linux/kernel/signal.c
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   1/*
   2 *  linux/kernel/signal.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 *
   6 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
   7 *
   8 *  2003-06-02  Jim Houston - Concurrent Computer Corp.
   9 *              Changes to use preallocated sigqueue structures
  10 *              to allow signals to be sent reliably.
  11 */
  12
  13#include <linux/slab.h>
  14#include <linux/export.h>
  15#include <linux/init.h>
  16#include <linux/sched.h>
  17#include <linux/fs.h>
  18#include <linux/tty.h>
  19#include <linux/binfmts.h>
  20#include <linux/coredump.h>
  21#include <linux/security.h>
  22#include <linux/syscalls.h>
  23#include <linux/ptrace.h>
  24#include <linux/signal.h>
  25#include <linux/signalfd.h>
  26#include <linux/ratelimit.h>
  27#include <linux/tracehook.h>
  28#include <linux/capability.h>
  29#include <linux/freezer.h>
  30#include <linux/pid_namespace.h>
  31#include <linux/nsproxy.h>
  32#include <linux/user_namespace.h>
  33#include <linux/uprobes.h>
  34#include <linux/compat.h>
  35#define CREATE_TRACE_POINTS
  36#include <trace/events/signal.h>
  37
  38#include <asm/param.h>
  39#include <asm/uaccess.h>
  40#include <asm/unistd.h>
  41#include <asm/siginfo.h>
  42#include <asm/cacheflush.h>
  43#include "audit.h"      /* audit_signal_info() */
  44
  45/*
  46 * SLAB caches for signal bits.
  47 */
  48
  49static struct kmem_cache *sigqueue_cachep;
  50
  51int print_fatal_signals __read_mostly;
  52
  53static void __user *sig_handler(struct task_struct *t, int sig)
  54{
  55        return t->sighand->action[sig - 1].sa.sa_handler;
  56}
  57
  58static int sig_handler_ignored(void __user *handler, int sig)
  59{
  60        /* Is it explicitly or implicitly ignored? */
  61        return handler == SIG_IGN ||
  62                (handler == SIG_DFL && sig_kernel_ignore(sig));
  63}
  64
  65static int sig_task_ignored(struct task_struct *t, int sig, bool force)
  66{
  67        void __user *handler;
  68
  69        handler = sig_handler(t, sig);
  70
  71        if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
  72                        handler == SIG_DFL && !force)
  73                return 1;
  74
  75        return sig_handler_ignored(handler, sig);
  76}
  77
  78static int sig_ignored(struct task_struct *t, int sig, bool force)
  79{
  80        /*
  81         * Blocked signals are never ignored, since the
  82         * signal handler may change by the time it is
  83         * unblocked.
  84         */
  85        if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
  86                return 0;
  87
  88        if (!sig_task_ignored(t, sig, force))
  89                return 0;
  90
  91        /*
  92         * Tracers may want to know about even ignored signals.
  93         */
  94        return !t->ptrace;
  95}
  96
  97/*
  98 * Re-calculate pending state from the set of locally pending
  99 * signals, globally pending signals, and blocked signals.
 100 */
 101static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
 102{
 103        unsigned long ready;
 104        long i;
 105
 106        switch (_NSIG_WORDS) {
 107        default:
 108                for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
 109                        ready |= signal->sig[i] &~ blocked->sig[i];
 110                break;
 111
 112        case 4: ready  = signal->sig[3] &~ blocked->sig[3];
 113                ready |= signal->sig[2] &~ blocked->sig[2];
 114                ready |= signal->sig[1] &~ blocked->sig[1];
 115                ready |= signal->sig[0] &~ blocked->sig[0];
 116                break;
 117
 118        case 2: ready  = signal->sig[1] &~ blocked->sig[1];
 119                ready |= signal->sig[0] &~ blocked->sig[0];
 120                break;
 121
 122        case 1: ready  = signal->sig[0] &~ blocked->sig[0];
 123        }
 124        return ready != 0;
 125}
 126
 127#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
 128
 129static int recalc_sigpending_tsk(struct task_struct *t)
 130{
 131        if ((t->jobctl & JOBCTL_PENDING_MASK) ||
 132            PENDING(&t->pending, &t->blocked) ||
 133            PENDING(&t->signal->shared_pending, &t->blocked)) {
 134                set_tsk_thread_flag(t, TIF_SIGPENDING);
 135                return 1;
 136        }
 137        /*
 138         * We must never clear the flag in another thread, or in current
 139         * when it's possible the current syscall is returning -ERESTART*.
 140         * So we don't clear it here, and only callers who know they should do.
 141         */
 142        return 0;
 143}
 144
 145/*
 146 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
 147 * This is superfluous when called on current, the wakeup is a harmless no-op.
 148 */
 149void recalc_sigpending_and_wake(struct task_struct *t)
 150{
 151        if (recalc_sigpending_tsk(t))
 152                signal_wake_up(t, 0);
 153}
 154
 155void recalc_sigpending(void)
 156{
 157        if (!recalc_sigpending_tsk(current) && !freezing(current))
 158                clear_thread_flag(TIF_SIGPENDING);
 159
 160}
 161
 162/* Given the mask, find the first available signal that should be serviced. */
 163
 164#define SYNCHRONOUS_MASK \
 165        (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
 166         sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
 167
 168int next_signal(struct sigpending *pending, sigset_t *mask)
 169{
 170        unsigned long i, *s, *m, x;
 171        int sig = 0;
 172
 173        s = pending->signal.sig;
 174        m = mask->sig;
 175
 176        /*
 177         * Handle the first word specially: it contains the
 178         * synchronous signals that need to be dequeued first.
 179         */
 180        x = *s &~ *m;
 181        if (x) {
 182                if (x & SYNCHRONOUS_MASK)
 183                        x &= SYNCHRONOUS_MASK;
 184                sig = ffz(~x) + 1;
 185                return sig;
 186        }
 187
 188        switch (_NSIG_WORDS) {
 189        default:
 190                for (i = 1; i < _NSIG_WORDS; ++i) {
 191                        x = *++s &~ *++m;
 192                        if (!x)
 193                                continue;
 194                        sig = ffz(~x) + i*_NSIG_BPW + 1;
 195                        break;
 196                }
 197                break;
 198
 199        case 2:
 200                x = s[1] &~ m[1];
 201                if (!x)
 202                        break;
 203                sig = ffz(~x) + _NSIG_BPW + 1;
 204                break;
 205
 206        case 1:
 207                /* Nothing to do */
 208                break;
 209        }
 210
 211        return sig;
 212}
 213
 214static inline void print_dropped_signal(int sig)
 215{
 216        static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
 217
 218        if (!print_fatal_signals)
 219                return;
 220
 221        if (!__ratelimit(&ratelimit_state))
 222                return;
 223
 224        printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
 225                                current->comm, current->pid, sig);
 226}
 227
 228/**
 229 * task_set_jobctl_pending - set jobctl pending bits
 230 * @task: target task
 231 * @mask: pending bits to set
 232 *
 233 * Clear @mask from @task->jobctl.  @mask must be subset of
 234 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
 235 * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
 236 * cleared.  If @task is already being killed or exiting, this function
 237 * becomes noop.
 238 *
 239 * CONTEXT:
 240 * Must be called with @task->sighand->siglock held.
 241 *
 242 * RETURNS:
 243 * %true if @mask is set, %false if made noop because @task was dying.
 244 */
 245bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
 246{
 247        BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
 248                        JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
 249        BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
 250
 251        if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
 252                return false;
 253
 254        if (mask & JOBCTL_STOP_SIGMASK)
 255                task->jobctl &= ~JOBCTL_STOP_SIGMASK;
 256
 257        task->jobctl |= mask;
 258        return true;
 259}
 260
 261/**
 262 * task_clear_jobctl_trapping - clear jobctl trapping bit
 263 * @task: target task
 264 *
 265 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
 266 * Clear it and wake up the ptracer.  Note that we don't need any further
 267 * locking.  @task->siglock guarantees that @task->parent points to the
 268 * ptracer.
 269 *
 270 * CONTEXT:
 271 * Must be called with @task->sighand->siglock held.
 272 */
 273void task_clear_jobctl_trapping(struct task_struct *task)
 274{
 275        if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
 276                task->jobctl &= ~JOBCTL_TRAPPING;
 277                wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
 278        }
 279}
 280
 281/**
 282 * task_clear_jobctl_pending - clear jobctl pending bits
 283 * @task: target task
 284 * @mask: pending bits to clear
 285 *
 286 * Clear @mask from @task->jobctl.  @mask must be subset of
 287 * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
 288 * STOP bits are cleared together.
 289 *
 290 * If clearing of @mask leaves no stop or trap pending, this function calls
 291 * task_clear_jobctl_trapping().
 292 *
 293 * CONTEXT:
 294 * Must be called with @task->sighand->siglock held.
 295 */
 296void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
 297{
 298        BUG_ON(mask & ~JOBCTL_PENDING_MASK);
 299
 300        if (mask & JOBCTL_STOP_PENDING)
 301                mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
 302
 303        task->jobctl &= ~mask;
 304
 305        if (!(task->jobctl & JOBCTL_PENDING_MASK))
 306                task_clear_jobctl_trapping(task);
 307}
 308
 309/**
 310 * task_participate_group_stop - participate in a group stop
 311 * @task: task participating in a group stop
 312 *
 313 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
 314 * Group stop states are cleared and the group stop count is consumed if
 315 * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
 316 * stop, the appropriate %SIGNAL_* flags are set.
 317 *
 318 * CONTEXT:
 319 * Must be called with @task->sighand->siglock held.
 320 *
 321 * RETURNS:
 322 * %true if group stop completion should be notified to the parent, %false
 323 * otherwise.
 324 */
 325static bool task_participate_group_stop(struct task_struct *task)
 326{
 327        struct signal_struct *sig = task->signal;
 328        bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
 329
 330        WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
 331
 332        task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
 333
 334        if (!consume)
 335                return false;
 336
 337        if (!WARN_ON_ONCE(sig->group_stop_count == 0))
 338                sig->group_stop_count--;
 339
 340        /*
 341         * Tell the caller to notify completion iff we are entering into a
 342         * fresh group stop.  Read comment in do_signal_stop() for details.
 343         */
 344        if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
 345                sig->flags = SIGNAL_STOP_STOPPED;
 346                return true;
 347        }
 348        return false;
 349}
 350
 351/*
 352 * allocate a new signal queue record
 353 * - this may be called without locks if and only if t == current, otherwise an
 354 *   appropriate lock must be held to stop the target task from exiting
 355 */
 356static struct sigqueue *
 357__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
 358{
 359        struct sigqueue *q = NULL;
 360        struct user_struct *user;
 361
 362        /*
 363         * Protect access to @t credentials. This can go away when all
 364         * callers hold rcu read lock.
 365         */
 366        rcu_read_lock();
 367        user = get_uid(__task_cred(t)->user);
 368        atomic_inc(&user->sigpending);
 369        rcu_read_unlock();
 370
 371        if (override_rlimit ||
 372            atomic_read(&user->sigpending) <=
 373                        task_rlimit(t, RLIMIT_SIGPENDING)) {
 374                q = kmem_cache_alloc(sigqueue_cachep, flags);
 375        } else {
 376                print_dropped_signal(sig);
 377        }
 378
 379        if (unlikely(q == NULL)) {
 380                atomic_dec(&user->sigpending);
 381                free_uid(user);
 382        } else {
 383                INIT_LIST_HEAD(&q->list);
 384                q->flags = 0;
 385                q->user = user;
 386        }
 387
 388        return q;
 389}
 390
 391static void __sigqueue_free(struct sigqueue *q)
 392{
 393        if (q->flags & SIGQUEUE_PREALLOC)
 394                return;
 395        atomic_dec(&q->user->sigpending);
 396        free_uid(q->user);
 397        kmem_cache_free(sigqueue_cachep, q);
 398}
 399
 400void flush_sigqueue(struct sigpending *queue)
 401{
 402        struct sigqueue *q;
 403
 404        sigemptyset(&queue->signal);
 405        while (!list_empty(&queue->list)) {
 406                q = list_entry(queue->list.next, struct sigqueue , list);
 407                list_del_init(&q->list);
 408                __sigqueue_free(q);
 409        }
 410}
 411
 412/*
 413 * Flush all pending signals for a task.
 414 */
 415void __flush_signals(struct task_struct *t)
 416{
 417        clear_tsk_thread_flag(t, TIF_SIGPENDING);
 418        flush_sigqueue(&t->pending);
 419        flush_sigqueue(&t->signal->shared_pending);
 420}
 421
 422void flush_signals(struct task_struct *t)
 423{
 424        unsigned long flags;
 425
 426        spin_lock_irqsave(&t->sighand->siglock, flags);
 427        __flush_signals(t);
 428        spin_unlock_irqrestore(&t->sighand->siglock, flags);
 429}
 430
 431static void __flush_itimer_signals(struct sigpending *pending)
 432{
 433        sigset_t signal, retain;
 434        struct sigqueue *q, *n;
 435
 436        signal = pending->signal;
 437        sigemptyset(&retain);
 438
 439        list_for_each_entry_safe(q, n, &pending->list, list) {
 440                int sig = q->info.si_signo;
 441
 442                if (likely(q->info.si_code != SI_TIMER)) {
 443                        sigaddset(&retain, sig);
 444                } else {
 445                        sigdelset(&signal, sig);
 446                        list_del_init(&q->list);
 447                        __sigqueue_free(q);
 448                }
 449        }
 450
 451        sigorsets(&pending->signal, &signal, &retain);
 452}
 453
 454void flush_itimer_signals(void)
 455{
 456        struct task_struct *tsk = current;
 457        unsigned long flags;
 458
 459        spin_lock_irqsave(&tsk->sighand->siglock, flags);
 460        __flush_itimer_signals(&tsk->pending);
 461        __flush_itimer_signals(&tsk->signal->shared_pending);
 462        spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 463}
 464
 465void ignore_signals(struct task_struct *t)
 466{
 467        int i;
 468
 469        for (i = 0; i < _NSIG; ++i)
 470                t->sighand->action[i].sa.sa_handler = SIG_IGN;
 471
 472        flush_signals(t);
 473}
 474
 475/*
 476 * Flush all handlers for a task.
 477 */
 478
 479void
 480flush_signal_handlers(struct task_struct *t, int force_default)
 481{
 482        int i;
 483        struct k_sigaction *ka = &t->sighand->action[0];
 484        for (i = _NSIG ; i != 0 ; i--) {
 485                if (force_default || ka->sa.sa_handler != SIG_IGN)
 486                        ka->sa.sa_handler = SIG_DFL;
 487                ka->sa.sa_flags = 0;
 488#ifdef __ARCH_HAS_SA_RESTORER
 489                ka->sa.sa_restorer = NULL;
 490#endif
 491                sigemptyset(&ka->sa.sa_mask);
 492                ka++;
 493        }
 494}
 495
 496int unhandled_signal(struct task_struct *tsk, int sig)
 497{
 498        void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
 499        if (is_global_init(tsk))
 500                return 1;
 501        if (handler != SIG_IGN && handler != SIG_DFL)
 502                return 0;
 503        /* if ptraced, let the tracer determine */
 504        return !tsk->ptrace;
 505}
 506
 507/*
 508 * Notify the system that a driver wants to block all signals for this
 509 * process, and wants to be notified if any signals at all were to be
 510 * sent/acted upon.  If the notifier routine returns non-zero, then the
 511 * signal will be acted upon after all.  If the notifier routine returns 0,
 512 * then then signal will be blocked.  Only one block per process is
 513 * allowed.  priv is a pointer to private data that the notifier routine
 514 * can use to determine if the signal should be blocked or not.
 515 */
 516void
 517block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
 518{
 519        unsigned long flags;
 520
 521        spin_lock_irqsave(&current->sighand->siglock, flags);
 522        current->notifier_mask = mask;
 523        current->notifier_data = priv;
 524        current->notifier = notifier;
 525        spin_unlock_irqrestore(&current->sighand->siglock, flags);
 526}
 527
 528/* Notify the system that blocking has ended. */
 529
 530void
 531unblock_all_signals(void)
 532{
 533        unsigned long flags;
 534
 535        spin_lock_irqsave(&current->sighand->siglock, flags);
 536        current->notifier = NULL;
 537        current->notifier_data = NULL;
 538        recalc_sigpending();
 539        spin_unlock_irqrestore(&current->sighand->siglock, flags);
 540}
 541
 542static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
 543{
 544        struct sigqueue *q, *first = NULL;
 545
 546        /*
 547         * Collect the siginfo appropriate to this signal.  Check if
 548         * there is another siginfo for the same signal.
 549        */
 550        list_for_each_entry(q, &list->list, list) {
 551                if (q->info.si_signo == sig) {
 552                        if (first)
 553                                goto still_pending;
 554                        first = q;
 555                }
 556        }
 557
 558        sigdelset(&list->signal, sig);
 559
 560        if (first) {
 561still_pending:
 562                list_del_init(&first->list);
 563                copy_siginfo(info, &first->info);
 564                __sigqueue_free(first);
 565        } else {
 566                /*
 567                 * Ok, it wasn't in the queue.  This must be
 568                 * a fast-pathed signal or we must have been
 569                 * out of queue space.  So zero out the info.
 570                 */
 571                info->si_signo = sig;
 572                info->si_errno = 0;
 573                info->si_code = SI_USER;
 574                info->si_pid = 0;
 575                info->si_uid = 0;
 576        }
 577}
 578
 579static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
 580                        siginfo_t *info)
 581{
 582        int sig = next_signal(pending, mask);
 583
 584        if (sig) {
 585                if (current->notifier) {
 586                        if (sigismember(current->notifier_mask, sig)) {
 587                                if (!(current->notifier)(current->notifier_data)) {
 588                                        clear_thread_flag(TIF_SIGPENDING);
 589                                        return 0;
 590                                }
 591                        }
 592                }
 593
 594                collect_signal(sig, pending, info);
 595        }
 596
 597        return sig;
 598}
 599
 600/*
 601 * Dequeue a signal and return the element to the caller, which is
 602 * expected to free it.
 603 *
 604 * All callers have to hold the siglock.
 605 */
 606int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
 607{
 608        int signr;
 609
 610        /* We only dequeue private signals from ourselves, we don't let
 611         * signalfd steal them
 612         */
 613        signr = __dequeue_signal(&tsk->pending, mask, info);
 614        if (!signr) {
 615                signr = __dequeue_signal(&tsk->signal->shared_pending,
 616                                         mask, info);
 617                /*
 618                 * itimer signal ?
 619                 *
 620                 * itimers are process shared and we restart periodic
 621                 * itimers in the signal delivery path to prevent DoS
 622                 * attacks in the high resolution timer case. This is
 623                 * compliant with the old way of self-restarting
 624                 * itimers, as the SIGALRM is a legacy signal and only
 625                 * queued once. Changing the restart behaviour to
 626                 * restart the timer in the signal dequeue path is
 627                 * reducing the timer noise on heavy loaded !highres
 628                 * systems too.
 629                 */
 630                if (unlikely(signr == SIGALRM)) {
 631                        struct hrtimer *tmr = &tsk->signal->real_timer;
 632
 633                        if (!hrtimer_is_queued(tmr) &&
 634                            tsk->signal->it_real_incr.tv64 != 0) {
 635                                hrtimer_forward(tmr, tmr->base->get_time(),
 636                                                tsk->signal->it_real_incr);
 637                                hrtimer_restart(tmr);
 638                        }
 639                }
 640        }
 641
 642        recalc_sigpending();
 643        if (!signr)
 644                return 0;
 645
 646        if (unlikely(sig_kernel_stop(signr))) {
 647                /*
 648                 * Set a marker that we have dequeued a stop signal.  Our
 649                 * caller might release the siglock and then the pending
 650                 * stop signal it is about to process is no longer in the
 651                 * pending bitmasks, but must still be cleared by a SIGCONT
 652                 * (and overruled by a SIGKILL).  So those cases clear this
 653                 * shared flag after we've set it.  Note that this flag may
 654                 * remain set after the signal we return is ignored or
 655                 * handled.  That doesn't matter because its only purpose
 656                 * is to alert stop-signal processing code when another
 657                 * processor has come along and cleared the flag.
 658                 */
 659                current->jobctl |= JOBCTL_STOP_DEQUEUED;
 660        }
 661        if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
 662                /*
 663                 * Release the siglock to ensure proper locking order
 664                 * of timer locks outside of siglocks.  Note, we leave
 665                 * irqs disabled here, since the posix-timers code is
 666                 * about to disable them again anyway.
 667                 */
 668                spin_unlock(&tsk->sighand->siglock);
 669                do_schedule_next_timer(info);
 670                spin_lock(&tsk->sighand->siglock);
 671        }
 672        return signr;
 673}
 674
 675/*
 676 * Tell a process that it has a new active signal..
 677 *
 678 * NOTE! we rely on the previous spin_lock to
 679 * lock interrupts for us! We can only be called with
 680 * "siglock" held, and the local interrupt must
 681 * have been disabled when that got acquired!
 682 *
 683 * No need to set need_resched since signal event passing
 684 * goes through ->blocked
 685 */
 686void signal_wake_up_state(struct task_struct *t, unsigned int state)
 687{
 688        set_tsk_thread_flag(t, TIF_SIGPENDING);
 689        /*
 690         * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
 691         * case. We don't check t->state here because there is a race with it
 692         * executing another processor and just now entering stopped state.
 693         * By using wake_up_state, we ensure the process will wake up and
 694         * handle its death signal.
 695         */
 696        if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
 697                kick_process(t);
 698}
 699
 700/*
 701 * Remove signals in mask from the pending set and queue.
 702 * Returns 1 if any signals were found.
 703 *
 704 * All callers must be holding the siglock.
 705 *
 706 * This version takes a sigset mask and looks at all signals,
 707 * not just those in the first mask word.
 708 */
 709static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
 710{
 711        struct sigqueue *q, *n;
 712        sigset_t m;
 713
 714        sigandsets(&m, mask, &s->signal);
 715        if (sigisemptyset(&m))
 716                return 0;
 717
 718        sigandnsets(&s->signal, &s->signal, mask);
 719        list_for_each_entry_safe(q, n, &s->list, list) {
 720                if (sigismember(mask, q->info.si_signo)) {
 721                        list_del_init(&q->list);
 722                        __sigqueue_free(q);
 723                }
 724        }
 725        return 1;
 726}
 727/*
 728 * Remove signals in mask from the pending set and queue.
 729 * Returns 1 if any signals were found.
 730 *
 731 * All callers must be holding the siglock.
 732 */
 733static int rm_from_queue(unsigned long mask, struct sigpending *s)
 734{
 735        struct sigqueue *q, *n;
 736
 737        if (!sigtestsetmask(&s->signal, mask))
 738                return 0;
 739
 740        sigdelsetmask(&s->signal, mask);
 741        list_for_each_entry_safe(q, n, &s->list, list) {
 742                if (q->info.si_signo < SIGRTMIN &&
 743                    (mask & sigmask(q->info.si_signo))) {
 744                        list_del_init(&q->list);
 745                        __sigqueue_free(q);
 746                }
 747        }
 748        return 1;
 749}
 750
 751static inline int is_si_special(const struct siginfo *info)
 752{
 753        return info <= SEND_SIG_FORCED;
 754}
 755
 756static inline bool si_fromuser(const struct siginfo *info)
 757{
 758        return info == SEND_SIG_NOINFO ||
 759                (!is_si_special(info) && SI_FROMUSER(info));
 760}
 761
 762/*
 763 * called with RCU read lock from check_kill_permission()
 764 */
 765static int kill_ok_by_cred(struct task_struct *t)
 766{
 767        const struct cred *cred = current_cred();
 768        const struct cred *tcred = __task_cred(t);
 769
 770        if (uid_eq(cred->euid, tcred->suid) ||
 771            uid_eq(cred->euid, tcred->uid)  ||
 772            uid_eq(cred->uid,  tcred->suid) ||
 773            uid_eq(cred->uid,  tcred->uid))
 774                return 1;
 775
 776        if (ns_capable(tcred->user_ns, CAP_KILL))
 777                return 1;
 778
 779        return 0;
 780}
 781
 782/*
 783 * Bad permissions for sending the signal
 784 * - the caller must hold the RCU read lock
 785 */
 786static int check_kill_permission(int sig, struct siginfo *info,
 787                                 struct task_struct *t)
 788{
 789        struct pid *sid;
 790        int error;
 791
 792        if (!valid_signal(sig))
 793                return -EINVAL;
 794
 795        if (!si_fromuser(info))
 796                return 0;
 797
 798        error = audit_signal_info(sig, t); /* Let audit system see the signal */
 799        if (error)
 800                return error;
 801
 802        if (!same_thread_group(current, t) &&
 803            !kill_ok_by_cred(t)) {
 804                switch (sig) {
 805                case SIGCONT:
 806                        sid = task_session(t);
 807                        /*
 808                         * We don't return the error if sid == NULL. The
 809                         * task was unhashed, the caller must notice this.
 810                         */
 811                        if (!sid || sid == task_session(current))
 812                                break;
 813                default:
 814                        return -EPERM;
 815                }
 816        }
 817
 818        return security_task_kill(t, info, sig, 0);
 819}
 820
 821/**
 822 * ptrace_trap_notify - schedule trap to notify ptracer
 823 * @t: tracee wanting to notify tracer
 824 *
 825 * This function schedules sticky ptrace trap which is cleared on the next
 826 * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
 827 * ptracer.
 828 *
 829 * If @t is running, STOP trap will be taken.  If trapped for STOP and
 830 * ptracer is listening for events, tracee is woken up so that it can
 831 * re-trap for the new event.  If trapped otherwise, STOP trap will be
 832 * eventually taken without returning to userland after the existing traps
 833 * are finished by PTRACE_CONT.
 834 *
 835 * CONTEXT:
 836 * Must be called with @task->sighand->siglock held.
 837 */
 838static void ptrace_trap_notify(struct task_struct *t)
 839{
 840        WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
 841        assert_spin_locked(&t->sighand->siglock);
 842
 843        task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
 844        ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
 845}
 846
 847/*
 848 * Handle magic process-wide effects of stop/continue signals. Unlike
 849 * the signal actions, these happen immediately at signal-generation
 850 * time regardless of blocking, ignoring, or handling.  This does the
 851 * actual continuing for SIGCONT, but not the actual stopping for stop
 852 * signals. The process stop is done as a signal action for SIG_DFL.
 853 *
 854 * Returns true if the signal should be actually delivered, otherwise
 855 * it should be dropped.
 856 */
 857static int prepare_signal(int sig, struct task_struct *p, bool force)
 858{
 859        struct signal_struct *signal = p->signal;
 860        struct task_struct *t;
 861
 862        if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
 863                /*
 864                 * The process is in the middle of dying, nothing to do.
 865                 */
 866        } else if (sig_kernel_stop(sig)) {
 867                /*
 868                 * This is a stop signal.  Remove SIGCONT from all queues.
 869                 */
 870                rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
 871                t = p;
 872                do {
 873                        rm_from_queue(sigmask(SIGCONT), &t->pending);
 874                } while_each_thread(p, t);
 875        } else if (sig == SIGCONT) {
 876                unsigned int why;
 877                /*
 878                 * Remove all stop signals from all queues, wake all threads.
 879                 */
 880                rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
 881                t = p;
 882                do {
 883                        task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
 884                        rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
 885                        if (likely(!(t->ptrace & PT_SEIZED)))
 886                                wake_up_state(t, __TASK_STOPPED);
 887                        else
 888                                ptrace_trap_notify(t);
 889                } while_each_thread(p, t);
 890
 891                /*
 892                 * Notify the parent with CLD_CONTINUED if we were stopped.
 893                 *
 894                 * If we were in the middle of a group stop, we pretend it
 895                 * was already finished, and then continued. Since SIGCHLD
 896                 * doesn't queue we report only CLD_STOPPED, as if the next
 897                 * CLD_CONTINUED was dropped.
 898                 */
 899                why = 0;
 900                if (signal->flags & SIGNAL_STOP_STOPPED)
 901                        why |= SIGNAL_CLD_CONTINUED;
 902                else if (signal->group_stop_count)
 903                        why |= SIGNAL_CLD_STOPPED;
 904
 905                if (why) {
 906                        /*
 907                         * The first thread which returns from do_signal_stop()
 908                         * will take ->siglock, notice SIGNAL_CLD_MASK, and
 909                         * notify its parent. See get_signal_to_deliver().
 910                         */
 911                        signal->flags = why | SIGNAL_STOP_CONTINUED;
 912                        signal->group_stop_count = 0;
 913                        signal->group_exit_code = 0;
 914                }
 915        }
 916
 917        return !sig_ignored(p, sig, force);
 918}
 919
 920/*
 921 * Test if P wants to take SIG.  After we've checked all threads with this,
 922 * it's equivalent to finding no threads not blocking SIG.  Any threads not
 923 * blocking SIG were ruled out because they are not running and already
 924 * have pending signals.  Such threads will dequeue from the shared queue
 925 * as soon as they're available, so putting the signal on the shared queue
 926 * will be equivalent to sending it to one such thread.
 927 */
 928static inline int wants_signal(int sig, struct task_struct *p)
 929{
 930        if (sigismember(&p->blocked, sig))
 931                return 0;
 932        if (p->flags & PF_EXITING)
 933                return 0;
 934        if (sig == SIGKILL)
 935                return 1;
 936        if (task_is_stopped_or_traced(p))
 937                return 0;
 938        return task_curr(p) || !signal_pending(p);
 939}
 940
 941static void complete_signal(int sig, struct task_struct *p, int group)
 942{
 943        struct signal_struct *signal = p->signal;
 944        struct task_struct *t;
 945
 946        /*
 947         * Now find a thread we can wake up to take the signal off the queue.
 948         *
 949         * If the main thread wants the signal, it gets first crack.
 950         * Probably the least surprising to the average bear.
 951         */
 952        if (wants_signal(sig, p))
 953                t = p;
 954        else if (!group || thread_group_empty(p))
 955                /*
 956                 * There is just one thread and it does not need to be woken.
 957                 * It will dequeue unblocked signals before it runs again.
 958                 */
 959                return;
 960        else {
 961                /*
 962                 * Otherwise try to find a suitable thread.
 963                 */
 964                t = signal->curr_target;
 965                while (!wants_signal(sig, t)) {
 966                        t = next_thread(t);
 967                        if (t == signal->curr_target)
 968                                /*
 969                                 * No thread needs to be woken.
 970                                 * Any eligible threads will see
 971                                 * the signal in the queue soon.
 972                                 */
 973                                return;
 974                }
 975                signal->curr_target = t;
 976        }
 977
 978        /*
 979         * Found a killable thread.  If the signal will be fatal,
 980         * then start taking the whole group down immediately.
 981         */
 982        if (sig_fatal(p, sig) &&
 983            !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
 984            !sigismember(&t->real_blocked, sig) &&
 985            (sig == SIGKILL || !t->ptrace)) {
 986                /*
 987                 * This signal will be fatal to the whole group.
 988                 */
 989                if (!sig_kernel_coredump(sig)) {
 990                        /*
 991                         * Start a group exit and wake everybody up.
 992                         * This way we don't have other threads
 993                         * running and doing things after a slower
 994                         * thread has the fatal signal pending.
 995                         */
 996                        signal->flags = SIGNAL_GROUP_EXIT;
 997                        signal->group_exit_code = sig;
 998                        signal->group_stop_count = 0;
 999                        t = p;
1000                        do {
1001                                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1002                                sigaddset(&t->pending.signal, SIGKILL);
1003                                signal_wake_up(t, 1);
1004                        } while_each_thread(p, t);
1005                        return;
1006                }
1007        }
1008
1009        /*
1010         * The signal is already in the shared-pending queue.
1011         * Tell the chosen thread to wake up and dequeue it.
1012         */
1013        signal_wake_up(t, sig == SIGKILL);
1014        return;
1015}
1016
1017static inline int legacy_queue(struct sigpending *signals, int sig)
1018{
1019        return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1020}
1021
1022#ifdef CONFIG_USER_NS
1023static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1024{
1025        if (current_user_ns() == task_cred_xxx(t, user_ns))
1026                return;
1027
1028        if (SI_FROMKERNEL(info))
1029                return;
1030
1031        rcu_read_lock();
1032        info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
1033                                        make_kuid(current_user_ns(), info->si_uid));
1034        rcu_read_unlock();
1035}
1036#else
1037static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
1038{
1039        return;
1040}
1041#endif
1042
1043static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1044                        int group, int from_ancestor_ns)
1045{
1046        struct sigpending *pending;
1047        struct sigqueue *q;
1048        int override_rlimit;
1049        int ret = 0, result;
1050
1051        assert_spin_locked(&t->sighand->siglock);
1052
1053        result = TRACE_SIGNAL_IGNORED;
1054        if (!prepare_signal(sig, t,
1055                        from_ancestor_ns || (info == SEND_SIG_FORCED)))
1056                goto ret;
1057
1058        pending = group ? &t->signal->shared_pending : &t->pending;
1059        /*
1060         * Short-circuit ignored signals and support queuing
1061         * exactly one non-rt signal, so that we can get more
1062         * detailed information about the cause of the signal.
1063         */
1064        result = TRACE_SIGNAL_ALREADY_PENDING;
1065        if (legacy_queue(pending, sig))
1066                goto ret;
1067
1068        result = TRACE_SIGNAL_DELIVERED;
1069        /*
1070         * fast-pathed signals for kernel-internal things like SIGSTOP
1071         * or SIGKILL.
1072         */
1073        if (info == SEND_SIG_FORCED)
1074                goto out_set;
1075
1076        /*
1077         * Real-time signals must be queued if sent by sigqueue, or
1078         * some other real-time mechanism.  It is implementation
1079         * defined whether kill() does so.  We attempt to do so, on
1080         * the principle of least surprise, but since kill is not
1081         * allowed to fail with EAGAIN when low on memory we just
1082         * make sure at least one signal gets delivered and don't
1083         * pass on the info struct.
1084         */
1085        if (sig < SIGRTMIN)
1086                override_rlimit = (is_si_special(info) || info->si_code >= 0);
1087        else
1088                override_rlimit = 0;
1089
1090        q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1091                override_rlimit);
1092        if (q) {
1093                list_add_tail(&q->list, &pending->list);
1094                switch ((unsigned long) info) {
1095                case (unsigned long) SEND_SIG_NOINFO:
1096                        q->info.si_signo = sig;
1097                        q->info.si_errno = 0;
1098                        q->info.si_code = SI_USER;
1099                        q->info.si_pid = task_tgid_nr_ns(current,
1100                                                        task_active_pid_ns(t));
1101                        q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1102                        break;
1103                case (unsigned long) SEND_SIG_PRIV:
1104                        q->info.si_signo = sig;
1105                        q->info.si_errno = 0;
1106                        q->info.si_code = SI_KERNEL;
1107                        q->info.si_pid = 0;
1108                        q->info.si_uid = 0;
1109                        break;
1110                default:
1111                        copy_siginfo(&q->info, info);
1112                        if (from_ancestor_ns)
1113                                q->info.si_pid = 0;
1114                        break;
1115                }
1116
1117                userns_fixup_signal_uid(&q->info, t);
1118
1119        } else if (!is_si_special(info)) {
1120                if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1121                        /*
1122                         * Queue overflow, abort.  We may abort if the
1123                         * signal was rt and sent by user using something
1124                         * other than kill().
1125                         */
1126                        result = TRACE_SIGNAL_OVERFLOW_FAIL;
1127                        ret = -EAGAIN;
1128                        goto ret;
1129                } else {
1130                        /*
1131                         * This is a silent loss of information.  We still
1132                         * send the signal, but the *info bits are lost.
1133                         */
1134                        result = TRACE_SIGNAL_LOSE_INFO;
1135                }
1136        }
1137
1138out_set:
1139        signalfd_notify(t, sig);
1140        sigaddset(&pending->signal, sig);
1141        complete_signal(sig, t, group);
1142ret:
1143        trace_signal_generate(sig, info, t, group, result);
1144        return ret;
1145}
1146
1147static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1148                        int group)
1149{
1150        int from_ancestor_ns = 0;
1151
1152#ifdef CONFIG_PID_NS
1153        from_ancestor_ns = si_fromuser(info) &&
1154                           !task_pid_nr_ns(current, task_active_pid_ns(t));
1155#endif
1156
1157        return __send_signal(sig, info, t, group, from_ancestor_ns);
1158}
1159
1160static void print_fatal_signal(int signr)
1161{
1162        struct pt_regs *regs = signal_pt_regs();
1163        printk(KERN_INFO "%s/%d: potentially unexpected fatal signal %d.\n",
1164                current->comm, task_pid_nr(current), signr);
1165
1166#if defined(__i386__) && !defined(__arch_um__)
1167        printk(KERN_INFO "code at %08lx: ", regs->ip);
1168        {
1169                int i;
1170                for (i = 0; i < 16; i++) {
1171                        unsigned char insn;
1172
1173                        if (get_user(insn, (unsigned char *)(regs->ip + i)))
1174                                break;
1175                        printk(KERN_CONT "%02x ", insn);
1176                }
1177        }
1178        printk(KERN_CONT "\n");
1179#endif
1180        preempt_disable();
1181        show_regs(regs);
1182        preempt_enable();
1183}
1184
1185static int __init setup_print_fatal_signals(char *str)
1186{
1187        get_option (&str, &print_fatal_signals);
1188
1189        return 1;
1190}
1191
1192__setup("print-fatal-signals=", setup_print_fatal_signals);
1193
1194int
1195__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1196{
1197        return send_signal(sig, info, p, 1);
1198}
1199
1200static int
1201specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1202{
1203        return send_signal(sig, info, t, 0);
1204}
1205
1206int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1207                        bool group)
1208{
1209        unsigned long flags;
1210        int ret = -ESRCH;
1211
1212        if (lock_task_sighand(p, &flags)) {
1213                ret = send_signal(sig, info, p, group);
1214                unlock_task_sighand(p, &flags);
1215        }
1216
1217        return ret;
1218}
1219
1220/*
1221 * Force a signal that the process can't ignore: if necessary
1222 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1223 *
1224 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1225 * since we do not want to have a signal handler that was blocked
1226 * be invoked when user space had explicitly blocked it.
1227 *
1228 * We don't want to have recursive SIGSEGV's etc, for example,
1229 * that is why we also clear SIGNAL_UNKILLABLE.
1230 */
1231int
1232force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1233{
1234        unsigned long int flags;
1235        int ret, blocked, ignored;
1236        struct k_sigaction *action;
1237
1238        spin_lock_irqsave(&t->sighand->siglock, flags);
1239        action = &t->sighand->action[sig-1];
1240        ignored = action->sa.sa_handler == SIG_IGN;
1241        blocked = sigismember(&t->blocked, sig);
1242        if (blocked || ignored) {
1243                action->sa.sa_handler = SIG_DFL;
1244                if (blocked) {
1245                        sigdelset(&t->blocked, sig);
1246                        recalc_sigpending_and_wake(t);
1247                }
1248        }
1249        if (action->sa.sa_handler == SIG_DFL)
1250                t->signal->flags &= ~SIGNAL_UNKILLABLE;
1251        ret = specific_send_sig_info(sig, info, t);
1252        spin_unlock_irqrestore(&t->sighand->siglock, flags);
1253
1254        return ret;
1255}
1256
1257/*
1258 * Nuke all other threads in the group.
1259 */
1260int zap_other_threads(struct task_struct *p)
1261{
1262        struct task_struct *t = p;
1263        int count = 0;
1264
1265        p->signal->group_stop_count = 0;
1266
1267        while_each_thread(p, t) {
1268                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1269                count++;
1270
1271                /* Don't bother with already dead threads */
1272                if (t->exit_state)
1273                        continue;
1274                sigaddset(&t->pending.signal, SIGKILL);
1275                signal_wake_up(t, 1);
1276        }
1277
1278        return count;
1279}
1280
1281struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1282                                           unsigned long *flags)
1283{
1284        struct sighand_struct *sighand;
1285
1286        for (;;) {
1287                local_irq_save(*flags);
1288                rcu_read_lock();
1289                sighand = rcu_dereference(tsk->sighand);
1290                if (unlikely(sighand == NULL)) {
1291                        rcu_read_unlock();
1292                        local_irq_restore(*flags);
1293                        break;
1294                }
1295
1296                spin_lock(&sighand->siglock);
1297                if (likely(sighand == tsk->sighand)) {
1298                        rcu_read_unlock();
1299                        break;
1300                }
1301                spin_unlock(&sighand->siglock);
1302                rcu_read_unlock();
1303                local_irq_restore(*flags);
1304        }
1305
1306        return sighand;
1307}
1308
1309/*
1310 * send signal info to all the members of a group
1311 */
1312int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1313{
1314        int ret;
1315
1316        rcu_read_lock();
1317        ret = check_kill_permission(sig, info, p);
1318        rcu_read_unlock();
1319
1320        if (!ret && sig)
1321                ret = do_send_sig_info(sig, info, p, true);
1322
1323        return ret;
1324}
1325
1326/*
1327 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1328 * control characters do (^C, ^Z etc)
1329 * - the caller must hold at least a readlock on tasklist_lock
1330 */
1331int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1332{
1333        struct task_struct *p = NULL;
1334        int retval, success;
1335
1336        success = 0;
1337        retval = -ESRCH;
1338        do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1339                int err = group_send_sig_info(sig, info, p);
1340                success |= !err;
1341                retval = err;
1342        } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1343        return success ? 0 : retval;
1344}
1345
1346int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1347{
1348        int error = -ESRCH;
1349        struct task_struct *p;
1350
1351        rcu_read_lock();
1352retry:
1353        p = pid_task(pid, PIDTYPE_PID);
1354        if (p) {
1355                error = group_send_sig_info(sig, info, p);
1356                if (unlikely(error == -ESRCH))
1357                        /*
1358                         * The task was unhashed in between, try again.
1359                         * If it is dead, pid_task() will return NULL,
1360                         * if we race with de_thread() it will find the
1361                         * new leader.
1362                         */
1363                        goto retry;
1364        }
1365        rcu_read_unlock();
1366
1367        return error;
1368}
1369
1370int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1371{
1372        int error;
1373        rcu_read_lock();
1374        error = kill_pid_info(sig, info, find_vpid(pid));
1375        rcu_read_unlock();
1376        return error;
1377}
1378
1379static int kill_as_cred_perm(const struct cred *cred,
1380                             struct task_struct *target)
1381{
1382        const struct cred *pcred = __task_cred(target);
1383        if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1384            !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
1385                return 0;
1386        return 1;
1387}
1388
1389/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1390int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1391                         const struct cred *cred, u32 secid)
1392{
1393        int ret = -EINVAL;
1394        struct task_struct *p;
1395        unsigned long flags;
1396
1397        if (!valid_signal(sig))
1398                return ret;
1399
1400        rcu_read_lock();
1401        p = pid_task(pid, PIDTYPE_PID);
1402        if (!p) {
1403                ret = -ESRCH;
1404                goto out_unlock;
1405        }
1406        if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1407                ret = -EPERM;
1408                goto out_unlock;
1409        }
1410        ret = security_task_kill(p, info, sig, secid);
1411        if (ret)
1412                goto out_unlock;
1413
1414        if (sig) {
1415                if (lock_task_sighand(p, &flags)) {
1416                        ret = __send_signal(sig, info, p, 1, 0);
1417                        unlock_task_sighand(p, &flags);
1418                } else
1419                        ret = -ESRCH;
1420        }
1421out_unlock:
1422        rcu_read_unlock();
1423        return ret;
1424}
1425EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1426
1427/*
1428 * kill_something_info() interprets pid in interesting ways just like kill(2).
1429 *
1430 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1431 * is probably wrong.  Should make it like BSD or SYSV.
1432 */
1433
1434static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1435{
1436        int ret;
1437
1438        if (pid > 0) {
1439                rcu_read_lock();
1440                ret = kill_pid_info(sig, info, find_vpid(pid));
1441                rcu_read_unlock();
1442                return ret;
1443        }
1444
1445        read_lock(&tasklist_lock);
1446        if (pid != -1) {
1447                ret = __kill_pgrp_info(sig, info,
1448                                pid ? find_vpid(-pid) : task_pgrp(current));
1449        } else {
1450                int retval = 0, count = 0;
1451                struct task_struct * p;
1452
1453                for_each_process(p) {
1454                        if (task_pid_vnr(p) > 1 &&
1455                                        !same_thread_group(p, current)) {
1456                                int err = group_send_sig_info(sig, info, p);
1457                                ++count;
1458                                if (err != -EPERM)
1459                                        retval = err;
1460                        }
1461                }
1462                ret = count ? retval : -ESRCH;
1463        }
1464        read_unlock(&tasklist_lock);
1465
1466        return ret;
1467}
1468
1469/*
1470 * These are for backward compatibility with the rest of the kernel source.
1471 */
1472
1473int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1474{
1475        /*
1476         * Make sure legacy kernel users don't send in bad values
1477         * (normal paths check this in check_kill_permission).
1478         */
1479        if (!valid_signal(sig))
1480                return -EINVAL;
1481
1482        return do_send_sig_info(sig, info, p, false);
1483}
1484
1485#define __si_special(priv) \
1486        ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1487
1488int
1489send_sig(int sig, struct task_struct *p, int priv)
1490{
1491        return send_sig_info(sig, __si_special(priv), p);
1492}
1493
1494void
1495force_sig(int sig, struct task_struct *p)
1496{
1497        force_sig_info(sig, SEND_SIG_PRIV, p);
1498}
1499
1500/*
1501 * When things go south during signal handling, we
1502 * will force a SIGSEGV. And if the signal that caused
1503 * the problem was already a SIGSEGV, we'll want to
1504 * make sure we don't even try to deliver the signal..
1505 */
1506int
1507force_sigsegv(int sig, struct task_struct *p)
1508{
1509        if (sig == SIGSEGV) {
1510                unsigned long flags;
1511                spin_lock_irqsave(&p->sighand->siglock, flags);
1512                p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1513                spin_unlock_irqrestore(&p->sighand->siglock, flags);
1514        }
1515        force_sig(SIGSEGV, p);
1516        return 0;
1517}
1518
1519int kill_pgrp(struct pid *pid, int sig, int priv)
1520{
1521        int ret;
1522
1523        read_lock(&tasklist_lock);
1524        ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1525        read_unlock(&tasklist_lock);
1526
1527        return ret;
1528}
1529EXPORT_SYMBOL(kill_pgrp);
1530
1531int kill_pid(struct pid *pid, int sig, int priv)
1532{
1533        return kill_pid_info(sig, __si_special(priv), pid);
1534}
1535EXPORT_SYMBOL(kill_pid);
1536
1537/*
1538 * These functions support sending signals using preallocated sigqueue
1539 * structures.  This is needed "because realtime applications cannot
1540 * afford to lose notifications of asynchronous events, like timer
1541 * expirations or I/O completions".  In the case of POSIX Timers
1542 * we allocate the sigqueue structure from the timer_create.  If this
1543 * allocation fails we are able to report the failure to the application
1544 * with an EAGAIN error.
1545 */
1546struct sigqueue *sigqueue_alloc(void)
1547{
1548        struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1549
1550        if (q)
1551                q->flags |= SIGQUEUE_PREALLOC;
1552
1553        return q;
1554}
1555
1556void sigqueue_free(struct sigqueue *q)
1557{
1558        unsigned long flags;
1559        spinlock_t *lock = &current->sighand->siglock;
1560
1561        BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1562        /*
1563         * We must hold ->siglock while testing q->list
1564         * to serialize with collect_signal() or with
1565         * __exit_signal()->flush_sigqueue().
1566         */
1567        spin_lock_irqsave(lock, flags);
1568        q->flags &= ~SIGQUEUE_PREALLOC;
1569        /*
1570         * If it is queued it will be freed when dequeued,
1571         * like the "regular" sigqueue.
1572         */
1573        if (!list_empty(&q->list))
1574                q = NULL;
1575        spin_unlock_irqrestore(lock, flags);
1576
1577        if (q)
1578                __sigqueue_free(q);
1579}
1580
1581int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1582{
1583        int sig = q->info.si_signo;
1584        struct sigpending *pending;
1585        unsigned long flags;
1586        int ret, result;
1587
1588        BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1589
1590        ret = -1;
1591        if (!likely(lock_task_sighand(t, &flags)))
1592                goto ret;
1593
1594        ret = 1; /* the signal is ignored */
1595        result = TRACE_SIGNAL_IGNORED;
1596        if (!prepare_signal(sig, t, false))
1597                goto out;
1598
1599        ret = 0;
1600        if (unlikely(!list_empty(&q->list))) {
1601                /*
1602                 * If an SI_TIMER entry is already queue just increment
1603                 * the overrun count.
1604                 */
1605                BUG_ON(q->info.si_code != SI_TIMER);
1606                q->info.si_overrun++;
1607                result = TRACE_SIGNAL_ALREADY_PENDING;
1608                goto out;
1609        }
1610        q->info.si_overrun = 0;
1611
1612        signalfd_notify(t, sig);
1613        pending = group ? &t->signal->shared_pending : &t->pending;
1614        list_add_tail(&q->list, &pending->list);
1615        sigaddset(&pending->signal, sig);
1616        complete_signal(sig, t, group);
1617        result = TRACE_SIGNAL_DELIVERED;
1618out:
1619        trace_signal_generate(sig, &q->info, t, group, result);
1620        unlock_task_sighand(t, &flags);
1621ret:
1622        return ret;
1623}
1624
1625/*
1626 * Let a parent know about the death of a child.
1627 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1628 *
1629 * Returns true if our parent ignored us and so we've switched to
1630 * self-reaping.
1631 */
1632bool do_notify_parent(struct task_struct *tsk, int sig)
1633{
1634        struct siginfo info;
1635        unsigned long flags;
1636        struct sighand_struct *psig;
1637        bool autoreap = false;
1638        cputime_t utime, stime;
1639
1640        BUG_ON(sig == -1);
1641
1642        /* do_notify_parent_cldstop should have been called instead.  */
1643        BUG_ON(task_is_stopped_or_traced(tsk));
1644
1645        BUG_ON(!tsk->ptrace &&
1646               (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1647
1648        if (sig != SIGCHLD) {
1649                /*
1650                 * This is only possible if parent == real_parent.
1651                 * Check if it has changed security domain.
1652                 */
1653                if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1654                        sig = SIGCHLD;
1655        }
1656
1657        info.si_signo = sig;
1658        info.si_errno = 0;
1659        /*
1660         * We are under tasklist_lock here so our parent is tied to
1661         * us and cannot change.
1662         *
1663         * task_active_pid_ns will always return the same pid namespace
1664         * until a task passes through release_task.
1665         *
1666         * write_lock() currently calls preempt_disable() which is the
1667         * same as rcu_read_lock(), but according to Oleg, this is not
1668         * correct to rely on this
1669         */
1670        rcu_read_lock();
1671        info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1672        info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1673                                       task_uid(tsk));
1674        rcu_read_unlock();
1675
1676        task_cputime(tsk, &utime, &stime);
1677        info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
1678        info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
1679
1680        info.si_status = tsk->exit_code & 0x7f;
1681        if (tsk->exit_code & 0x80)
1682                info.si_code = CLD_DUMPED;
1683        else if (tsk->exit_code & 0x7f)
1684                info.si_code = CLD_KILLED;
1685        else {
1686                info.si_code = CLD_EXITED;
1687                info.si_status = tsk->exit_code >> 8;
1688        }
1689
1690        psig = tsk->parent->sighand;
1691        spin_lock_irqsave(&psig->siglock, flags);
1692        if (!tsk->ptrace && sig == SIGCHLD &&
1693            (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1694             (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1695                /*
1696                 * We are exiting and our parent doesn't care.  POSIX.1
1697                 * defines special semantics for setting SIGCHLD to SIG_IGN
1698                 * or setting the SA_NOCLDWAIT flag: we should be reaped
1699                 * automatically and not left for our parent's wait4 call.
1700                 * Rather than having the parent do it as a magic kind of
1701                 * signal handler, we just set this to tell do_exit that we
1702                 * can be cleaned up without becoming a zombie.  Note that
1703                 * we still call __wake_up_parent in this case, because a
1704                 * blocked sys_wait4 might now return -ECHILD.
1705                 *
1706                 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1707                 * is implementation-defined: we do (if you don't want
1708                 * it, just use SIG_IGN instead).
1709                 */
1710                autoreap = true;
1711                if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1712                        sig = 0;
1713        }
1714        if (valid_signal(sig) && sig)
1715                __group_send_sig_info(sig, &info, tsk->parent);
1716        __wake_up_parent(tsk, tsk->parent);
1717        spin_unlock_irqrestore(&psig->siglock, flags);
1718
1719        return autoreap;
1720}
1721
1722/**
1723 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1724 * @tsk: task reporting the state change
1725 * @for_ptracer: the notification is for ptracer
1726 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1727 *
1728 * Notify @tsk's parent that the stopped/continued state has changed.  If
1729 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1730 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1731 *
1732 * CONTEXT:
1733 * Must be called with tasklist_lock at least read locked.
1734 */
1735static void do_notify_parent_cldstop(struct task_struct *tsk,
1736                                     bool for_ptracer, int why)
1737{
1738        struct siginfo info;
1739        unsigned long flags;
1740        struct task_struct *parent;
1741        struct sighand_struct *sighand;
1742        cputime_t utime, stime;
1743
1744        if (for_ptracer) {
1745                parent = tsk->parent;
1746        } else {
1747                tsk = tsk->group_leader;
1748                parent = tsk->real_parent;
1749        }
1750
1751        info.si_signo = SIGCHLD;
1752        info.si_errno = 0;
1753        /*
1754         * see comment in do_notify_parent() about the following 4 lines
1755         */
1756        rcu_read_lock();
1757        info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1758        info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1759        rcu_read_unlock();
1760
1761        task_cputime(tsk, &utime, &stime);
1762        info.si_utime = cputime_to_clock_t(utime);
1763        info.si_stime = cputime_to_clock_t(stime);
1764
1765        info.si_code = why;
1766        switch (why) {
1767        case CLD_CONTINUED:
1768                info.si_status = SIGCONT;
1769                break;
1770        case CLD_STOPPED:
1771                info.si_status = tsk->signal->group_exit_code & 0x7f;
1772                break;
1773        case CLD_TRAPPED:
1774                info.si_status = tsk->exit_code & 0x7f;
1775                break;
1776        default:
1777                BUG();
1778        }
1779
1780        sighand = parent->sighand;
1781        spin_lock_irqsave(&sighand->siglock, flags);
1782        if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1783            !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1784                __group_send_sig_info(SIGCHLD, &info, parent);
1785        /*
1786         * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1787         */
1788        __wake_up_parent(tsk, parent);
1789        spin_unlock_irqrestore(&sighand->siglock, flags);
1790}
1791
1792static inline int may_ptrace_stop(void)
1793{
1794        if (!likely(current->ptrace))
1795                return 0;
1796        /*
1797         * Are we in the middle of do_coredump?
1798         * If so and our tracer is also part of the coredump stopping
1799         * is a deadlock situation, and pointless because our tracer
1800         * is dead so don't allow us to stop.
1801         * If SIGKILL was already sent before the caller unlocked
1802         * ->siglock we must see ->core_state != NULL. Otherwise it
1803         * is safe to enter schedule().
1804         *
1805         * This is almost outdated, a task with the pending SIGKILL can't
1806         * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1807         * after SIGKILL was already dequeued.
1808         */
1809        if (unlikely(current->mm->core_state) &&
1810            unlikely(current->mm == current->parent->mm))
1811                return 0;
1812
1813        return 1;
1814}
1815
1816/*
1817 * Return non-zero if there is a SIGKILL that should be waking us up.
1818 * Called with the siglock held.
1819 */
1820static int sigkill_pending(struct task_struct *tsk)
1821{
1822        return  sigismember(&tsk->pending.signal, SIGKILL) ||
1823                sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1824}
1825
1826/*
1827 * This must be called with current->sighand->siglock held.
1828 *
1829 * This should be the path for all ptrace stops.
1830 * We always set current->last_siginfo while stopped here.
1831 * That makes it a way to test a stopped process for
1832 * being ptrace-stopped vs being job-control-stopped.
1833 *
1834 * If we actually decide not to stop at all because the tracer
1835 * is gone, we keep current->exit_code unless clear_code.
1836 */
1837static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1838        __releases(&current->sighand->siglock)
1839        __acquires(&current->sighand->siglock)
1840{
1841        bool gstop_done = false;
1842
1843        if (arch_ptrace_stop_needed(exit_code, info)) {
1844                /*
1845                 * The arch code has something special to do before a
1846                 * ptrace stop.  This is allowed to block, e.g. for faults
1847                 * on user stack pages.  We can't keep the siglock while
1848                 * calling arch_ptrace_stop, so we must release it now.
1849                 * To preserve proper semantics, we must do this before
1850                 * any signal bookkeeping like checking group_stop_count.
1851                 * Meanwhile, a SIGKILL could come in before we retake the
1852                 * siglock.  That must prevent us from sleeping in TASK_TRACED.
1853                 * So after regaining the lock, we must check for SIGKILL.
1854                 */
1855                spin_unlock_irq(&current->sighand->siglock);
1856                arch_ptrace_stop(exit_code, info);
1857                spin_lock_irq(&current->sighand->siglock);
1858                if (sigkill_pending(current))
1859                        return;
1860        }
1861
1862        /*
1863         * We're committing to trapping.  TRACED should be visible before
1864         * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1865         * Also, transition to TRACED and updates to ->jobctl should be
1866         * atomic with respect to siglock and should be done after the arch
1867         * hook as siglock is released and regrabbed across it.
1868         */
1869        set_current_state(TASK_TRACED);
1870
1871        current->last_siginfo = info;
1872        current->exit_code = exit_code;
1873
1874        /*
1875         * If @why is CLD_STOPPED, we're trapping to participate in a group
1876         * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1877         * across siglock relocks since INTERRUPT was scheduled, PENDING
1878         * could be clear now.  We act as if SIGCONT is received after
1879         * TASK_TRACED is entered - ignore it.
1880         */
1881        if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1882                gstop_done = task_participate_group_stop(current);
1883
1884        /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1885        task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1886        if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
1887                task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1888
1889        /* entering a trap, clear TRAPPING */
1890        task_clear_jobctl_trapping(current);
1891
1892        spin_unlock_irq(&current->sighand->siglock);
1893        read_lock(&tasklist_lock);
1894        if (may_ptrace_stop()) {
1895                /*
1896                 * Notify parents of the stop.
1897                 *
1898                 * While ptraced, there are two parents - the ptracer and
1899                 * the real_parent of the group_leader.  The ptracer should
1900                 * know about every stop while the real parent is only
1901                 * interested in the completion of group stop.  The states
1902                 * for the two don't interact with each other.  Notify
1903                 * separately unless they're gonna be duplicates.
1904                 */
1905                do_notify_parent_cldstop(current, true, why);
1906                if (gstop_done && ptrace_reparented(current))
1907                        do_notify_parent_cldstop(current, false, why);
1908
1909                /*
1910                 * Don't want to allow preemption here, because
1911                 * sys_ptrace() needs this task to be inactive.
1912                 *
1913                 * XXX: implement read_unlock_no_resched().
1914                 */
1915                preempt_disable();
1916                read_unlock(&tasklist_lock);
1917                preempt_enable_no_resched();
1918                freezable_schedule();
1919        } else {
1920                /*
1921                 * By the time we got the lock, our tracer went away.
1922                 * Don't drop the lock yet, another tracer may come.
1923                 *
1924                 * If @gstop_done, the ptracer went away between group stop
1925                 * completion and here.  During detach, it would have set
1926                 * JOBCTL_STOP_PENDING on us and we'll re-enter
1927                 * TASK_STOPPED in do_signal_stop() on return, so notifying
1928                 * the real parent of the group stop completion is enough.
1929                 */
1930                if (gstop_done)
1931                        do_notify_parent_cldstop(current, false, why);
1932
1933                /* tasklist protects us from ptrace_freeze_traced() */
1934                __set_current_state(TASK_RUNNING);
1935                if (clear_code)
1936                        current->exit_code = 0;
1937                read_unlock(&tasklist_lock);
1938        }
1939
1940        /*
1941         * We are back.  Now reacquire the siglock before touching
1942         * last_siginfo, so that we are sure to have synchronized with
1943         * any signal-sending on another CPU that wants to examine it.
1944         */
1945        spin_lock_irq(&current->sighand->siglock);
1946        current->last_siginfo = NULL;
1947
1948        /* LISTENING can be set only during STOP traps, clear it */
1949        current->jobctl &= ~JOBCTL_LISTENING;
1950
1951        /*
1952         * Queued signals ignored us while we were stopped for tracing.
1953         * So check for any that we should take before resuming user mode.
1954         * This sets TIF_SIGPENDING, but never clears it.
1955         */
1956        recalc_sigpending_tsk(current);
1957}
1958
1959static void ptrace_do_notify(int signr, int exit_code, int why)
1960{
1961        siginfo_t info;
1962
1963        memset(&info, 0, sizeof info);
1964        info.si_signo = signr;
1965        info.si_code = exit_code;
1966        info.si_pid = task_pid_vnr(current);
1967        info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
1968
1969        /* Let the debugger run.  */
1970        ptrace_stop(exit_code, why, 1, &info);
1971}
1972
1973void ptrace_notify(int exit_code)
1974{
1975        BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1976        if (unlikely(current->task_works))
1977                task_work_run();
1978
1979        spin_lock_irq(&current->sighand->siglock);
1980        ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
1981        spin_unlock_irq(&current->sighand->siglock);
1982}
1983
1984/**
1985 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
1986 * @signr: signr causing group stop if initiating
1987 *
1988 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
1989 * and participate in it.  If already set, participate in the existing
1990 * group stop.  If participated in a group stop (and thus slept), %true is
1991 * returned with siglock released.
1992 *
1993 * If ptraced, this function doesn't handle stop itself.  Instead,
1994 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
1995 * untouched.  The caller must ensure that INTERRUPT trap handling takes
1996 * places afterwards.
1997 *
1998 * CONTEXT:
1999 * Must be called with @current->sighand->siglock held, which is released
2000 * on %true return.
2001 *
2002 * RETURNS:
2003 * %false if group stop is already cancelled or ptrace trap is scheduled.
2004 * %true if participated in group stop.
2005 */
2006static bool do_signal_stop(int signr)
2007        __releases(&current->sighand->siglock)
2008{
2009        struct signal_struct *sig = current->signal;
2010
2011        if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2012                unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2013                struct task_struct *t;
2014
2015                /* signr will be recorded in task->jobctl for retries */
2016                WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2017
2018                if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2019                    unlikely(signal_group_exit(sig)))
2020                        return false;
2021                /*
2022                 * There is no group stop already in progress.  We must
2023                 * initiate one now.
2024                 *
2025                 * While ptraced, a task may be resumed while group stop is
2026                 * still in effect and then receive a stop signal and
2027                 * initiate another group stop.  This deviates from the
2028                 * usual behavior as two consecutive stop signals can't
2029                 * cause two group stops when !ptraced.  That is why we
2030                 * also check !task_is_stopped(t) below.
2031                 *
2032                 * The condition can be distinguished by testing whether
2033                 * SIGNAL_STOP_STOPPED is already set.  Don't generate
2034                 * group_exit_code in such case.
2035                 *
2036                 * This is not necessary for SIGNAL_STOP_CONTINUED because
2037                 * an intervening stop signal is required to cause two
2038                 * continued events regardless of ptrace.
2039                 */
2040                if (!(sig->flags & SIGNAL_STOP_STOPPED))
2041                        sig->group_exit_code = signr;
2042
2043                sig->group_stop_count = 0;
2044
2045                if (task_set_jobctl_pending(current, signr | gstop))
2046                        sig->group_stop_count++;
2047
2048                for (t = next_thread(current); t != current;
2049                     t = next_thread(t)) {
2050                        /*
2051                         * Setting state to TASK_STOPPED for a group
2052                         * stop is always done with the siglock held,
2053                         * so this check has no races.
2054                         */
2055                        if (!task_is_stopped(t) &&
2056                            task_set_jobctl_pending(t, signr | gstop)) {
2057                                sig->group_stop_count++;
2058                                if (likely(!(t->ptrace & PT_SEIZED)))
2059                                        signal_wake_up(t, 0);
2060                                else
2061                                        ptrace_trap_notify(t);
2062                        }
2063                }
2064        }
2065
2066        if (likely(!current->ptrace)) {
2067                int notify = 0;
2068
2069                /*
2070                 * If there are no other threads in the group, or if there
2071                 * is a group stop in progress and we are the last to stop,
2072                 * report to the parent.
2073                 */
2074                if (task_participate_group_stop(current))
2075                        notify = CLD_STOPPED;
2076
2077                __set_current_state(TASK_STOPPED);
2078                spin_unlock_irq(&current->sighand->siglock);
2079
2080                /*
2081                 * Notify the parent of the group stop completion.  Because
2082                 * we're not holding either the siglock or tasklist_lock
2083                 * here, ptracer may attach inbetween; however, this is for
2084                 * group stop and should always be delivered to the real
2085                 * parent of the group leader.  The new ptracer will get
2086                 * its notification when this task transitions into
2087                 * TASK_TRACED.
2088                 */
2089                if (notify) {
2090                        read_lock(&tasklist_lock);
2091                        do_notify_parent_cldstop(current, false, notify);
2092                        read_unlock(&tasklist_lock);
2093                }
2094
2095                /* Now we don't run again until woken by SIGCONT or SIGKILL */
2096                freezable_schedule();
2097                return true;
2098        } else {
2099                /*
2100                 * While ptraced, group stop is handled by STOP trap.
2101                 * Schedule it and let the caller deal with it.
2102                 */
2103                task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2104                return false;
2105        }
2106}
2107
2108/**
2109 * do_jobctl_trap - take care of ptrace jobctl traps
2110 *
2111 * When PT_SEIZED, it's used for both group stop and explicit
2112 * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
2113 * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
2114 * the stop signal; otherwise, %SIGTRAP.
2115 *
2116 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2117 * number as exit_code and no siginfo.
2118 *
2119 * CONTEXT:
2120 * Must be called with @current->sighand->siglock held, which may be
2121 * released and re-acquired before returning with intervening sleep.
2122 */
2123static void do_jobctl_trap(void)
2124{
2125        struct signal_struct *signal = current->signal;
2126        int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2127
2128        if (current->ptrace & PT_SEIZED) {
2129                if (!signal->group_stop_count &&
2130                    !(signal->flags & SIGNAL_STOP_STOPPED))
2131                        signr = SIGTRAP;
2132                WARN_ON_ONCE(!signr);
2133                ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2134                                 CLD_STOPPED);
2135        } else {
2136                WARN_ON_ONCE(!signr);
2137                ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2138                current->exit_code = 0;
2139        }
2140}
2141
2142static int ptrace_signal(int signr, siginfo_t *info)
2143{
2144        ptrace_signal_deliver();
2145        /*
2146         * We do not check sig_kernel_stop(signr) but set this marker
2147         * unconditionally because we do not know whether debugger will
2148         * change signr. This flag has no meaning unless we are going
2149         * to stop after return from ptrace_stop(). In this case it will
2150         * be checked in do_signal_stop(), we should only stop if it was
2151         * not cleared by SIGCONT while we were sleeping. See also the
2152         * comment in dequeue_signal().
2153         */
2154        current->jobctl |= JOBCTL_STOP_DEQUEUED;
2155        ptrace_stop(signr, CLD_TRAPPED, 0, info);
2156
2157        /* We're back.  Did the debugger cancel the sig?  */
2158        signr = current->exit_code;
2159        if (signr == 0)
2160                return signr;
2161
2162        current->exit_code = 0;
2163
2164        /*
2165         * Update the siginfo structure if the signal has
2166         * changed.  If the debugger wanted something
2167         * specific in the siginfo structure then it should
2168         * have updated *info via PTRACE_SETSIGINFO.
2169         */
2170        if (signr != info->si_signo) {
2171                info->si_signo = signr;
2172                info->si_errno = 0;
2173                info->si_code = SI_USER;
2174                rcu_read_lock();
2175                info->si_pid = task_pid_vnr(current->parent);
2176                info->si_uid = from_kuid_munged(current_user_ns(),
2177                                                task_uid(current->parent));
2178                rcu_read_unlock();
2179        }
2180
2181        /* If the (new) signal is now blocked, requeue it.  */
2182        if (sigismember(&current->blocked, signr)) {
2183                specific_send_sig_info(signr, info, current);
2184                signr = 0;
2185        }
2186
2187        return signr;
2188}
2189
2190int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
2191                          struct pt_regs *regs, void *cookie)
2192{
2193        struct sighand_struct *sighand = current->sighand;
2194        struct signal_struct *signal = current->signal;
2195        int signr;
2196
2197        if (unlikely(current->task_works))
2198                task_work_run();
2199
2200        if (unlikely(uprobe_deny_signal()))
2201                return 0;
2202
2203        /*
2204         * Do this once, we can't return to user-mode if freezing() == T.
2205         * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2206         * thus do not need another check after return.
2207         */
2208        try_to_freeze();
2209
2210relock:
2211        spin_lock_irq(&sighand->siglock);
2212        /*
2213         * Every stopped thread goes here after wakeup. Check to see if
2214         * we should notify the parent, prepare_signal(SIGCONT) encodes
2215         * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2216         */
2217        if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2218                int why;
2219
2220                if (signal->flags & SIGNAL_CLD_CONTINUED)
2221                        why = CLD_CONTINUED;
2222                else
2223                        why = CLD_STOPPED;
2224
2225                signal->flags &= ~SIGNAL_CLD_MASK;
2226
2227                spin_unlock_irq(&sighand->siglock);
2228
2229                /*
2230                 * Notify the parent that we're continuing.  This event is
2231                 * always per-process and doesn't make whole lot of sense
2232                 * for ptracers, who shouldn't consume the state via
2233                 * wait(2) either, but, for backward compatibility, notify
2234                 * the ptracer of the group leader too unless it's gonna be
2235                 * a duplicate.
2236                 */
2237                read_lock(&tasklist_lock);
2238                do_notify_parent_cldstop(current, false, why);
2239
2240                if (ptrace_reparented(current->group_leader))
2241                        do_notify_parent_cldstop(current->group_leader,
2242                                                true, why);
2243                read_unlock(&tasklist_lock);
2244
2245                goto relock;
2246        }
2247
2248        for (;;) {
2249                struct k_sigaction *ka;
2250
2251                if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2252                    do_signal_stop(0))
2253                        goto relock;
2254
2255                if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2256                        do_jobctl_trap();
2257                        spin_unlock_irq(&sighand->siglock);
2258                        goto relock;
2259                }
2260
2261                signr = dequeue_signal(current, &current->blocked, info);
2262
2263                if (!signr)
2264                        break; /* will return 0 */
2265
2266                if (unlikely(current->ptrace) && signr != SIGKILL) {
2267                        signr = ptrace_signal(signr, info);
2268                        if (!signr)
2269                                continue;
2270                }
2271
2272                ka = &sighand->action[signr-1];
2273
2274                /* Trace actually delivered signals. */
2275                trace_signal_deliver(signr, info, ka);
2276
2277                if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
2278                        continue;
2279                if (ka->sa.sa_handler != SIG_DFL) {
2280                        /* Run the handler.  */
2281                        *return_ka = *ka;
2282
2283                        if (ka->sa.sa_flags & SA_ONESHOT)
2284                                ka->sa.sa_handler = SIG_DFL;
2285
2286                        break; /* will return non-zero "signr" value */
2287                }
2288
2289                /*
2290                 * Now we are doing the default action for this signal.
2291                 */
2292                if (sig_kernel_ignore(signr)) /* Default is nothing. */
2293                        continue;
2294
2295                /*
2296                 * Global init gets no signals it doesn't want.
2297                 * Container-init gets no signals it doesn't want from same
2298                 * container.
2299                 *
2300                 * Note that if global/container-init sees a sig_kernel_only()
2301                 * signal here, the signal must have been generated internally
2302                 * or must have come from an ancestor namespace. In either
2303                 * case, the signal cannot be dropped.
2304                 */
2305                if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2306                                !sig_kernel_only(signr))
2307                        continue;
2308
2309                if (sig_kernel_stop(signr)) {
2310                        /*
2311                         * The default action is to stop all threads in
2312                         * the thread group.  The job control signals
2313                         * do nothing in an orphaned pgrp, but SIGSTOP
2314                         * always works.  Note that siglock needs to be
2315                         * dropped during the call to is_orphaned_pgrp()
2316                         * because of lock ordering with tasklist_lock.
2317                         * This allows an intervening SIGCONT to be posted.
2318                         * We need to check for that and bail out if necessary.
2319                         */
2320                        if (signr != SIGSTOP) {
2321                                spin_unlock_irq(&sighand->siglock);
2322
2323                                /* signals can be posted during this window */
2324
2325                                if (is_current_pgrp_orphaned())
2326                                        goto relock;
2327
2328                                spin_lock_irq(&sighand->siglock);
2329                        }
2330
2331                        if (likely(do_signal_stop(info->si_signo))) {
2332                                /* It released the siglock.  */
2333                                goto relock;
2334                        }
2335
2336                        /*
2337                         * We didn't actually stop, due to a race
2338                         * with SIGCONT or something like that.
2339                         */
2340                        continue;
2341                }
2342
2343                spin_unlock_irq(&sighand->siglock);
2344
2345                /*
2346                 * Anything else is fatal, maybe with a core dump.
2347                 */
2348                current->flags |= PF_SIGNALED;
2349
2350                if (sig_kernel_coredump(signr)) {
2351                        if (print_fatal_signals)
2352                                print_fatal_signal(info->si_signo);
2353                        /*
2354                         * If it was able to dump core, this kills all
2355                         * other threads in the group and synchronizes with
2356                         * their demise.  If we lost the race with another
2357                         * thread getting here, it set group_exit_code
2358                         * first and our do_group_exit call below will use
2359                         * that value and ignore the one we pass it.
2360                         */
2361                        do_coredump(info);
2362                }
2363
2364                /*
2365                 * Death signals, no core dump.
2366                 */
2367                do_group_exit(info->si_signo);
2368                /* NOTREACHED */
2369        }
2370        spin_unlock_irq(&sighand->siglock);
2371        return signr;
2372}
2373
2374/**
2375 * signal_delivered - 
2376 * @sig:                number of signal being delivered
2377 * @info:               siginfo_t of signal being delivered
2378 * @ka:                 sigaction setting that chose the handler
2379 * @regs:               user register state
2380 * @stepping:           nonzero if debugger single-step or block-step in use
2381 *
2382 * This function should be called when a signal has succesfully been
2383 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
2384 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2385 * is set in @ka->sa.sa_flags.  Tracing is notified.
2386 */
2387void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
2388                        struct pt_regs *regs, int stepping)
2389{
2390        sigset_t blocked;
2391
2392        /* A signal was successfully delivered, and the
2393           saved sigmask was stored on the signal frame,
2394           and will be restored by sigreturn.  So we can
2395           simply clear the restore sigmask flag.  */
2396        clear_restore_sigmask();
2397
2398        sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
2399        if (!(ka->sa.sa_flags & SA_NODEFER))
2400                sigaddset(&blocked, sig);
2401        set_current_blocked(&blocked);
2402        tracehook_signal_handler(sig, info, ka, regs, stepping);
2403}
2404
2405void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2406{
2407        if (failed)
2408                force_sigsegv(ksig->sig, current);
2409        else
2410                signal_delivered(ksig->sig, &ksig->info, &ksig->ka,
2411                        signal_pt_regs(), stepping);
2412}
2413
2414/*
2415 * It could be that complete_signal() picked us to notify about the
2416 * group-wide signal. Other threads should be notified now to take
2417 * the shared signals in @which since we will not.
2418 */
2419static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2420{
2421        sigset_t retarget;
2422        struct task_struct *t;
2423
2424        sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2425        if (sigisemptyset(&retarget))
2426                return;
2427
2428        t = tsk;
2429        while_each_thread(tsk, t) {
2430                if (t->flags & PF_EXITING)
2431                        continue;
2432
2433                if (!has_pending_signals(&retarget, &t->blocked))
2434                        continue;
2435                /* Remove the signals this thread can handle. */
2436                sigandsets(&retarget, &retarget, &t->blocked);
2437
2438                if (!signal_pending(t))
2439                        signal_wake_up(t, 0);
2440
2441                if (sigisemptyset(&retarget))
2442                        break;
2443        }
2444}
2445
2446void exit_signals(struct task_struct *tsk)
2447{
2448        int group_stop = 0;
2449        sigset_t unblocked;
2450
2451        /*
2452         * @tsk is about to have PF_EXITING set - lock out users which
2453         * expect stable threadgroup.
2454         */
2455        threadgroup_change_begin(tsk);
2456
2457        if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
2458                tsk->flags |= PF_EXITING;
2459                threadgroup_change_end(tsk);
2460                return;
2461        }
2462
2463        spin_lock_irq(&tsk->sighand->siglock);
2464        /*
2465         * From now this task is not visible for group-wide signals,
2466         * see wants_signal(), do_signal_stop().
2467         */
2468        tsk->flags |= PF_EXITING;
2469
2470        threadgroup_change_end(tsk);
2471
2472        if (!signal_pending(tsk))
2473                goto out;
2474
2475        unblocked = tsk->blocked;
2476        signotset(&unblocked);
2477        retarget_shared_pending(tsk, &unblocked);
2478
2479        if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2480            task_participate_group_stop(tsk))
2481                group_stop = CLD_STOPPED;
2482out:
2483        spin_unlock_irq(&tsk->sighand->siglock);
2484
2485        /*
2486         * If group stop has completed, deliver the notification.  This
2487         * should always go to the real parent of the group leader.
2488         */
2489        if (unlikely(group_stop)) {
2490                read_lock(&tasklist_lock);
2491                do_notify_parent_cldstop(tsk, false, group_stop);
2492                read_unlock(&tasklist_lock);
2493        }
2494}
2495
2496EXPORT_SYMBOL(recalc_sigpending);
2497EXPORT_SYMBOL_GPL(dequeue_signal);
2498EXPORT_SYMBOL(flush_signals);
2499EXPORT_SYMBOL(force_sig);
2500EXPORT_SYMBOL(send_sig);
2501EXPORT_SYMBOL(send_sig_info);
2502EXPORT_SYMBOL(sigprocmask);
2503EXPORT_SYMBOL(block_all_signals);
2504EXPORT_SYMBOL(unblock_all_signals);
2505
2506
2507/*
2508 * System call entry points.
2509 */
2510
2511/**
2512 *  sys_restart_syscall - restart a system call
2513 */
2514SYSCALL_DEFINE0(restart_syscall)
2515{
2516        struct restart_block *restart = &current_thread_info()->restart_block;
2517        return restart->fn(restart);
2518}
2519
2520long do_no_restart_syscall(struct restart_block *param)
2521{
2522        return -EINTR;
2523}
2524
2525static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2526{
2527        if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2528                sigset_t newblocked;
2529                /* A set of now blocked but previously unblocked signals. */
2530                sigandnsets(&newblocked, newset, &current->blocked);
2531                retarget_shared_pending(tsk, &newblocked);
2532        }
2533        tsk->blocked = *newset;
2534        recalc_sigpending();
2535}
2536
2537/**
2538 * set_current_blocked - change current->blocked mask
2539 * @newset: new mask
2540 *
2541 * It is wrong to change ->blocked directly, this helper should be used
2542 * to ensure the process can't miss a shared signal we are going to block.
2543 */
2544void set_current_blocked(sigset_t *newset)
2545{
2546        sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2547        __set_current_blocked(newset);
2548}
2549
2550void __set_current_blocked(const sigset_t *newset)
2551{
2552        struct task_struct *tsk = current;
2553
2554        spin_lock_irq(&tsk->sighand->siglock);
2555        __set_task_blocked(tsk, newset);
2556        spin_unlock_irq(&tsk->sighand->siglock);
2557}
2558
2559/*
2560 * This is also useful for kernel threads that want to temporarily
2561 * (or permanently) block certain signals.
2562 *
2563 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2564 * interface happily blocks "unblockable" signals like SIGKILL
2565 * and friends.
2566 */
2567int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2568{
2569        struct task_struct *tsk = current;
2570        sigset_t newset;
2571
2572        /* Lockless, only current can change ->blocked, never from irq */
2573        if (oldset)
2574                *oldset = tsk->blocked;
2575
2576        switch (how) {
2577        case SIG_BLOCK:
2578                sigorsets(&newset, &tsk->blocked, set);
2579                break;
2580        case SIG_UNBLOCK:
2581                sigandnsets(&newset, &tsk->blocked, set);
2582                break;
2583        case SIG_SETMASK:
2584                newset = *set;
2585                break;
2586        default:
2587                return -EINVAL;
2588        }
2589
2590        __set_current_blocked(&newset);
2591        return 0;
2592}
2593
2594/**
2595 *  sys_rt_sigprocmask - change the list of currently blocked signals
2596 *  @how: whether to add, remove, or set signals
2597 *  @nset: stores pending signals
2598 *  @oset: previous value of signal mask if non-null
2599 *  @sigsetsize: size of sigset_t type
2600 */
2601SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2602                sigset_t __user *, oset, size_t, sigsetsize)
2603{
2604        sigset_t old_set, new_set;
2605        int error;
2606
2607        /* XXX: Don't preclude handling different sized sigset_t's.  */
2608        if (sigsetsize != sizeof(sigset_t))
2609                return -EINVAL;
2610
2611        old_set = current->blocked;
2612
2613        if (nset) {
2614                if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2615                        return -EFAULT;
2616                sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2617
2618                error = sigprocmask(how, &new_set, NULL);
2619                if (error)
2620                        return error;
2621        }
2622
2623        if (oset) {
2624                if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2625                        return -EFAULT;
2626        }
2627
2628        return 0;
2629}
2630
2631#ifdef CONFIG_COMPAT
2632COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2633                compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2634{
2635#ifdef __BIG_ENDIAN
2636        sigset_t old_set = current->blocked;
2637
2638        /* XXX: Don't preclude handling different sized sigset_t's.  */
2639        if (sigsetsize != sizeof(sigset_t))
2640                return -EINVAL;
2641
2642        if (nset) {
2643                compat_sigset_t new32;
2644                sigset_t new_set;
2645                int error;
2646                if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
2647                        return -EFAULT;
2648
2649                sigset_from_compat(&new_set, &new32);
2650                sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2651
2652                error = sigprocmask(how, &new_set, NULL);
2653                if (error)
2654                        return error;
2655        }
2656        if (oset) {
2657                compat_sigset_t old32;
2658                sigset_to_compat(&old32, &old_set);
2659                if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
2660                        return -EFAULT;
2661        }
2662        return 0;
2663#else
2664        return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
2665                                  (sigset_t __user *)oset, sigsetsize);
2666#endif
2667}
2668#endif
2669
2670static int do_sigpending(void *set, unsigned long sigsetsize)
2671{
2672        if (sigsetsize > sizeof(sigset_t))
2673                return -EINVAL;
2674
2675        spin_lock_irq(&current->sighand->siglock);
2676        sigorsets(set, &current->pending.signal,
2677                  &current->signal->shared_pending.signal);
2678        spin_unlock_irq(&current->sighand->siglock);
2679
2680        /* Outside the lock because only this thread touches it.  */
2681        sigandsets(set, &current->blocked, set);
2682        return 0;
2683}
2684
2685/**
2686 *  sys_rt_sigpending - examine a pending signal that has been raised
2687 *                      while blocked
2688 *  @uset: stores pending signals
2689 *  @sigsetsize: size of sigset_t type or larger
2690 */
2691SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2692{
2693        sigset_t set;
2694        int err = do_sigpending(&set, sigsetsize);
2695        if (!err && copy_to_user(uset, &set, sigsetsize))
2696                err = -EFAULT;
2697        return err;
2698}
2699
2700#ifdef CONFIG_COMPAT
2701COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2702                compat_size_t, sigsetsize)
2703{
2704#ifdef __BIG_ENDIAN
2705        sigset_t set;
2706        int err = do_sigpending(&set, sigsetsize);
2707        if (!err) {
2708                compat_sigset_t set32;
2709                sigset_to_compat(&set32, &set);
2710                /* we can get here only if sigsetsize <= sizeof(set) */
2711                if (copy_to_user(uset, &set32, sigsetsize))
2712                        err = -EFAULT;
2713        }
2714        return err;
2715#else
2716        return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
2717#endif
2718}
2719#endif
2720
2721#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2722
2723int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2724{
2725        int err;
2726
2727        if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2728                return -EFAULT;
2729        if (from->si_code < 0)
2730                return __copy_to_user(to, from, sizeof(siginfo_t))
2731                        ? -EFAULT : 0;
2732        /*
2733         * If you change siginfo_t structure, please be sure
2734         * this code is fixed accordingly.
2735         * Please remember to update the signalfd_copyinfo() function
2736         * inside fs/signalfd.c too, in case siginfo_t changes.
2737         * It should never copy any pad contained in the structure
2738         * to avoid security leaks, but must copy the generic
2739         * 3 ints plus the relevant union member.
2740         */
2741        err = __put_user(from->si_signo, &to->si_signo);
2742        err |= __put_user(from->si_errno, &to->si_errno);
2743        err |= __put_user((short)from->si_code, &to->si_code);
2744        switch (from->si_code & __SI_MASK) {
2745        case __SI_KILL:
2746                err |= __put_user(from->si_pid, &to->si_pid);
2747                err |= __put_user(from->si_uid, &to->si_uid);
2748                break;
2749        case __SI_TIMER:
2750                 err |= __put_user(from->si_tid, &to->si_tid);
2751                 err |= __put_user(from->si_overrun, &to->si_overrun);
2752                 err |= __put_user(from->si_ptr, &to->si_ptr);
2753                break;
2754        case __SI_POLL:
2755                err |= __put_user(from->si_band, &to->si_band);
2756                err |= __put_user(from->si_fd, &to->si_fd);
2757                break;
2758        case __SI_FAULT:
2759                err |= __put_user(from->si_addr, &to->si_addr);
2760#ifdef __ARCH_SI_TRAPNO
2761                err |= __put_user(from->si_trapno, &to->si_trapno);
2762#endif
2763#ifdef BUS_MCEERR_AO
2764                /*
2765                 * Other callers might not initialize the si_lsb field,
2766                 * so check explicitly for the right codes here.
2767                 */
2768                if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
2769                        err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2770#endif
2771                break;
2772        case __SI_CHLD:
2773                err |= __put_user(from->si_pid, &to->si_pid);
2774                err |= __put_user(from->si_uid, &to->si_uid);
2775                err |= __put_user(from->si_status, &to->si_status);
2776                err |= __put_user(from->si_utime, &to->si_utime);
2777                err |= __put_user(from->si_stime, &to->si_stime);
2778                break;
2779        case __SI_RT: /* This is not generated by the kernel as of now. */
2780        case __SI_MESGQ: /* But this is */
2781                err |= __put_user(from->si_pid, &to->si_pid);
2782                err |= __put_user(from->si_uid, &to->si_uid);
2783                err |= __put_user(from->si_ptr, &to->si_ptr);
2784                break;
2785#ifdef __ARCH_SIGSYS
2786        case __SI_SYS:
2787                err |= __put_user(from->si_call_addr, &to->si_call_addr);
2788                err |= __put_user(from->si_syscall, &to->si_syscall);
2789                err |= __put_user(from->si_arch, &to->si_arch);
2790                break;
2791#endif
2792        default: /* this is just in case for now ... */
2793                err |= __put_user(from->si_pid, &to->si_pid);
2794                err |= __put_user(from->si_uid, &to->si_uid);
2795                break;
2796        }
2797        return err;
2798}
2799
2800#endif
2801
2802/**
2803 *  do_sigtimedwait - wait for queued signals specified in @which
2804 *  @which: queued signals to wait for
2805 *  @info: if non-null, the signal's siginfo is returned here
2806 *  @ts: upper bound on process time suspension
2807 */
2808int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2809                        const struct timespec *ts)
2810{
2811        struct task_struct *tsk = current;
2812        long timeout = MAX_SCHEDULE_TIMEOUT;
2813        sigset_t mask = *which;
2814        int sig;
2815
2816        if (ts) {
2817                if (!timespec_valid(ts))
2818                        return -EINVAL;
2819                timeout = timespec_to_jiffies(ts);
2820                /*
2821                 * We can be close to the next tick, add another one
2822                 * to ensure we will wait at least the time asked for.
2823                 */
2824                if (ts->tv_sec || ts->tv_nsec)
2825                        timeout++;
2826        }
2827
2828        /*
2829         * Invert the set of allowed signals to get those we want to block.
2830         */
2831        sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
2832        signotset(&mask);
2833
2834        spin_lock_irq(&tsk->sighand->siglock);
2835        sig = dequeue_signal(tsk, &mask, info);
2836        if (!sig && timeout) {
2837                /*
2838                 * None ready, temporarily unblock those we're interested
2839                 * while we are sleeping in so that we'll be awakened when
2840                 * they arrive. Unblocking is always fine, we can avoid
2841                 * set_current_blocked().
2842                 */
2843                tsk->real_blocked = tsk->blocked;
2844                sigandsets(&tsk->blocked, &tsk->blocked, &mask);
2845                recalc_sigpending();
2846                spin_unlock_irq(&tsk->sighand->siglock);
2847
2848                timeout = schedule_timeout_interruptible(timeout);
2849
2850                spin_lock_irq(&tsk->sighand->siglock);
2851                __set_task_blocked(tsk, &tsk->real_blocked);
2852                siginitset(&tsk->real_blocked, 0);
2853                sig = dequeue_signal(tsk, &mask, info);
2854        }
2855        spin_unlock_irq(&tsk->sighand->siglock);
2856
2857        if (sig)
2858                return sig;
2859        return timeout ? -EINTR : -EAGAIN;
2860}
2861
2862/**
2863 *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
2864 *                      in @uthese
2865 *  @uthese: queued signals to wait for
2866 *  @uinfo: if non-null, the signal's siginfo is returned here
2867 *  @uts: upper bound on process time suspension
2868 *  @sigsetsize: size of sigset_t type
2869 */
2870SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
2871                siginfo_t __user *, uinfo, const struct timespec __user *, uts,
2872                size_t, sigsetsize)
2873{
2874        sigset_t these;
2875        struct timespec ts;
2876        siginfo_t info;
2877        int ret;
2878
2879        /* XXX: Don't preclude handling different sized sigset_t's.  */
2880        if (sigsetsize != sizeof(sigset_t))
2881                return -EINVAL;
2882
2883        if (copy_from_user(&these, uthese, sizeof(these)))
2884                return -EFAULT;
2885
2886        if (uts) {
2887                if (copy_from_user(&ts, uts, sizeof(ts)))
2888                        return -EFAULT;
2889        }
2890
2891        ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
2892
2893        if (ret > 0 && uinfo) {
2894                if (copy_siginfo_to_user(uinfo, &info))
2895                        ret = -EFAULT;
2896        }
2897
2898        return ret;
2899}
2900
2901/**
2902 *  sys_kill - send a signal to a process
2903 *  @pid: the PID of the process
2904 *  @sig: signal to be sent
2905 */
2906SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
2907{
2908        struct siginfo info;
2909
2910        info.si_signo = sig;
2911        info.si_errno = 0;
2912        info.si_code = SI_USER;
2913        info.si_pid = task_tgid_vnr(current);
2914        info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2915
2916        return kill_something_info(sig, &info, pid);
2917}
2918
2919static int
2920do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
2921{
2922        struct task_struct *p;
2923        int error = -ESRCH;
2924
2925        rcu_read_lock();
2926        p = find_task_by_vpid(pid);
2927        if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2928                error = check_kill_permission(sig, info, p);
2929                /*
2930                 * The null signal is a permissions and process existence
2931                 * probe.  No signal is actually delivered.
2932                 */
2933                if (!error && sig) {
2934                        error = do_send_sig_info(sig, info, p, false);
2935                        /*
2936                         * If lock_task_sighand() failed we pretend the task
2937                         * dies after receiving the signal. The window is tiny,
2938                         * and the signal is private anyway.
2939                         */
2940                        if (unlikely(error == -ESRCH))
2941                                error = 0;
2942                }
2943        }
2944        rcu_read_unlock();
2945
2946        return error;
2947}
2948
2949static int do_tkill(pid_t tgid, pid_t pid, int sig)
2950{
2951        struct siginfo info = {};
2952
2953        info.si_signo = sig;
2954        info.si_errno = 0;
2955        info.si_code = SI_TKILL;
2956        info.si_pid = task_tgid_vnr(current);
2957        info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2958
2959        return do_send_specific(tgid, pid, sig, &info);
2960}
2961
2962/**
2963 *  sys_tgkill - send signal to one specific thread
2964 *  @tgid: the thread group ID of the thread
2965 *  @pid: the PID of the thread
2966 *  @sig: signal to be sent
2967 *
2968 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
2969 *  exists but it's not belonging to the target process anymore. This
2970 *  method solves the problem of threads exiting and PIDs getting reused.
2971 */
2972SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2973{
2974        /* This is only valid for single tasks */
2975        if (pid <= 0 || tgid <= 0)
2976                return -EINVAL;
2977
2978        return do_tkill(tgid, pid, sig);
2979}
2980
2981/**
2982 *  sys_tkill - send signal to one specific task
2983 *  @pid: the PID of the task
2984 *  @sig: signal to be sent
2985 *
2986 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
2987 */
2988SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
2989{
2990        /* This is only valid for single tasks */
2991        if (pid <= 0)
2992                return -EINVAL;
2993
2994        return do_tkill(0, pid, sig);
2995}
2996
2997static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
2998{
2999        /* Not even root can pretend to send signals from the kernel.
3000         * Nor can they impersonate a kill()/tgkill(), which adds source info.
3001         */
3002        if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3003            (task_pid_vnr(current) != pid)) {
3004                /* We used to allow any < 0 si_code */
3005                WARN_ON_ONCE(info->si_code < 0);
3006                return -EPERM;
3007        }
3008        info->si_signo = sig;
3009
3010        /* POSIX.1b doesn't mention process groups.  */
3011        return kill_proc_info(sig, info, pid);
3012}
3013
3014/**
3015 *  sys_rt_sigqueueinfo - send signal information to a signal
3016 *  @pid: the PID of the thread
3017 *  @sig: signal to be sent
3018 *  @uinfo: signal info to be sent
3019 */
3020SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3021                siginfo_t __user *, uinfo)
3022{
3023        siginfo_t info;
3024        if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3025                return -EFAULT;
3026        return do_rt_sigqueueinfo(pid, sig, &info);
3027}
3028
3029#ifdef CONFIG_COMPAT
3030COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3031                        compat_pid_t, pid,
3032                        int, sig,
3033                        struct compat_siginfo __user *, uinfo)
3034{
3035        siginfo_t info;
3036        int ret = copy_siginfo_from_user32(&info, uinfo);
3037        if (unlikely(ret))
3038                return ret;
3039        return do_rt_sigqueueinfo(pid, sig, &info);
3040}
3041#endif
3042
3043static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3044{
3045        /* This is only valid for single tasks */
3046        if (pid <= 0 || tgid <= 0)
3047                return -EINVAL;
3048
3049        /* Not even root can pretend to send signals from the kernel.
3050         * Nor can they impersonate a kill()/tgkill(), which adds source info.
3051         */
3052        if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
3053            (task_pid_vnr(current) != pid)) {
3054                /* We used to allow any < 0 si_code */
3055                WARN_ON_ONCE(info->si_code < 0);
3056                return -EPERM;
3057        }
3058        info->si_signo = sig;
3059
3060        return do_send_specific(tgid, pid, sig, info);
3061}
3062
3063SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3064                siginfo_t __user *, uinfo)
3065{
3066        siginfo_t info;
3067
3068        if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3069                return -EFAULT;
3070
3071        return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3072}
3073
3074#ifdef CONFIG_COMPAT
3075COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3076                        compat_pid_t, tgid,
3077                        compat_pid_t, pid,
3078                        int, sig,
3079                        struct compat_siginfo __user *, uinfo)
3080{
3081        siginfo_t info;
3082
3083        if (copy_siginfo_from_user32(&info, uinfo))
3084                return -EFAULT;
3085        return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3086}
3087#endif
3088
3089int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3090{
3091        struct task_struct *t = current;
3092        struct k_sigaction *k;
3093        sigset_t mask;
3094
3095        if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3096                return -EINVAL;
3097
3098        k = &t->sighand->action[sig-1];
3099
3100        spin_lock_irq(&current->sighand->siglock);
3101        if (oact)
3102                *oact = *k;
3103
3104        if (act) {
3105                sigdelsetmask(&act->sa.sa_mask,
3106                              sigmask(SIGKILL) | sigmask(SIGSTOP));
3107                *k = *act;
3108                /*
3109                 * POSIX 3.3.1.3:
3110                 *  "Setting a signal action to SIG_IGN for a signal that is
3111                 *   pending shall cause the pending signal to be discarded,
3112                 *   whether or not it is blocked."
3113                 *
3114                 *  "Setting a signal action to SIG_DFL for a signal that is
3115                 *   pending and whose default action is to ignore the signal
3116                 *   (for example, SIGCHLD), shall cause the pending signal to
3117                 *   be discarded, whether or not it is blocked"
3118                 */
3119                if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3120                        sigemptyset(&mask);
3121                        sigaddset(&mask, sig);
3122                        rm_from_queue_full(&mask, &t->signal->shared_pending);
3123                        do {
3124                                rm_from_queue_full(&mask, &t->pending);
3125                                t = next_thread(t);
3126                        } while (t != current);
3127                }
3128        }
3129
3130        spin_unlock_irq(&current->sighand->siglock);
3131        return 0;
3132}
3133
3134static int 
3135do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
3136{
3137        stack_t oss;
3138        int error;
3139
3140        oss.ss_sp = (void __user *) current->sas_ss_sp;
3141        oss.ss_size = current->sas_ss_size;
3142        oss.ss_flags = sas_ss_flags(sp);
3143
3144        if (uss) {
3145                void __user *ss_sp;
3146                size_t ss_size;
3147                int ss_flags;
3148
3149                error = -EFAULT;
3150                if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
3151                        goto out;
3152                error = __get_user(ss_sp, &uss->ss_sp) |
3153                        __get_user(ss_flags, &uss->ss_flags) |
3154                        __get_user(ss_size, &uss->ss_size);
3155                if (error)
3156                        goto out;
3157
3158                error = -EPERM;
3159                if (on_sig_stack(sp))
3160                        goto out;
3161
3162                error = -EINVAL;
3163                /*
3164                 * Note - this code used to test ss_flags incorrectly:
3165                 *        old code may have been written using ss_flags==0
3166                 *        to mean ss_flags==SS_ONSTACK (as this was the only
3167                 *        way that worked) - this fix preserves that older
3168                 *        mechanism.
3169                 */
3170                if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
3171                        goto out;
3172
3173                if (ss_flags == SS_DISABLE) {
3174                        ss_size = 0;
3175                        ss_sp = NULL;
3176                } else {
3177                        error = -ENOMEM;
3178                        if (ss_size < MINSIGSTKSZ)
3179                                goto out;
3180                }
3181
3182                current->sas_ss_sp = (unsigned long) ss_sp;
3183                current->sas_ss_size = ss_size;
3184        }
3185
3186        error = 0;
3187        if (uoss) {
3188                error = -EFAULT;
3189                if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
3190                        goto out;
3191                error = __put_user(oss.ss_sp, &uoss->ss_sp) |
3192                        __put_user(oss.ss_size, &uoss->ss_size) |
3193                        __put_user(oss.ss_flags, &uoss->ss_flags);
3194        }
3195
3196out:
3197        return error;
3198}
3199SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3200{
3201        return do_sigaltstack(uss, uoss, current_user_stack_pointer());
3202}
3203
3204int restore_altstack(const stack_t __user *uss)
3205{
3206        int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
3207        /* squash all but EFAULT for now */
3208        return err == -EFAULT ? err : 0;
3209}
3210
3211int __save_altstack(stack_t __user *uss, unsigned long sp)
3212{
3213        struct task_struct *t = current;
3214        return  __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3215                __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3216                __put_user(t->sas_ss_size, &uss->ss_size);
3217}
3218
3219#ifdef CONFIG_COMPAT
3220COMPAT_SYSCALL_DEFINE2(sigaltstack,
3221                        const compat_stack_t __user *, uss_ptr,
3222                        compat_stack_t __user *, uoss_ptr)
3223{
3224        stack_t uss, uoss;
3225        int ret;
3226        mm_segment_t seg;
3227
3228        if (uss_ptr) {
3229                compat_stack_t uss32;
3230
3231                memset(&uss, 0, sizeof(stack_t));
3232                if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3233                        return -EFAULT;
3234                uss.ss_sp = compat_ptr(uss32.ss_sp);
3235                uss.ss_flags = uss32.ss_flags;
3236                uss.ss_size = uss32.ss_size;
3237        }
3238        seg = get_fs();
3239        set_fs(KERNEL_DS);
3240        ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
3241                             (stack_t __force __user *) &uoss,
3242                             compat_user_stack_pointer());
3243        set_fs(seg);
3244        if (ret >= 0 && uoss_ptr)  {
3245                if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
3246                    __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
3247                    __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
3248                    __put_user(uoss.ss_size, &uoss_ptr->ss_size))
3249                        ret = -EFAULT;
3250        }
3251        return ret;
3252}
3253
3254int compat_restore_altstack(const compat_stack_t __user *uss)
3255{
3256        int err = compat_sys_sigaltstack(uss, NULL);
3257        /* squash all but -EFAULT for now */
3258        return err == -EFAULT ? err : 0;
3259}
3260
3261int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3262{
3263        struct task_struct *t = current;
3264        return  __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
3265                __put_user(sas_ss_flags(sp), &uss->ss_flags) |
3266                __put_user(t->sas_ss_size, &uss->ss_size);
3267}
3268#endif
3269
3270#ifdef __ARCH_WANT_SYS_SIGPENDING
3271
3272/**
3273 *  sys_sigpending - examine pending signals
3274 *  @set: where mask of pending signal is returned
3275 */
3276SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
3277{
3278        return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 
3279}
3280
3281#endif
3282
3283#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3284/**
3285 *  sys_sigprocmask - examine and change blocked signals
3286 *  @how: whether to add, remove, or set signals
3287 *  @nset: signals to add or remove (if non-null)
3288 *  @oset: previous value of signal mask if non-null
3289 *
3290 * Some platforms have their own version with special arguments;
3291 * others support only sys_rt_sigprocmask.
3292 */
3293
3294SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3295                old_sigset_t __user *, oset)
3296{
3297        old_sigset_t old_set, new_set;
3298        sigset_t new_blocked;
3299
3300        old_set = current->blocked.sig[0];
3301
3302        if (nset) {
3303                if (copy_from_user(&new_set, nset, sizeof(*nset)))
3304                        return -EFAULT;
3305
3306                new_blocked = current->blocked;
3307
3308                switch (how) {
3309                case SIG_BLOCK:
3310                        sigaddsetmask(&new_blocked, new_set);
3311                        break;
3312                case SIG_UNBLOCK:
3313                        sigdelsetmask(&new_blocked, new_set);
3314                        break;
3315                case SIG_SETMASK:
3316                        new_blocked.sig[0] = new_set;
3317                        break;
3318                default:
3319                        return -EINVAL;
3320                }
3321
3322                set_current_blocked(&new_blocked);
3323        }
3324
3325        if (oset) {
3326                if (copy_to_user(oset, &old_set, sizeof(*oset)))
3327                        return -EFAULT;
3328        }
3329
3330        return 0;
3331}
3332#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3333
3334#ifndef CONFIG_ODD_RT_SIGACTION
3335/**
3336 *  sys_rt_sigaction - alter an action taken by a process
3337 *  @sig: signal to be sent
3338 *  @act: new sigaction
3339 *  @oact: used to save the previous sigaction
3340 *  @sigsetsize: size of sigset_t type
3341 */
3342SYSCALL_DEFINE4(rt_sigaction, int, sig,
3343                const struct sigaction __user *, act,
3344                struct sigaction __user *, oact,
3345                size_t, sigsetsize)
3346{
3347        struct k_sigaction new_sa, old_sa;
3348        int ret = -EINVAL;
3349
3350        /* XXX: Don't preclude handling different sized sigset_t's.  */
3351        if (sigsetsize != sizeof(sigset_t))
3352                goto out;
3353
3354        if (act) {
3355                if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3356                        return -EFAULT;
3357        }
3358
3359        ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
3360
3361        if (!ret && oact) {
3362                if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3363                        return -EFAULT;
3364        }
3365out:
3366        return ret;
3367}
3368#ifdef CONFIG_COMPAT
3369COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3370                const struct compat_sigaction __user *, act,
3371                struct compat_sigaction __user *, oact,
3372                compat_size_t, sigsetsize)
3373{
3374        struct k_sigaction new_ka, old_ka;
3375        compat_sigset_t mask;
3376#ifdef __ARCH_HAS_SA_RESTORER
3377        compat_uptr_t restorer;
3378#endif
3379        int ret;
3380
3381        /* XXX: Don't preclude handling different sized sigset_t's.  */
3382        if (sigsetsize != sizeof(compat_sigset_t))
3383                return -EINVAL;
3384
3385        if (act) {
3386                compat_uptr_t handler;
3387                ret = get_user(handler, &act->sa_handler);
3388                new_ka.sa.sa_handler = compat_ptr(handler);
3389#ifdef __ARCH_HAS_SA_RESTORER
3390                ret |= get_user(restorer, &act->sa_restorer);
3391                new_ka.sa.sa_restorer = compat_ptr(restorer);
3392#endif
3393                ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3394                ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
3395                if (ret)
3396                        return -EFAULT;
3397                sigset_from_compat(&new_ka.sa.sa_mask, &mask);
3398        }
3399
3400        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3401        if (!ret && oact) {
3402                sigset_to_compat(&mask, &old_ka.sa.sa_mask);
3403                ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
3404                               &oact->sa_handler);
3405                ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3406                ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3407#ifdef __ARCH_HAS_SA_RESTORER
3408                ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3409                                &oact->sa_restorer);
3410#endif
3411        }
3412        return ret;
3413}
3414#endif
3415#endif /* !CONFIG_ODD_RT_SIGACTION */
3416
3417#ifdef CONFIG_OLD_SIGACTION
3418SYSCALL_DEFINE3(sigaction, int, sig,
3419                const struct old_sigaction __user *, act,
3420                struct old_sigaction __user *, oact)
3421{
3422        struct k_sigaction new_ka, old_ka;
3423        int ret;
3424
3425        if (act) {
3426                old_sigset_t mask;
3427                if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3428                    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3429                    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3430                    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3431                    __get_user(mask, &act->sa_mask))
3432                        return -EFAULT;
3433#ifdef __ARCH_HAS_KA_RESTORER
3434                new_ka.ka_restorer = NULL;
3435#endif
3436                siginitset(&new_ka.sa.sa_mask, mask);
3437        }
3438
3439        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3440
3441        if (!ret && oact) {
3442                if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3443                    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3444                    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3445                    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3446                    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3447                        return -EFAULT;
3448        }
3449
3450        return ret;
3451}
3452#endif
3453#ifdef CONFIG_COMPAT_OLD_SIGACTION
3454COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3455                const struct compat_old_sigaction __user *, act,
3456                struct compat_old_sigaction __user *, oact)
3457{
3458        struct k_sigaction new_ka, old_ka;
3459        int ret;
3460        compat_old_sigset_t mask;
3461        compat_uptr_t handler, restorer;
3462
3463        if (act) {
3464                if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3465                    __get_user(handler, &act->sa_handler) ||
3466                    __get_user(restorer, &act->sa_restorer) ||
3467                    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3468                    __get_user(mask, &act->sa_mask))
3469                        return -EFAULT;
3470
3471#ifdef __ARCH_HAS_KA_RESTORER
3472                new_ka.ka_restorer = NULL;
3473#endif
3474                new_ka.sa.sa_handler = compat_ptr(handler);
3475                new_ka.sa.sa_restorer = compat_ptr(restorer);
3476                siginitset(&new_ka.sa.sa_mask, mask);
3477        }
3478
3479        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3480
3481        if (!ret && oact) {
3482                if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3483                    __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3484                               &oact->sa_handler) ||
3485                    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3486                               &oact->sa_restorer) ||
3487                    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3488                    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3489                        return -EFAULT;
3490        }
3491        return ret;
3492}
3493#endif
3494
3495#ifdef __ARCH_WANT_SYS_SGETMASK
3496
3497/*
3498 * For backwards compatibility.  Functionality superseded by sigprocmask.
3499 */
3500SYSCALL_DEFINE0(sgetmask)
3501{
3502        /* SMP safe */
3503        return current->blocked.sig[0];
3504}
3505
3506SYSCALL_DEFINE1(ssetmask, int, newmask)
3507{
3508        int old = current->blocked.sig[0];
3509        sigset_t newset;
3510
3511        siginitset(&newset, newmask);
3512        set_current_blocked(&newset);
3513
3514        return old;
3515}
3516#endif /* __ARCH_WANT_SGETMASK */
3517
3518#ifdef __ARCH_WANT_SYS_SIGNAL
3519/*
3520 * For backwards compatibility.  Functionality superseded by sigaction.
3521 */
3522SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3523{
3524        struct k_sigaction new_sa, old_sa;
3525        int ret;
3526
3527        new_sa.sa.sa_handler = handler;
3528        new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3529        sigemptyset(&new_sa.sa.sa_mask);
3530
3531        ret = do_sigaction(sig, &new_sa, &old_sa);
3532
3533        return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3534}
3535#endif /* __ARCH_WANT_SYS_SIGNAL */
3536
3537#ifdef __ARCH_WANT_SYS_PAUSE
3538
3539SYSCALL_DEFINE0(pause)
3540{
3541        while (!signal_pending(current)) {
3542                current->state = TASK_INTERRUPTIBLE;
3543                schedule();
3544        }
3545        return -ERESTARTNOHAND;
3546}
3547
3548#endif
3549
3550int sigsuspend(sigset_t *set)
3551{
3552        current->saved_sigmask = current->blocked;
3553        set_current_blocked(set);
3554
3555        current->state = TASK_INTERRUPTIBLE;
3556        schedule();
3557        set_restore_sigmask();
3558        return -ERESTARTNOHAND;
3559}
3560
3561/**
3562 *  sys_rt_sigsuspend - replace the signal mask for a value with the
3563 *      @unewset value until a signal is received
3564 *  @unewset: new signal mask value
3565 *  @sigsetsize: size of sigset_t type
3566 */
3567SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3568{
3569        sigset_t newset;
3570
3571        /* XXX: Don't preclude handling different sized sigset_t's.  */
3572        if (sigsetsize != sizeof(sigset_t))
3573                return -EINVAL;
3574
3575        if (copy_from_user(&newset, unewset, sizeof(newset)))
3576                return -EFAULT;
3577        return sigsuspend(&newset);
3578}
3579 
3580#ifdef CONFIG_COMPAT
3581COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3582{
3583#ifdef __BIG_ENDIAN
3584        sigset_t newset;
3585        compat_sigset_t newset32;
3586
3587        /* XXX: Don't preclude handling different sized sigset_t's.  */
3588        if (sigsetsize != sizeof(sigset_t))
3589                return -EINVAL;
3590
3591        if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
3592                return -EFAULT;
3593        sigset_from_compat(&newset, &newset32);
3594        return sigsuspend(&newset);
3595#else
3596        /* on little-endian bitmaps don't care about granularity */
3597        return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
3598#endif
3599}
3600#endif
3601
3602#ifdef CONFIG_OLD_SIGSUSPEND
3603SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3604{
3605        sigset_t blocked;
3606        siginitset(&blocked, mask);
3607        return sigsuspend(&blocked);
3608}
3609#endif
3610#ifdef CONFIG_OLD_SIGSUSPEND3
3611SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3612{
3613        sigset_t blocked;
3614        siginitset(&blocked, mask);
3615        return sigsuspend(&blocked);
3616}
3617#endif
3618
3619__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
3620{
3621        return NULL;
3622}
3623
3624void __init signals_init(void)
3625{
3626        sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
3627}
3628
3629#ifdef CONFIG_KGDB_KDB
3630#include <linux/kdb.h>
3631/*
3632 * kdb_send_sig_info - Allows kdb to send signals without exposing
3633 * signal internals.  This function checks if the required locks are
3634 * available before calling the main signal code, to avoid kdb
3635 * deadlocks.
3636 */
3637void
3638kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
3639{
3640        static struct task_struct *kdb_prev_t;
3641        int sig, new_t;
3642        if (!spin_trylock(&t->sighand->siglock)) {
3643                kdb_printf("Can't do kill command now.\n"
3644                           "The sigmask lock is held somewhere else in "
3645                           "kernel, try again later\n");
3646                return;
3647        }
3648        spin_unlock(&t->sighand->siglock);
3649        new_t = kdb_prev_t != t;
3650        kdb_prev_t = t;
3651        if (t->state != TASK_RUNNING && new_t) {
3652                kdb_printf("Process is not RUNNING, sending a signal from "
3653                           "kdb risks deadlock\n"
3654                           "on the run queue locks. "
3655                           "The signal has _not_ been sent.\n"
3656                           "Reissue the kill command if you want to risk "
3657                           "the deadlock.\n");
3658                return;
3659        }
3660        sig = info->si_signo;
3661        if (send_sig_info(sig, info, t))
3662                kdb_printf("Fail to deliver Signal %d to process %d.\n",
3663                           sig, t->pid);
3664        else
3665                kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
3666}
3667#endif  /* CONFIG_KGDB_KDB */
3668
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