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Source at commit be977234bfb4a6dca8a39e7c52165e4cd536ad71 created 12 years 9 months ago. By Lars-Peter Clausen, jz4740: Fix compile error | |
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1 | /* |
2 | * linux/kernel/signal.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | * |
6 | * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson |
7 | * |
8 | * 2003-06-02 Jim Houston - Concurrent Computer Corp. |
9 | * Changes to use preallocated sigqueue structures |
10 | * to allow signals to be sent reliably. |
11 | */ |
12 | |
13 | #include <linux/slab.h> |
14 | #include <linux/module.h> |
15 | #include <linux/init.h> |
16 | #include <linux/sched.h> |
17 | #include <linux/fs.h> |
18 | #include <linux/tty.h> |
19 | #include <linux/binfmts.h> |
20 | #include <linux/security.h> |
21 | #include <linux/syscalls.h> |
22 | #include <linux/ptrace.h> |
23 | #include <linux/signal.h> |
24 | #include <linux/signalfd.h> |
25 | #include <linux/ratelimit.h> |
26 | #include <linux/tracehook.h> |
27 | #include <linux/capability.h> |
28 | #include <linux/freezer.h> |
29 | #include <linux/pid_namespace.h> |
30 | #include <linux/nsproxy.h> |
31 | #define CREATE_TRACE_POINTS |
32 | #include <trace/events/signal.h> |
33 | |
34 | #include <asm/param.h> |
35 | #include <asm/uaccess.h> |
36 | #include <asm/unistd.h> |
37 | #include <asm/siginfo.h> |
38 | #include "audit.h" /* audit_signal_info() */ |
39 | |
40 | /* |
41 | * SLAB caches for signal bits. |
42 | */ |
43 | |
44 | static struct kmem_cache *sigqueue_cachep; |
45 | |
46 | int print_fatal_signals __read_mostly; |
47 | |
48 | static void __user *sig_handler(struct task_struct *t, int sig) |
49 | { |
50 | return t->sighand->action[sig - 1].sa.sa_handler; |
51 | } |
52 | |
53 | static int sig_handler_ignored(void __user *handler, int sig) |
54 | { |
55 | /* Is it explicitly or implicitly ignored? */ |
56 | return handler == SIG_IGN || |
57 | (handler == SIG_DFL && sig_kernel_ignore(sig)); |
58 | } |
59 | |
60 | static int sig_task_ignored(struct task_struct *t, int sig, |
61 | int from_ancestor_ns) |
62 | { |
63 | void __user *handler; |
64 | |
65 | handler = sig_handler(t, sig); |
66 | |
67 | if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && |
68 | handler == SIG_DFL && !from_ancestor_ns) |
69 | return 1; |
70 | |
71 | return sig_handler_ignored(handler, sig); |
72 | } |
73 | |
74 | static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns) |
75 | { |
76 | /* |
77 | * Blocked signals are never ignored, since the |
78 | * signal handler may change by the time it is |
79 | * unblocked. |
80 | */ |
81 | if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) |
82 | return 0; |
83 | |
84 | if (!sig_task_ignored(t, sig, from_ancestor_ns)) |
85 | return 0; |
86 | |
87 | /* |
88 | * Tracers may want to know about even ignored signals. |
89 | */ |
90 | return !tracehook_consider_ignored_signal(t, sig); |
91 | } |
92 | |
93 | /* |
94 | * Re-calculate pending state from the set of locally pending |
95 | * signals, globally pending signals, and blocked signals. |
96 | */ |
97 | static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked) |
98 | { |
99 | unsigned long ready; |
100 | long i; |
101 | |
102 | switch (_NSIG_WORDS) { |
103 | default: |
104 | for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;) |
105 | ready |= signal->sig[i] &~ blocked->sig[i]; |
106 | break; |
107 | |
108 | case 4: ready = signal->sig[3] &~ blocked->sig[3]; |
109 | ready |= signal->sig[2] &~ blocked->sig[2]; |
110 | ready |= signal->sig[1] &~ blocked->sig[1]; |
111 | ready |= signal->sig[0] &~ blocked->sig[0]; |
112 | break; |
113 | |
114 | case 2: ready = signal->sig[1] &~ blocked->sig[1]; |
115 | ready |= signal->sig[0] &~ blocked->sig[0]; |
116 | break; |
117 | |
118 | case 1: ready = signal->sig[0] &~ blocked->sig[0]; |
119 | } |
120 | return ready != 0; |
121 | } |
122 | |
123 | #define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) |
124 | |
125 | static int recalc_sigpending_tsk(struct task_struct *t) |
126 | { |
127 | if (t->signal->group_stop_count > 0 || |
128 | PENDING(&t->pending, &t->blocked) || |
129 | PENDING(&t->signal->shared_pending, &t->blocked)) { |
130 | set_tsk_thread_flag(t, TIF_SIGPENDING); |
131 | return 1; |
132 | } |
133 | /* |
134 | * We must never clear the flag in another thread, or in current |
135 | * when it's possible the current syscall is returning -ERESTART*. |
136 | * So we don't clear it here, and only callers who know they should do. |
137 | */ |
138 | return 0; |
139 | } |
140 | |
141 | /* |
142 | * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. |
143 | * This is superfluous when called on current, the wakeup is a harmless no-op. |
144 | */ |
145 | void recalc_sigpending_and_wake(struct task_struct *t) |
146 | { |
147 | if (recalc_sigpending_tsk(t)) |
148 | signal_wake_up(t, 0); |
149 | } |
150 | |
151 | void recalc_sigpending(void) |
152 | { |
153 | if (unlikely(tracehook_force_sigpending())) |
154 | set_thread_flag(TIF_SIGPENDING); |
155 | else if (!recalc_sigpending_tsk(current) && !freezing(current)) |
156 | clear_thread_flag(TIF_SIGPENDING); |
157 | |
158 | } |
159 | |
160 | /* Given the mask, find the first available signal that should be serviced. */ |
161 | |
162 | #define SYNCHRONOUS_MASK \ |
163 | (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ |
164 | sigmask(SIGTRAP) | sigmask(SIGFPE)) |
165 | |
166 | int next_signal(struct sigpending *pending, sigset_t *mask) |
167 | { |
168 | unsigned long i, *s, *m, x; |
169 | int sig = 0; |
170 | |
171 | s = pending->signal.sig; |
172 | m = mask->sig; |
173 | |
174 | /* |
175 | * Handle the first word specially: it contains the |
176 | * synchronous signals that need to be dequeued first. |
177 | */ |
178 | x = *s &~ *m; |
179 | if (x) { |
180 | if (x & SYNCHRONOUS_MASK) |
181 | x &= SYNCHRONOUS_MASK; |
182 | sig = ffz(~x) + 1; |
183 | return sig; |
184 | } |
185 | |
186 | switch (_NSIG_WORDS) { |
187 | default: |
188 | for (i = 1; i < _NSIG_WORDS; ++i) { |
189 | x = *++s &~ *++m; |
190 | if (!x) |
191 | continue; |
192 | sig = ffz(~x) + i*_NSIG_BPW + 1; |
193 | break; |
194 | } |
195 | break; |
196 | |
197 | case 2: |
198 | x = s[1] &~ m[1]; |
199 | if (!x) |
200 | break; |
201 | sig = ffz(~x) + _NSIG_BPW + 1; |
202 | break; |
203 | |
204 | case 1: |
205 | /* Nothing to do */ |
206 | break; |
207 | } |
208 | |
209 | return sig; |
210 | } |
211 | |
212 | static inline void print_dropped_signal(int sig) |
213 | { |
214 | static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); |
215 | |
216 | if (!print_fatal_signals) |
217 | return; |
218 | |
219 | if (!__ratelimit(&ratelimit_state)) |
220 | return; |
221 | |
222 | printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", |
223 | current->comm, current->pid, sig); |
224 | } |
225 | |
226 | /* |
227 | * allocate a new signal queue record |
228 | * - this may be called without locks if and only if t == current, otherwise an |
229 | * appropriate lock must be held to stop the target task from exiting |
230 | */ |
231 | static struct sigqueue * |
232 | __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit) |
233 | { |
234 | struct sigqueue *q = NULL; |
235 | struct user_struct *user; |
236 | |
237 | /* |
238 | * Protect access to @t credentials. This can go away when all |
239 | * callers hold rcu read lock. |
240 | */ |
241 | rcu_read_lock(); |
242 | user = get_uid(__task_cred(t)->user); |
243 | atomic_inc(&user->sigpending); |
244 | rcu_read_unlock(); |
245 | |
246 | if (override_rlimit || |
247 | atomic_read(&user->sigpending) <= |
248 | task_rlimit(t, RLIMIT_SIGPENDING)) { |
249 | q = kmem_cache_alloc(sigqueue_cachep, flags); |
250 | } else { |
251 | print_dropped_signal(sig); |
252 | } |
253 | |
254 | if (unlikely(q == NULL)) { |
255 | atomic_dec(&user->sigpending); |
256 | free_uid(user); |
257 | } else { |
258 | INIT_LIST_HEAD(&q->list); |
259 | q->flags = 0; |
260 | q->user = user; |
261 | } |
262 | |
263 | return q; |
264 | } |
265 | |
266 | static void __sigqueue_free(struct sigqueue *q) |
267 | { |
268 | if (q->flags & SIGQUEUE_PREALLOC) |
269 | return; |
270 | atomic_dec(&q->user->sigpending); |
271 | free_uid(q->user); |
272 | kmem_cache_free(sigqueue_cachep, q); |
273 | } |
274 | |
275 | void flush_sigqueue(struct sigpending *queue) |
276 | { |
277 | struct sigqueue *q; |
278 | |
279 | sigemptyset(&queue->signal); |
280 | while (!list_empty(&queue->list)) { |
281 | q = list_entry(queue->list.next, struct sigqueue , list); |
282 | list_del_init(&q->list); |
283 | __sigqueue_free(q); |
284 | } |
285 | } |
286 | |
287 | /* |
288 | * Flush all pending signals for a task. |
289 | */ |
290 | void __flush_signals(struct task_struct *t) |
291 | { |
292 | clear_tsk_thread_flag(t, TIF_SIGPENDING); |
293 | flush_sigqueue(&t->pending); |
294 | flush_sigqueue(&t->signal->shared_pending); |
295 | } |
296 | |
297 | void flush_signals(struct task_struct *t) |
298 | { |
299 | unsigned long flags; |
300 | |
301 | spin_lock_irqsave(&t->sighand->siglock, flags); |
302 | __flush_signals(t); |
303 | spin_unlock_irqrestore(&t->sighand->siglock, flags); |
304 | } |
305 | |
306 | static void __flush_itimer_signals(struct sigpending *pending) |
307 | { |
308 | sigset_t signal, retain; |
309 | struct sigqueue *q, *n; |
310 | |
311 | signal = pending->signal; |
312 | sigemptyset(&retain); |
313 | |
314 | list_for_each_entry_safe(q, n, &pending->list, list) { |
315 | int sig = q->info.si_signo; |
316 | |
317 | if (likely(q->info.si_code != SI_TIMER)) { |
318 | sigaddset(&retain, sig); |
319 | } else { |
320 | sigdelset(&signal, sig); |
321 | list_del_init(&q->list); |
322 | __sigqueue_free(q); |
323 | } |
324 | } |
325 | |
326 | sigorsets(&pending->signal, &signal, &retain); |
327 | } |
328 | |
329 | void flush_itimer_signals(void) |
330 | { |
331 | struct task_struct *tsk = current; |
332 | unsigned long flags; |
333 | |
334 | spin_lock_irqsave(&tsk->sighand->siglock, flags); |
335 | __flush_itimer_signals(&tsk->pending); |
336 | __flush_itimer_signals(&tsk->signal->shared_pending); |
337 | spin_unlock_irqrestore(&tsk->sighand->siglock, flags); |
338 | } |
339 | |
340 | void ignore_signals(struct task_struct *t) |
341 | { |
342 | int i; |
343 | |
344 | for (i = 0; i < _NSIG; ++i) |
345 | t->sighand->action[i].sa.sa_handler = SIG_IGN; |
346 | |
347 | flush_signals(t); |
348 | } |
349 | |
350 | /* |
351 | * Flush all handlers for a task. |
352 | */ |
353 | |
354 | void |
355 | flush_signal_handlers(struct task_struct *t, int force_default) |
356 | { |
357 | int i; |
358 | struct k_sigaction *ka = &t->sighand->action[0]; |
359 | for (i = _NSIG ; i != 0 ; i--) { |
360 | if (force_default || ka->sa.sa_handler != SIG_IGN) |
361 | ka->sa.sa_handler = SIG_DFL; |
362 | ka->sa.sa_flags = 0; |
363 | sigemptyset(&ka->sa.sa_mask); |
364 | ka++; |
365 | } |
366 | } |
367 | |
368 | int unhandled_signal(struct task_struct *tsk, int sig) |
369 | { |
370 | void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; |
371 | if (is_global_init(tsk)) |
372 | return 1; |
373 | if (handler != SIG_IGN && handler != SIG_DFL) |
374 | return 0; |
375 | return !tracehook_consider_fatal_signal(tsk, sig); |
376 | } |
377 | |
378 | /* |
379 | * Notify the system that a driver wants to block all signals for this |
380 | * process, and wants to be notified if any signals at all were to be |
381 | * sent/acted upon. If the notifier routine returns non-zero, then the |
382 | * signal will be acted upon after all. If the notifier routine returns 0, |
383 | * then then signal will be blocked. Only one block per process is |
384 | * allowed. priv is a pointer to private data that the notifier routine |
385 | * can use to determine if the signal should be blocked or not. |
386 | */ |
387 | void |
388 | block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask) |
389 | { |
390 | unsigned long flags; |
391 | |
392 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
393 | current->notifier_mask = mask; |
394 | current->notifier_data = priv; |
395 | current->notifier = notifier; |
396 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
397 | } |
398 | |
399 | /* Notify the system that blocking has ended. */ |
400 | |
401 | void |
402 | unblock_all_signals(void) |
403 | { |
404 | unsigned long flags; |
405 | |
406 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
407 | current->notifier = NULL; |
408 | current->notifier_data = NULL; |
409 | recalc_sigpending(); |
410 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
411 | } |
412 | |
413 | static void collect_signal(int sig, struct sigpending *list, siginfo_t *info) |
414 | { |
415 | struct sigqueue *q, *first = NULL; |
416 | |
417 | /* |
418 | * Collect the siginfo appropriate to this signal. Check if |
419 | * there is another siginfo for the same signal. |
420 | */ |
421 | list_for_each_entry(q, &list->list, list) { |
422 | if (q->info.si_signo == sig) { |
423 | if (first) |
424 | goto still_pending; |
425 | first = q; |
426 | } |
427 | } |
428 | |
429 | sigdelset(&list->signal, sig); |
430 | |
431 | if (first) { |
432 | still_pending: |
433 | list_del_init(&first->list); |
434 | copy_siginfo(info, &first->info); |
435 | __sigqueue_free(first); |
436 | } else { |
437 | /* |
438 | * Ok, it wasn't in the queue. This must be |
439 | * a fast-pathed signal or we must have been |
440 | * out of queue space. So zero out the info. |
441 | */ |
442 | info->si_signo = sig; |
443 | info->si_errno = 0; |
444 | info->si_code = SI_USER; |
445 | info->si_pid = 0; |
446 | info->si_uid = 0; |
447 | } |
448 | } |
449 | |
450 | static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, |
451 | siginfo_t *info) |
452 | { |
453 | int sig = next_signal(pending, mask); |
454 | |
455 | if (sig) { |
456 | if (current->notifier) { |
457 | if (sigismember(current->notifier_mask, sig)) { |
458 | if (!(current->notifier)(current->notifier_data)) { |
459 | clear_thread_flag(TIF_SIGPENDING); |
460 | return 0; |
461 | } |
462 | } |
463 | } |
464 | |
465 | collect_signal(sig, pending, info); |
466 | } |
467 | |
468 | return sig; |
469 | } |
470 | |
471 | /* |
472 | * Dequeue a signal and return the element to the caller, which is |
473 | * expected to free it. |
474 | * |
475 | * All callers have to hold the siglock. |
476 | */ |
477 | int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) |
478 | { |
479 | int signr; |
480 | |
481 | /* We only dequeue private signals from ourselves, we don't let |
482 | * signalfd steal them |
483 | */ |
484 | signr = __dequeue_signal(&tsk->pending, mask, info); |
485 | if (!signr) { |
486 | signr = __dequeue_signal(&tsk->signal->shared_pending, |
487 | mask, info); |
488 | /* |
489 | * itimer signal ? |
490 | * |
491 | * itimers are process shared and we restart periodic |
492 | * itimers in the signal delivery path to prevent DoS |
493 | * attacks in the high resolution timer case. This is |
494 | * compliant with the old way of self-restarting |
495 | * itimers, as the SIGALRM is a legacy signal and only |
496 | * queued once. Changing the restart behaviour to |
497 | * restart the timer in the signal dequeue path is |
498 | * reducing the timer noise on heavy loaded !highres |
499 | * systems too. |
500 | */ |
501 | if (unlikely(signr == SIGALRM)) { |
502 | struct hrtimer *tmr = &tsk->signal->real_timer; |
503 | |
504 | if (!hrtimer_is_queued(tmr) && |
505 | tsk->signal->it_real_incr.tv64 != 0) { |
506 | hrtimer_forward(tmr, tmr->base->get_time(), |
507 | tsk->signal->it_real_incr); |
508 | hrtimer_restart(tmr); |
509 | } |
510 | } |
511 | } |
512 | |
513 | recalc_sigpending(); |
514 | if (!signr) |
515 | return 0; |
516 | |
517 | if (unlikely(sig_kernel_stop(signr))) { |
518 | /* |
519 | * Set a marker that we have dequeued a stop signal. Our |
520 | * caller might release the siglock and then the pending |
521 | * stop signal it is about to process is no longer in the |
522 | * pending bitmasks, but must still be cleared by a SIGCONT |
523 | * (and overruled by a SIGKILL). So those cases clear this |
524 | * shared flag after we've set it. Note that this flag may |
525 | * remain set after the signal we return is ignored or |
526 | * handled. That doesn't matter because its only purpose |
527 | * is to alert stop-signal processing code when another |
528 | * processor has come along and cleared the flag. |
529 | */ |
530 | tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; |
531 | } |
532 | if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) { |
533 | /* |
534 | * Release the siglock to ensure proper locking order |
535 | * of timer locks outside of siglocks. Note, we leave |
536 | * irqs disabled here, since the posix-timers code is |
537 | * about to disable them again anyway. |
538 | */ |
539 | spin_unlock(&tsk->sighand->siglock); |
540 | do_schedule_next_timer(info); |
541 | spin_lock(&tsk->sighand->siglock); |
542 | } |
543 | return signr; |
544 | } |
545 | |
546 | /* |
547 | * Tell a process that it has a new active signal.. |
548 | * |
549 | * NOTE! we rely on the previous spin_lock to |
550 | * lock interrupts for us! We can only be called with |
551 | * "siglock" held, and the local interrupt must |
552 | * have been disabled when that got acquired! |
553 | * |
554 | * No need to set need_resched since signal event passing |
555 | * goes through ->blocked |
556 | */ |
557 | void signal_wake_up(struct task_struct *t, int resume) |
558 | { |
559 | unsigned int mask; |
560 | |
561 | set_tsk_thread_flag(t, TIF_SIGPENDING); |
562 | |
563 | /* |
564 | * For SIGKILL, we want to wake it up in the stopped/traced/killable |
565 | * case. We don't check t->state here because there is a race with it |
566 | * executing another processor and just now entering stopped state. |
567 | * By using wake_up_state, we ensure the process will wake up and |
568 | * handle its death signal. |
569 | */ |
570 | mask = TASK_INTERRUPTIBLE; |
571 | if (resume) |
572 | mask |= TASK_WAKEKILL; |
573 | if (!wake_up_state(t, mask)) |
574 | kick_process(t); |
575 | } |
576 | |
577 | /* |
578 | * Remove signals in mask from the pending set and queue. |
579 | * Returns 1 if any signals were found. |
580 | * |
581 | * All callers must be holding the siglock. |
582 | * |
583 | * This version takes a sigset mask and looks at all signals, |
584 | * not just those in the first mask word. |
585 | */ |
586 | static int rm_from_queue_full(sigset_t *mask, struct sigpending *s) |
587 | { |
588 | struct sigqueue *q, *n; |
589 | sigset_t m; |
590 | |
591 | sigandsets(&m, mask, &s->signal); |
592 | if (sigisemptyset(&m)) |
593 | return 0; |
594 | |
595 | signandsets(&s->signal, &s->signal, mask); |
596 | list_for_each_entry_safe(q, n, &s->list, list) { |
597 | if (sigismember(mask, q->info.si_signo)) { |
598 | list_del_init(&q->list); |
599 | __sigqueue_free(q); |
600 | } |
601 | } |
602 | return 1; |
603 | } |
604 | /* |
605 | * Remove signals in mask from the pending set and queue. |
606 | * Returns 1 if any signals were found. |
607 | * |
608 | * All callers must be holding the siglock. |
609 | */ |
610 | static int rm_from_queue(unsigned long mask, struct sigpending *s) |
611 | { |
612 | struct sigqueue *q, *n; |
613 | |
614 | if (!sigtestsetmask(&s->signal, mask)) |
615 | return 0; |
616 | |
617 | sigdelsetmask(&s->signal, mask); |
618 | list_for_each_entry_safe(q, n, &s->list, list) { |
619 | if (q->info.si_signo < SIGRTMIN && |
620 | (mask & sigmask(q->info.si_signo))) { |
621 | list_del_init(&q->list); |
622 | __sigqueue_free(q); |
623 | } |
624 | } |
625 | return 1; |
626 | } |
627 | |
628 | static inline int is_si_special(const struct siginfo *info) |
629 | { |
630 | return info <= SEND_SIG_FORCED; |
631 | } |
632 | |
633 | static inline bool si_fromuser(const struct siginfo *info) |
634 | { |
635 | return info == SEND_SIG_NOINFO || |
636 | (!is_si_special(info) && SI_FROMUSER(info)); |
637 | } |
638 | |
639 | /* |
640 | * called with RCU read lock from check_kill_permission() |
641 | */ |
642 | static int kill_ok_by_cred(struct task_struct *t) |
643 | { |
644 | const struct cred *cred = current_cred(); |
645 | const struct cred *tcred = __task_cred(t); |
646 | |
647 | if (cred->user->user_ns == tcred->user->user_ns && |
648 | (cred->euid == tcred->suid || |
649 | cred->euid == tcred->uid || |
650 | cred->uid == tcred->suid || |
651 | cred->uid == tcred->uid)) |
652 | return 1; |
653 | |
654 | if (ns_capable(tcred->user->user_ns, CAP_KILL)) |
655 | return 1; |
656 | |
657 | return 0; |
658 | } |
659 | |
660 | /* |
661 | * Bad permissions for sending the signal |
662 | * - the caller must hold the RCU read lock |
663 | */ |
664 | static int check_kill_permission(int sig, struct siginfo *info, |
665 | struct task_struct *t) |
666 | { |
667 | struct pid *sid; |
668 | int error; |
669 | |
670 | if (!valid_signal(sig)) |
671 | return -EINVAL; |
672 | |
673 | if (!si_fromuser(info)) |
674 | return 0; |
675 | |
676 | error = audit_signal_info(sig, t); /* Let audit system see the signal */ |
677 | if (error) |
678 | return error; |
679 | |
680 | if (!same_thread_group(current, t) && |
681 | !kill_ok_by_cred(t)) { |
682 | switch (sig) { |
683 | case SIGCONT: |
684 | sid = task_session(t); |
685 | /* |
686 | * We don't return the error if sid == NULL. The |
687 | * task was unhashed, the caller must notice this. |
688 | */ |
689 | if (!sid || sid == task_session(current)) |
690 | break; |
691 | default: |
692 | return -EPERM; |
693 | } |
694 | } |
695 | |
696 | return security_task_kill(t, info, sig, 0); |
697 | } |
698 | |
699 | /* |
700 | * Handle magic process-wide effects of stop/continue signals. Unlike |
701 | * the signal actions, these happen immediately at signal-generation |
702 | * time regardless of blocking, ignoring, or handling. This does the |
703 | * actual continuing for SIGCONT, but not the actual stopping for stop |
704 | * signals. The process stop is done as a signal action for SIG_DFL. |
705 | * |
706 | * Returns true if the signal should be actually delivered, otherwise |
707 | * it should be dropped. |
708 | */ |
709 | static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) |
710 | { |
711 | struct signal_struct *signal = p->signal; |
712 | struct task_struct *t; |
713 | |
714 | if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) { |
715 | /* |
716 | * The process is in the middle of dying, nothing to do. |
717 | */ |
718 | } else if (sig_kernel_stop(sig)) { |
719 | /* |
720 | * This is a stop signal. Remove SIGCONT from all queues. |
721 | */ |
722 | rm_from_queue(sigmask(SIGCONT), &signal->shared_pending); |
723 | t = p; |
724 | do { |
725 | rm_from_queue(sigmask(SIGCONT), &t->pending); |
726 | } while_each_thread(p, t); |
727 | } else if (sig == SIGCONT) { |
728 | unsigned int why; |
729 | /* |
730 | * Remove all stop signals from all queues, |
731 | * and wake all threads. |
732 | */ |
733 | rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending); |
734 | t = p; |
735 | do { |
736 | unsigned int state; |
737 | rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); |
738 | /* |
739 | * If there is a handler for SIGCONT, we must make |
740 | * sure that no thread returns to user mode before |
741 | * we post the signal, in case it was the only |
742 | * thread eligible to run the signal handler--then |
743 | * it must not do anything between resuming and |
744 | * running the handler. With the TIF_SIGPENDING |
745 | * flag set, the thread will pause and acquire the |
746 | * siglock that we hold now and until we've queued |
747 | * the pending signal. |
748 | * |
749 | * Wake up the stopped thread _after_ setting |
750 | * TIF_SIGPENDING |
751 | */ |
752 | state = __TASK_STOPPED; |
753 | if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) { |
754 | set_tsk_thread_flag(t, TIF_SIGPENDING); |
755 | state |= TASK_INTERRUPTIBLE; |
756 | } |
757 | wake_up_state(t, state); |
758 | } while_each_thread(p, t); |
759 | |
760 | /* |
761 | * Notify the parent with CLD_CONTINUED if we were stopped. |
762 | * |
763 | * If we were in the middle of a group stop, we pretend it |
764 | * was already finished, and then continued. Since SIGCHLD |
765 | * doesn't queue we report only CLD_STOPPED, as if the next |
766 | * CLD_CONTINUED was dropped. |
767 | */ |
768 | why = 0; |
769 | if (signal->flags & SIGNAL_STOP_STOPPED) |
770 | why |= SIGNAL_CLD_CONTINUED; |
771 | else if (signal->group_stop_count) |
772 | why |= SIGNAL_CLD_STOPPED; |
773 | |
774 | if (why) { |
775 | /* |
776 | * The first thread which returns from do_signal_stop() |
777 | * will take ->siglock, notice SIGNAL_CLD_MASK, and |
778 | * notify its parent. See get_signal_to_deliver(). |
779 | */ |
780 | signal->flags = why | SIGNAL_STOP_CONTINUED; |
781 | signal->group_stop_count = 0; |
782 | signal->group_exit_code = 0; |
783 | } else { |
784 | /* |
785 | * We are not stopped, but there could be a stop |
786 | * signal in the middle of being processed after |
787 | * being removed from the queue. Clear that too. |
788 | */ |
789 | signal->flags &= ~SIGNAL_STOP_DEQUEUED; |
790 | } |
791 | } |
792 | |
793 | return !sig_ignored(p, sig, from_ancestor_ns); |
794 | } |
795 | |
796 | /* |
797 | * Test if P wants to take SIG. After we've checked all threads with this, |
798 | * it's equivalent to finding no threads not blocking SIG. Any threads not |
799 | * blocking SIG were ruled out because they are not running and already |
800 | * have pending signals. Such threads will dequeue from the shared queue |
801 | * as soon as they're available, so putting the signal on the shared queue |
802 | * will be equivalent to sending it to one such thread. |
803 | */ |
804 | static inline int wants_signal(int sig, struct task_struct *p) |
805 | { |
806 | if (sigismember(&p->blocked, sig)) |
807 | return 0; |
808 | if (p->flags & PF_EXITING) |
809 | return 0; |
810 | if (sig == SIGKILL) |
811 | return 1; |
812 | if (task_is_stopped_or_traced(p)) |
813 | return 0; |
814 | return task_curr(p) || !signal_pending(p); |
815 | } |
816 | |
817 | static void complete_signal(int sig, struct task_struct *p, int group) |
818 | { |
819 | struct signal_struct *signal = p->signal; |
820 | struct task_struct *t; |
821 | |
822 | /* |
823 | * Now find a thread we can wake up to take the signal off the queue. |
824 | * |
825 | * If the main thread wants the signal, it gets first crack. |
826 | * Probably the least surprising to the average bear. |
827 | */ |
828 | if (wants_signal(sig, p)) |
829 | t = p; |
830 | else if (!group || thread_group_empty(p)) |
831 | /* |
832 | * There is just one thread and it does not need to be woken. |
833 | * It will dequeue unblocked signals before it runs again. |
834 | */ |
835 | return; |
836 | else { |
837 | /* |
838 | * Otherwise try to find a suitable thread. |
839 | */ |
840 | t = signal->curr_target; |
841 | while (!wants_signal(sig, t)) { |
842 | t = next_thread(t); |
843 | if (t == signal->curr_target) |
844 | /* |
845 | * No thread needs to be woken. |
846 | * Any eligible threads will see |
847 | * the signal in the queue soon. |
848 | */ |
849 | return; |
850 | } |
851 | signal->curr_target = t; |
852 | } |
853 | |
854 | /* |
855 | * Found a killable thread. If the signal will be fatal, |
856 | * then start taking the whole group down immediately. |
857 | */ |
858 | if (sig_fatal(p, sig) && |
859 | !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) && |
860 | !sigismember(&t->real_blocked, sig) && |
861 | (sig == SIGKILL || |
862 | !tracehook_consider_fatal_signal(t, sig))) { |
863 | /* |
864 | * This signal will be fatal to the whole group. |
865 | */ |
866 | if (!sig_kernel_coredump(sig)) { |
867 | /* |
868 | * Start a group exit and wake everybody up. |
869 | * This way we don't have other threads |
870 | * running and doing things after a slower |
871 | * thread has the fatal signal pending. |
872 | */ |
873 | signal->flags = SIGNAL_GROUP_EXIT; |
874 | signal->group_exit_code = sig; |
875 | signal->group_stop_count = 0; |
876 | t = p; |
877 | do { |
878 | sigaddset(&t->pending.signal, SIGKILL); |
879 | signal_wake_up(t, 1); |
880 | } while_each_thread(p, t); |
881 | return; |
882 | } |
883 | } |
884 | |
885 | /* |
886 | * The signal is already in the shared-pending queue. |
887 | * Tell the chosen thread to wake up and dequeue it. |
888 | */ |
889 | signal_wake_up(t, sig == SIGKILL); |
890 | return; |
891 | } |
892 | |
893 | static inline int legacy_queue(struct sigpending *signals, int sig) |
894 | { |
895 | return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); |
896 | } |
897 | |
898 | static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, |
899 | int group, int from_ancestor_ns) |
900 | { |
901 | struct sigpending *pending; |
902 | struct sigqueue *q; |
903 | int override_rlimit; |
904 | |
905 | trace_signal_generate(sig, info, t); |
906 | |
907 | assert_spin_locked(&t->sighand->siglock); |
908 | |
909 | if (!prepare_signal(sig, t, from_ancestor_ns)) |
910 | return 0; |
911 | |
912 | pending = group ? &t->signal->shared_pending : &t->pending; |
913 | /* |
914 | * Short-circuit ignored signals and support queuing |
915 | * exactly one non-rt signal, so that we can get more |
916 | * detailed information about the cause of the signal. |
917 | */ |
918 | if (legacy_queue(pending, sig)) |
919 | return 0; |
920 | /* |
921 | * fast-pathed signals for kernel-internal things like SIGSTOP |
922 | * or SIGKILL. |
923 | */ |
924 | if (info == SEND_SIG_FORCED) |
925 | goto out_set; |
926 | |
927 | /* |
928 | * Real-time signals must be queued if sent by sigqueue, or |
929 | * some other real-time mechanism. It is implementation |
930 | * defined whether kill() does so. We attempt to do so, on |
931 | * the principle of least surprise, but since kill is not |
932 | * allowed to fail with EAGAIN when low on memory we just |
933 | * make sure at least one signal gets delivered and don't |
934 | * pass on the info struct. |
935 | */ |
936 | if (sig < SIGRTMIN) |
937 | override_rlimit = (is_si_special(info) || info->si_code >= 0); |
938 | else |
939 | override_rlimit = 0; |
940 | |
941 | q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE, |
942 | override_rlimit); |
943 | if (q) { |
944 | list_add_tail(&q->list, &pending->list); |
945 | switch ((unsigned long) info) { |
946 | case (unsigned long) SEND_SIG_NOINFO: |
947 | q->info.si_signo = sig; |
948 | q->info.si_errno = 0; |
949 | q->info.si_code = SI_USER; |
950 | q->info.si_pid = task_tgid_nr_ns(current, |
951 | task_active_pid_ns(t)); |
952 | q->info.si_uid = current_uid(); |
953 | break; |
954 | case (unsigned long) SEND_SIG_PRIV: |
955 | q->info.si_signo = sig; |
956 | q->info.si_errno = 0; |
957 | q->info.si_code = SI_KERNEL; |
958 | q->info.si_pid = 0; |
959 | q->info.si_uid = 0; |
960 | break; |
961 | default: |
962 | copy_siginfo(&q->info, info); |
963 | if (from_ancestor_ns) |
964 | q->info.si_pid = 0; |
965 | break; |
966 | } |
967 | } else if (!is_si_special(info)) { |
968 | if (sig >= SIGRTMIN && info->si_code != SI_USER) { |
969 | /* |
970 | * Queue overflow, abort. We may abort if the |
971 | * signal was rt and sent by user using something |
972 | * other than kill(). |
973 | */ |
974 | trace_signal_overflow_fail(sig, group, info); |
975 | return -EAGAIN; |
976 | } else { |
977 | /* |
978 | * This is a silent loss of information. We still |
979 | * send the signal, but the *info bits are lost. |
980 | */ |
981 | trace_signal_lose_info(sig, group, info); |
982 | } |
983 | } |
984 | |
985 | out_set: |
986 | signalfd_notify(t, sig); |
987 | sigaddset(&pending->signal, sig); |
988 | complete_signal(sig, t, group); |
989 | return 0; |
990 | } |
991 | |
992 | static int send_signal(int sig, struct siginfo *info, struct task_struct *t, |
993 | int group) |
994 | { |
995 | int from_ancestor_ns = 0; |
996 | |
997 | #ifdef CONFIG_PID_NS |
998 | from_ancestor_ns = si_fromuser(info) && |
999 | !task_pid_nr_ns(current, task_active_pid_ns(t)); |
1000 | #endif |
1001 | |
1002 | return __send_signal(sig, info, t, group, from_ancestor_ns); |
1003 | } |
1004 | |
1005 | static void print_fatal_signal(struct pt_regs *regs, int signr) |
1006 | { |
1007 | printk("%s/%d: potentially unexpected fatal signal %d.\n", |
1008 | current->comm, task_pid_nr(current), signr); |
1009 | |
1010 | #if defined(__i386__) && !defined(__arch_um__) |
1011 | printk("code at %08lx: ", regs->ip); |
1012 | { |
1013 | int i; |
1014 | for (i = 0; i < 16; i++) { |
1015 | unsigned char insn; |
1016 | |
1017 | if (get_user(insn, (unsigned char *)(regs->ip + i))) |
1018 | break; |
1019 | printk("%02x ", insn); |
1020 | } |
1021 | } |
1022 | #endif |
1023 | printk("\n"); |
1024 | preempt_disable(); |
1025 | show_regs(regs); |
1026 | preempt_enable(); |
1027 | } |
1028 | |
1029 | static int __init setup_print_fatal_signals(char *str) |
1030 | { |
1031 | get_option (&str, &print_fatal_signals); |
1032 | |
1033 | return 1; |
1034 | } |
1035 | |
1036 | __setup("print-fatal-signals=", setup_print_fatal_signals); |
1037 | |
1038 | int |
1039 | __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) |
1040 | { |
1041 | return send_signal(sig, info, p, 1); |
1042 | } |
1043 | |
1044 | static int |
1045 | specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) |
1046 | { |
1047 | return send_signal(sig, info, t, 0); |
1048 | } |
1049 | |
1050 | int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p, |
1051 | bool group) |
1052 | { |
1053 | unsigned long flags; |
1054 | int ret = -ESRCH; |
1055 | |
1056 | if (lock_task_sighand(p, &flags)) { |
1057 | ret = send_signal(sig, info, p, group); |
1058 | unlock_task_sighand(p, &flags); |
1059 | } |
1060 | |
1061 | return ret; |
1062 | } |
1063 | |
1064 | /* |
1065 | * Force a signal that the process can't ignore: if necessary |
1066 | * we unblock the signal and change any SIG_IGN to SIG_DFL. |
1067 | * |
1068 | * Note: If we unblock the signal, we always reset it to SIG_DFL, |
1069 | * since we do not want to have a signal handler that was blocked |
1070 | * be invoked when user space had explicitly blocked it. |
1071 | * |
1072 | * We don't want to have recursive SIGSEGV's etc, for example, |
1073 | * that is why we also clear SIGNAL_UNKILLABLE. |
1074 | */ |
1075 | int |
1076 | force_sig_info(int sig, struct siginfo *info, struct task_struct *t) |
1077 | { |
1078 | unsigned long int flags; |
1079 | int ret, blocked, ignored; |
1080 | struct k_sigaction *action; |
1081 | |
1082 | spin_lock_irqsave(&t->sighand->siglock, flags); |
1083 | action = &t->sighand->action[sig-1]; |
1084 | ignored = action->sa.sa_handler == SIG_IGN; |
1085 | blocked = sigismember(&t->blocked, sig); |
1086 | if (blocked || ignored) { |
1087 | action->sa.sa_handler = SIG_DFL; |
1088 | if (blocked) { |
1089 | sigdelset(&t->blocked, sig); |
1090 | recalc_sigpending_and_wake(t); |
1091 | } |
1092 | } |
1093 | if (action->sa.sa_handler == SIG_DFL) |
1094 | t->signal->flags &= ~SIGNAL_UNKILLABLE; |
1095 | ret = specific_send_sig_info(sig, info, t); |
1096 | spin_unlock_irqrestore(&t->sighand->siglock, flags); |
1097 | |
1098 | return ret; |
1099 | } |
1100 | |
1101 | /* |
1102 | * Nuke all other threads in the group. |
1103 | */ |
1104 | int zap_other_threads(struct task_struct *p) |
1105 | { |
1106 | struct task_struct *t = p; |
1107 | int count = 0; |
1108 | |
1109 | p->signal->group_stop_count = 0; |
1110 | |
1111 | while_each_thread(p, t) { |
1112 | count++; |
1113 | |
1114 | /* Don't bother with already dead threads */ |
1115 | if (t->exit_state) |
1116 | continue; |
1117 | sigaddset(&t->pending.signal, SIGKILL); |
1118 | signal_wake_up(t, 1); |
1119 | } |
1120 | |
1121 | return count; |
1122 | } |
1123 | |
1124 | struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, |
1125 | unsigned long *flags) |
1126 | { |
1127 | struct sighand_struct *sighand; |
1128 | |
1129 | rcu_read_lock(); |
1130 | for (;;) { |
1131 | sighand = rcu_dereference(tsk->sighand); |
1132 | if (unlikely(sighand == NULL)) |
1133 | break; |
1134 | |
1135 | spin_lock_irqsave(&sighand->siglock, *flags); |
1136 | if (likely(sighand == tsk->sighand)) |
1137 | break; |
1138 | spin_unlock_irqrestore(&sighand->siglock, *flags); |
1139 | } |
1140 | rcu_read_unlock(); |
1141 | |
1142 | return sighand; |
1143 | } |
1144 | |
1145 | /* |
1146 | * send signal info to all the members of a group |
1147 | */ |
1148 | int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) |
1149 | { |
1150 | int ret; |
1151 | |
1152 | rcu_read_lock(); |
1153 | ret = check_kill_permission(sig, info, p); |
1154 | rcu_read_unlock(); |
1155 | |
1156 | if (!ret && sig) |
1157 | ret = do_send_sig_info(sig, info, p, true); |
1158 | |
1159 | return ret; |
1160 | } |
1161 | |
1162 | /* |
1163 | * __kill_pgrp_info() sends a signal to a process group: this is what the tty |
1164 | * control characters do (^C, ^Z etc) |
1165 | * - the caller must hold at least a readlock on tasklist_lock |
1166 | */ |
1167 | int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp) |
1168 | { |
1169 | struct task_struct *p = NULL; |
1170 | int retval, success; |
1171 | |
1172 | success = 0; |
1173 | retval = -ESRCH; |
1174 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
1175 | int err = group_send_sig_info(sig, info, p); |
1176 | success |= !err; |
1177 | retval = err; |
1178 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
1179 | return success ? 0 : retval; |
1180 | } |
1181 | |
1182 | int kill_pid_info(int sig, struct siginfo *info, struct pid *pid) |
1183 | { |
1184 | int error = -ESRCH; |
1185 | struct task_struct *p; |
1186 | |
1187 | rcu_read_lock(); |
1188 | retry: |
1189 | p = pid_task(pid, PIDTYPE_PID); |
1190 | if (p) { |
1191 | error = group_send_sig_info(sig, info, p); |
1192 | if (unlikely(error == -ESRCH)) |
1193 | /* |
1194 | * The task was unhashed in between, try again. |
1195 | * If it is dead, pid_task() will return NULL, |
1196 | * if we race with de_thread() it will find the |
1197 | * new leader. |
1198 | */ |
1199 | goto retry; |
1200 | } |
1201 | rcu_read_unlock(); |
1202 | |
1203 | return error; |
1204 | } |
1205 | |
1206 | int kill_proc_info(int sig, struct siginfo *info, pid_t pid) |
1207 | { |
1208 | int error; |
1209 | rcu_read_lock(); |
1210 | error = kill_pid_info(sig, info, find_vpid(pid)); |
1211 | rcu_read_unlock(); |
1212 | return error; |
1213 | } |
1214 | |
1215 | /* like kill_pid_info(), but doesn't use uid/euid of "current" */ |
1216 | int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid, |
1217 | uid_t uid, uid_t euid, u32 secid) |
1218 | { |
1219 | int ret = -EINVAL; |
1220 | struct task_struct *p; |
1221 | const struct cred *pcred; |
1222 | unsigned long flags; |
1223 | |
1224 | if (!valid_signal(sig)) |
1225 | return ret; |
1226 | |
1227 | rcu_read_lock(); |
1228 | p = pid_task(pid, PIDTYPE_PID); |
1229 | if (!p) { |
1230 | ret = -ESRCH; |
1231 | goto out_unlock; |
1232 | } |
1233 | pcred = __task_cred(p); |
1234 | if (si_fromuser(info) && |
1235 | euid != pcred->suid && euid != pcred->uid && |
1236 | uid != pcred->suid && uid != pcred->uid) { |
1237 | ret = -EPERM; |
1238 | goto out_unlock; |
1239 | } |
1240 | ret = security_task_kill(p, info, sig, secid); |
1241 | if (ret) |
1242 | goto out_unlock; |
1243 | |
1244 | if (sig) { |
1245 | if (lock_task_sighand(p, &flags)) { |
1246 | ret = __send_signal(sig, info, p, 1, 0); |
1247 | unlock_task_sighand(p, &flags); |
1248 | } else |
1249 | ret = -ESRCH; |
1250 | } |
1251 | out_unlock: |
1252 | rcu_read_unlock(); |
1253 | return ret; |
1254 | } |
1255 | EXPORT_SYMBOL_GPL(kill_pid_info_as_uid); |
1256 | |
1257 | /* |
1258 | * kill_something_info() interprets pid in interesting ways just like kill(2). |
1259 | * |
1260 | * POSIX specifies that kill(-1,sig) is unspecified, but what we have |
1261 | * is probably wrong. Should make it like BSD or SYSV. |
1262 | */ |
1263 | |
1264 | static int kill_something_info(int sig, struct siginfo *info, pid_t pid) |
1265 | { |
1266 | int ret; |
1267 | |
1268 | if (pid > 0) { |
1269 | rcu_read_lock(); |
1270 | ret = kill_pid_info(sig, info, find_vpid(pid)); |
1271 | rcu_read_unlock(); |
1272 | return ret; |
1273 | } |
1274 | |
1275 | read_lock(&tasklist_lock); |
1276 | if (pid != -1) { |
1277 | ret = __kill_pgrp_info(sig, info, |
1278 | pid ? find_vpid(-pid) : task_pgrp(current)); |
1279 | } else { |
1280 | int retval = 0, count = 0; |
1281 | struct task_struct * p; |
1282 | |
1283 | for_each_process(p) { |
1284 | if (task_pid_vnr(p) > 1 && |
1285 | !same_thread_group(p, current)) { |
1286 | int err = group_send_sig_info(sig, info, p); |
1287 | ++count; |
1288 | if (err != -EPERM) |
1289 | retval = err; |
1290 | } |
1291 | } |
1292 | ret = count ? retval : -ESRCH; |
1293 | } |
1294 | read_unlock(&tasklist_lock); |
1295 | |
1296 | return ret; |
1297 | } |
1298 | |
1299 | /* |
1300 | * These are for backward compatibility with the rest of the kernel source. |
1301 | */ |
1302 | |
1303 | int send_sig_info(int sig, struct siginfo *info, struct task_struct *p) |
1304 | { |
1305 | /* |
1306 | * Make sure legacy kernel users don't send in bad values |
1307 | * (normal paths check this in check_kill_permission). |
1308 | */ |
1309 | if (!valid_signal(sig)) |
1310 | return -EINVAL; |
1311 | |
1312 | return do_send_sig_info(sig, info, p, false); |
1313 | } |
1314 | |
1315 | #define __si_special(priv) \ |
1316 | ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO) |
1317 | |
1318 | int |
1319 | send_sig(int sig, struct task_struct *p, int priv) |
1320 | { |
1321 | return send_sig_info(sig, __si_special(priv), p); |
1322 | } |
1323 | |
1324 | void |
1325 | force_sig(int sig, struct task_struct *p) |
1326 | { |
1327 | force_sig_info(sig, SEND_SIG_PRIV, p); |
1328 | } |
1329 | |
1330 | /* |
1331 | * When things go south during signal handling, we |
1332 | * will force a SIGSEGV. And if the signal that caused |
1333 | * the problem was already a SIGSEGV, we'll want to |
1334 | * make sure we don't even try to deliver the signal.. |
1335 | */ |
1336 | int |
1337 | force_sigsegv(int sig, struct task_struct *p) |
1338 | { |
1339 | if (sig == SIGSEGV) { |
1340 | unsigned long flags; |
1341 | spin_lock_irqsave(&p->sighand->siglock, flags); |
1342 | p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; |
1343 | spin_unlock_irqrestore(&p->sighand->siglock, flags); |
1344 | } |
1345 | force_sig(SIGSEGV, p); |
1346 | return 0; |
1347 | } |
1348 | |
1349 | int kill_pgrp(struct pid *pid, int sig, int priv) |
1350 | { |
1351 | int ret; |
1352 | |
1353 | read_lock(&tasklist_lock); |
1354 | ret = __kill_pgrp_info(sig, __si_special(priv), pid); |
1355 | read_unlock(&tasklist_lock); |
1356 | |
1357 | return ret; |
1358 | } |
1359 | EXPORT_SYMBOL(kill_pgrp); |
1360 | |
1361 | int kill_pid(struct pid *pid, int sig, int priv) |
1362 | { |
1363 | return kill_pid_info(sig, __si_special(priv), pid); |
1364 | } |
1365 | EXPORT_SYMBOL(kill_pid); |
1366 | |
1367 | /* |
1368 | * These functions support sending signals using preallocated sigqueue |
1369 | * structures. This is needed "because realtime applications cannot |
1370 | * afford to lose notifications of asynchronous events, like timer |
1371 | * expirations or I/O completions". In the case of POSIX Timers |
1372 | * we allocate the sigqueue structure from the timer_create. If this |
1373 | * allocation fails we are able to report the failure to the application |
1374 | * with an EAGAIN error. |
1375 | */ |
1376 | struct sigqueue *sigqueue_alloc(void) |
1377 | { |
1378 | struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0); |
1379 | |
1380 | if (q) |
1381 | q->flags |= SIGQUEUE_PREALLOC; |
1382 | |
1383 | return q; |
1384 | } |
1385 | |
1386 | void sigqueue_free(struct sigqueue *q) |
1387 | { |
1388 | unsigned long flags; |
1389 | spinlock_t *lock = ¤t->sighand->siglock; |
1390 | |
1391 | BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); |
1392 | /* |
1393 | * We must hold ->siglock while testing q->list |
1394 | * to serialize with collect_signal() or with |
1395 | * __exit_signal()->flush_sigqueue(). |
1396 | */ |
1397 | spin_lock_irqsave(lock, flags); |
1398 | q->flags &= ~SIGQUEUE_PREALLOC; |
1399 | /* |
1400 | * If it is queued it will be freed when dequeued, |
1401 | * like the "regular" sigqueue. |
1402 | */ |
1403 | if (!list_empty(&q->list)) |
1404 | q = NULL; |
1405 | spin_unlock_irqrestore(lock, flags); |
1406 | |
1407 | if (q) |
1408 | __sigqueue_free(q); |
1409 | } |
1410 | |
1411 | int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) |
1412 | { |
1413 | int sig = q->info.si_signo; |
1414 | struct sigpending *pending; |
1415 | unsigned long flags; |
1416 | int ret; |
1417 | |
1418 | BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); |
1419 | |
1420 | ret = -1; |
1421 | if (!likely(lock_task_sighand(t, &flags))) |
1422 | goto ret; |
1423 | |
1424 | ret = 1; /* the signal is ignored */ |
1425 | if (!prepare_signal(sig, t, 0)) |
1426 | goto out; |
1427 | |
1428 | ret = 0; |
1429 | if (unlikely(!list_empty(&q->list))) { |
1430 | /* |
1431 | * If an SI_TIMER entry is already queue just increment |
1432 | * the overrun count. |
1433 | */ |
1434 | BUG_ON(q->info.si_code != SI_TIMER); |
1435 | q->info.si_overrun++; |
1436 | goto out; |
1437 | } |
1438 | q->info.si_overrun = 0; |
1439 | |
1440 | signalfd_notify(t, sig); |
1441 | pending = group ? &t->signal->shared_pending : &t->pending; |
1442 | list_add_tail(&q->list, &pending->list); |
1443 | sigaddset(&pending->signal, sig); |
1444 | complete_signal(sig, t, group); |
1445 | out: |
1446 | unlock_task_sighand(t, &flags); |
1447 | ret: |
1448 | return ret; |
1449 | } |
1450 | |
1451 | /* |
1452 | * Let a parent know about the death of a child. |
1453 | * For a stopped/continued status change, use do_notify_parent_cldstop instead. |
1454 | * |
1455 | * Returns -1 if our parent ignored us and so we've switched to |
1456 | * self-reaping, or else @sig. |
1457 | */ |
1458 | int do_notify_parent(struct task_struct *tsk, int sig) |
1459 | { |
1460 | struct siginfo info; |
1461 | unsigned long flags; |
1462 | struct sighand_struct *psig; |
1463 | int ret = sig; |
1464 | |
1465 | BUG_ON(sig == -1); |
1466 | |
1467 | /* do_notify_parent_cldstop should have been called instead. */ |
1468 | BUG_ON(task_is_stopped_or_traced(tsk)); |
1469 | |
1470 | BUG_ON(!task_ptrace(tsk) && |
1471 | (tsk->group_leader != tsk || !thread_group_empty(tsk))); |
1472 | |
1473 | info.si_signo = sig; |
1474 | info.si_errno = 0; |
1475 | /* |
1476 | * we are under tasklist_lock here so our parent is tied to |
1477 | * us and cannot exit and release its namespace. |
1478 | * |
1479 | * the only it can is to switch its nsproxy with sys_unshare, |
1480 | * bu uncharing pid namespaces is not allowed, so we'll always |
1481 | * see relevant namespace |
1482 | * |
1483 | * write_lock() currently calls preempt_disable() which is the |
1484 | * same as rcu_read_lock(), but according to Oleg, this is not |
1485 | * correct to rely on this |
1486 | */ |
1487 | rcu_read_lock(); |
1488 | info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns); |
1489 | info.si_uid = __task_cred(tsk)->uid; |
1490 | rcu_read_unlock(); |
1491 | |
1492 | info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime, |
1493 | tsk->signal->utime)); |
1494 | info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime, |
1495 | tsk->signal->stime)); |
1496 | |
1497 | info.si_status = tsk->exit_code & 0x7f; |
1498 | if (tsk->exit_code & 0x80) |
1499 | info.si_code = CLD_DUMPED; |
1500 | else if (tsk->exit_code & 0x7f) |
1501 | info.si_code = CLD_KILLED; |
1502 | else { |
1503 | info.si_code = CLD_EXITED; |
1504 | info.si_status = tsk->exit_code >> 8; |
1505 | } |
1506 | |
1507 | psig = tsk->parent->sighand; |
1508 | spin_lock_irqsave(&psig->siglock, flags); |
1509 | if (!task_ptrace(tsk) && sig == SIGCHLD && |
1510 | (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || |
1511 | (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { |
1512 | /* |
1513 | * We are exiting and our parent doesn't care. POSIX.1 |
1514 | * defines special semantics for setting SIGCHLD to SIG_IGN |
1515 | * or setting the SA_NOCLDWAIT flag: we should be reaped |
1516 | * automatically and not left for our parent's wait4 call. |
1517 | * Rather than having the parent do it as a magic kind of |
1518 | * signal handler, we just set this to tell do_exit that we |
1519 | * can be cleaned up without becoming a zombie. Note that |
1520 | * we still call __wake_up_parent in this case, because a |
1521 | * blocked sys_wait4 might now return -ECHILD. |
1522 | * |
1523 | * Whether we send SIGCHLD or not for SA_NOCLDWAIT |
1524 | * is implementation-defined: we do (if you don't want |
1525 | * it, just use SIG_IGN instead). |
1526 | */ |
1527 | ret = tsk->exit_signal = -1; |
1528 | if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) |
1529 | sig = -1; |
1530 | } |
1531 | if (valid_signal(sig) && sig > 0) |
1532 | __group_send_sig_info(sig, &info, tsk->parent); |
1533 | __wake_up_parent(tsk, tsk->parent); |
1534 | spin_unlock_irqrestore(&psig->siglock, flags); |
1535 | |
1536 | return ret; |
1537 | } |
1538 | |
1539 | static void do_notify_parent_cldstop(struct task_struct *tsk, int why) |
1540 | { |
1541 | struct siginfo info; |
1542 | unsigned long flags; |
1543 | struct task_struct *parent; |
1544 | struct sighand_struct *sighand; |
1545 | |
1546 | if (task_ptrace(tsk)) |
1547 | parent = tsk->parent; |
1548 | else { |
1549 | tsk = tsk->group_leader; |
1550 | parent = tsk->real_parent; |
1551 | } |
1552 | |
1553 | info.si_signo = SIGCHLD; |
1554 | info.si_errno = 0; |
1555 | /* |
1556 | * see comment in do_notify_parent() about the following 4 lines |
1557 | */ |
1558 | rcu_read_lock(); |
1559 | info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns); |
1560 | info.si_uid = __task_cred(tsk)->uid; |
1561 | rcu_read_unlock(); |
1562 | |
1563 | info.si_utime = cputime_to_clock_t(tsk->utime); |
1564 | info.si_stime = cputime_to_clock_t(tsk->stime); |
1565 | |
1566 | info.si_code = why; |
1567 | switch (why) { |
1568 | case CLD_CONTINUED: |
1569 | info.si_status = SIGCONT; |
1570 | break; |
1571 | case CLD_STOPPED: |
1572 | info.si_status = tsk->signal->group_exit_code & 0x7f; |
1573 | break; |
1574 | case CLD_TRAPPED: |
1575 | info.si_status = tsk->exit_code & 0x7f; |
1576 | break; |
1577 | default: |
1578 | BUG(); |
1579 | } |
1580 | |
1581 | sighand = parent->sighand; |
1582 | spin_lock_irqsave(&sighand->siglock, flags); |
1583 | if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && |
1584 | !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP)) |
1585 | __group_send_sig_info(SIGCHLD, &info, parent); |
1586 | /* |
1587 | * Even if SIGCHLD is not generated, we must wake up wait4 calls. |
1588 | */ |
1589 | __wake_up_parent(tsk, parent); |
1590 | spin_unlock_irqrestore(&sighand->siglock, flags); |
1591 | } |
1592 | |
1593 | static inline int may_ptrace_stop(void) |
1594 | { |
1595 | if (!likely(task_ptrace(current))) |
1596 | return 0; |
1597 | /* |
1598 | * Are we in the middle of do_coredump? |
1599 | * If so and our tracer is also part of the coredump stopping |
1600 | * is a deadlock situation, and pointless because our tracer |
1601 | * is dead so don't allow us to stop. |
1602 | * If SIGKILL was already sent before the caller unlocked |
1603 | * ->siglock we must see ->core_state != NULL. Otherwise it |
1604 | * is safe to enter schedule(). |
1605 | */ |
1606 | if (unlikely(current->mm->core_state) && |
1607 | unlikely(current->mm == current->parent->mm)) |
1608 | return 0; |
1609 | |
1610 | return 1; |
1611 | } |
1612 | |
1613 | /* |
1614 | * Return non-zero if there is a SIGKILL that should be waking us up. |
1615 | * Called with the siglock held. |
1616 | */ |
1617 | static int sigkill_pending(struct task_struct *tsk) |
1618 | { |
1619 | return sigismember(&tsk->pending.signal, SIGKILL) || |
1620 | sigismember(&tsk->signal->shared_pending.signal, SIGKILL); |
1621 | } |
1622 | |
1623 | /* |
1624 | * This must be called with current->sighand->siglock held. |
1625 | * |
1626 | * This should be the path for all ptrace stops. |
1627 | * We always set current->last_siginfo while stopped here. |
1628 | * That makes it a way to test a stopped process for |
1629 | * being ptrace-stopped vs being job-control-stopped. |
1630 | * |
1631 | * If we actually decide not to stop at all because the tracer |
1632 | * is gone, we keep current->exit_code unless clear_code. |
1633 | */ |
1634 | static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) |
1635 | __releases(¤t->sighand->siglock) |
1636 | __acquires(¤t->sighand->siglock) |
1637 | { |
1638 | if (arch_ptrace_stop_needed(exit_code, info)) { |
1639 | /* |
1640 | * The arch code has something special to do before a |
1641 | * ptrace stop. This is allowed to block, e.g. for faults |
1642 | * on user stack pages. We can't keep the siglock while |
1643 | * calling arch_ptrace_stop, so we must release it now. |
1644 | * To preserve proper semantics, we must do this before |
1645 | * any signal bookkeeping like checking group_stop_count. |
1646 | * Meanwhile, a SIGKILL could come in before we retake the |
1647 | * siglock. That must prevent us from sleeping in TASK_TRACED. |
1648 | * So after regaining the lock, we must check for SIGKILL. |
1649 | */ |
1650 | spin_unlock_irq(¤t->sighand->siglock); |
1651 | arch_ptrace_stop(exit_code, info); |
1652 | spin_lock_irq(¤t->sighand->siglock); |
1653 | if (sigkill_pending(current)) |
1654 | return; |
1655 | } |
1656 | |
1657 | /* |
1658 | * If there is a group stop in progress, |
1659 | * we must participate in the bookkeeping. |
1660 | */ |
1661 | if (current->signal->group_stop_count > 0) |
1662 | --current->signal->group_stop_count; |
1663 | |
1664 | current->last_siginfo = info; |
1665 | current->exit_code = exit_code; |
1666 | |
1667 | /* Let the debugger run. */ |
1668 | __set_current_state(TASK_TRACED); |
1669 | spin_unlock_irq(¤t->sighand->siglock); |
1670 | read_lock(&tasklist_lock); |
1671 | if (may_ptrace_stop()) { |
1672 | do_notify_parent_cldstop(current, CLD_TRAPPED); |
1673 | /* |
1674 | * Don't want to allow preemption here, because |
1675 | * sys_ptrace() needs this task to be inactive. |
1676 | * |
1677 | * XXX: implement read_unlock_no_resched(). |
1678 | */ |
1679 | preempt_disable(); |
1680 | read_unlock(&tasklist_lock); |
1681 | preempt_enable_no_resched(); |
1682 | schedule(); |
1683 | } else { |
1684 | /* |
1685 | * By the time we got the lock, our tracer went away. |
1686 | * Don't drop the lock yet, another tracer may come. |
1687 | */ |
1688 | __set_current_state(TASK_RUNNING); |
1689 | if (clear_code) |
1690 | current->exit_code = 0; |
1691 | read_unlock(&tasklist_lock); |
1692 | } |
1693 | |
1694 | /* |
1695 | * While in TASK_TRACED, we were considered "frozen enough". |
1696 | * Now that we woke up, it's crucial if we're supposed to be |
1697 | * frozen that we freeze now before running anything substantial. |
1698 | */ |
1699 | try_to_freeze(); |
1700 | |
1701 | /* |
1702 | * We are back. Now reacquire the siglock before touching |
1703 | * last_siginfo, so that we are sure to have synchronized with |
1704 | * any signal-sending on another CPU that wants to examine it. |
1705 | */ |
1706 | spin_lock_irq(¤t->sighand->siglock); |
1707 | current->last_siginfo = NULL; |
1708 | |
1709 | /* |
1710 | * Queued signals ignored us while we were stopped for tracing. |
1711 | * So check for any that we should take before resuming user mode. |
1712 | * This sets TIF_SIGPENDING, but never clears it. |
1713 | */ |
1714 | recalc_sigpending_tsk(current); |
1715 | } |
1716 | |
1717 | void ptrace_notify(int exit_code) |
1718 | { |
1719 | siginfo_t info; |
1720 | |
1721 | BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); |
1722 | |
1723 | memset(&info, 0, sizeof info); |
1724 | info.si_signo = SIGTRAP; |
1725 | info.si_code = exit_code; |
1726 | info.si_pid = task_pid_vnr(current); |
1727 | info.si_uid = current_uid(); |
1728 | |
1729 | /* Let the debugger run. */ |
1730 | spin_lock_irq(¤t->sighand->siglock); |
1731 | ptrace_stop(exit_code, 1, &info); |
1732 | spin_unlock_irq(¤t->sighand->siglock); |
1733 | } |
1734 | |
1735 | /* |
1736 | * This performs the stopping for SIGSTOP and other stop signals. |
1737 | * We have to stop all threads in the thread group. |
1738 | * Returns non-zero if we've actually stopped and released the siglock. |
1739 | * Returns zero if we didn't stop and still hold the siglock. |
1740 | */ |
1741 | static int do_signal_stop(int signr) |
1742 | { |
1743 | struct signal_struct *sig = current->signal; |
1744 | int notify; |
1745 | |
1746 | if (!sig->group_stop_count) { |
1747 | struct task_struct *t; |
1748 | |
1749 | if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) || |
1750 | unlikely(signal_group_exit(sig))) |
1751 | return 0; |
1752 | /* |
1753 | * There is no group stop already in progress. |
1754 | * We must initiate one now. |
1755 | */ |
1756 | sig->group_exit_code = signr; |
1757 | |
1758 | sig->group_stop_count = 1; |
1759 | for (t = next_thread(current); t != current; t = next_thread(t)) |
1760 | /* |
1761 | * Setting state to TASK_STOPPED for a group |
1762 | * stop is always done with the siglock held, |
1763 | * so this check has no races. |
1764 | */ |
1765 | if (!(t->flags & PF_EXITING) && |
1766 | !task_is_stopped_or_traced(t)) { |
1767 | sig->group_stop_count++; |
1768 | signal_wake_up(t, 0); |
1769 | } |
1770 | } |
1771 | /* |
1772 | * If there are no other threads in the group, or if there is |
1773 | * a group stop in progress and we are the last to stop, report |
1774 | * to the parent. When ptraced, every thread reports itself. |
1775 | */ |
1776 | notify = sig->group_stop_count == 1 ? CLD_STOPPED : 0; |
1777 | notify = tracehook_notify_jctl(notify, CLD_STOPPED); |
1778 | /* |
1779 | * tracehook_notify_jctl() can drop and reacquire siglock, so |
1780 | * we keep ->group_stop_count != 0 before the call. If SIGCONT |
1781 | * or SIGKILL comes in between ->group_stop_count == 0. |
1782 | */ |
1783 | if (sig->group_stop_count) { |
1784 | if (!--sig->group_stop_count) |
1785 | sig->flags = SIGNAL_STOP_STOPPED; |
1786 | current->exit_code = sig->group_exit_code; |
1787 | __set_current_state(TASK_STOPPED); |
1788 | } |
1789 | spin_unlock_irq(¤t->sighand->siglock); |
1790 | |
1791 | if (notify) { |
1792 | read_lock(&tasklist_lock); |
1793 | do_notify_parent_cldstop(current, notify); |
1794 | read_unlock(&tasklist_lock); |
1795 | } |
1796 | |
1797 | /* Now we don't run again until woken by SIGCONT or SIGKILL */ |
1798 | do { |
1799 | schedule(); |
1800 | } while (try_to_freeze()); |
1801 | |
1802 | tracehook_finish_jctl(); |
1803 | current->exit_code = 0; |
1804 | |
1805 | return 1; |
1806 | } |
1807 | |
1808 | static int ptrace_signal(int signr, siginfo_t *info, |
1809 | struct pt_regs *regs, void *cookie) |
1810 | { |
1811 | if (!task_ptrace(current)) |
1812 | return signr; |
1813 | |
1814 | ptrace_signal_deliver(regs, cookie); |
1815 | |
1816 | /* Let the debugger run. */ |
1817 | ptrace_stop(signr, 0, info); |
1818 | |
1819 | /* We're back. Did the debugger cancel the sig? */ |
1820 | signr = current->exit_code; |
1821 | if (signr == 0) |
1822 | return signr; |
1823 | |
1824 | current->exit_code = 0; |
1825 | |
1826 | /* |
1827 | * Update the siginfo structure if the signal has |
1828 | * changed. If the debugger wanted something |
1829 | * specific in the siginfo structure then it should |
1830 | * have updated *info via PTRACE_SETSIGINFO. |
1831 | */ |
1832 | if (signr != info->si_signo) { |
1833 | info->si_signo = signr; |
1834 | info->si_errno = 0; |
1835 | info->si_code = SI_USER; |
1836 | info->si_pid = task_pid_vnr(current->parent); |
1837 | info->si_uid = task_uid(current->parent); |
1838 | } |
1839 | |
1840 | /* If the (new) signal is now blocked, requeue it. */ |
1841 | if (sigismember(¤t->blocked, signr)) { |
1842 | specific_send_sig_info(signr, info, current); |
1843 | signr = 0; |
1844 | } |
1845 | |
1846 | return signr; |
1847 | } |
1848 | |
1849 | int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, |
1850 | struct pt_regs *regs, void *cookie) |
1851 | { |
1852 | struct sighand_struct *sighand = current->sighand; |
1853 | struct signal_struct *signal = current->signal; |
1854 | int signr; |
1855 | |
1856 | relock: |
1857 | /* |
1858 | * We'll jump back here after any time we were stopped in TASK_STOPPED. |
1859 | * While in TASK_STOPPED, we were considered "frozen enough". |
1860 | * Now that we woke up, it's crucial if we're supposed to be |
1861 | * frozen that we freeze now before running anything substantial. |
1862 | */ |
1863 | try_to_freeze(); |
1864 | |
1865 | spin_lock_irq(&sighand->siglock); |
1866 | /* |
1867 | * Every stopped thread goes here after wakeup. Check to see if |
1868 | * we should notify the parent, prepare_signal(SIGCONT) encodes |
1869 | * the CLD_ si_code into SIGNAL_CLD_MASK bits. |
1870 | */ |
1871 | if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { |
1872 | int why = (signal->flags & SIGNAL_STOP_CONTINUED) |
1873 | ? CLD_CONTINUED : CLD_STOPPED; |
1874 | signal->flags &= ~SIGNAL_CLD_MASK; |
1875 | |
1876 | why = tracehook_notify_jctl(why, CLD_CONTINUED); |
1877 | spin_unlock_irq(&sighand->siglock); |
1878 | |
1879 | if (why) { |
1880 | read_lock(&tasklist_lock); |
1881 | do_notify_parent_cldstop(current->group_leader, why); |
1882 | read_unlock(&tasklist_lock); |
1883 | } |
1884 | goto relock; |
1885 | } |
1886 | |
1887 | for (;;) { |
1888 | struct k_sigaction *ka; |
1889 | /* |
1890 | * Tracing can induce an artificial signal and choose sigaction. |
1891 | * The return value in @signr determines the default action, |
1892 | * but @info->si_signo is the signal number we will report. |
1893 | */ |
1894 | signr = tracehook_get_signal(current, regs, info, return_ka); |
1895 | if (unlikely(signr < 0)) |
1896 | goto relock; |
1897 | if (unlikely(signr != 0)) |
1898 | ka = return_ka; |
1899 | else { |
1900 | if (unlikely(signal->group_stop_count > 0) && |
1901 | do_signal_stop(0)) |
1902 | goto relock; |
1903 | |
1904 | signr = dequeue_signal(current, ¤t->blocked, |
1905 | info); |
1906 | |
1907 | if (!signr) |
1908 | break; /* will return 0 */ |
1909 | |
1910 | if (signr != SIGKILL) { |
1911 | signr = ptrace_signal(signr, info, |
1912 | regs, cookie); |
1913 | if (!signr) |
1914 | continue; |
1915 | } |
1916 | |
1917 | ka = &sighand->action[signr-1]; |
1918 | } |
1919 | |
1920 | /* Trace actually delivered signals. */ |
1921 | trace_signal_deliver(signr, info, ka); |
1922 | |
1923 | if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ |
1924 | continue; |
1925 | if (ka->sa.sa_handler != SIG_DFL) { |
1926 | /* Run the handler. */ |
1927 | *return_ka = *ka; |
1928 | |
1929 | if (ka->sa.sa_flags & SA_ONESHOT) |
1930 | ka->sa.sa_handler = SIG_DFL; |
1931 | |
1932 | break; /* will return non-zero "signr" value */ |
1933 | } |
1934 | |
1935 | /* |
1936 | * Now we are doing the default action for this signal. |
1937 | */ |
1938 | if (sig_kernel_ignore(signr)) /* Default is nothing. */ |
1939 | continue; |
1940 | |
1941 | /* |
1942 | * Global init gets no signals it doesn't want. |
1943 | * Container-init gets no signals it doesn't want from same |
1944 | * container. |
1945 | * |
1946 | * Note that if global/container-init sees a sig_kernel_only() |
1947 | * signal here, the signal must have been generated internally |
1948 | * or must have come from an ancestor namespace. In either |
1949 | * case, the signal cannot be dropped. |
1950 | */ |
1951 | if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && |
1952 | !sig_kernel_only(signr)) |
1953 | continue; |
1954 | |
1955 | if (sig_kernel_stop(signr)) { |
1956 | /* |
1957 | * The default action is to stop all threads in |
1958 | * the thread group. The job control signals |
1959 | * do nothing in an orphaned pgrp, but SIGSTOP |
1960 | * always works. Note that siglock needs to be |
1961 | * dropped during the call to is_orphaned_pgrp() |
1962 | * because of lock ordering with tasklist_lock. |
1963 | * This allows an intervening SIGCONT to be posted. |
1964 | * We need to check for that and bail out if necessary. |
1965 | */ |
1966 | if (signr != SIGSTOP) { |
1967 | spin_unlock_irq(&sighand->siglock); |
1968 | |
1969 | /* signals can be posted during this window */ |
1970 | |
1971 | if (is_current_pgrp_orphaned()) |
1972 | goto relock; |
1973 | |
1974 | spin_lock_irq(&sighand->siglock); |
1975 | } |
1976 | |
1977 | if (likely(do_signal_stop(info->si_signo))) { |
1978 | /* It released the siglock. */ |
1979 | goto relock; |
1980 | } |
1981 | |
1982 | /* |
1983 | * We didn't actually stop, due to a race |
1984 | * with SIGCONT or something like that. |
1985 | */ |
1986 | continue; |
1987 | } |
1988 | |
1989 | spin_unlock_irq(&sighand->siglock); |
1990 | |
1991 | /* |
1992 | * Anything else is fatal, maybe with a core dump. |
1993 | */ |
1994 | current->flags |= PF_SIGNALED; |
1995 | |
1996 | if (sig_kernel_coredump(signr)) { |
1997 | if (print_fatal_signals) |
1998 | print_fatal_signal(regs, info->si_signo); |
1999 | /* |
2000 | * If it was able to dump core, this kills all |
2001 | * other threads in the group and synchronizes with |
2002 | * their demise. If we lost the race with another |
2003 | * thread getting here, it set group_exit_code |
2004 | * first and our do_group_exit call below will use |
2005 | * that value and ignore the one we pass it. |
2006 | */ |
2007 | do_coredump(info->si_signo, info->si_signo, regs); |
2008 | } |
2009 | |
2010 | /* |
2011 | * Death signals, no core dump. |
2012 | */ |
2013 | do_group_exit(info->si_signo); |
2014 | /* NOTREACHED */ |
2015 | } |
2016 | spin_unlock_irq(&sighand->siglock); |
2017 | return signr; |
2018 | } |
2019 | |
2020 | void exit_signals(struct task_struct *tsk) |
2021 | { |
2022 | int group_stop = 0; |
2023 | struct task_struct *t; |
2024 | |
2025 | if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { |
2026 | tsk->flags |= PF_EXITING; |
2027 | return; |
2028 | } |
2029 | |
2030 | spin_lock_irq(&tsk->sighand->siglock); |
2031 | /* |
2032 | * From now this task is not visible for group-wide signals, |
2033 | * see wants_signal(), do_signal_stop(). |
2034 | */ |
2035 | tsk->flags |= PF_EXITING; |
2036 | if (!signal_pending(tsk)) |
2037 | goto out; |
2038 | |
2039 | /* |
2040 | * It could be that __group_complete_signal() choose us to |
2041 | * notify about group-wide signal. Another thread should be |
2042 | * woken now to take the signal since we will not. |
2043 | */ |
2044 | for (t = tsk; (t = next_thread(t)) != tsk; ) |
2045 | if (!signal_pending(t) && !(t->flags & PF_EXITING)) |
2046 | recalc_sigpending_and_wake(t); |
2047 | |
2048 | if (unlikely(tsk->signal->group_stop_count) && |
2049 | !--tsk->signal->group_stop_count) { |
2050 | tsk->signal->flags = SIGNAL_STOP_STOPPED; |
2051 | group_stop = tracehook_notify_jctl(CLD_STOPPED, CLD_STOPPED); |
2052 | } |
2053 | out: |
2054 | spin_unlock_irq(&tsk->sighand->siglock); |
2055 | |
2056 | if (unlikely(group_stop)) { |
2057 | read_lock(&tasklist_lock); |
2058 | do_notify_parent_cldstop(tsk, group_stop); |
2059 | read_unlock(&tasklist_lock); |
2060 | } |
2061 | } |
2062 | |
2063 | EXPORT_SYMBOL(recalc_sigpending); |
2064 | EXPORT_SYMBOL_GPL(dequeue_signal); |
2065 | EXPORT_SYMBOL(flush_signals); |
2066 | EXPORT_SYMBOL(force_sig); |
2067 | EXPORT_SYMBOL(send_sig); |
2068 | EXPORT_SYMBOL(send_sig_info); |
2069 | EXPORT_SYMBOL(sigprocmask); |
2070 | EXPORT_SYMBOL(block_all_signals); |
2071 | EXPORT_SYMBOL(unblock_all_signals); |
2072 | |
2073 | |
2074 | /* |
2075 | * System call entry points. |
2076 | */ |
2077 | |
2078 | /** |
2079 | * sys_restart_syscall - restart a system call |
2080 | */ |
2081 | SYSCALL_DEFINE0(restart_syscall) |
2082 | { |
2083 | struct restart_block *restart = ¤t_thread_info()->restart_block; |
2084 | return restart->fn(restart); |
2085 | } |
2086 | |
2087 | long do_no_restart_syscall(struct restart_block *param) |
2088 | { |
2089 | return -EINTR; |
2090 | } |
2091 | |
2092 | /* |
2093 | * We don't need to get the kernel lock - this is all local to this |
2094 | * particular thread.. (and that's good, because this is _heavily_ |
2095 | * used by various programs) |
2096 | */ |
2097 | |
2098 | /* |
2099 | * This is also useful for kernel threads that want to temporarily |
2100 | * (or permanently) block certain signals. |
2101 | * |
2102 | * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel |
2103 | * interface happily blocks "unblockable" signals like SIGKILL |
2104 | * and friends. |
2105 | */ |
2106 | int sigprocmask(int how, sigset_t *set, sigset_t *oldset) |
2107 | { |
2108 | int error; |
2109 | |
2110 | spin_lock_irq(¤t->sighand->siglock); |
2111 | if (oldset) |
2112 | *oldset = current->blocked; |
2113 | |
2114 | error = 0; |
2115 | switch (how) { |
2116 | case SIG_BLOCK: |
2117 | sigorsets(¤t->blocked, ¤t->blocked, set); |
2118 | break; |
2119 | case SIG_UNBLOCK: |
2120 | signandsets(¤t->blocked, ¤t->blocked, set); |
2121 | break; |
2122 | case SIG_SETMASK: |
2123 | current->blocked = *set; |
2124 | break; |
2125 | default: |
2126 | error = -EINVAL; |
2127 | } |
2128 | recalc_sigpending(); |
2129 | spin_unlock_irq(¤t->sighand->siglock); |
2130 | |
2131 | return error; |
2132 | } |
2133 | |
2134 | /** |
2135 | * sys_rt_sigprocmask - change the list of currently blocked signals |
2136 | * @how: whether to add, remove, or set signals |
2137 | * @set: stores pending signals |
2138 | * @oset: previous value of signal mask if non-null |
2139 | * @sigsetsize: size of sigset_t type |
2140 | */ |
2141 | SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, set, |
2142 | sigset_t __user *, oset, size_t, sigsetsize) |
2143 | { |
2144 | int error = -EINVAL; |
2145 | sigset_t old_set, new_set; |
2146 | |
2147 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
2148 | if (sigsetsize != sizeof(sigset_t)) |
2149 | goto out; |
2150 | |
2151 | if (set) { |
2152 | error = -EFAULT; |
2153 | if (copy_from_user(&new_set, set, sizeof(*set))) |
2154 | goto out; |
2155 | sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
2156 | |
2157 | error = sigprocmask(how, &new_set, &old_set); |
2158 | if (error) |
2159 | goto out; |
2160 | if (oset) |
2161 | goto set_old; |
2162 | } else if (oset) { |
2163 | spin_lock_irq(¤t->sighand->siglock); |
2164 | old_set = current->blocked; |
2165 | spin_unlock_irq(¤t->sighand->siglock); |
2166 | |
2167 | set_old: |
2168 | error = -EFAULT; |
2169 | if (copy_to_user(oset, &old_set, sizeof(*oset))) |
2170 | goto out; |
2171 | } |
2172 | error = 0; |
2173 | out: |
2174 | return error; |
2175 | } |
2176 | |
2177 | long do_sigpending(void __user *set, unsigned long sigsetsize) |
2178 | { |
2179 | long error = -EINVAL; |
2180 | sigset_t pending; |
2181 | |
2182 | if (sigsetsize > sizeof(sigset_t)) |
2183 | goto out; |
2184 | |
2185 | spin_lock_irq(¤t->sighand->siglock); |
2186 | sigorsets(&pending, ¤t->pending.signal, |
2187 | ¤t->signal->shared_pending.signal); |
2188 | spin_unlock_irq(¤t->sighand->siglock); |
2189 | |
2190 | /* Outside the lock because only this thread touches it. */ |
2191 | sigandsets(&pending, ¤t->blocked, &pending); |
2192 | |
2193 | error = -EFAULT; |
2194 | if (!copy_to_user(set, &pending, sigsetsize)) |
2195 | error = 0; |
2196 | |
2197 | out: |
2198 | return error; |
2199 | } |
2200 | |
2201 | /** |
2202 | * sys_rt_sigpending - examine a pending signal that has been raised |
2203 | * while blocked |
2204 | * @set: stores pending signals |
2205 | * @sigsetsize: size of sigset_t type or larger |
2206 | */ |
2207 | SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize) |
2208 | { |
2209 | return do_sigpending(set, sigsetsize); |
2210 | } |
2211 | |
2212 | #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER |
2213 | |
2214 | int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) |
2215 | { |
2216 | int err; |
2217 | |
2218 | if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t))) |
2219 | return -EFAULT; |
2220 | if (from->si_code < 0) |
2221 | return __copy_to_user(to, from, sizeof(siginfo_t)) |
2222 | ? -EFAULT : 0; |
2223 | /* |
2224 | * If you change siginfo_t structure, please be sure |
2225 | * this code is fixed accordingly. |
2226 | * Please remember to update the signalfd_copyinfo() function |
2227 | * inside fs/signalfd.c too, in case siginfo_t changes. |
2228 | * It should never copy any pad contained in the structure |
2229 | * to avoid security leaks, but must copy the generic |
2230 | * 3 ints plus the relevant union member. |
2231 | */ |
2232 | err = __put_user(from->si_signo, &to->si_signo); |
2233 | err |= __put_user(from->si_errno, &to->si_errno); |
2234 | err |= __put_user((short)from->si_code, &to->si_code); |
2235 | switch (from->si_code & __SI_MASK) { |
2236 | case __SI_KILL: |
2237 | err |= __put_user(from->si_pid, &to->si_pid); |
2238 | err |= __put_user(from->si_uid, &to->si_uid); |
2239 | break; |
2240 | case __SI_TIMER: |
2241 | err |= __put_user(from->si_tid, &to->si_tid); |
2242 | err |= __put_user(from->si_overrun, &to->si_overrun); |
2243 | err |= __put_user(from->si_ptr, &to->si_ptr); |
2244 | break; |
2245 | case __SI_POLL: |
2246 | err |= __put_user(from->si_band, &to->si_band); |
2247 | err |= __put_user(from->si_fd, &to->si_fd); |
2248 | break; |
2249 | case __SI_FAULT: |
2250 | err |= __put_user(from->si_addr, &to->si_addr); |
2251 | #ifdef __ARCH_SI_TRAPNO |
2252 | err |= __put_user(from->si_trapno, &to->si_trapno); |
2253 | #endif |
2254 | #ifdef BUS_MCEERR_AO |
2255 | /* |
2256 | * Other callers might not initialize the si_lsb field, |
2257 | * so check explicitly for the right codes here. |
2258 | */ |
2259 | if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO) |
2260 | err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb); |
2261 | #endif |
2262 | break; |
2263 | case __SI_CHLD: |
2264 | err |= __put_user(from->si_pid, &to->si_pid); |
2265 | err |= __put_user(from->si_uid, &to->si_uid); |
2266 | err |= __put_user(from->si_status, &to->si_status); |
2267 | err |= __put_user(from->si_utime, &to->si_utime); |
2268 | err |= __put_user(from->si_stime, &to->si_stime); |
2269 | break; |
2270 | case __SI_RT: /* This is not generated by the kernel as of now. */ |
2271 | case __SI_MESGQ: /* But this is */ |
2272 | err |= __put_user(from->si_pid, &to->si_pid); |
2273 | err |= __put_user(from->si_uid, &to->si_uid); |
2274 | err |= __put_user(from->si_ptr, &to->si_ptr); |
2275 | break; |
2276 | default: /* this is just in case for now ... */ |
2277 | err |= __put_user(from->si_pid, &to->si_pid); |
2278 | err |= __put_user(from->si_uid, &to->si_uid); |
2279 | break; |
2280 | } |
2281 | return err; |
2282 | } |
2283 | |
2284 | #endif |
2285 | |
2286 | /** |
2287 | * sys_rt_sigtimedwait - synchronously wait for queued signals specified |
2288 | * in @uthese |
2289 | * @uthese: queued signals to wait for |
2290 | * @uinfo: if non-null, the signal's siginfo is returned here |
2291 | * @uts: upper bound on process time suspension |
2292 | * @sigsetsize: size of sigset_t type |
2293 | */ |
2294 | SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, |
2295 | siginfo_t __user *, uinfo, const struct timespec __user *, uts, |
2296 | size_t, sigsetsize) |
2297 | { |
2298 | int ret, sig; |
2299 | sigset_t these; |
2300 | struct timespec ts; |
2301 | siginfo_t info; |
2302 | long timeout = 0; |
2303 | |
2304 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
2305 | if (sigsetsize != sizeof(sigset_t)) |
2306 | return -EINVAL; |
2307 | |
2308 | if (copy_from_user(&these, uthese, sizeof(these))) |
2309 | return -EFAULT; |
2310 | |
2311 | /* |
2312 | * Invert the set of allowed signals to get those we |
2313 | * want to block. |
2314 | */ |
2315 | sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
2316 | signotset(&these); |
2317 | |
2318 | if (uts) { |
2319 | if (copy_from_user(&ts, uts, sizeof(ts))) |
2320 | return -EFAULT; |
2321 | if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0 |
2322 | || ts.tv_sec < 0) |
2323 | return -EINVAL; |
2324 | } |
2325 | |
2326 | spin_lock_irq(¤t->sighand->siglock); |
2327 | sig = dequeue_signal(current, &these, &info); |
2328 | if (!sig) { |
2329 | timeout = MAX_SCHEDULE_TIMEOUT; |
2330 | if (uts) |
2331 | timeout = (timespec_to_jiffies(&ts) |
2332 | + (ts.tv_sec || ts.tv_nsec)); |
2333 | |
2334 | if (timeout) { |
2335 | /* |
2336 | * None ready -- temporarily unblock those we're |
2337 | * interested while we are sleeping in so that we'll |
2338 | * be awakened when they arrive. |
2339 | */ |
2340 | current->real_blocked = current->blocked; |
2341 | sigandsets(¤t->blocked, ¤t->blocked, &these); |
2342 | recalc_sigpending(); |
2343 | spin_unlock_irq(¤t->sighand->siglock); |
2344 | |
2345 | timeout = schedule_timeout_interruptible(timeout); |
2346 | |
2347 | spin_lock_irq(¤t->sighand->siglock); |
2348 | sig = dequeue_signal(current, &these, &info); |
2349 | current->blocked = current->real_blocked; |
2350 | siginitset(¤t->real_blocked, 0); |
2351 | recalc_sigpending(); |
2352 | } |
2353 | } |
2354 | spin_unlock_irq(¤t->sighand->siglock); |
2355 | |
2356 | if (sig) { |
2357 | ret = sig; |
2358 | if (uinfo) { |
2359 | if (copy_siginfo_to_user(uinfo, &info)) |
2360 | ret = -EFAULT; |
2361 | } |
2362 | } else { |
2363 | ret = -EAGAIN; |
2364 | if (timeout) |
2365 | ret = -EINTR; |
2366 | } |
2367 | |
2368 | return ret; |
2369 | } |
2370 | |
2371 | /** |
2372 | * sys_kill - send a signal to a process |
2373 | * @pid: the PID of the process |
2374 | * @sig: signal to be sent |
2375 | */ |
2376 | SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) |
2377 | { |
2378 | struct siginfo info; |
2379 | |
2380 | info.si_signo = sig; |
2381 | info.si_errno = 0; |
2382 | info.si_code = SI_USER; |
2383 | info.si_pid = task_tgid_vnr(current); |
2384 | info.si_uid = current_uid(); |
2385 | |
2386 | return kill_something_info(sig, &info, pid); |
2387 | } |
2388 | |
2389 | static int |
2390 | do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info) |
2391 | { |
2392 | struct task_struct *p; |
2393 | int error = -ESRCH; |
2394 | |
2395 | rcu_read_lock(); |
2396 | p = find_task_by_vpid(pid); |
2397 | if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) { |
2398 | error = check_kill_permission(sig, info, p); |
2399 | /* |
2400 | * The null signal is a permissions and process existence |
2401 | * probe. No signal is actually delivered. |
2402 | */ |
2403 | if (!error && sig) { |
2404 | error = do_send_sig_info(sig, info, p, false); |
2405 | /* |
2406 | * If lock_task_sighand() failed we pretend the task |
2407 | * dies after receiving the signal. The window is tiny, |
2408 | * and the signal is private anyway. |
2409 | */ |
2410 | if (unlikely(error == -ESRCH)) |
2411 | error = 0; |
2412 | } |
2413 | } |
2414 | rcu_read_unlock(); |
2415 | |
2416 | return error; |
2417 | } |
2418 | |
2419 | static int do_tkill(pid_t tgid, pid_t pid, int sig) |
2420 | { |
2421 | struct siginfo info; |
2422 | |
2423 | info.si_signo = sig; |
2424 | info.si_errno = 0; |
2425 | info.si_code = SI_TKILL; |
2426 | info.si_pid = task_tgid_vnr(current); |
2427 | info.si_uid = current_uid(); |
2428 | |
2429 | return do_send_specific(tgid, pid, sig, &info); |
2430 | } |
2431 | |
2432 | /** |
2433 | * sys_tgkill - send signal to one specific thread |
2434 | * @tgid: the thread group ID of the thread |
2435 | * @pid: the PID of the thread |
2436 | * @sig: signal to be sent |
2437 | * |
2438 | * This syscall also checks the @tgid and returns -ESRCH even if the PID |
2439 | * exists but it's not belonging to the target process anymore. This |
2440 | * method solves the problem of threads exiting and PIDs getting reused. |
2441 | */ |
2442 | SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig) |
2443 | { |
2444 | /* This is only valid for single tasks */ |
2445 | if (pid <= 0 || tgid <= 0) |
2446 | return -EINVAL; |
2447 | |
2448 | return do_tkill(tgid, pid, sig); |
2449 | } |
2450 | |
2451 | /** |
2452 | * sys_tkill - send signal to one specific task |
2453 | * @pid: the PID of the task |
2454 | * @sig: signal to be sent |
2455 | * |
2456 | * Send a signal to only one task, even if it's a CLONE_THREAD task. |
2457 | */ |
2458 | SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) |
2459 | { |
2460 | /* This is only valid for single tasks */ |
2461 | if (pid <= 0) |
2462 | return -EINVAL; |
2463 | |
2464 | return do_tkill(0, pid, sig); |
2465 | } |
2466 | |
2467 | /** |
2468 | * sys_rt_sigqueueinfo - send signal information to a signal |
2469 | * @pid: the PID of the thread |
2470 | * @sig: signal to be sent |
2471 | * @uinfo: signal info to be sent |
2472 | */ |
2473 | SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, |
2474 | siginfo_t __user *, uinfo) |
2475 | { |
2476 | siginfo_t info; |
2477 | |
2478 | if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) |
2479 | return -EFAULT; |
2480 | |
2481 | /* Not even root can pretend to send signals from the kernel. |
2482 | * Nor can they impersonate a kill()/tgkill(), which adds source info. |
2483 | */ |
2484 | if (info.si_code >= 0 || info.si_code == SI_TKILL) { |
2485 | /* We used to allow any < 0 si_code */ |
2486 | WARN_ON_ONCE(info.si_code < 0); |
2487 | return -EPERM; |
2488 | } |
2489 | info.si_signo = sig; |
2490 | |
2491 | /* POSIX.1b doesn't mention process groups. */ |
2492 | return kill_proc_info(sig, &info, pid); |
2493 | } |
2494 | |
2495 | long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info) |
2496 | { |
2497 | /* This is only valid for single tasks */ |
2498 | if (pid <= 0 || tgid <= 0) |
2499 | return -EINVAL; |
2500 | |
2501 | /* Not even root can pretend to send signals from the kernel. |
2502 | * Nor can they impersonate a kill()/tgkill(), which adds source info. |
2503 | */ |
2504 | if (info->si_code >= 0 || info->si_code == SI_TKILL) { |
2505 | /* We used to allow any < 0 si_code */ |
2506 | WARN_ON_ONCE(info->si_code < 0); |
2507 | return -EPERM; |
2508 | } |
2509 | info->si_signo = sig; |
2510 | |
2511 | return do_send_specific(tgid, pid, sig, info); |
2512 | } |
2513 | |
2514 | SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig, |
2515 | siginfo_t __user *, uinfo) |
2516 | { |
2517 | siginfo_t info; |
2518 | |
2519 | if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) |
2520 | return -EFAULT; |
2521 | |
2522 | return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); |
2523 | } |
2524 | |
2525 | int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) |
2526 | { |
2527 | struct task_struct *t = current; |
2528 | struct k_sigaction *k; |
2529 | sigset_t mask; |
2530 | |
2531 | if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) |
2532 | return -EINVAL; |
2533 | |
2534 | k = &t->sighand->action[sig-1]; |
2535 | |
2536 | spin_lock_irq(¤t->sighand->siglock); |
2537 | if (oact) |
2538 | *oact = *k; |
2539 | |
2540 | if (act) { |
2541 | sigdelsetmask(&act->sa.sa_mask, |
2542 | sigmask(SIGKILL) | sigmask(SIGSTOP)); |
2543 | *k = *act; |
2544 | /* |
2545 | * POSIX 3.3.1.3: |
2546 | * "Setting a signal action to SIG_IGN for a signal that is |
2547 | * pending shall cause the pending signal to be discarded, |
2548 | * whether or not it is blocked." |
2549 | * |
2550 | * "Setting a signal action to SIG_DFL for a signal that is |
2551 | * pending and whose default action is to ignore the signal |
2552 | * (for example, SIGCHLD), shall cause the pending signal to |
2553 | * be discarded, whether or not it is blocked" |
2554 | */ |
2555 | if (sig_handler_ignored(sig_handler(t, sig), sig)) { |
2556 | sigemptyset(&mask); |
2557 | sigaddset(&mask, sig); |
2558 | rm_from_queue_full(&mask, &t->signal->shared_pending); |
2559 | do { |
2560 | rm_from_queue_full(&mask, &t->pending); |
2561 | t = next_thread(t); |
2562 | } while (t != current); |
2563 | } |
2564 | } |
2565 | |
2566 | spin_unlock_irq(¤t->sighand->siglock); |
2567 | return 0; |
2568 | } |
2569 | |
2570 | int |
2571 | do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp) |
2572 | { |
2573 | stack_t oss; |
2574 | int error; |
2575 | |
2576 | oss.ss_sp = (void __user *) current->sas_ss_sp; |
2577 | oss.ss_size = current->sas_ss_size; |
2578 | oss.ss_flags = sas_ss_flags(sp); |
2579 | |
2580 | if (uss) { |
2581 | void __user *ss_sp; |
2582 | size_t ss_size; |
2583 | int ss_flags; |
2584 | |
2585 | error = -EFAULT; |
2586 | if (!access_ok(VERIFY_READ, uss, sizeof(*uss))) |
2587 | goto out; |
2588 | error = __get_user(ss_sp, &uss->ss_sp) | |
2589 | __get_user(ss_flags, &uss->ss_flags) | |
2590 | __get_user(ss_size, &uss->ss_size); |
2591 | if (error) |
2592 | goto out; |
2593 | |
2594 | error = -EPERM; |
2595 | if (on_sig_stack(sp)) |
2596 | goto out; |
2597 | |
2598 | error = -EINVAL; |
2599 | /* |
2600 | * Note - this code used to test ss_flags incorrectly: |
2601 | * old code may have been written using ss_flags==0 |
2602 | * to mean ss_flags==SS_ONSTACK (as this was the only |
2603 | * way that worked) - this fix preserves that older |
2604 | * mechanism. |
2605 | */ |
2606 | if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0) |
2607 | goto out; |
2608 | |
2609 | if (ss_flags == SS_DISABLE) { |
2610 | ss_size = 0; |
2611 | ss_sp = NULL; |
2612 | } else { |
2613 | error = -ENOMEM; |
2614 | if (ss_size < MINSIGSTKSZ) |
2615 | goto out; |
2616 | } |
2617 | |
2618 | current->sas_ss_sp = (unsigned long) ss_sp; |
2619 | current->sas_ss_size = ss_size; |
2620 | } |
2621 | |
2622 | error = 0; |
2623 | if (uoss) { |
2624 | error = -EFAULT; |
2625 | if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss))) |
2626 | goto out; |
2627 | error = __put_user(oss.ss_sp, &uoss->ss_sp) | |
2628 | __put_user(oss.ss_size, &uoss->ss_size) | |
2629 | __put_user(oss.ss_flags, &uoss->ss_flags); |
2630 | } |
2631 | |
2632 | out: |
2633 | return error; |
2634 | } |
2635 | |
2636 | #ifdef __ARCH_WANT_SYS_SIGPENDING |
2637 | |
2638 | /** |
2639 | * sys_sigpending - examine pending signals |
2640 | * @set: where mask of pending signal is returned |
2641 | */ |
2642 | SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) |
2643 | { |
2644 | return do_sigpending(set, sizeof(*set)); |
2645 | } |
2646 | |
2647 | #endif |
2648 | |
2649 | #ifdef __ARCH_WANT_SYS_SIGPROCMASK |
2650 | /** |
2651 | * sys_sigprocmask - examine and change blocked signals |
2652 | * @how: whether to add, remove, or set signals |
2653 | * @set: signals to add or remove (if non-null) |
2654 | * @oset: previous value of signal mask if non-null |
2655 | * |
2656 | * Some platforms have their own version with special arguments; |
2657 | * others support only sys_rt_sigprocmask. |
2658 | */ |
2659 | |
2660 | SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, set, |
2661 | old_sigset_t __user *, oset) |
2662 | { |
2663 | int error; |
2664 | old_sigset_t old_set, new_set; |
2665 | |
2666 | if (set) { |
2667 | error = -EFAULT; |
2668 | if (copy_from_user(&new_set, set, sizeof(*set))) |
2669 | goto out; |
2670 | new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP)); |
2671 | |
2672 | spin_lock_irq(¤t->sighand->siglock); |
2673 | old_set = current->blocked.sig[0]; |
2674 | |
2675 | error = 0; |
2676 | switch (how) { |
2677 | default: |
2678 | error = -EINVAL; |
2679 | break; |
2680 | case SIG_BLOCK: |
2681 | sigaddsetmask(¤t->blocked, new_set); |
2682 | break; |
2683 | case SIG_UNBLOCK: |
2684 | sigdelsetmask(¤t->blocked, new_set); |
2685 | break; |
2686 | case SIG_SETMASK: |
2687 | current->blocked.sig[0] = new_set; |
2688 | break; |
2689 | } |
2690 | |
2691 | recalc_sigpending(); |
2692 | spin_unlock_irq(¤t->sighand->siglock); |
2693 | if (error) |
2694 | goto out; |
2695 | if (oset) |
2696 | goto set_old; |
2697 | } else if (oset) { |
2698 | old_set = current->blocked.sig[0]; |
2699 | set_old: |
2700 | error = -EFAULT; |
2701 | if (copy_to_user(oset, &old_set, sizeof(*oset))) |
2702 | goto out; |
2703 | } |
2704 | error = 0; |
2705 | out: |
2706 | return error; |
2707 | } |
2708 | #endif /* __ARCH_WANT_SYS_SIGPROCMASK */ |
2709 | |
2710 | #ifdef __ARCH_WANT_SYS_RT_SIGACTION |
2711 | /** |
2712 | * sys_rt_sigaction - alter an action taken by a process |
2713 | * @sig: signal to be sent |
2714 | * @act: new sigaction |
2715 | * @oact: used to save the previous sigaction |
2716 | * @sigsetsize: size of sigset_t type |
2717 | */ |
2718 | SYSCALL_DEFINE4(rt_sigaction, int, sig, |
2719 | const struct sigaction __user *, act, |
2720 | struct sigaction __user *, oact, |
2721 | size_t, sigsetsize) |
2722 | { |
2723 | struct k_sigaction new_sa, old_sa; |
2724 | int ret = -EINVAL; |
2725 | |
2726 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
2727 | if (sigsetsize != sizeof(sigset_t)) |
2728 | goto out; |
2729 | |
2730 | if (act) { |
2731 | if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa))) |
2732 | return -EFAULT; |
2733 | } |
2734 | |
2735 | ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL); |
2736 | |
2737 | if (!ret && oact) { |
2738 | if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa))) |
2739 | return -EFAULT; |
2740 | } |
2741 | out: |
2742 | return ret; |
2743 | } |
2744 | #endif /* __ARCH_WANT_SYS_RT_SIGACTION */ |
2745 | |
2746 | #ifdef __ARCH_WANT_SYS_SGETMASK |
2747 | |
2748 | /* |
2749 | * For backwards compatibility. Functionality superseded by sigprocmask. |
2750 | */ |
2751 | SYSCALL_DEFINE0(sgetmask) |
2752 | { |
2753 | /* SMP safe */ |
2754 | return current->blocked.sig[0]; |
2755 | } |
2756 | |
2757 | SYSCALL_DEFINE1(ssetmask, int, newmask) |
2758 | { |
2759 | int old; |
2760 | |
2761 | spin_lock_irq(¤t->sighand->siglock); |
2762 | old = current->blocked.sig[0]; |
2763 | |
2764 | siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)| |
2765 | sigmask(SIGSTOP))); |
2766 | recalc_sigpending(); |
2767 | spin_unlock_irq(¤t->sighand->siglock); |
2768 | |
2769 | return old; |
2770 | } |
2771 | #endif /* __ARCH_WANT_SGETMASK */ |
2772 | |
2773 | #ifdef __ARCH_WANT_SYS_SIGNAL |
2774 | /* |
2775 | * For backwards compatibility. Functionality superseded by sigaction. |
2776 | */ |
2777 | SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler) |
2778 | { |
2779 | struct k_sigaction new_sa, old_sa; |
2780 | int ret; |
2781 | |
2782 | new_sa.sa.sa_handler = handler; |
2783 | new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK; |
2784 | sigemptyset(&new_sa.sa.sa_mask); |
2785 | |
2786 | ret = do_sigaction(sig, &new_sa, &old_sa); |
2787 | |
2788 | return ret ? ret : (unsigned long)old_sa.sa.sa_handler; |
2789 | } |
2790 | #endif /* __ARCH_WANT_SYS_SIGNAL */ |
2791 | |
2792 | #ifdef __ARCH_WANT_SYS_PAUSE |
2793 | |
2794 | SYSCALL_DEFINE0(pause) |
2795 | { |
2796 | current->state = TASK_INTERRUPTIBLE; |
2797 | schedule(); |
2798 | return -ERESTARTNOHAND; |
2799 | } |
2800 | |
2801 | #endif |
2802 | |
2803 | #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND |
2804 | /** |
2805 | * sys_rt_sigsuspend - replace the signal mask for a value with the |
2806 | * @unewset value until a signal is received |
2807 | * @unewset: new signal mask value |
2808 | * @sigsetsize: size of sigset_t type |
2809 | */ |
2810 | SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize) |
2811 | { |
2812 | sigset_t newset; |
2813 | |
2814 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
2815 | if (sigsetsize != sizeof(sigset_t)) |
2816 | return -EINVAL; |
2817 | |
2818 | if (copy_from_user(&newset, unewset, sizeof(newset))) |
2819 | return -EFAULT; |
2820 | sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
2821 | |
2822 | spin_lock_irq(¤t->sighand->siglock); |
2823 | current->saved_sigmask = current->blocked; |
2824 | current->blocked = newset; |
2825 | recalc_sigpending(); |
2826 | spin_unlock_irq(¤t->sighand->siglock); |
2827 | |
2828 | current->state = TASK_INTERRUPTIBLE; |
2829 | schedule(); |
2830 | set_restore_sigmask(); |
2831 | return -ERESTARTNOHAND; |
2832 | } |
2833 | #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */ |
2834 | |
2835 | __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma) |
2836 | { |
2837 | return NULL; |
2838 | } |
2839 | |
2840 | void __init signals_init(void) |
2841 | { |
2842 | sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); |
2843 | } |
2844 | |
2845 | #ifdef CONFIG_KGDB_KDB |
2846 | #include <linux/kdb.h> |
2847 | /* |
2848 | * kdb_send_sig_info - Allows kdb to send signals without exposing |
2849 | * signal internals. This function checks if the required locks are |
2850 | * available before calling the main signal code, to avoid kdb |
2851 | * deadlocks. |
2852 | */ |
2853 | void |
2854 | kdb_send_sig_info(struct task_struct *t, struct siginfo *info) |
2855 | { |
2856 | static struct task_struct *kdb_prev_t; |
2857 | int sig, new_t; |
2858 | if (!spin_trylock(&t->sighand->siglock)) { |
2859 | kdb_printf("Can't do kill command now.\n" |
2860 | "The sigmask lock is held somewhere else in " |
2861 | "kernel, try again later\n"); |
2862 | return; |
2863 | } |
2864 | spin_unlock(&t->sighand->siglock); |
2865 | new_t = kdb_prev_t != t; |
2866 | kdb_prev_t = t; |
2867 | if (t->state != TASK_RUNNING && new_t) { |
2868 | kdb_printf("Process is not RUNNING, sending a signal from " |
2869 | "kdb risks deadlock\n" |
2870 | "on the run queue locks. " |
2871 | "The signal has _not_ been sent.\n" |
2872 | "Reissue the kill command if you want to risk " |
2873 | "the deadlock.\n"); |
2874 | return; |
2875 | } |
2876 | sig = info->si_signo; |
2877 | if (send_sig_info(sig, info, t)) |
2878 | kdb_printf("Fail to deliver Signal %d to process %d.\n", |
2879 | sig, t->pid); |
2880 | else |
2881 | kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid); |
2882 | } |
2883 | #endif /* CONFIG_KGDB_KDB */ |
2884 |
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