path: root/kernel/signal.c (plain)
blob: c091dcc9f19b0d84f664040ab3363d085594778f

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 && sig_kernel_only(sig)))
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	/*
92	* Tracers may want to know about even ignored signal unless it
93	* is SIGKILL which can't be reported anyway but can be ignored
94	* by SIGNAL_UNKILLABLE task.
95	*/
96	if (t->ptrace && sig != SIGKILL)
97	return 0;
98
99	return sig_task_ignored(t, sig, force);
100	}
101
102	/*
103	* Re-calculate pending state from the set of locally pending
104	* signals, globally pending signals, and blocked signals.
105	*/
106	static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
107	{
108	unsigned long ready;
109	long i;
110
111	switch (_NSIG_WORDS) {
112	default:
113	for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
114	ready |= signal->sig[i] &~ blocked->sig[i];
115	break;
116
117	case 4: ready = signal->sig[3] &~ blocked->sig[3];
118	ready |= signal->sig[2] &~ blocked->sig[2];
119	ready |= signal->sig[1] &~ blocked->sig[1];
120	ready |= signal->sig[0] &~ blocked->sig[0];
121	break;
122
123	case 2: ready = signal->sig[1] &~ blocked->sig[1];
124	ready |= signal->sig[0] &~ blocked->sig[0];
125	break;
126
127	case 1: ready = signal->sig[0] &~ blocked->sig[0];
128	}
129	return ready != 0;
130	}
131
132	#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
133
134	static int recalc_sigpending_tsk(struct task_struct *t)
135	{
136	if ((t->jobctl & JOBCTL_PENDING_MASK) ||
137	PENDING(&t->pending, &t->blocked) ||
138	PENDING(&t->signal->shared_pending, &t->blocked)) {
139	set_tsk_thread_flag(t, TIF_SIGPENDING);
140	return 1;
141	}
142	/*
143	* We must never clear the flag in another thread, or in current
144	* when it's possible the current syscall is returning -ERESTART*.
145	* So we don't clear it here, and only callers who know they should do.
146	*/
147	return 0;
148	}
149
150	/*
151	* After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
152	* This is superfluous when called on current, the wakeup is a harmless no-op.
153	*/
154	void recalc_sigpending_and_wake(struct task_struct *t)
155	{
156	if (recalc_sigpending_tsk(t))
157	signal_wake_up(t, 0);
158	}
159
160	void recalc_sigpending(void)
161	{
162	if (!recalc_sigpending_tsk(current) && !freezing(current))
163	clear_thread_flag(TIF_SIGPENDING);
164
165	}
166
167	/* Given the mask, find the first available signal that should be serviced. */
168
169	#define SYNCHRONOUS_MASK \
170	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
171	sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
172
173	int next_signal(struct sigpending *pending, sigset_t *mask)
174	{
175	unsigned long i, *s, *m, x;
176	int sig = 0;
177
178	s = pending->signal.sig;
179	m = mask->sig;
180
181	/*
182	* Handle the first word specially: it contains the
183	* synchronous signals that need to be dequeued first.
184	*/
185	x = *s &~ *m;
186	if (x) {
187	if (x & SYNCHRONOUS_MASK)
188	x &= SYNCHRONOUS_MASK;
189	sig = ffz(~x) + 1;
190	return sig;
191	}
192
193	switch (_NSIG_WORDS) {
194	default:
195	for (i = 1; i < _NSIG_WORDS; ++i) {
196	x = *++s &~ *++m;
197	if (!x)
198	continue;
199	sig = ffz(~x) + i*_NSIG_BPW + 1;
200	break;
201	}
202	break;
203
204	case 2:
205	x = s[1] &~ m[1];
206	if (!x)
207	break;
208	sig = ffz(~x) + _NSIG_BPW + 1;
209	break;
210
211	case 1:
212	/* Nothing to do */
213	break;
214	}
215
216	return sig;
217	}
218
219	static inline void print_dropped_signal(int sig)
220	{
221	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
222
223	if (!print_fatal_signals)
224	return;
225
226	if (!__ratelimit(&ratelimit_state))
227	return;
228
229	pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
230	current->comm, current->pid, sig);
231	}
232
233	/**
234	* task_set_jobctl_pending - set jobctl pending bits
235	* @task: target task
236	* @mask: pending bits to set
237	*
238	* Clear @mask from @task->jobctl. @mask must be subset of
239	* %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
240	* %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
241	* cleared. If @task is already being killed or exiting, this function
242	* becomes noop.
243	*
244	* CONTEXT:
245	* Must be called with @task->sighand->siglock held.
246	*
247	* RETURNS:
248	* %true if @mask is set, %false if made noop because @task was dying.
249	*/
250	bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
251	{
252	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
253	JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
254	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
255
256	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
257	return false;
258
259	if (mask & JOBCTL_STOP_SIGMASK)
260	task->jobctl &= ~JOBCTL_STOP_SIGMASK;
261
262	task->jobctl |= mask;
263	return true;
264	}
265
266	/**
267	* task_clear_jobctl_trapping - clear jobctl trapping bit
268	* @task: target task
269	*
270	* If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
271	* Clear it and wake up the ptracer. Note that we don't need any further
272	* locking. @task->siglock guarantees that @task->parent points to the
273	* ptracer.
274	*
275	* CONTEXT:
276	* Must be called with @task->sighand->siglock held.
277	*/
278	void task_clear_jobctl_trapping(struct task_struct *task)
279	{
280	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
281	task->jobctl &= ~JOBCTL_TRAPPING;
282	smp_mb(); /* advised by wake_up_bit() */
283	wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
284	}
285	}
286
287	/**
288	* task_clear_jobctl_pending - clear jobctl pending bits
289	* @task: target task
290	* @mask: pending bits to clear
291	*
292	* Clear @mask from @task->jobctl. @mask must be subset of
293	* %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
294	* STOP bits are cleared together.
295	*
296	* If clearing of @mask leaves no stop or trap pending, this function calls
297	* task_clear_jobctl_trapping().
298	*
299	* CONTEXT:
300	* Must be called with @task->sighand->siglock held.
301	*/
302	void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
303	{
304	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
305
306	if (mask & JOBCTL_STOP_PENDING)
307	mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
308
309	task->jobctl &= ~mask;
310
311	if (!(task->jobctl & JOBCTL_PENDING_MASK))
312	task_clear_jobctl_trapping(task);
313	}
314
315	/**
316	* task_participate_group_stop - participate in a group stop
317	* @task: task participating in a group stop
318	*
319	* @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
320	* Group stop states are cleared and the group stop count is consumed if
321	* %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
322	* stop, the appropriate %SIGNAL_* flags are set.
323	*
324	* CONTEXT:
325	* Must be called with @task->sighand->siglock held.
326	*
327	* RETURNS:
328	* %true if group stop completion should be notified to the parent, %false
329	* otherwise.
330	*/
331	static bool task_participate_group_stop(struct task_struct *task)
332	{
333	struct signal_struct *sig = task->signal;
334	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
335
336	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
337
338	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
339
340	if (!consume)
341	return false;
342
343	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
344	sig->group_stop_count--;
345
346	/*
347	* Tell the caller to notify completion iff we are entering into a
348	* fresh group stop. Read comment in do_signal_stop() for details.
349	*/
350	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
351	signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
352	return true;
353	}
354	return false;
355	}
356
357	/*
358	* allocate a new signal queue record
359	* - this may be called without locks if and only if t == current, otherwise an
360	* appropriate lock must be held to stop the target task from exiting
361	*/
362	static struct sigqueue *
363	__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
364	{
365	struct sigqueue *q = NULL;
366	struct user_struct *user;
367
368	/*
369	* Protect access to @t credentials. This can go away when all
370	* callers hold rcu read lock.
371	*/
372	rcu_read_lock();
373	user = get_uid(__task_cred(t)->user);
374	atomic_inc(&user->sigpending);
375	rcu_read_unlock();
376
377	if (override_rlimit ||
378	atomic_read(&user->sigpending) <=
379	task_rlimit(t, RLIMIT_SIGPENDING)) {
380	q = kmem_cache_alloc(sigqueue_cachep, flags);
381	} else {
382	print_dropped_signal(sig);
383	}
384
385	if (unlikely(q == NULL)) {
386	atomic_dec(&user->sigpending);
387	free_uid(user);
388	} else {
389	INIT_LIST_HEAD(&q->list);
390	q->flags = 0;
391	q->user = user;
392	}
393
394	return q;
395	}
396
397	static void __sigqueue_free(struct sigqueue *q)
398	{
399	if (q->flags & SIGQUEUE_PREALLOC)
400	return;
401	atomic_dec(&q->user->sigpending);
402	free_uid(q->user);
403	kmem_cache_free(sigqueue_cachep, q);
404	}
405
406	void flush_sigqueue(struct sigpending *queue)
407	{
408	struct sigqueue *q;
409
410	sigemptyset(&queue->signal);
411	while (!list_empty(&queue->list)) {
412	q = list_entry(queue->list.next, struct sigqueue , list);
413	list_del_init(&q->list);
414	__sigqueue_free(q);
415	}
416	}
417
418	/*
419	* Flush all pending signals for this kthread.
420	*/
421	void flush_signals(struct task_struct *t)
422	{
423	unsigned long flags;
424
425	spin_lock_irqsave(&t->sighand->siglock, flags);
426	clear_tsk_thread_flag(t, TIF_SIGPENDING);
427	flush_sigqueue(&t->pending);
428	flush_sigqueue(&t->signal->shared_pending);
429	spin_unlock_irqrestore(&t->sighand->siglock, flags);
430	}
431
432	static void __flush_itimer_signals(struct sigpending *pending)
433	{
434	sigset_t signal, retain;
435	struct sigqueue *q, *n;
436
437	signal = pending->signal;
438	sigemptyset(&retain);
439
440	list_for_each_entry_safe(q, n, &pending->list, list) {
441	int sig = q->info.si_signo;
442
443	if (likely(q->info.si_code != SI_TIMER)) {
444	sigaddset(&retain, sig);
445	} else {
446	sigdelset(&signal, sig);
447	list_del_init(&q->list);
448	__sigqueue_free(q);
449	}
450	}
451
452	sigorsets(&pending->signal, &signal, &retain);
453	}
454
455	void flush_itimer_signals(void)
456	{
457	struct task_struct *tsk = current;
458	unsigned long flags;
459
460	spin_lock_irqsave(&tsk->sighand->siglock, flags);
461	__flush_itimer_signals(&tsk->pending);
462	__flush_itimer_signals(&tsk->signal->shared_pending);
463	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
464	}
465
466	void ignore_signals(struct task_struct *t)
467	{
468	int i;
469
470	for (i = 0; i < _NSIG; ++i)
471	t->sighand->action[i].sa.sa_handler = SIG_IGN;
472
473	flush_signals(t);
474	}
475
476	/*
477	* Flush all handlers for a task.
478	*/
479
480	void
481	flush_signal_handlers(struct task_struct *t, int force_default)
482	{
483	int i;
484	struct k_sigaction *ka = &t->sighand->action[0];
485	for (i = _NSIG ; i != 0 ; i--) {
486	if (force_default || ka->sa.sa_handler != SIG_IGN)
487	ka->sa.sa_handler = SIG_DFL;
488	ka->sa.sa_flags = 0;
489	#ifdef __ARCH_HAS_SA_RESTORER
490	ka->sa.sa_restorer = NULL;
491	#endif
492	sigemptyset(&ka->sa.sa_mask);
493	ka++;
494	}
495	}
496
497	int unhandled_signal(struct task_struct *tsk, int sig)
498	{
499	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
500	if (is_global_init(tsk))
501	return 1;
502	if (handler != SIG_IGN && handler != SIG_DFL)
503	return 0;
504	/* if ptraced, let the tracer determine */
505	return !tsk->ptrace;
506	}
507
508	static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
509	bool *resched_timer)
510	{
511	struct sigqueue *q, *first = NULL;
512
513	/*
514	* Collect the siginfo appropriate to this signal. Check if
515	* there is another siginfo for the same signal.
516	*/
517	list_for_each_entry(q, &list->list, list) {
518	if (q->info.si_signo == sig) {
519	if (first)
520	goto still_pending;
521	first = q;
522	}
523	}
524
525	sigdelset(&list->signal, sig);
526
527	if (first) {
528	still_pending:
529	list_del_init(&first->list);
530	copy_siginfo(info, &first->info);
531
532	*resched_timer =
533	(first->flags & SIGQUEUE_PREALLOC) &&
534	(info->si_code == SI_TIMER) &&
535	(info->si_sys_private);
536
537	__sigqueue_free(first);
538	} else {
539	/*
540	* Ok, it wasn't in the queue. This must be
541	* a fast-pathed signal or we must have been
542	* out of queue space. So zero out the info.
543	*/
544	info->si_signo = sig;
545	info->si_errno = 0;
546	info->si_code = SI_USER;
547	info->si_pid = 0;
548	info->si_uid = 0;
549	}
550	}
551
552	static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
553	siginfo_t *info, bool *resched_timer)
554	{
555	int sig = next_signal(pending, mask);
556
557	if (sig)
558	collect_signal(sig, pending, info, resched_timer);
559	return sig;
560	}
561
562	/*
563	* Dequeue a signal and return the element to the caller, which is
564	* expected to free it.
565	*
566	* All callers have to hold the siglock.
567	*/
568	int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
569	{
570	bool resched_timer = false;
571	int signr;
572
573	/* We only dequeue private signals from ourselves, we don't let
574	* signalfd steal them
575	*/
576	signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
577	if (!signr) {
578	signr = __dequeue_signal(&tsk->signal->shared_pending,
579	mask, info, &resched_timer);
580	/*
581	* itimer signal ?
582	*
583	* itimers are process shared and we restart periodic
584	* itimers in the signal delivery path to prevent DoS
585	* attacks in the high resolution timer case. This is
586	* compliant with the old way of self-restarting
587	* itimers, as the SIGALRM is a legacy signal and only
588	* queued once. Changing the restart behaviour to
589	* restart the timer in the signal dequeue path is
590	* reducing the timer noise on heavy loaded !highres
591	* systems too.
592	*/
593	if (unlikely(signr == SIGALRM)) {
594	struct hrtimer *tmr = &tsk->signal->real_timer;
595
596	if (!hrtimer_is_queued(tmr) &&
597	tsk->signal->it_real_incr.tv64 != 0) {
598	hrtimer_forward(tmr, tmr->base->get_time(),
599	tsk->signal->it_real_incr);
600	hrtimer_restart(tmr);
601	}
602	}
603	}
604
605	recalc_sigpending();
606	if (!signr)
607	return 0;
608
609	if (unlikely(sig_kernel_stop(signr))) {
610	/*
611	* Set a marker that we have dequeued a stop signal. Our
612	* caller might release the siglock and then the pending
613	* stop signal it is about to process is no longer in the
614	* pending bitmasks, but must still be cleared by a SIGCONT
615	* (and overruled by a SIGKILL). So those cases clear this
616	* shared flag after we've set it. Note that this flag may
617	* remain set after the signal we return is ignored or
618	* handled. That doesn't matter because its only purpose
619	* is to alert stop-signal processing code when another
620	* processor has come along and cleared the flag.
621	*/
622	current->jobctl |= JOBCTL_STOP_DEQUEUED;
623	}
624	if (resched_timer) {
625	/*
626	* Release the siglock to ensure proper locking order
627	* of timer locks outside of siglocks. Note, we leave
628	* irqs disabled here, since the posix-timers code is
629	* about to disable them again anyway.
630	*/
631	spin_unlock(&tsk->sighand->siglock);
632	do_schedule_next_timer(info);
633	spin_lock(&tsk->sighand->siglock);
634	}
635	return signr;
636	}
637
638	/*
639	* Tell a process that it has a new active signal..
640	*
641	* NOTE! we rely on the previous spin_lock to
642	* lock interrupts for us! We can only be called with
643	* "siglock" held, and the local interrupt must
644	* have been disabled when that got acquired!
645	*
646	* No need to set need_resched since signal event passing
647	* goes through ->blocked
648	*/
649	void signal_wake_up_state(struct task_struct *t, unsigned int state)
650	{
651	set_tsk_thread_flag(t, TIF_SIGPENDING);
652	/*
653	* TASK_WAKEKILL also means wake it up in the stopped/traced/killable
654	* case. We don't check t->state here because there is a race with it
655	* executing another processor and just now entering stopped state.
656	* By using wake_up_state, we ensure the process will wake up and
657	* handle its death signal.
658	*/
659	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
660	kick_process(t);
661	}
662
663	/*
664	* Remove signals in mask from the pending set and queue.
665	* Returns 1 if any signals were found.
666	*
667	* All callers must be holding the siglock.
668	*/
669	static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
670	{
671	struct sigqueue *q, *n;
672	sigset_t m;
673
674	sigandsets(&m, mask, &s->signal);
675	if (sigisemptyset(&m))
676	return 0;
677
678	sigandnsets(&s->signal, &s->signal, mask);
679	list_for_each_entry_safe(q, n, &s->list, list) {
680	if (sigismember(mask, q->info.si_signo)) {
681	list_del_init(&q->list);
682	__sigqueue_free(q);
683	}
684	}
685	return 1;
686	}
687
688	static inline int is_si_special(const struct siginfo *info)
689	{
690	return info <= SEND_SIG_FORCED;
691	}
692
693	static inline bool si_fromuser(const struct siginfo *info)
694	{
695	return info == SEND_SIG_NOINFO ||
696	(!is_si_special(info) && SI_FROMUSER(info));
697	}
698
699	static int dequeue_synchronous_signal(siginfo_t *info)
700	{
701	struct task_struct *tsk = current;
702	struct sigpending *pending = &tsk->pending;
703	struct sigqueue *q, *sync = NULL;
704
705	/*
706	* Might a synchronous signal be in the queue?
707	*/
708	if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
709	return 0;
710
711	/*
712	* Return the first synchronous signal in the queue.
713	*/
714	list_for_each_entry(q, &pending->list, list) {
715	/* Synchronous signals have a postive si_code */
716	if ((q->info.si_code > SI_USER) &&
717	(sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
718	sync = q;
719	goto next;
720	}
721	}
722	return 0;
723	next:
724	/*
725	* Check if there is another siginfo for the same signal.
726	*/
727	list_for_each_entry_continue(q, &pending->list, list) {
728	if (q->info.si_signo == sync->info.si_signo)
729	goto still_pending;
730	}
731
732	sigdelset(&pending->signal, sync->info.si_signo);
733	recalc_sigpending();
734	still_pending:
735	list_del_init(&sync->list);
736	copy_siginfo(info, &sync->info);
737	__sigqueue_free(sync);
738	return info->si_signo;
739	}
740
741	/*
742	* called with RCU read lock from check_kill_permission()
743	*/
744	static int kill_ok_by_cred(struct task_struct *t)
745	{
746	const struct cred *cred = current_cred();
747	const struct cred *tcred = __task_cred(t);
748
749	if (uid_eq(cred->euid, tcred->suid) ||
750	uid_eq(cred->euid, tcred->uid) ||
751	uid_eq(cred->uid, tcred->suid) ||
752	uid_eq(cred->uid, tcred->uid))
753	return 1;
754
755	if (ns_capable(tcred->user_ns, CAP_KILL))
756	return 1;
757
758	return 0;
759	}
760
761	/*
762	* Bad permissions for sending the signal
763	* - the caller must hold the RCU read lock
764	*/
765	static int check_kill_permission(int sig, struct siginfo *info,
766	struct task_struct *t)
767	{
768	struct pid *sid;
769	int error;
770
771	if (!valid_signal(sig))
772	return -EINVAL;
773
774	if (!si_fromuser(info))
775	return 0;
776
777	error = audit_signal_info(sig, t); /* Let audit system see the signal */
778	if (error)
779	return error;
780
781	if (!same_thread_group(current, t) &&
782	!kill_ok_by_cred(t)) {
783	switch (sig) {
784	case SIGCONT:
785	sid = task_session(t);
786	/*
787	* We don't return the error if sid == NULL. The
788	* task was unhashed, the caller must notice this.
789	*/
790	if (!sid || sid == task_session(current))
791	break;
792	default:
793	return -EPERM;
794	}
795	}
796
797	return security_task_kill(t, info, sig, 0);
798	}
799
800	/**
801	* ptrace_trap_notify - schedule trap to notify ptracer
802	* @t: tracee wanting to notify tracer
803	*
804	* This function schedules sticky ptrace trap which is cleared on the next
805	* TRAP_STOP to notify ptracer of an event. @t must have been seized by
806	* ptracer.
807	*
808	* If @t is running, STOP trap will be taken. If trapped for STOP and
809	* ptracer is listening for events, tracee is woken up so that it can
810	* re-trap for the new event. If trapped otherwise, STOP trap will be
811	* eventually taken without returning to userland after the existing traps
812	* are finished by PTRACE_CONT.
813	*
814	* CONTEXT:
815	* Must be called with @task->sighand->siglock held.
816	*/
817	static void ptrace_trap_notify(struct task_struct *t)
818	{
819	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
820	assert_spin_locked(&t->sighand->siglock);
821
822	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
823	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
824	}
825
826	/*
827	* Handle magic process-wide effects of stop/continue signals. Unlike
828	* the signal actions, these happen immediately at signal-generation
829	* time regardless of blocking, ignoring, or handling. This does the
830	* actual continuing for SIGCONT, but not the actual stopping for stop
831	* signals. The process stop is done as a signal action for SIG_DFL.
832	*
833	* Returns true if the signal should be actually delivered, otherwise
834	* it should be dropped.
835	*/
836	static bool prepare_signal(int sig, struct task_struct *p, bool force)
837	{
838	struct signal_struct *signal = p->signal;
839	struct task_struct *t;
840	sigset_t flush;
841
842	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
843	if (!(signal->flags & SIGNAL_GROUP_EXIT))
844	return sig == SIGKILL;
845	/*
846	* The process is in the middle of dying, nothing to do.
847	*/
848	} else if (sig_kernel_stop(sig)) {
849	/*
850	* This is a stop signal. Remove SIGCONT from all queues.
851	*/
852	siginitset(&flush, sigmask(SIGCONT));
853	flush_sigqueue_mask(&flush, &signal->shared_pending);
854	for_each_thread(p, t)
855	flush_sigqueue_mask(&flush, &t->pending);
856	} else if (sig == SIGCONT) {
857	unsigned int why;
858	/*
859	* Remove all stop signals from all queues, wake all threads.
860	*/
861	siginitset(&flush, SIG_KERNEL_STOP_MASK);
862	flush_sigqueue_mask(&flush, &signal->shared_pending);
863	for_each_thread(p, t) {
864	flush_sigqueue_mask(&flush, &t->pending);
865	task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
866	if (likely(!(t->ptrace & PT_SEIZED)))
867	wake_up_state(t, __TASK_STOPPED);
868	else
869	ptrace_trap_notify(t);
870	}
871
872	/*
873	* Notify the parent with CLD_CONTINUED if we were stopped.
874	*
875	* If we were in the middle of a group stop, we pretend it
876	* was already finished, and then continued. Since SIGCHLD
877	* doesn't queue we report only CLD_STOPPED, as if the next
878	* CLD_CONTINUED was dropped.
879	*/
880	why = 0;
881	if (signal->flags & SIGNAL_STOP_STOPPED)
882	why |= SIGNAL_CLD_CONTINUED;
883	else if (signal->group_stop_count)
884	why |= SIGNAL_CLD_STOPPED;
885
886	if (why) {
887	/*
888	* The first thread which returns from do_signal_stop()
889	* will take ->siglock, notice SIGNAL_CLD_MASK, and
890	* notify its parent. See get_signal_to_deliver().
891	*/
892	signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
893	signal->group_stop_count = 0;
894	signal->group_exit_code = 0;
895	}
896	}
897
898	return !sig_ignored(p, sig, force);
899	}
900
901	/*
902	* Test if P wants to take SIG. After we've checked all threads with this,
903	* it's equivalent to finding no threads not blocking SIG. Any threads not
904	* blocking SIG were ruled out because they are not running and already
905	* have pending signals. Such threads will dequeue from the shared queue
906	* as soon as they're available, so putting the signal on the shared queue
907	* will be equivalent to sending it to one such thread.
908	*/
909	static inline int wants_signal(int sig, struct task_struct *p)
910	{
911	if (sigismember(&p->blocked, sig))
912	return 0;
913	if (p->flags & PF_EXITING)
914	return 0;
915	if (sig == SIGKILL)
916	return 1;
917	if (task_is_stopped_or_traced(p))
918	return 0;
919	return task_curr(p) || !signal_pending(p);
920	}
921
922	static void complete_signal(int sig, struct task_struct *p, int group)
923	{
924	struct signal_struct *signal = p->signal;
925	struct task_struct *t;
926
927	/*
928	* Now find a thread we can wake up to take the signal off the queue.
929	*
930	* If the main thread wants the signal, it gets first crack.
931	* Probably the least surprising to the average bear.
932	*/
933	if (wants_signal(sig, p))
934	t = p;
935	else if (!group || thread_group_empty(p))
936	/*
937	* There is just one thread and it does not need to be woken.
938	* It will dequeue unblocked signals before it runs again.
939	*/
940	return;
941	else {
942	/*
943	* Otherwise try to find a suitable thread.
944	*/
945	t = signal->curr_target;
946	while (!wants_signal(sig, t)) {
947	t = next_thread(t);
948	if (t == signal->curr_target)
949	/*
950	* No thread needs to be woken.
951	* Any eligible threads will see
952	* the signal in the queue soon.
953	*/
954	return;
955	}
956	signal->curr_target = t;
957	}
958
959	/*
960	* Found a killable thread. If the signal will be fatal,
961	* then start taking the whole group down immediately.
962	*/
963	if (sig_fatal(p, sig) &&
964	!(signal->flags & SIGNAL_GROUP_EXIT) &&
965	!sigismember(&t->real_blocked, sig) &&
966	(sig == SIGKILL || !p->ptrace)) {
967	/*
968	* This signal will be fatal to the whole group.
969	*/
970	if (!sig_kernel_coredump(sig)) {
971	/*
972	* Start a group exit and wake everybody up.
973	* This way we don't have other threads
974	* running and doing things after a slower
975	* thread has the fatal signal pending.
976	*/
977	signal->flags = SIGNAL_GROUP_EXIT;
978	signal->group_exit_code = sig;
979	signal->group_stop_count = 0;
980	t = p;
981	do {
982	task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
983	sigaddset(&t->pending.signal, SIGKILL);
984	signal_wake_up(t, 1);
985	} while_each_thread(p, t);
986	return;
987	}
988	}
989
990	/*
991	* The signal is already in the shared-pending queue.
992	* Tell the chosen thread to wake up and dequeue it.
993	*/
994	signal_wake_up(t, sig == SIGKILL);
995	return;
996	}
997
998	static inline int legacy_queue(struct sigpending *signals, int sig)
999	{
1000	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1001	}
1002
1003	#ifdef CONFIG_USER_NS
1004	static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1005	{
1006	if (current_user_ns() == task_cred_xxx(t, user_ns))
1007	return;
1008
1009	if (SI_FROMKERNEL(info))
1010	return;
1011
1012	rcu_read_lock();
1013	info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1014	make_kuid(current_user_ns(), info->si_uid));
1015	rcu_read_unlock();
1016	}
1017	#else
1018	static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1019	{
1020	return;
1021	}
1022	#endif
1023
1024	static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1025	int group, int from_ancestor_ns)
1026	{
1027	struct sigpending *pending;
1028	struct sigqueue *q;
1029	int override_rlimit;
1030	int ret = 0, result;
1031
1032	assert_spin_locked(&t->sighand->siglock);
1033
1034	result = TRACE_SIGNAL_IGNORED;
1035	if (!prepare_signal(sig, t,
1036	from_ancestor_ns || (info == SEND_SIG_PRIV) || (info == SEND_SIG_FORCED)))
1037	goto ret;
1038
1039	pending = group ? &t->signal->shared_pending : &t->pending;
1040	/*
1041	* Short-circuit ignored signals and support queuing
1042	* exactly one non-rt signal, so that we can get more
1043	* detailed information about the cause of the signal.
1044	*/
1045	result = TRACE_SIGNAL_ALREADY_PENDING;
1046	if (legacy_queue(pending, sig))
1047	goto ret;
1048
1049	result = TRACE_SIGNAL_DELIVERED;
1050	/*
1051	* fast-pathed signals for kernel-internal things like SIGSTOP
1052	* or SIGKILL.
1053	*/
1054	if (info == SEND_SIG_FORCED)
1055	goto out_set;
1056
1057	/*
1058	* Real-time signals must be queued if sent by sigqueue, or
1059	* some other real-time mechanism. It is implementation
1060	* defined whether kill() does so. We attempt to do so, on
1061	* the principle of least surprise, but since kill is not
1062	* allowed to fail with EAGAIN when low on memory we just
1063	* make sure at least one signal gets delivered and don't
1064	* pass on the info struct.
1065	*/
1066	if (sig < SIGRTMIN)
1067	override_rlimit = (is_si_special(info) || info->si_code >= 0);
1068	else
1069	override_rlimit = 0;
1070
1071	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1072	override_rlimit);
1073	if (q) {
1074	list_add_tail(&q->list, &pending->list);
1075	switch ((unsigned long) info) {
1076	case (unsigned long) SEND_SIG_NOINFO:
1077	q->info.si_signo = sig;
1078	q->info.si_errno = 0;
1079	q->info.si_code = SI_USER;
1080	q->info.si_pid = task_tgid_nr_ns(current,
1081	task_active_pid_ns(t));
1082	q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1083	break;
1084	case (unsigned long) SEND_SIG_PRIV:
1085	q->info.si_signo = sig;
1086	q->info.si_errno = 0;
1087	q->info.si_code = SI_KERNEL;
1088	q->info.si_pid = 0;
1089	q->info.si_uid = 0;
1090	break;
1091	default:
1092	copy_siginfo(&q->info, info);
1093	if (from_ancestor_ns)
1094	q->info.si_pid = 0;
1095	break;
1096	}
1097
1098	userns_fixup_signal_uid(&q->info, t);
1099
1100	} else if (!is_si_special(info)) {
1101	if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1102	/*
1103	* Queue overflow, abort. We may abort if the
1104	* signal was rt and sent by user using something
1105	* other than kill().
1106	*/
1107	result = TRACE_SIGNAL_OVERFLOW_FAIL;
1108	ret = -EAGAIN;
1109	goto ret;
1110	} else {
1111	/*
1112	* This is a silent loss of information. We still
1113	* send the signal, but the *info bits are lost.
1114	*/
1115	result = TRACE_SIGNAL_LOSE_INFO;
1116	}
1117	}
1118
1119	out_set:
1120	signalfd_notify(t, sig);
1121	sigaddset(&pending->signal, sig);
1122	complete_signal(sig, t, group);
1123	ret:
1124	trace_signal_generate(sig, info, t, group, result);
1125	return ret;
1126	}
1127
1128	static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1129	int group)
1130	{
1131	int from_ancestor_ns = 0;
1132
1133	#ifdef CONFIG_PID_NS
1134	from_ancestor_ns = si_fromuser(info) &&
1135	!task_pid_nr_ns(current, task_active_pid_ns(t));
1136	#endif
1137
1138	return __send_signal(sig, info, t, group, from_ancestor_ns);
1139	}
1140
1141	static void print_fatal_signal(int signr)
1142	{
1143	struct pt_regs *regs = signal_pt_regs();
1144	pr_info("potentially unexpected fatal signal %d.\n", signr);
1145
1146	#if defined(__i386__) && !defined(__arch_um__)
1147	pr_info("code at %08lx: ", regs->ip);
1148	{
1149	int i;
1150	for (i = 0; i < 16; i++) {
1151	unsigned char insn;
1152
1153	if (get_user(insn, (unsigned char *)(regs->ip + i)))
1154	break;
1155	pr_cont("%02x ", insn);
1156	}
1157	}
1158	pr_cont("\n");
1159	#endif
1160	preempt_disable();
1161	show_regs(regs);
1162	preempt_enable();
1163	}
1164
1165	static int __init setup_print_fatal_signals(char *str)
1166	{
1167	get_option (&str, &print_fatal_signals);
1168
1169	return 1;
1170	}
1171
1172	__setup("print-fatal-signals=", setup_print_fatal_signals);
1173
1174	int
1175	__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1176	{
1177	return send_signal(sig, info, p, 1);
1178	}
1179
1180	static int
1181	specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1182	{
1183	return send_signal(sig, info, t, 0);
1184	}
1185
1186	int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1187	bool group)
1188	{
1189	unsigned long flags;
1190	int ret = -ESRCH;
1191
1192	if (lock_task_sighand(p, &flags)) {
1193	ret = send_signal(sig, info, p, group);
1194	unlock_task_sighand(p, &flags);
1195	}
1196
1197	return ret;
1198	}
1199
1200	/*
1201	* Force a signal that the process can't ignore: if necessary
1202	* we unblock the signal and change any SIG_IGN to SIG_DFL.
1203	*
1204	* Note: If we unblock the signal, we always reset it to SIG_DFL,
1205	* since we do not want to have a signal handler that was blocked
1206	* be invoked when user space had explicitly blocked it.
1207	*
1208	* We don't want to have recursive SIGSEGV's etc, for example,
1209	* that is why we also clear SIGNAL_UNKILLABLE.
1210	*/
1211	int
1212	force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1213	{
1214	unsigned long int flags;
1215	int ret, blocked, ignored;
1216	struct k_sigaction *action;
1217
1218	spin_lock_irqsave(&t->sighand->siglock, flags);
1219	action = &t->sighand->action[sig-1];
1220	ignored = action->sa.sa_handler == SIG_IGN;
1221	blocked = sigismember(&t->blocked, sig);
1222	if (blocked || ignored) {
1223	action->sa.sa_handler = SIG_DFL;
1224	if (blocked) {
1225	sigdelset(&t->blocked, sig);
1226	recalc_sigpending_and_wake(t);
1227	}
1228	}
1229	if (action->sa.sa_handler == SIG_DFL)
1230	t->signal->flags &= ~SIGNAL_UNKILLABLE;
1231	ret = specific_send_sig_info(sig, info, t);
1232	spin_unlock_irqrestore(&t->sighand->siglock, flags);
1233
1234	return ret;
1235	}
1236
1237	/*
1238	* Nuke all other threads in the group.
1239	*/
1240	int zap_other_threads(struct task_struct *p)
1241	{
1242	struct task_struct *t = p;
1243	int count = 0;
1244
1245	p->signal->group_stop_count = 0;
1246
1247	while_each_thread(p, t) {
1248	task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1249	count++;
1250
1251	/* Don't bother with already dead threads */
1252	if (t->exit_state)
1253	continue;
1254	sigaddset(&t->pending.signal, SIGKILL);
1255	signal_wake_up(t, 1);
1256	}
1257
1258	return count;
1259	}
1260
1261	struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1262	unsigned long *flags)
1263	{
1264	struct sighand_struct *sighand;
1265
1266	for (;;) {
1267	/*
1268	* Disable interrupts early to avoid deadlocks.
1269	* See rcu_read_unlock() comment header for details.
1270	*/
1271	local_irq_save(*flags);
1272	rcu_read_lock();
1273	sighand = rcu_dereference(tsk->sighand);
1274	if (unlikely(sighand == NULL)) {
1275	rcu_read_unlock();
1276	local_irq_restore(*flags);
1277	break;
1278	}
1279	/*
1280	* This sighand can be already freed and even reused, but
1281	* we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1282	* initializes ->siglock: this slab can't go away, it has
1283	* the same object type, ->siglock can't be reinitialized.
1284	*
1285	* We need to ensure that tsk->sighand is still the same
1286	* after we take the lock, we can race with de_thread() or
1287	* __exit_signal(). In the latter case the next iteration
1288	* must see ->sighand == NULL.
1289	*/
1290	spin_lock(&sighand->siglock);
1291	if (likely(sighand == tsk->sighand)) {
1292	rcu_read_unlock();
1293	break;
1294	}
1295	spin_unlock(&sighand->siglock);
1296	rcu_read_unlock();
1297	local_irq_restore(*flags);
1298	}
1299
1300	return sighand;
1301	}
1302
1303	/*
1304	* send signal info to all the members of a group
1305	*/
1306	int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1307	{
1308	int ret;
1309
1310	rcu_read_lock();
1311	ret = check_kill_permission(sig, info, p);
1312	rcu_read_unlock();
1313
1314	if (!ret && sig)
1315	ret = do_send_sig_info(sig, info, p, true);
1316
1317	return ret;
1318	}
1319
1320	/*
1321	* __kill_pgrp_info() sends a signal to a process group: this is what the tty
1322	* control characters do (^C, ^Z etc)
1323	* - the caller must hold at least a readlock on tasklist_lock
1324	*/
1325	int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1326	{
1327	struct task_struct *p = NULL;
1328	int retval, success;
1329
1330	success = 0;
1331	retval = -ESRCH;
1332	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1333	int err = group_send_sig_info(sig, info, p);
1334	success |= !err;
1335	retval = err;
1336	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1337	return success ? 0 : retval;
1338	}
1339
1340	int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1341	{
1342	int error = -ESRCH;
1343	struct task_struct *p;
1344
1345	for (;;) {
1346	rcu_read_lock();
1347	p = pid_task(pid, PIDTYPE_PID);
1348	if (p)
1349	error = group_send_sig_info(sig, info, p);
1350	rcu_read_unlock();
1351	if (likely(!p || error != -ESRCH))
1352	return error;
1353
1354	/*
1355	* The task was unhashed in between, try again. If it
1356	* is dead, pid_task() will return NULL, if we race with
1357	* de_thread() it will find the new leader.
1358	*/
1359	}
1360	}
1361
1362	int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1363	{
1364	int error;
1365	rcu_read_lock();
1366	error = kill_pid_info(sig, info, find_vpid(pid));
1367	rcu_read_unlock();
1368	return error;
1369	}
1370
1371	static int kill_as_cred_perm(const struct cred *cred,
1372	struct task_struct *target)
1373	{
1374	const struct cred *pcred = __task_cred(target);
1375	if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1376	!uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
1377	return 0;
1378	return 1;
1379	}
1380
1381	/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1382	int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1383	const struct cred *cred, u32 secid)
1384	{
1385	int ret = -EINVAL;
1386	struct task_struct *p;
1387	unsigned long flags;
1388
1389	if (!valid_signal(sig))
1390	return ret;
1391
1392	rcu_read_lock();
1393	p = pid_task(pid, PIDTYPE_PID);
1394	if (!p) {
1395	ret = -ESRCH;
1396	goto out_unlock;
1397	}
1398	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1399	ret = -EPERM;
1400	goto out_unlock;
1401	}
1402	ret = security_task_kill(p, info, sig, secid);
1403	if (ret)
1404	goto out_unlock;
1405
1406	if (sig) {
1407	if (lock_task_sighand(p, &flags)) {
1408	ret = __send_signal(sig, info, p, 1, 0);
1409	unlock_task_sighand(p, &flags);
1410	} else
1411	ret = -ESRCH;
1412	}
1413	out_unlock:
1414	rcu_read_unlock();
1415	return ret;
1416	}
1417	EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1418
1419	/*
1420	* kill_something_info() interprets pid in interesting ways just like kill(2).
1421	*
1422	* POSIX specifies that kill(-1,sig) is unspecified, but what we have
1423	* is probably wrong. Should make it like BSD or SYSV.
1424	*/
1425
1426	static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1427	{
1428	int ret;
1429
1430	if (pid > 0) {
1431	rcu_read_lock();
1432	ret = kill_pid_info(sig, info, find_vpid(pid));
1433	rcu_read_unlock();
1434	return ret;
1435	}
1436
1437	/* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1438	if (pid == INT_MIN)
1439	return -ESRCH;
1440
1441	read_lock(&tasklist_lock);
1442	if (pid != -1) {
1443	ret = __kill_pgrp_info(sig, info,
1444	pid ? find_vpid(-pid) : task_pgrp(current));
1445	} else {
1446	int retval = 0, count = 0;
1447	struct task_struct * p;
1448
1449	for_each_process(p) {
1450	if (task_pid_vnr(p) > 1 &&
1451	!same_thread_group(p, current)) {
1452	int err = group_send_sig_info(sig, info, p);
1453	++count;
1454	if (err != -EPERM)
1455	retval = err;
1456	}
1457	}
1458	ret = count ? retval : -ESRCH;
1459	}
1460	read_unlock(&tasklist_lock);
1461
1462	return ret;
1463	}
1464
1465	/*
1466	* These are for backward compatibility with the rest of the kernel source.
1467	*/
1468
1469	int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1470	{
1471	/*
1472	* Make sure legacy kernel users don't send in bad values
1473	* (normal paths check this in check_kill_permission).
1474	*/
1475	if (!valid_signal(sig))
1476	return -EINVAL;
1477
1478	return do_send_sig_info(sig, info, p, false);
1479	}
1480
1481	#define __si_special(priv) \
1482	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1483
1484	int
1485	send_sig(int sig, struct task_struct *p, int priv)
1486	{
1487	return send_sig_info(sig, __si_special(priv), p);
1488	}
1489
1490	void
1491	force_sig(int sig, struct task_struct *p)
1492	{
1493	force_sig_info(sig, SEND_SIG_PRIV, p);
1494	}
1495
1496	/*
1497	* When things go south during signal handling, we
1498	* will force a SIGSEGV. And if the signal that caused
1499	* the problem was already a SIGSEGV, we'll want to
1500	* make sure we don't even try to deliver the signal..
1501	*/
1502	int
1503	force_sigsegv(int sig, struct task_struct *p)
1504	{
1505	if (sig == SIGSEGV) {
1506	unsigned long flags;
1507	spin_lock_irqsave(&p->sighand->siglock, flags);
1508	p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1509	spin_unlock_irqrestore(&p->sighand->siglock, flags);
1510	}
1511	force_sig(SIGSEGV, p);
1512	return 0;
1513	}
1514
1515	int kill_pgrp(struct pid *pid, int sig, int priv)
1516	{
1517	int ret;
1518
1519	read_lock(&tasklist_lock);
1520	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1521	read_unlock(&tasklist_lock);
1522
1523	return ret;
1524	}
1525	EXPORT_SYMBOL(kill_pgrp);
1526
1527	int kill_pid(struct pid *pid, int sig, int priv)
1528	{
1529	return kill_pid_info(sig, __si_special(priv), pid);
1530	}
1531	EXPORT_SYMBOL(kill_pid);
1532
1533	/*
1534	* These functions support sending signals using preallocated sigqueue
1535	* structures. This is needed "because realtime applications cannot
1536	* afford to lose notifications of asynchronous events, like timer
1537	* expirations or I/O completions". In the case of POSIX Timers
1538	* we allocate the sigqueue structure from the timer_create. If this
1539	* allocation fails we are able to report the failure to the application
1540	* with an EAGAIN error.
1541	*/
1542	struct sigqueue *sigqueue_alloc(void)
1543	{
1544	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1545
1546	if (q)
1547	q->flags |= SIGQUEUE_PREALLOC;
1548
1549	return q;
1550	}
1551
1552	void sigqueue_free(struct sigqueue *q)
1553	{
1554	unsigned long flags;
1555	spinlock_t *lock = &current->sighand->siglock;
1556
1557	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1558	/*
1559	* We must hold ->siglock while testing q->list
1560	* to serialize with collect_signal() or with
1561	* __exit_signal()->flush_sigqueue().
1562	*/
1563	spin_lock_irqsave(lock, flags);
1564	q->flags &= ~SIGQUEUE_PREALLOC;
1565	/*
1566	* If it is queued it will be freed when dequeued,
1567	* like the "regular" sigqueue.
1568	*/
1569	if (!list_empty(&q->list))
1570	q = NULL;
1571	spin_unlock_irqrestore(lock, flags);
1572
1573	if (q)
1574	__sigqueue_free(q);
1575	}
1576
1577	int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1578	{
1579	int sig = q->info.si_signo;
1580	struct sigpending *pending;
1581	unsigned long flags;
1582	int ret, result;
1583
1584	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1585
1586	ret = -1;
1587	if (!likely(lock_task_sighand(t, &flags)))
1588	goto ret;
1589
1590	ret = 1; /* the signal is ignored */
1591	result = TRACE_SIGNAL_IGNORED;
1592	if (!prepare_signal(sig, t, false))
1593	goto out;
1594
1595	ret = 0;
1596	if (unlikely(!list_empty(&q->list))) {
1597	/*
1598	* If an SI_TIMER entry is already queue just increment
1599	* the overrun count.
1600	*/
1601	BUG_ON(q->info.si_code != SI_TIMER);
1602	q->info.si_overrun++;
1603	result = TRACE_SIGNAL_ALREADY_PENDING;
1604	goto out;
1605	}
1606	q->info.si_overrun = 0;
1607
1608	signalfd_notify(t, sig);
1609	pending = group ? &t->signal->shared_pending : &t->pending;
1610	list_add_tail(&q->list, &pending->list);
1611	sigaddset(&pending->signal, sig);
1612	complete_signal(sig, t, group);
1613	result = TRACE_SIGNAL_DELIVERED;
1614	out:
1615	trace_signal_generate(sig, &q->info, t, group, result);
1616	unlock_task_sighand(t, &flags);
1617	ret:
1618	return ret;
1619	}
1620
1621	/*
1622	* Let a parent know about the death of a child.
1623	* For a stopped/continued status change, use do_notify_parent_cldstop instead.
1624	*
1625	* Returns true if our parent ignored us and so we've switched to
1626	* self-reaping.
1627	*/
1628	bool do_notify_parent(struct task_struct *tsk, int sig)
1629	{
1630	struct siginfo info;
1631	unsigned long flags;
1632	struct sighand_struct *psig;
1633	bool autoreap = false;
1634	cputime_t utime, stime;
1635
1636	BUG_ON(sig == -1);
1637
1638	/* do_notify_parent_cldstop should have been called instead. */
1639	BUG_ON(task_is_stopped_or_traced(tsk));
1640
1641	BUG_ON(!tsk->ptrace &&
1642	(tsk->group_leader != tsk || !thread_group_empty(tsk)));
1643
1644	if (sig != SIGCHLD) {
1645	/*
1646	* This is only possible if parent == real_parent.
1647	* Check if it has changed security domain.
1648	*/
1649	if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1650	sig = SIGCHLD;
1651	}
1652
1653	info.si_signo = sig;
1654	info.si_errno = 0;
1655	/*
1656	* We are under tasklist_lock here so our parent is tied to
1657	* us and cannot change.
1658	*
1659	* task_active_pid_ns will always return the same pid namespace
1660	* until a task passes through release_task.
1661	*
1662	* write_lock() currently calls preempt_disable() which is the
1663	* same as rcu_read_lock(), but according to Oleg, this is not
1664	* correct to rely on this
1665	*/
1666	rcu_read_lock();
1667	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1668	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1669	task_uid(tsk));
1670	rcu_read_unlock();
1671
1672	task_cputime(tsk, &utime, &stime);
1673	info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1674	info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1675
1676	info.si_status = tsk->exit_code & 0x7f;
1677	if (tsk->exit_code & 0x80)
1678	info.si_code = CLD_DUMPED;
1679	else if (tsk->exit_code & 0x7f)
1680	info.si_code = CLD_KILLED;
1681	else {
1682	info.si_code = CLD_EXITED;
1683	info.si_status = tsk->exit_code >> 8;
1684	}
1685
1686	psig = tsk->parent->sighand;
1687	spin_lock_irqsave(&psig->siglock, flags);
1688	if (!tsk->ptrace && sig == SIGCHLD &&
1689	(psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1690	(psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1691	/*
1692	* We are exiting and our parent doesn't care. POSIX.1
1693	* defines special semantics for setting SIGCHLD to SIG_IGN
1694	* or setting the SA_NOCLDWAIT flag: we should be reaped
1695	* automatically and not left for our parent's wait4 call.
1696	* Rather than having the parent do it as a magic kind of
1697	* signal handler, we just set this to tell do_exit that we
1698	* can be cleaned up without becoming a zombie. Note that
1699	* we still call __wake_up_parent in this case, because a
1700	* blocked sys_wait4 might now return -ECHILD.
1701	*
1702	* Whether we send SIGCHLD or not for SA_NOCLDWAIT
1703	* is implementation-defined: we do (if you don't want
1704	* it, just use SIG_IGN instead).
1705	*/
1706	autoreap = true;
1707	if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1708	sig = 0;
1709	}
1710	if (valid_signal(sig) && sig)
1711	__group_send_sig_info(sig, &info, tsk->parent);
1712	__wake_up_parent(tsk, tsk->parent);
1713	spin_unlock_irqrestore(&psig->siglock, flags);
1714
1715	return autoreap;
1716	}
1717
1718	/**
1719	* do_notify_parent_cldstop - notify parent of stopped/continued state change
1720	* @tsk: task reporting the state change
1721	* @for_ptracer: the notification is for ptracer
1722	* @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1723	*
1724	* Notify @tsk's parent that the stopped/continued state has changed. If
1725	* @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1726	* If %true, @tsk reports to @tsk->parent which should be the ptracer.
1727	*
1728	* CONTEXT:
1729	* Must be called with tasklist_lock at least read locked.
1730	*/
1731	static void do_notify_parent_cldstop(struct task_struct *tsk,
1732	bool for_ptracer, int why)
1733	{
1734	struct siginfo info;
1735	unsigned long flags;
1736	struct task_struct *parent;
1737	struct sighand_struct *sighand;
1738	cputime_t utime, stime;
1739
1740	if (for_ptracer) {
1741	parent = tsk->parent;
1742	} else {
1743	tsk = tsk->group_leader;
1744	parent = tsk->real_parent;
1745	}
1746
1747	info.si_signo = SIGCHLD;
1748	info.si_errno = 0;
1749	/*
1750	* see comment in do_notify_parent() about the following 4 lines
1751	*/
1752	rcu_read_lock();
1753	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1754	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1755	rcu_read_unlock();
1756
1757	task_cputime(tsk, &utime, &stime);
1758	info.si_utime = cputime_to_clock_t(utime);
1759	info.si_stime = cputime_to_clock_t(stime);
1760
1761	info.si_code = why;
1762	switch (why) {
1763	case CLD_CONTINUED:
1764	info.si_status = SIGCONT;
1765	break;
1766	case CLD_STOPPED:
1767	info.si_status = tsk->signal->group_exit_code & 0x7f;
1768	break;
1769	case CLD_TRAPPED:
1770	info.si_status = tsk->exit_code & 0x7f;
1771	break;
1772	default:
1773	BUG();
1774	}
1775
1776	sighand = parent->sighand;
1777	spin_lock_irqsave(&sighand->siglock, flags);
1778	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1779	!(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1780	__group_send_sig_info(SIGCHLD, &info, parent);
1781	/*
1782	* Even if SIGCHLD is not generated, we must wake up wait4 calls.
1783	*/
1784	__wake_up_parent(tsk, parent);
1785	spin_unlock_irqrestore(&sighand->siglock, flags);
1786	}
1787
1788	static inline int may_ptrace_stop(void)
1789	{
1790	if (!likely(current->ptrace))
1791	return 0;
1792	/*
1793	* Are we in the middle of do_coredump?
1794	* If so and our tracer is also part of the coredump stopping
1795	* is a deadlock situation, and pointless because our tracer
1796	* is dead so don't allow us to stop.
1797	* If SIGKILL was already sent before the caller unlocked
1798	* ->siglock we must see ->core_state != NULL. Otherwise it
1799	* is safe to enter schedule().
1800	*
1801	* This is almost outdated, a task with the pending SIGKILL can't
1802	* block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1803	* after SIGKILL was already dequeued.
1804	*/
1805	if (unlikely(current->mm->core_state) &&
1806	unlikely(current->mm == current->parent->mm))
1807	return 0;
1808
1809	return 1;
1810	}
1811
1812	/*
1813	* Return non-zero if there is a SIGKILL that should be waking us up.
1814	* Called with the siglock held.
1815	*/
1816	static int sigkill_pending(struct task_struct *tsk)
1817	{
1818	return sigismember(&tsk->pending.signal, SIGKILL) ||
1819	sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1820	}
1821
1822	/*
1823	* This must be called with current->sighand->siglock held.
1824	*
1825	* This should be the path for all ptrace stops.
1826	* We always set current->last_siginfo while stopped here.
1827	* That makes it a way to test a stopped process for
1828	* being ptrace-stopped vs being job-control-stopped.
1829	*
1830	* If we actually decide not to stop at all because the tracer
1831	* is gone, we keep current->exit_code unless clear_code.
1832	*/
1833	static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1834	__releases(&current->sighand->siglock)
1835	__acquires(&current->sighand->siglock)
1836	{
1837	bool gstop_done = false;
1838
1839	if (arch_ptrace_stop_needed(exit_code, info)) {
1840	/*
1841	* The arch code has something special to do before a
1842	* ptrace stop. This is allowed to block, e.g. for faults
1843	* on user stack pages. We can't keep the siglock while
1844	* calling arch_ptrace_stop, so we must release it now.
1845	* To preserve proper semantics, we must do this before
1846	* any signal bookkeeping like checking group_stop_count.
1847	* Meanwhile, a SIGKILL could come in before we retake the
1848	* siglock. That must prevent us from sleeping in TASK_TRACED.
1849	* So after regaining the lock, we must check for SIGKILL.
1850	*/
1851	spin_unlock_irq(&current->sighand->siglock);
1852	arch_ptrace_stop(exit_code, info);
1853	spin_lock_irq(&current->sighand->siglock);
1854	if (sigkill_pending(current))
1855	return;
1856	}
1857
1858	/*
1859	* We're committing to trapping. TRACED should be visible before
1860	* TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1861	* Also, transition to TRACED and updates to ->jobctl should be
1862	* atomic with respect to siglock and should be done after the arch
1863	* hook as siglock is released and regrabbed across it.
1864	*/
1865	set_current_state(TASK_TRACED);
1866
1867	current->last_siginfo = info;
1868	current->exit_code = exit_code;
1869
1870	/*
1871	* If @why is CLD_STOPPED, we're trapping to participate in a group
1872	* stop. Do the bookkeeping. Note that if SIGCONT was delievered
1873	* across siglock relocks since INTERRUPT was scheduled, PENDING
1874	* could be clear now. We act as if SIGCONT is received after
1875	* TASK_TRACED is entered - ignore it.
1876	*/
1877	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1878	gstop_done = task_participate_group_stop(current);
1879
1880	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1881	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1882	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1883	task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1884
1885	/* entering a trap, clear TRAPPING */
1886	task_clear_jobctl_trapping(current);
1887
1888	spin_unlock_irq(&current->sighand->siglock);
1889	read_lock(&tasklist_lock);
1890	if (may_ptrace_stop()) {
1891	/*
1892	* Notify parents of the stop.
1893	*
1894	* While ptraced, there are two parents - the ptracer and
1895	* the real_parent of the group_leader. The ptracer should
1896	* know about every stop while the real parent is only
1897	* interested in the completion of group stop. The states
1898	* for the two don't interact with each other. Notify
1899	* separately unless they're gonna be duplicates.
1900	*/
1901	do_notify_parent_cldstop(current, true, why);
1902	if (gstop_done && ptrace_reparented(current))
1903	do_notify_parent_cldstop(current, false, why);
1904
1905	/*
1906	* Don't want to allow preemption here, because
1907	* sys_ptrace() needs this task to be inactive.
1908	*
1909	* XXX: implement read_unlock_no_resched().
1910	*/
1911	preempt_disable();
1912	read_unlock(&tasklist_lock);
1913	preempt_enable_no_resched();
1914	freezable_schedule();
1915	} else {
1916	/*
1917	* By the time we got the lock, our tracer went away.
1918	* Don't drop the lock yet, another tracer may come.
1919	*
1920	* If @gstop_done, the ptracer went away between group stop
1921	* completion and here. During detach, it would have set
1922	* JOBCTL_STOP_PENDING on us and we'll re-enter
1923	* TASK_STOPPED in do_signal_stop() on return, so notifying
1924	* the real parent of the group stop completion is enough.
1925	*/
1926	if (gstop_done)
1927	do_notify_parent_cldstop(current, false, why);
1928
1929	/* tasklist protects us from ptrace_freeze_traced() */
1930	__set_current_state(TASK_RUNNING);
1931	if (clear_code)
1932	current->exit_code = 0;
1933	read_unlock(&tasklist_lock);
1934	}
1935
1936	/*
1937	* We are back. Now reacquire the siglock before touching
1938	* last_siginfo, so that we are sure to have synchronized with
1939	* any signal-sending on another CPU that wants to examine it.
1940	*/
1941	spin_lock_irq(&current->sighand->siglock);
1942	current->last_siginfo = NULL;
1943
1944	/* LISTENING can be set only during STOP traps, clear it */
1945	current->jobctl &= ~JOBCTL_LISTENING;
1946
1947	/*
1948	* Queued signals ignored us while we were stopped for tracing.
1949	* So check for any that we should take before resuming user mode.
1950	* This sets TIF_SIGPENDING, but never clears it.
1951	*/
1952	recalc_sigpending_tsk(current);
1953	}
1954
1955	static void ptrace_do_notify(int signr, int exit_code, int why)
1956	{
1957	siginfo_t info;
1958
1959	memset(&info, 0, sizeof info);
1960	info.si_signo = signr;
1961	info.si_code = exit_code;
1962	info.si_pid = task_pid_vnr(current);
1963	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1964
1965	/* Let the debugger run. */
1966	ptrace_stop(exit_code, why, 1, &info);
1967	}
1968
1969	void ptrace_notify(int exit_code)
1970	{
1971	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1972	if (unlikely(current->task_works))
1973	task_work_run();
1974
1975	spin_lock_irq(&current->sighand->siglock);
1976	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1977	spin_unlock_irq(&current->sighand->siglock);
1978	}
1979
1980	/**
1981	* do_signal_stop - handle group stop for SIGSTOP and other stop signals
1982	* @signr: signr causing group stop if initiating
1983	*
1984	* If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1985	* and participate in it. If already set, participate in the existing
1986	* group stop. If participated in a group stop (and thus slept), %true is
1987	* returned with siglock released.
1988	*
1989	* If ptraced, this function doesn't handle stop itself. Instead,
1990	* %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1991	* untouched. The caller must ensure that INTERRUPT trap handling takes
1992	* places afterwards.
1993	*
1994	* CONTEXT:
1995	* Must be called with @current->sighand->siglock held, which is released
1996	* on %true return.
1997	*
1998	* RETURNS:
1999	* %false if group stop is already cancelled or ptrace trap is scheduled.
2000	* %true if participated in group stop.
2001	*/
2002	static bool do_signal_stop(int signr)
2003	__releases(&current->sighand->siglock)
2004	{
2005	struct signal_struct *sig = current->signal;
2006
2007	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2008	unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2009	struct task_struct *t;
2010
2011	/* signr will be recorded in task->jobctl for retries */
2012	WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2013
2014	if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2015	unlikely(signal_group_exit(sig)))
2016	return false;
2017	/*
2018	* There is no group stop already in progress. We must
2019	* initiate one now.
2020	*
2021	* While ptraced, a task may be resumed while group stop is
2022	* still in effect and then receive a stop signal and
2023	* initiate another group stop. This deviates from the
2024	* usual behavior as two consecutive stop signals can't
2025	* cause two group stops when !ptraced. That is why we
2026	* also check !task_is_stopped(t) below.
2027	*
2028	* The condition can be distinguished by testing whether
2029	* SIGNAL_STOP_STOPPED is already set. Don't generate
2030	* group_exit_code in such case.
2031	*
2032	* This is not necessary for SIGNAL_STOP_CONTINUED because
2033	* an intervening stop signal is required to cause two
2034	* continued events regardless of ptrace.
2035	*/
2036	if (!(sig->flags & SIGNAL_STOP_STOPPED))
2037	sig->group_exit_code = signr;
2038
2039	sig->group_stop_count = 0;
2040
2041	if (task_set_jobctl_pending(current, signr | gstop))
2042	sig->group_stop_count++;
2043
2044	t = current;
2045	while_each_thread(current, t) {
2046	/*
2047	* Setting state to TASK_STOPPED for a group
2048	* stop is always done with the siglock held,
2049	* so this check has no races.
2050	*/
2051	if (!task_is_stopped(t) &&
2052	task_set_jobctl_pending(t, signr | gstop)) {
2053	sig->group_stop_count++;
2054	if (likely(!(t->ptrace & PT_SEIZED)))
2055	signal_wake_up(t, 0);
2056	else
2057	ptrace_trap_notify(t);
2058	}
2059	}
2060	}
2061
2062	if (likely(!current->ptrace)) {
2063	int notify = 0;
2064
2065	/*
2066	* If there are no other threads in the group, or if there
2067	* is a group stop in progress and we are the last to stop,
2068	* report to the parent.
2069	*/
2070	if (task_participate_group_stop(current))
2071	notify = CLD_STOPPED;
2072
2073	__set_current_state(TASK_STOPPED);
2074	spin_unlock_irq(&current->sighand->siglock);
2075
2076	/*
2077	* Notify the parent of the group stop completion. Because
2078	* we're not holding either the siglock or tasklist_lock
2079	* here, ptracer may attach inbetween; however, this is for
2080	* group stop and should always be delivered to the real
2081	* parent of the group leader. The new ptracer will get
2082	* its notification when this task transitions into
2083	* TASK_TRACED.
2084	*/
2085	if (notify) {
2086	read_lock(&tasklist_lock);
2087	do_notify_parent_cldstop(current, false, notify);
2088	read_unlock(&tasklist_lock);
2089	}
2090
2091	/* Now we don't run again until woken by SIGCONT or SIGKILL */
2092	freezable_schedule();
2093	return true;
2094	} else {
2095	/*
2096	* While ptraced, group stop is handled by STOP trap.
2097	* Schedule it and let the caller deal with it.
2098	*/
2099	task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2100	return false;
2101	}
2102	}
2103
2104	/**
2105	* do_jobctl_trap - take care of ptrace jobctl traps
2106	*
2107	* When PT_SEIZED, it's used for both group stop and explicit
2108	* SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2109	* accompanying siginfo. If stopped, lower eight bits of exit_code contain
2110	* the stop signal; otherwise, %SIGTRAP.
2111	*
2112	* When !PT_SEIZED, it's used only for group stop trap with stop signal
2113	* number as exit_code and no siginfo.
2114	*
2115	* CONTEXT:
2116	* Must be called with @current->sighand->siglock held, which may be
2117	* released and re-acquired before returning with intervening sleep.
2118	*/
2119	static void do_jobctl_trap(void)
2120	{
2121	struct signal_struct *signal = current->signal;
2122	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2123
2124	if (current->ptrace & PT_SEIZED) {
2125	if (!signal->group_stop_count &&
2126	!(signal->flags & SIGNAL_STOP_STOPPED))
2127	signr = SIGTRAP;
2128	WARN_ON_ONCE(!signr);
2129	ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2130	CLD_STOPPED);
2131	} else {
2132	WARN_ON_ONCE(!signr);
2133	ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2134	current->exit_code = 0;
2135	}
2136	}
2137
2138	static int ptrace_signal(int signr, siginfo_t *info)
2139	{
2140	ptrace_signal_deliver();
2141	/*
2142	* We do not check sig_kernel_stop(signr) but set this marker
2143	* unconditionally because we do not know whether debugger will
2144	* change signr. This flag has no meaning unless we are going
2145	* to stop after return from ptrace_stop(). In this case it will
2146	* be checked in do_signal_stop(), we should only stop if it was
2147	* not cleared by SIGCONT while we were sleeping. See also the
2148	* comment in dequeue_signal().
2149	*/
2150	current->jobctl |= JOBCTL_STOP_DEQUEUED;
2151	ptrace_stop(signr, CLD_TRAPPED, 0, info);
2152
2153	/* We're back. Did the debugger cancel the sig? */
2154	signr = current->exit_code;
2155	if (signr == 0)
2156	return signr;
2157
2158	current->exit_code = 0;
2159
2160	/*
2161	* Update the siginfo structure if the signal has
2162	* changed. If the debugger wanted something
2163	* specific in the siginfo structure then it should
2164	* have updated *info via PTRACE_SETSIGINFO.
2165	*/
2166	if (signr != info->si_signo) {
2167	info->si_signo = signr;
2168	info->si_errno = 0;
2169	info->si_code = SI_USER;
2170	rcu_read_lock();
2171	info->si_pid = task_pid_vnr(current->parent);
2172	info->si_uid = from_kuid_munged(current_user_ns(),
2173	task_uid(current->parent));
2174	rcu_read_unlock();
2175	}
2176
2177	/* If the (new) signal is now blocked, requeue it. */
2178	if (sigismember(&current->blocked, signr)) {
2179	specific_send_sig_info(signr, info, current);
2180	signr = 0;
2181	}
2182
2183	return signr;
2184	}
2185
2186	int get_signal(struct ksignal *ksig)
2187	{
2188	struct sighand_struct *sighand = current->sighand;
2189	struct signal_struct *signal = current->signal;
2190	int signr;
2191
2192	if (unlikely(current->task_works))
2193	task_work_run();
2194
2195	if (unlikely(uprobe_deny_signal()))
2196	return 0;
2197
2198	/*
2199	* Do this once, we can't return to user-mode if freezing() == T.
2200	* do_signal_stop() and ptrace_stop() do freezable_schedule() and
2201	* thus do not need another check after return.
2202	*/
2203	try_to_freeze();
2204
2205	relock:
2206	spin_lock_irq(&sighand->siglock);
2207	/*
2208	* Every stopped thread goes here after wakeup. Check to see if
2209	* we should notify the parent, prepare_signal(SIGCONT) encodes
2210	* the CLD_ si_code into SIGNAL_CLD_MASK bits.
2211	*/
2212	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2213	int why;
2214
2215	if (signal->flags & SIGNAL_CLD_CONTINUED)
2216	why = CLD_CONTINUED;
2217	else
2218	why = CLD_STOPPED;
2219
2220	signal->flags &= ~SIGNAL_CLD_MASK;
2221
2222	spin_unlock_irq(&sighand->siglock);
2223
2224	/*
2225	* Notify the parent that we're continuing. This event is
2226	* always per-process and doesn't make whole lot of sense
2227	* for ptracers, who shouldn't consume the state via
2228	* wait(2) either, but, for backward compatibility, notify
2229	* the ptracer of the group leader too unless it's gonna be
2230	* a duplicate.
2231	*/
2232	read_lock(&tasklist_lock);
2233	do_notify_parent_cldstop(current, false, why);
2234
2235	if (ptrace_reparented(current->group_leader))
2236	do_notify_parent_cldstop(current->group_leader,
2237	true, why);
2238	read_unlock(&tasklist_lock);
2239
2240	goto relock;
2241	}
2242
2243	/* Has this task already been marked for death? */
2244	if (signal_group_exit(signal)) {
2245	ksig->info.si_signo = signr = SIGKILL;
2246	sigdelset(&current->pending.signal, SIGKILL);
2247	recalc_sigpending();
2248	goto fatal;
2249	}
2250
2251	for (;;) {
2252	struct k_sigaction *ka;
2253
2254	if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2255	do_signal_stop(0))
2256	goto relock;
2257
2258	if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2259	do_jobctl_trap();
2260	spin_unlock_irq(&sighand->siglock);
2261	goto relock;
2262	}
2263
2264	/*
2265	* Signals generated by the execution of an instruction
2266	* need to be delivered before any other pending signals
2267	* so that the instruction pointer in the signal stack
2268	* frame points to the faulting instruction.
2269	*/
2270	signr = dequeue_synchronous_signal(&ksig->info);
2271	if (!signr)
2272	signr = dequeue_signal(current, &current->blocked, &ksig->info);
2273
2274	if (!signr)
2275	break; /* will return 0 */
2276
2277	if (unlikely(current->ptrace) && signr != SIGKILL) {
2278	signr = ptrace_signal(signr, &ksig->info);
2279	if (!signr)
2280	continue;
2281	}
2282
2283	ka = &sighand->action[signr-1];
2284
2285	/* Trace actually delivered signals. */
2286	trace_signal_deliver(signr, &ksig->info, ka);
2287
2288	if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2289	continue;
2290	if (ka->sa.sa_handler != SIG_DFL) {
2291	/* Run the handler. */
2292	ksig->ka = *ka;
2293
2294	if (ka->sa.sa_flags & SA_ONESHOT)
2295	ka->sa.sa_handler = SIG_DFL;
2296
2297	break; /* will return non-zero "signr" value */
2298	}
2299
2300	/*
2301	* Now we are doing the default action for this signal.
2302	*/
2303	if (sig_kernel_ignore(signr)) /* Default is nothing. */
2304	continue;
2305
2306	/*
2307	* Global init gets no signals it doesn't want.
2308	* Container-init gets no signals it doesn't want from same
2309	* container.
2310	*
2311	* Note that if global/container-init sees a sig_kernel_only()
2312	* signal here, the signal must have been generated internally
2313	* or must have come from an ancestor namespace. In either
2314	* case, the signal cannot be dropped.
2315	*/
2316	if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2317	!sig_kernel_only(signr))
2318	continue;
2319
2320	if (sig_kernel_stop(signr)) {
2321	/*
2322	* The default action is to stop all threads in
2323	* the thread group. The job control signals
2324	* do nothing in an orphaned pgrp, but SIGSTOP
2325	* always works. Note that siglock needs to be
2326	* dropped during the call to is_orphaned_pgrp()
2327	* because of lock ordering with tasklist_lock.
2328	* This allows an intervening SIGCONT to be posted.
2329	* We need to check for that and bail out if necessary.
2330	*/
2331	if (signr != SIGSTOP) {
2332	spin_unlock_irq(&sighand->siglock);
2333
2334	/* signals can be posted during this window */
2335
2336	if (is_current_pgrp_orphaned())
2337	goto relock;
2338
2339	spin_lock_irq(&sighand->siglock);
2340	}
2341
2342	if (likely(do_signal_stop(ksig->info.si_signo))) {
2343	/* It released the siglock. */
2344	goto relock;
2345	}
2346
2347	/*
2348	* We didn't actually stop, due to a race
2349	* with SIGCONT or something like that.
2350	*/
2351	continue;
2352	}
2353
2354	fatal:
2355	spin_unlock_irq(&sighand->siglock);
2356
2357	/*
2358	* Anything else is fatal, maybe with a core dump.
2359	*/
2360	current->flags |= PF_SIGNALED;
2361
2362	if (sig_kernel_coredump(signr)) {
2363	if (print_fatal_signals)
2364	print_fatal_signal(ksig->info.si_signo);
2365	proc_coredump_connector(current);
2366	/*
2367	* If it was able to dump core, this kills all
2368	* other threads in the group and synchronizes with
2369	* their demise. If we lost the race with another
2370	* thread getting here, it set group_exit_code
2371	* first and our do_group_exit call below will use
2372	* that value and ignore the one we pass it.
2373	*/
2374	do_coredump(&ksig->info);
2375	}
2376
2377	/*
2378	* Death signals, no core dump.
2379	*/
2380	do_group_exit(ksig->info.si_signo);
2381	/* NOTREACHED */
2382	}
2383	spin_unlock_irq(&sighand->siglock);
2384
2385	ksig->sig = signr;
2386	return ksig->sig > 0;
2387	}
2388
2389	/**
2390	* signal_delivered -
2391	* @ksig: kernel signal struct
2392	* @stepping: nonzero if debugger single-step or block-step in use
2393	*
2394	* This function should be called when a signal has successfully been
2395	* delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2396	* is always blocked, and the signal itself is blocked unless %SA_NODEFER
2397	* is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2398	*/
2399	static void signal_delivered(struct ksignal *ksig, int stepping)
2400	{
2401	sigset_t blocked;
2402
2403	/* A signal was successfully delivered, and the
2404	saved sigmask was stored on the signal frame,
2405	and will be restored by sigreturn. So we can
2406	simply clear the restore sigmask flag. */
2407	clear_restore_sigmask();
2408
2409	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
2410	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2411	sigaddset(&blocked, ksig->sig);
2412	set_current_blocked(&blocked);
2413	tracehook_signal_handler(stepping);
2414	}
2415
2416	void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2417	{
2418	if (failed)
2419	force_sigsegv(ksig->sig, current);
2420	else
2421	signal_delivered(ksig, stepping);
2422	}
2423
2424	/*
2425	* It could be that complete_signal() picked us to notify about the
2426	* group-wide signal. Other threads should be notified now to take
2427	* the shared signals in @which since we will not.
2428	*/
2429	static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2430	{
2431	sigset_t retarget;
2432	struct task_struct *t;
2433
2434	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2435	if (sigisemptyset(&retarget))
2436	return;
2437
2438	t = tsk;
2439	while_each_thread(tsk, t) {
2440	if (t->flags & PF_EXITING)
2441	continue;
2442
2443	if (!has_pending_signals(&retarget, &t->blocked))
2444	continue;
2445	/* Remove the signals this thread can handle. */
2446	sigandsets(&retarget, &retarget, &t->blocked);
2447
2448	if (!signal_pending(t))
2449	signal_wake_up(t, 0);
2450
2451	if (sigisemptyset(&retarget))
2452	break;
2453	}
2454	}
2455
2456	void exit_signals(struct task_struct *tsk)
2457	{
2458	int group_stop = 0;
2459	sigset_t unblocked;
2460
2461	/*
2462	* @tsk is about to have PF_EXITING set - lock out users which
2463	* expect stable threadgroup.
2464	*/
2465	threadgroup_change_begin(tsk);
2466
2467	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2468	tsk->flags |= PF_EXITING;
2469	threadgroup_change_end(tsk);
2470	return;
2471	}
2472
2473	spin_lock_irq(&tsk->sighand->siglock);
2474	/*
2475	* From now this task is not visible for group-wide signals,
2476	* see wants_signal(), do_signal_stop().
2477	*/
2478	tsk->flags |= PF_EXITING;
2479
2480	threadgroup_change_end(tsk);
2481
2482	if (!signal_pending(tsk))
2483	goto out;
2484
2485	unblocked = tsk->blocked;
2486	signotset(&unblocked);
2487	retarget_shared_pending(tsk, &unblocked);
2488
2489	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2490	task_participate_group_stop(tsk))
2491	group_stop = CLD_STOPPED;
2492	out:
2493	spin_unlock_irq(&tsk->sighand->siglock);
2494
2495	/*
2496	* If group stop has completed, deliver the notification. This
2497	* should always go to the real parent of the group leader.
2498	*/
2499	if (unlikely(group_stop)) {
2500	read_lock(&tasklist_lock);
2501	do_notify_parent_cldstop(tsk, false, group_stop);
2502	read_unlock(&tasklist_lock);
2503	}
2504	}
2505
2506	EXPORT_SYMBOL(recalc_sigpending);
2507	EXPORT_SYMBOL_GPL(dequeue_signal);
2508	EXPORT_SYMBOL(flush_signals);
2509	EXPORT_SYMBOL(force_sig);
2510	EXPORT_SYMBOL(send_sig);
2511	EXPORT_SYMBOL(send_sig_info);
2512	EXPORT_SYMBOL(sigprocmask);
2513
2514	/*
2515	* System call entry points.
2516	*/
2517
2518	/**
2519	* sys_restart_syscall - restart a system call
2520	*/
2521	SYSCALL_DEFINE0(restart_syscall)
2522	{
2523	struct restart_block *restart = &current->restart_block;
2524	return restart->fn(restart);
2525	}
2526
2527	long do_no_restart_syscall(struct restart_block *param)
2528	{
2529	return -EINTR;
2530	}
2531
2532	static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2533	{
2534	if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2535	sigset_t newblocked;
2536	/* A set of now blocked but previously unblocked signals. */
2537	sigandnsets(&newblocked, newset, &current->blocked);
2538	retarget_shared_pending(tsk, &newblocked);
2539	}
2540	tsk->blocked = *newset;
2541	recalc_sigpending();
2542	}
2543
2544	/**
2545	* set_current_blocked - change current->blocked mask
2546	* @newset: new mask
2547	*
2548	* It is wrong to change ->blocked directly, this helper should be used
2549	* to ensure the process can't miss a shared signal we are going to block.
2550	*/
2551	void set_current_blocked(sigset_t *newset)
2552	{
2553	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2554	__set_current_blocked(newset);
2555	}
2556
2557	void __set_current_blocked(const sigset_t *newset)
2558	{
2559	struct task_struct *tsk = current;
2560
2561	/*
2562	* In case the signal mask hasn't changed, there is nothing we need
2563	* to do. The current->blocked shouldn't be modified by other task.
2564	*/
2565	if (sigequalsets(&tsk->blocked, newset))
2566	return;
2567
2568	spin_lock_irq(&tsk->sighand->siglock);
2569	__set_task_blocked(tsk, newset);
2570	spin_unlock_irq(&tsk->sighand->siglock);
2571	}
2572
2573	/*
2574	* This is also useful for kernel threads that want to temporarily
2575	* (or permanently) block certain signals.
2576	*
2577	* NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2578	* interface happily blocks "unblockable" signals like SIGKILL
2579	* and friends.
2580	*/
2581	int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2582	{
2583	struct task_struct *tsk = current;
2584	sigset_t newset;
2585
2586	/* Lockless, only current can change ->blocked, never from irq */
2587	if (oldset)
2588	*oldset = tsk->blocked;
2589
2590	switch (how) {
2591	case SIG_BLOCK:
2592	sigorsets(&newset, &tsk->blocked, set);
2593	break;
2594	case SIG_UNBLOCK:
2595	sigandnsets(&newset, &tsk->blocked, set);
2596	break;
2597	case SIG_SETMASK:
2598	newset = *set;
2599	break;
2600	default:
2601	return -EINVAL;
2602	}
2603
2604	__set_current_blocked(&newset);
2605	return 0;
2606	}
2607
2608	/**
2609	* sys_rt_sigprocmask - change the list of currently blocked signals
2610	* @how: whether to add, remove, or set signals
2611	* @nset: stores pending signals
2612	* @oset: previous value of signal mask if non-null
2613	* @sigsetsize: size of sigset_t type
2614	*/
2615	SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2616	sigset_t __user *, oset, size_t, sigsetsize)
2617	{
2618	sigset_t old_set, new_set;
2619	int error;
2620
2621	/* XXX: Don't preclude handling different sized sigset_t's. */
2622	if (sigsetsize != sizeof(sigset_t))
2623	return -EINVAL;
2624
2625	old_set = current->blocked;
2626
2627	if (nset) {
2628	if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2629	return -EFAULT;
2630	sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2631
2632	error = sigprocmask(how, &new_set, NULL);
2633	if (error)
2634	return error;
2635	}
2636
2637	if (oset) {
2638	if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2639	return -EFAULT;
2640	}
2641
2642	return 0;
2643	}
2644
2645	#ifdef CONFIG_COMPAT
2646	COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2647	compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2648	{
2649	#ifdef __BIG_ENDIAN
2650	sigset_t old_set = current->blocked;
2651
2652	/* XXX: Don't preclude handling different sized sigset_t's. */
2653	if (sigsetsize != sizeof(sigset_t))
2654	return -EINVAL;
2655
2656	if (nset) {
2657	compat_sigset_t new32;
2658	sigset_t new_set;
2659	int error;
2660	if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2661	return -EFAULT;
2662
2663	sigset_from_compat(&new_set, &new32);
2664	sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2665
2666	error = sigprocmask(how, &new_set, NULL);
2667	if (error)
2668	return error;
2669	}
2670	if (oset) {
2671	compat_sigset_t old32;
2672	sigset_to_compat(&old32, &old_set);
2673	if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2674	return -EFAULT;
2675	}
2676	return 0;
2677	#else
2678	return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2679	(sigset_t __user *)oset, sigsetsize);
2680	#endif
2681	}
2682	#endif
2683
2684	static int do_sigpending(void *set, unsigned long sigsetsize)
2685	{
2686	if (sigsetsize > sizeof(sigset_t))
2687	return -EINVAL;
2688
2689	spin_lock_irq(&current->sighand->siglock);
2690	sigorsets(set, &current->pending.signal,
2691	&current->signal->shared_pending.signal);
2692	spin_unlock_irq(&current->sighand->siglock);
2693
2694	/* Outside the lock because only this thread touches it. */
2695	sigandsets(set, &current->blocked, set);
2696	return 0;
2697	}
2698
2699	/**
2700	* sys_rt_sigpending - examine a pending signal that has been raised
2701	* while blocked
2702	* @uset: stores pending signals
2703	* @sigsetsize: size of sigset_t type or larger
2704	*/
2705	SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2706	{
2707	sigset_t set;
2708	int err = do_sigpending(&set, sigsetsize);
2709	if (!err && copy_to_user(uset, &set, sigsetsize))
2710	err = -EFAULT;
2711	return err;
2712	}
2713
2714	#ifdef CONFIG_COMPAT
2715	COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2716	compat_size_t, sigsetsize)
2717	{
2718	#ifdef __BIG_ENDIAN
2719	sigset_t set;
2720	int err = do_sigpending(&set, sigsetsize);
2721	if (!err) {
2722	compat_sigset_t set32;
2723	sigset_to_compat(&set32, &set);
2724	/* we can get here only if sigsetsize <= sizeof(set) */
2725	if (copy_to_user(uset, &set32, sigsetsize))
2726	err = -EFAULT;
2727	}
2728	return err;
2729	#else
2730	return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2731	#endif
2732	}
2733	#endif
2734
2735	#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2736
2737	int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2738	{
2739	int err;
2740
2741	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2742	return -EFAULT;
2743	if (from->si_code < 0)
2744	return __copy_to_user(to, from, sizeof(siginfo_t))
2745	? -EFAULT : 0;
2746	/*
2747	* If you change siginfo_t structure, please be sure
2748	* this code is fixed accordingly.
2749	* Please remember to update the signalfd_copyinfo() function
2750	* inside fs/signalfd.c too, in case siginfo_t changes.
2751	* It should never copy any pad contained in the structure
2752	* to avoid security leaks, but must copy the generic
2753	* 3 ints plus the relevant union member.
2754	*/
2755	err = __put_user(from->si_signo, &to->si_signo);
2756	err |= __put_user(from->si_errno, &to->si_errno);
2757	err |= __put_user((short)from->si_code, &to->si_code);
2758	switch (from->si_code & __SI_MASK) {
2759	case __SI_KILL:
2760	err |= __put_user(from->si_pid, &to->si_pid);
2761	err |= __put_user(from->si_uid, &to->si_uid);
2762	break;
2763	case __SI_TIMER:
2764	err |= __put_user(from->si_tid, &to->si_tid);
2765	err |= __put_user(from->si_overrun, &to->si_overrun);
2766	err |= __put_user(from->si_ptr, &to->si_ptr);
2767	break;
2768	case __SI_POLL:
2769	err |= __put_user(from->si_band, &to->si_band);
2770	err |= __put_user(from->si_fd, &to->si_fd);
2771	break;
2772	case __SI_FAULT:
2773	err |= __put_user(from->si_addr, &to->si_addr);
2774	#ifdef __ARCH_SI_TRAPNO
2775	err |= __put_user(from->si_trapno, &to->si_trapno);
2776	#endif
2777	#ifdef BUS_MCEERR_AO
2778	/*
2779	* Other callers might not initialize the si_lsb field,
2780	* so check explicitly for the right codes here.
2781	*/
2782	if (from->si_signo == SIGBUS &&
2783	(from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
2784	err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2785	#endif
2786	#ifdef SEGV_BNDERR
2787	if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2788	err |= __put_user(from->si_lower, &to->si_lower);
2789	err |= __put_user(from->si_upper, &to->si_upper);
2790	}
2791	#endif
2792	#ifdef SEGV_PKUERR
2793	if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2794	err |= __put_user(from->si_pkey, &to->si_pkey);
2795	#endif
2796	break;
2797	case __SI_CHLD:
2798	err |= __put_user(from->si_pid, &to->si_pid);
2799	err |= __put_user(from->si_uid, &to->si_uid);
2800	err |= __put_user(from->si_status, &to->si_status);
2801	err |= __put_user(from->si_utime, &to->si_utime);
2802	err |= __put_user(from->si_stime, &to->si_stime);
2803	break;
2804	case __SI_RT: /* This is not generated by the kernel as of now. */
2805	case __SI_MESGQ: /* But this is */
2806	err |= __put_user(from->si_pid, &to->si_pid);
2807	err |= __put_user(from->si_uid, &to->si_uid);
2808	err |= __put_user(from->si_ptr, &to->si_ptr);
2809	break;
2810	#ifdef __ARCH_SIGSYS
2811	case __SI_SYS:
2812	err |= __put_user(from->si_call_addr, &to->si_call_addr);
2813	err |= __put_user(from->si_syscall, &to->si_syscall);
2814	err |= __put_user(from->si_arch, &to->si_arch);
2815	break;
2816	#endif
2817	default: /* this is just in case for now ... */
2818	err |= __put_user(from->si_pid, &to->si_pid);
2819	err |= __put_user(from->si_uid, &to->si_uid);
2820	break;
2821	}
2822	return err;
2823	}
2824
2825	#endif
2826
2827	/**
2828	* do_sigtimedwait - wait for queued signals specified in @which
2829	* @which: queued signals to wait for
2830	* @info: if non-null, the signal's siginfo is returned here
2831	* @ts: upper bound on process time suspension
2832	*/
2833	int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2834	const struct timespec *ts)
2835	{
2836	ktime_t *to = NULL, timeout = { .tv64 = KTIME_MAX };
2837	struct task_struct *tsk = current;
2838	sigset_t mask = *which;
2839	int sig, ret = 0;
2840
2841	if (ts) {
2842	if (!timespec_valid(ts))
2843	return -EINVAL;
2844	timeout = timespec_to_ktime(*ts);
2845	to = &timeout;
2846	}
2847
2848	/*
2849	* Invert the set of allowed signals to get those we want to block.
2850	*/
2851	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2852	signotset(&mask);
2853
2854	spin_lock_irq(&tsk->sighand->siglock);
2855	sig = dequeue_signal(tsk, &mask, info);
2856	if (!sig && timeout.tv64) {
2857	/*
2858	* None ready, temporarily unblock those we're interested
2859	* while we are sleeping in so that we'll be awakened when
2860	* they arrive. Unblocking is always fine, we can avoid
2861	* set_current_blocked().
2862	*/
2863	tsk->real_blocked = tsk->blocked;
2864	sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2865	recalc_sigpending();
2866	spin_unlock_irq(&tsk->sighand->siglock);
2867
2868	__set_current_state(TASK_INTERRUPTIBLE);
2869	ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
2870	HRTIMER_MODE_REL);
2871	spin_lock_irq(&tsk->sighand->siglock);
2872	__set_task_blocked(tsk, &tsk->real_blocked);
2873	sigemptyset(&tsk->real_blocked);
2874	sig = dequeue_signal(tsk, &mask, info);
2875	}
2876	spin_unlock_irq(&tsk->sighand->siglock);
2877
2878	if (sig)
2879	return sig;
2880	return ret ? -EINTR : -EAGAIN;
2881	}
2882
2883	/**
2884	* sys_rt_sigtimedwait - synchronously wait for queued signals specified
2885	* in @uthese
2886	* @uthese: queued signals to wait for
2887	* @uinfo: if non-null, the signal's siginfo is returned here
2888	* @uts: upper bound on process time suspension
2889	* @sigsetsize: size of sigset_t type
2890	*/
2891	SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2892	siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2893	size_t, sigsetsize)
2894	{
2895	sigset_t these;
2896	struct timespec ts;
2897	siginfo_t info;
2898	int ret;
2899
2900	/* XXX: Don't preclude handling different sized sigset_t's. */
2901	if (sigsetsize != sizeof(sigset_t))
2902	return -EINVAL;
2903
2904	if (copy_from_user(&these, uthese, sizeof(these)))
2905	return -EFAULT;
2906
2907	if (uts) {
2908	if (copy_from_user(&ts, uts, sizeof(ts)))
2909	return -EFAULT;
2910	}
2911
2912	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2913
2914	if (ret > 0 && uinfo) {
2915	if (copy_siginfo_to_user(uinfo, &info))
2916	ret = -EFAULT;
2917	}
2918
2919	return ret;
2920	}
2921
2922	/**
2923	* sys_kill - send a signal to a process
2924	* @pid: the PID of the process
2925	* @sig: signal to be sent
2926	*/
2927	SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2928	{
2929	struct siginfo info;
2930
2931	info.si_signo = sig;
2932	info.si_errno = 0;
2933	info.si_code = SI_USER;
2934	info.si_pid = task_tgid_vnr(current);
2935	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2936
2937	return kill_something_info(sig, &info, pid);
2938	}
2939
2940	static int
2941	do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2942	{
2943	struct task_struct *p;
2944	int error = -ESRCH;
2945
2946	rcu_read_lock();
2947	p = find_task_by_vpid(pid);
2948	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2949	error = check_kill_permission(sig, info, p);
2950	/*
2951	* The null signal is a permissions and process existence
2952	* probe. No signal is actually delivered.
2953	*/
2954	if (!error && sig) {
2955	error = do_send_sig_info(sig, info, p, false);
2956	/*
2957	* If lock_task_sighand() failed we pretend the task
2958	* dies after receiving the signal. The window is tiny,
2959	* and the signal is private anyway.
2960	*/
2961	if (unlikely(error == -ESRCH))
2962	error = 0;
2963	}
2964	}
2965	rcu_read_unlock();
2966
2967	return error;
2968	}
2969
2970	static int do_tkill(pid_t tgid, pid_t pid, int sig)
2971	{
2972	struct siginfo info = {};
2973
2974	info.si_signo = sig;
2975	info.si_errno = 0;
2976	info.si_code = SI_TKILL;
2977	info.si_pid = task_tgid_vnr(current);
2978	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2979
2980	return do_send_specific(tgid, pid, sig, &info);
2981	}
2982
2983	/**
2984	* sys_tgkill - send signal to one specific thread
2985	* @tgid: the thread group ID of the thread
2986	* @pid: the PID of the thread
2987	* @sig: signal to be sent
2988	*
2989	* This syscall also checks the @tgid and returns -ESRCH even if the PID
2990	* exists but it's not belonging to the target process anymore. This
2991	* method solves the problem of threads exiting and PIDs getting reused.
2992	*/
2993	SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2994	{
2995	/* This is only valid for single tasks */
2996	if (pid <= 0 || tgid <= 0)
2997	return -EINVAL;
2998
2999	return do_tkill(tgid, pid, sig);
3000	}
3001
3002	/**
3003	* sys_tkill - send signal to one specific task
3004	* @pid: the PID of the task
3005	* @sig: signal to be sent
3006	*
3007	* Send a signal to only one task, even if it's a CLONE_THREAD task.
3008	*/
3009	SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3010	{
3011	/* This is only valid for single tasks */
3012	if (pid <= 0)
3013	return -EINVAL;
3014
3015	return do_tkill(0, pid, sig);
3016	}
3017
3018	static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3019	{
3020	/* Not even root can pretend to send signals from the kernel.
3021	* Nor can they impersonate a kill()/tgkill(), which adds source info.
3022	*/
3023	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3024	(task_pid_vnr(current) != pid))
3025	return -EPERM;
3026
3027	info->si_signo = sig;
3028
3029	/* POSIX.1b doesn't mention process groups. */
3030	return kill_proc_info(sig, info, pid);
3031	}
3032
3033	/**
3034	* sys_rt_sigqueueinfo - send signal information to a signal
3035	* @pid: the PID of the thread
3036	* @sig: signal to be sent
3037	* @uinfo: signal info to be sent
3038	*/
3039	SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3040	siginfo_t __user *, uinfo)
3041	{
3042	siginfo_t info;
3043	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3044	return -EFAULT;
3045	return do_rt_sigqueueinfo(pid, sig, &info);
3046	}
3047
3048	#ifdef CONFIG_COMPAT
3049	COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3050	compat_pid_t, pid,
3051	int, sig,
3052	struct compat_siginfo __user *, uinfo)
3053	{
3054	siginfo_t info = {};
3055	int ret = copy_siginfo_from_user32(&info, uinfo);
3056	if (unlikely(ret))
3057	return ret;
3058	return do_rt_sigqueueinfo(pid, sig, &info);
3059	}
3060	#endif
3061
3062	static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3063	{
3064	/* This is only valid for single tasks */
3065	if (pid <= 0 || tgid <= 0)
3066	return -EINVAL;
3067
3068	/* Not even root can pretend to send signals from the kernel.
3069	* Nor can they impersonate a kill()/tgkill(), which adds source info.
3070	*/
3071	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3072	(task_pid_vnr(current) != pid))
3073	return -EPERM;
3074
3075	info->si_signo = sig;
3076
3077	return do_send_specific(tgid, pid, sig, info);
3078	}
3079
3080	SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3081	siginfo_t __user *, uinfo)
3082	{
3083	siginfo_t info;
3084
3085	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3086	return -EFAULT;
3087
3088	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3089	}
3090
3091	#ifdef CONFIG_COMPAT
3092	COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3093	compat_pid_t, tgid,
3094	compat_pid_t, pid,
3095	int, sig,
3096	struct compat_siginfo __user *, uinfo)
3097	{
3098	siginfo_t info = {};
3099
3100	if (copy_siginfo_from_user32(&info, uinfo))
3101	return -EFAULT;
3102	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3103	}
3104	#endif
3105
3106	/*
3107	* For kthreads only, must not be used if cloned with CLONE_SIGHAND
3108	*/
3109	void kernel_sigaction(int sig, __sighandler_t action)
3110	{
3111	spin_lock_irq(&current->sighand->siglock);
3112	current->sighand->action[sig - 1].sa.sa_handler = action;
3113	if (action == SIG_IGN) {
3114	sigset_t mask;
3115
3116	sigemptyset(&mask);
3117	sigaddset(&mask, sig);
3118
3119	flush_sigqueue_mask(&mask, &current->signal->shared_pending);
3120	flush_sigqueue_mask(&mask, &current->pending);
3121	recalc_sigpending();
3122	}
3123	spin_unlock_irq(&current->sighand->siglock);
3124	}
3125	EXPORT_SYMBOL(kernel_sigaction);
3126
3127	void __weak sigaction_compat_abi(struct k_sigaction *act,
3128	struct k_sigaction *oact)
3129	{
3130	}
3131
3132	int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3133	{
3134	struct task_struct *p = current, *t;
3135	struct k_sigaction *k;
3136	sigset_t mask;
3137
3138	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3139	return -EINVAL;
3140
3141	k = &p->sighand->action[sig-1];
3142
3143	spin_lock_irq(&p->sighand->siglock);
3144	if (oact)
3145	*oact = *k;
3146
3147	sigaction_compat_abi(act, oact);
3148
3149	if (act) {
3150	sigdelsetmask(&act->sa.sa_mask,
3151	sigmask(SIGKILL) | sigmask(SIGSTOP));
3152	*k = *act;
3153	/*
3154	* POSIX 3.3.1.3:
3155	* "Setting a signal action to SIG_IGN for a signal that is
3156	* pending shall cause the pending signal to be discarded,
3157	* whether or not it is blocked."
3158	*
3159	* "Setting a signal action to SIG_DFL for a signal that is
3160	* pending and whose default action is to ignore the signal
3161	* (for example, SIGCHLD), shall cause the pending signal to
3162	* be discarded, whether or not it is blocked"
3163	*/
3164	if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3165	sigemptyset(&mask);
3166	sigaddset(&mask, sig);
3167	flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3168	for_each_thread(p, t)
3169	flush_sigqueue_mask(&mask, &t->pending);
3170	}
3171	}
3172
3173	spin_unlock_irq(&p->sighand->siglock);
3174	return 0;
3175	}
3176
3177	static int
3178	do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp,
3179	size_t min_ss_size)
3180	{
3181	stack_t oss;
3182	int error;
3183
3184	oss.ss_sp = (void __user *) current->sas_ss_sp;
3185	oss.ss_size = current->sas_ss_size;
3186	oss.ss_flags = sas_ss_flags(sp) |
3187	(current->sas_ss_flags & SS_FLAG_BITS);
3188
3189	if (uss) {
3190	void __user *ss_sp;
3191	size_t ss_size;
3192	unsigned ss_flags;
3193	int ss_mode;
3194
3195	error = -EFAULT;
3196	if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3197	goto out;
3198	error = __get_user(ss_sp, &uss->ss_sp) |
3199	__get_user(ss_flags, &uss->ss_flags) |
3200	__get_user(ss_size, &uss->ss_size);
3201	if (error)
3202	goto out;
3203
3204	error = -EPERM;
3205	if (on_sig_stack(sp))
3206	goto out;
3207
3208	ss_mode = ss_flags & ~SS_FLAG_BITS;
3209	error = -EINVAL;
3210	if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3211	ss_mode != 0)
3212	goto out;
3213
3214	if (ss_mode == SS_DISABLE) {
3215	ss_size = 0;
3216	ss_sp = NULL;
3217	} else {
3218	if (unlikely(ss_size < min_ss_size))
3219	return -ENOMEM;
3220	}
3221
3222	current->sas_ss_sp = (unsigned long) ss_sp;
3223	current->sas_ss_size = ss_size;
3224	current->sas_ss_flags = ss_flags;
3225	}
3226
3227	error = 0;
3228	if (uoss) {
3229	error = -EFAULT;
3230	if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3231	goto out;
3232	error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3233	__put_user(oss.ss_size, &uoss->ss_size) |
3234	__put_user(oss.ss_flags, &uoss->ss_flags);
3235	}
3236
3237	out:
3238	return error;
3239	}
3240	SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3241	{
3242	return do_sigaltstack(uss, uoss, current_user_stack_pointer(),
3243	MINSIGSTKSZ);
3244	}
3245
3246	int restore_altstack(const stack_t __user *uss)
3247	{
3248	int err = do_sigaltstack(uss, NULL, current_user_stack_pointer(),
3249	MINSIGSTKSZ);
3250	/* squash all but EFAULT for now */
3251	return err == -EFAULT ? err : 0;
3252	}
3253
3254	int __save_altstack(stack_t __user *uss, unsigned long sp)
3255	{
3256	struct task_struct *t = current;
3257	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3258	__put_user(t->sas_ss_flags, &uss->ss_flags) |
3259	__put_user(t->sas_ss_size, &uss->ss_size);
3260	if (err)
3261	return err;
3262	if (t->sas_ss_flags & SS_AUTODISARM)
3263	sas_ss_reset(t);
3264	return 0;
3265	}
3266
3267	#ifdef CONFIG_COMPAT
3268	COMPAT_SYSCALL_DEFINE2(sigaltstack,
3269	const compat_stack_t __user *, uss_ptr,
3270	compat_stack_t __user *, uoss_ptr)
3271	{
3272	stack_t uss, uoss;
3273	int ret;
3274	mm_segment_t seg;
3275
3276	if (uss_ptr) {
3277	compat_stack_t uss32;
3278
3279	memset(&uss, 0, sizeof(stack_t));
3280	if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3281	return -EFAULT;
3282	uss.ss_sp = compat_ptr(uss32.ss_sp);
3283	uss.ss_flags = uss32.ss_flags;
3284	uss.ss_size = uss32.ss_size;
3285	}
3286	seg = get_fs();
3287	set_fs(KERNEL_DS);
3288	ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3289	(stack_t __force __user *) &uoss,
3290	compat_user_stack_pointer(),
3291	COMPAT_MINSIGSTKSZ);
3292	set_fs(seg);
3293	if (ret >= 0 && uoss_ptr) {
3294	if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3295	__put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3296	__put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3297	__put_user(uoss.ss_size, &uoss_ptr->ss_size))
3298	ret = -EFAULT;
3299	}
3300	return ret;
3301	}
3302
3303	int compat_restore_altstack(const compat_stack_t __user *uss)
3304	{
3305	int err = compat_sys_sigaltstack(uss, NULL);
3306	/* squash all but -EFAULT for now */
3307	return err == -EFAULT ? err : 0;
3308	}
3309
3310	int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3311	{
3312	int err;
3313	struct task_struct *t = current;
3314	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3315	&uss->ss_sp) |
3316	__put_user(t->sas_ss_flags, &uss->ss_flags) |
3317	__put_user(t->sas_ss_size, &uss->ss_size);
3318	if (err)
3319	return err;
3320	if (t->sas_ss_flags & SS_AUTODISARM)
3321	sas_ss_reset(t);
3322	return 0;
3323	}
3324	#endif
3325
3326	#ifdef __ARCH_WANT_SYS_SIGPENDING
3327
3328	/**
3329	* sys_sigpending - examine pending signals
3330	* @set: where mask of pending signal is returned
3331	*/
3332	SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3333	{
3334	return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t));
3335	}
3336
3337	#endif
3338
3339	#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3340	/**
3341	* sys_sigprocmask - examine and change blocked signals
3342	* @how: whether to add, remove, or set signals
3343	* @nset: signals to add or remove (if non-null)
3344	* @oset: previous value of signal mask if non-null
3345	*
3346	* Some platforms have their own version with special arguments;
3347	* others support only sys_rt_sigprocmask.
3348	*/
3349
3350	SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3351	old_sigset_t __user *, oset)
3352	{
3353	old_sigset_t old_set, new_set;
3354	sigset_t new_blocked;
3355
3356	old_set = current->blocked.sig[0];
3357
3358	if (nset) {
3359	if (copy_from_user(&new_set, nset, sizeof(*nset)))
3360	return -EFAULT;
3361
3362	new_blocked = current->blocked;
3363
3364	switch (how) {
3365	case SIG_BLOCK:
3366	sigaddsetmask(&new_blocked, new_set);
3367	break;
3368	case SIG_UNBLOCK:
3369	sigdelsetmask(&new_blocked, new_set);
3370	break;
3371	case SIG_SETMASK:
3372	new_blocked.sig[0] = new_set;
3373	break;
3374	default:
3375	return -EINVAL;
3376	}
3377
3378	set_current_blocked(&new_blocked);
3379	}
3380
3381	if (oset) {
3382	if (copy_to_user(oset, &old_set, sizeof(*oset)))
3383	return -EFAULT;
3384	}
3385
3386	return 0;
3387	}
3388	#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3389
3390	#ifndef CONFIG_ODD_RT_SIGACTION
3391	/**
3392	* sys_rt_sigaction - alter an action taken by a process
3393	* @sig: signal to be sent
3394	* @act: new sigaction
3395	* @oact: used to save the previous sigaction
3396	* @sigsetsize: size of sigset_t type
3397	*/
3398	SYSCALL_DEFINE4(rt_sigaction, int, sig,
3399	const struct sigaction __user *, act,
3400	struct sigaction __user *, oact,
3401	size_t, sigsetsize)
3402	{
3403	struct k_sigaction new_sa, old_sa;
3404	int ret = -EINVAL;
3405
3406	/* XXX: Don't preclude handling different sized sigset_t's. */
3407	if (sigsetsize != sizeof(sigset_t))
3408	goto out;
3409
3410	if (act) {
3411	if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3412	return -EFAULT;
3413	}
3414
3415	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3416
3417	if (!ret && oact) {
3418	if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3419	return -EFAULT;
3420	}
3421	out:
3422	return ret;
3423	}
3424	#ifdef CONFIG_COMPAT
3425	COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3426	const struct compat_sigaction __user *, act,
3427	struct compat_sigaction __user *, oact,
3428	compat_size_t, sigsetsize)
3429	{
3430	struct k_sigaction new_ka, old_ka;
3431	compat_sigset_t mask;
3432	#ifdef __ARCH_HAS_SA_RESTORER
3433	compat_uptr_t restorer;
3434	#endif
3435	int ret;
3436
3437	/* XXX: Don't preclude handling different sized sigset_t's. */
3438	if (sigsetsize != sizeof(compat_sigset_t))
3439	return -EINVAL;
3440
3441	if (act) {
3442	compat_uptr_t handler;
3443	ret = get_user(handler, &act->sa_handler);
3444	new_ka.sa.sa_handler = compat_ptr(handler);
3445	#ifdef __ARCH_HAS_SA_RESTORER
3446	ret |= get_user(restorer, &act->sa_restorer);
3447	new_ka.sa.sa_restorer = compat_ptr(restorer);
3448	#endif
3449	ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3450	ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3451	if (ret)
3452	return -EFAULT;
3453	sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3454	}
3455
3456	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3457	if (!ret && oact) {
3458	sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3459	ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
3460	&oact->sa_handler);
3461	ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3462	ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3463	#ifdef __ARCH_HAS_SA_RESTORER
3464	ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3465	&oact->sa_restorer);
3466	#endif
3467	}
3468	return ret;
3469	}
3470	#endif
3471	#endif /* !CONFIG_ODD_RT_SIGACTION */
3472
3473	#ifdef CONFIG_OLD_SIGACTION
3474	SYSCALL_DEFINE3(sigaction, int, sig,
3475	const struct old_sigaction __user *, act,
3476	struct old_sigaction __user *, oact)
3477	{
3478	struct k_sigaction new_ka, old_ka;
3479	int ret;
3480
3481	if (act) {
3482	old_sigset_t mask;
3483	if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3484	__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3485	__get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3486	__get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3487	__get_user(mask, &act->sa_mask))
3488	return -EFAULT;
3489	#ifdef __ARCH_HAS_KA_RESTORER
3490	new_ka.ka_restorer = NULL;
3491	#endif
3492	siginitset(&new_ka.sa.sa_mask, mask);
3493	}
3494
3495	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3496
3497	if (!ret && oact) {
3498	if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3499	__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3500	__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3501	__put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3502	__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3503	return -EFAULT;
3504	}
3505
3506	return ret;
3507	}
3508	#endif
3509	#ifdef CONFIG_COMPAT_OLD_SIGACTION
3510	COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3511	const struct compat_old_sigaction __user *, act,
3512	struct compat_old_sigaction __user *, oact)
3513	{
3514	struct k_sigaction new_ka, old_ka;
3515	int ret;
3516	compat_old_sigset_t mask;
3517	compat_uptr_t handler, restorer;
3518
3519	if (act) {
3520	if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3521	__get_user(handler, &act->sa_handler) ||
3522	__get_user(restorer, &act->sa_restorer) ||
3523	__get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3524	__get_user(mask, &act->sa_mask))
3525	return -EFAULT;
3526
3527	#ifdef __ARCH_HAS_KA_RESTORER
3528	new_ka.ka_restorer = NULL;
3529	#endif
3530	new_ka.sa.sa_handler = compat_ptr(handler);
3531	new_ka.sa.sa_restorer = compat_ptr(restorer);
3532	siginitset(&new_ka.sa.sa_mask, mask);
3533	}
3534
3535	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3536
3537	if (!ret && oact) {
3538	if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3539	__put_user(ptr_to_compat(old_ka.sa.sa_handler),
3540	&oact->sa_handler) ||
3541	__put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3542	&oact->sa_restorer) ||
3543	__put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3544	__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3545	return -EFAULT;
3546	}
3547	return ret;
3548	}
3549	#endif
3550
3551	#ifdef CONFIG_SGETMASK_SYSCALL
3552
3553	/*
3554	* For backwards compatibility. Functionality superseded by sigprocmask.
3555	*/
3556	SYSCALL_DEFINE0(sgetmask)
3557	{
3558	/* SMP safe */
3559	return current->blocked.sig[0];
3560	}
3561
3562	SYSCALL_DEFINE1(ssetmask, int, newmask)
3563	{
3564	int old = current->blocked.sig[0];
3565	sigset_t newset;
3566
3567	siginitset(&newset, newmask);
3568	set_current_blocked(&newset);
3569
3570	return old;
3571	}
3572	#endif /* CONFIG_SGETMASK_SYSCALL */
3573
3574	#ifdef __ARCH_WANT_SYS_SIGNAL
3575	/*
3576	* For backwards compatibility. Functionality superseded by sigaction.
3577	*/
3578	SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3579	{
3580	struct k_sigaction new_sa, old_sa;
3581	int ret;
3582
3583	new_sa.sa.sa_handler = handler;
3584	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3585	sigemptyset(&new_sa.sa.sa_mask);
3586
3587	ret = do_sigaction(sig, &new_sa, &old_sa);
3588
3589	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3590	}
3591	#endif /* __ARCH_WANT_SYS_SIGNAL */
3592
3593	#ifdef __ARCH_WANT_SYS_PAUSE
3594
3595	SYSCALL_DEFINE0(pause)
3596	{
3597	while (!signal_pending(current)) {
3598	__set_current_state(TASK_INTERRUPTIBLE);
3599	schedule();
3600	}
3601	return -ERESTARTNOHAND;
3602	}
3603
3604	#endif
3605
3606	static int sigsuspend(sigset_t *set)
3607	{
3608	current->saved_sigmask = current->blocked;
3609	set_current_blocked(set);
3610
3611	while (!signal_pending(current)) {
3612	__set_current_state(TASK_INTERRUPTIBLE);
3613	schedule();
3614	}
3615	set_restore_sigmask();
3616	return -ERESTARTNOHAND;
3617	}
3618
3619	/**
3620	* sys_rt_sigsuspend - replace the signal mask for a value with the
3621	* @unewset value until a signal is received
3622	* @unewset: new signal mask value
3623	* @sigsetsize: size of sigset_t type
3624	*/
3625	SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3626	{
3627	sigset_t newset;
3628
3629	/* XXX: Don't preclude handling different sized sigset_t's. */
3630	if (sigsetsize != sizeof(sigset_t))
3631	return -EINVAL;
3632
3633	if (copy_from_user(&newset, unewset, sizeof(newset)))
3634	return -EFAULT;
3635	return sigsuspend(&newset);
3636	}
3637
3638	#ifdef CONFIG_COMPAT
3639	COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3640	{
3641	#ifdef __BIG_ENDIAN
3642	sigset_t newset;
3643	compat_sigset_t newset32;
3644
3645	/* XXX: Don't preclude handling different sized sigset_t's. */
3646	if (sigsetsize != sizeof(sigset_t))
3647	return -EINVAL;
3648
3649	if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3650	return -EFAULT;
3651	sigset_from_compat(&newset, &newset32);
3652	return sigsuspend(&newset);
3653	#else
3654	/* on little-endian bitmaps don't care about granularity */
3655	return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3656	#endif
3657	}
3658	#endif
3659
3660	#ifdef CONFIG_OLD_SIGSUSPEND
3661	SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3662	{
3663	sigset_t blocked;
3664	siginitset(&blocked, mask);
3665	return sigsuspend(&blocked);
3666	}
3667	#endif
3668	#ifdef CONFIG_OLD_SIGSUSPEND3
3669	SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3670	{
3671	sigset_t blocked;
3672	siginitset(&blocked, mask);
3673	return sigsuspend(&blocked);
3674	}
3675	#endif
3676
3677	__weak const char *arch_vma_name(struct vm_area_struct *vma)
3678	{
3679	return NULL;
3680	}
3681
3682	void __init signals_init(void)
3683	{
3684	/* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
3685	BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
3686	!= offsetof(struct siginfo, _sifields._pad));
3687
3688	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3689	}
3690
3691	#ifdef CONFIG_KGDB_KDB
3692	#include <linux/kdb.h>
3693	/*
3694	* kdb_send_sig_info - Allows kdb to send signals without exposing
3695	* signal internals. This function checks if the required locks are
3696	* available before calling the main signal code, to avoid kdb
3697	* deadlocks.
3698	*/
3699	void
3700	kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3701	{
3702	static struct task_struct *kdb_prev_t;
3703	int sig, new_t;
3704	if (!spin_trylock(&t->sighand->siglock)) {
3705	kdb_printf("Can't do kill command now.\n"
3706	"The sigmask lock is held somewhere else in "
3707	"kernel, try again later\n");
3708	return;
3709	}
3710	spin_unlock(&t->sighand->siglock);
3711	new_t = kdb_prev_t != t;
3712	kdb_prev_t = t;
3713	if (t->state != TASK_RUNNING && new_t) {
3714	kdb_printf("Process is not RUNNING, sending a signal from "
3715	"kdb risks deadlock\n"
3716	"on the run queue locks. "
3717	"The signal has _not_ been sent.\n"
3718	"Reissue the kill command if you want to risk "
3719	"the deadlock.\n");
3720	return;
3721	}
3722	sig = info->si_signo;
3723	if (send_sig_info(sig, info, t))
3724	kdb_printf("Fail to deliver Signal %d to process %d.\n",
3725	sig, t->pid);
3726	else
3727	kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3728	}
3729	#endif /* CONFIG_KGDB_KDB */
3730