m;
221 if (x) {
222 if (x & SYNCHRONOUS_MASK)
223 x &= SYNCHRONOUS_MASK;
224 sig = ffz(~x) + 1;
225 return sig;
226 }
227
228 switch (_NSIG_WORDS) {
229 default:
230 for (i = 1; i < _NSIG_WORDS; ++i) {
231 x = *++s &~ *++m;
232 if (!x)
233 continue;
234 sig = ffz(~x) + i*_NSIG_BPW + 1;
235 break;
236 }
237 break;
238
239 case 2:
240 x = s[1] &~ m[1];
241 if (!x)
242 break;
243 sig = ffz(~x) + _NSIG_BPW + 1;
244 break;
245
246 case 1:
247 /* Nothing to do */
248 break;
249 }
250
251 return sig;
252}
253
254static inline void print_dropped_signal(int sig)
255{
256 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
257
258 if (!print_fatal_signals)
259 return;
260
261 if (!__ratelimit(&ratelimit_state))
262 return;
263
264 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
265 current->comm, current->pid, sig);
266}
267
268/**
269 * task_set_jobctl_pending - set jobctl pending bits
270 * @task: target task
271 * @mask: pending bits to set
272 *
273 * Clear @mask from @task->jobctl. @mask must be subset of
274 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
275 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
276 * cleared. If @task is already being killed or exiting, this function
277 * becomes noop.
278 *
279 * CONTEXT:
280 * Must be called with @task->sighand->siglock held.
281 *
282 * RETURNS:
283 * %true if @mask is set, %false if made noop because @task was dying.
284 */
285bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
286{
287 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
288 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
289 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
290
291 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
292 return false;
293
294 if (mask & JOBCTL_STOP_SIGMASK)
295 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
296
297 task->jobctl |= mask;
298 return true;
299}
300
301/**
302 * task_clear_jobctl_trapping - clear jobctl trapping bit
303 * @task: target task
304 *
305 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
306 * Clear it and wake up the ptracer. Note that we don't need any further
307 * locking. @task->siglock guarantees that @task->parent points to the
308 * ptracer.
309 *
310 * CONTEXT:
311 * Must be called with @task->sighand->siglock held.
312 */
313void task_clear_jobctl_trapping(struct task_struct *task)
314{
315 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
316 task->jobctl &= ~JOBCTL_TRAPPING;
317 smp_mb(); /* advised by wake_up_bit() */
318 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
319 }
320}
321
322/**
323 * task_clear_jobctl_pending - clear jobctl pending bits
324 * @task: target task
325 * @mask: pending bits to clear
326 *
327 * Clear @mask from @task->jobctl. @mask must be subset of
328 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
329 * STOP bits are cleared together.
330 *
331 * If clearing of @mask leaves no stop or trap pending, this function calls
332 * task_clear_jobctl_trapping().
333 *
334 * CONTEXT:
335 * Must be called with @task->sighand->siglock held.
336 */
337void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
338{
339 BUG_ON(mask & ~JOBCTL_PENDING_MASK);
340
341 if (mask & JOBCTL_STOP_PENDING)
342 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
343
344 task->jobctl &= ~mask;
345
346 if (!(task->jobctl & JOBCTL_PENDING_MASK))
347 task_clear_jobctl_trapping(task);
348}
349
350/**
351 * task_participate_group_stop - participate in a group stop
352 * @task: task participating in a group stop
353 *
354 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
355 * Group stop states are cleared and the group stop count is consumed if
356 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
357 * stop, the appropriate `SIGNAL_*` flags are set.
358 *
359 * CONTEXT:
360 * Must be called with @task->sighand->siglock held.
361 *
362 * RETURNS:
363 * %true if group stop completion should be notified to the parent, %false
364 * otherwise.
365 */
366static bool task_participate_group_stop(struct task_struct *task)
367{
368 struct signal_struct *sig = task->signal;
369 bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
370
371 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
372
373 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
374
375 if (!consume)
376 return false;
377
378 if (!WARN_ON_ONCE(sig->group_stop_count == 0))
379 sig->group_stop_count--;
380
381 /*
382 * Tell the caller to notify completion iff we are entering into a
383 * fresh group stop. Read comment in do_signal_stop() for details.
384 */
385 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
386 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
387 return true;
388 }
389 return false;
390}
391
392void task_join_group_stop(struct task_struct *task)
393{
394 /* Have the new thread join an on-going signal group stop */
395 unsigned long jobctl = current->jobctl;
396 if (jobctl & JOBCTL_STOP_PENDING) {
397 struct signal_struct *sig = current->signal;
398 unsigned long signr = jobctl & JOBCTL_STOP_SIGMASK;
399 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
400 if (task_set_jobctl_pending(task, signr | gstop)) {
401 sig->group_stop_count++;
402 }
403 }
404}
405
406/*
407 * allocate a new signal queue record
408 * - this may be called without locks if and only if t == current, otherwise an
409 * appropriate lock must be held to stop the target task from exiting
410 */
411static struct sigqueue *
412__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
413{
414 struct sigqueue *q = NULL;
415 struct user_struct *user;
416 int sigpending;
417
418 /*
419 * Protect access to @t credentials. This can go away when all
420 * callers hold rcu read lock.
421 *
422 * NOTE! A pending signal will hold on to the user refcount,
423 * and we get/put the refcount only when the sigpending count
424 * changes from/to zero.
425 */
426 rcu_read_lock();
427 user = __task_cred(t)->user;
428 sigpending = atomic_inc_return(&user->sigpending);
429 if (sigpending == 1)
430 get_uid(user);
431 rcu_read_unlock();
432
433 if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
434 q = kmem_cache_alloc(sigqueue_cachep, flags);
435 } else {
436 print_dropped_signal(sig);
437 }
438
439 if (unlikely(q == NULL)) {
440 if (atomic_dec_and_test(&user->sigpending))
441 free_uid(user);
442 } else {
443 INIT_LIST_HEAD(&q->list);
444 q->flags = 0;
445 q->user = user;
446 }
447
448 return q;
449}
450
451static void __sigqueue_free(struct sigqueue *q)
452{
453 if (q->flags & SIGQUEUE_PREALLOC)
454 return;
455 if (atomic_dec_and_test(&q->user->sigpending))
456 free_uid(q->user);
457 kmem_cache_free(sigqueue_cachep, q);
458}
459
460void flush_sigqueue(struct sigpending *queue)
461{
462 struct sigqueue *q;
463
464 sigemptyset(&queue->signal);
465 while (!list_empty(&queue->list)) {
466 q = list_entry(queue->list.next, struct sigqueue , list);
467 list_del_init(&q->list);
468 __sigqueue_free(q);
469 }
470}
471
472/*
473 * Flush all pending signals for this kthread.
474 */
475void flush_signals(struct task_struct *t)
476{
477 unsigned long flags;
478
479 spin_lock_irqsave(&t->sighand->siglock, flags);
480 clear_tsk_thread_flag(t, TIF_SIGPENDING);
481 flush_sigqueue(&t->pending);
482 flush_sigqueue(&t->signal->shared_pending);
483 spin_unlock_irqrestore(&t->sighand->siglock, flags);
484}
485EXPORT_SYMBOL(flush_signals);
486
487#ifdef CONFIG_POSIX_TIMERS
488static void __flush_itimer_signals(struct sigpending *pending)
489{
490 sigset_t signal, retain;
491 struct sigqueue *q, *n;
492
493 signal = pending->signal;
494 sigemptyset(&retain);
495
496 list_for_each_entry_safe(q, n, &pending->list, list) {
497 int sig = q->info.si_signo;
498
499 if (likely(q->info.si_code != SI_TIMER)) {
500 sigaddset(&retain, sig);
501 } else {
502 sigdelset(&signal, sig);
503 list_del_init(&q->list);
504 __sigqueue_free(q);
505 }
506 }
507
508 sigorsets(&pending->signal, &signal, &retain);
509}
510
511void flush_itimer_signals(void)
512{
513 struct task_struct *tsk = current;
514 unsigned long flags;
515
516 spin_lock_irqsave(&tsk->sighand->siglock, flags);
517 __flush_itimer_signals(&tsk->pending);
518 __flush_itimer_signals(&tsk->signal->shared_pending);
519 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
520}
521#endif
522
523void ignore_signals(struct task_struct *t)
524{
525 int i;
526
527 for (i = 0; i < _NSIG; ++i)
528 t->sighand->action[i].sa.sa_handler = SIG_IGN;
529
530 flush_signals(t);
531}
532
533/*
534 * Flush all handlers for a task.
535 */
536
537void
538flush_signal_handlers(struct task_struct *t, int force_default)
539{
540 int i;
541 struct k_sigaction *ka = &t->sighand->action[0];
542 for (i = _NSIG ; i != 0 ; i--) {
543 if (force_default || ka->sa.sa_handler != SIG_IGN)
544 ka->sa.sa_handler = SIG_DFL;
545 ka->sa.sa_flags = 0;
546#ifdef __ARCH_HAS_SA_RESTORER
547 ka->sa.sa_restorer = NULL;
548#endif
549 sigemptyset(&ka->sa.sa_mask);
550 ka++;
551 }
552}
553
554bool unhandled_signal(struct task_struct *tsk, int sig)
555{
556 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
557 if (is_global_init(tsk))
558 return true;
559
560 if (handler != SIG_IGN && handler != SIG_DFL)
561 return false;
562
563 /* if ptraced, let the tracer determine */
564 return !tsk->ptrace;
565}
566
567static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
568 bool *resched_timer)
569{
570 struct sigqueue *q, *first = NULL;
571
572 /*
573 * Collect the siginfo appropriate to this signal. Check if
574 * there is another siginfo for the same signal.
575 */
576 list_for_each_entry(q, &list->list, list) {
577 if (q->info.si_signo == sig) {
578 if (first)
579 goto still_pending;
580 first = q;
581 }
582 }
583
584 sigdelset(&list->signal, sig);
585
586 if (first) {
587still_pending:
588 list_del_init(&first->list);
589 copy_siginfo(info, &first->info);
590
591 *resched_timer =
592 (first->flags & SIGQUEUE_PREALLOC) &&
593 (info->si_code == SI_TIMER) &&
594 (info->si_sys_private);
595
596 __sigqueue_free(first);
597 } else {
598 /*
599 * Ok, it wasn't in the queue. This must be
600 * a fast-pathed signal or we must have been
601 * out of queue space. So zero out the info.
602 */
603 clear_siginfo(info);
604 info->si_signo = sig;
605 info->si_errno = 0;
606 info->si_code = SI_USER;
607 info->si_pid = 0;
608 info->si_uid = 0;
609 }
610}
611
612static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
613 kernel_siginfo_t *info, bool *resched_timer)
614{
615 int sig = next_signal(pending, mask);
616
617 if (sig)
618 collect_signal(sig, pending, info, resched_timer);
619 return sig;
620}
621
622/*
623 * Dequeue a signal and return the element to the caller, which is
624 * expected to free it.
625 *
626 * All callers have to hold the siglock.
627 */
628int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
629{
630 bool resched_timer = false;
631 int signr;
632
633 /* We only dequeue private signals from ourselves, we don't let
634 * signalfd steal them
635 */
636 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
637 if (!signr) {
638 signr = __dequeue_signal(&tsk->signal->shared_pending,
639 mask, info, &resched_timer);
640#ifdef CONFIG_POSIX_TIMERS
641 /*
642 * itimer signal ?
643 *
644 * itimers are process shared and we restart periodic
645 * itimers in the signal delivery path to prevent DoS
646 * attacks in the high resolution timer case. This is
647 * compliant with the old way of self-restarting
648 * itimers, as the SIGALRM is a legacy signal and only
649 * queued once. Changing the restart behaviour to
650 * restart the timer in the signal dequeue path is
651 * reducing the timer noise on heavy loaded !highres
652 * systems too.
653 */
654 if (unlikely(signr == SIGALRM)) {
655 struct hrtimer *tmr = &tsk->signal->real_timer;
656
657 if (!hrtimer_is_queued(tmr) &&
658 tsk->signal->it_real_incr != 0) {
659 hrtimer_forward(tmr, tmr->base->get_time(),
660 tsk->signal->it_real_incr);
661 hrtimer_restart(tmr);
662 }
663 }
664#endif
665 }
666
667 recalc_sigpending();
668 if (!signr)
669 return 0;
670
671 if (unlikely(sig_kernel_stop(signr))) {
672 /*
673 * Set a marker that we have dequeued a stop signal. Our
674 * caller might release the siglock and then the pending
675 * stop signal it is about to process is no longer in the
676 * pending bitmasks, but must still be cleared by a SIGCONT
677 * (and overruled by a SIGKILL). So those cases clear this
678 * shared flag after we've set it. Note that this flag may
679 * remain set after the signal we return is ignored or
680 * handled. That doesn't matter because its only purpose
681 * is to alert stop-signal processing code when another
682 * processor has come along and cleared the flag.
683 */
684 current->jobctl |= JOBCTL_STOP_DEQUEUED;
685 }
686#ifdef CONFIG_POSIX_TIMERS
687 if (resched_timer) {
688 /*
689 * Release the siglock to ensure proper locking order
690 * of timer locks outside of siglocks. Note, we leave
691 * irqs disabled here, since the posix-timers code is
692 * about to disable them again anyway.
693 */
694 spin_unlock(&tsk->sighand->siglock);
695 posixtimer_rearm(info);
696 spin_lock(&tsk->sighand->siglock);
697
698 /* Don't expose the si_sys_private value to userspace */
699 info->si_sys_private = 0;
700 }
701#endif
702 return signr;
703}
704EXPORT_SYMBOL_GPL(dequeue_signal);
705
706static int dequeue_synchronous_signal(kernel_siginfo_t *info)
707{
708 struct task_struct *tsk = current;
709 struct sigpending *pending = &tsk->pending;
710 struct sigqueue *q, *sync = NULL;
711
712 /*
713 * Might a synchronous signal be in the queue?
714 */
715 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
716 return 0;
717
718 /*
719 * Return the first synchronous signal in the queue.
720 */
721 list_for_each_entry(q, &pending->list, list) {
722 /* Synchronous signals have a positive si_code */
723 if ((q->info.si_code > SI_USER) &&
724 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
725 sync = q;
726 goto next;
727 }
728 }
729 return 0;
730next:
731 /*
732 * Check if there is another siginfo for the same signal.
733 */
734 list_for_each_entry_continue(q, &pending->list, list) {
735 if (q->info.si_signo == sync->info.si_signo)
736 goto still_pending;
737 }
738
739 sigdelset(&pending->signal, sync->info.si_signo);
740 recalc_sigpending();
741still_pending:
742 list_del_init(&sync->list);
743 copy_siginfo(info, &sync->info);
744 __sigqueue_free(sync);
745 return info->si_signo;
746}
747
748/*
749 * Tell a process that it has a new active signal..
750 *
751 * NOTE! we rely on the previous spin_lock to
752 * lock interrupts for us! We can only be called with
753 * "siglock" held, and the local interrupt must
754 * have been disabled when that got acquired!
755 *
756 * No need to set need_resched since signal event passing
757 * goes through ->blocked
758 */
759void signal_wake_up_state(struct task_struct *t, unsigned int state)
760{
761 set_tsk_thread_flag(t, TIF_SIGPENDING);
762 /*
763 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
764 * case. We don't check t->state here because there is a race with it
765 * executing another processor and just now entering stopped state.
766 * By using wake_up_state, we ensure the process will wake up and
767 * handle its death signal.
768 */
769 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
770 kick_process(t);
771}
772
773/*
774 * Remove signals in mask from the pending set and queue.
775 * Returns 1 if any signals were found.
776 *
777 * All callers must be holding the siglock.
778 */
779static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
780{
781 struct sigqueue *q, *n;
782 sigset_t m;
783
784 sigandsets(&m, mask, &s->signal);
785 if (sigisemptyset(&m))
786 return;
787
788 sigandnsets(&s->signal, &s->signal, mask);
789 list_for_each_entry_safe(q, n, &s->list, list) {
790 if (sigismember(mask, q->info.si_signo)) {
791 list_del_init(&q->list);
792 __sigqueue_free(q);
793 }
794 }
795}
796
797static inline int is_si_special(const struct kernel_siginfo *info)
798{
799 return info <= SEND_SIG_PRIV;
800}
801
802static inline bool si_fromuser(const struct kernel_siginfo *info)
803{
804 return info == SEND_SIG_NOINFO ||
805 (!is_si_special(info) && SI_FROMUSER(info));
806}
807
808/*
809 * called with RCU read lock from check_kill_permission()
810 */
811static bool kill_ok_by_cred(struct task_struct *t)
812{
813 const struct cred *cred = current_cred();
814 const struct cred *tcred = __task_cred(t);
815
816 return uid_eq(cred->euid, tcred->suid) ||
817 uid_eq(cred->euid, tcred->uid) ||
818 uid_eq(cred->uid, tcred->suid) ||
819 uid_eq(cred->uid, tcred->uid) ||
820 ns_capable(tcred->user_ns, CAP_KILL);
821}
822
823/*
824 * Bad permissions for sending the signal
825 * - the caller must hold the RCU read lock
826 */
827static int check_kill_permission(int sig, struct kernel_siginfo *info,
828 struct task_struct *t)
829{
830 struct pid *sid;
831 int error;
832
833 if (!valid_signal(sig))
834 return -EINVAL;
835
836 if (!si_fromuser(info))
837 return 0;
838
839 error = audit_signal_info(sig, t); /* Let audit system see the signal */
840 if (error)
841 return error;
842
843 if (!same_thread_group(current, t) &&
844 !kill_ok_by_cred(t)) {
845 switch (sig) {
846 case SIGCONT:
847 sid = task_session(t);
848 /*
849 * We don't return the error if sid == NULL. The
850 * task was unhashed, the caller must notice this.
851 */
852 if (!sid || sid == task_session(current))
853 break;
854 fallthrough;
855 default:
856 return -EPERM;
857 }
858 }
859
860 return security_task_kill(t, info, sig, NULL);
861}
862
863/**
864 * ptrace_trap_notify - schedule trap to notify ptracer
865 * @t: tracee wanting to notify tracer
866 *
867 * This function schedules sticky ptrace trap which is cleared on the next
868 * TRAP_STOP to notify ptracer of an event. @t must have been seized by
869 * ptracer.
870 *
871 * If @t is running, STOP trap will be taken. If trapped for STOP and
872 * ptracer is listening for events, tracee is woken up so that it can
873 * re-trap for the new event. If trapped otherwise, STOP trap will be
874 * eventually taken without returning to userland after the existing traps
875 * are finished by PTRACE_CONT.
876 *
877 * CONTEXT:
878 * Must be called with @task->sighand->siglock held.
879 */
880static void ptrace_trap_notify(struct task_struct *t)
881{
882 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
883 assert_spin_locked(&t->sighand->siglock);
884
885 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
886 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
887}
888
889/*
890 * Handle magic process-wide effects of stop/continue signals. Unlike
891 * the signal actions, these happen immediately at signal-generation
892 * time regardless of blocking, ignoring, or handling. This does the
893 * actual continuing for SIGCONT, but not the actual stopping for stop
894 * signals. The process stop is done as a signal action for SIG_DFL.
895 *
896 * Returns true if the signal should be actually delivered, otherwise
897 * it should be dropped.
898 */
899static bool prepare_signal(int sig, struct task_struct *p, bool force)
900{
901 struct signal_struct *signal = p->signal;
902 struct task_struct *t;
903 sigset_t flush;
904
905 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
906 if (!(signal->flags & SIGNAL_GROUP_EXIT))
907 return sig == SIGKILL;
908 /*
909 * The process is in the middle of dying, nothing to do.
910 */
911 } else if (sig_kernel_stop(sig)) {
912 /*
913 * This is a stop signal. Remove SIGCONT from all queues.
914 */
915 siginitset(&flush, sigmask(SIGCONT));
916 flush_sigqueue_mask(&flush, &signal->shared_pending);
917 for_each_thread(p, t)
918 flush_sigqueue_mask(&flush, &t->pending);
919 } else if (sig == SIGCONT) {
920 unsigned int why;
921 /*
922 * Remove all stop signals from all queues, wake all threads.
923 */
924 siginitset(&flush, SIG_KERNEL_STOP_MASK);
925 flush_sigqueue_mask(&flush, &signal->shared_pending);
926 for_each_thread(p, t) {
927 flush_sigqueue_mask(&flush, &t->pending);
928 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
929 if (likely(!(t->ptrace & PT_SEIZED)))
930 wake_up_state(t, __TASK_STOPPED);
931 else
932 ptrace_trap_notify(t);
933 }
934
935 /*
936 * Notify the parent with CLD_CONTINUED if we were stopped.
937 *
938 * If we were in the middle of a group stop, we pretend it
939 * was already finished, and then continued. Since SIGCHLD
940 * doesn't queue we report only CLD_STOPPED, as if the next
941 * CLD_CONTINUED was dropped.
942 */
943 why = 0;
944 if (signal->flags & SIGNAL_STOP_STOPPED)
945 why |= SIGNAL_CLD_CONTINUED;
946 else if (signal->group_stop_count)
947 why |= SIGNAL_CLD_STOPPED;
948
949 if (why) {
950 /*
951 * The first thread which returns from do_signal_stop()
952 * will take ->siglock, notice SIGNAL_CLD_MASK, and
953 * notify its parent. See get_signal().
954 */
955 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
956 signal->group_stop_count = 0;
957 signal->group_exit_code = 0;
958 }
959 }
960
961 return !sig_ignored(p, sig, force);
962}
963
964/*
965 * Test if P wants to take SIG. After we've checked all threads with this,
966 * it's equivalent to finding no threads not blocking SIG. Any threads not
967 * blocking SIG were ruled out because they are not running and already
968 * have pending signals. Such threads will dequeue from the shared queue
969 * as soon as they're available, so putting the signal on the shared queue
970 * will be equivalent to sending it to one such thread.
971 */
972static inline bool wants_signal(int sig, struct task_struct *p)
973{
974 if (sigismember(&p->blocked, sig))
975 return false;
976
977 if (p->flags & PF_EXITING)
978 return false;
979
980 if (sig == SIGKILL)
981 return true;
982
983 if (task_is_stopped_or_traced(p))
984 return false;
985
986 return task_curr(p) || !signal_pending(p);
987}
988
989static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
990{
991 struct signal_struct *signal = p->signal;
992 struct task_struct *t;
993
994 /*
995 * Now find a thread we can wake up to take the signal off the queue.
996 *
997 * If the main thread wants the signal, it gets first crack.
998 * Probably the least surprising to the average bear.
999 */
1000 if (wants_signal(sig, p))
1001 t = p;
1002 else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1003 /*
1004 * There is just one thread and it does not need to be woken.
1005 * It will dequeue unblocked signals before it runs again.
1006 */
1007 return;
1008 else {
1009 /*
1010 * Otherwise try to find a suitable thread.
1011 */
1012 t = signal->curr_target;
1013 while (!wants_signal(sig, t)) {
1014 t = next_thread(t);
1015 if (t == signal->curr_target)
1016 /*
1017 * No thread needs to be woken.
1018 * Any eligible threads will see
1019 * the signal in the queue soon.
1020 */
1021 return;
1022 }
1023 signal->curr_target = t;
1024 }
1025
1026 /*
1027 * Found a killable thread. If the signal will be fatal,
1028 * then start taking the whole group down immediately.
1029 */
1030 if (sig_fatal(p, sig) &&
1031 !(signal->flags & SIGNAL_GROUP_EXIT) &&
1032 !sigismember(&t->real_blocked, sig) &&
1033 (sig == SIGKILL || !p->ptrace)) {
1034 /*
1035 * This signal will be fatal to the whole group.
1036 */
1037 if (!sig_kernel_coredump(sig)) {
1038 /*
1039 * Start a group exit and wake everybody up.
1040 * This way we don't have other threads
1041 * running and doing things after a slower
1042 * thread has the fatal signal pending.
1043 */
1044 signal->flags = SIGNAL_GROUP_EXIT;
1045 signal->group_exit_code = sig;
1046 signal->group_stop_count = 0;
1047 t = p;
1048 do {
1049 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1050 sigaddset(&t->pending.signal, SIGKILL);
1051 signal_wake_up(t, 1);
1052 } while_each_thread(p, t);
1053 return;
1054 }
1055 }
1056
1057 /*
1058 * The signal is already in the shared-pending queue.
1059 * Tell the chosen thread to wake up and dequeue it.
1060 */
1061 signal_wake_up(t, sig == SIGKILL);
1062 return;
1063}
1064
1065static inline bool legacy_queue(struct sigpending *signals, int sig)
1066{
1067 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1068}
1069
1070static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1071 enum pid_type type, bool force)
1072{
1073 struct sigpending *pending;
1074 struct sigqueue *q;
1075 int override_rlimit;
1076 int ret = 0, result;
1077
1078 assert_spin_locked(&t->sighand->siglock);
1079
1080 result = TRACE_SIGNAL_IGNORED;
1081 if (!prepare_signal(sig, t, force))
1082 goto ret;
1083
1084 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1085 /*
1086 * Short-circuit ignored signals and support queuing
1087 * exactly one non-rt signal, so that we can get more
1088 * detailed information about the cause of the signal.
1089 */
1090 result = TRACE_SIGNAL_ALREADY_PENDING;
1091 if (legacy_queue(pending, sig))
1092 goto ret;
1093
1094 result = TRACE_SIGNAL_DELIVERED;
1095 /*
1096 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1097 */
1098 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1099 goto out_set;
1100
1101 /*
1102 * Real-time signals must be queued if sent by sigqueue, or
1103 * some other real-time mechanism. It is implementation
1104 * defined whether kill() does so. We attempt to do so, on
1105 * the principle of least surprise, but since kill is not
1106 * allowed to fail with EAGAIN when low on memory we just
1107 * make sure at least one signal gets delivered and don't
1108 * pass on the info struct.
1109 */
1110 if (sig < SIGRTMIN)
1111 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1112 else
1113 override_rlimit = 0;
1114
1115 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1116 if (q) {
1117 list_add_tail(&q->list, &pending->list);
1118 switch ((unsigned long) info) {
1119 case (unsigned long) SEND_SIG_NOINFO:
1120 clear_siginfo(&q->info);
1121 q->info.si_signo = sig;
1122 q->info.si_errno = 0;
1123 q->info.si_code = SI_USER;
1124 q->info.si_pid = task_tgid_nr_ns(current,
1125 task_active_pid_ns(t));
1126 rcu_read_lock();
1127 q->info.si_uid =
1128 from_kuid_munged(task_cred_xxx(t, user_ns),
1129 current_uid());
1130 rcu_read_unlock();
1131 break;
1132 case (unsigned long) SEND_SIG_PRIV:
1133 clear_siginfo(&q->info);
1134 q->info.si_signo = sig;
1135 q->info.si_errno = 0;
1136 q->info.si_code = SI_KERNEL;
1137 q->info.si_pid = 0;
1138 q->info.si_uid = 0;
1139 break;
1140 default:
1141 copy_siginfo(&q->info, info);
1142 break;
1143 }
1144 } else if (!is_si_special(info) &&
1145 sig >= SIGRTMIN && info->si_code != SI_USER) {
1146 /*
1147 * Queue overflow, abort. We may abort if the
1148 * signal was rt and sent by user using something
1149 * other than kill().
1150 */
1151 result = TRACE_SIGNAL_OVERFLOW_FAIL;
1152 ret = -EAGAIN;
1153 goto ret;
1154 } else {
1155 /*
1156 * This is a silent loss of information. We still
1157 * send the signal, but the *info bits are lost.
1158 */
1159 result = TRACE_SIGNAL_LOSE_INFO;
1160 }
1161
1162out_set:
1163 signalfd_notify(t, sig);
1164 sigaddset(&pending->signal, sig);
1165
1166 /* Let multiprocess signals appear after on-going forks */
1167 if (type > PIDTYPE_TGID) {
1168 struct multiprocess_signals *delayed;
1169 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1170 sigset_t *signal = &delayed->signal;
1171 /* Can't queue both a stop and a continue signal */
1172 if (sig == SIGCONT)
1173 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1174 else if (sig_kernel_stop(sig))
1175 sigdelset(signal, SIGCONT);
1176 sigaddset(signal, sig);
1177 }
1178 }
1179
1180 complete_signal(sig, t, type);
1181ret:
1182 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1183 return ret;
1184}
1185
1186static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1187{
1188 bool ret = false;
1189 switch (siginfo_layout(info->si_signo, info->si_code)) {
1190 case SIL_KILL:
1191 case SIL_CHLD:
1192 case SIL_RT:
1193 ret = true;
1194 break;
1195 case SIL_TIMER:
1196 case SIL_POLL:
1197 case SIL_FAULT:
1198 case SIL_FAULT_MCEERR:
1199 case SIL_FAULT_BNDERR:
1200 case SIL_FAULT_PKUERR:
1201 case SIL_SYS:
1202 ret = false;
1203 break;
1204 }
1205 return ret;
1206}
1207
1208static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1209 enum pid_type type)
1210{
1211 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1212 bool force = false;
1213
1214 if (info == SEND_SIG_NOINFO) {
1215 /* Force if sent from an ancestor pid namespace */
1216 force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1217 } else if (info == SEND_SIG_PRIV) {
1218 /* Don't ignore kernel generated signals */
1219 force = true;
1220 } else if (has_si_pid_and_uid(info)) {
1221 /* SIGKILL and SIGSTOP is special or has ids */
1222 struct user_namespace *t_user_ns;
1223
1224 rcu_read_lock();
1225 t_user_ns = task_cred_xxx(t, user_ns);
1226 if (current_user_ns() != t_user_ns) {
1227 kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1228 info->si_uid = from_kuid_munged(t_user_ns, uid);
1229 }
1230 rcu_read_unlock();
1231
1232 /* A kernel generated signal? */
1233 force = (info->si_code == SI_KERNEL);
1234
1235 /* From an ancestor pid namespace? */
1236 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1237 info->si_pid = 0;
1238 force = true;
1239 }
1240 }
1241 return __send_signal(sig, info, t, type, force);
1242}
1243
1244static void print_fatal_signal(int signr)
1245{
1246 struct pt_regs *regs = signal_pt_regs();
1247 pr_info("potentially unexpected fatal signal %d.\n", signr);
1248
1249#if defined(__i386__) && !defined(__arch_um__)
1250 pr_info("code at %08lx: ", regs->ip);
1251 {
1252 int i;
1253 for (i = 0; i < 16; i++) {
1254 unsigned char insn;
1255
1256 if (get_user(insn, (unsigned char *)(regs->ip + i)))
1257 break;
1258 pr_cont("%02x ", insn);
1259 }
1260 }
1261 pr_cont("\n");
1262#endif
1263 preempt_disable();
1264 show_regs(regs);
1265 preempt_enable();
1266}
1267
1268static int __init setup_print_fatal_signals(char *str)
1269{
1270 get_option (&str, &print_fatal_signals);
1271
1272 return 1;
1273}
1274
1275__setup("print-fatal-signals=", setup_print_fatal_signals);
1276
1277int
1278__group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1279{
1280 return send_signal(sig, info, p, PIDTYPE_TGID);
1281}
1282
1283int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1284 enum pid_type type)
1285{
1286 unsigned long flags;
1287 int ret = -ESRCH;
1288
1289 if (lock_task_sighand(p, &flags)) {
1290 ret = send_signal(sig, info, p, type);
1291 unlock_task_sighand(p, &flags);
1292 }
1293
1294 return ret;
1295}
1296
1297/*
1298 * Force a signal that the process can't ignore: if necessary
1299 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1300 *
1301 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1302 * since we do not want to have a signal handler that was blocked
1303 * be invoked when user space had explicitly blocked it.
1304 *
1305 * We don't want to have recursive SIGSEGV's etc, for example,
1306 * that is why we also clear SIGNAL_UNKILLABLE.
1307 */
1308static int
1309force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
1310{
1311 unsigned long int flags;
1312 int ret, blocked, ignored;
1313 struct k_sigaction *action;
1314 int sig = info->si_signo;
1315
1316 spin_lock_irqsave(&t->sighand->siglock, flags);
1317 action = &t->sighand->action[sig-1];
1318 ignored = action->sa.sa_handler == SIG_IGN;
1319 blocked = sigismember(&t->blocked, sig);
1320 if (blocked || ignored) {
1321 action->sa.sa_handler = SIG_DFL;
1322 if (blocked) {
1323 sigdelset(&t->blocked, sig);
1324 recalc_sigpending_and_wake(t);
1325 }
1326 }
1327 /*
1328 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1329 * debugging to leave init killable.
1330 */
1331 if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1332 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1333 ret = send_signal(sig, info, t, PIDTYPE_PID);
1334 spin_unlock_irqrestore(&t->sighand->siglock, flags);
1335
1336 return ret;
1337}
1338
1339int force_sig_info(struct kernel_siginfo *info)
1340{
1341 return force_sig_info_to_task(info, current);
1342}
1343
1344/*
1345 * Nuke all other threads in the group.
1346 */
1347int zap_other_threads(struct task_struct *p)
1348{
1349 struct task_struct *t = p;
1350 int count = 0;
1351
1352 p->signal->group_stop_count = 0;
1353
1354 while_each_thread(p, t) {
1355 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1356 count++;
1357
1358 /* Don't bother with already dead threads */
1359 if (t->exit_state)
1360 continue;
1361 sigaddset(&t->pending.signal, SIGKILL);
1362 signal_wake_up(t, 1);
1363 }
1364
1365 return count;
1366}
1367
1368struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1369 unsigned long *flags)
1370{
1371 struct sighand_struct *sighand;
1372
1373 rcu_read_lock();
1374 for (;;) {
1375 sighand = rcu_dereference(tsk->sighand);
1376 if (unlikely(sighand == NULL))
1377 break;
1378
1379 /*
1380 * This sighand can be already freed and even reused, but
1381 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1382 * initializes ->siglock: this slab can't go away, it has
1383 * the same object type, ->siglock can't be reinitialized.
1384 *
1385 * We need to ensure that tsk->sighand is still the same
1386 * after we take the lock, we can race with de_thread() or
1387 * __exit_signal(). In the latter case the next iteration
1388 * must see ->sighand == NULL.
1389 */
1390 spin_lock_irqsave(&sighand->siglock, *flags);
1391 if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1392 break;
1393 spin_unlock_irqrestore(&sighand->siglock, *flags);
1394 }
1395 rcu_read_unlock();
1396
1397 return sighand;
1398}
1399
1400/*
1401 * send signal info to all the members of a group
1402 */
1403int group_send_sig_info(int sig, struct kernel_siginfo *info,
1404 struct task_struct *p, enum pid_type type)
1405{
1406 int ret;
1407
1408 rcu_read_lock();
1409 ret = check_kill_permission(sig, info, p);
1410 rcu_read_unlock();
1411
1412 if (!ret && sig)
1413 ret = do_send_sig_info(sig, info, p, type);
1414
1415 return ret;
1416}
1417
1418/*
1419 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1420 * control characters do (^C, ^Z etc)
1421 * - the caller must hold at least a readlock on tasklist_lock
1422 */
1423int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1424{
1425 struct task_struct *p = NULL;
1426 int retval, success;
1427
1428 success = 0;
1429 retval = -ESRCH;
1430 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1431 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1432 success |= !err;
1433 retval = err;
1434 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1435 return success ? 0 : retval;
1436}
1437
1438int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1439{
1440 int error = -ESRCH;
1441 struct task_struct *p;
1442
1443 for (;;) {
1444 rcu_read_lock();
1445 p = pid_task(pid, PIDTYPE_PID);
1446 if (p)
1447 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1448 rcu_read_unlock();
1449 if (likely(!p || error != -ESRCH))
1450 return error;
1451
1452 /*
1453 * The task was unhashed in between, try again. If it
1454 * is dead, pid_task() will return NULL, if we race with
1455 * de_thread() it will find the new leader.
1456 */
1457 }
1458}
1459
1460static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1461{
1462 int error;
1463 rcu_read_lock();
1464 error = kill_pid_info(sig, info, find_vpid(pid));
1465 rcu_read_unlock();
1466 return error;
1467}
1468
1469static inline bool kill_as_cred_perm(const struct cred *cred,
1470 struct task_struct *target)
1471{
1472 const struct cred *pcred = __task_cred(target);
1473
1474 return uid_eq(cred->euid, pcred->suid) ||
1475 uid_eq(cred->euid, pcred->uid) ||
1476 uid_eq(cred->uid, pcred->suid) ||
1477 uid_eq(cred->uid, pcred->uid);
1478}
1479
1480/*
1481 * The usb asyncio usage of siginfo is wrong. The glibc support
1482 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1483 * AKA after the generic fields:
1484 * kernel_pid_t si_pid;
1485 * kernel_uid32_t si_uid;
1486 * sigval_t si_value;
1487 *
1488 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1489 * after the generic fields is:
1490 * void __user *si_addr;
1491 *
1492 * This is a practical problem when there is a 64bit big endian kernel
1493 * and a 32bit userspace. As the 32bit address will encoded in the low
1494 * 32bits of the pointer. Those low 32bits will be stored at higher
1495 * address than appear in a 32 bit pointer. So userspace will not
1496 * see the address it was expecting for it's completions.
1497 *
1498 * There is nothing in the encoding that can allow
1499 * copy_siginfo_to_user32 to detect this confusion of formats, so
1500 * handle this by requiring the caller of kill_pid_usb_asyncio to
1501 * notice when this situration takes place and to store the 32bit
1502 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1503 * parameter.
1504 */
1505int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1506 struct pid *pid, const struct cred *cred)
1507{
1508 struct kernel_siginfo info;
1509 struct task_struct *p;
1510 unsigned long flags;
1511 int ret = -EINVAL;
1512
1513 if (!valid_signal(sig))
1514 return ret;
1515
1516 clear_siginfo(&info);
1517 info.si_signo = sig;
1518 info.si_errno = errno;
1519 info.si_code = SI_ASYNCIO;
1520 *((sigval_t *)&info.si_pid) = addr;
1521
1522 rcu_read_lock();
1523 p = pid_task(pid, PIDTYPE_PID);
1524 if (!p) {
1525 ret = -ESRCH;
1526 goto out_unlock;
1527 }
1528 if (!kill_as_cred_perm(cred, p)) {
1529 ret = -EPERM;
1530 goto out_unlock;
1531 }
1532 ret = security_task_kill(p, &info, sig, cred);
1533 if (ret)
1534 goto out_unlock;
1535
1536 if (sig) {
1537 if (lock_task_sighand(p, &flags)) {
1538 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1539 unlock_task_sighand(p, &flags);
1540 } else
1541 ret = -ESRCH;
1542 }
1543out_unlock:
1544 rcu_read_unlock();
1545 return ret;
1546}
1547EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1548
1549/*
1550 * kill_something_info() interprets pid in interesting ways just like kill(2).
1551 *
1552 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1553 * is probably wrong. Should make it like BSD or SYSV.
1554 */
1555
1556static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1557{
1558 int ret;
1559
1560 if (pid > 0)
1561 return kill_proc_info(sig, info, pid);
1562
1563 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1564 if (pid == INT_MIN)
1565 return -ESRCH;
1566
1567 read_lock(&tasklist_lock);
1568 if (pid != -1) {
1569 ret = __kill_pgrp_info(sig, info,
1570 pid ? find_vpid(-pid) : task_pgrp(current));
1571 } else {
1572 int retval = 0, count = 0;
1573 struct task_struct * p;
1574
1575 for_each_process(p) {
1576 if (task_pid_vnr(p) > 1 &&
1577 !same_thread_group(p, current)) {
1578 int err = group_send_sig_info(sig, info, p,
1579 PIDTYPE_MAX);
1580 ++count;
1581 if (err != -EPERM)
1582 retval = err;
1583 }
1584 }
1585 ret = count ? retval : -ESRCH;
1586 }
1587 read_unlock(&tasklist_lock);
1588
1589 return ret;
1590}
1591
1592/*
1593 * These are for backward compatibility with the rest of the kernel source.
1594 */
1595
1596int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1597{
1598 /*
1599 * Make sure legacy kernel users don't send in bad values
1600 * (normal paths check this in check_kill_permission).
1601 */
1602 if (!valid_signal(sig))
1603 return -EINVAL;
1604
1605 return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1606}
1607EXPORT_SYMBOL(send_sig_info);
1608
1609#define __si_special(priv) \
1610 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1611
1612int
1613send_sig(int sig, struct task_struct *p, int priv)
1614{
1615 return send_sig_info(sig, __si_special(priv), p);
1616}
1617EXPORT_SYMBOL(send_sig);
1618
1619void force_sig(int sig)
1620{
1621 struct kernel_siginfo info;
1622
1623 clear_siginfo(&info);
1624 info.si_signo = sig;
1625 info.si_errno = 0;
1626 info.si_code = SI_KERNEL;
1627 info.si_pid = 0;
1628 info.si_uid = 0;
1629 force_sig_info(&info);
1630}
1631EXPORT_SYMBOL(force_sig);
1632
1633/*
1634 * When things go south during signal handling, we
1635 * will force a SIGSEGV. And if the signal that caused
1636 * the problem was already a SIGSEGV, we'll want to
1637 * make sure we don't even try to deliver the signal..
1638 */
1639void force_sigsegv(int sig)
1640{
1641 struct task_struct *p = current;
1642
1643 if (sig == SIGSEGV) {
1644 unsigned long flags;
1645 spin_lock_irqsave(&p->sighand->siglock, flags);
1646 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1647 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1648 }
1649 force_sig(SIGSEGV);
1650}
1651
1652int force_sig_fault_to_task(int sig, int code, void __user *addr
1653 ___ARCH_SI_TRAPNO(int trapno)
1654 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1655 , struct task_struct *t)
1656{
1657 struct kernel_siginfo info;
1658
1659 clear_siginfo(&info);
1660 info.si_signo = sig;
1661 info.si_errno = 0;
1662 info.si_code = code;
1663 info.si_addr = addr;
1664#ifdef __ARCH_SI_TRAPNO
1665 info.si_trapno = trapno;
1666#endif
1667#ifdef __ia64__
1668 info.si_imm = imm;
1669 info.si_flags = flags;
1670 info.si_isr = isr;
1671#endif
1672 return force_sig_info_to_task(&info, t);
1673}
1674
1675int force_sig_fault(int sig, int code, void __user *addr
1676 ___ARCH_SI_TRAPNO(int trapno)
1677 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1678{
1679 return force_sig_fault_to_task(sig, code, addr
1680 ___ARCH_SI_TRAPNO(trapno)
1681 ___ARCH_SI_IA64(imm, flags, isr), current);
1682}
1683
1684int send_sig_fault(int sig, int code, void __user *addr
1685 ___ARCH_SI_TRAPNO(int trapno)
1686 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1687 , struct task_struct *t)
1688{
1689 struct kernel_siginfo info;
1690
1691 clear_siginfo(&info);
1692 info.si_signo = sig;
1693 info.si_errno = 0;
1694 info.si_code = code;
1695 info.si_addr = addr;
1696#ifdef __ARCH_SI_TRAPNO
1697 info.si_trapno = trapno;
1698#endif
1699#ifdef __ia64__
1700 info.si_imm = imm;
1701 info.si_flags = flags;
1702 info.si_isr = isr;
1703#endif
1704 return send_sig_info(info.si_signo, &info, t);
1705}
1706
1707int force_sig_mceerr(int code, void __user *addr, short lsb)
1708{
1709 struct kernel_siginfo info;
1710
1711 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1712 clear_siginfo(&info);
1713 info.si_signo = SIGBUS;
1714 info.si_errno = 0;
1715 info.si_code = code;
1716 info.si_addr = addr;
1717 info.si_addr_lsb = lsb;
1718 return force_sig_info(&info);
1719}
1720
1721int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1722{
1723 struct kernel_siginfo info;
1724
1725 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1726 clear_siginfo(&info);
1727 info.si_signo = SIGBUS;
1728 info.si_errno = 0;
1729 info.si_code = code;
1730 info.si_addr = addr;
1731 info.si_addr_lsb = lsb;
1732 return send_sig_info(info.si_signo, &info, t);
1733}
1734EXPORT_SYMBOL(send_sig_mceerr);
1735
1736int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1737{
1738 struct kernel_siginfo info;
1739
1740 clear_siginfo(&info);
1741 info.si_signo = SIGSEGV;
1742 info.si_errno = 0;
1743 info.si_code = SEGV_BNDERR;
1744 info.si_addr = addr;
1745 info.si_lower = lower;
1746 info.si_upper = upper;
1747 return force_sig_info(&info);
1748}
1749
1750#ifdef SEGV_PKUERR
1751int force_sig_pkuerr(void __user *addr, u32 pkey)
1752{
1753 struct kernel_siginfo info;
1754
1755 clear_siginfo(&info);
1756 info.si_signo = SIGSEGV;
1757 info.si_errno = 0;
1758 info.si_code = SEGV_PKUERR;
1759 info.si_addr = addr;
1760 info.si_pkey = pkey;
1761 return force_sig_info(&info);
1762}
1763#endif
1764
1765/* For the crazy architectures that include trap information in
1766 * the errno field, instead of an actual errno value.
1767 */
1768int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1769{
1770 struct kernel_siginfo info;
1771
1772 clear_siginfo(&info);
1773 info.si_signo = SIGTRAP;
1774 info.si_errno = errno;
1775 info.si_code = TRAP_HWBKPT;
1776 info.si_addr = addr;
1777 return force_sig_info(&info);
1778}
1779
1780int kill_pgrp(struct pid *pid, int sig, int priv)
1781{
1782 int ret;
1783
1784 read_lock(&tasklist_lock);
1785 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1786 read_unlock(&tasklist_lock);
1787
1788 return ret;
1789}
1790EXPORT_SYMBOL(kill_pgrp);
1791
1792int kill_pid(struct pid *pid, int sig, int priv)
1793{
1794 return kill_pid_info(sig, __si_special(priv), pid);
1795}
1796EXPORT_SYMBOL(kill_pid);
1797
1798/*
1799 * These functions support sending signals using preallocated sigqueue
1800 * structures. This is needed "because realtime applications cannot
1801 * afford to lose notifications of asynchronous events, like timer
1802 * expirations or I/O completions". In the case of POSIX Timers
1803 * we allocate the sigqueue structure from the timer_create. If this
1804 * allocation fails we are able to report the failure to the application
1805 * with an EAGAIN error.
1806 */
1807struct sigqueue *sigqueue_alloc(void)
1808{
1809 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1810
1811 if (q)
1812 q->flags |= SIGQUEUE_PREALLOC;
1813
1814 return q;
1815}
1816
1817void sigqueue_free(struct sigqueue *q)
1818{
1819 unsigned long flags;
1820 spinlock_t *lock = ¤t->sighand->siglock;
1821
1822 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1823 /*
1824 * We must hold ->siglock while testing q->list
1825 * to serialize with collect_signal() or with
1826 * __exit_signal()->flush_sigqueue().
1827 */
1828 spin_lock_irqsave(lock, flags);
1829 q->flags &= ~SIGQUEUE_PREALLOC;
1830 /*
1831 * If it is queued it will be freed when dequeued,
1832 * like the "regular" sigqueue.
1833 */
1834 if (!list_empty(&q->list))
1835 q = NULL;
1836 spin_unlock_irqrestore(lock, flags);
1837
1838 if (q)
1839 __sigqueue_free(q);
1840}
1841
1842int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1843{
1844 int sig = q->info.si_signo;
1845 struct sigpending *pending;
1846 struct task_struct *t;
1847 unsigned long flags;
1848 int ret, result;
1849
1850 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1851
1852 ret = -1;
1853 rcu_read_lock();
1854 t = pid_task(pid, type);
1855 if (!t || !likely(lock_task_sighand(t, &flags)))
1856 goto ret;
1857
1858 ret = 1; /* the signal is ignored */
1859 result = TRACE_SIGNAL_IGNORED;
1860 if (!prepare_signal(sig, t, false))
1861 goto out;
1862
1863 ret = 0;
1864 if (unlikely(!list_empty(&q->list))) {
1865 /*
1866 * If an SI_TIMER entry is already queue just increment
1867 * the overrun count.
1868 */
1869 BUG_ON(q->info.si_code != SI_TIMER);
1870 q->info.si_overrun++;
1871 result = TRACE_SIGNAL_ALREADY_PENDING;
1872 goto out;
1873 }
1874 q->info.si_overrun = 0;
1875
1876 signalfd_notify(t, sig);
1877 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1878 list_add_tail(&q->list, &pending->list);
1879 sigaddset(&pending->signal, sig);
1880 complete_signal(sig, t, type);
1881 result = TRACE_SIGNAL_DELIVERED;
1882out:
1883 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1884 unlock_task_sighand(t, &flags);
1885ret:
1886 rcu_read_unlock();
1887 return ret;
1888}
1889
1890static void do_notify_pidfd(struct task_struct *task)
1891{
1892 struct pid *pid;
1893
1894 WARN_ON(task->exit_state == 0);
1895 pid = task_pid(task);
1896 wake_up_all(&pid->wait_pidfd);
1897}
1898
1899/*
1900 * Let a parent know about the death of a child.
1901 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1902 *
1903 * Returns true if our parent ignored us and so we've switched to
1904 * self-reaping.
1905 */
1906bool do_notify_parent(struct task_struct *tsk, int sig)
1907{
1908 struct kernel_siginfo info;
1909 unsigned long flags;
1910 struct sighand_struct *psig;
1911 bool autoreap = false;
1912 u64 utime, stime;
1913
1914 BUG_ON(sig == -1);
1915
1916 /* do_notify_parent_cldstop should have been called instead. */
1917 BUG_ON(task_is_stopped_or_traced(tsk));
1918
1919 BUG_ON(!tsk->ptrace &&
1920 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1921
1922 /* Wake up all pidfd waiters */
1923 do_notify_pidfd(tsk);
1924
1925 if (sig != SIGCHLD) {
1926 /*
1927 * This is only possible if parent == real_parent.
1928 * Check if it has changed security domain.
1929 */
1930 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
1931 sig = SIGCHLD;
1932 }
1933
1934 clear_siginfo(&info);
1935 info.si_signo = sig;
1936 info.si_errno = 0;
1937 /*
1938 * We are under tasklist_lock here so our parent is tied to
1939 * us and cannot change.
1940 *
1941 * task_active_pid_ns will always return the same pid namespace
1942 * until a task passes through release_task.
1943 *
1944 * write_lock() currently calls preempt_disable() which is the
1945 * same as rcu_read_lock(), but according to Oleg, this is not
1946 * correct to rely on this
1947 */
1948 rcu_read_lock();
1949 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1950 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1951 task_uid(tsk));
1952 rcu_read_unlock();
1953
1954 task_cputime(tsk, &utime, &stime);
1955 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1956 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1957
1958 info.si_status = tsk->exit_code & 0x7f;
1959 if (tsk->exit_code & 0x80)
1960 info.si_code = CLD_DUMPED;
1961 else if (tsk->exit_code & 0x7f)
1962 info.si_code = CLD_KILLED;
1963 else {
1964 info.si_code = CLD_EXITED;
1965 info.si_status = tsk->exit_code >> 8;
1966 }
1967
1968 psig = tsk->parent->sighand;
1969 spin_lock_irqsave(&psig->siglock, flags);
1970 if (!tsk->ptrace && sig == SIGCHLD &&
1971 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1972 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1973 /*
1974 * We are exiting and our parent doesn't care. POSIX.1
1975 * defines special semantics for setting SIGCHLD to SIG_IGN
1976 * or setting the SA_NOCLDWAIT flag: we should be reaped
1977 * automatically and not left for our parent's wait4 call.
1978 * Rather than having the parent do it as a magic kind of
1979 * signal handler, we just set this to tell do_exit that we
1980 * can be cleaned up without becoming a zombie. Note that
1981 * we still call __wake_up_parent in this case, because a
1982 * blocked sys_wait4 might now return -ECHILD.
1983 *
1984 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1985 * is implementation-defined: we do (if you don't want
1986 * it, just use SIG_IGN instead).
1987 */
1988 autoreap = true;
1989 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1990 sig = 0;
1991 }
1992 /*
1993 * Send with __send_signal as si_pid and si_uid are in the
1994 * parent's namespaces.
1995 */
1996 if (valid_signal(sig) && sig)
1997 __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
1998 __wake_up_parent(tsk, tsk->parent);
1999 spin_unlock_irqrestore(&psig->siglock, flags);
2000
2001 return autoreap;
2002}
2003
2004/**
2005 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2006 * @tsk: task reporting the state change
2007 * @for_ptracer: the notification is for ptracer
2008 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2009 *
2010 * Notify @tsk's parent that the stopped/continued state has changed. If
2011 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2012 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2013 *
2014 * CONTEXT:
2015 * Must be called with tasklist_lock at least read locked.
2016 */
2017static void do_notify_parent_cldstop(struct task_struct *tsk,
2018 bool for_ptracer, int why)
2019{
2020 struct kernel_siginfo info;
2021 unsigned long flags;
2022 struct task_struct *parent;
2023 struct sighand_struct *sighand;
2024 u64 utime, stime;
2025
2026 if (for_ptracer) {
2027 parent = tsk->parent;
2028 } else {
2029 tsk = tsk->group_leader;
2030 parent = tsk->real_parent;
2031 }
2032
2033 clear_siginfo(&info);
2034 info.si_signo = SIGCHLD;
2035 info.si_errno = 0;
2036 /*
2037 * see comment in do_notify_parent() about the following 4 lines
2038 */
2039 rcu_read_lock();
2040 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2041 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2042 rcu_read_unlock();
2043
2044 task_cputime(tsk, &utime, &stime);
2045 info.si_utime = nsec_to_clock_t(utime);
2046 info.si_stime = nsec_to_clock_t(stime);
2047
2048 info.si_code = why;
2049 switch (why) {
2050 case CLD_CONTINUED:
2051 info.si_status = SIGCONT;
2052 break;
2053 case CLD_STOPPED:
2054 info.si_status = tsk->signal->group_exit_code & 0x7f;
2055 break;
2056 case CLD_TRAPPED:
2057 info.si_status = tsk->exit_code & 0x7f;
2058 break;
2059 default:
2060 BUG();
2061 }
2062
2063 sighand = parent->sighand;
2064 spin_lock_irqsave(&sighand->siglock, flags);
2065 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2066 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2067 __group_send_sig_info(SIGCHLD, &info, parent);
2068 /*
2069 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2070 */
2071 __wake_up_parent(tsk, parent);
2072 spin_unlock_irqrestore(&sighand->siglock, flags);
2073}
2074
2075static inline bool may_ptrace_stop(void)
2076{
2077 if (!likely(current->ptrace))
2078 return false;
2079 /*
2080 * Are we in the middle of do_coredump?
2081 * If so and our tracer is also part of the coredump stopping
2082 * is a deadlock situation, and pointless because our tracer
2083 * is dead so don't allow us to stop.
2084 * If SIGKILL was already sent before the caller unlocked
2085 * ->siglock we must see ->core_state != NULL. Otherwise it
2086 * is safe to enter schedule().
2087 *
2088 * This is almost outdated, a task with the pending SIGKILL can't
2089 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
2090 * after SIGKILL was already dequeued.
2091 */
2092 if (unlikely(current->mm->core_state) &&
2093 unlikely(current->mm == current->parent->mm))
2094 return false;
2095
2096 return true;
2097}
2098
2099/*
2100 * Return non-zero if there is a SIGKILL that should be waking us up.
2101 * Called with the siglock held.
2102 */
2103static bool sigkill_pending(struct task_struct *tsk)
2104{
2105 return sigismember(&tsk->pending.signal, SIGKILL) ||
2106 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
2107}
2108
2109/*
2110 * This must be called with current->sighand->siglock held.
2111 *
2112 * This should be the path for all ptrace stops.
2113 * We always set current->last_siginfo while stopped here.
2114 * That makes it a way to test a stopped process for
2115 * being ptrace-stopped vs being job-control-stopped.
2116 *
2117 * If we actually decide not to stop at all because the tracer
2118 * is gone, we keep current->exit_code unless clear_code.
2119 */
2120static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
2121 __releases(¤t->sighand->siglock)
2122 __acquires(¤t->sighand->siglock)
2123{
2124 bool gstop_done = false;
2125
2126 if (arch_ptrace_stop_needed(exit_code, info)) {
2127 /*
2128 * The arch code has something special to do before a
2129 * ptrace stop. This is allowed to block, e.g. for faults
2130 * on user stack pages. We can't keep the siglock while
2131 * calling arch_ptrace_stop, so we must release it now.
2132 * To preserve proper semantics, we must do this before
2133 * any signal bookkeeping like checking group_stop_count.
2134 * Meanwhile, a SIGKILL could come in before we retake the
2135 * siglock. That must prevent us from sleeping in TASK_TRACED.
2136 * So after regaining the lock, we must check for SIGKILL.
2137 */
2138 spin_unlock_irq(¤t->sighand->siglock);
2139 arch_ptrace_stop(exit_code, info);
2140 spin_lock_irq(¤t->sighand->siglock);
2141 if (sigkill_pending(current))
2142 return;
2143 }
2144
2145 set_special_state(TASK_TRACED);
2146
2147 /*
2148 * We're committing to trapping. TRACED should be visible before
2149 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2150 * Also, transition to TRACED and updates to ->jobctl should be
2151 * atomic with respect to siglock and should be done after the arch
2152 * hook as siglock is released and regrabbed across it.
2153 *
2154 * TRACER TRACEE
2155 *
2156 * ptrace_attach()
2157 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2158 * do_wait()
2159 * set_current_state() smp_wmb();
2160 * ptrace_do_wait()
2161 * wait_task_stopped()
2162 * task_stopped_code()
2163 * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2164 */
2165 smp_wmb();
2166
2167 current->last_siginfo = info;
2168 current->exit_code = exit_code;
2169
2170 /*
2171 * If @why is CLD_STOPPED, we're trapping to participate in a group
2172 * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2173 * across siglock relocks since INTERRUPT was scheduled, PENDING
2174 * could be clear now. We act as if SIGCONT is received after
2175 * TASK_TRACED is entered - ignore it.
2176 */
2177 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2178 gstop_done = task_participate_group_stop(current);
2179
2180 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2181 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2182 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2183 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2184
2185 /* entering a trap, clear TRAPPING */
2186 task_clear_jobctl_trapping(current);
2187
2188 spin_unlock_irq(¤t->sighand->siglock);
2189 read_lock(&tasklist_lock);
2190 if (may_ptrace_stop()) {
2191 /*
2192 * Notify parents of the stop.
2193 *
2194 * While ptraced, there are two parents - the ptracer and
2195 * the real_parent of the group_leader. The ptracer should
2196 * know about every stop while the real parent is only
2197 * interested in the completion of group stop. The states
2198 * for the two don't interact with each other. Notify
2199 * separately unless they're gonna be duplicates.
2200 */
2201 do_notify_parent_cldstop(current, true, why);
2202 if (gstop_done && ptrace_reparented(current))
2203 do_notify_parent_cldstop(current, false, why);
2204
2205 /*
2206 * Don't want to allow preemption here, because
2207 * sys_ptrace() needs this task to be inactive.
2208 *
2209 * XXX: implement read_unlock_no_resched().
2210 */
2211 preempt_disable();
2212 read_unlock(&tasklist_lock);
2213 cgroup_enter_frozen();
2214 preempt_enable_no_resched();
2215 freezable_schedule();
2216 cgroup_leave_frozen(true);
2217 } else {
2218 /*
2219 * By the time we got the lock, our tracer went away.
2220 * Don't drop the lock yet, another tracer may come.
2221 *
2222 * If @gstop_done, the ptracer went away between group stop
2223 * completion and here. During detach, it would have set
2224 * JOBCTL_STOP_PENDING on us and we'll re-enter
2225 * TASK_STOPPED in do_signal_stop() on return, so notifying
2226 * the real parent of the group stop completion is enough.
2227 */
2228 if (gstop_done)
2229 do_notify_parent_cldstop(current, false, why);
2230
2231 /* tasklist protects us from ptrace_freeze_traced() */
2232 __set_current_state(TASK_RUNNING);
2233 if (clear_code)
2234 current->exit_code = 0;
2235 read_unlock(&tasklist_lock);
2236 }
2237
2238 /*
2239 * We are back. Now reacquire the siglock before touching
2240 * last_siginfo, so that we are sure to have synchronized with
2241 * any signal-sending on another CPU that wants to examine it.
2242 */
2243 spin_lock_irq(¤t->sighand->siglock);
2244 current->last_siginfo = NULL;
2245
2246 /* LISTENING can be set only during STOP traps, clear it */
2247 current->jobctl &= ~JOBCTL_LISTENING;
2248
2249 /*
2250 * Queued signals ignored us while we were stopped for tracing.
2251 * So check for any that we should take before resuming user mode.
2252 * This sets TIF_SIGPENDING, but never clears it.
2253 */
2254 recalc_sigpending_tsk(current);
2255}
2256
2257static void ptrace_do_notify(int signr, int exit_code, int why)
2258{
2259 kernel_siginfo_t info;
2260
2261 clear_siginfo(&info);
2262 info.si_signo = signr;
2263 info.si_code = exit_code;
2264 info.si_pid = task_pid_vnr(current);
2265 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2266
2267 /* Let the debugger run. */
2268 ptrace_stop(exit_code, why, 1, &info);
2269}
2270
2271void ptrace_notify(int exit_code)
2272{
2273 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2274 if (unlikely(current->task_works))
2275 task_work_run();
2276
2277 spin_lock_irq(¤t->sighand->siglock);
2278 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2279 spin_unlock_irq(¤t->sighand->siglock);
2280}
2281
2282/**
2283 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2284 * @signr: signr causing group stop if initiating
2285 *
2286 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2287 * and participate in it. If already set, participate in the existing
2288 * group stop. If participated in a group stop (and thus slept), %true is
2289 * returned with siglock released.
2290 *
2291 * If ptraced, this function doesn't handle stop itself. Instead,
2292 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2293 * untouched. The caller must ensure that INTERRUPT trap handling takes
2294 * places afterwards.
2295 *
2296 * CONTEXT:
2297 * Must be called with @current->sighand->siglock held, which is released
2298 * on %true return.
2299 *
2300 * RETURNS:
2301 * %false if group stop is already cancelled or ptrace trap is scheduled.
2302 * %true if participated in group stop.
2303 */
2304static bool do_signal_stop(int signr)
2305 __releases(¤t->sighand->siglock)
2306{
2307 struct signal_struct *sig = current->signal;
2308
2309 if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2310 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2311 struct task_struct *t;
2312
2313 /* signr will be recorded in task->jobctl for retries */
2314 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2315
2316 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2317 unlikely(signal_group_exit(sig)))
2318 return false;
2319 /*
2320 * There is no group stop already in progress. We must
2321 * initiate one now.
2322 *
2323 * While ptraced, a task may be resumed while group stop is
2324 * still in effect and then receive a stop signal and
2325 * initiate another group stop. This deviates from the
2326 * usual behavior as two consecutive stop signals can't
2327 * cause two group stops when !ptraced. That is why we
2328 * also check !task_is_stopped(t) below.
2329 *
2330 * The condition can be distinguished by testing whether
2331 * SIGNAL_STOP_STOPPED is already set. Don't generate
2332 * group_exit_code in such case.
2333 *
2334 * This is not necessary for SIGNAL_STOP_CONTINUED because
2335 * an intervening stop signal is required to cause two
2336 * continued events regardless of ptrace.
2337 */
2338 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2339 sig->group_exit_code = signr;
2340
2341 sig->group_stop_count = 0;
2342
2343 if (task_set_jobctl_pending(current, signr | gstop))
2344 sig->group_stop_count++;
2345
2346 t = current;
2347 while_each_thread(current, t) {
2348 /*
2349 * Setting state to TASK_STOPPED for a group
2350 * stop is always done with the siglock held,
2351 * so this check has no races.
2352 */
2353 if (!task_is_stopped(t) &&
2354 task_set_jobctl_pending(t, signr | gstop)) {
2355 sig->group_stop_count++;
2356 if (likely(!(t->ptrace & PT_SEIZED)))
2357 signal_wake_up(t, 0);
2358 else
2359 ptrace_trap_notify(t);
2360 }
2361 }
2362 }
2363
2364 if (likely(!current->ptrace)) {
2365 int notify = 0;
2366
2367 /*
2368 * If there are no other threads in the group, or if there
2369 * is a group stop in progress and we are the last to stop,
2370 * report to the parent.
2371 */
2372 if (task_participate_group_stop(current))
2373 notify = CLD_STOPPED;
2374
2375 set_special_state(TASK_STOPPED);
2376 spin_unlock_irq(¤t->sighand->siglock);
2377
2378 /*
2379 * Notify the parent of the group stop completion. Because
2380 * we're not holding either the siglock or tasklist_lock
2381 * here, ptracer may attach inbetween; however, this is for
2382 * group stop and should always be delivered to the real
2383 * parent of the group leader. The new ptracer will get
2384 * its notification when this task transitions into
2385 * TASK_TRACED.
2386 */
2387 if (notify) {
2388 read_lock(&tasklist_lock);
2389 do_notify_parent_cldstop(current, false, notify);
2390 read_unlock(&tasklist_lock);
2391 }
2392
2393 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2394 cgroup_enter_frozen();
2395 freezable_schedule();
2396 return true;
2397 } else {
2398 /*
2399 * While ptraced, group stop is handled by STOP trap.
2400 * Schedule it and let the caller deal with it.
2401 */
2402 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2403 return false;
2404 }
2405}
2406
2407/**
2408 * do_jobctl_trap - take care of ptrace jobctl traps
2409 *
2410 * When PT_SEIZED, it's used for both group stop and explicit
2411 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2412 * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2413 * the stop signal; otherwise, %SIGTRAP.
2414 *
2415 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2416 * number as exit_code and no siginfo.
2417 *
2418 * CONTEXT:
2419 * Must be called with @current->sighand->siglock held, which may be
2420 * released and re-acquired before returning with intervening sleep.
2421 */
2422static void do_jobctl_trap(void)
2423{
2424 struct signal_struct *signal = current->signal;
2425 int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2426
2427 if (current->ptrace & PT_SEIZED) {
2428 if (!signal->group_stop_count &&
2429 !(signal->flags & SIGNAL_STOP_STOPPED))
2430 signr = SIGTRAP;
2431 WARN_ON_ONCE(!signr);
2432 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2433 CLD_STOPPED);
2434 } else {
2435 WARN_ON_ONCE(!signr);
2436 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2437 current->exit_code = 0;
2438 }
2439}
2440
2441/**
2442 * do_freezer_trap - handle the freezer jobctl trap
2443 *
2444 * Puts the task into frozen state, if only the task is not about to quit.
2445 * In this case it drops JOBCTL_TRAP_FREEZE.
2446 *
2447 * CONTEXT:
2448 * Must be called with @current->sighand->siglock held,
2449 * which is always released before returning.
2450 */
2451static void do_freezer_trap(void)
2452 __releases(¤t->sighand->siglock)
2453{
2454 /*
2455 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2456 * let's make another loop to give it a chance to be handled.
2457 * In any case, we'll return back.
2458 */
2459 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2460 JOBCTL_TRAP_FREEZE) {
2461 spin_unlock_irq(¤t->sighand->siglock);
2462 return;
2463 }
2464
2465 /*
2466 * Now we're sure that there is no pending fatal signal and no
2467 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2468 * immediately (if there is a non-fatal signal pending), and
2469 * put the task into sleep.
2470 */
2471 __set_current_state(TASK_INTERRUPTIBLE);
2472 clear_thread_flag(TIF_SIGPENDING);
2473 spin_unlock_irq(¤t->sighand->siglock);
2474 cgroup_enter_frozen();
2475 freezable_schedule();
2476}
2477
2478static int ptrace_signal(int signr, kernel_siginfo_t *info)
2479{
2480 /*
2481 * We do not check sig_kernel_stop(signr) but set this marker
2482 * unconditionally because we do not know whether debugger will
2483 * change signr. This flag has no meaning unless we are going
2484 * to stop after return from ptrace_stop(). In this case it will
2485 * be checked in do_signal_stop(), we should only stop if it was
2486 * not cleared by SIGCONT while we were sleeping. See also the
2487 * comment in dequeue_signal().
2488 */
2489 current->jobctl |= JOBCTL_STOP_DEQUEUED;
2490 ptrace_stop(signr, CLD_TRAPPED, 0, info);
2491
2492 /* We're back. Did the debugger cancel the sig? */
2493 signr = current->exit_code;
2494 if (signr == 0)
2495 return signr;
2496
2497 current->exit_code = 0;
2498
2499 /*
2500 * Update the siginfo structure if the signal has
2501 * changed. If the debugger wanted something
2502 * specific in the siginfo structure then it should
2503 * have updated *info via PTRACE_SETSIGINFO.
2504 */
2505 if (signr != info->si_signo) {
2506 clear_siginfo(info);
2507 info->si_signo = signr;
2508 info->si_errno = 0;
2509 info->si_code = SI_USER;
2510 rcu_read_lock();
2511 info->si_pid = task_pid_vnr(current->parent);
2512 info->si_uid = from_kuid_munged(current_user_ns(),
2513 task_uid(current->parent));
2514 rcu_read_unlock();
2515 }
2516
2517 /* If the (new) signal is now blocked, requeue it. */
2518 if (sigismember(¤t->blocked, signr)) {
2519 send_signal(signr, info, current, PIDTYPE_PID);
2520 signr = 0;
2521 }
2522
2523 return signr;
2524}
2525
2526bool get_signal(struct ksignal *ksig)
2527{
2528 struct sighand_struct *sighand = current->sighand;
2529 struct signal_struct *signal = current->signal;
2530 int signr;
2531
2532 if (unlikely(uprobe_deny_signal()))
2533 return false;
2534
2535 /*
2536 * Do this once, we can't return to user-mode if freezing() == T.
2537 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2538 * thus do not need another check after return.
2539 */
2540 try_to_freeze();
2541
2542relock:
2543 spin_lock_irq(&sighand->siglock);
2544 /*
2545 * Make sure we can safely read ->jobctl() in task_work add. As Oleg
2546 * states:
2547 *
2548 * It pairs with mb (implied by cmpxchg) before READ_ONCE. So we
2549 * roughly have
2550 *
2551 * task_work_add: get_signal:
2552 * STORE(task->task_works, new_work); STORE(task->jobctl);
2553 * mb(); mb();
2554 * LOAD(task->jobctl); LOAD(task->task_works);
2555 *
2556 * and we can rely on STORE-MB-LOAD [ in task_work_add].
2557 */
2558 smp_store_mb(current->jobctl, current->jobctl & ~JOBCTL_TASK_WORK);
2559 if (unlikely(current->task_works)) {
2560 spin_unlock_irq(&sighand->siglock);
2561 task_work_run();
2562 goto relock;
2563 }
2564
2565 /*
2566 * Every stopped thread goes here after wakeup. Check to see if
2567 * we should notify the parent, prepare_signal(SIGCONT) encodes
2568 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2569 */
2570 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2571 int why;
2572
2573 if (signal->flags & SIGNAL_CLD_CONTINUED)
2574 why = CLD_CONTINUED;
2575 else
2576 why = CLD_STOPPED;
2577
2578 signal->flags &= ~SIGNAL_CLD_MASK;
2579
2580 spin_unlock_irq(&sighand->siglock);
2581
2582 /*
2583 * Notify the parent that we're continuing. This event is
2584 * always per-process and doesn't make whole lot of sense
2585 * for ptracers, who shouldn't consume the state via
2586 * wait(2) either, but, for backward compatibility, notify
2587 * the ptracer of the group leader too unless it's gonna be
2588 * a duplicate.
2589 */
2590 read_lock(&tasklist_lock);
2591 do_notify_parent_cldstop(current, false, why);
2592
2593 if (ptrace_reparented(current->group_leader))
2594 do_notify_parent_cldstop(current->group_leader,
2595 true, why);
2596 read_unlock(&tasklist_lock);
2597
2598 goto relock;
2599 }
2600
2601 /* Has this task already been marked for death? */
2602 if (signal_group_exit(signal)) {
2603 ksig->info.si_signo = signr = SIGKILL;
2604 sigdelset(¤t->pending.signal, SIGKILL);
2605 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2606 &sighand->action[SIGKILL - 1]);
2607 recalc_sigpending();
2608 goto fatal;
2609 }
2610
2611 for (;;) {
2612 struct k_sigaction *ka;
2613
2614 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2615 do_signal_stop(0))
2616 goto relock;
2617
2618 if (unlikely(current->jobctl &
2619 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2620 if (current->jobctl & JOBCTL_TRAP_MASK) {
2621 do_jobctl_trap();
2622 spin_unlock_irq(&sighand->siglock);
2623 } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2624 do_freezer_trap();
2625
2626 goto relock;
2627 }
2628
2629 /*
2630 * If the task is leaving the frozen state, let's update
2631 * cgroup counters and reset the frozen bit.
2632 */
2633 if (unlikely(cgroup_task_frozen(current))) {
2634 spin_unlock_irq(&sighand->siglock);
2635 cgroup_leave_frozen(false);
2636 goto relock;
2637 }
2638
2639 /*
2640 * Signals generated by the execution of an instruction
2641 * need to be delivered before any other pending signals
2642 * so that the instruction pointer in the signal stack
2643 * frame points to the faulting instruction.
2644 */
2645 signr = dequeue_synchronous_signal(&ksig->info);
2646 if (!signr)
2647 signr = dequeue_signal(current, ¤t->blocked, &ksig->info);
2648
2649 if (!signr)
2650 break; /* will return 0 */
2651
2652 if (unlikely(current->ptrace) && signr != SIGKILL) {
2653 signr = ptrace_signal(signr, &ksig->info);
2654 if (!signr)
2655 continue;
2656 }
2657
2658 ka = &sighand->action[signr-1];
2659
2660 /* Trace actually delivered signals. */
2661 trace_signal_deliver(signr, &ksig->info, ka);
2662
2663 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2664 continue;
2665 if (ka->sa.sa_handler != SIG_DFL) {
2666 /* Run the handler. */
2667 ksig->ka = *ka;
2668
2669 if (ka->sa.sa_flags & SA_ONESHOT)
2670 ka->sa.sa_handler = SIG_DFL;
2671
2672 break; /* will return non-zero "signr" value */
2673 }
2674
2675 /*
2676 * Now we are doing the default action for this signal.
2677 */
2678 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2679 continue;
2680
2681 /*
2682 * Global init gets no signals it doesn't want.
2683 * Container-init gets no signals it doesn't want from same
2684 * container.
2685 *
2686 * Note that if global/container-init sees a sig_kernel_only()
2687 * signal here, the signal must have been generated internally
2688 * or must have come from an ancestor namespace. In either
2689 * case, the signal cannot be dropped.
2690 */
2691 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2692 !sig_kernel_only(signr))
2693 continue;
2694
2695 if (sig_kernel_stop(signr)) {
2696 /*
2697 * The default action is to stop all threads in
2698 * the thread group. The job control signals
2699 * do nothing in an orphaned pgrp, but SIGSTOP
2700 * always works. Note that siglock needs to be
2701 * dropped during the call to is_orphaned_pgrp()
2702 * because of lock ordering with tasklist_lock.
2703 * This allows an intervening SIGCONT to be posted.
2704 * We need to check for that and bail out if necessary.
2705 */
2706 if (signr != SIGSTOP) {
2707 spin_unlock_irq(&sighand->siglock);
2708
2709 /* signals can be posted during this window */
2710
2711 if (is_current_pgrp_orphaned())
2712 goto relock;
2713
2714 spin_lock_irq(&sighand->siglock);
2715 }
2716
2717 if (likely(do_signal_stop(ksig->info.si_signo))) {
2718 /* It released the siglock. */
2719 goto relock;
2720 }
2721
2722 /*
2723 * We didn't actually stop, due to a race
2724 * with SIGCONT or something like that.
2725 */
2726 continue;
2727 }
2728
2729 fatal:
2730 spin_unlock_irq(&sighand->siglock);
2731 if (unlikely(cgroup_task_frozen(current)))
2732 cgroup_leave_frozen(true);
2733
2734 /*
2735 * Anything else is fatal, maybe with a core dump.
2736 */
2737 current->flags |= PF_SIGNALED;
2738
2739 if (sig_kernel_coredump(signr)) {
2740 if (print_fatal_signals)
2741 print_fatal_signal(ksig->info.si_signo);
2742 proc_coredump_connector(current);
2743 /*
2744 * If it was able to dump core, this kills all
2745 * other threads in the group and synchronizes with
2746 * their demise. If we lost the race with another
2747 * thread getting here, it set group_exit_code
2748 * first and our do_group_exit call below will use
2749 * that value and ignore the one we pass it.
2750 */
2751 do_coredump(&ksig->info);
2752 }
2753
2754 /*
2755 * Death signals, no core dump.
2756 */
2757 do_group_exit(ksig->info.si_signo);
2758 /* NOTREACHED */
2759 }
2760 spin_unlock_irq(&sighand->siglock);
2761
2762 ksig->sig = signr;
2763 return ksig->sig > 0;
2764}
2765
2766/**
2767 * signal_delivered -
2768 * @ksig: kernel signal struct
2769 * @stepping: nonzero if debugger single-step or block-step in use
2770 *
2771 * This function should be called when a signal has successfully been
2772 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2773 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2774 * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2775 */
2776static void signal_delivered(struct ksignal *ksig, int stepping)
2777{
2778 sigset_t blocked;
2779
2780 /* A signal was successfully delivered, and the
2781 saved sigmask was stored on the signal frame,
2782 and will be restored by sigreturn. So we can
2783 simply clear the restore sigmask flag. */
2784 clear_restore_sigmask();
2785
2786 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2787 if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2788 sigaddset(&blocked, ksig->sig);
2789 set_current_blocked(&blocked);
2790 tracehook_signal_handler(stepping);
2791}
2792
2793void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2794{
2795 if (failed)
2796 force_sigsegv(ksig->sig);
2797 else
2798 signal_delivered(ksig, stepping);
2799}
2800
2801/*
2802 * It could be that complete_signal() picked us to notify about the
2803 * group-wide signal. Other threads should be notified now to take
2804 * the shared signals in @which since we will not.
2805 */
2806static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2807{
2808 sigset_t retarget;
2809 struct task_struct *t;
2810
2811 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2812 if (sigisemptyset(&retarget))
2813 return;
2814
2815 t = tsk;
2816 while_each_thread(tsk, t) {
2817 if (t->flags & PF_EXITING)
2818 continue;
2819
2820 if (!has_pending_signals(&retarget, &t->blocked))
2821 continue;
2822 /* Remove the signals this thread can handle. */
2823 sigandsets(&retarget, &retarget, &t->blocked);
2824
2825 if (!signal_pending(t))
2826 signal_wake_up(t, 0);
2827
2828 if (sigisemptyset(&retarget))
2829 break;
2830 }
2831}
2832
2833void exit_signals(struct task_struct *tsk)
2834{
2835 int group_stop = 0;
2836 sigset_t unblocked;
2837
2838 /*
2839 * @tsk is about to have PF_EXITING set - lock out users which
2840 * expect stable threadgroup.
2841 */
2842 cgroup_threadgroup_change_begin(tsk);
2843
2844 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2845 tsk->flags |= PF_EXITING;
2846 cgroup_threadgroup_change_end(tsk);
2847 return;
2848 }
2849
2850 spin_lock_irq(&tsk->sighand->siglock);
2851 /*
2852 * From now this task is not visible for group-wide signals,
2853 * see wants_signal(), do_signal_stop().
2854 */
2855 tsk->flags |= PF_EXITING;
2856
2857 cgroup_threadgroup_change_end(tsk);
2858
2859 if (!signal_pending(tsk))
2860 goto out;
2861
2862 unblocked = tsk->blocked;
2863 signotset(&unblocked);
2864 retarget_shared_pending(tsk, &unblocked);
2865
2866 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2867 task_participate_group_stop(tsk))
2868 group_stop = CLD_STOPPED;
2869out:
2870 spin_unlock_irq(&tsk->sighand->siglock);
2871
2872 /*
2873 * If group stop has completed, deliver the notification. This
2874 * should always go to the real parent of the group leader.
2875 */
2876 if (unlikely(group_stop)) {
2877 read_lock(&tasklist_lock);
2878 do_notify_parent_cldstop(tsk, false, group_stop);
2879 read_unlock(&tasklist_lock);
2880 }
2881}
2882
2883/*
2884 * System call entry points.
2885 */
2886
2887/**
2888 * sys_restart_syscall - restart a system call
2889 */
2890SYSCALL_DEFINE0(restart_syscall)
2891{
2892 struct restart_block *restart = ¤t->restart_block;
2893 return restart->fn(restart);
2894}
2895
2896long do_no_restart_syscall(struct restart_block *param)
2897{
2898 return -EINTR;
2899}
2900
2901static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2902{
2903 if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2904 sigset_t newblocked;
2905 /* A set of now blocked but previously unblocked signals. */
2906 sigandnsets(&newblocked, newset, ¤t->blocked);
2907 retarget_shared_pending(tsk, &newblocked);
2908 }
2909 tsk->blocked = *newset;
2910 recalc_sigpending();
2911}
2912
2913/**
2914 * set_current_blocked - change current->blocked mask
2915 * @newset: new mask
2916 *
2917 * It is wrong to change ->blocked directly, this helper should be used
2918 * to ensure the process can't miss a shared signal we are going to block.
2919 */
2920void set_current_blocked(sigset_t *newset)
2921{
2922 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2923 __set_current_blocked(newset);
2924}
2925
2926void __set_current_blocked(const sigset_t *newset)
2927{
2928 struct task_struct *tsk = current;
2929
2930 /*
2931 * In case the signal mask hasn't changed, there is nothing we need
2932 * to do. The current->blocked shouldn't be modified by other task.
2933 */
2934 if (sigequalsets(&tsk->blocked, newset))
2935 return;
2936
2937 spin_lock_irq(&tsk->sighand->siglock);
2938 __set_task_blocked(tsk, newset);
2939 spin_unlock_irq(&tsk->sighand->siglock);
2940}
2941
2942/*
2943 * This is also useful for kernel threads that want to temporarily
2944 * (or permanently) block certain signals.
2945 *
2946 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2947 * interface happily blocks "unblockable" signals like SIGKILL
2948 * and friends.
2949 */
2950int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2951{
2952 struct task_struct *tsk = current;
2953 sigset_t newset;
2954
2955 /* Lockless, only current can change ->blocked, never from irq */
2956 if (oldset)
2957 *oldset = tsk->blocked;
2958
2959 switch (how) {
2960 case SIG_BLOCK:
2961 sigorsets(&newset, &tsk->blocked, set);
2962 break;
2963 case SIG_UNBLOCK:
2964 sigandnsets(&newset, &tsk->blocked, set);
2965 break;
2966 case SIG_SETMASK:
2967 newset = *set;
2968 break;
2969 default:
2970 return -EINVAL;
2971 }
2972
2973 __set_current_blocked(&newset);
2974 return 0;
2975}
2976EXPORT_SYMBOL(sigprocmask);
2977
2978/*
2979 * The api helps set app-provided sigmasks.
2980 *
2981 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
2982 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
2983 *
2984 * Note that it does set_restore_sigmask() in advance, so it must be always
2985 * paired with restore_saved_sigmask_unless() before return from syscall.
2986 */
2987int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
2988{
2989 sigset_t kmask;
2990
2991 if (!umask)
2992 return 0;
2993 if (sigsetsize != sizeof(sigset_t))
2994 return -EINVAL;
2995 if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
2996 return -EFAULT;
2997
2998 set_restore_sigmask();
2999 current->saved_sigmask = current->blocked;
3000 set_current_blocked(&kmask);
3001
3002 return 0;
3003}
3004
3005#ifdef CONFIG_COMPAT
3006int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3007 size_t sigsetsize)
3008{
3009 sigset_t kmask;
3010
3011 if (!umask)
3012 return 0;
3013 if (sigsetsize != sizeof(compat_sigset_t))
3014 return -EINVAL;
3015 if (get_compat_sigset(&kmask, umask))
3016 return -EFAULT;
3017
3018 set_restore_sigmask();
3019 current->saved_sigmask = current->blocked;
3020 set_current_blocked(&kmask);
3021
3022 return 0;
3023}
3024#endif
3025
3026/**
3027 * sys_rt_sigprocmask - change the list of currently blocked signals
3028 * @how: whether to add, remove, or set signals
3029 * @nset: stores pending signals
3030 * @oset: previous value of signal mask if non-null
3031 * @sigsetsize: size of sigset_t type
3032 */
3033SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3034 sigset_t __user *, oset, size_t, sigsetsize)
3035{
3036 sigset_t old_set, new_set;
3037 int error;
3038
3039 /* XXX: Don't preclude handling different sized sigset_t's. */
3040 if (sigsetsize != sizeof(sigset_t))
3041 return -EINVAL;
3042
3043 old_set = current->blocked;
3044
3045 if (nset) {
3046 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3047 return -EFAULT;
3048 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3049
3050 error = sigprocmask(how, &new_set, NULL);
3051 if (error)
3052 return error;
3053 }
3054
3055 if (oset) {
3056 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3057 return -EFAULT;
3058 }
3059
3060 return 0;
3061}
3062
3063#ifdef CONFIG_COMPAT
3064COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3065 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3066{
3067 sigset_t old_set = current->blocked;
3068
3069 /* XXX: Don't preclude handling different sized sigset_t's. */
3070 if (sigsetsize != sizeof(sigset_t))
3071 return -EINVAL;
3072
3073 if (nset) {
3074 sigset_t new_set;
3075 int error;
3076 if (get_compat_sigset(&new_set, nset))
3077 return -EFAULT;
3078 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3079
3080 error = sigprocmask(how, &new_set, NULL);
3081 if (error)
3082 return error;
3083 }
3084 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3085}
3086#endif
3087
3088static void do_sigpending(sigset_t *set)
3089{
3090 spin_lock_irq(¤t->sighand->siglock);
3091 sigorsets(set, ¤t->pending.signal,
3092 ¤t->signal->shared_pending.signal);
3093 spin_unlock_irq(¤t->sighand->siglock);
3094
3095 /* Outside the lock because only this thread touches it. */
3096 sigandsets(set, ¤t->blocked, set);
3097}
3098
3099/**
3100 * sys_rt_sigpending - examine a pending signal that has been raised
3101 * while blocked
3102 * @uset: stores pending signals
3103 * @sigsetsize: size of sigset_t type or larger
3104 */
3105SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3106{
3107 sigset_t set;
3108
3109 if (sigsetsize > sizeof(*uset))
3110 return -EINVAL;
3111
3112 do_sigpending(&set);
3113
3114 if (copy_to_user(uset, &set, sigsetsize))
3115 return -EFAULT;
3116
3117 return 0;
3118}
3119
3120#ifdef CONFIG_COMPAT
3121COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3122 compat_size_t, sigsetsize)
3123{
3124 sigset_t set;
3125
3126 if (sigsetsize > sizeof(*uset))
3127 return -EINVAL;
3128
3129 do_sigpending(&set);
3130
3131 return put_compat_sigset(uset, &set, sigsetsize);
3132}
3133#endif
3134
3135static const struct {
3136 unsigned char limit, layout;
3137} sig_sicodes[] = {
3138 [SIGILL] = { NSIGILL, SIL_FAULT },
3139 [SIGFPE] = { NSIGFPE, SIL_FAULT },
3140 [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3141 [SIGBUS] = { NSIGBUS, SIL_FAULT },
3142 [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3143#if defined(SIGEMT)
3144 [SIGEMT] = { NSIGEMT, SIL_FAULT },
3145#endif
3146 [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3147 [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3148 [SIGSYS] = { NSIGSYS, SIL_SYS },
3149};
3150
3151static bool known_siginfo_layout(unsigned sig, int si_code)
3152{
3153 if (si_code == SI_KERNEL)
3154 return true;
3155 else if ((si_code > SI_USER)) {
3156 if (sig_specific_sicodes(sig)) {
3157 if (si_code <= sig_sicodes[sig].limit)
3158 return true;
3159 }
3160 else if (si_code <= NSIGPOLL)
3161 return true;
3162 }
3163 else if (si_code >= SI_DETHREAD)
3164 return true;
3165 else if (si_code == SI_ASYNCNL)
3166 return true;
3167 return false;
3168}
3169
3170enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3171{
3172 enum siginfo_layout layout = SIL_KILL;
3173 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3174 if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3175 (si_code <= sig_sicodes[sig].limit)) {
3176 layout = sig_sicodes[sig].layout;
3177 /* Handle the exceptions */
3178 if ((sig == SIGBUS) &&
3179 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3180 layout = SIL_FAULT_MCEERR;
3181 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3182 layout = SIL_FAULT_BNDERR;
3183#ifdef SEGV_PKUERR
3184 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3185 layout = SIL_FAULT_PKUERR;
3186#endif
3187 }
3188 else if (si_code <= NSIGPOLL)
3189 layout = SIL_POLL;
3190 } else {
3191 if (si_code == SI_TIMER)
3192 layout = SIL_TIMER;
3193 else if (si_code == SI_SIGIO)
3194 layout = SIL_POLL;
3195 else if (si_code < 0)
3196 layout = SIL_RT;
3197 }
3198 return layout;
3199}
3200
3201static inline char __user *si_expansion(const siginfo_t __user *info)
3202{
3203 return ((char __user *)info) + sizeof(struct kernel_siginfo);
3204}
3205
3206int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3207{
3208 char __user *expansion = si_expansion(to);
3209 if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3210 return -EFAULT;
3211 if (clear_user(expansion, SI_EXPANSION_SIZE))
3212 return -EFAULT;
3213 return 0;
3214}
3215
3216static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3217 const siginfo_t __user *from)
3218{
3219 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3220 char __user *expansion = si_expansion(from);
3221 char buf[SI_EXPANSION_SIZE];
3222 int i;
3223 /*
3224 * An unknown si_code might need more than
3225 * sizeof(struct kernel_siginfo) bytes. Verify all of the
3226 * extra bytes are 0. This guarantees copy_siginfo_to_user
3227 * will return this data to userspace exactly.
3228 */
3229 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3230 return -EFAULT;
3231 for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3232 if (buf[i] != 0)
3233 return -E2BIG;
3234 }
3235 }
3236 return 0;
3237}
3238
3239static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3240 const siginfo_t __user *from)
3241{
3242 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3243 return -EFAULT;
3244 to->si_signo = signo;
3245 return post_copy_siginfo_from_user(to, from);
3246}
3247
3248int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3249{
3250 if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3251 return -EFAULT;
3252 return post_copy_siginfo_from_user(to, from);
3253}
3254
3255#ifdef CONFIG_COMPAT
3256/**
3257 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3258 * @to: compat siginfo destination
3259 * @from: kernel siginfo source
3260 *
3261 * Note: This function does not work properly for the SIGCHLD on x32, but
3262 * fortunately it doesn't have to. The only valid callers for this function are
3263 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3264 * The latter does not care because SIGCHLD will never cause a coredump.
3265 */
3266void copy_siginfo_to_external32(struct compat_siginfo *to,
3267 const struct kernel_siginfo *from)
3268{
3269 memset(to, 0, sizeof(*to));
3270
3271 to->si_signo = from->si_signo;
3272 to->si_errno = from->si_errno;
3273 to->si_code = from->si_code;
3274 switch(siginfo_layout(from->si_signo, from->si_code)) {
3275 case SIL_KILL:
3276 to->si_pid = from->si_pid;
3277 to->si_uid = from->si_uid;
3278 break;
3279 case SIL_TIMER:
3280 to->si_tid = from->si_tid;
3281 to->si_overrun = from->si_overrun;
3282 to->si_int = from->si_int;
3283 break;
3284 case SIL_POLL:
3285 to->si_band = from->si_band;
3286 to->si_fd = from->si_fd;
3287 break;
3288 case SIL_FAULT:
3289 to->si_addr = ptr_to_compat(from->si_addr);
3290#ifdef __ARCH_SI_TRAPNO
3291 to->si_trapno = from->si_trapno;
3292#endif
3293 break;
3294 case SIL_FAULT_MCEERR:
3295 to->si_addr = ptr_to_compat(from->si_addr);
3296#ifdef __ARCH_SI_TRAPNO
3297 to->si_trapno = from->si_trapno;
3298#endif
3299 to->si_addr_lsb = from->si_addr_lsb;
3300 break;
3301 case SIL_FAULT_BNDERR:
3302 to->si_addr = ptr_to_compat(from->si_addr);
3303#ifdef __ARCH_SI_TRAPNO
3304 to->si_trapno = from->si_trapno;
3305#endif
3306 to->si_lower = ptr_to_compat(from->si_lower);
3307 to->si_upper = ptr_to_compat(from->si_upper);
3308 break;
3309 case SIL_FAULT_PKUERR:
3310 to->si_addr = ptr_to_compat(from->si_addr);
3311#ifdef __ARCH_SI_TRAPNO
3312 to->si_trapno = from->si_trapno;
3313#endif
3314 to->si_pkey = from->si_pkey;
3315 break;
3316 case SIL_CHLD:
3317 to->si_pid = from->si_pid;
3318 to->si_uid = from->si_uid;
3319 to->si_status = from->si_status;
3320 to->si_utime = from->si_utime;
3321 to->si_stime = from->si_stime;
3322 break;
3323 case SIL_RT:
3324 to->si_pid = from->si_pid;
3325 to->si_uid = from->si_uid;
3326 to->si_int = from->si_int;
3327 break;
3328 case SIL_SYS:
3329 to->si_call_addr = ptr_to_compat(from->si_call_addr);
3330 to->si_syscall = from->si_syscall;
3331 to->si_arch = from->si_arch;
3332 break;
3333 }
3334}
3335
3336int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3337 const struct kernel_siginfo *from)
3338{
3339 struct compat_siginfo new;
3340
3341 copy_siginfo_to_external32(&new, from);
3342 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3343 return -EFAULT;
3344 return 0;
3345}
3346
3347static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3348 const struct compat_siginfo *from)
3349{
3350 clear_siginfo(to);
3351 to->si_signo = from->si_signo;
3352 to->si_errno = from->si_errno;
3353 to->si_code = from->si_code;
3354 switch(siginfo_layout(from->si_signo, from->si_code)) {
3355 case SIL_KILL:
3356 to->si_pid = from->si_pid;
3357 to->si_uid = from->si_uid;
3358 break;
3359 case SIL_TIMER:
3360 to->si_tid = from->si_tid;
3361 to->si_overrun = from->si_overrun;
3362 to->si_int = from->si_int;
3363 break;
3364 case SIL_POLL:
3365 to->si_band = from->si_band;
3366 to->si_fd = from->si_fd;
3367 break;
3368 case SIL_FAULT:
3369 to->si_addr = compat_ptr(from->si_addr);
3370#ifdef __ARCH_SI_TRAPNO
3371 to->si_trapno = from->si_trapno;
3372#endif
3373 break;
3374 case SIL_FAULT_MCEERR:
3375 to->si_addr = compat_ptr(from->si_addr);
3376#ifdef __ARCH_SI_TRAPNO
3377 to->si_trapno = from->si_trapno;
3378#endif
3379 to->si_addr_lsb = from->si_addr_lsb;
3380 break;
3381 case SIL_FAULT_BNDERR:
3382 to->si_addr = compat_ptr(from->si_addr);
3383#ifdef __ARCH_SI_TRAPNO
3384 to->si_trapno = from->si_trapno;
3385#endif
3386 to->si_lower = compat_ptr(from->si_lower);
3387 to->si_upper = compat_ptr(from->si_upper);
3388 break;
3389 case SIL_FAULT_PKUERR:
3390 to->si_addr = compat_ptr(from->si_addr);
3391#ifdef __ARCH_SI_TRAPNO
3392 to->si_trapno = from->si_trapno;
3393#endif
3394 to->si_pkey = from->si_pkey;
3395 break;
3396 case SIL_CHLD:
3397 to->si_pid = from->si_pid;
3398 to->si_uid = from->si_uid;
3399 to->si_status = from->si_status;
3400#ifdef CONFIG_X86_X32_ABI
3401 if (in_x32_syscall()) {
3402 to->si_utime = from->_sifields._sigchld_x32._utime;
3403 to->si_stime = from->_sifields._sigchld_x32._stime;
3404 } else
3405#endif
3406 {
3407 to->si_utime = from->si_utime;
3408 to->si_stime = from->si_stime;
3409 }
3410 break;
3411 case SIL_RT:
3412 to->si_pid = from->si_pid;
3413 to->si_uid = from->si_uid;
3414 to->si_int = from->si_int;
3415 break;
3416 case SIL_SYS:
3417 to->si_call_addr = compat_ptr(from->si_call_addr);
3418 to->si_syscall = from->si_syscall;
3419 to->si_arch = from->si_arch;
3420 break;
3421 }
3422 return 0;
3423}
3424
3425static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3426 const struct compat_siginfo __user *ufrom)
3427{
3428 struct compat_siginfo from;
3429
3430 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3431 return -EFAULT;
3432
3433 from.si_signo = signo;
3434 return post_copy_siginfo_from_user32(to, &from);
3435}
3436
3437int copy_siginfo_from_user32(struct kernel_siginfo *to,
3438 const struct compat_siginfo __user *ufrom)
3439{
3440 struct compat_siginfo from;
3441
3442 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3443 return -EFAULT;
3444
3445 return post_copy_siginfo_from_user32(to, &from);
3446}
3447#endif /* CONFIG_COMPAT */
3448
3449/**
3450 * do_sigtimedwait - wait for queued signals specified in @which
3451 * @which: queued signals to wait for
3452 * @info: if non-null, the signal's siginfo is returned here
3453 * @ts: upper bound on process time suspension
3454 */
3455static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3456 const struct timespec64 *ts)
3457{
3458 ktime_t *to = NULL, timeout = KTIME_MAX;
3459 struct task_struct *tsk = current;
3460 sigset_t mask = *which;
3461 int sig, ret = 0;
3462
3463 if (ts) {
3464 if (!timespec64_valid(ts))
3465 return -EINVAL;
3466 timeout = timespec64_to_ktime(*ts);
3467 to = &timeout;
3468 }
3469
3470 /*
3471 * Invert the set of allowed signals to get those we want to block.
3472 */
3473 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3474 signotset(&mask);
3475
3476 spin_lock_irq(&tsk->sighand->siglock);
3477 sig = dequeue_signal(tsk, &mask, info);
3478 if (!sig && timeout) {
3479 /*
3480 * None ready, temporarily unblock those we're interested
3481 * while we are sleeping in so that we'll be awakened when
3482 * they arrive. Unblocking is always fine, we can avoid
3483 * set_current_blocked().
3484 */
3485 tsk->real_blocked = tsk->blocked;
3486 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3487 recalc_sigpending();
3488 spin_unlock_irq(&tsk->sighand->siglock);
3489
3490 __set_current_state(TASK_INTERRUPTIBLE);
3491 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3492 HRTIMER_MODE_REL);
3493 spin_lock_irq(&tsk->sighand->siglock);
3494 __set_task_blocked(tsk, &tsk->real_blocked);
3495 sigemptyset(&tsk->real_blocked);
3496 sig = dequeue_signal(tsk, &mask, info);
3497 }
3498 spin_unlock_irq(&tsk->sighand->siglock);
3499
3500 if (sig)
3501 return sig;
3502 return ret ? -EINTR : -EAGAIN;
3503}
3504
3505/**
3506 * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3507 * in @uthese
3508 * @uthese: queued signals to wait for
3509 * @uinfo: if non-null, the signal's siginfo is returned here
3510 * @uts: upper bound on process time suspension
3511 * @sigsetsize: size of sigset_t type
3512 */
3513SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3514 siginfo_t __user *, uinfo,
3515 const struct __kernel_timespec __user *, uts,
3516 size_t, sigsetsize)
3517{
3518 sigset_t these;
3519 struct timespec64 ts;
3520 kernel_siginfo_t info;
3521 int ret;
3522
3523 /* XXX: Don't preclude handling different sized sigset_t's. */
3524 if (sigsetsize != sizeof(sigset_t))
3525 return -EINVAL;
3526
3527 if (copy_from_user(&these, uthese, sizeof(these)))
3528 return -EFAULT;
3529
3530 if (uts) {
3531 if (get_timespec64(&ts, uts))
3532 return -EFAULT;
3533 }
3534
3535 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3536
3537 if (ret > 0 && uinfo) {
3538 if (copy_siginfo_to_user(uinfo, &info))
3539 ret = -EFAULT;
3540 }
3541
3542 return ret;
3543}
3544
3545#ifdef CONFIG_COMPAT_32BIT_TIME
3546SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3547 siginfo_t __user *, uinfo,
3548 const struct old_timespec32 __user *, uts,
3549 size_t, sigsetsize)
3550{
3551 sigset_t these;
3552 struct timespec64 ts;
3553 kernel_siginfo_t info;
3554 int ret;
3555
3556 if (sigsetsize != sizeof(sigset_t))
3557 return -EINVAL;
3558
3559 if (copy_from_user(&these, uthese, sizeof(these)))
3560 return -EFAULT;
3561
3562 if (uts) {
3563 if (get_old_timespec32(&ts, uts))
3564 return -EFAULT;
3565 }
3566
3567 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3568
3569 if (ret > 0 && uinfo) {
3570 if (copy_siginfo_to_user(uinfo, &info))
3571 ret = -EFAULT;
3572 }
3573
3574 return ret;
3575}
3576#endif
3577
3578#ifdef CONFIG_COMPAT
3579COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3580 struct compat_siginfo __user *, uinfo,
3581 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3582{
3583 sigset_t s;
3584 struct timespec64 t;
3585 kernel_siginfo_t info;
3586 long ret;
3587
3588 if (sigsetsize != sizeof(sigset_t))
3589 return -EINVAL;
3590
3591 if (get_compat_sigset(&s, uthese))
3592 return -EFAULT;
3593
3594 if (uts) {
3595 if (get_timespec64(&t, uts))
3596 return -EFAULT;
3597 }
3598
3599 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3600
3601 if (ret > 0 && uinfo) {
3602 if (copy_siginfo_to_user32(uinfo, &info))
3603 ret = -EFAULT;
3604 }
3605
3606 return ret;
3607}
3608
3609#ifdef CONFIG_COMPAT_32BIT_TIME
3610COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3611 struct compat_siginfo __user *, uinfo,
3612 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3613{
3614 sigset_t s;
3615 struct timespec64 t;
3616 kernel_siginfo_t info;
3617 long ret;
3618
3619 if (sigsetsize != sizeof(sigset_t))
3620 return -EINVAL;
3621
3622 if (get_compat_sigset(&s, uthese))
3623 return -EFAULT;
3624
3625 if (uts) {
3626 if (get_old_timespec32(&t, uts))
3627 return -EFAULT;
3628 }
3629
3630 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3631
3632 if (ret > 0 && uinfo) {
3633 if (copy_siginfo_to_user32(uinfo, &info))
3634 ret = -EFAULT;
3635 }
3636
3637 return ret;
3638}
3639#endif
3640#endif
3641
3642static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3643{
3644 clear_siginfo(info);
3645 info->si_signo = sig;
3646 info->si_errno = 0;
3647 info->si_code = SI_USER;
3648 info->si_pid = task_tgid_vnr(current);
3649 info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3650}
3651
3652/**
3653 * sys_kill - send a signal to a process
3654 * @pid: the PID of the process
3655 * @sig: signal to be sent
3656 */
3657SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3658{
3659 struct kernel_siginfo info;
3660
3661 prepare_kill_siginfo(sig, &info);
3662
3663 return kill_something_info(sig, &info, pid);
3664}
3665
3666/*
3667 * Verify that the signaler and signalee either are in the same pid namespace
3668 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3669 * namespace.
3670 */
3671static bool access_pidfd_pidns(struct pid *pid)
3672{
3673 struct pid_namespace *active = task_active_pid_ns(current);
3674 struct pid_namespace *p = ns_of_pid(pid);
3675
3676 for (;;) {
3677 if (!p)
3678 return false;
3679 if (p == active)
3680 break;
3681 p = p->parent;
3682 }
3683
3684 return true;
3685}
3686
3687static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo, siginfo_t *info)
3688{
3689#ifdef CONFIG_COMPAT
3690 /*
3691 * Avoid hooking up compat syscalls and instead handle necessary
3692 * conversions here. Note, this is a stop-gap measure and should not be
3693 * considered a generic solution.
3694 */
3695 if (in_compat_syscall())
3696 return copy_siginfo_from_user32(
3697 kinfo, (struct compat_siginfo __user *)info);
3698#endif
3699 return copy_siginfo_from_user(kinfo, info);
3700}
3701
3702static struct pid *pidfd_to_pid(const struct file *file)
3703{
3704 struct pid *pid;
3705
3706 pid = pidfd_pid(file);
3707 if (!IS_ERR(pid))
3708 return pid;
3709
3710 return tgid_pidfd_to_pid(file);
3711}
3712
3713/**
3714 * sys_pidfd_send_signal - Signal a process through a pidfd
3715 * @pidfd: file descriptor of the process
3716 * @sig: signal to send
3717 * @info: signal info
3718 * @flags: future flags
3719 *
3720 * The syscall currently only signals via PIDTYPE_PID which covers
3721 * kill(<positive-pid>, <signal>. It does not signal threads or process
3722 * groups.
3723 * In order to extend the syscall to threads and process groups the @flags
3724 * argument should be used. In essence, the @flags argument will determine
3725 * what is signaled and not the file descriptor itself. Put in other words,
3726 * grouping is a property of the flags argument not a property of the file
3727 * descriptor.
3728 *
3729 * Return: 0 on success, negative errno on failure
3730 */
3731SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3732 siginfo_t __user *, info, unsigned int, flags)
3733{
3734 int ret;
3735 struct fd f;
3736 struct pid *pid;
3737 kernel_siginfo_t kinfo;
3738
3739 /* Enforce flags be set to 0 until we add an extension. */
3740 if (flags)
3741 return -EINVAL;
3742
3743 f = fdget(pidfd);
3744 if (!f.file)
3745 return -EBADF;
3746
3747 /* Is this a pidfd? */
3748 pid = pidfd_to_pid(f.file);
3749 if (IS_ERR(pid)) {
3750 ret = PTR_ERR(pid);
3751 goto err;
3752 }
3753
3754 ret = -EINVAL;
3755 if (!access_pidfd_pidns(pid))
3756 goto err;
3757
3758 if (info) {
3759 ret = copy_siginfo_from_user_any(&kinfo, info);
3760 if (unlikely(ret))
3761 goto err;
3762
3763 ret = -EINVAL;
3764 if (unlikely(sig != kinfo.si_signo))
3765 goto err;
3766
3767 /* Only allow sending arbitrary signals to yourself. */
3768 ret = -EPERM;
3769 if ((task_pid(current) != pid) &&
3770 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3771 goto err;
3772 } else {
3773 prepare_kill_siginfo(sig, &kinfo);
3774 }
3775
3776 ret = kill_pid_info(sig, &kinfo, pid);
3777
3778err:
3779 fdput(f);
3780 return ret;
3781}
3782
3783static int
3784do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3785{
3786 struct task_struct *p;
3787 int error = -ESRCH;
3788
3789 rcu_read_lock();
3790 p = find_task_by_vpid(pid);
3791 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3792 error = check_kill_permission(sig, info, p);
3793 /*
3794 * The null signal is a permissions and process existence
3795 * probe. No signal is actually delivered.
3796 */
3797 if (!error && sig) {
3798 error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3799 /*
3800 * If lock_task_sighand() failed we pretend the task
3801 * dies after receiving the signal. The window is tiny,
3802 * and the signal is private anyway.
3803 */
3804 if (unlikely(error == -ESRCH))
3805 error = 0;
3806 }
3807 }
3808 rcu_read_unlock();
3809
3810 return error;
3811}
3812
3813static int do_tkill(pid_t tgid, pid_t pid, int sig)
3814{
3815 struct kernel_siginfo info;
3816
3817 clear_siginfo(&info);
3818 info.si_signo = sig;
3819 info.si_errno = 0;
3820 info.si_code = SI_TKILL;
3821 info.si_pid = task_tgid_vnr(current);
3822 info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3823
3824 return do_send_specific(tgid, pid, sig, &info);
3825}
3826
3827/**
3828 * sys_tgkill - send signal to one specific thread
3829 * @tgid: the thread group ID of the thread
3830 * @pid: the PID of the thread
3831 * @sig: signal to be sent
3832 *
3833 * This syscall also checks the @tgid and returns -ESRCH even if the PID
3834 * exists but it's not belonging to the target process anymore. This
3835 * method solves the problem of threads exiting and PIDs getting reused.
3836 */
3837SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3838{
3839 /* This is only valid for single tasks */
3840 if (pid <= 0 || tgid <= 0)
3841 return -EINVAL;
3842
3843 return do_tkill(tgid, pid, sig);
3844}
3845
3846/**
3847 * sys_tkill - send signal to one specific task
3848 * @pid: the PID of the task
3849 * @sig: signal to be sent
3850 *
3851 * Send a signal to only one task, even if it's a CLONE_THREAD task.
3852 */
3853SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3854{
3855 /* This is only valid for single tasks */
3856 if (pid <= 0)
3857 return -EINVAL;
3858
3859 return do_tkill(0, pid, sig);
3860}
3861
3862static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3863{
3864 /* Not even root can pretend to send signals from the kernel.
3865 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3866 */
3867 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3868 (task_pid_vnr(current) != pid))
3869 return -EPERM;
3870
3871 /* POSIX.1b doesn't mention process groups. */
3872 return kill_proc_info(sig, info, pid);
3873}
3874
3875/**
3876 * sys_rt_sigqueueinfo - send signal information to a signal
3877 * @pid: the PID of the thread
3878 * @sig: signal to be sent
3879 * @uinfo: signal info to be sent
3880 */
3881SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3882 siginfo_t __user *, uinfo)
3883{
3884 kernel_siginfo_t info;
3885 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3886 if (unlikely(ret))
3887 return ret;
3888 return do_rt_sigqueueinfo(pid, sig, &info);
3889}
3890
3891#ifdef CONFIG_COMPAT
3892COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3893 compat_pid_t, pid,
3894 int, sig,
3895 struct compat_siginfo __user *, uinfo)
3896{
3897 kernel_siginfo_t info;
3898 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3899 if (unlikely(ret))
3900 return ret;
3901 return do_rt_sigqueueinfo(pid, sig, &info);
3902}
3903#endif
3904
3905static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
3906{
3907 /* This is only valid for single tasks */
3908 if (pid <= 0 || tgid <= 0)
3909 return -EINVAL;
3910
3911 /* Not even root can pretend to send signals from the kernel.
3912 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3913 */
3914 if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3915 (task_pid_vnr(current) != pid))
3916 return -EPERM;
3917
3918 return do_send_specific(tgid, pid, sig, info);
3919}
3920
3921SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3922 siginfo_t __user *, uinfo)
3923{
3924 kernel_siginfo_t info;
3925 int ret = __copy_siginfo_from_user(sig, &info, uinfo);
3926 if (unlikely(ret))
3927 return ret;
3928 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3929}
3930
3931#ifdef CONFIG_COMPAT
3932COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3933 compat_pid_t, tgid,
3934 compat_pid_t, pid,
3935 int, sig,
3936 struct compat_siginfo __user *, uinfo)
3937{
3938 kernel_siginfo_t info;
3939 int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
3940 if (unlikely(ret))
3941 return ret;
3942 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3943}
3944#endif
3945
3946/*
3947 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3948 */
3949void kernel_sigaction(int sig, __sighandler_t action)
3950{
3951 spin_lock_irq(¤t->sighand->siglock);
3952 current->sighand->action[sig - 1].sa.sa_handler = action;
3953 if (action == SIG_IGN) {
3954 sigset_t mask;
3955
3956 sigemptyset(&mask);
3957 sigaddset(&mask, sig);
3958
3959 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
3960 flush_sigqueue_mask(&mask, ¤t->pending);
3961 recalc_sigpending();
3962 }
3963 spin_unlock_irq(¤t->sighand->siglock);
3964}
3965EXPORT_SYMBOL(kernel_sigaction);
3966
3967void __weak sigaction_compat_abi(struct k_sigaction *act,
3968 struct k_sigaction *oact)
3969{
3970}
3971
3972int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3973{
3974 struct task_struct *p = current, *t;
3975 struct k_sigaction *k;
3976 sigset_t mask;
3977
3978 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3979 return -EINVAL;
3980
3981 k = &p->sighand->action[sig-1];
3982
3983 spin_lock_irq(&p->sighand->siglock);
3984 if (oact)
3985 *oact = *k;
3986
3987 sigaction_compat_abi(act, oact);
3988
3989 if (act) {
3990 sigdelsetmask(&act->sa.sa_mask,
3991 sigmask(SIGKILL) | sigmask(SIGSTOP));
3992 *k = *act;
3993 /*
3994 * POSIX 3.3.1.3:
3995 * "Setting a signal action to SIG_IGN for a signal that is
3996 * pending shall cause the pending signal to be discarded,
3997 * whether or not it is blocked."
3998 *
3999 * "Setting a signal action to SIG_DFL for a signal that is
4000 * pending and whose default action is to ignore the signal
4001 * (for example, SIGCHLD), shall cause the pending signal to
4002 * be discarded, whether or not it is blocked"
4003 */
4004 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4005 sigemptyset(&mask);
4006 sigaddset(&mask, sig);
4007 flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4008 for_each_thread(p, t)
4009 flush_sigqueue_mask(&mask, &t->pending);
4010 }
4011 }
4012
4013 spin_unlock_irq(&p->sighand->siglock);
4014 return 0;
4015}
4016
4017static int
4018do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4019 size_t min_ss_size)
4020{
4021 struct task_struct *t = current;
4022
4023 if (oss) {
4024 memset(oss, 0, sizeof(stack_t));
4025 oss->ss_sp = (void __user *) t->sas_ss_sp;
4026 oss->ss_size = t->sas_ss_size;
4027 oss->ss_flags = sas_ss_flags(sp) |
4028 (current->sas_ss_flags & SS_FLAG_BITS);
4029 }
4030
4031 if (ss) {
4032 void __user *ss_sp = ss->ss_sp;
4033 size_t ss_size = ss->ss_size;
4034 unsigned ss_flags = ss->ss_flags;
4035 int ss_mode;
4036
4037 if (unlikely(on_sig_stack(sp)))
4038 return -EPERM;
4039
4040 ss_mode = ss_flags & ~SS_FLAG_BITS;
4041 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4042 ss_mode != 0))
4043 return -EINVAL;
4044
4045 if (ss_mode == SS_DISABLE) {
4046 ss_size = 0;
4047 ss_sp = NULL;
4048 } else {
4049 if (unlikely(ss_size < min_ss_size))
4050 return -ENOMEM;
4051 }
4052
4053 t->sas_ss_sp = (unsigned long) ss_sp;
4054 t->sas_ss_size = ss_size;
4055 t->sas_ss_flags = ss_flags;
4056 }
4057 return 0;
4058}
4059
4060SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4061{
4062 stack_t new, old;
4063 int err;
4064 if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4065 return -EFAULT;
4066 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4067 current_user_stack_pointer(),
4068 MINSIGSTKSZ);
4069 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4070 err = -EFAULT;
4071 return err;
4072}
4073
4074int restore_altstack(const stack_t __user *uss)
4075{
4076 stack_t new;
4077 if (copy_from_user(&new, uss, sizeof(stack_t)))
4078 return -EFAULT;
4079 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4080 MINSIGSTKSZ);
4081 /* squash all but EFAULT for now */
4082 return 0;
4083}
4084
4085int __save_altstack(stack_t __user *uss, unsigned long sp)
4086{
4087 struct task_struct *t = current;
4088 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4089 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4090 __put_user(t->sas_ss_size, &uss->ss_size);
4091 if (err)
4092 return err;
4093 if (t->sas_ss_flags & SS_AUTODISARM)
4094 sas_ss_reset(t);
4095 return 0;
4096}
4097
4098#ifdef CONFIG_COMPAT
4099static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4100 compat_stack_t __user *uoss_ptr)
4101{
4102 stack_t uss, uoss;
4103 int ret;
4104
4105 if (uss_ptr) {
4106 compat_stack_t uss32;
4107 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4108 return -EFAULT;
4109 uss.ss_sp = compat_ptr(uss32.ss_sp);
4110 uss.ss_flags = uss32.ss_flags;
4111 uss.ss_size = uss32.ss_size;
4112 }
4113 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4114 compat_user_stack_pointer(),
4115 COMPAT_MINSIGSTKSZ);
4116 if (ret >= 0 && uoss_ptr) {
4117 compat_stack_t old;
4118 memset(&old, 0, sizeof(old));
4119 old.ss_sp = ptr_to_compat(uoss.ss_sp);
4120 old.ss_flags = uoss.ss_flags;
4121 old.ss_size = uoss.ss_size;
4122 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4123 ret = -EFAULT;
4124 }
4125 return ret;
4126}
4127
4128COMPAT_SYSCALL_DEFINE2(sigaltstack,
4129 const compat_stack_t __user *, uss_ptr,
4130 compat_stack_t __user *, uoss_ptr)
4131{
4132 return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4133}
4134
4135int compat_restore_altstack(const compat_stack_t __user *uss)
4136{
4137 int err = do_compat_sigaltstack(uss, NULL);
4138 /* squash all but -EFAULT for now */
4139 return err == -EFAULT ? err : 0;
4140}
4141
4142int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4143{
4144 int err;
4145 struct task_struct *t = current;
4146 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4147 &uss->ss_sp) |
4148 __put_user(t->sas_ss_flags, &uss->ss_flags) |
4149 __put_user(t->sas_ss_size, &uss->ss_size);
4150 if (err)
4151 return err;
4152 if (t->sas_ss_flags & SS_AUTODISARM)
4153 sas_ss_reset(t);
4154 return 0;
4155}
4156#endif
4157
4158#ifdef __ARCH_WANT_SYS_SIGPENDING
4159
4160/**
4161 * sys_sigpending - examine pending signals
4162 * @uset: where mask of pending signal is returned
4163 */
4164SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4165{
4166 sigset_t set;
4167
4168 if (sizeof(old_sigset_t) > sizeof(*uset))
4169 return -EINVAL;
4170
4171 do_sigpending(&set);
4172
4173 if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4174 return -EFAULT;
4175
4176 return 0;
4177}
4178
4179#ifdef CONFIG_COMPAT
4180COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4181{
4182 sigset_t set;
4183
4184 do_sigpending(&set);
4185
4186 return put_user(set.sig[0], set32);
4187}
4188#endif
4189
4190#endif
4191
4192#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4193/**
4194 * sys_sigprocmask - examine and change blocked signals
4195 * @how: whether to add, remove, or set signals
4196 * @nset: signals to add or remove (if non-null)
4197 * @oset: previous value of signal mask if non-null
4198 *
4199 * Some platforms have their own version with special arguments;
4200 * others support only sys_rt_sigprocmask.
4201 */
4202
4203SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4204 old_sigset_t __user *, oset)
4205{
4206 old_sigset_t old_set, new_set;
4207 sigset_t new_blocked;
4208
4209 old_set = current->blocked.sig[0];
4210
4211 if (nset) {
4212 if (copy_from_user(&new_set, nset, sizeof(*nset)))
4213 return -EFAULT;
4214
4215 new_blocked = current->blocked;
4216
4217 switch (how) {
4218 case SIG_BLOCK:
4219 sigaddsetmask(&new_blocked, new_set);
4220 break;
4221 case SIG_UNBLOCK:
4222 sigdelsetmask(&new_blocked, new_set);
4223 break;
4224 case SIG_SETMASK:
4225 new_blocked.sig[0] = new_set;
4226 break;
4227 default:
4228 return -EINVAL;
4229 }
4230
4231 set_current_blocked(&new_blocked);
4232 }
4233
4234 if (oset) {
4235 if (copy_to_user(oset, &old_set, sizeof(*oset)))
4236 return -EFAULT;
4237 }
4238
4239 return 0;
4240}
4241#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4242
4243#ifndef CONFIG_ODD_RT_SIGACTION
4244/**
4245 * sys_rt_sigaction - alter an action taken by a process
4246 * @sig: signal to be sent
4247 * @act: new sigaction
4248 * @oact: used to save the previous sigaction
4249 * @sigsetsize: size of sigset_t type
4250 */
4251SYSCALL_DEFINE4(rt_sigaction, int, sig,
4252 const struct sigaction __user *, act,
4253 struct sigaction __user *, oact,
4254 size_t, sigsetsize)
4255{
4256 struct k_sigaction new_sa, old_sa;
4257 int ret;
4258
4259 /* XXX: Don't preclude handling different sized sigset_t's. */
4260 if (sigsetsize != sizeof(sigset_t))
4261 return -EINVAL;
4262
4263 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4264 return -EFAULT;
4265
4266 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4267 if (ret)
4268 return ret;
4269
4270 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4271 return -EFAULT;
4272
4273 return 0;
4274}
4275#ifdef CONFIG_COMPAT
4276COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4277 const struct compat_sigaction __user *, act,
4278 struct compat_sigaction __user *, oact,
4279 compat_size_t, sigsetsize)
4280{
4281 struct k_sigaction new_ka, old_ka;
4282#ifdef __ARCH_HAS_SA_RESTORER
4283 compat_uptr_t restorer;
4284#endif
4285 int ret;
4286
4287 /* XXX: Don't preclude handling different sized sigset_t's. */
4288 if (sigsetsize != sizeof(compat_sigset_t))
4289 return -EINVAL;
4290
4291 if (act) {
4292 compat_uptr_t handler;
4293 ret = get_user(handler, &act->sa_handler);
4294 new_ka.sa.sa_handler = compat_ptr(handler);
4295#ifdef __ARCH_HAS_SA_RESTORER
4296 ret |= get_user(restorer, &act->sa_restorer);
4297 new_ka.sa.sa_restorer = compat_ptr(restorer);
4298#endif
4299 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4300 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4301 if (ret)
4302 return -EFAULT;
4303 }
4304
4305 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4306 if (!ret && oact) {
4307 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4308 &oact->sa_handler);
4309 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4310 sizeof(oact->sa_mask));
4311 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4312#ifdef __ARCH_HAS_SA_RESTORER
4313 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4314 &oact->sa_restorer);
4315#endif
4316 }
4317 return ret;
4318}
4319#endif
4320#endif /* !CONFIG_ODD_RT_SIGACTION */
4321
4322#ifdef CONFIG_OLD_SIGACTION
4323SYSCALL_DEFINE3(sigaction, int, sig,
4324 const struct old_sigaction __user *, act,
4325 struct old_sigaction __user *, oact)
4326{
4327 struct k_sigaction new_ka, old_ka;
4328 int ret;
4329
4330 if (act) {
4331 old_sigset_t mask;
4332 if (!access_ok(act, sizeof(*act)) ||
4333 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4334 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4335 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4336 __get_user(mask, &act->sa_mask))
4337 return -EFAULT;
4338#ifdef __ARCH_HAS_KA_RESTORER
4339 new_ka.ka_restorer = NULL;
4340#endif
4341 siginitset(&new_ka.sa.sa_mask, mask);
4342 }
4343
4344 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4345
4346 if (!ret && oact) {
4347 if (!access_ok(oact, sizeof(*oact)) ||
4348 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4349 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4350 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4351 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4352 return -EFAULT;
4353 }
4354
4355 return ret;
4356}
4357#endif
4358#ifdef CONFIG_COMPAT_OLD_SIGACTION
4359COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4360 const struct compat_old_sigaction __user *, act,
4361 struct compat_old_sigaction __user *, oact)
4362{
4363 struct k_sigaction new_ka, old_ka;
4364 int ret;
4365 compat_old_sigset_t mask;
4366 compat_uptr_t handler, restorer;
4367
4368 if (act) {
4369 if (!access_ok(act, sizeof(*act)) ||
4370 __get_user(handler, &act->sa_handler) ||
4371 __get_user(restorer, &act->sa_restorer) ||
4372 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4373 __get_user(mask, &act->sa_mask))
4374 return -EFAULT;
4375
4376#ifdef __ARCH_HAS_KA_RESTORER
4377 new_ka.ka_restorer = NULL;
4378#endif
4379 new_ka.sa.sa_handler = compat_ptr(handler);
4380 new_ka.sa.sa_restorer = compat_ptr(restorer);
4381 siginitset(&new_ka.sa.sa_mask, mask);
4382 }
4383
4384 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4385
4386 if (!ret && oact) {
4387 if (!access_ok(oact, sizeof(*oact)) ||
4388 __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4389 &oact->sa_handler) ||
4390 __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4391 &oact->sa_restorer) ||
4392 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4393 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4394 return -EFAULT;
4395 }
4396 return ret;
4397}
4398#endif
4399
4400#ifdef CONFIG_SGETMASK_SYSCALL
4401
4402/*
4403 * For backwards compatibility. Functionality superseded by sigprocmask.
4404 */
4405SYSCALL_DEFINE0(sgetmask)
4406{
4407 /* SMP safe */
4408 return current->blocked.sig[0];
4409}
4410
4411SYSCALL_DEFINE1(ssetmask, int, newmask)
4412{
4413 int old = current->blocked.sig[0];
4414 sigset_t newset;
4415
4416 siginitset(&newset, newmask);
4417 set_current_blocked(&newset);
4418
4419 return old;
4420}
4421#endif /* CONFIG_SGETMASK_SYSCALL */
4422
4423#ifdef __ARCH_WANT_SYS_SIGNAL
4424/*
4425 * For backwards compatibility. Functionality superseded by sigaction.
4426 */
4427SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4428{
4429 struct k_sigaction new_sa, old_sa;
4430 int ret;
4431
4432 new_sa.sa.sa_handler = handler;
4433 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4434 sigemptyset(&new_sa.sa.sa_mask);
4435
4436 ret = do_sigaction(sig, &new_sa, &old_sa);
4437
4438 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4439}
4440#endif /* __ARCH_WANT_SYS_SIGNAL */
4441
4442#ifdef __ARCH_WANT_SYS_PAUSE
4443
4444SYSCALL_DEFINE0(pause)
4445{
4446 while (!signal_pending(current)) {
4447 __set_current_state(TASK_INTERRUPTIBLE);
4448 schedule();
4449 }
4450 return -ERESTARTNOHAND;
4451}
4452
4453#endif
4454
4455static int sigsuspend(sigset_t *set)
4456{
4457 current->saved_sigmask = current->blocked;
4458 set_current_blocked(set);
4459
4460 while (!signal_pending(current)) {
4461 __set_current_state(TASK_INTERRUPTIBLE);
4462 schedule();
4463 }
4464 set_restore_sigmask();
4465 return -ERESTARTNOHAND;
4466}
4467
4468/**
4469 * sys_rt_sigsuspend - replace the signal mask for a value with the
4470 * @unewset value until a signal is received
4471 * @unewset: new signal mask value
4472 * @sigsetsize: size of sigset_t type
4473 */
4474SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4475{
4476 sigset_t newset;
4477
4478 /* XXX: Don't preclude handling different sized sigset_t's. */
4479 if (sigsetsize != sizeof(sigset_t))
4480 return -EINVAL;
4481
4482 if (copy_from_user(&newset, unewset, sizeof(newset)))
4483 return -EFAULT;
4484 return sigsuspend(&newset);
4485}
4486
4487#ifdef CONFIG_COMPAT
4488COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4489{
4490 sigset_t newset;
4491
4492 /* XXX: Don't preclude handling different sized sigset_t's. */
4493 if (sigsetsize != sizeof(sigset_t))
4494 return -EINVAL;
4495
4496 if (get_compat_sigset(&newset, unewset))
4497 return -EFAULT;
4498 return sigsuspend(&newset);
4499}
4500#endif
4501
4502#ifdef CONFIG_OLD_SIGSUSPEND
4503SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4504{
4505 sigset_t blocked;
4506 siginitset(&blocked, mask);
4507 return sigsuspend(&blocked);
4508}
4509#endif
4510#ifdef CONFIG_OLD_SIGSUSPEND3
4511SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4512{
4513 sigset_t blocked;
4514 siginitset(&blocked, mask);
4515 return sigsuspend(&blocked);
4516}
4517#endif
4518
4519__weak const char *arch_vma_name(struct vm_area_struct *vma)
4520{
4521 return NULL;
4522}
4523
4524static inline void siginfo_buildtime_checks(void)
4525{
4526 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4527
4528 /* Verify the offsets in the two siginfos match */
4529#define CHECK_OFFSET(field) \
4530 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4531
4532 /* kill */
4533 CHECK_OFFSET(si_pid);
4534 CHECK_OFFSET(si_uid);
4535
4536 /* timer */
4537 CHECK_OFFSET(si_tid);
4538 CHECK_OFFSET(si_overrun);
4539 CHECK_OFFSET(si_value);
4540
4541 /* rt */
4542 CHECK_OFFSET(si_pid);
4543 CHECK_OFFSET(si_uid);
4544 CHECK_OFFSET(si_value);
4545
4546 /* sigchld */
4547 CHECK_OFFSET(si_pid);
4548 CHECK_OFFSET(si_uid);
4549 CHECK_OFFSET(si_status);
4550 CHECK_OFFSET(si_utime);
4551 CHECK_OFFSET(si_stime);
4552
4553 /* sigfault */
4554 CHECK_OFFSET(si_addr);
4555 CHECK_OFFSET(si_addr_lsb);
4556 CHECK_OFFSET(si_lower);
4557 CHECK_OFFSET(si_upper);
4558 CHECK_OFFSET(si_pkey);
4559
4560 /* sigpoll */
4561 CHECK_OFFSET(si_band);
4562 CHECK_OFFSET(si_fd);
4563
4564 /* sigsys */
4565 CHECK_OFFSET(si_call_addr);
4566 CHECK_OFFSET(si_syscall);
4567 CHECK_OFFSET(si_arch);
4568#undef CHECK_OFFSET
4569
4570 /* usb asyncio */
4571 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4572 offsetof(struct siginfo, si_addr));
4573 if (sizeof(int) == sizeof(void __user *)) {
4574 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4575 sizeof(void __user *));
4576 } else {
4577 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4578 sizeof_field(struct siginfo, si_uid)) !=
4579 sizeof(void __user *));
4580 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4581 offsetof(struct siginfo, si_uid));
4582 }
4583#ifdef CONFIG_COMPAT
4584 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4585 offsetof(struct compat_siginfo, si_addr));
4586 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4587 sizeof(compat_uptr_t));
4588 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4589 sizeof_field(struct siginfo, si_pid));
4590#endif
4591}
4592
4593void __init signals_init(void)
4594{
4595 siginfo_buildtime_checks();
4596
4597 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4598}
4599
4600#ifdef CONFIG_KGDB_KDB
4601#include <linux/kdb.h>
4602/*
4603 * kdb_send_sig - Allows kdb to send signals without exposing
4604 * signal internals. This function checks if the required locks are
4605 * available before calling the main signal code, to avoid kdb
4606 * deadlocks.
4607 */
4608void kdb_send_sig(struct task_struct *t, int sig)
4609{
4610 static struct task_struct *kdb_prev_t;
4611 int new_t, ret;
4612 if (!spin_trylock(&t->sighand->siglock)) {
4613 kdb_printf("Can't do kill command now.\n"
4614 "The sigmask lock is held somewhere else in "
4615 "kernel, try again later\n");
4616 return;
4617 }
4618 new_t = kdb_prev_t != t;
4619 kdb_prev_t = t;
4620 if (t->state != TASK_RUNNING && new_t) {
4621 spin_unlock(&t->sighand->siglock);
4622 kdb_printf("Process is not RUNNING, sending a signal from "
4623 "kdb risks deadlock\n"
4624 "on the run queue locks. "
4625 "The signal has _not_ been sent.\n"
4626 "Reissue the kill command if you want to risk "
4627 "the deadlock.\n");
4628 return;
4629 }
4630 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4631 spin_unlock(&t->sighand->siglock);
4632 if (ret)
4633 kdb_printf("Fail to deliver Signal %d to process %d.\n",
4634 sig, t->pid);
4635 else
4636 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4637}
4638#endif /* CONFIG_KGDB_KDB */