Root/kernel/signal.c

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

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