xref: /linux/kernel/signal.c (revision af50e4ba34f4c45e92535364133d4deb5931c1c5)
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/mm.h>
17 #include <linux/sched/user.h>
18 #include <linux/sched/debug.h>
19 #include <linux/sched/task.h>
20 #include <linux/sched/task_stack.h>
21 #include <linux/sched/cputime.h>
22 #include <linux/fs.h>
23 #include <linux/tty.h>
24 #include <linux/binfmts.h>
25 #include <linux/coredump.h>
26 #include <linux/security.h>
27 #include <linux/syscalls.h>
28 #include <linux/ptrace.h>
29 #include <linux/signal.h>
30 #include <linux/signalfd.h>
31 #include <linux/ratelimit.h>
32 #include <linux/tracehook.h>
33 #include <linux/capability.h>
34 #include <linux/freezer.h>
35 #include <linux/pid_namespace.h>
36 #include <linux/nsproxy.h>
37 #include <linux/user_namespace.h>
38 #include <linux/uprobes.h>
39 #include <linux/compat.h>
40 #include <linux/cn_proc.h>
41 #include <linux/compiler.h>
42 #include <linux/posix-timers.h>
43 #include <linux/livepatch.h>
44 
45 #define CREATE_TRACE_POINTS
46 #include <trace/events/signal.h>
47 
48 #include <asm/param.h>
49 #include <linux/uaccess.h>
50 #include <asm/unistd.h>
51 #include <asm/siginfo.h>
52 #include <asm/cacheflush.h>
53 #include "audit.h"	/* audit_signal_info() */
54 
55 /*
56  * SLAB caches for signal bits.
57  */
58 
59 static struct kmem_cache *sigqueue_cachep;
60 
61 int print_fatal_signals __read_mostly;
62 
63 static void __user *sig_handler(struct task_struct *t, int sig)
64 {
65 	return t->sighand->action[sig - 1].sa.sa_handler;
66 }
67 
68 static int sig_handler_ignored(void __user *handler, int sig)
69 {
70 	/* Is it explicitly or implicitly ignored? */
71 	return handler == SIG_IGN ||
72 		(handler == SIG_DFL && sig_kernel_ignore(sig));
73 }
74 
75 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
76 {
77 	void __user *handler;
78 
79 	handler = sig_handler(t, sig);
80 
81 	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
82 	    handler == SIG_DFL && !(force && sig_kernel_only(sig)))
83 		return 1;
84 
85 	return sig_handler_ignored(handler, sig);
86 }
87 
88 static int sig_ignored(struct task_struct *t, int sig, bool force)
89 {
90 	/*
91 	 * Blocked signals are never ignored, since the
92 	 * signal handler may change by the time it is
93 	 * unblocked.
94 	 */
95 	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
96 		return 0;
97 
98 	/*
99 	 * Tracers may want to know about even ignored signal unless it
100 	 * is SIGKILL which can't be reported anyway but can be ignored
101 	 * by SIGNAL_UNKILLABLE task.
102 	 */
103 	if (t->ptrace && sig != SIGKILL)
104 		return 0;
105 
106 	return sig_task_ignored(t, sig, force);
107 }
108 
109 /*
110  * Re-calculate pending state from the set of locally pending
111  * signals, globally pending signals, and blocked signals.
112  */
113 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
114 {
115 	unsigned long ready;
116 	long i;
117 
118 	switch (_NSIG_WORDS) {
119 	default:
120 		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
121 			ready |= signal->sig[i] &~ blocked->sig[i];
122 		break;
123 
124 	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
125 		ready |= signal->sig[2] &~ blocked->sig[2];
126 		ready |= signal->sig[1] &~ blocked->sig[1];
127 		ready |= signal->sig[0] &~ blocked->sig[0];
128 		break;
129 
130 	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
131 		ready |= signal->sig[0] &~ blocked->sig[0];
132 		break;
133 
134 	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
135 	}
136 	return ready !=	0;
137 }
138 
139 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
140 
141 static int recalc_sigpending_tsk(struct task_struct *t)
142 {
143 	if ((t->jobctl & JOBCTL_PENDING_MASK) ||
144 	    PENDING(&t->pending, &t->blocked) ||
145 	    PENDING(&t->signal->shared_pending, &t->blocked)) {
146 		set_tsk_thread_flag(t, TIF_SIGPENDING);
147 		return 1;
148 	}
149 	/*
150 	 * We must never clear the flag in another thread, or in current
151 	 * when it's possible the current syscall is returning -ERESTART*.
152 	 * So we don't clear it here, and only callers who know they should do.
153 	 */
154 	return 0;
155 }
156 
157 /*
158  * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
159  * This is superfluous when called on current, the wakeup is a harmless no-op.
160  */
161 void recalc_sigpending_and_wake(struct task_struct *t)
162 {
163 	if (recalc_sigpending_tsk(t))
164 		signal_wake_up(t, 0);
165 }
166 
167 void recalc_sigpending(void)
168 {
169 	if (!recalc_sigpending_tsk(current) && !freezing(current) &&
170 	    !klp_patch_pending(current))
171 		clear_thread_flag(TIF_SIGPENDING);
172 
173 }
174 
175 /* Given the mask, find the first available signal that should be serviced. */
176 
177 #define SYNCHRONOUS_MASK \
178 	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
179 	 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
180 
181 int next_signal(struct sigpending *pending, sigset_t *mask)
182 {
183 	unsigned long i, *s, *m, x;
184 	int sig = 0;
185 
186 	s = pending->signal.sig;
187 	m = mask->sig;
188 
189 	/*
190 	 * Handle the first word specially: it contains the
191 	 * synchronous signals that need to be dequeued first.
192 	 */
193 	x = *s &~ *m;
194 	if (x) {
195 		if (x & SYNCHRONOUS_MASK)
196 			x &= SYNCHRONOUS_MASK;
197 		sig = ffz(~x) + 1;
198 		return sig;
199 	}
200 
201 	switch (_NSIG_WORDS) {
202 	default:
203 		for (i = 1; i < _NSIG_WORDS; ++i) {
204 			x = *++s &~ *++m;
205 			if (!x)
206 				continue;
207 			sig = ffz(~x) + i*_NSIG_BPW + 1;
208 			break;
209 		}
210 		break;
211 
212 	case 2:
213 		x = s[1] &~ m[1];
214 		if (!x)
215 			break;
216 		sig = ffz(~x) + _NSIG_BPW + 1;
217 		break;
218 
219 	case 1:
220 		/* Nothing to do */
221 		break;
222 	}
223 
224 	return sig;
225 }
226 
227 static inline void print_dropped_signal(int sig)
228 {
229 	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
230 
231 	if (!print_fatal_signals)
232 		return;
233 
234 	if (!__ratelimit(&ratelimit_state))
235 		return;
236 
237 	pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
238 				current->comm, current->pid, sig);
239 }
240 
241 /**
242  * task_set_jobctl_pending - set jobctl pending bits
243  * @task: target task
244  * @mask: pending bits to set
245  *
246  * Clear @mask from @task->jobctl.  @mask must be subset of
247  * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
248  * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
249  * cleared.  If @task is already being killed or exiting, this function
250  * becomes noop.
251  *
252  * CONTEXT:
253  * Must be called with @task->sighand->siglock held.
254  *
255  * RETURNS:
256  * %true if @mask is set, %false if made noop because @task was dying.
257  */
258 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
259 {
260 	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
261 			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
262 	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
263 
264 	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
265 		return false;
266 
267 	if (mask & JOBCTL_STOP_SIGMASK)
268 		task->jobctl &= ~JOBCTL_STOP_SIGMASK;
269 
270 	task->jobctl |= mask;
271 	return true;
272 }
273 
274 /**
275  * task_clear_jobctl_trapping - clear jobctl trapping bit
276  * @task: target task
277  *
278  * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
279  * Clear it and wake up the ptracer.  Note that we don't need any further
280  * locking.  @task->siglock guarantees that @task->parent points to the
281  * ptracer.
282  *
283  * CONTEXT:
284  * Must be called with @task->sighand->siglock held.
285  */
286 void task_clear_jobctl_trapping(struct task_struct *task)
287 {
288 	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
289 		task->jobctl &= ~JOBCTL_TRAPPING;
290 		smp_mb();	/* advised by wake_up_bit() */
291 		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
292 	}
293 }
294 
295 /**
296  * task_clear_jobctl_pending - clear jobctl pending bits
297  * @task: target task
298  * @mask: pending bits to clear
299  *
300  * Clear @mask from @task->jobctl.  @mask must be subset of
301  * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
302  * STOP bits are cleared together.
303  *
304  * If clearing of @mask leaves no stop or trap pending, this function calls
305  * task_clear_jobctl_trapping().
306  *
307  * CONTEXT:
308  * Must be called with @task->sighand->siglock held.
309  */
310 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
311 {
312 	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
313 
314 	if (mask & JOBCTL_STOP_PENDING)
315 		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
316 
317 	task->jobctl &= ~mask;
318 
319 	if (!(task->jobctl & JOBCTL_PENDING_MASK))
320 		task_clear_jobctl_trapping(task);
321 }
322 
323 /**
324  * task_participate_group_stop - participate in a group stop
325  * @task: task participating in a group stop
326  *
327  * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
328  * Group stop states are cleared and the group stop count is consumed if
329  * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
330  * stop, the appropriate %SIGNAL_* flags are set.
331  *
332  * CONTEXT:
333  * Must be called with @task->sighand->siglock held.
334  *
335  * RETURNS:
336  * %true if group stop completion should be notified to the parent, %false
337  * otherwise.
338  */
339 static bool task_participate_group_stop(struct task_struct *task)
340 {
341 	struct signal_struct *sig = task->signal;
342 	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
343 
344 	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
345 
346 	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
347 
348 	if (!consume)
349 		return false;
350 
351 	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
352 		sig->group_stop_count--;
353 
354 	/*
355 	 * Tell the caller to notify completion iff we are entering into a
356 	 * fresh group stop.  Read comment in do_signal_stop() for details.
357 	 */
358 	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
359 		signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
360 		return true;
361 	}
362 	return false;
363 }
364 
365 /*
366  * allocate a new signal queue record
367  * - this may be called without locks if and only if t == current, otherwise an
368  *   appropriate lock must be held to stop the target task from exiting
369  */
370 static struct sigqueue *
371 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
372 {
373 	struct sigqueue *q = NULL;
374 	struct user_struct *user;
375 
376 	/*
377 	 * Protect access to @t credentials. This can go away when all
378 	 * callers hold rcu read lock.
379 	 */
380 	rcu_read_lock();
381 	user = get_uid(__task_cred(t)->user);
382 	atomic_inc(&user->sigpending);
383 	rcu_read_unlock();
384 
385 	if (override_rlimit ||
386 	    atomic_read(&user->sigpending) <=
387 			task_rlimit(t, RLIMIT_SIGPENDING)) {
388 		q = kmem_cache_alloc(sigqueue_cachep, flags);
389 	} else {
390 		print_dropped_signal(sig);
391 	}
392 
393 	if (unlikely(q == NULL)) {
394 		atomic_dec(&user->sigpending);
395 		free_uid(user);
396 	} else {
397 		INIT_LIST_HEAD(&q->list);
398 		q->flags = 0;
399 		q->user = user;
400 	}
401 
402 	return q;
403 }
404 
405 static void __sigqueue_free(struct sigqueue *q)
406 {
407 	if (q->flags & SIGQUEUE_PREALLOC)
408 		return;
409 	atomic_dec(&q->user->sigpending);
410 	free_uid(q->user);
411 	kmem_cache_free(sigqueue_cachep, q);
412 }
413 
414 void flush_sigqueue(struct sigpending *queue)
415 {
416 	struct sigqueue *q;
417 
418 	sigemptyset(&queue->signal);
419 	while (!list_empty(&queue->list)) {
420 		q = list_entry(queue->list.next, struct sigqueue , list);
421 		list_del_init(&q->list);
422 		__sigqueue_free(q);
423 	}
424 }
425 
426 /*
427  * Flush all pending signals for this kthread.
428  */
429 void flush_signals(struct task_struct *t)
430 {
431 	unsigned long flags;
432 
433 	spin_lock_irqsave(&t->sighand->siglock, flags);
434 	clear_tsk_thread_flag(t, TIF_SIGPENDING);
435 	flush_sigqueue(&t->pending);
436 	flush_sigqueue(&t->signal->shared_pending);
437 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
438 }
439 
440 #ifdef CONFIG_POSIX_TIMERS
441 static void __flush_itimer_signals(struct sigpending *pending)
442 {
443 	sigset_t signal, retain;
444 	struct sigqueue *q, *n;
445 
446 	signal = pending->signal;
447 	sigemptyset(&retain);
448 
449 	list_for_each_entry_safe(q, n, &pending->list, list) {
450 		int sig = q->info.si_signo;
451 
452 		if (likely(q->info.si_code != SI_TIMER)) {
453 			sigaddset(&retain, sig);
454 		} else {
455 			sigdelset(&signal, sig);
456 			list_del_init(&q->list);
457 			__sigqueue_free(q);
458 		}
459 	}
460 
461 	sigorsets(&pending->signal, &signal, &retain);
462 }
463 
464 void flush_itimer_signals(void)
465 {
466 	struct task_struct *tsk = current;
467 	unsigned long flags;
468 
469 	spin_lock_irqsave(&tsk->sighand->siglock, flags);
470 	__flush_itimer_signals(&tsk->pending);
471 	__flush_itimer_signals(&tsk->signal->shared_pending);
472 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
473 }
474 #endif
475 
476 void ignore_signals(struct task_struct *t)
477 {
478 	int i;
479 
480 	for (i = 0; i < _NSIG; ++i)
481 		t->sighand->action[i].sa.sa_handler = SIG_IGN;
482 
483 	flush_signals(t);
484 }
485 
486 /*
487  * Flush all handlers for a task.
488  */
489 
490 void
491 flush_signal_handlers(struct task_struct *t, int force_default)
492 {
493 	int i;
494 	struct k_sigaction *ka = &t->sighand->action[0];
495 	for (i = _NSIG ; i != 0 ; i--) {
496 		if (force_default || ka->sa.sa_handler != SIG_IGN)
497 			ka->sa.sa_handler = SIG_DFL;
498 		ka->sa.sa_flags = 0;
499 #ifdef __ARCH_HAS_SA_RESTORER
500 		ka->sa.sa_restorer = NULL;
501 #endif
502 		sigemptyset(&ka->sa.sa_mask);
503 		ka++;
504 	}
505 }
506 
507 int unhandled_signal(struct task_struct *tsk, int sig)
508 {
509 	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
510 	if (is_global_init(tsk))
511 		return 1;
512 	if (handler != SIG_IGN && handler != SIG_DFL)
513 		return 0;
514 	/* if ptraced, let the tracer determine */
515 	return !tsk->ptrace;
516 }
517 
518 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
519 			   bool *resched_timer)
520 {
521 	struct sigqueue *q, *first = NULL;
522 
523 	/*
524 	 * Collect the siginfo appropriate to this signal.  Check if
525 	 * there is another siginfo for the same signal.
526 	*/
527 	list_for_each_entry(q, &list->list, list) {
528 		if (q->info.si_signo == sig) {
529 			if (first)
530 				goto still_pending;
531 			first = q;
532 		}
533 	}
534 
535 	sigdelset(&list->signal, sig);
536 
537 	if (first) {
538 still_pending:
539 		list_del_init(&first->list);
540 		copy_siginfo(info, &first->info);
541 
542 		*resched_timer =
543 			(first->flags & SIGQUEUE_PREALLOC) &&
544 			(info->si_code == SI_TIMER) &&
545 			(info->si_sys_private);
546 
547 		__sigqueue_free(first);
548 	} else {
549 		/*
550 		 * Ok, it wasn't in the queue.  This must be
551 		 * a fast-pathed signal or we must have been
552 		 * out of queue space.  So zero out the info.
553 		 */
554 		clear_siginfo(info);
555 		info->si_signo = sig;
556 		info->si_errno = 0;
557 		info->si_code = SI_USER;
558 		info->si_pid = 0;
559 		info->si_uid = 0;
560 	}
561 }
562 
563 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
564 			siginfo_t *info, bool *resched_timer)
565 {
566 	int sig = next_signal(pending, mask);
567 
568 	if (sig)
569 		collect_signal(sig, pending, info, resched_timer);
570 	return sig;
571 }
572 
573 /*
574  * Dequeue a signal and return the element to the caller, which is
575  * expected to free it.
576  *
577  * All callers have to hold the siglock.
578  */
579 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
580 {
581 	bool resched_timer = false;
582 	int signr;
583 
584 	/* We only dequeue private signals from ourselves, we don't let
585 	 * signalfd steal them
586 	 */
587 	signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
588 	if (!signr) {
589 		signr = __dequeue_signal(&tsk->signal->shared_pending,
590 					 mask, info, &resched_timer);
591 #ifdef CONFIG_POSIX_TIMERS
592 		/*
593 		 * itimer signal ?
594 		 *
595 		 * itimers are process shared and we restart periodic
596 		 * itimers in the signal delivery path to prevent DoS
597 		 * attacks in the high resolution timer case. This is
598 		 * compliant with the old way of self-restarting
599 		 * itimers, as the SIGALRM is a legacy signal and only
600 		 * queued once. Changing the restart behaviour to
601 		 * restart the timer in the signal dequeue path is
602 		 * reducing the timer noise on heavy loaded !highres
603 		 * systems too.
604 		 */
605 		if (unlikely(signr == SIGALRM)) {
606 			struct hrtimer *tmr = &tsk->signal->real_timer;
607 
608 			if (!hrtimer_is_queued(tmr) &&
609 			    tsk->signal->it_real_incr != 0) {
610 				hrtimer_forward(tmr, tmr->base->get_time(),
611 						tsk->signal->it_real_incr);
612 				hrtimer_restart(tmr);
613 			}
614 		}
615 #endif
616 	}
617 
618 	recalc_sigpending();
619 	if (!signr)
620 		return 0;
621 
622 	if (unlikely(sig_kernel_stop(signr))) {
623 		/*
624 		 * Set a marker that we have dequeued a stop signal.  Our
625 		 * caller might release the siglock and then the pending
626 		 * stop signal it is about to process is no longer in the
627 		 * pending bitmasks, but must still be cleared by a SIGCONT
628 		 * (and overruled by a SIGKILL).  So those cases clear this
629 		 * shared flag after we've set it.  Note that this flag may
630 		 * remain set after the signal we return is ignored or
631 		 * handled.  That doesn't matter because its only purpose
632 		 * is to alert stop-signal processing code when another
633 		 * processor has come along and cleared the flag.
634 		 */
635 		current->jobctl |= JOBCTL_STOP_DEQUEUED;
636 	}
637 #ifdef CONFIG_POSIX_TIMERS
638 	if (resched_timer) {
639 		/*
640 		 * Release the siglock to ensure proper locking order
641 		 * of timer locks outside of siglocks.  Note, we leave
642 		 * irqs disabled here, since the posix-timers code is
643 		 * about to disable them again anyway.
644 		 */
645 		spin_unlock(&tsk->sighand->siglock);
646 		posixtimer_rearm(info);
647 		spin_lock(&tsk->sighand->siglock);
648 
649 		/* Don't expose the si_sys_private value to userspace */
650 		info->si_sys_private = 0;
651 	}
652 #endif
653 	return signr;
654 }
655 
656 /*
657  * Tell a process that it has a new active signal..
658  *
659  * NOTE! we rely on the previous spin_lock to
660  * lock interrupts for us! We can only be called with
661  * "siglock" held, and the local interrupt must
662  * have been disabled when that got acquired!
663  *
664  * No need to set need_resched since signal event passing
665  * goes through ->blocked
666  */
667 void signal_wake_up_state(struct task_struct *t, unsigned int state)
668 {
669 	set_tsk_thread_flag(t, TIF_SIGPENDING);
670 	/*
671 	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
672 	 * case. We don't check t->state here because there is a race with it
673 	 * executing another processor and just now entering stopped state.
674 	 * By using wake_up_state, we ensure the process will wake up and
675 	 * handle its death signal.
676 	 */
677 	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
678 		kick_process(t);
679 }
680 
681 /*
682  * Remove signals in mask from the pending set and queue.
683  * Returns 1 if any signals were found.
684  *
685  * All callers must be holding the siglock.
686  */
687 static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
688 {
689 	struct sigqueue *q, *n;
690 	sigset_t m;
691 
692 	sigandsets(&m, mask, &s->signal);
693 	if (sigisemptyset(&m))
694 		return 0;
695 
696 	sigandnsets(&s->signal, &s->signal, mask);
697 	list_for_each_entry_safe(q, n, &s->list, list) {
698 		if (sigismember(mask, q->info.si_signo)) {
699 			list_del_init(&q->list);
700 			__sigqueue_free(q);
701 		}
702 	}
703 	return 1;
704 }
705 
706 static inline int is_si_special(const struct siginfo *info)
707 {
708 	return info <= SEND_SIG_FORCED;
709 }
710 
711 static inline bool si_fromuser(const struct siginfo *info)
712 {
713 	return info == SEND_SIG_NOINFO ||
714 		(!is_si_special(info) && SI_FROMUSER(info));
715 }
716 
717 /*
718  * called with RCU read lock from check_kill_permission()
719  */
720 static int kill_ok_by_cred(struct task_struct *t)
721 {
722 	const struct cred *cred = current_cred();
723 	const struct cred *tcred = __task_cred(t);
724 
725 	if (uid_eq(cred->euid, tcred->suid) ||
726 	    uid_eq(cred->euid, tcred->uid)  ||
727 	    uid_eq(cred->uid,  tcred->suid) ||
728 	    uid_eq(cred->uid,  tcred->uid))
729 		return 1;
730 
731 	if (ns_capable(tcred->user_ns, CAP_KILL))
732 		return 1;
733 
734 	return 0;
735 }
736 
737 /*
738  * Bad permissions for sending the signal
739  * - the caller must hold the RCU read lock
740  */
741 static int check_kill_permission(int sig, struct siginfo *info,
742 				 struct task_struct *t)
743 {
744 	struct pid *sid;
745 	int error;
746 
747 	if (!valid_signal(sig))
748 		return -EINVAL;
749 
750 	if (!si_fromuser(info))
751 		return 0;
752 
753 	error = audit_signal_info(sig, t); /* Let audit system see the signal */
754 	if (error)
755 		return error;
756 
757 	if (!same_thread_group(current, t) &&
758 	    !kill_ok_by_cred(t)) {
759 		switch (sig) {
760 		case SIGCONT:
761 			sid = task_session(t);
762 			/*
763 			 * We don't return the error if sid == NULL. The
764 			 * task was unhashed, the caller must notice this.
765 			 */
766 			if (!sid || sid == task_session(current))
767 				break;
768 		default:
769 			return -EPERM;
770 		}
771 	}
772 
773 	return security_task_kill(t, info, sig, NULL);
774 }
775 
776 /**
777  * ptrace_trap_notify - schedule trap to notify ptracer
778  * @t: tracee wanting to notify tracer
779  *
780  * This function schedules sticky ptrace trap which is cleared on the next
781  * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
782  * ptracer.
783  *
784  * If @t is running, STOP trap will be taken.  If trapped for STOP and
785  * ptracer is listening for events, tracee is woken up so that it can
786  * re-trap for the new event.  If trapped otherwise, STOP trap will be
787  * eventually taken without returning to userland after the existing traps
788  * are finished by PTRACE_CONT.
789  *
790  * CONTEXT:
791  * Must be called with @task->sighand->siglock held.
792  */
793 static void ptrace_trap_notify(struct task_struct *t)
794 {
795 	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
796 	assert_spin_locked(&t->sighand->siglock);
797 
798 	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
799 	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
800 }
801 
802 /*
803  * Handle magic process-wide effects of stop/continue signals. Unlike
804  * the signal actions, these happen immediately at signal-generation
805  * time regardless of blocking, ignoring, or handling.  This does the
806  * actual continuing for SIGCONT, but not the actual stopping for stop
807  * signals. The process stop is done as a signal action for SIG_DFL.
808  *
809  * Returns true if the signal should be actually delivered, otherwise
810  * it should be dropped.
811  */
812 static bool prepare_signal(int sig, struct task_struct *p, bool force)
813 {
814 	struct signal_struct *signal = p->signal;
815 	struct task_struct *t;
816 	sigset_t flush;
817 
818 	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
819 		if (!(signal->flags & SIGNAL_GROUP_EXIT))
820 			return sig == SIGKILL;
821 		/*
822 		 * The process is in the middle of dying, nothing to do.
823 		 */
824 	} else if (sig_kernel_stop(sig)) {
825 		/*
826 		 * This is a stop signal.  Remove SIGCONT from all queues.
827 		 */
828 		siginitset(&flush, sigmask(SIGCONT));
829 		flush_sigqueue_mask(&flush, &signal->shared_pending);
830 		for_each_thread(p, t)
831 			flush_sigqueue_mask(&flush, &t->pending);
832 	} else if (sig == SIGCONT) {
833 		unsigned int why;
834 		/*
835 		 * Remove all stop signals from all queues, wake all threads.
836 		 */
837 		siginitset(&flush, SIG_KERNEL_STOP_MASK);
838 		flush_sigqueue_mask(&flush, &signal->shared_pending);
839 		for_each_thread(p, t) {
840 			flush_sigqueue_mask(&flush, &t->pending);
841 			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
842 			if (likely(!(t->ptrace & PT_SEIZED)))
843 				wake_up_state(t, __TASK_STOPPED);
844 			else
845 				ptrace_trap_notify(t);
846 		}
847 
848 		/*
849 		 * Notify the parent with CLD_CONTINUED if we were stopped.
850 		 *
851 		 * If we were in the middle of a group stop, we pretend it
852 		 * was already finished, and then continued. Since SIGCHLD
853 		 * doesn't queue we report only CLD_STOPPED, as if the next
854 		 * CLD_CONTINUED was dropped.
855 		 */
856 		why = 0;
857 		if (signal->flags & SIGNAL_STOP_STOPPED)
858 			why |= SIGNAL_CLD_CONTINUED;
859 		else if (signal->group_stop_count)
860 			why |= SIGNAL_CLD_STOPPED;
861 
862 		if (why) {
863 			/*
864 			 * The first thread which returns from do_signal_stop()
865 			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
866 			 * notify its parent. See get_signal_to_deliver().
867 			 */
868 			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
869 			signal->group_stop_count = 0;
870 			signal->group_exit_code = 0;
871 		}
872 	}
873 
874 	return !sig_ignored(p, sig, force);
875 }
876 
877 /*
878  * Test if P wants to take SIG.  After we've checked all threads with this,
879  * it's equivalent to finding no threads not blocking SIG.  Any threads not
880  * blocking SIG were ruled out because they are not running and already
881  * have pending signals.  Such threads will dequeue from the shared queue
882  * as soon as they're available, so putting the signal on the shared queue
883  * will be equivalent to sending it to one such thread.
884  */
885 static inline int wants_signal(int sig, struct task_struct *p)
886 {
887 	if (sigismember(&p->blocked, sig))
888 		return 0;
889 	if (p->flags & PF_EXITING)
890 		return 0;
891 	if (sig == SIGKILL)
892 		return 1;
893 	if (task_is_stopped_or_traced(p))
894 		return 0;
895 	return task_curr(p) || !signal_pending(p);
896 }
897 
898 static void complete_signal(int sig, struct task_struct *p, int group)
899 {
900 	struct signal_struct *signal = p->signal;
901 	struct task_struct *t;
902 
903 	/*
904 	 * Now find a thread we can wake up to take the signal off the queue.
905 	 *
906 	 * If the main thread wants the signal, it gets first crack.
907 	 * Probably the least surprising to the average bear.
908 	 */
909 	if (wants_signal(sig, p))
910 		t = p;
911 	else if (!group || thread_group_empty(p))
912 		/*
913 		 * There is just one thread and it does not need to be woken.
914 		 * It will dequeue unblocked signals before it runs again.
915 		 */
916 		return;
917 	else {
918 		/*
919 		 * Otherwise try to find a suitable thread.
920 		 */
921 		t = signal->curr_target;
922 		while (!wants_signal(sig, t)) {
923 			t = next_thread(t);
924 			if (t == signal->curr_target)
925 				/*
926 				 * No thread needs to be woken.
927 				 * Any eligible threads will see
928 				 * the signal in the queue soon.
929 				 */
930 				return;
931 		}
932 		signal->curr_target = t;
933 	}
934 
935 	/*
936 	 * Found a killable thread.  If the signal will be fatal,
937 	 * then start taking the whole group down immediately.
938 	 */
939 	if (sig_fatal(p, sig) &&
940 	    !(signal->flags & SIGNAL_GROUP_EXIT) &&
941 	    !sigismember(&t->real_blocked, sig) &&
942 	    (sig == SIGKILL || !p->ptrace)) {
943 		/*
944 		 * This signal will be fatal to the whole group.
945 		 */
946 		if (!sig_kernel_coredump(sig)) {
947 			/*
948 			 * Start a group exit and wake everybody up.
949 			 * This way we don't have other threads
950 			 * running and doing things after a slower
951 			 * thread has the fatal signal pending.
952 			 */
953 			signal->flags = SIGNAL_GROUP_EXIT;
954 			signal->group_exit_code = sig;
955 			signal->group_stop_count = 0;
956 			t = p;
957 			do {
958 				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
959 				sigaddset(&t->pending.signal, SIGKILL);
960 				signal_wake_up(t, 1);
961 			} while_each_thread(p, t);
962 			return;
963 		}
964 	}
965 
966 	/*
967 	 * The signal is already in the shared-pending queue.
968 	 * Tell the chosen thread to wake up and dequeue it.
969 	 */
970 	signal_wake_up(t, sig == SIGKILL);
971 	return;
972 }
973 
974 static inline int legacy_queue(struct sigpending *signals, int sig)
975 {
976 	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
977 }
978 
979 #ifdef CONFIG_USER_NS
980 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
981 {
982 	if (current_user_ns() == task_cred_xxx(t, user_ns))
983 		return;
984 
985 	if (SI_FROMKERNEL(info))
986 		return;
987 
988 	rcu_read_lock();
989 	info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
990 					make_kuid(current_user_ns(), info->si_uid));
991 	rcu_read_unlock();
992 }
993 #else
994 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
995 {
996 	return;
997 }
998 #endif
999 
1000 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1001 			int group, int from_ancestor_ns)
1002 {
1003 	struct sigpending *pending;
1004 	struct sigqueue *q;
1005 	int override_rlimit;
1006 	int ret = 0, result;
1007 
1008 	assert_spin_locked(&t->sighand->siglock);
1009 
1010 	result = TRACE_SIGNAL_IGNORED;
1011 	if (!prepare_signal(sig, t,
1012 			from_ancestor_ns || (info == SEND_SIG_FORCED)))
1013 		goto ret;
1014 
1015 	pending = group ? &t->signal->shared_pending : &t->pending;
1016 	/*
1017 	 * Short-circuit ignored signals and support queuing
1018 	 * exactly one non-rt signal, so that we can get more
1019 	 * detailed information about the cause of the signal.
1020 	 */
1021 	result = TRACE_SIGNAL_ALREADY_PENDING;
1022 	if (legacy_queue(pending, sig))
1023 		goto ret;
1024 
1025 	result = TRACE_SIGNAL_DELIVERED;
1026 	/*
1027 	 * fast-pathed signals for kernel-internal things like SIGSTOP
1028 	 * or SIGKILL.
1029 	 */
1030 	if (info == SEND_SIG_FORCED)
1031 		goto out_set;
1032 
1033 	/*
1034 	 * Real-time signals must be queued if sent by sigqueue, or
1035 	 * some other real-time mechanism.  It is implementation
1036 	 * defined whether kill() does so.  We attempt to do so, on
1037 	 * the principle of least surprise, but since kill is not
1038 	 * allowed to fail with EAGAIN when low on memory we just
1039 	 * make sure at least one signal gets delivered and don't
1040 	 * pass on the info struct.
1041 	 */
1042 	if (sig < SIGRTMIN)
1043 		override_rlimit = (is_si_special(info) || info->si_code >= 0);
1044 	else
1045 		override_rlimit = 0;
1046 
1047 	q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
1048 	if (q) {
1049 		list_add_tail(&q->list, &pending->list);
1050 		switch ((unsigned long) info) {
1051 		case (unsigned long) SEND_SIG_NOINFO:
1052 			clear_siginfo(&q->info);
1053 			q->info.si_signo = sig;
1054 			q->info.si_errno = 0;
1055 			q->info.si_code = SI_USER;
1056 			q->info.si_pid = task_tgid_nr_ns(current,
1057 							task_active_pid_ns(t));
1058 			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1059 			break;
1060 		case (unsigned long) SEND_SIG_PRIV:
1061 			clear_siginfo(&q->info);
1062 			q->info.si_signo = sig;
1063 			q->info.si_errno = 0;
1064 			q->info.si_code = SI_KERNEL;
1065 			q->info.si_pid = 0;
1066 			q->info.si_uid = 0;
1067 			break;
1068 		default:
1069 			copy_siginfo(&q->info, info);
1070 			if (from_ancestor_ns)
1071 				q->info.si_pid = 0;
1072 			break;
1073 		}
1074 
1075 		userns_fixup_signal_uid(&q->info, t);
1076 
1077 	} else if (!is_si_special(info)) {
1078 		if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1079 			/*
1080 			 * Queue overflow, abort.  We may abort if the
1081 			 * signal was rt and sent by user using something
1082 			 * other than kill().
1083 			 */
1084 			result = TRACE_SIGNAL_OVERFLOW_FAIL;
1085 			ret = -EAGAIN;
1086 			goto ret;
1087 		} else {
1088 			/*
1089 			 * This is a silent loss of information.  We still
1090 			 * send the signal, but the *info bits are lost.
1091 			 */
1092 			result = TRACE_SIGNAL_LOSE_INFO;
1093 		}
1094 	}
1095 
1096 out_set:
1097 	signalfd_notify(t, sig);
1098 	sigaddset(&pending->signal, sig);
1099 	complete_signal(sig, t, group);
1100 ret:
1101 	trace_signal_generate(sig, info, t, group, result);
1102 	return ret;
1103 }
1104 
1105 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1106 			int group)
1107 {
1108 	int from_ancestor_ns = 0;
1109 
1110 #ifdef CONFIG_PID_NS
1111 	from_ancestor_ns = si_fromuser(info) &&
1112 			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1113 #endif
1114 
1115 	return __send_signal(sig, info, t, group, from_ancestor_ns);
1116 }
1117 
1118 static void print_fatal_signal(int signr)
1119 {
1120 	struct pt_regs *regs = signal_pt_regs();
1121 	pr_info("potentially unexpected fatal signal %d.\n", signr);
1122 
1123 #if defined(__i386__) && !defined(__arch_um__)
1124 	pr_info("code at %08lx: ", regs->ip);
1125 	{
1126 		int i;
1127 		for (i = 0; i < 16; i++) {
1128 			unsigned char insn;
1129 
1130 			if (get_user(insn, (unsigned char *)(regs->ip + i)))
1131 				break;
1132 			pr_cont("%02x ", insn);
1133 		}
1134 	}
1135 	pr_cont("\n");
1136 #endif
1137 	preempt_disable();
1138 	show_regs(regs);
1139 	preempt_enable();
1140 }
1141 
1142 static int __init setup_print_fatal_signals(char *str)
1143 {
1144 	get_option (&str, &print_fatal_signals);
1145 
1146 	return 1;
1147 }
1148 
1149 __setup("print-fatal-signals=", setup_print_fatal_signals);
1150 
1151 int
1152 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1153 {
1154 	return send_signal(sig, info, p, 1);
1155 }
1156 
1157 static int
1158 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1159 {
1160 	return send_signal(sig, info, t, 0);
1161 }
1162 
1163 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1164 			bool group)
1165 {
1166 	unsigned long flags;
1167 	int ret = -ESRCH;
1168 
1169 	if (lock_task_sighand(p, &flags)) {
1170 		ret = send_signal(sig, info, p, group);
1171 		unlock_task_sighand(p, &flags);
1172 	}
1173 
1174 	return ret;
1175 }
1176 
1177 /*
1178  * Force a signal that the process can't ignore: if necessary
1179  * we unblock the signal and change any SIG_IGN to SIG_DFL.
1180  *
1181  * Note: If we unblock the signal, we always reset it to SIG_DFL,
1182  * since we do not want to have a signal handler that was blocked
1183  * be invoked when user space had explicitly blocked it.
1184  *
1185  * We don't want to have recursive SIGSEGV's etc, for example,
1186  * that is why we also clear SIGNAL_UNKILLABLE.
1187  */
1188 int
1189 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1190 {
1191 	unsigned long int flags;
1192 	int ret, blocked, ignored;
1193 	struct k_sigaction *action;
1194 
1195 	spin_lock_irqsave(&t->sighand->siglock, flags);
1196 	action = &t->sighand->action[sig-1];
1197 	ignored = action->sa.sa_handler == SIG_IGN;
1198 	blocked = sigismember(&t->blocked, sig);
1199 	if (blocked || ignored) {
1200 		action->sa.sa_handler = SIG_DFL;
1201 		if (blocked) {
1202 			sigdelset(&t->blocked, sig);
1203 			recalc_sigpending_and_wake(t);
1204 		}
1205 	}
1206 	/*
1207 	 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1208 	 * debugging to leave init killable.
1209 	 */
1210 	if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1211 		t->signal->flags &= ~SIGNAL_UNKILLABLE;
1212 	ret = specific_send_sig_info(sig, info, t);
1213 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
1214 
1215 	return ret;
1216 }
1217 
1218 /*
1219  * Nuke all other threads in the group.
1220  */
1221 int zap_other_threads(struct task_struct *p)
1222 {
1223 	struct task_struct *t = p;
1224 	int count = 0;
1225 
1226 	p->signal->group_stop_count = 0;
1227 
1228 	while_each_thread(p, t) {
1229 		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1230 		count++;
1231 
1232 		/* Don't bother with already dead threads */
1233 		if (t->exit_state)
1234 			continue;
1235 		sigaddset(&t->pending.signal, SIGKILL);
1236 		signal_wake_up(t, 1);
1237 	}
1238 
1239 	return count;
1240 }
1241 
1242 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1243 					   unsigned long *flags)
1244 {
1245 	struct sighand_struct *sighand;
1246 
1247 	for (;;) {
1248 		/*
1249 		 * Disable interrupts early to avoid deadlocks.
1250 		 * See rcu_read_unlock() comment header for details.
1251 		 */
1252 		local_irq_save(*flags);
1253 		rcu_read_lock();
1254 		sighand = rcu_dereference(tsk->sighand);
1255 		if (unlikely(sighand == NULL)) {
1256 			rcu_read_unlock();
1257 			local_irq_restore(*flags);
1258 			break;
1259 		}
1260 		/*
1261 		 * This sighand can be already freed and even reused, but
1262 		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1263 		 * initializes ->siglock: this slab can't go away, it has
1264 		 * the same object type, ->siglock can't be reinitialized.
1265 		 *
1266 		 * We need to ensure that tsk->sighand is still the same
1267 		 * after we take the lock, we can race with de_thread() or
1268 		 * __exit_signal(). In the latter case the next iteration
1269 		 * must see ->sighand == NULL.
1270 		 */
1271 		spin_lock(&sighand->siglock);
1272 		if (likely(sighand == tsk->sighand)) {
1273 			rcu_read_unlock();
1274 			break;
1275 		}
1276 		spin_unlock(&sighand->siglock);
1277 		rcu_read_unlock();
1278 		local_irq_restore(*flags);
1279 	}
1280 
1281 	return sighand;
1282 }
1283 
1284 /*
1285  * send signal info to all the members of a group
1286  */
1287 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1288 {
1289 	int ret;
1290 
1291 	rcu_read_lock();
1292 	ret = check_kill_permission(sig, info, p);
1293 	rcu_read_unlock();
1294 
1295 	if (!ret && sig)
1296 		ret = do_send_sig_info(sig, info, p, true);
1297 
1298 	return ret;
1299 }
1300 
1301 /*
1302  * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1303  * control characters do (^C, ^Z etc)
1304  * - the caller must hold at least a readlock on tasklist_lock
1305  */
1306 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1307 {
1308 	struct task_struct *p = NULL;
1309 	int retval, success;
1310 
1311 	success = 0;
1312 	retval = -ESRCH;
1313 	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1314 		int err = group_send_sig_info(sig, info, p);
1315 		success |= !err;
1316 		retval = err;
1317 	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1318 	return success ? 0 : retval;
1319 }
1320 
1321 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1322 {
1323 	int error = -ESRCH;
1324 	struct task_struct *p;
1325 
1326 	for (;;) {
1327 		rcu_read_lock();
1328 		p = pid_task(pid, PIDTYPE_PID);
1329 		if (p)
1330 			error = group_send_sig_info(sig, info, p);
1331 		rcu_read_unlock();
1332 		if (likely(!p || error != -ESRCH))
1333 			return error;
1334 
1335 		/*
1336 		 * The task was unhashed in between, try again.  If it
1337 		 * is dead, pid_task() will return NULL, if we race with
1338 		 * de_thread() it will find the new leader.
1339 		 */
1340 	}
1341 }
1342 
1343 static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1344 {
1345 	int error;
1346 	rcu_read_lock();
1347 	error = kill_pid_info(sig, info, find_vpid(pid));
1348 	rcu_read_unlock();
1349 	return error;
1350 }
1351 
1352 static int kill_as_cred_perm(const struct cred *cred,
1353 			     struct task_struct *target)
1354 {
1355 	const struct cred *pcred = __task_cred(target);
1356 	if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1357 	    !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
1358 		return 0;
1359 	return 1;
1360 }
1361 
1362 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1363 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1364 			 const struct cred *cred)
1365 {
1366 	int ret = -EINVAL;
1367 	struct task_struct *p;
1368 	unsigned long flags;
1369 
1370 	if (!valid_signal(sig))
1371 		return ret;
1372 
1373 	rcu_read_lock();
1374 	p = pid_task(pid, PIDTYPE_PID);
1375 	if (!p) {
1376 		ret = -ESRCH;
1377 		goto out_unlock;
1378 	}
1379 	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1380 		ret = -EPERM;
1381 		goto out_unlock;
1382 	}
1383 	ret = security_task_kill(p, info, sig, cred);
1384 	if (ret)
1385 		goto out_unlock;
1386 
1387 	if (sig) {
1388 		if (lock_task_sighand(p, &flags)) {
1389 			ret = __send_signal(sig, info, p, 1, 0);
1390 			unlock_task_sighand(p, &flags);
1391 		} else
1392 			ret = -ESRCH;
1393 	}
1394 out_unlock:
1395 	rcu_read_unlock();
1396 	return ret;
1397 }
1398 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1399 
1400 /*
1401  * kill_something_info() interprets pid in interesting ways just like kill(2).
1402  *
1403  * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1404  * is probably wrong.  Should make it like BSD or SYSV.
1405  */
1406 
1407 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1408 {
1409 	int ret;
1410 
1411 	if (pid > 0) {
1412 		rcu_read_lock();
1413 		ret = kill_pid_info(sig, info, find_vpid(pid));
1414 		rcu_read_unlock();
1415 		return ret;
1416 	}
1417 
1418 	/* -INT_MIN is undefined.  Exclude this case to avoid a UBSAN warning */
1419 	if (pid == INT_MIN)
1420 		return -ESRCH;
1421 
1422 	read_lock(&tasklist_lock);
1423 	if (pid != -1) {
1424 		ret = __kill_pgrp_info(sig, info,
1425 				pid ? find_vpid(-pid) : task_pgrp(current));
1426 	} else {
1427 		int retval = 0, count = 0;
1428 		struct task_struct * p;
1429 
1430 		for_each_process(p) {
1431 			if (task_pid_vnr(p) > 1 &&
1432 					!same_thread_group(p, current)) {
1433 				int err = group_send_sig_info(sig, info, p);
1434 				++count;
1435 				if (err != -EPERM)
1436 					retval = err;
1437 			}
1438 		}
1439 		ret = count ? retval : -ESRCH;
1440 	}
1441 	read_unlock(&tasklist_lock);
1442 
1443 	return ret;
1444 }
1445 
1446 /*
1447  * These are for backward compatibility with the rest of the kernel source.
1448  */
1449 
1450 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1451 {
1452 	/*
1453 	 * Make sure legacy kernel users don't send in bad values
1454 	 * (normal paths check this in check_kill_permission).
1455 	 */
1456 	if (!valid_signal(sig))
1457 		return -EINVAL;
1458 
1459 	return do_send_sig_info(sig, info, p, false);
1460 }
1461 
1462 #define __si_special(priv) \
1463 	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1464 
1465 int
1466 send_sig(int sig, struct task_struct *p, int priv)
1467 {
1468 	return send_sig_info(sig, __si_special(priv), p);
1469 }
1470 
1471 void
1472 force_sig(int sig, struct task_struct *p)
1473 {
1474 	force_sig_info(sig, SEND_SIG_PRIV, p);
1475 }
1476 
1477 /*
1478  * When things go south during signal handling, we
1479  * will force a SIGSEGV. And if the signal that caused
1480  * the problem was already a SIGSEGV, we'll want to
1481  * make sure we don't even try to deliver the signal..
1482  */
1483 int
1484 force_sigsegv(int sig, struct task_struct *p)
1485 {
1486 	if (sig == SIGSEGV) {
1487 		unsigned long flags;
1488 		spin_lock_irqsave(&p->sighand->siglock, flags);
1489 		p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1490 		spin_unlock_irqrestore(&p->sighand->siglock, flags);
1491 	}
1492 	force_sig(SIGSEGV, p);
1493 	return 0;
1494 }
1495 
1496 int force_sig_fault(int sig, int code, void __user *addr
1497 	___ARCH_SI_TRAPNO(int trapno)
1498 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1499 	, struct task_struct *t)
1500 {
1501 	struct siginfo info;
1502 
1503 	clear_siginfo(&info);
1504 	info.si_signo = sig;
1505 	info.si_errno = 0;
1506 	info.si_code  = code;
1507 	info.si_addr  = addr;
1508 #ifdef __ARCH_SI_TRAPNO
1509 	info.si_trapno = trapno;
1510 #endif
1511 #ifdef __ia64__
1512 	info.si_imm = imm;
1513 	info.si_flags = flags;
1514 	info.si_isr = isr;
1515 #endif
1516 	return force_sig_info(info.si_signo, &info, t);
1517 }
1518 
1519 int send_sig_fault(int sig, int code, void __user *addr
1520 	___ARCH_SI_TRAPNO(int trapno)
1521 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1522 	, struct task_struct *t)
1523 {
1524 	struct siginfo info;
1525 
1526 	clear_siginfo(&info);
1527 	info.si_signo = sig;
1528 	info.si_errno = 0;
1529 	info.si_code  = code;
1530 	info.si_addr  = addr;
1531 #ifdef __ARCH_SI_TRAPNO
1532 	info.si_trapno = trapno;
1533 #endif
1534 #ifdef __ia64__
1535 	info.si_imm = imm;
1536 	info.si_flags = flags;
1537 	info.si_isr = isr;
1538 #endif
1539 	return send_sig_info(info.si_signo, &info, t);
1540 }
1541 
1542 #if defined(BUS_MCEERR_AO) && defined(BUS_MCEERR_AR)
1543 int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1544 {
1545 	struct siginfo info;
1546 
1547 	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1548 	clear_siginfo(&info);
1549 	info.si_signo = SIGBUS;
1550 	info.si_errno = 0;
1551 	info.si_code = code;
1552 	info.si_addr = addr;
1553 	info.si_addr_lsb = lsb;
1554 	return force_sig_info(info.si_signo, &info, t);
1555 }
1556 
1557 int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1558 {
1559 	struct siginfo info;
1560 
1561 	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1562 	clear_siginfo(&info);
1563 	info.si_signo = SIGBUS;
1564 	info.si_errno = 0;
1565 	info.si_code = code;
1566 	info.si_addr = addr;
1567 	info.si_addr_lsb = lsb;
1568 	return send_sig_info(info.si_signo, &info, t);
1569 }
1570 EXPORT_SYMBOL(send_sig_mceerr);
1571 #endif
1572 
1573 #ifdef SEGV_BNDERR
1574 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1575 {
1576 	struct siginfo info;
1577 
1578 	clear_siginfo(&info);
1579 	info.si_signo = SIGSEGV;
1580 	info.si_errno = 0;
1581 	info.si_code  = SEGV_BNDERR;
1582 	info.si_addr  = addr;
1583 	info.si_lower = lower;
1584 	info.si_upper = upper;
1585 	return force_sig_info(info.si_signo, &info, current);
1586 }
1587 #endif
1588 
1589 #ifdef SEGV_PKUERR
1590 int force_sig_pkuerr(void __user *addr, u32 pkey)
1591 {
1592 	struct siginfo info;
1593 
1594 	clear_siginfo(&info);
1595 	info.si_signo = SIGSEGV;
1596 	info.si_errno = 0;
1597 	info.si_code  = SEGV_PKUERR;
1598 	info.si_addr  = addr;
1599 	info.si_pkey  = pkey;
1600 	return force_sig_info(info.si_signo, &info, current);
1601 }
1602 #endif
1603 
1604 /* For the crazy architectures that include trap information in
1605  * the errno field, instead of an actual errno value.
1606  */
1607 int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1608 {
1609 	struct siginfo info;
1610 
1611 	clear_siginfo(&info);
1612 	info.si_signo = SIGTRAP;
1613 	info.si_errno = errno;
1614 	info.si_code  = TRAP_HWBKPT;
1615 	info.si_addr  = addr;
1616 	return force_sig_info(info.si_signo, &info, current);
1617 }
1618 
1619 int kill_pgrp(struct pid *pid, int sig, int priv)
1620 {
1621 	int ret;
1622 
1623 	read_lock(&tasklist_lock);
1624 	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1625 	read_unlock(&tasklist_lock);
1626 
1627 	return ret;
1628 }
1629 EXPORT_SYMBOL(kill_pgrp);
1630 
1631 int kill_pid(struct pid *pid, int sig, int priv)
1632 {
1633 	return kill_pid_info(sig, __si_special(priv), pid);
1634 }
1635 EXPORT_SYMBOL(kill_pid);
1636 
1637 /*
1638  * These functions support sending signals using preallocated sigqueue
1639  * structures.  This is needed "because realtime applications cannot
1640  * afford to lose notifications of asynchronous events, like timer
1641  * expirations or I/O completions".  In the case of POSIX Timers
1642  * we allocate the sigqueue structure from the timer_create.  If this
1643  * allocation fails we are able to report the failure to the application
1644  * with an EAGAIN error.
1645  */
1646 struct sigqueue *sigqueue_alloc(void)
1647 {
1648 	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1649 
1650 	if (q)
1651 		q->flags |= SIGQUEUE_PREALLOC;
1652 
1653 	return q;
1654 }
1655 
1656 void sigqueue_free(struct sigqueue *q)
1657 {
1658 	unsigned long flags;
1659 	spinlock_t *lock = &current->sighand->siglock;
1660 
1661 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1662 	/*
1663 	 * We must hold ->siglock while testing q->list
1664 	 * to serialize with collect_signal() or with
1665 	 * __exit_signal()->flush_sigqueue().
1666 	 */
1667 	spin_lock_irqsave(lock, flags);
1668 	q->flags &= ~SIGQUEUE_PREALLOC;
1669 	/*
1670 	 * If it is queued it will be freed when dequeued,
1671 	 * like the "regular" sigqueue.
1672 	 */
1673 	if (!list_empty(&q->list))
1674 		q = NULL;
1675 	spin_unlock_irqrestore(lock, flags);
1676 
1677 	if (q)
1678 		__sigqueue_free(q);
1679 }
1680 
1681 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1682 {
1683 	int sig = q->info.si_signo;
1684 	struct sigpending *pending;
1685 	unsigned long flags;
1686 	int ret, result;
1687 
1688 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1689 
1690 	ret = -1;
1691 	if (!likely(lock_task_sighand(t, &flags)))
1692 		goto ret;
1693 
1694 	ret = 1; /* the signal is ignored */
1695 	result = TRACE_SIGNAL_IGNORED;
1696 	if (!prepare_signal(sig, t, false))
1697 		goto out;
1698 
1699 	ret = 0;
1700 	if (unlikely(!list_empty(&q->list))) {
1701 		/*
1702 		 * If an SI_TIMER entry is already queue just increment
1703 		 * the overrun count.
1704 		 */
1705 		BUG_ON(q->info.si_code != SI_TIMER);
1706 		q->info.si_overrun++;
1707 		result = TRACE_SIGNAL_ALREADY_PENDING;
1708 		goto out;
1709 	}
1710 	q->info.si_overrun = 0;
1711 
1712 	signalfd_notify(t, sig);
1713 	pending = group ? &t->signal->shared_pending : &t->pending;
1714 	list_add_tail(&q->list, &pending->list);
1715 	sigaddset(&pending->signal, sig);
1716 	complete_signal(sig, t, group);
1717 	result = TRACE_SIGNAL_DELIVERED;
1718 out:
1719 	trace_signal_generate(sig, &q->info, t, group, result);
1720 	unlock_task_sighand(t, &flags);
1721 ret:
1722 	return ret;
1723 }
1724 
1725 /*
1726  * Let a parent know about the death of a child.
1727  * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1728  *
1729  * Returns true if our parent ignored us and so we've switched to
1730  * self-reaping.
1731  */
1732 bool do_notify_parent(struct task_struct *tsk, int sig)
1733 {
1734 	struct siginfo info;
1735 	unsigned long flags;
1736 	struct sighand_struct *psig;
1737 	bool autoreap = false;
1738 	u64 utime, stime;
1739 
1740 	BUG_ON(sig == -1);
1741 
1742  	/* do_notify_parent_cldstop should have been called instead.  */
1743  	BUG_ON(task_is_stopped_or_traced(tsk));
1744 
1745 	BUG_ON(!tsk->ptrace &&
1746 	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1747 
1748 	if (sig != SIGCHLD) {
1749 		/*
1750 		 * This is only possible if parent == real_parent.
1751 		 * Check if it has changed security domain.
1752 		 */
1753 		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1754 			sig = SIGCHLD;
1755 	}
1756 
1757 	clear_siginfo(&info);
1758 	info.si_signo = sig;
1759 	info.si_errno = 0;
1760 	/*
1761 	 * We are under tasklist_lock here so our parent is tied to
1762 	 * us and cannot change.
1763 	 *
1764 	 * task_active_pid_ns will always return the same pid namespace
1765 	 * until a task passes through release_task.
1766 	 *
1767 	 * write_lock() currently calls preempt_disable() which is the
1768 	 * same as rcu_read_lock(), but according to Oleg, this is not
1769 	 * correct to rely on this
1770 	 */
1771 	rcu_read_lock();
1772 	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1773 	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1774 				       task_uid(tsk));
1775 	rcu_read_unlock();
1776 
1777 	task_cputime(tsk, &utime, &stime);
1778 	info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1779 	info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1780 
1781 	info.si_status = tsk->exit_code & 0x7f;
1782 	if (tsk->exit_code & 0x80)
1783 		info.si_code = CLD_DUMPED;
1784 	else if (tsk->exit_code & 0x7f)
1785 		info.si_code = CLD_KILLED;
1786 	else {
1787 		info.si_code = CLD_EXITED;
1788 		info.si_status = tsk->exit_code >> 8;
1789 	}
1790 
1791 	psig = tsk->parent->sighand;
1792 	spin_lock_irqsave(&psig->siglock, flags);
1793 	if (!tsk->ptrace && sig == SIGCHLD &&
1794 	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1795 	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1796 		/*
1797 		 * We are exiting and our parent doesn't care.  POSIX.1
1798 		 * defines special semantics for setting SIGCHLD to SIG_IGN
1799 		 * or setting the SA_NOCLDWAIT flag: we should be reaped
1800 		 * automatically and not left for our parent's wait4 call.
1801 		 * Rather than having the parent do it as a magic kind of
1802 		 * signal handler, we just set this to tell do_exit that we
1803 		 * can be cleaned up without becoming a zombie.  Note that
1804 		 * we still call __wake_up_parent in this case, because a
1805 		 * blocked sys_wait4 might now return -ECHILD.
1806 		 *
1807 		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1808 		 * is implementation-defined: we do (if you don't want
1809 		 * it, just use SIG_IGN instead).
1810 		 */
1811 		autoreap = true;
1812 		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1813 			sig = 0;
1814 	}
1815 	if (valid_signal(sig) && sig)
1816 		__group_send_sig_info(sig, &info, tsk->parent);
1817 	__wake_up_parent(tsk, tsk->parent);
1818 	spin_unlock_irqrestore(&psig->siglock, flags);
1819 
1820 	return autoreap;
1821 }
1822 
1823 /**
1824  * do_notify_parent_cldstop - notify parent of stopped/continued state change
1825  * @tsk: task reporting the state change
1826  * @for_ptracer: the notification is for ptracer
1827  * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1828  *
1829  * Notify @tsk's parent that the stopped/continued state has changed.  If
1830  * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1831  * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1832  *
1833  * CONTEXT:
1834  * Must be called with tasklist_lock at least read locked.
1835  */
1836 static void do_notify_parent_cldstop(struct task_struct *tsk,
1837 				     bool for_ptracer, int why)
1838 {
1839 	struct siginfo info;
1840 	unsigned long flags;
1841 	struct task_struct *parent;
1842 	struct sighand_struct *sighand;
1843 	u64 utime, stime;
1844 
1845 	if (for_ptracer) {
1846 		parent = tsk->parent;
1847 	} else {
1848 		tsk = tsk->group_leader;
1849 		parent = tsk->real_parent;
1850 	}
1851 
1852 	clear_siginfo(&info);
1853 	info.si_signo = SIGCHLD;
1854 	info.si_errno = 0;
1855 	/*
1856 	 * see comment in do_notify_parent() about the following 4 lines
1857 	 */
1858 	rcu_read_lock();
1859 	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1860 	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1861 	rcu_read_unlock();
1862 
1863 	task_cputime(tsk, &utime, &stime);
1864 	info.si_utime = nsec_to_clock_t(utime);
1865 	info.si_stime = nsec_to_clock_t(stime);
1866 
1867  	info.si_code = why;
1868  	switch (why) {
1869  	case CLD_CONTINUED:
1870  		info.si_status = SIGCONT;
1871  		break;
1872  	case CLD_STOPPED:
1873  		info.si_status = tsk->signal->group_exit_code & 0x7f;
1874  		break;
1875  	case CLD_TRAPPED:
1876  		info.si_status = tsk->exit_code & 0x7f;
1877  		break;
1878  	default:
1879  		BUG();
1880  	}
1881 
1882 	sighand = parent->sighand;
1883 	spin_lock_irqsave(&sighand->siglock, flags);
1884 	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1885 	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1886 		__group_send_sig_info(SIGCHLD, &info, parent);
1887 	/*
1888 	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1889 	 */
1890 	__wake_up_parent(tsk, parent);
1891 	spin_unlock_irqrestore(&sighand->siglock, flags);
1892 }
1893 
1894 static inline int may_ptrace_stop(void)
1895 {
1896 	if (!likely(current->ptrace))
1897 		return 0;
1898 	/*
1899 	 * Are we in the middle of do_coredump?
1900 	 * If so and our tracer is also part of the coredump stopping
1901 	 * is a deadlock situation, and pointless because our tracer
1902 	 * is dead so don't allow us to stop.
1903 	 * If SIGKILL was already sent before the caller unlocked
1904 	 * ->siglock we must see ->core_state != NULL. Otherwise it
1905 	 * is safe to enter schedule().
1906 	 *
1907 	 * This is almost outdated, a task with the pending SIGKILL can't
1908 	 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1909 	 * after SIGKILL was already dequeued.
1910 	 */
1911 	if (unlikely(current->mm->core_state) &&
1912 	    unlikely(current->mm == current->parent->mm))
1913 		return 0;
1914 
1915 	return 1;
1916 }
1917 
1918 /*
1919  * Return non-zero if there is a SIGKILL that should be waking us up.
1920  * Called with the siglock held.
1921  */
1922 static int sigkill_pending(struct task_struct *tsk)
1923 {
1924 	return	sigismember(&tsk->pending.signal, SIGKILL) ||
1925 		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1926 }
1927 
1928 /*
1929  * This must be called with current->sighand->siglock held.
1930  *
1931  * This should be the path for all ptrace stops.
1932  * We always set current->last_siginfo while stopped here.
1933  * That makes it a way to test a stopped process for
1934  * being ptrace-stopped vs being job-control-stopped.
1935  *
1936  * If we actually decide not to stop at all because the tracer
1937  * is gone, we keep current->exit_code unless clear_code.
1938  */
1939 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1940 	__releases(&current->sighand->siglock)
1941 	__acquires(&current->sighand->siglock)
1942 {
1943 	bool gstop_done = false;
1944 
1945 	if (arch_ptrace_stop_needed(exit_code, info)) {
1946 		/*
1947 		 * The arch code has something special to do before a
1948 		 * ptrace stop.  This is allowed to block, e.g. for faults
1949 		 * on user stack pages.  We can't keep the siglock while
1950 		 * calling arch_ptrace_stop, so we must release it now.
1951 		 * To preserve proper semantics, we must do this before
1952 		 * any signal bookkeeping like checking group_stop_count.
1953 		 * Meanwhile, a SIGKILL could come in before we retake the
1954 		 * siglock.  That must prevent us from sleeping in TASK_TRACED.
1955 		 * So after regaining the lock, we must check for SIGKILL.
1956 		 */
1957 		spin_unlock_irq(&current->sighand->siglock);
1958 		arch_ptrace_stop(exit_code, info);
1959 		spin_lock_irq(&current->sighand->siglock);
1960 		if (sigkill_pending(current))
1961 			return;
1962 	}
1963 
1964 	/*
1965 	 * We're committing to trapping.  TRACED should be visible before
1966 	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1967 	 * Also, transition to TRACED and updates to ->jobctl should be
1968 	 * atomic with respect to siglock and should be done after the arch
1969 	 * hook as siglock is released and regrabbed across it.
1970 	 */
1971 	set_current_state(TASK_TRACED);
1972 
1973 	current->last_siginfo = info;
1974 	current->exit_code = exit_code;
1975 
1976 	/*
1977 	 * If @why is CLD_STOPPED, we're trapping to participate in a group
1978 	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1979 	 * across siglock relocks since INTERRUPT was scheduled, PENDING
1980 	 * could be clear now.  We act as if SIGCONT is received after
1981 	 * TASK_TRACED is entered - ignore it.
1982 	 */
1983 	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1984 		gstop_done = task_participate_group_stop(current);
1985 
1986 	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1987 	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1988 	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1989 		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1990 
1991 	/* entering a trap, clear TRAPPING */
1992 	task_clear_jobctl_trapping(current);
1993 
1994 	spin_unlock_irq(&current->sighand->siglock);
1995 	read_lock(&tasklist_lock);
1996 	if (may_ptrace_stop()) {
1997 		/*
1998 		 * Notify parents of the stop.
1999 		 *
2000 		 * While ptraced, there are two parents - the ptracer and
2001 		 * the real_parent of the group_leader.  The ptracer should
2002 		 * know about every stop while the real parent is only
2003 		 * interested in the completion of group stop.  The states
2004 		 * for the two don't interact with each other.  Notify
2005 		 * separately unless they're gonna be duplicates.
2006 		 */
2007 		do_notify_parent_cldstop(current, true, why);
2008 		if (gstop_done && ptrace_reparented(current))
2009 			do_notify_parent_cldstop(current, false, why);
2010 
2011 		/*
2012 		 * Don't want to allow preemption here, because
2013 		 * sys_ptrace() needs this task to be inactive.
2014 		 *
2015 		 * XXX: implement read_unlock_no_resched().
2016 		 */
2017 		preempt_disable();
2018 		read_unlock(&tasklist_lock);
2019 		preempt_enable_no_resched();
2020 		freezable_schedule();
2021 	} else {
2022 		/*
2023 		 * By the time we got the lock, our tracer went away.
2024 		 * Don't drop the lock yet, another tracer may come.
2025 		 *
2026 		 * If @gstop_done, the ptracer went away between group stop
2027 		 * completion and here.  During detach, it would have set
2028 		 * JOBCTL_STOP_PENDING on us and we'll re-enter
2029 		 * TASK_STOPPED in do_signal_stop() on return, so notifying
2030 		 * the real parent of the group stop completion is enough.
2031 		 */
2032 		if (gstop_done)
2033 			do_notify_parent_cldstop(current, false, why);
2034 
2035 		/* tasklist protects us from ptrace_freeze_traced() */
2036 		__set_current_state(TASK_RUNNING);
2037 		if (clear_code)
2038 			current->exit_code = 0;
2039 		read_unlock(&tasklist_lock);
2040 	}
2041 
2042 	/*
2043 	 * We are back.  Now reacquire the siglock before touching
2044 	 * last_siginfo, so that we are sure to have synchronized with
2045 	 * any signal-sending on another CPU that wants to examine it.
2046 	 */
2047 	spin_lock_irq(&current->sighand->siglock);
2048 	current->last_siginfo = NULL;
2049 
2050 	/* LISTENING can be set only during STOP traps, clear it */
2051 	current->jobctl &= ~JOBCTL_LISTENING;
2052 
2053 	/*
2054 	 * Queued signals ignored us while we were stopped for tracing.
2055 	 * So check for any that we should take before resuming user mode.
2056 	 * This sets TIF_SIGPENDING, but never clears it.
2057 	 */
2058 	recalc_sigpending_tsk(current);
2059 }
2060 
2061 static void ptrace_do_notify(int signr, int exit_code, int why)
2062 {
2063 	siginfo_t info;
2064 
2065 	clear_siginfo(&info);
2066 	info.si_signo = signr;
2067 	info.si_code = exit_code;
2068 	info.si_pid = task_pid_vnr(current);
2069 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2070 
2071 	/* Let the debugger run.  */
2072 	ptrace_stop(exit_code, why, 1, &info);
2073 }
2074 
2075 void ptrace_notify(int exit_code)
2076 {
2077 	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2078 	if (unlikely(current->task_works))
2079 		task_work_run();
2080 
2081 	spin_lock_irq(&current->sighand->siglock);
2082 	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2083 	spin_unlock_irq(&current->sighand->siglock);
2084 }
2085 
2086 /**
2087  * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2088  * @signr: signr causing group stop if initiating
2089  *
2090  * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2091  * and participate in it.  If already set, participate in the existing
2092  * group stop.  If participated in a group stop (and thus slept), %true is
2093  * returned with siglock released.
2094  *
2095  * If ptraced, this function doesn't handle stop itself.  Instead,
2096  * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2097  * untouched.  The caller must ensure that INTERRUPT trap handling takes
2098  * places afterwards.
2099  *
2100  * CONTEXT:
2101  * Must be called with @current->sighand->siglock held, which is released
2102  * on %true return.
2103  *
2104  * RETURNS:
2105  * %false if group stop is already cancelled or ptrace trap is scheduled.
2106  * %true if participated in group stop.
2107  */
2108 static bool do_signal_stop(int signr)
2109 	__releases(&current->sighand->siglock)
2110 {
2111 	struct signal_struct *sig = current->signal;
2112 
2113 	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2114 		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2115 		struct task_struct *t;
2116 
2117 		/* signr will be recorded in task->jobctl for retries */
2118 		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2119 
2120 		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2121 		    unlikely(signal_group_exit(sig)))
2122 			return false;
2123 		/*
2124 		 * There is no group stop already in progress.  We must
2125 		 * initiate one now.
2126 		 *
2127 		 * While ptraced, a task may be resumed while group stop is
2128 		 * still in effect and then receive a stop signal and
2129 		 * initiate another group stop.  This deviates from the
2130 		 * usual behavior as two consecutive stop signals can't
2131 		 * cause two group stops when !ptraced.  That is why we
2132 		 * also check !task_is_stopped(t) below.
2133 		 *
2134 		 * The condition can be distinguished by testing whether
2135 		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
2136 		 * group_exit_code in such case.
2137 		 *
2138 		 * This is not necessary for SIGNAL_STOP_CONTINUED because
2139 		 * an intervening stop signal is required to cause two
2140 		 * continued events regardless of ptrace.
2141 		 */
2142 		if (!(sig->flags & SIGNAL_STOP_STOPPED))
2143 			sig->group_exit_code = signr;
2144 
2145 		sig->group_stop_count = 0;
2146 
2147 		if (task_set_jobctl_pending(current, signr | gstop))
2148 			sig->group_stop_count++;
2149 
2150 		t = current;
2151 		while_each_thread(current, t) {
2152 			/*
2153 			 * Setting state to TASK_STOPPED for a group
2154 			 * stop is always done with the siglock held,
2155 			 * so this check has no races.
2156 			 */
2157 			if (!task_is_stopped(t) &&
2158 			    task_set_jobctl_pending(t, signr | gstop)) {
2159 				sig->group_stop_count++;
2160 				if (likely(!(t->ptrace & PT_SEIZED)))
2161 					signal_wake_up(t, 0);
2162 				else
2163 					ptrace_trap_notify(t);
2164 			}
2165 		}
2166 	}
2167 
2168 	if (likely(!current->ptrace)) {
2169 		int notify = 0;
2170 
2171 		/*
2172 		 * If there are no other threads in the group, or if there
2173 		 * is a group stop in progress and we are the last to stop,
2174 		 * report to the parent.
2175 		 */
2176 		if (task_participate_group_stop(current))
2177 			notify = CLD_STOPPED;
2178 
2179 		__set_current_state(TASK_STOPPED);
2180 		spin_unlock_irq(&current->sighand->siglock);
2181 
2182 		/*
2183 		 * Notify the parent of the group stop completion.  Because
2184 		 * we're not holding either the siglock or tasklist_lock
2185 		 * here, ptracer may attach inbetween; however, this is for
2186 		 * group stop and should always be delivered to the real
2187 		 * parent of the group leader.  The new ptracer will get
2188 		 * its notification when this task transitions into
2189 		 * TASK_TRACED.
2190 		 */
2191 		if (notify) {
2192 			read_lock(&tasklist_lock);
2193 			do_notify_parent_cldstop(current, false, notify);
2194 			read_unlock(&tasklist_lock);
2195 		}
2196 
2197 		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2198 		freezable_schedule();
2199 		return true;
2200 	} else {
2201 		/*
2202 		 * While ptraced, group stop is handled by STOP trap.
2203 		 * Schedule it and let the caller deal with it.
2204 		 */
2205 		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2206 		return false;
2207 	}
2208 }
2209 
2210 /**
2211  * do_jobctl_trap - take care of ptrace jobctl traps
2212  *
2213  * When PT_SEIZED, it's used for both group stop and explicit
2214  * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
2215  * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
2216  * the stop signal; otherwise, %SIGTRAP.
2217  *
2218  * When !PT_SEIZED, it's used only for group stop trap with stop signal
2219  * number as exit_code and no siginfo.
2220  *
2221  * CONTEXT:
2222  * Must be called with @current->sighand->siglock held, which may be
2223  * released and re-acquired before returning with intervening sleep.
2224  */
2225 static void do_jobctl_trap(void)
2226 {
2227 	struct signal_struct *signal = current->signal;
2228 	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2229 
2230 	if (current->ptrace & PT_SEIZED) {
2231 		if (!signal->group_stop_count &&
2232 		    !(signal->flags & SIGNAL_STOP_STOPPED))
2233 			signr = SIGTRAP;
2234 		WARN_ON_ONCE(!signr);
2235 		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2236 				 CLD_STOPPED);
2237 	} else {
2238 		WARN_ON_ONCE(!signr);
2239 		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2240 		current->exit_code = 0;
2241 	}
2242 }
2243 
2244 static int ptrace_signal(int signr, siginfo_t *info)
2245 {
2246 	/*
2247 	 * We do not check sig_kernel_stop(signr) but set this marker
2248 	 * unconditionally because we do not know whether debugger will
2249 	 * change signr. This flag has no meaning unless we are going
2250 	 * to stop after return from ptrace_stop(). In this case it will
2251 	 * be checked in do_signal_stop(), we should only stop if it was
2252 	 * not cleared by SIGCONT while we were sleeping. See also the
2253 	 * comment in dequeue_signal().
2254 	 */
2255 	current->jobctl |= JOBCTL_STOP_DEQUEUED;
2256 	ptrace_stop(signr, CLD_TRAPPED, 0, info);
2257 
2258 	/* We're back.  Did the debugger cancel the sig?  */
2259 	signr = current->exit_code;
2260 	if (signr == 0)
2261 		return signr;
2262 
2263 	current->exit_code = 0;
2264 
2265 	/*
2266 	 * Update the siginfo structure if the signal has
2267 	 * changed.  If the debugger wanted something
2268 	 * specific in the siginfo structure then it should
2269 	 * have updated *info via PTRACE_SETSIGINFO.
2270 	 */
2271 	if (signr != info->si_signo) {
2272 		clear_siginfo(info);
2273 		info->si_signo = signr;
2274 		info->si_errno = 0;
2275 		info->si_code = SI_USER;
2276 		rcu_read_lock();
2277 		info->si_pid = task_pid_vnr(current->parent);
2278 		info->si_uid = from_kuid_munged(current_user_ns(),
2279 						task_uid(current->parent));
2280 		rcu_read_unlock();
2281 	}
2282 
2283 	/* If the (new) signal is now blocked, requeue it.  */
2284 	if (sigismember(&current->blocked, signr)) {
2285 		specific_send_sig_info(signr, info, current);
2286 		signr = 0;
2287 	}
2288 
2289 	return signr;
2290 }
2291 
2292 int get_signal(struct ksignal *ksig)
2293 {
2294 	struct sighand_struct *sighand = current->sighand;
2295 	struct signal_struct *signal = current->signal;
2296 	int signr;
2297 
2298 	if (unlikely(current->task_works))
2299 		task_work_run();
2300 
2301 	if (unlikely(uprobe_deny_signal()))
2302 		return 0;
2303 
2304 	/*
2305 	 * Do this once, we can't return to user-mode if freezing() == T.
2306 	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2307 	 * thus do not need another check after return.
2308 	 */
2309 	try_to_freeze();
2310 
2311 relock:
2312 	spin_lock_irq(&sighand->siglock);
2313 	/*
2314 	 * Every stopped thread goes here after wakeup. Check to see if
2315 	 * we should notify the parent, prepare_signal(SIGCONT) encodes
2316 	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2317 	 */
2318 	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2319 		int why;
2320 
2321 		if (signal->flags & SIGNAL_CLD_CONTINUED)
2322 			why = CLD_CONTINUED;
2323 		else
2324 			why = CLD_STOPPED;
2325 
2326 		signal->flags &= ~SIGNAL_CLD_MASK;
2327 
2328 		spin_unlock_irq(&sighand->siglock);
2329 
2330 		/*
2331 		 * Notify the parent that we're continuing.  This event is
2332 		 * always per-process and doesn't make whole lot of sense
2333 		 * for ptracers, who shouldn't consume the state via
2334 		 * wait(2) either, but, for backward compatibility, notify
2335 		 * the ptracer of the group leader too unless it's gonna be
2336 		 * a duplicate.
2337 		 */
2338 		read_lock(&tasklist_lock);
2339 		do_notify_parent_cldstop(current, false, why);
2340 
2341 		if (ptrace_reparented(current->group_leader))
2342 			do_notify_parent_cldstop(current->group_leader,
2343 						true, why);
2344 		read_unlock(&tasklist_lock);
2345 
2346 		goto relock;
2347 	}
2348 
2349 	for (;;) {
2350 		struct k_sigaction *ka;
2351 
2352 		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2353 		    do_signal_stop(0))
2354 			goto relock;
2355 
2356 		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2357 			do_jobctl_trap();
2358 			spin_unlock_irq(&sighand->siglock);
2359 			goto relock;
2360 		}
2361 
2362 		signr = dequeue_signal(current, &current->blocked, &ksig->info);
2363 
2364 		if (!signr)
2365 			break; /* will return 0 */
2366 
2367 		if (unlikely(current->ptrace) && signr != SIGKILL) {
2368 			signr = ptrace_signal(signr, &ksig->info);
2369 			if (!signr)
2370 				continue;
2371 		}
2372 
2373 		ka = &sighand->action[signr-1];
2374 
2375 		/* Trace actually delivered signals. */
2376 		trace_signal_deliver(signr, &ksig->info, ka);
2377 
2378 		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
2379 			continue;
2380 		if (ka->sa.sa_handler != SIG_DFL) {
2381 			/* Run the handler.  */
2382 			ksig->ka = *ka;
2383 
2384 			if (ka->sa.sa_flags & SA_ONESHOT)
2385 				ka->sa.sa_handler = SIG_DFL;
2386 
2387 			break; /* will return non-zero "signr" value */
2388 		}
2389 
2390 		/*
2391 		 * Now we are doing the default action for this signal.
2392 		 */
2393 		if (sig_kernel_ignore(signr)) /* Default is nothing. */
2394 			continue;
2395 
2396 		/*
2397 		 * Global init gets no signals it doesn't want.
2398 		 * Container-init gets no signals it doesn't want from same
2399 		 * container.
2400 		 *
2401 		 * Note that if global/container-init sees a sig_kernel_only()
2402 		 * signal here, the signal must have been generated internally
2403 		 * or must have come from an ancestor namespace. In either
2404 		 * case, the signal cannot be dropped.
2405 		 */
2406 		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2407 				!sig_kernel_only(signr))
2408 			continue;
2409 
2410 		if (sig_kernel_stop(signr)) {
2411 			/*
2412 			 * The default action is to stop all threads in
2413 			 * the thread group.  The job control signals
2414 			 * do nothing in an orphaned pgrp, but SIGSTOP
2415 			 * always works.  Note that siglock needs to be
2416 			 * dropped during the call to is_orphaned_pgrp()
2417 			 * because of lock ordering with tasklist_lock.
2418 			 * This allows an intervening SIGCONT to be posted.
2419 			 * We need to check for that and bail out if necessary.
2420 			 */
2421 			if (signr != SIGSTOP) {
2422 				spin_unlock_irq(&sighand->siglock);
2423 
2424 				/* signals can be posted during this window */
2425 
2426 				if (is_current_pgrp_orphaned())
2427 					goto relock;
2428 
2429 				spin_lock_irq(&sighand->siglock);
2430 			}
2431 
2432 			if (likely(do_signal_stop(ksig->info.si_signo))) {
2433 				/* It released the siglock.  */
2434 				goto relock;
2435 			}
2436 
2437 			/*
2438 			 * We didn't actually stop, due to a race
2439 			 * with SIGCONT or something like that.
2440 			 */
2441 			continue;
2442 		}
2443 
2444 		spin_unlock_irq(&sighand->siglock);
2445 
2446 		/*
2447 		 * Anything else is fatal, maybe with a core dump.
2448 		 */
2449 		current->flags |= PF_SIGNALED;
2450 
2451 		if (sig_kernel_coredump(signr)) {
2452 			if (print_fatal_signals)
2453 				print_fatal_signal(ksig->info.si_signo);
2454 			proc_coredump_connector(current);
2455 			/*
2456 			 * If it was able to dump core, this kills all
2457 			 * other threads in the group and synchronizes with
2458 			 * their demise.  If we lost the race with another
2459 			 * thread getting here, it set group_exit_code
2460 			 * first and our do_group_exit call below will use
2461 			 * that value and ignore the one we pass it.
2462 			 */
2463 			do_coredump(&ksig->info);
2464 		}
2465 
2466 		/*
2467 		 * Death signals, no core dump.
2468 		 */
2469 		do_group_exit(ksig->info.si_signo);
2470 		/* NOTREACHED */
2471 	}
2472 	spin_unlock_irq(&sighand->siglock);
2473 
2474 	ksig->sig = signr;
2475 	return ksig->sig > 0;
2476 }
2477 
2478 /**
2479  * signal_delivered -
2480  * @ksig:		kernel signal struct
2481  * @stepping:		nonzero if debugger single-step or block-step in use
2482  *
2483  * This function should be called when a signal has successfully been
2484  * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2485  * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2486  * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2487  */
2488 static void signal_delivered(struct ksignal *ksig, int stepping)
2489 {
2490 	sigset_t blocked;
2491 
2492 	/* A signal was successfully delivered, and the
2493 	   saved sigmask was stored on the signal frame,
2494 	   and will be restored by sigreturn.  So we can
2495 	   simply clear the restore sigmask flag.  */
2496 	clear_restore_sigmask();
2497 
2498 	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
2499 	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2500 		sigaddset(&blocked, ksig->sig);
2501 	set_current_blocked(&blocked);
2502 	tracehook_signal_handler(stepping);
2503 }
2504 
2505 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2506 {
2507 	if (failed)
2508 		force_sigsegv(ksig->sig, current);
2509 	else
2510 		signal_delivered(ksig, stepping);
2511 }
2512 
2513 /*
2514  * It could be that complete_signal() picked us to notify about the
2515  * group-wide signal. Other threads should be notified now to take
2516  * the shared signals in @which since we will not.
2517  */
2518 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2519 {
2520 	sigset_t retarget;
2521 	struct task_struct *t;
2522 
2523 	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2524 	if (sigisemptyset(&retarget))
2525 		return;
2526 
2527 	t = tsk;
2528 	while_each_thread(tsk, t) {
2529 		if (t->flags & PF_EXITING)
2530 			continue;
2531 
2532 		if (!has_pending_signals(&retarget, &t->blocked))
2533 			continue;
2534 		/* Remove the signals this thread can handle. */
2535 		sigandsets(&retarget, &retarget, &t->blocked);
2536 
2537 		if (!signal_pending(t))
2538 			signal_wake_up(t, 0);
2539 
2540 		if (sigisemptyset(&retarget))
2541 			break;
2542 	}
2543 }
2544 
2545 void exit_signals(struct task_struct *tsk)
2546 {
2547 	int group_stop = 0;
2548 	sigset_t unblocked;
2549 
2550 	/*
2551 	 * @tsk is about to have PF_EXITING set - lock out users which
2552 	 * expect stable threadgroup.
2553 	 */
2554 	cgroup_threadgroup_change_begin(tsk);
2555 
2556 	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2557 		tsk->flags |= PF_EXITING;
2558 		cgroup_threadgroup_change_end(tsk);
2559 		return;
2560 	}
2561 
2562 	spin_lock_irq(&tsk->sighand->siglock);
2563 	/*
2564 	 * From now this task is not visible for group-wide signals,
2565 	 * see wants_signal(), do_signal_stop().
2566 	 */
2567 	tsk->flags |= PF_EXITING;
2568 
2569 	cgroup_threadgroup_change_end(tsk);
2570 
2571 	if (!signal_pending(tsk))
2572 		goto out;
2573 
2574 	unblocked = tsk->blocked;
2575 	signotset(&unblocked);
2576 	retarget_shared_pending(tsk, &unblocked);
2577 
2578 	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2579 	    task_participate_group_stop(tsk))
2580 		group_stop = CLD_STOPPED;
2581 out:
2582 	spin_unlock_irq(&tsk->sighand->siglock);
2583 
2584 	/*
2585 	 * If group stop has completed, deliver the notification.  This
2586 	 * should always go to the real parent of the group leader.
2587 	 */
2588 	if (unlikely(group_stop)) {
2589 		read_lock(&tasklist_lock);
2590 		do_notify_parent_cldstop(tsk, false, group_stop);
2591 		read_unlock(&tasklist_lock);
2592 	}
2593 }
2594 
2595 EXPORT_SYMBOL(recalc_sigpending);
2596 EXPORT_SYMBOL_GPL(dequeue_signal);
2597 EXPORT_SYMBOL(flush_signals);
2598 EXPORT_SYMBOL(force_sig);
2599 EXPORT_SYMBOL(send_sig);
2600 EXPORT_SYMBOL(send_sig_info);
2601 EXPORT_SYMBOL(sigprocmask);
2602 
2603 /*
2604  * System call entry points.
2605  */
2606 
2607 /**
2608  *  sys_restart_syscall - restart a system call
2609  */
2610 SYSCALL_DEFINE0(restart_syscall)
2611 {
2612 	struct restart_block *restart = &current->restart_block;
2613 	return restart->fn(restart);
2614 }
2615 
2616 long do_no_restart_syscall(struct restart_block *param)
2617 {
2618 	return -EINTR;
2619 }
2620 
2621 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2622 {
2623 	if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2624 		sigset_t newblocked;
2625 		/* A set of now blocked but previously unblocked signals. */
2626 		sigandnsets(&newblocked, newset, &current->blocked);
2627 		retarget_shared_pending(tsk, &newblocked);
2628 	}
2629 	tsk->blocked = *newset;
2630 	recalc_sigpending();
2631 }
2632 
2633 /**
2634  * set_current_blocked - change current->blocked mask
2635  * @newset: new mask
2636  *
2637  * It is wrong to change ->blocked directly, this helper should be used
2638  * to ensure the process can't miss a shared signal we are going to block.
2639  */
2640 void set_current_blocked(sigset_t *newset)
2641 {
2642 	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2643 	__set_current_blocked(newset);
2644 }
2645 
2646 void __set_current_blocked(const sigset_t *newset)
2647 {
2648 	struct task_struct *tsk = current;
2649 
2650 	/*
2651 	 * In case the signal mask hasn't changed, there is nothing we need
2652 	 * to do. The current->blocked shouldn't be modified by other task.
2653 	 */
2654 	if (sigequalsets(&tsk->blocked, newset))
2655 		return;
2656 
2657 	spin_lock_irq(&tsk->sighand->siglock);
2658 	__set_task_blocked(tsk, newset);
2659 	spin_unlock_irq(&tsk->sighand->siglock);
2660 }
2661 
2662 /*
2663  * This is also useful for kernel threads that want to temporarily
2664  * (or permanently) block certain signals.
2665  *
2666  * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2667  * interface happily blocks "unblockable" signals like SIGKILL
2668  * and friends.
2669  */
2670 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2671 {
2672 	struct task_struct *tsk = current;
2673 	sigset_t newset;
2674 
2675 	/* Lockless, only current can change ->blocked, never from irq */
2676 	if (oldset)
2677 		*oldset = tsk->blocked;
2678 
2679 	switch (how) {
2680 	case SIG_BLOCK:
2681 		sigorsets(&newset, &tsk->blocked, set);
2682 		break;
2683 	case SIG_UNBLOCK:
2684 		sigandnsets(&newset, &tsk->blocked, set);
2685 		break;
2686 	case SIG_SETMASK:
2687 		newset = *set;
2688 		break;
2689 	default:
2690 		return -EINVAL;
2691 	}
2692 
2693 	__set_current_blocked(&newset);
2694 	return 0;
2695 }
2696 
2697 /**
2698  *  sys_rt_sigprocmask - change the list of currently blocked signals
2699  *  @how: whether to add, remove, or set signals
2700  *  @nset: stores pending signals
2701  *  @oset: previous value of signal mask if non-null
2702  *  @sigsetsize: size of sigset_t type
2703  */
2704 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2705 		sigset_t __user *, oset, size_t, sigsetsize)
2706 {
2707 	sigset_t old_set, new_set;
2708 	int error;
2709 
2710 	/* XXX: Don't preclude handling different sized sigset_t's.  */
2711 	if (sigsetsize != sizeof(sigset_t))
2712 		return -EINVAL;
2713 
2714 	old_set = current->blocked;
2715 
2716 	if (nset) {
2717 		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2718 			return -EFAULT;
2719 		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2720 
2721 		error = sigprocmask(how, &new_set, NULL);
2722 		if (error)
2723 			return error;
2724 	}
2725 
2726 	if (oset) {
2727 		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2728 			return -EFAULT;
2729 	}
2730 
2731 	return 0;
2732 }
2733 
2734 #ifdef CONFIG_COMPAT
2735 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2736 		compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2737 {
2738 	sigset_t old_set = current->blocked;
2739 
2740 	/* XXX: Don't preclude handling different sized sigset_t's.  */
2741 	if (sigsetsize != sizeof(sigset_t))
2742 		return -EINVAL;
2743 
2744 	if (nset) {
2745 		sigset_t new_set;
2746 		int error;
2747 		if (get_compat_sigset(&new_set, nset))
2748 			return -EFAULT;
2749 		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2750 
2751 		error = sigprocmask(how, &new_set, NULL);
2752 		if (error)
2753 			return error;
2754 	}
2755 	return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
2756 }
2757 #endif
2758 
2759 static int do_sigpending(sigset_t *set)
2760 {
2761 	spin_lock_irq(&current->sighand->siglock);
2762 	sigorsets(set, &current->pending.signal,
2763 		  &current->signal->shared_pending.signal);
2764 	spin_unlock_irq(&current->sighand->siglock);
2765 
2766 	/* Outside the lock because only this thread touches it.  */
2767 	sigandsets(set, &current->blocked, set);
2768 	return 0;
2769 }
2770 
2771 /**
2772  *  sys_rt_sigpending - examine a pending signal that has been raised
2773  *			while blocked
2774  *  @uset: stores pending signals
2775  *  @sigsetsize: size of sigset_t type or larger
2776  */
2777 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2778 {
2779 	sigset_t set;
2780 	int err;
2781 
2782 	if (sigsetsize > sizeof(*uset))
2783 		return -EINVAL;
2784 
2785 	err = do_sigpending(&set);
2786 	if (!err && copy_to_user(uset, &set, sigsetsize))
2787 		err = -EFAULT;
2788 	return err;
2789 }
2790 
2791 #ifdef CONFIG_COMPAT
2792 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2793 		compat_size_t, sigsetsize)
2794 {
2795 	sigset_t set;
2796 	int err;
2797 
2798 	if (sigsetsize > sizeof(*uset))
2799 		return -EINVAL;
2800 
2801 	err = do_sigpending(&set);
2802 	if (!err)
2803 		err = put_compat_sigset(uset, &set, sigsetsize);
2804 	return err;
2805 }
2806 #endif
2807 
2808 enum siginfo_layout siginfo_layout(int sig, int si_code)
2809 {
2810 	enum siginfo_layout layout = SIL_KILL;
2811 	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
2812 		static const struct {
2813 			unsigned char limit, layout;
2814 		} filter[] = {
2815 			[SIGILL]  = { NSIGILL,  SIL_FAULT },
2816 			[SIGFPE]  = { NSIGFPE,  SIL_FAULT },
2817 			[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
2818 			[SIGBUS]  = { NSIGBUS,  SIL_FAULT },
2819 			[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
2820 #if defined(SIGEMT) && defined(NSIGEMT)
2821 			[SIGEMT]  = { NSIGEMT,  SIL_FAULT },
2822 #endif
2823 			[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
2824 			[SIGPOLL] = { NSIGPOLL, SIL_POLL },
2825 			[SIGSYS]  = { NSIGSYS,  SIL_SYS },
2826 		};
2827 		if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit))
2828 			layout = filter[sig].layout;
2829 		else if (si_code <= NSIGPOLL)
2830 			layout = SIL_POLL;
2831 	} else {
2832 		if (si_code == SI_TIMER)
2833 			layout = SIL_TIMER;
2834 		else if (si_code == SI_SIGIO)
2835 			layout = SIL_POLL;
2836 		else if (si_code < 0)
2837 			layout = SIL_RT;
2838 		/* Tests to support buggy kernel ABIs */
2839 #ifdef TRAP_FIXME
2840 		if ((sig == SIGTRAP) && (si_code == TRAP_FIXME))
2841 			layout = SIL_FAULT;
2842 #endif
2843 #ifdef FPE_FIXME
2844 		if ((sig == SIGFPE) && (si_code == FPE_FIXME))
2845 			layout = SIL_FAULT;
2846 #endif
2847 	}
2848 	return layout;
2849 }
2850 
2851 int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2852 {
2853 	int err;
2854 
2855 	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2856 		return -EFAULT;
2857 	if (from->si_code < 0)
2858 		return __copy_to_user(to, from, sizeof(siginfo_t))
2859 			? -EFAULT : 0;
2860 	/*
2861 	 * If you change siginfo_t structure, please be sure
2862 	 * this code is fixed accordingly.
2863 	 * Please remember to update the signalfd_copyinfo() function
2864 	 * inside fs/signalfd.c too, in case siginfo_t changes.
2865 	 * It should never copy any pad contained in the structure
2866 	 * to avoid security leaks, but must copy the generic
2867 	 * 3 ints plus the relevant union member.
2868 	 */
2869 	err = __put_user(from->si_signo, &to->si_signo);
2870 	err |= __put_user(from->si_errno, &to->si_errno);
2871 	err |= __put_user(from->si_code, &to->si_code);
2872 	switch (siginfo_layout(from->si_signo, from->si_code)) {
2873 	case SIL_KILL:
2874 		err |= __put_user(from->si_pid, &to->si_pid);
2875 		err |= __put_user(from->si_uid, &to->si_uid);
2876 		break;
2877 	case SIL_TIMER:
2878 		/* Unreached SI_TIMER is negative */
2879 		break;
2880 	case SIL_POLL:
2881 		err |= __put_user(from->si_band, &to->si_band);
2882 		err |= __put_user(from->si_fd, &to->si_fd);
2883 		break;
2884 	case SIL_FAULT:
2885 		err |= __put_user(from->si_addr, &to->si_addr);
2886 #ifdef __ARCH_SI_TRAPNO
2887 		err |= __put_user(from->si_trapno, &to->si_trapno);
2888 #endif
2889 #ifdef __ia64__
2890 		err |= __put_user(from->si_imm, &to->si_imm);
2891 		err |= __put_user(from->si_flags, &to->si_flags);
2892 		err |= __put_user(from->si_isr, &to->si_isr);
2893 #endif
2894 		/*
2895 		 * Other callers might not initialize the si_lsb field,
2896 		 * so check explicitly for the right codes here.
2897 		 */
2898 #ifdef BUS_MCEERR_AR
2899 		if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AR)
2900 			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2901 #endif
2902 #ifdef BUS_MCEERR_AO
2903 		if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AO)
2904 			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2905 #endif
2906 #ifdef SEGV_BNDERR
2907 		if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2908 			err |= __put_user(from->si_lower, &to->si_lower);
2909 			err |= __put_user(from->si_upper, &to->si_upper);
2910 		}
2911 #endif
2912 #ifdef SEGV_PKUERR
2913 		if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2914 			err |= __put_user(from->si_pkey, &to->si_pkey);
2915 #endif
2916 		break;
2917 	case SIL_CHLD:
2918 		err |= __put_user(from->si_pid, &to->si_pid);
2919 		err |= __put_user(from->si_uid, &to->si_uid);
2920 		err |= __put_user(from->si_status, &to->si_status);
2921 		err |= __put_user(from->si_utime, &to->si_utime);
2922 		err |= __put_user(from->si_stime, &to->si_stime);
2923 		break;
2924 	case SIL_RT:
2925 		err |= __put_user(from->si_pid, &to->si_pid);
2926 		err |= __put_user(from->si_uid, &to->si_uid);
2927 		err |= __put_user(from->si_ptr, &to->si_ptr);
2928 		break;
2929 	case SIL_SYS:
2930 		err |= __put_user(from->si_call_addr, &to->si_call_addr);
2931 		err |= __put_user(from->si_syscall, &to->si_syscall);
2932 		err |= __put_user(from->si_arch, &to->si_arch);
2933 		break;
2934 	}
2935 	return err;
2936 }
2937 
2938 #ifdef CONFIG_COMPAT
2939 int copy_siginfo_to_user32(struct compat_siginfo __user *to,
2940 			   const struct siginfo *from)
2941 #if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
2942 {
2943 	return __copy_siginfo_to_user32(to, from, in_x32_syscall());
2944 }
2945 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
2946 			     const struct siginfo *from, bool x32_ABI)
2947 #endif
2948 {
2949 	struct compat_siginfo new;
2950 	memset(&new, 0, sizeof(new));
2951 
2952 	new.si_signo = from->si_signo;
2953 	new.si_errno = from->si_errno;
2954 	new.si_code  = from->si_code;
2955 	switch(siginfo_layout(from->si_signo, from->si_code)) {
2956 	case SIL_KILL:
2957 		new.si_pid = from->si_pid;
2958 		new.si_uid = from->si_uid;
2959 		break;
2960 	case SIL_TIMER:
2961 		new.si_tid     = from->si_tid;
2962 		new.si_overrun = from->si_overrun;
2963 		new.si_int     = from->si_int;
2964 		break;
2965 	case SIL_POLL:
2966 		new.si_band = from->si_band;
2967 		new.si_fd   = from->si_fd;
2968 		break;
2969 	case SIL_FAULT:
2970 		new.si_addr = ptr_to_compat(from->si_addr);
2971 #ifdef __ARCH_SI_TRAPNO
2972 		new.si_trapno = from->si_trapno;
2973 #endif
2974 #ifdef BUS_MCEERR_AR
2975 		if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AR))
2976 			new.si_addr_lsb = from->si_addr_lsb;
2977 #endif
2978 #ifdef BUS_MCEERR_AO
2979 		if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AO))
2980 			new.si_addr_lsb = from->si_addr_lsb;
2981 #endif
2982 #ifdef SEGV_BNDERR
2983 		if ((from->si_signo == SIGSEGV) &&
2984 		    (from->si_code == SEGV_BNDERR)) {
2985 			new.si_lower = ptr_to_compat(from->si_lower);
2986 			new.si_upper = ptr_to_compat(from->si_upper);
2987 		}
2988 #endif
2989 #ifdef SEGV_PKUERR
2990 		if ((from->si_signo == SIGSEGV) &&
2991 		    (from->si_code == SEGV_PKUERR))
2992 			new.si_pkey = from->si_pkey;
2993 #endif
2994 
2995 		break;
2996 	case SIL_CHLD:
2997 		new.si_pid    = from->si_pid;
2998 		new.si_uid    = from->si_uid;
2999 		new.si_status = from->si_status;
3000 #ifdef CONFIG_X86_X32_ABI
3001 		if (x32_ABI) {
3002 			new._sifields._sigchld_x32._utime = from->si_utime;
3003 			new._sifields._sigchld_x32._stime = from->si_stime;
3004 		} else
3005 #endif
3006 		{
3007 			new.si_utime = from->si_utime;
3008 			new.si_stime = from->si_stime;
3009 		}
3010 		break;
3011 	case SIL_RT:
3012 		new.si_pid = from->si_pid;
3013 		new.si_uid = from->si_uid;
3014 		new.si_int = from->si_int;
3015 		break;
3016 	case SIL_SYS:
3017 		new.si_call_addr = ptr_to_compat(from->si_call_addr);
3018 		new.si_syscall   = from->si_syscall;
3019 		new.si_arch      = from->si_arch;
3020 		break;
3021 	}
3022 
3023 	if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3024 		return -EFAULT;
3025 
3026 	return 0;
3027 }
3028 
3029 int copy_siginfo_from_user32(struct siginfo *to,
3030 			     const struct compat_siginfo __user *ufrom)
3031 {
3032 	struct compat_siginfo from;
3033 
3034 	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3035 		return -EFAULT;
3036 
3037 	clear_siginfo(to);
3038 	to->si_signo = from.si_signo;
3039 	to->si_errno = from.si_errno;
3040 	to->si_code  = from.si_code;
3041 	switch(siginfo_layout(from.si_signo, from.si_code)) {
3042 	case SIL_KILL:
3043 		to->si_pid = from.si_pid;
3044 		to->si_uid = from.si_uid;
3045 		break;
3046 	case SIL_TIMER:
3047 		to->si_tid     = from.si_tid;
3048 		to->si_overrun = from.si_overrun;
3049 		to->si_int     = from.si_int;
3050 		break;
3051 	case SIL_POLL:
3052 		to->si_band = from.si_band;
3053 		to->si_fd   = from.si_fd;
3054 		break;
3055 	case SIL_FAULT:
3056 		to->si_addr = compat_ptr(from.si_addr);
3057 #ifdef __ARCH_SI_TRAPNO
3058 		to->si_trapno = from.si_trapno;
3059 #endif
3060 #ifdef BUS_MCEERR_AR
3061 		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AR))
3062 			to->si_addr_lsb = from.si_addr_lsb;
3063 #endif
3064 #ifdef BUS_MCEER_AO
3065 		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AO))
3066 			to->si_addr_lsb = from.si_addr_lsb;
3067 #endif
3068 #ifdef SEGV_BNDERR
3069 		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) {
3070 			to->si_lower = compat_ptr(from.si_lower);
3071 			to->si_upper = compat_ptr(from.si_upper);
3072 		}
3073 #endif
3074 #ifdef SEGV_PKUERR
3075 		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR))
3076 			to->si_pkey = from.si_pkey;
3077 #endif
3078 		break;
3079 	case SIL_CHLD:
3080 		to->si_pid    = from.si_pid;
3081 		to->si_uid    = from.si_uid;
3082 		to->si_status = from.si_status;
3083 #ifdef CONFIG_X86_X32_ABI
3084 		if (in_x32_syscall()) {
3085 			to->si_utime = from._sifields._sigchld_x32._utime;
3086 			to->si_stime = from._sifields._sigchld_x32._stime;
3087 		} else
3088 #endif
3089 		{
3090 			to->si_utime = from.si_utime;
3091 			to->si_stime = from.si_stime;
3092 		}
3093 		break;
3094 	case SIL_RT:
3095 		to->si_pid = from.si_pid;
3096 		to->si_uid = from.si_uid;
3097 		to->si_int = from.si_int;
3098 		break;
3099 	case SIL_SYS:
3100 		to->si_call_addr = compat_ptr(from.si_call_addr);
3101 		to->si_syscall   = from.si_syscall;
3102 		to->si_arch      = from.si_arch;
3103 		break;
3104 	}
3105 	return 0;
3106 }
3107 #endif /* CONFIG_COMPAT */
3108 
3109 /**
3110  *  do_sigtimedwait - wait for queued signals specified in @which
3111  *  @which: queued signals to wait for
3112  *  @info: if non-null, the signal's siginfo is returned here
3113  *  @ts: upper bound on process time suspension
3114  */
3115 static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
3116 		    const struct timespec *ts)
3117 {
3118 	ktime_t *to = NULL, timeout = KTIME_MAX;
3119 	struct task_struct *tsk = current;
3120 	sigset_t mask = *which;
3121 	int sig, ret = 0;
3122 
3123 	if (ts) {
3124 		if (!timespec_valid(ts))
3125 			return -EINVAL;
3126 		timeout = timespec_to_ktime(*ts);
3127 		to = &timeout;
3128 	}
3129 
3130 	/*
3131 	 * Invert the set of allowed signals to get those we want to block.
3132 	 */
3133 	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3134 	signotset(&mask);
3135 
3136 	spin_lock_irq(&tsk->sighand->siglock);
3137 	sig = dequeue_signal(tsk, &mask, info);
3138 	if (!sig && timeout) {
3139 		/*
3140 		 * None ready, temporarily unblock those we're interested
3141 		 * while we are sleeping in so that we'll be awakened when
3142 		 * they arrive. Unblocking is always fine, we can avoid
3143 		 * set_current_blocked().
3144 		 */
3145 		tsk->real_blocked = tsk->blocked;
3146 		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3147 		recalc_sigpending();
3148 		spin_unlock_irq(&tsk->sighand->siglock);
3149 
3150 		__set_current_state(TASK_INTERRUPTIBLE);
3151 		ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3152 							 HRTIMER_MODE_REL);
3153 		spin_lock_irq(&tsk->sighand->siglock);
3154 		__set_task_blocked(tsk, &tsk->real_blocked);
3155 		sigemptyset(&tsk->real_blocked);
3156 		sig = dequeue_signal(tsk, &mask, info);
3157 	}
3158 	spin_unlock_irq(&tsk->sighand->siglock);
3159 
3160 	if (sig)
3161 		return sig;
3162 	return ret ? -EINTR : -EAGAIN;
3163 }
3164 
3165 /**
3166  *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
3167  *			in @uthese
3168  *  @uthese: queued signals to wait for
3169  *  @uinfo: if non-null, the signal's siginfo is returned here
3170  *  @uts: upper bound on process time suspension
3171  *  @sigsetsize: size of sigset_t type
3172  */
3173 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3174 		siginfo_t __user *, uinfo, const struct timespec __user *, uts,
3175 		size_t, sigsetsize)
3176 {
3177 	sigset_t these;
3178 	struct timespec ts;
3179 	siginfo_t info;
3180 	int ret;
3181 
3182 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3183 	if (sigsetsize != sizeof(sigset_t))
3184 		return -EINVAL;
3185 
3186 	if (copy_from_user(&these, uthese, sizeof(these)))
3187 		return -EFAULT;
3188 
3189 	if (uts) {
3190 		if (copy_from_user(&ts, uts, sizeof(ts)))
3191 			return -EFAULT;
3192 	}
3193 
3194 	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3195 
3196 	if (ret > 0 && uinfo) {
3197 		if (copy_siginfo_to_user(uinfo, &info))
3198 			ret = -EFAULT;
3199 	}
3200 
3201 	return ret;
3202 }
3203 
3204 #ifdef CONFIG_COMPAT
3205 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
3206 		struct compat_siginfo __user *, uinfo,
3207 		struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
3208 {
3209 	sigset_t s;
3210 	struct timespec t;
3211 	siginfo_t info;
3212 	long ret;
3213 
3214 	if (sigsetsize != sizeof(sigset_t))
3215 		return -EINVAL;
3216 
3217 	if (get_compat_sigset(&s, uthese))
3218 		return -EFAULT;
3219 
3220 	if (uts) {
3221 		if (compat_get_timespec(&t, uts))
3222 			return -EFAULT;
3223 	}
3224 
3225 	ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3226 
3227 	if (ret > 0 && uinfo) {
3228 		if (copy_siginfo_to_user32(uinfo, &info))
3229 			ret = -EFAULT;
3230 	}
3231 
3232 	return ret;
3233 }
3234 #endif
3235 
3236 /**
3237  *  sys_kill - send a signal to a process
3238  *  @pid: the PID of the process
3239  *  @sig: signal to be sent
3240  */
3241 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3242 {
3243 	struct siginfo info;
3244 
3245 	clear_siginfo(&info);
3246 	info.si_signo = sig;
3247 	info.si_errno = 0;
3248 	info.si_code = SI_USER;
3249 	info.si_pid = task_tgid_vnr(current);
3250 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3251 
3252 	return kill_something_info(sig, &info, pid);
3253 }
3254 
3255 static int
3256 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
3257 {
3258 	struct task_struct *p;
3259 	int error = -ESRCH;
3260 
3261 	rcu_read_lock();
3262 	p = find_task_by_vpid(pid);
3263 	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3264 		error = check_kill_permission(sig, info, p);
3265 		/*
3266 		 * The null signal is a permissions and process existence
3267 		 * probe.  No signal is actually delivered.
3268 		 */
3269 		if (!error && sig) {
3270 			error = do_send_sig_info(sig, info, p, false);
3271 			/*
3272 			 * If lock_task_sighand() failed we pretend the task
3273 			 * dies after receiving the signal. The window is tiny,
3274 			 * and the signal is private anyway.
3275 			 */
3276 			if (unlikely(error == -ESRCH))
3277 				error = 0;
3278 		}
3279 	}
3280 	rcu_read_unlock();
3281 
3282 	return error;
3283 }
3284 
3285 static int do_tkill(pid_t tgid, pid_t pid, int sig)
3286 {
3287 	struct siginfo info;
3288 
3289 	clear_siginfo(&info);
3290 	info.si_signo = sig;
3291 	info.si_errno = 0;
3292 	info.si_code = SI_TKILL;
3293 	info.si_pid = task_tgid_vnr(current);
3294 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3295 
3296 	return do_send_specific(tgid, pid, sig, &info);
3297 }
3298 
3299 /**
3300  *  sys_tgkill - send signal to one specific thread
3301  *  @tgid: the thread group ID of the thread
3302  *  @pid: the PID of the thread
3303  *  @sig: signal to be sent
3304  *
3305  *  This syscall also checks the @tgid and returns -ESRCH even if the PID
3306  *  exists but it's not belonging to the target process anymore. This
3307  *  method solves the problem of threads exiting and PIDs getting reused.
3308  */
3309 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3310 {
3311 	/* This is only valid for single tasks */
3312 	if (pid <= 0 || tgid <= 0)
3313 		return -EINVAL;
3314 
3315 	return do_tkill(tgid, pid, sig);
3316 }
3317 
3318 /**
3319  *  sys_tkill - send signal to one specific task
3320  *  @pid: the PID of the task
3321  *  @sig: signal to be sent
3322  *
3323  *  Send a signal to only one task, even if it's a CLONE_THREAD task.
3324  */
3325 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3326 {
3327 	/* This is only valid for single tasks */
3328 	if (pid <= 0)
3329 		return -EINVAL;
3330 
3331 	return do_tkill(0, pid, sig);
3332 }
3333 
3334 static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3335 {
3336 	/* Not even root can pretend to send signals from the kernel.
3337 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3338 	 */
3339 	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3340 	    (task_pid_vnr(current) != pid))
3341 		return -EPERM;
3342 
3343 	info->si_signo = sig;
3344 
3345 	/* POSIX.1b doesn't mention process groups.  */
3346 	return kill_proc_info(sig, info, pid);
3347 }
3348 
3349 /**
3350  *  sys_rt_sigqueueinfo - send signal information to a signal
3351  *  @pid: the PID of the thread
3352  *  @sig: signal to be sent
3353  *  @uinfo: signal info to be sent
3354  */
3355 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3356 		siginfo_t __user *, uinfo)
3357 {
3358 	siginfo_t info;
3359 	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3360 		return -EFAULT;
3361 	return do_rt_sigqueueinfo(pid, sig, &info);
3362 }
3363 
3364 #ifdef CONFIG_COMPAT
3365 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3366 			compat_pid_t, pid,
3367 			int, sig,
3368 			struct compat_siginfo __user *, uinfo)
3369 {
3370 	siginfo_t info;
3371 	int ret = copy_siginfo_from_user32(&info, uinfo);
3372 	if (unlikely(ret))
3373 		return ret;
3374 	return do_rt_sigqueueinfo(pid, sig, &info);
3375 }
3376 #endif
3377 
3378 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3379 {
3380 	/* This is only valid for single tasks */
3381 	if (pid <= 0 || tgid <= 0)
3382 		return -EINVAL;
3383 
3384 	/* Not even root can pretend to send signals from the kernel.
3385 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3386 	 */
3387 	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3388 	    (task_pid_vnr(current) != pid))
3389 		return -EPERM;
3390 
3391 	info->si_signo = sig;
3392 
3393 	return do_send_specific(tgid, pid, sig, info);
3394 }
3395 
3396 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3397 		siginfo_t __user *, uinfo)
3398 {
3399 	siginfo_t info;
3400 
3401 	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3402 		return -EFAULT;
3403 
3404 	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3405 }
3406 
3407 #ifdef CONFIG_COMPAT
3408 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3409 			compat_pid_t, tgid,
3410 			compat_pid_t, pid,
3411 			int, sig,
3412 			struct compat_siginfo __user *, uinfo)
3413 {
3414 	siginfo_t info;
3415 
3416 	if (copy_siginfo_from_user32(&info, uinfo))
3417 		return -EFAULT;
3418 	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3419 }
3420 #endif
3421 
3422 /*
3423  * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3424  */
3425 void kernel_sigaction(int sig, __sighandler_t action)
3426 {
3427 	spin_lock_irq(&current->sighand->siglock);
3428 	current->sighand->action[sig - 1].sa.sa_handler = action;
3429 	if (action == SIG_IGN) {
3430 		sigset_t mask;
3431 
3432 		sigemptyset(&mask);
3433 		sigaddset(&mask, sig);
3434 
3435 		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
3436 		flush_sigqueue_mask(&mask, &current->pending);
3437 		recalc_sigpending();
3438 	}
3439 	spin_unlock_irq(&current->sighand->siglock);
3440 }
3441 EXPORT_SYMBOL(kernel_sigaction);
3442 
3443 void __weak sigaction_compat_abi(struct k_sigaction *act,
3444 		struct k_sigaction *oact)
3445 {
3446 }
3447 
3448 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3449 {
3450 	struct task_struct *p = current, *t;
3451 	struct k_sigaction *k;
3452 	sigset_t mask;
3453 
3454 	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3455 		return -EINVAL;
3456 
3457 	k = &p->sighand->action[sig-1];
3458 
3459 	spin_lock_irq(&p->sighand->siglock);
3460 	if (oact)
3461 		*oact = *k;
3462 
3463 	sigaction_compat_abi(act, oact);
3464 
3465 	if (act) {
3466 		sigdelsetmask(&act->sa.sa_mask,
3467 			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3468 		*k = *act;
3469 		/*
3470 		 * POSIX 3.3.1.3:
3471 		 *  "Setting a signal action to SIG_IGN for a signal that is
3472 		 *   pending shall cause the pending signal to be discarded,
3473 		 *   whether or not it is blocked."
3474 		 *
3475 		 *  "Setting a signal action to SIG_DFL for a signal that is
3476 		 *   pending and whose default action is to ignore the signal
3477 		 *   (for example, SIGCHLD), shall cause the pending signal to
3478 		 *   be discarded, whether or not it is blocked"
3479 		 */
3480 		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3481 			sigemptyset(&mask);
3482 			sigaddset(&mask, sig);
3483 			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3484 			for_each_thread(p, t)
3485 				flush_sigqueue_mask(&mask, &t->pending);
3486 		}
3487 	}
3488 
3489 	spin_unlock_irq(&p->sighand->siglock);
3490 	return 0;
3491 }
3492 
3493 static int
3494 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
3495 {
3496 	struct task_struct *t = current;
3497 
3498 	if (oss) {
3499 		memset(oss, 0, sizeof(stack_t));
3500 		oss->ss_sp = (void __user *) t->sas_ss_sp;
3501 		oss->ss_size = t->sas_ss_size;
3502 		oss->ss_flags = sas_ss_flags(sp) |
3503 			(current->sas_ss_flags & SS_FLAG_BITS);
3504 	}
3505 
3506 	if (ss) {
3507 		void __user *ss_sp = ss->ss_sp;
3508 		size_t ss_size = ss->ss_size;
3509 		unsigned ss_flags = ss->ss_flags;
3510 		int ss_mode;
3511 
3512 		if (unlikely(on_sig_stack(sp)))
3513 			return -EPERM;
3514 
3515 		ss_mode = ss_flags & ~SS_FLAG_BITS;
3516 		if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3517 				ss_mode != 0))
3518 			return -EINVAL;
3519 
3520 		if (ss_mode == SS_DISABLE) {
3521 			ss_size = 0;
3522 			ss_sp = NULL;
3523 		} else {
3524 			if (unlikely(ss_size < MINSIGSTKSZ))
3525 				return -ENOMEM;
3526 		}
3527 
3528 		t->sas_ss_sp = (unsigned long) ss_sp;
3529 		t->sas_ss_size = ss_size;
3530 		t->sas_ss_flags = ss_flags;
3531 	}
3532 	return 0;
3533 }
3534 
3535 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3536 {
3537 	stack_t new, old;
3538 	int err;
3539 	if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
3540 		return -EFAULT;
3541 	err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
3542 			      current_user_stack_pointer());
3543 	if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
3544 		err = -EFAULT;
3545 	return err;
3546 }
3547 
3548 int restore_altstack(const stack_t __user *uss)
3549 {
3550 	stack_t new;
3551 	if (copy_from_user(&new, uss, sizeof(stack_t)))
3552 		return -EFAULT;
3553 	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
3554 	/* squash all but EFAULT for now */
3555 	return 0;
3556 }
3557 
3558 int __save_altstack(stack_t __user *uss, unsigned long sp)
3559 {
3560 	struct task_struct *t = current;
3561 	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3562 		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3563 		__put_user(t->sas_ss_size, &uss->ss_size);
3564 	if (err)
3565 		return err;
3566 	if (t->sas_ss_flags & SS_AUTODISARM)
3567 		sas_ss_reset(t);
3568 	return 0;
3569 }
3570 
3571 #ifdef CONFIG_COMPAT
3572 static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
3573 				 compat_stack_t __user *uoss_ptr)
3574 {
3575 	stack_t uss, uoss;
3576 	int ret;
3577 
3578 	if (uss_ptr) {
3579 		compat_stack_t uss32;
3580 		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3581 			return -EFAULT;
3582 		uss.ss_sp = compat_ptr(uss32.ss_sp);
3583 		uss.ss_flags = uss32.ss_flags;
3584 		uss.ss_size = uss32.ss_size;
3585 	}
3586 	ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
3587 			     compat_user_stack_pointer());
3588 	if (ret >= 0 && uoss_ptr)  {
3589 		compat_stack_t old;
3590 		memset(&old, 0, sizeof(old));
3591 		old.ss_sp = ptr_to_compat(uoss.ss_sp);
3592 		old.ss_flags = uoss.ss_flags;
3593 		old.ss_size = uoss.ss_size;
3594 		if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
3595 			ret = -EFAULT;
3596 	}
3597 	return ret;
3598 }
3599 
3600 COMPAT_SYSCALL_DEFINE2(sigaltstack,
3601 			const compat_stack_t __user *, uss_ptr,
3602 			compat_stack_t __user *, uoss_ptr)
3603 {
3604 	return do_compat_sigaltstack(uss_ptr, uoss_ptr);
3605 }
3606 
3607 int compat_restore_altstack(const compat_stack_t __user *uss)
3608 {
3609 	int err = do_compat_sigaltstack(uss, NULL);
3610 	/* squash all but -EFAULT for now */
3611 	return err == -EFAULT ? err : 0;
3612 }
3613 
3614 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3615 {
3616 	int err;
3617 	struct task_struct *t = current;
3618 	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3619 			 &uss->ss_sp) |
3620 		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3621 		__put_user(t->sas_ss_size, &uss->ss_size);
3622 	if (err)
3623 		return err;
3624 	if (t->sas_ss_flags & SS_AUTODISARM)
3625 		sas_ss_reset(t);
3626 	return 0;
3627 }
3628 #endif
3629 
3630 #ifdef __ARCH_WANT_SYS_SIGPENDING
3631 
3632 /**
3633  *  sys_sigpending - examine pending signals
3634  *  @uset: where mask of pending signal is returned
3635  */
3636 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
3637 {
3638 	sigset_t set;
3639 	int err;
3640 
3641 	if (sizeof(old_sigset_t) > sizeof(*uset))
3642 		return -EINVAL;
3643 
3644 	err = do_sigpending(&set);
3645 	if (!err && copy_to_user(uset, &set, sizeof(old_sigset_t)))
3646 		err = -EFAULT;
3647 	return err;
3648 }
3649 
3650 #ifdef CONFIG_COMPAT
3651 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
3652 {
3653 	sigset_t set;
3654 	int err = do_sigpending(&set);
3655 	if (!err)
3656 		err = put_user(set.sig[0], set32);
3657 	return err;
3658 }
3659 #endif
3660 
3661 #endif
3662 
3663 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3664 /**
3665  *  sys_sigprocmask - examine and change blocked signals
3666  *  @how: whether to add, remove, or set signals
3667  *  @nset: signals to add or remove (if non-null)
3668  *  @oset: previous value of signal mask if non-null
3669  *
3670  * Some platforms have their own version with special arguments;
3671  * others support only sys_rt_sigprocmask.
3672  */
3673 
3674 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3675 		old_sigset_t __user *, oset)
3676 {
3677 	old_sigset_t old_set, new_set;
3678 	sigset_t new_blocked;
3679 
3680 	old_set = current->blocked.sig[0];
3681 
3682 	if (nset) {
3683 		if (copy_from_user(&new_set, nset, sizeof(*nset)))
3684 			return -EFAULT;
3685 
3686 		new_blocked = current->blocked;
3687 
3688 		switch (how) {
3689 		case SIG_BLOCK:
3690 			sigaddsetmask(&new_blocked, new_set);
3691 			break;
3692 		case SIG_UNBLOCK:
3693 			sigdelsetmask(&new_blocked, new_set);
3694 			break;
3695 		case SIG_SETMASK:
3696 			new_blocked.sig[0] = new_set;
3697 			break;
3698 		default:
3699 			return -EINVAL;
3700 		}
3701 
3702 		set_current_blocked(&new_blocked);
3703 	}
3704 
3705 	if (oset) {
3706 		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3707 			return -EFAULT;
3708 	}
3709 
3710 	return 0;
3711 }
3712 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3713 
3714 #ifndef CONFIG_ODD_RT_SIGACTION
3715 /**
3716  *  sys_rt_sigaction - alter an action taken by a process
3717  *  @sig: signal to be sent
3718  *  @act: new sigaction
3719  *  @oact: used to save the previous sigaction
3720  *  @sigsetsize: size of sigset_t type
3721  */
3722 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3723 		const struct sigaction __user *, act,
3724 		struct sigaction __user *, oact,
3725 		size_t, sigsetsize)
3726 {
3727 	struct k_sigaction new_sa, old_sa;
3728 	int ret = -EINVAL;
3729 
3730 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3731 	if (sigsetsize != sizeof(sigset_t))
3732 		goto out;
3733 
3734 	if (act) {
3735 		if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3736 			return -EFAULT;
3737 	}
3738 
3739 	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3740 
3741 	if (!ret && oact) {
3742 		if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3743 			return -EFAULT;
3744 	}
3745 out:
3746 	return ret;
3747 }
3748 #ifdef CONFIG_COMPAT
3749 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3750 		const struct compat_sigaction __user *, act,
3751 		struct compat_sigaction __user *, oact,
3752 		compat_size_t, sigsetsize)
3753 {
3754 	struct k_sigaction new_ka, old_ka;
3755 #ifdef __ARCH_HAS_SA_RESTORER
3756 	compat_uptr_t restorer;
3757 #endif
3758 	int ret;
3759 
3760 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3761 	if (sigsetsize != sizeof(compat_sigset_t))
3762 		return -EINVAL;
3763 
3764 	if (act) {
3765 		compat_uptr_t handler;
3766 		ret = get_user(handler, &act->sa_handler);
3767 		new_ka.sa.sa_handler = compat_ptr(handler);
3768 #ifdef __ARCH_HAS_SA_RESTORER
3769 		ret |= get_user(restorer, &act->sa_restorer);
3770 		new_ka.sa.sa_restorer = compat_ptr(restorer);
3771 #endif
3772 		ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
3773 		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3774 		if (ret)
3775 			return -EFAULT;
3776 	}
3777 
3778 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3779 	if (!ret && oact) {
3780 		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3781 			       &oact->sa_handler);
3782 		ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
3783 					 sizeof(oact->sa_mask));
3784 		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3785 #ifdef __ARCH_HAS_SA_RESTORER
3786 		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3787 				&oact->sa_restorer);
3788 #endif
3789 	}
3790 	return ret;
3791 }
3792 #endif
3793 #endif /* !CONFIG_ODD_RT_SIGACTION */
3794 
3795 #ifdef CONFIG_OLD_SIGACTION
3796 SYSCALL_DEFINE3(sigaction, int, sig,
3797 		const struct old_sigaction __user *, act,
3798 	        struct old_sigaction __user *, oact)
3799 {
3800 	struct k_sigaction new_ka, old_ka;
3801 	int ret;
3802 
3803 	if (act) {
3804 		old_sigset_t mask;
3805 		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3806 		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3807 		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3808 		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3809 		    __get_user(mask, &act->sa_mask))
3810 			return -EFAULT;
3811 #ifdef __ARCH_HAS_KA_RESTORER
3812 		new_ka.ka_restorer = NULL;
3813 #endif
3814 		siginitset(&new_ka.sa.sa_mask, mask);
3815 	}
3816 
3817 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3818 
3819 	if (!ret && oact) {
3820 		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3821 		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3822 		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3823 		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3824 		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3825 			return -EFAULT;
3826 	}
3827 
3828 	return ret;
3829 }
3830 #endif
3831 #ifdef CONFIG_COMPAT_OLD_SIGACTION
3832 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3833 		const struct compat_old_sigaction __user *, act,
3834 	        struct compat_old_sigaction __user *, oact)
3835 {
3836 	struct k_sigaction new_ka, old_ka;
3837 	int ret;
3838 	compat_old_sigset_t mask;
3839 	compat_uptr_t handler, restorer;
3840 
3841 	if (act) {
3842 		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3843 		    __get_user(handler, &act->sa_handler) ||
3844 		    __get_user(restorer, &act->sa_restorer) ||
3845 		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3846 		    __get_user(mask, &act->sa_mask))
3847 			return -EFAULT;
3848 
3849 #ifdef __ARCH_HAS_KA_RESTORER
3850 		new_ka.ka_restorer = NULL;
3851 #endif
3852 		new_ka.sa.sa_handler = compat_ptr(handler);
3853 		new_ka.sa.sa_restorer = compat_ptr(restorer);
3854 		siginitset(&new_ka.sa.sa_mask, mask);
3855 	}
3856 
3857 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3858 
3859 	if (!ret && oact) {
3860 		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3861 		    __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3862 			       &oact->sa_handler) ||
3863 		    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3864 			       &oact->sa_restorer) ||
3865 		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3866 		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3867 			return -EFAULT;
3868 	}
3869 	return ret;
3870 }
3871 #endif
3872 
3873 #ifdef CONFIG_SGETMASK_SYSCALL
3874 
3875 /*
3876  * For backwards compatibility.  Functionality superseded by sigprocmask.
3877  */
3878 SYSCALL_DEFINE0(sgetmask)
3879 {
3880 	/* SMP safe */
3881 	return current->blocked.sig[0];
3882 }
3883 
3884 SYSCALL_DEFINE1(ssetmask, int, newmask)
3885 {
3886 	int old = current->blocked.sig[0];
3887 	sigset_t newset;
3888 
3889 	siginitset(&newset, newmask);
3890 	set_current_blocked(&newset);
3891 
3892 	return old;
3893 }
3894 #endif /* CONFIG_SGETMASK_SYSCALL */
3895 
3896 #ifdef __ARCH_WANT_SYS_SIGNAL
3897 /*
3898  * For backwards compatibility.  Functionality superseded by sigaction.
3899  */
3900 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3901 {
3902 	struct k_sigaction new_sa, old_sa;
3903 	int ret;
3904 
3905 	new_sa.sa.sa_handler = handler;
3906 	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3907 	sigemptyset(&new_sa.sa.sa_mask);
3908 
3909 	ret = do_sigaction(sig, &new_sa, &old_sa);
3910 
3911 	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3912 }
3913 #endif /* __ARCH_WANT_SYS_SIGNAL */
3914 
3915 #ifdef __ARCH_WANT_SYS_PAUSE
3916 
3917 SYSCALL_DEFINE0(pause)
3918 {
3919 	while (!signal_pending(current)) {
3920 		__set_current_state(TASK_INTERRUPTIBLE);
3921 		schedule();
3922 	}
3923 	return -ERESTARTNOHAND;
3924 }
3925 
3926 #endif
3927 
3928 static int sigsuspend(sigset_t *set)
3929 {
3930 	current->saved_sigmask = current->blocked;
3931 	set_current_blocked(set);
3932 
3933 	while (!signal_pending(current)) {
3934 		__set_current_state(TASK_INTERRUPTIBLE);
3935 		schedule();
3936 	}
3937 	set_restore_sigmask();
3938 	return -ERESTARTNOHAND;
3939 }
3940 
3941 /**
3942  *  sys_rt_sigsuspend - replace the signal mask for a value with the
3943  *	@unewset value until a signal is received
3944  *  @unewset: new signal mask value
3945  *  @sigsetsize: size of sigset_t type
3946  */
3947 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3948 {
3949 	sigset_t newset;
3950 
3951 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3952 	if (sigsetsize != sizeof(sigset_t))
3953 		return -EINVAL;
3954 
3955 	if (copy_from_user(&newset, unewset, sizeof(newset)))
3956 		return -EFAULT;
3957 	return sigsuspend(&newset);
3958 }
3959 
3960 #ifdef CONFIG_COMPAT
3961 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3962 {
3963 	sigset_t newset;
3964 
3965 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3966 	if (sigsetsize != sizeof(sigset_t))
3967 		return -EINVAL;
3968 
3969 	if (get_compat_sigset(&newset, unewset))
3970 		return -EFAULT;
3971 	return sigsuspend(&newset);
3972 }
3973 #endif
3974 
3975 #ifdef CONFIG_OLD_SIGSUSPEND
3976 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3977 {
3978 	sigset_t blocked;
3979 	siginitset(&blocked, mask);
3980 	return sigsuspend(&blocked);
3981 }
3982 #endif
3983 #ifdef CONFIG_OLD_SIGSUSPEND3
3984 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3985 {
3986 	sigset_t blocked;
3987 	siginitset(&blocked, mask);
3988 	return sigsuspend(&blocked);
3989 }
3990 #endif
3991 
3992 __weak const char *arch_vma_name(struct vm_area_struct *vma)
3993 {
3994 	return NULL;
3995 }
3996 
3997 void __init signals_init(void)
3998 {
3999 	/* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
4000 	BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
4001 		!= offsetof(struct siginfo, _sifields._pad));
4002 	BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4003 
4004 	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
4005 }
4006 
4007 #ifdef CONFIG_KGDB_KDB
4008 #include <linux/kdb.h>
4009 /*
4010  * kdb_send_sig - Allows kdb to send signals without exposing
4011  * signal internals.  This function checks if the required locks are
4012  * available before calling the main signal code, to avoid kdb
4013  * deadlocks.
4014  */
4015 void kdb_send_sig(struct task_struct *t, int sig)
4016 {
4017 	static struct task_struct *kdb_prev_t;
4018 	int new_t, ret;
4019 	if (!spin_trylock(&t->sighand->siglock)) {
4020 		kdb_printf("Can't do kill command now.\n"
4021 			   "The sigmask lock is held somewhere else in "
4022 			   "kernel, try again later\n");
4023 		return;
4024 	}
4025 	new_t = kdb_prev_t != t;
4026 	kdb_prev_t = t;
4027 	if (t->state != TASK_RUNNING && new_t) {
4028 		spin_unlock(&t->sighand->siglock);
4029 		kdb_printf("Process is not RUNNING, sending a signal from "
4030 			   "kdb risks deadlock\n"
4031 			   "on the run queue locks. "
4032 			   "The signal has _not_ been sent.\n"
4033 			   "Reissue the kill command if you want to risk "
4034 			   "the deadlock.\n");
4035 		return;
4036 	}
4037 	ret = send_signal(sig, SEND_SIG_PRIV, t, false);
4038 	spin_unlock(&t->sighand->siglock);
4039 	if (ret)
4040 		kdb_printf("Fail to deliver Signal %d to process %d.\n",
4041 			   sig, t->pid);
4042 	else
4043 		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4044 }
4045 #endif	/* CONFIG_KGDB_KDB */
4046