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Linux/kernel/signal.c

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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/export.h>
 15 #include <linux/init.h>
 16 #include <linux/sched.h>
 17 #include <linux/fs.h>
 18 #include <linux/tty.h>
 19 #include <linux/binfmts.h>
 20 #include <linux/coredump.h>
 21 #include <linux/security.h>
 22 #include <linux/syscalls.h>
 23 #include <linux/ptrace.h>
 24 #include <linux/signal.h>
 25 #include <linux/signalfd.h>
 26 #include <linux/ratelimit.h>
 27 #include <linux/tracehook.h>
 28 #include <linux/capability.h>
 29 #include <linux/freezer.h>
 30 #include <linux/pid_namespace.h>
 31 #include <linux/nsproxy.h>
 32 #include <linux/user_namespace.h>
 33 #include <linux/uprobes.h>
 34 #include <linux/compat.h>
 35 #include <linux/cn_proc.h>
 36 #include <linux/compiler.h>
 37 
 38 #define CREATE_TRACE_POINTS
 39 #include <trace/events/signal.h>
 40 
 41 #include <asm/param.h>
 42 #include <asm/uaccess.h>
 43 #include <asm/unistd.h>
 44 #include <asm/siginfo.h>
 45 #include <asm/cacheflush.h>
 46 #include "audit.h"      /* audit_signal_info() */
 47 
 48 /*
 49  * SLAB caches for signal bits.
 50  */
 51 
 52 static struct kmem_cache *sigqueue_cachep;
 53 
 54 int print_fatal_signals __read_mostly;
 55 
 56 static void __user *sig_handler(struct task_struct *t, int sig)
 57 {
 58         return t->sighand->action[sig - 1].sa.sa_handler;
 59 }
 60 
 61 static int sig_handler_ignored(void __user *handler, int sig)
 62 {
 63         /* Is it explicitly or implicitly ignored? */
 64         return handler == SIG_IGN ||
 65                 (handler == SIG_DFL && sig_kernel_ignore(sig));
 66 }
 67 
 68 static int sig_task_ignored(struct task_struct *t, int sig, bool force)
 69 {
 70         void __user *handler;
 71 
 72         handler = sig_handler(t, sig);
 73 
 74         if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
 75                         handler == SIG_DFL && !force)
 76                 return 1;
 77 
 78         return sig_handler_ignored(handler, sig);
 79 }
 80 
 81 static int sig_ignored(struct task_struct *t, int sig, bool force)
 82 {
 83         /*
 84          * Blocked signals are never ignored, since the
 85          * signal handler may change by the time it is
 86          * unblocked.
 87          */
 88         if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
 89                 return 0;
 90 
 91         if (!sig_task_ignored(t, sig, force))
 92                 return 0;
 93 
 94         /*
 95          * Tracers may want to know about even ignored signals.
 96          */
 97         return !t->ptrace;
 98 }
 99 
100 /*
101  * Re-calculate pending state from the set of locally pending
102  * signals, globally pending signals, and blocked signals.
103  */
104 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
105 {
106         unsigned long ready;
107         long i;
108 
109         switch (_NSIG_WORDS) {
110         default:
111                 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
112                         ready |= signal->sig[i] &~ blocked->sig[i];
113                 break;
114 
115         case 4: ready  = signal->sig[3] &~ blocked->sig[3];
116                 ready |= signal->sig[2] &~ blocked->sig[2];
117                 ready |= signal->sig[1] &~ blocked->sig[1];
118                 ready |= signal->sig[0] &~ blocked->sig[0];
119                 break;
120 
121         case 2: ready  = signal->sig[1] &~ blocked->sig[1];
122                 ready |= signal->sig[0] &~ blocked->sig[0];
123                 break;
124 
125         case 1: ready  = signal->sig[0] &~ blocked->sig[0];
126         }
127         return ready != 0;
128 }
129 
130 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
131 
132 static int recalc_sigpending_tsk(struct task_struct *t)
133 {
134         if ((t->jobctl & JOBCTL_PENDING_MASK) ||
135             PENDING(&t->pending, &t->blocked) ||
136             PENDING(&t->signal->shared_pending, &t->blocked)) {
137                 set_tsk_thread_flag(t, TIF_SIGPENDING);
138                 return 1;
139         }
140         /*
141          * We must never clear the flag in another thread, or in current
142          * when it's possible the current syscall is returning -ERESTART*.
143          * So we don't clear it here, and only callers who know they should do.
144          */
145         return 0;
146 }
147 
148 /*
149  * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
150  * This is superfluous when called on current, the wakeup is a harmless no-op.
151  */
152 void recalc_sigpending_and_wake(struct task_struct *t)
153 {
154         if (recalc_sigpending_tsk(t))
155                 signal_wake_up(t, 0);
156 }
157 
158 void recalc_sigpending(void)
159 {
160         if (!recalc_sigpending_tsk(current) && !freezing(current))
161                 clear_thread_flag(TIF_SIGPENDING);
162 
163 }
164 
165 /* Given the mask, find the first available signal that should be serviced. */
166 
167 #define SYNCHRONOUS_MASK \
168         (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
169          sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
170 
171 int next_signal(struct sigpending *pending, sigset_t *mask)
172 {
173         unsigned long i, *s, *m, x;
174         int sig = 0;
175 
176         s = pending->signal.sig;
177         m = mask->sig;
178 
179         /*
180          * Handle the first word specially: it contains the
181          * synchronous signals that need to be dequeued first.
182          */
183         x = *s &~ *m;
184         if (x) {
185                 if (x & SYNCHRONOUS_MASK)
186                         x &= SYNCHRONOUS_MASK;
187                 sig = ffz(~x) + 1;
188                 return sig;
189         }
190 
191         switch (_NSIG_WORDS) {
192         default:
193                 for (i = 1; i < _NSIG_WORDS; ++i) {
194                         x = *++s &~ *++m;
195                         if (!x)
196                                 continue;
197                         sig = ffz(~x) + i*_NSIG_BPW + 1;
198                         break;
199                 }
200                 break;
201 
202         case 2:
203                 x = s[1] &~ m[1];
204                 if (!x)
205                         break;
206                 sig = ffz(~x) + _NSIG_BPW + 1;
207                 break;
208 
209         case 1:
210                 /* Nothing to do */
211                 break;
212         }
213 
214         return sig;
215 }
216 
217 static inline void print_dropped_signal(int sig)
218 {
219         static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
220 
221         if (!print_fatal_signals)
222                 return;
223 
224         if (!__ratelimit(&ratelimit_state))
225                 return;
226 
227         printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
228                                 current->comm, current->pid, sig);
229 }
230 
231 /**
232  * task_set_jobctl_pending - set jobctl pending bits
233  * @task: target task
234  * @mask: pending bits to set
235  *
236  * Clear @mask from @task->jobctl.  @mask must be subset of
237  * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
238  * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
239  * cleared.  If @task is already being killed or exiting, this function
240  * becomes noop.
241  *
242  * CONTEXT:
243  * Must be called with @task->sighand->siglock held.
244  *
245  * RETURNS:
246  * %true if @mask is set, %false if made noop because @task was dying.
247  */
248 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
249 {
250         BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
251                         JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
252         BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
253 
254         if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
255                 return false;
256 
257         if (mask & JOBCTL_STOP_SIGMASK)
258                 task->jobctl &= ~JOBCTL_STOP_SIGMASK;
259 
260         task->jobctl |= mask;
261         return true;
262 }
263 
264 /**
265  * task_clear_jobctl_trapping - clear jobctl trapping bit
266  * @task: target task
267  *
268  * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
269  * Clear it and wake up the ptracer.  Note that we don't need any further
270  * locking.  @task->siglock guarantees that @task->parent points to the
271  * ptracer.
272  *
273  * CONTEXT:
274  * Must be called with @task->sighand->siglock held.
275  */
276 void task_clear_jobctl_trapping(struct task_struct *task)
277 {
278         if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
279                 task->jobctl &= ~JOBCTL_TRAPPING;
280                 smp_mb();       /* advised by wake_up_bit() */
281                 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
282         }
283 }
284 
285 /**
286  * task_clear_jobctl_pending - clear jobctl pending bits
287  * @task: target task
288  * @mask: pending bits to clear
289  *
290  * Clear @mask from @task->jobctl.  @mask must be subset of
291  * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
292  * STOP bits are cleared together.
293  *
294  * If clearing of @mask leaves no stop or trap pending, this function calls
295  * task_clear_jobctl_trapping().
296  *
297  * CONTEXT:
298  * Must be called with @task->sighand->siglock held.
299  */
300 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
301 {
302         BUG_ON(mask & ~JOBCTL_PENDING_MASK);
303 
304         if (mask & JOBCTL_STOP_PENDING)
305                 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
306 
307         task->jobctl &= ~mask;
308 
309         if (!(task->jobctl & JOBCTL_PENDING_MASK))
310                 task_clear_jobctl_trapping(task);
311 }
312 
313 /**
314  * task_participate_group_stop - participate in a group stop
315  * @task: task participating in a group stop
316  *
317  * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
318  * Group stop states are cleared and the group stop count is consumed if
319  * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
320  * stop, the appropriate %SIGNAL_* flags are set.
321  *
322  * CONTEXT:
323  * Must be called with @task->sighand->siglock held.
324  *
325  * RETURNS:
326  * %true if group stop completion should be notified to the parent, %false
327  * otherwise.
328  */
329 static bool task_participate_group_stop(struct task_struct *task)
330 {
331         struct signal_struct *sig = task->signal;
332         bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
333 
334         WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
335 
336         task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
337 
338         if (!consume)
339                 return false;
340 
341         if (!WARN_ON_ONCE(sig->group_stop_count == 0))
342                 sig->group_stop_count--;
343 
344         /*
345          * Tell the caller to notify completion iff we are entering into a
346          * fresh group stop.  Read comment in do_signal_stop() for details.
347          */
348         if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
349                 sig->flags = SIGNAL_STOP_STOPPED;
350                 return true;
351         }
352         return false;
353 }
354 
355 /*
356  * allocate a new signal queue record
357  * - this may be called without locks if and only if t == current, otherwise an
358  *   appropriate lock must be held to stop the target task from exiting
359  */
360 static struct sigqueue *
361 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
362 {
363         struct sigqueue *q = NULL;
364         struct user_struct *user;
365 
366         /*
367          * Protect access to @t credentials. This can go away when all
368          * callers hold rcu read lock.
369          */
370         rcu_read_lock();
371         user = get_uid(__task_cred(t)->user);
372         atomic_inc(&user->sigpending);
373         rcu_read_unlock();
374 
375         if (override_rlimit ||
376             atomic_read(&user->sigpending) <=
377                         task_rlimit(t, RLIMIT_SIGPENDING)) {
378                 q = kmem_cache_alloc(sigqueue_cachep, flags);
379         } else {
380                 print_dropped_signal(sig);
381         }
382 
383         if (unlikely(q == NULL)) {
384                 atomic_dec(&user->sigpending);
385                 free_uid(user);
386         } else {
387                 INIT_LIST_HEAD(&q->list);
388                 q->flags = 0;
389                 q->user = user;
390         }
391 
392         return q;
393 }
394 
395 static void __sigqueue_free(struct sigqueue *q)
396 {
397         if (q->flags & SIGQUEUE_PREALLOC)
398                 return;
399         atomic_dec(&q->user->sigpending);
400         free_uid(q->user);
401         kmem_cache_free(sigqueue_cachep, q);
402 }
403 
404 void flush_sigqueue(struct sigpending *queue)
405 {
406         struct sigqueue *q;
407 
408         sigemptyset(&queue->signal);
409         while (!list_empty(&queue->list)) {
410                 q = list_entry(queue->list.next, struct sigqueue , list);
411                 list_del_init(&q->list);
412                 __sigqueue_free(q);
413         }
414 }
415 
416 /*
417  * Flush all pending signals for a task.
418  */
419 void __flush_signals(struct task_struct *t)
420 {
421         clear_tsk_thread_flag(t, TIF_SIGPENDING);
422         flush_sigqueue(&t->pending);
423         flush_sigqueue(&t->signal->shared_pending);
424 }
425 
426 void flush_signals(struct task_struct *t)
427 {
428         unsigned long flags;
429 
430         spin_lock_irqsave(&t->sighand->siglock, flags);
431         __flush_signals(t);
432         spin_unlock_irqrestore(&t->sighand->siglock, flags);
433 }
434 
435 static void __flush_itimer_signals(struct sigpending *pending)
436 {
437         sigset_t signal, retain;
438         struct sigqueue *q, *n;
439 
440         signal = pending->signal;
441         sigemptyset(&retain);
442 
443         list_for_each_entry_safe(q, n, &pending->list, list) {
444                 int sig = q->info.si_signo;
445 
446                 if (likely(q->info.si_code != SI_TIMER)) {
447                         sigaddset(&retain, sig);
448                 } else {
449                         sigdelset(&signal, sig);
450                         list_del_init(&q->list);
451                         __sigqueue_free(q);
452                 }
453         }
454 
455         sigorsets(&pending->signal, &signal, &retain);
456 }
457 
458 void flush_itimer_signals(void)
459 {
460         struct task_struct *tsk = current;
461         unsigned long flags;
462 
463         spin_lock_irqsave(&tsk->sighand->siglock, flags);
464         __flush_itimer_signals(&tsk->pending);
465         __flush_itimer_signals(&tsk->signal->shared_pending);
466         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
467 }
468 
469 void ignore_signals(struct task_struct *t)
470 {
471         int i;
472 
473         for (i = 0; i < _NSIG; ++i)
474                 t->sighand->action[i].sa.sa_handler = SIG_IGN;
475 
476         flush_signals(t);
477 }
478 
479 /*
480  * Flush all handlers for a task.
481  */
482 
483 void
484 flush_signal_handlers(struct task_struct *t, int force_default)
485 {
486         int i;
487         struct k_sigaction *ka = &t->sighand->action[0];
488         for (i = _NSIG ; i != 0 ; i--) {
489                 if (force_default || ka->sa.sa_handler != SIG_IGN)
490                         ka->sa.sa_handler = SIG_DFL;
491                 ka->sa.sa_flags = 0;
492 #ifdef __ARCH_HAS_SA_RESTORER
493                 ka->sa.sa_restorer = NULL;
494 #endif
495                 sigemptyset(&ka->sa.sa_mask);
496                 ka++;
497         }
498 }
499 
500 int unhandled_signal(struct task_struct *tsk, int sig)
501 {
502         void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
503         if (is_global_init(tsk))
504                 return 1;
505         if (handler != SIG_IGN && handler != SIG_DFL)
506                 return 0;
507         /* if ptraced, let the tracer determine */
508         return !tsk->ptrace;
509 }
510 
511 /*
512  * Notify the system that a driver wants to block all signals for this
513  * process, and wants to be notified if any signals at all were to be
514  * sent/acted upon.  If the notifier routine returns non-zero, then the
515  * signal will be acted upon after all.  If the notifier routine returns 0,
516  * then then signal will be blocked.  Only one block per process is
517  * allowed.  priv is a pointer to private data that the notifier routine
518  * can use to determine if the signal should be blocked or not.
519  */
520 void
521 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
522 {
523         unsigned long flags;
524 
525         spin_lock_irqsave(&current->sighand->siglock, flags);
526         current->notifier_mask = mask;
527         current->notifier_data = priv;
528         current->notifier = notifier;
529         spin_unlock_irqrestore(&current->sighand->siglock, flags);
530 }
531 
532 /* Notify the system that blocking has ended. */
533 
534 void
535 unblock_all_signals(void)
536 {
537         unsigned long flags;
538 
539         spin_lock_irqsave(&current->sighand->siglock, flags);
540         current->notifier = NULL;
541         current->notifier_data = NULL;
542         recalc_sigpending();
543         spin_unlock_irqrestore(&current->sighand->siglock, flags);
544 }
545 
546 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
547 {
548         struct sigqueue *q, *first = NULL;
549 
550         /*
551          * Collect the siginfo appropriate to this signal.  Check if
552          * there is another siginfo for the same signal.
553         */
554         list_for_each_entry(q, &list->list, list) {
555                 if (q->info.si_signo == sig) {
556                         if (first)
557                                 goto still_pending;
558                         first = q;
559                 }
560         }
561 
562         sigdelset(&list->signal, sig);
563 
564         if (first) {
565 still_pending:
566                 list_del_init(&first->list);
567                 copy_siginfo(info, &first->info);
568                 __sigqueue_free(first);
569         } else {
570                 /*
571                  * Ok, it wasn't in the queue.  This must be
572                  * a fast-pathed signal or we must have been
573                  * out of queue space.  So zero out the info.
574                  */
575                 info->si_signo = sig;
576                 info->si_errno = 0;
577                 info->si_code = SI_USER;
578                 info->si_pid = 0;
579                 info->si_uid = 0;
580         }
581 }
582 
583 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
584                         siginfo_t *info)
585 {
586         int sig = next_signal(pending, mask);
587 
588         if (sig) {
589                 if (current->notifier) {
590                         if (sigismember(current->notifier_mask, sig)) {
591                                 if (!(current->notifier)(current->notifier_data)) {
592                                         clear_thread_flag(TIF_SIGPENDING);
593                                         return 0;
594                                 }
595                         }
596                 }
597 
598                 collect_signal(sig, pending, info);
599         }
600 
601         return sig;
602 }
603 
604 /*
605  * Dequeue a signal and return the element to the caller, which is
606  * expected to free it.
607  *
608  * All callers have to hold the siglock.
609  */
610 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
611 {
612         int signr;
613 
614         /* We only dequeue private signals from ourselves, we don't let
615          * signalfd steal them
616          */
617         signr = __dequeue_signal(&tsk->pending, mask, info);
618         if (!signr) {
619                 signr = __dequeue_signal(&tsk->signal->shared_pending,
620                                          mask, info);
621                 /*
622                  * itimer signal ?
623                  *
624                  * itimers are process shared and we restart periodic
625                  * itimers in the signal delivery path to prevent DoS
626                  * attacks in the high resolution timer case. This is
627                  * compliant with the old way of self-restarting
628                  * itimers, as the SIGALRM is a legacy signal and only
629                  * queued once. Changing the restart behaviour to
630                  * restart the timer in the signal dequeue path is
631                  * reducing the timer noise on heavy loaded !highres
632                  * systems too.
633                  */
634                 if (unlikely(signr == SIGALRM)) {
635                         struct hrtimer *tmr = &tsk->signal->real_timer;
636 
637                         if (!hrtimer_is_queued(tmr) &&
638                             tsk->signal->it_real_incr.tv64 != 0) {
639                                 hrtimer_forward(tmr, tmr->base->get_time(),
640                                                 tsk->signal->it_real_incr);
641                                 hrtimer_restart(tmr);
642                         }
643                 }
644         }
645 
646         recalc_sigpending();
647         if (!signr)
648                 return 0;
649 
650         if (unlikely(sig_kernel_stop(signr))) {
651                 /*
652                  * Set a marker that we have dequeued a stop signal.  Our
653                  * caller might release the siglock and then the pending
654                  * stop signal it is about to process is no longer in the
655                  * pending bitmasks, but must still be cleared by a SIGCONT
656                  * (and overruled by a SIGKILL).  So those cases clear this
657                  * shared flag after we've set it.  Note that this flag may
658                  * remain set after the signal we return is ignored or
659                  * handled.  That doesn't matter because its only purpose
660                  * is to alert stop-signal processing code when another
661                  * processor has come along and cleared the flag.
662                  */
663                 current->jobctl |= JOBCTL_STOP_DEQUEUED;
664         }
665         if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
666                 /*
667                  * Release the siglock to ensure proper locking order
668                  * of timer locks outside of siglocks.  Note, we leave
669                  * irqs disabled here, since the posix-timers code is
670                  * about to disable them again anyway.
671                  */
672                 spin_unlock(&tsk->sighand->siglock);
673                 do_schedule_next_timer(info);
674                 spin_lock(&tsk->sighand->siglock);
675         }
676         return signr;
677 }
678 
679 /*
680  * Tell a process that it has a new active signal..
681  *
682  * NOTE! we rely on the previous spin_lock to
683  * lock interrupts for us! We can only be called with
684  * "siglock" held, and the local interrupt must
685  * have been disabled when that got acquired!
686  *
687  * No need to set need_resched since signal event passing
688  * goes through ->blocked
689  */
690 void signal_wake_up_state(struct task_struct *t, unsigned int state)
691 {
692         set_tsk_thread_flag(t, TIF_SIGPENDING);
693         /*
694          * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
695          * case. We don't check t->state here because there is a race with it
696          * executing another processor and just now entering stopped state.
697          * By using wake_up_state, we ensure the process will wake up and
698          * handle its death signal.
699          */
700         if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
701                 kick_process(t);
702 }
703 
704 /*
705  * Remove signals in mask from the pending set and queue.
706  * Returns 1 if any signals were found.
707  *
708  * All callers must be holding the siglock.
709  */
710 static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
711 {
712         struct sigqueue *q, *n;
713         sigset_t m;
714 
715         sigandsets(&m, mask, &s->signal);
716         if (sigisemptyset(&m))
717                 return 0;
718 
719         sigandnsets(&s->signal, &s->signal, mask);
720         list_for_each_entry_safe(q, n, &s->list, list) {
721                 if (sigismember(mask, q->info.si_signo)) {
722                         list_del_init(&q->list);
723                         __sigqueue_free(q);
724                 }
725         }
726         return 1;
727 }
728 
729 static inline int is_si_special(const struct siginfo *info)
730 {
731         return info <= SEND_SIG_FORCED;
732 }
733 
734 static inline bool si_fromuser(const struct siginfo *info)
735 {
736         return info == SEND_SIG_NOINFO ||
737                 (!is_si_special(info) && SI_FROMUSER(info));
738 }
739 
740 /*
741  * called with RCU read lock from check_kill_permission()
742  */
743 static int kill_ok_by_cred(struct task_struct *t)
744 {
745         const struct cred *cred = current_cred();
746         const struct cred *tcred = __task_cred(t);
747 
748         if (uid_eq(cred->euid, tcred->suid) ||
749             uid_eq(cred->euid, tcred->uid)  ||
750             uid_eq(cred->uid,  tcred->suid) ||
751             uid_eq(cred->uid,  tcred->uid))
752                 return 1;
753 
754         if (ns_capable(tcred->user_ns, CAP_KILL))
755                 return 1;
756 
757         return 0;
758 }
759 
760 /*
761  * Bad permissions for sending the signal
762  * - the caller must hold the RCU read lock
763  */
764 static int check_kill_permission(int sig, struct siginfo *info,
765                                  struct task_struct *t)
766 {
767         struct pid *sid;
768         int error;
769 
770         if (!valid_signal(sig))
771                 return -EINVAL;
772 
773         if (!si_fromuser(info))
774                 return 0;
775 
776         error = audit_signal_info(sig, t); /* Let audit system see the signal */
777         if (error)
778                 return error;
779 
780         if (!same_thread_group(current, t) &&
781             !kill_ok_by_cred(t)) {
782                 switch (sig) {
783                 case SIGCONT:
784                         sid = task_session(t);
785                         /*
786                          * We don't return the error if sid == NULL. The
787                          * task was unhashed, the caller must notice this.
788                          */
789                         if (!sid || sid == task_session(current))
790                                 break;
791                 default:
792                         return -EPERM;
793                 }
794         }
795 
796         return security_task_kill(t, info, sig, 0);
797 }
798 
799 /**
800  * ptrace_trap_notify - schedule trap to notify ptracer
801  * @t: tracee wanting to notify tracer
802  *
803  * This function schedules sticky ptrace trap which is cleared on the next
804  * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
805  * ptracer.
806  *
807  * If @t is running, STOP trap will be taken.  If trapped for STOP and
808  * ptracer is listening for events, tracee is woken up so that it can
809  * re-trap for the new event.  If trapped otherwise, STOP trap will be
810  * eventually taken without returning to userland after the existing traps
811  * are finished by PTRACE_CONT.
812  *
813  * CONTEXT:
814  * Must be called with @task->sighand->siglock held.
815  */
816 static void ptrace_trap_notify(struct task_struct *t)
817 {
818         WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
819         assert_spin_locked(&t->sighand->siglock);
820 
821         task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
822         ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
823 }
824 
825 /*
826  * Handle magic process-wide effects of stop/continue signals. Unlike
827  * the signal actions, these happen immediately at signal-generation
828  * time regardless of blocking, ignoring, or handling.  This does the
829  * actual continuing for SIGCONT, but not the actual stopping for stop
830  * signals. The process stop is done as a signal action for SIG_DFL.
831  *
832  * Returns true if the signal should be actually delivered, otherwise
833  * it should be dropped.
834  */
835 static bool prepare_signal(int sig, struct task_struct *p, bool force)
836 {
837         struct signal_struct *signal = p->signal;
838         struct task_struct *t;
839         sigset_t flush;
840 
841         if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
842                 if (signal->flags & SIGNAL_GROUP_COREDUMP)
843                         return sig == SIGKILL;
844                 /*
845                  * The process is in the middle of dying, nothing to do.
846                  */
847         } else if (sig_kernel_stop(sig)) {
848                 /*
849                  * This is a stop signal.  Remove SIGCONT from all queues.
850                  */
851                 siginitset(&flush, sigmask(SIGCONT));
852                 flush_sigqueue_mask(&flush, &signal->shared_pending);
853                 for_each_thread(p, t)
854                         flush_sigqueue_mask(&flush, &t->pending);
855         } else if (sig == SIGCONT) {
856                 unsigned int why;
857                 /*
858                  * Remove all stop signals from all queues, wake all threads.
859                  */
860                 siginitset(&flush, SIG_KERNEL_STOP_MASK);
861                 flush_sigqueue_mask(&flush, &signal->shared_pending);
862                 for_each_thread(p, t) {
863                         flush_sigqueue_mask(&flush, &t->pending);
864                         task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
865                         if (likely(!(t->ptrace & PT_SEIZED)))
866                                 wake_up_state(t, __TASK_STOPPED);
867                         else
868                                 ptrace_trap_notify(t);
869                 }
870 
871                 /*
872                  * Notify the parent with CLD_CONTINUED if we were stopped.
873                  *
874                  * If we were in the middle of a group stop, we pretend it
875                  * was already finished, and then continued. Since SIGCHLD
876                  * doesn't queue we report only CLD_STOPPED, as if the next
877                  * CLD_CONTINUED was dropped.
878                  */
879                 why = 0;
880                 if (signal->flags & SIGNAL_STOP_STOPPED)
881                         why |= SIGNAL_CLD_CONTINUED;
882                 else if (signal->group_stop_count)
883                         why |= SIGNAL_CLD_STOPPED;
884 
885                 if (why) {
886                         /*
887                          * The first thread which returns from do_signal_stop()
888                          * will take ->siglock, notice SIGNAL_CLD_MASK, and
889                          * notify its parent. See get_signal_to_deliver().
890                          */
891                         signal->flags = why | SIGNAL_STOP_CONTINUED;
892                         signal->group_stop_count = 0;
893                         signal->group_exit_code = 0;
894                 }
895         }
896 
897         return !sig_ignored(p, sig, force);
898 }
899 
900 /*
901  * Test if P wants to take SIG.  After we've checked all threads with this,
902  * it's equivalent to finding no threads not blocking SIG.  Any threads not
903  * blocking SIG were ruled out because they are not running and already
904  * have pending signals.  Such threads will dequeue from the shared queue
905  * as soon as they're available, so putting the signal on the shared queue
906  * will be equivalent to sending it to one such thread.
907  */
908 static inline int wants_signal(int sig, struct task_struct *p)
909 {
910         if (sigismember(&p->blocked, sig))
911                 return 0;
912         if (p->flags & PF_EXITING)
913                 return 0;
914         if (sig == SIGKILL)
915                 return 1;
916         if (task_is_stopped_or_traced(p))
917                 return 0;
918         return task_curr(p) || !signal_pending(p);
919 }
920 
921 static void complete_signal(int sig, struct task_struct *p, int group)
922 {
923         struct signal_struct *signal = p->signal;
924         struct task_struct *t;
925 
926         /*
927          * Now find a thread we can wake up to take the signal off the queue.
928          *
929          * If the main thread wants the signal, it gets first crack.
930          * Probably the least surprising to the average bear.
931          */
932         if (wants_signal(sig, p))
933                 t = p;
934         else if (!group || thread_group_empty(p))
935                 /*
936                  * There is just one thread and it does not need to be woken.
937                  * It will dequeue unblocked signals before it runs again.
938                  */
939                 return;
940         else {
941                 /*
942                  * Otherwise try to find a suitable thread.
943                  */
944                 t = signal->curr_target;
945                 while (!wants_signal(sig, t)) {
946                         t = next_thread(t);
947                         if (t == signal->curr_target)
948                                 /*
949                                  * No thread needs to be woken.
950                                  * Any eligible threads will see
951                                  * the signal in the queue soon.
952                                  */
953                                 return;
954                 }
955                 signal->curr_target = t;
956         }
957 
958         /*
959          * Found a killable thread.  If the signal will be fatal,
960          * then start taking the whole group down immediately.
961          */
962         if (sig_fatal(p, sig) &&
963             !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
964             !sigismember(&t->real_blocked, sig) &&
965             (sig == SIGKILL || !t->ptrace)) {
966                 /*
967                  * This signal will be fatal to the whole group.
968                  */
969                 if (!sig_kernel_coredump(sig)) {
970                         /*
971                          * Start a group exit and wake everybody up.
972                          * This way we don't have other threads
973                          * running and doing things after a slower
974                          * thread has the fatal signal pending.
975                          */
976                         signal->flags = SIGNAL_GROUP_EXIT;
977                         signal->group_exit_code = sig;
978                         signal->group_stop_count = 0;
979                         t = p;
980                         do {
981                                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
982                                 sigaddset(&t->pending.signal, SIGKILL);
983                                 signal_wake_up(t, 1);
984                         } while_each_thread(p, t);
985                         return;
986                 }
987         }
988 
989         /*
990          * The signal is already in the shared-pending queue.
991          * Tell the chosen thread to wake up and dequeue it.
992          */
993         signal_wake_up(t, sig == SIGKILL);
994         return;
995 }
996 
997 static inline int legacy_queue(struct sigpending *signals, int sig)
998 {
999         return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1000 }
1001 
1002 #ifdef CONFIG_USER_NS
1003 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1004 {
1005         if (current_user_ns() == task_cred_xxx(t, user_ns))
1006                 return;
1007 
1008         if (SI_FROMKERNEL(info))
1009                 return;
1010 
1011         rcu_read_lock();
1012         info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1013                                         make_kuid(current_user_ns(), info->si_uid));
1014         rcu_read_unlock();
1015 }
1016 #else
1017 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1018 {
1019         return;
1020 }
1021 #endif
1022 
1023 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1024                         int group, int from_ancestor_ns)
1025 {
1026         struct sigpending *pending;
1027         struct sigqueue *q;
1028         int override_rlimit;
1029         int ret = 0, result;
1030 
1031         assert_spin_locked(&t->sighand->siglock);
1032 
1033         result = TRACE_SIGNAL_IGNORED;
1034         if (!prepare_signal(sig, t,
1035                         from_ancestor_ns || (info == SEND_SIG_FORCED)))
1036                 goto ret;
1037 
1038         pending = group ? &t->signal->shared_pending : &t->pending;
1039         /*
1040          * Short-circuit ignored signals and support queuing
1041          * exactly one non-rt signal, so that we can get more
1042          * detailed information about the cause of the signal.
1043          */
1044         result = TRACE_SIGNAL_ALREADY_PENDING;
1045         if (legacy_queue(pending, sig))
1046                 goto ret;
1047 
1048         result = TRACE_SIGNAL_DELIVERED;
1049         /*
1050          * fast-pathed signals for kernel-internal things like SIGSTOP
1051          * or SIGKILL.
1052          */
1053         if (info == SEND_SIG_FORCED)
1054                 goto out_set;
1055 
1056         /*
1057          * Real-time signals must be queued if sent by sigqueue, or
1058          * some other real-time mechanism.  It is implementation
1059          * defined whether kill() does so.  We attempt to do so, on
1060          * the principle of least surprise, but since kill is not
1061          * allowed to fail with EAGAIN when low on memory we just
1062          * make sure at least one signal gets delivered and don't
1063          * pass on the info struct.
1064          */
1065         if (sig < SIGRTMIN)
1066                 override_rlimit = (is_si_special(info) || info->si_code >= 0);
1067         else
1068                 override_rlimit = 0;
1069 
1070         q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1071                 override_rlimit);
1072         if (q) {
1073                 list_add_tail(&q->list, &pending->list);
1074                 switch ((unsigned long) info) {
1075                 case (unsigned long) SEND_SIG_NOINFO:
1076                         q->info.si_signo = sig;
1077                         q->info.si_errno = 0;
1078                         q->info.si_code = SI_USER;
1079                         q->info.si_pid = task_tgid_nr_ns(current,
1080                                                         task_active_pid_ns(t));
1081                         q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1082                         break;
1083                 case (unsigned long) SEND_SIG_PRIV:
1084                         q->info.si_signo = sig;
1085                         q->info.si_errno = 0;
1086                         q->info.si_code = SI_KERNEL;
1087                         q->info.si_pid = 0;
1088                         q->info.si_uid = 0;
1089                         break;
1090                 default:
1091                         copy_siginfo(&q->info, info);
1092                         if (from_ancestor_ns)
1093                                 q->info.si_pid = 0;
1094                         break;
1095                 }
1096 
1097                 userns_fixup_signal_uid(&q->info, t);
1098 
1099         } else if (!is_si_special(info)) {
1100                 if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1101                         /*
1102                          * Queue overflow, abort.  We may abort if the
1103                          * signal was rt and sent by user using something
1104                          * other than kill().
1105                          */
1106                         result = TRACE_SIGNAL_OVERFLOW_FAIL;
1107                         ret = -EAGAIN;
1108                         goto ret;
1109                 } else {
1110                         /*
1111                          * This is a silent loss of information.  We still
1112                          * send the signal, but the *info bits are lost.
1113                          */
1114                         result = TRACE_SIGNAL_LOSE_INFO;
1115                 }
1116         }
1117 
1118 out_set:
1119         signalfd_notify(t, sig);
1120         sigaddset(&pending->signal, sig);
1121         complete_signal(sig, t, group);
1122 ret:
1123         trace_signal_generate(sig, info, t, group, result);
1124         return ret;
1125 }
1126 
1127 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1128                         int group)
1129 {
1130         int from_ancestor_ns = 0;
1131 
1132 #ifdef CONFIG_PID_NS
1133         from_ancestor_ns = si_fromuser(info) &&
1134                            !task_pid_nr_ns(current, task_active_pid_ns(t));
1135 #endif
1136 
1137         return __send_signal(sig, info, t, group, from_ancestor_ns);
1138 }
1139 
1140 static void print_fatal_signal(int signr)
1141 {
1142         struct pt_regs *regs = signal_pt_regs();
1143         printk(KERN_INFO "potentially unexpected fatal signal %d.\n", signr);
1144 
1145 #if defined(__i386__) && !defined(__arch_um__)
1146         printk(KERN_INFO "code at %08lx: ", regs->ip);
1147         {
1148                 int i;
1149                 for (i = 0; i < 16; i++) {
1150                         unsigned char insn;
1151 
1152                         if (get_user(insn, (unsigned char *)(regs->ip + i)))
1153                                 break;
1154                         printk(KERN_CONT "%02x ", insn);
1155                 }
1156         }
1157         printk(KERN_CONT "\n");
1158 #endif
1159         preempt_disable();
1160         show_regs(regs);
1161         preempt_enable();
1162 }
1163 
1164 static int __init setup_print_fatal_signals(char *str)
1165 {
1166         get_option (&str, &print_fatal_signals);
1167 
1168         return 1;
1169 }
1170 
1171 __setup("print-fatal-signals=", setup_print_fatal_signals);
1172 
1173 int
1174 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1175 {
1176         return send_signal(sig, info, p, 1);
1177 }
1178 
1179 static int
1180 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1181 {
1182         return send_signal(sig, info, t, 0);
1183 }
1184 
1185 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1186                         bool group)
1187 {
1188         unsigned long flags;
1189         int ret = -ESRCH;
1190 
1191         if (lock_task_sighand(p, &flags)) {
1192                 ret = send_signal(sig, info, p, group);
1193                 unlock_task_sighand(p, &flags);
1194         }
1195 
1196         return ret;
1197 }
1198 
1199 /*
1200  * Force a signal that the process can't ignore: if necessary
1201  * we unblock the signal and change any SIG_IGN to SIG_DFL.
1202  *
1203  * Note: If we unblock the signal, we always reset it to SIG_DFL,
1204  * since we do not want to have a signal handler that was blocked
1205  * be invoked when user space had explicitly blocked it.
1206  *
1207  * We don't want to have recursive SIGSEGV's etc, for example,
1208  * that is why we also clear SIGNAL_UNKILLABLE.
1209  */
1210 int
1211 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1212 {
1213         unsigned long int flags;
1214         int ret, blocked, ignored;
1215         struct k_sigaction *action;
1216 
1217         spin_lock_irqsave(&t->sighand->siglock, flags);
1218         action = &t->sighand->action[sig-1];
1219         ignored = action->sa.sa_handler == SIG_IGN;
1220         blocked = sigismember(&t->blocked, sig);
1221         if (blocked || ignored) {
1222                 action->sa.sa_handler = SIG_DFL;
1223                 if (blocked) {
1224                         sigdelset(&t->blocked, sig);
1225                         recalc_sigpending_and_wake(t);
1226                 }
1227         }
1228         if (action->sa.sa_handler == SIG_DFL)
1229                 t->signal->flags &= ~SIGNAL_UNKILLABLE;
1230         ret = specific_send_sig_info(sig, info, t);
1231         spin_unlock_irqrestore(&t->sighand->siglock, flags);
1232 
1233         return ret;
1234 }
1235 
1236 /*
1237  * Nuke all other threads in the group.
1238  */
1239 int zap_other_threads(struct task_struct *p)
1240 {
1241         struct task_struct *t = p;
1242         int count = 0;
1243 
1244         p->signal->group_stop_count = 0;
1245 
1246         while_each_thread(p, t) {
1247                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1248                 count++;
1249 
1250                 /* Don't bother with already dead threads */
1251                 if (t->exit_state)
1252                         continue;
1253                 sigaddset(&t->pending.signal, SIGKILL);
1254                 signal_wake_up(t, 1);
1255         }
1256 
1257         return count;
1258 }
1259 
1260 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1261                                            unsigned long *flags)
1262 {
1263         struct sighand_struct *sighand;
1264 
1265         for (;;) {
1266                 /*
1267                  * Disable interrupts early to avoid deadlocks.
1268                  * See rcu_read_unlock() comment header for details.
1269                  */
1270                 local_irq_save(*flags);
1271                 rcu_read_lock();
1272                 sighand = rcu_dereference(tsk->sighand);
1273                 if (unlikely(sighand == NULL)) {
1274                         rcu_read_unlock();
1275                         local_irq_restore(*flags);
1276                         break;
1277                 }
1278                 /*
1279                  * This sighand can be already freed and even reused, but
1280                  * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
1281                  * initializes ->siglock: this slab can't go away, it has
1282                  * the same object type, ->siglock can't be reinitialized.
1283                  *
1284                  * We need to ensure that tsk->sighand is still the same
1285                  * after we take the lock, we can race with de_thread() or
1286                  * __exit_signal(). In the latter case the next iteration
1287                  * must see ->sighand == NULL.
1288                  */
1289                 spin_lock(&sighand->siglock);
1290                 if (likely(sighand == tsk->sighand)) {
1291                         rcu_read_unlock();
1292                         break;
1293                 }
1294                 spin_unlock(&sighand->siglock);
1295                 rcu_read_unlock();
1296                 local_irq_restore(*flags);
1297         }
1298 
1299         return sighand;
1300 }
1301 
1302 /*
1303  * send signal info to all the members of a group
1304  */
1305 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1306 {
1307         int ret;
1308 
1309         rcu_read_lock();
1310         ret = check_kill_permission(sig, info, p);
1311         rcu_read_unlock();
1312 
1313         if (!ret && sig)
1314                 ret = do_send_sig_info(sig, info, p, true);
1315 
1316         return ret;
1317 }
1318 
1319 /*
1320  * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1321  * control characters do (^C, ^Z etc)
1322  * - the caller must hold at least a readlock on tasklist_lock
1323  */
1324 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1325 {
1326         struct task_struct *p = NULL;
1327         int retval, success;
1328 
1329         success = 0;
1330         retval = -ESRCH;
1331         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1332                 int err = group_send_sig_info(sig, info, p);
1333                 success |= !err;
1334                 retval = err;
1335         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1336         return success ? 0 : retval;
1337 }
1338 
1339 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1340 {
1341         int error = -ESRCH;
1342         struct task_struct *p;
1343 
1344         for (;;) {
1345                 rcu_read_lock();
1346                 p = pid_task(pid, PIDTYPE_PID);
1347                 if (p)
1348                         error = group_send_sig_info(sig, info, p);
1349                 rcu_read_unlock();
1350                 if (likely(!p || error != -ESRCH))
1351                         return error;
1352 
1353                 /*
1354                  * The task was unhashed in between, try again.  If it
1355                  * is dead, pid_task() will return NULL, if we race with
1356                  * de_thread() it will find the new leader.
1357                  */
1358         }
1359 }
1360 
1361 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1362 {
1363         int error;
1364         rcu_read_lock();
1365         error = kill_pid_info(sig, info, find_vpid(pid));
1366         rcu_read_unlock();
1367         return error;
1368 }
1369 
1370 static int kill_as_cred_perm(const struct cred *cred,
1371                              struct task_struct *target)
1372 {
1373         const struct cred *pcred = __task_cred(target);
1374         if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1375             !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
1376                 return 0;
1377         return 1;
1378 }
1379 
1380 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1381 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1382                          const struct cred *cred, u32 secid)
1383 {
1384         int ret = -EINVAL;
1385         struct task_struct *p;
1386         unsigned long flags;
1387 
1388         if (!valid_signal(sig))
1389                 return ret;
1390 
1391         rcu_read_lock();
1392         p = pid_task(pid, PIDTYPE_PID);
1393         if (!p) {
1394                 ret = -ESRCH;
1395                 goto out_unlock;
1396         }
1397         if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1398                 ret = -EPERM;
1399                 goto out_unlock;
1400         }
1401         ret = security_task_kill(p, info, sig, secid);
1402         if (ret)
1403                 goto out_unlock;
1404 
1405         if (sig) {
1406                 if (lock_task_sighand(p, &flags)) {
1407                         ret = __send_signal(sig, info, p, 1, 0);
1408                         unlock_task_sighand(p, &flags);
1409                 } else
1410                         ret = -ESRCH;
1411         }
1412 out_unlock:
1413         rcu_read_unlock();
1414         return ret;
1415 }
1416 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1417 
1418 /*
1419  * kill_something_info() interprets pid in interesting ways just like kill(2).
1420  *
1421  * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1422  * is probably wrong.  Should make it like BSD or SYSV.
1423  */
1424 
1425 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1426 {
1427         int ret;
1428 
1429         if (pid > 0) {
1430                 rcu_read_lock();
1431                 ret = kill_pid_info(sig, info, find_vpid(pid));
1432                 rcu_read_unlock();
1433                 return ret;
1434         }
1435 
1436         read_lock(&tasklist_lock);
1437         if (pid != -1) {
1438                 ret = __kill_pgrp_info(sig, info,
1439                                 pid ? find_vpid(-pid) : task_pgrp(current));
1440         } else {
1441                 int retval = 0, count = 0;
1442                 struct task_struct * p;
1443 
1444                 for_each_process(p) {
1445                         if (task_pid_vnr(p) > 1 &&
1446                                         !same_thread_group(p, current)) {
1447                                 int err = group_send_sig_info(sig, info, p);
1448                                 ++count;
1449                                 if (err != -EPERM)
1450                                         retval = err;
1451                         }
1452                 }
1453                 ret = count ? retval : -ESRCH;
1454         }
1455         read_unlock(&tasklist_lock);
1456 
1457         return ret;
1458 }
1459 
1460 /*
1461  * These are for backward compatibility with the rest of the kernel source.
1462  */
1463 
1464 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1465 {
1466         /*
1467          * Make sure legacy kernel users don't send in bad values
1468          * (normal paths check this in check_kill_permission).
1469          */
1470         if (!valid_signal(sig))
1471                 return -EINVAL;
1472 
1473         return do_send_sig_info(sig, info, p, false);
1474 }
1475 
1476 #define __si_special(priv) \
1477         ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1478 
1479 int
1480 send_sig(int sig, struct task_struct *p, int priv)
1481 {
1482         return send_sig_info(sig, __si_special(priv), p);
1483 }
1484 
1485 void
1486 force_sig(int sig, struct task_struct *p)
1487 {
1488         force_sig_info(sig, SEND_SIG_PRIV, p);
1489 }
1490 
1491 /*
1492  * When things go south during signal handling, we
1493  * will force a SIGSEGV. And if the signal that caused
1494  * the problem was already a SIGSEGV, we'll want to
1495  * make sure we don't even try to deliver the signal..
1496  */
1497 int
1498 force_sigsegv(int sig, struct task_struct *p)
1499 {
1500         if (sig == SIGSEGV) {
1501                 unsigned long flags;
1502                 spin_lock_irqsave(&p->sighand->siglock, flags);
1503                 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1504                 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1505         }
1506         force_sig(SIGSEGV, p);
1507         return 0;
1508 }
1509 
1510 int kill_pgrp(struct pid *pid, int sig, int priv)
1511 {
1512         int ret;
1513 
1514         read_lock(&tasklist_lock);
1515         ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1516         read_unlock(&tasklist_lock);
1517 
1518         return ret;
1519 }
1520 EXPORT_SYMBOL(kill_pgrp);
1521 
1522 int kill_pid(struct pid *pid, int sig, int priv)
1523 {
1524         return kill_pid_info(sig, __si_special(priv), pid);
1525 }
1526 EXPORT_SYMBOL(kill_pid);
1527 
1528 /*
1529  * These functions support sending signals using preallocated sigqueue
1530  * structures.  This is needed "because realtime applications cannot
1531  * afford to lose notifications of asynchronous events, like timer
1532  * expirations or I/O completions".  In the case of POSIX Timers
1533  * we allocate the sigqueue structure from the timer_create.  If this
1534  * allocation fails we are able to report the failure to the application
1535  * with an EAGAIN error.
1536  */
1537 struct sigqueue *sigqueue_alloc(void)
1538 {
1539         struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1540 
1541         if (q)
1542                 q->flags |= SIGQUEUE_PREALLOC;
1543 
1544         return q;
1545 }
1546 
1547 void sigqueue_free(struct sigqueue *q)
1548 {
1549         unsigned long flags;
1550         spinlock_t *lock = &current->sighand->siglock;
1551 
1552         BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1553         /*
1554          * We must hold ->siglock while testing q->list
1555          * to serialize with collect_signal() or with
1556          * __exit_signal()->flush_sigqueue().
1557          */
1558         spin_lock_irqsave(lock, flags);
1559         q->flags &= ~SIGQUEUE_PREALLOC;
1560         /*
1561          * If it is queued it will be freed when dequeued,
1562          * like the "regular" sigqueue.
1563          */
1564         if (!list_empty(&q->list))
1565                 q = NULL;
1566         spin_unlock_irqrestore(lock, flags);
1567 
1568         if (q)
1569                 __sigqueue_free(q);
1570 }
1571 
1572 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1573 {
1574         int sig = q->info.si_signo;
1575         struct sigpending *pending;
1576         unsigned long flags;
1577         int ret, result;
1578 
1579         BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1580 
1581         ret = -1;
1582         if (!likely(lock_task_sighand(t, &flags)))
1583                 goto ret;
1584 
1585         ret = 1; /* the signal is ignored */
1586         result = TRACE_SIGNAL_IGNORED;
1587         if (!prepare_signal(sig, t, false))
1588                 goto out;
1589 
1590         ret = 0;
1591         if (unlikely(!list_empty(&q->list))) {
1592                 /*
1593                  * If an SI_TIMER entry is already queue just increment
1594                  * the overrun count.
1595                  */
1596                 BUG_ON(q->info.si_code != SI_TIMER);
1597                 q->info.si_overrun++;
1598                 result = TRACE_SIGNAL_ALREADY_PENDING;
1599                 goto out;
1600         }
1601         q->info.si_overrun = 0;
1602 
1603         signalfd_notify(t, sig);
1604         pending = group ? &t->signal->shared_pending : &t->pending;
1605         list_add_tail(&q->list, &pending->list);
1606         sigaddset(&pending->signal, sig);
1607         complete_signal(sig, t, group);
1608         result = TRACE_SIGNAL_DELIVERED;
1609 out:
1610         trace_signal_generate(sig, &q->info, t, group, result);
1611         unlock_task_sighand(t, &flags);
1612 ret:
1613         return ret;
1614 }
1615 
1616 /*
1617  * Let a parent know about the death of a child.
1618  * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1619  *
1620  * Returns true if our parent ignored us and so we've switched to
1621  * self-reaping.
1622  */
1623 bool do_notify_parent(struct task_struct *tsk, int sig)
1624 {
1625         struct siginfo info;
1626         unsigned long flags;
1627         struct sighand_struct *psig;
1628         bool autoreap = false;
1629         cputime_t utime, stime;
1630 
1631         BUG_ON(sig == -1);
1632 
1633         /* do_notify_parent_cldstop should have been called instead.  */
1634         BUG_ON(task_is_stopped_or_traced(tsk));
1635 
1636         BUG_ON(!tsk->ptrace &&
1637                (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1638 
1639         if (sig != SIGCHLD) {
1640                 /*
1641                  * This is only possible if parent == real_parent.
1642                  * Check if it has changed security domain.
1643                  */
1644                 if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1645                         sig = SIGCHLD;
1646         }
1647 
1648         info.si_signo = sig;
1649         info.si_errno = 0;
1650         /*
1651          * We are under tasklist_lock here so our parent is tied to
1652          * us and cannot change.
1653          *
1654          * task_active_pid_ns will always return the same pid namespace
1655          * until a task passes through release_task.
1656          *
1657          * write_lock() currently calls preempt_disable() which is the
1658          * same as rcu_read_lock(), but according to Oleg, this is not
1659          * correct to rely on this
1660          */
1661         rcu_read_lock();
1662         info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1663         info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1664                                        task_uid(tsk));
1665         rcu_read_unlock();
1666 
1667         task_cputime(tsk, &utime, &stime);
1668         info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1669         info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1670 
1671         info.si_status = tsk->exit_code & 0x7f;
1672         if (tsk->exit_code & 0x80)
1673                 info.si_code = CLD_DUMPED;
1674         else if (tsk->exit_code & 0x7f)
1675                 info.si_code = CLD_KILLED;
1676         else {
1677                 info.si_code = CLD_EXITED;
1678                 info.si_status = tsk->exit_code >> 8;
1679         }
1680 
1681         psig = tsk->parent->sighand;
1682         spin_lock_irqsave(&psig->siglock, flags);
1683         if (!tsk->ptrace && sig == SIGCHLD &&
1684             (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1685              (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1686                 /*
1687                  * We are exiting and our parent doesn't care.  POSIX.1
1688                  * defines special semantics for setting SIGCHLD to SIG_IGN
1689                  * or setting the SA_NOCLDWAIT flag: we should be reaped
1690                  * automatically and not left for our parent's wait4 call.
1691                  * Rather than having the parent do it as a magic kind of
1692                  * signal handler, we just set this to tell do_exit that we
1693                  * can be cleaned up without becoming a zombie.  Note that
1694                  * we still call __wake_up_parent in this case, because a
1695                  * blocked sys_wait4 might now return -ECHILD.
1696                  *
1697                  * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1698                  * is implementation-defined: we do (if you don't want
1699                  * it, just use SIG_IGN instead).
1700                  */
1701                 autoreap = true;
1702                 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1703                         sig = 0;
1704         }
1705         if (valid_signal(sig) && sig)
1706                 __group_send_sig_info(sig, &info, tsk->parent);
1707         __wake_up_parent(tsk, tsk->parent);
1708         spin_unlock_irqrestore(&psig->siglock, flags);
1709 
1710         return autoreap;
1711 }
1712 
1713 /**
1714  * do_notify_parent_cldstop - notify parent of stopped/continued state change
1715  * @tsk: task reporting the state change
1716  * @for_ptracer: the notification is for ptracer
1717  * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1718  *
1719  * Notify @tsk's parent that the stopped/continued state has changed.  If
1720  * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1721  * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1722  *
1723  * CONTEXT:
1724  * Must be called with tasklist_lock at least read locked.
1725  */
1726 static void do_notify_parent_cldstop(struct task_struct *tsk,
1727                                      bool for_ptracer, int why)
1728 {
1729         struct siginfo info;
1730         unsigned long flags;
1731         struct task_struct *parent;
1732         struct sighand_struct *sighand;
1733         cputime_t utime, stime;
1734 
1735         if (for_ptracer) {
1736                 parent = tsk->parent;
1737         } else {
1738                 tsk = tsk->group_leader;
1739                 parent = tsk->real_parent;
1740         }
1741 
1742         info.si_signo = SIGCHLD;
1743         info.si_errno = 0;
1744         /*
1745          * see comment in do_notify_parent() about the following 4 lines
1746          */
1747         rcu_read_lock();
1748         info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1749         info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1750         rcu_read_unlock();
1751 
1752         task_cputime(tsk, &utime, &stime);
1753         info.si_utime = cputime_to_clock_t(utime);
1754         info.si_stime = cputime_to_clock_t(stime);
1755 
1756         info.si_code = why;
1757         switch (why) {
1758         case CLD_CONTINUED:
1759                 info.si_status = SIGCONT;
1760                 break;
1761         case CLD_STOPPED:
1762                 info.si_status = tsk->signal->group_exit_code & 0x7f;
1763                 break;
1764         case CLD_TRAPPED:
1765                 info.si_status = tsk->exit_code & 0x7f;
1766                 break;
1767         default:
1768                 BUG();
1769         }
1770 
1771         sighand = parent->sighand;
1772         spin_lock_irqsave(&sighand->siglock, flags);
1773         if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1774             !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1775                 __group_send_sig_info(SIGCHLD, &info, parent);
1776         /*
1777          * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1778          */
1779         __wake_up_parent(tsk, parent);
1780         spin_unlock_irqrestore(&sighand->siglock, flags);
1781 }
1782 
1783 static inline int may_ptrace_stop(void)
1784 {
1785         if (!likely(current->ptrace))
1786                 return 0;
1787         /*
1788          * Are we in the middle of do_coredump?
1789          * If so and our tracer is also part of the coredump stopping
1790          * is a deadlock situation, and pointless because our tracer
1791          * is dead so don't allow us to stop.
1792          * If SIGKILL was already sent before the caller unlocked
1793          * ->siglock we must see ->core_state != NULL. Otherwise it
1794          * is safe to enter schedule().
1795          *
1796          * This is almost outdated, a task with the pending SIGKILL can't
1797          * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1798          * after SIGKILL was already dequeued.
1799          */
1800         if (unlikely(current->mm->core_state) &&
1801             unlikely(current->mm == current->parent->mm))
1802                 return 0;
1803 
1804         return 1;
1805 }
1806 
1807 /*
1808  * Return non-zero if there is a SIGKILL that should be waking us up.
1809  * Called with the siglock held.
1810  */
1811 static int sigkill_pending(struct task_struct *tsk)
1812 {
1813         return  sigismember(&tsk->pending.signal, SIGKILL) ||
1814                 sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1815 }
1816 
1817 /*
1818  * This must be called with current->sighand->siglock held.
1819  *
1820  * This should be the path for all ptrace stops.
1821  * We always set current->last_siginfo while stopped here.
1822  * That makes it a way to test a stopped process for
1823  * being ptrace-stopped vs being job-control-stopped.
1824  *
1825  * If we actually decide not to stop at all because the tracer
1826  * is gone, we keep current->exit_code unless clear_code.
1827  */
1828 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1829         __releases(&current->sighand->siglock)
1830         __acquires(&current->sighand->siglock)
1831 {
1832         bool gstop_done = false;
1833 
1834         if (arch_ptrace_stop_needed(exit_code, info)) {
1835                 /*
1836                  * The arch code has something special to do before a
1837                  * ptrace stop.  This is allowed to block, e.g. for faults
1838                  * on user stack pages.  We can't keep the siglock while
1839                  * calling arch_ptrace_stop, so we must release it now.
1840                  * To preserve proper semantics, we must do this before
1841                  * any signal bookkeeping like checking group_stop_count.
1842                  * Meanwhile, a SIGKILL could come in before we retake the
1843                  * siglock.  That must prevent us from sleeping in TASK_TRACED.
1844                  * So after regaining the lock, we must check for SIGKILL.
1845                  */
1846                 spin_unlock_irq(&current->sighand->siglock);
1847                 arch_ptrace_stop(exit_code, info);
1848                 spin_lock_irq(&current->sighand->siglock);
1849                 if (sigkill_pending(current))
1850                         return;
1851         }
1852 
1853         /*
1854          * We're committing to trapping.  TRACED should be visible before
1855          * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1856          * Also, transition to TRACED and updates to ->jobctl should be
1857          * atomic with respect to siglock and should be done after the arch
1858          * hook as siglock is released and regrabbed across it.
1859          */
1860         set_current_state(TASK_TRACED);
1861 
1862         current->last_siginfo = info;
1863         current->exit_code = exit_code;
1864 
1865         /*
1866          * If @why is CLD_STOPPED, we're trapping to participate in a group
1867          * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1868          * across siglock relocks since INTERRUPT was scheduled, PENDING
1869          * could be clear now.  We act as if SIGCONT is received after
1870          * TASK_TRACED is entered - ignore it.
1871          */
1872         if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1873                 gstop_done = task_participate_group_stop(current);
1874 
1875         /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1876         task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1877         if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1878                 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1879 
1880         /* entering a trap, clear TRAPPING */
1881         task_clear_jobctl_trapping(current);
1882 
1883         spin_unlock_irq(&current->sighand->siglock);
1884         read_lock(&tasklist_lock);
1885         if (may_ptrace_stop()) {
1886                 /*
1887                  * Notify parents of the stop.
1888                  *
1889                  * While ptraced, there are two parents - the ptracer and
1890                  * the real_parent of the group_leader.  The ptracer should
1891                  * know about every stop while the real parent is only
1892                  * interested in the completion of group stop.  The states
1893                  * for the two don't interact with each other.  Notify
1894                  * separately unless they're gonna be duplicates.
1895                  */
1896                 do_notify_parent_cldstop(current, true, why);
1897                 if (gstop_done && ptrace_reparented(current))
1898                         do_notify_parent_cldstop(current, false, why);
1899 
1900                 /*
1901                  * Don't want to allow preemption here, because
1902                  * sys_ptrace() needs this task to be inactive.
1903                  *
1904                  * XXX: implement read_unlock_no_resched().
1905                  */
1906                 preempt_disable();
1907                 read_unlock(&tasklist_lock);
1908                 preempt_enable_no_resched();
1909                 freezable_schedule();
1910         } else {
1911                 /*
1912                  * By the time we got the lock, our tracer went away.
1913                  * Don't drop the lock yet, another tracer may come.
1914                  *
1915                  * If @gstop_done, the ptracer went away between group stop
1916                  * completion and here.  During detach, it would have set
1917                  * JOBCTL_STOP_PENDING on us and we'll re-enter
1918                  * TASK_STOPPED in do_signal_stop() on return, so notifying
1919                  * the real parent of the group stop completion is enough.
1920                  */
1921                 if (gstop_done)
1922                         do_notify_parent_cldstop(current, false, why);
1923 
1924                 /* tasklist protects us from ptrace_freeze_traced() */
1925                 __set_current_state(TASK_RUNNING);
1926                 if (clear_code)
1927                         current->exit_code = 0;
1928                 read_unlock(&tasklist_lock);
1929         }
1930 
1931         /*
1932          * We are back.  Now reacquire the siglock before touching
1933          * last_siginfo, so that we are sure to have synchronized with
1934          * any signal-sending on another CPU that wants to examine it.
1935          */
1936         spin_lock_irq(&current->sighand->siglock);
1937         current->last_siginfo = NULL;
1938 
1939         /* LISTENING can be set only during STOP traps, clear it */
1940         current->jobctl &= ~JOBCTL_LISTENING;
1941 
1942         /*
1943          * Queued signals ignored us while we were stopped for tracing.
1944          * So check for any that we should take before resuming user mode.
1945          * This sets TIF_SIGPENDING, but never clears it.
1946          */
1947         recalc_sigpending_tsk(current);
1948 }
1949 
1950 static void ptrace_do_notify(int signr, int exit_code, int why)
1951 {
1952         siginfo_t info;
1953 
1954         memset(&info, 0, sizeof info);
1955         info.si_signo = signr;
1956         info.si_code = exit_code;
1957         info.si_pid = task_pid_vnr(current);
1958         info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1959 
1960         /* Let the debugger run.  */
1961         ptrace_stop(exit_code, why, 1, &info);
1962 }
1963 
1964 void ptrace_notify(int exit_code)
1965 {
1966         BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1967         if (unlikely(current->task_works))
1968                 task_work_run();
1969 
1970         spin_lock_irq(&current->sighand->siglock);
1971         ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1972         spin_unlock_irq(&current->sighand->siglock);
1973 }
1974 
1975 /**
1976  * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1977  * @signr: signr causing group stop if initiating
1978  *
1979  * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1980  * and participate in it.  If already set, participate in the existing
1981  * group stop.  If participated in a group stop (and thus slept), %true is
1982  * returned with siglock released.
1983  *
1984  * If ptraced, this function doesn't handle stop itself.  Instead,
1985  * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1986  * untouched.  The caller must ensure that INTERRUPT trap handling takes
1987  * places afterwards.
1988  *
1989  * CONTEXT:
1990  * Must be called with @current->sighand->siglock held, which is released
1991  * on %true return.
1992  *
1993  * RETURNS:
1994  * %false if group stop is already cancelled or ptrace trap is scheduled.
1995  * %true if participated in group stop.
1996  */
1997 static bool do_signal_stop(int signr)
1998         __releases(&current->sighand->siglock)
1999 {
2000         struct signal_struct *sig = current->signal;
2001 
2002         if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2003                 unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2004                 struct task_struct *t;
2005 
2006                 /* signr will be recorded in task->jobctl for retries */
2007                 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2008 
2009                 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2010                     unlikely(signal_group_exit(sig)))
2011                         return false;
2012                 /*
2013                  * There is no group stop already in progress.  We must
2014                  * initiate one now.
2015                  *
2016                  * While ptraced, a task may be resumed while group stop is
2017                  * still in effect and then receive a stop signal and
2018                  * initiate another group stop.  This deviates from the
2019                  * usual behavior as two consecutive stop signals can't
2020                  * cause two group stops when !ptraced.  That is why we
2021                  * also check !task_is_stopped(t) below.
2022                  *
2023                  * The condition can be distinguished by testing whether
2024                  * SIGNAL_STOP_STOPPED is already set.  Don't generate
2025                  * group_exit_code in such case.
2026                  *
2027                  * This is not necessary for SIGNAL_STOP_CONTINUED because
2028                  * an intervening stop signal is required to cause two
2029                  * continued events regardless of ptrace.
2030                  */
2031                 if (!(sig->flags & SIGNAL_STOP_STOPPED))
2032                         sig->group_exit_code = signr;
2033 
2034                 sig->group_stop_count = 0;
2035 
2036                 if (task_set_jobctl_pending(current, signr | gstop))
2037                         sig->group_stop_count++;
2038 
2039                 t = current;
2040                 while_each_thread(current, t) {
2041                         /*
2042                          * Setting state to TASK_STOPPED for a group
2043                          * stop is always done with the siglock held,
2044                          * so this check has no races.
2045                          */
2046                         if (!task_is_stopped(t) &&
2047                             task_set_jobctl_pending(t, signr | gstop)) {
2048                                 sig->group_stop_count++;
2049                                 if (likely(!(t->ptrace & PT_SEIZED)))
2050                                         signal_wake_up(t, 0);
2051                                 else
2052                                         ptrace_trap_notify(t);
2053                         }
2054                 }
2055         }
2056 
2057         if (likely(!current->ptrace)) {
2058                 int notify = 0;
2059 
2060                 /*
2061                  * If there are no other threads in the group, or if there
2062                  * is a group stop in progress and we are the last to stop,
2063                  * report to the parent.
2064                  */
2065                 if (task_participate_group_stop(current))
2066                         notify = CLD_STOPPED;
2067 
2068                 __set_current_state(TASK_STOPPED);
2069                 spin_unlock_irq(&current->sighand->siglock);
2070 
2071                 /*
2072                  * Notify the parent of the group stop completion.  Because
2073                  * we're not holding either the siglock or tasklist_lock
2074                  * here, ptracer may attach inbetween; however, this is for
2075                  * group stop and should always be delivered to the real
2076                  * parent of the group leader.  The new ptracer will get
2077                  * its notification when this task transitions into
2078                  * TASK_TRACED.
2079                  */
2080                 if (notify) {
2081                         read_lock(&tasklist_lock);
2082                         do_notify_parent_cldstop(current, false, notify);
2083                         read_unlock(&tasklist_lock);
2084                 }
2085 
2086                 /* Now we don't run again until woken by SIGCONT or SIGKILL */
2087                 freezable_schedule();
2088                 return true;
2089         } else {
2090                 /*
2091                  * While ptraced, group stop is handled by STOP trap.
2092                  * Schedule it and let the caller deal with it.
2093                  */
2094                 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2095                 return false;
2096         }
2097 }
2098 
2099 /**
2100  * do_jobctl_trap - take care of ptrace jobctl traps
2101  *
2102  * When PT_SEIZED, it's used for both group stop and explicit
2103  * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
2104  * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
2105  * the stop signal; otherwise, %SIGTRAP.
2106  *
2107  * When !PT_SEIZED, it's used only for group stop trap with stop signal
2108  * number as exit_code and no siginfo.
2109  *
2110  * CONTEXT:
2111  * Must be called with @current->sighand->siglock held, which may be
2112  * released and re-acquired before returning with intervening sleep.
2113  */
2114 static void do_jobctl_trap(void)
2115 {
2116         struct signal_struct *signal = current->signal;
2117         int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2118 
2119         if (current->ptrace & PT_SEIZED) {
2120                 if (!signal->group_stop_count &&
2121                     !(signal->flags & SIGNAL_STOP_STOPPED))
2122                         signr = SIGTRAP;
2123                 WARN_ON_ONCE(!signr);
2124                 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2125                                  CLD_STOPPED);
2126         } else {
2127                 WARN_ON_ONCE(!signr);
2128                 ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2129                 current->exit_code = 0;
2130         }
2131 }
2132 
2133 static int ptrace_signal(int signr, siginfo_t *info)
2134 {
2135         ptrace_signal_deliver();
2136         /*
2137          * We do not check sig_kernel_stop(signr) but set this marker
2138          * unconditionally because we do not know whether debugger will
2139          * change signr. This flag has no meaning unless we are going
2140          * to stop after return from ptrace_stop(). In this case it will
2141          * be checked in do_signal_stop(), we should only stop if it was
2142          * not cleared by SIGCONT while we were sleeping. See also the
2143          * comment in dequeue_signal().
2144          */
2145         current->jobctl |= JOBCTL_STOP_DEQUEUED;
2146         ptrace_stop(signr, CLD_TRAPPED, 0, info);
2147 
2148         /* We're back.  Did the debugger cancel the sig?  */
2149         signr = current->exit_code;
2150         if (signr == 0)
2151                 return signr;
2152 
2153         current->exit_code = 0;
2154 
2155         /*
2156          * Update the siginfo structure if the signal has
2157          * changed.  If the debugger wanted something
2158          * specific in the siginfo structure then it should
2159          * have updated *info via PTRACE_SETSIGINFO.
2160          */
2161         if (signr != info->si_signo) {
2162                 info->si_signo = signr;
2163                 info->si_errno = 0;
2164                 info->si_code = SI_USER;
2165                 rcu_read_lock();
2166                 info->si_pid = task_pid_vnr(current->parent);
2167                 info->si_uid = from_kuid_munged(current_user_ns(),
2168                                                 task_uid(current->parent));
2169                 rcu_read_unlock();
2170         }
2171 
2172         /* If the (new) signal is now blocked, requeue it.  */
2173         if (sigismember(&current->blocked, signr)) {
2174                 specific_send_sig_info(signr, info, current);
2175                 signr = 0;
2176         }
2177 
2178         return signr;
2179 }
2180 
2181 int get_signal(struct ksignal *ksig)
2182 {
2183         struct sighand_struct *sighand = current->sighand;
2184         struct signal_struct *signal = current->signal;
2185         int signr;
2186 
2187         if (unlikely(current->task_works))
2188                 task_work_run();
2189 
2190         if (unlikely(uprobe_deny_signal()))
2191                 return 0;
2192 
2193         /*
2194          * Do this once, we can't return to user-mode if freezing() == T.
2195          * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2196          * thus do not need another check after return.
2197          */
2198         try_to_freeze();
2199 
2200 relock:
2201         spin_lock_irq(&sighand->siglock);
2202         /*
2203          * Every stopped thread goes here after wakeup. Check to see if
2204          * we should notify the parent, prepare_signal(SIGCONT) encodes
2205          * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2206          */
2207         if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2208                 int why;
2209 
2210                 if (signal->flags & SIGNAL_CLD_CONTINUED)
2211                         why = CLD_CONTINUED;
2212                 else
2213                         why = CLD_STOPPED;
2214 
2215                 signal->flags &= ~SIGNAL_CLD_MASK;
2216 
2217                 spin_unlock_irq(&sighand->siglock);
2218 
2219                 /*
2220                  * Notify the parent that we're continuing.  This event is
2221                  * always per-process and doesn't make whole lot of sense
2222                  * for ptracers, who shouldn't consume the state via
2223                  * wait(2) either, but, for backward compatibility, notify
2224                  * the ptracer of the group leader too unless it's gonna be
2225                  * a duplicate.
2226                  */
2227                 read_lock(&tasklist_lock);
2228                 do_notify_parent_cldstop(current, false, why);
2229 
2230                 if (ptrace_reparented(current->group_leader))
2231                         do_notify_parent_cldstop(current->group_leader,
2232                                                 true, why);
2233                 read_unlock(&tasklist_lock);
2234 
2235                 goto relock;
2236         }
2237 
2238         for (;;) {
2239                 struct k_sigaction *ka;
2240 
2241                 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2242                     do_signal_stop(0))
2243                         goto relock;
2244 
2245                 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2246                         do_jobctl_trap();
2247                         spin_unlock_irq(&sighand->siglock);
2248                         goto relock;
2249                 }
2250 
2251                 signr = dequeue_signal(current, &current->blocked, &ksig->info);
2252 
2253                 if (!signr)
2254                         break; /* will return 0 */
2255 
2256                 if (unlikely(current->ptrace) && signr != SIGKILL) {
2257                         signr = ptrace_signal(signr, &ksig->info);
2258                         if (!signr)
2259                                 continue;
2260                 }
2261 
2262                 ka = &sighand->action[signr-1];
2263 
2264                 /* Trace actually delivered signals. */
2265                 trace_signal_deliver(signr, &ksig->info, ka);
2266 
2267                 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
2268                         continue;
2269                 if (ka->sa.sa_handler != SIG_DFL) {
2270                         /* Run the handler.  */
2271                         ksig->ka = *ka;
2272 
2273                         if (ka->sa.sa_flags & SA_ONESHOT)
2274                                 ka->sa.sa_handler = SIG_DFL;
2275 
2276                         break; /* will return non-zero "signr" value */
2277                 }
2278 
2279                 /*
2280                  * Now we are doing the default action for this signal.
2281                  */
2282                 if (sig_kernel_ignore(signr)) /* Default is nothing. */
2283                         continue;
2284 
2285                 /*
2286                  * Global init gets no signals it doesn't want.
2287                  * Container-init gets no signals it doesn't want from same
2288                  * container.
2289                  *
2290                  * Note that if global/container-init sees a sig_kernel_only()
2291                  * signal here, the signal must have been generated internally
2292                  * or must have come from an ancestor namespace. In either
2293                  * case, the signal cannot be dropped.
2294                  */
2295                 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2296                                 !sig_kernel_only(signr))
2297                         continue;
2298 
2299                 if (sig_kernel_stop(signr)) {
2300                         /*
2301                          * The default action is to stop all threads in
2302                          * the thread group.  The job control signals
2303                          * do nothing in an orphaned pgrp, but SIGSTOP
2304                          * always works.  Note that siglock needs to be
2305                          * dropped during the call to is_orphaned_pgrp()
2306                          * because of lock ordering with tasklist_lock.
2307                          * This allows an intervening SIGCONT to be posted.
2308                          * We need to check for that and bail out if necessary.
2309                          */
2310                         if (signr != SIGSTOP) {
2311                                 spin_unlock_irq(&sighand->siglock);
2312 
2313                                 /* signals can be posted during this window */
2314 
2315                                 if (is_current_pgrp_orphaned())
2316                                         goto relock;
2317 
2318                                 spin_lock_irq(&sighand->siglock);
2319                         }
2320 
2321                         if (likely(do_signal_stop(ksig->info.si_signo))) {
2322                                 /* It released the siglock.  */
2323                                 goto relock;
2324                         }
2325 
2326                         /*
2327                          * We didn't actually stop, due to a race
2328                          * with SIGCONT or something like that.
2329                          */
2330                         continue;
2331                 }
2332 
2333                 spin_unlock_irq(&sighand->siglock);
2334 
2335                 /*
2336                  * Anything else is fatal, maybe with a core dump.
2337                  */
2338                 current->flags |= PF_SIGNALED;
2339 
2340                 if (sig_kernel_coredump(signr)) {
2341                         if (print_fatal_signals)
2342                                 print_fatal_signal(ksig->info.si_signo);
2343                         proc_coredump_connector(current);
2344                         /*
2345                          * If it was able to dump core, this kills all
2346                          * other threads in the group and synchronizes with
2347                          * their demise.  If we lost the race with another
2348                          * thread getting here, it set group_exit_code
2349                          * first and our do_group_exit call below will use
2350                          * that value and ignore the one we pass it.
2351                          */
2352                         do_coredump(&ksig->info);
2353                 }
2354 
2355                 /*
2356                  * Death signals, no core dump.
2357                  */
2358                 do_group_exit(ksig->info.si_signo);
2359                 /* NOTREACHED */
2360         }
2361         spin_unlock_irq(&sighand->siglock);
2362 
2363         ksig->sig = signr;
2364         return ksig->sig > 0;
2365 }
2366 
2367 /**
2368  * signal_delivered - 
2369  * @ksig:               kernel signal struct
2370  * @stepping:           nonzero if debugger single-step or block-step in use
2371  *
2372  * This function should be called when a signal has successfully been
2373  * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2374  * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2375  * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2376  */
2377 static void signal_delivered(struct ksignal *ksig, int stepping)
2378 {
2379         sigset_t blocked;
2380 
2381         /* A signal was successfully delivered, and the
2382            saved sigmask was stored on the signal frame,
2383            and will be restored by sigreturn.  So we can
2384            simply clear the restore sigmask flag.  */
2385         clear_restore_sigmask();
2386 
2387         sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
2388         if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2389                 sigaddset(&blocked, ksig->sig);
2390         set_current_blocked(&blocked);
2391         tracehook_signal_handler(stepping);
2392 }
2393 
2394 void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2395 {
2396         if (failed)
2397                 force_sigsegv(ksig->sig, current);
2398         else
2399                 signal_delivered(ksig, stepping);
2400 }
2401 
2402 /*
2403  * It could be that complete_signal() picked us to notify about the
2404  * group-wide signal. Other threads should be notified now to take
2405  * the shared signals in @which since we will not.
2406  */
2407 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2408 {
2409         sigset_t retarget;
2410         struct task_struct *t;
2411 
2412         sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2413         if (sigisemptyset(&retarget))
2414                 return;
2415 
2416         t = tsk;
2417         while_each_thread(tsk, t) {
2418                 if (t->flags & PF_EXITING)
2419                         continue;
2420 
2421                 if (!has_pending_signals(&retarget, &t->blocked))
2422                         continue;
2423                 /* Remove the signals this thread can handle. */
2424                 sigandsets(&retarget, &retarget, &t->blocked);
2425 
2426                 if (!signal_pending(t))
2427                         signal_wake_up(t, 0);
2428 
2429                 if (sigisemptyset(&retarget))
2430                         break;
2431         }
2432 }
2433 
2434 void exit_signals(struct task_struct *tsk)
2435 {
2436         int group_stop = 0;
2437         sigset_t unblocked;
2438 
2439         /*
2440          * @tsk is about to have PF_EXITING set - lock out users which
2441          * expect stable threadgroup.
2442          */
2443         threadgroup_change_begin(tsk);
2444 
2445         if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2446                 tsk->flags |= PF_EXITING;
2447                 threadgroup_change_end(tsk);
2448                 return;
2449         }
2450 
2451         spin_lock_irq(&tsk->sighand->siglock);
2452         /*
2453          * From now this task is not visible for group-wide signals,
2454          * see wants_signal(), do_signal_stop().
2455          */
2456         tsk->flags |= PF_EXITING;
2457 
2458         threadgroup_change_end(tsk);
2459 
2460         if (!signal_pending(tsk))
2461                 goto out;
2462 
2463         unblocked = tsk->blocked;
2464         signotset(&unblocked);
2465         retarget_shared_pending(tsk, &unblocked);
2466 
2467         if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2468             task_participate_group_stop(tsk))
2469                 group_stop = CLD_STOPPED;
2470 out:
2471         spin_unlock_irq(&tsk->sighand->siglock);
2472 
2473         /*
2474          * If group stop has completed, deliver the notification.  This
2475          * should always go to the real parent of the group leader.
2476          */
2477         if (unlikely(group_stop)) {
2478                 read_lock(&tasklist_lock);
2479                 do_notify_parent_cldstop(tsk, false, group_stop);
2480                 read_unlock(&tasklist_lock);
2481         }
2482 }
2483 
2484 EXPORT_SYMBOL(recalc_sigpending);
2485 EXPORT_SYMBOL_GPL(dequeue_signal);
2486 EXPORT_SYMBOL(flush_signals);
2487 EXPORT_SYMBOL(force_sig);
2488 EXPORT_SYMBOL(send_sig);
2489 EXPORT_SYMBOL(send_sig_info);
2490 EXPORT_SYMBOL(sigprocmask);
2491 EXPORT_SYMBOL(block_all_signals);
2492 EXPORT_SYMBOL(unblock_all_signals);
2493 
2494 
2495 /*
2496  * System call entry points.
2497  */
2498 
2499 /**
2500  *  sys_restart_syscall - restart a system call
2501  */
2502 SYSCALL_DEFINE0(restart_syscall)
2503 {
2504         struct restart_block *restart = &current->restart_block;
2505         return restart->fn(restart);
2506 }
2507 
2508 long do_no_restart_syscall(struct restart_block *param)
2509 {
2510         return -EINTR;
2511 }
2512 
2513 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2514 {
2515         if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2516                 sigset_t newblocked;
2517                 /* A set of now blocked but previously unblocked signals. */
2518                 sigandnsets(&newblocked, newset, &current->blocked);
2519                 retarget_shared_pending(tsk, &newblocked);
2520         }
2521         tsk->blocked = *newset;
2522         recalc_sigpending();
2523 }
2524 
2525 /**
2526  * set_current_blocked - change current->blocked mask
2527  * @newset: new mask
2528  *
2529  * It is wrong to change ->blocked directly, this helper should be used
2530  * to ensure the process can't miss a shared signal we are going to block.
2531  */
2532 void set_current_blocked(sigset_t *newset)
2533 {
2534         sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2535         __set_current_blocked(newset);
2536 }
2537 
2538 void __set_current_blocked(const sigset_t *newset)
2539 {
2540         struct task_struct *tsk = current;
2541 
2542         spin_lock_irq(&tsk->sighand->siglock);
2543         __set_task_blocked(tsk, newset);
2544         spin_unlock_irq(&tsk->sighand->siglock);
2545 }
2546 
2547 /*
2548  * This is also useful for kernel threads that want to temporarily
2549  * (or permanently) block certain signals.
2550  *
2551  * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2552  * interface happily blocks "unblockable" signals like SIGKILL
2553  * and friends.
2554  */
2555 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2556 {
2557         struct task_struct *tsk = current;
2558         sigset_t newset;
2559 
2560         /* Lockless, only current can change ->blocked, never from irq */
2561         if (oldset)
2562                 *oldset = tsk->blocked;
2563 
2564         switch (how) {
2565         case SIG_BLOCK:
2566                 sigorsets(&newset, &tsk->blocked, set);
2567                 break;
2568         case SIG_UNBLOCK:
2569                 sigandnsets(&newset, &tsk->blocked, set);
2570                 break;
2571         case SIG_SETMASK:
2572                 newset = *set;
2573                 break;
2574         default:
2575                 return -EINVAL;
2576         }
2577 
2578         __set_current_blocked(&newset);
2579         return 0;
2580 }
2581 
2582 /**
2583  *  sys_rt_sigprocmask - change the list of currently blocked signals
2584  *  @how: whether to add, remove, or set signals
2585  *  @nset: stores pending signals
2586  *  @oset: previous value of signal mask if non-null
2587  *  @sigsetsize: size of sigset_t type
2588  */
2589 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2590                 sigset_t __user *, oset, size_t, sigsetsize)
2591 {
2592         sigset_t old_set, new_set;
2593         int error;
2594 
2595         /* XXX: Don't preclude handling different sized sigset_t's.  */
2596         if (sigsetsize != sizeof(sigset_t))
2597                 return -EINVAL;
2598 
2599         old_set = current->blocked;
2600 
2601         if (nset) {
2602                 if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2603                         return -EFAULT;
2604                 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2605 
2606                 error = sigprocmask(how, &new_set, NULL);
2607                 if (error)
2608                         return error;
2609         }
2610 
2611         if (oset) {
2612                 if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2613                         return -EFAULT;
2614         }
2615 
2616         return 0;
2617 }
2618 
2619 #ifdef CONFIG_COMPAT
2620 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2621                 compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2622 {
2623 #ifdef __BIG_ENDIAN
2624         sigset_t old_set = current->blocked;
2625 
2626         /* XXX: Don't preclude handling different sized sigset_t's.  */
2627         if (sigsetsize != sizeof(sigset_t))
2628                 return -EINVAL;
2629 
2630         if (nset) {
2631                 compat_sigset_t new32;
2632                 sigset_t new_set;
2633                 int error;
2634                 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2635                         return -EFAULT;
2636 
2637                 sigset_from_compat(&new_set, &new32);
2638                 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2639 
2640                 error = sigprocmask(how, &new_set, NULL);
2641                 if (error)
2642                         return error;
2643         }
2644         if (oset) {
2645                 compat_sigset_t old32;
2646                 sigset_to_compat(&old32, &old_set);
2647                 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2648                         return -EFAULT;
2649         }
2650         return 0;
2651 #else
2652         return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2653                                   (sigset_t __user *)oset, sigsetsize);
2654 #endif
2655 }
2656 #endif
2657 
2658 static int do_sigpending(void *set, unsigned long sigsetsize)
2659 {
2660         if (sigsetsize > sizeof(sigset_t))
2661                 return -EINVAL;
2662 
2663         spin_lock_irq(&current->sighand->siglock);
2664         sigorsets(set, &current->pending.signal,
2665                   &current->signal->shared_pending.signal);
2666         spin_unlock_irq(&current->sighand->siglock);
2667 
2668         /* Outside the lock because only this thread touches it.  */
2669         sigandsets(set, &current->blocked, set);
2670         return 0;
2671 }
2672 
2673 /**
2674  *  sys_rt_sigpending - examine a pending signal that has been raised
2675  *                      while blocked
2676  *  @uset: stores pending signals
2677  *  @sigsetsize: size of sigset_t type or larger
2678  */
2679 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2680 {
2681         sigset_t set;
2682         int err = do_sigpending(&set, sigsetsize);
2683         if (!err && copy_to_user(uset, &set, sigsetsize))
2684                 err = -EFAULT;
2685         return err;
2686 }
2687 
2688 #ifdef CONFIG_COMPAT
2689 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2690                 compat_size_t, sigsetsize)
2691 {
2692 #ifdef __BIG_ENDIAN
2693         sigset_t set;
2694         int err = do_sigpending(&set, sigsetsize);
2695         if (!err) {
2696                 compat_sigset_t set32;
2697                 sigset_to_compat(&set32, &set);
2698                 /* we can get here only if sigsetsize <= sizeof(set) */
2699                 if (copy_to_user(uset, &set32, sigsetsize))
2700                         err = -EFAULT;
2701         }
2702         return err;
2703 #else
2704         return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2705 #endif
2706 }
2707 #endif
2708 
2709 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2710 
2711 int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2712 {
2713         int err;
2714 
2715         if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2716                 return -EFAULT;
2717         if (from->si_code < 0)
2718                 return __copy_to_user(to, from, sizeof(siginfo_t))
2719                         ? -EFAULT : 0;
2720         /*
2721          * If you change siginfo_t structure, please be sure
2722          * this code is fixed accordingly.
2723          * Please remember to update the signalfd_copyinfo() function
2724          * inside fs/signalfd.c too, in case siginfo_t changes.
2725          * It should never copy any pad contained in the structure
2726          * to avoid security leaks, but must copy the generic
2727          * 3 ints plus the relevant union member.
2728          */
2729         err = __put_user(from->si_signo, &to->si_signo);
2730         err |= __put_user(from->si_errno, &to->si_errno);
2731         err |= __put_user((short)from->si_code, &to->si_code);
2732         switch (from->si_code & __SI_MASK) {
2733         case __SI_KILL:
2734                 err |= __put_user(from->si_pid, &to->si_pid);
2735                 err |= __put_user(from->si_uid, &to->si_uid);
2736                 break;
2737         case __SI_TIMER:
2738                  err |= __put_user(from->si_tid, &to->si_tid);
2739                  err |= __put_user(from->si_overrun, &to->si_overrun);
2740                  err |= __put_user(from->si_ptr, &to->si_ptr);
2741                 break;
2742         case __SI_POLL:
2743                 err |= __put_user(from->si_band, &to->si_band);
2744                 err |= __put_user(from->si_fd, &to->si_fd);
2745                 break;
2746         case __SI_FAULT:
2747                 err |= __put_user(from->si_addr, &to->si_addr);
2748 #ifdef __ARCH_SI_TRAPNO
2749                 err |= __put_user(from->si_trapno, &to->si_trapno);
2750 #endif
2751 #ifdef BUS_MCEERR_AO
2752                 /*
2753                  * Other callers might not initialize the si_lsb field,
2754                  * so check explicitly for the right codes here.
2755                  */
2756                 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2757                         err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2758 #endif
2759 #ifdef SEGV_BNDERR
2760                 err |= __put_user(from->si_lower, &to->si_lower);
2761                 err |= __put_user(from->si_upper, &to->si_upper);
2762 #endif
2763                 break;
2764         case __SI_CHLD:
2765                 err |= __put_user(from->si_pid, &to->si_pid);
2766                 err |= __put_user(from->si_uid, &to->si_uid);
2767                 err |= __put_user(from->si_status, &to->si_status);
2768                 err |= __put_user(from->si_utime, &to->si_utime);
2769                 err |= __put_user(from->si_stime, &to->si_stime);
2770                 break;
2771         case __SI_RT: /* This is not generated by the kernel as of now. */
2772         case __SI_MESGQ: /* But this is */
2773                 err |= __put_user(from->si_pid, &to->si_pid);
2774                 err |= __put_user(from->si_uid, &to->si_uid);
2775                 err |= __put_user(from->si_ptr, &to->si_ptr);
2776                 break;
2777 #ifdef __ARCH_SIGSYS
2778         case __SI_SYS:
2779                 err |= __put_user(from->si_call_addr, &to->si_call_addr);
2780                 err |= __put_user(from->si_syscall, &to->si_syscall);
2781                 err |= __put_user(from->si_arch, &to->si_arch);
2782                 break;
2783 #endif
2784         default: /* this is just in case for now ... */
2785                 err |= __put_user(from->si_pid, &to->si_pid);
2786                 err |= __put_user(from->si_uid, &to->si_uid);
2787                 break;
2788         }
2789         return err;
2790 }
2791 
2792 #endif
2793 
2794 /**
2795  *  do_sigtimedwait - wait for queued signals specified in @which
2796  *  @which: queued signals to wait for
2797  *  @info: if non-null, the signal's siginfo is returned here
2798  *  @ts: upper bound on process time suspension
2799  */
2800 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2801                         const struct timespec *ts)
2802 {
2803         struct task_struct *tsk = current;
2804         long timeout = MAX_SCHEDULE_TIMEOUT;
2805         sigset_t mask = *which;
2806         int sig;
2807 
2808         if (ts) {
2809                 if (!timespec_valid(ts))
2810                         return -EINVAL;
2811                 timeout = timespec_to_jiffies(ts);
2812                 /*
2813                  * We can be close to the next tick, add another one
2814                  * to ensure we will wait at least the time asked for.
2815                  */
2816                 if (ts->tv_sec || ts->tv_nsec)
2817                         timeout++;
2818         }
2819 
2820         /*
2821          * Invert the set of allowed signals to get those we want to block.
2822          */
2823         sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2824         signotset(&mask);
2825 
2826         spin_lock_irq(&tsk->sighand->siglock);
2827         sig = dequeue_signal(tsk, &mask, info);
2828         if (!sig && timeout) {
2829                 /*
2830                  * None ready, temporarily unblock those we're interested
2831                  * while we are sleeping in so that we'll be awakened when
2832                  * they arrive. Unblocking is always fine, we can avoid
2833                  * set_current_blocked().
2834                  */
2835                 tsk->real_blocked = tsk->blocked;
2836                 sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2837                 recalc_sigpending();
2838                 spin_unlock_irq(&tsk->sighand->siglock);
2839 
2840                 timeout = freezable_schedule_timeout_interruptible(timeout);
2841 
2842                 spin_lock_irq(&tsk->sighand->siglock);
2843                 __set_task_blocked(tsk, &tsk->real_blocked);
2844                 sigemptyset(&tsk->real_blocked);
2845                 sig = dequeue_signal(tsk, &mask, info);
2846         }
2847         spin_unlock_irq(&tsk->sighand->siglock);
2848 
2849         if (sig)
2850                 return sig;
2851         return timeout ? -EINTR : -EAGAIN;
2852 }
2853 
2854 /**
2855  *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
2856  *                      in @uthese
2857  *  @uthese: queued signals to wait for
2858  *  @uinfo: if non-null, the signal's siginfo is returned here
2859  *  @uts: upper bound on process time suspension
2860  *  @sigsetsize: size of sigset_t type
2861  */
2862 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2863                 siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2864                 size_t, sigsetsize)
2865 {
2866         sigset_t these;
2867         struct timespec ts;
2868         siginfo_t info;
2869         int ret;
2870 
2871         /* XXX: Don't preclude handling different sized sigset_t's.  */
2872         if (sigsetsize != sizeof(sigset_t))
2873                 return -EINVAL;
2874 
2875         if (copy_from_user(&these, uthese, sizeof(these)))
2876                 return -EFAULT;
2877 
2878         if (uts) {
2879                 if (copy_from_user(&ts, uts, sizeof(ts)))
2880                         return -EFAULT;
2881         }
2882 
2883         ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2884 
2885         if (ret > 0 && uinfo) {
2886                 if (copy_siginfo_to_user(uinfo, &info))
2887                         ret = -EFAULT;
2888         }
2889 
2890         return ret;
2891 }
2892 
2893 /**
2894  *  sys_kill - send a signal to a process
2895  *  @pid: the PID of the process
2896  *  @sig: signal to be sent
2897  */
2898 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2899 {
2900         struct siginfo info;
2901         if (ccs_kill_permission(pid, sig))
2902                 return -EPERM;
2903 
2904         info.si_signo = sig;
2905         info.si_errno = 0;
2906         info.si_code = SI_USER;
2907         info.si_pid = task_tgid_vnr(current);
2908         info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2909 
2910         return kill_something_info(sig, &info, pid);
2911 }
2912 
2913 static int
2914 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2915 {
2916         struct task_struct *p;
2917         int error = -ESRCH;
2918 
2919         rcu_read_lock();
2920         p = find_task_by_vpid(pid);
2921         if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2922                 error = check_kill_permission(sig, info, p);
2923                 /*
2924                  * The null signal is a permissions and process existence
2925                  * probe.  No signal is actually delivered.
2926                  */
2927                 if (!error && sig) {
2928                         error = do_send_sig_info(sig, info, p, false);
2929                         /*
2930                          * If lock_task_sighand() failed we pretend the task
2931                          * dies after receiving the signal. The window is tiny,
2932                          * and the signal is private anyway.
2933                          */
2934                         if (unlikely(error == -ESRCH))
2935                                 error = 0;
2936                 }
2937         }
2938         rcu_read_unlock();
2939 
2940         return error;
2941 }
2942 
2943 static int do_tkill(pid_t tgid, pid_t pid, int sig)
2944 {
2945         struct siginfo info = {};
2946 
2947         info.si_signo = sig;
2948         info.si_errno = 0;
2949         info.si_code = SI_TKILL;
2950         info.si_pid = task_tgid_vnr(current);
2951         info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2952 
2953         return do_send_specific(tgid, pid, sig, &info);
2954 }
2955 
2956 /**
2957  *  sys_tgkill - send signal to one specific thread
2958  *  @tgid: the thread group ID of the thread
2959  *  @pid: the PID of the thread
2960  *  @sig: signal to be sent
2961  *
2962  *  This syscall also checks the @tgid and returns -ESRCH even if the PID
2963  *  exists but it's not belonging to the target process anymore. This
2964  *  method solves the problem of threads exiting and PIDs getting reused.
2965  */
2966 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2967 {
2968         /* This is only valid for single tasks */
2969         if (pid <= 0 || tgid <= 0)
2970                 return -EINVAL;
2971         if (ccs_tgkill_permission(tgid, pid, sig))
2972                 return -EPERM;
2973 
2974         return do_tkill(tgid, pid, sig);
2975 }
2976 
2977 /**
2978  *  sys_tkill - send signal to one specific task
2979  *  @pid: the PID of the task
2980  *  @sig: signal to be sent
2981  *
2982  *  Send a signal to only one task, even if it's a CLONE_THREAD task.
2983  */
2984 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2985 {
2986         /* This is only valid for single tasks */
2987         if (pid <= 0)
2988                 return -EINVAL;
2989         if (ccs_tkill_permission(pid, sig))
2990                 return -EPERM;
2991 
2992         return do_tkill(0, pid, sig);
2993 }
2994 
2995 static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2996 {
2997         /* Not even root can pretend to send signals from the kernel.
2998          * Nor can they impersonate a kill()/tgkill(), which adds source info.
2999          */
3000         if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3001             (task_pid_vnr(current) != pid)) {
3002                 /* We used to allow any < 0 si_code */
3003                 WARN_ON_ONCE(info->si_code < 0);
3004                 return -EPERM;
3005         }
3006         info->si_signo = sig;
3007         if (ccs_sigqueue_permission(pid, sig))
3008                 return -EPERM;
3009 
3010         /* POSIX.1b doesn't mention process groups.  */
3011         return kill_proc_info(sig, info, pid);
3012 }
3013 
3014 /**
3015  *  sys_rt_sigqueueinfo - send signal information to a signal
3016  *  @pid: the PID of the thread
3017  *  @sig: signal to be sent
3018  *  @uinfo: signal info to be sent
3019  */
3020 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3021                 siginfo_t __user *, uinfo)
3022 {
3023         siginfo_t info;
3024         if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3025                 return -EFAULT;
3026         return do_rt_sigqueueinfo(pid, sig, &info);
3027 }
3028 
3029 #ifdef CONFIG_COMPAT
3030 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3031                         compat_pid_t, pid,
3032                         int, sig,
3033                         struct compat_siginfo __user *, uinfo)
3034 {
3035         siginfo_t info;
3036         int ret = copy_siginfo_from_user32(&info, uinfo);
3037         if (unlikely(ret))
3038                 return ret;
3039         return do_rt_sigqueueinfo(pid, sig, &info);
3040 }
3041 #endif
3042 
3043 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3044 {
3045         /* This is only valid for single tasks */
3046         if (pid <= 0 || tgid <= 0)
3047                 return -EINVAL;
3048 
3049         /* Not even root can pretend to send signals from the kernel.
3050          * Nor can they impersonate a kill()/tgkill(), which adds source info.
3051          */
3052         if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
3053             (task_pid_vnr(current) != pid)) {
3054                 /* We used to allow any < 0 si_code */
3055                 WARN_ON_ONCE(info->si_code < 0);
3056                 return -EPERM;
3057         }
3058         info->si_signo = sig;
3059         if (ccs_tgsigqueue_permission(tgid, pid, sig))
3060                 return -EPERM;
3061 
3062         return do_send_specific(tgid, pid, sig, info);
3063 }
3064 
3065 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3066                 siginfo_t __user *, uinfo)
3067 {
3068         siginfo_t info;
3069 
3070         if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3071                 return -EFAULT;
3072 
3073         return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3074 }
3075 
3076 #ifdef CONFIG_COMPAT
3077 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3078                         compat_pid_t, tgid,
3079                         compat_pid_t, pid,
3080                         int, sig,
3081                         struct compat_siginfo __user *, uinfo)
3082 {
3083         siginfo_t info;
3084 
3085         if (copy_siginfo_from_user32(&info, uinfo))
3086                 return -EFAULT;
3087         return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3088 }
3089 #endif
3090 
3091 /*
3092  * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3093  */
3094 void kernel_sigaction(int sig, __sighandler_t action)
3095 {
3096         spin_lock_irq(&current->sighand->siglock);
3097         current->sighand->action[sig - 1].sa.sa_handler = action;
3098         if (action == SIG_IGN) {
3099                 sigset_t mask;
3100 
3101                 sigemptyset(&mask);
3102                 sigaddset(&mask, sig);
3103 
3104                 flush_sigqueue_mask(&mask, &current->signal->shared_pending);
3105                 flush_sigqueue_mask(&mask, &current->pending);
3106                 recalc_sigpending();
3107         }
3108         spin_unlock_irq(&current->sighand->siglock);
3109 }
3110 EXPORT_SYMBOL(kernel_sigaction);
3111 
3112 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3113 {
3114         struct task_struct *p = current, *t;
3115         struct k_sigaction *k;
3116         sigset_t mask;
3117 
3118         if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3119                 return -EINVAL;
3120 
3121         k = &p->sighand->action[sig-1];
3122 
3123         spin_lock_irq(&p->sighand->siglock);
3124         if (oact)
3125                 *oact = *k;
3126 
3127         if (act) {
3128                 sigdelsetmask(&act->sa.sa_mask,
3129                               sigmask(SIGKILL) | sigmask(SIGSTOP));
3130                 *k = *act;
3131                 /*
3132                  * POSIX 3.3.1.3:
3133                  *  "Setting a signal action to SIG_IGN for a signal that is
3134                  *   pending shall cause the pending signal to be discarded,
3135                  *   whether or not it is blocked."
3136                  *
3137                  *  "Setting a signal action to SIG_DFL for a signal that is
3138                  *   pending and whose default action is to ignore the signal
3139                  *   (for example, SIGCHLD), shall cause the pending signal to
3140                  *   be discarded, whether or not it is blocked"
3141                  */
3142                 if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3143                         sigemptyset(&mask);
3144                         sigaddset(&mask, sig);
3145                         flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3146                         for_each_thread(p, t)
3147                                 flush_sigqueue_mask(&mask, &t->pending);
3148                 }
3149         }
3150 
3151         spin_unlock_irq(&p->sighand->siglock);
3152         return 0;
3153 }
3154 
3155 static int
3156 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3157 {
3158         stack_t oss;
3159         int error;
3160 
3161         oss.ss_sp = (void __user *) current->sas_ss_sp;
3162         oss.ss_size = current->sas_ss_size;
3163         oss.ss_flags = sas_ss_flags(sp);
3164 
3165         if (uss) {
3166                 void __user *ss_sp;
3167                 size_t ss_size;
3168                 int ss_flags;
3169 
3170                 error = -EFAULT;
3171                 if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3172                         goto out;
3173                 error = __get_user(ss_sp, &uss->ss_sp) |
3174                         __get_user(ss_flags, &uss->ss_flags) |
3175                         __get_user(ss_size, &uss->ss_size);
3176                 if (error)
3177                         goto out;
3178 
3179                 error = -EPERM;
3180                 if (on_sig_stack(sp))
3181                         goto out;
3182 
3183                 error = -EINVAL;
3184                 /*
3185                  * Note - this code used to test ss_flags incorrectly:
3186                  *        old code may have been written using ss_flags==0
3187                  *        to mean ss_flags==SS_ONSTACK (as this was the only
3188                  *        way that worked) - this fix preserves that older
3189                  *        mechanism.
3190                  */
3191                 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3192                         goto out;
3193 
3194                 if (ss_flags == SS_DISABLE) {
3195                         ss_size = 0;
3196                         ss_sp = NULL;
3197                 } else {
3198                         error = -ENOMEM;
3199                         if (ss_size < MINSIGSTKSZ)
3200                                 goto out;
3201                 }
3202 
3203                 current->sas_ss_sp = (unsigned long) ss_sp;
3204                 current->sas_ss_size = ss_size;
3205         }
3206 
3207         error = 0;
3208         if (uoss) {
3209                 error = -EFAULT;
3210                 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3211                         goto out;
3212                 error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3213                         __put_user(oss.ss_size, &uoss->ss_size) |
3214                         __put_user(oss.ss_flags, &uoss->ss_flags);
3215         }
3216 
3217 out:
3218         return error;
3219 }
3220 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3221 {
3222         return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3223 }
3224 
3225 int restore_altstack(const stack_t __user *uss)
3226 {
3227         int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3228         /* squash all but EFAULT for now */
3229         return err == -EFAULT ? err : 0;
3230 }
3231 
3232 int __save_altstack(stack_t __user *uss, unsigned long sp)
3233 {
3234         struct task_struct *t = current;
3235         return  __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3236                 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3237                 __put_user(t->sas_ss_size, &uss->ss_size);
3238 }
3239 
3240 #ifdef CONFIG_COMPAT
3241 COMPAT_SYSCALL_DEFINE2(sigaltstack,
3242                         const compat_stack_t __user *, uss_ptr,
3243                         compat_stack_t __user *, uoss_ptr)
3244 {
3245         stack_t uss, uoss;
3246         int ret;
3247         mm_segment_t seg;
3248 
3249         if (uss_ptr) {
3250                 compat_stack_t uss32;
3251 
3252                 memset(&uss, 0, sizeof(stack_t));
3253                 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3254                         return -EFAULT;
3255                 uss.ss_sp = compat_ptr(uss32.ss_sp);
3256                 uss.ss_flags = uss32.ss_flags;
3257                 uss.ss_size = uss32.ss_size;
3258         }
3259         seg = get_fs();
3260         set_fs(KERNEL_DS);
3261         ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3262                              (stack_t __force __user *) &uoss,
3263                              compat_user_stack_pointer());
3264         set_fs(seg);
3265         if (ret >= 0 && uoss_ptr)  {
3266                 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3267                     __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3268                     __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3269                     __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3270                         ret = -EFAULT;
3271         }
3272         return ret;
3273 }
3274 
3275 int compat_restore_altstack(const compat_stack_t __user *uss)
3276 {
3277         int err = compat_sys_sigaltstack(uss, NULL);
3278         /* squash all but -EFAULT for now */
3279         return err == -EFAULT ? err : 0;
3280 }
3281 
3282 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3283 {
3284         struct task_struct *t = current;
3285         return  __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3286                 __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3287                 __put_user(t->sas_ss_size, &uss->ss_size);
3288 }
3289 #endif
3290 
3291 #ifdef __ARCH_WANT_SYS_SIGPENDING
3292 
3293 /**
3294  *  sys_sigpending - examine pending signals
3295  *  @set: where mask of pending signal is returned
3296  */
3297 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3298 {
3299         return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 
3300 }
3301 
3302 #endif
3303 
3304 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
3305 /**
3306  *  sys_sigprocmask - examine and change blocked signals
3307  *  @how: whether to add, remove, or set signals
3308  *  @nset: signals to add or remove (if non-null)
3309  *  @oset: previous value of signal mask if non-null
3310  *
3311  * Some platforms have their own version with special arguments;
3312  * others support only sys_rt_sigprocmask.
3313  */
3314 
3315 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3316                 old_sigset_t __user *, oset)
3317 {
3318         old_sigset_t old_set, new_set;
3319         sigset_t new_blocked;
3320 
3321         old_set = current->blocked.sig[0];
3322 
3323         if (nset) {
3324                 if (copy_from_user(&new_set, nset, sizeof(*nset)))
3325                         return -EFAULT;
3326 
3327                 new_blocked = current->blocked;
3328 
3329                 switch (how) {
3330                 case SIG_BLOCK:
3331                         sigaddsetmask(&new_blocked, new_set);
3332                         break;
3333                 case SIG_UNBLOCK:
3334                         sigdelsetmask(&new_blocked, new_set);
3335                         break;
3336                 case SIG_SETMASK:
3337                         new_blocked.sig[0] = new_set;
3338                         break;
3339                 default:
3340                         return -EINVAL;
3341                 }
3342 
3343                 set_current_blocked(&new_blocked);
3344         }
3345 
3346         if (oset) {
3347                 if (copy_to_user(oset, &old_set, sizeof(*oset)))
3348                         return -EFAULT;
3349         }
3350 
3351         return 0;
3352 }
3353 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3354 
3355 #ifndef CONFIG_ODD_RT_SIGACTION
3356 /**
3357  *  sys_rt_sigaction - alter an action taken by a process
3358  *  @sig: signal to be sent
3359  *  @act: new sigaction
3360  *  @oact: used to save the previous sigaction
3361  *  @sigsetsize: size of sigset_t type
3362  */
3363 SYSCALL_DEFINE4(rt_sigaction, int, sig,
3364                 const struct sigaction __user *, act,
3365                 struct sigaction __user *, oact,
3366                 size_t, sigsetsize)
3367 {
3368         struct k_sigaction new_sa, old_sa;
3369         int ret = -EINVAL;
3370 
3371         /* XXX: Don't preclude handling different sized sigset_t's.  */
3372         if (sigsetsize != sizeof(sigset_t))
3373                 goto out;
3374 
3375         if (act) {
3376                 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3377                         return -EFAULT;
3378         }
3379 
3380         ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3381 
3382         if (!ret && oact) {
3383                 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3384                         return -EFAULT;
3385         }
3386 out:
3387         return ret;
3388 }
3389 #ifdef CONFIG_COMPAT
3390 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3391                 const struct compat_sigaction __user *, act,
3392                 struct compat_sigaction __user *, oact,
3393                 compat_size_t, sigsetsize)
3394 {
3395         struct k_sigaction new_ka, old_ka;
3396         compat_sigset_t mask;
3397 #ifdef __ARCH_HAS_SA_RESTORER
3398         compat_uptr_t restorer;
3399 #endif
3400         int ret;
3401 
3402         /* XXX: Don't preclude handling different sized sigset_t's.  */
3403         if (sigsetsize != sizeof(compat_sigset_t))
3404                 return -EINVAL;
3405 
3406         if (act) {
3407                 compat_uptr_t handler;
3408                 ret = get_user(handler, &act->sa_handler);
3409                 new_ka.sa.sa_handler = compat_ptr(handler);
3410 #ifdef __ARCH_HAS_SA_RESTORER
3411                 ret |= get_user(restorer, &act->sa_restorer);
3412                 new_ka.sa.sa_restorer = compat_ptr(restorer);
3413 #endif
3414                 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3415                 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3416                 if (ret)
3417                         return -EFAULT;
3418                 sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3419         }
3420 
3421         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3422         if (!ret && oact) {
3423                 sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3424                 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
3425                                &oact->sa_handler);
3426                 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3427                 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3428 #ifdef __ARCH_HAS_SA_RESTORER
3429                 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3430                                 &oact->sa_restorer);
3431 #endif
3432         }
3433         return ret;
3434 }
3435 #endif
3436 #endif /* !CONFIG_ODD_RT_SIGACTION */
3437 
3438 #ifdef CONFIG_OLD_SIGACTION
3439 SYSCALL_DEFINE3(sigaction, int, sig,
3440                 const struct old_sigaction __user *, act,
3441                 struct old_sigaction __user *, oact)
3442 {
3443         struct k_sigaction new_ka, old_ka;
3444         int ret;
3445 
3446         if (act) {
3447                 old_sigset_t mask;
3448                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3449                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3450                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3451                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3452                     __get_user(mask, &act->sa_mask))
3453                         return -EFAULT;
3454 #ifdef __ARCH_HAS_KA_RESTORER
3455                 new_ka.ka_restorer = NULL;
3456 #endif
3457                 siginitset(&new_ka.sa.sa_mask, mask);
3458         }
3459 
3460         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3461 
3462         if (!ret && oact) {
3463                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3464                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3465                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3466                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3467                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3468                         return -EFAULT;
3469         }
3470 
3471         return ret;
3472 }
3473 #endif
3474 #ifdef CONFIG_COMPAT_OLD_SIGACTION
3475 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3476                 const struct compat_old_sigaction __user *, act,
3477                 struct compat_old_sigaction __user *, oact)
3478 {
3479         struct k_sigaction new_ka, old_ka;
3480         int ret;
3481         compat_old_sigset_t mask;
3482         compat_uptr_t handler, restorer;
3483 
3484         if (act) {
3485                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3486                     __get_user(handler, &act->sa_handler) ||
3487                     __get_user(restorer, &act->sa_restorer) ||
3488                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3489                     __get_user(mask, &act->sa_mask))
3490                         return -EFAULT;
3491 
3492 #ifdef __ARCH_HAS_KA_RESTORER
3493                 new_ka.ka_restorer = NULL;
3494 #endif
3495                 new_ka.sa.sa_handler = compat_ptr(handler);
3496                 new_ka.sa.sa_restorer = compat_ptr(restorer);
3497                 siginitset(&new_ka.sa.sa_mask, mask);
3498         }
3499 
3500         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3501 
3502         if (!ret && oact) {
3503                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3504                     __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3505                                &oact->sa_handler) ||
3506                     __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3507                                &oact->sa_restorer) ||
3508                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3509                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3510                         return -EFAULT;
3511         }
3512         return ret;
3513 }
3514 #endif
3515 
3516 #ifdef CONFIG_SGETMASK_SYSCALL
3517 
3518 /*
3519  * For backwards compatibility.  Functionality superseded by sigprocmask.
3520  */
3521 SYSCALL_DEFINE0(sgetmask)
3522 {
3523         /* SMP safe */
3524         return current->blocked.sig[0];
3525 }
3526 
3527 SYSCALL_DEFINE1(ssetmask, int, newmask)
3528 {
3529         int old = current->blocked.sig[0];
3530         sigset_t newset;
3531 
3532         siginitset(&newset, newmask);
3533         set_current_blocked(&newset);
3534 
3535         return old;
3536 }
3537 #endif /* CONFIG_SGETMASK_SYSCALL */
3538 
3539 #ifdef __ARCH_WANT_SYS_SIGNAL
3540 /*
3541  * For backwards compatibility.  Functionality superseded by sigaction.
3542  */
3543 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3544 {
3545         struct k_sigaction new_sa, old_sa;
3546         int ret;
3547 
3548         new_sa.sa.sa_handler = handler;
3549         new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3550         sigemptyset(&new_sa.sa.sa_mask);
3551 
3552         ret = do_sigaction(sig, &new_sa, &old_sa);
3553 
3554         return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3555 }
3556 #endif /* __ARCH_WANT_SYS_SIGNAL */
3557 
3558 #ifdef __ARCH_WANT_SYS_PAUSE
3559 
3560 SYSCALL_DEFINE0(pause)
3561 {
3562         while (!signal_pending(current)) {
3563                 __set_current_state(TASK_INTERRUPTIBLE);
3564                 schedule();
3565         }
3566         return -ERESTARTNOHAND;
3567 }
3568 
3569 #endif
3570 
3571 int sigsuspend(sigset_t *set)
3572 {
3573         current->saved_sigmask = current->blocked;
3574         set_current_blocked(set);
3575 
3576         __set_current_state(TASK_INTERRUPTIBLE);
3577         schedule();
3578         set_restore_sigmask();
3579         return -ERESTARTNOHAND;
3580 }
3581 
3582 /**
3583  *  sys_rt_sigsuspend - replace the signal mask for a value with the
3584  *      @unewset value until a signal is received
3585  *  @unewset: new signal mask value
3586  *  @sigsetsize: size of sigset_t type
3587  */
3588 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3589 {
3590         sigset_t newset;
3591 
3592         /* XXX: Don't preclude handling different sized sigset_t's.  */
3593         if (sigsetsize != sizeof(sigset_t))
3594                 return -EINVAL;
3595 
3596         if (copy_from_user(&newset, unewset, sizeof(newset)))
3597                 return -EFAULT;
3598         return sigsuspend(&newset);
3599 }
3600  
3601 #ifdef CONFIG_COMPAT
3602 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3603 {
3604 #ifdef __BIG_ENDIAN
3605         sigset_t newset;
3606         compat_sigset_t newset32;
3607 
3608         /* XXX: Don't preclude handling different sized sigset_t's.  */
3609         if (sigsetsize != sizeof(sigset_t))
3610                 return -EINVAL;
3611 
3612         if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3613                 return -EFAULT;
3614         sigset_from_compat(&newset, &newset32);
3615         return sigsuspend(&newset);
3616 #else
3617         /* on little-endian bitmaps don't care about granularity */
3618         return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3619 #endif
3620 }
3621 #endif
3622 
3623 #ifdef CONFIG_OLD_SIGSUSPEND
3624 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3625 {
3626         sigset_t blocked;
3627         siginitset(&blocked, mask);
3628         return sigsuspend(&blocked);
3629 }
3630 #endif
3631 #ifdef CONFIG_OLD_SIGSUSPEND3
3632 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3633 {
3634         sigset_t blocked;
3635         siginitset(&blocked, mask);
3636         return sigsuspend(&blocked);
3637 }
3638 #endif
3639 
3640 __weak const char *arch_vma_name(struct vm_area_struct *vma)
3641 {
3642         return NULL;
3643 }
3644 
3645 void __init signals_init(void)
3646 {
3647         sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3648 }
3649 
3650 #ifdef CONFIG_KGDB_KDB
3651 #include <linux/kdb.h>
3652 /*
3653  * kdb_send_sig_info - Allows kdb to send signals without exposing
3654  * signal internals.  This function checks if the required locks are
3655  * available before calling the main signal code, to avoid kdb
3656  * deadlocks.
3657  */
3658 void
3659 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3660 {
3661         static struct task_struct *kdb_prev_t;
3662         int sig, new_t;
3663         if (!spin_trylock(&t->sighand->siglock)) {
3664                 kdb_printf("Can't do kill command now.\n"
3665                            "The sigmask lock is held somewhere else in "
3666                            "kernel, try again later\n");
3667                 return;
3668         }
3669         spin_unlock(&t->sighand->siglock);
3670         new_t = kdb_prev_t != t;
3671         kdb_prev_t = t;
3672         if (t->state != TASK_RUNNING && new_t) {
3673                 kdb_printf("Process is not RUNNING, sending a signal from "
3674                            "kdb risks deadlock\n"
3675                            "on the run queue locks. "
3676                            "The signal has _not_ been sent.\n"
3677                            "Reissue the kill command if you want to risk "
3678                            "the deadlock.\n");
3679                 return;
3680         }
3681         sig = info->si_signo;
3682         if (send_sig_info(sig, info, t))
3683                 kdb_printf("Fail to deliver Signal %d to process %d.\n",
3684                            sig, t->pid);
3685         else
3686                 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3687 }
3688 #endif  /* CONFIG_KGDB_KDB */
3689 

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