xref: /openbmc/linux/kernel/signal.c (revision afb46f79)
1 /*
2  *  linux/kernel/signal.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  *
6  *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
7  *
8  *  2003-06-02  Jim Houston - Concurrent Computer Corp.
9  *		Changes to use preallocated sigqueue structures
10  *		to allow signals to be sent reliably.
11  */
12 
13 #include <linux/slab.h>
14 #include <linux/export.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
17 #include <linux/fs.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/coredump.h>
21 #include <linux/security.h>
22 #include <linux/syscalls.h>
23 #include <linux/ptrace.h>
24 #include <linux/signal.h>
25 #include <linux/signalfd.h>
26 #include <linux/ratelimit.h>
27 #include <linux/tracehook.h>
28 #include <linux/capability.h>
29 #include <linux/freezer.h>
30 #include <linux/pid_namespace.h>
31 #include <linux/nsproxy.h>
32 #include <linux/user_namespace.h>
33 #include <linux/uprobes.h>
34 #include <linux/compat.h>
35 #include <linux/cn_proc.h>
36 #include <linux/compiler.h>
37 
38 #define CREATE_TRACE_POINTS
39 #include <trace/events/signal.h>
40 
41 #include <asm/param.h>
42 #include <asm/uaccess.h>
43 #include <asm/unistd.h>
44 #include <asm/siginfo.h>
45 #include <asm/cacheflush.h>
46 #include "audit.h"	/* audit_signal_info() */
47 
48 /*
49  * SLAB caches for signal bits.
50  */
51 
52 static struct kmem_cache *sigqueue_cachep;
53 
54 int print_fatal_signals __read_mostly;
55 
56 static void __user *sig_handler(struct task_struct *t, int sig)
57 {
58 	return t->sighand->action[sig - 1].sa.sa_handler;
59 }
60 
61 static int sig_handler_ignored(void __user *handler, int sig)
62 {
63 	/* Is it explicitly or implicitly ignored? */
64 	return handler == SIG_IGN ||
65 		(handler == SIG_DFL && sig_kernel_ignore(sig));
66 }
67 
68 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
69 {
70 	void __user *handler;
71 
72 	handler = sig_handler(t, sig);
73 
74 	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
75 			handler == SIG_DFL && !force)
76 		return 1;
77 
78 	return sig_handler_ignored(handler, sig);
79 }
80 
81 static int sig_ignored(struct task_struct *t, int sig, bool force)
82 {
83 	/*
84 	 * Blocked signals are never ignored, since the
85 	 * signal handler may change by the time it is
86 	 * unblocked.
87 	 */
88 	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
89 		return 0;
90 
91 	if (!sig_task_ignored(t, sig, force))
92 		return 0;
93 
94 	/*
95 	 * Tracers may want to know about even ignored signals.
96 	 */
97 	return !t->ptrace;
98 }
99 
100 /*
101  * Re-calculate pending state from the set of locally pending
102  * signals, globally pending signals, and blocked signals.
103  */
104 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105 {
106 	unsigned long ready;
107 	long i;
108 
109 	switch (_NSIG_WORDS) {
110 	default:
111 		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112 			ready |= signal->sig[i] &~ blocked->sig[i];
113 		break;
114 
115 	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
116 		ready |= signal->sig[2] &~ blocked->sig[2];
117 		ready |= signal->sig[1] &~ blocked->sig[1];
118 		ready |= signal->sig[0] &~ blocked->sig[0];
119 		break;
120 
121 	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
122 		ready |= signal->sig[0] &~ blocked->sig[0];
123 		break;
124 
125 	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
126 	}
127 	return ready !=	0;
128 }
129 
130 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131 
132 static int recalc_sigpending_tsk(struct task_struct *t)
133 {
134 	if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135 	    PENDING(&t->pending, &t->blocked) ||
136 	    PENDING(&t->signal->shared_pending, &t->blocked)) {
137 		set_tsk_thread_flag(t, TIF_SIGPENDING);
138 		return 1;
139 	}
140 	/*
141 	 * We must never clear the flag in another thread, or in current
142 	 * when it's possible the current syscall is returning -ERESTART*.
143 	 * So we don't clear it here, and only callers who know they should do.
144 	 */
145 	return 0;
146 }
147 
148 /*
149  * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150  * This is superfluous when called on current, the wakeup is a harmless no-op.
151  */
152 void recalc_sigpending_and_wake(struct task_struct *t)
153 {
154 	if (recalc_sigpending_tsk(t))
155 		signal_wake_up(t, 0);
156 }
157 
158 void recalc_sigpending(void)
159 {
160 	if (!recalc_sigpending_tsk(current) && !freezing(current))
161 		clear_thread_flag(TIF_SIGPENDING);
162 
163 }
164 
165 /* Given the mask, find the first available signal that should be serviced. */
166 
167 #define SYNCHRONOUS_MASK \
168 	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169 	 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170 
171 int next_signal(struct sigpending *pending, sigset_t *mask)
172 {
173 	unsigned long i, *s, *m, x;
174 	int sig = 0;
175 
176 	s = pending->signal.sig;
177 	m = mask->sig;
178 
179 	/*
180 	 * Handle the first word specially: it contains the
181 	 * synchronous signals that need to be dequeued first.
182 	 */
183 	x = *s &~ *m;
184 	if (x) {
185 		if (x & SYNCHRONOUS_MASK)
186 			x &= SYNCHRONOUS_MASK;
187 		sig = ffz(~x) + 1;
188 		return sig;
189 	}
190 
191 	switch (_NSIG_WORDS) {
192 	default:
193 		for (i = 1; i < _NSIG_WORDS; ++i) {
194 			x = *++s &~ *++m;
195 			if (!x)
196 				continue;
197 			sig = ffz(~x) + i*_NSIG_BPW + 1;
198 			break;
199 		}
200 		break;
201 
202 	case 2:
203 		x = s[1] &~ m[1];
204 		if (!x)
205 			break;
206 		sig = ffz(~x) + _NSIG_BPW + 1;
207 		break;
208 
209 	case 1:
210 		/* Nothing to do */
211 		break;
212 	}
213 
214 	return sig;
215 }
216 
217 static inline void print_dropped_signal(int sig)
218 {
219 	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220 
221 	if (!print_fatal_signals)
222 		return;
223 
224 	if (!__ratelimit(&ratelimit_state))
225 		return;
226 
227 	printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228 				current->comm, current->pid, sig);
229 }
230 
231 /**
232  * task_set_jobctl_pending - set jobctl pending bits
233  * @task: target task
234  * @mask: pending bits to set
235  *
236  * Clear @mask from @task->jobctl.  @mask must be subset of
237  * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238  * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
239  * cleared.  If @task is already being killed or exiting, this function
240  * becomes noop.
241  *
242  * CONTEXT:
243  * Must be called with @task->sighand->siglock held.
244  *
245  * RETURNS:
246  * %true if @mask is set, %false if made noop because @task was dying.
247  */
248 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
249 {
250 	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251 			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252 	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253 
254 	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255 		return false;
256 
257 	if (mask & JOBCTL_STOP_SIGMASK)
258 		task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259 
260 	task->jobctl |= mask;
261 	return true;
262 }
263 
264 /**
265  * task_clear_jobctl_trapping - clear jobctl trapping bit
266  * @task: target task
267  *
268  * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269  * Clear it and wake up the ptracer.  Note that we don't need any further
270  * locking.  @task->siglock guarantees that @task->parent points to the
271  * ptracer.
272  *
273  * CONTEXT:
274  * Must be called with @task->sighand->siglock held.
275  */
276 void task_clear_jobctl_trapping(struct task_struct *task)
277 {
278 	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279 		task->jobctl &= ~JOBCTL_TRAPPING;
280 		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
281 	}
282 }
283 
284 /**
285  * task_clear_jobctl_pending - clear jobctl pending bits
286  * @task: target task
287  * @mask: pending bits to clear
288  *
289  * Clear @mask from @task->jobctl.  @mask must be subset of
290  * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
291  * STOP bits are cleared together.
292  *
293  * If clearing of @mask leaves no stop or trap pending, this function calls
294  * task_clear_jobctl_trapping().
295  *
296  * CONTEXT:
297  * Must be called with @task->sighand->siglock held.
298  */
299 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
300 {
301 	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
302 
303 	if (mask & JOBCTL_STOP_PENDING)
304 		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
305 
306 	task->jobctl &= ~mask;
307 
308 	if (!(task->jobctl & JOBCTL_PENDING_MASK))
309 		task_clear_jobctl_trapping(task);
310 }
311 
312 /**
313  * task_participate_group_stop - participate in a group stop
314  * @task: task participating in a group stop
315  *
316  * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
317  * Group stop states are cleared and the group stop count is consumed if
318  * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
319  * stop, the appropriate %SIGNAL_* flags are set.
320  *
321  * CONTEXT:
322  * Must be called with @task->sighand->siglock held.
323  *
324  * RETURNS:
325  * %true if group stop completion should be notified to the parent, %false
326  * otherwise.
327  */
328 static bool task_participate_group_stop(struct task_struct *task)
329 {
330 	struct signal_struct *sig = task->signal;
331 	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
332 
333 	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
334 
335 	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
336 
337 	if (!consume)
338 		return false;
339 
340 	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
341 		sig->group_stop_count--;
342 
343 	/*
344 	 * Tell the caller to notify completion iff we are entering into a
345 	 * fresh group stop.  Read comment in do_signal_stop() for details.
346 	 */
347 	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
348 		sig->flags = SIGNAL_STOP_STOPPED;
349 		return true;
350 	}
351 	return false;
352 }
353 
354 /*
355  * allocate a new signal queue record
356  * - this may be called without locks if and only if t == current, otherwise an
357  *   appropriate lock must be held to stop the target task from exiting
358  */
359 static struct sigqueue *
360 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
361 {
362 	struct sigqueue *q = NULL;
363 	struct user_struct *user;
364 
365 	/*
366 	 * Protect access to @t credentials. This can go away when all
367 	 * callers hold rcu read lock.
368 	 */
369 	rcu_read_lock();
370 	user = get_uid(__task_cred(t)->user);
371 	atomic_inc(&user->sigpending);
372 	rcu_read_unlock();
373 
374 	if (override_rlimit ||
375 	    atomic_read(&user->sigpending) <=
376 			task_rlimit(t, RLIMIT_SIGPENDING)) {
377 		q = kmem_cache_alloc(sigqueue_cachep, flags);
378 	} else {
379 		print_dropped_signal(sig);
380 	}
381 
382 	if (unlikely(q == NULL)) {
383 		atomic_dec(&user->sigpending);
384 		free_uid(user);
385 	} else {
386 		INIT_LIST_HEAD(&q->list);
387 		q->flags = 0;
388 		q->user = user;
389 	}
390 
391 	return q;
392 }
393 
394 static void __sigqueue_free(struct sigqueue *q)
395 {
396 	if (q->flags & SIGQUEUE_PREALLOC)
397 		return;
398 	atomic_dec(&q->user->sigpending);
399 	free_uid(q->user);
400 	kmem_cache_free(sigqueue_cachep, q);
401 }
402 
403 void flush_sigqueue(struct sigpending *queue)
404 {
405 	struct sigqueue *q;
406 
407 	sigemptyset(&queue->signal);
408 	while (!list_empty(&queue->list)) {
409 		q = list_entry(queue->list.next, struct sigqueue , list);
410 		list_del_init(&q->list);
411 		__sigqueue_free(q);
412 	}
413 }
414 
415 /*
416  * Flush all pending signals for a task.
417  */
418 void __flush_signals(struct task_struct *t)
419 {
420 	clear_tsk_thread_flag(t, TIF_SIGPENDING);
421 	flush_sigqueue(&t->pending);
422 	flush_sigqueue(&t->signal->shared_pending);
423 }
424 
425 void flush_signals(struct task_struct *t)
426 {
427 	unsigned long flags;
428 
429 	spin_lock_irqsave(&t->sighand->siglock, flags);
430 	__flush_signals(t);
431 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
432 }
433 
434 static void __flush_itimer_signals(struct sigpending *pending)
435 {
436 	sigset_t signal, retain;
437 	struct sigqueue *q, *n;
438 
439 	signal = pending->signal;
440 	sigemptyset(&retain);
441 
442 	list_for_each_entry_safe(q, n, &pending->list, list) {
443 		int sig = q->info.si_signo;
444 
445 		if (likely(q->info.si_code != SI_TIMER)) {
446 			sigaddset(&retain, sig);
447 		} else {
448 			sigdelset(&signal, sig);
449 			list_del_init(&q->list);
450 			__sigqueue_free(q);
451 		}
452 	}
453 
454 	sigorsets(&pending->signal, &signal, &retain);
455 }
456 
457 void flush_itimer_signals(void)
458 {
459 	struct task_struct *tsk = current;
460 	unsigned long flags;
461 
462 	spin_lock_irqsave(&tsk->sighand->siglock, flags);
463 	__flush_itimer_signals(&tsk->pending);
464 	__flush_itimer_signals(&tsk->signal->shared_pending);
465 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
466 }
467 
468 void ignore_signals(struct task_struct *t)
469 {
470 	int i;
471 
472 	for (i = 0; i < _NSIG; ++i)
473 		t->sighand->action[i].sa.sa_handler = SIG_IGN;
474 
475 	flush_signals(t);
476 }
477 
478 /*
479  * Flush all handlers for a task.
480  */
481 
482 void
483 flush_signal_handlers(struct task_struct *t, int force_default)
484 {
485 	int i;
486 	struct k_sigaction *ka = &t->sighand->action[0];
487 	for (i = _NSIG ; i != 0 ; i--) {
488 		if (force_default || ka->sa.sa_handler != SIG_IGN)
489 			ka->sa.sa_handler = SIG_DFL;
490 		ka->sa.sa_flags = 0;
491 #ifdef __ARCH_HAS_SA_RESTORER
492 		ka->sa.sa_restorer = NULL;
493 #endif
494 		sigemptyset(&ka->sa.sa_mask);
495 		ka++;
496 	}
497 }
498 
499 int unhandled_signal(struct task_struct *tsk, int sig)
500 {
501 	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
502 	if (is_global_init(tsk))
503 		return 1;
504 	if (handler != SIG_IGN && handler != SIG_DFL)
505 		return 0;
506 	/* if ptraced, let the tracer determine */
507 	return !tsk->ptrace;
508 }
509 
510 /*
511  * Notify the system that a driver wants to block all signals for this
512  * process, and wants to be notified if any signals at all were to be
513  * sent/acted upon.  If the notifier routine returns non-zero, then the
514  * signal will be acted upon after all.  If the notifier routine returns 0,
515  * then then signal will be blocked.  Only one block per process is
516  * allowed.  priv is a pointer to private data that the notifier routine
517  * can use to determine if the signal should be blocked or not.
518  */
519 void
520 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
521 {
522 	unsigned long flags;
523 
524 	spin_lock_irqsave(&current->sighand->siglock, flags);
525 	current->notifier_mask = mask;
526 	current->notifier_data = priv;
527 	current->notifier = notifier;
528 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
529 }
530 
531 /* Notify the system that blocking has ended. */
532 
533 void
534 unblock_all_signals(void)
535 {
536 	unsigned long flags;
537 
538 	spin_lock_irqsave(&current->sighand->siglock, flags);
539 	current->notifier = NULL;
540 	current->notifier_data = NULL;
541 	recalc_sigpending();
542 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
543 }
544 
545 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
546 {
547 	struct sigqueue *q, *first = NULL;
548 
549 	/*
550 	 * Collect the siginfo appropriate to this signal.  Check if
551 	 * there is another siginfo for the same signal.
552 	*/
553 	list_for_each_entry(q, &list->list, list) {
554 		if (q->info.si_signo == sig) {
555 			if (first)
556 				goto still_pending;
557 			first = q;
558 		}
559 	}
560 
561 	sigdelset(&list->signal, sig);
562 
563 	if (first) {
564 still_pending:
565 		list_del_init(&first->list);
566 		copy_siginfo(info, &first->info);
567 		__sigqueue_free(first);
568 	} else {
569 		/*
570 		 * Ok, it wasn't in the queue.  This must be
571 		 * a fast-pathed signal or we must have been
572 		 * out of queue space.  So zero out the info.
573 		 */
574 		info->si_signo = sig;
575 		info->si_errno = 0;
576 		info->si_code = SI_USER;
577 		info->si_pid = 0;
578 		info->si_uid = 0;
579 	}
580 }
581 
582 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
583 			siginfo_t *info)
584 {
585 	int sig = next_signal(pending, mask);
586 
587 	if (sig) {
588 		if (current->notifier) {
589 			if (sigismember(current->notifier_mask, sig)) {
590 				if (!(current->notifier)(current->notifier_data)) {
591 					clear_thread_flag(TIF_SIGPENDING);
592 					return 0;
593 				}
594 			}
595 		}
596 
597 		collect_signal(sig, pending, info);
598 	}
599 
600 	return sig;
601 }
602 
603 /*
604  * Dequeue a signal and return the element to the caller, which is
605  * expected to free it.
606  *
607  * All callers have to hold the siglock.
608  */
609 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
610 {
611 	int signr;
612 
613 	/* We only dequeue private signals from ourselves, we don't let
614 	 * signalfd steal them
615 	 */
616 	signr = __dequeue_signal(&tsk->pending, mask, info);
617 	if (!signr) {
618 		signr = __dequeue_signal(&tsk->signal->shared_pending,
619 					 mask, info);
620 		/*
621 		 * itimer signal ?
622 		 *
623 		 * itimers are process shared and we restart periodic
624 		 * itimers in the signal delivery path to prevent DoS
625 		 * attacks in the high resolution timer case. This is
626 		 * compliant with the old way of self-restarting
627 		 * itimers, as the SIGALRM is a legacy signal and only
628 		 * queued once. Changing the restart behaviour to
629 		 * restart the timer in the signal dequeue path is
630 		 * reducing the timer noise on heavy loaded !highres
631 		 * systems too.
632 		 */
633 		if (unlikely(signr == SIGALRM)) {
634 			struct hrtimer *tmr = &tsk->signal->real_timer;
635 
636 			if (!hrtimer_is_queued(tmr) &&
637 			    tsk->signal->it_real_incr.tv64 != 0) {
638 				hrtimer_forward(tmr, tmr->base->get_time(),
639 						tsk->signal->it_real_incr);
640 				hrtimer_restart(tmr);
641 			}
642 		}
643 	}
644 
645 	recalc_sigpending();
646 	if (!signr)
647 		return 0;
648 
649 	if (unlikely(sig_kernel_stop(signr))) {
650 		/*
651 		 * Set a marker that we have dequeued a stop signal.  Our
652 		 * caller might release the siglock and then the pending
653 		 * stop signal it is about to process is no longer in the
654 		 * pending bitmasks, but must still be cleared by a SIGCONT
655 		 * (and overruled by a SIGKILL).  So those cases clear this
656 		 * shared flag after we've set it.  Note that this flag may
657 		 * remain set after the signal we return is ignored or
658 		 * handled.  That doesn't matter because its only purpose
659 		 * is to alert stop-signal processing code when another
660 		 * processor has come along and cleared the flag.
661 		 */
662 		current->jobctl |= JOBCTL_STOP_DEQUEUED;
663 	}
664 	if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
665 		/*
666 		 * Release the siglock to ensure proper locking order
667 		 * of timer locks outside of siglocks.  Note, we leave
668 		 * irqs disabled here, since the posix-timers code is
669 		 * about to disable them again anyway.
670 		 */
671 		spin_unlock(&tsk->sighand->siglock);
672 		do_schedule_next_timer(info);
673 		spin_lock(&tsk->sighand->siglock);
674 	}
675 	return signr;
676 }
677 
678 /*
679  * Tell a process that it has a new active signal..
680  *
681  * NOTE! we rely on the previous spin_lock to
682  * lock interrupts for us! We can only be called with
683  * "siglock" held, and the local interrupt must
684  * have been disabled when that got acquired!
685  *
686  * No need to set need_resched since signal event passing
687  * goes through ->blocked
688  */
689 void signal_wake_up_state(struct task_struct *t, unsigned int state)
690 {
691 	set_tsk_thread_flag(t, TIF_SIGPENDING);
692 	/*
693 	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
694 	 * case. We don't check t->state here because there is a race with it
695 	 * executing another processor and just now entering stopped state.
696 	 * By using wake_up_state, we ensure the process will wake up and
697 	 * handle its death signal.
698 	 */
699 	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
700 		kick_process(t);
701 }
702 
703 /*
704  * Remove signals in mask from the pending set and queue.
705  * Returns 1 if any signals were found.
706  *
707  * All callers must be holding the siglock.
708  *
709  * This version takes a sigset mask and looks at all signals,
710  * not just those in the first mask word.
711  */
712 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
713 {
714 	struct sigqueue *q, *n;
715 	sigset_t m;
716 
717 	sigandsets(&m, mask, &s->signal);
718 	if (sigisemptyset(&m))
719 		return 0;
720 
721 	sigandnsets(&s->signal, &s->signal, mask);
722 	list_for_each_entry_safe(q, n, &s->list, list) {
723 		if (sigismember(mask, q->info.si_signo)) {
724 			list_del_init(&q->list);
725 			__sigqueue_free(q);
726 		}
727 	}
728 	return 1;
729 }
730 /*
731  * Remove signals in mask from the pending set and queue.
732  * Returns 1 if any signals were found.
733  *
734  * All callers must be holding the siglock.
735  */
736 static int rm_from_queue(unsigned long mask, struct sigpending *s)
737 {
738 	struct sigqueue *q, *n;
739 
740 	if (!sigtestsetmask(&s->signal, mask))
741 		return 0;
742 
743 	sigdelsetmask(&s->signal, mask);
744 	list_for_each_entry_safe(q, n, &s->list, list) {
745 		if (q->info.si_signo < SIGRTMIN &&
746 		    (mask & sigmask(q->info.si_signo))) {
747 			list_del_init(&q->list);
748 			__sigqueue_free(q);
749 		}
750 	}
751 	return 1;
752 }
753 
754 static inline int is_si_special(const struct siginfo *info)
755 {
756 	return info <= SEND_SIG_FORCED;
757 }
758 
759 static inline bool si_fromuser(const struct siginfo *info)
760 {
761 	return info == SEND_SIG_NOINFO ||
762 		(!is_si_special(info) && SI_FROMUSER(info));
763 }
764 
765 /*
766  * called with RCU read lock from check_kill_permission()
767  */
768 static int kill_ok_by_cred(struct task_struct *t)
769 {
770 	const struct cred *cred = current_cred();
771 	const struct cred *tcred = __task_cred(t);
772 
773 	if (uid_eq(cred->euid, tcred->suid) ||
774 	    uid_eq(cred->euid, tcred->uid)  ||
775 	    uid_eq(cred->uid,  tcred->suid) ||
776 	    uid_eq(cred->uid,  tcred->uid))
777 		return 1;
778 
779 	if (ns_capable(tcred->user_ns, CAP_KILL))
780 		return 1;
781 
782 	return 0;
783 }
784 
785 /*
786  * Bad permissions for sending the signal
787  * - the caller must hold the RCU read lock
788  */
789 static int check_kill_permission(int sig, struct siginfo *info,
790 				 struct task_struct *t)
791 {
792 	struct pid *sid;
793 	int error;
794 
795 	if (!valid_signal(sig))
796 		return -EINVAL;
797 
798 	if (!si_fromuser(info))
799 		return 0;
800 
801 	error = audit_signal_info(sig, t); /* Let audit system see the signal */
802 	if (error)
803 		return error;
804 
805 	if (!same_thread_group(current, t) &&
806 	    !kill_ok_by_cred(t)) {
807 		switch (sig) {
808 		case SIGCONT:
809 			sid = task_session(t);
810 			/*
811 			 * We don't return the error if sid == NULL. The
812 			 * task was unhashed, the caller must notice this.
813 			 */
814 			if (!sid || sid == task_session(current))
815 				break;
816 		default:
817 			return -EPERM;
818 		}
819 	}
820 
821 	return security_task_kill(t, info, sig, 0);
822 }
823 
824 /**
825  * ptrace_trap_notify - schedule trap to notify ptracer
826  * @t: tracee wanting to notify tracer
827  *
828  * This function schedules sticky ptrace trap which is cleared on the next
829  * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
830  * ptracer.
831  *
832  * If @t is running, STOP trap will be taken.  If trapped for STOP and
833  * ptracer is listening for events, tracee is woken up so that it can
834  * re-trap for the new event.  If trapped otherwise, STOP trap will be
835  * eventually taken without returning to userland after the existing traps
836  * are finished by PTRACE_CONT.
837  *
838  * CONTEXT:
839  * Must be called with @task->sighand->siglock held.
840  */
841 static void ptrace_trap_notify(struct task_struct *t)
842 {
843 	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
844 	assert_spin_locked(&t->sighand->siglock);
845 
846 	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
847 	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
848 }
849 
850 /*
851  * Handle magic process-wide effects of stop/continue signals. Unlike
852  * the signal actions, these happen immediately at signal-generation
853  * time regardless of blocking, ignoring, or handling.  This does the
854  * actual continuing for SIGCONT, but not the actual stopping for stop
855  * signals. The process stop is done as a signal action for SIG_DFL.
856  *
857  * Returns true if the signal should be actually delivered, otherwise
858  * it should be dropped.
859  */
860 static bool prepare_signal(int sig, struct task_struct *p, bool force)
861 {
862 	struct signal_struct *signal = p->signal;
863 	struct task_struct *t;
864 
865 	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
866 		if (signal->flags & SIGNAL_GROUP_COREDUMP)
867 			return sig == SIGKILL;
868 		/*
869 		 * The process is in the middle of dying, nothing to do.
870 		 */
871 	} else if (sig_kernel_stop(sig)) {
872 		/*
873 		 * This is a stop signal.  Remove SIGCONT from all queues.
874 		 */
875 		rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
876 		t = p;
877 		do {
878 			rm_from_queue(sigmask(SIGCONT), &t->pending);
879 		} while_each_thread(p, t);
880 	} else if (sig == SIGCONT) {
881 		unsigned int why;
882 		/*
883 		 * Remove all stop signals from all queues, wake all threads.
884 		 */
885 		rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
886 		t = p;
887 		do {
888 			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
889 			rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
890 			if (likely(!(t->ptrace & PT_SEIZED)))
891 				wake_up_state(t, __TASK_STOPPED);
892 			else
893 				ptrace_trap_notify(t);
894 		} while_each_thread(p, t);
895 
896 		/*
897 		 * Notify the parent with CLD_CONTINUED if we were stopped.
898 		 *
899 		 * If we were in the middle of a group stop, we pretend it
900 		 * was already finished, and then continued. Since SIGCHLD
901 		 * doesn't queue we report only CLD_STOPPED, as if the next
902 		 * CLD_CONTINUED was dropped.
903 		 */
904 		why = 0;
905 		if (signal->flags & SIGNAL_STOP_STOPPED)
906 			why |= SIGNAL_CLD_CONTINUED;
907 		else if (signal->group_stop_count)
908 			why |= SIGNAL_CLD_STOPPED;
909 
910 		if (why) {
911 			/*
912 			 * The first thread which returns from do_signal_stop()
913 			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
914 			 * notify its parent. See get_signal_to_deliver().
915 			 */
916 			signal->flags = why | SIGNAL_STOP_CONTINUED;
917 			signal->group_stop_count = 0;
918 			signal->group_exit_code = 0;
919 		}
920 	}
921 
922 	return !sig_ignored(p, sig, force);
923 }
924 
925 /*
926  * Test if P wants to take SIG.  After we've checked all threads with this,
927  * it's equivalent to finding no threads not blocking SIG.  Any threads not
928  * blocking SIG were ruled out because they are not running and already
929  * have pending signals.  Such threads will dequeue from the shared queue
930  * as soon as they're available, so putting the signal on the shared queue
931  * will be equivalent to sending it to one such thread.
932  */
933 static inline int wants_signal(int sig, struct task_struct *p)
934 {
935 	if (sigismember(&p->blocked, sig))
936 		return 0;
937 	if (p->flags & PF_EXITING)
938 		return 0;
939 	if (sig == SIGKILL)
940 		return 1;
941 	if (task_is_stopped_or_traced(p))
942 		return 0;
943 	return task_curr(p) || !signal_pending(p);
944 }
945 
946 static void complete_signal(int sig, struct task_struct *p, int group)
947 {
948 	struct signal_struct *signal = p->signal;
949 	struct task_struct *t;
950 
951 	/*
952 	 * Now find a thread we can wake up to take the signal off the queue.
953 	 *
954 	 * If the main thread wants the signal, it gets first crack.
955 	 * Probably the least surprising to the average bear.
956 	 */
957 	if (wants_signal(sig, p))
958 		t = p;
959 	else if (!group || thread_group_empty(p))
960 		/*
961 		 * There is just one thread and it does not need to be woken.
962 		 * It will dequeue unblocked signals before it runs again.
963 		 */
964 		return;
965 	else {
966 		/*
967 		 * Otherwise try to find a suitable thread.
968 		 */
969 		t = signal->curr_target;
970 		while (!wants_signal(sig, t)) {
971 			t = next_thread(t);
972 			if (t == signal->curr_target)
973 				/*
974 				 * No thread needs to be woken.
975 				 * Any eligible threads will see
976 				 * the signal in the queue soon.
977 				 */
978 				return;
979 		}
980 		signal->curr_target = t;
981 	}
982 
983 	/*
984 	 * Found a killable thread.  If the signal will be fatal,
985 	 * then start taking the whole group down immediately.
986 	 */
987 	if (sig_fatal(p, sig) &&
988 	    !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
989 	    !sigismember(&t->real_blocked, sig) &&
990 	    (sig == SIGKILL || !t->ptrace)) {
991 		/*
992 		 * This signal will be fatal to the whole group.
993 		 */
994 		if (!sig_kernel_coredump(sig)) {
995 			/*
996 			 * Start a group exit and wake everybody up.
997 			 * This way we don't have other threads
998 			 * running and doing things after a slower
999 			 * thread has the fatal signal pending.
1000 			 */
1001 			signal->flags = SIGNAL_GROUP_EXIT;
1002 			signal->group_exit_code = sig;
1003 			signal->group_stop_count = 0;
1004 			t = p;
1005 			do {
1006 				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1007 				sigaddset(&t->pending.signal, SIGKILL);
1008 				signal_wake_up(t, 1);
1009 			} while_each_thread(p, t);
1010 			return;
1011 		}
1012 	}
1013 
1014 	/*
1015 	 * The signal is already in the shared-pending queue.
1016 	 * Tell the chosen thread to wake up and dequeue it.
1017 	 */
1018 	signal_wake_up(t, sig == SIGKILL);
1019 	return;
1020 }
1021 
1022 static inline int legacy_queue(struct sigpending *signals, int sig)
1023 {
1024 	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1025 }
1026 
1027 #ifdef CONFIG_USER_NS
1028 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1029 {
1030 	if (current_user_ns() == task_cred_xxx(t, user_ns))
1031 		return;
1032 
1033 	if (SI_FROMKERNEL(info))
1034 		return;
1035 
1036 	rcu_read_lock();
1037 	info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1038 					make_kuid(current_user_ns(), info->si_uid));
1039 	rcu_read_unlock();
1040 }
1041 #else
1042 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1043 {
1044 	return;
1045 }
1046 #endif
1047 
1048 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1049 			int group, int from_ancestor_ns)
1050 {
1051 	struct sigpending *pending;
1052 	struct sigqueue *q;
1053 	int override_rlimit;
1054 	int ret = 0, result;
1055 
1056 	assert_spin_locked(&t->sighand->siglock);
1057 
1058 	result = TRACE_SIGNAL_IGNORED;
1059 	if (!prepare_signal(sig, t,
1060 			from_ancestor_ns || (info == SEND_SIG_FORCED)))
1061 		goto ret;
1062 
1063 	pending = group ? &t->signal->shared_pending : &t->pending;
1064 	/*
1065 	 * Short-circuit ignored signals and support queuing
1066 	 * exactly one non-rt signal, so that we can get more
1067 	 * detailed information about the cause of the signal.
1068 	 */
1069 	result = TRACE_SIGNAL_ALREADY_PENDING;
1070 	if (legacy_queue(pending, sig))
1071 		goto ret;
1072 
1073 	result = TRACE_SIGNAL_DELIVERED;
1074 	/*
1075 	 * fast-pathed signals for kernel-internal things like SIGSTOP
1076 	 * or SIGKILL.
1077 	 */
1078 	if (info == SEND_SIG_FORCED)
1079 		goto out_set;
1080 
1081 	/*
1082 	 * Real-time signals must be queued if sent by sigqueue, or
1083 	 * some other real-time mechanism.  It is implementation
1084 	 * defined whether kill() does so.  We attempt to do so, on
1085 	 * the principle of least surprise, but since kill is not
1086 	 * allowed to fail with EAGAIN when low on memory we just
1087 	 * make sure at least one signal gets delivered and don't
1088 	 * pass on the info struct.
1089 	 */
1090 	if (sig < SIGRTMIN)
1091 		override_rlimit = (is_si_special(info) || info->si_code >= 0);
1092 	else
1093 		override_rlimit = 0;
1094 
1095 	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1096 		override_rlimit);
1097 	if (q) {
1098 		list_add_tail(&q->list, &pending->list);
1099 		switch ((unsigned long) info) {
1100 		case (unsigned long) SEND_SIG_NOINFO:
1101 			q->info.si_signo = sig;
1102 			q->info.si_errno = 0;
1103 			q->info.si_code = SI_USER;
1104 			q->info.si_pid = task_tgid_nr_ns(current,
1105 							task_active_pid_ns(t));
1106 			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1107 			break;
1108 		case (unsigned long) SEND_SIG_PRIV:
1109 			q->info.si_signo = sig;
1110 			q->info.si_errno = 0;
1111 			q->info.si_code = SI_KERNEL;
1112 			q->info.si_pid = 0;
1113 			q->info.si_uid = 0;
1114 			break;
1115 		default:
1116 			copy_siginfo(&q->info, info);
1117 			if (from_ancestor_ns)
1118 				q->info.si_pid = 0;
1119 			break;
1120 		}
1121 
1122 		userns_fixup_signal_uid(&q->info, t);
1123 
1124 	} else if (!is_si_special(info)) {
1125 		if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1126 			/*
1127 			 * Queue overflow, abort.  We may abort if the
1128 			 * signal was rt and sent by user using something
1129 			 * other than kill().
1130 			 */
1131 			result = TRACE_SIGNAL_OVERFLOW_FAIL;
1132 			ret = -EAGAIN;
1133 			goto ret;
1134 		} else {
1135 			/*
1136 			 * This is a silent loss of information.  We still
1137 			 * send the signal, but the *info bits are lost.
1138 			 */
1139 			result = TRACE_SIGNAL_LOSE_INFO;
1140 		}
1141 	}
1142 
1143 out_set:
1144 	signalfd_notify(t, sig);
1145 	sigaddset(&pending->signal, sig);
1146 	complete_signal(sig, t, group);
1147 ret:
1148 	trace_signal_generate(sig, info, t, group, result);
1149 	return ret;
1150 }
1151 
1152 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1153 			int group)
1154 {
1155 	int from_ancestor_ns = 0;
1156 
1157 #ifdef CONFIG_PID_NS
1158 	from_ancestor_ns = si_fromuser(info) &&
1159 			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1160 #endif
1161 
1162 	return __send_signal(sig, info, t, group, from_ancestor_ns);
1163 }
1164 
1165 static void print_fatal_signal(int signr)
1166 {
1167 	struct pt_regs *regs = signal_pt_regs();
1168 	printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1169 
1170 #if defined(__i386__) && !defined(__arch_um__)
1171 	printk(KERN_INFO "code at %08lx: ", regs->ip);
1172 	{
1173 		int i;
1174 		for (i = 0; i < 16; i++) {
1175 			unsigned char insn;
1176 
1177 			if (get_user(insn, (unsigned char *)(regs->ip + i)))
1178 				break;
1179 			printk(KERN_CONT "%02x ", insn);
1180 		}
1181 	}
1182 	printk(KERN_CONT "\n");
1183 #endif
1184 	preempt_disable();
1185 	show_regs(regs);
1186 	preempt_enable();
1187 }
1188 
1189 static int __init setup_print_fatal_signals(char *str)
1190 {
1191 	get_option (&str, &print_fatal_signals);
1192 
1193 	return 1;
1194 }
1195 
1196 __setup("print-fatal-signals=", setup_print_fatal_signals);
1197 
1198 int
1199 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1200 {
1201 	return send_signal(sig, info, p, 1);
1202 }
1203 
1204 static int
1205 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1206 {
1207 	return send_signal(sig, info, t, 0);
1208 }
1209 
1210 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1211 			bool group)
1212 {
1213 	unsigned long flags;
1214 	int ret = -ESRCH;
1215 
1216 	if (lock_task_sighand(p, &flags)) {
1217 		ret = send_signal(sig, info, p, group);
1218 		unlock_task_sighand(p, &flags);
1219 	}
1220 
1221 	return ret;
1222 }
1223 
1224 /*
1225  * Force a signal that the process can't ignore: if necessary
1226  * we unblock the signal and change any SIG_IGN to SIG_DFL.
1227  *
1228  * Note: If we unblock the signal, we always reset it to SIG_DFL,
1229  * since we do not want to have a signal handler that was blocked
1230  * be invoked when user space had explicitly blocked it.
1231  *
1232  * We don't want to have recursive SIGSEGV's etc, for example,
1233  * that is why we also clear SIGNAL_UNKILLABLE.
1234  */
1235 int
1236 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1237 {
1238 	unsigned long int flags;
1239 	int ret, blocked, ignored;
1240 	struct k_sigaction *action;
1241 
1242 	spin_lock_irqsave(&t->sighand->siglock, flags);
1243 	action = &t->sighand->action[sig-1];
1244 	ignored = action->sa.sa_handler == SIG_IGN;
1245 	blocked = sigismember(&t->blocked, sig);
1246 	if (blocked || ignored) {
1247 		action->sa.sa_handler = SIG_DFL;
1248 		if (blocked) {
1249 			sigdelset(&t->blocked, sig);
1250 			recalc_sigpending_and_wake(t);
1251 		}
1252 	}
1253 	if (action->sa.sa_handler == SIG_DFL)
1254 		t->signal->flags &= ~SIGNAL_UNKILLABLE;
1255 	ret = specific_send_sig_info(sig, info, t);
1256 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
1257 
1258 	return ret;
1259 }
1260 
1261 /*
1262  * Nuke all other threads in the group.
1263  */
1264 int zap_other_threads(struct task_struct *p)
1265 {
1266 	struct task_struct *t = p;
1267 	int count = 0;
1268 
1269 	p->signal->group_stop_count = 0;
1270 
1271 	while_each_thread(p, t) {
1272 		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1273 		count++;
1274 
1275 		/* Don't bother with already dead threads */
1276 		if (t->exit_state)
1277 			continue;
1278 		sigaddset(&t->pending.signal, SIGKILL);
1279 		signal_wake_up(t, 1);
1280 	}
1281 
1282 	return count;
1283 }
1284 
1285 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1286 					   unsigned long *flags)
1287 {
1288 	struct sighand_struct *sighand;
1289 
1290 	for (;;) {
1291 		local_irq_save(*flags);
1292 		rcu_read_lock();
1293 		sighand = rcu_dereference(tsk->sighand);
1294 		if (unlikely(sighand == NULL)) {
1295 			rcu_read_unlock();
1296 			local_irq_restore(*flags);
1297 			break;
1298 		}
1299 
1300 		spin_lock(&sighand->siglock);
1301 		if (likely(sighand == tsk->sighand)) {
1302 			rcu_read_unlock();
1303 			break;
1304 		}
1305 		spin_unlock(&sighand->siglock);
1306 		rcu_read_unlock();
1307 		local_irq_restore(*flags);
1308 	}
1309 
1310 	return sighand;
1311 }
1312 
1313 /*
1314  * send signal info to all the members of a group
1315  */
1316 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1317 {
1318 	int ret;
1319 
1320 	rcu_read_lock();
1321 	ret = check_kill_permission(sig, info, p);
1322 	rcu_read_unlock();
1323 
1324 	if (!ret && sig)
1325 		ret = do_send_sig_info(sig, info, p, true);
1326 
1327 	return ret;
1328 }
1329 
1330 /*
1331  * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1332  * control characters do (^C, ^Z etc)
1333  * - the caller must hold at least a readlock on tasklist_lock
1334  */
1335 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1336 {
1337 	struct task_struct *p = NULL;
1338 	int retval, success;
1339 
1340 	success = 0;
1341 	retval = -ESRCH;
1342 	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1343 		int err = group_send_sig_info(sig, info, p);
1344 		success |= !err;
1345 		retval = err;
1346 	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1347 	return success ? 0 : retval;
1348 }
1349 
1350 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1351 {
1352 	int error = -ESRCH;
1353 	struct task_struct *p;
1354 
1355 	rcu_read_lock();
1356 retry:
1357 	p = pid_task(pid, PIDTYPE_PID);
1358 	if (p) {
1359 		error = group_send_sig_info(sig, info, p);
1360 		if (unlikely(error == -ESRCH))
1361 			/*
1362 			 * The task was unhashed in between, try again.
1363 			 * If it is dead, pid_task() will return NULL,
1364 			 * if we race with de_thread() it will find the
1365 			 * new leader.
1366 			 */
1367 			goto retry;
1368 	}
1369 	rcu_read_unlock();
1370 
1371 	return error;
1372 }
1373 
1374 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1375 {
1376 	int error;
1377 	rcu_read_lock();
1378 	error = kill_pid_info(sig, info, find_vpid(pid));
1379 	rcu_read_unlock();
1380 	return error;
1381 }
1382 
1383 static int kill_as_cred_perm(const struct cred *cred,
1384 			     struct task_struct *target)
1385 {
1386 	const struct cred *pcred = __task_cred(target);
1387 	if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1388 	    !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
1389 		return 0;
1390 	return 1;
1391 }
1392 
1393 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1394 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1395 			 const struct cred *cred, u32 secid)
1396 {
1397 	int ret = -EINVAL;
1398 	struct task_struct *p;
1399 	unsigned long flags;
1400 
1401 	if (!valid_signal(sig))
1402 		return ret;
1403 
1404 	rcu_read_lock();
1405 	p = pid_task(pid, PIDTYPE_PID);
1406 	if (!p) {
1407 		ret = -ESRCH;
1408 		goto out_unlock;
1409 	}
1410 	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1411 		ret = -EPERM;
1412 		goto out_unlock;
1413 	}
1414 	ret = security_task_kill(p, info, sig, secid);
1415 	if (ret)
1416 		goto out_unlock;
1417 
1418 	if (sig) {
1419 		if (lock_task_sighand(p, &flags)) {
1420 			ret = __send_signal(sig, info, p, 1, 0);
1421 			unlock_task_sighand(p, &flags);
1422 		} else
1423 			ret = -ESRCH;
1424 	}
1425 out_unlock:
1426 	rcu_read_unlock();
1427 	return ret;
1428 }
1429 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1430 
1431 /*
1432  * kill_something_info() interprets pid in interesting ways just like kill(2).
1433  *
1434  * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1435  * is probably wrong.  Should make it like BSD or SYSV.
1436  */
1437 
1438 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1439 {
1440 	int ret;
1441 
1442 	if (pid > 0) {
1443 		rcu_read_lock();
1444 		ret = kill_pid_info(sig, info, find_vpid(pid));
1445 		rcu_read_unlock();
1446 		return ret;
1447 	}
1448 
1449 	read_lock(&tasklist_lock);
1450 	if (pid != -1) {
1451 		ret = __kill_pgrp_info(sig, info,
1452 				pid ? find_vpid(-pid) : task_pgrp(current));
1453 	} else {
1454 		int retval = 0, count = 0;
1455 		struct task_struct * p;
1456 
1457 		for_each_process(p) {
1458 			if (task_pid_vnr(p) > 1 &&
1459 					!same_thread_group(p, current)) {
1460 				int err = group_send_sig_info(sig, info, p);
1461 				++count;
1462 				if (err != -EPERM)
1463 					retval = err;
1464 			}
1465 		}
1466 		ret = count ? retval : -ESRCH;
1467 	}
1468 	read_unlock(&tasklist_lock);
1469 
1470 	return ret;
1471 }
1472 
1473 /*
1474  * These are for backward compatibility with the rest of the kernel source.
1475  */
1476 
1477 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1478 {
1479 	/*
1480 	 * Make sure legacy kernel users don't send in bad values
1481 	 * (normal paths check this in check_kill_permission).
1482 	 */
1483 	if (!valid_signal(sig))
1484 		return -EINVAL;
1485 
1486 	return do_send_sig_info(sig, info, p, false);
1487 }
1488 
1489 #define __si_special(priv) \
1490 	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1491 
1492 int
1493 send_sig(int sig, struct task_struct *p, int priv)
1494 {
1495 	return send_sig_info(sig, __si_special(priv), p);
1496 }
1497 
1498 void
1499 force_sig(int sig, struct task_struct *p)
1500 {
1501 	force_sig_info(sig, SEND_SIG_PRIV, p);
1502 }
1503 
1504 /*
1505  * When things go south during signal handling, we
1506  * will force a SIGSEGV. And if the signal that caused
1507  * the problem was already a SIGSEGV, we'll want to
1508  * make sure we don't even try to deliver the signal..
1509  */
1510 int
1511 force_sigsegv(int sig, struct task_struct *p)
1512 {
1513 	if (sig == SIGSEGV) {
1514 		unsigned long flags;
1515 		spin_lock_irqsave(&p->sighand->siglock, flags);
1516 		p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1517 		spin_unlock_irqrestore(&p->sighand->siglock, flags);
1518 	}
1519 	force_sig(SIGSEGV, p);
1520 	return 0;
1521 }
1522 
1523 int kill_pgrp(struct pid *pid, int sig, int priv)
1524 {
1525 	int ret;
1526 
1527 	read_lock(&tasklist_lock);
1528 	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1529 	read_unlock(&tasklist_lock);
1530 
1531 	return ret;
1532 }
1533 EXPORT_SYMBOL(kill_pgrp);
1534 
1535 int kill_pid(struct pid *pid, int sig, int priv)
1536 {
1537 	return kill_pid_info(sig, __si_special(priv), pid);
1538 }
1539 EXPORT_SYMBOL(kill_pid);
1540 
1541 /*
1542  * These functions support sending signals using preallocated sigqueue
1543  * structures.  This is needed "because realtime applications cannot
1544  * afford to lose notifications of asynchronous events, like timer
1545  * expirations or I/O completions".  In the case of POSIX Timers
1546  * we allocate the sigqueue structure from the timer_create.  If this
1547  * allocation fails we are able to report the failure to the application
1548  * with an EAGAIN error.
1549  */
1550 struct sigqueue *sigqueue_alloc(void)
1551 {
1552 	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1553 
1554 	if (q)
1555 		q->flags |= SIGQUEUE_PREALLOC;
1556 
1557 	return q;
1558 }
1559 
1560 void sigqueue_free(struct sigqueue *q)
1561 {
1562 	unsigned long flags;
1563 	spinlock_t *lock = &current->sighand->siglock;
1564 
1565 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1566 	/*
1567 	 * We must hold ->siglock while testing q->list
1568 	 * to serialize with collect_signal() or with
1569 	 * __exit_signal()->flush_sigqueue().
1570 	 */
1571 	spin_lock_irqsave(lock, flags);
1572 	q->flags &= ~SIGQUEUE_PREALLOC;
1573 	/*
1574 	 * If it is queued it will be freed when dequeued,
1575 	 * like the "regular" sigqueue.
1576 	 */
1577 	if (!list_empty(&q->list))
1578 		q = NULL;
1579 	spin_unlock_irqrestore(lock, flags);
1580 
1581 	if (q)
1582 		__sigqueue_free(q);
1583 }
1584 
1585 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1586 {
1587 	int sig = q->info.si_signo;
1588 	struct sigpending *pending;
1589 	unsigned long flags;
1590 	int ret, result;
1591 
1592 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1593 
1594 	ret = -1;
1595 	if (!likely(lock_task_sighand(t, &flags)))
1596 		goto ret;
1597 
1598 	ret = 1; /* the signal is ignored */
1599 	result = TRACE_SIGNAL_IGNORED;
1600 	if (!prepare_signal(sig, t, false))
1601 		goto out;
1602 
1603 	ret = 0;
1604 	if (unlikely(!list_empty(&q->list))) {
1605 		/*
1606 		 * If an SI_TIMER entry is already queue just increment
1607 		 * the overrun count.
1608 		 */
1609 		BUG_ON(q->info.si_code != SI_TIMER);
1610 		q->info.si_overrun++;
1611 		result = TRACE_SIGNAL_ALREADY_PENDING;
1612 		goto out;
1613 	}
1614 	q->info.si_overrun = 0;
1615 
1616 	signalfd_notify(t, sig);
1617 	pending = group ? &t->signal->shared_pending : &t->pending;
1618 	list_add_tail(&q->list, &pending->list);
1619 	sigaddset(&pending->signal, sig);
1620 	complete_signal(sig, t, group);
1621 	result = TRACE_SIGNAL_DELIVERED;
1622 out:
1623 	trace_signal_generate(sig, &q->info, t, group, result);
1624 	unlock_task_sighand(t, &flags);
1625 ret:
1626 	return ret;
1627 }
1628 
1629 /*
1630  * Let a parent know about the death of a child.
1631  * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1632  *
1633  * Returns true if our parent ignored us and so we've switched to
1634  * self-reaping.
1635  */
1636 bool do_notify_parent(struct task_struct *tsk, int sig)
1637 {
1638 	struct siginfo info;
1639 	unsigned long flags;
1640 	struct sighand_struct *psig;
1641 	bool autoreap = false;
1642 	cputime_t utime, stime;
1643 
1644 	BUG_ON(sig == -1);
1645 
1646  	/* do_notify_parent_cldstop should have been called instead.  */
1647  	BUG_ON(task_is_stopped_or_traced(tsk));
1648 
1649 	BUG_ON(!tsk->ptrace &&
1650 	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1651 
1652 	if (sig != SIGCHLD) {
1653 		/*
1654 		 * This is only possible if parent == real_parent.
1655 		 * Check if it has changed security domain.
1656 		 */
1657 		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1658 			sig = SIGCHLD;
1659 	}
1660 
1661 	info.si_signo = sig;
1662 	info.si_errno = 0;
1663 	/*
1664 	 * We are under tasklist_lock here so our parent is tied to
1665 	 * us and cannot change.
1666 	 *
1667 	 * task_active_pid_ns will always return the same pid namespace
1668 	 * until a task passes through release_task.
1669 	 *
1670 	 * write_lock() currently calls preempt_disable() which is the
1671 	 * same as rcu_read_lock(), but according to Oleg, this is not
1672 	 * correct to rely on this
1673 	 */
1674 	rcu_read_lock();
1675 	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1676 	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1677 				       task_uid(tsk));
1678 	rcu_read_unlock();
1679 
1680 	task_cputime(tsk, &utime, &stime);
1681 	info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1682 	info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1683 
1684 	info.si_status = tsk->exit_code & 0x7f;
1685 	if (tsk->exit_code & 0x80)
1686 		info.si_code = CLD_DUMPED;
1687 	else if (tsk->exit_code & 0x7f)
1688 		info.si_code = CLD_KILLED;
1689 	else {
1690 		info.si_code = CLD_EXITED;
1691 		info.si_status = tsk->exit_code >> 8;
1692 	}
1693 
1694 	psig = tsk->parent->sighand;
1695 	spin_lock_irqsave(&psig->siglock, flags);
1696 	if (!tsk->ptrace && sig == SIGCHLD &&
1697 	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1698 	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1699 		/*
1700 		 * We are exiting and our parent doesn't care.  POSIX.1
1701 		 * defines special semantics for setting SIGCHLD to SIG_IGN
1702 		 * or setting the SA_NOCLDWAIT flag: we should be reaped
1703 		 * automatically and not left for our parent's wait4 call.
1704 		 * Rather than having the parent do it as a magic kind of
1705 		 * signal handler, we just set this to tell do_exit that we
1706 		 * can be cleaned up without becoming a zombie.  Note that
1707 		 * we still call __wake_up_parent in this case, because a
1708 		 * blocked sys_wait4 might now return -ECHILD.
1709 		 *
1710 		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1711 		 * is implementation-defined: we do (if you don't want
1712 		 * it, just use SIG_IGN instead).
1713 		 */
1714 		autoreap = true;
1715 		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1716 			sig = 0;
1717 	}
1718 	if (valid_signal(sig) && sig)
1719 		__group_send_sig_info(sig, &info, tsk->parent);
1720 	__wake_up_parent(tsk, tsk->parent);
1721 	spin_unlock_irqrestore(&psig->siglock, flags);
1722 
1723 	return autoreap;
1724 }
1725 
1726 /**
1727  * do_notify_parent_cldstop - notify parent of stopped/continued state change
1728  * @tsk: task reporting the state change
1729  * @for_ptracer: the notification is for ptracer
1730  * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1731  *
1732  * Notify @tsk's parent that the stopped/continued state has changed.  If
1733  * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1734  * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1735  *
1736  * CONTEXT:
1737  * Must be called with tasklist_lock at least read locked.
1738  */
1739 static void do_notify_parent_cldstop(struct task_struct *tsk,
1740 				     bool for_ptracer, int why)
1741 {
1742 	struct siginfo info;
1743 	unsigned long flags;
1744 	struct task_struct *parent;
1745 	struct sighand_struct *sighand;
1746 	cputime_t utime, stime;
1747 
1748 	if (for_ptracer) {
1749 		parent = tsk->parent;
1750 	} else {
1751 		tsk = tsk->group_leader;
1752 		parent = tsk->real_parent;
1753 	}
1754 
1755 	info.si_signo = SIGCHLD;
1756 	info.si_errno = 0;
1757 	/*
1758 	 * see comment in do_notify_parent() about the following 4 lines
1759 	 */
1760 	rcu_read_lock();
1761 	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1762 	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1763 	rcu_read_unlock();
1764 
1765 	task_cputime(tsk, &utime, &stime);
1766 	info.si_utime = cputime_to_clock_t(utime);
1767 	info.si_stime = cputime_to_clock_t(stime);
1768 
1769  	info.si_code = why;
1770  	switch (why) {
1771  	case CLD_CONTINUED:
1772  		info.si_status = SIGCONT;
1773  		break;
1774  	case CLD_STOPPED:
1775  		info.si_status = tsk->signal->group_exit_code & 0x7f;
1776  		break;
1777  	case CLD_TRAPPED:
1778  		info.si_status = tsk->exit_code & 0x7f;
1779  		break;
1780  	default:
1781  		BUG();
1782  	}
1783 
1784 	sighand = parent->sighand;
1785 	spin_lock_irqsave(&sighand->siglock, flags);
1786 	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1787 	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1788 		__group_send_sig_info(SIGCHLD, &info, parent);
1789 	/*
1790 	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1791 	 */
1792 	__wake_up_parent(tsk, parent);
1793 	spin_unlock_irqrestore(&sighand->siglock, flags);
1794 }
1795 
1796 static inline int may_ptrace_stop(void)
1797 {
1798 	if (!likely(current->ptrace))
1799 		return 0;
1800 	/*
1801 	 * Are we in the middle of do_coredump?
1802 	 * If so and our tracer is also part of the coredump stopping
1803 	 * is a deadlock situation, and pointless because our tracer
1804 	 * is dead so don't allow us to stop.
1805 	 * If SIGKILL was already sent before the caller unlocked
1806 	 * ->siglock we must see ->core_state != NULL. Otherwise it
1807 	 * is safe to enter schedule().
1808 	 *
1809 	 * This is almost outdated, a task with the pending SIGKILL can't
1810 	 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1811 	 * after SIGKILL was already dequeued.
1812 	 */
1813 	if (unlikely(current->mm->core_state) &&
1814 	    unlikely(current->mm == current->parent->mm))
1815 		return 0;
1816 
1817 	return 1;
1818 }
1819 
1820 /*
1821  * Return non-zero if there is a SIGKILL that should be waking us up.
1822  * Called with the siglock held.
1823  */
1824 static int sigkill_pending(struct task_struct *tsk)
1825 {
1826 	return	sigismember(&tsk->pending.signal, SIGKILL) ||
1827 		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1828 }
1829 
1830 /*
1831  * This must be called with current->sighand->siglock held.
1832  *
1833  * This should be the path for all ptrace stops.
1834  * We always set current->last_siginfo while stopped here.
1835  * That makes it a way to test a stopped process for
1836  * being ptrace-stopped vs being job-control-stopped.
1837  *
1838  * If we actually decide not to stop at all because the tracer
1839  * is gone, we keep current->exit_code unless clear_code.
1840  */
1841 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1842 	__releases(&current->sighand->siglock)
1843 	__acquires(&current->sighand->siglock)
1844 {
1845 	bool gstop_done = false;
1846 
1847 	if (arch_ptrace_stop_needed(exit_code, info)) {
1848 		/*
1849 		 * The arch code has something special to do before a
1850 		 * ptrace stop.  This is allowed to block, e.g. for faults
1851 		 * on user stack pages.  We can't keep the siglock while
1852 		 * calling arch_ptrace_stop, so we must release it now.
1853 		 * To preserve proper semantics, we must do this before
1854 		 * any signal bookkeeping like checking group_stop_count.
1855 		 * Meanwhile, a SIGKILL could come in before we retake the
1856 		 * siglock.  That must prevent us from sleeping in TASK_TRACED.
1857 		 * So after regaining the lock, we must check for SIGKILL.
1858 		 */
1859 		spin_unlock_irq(&current->sighand->siglock);
1860 		arch_ptrace_stop(exit_code, info);
1861 		spin_lock_irq(&current->sighand->siglock);
1862 		if (sigkill_pending(current))
1863 			return;
1864 	}
1865 
1866 	/*
1867 	 * We're committing to trapping.  TRACED should be visible before
1868 	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1869 	 * Also, transition to TRACED and updates to ->jobctl should be
1870 	 * atomic with respect to siglock and should be done after the arch
1871 	 * hook as siglock is released and regrabbed across it.
1872 	 */
1873 	set_current_state(TASK_TRACED);
1874 
1875 	current->last_siginfo = info;
1876 	current->exit_code = exit_code;
1877 
1878 	/*
1879 	 * If @why is CLD_STOPPED, we're trapping to participate in a group
1880 	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1881 	 * across siglock relocks since INTERRUPT was scheduled, PENDING
1882 	 * could be clear now.  We act as if SIGCONT is received after
1883 	 * TASK_TRACED is entered - ignore it.
1884 	 */
1885 	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1886 		gstop_done = task_participate_group_stop(current);
1887 
1888 	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1889 	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1890 	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1891 		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1892 
1893 	/* entering a trap, clear TRAPPING */
1894 	task_clear_jobctl_trapping(current);
1895 
1896 	spin_unlock_irq(&current->sighand->siglock);
1897 	read_lock(&tasklist_lock);
1898 	if (may_ptrace_stop()) {
1899 		/*
1900 		 * Notify parents of the stop.
1901 		 *
1902 		 * While ptraced, there are two parents - the ptracer and
1903 		 * the real_parent of the group_leader.  The ptracer should
1904 		 * know about every stop while the real parent is only
1905 		 * interested in the completion of group stop.  The states
1906 		 * for the two don't interact with each other.  Notify
1907 		 * separately unless they're gonna be duplicates.
1908 		 */
1909 		do_notify_parent_cldstop(current, true, why);
1910 		if (gstop_done && ptrace_reparented(current))
1911 			do_notify_parent_cldstop(current, false, why);
1912 
1913 		/*
1914 		 * Don't want to allow preemption here, because
1915 		 * sys_ptrace() needs this task to be inactive.
1916 		 *
1917 		 * XXX: implement read_unlock_no_resched().
1918 		 */
1919 		preempt_disable();
1920 		read_unlock(&tasklist_lock);
1921 		preempt_enable_no_resched();
1922 		freezable_schedule();
1923 	} else {
1924 		/*
1925 		 * By the time we got the lock, our tracer went away.
1926 		 * Don't drop the lock yet, another tracer may come.
1927 		 *
1928 		 * If @gstop_done, the ptracer went away between group stop
1929 		 * completion and here.  During detach, it would have set
1930 		 * JOBCTL_STOP_PENDING on us and we'll re-enter
1931 		 * TASK_STOPPED in do_signal_stop() on return, so notifying
1932 		 * the real parent of the group stop completion is enough.
1933 		 */
1934 		if (gstop_done)
1935 			do_notify_parent_cldstop(current, false, why);
1936 
1937 		/* tasklist protects us from ptrace_freeze_traced() */
1938 		__set_current_state(TASK_RUNNING);
1939 		if (clear_code)
1940 			current->exit_code = 0;
1941 		read_unlock(&tasklist_lock);
1942 	}
1943 
1944 	/*
1945 	 * We are back.  Now reacquire the siglock before touching
1946 	 * last_siginfo, so that we are sure to have synchronized with
1947 	 * any signal-sending on another CPU that wants to examine it.
1948 	 */
1949 	spin_lock_irq(&current->sighand->siglock);
1950 	current->last_siginfo = NULL;
1951 
1952 	/* LISTENING can be set only during STOP traps, clear it */
1953 	current->jobctl &= ~JOBCTL_LISTENING;
1954 
1955 	/*
1956 	 * Queued signals ignored us while we were stopped for tracing.
1957 	 * So check for any that we should take before resuming user mode.
1958 	 * This sets TIF_SIGPENDING, but never clears it.
1959 	 */
1960 	recalc_sigpending_tsk(current);
1961 }
1962 
1963 static void ptrace_do_notify(int signr, int exit_code, int why)
1964 {
1965 	siginfo_t info;
1966 
1967 	memset(&info, 0, sizeof info);
1968 	info.si_signo = signr;
1969 	info.si_code = exit_code;
1970 	info.si_pid = task_pid_vnr(current);
1971 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1972 
1973 	/* Let the debugger run.  */
1974 	ptrace_stop(exit_code, why, 1, &info);
1975 }
1976 
1977 void ptrace_notify(int exit_code)
1978 {
1979 	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1980 	if (unlikely(current->task_works))
1981 		task_work_run();
1982 
1983 	spin_lock_irq(&current->sighand->siglock);
1984 	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1985 	spin_unlock_irq(&current->sighand->siglock);
1986 }
1987 
1988 /**
1989  * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1990  * @signr: signr causing group stop if initiating
1991  *
1992  * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1993  * and participate in it.  If already set, participate in the existing
1994  * group stop.  If participated in a group stop (and thus slept), %true is
1995  * returned with siglock released.
1996  *
1997  * If ptraced, this function doesn't handle stop itself.  Instead,
1998  * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1999  * untouched.  The caller must ensure that INTERRUPT trap handling takes
2000  * places afterwards.
2001  *
2002  * CONTEXT:
2003  * Must be called with @current->sighand->siglock held, which is released
2004  * on %true return.
2005  *
2006  * RETURNS:
2007  * %false if group stop is already cancelled or ptrace trap is scheduled.
2008  * %true if participated in group stop.
2009  */
2010 static bool do_signal_stop(int signr)
2011 	__releases(&current->sighand->siglock)
2012 {
2013 	struct signal_struct *sig = current->signal;
2014 
2015 	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2016 		unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2017 		struct task_struct *t;
2018 
2019 		/* signr will be recorded in task->jobctl for retries */
2020 		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2021 
2022 		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2023 		    unlikely(signal_group_exit(sig)))
2024 			return false;
2025 		/*
2026 		 * There is no group stop already in progress.  We must
2027 		 * initiate one now.
2028 		 *
2029 		 * While ptraced, a task may be resumed while group stop is
2030 		 * still in effect and then receive a stop signal and
2031 		 * initiate another group stop.  This deviates from the
2032 		 * usual behavior as two consecutive stop signals can't
2033 		 * cause two group stops when !ptraced.  That is why we
2034 		 * also check !task_is_stopped(t) below.
2035 		 *
2036 		 * The condition can be distinguished by testing whether
2037 		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
2038 		 * group_exit_code in such case.
2039 		 *
2040 		 * This is not necessary for SIGNAL_STOP_CONTINUED because
2041 		 * an intervening stop signal is required to cause two
2042 		 * continued events regardless of ptrace.
2043 		 */
2044 		if (!(sig->flags & SIGNAL_STOP_STOPPED))
2045 			sig->group_exit_code = signr;
2046 
2047 		sig->group_stop_count = 0;
2048 
2049 		if (task_set_jobctl_pending(current, signr | gstop))
2050 			sig->group_stop_count++;
2051 
2052 		t = current;
2053 		while_each_thread(current, t) {
2054 			/*
2055 			 * Setting state to TASK_STOPPED for a group
2056 			 * stop is always done with the siglock held,
2057 			 * so this check has no races.
2058 			 */
2059 			if (!task_is_stopped(t) &&
2060 			    task_set_jobctl_pending(t, signr | gstop)) {
2061 				sig->group_stop_count++;
2062 				if (likely(!(t->ptrace & PT_SEIZED)))
2063 					signal_wake_up(t, 0);
2064 				else
2065 					ptrace_trap_notify(t);
2066 			}
2067 		}
2068 	}
2069 
2070 	if (likely(!current->ptrace)) {
2071 		int notify = 0;
2072 
2073 		/*
2074 		 * If there are no other threads in the group, or if there
2075 		 * is a group stop in progress and we are the last to stop,
2076 		 * report to the parent.
2077 		 */
2078 		if (task_participate_group_stop(current))
2079 			notify = CLD_STOPPED;
2080 
2081 		__set_current_state(TASK_STOPPED);
2082 		spin_unlock_irq(&current->sighand->siglock);
2083 
2084 		/*
2085 		 * Notify the parent of the group stop completion.  Because
2086 		 * we're not holding either the siglock or tasklist_lock
2087 		 * here, ptracer may attach inbetween; however, this is for
2088 		 * group stop and should always be delivered to the real
2089 		 * parent of the group leader.  The new ptracer will get
2090 		 * its notification when this task transitions into
2091 		 * TASK_TRACED.
2092 		 */
2093 		if (notify) {
2094 			read_lock(&tasklist_lock);
2095 			do_notify_parent_cldstop(current, false, notify);
2096 			read_unlock(&tasklist_lock);
2097 		}
2098 
2099 		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2100 		freezable_schedule();
2101 		return true;
2102 	} else {
2103 		/*
2104 		 * While ptraced, group stop is handled by STOP trap.
2105 		 * Schedule it and let the caller deal with it.
2106 		 */
2107 		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2108 		return false;
2109 	}
2110 }
2111 
2112 /**
2113  * do_jobctl_trap - take care of ptrace jobctl traps
2114  *
2115  * When PT_SEIZED, it's used for both group stop and explicit
2116  * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
2117  * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
2118  * the stop signal; otherwise, %SIGTRAP.
2119  *
2120  * When !PT_SEIZED, it's used only for group stop trap with stop signal
2121  * number as exit_code and no siginfo.
2122  *
2123  * CONTEXT:
2124  * Must be called with @current->sighand->siglock held, which may be
2125  * released and re-acquired before returning with intervening sleep.
2126  */
2127 static void do_jobctl_trap(void)
2128 {
2129 	struct signal_struct *signal = current->signal;
2130 	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2131 
2132 	if (current->ptrace & PT_SEIZED) {
2133 		if (!signal->group_stop_count &&
2134 		    !(signal->flags & SIGNAL_STOP_STOPPED))
2135 			signr = SIGTRAP;
2136 		WARN_ON_ONCE(!signr);
2137 		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2138 				 CLD_STOPPED);
2139 	} else {
2140 		WARN_ON_ONCE(!signr);
2141 		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2142 		current->exit_code = 0;
2143 	}
2144 }
2145 
2146 static int ptrace_signal(int signr, siginfo_t *info)
2147 {
2148 	ptrace_signal_deliver();
2149 	/*
2150 	 * We do not check sig_kernel_stop(signr) but set this marker
2151 	 * unconditionally because we do not know whether debugger will
2152 	 * change signr. This flag has no meaning unless we are going
2153 	 * to stop after return from ptrace_stop(). In this case it will
2154 	 * be checked in do_signal_stop(), we should only stop if it was
2155 	 * not cleared by SIGCONT while we were sleeping. See also the
2156 	 * comment in dequeue_signal().
2157 	 */
2158 	current->jobctl |= JOBCTL_STOP_DEQUEUED;
2159 	ptrace_stop(signr, CLD_TRAPPED, 0, info);
2160 
2161 	/* We're back.  Did the debugger cancel the sig?  */
2162 	signr = current->exit_code;
2163 	if (signr == 0)
2164 		return signr;
2165 
2166 	current->exit_code = 0;
2167 
2168 	/*
2169 	 * Update the siginfo structure if the signal has
2170 	 * changed.  If the debugger wanted something
2171 	 * specific in the siginfo structure then it should
2172 	 * have updated *info via PTRACE_SETSIGINFO.
2173 	 */
2174 	if (signr != info->si_signo) {
2175 		info->si_signo = signr;
2176 		info->si_errno = 0;
2177 		info->si_code = SI_USER;
2178 		rcu_read_lock();
2179 		info->si_pid = task_pid_vnr(current->parent);
2180 		info->si_uid = from_kuid_munged(current_user_ns(),
2181 						task_uid(current->parent));
2182 		rcu_read_unlock();
2183 	}
2184 
2185 	/* If the (new) signal is now blocked, requeue it.  */
2186 	if (sigismember(&current->blocked, signr)) {
2187 		specific_send_sig_info(signr, info, current);
2188 		signr = 0;
2189 	}
2190 
2191 	return signr;
2192 }
2193 
2194 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2195 			  struct pt_regs *regs, void *cookie)
2196 {
2197 	struct sighand_struct *sighand = current->sighand;
2198 	struct signal_struct *signal = current->signal;
2199 	int signr;
2200 
2201 	if (unlikely(current->task_works))
2202 		task_work_run();
2203 
2204 	if (unlikely(uprobe_deny_signal()))
2205 		return 0;
2206 
2207 	/*
2208 	 * Do this once, we can't return to user-mode if freezing() == T.
2209 	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2210 	 * thus do not need another check after return.
2211 	 */
2212 	try_to_freeze();
2213 
2214 relock:
2215 	spin_lock_irq(&sighand->siglock);
2216 	/*
2217 	 * Every stopped thread goes here after wakeup. Check to see if
2218 	 * we should notify the parent, prepare_signal(SIGCONT) encodes
2219 	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2220 	 */
2221 	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2222 		int why;
2223 
2224 		if (signal->flags & SIGNAL_CLD_CONTINUED)
2225 			why = CLD_CONTINUED;
2226 		else
2227 			why = CLD_STOPPED;
2228 
2229 		signal->flags &= ~SIGNAL_CLD_MASK;
2230 
2231 		spin_unlock_irq(&sighand->siglock);
2232 
2233 		/*
2234 		 * Notify the parent that we're continuing.  This event is
2235 		 * always per-process and doesn't make whole lot of sense
2236 		 * for ptracers, who shouldn't consume the state via
2237 		 * wait(2) either, but, for backward compatibility, notify
2238 		 * the ptracer of the group leader too unless it's gonna be
2239 		 * a duplicate.
2240 		 */
2241 		read_lock(&tasklist_lock);
2242 		do_notify_parent_cldstop(current, false, why);
2243 
2244 		if (ptrace_reparented(current->group_leader))
2245 			do_notify_parent_cldstop(current->group_leader,
2246 						true, why);
2247 		read_unlock(&tasklist_lock);
2248 
2249 		goto relock;
2250 	}
2251 
2252 	for (;;) {
2253 		struct k_sigaction *ka;
2254 
2255 		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2256 		    do_signal_stop(0))
2257 			goto relock;
2258 
2259 		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2260 			do_jobctl_trap();
2261 			spin_unlock_irq(&sighand->siglock);
2262 			goto relock;
2263 		}
2264 
2265 		signr = dequeue_signal(current, &current->blocked, info);
2266 
2267 		if (!signr)
2268 			break; /* will return 0 */
2269 
2270 		if (unlikely(current->ptrace) && signr != SIGKILL) {
2271 			signr = ptrace_signal(signr, info);
2272 			if (!signr)
2273 				continue;
2274 		}
2275 
2276 		ka = &sighand->action[signr-1];
2277 
2278 		/* Trace actually delivered signals. */
2279 		trace_signal_deliver(signr, info, ka);
2280 
2281 		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
2282 			continue;
2283 		if (ka->sa.sa_handler != SIG_DFL) {
2284 			/* Run the handler.  */
2285 			*return_ka = *ka;
2286 
2287 			if (ka->sa.sa_flags & SA_ONESHOT)
2288 				ka->sa.sa_handler = SIG_DFL;
2289 
2290 			break; /* will return non-zero "signr" value */
2291 		}
2292 
2293 		/*
2294 		 * Now we are doing the default action for this signal.
2295 		 */
2296 		if (sig_kernel_ignore(signr)) /* Default is nothing. */
2297 			continue;
2298 
2299 		/*
2300 		 * Global init gets no signals it doesn't want.
2301 		 * Container-init gets no signals it doesn't want from same
2302 		 * container.
2303 		 *
2304 		 * Note that if global/container-init sees a sig_kernel_only()
2305 		 * signal here, the signal must have been generated internally
2306 		 * or must have come from an ancestor namespace. In either
2307 		 * case, the signal cannot be dropped.
2308 		 */
2309 		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2310 				!sig_kernel_only(signr))
2311 			continue;
2312 
2313 		if (sig_kernel_stop(signr)) {
2314 			/*
2315 			 * The default action is to stop all threads in
2316 			 * the thread group.  The job control signals
2317 			 * do nothing in an orphaned pgrp, but SIGSTOP
2318 			 * always works.  Note that siglock needs to be
2319 			 * dropped during the call to is_orphaned_pgrp()
2320 			 * because of lock ordering with tasklist_lock.
2321 			 * This allows an intervening SIGCONT to be posted.
2322 			 * We need to check for that and bail out if necessary.
2323 			 */
2324 			if (signr != SIGSTOP) {
2325 				spin_unlock_irq(&sighand->siglock);
2326 
2327 				/* signals can be posted during this window */
2328 
2329 				if (is_current_pgrp_orphaned())
2330 					goto relock;
2331 
2332 				spin_lock_irq(&sighand->siglock);
2333 			}
2334 
2335 			if (likely(do_signal_stop(info->si_signo))) {
2336 				/* It released the siglock.  */
2337 				goto relock;
2338 			}
2339 
2340 			/*
2341 			 * We didn't actually stop, due to a race
2342 			 * with SIGCONT or something like that.
2343 			 */
2344 			continue;
2345 		}
2346 
2347 		spin_unlock_irq(&sighand->siglock);
2348 
2349 		/*
2350 		 * Anything else is fatal, maybe with a core dump.
2351 		 */
2352 		current->flags |= PF_SIGNALED;
2353 
2354 		if (sig_kernel_coredump(signr)) {
2355 			if (print_fatal_signals)
2356 				print_fatal_signal(info->si_signo);
2357 			proc_coredump_connector(current);
2358 			/*
2359 			 * If it was able to dump core, this kills all
2360 			 * other threads in the group and synchronizes with
2361 			 * their demise.  If we lost the race with another
2362 			 * thread getting here, it set group_exit_code
2363 			 * first and our do_group_exit call below will use
2364 			 * that value and ignore the one we pass it.
2365 			 */
2366 			do_coredump(info);
2367 		}
2368 
2369 		/*
2370 		 * Death signals, no core dump.
2371 		 */
2372 		do_group_exit(info->si_signo);
2373 		/* NOTREACHED */
2374 	}
2375 	spin_unlock_irq(&sighand->siglock);
2376 	return signr;
2377 }
2378 
2379 /**
2380  * signal_delivered -
2381  * @sig:		number of signal being delivered
2382  * @info:		siginfo_t of signal being delivered
2383  * @ka:			sigaction setting that chose the handler
2384  * @regs:		user register state
2385  * @stepping:		nonzero if debugger single-step or block-step in use
2386  *
2387  * This function should be called when a signal has successfully been
2388  * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2389  * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2390  * is set in @ka->sa.sa_flags.  Tracing is notified.
2391  */
2392 void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2393 			struct pt_regs *regs, int stepping)
2394 {
2395 	sigset_t blocked;
2396 
2397 	/* A signal was successfully delivered, and the
2398 	   saved sigmask was stored on the signal frame,
2399 	   and will be restored by sigreturn.  So we can
2400 	   simply clear the restore sigmask flag.  */
2401 	clear_restore_sigmask();
2402 
2403 	sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
2404 	if (!(ka->sa.sa_flags & SA_NODEFER))
2405 		sigaddset(&blocked, sig);
2406 	set_current_blocked(&blocked);
2407 	tracehook_signal_handler(sig, info, ka, regs, stepping);
2408 }
2409 
2410 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2411 {
2412 	if (failed)
2413 		force_sigsegv(ksig->sig, current);
2414 	else
2415 		signal_delivered(ksig->sig, &ksig->info, &ksig->ka,
2416 			signal_pt_regs(), stepping);
2417 }
2418 
2419 /*
2420  * It could be that complete_signal() picked us to notify about the
2421  * group-wide signal. Other threads should be notified now to take
2422  * the shared signals in @which since we will not.
2423  */
2424 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2425 {
2426 	sigset_t retarget;
2427 	struct task_struct *t;
2428 
2429 	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2430 	if (sigisemptyset(&retarget))
2431 		return;
2432 
2433 	t = tsk;
2434 	while_each_thread(tsk, t) {
2435 		if (t->flags & PF_EXITING)
2436 			continue;
2437 
2438 		if (!has_pending_signals(&retarget, &t->blocked))
2439 			continue;
2440 		/* Remove the signals this thread can handle. */
2441 		sigandsets(&retarget, &retarget, &t->blocked);
2442 
2443 		if (!signal_pending(t))
2444 			signal_wake_up(t, 0);
2445 
2446 		if (sigisemptyset(&retarget))
2447 			break;
2448 	}
2449 }
2450 
2451 void exit_signals(struct task_struct *tsk)
2452 {
2453 	int group_stop = 0;
2454 	sigset_t unblocked;
2455 
2456 	/*
2457 	 * @tsk is about to have PF_EXITING set - lock out users which
2458 	 * expect stable threadgroup.
2459 	 */
2460 	threadgroup_change_begin(tsk);
2461 
2462 	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2463 		tsk->flags |= PF_EXITING;
2464 		threadgroup_change_end(tsk);
2465 		return;
2466 	}
2467 
2468 	spin_lock_irq(&tsk->sighand->siglock);
2469 	/*
2470 	 * From now this task is not visible for group-wide signals,
2471 	 * see wants_signal(), do_signal_stop().
2472 	 */
2473 	tsk->flags |= PF_EXITING;
2474 
2475 	threadgroup_change_end(tsk);
2476 
2477 	if (!signal_pending(tsk))
2478 		goto out;
2479 
2480 	unblocked = tsk->blocked;
2481 	signotset(&unblocked);
2482 	retarget_shared_pending(tsk, &unblocked);
2483 
2484 	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2485 	    task_participate_group_stop(tsk))
2486 		group_stop = CLD_STOPPED;
2487 out:
2488 	spin_unlock_irq(&tsk->sighand->siglock);
2489 
2490 	/*
2491 	 * If group stop has completed, deliver the notification.  This
2492 	 * should always go to the real parent of the group leader.
2493 	 */
2494 	if (unlikely(group_stop)) {
2495 		read_lock(&tasklist_lock);
2496 		do_notify_parent_cldstop(tsk, false, group_stop);
2497 		read_unlock(&tasklist_lock);
2498 	}
2499 }
2500 
2501 EXPORT_SYMBOL(recalc_sigpending);
2502 EXPORT_SYMBOL_GPL(dequeue_signal);
2503 EXPORT_SYMBOL(flush_signals);
2504 EXPORT_SYMBOL(force_sig);
2505 EXPORT_SYMBOL(send_sig);
2506 EXPORT_SYMBOL(send_sig_info);
2507 EXPORT_SYMBOL(sigprocmask);
2508 EXPORT_SYMBOL(block_all_signals);
2509 EXPORT_SYMBOL(unblock_all_signals);
2510 
2511 
2512 /*
2513  * System call entry points.
2514  */
2515 
2516 /**
2517  *  sys_restart_syscall - restart a system call
2518  */
2519 SYSCALL_DEFINE0(restart_syscall)
2520 {
2521 	struct restart_block *restart = &current_thread_info()->restart_block;
2522 	return restart->fn(restart);
2523 }
2524 
2525 long do_no_restart_syscall(struct restart_block *param)
2526 {
2527 	return -EINTR;
2528 }
2529 
2530 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2531 {
2532 	if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2533 		sigset_t newblocked;
2534 		/* A set of now blocked but previously unblocked signals. */
2535 		sigandnsets(&newblocked, newset, &current->blocked);
2536 		retarget_shared_pending(tsk, &newblocked);
2537 	}
2538 	tsk->blocked = *newset;
2539 	recalc_sigpending();
2540 }
2541 
2542 /**
2543  * set_current_blocked - change current->blocked mask
2544  * @newset: new mask
2545  *
2546  * It is wrong to change ->blocked directly, this helper should be used
2547  * to ensure the process can't miss a shared signal we are going to block.
2548  */
2549 void set_current_blocked(sigset_t *newset)
2550 {
2551 	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2552 	__set_current_blocked(newset);
2553 }
2554 
2555 void __set_current_blocked(const sigset_t *newset)
2556 {
2557 	struct task_struct *tsk = current;
2558 
2559 	spin_lock_irq(&tsk->sighand->siglock);
2560 	__set_task_blocked(tsk, newset);
2561 	spin_unlock_irq(&tsk->sighand->siglock);
2562 }
2563 
2564 /*
2565  * This is also useful for kernel threads that want to temporarily
2566  * (or permanently) block certain signals.
2567  *
2568  * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2569  * interface happily blocks "unblockable" signals like SIGKILL
2570  * and friends.
2571  */
2572 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2573 {
2574 	struct task_struct *tsk = current;
2575 	sigset_t newset;
2576 
2577 	/* Lockless, only current can change ->blocked, never from irq */
2578 	if (oldset)
2579 		*oldset = tsk->blocked;
2580 
2581 	switch (how) {
2582 	case SIG_BLOCK:
2583 		sigorsets(&newset, &tsk->blocked, set);
2584 		break;
2585 	case SIG_UNBLOCK:
2586 		sigandnsets(&newset, &tsk->blocked, set);
2587 		break;
2588 	case SIG_SETMASK:
2589 		newset = *set;
2590 		break;
2591 	default:
2592 		return -EINVAL;
2593 	}
2594 
2595 	__set_current_blocked(&newset);
2596 	return 0;
2597 }
2598 
2599 /**
2600  *  sys_rt_sigprocmask - change the list of currently blocked signals
2601  *  @how: whether to add, remove, or set signals
2602  *  @nset: stores pending signals
2603  *  @oset: previous value of signal mask if non-null
2604  *  @sigsetsize: size of sigset_t type
2605  */
2606 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2607 		sigset_t __user *, oset, size_t, sigsetsize)
2608 {
2609 	sigset_t old_set, new_set;
2610 	int error;
2611 
2612 	/* XXX: Don't preclude handling different sized sigset_t's.  */
2613 	if (sigsetsize != sizeof(sigset_t))
2614 		return -EINVAL;
2615 
2616 	old_set = current->blocked;
2617 
2618 	if (nset) {
2619 		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2620 			return -EFAULT;
2621 		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2622 
2623 		error = sigprocmask(how, &new_set, NULL);
2624 		if (error)
2625 			return error;
2626 	}
2627 
2628 	if (oset) {
2629 		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2630 			return -EFAULT;
2631 	}
2632 
2633 	return 0;
2634 }
2635 
2636 #ifdef CONFIG_COMPAT
2637 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2638 		compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2639 {
2640 #ifdef __BIG_ENDIAN
2641 	sigset_t old_set = current->blocked;
2642 
2643 	/* XXX: Don't preclude handling different sized sigset_t's.  */
2644 	if (sigsetsize != sizeof(sigset_t))
2645 		return -EINVAL;
2646 
2647 	if (nset) {
2648 		compat_sigset_t new32;
2649 		sigset_t new_set;
2650 		int error;
2651 		if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2652 			return -EFAULT;
2653 
2654 		sigset_from_compat(&new_set, &new32);
2655 		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2656 
2657 		error = sigprocmask(how, &new_set, NULL);
2658 		if (error)
2659 			return error;
2660 	}
2661 	if (oset) {
2662 		compat_sigset_t old32;
2663 		sigset_to_compat(&old32, &old_set);
2664 		if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2665 			return -EFAULT;
2666 	}
2667 	return 0;
2668 #else
2669 	return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2670 				  (sigset_t __user *)oset, sigsetsize);
2671 #endif
2672 }
2673 #endif
2674 
2675 static int do_sigpending(void *set, unsigned long sigsetsize)
2676 {
2677 	if (sigsetsize > sizeof(sigset_t))
2678 		return -EINVAL;
2679 
2680 	spin_lock_irq(&current->sighand->siglock);
2681 	sigorsets(set, &current->pending.signal,
2682 		  &current->signal->shared_pending.signal);
2683 	spin_unlock_irq(&current->sighand->siglock);
2684 
2685 	/* Outside the lock because only this thread touches it.  */
2686 	sigandsets(set, &current->blocked, set);
2687 	return 0;
2688 }
2689 
2690 /**
2691  *  sys_rt_sigpending - examine a pending signal that has been raised
2692  *			while blocked
2693  *  @uset: stores pending signals
2694  *  @sigsetsize: size of sigset_t type or larger
2695  */
2696 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2697 {
2698 	sigset_t set;
2699 	int err = do_sigpending(&set, sigsetsize);
2700 	if (!err && copy_to_user(uset, &set, sigsetsize))
2701 		err = -EFAULT;
2702 	return err;
2703 }
2704 
2705 #ifdef CONFIG_COMPAT
2706 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2707 		compat_size_t, sigsetsize)
2708 {
2709 #ifdef __BIG_ENDIAN
2710 	sigset_t set;
2711 	int err = do_sigpending(&set, sigsetsize);
2712 	if (!err) {
2713 		compat_sigset_t set32;
2714 		sigset_to_compat(&set32, &set);
2715 		/* we can get here only if sigsetsize <= sizeof(set) */
2716 		if (copy_to_user(uset, &set32, sigsetsize))
2717 			err = -EFAULT;
2718 	}
2719 	return err;
2720 #else
2721 	return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2722 #endif
2723 }
2724 #endif
2725 
2726 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2727 
2728 int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2729 {
2730 	int err;
2731 
2732 	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2733 		return -EFAULT;
2734 	if (from->si_code < 0)
2735 		return __copy_to_user(to, from, sizeof(siginfo_t))
2736 			? -EFAULT : 0;
2737 	/*
2738 	 * If you change siginfo_t structure, please be sure
2739 	 * this code is fixed accordingly.
2740 	 * Please remember to update the signalfd_copyinfo() function
2741 	 * inside fs/signalfd.c too, in case siginfo_t changes.
2742 	 * It should never copy any pad contained in the structure
2743 	 * to avoid security leaks, but must copy the generic
2744 	 * 3 ints plus the relevant union member.
2745 	 */
2746 	err = __put_user(from->si_signo, &to->si_signo);
2747 	err |= __put_user(from->si_errno, &to->si_errno);
2748 	err |= __put_user((short)from->si_code, &to->si_code);
2749 	switch (from->si_code & __SI_MASK) {
2750 	case __SI_KILL:
2751 		err |= __put_user(from->si_pid, &to->si_pid);
2752 		err |= __put_user(from->si_uid, &to->si_uid);
2753 		break;
2754 	case __SI_TIMER:
2755 		 err |= __put_user(from->si_tid, &to->si_tid);
2756 		 err |= __put_user(from->si_overrun, &to->si_overrun);
2757 		 err |= __put_user(from->si_ptr, &to->si_ptr);
2758 		break;
2759 	case __SI_POLL:
2760 		err |= __put_user(from->si_band, &to->si_band);
2761 		err |= __put_user(from->si_fd, &to->si_fd);
2762 		break;
2763 	case __SI_FAULT:
2764 		err |= __put_user(from->si_addr, &to->si_addr);
2765 #ifdef __ARCH_SI_TRAPNO
2766 		err |= __put_user(from->si_trapno, &to->si_trapno);
2767 #endif
2768 #ifdef BUS_MCEERR_AO
2769 		/*
2770 		 * Other callers might not initialize the si_lsb field,
2771 		 * so check explicitly for the right codes here.
2772 		 */
2773 		if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2774 			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2775 #endif
2776 		break;
2777 	case __SI_CHLD:
2778 		err |= __put_user(from->si_pid, &to->si_pid);
2779 		err |= __put_user(from->si_uid, &to->si_uid);
2780 		err |= __put_user(from->si_status, &to->si_status);
2781 		err |= __put_user(from->si_utime, &to->si_utime);
2782 		err |= __put_user(from->si_stime, &to->si_stime);
2783 		break;
2784 	case __SI_RT: /* This is not generated by the kernel as of now. */
2785 	case __SI_MESGQ: /* But this is */
2786 		err |= __put_user(from->si_pid, &to->si_pid);
2787 		err |= __put_user(from->si_uid, &to->si_uid);
2788 		err |= __put_user(from->si_ptr, &to->si_ptr);
2789 		break;
2790 #ifdef __ARCH_SIGSYS
2791 	case __SI_SYS:
2792 		err |= __put_user(from->si_call_addr, &to->si_call_addr);
2793 		err |= __put_user(from->si_syscall, &to->si_syscall);
2794 		err |= __put_user(from->si_arch, &to->si_arch);
2795 		break;
2796 #endif
2797 	default: /* this is just in case for now ... */
2798 		err |= __put_user(from->si_pid, &to->si_pid);
2799 		err |= __put_user(from->si_uid, &to->si_uid);
2800 		break;
2801 	}
2802 	return err;
2803 }
2804 
2805 #endif
2806 
2807 /**
2808  *  do_sigtimedwait - wait for queued signals specified in @which
2809  *  @which: queued signals to wait for
2810  *  @info: if non-null, the signal's siginfo is returned here
2811  *  @ts: upper bound on process time suspension
2812  */
2813 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2814 			const struct timespec *ts)
2815 {
2816 	struct task_struct *tsk = current;
2817 	long timeout = MAX_SCHEDULE_TIMEOUT;
2818 	sigset_t mask = *which;
2819 	int sig;
2820 
2821 	if (ts) {
2822 		if (!timespec_valid(ts))
2823 			return -EINVAL;
2824 		timeout = timespec_to_jiffies(ts);
2825 		/*
2826 		 * We can be close to the next tick, add another one
2827 		 * to ensure we will wait at least the time asked for.
2828 		 */
2829 		if (ts->tv_sec || ts->tv_nsec)
2830 			timeout++;
2831 	}
2832 
2833 	/*
2834 	 * Invert the set of allowed signals to get those we want to block.
2835 	 */
2836 	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2837 	signotset(&mask);
2838 
2839 	spin_lock_irq(&tsk->sighand->siglock);
2840 	sig = dequeue_signal(tsk, &mask, info);
2841 	if (!sig && timeout) {
2842 		/*
2843 		 * None ready, temporarily unblock those we're interested
2844 		 * while we are sleeping in so that we'll be awakened when
2845 		 * they arrive. Unblocking is always fine, we can avoid
2846 		 * set_current_blocked().
2847 		 */
2848 		tsk->real_blocked = tsk->blocked;
2849 		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2850 		recalc_sigpending();
2851 		spin_unlock_irq(&tsk->sighand->siglock);
2852 
2853 		timeout = freezable_schedule_timeout_interruptible(timeout);
2854 
2855 		spin_lock_irq(&tsk->sighand->siglock);
2856 		__set_task_blocked(tsk, &tsk->real_blocked);
2857 		siginitset(&tsk->real_blocked, 0);
2858 		sig = dequeue_signal(tsk, &mask, info);
2859 	}
2860 	spin_unlock_irq(&tsk->sighand->siglock);
2861 
2862 	if (sig)
2863 		return sig;
2864 	return timeout ? -EINTR : -EAGAIN;
2865 }
2866 
2867 /**
2868  *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
2869  *			in @uthese
2870  *  @uthese: queued signals to wait for
2871  *  @uinfo: if non-null, the signal's siginfo is returned here
2872  *  @uts: upper bound on process time suspension
2873  *  @sigsetsize: size of sigset_t type
2874  */
2875 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2876 		siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2877 		size_t, sigsetsize)
2878 {
2879 	sigset_t these;
2880 	struct timespec ts;
2881 	siginfo_t info;
2882 	int ret;
2883 
2884 	/* XXX: Don't preclude handling different sized sigset_t's.  */
2885 	if (sigsetsize != sizeof(sigset_t))
2886 		return -EINVAL;
2887 
2888 	if (copy_from_user(&these, uthese, sizeof(these)))
2889 		return -EFAULT;
2890 
2891 	if (uts) {
2892 		if (copy_from_user(&ts, uts, sizeof(ts)))
2893 			return -EFAULT;
2894 	}
2895 
2896 	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2897 
2898 	if (ret > 0 && uinfo) {
2899 		if (copy_siginfo_to_user(uinfo, &info))
2900 			ret = -EFAULT;
2901 	}
2902 
2903 	return ret;
2904 }
2905 
2906 /**
2907  *  sys_kill - send a signal to a process
2908  *  @pid: the PID of the process
2909  *  @sig: signal to be sent
2910  */
2911 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2912 {
2913 	struct siginfo info;
2914 
2915 	info.si_signo = sig;
2916 	info.si_errno = 0;
2917 	info.si_code = SI_USER;
2918 	info.si_pid = task_tgid_vnr(current);
2919 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2920 
2921 	return kill_something_info(sig, &info, pid);
2922 }
2923 
2924 static int
2925 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2926 {
2927 	struct task_struct *p;
2928 	int error = -ESRCH;
2929 
2930 	rcu_read_lock();
2931 	p = find_task_by_vpid(pid);
2932 	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2933 		error = check_kill_permission(sig, info, p);
2934 		/*
2935 		 * The null signal is a permissions and process existence
2936 		 * probe.  No signal is actually delivered.
2937 		 */
2938 		if (!error && sig) {
2939 			error = do_send_sig_info(sig, info, p, false);
2940 			/*
2941 			 * If lock_task_sighand() failed we pretend the task
2942 			 * dies after receiving the signal. The window is tiny,
2943 			 * and the signal is private anyway.
2944 			 */
2945 			if (unlikely(error == -ESRCH))
2946 				error = 0;
2947 		}
2948 	}
2949 	rcu_read_unlock();
2950 
2951 	return error;
2952 }
2953 
2954 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2955 {
2956 	struct siginfo info = {};
2957 
2958 	info.si_signo = sig;
2959 	info.si_errno = 0;
2960 	info.si_code = SI_TKILL;
2961 	info.si_pid = task_tgid_vnr(current);
2962 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2963 
2964 	return do_send_specific(tgid, pid, sig, &info);
2965 }
2966 
2967 /**
2968  *  sys_tgkill - send signal to one specific thread
2969  *  @tgid: the thread group ID of the thread
2970  *  @pid: the PID of the thread
2971  *  @sig: signal to be sent
2972  *
2973  *  This syscall also checks the @tgid and returns -ESRCH even if the PID
2974  *  exists but it's not belonging to the target process anymore. This
2975  *  method solves the problem of threads exiting and PIDs getting reused.
2976  */
2977 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2978 {
2979 	/* This is only valid for single tasks */
2980 	if (pid <= 0 || tgid <= 0)
2981 		return -EINVAL;
2982 
2983 	return do_tkill(tgid, pid, sig);
2984 }
2985 
2986 /**
2987  *  sys_tkill - send signal to one specific task
2988  *  @pid: the PID of the task
2989  *  @sig: signal to be sent
2990  *
2991  *  Send a signal to only one task, even if it's a CLONE_THREAD task.
2992  */
2993 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2994 {
2995 	/* This is only valid for single tasks */
2996 	if (pid <= 0)
2997 		return -EINVAL;
2998 
2999 	return do_tkill(0, pid, sig);
3000 }
3001 
3002 static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3003 {
3004 	/* Not even root can pretend to send signals from the kernel.
3005 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3006 	 */
3007 	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3008 	    (task_pid_vnr(current) != pid)) {
3009 		/* We used to allow any < 0 si_code */
3010 		WARN_ON_ONCE(info->si_code < 0);
3011 		return -EPERM;
3012 	}
3013 	info->si_signo = sig;
3014 
3015 	/* POSIX.1b doesn't mention process groups.  */
3016 	return kill_proc_info(sig, info, pid);
3017 }
3018 
3019 /**
3020  *  sys_rt_sigqueueinfo - send signal information to a signal
3021  *  @pid: the PID of the thread
3022  *  @sig: signal to be sent
3023  *  @uinfo: signal info to be sent
3024  */
3025 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3026 		siginfo_t __user *, uinfo)
3027 {
3028 	siginfo_t info;
3029 	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3030 		return -EFAULT;
3031 	return do_rt_sigqueueinfo(pid, sig, &info);
3032 }
3033 
3034 #ifdef CONFIG_COMPAT
3035 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3036 			compat_pid_t, pid,
3037 			int, sig,
3038 			struct compat_siginfo __user *, uinfo)
3039 {
3040 	siginfo_t info;
3041 	int ret = copy_siginfo_from_user32(&info, uinfo);
3042 	if (unlikely(ret))
3043 		return ret;
3044 	return do_rt_sigqueueinfo(pid, sig, &info);
3045 }
3046 #endif
3047 
3048 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3049 {
3050 	/* This is only valid for single tasks */
3051 	if (pid <= 0 || tgid <= 0)
3052 		return -EINVAL;
3053 
3054 	/* Not even root can pretend to send signals from the kernel.
3055 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3056 	 */
3057 	if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
3058 	    (task_pid_vnr(current) != pid)) {
3059 		/* We used to allow any < 0 si_code */
3060 		WARN_ON_ONCE(info->si_code < 0);
3061 		return -EPERM;
3062 	}
3063 	info->si_signo = sig;
3064 
3065 	return do_send_specific(tgid, pid, sig, info);
3066 }
3067 
3068 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3069 		siginfo_t __user *, uinfo)
3070 {
3071 	siginfo_t info;
3072 
3073 	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3074 		return -EFAULT;
3075 
3076 	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3077 }
3078 
3079 #ifdef CONFIG_COMPAT
3080 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3081 			compat_pid_t, tgid,
3082 			compat_pid_t, pid,
3083 			int, sig,
3084 			struct compat_siginfo __user *, uinfo)
3085 {
3086 	siginfo_t info;
3087 
3088 	if (copy_siginfo_from_user32(&info, uinfo))
3089 		return -EFAULT;
3090 	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3091 }
3092 #endif
3093 
3094 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3095 {
3096 	struct task_struct *t = current;
3097 	struct k_sigaction *k;
3098 	sigset_t mask;
3099 
3100 	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3101 		return -EINVAL;
3102 
3103 	k = &t->sighand->action[sig-1];
3104 
3105 	spin_lock_irq(&current->sighand->siglock);
3106 	if (oact)
3107 		*oact = *k;
3108 
3109 	if (act) {
3110 		sigdelsetmask(&act->sa.sa_mask,
3111 			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3112 		*k = *act;
3113 		/*
3114 		 * POSIX 3.3.1.3:
3115 		 *  "Setting a signal action to SIG_IGN for a signal that is
3116 		 *   pending shall cause the pending signal to be discarded,
3117 		 *   whether or not it is blocked."
3118 		 *
3119 		 *  "Setting a signal action to SIG_DFL for a signal that is
3120 		 *   pending and whose default action is to ignore the signal
3121 		 *   (for example, SIGCHLD), shall cause the pending signal to
3122 		 *   be discarded, whether or not it is blocked"
3123 		 */
3124 		if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3125 			sigemptyset(&mask);
3126 			sigaddset(&mask, sig);
3127 			rm_from_queue_full(&mask, &t->signal->shared_pending);
3128 			do {
3129 				rm_from_queue_full(&mask, &t->pending);
3130 			} while_each_thread(current, t);
3131 		}
3132 	}
3133 
3134 	spin_unlock_irq(&current->sighand->siglock);
3135 	return 0;
3136 }
3137 
3138 static int
3139 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3140 {
3141 	stack_t oss;
3142 	int error;
3143 
3144 	oss.ss_sp = (void __user *) current->sas_ss_sp;
3145 	oss.ss_size = current->sas_ss_size;
3146 	oss.ss_flags = sas_ss_flags(sp);
3147 
3148 	if (uss) {
3149 		void __user *ss_sp;
3150 		size_t ss_size;
3151 		int ss_flags;
3152 
3153 		error = -EFAULT;
3154 		if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3155 			goto out;
3156 		error = __get_user(ss_sp, &uss->ss_sp) |
3157 			__get_user(ss_flags, &uss->ss_flags) |
3158 			__get_user(ss_size, &uss->ss_size);
3159 		if (error)
3160 			goto out;
3161 
3162 		error = -EPERM;
3163 		if (on_sig_stack(sp))
3164 			goto out;
3165 
3166 		error = -EINVAL;
3167 		/*
3168 		 * Note - this code used to test ss_flags incorrectly:
3169 		 *  	  old code may have been written using ss_flags==0
3170 		 *	  to mean ss_flags==SS_ONSTACK (as this was the only
3171 		 *	  way that worked) - this fix preserves that older
3172 		 *	  mechanism.
3173 		 */
3174 		if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3175 			goto out;
3176 
3177 		if (ss_flags == SS_DISABLE) {
3178 			ss_size = 0;
3179 			ss_sp = NULL;
3180 		} else {
3181 			error = -ENOMEM;
3182 			if (ss_size < MINSIGSTKSZ)
3183 				goto out;
3184 		}
3185 
3186 		current->sas_ss_sp = (unsigned long) ss_sp;
3187 		current->sas_ss_size = ss_size;
3188 	}
3189 
3190 	error = 0;
3191 	if (uoss) {
3192 		error = -EFAULT;
3193 		if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3194 			goto out;
3195 		error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3196 			__put_user(oss.ss_size, &uoss->ss_size) |
3197 			__put_user(oss.ss_flags, &uoss->ss_flags);
3198 	}
3199 
3200 out:
3201 	return error;
3202 }
3203 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3204 {
3205 	return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3206 }
3207 
3208 int restore_altstack(const stack_t __user *uss)
3209 {
3210 	int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3211 	/* squash all but EFAULT for now */
3212 	return err == -EFAULT ? err : 0;
3213 }
3214 
3215 int __save_altstack(stack_t __user *uss, unsigned long sp)
3216 {
3217 	struct task_struct *t = current;
3218 	return  __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3219 		__put_user(sas_ss_flags(sp), &uss->ss_flags) |
3220 		__put_user(t->sas_ss_size, &uss->ss_size);
3221 }
3222 
3223 #ifdef CONFIG_COMPAT
3224 COMPAT_SYSCALL_DEFINE2(sigaltstack,
3225 			const compat_stack_t __user *, uss_ptr,
3226 			compat_stack_t __user *, uoss_ptr)
3227 {
3228 	stack_t uss, uoss;
3229 	int ret;
3230 	mm_segment_t seg;
3231 
3232 	if (uss_ptr) {
3233 		compat_stack_t uss32;
3234 
3235 		memset(&uss, 0, sizeof(stack_t));
3236 		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3237 			return -EFAULT;
3238 		uss.ss_sp = compat_ptr(uss32.ss_sp);
3239 		uss.ss_flags = uss32.ss_flags;
3240 		uss.ss_size = uss32.ss_size;
3241 	}
3242 	seg = get_fs();
3243 	set_fs(KERNEL_DS);
3244 	ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3245 			     (stack_t __force __user *) &uoss,
3246 			     compat_user_stack_pointer());
3247 	set_fs(seg);
3248 	if (ret >= 0 && uoss_ptr)  {
3249 		if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3250 		    __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3251 		    __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3252 		    __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3253 			ret = -EFAULT;
3254 	}
3255 	return ret;
3256 }
3257 
3258 int compat_restore_altstack(const compat_stack_t __user *uss)
3259 {
3260 	int err = compat_sys_sigaltstack(uss, NULL);
3261 	/* squash all but -EFAULT for now */
3262 	return err == -EFAULT ? err : 0;
3263 }
3264 
3265 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3266 {
3267 	struct task_struct *t = current;
3268 	return  __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3269 		__put_user(sas_ss_flags(sp), &uss->ss_flags) |
3270 		__put_user(t->sas_ss_size, &uss->ss_size);
3271 }
3272 #endif
3273 
3274 #ifdef __ARCH_WANT_SYS_SIGPENDING
3275 
3276 /**
3277  *  sys_sigpending - examine pending signals
3278  *  @set: where mask of pending signal is returned
3279  */
3280 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3281 {
3282 	return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3283 }
3284 
3285 #endif
3286 
3287 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3288 /**
3289  *  sys_sigprocmask - examine and change blocked signals
3290  *  @how: whether to add, remove, or set signals
3291  *  @nset: signals to add or remove (if non-null)
3292  *  @oset: previous value of signal mask if non-null
3293  *
3294  * Some platforms have their own version with special arguments;
3295  * others support only sys_rt_sigprocmask.
3296  */
3297 
3298 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3299 		old_sigset_t __user *, oset)
3300 {
3301 	old_sigset_t old_set, new_set;
3302 	sigset_t new_blocked;
3303 
3304 	old_set = current->blocked.sig[0];
3305 
3306 	if (nset) {
3307 		if (copy_from_user(&new_set, nset, sizeof(*nset)))
3308 			return -EFAULT;
3309 
3310 		new_blocked = current->blocked;
3311 
3312 		switch (how) {
3313 		case SIG_BLOCK:
3314 			sigaddsetmask(&new_blocked, new_set);
3315 			break;
3316 		case SIG_UNBLOCK:
3317 			sigdelsetmask(&new_blocked, new_set);
3318 			break;
3319 		case SIG_SETMASK:
3320 			new_blocked.sig[0] = new_set;
3321 			break;
3322 		default:
3323 			return -EINVAL;
3324 		}
3325 
3326 		set_current_blocked(&new_blocked);
3327 	}
3328 
3329 	if (oset) {
3330 		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3331 			return -EFAULT;
3332 	}
3333 
3334 	return 0;
3335 }
3336 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3337 
3338 #ifndef CONFIG_ODD_RT_SIGACTION
3339 /**
3340  *  sys_rt_sigaction - alter an action taken by a process
3341  *  @sig: signal to be sent
3342  *  @act: new sigaction
3343  *  @oact: used to save the previous sigaction
3344  *  @sigsetsize: size of sigset_t type
3345  */
3346 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3347 		const struct sigaction __user *, act,
3348 		struct sigaction __user *, oact,
3349 		size_t, sigsetsize)
3350 {
3351 	struct k_sigaction new_sa, old_sa;
3352 	int ret = -EINVAL;
3353 
3354 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3355 	if (sigsetsize != sizeof(sigset_t))
3356 		goto out;
3357 
3358 	if (act) {
3359 		if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3360 			return -EFAULT;
3361 	}
3362 
3363 	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3364 
3365 	if (!ret && oact) {
3366 		if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3367 			return -EFAULT;
3368 	}
3369 out:
3370 	return ret;
3371 }
3372 #ifdef CONFIG_COMPAT
3373 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3374 		const struct compat_sigaction __user *, act,
3375 		struct compat_sigaction __user *, oact,
3376 		compat_size_t, sigsetsize)
3377 {
3378 	struct k_sigaction new_ka, old_ka;
3379 	compat_sigset_t mask;
3380 #ifdef __ARCH_HAS_SA_RESTORER
3381 	compat_uptr_t restorer;
3382 #endif
3383 	int ret;
3384 
3385 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3386 	if (sigsetsize != sizeof(compat_sigset_t))
3387 		return -EINVAL;
3388 
3389 	if (act) {
3390 		compat_uptr_t handler;
3391 		ret = get_user(handler, &act->sa_handler);
3392 		new_ka.sa.sa_handler = compat_ptr(handler);
3393 #ifdef __ARCH_HAS_SA_RESTORER
3394 		ret |= get_user(restorer, &act->sa_restorer);
3395 		new_ka.sa.sa_restorer = compat_ptr(restorer);
3396 #endif
3397 		ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3398 		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3399 		if (ret)
3400 			return -EFAULT;
3401 		sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3402 	}
3403 
3404 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3405 	if (!ret && oact) {
3406 		sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3407 		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3408 			       &oact->sa_handler);
3409 		ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3410 		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3411 #ifdef __ARCH_HAS_SA_RESTORER
3412 		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3413 				&oact->sa_restorer);
3414 #endif
3415 	}
3416 	return ret;
3417 }
3418 #endif
3419 #endif /* !CONFIG_ODD_RT_SIGACTION */
3420 
3421 #ifdef CONFIG_OLD_SIGACTION
3422 SYSCALL_DEFINE3(sigaction, int, sig,
3423 		const struct old_sigaction __user *, act,
3424 	        struct old_sigaction __user *, oact)
3425 {
3426 	struct k_sigaction new_ka, old_ka;
3427 	int ret;
3428 
3429 	if (act) {
3430 		old_sigset_t mask;
3431 		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3432 		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3433 		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3434 		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3435 		    __get_user(mask, &act->sa_mask))
3436 			return -EFAULT;
3437 #ifdef __ARCH_HAS_KA_RESTORER
3438 		new_ka.ka_restorer = NULL;
3439 #endif
3440 		siginitset(&new_ka.sa.sa_mask, mask);
3441 	}
3442 
3443 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3444 
3445 	if (!ret && oact) {
3446 		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3447 		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3448 		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3449 		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3450 		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3451 			return -EFAULT;
3452 	}
3453 
3454 	return ret;
3455 }
3456 #endif
3457 #ifdef CONFIG_COMPAT_OLD_SIGACTION
3458 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3459 		const struct compat_old_sigaction __user *, act,
3460 	        struct compat_old_sigaction __user *, oact)
3461 {
3462 	struct k_sigaction new_ka, old_ka;
3463 	int ret;
3464 	compat_old_sigset_t mask;
3465 	compat_uptr_t handler, restorer;
3466 
3467 	if (act) {
3468 		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3469 		    __get_user(handler, &act->sa_handler) ||
3470 		    __get_user(restorer, &act->sa_restorer) ||
3471 		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3472 		    __get_user(mask, &act->sa_mask))
3473 			return -EFAULT;
3474 
3475 #ifdef __ARCH_HAS_KA_RESTORER
3476 		new_ka.ka_restorer = NULL;
3477 #endif
3478 		new_ka.sa.sa_handler = compat_ptr(handler);
3479 		new_ka.sa.sa_restorer = compat_ptr(restorer);
3480 		siginitset(&new_ka.sa.sa_mask, mask);
3481 	}
3482 
3483 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3484 
3485 	if (!ret && oact) {
3486 		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3487 		    __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3488 			       &oact->sa_handler) ||
3489 		    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3490 			       &oact->sa_restorer) ||
3491 		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3492 		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3493 			return -EFAULT;
3494 	}
3495 	return ret;
3496 }
3497 #endif
3498 
3499 #ifdef __ARCH_WANT_SYS_SGETMASK
3500 
3501 /*
3502  * For backwards compatibility.  Functionality superseded by sigprocmask.
3503  */
3504 SYSCALL_DEFINE0(sgetmask)
3505 {
3506 	/* SMP safe */
3507 	return current->blocked.sig[0];
3508 }
3509 
3510 SYSCALL_DEFINE1(ssetmask, int, newmask)
3511 {
3512 	int old = current->blocked.sig[0];
3513 	sigset_t newset;
3514 
3515 	siginitset(&newset, newmask);
3516 	set_current_blocked(&newset);
3517 
3518 	return old;
3519 }
3520 #endif /* __ARCH_WANT_SGETMASK */
3521 
3522 #ifdef __ARCH_WANT_SYS_SIGNAL
3523 /*
3524  * For backwards compatibility.  Functionality superseded by sigaction.
3525  */
3526 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3527 {
3528 	struct k_sigaction new_sa, old_sa;
3529 	int ret;
3530 
3531 	new_sa.sa.sa_handler = handler;
3532 	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3533 	sigemptyset(&new_sa.sa.sa_mask);
3534 
3535 	ret = do_sigaction(sig, &new_sa, &old_sa);
3536 
3537 	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3538 }
3539 #endif /* __ARCH_WANT_SYS_SIGNAL */
3540 
3541 #ifdef __ARCH_WANT_SYS_PAUSE
3542 
3543 SYSCALL_DEFINE0(pause)
3544 {
3545 	while (!signal_pending(current)) {
3546 		current->state = TASK_INTERRUPTIBLE;
3547 		schedule();
3548 	}
3549 	return -ERESTARTNOHAND;
3550 }
3551 
3552 #endif
3553 
3554 int sigsuspend(sigset_t *set)
3555 {
3556 	current->saved_sigmask = current->blocked;
3557 	set_current_blocked(set);
3558 
3559 	current->state = TASK_INTERRUPTIBLE;
3560 	schedule();
3561 	set_restore_sigmask();
3562 	return -ERESTARTNOHAND;
3563 }
3564 
3565 /**
3566  *  sys_rt_sigsuspend - replace the signal mask for a value with the
3567  *	@unewset value until a signal is received
3568  *  @unewset: new signal mask value
3569  *  @sigsetsize: size of sigset_t type
3570  */
3571 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3572 {
3573 	sigset_t newset;
3574 
3575 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3576 	if (sigsetsize != sizeof(sigset_t))
3577 		return -EINVAL;
3578 
3579 	if (copy_from_user(&newset, unewset, sizeof(newset)))
3580 		return -EFAULT;
3581 	return sigsuspend(&newset);
3582 }
3583 
3584 #ifdef CONFIG_COMPAT
3585 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3586 {
3587 #ifdef __BIG_ENDIAN
3588 	sigset_t newset;
3589 	compat_sigset_t newset32;
3590 
3591 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3592 	if (sigsetsize != sizeof(sigset_t))
3593 		return -EINVAL;
3594 
3595 	if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3596 		return -EFAULT;
3597 	sigset_from_compat(&newset, &newset32);
3598 	return sigsuspend(&newset);
3599 #else
3600 	/* on little-endian bitmaps don't care about granularity */
3601 	return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3602 #endif
3603 }
3604 #endif
3605 
3606 #ifdef CONFIG_OLD_SIGSUSPEND
3607 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3608 {
3609 	sigset_t blocked;
3610 	siginitset(&blocked, mask);
3611 	return sigsuspend(&blocked);
3612 }
3613 #endif
3614 #ifdef CONFIG_OLD_SIGSUSPEND3
3615 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3616 {
3617 	sigset_t blocked;
3618 	siginitset(&blocked, mask);
3619 	return sigsuspend(&blocked);
3620 }
3621 #endif
3622 
3623 __weak const char *arch_vma_name(struct vm_area_struct *vma)
3624 {
3625 	return NULL;
3626 }
3627 
3628 void __init signals_init(void)
3629 {
3630 	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3631 }
3632 
3633 #ifdef CONFIG_KGDB_KDB
3634 #include <linux/kdb.h>
3635 /*
3636  * kdb_send_sig_info - Allows kdb to send signals without exposing
3637  * signal internals.  This function checks if the required locks are
3638  * available before calling the main signal code, to avoid kdb
3639  * deadlocks.
3640  */
3641 void
3642 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3643 {
3644 	static struct task_struct *kdb_prev_t;
3645 	int sig, new_t;
3646 	if (!spin_trylock(&t->sighand->siglock)) {
3647 		kdb_printf("Can't do kill command now.\n"
3648 			   "The sigmask lock is held somewhere else in "
3649 			   "kernel, try again later\n");
3650 		return;
3651 	}
3652 	spin_unlock(&t->sighand->siglock);
3653 	new_t = kdb_prev_t != t;
3654 	kdb_prev_t = t;
3655 	if (t->state != TASK_RUNNING && new_t) {
3656 		kdb_printf("Process is not RUNNING, sending a signal from "
3657 			   "kdb risks deadlock\n"
3658 			   "on the run queue locks. "
3659 			   "The signal has _not_ been sent.\n"
3660 			   "Reissue the kill command if you want to risk "
3661 			   "the deadlock.\n");
3662 		return;
3663 	}
3664 	sig = info->si_signo;
3665 	if (send_sig_info(sig, info, t))
3666 		kdb_printf("Fail to deliver Signal %d to process %d.\n",
3667 			   sig, t->pid);
3668 	else
3669 		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3670 }
3671 #endif	/* CONFIG_KGDB_KDB */
3672