Line data Source code
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/proc_fs.h>
26 : #include <linux/tty.h>
27 : #include <linux/binfmts.h>
28 : #include <linux/coredump.h>
29 : #include <linux/security.h>
30 : #include <linux/syscalls.h>
31 : #include <linux/ptrace.h>
32 : #include <linux/signal.h>
33 : #include <linux/signalfd.h>
34 : #include <linux/ratelimit.h>
35 : #include <linux/task_work.h>
36 : #include <linux/capability.h>
37 : #include <linux/freezer.h>
38 : #include <linux/pid_namespace.h>
39 : #include <linux/nsproxy.h>
40 : #include <linux/user_namespace.h>
41 : #include <linux/uprobes.h>
42 : #include <linux/compat.h>
43 : #include <linux/cn_proc.h>
44 : #include <linux/compiler.h>
45 : #include <linux/posix-timers.h>
46 : #include <linux/cgroup.h>
47 : #include <linux/audit.h>
48 :
49 : #define CREATE_TRACE_POINTS
50 : #include <trace/events/signal.h>
51 :
52 : #include <asm/param.h>
53 : #include <linux/uaccess.h>
54 : #include <asm/unistd.h>
55 : #include <asm/siginfo.h>
56 : #include <asm/cacheflush.h>
57 : #include <asm/syscall.h> /* for syscall_get_* */
58 :
59 : /*
60 : * SLAB caches for signal bits.
61 : */
62 :
63 : static struct kmem_cache *sigqueue_cachep;
64 :
65 : int print_fatal_signals __read_mostly;
66 :
67 : static void __user *sig_handler(struct task_struct *t, int sig)
68 : {
69 0 : return t->sighand->action[sig - 1].sa.sa_handler;
70 : }
71 :
72 : static inline bool sig_handler_ignored(void __user *handler, int sig)
73 : {
74 : /* Is it explicitly or implicitly ignored? */
75 0 : return handler == SIG_IGN ||
76 0 : (handler == SIG_DFL && sig_kernel_ignore(sig));
77 : }
78 :
79 0 : static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
80 : {
81 : void __user *handler;
82 :
83 0 : handler = sig_handler(t, sig);
84 :
85 : /* SIGKILL and SIGSTOP may not be sent to the global init */
86 0 : if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
87 : return true;
88 :
89 0 : if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
90 0 : handler == SIG_DFL && !(force && sig_kernel_only(sig)))
91 : return true;
92 :
93 : /* Only allow kernel generated signals to this kthread */
94 0 : if (unlikely((t->flags & PF_KTHREAD) &&
95 : (handler == SIG_KTHREAD_KERNEL) && !force))
96 : return true;
97 :
98 0 : return sig_handler_ignored(handler, sig);
99 : }
100 :
101 0 : static bool sig_ignored(struct task_struct *t, int sig, bool force)
102 : {
103 : /*
104 : * Blocked signals are never ignored, since the
105 : * signal handler may change by the time it is
106 : * unblocked.
107 : */
108 0 : if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
109 : return false;
110 :
111 : /*
112 : * Tracers may want to know about even ignored signal unless it
113 : * is SIGKILL which can't be reported anyway but can be ignored
114 : * by SIGNAL_UNKILLABLE task.
115 : */
116 0 : if (t->ptrace && sig != SIGKILL)
117 : return false;
118 :
119 0 : return sig_task_ignored(t, sig, force);
120 : }
121 :
122 : /*
123 : * Re-calculate pending state from the set of locally pending
124 : * signals, globally pending signals, and blocked signals.
125 : */
126 : static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
127 : {
128 : unsigned long ready;
129 : long i;
130 :
131 : switch (_NSIG_WORDS) {
132 : default:
133 : for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
134 : ready |= signal->sig[i] &~ blocked->sig[i];
135 : break;
136 :
137 : case 4: ready = signal->sig[3] &~ blocked->sig[3];
138 : ready |= signal->sig[2] &~ blocked->sig[2];
139 : ready |= signal->sig[1] &~ blocked->sig[1];
140 : ready |= signal->sig[0] &~ blocked->sig[0];
141 : break;
142 :
143 : case 2: ready = signal->sig[1] &~ blocked->sig[1];
144 : ready |= signal->sig[0] &~ blocked->sig[0];
145 : break;
146 :
147 428 : case 1: ready = signal->sig[0] &~ blocked->sig[0];
148 : }
149 : return ready != 0;
150 : }
151 :
152 : #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
153 :
154 : static bool recalc_sigpending_tsk(struct task_struct *t)
155 : {
156 428 : if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
157 642 : PENDING(&t->pending, &t->blocked) ||
158 428 : PENDING(&t->signal->shared_pending, &t->blocked) ||
159 : cgroup_task_frozen(t)) {
160 0 : set_tsk_thread_flag(t, TIF_SIGPENDING);
161 : return true;
162 : }
163 :
164 : /*
165 : * We must never clear the flag in another thread, or in current
166 : * when it's possible the current syscall is returning -ERESTART*.
167 : * So we don't clear it here, and only callers who know they should do.
168 : */
169 : return false;
170 : }
171 :
172 : /*
173 : * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
174 : * This is superfluous when called on current, the wakeup is a harmless no-op.
175 : */
176 0 : void recalc_sigpending_and_wake(struct task_struct *t)
177 : {
178 0 : if (recalc_sigpending_tsk(t))
179 : signal_wake_up(t, 0);
180 0 : }
181 :
182 214 : void recalc_sigpending(void)
183 : {
184 856 : if (!recalc_sigpending_tsk(current) && !freezing(current))
185 214 : clear_thread_flag(TIF_SIGPENDING);
186 :
187 214 : }
188 : EXPORT_SYMBOL(recalc_sigpending);
189 :
190 107 : void calculate_sigpending(void)
191 : {
192 : /* Have any signals or users of TIF_SIGPENDING been delayed
193 : * until after fork?
194 : */
195 214 : spin_lock_irq(¤t->sighand->siglock);
196 214 : set_tsk_thread_flag(current, TIF_SIGPENDING);
197 107 : recalc_sigpending();
198 214 : spin_unlock_irq(¤t->sighand->siglock);
199 107 : }
200 :
201 : /* Given the mask, find the first available signal that should be serviced. */
202 :
203 : #define SYNCHRONOUS_MASK \
204 : (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
205 : sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
206 :
207 0 : int next_signal(struct sigpending *pending, sigset_t *mask)
208 : {
209 : unsigned long i, *s, *m, x;
210 0 : int sig = 0;
211 :
212 0 : s = pending->signal.sig;
213 0 : m = mask->sig;
214 :
215 : /*
216 : * Handle the first word specially: it contains the
217 : * synchronous signals that need to be dequeued first.
218 : */
219 0 : x = *s &~ *m;
220 0 : if (x) {
221 0 : if (x & SYNCHRONOUS_MASK)
222 0 : x &= SYNCHRONOUS_MASK;
223 0 : sig = ffz(~x) + 1;
224 0 : return sig;
225 : }
226 :
227 : switch (_NSIG_WORDS) {
228 : default:
229 : for (i = 1; i < _NSIG_WORDS; ++i) {
230 : x = *++s &~ *++m;
231 : if (!x)
232 : continue;
233 : sig = ffz(~x) + i*_NSIG_BPW + 1;
234 : break;
235 : }
236 : break;
237 :
238 : case 2:
239 : x = s[1] &~ m[1];
240 : if (!x)
241 : break;
242 : sig = ffz(~x) + _NSIG_BPW + 1;
243 : break;
244 :
245 : case 1:
246 : /* Nothing to do */
247 : break;
248 : }
249 :
250 : return sig;
251 : }
252 :
253 0 : static inline void print_dropped_signal(int sig)
254 : {
255 : static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
256 :
257 0 : if (!print_fatal_signals)
258 : return;
259 :
260 0 : if (!__ratelimit(&ratelimit_state))
261 : return;
262 :
263 0 : pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
264 : current->comm, current->pid, sig);
265 : }
266 :
267 : /**
268 : * task_set_jobctl_pending - set jobctl pending bits
269 : * @task: target task
270 : * @mask: pending bits to set
271 : *
272 : * Clear @mask from @task->jobctl. @mask must be subset of
273 : * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
274 : * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
275 : * cleared. If @task is already being killed or exiting, this function
276 : * becomes noop.
277 : *
278 : * CONTEXT:
279 : * Must be called with @task->sighand->siglock held.
280 : *
281 : * RETURNS:
282 : * %true if @mask is set, %false if made noop because @task was dying.
283 : */
284 0 : bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
285 : {
286 0 : BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
287 : JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
288 0 : BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
289 :
290 0 : if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
291 : return false;
292 :
293 0 : if (mask & JOBCTL_STOP_SIGMASK)
294 0 : task->jobctl &= ~JOBCTL_STOP_SIGMASK;
295 :
296 0 : task->jobctl |= mask;
297 0 : return true;
298 : }
299 :
300 : /**
301 : * task_clear_jobctl_trapping - clear jobctl trapping bit
302 : * @task: target task
303 : *
304 : * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
305 : * Clear it and wake up the ptracer. Note that we don't need any further
306 : * locking. @task->siglock guarantees that @task->parent points to the
307 : * ptracer.
308 : *
309 : * CONTEXT:
310 : * Must be called with @task->sighand->siglock held.
311 : */
312 0 : void task_clear_jobctl_trapping(struct task_struct *task)
313 : {
314 0 : if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
315 0 : task->jobctl &= ~JOBCTL_TRAPPING;
316 0 : smp_mb(); /* advised by wake_up_bit() */
317 0 : wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
318 : }
319 0 : }
320 :
321 : /**
322 : * task_clear_jobctl_pending - clear jobctl pending bits
323 : * @task: target task
324 : * @mask: pending bits to clear
325 : *
326 : * Clear @mask from @task->jobctl. @mask must be subset of
327 : * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
328 : * STOP bits are cleared together.
329 : *
330 : * If clearing of @mask leaves no stop or trap pending, this function calls
331 : * task_clear_jobctl_trapping().
332 : *
333 : * CONTEXT:
334 : * Must be called with @task->sighand->siglock held.
335 : */
336 0 : void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
337 : {
338 0 : BUG_ON(mask & ~JOBCTL_PENDING_MASK);
339 :
340 0 : if (mask & JOBCTL_STOP_PENDING)
341 0 : mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
342 :
343 0 : task->jobctl &= ~mask;
344 :
345 0 : if (!(task->jobctl & JOBCTL_PENDING_MASK))
346 : task_clear_jobctl_trapping(task);
347 0 : }
348 :
349 : /**
350 : * task_participate_group_stop - participate in a group stop
351 : * @task: task participating in a group stop
352 : *
353 : * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
354 : * Group stop states are cleared and the group stop count is consumed if
355 : * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
356 : * stop, the appropriate `SIGNAL_*` flags are set.
357 : *
358 : * CONTEXT:
359 : * Must be called with @task->sighand->siglock held.
360 : *
361 : * RETURNS:
362 : * %true if group stop completion should be notified to the parent, %false
363 : * otherwise.
364 : */
365 0 : static bool task_participate_group_stop(struct task_struct *task)
366 : {
367 0 : struct signal_struct *sig = task->signal;
368 0 : bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
369 :
370 0 : WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
371 :
372 0 : task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
373 :
374 0 : if (!consume)
375 : return false;
376 :
377 0 : if (!WARN_ON_ONCE(sig->group_stop_count == 0))
378 0 : sig->group_stop_count--;
379 :
380 : /*
381 : * Tell the caller to notify completion iff we are entering into a
382 : * fresh group stop. Read comment in do_signal_stop() for details.
383 : */
384 0 : if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
385 0 : signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
386 0 : return true;
387 : }
388 : return false;
389 : }
390 :
391 0 : void task_join_group_stop(struct task_struct *task)
392 : {
393 0 : unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
394 0 : struct signal_struct *sig = current->signal;
395 :
396 0 : if (sig->group_stop_count) {
397 0 : sig->group_stop_count++;
398 0 : mask |= JOBCTL_STOP_CONSUME;
399 0 : } else if (!(sig->flags & SIGNAL_STOP_STOPPED))
400 : return;
401 :
402 : /* Have the new thread join an on-going signal group stop */
403 0 : task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
404 : }
405 :
406 : /*
407 : * allocate a new signal queue record
408 : * - this may be called without locks if and only if t == current, otherwise an
409 : * appropriate lock must be held to stop the target task from exiting
410 : */
411 : static struct sigqueue *
412 0 : __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
413 : int override_rlimit, const unsigned int sigqueue_flags)
414 : {
415 0 : struct sigqueue *q = NULL;
416 0 : struct ucounts *ucounts = NULL;
417 : long sigpending;
418 :
419 : /*
420 : * Protect access to @t credentials. This can go away when all
421 : * callers hold rcu read lock.
422 : *
423 : * NOTE! A pending signal will hold on to the user refcount,
424 : * and we get/put the refcount only when the sigpending count
425 : * changes from/to zero.
426 : */
427 : rcu_read_lock();
428 0 : ucounts = task_ucounts(t);
429 0 : sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
430 : rcu_read_unlock();
431 0 : if (!sigpending)
432 : return NULL;
433 :
434 0 : if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
435 0 : q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
436 : } else {
437 0 : print_dropped_signal(sig);
438 : }
439 :
440 0 : if (unlikely(q == NULL)) {
441 0 : dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
442 : } else {
443 0 : INIT_LIST_HEAD(&q->list);
444 0 : q->flags = sigqueue_flags;
445 0 : q->ucounts = ucounts;
446 : }
447 : return q;
448 : }
449 :
450 0 : static void __sigqueue_free(struct sigqueue *q)
451 : {
452 0 : if (q->flags & SIGQUEUE_PREALLOC)
453 : return;
454 0 : if (q->ucounts) {
455 0 : dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
456 0 : q->ucounts = NULL;
457 : }
458 0 : kmem_cache_free(sigqueue_cachep, q);
459 : }
460 :
461 188 : void flush_sigqueue(struct sigpending *queue)
462 : {
463 : struct sigqueue *q;
464 :
465 188 : sigemptyset(&queue->signal);
466 376 : while (!list_empty(&queue->list)) {
467 0 : q = list_entry(queue->list.next, struct sigqueue , list);
468 0 : list_del_init(&q->list);
469 0 : __sigqueue_free(q);
470 : }
471 188 : }
472 :
473 : /*
474 : * Flush all pending signals for this kthread.
475 : */
476 1 : void flush_signals(struct task_struct *t)
477 : {
478 : unsigned long flags;
479 :
480 1 : spin_lock_irqsave(&t->sighand->siglock, flags);
481 2 : clear_tsk_thread_flag(t, TIF_SIGPENDING);
482 1 : flush_sigqueue(&t->pending);
483 1 : flush_sigqueue(&t->signal->shared_pending);
484 2 : spin_unlock_irqrestore(&t->sighand->siglock, flags);
485 1 : }
486 : EXPORT_SYMBOL(flush_signals);
487 :
488 : #ifdef CONFIG_POSIX_TIMERS
489 0 : static void __flush_itimer_signals(struct sigpending *pending)
490 : {
491 : sigset_t signal, retain;
492 : struct sigqueue *q, *n;
493 :
494 0 : signal = pending->signal;
495 0 : sigemptyset(&retain);
496 :
497 0 : list_for_each_entry_safe(q, n, &pending->list, list) {
498 0 : int sig = q->info.si_signo;
499 :
500 0 : if (likely(q->info.si_code != SI_TIMER)) {
501 : sigaddset(&retain, sig);
502 : } else {
503 0 : sigdelset(&signal, sig);
504 0 : list_del_init(&q->list);
505 0 : __sigqueue_free(q);
506 : }
507 : }
508 :
509 0 : sigorsets(&pending->signal, &signal, &retain);
510 0 : }
511 :
512 0 : void flush_itimer_signals(void)
513 : {
514 0 : struct task_struct *tsk = current;
515 : unsigned long flags;
516 :
517 0 : spin_lock_irqsave(&tsk->sighand->siglock, flags);
518 0 : __flush_itimer_signals(&tsk->pending);
519 0 : __flush_itimer_signals(&tsk->signal->shared_pending);
520 0 : spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
521 0 : }
522 : #endif
523 :
524 1 : void ignore_signals(struct task_struct *t)
525 : {
526 : int i;
527 :
528 65 : for (i = 0; i < _NSIG; ++i)
529 64 : t->sighand->action[i].sa.sa_handler = SIG_IGN;
530 :
531 1 : flush_signals(t);
532 1 : }
533 :
534 : /*
535 : * Flush all handlers for a task.
536 : */
537 :
538 : void
539 0 : flush_signal_handlers(struct task_struct *t, int force_default)
540 : {
541 : int i;
542 0 : struct k_sigaction *ka = &t->sighand->action[0];
543 0 : for (i = _NSIG ; i != 0 ; i--) {
544 0 : if (force_default || ka->sa.sa_handler != SIG_IGN)
545 0 : ka->sa.sa_handler = SIG_DFL;
546 0 : ka->sa.sa_flags = 0;
547 : #ifdef __ARCH_HAS_SA_RESTORER
548 0 : ka->sa.sa_restorer = NULL;
549 : #endif
550 0 : sigemptyset(&ka->sa.sa_mask);
551 0 : ka++;
552 : }
553 0 : }
554 :
555 0 : bool unhandled_signal(struct task_struct *tsk, int sig)
556 : {
557 0 : void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
558 0 : if (is_global_init(tsk))
559 : return true;
560 :
561 0 : if (handler != SIG_IGN && handler != SIG_DFL)
562 : return false;
563 :
564 : /* if ptraced, let the tracer determine */
565 0 : return !tsk->ptrace;
566 : }
567 :
568 0 : static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
569 : bool *resched_timer)
570 : {
571 0 : struct sigqueue *q, *first = NULL;
572 :
573 : /*
574 : * Collect the siginfo appropriate to this signal. Check if
575 : * there is another siginfo for the same signal.
576 : */
577 0 : list_for_each_entry(q, &list->list, list) {
578 0 : if (q->info.si_signo == sig) {
579 0 : if (first)
580 : goto still_pending;
581 : first = q;
582 : }
583 : }
584 :
585 0 : sigdelset(&list->signal, sig);
586 :
587 0 : if (first) {
588 : still_pending:
589 0 : list_del_init(&first->list);
590 0 : copy_siginfo(info, &first->info);
591 :
592 0 : *resched_timer =
593 0 : (first->flags & SIGQUEUE_PREALLOC) &&
594 0 : (info->si_code == SI_TIMER) &&
595 0 : (info->si_sys_private);
596 :
597 0 : __sigqueue_free(first);
598 : } else {
599 : /*
600 : * Ok, it wasn't in the queue. This must be
601 : * a fast-pathed signal or we must have been
602 : * out of queue space. So zero out the info.
603 : */
604 0 : clear_siginfo(info);
605 0 : info->si_signo = sig;
606 0 : info->si_errno = 0;
607 0 : info->si_code = SI_USER;
608 0 : info->si_pid = 0;
609 0 : info->si_uid = 0;
610 : }
611 0 : }
612 :
613 0 : static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
614 : kernel_siginfo_t *info, bool *resched_timer)
615 : {
616 0 : int sig = next_signal(pending, mask);
617 :
618 0 : if (sig)
619 0 : collect_signal(sig, pending, info, resched_timer);
620 0 : return sig;
621 : }
622 :
623 : /*
624 : * Dequeue a signal and return the element to the caller, which is
625 : * expected to free it.
626 : *
627 : * All callers have to hold the siglock.
628 : */
629 0 : int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
630 : kernel_siginfo_t *info, enum pid_type *type)
631 : {
632 0 : bool resched_timer = false;
633 : int signr;
634 :
635 : /* We only dequeue private signals from ourselves, we don't let
636 : * signalfd steal them
637 : */
638 0 : *type = PIDTYPE_PID;
639 0 : signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
640 0 : if (!signr) {
641 0 : *type = PIDTYPE_TGID;
642 0 : signr = __dequeue_signal(&tsk->signal->shared_pending,
643 : mask, info, &resched_timer);
644 : #ifdef CONFIG_POSIX_TIMERS
645 : /*
646 : * itimer signal ?
647 : *
648 : * itimers are process shared and we restart periodic
649 : * itimers in the signal delivery path to prevent DoS
650 : * attacks in the high resolution timer case. This is
651 : * compliant with the old way of self-restarting
652 : * itimers, as the SIGALRM is a legacy signal and only
653 : * queued once. Changing the restart behaviour to
654 : * restart the timer in the signal dequeue path is
655 : * reducing the timer noise on heavy loaded !highres
656 : * systems too.
657 : */
658 0 : if (unlikely(signr == SIGALRM)) {
659 0 : struct hrtimer *tmr = &tsk->signal->real_timer;
660 :
661 0 : if (!hrtimer_is_queued(tmr) &&
662 0 : tsk->signal->it_real_incr != 0) {
663 0 : hrtimer_forward(tmr, tmr->base->get_time(),
664 : tsk->signal->it_real_incr);
665 : hrtimer_restart(tmr);
666 : }
667 : }
668 : #endif
669 : }
670 :
671 0 : recalc_sigpending();
672 0 : if (!signr)
673 : return 0;
674 :
675 0 : if (unlikely(sig_kernel_stop(signr))) {
676 : /*
677 : * Set a marker that we have dequeued a stop signal. Our
678 : * caller might release the siglock and then the pending
679 : * stop signal it is about to process is no longer in the
680 : * pending bitmasks, but must still be cleared by a SIGCONT
681 : * (and overruled by a SIGKILL). So those cases clear this
682 : * shared flag after we've set it. Note that this flag may
683 : * remain set after the signal we return is ignored or
684 : * handled. That doesn't matter because its only purpose
685 : * is to alert stop-signal processing code when another
686 : * processor has come along and cleared the flag.
687 : */
688 0 : current->jobctl |= JOBCTL_STOP_DEQUEUED;
689 : }
690 : #ifdef CONFIG_POSIX_TIMERS
691 0 : if (resched_timer) {
692 : /*
693 : * Release the siglock to ensure proper locking order
694 : * of timer locks outside of siglocks. Note, we leave
695 : * irqs disabled here, since the posix-timers code is
696 : * about to disable them again anyway.
697 : */
698 0 : spin_unlock(&tsk->sighand->siglock);
699 0 : posixtimer_rearm(info);
700 0 : spin_lock(&tsk->sighand->siglock);
701 :
702 : /* Don't expose the si_sys_private value to userspace */
703 0 : info->si_sys_private = 0;
704 : }
705 : #endif
706 : return signr;
707 : }
708 : EXPORT_SYMBOL_GPL(dequeue_signal);
709 :
710 0 : static int dequeue_synchronous_signal(kernel_siginfo_t *info)
711 : {
712 0 : struct task_struct *tsk = current;
713 0 : struct sigpending *pending = &tsk->pending;
714 0 : struct sigqueue *q, *sync = NULL;
715 :
716 : /*
717 : * Might a synchronous signal be in the queue?
718 : */
719 0 : if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
720 : return 0;
721 :
722 : /*
723 : * Return the first synchronous signal in the queue.
724 : */
725 0 : list_for_each_entry(q, &pending->list, list) {
726 : /* Synchronous signals have a positive si_code */
727 0 : if ((q->info.si_code > SI_USER) &&
728 0 : (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
729 0 : sync = q;
730 : goto next;
731 : }
732 : }
733 : return 0;
734 : next:
735 : /*
736 : * Check if there is another siginfo for the same signal.
737 : */
738 0 : list_for_each_entry_continue(q, &pending->list, list) {
739 0 : if (q->info.si_signo == sync->info.si_signo)
740 : goto still_pending;
741 : }
742 :
743 0 : sigdelset(&pending->signal, sync->info.si_signo);
744 0 : recalc_sigpending();
745 : still_pending:
746 0 : list_del_init(&sync->list);
747 0 : copy_siginfo(info, &sync->info);
748 0 : __sigqueue_free(sync);
749 0 : return info->si_signo;
750 : }
751 :
752 : /*
753 : * Tell a process that it has a new active signal..
754 : *
755 : * NOTE! we rely on the previous spin_lock to
756 : * lock interrupts for us! We can only be called with
757 : * "siglock" held, and the local interrupt must
758 : * have been disabled when that got acquired!
759 : *
760 : * No need to set need_resched since signal event passing
761 : * goes through ->blocked
762 : */
763 0 : void signal_wake_up_state(struct task_struct *t, unsigned int state)
764 : {
765 0 : set_tsk_thread_flag(t, TIF_SIGPENDING);
766 : /*
767 : * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
768 : * case. We don't check t->state here because there is a race with it
769 : * executing another processor and just now entering stopped state.
770 : * By using wake_up_state, we ensure the process will wake up and
771 : * handle its death signal.
772 : */
773 0 : if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
774 : kick_process(t);
775 0 : }
776 :
777 : /*
778 : * Remove signals in mask from the pending set and queue.
779 : * Returns 1 if any signals were found.
780 : *
781 : * All callers must be holding the siglock.
782 : */
783 0 : static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
784 : {
785 : struct sigqueue *q, *n;
786 : sigset_t m;
787 :
788 0 : sigandsets(&m, mask, &s->signal);
789 0 : if (sigisemptyset(&m))
790 : return;
791 :
792 0 : sigandnsets(&s->signal, &s->signal, mask);
793 0 : list_for_each_entry_safe(q, n, &s->list, list) {
794 0 : if (sigismember(mask, q->info.si_signo)) {
795 0 : list_del_init(&q->list);
796 0 : __sigqueue_free(q);
797 : }
798 : }
799 : }
800 :
801 : static inline int is_si_special(const struct kernel_siginfo *info)
802 : {
803 : return info <= SEND_SIG_PRIV;
804 : }
805 :
806 : static inline bool si_fromuser(const struct kernel_siginfo *info)
807 : {
808 0 : return info == SEND_SIG_NOINFO ||
809 0 : (!is_si_special(info) && SI_FROMUSER(info));
810 : }
811 :
812 : /*
813 : * called with RCU read lock from check_kill_permission()
814 : */
815 0 : static bool kill_ok_by_cred(struct task_struct *t)
816 : {
817 0 : const struct cred *cred = current_cred();
818 0 : const struct cred *tcred = __task_cred(t);
819 :
820 0 : return uid_eq(cred->euid, tcred->suid) ||
821 0 : uid_eq(cred->euid, tcred->uid) ||
822 0 : uid_eq(cred->uid, tcred->suid) ||
823 0 : uid_eq(cred->uid, tcred->uid) ||
824 0 : ns_capable(tcred->user_ns, CAP_KILL);
825 : }
826 :
827 : /*
828 : * Bad permissions for sending the signal
829 : * - the caller must hold the RCU read lock
830 : */
831 0 : static int check_kill_permission(int sig, struct kernel_siginfo *info,
832 : struct task_struct *t)
833 : {
834 : struct pid *sid;
835 : int error;
836 :
837 0 : if (!valid_signal(sig))
838 : return -EINVAL;
839 :
840 0 : if (!si_fromuser(info))
841 : return 0;
842 :
843 0 : error = audit_signal_info(sig, t); /* Let audit system see the signal */
844 : if (error)
845 : return error;
846 :
847 0 : if (!same_thread_group(current, t) &&
848 0 : !kill_ok_by_cred(t)) {
849 0 : switch (sig) {
850 : case SIGCONT:
851 0 : sid = task_session(t);
852 : /*
853 : * We don't return the error if sid == NULL. The
854 : * task was unhashed, the caller must notice this.
855 : */
856 0 : if (!sid || sid == task_session(current))
857 : break;
858 : fallthrough;
859 : default:
860 : return -EPERM;
861 : }
862 : }
863 :
864 : return security_task_kill(t, info, sig, NULL);
865 : }
866 :
867 : /**
868 : * ptrace_trap_notify - schedule trap to notify ptracer
869 : * @t: tracee wanting to notify tracer
870 : *
871 : * This function schedules sticky ptrace trap which is cleared on the next
872 : * TRAP_STOP to notify ptracer of an event. @t must have been seized by
873 : * ptracer.
874 : *
875 : * If @t is running, STOP trap will be taken. If trapped for STOP and
876 : * ptracer is listening for events, tracee is woken up so that it can
877 : * re-trap for the new event. If trapped otherwise, STOP trap will be
878 : * eventually taken without returning to userland after the existing traps
879 : * are finished by PTRACE_CONT.
880 : *
881 : * CONTEXT:
882 : * Must be called with @task->sighand->siglock held.
883 : */
884 0 : static void ptrace_trap_notify(struct task_struct *t)
885 : {
886 0 : WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
887 : assert_spin_locked(&t->sighand->siglock);
888 :
889 0 : task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
890 0 : ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
891 0 : }
892 :
893 : /*
894 : * Handle magic process-wide effects of stop/continue signals. Unlike
895 : * the signal actions, these happen immediately at signal-generation
896 : * time regardless of blocking, ignoring, or handling. This does the
897 : * actual continuing for SIGCONT, but not the actual stopping for stop
898 : * signals. The process stop is done as a signal action for SIG_DFL.
899 : *
900 : * Returns true if the signal should be actually delivered, otherwise
901 : * it should be dropped.
902 : */
903 0 : static bool prepare_signal(int sig, struct task_struct *p, bool force)
904 : {
905 0 : struct signal_struct *signal = p->signal;
906 : struct task_struct *t;
907 : sigset_t flush;
908 :
909 0 : if (signal->flags & SIGNAL_GROUP_EXIT) {
910 0 : if (signal->core_state)
911 0 : return sig == SIGKILL;
912 : /*
913 : * The process is in the middle of dying, nothing to do.
914 : */
915 0 : } else if (sig_kernel_stop(sig)) {
916 : /*
917 : * This is a stop signal. Remove SIGCONT from all queues.
918 : */
919 0 : siginitset(&flush, sigmask(SIGCONT));
920 0 : flush_sigqueue_mask(&flush, &signal->shared_pending);
921 0 : for_each_thread(p, t)
922 0 : flush_sigqueue_mask(&flush, &t->pending);
923 0 : } else if (sig == SIGCONT) {
924 : unsigned int why;
925 : /*
926 : * Remove all stop signals from all queues, wake all threads.
927 : */
928 0 : siginitset(&flush, SIG_KERNEL_STOP_MASK);
929 0 : flush_sigqueue_mask(&flush, &signal->shared_pending);
930 0 : for_each_thread(p, t) {
931 0 : flush_sigqueue_mask(&flush, &t->pending);
932 0 : task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
933 0 : if (likely(!(t->ptrace & PT_SEIZED)))
934 0 : wake_up_state(t, __TASK_STOPPED);
935 : else
936 0 : ptrace_trap_notify(t);
937 : }
938 :
939 : /*
940 : * Notify the parent with CLD_CONTINUED if we were stopped.
941 : *
942 : * If we were in the middle of a group stop, we pretend it
943 : * was already finished, and then continued. Since SIGCHLD
944 : * doesn't queue we report only CLD_STOPPED, as if the next
945 : * CLD_CONTINUED was dropped.
946 : */
947 0 : why = 0;
948 0 : if (signal->flags & SIGNAL_STOP_STOPPED)
949 : why |= SIGNAL_CLD_CONTINUED;
950 0 : else if (signal->group_stop_count)
951 0 : why |= SIGNAL_CLD_STOPPED;
952 :
953 0 : if (why) {
954 : /*
955 : * The first thread which returns from do_signal_stop()
956 : * will take ->siglock, notice SIGNAL_CLD_MASK, and
957 : * notify its parent. See get_signal().
958 : */
959 0 : signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
960 0 : signal->group_stop_count = 0;
961 0 : signal->group_exit_code = 0;
962 : }
963 : }
964 :
965 0 : return !sig_ignored(p, sig, force);
966 : }
967 :
968 : /*
969 : * Test if P wants to take SIG. After we've checked all threads with this,
970 : * it's equivalent to finding no threads not blocking SIG. Any threads not
971 : * blocking SIG were ruled out because they are not running and already
972 : * have pending signals. Such threads will dequeue from the shared queue
973 : * as soon as they're available, so putting the signal on the shared queue
974 : * will be equivalent to sending it to one such thread.
975 : */
976 0 : static inline bool wants_signal(int sig, struct task_struct *p)
977 : {
978 0 : if (sigismember(&p->blocked, sig))
979 : return false;
980 :
981 0 : if (p->flags & PF_EXITING)
982 : return false;
983 :
984 0 : if (sig == SIGKILL)
985 : return true;
986 :
987 0 : if (task_is_stopped_or_traced(p))
988 : return false;
989 :
990 0 : return task_curr(p) || !task_sigpending(p);
991 : }
992 :
993 0 : static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
994 : {
995 0 : struct signal_struct *signal = p->signal;
996 : struct task_struct *t;
997 :
998 : /*
999 : * Now find a thread we can wake up to take the signal off the queue.
1000 : *
1001 : * If the main thread wants the signal, it gets first crack.
1002 : * Probably the least surprising to the average bear.
1003 : */
1004 0 : if (wants_signal(sig, p))
1005 : t = p;
1006 0 : else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1007 : /*
1008 : * There is just one thread and it does not need to be woken.
1009 : * It will dequeue unblocked signals before it runs again.
1010 : */
1011 : return;
1012 : else {
1013 : /*
1014 : * Otherwise try to find a suitable thread.
1015 : */
1016 0 : t = signal->curr_target;
1017 0 : while (!wants_signal(sig, t)) {
1018 0 : t = next_thread(t);
1019 0 : if (t == signal->curr_target)
1020 : /*
1021 : * No thread needs to be woken.
1022 : * Any eligible threads will see
1023 : * the signal in the queue soon.
1024 : */
1025 : return;
1026 : }
1027 0 : signal->curr_target = t;
1028 : }
1029 :
1030 : /*
1031 : * Found a killable thread. If the signal will be fatal,
1032 : * then start taking the whole group down immediately.
1033 : */
1034 0 : if (sig_fatal(p, sig) &&
1035 0 : (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1036 0 : !sigismember(&t->real_blocked, sig) &&
1037 0 : (sig == SIGKILL || !p->ptrace)) {
1038 : /*
1039 : * This signal will be fatal to the whole group.
1040 : */
1041 0 : if (!sig_kernel_coredump(sig)) {
1042 : /*
1043 : * Start a group exit and wake everybody up.
1044 : * This way we don't have other threads
1045 : * running and doing things after a slower
1046 : * thread has the fatal signal pending.
1047 : */
1048 0 : signal->flags = SIGNAL_GROUP_EXIT;
1049 0 : signal->group_exit_code = sig;
1050 0 : signal->group_stop_count = 0;
1051 0 : t = p;
1052 : do {
1053 0 : task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1054 0 : sigaddset(&t->pending.signal, SIGKILL);
1055 0 : signal_wake_up(t, 1);
1056 0 : } while_each_thread(p, t);
1057 : return;
1058 : }
1059 : }
1060 :
1061 : /*
1062 : * The signal is already in the shared-pending queue.
1063 : * Tell the chosen thread to wake up and dequeue it.
1064 : */
1065 0 : signal_wake_up(t, sig == SIGKILL);
1066 : return;
1067 : }
1068 :
1069 : static inline bool legacy_queue(struct sigpending *signals, int sig)
1070 : {
1071 0 : return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1072 : }
1073 :
1074 0 : static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1075 : enum pid_type type, bool force)
1076 : {
1077 : struct sigpending *pending;
1078 : struct sigqueue *q;
1079 : int override_rlimit;
1080 0 : int ret = 0, result;
1081 :
1082 : assert_spin_locked(&t->sighand->siglock);
1083 :
1084 0 : result = TRACE_SIGNAL_IGNORED;
1085 0 : if (!prepare_signal(sig, t, force))
1086 : goto ret;
1087 :
1088 0 : pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1089 : /*
1090 : * Short-circuit ignored signals and support queuing
1091 : * exactly one non-rt signal, so that we can get more
1092 : * detailed information about the cause of the signal.
1093 : */
1094 0 : result = TRACE_SIGNAL_ALREADY_PENDING;
1095 0 : if (legacy_queue(pending, sig))
1096 : goto ret;
1097 :
1098 0 : result = TRACE_SIGNAL_DELIVERED;
1099 : /*
1100 : * Skip useless siginfo allocation for SIGKILL and kernel threads.
1101 : */
1102 0 : if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1103 : goto out_set;
1104 :
1105 : /*
1106 : * Real-time signals must be queued if sent by sigqueue, or
1107 : * some other real-time mechanism. It is implementation
1108 : * defined whether kill() does so. We attempt to do so, on
1109 : * the principle of least surprise, but since kill is not
1110 : * allowed to fail with EAGAIN when low on memory we just
1111 : * make sure at least one signal gets delivered and don't
1112 : * pass on the info struct.
1113 : */
1114 0 : if (sig < SIGRTMIN)
1115 0 : override_rlimit = (is_si_special(info) || info->si_code >= 0);
1116 : else
1117 : override_rlimit = 0;
1118 :
1119 0 : q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1120 :
1121 0 : if (q) {
1122 0 : list_add_tail(&q->list, &pending->list);
1123 0 : switch ((unsigned long) info) {
1124 : case (unsigned long) SEND_SIG_NOINFO:
1125 0 : clear_siginfo(&q->info);
1126 0 : q->info.si_signo = sig;
1127 0 : q->info.si_errno = 0;
1128 0 : q->info.si_code = SI_USER;
1129 0 : q->info.si_pid = task_tgid_nr_ns(current,
1130 : task_active_pid_ns(t));
1131 : rcu_read_lock();
1132 0 : q->info.si_uid =
1133 0 : from_kuid_munged(task_cred_xxx(t, user_ns),
1134 0 : current_uid());
1135 : rcu_read_unlock();
1136 : break;
1137 : case (unsigned long) SEND_SIG_PRIV:
1138 0 : clear_siginfo(&q->info);
1139 0 : q->info.si_signo = sig;
1140 0 : q->info.si_errno = 0;
1141 0 : q->info.si_code = SI_KERNEL;
1142 0 : q->info.si_pid = 0;
1143 0 : q->info.si_uid = 0;
1144 0 : break;
1145 : default:
1146 0 : copy_siginfo(&q->info, info);
1147 : break;
1148 : }
1149 0 : } else if (!is_si_special(info) &&
1150 0 : sig >= SIGRTMIN && info->si_code != SI_USER) {
1151 : /*
1152 : * Queue overflow, abort. We may abort if the
1153 : * signal was rt and sent by user using something
1154 : * other than kill().
1155 : */
1156 : result = TRACE_SIGNAL_OVERFLOW_FAIL;
1157 : ret = -EAGAIN;
1158 : goto ret;
1159 : } else {
1160 : /*
1161 : * This is a silent loss of information. We still
1162 : * send the signal, but the *info bits are lost.
1163 : */
1164 : result = TRACE_SIGNAL_LOSE_INFO;
1165 : }
1166 :
1167 : out_set:
1168 0 : signalfd_notify(t, sig);
1169 0 : sigaddset(&pending->signal, sig);
1170 :
1171 : /* Let multiprocess signals appear after on-going forks */
1172 0 : if (type > PIDTYPE_TGID) {
1173 : struct multiprocess_signals *delayed;
1174 0 : hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1175 0 : sigset_t *signal = &delayed->signal;
1176 : /* Can't queue both a stop and a continue signal */
1177 0 : if (sig == SIGCONT)
1178 : sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1179 0 : else if (sig_kernel_stop(sig))
1180 : sigdelset(signal, SIGCONT);
1181 0 : sigaddset(signal, sig);
1182 : }
1183 : }
1184 :
1185 0 : complete_signal(sig, t, type);
1186 : ret:
1187 0 : trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1188 0 : return ret;
1189 : }
1190 :
1191 0 : static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1192 : {
1193 0 : bool ret = false;
1194 0 : switch (siginfo_layout(info->si_signo, info->si_code)) {
1195 : case SIL_KILL:
1196 : case SIL_CHLD:
1197 : case SIL_RT:
1198 : ret = true;
1199 : break;
1200 : case SIL_TIMER:
1201 : case SIL_POLL:
1202 : case SIL_FAULT:
1203 : case SIL_FAULT_TRAPNO:
1204 : case SIL_FAULT_MCEERR:
1205 : case SIL_FAULT_BNDERR:
1206 : case SIL_FAULT_PKUERR:
1207 : case SIL_FAULT_PERF_EVENT:
1208 : case SIL_SYS:
1209 : ret = false;
1210 : break;
1211 : }
1212 0 : return ret;
1213 : }
1214 :
1215 0 : static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
1216 : enum pid_type type)
1217 : {
1218 : /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1219 0 : bool force = false;
1220 :
1221 0 : if (info == SEND_SIG_NOINFO) {
1222 : /* Force if sent from an ancestor pid namespace */
1223 0 : force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1224 0 : } else if (info == SEND_SIG_PRIV) {
1225 : /* Don't ignore kernel generated signals */
1226 : force = true;
1227 0 : } else if (has_si_pid_and_uid(info)) {
1228 : /* SIGKILL and SIGSTOP is special or has ids */
1229 : struct user_namespace *t_user_ns;
1230 :
1231 : rcu_read_lock();
1232 0 : t_user_ns = task_cred_xxx(t, user_ns);
1233 0 : if (current_user_ns() != t_user_ns) {
1234 0 : kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1235 0 : info->si_uid = from_kuid_munged(t_user_ns, uid);
1236 : }
1237 : rcu_read_unlock();
1238 :
1239 : /* A kernel generated signal? */
1240 0 : force = (info->si_code == SI_KERNEL);
1241 :
1242 : /* From an ancestor pid namespace? */
1243 0 : if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1244 0 : info->si_pid = 0;
1245 0 : force = true;
1246 : }
1247 : }
1248 0 : return __send_signal(sig, info, t, type, force);
1249 : }
1250 :
1251 0 : static void print_fatal_signal(int signr)
1252 : {
1253 0 : struct pt_regs *regs = signal_pt_regs();
1254 0 : pr_info("potentially unexpected fatal signal %d.\n", signr);
1255 :
1256 : #if defined(__i386__) && !defined(__arch_um__)
1257 : pr_info("code at %08lx: ", regs->ip);
1258 : {
1259 : int i;
1260 : for (i = 0; i < 16; i++) {
1261 : unsigned char insn;
1262 :
1263 : if (get_user(insn, (unsigned char *)(regs->ip + i)))
1264 : break;
1265 : pr_cont("%02x ", insn);
1266 : }
1267 : }
1268 : pr_cont("\n");
1269 : #endif
1270 0 : preempt_disable();
1271 0 : show_regs(regs);
1272 0 : preempt_enable();
1273 0 : }
1274 :
1275 0 : static int __init setup_print_fatal_signals(char *str)
1276 : {
1277 0 : get_option (&str, &print_fatal_signals);
1278 :
1279 0 : return 1;
1280 : }
1281 :
1282 : __setup("print-fatal-signals=", setup_print_fatal_signals);
1283 :
1284 : int
1285 0 : __group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1286 : {
1287 0 : return send_signal(sig, info, p, PIDTYPE_TGID);
1288 : }
1289 :
1290 0 : int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1291 : enum pid_type type)
1292 : {
1293 : unsigned long flags;
1294 0 : int ret = -ESRCH;
1295 :
1296 0 : if (lock_task_sighand(p, &flags)) {
1297 0 : ret = send_signal(sig, info, p, type);
1298 0 : unlock_task_sighand(p, &flags);
1299 : }
1300 :
1301 0 : return ret;
1302 : }
1303 :
1304 : enum sig_handler {
1305 : HANDLER_CURRENT, /* If reachable use the current handler */
1306 : HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1307 : HANDLER_EXIT, /* Only visible as the process exit code */
1308 : };
1309 :
1310 : /*
1311 : * Force a signal that the process can't ignore: if necessary
1312 : * we unblock the signal and change any SIG_IGN to SIG_DFL.
1313 : *
1314 : * Note: If we unblock the signal, we always reset it to SIG_DFL,
1315 : * since we do not want to have a signal handler that was blocked
1316 : * be invoked when user space had explicitly blocked it.
1317 : *
1318 : * We don't want to have recursive SIGSEGV's etc, for example,
1319 : * that is why we also clear SIGNAL_UNKILLABLE.
1320 : */
1321 : static int
1322 0 : force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1323 : enum sig_handler handler)
1324 : {
1325 : unsigned long int flags;
1326 : int ret, blocked, ignored;
1327 : struct k_sigaction *action;
1328 0 : int sig = info->si_signo;
1329 :
1330 0 : spin_lock_irqsave(&t->sighand->siglock, flags);
1331 0 : action = &t->sighand->action[sig-1];
1332 0 : ignored = action->sa.sa_handler == SIG_IGN;
1333 0 : blocked = sigismember(&t->blocked, sig);
1334 0 : if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1335 0 : action->sa.sa_handler = SIG_DFL;
1336 0 : if (handler == HANDLER_EXIT)
1337 0 : action->sa.sa_flags |= SA_IMMUTABLE;
1338 0 : if (blocked) {
1339 0 : sigdelset(&t->blocked, sig);
1340 0 : recalc_sigpending_and_wake(t);
1341 : }
1342 : }
1343 : /*
1344 : * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1345 : * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1346 : */
1347 0 : if (action->sa.sa_handler == SIG_DFL &&
1348 0 : (!t->ptrace || (handler == HANDLER_EXIT)))
1349 0 : t->signal->flags &= ~SIGNAL_UNKILLABLE;
1350 0 : ret = send_signal(sig, info, t, PIDTYPE_PID);
1351 0 : spin_unlock_irqrestore(&t->sighand->siglock, flags);
1352 :
1353 0 : return ret;
1354 : }
1355 :
1356 0 : int force_sig_info(struct kernel_siginfo *info)
1357 : {
1358 0 : return force_sig_info_to_task(info, current, HANDLER_CURRENT);
1359 : }
1360 :
1361 : /*
1362 : * Nuke all other threads in the group.
1363 : */
1364 0 : int zap_other_threads(struct task_struct *p)
1365 : {
1366 0 : struct task_struct *t = p;
1367 0 : int count = 0;
1368 :
1369 0 : p->signal->group_stop_count = 0;
1370 :
1371 0 : while_each_thread(p, t) {
1372 0 : task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1373 0 : count++;
1374 :
1375 : /* Don't bother with already dead threads */
1376 0 : if (t->exit_state)
1377 0 : continue;
1378 0 : sigaddset(&t->pending.signal, SIGKILL);
1379 : signal_wake_up(t, 1);
1380 : }
1381 :
1382 0 : return count;
1383 : }
1384 :
1385 0 : struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1386 : unsigned long *flags)
1387 : {
1388 : struct sighand_struct *sighand;
1389 :
1390 : rcu_read_lock();
1391 : for (;;) {
1392 0 : sighand = rcu_dereference(tsk->sighand);
1393 0 : if (unlikely(sighand == NULL))
1394 : break;
1395 :
1396 : /*
1397 : * This sighand can be already freed and even reused, but
1398 : * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1399 : * initializes ->siglock: this slab can't go away, it has
1400 : * the same object type, ->siglock can't be reinitialized.
1401 : *
1402 : * We need to ensure that tsk->sighand is still the same
1403 : * after we take the lock, we can race with de_thread() or
1404 : * __exit_signal(). In the latter case the next iteration
1405 : * must see ->sighand == NULL.
1406 : */
1407 0 : spin_lock_irqsave(&sighand->siglock, *flags);
1408 0 : if (likely(sighand == rcu_access_pointer(tsk->sighand)))
1409 : break;
1410 0 : spin_unlock_irqrestore(&sighand->siglock, *flags);
1411 : }
1412 : rcu_read_unlock();
1413 :
1414 0 : return sighand;
1415 : }
1416 :
1417 : #ifdef CONFIG_LOCKDEP
1418 : void lockdep_assert_task_sighand_held(struct task_struct *task)
1419 : {
1420 : struct sighand_struct *sighand;
1421 :
1422 : rcu_read_lock();
1423 : sighand = rcu_dereference(task->sighand);
1424 : if (sighand)
1425 : lockdep_assert_held(&sighand->siglock);
1426 : else
1427 : WARN_ON_ONCE(1);
1428 : rcu_read_unlock();
1429 : }
1430 : #endif
1431 :
1432 : /*
1433 : * send signal info to all the members of a group
1434 : */
1435 0 : int group_send_sig_info(int sig, struct kernel_siginfo *info,
1436 : struct task_struct *p, enum pid_type type)
1437 : {
1438 : int ret;
1439 :
1440 : rcu_read_lock();
1441 0 : ret = check_kill_permission(sig, info, p);
1442 : rcu_read_unlock();
1443 :
1444 0 : if (!ret && sig)
1445 0 : ret = do_send_sig_info(sig, info, p, type);
1446 :
1447 0 : return ret;
1448 : }
1449 :
1450 : /*
1451 : * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1452 : * control characters do (^C, ^Z etc)
1453 : * - the caller must hold at least a readlock on tasklist_lock
1454 : */
1455 0 : int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1456 : {
1457 0 : struct task_struct *p = NULL;
1458 : int retval, success;
1459 :
1460 0 : success = 0;
1461 0 : retval = -ESRCH;
1462 0 : do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1463 0 : int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1464 0 : success |= !err;
1465 0 : retval = err;
1466 : } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1467 0 : return success ? 0 : retval;
1468 : }
1469 :
1470 0 : int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1471 : {
1472 0 : int error = -ESRCH;
1473 : struct task_struct *p;
1474 :
1475 : for (;;) {
1476 : rcu_read_lock();
1477 0 : p = pid_task(pid, PIDTYPE_PID);
1478 0 : if (p)
1479 0 : error = group_send_sig_info(sig, info, p, PIDTYPE_TGID);
1480 : rcu_read_unlock();
1481 0 : if (likely(!p || error != -ESRCH))
1482 0 : return error;
1483 :
1484 : /*
1485 : * The task was unhashed in between, try again. If it
1486 : * is dead, pid_task() will return NULL, if we race with
1487 : * de_thread() it will find the new leader.
1488 : */
1489 : }
1490 : }
1491 :
1492 : static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1493 : {
1494 : int error;
1495 : rcu_read_lock();
1496 0 : error = kill_pid_info(sig, info, find_vpid(pid));
1497 : rcu_read_unlock();
1498 : return error;
1499 : }
1500 :
1501 : static inline bool kill_as_cred_perm(const struct cred *cred,
1502 : struct task_struct *target)
1503 : {
1504 0 : const struct cred *pcred = __task_cred(target);
1505 :
1506 0 : return uid_eq(cred->euid, pcred->suid) ||
1507 0 : uid_eq(cred->euid, pcred->uid) ||
1508 0 : uid_eq(cred->uid, pcred->suid) ||
1509 0 : uid_eq(cred->uid, pcred->uid);
1510 : }
1511 :
1512 : /*
1513 : * The usb asyncio usage of siginfo is wrong. The glibc support
1514 : * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1515 : * AKA after the generic fields:
1516 : * kernel_pid_t si_pid;
1517 : * kernel_uid32_t si_uid;
1518 : * sigval_t si_value;
1519 : *
1520 : * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1521 : * after the generic fields is:
1522 : * void __user *si_addr;
1523 : *
1524 : * This is a practical problem when there is a 64bit big endian kernel
1525 : * and a 32bit userspace. As the 32bit address will encoded in the low
1526 : * 32bits of the pointer. Those low 32bits will be stored at higher
1527 : * address than appear in a 32 bit pointer. So userspace will not
1528 : * see the address it was expecting for it's completions.
1529 : *
1530 : * There is nothing in the encoding that can allow
1531 : * copy_siginfo_to_user32 to detect this confusion of formats, so
1532 : * handle this by requiring the caller of kill_pid_usb_asyncio to
1533 : * notice when this situration takes place and to store the 32bit
1534 : * pointer in sival_int, instead of sival_addr of the sigval_t addr
1535 : * parameter.
1536 : */
1537 0 : int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1538 : struct pid *pid, const struct cred *cred)
1539 : {
1540 : struct kernel_siginfo info;
1541 : struct task_struct *p;
1542 : unsigned long flags;
1543 0 : int ret = -EINVAL;
1544 :
1545 0 : if (!valid_signal(sig))
1546 : return ret;
1547 :
1548 0 : clear_siginfo(&info);
1549 0 : info.si_signo = sig;
1550 0 : info.si_errno = errno;
1551 0 : info.si_code = SI_ASYNCIO;
1552 0 : *((sigval_t *)&info.si_pid) = addr;
1553 :
1554 : rcu_read_lock();
1555 0 : p = pid_task(pid, PIDTYPE_PID);
1556 0 : if (!p) {
1557 : ret = -ESRCH;
1558 : goto out_unlock;
1559 : }
1560 0 : if (!kill_as_cred_perm(cred, p)) {
1561 : ret = -EPERM;
1562 : goto out_unlock;
1563 : }
1564 0 : ret = security_task_kill(p, &info, sig, cred);
1565 : if (ret)
1566 : goto out_unlock;
1567 :
1568 0 : if (sig) {
1569 0 : if (lock_task_sighand(p, &flags)) {
1570 0 : ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
1571 0 : unlock_task_sighand(p, &flags);
1572 : } else
1573 : ret = -ESRCH;
1574 : }
1575 : out_unlock:
1576 : rcu_read_unlock();
1577 0 : return ret;
1578 : }
1579 : EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1580 :
1581 : /*
1582 : * kill_something_info() interprets pid in interesting ways just like kill(2).
1583 : *
1584 : * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1585 : * is probably wrong. Should make it like BSD or SYSV.
1586 : */
1587 :
1588 0 : static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1589 : {
1590 : int ret;
1591 :
1592 0 : if (pid > 0)
1593 0 : return kill_proc_info(sig, info, pid);
1594 :
1595 : /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */
1596 0 : if (pid == INT_MIN)
1597 : return -ESRCH;
1598 :
1599 0 : read_lock(&tasklist_lock);
1600 0 : if (pid != -1) {
1601 0 : ret = __kill_pgrp_info(sig, info,
1602 0 : pid ? find_vpid(-pid) : task_pgrp(current));
1603 : } else {
1604 : int retval = 0, count = 0;
1605 : struct task_struct * p;
1606 :
1607 0 : for_each_process(p) {
1608 0 : if (task_pid_vnr(p) > 1 &&
1609 0 : !same_thread_group(p, current)) {
1610 0 : int err = group_send_sig_info(sig, info, p,
1611 : PIDTYPE_MAX);
1612 0 : ++count;
1613 0 : if (err != -EPERM)
1614 0 : retval = err;
1615 : }
1616 : }
1617 0 : ret = count ? retval : -ESRCH;
1618 : }
1619 0 : read_unlock(&tasklist_lock);
1620 :
1621 0 : return ret;
1622 : }
1623 :
1624 : /*
1625 : * These are for backward compatibility with the rest of the kernel source.
1626 : */
1627 :
1628 0 : int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1629 : {
1630 : /*
1631 : * Make sure legacy kernel users don't send in bad values
1632 : * (normal paths check this in check_kill_permission).
1633 : */
1634 0 : if (!valid_signal(sig))
1635 : return -EINVAL;
1636 :
1637 0 : return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1638 : }
1639 : EXPORT_SYMBOL(send_sig_info);
1640 :
1641 : #define __si_special(priv) \
1642 : ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1643 :
1644 : int
1645 0 : send_sig(int sig, struct task_struct *p, int priv)
1646 : {
1647 0 : return send_sig_info(sig, __si_special(priv), p);
1648 : }
1649 : EXPORT_SYMBOL(send_sig);
1650 :
1651 0 : void force_sig(int sig)
1652 : {
1653 : struct kernel_siginfo info;
1654 :
1655 0 : clear_siginfo(&info);
1656 0 : info.si_signo = sig;
1657 0 : info.si_errno = 0;
1658 0 : info.si_code = SI_KERNEL;
1659 0 : info.si_pid = 0;
1660 0 : info.si_uid = 0;
1661 0 : force_sig_info(&info);
1662 0 : }
1663 : EXPORT_SYMBOL(force_sig);
1664 :
1665 0 : void force_fatal_sig(int sig)
1666 : {
1667 : struct kernel_siginfo info;
1668 :
1669 0 : clear_siginfo(&info);
1670 0 : info.si_signo = sig;
1671 0 : info.si_errno = 0;
1672 0 : info.si_code = SI_KERNEL;
1673 0 : info.si_pid = 0;
1674 0 : info.si_uid = 0;
1675 0 : force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
1676 0 : }
1677 :
1678 0 : void force_exit_sig(int sig)
1679 : {
1680 : struct kernel_siginfo info;
1681 :
1682 0 : clear_siginfo(&info);
1683 0 : info.si_signo = sig;
1684 0 : info.si_errno = 0;
1685 0 : info.si_code = SI_KERNEL;
1686 0 : info.si_pid = 0;
1687 0 : info.si_uid = 0;
1688 0 : force_sig_info_to_task(&info, current, HANDLER_EXIT);
1689 0 : }
1690 :
1691 : /*
1692 : * When things go south during signal handling, we
1693 : * will force a SIGSEGV. And if the signal that caused
1694 : * the problem was already a SIGSEGV, we'll want to
1695 : * make sure we don't even try to deliver the signal..
1696 : */
1697 0 : void force_sigsegv(int sig)
1698 : {
1699 0 : if (sig == SIGSEGV)
1700 0 : force_fatal_sig(SIGSEGV);
1701 : else
1702 0 : force_sig(SIGSEGV);
1703 0 : }
1704 :
1705 0 : int force_sig_fault_to_task(int sig, int code, void __user *addr
1706 : ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1707 : , struct task_struct *t)
1708 : {
1709 : struct kernel_siginfo info;
1710 :
1711 0 : clear_siginfo(&info);
1712 0 : info.si_signo = sig;
1713 0 : info.si_errno = 0;
1714 0 : info.si_code = code;
1715 0 : info.si_addr = addr;
1716 : #ifdef __ia64__
1717 : info.si_imm = imm;
1718 : info.si_flags = flags;
1719 : info.si_isr = isr;
1720 : #endif
1721 0 : return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
1722 : }
1723 :
1724 0 : int force_sig_fault(int sig, int code, void __user *addr
1725 : ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
1726 : {
1727 0 : return force_sig_fault_to_task(sig, code, addr
1728 0 : ___ARCH_SI_IA64(imm, flags, isr), current);
1729 : }
1730 :
1731 0 : int send_sig_fault(int sig, int code, void __user *addr
1732 : ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1733 : , struct task_struct *t)
1734 : {
1735 : struct kernel_siginfo info;
1736 :
1737 0 : clear_siginfo(&info);
1738 0 : info.si_signo = sig;
1739 0 : info.si_errno = 0;
1740 0 : info.si_code = code;
1741 0 : info.si_addr = addr;
1742 : #ifdef __ia64__
1743 : info.si_imm = imm;
1744 : info.si_flags = flags;
1745 : info.si_isr = isr;
1746 : #endif
1747 0 : return send_sig_info(info.si_signo, &info, t);
1748 : }
1749 :
1750 0 : int force_sig_mceerr(int code, void __user *addr, short lsb)
1751 : {
1752 : struct kernel_siginfo info;
1753 :
1754 0 : WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1755 0 : clear_siginfo(&info);
1756 0 : info.si_signo = SIGBUS;
1757 0 : info.si_errno = 0;
1758 0 : info.si_code = code;
1759 0 : info.si_addr = addr;
1760 0 : info.si_addr_lsb = lsb;
1761 0 : return force_sig_info(&info);
1762 : }
1763 :
1764 0 : int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1765 : {
1766 : struct kernel_siginfo info;
1767 :
1768 0 : WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1769 0 : clear_siginfo(&info);
1770 0 : info.si_signo = SIGBUS;
1771 0 : info.si_errno = 0;
1772 0 : info.si_code = code;
1773 0 : info.si_addr = addr;
1774 0 : info.si_addr_lsb = lsb;
1775 0 : return send_sig_info(info.si_signo, &info, t);
1776 : }
1777 : EXPORT_SYMBOL(send_sig_mceerr);
1778 :
1779 0 : int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1780 : {
1781 : struct kernel_siginfo info;
1782 :
1783 0 : clear_siginfo(&info);
1784 0 : info.si_signo = SIGSEGV;
1785 0 : info.si_errno = 0;
1786 0 : info.si_code = SEGV_BNDERR;
1787 0 : info.si_addr = addr;
1788 0 : info.si_lower = lower;
1789 0 : info.si_upper = upper;
1790 0 : return force_sig_info(&info);
1791 : }
1792 :
1793 : #ifdef SEGV_PKUERR
1794 0 : int force_sig_pkuerr(void __user *addr, u32 pkey)
1795 : {
1796 : struct kernel_siginfo info;
1797 :
1798 0 : clear_siginfo(&info);
1799 0 : info.si_signo = SIGSEGV;
1800 0 : info.si_errno = 0;
1801 0 : info.si_code = SEGV_PKUERR;
1802 0 : info.si_addr = addr;
1803 0 : info.si_pkey = pkey;
1804 0 : return force_sig_info(&info);
1805 : }
1806 : #endif
1807 :
1808 0 : int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
1809 : {
1810 : struct kernel_siginfo info;
1811 :
1812 0 : clear_siginfo(&info);
1813 0 : info.si_signo = SIGTRAP;
1814 0 : info.si_errno = 0;
1815 0 : info.si_code = TRAP_PERF;
1816 0 : info.si_addr = addr;
1817 0 : info.si_perf_data = sig_data;
1818 0 : info.si_perf_type = type;
1819 :
1820 0 : return force_sig_info(&info);
1821 : }
1822 :
1823 : /**
1824 : * force_sig_seccomp - signals the task to allow in-process syscall emulation
1825 : * @syscall: syscall number to send to userland
1826 : * @reason: filter-supplied reason code to send to userland (via si_errno)
1827 : * @force_coredump: true to trigger a coredump
1828 : *
1829 : * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1830 : */
1831 0 : int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1832 : {
1833 : struct kernel_siginfo info;
1834 :
1835 0 : clear_siginfo(&info);
1836 0 : info.si_signo = SIGSYS;
1837 0 : info.si_code = SYS_SECCOMP;
1838 0 : info.si_call_addr = (void __user *)KSTK_EIP(current);
1839 0 : info.si_errno = reason;
1840 0 : info.si_arch = syscall_get_arch(current);
1841 0 : info.si_syscall = syscall;
1842 0 : return force_sig_info_to_task(&info, current,
1843 : force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1844 : }
1845 :
1846 : /* For the crazy architectures that include trap information in
1847 : * the errno field, instead of an actual errno value.
1848 : */
1849 0 : int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1850 : {
1851 : struct kernel_siginfo info;
1852 :
1853 0 : clear_siginfo(&info);
1854 0 : info.si_signo = SIGTRAP;
1855 0 : info.si_errno = errno;
1856 0 : info.si_code = TRAP_HWBKPT;
1857 0 : info.si_addr = addr;
1858 0 : return force_sig_info(&info);
1859 : }
1860 :
1861 : /* For the rare architectures that include trap information using
1862 : * si_trapno.
1863 : */
1864 0 : int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1865 : {
1866 : struct kernel_siginfo info;
1867 :
1868 0 : clear_siginfo(&info);
1869 0 : info.si_signo = sig;
1870 0 : info.si_errno = 0;
1871 0 : info.si_code = code;
1872 0 : info.si_addr = addr;
1873 0 : info.si_trapno = trapno;
1874 0 : return force_sig_info(&info);
1875 : }
1876 :
1877 : /* For the rare architectures that include trap information using
1878 : * si_trapno.
1879 : */
1880 0 : int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1881 : struct task_struct *t)
1882 : {
1883 : struct kernel_siginfo info;
1884 :
1885 0 : clear_siginfo(&info);
1886 0 : info.si_signo = sig;
1887 0 : info.si_errno = 0;
1888 0 : info.si_code = code;
1889 0 : info.si_addr = addr;
1890 0 : info.si_trapno = trapno;
1891 0 : return send_sig_info(info.si_signo, &info, t);
1892 : }
1893 :
1894 0 : int kill_pgrp(struct pid *pid, int sig, int priv)
1895 : {
1896 : int ret;
1897 :
1898 0 : read_lock(&tasklist_lock);
1899 0 : ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1900 0 : read_unlock(&tasklist_lock);
1901 :
1902 0 : return ret;
1903 : }
1904 : EXPORT_SYMBOL(kill_pgrp);
1905 :
1906 0 : int kill_pid(struct pid *pid, int sig, int priv)
1907 : {
1908 0 : return kill_pid_info(sig, __si_special(priv), pid);
1909 : }
1910 : EXPORT_SYMBOL(kill_pid);
1911 :
1912 : /*
1913 : * These functions support sending signals using preallocated sigqueue
1914 : * structures. This is needed "because realtime applications cannot
1915 : * afford to lose notifications of asynchronous events, like timer
1916 : * expirations or I/O completions". In the case of POSIX Timers
1917 : * we allocate the sigqueue structure from the timer_create. If this
1918 : * allocation fails we are able to report the failure to the application
1919 : * with an EAGAIN error.
1920 : */
1921 0 : struct sigqueue *sigqueue_alloc(void)
1922 : {
1923 0 : return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
1924 : }
1925 :
1926 0 : void sigqueue_free(struct sigqueue *q)
1927 : {
1928 : unsigned long flags;
1929 0 : spinlock_t *lock = ¤t->sighand->siglock;
1930 :
1931 0 : BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1932 : /*
1933 : * We must hold ->siglock while testing q->list
1934 : * to serialize with collect_signal() or with
1935 : * __exit_signal()->flush_sigqueue().
1936 : */
1937 0 : spin_lock_irqsave(lock, flags);
1938 0 : q->flags &= ~SIGQUEUE_PREALLOC;
1939 : /*
1940 : * If it is queued it will be freed when dequeued,
1941 : * like the "regular" sigqueue.
1942 : */
1943 0 : if (!list_empty(&q->list))
1944 0 : q = NULL;
1945 0 : spin_unlock_irqrestore(lock, flags);
1946 :
1947 0 : if (q)
1948 0 : __sigqueue_free(q);
1949 0 : }
1950 :
1951 0 : int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1952 : {
1953 0 : int sig = q->info.si_signo;
1954 : struct sigpending *pending;
1955 : struct task_struct *t;
1956 : unsigned long flags;
1957 : int ret, result;
1958 :
1959 0 : BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1960 :
1961 0 : ret = -1;
1962 : rcu_read_lock();
1963 0 : t = pid_task(pid, type);
1964 0 : if (!t || !likely(lock_task_sighand(t, &flags)))
1965 : goto ret;
1966 :
1967 0 : ret = 1; /* the signal is ignored */
1968 0 : result = TRACE_SIGNAL_IGNORED;
1969 0 : if (!prepare_signal(sig, t, false))
1970 : goto out;
1971 :
1972 0 : ret = 0;
1973 0 : if (unlikely(!list_empty(&q->list))) {
1974 : /*
1975 : * If an SI_TIMER entry is already queue just increment
1976 : * the overrun count.
1977 : */
1978 0 : BUG_ON(q->info.si_code != SI_TIMER);
1979 0 : q->info.si_overrun++;
1980 0 : result = TRACE_SIGNAL_ALREADY_PENDING;
1981 0 : goto out;
1982 : }
1983 0 : q->info.si_overrun = 0;
1984 :
1985 0 : signalfd_notify(t, sig);
1986 0 : pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1987 0 : list_add_tail(&q->list, &pending->list);
1988 0 : sigaddset(&pending->signal, sig);
1989 0 : complete_signal(sig, t, type);
1990 0 : result = TRACE_SIGNAL_DELIVERED;
1991 : out:
1992 0 : trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
1993 0 : unlock_task_sighand(t, &flags);
1994 : ret:
1995 : rcu_read_unlock();
1996 0 : return ret;
1997 : }
1998 :
1999 93 : static void do_notify_pidfd(struct task_struct *task)
2000 : {
2001 : struct pid *pid;
2002 :
2003 93 : WARN_ON(task->exit_state == 0);
2004 93 : pid = task_pid(task);
2005 93 : wake_up_all(&pid->wait_pidfd);
2006 93 : }
2007 :
2008 : /*
2009 : * Let a parent know about the death of a child.
2010 : * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2011 : *
2012 : * Returns true if our parent ignored us and so we've switched to
2013 : * self-reaping.
2014 : */
2015 93 : bool do_notify_parent(struct task_struct *tsk, int sig)
2016 : {
2017 : struct kernel_siginfo info;
2018 : unsigned long flags;
2019 : struct sighand_struct *psig;
2020 93 : bool autoreap = false;
2021 : u64 utime, stime;
2022 :
2023 93 : BUG_ON(sig == -1);
2024 :
2025 : /* do_notify_parent_cldstop should have been called instead. */
2026 93 : BUG_ON(task_is_stopped_or_traced(tsk));
2027 :
2028 186 : BUG_ON(!tsk->ptrace &&
2029 : (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2030 :
2031 : /* Wake up all pidfd waiters */
2032 93 : do_notify_pidfd(tsk);
2033 :
2034 93 : if (sig != SIGCHLD) {
2035 : /*
2036 : * This is only possible if parent == real_parent.
2037 : * Check if it has changed security domain.
2038 : */
2039 0 : if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2040 0 : sig = SIGCHLD;
2041 : }
2042 :
2043 93 : clear_siginfo(&info);
2044 93 : info.si_signo = sig;
2045 93 : info.si_errno = 0;
2046 : /*
2047 : * We are under tasklist_lock here so our parent is tied to
2048 : * us and cannot change.
2049 : *
2050 : * task_active_pid_ns will always return the same pid namespace
2051 : * until a task passes through release_task.
2052 : *
2053 : * write_lock() currently calls preempt_disable() which is the
2054 : * same as rcu_read_lock(), but according to Oleg, this is not
2055 : * correct to rely on this
2056 : */
2057 : rcu_read_lock();
2058 186 : info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2059 279 : info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2060 93 : task_uid(tsk));
2061 : rcu_read_unlock();
2062 :
2063 186 : task_cputime(tsk, &utime, &stime);
2064 93 : info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2065 93 : info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2066 :
2067 93 : info.si_status = tsk->exit_code & 0x7f;
2068 93 : if (tsk->exit_code & 0x80)
2069 0 : info.si_code = CLD_DUMPED;
2070 93 : else if (tsk->exit_code & 0x7f)
2071 0 : info.si_code = CLD_KILLED;
2072 : else {
2073 93 : info.si_code = CLD_EXITED;
2074 93 : info.si_status = tsk->exit_code >> 8;
2075 : }
2076 :
2077 93 : psig = tsk->parent->sighand;
2078 93 : spin_lock_irqsave(&psig->siglock, flags);
2079 186 : if (!tsk->ptrace && sig == SIGCHLD &&
2080 93 : (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2081 0 : (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2082 : /*
2083 : * We are exiting and our parent doesn't care. POSIX.1
2084 : * defines special semantics for setting SIGCHLD to SIG_IGN
2085 : * or setting the SA_NOCLDWAIT flag: we should be reaped
2086 : * automatically and not left for our parent's wait4 call.
2087 : * Rather than having the parent do it as a magic kind of
2088 : * signal handler, we just set this to tell do_exit that we
2089 : * can be cleaned up without becoming a zombie. Note that
2090 : * we still call __wake_up_parent in this case, because a
2091 : * blocked sys_wait4 might now return -ECHILD.
2092 : *
2093 : * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2094 : * is implementation-defined: we do (if you don't want
2095 : * it, just use SIG_IGN instead).
2096 : */
2097 93 : autoreap = true;
2098 93 : if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2099 93 : sig = 0;
2100 : }
2101 : /*
2102 : * Send with __send_signal as si_pid and si_uid are in the
2103 : * parent's namespaces.
2104 : */
2105 93 : if (valid_signal(sig) && sig)
2106 0 : __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2107 93 : __wake_up_parent(tsk, tsk->parent);
2108 186 : spin_unlock_irqrestore(&psig->siglock, flags);
2109 :
2110 93 : return autoreap;
2111 : }
2112 :
2113 : /**
2114 : * do_notify_parent_cldstop - notify parent of stopped/continued state change
2115 : * @tsk: task reporting the state change
2116 : * @for_ptracer: the notification is for ptracer
2117 : * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2118 : *
2119 : * Notify @tsk's parent that the stopped/continued state has changed. If
2120 : * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2121 : * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2122 : *
2123 : * CONTEXT:
2124 : * Must be called with tasklist_lock at least read locked.
2125 : */
2126 0 : static void do_notify_parent_cldstop(struct task_struct *tsk,
2127 : bool for_ptracer, int why)
2128 : {
2129 : struct kernel_siginfo info;
2130 : unsigned long flags;
2131 : struct task_struct *parent;
2132 : struct sighand_struct *sighand;
2133 : u64 utime, stime;
2134 :
2135 0 : if (for_ptracer) {
2136 0 : parent = tsk->parent;
2137 : } else {
2138 0 : tsk = tsk->group_leader;
2139 0 : parent = tsk->real_parent;
2140 : }
2141 :
2142 0 : clear_siginfo(&info);
2143 0 : info.si_signo = SIGCHLD;
2144 0 : info.si_errno = 0;
2145 : /*
2146 : * see comment in do_notify_parent() about the following 4 lines
2147 : */
2148 : rcu_read_lock();
2149 0 : info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2150 0 : info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2151 : rcu_read_unlock();
2152 :
2153 0 : task_cputime(tsk, &utime, &stime);
2154 0 : info.si_utime = nsec_to_clock_t(utime);
2155 0 : info.si_stime = nsec_to_clock_t(stime);
2156 :
2157 0 : info.si_code = why;
2158 0 : switch (why) {
2159 : case CLD_CONTINUED:
2160 0 : info.si_status = SIGCONT;
2161 0 : break;
2162 : case CLD_STOPPED:
2163 0 : info.si_status = tsk->signal->group_exit_code & 0x7f;
2164 0 : break;
2165 : case CLD_TRAPPED:
2166 0 : info.si_status = tsk->exit_code & 0x7f;
2167 0 : break;
2168 : default:
2169 0 : BUG();
2170 : }
2171 :
2172 0 : sighand = parent->sighand;
2173 0 : spin_lock_irqsave(&sighand->siglock, flags);
2174 0 : if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2175 0 : !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2176 : __group_send_sig_info(SIGCHLD, &info, parent);
2177 : /*
2178 : * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2179 : */
2180 0 : __wake_up_parent(tsk, parent);
2181 0 : spin_unlock_irqrestore(&sighand->siglock, flags);
2182 0 : }
2183 :
2184 : /*
2185 : * This must be called with current->sighand->siglock held.
2186 : *
2187 : * This should be the path for all ptrace stops.
2188 : * We always set current->last_siginfo while stopped here.
2189 : * That makes it a way to test a stopped process for
2190 : * being ptrace-stopped vs being job-control-stopped.
2191 : *
2192 : * Returns the signal the ptracer requested the code resume
2193 : * with. If the code did not stop because the tracer is gone,
2194 : * the stop signal remains unchanged unless clear_code.
2195 : */
2196 0 : static int ptrace_stop(int exit_code, int why, int clear_code,
2197 : unsigned long message, kernel_siginfo_t *info)
2198 : __releases(¤t->sighand->siglock)
2199 : __acquires(¤t->sighand->siglock)
2200 : {
2201 0 : bool gstop_done = false;
2202 0 : bool read_code = true;
2203 :
2204 : if (arch_ptrace_stop_needed()) {
2205 : /*
2206 : * The arch code has something special to do before a
2207 : * ptrace stop. This is allowed to block, e.g. for faults
2208 : * on user stack pages. We can't keep the siglock while
2209 : * calling arch_ptrace_stop, so we must release it now.
2210 : * To preserve proper semantics, we must do this before
2211 : * any signal bookkeeping like checking group_stop_count.
2212 : */
2213 : spin_unlock_irq(¤t->sighand->siglock);
2214 : arch_ptrace_stop();
2215 : spin_lock_irq(¤t->sighand->siglock);
2216 : }
2217 :
2218 : /*
2219 : * schedule() will not sleep if there is a pending signal that
2220 : * can awaken the task.
2221 : */
2222 0 : set_special_state(TASK_TRACED);
2223 :
2224 : /*
2225 : * We're committing to trapping. TRACED should be visible before
2226 : * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2227 : * Also, transition to TRACED and updates to ->jobctl should be
2228 : * atomic with respect to siglock and should be done after the arch
2229 : * hook as siglock is released and regrabbed across it.
2230 : *
2231 : * TRACER TRACEE
2232 : *
2233 : * ptrace_attach()
2234 : * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED)
2235 : * do_wait()
2236 : * set_current_state() smp_wmb();
2237 : * ptrace_do_wait()
2238 : * wait_task_stopped()
2239 : * task_stopped_code()
2240 : * [L] task_is_traced() [S] task_clear_jobctl_trapping();
2241 : */
2242 0 : smp_wmb();
2243 :
2244 0 : current->ptrace_message = message;
2245 0 : current->last_siginfo = info;
2246 0 : current->exit_code = exit_code;
2247 :
2248 : /*
2249 : * If @why is CLD_STOPPED, we're trapping to participate in a group
2250 : * stop. Do the bookkeeping. Note that if SIGCONT was delievered
2251 : * across siglock relocks since INTERRUPT was scheduled, PENDING
2252 : * could be clear now. We act as if SIGCONT is received after
2253 : * TASK_TRACED is entered - ignore it.
2254 : */
2255 0 : if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2256 0 : gstop_done = task_participate_group_stop(current);
2257 :
2258 : /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2259 0 : task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2260 0 : if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2261 0 : task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2262 :
2263 : /* entering a trap, clear TRAPPING */
2264 0 : task_clear_jobctl_trapping(current);
2265 :
2266 0 : spin_unlock_irq(¤t->sighand->siglock);
2267 0 : read_lock(&tasklist_lock);
2268 0 : if (likely(current->ptrace)) {
2269 : /*
2270 : * Notify parents of the stop.
2271 : *
2272 : * While ptraced, there are two parents - the ptracer and
2273 : * the real_parent of the group_leader. The ptracer should
2274 : * know about every stop while the real parent is only
2275 : * interested in the completion of group stop. The states
2276 : * for the two don't interact with each other. Notify
2277 : * separately unless they're gonna be duplicates.
2278 : */
2279 0 : do_notify_parent_cldstop(current, true, why);
2280 0 : if (gstop_done && ptrace_reparented(current))
2281 0 : do_notify_parent_cldstop(current, false, why);
2282 :
2283 : /*
2284 : * Don't want to allow preemption here, because
2285 : * sys_ptrace() needs this task to be inactive.
2286 : *
2287 : * XXX: implement read_unlock_no_resched().
2288 : */
2289 0 : preempt_disable();
2290 0 : read_unlock(&tasklist_lock);
2291 : cgroup_enter_frozen();
2292 0 : preempt_enable_no_resched();
2293 0 : freezable_schedule();
2294 : cgroup_leave_frozen(true);
2295 : } else {
2296 : /*
2297 : * By the time we got the lock, our tracer went away.
2298 : * Don't drop the lock yet, another tracer may come.
2299 : *
2300 : * If @gstop_done, the ptracer went away between group stop
2301 : * completion and here. During detach, it would have set
2302 : * JOBCTL_STOP_PENDING on us and we'll re-enter
2303 : * TASK_STOPPED in do_signal_stop() on return, so notifying
2304 : * the real parent of the group stop completion is enough.
2305 : */
2306 0 : if (gstop_done)
2307 0 : do_notify_parent_cldstop(current, false, why);
2308 :
2309 : /* tasklist protects us from ptrace_freeze_traced() */
2310 0 : __set_current_state(TASK_RUNNING);
2311 0 : read_code = false;
2312 0 : if (clear_code)
2313 0 : exit_code = 0;
2314 0 : read_unlock(&tasklist_lock);
2315 : }
2316 :
2317 : /*
2318 : * We are back. Now reacquire the siglock before touching
2319 : * last_siginfo, so that we are sure to have synchronized with
2320 : * any signal-sending on another CPU that wants to examine it.
2321 : */
2322 0 : spin_lock_irq(¤t->sighand->siglock);
2323 0 : if (read_code)
2324 0 : exit_code = current->exit_code;
2325 0 : current->last_siginfo = NULL;
2326 0 : current->ptrace_message = 0;
2327 0 : current->exit_code = 0;
2328 :
2329 : /* LISTENING can be set only during STOP traps, clear it */
2330 0 : current->jobctl &= ~JOBCTL_LISTENING;
2331 :
2332 : /*
2333 : * Queued signals ignored us while we were stopped for tracing.
2334 : * So check for any that we should take before resuming user mode.
2335 : * This sets TIF_SIGPENDING, but never clears it.
2336 : */
2337 0 : recalc_sigpending_tsk(current);
2338 0 : return exit_code;
2339 : }
2340 :
2341 0 : static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2342 : {
2343 : kernel_siginfo_t info;
2344 :
2345 0 : clear_siginfo(&info);
2346 0 : info.si_signo = signr;
2347 0 : info.si_code = exit_code;
2348 0 : info.si_pid = task_pid_vnr(current);
2349 0 : info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2350 :
2351 : /* Let the debugger run. */
2352 0 : return ptrace_stop(exit_code, why, 1, message, &info);
2353 : }
2354 :
2355 0 : int ptrace_notify(int exit_code, unsigned long message)
2356 : {
2357 : int signr;
2358 :
2359 0 : BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2360 0 : if (unlikely(task_work_pending(current)))
2361 0 : task_work_run();
2362 :
2363 0 : spin_lock_irq(¤t->sighand->siglock);
2364 0 : signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2365 0 : spin_unlock_irq(¤t->sighand->siglock);
2366 0 : return signr;
2367 : }
2368 :
2369 : /**
2370 : * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2371 : * @signr: signr causing group stop if initiating
2372 : *
2373 : * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2374 : * and participate in it. If already set, participate in the existing
2375 : * group stop. If participated in a group stop (and thus slept), %true is
2376 : * returned with siglock released.
2377 : *
2378 : * If ptraced, this function doesn't handle stop itself. Instead,
2379 : * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2380 : * untouched. The caller must ensure that INTERRUPT trap handling takes
2381 : * places afterwards.
2382 : *
2383 : * CONTEXT:
2384 : * Must be called with @current->sighand->siglock held, which is released
2385 : * on %true return.
2386 : *
2387 : * RETURNS:
2388 : * %false if group stop is already cancelled or ptrace trap is scheduled.
2389 : * %true if participated in group stop.
2390 : */
2391 0 : static bool do_signal_stop(int signr)
2392 : __releases(¤t->sighand->siglock)
2393 : {
2394 0 : struct signal_struct *sig = current->signal;
2395 :
2396 0 : if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2397 0 : unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2398 : struct task_struct *t;
2399 :
2400 : /* signr will be recorded in task->jobctl for retries */
2401 0 : WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2402 :
2403 0 : if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2404 0 : unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2405 0 : unlikely(sig->group_exec_task))
2406 : return false;
2407 : /*
2408 : * There is no group stop already in progress. We must
2409 : * initiate one now.
2410 : *
2411 : * While ptraced, a task may be resumed while group stop is
2412 : * still in effect and then receive a stop signal and
2413 : * initiate another group stop. This deviates from the
2414 : * usual behavior as two consecutive stop signals can't
2415 : * cause two group stops when !ptraced. That is why we
2416 : * also check !task_is_stopped(t) below.
2417 : *
2418 : * The condition can be distinguished by testing whether
2419 : * SIGNAL_STOP_STOPPED is already set. Don't generate
2420 : * group_exit_code in such case.
2421 : *
2422 : * This is not necessary for SIGNAL_STOP_CONTINUED because
2423 : * an intervening stop signal is required to cause two
2424 : * continued events regardless of ptrace.
2425 : */
2426 0 : if (!(sig->flags & SIGNAL_STOP_STOPPED))
2427 0 : sig->group_exit_code = signr;
2428 :
2429 0 : sig->group_stop_count = 0;
2430 :
2431 0 : if (task_set_jobctl_pending(current, signr | gstop))
2432 0 : sig->group_stop_count++;
2433 :
2434 0 : t = current;
2435 0 : while_each_thread(current, t) {
2436 : /*
2437 : * Setting state to TASK_STOPPED for a group
2438 : * stop is always done with the siglock held,
2439 : * so this check has no races.
2440 : */
2441 0 : if (!task_is_stopped(t) &&
2442 0 : task_set_jobctl_pending(t, signr | gstop)) {
2443 0 : sig->group_stop_count++;
2444 0 : if (likely(!(t->ptrace & PT_SEIZED)))
2445 : signal_wake_up(t, 0);
2446 : else
2447 0 : ptrace_trap_notify(t);
2448 : }
2449 : }
2450 : }
2451 :
2452 0 : if (likely(!current->ptrace)) {
2453 0 : int notify = 0;
2454 :
2455 : /*
2456 : * If there are no other threads in the group, or if there
2457 : * is a group stop in progress and we are the last to stop,
2458 : * report to the parent.
2459 : */
2460 0 : if (task_participate_group_stop(current))
2461 0 : notify = CLD_STOPPED;
2462 :
2463 0 : set_special_state(TASK_STOPPED);
2464 0 : spin_unlock_irq(¤t->sighand->siglock);
2465 :
2466 : /*
2467 : * Notify the parent of the group stop completion. Because
2468 : * we're not holding either the siglock or tasklist_lock
2469 : * here, ptracer may attach inbetween; however, this is for
2470 : * group stop and should always be delivered to the real
2471 : * parent of the group leader. The new ptracer will get
2472 : * its notification when this task transitions into
2473 : * TASK_TRACED.
2474 : */
2475 0 : if (notify) {
2476 0 : read_lock(&tasklist_lock);
2477 0 : do_notify_parent_cldstop(current, false, notify);
2478 0 : read_unlock(&tasklist_lock);
2479 : }
2480 :
2481 : /* Now we don't run again until woken by SIGCONT or SIGKILL */
2482 : cgroup_enter_frozen();
2483 0 : freezable_schedule();
2484 0 : return true;
2485 : } else {
2486 : /*
2487 : * While ptraced, group stop is handled by STOP trap.
2488 : * Schedule it and let the caller deal with it.
2489 : */
2490 0 : task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2491 0 : return false;
2492 : }
2493 : }
2494 :
2495 : /**
2496 : * do_jobctl_trap - take care of ptrace jobctl traps
2497 : *
2498 : * When PT_SEIZED, it's used for both group stop and explicit
2499 : * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
2500 : * accompanying siginfo. If stopped, lower eight bits of exit_code contain
2501 : * the stop signal; otherwise, %SIGTRAP.
2502 : *
2503 : * When !PT_SEIZED, it's used only for group stop trap with stop signal
2504 : * number as exit_code and no siginfo.
2505 : *
2506 : * CONTEXT:
2507 : * Must be called with @current->sighand->siglock held, which may be
2508 : * released and re-acquired before returning with intervening sleep.
2509 : */
2510 0 : static void do_jobctl_trap(void)
2511 : {
2512 0 : struct signal_struct *signal = current->signal;
2513 0 : int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2514 :
2515 0 : if (current->ptrace & PT_SEIZED) {
2516 0 : if (!signal->group_stop_count &&
2517 : !(signal->flags & SIGNAL_STOP_STOPPED))
2518 0 : signr = SIGTRAP;
2519 0 : WARN_ON_ONCE(!signr);
2520 0 : ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2521 : CLD_STOPPED, 0);
2522 : } else {
2523 0 : WARN_ON_ONCE(!signr);
2524 0 : ptrace_stop(signr, CLD_STOPPED, 0, 0, NULL);
2525 : }
2526 0 : }
2527 :
2528 : /**
2529 : * do_freezer_trap - handle the freezer jobctl trap
2530 : *
2531 : * Puts the task into frozen state, if only the task is not about to quit.
2532 : * In this case it drops JOBCTL_TRAP_FREEZE.
2533 : *
2534 : * CONTEXT:
2535 : * Must be called with @current->sighand->siglock held,
2536 : * which is always released before returning.
2537 : */
2538 0 : static void do_freezer_trap(void)
2539 : __releases(¤t->sighand->siglock)
2540 : {
2541 : /*
2542 : * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2543 : * let's make another loop to give it a chance to be handled.
2544 : * In any case, we'll return back.
2545 : */
2546 0 : if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2547 : JOBCTL_TRAP_FREEZE) {
2548 0 : spin_unlock_irq(¤t->sighand->siglock);
2549 : return;
2550 : }
2551 :
2552 : /*
2553 : * Now we're sure that there is no pending fatal signal and no
2554 : * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2555 : * immediately (if there is a non-fatal signal pending), and
2556 : * put the task into sleep.
2557 : */
2558 0 : __set_current_state(TASK_INTERRUPTIBLE);
2559 0 : clear_thread_flag(TIF_SIGPENDING);
2560 0 : spin_unlock_irq(¤t->sighand->siglock);
2561 : cgroup_enter_frozen();
2562 0 : freezable_schedule();
2563 : }
2564 :
2565 0 : static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2566 : {
2567 : /*
2568 : * We do not check sig_kernel_stop(signr) but set this marker
2569 : * unconditionally because we do not know whether debugger will
2570 : * change signr. This flag has no meaning unless we are going
2571 : * to stop after return from ptrace_stop(). In this case it will
2572 : * be checked in do_signal_stop(), we should only stop if it was
2573 : * not cleared by SIGCONT while we were sleeping. See also the
2574 : * comment in dequeue_signal().
2575 : */
2576 0 : current->jobctl |= JOBCTL_STOP_DEQUEUED;
2577 0 : signr = ptrace_stop(signr, CLD_TRAPPED, 0, 0, info);
2578 :
2579 : /* We're back. Did the debugger cancel the sig? */
2580 0 : if (signr == 0)
2581 : return signr;
2582 :
2583 : /*
2584 : * Update the siginfo structure if the signal has
2585 : * changed. If the debugger wanted something
2586 : * specific in the siginfo structure then it should
2587 : * have updated *info via PTRACE_SETSIGINFO.
2588 : */
2589 0 : if (signr != info->si_signo) {
2590 0 : clear_siginfo(info);
2591 0 : info->si_signo = signr;
2592 0 : info->si_errno = 0;
2593 0 : info->si_code = SI_USER;
2594 : rcu_read_lock();
2595 0 : info->si_pid = task_pid_vnr(current->parent);
2596 0 : info->si_uid = from_kuid_munged(current_user_ns(),
2597 0 : task_uid(current->parent));
2598 : rcu_read_unlock();
2599 : }
2600 :
2601 : /* If the (new) signal is now blocked, requeue it. */
2602 0 : if (sigismember(¤t->blocked, signr) ||
2603 0 : fatal_signal_pending(current)) {
2604 0 : send_signal(signr, info, current, type);
2605 0 : signr = 0;
2606 : }
2607 :
2608 : return signr;
2609 : }
2610 :
2611 : static void hide_si_addr_tag_bits(struct ksignal *ksig)
2612 : {
2613 : switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2614 : case SIL_FAULT:
2615 : case SIL_FAULT_TRAPNO:
2616 : case SIL_FAULT_MCEERR:
2617 : case SIL_FAULT_BNDERR:
2618 : case SIL_FAULT_PKUERR:
2619 : case SIL_FAULT_PERF_EVENT:
2620 : ksig->info.si_addr = arch_untagged_si_addr(
2621 : ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2622 : break;
2623 : case SIL_KILL:
2624 : case SIL_TIMER:
2625 : case SIL_POLL:
2626 : case SIL_CHLD:
2627 : case SIL_RT:
2628 : case SIL_SYS:
2629 : break;
2630 : }
2631 : }
2632 :
2633 0 : bool get_signal(struct ksignal *ksig)
2634 : {
2635 0 : struct sighand_struct *sighand = current->sighand;
2636 0 : struct signal_struct *signal = current->signal;
2637 : int signr;
2638 :
2639 0 : clear_notify_signal();
2640 0 : if (unlikely(task_work_pending(current)))
2641 0 : task_work_run();
2642 :
2643 0 : if (!task_sigpending(current))
2644 : return false;
2645 :
2646 : if (unlikely(uprobe_deny_signal()))
2647 : return false;
2648 :
2649 : /*
2650 : * Do this once, we can't return to user-mode if freezing() == T.
2651 : * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2652 : * thus do not need another check after return.
2653 : */
2654 : try_to_freeze();
2655 :
2656 : relock:
2657 0 : spin_lock_irq(&sighand->siglock);
2658 :
2659 : /*
2660 : * Every stopped thread goes here after wakeup. Check to see if
2661 : * we should notify the parent, prepare_signal(SIGCONT) encodes
2662 : * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2663 : */
2664 0 : if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2665 : int why;
2666 :
2667 0 : if (signal->flags & SIGNAL_CLD_CONTINUED)
2668 : why = CLD_CONTINUED;
2669 : else
2670 0 : why = CLD_STOPPED;
2671 :
2672 0 : signal->flags &= ~SIGNAL_CLD_MASK;
2673 :
2674 0 : spin_unlock_irq(&sighand->siglock);
2675 :
2676 : /*
2677 : * Notify the parent that we're continuing. This event is
2678 : * always per-process and doesn't make whole lot of sense
2679 : * for ptracers, who shouldn't consume the state via
2680 : * wait(2) either, but, for backward compatibility, notify
2681 : * the ptracer of the group leader too unless it's gonna be
2682 : * a duplicate.
2683 : */
2684 0 : read_lock(&tasklist_lock);
2685 0 : do_notify_parent_cldstop(current, false, why);
2686 :
2687 0 : if (ptrace_reparented(current->group_leader))
2688 0 : do_notify_parent_cldstop(current->group_leader,
2689 : true, why);
2690 0 : read_unlock(&tasklist_lock);
2691 :
2692 0 : goto relock;
2693 : }
2694 :
2695 0 : for (;;) {
2696 : struct k_sigaction *ka;
2697 : enum pid_type type;
2698 :
2699 : /* Has this task already been marked for death? */
2700 0 : if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2701 0 : signal->group_exec_task) {
2702 0 : ksig->info.si_signo = signr = SIGKILL;
2703 0 : sigdelset(¤t->pending.signal, SIGKILL);
2704 0 : trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2705 : &sighand->action[SIGKILL - 1]);
2706 0 : recalc_sigpending();
2707 0 : goto fatal;
2708 : }
2709 :
2710 0 : if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2711 0 : do_signal_stop(0))
2712 : goto relock;
2713 :
2714 0 : if (unlikely(current->jobctl &
2715 : (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2716 0 : if (current->jobctl & JOBCTL_TRAP_MASK) {
2717 0 : do_jobctl_trap();
2718 0 : spin_unlock_irq(&sighand->siglock);
2719 0 : } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2720 0 : do_freezer_trap();
2721 :
2722 : goto relock;
2723 : }
2724 :
2725 : /*
2726 : * If the task is leaving the frozen state, let's update
2727 : * cgroup counters and reset the frozen bit.
2728 : */
2729 0 : if (unlikely(cgroup_task_frozen(current))) {
2730 : spin_unlock_irq(&sighand->siglock);
2731 : cgroup_leave_frozen(false);
2732 : goto relock;
2733 : }
2734 :
2735 : /*
2736 : * Signals generated by the execution of an instruction
2737 : * need to be delivered before any other pending signals
2738 : * so that the instruction pointer in the signal stack
2739 : * frame points to the faulting instruction.
2740 : */
2741 0 : type = PIDTYPE_PID;
2742 0 : signr = dequeue_synchronous_signal(&ksig->info);
2743 0 : if (!signr)
2744 0 : signr = dequeue_signal(current, ¤t->blocked,
2745 : &ksig->info, &type);
2746 :
2747 0 : if (!signr)
2748 : break; /* will return 0 */
2749 :
2750 0 : if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2751 0 : !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2752 0 : signr = ptrace_signal(signr, &ksig->info, type);
2753 0 : if (!signr)
2754 0 : continue;
2755 : }
2756 :
2757 0 : ka = &sighand->action[signr-1];
2758 :
2759 : /* Trace actually delivered signals. */
2760 0 : trace_signal_deliver(signr, &ksig->info, ka);
2761 :
2762 0 : if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
2763 0 : continue;
2764 0 : if (ka->sa.sa_handler != SIG_DFL) {
2765 : /* Run the handler. */
2766 0 : ksig->ka = *ka;
2767 :
2768 0 : if (ka->sa.sa_flags & SA_ONESHOT)
2769 0 : ka->sa.sa_handler = SIG_DFL;
2770 :
2771 : break; /* will return non-zero "signr" value */
2772 : }
2773 :
2774 : /*
2775 : * Now we are doing the default action for this signal.
2776 : */
2777 0 : if (sig_kernel_ignore(signr)) /* Default is nothing. */
2778 0 : continue;
2779 :
2780 : /*
2781 : * Global init gets no signals it doesn't want.
2782 : * Container-init gets no signals it doesn't want from same
2783 : * container.
2784 : *
2785 : * Note that if global/container-init sees a sig_kernel_only()
2786 : * signal here, the signal must have been generated internally
2787 : * or must have come from an ancestor namespace. In either
2788 : * case, the signal cannot be dropped.
2789 : */
2790 0 : if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2791 0 : !sig_kernel_only(signr))
2792 0 : continue;
2793 :
2794 0 : if (sig_kernel_stop(signr)) {
2795 : /*
2796 : * The default action is to stop all threads in
2797 : * the thread group. The job control signals
2798 : * do nothing in an orphaned pgrp, but SIGSTOP
2799 : * always works. Note that siglock needs to be
2800 : * dropped during the call to is_orphaned_pgrp()
2801 : * because of lock ordering with tasklist_lock.
2802 : * This allows an intervening SIGCONT to be posted.
2803 : * We need to check for that and bail out if necessary.
2804 : */
2805 0 : if (signr != SIGSTOP) {
2806 0 : spin_unlock_irq(&sighand->siglock);
2807 :
2808 : /* signals can be posted during this window */
2809 :
2810 0 : if (is_current_pgrp_orphaned())
2811 : goto relock;
2812 :
2813 0 : spin_lock_irq(&sighand->siglock);
2814 : }
2815 :
2816 0 : if (likely(do_signal_stop(ksig->info.si_signo))) {
2817 : /* It released the siglock. */
2818 : goto relock;
2819 : }
2820 :
2821 : /*
2822 : * We didn't actually stop, due to a race
2823 : * with SIGCONT or something like that.
2824 : */
2825 0 : continue;
2826 : }
2827 :
2828 : fatal:
2829 0 : spin_unlock_irq(&sighand->siglock);
2830 0 : if (unlikely(cgroup_task_frozen(current)))
2831 : cgroup_leave_frozen(true);
2832 :
2833 : /*
2834 : * Anything else is fatal, maybe with a core dump.
2835 : */
2836 0 : current->flags |= PF_SIGNALED;
2837 :
2838 0 : if (sig_kernel_coredump(signr)) {
2839 0 : if (print_fatal_signals)
2840 0 : print_fatal_signal(ksig->info.si_signo);
2841 0 : proc_coredump_connector(current);
2842 : /*
2843 : * If it was able to dump core, this kills all
2844 : * other threads in the group and synchronizes with
2845 : * their demise. If we lost the race with another
2846 : * thread getting here, it set group_exit_code
2847 : * first and our do_group_exit call below will use
2848 : * that value and ignore the one we pass it.
2849 : */
2850 0 : do_coredump(&ksig->info);
2851 : }
2852 :
2853 : /*
2854 : * PF_IO_WORKER threads will catch and exit on fatal signals
2855 : * themselves. They have cleanup that must be performed, so
2856 : * we cannot call do_exit() on their behalf.
2857 : */
2858 0 : if (current->flags & PF_IO_WORKER)
2859 : goto out;
2860 :
2861 : /*
2862 : * Death signals, no core dump.
2863 : */
2864 0 : do_group_exit(ksig->info.si_signo);
2865 : /* NOTREACHED */
2866 : }
2867 0 : spin_unlock_irq(&sighand->siglock);
2868 : out:
2869 0 : ksig->sig = signr;
2870 :
2871 : if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2872 : hide_si_addr_tag_bits(ksig);
2873 :
2874 0 : return ksig->sig > 0;
2875 : }
2876 :
2877 : /**
2878 : * signal_delivered - called after signal delivery to update blocked signals
2879 : * @ksig: kernel signal struct
2880 : * @stepping: nonzero if debugger single-step or block-step in use
2881 : *
2882 : * This function should be called when a signal has successfully been
2883 : * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2884 : * is always blocked), and the signal itself is blocked unless %SA_NODEFER
2885 : * is set in @ksig->ka.sa.sa_flags. Tracing is notified.
2886 : */
2887 0 : static void signal_delivered(struct ksignal *ksig, int stepping)
2888 : {
2889 : sigset_t blocked;
2890 :
2891 : /* A signal was successfully delivered, and the
2892 : saved sigmask was stored on the signal frame,
2893 : and will be restored by sigreturn. So we can
2894 : simply clear the restore sigmask flag. */
2895 0 : clear_restore_sigmask();
2896 :
2897 0 : sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask);
2898 0 : if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2899 0 : sigaddset(&blocked, ksig->sig);
2900 0 : set_current_blocked(&blocked);
2901 0 : if (current->sas_ss_flags & SS_AUTODISARM)
2902 0 : sas_ss_reset(current);
2903 0 : if (stepping)
2904 0 : ptrace_notify(SIGTRAP, 0);
2905 0 : }
2906 :
2907 0 : void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2908 : {
2909 0 : if (failed)
2910 0 : force_sigsegv(ksig->sig);
2911 : else
2912 0 : signal_delivered(ksig, stepping);
2913 0 : }
2914 :
2915 : /*
2916 : * It could be that complete_signal() picked us to notify about the
2917 : * group-wide signal. Other threads should be notified now to take
2918 : * the shared signals in @which since we will not.
2919 : */
2920 0 : static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2921 : {
2922 : sigset_t retarget;
2923 : struct task_struct *t;
2924 :
2925 0 : sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2926 0 : if (sigisemptyset(&retarget))
2927 : return;
2928 :
2929 : t = tsk;
2930 0 : while_each_thread(tsk, t) {
2931 0 : if (t->flags & PF_EXITING)
2932 0 : continue;
2933 :
2934 0 : if (!has_pending_signals(&retarget, &t->blocked))
2935 0 : continue;
2936 : /* Remove the signals this thread can handle. */
2937 0 : sigandsets(&retarget, &retarget, &t->blocked);
2938 :
2939 0 : if (!task_sigpending(t))
2940 : signal_wake_up(t, 0);
2941 :
2942 0 : if (sigisemptyset(&retarget))
2943 : break;
2944 : }
2945 : }
2946 :
2947 93 : void exit_signals(struct task_struct *tsk)
2948 : {
2949 93 : int group_stop = 0;
2950 : sigset_t unblocked;
2951 :
2952 : /*
2953 : * @tsk is about to have PF_EXITING set - lock out users which
2954 : * expect stable threadgroup.
2955 : */
2956 93 : cgroup_threadgroup_change_begin(tsk);
2957 :
2958 93 : if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
2959 93 : tsk->flags |= PF_EXITING;
2960 93 : cgroup_threadgroup_change_end(tsk);
2961 93 : return;
2962 : }
2963 :
2964 0 : spin_lock_irq(&tsk->sighand->siglock);
2965 : /*
2966 : * From now this task is not visible for group-wide signals,
2967 : * see wants_signal(), do_signal_stop().
2968 : */
2969 0 : tsk->flags |= PF_EXITING;
2970 :
2971 0 : cgroup_threadgroup_change_end(tsk);
2972 :
2973 0 : if (!task_sigpending(tsk))
2974 : goto out;
2975 :
2976 0 : unblocked = tsk->blocked;
2977 0 : signotset(&unblocked);
2978 0 : retarget_shared_pending(tsk, &unblocked);
2979 :
2980 0 : if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2981 0 : task_participate_group_stop(tsk))
2982 0 : group_stop = CLD_STOPPED;
2983 : out:
2984 0 : spin_unlock_irq(&tsk->sighand->siglock);
2985 :
2986 : /*
2987 : * If group stop has completed, deliver the notification. This
2988 : * should always go to the real parent of the group leader.
2989 : */
2990 0 : if (unlikely(group_stop)) {
2991 0 : read_lock(&tasklist_lock);
2992 0 : do_notify_parent_cldstop(tsk, false, group_stop);
2993 0 : read_unlock(&tasklist_lock);
2994 : }
2995 : }
2996 :
2997 : /*
2998 : * System call entry points.
2999 : */
3000 :
3001 : /**
3002 : * sys_restart_syscall - restart a system call
3003 : */
3004 0 : SYSCALL_DEFINE0(restart_syscall)
3005 : {
3006 0 : struct restart_block *restart = ¤t->restart_block;
3007 0 : return restart->fn(restart);
3008 : }
3009 :
3010 0 : long do_no_restart_syscall(struct restart_block *param)
3011 : {
3012 0 : return -EINTR;
3013 : }
3014 :
3015 0 : static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3016 : {
3017 0 : if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
3018 : sigset_t newblocked;
3019 : /* A set of now blocked but previously unblocked signals. */
3020 0 : sigandnsets(&newblocked, newset, ¤t->blocked);
3021 0 : retarget_shared_pending(tsk, &newblocked);
3022 : }
3023 0 : tsk->blocked = *newset;
3024 0 : recalc_sigpending();
3025 0 : }
3026 :
3027 : /**
3028 : * set_current_blocked - change current->blocked mask
3029 : * @newset: new mask
3030 : *
3031 : * It is wrong to change ->blocked directly, this helper should be used
3032 : * to ensure the process can't miss a shared signal we are going to block.
3033 : */
3034 0 : void set_current_blocked(sigset_t *newset)
3035 : {
3036 0 : sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3037 0 : __set_current_blocked(newset);
3038 0 : }
3039 :
3040 0 : void __set_current_blocked(const sigset_t *newset)
3041 : {
3042 0 : struct task_struct *tsk = current;
3043 :
3044 : /*
3045 : * In case the signal mask hasn't changed, there is nothing we need
3046 : * to do. The current->blocked shouldn't be modified by other task.
3047 : */
3048 0 : if (sigequalsets(&tsk->blocked, newset))
3049 : return;
3050 :
3051 0 : spin_lock_irq(&tsk->sighand->siglock);
3052 0 : __set_task_blocked(tsk, newset);
3053 0 : spin_unlock_irq(&tsk->sighand->siglock);
3054 : }
3055 :
3056 : /*
3057 : * This is also useful for kernel threads that want to temporarily
3058 : * (or permanently) block certain signals.
3059 : *
3060 : * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3061 : * interface happily blocks "unblockable" signals like SIGKILL
3062 : * and friends.
3063 : */
3064 0 : int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3065 : {
3066 0 : struct task_struct *tsk = current;
3067 : sigset_t newset;
3068 :
3069 : /* Lockless, only current can change ->blocked, never from irq */
3070 0 : if (oldset)
3071 0 : *oldset = tsk->blocked;
3072 :
3073 0 : switch (how) {
3074 : case SIG_BLOCK:
3075 0 : sigorsets(&newset, &tsk->blocked, set);
3076 : break;
3077 : case SIG_UNBLOCK:
3078 0 : sigandnsets(&newset, &tsk->blocked, set);
3079 : break;
3080 : case SIG_SETMASK:
3081 0 : newset = *set;
3082 0 : break;
3083 : default:
3084 : return -EINVAL;
3085 : }
3086 :
3087 0 : __set_current_blocked(&newset);
3088 0 : return 0;
3089 : }
3090 : EXPORT_SYMBOL(sigprocmask);
3091 :
3092 : /*
3093 : * The api helps set app-provided sigmasks.
3094 : *
3095 : * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3096 : * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3097 : *
3098 : * Note that it does set_restore_sigmask() in advance, so it must be always
3099 : * paired with restore_saved_sigmask_unless() before return from syscall.
3100 : */
3101 0 : int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3102 : {
3103 : sigset_t kmask;
3104 :
3105 0 : if (!umask)
3106 : return 0;
3107 0 : if (sigsetsize != sizeof(sigset_t))
3108 : return -EINVAL;
3109 0 : if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3110 : return -EFAULT;
3111 :
3112 0 : set_restore_sigmask();
3113 0 : current->saved_sigmask = current->blocked;
3114 0 : set_current_blocked(&kmask);
3115 :
3116 0 : return 0;
3117 : }
3118 :
3119 : #ifdef CONFIG_COMPAT
3120 : int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3121 : size_t sigsetsize)
3122 : {
3123 : sigset_t kmask;
3124 :
3125 : if (!umask)
3126 : return 0;
3127 : if (sigsetsize != sizeof(compat_sigset_t))
3128 : return -EINVAL;
3129 : if (get_compat_sigset(&kmask, umask))
3130 : return -EFAULT;
3131 :
3132 : set_restore_sigmask();
3133 : current->saved_sigmask = current->blocked;
3134 : set_current_blocked(&kmask);
3135 :
3136 : return 0;
3137 : }
3138 : #endif
3139 :
3140 : /**
3141 : * sys_rt_sigprocmask - change the list of currently blocked signals
3142 : * @how: whether to add, remove, or set signals
3143 : * @nset: stores pending signals
3144 : * @oset: previous value of signal mask if non-null
3145 : * @sigsetsize: size of sigset_t type
3146 : */
3147 0 : SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3148 : sigset_t __user *, oset, size_t, sigsetsize)
3149 : {
3150 : sigset_t old_set, new_set;
3151 : int error;
3152 :
3153 : /* XXX: Don't preclude handling different sized sigset_t's. */
3154 0 : if (sigsetsize != sizeof(sigset_t))
3155 : return -EINVAL;
3156 :
3157 0 : old_set = current->blocked;
3158 :
3159 0 : if (nset) {
3160 0 : if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3161 : return -EFAULT;
3162 0 : sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3163 :
3164 0 : error = sigprocmask(how, &new_set, NULL);
3165 0 : if (error)
3166 0 : return error;
3167 : }
3168 :
3169 0 : if (oset) {
3170 0 : if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3171 : return -EFAULT;
3172 : }
3173 :
3174 : return 0;
3175 : }
3176 :
3177 : #ifdef CONFIG_COMPAT
3178 : COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3179 : compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3180 : {
3181 : sigset_t old_set = current->blocked;
3182 :
3183 : /* XXX: Don't preclude handling different sized sigset_t's. */
3184 : if (sigsetsize != sizeof(sigset_t))
3185 : return -EINVAL;
3186 :
3187 : if (nset) {
3188 : sigset_t new_set;
3189 : int error;
3190 : if (get_compat_sigset(&new_set, nset))
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 : return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3199 : }
3200 : #endif
3201 :
3202 0 : static void do_sigpending(sigset_t *set)
3203 : {
3204 0 : spin_lock_irq(¤t->sighand->siglock);
3205 0 : sigorsets(set, ¤t->pending.signal,
3206 0 : ¤t->signal->shared_pending.signal);
3207 0 : spin_unlock_irq(¤t->sighand->siglock);
3208 :
3209 : /* Outside the lock because only this thread touches it. */
3210 0 : sigandsets(set, ¤t->blocked, set);
3211 0 : }
3212 :
3213 : /**
3214 : * sys_rt_sigpending - examine a pending signal that has been raised
3215 : * while blocked
3216 : * @uset: stores pending signals
3217 : * @sigsetsize: size of sigset_t type or larger
3218 : */
3219 0 : SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3220 : {
3221 : sigset_t set;
3222 :
3223 0 : if (sigsetsize > sizeof(*uset))
3224 : return -EINVAL;
3225 :
3226 0 : do_sigpending(&set);
3227 :
3228 0 : if (copy_to_user(uset, &set, sigsetsize))
3229 : return -EFAULT;
3230 :
3231 0 : return 0;
3232 : }
3233 :
3234 : #ifdef CONFIG_COMPAT
3235 : COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3236 : compat_size_t, sigsetsize)
3237 : {
3238 : sigset_t set;
3239 :
3240 : if (sigsetsize > sizeof(*uset))
3241 : return -EINVAL;
3242 :
3243 : do_sigpending(&set);
3244 :
3245 : return put_compat_sigset(uset, &set, sigsetsize);
3246 : }
3247 : #endif
3248 :
3249 : static const struct {
3250 : unsigned char limit, layout;
3251 : } sig_sicodes[] = {
3252 : [SIGILL] = { NSIGILL, SIL_FAULT },
3253 : [SIGFPE] = { NSIGFPE, SIL_FAULT },
3254 : [SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3255 : [SIGBUS] = { NSIGBUS, SIL_FAULT },
3256 : [SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3257 : #if defined(SIGEMT)
3258 : [SIGEMT] = { NSIGEMT, SIL_FAULT },
3259 : #endif
3260 : [SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3261 : [SIGPOLL] = { NSIGPOLL, SIL_POLL },
3262 : [SIGSYS] = { NSIGSYS, SIL_SYS },
3263 : };
3264 :
3265 0 : static bool known_siginfo_layout(unsigned sig, int si_code)
3266 : {
3267 0 : if (si_code == SI_KERNEL)
3268 : return true;
3269 0 : else if ((si_code > SI_USER)) {
3270 0 : if (sig_specific_sicodes(sig)) {
3271 0 : if (si_code <= sig_sicodes[sig].limit)
3272 : return true;
3273 : }
3274 0 : else if (si_code <= NSIGPOLL)
3275 : return true;
3276 : }
3277 0 : else if (si_code >= SI_DETHREAD)
3278 : return true;
3279 0 : else if (si_code == SI_ASYNCNL)
3280 : return true;
3281 0 : return false;
3282 : }
3283 :
3284 0 : enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3285 : {
3286 0 : enum siginfo_layout layout = SIL_KILL;
3287 0 : if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3288 0 : if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3289 0 : (si_code <= sig_sicodes[sig].limit)) {
3290 0 : layout = sig_sicodes[sig].layout;
3291 : /* Handle the exceptions */
3292 0 : if ((sig == SIGBUS) &&
3293 0 : (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3294 : layout = SIL_FAULT_MCEERR;
3295 0 : else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3296 : layout = SIL_FAULT_BNDERR;
3297 : #ifdef SEGV_PKUERR
3298 0 : else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3299 : layout = SIL_FAULT_PKUERR;
3300 : #endif
3301 0 : else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3302 0 : layout = SIL_FAULT_PERF_EVENT;
3303 : else if (IS_ENABLED(CONFIG_SPARC) &&
3304 : (sig == SIGILL) && (si_code == ILL_ILLTRP))
3305 : layout = SIL_FAULT_TRAPNO;
3306 : else if (IS_ENABLED(CONFIG_ALPHA) &&
3307 : ((sig == SIGFPE) ||
3308 : ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3309 : layout = SIL_FAULT_TRAPNO;
3310 : }
3311 0 : else if (si_code <= NSIGPOLL)
3312 0 : layout = SIL_POLL;
3313 : } else {
3314 0 : if (si_code == SI_TIMER)
3315 : layout = SIL_TIMER;
3316 0 : else if (si_code == SI_SIGIO)
3317 : layout = SIL_POLL;
3318 0 : else if (si_code < 0)
3319 0 : layout = SIL_RT;
3320 : }
3321 0 : return layout;
3322 : }
3323 :
3324 : static inline char __user *si_expansion(const siginfo_t __user *info)
3325 : {
3326 0 : return ((char __user *)info) + sizeof(struct kernel_siginfo);
3327 : }
3328 :
3329 0 : int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3330 : {
3331 0 : char __user *expansion = si_expansion(to);
3332 0 : if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3333 : return -EFAULT;
3334 0 : if (clear_user(expansion, SI_EXPANSION_SIZE))
3335 : return -EFAULT;
3336 0 : return 0;
3337 : }
3338 :
3339 0 : static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3340 : const siginfo_t __user *from)
3341 : {
3342 0 : if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3343 0 : char __user *expansion = si_expansion(from);
3344 : char buf[SI_EXPANSION_SIZE];
3345 : int i;
3346 : /*
3347 : * An unknown si_code might need more than
3348 : * sizeof(struct kernel_siginfo) bytes. Verify all of the
3349 : * extra bytes are 0. This guarantees copy_siginfo_to_user
3350 : * will return this data to userspace exactly.
3351 : */
3352 0 : if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3353 0 : return -EFAULT;
3354 0 : for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3355 0 : if (buf[i] != 0)
3356 : return -E2BIG;
3357 : }
3358 : }
3359 : return 0;
3360 : }
3361 :
3362 0 : static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3363 : const siginfo_t __user *from)
3364 : {
3365 0 : if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3366 : return -EFAULT;
3367 0 : to->si_signo = signo;
3368 0 : return post_copy_siginfo_from_user(to, from);
3369 : }
3370 :
3371 0 : int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
3372 : {
3373 0 : if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3374 : return -EFAULT;
3375 0 : return post_copy_siginfo_from_user(to, from);
3376 : }
3377 :
3378 : #ifdef CONFIG_COMPAT
3379 : /**
3380 : * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3381 : * @to: compat siginfo destination
3382 : * @from: kernel siginfo source
3383 : *
3384 : * Note: This function does not work properly for the SIGCHLD on x32, but
3385 : * fortunately it doesn't have to. The only valid callers for this function are
3386 : * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3387 : * The latter does not care because SIGCHLD will never cause a coredump.
3388 : */
3389 : void copy_siginfo_to_external32(struct compat_siginfo *to,
3390 : const struct kernel_siginfo *from)
3391 : {
3392 : memset(to, 0, sizeof(*to));
3393 :
3394 : to->si_signo = from->si_signo;
3395 : to->si_errno = from->si_errno;
3396 : to->si_code = from->si_code;
3397 : switch(siginfo_layout(from->si_signo, from->si_code)) {
3398 : case SIL_KILL:
3399 : to->si_pid = from->si_pid;
3400 : to->si_uid = from->si_uid;
3401 : break;
3402 : case SIL_TIMER:
3403 : to->si_tid = from->si_tid;
3404 : to->si_overrun = from->si_overrun;
3405 : to->si_int = from->si_int;
3406 : break;
3407 : case SIL_POLL:
3408 : to->si_band = from->si_band;
3409 : to->si_fd = from->si_fd;
3410 : break;
3411 : case SIL_FAULT:
3412 : to->si_addr = ptr_to_compat(from->si_addr);
3413 : break;
3414 : case SIL_FAULT_TRAPNO:
3415 : to->si_addr = ptr_to_compat(from->si_addr);
3416 : to->si_trapno = from->si_trapno;
3417 : break;
3418 : case SIL_FAULT_MCEERR:
3419 : to->si_addr = ptr_to_compat(from->si_addr);
3420 : to->si_addr_lsb = from->si_addr_lsb;
3421 : break;
3422 : case SIL_FAULT_BNDERR:
3423 : to->si_addr = ptr_to_compat(from->si_addr);
3424 : to->si_lower = ptr_to_compat(from->si_lower);
3425 : to->si_upper = ptr_to_compat(from->si_upper);
3426 : break;
3427 : case SIL_FAULT_PKUERR:
3428 : to->si_addr = ptr_to_compat(from->si_addr);
3429 : to->si_pkey = from->si_pkey;
3430 : break;
3431 : case SIL_FAULT_PERF_EVENT:
3432 : to->si_addr = ptr_to_compat(from->si_addr);
3433 : to->si_perf_data = from->si_perf_data;
3434 : to->si_perf_type = from->si_perf_type;
3435 : break;
3436 : case SIL_CHLD:
3437 : to->si_pid = from->si_pid;
3438 : to->si_uid = from->si_uid;
3439 : to->si_status = from->si_status;
3440 : to->si_utime = from->si_utime;
3441 : to->si_stime = from->si_stime;
3442 : break;
3443 : case SIL_RT:
3444 : to->si_pid = from->si_pid;
3445 : to->si_uid = from->si_uid;
3446 : to->si_int = from->si_int;
3447 : break;
3448 : case SIL_SYS:
3449 : to->si_call_addr = ptr_to_compat(from->si_call_addr);
3450 : to->si_syscall = from->si_syscall;
3451 : to->si_arch = from->si_arch;
3452 : break;
3453 : }
3454 : }
3455 :
3456 : int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3457 : const struct kernel_siginfo *from)
3458 : {
3459 : struct compat_siginfo new;
3460 :
3461 : copy_siginfo_to_external32(&new, from);
3462 : if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3463 : return -EFAULT;
3464 : return 0;
3465 : }
3466 :
3467 : static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3468 : const struct compat_siginfo *from)
3469 : {
3470 : clear_siginfo(to);
3471 : to->si_signo = from->si_signo;
3472 : to->si_errno = from->si_errno;
3473 : to->si_code = from->si_code;
3474 : switch(siginfo_layout(from->si_signo, from->si_code)) {
3475 : case SIL_KILL:
3476 : to->si_pid = from->si_pid;
3477 : to->si_uid = from->si_uid;
3478 : break;
3479 : case SIL_TIMER:
3480 : to->si_tid = from->si_tid;
3481 : to->si_overrun = from->si_overrun;
3482 : to->si_int = from->si_int;
3483 : break;
3484 : case SIL_POLL:
3485 : to->si_band = from->si_band;
3486 : to->si_fd = from->si_fd;
3487 : break;
3488 : case SIL_FAULT:
3489 : to->si_addr = compat_ptr(from->si_addr);
3490 : break;
3491 : case SIL_FAULT_TRAPNO:
3492 : to->si_addr = compat_ptr(from->si_addr);
3493 : to->si_trapno = from->si_trapno;
3494 : break;
3495 : case SIL_FAULT_MCEERR:
3496 : to->si_addr = compat_ptr(from->si_addr);
3497 : to->si_addr_lsb = from->si_addr_lsb;
3498 : break;
3499 : case SIL_FAULT_BNDERR:
3500 : to->si_addr = compat_ptr(from->si_addr);
3501 : to->si_lower = compat_ptr(from->si_lower);
3502 : to->si_upper = compat_ptr(from->si_upper);
3503 : break;
3504 : case SIL_FAULT_PKUERR:
3505 : to->si_addr = compat_ptr(from->si_addr);
3506 : to->si_pkey = from->si_pkey;
3507 : break;
3508 : case SIL_FAULT_PERF_EVENT:
3509 : to->si_addr = compat_ptr(from->si_addr);
3510 : to->si_perf_data = from->si_perf_data;
3511 : to->si_perf_type = from->si_perf_type;
3512 : break;
3513 : case SIL_CHLD:
3514 : to->si_pid = from->si_pid;
3515 : to->si_uid = from->si_uid;
3516 : to->si_status = from->si_status;
3517 : #ifdef CONFIG_X86_X32_ABI
3518 : if (in_x32_syscall()) {
3519 : to->si_utime = from->_sifields._sigchld_x32._utime;
3520 : to->si_stime = from->_sifields._sigchld_x32._stime;
3521 : } else
3522 : #endif
3523 : {
3524 : to->si_utime = from->si_utime;
3525 : to->si_stime = from->si_stime;
3526 : }
3527 : break;
3528 : case SIL_RT:
3529 : to->si_pid = from->si_pid;
3530 : to->si_uid = from->si_uid;
3531 : to->si_int = from->si_int;
3532 : break;
3533 : case SIL_SYS:
3534 : to->si_call_addr = compat_ptr(from->si_call_addr);
3535 : to->si_syscall = from->si_syscall;
3536 : to->si_arch = from->si_arch;
3537 : break;
3538 : }
3539 : return 0;
3540 : }
3541 :
3542 : static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3543 : const struct compat_siginfo __user *ufrom)
3544 : {
3545 : struct compat_siginfo from;
3546 :
3547 : if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3548 : return -EFAULT;
3549 :
3550 : from.si_signo = signo;
3551 : return post_copy_siginfo_from_user32(to, &from);
3552 : }
3553 :
3554 : int copy_siginfo_from_user32(struct kernel_siginfo *to,
3555 : const struct compat_siginfo __user *ufrom)
3556 : {
3557 : struct compat_siginfo from;
3558 :
3559 : if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3560 : return -EFAULT;
3561 :
3562 : return post_copy_siginfo_from_user32(to, &from);
3563 : }
3564 : #endif /* CONFIG_COMPAT */
3565 :
3566 : /**
3567 : * do_sigtimedwait - wait for queued signals specified in @which
3568 : * @which: queued signals to wait for
3569 : * @info: if non-null, the signal's siginfo is returned here
3570 : * @ts: upper bound on process time suspension
3571 : */
3572 0 : static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3573 : const struct timespec64 *ts)
3574 : {
3575 0 : ktime_t *to = NULL, timeout = KTIME_MAX;
3576 0 : struct task_struct *tsk = current;
3577 0 : sigset_t mask = *which;
3578 : enum pid_type type;
3579 0 : int sig, ret = 0;
3580 :
3581 0 : if (ts) {
3582 0 : if (!timespec64_valid(ts))
3583 : return -EINVAL;
3584 0 : timeout = timespec64_to_ktime(*ts);
3585 0 : to = &timeout;
3586 : }
3587 :
3588 : /*
3589 : * Invert the set of allowed signals to get those we want to block.
3590 : */
3591 0 : sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3592 0 : signotset(&mask);
3593 :
3594 0 : spin_lock_irq(&tsk->sighand->siglock);
3595 0 : sig = dequeue_signal(tsk, &mask, info, &type);
3596 0 : if (!sig && timeout) {
3597 : /*
3598 : * None ready, temporarily unblock those we're interested
3599 : * while we are sleeping in so that we'll be awakened when
3600 : * they arrive. Unblocking is always fine, we can avoid
3601 : * set_current_blocked().
3602 : */
3603 0 : tsk->real_blocked = tsk->blocked;
3604 0 : sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3605 0 : recalc_sigpending();
3606 0 : spin_unlock_irq(&tsk->sighand->siglock);
3607 :
3608 0 : __set_current_state(TASK_INTERRUPTIBLE);
3609 0 : ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3610 : HRTIMER_MODE_REL);
3611 0 : spin_lock_irq(&tsk->sighand->siglock);
3612 0 : __set_task_blocked(tsk, &tsk->real_blocked);
3613 0 : sigemptyset(&tsk->real_blocked);
3614 0 : sig = dequeue_signal(tsk, &mask, info, &type);
3615 : }
3616 0 : spin_unlock_irq(&tsk->sighand->siglock);
3617 :
3618 0 : if (sig)
3619 : return sig;
3620 0 : return ret ? -EINTR : -EAGAIN;
3621 : }
3622 :
3623 : /**
3624 : * sys_rt_sigtimedwait - synchronously wait for queued signals specified
3625 : * in @uthese
3626 : * @uthese: queued signals to wait for
3627 : * @uinfo: if non-null, the signal's siginfo is returned here
3628 : * @uts: upper bound on process time suspension
3629 : * @sigsetsize: size of sigset_t type
3630 : */
3631 0 : SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3632 : siginfo_t __user *, uinfo,
3633 : const struct __kernel_timespec __user *, uts,
3634 : size_t, sigsetsize)
3635 : {
3636 : sigset_t these;
3637 : struct timespec64 ts;
3638 : kernel_siginfo_t info;
3639 : int ret;
3640 :
3641 : /* XXX: Don't preclude handling different sized sigset_t's. */
3642 0 : if (sigsetsize != sizeof(sigset_t))
3643 : return -EINVAL;
3644 :
3645 0 : if (copy_from_user(&these, uthese, sizeof(these)))
3646 : return -EFAULT;
3647 :
3648 0 : if (uts) {
3649 0 : if (get_timespec64(&ts, uts))
3650 : return -EFAULT;
3651 : }
3652 :
3653 0 : ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3654 :
3655 0 : if (ret > 0 && uinfo) {
3656 0 : if (copy_siginfo_to_user(uinfo, &info))
3657 0 : ret = -EFAULT;
3658 : }
3659 :
3660 0 : return ret;
3661 : }
3662 :
3663 : #ifdef CONFIG_COMPAT_32BIT_TIME
3664 : SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3665 : siginfo_t __user *, uinfo,
3666 : const struct old_timespec32 __user *, uts,
3667 : size_t, sigsetsize)
3668 : {
3669 : sigset_t these;
3670 : struct timespec64 ts;
3671 : kernel_siginfo_t info;
3672 : int ret;
3673 :
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_old_timespec32(&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 : #endif
3695 :
3696 : #ifdef CONFIG_COMPAT
3697 : COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3698 : struct compat_siginfo __user *, uinfo,
3699 : struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3700 : {
3701 : sigset_t s;
3702 : struct timespec64 t;
3703 : kernel_siginfo_t info;
3704 : long ret;
3705 :
3706 : if (sigsetsize != sizeof(sigset_t))
3707 : return -EINVAL;
3708 :
3709 : if (get_compat_sigset(&s, uthese))
3710 : return -EFAULT;
3711 :
3712 : if (uts) {
3713 : if (get_timespec64(&t, uts))
3714 : return -EFAULT;
3715 : }
3716 :
3717 : ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3718 :
3719 : if (ret > 0 && uinfo) {
3720 : if (copy_siginfo_to_user32(uinfo, &info))
3721 : ret = -EFAULT;
3722 : }
3723 :
3724 : return ret;
3725 : }
3726 :
3727 : #ifdef CONFIG_COMPAT_32BIT_TIME
3728 : COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3729 : struct compat_siginfo __user *, uinfo,
3730 : struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3731 : {
3732 : sigset_t s;
3733 : struct timespec64 t;
3734 : kernel_siginfo_t info;
3735 : long ret;
3736 :
3737 : if (sigsetsize != sizeof(sigset_t))
3738 : return -EINVAL;
3739 :
3740 : if (get_compat_sigset(&s, uthese))
3741 : return -EFAULT;
3742 :
3743 : if (uts) {
3744 : if (get_old_timespec32(&t, uts))
3745 : return -EFAULT;
3746 : }
3747 :
3748 : ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3749 :
3750 : if (ret > 0 && uinfo) {
3751 : if (copy_siginfo_to_user32(uinfo, &info))
3752 : ret = -EFAULT;
3753 : }
3754 :
3755 : return ret;
3756 : }
3757 : #endif
3758 : #endif
3759 :
3760 0 : static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
3761 : {
3762 0 : clear_siginfo(info);
3763 0 : info->si_signo = sig;
3764 0 : info->si_errno = 0;
3765 0 : info->si_code = SI_USER;
3766 0 : info->si_pid = task_tgid_vnr(current);
3767 0 : info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3768 0 : }
3769 :
3770 : /**
3771 : * sys_kill - send a signal to a process
3772 : * @pid: the PID of the process
3773 : * @sig: signal to be sent
3774 : */
3775 0 : SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3776 : {
3777 : struct kernel_siginfo info;
3778 :
3779 0 : prepare_kill_siginfo(sig, &info);
3780 :
3781 0 : return kill_something_info(sig, &info, pid);
3782 : }
3783 :
3784 : /*
3785 : * Verify that the signaler and signalee either are in the same pid namespace
3786 : * or that the signaler's pid namespace is an ancestor of the signalee's pid
3787 : * namespace.
3788 : */
3789 0 : static bool access_pidfd_pidns(struct pid *pid)
3790 : {
3791 0 : struct pid_namespace *active = task_active_pid_ns(current);
3792 : struct pid_namespace *p = ns_of_pid(pid);
3793 :
3794 : for (;;) {
3795 0 : if (!p)
3796 : return false;
3797 0 : if (p == active)
3798 : break;
3799 0 : p = p->parent;
3800 : }
3801 :
3802 : return true;
3803 : }
3804 :
3805 : static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3806 : siginfo_t __user *info)
3807 : {
3808 : #ifdef CONFIG_COMPAT
3809 : /*
3810 : * Avoid hooking up compat syscalls and instead handle necessary
3811 : * conversions here. Note, this is a stop-gap measure and should not be
3812 : * considered a generic solution.
3813 : */
3814 : if (in_compat_syscall())
3815 : return copy_siginfo_from_user32(
3816 : kinfo, (struct compat_siginfo __user *)info);
3817 : #endif
3818 0 : return copy_siginfo_from_user(kinfo, info);
3819 : }
3820 :
3821 0 : static struct pid *pidfd_to_pid(const struct file *file)
3822 : {
3823 : struct pid *pid;
3824 :
3825 0 : pid = pidfd_pid(file);
3826 0 : if (!IS_ERR(pid))
3827 : return pid;
3828 :
3829 0 : return tgid_pidfd_to_pid(file);
3830 : }
3831 :
3832 : /**
3833 : * sys_pidfd_send_signal - Signal a process through a pidfd
3834 : * @pidfd: file descriptor of the process
3835 : * @sig: signal to send
3836 : * @info: signal info
3837 : * @flags: future flags
3838 : *
3839 : * The syscall currently only signals via PIDTYPE_PID which covers
3840 : * kill(<positive-pid>, <signal>. It does not signal threads or process
3841 : * groups.
3842 : * In order to extend the syscall to threads and process groups the @flags
3843 : * argument should be used. In essence, the @flags argument will determine
3844 : * what is signaled and not the file descriptor itself. Put in other words,
3845 : * grouping is a property of the flags argument not a property of the file
3846 : * descriptor.
3847 : *
3848 : * Return: 0 on success, negative errno on failure
3849 : */
3850 0 : SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3851 : siginfo_t __user *, info, unsigned int, flags)
3852 : {
3853 : int ret;
3854 : struct fd f;
3855 : struct pid *pid;
3856 : kernel_siginfo_t kinfo;
3857 :
3858 : /* Enforce flags be set to 0 until we add an extension. */
3859 0 : if (flags)
3860 : return -EINVAL;
3861 :
3862 0 : f = fdget(pidfd);
3863 0 : if (!f.file)
3864 : return -EBADF;
3865 :
3866 : /* Is this a pidfd? */
3867 0 : pid = pidfd_to_pid(f.file);
3868 0 : if (IS_ERR(pid)) {
3869 0 : ret = PTR_ERR(pid);
3870 0 : goto err;
3871 : }
3872 :
3873 0 : ret = -EINVAL;
3874 0 : if (!access_pidfd_pidns(pid))
3875 : goto err;
3876 :
3877 0 : if (info) {
3878 0 : ret = copy_siginfo_from_user_any(&kinfo, info);
3879 0 : if (unlikely(ret))
3880 : goto err;
3881 :
3882 0 : ret = -EINVAL;
3883 0 : if (unlikely(sig != kinfo.si_signo))
3884 : goto err;
3885 :
3886 : /* Only allow sending arbitrary signals to yourself. */
3887 0 : ret = -EPERM;
3888 0 : if ((task_pid(current) != pid) &&
3889 0 : (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3890 : goto err;
3891 : } else {
3892 0 : prepare_kill_siginfo(sig, &kinfo);
3893 : }
3894 :
3895 0 : ret = kill_pid_info(sig, &kinfo, pid);
3896 :
3897 : err:
3898 0 : fdput(f);
3899 0 : return ret;
3900 : }
3901 :
3902 : static int
3903 0 : do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3904 : {
3905 : struct task_struct *p;
3906 0 : int error = -ESRCH;
3907 :
3908 : rcu_read_lock();
3909 0 : p = find_task_by_vpid(pid);
3910 0 : if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3911 0 : error = check_kill_permission(sig, info, p);
3912 : /*
3913 : * The null signal is a permissions and process existence
3914 : * probe. No signal is actually delivered.
3915 : */
3916 0 : if (!error && sig) {
3917 0 : error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3918 : /*
3919 : * If lock_task_sighand() failed we pretend the task
3920 : * dies after receiving the signal. The window is tiny,
3921 : * and the signal is private anyway.
3922 : */
3923 0 : if (unlikely(error == -ESRCH))
3924 0 : error = 0;
3925 : }
3926 : }
3927 : rcu_read_unlock();
3928 :
3929 0 : return error;
3930 : }
3931 :
3932 0 : static int do_tkill(pid_t tgid, pid_t pid, int sig)
3933 : {
3934 : struct kernel_siginfo info;
3935 :
3936 0 : clear_siginfo(&info);
3937 0 : info.si_signo = sig;
3938 0 : info.si_errno = 0;
3939 0 : info.si_code = SI_TKILL;
3940 0 : info.si_pid = task_tgid_vnr(current);
3941 0 : info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3942 :
3943 0 : return do_send_specific(tgid, pid, sig, &info);
3944 : }
3945 :
3946 : /**
3947 : * sys_tgkill - send signal to one specific thread
3948 : * @tgid: the thread group ID of the thread
3949 : * @pid: the PID of the thread
3950 : * @sig: signal to be sent
3951 : *
3952 : * This syscall also checks the @tgid and returns -ESRCH even if the PID
3953 : * exists but it's not belonging to the target process anymore. This
3954 : * method solves the problem of threads exiting and PIDs getting reused.
3955 : */
3956 0 : SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3957 : {
3958 : /* This is only valid for single tasks */
3959 0 : if (pid <= 0 || tgid <= 0)
3960 : return -EINVAL;
3961 :
3962 0 : return do_tkill(tgid, pid, sig);
3963 : }
3964 :
3965 : /**
3966 : * sys_tkill - send signal to one specific task
3967 : * @pid: the PID of the task
3968 : * @sig: signal to be sent
3969 : *
3970 : * Send a signal to only one task, even if it's a CLONE_THREAD task.
3971 : */
3972 0 : SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3973 : {
3974 : /* This is only valid for single tasks */
3975 0 : if (pid <= 0)
3976 : return -EINVAL;
3977 :
3978 0 : return do_tkill(0, pid, sig);
3979 : }
3980 :
3981 0 : static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
3982 : {
3983 : /* Not even root can pretend to send signals from the kernel.
3984 : * Nor can they impersonate a kill()/tgkill(), which adds source info.
3985 : */
3986 0 : if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3987 0 : (task_pid_vnr(current) != pid))
3988 : return -EPERM;
3989 :
3990 : /* POSIX.1b doesn't mention process groups. */
3991 0 : return kill_proc_info(sig, info, pid);
3992 : }
3993 :
3994 : /**
3995 : * sys_rt_sigqueueinfo - send signal information to a signal
3996 : * @pid: the PID of the thread
3997 : * @sig: signal to be sent
3998 : * @uinfo: signal info to be sent
3999 : */
4000 0 : SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4001 : siginfo_t __user *, uinfo)
4002 : {
4003 : kernel_siginfo_t info;
4004 0 : int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4005 0 : if (unlikely(ret))
4006 0 : return ret;
4007 0 : return do_rt_sigqueueinfo(pid, sig, &info);
4008 : }
4009 :
4010 : #ifdef CONFIG_COMPAT
4011 : COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4012 : compat_pid_t, pid,
4013 : int, sig,
4014 : struct compat_siginfo __user *, uinfo)
4015 : {
4016 : kernel_siginfo_t info;
4017 : int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4018 : if (unlikely(ret))
4019 : return ret;
4020 : return do_rt_sigqueueinfo(pid, sig, &info);
4021 : }
4022 : #endif
4023 :
4024 0 : static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4025 : {
4026 : /* This is only valid for single tasks */
4027 0 : if (pid <= 0 || tgid <= 0)
4028 : return -EINVAL;
4029 :
4030 : /* Not even root can pretend to send signals from the kernel.
4031 : * Nor can they impersonate a kill()/tgkill(), which adds source info.
4032 : */
4033 0 : if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4034 0 : (task_pid_vnr(current) != pid))
4035 : return -EPERM;
4036 :
4037 0 : return do_send_specific(tgid, pid, sig, info);
4038 : }
4039 :
4040 0 : SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4041 : siginfo_t __user *, uinfo)
4042 : {
4043 : kernel_siginfo_t info;
4044 0 : int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4045 0 : if (unlikely(ret))
4046 0 : return ret;
4047 0 : return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4048 : }
4049 :
4050 : #ifdef CONFIG_COMPAT
4051 : COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4052 : compat_pid_t, tgid,
4053 : compat_pid_t, pid,
4054 : int, sig,
4055 : struct compat_siginfo __user *, uinfo)
4056 : {
4057 : kernel_siginfo_t info;
4058 : int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4059 : if (unlikely(ret))
4060 : return ret;
4061 : return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4062 : }
4063 : #endif
4064 :
4065 : /*
4066 : * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4067 : */
4068 0 : void kernel_sigaction(int sig, __sighandler_t action)
4069 : {
4070 0 : spin_lock_irq(¤t->sighand->siglock);
4071 0 : current->sighand->action[sig - 1].sa.sa_handler = action;
4072 0 : if (action == SIG_IGN) {
4073 : sigset_t mask;
4074 :
4075 0 : sigemptyset(&mask);
4076 0 : sigaddset(&mask, sig);
4077 :
4078 0 : flush_sigqueue_mask(&mask, ¤t->signal->shared_pending);
4079 0 : flush_sigqueue_mask(&mask, ¤t->pending);
4080 0 : recalc_sigpending();
4081 : }
4082 0 : spin_unlock_irq(¤t->sighand->siglock);
4083 0 : }
4084 : EXPORT_SYMBOL(kernel_sigaction);
4085 :
4086 0 : void __weak sigaction_compat_abi(struct k_sigaction *act,
4087 : struct k_sigaction *oact)
4088 : {
4089 0 : }
4090 :
4091 0 : int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4092 : {
4093 0 : struct task_struct *p = current, *t;
4094 : struct k_sigaction *k;
4095 : sigset_t mask;
4096 :
4097 0 : if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4098 : return -EINVAL;
4099 :
4100 0 : k = &p->sighand->action[sig-1];
4101 :
4102 0 : spin_lock_irq(&p->sighand->siglock);
4103 0 : if (k->sa.sa_flags & SA_IMMUTABLE) {
4104 0 : spin_unlock_irq(&p->sighand->siglock);
4105 0 : return -EINVAL;
4106 : }
4107 0 : if (oact)
4108 0 : *oact = *k;
4109 :
4110 : /*
4111 : * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4112 : * e.g. by having an architecture use the bit in their uapi.
4113 : */
4114 : BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4115 :
4116 : /*
4117 : * Clear unknown flag bits in order to allow userspace to detect missing
4118 : * support for flag bits and to allow the kernel to use non-uapi bits
4119 : * internally.
4120 : */
4121 0 : if (act)
4122 0 : act->sa.sa_flags &= UAPI_SA_FLAGS;
4123 0 : if (oact)
4124 0 : oact->sa.sa_flags &= UAPI_SA_FLAGS;
4125 :
4126 0 : sigaction_compat_abi(act, oact);
4127 :
4128 0 : if (act) {
4129 0 : sigdelsetmask(&act->sa.sa_mask,
4130 : sigmask(SIGKILL) | sigmask(SIGSTOP));
4131 0 : *k = *act;
4132 : /*
4133 : * POSIX 3.3.1.3:
4134 : * "Setting a signal action to SIG_IGN for a signal that is
4135 : * pending shall cause the pending signal to be discarded,
4136 : * whether or not it is blocked."
4137 : *
4138 : * "Setting a signal action to SIG_DFL for a signal that is
4139 : * pending and whose default action is to ignore the signal
4140 : * (for example, SIGCHLD), shall cause the pending signal to
4141 : * be discarded, whether or not it is blocked"
4142 : */
4143 0 : if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4144 0 : sigemptyset(&mask);
4145 0 : sigaddset(&mask, sig);
4146 0 : flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4147 0 : for_each_thread(p, t)
4148 0 : flush_sigqueue_mask(&mask, &t->pending);
4149 : }
4150 : }
4151 :
4152 0 : spin_unlock_irq(&p->sighand->siglock);
4153 0 : return 0;
4154 : }
4155 :
4156 : #ifdef CONFIG_DYNAMIC_SIGFRAME
4157 : static inline void sigaltstack_lock(void)
4158 : __acquires(¤t->sighand->siglock)
4159 : {
4160 : spin_lock_irq(¤t->sighand->siglock);
4161 : }
4162 :
4163 : static inline void sigaltstack_unlock(void)
4164 : __releases(¤t->sighand->siglock)
4165 : {
4166 : spin_unlock_irq(¤t->sighand->siglock);
4167 : }
4168 : #else
4169 : static inline void sigaltstack_lock(void) { }
4170 : static inline void sigaltstack_unlock(void) { }
4171 : #endif
4172 :
4173 : static int
4174 0 : do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4175 : size_t min_ss_size)
4176 : {
4177 0 : struct task_struct *t = current;
4178 0 : int ret = 0;
4179 :
4180 0 : if (oss) {
4181 0 : memset(oss, 0, sizeof(stack_t));
4182 0 : oss->ss_sp = (void __user *) t->sas_ss_sp;
4183 0 : oss->ss_size = t->sas_ss_size;
4184 0 : oss->ss_flags = sas_ss_flags(sp) |
4185 0 : (current->sas_ss_flags & SS_FLAG_BITS);
4186 : }
4187 :
4188 0 : if (ss) {
4189 0 : void __user *ss_sp = ss->ss_sp;
4190 0 : size_t ss_size = ss->ss_size;
4191 0 : unsigned ss_flags = ss->ss_flags;
4192 : int ss_mode;
4193 :
4194 0 : if (unlikely(on_sig_stack(sp)))
4195 : return -EPERM;
4196 :
4197 0 : ss_mode = ss_flags & ~SS_FLAG_BITS;
4198 0 : if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4199 : ss_mode != 0))
4200 : return -EINVAL;
4201 :
4202 : /*
4203 : * Return before taking any locks if no actual
4204 : * sigaltstack changes were requested.
4205 : */
4206 0 : if (t->sas_ss_sp == (unsigned long)ss_sp &&
4207 0 : t->sas_ss_size == ss_size &&
4208 0 : t->sas_ss_flags == ss_flags)
4209 : return 0;
4210 :
4211 : sigaltstack_lock();
4212 0 : if (ss_mode == SS_DISABLE) {
4213 : ss_size = 0;
4214 : ss_sp = NULL;
4215 : } else {
4216 0 : if (unlikely(ss_size < min_ss_size))
4217 0 : ret = -ENOMEM;
4218 : if (!sigaltstack_size_valid(ss_size))
4219 : ret = -ENOMEM;
4220 : }
4221 0 : if (!ret) {
4222 0 : t->sas_ss_sp = (unsigned long) ss_sp;
4223 0 : t->sas_ss_size = ss_size;
4224 0 : t->sas_ss_flags = ss_flags;
4225 : }
4226 : sigaltstack_unlock();
4227 : }
4228 : return ret;
4229 : }
4230 :
4231 0 : SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4232 : {
4233 : stack_t new, old;
4234 : int err;
4235 0 : if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4236 : return -EFAULT;
4237 0 : err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4238 0 : current_user_stack_pointer(),
4239 : MINSIGSTKSZ);
4240 0 : if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4241 0 : err = -EFAULT;
4242 0 : return err;
4243 : }
4244 :
4245 0 : int restore_altstack(const stack_t __user *uss)
4246 : {
4247 : stack_t new;
4248 0 : if (copy_from_user(&new, uss, sizeof(stack_t)))
4249 : return -EFAULT;
4250 0 : (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4251 : MINSIGSTKSZ);
4252 : /* squash all but EFAULT for now */
4253 0 : return 0;
4254 : }
4255 :
4256 0 : int __save_altstack(stack_t __user *uss, unsigned long sp)
4257 : {
4258 0 : struct task_struct *t = current;
4259 0 : int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4260 0 : __put_user(t->sas_ss_flags, &uss->ss_flags) |
4261 0 : __put_user(t->sas_ss_size, &uss->ss_size);
4262 0 : return err;
4263 : }
4264 :
4265 : #ifdef CONFIG_COMPAT
4266 : static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4267 : compat_stack_t __user *uoss_ptr)
4268 : {
4269 : stack_t uss, uoss;
4270 : int ret;
4271 :
4272 : if (uss_ptr) {
4273 : compat_stack_t uss32;
4274 : if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4275 : return -EFAULT;
4276 : uss.ss_sp = compat_ptr(uss32.ss_sp);
4277 : uss.ss_flags = uss32.ss_flags;
4278 : uss.ss_size = uss32.ss_size;
4279 : }
4280 : ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4281 : compat_user_stack_pointer(),
4282 : COMPAT_MINSIGSTKSZ);
4283 : if (ret >= 0 && uoss_ptr) {
4284 : compat_stack_t old;
4285 : memset(&old, 0, sizeof(old));
4286 : old.ss_sp = ptr_to_compat(uoss.ss_sp);
4287 : old.ss_flags = uoss.ss_flags;
4288 : old.ss_size = uoss.ss_size;
4289 : if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4290 : ret = -EFAULT;
4291 : }
4292 : return ret;
4293 : }
4294 :
4295 : COMPAT_SYSCALL_DEFINE2(sigaltstack,
4296 : const compat_stack_t __user *, uss_ptr,
4297 : compat_stack_t __user *, uoss_ptr)
4298 : {
4299 : return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4300 : }
4301 :
4302 : int compat_restore_altstack(const compat_stack_t __user *uss)
4303 : {
4304 : int err = do_compat_sigaltstack(uss, NULL);
4305 : /* squash all but -EFAULT for now */
4306 : return err == -EFAULT ? err : 0;
4307 : }
4308 :
4309 : int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4310 : {
4311 : int err;
4312 : struct task_struct *t = current;
4313 : err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4314 : &uss->ss_sp) |
4315 : __put_user(t->sas_ss_flags, &uss->ss_flags) |
4316 : __put_user(t->sas_ss_size, &uss->ss_size);
4317 : return err;
4318 : }
4319 : #endif
4320 :
4321 : #ifdef __ARCH_WANT_SYS_SIGPENDING
4322 :
4323 : /**
4324 : * sys_sigpending - examine pending signals
4325 : * @uset: where mask of pending signal is returned
4326 : */
4327 0 : SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4328 : {
4329 : sigset_t set;
4330 :
4331 : if (sizeof(old_sigset_t) > sizeof(*uset))
4332 : return -EINVAL;
4333 :
4334 0 : do_sigpending(&set);
4335 :
4336 0 : if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4337 : return -EFAULT;
4338 :
4339 0 : return 0;
4340 : }
4341 :
4342 : #ifdef CONFIG_COMPAT
4343 : COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4344 : {
4345 : sigset_t set;
4346 :
4347 : do_sigpending(&set);
4348 :
4349 : return put_user(set.sig[0], set32);
4350 : }
4351 : #endif
4352 :
4353 : #endif
4354 :
4355 : #ifdef __ARCH_WANT_SYS_SIGPROCMASK
4356 : /**
4357 : * sys_sigprocmask - examine and change blocked signals
4358 : * @how: whether to add, remove, or set signals
4359 : * @nset: signals to add or remove (if non-null)
4360 : * @oset: previous value of signal mask if non-null
4361 : *
4362 : * Some platforms have their own version with special arguments;
4363 : * others support only sys_rt_sigprocmask.
4364 : */
4365 :
4366 0 : SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4367 : old_sigset_t __user *, oset)
4368 : {
4369 : old_sigset_t old_set, new_set;
4370 : sigset_t new_blocked;
4371 :
4372 0 : old_set = current->blocked.sig[0];
4373 :
4374 0 : if (nset) {
4375 0 : if (copy_from_user(&new_set, nset, sizeof(*nset)))
4376 : return -EFAULT;
4377 :
4378 0 : new_blocked = current->blocked;
4379 :
4380 0 : switch (how) {
4381 : case SIG_BLOCK:
4382 0 : sigaddsetmask(&new_blocked, new_set);
4383 : break;
4384 : case SIG_UNBLOCK:
4385 0 : sigdelsetmask(&new_blocked, new_set);
4386 : break;
4387 : case SIG_SETMASK:
4388 0 : new_blocked.sig[0] = new_set;
4389 0 : break;
4390 : default:
4391 : return -EINVAL;
4392 : }
4393 :
4394 : set_current_blocked(&new_blocked);
4395 : }
4396 :
4397 0 : if (oset) {
4398 0 : if (copy_to_user(oset, &old_set, sizeof(*oset)))
4399 : return -EFAULT;
4400 : }
4401 :
4402 : return 0;
4403 : }
4404 : #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4405 :
4406 : #ifndef CONFIG_ODD_RT_SIGACTION
4407 : /**
4408 : * sys_rt_sigaction - alter an action taken by a process
4409 : * @sig: signal to be sent
4410 : * @act: new sigaction
4411 : * @oact: used to save the previous sigaction
4412 : * @sigsetsize: size of sigset_t type
4413 : */
4414 0 : SYSCALL_DEFINE4(rt_sigaction, int, sig,
4415 : const struct sigaction __user *, act,
4416 : struct sigaction __user *, oact,
4417 : size_t, sigsetsize)
4418 : {
4419 : struct k_sigaction new_sa, old_sa;
4420 : int ret;
4421 :
4422 : /* XXX: Don't preclude handling different sized sigset_t's. */
4423 0 : if (sigsetsize != sizeof(sigset_t))
4424 : return -EINVAL;
4425 :
4426 0 : if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4427 : return -EFAULT;
4428 :
4429 0 : ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4430 0 : if (ret)
4431 0 : return ret;
4432 :
4433 0 : if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4434 : return -EFAULT;
4435 :
4436 : return 0;
4437 : }
4438 : #ifdef CONFIG_COMPAT
4439 : COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4440 : const struct compat_sigaction __user *, act,
4441 : struct compat_sigaction __user *, oact,
4442 : compat_size_t, sigsetsize)
4443 : {
4444 : struct k_sigaction new_ka, old_ka;
4445 : #ifdef __ARCH_HAS_SA_RESTORER
4446 : compat_uptr_t restorer;
4447 : #endif
4448 : int ret;
4449 :
4450 : /* XXX: Don't preclude handling different sized sigset_t's. */
4451 : if (sigsetsize != sizeof(compat_sigset_t))
4452 : return -EINVAL;
4453 :
4454 : if (act) {
4455 : compat_uptr_t handler;
4456 : ret = get_user(handler, &act->sa_handler);
4457 : new_ka.sa.sa_handler = compat_ptr(handler);
4458 : #ifdef __ARCH_HAS_SA_RESTORER
4459 : ret |= get_user(restorer, &act->sa_restorer);
4460 : new_ka.sa.sa_restorer = compat_ptr(restorer);
4461 : #endif
4462 : ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4463 : ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4464 : if (ret)
4465 : return -EFAULT;
4466 : }
4467 :
4468 : ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4469 : if (!ret && oact) {
4470 : ret = put_user(ptr_to_compat(old_ka.sa.sa_handler),
4471 : &oact->sa_handler);
4472 : ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4473 : sizeof(oact->sa_mask));
4474 : ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4475 : #ifdef __ARCH_HAS_SA_RESTORER
4476 : ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4477 : &oact->sa_restorer);
4478 : #endif
4479 : }
4480 : return ret;
4481 : }
4482 : #endif
4483 : #endif /* !CONFIG_ODD_RT_SIGACTION */
4484 :
4485 : #ifdef CONFIG_OLD_SIGACTION
4486 : SYSCALL_DEFINE3(sigaction, int, sig,
4487 : const struct old_sigaction __user *, act,
4488 : struct old_sigaction __user *, oact)
4489 : {
4490 : struct k_sigaction new_ka, old_ka;
4491 : int ret;
4492 :
4493 : if (act) {
4494 : old_sigset_t mask;
4495 : if (!access_ok(act, sizeof(*act)) ||
4496 : __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4497 : __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4498 : __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4499 : __get_user(mask, &act->sa_mask))
4500 : return -EFAULT;
4501 : #ifdef __ARCH_HAS_KA_RESTORER
4502 : new_ka.ka_restorer = NULL;
4503 : #endif
4504 : siginitset(&new_ka.sa.sa_mask, mask);
4505 : }
4506 :
4507 : ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4508 :
4509 : if (!ret && oact) {
4510 : if (!access_ok(oact, sizeof(*oact)) ||
4511 : __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4512 : __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4513 : __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4514 : __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4515 : return -EFAULT;
4516 : }
4517 :
4518 : return ret;
4519 : }
4520 : #endif
4521 : #ifdef CONFIG_COMPAT_OLD_SIGACTION
4522 : COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4523 : const struct compat_old_sigaction __user *, act,
4524 : struct compat_old_sigaction __user *, oact)
4525 : {
4526 : struct k_sigaction new_ka, old_ka;
4527 : int ret;
4528 : compat_old_sigset_t mask;
4529 : compat_uptr_t handler, restorer;
4530 :
4531 : if (act) {
4532 : if (!access_ok(act, sizeof(*act)) ||
4533 : __get_user(handler, &act->sa_handler) ||
4534 : __get_user(restorer, &act->sa_restorer) ||
4535 : __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4536 : __get_user(mask, &act->sa_mask))
4537 : return -EFAULT;
4538 :
4539 : #ifdef __ARCH_HAS_KA_RESTORER
4540 : new_ka.ka_restorer = NULL;
4541 : #endif
4542 : new_ka.sa.sa_handler = compat_ptr(handler);
4543 : new_ka.sa.sa_restorer = compat_ptr(restorer);
4544 : siginitset(&new_ka.sa.sa_mask, mask);
4545 : }
4546 :
4547 : ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4548 :
4549 : if (!ret && oact) {
4550 : if (!access_ok(oact, sizeof(*oact)) ||
4551 : __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4552 : &oact->sa_handler) ||
4553 : __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4554 : &oact->sa_restorer) ||
4555 : __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4556 : __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4557 : return -EFAULT;
4558 : }
4559 : return ret;
4560 : }
4561 : #endif
4562 :
4563 : #ifdef CONFIG_SGETMASK_SYSCALL
4564 :
4565 : /*
4566 : * For backwards compatibility. Functionality superseded by sigprocmask.
4567 : */
4568 : SYSCALL_DEFINE0(sgetmask)
4569 : {
4570 : /* SMP safe */
4571 : return current->blocked.sig[0];
4572 : }
4573 :
4574 : SYSCALL_DEFINE1(ssetmask, int, newmask)
4575 : {
4576 : int old = current->blocked.sig[0];
4577 : sigset_t newset;
4578 :
4579 : siginitset(&newset, newmask);
4580 : set_current_blocked(&newset);
4581 :
4582 : return old;
4583 : }
4584 : #endif /* CONFIG_SGETMASK_SYSCALL */
4585 :
4586 : #ifdef __ARCH_WANT_SYS_SIGNAL
4587 : /*
4588 : * For backwards compatibility. Functionality superseded by sigaction.
4589 : */
4590 0 : SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4591 : {
4592 : struct k_sigaction new_sa, old_sa;
4593 : int ret;
4594 :
4595 0 : new_sa.sa.sa_handler = handler;
4596 0 : new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4597 0 : sigemptyset(&new_sa.sa.sa_mask);
4598 :
4599 0 : ret = do_sigaction(sig, &new_sa, &old_sa);
4600 :
4601 0 : return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4602 : }
4603 : #endif /* __ARCH_WANT_SYS_SIGNAL */
4604 :
4605 : #ifdef __ARCH_WANT_SYS_PAUSE
4606 :
4607 0 : SYSCALL_DEFINE0(pause)
4608 : {
4609 0 : while (!signal_pending(current)) {
4610 0 : __set_current_state(TASK_INTERRUPTIBLE);
4611 0 : schedule();
4612 : }
4613 0 : return -ERESTARTNOHAND;
4614 : }
4615 :
4616 : #endif
4617 :
4618 0 : static int sigsuspend(sigset_t *set)
4619 : {
4620 0 : current->saved_sigmask = current->blocked;
4621 : set_current_blocked(set);
4622 :
4623 0 : while (!signal_pending(current)) {
4624 0 : __set_current_state(TASK_INTERRUPTIBLE);
4625 0 : schedule();
4626 : }
4627 0 : set_restore_sigmask();
4628 0 : return -ERESTARTNOHAND;
4629 : }
4630 :
4631 : /**
4632 : * sys_rt_sigsuspend - replace the signal mask for a value with the
4633 : * @unewset value until a signal is received
4634 : * @unewset: new signal mask value
4635 : * @sigsetsize: size of sigset_t type
4636 : */
4637 0 : SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4638 : {
4639 : sigset_t newset;
4640 :
4641 : /* XXX: Don't preclude handling different sized sigset_t's. */
4642 0 : if (sigsetsize != sizeof(sigset_t))
4643 : return -EINVAL;
4644 :
4645 0 : if (copy_from_user(&newset, unewset, sizeof(newset)))
4646 : return -EFAULT;
4647 0 : return sigsuspend(&newset);
4648 : }
4649 :
4650 : #ifdef CONFIG_COMPAT
4651 : COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4652 : {
4653 : sigset_t newset;
4654 :
4655 : /* XXX: Don't preclude handling different sized sigset_t's. */
4656 : if (sigsetsize != sizeof(sigset_t))
4657 : return -EINVAL;
4658 :
4659 : if (get_compat_sigset(&newset, unewset))
4660 : return -EFAULT;
4661 : return sigsuspend(&newset);
4662 : }
4663 : #endif
4664 :
4665 : #ifdef CONFIG_OLD_SIGSUSPEND
4666 : SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4667 : {
4668 : sigset_t blocked;
4669 : siginitset(&blocked, mask);
4670 : return sigsuspend(&blocked);
4671 : }
4672 : #endif
4673 : #ifdef CONFIG_OLD_SIGSUSPEND3
4674 : SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4675 : {
4676 : sigset_t blocked;
4677 : siginitset(&blocked, mask);
4678 : return sigsuspend(&blocked);
4679 : }
4680 : #endif
4681 :
4682 0 : __weak const char *arch_vma_name(struct vm_area_struct *vma)
4683 : {
4684 0 : return NULL;
4685 : }
4686 :
4687 : static inline void siginfo_buildtime_checks(void)
4688 : {
4689 : BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4690 :
4691 : /* Verify the offsets in the two siginfos match */
4692 : #define CHECK_OFFSET(field) \
4693 : BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4694 :
4695 : /* kill */
4696 : CHECK_OFFSET(si_pid);
4697 : CHECK_OFFSET(si_uid);
4698 :
4699 : /* timer */
4700 : CHECK_OFFSET(si_tid);
4701 : CHECK_OFFSET(si_overrun);
4702 : CHECK_OFFSET(si_value);
4703 :
4704 : /* rt */
4705 : CHECK_OFFSET(si_pid);
4706 : CHECK_OFFSET(si_uid);
4707 : CHECK_OFFSET(si_value);
4708 :
4709 : /* sigchld */
4710 : CHECK_OFFSET(si_pid);
4711 : CHECK_OFFSET(si_uid);
4712 : CHECK_OFFSET(si_status);
4713 : CHECK_OFFSET(si_utime);
4714 : CHECK_OFFSET(si_stime);
4715 :
4716 : /* sigfault */
4717 : CHECK_OFFSET(si_addr);
4718 : CHECK_OFFSET(si_trapno);
4719 : CHECK_OFFSET(si_addr_lsb);
4720 : CHECK_OFFSET(si_lower);
4721 : CHECK_OFFSET(si_upper);
4722 : CHECK_OFFSET(si_pkey);
4723 : CHECK_OFFSET(si_perf_data);
4724 : CHECK_OFFSET(si_perf_type);
4725 :
4726 : /* sigpoll */
4727 : CHECK_OFFSET(si_band);
4728 : CHECK_OFFSET(si_fd);
4729 :
4730 : /* sigsys */
4731 : CHECK_OFFSET(si_call_addr);
4732 : CHECK_OFFSET(si_syscall);
4733 : CHECK_OFFSET(si_arch);
4734 : #undef CHECK_OFFSET
4735 :
4736 : /* usb asyncio */
4737 : BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4738 : offsetof(struct siginfo, si_addr));
4739 : if (sizeof(int) == sizeof(void __user *)) {
4740 : BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4741 : sizeof(void __user *));
4742 : } else {
4743 : BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4744 : sizeof_field(struct siginfo, si_uid)) !=
4745 : sizeof(void __user *));
4746 : BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4747 : offsetof(struct siginfo, si_uid));
4748 : }
4749 : #ifdef CONFIG_COMPAT
4750 : BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4751 : offsetof(struct compat_siginfo, si_addr));
4752 : BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4753 : sizeof(compat_uptr_t));
4754 : BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4755 : sizeof_field(struct siginfo, si_pid));
4756 : #endif
4757 : }
4758 :
4759 1 : void __init signals_init(void)
4760 : {
4761 : siginfo_buildtime_checks();
4762 :
4763 1 : sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4764 1 : }
4765 :
4766 : #ifdef CONFIG_KGDB_KDB
4767 : #include <linux/kdb.h>
4768 : /*
4769 : * kdb_send_sig - Allows kdb to send signals without exposing
4770 : * signal internals. This function checks if the required locks are
4771 : * available before calling the main signal code, to avoid kdb
4772 : * deadlocks.
4773 : */
4774 : void kdb_send_sig(struct task_struct *t, int sig)
4775 : {
4776 : static struct task_struct *kdb_prev_t;
4777 : int new_t, ret;
4778 : if (!spin_trylock(&t->sighand->siglock)) {
4779 : kdb_printf("Can't do kill command now.\n"
4780 : "The sigmask lock is held somewhere else in "
4781 : "kernel, try again later\n");
4782 : return;
4783 : }
4784 : new_t = kdb_prev_t != t;
4785 : kdb_prev_t = t;
4786 : if (!task_is_running(t) && new_t) {
4787 : spin_unlock(&t->sighand->siglock);
4788 : kdb_printf("Process is not RUNNING, sending a signal from "
4789 : "kdb risks deadlock\n"
4790 : "on the run queue locks. "
4791 : "The signal has _not_ been sent.\n"
4792 : "Reissue the kill command if you want to risk "
4793 : "the deadlock.\n");
4794 : return;
4795 : }
4796 : ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4797 : spin_unlock(&t->sighand->siglock);
4798 : if (ret)
4799 : kdb_printf("Fail to deliver Signal %d to process %d.\n",
4800 : sig, t->pid);
4801 : else
4802 : kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4803 : }
4804 : #endif /* CONFIG_KGDB_KDB */
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