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 
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/signal.h>
53 
54 #include <asm/param.h>
55 #include <linux/uaccess.h>
56 #include <asm/unistd.h>
57 #include <asm/siginfo.h>
58 #include <asm/cacheflush.h>
59 #include <asm/syscall.h>	/* for syscall_get_* */
60 
61 /*
62  * SLAB caches for signal bits.
63  */
64 
65 static struct kmem_cache *sigqueue_cachep;
66 
67 int print_fatal_signals __read_mostly;
68 
sig_handler(struct task_struct * t,int sig)69 static void __user *sig_handler(struct task_struct *t, int sig)
70 {
71 	return t->sighand->action[sig - 1].sa.sa_handler;
72 }
73 
sig_handler_ignored(void __user * handler,int sig)74 static inline bool sig_handler_ignored(void __user *handler, int sig)
75 {
76 	/* Is it explicitly or implicitly ignored? */
77 	return handler == SIG_IGN ||
78 	       (handler == SIG_DFL && sig_kernel_ignore(sig));
79 }
80 
sig_task_ignored(struct task_struct * t,int sig,bool force)81 static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
82 {
83 	void __user *handler;
84 
85 	handler = sig_handler(t, sig);
86 
87 	/* SIGKILL and SIGSTOP may not be sent to the global init */
88 	if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
89 		return true;
90 
91 	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
92 	    handler == SIG_DFL && !(force && sig_kernel_only(sig)))
93 		return true;
94 
95 	/* Only allow kernel generated signals to this kthread */
96 	if (unlikely((t->flags & PF_KTHREAD) &&
97 		     (handler == SIG_KTHREAD_KERNEL) && !force))
98 		return true;
99 
100 	return sig_handler_ignored(handler, sig);
101 }
102 
sig_ignored(struct task_struct * t,int sig,bool force)103 static bool sig_ignored(struct task_struct *t, int sig, bool force)
104 {
105 	/*
106 	 * Blocked signals are never ignored, since the
107 	 * signal handler may change by the time it is
108 	 * unblocked.
109 	 */
110 	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
111 		return false;
112 
113 	/*
114 	 * Tracers may want to know about even ignored signal unless it
115 	 * is SIGKILL which can't be reported anyway but can be ignored
116 	 * by SIGNAL_UNKILLABLE task.
117 	 */
118 	if (t->ptrace && sig != SIGKILL)
119 		return false;
120 
121 	return sig_task_ignored(t, sig, force);
122 }
123 
124 /*
125  * Re-calculate pending state from the set of locally pending
126  * signals, globally pending signals, and blocked signals.
127  */
has_pending_signals(sigset_t * signal,sigset_t * blocked)128 static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
129 {
130 	unsigned long ready;
131 	long i;
132 
133 	switch (_NSIG_WORDS) {
134 	default:
135 		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
136 			ready |= signal->sig[i] &~ blocked->sig[i];
137 		break;
138 
139 	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
140 		ready |= signal->sig[2] &~ blocked->sig[2];
141 		ready |= signal->sig[1] &~ blocked->sig[1];
142 		ready |= signal->sig[0] &~ blocked->sig[0];
143 		break;
144 
145 	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
146 		ready |= signal->sig[0] &~ blocked->sig[0];
147 		break;
148 
149 	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
150 	}
151 	return ready !=	0;
152 }
153 
154 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
155 
recalc_sigpending_tsk(struct task_struct * t)156 static bool recalc_sigpending_tsk(struct task_struct *t)
157 {
158 	if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
159 	    PENDING(&t->pending, &t->blocked) ||
160 	    PENDING(&t->signal->shared_pending, &t->blocked) ||
161 	    cgroup_task_frozen(t)) {
162 		set_tsk_thread_flag(t, TIF_SIGPENDING);
163 		return true;
164 	}
165 
166 	/*
167 	 * We must never clear the flag in another thread, or in current
168 	 * when it's possible the current syscall is returning -ERESTART*.
169 	 * So we don't clear it here, and only callers who know they should do.
170 	 */
171 	return false;
172 }
173 
174 /*
175  * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
176  * This is superfluous when called on current, the wakeup is a harmless no-op.
177  */
recalc_sigpending_and_wake(struct task_struct * t)178 void recalc_sigpending_and_wake(struct task_struct *t)
179 {
180 	if (recalc_sigpending_tsk(t))
181 		signal_wake_up(t, 0);
182 }
183 
recalc_sigpending(void)184 void recalc_sigpending(void)
185 {
186 	if (!recalc_sigpending_tsk(current) && !freezing(current))
187 		clear_thread_flag(TIF_SIGPENDING);
188 
189 }
190 EXPORT_SYMBOL(recalc_sigpending);
191 
calculate_sigpending(void)192 void calculate_sigpending(void)
193 {
194 	/* Have any signals or users of TIF_SIGPENDING been delayed
195 	 * until after fork?
196 	 */
197 	spin_lock_irq(&current->sighand->siglock);
198 	set_tsk_thread_flag(current, TIF_SIGPENDING);
199 	recalc_sigpending();
200 	spin_unlock_irq(&current->sighand->siglock);
201 }
202 
203 /* Given the mask, find the first available signal that should be serviced. */
204 
205 #define SYNCHRONOUS_MASK \
206 	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
207 	 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
208 
next_signal(struct sigpending * pending,sigset_t * mask)209 int next_signal(struct sigpending *pending, sigset_t *mask)
210 {
211 	unsigned long i, *s, *m, x;
212 	int sig = 0;
213 
214 	s = pending->signal.sig;
215 	m = mask->sig;
216 
217 	/*
218 	 * Handle the first word specially: it contains the
219 	 * synchronous signals that need to be dequeued first.
220 	 */
221 	x = *s &~ *m;
222 	if (x) {
223 		if (x & SYNCHRONOUS_MASK)
224 			x &= SYNCHRONOUS_MASK;
225 		sig = ffz(~x) + 1;
226 		return sig;
227 	}
228 
229 	switch (_NSIG_WORDS) {
230 	default:
231 		for (i = 1; i < _NSIG_WORDS; ++i) {
232 			x = *++s &~ *++m;
233 			if (!x)
234 				continue;
235 			sig = ffz(~x) + i*_NSIG_BPW + 1;
236 			break;
237 		}
238 		break;
239 
240 	case 2:
241 		x = s[1] &~ m[1];
242 		if (!x)
243 			break;
244 		sig = ffz(~x) + _NSIG_BPW + 1;
245 		break;
246 
247 	case 1:
248 		/* Nothing to do */
249 		break;
250 	}
251 
252 	return sig;
253 }
254 
print_dropped_signal(int sig)255 static inline void print_dropped_signal(int sig)
256 {
257 	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
258 
259 	if (!print_fatal_signals)
260 		return;
261 
262 	if (!__ratelimit(&ratelimit_state))
263 		return;
264 
265 	pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
266 				current->comm, current->pid, sig);
267 }
268 
269 /**
270  * task_set_jobctl_pending - set jobctl pending bits
271  * @task: target task
272  * @mask: pending bits to set
273  *
274  * Clear @mask from @task->jobctl.  @mask must be subset of
275  * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
276  * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
277  * cleared.  If @task is already being killed or exiting, this function
278  * becomes noop.
279  *
280  * CONTEXT:
281  * Must be called with @task->sighand->siglock held.
282  *
283  * RETURNS:
284  * %true if @mask is set, %false if made noop because @task was dying.
285  */
task_set_jobctl_pending(struct task_struct * task,unsigned long mask)286 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
287 {
288 	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
289 			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
290 	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
291 
292 	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
293 		return false;
294 
295 	if (mask & JOBCTL_STOP_SIGMASK)
296 		task->jobctl &= ~JOBCTL_STOP_SIGMASK;
297 
298 	task->jobctl |= mask;
299 	return true;
300 }
301 
302 /**
303  * task_clear_jobctl_trapping - clear jobctl trapping bit
304  * @task: target task
305  *
306  * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
307  * Clear it and wake up the ptracer.  Note that we don't need any further
308  * locking.  @task->siglock guarantees that @task->parent points to the
309  * ptracer.
310  *
311  * CONTEXT:
312  * Must be called with @task->sighand->siglock held.
313  */
task_clear_jobctl_trapping(struct task_struct * task)314 void task_clear_jobctl_trapping(struct task_struct *task)
315 {
316 	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
317 		task->jobctl &= ~JOBCTL_TRAPPING;
318 		smp_mb();	/* advised by wake_up_bit() */
319 		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
320 	}
321 }
322 
323 /**
324  * task_clear_jobctl_pending - clear jobctl pending bits
325  * @task: target task
326  * @mask: pending bits to clear
327  *
328  * Clear @mask from @task->jobctl.  @mask must be subset of
329  * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
330  * STOP bits are cleared together.
331  *
332  * If clearing of @mask leaves no stop or trap pending, this function calls
333  * task_clear_jobctl_trapping().
334  *
335  * CONTEXT:
336  * Must be called with @task->sighand->siglock held.
337  */
task_clear_jobctl_pending(struct task_struct * task,unsigned long mask)338 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
339 {
340 	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
341 
342 	if (mask & JOBCTL_STOP_PENDING)
343 		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
344 
345 	task->jobctl &= ~mask;
346 
347 	if (!(task->jobctl & JOBCTL_PENDING_MASK))
348 		task_clear_jobctl_trapping(task);
349 }
350 
351 /**
352  * task_participate_group_stop - participate in a group stop
353  * @task: task participating in a group stop
354  *
355  * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
356  * Group stop states are cleared and the group stop count is consumed if
357  * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
358  * stop, the appropriate `SIGNAL_*` flags are set.
359  *
360  * CONTEXT:
361  * Must be called with @task->sighand->siglock held.
362  *
363  * RETURNS:
364  * %true if group stop completion should be notified to the parent, %false
365  * otherwise.
366  */
task_participate_group_stop(struct task_struct * task)367 static bool task_participate_group_stop(struct task_struct *task)
368 {
369 	struct signal_struct *sig = task->signal;
370 	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
371 
372 	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
373 
374 	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
375 
376 	if (!consume)
377 		return false;
378 
379 	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
380 		sig->group_stop_count--;
381 
382 	/*
383 	 * Tell the caller to notify completion iff we are entering into a
384 	 * fresh group stop.  Read comment in do_signal_stop() for details.
385 	 */
386 	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
387 		signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
388 		return true;
389 	}
390 	return false;
391 }
392 
task_join_group_stop(struct task_struct * task)393 void task_join_group_stop(struct task_struct *task)
394 {
395 	unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
396 	struct signal_struct *sig = current->signal;
397 
398 	if (sig->group_stop_count) {
399 		sig->group_stop_count++;
400 		mask |= JOBCTL_STOP_CONSUME;
401 	} else if (!(sig->flags & SIGNAL_STOP_STOPPED))
402 		return;
403 
404 	/* Have the new thread join an on-going signal group stop */
405 	task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
406 }
407 
408 /*
409  * allocate a new signal queue record
410  * - this may be called without locks if and only if t == current, otherwise an
411  *   appropriate lock must be held to stop the target task from exiting
412  */
413 static struct sigqueue *
__sigqueue_alloc(int sig,struct task_struct * t,gfp_t gfp_flags,int override_rlimit,const unsigned int sigqueue_flags)414 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
415 		 int override_rlimit, const unsigned int sigqueue_flags)
416 {
417 	struct sigqueue *q = NULL;
418 	struct ucounts *ucounts = NULL;
419 	long sigpending;
420 
421 	/*
422 	 * Protect access to @t credentials. This can go away when all
423 	 * callers hold rcu read lock.
424 	 *
425 	 * NOTE! A pending signal will hold on to the user refcount,
426 	 * and we get/put the refcount only when the sigpending count
427 	 * changes from/to zero.
428 	 */
429 	rcu_read_lock();
430 	ucounts = task_ucounts(t);
431 	sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
432 	rcu_read_unlock();
433 	if (!sigpending)
434 		return NULL;
435 
436 	if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
437 		q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
438 	} else {
439 		print_dropped_signal(sig);
440 	}
441 
442 	if (unlikely(q == NULL)) {
443 		dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
444 	} else {
445 		INIT_LIST_HEAD(&q->list);
446 		q->flags = sigqueue_flags;
447 		q->ucounts = ucounts;
448 	}
449 	return q;
450 }
451 
__sigqueue_free(struct sigqueue * q)452 static void __sigqueue_free(struct sigqueue *q)
453 {
454 	if (q->flags & SIGQUEUE_PREALLOC)
455 		return;
456 	if (q->ucounts) {
457 		dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
458 		q->ucounts = NULL;
459 	}
460 	kmem_cache_free(sigqueue_cachep, q);
461 }
462 
flush_sigqueue(struct sigpending * queue)463 void flush_sigqueue(struct sigpending *queue)
464 {
465 	struct sigqueue *q;
466 
467 	sigemptyset(&queue->signal);
468 	while (!list_empty(&queue->list)) {
469 		q = list_entry(queue->list.next, struct sigqueue , list);
470 		list_del_init(&q->list);
471 		__sigqueue_free(q);
472 	}
473 }
474 
475 /*
476  * Flush all pending signals for this kthread.
477  */
flush_signals(struct task_struct * t)478 void flush_signals(struct task_struct *t)
479 {
480 	unsigned long flags;
481 
482 	spin_lock_irqsave(&t->sighand->siglock, flags);
483 	clear_tsk_thread_flag(t, TIF_SIGPENDING);
484 	flush_sigqueue(&t->pending);
485 	flush_sigqueue(&t->signal->shared_pending);
486 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
487 }
488 EXPORT_SYMBOL(flush_signals);
489 
490 #ifdef CONFIG_POSIX_TIMERS
__flush_itimer_signals(struct sigpending * pending)491 static void __flush_itimer_signals(struct sigpending *pending)
492 {
493 	sigset_t signal, retain;
494 	struct sigqueue *q, *n;
495 
496 	signal = pending->signal;
497 	sigemptyset(&retain);
498 
499 	list_for_each_entry_safe(q, n, &pending->list, list) {
500 		int sig = q->info.si_signo;
501 
502 		if (likely(q->info.si_code != SI_TIMER)) {
503 			sigaddset(&retain, sig);
504 		} else {
505 			sigdelset(&signal, sig);
506 			list_del_init(&q->list);
507 			__sigqueue_free(q);
508 		}
509 	}
510 
511 	sigorsets(&pending->signal, &signal, &retain);
512 }
513 
flush_itimer_signals(void)514 void flush_itimer_signals(void)
515 {
516 	struct task_struct *tsk = current;
517 	unsigned long flags;
518 
519 	spin_lock_irqsave(&tsk->sighand->siglock, flags);
520 	__flush_itimer_signals(&tsk->pending);
521 	__flush_itimer_signals(&tsk->signal->shared_pending);
522 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
523 }
524 #endif
525 
ignore_signals(struct task_struct * t)526 void ignore_signals(struct task_struct *t)
527 {
528 	int i;
529 
530 	for (i = 0; i < _NSIG; ++i)
531 		t->sighand->action[i].sa.sa_handler = SIG_IGN;
532 
533 	flush_signals(t);
534 }
535 
536 /*
537  * Flush all handlers for a task.
538  */
539 
540 void
flush_signal_handlers(struct task_struct * t,int force_default)541 flush_signal_handlers(struct task_struct *t, int force_default)
542 {
543 	int i;
544 	struct k_sigaction *ka = &t->sighand->action[0];
545 	for (i = _NSIG ; i != 0 ; i--) {
546 		if (force_default || ka->sa.sa_handler != SIG_IGN)
547 			ka->sa.sa_handler = SIG_DFL;
548 		ka->sa.sa_flags = 0;
549 #ifdef __ARCH_HAS_SA_RESTORER
550 		ka->sa.sa_restorer = NULL;
551 #endif
552 		sigemptyset(&ka->sa.sa_mask);
553 		ka++;
554 	}
555 }
556 
unhandled_signal(struct task_struct * tsk,int sig)557 bool unhandled_signal(struct task_struct *tsk, int sig)
558 {
559 	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
560 	if (is_global_init(tsk))
561 		return true;
562 
563 	if (handler != SIG_IGN && handler != SIG_DFL)
564 		return false;
565 
566 	/* If dying, we handle all new signals by ignoring them */
567 	if (fatal_signal_pending(tsk))
568 		return false;
569 
570 	/* if ptraced, let the tracer determine */
571 	return !tsk->ptrace;
572 }
573 
collect_signal(int sig,struct sigpending * list,kernel_siginfo_t * info,bool * resched_timer)574 static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
575 			   bool *resched_timer)
576 {
577 	struct sigqueue *q, *first = NULL;
578 
579 	/*
580 	 * Collect the siginfo appropriate to this signal.  Check if
581 	 * there is another siginfo for the same signal.
582 	*/
583 	list_for_each_entry(q, &list->list, list) {
584 		if (q->info.si_signo == sig) {
585 			if (first)
586 				goto still_pending;
587 			first = q;
588 		}
589 	}
590 
591 	sigdelset(&list->signal, sig);
592 
593 	if (first) {
594 still_pending:
595 		list_del_init(&first->list);
596 		copy_siginfo(info, &first->info);
597 
598 		*resched_timer =
599 			(first->flags & SIGQUEUE_PREALLOC) &&
600 			(info->si_code == SI_TIMER) &&
601 			(info->si_sys_private);
602 
603 		__sigqueue_free(first);
604 	} else {
605 		/*
606 		 * Ok, it wasn't in the queue.  This must be
607 		 * a fast-pathed signal or we must have been
608 		 * out of queue space.  So zero out the info.
609 		 */
610 		clear_siginfo(info);
611 		info->si_signo = sig;
612 		info->si_errno = 0;
613 		info->si_code = SI_USER;
614 		info->si_pid = 0;
615 		info->si_uid = 0;
616 	}
617 }
618 
__dequeue_signal(struct sigpending * pending,sigset_t * mask,kernel_siginfo_t * info,bool * resched_timer)619 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
620 			kernel_siginfo_t *info, bool *resched_timer)
621 {
622 	int sig = next_signal(pending, mask);
623 
624 	if (sig)
625 		collect_signal(sig, pending, info, resched_timer);
626 	return sig;
627 }
628 
629 /*
630  * Dequeue a signal and return the element to the caller, which is
631  * expected to free it.
632  *
633  * All callers have to hold the siglock.
634  */
dequeue_signal(struct task_struct * tsk,sigset_t * mask,kernel_siginfo_t * info,enum pid_type * type)635 int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
636 		   kernel_siginfo_t *info, enum pid_type *type)
637 {
638 	bool resched_timer = false;
639 	int signr;
640 
641 	/* We only dequeue private signals from ourselves, we don't let
642 	 * signalfd steal them
643 	 */
644 	*type = PIDTYPE_PID;
645 	signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
646 	if (!signr) {
647 		*type = PIDTYPE_TGID;
648 		signr = __dequeue_signal(&tsk->signal->shared_pending,
649 					 mask, info, &resched_timer);
650 #ifdef CONFIG_POSIX_TIMERS
651 		/*
652 		 * itimer signal ?
653 		 *
654 		 * itimers are process shared and we restart periodic
655 		 * itimers in the signal delivery path to prevent DoS
656 		 * attacks in the high resolution timer case. This is
657 		 * compliant with the old way of self-restarting
658 		 * itimers, as the SIGALRM is a legacy signal and only
659 		 * queued once. Changing the restart behaviour to
660 		 * restart the timer in the signal dequeue path is
661 		 * reducing the timer noise on heavy loaded !highres
662 		 * systems too.
663 		 */
664 		if (unlikely(signr == SIGALRM)) {
665 			struct hrtimer *tmr = &tsk->signal->real_timer;
666 
667 			if (!hrtimer_is_queued(tmr) &&
668 			    tsk->signal->it_real_incr != 0) {
669 				hrtimer_forward(tmr, tmr->base->get_time(),
670 						tsk->signal->it_real_incr);
671 				hrtimer_restart(tmr);
672 			}
673 		}
674 #endif
675 	}
676 
677 	recalc_sigpending();
678 	if (!signr)
679 		return 0;
680 
681 	if (unlikely(sig_kernel_stop(signr))) {
682 		/*
683 		 * Set a marker that we have dequeued a stop signal.  Our
684 		 * caller might release the siglock and then the pending
685 		 * stop signal it is about to process is no longer in the
686 		 * pending bitmasks, but must still be cleared by a SIGCONT
687 		 * (and overruled by a SIGKILL).  So those cases clear this
688 		 * shared flag after we've set it.  Note that this flag may
689 		 * remain set after the signal we return is ignored or
690 		 * handled.  That doesn't matter because its only purpose
691 		 * is to alert stop-signal processing code when another
692 		 * processor has come along and cleared the flag.
693 		 */
694 		current->jobctl |= JOBCTL_STOP_DEQUEUED;
695 	}
696 #ifdef CONFIG_POSIX_TIMERS
697 	if (resched_timer) {
698 		/*
699 		 * Release the siglock to ensure proper locking order
700 		 * of timer locks outside of siglocks.  Note, we leave
701 		 * irqs disabled here, since the posix-timers code is
702 		 * about to disable them again anyway.
703 		 */
704 		spin_unlock(&tsk->sighand->siglock);
705 		posixtimer_rearm(info);
706 		spin_lock(&tsk->sighand->siglock);
707 
708 		/* Don't expose the si_sys_private value to userspace */
709 		info->si_sys_private = 0;
710 	}
711 #endif
712 	return signr;
713 }
714 EXPORT_SYMBOL_GPL(dequeue_signal);
715 
dequeue_synchronous_signal(kernel_siginfo_t * info)716 static int dequeue_synchronous_signal(kernel_siginfo_t *info)
717 {
718 	struct task_struct *tsk = current;
719 	struct sigpending *pending = &tsk->pending;
720 	struct sigqueue *q, *sync = NULL;
721 
722 	/*
723 	 * Might a synchronous signal be in the queue?
724 	 */
725 	if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
726 		return 0;
727 
728 	/*
729 	 * Return the first synchronous signal in the queue.
730 	 */
731 	list_for_each_entry(q, &pending->list, list) {
732 		/* Synchronous signals have a positive si_code */
733 		if ((q->info.si_code > SI_USER) &&
734 		    (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
735 			sync = q;
736 			goto next;
737 		}
738 	}
739 	return 0;
740 next:
741 	/*
742 	 * Check if there is another siginfo for the same signal.
743 	 */
744 	list_for_each_entry_continue(q, &pending->list, list) {
745 		if (q->info.si_signo == sync->info.si_signo)
746 			goto still_pending;
747 	}
748 
749 	sigdelset(&pending->signal, sync->info.si_signo);
750 	recalc_sigpending();
751 still_pending:
752 	list_del_init(&sync->list);
753 	copy_siginfo(info, &sync->info);
754 	__sigqueue_free(sync);
755 	return info->si_signo;
756 }
757 
758 /*
759  * Tell a process that it has a new active signal..
760  *
761  * NOTE! we rely on the previous spin_lock to
762  * lock interrupts for us! We can only be called with
763  * "siglock" held, and the local interrupt must
764  * have been disabled when that got acquired!
765  *
766  * No need to set need_resched since signal event passing
767  * goes through ->blocked
768  */
signal_wake_up_state(struct task_struct * t,unsigned int state)769 void signal_wake_up_state(struct task_struct *t, unsigned int state)
770 {
771 	lockdep_assert_held(&t->sighand->siglock);
772 
773 	set_tsk_thread_flag(t, TIF_SIGPENDING);
774 
775 	/*
776 	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
777 	 * case. We don't check t->state here because there is a race with it
778 	 * executing another processor and just now entering stopped state.
779 	 * By using wake_up_state, we ensure the process will wake up and
780 	 * handle its death signal.
781 	 */
782 	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
783 		kick_process(t);
784 }
785 
786 /*
787  * Remove signals in mask from the pending set and queue.
788  * Returns 1 if any signals were found.
789  *
790  * All callers must be holding the siglock.
791  */
flush_sigqueue_mask(sigset_t * mask,struct sigpending * s)792 static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
793 {
794 	struct sigqueue *q, *n;
795 	sigset_t m;
796 
797 	sigandsets(&m, mask, &s->signal);
798 	if (sigisemptyset(&m))
799 		return;
800 
801 	sigandnsets(&s->signal, &s->signal, mask);
802 	list_for_each_entry_safe(q, n, &s->list, list) {
803 		if (sigismember(mask, q->info.si_signo)) {
804 			list_del_init(&q->list);
805 			__sigqueue_free(q);
806 		}
807 	}
808 }
809 
is_si_special(const struct kernel_siginfo * info)810 static inline int is_si_special(const struct kernel_siginfo *info)
811 {
812 	return info <= SEND_SIG_PRIV;
813 }
814 
si_fromuser(const struct kernel_siginfo * info)815 static inline bool si_fromuser(const struct kernel_siginfo *info)
816 {
817 	return info == SEND_SIG_NOINFO ||
818 		(!is_si_special(info) && SI_FROMUSER(info));
819 }
820 
821 /*
822  * called with RCU read lock from check_kill_permission()
823  */
kill_ok_by_cred(struct task_struct * t)824 static bool kill_ok_by_cred(struct task_struct *t)
825 {
826 	const struct cred *cred = current_cred();
827 	const struct cred *tcred = __task_cred(t);
828 
829 	return uid_eq(cred->euid, tcred->suid) ||
830 	       uid_eq(cred->euid, tcred->uid) ||
831 	       uid_eq(cred->uid, tcred->suid) ||
832 	       uid_eq(cred->uid, tcred->uid) ||
833 	       ns_capable(tcred->user_ns, CAP_KILL);
834 }
835 
836 /*
837  * Bad permissions for sending the signal
838  * - the caller must hold the RCU read lock
839  */
check_kill_permission(int sig,struct kernel_siginfo * info,struct task_struct * t)840 static int check_kill_permission(int sig, struct kernel_siginfo *info,
841 				 struct task_struct *t)
842 {
843 	struct pid *sid;
844 	int error;
845 
846 	if (!valid_signal(sig))
847 		return -EINVAL;
848 
849 	if (!si_fromuser(info))
850 		return 0;
851 
852 	error = audit_signal_info(sig, t); /* Let audit system see the signal */
853 	if (error)
854 		return error;
855 
856 	if (!same_thread_group(current, t) &&
857 	    !kill_ok_by_cred(t)) {
858 		switch (sig) {
859 		case SIGCONT:
860 			sid = task_session(t);
861 			/*
862 			 * We don't return the error if sid == NULL. The
863 			 * task was unhashed, the caller must notice this.
864 			 */
865 			if (!sid || sid == task_session(current))
866 				break;
867 			fallthrough;
868 		default:
869 			return -EPERM;
870 		}
871 	}
872 
873 	return security_task_kill(t, info, sig, NULL);
874 }
875 
876 /**
877  * ptrace_trap_notify - schedule trap to notify ptracer
878  * @t: tracee wanting to notify tracer
879  *
880  * This function schedules sticky ptrace trap which is cleared on the next
881  * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
882  * ptracer.
883  *
884  * If @t is running, STOP trap will be taken.  If trapped for STOP and
885  * ptracer is listening for events, tracee is woken up so that it can
886  * re-trap for the new event.  If trapped otherwise, STOP trap will be
887  * eventually taken without returning to userland after the existing traps
888  * are finished by PTRACE_CONT.
889  *
890  * CONTEXT:
891  * Must be called with @task->sighand->siglock held.
892  */
ptrace_trap_notify(struct task_struct * t)893 static void ptrace_trap_notify(struct task_struct *t)
894 {
895 	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
896 	lockdep_assert_held(&t->sighand->siglock);
897 
898 	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
899 	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
900 }
901 
902 /*
903  * Handle magic process-wide effects of stop/continue signals. Unlike
904  * the signal actions, these happen immediately at signal-generation
905  * time regardless of blocking, ignoring, or handling.  This does the
906  * actual continuing for SIGCONT, but not the actual stopping for stop
907  * signals. The process stop is done as a signal action for SIG_DFL.
908  *
909  * Returns true if the signal should be actually delivered, otherwise
910  * it should be dropped.
911  */
prepare_signal(int sig,struct task_struct * p,bool force)912 static bool prepare_signal(int sig, struct task_struct *p, bool force)
913 {
914 	struct signal_struct *signal = p->signal;
915 	struct task_struct *t;
916 	sigset_t flush;
917 
918 	if (signal->flags & SIGNAL_GROUP_EXIT) {
919 		if (signal->core_state)
920 			return sig == SIGKILL;
921 		/*
922 		 * The process is in the middle of dying, drop the signal.
923 		 */
924 		return false;
925 	} else if (sig_kernel_stop(sig)) {
926 		/*
927 		 * This is a stop signal.  Remove SIGCONT from all queues.
928 		 */
929 		siginitset(&flush, sigmask(SIGCONT));
930 		flush_sigqueue_mask(&flush, &signal->shared_pending);
931 		for_each_thread(p, t)
932 			flush_sigqueue_mask(&flush, &t->pending);
933 	} else if (sig == SIGCONT) {
934 		unsigned int why;
935 		/*
936 		 * Remove all stop signals from all queues, wake all threads.
937 		 */
938 		siginitset(&flush, SIG_KERNEL_STOP_MASK);
939 		flush_sigqueue_mask(&flush, &signal->shared_pending);
940 		for_each_thread(p, t) {
941 			flush_sigqueue_mask(&flush, &t->pending);
942 			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
943 			if (likely(!(t->ptrace & PT_SEIZED))) {
944 				t->jobctl &= ~JOBCTL_STOPPED;
945 				wake_up_state(t, __TASK_STOPPED);
946 			} else
947 				ptrace_trap_notify(t);
948 		}
949 
950 		/*
951 		 * Notify the parent with CLD_CONTINUED if we were stopped.
952 		 *
953 		 * If we were in the middle of a group stop, we pretend it
954 		 * was already finished, and then continued. Since SIGCHLD
955 		 * doesn't queue we report only CLD_STOPPED, as if the next
956 		 * CLD_CONTINUED was dropped.
957 		 */
958 		why = 0;
959 		if (signal->flags & SIGNAL_STOP_STOPPED)
960 			why |= SIGNAL_CLD_CONTINUED;
961 		else if (signal->group_stop_count)
962 			why |= SIGNAL_CLD_STOPPED;
963 
964 		if (why) {
965 			/*
966 			 * The first thread which returns from do_signal_stop()
967 			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
968 			 * notify its parent. See get_signal().
969 			 */
970 			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
971 			signal->group_stop_count = 0;
972 			signal->group_exit_code = 0;
973 		}
974 	}
975 
976 	return !sig_ignored(p, sig, force);
977 }
978 
979 /*
980  * Test if P wants to take SIG.  After we've checked all threads with this,
981  * it's equivalent to finding no threads not blocking SIG.  Any threads not
982  * blocking SIG were ruled out because they are not running and already
983  * have pending signals.  Such threads will dequeue from the shared queue
984  * as soon as they're available, so putting the signal on the shared queue
985  * will be equivalent to sending it to one such thread.
986  */
wants_signal(int sig,struct task_struct * p)987 static inline bool wants_signal(int sig, struct task_struct *p)
988 {
989 	if (sigismember(&p->blocked, sig))
990 		return false;
991 
992 	if (p->flags & PF_EXITING)
993 		return false;
994 
995 	if (sig == SIGKILL)
996 		return true;
997 
998 	if (task_is_stopped_or_traced(p))
999 		return false;
1000 
1001 	return task_curr(p) || !task_sigpending(p);
1002 }
1003 
complete_signal(int sig,struct task_struct * p,enum pid_type type)1004 static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
1005 {
1006 	struct signal_struct *signal = p->signal;
1007 	struct task_struct *t;
1008 
1009 	/*
1010 	 * Now find a thread we can wake up to take the signal off the queue.
1011 	 *
1012 	 * Try the suggested task first (may or may not be the main thread).
1013 	 */
1014 	if (wants_signal(sig, p))
1015 		t = p;
1016 	else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1017 		/*
1018 		 * There is just one thread and it does not need to be woken.
1019 		 * It will dequeue unblocked signals before it runs again.
1020 		 */
1021 		return;
1022 	else {
1023 		/*
1024 		 * Otherwise try to find a suitable thread.
1025 		 */
1026 		t = signal->curr_target;
1027 		while (!wants_signal(sig, t)) {
1028 			t = next_thread(t);
1029 			if (t == signal->curr_target)
1030 				/*
1031 				 * No thread needs to be woken.
1032 				 * Any eligible threads will see
1033 				 * the signal in the queue soon.
1034 				 */
1035 				return;
1036 		}
1037 		signal->curr_target = t;
1038 	}
1039 
1040 	/*
1041 	 * Found a killable thread.  If the signal will be fatal,
1042 	 * then start taking the whole group down immediately.
1043 	 */
1044 	if (sig_fatal(p, sig) &&
1045 	    (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1046 	    !sigismember(&t->real_blocked, sig) &&
1047 	    (sig == SIGKILL || !p->ptrace)) {
1048 		/*
1049 		 * This signal will be fatal to the whole group.
1050 		 */
1051 		if (!sig_kernel_coredump(sig)) {
1052 			/*
1053 			 * Start a group exit and wake everybody up.
1054 			 * This way we don't have other threads
1055 			 * running and doing things after a slower
1056 			 * thread has the fatal signal pending.
1057 			 */
1058 			signal->flags = SIGNAL_GROUP_EXIT;
1059 			signal->group_exit_code = sig;
1060 			signal->group_stop_count = 0;
1061 			t = p;
1062 			do {
1063 				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1064 				sigaddset(&t->pending.signal, SIGKILL);
1065 				signal_wake_up(t, 1);
1066 			} while_each_thread(p, t);
1067 			return;
1068 		}
1069 	}
1070 
1071 	/*
1072 	 * The signal is already in the shared-pending queue.
1073 	 * Tell the chosen thread to wake up and dequeue it.
1074 	 */
1075 	signal_wake_up(t, sig == SIGKILL);
1076 	return;
1077 }
1078 
legacy_queue(struct sigpending * signals,int sig)1079 static inline bool legacy_queue(struct sigpending *signals, int sig)
1080 {
1081 	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1082 }
1083 
__send_signal_locked(int sig,struct kernel_siginfo * info,struct task_struct * t,enum pid_type type,bool force)1084 static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1085 				struct task_struct *t, enum pid_type type, bool force)
1086 {
1087 	struct sigpending *pending;
1088 	struct sigqueue *q;
1089 	int override_rlimit;
1090 	int ret = 0, result;
1091 
1092 	lockdep_assert_held(&t->sighand->siglock);
1093 
1094 	result = TRACE_SIGNAL_IGNORED;
1095 	if (!prepare_signal(sig, t, force))
1096 		goto ret;
1097 
1098 	pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1099 	/*
1100 	 * Short-circuit ignored signals and support queuing
1101 	 * exactly one non-rt signal, so that we can get more
1102 	 * detailed information about the cause of the signal.
1103 	 */
1104 	result = TRACE_SIGNAL_ALREADY_PENDING;
1105 	if (legacy_queue(pending, sig))
1106 		goto ret;
1107 
1108 	result = TRACE_SIGNAL_DELIVERED;
1109 	/*
1110 	 * Skip useless siginfo allocation for SIGKILL and kernel threads.
1111 	 */
1112 	if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1113 		goto out_set;
1114 
1115 	/*
1116 	 * Real-time signals must be queued if sent by sigqueue, or
1117 	 * some other real-time mechanism.  It is implementation
1118 	 * defined whether kill() does so.  We attempt to do so, on
1119 	 * the principle of least surprise, but since kill is not
1120 	 * allowed to fail with EAGAIN when low on memory we just
1121 	 * make sure at least one signal gets delivered and don't
1122 	 * pass on the info struct.
1123 	 */
1124 	if (sig < SIGRTMIN)
1125 		override_rlimit = (is_si_special(info) || info->si_code >= 0);
1126 	else
1127 		override_rlimit = 0;
1128 
1129 	q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1130 
1131 	if (q) {
1132 		list_add_tail(&q->list, &pending->list);
1133 		switch ((unsigned long) info) {
1134 		case (unsigned long) SEND_SIG_NOINFO:
1135 			clear_siginfo(&q->info);
1136 			q->info.si_signo = sig;
1137 			q->info.si_errno = 0;
1138 			q->info.si_code = SI_USER;
1139 			q->info.si_pid = task_tgid_nr_ns(current,
1140 							task_active_pid_ns(t));
1141 			rcu_read_lock();
1142 			q->info.si_uid =
1143 				from_kuid_munged(task_cred_xxx(t, user_ns),
1144 						 current_uid());
1145 			rcu_read_unlock();
1146 			break;
1147 		case (unsigned long) SEND_SIG_PRIV:
1148 			clear_siginfo(&q->info);
1149 			q->info.si_signo = sig;
1150 			q->info.si_errno = 0;
1151 			q->info.si_code = SI_KERNEL;
1152 			q->info.si_pid = 0;
1153 			q->info.si_uid = 0;
1154 			break;
1155 		default:
1156 			copy_siginfo(&q->info, info);
1157 			break;
1158 		}
1159 	} else if (!is_si_special(info) &&
1160 		   sig >= SIGRTMIN && info->si_code != SI_USER) {
1161 		/*
1162 		 * Queue overflow, abort.  We may abort if the
1163 		 * signal was rt and sent by user using something
1164 		 * other than kill().
1165 		 */
1166 		result = TRACE_SIGNAL_OVERFLOW_FAIL;
1167 		ret = -EAGAIN;
1168 		goto ret;
1169 	} else {
1170 		/*
1171 		 * This is a silent loss of information.  We still
1172 		 * send the signal, but the *info bits are lost.
1173 		 */
1174 		result = TRACE_SIGNAL_LOSE_INFO;
1175 	}
1176 
1177 out_set:
1178 	signalfd_notify(t, sig);
1179 	sigaddset(&pending->signal, sig);
1180 
1181 	/* Let multiprocess signals appear after on-going forks */
1182 	if (type > PIDTYPE_TGID) {
1183 		struct multiprocess_signals *delayed;
1184 		hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1185 			sigset_t *signal = &delayed->signal;
1186 			/* Can't queue both a stop and a continue signal */
1187 			if (sig == SIGCONT)
1188 				sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1189 			else if (sig_kernel_stop(sig))
1190 				sigdelset(signal, SIGCONT);
1191 			sigaddset(signal, sig);
1192 		}
1193 	}
1194 
1195 	complete_signal(sig, t, type);
1196 ret:
1197 	trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1198 	return ret;
1199 }
1200 
has_si_pid_and_uid(struct kernel_siginfo * info)1201 static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1202 {
1203 	bool ret = false;
1204 	switch (siginfo_layout(info->si_signo, info->si_code)) {
1205 	case SIL_KILL:
1206 	case SIL_CHLD:
1207 	case SIL_RT:
1208 		ret = true;
1209 		break;
1210 	case SIL_TIMER:
1211 	case SIL_POLL:
1212 	case SIL_FAULT:
1213 	case SIL_FAULT_TRAPNO:
1214 	case SIL_FAULT_MCEERR:
1215 	case SIL_FAULT_BNDERR:
1216 	case SIL_FAULT_PKUERR:
1217 	case SIL_FAULT_PERF_EVENT:
1218 	case SIL_SYS:
1219 		ret = false;
1220 		break;
1221 	}
1222 	return ret;
1223 }
1224 
send_signal_locked(int sig,struct kernel_siginfo * info,struct task_struct * t,enum pid_type type)1225 int send_signal_locked(int sig, struct kernel_siginfo *info,
1226 		       struct task_struct *t, enum pid_type type)
1227 {
1228 	/* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1229 	bool force = false;
1230 
1231 	if (info == SEND_SIG_NOINFO) {
1232 		/* Force if sent from an ancestor pid namespace */
1233 		force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1234 	} else if (info == SEND_SIG_PRIV) {
1235 		/* Don't ignore kernel generated signals */
1236 		force = true;
1237 	} else if (has_si_pid_and_uid(info)) {
1238 		/* SIGKILL and SIGSTOP is special or has ids */
1239 		struct user_namespace *t_user_ns;
1240 
1241 		rcu_read_lock();
1242 		t_user_ns = task_cred_xxx(t, user_ns);
1243 		if (current_user_ns() != t_user_ns) {
1244 			kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1245 			info->si_uid = from_kuid_munged(t_user_ns, uid);
1246 		}
1247 		rcu_read_unlock();
1248 
1249 		/* A kernel generated signal? */
1250 		force = (info->si_code == SI_KERNEL);
1251 
1252 		/* From an ancestor pid namespace? */
1253 		if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1254 			info->si_pid = 0;
1255 			force = true;
1256 		}
1257 	}
1258 	return __send_signal_locked(sig, info, t, type, force);
1259 }
1260 
print_fatal_signal(int signr)1261 static void print_fatal_signal(int signr)
1262 {
1263 	struct pt_regs *regs = task_pt_regs(current);
1264 	struct file *exe_file;
1265 
1266 	exe_file = get_task_exe_file(current);
1267 	if (exe_file) {
1268 		pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1269 			exe_file, current->comm, signr);
1270 		fput(exe_file);
1271 	} else {
1272 		pr_info("%s: potentially unexpected fatal signal %d.\n",
1273 			current->comm, signr);
1274 	}
1275 
1276 #if defined(__i386__) && !defined(__arch_um__)
1277 	pr_info("code at %08lx: ", regs->ip);
1278 	{
1279 		int i;
1280 		for (i = 0; i < 16; i++) {
1281 			unsigned char insn;
1282 
1283 			if (get_user(insn, (unsigned char *)(regs->ip + i)))
1284 				break;
1285 			pr_cont("%02x ", insn);
1286 		}
1287 	}
1288 	pr_cont("\n");
1289 #endif
1290 	preempt_disable();
1291 	show_regs(regs);
1292 	preempt_enable();
1293 }
1294 
setup_print_fatal_signals(char * str)1295 static int __init setup_print_fatal_signals(char *str)
1296 {
1297 	get_option (&str, &print_fatal_signals);
1298 
1299 	return 1;
1300 }
1301 
1302 __setup("print-fatal-signals=", setup_print_fatal_signals);
1303 
do_send_sig_info(int sig,struct kernel_siginfo * info,struct task_struct * p,enum pid_type type)1304 int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1305 			enum pid_type type)
1306 {
1307 	unsigned long flags;
1308 	int ret = -ESRCH;
1309 
1310 	if (lock_task_sighand(p, &flags)) {
1311 		ret = send_signal_locked(sig, info, p, type);
1312 		unlock_task_sighand(p, &flags);
1313 	}
1314 
1315 	return ret;
1316 }
1317 
1318 enum sig_handler {
1319 	HANDLER_CURRENT, /* If reachable use the current handler */
1320 	HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1321 	HANDLER_EXIT,	 /* Only visible as the process exit code */
1322 };
1323 
1324 /*
1325  * Force a signal that the process can't ignore: if necessary
1326  * we unblock the signal and change any SIG_IGN to SIG_DFL.
1327  *
1328  * Note: If we unblock the signal, we always reset it to SIG_DFL,
1329  * since we do not want to have a signal handler that was blocked
1330  * be invoked when user space had explicitly blocked it.
1331  *
1332  * We don't want to have recursive SIGSEGV's etc, for example,
1333  * that is why we also clear SIGNAL_UNKILLABLE.
1334  */
1335 static int
force_sig_info_to_task(struct kernel_siginfo * info,struct task_struct * t,enum sig_handler handler)1336 force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1337 	enum sig_handler handler)
1338 {
1339 	unsigned long int flags;
1340 	int ret, blocked, ignored;
1341 	struct k_sigaction *action;
1342 	int sig = info->si_signo;
1343 
1344 	spin_lock_irqsave(&t->sighand->siglock, flags);
1345 	action = &t->sighand->action[sig-1];
1346 	ignored = action->sa.sa_handler == SIG_IGN;
1347 	blocked = sigismember(&t->blocked, sig);
1348 	if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1349 		action->sa.sa_handler = SIG_DFL;
1350 		if (handler == HANDLER_EXIT)
1351 			action->sa.sa_flags |= SA_IMMUTABLE;
1352 		if (blocked) {
1353 			sigdelset(&t->blocked, sig);
1354 			recalc_sigpending_and_wake(t);
1355 		}
1356 	}
1357 	/*
1358 	 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1359 	 * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1360 	 */
1361 	if (action->sa.sa_handler == SIG_DFL &&
1362 	    (!t->ptrace || (handler == HANDLER_EXIT)))
1363 		t->signal->flags &= ~SIGNAL_UNKILLABLE;
1364 	ret = send_signal_locked(sig, info, t, PIDTYPE_PID);
1365 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
1366 
1367 	return ret;
1368 }
1369 
force_sig_info(struct kernel_siginfo * info)1370 int force_sig_info(struct kernel_siginfo *info)
1371 {
1372 	return force_sig_info_to_task(info, current, HANDLER_CURRENT);
1373 }
1374 
1375 /*
1376  * Nuke all other threads in the group.
1377  */
zap_other_threads(struct task_struct * p)1378 int zap_other_threads(struct task_struct *p)
1379 {
1380 	struct task_struct *t = p;
1381 	int count = 0;
1382 
1383 	p->signal->group_stop_count = 0;
1384 
1385 	while_each_thread(p, t) {
1386 		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1387 		/* Don't require de_thread to wait for the vhost_worker */
1388 		if ((t->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)
1389 			count++;
1390 
1391 		/* Don't bother with already dead threads */
1392 		if (t->exit_state)
1393 			continue;
1394 		sigaddset(&t->pending.signal, SIGKILL);
1395 		signal_wake_up(t, 1);
1396 	}
1397 
1398 	return count;
1399 }
1400 
__lock_task_sighand(struct task_struct * tsk,unsigned long * flags)1401 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1402 					   unsigned long *flags)
1403 {
1404 	struct sighand_struct *sighand;
1405 
1406 	rcu_read_lock();
1407 	for (;;) {
1408 		sighand = rcu_dereference(tsk->sighand);
1409 		if (unlikely(sighand == NULL))
1410 			break;
1411 
1412 		/*
1413 		 * This sighand can be already freed and even reused, but
1414 		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1415 		 * initializes ->siglock: this slab can't go away, it has
1416 		 * the same object type, ->siglock can't be reinitialized.
1417 		 *
1418 		 * We need to ensure that tsk->sighand is still the same
1419 		 * after we take the lock, we can race with de_thread() or
1420 		 * __exit_signal(). In the latter case the next iteration
1421 		 * must see ->sighand == NULL.
1422 		 */
1423 		spin_lock_irqsave(&sighand->siglock, *flags);
1424 		if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1425 			break;
1426 		spin_unlock_irqrestore(&sighand->siglock, *flags);
1427 	}
1428 	rcu_read_unlock();
1429 
1430 	return sighand;
1431 }
1432 
1433 #ifdef CONFIG_LOCKDEP
lockdep_assert_task_sighand_held(struct task_struct * task)1434 void lockdep_assert_task_sighand_held(struct task_struct *task)
1435 {
1436 	struct sighand_struct *sighand;
1437 
1438 	rcu_read_lock();
1439 	sighand = rcu_dereference(task->sighand);
1440 	if (sighand)
1441 		lockdep_assert_held(&sighand->siglock);
1442 	else
1443 		WARN_ON_ONCE(1);
1444 	rcu_read_unlock();
1445 }
1446 #endif
1447 
1448 /*
1449  * send signal info to all the members of a group
1450  */
group_send_sig_info(int sig,struct kernel_siginfo * info,struct task_struct * p,enum pid_type type)1451 int group_send_sig_info(int sig, struct kernel_siginfo *info,
1452 			struct task_struct *p, enum pid_type type)
1453 {
1454 	int ret;
1455 
1456 	rcu_read_lock();
1457 	ret = check_kill_permission(sig, info, p);
1458 	rcu_read_unlock();
1459 
1460 	if (!ret && sig)
1461 		ret = do_send_sig_info(sig, info, p, type);
1462 
1463 	return ret;
1464 }
1465 
1466 /*
1467  * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1468  * control characters do (^C, ^Z etc)
1469  * - the caller must hold at least a readlock on tasklist_lock
1470  */
__kill_pgrp_info(int sig,struct kernel_siginfo * info,struct pid * pgrp)1471 int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1472 {
1473 	struct task_struct *p = NULL;
1474 	int retval, success;
1475 
1476 	success = 0;
1477 	retval = -ESRCH;
1478 	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1479 		int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1480 		success |= !err;
1481 		retval = err;
1482 	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1483 	return success ? 0 : retval;
1484 }
1485 
kill_pid_info(int sig,struct kernel_siginfo * info,struct pid * pid)1486 int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1487 {
1488 	int error = -ESRCH;
1489 	struct task_struct *p;
1490 
1491 	for (;;) {
1492 		rcu_read_lock();
1493 		p = pid_task(pid, PIDTYPE_PID);
1494 		if (p)
1495 			error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1496 		rcu_read_unlock();
1497 		if (likely(!p || error != -ESRCH))
1498 			return error;
1499 
1500 		/*
1501 		 * The task was unhashed in between, try again.  If it
1502 		 * is dead, pid_task() will return NULL, if we race with
1503 		 * de_thread() it will find the new leader.
1504 		 */
1505 	}
1506 }
1507 
kill_proc_info(int sig,struct kernel_siginfo * info,pid_t pid)1508 static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1509 {
1510 	int error;
1511 	rcu_read_lock();
1512 	error = kill_pid_info(sig, info, find_vpid(pid));
1513 	rcu_read_unlock();
1514 	return error;
1515 }
1516 
kill_as_cred_perm(const struct cred * cred,struct task_struct * target)1517 static inline bool kill_as_cred_perm(const struct cred *cred,
1518 				     struct task_struct *target)
1519 {
1520 	const struct cred *pcred = __task_cred(target);
1521 
1522 	return uid_eq(cred->euid, pcred->suid) ||
1523 	       uid_eq(cred->euid, pcred->uid) ||
1524 	       uid_eq(cred->uid, pcred->suid) ||
1525 	       uid_eq(cred->uid, pcred->uid);
1526 }
1527 
1528 /*
1529  * The usb asyncio usage of siginfo is wrong.  The glibc support
1530  * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1531  * AKA after the generic fields:
1532  *	kernel_pid_t	si_pid;
1533  *	kernel_uid32_t	si_uid;
1534  *	sigval_t	si_value;
1535  *
1536  * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1537  * after the generic fields is:
1538  *	void __user 	*si_addr;
1539  *
1540  * This is a practical problem when there is a 64bit big endian kernel
1541  * and a 32bit userspace.  As the 32bit address will encoded in the low
1542  * 32bits of the pointer.  Those low 32bits will be stored at higher
1543  * address than appear in a 32 bit pointer.  So userspace will not
1544  * see the address it was expecting for it's completions.
1545  *
1546  * There is nothing in the encoding that can allow
1547  * copy_siginfo_to_user32 to detect this confusion of formats, so
1548  * handle this by requiring the caller of kill_pid_usb_asyncio to
1549  * notice when this situration takes place and to store the 32bit
1550  * pointer in sival_int, instead of sival_addr of the sigval_t addr
1551  * parameter.
1552  */
kill_pid_usb_asyncio(int sig,int errno,sigval_t addr,struct pid * pid,const struct cred * cred)1553 int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1554 			 struct pid *pid, const struct cred *cred)
1555 {
1556 	struct kernel_siginfo info;
1557 	struct task_struct *p;
1558 	unsigned long flags;
1559 	int ret = -EINVAL;
1560 
1561 	if (!valid_signal(sig))
1562 		return ret;
1563 
1564 	clear_siginfo(&info);
1565 	info.si_signo = sig;
1566 	info.si_errno = errno;
1567 	info.si_code = SI_ASYNCIO;
1568 	*((sigval_t *)&info.si_pid) = addr;
1569 
1570 	rcu_read_lock();
1571 	p = pid_task(pid, PIDTYPE_PID);
1572 	if (!p) {
1573 		ret = -ESRCH;
1574 		goto out_unlock;
1575 	}
1576 	if (!kill_as_cred_perm(cred, p)) {
1577 		ret = -EPERM;
1578 		goto out_unlock;
1579 	}
1580 	ret = security_task_kill(p, &info, sig, cred);
1581 	if (ret)
1582 		goto out_unlock;
1583 
1584 	if (sig) {
1585 		if (lock_task_sighand(p, &flags)) {
1586 			ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false);
1587 			unlock_task_sighand(p, &flags);
1588 		} else
1589 			ret = -ESRCH;
1590 	}
1591 out_unlock:
1592 	rcu_read_unlock();
1593 	return ret;
1594 }
1595 EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1596 
1597 /*
1598  * kill_something_info() interprets pid in interesting ways just like kill(2).
1599  *
1600  * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1601  * is probably wrong.  Should make it like BSD or SYSV.
1602  */
1603 
kill_something_info(int sig,struct kernel_siginfo * info,pid_t pid)1604 static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1605 {
1606 	int ret;
1607 
1608 	if (pid > 0)
1609 		return kill_proc_info(sig, info, pid);
1610 
1611 	/* -INT_MIN is undefined.  Exclude this case to avoid a UBSAN warning */
1612 	if (pid == INT_MIN)
1613 		return -ESRCH;
1614 
1615 	read_lock(&tasklist_lock);
1616 	if (pid != -1) {
1617 		ret = __kill_pgrp_info(sig, info,
1618 				pid ? find_vpid(-pid) : task_pgrp(current));
1619 	} else {
1620 		int retval = 0, count = 0;
1621 		struct task_struct * p;
1622 
1623 		for_each_process(p) {
1624 			if (task_pid_vnr(p) > 1 &&
1625 					!same_thread_group(p, current)) {
1626 				int err = group_send_sig_info(sig, info, p,
1627 							      PIDTYPE_MAX);
1628 				++count;
1629 				if (err != -EPERM)
1630 					retval = err;
1631 			}
1632 		}
1633 		ret = count ? retval : -ESRCH;
1634 	}
1635 	read_unlock(&tasklist_lock);
1636 
1637 	return ret;
1638 }
1639 
1640 /*
1641  * These are for backward compatibility with the rest of the kernel source.
1642  */
1643 
send_sig_info(int sig,struct kernel_siginfo * info,struct task_struct * p)1644 int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1645 {
1646 	/*
1647 	 * Make sure legacy kernel users don't send in bad values
1648 	 * (normal paths check this in check_kill_permission).
1649 	 */
1650 	if (!valid_signal(sig))
1651 		return -EINVAL;
1652 
1653 	return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1654 }
1655 EXPORT_SYMBOL(send_sig_info);
1656 
1657 #define __si_special(priv) \
1658 	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1659 
1660 int
send_sig(int sig,struct task_struct * p,int priv)1661 send_sig(int sig, struct task_struct *p, int priv)
1662 {
1663 	return send_sig_info(sig, __si_special(priv), p);
1664 }
1665 EXPORT_SYMBOL(send_sig);
1666 
force_sig(int sig)1667 void force_sig(int sig)
1668 {
1669 	struct kernel_siginfo info;
1670 
1671 	clear_siginfo(&info);
1672 	info.si_signo = sig;
1673 	info.si_errno = 0;
1674 	info.si_code = SI_KERNEL;
1675 	info.si_pid = 0;
1676 	info.si_uid = 0;
1677 	force_sig_info(&info);
1678 }
1679 EXPORT_SYMBOL(force_sig);
1680 
force_fatal_sig(int sig)1681 void force_fatal_sig(int sig)
1682 {
1683 	struct kernel_siginfo info;
1684 
1685 	clear_siginfo(&info);
1686 	info.si_signo = sig;
1687 	info.si_errno = 0;
1688 	info.si_code = SI_KERNEL;
1689 	info.si_pid = 0;
1690 	info.si_uid = 0;
1691 	force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
1692 }
1693 
force_exit_sig(int sig)1694 void force_exit_sig(int sig)
1695 {
1696 	struct kernel_siginfo info;
1697 
1698 	clear_siginfo(&info);
1699 	info.si_signo = sig;
1700 	info.si_errno = 0;
1701 	info.si_code = SI_KERNEL;
1702 	info.si_pid = 0;
1703 	info.si_uid = 0;
1704 	force_sig_info_to_task(&info, current, HANDLER_EXIT);
1705 }
1706 
1707 /*
1708  * When things go south during signal handling, we
1709  * will force a SIGSEGV. And if the signal that caused
1710  * the problem was already a SIGSEGV, we'll want to
1711  * make sure we don't even try to deliver the signal..
1712  */
force_sigsegv(int sig)1713 void force_sigsegv(int sig)
1714 {
1715 	if (sig == SIGSEGV)
1716 		force_fatal_sig(SIGSEGV);
1717 	else
1718 		force_sig(SIGSEGV);
1719 }
1720 
force_sig_fault_to_task(int sig,int code,void __user * addr ___ARCH_SI_IA64 (int imm,unsigned int flags,unsigned long isr),struct task_struct * t)1721 int force_sig_fault_to_task(int sig, int code, void __user *addr
1722 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1723 	, struct task_struct *t)
1724 {
1725 	struct kernel_siginfo info;
1726 
1727 	clear_siginfo(&info);
1728 	info.si_signo = sig;
1729 	info.si_errno = 0;
1730 	info.si_code  = code;
1731 	info.si_addr  = addr;
1732 #ifdef __ia64__
1733 	info.si_imm = imm;
1734 	info.si_flags = flags;
1735 	info.si_isr = isr;
1736 #endif
1737 	return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
1738 }
1739 
force_sig_fault(int sig,int code,void __user * addr ___ARCH_SI_IA64 (int imm,unsigned int flags,unsigned long isr))1740 int force_sig_fault(int sig, int code, void __user *addr
1741 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1742 {
1743 	return force_sig_fault_to_task(sig, code, addr
1744 				       ___ARCH_SI_IA64(imm, flags, isr), current);
1745 }
1746 
send_sig_fault(int sig,int code,void __user * addr ___ARCH_SI_IA64 (int imm,unsigned int flags,unsigned long isr),struct task_struct * t)1747 int send_sig_fault(int sig, int code, void __user *addr
1748 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1749 	, struct task_struct *t)
1750 {
1751 	struct kernel_siginfo info;
1752 
1753 	clear_siginfo(&info);
1754 	info.si_signo = sig;
1755 	info.si_errno = 0;
1756 	info.si_code  = code;
1757 	info.si_addr  = addr;
1758 #ifdef __ia64__
1759 	info.si_imm = imm;
1760 	info.si_flags = flags;
1761 	info.si_isr = isr;
1762 #endif
1763 	return send_sig_info(info.si_signo, &info, t);
1764 }
1765 
force_sig_mceerr(int code,void __user * addr,short lsb)1766 int force_sig_mceerr(int code, void __user *addr, short lsb)
1767 {
1768 	struct kernel_siginfo info;
1769 
1770 	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1771 	clear_siginfo(&info);
1772 	info.si_signo = SIGBUS;
1773 	info.si_errno = 0;
1774 	info.si_code = code;
1775 	info.si_addr = addr;
1776 	info.si_addr_lsb = lsb;
1777 	return force_sig_info(&info);
1778 }
1779 
send_sig_mceerr(int code,void __user * addr,short lsb,struct task_struct * t)1780 int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1781 {
1782 	struct kernel_siginfo info;
1783 
1784 	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1785 	clear_siginfo(&info);
1786 	info.si_signo = SIGBUS;
1787 	info.si_errno = 0;
1788 	info.si_code = code;
1789 	info.si_addr = addr;
1790 	info.si_addr_lsb = lsb;
1791 	return send_sig_info(info.si_signo, &info, t);
1792 }
1793 EXPORT_SYMBOL(send_sig_mceerr);
1794 
force_sig_bnderr(void __user * addr,void __user * lower,void __user * upper)1795 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1796 {
1797 	struct kernel_siginfo info;
1798 
1799 	clear_siginfo(&info);
1800 	info.si_signo = SIGSEGV;
1801 	info.si_errno = 0;
1802 	info.si_code  = SEGV_BNDERR;
1803 	info.si_addr  = addr;
1804 	info.si_lower = lower;
1805 	info.si_upper = upper;
1806 	return force_sig_info(&info);
1807 }
1808 
1809 #ifdef SEGV_PKUERR
force_sig_pkuerr(void __user * addr,u32 pkey)1810 int force_sig_pkuerr(void __user *addr, u32 pkey)
1811 {
1812 	struct kernel_siginfo info;
1813 
1814 	clear_siginfo(&info);
1815 	info.si_signo = SIGSEGV;
1816 	info.si_errno = 0;
1817 	info.si_code  = SEGV_PKUERR;
1818 	info.si_addr  = addr;
1819 	info.si_pkey  = pkey;
1820 	return force_sig_info(&info);
1821 }
1822 #endif
1823 
send_sig_perf(void __user * addr,u32 type,u64 sig_data)1824 int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1825 {
1826 	struct kernel_siginfo info;
1827 
1828 	clear_siginfo(&info);
1829 	info.si_signo     = SIGTRAP;
1830 	info.si_errno     = 0;
1831 	info.si_code      = TRAP_PERF;
1832 	info.si_addr      = addr;
1833 	info.si_perf_data = sig_data;
1834 	info.si_perf_type = type;
1835 
1836 	/*
1837 	 * Signals generated by perf events should not terminate the whole
1838 	 * process if SIGTRAP is blocked, however, delivering the signal
1839 	 * asynchronously is better than not delivering at all. But tell user
1840 	 * space if the signal was asynchronous, so it can clearly be
1841 	 * distinguished from normal synchronous ones.
1842 	 */
1843 	info.si_perf_flags = sigismember(&current->blocked, info.si_signo) ?
1844 				     TRAP_PERF_FLAG_ASYNC :
1845 				     0;
1846 
1847 	return send_sig_info(info.si_signo, &info, current);
1848 }
1849 
1850 /**
1851  * force_sig_seccomp - signals the task to allow in-process syscall emulation
1852  * @syscall: syscall number to send to userland
1853  * @reason: filter-supplied reason code to send to userland (via si_errno)
1854  * @force_coredump: true to trigger a coredump
1855  *
1856  * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1857  */
force_sig_seccomp(int syscall,int reason,bool force_coredump)1858 int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1859 {
1860 	struct kernel_siginfo info;
1861 
1862 	clear_siginfo(&info);
1863 	info.si_signo = SIGSYS;
1864 	info.si_code = SYS_SECCOMP;
1865 	info.si_call_addr = (void __user *)KSTK_EIP(current);
1866 	info.si_errno = reason;
1867 	info.si_arch = syscall_get_arch(current);
1868 	info.si_syscall = syscall;
1869 	return force_sig_info_to_task(&info, current,
1870 		force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1871 }
1872 
1873 /* For the crazy architectures that include trap information in
1874  * the errno field, instead of an actual errno value.
1875  */
force_sig_ptrace_errno_trap(int errno,void __user * addr)1876 int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1877 {
1878 	struct kernel_siginfo info;
1879 
1880 	clear_siginfo(&info);
1881 	info.si_signo = SIGTRAP;
1882 	info.si_errno = errno;
1883 	info.si_code  = TRAP_HWBKPT;
1884 	info.si_addr  = addr;
1885 	return force_sig_info(&info);
1886 }
1887 
1888 /* For the rare architectures that include trap information using
1889  * si_trapno.
1890  */
force_sig_fault_trapno(int sig,int code,void __user * addr,int trapno)1891 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1892 {
1893 	struct kernel_siginfo info;
1894 
1895 	clear_siginfo(&info);
1896 	info.si_signo = sig;
1897 	info.si_errno = 0;
1898 	info.si_code  = code;
1899 	info.si_addr  = addr;
1900 	info.si_trapno = trapno;
1901 	return force_sig_info(&info);
1902 }
1903 
1904 /* For the rare architectures that include trap information using
1905  * si_trapno.
1906  */
send_sig_fault_trapno(int sig,int code,void __user * addr,int trapno,struct task_struct * t)1907 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1908 			  struct task_struct *t)
1909 {
1910 	struct kernel_siginfo info;
1911 
1912 	clear_siginfo(&info);
1913 	info.si_signo = sig;
1914 	info.si_errno = 0;
1915 	info.si_code  = code;
1916 	info.si_addr  = addr;
1917 	info.si_trapno = trapno;
1918 	return send_sig_info(info.si_signo, &info, t);
1919 }
1920 
kill_pgrp(struct pid * pid,int sig,int priv)1921 int kill_pgrp(struct pid *pid, int sig, int priv)
1922 {
1923 	int ret;
1924 
1925 	read_lock(&tasklist_lock);
1926 	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1927 	read_unlock(&tasklist_lock);
1928 
1929 	return ret;
1930 }
1931 EXPORT_SYMBOL(kill_pgrp);
1932 
kill_pid(struct pid * pid,int sig,int priv)1933 int kill_pid(struct pid *pid, int sig, int priv)
1934 {
1935 	return kill_pid_info(sig, __si_special(priv), pid);
1936 }
1937 EXPORT_SYMBOL(kill_pid);
1938 
1939 /*
1940  * These functions support sending signals using preallocated sigqueue
1941  * structures.  This is needed "because realtime applications cannot
1942  * afford to lose notifications of asynchronous events, like timer
1943  * expirations or I/O completions".  In the case of POSIX Timers
1944  * we allocate the sigqueue structure from the timer_create.  If this
1945  * allocation fails we are able to report the failure to the application
1946  * with an EAGAIN error.
1947  */
sigqueue_alloc(void)1948 struct sigqueue *sigqueue_alloc(void)
1949 {
1950 	return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1951 }
1952 
sigqueue_free(struct sigqueue * q)1953 void sigqueue_free(struct sigqueue *q)
1954 {
1955 	unsigned long flags;
1956 	spinlock_t *lock = &current->sighand->siglock;
1957 
1958 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1959 	/*
1960 	 * We must hold ->siglock while testing q->list
1961 	 * to serialize with collect_signal() or with
1962 	 * __exit_signal()->flush_sigqueue().
1963 	 */
1964 	spin_lock_irqsave(lock, flags);
1965 	q->flags &= ~SIGQUEUE_PREALLOC;
1966 	/*
1967 	 * If it is queued it will be freed when dequeued,
1968 	 * like the "regular" sigqueue.
1969 	 */
1970 	if (!list_empty(&q->list))
1971 		q = NULL;
1972 	spin_unlock_irqrestore(lock, flags);
1973 
1974 	if (q)
1975 		__sigqueue_free(q);
1976 }
1977 
send_sigqueue(struct sigqueue * q,struct pid * pid,enum pid_type type)1978 int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1979 {
1980 	int sig = q->info.si_signo;
1981 	struct sigpending *pending;
1982 	struct task_struct *t;
1983 	unsigned long flags;
1984 	int ret, result;
1985 
1986 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1987 
1988 	ret = -1;
1989 	rcu_read_lock();
1990 
1991 	/*
1992 	 * This function is used by POSIX timers to deliver a timer signal.
1993 	 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1994 	 * set), the signal must be delivered to the specific thread (queues
1995 	 * into t->pending).
1996 	 *
1997 	 * Where type is not PIDTYPE_PID, signals must be delivered to the
1998 	 * process. In this case, prefer to deliver to current if it is in
1999 	 * the same thread group as the target process, which avoids
2000 	 * unnecessarily waking up a potentially idle task.
2001 	 */
2002 	t = pid_task(pid, type);
2003 	if (!t)
2004 		goto ret;
2005 	if (type != PIDTYPE_PID && same_thread_group(t, current))
2006 		t = current;
2007 	if (!likely(lock_task_sighand(t, &flags)))
2008 		goto ret;
2009 
2010 	ret = 1; /* the signal is ignored */
2011 	result = TRACE_SIGNAL_IGNORED;
2012 	if (!prepare_signal(sig, t, false))
2013 		goto out;
2014 
2015 	ret = 0;
2016 	if (unlikely(!list_empty(&q->list))) {
2017 		/*
2018 		 * If an SI_TIMER entry is already queue just increment
2019 		 * the overrun count.
2020 		 */
2021 		BUG_ON(q->info.si_code != SI_TIMER);
2022 		q->info.si_overrun++;
2023 		result = TRACE_SIGNAL_ALREADY_PENDING;
2024 		goto out;
2025 	}
2026 	q->info.si_overrun = 0;
2027 
2028 	signalfd_notify(t, sig);
2029 	pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
2030 	list_add_tail(&q->list, &pending->list);
2031 	sigaddset(&pending->signal, sig);
2032 	complete_signal(sig, t, type);
2033 	result = TRACE_SIGNAL_DELIVERED;
2034 out:
2035 	trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
2036 	unlock_task_sighand(t, &flags);
2037 ret:
2038 	rcu_read_unlock();
2039 	return ret;
2040 }
2041 
do_notify_pidfd(struct task_struct * task)2042 static void do_notify_pidfd(struct task_struct *task)
2043 {
2044 	struct pid *pid;
2045 
2046 	WARN_ON(task->exit_state == 0);
2047 	pid = task_pid(task);
2048 	wake_up_all(&pid->wait_pidfd);
2049 }
2050 
2051 /*
2052  * Let a parent know about the death of a child.
2053  * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2054  *
2055  * Returns true if our parent ignored us and so we've switched to
2056  * self-reaping.
2057  */
do_notify_parent(struct task_struct * tsk,int sig)2058 bool do_notify_parent(struct task_struct *tsk, int sig)
2059 {
2060 	struct kernel_siginfo info;
2061 	unsigned long flags;
2062 	struct sighand_struct *psig;
2063 	bool autoreap = false;
2064 	u64 utime, stime;
2065 
2066 	WARN_ON_ONCE(sig == -1);
2067 
2068 	/* do_notify_parent_cldstop should have been called instead.  */
2069 	WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2070 
2071 	WARN_ON_ONCE(!tsk->ptrace &&
2072 	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2073 
2074 	/* Wake up all pidfd waiters */
2075 	do_notify_pidfd(tsk);
2076 
2077 	if (sig != SIGCHLD) {
2078 		/*
2079 		 * This is only possible if parent == real_parent.
2080 		 * Check if it has changed security domain.
2081 		 */
2082 		if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2083 			sig = SIGCHLD;
2084 	}
2085 
2086 	clear_siginfo(&info);
2087 	info.si_signo = sig;
2088 	info.si_errno = 0;
2089 	/*
2090 	 * We are under tasklist_lock here so our parent is tied to
2091 	 * us and cannot change.
2092 	 *
2093 	 * task_active_pid_ns will always return the same pid namespace
2094 	 * until a task passes through release_task.
2095 	 *
2096 	 * write_lock() currently calls preempt_disable() which is the
2097 	 * same as rcu_read_lock(), but according to Oleg, this is not
2098 	 * correct to rely on this
2099 	 */
2100 	rcu_read_lock();
2101 	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2102 	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2103 				       task_uid(tsk));
2104 	rcu_read_unlock();
2105 
2106 	task_cputime(tsk, &utime, &stime);
2107 	info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2108 	info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2109 
2110 	info.si_status = tsk->exit_code & 0x7f;
2111 	if (tsk->exit_code & 0x80)
2112 		info.si_code = CLD_DUMPED;
2113 	else if (tsk->exit_code & 0x7f)
2114 		info.si_code = CLD_KILLED;
2115 	else {
2116 		info.si_code = CLD_EXITED;
2117 		info.si_status = tsk->exit_code >> 8;
2118 	}
2119 
2120 	psig = tsk->parent->sighand;
2121 	spin_lock_irqsave(&psig->siglock, flags);
2122 	if (!tsk->ptrace && sig == SIGCHLD &&
2123 	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2124 	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2125 		/*
2126 		 * We are exiting and our parent doesn't care.  POSIX.1
2127 		 * defines special semantics for setting SIGCHLD to SIG_IGN
2128 		 * or setting the SA_NOCLDWAIT flag: we should be reaped
2129 		 * automatically and not left for our parent's wait4 call.
2130 		 * Rather than having the parent do it as a magic kind of
2131 		 * signal handler, we just set this to tell do_exit that we
2132 		 * can be cleaned up without becoming a zombie.  Note that
2133 		 * we still call __wake_up_parent in this case, because a
2134 		 * blocked sys_wait4 might now return -ECHILD.
2135 		 *
2136 		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2137 		 * is implementation-defined: we do (if you don't want
2138 		 * it, just use SIG_IGN instead).
2139 		 */
2140 		autoreap = true;
2141 		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2142 			sig = 0;
2143 	}
2144 	/*
2145 	 * Send with __send_signal as si_pid and si_uid are in the
2146 	 * parent's namespaces.
2147 	 */
2148 	if (valid_signal(sig) && sig)
2149 		__send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2150 	__wake_up_parent(tsk, tsk->parent);
2151 	spin_unlock_irqrestore(&psig->siglock, flags);
2152 
2153 	return autoreap;
2154 }
2155 
2156 /**
2157  * do_notify_parent_cldstop - notify parent of stopped/continued state change
2158  * @tsk: task reporting the state change
2159  * @for_ptracer: the notification is for ptracer
2160  * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2161  *
2162  * Notify @tsk's parent that the stopped/continued state has changed.  If
2163  * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2164  * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2165  *
2166  * CONTEXT:
2167  * Must be called with tasklist_lock at least read locked.
2168  */
do_notify_parent_cldstop(struct task_struct * tsk,bool for_ptracer,int why)2169 static void do_notify_parent_cldstop(struct task_struct *tsk,
2170 				     bool for_ptracer, int why)
2171 {
2172 	struct kernel_siginfo info;
2173 	unsigned long flags;
2174 	struct task_struct *parent;
2175 	struct sighand_struct *sighand;
2176 	u64 utime, stime;
2177 
2178 	if (for_ptracer) {
2179 		parent = tsk->parent;
2180 	} else {
2181 		tsk = tsk->group_leader;
2182 		parent = tsk->real_parent;
2183 	}
2184 
2185 	clear_siginfo(&info);
2186 	info.si_signo = SIGCHLD;
2187 	info.si_errno = 0;
2188 	/*
2189 	 * see comment in do_notify_parent() about the following 4 lines
2190 	 */
2191 	rcu_read_lock();
2192 	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2193 	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2194 	rcu_read_unlock();
2195 
2196 	task_cputime(tsk, &utime, &stime);
2197 	info.si_utime = nsec_to_clock_t(utime);
2198 	info.si_stime = nsec_to_clock_t(stime);
2199 
2200  	info.si_code = why;
2201  	switch (why) {
2202  	case CLD_CONTINUED:
2203  		info.si_status = SIGCONT;
2204  		break;
2205  	case CLD_STOPPED:
2206  		info.si_status = tsk->signal->group_exit_code & 0x7f;
2207  		break;
2208  	case CLD_TRAPPED:
2209  		info.si_status = tsk->exit_code & 0x7f;
2210  		break;
2211  	default:
2212  		BUG();
2213  	}
2214 
2215 	sighand = parent->sighand;
2216 	spin_lock_irqsave(&sighand->siglock, flags);
2217 	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2218 	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2219 		send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID);
2220 	/*
2221 	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2222 	 */
2223 	__wake_up_parent(tsk, parent);
2224 	spin_unlock_irqrestore(&sighand->siglock, flags);
2225 }
2226 
2227 /*
2228  * This must be called with current->sighand->siglock held.
2229  *
2230  * This should be the path for all ptrace stops.
2231  * We always set current->last_siginfo while stopped here.
2232  * That makes it a way to test a stopped process for
2233  * being ptrace-stopped vs being job-control-stopped.
2234  *
2235  * Returns the signal the ptracer requested the code resume
2236  * with.  If the code did not stop because the tracer is gone,
2237  * the stop signal remains unchanged unless clear_code.
2238  */
ptrace_stop(int exit_code,int why,unsigned long message,kernel_siginfo_t * info)2239 static int ptrace_stop(int exit_code, int why, unsigned long message,
2240 		       kernel_siginfo_t *info)
2241 	__releases(&current->sighand->siglock)
2242 	__acquires(&current->sighand->siglock)
2243 {
2244 	bool gstop_done = false;
2245 
2246 	if (arch_ptrace_stop_needed()) {
2247 		/*
2248 		 * The arch code has something special to do before a
2249 		 * ptrace stop.  This is allowed to block, e.g. for faults
2250 		 * on user stack pages.  We can't keep the siglock while
2251 		 * calling arch_ptrace_stop, so we must release it now.
2252 		 * To preserve proper semantics, we must do this before
2253 		 * any signal bookkeeping like checking group_stop_count.
2254 		 */
2255 		spin_unlock_irq(&current->sighand->siglock);
2256 		arch_ptrace_stop();
2257 		spin_lock_irq(&current->sighand->siglock);
2258 	}
2259 
2260 	/*
2261 	 * After this point ptrace_signal_wake_up or signal_wake_up
2262 	 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
2263 	 * signal comes in.  Handle previous ptrace_unlinks and fatal
2264 	 * signals here to prevent ptrace_stop sleeping in schedule.
2265 	 */
2266 	if (!current->ptrace || __fatal_signal_pending(current))
2267 		return exit_code;
2268 
2269 	set_special_state(TASK_TRACED);
2270 	current->jobctl |= JOBCTL_TRACED;
2271 
2272 	/*
2273 	 * We're committing to trapping.  TRACED should be visible before
2274 	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2275 	 * Also, transition to TRACED and updates to ->jobctl should be
2276 	 * atomic with respect to siglock and should be done after the arch
2277 	 * hook as siglock is released and regrabbed across it.
2278 	 *
2279 	 *     TRACER				    TRACEE
2280 	 *
2281 	 *     ptrace_attach()
2282 	 * [L]   wait_on_bit(JOBCTL_TRAPPING)	[S] set_special_state(TRACED)
2283 	 *     do_wait()
2284 	 *       set_current_state()                smp_wmb();
2285 	 *       ptrace_do_wait()
2286 	 *         wait_task_stopped()
2287 	 *           task_stopped_code()
2288 	 * [L]         task_is_traced()		[S] task_clear_jobctl_trapping();
2289 	 */
2290 	smp_wmb();
2291 
2292 	current->ptrace_message = message;
2293 	current->last_siginfo = info;
2294 	current->exit_code = exit_code;
2295 
2296 	/*
2297 	 * If @why is CLD_STOPPED, we're trapping to participate in a group
2298 	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
2299 	 * across siglock relocks since INTERRUPT was scheduled, PENDING
2300 	 * could be clear now.  We act as if SIGCONT is received after
2301 	 * TASK_TRACED is entered - ignore it.
2302 	 */
2303 	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2304 		gstop_done = task_participate_group_stop(current);
2305 
2306 	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2307 	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2308 	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2309 		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2310 
2311 	/* entering a trap, clear TRAPPING */
2312 	task_clear_jobctl_trapping(current);
2313 
2314 	spin_unlock_irq(&current->sighand->siglock);
2315 	read_lock(&tasklist_lock);
2316 	/*
2317 	 * Notify parents of the stop.
2318 	 *
2319 	 * While ptraced, there are two parents - the ptracer and
2320 	 * the real_parent of the group_leader.  The ptracer should
2321 	 * know about every stop while the real parent is only
2322 	 * interested in the completion of group stop.  The states
2323 	 * for the two don't interact with each other.  Notify
2324 	 * separately unless they're gonna be duplicates.
2325 	 */
2326 	if (current->ptrace)
2327 		do_notify_parent_cldstop(current, true, why);
2328 	if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2329 		do_notify_parent_cldstop(current, false, why);
2330 
2331 	/*
2332 	 * Don't want to allow preemption here, because
2333 	 * sys_ptrace() needs this task to be inactive.
2334 	 *
2335 	 * XXX: implement read_unlock_no_resched().
2336 	 */
2337 	preempt_disable();
2338 	read_unlock(&tasklist_lock);
2339 	cgroup_enter_frozen();
2340 	preempt_enable_no_resched();
2341 	schedule();
2342 	cgroup_leave_frozen(true);
2343 
2344 	/*
2345 	 * We are back.  Now reacquire the siglock before touching
2346 	 * last_siginfo, so that we are sure to have synchronized with
2347 	 * any signal-sending on another CPU that wants to examine it.
2348 	 */
2349 	spin_lock_irq(&current->sighand->siglock);
2350 	exit_code = current->exit_code;
2351 	current->last_siginfo = NULL;
2352 	current->ptrace_message = 0;
2353 	current->exit_code = 0;
2354 
2355 	/* LISTENING can be set only during STOP traps, clear it */
2356 	current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2357 
2358 	/*
2359 	 * Queued signals ignored us while we were stopped for tracing.
2360 	 * So check for any that we should take before resuming user mode.
2361 	 * This sets TIF_SIGPENDING, but never clears it.
2362 	 */
2363 	recalc_sigpending_tsk(current);
2364 	return exit_code;
2365 }
2366 
ptrace_do_notify(int signr,int exit_code,int why,unsigned long message)2367 static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2368 {
2369 	kernel_siginfo_t info;
2370 
2371 	clear_siginfo(&info);
2372 	info.si_signo = signr;
2373 	info.si_code = exit_code;
2374 	info.si_pid = task_pid_vnr(current);
2375 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2376 
2377 	/* Let the debugger run.  */
2378 	return ptrace_stop(exit_code, why, message, &info);
2379 }
2380 
ptrace_notify(int exit_code,unsigned long message)2381 int ptrace_notify(int exit_code, unsigned long message)
2382 {
2383 	int signr;
2384 
2385 	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2386 	if (unlikely(task_work_pending(current)))
2387 		task_work_run();
2388 
2389 	spin_lock_irq(&current->sighand->siglock);
2390 	signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2391 	spin_unlock_irq(&current->sighand->siglock);
2392 	return signr;
2393 }
2394 
2395 /**
2396  * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2397  * @signr: signr causing group stop if initiating
2398  *
2399  * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2400  * and participate in it.  If already set, participate in the existing
2401  * group stop.  If participated in a group stop (and thus slept), %true is
2402  * returned with siglock released.
2403  *
2404  * If ptraced, this function doesn't handle stop itself.  Instead,
2405  * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2406  * untouched.  The caller must ensure that INTERRUPT trap handling takes
2407  * places afterwards.
2408  *
2409  * CONTEXT:
2410  * Must be called with @current->sighand->siglock held, which is released
2411  * on %true return.
2412  *
2413  * RETURNS:
2414  * %false if group stop is already cancelled or ptrace trap is scheduled.
2415  * %true if participated in group stop.
2416  */
do_signal_stop(int signr)2417 static bool do_signal_stop(int signr)
2418 	__releases(&current->sighand->siglock)
2419 {
2420 	struct signal_struct *sig = current->signal;
2421 
2422 	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2423 		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2424 		struct task_struct *t;
2425 
2426 		/* signr will be recorded in task->jobctl for retries */
2427 		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2428 
2429 		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2430 		    unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2431 		    unlikely(sig->group_exec_task))
2432 			return false;
2433 		/*
2434 		 * There is no group stop already in progress.  We must
2435 		 * initiate one now.
2436 		 *
2437 		 * While ptraced, a task may be resumed while group stop is
2438 		 * still in effect and then receive a stop signal and
2439 		 * initiate another group stop.  This deviates from the
2440 		 * usual behavior as two consecutive stop signals can't
2441 		 * cause two group stops when !ptraced.  That is why we
2442 		 * also check !task_is_stopped(t) below.
2443 		 *
2444 		 * The condition can be distinguished by testing whether
2445 		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
2446 		 * group_exit_code in such case.
2447 		 *
2448 		 * This is not necessary for SIGNAL_STOP_CONTINUED because
2449 		 * an intervening stop signal is required to cause two
2450 		 * continued events regardless of ptrace.
2451 		 */
2452 		if (!(sig->flags & SIGNAL_STOP_STOPPED))
2453 			sig->group_exit_code = signr;
2454 
2455 		sig->group_stop_count = 0;
2456 
2457 		if (task_set_jobctl_pending(current, signr | gstop))
2458 			sig->group_stop_count++;
2459 
2460 		t = current;
2461 		while_each_thread(current, t) {
2462 			/*
2463 			 * Setting state to TASK_STOPPED for a group
2464 			 * stop is always done with the siglock held,
2465 			 * so this check has no races.
2466 			 */
2467 			if (!task_is_stopped(t) &&
2468 			    task_set_jobctl_pending(t, signr | gstop)) {
2469 				sig->group_stop_count++;
2470 				if (likely(!(t->ptrace & PT_SEIZED)))
2471 					signal_wake_up(t, 0);
2472 				else
2473 					ptrace_trap_notify(t);
2474 			}
2475 		}
2476 	}
2477 
2478 	if (likely(!current->ptrace)) {
2479 		int notify = 0;
2480 
2481 		/*
2482 		 * If there are no other threads in the group, or if there
2483 		 * is a group stop in progress and we are the last to stop,
2484 		 * report to the parent.
2485 		 */
2486 		if (task_participate_group_stop(current))
2487 			notify = CLD_STOPPED;
2488 
2489 		current->jobctl |= JOBCTL_STOPPED;
2490 		set_special_state(TASK_STOPPED);
2491 		spin_unlock_irq(&current->sighand->siglock);
2492 
2493 		/*
2494 		 * Notify the parent of the group stop completion.  Because
2495 		 * we're not holding either the siglock or tasklist_lock
2496 		 * here, ptracer may attach inbetween; however, this is for
2497 		 * group stop and should always be delivered to the real
2498 		 * parent of the group leader.  The new ptracer will get
2499 		 * its notification when this task transitions into
2500 		 * TASK_TRACED.
2501 		 */
2502 		if (notify) {
2503 			read_lock(&tasklist_lock);
2504 			do_notify_parent_cldstop(current, false, notify);
2505 			read_unlock(&tasklist_lock);
2506 		}
2507 
2508 		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2509 		cgroup_enter_frozen();
2510 		schedule();
2511 		return true;
2512 	} else {
2513 		/*
2514 		 * While ptraced, group stop is handled by STOP trap.
2515 		 * Schedule it and let the caller deal with it.
2516 		 */
2517 		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2518 		return false;
2519 	}
2520 }
2521 
2522 /**
2523  * do_jobctl_trap - take care of ptrace jobctl traps
2524  *
2525  * When PT_SEIZED, it's used for both group stop and explicit
2526  * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
2527  * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
2528  * the stop signal; otherwise, %SIGTRAP.
2529  *
2530  * When !PT_SEIZED, it's used only for group stop trap with stop signal
2531  * number as exit_code and no siginfo.
2532  *
2533  * CONTEXT:
2534  * Must be called with @current->sighand->siglock held, which may be
2535  * released and re-acquired before returning with intervening sleep.
2536  */
do_jobctl_trap(void)2537 static void do_jobctl_trap(void)
2538 {
2539 	struct signal_struct *signal = current->signal;
2540 	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2541 
2542 	if (current->ptrace & PT_SEIZED) {
2543 		if (!signal->group_stop_count &&
2544 		    !(signal->flags & SIGNAL_STOP_STOPPED))
2545 			signr = SIGTRAP;
2546 		WARN_ON_ONCE(!signr);
2547 		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2548 				 CLD_STOPPED, 0);
2549 	} else {
2550 		WARN_ON_ONCE(!signr);
2551 		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2552 	}
2553 }
2554 
2555 /**
2556  * do_freezer_trap - handle the freezer jobctl trap
2557  *
2558  * Puts the task into frozen state, if only the task is not about to quit.
2559  * In this case it drops JOBCTL_TRAP_FREEZE.
2560  *
2561  * CONTEXT:
2562  * Must be called with @current->sighand->siglock held,
2563  * which is always released before returning.
2564  */
do_freezer_trap(void)2565 static void do_freezer_trap(void)
2566 	__releases(&current->sighand->siglock)
2567 {
2568 	/*
2569 	 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2570 	 * let's make another loop to give it a chance to be handled.
2571 	 * In any case, we'll return back.
2572 	 */
2573 	if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2574 	     JOBCTL_TRAP_FREEZE) {
2575 		spin_unlock_irq(&current->sighand->siglock);
2576 		return;
2577 	}
2578 
2579 	/*
2580 	 * Now we're sure that there is no pending fatal signal and no
2581 	 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2582 	 * immediately (if there is a non-fatal signal pending), and
2583 	 * put the task into sleep.
2584 	 */
2585 	__set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2586 	clear_thread_flag(TIF_SIGPENDING);
2587 	spin_unlock_irq(&current->sighand->siglock);
2588 	cgroup_enter_frozen();
2589 	schedule();
2590 }
2591 
ptrace_signal(int signr,kernel_siginfo_t * info,enum pid_type type)2592 static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2593 {
2594 	/*
2595 	 * We do not check sig_kernel_stop(signr) but set this marker
2596 	 * unconditionally because we do not know whether debugger will
2597 	 * change signr. This flag has no meaning unless we are going
2598 	 * to stop after return from ptrace_stop(). In this case it will
2599 	 * be checked in do_signal_stop(), we should only stop if it was
2600 	 * not cleared by SIGCONT while we were sleeping. See also the
2601 	 * comment in dequeue_signal().
2602 	 */
2603 	current->jobctl |= JOBCTL_STOP_DEQUEUED;
2604 	signr = ptrace_stop(signr, CLD_TRAPPED, 0, info);
2605 
2606 	/* We're back.  Did the debugger cancel the sig?  */
2607 	if (signr == 0)
2608 		return signr;
2609 
2610 	/*
2611 	 * Update the siginfo structure if the signal has
2612 	 * changed.  If the debugger wanted something
2613 	 * specific in the siginfo structure then it should
2614 	 * have updated *info via PTRACE_SETSIGINFO.
2615 	 */
2616 	if (signr != info->si_signo) {
2617 		clear_siginfo(info);
2618 		info->si_signo = signr;
2619 		info->si_errno = 0;
2620 		info->si_code = SI_USER;
2621 		rcu_read_lock();
2622 		info->si_pid = task_pid_vnr(current->parent);
2623 		info->si_uid = from_kuid_munged(current_user_ns(),
2624 						task_uid(current->parent));
2625 		rcu_read_unlock();
2626 	}
2627 
2628 	/* If the (new) signal is now blocked, requeue it.  */
2629 	if (sigismember(&current->blocked, signr) ||
2630 	    fatal_signal_pending(current)) {
2631 		send_signal_locked(signr, info, current, type);
2632 		signr = 0;
2633 	}
2634 
2635 	return signr;
2636 }
2637 
hide_si_addr_tag_bits(struct ksignal * ksig)2638 static void hide_si_addr_tag_bits(struct ksignal *ksig)
2639 {
2640 	switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2641 	case SIL_FAULT:
2642 	case SIL_FAULT_TRAPNO:
2643 	case SIL_FAULT_MCEERR:
2644 	case SIL_FAULT_BNDERR:
2645 	case SIL_FAULT_PKUERR:
2646 	case SIL_FAULT_PERF_EVENT:
2647 		ksig->info.si_addr = arch_untagged_si_addr(
2648 			ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2649 		break;
2650 	case SIL_KILL:
2651 	case SIL_TIMER:
2652 	case SIL_POLL:
2653 	case SIL_CHLD:
2654 	case SIL_RT:
2655 	case SIL_SYS:
2656 		break;
2657 	}
2658 }
2659 
get_signal(struct ksignal * ksig)2660 bool get_signal(struct ksignal *ksig)
2661 {
2662 	struct sighand_struct *sighand = current->sighand;
2663 	struct signal_struct *signal = current->signal;
2664 	int signr;
2665 
2666 	clear_notify_signal();
2667 	if (unlikely(task_work_pending(current)))
2668 		task_work_run();
2669 
2670 	if (!task_sigpending(current))
2671 		return false;
2672 
2673 	if (unlikely(uprobe_deny_signal()))
2674 		return false;
2675 
2676 	/*
2677 	 * Do this once, we can't return to user-mode if freezing() == T.
2678 	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2679 	 * thus do not need another check after return.
2680 	 */
2681 	try_to_freeze();
2682 
2683 relock:
2684 	spin_lock_irq(&sighand->siglock);
2685 
2686 	/*
2687 	 * Every stopped thread goes here after wakeup. Check to see if
2688 	 * we should notify the parent, prepare_signal(SIGCONT) encodes
2689 	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2690 	 */
2691 	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2692 		int why;
2693 
2694 		if (signal->flags & SIGNAL_CLD_CONTINUED)
2695 			why = CLD_CONTINUED;
2696 		else
2697 			why = CLD_STOPPED;
2698 
2699 		signal->flags &= ~SIGNAL_CLD_MASK;
2700 
2701 		spin_unlock_irq(&sighand->siglock);
2702 
2703 		/*
2704 		 * Notify the parent that we're continuing.  This event is
2705 		 * always per-process and doesn't make whole lot of sense
2706 		 * for ptracers, who shouldn't consume the state via
2707 		 * wait(2) either, but, for backward compatibility, notify
2708 		 * the ptracer of the group leader too unless it's gonna be
2709 		 * a duplicate.
2710 		 */
2711 		read_lock(&tasklist_lock);
2712 		do_notify_parent_cldstop(current, false, why);
2713 
2714 		if (ptrace_reparented(current->group_leader))
2715 			do_notify_parent_cldstop(current->group_leader,
2716 						true, why);
2717 		read_unlock(&tasklist_lock);
2718 
2719 		goto relock;
2720 	}
2721 
2722 	for (;;) {
2723 		struct k_sigaction *ka;
2724 		enum pid_type type;
2725 
2726 		/* Has this task already been marked for death? */
2727 		if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2728 		     signal->group_exec_task) {
2729 			clear_siginfo(&ksig->info);
2730 			ksig->info.si_signo = signr = SIGKILL;
2731 			sigdelset(&current->pending.signal, SIGKILL);
2732 			trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2733 				&sighand->action[SIGKILL - 1]);
2734 			recalc_sigpending();
2735 			goto fatal;
2736 		}
2737 
2738 		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2739 		    do_signal_stop(0))
2740 			goto relock;
2741 
2742 		if (unlikely(current->jobctl &
2743 			     (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2744 			if (current->jobctl & JOBCTL_TRAP_MASK) {
2745 				do_jobctl_trap();
2746 				spin_unlock_irq(&sighand->siglock);
2747 			} else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2748 				do_freezer_trap();
2749 
2750 			goto relock;
2751 		}
2752 
2753 		/*
2754 		 * If the task is leaving the frozen state, let's update
2755 		 * cgroup counters and reset the frozen bit.
2756 		 */
2757 		if (unlikely(cgroup_task_frozen(current))) {
2758 			spin_unlock_irq(&sighand->siglock);
2759 			cgroup_leave_frozen(false);
2760 			goto relock;
2761 		}
2762 
2763 		/*
2764 		 * Signals generated by the execution of an instruction
2765 		 * need to be delivered before any other pending signals
2766 		 * so that the instruction pointer in the signal stack
2767 		 * frame points to the faulting instruction.
2768 		 */
2769 		type = PIDTYPE_PID;
2770 		signr = dequeue_synchronous_signal(&ksig->info);
2771 		if (!signr)
2772 			signr = dequeue_signal(current, &current->blocked,
2773 					       &ksig->info, &type);
2774 
2775 		if (!signr)
2776 			break; /* will return 0 */
2777 
2778 		if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2779 		    !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2780 			signr = ptrace_signal(signr, &ksig->info, type);
2781 			if (!signr)
2782 				continue;
2783 		}
2784 
2785 		ka = &sighand->action[signr-1];
2786 
2787 		/* Trace actually delivered signals. */
2788 		trace_signal_deliver(signr, &ksig->info, ka);
2789 
2790 		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
2791 			continue;
2792 		if (ka->sa.sa_handler != SIG_DFL) {
2793 			/* Run the handler.  */
2794 			ksig->ka = *ka;
2795 
2796 			if (ka->sa.sa_flags & SA_ONESHOT)
2797 				ka->sa.sa_handler = SIG_DFL;
2798 
2799 			break; /* will return non-zero "signr" value */
2800 		}
2801 
2802 		/*
2803 		 * Now we are doing the default action for this signal.
2804 		 */
2805 		if (sig_kernel_ignore(signr)) /* Default is nothing. */
2806 			continue;
2807 
2808 		/*
2809 		 * Global init gets no signals it doesn't want.
2810 		 * Container-init gets no signals it doesn't want from same
2811 		 * container.
2812 		 *
2813 		 * Note that if global/container-init sees a sig_kernel_only()
2814 		 * signal here, the signal must have been generated internally
2815 		 * or must have come from an ancestor namespace. In either
2816 		 * case, the signal cannot be dropped.
2817 		 */
2818 		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2819 				!sig_kernel_only(signr))
2820 			continue;
2821 
2822 		if (sig_kernel_stop(signr)) {
2823 			/*
2824 			 * The default action is to stop all threads in
2825 			 * the thread group.  The job control signals
2826 			 * do nothing in an orphaned pgrp, but SIGSTOP
2827 			 * always works.  Note that siglock needs to be
2828 			 * dropped during the call to is_orphaned_pgrp()
2829 			 * because of lock ordering with tasklist_lock.
2830 			 * This allows an intervening SIGCONT to be posted.
2831 			 * We need to check for that and bail out if necessary.
2832 			 */
2833 			if (signr != SIGSTOP) {
2834 				spin_unlock_irq(&sighand->siglock);
2835 
2836 				/* signals can be posted during this window */
2837 
2838 				if (is_current_pgrp_orphaned())
2839 					goto relock;
2840 
2841 				spin_lock_irq(&sighand->siglock);
2842 			}
2843 
2844 			if (likely(do_signal_stop(ksig->info.si_signo))) {
2845 				/* It released the siglock.  */
2846 				goto relock;
2847 			}
2848 
2849 			/*
2850 			 * We didn't actually stop, due to a race
2851 			 * with SIGCONT or something like that.
2852 			 */
2853 			continue;
2854 		}
2855 
2856 	fatal:
2857 		spin_unlock_irq(&sighand->siglock);
2858 		if (unlikely(cgroup_task_frozen(current)))
2859 			cgroup_leave_frozen(true);
2860 
2861 		/*
2862 		 * Anything else is fatal, maybe with a core dump.
2863 		 */
2864 		current->flags |= PF_SIGNALED;
2865 
2866 		if (sig_kernel_coredump(signr)) {
2867 			if (print_fatal_signals)
2868 				print_fatal_signal(ksig->info.si_signo);
2869 			proc_coredump_connector(current);
2870 			/*
2871 			 * If it was able to dump core, this kills all
2872 			 * other threads in the group and synchronizes with
2873 			 * their demise.  If we lost the race with another
2874 			 * thread getting here, it set group_exit_code
2875 			 * first and our do_group_exit call below will use
2876 			 * that value and ignore the one we pass it.
2877 			 */
2878 			do_coredump(&ksig->info);
2879 		}
2880 
2881 		/*
2882 		 * PF_USER_WORKER threads will catch and exit on fatal signals
2883 		 * themselves. They have cleanup that must be performed, so
2884 		 * we cannot call do_exit() on their behalf.
2885 		 */
2886 		if (current->flags & PF_USER_WORKER)
2887 			goto out;
2888 
2889 		/*
2890 		 * Death signals, no core dump.
2891 		 */
2892 		do_group_exit(ksig->info.si_signo);
2893 		/* NOTREACHED */
2894 	}
2895 	spin_unlock_irq(&sighand->siglock);
2896 out:
2897 	ksig->sig = signr;
2898 
2899 	if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2900 		hide_si_addr_tag_bits(ksig);
2901 
2902 	return ksig->sig > 0;
2903 }
2904 
2905 /**
2906  * signal_delivered - called after signal delivery to update blocked signals
2907  * @ksig:		kernel signal struct
2908  * @stepping:		nonzero if debugger single-step or block-step in use
2909  *
2910  * This function should be called when a signal has successfully been
2911  * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2912  * is always blocked), and the signal itself is blocked unless %SA_NODEFER
2913  * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2914  */
signal_delivered(struct ksignal * ksig,int stepping)2915 static void signal_delivered(struct ksignal *ksig, int stepping)
2916 {
2917 	sigset_t blocked;
2918 
2919 	/* A signal was successfully delivered, and the
2920 	   saved sigmask was stored on the signal frame,
2921 	   and will be restored by sigreturn.  So we can
2922 	   simply clear the restore sigmask flag.  */
2923 	clear_restore_sigmask();
2924 
2925 	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
2926 	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2927 		sigaddset(&blocked, ksig->sig);
2928 	set_current_blocked(&blocked);
2929 	if (current->sas_ss_flags & SS_AUTODISARM)
2930 		sas_ss_reset(current);
2931 	if (stepping)
2932 		ptrace_notify(SIGTRAP, 0);
2933 }
2934 
signal_setup_done(int failed,struct ksignal * ksig,int stepping)2935 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2936 {
2937 	if (failed)
2938 		force_sigsegv(ksig->sig);
2939 	else
2940 		signal_delivered(ksig, stepping);
2941 }
2942 
2943 /*
2944  * It could be that complete_signal() picked us to notify about the
2945  * group-wide signal. Other threads should be notified now to take
2946  * the shared signals in @which since we will not.
2947  */
retarget_shared_pending(struct task_struct * tsk,sigset_t * which)2948 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2949 {
2950 	sigset_t retarget;
2951 	struct task_struct *t;
2952 
2953 	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2954 	if (sigisemptyset(&retarget))
2955 		return;
2956 
2957 	t = tsk;
2958 	while_each_thread(tsk, t) {
2959 		if (t->flags & PF_EXITING)
2960 			continue;
2961 
2962 		if (!has_pending_signals(&retarget, &t->blocked))
2963 			continue;
2964 		/* Remove the signals this thread can handle. */
2965 		sigandsets(&retarget, &retarget, &t->blocked);
2966 
2967 		if (!task_sigpending(t))
2968 			signal_wake_up(t, 0);
2969 
2970 		if (sigisemptyset(&retarget))
2971 			break;
2972 	}
2973 }
2974 
exit_signals(struct task_struct * tsk)2975 void exit_signals(struct task_struct *tsk)
2976 {
2977 	int group_stop = 0;
2978 	sigset_t unblocked;
2979 
2980 	/*
2981 	 * @tsk is about to have PF_EXITING set - lock out users which
2982 	 * expect stable threadgroup.
2983 	 */
2984 	cgroup_threadgroup_change_begin(tsk);
2985 
2986 	if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
2987 		sched_mm_cid_exit_signals(tsk);
2988 		tsk->flags |= PF_EXITING;
2989 		cgroup_threadgroup_change_end(tsk);
2990 		return;
2991 	}
2992 
2993 	spin_lock_irq(&tsk->sighand->siglock);
2994 	/*
2995 	 * From now this task is not visible for group-wide signals,
2996 	 * see wants_signal(), do_signal_stop().
2997 	 */
2998 	sched_mm_cid_exit_signals(tsk);
2999 	tsk->flags |= PF_EXITING;
3000 
3001 	cgroup_threadgroup_change_end(tsk);
3002 
3003 	if (!task_sigpending(tsk))
3004 		goto out;
3005 
3006 	unblocked = tsk->blocked;
3007 	signotset(&unblocked);
3008 	retarget_shared_pending(tsk, &unblocked);
3009 
3010 	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3011 	    task_participate_group_stop(tsk))
3012 		group_stop = CLD_STOPPED;
3013 out:
3014 	spin_unlock_irq(&tsk->sighand->siglock);
3015 
3016 	/*
3017 	 * If group stop has completed, deliver the notification.  This
3018 	 * should always go to the real parent of the group leader.
3019 	 */
3020 	if (unlikely(group_stop)) {
3021 		read_lock(&tasklist_lock);
3022 		do_notify_parent_cldstop(tsk, false, group_stop);
3023 		read_unlock(&tasklist_lock);
3024 	}
3025 }
3026 
3027 /*
3028  * System call entry points.
3029  */
3030 
3031 /**
3032  *  sys_restart_syscall - restart a system call
3033  */
SYSCALL_DEFINE0(restart_syscall)3034 SYSCALL_DEFINE0(restart_syscall)
3035 {
3036 	struct restart_block *restart = &current->restart_block;
3037 	return restart->fn(restart);
3038 }
3039 
do_no_restart_syscall(struct restart_block * param)3040 long do_no_restart_syscall(struct restart_block *param)
3041 {
3042 	return -EINTR;
3043 }
3044 
__set_task_blocked(struct task_struct * tsk,const sigset_t * newset)3045 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3046 {
3047 	if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
3048 		sigset_t newblocked;
3049 		/* A set of now blocked but previously unblocked signals. */
3050 		sigandnsets(&newblocked, newset, &current->blocked);
3051 		retarget_shared_pending(tsk, &newblocked);
3052 	}
3053 	tsk->blocked = *newset;
3054 	recalc_sigpending();
3055 }
3056 
3057 /**
3058  * set_current_blocked - change current->blocked mask
3059  * @newset: new mask
3060  *
3061  * It is wrong to change ->blocked directly, this helper should be used
3062  * to ensure the process can't miss a shared signal we are going to block.
3063  */
set_current_blocked(sigset_t * newset)3064 void set_current_blocked(sigset_t *newset)
3065 {
3066 	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3067 	__set_current_blocked(newset);
3068 }
3069 
__set_current_blocked(const sigset_t * newset)3070 void __set_current_blocked(const sigset_t *newset)
3071 {
3072 	struct task_struct *tsk = current;
3073 
3074 	/*
3075 	 * In case the signal mask hasn't changed, there is nothing we need
3076 	 * to do. The current->blocked shouldn't be modified by other task.
3077 	 */
3078 	if (sigequalsets(&tsk->blocked, newset))
3079 		return;
3080 
3081 	spin_lock_irq(&tsk->sighand->siglock);
3082 	__set_task_blocked(tsk, newset);
3083 	spin_unlock_irq(&tsk->sighand->siglock);
3084 }
3085 
3086 /*
3087  * This is also useful for kernel threads that want to temporarily
3088  * (or permanently) block certain signals.
3089  *
3090  * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3091  * interface happily blocks "unblockable" signals like SIGKILL
3092  * and friends.
3093  */
sigprocmask(int how,sigset_t * set,sigset_t * oldset)3094 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3095 {
3096 	struct task_struct *tsk = current;
3097 	sigset_t newset;
3098 
3099 	/* Lockless, only current can change ->blocked, never from irq */
3100 	if (oldset)
3101 		*oldset = tsk->blocked;
3102 
3103 	switch (how) {
3104 	case SIG_BLOCK:
3105 		sigorsets(&newset, &tsk->blocked, set);
3106 		break;
3107 	case SIG_UNBLOCK:
3108 		sigandnsets(&newset, &tsk->blocked, set);
3109 		break;
3110 	case SIG_SETMASK:
3111 		newset = *set;
3112 		break;
3113 	default:
3114 		return -EINVAL;
3115 	}
3116 
3117 	__set_current_blocked(&newset);
3118 	return 0;
3119 }
3120 EXPORT_SYMBOL(sigprocmask);
3121 
3122 /*
3123  * The api helps set app-provided sigmasks.
3124  *
3125  * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3126  * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3127  *
3128  * Note that it does set_restore_sigmask() in advance, so it must be always
3129  * paired with restore_saved_sigmask_unless() before return from syscall.
3130  */
set_user_sigmask(const sigset_t __user * umask,size_t sigsetsize)3131 int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3132 {
3133 	sigset_t kmask;
3134 
3135 	if (!umask)
3136 		return 0;
3137 	if (sigsetsize != sizeof(sigset_t))
3138 		return -EINVAL;
3139 	if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3140 		return -EFAULT;
3141 
3142 	set_restore_sigmask();
3143 	current->saved_sigmask = current->blocked;
3144 	set_current_blocked(&kmask);
3145 
3146 	return 0;
3147 }
3148 
3149 #ifdef CONFIG_COMPAT
set_compat_user_sigmask(const compat_sigset_t __user * umask,size_t sigsetsize)3150 int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3151 			    size_t sigsetsize)
3152 {
3153 	sigset_t kmask;
3154 
3155 	if (!umask)
3156 		return 0;
3157 	if (sigsetsize != sizeof(compat_sigset_t))
3158 		return -EINVAL;
3159 	if (get_compat_sigset(&kmask, umask))
3160 		return -EFAULT;
3161 
3162 	set_restore_sigmask();
3163 	current->saved_sigmask = current->blocked;
3164 	set_current_blocked(&kmask);
3165 
3166 	return 0;
3167 }
3168 #endif
3169 
3170 /**
3171  *  sys_rt_sigprocmask - change the list of currently blocked signals
3172  *  @how: whether to add, remove, or set signals
3173  *  @nset: stores pending signals
3174  *  @oset: previous value of signal mask if non-null
3175  *  @sigsetsize: size of sigset_t type
3176  */
SYSCALL_DEFINE4(rt_sigprocmask,int,how,sigset_t __user *,nset,sigset_t __user *,oset,size_t,sigsetsize)3177 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3178 		sigset_t __user *, oset, size_t, sigsetsize)
3179 {
3180 	sigset_t old_set, new_set;
3181 	int error;
3182 
3183 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3184 	if (sigsetsize != sizeof(sigset_t))
3185 		return -EINVAL;
3186 
3187 	old_set = current->blocked;
3188 
3189 	if (nset) {
3190 		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3191 			return -EFAULT;
3192 		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3193 
3194 		error = sigprocmask(how, &new_set, NULL);
3195 		if (error)
3196 			return error;
3197 	}
3198 
3199 	if (oset) {
3200 		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3201 			return -EFAULT;
3202 	}
3203 
3204 	return 0;
3205 }
3206 
3207 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigprocmask,int,how,compat_sigset_t __user *,nset,compat_sigset_t __user *,oset,compat_size_t,sigsetsize)3208 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3209 		compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3210 {
3211 	sigset_t old_set = current->blocked;
3212 
3213 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3214 	if (sigsetsize != sizeof(sigset_t))
3215 		return -EINVAL;
3216 
3217 	if (nset) {
3218 		sigset_t new_set;
3219 		int error;
3220 		if (get_compat_sigset(&new_set, nset))
3221 			return -EFAULT;
3222 		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3223 
3224 		error = sigprocmask(how, &new_set, NULL);
3225 		if (error)
3226 			return error;
3227 	}
3228 	return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3229 }
3230 #endif
3231 
do_sigpending(sigset_t * set)3232 static void do_sigpending(sigset_t *set)
3233 {
3234 	spin_lock_irq(&current->sighand->siglock);
3235 	sigorsets(set, &current->pending.signal,
3236 		  &current->signal->shared_pending.signal);
3237 	spin_unlock_irq(&current->sighand->siglock);
3238 
3239 	/* Outside the lock because only this thread touches it.  */
3240 	sigandsets(set, &current->blocked, set);
3241 }
3242 
3243 /**
3244  *  sys_rt_sigpending - examine a pending signal that has been raised
3245  *			while blocked
3246  *  @uset: stores pending signals
3247  *  @sigsetsize: size of sigset_t type or larger
3248  */
SYSCALL_DEFINE2(rt_sigpending,sigset_t __user *,uset,size_t,sigsetsize)3249 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3250 {
3251 	sigset_t set;
3252 
3253 	if (sigsetsize > sizeof(*uset))
3254 		return -EINVAL;
3255 
3256 	do_sigpending(&set);
3257 
3258 	if (copy_to_user(uset, &set, sigsetsize))
3259 		return -EFAULT;
3260 
3261 	return 0;
3262 }
3263 
3264 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(rt_sigpending,compat_sigset_t __user *,uset,compat_size_t,sigsetsize)3265 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3266 		compat_size_t, sigsetsize)
3267 {
3268 	sigset_t set;
3269 
3270 	if (sigsetsize > sizeof(*uset))
3271 		return -EINVAL;
3272 
3273 	do_sigpending(&set);
3274 
3275 	return put_compat_sigset(uset, &set, sigsetsize);
3276 }
3277 #endif
3278 
3279 static const struct {
3280 	unsigned char limit, layout;
3281 } sig_sicodes[] = {
3282 	[SIGILL]  = { NSIGILL,  SIL_FAULT },
3283 	[SIGFPE]  = { NSIGFPE,  SIL_FAULT },
3284 	[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3285 	[SIGBUS]  = { NSIGBUS,  SIL_FAULT },
3286 	[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3287 #if defined(SIGEMT)
3288 	[SIGEMT]  = { NSIGEMT,  SIL_FAULT },
3289 #endif
3290 	[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3291 	[SIGPOLL] = { NSIGPOLL, SIL_POLL },
3292 	[SIGSYS]  = { NSIGSYS,  SIL_SYS },
3293 };
3294 
known_siginfo_layout(unsigned sig,int si_code)3295 static bool known_siginfo_layout(unsigned sig, int si_code)
3296 {
3297 	if (si_code == SI_KERNEL)
3298 		return true;
3299 	else if ((si_code > SI_USER)) {
3300 		if (sig_specific_sicodes(sig)) {
3301 			if (si_code <= sig_sicodes[sig].limit)
3302 				return true;
3303 		}
3304 		else if (si_code <= NSIGPOLL)
3305 			return true;
3306 	}
3307 	else if (si_code >= SI_DETHREAD)
3308 		return true;
3309 	else if (si_code == SI_ASYNCNL)
3310 		return true;
3311 	return false;
3312 }
3313 
siginfo_layout(unsigned sig,int si_code)3314 enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3315 {
3316 	enum siginfo_layout layout = SIL_KILL;
3317 	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3318 		if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3319 		    (si_code <= sig_sicodes[sig].limit)) {
3320 			layout = sig_sicodes[sig].layout;
3321 			/* Handle the exceptions */
3322 			if ((sig == SIGBUS) &&
3323 			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3324 				layout = SIL_FAULT_MCEERR;
3325 			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3326 				layout = SIL_FAULT_BNDERR;
3327 #ifdef SEGV_PKUERR
3328 			else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3329 				layout = SIL_FAULT_PKUERR;
3330 #endif
3331 			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3332 				layout = SIL_FAULT_PERF_EVENT;
3333 			else if (IS_ENABLED(CONFIG_SPARC) &&
3334 				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3335 				layout = SIL_FAULT_TRAPNO;
3336 			else if (IS_ENABLED(CONFIG_ALPHA) &&
3337 				 ((sig == SIGFPE) ||
3338 				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3339 				layout = SIL_FAULT_TRAPNO;
3340 		}
3341 		else if (si_code <= NSIGPOLL)
3342 			layout = SIL_POLL;
3343 	} else {
3344 		if (si_code == SI_TIMER)
3345 			layout = SIL_TIMER;
3346 		else if (si_code == SI_SIGIO)
3347 			layout = SIL_POLL;
3348 		else if (si_code < 0)
3349 			layout = SIL_RT;
3350 	}
3351 	return layout;
3352 }
3353 
si_expansion(const siginfo_t __user * info)3354 static inline char __user *si_expansion(const siginfo_t __user *info)
3355 {
3356 	return ((char __user *)info) + sizeof(struct kernel_siginfo);
3357 }
3358 
copy_siginfo_to_user(siginfo_t __user * to,const kernel_siginfo_t * from)3359 int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3360 {
3361 	char __user *expansion = si_expansion(to);
3362 	if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3363 		return -EFAULT;
3364 	if (clear_user(expansion, SI_EXPANSION_SIZE))
3365 		return -EFAULT;
3366 	return 0;
3367 }
3368 
post_copy_siginfo_from_user(kernel_siginfo_t * info,const siginfo_t __user * from)3369 static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3370 				       const siginfo_t __user *from)
3371 {
3372 	if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3373 		char __user *expansion = si_expansion(from);
3374 		char buf[SI_EXPANSION_SIZE];
3375 		int i;
3376 		/*
3377 		 * An unknown si_code might need more than
3378 		 * sizeof(struct kernel_siginfo) bytes.  Verify all of the
3379 		 * extra bytes are 0.  This guarantees copy_siginfo_to_user
3380 		 * will return this data to userspace exactly.
3381 		 */
3382 		if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3383 			return -EFAULT;
3384 		for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3385 			if (buf[i] != 0)
3386 				return -E2BIG;
3387 		}
3388 	}
3389 	return 0;
3390 }
3391 
__copy_siginfo_from_user(int signo,kernel_siginfo_t * to,const siginfo_t __user * from)3392 static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3393 				    const siginfo_t __user *from)
3394 {
3395 	if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3396 		return -EFAULT;
3397 	to->si_signo = signo;
3398 	return post_copy_siginfo_from_user(to, from);
3399 }
3400 
copy_siginfo_from_user(kernel_siginfo_t * to,const siginfo_t __user * from)3401 int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3402 {
3403 	if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3404 		return -EFAULT;
3405 	return post_copy_siginfo_from_user(to, from);
3406 }
3407 
3408 #ifdef CONFIG_COMPAT
3409 /**
3410  * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3411  * @to: compat siginfo destination
3412  * @from: kernel siginfo source
3413  *
3414  * Note: This function does not work properly for the SIGCHLD on x32, but
3415  * fortunately it doesn't have to.  The only valid callers for this function are
3416  * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3417  * The latter does not care because SIGCHLD will never cause a coredump.
3418  */
copy_siginfo_to_external32(struct compat_siginfo * to,const struct kernel_siginfo * from)3419 void copy_siginfo_to_external32(struct compat_siginfo *to,
3420 		const struct kernel_siginfo *from)
3421 {
3422 	memset(to, 0, sizeof(*to));
3423 
3424 	to->si_signo = from->si_signo;
3425 	to->si_errno = from->si_errno;
3426 	to->si_code  = from->si_code;
3427 	switch(siginfo_layout(from->si_signo, from->si_code)) {
3428 	case SIL_KILL:
3429 		to->si_pid = from->si_pid;
3430 		to->si_uid = from->si_uid;
3431 		break;
3432 	case SIL_TIMER:
3433 		to->si_tid     = from->si_tid;
3434 		to->si_overrun = from->si_overrun;
3435 		to->si_int     = from->si_int;
3436 		break;
3437 	case SIL_POLL:
3438 		to->si_band = from->si_band;
3439 		to->si_fd   = from->si_fd;
3440 		break;
3441 	case SIL_FAULT:
3442 		to->si_addr = ptr_to_compat(from->si_addr);
3443 		break;
3444 	case SIL_FAULT_TRAPNO:
3445 		to->si_addr = ptr_to_compat(from->si_addr);
3446 		to->si_trapno = from->si_trapno;
3447 		break;
3448 	case SIL_FAULT_MCEERR:
3449 		to->si_addr = ptr_to_compat(from->si_addr);
3450 		to->si_addr_lsb = from->si_addr_lsb;
3451 		break;
3452 	case SIL_FAULT_BNDERR:
3453 		to->si_addr = ptr_to_compat(from->si_addr);
3454 		to->si_lower = ptr_to_compat(from->si_lower);
3455 		to->si_upper = ptr_to_compat(from->si_upper);
3456 		break;
3457 	case SIL_FAULT_PKUERR:
3458 		to->si_addr = ptr_to_compat(from->si_addr);
3459 		to->si_pkey = from->si_pkey;
3460 		break;
3461 	case SIL_FAULT_PERF_EVENT:
3462 		to->si_addr = ptr_to_compat(from->si_addr);
3463 		to->si_perf_data = from->si_perf_data;
3464 		to->si_perf_type = from->si_perf_type;
3465 		to->si_perf_flags = from->si_perf_flags;
3466 		break;
3467 	case SIL_CHLD:
3468 		to->si_pid = from->si_pid;
3469 		to->si_uid = from->si_uid;
3470 		to->si_status = from->si_status;
3471 		to->si_utime = from->si_utime;
3472 		to->si_stime = from->si_stime;
3473 		break;
3474 	case SIL_RT:
3475 		to->si_pid = from->si_pid;
3476 		to->si_uid = from->si_uid;
3477 		to->si_int = from->si_int;
3478 		break;
3479 	case SIL_SYS:
3480 		to->si_call_addr = ptr_to_compat(from->si_call_addr);
3481 		to->si_syscall   = from->si_syscall;
3482 		to->si_arch      = from->si_arch;
3483 		break;
3484 	}
3485 }
3486 
__copy_siginfo_to_user32(struct compat_siginfo __user * to,const struct kernel_siginfo * from)3487 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3488 			   const struct kernel_siginfo *from)
3489 {
3490 	struct compat_siginfo new;
3491 
3492 	copy_siginfo_to_external32(&new, from);
3493 	if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3494 		return -EFAULT;
3495 	return 0;
3496 }
3497 
post_copy_siginfo_from_user32(kernel_siginfo_t * to,const struct compat_siginfo * from)3498 static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3499 					 const struct compat_siginfo *from)
3500 {
3501 	clear_siginfo(to);
3502 	to->si_signo = from->si_signo;
3503 	to->si_errno = from->si_errno;
3504 	to->si_code  = from->si_code;
3505 	switch(siginfo_layout(from->si_signo, from->si_code)) {
3506 	case SIL_KILL:
3507 		to->si_pid = from->si_pid;
3508 		to->si_uid = from->si_uid;
3509 		break;
3510 	case SIL_TIMER:
3511 		to->si_tid     = from->si_tid;
3512 		to->si_overrun = from->si_overrun;
3513 		to->si_int     = from->si_int;
3514 		break;
3515 	case SIL_POLL:
3516 		to->si_band = from->si_band;
3517 		to->si_fd   = from->si_fd;
3518 		break;
3519 	case SIL_FAULT:
3520 		to->si_addr = compat_ptr(from->si_addr);
3521 		break;
3522 	case SIL_FAULT_TRAPNO:
3523 		to->si_addr = compat_ptr(from->si_addr);
3524 		to->si_trapno = from->si_trapno;
3525 		break;
3526 	case SIL_FAULT_MCEERR:
3527 		to->si_addr = compat_ptr(from->si_addr);
3528 		to->si_addr_lsb = from->si_addr_lsb;
3529 		break;
3530 	case SIL_FAULT_BNDERR:
3531 		to->si_addr = compat_ptr(from->si_addr);
3532 		to->si_lower = compat_ptr(from->si_lower);
3533 		to->si_upper = compat_ptr(from->si_upper);
3534 		break;
3535 	case SIL_FAULT_PKUERR:
3536 		to->si_addr = compat_ptr(from->si_addr);
3537 		to->si_pkey = from->si_pkey;
3538 		break;
3539 	case SIL_FAULT_PERF_EVENT:
3540 		to->si_addr = compat_ptr(from->si_addr);
3541 		to->si_perf_data = from->si_perf_data;
3542 		to->si_perf_type = from->si_perf_type;
3543 		to->si_perf_flags = from->si_perf_flags;
3544 		break;
3545 	case SIL_CHLD:
3546 		to->si_pid    = from->si_pid;
3547 		to->si_uid    = from->si_uid;
3548 		to->si_status = from->si_status;
3549 #ifdef CONFIG_X86_X32_ABI
3550 		if (in_x32_syscall()) {
3551 			to->si_utime = from->_sifields._sigchld_x32._utime;
3552 			to->si_stime = from->_sifields._sigchld_x32._stime;
3553 		} else
3554 #endif
3555 		{
3556 			to->si_utime = from->si_utime;
3557 			to->si_stime = from->si_stime;
3558 		}
3559 		break;
3560 	case SIL_RT:
3561 		to->si_pid = from->si_pid;
3562 		to->si_uid = from->si_uid;
3563 		to->si_int = from->si_int;
3564 		break;
3565 	case SIL_SYS:
3566 		to->si_call_addr = compat_ptr(from->si_call_addr);
3567 		to->si_syscall   = from->si_syscall;
3568 		to->si_arch      = from->si_arch;
3569 		break;
3570 	}
3571 	return 0;
3572 }
3573 
__copy_siginfo_from_user32(int signo,struct kernel_siginfo * to,const struct compat_siginfo __user * ufrom)3574 static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3575 				      const struct compat_siginfo __user *ufrom)
3576 {
3577 	struct compat_siginfo from;
3578 
3579 	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3580 		return -EFAULT;
3581 
3582 	from.si_signo = signo;
3583 	return post_copy_siginfo_from_user32(to, &from);
3584 }
3585 
copy_siginfo_from_user32(struct kernel_siginfo * to,const struct compat_siginfo __user * ufrom)3586 int copy_siginfo_from_user32(struct kernel_siginfo *to,
3587 			     const struct compat_siginfo __user *ufrom)
3588 {
3589 	struct compat_siginfo from;
3590 
3591 	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3592 		return -EFAULT;
3593 
3594 	return post_copy_siginfo_from_user32(to, &from);
3595 }
3596 #endif /* CONFIG_COMPAT */
3597 
3598 /**
3599  *  do_sigtimedwait - wait for queued signals specified in @which
3600  *  @which: queued signals to wait for
3601  *  @info: if non-null, the signal's siginfo is returned here
3602  *  @ts: upper bound on process time suspension
3603  */
do_sigtimedwait(const sigset_t * which,kernel_siginfo_t * info,const struct timespec64 * ts)3604 static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3605 		    const struct timespec64 *ts)
3606 {
3607 	ktime_t *to = NULL, timeout = KTIME_MAX;
3608 	struct task_struct *tsk = current;
3609 	sigset_t mask = *which;
3610 	enum pid_type type;
3611 	int sig, ret = 0;
3612 
3613 	if (ts) {
3614 		if (!timespec64_valid(ts))
3615 			return -EINVAL;
3616 		timeout = timespec64_to_ktime(*ts);
3617 		to = &timeout;
3618 	}
3619 
3620 	/*
3621 	 * Invert the set of allowed signals to get those we want to block.
3622 	 */
3623 	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3624 	signotset(&mask);
3625 
3626 	spin_lock_irq(&tsk->sighand->siglock);
3627 	sig = dequeue_signal(tsk, &mask, info, &type);
3628 	if (!sig && timeout) {
3629 		/*
3630 		 * None ready, temporarily unblock those we're interested
3631 		 * while we are sleeping in so that we'll be awakened when
3632 		 * they arrive. Unblocking is always fine, we can avoid
3633 		 * set_current_blocked().
3634 		 */
3635 		tsk->real_blocked = tsk->blocked;
3636 		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3637 		recalc_sigpending();
3638 		spin_unlock_irq(&tsk->sighand->siglock);
3639 
3640 		__set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3641 		ret = schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3642 					       HRTIMER_MODE_REL);
3643 		spin_lock_irq(&tsk->sighand->siglock);
3644 		__set_task_blocked(tsk, &tsk->real_blocked);
3645 		sigemptyset(&tsk->real_blocked);
3646 		sig = dequeue_signal(tsk, &mask, info, &type);
3647 	}
3648 	spin_unlock_irq(&tsk->sighand->siglock);
3649 
3650 	if (sig)
3651 		return sig;
3652 	return ret ? -EINTR : -EAGAIN;
3653 }
3654 
3655 /**
3656  *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
3657  *			in @uthese
3658  *  @uthese: queued signals to wait for
3659  *  @uinfo: if non-null, the signal's siginfo is returned here
3660  *  @uts: upper bound on process time suspension
3661  *  @sigsetsize: size of sigset_t type
3662  */
SYSCALL_DEFINE4(rt_sigtimedwait,const sigset_t __user *,uthese,siginfo_t __user *,uinfo,const struct __kernel_timespec __user *,uts,size_t,sigsetsize)3663 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3664 		siginfo_t __user *, uinfo,
3665 		const struct __kernel_timespec __user *, uts,
3666 		size_t, sigsetsize)
3667 {
3668 	sigset_t these;
3669 	struct timespec64 ts;
3670 	kernel_siginfo_t info;
3671 	int ret;
3672 
3673 	/* XXX: Don't preclude handling different sized sigset_t's.  */
3674 	if (sigsetsize != sizeof(sigset_t))
3675 		return -EINVAL;
3676 
3677 	if (copy_from_user(&these, uthese, sizeof(these)))
3678 		return -EFAULT;
3679 
3680 	if (uts) {
3681 		if (get_timespec64(&ts, uts))
3682 			return -EFAULT;
3683 	}
3684 
3685 	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3686 
3687 	if (ret > 0 && uinfo) {
3688 		if (copy_siginfo_to_user(uinfo, &info))
3689 			ret = -EFAULT;
3690 	}
3691 
3692 	return ret;
3693 }
3694 
3695 #ifdef CONFIG_COMPAT_32BIT_TIME
SYSCALL_DEFINE4(rt_sigtimedwait_time32,const sigset_t __user *,uthese,siginfo_t __user *,uinfo,const struct old_timespec32 __user *,uts,size_t,sigsetsize)3696 SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3697 		siginfo_t __user *, uinfo,
3698 		const struct old_timespec32 __user *, uts,
3699 		size_t, sigsetsize)
3700 {
3701 	sigset_t these;
3702 	struct timespec64 ts;
3703 	kernel_siginfo_t info;
3704 	int ret;
3705 
3706 	if (sigsetsize != sizeof(sigset_t))
3707 		return -EINVAL;
3708 
3709 	if (copy_from_user(&these, uthese, sizeof(these)))
3710 		return -EFAULT;
3711 
3712 	if (uts) {
3713 		if (get_old_timespec32(&ts, uts))
3714 			return -EFAULT;
3715 	}
3716 
3717 	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3718 
3719 	if (ret > 0 && uinfo) {
3720 		if (copy_siginfo_to_user(uinfo, &info))
3721 			ret = -EFAULT;
3722 	}
3723 
3724 	return ret;
3725 }
3726 #endif
3727 
3728 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64,compat_sigset_t __user *,uthese,struct compat_siginfo __user *,uinfo,struct __kernel_timespec __user *,uts,compat_size_t,sigsetsize)3729 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3730 		struct compat_siginfo __user *, uinfo,
3731 		struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3732 {
3733 	sigset_t s;
3734 	struct timespec64 t;
3735 	kernel_siginfo_t info;
3736 	long ret;
3737 
3738 	if (sigsetsize != sizeof(sigset_t))
3739 		return -EINVAL;
3740 
3741 	if (get_compat_sigset(&s, uthese))
3742 		return -EFAULT;
3743 
3744 	if (uts) {
3745 		if (get_timespec64(&t, uts))
3746 			return -EFAULT;
3747 	}
3748 
3749 	ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3750 
3751 	if (ret > 0 && uinfo) {
3752 		if (copy_siginfo_to_user32(uinfo, &info))
3753 			ret = -EFAULT;
3754 	}
3755 
3756 	return ret;
3757 }
3758 
3759 #ifdef CONFIG_COMPAT_32BIT_TIME
COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32,compat_sigset_t __user *,uthese,struct compat_siginfo __user *,uinfo,struct old_timespec32 __user *,uts,compat_size_t,sigsetsize)3760 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3761 		struct compat_siginfo __user *, uinfo,
3762 		struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3763 {
3764 	sigset_t s;
3765 	struct timespec64 t;
3766 	kernel_siginfo_t info;
3767 	long ret;
3768 
3769 	if (sigsetsize != sizeof(sigset_t))
3770 		return -EINVAL;
3771 
3772 	if (get_compat_sigset(&s, uthese))
3773 		return -EFAULT;
3774 
3775 	if (uts) {
3776 		if (get_old_timespec32(&t, uts))
3777 			return -EFAULT;
3778 	}
3779 
3780 	ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3781 
3782 	if (ret > 0 && uinfo) {
3783 		if (copy_siginfo_to_user32(uinfo, &info))
3784 			ret = -EFAULT;
3785 	}
3786 
3787 	return ret;
3788 }
3789 #endif
3790 #endif
3791 
prepare_kill_siginfo(int sig,struct kernel_siginfo * info)3792 static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3793 {
3794 	clear_siginfo(info);
3795 	info->si_signo = sig;
3796 	info->si_errno = 0;
3797 	info->si_code = SI_USER;
3798 	info->si_pid = task_tgid_vnr(current);
3799 	info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3800 }
3801 
3802 /**
3803  *  sys_kill - send a signal to a process
3804  *  @pid: the PID of the process
3805  *  @sig: signal to be sent
3806  */
SYSCALL_DEFINE2(kill,pid_t,pid,int,sig)3807 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3808 {
3809 	struct kernel_siginfo info;
3810 
3811 	prepare_kill_siginfo(sig, &info);
3812 
3813 	return kill_something_info(sig, &info, pid);
3814 }
3815 
3816 /*
3817  * Verify that the signaler and signalee either are in the same pid namespace
3818  * or that the signaler's pid namespace is an ancestor of the signalee's pid
3819  * namespace.
3820  */
access_pidfd_pidns(struct pid * pid)3821 static bool access_pidfd_pidns(struct pid *pid)
3822 {
3823 	struct pid_namespace *active = task_active_pid_ns(current);
3824 	struct pid_namespace *p = ns_of_pid(pid);
3825 
3826 	for (;;) {
3827 		if (!p)
3828 			return false;
3829 		if (p == active)
3830 			break;
3831 		p = p->parent;
3832 	}
3833 
3834 	return true;
3835 }
3836 
copy_siginfo_from_user_any(kernel_siginfo_t * kinfo,siginfo_t __user * info)3837 static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3838 		siginfo_t __user *info)
3839 {
3840 #ifdef CONFIG_COMPAT
3841 	/*
3842 	 * Avoid hooking up compat syscalls and instead handle necessary
3843 	 * conversions here. Note, this is a stop-gap measure and should not be
3844 	 * considered a generic solution.
3845 	 */
3846 	if (in_compat_syscall())
3847 		return copy_siginfo_from_user32(
3848 			kinfo, (struct compat_siginfo __user *)info);
3849 #endif
3850 	return copy_siginfo_from_user(kinfo, info);
3851 }
3852 
pidfd_to_pid(const struct file * file)3853 static struct pid *pidfd_to_pid(const struct file *file)
3854 {
3855 	struct pid *pid;
3856 
3857 	pid = pidfd_pid(file);
3858 	if (!IS_ERR(pid))
3859 		return pid;
3860 
3861 	return tgid_pidfd_to_pid(file);
3862 }
3863 
3864 /**
3865  * sys_pidfd_send_signal - Signal a process through a pidfd
3866  * @pidfd:  file descriptor of the process
3867  * @sig:    signal to send
3868  * @info:   signal info
3869  * @flags:  future flags
3870  *
3871  * The syscall currently only signals via PIDTYPE_PID which covers
3872  * kill(<positive-pid>, <signal>. It does not signal threads or process
3873  * groups.
3874  * In order to extend the syscall to threads and process groups the @flags
3875  * argument should be used. In essence, the @flags argument will determine
3876  * what is signaled and not the file descriptor itself. Put in other words,
3877  * grouping is a property of the flags argument not a property of the file
3878  * descriptor.
3879  *
3880  * Return: 0 on success, negative errno on failure
3881  */
SYSCALL_DEFINE4(pidfd_send_signal,int,pidfd,int,sig,siginfo_t __user *,info,unsigned int,flags)3882 SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3883 		siginfo_t __user *, info, unsigned int, flags)
3884 {
3885 	int ret;
3886 	struct fd f;
3887 	struct pid *pid;
3888 	kernel_siginfo_t kinfo;
3889 
3890 	/* Enforce flags be set to 0 until we add an extension. */
3891 	if (flags)
3892 		return -EINVAL;
3893 
3894 	f = fdget(pidfd);
3895 	if (!f.file)
3896 		return -EBADF;
3897 
3898 	/* Is this a pidfd? */
3899 	pid = pidfd_to_pid(f.file);
3900 	if (IS_ERR(pid)) {
3901 		ret = PTR_ERR(pid);
3902 		goto err;
3903 	}
3904 
3905 	ret = -EINVAL;
3906 	if (!access_pidfd_pidns(pid))
3907 		goto err;
3908 
3909 	if (info) {
3910 		ret = copy_siginfo_from_user_any(&kinfo, info);
3911 		if (unlikely(ret))
3912 			goto err;
3913 
3914 		ret = -EINVAL;
3915 		if (unlikely(sig != kinfo.si_signo))
3916 			goto err;
3917 
3918 		/* Only allow sending arbitrary signals to yourself. */
3919 		ret = -EPERM;
3920 		if ((task_pid(current) != pid) &&
3921 		    (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3922 			goto err;
3923 	} else {
3924 		prepare_kill_siginfo(sig, &kinfo);
3925 	}
3926 
3927 	ret = kill_pid_info(sig, &kinfo, pid);
3928 
3929 err:
3930 	fdput(f);
3931 	return ret;
3932 }
3933 
3934 static int
do_send_specific(pid_t tgid,pid_t pid,int sig,struct kernel_siginfo * info)3935 do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3936 {
3937 	struct task_struct *p;
3938 	int error = -ESRCH;
3939 
3940 	rcu_read_lock();
3941 	p = find_task_by_vpid(pid);
3942 	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3943 		error = check_kill_permission(sig, info, p);
3944 		/*
3945 		 * The null signal is a permissions and process existence
3946 		 * probe.  No signal is actually delivered.
3947 		 */
3948 		if (!error && sig) {
3949 			error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3950 			/*
3951 			 * If lock_task_sighand() failed we pretend the task
3952 			 * dies after receiving the signal. The window is tiny,
3953 			 * and the signal is private anyway.
3954 			 */
3955 			if (unlikely(error == -ESRCH))
3956 				error = 0;
3957 		}
3958 	}
3959 	rcu_read_unlock();
3960 
3961 	return error;
3962 }
3963 
do_tkill(pid_t tgid,pid_t pid,int sig)3964 static int do_tkill(pid_t tgid, pid_t pid, int sig)
3965 {
3966 	struct kernel_siginfo info;
3967 
3968 	clear_siginfo(&info);
3969 	info.si_signo = sig;
3970 	info.si_errno = 0;
3971 	info.si_code = SI_TKILL;
3972 	info.si_pid = task_tgid_vnr(current);
3973 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3974 
3975 	return do_send_specific(tgid, pid, sig, &info);
3976 }
3977 
3978 /**
3979  *  sys_tgkill - send signal to one specific thread
3980  *  @tgid: the thread group ID of the thread
3981  *  @pid: the PID of the thread
3982  *  @sig: signal to be sent
3983  *
3984  *  This syscall also checks the @tgid and returns -ESRCH even if the PID
3985  *  exists but it's not belonging to the target process anymore. This
3986  *  method solves the problem of threads exiting and PIDs getting reused.
3987  */
SYSCALL_DEFINE3(tgkill,pid_t,tgid,pid_t,pid,int,sig)3988 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3989 {
3990 	/* This is only valid for single tasks */
3991 	if (pid <= 0 || tgid <= 0)
3992 		return -EINVAL;
3993 
3994 	return do_tkill(tgid, pid, sig);
3995 }
3996 
3997 /**
3998  *  sys_tkill - send signal to one specific task
3999  *  @pid: the PID of the task
4000  *  @sig: signal to be sent
4001  *
4002  *  Send a signal to only one task, even if it's a CLONE_THREAD task.
4003  */
SYSCALL_DEFINE2(tkill,pid_t,pid,int,sig)4004 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4005 {
4006 	/* This is only valid for single tasks */
4007 	if (pid <= 0)
4008 		return -EINVAL;
4009 
4010 	return do_tkill(0, pid, sig);
4011 }
4012 
do_rt_sigqueueinfo(pid_t pid,int sig,kernel_siginfo_t * info)4013 static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4014 {
4015 	/* Not even root can pretend to send signals from the kernel.
4016 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4017 	 */
4018 	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4019 	    (task_pid_vnr(current) != pid))
4020 		return -EPERM;
4021 
4022 	/* POSIX.1b doesn't mention process groups.  */
4023 	return kill_proc_info(sig, info, pid);
4024 }
4025 
4026 /**
4027  *  sys_rt_sigqueueinfo - send signal information to a signal
4028  *  @pid: the PID of the thread
4029  *  @sig: signal to be sent
4030  *  @uinfo: signal info to be sent
4031  */
SYSCALL_DEFINE3(rt_sigqueueinfo,pid_t,pid,int,sig,siginfo_t __user *,uinfo)4032 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4033 		siginfo_t __user *, uinfo)
4034 {
4035 	kernel_siginfo_t info;
4036 	int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4037 	if (unlikely(ret))
4038 		return ret;
4039 	return do_rt_sigqueueinfo(pid, sig, &info);
4040 }
4041 
4042 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,compat_pid_t,pid,int,sig,struct compat_siginfo __user *,uinfo)4043 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4044 			compat_pid_t, pid,
4045 			int, sig,
4046 			struct compat_siginfo __user *, uinfo)
4047 {
4048 	kernel_siginfo_t info;
4049 	int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4050 	if (unlikely(ret))
4051 		return ret;
4052 	return do_rt_sigqueueinfo(pid, sig, &info);
4053 }
4054 #endif
4055 
do_rt_tgsigqueueinfo(pid_t tgid,pid_t pid,int sig,kernel_siginfo_t * info)4056 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4057 {
4058 	/* This is only valid for single tasks */
4059 	if (pid <= 0 || tgid <= 0)
4060 		return -EINVAL;
4061 
4062 	/* Not even root can pretend to send signals from the kernel.
4063 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4064 	 */
4065 	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4066 	    (task_pid_vnr(current) != pid))
4067 		return -EPERM;
4068 
4069 	return do_send_specific(tgid, pid, sig, info);
4070 }
4071 
SYSCALL_DEFINE4(rt_tgsigqueueinfo,pid_t,tgid,pid_t,pid,int,sig,siginfo_t __user *,uinfo)4072 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4073 		siginfo_t __user *, uinfo)
4074 {
4075 	kernel_siginfo_t info;
4076 	int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4077 	if (unlikely(ret))
4078 		return ret;
4079 	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4080 }
4081 
4082 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,compat_pid_t,tgid,compat_pid_t,pid,int,sig,struct compat_siginfo __user *,uinfo)4083 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4084 			compat_pid_t, tgid,
4085 			compat_pid_t, pid,
4086 			int, sig,
4087 			struct compat_siginfo __user *, uinfo)
4088 {
4089 	kernel_siginfo_t info;
4090 	int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4091 	if (unlikely(ret))
4092 		return ret;
4093 	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4094 }
4095 #endif
4096 
4097 /*
4098  * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4099  */
kernel_sigaction(int sig,__sighandler_t action)4100 void kernel_sigaction(int sig, __sighandler_t action)
4101 {
4102 	spin_lock_irq(&current->sighand->siglock);
4103 	current->sighand->action[sig - 1].sa.sa_handler = action;
4104 	if (action == SIG_IGN) {
4105 		sigset_t mask;
4106 
4107 		sigemptyset(&mask);
4108 		sigaddset(&mask, sig);
4109 
4110 		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
4111 		flush_sigqueue_mask(&mask, &current->pending);
4112 		recalc_sigpending();
4113 	}
4114 	spin_unlock_irq(&current->sighand->siglock);
4115 }
4116 EXPORT_SYMBOL(kernel_sigaction);
4117 
sigaction_compat_abi(struct k_sigaction * act,struct k_sigaction * oact)4118 void __weak sigaction_compat_abi(struct k_sigaction *act,
4119 		struct k_sigaction *oact)
4120 {
4121 }
4122 
do_sigaction(int sig,struct k_sigaction * act,struct k_sigaction * oact)4123 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4124 {
4125 	struct task_struct *p = current, *t;
4126 	struct k_sigaction *k;
4127 	sigset_t mask;
4128 
4129 	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4130 		return -EINVAL;
4131 
4132 	k = &p->sighand->action[sig-1];
4133 
4134 	spin_lock_irq(&p->sighand->siglock);
4135 	if (k->sa.sa_flags & SA_IMMUTABLE) {
4136 		spin_unlock_irq(&p->sighand->siglock);
4137 		return -EINVAL;
4138 	}
4139 	if (oact)
4140 		*oact = *k;
4141 
4142 	/*
4143 	 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4144 	 * e.g. by having an architecture use the bit in their uapi.
4145 	 */
4146 	BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4147 
4148 	/*
4149 	 * Clear unknown flag bits in order to allow userspace to detect missing
4150 	 * support for flag bits and to allow the kernel to use non-uapi bits
4151 	 * internally.
4152 	 */
4153 	if (act)
4154 		act->sa.sa_flags &= UAPI_SA_FLAGS;
4155 	if (oact)
4156 		oact->sa.sa_flags &= UAPI_SA_FLAGS;
4157 
4158 	sigaction_compat_abi(act, oact);
4159 
4160 	if (act) {
4161 		sigdelsetmask(&act->sa.sa_mask,
4162 			      sigmask(SIGKILL) | sigmask(SIGSTOP));
4163 		*k = *act;
4164 		/*
4165 		 * POSIX 3.3.1.3:
4166 		 *  "Setting a signal action to SIG_IGN for a signal that is
4167 		 *   pending shall cause the pending signal to be discarded,
4168 		 *   whether or not it is blocked."
4169 		 *
4170 		 *  "Setting a signal action to SIG_DFL for a signal that is
4171 		 *   pending and whose default action is to ignore the signal
4172 		 *   (for example, SIGCHLD), shall cause the pending signal to
4173 		 *   be discarded, whether or not it is blocked"
4174 		 */
4175 		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4176 			sigemptyset(&mask);
4177 			sigaddset(&mask, sig);
4178 			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4179 			for_each_thread(p, t)
4180 				flush_sigqueue_mask(&mask, &t->pending);
4181 		}
4182 	}
4183 
4184 	spin_unlock_irq(&p->sighand->siglock);
4185 	return 0;
4186 }
4187 
4188 #ifdef CONFIG_DYNAMIC_SIGFRAME
sigaltstack_lock(void)4189 static inline void sigaltstack_lock(void)
4190 	__acquires(&current->sighand->siglock)
4191 {
4192 	spin_lock_irq(&current->sighand->siglock);
4193 }
4194 
sigaltstack_unlock(void)4195 static inline void sigaltstack_unlock(void)
4196 	__releases(&current->sighand->siglock)
4197 {
4198 	spin_unlock_irq(&current->sighand->siglock);
4199 }
4200 #else
sigaltstack_lock(void)4201 static inline void sigaltstack_lock(void) { }
sigaltstack_unlock(void)4202 static inline void sigaltstack_unlock(void) { }
4203 #endif
4204 
4205 static int
do_sigaltstack(const stack_t * ss,stack_t * oss,unsigned long sp,size_t min_ss_size)4206 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4207 		size_t min_ss_size)
4208 {
4209 	struct task_struct *t = current;
4210 	int ret = 0;
4211 
4212 	if (oss) {
4213 		memset(oss, 0, sizeof(stack_t));
4214 		oss->ss_sp = (void __user *) t->sas_ss_sp;
4215 		oss->ss_size = t->sas_ss_size;
4216 		oss->ss_flags = sas_ss_flags(sp) |
4217 			(current->sas_ss_flags & SS_FLAG_BITS);
4218 	}
4219 
4220 	if (ss) {
4221 		void __user *ss_sp = ss->ss_sp;
4222 		size_t ss_size = ss->ss_size;
4223 		unsigned ss_flags = ss->ss_flags;
4224 		int ss_mode;
4225 
4226 		if (unlikely(on_sig_stack(sp)))
4227 			return -EPERM;
4228 
4229 		ss_mode = ss_flags & ~SS_FLAG_BITS;
4230 		if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4231 				ss_mode != 0))
4232 			return -EINVAL;
4233 
4234 		/*
4235 		 * Return before taking any locks if no actual
4236 		 * sigaltstack changes were requested.
4237 		 */
4238 		if (t->sas_ss_sp == (unsigned long)ss_sp &&
4239 		    t->sas_ss_size == ss_size &&
4240 		    t->sas_ss_flags == ss_flags)
4241 			return 0;
4242 
4243 		sigaltstack_lock();
4244 		if (ss_mode == SS_DISABLE) {
4245 			ss_size = 0;
4246 			ss_sp = NULL;
4247 		} else {
4248 			if (unlikely(ss_size < min_ss_size))
4249 				ret = -ENOMEM;
4250 			if (!sigaltstack_size_valid(ss_size))
4251 				ret = -ENOMEM;
4252 		}
4253 		if (!ret) {
4254 			t->sas_ss_sp = (unsigned long) ss_sp;
4255 			t->sas_ss_size = ss_size;
4256 			t->sas_ss_flags = ss_flags;
4257 		}
4258 		sigaltstack_unlock();
4259 	}
4260 	return ret;
4261 }
4262 
SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss,stack_t __user *,uoss)4263 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4264 {
4265 	stack_t new, old;
4266 	int err;
4267 	if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4268 		return -EFAULT;
4269 	err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4270 			      current_user_stack_pointer(),
4271 			      MINSIGSTKSZ);
4272 	if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4273 		err = -EFAULT;
4274 	return err;
4275 }
4276 
restore_altstack(const stack_t __user * uss)4277 int restore_altstack(const stack_t __user *uss)
4278 {
4279 	stack_t new;
4280 	if (copy_from_user(&new, uss, sizeof(stack_t)))
4281 		return -EFAULT;
4282 	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4283 			     MINSIGSTKSZ);
4284 	/* squash all but EFAULT for now */
4285 	return 0;
4286 }
4287 
__save_altstack(stack_t __user * uss,unsigned long sp)4288 int __save_altstack(stack_t __user *uss, unsigned long sp)
4289 {
4290 	struct task_struct *t = current;
4291 	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4292 		__put_user(t->sas_ss_flags, &uss->ss_flags) |
4293 		__put_user(t->sas_ss_size, &uss->ss_size);
4294 	return err;
4295 }
4296 
4297 #ifdef CONFIG_COMPAT
do_compat_sigaltstack(const compat_stack_t __user * uss_ptr,compat_stack_t __user * uoss_ptr)4298 static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4299 				 compat_stack_t __user *uoss_ptr)
4300 {
4301 	stack_t uss, uoss;
4302 	int ret;
4303 
4304 	if (uss_ptr) {
4305 		compat_stack_t uss32;
4306 		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4307 			return -EFAULT;
4308 		uss.ss_sp = compat_ptr(uss32.ss_sp);
4309 		uss.ss_flags = uss32.ss_flags;
4310 		uss.ss_size = uss32.ss_size;
4311 	}
4312 	ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4313 			     compat_user_stack_pointer(),
4314 			     COMPAT_MINSIGSTKSZ);
4315 	if (ret >= 0 && uoss_ptr)  {
4316 		compat_stack_t old;
4317 		memset(&old, 0, sizeof(old));
4318 		old.ss_sp = ptr_to_compat(uoss.ss_sp);
4319 		old.ss_flags = uoss.ss_flags;
4320 		old.ss_size = uoss.ss_size;
4321 		if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4322 			ret = -EFAULT;
4323 	}
4324 	return ret;
4325 }
4326 
COMPAT_SYSCALL_DEFINE2(sigaltstack,const compat_stack_t __user *,uss_ptr,compat_stack_t __user *,uoss_ptr)4327 COMPAT_SYSCALL_DEFINE2(sigaltstack,
4328 			const compat_stack_t __user *, uss_ptr,
4329 			compat_stack_t __user *, uoss_ptr)
4330 {
4331 	return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4332 }
4333 
compat_restore_altstack(const compat_stack_t __user * uss)4334 int compat_restore_altstack(const compat_stack_t __user *uss)
4335 {
4336 	int err = do_compat_sigaltstack(uss, NULL);
4337 	/* squash all but -EFAULT for now */
4338 	return err == -EFAULT ? err : 0;
4339 }
4340 
__compat_save_altstack(compat_stack_t __user * uss,unsigned long sp)4341 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4342 {
4343 	int err;
4344 	struct task_struct *t = current;
4345 	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4346 			 &uss->ss_sp) |
4347 		__put_user(t->sas_ss_flags, &uss->ss_flags) |
4348 		__put_user(t->sas_ss_size, &uss->ss_size);
4349 	return err;
4350 }
4351 #endif
4352 
4353 #ifdef __ARCH_WANT_SYS_SIGPENDING
4354 
4355 /**
4356  *  sys_sigpending - examine pending signals
4357  *  @uset: where mask of pending signal is returned
4358  */
SYSCALL_DEFINE1(sigpending,old_sigset_t __user *,uset)4359 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4360 {
4361 	sigset_t set;
4362 
4363 	if (sizeof(old_sigset_t) > sizeof(*uset))
4364 		return -EINVAL;
4365 
4366 	do_sigpending(&set);
4367 
4368 	if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4369 		return -EFAULT;
4370 
4371 	return 0;
4372 }
4373 
4374 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE1(sigpending,compat_old_sigset_t __user *,set32)4375 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4376 {
4377 	sigset_t set;
4378 
4379 	do_sigpending(&set);
4380 
4381 	return put_user(set.sig[0], set32);
4382 }
4383 #endif
4384 
4385 #endif
4386 
4387 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
4388 /**
4389  *  sys_sigprocmask - examine and change blocked signals
4390  *  @how: whether to add, remove, or set signals
4391  *  @nset: signals to add or remove (if non-null)
4392  *  @oset: previous value of signal mask if non-null
4393  *
4394  * Some platforms have their own version with special arguments;
4395  * others support only sys_rt_sigprocmask.
4396  */
4397 
SYSCALL_DEFINE3(sigprocmask,int,how,old_sigset_t __user *,nset,old_sigset_t __user *,oset)4398 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4399 		old_sigset_t __user *, oset)
4400 {
4401 	old_sigset_t old_set, new_set;
4402 	sigset_t new_blocked;
4403 
4404 	old_set = current->blocked.sig[0];
4405 
4406 	if (nset) {
4407 		if (copy_from_user(&new_set, nset, sizeof(*nset)))
4408 			return -EFAULT;
4409 
4410 		new_blocked = current->blocked;
4411 
4412 		switch (how) {
4413 		case SIG_BLOCK:
4414 			sigaddsetmask(&new_blocked, new_set);
4415 			break;
4416 		case SIG_UNBLOCK:
4417 			sigdelsetmask(&new_blocked, new_set);
4418 			break;
4419 		case SIG_SETMASK:
4420 			new_blocked.sig[0] = new_set;
4421 			break;
4422 		default:
4423 			return -EINVAL;
4424 		}
4425 
4426 		set_current_blocked(&new_blocked);
4427 	}
4428 
4429 	if (oset) {
4430 		if (copy_to_user(oset, &old_set, sizeof(*oset)))
4431 			return -EFAULT;
4432 	}
4433 
4434 	return 0;
4435 }
4436 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4437 
4438 #ifndef CONFIG_ODD_RT_SIGACTION
4439 /**
4440  *  sys_rt_sigaction - alter an action taken by a process
4441  *  @sig: signal to be sent
4442  *  @act: new sigaction
4443  *  @oact: used to save the previous sigaction
4444  *  @sigsetsize: size of sigset_t type
4445  */
SYSCALL_DEFINE4(rt_sigaction,int,sig,const struct sigaction __user *,act,struct sigaction __user *,oact,size_t,sigsetsize)4446 SYSCALL_DEFINE4(rt_sigaction, int, sig,
4447 		const struct sigaction __user *, act,
4448 		struct sigaction __user *, oact,
4449 		size_t, sigsetsize)
4450 {
4451 	struct k_sigaction new_sa, old_sa;
4452 	int ret;
4453 
4454 	/* XXX: Don't preclude handling different sized sigset_t's.  */
4455 	if (sigsetsize != sizeof(sigset_t))
4456 		return -EINVAL;
4457 
4458 	if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4459 		return -EFAULT;
4460 
4461 	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4462 	if (ret)
4463 		return ret;
4464 
4465 	if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4466 		return -EFAULT;
4467 
4468 	return 0;
4469 }
4470 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigaction,int,sig,const struct compat_sigaction __user *,act,struct compat_sigaction __user *,oact,compat_size_t,sigsetsize)4471 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4472 		const struct compat_sigaction __user *, act,
4473 		struct compat_sigaction __user *, oact,
4474 		compat_size_t, sigsetsize)
4475 {
4476 	struct k_sigaction new_ka, old_ka;
4477 #ifdef __ARCH_HAS_SA_RESTORER
4478 	compat_uptr_t restorer;
4479 #endif
4480 	int ret;
4481 
4482 	/* XXX: Don't preclude handling different sized sigset_t's.  */
4483 	if (sigsetsize != sizeof(compat_sigset_t))
4484 		return -EINVAL;
4485 
4486 	if (act) {
4487 		compat_uptr_t handler;
4488 		ret = get_user(handler, &act->sa_handler);
4489 		new_ka.sa.sa_handler = compat_ptr(handler);
4490 #ifdef __ARCH_HAS_SA_RESTORER
4491 		ret |= get_user(restorer, &act->sa_restorer);
4492 		new_ka.sa.sa_restorer = compat_ptr(restorer);
4493 #endif
4494 		ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4495 		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4496 		if (ret)
4497 			return -EFAULT;
4498 	}
4499 
4500 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4501 	if (!ret && oact) {
4502 		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4503 			       &oact->sa_handler);
4504 		ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4505 					 sizeof(oact->sa_mask));
4506 		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4507 #ifdef __ARCH_HAS_SA_RESTORER
4508 		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4509 				&oact->sa_restorer);
4510 #endif
4511 	}
4512 	return ret;
4513 }
4514 #endif
4515 #endif /* !CONFIG_ODD_RT_SIGACTION */
4516 
4517 #ifdef CONFIG_OLD_SIGACTION
SYSCALL_DEFINE3(sigaction,int,sig,const struct old_sigaction __user *,act,struct old_sigaction __user *,oact)4518 SYSCALL_DEFINE3(sigaction, int, sig,
4519 		const struct old_sigaction __user *, act,
4520 	        struct old_sigaction __user *, oact)
4521 {
4522 	struct k_sigaction new_ka, old_ka;
4523 	int ret;
4524 
4525 	if (act) {
4526 		old_sigset_t mask;
4527 		if (!access_ok(act, sizeof(*act)) ||
4528 		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4529 		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4530 		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4531 		    __get_user(mask, &act->sa_mask))
4532 			return -EFAULT;
4533 #ifdef __ARCH_HAS_KA_RESTORER
4534 		new_ka.ka_restorer = NULL;
4535 #endif
4536 		siginitset(&new_ka.sa.sa_mask, mask);
4537 	}
4538 
4539 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4540 
4541 	if (!ret && oact) {
4542 		if (!access_ok(oact, sizeof(*oact)) ||
4543 		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4544 		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4545 		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4546 		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4547 			return -EFAULT;
4548 	}
4549 
4550 	return ret;
4551 }
4552 #endif
4553 #ifdef CONFIG_COMPAT_OLD_SIGACTION
COMPAT_SYSCALL_DEFINE3(sigaction,int,sig,const struct compat_old_sigaction __user *,act,struct compat_old_sigaction __user *,oact)4554 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4555 		const struct compat_old_sigaction __user *, act,
4556 	        struct compat_old_sigaction __user *, oact)
4557 {
4558 	struct k_sigaction new_ka, old_ka;
4559 	int ret;
4560 	compat_old_sigset_t mask;
4561 	compat_uptr_t handler, restorer;
4562 
4563 	if (act) {
4564 		if (!access_ok(act, sizeof(*act)) ||
4565 		    __get_user(handler, &act->sa_handler) ||
4566 		    __get_user(restorer, &act->sa_restorer) ||
4567 		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4568 		    __get_user(mask, &act->sa_mask))
4569 			return -EFAULT;
4570 
4571 #ifdef __ARCH_HAS_KA_RESTORER
4572 		new_ka.ka_restorer = NULL;
4573 #endif
4574 		new_ka.sa.sa_handler = compat_ptr(handler);
4575 		new_ka.sa.sa_restorer = compat_ptr(restorer);
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(ptr_to_compat(old_ka.sa.sa_handler),
4584 			       &oact->sa_handler) ||
4585 		    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4586 			       &oact->sa_restorer) ||
4587 		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4588 		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4589 			return -EFAULT;
4590 	}
4591 	return ret;
4592 }
4593 #endif
4594 
4595 #ifdef CONFIG_SGETMASK_SYSCALL
4596 
4597 /*
4598  * For backwards compatibility.  Functionality superseded by sigprocmask.
4599  */
SYSCALL_DEFINE0(sgetmask)4600 SYSCALL_DEFINE0(sgetmask)
4601 {
4602 	/* SMP safe */
4603 	return current->blocked.sig[0];
4604 }
4605 
SYSCALL_DEFINE1(ssetmask,int,newmask)4606 SYSCALL_DEFINE1(ssetmask, int, newmask)
4607 {
4608 	int old = current->blocked.sig[0];
4609 	sigset_t newset;
4610 
4611 	siginitset(&newset, newmask);
4612 	set_current_blocked(&newset);
4613 
4614 	return old;
4615 }
4616 #endif /* CONFIG_SGETMASK_SYSCALL */
4617 
4618 #ifdef __ARCH_WANT_SYS_SIGNAL
4619 /*
4620  * For backwards compatibility.  Functionality superseded by sigaction.
4621  */
SYSCALL_DEFINE2(signal,int,sig,__sighandler_t,handler)4622 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4623 {
4624 	struct k_sigaction new_sa, old_sa;
4625 	int ret;
4626 
4627 	new_sa.sa.sa_handler = handler;
4628 	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4629 	sigemptyset(&new_sa.sa.sa_mask);
4630 
4631 	ret = do_sigaction(sig, &new_sa, &old_sa);
4632 
4633 	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4634 }
4635 #endif /* __ARCH_WANT_SYS_SIGNAL */
4636 
4637 #ifdef __ARCH_WANT_SYS_PAUSE
4638 
SYSCALL_DEFINE0(pause)4639 SYSCALL_DEFINE0(pause)
4640 {
4641 	while (!signal_pending(current)) {
4642 		__set_current_state(TASK_INTERRUPTIBLE);
4643 		schedule();
4644 	}
4645 	return -ERESTARTNOHAND;
4646 }
4647 
4648 #endif
4649 
sigsuspend(sigset_t * set)4650 static int sigsuspend(sigset_t *set)
4651 {
4652 	current->saved_sigmask = current->blocked;
4653 	set_current_blocked(set);
4654 
4655 	while (!signal_pending(current)) {
4656 		__set_current_state(TASK_INTERRUPTIBLE);
4657 		schedule();
4658 	}
4659 	set_restore_sigmask();
4660 	return -ERESTARTNOHAND;
4661 }
4662 
4663 /**
4664  *  sys_rt_sigsuspend - replace the signal mask for a value with the
4665  *	@unewset value until a signal is received
4666  *  @unewset: new signal mask value
4667  *  @sigsetsize: size of sigset_t type
4668  */
SYSCALL_DEFINE2(rt_sigsuspend,sigset_t __user *,unewset,size_t,sigsetsize)4669 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4670 {
4671 	sigset_t newset;
4672 
4673 	/* XXX: Don't preclude handling different sized sigset_t's.  */
4674 	if (sigsetsize != sizeof(sigset_t))
4675 		return -EINVAL;
4676 
4677 	if (copy_from_user(&newset, unewset, sizeof(newset)))
4678 		return -EFAULT;
4679 	return sigsuspend(&newset);
4680 }
4681 
4682 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(rt_sigsuspend,compat_sigset_t __user *,unewset,compat_size_t,sigsetsize)4683 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4684 {
4685 	sigset_t newset;
4686 
4687 	/* XXX: Don't preclude handling different sized sigset_t's.  */
4688 	if (sigsetsize != sizeof(sigset_t))
4689 		return -EINVAL;
4690 
4691 	if (get_compat_sigset(&newset, unewset))
4692 		return -EFAULT;
4693 	return sigsuspend(&newset);
4694 }
4695 #endif
4696 
4697 #ifdef CONFIG_OLD_SIGSUSPEND
SYSCALL_DEFINE1(sigsuspend,old_sigset_t,mask)4698 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4699 {
4700 	sigset_t blocked;
4701 	siginitset(&blocked, mask);
4702 	return sigsuspend(&blocked);
4703 }
4704 #endif
4705 #ifdef CONFIG_OLD_SIGSUSPEND3
SYSCALL_DEFINE3(sigsuspend,int,unused1,int,unused2,old_sigset_t,mask)4706 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4707 {
4708 	sigset_t blocked;
4709 	siginitset(&blocked, mask);
4710 	return sigsuspend(&blocked);
4711 }
4712 #endif
4713 
arch_vma_name(struct vm_area_struct * vma)4714 __weak const char *arch_vma_name(struct vm_area_struct *vma)
4715 {
4716 	return NULL;
4717 }
4718 
siginfo_buildtime_checks(void)4719 static inline void siginfo_buildtime_checks(void)
4720 {
4721 	BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4722 
4723 	/* Verify the offsets in the two siginfos match */
4724 #define CHECK_OFFSET(field) \
4725 	BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4726 
4727 	/* kill */
4728 	CHECK_OFFSET(si_pid);
4729 	CHECK_OFFSET(si_uid);
4730 
4731 	/* timer */
4732 	CHECK_OFFSET(si_tid);
4733 	CHECK_OFFSET(si_overrun);
4734 	CHECK_OFFSET(si_value);
4735 
4736 	/* rt */
4737 	CHECK_OFFSET(si_pid);
4738 	CHECK_OFFSET(si_uid);
4739 	CHECK_OFFSET(si_value);
4740 
4741 	/* sigchld */
4742 	CHECK_OFFSET(si_pid);
4743 	CHECK_OFFSET(si_uid);
4744 	CHECK_OFFSET(si_status);
4745 	CHECK_OFFSET(si_utime);
4746 	CHECK_OFFSET(si_stime);
4747 
4748 	/* sigfault */
4749 	CHECK_OFFSET(si_addr);
4750 	CHECK_OFFSET(si_trapno);
4751 	CHECK_OFFSET(si_addr_lsb);
4752 	CHECK_OFFSET(si_lower);
4753 	CHECK_OFFSET(si_upper);
4754 	CHECK_OFFSET(si_pkey);
4755 	CHECK_OFFSET(si_perf_data);
4756 	CHECK_OFFSET(si_perf_type);
4757 	CHECK_OFFSET(si_perf_flags);
4758 
4759 	/* sigpoll */
4760 	CHECK_OFFSET(si_band);
4761 	CHECK_OFFSET(si_fd);
4762 
4763 	/* sigsys */
4764 	CHECK_OFFSET(si_call_addr);
4765 	CHECK_OFFSET(si_syscall);
4766 	CHECK_OFFSET(si_arch);
4767 #undef CHECK_OFFSET
4768 
4769 	/* usb asyncio */
4770 	BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4771 		     offsetof(struct siginfo, si_addr));
4772 	if (sizeof(int) == sizeof(void __user *)) {
4773 		BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4774 			     sizeof(void __user *));
4775 	} else {
4776 		BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4777 			      sizeof_field(struct siginfo, si_uid)) !=
4778 			     sizeof(void __user *));
4779 		BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4780 			     offsetof(struct siginfo, si_uid));
4781 	}
4782 #ifdef CONFIG_COMPAT
4783 	BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4784 		     offsetof(struct compat_siginfo, si_addr));
4785 	BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4786 		     sizeof(compat_uptr_t));
4787 	BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4788 		     sizeof_field(struct siginfo, si_pid));
4789 #endif
4790 }
4791 
4792 #if defined(CONFIG_SYSCTL)
4793 static struct ctl_table signal_debug_table[] = {
4794 #ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4795 	{
4796 		.procname	= "exception-trace",
4797 		.data		= &show_unhandled_signals,
4798 		.maxlen		= sizeof(int),
4799 		.mode		= 0644,
4800 		.proc_handler	= proc_dointvec
4801 	},
4802 #endif
4803 	{ }
4804 };
4805 
init_signal_sysctls(void)4806 static int __init init_signal_sysctls(void)
4807 {
4808 	register_sysctl_init("debug", signal_debug_table);
4809 	return 0;
4810 }
4811 early_initcall(init_signal_sysctls);
4812 #endif /* CONFIG_SYSCTL */
4813 
signals_init(void)4814 void __init signals_init(void)
4815 {
4816 	siginfo_buildtime_checks();
4817 
4818 	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4819 }
4820 
4821 #ifdef CONFIG_KGDB_KDB
4822 #include <linux/kdb.h>
4823 /*
4824  * kdb_send_sig - Allows kdb to send signals without exposing
4825  * signal internals.  This function checks if the required locks are
4826  * available before calling the main signal code, to avoid kdb
4827  * deadlocks.
4828  */
kdb_send_sig(struct task_struct * t,int sig)4829 void kdb_send_sig(struct task_struct *t, int sig)
4830 {
4831 	static struct task_struct *kdb_prev_t;
4832 	int new_t, ret;
4833 	if (!spin_trylock(&t->sighand->siglock)) {
4834 		kdb_printf("Can't do kill command now.\n"
4835 			   "The sigmask lock is held somewhere else in "
4836 			   "kernel, try again later\n");
4837 		return;
4838 	}
4839 	new_t = kdb_prev_t != t;
4840 	kdb_prev_t = t;
4841 	if (!task_is_running(t) && new_t) {
4842 		spin_unlock(&t->sighand->siglock);
4843 		kdb_printf("Process is not RUNNING, sending a signal from "
4844 			   "kdb risks deadlock\n"
4845 			   "on the run queue locks. "
4846 			   "The signal has _not_ been sent.\n"
4847 			   "Reissue the kill command if you want to risk "
4848 			   "the deadlock.\n");
4849 		return;
4850 	}
4851 	ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4852 	spin_unlock(&t->sighand->siglock);
4853 	if (ret)
4854 		kdb_printf("Fail to deliver Signal %d to process %d.\n",
4855 			   sig, t->pid);
4856 	else
4857 		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4858 }
4859 #endif	/* CONFIG_KGDB_KDB */
4860