1	// SPDX-License-Identifier: GPL-2.0-only
2	/*
3	* linux/kernel/signal.c
4	*
5	* Copyright (C) 1991, 1992 Linus Torvalds
6	*
7	* 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8	*
9	* 2003-06-02 Jim Houston - Concurrent Computer Corp.
10	* Changes to use preallocated sigqueue structures
11	* to allow signals to be sent reliably.
12	*/
13
14	#include <linux/slab.h>
15	#include <linux/export.h>
16	#include <linux/init.h>
17	#include <linux/sched/mm.h>
18	#include <linux/sched/user.h>
19	#include <linux/sched/debug.h>
20	#include <linux/sched/task.h>
21	#include <linux/sched/task_stack.h>
22	#include <linux/sched/cputime.h>
23	#include <linux/file.h>
24	#include <linux/fs.h>
25	#include <linux/mm.h>
26	#include <linux/proc_fs.h>
27	#include <linux/tty.h>
28	#include <linux/binfmts.h>
29	#include <linux/coredump.h>
30	#include <linux/security.h>
31	#include <linux/syscalls.h>
32	#include <linux/ptrace.h>
33	#include <linux/signal.h>
34	#include <linux/signalfd.h>
35	#include <linux/ratelimit.h>
36	#include <linux/task_work.h>
37	#include <linux/capability.h>
38	#include <linux/freezer.h>
39	#include <linux/pid_namespace.h>
40	#include <linux/nsproxy.h>
41	#include <linux/user_namespace.h>
42	#include <linux/uprobes.h>
43	#include <linux/compat.h>
44	#include <linux/cn_proc.h>
45	#include <linux/compiler.h>
46	#include <linux/posix-timers.h>
47	#include <linux/cgroup.h>
48	#include <linux/audit.h>
49	#include <linux/sysctl.h>
50	#include <uapi/linux/pidfd.h>
51
52	#define CREATE_TRACE_POINTS
53	#include <trace/events/signal.h>
54
55	#include <asm/param.h>
56	#include <linux/uaccess.h>
57	#include <asm/unistd.h>
58	#include <asm/siginfo.h>
59	#include <asm/cacheflush.h>
60	#include <asm/syscall.h> /* for syscall_get_* */
61
62	/*
63	* SLAB caches for signal bits.
64	*/
65
66	static struct kmem_cache *sigqueue_cachep;
67
68	int print_fatal_signals __read_mostly;
69
70	static void __user *sig_handler(struct task_struct *t, int sig)
71	{
72	return t->sighand->action[sig - 1].sa.sa_handler;
73	}
74
75	static inline bool sig_handler_ignored(void __user *handler, int sig)
76	{
77	/* Is it explicitly or implicitly ignored? */
78	return handler == SIG_IGN ||
79	(handler == SIG_DFL && sig_kernel_ignore(sig));
80	}
81
82	static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
83	{
84	void __user *handler;
85
86	handler = sig_handler(t, sig);
87
88	/* SIGKILL and SIGSTOP may not be sent to the global init */
89	if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
90	return true;
91
92	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
93	handler == SIG_DFL && !(force && sig_kernel_only(sig)))
94	return true;
95
96	/* Only allow kernel generated signals to this kthread */
97	if (unlikely((t->flags & PF_KTHREAD) &&
98	(handler == SIG_KTHREAD_KERNEL) && !force))
99	return true;
100
101	return sig_handler_ignored(handler, sig);
102	}
103
104	static bool sig_ignored(struct task_struct *t, int sig, bool force)
105	{
106	/*
107	* Blocked signals are never ignored, since the
108	* signal handler may change by the time it is
109	* unblocked.
110	*/
111	if (sigismember(set: &t->blocked, sig: sig) || sigismember(set: &t->real_blocked, sig: sig))
112	return false;
113
114	/*
115	* Tracers may want to know about even ignored signal unless it
116	* is SIGKILL which can't be reported anyway but can be ignored
117	* by SIGNAL_UNKILLABLE task.
118	*/
119	if (t->ptrace && sig != SIGKILL)
120	return false;
121
122	return sig_task_ignored(t, sig, force);
123	}
124
125	/*
126	* Re-calculate pending state from the set of locally pending
127	* signals, globally pending signals, and blocked signals.
128	*/
129	static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
130	{
131	unsigned long ready;
132	long i;
133
134	switch (_NSIG_WORDS) {
135	default:
136	for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
137	ready |= signal->sig[i] &~ blocked->sig[i];
138	break;
139
140	case 4: ready = signal->sig[3] &~ blocked->sig[3];
141	ready |= signal->sig[2] &~ blocked->sig[2];
142	ready |= signal->sig[1] &~ blocked->sig[1];
143	ready |= signal->sig[0] &~ blocked->sig[0];
144	break;
145
146	case 2: ready = signal->sig[1] &~ blocked->sig[1];
147	ready |= signal->sig[0] &~ blocked->sig[0];
148	break;
149
150	case 1: ready = signal->sig[0] &~ blocked->sig[0];
151	}
152	return ready != 0;
153	}
154
155	#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
156
157	static bool recalc_sigpending_tsk(struct task_struct *t)
158	{
159	if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
160	PENDING(&t->pending, &t->blocked) ||
161	PENDING(&t->signal->shared_pending, &t->blocked) ||
162	cgroup_task_frozen(task: t)) {
163	set_tsk_thread_flag(tsk: t, TIF_SIGPENDING);
164	return true;
165	}
166
167	/*
168	* We must never clear the flag in another thread, or in current
169	* when it's possible the current syscall is returning -ERESTART*.
170	* So we don't clear it here, and only callers who know they should do.
171	*/
172	return false;
173	}
174
175	void recalc_sigpending(void)
176	{
177	if (!recalc_sigpending_tsk(current) && !freezing(current))
178	clear_thread_flag(TIF_SIGPENDING);
179
180	}
181	EXPORT_SYMBOL(recalc_sigpending);
182
183	void calculate_sigpending(void)
184	{
185	/* Have any signals or users of TIF_SIGPENDING been delayed
186	* until after fork?
187	*/
188	spin_lock_irq(lock: &current->sighand->siglock);
189	set_tsk_thread_flag(current, TIF_SIGPENDING);
190	recalc_sigpending();
191	spin_unlock_irq(lock: &current->sighand->siglock);
192	}
193
194	/* Given the mask, find the first available signal that should be serviced. */
195
196	#define SYNCHRONOUS_MASK \
197	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
198	sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
199
200	int next_signal(struct sigpending *pending, sigset_t *mask)
201	{
202	unsigned long i, *s, *m, x;
203	int sig = 0;
204
205	s = pending->signal.sig;
206	m = mask->sig;
207
208	/*
209	* Handle the first word specially: it contains the
210	* synchronous signals that need to be dequeued first.
211	*/
212	x = *s &~ *m;
213	if (x) {
214	if (x & SYNCHRONOUS_MASK)
215	x &= SYNCHRONOUS_MASK;
216	sig = ffz(~x) + 1;
217	return sig;
218	}
219
220	switch (_NSIG_WORDS) {
221	default:
222	for (i = 1; i < _NSIG_WORDS; ++i) {
223	x = *++s &~ *++m;
224	if (!x)
225	continue;
226	sig = ffz(~x) + i*_NSIG_BPW + 1;
227	break;
228	}
229	break;
230
231	case 2:
232	x = s[1] &~ m[1];
233	if (!x)
234	break;
235	sig = ffz(~x) + _NSIG_BPW + 1;
236	break;
237
238	case 1:
239	/* Nothing to do */
240	break;
241	}
242
243	return sig;
244	}
245
246	static inline void print_dropped_signal(int sig)
247	{
248	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
249
250	if (!print_fatal_signals)
251	return;
252
253	if (!__ratelimit(&ratelimit_state))
254	return;
255
256	pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
257	current->comm, current->pid, sig);
258	}
259
260	/**
261	* task_set_jobctl_pending - set jobctl pending bits
262	* @task: target task
263	* @mask: pending bits to set
264	*
265	* Clear @mask from @task->jobctl. @mask must be subset of
266	* %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
267	* %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
268	* cleared. If @task is already being killed or exiting, this function
269	* becomes noop.
270	*
271	* CONTEXT:
272	* Must be called with @task->sighand->siglock held.
273	*
274	* RETURNS:
275	* %true if @mask is set, %false if made noop because @task was dying.
276	*/
277	bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
278	{
279	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
280	JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
281	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
282
283	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
284	return false;
285
286	if (mask & JOBCTL_STOP_SIGMASK)
287	task->jobctl &= ~JOBCTL_STOP_SIGMASK;
288
289	task->jobctl |= mask;
290	return true;
291	}
292
293	/**
294	* task_clear_jobctl_trapping - clear jobctl trapping bit
295	* @task: target task
296	*
297	* If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
298	* Clear it and wake up the ptracer. Note that we don't need any further
299	* locking. @task->siglock guarantees that @task->parent points to the
300	* ptracer.
301	*
302	* CONTEXT:
303	* Must be called with @task->sighand->siglock held.
304	*/
305	void task_clear_jobctl_trapping(struct task_struct *task)
306	{
307	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
308	task->jobctl &= ~JOBCTL_TRAPPING;
309	smp_mb(); /* advised by wake_up_bit() */
310	wake_up_bit(word: &task->jobctl, JOBCTL_TRAPPING_BIT);
311	}
312	}
313
314	/**
315	* task_clear_jobctl_pending - clear jobctl pending bits
316	* @task: target task
317	* @mask: pending bits to clear
318	*
319	* Clear @mask from @task->jobctl. @mask must be subset of
320	* %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
321	* STOP bits are cleared together.
322	*
323	* If clearing of @mask leaves no stop or trap pending, this function calls
324	* task_clear_jobctl_trapping().
325	*
326	* CONTEXT:
327	* Must be called with @task->sighand->siglock held.
328	*/
329	void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
330	{
331	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
332
333	if (mask & JOBCTL_STOP_PENDING)
334	mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
335
336	task->jobctl &= ~mask;
337
338	if (!(task->jobctl & JOBCTL_PENDING_MASK))
339	task_clear_jobctl_trapping(task);
340	}
341
342	/**
343	* task_participate_group_stop - participate in a group stop
344	* @task: task participating in a group stop
345	*
346	* @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
347	* Group stop states are cleared and the group stop count is consumed if
348	* %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
349	* stop, the appropriate `SIGNAL_*` flags are set.
350	*
351	* CONTEXT:
352	* Must be called with @task->sighand->siglock held.
353	*
354	* RETURNS:
355	* %true if group stop completion should be notified to the parent, %false
356	* otherwise.
357	*/
358	static bool task_participate_group_stop(struct task_struct *task)
359	{
360	struct signal_struct *sig = task->signal;
361	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
362
363	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
364
365	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
366
367	if (!consume)
368	return false;
369
370	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
371	sig->group_stop_count--;
372
373	/*
374	* Tell the caller to notify completion iff we are entering into a
375	* fresh group stop. Read comment in do_signal_stop() for details.
376	*/
377	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
378	signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
379	return true;
380	}
381	return false;
382	}
383
384	void task_join_group_stop(struct task_struct *task)
385	{
386	unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
387	struct signal_struct *sig = current->signal;
388
389	if (sig->group_stop_count) {
390	sig->group_stop_count++;
391	mask |= JOBCTL_STOP_CONSUME;
392	} else if (!(sig->flags & SIGNAL_STOP_STOPPED))
393	return;
394
395	/* Have the new thread join an on-going signal group stop */
396	task_set_jobctl_pending(task, mask: mask | JOBCTL_STOP_PENDING);
397	}
398
399	/*
400	* allocate a new signal queue record
401	* - this may be called without locks if and only if t == current, otherwise an
402	* appropriate lock must be held to stop the target task from exiting
403	*/
404	static struct sigqueue *
405	__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
406	int override_rlimit, const unsigned int sigqueue_flags)
407	{
408	struct sigqueue *q = NULL;
409	struct ucounts *ucounts;
410	long sigpending;
411
412	/*
413	* Protect access to @t credentials. This can go away when all
414	* callers hold rcu read lock.
415	*
416	* NOTE! A pending signal will hold on to the user refcount,
417	* and we get/put the refcount only when the sigpending count
418	* changes from/to zero.
419	*/
420	rcu_read_lock();
421	ucounts = task_ucounts(t);
422	sigpending = inc_rlimit_get_ucounts(ucounts, type: UCOUNT_RLIMIT_SIGPENDING);
423	rcu_read_unlock();
424	if (!sigpending)
425	return NULL;
426
427	if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
428	q = kmem_cache_alloc(cachep: sigqueue_cachep, flags: gfp_flags);
429	} else {
430	print_dropped_signal(sig);
431	}
432
433	if (unlikely(q == NULL)) {
434	dec_rlimit_put_ucounts(ucounts, type: UCOUNT_RLIMIT_SIGPENDING);
435	} else {
436	INIT_LIST_HEAD(list: &q->list);
437	q->flags = sigqueue_flags;
438	q->ucounts = ucounts;
439	}
440	return q;
441	}
442
443	static void __sigqueue_free(struct sigqueue *q)
444	{
445	if (q->flags & SIGQUEUE_PREALLOC)
446	return;
447	if (q->ucounts) {
448	dec_rlimit_put_ucounts(ucounts: q->ucounts, type: UCOUNT_RLIMIT_SIGPENDING);
449	q->ucounts = NULL;
450	}
451	kmem_cache_free(s: sigqueue_cachep, objp: q);
452	}
453
454	void flush_sigqueue(struct sigpending *queue)
455	{
456	struct sigqueue *q;
457
458	sigemptyset(set: &queue->signal);
459	while (!list_empty(head: &queue->list)) {
460	q = list_entry(queue->list.next, struct sigqueue , list);
461	list_del_init(entry: &q->list);
462	__sigqueue_free(q);
463	}
464	}
465
466	/*
467	* Flush all pending signals for this kthread.
468	*/
469	void flush_signals(struct task_struct *t)
470	{
471	unsigned long flags;
472
473	spin_lock_irqsave(&t->sighand->siglock, flags);
474	clear_tsk_thread_flag(tsk: t, TIF_SIGPENDING);
475	flush_sigqueue(queue: &t->pending);
476	flush_sigqueue(queue: &t->signal->shared_pending);
477	spin_unlock_irqrestore(lock: &t->sighand->siglock, flags);
478	}
479	EXPORT_SYMBOL(flush_signals);
480
481	#ifdef CONFIG_POSIX_TIMERS
482	static void __flush_itimer_signals(struct sigpending *pending)
483	{
484	sigset_t signal, retain;
485	struct sigqueue *q, *n;
486
487	signal = pending->signal;
488	sigemptyset(set: &retain);
489
490	list_for_each_entry_safe(q, n, &pending->list, list) {
491	int sig = q->info.si_signo;
492
493	if (likely(q->info.si_code != SI_TIMER)) {
494	sigaddset(set: &retain, sig: sig);
495	} else {
496	sigdelset(set: &signal, sig: sig);
497	list_del_init(entry: &q->list);
498	__sigqueue_free(q);
499	}
500	}
501
502	sigorsets(r: &pending->signal, a: &signal, b: &retain);
503	}
504
505	void flush_itimer_signals(void)
506	{
507	struct task_struct *tsk = current;
508	unsigned long flags;
509
510	spin_lock_irqsave(&tsk->sighand->siglock, flags);
511	__flush_itimer_signals(pending: &tsk->pending);
512	__flush_itimer_signals(pending: &tsk->signal->shared_pending);
513	spin_unlock_irqrestore(lock: &tsk->sighand->siglock, flags);
514	}
515	#endif
516
517	void ignore_signals(struct task_struct *t)
518	{
519	int i;
520
521	for (i = 0; i < _NSIG; ++i)
522	t->sighand->action[i].sa.sa_handler = SIG_IGN;
523
524	flush_signals(t);
525	}
526
527	/*
528	* Flush all handlers for a task.
529	*/
530
531	void
532	flush_signal_handlers(struct task_struct *t, int force_default)
533	{
534	int i;
535	struct k_sigaction *ka = &t->sighand->action[0];
536	for (i = _NSIG ; i != 0 ; i--) {
537	if (force_default || ka->sa.sa_handler != SIG_IGN)
538	ka->sa.sa_handler = SIG_DFL;
539	ka->sa.sa_flags = 0;
540	#ifdef __ARCH_HAS_SA_RESTORER
541	ka->sa.sa_restorer = NULL;
542	#endif
543	sigemptyset(set: &ka->sa.sa_mask);
544	ka++;
545	}
546	}
547
548	bool unhandled_signal(struct task_struct *tsk, int sig)
549	{
550	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
551	if (is_global_init(tsk))
552	return true;
553
554	if (handler != SIG_IGN && handler != SIG_DFL)
555	return false;
556
557	/* If dying, we handle all new signals by ignoring them */
558	if (fatal_signal_pending(p: tsk))
559	return false;
560
561	/* if ptraced, let the tracer determine */
562	return !tsk->ptrace;
563	}
564
565	static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
566	bool *resched_timer)
567	{
568	struct sigqueue *q, *first = NULL;
569
570	/*
571	* Collect the siginfo appropriate to this signal. Check if
572	* there is another siginfo for the same signal.
573	*/
574	list_for_each_entry(q, &list->list, list) {
575	if (q->info.si_signo == sig) {
576	if (first)
577	goto still_pending;
578	first = q;
579	}
580	}
581
582	sigdelset(set: &list->signal, sig: sig);
583
584	if (first) {
585	still_pending:
586	list_del_init(entry: &first->list);
587	copy_siginfo(to: info, from: &first->info);
588
589	*resched_timer =
590	(first->flags & SIGQUEUE_PREALLOC) &&
591	(info->si_code == SI_TIMER) &&
592	(info->si_sys_private);
593
594	__sigqueue_free(q: first);
595	} else {
596	/*
597	* Ok, it wasn't in the queue. This must be
598	* a fast-pathed signal or we must have been
599	* out of queue space. So zero out the info.
600	*/
601	clear_siginfo(info);
602	info->si_signo = sig;
603	info->si_errno = 0;
604	info->si_code = SI_USER;
605	info->si_pid = 0;
606	info->si_uid = 0;
607	}
608	}
609
610	static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
611	kernel_siginfo_t *info, bool *resched_timer)
612	{
613	int sig = next_signal(pending, mask);
614
615	if (sig)
616	collect_signal(sig, list: pending, info, resched_timer);
617	return sig;
618	}
619
620	/*
621	* Dequeue a signal and return the element to the caller, which is
622	* expected to free it.
623	*
624	* All callers have to hold the siglock.
625	*/
626	int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
627	kernel_siginfo_t *info, enum pid_type *type)
628	{
629	bool resched_timer = false;
630	int signr;
631
632	/* We only dequeue private signals from ourselves, we don't let
633	* signalfd steal them
634	*/
635	*type = PIDTYPE_PID;
636	signr = __dequeue_signal(pending: &tsk->pending, mask, info, resched_timer: &resched_timer);
637	if (!signr) {
638	*type = PIDTYPE_TGID;
639	signr = __dequeue_signal(pending: &tsk->signal->shared_pending,
640	mask, info, resched_timer: &resched_timer);
641	#ifdef CONFIG_POSIX_TIMERS
642	/*
643	* itimer signal ?
644	*
645	* itimers are process shared and we restart periodic
646	* itimers in the signal delivery path to prevent DoS
647	* attacks in the high resolution timer case. This is
648	* compliant with the old way of self-restarting
649	* itimers, as the SIGALRM is a legacy signal and only
650	* queued once. Changing the restart behaviour to
651	* restart the timer in the signal dequeue path is
652	* reducing the timer noise on heavy loaded !highres
653	* systems too.
654	*/
655	if (unlikely(signr == SIGALRM)) {
656	struct hrtimer *tmr = &tsk->signal->real_timer;
657
658	if (!hrtimer_is_queued(timer: tmr) &&
659	tsk->signal->it_real_incr != 0) {
660	hrtimer_forward(timer: tmr, now: tmr->base->get_time(),
661	interval: tsk->signal->it_real_incr);
662	hrtimer_restart(timer: tmr);
663	}
664	}
665	#endif
666	}
667
668	recalc_sigpending();
669	if (!signr)
670	return 0;
671
672	if (unlikely(sig_kernel_stop(signr))) {
673	/*
674	* Set a marker that we have dequeued a stop signal. Our
675	* caller might release the siglock and then the pending
676	* stop signal it is about to process is no longer in the
677	* pending bitmasks, but must still be cleared by a SIGCONT
678	* (and overruled by a SIGKILL). So those cases clear this
679	* shared flag after we've set it. Note that this flag may
680	* remain set after the signal we return is ignored or
681	* handled. That doesn't matter because its only purpose
682	* is to alert stop-signal processing code when another
683	* processor has come along and cleared the flag.
684	*/
685	current->jobctl |= JOBCTL_STOP_DEQUEUED;
686	}
687	#ifdef CONFIG_POSIX_TIMERS
688	if (resched_timer) {
689	/*
690	* Release the siglock to ensure proper locking order
691	* of timer locks outside of siglocks. Note, we leave
692	* irqs disabled here, since the posix-timers code is
693	* about to disable them again anyway.
694	*/
695	spin_unlock(lock: &tsk->sighand->siglock);
696	posixtimer_rearm(info);
697	spin_lock(lock: &tsk->sighand->siglock);
698
699	/* Don't expose the si_sys_private value to userspace */
700	info->si_sys_private = 0;
701	}
702	#endif
703	return signr;
704	}
705	EXPORT_SYMBOL_GPL(dequeue_signal);
706
707	static int dequeue_synchronous_signal(kernel_siginfo_t *info)
708	{
709	struct task_struct *tsk = current;
710	struct sigpending *pending = &tsk->pending;
711	struct sigqueue *q, *sync = NULL;
712
713	/*
714	* Might a synchronous signal be in the queue?
715	*/
716	if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
717	return 0;
718
719	/*
720	* Return the first synchronous signal in the queue.
721	*/
722	list_for_each_entry(q, &pending->list, list) {
723	/* Synchronous signals have a positive si_code */
724	if ((q->info.si_code > SI_USER) &&
725	(sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
726	sync = q;
727	goto next;
728	}
729	}
730	return 0;
731	next:
732	/*
733	* Check if there is another siginfo for the same signal.
734	*/
735	list_for_each_entry_continue(q, &pending->list, list) {
736	if (q->info.si_signo == sync->info.si_signo)
737	goto still_pending;
738	}
739
740	sigdelset(set: &pending->signal, sig: sync->info.si_signo);
741	recalc_sigpending();
742	still_pending:
743	list_del_init(entry: &sync->list);
744	copy_siginfo(to: info, from: &sync->info);
745	__sigqueue_free(q: sync);
746	return info->si_signo;
747	}
748
749	/*
750	* Tell a process that it has a new active signal..
751	*
752	* NOTE! we rely on the previous spin_lock to
753	* lock interrupts for us! We can only be called with
754	* "siglock" held, and the local interrupt must
755	* have been disabled when that got acquired!
756	*
757	* No need to set need_resched since signal event passing
758	* goes through ->blocked
759	*/
760	void signal_wake_up_state(struct task_struct *t, unsigned int state)
761	{
762	lockdep_assert_held(&t->sighand->siglock);
763
764	set_tsk_thread_flag(tsk: t, TIF_SIGPENDING);
765
766	/*
767	* TASK_WAKEKILL also means wake it up in the stopped/traced/killable
768	* case. We don't check t->state here because there is a race with it
769	* executing another processor and just now entering stopped state.
770	* By using wake_up_state, we ensure the process will wake up and
771	* handle its death signal.
772	*/
773	if (!wake_up_state(tsk: t, state: state | TASK_INTERRUPTIBLE))
774	kick_process(tsk: t);
775	}
776
777	/*
778	* Remove signals in mask from the pending set and queue.
779	* Returns 1 if any signals were found.
780	*
781	* All callers must be holding the siglock.
782	*/
783	static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
784	{
785	struct sigqueue *q, *n;
786	sigset_t m;
787
788	sigandsets(r: &m, a: mask, b: &s->signal);
789	if (sigisemptyset(set: &m))
790	return;
791
792	sigandnsets(r: &s->signal, a: &s->signal, b: mask);
793	list_for_each_entry_safe(q, n, &s->list, list) {
794	if (sigismember(set: mask, sig: q->info.si_signo)) {
795	list_del_init(entry: &q->list);
796	__sigqueue_free(q);
797	}
798	}
799	}
800
801	static inline int is_si_special(const struct kernel_siginfo *info)
802	{
803	return info <= SEND_SIG_PRIV;
804	}
805
806	static inline bool si_fromuser(const struct kernel_siginfo *info)
807	{
808	return info == SEND_SIG_NOINFO ||
809	(!is_si_special(info) && SI_FROMUSER(info));
810	}
811
812	/*
813	* called with RCU read lock from check_kill_permission()
814	*/
815	static bool kill_ok_by_cred(struct task_struct *t)
816	{
817	const struct cred *cred = current_cred();
818	const struct cred *tcred = __task_cred(t);
819
820	return uid_eq(left: cred->euid, right: tcred->suid) ||
821	uid_eq(left: cred->euid, right: tcred->uid) ||
822	uid_eq(left: cred->uid, right: tcred->suid) ||
823	uid_eq(left: cred->uid, right: tcred->uid) ||
824	ns_capable(ns: tcred->user_ns, CAP_KILL);
825	}
826
827	/*
828	* Bad permissions for sending the signal
829	* - the caller must hold the RCU read lock
830	*/
831	static int check_kill_permission(int sig, struct kernel_siginfo *info,
832	struct task_struct *t)
833	{
834	struct pid *sid;
835	int error;
836
837	if (!valid_signal(sig))
838	return -EINVAL;
839
840	if (!si_fromuser(info))
841	return 0;
842
843	error = audit_signal_info(sig, t); /* Let audit system see the signal */
844	if (error)
845	return error;
846
847	if (!same_thread_group(current, p2: t) &&
848	!kill_ok_by_cred(t)) {
849	switch (sig) {
850	case SIGCONT:
851	sid = task_session(task: t);
852	/*
853	* We don't return the error if sid == NULL. The
854	* task was unhashed, the caller must notice this.
855	*/
856	if (!sid || sid == task_session(current))
857	break;
858	fallthrough;
859	default:
860	return -EPERM;
861	}
862	}
863
864	return security_task_kill(p: t, info, sig, NULL);
865	}
866
867	/**
868	* ptrace_trap_notify - schedule trap to notify ptracer
869	* @t: tracee wanting to notify tracer
870	*
871	* This function schedules sticky ptrace trap which is cleared on the next
872	* TRAP_STOP to notify ptracer of an event. @t must have been seized by
873	* ptracer.
874	*
875	* If @t is running, STOP trap will be taken. If trapped for STOP and
876	* ptracer is listening for events, tracee is woken up so that it can
877	* re-trap for the new event. If trapped otherwise, STOP trap will be
878	* eventually taken without returning to userland after the existing traps
879	* are finished by PTRACE_CONT.
880	*
881	* CONTEXT:
882	* Must be called with @task->sighand->siglock held.
883	*/
884	static void ptrace_trap_notify(struct task_struct *t)
885	{
886	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
887	lockdep_assert_held(&t->sighand->siglock);
888
889	task_set_jobctl_pending(task: t, JOBCTL_TRAP_NOTIFY);
890	ptrace_signal_wake_up(t, resume: t->jobctl & JOBCTL_LISTENING);
891	}
892
893	/*
894	* Handle magic process-wide effects of stop/continue signals. Unlike
895	* the signal actions, these happen immediately at signal-generation
896	* time regardless of blocking, ignoring, or handling. This does the
897	* actual continuing for SIGCONT, but not the actual stopping for stop
898	* signals. The process stop is done as a signal action for SIG_DFL.
899	*
900	* Returns true if the signal should be actually delivered, otherwise
901	* it should be dropped.
902	*/
903	static bool prepare_signal(int sig, struct task_struct *p, bool force)
904	{
905	struct signal_struct *signal = p->signal;
906	struct task_struct *t;
907	sigset_t flush;
908
909	if (signal->flags & SIGNAL_GROUP_EXIT) {
910	if (signal->core_state)
911	return sig == SIGKILL;
912	/*
913	* The process is in the middle of dying, drop the signal.
914	*/
915	return false;
916	} else if (sig_kernel_stop(sig)) {
917	/*
918	* This is a stop signal. Remove SIGCONT from all queues.
919	*/
920	siginitset(set: &flush, sigmask(SIGCONT));
921	flush_sigqueue_mask(mask: &flush, s: &signal->shared_pending);
922	for_each_thread(p, t)
923	flush_sigqueue_mask(mask: &flush, s: &t->pending);
924	} else if (sig == SIGCONT) {
925	unsigned int why;
926	/*
927	* Remove all stop signals from all queues, wake all threads.
928	*/
929	siginitset(set: &flush, SIG_KERNEL_STOP_MASK);
930	flush_sigqueue_mask(mask: &flush, s: &signal->shared_pending);
931	for_each_thread(p, t) {
932	flush_sigqueue_mask(mask: &flush, s: &t->pending);
933	task_clear_jobctl_pending(task: t, JOBCTL_STOP_PENDING);
934	if (likely(!(t->ptrace & PT_SEIZED))) {
935	t->jobctl &= ~JOBCTL_STOPPED;
936	wake_up_state(tsk: t, __TASK_STOPPED);
937	} else
938	ptrace_trap_notify(t);
939	}
940
941	/*
942	* Notify the parent with CLD_CONTINUED if we were stopped.
943	*
944	* If we were in the middle of a group stop, we pretend it
945	* was already finished, and then continued. Since SIGCHLD
946	* doesn't queue we report only CLD_STOPPED, as if the next
947	* CLD_CONTINUED was dropped.
948	*/
949	why = 0;
950	if (signal->flags & SIGNAL_STOP_STOPPED)
951	why |= SIGNAL_CLD_CONTINUED;
952	else if (signal->group_stop_count)
953	why |= SIGNAL_CLD_STOPPED;
954
955	if (why) {
956	/*
957	* The first thread which returns from do_signal_stop()
958	* will take ->siglock, notice SIGNAL_CLD_MASK, and
959	* notify its parent. See get_signal().
960	*/
961	signal_set_stop_flags(sig: signal, flags: why | SIGNAL_STOP_CONTINUED);
962	signal->group_stop_count = 0;
963	signal->group_exit_code = 0;
964	}
965	}
966
967	return !sig_ignored(t: p, sig, force);
968	}
969
970	/*
971	* Test if P wants to take SIG. After we've checked all threads with this,
972	* it's equivalent to finding no threads not blocking SIG. Any threads not
973	* blocking SIG were ruled out because they are not running and already
974	* have pending signals. Such threads will dequeue from the shared queue
975	* as soon as they're available, so putting the signal on the shared queue
976	* will be equivalent to sending it to one such thread.
977	*/
978	static inline bool wants_signal(int sig, struct task_struct *p)
979	{
980	if (sigismember(set: &p->blocked, sig: sig))
981	return false;
982
983	if (p->flags & PF_EXITING)
984	return false;
985
986	if (sig == SIGKILL)
987	return true;
988
989	if (task_is_stopped_or_traced(p))
990	return false;
991
992	return task_curr(p) || !task_sigpending(p);
993	}
994
995	static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
996	{
997	struct signal_struct *signal = p->signal;
998	struct task_struct *t;
999
1000	/*
1001	* Now find a thread we can wake up to take the signal off the queue.
1002	*
1003	* Try the suggested task first (may or may not be the main thread).
1004	*/
1005	if (wants_signal(sig, p))
1006	t = p;
1007	else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1008	/*
1009	* There is just one thread and it does not need to be woken.
1010	* It will dequeue unblocked signals before it runs again.
1011	*/
1012	return;
1013	else {
1014	/*
1015	* Otherwise try to find a suitable thread.
1016	*/
1017	t = signal->curr_target;
1018	while (!wants_signal(sig, p: t)) {
1019	t = next_thread(p: t);
1020	if (t == signal->curr_target)
1021	/*
1022	* No thread needs to be woken.
1023	* Any eligible threads will see
1024	* the signal in the queue soon.
1025	*/
1026	return;
1027	}
1028	signal->curr_target = t;
1029	}
1030
1031	/*
1032	* Found a killable thread. If the signal will be fatal,
1033	* then start taking the whole group down immediately.
1034	*/
1035	if (sig_fatal(p, sig) &&
1036	(signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1037	!sigismember(set: &t->real_blocked, sig: sig) &&
1038	(sig == SIGKILL || !p->ptrace)) {
1039	/*
1040	* This signal will be fatal to the whole group.
1041	*/
1042	if (!sig_kernel_coredump(sig)) {
1043	/*
1044	* Start a group exit and wake everybody up.
1045	* This way we don't have other threads
1046	* running and doing things after a slower
1047	* thread has the fatal signal pending.
1048	*/
1049	signal->flags = SIGNAL_GROUP_EXIT;
1050	signal->group_exit_code = sig;
1051	signal->group_stop_count = 0;
1052	__for_each_thread(signal, t) {
1053	task_clear_jobctl_pending(task: t, JOBCTL_PENDING_MASK);
1054	sigaddset(set: &t->pending.signal, SIGKILL);
1055	signal_wake_up(t, fatal: 1);
1056	}
1057	return;
1058	}
1059	}
1060
1061	/*
1062	* The signal is already in the shared-pending queue.
1063	* Tell the chosen thread to wake up and dequeue it.
1064	*/
1065	signal_wake_up(t, fatal: sig == SIGKILL);
1066	return;
1067	}
1068
1069	static inline bool legacy_queue(struct sigpending *signals, int sig)
1070	{
1071	return (sig < SIGRTMIN) && sigismember(set: &signals->signal, sig: sig);
1072	}
1073
1074	static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1075	struct task_struct *t, enum pid_type type, bool force)
1076	{
1077	struct sigpending *pending;
1078	struct sigqueue *q;
1079	int override_rlimit;
1080	int ret = 0, result;
1081
1082	lockdep_assert_held(&t->sighand->siglock);
1083
1084	result = TRACE_SIGNAL_IGNORED;
1085	if (!prepare_signal(sig, p: t, force))
1086	goto ret;
1087
1088	pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1089	/*
1090	* Short-circuit ignored signals and support queuing
1091	* exactly one non-rt signal, so that we can get more
1092	* detailed information about the cause of the signal.
1093	*/
1094	result = TRACE_SIGNAL_ALREADY_PENDING;
1095	if (legacy_queue(signals: pending, sig))
1096	goto ret;
1097
1098	result = TRACE_SIGNAL_DELIVERED;
1099	/*
1100	* Skip useless siginfo allocation for SIGKILL and kernel threads.
1101	*/
1102	if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1103	goto out_set;
1104
1105	/*
1106	* Real-time signals must be queued if sent by sigqueue, or
1107	* some other real-time mechanism. It is implementation
1108	* defined whether kill() does so. We attempt to do so, on
1109	* the principle of least surprise, but since kill is not
1110	* allowed to fail with EAGAIN when low on memory we just
1111	* make sure at least one signal gets delivered and don't
1112	* pass on the info struct.
1113	*/
1114	if (sig < SIGRTMIN)
1115	override_rlimit = (is_si_special(info) || info->si_code >= 0);
1116	else
1117	override_rlimit = 0;
1118
1119	q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, sigqueue_flags: 0);
1120
1121	if (q) {
1122	list_add_tail(new: &q->list, head: &pending->list);
1123	switch ((unsigned long) info) {
1124	case (unsigned long) SEND_SIG_NOINFO:
1125	clear_siginfo(info: &q->info);
1126	q->info.si_signo = sig;
1127	q->info.si_errno = 0;
1128	q->info.si_code = SI_USER;
1129	q->info.si_pid = task_tgid_nr_ns(current,
1130	ns: task_active_pid_ns(tsk: t));
1131	rcu_read_lock();
1132	q->info.si_uid =
1133	from_kuid_munged(task_cred_xxx(t, user_ns),
1134	current_uid());
1135	rcu_read_unlock();
1136	break;
1137	case (unsigned long) SEND_SIG_PRIV:
1138	clear_siginfo(info: &q->info);
1139	q->info.si_signo = sig;
1140	q->info.si_errno = 0;
1141	q->info.si_code = SI_KERNEL;
1142	q->info.si_pid = 0;
1143	q->info.si_uid = 0;
1144	break;
1145	default:
1146	copy_siginfo(to: &q->info, from: info);
1147	break;
1148	}
1149	} else if (!is_si_special(info) &&
1150	sig >= SIGRTMIN && info->si_code != SI_USER) {
1151	/*
1152	* Queue overflow, abort. We may abort if the
1153	* signal was rt and sent by user using something
1154	* other than kill().
1155	*/
1156	result = TRACE_SIGNAL_OVERFLOW_FAIL;
1157	ret = -EAGAIN;
1158	goto ret;
1159	} else {
1160	/*
1161	* This is a silent loss of information. We still
1162	* send the signal, but the *info bits are lost.
1163	*/
1164	result = TRACE_SIGNAL_LOSE_INFO;
1165	}
1166
1167	out_set:
1168	signalfd_notify(tsk: t, sig);
1169	sigaddset(set: &pending->signal, sig: sig);
1170
1171	/* Let multiprocess signals appear after on-going forks */
1172	if (type > PIDTYPE_TGID) {
1173	struct multiprocess_signals *delayed;
1174	hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1175	sigset_t *signal = &delayed->signal;
1176	/* Can't queue both a stop and a continue signal */
1177	if (sig == SIGCONT)
1178	sigdelsetmask(set: signal, SIG_KERNEL_STOP_MASK);
1179	else if (sig_kernel_stop(sig))
1180	sigdelset(set: signal, SIGCONT);
1181	sigaddset(set: signal, sig: sig);
1182	}
1183	}
1184
1185	complete_signal(sig, p: t, type);
1186	ret:
1187	trace_signal_generate(sig, info, task: t, group: type != PIDTYPE_PID, result);
1188	return ret;
1189	}
1190
1191	static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1192	{
1193	bool ret = false;
1194	switch (siginfo_layout(sig: info->si_signo, si_code: info->si_code)) {
1195	case SIL_KILL:
1196	case SIL_CHLD:
1197	case SIL_RT:
1198	ret = true;
1199	break;
1200	case SIL_TIMER:
1201	case SIL_POLL:
1202	case SIL_FAULT:
1203	case SIL_FAULT_TRAPNO:
1204	case SIL_FAULT_MCEERR:
1205	case SIL_FAULT_BNDERR:
1206	case SIL_FAULT_PKUERR:
1207	case SIL_FAULT_PERF_EVENT:
1208	case SIL_SYS:
1209	ret = false;
1210	break;
1211	}
1212	return ret;
1213	}
1214
1215	int send_signal_locked(int sig, struct kernel_siginfo *info,
1216	struct task_struct *t, enum pid_type type)
1217	{
1218	/* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1219	bool force = false;
1220
1221	if (info == SEND_SIG_NOINFO) {
1222	/* Force if sent from an ancestor pid namespace */
1223	force = !task_pid_nr_ns(current, ns: task_active_pid_ns(tsk: t));
1224	} else if (info == SEND_SIG_PRIV) {
1225	/* Don't ignore kernel generated signals */
1226	force = true;
1227	} else if (has_si_pid_and_uid(info)) {
1228	/* SIGKILL and SIGSTOP is special or has ids */
1229	struct user_namespace *t_user_ns;
1230
1231	rcu_read_lock();
1232	t_user_ns = task_cred_xxx(t, user_ns);
1233	if (current_user_ns() != t_user_ns) {
1234	kuid_t uid = make_kuid(current_user_ns(), uid: info->si_uid);
1235	info->si_uid = from_kuid_munged(to: t_user_ns, uid);
1236	}
1237	rcu_read_unlock();
1238
1239	/* A kernel generated signal? */
1240	force = (info->si_code == SI_KERNEL);
1241
1242	/* From an ancestor pid namespace? */
1243	if (!task_pid_nr_ns(current, ns: task_active_pid_ns(tsk: t))) {
1244	info->si_pid = 0;
1245	force = true;
1246	}
1247	}
1248	return __send_signal_locked(sig, info, t, type, force);
1249	}
1250
1251	static void print_fatal_signal(int signr)
1252	{
1253	struct pt_regs *regs = task_pt_regs(current);
1254	struct file *exe_file;
1255
1256	exe_file = get_task_exe_file(current);
1257	if (exe_file) {
1258	pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1259	exe_file, current->comm, signr);
1260	fput(exe_file);
1261	} else {
1262	pr_info("%s: potentially unexpected fatal signal %d.\n",
1263	current->comm, signr);
1264	}
1265
1266	#if defined(__i386__) && !defined(__arch_um__)
1267	pr_info("code at %08lx: ", regs->ip);
1268	{
1269	int i;
1270	for (i = 0; i < 16; i++) {
1271	unsigned char insn;
1272
1273	if (get_user(insn, (unsigned char *)(regs->ip + i)))
1274	break;
1275	pr_cont("%02x ", insn);
1276	}
1277	}
1278	pr_cont("\n");
1279	#endif
1280	preempt_disable();
1281	show_regs(regs);
1282	preempt_enable();
1283	}
1284
1285	static int __init setup_print_fatal_signals(char *str)
1286	{
1287	get_option (str: &str, pint: &print_fatal_signals);
1288
1289	return 1;
1290	}
1291
1292	__setup("print-fatal-signals=", setup_print_fatal_signals);
1293
1294	int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1295	enum pid_type type)
1296	{
1297	unsigned long flags;
1298	int ret = -ESRCH;
1299
1300	if (lock_task_sighand(task: p, flags: &flags)) {
1301	ret = send_signal_locked(sig, info, t: p, type);
1302	unlock_task_sighand(task: p, flags: &flags);
1303	}
1304
1305	return ret;
1306	}
1307
1308	enum sig_handler {
1309	HANDLER_CURRENT, /* If reachable use the current handler */
1310	HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1311	HANDLER_EXIT, /* Only visible as the process exit code */
1312	};
1313
1314	/*
1315	* Force a signal that the process can't ignore: if necessary
1316	* we unblock the signal and change any SIG_IGN to SIG_DFL.
1317	*
1318	* Note: If we unblock the signal, we always reset it to SIG_DFL,
1319	* since we do not want to have a signal handler that was blocked
1320	* be invoked when user space had explicitly blocked it.
1321	*
1322	* We don't want to have recursive SIGSEGV's etc, for example,
1323	* that is why we also clear SIGNAL_UNKILLABLE.
1324	*/
1325	static int
1326	force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1327	enum sig_handler handler)
1328	{
1329	unsigned long int flags;
1330	int ret, blocked, ignored;
1331	struct k_sigaction *action;
1332	int sig = info->si_signo;
1333
1334	spin_lock_irqsave(&t->sighand->siglock, flags);
1335	action = &t->sighand->action[sig-1];
1336	ignored = action->sa.sa_handler == SIG_IGN;
1337	blocked = sigismember(set: &t->blocked, sig: sig);
1338	if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1339	action->sa.sa_handler = SIG_DFL;
1340	if (handler == HANDLER_EXIT)
1341	action->sa.sa_flags |= SA_IMMUTABLE;
1342	if (blocked)
1343	sigdelset(set: &t->blocked, sig: sig);
1344	}
1345	/*
1346	* Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1347	* debugging to leave init killable. But HANDLER_EXIT is always fatal.
1348	*/
1349	if (action->sa.sa_handler == SIG_DFL &&
1350	(!t->ptrace || (handler == HANDLER_EXIT)))
1351	t->signal->flags &= ~SIGNAL_UNKILLABLE;
1352	ret = send_signal_locked(sig, info, t, type: PIDTYPE_PID);
1353	/* This can happen if the signal was already pending and blocked */
1354	if (!task_sigpending(p: t))
1355	signal_wake_up(t, fatal: 0);
1356	spin_unlock_irqrestore(lock: &t->sighand->siglock, flags);
1357
1358	return ret;
1359	}
1360
1361	int force_sig_info(struct kernel_siginfo *info)
1362	{
1363	return force_sig_info_to_task(info, current, handler: HANDLER_CURRENT);
1364	}
1365
1366	/*
1367	* Nuke all other threads in the group.
1368	*/
1369	int zap_other_threads(struct task_struct *p)
1370	{
1371	struct task_struct *t;
1372	int count = 0;
1373
1374	p->signal->group_stop_count = 0;
1375
1376	for_other_threads(p, t) {
1377	task_clear_jobctl_pending(task: t, JOBCTL_PENDING_MASK);
1378	/* Don't require de_thread to wait for the vhost_worker */
1379	if ((t->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)
1380	count++;
1381
1382	/* Don't bother with already dead threads */
1383	if (t->exit_state)
1384	continue;
1385	sigaddset(set: &t->pending.signal, SIGKILL);
1386	signal_wake_up(t, fatal: 1);
1387	}
1388
1389	return count;
1390	}
1391
1392	struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1393	unsigned long *flags)
1394	{
1395	struct sighand_struct *sighand;
1396
1397	rcu_read_lock();
1398	for (;;) {
1399	sighand = rcu_dereference(tsk->sighand);
1400	if (unlikely(sighand == NULL))
1401	break;
1402
1403	/*
1404	* This sighand can be already freed and even reused, but
1405	* we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1406	* initializes ->siglock: this slab can't go away, it has
1407	* the same object type, ->siglock can't be reinitialized.
1408	*
1409	* We need to ensure that tsk->sighand is still the same
1410	* after we take the lock, we can race with de_thread() or
1411	* __exit_signal(). In the latter case the next iteration
1412	* must see ->sighand == NULL.
1413	*/
1414	spin_lock_irqsave(&sighand->siglock, *flags);
1415	if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1416	break;
1417	spin_unlock_irqrestore(lock: &sighand->siglock, flags: *flags);
1418	}
1419	rcu_read_unlock();
1420
1421	return sighand;
1422	}
1423
1424	#ifdef CONFIG_LOCKDEP
1425	void lockdep_assert_task_sighand_held(struct task_struct *task)
1426	{
1427	struct sighand_struct *sighand;
1428
1429	rcu_read_lock();
1430	sighand = rcu_dereference(task->sighand);
1431	if (sighand)
1432	lockdep_assert_held(&sighand->siglock);
1433	else
1434	WARN_ON_ONCE(1);
1435	rcu_read_unlock();
1436	}
1437	#endif
1438
1439	/*
1440	* send signal info to all the members of a thread group or to the
1441	* individual thread if type == PIDTYPE_PID.
1442	*/
1443	int group_send_sig_info(int sig, struct kernel_siginfo *info,
1444	struct task_struct *p, enum pid_type type)
1445	{
1446	int ret;
1447
1448	rcu_read_lock();
1449	ret = check_kill_permission(sig, info, t: p);
1450	rcu_read_unlock();
1451
1452	if (!ret && sig)
1453	ret = do_send_sig_info(sig, info, p, type);
1454
1455	return ret;
1456	}
1457
1458	/*
1459	* __kill_pgrp_info() sends a signal to a process group: this is what the tty
1460	* control characters do (^C, ^Z etc)
1461	* - the caller must hold at least a readlock on tasklist_lock
1462	*/
1463	int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1464	{
1465	struct task_struct *p = NULL;
1466	int ret = -ESRCH;
1467
1468	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1469	int err = group_send_sig_info(sig, info, p, type: PIDTYPE_PGID);
1470	/*
1471	* If group_send_sig_info() succeeds at least once ret
1472	* becomes 0 and after that the code below has no effect.
1473	* Otherwise we return the last err or -ESRCH if this
1474	* process group is empty.
1475	*/
1476	if (ret)
1477	ret = err;
1478	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1479
1480	return ret;
1481	}
1482
1483	static int kill_pid_info_type(int sig, struct kernel_siginfo *info,
1484	struct pid *pid, enum pid_type type)
1485	{
1486	int error = -ESRCH;
1487	struct task_struct *p;
1488
1489	for (;;) {
1490	rcu_read_lock();
1491	p = pid_task(pid, PIDTYPE_PID);
1492	if (p)
1493	error = group_send_sig_info(sig, info, p, type);
1494	rcu_read_unlock();
1495	if (likely(!p || error != -ESRCH))
1496	return error;
1497	/*
1498	* The task was unhashed in between, try again. If it
1499	* is dead, pid_task() will return NULL, if we race with
1500	* de_thread() it will find the new leader.
1501	*/
1502	}
1503	}
1504
1505	int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1506	{
1507	return kill_pid_info_type(sig, info, pid, type: PIDTYPE_TGID);
1508	}
1509
1510	static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1511	{
1512	int error;
1513	rcu_read_lock();
1514	error = kill_pid_info(sig, info, pid: find_vpid(nr: pid));
1515	rcu_read_unlock();
1516	return error;
1517	}
1518
1519	static inline bool kill_as_cred_perm(const struct cred *cred,
1520	struct task_struct *target)
1521	{
1522	const struct cred *pcred = __task_cred(target);
1523
1524	return uid_eq(left: cred->euid, right: pcred->suid) ||
1525	uid_eq(left: cred->euid, right: pcred->uid) ||
1526	uid_eq(left: cred->uid, right: pcred->suid) ||
1527	uid_eq(left: cred->uid, right: pcred->uid);
1528	}
1529
1530	/*
1531	* The usb asyncio usage of siginfo is wrong. The glibc support
1532	* for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1533	* AKA after the generic fields:
1534	* kernel_pid_t si_pid;
1535	* kernel_uid32_t si_uid;
1536	* sigval_t si_value;
1537	*
1538	* Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1539	* after the generic fields is:
1540	* void __user *si_addr;
1541	*
1542	* This is a practical problem when there is a 64bit big endian kernel
1543	* and a 32bit userspace. As the 32bit address will encoded in the low
1544	* 32bits of the pointer. Those low 32bits will be stored at higher
1545	* address than appear in a 32 bit pointer. So userspace will not
1546	* see the address it was expecting for it's completions.
1547	*
1548	* There is nothing in the encoding that can allow
1549	* copy_siginfo_to_user32 to detect this confusion of formats, so
1550	* handle this by requiring the caller of kill_pid_usb_asyncio to
1551	* notice when this situration takes place and to store the 32bit
1552	* pointer in sival_int, instead of sival_addr of the sigval_t addr
1553	* parameter.
1554	*/
1555	int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1556	struct pid *pid, const struct cred *cred)
1557	{
1558	struct kernel_siginfo info;
1559	struct task_struct *p;
1560	unsigned long flags;
1561	int ret = -EINVAL;
1562
1563	if (!valid_signal(sig))
1564	return ret;
1565
1566	clear_siginfo(info: &info);
1567	info.si_signo = sig;
1568	info.si_errno = errno;
1569	info.si_code = SI_ASYNCIO;
1570	*((sigval_t *)&info.si_pid) = addr;
1571
1572	rcu_read_lock();
1573	p = pid_task(pid, PIDTYPE_PID);
1574	if (!p) {
1575	ret = -ESRCH;
1576	goto out_unlock;
1577	}
1578	if (!kill_as_cred_perm(cred, target: p)) {
1579	ret = -EPERM;
1580	goto out_unlock;
1581	}
1582	ret = security_task_kill(p, info: &info, sig, cred);
1583	if (ret)
1584	goto out_unlock;
1585
1586	if (sig) {
1587	if (lock_task_sighand(task: p, flags: &flags)) {
1588	ret = __send_signal_locked(sig, info: &info, t: p, type: PIDTYPE_TGID, force: false);
1589	unlock_task_sighand(task: p, flags: &flags);
1590	} else
1591	ret = -ESRCH;
1592	}
1593	out_unlock:
1594	rcu_read_unlock();
1595	return ret;
1596	}
1597	EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1598
1599	/*
1600	* kill_something_info() interprets pid in interesting ways just like kill(2).
1601	*
1602	* POSIX specifies that kill(-1,sig) is unspecified, but what we have
1603	* is probably wrong. Should make it like BSD or SYSV.
1604	*/
1605
1606	static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1607	{
1608	int ret;
1609
1610	if (pid > 0)
1611	return kill_proc_info(sig, info, pid);
1612
1613	/* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1614	if (pid == INT_MIN)
1615	return -ESRCH;
1616
1617	read_lock(&tasklist_lock);
1618	if (pid != -1) {
1619	ret = __kill_pgrp_info(sig, info,
1620	pgrp: pid ? find_vpid(nr: -pid) : task_pgrp(current));
1621	} else {
1622	int retval = 0, count = 0;
1623	struct task_struct * p;
1624
1625	for_each_process(p) {
1626	if (task_pid_vnr(tsk: p) > 1 &&
1627	!same_thread_group(p1: p, current)) {
1628	int err = group_send_sig_info(sig, info, p,
1629	type: PIDTYPE_MAX);
1630	++count;
1631	if (err != -EPERM)
1632	retval = err;
1633	}
1634	}
1635	ret = count ? retval : -ESRCH;
1636	}
1637	read_unlock(&tasklist_lock);
1638
1639	return ret;
1640	}
1641
1642	/*
1643	* These are for backward compatibility with the rest of the kernel source.
1644	*/
1645
1646	int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1647	{
1648	/*
1649	* Make sure legacy kernel users don't send in bad values
1650	* (normal paths check this in check_kill_permission).
1651	*/
1652	if (!valid_signal(sig))
1653	return -EINVAL;
1654
1655	return do_send_sig_info(sig, info, p, type: PIDTYPE_PID);
1656	}
1657	EXPORT_SYMBOL(send_sig_info);
1658
1659	#define __si_special(priv) \
1660	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1661
1662	int
1663	send_sig(int sig, struct task_struct *p, int priv)
1664	{
1665	return send_sig_info(sig, __si_special(priv), p);
1666	}
1667	EXPORT_SYMBOL(send_sig);
1668
1669	void force_sig(int sig)
1670	{
1671	struct kernel_siginfo info;
1672
1673	clear_siginfo(info: &info);
1674	info.si_signo = sig;
1675	info.si_errno = 0;
1676	info.si_code = SI_KERNEL;
1677	info.si_pid = 0;
1678	info.si_uid = 0;
1679	force_sig_info(info: &info);
1680	}
1681	EXPORT_SYMBOL(force_sig);
1682
1683	void force_fatal_sig(int sig)
1684	{
1685	struct kernel_siginfo info;
1686
1687	clear_siginfo(info: &info);
1688	info.si_signo = sig;
1689	info.si_errno = 0;
1690	info.si_code = SI_KERNEL;
1691	info.si_pid = 0;
1692	info.si_uid = 0;
1693	force_sig_info_to_task(info: &info, current, handler: HANDLER_SIG_DFL);
1694	}
1695
1696	void force_exit_sig(int sig)
1697	{
1698	struct kernel_siginfo info;
1699
1700	clear_siginfo(info: &info);
1701	info.si_signo = sig;
1702	info.si_errno = 0;
1703	info.si_code = SI_KERNEL;
1704	info.si_pid = 0;
1705	info.si_uid = 0;
1706	force_sig_info_to_task(info: &info, current, handler: HANDLER_EXIT);
1707	}
1708
1709	/*
1710	* When things go south during signal handling, we
1711	* will force a SIGSEGV. And if the signal that caused
1712	* the problem was already a SIGSEGV, we'll want to
1713	* make sure we don't even try to deliver the signal..
1714	*/
1715	void force_sigsegv(int sig)
1716	{
1717	if (sig == SIGSEGV)
1718	force_fatal_sig(SIGSEGV);
1719	else
1720	force_sig(SIGSEGV);
1721	}
1722
1723	int force_sig_fault_to_task(int sig, int code, void __user *addr,
1724	struct task_struct *t)
1725	{
1726	struct kernel_siginfo info;
1727
1728	clear_siginfo(info: &info);
1729	info.si_signo = sig;
1730	info.si_errno = 0;
1731	info.si_code = code;
1732	info.si_addr = addr;
1733	return force_sig_info_to_task(info: &info, t, handler: HANDLER_CURRENT);
1734	}
1735
1736	int force_sig_fault(int sig, int code, void __user *addr)
1737	{
1738	return force_sig_fault_to_task(sig, code, addr, current);
1739	}
1740
1741	int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t)
1742	{
1743	struct kernel_siginfo info;
1744
1745	clear_siginfo(info: &info);
1746	info.si_signo = sig;
1747	info.si_errno = 0;
1748	info.si_code = code;
1749	info.si_addr = addr;
1750	return send_sig_info(info.si_signo, &info, t);
1751	}
1752
1753	int force_sig_mceerr(int code, void __user *addr, short lsb)
1754	{
1755	struct kernel_siginfo info;
1756
1757	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1758	clear_siginfo(info: &info);
1759	info.si_signo = SIGBUS;
1760	info.si_errno = 0;
1761	info.si_code = code;
1762	info.si_addr = addr;
1763	info.si_addr_lsb = lsb;
1764	return force_sig_info(info: &info);
1765	}
1766
1767	int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1768	{
1769	struct kernel_siginfo info;
1770
1771	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1772	clear_siginfo(info: &info);
1773	info.si_signo = SIGBUS;
1774	info.si_errno = 0;
1775	info.si_code = code;
1776	info.si_addr = addr;
1777	info.si_addr_lsb = lsb;
1778	return send_sig_info(info.si_signo, &info, t);
1779	}
1780	EXPORT_SYMBOL(send_sig_mceerr);
1781
1782	int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1783	{
1784	struct kernel_siginfo info;
1785
1786	clear_siginfo(info: &info);
1787	info.si_signo = SIGSEGV;
1788	info.si_errno = 0;
1789	info.si_code = SEGV_BNDERR;
1790	info.si_addr = addr;
1791	info.si_lower = lower;
1792	info.si_upper = upper;
1793	return force_sig_info(info: &info);
1794	}
1795
1796	#ifdef SEGV_PKUERR
1797	int force_sig_pkuerr(void __user *addr, u32 pkey)
1798	{
1799	struct kernel_siginfo info;
1800
1801	clear_siginfo(info: &info);
1802	info.si_signo = SIGSEGV;
1803	info.si_errno = 0;
1804	info.si_code = SEGV_PKUERR;
1805	info.si_addr = addr;
1806	info.si_pkey = pkey;
1807	return force_sig_info(info: &info);
1808	}
1809	#endif
1810
1811	int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1812	{
1813	struct kernel_siginfo info;
1814
1815	clear_siginfo(info: &info);
1816	info.si_signo = SIGTRAP;
1817	info.si_errno = 0;
1818	info.si_code = TRAP_PERF;
1819	info.si_addr = addr;
1820	info.si_perf_data = sig_data;
1821	info.si_perf_type = type;
1822
1823	/*
1824	* Signals generated by perf events should not terminate the whole
1825	* process if SIGTRAP is blocked, however, delivering the signal
1826	* asynchronously is better than not delivering at all. But tell user
1827	* space if the signal was asynchronous, so it can clearly be
1828	* distinguished from normal synchronous ones.
1829	*/
1830	info.si_perf_flags = sigismember(set: &current->blocked, sig: info.si_signo) ?
1831	TRAP_PERF_FLAG_ASYNC :
1832	0;
1833
1834	return send_sig_info(info.si_signo, &info, current);
1835	}
1836
1837	/**
1838	* force_sig_seccomp - signals the task to allow in-process syscall emulation
1839	* @syscall: syscall number to send to userland
1840	* @reason: filter-supplied reason code to send to userland (via si_errno)
1841	* @force_coredump: true to trigger a coredump
1842	*
1843	* Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1844	*/
1845	int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1846	{
1847	struct kernel_siginfo info;
1848
1849	clear_siginfo(info: &info);
1850	info.si_signo = SIGSYS;
1851	info.si_code = SYS_SECCOMP;
1852	info.si_call_addr = (void __user *)KSTK_EIP(current);
1853	info.si_errno = reason;
1854	info.si_arch = syscall_get_arch(current);
1855	info.si_syscall = syscall;
1856	return force_sig_info_to_task(info: &info, current,
1857	handler: force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1858	}
1859
1860	/* For the crazy architectures that include trap information in
1861	* the errno field, instead of an actual errno value.
1862	*/
1863	int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1864	{
1865	struct kernel_siginfo info;
1866
1867	clear_siginfo(info: &info);
1868	info.si_signo = SIGTRAP;
1869	info.si_errno = errno;
1870	info.si_code = TRAP_HWBKPT;
1871	info.si_addr = addr;
1872	return force_sig_info(info: &info);
1873	}
1874
1875	/* For the rare architectures that include trap information using
1876	* si_trapno.
1877	*/
1878	int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1879	{
1880	struct kernel_siginfo info;
1881
1882	clear_siginfo(info: &info);
1883	info.si_signo = sig;
1884	info.si_errno = 0;
1885	info.si_code = code;
1886	info.si_addr = addr;
1887	info.si_trapno = trapno;
1888	return force_sig_info(info: &info);
1889	}
1890
1891	/* For the rare architectures that include trap information using
1892	* si_trapno.
1893	*/
1894	int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1895	struct task_struct *t)
1896	{
1897	struct kernel_siginfo info;
1898
1899	clear_siginfo(info: &info);
1900	info.si_signo = sig;
1901	info.si_errno = 0;
1902	info.si_code = code;
1903	info.si_addr = addr;
1904	info.si_trapno = trapno;
1905	return send_sig_info(info.si_signo, &info, t);
1906	}
1907
1908	static int kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1909	{
1910	int ret;
1911	read_lock(&tasklist_lock);
1912	ret = __kill_pgrp_info(sig, info, pgrp);
1913	read_unlock(&tasklist_lock);
1914	return ret;
1915	}
1916
1917	int kill_pgrp(struct pid *pid, int sig, int priv)
1918	{
1919	return kill_pgrp_info(sig, __si_special(priv), pgrp: pid);
1920	}
1921	EXPORT_SYMBOL(kill_pgrp);
1922
1923	int kill_pid(struct pid *pid, int sig, int priv)
1924	{
1925	return kill_pid_info(sig, __si_special(priv), pid);
1926	}
1927	EXPORT_SYMBOL(kill_pid);
1928
1929	/*
1930	* These functions support sending signals using preallocated sigqueue
1931	* structures. This is needed "because realtime applications cannot
1932	* afford to lose notifications of asynchronous events, like timer
1933	* expirations or I/O completions". In the case of POSIX Timers
1934	* we allocate the sigqueue structure from the timer_create. If this
1935	* allocation fails we are able to report the failure to the application
1936	* with an EAGAIN error.
1937	*/
1938	struct sigqueue *sigqueue_alloc(void)
1939	{
1940	return __sigqueue_alloc(sig: -1, current, GFP_KERNEL, override_rlimit: 0, SIGQUEUE_PREALLOC);
1941	}
1942
1943	void sigqueue_free(struct sigqueue *q)
1944	{
1945	unsigned long flags;
1946	spinlock_t *lock = &current->sighand->siglock;
1947
1948	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1949	/*
1950	* We must hold ->siglock while testing q->list
1951	* to serialize with collect_signal() or with
1952	* __exit_signal()->flush_sigqueue().
1953	*/
1954	spin_lock_irqsave(lock, flags);
1955	q->flags &= ~SIGQUEUE_PREALLOC;
1956	/*
1957	* If it is queued it will be freed when dequeued,
1958	* like the "regular" sigqueue.
1959	*/
1960	if (!list_empty(head: &q->list))
1961	q = NULL;
1962	spin_unlock_irqrestore(lock, flags);
1963
1964	if (q)
1965	__sigqueue_free(q);
1966	}
1967
1968	int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1969	{
1970	int sig = q->info.si_signo;
1971	struct sigpending *pending;
1972	struct task_struct *t;
1973	unsigned long flags;
1974	int ret, result;
1975
1976	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1977
1978	ret = -1;
1979	rcu_read_lock();
1980
1981	/*
1982	* This function is used by POSIX timers to deliver a timer signal.
1983	* Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1984	* set), the signal must be delivered to the specific thread (queues
1985	* into t->pending).
1986	*
1987	* Where type is not PIDTYPE_PID, signals must be delivered to the
1988	* process. In this case, prefer to deliver to current if it is in
1989	* the same thread group as the target process, which avoids
1990	* unnecessarily waking up a potentially idle task.
1991	*/
1992	t = pid_task(pid, type);
1993	if (!t)
1994	goto ret;
1995	if (type != PIDTYPE_PID && same_thread_group(p1: t, current))
1996	t = current;
1997	if (!likely(lock_task_sighand(t, &flags)))
1998	goto ret;
1999
2000	ret = 1; /* the signal is ignored */
2001	result = TRACE_SIGNAL_IGNORED;
2002	if (!prepare_signal(sig, p: t, force: false))
2003	goto out;
2004
2005	ret = 0;
2006	if (unlikely(!list_empty(&q->list))) {
2007	/*
2008	* If an SI_TIMER entry is already queue just increment
2009	* the overrun count.
2010	*/
2011	BUG_ON(q->info.si_code != SI_TIMER);
2012	q->info.si_overrun++;
2013	result = TRACE_SIGNAL_ALREADY_PENDING;
2014	goto out;
2015	}
2016	q->info.si_overrun = 0;
2017
2018	signalfd_notify(tsk: t, sig);
2019	pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
2020	list_add_tail(new: &q->list, head: &pending->list);
2021	sigaddset(set: &pending->signal, sig: sig);
2022	complete_signal(sig, p: t, type);
2023	result = TRACE_SIGNAL_DELIVERED;
2024	out:
2025	trace_signal_generate(sig, info: &q->info, task: t, group: type != PIDTYPE_PID, result);
2026	unlock_task_sighand(task: t, flags: &flags);
2027	ret:
2028	rcu_read_unlock();
2029	return ret;
2030	}
2031
2032	void do_notify_pidfd(struct task_struct *task)
2033	{
2034	struct pid *pid = task_pid(task);
2035
2036	WARN_ON(task->exit_state == 0);
2037
2038	__wake_up(wq_head: &pid->wait_pidfd, TASK_NORMAL, nr: 0,
2039	poll_to_key(EPOLLIN | EPOLLRDNORM));
2040	}
2041
2042	/*
2043	* Let a parent know about the death of a child.
2044	* For a stopped/continued status change, use do_notify_parent_cldstop instead.
2045	*
2046	* Returns true if our parent ignored us and so we've switched to
2047	* self-reaping.
2048	*/
2049	bool do_notify_parent(struct task_struct *tsk, int sig)
2050	{
2051	struct kernel_siginfo info;
2052	unsigned long flags;
2053	struct sighand_struct *psig;
2054	bool autoreap = false;
2055	u64 utime, stime;
2056
2057	WARN_ON_ONCE(sig == -1);
2058
2059	/* do_notify_parent_cldstop should have been called instead. */
2060	WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2061
2062	WARN_ON_ONCE(!tsk->ptrace &&
2063	(tsk->group_leader != tsk || !thread_group_empty(tsk)));
2064	/*
2065	* tsk is a group leader and has no threads, wake up the
2066	* non-PIDFD_THREAD waiters.
2067	*/
2068	if (thread_group_empty(p: tsk))
2069	do_notify_pidfd(task: tsk);
2070
2071	if (sig != SIGCHLD) {
2072	/*
2073	* This is only possible if parent == real_parent.
2074	* Check if it has changed security domain.
2075	*/
2076	if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2077	sig = SIGCHLD;
2078	}
2079
2080	clear_siginfo(info: &info);
2081	info.si_signo = sig;
2082	info.si_errno = 0;
2083	/*
2084	* We are under tasklist_lock here so our parent is tied to
2085	* us and cannot change.
2086	*
2087	* task_active_pid_ns will always return the same pid namespace
2088	* until a task passes through release_task.
2089	*
2090	* write_lock() currently calls preempt_disable() which is the
2091	* same as rcu_read_lock(), but according to Oleg, this is not
2092	* correct to rely on this
2093	*/
2094	rcu_read_lock();
2095	info.si_pid = task_pid_nr_ns(tsk, ns: task_active_pid_ns(tsk: tsk->parent));
2096	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2097	task_uid(tsk));
2098	rcu_read_unlock();
2099
2100	task_cputime(t: tsk, utime: &utime, stime: &stime);
2101	info.si_utime = nsec_to_clock_t(x: utime + tsk->signal->utime);
2102	info.si_stime = nsec_to_clock_t(x: stime + tsk->signal->stime);
2103
2104	info.si_status = tsk->exit_code & 0x7f;
2105	if (tsk->exit_code & 0x80)
2106	info.si_code = CLD_DUMPED;
2107	else if (tsk->exit_code & 0x7f)
2108	info.si_code = CLD_KILLED;
2109	else {
2110	info.si_code = CLD_EXITED;
2111	info.si_status = tsk->exit_code >> 8;
2112	}
2113
2114	psig = tsk->parent->sighand;
2115	spin_lock_irqsave(&psig->siglock, flags);
2116	if (!tsk->ptrace && sig == SIGCHLD &&
2117	(psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2118	(psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2119	/*
2120	* We are exiting and our parent doesn't care. POSIX.1
2121	* defines special semantics for setting SIGCHLD to SIG_IGN
2122	* or setting the SA_NOCLDWAIT flag: we should be reaped
2123	* automatically and not left for our parent's wait4 call.
2124	* Rather than having the parent do it as a magic kind of
2125	* signal handler, we just set this to tell do_exit that we
2126	* can be cleaned up without becoming a zombie. Note that
2127	* we still call __wake_up_parent in this case, because a
2128	* blocked sys_wait4 might now return -ECHILD.
2129	*
2130	* Whether we send SIGCHLD or not for SA_NOCLDWAIT
2131	* is implementation-defined: we do (if you don't want
2132	* it, just use SIG_IGN instead).
2133	*/
2134	autoreap = true;
2135	if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2136	sig = 0;
2137	}
2138	/*
2139	* Send with __send_signal as si_pid and si_uid are in the
2140	* parent's namespaces.
2141	*/
2142	if (valid_signal(sig) && sig)
2143	__send_signal_locked(sig, info: &info, t: tsk->parent, type: PIDTYPE_TGID, force: false);
2144	__wake_up_parent(p: tsk, parent: tsk->parent);
2145	spin_unlock_irqrestore(lock: &psig->siglock, flags);
2146
2147	return autoreap;
2148	}
2149
2150	/**
2151	* do_notify_parent_cldstop - notify parent of stopped/continued state change
2152	* @tsk: task reporting the state change
2153	* @for_ptracer: the notification is for ptracer
2154	* @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2155	*
2156	* Notify @tsk's parent that the stopped/continued state has changed. If
2157	* @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2158	* If %true, @tsk reports to @tsk->parent which should be the ptracer.
2159	*
2160	* CONTEXT:
2161	* Must be called with tasklist_lock at least read locked.
2162	*/
2163	static void do_notify_parent_cldstop(struct task_struct *tsk,
2164	bool for_ptracer, int why)
2165	{
2166	struct kernel_siginfo info;
2167	unsigned long flags;
2168	struct task_struct *parent;
2169	struct sighand_struct *sighand;
2170	u64 utime, stime;
2171
2172	if (for_ptracer) {
2173	parent = tsk->parent;
2174	} else {
2175	tsk = tsk->group_leader;
2176	parent = tsk->real_parent;
2177	}
2178
2179	clear_siginfo(info: &info);
2180	info.si_signo = SIGCHLD;
2181	info.si_errno = 0;
2182	/*
2183	* see comment in do_notify_parent() about the following 4 lines
2184	*/
2185	rcu_read_lock();
2186	info.si_pid = task_pid_nr_ns(tsk, ns: task_active_pid_ns(tsk: parent));
2187	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2188	rcu_read_unlock();
2189
2190	task_cputime(t: tsk, utime: &utime, stime: &stime);
2191	info.si_utime = nsec_to_clock_t(x: utime);
2192	info.si_stime = nsec_to_clock_t(x: stime);
2193
2194	info.si_code = why;
2195	switch (why) {
2196	case CLD_CONTINUED:
2197	info.si_status = SIGCONT;
2198	break;
2199	case CLD_STOPPED:
2200	info.si_status = tsk->signal->group_exit_code & 0x7f;
2201	break;
2202	case CLD_TRAPPED:
2203	info.si_status = tsk->exit_code & 0x7f;
2204	break;
2205	default:
2206	BUG();
2207	}
2208
2209	sighand = parent->sighand;
2210	spin_lock_irqsave(&sighand->siglock, flags);
2211	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2212	!(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2213	send_signal_locked(SIGCHLD, info: &info, t: parent, type: PIDTYPE_TGID);
2214	/*
2215	* Even if SIGCHLD is not generated, we must wake up wait4 calls.
2216	*/
2217	__wake_up_parent(p: tsk, parent);
2218	spin_unlock_irqrestore(lock: &sighand->siglock, flags);
2219	}
2220
2221	/*
2222	* This must be called with current->sighand->siglock held.
2223	*
2224	* This should be the path for all ptrace stops.
2225	* We always set current->last_siginfo while stopped here.
2226	* That makes it a way to test a stopped process for
2227	* being ptrace-stopped vs being job-control-stopped.
2228	*
2229	* Returns the signal the ptracer requested the code resume
2230	* with. If the code did not stop because the tracer is gone,
2231	* the stop signal remains unchanged unless clear_code.
2232	*/
2233	static int ptrace_stop(int exit_code, int why, unsigned long message,
2234	kernel_siginfo_t *info)
2235	__releases(&current->sighand->siglock)
2236	__acquires(&current->sighand->siglock)
2237	{
2238	bool gstop_done = false;
2239
2240	if (arch_ptrace_stop_needed()) {
2241	/*
2242	* The arch code has something special to do before a
2243	* ptrace stop. This is allowed to block, e.g. for faults
2244	* on user stack pages. We can't keep the siglock while
2245	* calling arch_ptrace_stop, so we must release it now.
2246	* To preserve proper semantics, we must do this before
2247	* any signal bookkeeping like checking group_stop_count.
2248	*/
2249	spin_unlock_irq(lock: &current->sighand->siglock);
2250	arch_ptrace_stop();
2251	spin_lock_irq(lock: &current->sighand->siglock);
2252	}
2253
2254	/*
2255	* After this point ptrace_signal_wake_up or signal_wake_up
2256	* will clear TASK_TRACED if ptrace_unlink happens or a fatal
2257	* signal comes in. Handle previous ptrace_unlinks and fatal
2258	* signals here to prevent ptrace_stop sleeping in schedule.
2259	*/
2260	if (!current->ptrace || __fatal_signal_pending(current))
2261	return exit_code;
2262
2263	set_special_state(TASK_TRACED);
2264	current->jobctl |= JOBCTL_TRACED;
2265
2266	/*
2267	* We're committing to trapping. TRACED should be visible before
2268	* TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2269	* Also, transition to TRACED and updates to ->jobctl should be
2270	* atomic with respect to siglock and should be done after the arch
2271	* hook as siglock is released and regrabbed across it.
2272	*
2273	* TRACER TRACEE
2274	*
2275	* ptrace_attach()
2276	* [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2277	* do_wait()
2278	* set_current_state() smp_wmb();
2279	* ptrace_do_wait()
2280	* wait_task_stopped()
2281	* task_stopped_code()
2282	* [L] task_is_traced() [S] task_clear_jobctl_trapping();
2283	*/
2284	smp_wmb();
2285
2286	current->ptrace_message = message;
2287	current->last_siginfo = info;
2288	current->exit_code = exit_code;
2289
2290	/*
2291	* If @why is CLD_STOPPED, we're trapping to participate in a group
2292	* stop. Do the bookkeeping. Note that if SIGCONT was delievered
2293	* across siglock relocks since INTERRUPT was scheduled, PENDING
2294	* could be clear now. We act as if SIGCONT is received after
2295	* TASK_TRACED is entered - ignore it.
2296	*/
2297	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2298	gstop_done = task_participate_group_stop(current);
2299
2300	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2301	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2302	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2303	task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2304
2305	/* entering a trap, clear TRAPPING */
2306	task_clear_jobctl_trapping(current);
2307
2308	spin_unlock_irq(lock: &current->sighand->siglock);
2309	read_lock(&tasklist_lock);
2310	/*
2311	* Notify parents of the stop.
2312	*
2313	* While ptraced, there are two parents - the ptracer and
2314	* the real_parent of the group_leader. The ptracer should
2315	* know about every stop while the real parent is only
2316	* interested in the completion of group stop. The states
2317	* for the two don't interact with each other. Notify
2318	* separately unless they're gonna be duplicates.
2319	*/
2320	if (current->ptrace)
2321	do_notify_parent_cldstop(current, for_ptracer: true, why);
2322	if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2323	do_notify_parent_cldstop(current, for_ptracer: false, why);
2324
2325	/*
2326	* The previous do_notify_parent_cldstop() invocation woke ptracer.
2327	* One a PREEMPTION kernel this can result in preemption requirement
2328	* which will be fulfilled after read_unlock() and the ptracer will be
2329	* put on the CPU.
2330	* The ptracer is in wait_task_inactive(, __TASK_TRACED) waiting for
2331	* this task wait in schedule(). If this task gets preempted then it
2332	* remains enqueued on the runqueue. The ptracer will observe this and
2333	* then sleep for a delay of one HZ tick. In the meantime this task
2334	* gets scheduled, enters schedule() and will wait for the ptracer.
2335	*
2336	* This preemption point is not bad from a correctness point of
2337	* view but extends the runtime by one HZ tick time due to the
2338	* ptracer's sleep. The preempt-disable section ensures that there
2339	* will be no preemption between unlock and schedule() and so
2340	* improving the performance since the ptracer will observe that
2341	* the tracee is scheduled out once it gets on the CPU.
2342	*
2343	* On PREEMPT_RT locking tasklist_lock does not disable preemption.
2344	* Therefore the task can be preempted after do_notify_parent_cldstop()
2345	* before unlocking tasklist_lock so there is no benefit in doing this.
2346	*
2347	* In fact disabling preemption is harmful on PREEMPT_RT because
2348	* the spinlock_t in cgroup_enter_frozen() must not be acquired
2349	* with preemption disabled due to the 'sleeping' spinlock
2350	* substitution of RT.
2351	*/
2352	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2353	preempt_disable();
2354	read_unlock(&tasklist_lock);
2355	cgroup_enter_frozen();
2356	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2357	preempt_enable_no_resched();
2358	schedule();
2359	cgroup_leave_frozen(always_leave: true);
2360
2361	/*
2362	* We are back. Now reacquire the siglock before touching
2363	* last_siginfo, so that we are sure to have synchronized with
2364	* any signal-sending on another CPU that wants to examine it.
2365	*/
2366	spin_lock_irq(lock: &current->sighand->siglock);
2367	exit_code = current->exit_code;
2368	current->last_siginfo = NULL;
2369	current->ptrace_message = 0;
2370	current->exit_code = 0;
2371
2372	/* LISTENING can be set only during STOP traps, clear it */
2373	current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2374
2375	/*
2376	* Queued signals ignored us while we were stopped for tracing.
2377	* So check for any that we should take before resuming user mode.
2378	* This sets TIF_SIGPENDING, but never clears it.
2379	*/
2380	recalc_sigpending_tsk(current);
2381	return exit_code;
2382	}
2383
2384	static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2385	{
2386	kernel_siginfo_t info;
2387
2388	clear_siginfo(info: &info);
2389	info.si_signo = signr;
2390	info.si_code = exit_code;
2391	info.si_pid = task_pid_vnr(current);
2392	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2393
2394	/* Let the debugger run. */
2395	return ptrace_stop(exit_code, why, message, info: &info);
2396	}
2397
2398	int ptrace_notify(int exit_code, unsigned long message)
2399	{
2400	int signr;
2401
2402	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2403	if (unlikely(task_work_pending(current)))
2404	task_work_run();
2405
2406	spin_lock_irq(lock: &current->sighand->siglock);
2407	signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2408	spin_unlock_irq(lock: &current->sighand->siglock);
2409	return signr;
2410	}
2411
2412	/**
2413	* do_signal_stop - handle group stop for SIGSTOP and other stop signals
2414	* @signr: signr causing group stop if initiating
2415	*
2416	* If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2417	* and participate in it. If already set, participate in the existing
2418	* group stop. If participated in a group stop (and thus slept), %true is
2419	* returned with siglock released.
2420	*
2421	* If ptraced, this function doesn't handle stop itself. Instead,
2422	* %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2423	* untouched. The caller must ensure that INTERRUPT trap handling takes
2424	* places afterwards.
2425	*
2426	* CONTEXT:
2427	* Must be called with @current->sighand->siglock held, which is released
2428	* on %true return.
2429	*
2430	* RETURNS:
2431	* %false if group stop is already cancelled or ptrace trap is scheduled.
2432	* %true if participated in group stop.
2433	*/
2434	static bool do_signal_stop(int signr)
2435	__releases(&current->sighand->siglock)
2436	{
2437	struct signal_struct *sig = current->signal;
2438
2439	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2440	unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2441	struct task_struct *t;
2442
2443	/* signr will be recorded in task->jobctl for retries */
2444	WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2445
2446	if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2447	unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2448	unlikely(sig->group_exec_task))
2449	return false;
2450	/*
2451	* There is no group stop already in progress. We must
2452	* initiate one now.
2453	*
2454	* While ptraced, a task may be resumed while group stop is
2455	* still in effect and then receive a stop signal and
2456	* initiate another group stop. This deviates from the
2457	* usual behavior as two consecutive stop signals can't
2458	* cause two group stops when !ptraced. That is why we
2459	* also check !task_is_stopped(t) below.
2460	*
2461	* The condition can be distinguished by testing whether
2462	* SIGNAL_STOP_STOPPED is already set. Don't generate
2463	* group_exit_code in such case.
2464	*
2465	* This is not necessary for SIGNAL_STOP_CONTINUED because
2466	* an intervening stop signal is required to cause two
2467	* continued events regardless of ptrace.
2468	*/
2469	if (!(sig->flags & SIGNAL_STOP_STOPPED))
2470	sig->group_exit_code = signr;
2471
2472	sig->group_stop_count = 0;
2473	if (task_set_jobctl_pending(current, mask: signr | gstop))
2474	sig->group_stop_count++;
2475
2476	for_other_threads(current, t) {
2477	/*
2478	* Setting state to TASK_STOPPED for a group
2479	* stop is always done with the siglock held,
2480	* so this check has no races.
2481	*/
2482	if (!task_is_stopped(t) &&
2483	task_set_jobctl_pending(task: t, mask: signr | gstop)) {
2484	sig->group_stop_count++;
2485	if (likely(!(t->ptrace & PT_SEIZED)))
2486	signal_wake_up(t, fatal: 0);
2487	else
2488	ptrace_trap_notify(t);
2489	}
2490	}
2491	}
2492
2493	if (likely(!current->ptrace)) {
2494	int notify = 0;
2495
2496	/*
2497	* If there are no other threads in the group, or if there
2498	* is a group stop in progress and we are the last to stop,
2499	* report to the parent.
2500	*/
2501	if (task_participate_group_stop(current))
2502	notify = CLD_STOPPED;
2503
2504	current->jobctl |= JOBCTL_STOPPED;
2505	set_special_state(TASK_STOPPED);
2506	spin_unlock_irq(lock: &current->sighand->siglock);
2507
2508	/*
2509	* Notify the parent of the group stop completion. Because
2510	* we're not holding either the siglock or tasklist_lock
2511	* here, ptracer may attach inbetween; however, this is for
2512	* group stop and should always be delivered to the real
2513	* parent of the group leader. The new ptracer will get
2514	* its notification when this task transitions into
2515	* TASK_TRACED.
2516	*/
2517	if (notify) {
2518	read_lock(&tasklist_lock);
2519	do_notify_parent_cldstop(current, for_ptracer: false, why: notify);
2520	read_unlock(&tasklist_lock);
2521	}
2522
2523	/* Now we don't run again until woken by SIGCONT or SIGKILL */
2524	cgroup_enter_frozen();
2525	schedule();
2526	return true;
2527	} else {
2528	/*
2529	* While ptraced, group stop is handled by STOP trap.
2530	* Schedule it and let the caller deal with it.
2531	*/
2532	task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2533	return false;
2534	}
2535	}
2536
2537	/**
2538	* do_jobctl_trap - take care of ptrace jobctl traps
2539	*
2540	* When PT_SEIZED, it's used for both group stop and explicit
2541	* SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2542	* accompanying siginfo. If stopped, lower eight bits of exit_code contain
2543	* the stop signal; otherwise, %SIGTRAP.
2544	*
2545	* When !PT_SEIZED, it's used only for group stop trap with stop signal
2546	* number as exit_code and no siginfo.
2547	*
2548	* CONTEXT:
2549	* Must be called with @current->sighand->siglock held, which may be
2550	* released and re-acquired before returning with intervening sleep.
2551	*/
2552	static void do_jobctl_trap(void)
2553	{
2554	struct signal_struct *signal = current->signal;
2555	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2556
2557	if (current->ptrace & PT_SEIZED) {
2558	if (!signal->group_stop_count &&
2559	!(signal->flags & SIGNAL_STOP_STOPPED))
2560	signr = SIGTRAP;
2561	WARN_ON_ONCE(!signr);
2562	ptrace_do_notify(signr, exit_code: signr | (PTRACE_EVENT_STOP << 8),
2563	CLD_STOPPED, message: 0);
2564	} else {
2565	WARN_ON_ONCE(!signr);
2566	ptrace_stop(exit_code: signr, CLD_STOPPED, message: 0, NULL);
2567	}
2568	}
2569
2570	/**
2571	* do_freezer_trap - handle the freezer jobctl trap
2572	*
2573	* Puts the task into frozen state, if only the task is not about to quit.
2574	* In this case it drops JOBCTL_TRAP_FREEZE.
2575	*
2576	* CONTEXT:
2577	* Must be called with @current->sighand->siglock held,
2578	* which is always released before returning.
2579	*/
2580	static void do_freezer_trap(void)
2581	__releases(&current->sighand->siglock)
2582	{
2583	/*
2584	* If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2585	* let's make another loop to give it a chance to be handled.
2586	* In any case, we'll return back.
2587	*/
2588	if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2589	JOBCTL_TRAP_FREEZE) {
2590	spin_unlock_irq(lock: &current->sighand->siglock);
2591	return;
2592	}
2593
2594	/*
2595	* Now we're sure that there is no pending fatal signal and no
2596	* pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2597	* immediately (if there is a non-fatal signal pending), and
2598	* put the task into sleep.
2599	*/
2600	__set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2601	clear_thread_flag(TIF_SIGPENDING);
2602	spin_unlock_irq(lock: &current->sighand->siglock);
2603	cgroup_enter_frozen();
2604	schedule();
2605	}
2606
2607	static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2608	{
2609	/*
2610	* We do not check sig_kernel_stop(signr) but set this marker
2611	* unconditionally because we do not know whether debugger will
2612	* change signr. This flag has no meaning unless we are going
2613	* to stop after return from ptrace_stop(). In this case it will
2614	* be checked in do_signal_stop(), we should only stop if it was
2615	* not cleared by SIGCONT while we were sleeping. See also the
2616	* comment in dequeue_signal().
2617	*/
2618	current->jobctl |= JOBCTL_STOP_DEQUEUED;
2619	signr = ptrace_stop(exit_code: signr, CLD_TRAPPED, message: 0, info);
2620
2621	/* We're back. Did the debugger cancel the sig? */
2622	if (signr == 0)
2623	return signr;
2624
2625	/*
2626	* Update the siginfo structure if the signal has
2627	* changed. If the debugger wanted something
2628	* specific in the siginfo structure then it should
2629	* have updated *info via PTRACE_SETSIGINFO.
2630	*/
2631	if (signr != info->si_signo) {
2632	clear_siginfo(info);
2633	info->si_signo = signr;
2634	info->si_errno = 0;
2635	info->si_code = SI_USER;
2636	rcu_read_lock();
2637	info->si_pid = task_pid_vnr(current->parent);
2638	info->si_uid = from_kuid_munged(current_user_ns(),
2639	task_uid(current->parent));
2640	rcu_read_unlock();
2641	}
2642
2643	/* If the (new) signal is now blocked, requeue it. */
2644	if (sigismember(set: &current->blocked, sig: signr) ||
2645	fatal_signal_pending(current)) {
2646	send_signal_locked(sig: signr, info, current, type);
2647	signr = 0;
2648	}
2649
2650	return signr;
2651	}
2652
2653	static void hide_si_addr_tag_bits(struct ksignal *ksig)
2654	{
2655	switch (siginfo_layout(sig: ksig->sig, si_code: ksig->info.si_code)) {
2656	case SIL_FAULT:
2657	case SIL_FAULT_TRAPNO:
2658	case SIL_FAULT_MCEERR:
2659	case SIL_FAULT_BNDERR:
2660	case SIL_FAULT_PKUERR:
2661	case SIL_FAULT_PERF_EVENT:
2662	ksig->info.si_addr = arch_untagged_si_addr(
2663	addr: ksig->info.si_addr, sig: ksig->sig, si_code: ksig->info.si_code);
2664	break;
2665	case SIL_KILL:
2666	case SIL_TIMER:
2667	case SIL_POLL:
2668	case SIL_CHLD:
2669	case SIL_RT:
2670	case SIL_SYS:
2671	break;
2672	}
2673	}
2674
2675	bool get_signal(struct ksignal *ksig)
2676	{
2677	struct sighand_struct *sighand = current->sighand;
2678	struct signal_struct *signal = current->signal;
2679	int signr;
2680
2681	clear_notify_signal();
2682	if (unlikely(task_work_pending(current)))
2683	task_work_run();
2684
2685	if (!task_sigpending(current))
2686	return false;
2687
2688	if (unlikely(uprobe_deny_signal()))
2689	return false;
2690
2691	/*
2692	* Do this once, we can't return to user-mode if freezing() == T.
2693	* do_signal_stop() and ptrace_stop() do freezable_schedule() and
2694	* thus do not need another check after return.
2695	*/
2696	try_to_freeze();
2697
2698	relock:
2699	spin_lock_irq(lock: &sighand->siglock);
2700
2701	/*
2702	* Every stopped thread goes here after wakeup. Check to see if
2703	* we should notify the parent, prepare_signal(SIGCONT) encodes
2704	* the CLD_ si_code into SIGNAL_CLD_MASK bits.
2705	*/
2706	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2707	int why;
2708
2709	if (signal->flags & SIGNAL_CLD_CONTINUED)
2710	why = CLD_CONTINUED;
2711	else
2712	why = CLD_STOPPED;
2713
2714	signal->flags &= ~SIGNAL_CLD_MASK;
2715
2716	spin_unlock_irq(lock: &sighand->siglock);
2717
2718	/*
2719	* Notify the parent that we're continuing. This event is
2720	* always per-process and doesn't make whole lot of sense
2721	* for ptracers, who shouldn't consume the state via
2722	* wait(2) either, but, for backward compatibility, notify
2723	* the ptracer of the group leader too unless it's gonna be
2724	* a duplicate.
2725	*/
2726	read_lock(&tasklist_lock);
2727	do_notify_parent_cldstop(current, for_ptracer: false, why);
2728
2729	if (ptrace_reparented(current->group_leader))
2730	do_notify_parent_cldstop(current->group_leader,
2731	for_ptracer: true, why);
2732	read_unlock(&tasklist_lock);
2733
2734	goto relock;
2735	}
2736
2737	for (;;) {
2738	struct k_sigaction *ka;
2739	enum pid_type type;
2740
2741	/* Has this task already been marked for death? */
2742	if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2743	signal->group_exec_task) {
2744	signr = SIGKILL;
2745	sigdelset(set: &current->pending.signal, SIGKILL);
2746	trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2747	ka: &sighand->action[SIGKILL-1]);
2748	recalc_sigpending();
2749	/*
2750	* implies do_group_exit() or return to PF_USER_WORKER,
2751	* no need to initialize ksig->info/etc.
2752	*/
2753	goto fatal;
2754	}
2755
2756	if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2757	do_signal_stop(signr: 0))
2758	goto relock;
2759
2760	if (unlikely(current->jobctl &
2761	(JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2762	if (current->jobctl & JOBCTL_TRAP_MASK) {
2763	do_jobctl_trap();
2764	spin_unlock_irq(lock: &sighand->siglock);
2765	} else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2766	do_freezer_trap();
2767
2768	goto relock;
2769	}
2770
2771	/*
2772	* If the task is leaving the frozen state, let's update
2773	* cgroup counters and reset the frozen bit.
2774	*/
2775	if (unlikely(cgroup_task_frozen(current))) {
2776	spin_unlock_irq(lock: &sighand->siglock);
2777	cgroup_leave_frozen(always_leave: false);
2778	goto relock;
2779	}
2780
2781	/*
2782	* Signals generated by the execution of an instruction
2783	* need to be delivered before any other pending signals
2784	* so that the instruction pointer in the signal stack
2785	* frame points to the faulting instruction.
2786	*/
2787	type = PIDTYPE_PID;
2788	signr = dequeue_synchronous_signal(info: &ksig->info);
2789	if (!signr)
2790	signr = dequeue_signal(current, &current->blocked,
2791	&ksig->info, &type);
2792
2793	if (!signr)
2794	break; /* will return 0 */
2795
2796	if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2797	!(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2798	signr = ptrace_signal(signr, info: &ksig->info, type);
2799	if (!signr)
2800	continue;
2801	}
2802
2803	ka = &sighand->action[signr-1];
2804
2805	/* Trace actually delivered signals. */
2806	trace_signal_deliver(sig: signr, info: &ksig->info, ka);
2807
2808	if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2809	continue;
2810	if (ka->sa.sa_handler != SIG_DFL) {
2811	/* Run the handler. */
2812	ksig->ka = *ka;
2813
2814	if (ka->sa.sa_flags & SA_ONESHOT)
2815	ka->sa.sa_handler = SIG_DFL;
2816
2817	break; /* will return non-zero "signr" value */
2818	}
2819
2820	/*
2821	* Now we are doing the default action for this signal.
2822	*/
2823	if (sig_kernel_ignore(signr)) /* Default is nothing. */
2824	continue;
2825
2826	/*
2827	* Global init gets no signals it doesn't want.
2828	* Container-init gets no signals it doesn't want from same
2829	* container.
2830	*
2831	* Note that if global/container-init sees a sig_kernel_only()
2832	* signal here, the signal must have been generated internally
2833	* or must have come from an ancestor namespace. In either
2834	* case, the signal cannot be dropped.
2835	*/
2836	if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2837	!sig_kernel_only(signr))
2838	continue;
2839
2840	if (sig_kernel_stop(signr)) {
2841	/*
2842	* The default action is to stop all threads in
2843	* the thread group. The job control signals
2844	* do nothing in an orphaned pgrp, but SIGSTOP
2845	* always works. Note that siglock needs to be
2846	* dropped during the call to is_orphaned_pgrp()
2847	* because of lock ordering with tasklist_lock.
2848	* This allows an intervening SIGCONT to be posted.
2849	* We need to check for that and bail out if necessary.
2850	*/
2851	if (signr != SIGSTOP) {
2852	spin_unlock_irq(lock: &sighand->siglock);
2853
2854	/* signals can be posted during this window */
2855
2856	if (is_current_pgrp_orphaned())
2857	goto relock;
2858
2859	spin_lock_irq(lock: &sighand->siglock);
2860	}
2861
2862	if (likely(do_signal_stop(signr))) {
2863	/* It released the siglock. */
2864	goto relock;
2865	}
2866
2867	/*
2868	* We didn't actually stop, due to a race
2869	* with SIGCONT or something like that.
2870	*/
2871	continue;
2872	}
2873
2874	fatal:
2875	spin_unlock_irq(lock: &sighand->siglock);
2876	if (unlikely(cgroup_task_frozen(current)))
2877	cgroup_leave_frozen(always_leave: true);
2878
2879	/*
2880	* Anything else is fatal, maybe with a core dump.
2881	*/
2882	current->flags |= PF_SIGNALED;
2883
2884	if (sig_kernel_coredump(signr)) {
2885	if (print_fatal_signals)
2886	print_fatal_signal(signr);
2887	proc_coredump_connector(current);
2888	/*
2889	* If it was able to dump core, this kills all
2890	* other threads in the group and synchronizes with
2891	* their demise. If we lost the race with another
2892	* thread getting here, it set group_exit_code
2893	* first and our do_group_exit call below will use
2894	* that value and ignore the one we pass it.
2895	*/
2896	do_coredump(siginfo: &ksig->info);
2897	}
2898
2899	/*
2900	* PF_USER_WORKER threads will catch and exit on fatal signals
2901	* themselves. They have cleanup that must be performed, so we
2902	* cannot call do_exit() on their behalf. Note that ksig won't
2903	* be properly initialized, PF_USER_WORKER's shouldn't use it.
2904	*/
2905	if (current->flags & PF_USER_WORKER)
2906	goto out;
2907
2908	/*
2909	* Death signals, no core dump.
2910	*/
2911	do_group_exit(signr);
2912	/* NOTREACHED */
2913	}
2914	spin_unlock_irq(lock: &sighand->siglock);
2915
2916	ksig->sig = signr;
2917
2918	if (signr && !(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2919	hide_si_addr_tag_bits(ksig);
2920	out:
2921	return signr > 0;
2922	}
2923
2924	/**
2925	* signal_delivered - called after signal delivery to update blocked signals
2926	* @ksig: kernel signal struct
2927	* @stepping: nonzero if debugger single-step or block-step in use
2928	*
2929	* This function should be called when a signal has successfully been
2930	* delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2931	* is always blocked), and the signal itself is blocked unless %SA_NODEFER
2932	* is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2933	*/
2934	static void signal_delivered(struct ksignal *ksig, int stepping)
2935	{
2936	sigset_t blocked;
2937
2938	/* A signal was successfully delivered, and the
2939	saved sigmask was stored on the signal frame,
2940	and will be restored by sigreturn. So we can
2941	simply clear the restore sigmask flag. */
2942	clear_restore_sigmask();
2943
2944	sigorsets(r: &blocked, a: &current->blocked, b: &ksig->ka.sa.sa_mask);
2945	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2946	sigaddset(set: &blocked, sig: ksig->sig);
2947	set_current_blocked(&blocked);
2948	if (current->sas_ss_flags & SS_AUTODISARM)
2949	sas_ss_reset(current);
2950	if (stepping)
2951	ptrace_notify(SIGTRAP, message: 0);
2952	}
2953
2954	void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2955	{
2956	if (failed)
2957	force_sigsegv(sig: ksig->sig);
2958	else
2959	signal_delivered(ksig, stepping);
2960	}
2961
2962	/*
2963	* It could be that complete_signal() picked us to notify about the
2964	* group-wide signal. Other threads should be notified now to take
2965	* the shared signals in @which since we will not.
2966	*/
2967	static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2968	{
2969	sigset_t retarget;
2970	struct task_struct *t;
2971
2972	sigandsets(r: &retarget, a: &tsk->signal->shared_pending.signal, b: which);
2973	if (sigisemptyset(set: &retarget))
2974	return;
2975
2976	for_other_threads(tsk, t) {
2977	if (t->flags & PF_EXITING)
2978	continue;
2979
2980	if (!has_pending_signals(signal: &retarget, blocked: &t->blocked))
2981	continue;
2982	/* Remove the signals this thread can handle. */
2983	sigandsets(r: &retarget, a: &retarget, b: &t->blocked);
2984
2985	if (!task_sigpending(p: t))
2986	signal_wake_up(t, fatal: 0);
2987
2988	if (sigisemptyset(set: &retarget))
2989	break;
2990	}
2991	}
2992
2993	void exit_signals(struct task_struct *tsk)
2994	{
2995	int group_stop = 0;
2996	sigset_t unblocked;
2997
2998	/*
2999	* @tsk is about to have PF_EXITING set - lock out users which
3000	* expect stable threadgroup.
3001	*/
3002	cgroup_threadgroup_change_begin(tsk);
3003
3004	if (thread_group_empty(p: tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
3005	sched_mm_cid_exit_signals(t: tsk);
3006	tsk->flags |= PF_EXITING;
3007	cgroup_threadgroup_change_end(tsk);
3008	return;
3009	}
3010
3011	spin_lock_irq(lock: &tsk->sighand->siglock);
3012	/*
3013	* From now this task is not visible for group-wide signals,
3014	* see wants_signal(), do_signal_stop().
3015	*/
3016	sched_mm_cid_exit_signals(t: tsk);
3017	tsk->flags |= PF_EXITING;
3018
3019	cgroup_threadgroup_change_end(tsk);
3020
3021	if (!task_sigpending(p: tsk))
3022	goto out;
3023
3024	unblocked = tsk->blocked;
3025	signotset(set: &unblocked);
3026	retarget_shared_pending(tsk, which: &unblocked);
3027
3028	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3029	task_participate_group_stop(task: tsk))
3030	group_stop = CLD_STOPPED;
3031	out:
3032	spin_unlock_irq(lock: &tsk->sighand->siglock);
3033
3034	/*
3035	* If group stop has completed, deliver the notification. This
3036	* should always go to the real parent of the group leader.
3037	*/
3038	if (unlikely(group_stop)) {
3039	read_lock(&tasklist_lock);
3040	do_notify_parent_cldstop(tsk, for_ptracer: false, why: group_stop);
3041	read_unlock(&tasklist_lock);
3042	}
3043	}
3044
3045	/*
3046	* System call entry points.
3047	*/
3048
3049	/**
3050	* sys_restart_syscall - restart a system call
3051	*/
3052	SYSCALL_DEFINE0(restart_syscall)
3053	{
3054	struct restart_block *restart = &current->restart_block;
3055	return restart->fn(restart);
3056	}
3057
3058	long do_no_restart_syscall(struct restart_block *param)
3059	{
3060	return -EINTR;
3061	}
3062
3063	static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3064	{
3065	if (task_sigpending(p: tsk) && !thread_group_empty(p: tsk)) {
3066	sigset_t newblocked;
3067	/* A set of now blocked but previously unblocked signals. */
3068	sigandnsets(r: &newblocked, a: newset, b: &current->blocked);
3069	retarget_shared_pending(tsk, which: &newblocked);
3070	}
3071	tsk->blocked = *newset;
3072	recalc_sigpending();
3073	}
3074
3075	/**
3076	* set_current_blocked - change current->blocked mask
3077	* @newset: new mask
3078	*
3079	* It is wrong to change ->blocked directly, this helper should be used
3080	* to ensure the process can't miss a shared signal we are going to block.
3081	*/
3082	void set_current_blocked(sigset_t *newset)
3083	{
3084	sigdelsetmask(set: newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3085	__set_current_blocked(newset);
3086	}
3087
3088	void __set_current_blocked(const sigset_t *newset)
3089	{
3090	struct task_struct *tsk = current;
3091
3092	/*
3093	* In case the signal mask hasn't changed, there is nothing we need
3094	* to do. The current->blocked shouldn't be modified by other task.
3095	*/
3096	if (sigequalsets(set1: &tsk->blocked, set2: newset))
3097	return;
3098
3099	spin_lock_irq(lock: &tsk->sighand->siglock);
3100	__set_task_blocked(tsk, newset);
3101	spin_unlock_irq(lock: &tsk->sighand->siglock);
3102	}
3103
3104	/*
3105	* This is also useful for kernel threads that want to temporarily
3106	* (or permanently) block certain signals.
3107	*
3108	* NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3109	* interface happily blocks "unblockable" signals like SIGKILL
3110	* and friends.
3111	*/
3112	int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3113	{
3114	struct task_struct *tsk = current;
3115	sigset_t newset;
3116
3117	/* Lockless, only current can change ->blocked, never from irq */
3118	if (oldset)
3119	*oldset = tsk->blocked;
3120
3121	switch (how) {
3122	case SIG_BLOCK:
3123	sigorsets(r: &newset, a: &tsk->blocked, b: set);
3124	break;
3125	case SIG_UNBLOCK:
3126	sigandnsets(r: &newset, a: &tsk->blocked, b: set);
3127	break;
3128	case SIG_SETMASK:
3129	newset = *set;
3130	break;
3131	default:
3132	return -EINVAL;
3133	}
3134
3135	__set_current_blocked(newset: &newset);
3136	return 0;
3137	}
3138	EXPORT_SYMBOL(sigprocmask);
3139
3140	/*
3141	* The api helps set app-provided sigmasks.
3142	*
3143	* This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3144	* epoll_pwait where a new sigmask is passed from userland for the syscalls.
3145	*
3146	* Note that it does set_restore_sigmask() in advance, so it must be always
3147	* paired with restore_saved_sigmask_unless() before return from syscall.
3148	*/
3149	int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3150	{
3151	sigset_t kmask;
3152
3153	if (!umask)
3154	return 0;
3155	if (sigsetsize != sizeof(sigset_t))
3156	return -EINVAL;
3157	if (copy_from_user(to: &kmask, from: umask, n: sizeof(sigset_t)))
3158	return -EFAULT;
3159
3160	set_restore_sigmask();
3161	current->saved_sigmask = current->blocked;
3162	set_current_blocked(&kmask);
3163
3164	return 0;
3165	}
3166
3167	#ifdef CONFIG_COMPAT
3168	int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3169	size_t sigsetsize)
3170	{
3171	sigset_t kmask;
3172
3173	if (!umask)
3174	return 0;
3175	if (sigsetsize != sizeof(compat_sigset_t))
3176	return -EINVAL;
3177	if (get_compat_sigset(set: &kmask, compat: umask))
3178	return -EFAULT;
3179
3180	set_restore_sigmask();
3181	current->saved_sigmask = current->blocked;
3182	set_current_blocked(&kmask);
3183
3184	return 0;
3185	}
3186	#endif
3187
3188	/**
3189	* sys_rt_sigprocmask - change the list of currently blocked signals
3190	* @how: whether to add, remove, or set signals
3191	* @nset: stores pending signals
3192	* @oset: previous value of signal mask if non-null
3193	* @sigsetsize: size of sigset_t type
3194	*/
3195	SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3196	sigset_t __user *, oset, size_t, sigsetsize)
3197	{
3198	sigset_t old_set, new_set;
3199	int error;
3200
3201	/* XXX: Don't preclude handling different sized sigset_t's. */
3202	if (sigsetsize != sizeof(sigset_t))
3203	return -EINVAL;
3204
3205	old_set = current->blocked;
3206
3207	if (nset) {
3208	if (copy_from_user(to: &new_set, from: nset, n: sizeof(sigset_t)))
3209	return -EFAULT;
3210	sigdelsetmask(set: &new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3211
3212	error = sigprocmask(how, &new_set, NULL);
3213	if (error)
3214	return error;
3215	}
3216
3217	if (oset) {
3218	if (copy_to_user(to: oset, from: &old_set, n: sizeof(sigset_t)))
3219	return -EFAULT;
3220	}
3221
3222	return 0;
3223	}
3224
3225	#ifdef CONFIG_COMPAT
3226	COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3227	compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3228	{
3229	sigset_t old_set = current->blocked;
3230
3231	/* XXX: Don't preclude handling different sized sigset_t's. */
3232	if (sigsetsize != sizeof(sigset_t))
3233	return -EINVAL;
3234
3235	if (nset) {
3236	sigset_t new_set;
3237	int error;
3238	if (get_compat_sigset(set: &new_set, compat: nset))
3239	return -EFAULT;
3240	sigdelsetmask(set: &new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3241
3242	error = sigprocmask(how, &new_set, NULL);
3243	if (error)
3244	return error;
3245	}
3246	return oset ? put_compat_sigset(compat: oset, set: &old_set, size: sizeof(*oset)) : 0;
3247	}
3248	#endif
3249
3250	static void do_sigpending(sigset_t *set)
3251	{
3252	spin_lock_irq(lock: &current->sighand->siglock);
3253	sigorsets(r: set, a: &current->pending.signal,
3254	b: &current->signal->shared_pending.signal);
3255	spin_unlock_irq(lock: &current->sighand->siglock);
3256
3257	/* Outside the lock because only this thread touches it. */
3258	sigandsets(r: set, a: &current->blocked, b: set);
3259	}
3260
3261	/**
3262	* sys_rt_sigpending - examine a pending signal that has been raised
3263	* while blocked
3264	* @uset: stores pending signals
3265	* @sigsetsize: size of sigset_t type or larger
3266	*/
3267	SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3268	{
3269	sigset_t set;
3270
3271	if (sigsetsize > sizeof(*uset))
3272	return -EINVAL;
3273
3274	do_sigpending(set: &set);
3275
3276	if (copy_to_user(to: uset, from: &set, n: sigsetsize))
3277	return -EFAULT;
3278
3279	return 0;
3280	}
3281
3282	#ifdef CONFIG_COMPAT
3283	COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3284	compat_size_t, sigsetsize)
3285	{
3286	sigset_t set;
3287
3288	if (sigsetsize > sizeof(*uset))
3289	return -EINVAL;
3290
3291	do_sigpending(set: &set);
3292
3293	return put_compat_sigset(compat: uset, set: &set, size: sigsetsize);
3294	}
3295	#endif
3296
3297	static const struct {
3298	unsigned char limit, layout;
3299	} sig_sicodes[] = {
3300	[SIGILL] = { NSIGILL, SIL_FAULT },
3301	[SIGFPE] = { NSIGFPE, SIL_FAULT },
3302	[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3303	[SIGBUS] = { NSIGBUS, SIL_FAULT },
3304	[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3305	#if defined(SIGEMT)
3306	[SIGEMT] = { NSIGEMT, SIL_FAULT },
3307	#endif
3308	[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3309	[SIGPOLL] = { NSIGPOLL, SIL_POLL },
3310	[SIGSYS] = { NSIGSYS, SIL_SYS },
3311	};
3312
3313	static bool known_siginfo_layout(unsigned sig, int si_code)
3314	{
3315	if (si_code == SI_KERNEL)
3316	return true;
3317	else if ((si_code > SI_USER)) {
3318	if (sig_specific_sicodes(sig)) {
3319	if (si_code <= sig_sicodes[sig].limit)
3320	return true;
3321	}
3322	else if (si_code <= NSIGPOLL)
3323	return true;
3324	}
3325	else if (si_code >= SI_DETHREAD)
3326	return true;
3327	else if (si_code == SI_ASYNCNL)
3328	return true;
3329	return false;
3330	}
3331
3332	enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3333	{
3334	enum siginfo_layout layout = SIL_KILL;
3335	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3336	if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3337	(si_code <= sig_sicodes[sig].limit)) {
3338	layout = sig_sicodes[sig].layout;
3339	/* Handle the exceptions */
3340	if ((sig == SIGBUS) &&
3341	(si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3342	layout = SIL_FAULT_MCEERR;
3343	else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3344	layout = SIL_FAULT_BNDERR;
3345	#ifdef SEGV_PKUERR
3346	else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3347	layout = SIL_FAULT_PKUERR;
3348	#endif
3349	else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3350	layout = SIL_FAULT_PERF_EVENT;
3351	else if (IS_ENABLED(CONFIG_SPARC) &&
3352	(sig == SIGILL) && (si_code == ILL_ILLTRP))
3353	layout = SIL_FAULT_TRAPNO;
3354	else if (IS_ENABLED(CONFIG_ALPHA) &&
3355	((sig == SIGFPE) ||
3356	((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3357	layout = SIL_FAULT_TRAPNO;
3358	}
3359	else if (si_code <= NSIGPOLL)
3360	layout = SIL_POLL;
3361	} else {
3362	if (si_code == SI_TIMER)
3363	layout = SIL_TIMER;
3364	else if (si_code == SI_SIGIO)
3365	layout = SIL_POLL;
3366	else if (si_code < 0)
3367	layout = SIL_RT;
3368	}
3369	return layout;
3370	}
3371
3372	static inline char __user *si_expansion(const siginfo_t __user *info)
3373	{
3374	return ((char __user *)info) + sizeof(struct kernel_siginfo);
3375	}
3376
3377	int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3378	{
3379	char __user *expansion = si_expansion(info: to);
3380	if (copy_to_user(to, from , n: sizeof(struct kernel_siginfo)))
3381	return -EFAULT;
3382	if (clear_user(to: expansion, SI_EXPANSION_SIZE))
3383	return -EFAULT;
3384	return 0;
3385	}
3386
3387	static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3388	const siginfo_t __user *from)
3389	{
3390	if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3391	char __user *expansion = si_expansion(info: from);
3392	char buf[SI_EXPANSION_SIZE];
3393	int i;
3394	/*
3395	* An unknown si_code might need more than
3396	* sizeof(struct kernel_siginfo) bytes. Verify all of the
3397	* extra bytes are 0. This guarantees copy_siginfo_to_user
3398	* will return this data to userspace exactly.
3399	*/
3400	if (copy_from_user(to: &buf, from: expansion, SI_EXPANSION_SIZE))
3401	return -EFAULT;
3402	for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3403	if (buf[i] != 0)
3404	return -E2BIG;
3405	}
3406	}
3407	return 0;
3408	}
3409
3410	static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3411	const siginfo_t __user *from)
3412	{
3413	if (copy_from_user(to, from, n: sizeof(struct kernel_siginfo)))
3414	return -EFAULT;
3415	to->si_signo = signo;
3416	return post_copy_siginfo_from_user(info: to, from);
3417	}
3418
3419	int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3420	{
3421	if (copy_from_user(to, from, n: sizeof(struct kernel_siginfo)))
3422	return -EFAULT;
3423	return post_copy_siginfo_from_user(info: to, from);
3424	}
3425
3426	#ifdef CONFIG_COMPAT
3427	/**
3428	* copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3429	* @to: compat siginfo destination
3430	* @from: kernel siginfo source
3431	*
3432	* Note: This function does not work properly for the SIGCHLD on x32, but
3433	* fortunately it doesn't have to. The only valid callers for this function are
3434	* copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3435	* The latter does not care because SIGCHLD will never cause a coredump.
3436	*/
3437	void copy_siginfo_to_external32(struct compat_siginfo *to,
3438	const struct kernel_siginfo *from)
3439	{
3440	memset(to, 0, sizeof(*to));
3441
3442	to->si_signo = from->si_signo;
3443	to->si_errno = from->si_errno;
3444	to->si_code = from->si_code;
3445	switch(siginfo_layout(sig: from->si_signo, si_code: from->si_code)) {
3446	case SIL_KILL:
3447	to->si_pid = from->si_pid;
3448	to->si_uid = from->si_uid;
3449	break;
3450	case SIL_TIMER:
3451	to->si_tid = from->si_tid;
3452	to->si_overrun = from->si_overrun;
3453	to->si_int = from->si_int;
3454	break;
3455	case SIL_POLL:
3456	to->si_band = from->si_band;
3457	to->si_fd = from->si_fd;
3458	break;
3459	case SIL_FAULT:
3460	to->si_addr = ptr_to_compat(uptr: from->si_addr);
3461	break;
3462	case SIL_FAULT_TRAPNO:
3463	to->si_addr = ptr_to_compat(uptr: from->si_addr);
3464	to->si_trapno = from->si_trapno;
3465	break;
3466	case SIL_FAULT_MCEERR:
3467	to->si_addr = ptr_to_compat(uptr: from->si_addr);
3468	to->si_addr_lsb = from->si_addr_lsb;
3469	break;
3470	case SIL_FAULT_BNDERR:
3471	to->si_addr = ptr_to_compat(uptr: from->si_addr);
3472	to->si_lower = ptr_to_compat(uptr: from->si_lower);
3473	to->si_upper = ptr_to_compat(uptr: from->si_upper);
3474	break;
3475	case SIL_FAULT_PKUERR:
3476	to->si_addr = ptr_to_compat(uptr: from->si_addr);
3477	to->si_pkey = from->si_pkey;
3478	break;
3479	case SIL_FAULT_PERF_EVENT:
3480	to->si_addr = ptr_to_compat(uptr: from->si_addr);
3481	to->si_perf_data = from->si_perf_data;
3482	to->si_perf_type = from->si_perf_type;
3483	to->si_perf_flags = from->si_perf_flags;
3484	break;
3485	case SIL_CHLD:
3486	to->si_pid = from->si_pid;
3487	to->si_uid = from->si_uid;
3488	to->si_status = from->si_status;
3489	to->si_utime = from->si_utime;
3490	to->si_stime = from->si_stime;
3491	break;
3492	case SIL_RT:
3493	to->si_pid = from->si_pid;
3494	to->si_uid = from->si_uid;
3495	to->si_int = from->si_int;
3496	break;
3497	case SIL_SYS:
3498	to->si_call_addr = ptr_to_compat(uptr: from->si_call_addr);
3499	to->si_syscall = from->si_syscall;
3500	to->si_arch = from->si_arch;
3501	break;
3502	}
3503	}
3504
3505	int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3506	const struct kernel_siginfo *from)
3507	{
3508	struct compat_siginfo new;
3509
3510	copy_siginfo_to_external32(to: &new, from);
3511	if (copy_to_user(to, from: &new, n: sizeof(struct compat_siginfo)))
3512	return -EFAULT;
3513	return 0;
3514	}
3515
3516	static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3517	const struct compat_siginfo *from)
3518	{
3519	clear_siginfo(info: to);
3520	to->si_signo = from->si_signo;
3521	to->si_errno = from->si_errno;
3522	to->si_code = from->si_code;
3523	switch(siginfo_layout(sig: from->si_signo, si_code: from->si_code)) {
3524	case SIL_KILL:
3525	to->si_pid = from->si_pid;
3526	to->si_uid = from->si_uid;
3527	break;
3528	case SIL_TIMER:
3529	to->si_tid = from->si_tid;
3530	to->si_overrun = from->si_overrun;
3531	to->si_int = from->si_int;
3532	break;
3533	case SIL_POLL:
3534	to->si_band = from->si_band;
3535	to->si_fd = from->si_fd;
3536	break;
3537	case SIL_FAULT:
3538	to->si_addr = compat_ptr(uptr: from->si_addr);
3539	break;
3540	case SIL_FAULT_TRAPNO:
3541	to->si_addr = compat_ptr(uptr: from->si_addr);
3542	to->si_trapno = from->si_trapno;
3543	break;
3544	case SIL_FAULT_MCEERR:
3545	to->si_addr = compat_ptr(uptr: from->si_addr);
3546	to->si_addr_lsb = from->si_addr_lsb;
3547	break;
3548	case SIL_FAULT_BNDERR:
3549	to->si_addr = compat_ptr(uptr: from->si_addr);
3550	to->si_lower = compat_ptr(uptr: from->si_lower);
3551	to->si_upper = compat_ptr(uptr: from->si_upper);
3552	break;
3553	case SIL_FAULT_PKUERR:
3554	to->si_addr = compat_ptr(uptr: from->si_addr);
3555	to->si_pkey = from->si_pkey;
3556	break;
3557	case SIL_FAULT_PERF_EVENT:
3558	to->si_addr = compat_ptr(uptr: from->si_addr);
3559	to->si_perf_data = from->si_perf_data;
3560	to->si_perf_type = from->si_perf_type;
3561	to->si_perf_flags = from->si_perf_flags;
3562	break;
3563	case SIL_CHLD:
3564	to->si_pid = from->si_pid;
3565	to->si_uid = from->si_uid;
3566	to->si_status = from->si_status;
3567	#ifdef CONFIG_X86_X32_ABI
3568	if (in_x32_syscall()) {
3569	to->si_utime = from->_sifields._sigchld_x32._utime;
3570	to->si_stime = from->_sifields._sigchld_x32._stime;
3571	} else
3572	#endif
3573	{
3574	to->si_utime = from->si_utime;
3575	to->si_stime = from->si_stime;
3576	}
3577	break;
3578	case SIL_RT:
3579	to->si_pid = from->si_pid;
3580	to->si_uid = from->si_uid;
3581	to->si_int = from->si_int;
3582	break;
3583	case SIL_SYS:
3584	to->si_call_addr = compat_ptr(uptr: from->si_call_addr);
3585	to->si_syscall = from->si_syscall;
3586	to->si_arch = from->si_arch;
3587	break;
3588	}
3589	return 0;
3590	}
3591
3592	static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3593	const struct compat_siginfo __user *ufrom)
3594	{
3595	struct compat_siginfo from;
3596
3597	if (copy_from_user(to: &from, from: ufrom, n: sizeof(struct compat_siginfo)))
3598	return -EFAULT;
3599
3600	from.si_signo = signo;
3601	return post_copy_siginfo_from_user32(to, from: &from);
3602	}
3603
3604	int copy_siginfo_from_user32(struct kernel_siginfo *to,
3605	const struct compat_siginfo __user *ufrom)
3606	{
3607	struct compat_siginfo from;
3608
3609	if (copy_from_user(to: &from, from: ufrom, n: sizeof(struct compat_siginfo)))
3610	return -EFAULT;
3611
3612	return post_copy_siginfo_from_user32(to, from: &from);
3613	}
3614	#endif /* CONFIG_COMPAT */
3615
3616	/**
3617	* do_sigtimedwait - wait for queued signals specified in @which
3618	* @which: queued signals to wait for
3619	* @info: if non-null, the signal's siginfo is returned here
3620	* @ts: upper bound on process time suspension
3621	*/
3622	static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3623	const struct timespec64 *ts)
3624	{
3625	ktime_t *to = NULL, timeout = KTIME_MAX;
3626	struct task_struct *tsk = current;
3627	sigset_t mask = *which;
3628	enum pid_type type;
3629	int sig, ret = 0;
3630
3631	if (ts) {
3632	if (!timespec64_valid(ts))
3633	return -EINVAL;
3634	timeout = timespec64_to_ktime(ts: *ts);
3635	to = &timeout;
3636	}
3637
3638	/*
3639	* Invert the set of allowed signals to get those we want to block.
3640	*/
3641	sigdelsetmask(set: &mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3642	signotset(set: &mask);
3643
3644	spin_lock_irq(lock: &tsk->sighand->siglock);
3645	sig = dequeue_signal(tsk, &mask, info, &type);
3646	if (!sig && timeout) {
3647	/*
3648	* None ready, temporarily unblock those we're interested
3649	* while we are sleeping in so that we'll be awakened when
3650	* they arrive. Unblocking is always fine, we can avoid
3651	* set_current_blocked().
3652	*/
3653	tsk->real_blocked = tsk->blocked;
3654	sigandsets(r: &tsk->blocked, a: &tsk->blocked, b: &mask);
3655	recalc_sigpending();
3656	spin_unlock_irq(lock: &tsk->sighand->siglock);
3657
3658	__set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3659	ret = schedule_hrtimeout_range(expires: to, delta: tsk->timer_slack_ns,
3660	mode: HRTIMER_MODE_REL);
3661	spin_lock_irq(lock: &tsk->sighand->siglock);
3662	__set_task_blocked(tsk, newset: &tsk->real_blocked);
3663	sigemptyset(set: &tsk->real_blocked);
3664	sig = dequeue_signal(tsk, &mask, info, &type);
3665	}
3666	spin_unlock_irq(lock: &tsk->sighand->siglock);
3667
3668	if (sig)
3669	return sig;
3670	return ret ? -EINTR : -EAGAIN;
3671	}
3672
3673	/**
3674	* sys_rt_sigtimedwait - synchronously wait for queued signals specified
3675	* in @uthese
3676	* @uthese: queued signals to wait for
3677	* @uinfo: if non-null, the signal's siginfo is returned here
3678	* @uts: upper bound on process time suspension
3679	* @sigsetsize: size of sigset_t type
3680	*/
3681	SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3682	siginfo_t __user *, uinfo,
3683	const struct __kernel_timespec __user *, uts,
3684	size_t, sigsetsize)
3685	{
3686	sigset_t these;
3687	struct timespec64 ts;
3688	kernel_siginfo_t info;
3689	int ret;
3690
3691	/* XXX: Don't preclude handling different sized sigset_t's. */
3692	if (sigsetsize != sizeof(sigset_t))
3693	return -EINVAL;
3694
3695	if (copy_from_user(to: &these, from: uthese, n: sizeof(these)))
3696	return -EFAULT;
3697
3698	if (uts) {
3699	if (get_timespec64(ts: &ts, uts))
3700	return -EFAULT;
3701	}
3702
3703	ret = do_sigtimedwait(which: &these, info: &info, ts: uts ? &ts : NULL);
3704
3705	if (ret > 0 && uinfo) {
3706	if (copy_siginfo_to_user(to: uinfo, from: &info))
3707	ret = -EFAULT;
3708	}
3709
3710	return ret;
3711	}
3712
3713	#ifdef CONFIG_COMPAT_32BIT_TIME
3714	SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3715	siginfo_t __user *, uinfo,
3716	const struct old_timespec32 __user *, uts,
3717	size_t, sigsetsize)
3718	{
3719	sigset_t these;
3720	struct timespec64 ts;
3721	kernel_siginfo_t info;
3722	int ret;
3723
3724	if (sigsetsize != sizeof(sigset_t))
3725	return -EINVAL;
3726
3727	if (copy_from_user(to: &these, from: uthese, n: sizeof(these)))
3728	return -EFAULT;
3729
3730	if (uts) {
3731	if (get_old_timespec32(&ts, uts))
3732	return -EFAULT;
3733	}
3734
3735	ret = do_sigtimedwait(which: &these, info: &info, ts: uts ? &ts : NULL);
3736
3737	if (ret > 0 && uinfo) {
3738	if (copy_siginfo_to_user(to: uinfo, from: &info))
3739	ret = -EFAULT;
3740	}
3741
3742	return ret;
3743	}
3744	#endif
3745
3746	#ifdef CONFIG_COMPAT
3747	COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3748	struct compat_siginfo __user *, uinfo,
3749	struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3750	{
3751	sigset_t s;
3752	struct timespec64 t;
3753	kernel_siginfo_t info;
3754	long ret;
3755
3756	if (sigsetsize != sizeof(sigset_t))
3757	return -EINVAL;
3758
3759	if (get_compat_sigset(set: &s, compat: uthese))
3760	return -EFAULT;
3761
3762	if (uts) {
3763	if (get_timespec64(ts: &t, uts))
3764	return -EFAULT;
3765	}
3766
3767	ret = do_sigtimedwait(which: &s, info: &info, ts: uts ? &t : NULL);
3768
3769	if (ret > 0 && uinfo) {
3770	if (copy_siginfo_to_user32(to: uinfo, from: &info))
3771	ret = -EFAULT;
3772	}
3773
3774	return ret;
3775	}
3776
3777	#ifdef CONFIG_COMPAT_32BIT_TIME
3778	COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3779	struct compat_siginfo __user *, uinfo,
3780	struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3781	{
3782	sigset_t s;
3783	struct timespec64 t;
3784	kernel_siginfo_t info;
3785	long ret;
3786
3787	if (sigsetsize != sizeof(sigset_t))
3788	return -EINVAL;
3789
3790	if (get_compat_sigset(set: &s, compat: uthese))
3791	return -EFAULT;
3792
3793	if (uts) {
3794	if (get_old_timespec32(&t, uts))
3795	return -EFAULT;
3796	}
3797
3798	ret = do_sigtimedwait(which: &s, info: &info, ts: uts ? &t : NULL);
3799
3800	if (ret > 0 && uinfo) {
3801	if (copy_siginfo_to_user32(to: uinfo, from: &info))
3802	ret = -EFAULT;
3803	}
3804
3805	return ret;
3806	}
3807	#endif
3808	#endif
3809
3810	static void prepare_kill_siginfo(int sig, struct kernel_siginfo *info,
3811	enum pid_type type)
3812	{
3813	clear_siginfo(info);
3814	info->si_signo = sig;
3815	info->si_errno = 0;
3816	info->si_code = (type == PIDTYPE_PID) ? SI_TKILL : SI_USER;
3817	info->si_pid = task_tgid_vnr(current);
3818	info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3819	}
3820
3821	/**
3822	* sys_kill - send a signal to a process
3823	* @pid: the PID of the process
3824	* @sig: signal to be sent
3825	*/
3826	SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3827	{
3828	struct kernel_siginfo info;
3829
3830	prepare_kill_siginfo(sig, info: &info, type: PIDTYPE_TGID);
3831
3832	return kill_something_info(sig, info: &info, pid);
3833	}
3834
3835	/*
3836	* Verify that the signaler and signalee either are in the same pid namespace
3837	* or that the signaler's pid namespace is an ancestor of the signalee's pid
3838	* namespace.
3839	*/
3840	static bool access_pidfd_pidns(struct pid *pid)
3841	{
3842	struct pid_namespace *active = task_active_pid_ns(current);
3843	struct pid_namespace *p = ns_of_pid(pid);
3844
3845	for (;;) {
3846	if (!p)
3847	return false;
3848	if (p == active)
3849	break;
3850	p = p->parent;
3851	}
3852
3853	return true;
3854	}
3855
3856	static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3857	siginfo_t __user *info)
3858	{
3859	#ifdef CONFIG_COMPAT
3860	/*
3861	* Avoid hooking up compat syscalls and instead handle necessary
3862	* conversions here. Note, this is a stop-gap measure and should not be
3863	* considered a generic solution.
3864	*/
3865	if (in_compat_syscall())
3866	return copy_siginfo_from_user32(
3867	to: kinfo, ufrom: (struct compat_siginfo __user *)info);
3868	#endif
3869	return copy_siginfo_from_user(to: kinfo, from: info);
3870	}
3871
3872	static struct pid *pidfd_to_pid(const struct file *file)
3873	{
3874	struct pid *pid;
3875
3876	pid = pidfd_pid(file);
3877	if (!IS_ERR(ptr: pid))
3878	return pid;
3879
3880	return tgid_pidfd_to_pid(file);
3881	}
3882
3883	#define PIDFD_SEND_SIGNAL_FLAGS \
3884	(PIDFD_SIGNAL_THREAD | PIDFD_SIGNAL_THREAD_GROUP | \
3885	PIDFD_SIGNAL_PROCESS_GROUP)
3886
3887	/**
3888	* sys_pidfd_send_signal - Signal a process through a pidfd
3889	* @pidfd: file descriptor of the process
3890	* @sig: signal to send
3891	* @info: signal info
3892	* @flags: future flags
3893	*
3894	* Send the signal to the thread group or to the individual thread depending
3895	* on PIDFD_THREAD.
3896	* In the future extension to @flags may be used to override the default scope
3897	* of @pidfd.
3898	*
3899	* Return: 0 on success, negative errno on failure
3900	*/
3901	SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3902	siginfo_t __user *, info, unsigned int, flags)
3903	{
3904	int ret;
3905	struct fd f;
3906	struct pid *pid;
3907	kernel_siginfo_t kinfo;
3908	enum pid_type type;
3909
3910	/* Enforce flags be set to 0 until we add an extension. */
3911	if (flags & ~PIDFD_SEND_SIGNAL_FLAGS)
3912	return -EINVAL;
3913
3914	/* Ensure that only a single signal scope determining flag is set. */
3915	if (hweight32(flags & PIDFD_SEND_SIGNAL_FLAGS) > 1)
3916	return -EINVAL;
3917
3918	f = fdget(fd: pidfd);
3919	if (!f.file)
3920	return -EBADF;
3921
3922	/* Is this a pidfd? */
3923	pid = pidfd_to_pid(file: f.file);
3924	if (IS_ERR(ptr: pid)) {
3925	ret = PTR_ERR(ptr: pid);
3926	goto err;
3927	}
3928
3929	ret = -EINVAL;
3930	if (!access_pidfd_pidns(pid))
3931	goto err;
3932
3933	switch (flags) {
3934	case 0:
3935	/* Infer scope from the type of pidfd. */
3936	if (f.file->f_flags & PIDFD_THREAD)
3937	type = PIDTYPE_PID;
3938	else
3939	type = PIDTYPE_TGID;
3940	break;
3941	case PIDFD_SIGNAL_THREAD:
3942	type = PIDTYPE_PID;
3943	break;
3944	case PIDFD_SIGNAL_THREAD_GROUP:
3945	type = PIDTYPE_TGID;
3946	break;
3947	case PIDFD_SIGNAL_PROCESS_GROUP:
3948	type = PIDTYPE_PGID;
3949	break;
3950	}
3951
3952	if (info) {
3953	ret = copy_siginfo_from_user_any(kinfo: &kinfo, info);
3954	if (unlikely(ret))
3955	goto err;
3956
3957	ret = -EINVAL;
3958	if (unlikely(sig != kinfo.si_signo))
3959	goto err;
3960
3961	/* Only allow sending arbitrary signals to yourself. */
3962	ret = -EPERM;
3963	if ((task_pid(current) != pid || type > PIDTYPE_TGID) &&
3964	(kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3965	goto err;
3966	} else {
3967	prepare_kill_siginfo(sig, info: &kinfo, type);
3968	}
3969
3970	if (type == PIDTYPE_PGID)
3971	ret = kill_pgrp_info(sig, info: &kinfo, pgrp: pid);
3972	else
3973	ret = kill_pid_info_type(sig, info: &kinfo, pid, type);
3974	err:
3975	fdput(fd: f);
3976	return ret;
3977	}
3978
3979	static int
3980	do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3981	{
3982	struct task_struct *p;
3983	int error = -ESRCH;
3984
3985	rcu_read_lock();
3986	p = find_task_by_vpid(nr: pid);
3987	if (p && (tgid <= 0 || task_tgid_vnr(tsk: p) == tgid)) {
3988	error = check_kill_permission(sig, info, t: p);
3989	/*
3990	* The null signal is a permissions and process existence
3991	* probe. No signal is actually delivered.
3992	*/
3993	if (!error && sig) {
3994	error = do_send_sig_info(sig, info, p, type: PIDTYPE_PID);
3995	/*
3996	* If lock_task_sighand() failed we pretend the task
3997	* dies after receiving the signal. The window is tiny,
3998	* and the signal is private anyway.
3999	*/
4000	if (unlikely(error == -ESRCH))
4001	error = 0;
4002	}
4003	}
4004	rcu_read_unlock();
4005
4006	return error;
4007	}
4008
4009	static int do_tkill(pid_t tgid, pid_t pid, int sig)
4010	{
4011	struct kernel_siginfo info;
4012
4013	prepare_kill_siginfo(sig, info: &info, type: PIDTYPE_PID);
4014
4015	return do_send_specific(tgid, pid, sig, info: &info);
4016	}
4017
4018	/**
4019	* sys_tgkill - send signal to one specific thread
4020	* @tgid: the thread group ID of the thread
4021	* @pid: the PID of the thread
4022	* @sig: signal to be sent
4023	*
4024	* This syscall also checks the @tgid and returns -ESRCH even if the PID
4025	* exists but it's not belonging to the target process anymore. This
4026	* method solves the problem of threads exiting and PIDs getting reused.
4027	*/
4028	SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
4029	{
4030	/* This is only valid for single tasks */
4031	if (pid <= 0 || tgid <= 0)
4032	return -EINVAL;
4033
4034	return do_tkill(tgid, pid, sig);
4035	}
4036
4037	/**
4038	* sys_tkill - send signal to one specific task
4039	* @pid: the PID of the task
4040	* @sig: signal to be sent
4041	*
4042	* Send a signal to only one task, even if it's a CLONE_THREAD task.
4043	*/
4044	SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4045	{
4046	/* This is only valid for single tasks */
4047	if (pid <= 0)
4048	return -EINVAL;
4049
4050	return do_tkill(tgid: 0, pid, sig);
4051	}
4052
4053	static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4054	{
4055	/* Not even root can pretend to send signals from the kernel.
4056	* Nor can they impersonate a kill()/tgkill(), which adds source info.
4057	*/
4058	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4059	(task_pid_vnr(current) != pid))
4060	return -EPERM;
4061
4062	/* POSIX.1b doesn't mention process groups. */
4063	return kill_proc_info(sig, info, pid);
4064	}
4065
4066	/**
4067	* sys_rt_sigqueueinfo - send signal information to a signal
4068	* @pid: the PID of the thread
4069	* @sig: signal to be sent
4070	* @uinfo: signal info to be sent
4071	*/
4072	SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4073	siginfo_t __user *, uinfo)
4074	{
4075	kernel_siginfo_t info;
4076	int ret = __copy_siginfo_from_user(signo: sig, to: &info, from: uinfo);
4077	if (unlikely(ret))
4078	return ret;
4079	return do_rt_sigqueueinfo(pid, sig, info: &info);
4080	}
4081
4082	#ifdef CONFIG_COMPAT
4083	COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4084	compat_pid_t, pid,
4085	int, sig,
4086	struct compat_siginfo __user *, uinfo)
4087	{
4088	kernel_siginfo_t info;
4089	int ret = __copy_siginfo_from_user32(signo: sig, to: &info, ufrom: uinfo);
4090	if (unlikely(ret))
4091	return ret;
4092	return do_rt_sigqueueinfo(pid, sig, info: &info);
4093	}
4094	#endif
4095
4096	static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4097	{
4098	/* This is only valid for single tasks */
4099	if (pid <= 0 || tgid <= 0)
4100	return -EINVAL;
4101
4102	/* Not even root can pretend to send signals from the kernel.
4103	* Nor can they impersonate a kill()/tgkill(), which adds source info.
4104	*/
4105	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4106	(task_pid_vnr(current) != pid))
4107	return -EPERM;
4108
4109	return do_send_specific(tgid, pid, sig, info);
4110	}
4111
4112	SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4113	siginfo_t __user *, uinfo)
4114	{
4115	kernel_siginfo_t info;
4116	int ret = __copy_siginfo_from_user(signo: sig, to: &info, from: uinfo);
4117	if (unlikely(ret))
4118	return ret;
4119	return do_rt_tgsigqueueinfo(tgid, pid, sig, info: &info);
4120	}
4121
4122	#ifdef CONFIG_COMPAT
4123	COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4124	compat_pid_t, tgid,
4125	compat_pid_t, pid,
4126	int, sig,
4127	struct compat_siginfo __user *, uinfo)
4128	{
4129	kernel_siginfo_t info;
4130	int ret = __copy_siginfo_from_user32(signo: sig, to: &info, ufrom: uinfo);
4131	if (unlikely(ret))
4132	return ret;
4133	return do_rt_tgsigqueueinfo(tgid, pid, sig, info: &info);
4134	}
4135	#endif
4136
4137	/*
4138	* For kthreads only, must not be used if cloned with CLONE_SIGHAND
4139	*/
4140	void kernel_sigaction(int sig, __sighandler_t action)
4141	{
4142	spin_lock_irq(lock: &current->sighand->siglock);
4143	current->sighand->action[sig - 1].sa.sa_handler = action;
4144	if (action == SIG_IGN) {
4145	sigset_t mask;
4146
4147	sigemptyset(set: &mask);
4148	sigaddset(set: &mask, sig: sig);
4149
4150	flush_sigqueue_mask(mask: &mask, s: &current->signal->shared_pending);
4151	flush_sigqueue_mask(mask: &mask, s: &current->pending);
4152	recalc_sigpending();
4153	}
4154	spin_unlock_irq(lock: &current->sighand->siglock);
4155	}
4156	EXPORT_SYMBOL(kernel_sigaction);
4157
4158	void __weak sigaction_compat_abi(struct k_sigaction *act,
4159	struct k_sigaction *oact)
4160	{
4161	}
4162
4163	int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4164	{
4165	struct task_struct *p = current, *t;
4166	struct k_sigaction *k;
4167	sigset_t mask;
4168
4169	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4170	return -EINVAL;
4171
4172	k = &p->sighand->action[sig-1];
4173
4174	spin_lock_irq(lock: &p->sighand->siglock);
4175	if (k->sa.sa_flags & SA_IMMUTABLE) {
4176	spin_unlock_irq(lock: &p->sighand->siglock);
4177	return -EINVAL;
4178	}
4179	if (oact)
4180	*oact = *k;
4181
4182	/*
4183	* Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4184	* e.g. by having an architecture use the bit in their uapi.
4185	*/
4186	BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4187
4188	/*
4189	* Clear unknown flag bits in order to allow userspace to detect missing
4190	* support for flag bits and to allow the kernel to use non-uapi bits
4191	* internally.
4192	*/
4193	if (act)
4194	act->sa.sa_flags &= UAPI_SA_FLAGS;
4195	if (oact)
4196	oact->sa.sa_flags &= UAPI_SA_FLAGS;
4197
4198	sigaction_compat_abi(act, oact);
4199
4200	if (act) {
4201	sigdelsetmask(set: &act->sa.sa_mask,
4202	sigmask(SIGKILL) | sigmask(SIGSTOP));
4203	*k = *act;
4204	/*
4205	* POSIX 3.3.1.3:
4206	* "Setting a signal action to SIG_IGN for a signal that is
4207	* pending shall cause the pending signal to be discarded,
4208	* whether or not it is blocked."
4209	*
4210	* "Setting a signal action to SIG_DFL for a signal that is
4211	* pending and whose default action is to ignore the signal
4212	* (for example, SIGCHLD), shall cause the pending signal to
4213	* be discarded, whether or not it is blocked"
4214	*/
4215	if (sig_handler_ignored(handler: sig_handler(t: p, sig), sig)) {
4216	sigemptyset(set: &mask);
4217	sigaddset(set: &mask, sig: sig);
4218	flush_sigqueue_mask(mask: &mask, s: &p->signal->shared_pending);
4219	for_each_thread(p, t)
4220	flush_sigqueue_mask(mask: &mask, s: &t->pending);
4221	}
4222	}
4223
4224	spin_unlock_irq(lock: &p->sighand->siglock);
4225	return 0;
4226	}
4227
4228	#ifdef CONFIG_DYNAMIC_SIGFRAME
4229	static inline void sigaltstack_lock(void)
4230	__acquires(&current->sighand->siglock)
4231	{
4232	spin_lock_irq(lock: &current->sighand->siglock);
4233	}
4234
4235	static inline void sigaltstack_unlock(void)
4236	__releases(&current->sighand->siglock)
4237	{
4238	spin_unlock_irq(lock: &current->sighand->siglock);
4239	}
4240	#else
4241	static inline void sigaltstack_lock(void) { }
4242	static inline void sigaltstack_unlock(void) { }
4243	#endif
4244
4245	static int
4246	do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4247	size_t min_ss_size)
4248	{
4249	struct task_struct *t = current;
4250	int ret = 0;
4251
4252	if (oss) {
4253	memset(oss, 0, sizeof(stack_t));
4254	oss->ss_sp = (void __user *) t->sas_ss_sp;
4255	oss->ss_size = t->sas_ss_size;
4256	oss->ss_flags = sas_ss_flags(sp) |
4257	(current->sas_ss_flags & SS_FLAG_BITS);
4258	}
4259
4260	if (ss) {
4261	void __user *ss_sp = ss->ss_sp;
4262	size_t ss_size = ss->ss_size;
4263	unsigned ss_flags = ss->ss_flags;
4264	int ss_mode;
4265
4266	if (unlikely(on_sig_stack(sp)))
4267	return -EPERM;
4268
4269	ss_mode = ss_flags & ~SS_FLAG_BITS;
4270	if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4271	ss_mode != 0))
4272	return -EINVAL;
4273
4274	/*
4275	* Return before taking any locks if no actual
4276	* sigaltstack changes were requested.
4277	*/
4278	if (t->sas_ss_sp == (unsigned long)ss_sp &&
4279	t->sas_ss_size == ss_size &&
4280	t->sas_ss_flags == ss_flags)
4281	return 0;
4282
4283	sigaltstack_lock();
4284	if (ss_mode == SS_DISABLE) {
4285	ss_size = 0;
4286	ss_sp = NULL;
4287	} else {
4288	if (unlikely(ss_size < min_ss_size))
4289	ret = -ENOMEM;
4290	if (!sigaltstack_size_valid(ss_size))
4291	ret = -ENOMEM;
4292	}
4293	if (!ret) {
4294	t->sas_ss_sp = (unsigned long) ss_sp;
4295	t->sas_ss_size = ss_size;
4296	t->sas_ss_flags = ss_flags;
4297	}
4298	sigaltstack_unlock();
4299	}
4300	return ret;
4301	}
4302
4303	SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4304	{
4305	stack_t new, old;
4306	int err;
4307	if (uss && copy_from_user(to: &new, from: uss, n: sizeof(stack_t)))
4308	return -EFAULT;
4309	err = do_sigaltstack(ss: uss ? &new : NULL, oss: uoss ? &old : NULL,
4310	current_user_stack_pointer(),
4311	MINSIGSTKSZ);
4312	if (!err && uoss && copy_to_user(to: uoss, from: &old, n: sizeof(stack_t)))
4313	err = -EFAULT;
4314	return err;
4315	}
4316
4317	int restore_altstack(const stack_t __user *uss)
4318	{
4319	stack_t new;
4320	if (copy_from_user(to: &new, from: uss, n: sizeof(stack_t)))
4321	return -EFAULT;
4322	(void)do_sigaltstack(ss: &new, NULL, current_user_stack_pointer(),
4323	MINSIGSTKSZ);
4324	/* squash all but EFAULT for now */
4325	return 0;
4326	}
4327
4328	int __save_altstack(stack_t __user *uss, unsigned long sp)
4329	{
4330	struct task_struct *t = current;
4331	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4332	__put_user(t->sas_ss_flags, &uss->ss_flags) |
4333	__put_user(t->sas_ss_size, &uss->ss_size);
4334	return err;
4335	}
4336
4337	#ifdef CONFIG_COMPAT
4338	static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4339	compat_stack_t __user *uoss_ptr)
4340	{
4341	stack_t uss, uoss;
4342	int ret;
4343
4344	if (uss_ptr) {
4345	compat_stack_t uss32;
4346	if (copy_from_user(to: &uss32, from: uss_ptr, n: sizeof(compat_stack_t)))
4347	return -EFAULT;
4348	uss.ss_sp = compat_ptr(uptr: uss32.ss_sp);
4349	uss.ss_flags = uss32.ss_flags;
4350	uss.ss_size = uss32.ss_size;
4351	}
4352	ret = do_sigaltstack(ss: uss_ptr ? &uss : NULL, oss: &uoss,
4353	compat_user_stack_pointer(),
4354	COMPAT_MINSIGSTKSZ);
4355	if (ret >= 0 && uoss_ptr) {
4356	compat_stack_t old;
4357	memset(&old, 0, sizeof(old));
4358	old.ss_sp = ptr_to_compat(uptr: uoss.ss_sp);
4359	old.ss_flags = uoss.ss_flags;
4360	old.ss_size = uoss.ss_size;
4361	if (copy_to_user(to: uoss_ptr, from: &old, n: sizeof(compat_stack_t)))
4362	ret = -EFAULT;
4363	}
4364	return ret;
4365	}
4366
4367	COMPAT_SYSCALL_DEFINE2(sigaltstack,
4368	const compat_stack_t __user *, uss_ptr,
4369	compat_stack_t __user *, uoss_ptr)
4370	{
4371	return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4372	}
4373
4374	int compat_restore_altstack(const compat_stack_t __user *uss)
4375	{
4376	int err = do_compat_sigaltstack(uss_ptr: uss, NULL);
4377	/* squash all but -EFAULT for now */
4378	return err == -EFAULT ? err : 0;
4379	}
4380
4381	int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4382	{
4383	int err;
4384	struct task_struct *t = current;
4385	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4386	&uss->ss_sp) |
4387	__put_user(t->sas_ss_flags, &uss->ss_flags) |
4388	__put_user(t->sas_ss_size, &uss->ss_size);
4389	return err;
4390	}
4391	#endif
4392
4393	#ifdef __ARCH_WANT_SYS_SIGPENDING
4394
4395	/**
4396	* sys_sigpending - examine pending signals
4397	* @uset: where mask of pending signal is returned
4398	*/
4399	SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4400	{
4401	sigset_t set;
4402
4403	if (sizeof(old_sigset_t) > sizeof(*uset))
4404	return -EINVAL;
4405
4406	do_sigpending(set: &set);
4407
4408	if (copy_to_user(to: uset, from: &set, n: sizeof(old_sigset_t)))
4409	return -EFAULT;
4410
4411	return 0;
4412	}
4413
4414	#ifdef CONFIG_COMPAT
4415	COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4416	{
4417	sigset_t set;
4418
4419	do_sigpending(set: &set);
4420
4421	return put_user(set.sig[0], set32);
4422	}
4423	#endif
4424
4425	#endif
4426
4427	#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4428	/**
4429	* sys_sigprocmask - examine and change blocked signals
4430	* @how: whether to add, remove, or set signals
4431	* @nset: signals to add or remove (if non-null)
4432	* @oset: previous value of signal mask if non-null
4433	*
4434	* Some platforms have their own version with special arguments;
4435	* others support only sys_rt_sigprocmask.
4436	*/
4437
4438	SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4439	old_sigset_t __user *, oset)
4440	{
4441	old_sigset_t old_set, new_set;
4442	sigset_t new_blocked;
4443
4444	old_set = current->blocked.sig[0];
4445
4446	if (nset) {
4447	if (copy_from_user(to: &new_set, from: nset, n: sizeof(*nset)))
4448	return -EFAULT;
4449
4450	new_blocked = current->blocked;
4451
4452	switch (how) {
4453	case SIG_BLOCK:
4454	sigaddsetmask(set: &new_blocked, mask: new_set);
4455	break;
4456	case SIG_UNBLOCK:
4457	sigdelsetmask(set: &new_blocked, mask: new_set);
4458	break;
4459	case SIG_SETMASK:
4460	new_blocked.sig[0] = new_set;
4461	break;
4462	default:
4463	return -EINVAL;
4464	}
4465
4466	set_current_blocked(&new_blocked);
4467	}
4468
4469	if (oset) {
4470	if (copy_to_user(to: oset, from: &old_set, n: sizeof(*oset)))
4471	return -EFAULT;
4472	}
4473
4474	return 0;
4475	}
4476	#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4477
4478	#ifndef CONFIG_ODD_RT_SIGACTION
4479	/**
4480	* sys_rt_sigaction - alter an action taken by a process
4481	* @sig: signal to be sent
4482	* @act: new sigaction
4483	* @oact: used to save the previous sigaction
4484	* @sigsetsize: size of sigset_t type
4485	*/
4486	SYSCALL_DEFINE4(rt_sigaction, int, sig,
4487	const struct sigaction __user *, act,
4488	struct sigaction __user *, oact,
4489	size_t, sigsetsize)
4490	{
4491	struct k_sigaction new_sa, old_sa;
4492	int ret;
4493
4494	/* XXX: Don't preclude handling different sized sigset_t's. */
4495	if (sigsetsize != sizeof(sigset_t))
4496	return -EINVAL;
4497
4498	if (act && copy_from_user(to: &new_sa.sa, from: act, n: sizeof(new_sa.sa)))
4499	return -EFAULT;
4500
4501	ret = do_sigaction(sig, act: act ? &new_sa : NULL, oact: oact ? &old_sa : NULL);
4502	if (ret)
4503	return ret;
4504
4505	if (oact && copy_to_user(to: oact, from: &old_sa.sa, n: sizeof(old_sa.sa)))
4506	return -EFAULT;
4507
4508	return 0;
4509	}
4510	#ifdef CONFIG_COMPAT
4511	COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4512	const struct compat_sigaction __user *, act,
4513	struct compat_sigaction __user *, oact,
4514	compat_size_t, sigsetsize)
4515	{
4516	struct k_sigaction new_ka, old_ka;
4517	#ifdef __ARCH_HAS_SA_RESTORER
4518	compat_uptr_t restorer;
4519	#endif
4520	int ret;
4521
4522	/* XXX: Don't preclude handling different sized sigset_t's. */
4523	if (sigsetsize != sizeof(compat_sigset_t))
4524	return -EINVAL;
4525
4526	if (act) {
4527	compat_uptr_t handler;
4528	ret = get_user(handler, &act->sa_handler);
4529	new_ka.sa.sa_handler = compat_ptr(uptr: handler);
4530	#ifdef __ARCH_HAS_SA_RESTORER
4531	ret |= get_user(restorer, &act->sa_restorer);
4532	new_ka.sa.sa_restorer = compat_ptr(uptr: restorer);
4533	#endif
4534	ret |= get_compat_sigset(set: &new_ka.sa.sa_mask, compat: &act->sa_mask);
4535	ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4536	if (ret)
4537	return -EFAULT;
4538	}
4539
4540	ret = do_sigaction(sig, act: act ? &new_ka : NULL, oact: oact ? &old_ka : NULL);
4541	if (!ret && oact) {
4542	ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4543	&oact->sa_handler);
4544	ret |= put_compat_sigset(compat: &oact->sa_mask, set: &old_ka.sa.sa_mask,
4545	size: sizeof(oact->sa_mask));
4546	ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4547	#ifdef __ARCH_HAS_SA_RESTORER
4548	ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4549	&oact->sa_restorer);
4550	#endif
4551	}
4552	return ret;
4553	}
4554	#endif
4555	#endif /* !CONFIG_ODD_RT_SIGACTION */
4556
4557	#ifdef CONFIG_OLD_SIGACTION
4558	SYSCALL_DEFINE3(sigaction, int, sig,
4559	const struct old_sigaction __user *, act,
4560	struct old_sigaction __user *, oact)
4561	{
4562	struct k_sigaction new_ka, old_ka;
4563	int ret;
4564
4565	if (act) {
4566	old_sigset_t mask;
4567	if (!access_ok(act, sizeof(*act)) ||
4568	__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4569	__get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4570	__get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4571	__get_user(mask, &act->sa_mask))
4572	return -EFAULT;
4573	#ifdef __ARCH_HAS_KA_RESTORER
4574	new_ka.ka_restorer = NULL;
4575	#endif
4576	siginitset(&new_ka.sa.sa_mask, mask);
4577	}
4578
4579	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4580
4581	if (!ret && oact) {
4582	if (!access_ok(oact, sizeof(*oact)) ||
4583	__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4584	__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4585	__put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4586	__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4587	return -EFAULT;
4588	}
4589
4590	return ret;
4591	}
4592	#endif
4593	#ifdef CONFIG_COMPAT_OLD_SIGACTION
4594	COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4595	const struct compat_old_sigaction __user *, act,
4596	struct compat_old_sigaction __user *, oact)
4597	{
4598	struct k_sigaction new_ka, old_ka;
4599	int ret;
4600	compat_old_sigset_t mask;
4601	compat_uptr_t handler, restorer;
4602
4603	if (act) {
4604	if (!access_ok(act, sizeof(*act)) ||
4605	__get_user(handler, &act->sa_handler) ||
4606	__get_user(restorer, &act->sa_restorer) ||
4607	__get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4608	__get_user(mask, &act->sa_mask))
4609	return -EFAULT;
4610
4611	#ifdef __ARCH_HAS_KA_RESTORER
4612	new_ka.ka_restorer = NULL;
4613	#endif
4614	new_ka.sa.sa_handler = compat_ptr(uptr: handler);
4615	new_ka.sa.sa_restorer = compat_ptr(uptr: restorer);
4616	siginitset(set: &new_ka.sa.sa_mask, mask);
4617	}
4618
4619	ret = do_sigaction(sig, act: act ? &new_ka : NULL, oact: oact ? &old_ka : NULL);
4620
4621	if (!ret && oact) {
4622	if (!access_ok(oact, sizeof(*oact)) ||
4623	__put_user(ptr_to_compat(old_ka.sa.sa_handler),
4624	&oact->sa_handler) ||
4625	__put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4626	&oact->sa_restorer) ||
4627	__put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4628	__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4629	return -EFAULT;
4630	}
4631	return ret;
4632	}
4633	#endif
4634
4635	#ifdef CONFIG_SGETMASK_SYSCALL
4636
4637	/*
4638	* For backwards compatibility. Functionality superseded by sigprocmask.
4639	*/
4640	SYSCALL_DEFINE0(sgetmask)
4641	{
4642	/* SMP safe */
4643	return current->blocked.sig[0];
4644	}
4645
4646	SYSCALL_DEFINE1(ssetmask, int, newmask)
4647	{
4648	int old = current->blocked.sig[0];
4649	sigset_t newset;
4650
4651	siginitset(set: &newset, mask: newmask);
4652	set_current_blocked(&newset);
4653
4654	return old;
4655	}
4656	#endif /* CONFIG_SGETMASK_SYSCALL */
4657
4658	#ifdef __ARCH_WANT_SYS_SIGNAL
4659	/*
4660	* For backwards compatibility. Functionality superseded by sigaction.
4661	*/
4662	SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4663	{
4664	struct k_sigaction new_sa, old_sa;
4665	int ret;
4666
4667	new_sa.sa.sa_handler = handler;
4668	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4669	sigemptyset(set: &new_sa.sa.sa_mask);
4670
4671	ret = do_sigaction(sig, act: &new_sa, oact: &old_sa);
4672
4673	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4674	}
4675	#endif /* __ARCH_WANT_SYS_SIGNAL */
4676
4677	#ifdef __ARCH_WANT_SYS_PAUSE
4678
4679	SYSCALL_DEFINE0(pause)
4680	{
4681	while (!signal_pending(current)) {
4682	__set_current_state(TASK_INTERRUPTIBLE);
4683	schedule();
4684	}
4685	return -ERESTARTNOHAND;
4686	}
4687
4688	#endif
4689
4690	static int sigsuspend(sigset_t *set)
4691	{
4692	current->saved_sigmask = current->blocked;
4693	set_current_blocked(set);
4694
4695	while (!signal_pending(current)) {
4696	__set_current_state(TASK_INTERRUPTIBLE);
4697	schedule();
4698	}
4699	set_restore_sigmask();
4700	return -ERESTARTNOHAND;
4701	}
4702
4703	/**
4704	* sys_rt_sigsuspend - replace the signal mask for a value with the
4705	* @unewset value until a signal is received
4706	* @unewset: new signal mask value
4707	* @sigsetsize: size of sigset_t type
4708	*/
4709	SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4710	{
4711	sigset_t newset;
4712
4713	/* XXX: Don't preclude handling different sized sigset_t's. */
4714	if (sigsetsize != sizeof(sigset_t))
4715	return -EINVAL;
4716
4717	if (copy_from_user(to: &newset, from: unewset, n: sizeof(newset)))
4718	return -EFAULT;
4719	return sigsuspend(set: &newset);
4720	}
4721
4722	#ifdef CONFIG_COMPAT
4723	COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4724	{
4725	sigset_t newset;
4726
4727	/* XXX: Don't preclude handling different sized sigset_t's. */
4728	if (sigsetsize != sizeof(sigset_t))
4729	return -EINVAL;
4730
4731	if (get_compat_sigset(set: &newset, compat: unewset))
4732	return -EFAULT;
4733	return sigsuspend(set: &newset);
4734	}
4735	#endif
4736
4737	#ifdef CONFIG_OLD_SIGSUSPEND
4738	SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4739	{
4740	sigset_t blocked;
4741	siginitset(&blocked, mask);
4742	return sigsuspend(&blocked);
4743	}
4744	#endif
4745	#ifdef CONFIG_OLD_SIGSUSPEND3
4746	SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4747	{
4748	sigset_t blocked;
4749	siginitset(set: &blocked, mask);
4750	return sigsuspend(set: &blocked);
4751	}
4752	#endif
4753
4754	__weak const char *arch_vma_name(struct vm_area_struct *vma)
4755	{
4756	return NULL;
4757	}
4758
4759	static inline void siginfo_buildtime_checks(void)
4760	{
4761	BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4762
4763	/* Verify the offsets in the two siginfos match */
4764	#define CHECK_OFFSET(field) \
4765	BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4766
4767	/* kill */
4768	CHECK_OFFSET(si_pid);
4769	CHECK_OFFSET(si_uid);
4770
4771	/* timer */
4772	CHECK_OFFSET(si_tid);
4773	CHECK_OFFSET(si_overrun);
4774	CHECK_OFFSET(si_value);
4775
4776	/* rt */
4777	CHECK_OFFSET(si_pid);
4778	CHECK_OFFSET(si_uid);
4779	CHECK_OFFSET(si_value);
4780
4781	/* sigchld */
4782	CHECK_OFFSET(si_pid);
4783	CHECK_OFFSET(si_uid);
4784	CHECK_OFFSET(si_status);
4785	CHECK_OFFSET(si_utime);
4786	CHECK_OFFSET(si_stime);
4787
4788	/* sigfault */
4789	CHECK_OFFSET(si_addr);
4790	CHECK_OFFSET(si_trapno);
4791	CHECK_OFFSET(si_addr_lsb);
4792	CHECK_OFFSET(si_lower);
4793	CHECK_OFFSET(si_upper);
4794	CHECK_OFFSET(si_pkey);
4795	CHECK_OFFSET(si_perf_data);
4796	CHECK_OFFSET(si_perf_type);
4797	CHECK_OFFSET(si_perf_flags);
4798
4799	/* sigpoll */
4800	CHECK_OFFSET(si_band);
4801	CHECK_OFFSET(si_fd);
4802
4803	/* sigsys */
4804	CHECK_OFFSET(si_call_addr);
4805	CHECK_OFFSET(si_syscall);
4806	CHECK_OFFSET(si_arch);
4807	#undef CHECK_OFFSET
4808
4809	/* usb asyncio */
4810	BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4811	offsetof(struct siginfo, si_addr));
4812	if (sizeof(int) == sizeof(void __user *)) {
4813	BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4814	sizeof(void __user *));
4815	} else {
4816	BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4817	sizeof_field(struct siginfo, si_uid)) !=
4818	sizeof(void __user *));
4819	BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4820	offsetof(struct siginfo, si_uid));
4821	}
4822	#ifdef CONFIG_COMPAT
4823	BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4824	offsetof(struct compat_siginfo, si_addr));
4825	BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4826	sizeof(compat_uptr_t));
4827	BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4828	sizeof_field(struct siginfo, si_pid));
4829	#endif
4830	}
4831
4832	#if defined(CONFIG_SYSCTL)
4833	static struct ctl_table signal_debug_table[] = {
4834	#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4835	{
4836	.procname = "exception-trace",
4837	.data = &show_unhandled_signals,
4838	.maxlen = sizeof(int),
4839	.mode = 0644,
4840	.proc_handler = proc_dointvec
4841	},
4842	#endif
4843	{ }
4844	};
4845
4846	static int __init init_signal_sysctls(void)
4847	{
4848	register_sysctl_init("debug", signal_debug_table);
4849	return 0;
4850	}
4851	early_initcall(init_signal_sysctls);
4852	#endif /* CONFIG_SYSCTL */
4853
4854	void __init signals_init(void)
4855	{
4856	siginfo_buildtime_checks();
4857
4858	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4859	}
4860
4861	#ifdef CONFIG_KGDB_KDB
4862	#include <linux/kdb.h>
4863	/*
4864	* kdb_send_sig - Allows kdb to send signals without exposing
4865	* signal internals. This function checks if the required locks are
4866	* available before calling the main signal code, to avoid kdb
4867	* deadlocks.
4868	*/
4869	void kdb_send_sig(struct task_struct *t, int sig)
4870	{
4871	static struct task_struct *kdb_prev_t;
4872	int new_t, ret;
4873	if (!spin_trylock(lock: &t->sighand->siglock)) {
4874	kdb_printf("Can't do kill command now.\n"
4875	"The sigmask lock is held somewhere else in "
4876	"kernel, try again later\n");
4877	return;
4878	}
4879	new_t = kdb_prev_t != t;
4880	kdb_prev_t = t;
4881	if (!task_is_running(t) && new_t) {
4882	spin_unlock(lock: &t->sighand->siglock);
4883	kdb_printf("Process is not RUNNING, sending a signal from "
4884	"kdb risks deadlock\n"
4885	"on the run queue locks. "
4886	"The signal has _not_ been sent.\n"
4887	"Reissue the kill command if you want to risk "
4888	"the deadlock.\n");
4889	return;
4890	}
4891	ret = send_signal_locked(sig, SEND_SIG_PRIV, t, type: PIDTYPE_PID);
4892	spin_unlock(lock: &t->sighand->siglock);
4893	if (ret)
4894	kdb_printf("Fail to deliver Signal %d to process %d.\n",
4895	sig, t->pid);
4896	else
4897	kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4898	}
4899	#endif /* CONFIG_KGDB_KDB */
4900