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v4.17
 
   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/mm.h>
  17#include <linux/sched/user.h>
  18#include <linux/sched/debug.h>
  19#include <linux/sched/task.h>
  20#include <linux/sched/task_stack.h>
  21#include <linux/sched/cputime.h>
 
  22#include <linux/fs.h>
 
 
  23#include <linux/tty.h>
  24#include <linux/binfmts.h>
  25#include <linux/coredump.h>
  26#include <linux/security.h>
  27#include <linux/syscalls.h>
  28#include <linux/ptrace.h>
  29#include <linux/signal.h>
  30#include <linux/signalfd.h>
  31#include <linux/ratelimit.h>
  32#include <linux/tracehook.h>
  33#include <linux/capability.h>
  34#include <linux/freezer.h>
  35#include <linux/pid_namespace.h>
  36#include <linux/nsproxy.h>
  37#include <linux/user_namespace.h>
  38#include <linux/uprobes.h>
  39#include <linux/compat.h>
  40#include <linux/cn_proc.h>
  41#include <linux/compiler.h>
  42#include <linux/posix-timers.h>
  43#include <linux/livepatch.h>
 
 
 
  44
  45#define CREATE_TRACE_POINTS
  46#include <trace/events/signal.h>
  47
  48#include <asm/param.h>
  49#include <linux/uaccess.h>
  50#include <asm/unistd.h>
  51#include <asm/siginfo.h>
  52#include <asm/cacheflush.h>
  53#include "audit.h"	/* audit_signal_info() */
  54
  55/*
  56 * SLAB caches for signal bits.
  57 */
  58
  59static struct kmem_cache *sigqueue_cachep;
  60
  61int print_fatal_signals __read_mostly;
  62
  63static void __user *sig_handler(struct task_struct *t, int sig)
  64{
  65	return t->sighand->action[sig - 1].sa.sa_handler;
  66}
  67
  68static int sig_handler_ignored(void __user *handler, int sig)
  69{
  70	/* Is it explicitly or implicitly ignored? */
  71	return handler == SIG_IGN ||
  72		(handler == SIG_DFL && sig_kernel_ignore(sig));
  73}
  74
  75static int sig_task_ignored(struct task_struct *t, int sig, bool force)
  76{
  77	void __user *handler;
  78
  79	handler = sig_handler(t, sig);
  80
 
 
 
 
  81	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
  82	    handler == SIG_DFL && !(force && sig_kernel_only(sig)))
  83		return 1;
 
 
 
 
 
  84
  85	return sig_handler_ignored(handler, sig);
  86}
  87
  88static int sig_ignored(struct task_struct *t, int sig, bool force)
  89{
  90	/*
  91	 * Blocked signals are never ignored, since the
  92	 * signal handler may change by the time it is
  93	 * unblocked.
  94	 */
  95	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
  96		return 0;
  97
  98	/*
  99	 * Tracers may want to know about even ignored signal unless it
 100	 * is SIGKILL which can't be reported anyway but can be ignored
 101	 * by SIGNAL_UNKILLABLE task.
 102	 */
 103	if (t->ptrace && sig != SIGKILL)
 104		return 0;
 105
 106	return sig_task_ignored(t, sig, force);
 107}
 108
 109/*
 110 * Re-calculate pending state from the set of locally pending
 111 * signals, globally pending signals, and blocked signals.
 112 */
 113static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
 114{
 115	unsigned long ready;
 116	long i;
 117
 118	switch (_NSIG_WORDS) {
 119	default:
 120		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
 121			ready |= signal->sig[i] &~ blocked->sig[i];
 122		break;
 123
 124	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
 125		ready |= signal->sig[2] &~ blocked->sig[2];
 126		ready |= signal->sig[1] &~ blocked->sig[1];
 127		ready |= signal->sig[0] &~ blocked->sig[0];
 128		break;
 129
 130	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
 131		ready |= signal->sig[0] &~ blocked->sig[0];
 132		break;
 133
 134	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
 135	}
 136	return ready !=	0;
 137}
 138
 139#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
 140
 141static int recalc_sigpending_tsk(struct task_struct *t)
 142{
 143	if ((t->jobctl & JOBCTL_PENDING_MASK) ||
 144	    PENDING(&t->pending, &t->blocked) ||
 145	    PENDING(&t->signal->shared_pending, &t->blocked)) {
 
 146		set_tsk_thread_flag(t, TIF_SIGPENDING);
 147		return 1;
 148	}
 
 149	/*
 150	 * We must never clear the flag in another thread, or in current
 151	 * when it's possible the current syscall is returning -ERESTART*.
 152	 * So we don't clear it here, and only callers who know they should do.
 153	 */
 154	return 0;
 155}
 156
 157/*
 158 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
 159 * This is superfluous when called on current, the wakeup is a harmless no-op.
 160 */
 161void recalc_sigpending_and_wake(struct task_struct *t)
 162{
 163	if (recalc_sigpending_tsk(t))
 164		signal_wake_up(t, 0);
 165}
 166
 167void recalc_sigpending(void)
 168{
 169	if (!recalc_sigpending_tsk(current) && !freezing(current) &&
 170	    !klp_patch_pending(current))
 171		clear_thread_flag(TIF_SIGPENDING);
 172
 173}
 
 
 
 
 
 
 
 
 
 
 
 
 174
 175/* Given the mask, find the first available signal that should be serviced. */
 176
 177#define SYNCHRONOUS_MASK \
 178	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
 179	 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
 180
 181int next_signal(struct sigpending *pending, sigset_t *mask)
 182{
 183	unsigned long i, *s, *m, x;
 184	int sig = 0;
 185
 186	s = pending->signal.sig;
 187	m = mask->sig;
 188
 189	/*
 190	 * Handle the first word specially: it contains the
 191	 * synchronous signals that need to be dequeued first.
 192	 */
 193	x = *s &~ *m;
 194	if (x) {
 195		if (x & SYNCHRONOUS_MASK)
 196			x &= SYNCHRONOUS_MASK;
 197		sig = ffz(~x) + 1;
 198		return sig;
 199	}
 200
 201	switch (_NSIG_WORDS) {
 202	default:
 203		for (i = 1; i < _NSIG_WORDS; ++i) {
 204			x = *++s &~ *++m;
 205			if (!x)
 206				continue;
 207			sig = ffz(~x) + i*_NSIG_BPW + 1;
 208			break;
 209		}
 210		break;
 211
 212	case 2:
 213		x = s[1] &~ m[1];
 214		if (!x)
 215			break;
 216		sig = ffz(~x) + _NSIG_BPW + 1;
 217		break;
 218
 219	case 1:
 220		/* Nothing to do */
 221		break;
 222	}
 223
 224	return sig;
 225}
 226
 227static inline void print_dropped_signal(int sig)
 228{
 229	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
 230
 231	if (!print_fatal_signals)
 232		return;
 233
 234	if (!__ratelimit(&ratelimit_state))
 235		return;
 236
 237	pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
 238				current->comm, current->pid, sig);
 239}
 240
 241/**
 242 * task_set_jobctl_pending - set jobctl pending bits
 243 * @task: target task
 244 * @mask: pending bits to set
 245 *
 246 * Clear @mask from @task->jobctl.  @mask must be subset of
 247 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
 248 * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
 249 * cleared.  If @task is already being killed or exiting, this function
 250 * becomes noop.
 251 *
 252 * CONTEXT:
 253 * Must be called with @task->sighand->siglock held.
 254 *
 255 * RETURNS:
 256 * %true if @mask is set, %false if made noop because @task was dying.
 257 */
 258bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
 259{
 260	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
 261			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
 262	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
 263
 264	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
 265		return false;
 266
 267	if (mask & JOBCTL_STOP_SIGMASK)
 268		task->jobctl &= ~JOBCTL_STOP_SIGMASK;
 269
 270	task->jobctl |= mask;
 271	return true;
 272}
 273
 274/**
 275 * task_clear_jobctl_trapping - clear jobctl trapping bit
 276 * @task: target task
 277 *
 278 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
 279 * Clear it and wake up the ptracer.  Note that we don't need any further
 280 * locking.  @task->siglock guarantees that @task->parent points to the
 281 * ptracer.
 282 *
 283 * CONTEXT:
 284 * Must be called with @task->sighand->siglock held.
 285 */
 286void task_clear_jobctl_trapping(struct task_struct *task)
 287{
 288	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
 289		task->jobctl &= ~JOBCTL_TRAPPING;
 290		smp_mb();	/* advised by wake_up_bit() */
 291		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
 292	}
 293}
 294
 295/**
 296 * task_clear_jobctl_pending - clear jobctl pending bits
 297 * @task: target task
 298 * @mask: pending bits to clear
 299 *
 300 * Clear @mask from @task->jobctl.  @mask must be subset of
 301 * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
 302 * STOP bits are cleared together.
 303 *
 304 * If clearing of @mask leaves no stop or trap pending, this function calls
 305 * task_clear_jobctl_trapping().
 306 *
 307 * CONTEXT:
 308 * Must be called with @task->sighand->siglock held.
 309 */
 310void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
 311{
 312	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
 313
 314	if (mask & JOBCTL_STOP_PENDING)
 315		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
 316
 317	task->jobctl &= ~mask;
 318
 319	if (!(task->jobctl & JOBCTL_PENDING_MASK))
 320		task_clear_jobctl_trapping(task);
 321}
 322
 323/**
 324 * task_participate_group_stop - participate in a group stop
 325 * @task: task participating in a group stop
 326 *
 327 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
 328 * Group stop states are cleared and the group stop count is consumed if
 329 * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
 330 * stop, the appropriate %SIGNAL_* flags are set.
 331 *
 332 * CONTEXT:
 333 * Must be called with @task->sighand->siglock held.
 334 *
 335 * RETURNS:
 336 * %true if group stop completion should be notified to the parent, %false
 337 * otherwise.
 338 */
 339static bool task_participate_group_stop(struct task_struct *task)
 340{
 341	struct signal_struct *sig = task->signal;
 342	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
 343
 344	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
 345
 346	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
 347
 348	if (!consume)
 349		return false;
 350
 351	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
 352		sig->group_stop_count--;
 353
 354	/*
 355	 * Tell the caller to notify completion iff we are entering into a
 356	 * fresh group stop.  Read comment in do_signal_stop() for details.
 357	 */
 358	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
 359		signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
 360		return true;
 361	}
 362	return false;
 363}
 364
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 365/*
 366 * allocate a new signal queue record
 367 * - this may be called without locks if and only if t == current, otherwise an
 368 *   appropriate lock must be held to stop the target task from exiting
 369 */
 370static struct sigqueue *
 371__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
 
 372{
 373	struct sigqueue *q = NULL;
 374	struct user_struct *user;
 
 375
 376	/*
 377	 * Protect access to @t credentials. This can go away when all
 378	 * callers hold rcu read lock.
 
 
 
 
 379	 */
 380	rcu_read_lock();
 381	user = get_uid(__task_cred(t)->user);
 382	atomic_inc(&user->sigpending);
 383	rcu_read_unlock();
 
 
 384
 385	if (override_rlimit ||
 386	    atomic_read(&user->sigpending) <=
 387			task_rlimit(t, RLIMIT_SIGPENDING)) {
 388		q = kmem_cache_alloc(sigqueue_cachep, flags);
 389	} else {
 390		print_dropped_signal(sig);
 391	}
 392
 393	if (unlikely(q == NULL)) {
 394		atomic_dec(&user->sigpending);
 395		free_uid(user);
 396	} else {
 397		INIT_LIST_HEAD(&q->list);
 398		q->flags = 0;
 399		q->user = user;
 400	}
 401
 402	return q;
 403}
 404
 405static void __sigqueue_free(struct sigqueue *q)
 406{
 407	if (q->flags & SIGQUEUE_PREALLOC)
 408		return;
 409	atomic_dec(&q->user->sigpending);
 410	free_uid(q->user);
 
 
 411	kmem_cache_free(sigqueue_cachep, q);
 412}
 413
 414void flush_sigqueue(struct sigpending *queue)
 415{
 416	struct sigqueue *q;
 417
 418	sigemptyset(&queue->signal);
 419	while (!list_empty(&queue->list)) {
 420		q = list_entry(queue->list.next, struct sigqueue , list);
 421		list_del_init(&q->list);
 422		__sigqueue_free(q);
 423	}
 424}
 425
 426/*
 427 * Flush all pending signals for this kthread.
 428 */
 429void flush_signals(struct task_struct *t)
 430{
 431	unsigned long flags;
 432
 433	spin_lock_irqsave(&t->sighand->siglock, flags);
 434	clear_tsk_thread_flag(t, TIF_SIGPENDING);
 435	flush_sigqueue(&t->pending);
 436	flush_sigqueue(&t->signal->shared_pending);
 437	spin_unlock_irqrestore(&t->sighand->siglock, flags);
 438}
 
 439
 440#ifdef CONFIG_POSIX_TIMERS
 441static void __flush_itimer_signals(struct sigpending *pending)
 442{
 443	sigset_t signal, retain;
 444	struct sigqueue *q, *n;
 445
 446	signal = pending->signal;
 447	sigemptyset(&retain);
 448
 449	list_for_each_entry_safe(q, n, &pending->list, list) {
 450		int sig = q->info.si_signo;
 451
 452		if (likely(q->info.si_code != SI_TIMER)) {
 453			sigaddset(&retain, sig);
 454		} else {
 455			sigdelset(&signal, sig);
 456			list_del_init(&q->list);
 457			__sigqueue_free(q);
 458		}
 459	}
 460
 461	sigorsets(&pending->signal, &signal, &retain);
 462}
 463
 464void flush_itimer_signals(void)
 465{
 466	struct task_struct *tsk = current;
 467	unsigned long flags;
 468
 469	spin_lock_irqsave(&tsk->sighand->siglock, flags);
 470	__flush_itimer_signals(&tsk->pending);
 471	__flush_itimer_signals(&tsk->signal->shared_pending);
 472	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 473}
 474#endif
 475
 476void ignore_signals(struct task_struct *t)
 477{
 478	int i;
 479
 480	for (i = 0; i < _NSIG; ++i)
 481		t->sighand->action[i].sa.sa_handler = SIG_IGN;
 482
 483	flush_signals(t);
 484}
 485
 486/*
 487 * Flush all handlers for a task.
 488 */
 489
 490void
 491flush_signal_handlers(struct task_struct *t, int force_default)
 492{
 493	int i;
 494	struct k_sigaction *ka = &t->sighand->action[0];
 495	for (i = _NSIG ; i != 0 ; i--) {
 496		if (force_default || ka->sa.sa_handler != SIG_IGN)
 497			ka->sa.sa_handler = SIG_DFL;
 498		ka->sa.sa_flags = 0;
 499#ifdef __ARCH_HAS_SA_RESTORER
 500		ka->sa.sa_restorer = NULL;
 501#endif
 502		sigemptyset(&ka->sa.sa_mask);
 503		ka++;
 504	}
 505}
 506
 507int unhandled_signal(struct task_struct *tsk, int sig)
 508{
 509	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
 510	if (is_global_init(tsk))
 511		return 1;
 
 512	if (handler != SIG_IGN && handler != SIG_DFL)
 513		return 0;
 
 
 
 
 
 514	/* if ptraced, let the tracer determine */
 515	return !tsk->ptrace;
 516}
 517
 518static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
 519			   bool *resched_timer)
 520{
 521	struct sigqueue *q, *first = NULL;
 522
 523	/*
 524	 * Collect the siginfo appropriate to this signal.  Check if
 525	 * there is another siginfo for the same signal.
 526	*/
 527	list_for_each_entry(q, &list->list, list) {
 528		if (q->info.si_signo == sig) {
 529			if (first)
 530				goto still_pending;
 531			first = q;
 532		}
 533	}
 534
 535	sigdelset(&list->signal, sig);
 536
 537	if (first) {
 538still_pending:
 539		list_del_init(&first->list);
 540		copy_siginfo(info, &first->info);
 541
 542		*resched_timer =
 543			(first->flags & SIGQUEUE_PREALLOC) &&
 544			(info->si_code == SI_TIMER) &&
 545			(info->si_sys_private);
 546
 547		__sigqueue_free(first);
 548	} else {
 549		/*
 550		 * Ok, it wasn't in the queue.  This must be
 551		 * a fast-pathed signal or we must have been
 552		 * out of queue space.  So zero out the info.
 553		 */
 554		clear_siginfo(info);
 555		info->si_signo = sig;
 556		info->si_errno = 0;
 557		info->si_code = SI_USER;
 558		info->si_pid = 0;
 559		info->si_uid = 0;
 560	}
 561}
 562
 563static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
 564			siginfo_t *info, bool *resched_timer)
 565{
 566	int sig = next_signal(pending, mask);
 567
 568	if (sig)
 569		collect_signal(sig, pending, info, resched_timer);
 570	return sig;
 571}
 572
 573/*
 574 * Dequeue a signal and return the element to the caller, which is
 575 * expected to free it.
 576 *
 577 * All callers have to hold the siglock.
 578 */
 579int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
 
 580{
 581	bool resched_timer = false;
 582	int signr;
 583
 584	/* We only dequeue private signals from ourselves, we don't let
 585	 * signalfd steal them
 586	 */
 
 587	signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
 588	if (!signr) {
 
 589		signr = __dequeue_signal(&tsk->signal->shared_pending,
 590					 mask, info, &resched_timer);
 591#ifdef CONFIG_POSIX_TIMERS
 592		/*
 593		 * itimer signal ?
 594		 *
 595		 * itimers are process shared and we restart periodic
 596		 * itimers in the signal delivery path to prevent DoS
 597		 * attacks in the high resolution timer case. This is
 598		 * compliant with the old way of self-restarting
 599		 * itimers, as the SIGALRM is a legacy signal and only
 600		 * queued once. Changing the restart behaviour to
 601		 * restart the timer in the signal dequeue path is
 602		 * reducing the timer noise on heavy loaded !highres
 603		 * systems too.
 604		 */
 605		if (unlikely(signr == SIGALRM)) {
 606			struct hrtimer *tmr = &tsk->signal->real_timer;
 607
 608			if (!hrtimer_is_queued(tmr) &&
 609			    tsk->signal->it_real_incr != 0) {
 610				hrtimer_forward(tmr, tmr->base->get_time(),
 611						tsk->signal->it_real_incr);
 612				hrtimer_restart(tmr);
 613			}
 614		}
 615#endif
 616	}
 617
 618	recalc_sigpending();
 619	if (!signr)
 620		return 0;
 621
 622	if (unlikely(sig_kernel_stop(signr))) {
 623		/*
 624		 * Set a marker that we have dequeued a stop signal.  Our
 625		 * caller might release the siglock and then the pending
 626		 * stop signal it is about to process is no longer in the
 627		 * pending bitmasks, but must still be cleared by a SIGCONT
 628		 * (and overruled by a SIGKILL).  So those cases clear this
 629		 * shared flag after we've set it.  Note that this flag may
 630		 * remain set after the signal we return is ignored or
 631		 * handled.  That doesn't matter because its only purpose
 632		 * is to alert stop-signal processing code when another
 633		 * processor has come along and cleared the flag.
 634		 */
 635		current->jobctl |= JOBCTL_STOP_DEQUEUED;
 636	}
 637#ifdef CONFIG_POSIX_TIMERS
 638	if (resched_timer) {
 639		/*
 640		 * Release the siglock to ensure proper locking order
 641		 * of timer locks outside of siglocks.  Note, we leave
 642		 * irqs disabled here, since the posix-timers code is
 643		 * about to disable them again anyway.
 644		 */
 645		spin_unlock(&tsk->sighand->siglock);
 646		posixtimer_rearm(info);
 647		spin_lock(&tsk->sighand->siglock);
 648
 649		/* Don't expose the si_sys_private value to userspace */
 650		info->si_sys_private = 0;
 651	}
 652#endif
 653	return signr;
 654}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 655
 656/*
 657 * Tell a process that it has a new active signal..
 658 *
 659 * NOTE! we rely on the previous spin_lock to
 660 * lock interrupts for us! We can only be called with
 661 * "siglock" held, and the local interrupt must
 662 * have been disabled when that got acquired!
 663 *
 664 * No need to set need_resched since signal event passing
 665 * goes through ->blocked
 666 */
 667void signal_wake_up_state(struct task_struct *t, unsigned int state)
 668{
 
 
 669	set_tsk_thread_flag(t, TIF_SIGPENDING);
 
 670	/*
 671	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
 672	 * case. We don't check t->state here because there is a race with it
 673	 * executing another processor and just now entering stopped state.
 674	 * By using wake_up_state, we ensure the process will wake up and
 675	 * handle its death signal.
 676	 */
 677	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
 678		kick_process(t);
 679}
 680
 681/*
 682 * Remove signals in mask from the pending set and queue.
 683 * Returns 1 if any signals were found.
 684 *
 685 * All callers must be holding the siglock.
 686 */
 687static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
 688{
 689	struct sigqueue *q, *n;
 690	sigset_t m;
 691
 692	sigandsets(&m, mask, &s->signal);
 693	if (sigisemptyset(&m))
 694		return 0;
 695
 696	sigandnsets(&s->signal, &s->signal, mask);
 697	list_for_each_entry_safe(q, n, &s->list, list) {
 698		if (sigismember(mask, q->info.si_signo)) {
 699			list_del_init(&q->list);
 700			__sigqueue_free(q);
 701		}
 702	}
 703	return 1;
 704}
 705
 706static inline int is_si_special(const struct siginfo *info)
 707{
 708	return info <= SEND_SIG_FORCED;
 709}
 710
 711static inline bool si_fromuser(const struct siginfo *info)
 712{
 713	return info == SEND_SIG_NOINFO ||
 714		(!is_si_special(info) && SI_FROMUSER(info));
 715}
 716
 717/*
 718 * called with RCU read lock from check_kill_permission()
 719 */
 720static int kill_ok_by_cred(struct task_struct *t)
 721{
 722	const struct cred *cred = current_cred();
 723	const struct cred *tcred = __task_cred(t);
 724
 725	if (uid_eq(cred->euid, tcred->suid) ||
 726	    uid_eq(cred->euid, tcred->uid)  ||
 727	    uid_eq(cred->uid,  tcred->suid) ||
 728	    uid_eq(cred->uid,  tcred->uid))
 729		return 1;
 730
 731	if (ns_capable(tcred->user_ns, CAP_KILL))
 732		return 1;
 733
 734	return 0;
 735}
 736
 737/*
 738 * Bad permissions for sending the signal
 739 * - the caller must hold the RCU read lock
 740 */
 741static int check_kill_permission(int sig, struct siginfo *info,
 742				 struct task_struct *t)
 743{
 744	struct pid *sid;
 745	int error;
 746
 747	if (!valid_signal(sig))
 748		return -EINVAL;
 749
 750	if (!si_fromuser(info))
 751		return 0;
 752
 753	error = audit_signal_info(sig, t); /* Let audit system see the signal */
 754	if (error)
 755		return error;
 756
 757	if (!same_thread_group(current, t) &&
 758	    !kill_ok_by_cred(t)) {
 759		switch (sig) {
 760		case SIGCONT:
 761			sid = task_session(t);
 762			/*
 763			 * We don't return the error if sid == NULL. The
 764			 * task was unhashed, the caller must notice this.
 765			 */
 766			if (!sid || sid == task_session(current))
 767				break;
 
 768		default:
 769			return -EPERM;
 770		}
 771	}
 772
 773	return security_task_kill(t, info, sig, NULL);
 774}
 775
 776/**
 777 * ptrace_trap_notify - schedule trap to notify ptracer
 778 * @t: tracee wanting to notify tracer
 779 *
 780 * This function schedules sticky ptrace trap which is cleared on the next
 781 * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
 782 * ptracer.
 783 *
 784 * If @t is running, STOP trap will be taken.  If trapped for STOP and
 785 * ptracer is listening for events, tracee is woken up so that it can
 786 * re-trap for the new event.  If trapped otherwise, STOP trap will be
 787 * eventually taken without returning to userland after the existing traps
 788 * are finished by PTRACE_CONT.
 789 *
 790 * CONTEXT:
 791 * Must be called with @task->sighand->siglock held.
 792 */
 793static void ptrace_trap_notify(struct task_struct *t)
 794{
 795	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
 796	assert_spin_locked(&t->sighand->siglock);
 797
 798	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
 799	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
 800}
 801
 802/*
 803 * Handle magic process-wide effects of stop/continue signals. Unlike
 804 * the signal actions, these happen immediately at signal-generation
 805 * time regardless of blocking, ignoring, or handling.  This does the
 806 * actual continuing for SIGCONT, but not the actual stopping for stop
 807 * signals. The process stop is done as a signal action for SIG_DFL.
 808 *
 809 * Returns true if the signal should be actually delivered, otherwise
 810 * it should be dropped.
 811 */
 812static bool prepare_signal(int sig, struct task_struct *p, bool force)
 813{
 814	struct signal_struct *signal = p->signal;
 815	struct task_struct *t;
 816	sigset_t flush;
 817
 818	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
 819		if (!(signal->flags & SIGNAL_GROUP_EXIT))
 820			return sig == SIGKILL;
 821		/*
 822		 * The process is in the middle of dying, nothing to do.
 823		 */
 
 824	} else if (sig_kernel_stop(sig)) {
 825		/*
 826		 * This is a stop signal.  Remove SIGCONT from all queues.
 827		 */
 828		siginitset(&flush, sigmask(SIGCONT));
 829		flush_sigqueue_mask(&flush, &signal->shared_pending);
 830		for_each_thread(p, t)
 831			flush_sigqueue_mask(&flush, &t->pending);
 832	} else if (sig == SIGCONT) {
 833		unsigned int why;
 834		/*
 835		 * Remove all stop signals from all queues, wake all threads.
 836		 */
 837		siginitset(&flush, SIG_KERNEL_STOP_MASK);
 838		flush_sigqueue_mask(&flush, &signal->shared_pending);
 839		for_each_thread(p, t) {
 840			flush_sigqueue_mask(&flush, &t->pending);
 841			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
 842			if (likely(!(t->ptrace & PT_SEIZED)))
 
 843				wake_up_state(t, __TASK_STOPPED);
 844			else
 845				ptrace_trap_notify(t);
 846		}
 847
 848		/*
 849		 * Notify the parent with CLD_CONTINUED if we were stopped.
 850		 *
 851		 * If we were in the middle of a group stop, we pretend it
 852		 * was already finished, and then continued. Since SIGCHLD
 853		 * doesn't queue we report only CLD_STOPPED, as if the next
 854		 * CLD_CONTINUED was dropped.
 855		 */
 856		why = 0;
 857		if (signal->flags & SIGNAL_STOP_STOPPED)
 858			why |= SIGNAL_CLD_CONTINUED;
 859		else if (signal->group_stop_count)
 860			why |= SIGNAL_CLD_STOPPED;
 861
 862		if (why) {
 863			/*
 864			 * The first thread which returns from do_signal_stop()
 865			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
 866			 * notify its parent. See get_signal_to_deliver().
 867			 */
 868			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
 869			signal->group_stop_count = 0;
 870			signal->group_exit_code = 0;
 871		}
 872	}
 873
 874	return !sig_ignored(p, sig, force);
 875}
 876
 877/*
 878 * Test if P wants to take SIG.  After we've checked all threads with this,
 879 * it's equivalent to finding no threads not blocking SIG.  Any threads not
 880 * blocking SIG were ruled out because they are not running and already
 881 * have pending signals.  Such threads will dequeue from the shared queue
 882 * as soon as they're available, so putting the signal on the shared queue
 883 * will be equivalent to sending it to one such thread.
 884 */
 885static inline int wants_signal(int sig, struct task_struct *p)
 886{
 887	if (sigismember(&p->blocked, sig))
 888		return 0;
 
 889	if (p->flags & PF_EXITING)
 890		return 0;
 
 891	if (sig == SIGKILL)
 892		return 1;
 
 893	if (task_is_stopped_or_traced(p))
 894		return 0;
 895	return task_curr(p) || !signal_pending(p);
 
 896}
 897
 898static void complete_signal(int sig, struct task_struct *p, int group)
 899{
 900	struct signal_struct *signal = p->signal;
 901	struct task_struct *t;
 902
 903	/*
 904	 * Now find a thread we can wake up to take the signal off the queue.
 905	 *
 906	 * If the main thread wants the signal, it gets first crack.
 907	 * Probably the least surprising to the average bear.
 908	 */
 909	if (wants_signal(sig, p))
 910		t = p;
 911	else if (!group || thread_group_empty(p))
 912		/*
 913		 * There is just one thread and it does not need to be woken.
 914		 * It will dequeue unblocked signals before it runs again.
 915		 */
 916		return;
 917	else {
 918		/*
 919		 * Otherwise try to find a suitable thread.
 920		 */
 921		t = signal->curr_target;
 922		while (!wants_signal(sig, t)) {
 923			t = next_thread(t);
 924			if (t == signal->curr_target)
 925				/*
 926				 * No thread needs to be woken.
 927				 * Any eligible threads will see
 928				 * the signal in the queue soon.
 929				 */
 930				return;
 931		}
 932		signal->curr_target = t;
 933	}
 934
 935	/*
 936	 * Found a killable thread.  If the signal will be fatal,
 937	 * then start taking the whole group down immediately.
 938	 */
 939	if (sig_fatal(p, sig) &&
 940	    !(signal->flags & SIGNAL_GROUP_EXIT) &&
 941	    !sigismember(&t->real_blocked, sig) &&
 942	    (sig == SIGKILL || !p->ptrace)) {
 943		/*
 944		 * This signal will be fatal to the whole group.
 945		 */
 946		if (!sig_kernel_coredump(sig)) {
 947			/*
 948			 * Start a group exit and wake everybody up.
 949			 * This way we don't have other threads
 950			 * running and doing things after a slower
 951			 * thread has the fatal signal pending.
 952			 */
 953			signal->flags = SIGNAL_GROUP_EXIT;
 954			signal->group_exit_code = sig;
 955			signal->group_stop_count = 0;
 956			t = p;
 957			do {
 958				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
 959				sigaddset(&t->pending.signal, SIGKILL);
 960				signal_wake_up(t, 1);
 961			} while_each_thread(p, t);
 962			return;
 963		}
 964	}
 965
 966	/*
 967	 * The signal is already in the shared-pending queue.
 968	 * Tell the chosen thread to wake up and dequeue it.
 969	 */
 970	signal_wake_up(t, sig == SIGKILL);
 971	return;
 972}
 973
 974static inline int legacy_queue(struct sigpending *signals, int sig)
 975{
 976	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
 977}
 978
 979#ifdef CONFIG_USER_NS
 980static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
 981{
 982	if (current_user_ns() == task_cred_xxx(t, user_ns))
 983		return;
 984
 985	if (SI_FROMKERNEL(info))
 986		return;
 987
 988	rcu_read_lock();
 989	info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
 990					make_kuid(current_user_ns(), info->si_uid));
 991	rcu_read_unlock();
 992}
 993#else
 994static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
 995{
 996	return;
 997}
 998#endif
 999
1000static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
1001			int group, int from_ancestor_ns)
1002{
1003	struct sigpending *pending;
1004	struct sigqueue *q;
1005	int override_rlimit;
1006	int ret = 0, result;
1007
1008	assert_spin_locked(&t->sighand->siglock);
1009
1010	result = TRACE_SIGNAL_IGNORED;
1011	if (!prepare_signal(sig, t,
1012			from_ancestor_ns || (info == SEND_SIG_FORCED)))
1013		goto ret;
1014
1015	pending = group ? &t->signal->shared_pending : &t->pending;
1016	/*
1017	 * Short-circuit ignored signals and support queuing
1018	 * exactly one non-rt signal, so that we can get more
1019	 * detailed information about the cause of the signal.
1020	 */
1021	result = TRACE_SIGNAL_ALREADY_PENDING;
1022	if (legacy_queue(pending, sig))
1023		goto ret;
1024
1025	result = TRACE_SIGNAL_DELIVERED;
1026	/*
1027	 * fast-pathed signals for kernel-internal things like SIGSTOP
1028	 * or SIGKILL.
1029	 */
1030	if (info == SEND_SIG_FORCED)
1031		goto out_set;
1032
1033	/*
1034	 * Real-time signals must be queued if sent by sigqueue, or
1035	 * some other real-time mechanism.  It is implementation
1036	 * defined whether kill() does so.  We attempt to do so, on
1037	 * the principle of least surprise, but since kill is not
1038	 * allowed to fail with EAGAIN when low on memory we just
1039	 * make sure at least one signal gets delivered and don't
1040	 * pass on the info struct.
1041	 */
1042	if (sig < SIGRTMIN)
1043		override_rlimit = (is_si_special(info) || info->si_code >= 0);
1044	else
1045		override_rlimit = 0;
1046
1047	q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
 
1048	if (q) {
1049		list_add_tail(&q->list, &pending->list);
1050		switch ((unsigned long) info) {
1051		case (unsigned long) SEND_SIG_NOINFO:
1052			clear_siginfo(&q->info);
1053			q->info.si_signo = sig;
1054			q->info.si_errno = 0;
1055			q->info.si_code = SI_USER;
1056			q->info.si_pid = task_tgid_nr_ns(current,
1057							task_active_pid_ns(t));
1058			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 
 
 
 
1059			break;
1060		case (unsigned long) SEND_SIG_PRIV:
1061			clear_siginfo(&q->info);
1062			q->info.si_signo = sig;
1063			q->info.si_errno = 0;
1064			q->info.si_code = SI_KERNEL;
1065			q->info.si_pid = 0;
1066			q->info.si_uid = 0;
1067			break;
1068		default:
1069			copy_siginfo(&q->info, info);
1070			if (from_ancestor_ns)
1071				q->info.si_pid = 0;
1072			break;
1073		}
1074
1075		userns_fixup_signal_uid(&q->info, t);
1076
1077	} else if (!is_si_special(info)) {
1078		if (sig >= SIGRTMIN && info->si_code != SI_USER) {
1079			/*
1080			 * Queue overflow, abort.  We may abort if the
1081			 * signal was rt and sent by user using something
1082			 * other than kill().
1083			 */
1084			result = TRACE_SIGNAL_OVERFLOW_FAIL;
1085			ret = -EAGAIN;
1086			goto ret;
1087		} else {
1088			/*
1089			 * This is a silent loss of information.  We still
1090			 * send the signal, but the *info bits are lost.
1091			 */
1092			result = TRACE_SIGNAL_LOSE_INFO;
1093		}
1094	}
1095
1096out_set:
1097	signalfd_notify(t, sig);
1098	sigaddset(&pending->signal, sig);
1099	complete_signal(sig, t, group);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1100ret:
1101	trace_signal_generate(sig, info, t, group, result);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1102	return ret;
1103}
1104
1105static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
1106			int group)
1107{
1108	int from_ancestor_ns = 0;
 
1109
1110#ifdef CONFIG_PID_NS
1111	from_ancestor_ns = si_fromuser(info) &&
1112			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1113#endif
 
 
 
 
 
1114
1115	return __send_signal(sig, info, t, group, from_ancestor_ns);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1116}
1117
1118static void print_fatal_signal(int signr)
1119{
1120	struct pt_regs *regs = signal_pt_regs();
1121	pr_info("potentially unexpected fatal signal %d.\n", signr);
 
 
 
 
 
 
 
 
 
 
1122
1123#if defined(__i386__) && !defined(__arch_um__)
1124	pr_info("code at %08lx: ", regs->ip);
1125	{
1126		int i;
1127		for (i = 0; i < 16; i++) {
1128			unsigned char insn;
1129
1130			if (get_user(insn, (unsigned char *)(regs->ip + i)))
1131				break;
1132			pr_cont("%02x ", insn);
1133		}
1134	}
1135	pr_cont("\n");
1136#endif
1137	preempt_disable();
1138	show_regs(regs);
1139	preempt_enable();
1140}
1141
1142static int __init setup_print_fatal_signals(char *str)
1143{
1144	get_option (&str, &print_fatal_signals);
1145
1146	return 1;
1147}
1148
1149__setup("print-fatal-signals=", setup_print_fatal_signals);
1150
1151int
1152__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1153{
1154	return send_signal(sig, info, p, 1);
1155}
1156
1157static int
1158specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
1159{
1160	return send_signal(sig, info, t, 0);
1161}
1162
1163int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
1164			bool group)
1165{
1166	unsigned long flags;
1167	int ret = -ESRCH;
1168
1169	if (lock_task_sighand(p, &flags)) {
1170		ret = send_signal(sig, info, p, group);
1171		unlock_task_sighand(p, &flags);
1172	}
1173
1174	return ret;
1175}
1176
 
 
 
 
 
 
1177/*
1178 * Force a signal that the process can't ignore: if necessary
1179 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1180 *
1181 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1182 * since we do not want to have a signal handler that was blocked
1183 * be invoked when user space had explicitly blocked it.
1184 *
1185 * We don't want to have recursive SIGSEGV's etc, for example,
1186 * that is why we also clear SIGNAL_UNKILLABLE.
1187 */
1188int
1189force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
 
1190{
1191	unsigned long int flags;
1192	int ret, blocked, ignored;
1193	struct k_sigaction *action;
 
1194
1195	spin_lock_irqsave(&t->sighand->siglock, flags);
1196	action = &t->sighand->action[sig-1];
1197	ignored = action->sa.sa_handler == SIG_IGN;
1198	blocked = sigismember(&t->blocked, sig);
1199	if (blocked || ignored) {
1200		action->sa.sa_handler = SIG_DFL;
1201		if (blocked) {
 
 
1202			sigdelset(&t->blocked, sig);
1203			recalc_sigpending_and_wake(t);
1204		}
1205	}
1206	/*
1207	 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1208	 * debugging to leave init killable.
1209	 */
1210	if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
 
1211		t->signal->flags &= ~SIGNAL_UNKILLABLE;
1212	ret = specific_send_sig_info(sig, info, t);
 
 
 
1213	spin_unlock_irqrestore(&t->sighand->siglock, flags);
1214
1215	return ret;
1216}
1217
 
 
 
 
 
1218/*
1219 * Nuke all other threads in the group.
1220 */
1221int zap_other_threads(struct task_struct *p)
1222{
1223	struct task_struct *t = p;
1224	int count = 0;
1225
1226	p->signal->group_stop_count = 0;
1227
1228	while_each_thread(p, t) {
1229		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1230		count++;
 
 
1231
1232		/* Don't bother with already dead threads */
1233		if (t->exit_state)
1234			continue;
1235		sigaddset(&t->pending.signal, SIGKILL);
1236		signal_wake_up(t, 1);
1237	}
1238
1239	return count;
1240}
1241
1242struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1243					   unsigned long *flags)
1244{
1245	struct sighand_struct *sighand;
1246
 
1247	for (;;) {
1248		/*
1249		 * Disable interrupts early to avoid deadlocks.
1250		 * See rcu_read_unlock() comment header for details.
1251		 */
1252		local_irq_save(*flags);
1253		rcu_read_lock();
1254		sighand = rcu_dereference(tsk->sighand);
1255		if (unlikely(sighand == NULL)) {
1256			rcu_read_unlock();
1257			local_irq_restore(*flags);
1258			break;
1259		}
1260		/*
1261		 * This sighand can be already freed and even reused, but
1262		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1263		 * initializes ->siglock: this slab can't go away, it has
1264		 * the same object type, ->siglock can't be reinitialized.
1265		 *
1266		 * We need to ensure that tsk->sighand is still the same
1267		 * after we take the lock, we can race with de_thread() or
1268		 * __exit_signal(). In the latter case the next iteration
1269		 * must see ->sighand == NULL.
1270		 */
1271		spin_lock(&sighand->siglock);
1272		if (likely(sighand == tsk->sighand)) {
1273			rcu_read_unlock();
1274			break;
1275		}
1276		spin_unlock(&sighand->siglock);
1277		rcu_read_unlock();
1278		local_irq_restore(*flags);
1279	}
 
1280
1281	return sighand;
1282}
1283
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1284/*
1285 * send signal info to all the members of a group
 
1286 */
1287int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 
1288{
1289	int ret;
1290
1291	rcu_read_lock();
1292	ret = check_kill_permission(sig, info, p);
1293	rcu_read_unlock();
1294
1295	if (!ret && sig)
1296		ret = do_send_sig_info(sig, info, p, true);
1297
1298	return ret;
1299}
1300
1301/*
1302 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1303 * control characters do (^C, ^Z etc)
1304 * - the caller must hold at least a readlock on tasklist_lock
1305 */
1306int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
1307{
1308	struct task_struct *p = NULL;
1309	int retval, success;
1310
1311	success = 0;
1312	retval = -ESRCH;
1313	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1314		int err = group_send_sig_info(sig, info, p);
1315		success |= !err;
1316		retval = err;
 
 
 
 
 
 
1317	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1318	return success ? 0 : retval;
 
1319}
1320
1321int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
 
1322{
1323	int error = -ESRCH;
1324	struct task_struct *p;
1325
1326	for (;;) {
1327		rcu_read_lock();
1328		p = pid_task(pid, PIDTYPE_PID);
1329		if (p)
1330			error = group_send_sig_info(sig, info, p);
1331		rcu_read_unlock();
1332		if (likely(!p || error != -ESRCH))
1333			return error;
1334
1335		/*
1336		 * The task was unhashed in between, try again.  If it
1337		 * is dead, pid_task() will return NULL, if we race with
1338		 * de_thread() it will find the new leader.
1339		 */
1340	}
1341}
1342
1343static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
 
 
 
 
 
1344{
1345	int error;
1346	rcu_read_lock();
1347	error = kill_pid_info(sig, info, find_vpid(pid));
1348	rcu_read_unlock();
1349	return error;
1350}
1351
1352static int kill_as_cred_perm(const struct cred *cred,
1353			     struct task_struct *target)
1354{
1355	const struct cred *pcred = __task_cred(target);
1356	if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
1357	    !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
1358		return 0;
1359	return 1;
 
1360}
1361
1362/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1363int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
1364			 const struct cred *cred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1365{
1366	int ret = -EINVAL;
1367	struct task_struct *p;
1368	unsigned long flags;
 
1369
1370	if (!valid_signal(sig))
1371		return ret;
1372
 
 
 
 
 
 
1373	rcu_read_lock();
1374	p = pid_task(pid, PIDTYPE_PID);
1375	if (!p) {
1376		ret = -ESRCH;
1377		goto out_unlock;
1378	}
1379	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1380		ret = -EPERM;
1381		goto out_unlock;
1382	}
1383	ret = security_task_kill(p, info, sig, cred);
1384	if (ret)
1385		goto out_unlock;
1386
1387	if (sig) {
1388		if (lock_task_sighand(p, &flags)) {
1389			ret = __send_signal(sig, info, p, 1, 0);
1390			unlock_task_sighand(p, &flags);
1391		} else
1392			ret = -ESRCH;
1393	}
1394out_unlock:
1395	rcu_read_unlock();
1396	return ret;
1397}
1398EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
1399
1400/*
1401 * kill_something_info() interprets pid in interesting ways just like kill(2).
1402 *
1403 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1404 * is probably wrong.  Should make it like BSD or SYSV.
1405 */
1406
1407static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
1408{
1409	int ret;
1410
1411	if (pid > 0) {
1412		rcu_read_lock();
1413		ret = kill_pid_info(sig, info, find_vpid(pid));
1414		rcu_read_unlock();
1415		return ret;
1416	}
1417
1418	/* -INT_MIN is undefined.  Exclude this case to avoid a UBSAN warning */
1419	if (pid == INT_MIN)
1420		return -ESRCH;
1421
1422	read_lock(&tasklist_lock);
1423	if (pid != -1) {
1424		ret = __kill_pgrp_info(sig, info,
1425				pid ? find_vpid(-pid) : task_pgrp(current));
1426	} else {
1427		int retval = 0, count = 0;
1428		struct task_struct * p;
1429
1430		for_each_process(p) {
1431			if (task_pid_vnr(p) > 1 &&
1432					!same_thread_group(p, current)) {
1433				int err = group_send_sig_info(sig, info, p);
 
1434				++count;
1435				if (err != -EPERM)
1436					retval = err;
1437			}
1438		}
1439		ret = count ? retval : -ESRCH;
1440	}
1441	read_unlock(&tasklist_lock);
1442
1443	return ret;
1444}
1445
1446/*
1447 * These are for backward compatibility with the rest of the kernel source.
1448 */
1449
1450int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1451{
1452	/*
1453	 * Make sure legacy kernel users don't send in bad values
1454	 * (normal paths check this in check_kill_permission).
1455	 */
1456	if (!valid_signal(sig))
1457		return -EINVAL;
1458
1459	return do_send_sig_info(sig, info, p, false);
1460}
 
1461
1462#define __si_special(priv) \
1463	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1464
1465int
1466send_sig(int sig, struct task_struct *p, int priv)
1467{
1468	return send_sig_info(sig, __si_special(priv), p);
1469}
 
1470
1471void
1472force_sig(int sig, struct task_struct *p)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1473{
1474	force_sig_info(sig, SEND_SIG_PRIV, p);
 
 
 
 
 
 
 
 
1475}
1476
1477/*
1478 * When things go south during signal handling, we
1479 * will force a SIGSEGV. And if the signal that caused
1480 * the problem was already a SIGSEGV, we'll want to
1481 * make sure we don't even try to deliver the signal..
1482 */
1483int
1484force_sigsegv(int sig, struct task_struct *p)
1485{
1486	if (sig == SIGSEGV) {
1487		unsigned long flags;
1488		spin_lock_irqsave(&p->sighand->siglock, flags);
1489		p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1490		spin_unlock_irqrestore(&p->sighand->siglock, flags);
1491	}
1492	force_sig(SIGSEGV, p);
1493	return 0;
1494}
1495
1496int force_sig_fault(int sig, int code, void __user *addr
1497	___ARCH_SI_TRAPNO(int trapno)
1498	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1499	, struct task_struct *t)
1500{
1501	struct siginfo info;
1502
1503	clear_siginfo(&info);
1504	info.si_signo = sig;
1505	info.si_errno = 0;
1506	info.si_code  = code;
1507	info.si_addr  = addr;
1508#ifdef __ARCH_SI_TRAPNO
1509	info.si_trapno = trapno;
1510#endif
1511#ifdef __ia64__
1512	info.si_imm = imm;
1513	info.si_flags = flags;
1514	info.si_isr = isr;
1515#endif
1516	return force_sig_info(info.si_signo, &info, t);
1517}
1518
1519int send_sig_fault(int sig, int code, void __user *addr
1520	___ARCH_SI_TRAPNO(int trapno)
1521	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
1522	, struct task_struct *t)
1523{
1524	struct siginfo info;
1525
1526	clear_siginfo(&info);
1527	info.si_signo = sig;
1528	info.si_errno = 0;
1529	info.si_code  = code;
1530	info.si_addr  = addr;
1531#ifdef __ARCH_SI_TRAPNO
1532	info.si_trapno = trapno;
1533#endif
1534#ifdef __ia64__
1535	info.si_imm = imm;
1536	info.si_flags = flags;
1537	info.si_isr = isr;
1538#endif
1539	return send_sig_info(info.si_signo, &info, t);
1540}
1541
1542#if defined(BUS_MCEERR_AO) && defined(BUS_MCEERR_AR)
1543int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1544{
1545	struct siginfo info;
1546
1547	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1548	clear_siginfo(&info);
1549	info.si_signo = SIGBUS;
1550	info.si_errno = 0;
1551	info.si_code = code;
1552	info.si_addr = addr;
1553	info.si_addr_lsb = lsb;
1554	return force_sig_info(info.si_signo, &info, t);
1555}
1556
1557int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1558{
1559	struct siginfo info;
1560
1561	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1562	clear_siginfo(&info);
1563	info.si_signo = SIGBUS;
1564	info.si_errno = 0;
1565	info.si_code = code;
1566	info.si_addr = addr;
1567	info.si_addr_lsb = lsb;
1568	return send_sig_info(info.si_signo, &info, t);
1569}
1570EXPORT_SYMBOL(send_sig_mceerr);
1571#endif
1572
1573#ifdef SEGV_BNDERR
1574int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1575{
1576	struct siginfo info;
1577
1578	clear_siginfo(&info);
1579	info.si_signo = SIGSEGV;
1580	info.si_errno = 0;
1581	info.si_code  = SEGV_BNDERR;
1582	info.si_addr  = addr;
1583	info.si_lower = lower;
1584	info.si_upper = upper;
1585	return force_sig_info(info.si_signo, &info, current);
1586}
1587#endif
1588
1589#ifdef SEGV_PKUERR
1590int force_sig_pkuerr(void __user *addr, u32 pkey)
1591{
1592	struct siginfo info;
1593
1594	clear_siginfo(&info);
1595	info.si_signo = SIGSEGV;
1596	info.si_errno = 0;
1597	info.si_code  = SEGV_PKUERR;
1598	info.si_addr  = addr;
1599	info.si_pkey  = pkey;
1600	return force_sig_info(info.si_signo, &info, current);
1601}
1602#endif
1603
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1604/* For the crazy architectures that include trap information in
1605 * the errno field, instead of an actual errno value.
1606 */
1607int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1608{
1609	struct siginfo info;
1610
1611	clear_siginfo(&info);
1612	info.si_signo = SIGTRAP;
1613	info.si_errno = errno;
1614	info.si_code  = TRAP_HWBKPT;
1615	info.si_addr  = addr;
1616	return force_sig_info(info.si_signo, &info, current);
1617}
1618
1619int kill_pgrp(struct pid *pid, int sig, int priv)
 
 
 
1620{
1621	int ret;
 
 
 
 
 
 
 
 
 
1622
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1623	read_lock(&tasklist_lock);
1624	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1625	read_unlock(&tasklist_lock);
1626
1627	return ret;
1628}
 
 
 
 
 
1629EXPORT_SYMBOL(kill_pgrp);
1630
1631int kill_pid(struct pid *pid, int sig, int priv)
1632{
1633	return kill_pid_info(sig, __si_special(priv), pid);
1634}
1635EXPORT_SYMBOL(kill_pid);
1636
1637/*
1638 * These functions support sending signals using preallocated sigqueue
1639 * structures.  This is needed "because realtime applications cannot
1640 * afford to lose notifications of asynchronous events, like timer
1641 * expirations or I/O completions".  In the case of POSIX Timers
1642 * we allocate the sigqueue structure from the timer_create.  If this
1643 * allocation fails we are able to report the failure to the application
1644 * with an EAGAIN error.
1645 */
1646struct sigqueue *sigqueue_alloc(void)
1647{
1648	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
1649
1650	if (q)
1651		q->flags |= SIGQUEUE_PREALLOC;
1652
1653	return q;
1654}
1655
1656void sigqueue_free(struct sigqueue *q)
1657{
1658	unsigned long flags;
1659	spinlock_t *lock = &current->sighand->siglock;
1660
1661	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1662	/*
1663	 * We must hold ->siglock while testing q->list
1664	 * to serialize with collect_signal() or with
1665	 * __exit_signal()->flush_sigqueue().
1666	 */
1667	spin_lock_irqsave(lock, flags);
1668	q->flags &= ~SIGQUEUE_PREALLOC;
1669	/*
1670	 * If it is queued it will be freed when dequeued,
1671	 * like the "regular" sigqueue.
1672	 */
1673	if (!list_empty(&q->list))
1674		q = NULL;
1675	spin_unlock_irqrestore(lock, flags);
1676
1677	if (q)
1678		__sigqueue_free(q);
1679}
1680
1681int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1682{
1683	int sig = q->info.si_signo;
1684	struct sigpending *pending;
 
1685	unsigned long flags;
1686	int ret, result;
1687
1688	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1689
1690	ret = -1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1691	if (!likely(lock_task_sighand(t, &flags)))
1692		goto ret;
1693
1694	ret = 1; /* the signal is ignored */
1695	result = TRACE_SIGNAL_IGNORED;
1696	if (!prepare_signal(sig, t, false))
1697		goto out;
1698
1699	ret = 0;
1700	if (unlikely(!list_empty(&q->list))) {
1701		/*
1702		 * If an SI_TIMER entry is already queue just increment
1703		 * the overrun count.
1704		 */
1705		BUG_ON(q->info.si_code != SI_TIMER);
1706		q->info.si_overrun++;
1707		result = TRACE_SIGNAL_ALREADY_PENDING;
1708		goto out;
1709	}
1710	q->info.si_overrun = 0;
1711
1712	signalfd_notify(t, sig);
1713	pending = group ? &t->signal->shared_pending : &t->pending;
1714	list_add_tail(&q->list, &pending->list);
1715	sigaddset(&pending->signal, sig);
1716	complete_signal(sig, t, group);
1717	result = TRACE_SIGNAL_DELIVERED;
1718out:
1719	trace_signal_generate(sig, &q->info, t, group, result);
1720	unlock_task_sighand(t, &flags);
1721ret:
 
1722	return ret;
1723}
1724
 
 
 
 
 
 
 
 
 
 
1725/*
1726 * Let a parent know about the death of a child.
1727 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1728 *
1729 * Returns true if our parent ignored us and so we've switched to
1730 * self-reaping.
1731 */
1732bool do_notify_parent(struct task_struct *tsk, int sig)
1733{
1734	struct siginfo info;
1735	unsigned long flags;
1736	struct sighand_struct *psig;
1737	bool autoreap = false;
1738	u64 utime, stime;
1739
1740	BUG_ON(sig == -1);
1741
1742 	/* do_notify_parent_cldstop should have been called instead.  */
1743 	BUG_ON(task_is_stopped_or_traced(tsk));
1744
1745	BUG_ON(!tsk->ptrace &&
1746	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
 
 
 
 
 
 
1747
1748	if (sig != SIGCHLD) {
1749		/*
1750		 * This is only possible if parent == real_parent.
1751		 * Check if it has changed security domain.
1752		 */
1753		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
1754			sig = SIGCHLD;
1755	}
1756
1757	clear_siginfo(&info);
1758	info.si_signo = sig;
1759	info.si_errno = 0;
1760	/*
1761	 * We are under tasklist_lock here so our parent is tied to
1762	 * us and cannot change.
1763	 *
1764	 * task_active_pid_ns will always return the same pid namespace
1765	 * until a task passes through release_task.
1766	 *
1767	 * write_lock() currently calls preempt_disable() which is the
1768	 * same as rcu_read_lock(), but according to Oleg, this is not
1769	 * correct to rely on this
1770	 */
1771	rcu_read_lock();
1772	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1773	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
1774				       task_uid(tsk));
1775	rcu_read_unlock();
1776
1777	task_cputime(tsk, &utime, &stime);
1778	info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
1779	info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
1780
1781	info.si_status = tsk->exit_code & 0x7f;
1782	if (tsk->exit_code & 0x80)
1783		info.si_code = CLD_DUMPED;
1784	else if (tsk->exit_code & 0x7f)
1785		info.si_code = CLD_KILLED;
1786	else {
1787		info.si_code = CLD_EXITED;
1788		info.si_status = tsk->exit_code >> 8;
1789	}
1790
1791	psig = tsk->parent->sighand;
1792	spin_lock_irqsave(&psig->siglock, flags);
1793	if (!tsk->ptrace && sig == SIGCHLD &&
1794	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1795	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1796		/*
1797		 * We are exiting and our parent doesn't care.  POSIX.1
1798		 * defines special semantics for setting SIGCHLD to SIG_IGN
1799		 * or setting the SA_NOCLDWAIT flag: we should be reaped
1800		 * automatically and not left for our parent's wait4 call.
1801		 * Rather than having the parent do it as a magic kind of
1802		 * signal handler, we just set this to tell do_exit that we
1803		 * can be cleaned up without becoming a zombie.  Note that
1804		 * we still call __wake_up_parent in this case, because a
1805		 * blocked sys_wait4 might now return -ECHILD.
1806		 *
1807		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1808		 * is implementation-defined: we do (if you don't want
1809		 * it, just use SIG_IGN instead).
1810		 */
1811		autoreap = true;
1812		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1813			sig = 0;
1814	}
 
 
 
 
1815	if (valid_signal(sig) && sig)
1816		__group_send_sig_info(sig, &info, tsk->parent);
1817	__wake_up_parent(tsk, tsk->parent);
1818	spin_unlock_irqrestore(&psig->siglock, flags);
1819
1820	return autoreap;
1821}
1822
1823/**
1824 * do_notify_parent_cldstop - notify parent of stopped/continued state change
1825 * @tsk: task reporting the state change
1826 * @for_ptracer: the notification is for ptracer
1827 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
1828 *
1829 * Notify @tsk's parent that the stopped/continued state has changed.  If
1830 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
1831 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
1832 *
1833 * CONTEXT:
1834 * Must be called with tasklist_lock at least read locked.
1835 */
1836static void do_notify_parent_cldstop(struct task_struct *tsk,
1837				     bool for_ptracer, int why)
1838{
1839	struct siginfo info;
1840	unsigned long flags;
1841	struct task_struct *parent;
1842	struct sighand_struct *sighand;
1843	u64 utime, stime;
1844
1845	if (for_ptracer) {
1846		parent = tsk->parent;
1847	} else {
1848		tsk = tsk->group_leader;
1849		parent = tsk->real_parent;
1850	}
1851
1852	clear_siginfo(&info);
1853	info.si_signo = SIGCHLD;
1854	info.si_errno = 0;
1855	/*
1856	 * see comment in do_notify_parent() about the following 4 lines
1857	 */
1858	rcu_read_lock();
1859	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1860	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1861	rcu_read_unlock();
1862
1863	task_cputime(tsk, &utime, &stime);
1864	info.si_utime = nsec_to_clock_t(utime);
1865	info.si_stime = nsec_to_clock_t(stime);
1866
1867 	info.si_code = why;
1868 	switch (why) {
1869 	case CLD_CONTINUED:
1870 		info.si_status = SIGCONT;
1871 		break;
1872 	case CLD_STOPPED:
1873 		info.si_status = tsk->signal->group_exit_code & 0x7f;
1874 		break;
1875 	case CLD_TRAPPED:
1876 		info.si_status = tsk->exit_code & 0x7f;
1877 		break;
1878 	default:
1879 		BUG();
1880 	}
1881
1882	sighand = parent->sighand;
1883	spin_lock_irqsave(&sighand->siglock, flags);
1884	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1885	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1886		__group_send_sig_info(SIGCHLD, &info, parent);
1887	/*
1888	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1889	 */
1890	__wake_up_parent(tsk, parent);
1891	spin_unlock_irqrestore(&sighand->siglock, flags);
1892}
1893
1894static inline int may_ptrace_stop(void)
1895{
1896	if (!likely(current->ptrace))
1897		return 0;
1898	/*
1899	 * Are we in the middle of do_coredump?
1900	 * If so and our tracer is also part of the coredump stopping
1901	 * is a deadlock situation, and pointless because our tracer
1902	 * is dead so don't allow us to stop.
1903	 * If SIGKILL was already sent before the caller unlocked
1904	 * ->siglock we must see ->core_state != NULL. Otherwise it
1905	 * is safe to enter schedule().
1906	 *
1907	 * This is almost outdated, a task with the pending SIGKILL can't
1908	 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
1909	 * after SIGKILL was already dequeued.
1910	 */
1911	if (unlikely(current->mm->core_state) &&
1912	    unlikely(current->mm == current->parent->mm))
1913		return 0;
1914
1915	return 1;
1916}
1917
1918/*
1919 * Return non-zero if there is a SIGKILL that should be waking us up.
1920 * Called with the siglock held.
1921 */
1922static int sigkill_pending(struct task_struct *tsk)
1923{
1924	return	sigismember(&tsk->pending.signal, SIGKILL) ||
1925		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
1926}
1927
1928/*
1929 * This must be called with current->sighand->siglock held.
1930 *
1931 * This should be the path for all ptrace stops.
1932 * We always set current->last_siginfo while stopped here.
1933 * That makes it a way to test a stopped process for
1934 * being ptrace-stopped vs being job-control-stopped.
1935 *
1936 * If we actually decide not to stop at all because the tracer
1937 * is gone, we keep current->exit_code unless clear_code.
 
1938 */
1939static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
 
1940	__releases(&current->sighand->siglock)
1941	__acquires(&current->sighand->siglock)
1942{
1943	bool gstop_done = false;
1944
1945	if (arch_ptrace_stop_needed(exit_code, info)) {
1946		/*
1947		 * The arch code has something special to do before a
1948		 * ptrace stop.  This is allowed to block, e.g. for faults
1949		 * on user stack pages.  We can't keep the siglock while
1950		 * calling arch_ptrace_stop, so we must release it now.
1951		 * To preserve proper semantics, we must do this before
1952		 * any signal bookkeeping like checking group_stop_count.
1953		 * Meanwhile, a SIGKILL could come in before we retake the
1954		 * siglock.  That must prevent us from sleeping in TASK_TRACED.
1955		 * So after regaining the lock, we must check for SIGKILL.
1956		 */
1957		spin_unlock_irq(&current->sighand->siglock);
1958		arch_ptrace_stop(exit_code, info);
1959		spin_lock_irq(&current->sighand->siglock);
1960		if (sigkill_pending(current))
1961			return;
1962	}
1963
 
 
 
 
 
 
 
 
 
1964	set_special_state(TASK_TRACED);
 
1965
1966	/*
1967	 * We're committing to trapping.  TRACED should be visible before
1968	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
1969	 * Also, transition to TRACED and updates to ->jobctl should be
1970	 * atomic with respect to siglock and should be done after the arch
1971	 * hook as siglock is released and regrabbed across it.
1972	 *
1973	 *     TRACER				    TRACEE
1974	 *
1975	 *     ptrace_attach()
1976	 * [L]   wait_on_bit(JOBCTL_TRAPPING)	[S] set_special_state(TRACED)
1977	 *     do_wait()
1978	 *       set_current_state()                smp_wmb();
1979	 *       ptrace_do_wait()
1980	 *         wait_task_stopped()
1981	 *           task_stopped_code()
1982	 * [L]         task_is_traced()		[S] task_clear_jobctl_trapping();
1983	 */
1984	smp_wmb();
1985
 
1986	current->last_siginfo = info;
1987	current->exit_code = exit_code;
1988
1989	/*
1990	 * If @why is CLD_STOPPED, we're trapping to participate in a group
1991	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1992	 * across siglock relocks since INTERRUPT was scheduled, PENDING
1993	 * could be clear now.  We act as if SIGCONT is received after
1994	 * TASK_TRACED is entered - ignore it.
1995	 */
1996	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1997		gstop_done = task_participate_group_stop(current);
1998
1999	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2000	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2001	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2002		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2003
2004	/* entering a trap, clear TRAPPING */
2005	task_clear_jobctl_trapping(current);
2006
2007	spin_unlock_irq(&current->sighand->siglock);
2008	read_lock(&tasklist_lock);
2009	if (may_ptrace_stop()) {
2010		/*
2011		 * Notify parents of the stop.
2012		 *
2013		 * While ptraced, there are two parents - the ptracer and
2014		 * the real_parent of the group_leader.  The ptracer should
2015		 * know about every stop while the real parent is only
2016		 * interested in the completion of group stop.  The states
2017		 * for the two don't interact with each other.  Notify
2018		 * separately unless they're gonna be duplicates.
2019		 */
2020		do_notify_parent_cldstop(current, true, why);
2021		if (gstop_done && ptrace_reparented(current))
2022			do_notify_parent_cldstop(current, false, why);
2023
2024		/*
2025		 * Don't want to allow preemption here, because
2026		 * sys_ptrace() needs this task to be inactive.
2027		 *
2028		 * XXX: implement read_unlock_no_resched().
2029		 */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2030		preempt_disable();
2031		read_unlock(&tasklist_lock);
 
 
2032		preempt_enable_no_resched();
2033		freezable_schedule();
2034	} else {
2035		/*
2036		 * By the time we got the lock, our tracer went away.
2037		 * Don't drop the lock yet, another tracer may come.
2038		 *
2039		 * If @gstop_done, the ptracer went away between group stop
2040		 * completion and here.  During detach, it would have set
2041		 * JOBCTL_STOP_PENDING on us and we'll re-enter
2042		 * TASK_STOPPED in do_signal_stop() on return, so notifying
2043		 * the real parent of the group stop completion is enough.
2044		 */
2045		if (gstop_done)
2046			do_notify_parent_cldstop(current, false, why);
2047
2048		/* tasklist protects us from ptrace_freeze_traced() */
2049		__set_current_state(TASK_RUNNING);
2050		if (clear_code)
2051			current->exit_code = 0;
2052		read_unlock(&tasklist_lock);
2053	}
2054
2055	/*
2056	 * We are back.  Now reacquire the siglock before touching
2057	 * last_siginfo, so that we are sure to have synchronized with
2058	 * any signal-sending on another CPU that wants to examine it.
2059	 */
2060	spin_lock_irq(&current->sighand->siglock);
 
2061	current->last_siginfo = NULL;
 
 
2062
2063	/* LISTENING can be set only during STOP traps, clear it */
2064	current->jobctl &= ~JOBCTL_LISTENING;
2065
2066	/*
2067	 * Queued signals ignored us while we were stopped for tracing.
2068	 * So check for any that we should take before resuming user mode.
2069	 * This sets TIF_SIGPENDING, but never clears it.
2070	 */
2071	recalc_sigpending_tsk(current);
 
2072}
2073
2074static void ptrace_do_notify(int signr, int exit_code, int why)
2075{
2076	siginfo_t info;
2077
2078	clear_siginfo(&info);
2079	info.si_signo = signr;
2080	info.si_code = exit_code;
2081	info.si_pid = task_pid_vnr(current);
2082	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2083
2084	/* Let the debugger run.  */
2085	ptrace_stop(exit_code, why, 1, &info);
2086}
2087
2088void ptrace_notify(int exit_code)
2089{
 
 
2090	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2091	if (unlikely(current->task_works))
2092		task_work_run();
2093
2094	spin_lock_irq(&current->sighand->siglock);
2095	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
2096	spin_unlock_irq(&current->sighand->siglock);
 
2097}
2098
2099/**
2100 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2101 * @signr: signr causing group stop if initiating
2102 *
2103 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2104 * and participate in it.  If already set, participate in the existing
2105 * group stop.  If participated in a group stop (and thus slept), %true is
2106 * returned with siglock released.
2107 *
2108 * If ptraced, this function doesn't handle stop itself.  Instead,
2109 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2110 * untouched.  The caller must ensure that INTERRUPT trap handling takes
2111 * places afterwards.
2112 *
2113 * CONTEXT:
2114 * Must be called with @current->sighand->siglock held, which is released
2115 * on %true return.
2116 *
2117 * RETURNS:
2118 * %false if group stop is already cancelled or ptrace trap is scheduled.
2119 * %true if participated in group stop.
2120 */
2121static bool do_signal_stop(int signr)
2122	__releases(&current->sighand->siglock)
2123{
2124	struct signal_struct *sig = current->signal;
2125
2126	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2127		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2128		struct task_struct *t;
2129
2130		/* signr will be recorded in task->jobctl for retries */
2131		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2132
2133		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2134		    unlikely(signal_group_exit(sig)))
 
2135			return false;
2136		/*
2137		 * There is no group stop already in progress.  We must
2138		 * initiate one now.
2139		 *
2140		 * While ptraced, a task may be resumed while group stop is
2141		 * still in effect and then receive a stop signal and
2142		 * initiate another group stop.  This deviates from the
2143		 * usual behavior as two consecutive stop signals can't
2144		 * cause two group stops when !ptraced.  That is why we
2145		 * also check !task_is_stopped(t) below.
2146		 *
2147		 * The condition can be distinguished by testing whether
2148		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
2149		 * group_exit_code in such case.
2150		 *
2151		 * This is not necessary for SIGNAL_STOP_CONTINUED because
2152		 * an intervening stop signal is required to cause two
2153		 * continued events regardless of ptrace.
2154		 */
2155		if (!(sig->flags & SIGNAL_STOP_STOPPED))
2156			sig->group_exit_code = signr;
2157
2158		sig->group_stop_count = 0;
2159
2160		if (task_set_jobctl_pending(current, signr | gstop))
2161			sig->group_stop_count++;
2162
2163		t = current;
2164		while_each_thread(current, t) {
2165			/*
2166			 * Setting state to TASK_STOPPED for a group
2167			 * stop is always done with the siglock held,
2168			 * so this check has no races.
2169			 */
2170			if (!task_is_stopped(t) &&
2171			    task_set_jobctl_pending(t, signr | gstop)) {
2172				sig->group_stop_count++;
2173				if (likely(!(t->ptrace & PT_SEIZED)))
2174					signal_wake_up(t, 0);
2175				else
2176					ptrace_trap_notify(t);
2177			}
2178		}
2179	}
2180
2181	if (likely(!current->ptrace)) {
2182		int notify = 0;
2183
2184		/*
2185		 * If there are no other threads in the group, or if there
2186		 * is a group stop in progress and we are the last to stop,
2187		 * report to the parent.
2188		 */
2189		if (task_participate_group_stop(current))
2190			notify = CLD_STOPPED;
2191
 
2192		set_special_state(TASK_STOPPED);
2193		spin_unlock_irq(&current->sighand->siglock);
2194
2195		/*
2196		 * Notify the parent of the group stop completion.  Because
2197		 * we're not holding either the siglock or tasklist_lock
2198		 * here, ptracer may attach inbetween; however, this is for
2199		 * group stop and should always be delivered to the real
2200		 * parent of the group leader.  The new ptracer will get
2201		 * its notification when this task transitions into
2202		 * TASK_TRACED.
2203		 */
2204		if (notify) {
2205			read_lock(&tasklist_lock);
2206			do_notify_parent_cldstop(current, false, notify);
2207			read_unlock(&tasklist_lock);
2208		}
2209
2210		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2211		freezable_schedule();
 
2212		return true;
2213	} else {
2214		/*
2215		 * While ptraced, group stop is handled by STOP trap.
2216		 * Schedule it and let the caller deal with it.
2217		 */
2218		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2219		return false;
2220	}
2221}
2222
2223/**
2224 * do_jobctl_trap - take care of ptrace jobctl traps
2225 *
2226 * When PT_SEIZED, it's used for both group stop and explicit
2227 * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
2228 * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
2229 * the stop signal; otherwise, %SIGTRAP.
2230 *
2231 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2232 * number as exit_code and no siginfo.
2233 *
2234 * CONTEXT:
2235 * Must be called with @current->sighand->siglock held, which may be
2236 * released and re-acquired before returning with intervening sleep.
2237 */
2238static void do_jobctl_trap(void)
2239{
2240	struct signal_struct *signal = current->signal;
2241	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2242
2243	if (current->ptrace & PT_SEIZED) {
2244		if (!signal->group_stop_count &&
2245		    !(signal->flags & SIGNAL_STOP_STOPPED))
2246			signr = SIGTRAP;
2247		WARN_ON_ONCE(!signr);
2248		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2249				 CLD_STOPPED);
2250	} else {
2251		WARN_ON_ONCE(!signr);
2252		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
2253		current->exit_code = 0;
2254	}
2255}
2256
2257static int ptrace_signal(int signr, siginfo_t *info)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2258{
2259	/*
2260	 * We do not check sig_kernel_stop(signr) but set this marker
2261	 * unconditionally because we do not know whether debugger will
2262	 * change signr. This flag has no meaning unless we are going
2263	 * to stop after return from ptrace_stop(). In this case it will
2264	 * be checked in do_signal_stop(), we should only stop if it was
2265	 * not cleared by SIGCONT while we were sleeping. See also the
2266	 * comment in dequeue_signal().
2267	 */
2268	current->jobctl |= JOBCTL_STOP_DEQUEUED;
2269	ptrace_stop(signr, CLD_TRAPPED, 0, info);
2270
2271	/* We're back.  Did the debugger cancel the sig?  */
2272	signr = current->exit_code;
2273	if (signr == 0)
2274		return signr;
2275
2276	current->exit_code = 0;
2277
2278	/*
2279	 * Update the siginfo structure if the signal has
2280	 * changed.  If the debugger wanted something
2281	 * specific in the siginfo structure then it should
2282	 * have updated *info via PTRACE_SETSIGINFO.
2283	 */
2284	if (signr != info->si_signo) {
2285		clear_siginfo(info);
2286		info->si_signo = signr;
2287		info->si_errno = 0;
2288		info->si_code = SI_USER;
2289		rcu_read_lock();
2290		info->si_pid = task_pid_vnr(current->parent);
2291		info->si_uid = from_kuid_munged(current_user_ns(),
2292						task_uid(current->parent));
2293		rcu_read_unlock();
2294	}
2295
2296	/* If the (new) signal is now blocked, requeue it.  */
2297	if (sigismember(&current->blocked, signr)) {
2298		specific_send_sig_info(signr, info, current);
 
2299		signr = 0;
2300	}
2301
2302	return signr;
2303}
2304
2305int get_signal(struct ksignal *ksig)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2306{
2307	struct sighand_struct *sighand = current->sighand;
2308	struct signal_struct *signal = current->signal;
2309	int signr;
2310
2311	if (unlikely(current->task_works))
 
2312		task_work_run();
2313
 
 
 
2314	if (unlikely(uprobe_deny_signal()))
2315		return 0;
2316
2317	/*
2318	 * Do this once, we can't return to user-mode if freezing() == T.
2319	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2320	 * thus do not need another check after return.
2321	 */
2322	try_to_freeze();
2323
2324relock:
2325	spin_lock_irq(&sighand->siglock);
 
2326	/*
2327	 * Every stopped thread goes here after wakeup. Check to see if
2328	 * we should notify the parent, prepare_signal(SIGCONT) encodes
2329	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2330	 */
2331	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2332		int why;
2333
2334		if (signal->flags & SIGNAL_CLD_CONTINUED)
2335			why = CLD_CONTINUED;
2336		else
2337			why = CLD_STOPPED;
2338
2339		signal->flags &= ~SIGNAL_CLD_MASK;
2340
2341		spin_unlock_irq(&sighand->siglock);
2342
2343		/*
2344		 * Notify the parent that we're continuing.  This event is
2345		 * always per-process and doesn't make whole lot of sense
2346		 * for ptracers, who shouldn't consume the state via
2347		 * wait(2) either, but, for backward compatibility, notify
2348		 * the ptracer of the group leader too unless it's gonna be
2349		 * a duplicate.
2350		 */
2351		read_lock(&tasklist_lock);
2352		do_notify_parent_cldstop(current, false, why);
2353
2354		if (ptrace_reparented(current->group_leader))
2355			do_notify_parent_cldstop(current->group_leader,
2356						true, why);
2357		read_unlock(&tasklist_lock);
2358
2359		goto relock;
2360	}
2361
2362	for (;;) {
2363		struct k_sigaction *ka;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2364
2365		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2366		    do_signal_stop(0))
2367			goto relock;
2368
2369		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
2370			do_jobctl_trap();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2371			spin_unlock_irq(&sighand->siglock);
 
2372			goto relock;
2373		}
2374
2375		signr = dequeue_signal(current, &current->blocked, &ksig->info);
 
 
 
 
 
 
 
 
 
 
2376
2377		if (!signr)
2378			break; /* will return 0 */
2379
2380		if (unlikely(current->ptrace) && signr != SIGKILL) {
2381			signr = ptrace_signal(signr, &ksig->info);
 
2382			if (!signr)
2383				continue;
2384		}
2385
2386		ka = &sighand->action[signr-1];
2387
2388		/* Trace actually delivered signals. */
2389		trace_signal_deliver(signr, &ksig->info, ka);
2390
2391		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
2392			continue;
2393		if (ka->sa.sa_handler != SIG_DFL) {
2394			/* Run the handler.  */
2395			ksig->ka = *ka;
2396
2397			if (ka->sa.sa_flags & SA_ONESHOT)
2398				ka->sa.sa_handler = SIG_DFL;
2399
2400			break; /* will return non-zero "signr" value */
2401		}
2402
2403		/*
2404		 * Now we are doing the default action for this signal.
2405		 */
2406		if (sig_kernel_ignore(signr)) /* Default is nothing. */
2407			continue;
2408
2409		/*
2410		 * Global init gets no signals it doesn't want.
2411		 * Container-init gets no signals it doesn't want from same
2412		 * container.
2413		 *
2414		 * Note that if global/container-init sees a sig_kernel_only()
2415		 * signal here, the signal must have been generated internally
2416		 * or must have come from an ancestor namespace. In either
2417		 * case, the signal cannot be dropped.
2418		 */
2419		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2420				!sig_kernel_only(signr))
2421			continue;
2422
2423		if (sig_kernel_stop(signr)) {
2424			/*
2425			 * The default action is to stop all threads in
2426			 * the thread group.  The job control signals
2427			 * do nothing in an orphaned pgrp, but SIGSTOP
2428			 * always works.  Note that siglock needs to be
2429			 * dropped during the call to is_orphaned_pgrp()
2430			 * because of lock ordering with tasklist_lock.
2431			 * This allows an intervening SIGCONT to be posted.
2432			 * We need to check for that and bail out if necessary.
2433			 */
2434			if (signr != SIGSTOP) {
2435				spin_unlock_irq(&sighand->siglock);
2436
2437				/* signals can be posted during this window */
2438
2439				if (is_current_pgrp_orphaned())
2440					goto relock;
2441
2442				spin_lock_irq(&sighand->siglock);
2443			}
2444
2445			if (likely(do_signal_stop(ksig->info.si_signo))) {
2446				/* It released the siglock.  */
2447				goto relock;
2448			}
2449
2450			/*
2451			 * We didn't actually stop, due to a race
2452			 * with SIGCONT or something like that.
2453			 */
2454			continue;
2455		}
2456
 
2457		spin_unlock_irq(&sighand->siglock);
 
 
2458
2459		/*
2460		 * Anything else is fatal, maybe with a core dump.
2461		 */
2462		current->flags |= PF_SIGNALED;
2463
2464		if (sig_kernel_coredump(signr)) {
2465			if (print_fatal_signals)
2466				print_fatal_signal(ksig->info.si_signo);
2467			proc_coredump_connector(current);
2468			/*
2469			 * If it was able to dump core, this kills all
2470			 * other threads in the group and synchronizes with
2471			 * their demise.  If we lost the race with another
2472			 * thread getting here, it set group_exit_code
2473			 * first and our do_group_exit call below will use
2474			 * that value and ignore the one we pass it.
2475			 */
2476			do_coredump(&ksig->info);
2477		}
2478
2479		/*
 
 
 
 
 
 
 
 
 
2480		 * Death signals, no core dump.
2481		 */
2482		do_group_exit(ksig->info.si_signo);
2483		/* NOTREACHED */
2484	}
2485	spin_unlock_irq(&sighand->siglock);
2486
2487	ksig->sig = signr;
2488	return ksig->sig > 0;
 
 
 
 
2489}
2490
2491/**
2492 * signal_delivered - 
2493 * @ksig:		kernel signal struct
2494 * @stepping:		nonzero if debugger single-step or block-step in use
2495 *
2496 * This function should be called when a signal has successfully been
2497 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2498 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
2499 * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2500 */
2501static void signal_delivered(struct ksignal *ksig, int stepping)
2502{
2503	sigset_t blocked;
2504
2505	/* A signal was successfully delivered, and the
2506	   saved sigmask was stored on the signal frame,
2507	   and will be restored by sigreturn.  So we can
2508	   simply clear the restore sigmask flag.  */
2509	clear_restore_sigmask();
2510
2511	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
2512	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2513		sigaddset(&blocked, ksig->sig);
2514	set_current_blocked(&blocked);
2515	tracehook_signal_handler(stepping);
 
 
 
2516}
2517
2518void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2519{
2520	if (failed)
2521		force_sigsegv(ksig->sig, current);
2522	else
2523		signal_delivered(ksig, stepping);
2524}
2525
2526/*
2527 * It could be that complete_signal() picked us to notify about the
2528 * group-wide signal. Other threads should be notified now to take
2529 * the shared signals in @which since we will not.
2530 */
2531static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2532{
2533	sigset_t retarget;
2534	struct task_struct *t;
2535
2536	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2537	if (sigisemptyset(&retarget))
2538		return;
2539
2540	t = tsk;
2541	while_each_thread(tsk, t) {
2542		if (t->flags & PF_EXITING)
2543			continue;
2544
2545		if (!has_pending_signals(&retarget, &t->blocked))
2546			continue;
2547		/* Remove the signals this thread can handle. */
2548		sigandsets(&retarget, &retarget, &t->blocked);
2549
2550		if (!signal_pending(t))
2551			signal_wake_up(t, 0);
2552
2553		if (sigisemptyset(&retarget))
2554			break;
2555	}
2556}
2557
2558void exit_signals(struct task_struct *tsk)
2559{
2560	int group_stop = 0;
2561	sigset_t unblocked;
2562
2563	/*
2564	 * @tsk is about to have PF_EXITING set - lock out users which
2565	 * expect stable threadgroup.
2566	 */
2567	cgroup_threadgroup_change_begin(tsk);
2568
2569	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
 
2570		tsk->flags |= PF_EXITING;
2571		cgroup_threadgroup_change_end(tsk);
2572		return;
2573	}
2574
2575	spin_lock_irq(&tsk->sighand->siglock);
2576	/*
2577	 * From now this task is not visible for group-wide signals,
2578	 * see wants_signal(), do_signal_stop().
2579	 */
 
2580	tsk->flags |= PF_EXITING;
2581
2582	cgroup_threadgroup_change_end(tsk);
2583
2584	if (!signal_pending(tsk))
2585		goto out;
2586
2587	unblocked = tsk->blocked;
2588	signotset(&unblocked);
2589	retarget_shared_pending(tsk, &unblocked);
2590
2591	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2592	    task_participate_group_stop(tsk))
2593		group_stop = CLD_STOPPED;
2594out:
2595	spin_unlock_irq(&tsk->sighand->siglock);
2596
2597	/*
2598	 * If group stop has completed, deliver the notification.  This
2599	 * should always go to the real parent of the group leader.
2600	 */
2601	if (unlikely(group_stop)) {
2602		read_lock(&tasklist_lock);
2603		do_notify_parent_cldstop(tsk, false, group_stop);
2604		read_unlock(&tasklist_lock);
2605	}
2606}
2607
2608EXPORT_SYMBOL(recalc_sigpending);
2609EXPORT_SYMBOL_GPL(dequeue_signal);
2610EXPORT_SYMBOL(flush_signals);
2611EXPORT_SYMBOL(force_sig);
2612EXPORT_SYMBOL(send_sig);
2613EXPORT_SYMBOL(send_sig_info);
2614EXPORT_SYMBOL(sigprocmask);
2615
2616/*
2617 * System call entry points.
2618 */
2619
2620/**
2621 *  sys_restart_syscall - restart a system call
2622 */
2623SYSCALL_DEFINE0(restart_syscall)
2624{
2625	struct restart_block *restart = &current->restart_block;
2626	return restart->fn(restart);
2627}
2628
2629long do_no_restart_syscall(struct restart_block *param)
2630{
2631	return -EINTR;
2632}
2633
2634static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
2635{
2636	if (signal_pending(tsk) && !thread_group_empty(tsk)) {
2637		sigset_t newblocked;
2638		/* A set of now blocked but previously unblocked signals. */
2639		sigandnsets(&newblocked, newset, &current->blocked);
2640		retarget_shared_pending(tsk, &newblocked);
2641	}
2642	tsk->blocked = *newset;
2643	recalc_sigpending();
2644}
2645
2646/**
2647 * set_current_blocked - change current->blocked mask
2648 * @newset: new mask
2649 *
2650 * It is wrong to change ->blocked directly, this helper should be used
2651 * to ensure the process can't miss a shared signal we are going to block.
2652 */
2653void set_current_blocked(sigset_t *newset)
2654{
2655	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2656	__set_current_blocked(newset);
2657}
2658
2659void __set_current_blocked(const sigset_t *newset)
2660{
2661	struct task_struct *tsk = current;
2662
2663	/*
2664	 * In case the signal mask hasn't changed, there is nothing we need
2665	 * to do. The current->blocked shouldn't be modified by other task.
2666	 */
2667	if (sigequalsets(&tsk->blocked, newset))
2668		return;
2669
2670	spin_lock_irq(&tsk->sighand->siglock);
2671	__set_task_blocked(tsk, newset);
2672	spin_unlock_irq(&tsk->sighand->siglock);
2673}
2674
2675/*
2676 * This is also useful for kernel threads that want to temporarily
2677 * (or permanently) block certain signals.
2678 *
2679 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2680 * interface happily blocks "unblockable" signals like SIGKILL
2681 * and friends.
2682 */
2683int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2684{
2685	struct task_struct *tsk = current;
2686	sigset_t newset;
2687
2688	/* Lockless, only current can change ->blocked, never from irq */
2689	if (oldset)
2690		*oldset = tsk->blocked;
2691
2692	switch (how) {
2693	case SIG_BLOCK:
2694		sigorsets(&newset, &tsk->blocked, set);
2695		break;
2696	case SIG_UNBLOCK:
2697		sigandnsets(&newset, &tsk->blocked, set);
2698		break;
2699	case SIG_SETMASK:
2700		newset = *set;
2701		break;
2702	default:
2703		return -EINVAL;
2704	}
2705
2706	__set_current_blocked(&newset);
2707	return 0;
2708}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2709
2710/**
2711 *  sys_rt_sigprocmask - change the list of currently blocked signals
2712 *  @how: whether to add, remove, or set signals
2713 *  @nset: stores pending signals
2714 *  @oset: previous value of signal mask if non-null
2715 *  @sigsetsize: size of sigset_t type
2716 */
2717SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2718		sigset_t __user *, oset, size_t, sigsetsize)
2719{
2720	sigset_t old_set, new_set;
2721	int error;
2722
2723	/* XXX: Don't preclude handling different sized sigset_t's.  */
2724	if (sigsetsize != sizeof(sigset_t))
2725		return -EINVAL;
2726
2727	old_set = current->blocked;
2728
2729	if (nset) {
2730		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
2731			return -EFAULT;
2732		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2733
2734		error = sigprocmask(how, &new_set, NULL);
2735		if (error)
2736			return error;
2737	}
2738
2739	if (oset) {
2740		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
2741			return -EFAULT;
2742	}
2743
2744	return 0;
2745}
2746
2747#ifdef CONFIG_COMPAT
2748COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
2749		compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
2750{
2751	sigset_t old_set = current->blocked;
2752
2753	/* XXX: Don't preclude handling different sized sigset_t's.  */
2754	if (sigsetsize != sizeof(sigset_t))
2755		return -EINVAL;
2756
2757	if (nset) {
2758		sigset_t new_set;
2759		int error;
2760		if (get_compat_sigset(&new_set, nset))
2761			return -EFAULT;
2762		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2763
2764		error = sigprocmask(how, &new_set, NULL);
2765		if (error)
2766			return error;
2767	}
2768	return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
2769}
2770#endif
2771
2772static int do_sigpending(sigset_t *set)
2773{
2774	spin_lock_irq(&current->sighand->siglock);
2775	sigorsets(set, &current->pending.signal,
2776		  &current->signal->shared_pending.signal);
2777	spin_unlock_irq(&current->sighand->siglock);
2778
2779	/* Outside the lock because only this thread touches it.  */
2780	sigandsets(set, &current->blocked, set);
2781	return 0;
2782}
2783
2784/**
2785 *  sys_rt_sigpending - examine a pending signal that has been raised
2786 *			while blocked
2787 *  @uset: stores pending signals
2788 *  @sigsetsize: size of sigset_t type or larger
2789 */
2790SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
2791{
2792	sigset_t set;
2793	int err;
2794
2795	if (sigsetsize > sizeof(*uset))
2796		return -EINVAL;
2797
2798	err = do_sigpending(&set);
2799	if (!err && copy_to_user(uset, &set, sigsetsize))
2800		err = -EFAULT;
2801	return err;
 
 
2802}
2803
2804#ifdef CONFIG_COMPAT
2805COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
2806		compat_size_t, sigsetsize)
2807{
2808	sigset_t set;
2809	int err;
2810
2811	if (sigsetsize > sizeof(*uset))
2812		return -EINVAL;
2813
2814	err = do_sigpending(&set);
2815	if (!err)
2816		err = put_compat_sigset(uset, &set, sigsetsize);
2817	return err;
2818}
2819#endif
2820
2821enum siginfo_layout siginfo_layout(int sig, int si_code)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2822{
2823	enum siginfo_layout layout = SIL_KILL;
2824	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
2825		static const struct {
2826			unsigned char limit, layout;
2827		} filter[] = {
2828			[SIGILL]  = { NSIGILL,  SIL_FAULT },
2829			[SIGFPE]  = { NSIGFPE,  SIL_FAULT },
2830			[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
2831			[SIGBUS]  = { NSIGBUS,  SIL_FAULT },
2832			[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
2833#if defined(SIGEMT) && defined(NSIGEMT)
2834			[SIGEMT]  = { NSIGEMT,  SIL_FAULT },
2835#endif
2836			[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
2837			[SIGPOLL] = { NSIGPOLL, SIL_POLL },
2838			[SIGSYS]  = { NSIGSYS,  SIL_SYS },
2839		};
2840		if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit))
2841			layout = filter[sig].layout;
 
 
 
 
 
 
2842		else if (si_code <= NSIGPOLL)
2843			layout = SIL_POLL;
2844	} else {
2845		if (si_code == SI_TIMER)
2846			layout = SIL_TIMER;
2847		else if (si_code == SI_SIGIO)
2848			layout = SIL_POLL;
2849		else if (si_code < 0)
2850			layout = SIL_RT;
2851		/* Tests to support buggy kernel ABIs */
2852#ifdef TRAP_FIXME
2853		if ((sig == SIGTRAP) && (si_code == TRAP_FIXME))
2854			layout = SIL_FAULT;
2855#endif
2856#ifdef FPE_FIXME
2857		if ((sig == SIGFPE) && (si_code == FPE_FIXME))
2858			layout = SIL_FAULT;
2859#endif
2860	}
2861	return layout;
2862}
2863
2864int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
2865{
2866	int err;
 
2867
2868	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
 
 
 
2869		return -EFAULT;
2870	if (from->si_code < 0)
2871		return __copy_to_user(to, from, sizeof(siginfo_t))
2872			? -EFAULT : 0;
2873	/*
2874	 * If you change siginfo_t structure, please be sure
2875	 * this code is fixed accordingly.
2876	 * Please remember to update the signalfd_copyinfo() function
2877	 * inside fs/signalfd.c too, in case siginfo_t changes.
2878	 * It should never copy any pad contained in the structure
2879	 * to avoid security leaks, but must copy the generic
2880	 * 3 ints plus the relevant union member.
2881	 */
2882	err = __put_user(from->si_signo, &to->si_signo);
2883	err |= __put_user(from->si_errno, &to->si_errno);
2884	err |= __put_user(from->si_code, &to->si_code);
2885	switch (siginfo_layout(from->si_signo, from->si_code)) {
2886	case SIL_KILL:
2887		err |= __put_user(from->si_pid, &to->si_pid);
2888		err |= __put_user(from->si_uid, &to->si_uid);
2889		break;
2890	case SIL_TIMER:
2891		/* Unreached SI_TIMER is negative */
2892		break;
2893	case SIL_POLL:
2894		err |= __put_user(from->si_band, &to->si_band);
2895		err |= __put_user(from->si_fd, &to->si_fd);
2896		break;
2897	case SIL_FAULT:
2898		err |= __put_user(from->si_addr, &to->si_addr);
2899#ifdef __ARCH_SI_TRAPNO
2900		err |= __put_user(from->si_trapno, &to->si_trapno);
2901#endif
2902#ifdef __ia64__
2903		err |= __put_user(from->si_imm, &to->si_imm);
2904		err |= __put_user(from->si_flags, &to->si_flags);
2905		err |= __put_user(from->si_isr, &to->si_isr);
2906#endif
2907		/*
2908		 * Other callers might not initialize the si_lsb field,
2909		 * so check explicitly for the right codes here.
2910		 */
2911#ifdef BUS_MCEERR_AR
2912		if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AR)
2913			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2914#endif
2915#ifdef BUS_MCEERR_AO
2916		if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AO)
2917			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2918#endif
2919#ifdef SEGV_BNDERR
2920		if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
2921			err |= __put_user(from->si_lower, &to->si_lower);
2922			err |= __put_user(from->si_upper, &to->si_upper);
2923		}
2924#endif
2925#ifdef SEGV_PKUERR
2926		if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
2927			err |= __put_user(from->si_pkey, &to->si_pkey);
2928#endif
2929		break;
2930	case SIL_CHLD:
2931		err |= __put_user(from->si_pid, &to->si_pid);
2932		err |= __put_user(from->si_uid, &to->si_uid);
2933		err |= __put_user(from->si_status, &to->si_status);
2934		err |= __put_user(from->si_utime, &to->si_utime);
2935		err |= __put_user(from->si_stime, &to->si_stime);
2936		break;
2937	case SIL_RT:
2938		err |= __put_user(from->si_pid, &to->si_pid);
2939		err |= __put_user(from->si_uid, &to->si_uid);
2940		err |= __put_user(from->si_ptr, &to->si_ptr);
2941		break;
2942	case SIL_SYS:
2943		err |= __put_user(from->si_call_addr, &to->si_call_addr);
2944		err |= __put_user(from->si_syscall, &to->si_syscall);
2945		err |= __put_user(from->si_arch, &to->si_arch);
2946		break;
2947	}
2948	return err;
2949}
2950
2951#ifdef CONFIG_COMPAT
2952int copy_siginfo_to_user32(struct compat_siginfo __user *to,
2953			   const struct siginfo *from)
2954#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
2955{
2956	return __copy_siginfo_to_user32(to, from, in_x32_syscall());
 
 
 
2957}
2958int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
2959			     const struct siginfo *from, bool x32_ABI)
2960#endif
2961{
2962	struct compat_siginfo new;
2963	memset(&new, 0, sizeof(new));
 
 
2964
2965	new.si_signo = from->si_signo;
2966	new.si_errno = from->si_errno;
2967	new.si_code  = from->si_code;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2968	switch(siginfo_layout(from->si_signo, from->si_code)) {
2969	case SIL_KILL:
2970		new.si_pid = from->si_pid;
2971		new.si_uid = from->si_uid;
2972		break;
2973	case SIL_TIMER:
2974		new.si_tid     = from->si_tid;
2975		new.si_overrun = from->si_overrun;
2976		new.si_int     = from->si_int;
2977		break;
2978	case SIL_POLL:
2979		new.si_band = from->si_band;
2980		new.si_fd   = from->si_fd;
2981		break;
2982	case SIL_FAULT:
2983		new.si_addr = ptr_to_compat(from->si_addr);
2984#ifdef __ARCH_SI_TRAPNO
2985		new.si_trapno = from->si_trapno;
2986#endif
2987#ifdef BUS_MCEERR_AR
2988		if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AR))
2989			new.si_addr_lsb = from->si_addr_lsb;
2990#endif
2991#ifdef BUS_MCEERR_AO
2992		if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AO))
2993			new.si_addr_lsb = from->si_addr_lsb;
2994#endif
2995#ifdef SEGV_BNDERR
2996		if ((from->si_signo == SIGSEGV) &&
2997		    (from->si_code == SEGV_BNDERR)) {
2998			new.si_lower = ptr_to_compat(from->si_lower);
2999			new.si_upper = ptr_to_compat(from->si_upper);
3000		}
3001#endif
3002#ifdef SEGV_PKUERR
3003		if ((from->si_signo == SIGSEGV) &&
3004		    (from->si_code == SEGV_PKUERR))
3005			new.si_pkey = from->si_pkey;
3006#endif
3007
3008		break;
3009	case SIL_CHLD:
3010		new.si_pid    = from->si_pid;
3011		new.si_uid    = from->si_uid;
3012		new.si_status = from->si_status;
3013#ifdef CONFIG_X86_X32_ABI
3014		if (x32_ABI) {
3015			new._sifields._sigchld_x32._utime = from->si_utime;
3016			new._sifields._sigchld_x32._stime = from->si_stime;
3017		} else
3018#endif
3019		{
3020			new.si_utime = from->si_utime;
3021			new.si_stime = from->si_stime;
3022		}
3023		break;
3024	case SIL_RT:
3025		new.si_pid = from->si_pid;
3026		new.si_uid = from->si_uid;
3027		new.si_int = from->si_int;
3028		break;
3029	case SIL_SYS:
3030		new.si_call_addr = ptr_to_compat(from->si_call_addr);
3031		new.si_syscall   = from->si_syscall;
3032		new.si_arch      = from->si_arch;
3033		break;
3034	}
 
3035
 
 
 
 
 
 
3036	if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3037		return -EFAULT;
3038
3039	return 0;
3040}
3041
3042int copy_siginfo_from_user32(struct siginfo *to,
3043			     const struct compat_siginfo __user *ufrom)
3044{
3045	struct compat_siginfo from;
3046
3047	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3048		return -EFAULT;
3049
3050	clear_siginfo(to);
3051	to->si_signo = from.si_signo;
3052	to->si_errno = from.si_errno;
3053	to->si_code  = from.si_code;
3054	switch(siginfo_layout(from.si_signo, from.si_code)) {
3055	case SIL_KILL:
3056		to->si_pid = from.si_pid;
3057		to->si_uid = from.si_uid;
3058		break;
3059	case SIL_TIMER:
3060		to->si_tid     = from.si_tid;
3061		to->si_overrun = from.si_overrun;
3062		to->si_int     = from.si_int;
3063		break;
3064	case SIL_POLL:
3065		to->si_band = from.si_band;
3066		to->si_fd   = from.si_fd;
3067		break;
3068	case SIL_FAULT:
3069		to->si_addr = compat_ptr(from.si_addr);
3070#ifdef __ARCH_SI_TRAPNO
3071		to->si_trapno = from.si_trapno;
3072#endif
3073#ifdef BUS_MCEERR_AR
3074		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AR))
3075			to->si_addr_lsb = from.si_addr_lsb;
3076#endif
3077#ifdef BUS_MCEER_AO
3078		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AO))
3079			to->si_addr_lsb = from.si_addr_lsb;
3080#endif
3081#ifdef SEGV_BNDERR
3082		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) {
3083			to->si_lower = compat_ptr(from.si_lower);
3084			to->si_upper = compat_ptr(from.si_upper);
3085		}
3086#endif
3087#ifdef SEGV_PKUERR
3088		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR))
3089			to->si_pkey = from.si_pkey;
3090#endif
 
 
3091		break;
3092	case SIL_CHLD:
3093		to->si_pid    = from.si_pid;
3094		to->si_uid    = from.si_uid;
3095		to->si_status = from.si_status;
3096#ifdef CONFIG_X86_X32_ABI
3097		if (in_x32_syscall()) {
3098			to->si_utime = from._sifields._sigchld_x32._utime;
3099			to->si_stime = from._sifields._sigchld_x32._stime;
3100		} else
3101#endif
3102		{
3103			to->si_utime = from.si_utime;
3104			to->si_stime = from.si_stime;
3105		}
3106		break;
3107	case SIL_RT:
3108		to->si_pid = from.si_pid;
3109		to->si_uid = from.si_uid;
3110		to->si_int = from.si_int;
3111		break;
3112	case SIL_SYS:
3113		to->si_call_addr = compat_ptr(from.si_call_addr);
3114		to->si_syscall   = from.si_syscall;
3115		to->si_arch      = from.si_arch;
3116		break;
3117	}
3118	return 0;
3119}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3120#endif /* CONFIG_COMPAT */
3121
3122/**
3123 *  do_sigtimedwait - wait for queued signals specified in @which
3124 *  @which: queued signals to wait for
3125 *  @info: if non-null, the signal's siginfo is returned here
3126 *  @ts: upper bound on process time suspension
3127 */
3128static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
3129		    const struct timespec *ts)
3130{
3131	ktime_t *to = NULL, timeout = KTIME_MAX;
3132	struct task_struct *tsk = current;
3133	sigset_t mask = *which;
 
3134	int sig, ret = 0;
3135
3136	if (ts) {
3137		if (!timespec_valid(ts))
3138			return -EINVAL;
3139		timeout = timespec_to_ktime(*ts);
3140		to = &timeout;
3141	}
3142
3143	/*
3144	 * Invert the set of allowed signals to get those we want to block.
3145	 */
3146	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3147	signotset(&mask);
3148
3149	spin_lock_irq(&tsk->sighand->siglock);
3150	sig = dequeue_signal(tsk, &mask, info);
3151	if (!sig && timeout) {
3152		/*
3153		 * None ready, temporarily unblock those we're interested
3154		 * while we are sleeping in so that we'll be awakened when
3155		 * they arrive. Unblocking is always fine, we can avoid
3156		 * set_current_blocked().
3157		 */
3158		tsk->real_blocked = tsk->blocked;
3159		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3160		recalc_sigpending();
3161		spin_unlock_irq(&tsk->sighand->siglock);
3162
3163		__set_current_state(TASK_INTERRUPTIBLE);
3164		ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3165							 HRTIMER_MODE_REL);
3166		spin_lock_irq(&tsk->sighand->siglock);
3167		__set_task_blocked(tsk, &tsk->real_blocked);
3168		sigemptyset(&tsk->real_blocked);
3169		sig = dequeue_signal(tsk, &mask, info);
3170	}
3171	spin_unlock_irq(&tsk->sighand->siglock);
3172
3173	if (sig)
3174		return sig;
3175	return ret ? -EINTR : -EAGAIN;
3176}
3177
3178/**
3179 *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
3180 *			in @uthese
3181 *  @uthese: queued signals to wait for
3182 *  @uinfo: if non-null, the signal's siginfo is returned here
3183 *  @uts: upper bound on process time suspension
3184 *  @sigsetsize: size of sigset_t type
3185 */
3186SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3187		siginfo_t __user *, uinfo, const struct timespec __user *, uts,
 
3188		size_t, sigsetsize)
3189{
3190	sigset_t these;
3191	struct timespec ts;
3192	siginfo_t info;
3193	int ret;
3194
3195	/* XXX: Don't preclude handling different sized sigset_t's.  */
3196	if (sigsetsize != sizeof(sigset_t))
3197		return -EINVAL;
3198
3199	if (copy_from_user(&these, uthese, sizeof(these)))
3200		return -EFAULT;
3201
3202	if (uts) {
3203		if (copy_from_user(&ts, uts, sizeof(ts)))
3204			return -EFAULT;
3205	}
3206
3207	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3208
3209	if (ret > 0 && uinfo) {
3210		if (copy_siginfo_to_user(uinfo, &info))
3211			ret = -EFAULT;
3212	}
3213
3214	return ret;
3215}
3216
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3217#ifdef CONFIG_COMPAT
3218COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3219		struct compat_siginfo __user *, uinfo,
3220		struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
3221{
3222	sigset_t s;
3223	struct timespec t;
3224	siginfo_t info;
3225	long ret;
3226
3227	if (sigsetsize != sizeof(sigset_t))
3228		return -EINVAL;
3229
3230	if (get_compat_sigset(&s, uthese))
3231		return -EFAULT;
3232
3233	if (uts) {
3234		if (compat_get_timespec(&t, uts))
3235			return -EFAULT;
3236	}
3237
3238	ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3239
3240	if (ret > 0 && uinfo) {
3241		if (copy_siginfo_to_user32(uinfo, &info))
3242			ret = -EFAULT;
3243	}
3244
3245	return ret;
3246}
3247#endif
 
 
 
 
 
 
 
 
 
 
 
 
3248
3249/**
3250 *  sys_kill - send a signal to a process
3251 *  @pid: the PID of the process
3252 *  @sig: signal to be sent
3253 */
3254SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3255{
3256	struct siginfo info;
3257
3258	clear_siginfo(&info);
3259	info.si_signo = sig;
3260	info.si_errno = 0;
3261	info.si_code = SI_USER;
3262	info.si_pid = task_tgid_vnr(current);
3263	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3264
3265	return kill_something_info(sig, &info, pid);
3266}
3267
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3268static int
3269do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
3270{
3271	struct task_struct *p;
3272	int error = -ESRCH;
3273
3274	rcu_read_lock();
3275	p = find_task_by_vpid(pid);
3276	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3277		error = check_kill_permission(sig, info, p);
3278		/*
3279		 * The null signal is a permissions and process existence
3280		 * probe.  No signal is actually delivered.
3281		 */
3282		if (!error && sig) {
3283			error = do_send_sig_info(sig, info, p, false);
3284			/*
3285			 * If lock_task_sighand() failed we pretend the task
3286			 * dies after receiving the signal. The window is tiny,
3287			 * and the signal is private anyway.
3288			 */
3289			if (unlikely(error == -ESRCH))
3290				error = 0;
3291		}
3292	}
3293	rcu_read_unlock();
3294
3295	return error;
3296}
3297
3298static int do_tkill(pid_t tgid, pid_t pid, int sig)
3299{
3300	struct siginfo info;
3301
3302	clear_siginfo(&info);
3303	info.si_signo = sig;
3304	info.si_errno = 0;
3305	info.si_code = SI_TKILL;
3306	info.si_pid = task_tgid_vnr(current);
3307	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
3308
3309	return do_send_specific(tgid, pid, sig, &info);
3310}
3311
3312/**
3313 *  sys_tgkill - send signal to one specific thread
3314 *  @tgid: the thread group ID of the thread
3315 *  @pid: the PID of the thread
3316 *  @sig: signal to be sent
3317 *
3318 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
3319 *  exists but it's not belonging to the target process anymore. This
3320 *  method solves the problem of threads exiting and PIDs getting reused.
3321 */
3322SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3323{
3324	/* This is only valid for single tasks */
3325	if (pid <= 0 || tgid <= 0)
3326		return -EINVAL;
3327
3328	return do_tkill(tgid, pid, sig);
3329}
3330
3331/**
3332 *  sys_tkill - send signal to one specific task
3333 *  @pid: the PID of the task
3334 *  @sig: signal to be sent
3335 *
3336 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
3337 */
3338SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
3339{
3340	/* This is only valid for single tasks */
3341	if (pid <= 0)
3342		return -EINVAL;
3343
3344	return do_tkill(0, pid, sig);
3345}
3346
3347static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
3348{
3349	/* Not even root can pretend to send signals from the kernel.
3350	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3351	 */
3352	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3353	    (task_pid_vnr(current) != pid))
3354		return -EPERM;
3355
3356	info->si_signo = sig;
3357
3358	/* POSIX.1b doesn't mention process groups.  */
3359	return kill_proc_info(sig, info, pid);
3360}
3361
3362/**
3363 *  sys_rt_sigqueueinfo - send signal information to a signal
3364 *  @pid: the PID of the thread
3365 *  @sig: signal to be sent
3366 *  @uinfo: signal info to be sent
3367 */
3368SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
3369		siginfo_t __user *, uinfo)
3370{
3371	siginfo_t info;
3372	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3373		return -EFAULT;
 
3374	return do_rt_sigqueueinfo(pid, sig, &info);
3375}
3376
3377#ifdef CONFIG_COMPAT
3378COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
3379			compat_pid_t, pid,
3380			int, sig,
3381			struct compat_siginfo __user *, uinfo)
3382{
3383	siginfo_t info;
3384	int ret = copy_siginfo_from_user32(&info, uinfo);
3385	if (unlikely(ret))
3386		return ret;
3387	return do_rt_sigqueueinfo(pid, sig, &info);
3388}
3389#endif
3390
3391static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3392{
3393	/* This is only valid for single tasks */
3394	if (pid <= 0 || tgid <= 0)
3395		return -EINVAL;
3396
3397	/* Not even root can pretend to send signals from the kernel.
3398	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
3399	 */
3400	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3401	    (task_pid_vnr(current) != pid))
3402		return -EPERM;
3403
3404	info->si_signo = sig;
3405
3406	return do_send_specific(tgid, pid, sig, info);
3407}
3408
3409SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
3410		siginfo_t __user *, uinfo)
3411{
3412	siginfo_t info;
3413
3414	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
3415		return -EFAULT;
3416
3417	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3418}
3419
3420#ifdef CONFIG_COMPAT
3421COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
3422			compat_pid_t, tgid,
3423			compat_pid_t, pid,
3424			int, sig,
3425			struct compat_siginfo __user *, uinfo)
3426{
3427	siginfo_t info;
3428
3429	if (copy_siginfo_from_user32(&info, uinfo))
3430		return -EFAULT;
3431	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
3432}
3433#endif
3434
3435/*
3436 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3437 */
3438void kernel_sigaction(int sig, __sighandler_t action)
3439{
3440	spin_lock_irq(&current->sighand->siglock);
3441	current->sighand->action[sig - 1].sa.sa_handler = action;
3442	if (action == SIG_IGN) {
3443		sigset_t mask;
3444
3445		sigemptyset(&mask);
3446		sigaddset(&mask, sig);
3447
3448		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
3449		flush_sigqueue_mask(&mask, &current->pending);
3450		recalc_sigpending();
3451	}
3452	spin_unlock_irq(&current->sighand->siglock);
3453}
3454EXPORT_SYMBOL(kernel_sigaction);
3455
3456void __weak sigaction_compat_abi(struct k_sigaction *act,
3457		struct k_sigaction *oact)
3458{
3459}
3460
3461int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
3462{
3463	struct task_struct *p = current, *t;
3464	struct k_sigaction *k;
3465	sigset_t mask;
3466
3467	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
3468		return -EINVAL;
3469
3470	k = &p->sighand->action[sig-1];
3471
3472	spin_lock_irq(&p->sighand->siglock);
 
 
 
 
3473	if (oact)
3474		*oact = *k;
3475
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3476	sigaction_compat_abi(act, oact);
3477
3478	if (act) {
3479		sigdelsetmask(&act->sa.sa_mask,
3480			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3481		*k = *act;
3482		/*
3483		 * POSIX 3.3.1.3:
3484		 *  "Setting a signal action to SIG_IGN for a signal that is
3485		 *   pending shall cause the pending signal to be discarded,
3486		 *   whether or not it is blocked."
3487		 *
3488		 *  "Setting a signal action to SIG_DFL for a signal that is
3489		 *   pending and whose default action is to ignore the signal
3490		 *   (for example, SIGCHLD), shall cause the pending signal to
3491		 *   be discarded, whether or not it is blocked"
3492		 */
3493		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3494			sigemptyset(&mask);
3495			sigaddset(&mask, sig);
3496			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
3497			for_each_thread(p, t)
3498				flush_sigqueue_mask(&mask, &t->pending);
3499		}
3500	}
3501
3502	spin_unlock_irq(&p->sighand->siglock);
3503	return 0;
3504}
3505
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3506static int
3507do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
 
3508{
3509	struct task_struct *t = current;
 
3510
3511	if (oss) {
3512		memset(oss, 0, sizeof(stack_t));
3513		oss->ss_sp = (void __user *) t->sas_ss_sp;
3514		oss->ss_size = t->sas_ss_size;
3515		oss->ss_flags = sas_ss_flags(sp) |
3516			(current->sas_ss_flags & SS_FLAG_BITS);
3517	}
3518
3519	if (ss) {
3520		void __user *ss_sp = ss->ss_sp;
3521		size_t ss_size = ss->ss_size;
3522		unsigned ss_flags = ss->ss_flags;
3523		int ss_mode;
3524
3525		if (unlikely(on_sig_stack(sp)))
3526			return -EPERM;
3527
3528		ss_mode = ss_flags & ~SS_FLAG_BITS;
3529		if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
3530				ss_mode != 0))
3531			return -EINVAL;
3532
 
 
 
 
 
 
 
 
 
 
3533		if (ss_mode == SS_DISABLE) {
3534			ss_size = 0;
3535			ss_sp = NULL;
3536		} else {
3537			if (unlikely(ss_size < MINSIGSTKSZ))
3538				return -ENOMEM;
 
 
3539		}
3540
3541		t->sas_ss_sp = (unsigned long) ss_sp;
3542		t->sas_ss_size = ss_size;
3543		t->sas_ss_flags = ss_flags;
 
 
3544	}
3545	return 0;
3546}
3547
3548SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
3549{
3550	stack_t new, old;
3551	int err;
3552	if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
3553		return -EFAULT;
3554	err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
3555			      current_user_stack_pointer());
 
3556	if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
3557		err = -EFAULT;
3558	return err;
3559}
3560
3561int restore_altstack(const stack_t __user *uss)
3562{
3563	stack_t new;
3564	if (copy_from_user(&new, uss, sizeof(stack_t)))
3565		return -EFAULT;
3566	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
 
3567	/* squash all but EFAULT for now */
3568	return 0;
3569}
3570
3571int __save_altstack(stack_t __user *uss, unsigned long sp)
3572{
3573	struct task_struct *t = current;
3574	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
3575		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3576		__put_user(t->sas_ss_size, &uss->ss_size);
3577	if (err)
3578		return err;
3579	if (t->sas_ss_flags & SS_AUTODISARM)
3580		sas_ss_reset(t);
3581	return 0;
3582}
3583
3584#ifdef CONFIG_COMPAT
3585static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
3586				 compat_stack_t __user *uoss_ptr)
3587{
3588	stack_t uss, uoss;
3589	int ret;
3590
3591	if (uss_ptr) {
3592		compat_stack_t uss32;
3593		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
3594			return -EFAULT;
3595		uss.ss_sp = compat_ptr(uss32.ss_sp);
3596		uss.ss_flags = uss32.ss_flags;
3597		uss.ss_size = uss32.ss_size;
3598	}
3599	ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
3600			     compat_user_stack_pointer());
 
3601	if (ret >= 0 && uoss_ptr)  {
3602		compat_stack_t old;
3603		memset(&old, 0, sizeof(old));
3604		old.ss_sp = ptr_to_compat(uoss.ss_sp);
3605		old.ss_flags = uoss.ss_flags;
3606		old.ss_size = uoss.ss_size;
3607		if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
3608			ret = -EFAULT;
3609	}
3610	return ret;
3611}
3612
3613COMPAT_SYSCALL_DEFINE2(sigaltstack,
3614			const compat_stack_t __user *, uss_ptr,
3615			compat_stack_t __user *, uoss_ptr)
3616{
3617	return do_compat_sigaltstack(uss_ptr, uoss_ptr);
3618}
3619
3620int compat_restore_altstack(const compat_stack_t __user *uss)
3621{
3622	int err = do_compat_sigaltstack(uss, NULL);
3623	/* squash all but -EFAULT for now */
3624	return err == -EFAULT ? err : 0;
3625}
3626
3627int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
3628{
3629	int err;
3630	struct task_struct *t = current;
3631	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
3632			 &uss->ss_sp) |
3633		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3634		__put_user(t->sas_ss_size, &uss->ss_size);
3635	if (err)
3636		return err;
3637	if (t->sas_ss_flags & SS_AUTODISARM)
3638		sas_ss_reset(t);
3639	return 0;
3640}
3641#endif
3642
3643#ifdef __ARCH_WANT_SYS_SIGPENDING
3644
3645/**
3646 *  sys_sigpending - examine pending signals
3647 *  @uset: where mask of pending signal is returned
3648 */
3649SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
3650{
3651	sigset_t set;
3652	int err;
3653
3654	if (sizeof(old_sigset_t) > sizeof(*uset))
3655		return -EINVAL;
3656
3657	err = do_sigpending(&set);
3658	if (!err && copy_to_user(uset, &set, sizeof(old_sigset_t)))
3659		err = -EFAULT;
3660	return err;
 
 
3661}
3662
3663#ifdef CONFIG_COMPAT
3664COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
3665{
3666	sigset_t set;
3667	int err = do_sigpending(&set);
3668	if (!err)
3669		err = put_user(set.sig[0], set32);
3670	return err;
3671}
3672#endif
3673
3674#endif
3675
3676#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3677/**
3678 *  sys_sigprocmask - examine and change blocked signals
3679 *  @how: whether to add, remove, or set signals
3680 *  @nset: signals to add or remove (if non-null)
3681 *  @oset: previous value of signal mask if non-null
3682 *
3683 * Some platforms have their own version with special arguments;
3684 * others support only sys_rt_sigprocmask.
3685 */
3686
3687SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3688		old_sigset_t __user *, oset)
3689{
3690	old_sigset_t old_set, new_set;
3691	sigset_t new_blocked;
3692
3693	old_set = current->blocked.sig[0];
3694
3695	if (nset) {
3696		if (copy_from_user(&new_set, nset, sizeof(*nset)))
3697			return -EFAULT;
3698
3699		new_blocked = current->blocked;
3700
3701		switch (how) {
3702		case SIG_BLOCK:
3703			sigaddsetmask(&new_blocked, new_set);
3704			break;
3705		case SIG_UNBLOCK:
3706			sigdelsetmask(&new_blocked, new_set);
3707			break;
3708		case SIG_SETMASK:
3709			new_blocked.sig[0] = new_set;
3710			break;
3711		default:
3712			return -EINVAL;
3713		}
3714
3715		set_current_blocked(&new_blocked);
3716	}
3717
3718	if (oset) {
3719		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3720			return -EFAULT;
3721	}
3722
3723	return 0;
3724}
3725#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
3726
3727#ifndef CONFIG_ODD_RT_SIGACTION
3728/**
3729 *  sys_rt_sigaction - alter an action taken by a process
3730 *  @sig: signal to be sent
3731 *  @act: new sigaction
3732 *  @oact: used to save the previous sigaction
3733 *  @sigsetsize: size of sigset_t type
3734 */
3735SYSCALL_DEFINE4(rt_sigaction, int, sig,
3736		const struct sigaction __user *, act,
3737		struct sigaction __user *, oact,
3738		size_t, sigsetsize)
3739{
3740	struct k_sigaction new_sa, old_sa;
3741	int ret = -EINVAL;
3742
3743	/* XXX: Don't preclude handling different sized sigset_t's.  */
3744	if (sigsetsize != sizeof(sigset_t))
3745		goto out;
3746
3747	if (act) {
3748		if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
3749			return -EFAULT;
3750	}
3751
3752	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
 
 
3753
3754	if (!ret && oact) {
3755		if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
3756			return -EFAULT;
3757	}
3758out:
3759	return ret;
3760}
3761#ifdef CONFIG_COMPAT
3762COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
3763		const struct compat_sigaction __user *, act,
3764		struct compat_sigaction __user *, oact,
3765		compat_size_t, sigsetsize)
3766{
3767	struct k_sigaction new_ka, old_ka;
3768#ifdef __ARCH_HAS_SA_RESTORER
3769	compat_uptr_t restorer;
3770#endif
3771	int ret;
3772
3773	/* XXX: Don't preclude handling different sized sigset_t's.  */
3774	if (sigsetsize != sizeof(compat_sigset_t))
3775		return -EINVAL;
3776
3777	if (act) {
3778		compat_uptr_t handler;
3779		ret = get_user(handler, &act->sa_handler);
3780		new_ka.sa.sa_handler = compat_ptr(handler);
3781#ifdef __ARCH_HAS_SA_RESTORER
3782		ret |= get_user(restorer, &act->sa_restorer);
3783		new_ka.sa.sa_restorer = compat_ptr(restorer);
3784#endif
3785		ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
3786		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
3787		if (ret)
3788			return -EFAULT;
3789	}
3790
3791	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3792	if (!ret && oact) {
3793		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
3794			       &oact->sa_handler);
3795		ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
3796					 sizeof(oact->sa_mask));
3797		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
3798#ifdef __ARCH_HAS_SA_RESTORER
3799		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3800				&oact->sa_restorer);
3801#endif
3802	}
3803	return ret;
3804}
3805#endif
3806#endif /* !CONFIG_ODD_RT_SIGACTION */
3807
3808#ifdef CONFIG_OLD_SIGACTION
3809SYSCALL_DEFINE3(sigaction, int, sig,
3810		const struct old_sigaction __user *, act,
3811	        struct old_sigaction __user *, oact)
3812{
3813	struct k_sigaction new_ka, old_ka;
3814	int ret;
3815
3816	if (act) {
3817		old_sigset_t mask;
3818		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3819		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
3820		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
3821		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3822		    __get_user(mask, &act->sa_mask))
3823			return -EFAULT;
3824#ifdef __ARCH_HAS_KA_RESTORER
3825		new_ka.ka_restorer = NULL;
3826#endif
3827		siginitset(&new_ka.sa.sa_mask, mask);
3828	}
3829
3830	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3831
3832	if (!ret && oact) {
3833		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3834		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
3835		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
3836		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3837		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3838			return -EFAULT;
3839	}
3840
3841	return ret;
3842}
3843#endif
3844#ifdef CONFIG_COMPAT_OLD_SIGACTION
3845COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
3846		const struct compat_old_sigaction __user *, act,
3847	        struct compat_old_sigaction __user *, oact)
3848{
3849	struct k_sigaction new_ka, old_ka;
3850	int ret;
3851	compat_old_sigset_t mask;
3852	compat_uptr_t handler, restorer;
3853
3854	if (act) {
3855		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
3856		    __get_user(handler, &act->sa_handler) ||
3857		    __get_user(restorer, &act->sa_restorer) ||
3858		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
3859		    __get_user(mask, &act->sa_mask))
3860			return -EFAULT;
3861
3862#ifdef __ARCH_HAS_KA_RESTORER
3863		new_ka.ka_restorer = NULL;
3864#endif
3865		new_ka.sa.sa_handler = compat_ptr(handler);
3866		new_ka.sa.sa_restorer = compat_ptr(restorer);
3867		siginitset(&new_ka.sa.sa_mask, mask);
3868	}
3869
3870	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
3871
3872	if (!ret && oact) {
3873		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
3874		    __put_user(ptr_to_compat(old_ka.sa.sa_handler),
3875			       &oact->sa_handler) ||
3876		    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
3877			       &oact->sa_restorer) ||
3878		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
3879		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
3880			return -EFAULT;
3881	}
3882	return ret;
3883}
3884#endif
3885
3886#ifdef CONFIG_SGETMASK_SYSCALL
3887
3888/*
3889 * For backwards compatibility.  Functionality superseded by sigprocmask.
3890 */
3891SYSCALL_DEFINE0(sgetmask)
3892{
3893	/* SMP safe */
3894	return current->blocked.sig[0];
3895}
3896
3897SYSCALL_DEFINE1(ssetmask, int, newmask)
3898{
3899	int old = current->blocked.sig[0];
3900	sigset_t newset;
3901
3902	siginitset(&newset, newmask);
3903	set_current_blocked(&newset);
3904
3905	return old;
3906}
3907#endif /* CONFIG_SGETMASK_SYSCALL */
3908
3909#ifdef __ARCH_WANT_SYS_SIGNAL
3910/*
3911 * For backwards compatibility.  Functionality superseded by sigaction.
3912 */
3913SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
3914{
3915	struct k_sigaction new_sa, old_sa;
3916	int ret;
3917
3918	new_sa.sa.sa_handler = handler;
3919	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3920	sigemptyset(&new_sa.sa.sa_mask);
3921
3922	ret = do_sigaction(sig, &new_sa, &old_sa);
3923
3924	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
3925}
3926#endif /* __ARCH_WANT_SYS_SIGNAL */
3927
3928#ifdef __ARCH_WANT_SYS_PAUSE
3929
3930SYSCALL_DEFINE0(pause)
3931{
3932	while (!signal_pending(current)) {
3933		__set_current_state(TASK_INTERRUPTIBLE);
3934		schedule();
3935	}
3936	return -ERESTARTNOHAND;
3937}
3938
3939#endif
3940
3941static int sigsuspend(sigset_t *set)
3942{
3943	current->saved_sigmask = current->blocked;
3944	set_current_blocked(set);
3945
3946	while (!signal_pending(current)) {
3947		__set_current_state(TASK_INTERRUPTIBLE);
3948		schedule();
3949	}
3950	set_restore_sigmask();
3951	return -ERESTARTNOHAND;
3952}
3953
3954/**
3955 *  sys_rt_sigsuspend - replace the signal mask for a value with the
3956 *	@unewset value until a signal is received
3957 *  @unewset: new signal mask value
3958 *  @sigsetsize: size of sigset_t type
3959 */
3960SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3961{
3962	sigset_t newset;
3963
3964	/* XXX: Don't preclude handling different sized sigset_t's.  */
3965	if (sigsetsize != sizeof(sigset_t))
3966		return -EINVAL;
3967
3968	if (copy_from_user(&newset, unewset, sizeof(newset)))
3969		return -EFAULT;
3970	return sigsuspend(&newset);
3971}
3972 
3973#ifdef CONFIG_COMPAT
3974COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
3975{
3976	sigset_t newset;
3977
3978	/* XXX: Don't preclude handling different sized sigset_t's.  */
3979	if (sigsetsize != sizeof(sigset_t))
3980		return -EINVAL;
3981
3982	if (get_compat_sigset(&newset, unewset))
3983		return -EFAULT;
3984	return sigsuspend(&newset);
3985}
3986#endif
3987
3988#ifdef CONFIG_OLD_SIGSUSPEND
3989SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
3990{
3991	sigset_t blocked;
3992	siginitset(&blocked, mask);
3993	return sigsuspend(&blocked);
3994}
3995#endif
3996#ifdef CONFIG_OLD_SIGSUSPEND3
3997SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
3998{
3999	sigset_t blocked;
4000	siginitset(&blocked, mask);
4001	return sigsuspend(&blocked);
4002}
4003#endif
4004
4005__weak const char *arch_vma_name(struct vm_area_struct *vma)
4006{
4007	return NULL;
4008}
4009
4010void __init signals_init(void)
4011{
4012	/* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
4013	BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
4014		!= offsetof(struct siginfo, _sifields._pad));
4015	BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4016
4017	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4018}
4019
4020#ifdef CONFIG_KGDB_KDB
4021#include <linux/kdb.h>
4022/*
4023 * kdb_send_sig - Allows kdb to send signals without exposing
4024 * signal internals.  This function checks if the required locks are
4025 * available before calling the main signal code, to avoid kdb
4026 * deadlocks.
4027 */
4028void kdb_send_sig(struct task_struct *t, int sig)
4029{
4030	static struct task_struct *kdb_prev_t;
4031	int new_t, ret;
4032	if (!spin_trylock(&t->sighand->siglock)) {
4033		kdb_printf("Can't do kill command now.\n"
4034			   "The sigmask lock is held somewhere else in "
4035			   "kernel, try again later\n");
4036		return;
4037	}
4038	new_t = kdb_prev_t != t;
4039	kdb_prev_t = t;
4040	if (t->state != TASK_RUNNING && new_t) {
4041		spin_unlock(&t->sighand->siglock);
4042		kdb_printf("Process is not RUNNING, sending a signal from "
4043			   "kdb risks deadlock\n"
4044			   "on the run queue locks. "
4045			   "The signal has _not_ been sent.\n"
4046			   "Reissue the kill command if you want to risk "
4047			   "the deadlock.\n");
4048		return;
4049	}
4050	ret = send_signal(sig, SEND_SIG_PRIV, t, false);
4051	spin_unlock(&t->sighand->siglock);
4052	if (ret)
4053		kdb_printf("Fail to deliver Signal %d to process %d.\n",
4054			   sig, t->pid);
4055	else
4056		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4057}
4058#endif	/* CONFIG_KGDB_KDB */
v6.9.4
   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/kernel/signal.c
   4 *
   5 *  Copyright (C) 1991, 1992  Linus Torvalds
   6 *
   7 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
   8 *
   9 *  2003-06-02  Jim Houston - Concurrent Computer Corp.
  10 *		Changes to use preallocated sigqueue structures
  11 *		to allow signals to be sent reliably.
  12 */
  13
  14#include <linux/slab.h>
  15#include <linux/export.h>
  16#include <linux/init.h>
  17#include <linux/sched/mm.h>
  18#include <linux/sched/user.h>
  19#include <linux/sched/debug.h>
  20#include <linux/sched/task.h>
  21#include <linux/sched/task_stack.h>
  22#include <linux/sched/cputime.h>
  23#include <linux/file.h>
  24#include <linux/fs.h>
  25#include <linux/mm.h>
  26#include <linux/proc_fs.h>
  27#include <linux/tty.h>
  28#include <linux/binfmts.h>
  29#include <linux/coredump.h>
  30#include <linux/security.h>
  31#include <linux/syscalls.h>
  32#include <linux/ptrace.h>
  33#include <linux/signal.h>
  34#include <linux/signalfd.h>
  35#include <linux/ratelimit.h>
  36#include <linux/task_work.h>
  37#include <linux/capability.h>
  38#include <linux/freezer.h>
  39#include <linux/pid_namespace.h>
  40#include <linux/nsproxy.h>
  41#include <linux/user_namespace.h>
  42#include <linux/uprobes.h>
  43#include <linux/compat.h>
  44#include <linux/cn_proc.h>
  45#include <linux/compiler.h>
  46#include <linux/posix-timers.h>
  47#include <linux/cgroup.h>
  48#include <linux/audit.h>
  49#include <linux/sysctl.h>
  50#include <uapi/linux/pidfd.h>
  51
  52#define CREATE_TRACE_POINTS
  53#include <trace/events/signal.h>
  54
  55#include <asm/param.h>
  56#include <linux/uaccess.h>
  57#include <asm/unistd.h>
  58#include <asm/siginfo.h>
  59#include <asm/cacheflush.h>
  60#include <asm/syscall.h>	/* for syscall_get_* */
  61
  62/*
  63 * SLAB caches for signal bits.
  64 */
  65
  66static struct kmem_cache *sigqueue_cachep;
  67
  68int print_fatal_signals __read_mostly;
  69
  70static void __user *sig_handler(struct task_struct *t, int sig)
  71{
  72	return t->sighand->action[sig - 1].sa.sa_handler;
  73}
  74
  75static inline bool sig_handler_ignored(void __user *handler, int sig)
  76{
  77	/* Is it explicitly or implicitly ignored? */
  78	return handler == SIG_IGN ||
  79	       (handler == SIG_DFL && sig_kernel_ignore(sig));
  80}
  81
  82static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
  83{
  84	void __user *handler;
  85
  86	handler = sig_handler(t, sig);
  87
  88	/* SIGKILL and SIGSTOP may not be sent to the global init */
  89	if (unlikely(is_global_init(t) && sig_kernel_only(sig)))
  90		return true;
  91
  92	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
  93	    handler == SIG_DFL && !(force && sig_kernel_only(sig)))
  94		return true;
  95
  96	/* Only allow kernel generated signals to this kthread */
  97	if (unlikely((t->flags & PF_KTHREAD) &&
  98		     (handler == SIG_KTHREAD_KERNEL) && !force))
  99		return true;
 100
 101	return sig_handler_ignored(handler, sig);
 102}
 103
 104static bool sig_ignored(struct task_struct *t, int sig, bool force)
 105{
 106	/*
 107	 * Blocked signals are never ignored, since the
 108	 * signal handler may change by the time it is
 109	 * unblocked.
 110	 */
 111	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
 112		return false;
 113
 114	/*
 115	 * Tracers may want to know about even ignored signal unless it
 116	 * is SIGKILL which can't be reported anyway but can be ignored
 117	 * by SIGNAL_UNKILLABLE task.
 118	 */
 119	if (t->ptrace && sig != SIGKILL)
 120		return false;
 121
 122	return sig_task_ignored(t, sig, force);
 123}
 124
 125/*
 126 * Re-calculate pending state from the set of locally pending
 127 * signals, globally pending signals, and blocked signals.
 128 */
 129static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
 130{
 131	unsigned long ready;
 132	long i;
 133
 134	switch (_NSIG_WORDS) {
 135	default:
 136		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
 137			ready |= signal->sig[i] &~ blocked->sig[i];
 138		break;
 139
 140	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
 141		ready |= signal->sig[2] &~ blocked->sig[2];
 142		ready |= signal->sig[1] &~ blocked->sig[1];
 143		ready |= signal->sig[0] &~ blocked->sig[0];
 144		break;
 145
 146	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
 147		ready |= signal->sig[0] &~ blocked->sig[0];
 148		break;
 149
 150	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
 151	}
 152	return ready !=	0;
 153}
 154
 155#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
 156
 157static bool recalc_sigpending_tsk(struct task_struct *t)
 158{
 159	if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
 160	    PENDING(&t->pending, &t->blocked) ||
 161	    PENDING(&t->signal->shared_pending, &t->blocked) ||
 162	    cgroup_task_frozen(t)) {
 163		set_tsk_thread_flag(t, TIF_SIGPENDING);
 164		return true;
 165	}
 166
 167	/*
 168	 * We must never clear the flag in another thread, or in current
 169	 * when it's possible the current syscall is returning -ERESTART*.
 170	 * So we don't clear it here, and only callers who know they should do.
 171	 */
 172	return false;
 
 
 
 
 
 
 
 
 
 
 173}
 174
 175void recalc_sigpending(void)
 176{
 177	if (!recalc_sigpending_tsk(current) && !freezing(current))
 
 178		clear_thread_flag(TIF_SIGPENDING);
 179
 180}
 181EXPORT_SYMBOL(recalc_sigpending);
 182
 183void calculate_sigpending(void)
 184{
 185	/* Have any signals or users of TIF_SIGPENDING been delayed
 186	 * until after fork?
 187	 */
 188	spin_lock_irq(&current->sighand->siglock);
 189	set_tsk_thread_flag(current, TIF_SIGPENDING);
 190	recalc_sigpending();
 191	spin_unlock_irq(&current->sighand->siglock);
 192}
 193
 194/* Given the mask, find the first available signal that should be serviced. */
 195
 196#define SYNCHRONOUS_MASK \
 197	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
 198	 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
 199
 200int next_signal(struct sigpending *pending, sigset_t *mask)
 201{
 202	unsigned long i, *s, *m, x;
 203	int sig = 0;
 204
 205	s = pending->signal.sig;
 206	m = mask->sig;
 207
 208	/*
 209	 * Handle the first word specially: it contains the
 210	 * synchronous signals that need to be dequeued first.
 211	 */
 212	x = *s &~ *m;
 213	if (x) {
 214		if (x & SYNCHRONOUS_MASK)
 215			x &= SYNCHRONOUS_MASK;
 216		sig = ffz(~x) + 1;
 217		return sig;
 218	}
 219
 220	switch (_NSIG_WORDS) {
 221	default:
 222		for (i = 1; i < _NSIG_WORDS; ++i) {
 223			x = *++s &~ *++m;
 224			if (!x)
 225				continue;
 226			sig = ffz(~x) + i*_NSIG_BPW + 1;
 227			break;
 228		}
 229		break;
 230
 231	case 2:
 232		x = s[1] &~ m[1];
 233		if (!x)
 234			break;
 235		sig = ffz(~x) + _NSIG_BPW + 1;
 236		break;
 237
 238	case 1:
 239		/* Nothing to do */
 240		break;
 241	}
 242
 243	return sig;
 244}
 245
 246static inline void print_dropped_signal(int sig)
 247{
 248	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
 249
 250	if (!print_fatal_signals)
 251		return;
 252
 253	if (!__ratelimit(&ratelimit_state))
 254		return;
 255
 256	pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
 257				current->comm, current->pid, sig);
 258}
 259
 260/**
 261 * task_set_jobctl_pending - set jobctl pending bits
 262 * @task: target task
 263 * @mask: pending bits to set
 264 *
 265 * Clear @mask from @task->jobctl.  @mask must be subset of
 266 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
 267 * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
 268 * cleared.  If @task is already being killed or exiting, this function
 269 * becomes noop.
 270 *
 271 * CONTEXT:
 272 * Must be called with @task->sighand->siglock held.
 273 *
 274 * RETURNS:
 275 * %true if @mask is set, %false if made noop because @task was dying.
 276 */
 277bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
 278{
 279	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
 280			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
 281	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
 282
 283	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
 284		return false;
 285
 286	if (mask & JOBCTL_STOP_SIGMASK)
 287		task->jobctl &= ~JOBCTL_STOP_SIGMASK;
 288
 289	task->jobctl |= mask;
 290	return true;
 291}
 292
 293/**
 294 * task_clear_jobctl_trapping - clear jobctl trapping bit
 295 * @task: target task
 296 *
 297 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
 298 * Clear it and wake up the ptracer.  Note that we don't need any further
 299 * locking.  @task->siglock guarantees that @task->parent points to the
 300 * ptracer.
 301 *
 302 * CONTEXT:
 303 * Must be called with @task->sighand->siglock held.
 304 */
 305void task_clear_jobctl_trapping(struct task_struct *task)
 306{
 307	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
 308		task->jobctl &= ~JOBCTL_TRAPPING;
 309		smp_mb();	/* advised by wake_up_bit() */
 310		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
 311	}
 312}
 313
 314/**
 315 * task_clear_jobctl_pending - clear jobctl pending bits
 316 * @task: target task
 317 * @mask: pending bits to clear
 318 *
 319 * Clear @mask from @task->jobctl.  @mask must be subset of
 320 * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
 321 * STOP bits are cleared together.
 322 *
 323 * If clearing of @mask leaves no stop or trap pending, this function calls
 324 * task_clear_jobctl_trapping().
 325 *
 326 * CONTEXT:
 327 * Must be called with @task->sighand->siglock held.
 328 */
 329void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
 330{
 331	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
 332
 333	if (mask & JOBCTL_STOP_PENDING)
 334		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
 335
 336	task->jobctl &= ~mask;
 337
 338	if (!(task->jobctl & JOBCTL_PENDING_MASK))
 339		task_clear_jobctl_trapping(task);
 340}
 341
 342/**
 343 * task_participate_group_stop - participate in a group stop
 344 * @task: task participating in a group stop
 345 *
 346 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
 347 * Group stop states are cleared and the group stop count is consumed if
 348 * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
 349 * stop, the appropriate `SIGNAL_*` flags are set.
 350 *
 351 * CONTEXT:
 352 * Must be called with @task->sighand->siglock held.
 353 *
 354 * RETURNS:
 355 * %true if group stop completion should be notified to the parent, %false
 356 * otherwise.
 357 */
 358static bool task_participate_group_stop(struct task_struct *task)
 359{
 360	struct signal_struct *sig = task->signal;
 361	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
 362
 363	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
 364
 365	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
 366
 367	if (!consume)
 368		return false;
 369
 370	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
 371		sig->group_stop_count--;
 372
 373	/*
 374	 * Tell the caller to notify completion iff we are entering into a
 375	 * fresh group stop.  Read comment in do_signal_stop() for details.
 376	 */
 377	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
 378		signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
 379		return true;
 380	}
 381	return false;
 382}
 383
 384void task_join_group_stop(struct task_struct *task)
 385{
 386	unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK;
 387	struct signal_struct *sig = current->signal;
 388
 389	if (sig->group_stop_count) {
 390		sig->group_stop_count++;
 391		mask |= JOBCTL_STOP_CONSUME;
 392	} else if (!(sig->flags & SIGNAL_STOP_STOPPED))
 393		return;
 394
 395	/* Have the new thread join an on-going signal group stop */
 396	task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
 397}
 398
 399/*
 400 * allocate a new signal queue record
 401 * - this may be called without locks if and only if t == current, otherwise an
 402 *   appropriate lock must be held to stop the target task from exiting
 403 */
 404static struct sigqueue *
 405__sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
 406		 int override_rlimit, const unsigned int sigqueue_flags)
 407{
 408	struct sigqueue *q = NULL;
 409	struct ucounts *ucounts;
 410	long sigpending;
 411
 412	/*
 413	 * Protect access to @t credentials. This can go away when all
 414	 * callers hold rcu read lock.
 415	 *
 416	 * NOTE! A pending signal will hold on to the user refcount,
 417	 * and we get/put the refcount only when the sigpending count
 418	 * changes from/to zero.
 419	 */
 420	rcu_read_lock();
 421	ucounts = task_ucounts(t);
 422	sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
 423	rcu_read_unlock();
 424	if (!sigpending)
 425		return NULL;
 426
 427	if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
 428		q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
 
 
 429	} else {
 430		print_dropped_signal(sig);
 431	}
 432
 433	if (unlikely(q == NULL)) {
 434		dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
 
 435	} else {
 436		INIT_LIST_HEAD(&q->list);
 437		q->flags = sigqueue_flags;
 438		q->ucounts = ucounts;
 439	}
 
 440	return q;
 441}
 442
 443static void __sigqueue_free(struct sigqueue *q)
 444{
 445	if (q->flags & SIGQUEUE_PREALLOC)
 446		return;
 447	if (q->ucounts) {
 448		dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING);
 449		q->ucounts = NULL;
 450	}
 451	kmem_cache_free(sigqueue_cachep, q);
 452}
 453
 454void flush_sigqueue(struct sigpending *queue)
 455{
 456	struct sigqueue *q;
 457
 458	sigemptyset(&queue->signal);
 459	while (!list_empty(&queue->list)) {
 460		q = list_entry(queue->list.next, struct sigqueue , list);
 461		list_del_init(&q->list);
 462		__sigqueue_free(q);
 463	}
 464}
 465
 466/*
 467 * Flush all pending signals for this kthread.
 468 */
 469void flush_signals(struct task_struct *t)
 470{
 471	unsigned long flags;
 472
 473	spin_lock_irqsave(&t->sighand->siglock, flags);
 474	clear_tsk_thread_flag(t, TIF_SIGPENDING);
 475	flush_sigqueue(&t->pending);
 476	flush_sigqueue(&t->signal->shared_pending);
 477	spin_unlock_irqrestore(&t->sighand->siglock, flags);
 478}
 479EXPORT_SYMBOL(flush_signals);
 480
 481#ifdef CONFIG_POSIX_TIMERS
 482static void __flush_itimer_signals(struct sigpending *pending)
 483{
 484	sigset_t signal, retain;
 485	struct sigqueue *q, *n;
 486
 487	signal = pending->signal;
 488	sigemptyset(&retain);
 489
 490	list_for_each_entry_safe(q, n, &pending->list, list) {
 491		int sig = q->info.si_signo;
 492
 493		if (likely(q->info.si_code != SI_TIMER)) {
 494			sigaddset(&retain, sig);
 495		} else {
 496			sigdelset(&signal, sig);
 497			list_del_init(&q->list);
 498			__sigqueue_free(q);
 499		}
 500	}
 501
 502	sigorsets(&pending->signal, &signal, &retain);
 503}
 504
 505void flush_itimer_signals(void)
 506{
 507	struct task_struct *tsk = current;
 508	unsigned long flags;
 509
 510	spin_lock_irqsave(&tsk->sighand->siglock, flags);
 511	__flush_itimer_signals(&tsk->pending);
 512	__flush_itimer_signals(&tsk->signal->shared_pending);
 513	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 514}
 515#endif
 516
 517void ignore_signals(struct task_struct *t)
 518{
 519	int i;
 520
 521	for (i = 0; i < _NSIG; ++i)
 522		t->sighand->action[i].sa.sa_handler = SIG_IGN;
 523
 524	flush_signals(t);
 525}
 526
 527/*
 528 * Flush all handlers for a task.
 529 */
 530
 531void
 532flush_signal_handlers(struct task_struct *t, int force_default)
 533{
 534	int i;
 535	struct k_sigaction *ka = &t->sighand->action[0];
 536	for (i = _NSIG ; i != 0 ; i--) {
 537		if (force_default || ka->sa.sa_handler != SIG_IGN)
 538			ka->sa.sa_handler = SIG_DFL;
 539		ka->sa.sa_flags = 0;
 540#ifdef __ARCH_HAS_SA_RESTORER
 541		ka->sa.sa_restorer = NULL;
 542#endif
 543		sigemptyset(&ka->sa.sa_mask);
 544		ka++;
 545	}
 546}
 547
 548bool unhandled_signal(struct task_struct *tsk, int sig)
 549{
 550	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
 551	if (is_global_init(tsk))
 552		return true;
 553
 554	if (handler != SIG_IGN && handler != SIG_DFL)
 555		return false;
 556
 557	/* If dying, we handle all new signals by ignoring them */
 558	if (fatal_signal_pending(tsk))
 559		return false;
 560
 561	/* if ptraced, let the tracer determine */
 562	return !tsk->ptrace;
 563}
 564
 565static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info,
 566			   bool *resched_timer)
 567{
 568	struct sigqueue *q, *first = NULL;
 569
 570	/*
 571	 * Collect the siginfo appropriate to this signal.  Check if
 572	 * there is another siginfo for the same signal.
 573	*/
 574	list_for_each_entry(q, &list->list, list) {
 575		if (q->info.si_signo == sig) {
 576			if (first)
 577				goto still_pending;
 578			first = q;
 579		}
 580	}
 581
 582	sigdelset(&list->signal, sig);
 583
 584	if (first) {
 585still_pending:
 586		list_del_init(&first->list);
 587		copy_siginfo(info, &first->info);
 588
 589		*resched_timer =
 590			(first->flags & SIGQUEUE_PREALLOC) &&
 591			(info->si_code == SI_TIMER) &&
 592			(info->si_sys_private);
 593
 594		__sigqueue_free(first);
 595	} else {
 596		/*
 597		 * Ok, it wasn't in the queue.  This must be
 598		 * a fast-pathed signal or we must have been
 599		 * out of queue space.  So zero out the info.
 600		 */
 601		clear_siginfo(info);
 602		info->si_signo = sig;
 603		info->si_errno = 0;
 604		info->si_code = SI_USER;
 605		info->si_pid = 0;
 606		info->si_uid = 0;
 607	}
 608}
 609
 610static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
 611			kernel_siginfo_t *info, bool *resched_timer)
 612{
 613	int sig = next_signal(pending, mask);
 614
 615	if (sig)
 616		collect_signal(sig, pending, info, resched_timer);
 617	return sig;
 618}
 619
 620/*
 621 * Dequeue a signal and return the element to the caller, which is
 622 * expected to free it.
 623 *
 624 * All callers have to hold the siglock.
 625 */
 626int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
 627		   kernel_siginfo_t *info, enum pid_type *type)
 628{
 629	bool resched_timer = false;
 630	int signr;
 631
 632	/* We only dequeue private signals from ourselves, we don't let
 633	 * signalfd steal them
 634	 */
 635	*type = PIDTYPE_PID;
 636	signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
 637	if (!signr) {
 638		*type = PIDTYPE_TGID;
 639		signr = __dequeue_signal(&tsk->signal->shared_pending,
 640					 mask, info, &resched_timer);
 641#ifdef CONFIG_POSIX_TIMERS
 642		/*
 643		 * itimer signal ?
 644		 *
 645		 * itimers are process shared and we restart periodic
 646		 * itimers in the signal delivery path to prevent DoS
 647		 * attacks in the high resolution timer case. This is
 648		 * compliant with the old way of self-restarting
 649		 * itimers, as the SIGALRM is a legacy signal and only
 650		 * queued once. Changing the restart behaviour to
 651		 * restart the timer in the signal dequeue path is
 652		 * reducing the timer noise on heavy loaded !highres
 653		 * systems too.
 654		 */
 655		if (unlikely(signr == SIGALRM)) {
 656			struct hrtimer *tmr = &tsk->signal->real_timer;
 657
 658			if (!hrtimer_is_queued(tmr) &&
 659			    tsk->signal->it_real_incr != 0) {
 660				hrtimer_forward(tmr, tmr->base->get_time(),
 661						tsk->signal->it_real_incr);
 662				hrtimer_restart(tmr);
 663			}
 664		}
 665#endif
 666	}
 667
 668	recalc_sigpending();
 669	if (!signr)
 670		return 0;
 671
 672	if (unlikely(sig_kernel_stop(signr))) {
 673		/*
 674		 * Set a marker that we have dequeued a stop signal.  Our
 675		 * caller might release the siglock and then the pending
 676		 * stop signal it is about to process is no longer in the
 677		 * pending bitmasks, but must still be cleared by a SIGCONT
 678		 * (and overruled by a SIGKILL).  So those cases clear this
 679		 * shared flag after we've set it.  Note that this flag may
 680		 * remain set after the signal we return is ignored or
 681		 * handled.  That doesn't matter because its only purpose
 682		 * is to alert stop-signal processing code when another
 683		 * processor has come along and cleared the flag.
 684		 */
 685		current->jobctl |= JOBCTL_STOP_DEQUEUED;
 686	}
 687#ifdef CONFIG_POSIX_TIMERS
 688	if (resched_timer) {
 689		/*
 690		 * Release the siglock to ensure proper locking order
 691		 * of timer locks outside of siglocks.  Note, we leave
 692		 * irqs disabled here, since the posix-timers code is
 693		 * about to disable them again anyway.
 694		 */
 695		spin_unlock(&tsk->sighand->siglock);
 696		posixtimer_rearm(info);
 697		spin_lock(&tsk->sighand->siglock);
 698
 699		/* Don't expose the si_sys_private value to userspace */
 700		info->si_sys_private = 0;
 701	}
 702#endif
 703	return signr;
 704}
 705EXPORT_SYMBOL_GPL(dequeue_signal);
 706
 707static int dequeue_synchronous_signal(kernel_siginfo_t *info)
 708{
 709	struct task_struct *tsk = current;
 710	struct sigpending *pending = &tsk->pending;
 711	struct sigqueue *q, *sync = NULL;
 712
 713	/*
 714	 * Might a synchronous signal be in the queue?
 715	 */
 716	if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK))
 717		return 0;
 718
 719	/*
 720	 * Return the first synchronous signal in the queue.
 721	 */
 722	list_for_each_entry(q, &pending->list, list) {
 723		/* Synchronous signals have a positive si_code */
 724		if ((q->info.si_code > SI_USER) &&
 725		    (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) {
 726			sync = q;
 727			goto next;
 728		}
 729	}
 730	return 0;
 731next:
 732	/*
 733	 * Check if there is another siginfo for the same signal.
 734	 */
 735	list_for_each_entry_continue(q, &pending->list, list) {
 736		if (q->info.si_signo == sync->info.si_signo)
 737			goto still_pending;
 738	}
 739
 740	sigdelset(&pending->signal, sync->info.si_signo);
 741	recalc_sigpending();
 742still_pending:
 743	list_del_init(&sync->list);
 744	copy_siginfo(info, &sync->info);
 745	__sigqueue_free(sync);
 746	return info->si_signo;
 747}
 748
 749/*
 750 * Tell a process that it has a new active signal..
 751 *
 752 * NOTE! we rely on the previous spin_lock to
 753 * lock interrupts for us! We can only be called with
 754 * "siglock" held, and the local interrupt must
 755 * have been disabled when that got acquired!
 756 *
 757 * No need to set need_resched since signal event passing
 758 * goes through ->blocked
 759 */
 760void signal_wake_up_state(struct task_struct *t, unsigned int state)
 761{
 762	lockdep_assert_held(&t->sighand->siglock);
 763
 764	set_tsk_thread_flag(t, TIF_SIGPENDING);
 765
 766	/*
 767	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
 768	 * case. We don't check t->state here because there is a race with it
 769	 * executing another processor and just now entering stopped state.
 770	 * By using wake_up_state, we ensure the process will wake up and
 771	 * handle its death signal.
 772	 */
 773	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
 774		kick_process(t);
 775}
 776
 777/*
 778 * Remove signals in mask from the pending set and queue.
 779 * Returns 1 if any signals were found.
 780 *
 781 * All callers must be holding the siglock.
 782 */
 783static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
 784{
 785	struct sigqueue *q, *n;
 786	sigset_t m;
 787
 788	sigandsets(&m, mask, &s->signal);
 789	if (sigisemptyset(&m))
 790		return;
 791
 792	sigandnsets(&s->signal, &s->signal, mask);
 793	list_for_each_entry_safe(q, n, &s->list, list) {
 794		if (sigismember(mask, q->info.si_signo)) {
 795			list_del_init(&q->list);
 796			__sigqueue_free(q);
 797		}
 798	}
 
 799}
 800
 801static inline int is_si_special(const struct kernel_siginfo *info)
 802{
 803	return info <= SEND_SIG_PRIV;
 804}
 805
 806static inline bool si_fromuser(const struct kernel_siginfo *info)
 807{
 808	return info == SEND_SIG_NOINFO ||
 809		(!is_si_special(info) && SI_FROMUSER(info));
 810}
 811
 812/*
 813 * called with RCU read lock from check_kill_permission()
 814 */
 815static bool kill_ok_by_cred(struct task_struct *t)
 816{
 817	const struct cred *cred = current_cred();
 818	const struct cred *tcred = __task_cred(t);
 819
 820	return uid_eq(cred->euid, tcred->suid) ||
 821	       uid_eq(cred->euid, tcred->uid) ||
 822	       uid_eq(cred->uid, tcred->suid) ||
 823	       uid_eq(cred->uid, tcred->uid) ||
 824	       ns_capable(tcred->user_ns, CAP_KILL);
 
 
 
 
 
 825}
 826
 827/*
 828 * Bad permissions for sending the signal
 829 * - the caller must hold the RCU read lock
 830 */
 831static int check_kill_permission(int sig, struct kernel_siginfo *info,
 832				 struct task_struct *t)
 833{
 834	struct pid *sid;
 835	int error;
 836
 837	if (!valid_signal(sig))
 838		return -EINVAL;
 839
 840	if (!si_fromuser(info))
 841		return 0;
 842
 843	error = audit_signal_info(sig, t); /* Let audit system see the signal */
 844	if (error)
 845		return error;
 846
 847	if (!same_thread_group(current, t) &&
 848	    !kill_ok_by_cred(t)) {
 849		switch (sig) {
 850		case SIGCONT:
 851			sid = task_session(t);
 852			/*
 853			 * We don't return the error if sid == NULL. The
 854			 * task was unhashed, the caller must notice this.
 855			 */
 856			if (!sid || sid == task_session(current))
 857				break;
 858			fallthrough;
 859		default:
 860			return -EPERM;
 861		}
 862	}
 863
 864	return security_task_kill(t, info, sig, NULL);
 865}
 866
 867/**
 868 * ptrace_trap_notify - schedule trap to notify ptracer
 869 * @t: tracee wanting to notify tracer
 870 *
 871 * This function schedules sticky ptrace trap which is cleared on the next
 872 * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
 873 * ptracer.
 874 *
 875 * If @t is running, STOP trap will be taken.  If trapped for STOP and
 876 * ptracer is listening for events, tracee is woken up so that it can
 877 * re-trap for the new event.  If trapped otherwise, STOP trap will be
 878 * eventually taken without returning to userland after the existing traps
 879 * are finished by PTRACE_CONT.
 880 *
 881 * CONTEXT:
 882 * Must be called with @task->sighand->siglock held.
 883 */
 884static void ptrace_trap_notify(struct task_struct *t)
 885{
 886	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
 887	lockdep_assert_held(&t->sighand->siglock);
 888
 889	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
 890	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
 891}
 892
 893/*
 894 * Handle magic process-wide effects of stop/continue signals. Unlike
 895 * the signal actions, these happen immediately at signal-generation
 896 * time regardless of blocking, ignoring, or handling.  This does the
 897 * actual continuing for SIGCONT, but not the actual stopping for stop
 898 * signals. The process stop is done as a signal action for SIG_DFL.
 899 *
 900 * Returns true if the signal should be actually delivered, otherwise
 901 * it should be dropped.
 902 */
 903static bool prepare_signal(int sig, struct task_struct *p, bool force)
 904{
 905	struct signal_struct *signal = p->signal;
 906	struct task_struct *t;
 907	sigset_t flush;
 908
 909	if (signal->flags & SIGNAL_GROUP_EXIT) {
 910		if (signal->core_state)
 911			return sig == SIGKILL;
 912		/*
 913		 * The process is in the middle of dying, drop the signal.
 914		 */
 915		return false;
 916	} else if (sig_kernel_stop(sig)) {
 917		/*
 918		 * This is a stop signal.  Remove SIGCONT from all queues.
 919		 */
 920		siginitset(&flush, sigmask(SIGCONT));
 921		flush_sigqueue_mask(&flush, &signal->shared_pending);
 922		for_each_thread(p, t)
 923			flush_sigqueue_mask(&flush, &t->pending);
 924	} else if (sig == SIGCONT) {
 925		unsigned int why;
 926		/*
 927		 * Remove all stop signals from all queues, wake all threads.
 928		 */
 929		siginitset(&flush, SIG_KERNEL_STOP_MASK);
 930		flush_sigqueue_mask(&flush, &signal->shared_pending);
 931		for_each_thread(p, t) {
 932			flush_sigqueue_mask(&flush, &t->pending);
 933			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
 934			if (likely(!(t->ptrace & PT_SEIZED))) {
 935				t->jobctl &= ~JOBCTL_STOPPED;
 936				wake_up_state(t, __TASK_STOPPED);
 937			} else
 938				ptrace_trap_notify(t);
 939		}
 940
 941		/*
 942		 * Notify the parent with CLD_CONTINUED if we were stopped.
 943		 *
 944		 * If we were in the middle of a group stop, we pretend it
 945		 * was already finished, and then continued. Since SIGCHLD
 946		 * doesn't queue we report only CLD_STOPPED, as if the next
 947		 * CLD_CONTINUED was dropped.
 948		 */
 949		why = 0;
 950		if (signal->flags & SIGNAL_STOP_STOPPED)
 951			why |= SIGNAL_CLD_CONTINUED;
 952		else if (signal->group_stop_count)
 953			why |= SIGNAL_CLD_STOPPED;
 954
 955		if (why) {
 956			/*
 957			 * The first thread which returns from do_signal_stop()
 958			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
 959			 * notify its parent. See get_signal().
 960			 */
 961			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
 962			signal->group_stop_count = 0;
 963			signal->group_exit_code = 0;
 964		}
 965	}
 966
 967	return !sig_ignored(p, sig, force);
 968}
 969
 970/*
 971 * Test if P wants to take SIG.  After we've checked all threads with this,
 972 * it's equivalent to finding no threads not blocking SIG.  Any threads not
 973 * blocking SIG were ruled out because they are not running and already
 974 * have pending signals.  Such threads will dequeue from the shared queue
 975 * as soon as they're available, so putting the signal on the shared queue
 976 * will be equivalent to sending it to one such thread.
 977 */
 978static inline bool wants_signal(int sig, struct task_struct *p)
 979{
 980	if (sigismember(&p->blocked, sig))
 981		return false;
 982
 983	if (p->flags & PF_EXITING)
 984		return false;
 985
 986	if (sig == SIGKILL)
 987		return true;
 988
 989	if (task_is_stopped_or_traced(p))
 990		return false;
 991
 992	return task_curr(p) || !task_sigpending(p);
 993}
 994
 995static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
 996{
 997	struct signal_struct *signal = p->signal;
 998	struct task_struct *t;
 999
1000	/*
1001	 * Now find a thread we can wake up to take the signal off the queue.
1002	 *
1003	 * Try the suggested task first (may or may not be the main thread).
 
1004	 */
1005	if (wants_signal(sig, p))
1006		t = p;
1007	else if ((type == PIDTYPE_PID) || thread_group_empty(p))
1008		/*
1009		 * There is just one thread and it does not need to be woken.
1010		 * It will dequeue unblocked signals before it runs again.
1011		 */
1012		return;
1013	else {
1014		/*
1015		 * Otherwise try to find a suitable thread.
1016		 */
1017		t = signal->curr_target;
1018		while (!wants_signal(sig, t)) {
1019			t = next_thread(t);
1020			if (t == signal->curr_target)
1021				/*
1022				 * No thread needs to be woken.
1023				 * Any eligible threads will see
1024				 * the signal in the queue soon.
1025				 */
1026				return;
1027		}
1028		signal->curr_target = t;
1029	}
1030
1031	/*
1032	 * Found a killable thread.  If the signal will be fatal,
1033	 * then start taking the whole group down immediately.
1034	 */
1035	if (sig_fatal(p, sig) &&
1036	    (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
1037	    !sigismember(&t->real_blocked, sig) &&
1038	    (sig == SIGKILL || !p->ptrace)) {
1039		/*
1040		 * This signal will be fatal to the whole group.
1041		 */
1042		if (!sig_kernel_coredump(sig)) {
1043			/*
1044			 * Start a group exit and wake everybody up.
1045			 * This way we don't have other threads
1046			 * running and doing things after a slower
1047			 * thread has the fatal signal pending.
1048			 */
1049			signal->flags = SIGNAL_GROUP_EXIT;
1050			signal->group_exit_code = sig;
1051			signal->group_stop_count = 0;
1052			__for_each_thread(signal, t) {
 
1053				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1054				sigaddset(&t->pending.signal, SIGKILL);
1055				signal_wake_up(t, 1);
1056			}
1057			return;
1058		}
1059	}
1060
1061	/*
1062	 * The signal is already in the shared-pending queue.
1063	 * Tell the chosen thread to wake up and dequeue it.
1064	 */
1065	signal_wake_up(t, sig == SIGKILL);
1066	return;
1067}
1068
1069static inline bool legacy_queue(struct sigpending *signals, int sig)
1070{
1071	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
1072}
1073
1074static int __send_signal_locked(int sig, struct kernel_siginfo *info,
1075				struct task_struct *t, enum pid_type type, bool force)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1076{
1077	struct sigpending *pending;
1078	struct sigqueue *q;
1079	int override_rlimit;
1080	int ret = 0, result;
1081
1082	lockdep_assert_held(&t->sighand->siglock);
1083
1084	result = TRACE_SIGNAL_IGNORED;
1085	if (!prepare_signal(sig, t, force))
 
1086		goto ret;
1087
1088	pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
1089	/*
1090	 * Short-circuit ignored signals and support queuing
1091	 * exactly one non-rt signal, so that we can get more
1092	 * detailed information about the cause of the signal.
1093	 */
1094	result = TRACE_SIGNAL_ALREADY_PENDING;
1095	if (legacy_queue(pending, sig))
1096		goto ret;
1097
1098	result = TRACE_SIGNAL_DELIVERED;
1099	/*
1100	 * Skip useless siginfo allocation for SIGKILL and kernel threads.
 
1101	 */
1102	if ((sig == SIGKILL) || (t->flags & PF_KTHREAD))
1103		goto out_set;
1104
1105	/*
1106	 * Real-time signals must be queued if sent by sigqueue, or
1107	 * some other real-time mechanism.  It is implementation
1108	 * defined whether kill() does so.  We attempt to do so, on
1109	 * the principle of least surprise, but since kill is not
1110	 * allowed to fail with EAGAIN when low on memory we just
1111	 * make sure at least one signal gets delivered and don't
1112	 * pass on the info struct.
1113	 */
1114	if (sig < SIGRTMIN)
1115		override_rlimit = (is_si_special(info) || info->si_code >= 0);
1116	else
1117		override_rlimit = 0;
1118
1119	q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0);
1120
1121	if (q) {
1122		list_add_tail(&q->list, &pending->list);
1123		switch ((unsigned long) info) {
1124		case (unsigned long) SEND_SIG_NOINFO:
1125			clear_siginfo(&q->info);
1126			q->info.si_signo = sig;
1127			q->info.si_errno = 0;
1128			q->info.si_code = SI_USER;
1129			q->info.si_pid = task_tgid_nr_ns(current,
1130							task_active_pid_ns(t));
1131			rcu_read_lock();
1132			q->info.si_uid =
1133				from_kuid_munged(task_cred_xxx(t, user_ns),
1134						 current_uid());
1135			rcu_read_unlock();
1136			break;
1137		case (unsigned long) SEND_SIG_PRIV:
1138			clear_siginfo(&q->info);
1139			q->info.si_signo = sig;
1140			q->info.si_errno = 0;
1141			q->info.si_code = SI_KERNEL;
1142			q->info.si_pid = 0;
1143			q->info.si_uid = 0;
1144			break;
1145		default:
1146			copy_siginfo(&q->info, info);
 
 
1147			break;
1148		}
1149	} else if (!is_si_special(info) &&
1150		   sig >= SIGRTMIN && info->si_code != SI_USER) {
1151		/*
1152		 * Queue overflow, abort.  We may abort if the
1153		 * signal was rt and sent by user using something
1154		 * other than kill().
1155		 */
1156		result = TRACE_SIGNAL_OVERFLOW_FAIL;
1157		ret = -EAGAIN;
1158		goto ret;
1159	} else {
1160		/*
1161		 * This is a silent loss of information.  We still
1162		 * send the signal, but the *info bits are lost.
1163		 */
1164		result = TRACE_SIGNAL_LOSE_INFO;
 
 
 
 
1165	}
1166
1167out_set:
1168	signalfd_notify(t, sig);
1169	sigaddset(&pending->signal, sig);
1170
1171	/* Let multiprocess signals appear after on-going forks */
1172	if (type > PIDTYPE_TGID) {
1173		struct multiprocess_signals *delayed;
1174		hlist_for_each_entry(delayed, &t->signal->multiprocess, node) {
1175			sigset_t *signal = &delayed->signal;
1176			/* Can't queue both a stop and a continue signal */
1177			if (sig == SIGCONT)
1178				sigdelsetmask(signal, SIG_KERNEL_STOP_MASK);
1179			else if (sig_kernel_stop(sig))
1180				sigdelset(signal, SIGCONT);
1181			sigaddset(signal, sig);
1182		}
1183	}
1184
1185	complete_signal(sig, t, type);
1186ret:
1187	trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result);
1188	return ret;
1189}
1190
1191static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
1192{
1193	bool ret = false;
1194	switch (siginfo_layout(info->si_signo, info->si_code)) {
1195	case SIL_KILL:
1196	case SIL_CHLD:
1197	case SIL_RT:
1198		ret = true;
1199		break;
1200	case SIL_TIMER:
1201	case SIL_POLL:
1202	case SIL_FAULT:
1203	case SIL_FAULT_TRAPNO:
1204	case SIL_FAULT_MCEERR:
1205	case SIL_FAULT_BNDERR:
1206	case SIL_FAULT_PKUERR:
1207	case SIL_FAULT_PERF_EVENT:
1208	case SIL_SYS:
1209		ret = false;
1210		break;
1211	}
1212	return ret;
1213}
1214
1215int send_signal_locked(int sig, struct kernel_siginfo *info,
1216		       struct task_struct *t, enum pid_type type)
1217{
1218	/* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
1219	bool force = false;
1220
1221	if (info == SEND_SIG_NOINFO) {
1222		/* Force if sent from an ancestor pid namespace */
1223		force = !task_pid_nr_ns(current, task_active_pid_ns(t));
1224	} else if (info == SEND_SIG_PRIV) {
1225		/* Don't ignore kernel generated signals */
1226		force = true;
1227	} else if (has_si_pid_and_uid(info)) {
1228		/* SIGKILL and SIGSTOP is special or has ids */
1229		struct user_namespace *t_user_ns;
1230
1231		rcu_read_lock();
1232		t_user_ns = task_cred_xxx(t, user_ns);
1233		if (current_user_ns() != t_user_ns) {
1234			kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
1235			info->si_uid = from_kuid_munged(t_user_ns, uid);
1236		}
1237		rcu_read_unlock();
1238
1239		/* A kernel generated signal? */
1240		force = (info->si_code == SI_KERNEL);
1241
1242		/* From an ancestor pid namespace? */
1243		if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
1244			info->si_pid = 0;
1245			force = true;
1246		}
1247	}
1248	return __send_signal_locked(sig, info, t, type, force);
1249}
1250
1251static void print_fatal_signal(int signr)
1252{
1253	struct pt_regs *regs = task_pt_regs(current);
1254	struct file *exe_file;
1255
1256	exe_file = get_task_exe_file(current);
1257	if (exe_file) {
1258		pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
1259			exe_file, current->comm, signr);
1260		fput(exe_file);
1261	} else {
1262		pr_info("%s: potentially unexpected fatal signal %d.\n",
1263			current->comm, signr);
1264	}
1265
1266#if defined(__i386__) && !defined(__arch_um__)
1267	pr_info("code at %08lx: ", regs->ip);
1268	{
1269		int i;
1270		for (i = 0; i < 16; i++) {
1271			unsigned char insn;
1272
1273			if (get_user(insn, (unsigned char *)(regs->ip + i)))
1274				break;
1275			pr_cont("%02x ", insn);
1276		}
1277	}
1278	pr_cont("\n");
1279#endif
1280	preempt_disable();
1281	show_regs(regs);
1282	preempt_enable();
1283}
1284
1285static int __init setup_print_fatal_signals(char *str)
1286{
1287	get_option (&str, &print_fatal_signals);
1288
1289	return 1;
1290}
1291
1292__setup("print-fatal-signals=", setup_print_fatal_signals);
1293
1294int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p,
1295			enum pid_type type)
 
 
 
 
 
 
 
 
 
 
 
 
1296{
1297	unsigned long flags;
1298	int ret = -ESRCH;
1299
1300	if (lock_task_sighand(p, &flags)) {
1301		ret = send_signal_locked(sig, info, p, type);
1302		unlock_task_sighand(p, &flags);
1303	}
1304
1305	return ret;
1306}
1307
1308enum sig_handler {
1309	HANDLER_CURRENT, /* If reachable use the current handler */
1310	HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
1311	HANDLER_EXIT,	 /* Only visible as the process exit code */
1312};
1313
1314/*
1315 * Force a signal that the process can't ignore: if necessary
1316 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1317 *
1318 * Note: If we unblock the signal, we always reset it to SIG_DFL,
1319 * since we do not want to have a signal handler that was blocked
1320 * be invoked when user space had explicitly blocked it.
1321 *
1322 * We don't want to have recursive SIGSEGV's etc, for example,
1323 * that is why we also clear SIGNAL_UNKILLABLE.
1324 */
1325static int
1326force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
1327	enum sig_handler handler)
1328{
1329	unsigned long int flags;
1330	int ret, blocked, ignored;
1331	struct k_sigaction *action;
1332	int sig = info->si_signo;
1333
1334	spin_lock_irqsave(&t->sighand->siglock, flags);
1335	action = &t->sighand->action[sig-1];
1336	ignored = action->sa.sa_handler == SIG_IGN;
1337	blocked = sigismember(&t->blocked, sig);
1338	if (blocked || ignored || (handler != HANDLER_CURRENT)) {
1339		action->sa.sa_handler = SIG_DFL;
1340		if (handler == HANDLER_EXIT)
1341			action->sa.sa_flags |= SA_IMMUTABLE;
1342		if (blocked)
1343			sigdelset(&t->blocked, sig);
 
 
1344	}
1345	/*
1346	 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
1347	 * debugging to leave init killable. But HANDLER_EXIT is always fatal.
1348	 */
1349	if (action->sa.sa_handler == SIG_DFL &&
1350	    (!t->ptrace || (handler == HANDLER_EXIT)))
1351		t->signal->flags &= ~SIGNAL_UNKILLABLE;
1352	ret = send_signal_locked(sig, info, t, PIDTYPE_PID);
1353	/* This can happen if the signal was already pending and blocked */
1354	if (!task_sigpending(t))
1355		signal_wake_up(t, 0);
1356	spin_unlock_irqrestore(&t->sighand->siglock, flags);
1357
1358	return ret;
1359}
1360
1361int force_sig_info(struct kernel_siginfo *info)
1362{
1363	return force_sig_info_to_task(info, current, HANDLER_CURRENT);
1364}
1365
1366/*
1367 * Nuke all other threads in the group.
1368 */
1369int zap_other_threads(struct task_struct *p)
1370{
1371	struct task_struct *t;
1372	int count = 0;
1373
1374	p->signal->group_stop_count = 0;
1375
1376	for_other_threads(p, t) {
1377		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1378		/* Don't require de_thread to wait for the vhost_worker */
1379		if ((t->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)
1380			count++;
1381
1382		/* Don't bother with already dead threads */
1383		if (t->exit_state)
1384			continue;
1385		sigaddset(&t->pending.signal, SIGKILL);
1386		signal_wake_up(t, 1);
1387	}
1388
1389	return count;
1390}
1391
1392struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
1393					   unsigned long *flags)
1394{
1395	struct sighand_struct *sighand;
1396
1397	rcu_read_lock();
1398	for (;;) {
 
 
 
 
 
 
1399		sighand = rcu_dereference(tsk->sighand);
1400		if (unlikely(sighand == NULL))
 
 
1401			break;
1402
1403		/*
1404		 * This sighand can be already freed and even reused, but
1405		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1406		 * initializes ->siglock: this slab can't go away, it has
1407		 * the same object type, ->siglock can't be reinitialized.
1408		 *
1409		 * We need to ensure that tsk->sighand is still the same
1410		 * after we take the lock, we can race with de_thread() or
1411		 * __exit_signal(). In the latter case the next iteration
1412		 * must see ->sighand == NULL.
1413		 */
1414		spin_lock_irqsave(&sighand->siglock, *flags);
1415		if (likely(sighand == rcu_access_pointer(tsk->sighand)))
 
1416			break;
1417		spin_unlock_irqrestore(&sighand->siglock, *flags);
 
 
 
1418	}
1419	rcu_read_unlock();
1420
1421	return sighand;
1422}
1423
1424#ifdef CONFIG_LOCKDEP
1425void lockdep_assert_task_sighand_held(struct task_struct *task)
1426{
1427	struct sighand_struct *sighand;
1428
1429	rcu_read_lock();
1430	sighand = rcu_dereference(task->sighand);
1431	if (sighand)
1432		lockdep_assert_held(&sighand->siglock);
1433	else
1434		WARN_ON_ONCE(1);
1435	rcu_read_unlock();
1436}
1437#endif
1438
1439/*
1440 * send signal info to all the members of a thread group or to the
1441 * individual thread if type == PIDTYPE_PID.
1442 */
1443int group_send_sig_info(int sig, struct kernel_siginfo *info,
1444			struct task_struct *p, enum pid_type type)
1445{
1446	int ret;
1447
1448	rcu_read_lock();
1449	ret = check_kill_permission(sig, info, p);
1450	rcu_read_unlock();
1451
1452	if (!ret && sig)
1453		ret = do_send_sig_info(sig, info, p, type);
1454
1455	return ret;
1456}
1457
1458/*
1459 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
1460 * control characters do (^C, ^Z etc)
1461 * - the caller must hold at least a readlock on tasklist_lock
1462 */
1463int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1464{
1465	struct task_struct *p = NULL;
1466	int ret = -ESRCH;
1467
 
 
1468	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
1469		int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID);
1470		/*
1471		 * If group_send_sig_info() succeeds at least once ret
1472		 * becomes 0 and after that the code below has no effect.
1473		 * Otherwise we return the last err or -ESRCH if this
1474		 * process group is empty.
1475		 */
1476		if (ret)
1477			ret = err;
1478	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1479
1480	return ret;
1481}
1482
1483static int kill_pid_info_type(int sig, struct kernel_siginfo *info,
1484				struct pid *pid, enum pid_type type)
1485{
1486	int error = -ESRCH;
1487	struct task_struct *p;
1488
1489	for (;;) {
1490		rcu_read_lock();
1491		p = pid_task(pid, PIDTYPE_PID);
1492		if (p)
1493			error = group_send_sig_info(sig, info, p, type);
1494		rcu_read_unlock();
1495		if (likely(!p || error != -ESRCH))
1496			return error;
 
1497		/*
1498		 * The task was unhashed in between, try again.  If it
1499		 * is dead, pid_task() will return NULL, if we race with
1500		 * de_thread() it will find the new leader.
1501		 */
1502	}
1503}
1504
1505int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid)
1506{
1507	return kill_pid_info_type(sig, info, pid, PIDTYPE_TGID);
1508}
1509
1510static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid)
1511{
1512	int error;
1513	rcu_read_lock();
1514	error = kill_pid_info(sig, info, find_vpid(pid));
1515	rcu_read_unlock();
1516	return error;
1517}
1518
1519static inline bool kill_as_cred_perm(const struct cred *cred,
1520				     struct task_struct *target)
1521{
1522	const struct cred *pcred = __task_cred(target);
1523
1524	return uid_eq(cred->euid, pcred->suid) ||
1525	       uid_eq(cred->euid, pcred->uid) ||
1526	       uid_eq(cred->uid, pcred->suid) ||
1527	       uid_eq(cred->uid, pcred->uid);
1528}
1529
1530/*
1531 * The usb asyncio usage of siginfo is wrong.  The glibc support
1532 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
1533 * AKA after the generic fields:
1534 *	kernel_pid_t	si_pid;
1535 *	kernel_uid32_t	si_uid;
1536 *	sigval_t	si_value;
1537 *
1538 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
1539 * after the generic fields is:
1540 *	void __user 	*si_addr;
1541 *
1542 * This is a practical problem when there is a 64bit big endian kernel
1543 * and a 32bit userspace.  As the 32bit address will encoded in the low
1544 * 32bits of the pointer.  Those low 32bits will be stored at higher
1545 * address than appear in a 32 bit pointer.  So userspace will not
1546 * see the address it was expecting for it's completions.
1547 *
1548 * There is nothing in the encoding that can allow
1549 * copy_siginfo_to_user32 to detect this confusion of formats, so
1550 * handle this by requiring the caller of kill_pid_usb_asyncio to
1551 * notice when this situration takes place and to store the 32bit
1552 * pointer in sival_int, instead of sival_addr of the sigval_t addr
1553 * parameter.
1554 */
1555int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
1556			 struct pid *pid, const struct cred *cred)
1557{
1558	struct kernel_siginfo info;
1559	struct task_struct *p;
1560	unsigned long flags;
1561	int ret = -EINVAL;
1562
1563	if (!valid_signal(sig))
1564		return ret;
1565
1566	clear_siginfo(&info);
1567	info.si_signo = sig;
1568	info.si_errno = errno;
1569	info.si_code = SI_ASYNCIO;
1570	*((sigval_t *)&info.si_pid) = addr;
1571
1572	rcu_read_lock();
1573	p = pid_task(pid, PIDTYPE_PID);
1574	if (!p) {
1575		ret = -ESRCH;
1576		goto out_unlock;
1577	}
1578	if (!kill_as_cred_perm(cred, p)) {
1579		ret = -EPERM;
1580		goto out_unlock;
1581	}
1582	ret = security_task_kill(p, &info, sig, cred);
1583	if (ret)
1584		goto out_unlock;
1585
1586	if (sig) {
1587		if (lock_task_sighand(p, &flags)) {
1588			ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false);
1589			unlock_task_sighand(p, &flags);
1590		} else
1591			ret = -ESRCH;
1592	}
1593out_unlock:
1594	rcu_read_unlock();
1595	return ret;
1596}
1597EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
1598
1599/*
1600 * kill_something_info() interprets pid in interesting ways just like kill(2).
1601 *
1602 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1603 * is probably wrong.  Should make it like BSD or SYSV.
1604 */
1605
1606static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
1607{
1608	int ret;
1609
1610	if (pid > 0)
1611		return kill_proc_info(sig, info, pid);
 
 
 
 
1612
1613	/* -INT_MIN is undefined.  Exclude this case to avoid a UBSAN warning */
1614	if (pid == INT_MIN)
1615		return -ESRCH;
1616
1617	read_lock(&tasklist_lock);
1618	if (pid != -1) {
1619		ret = __kill_pgrp_info(sig, info,
1620				pid ? find_vpid(-pid) : task_pgrp(current));
1621	} else {
1622		int retval = 0, count = 0;
1623		struct task_struct * p;
1624
1625		for_each_process(p) {
1626			if (task_pid_vnr(p) > 1 &&
1627					!same_thread_group(p, current)) {
1628				int err = group_send_sig_info(sig, info, p,
1629							      PIDTYPE_MAX);
1630				++count;
1631				if (err != -EPERM)
1632					retval = err;
1633			}
1634		}
1635		ret = count ? retval : -ESRCH;
1636	}
1637	read_unlock(&tasklist_lock);
1638
1639	return ret;
1640}
1641
1642/*
1643 * These are for backward compatibility with the rest of the kernel source.
1644 */
1645
1646int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p)
1647{
1648	/*
1649	 * Make sure legacy kernel users don't send in bad values
1650	 * (normal paths check this in check_kill_permission).
1651	 */
1652	if (!valid_signal(sig))
1653		return -EINVAL;
1654
1655	return do_send_sig_info(sig, info, p, PIDTYPE_PID);
1656}
1657EXPORT_SYMBOL(send_sig_info);
1658
1659#define __si_special(priv) \
1660	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1661
1662int
1663send_sig(int sig, struct task_struct *p, int priv)
1664{
1665	return send_sig_info(sig, __si_special(priv), p);
1666}
1667EXPORT_SYMBOL(send_sig);
1668
1669void force_sig(int sig)
1670{
1671	struct kernel_siginfo info;
1672
1673	clear_siginfo(&info);
1674	info.si_signo = sig;
1675	info.si_errno = 0;
1676	info.si_code = SI_KERNEL;
1677	info.si_pid = 0;
1678	info.si_uid = 0;
1679	force_sig_info(&info);
1680}
1681EXPORT_SYMBOL(force_sig);
1682
1683void force_fatal_sig(int sig)
1684{
1685	struct kernel_siginfo info;
1686
1687	clear_siginfo(&info);
1688	info.si_signo = sig;
1689	info.si_errno = 0;
1690	info.si_code = SI_KERNEL;
1691	info.si_pid = 0;
1692	info.si_uid = 0;
1693	force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
1694}
1695
1696void force_exit_sig(int sig)
1697{
1698	struct kernel_siginfo info;
1699
1700	clear_siginfo(&info);
1701	info.si_signo = sig;
1702	info.si_errno = 0;
1703	info.si_code = SI_KERNEL;
1704	info.si_pid = 0;
1705	info.si_uid = 0;
1706	force_sig_info_to_task(&info, current, HANDLER_EXIT);
1707}
1708
1709/*
1710 * When things go south during signal handling, we
1711 * will force a SIGSEGV. And if the signal that caused
1712 * the problem was already a SIGSEGV, we'll want to
1713 * make sure we don't even try to deliver the signal..
1714 */
1715void force_sigsegv(int sig)
 
1716{
1717	if (sig == SIGSEGV)
1718		force_fatal_sig(SIGSEGV);
1719	else
1720		force_sig(SIGSEGV);
 
 
 
 
1721}
1722
1723int force_sig_fault_to_task(int sig, int code, void __user *addr,
1724			    struct task_struct *t)
 
 
1725{
1726	struct kernel_siginfo info;
1727
1728	clear_siginfo(&info);
1729	info.si_signo = sig;
1730	info.si_errno = 0;
1731	info.si_code  = code;
1732	info.si_addr  = addr;
1733	return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
1734}
1735
1736int force_sig_fault(int sig, int code, void __user *addr)
1737{
1738	return force_sig_fault_to_task(sig, code, addr, current);
 
 
 
1739}
1740
1741int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t)
 
 
 
1742{
1743	struct kernel_siginfo info;
1744
1745	clear_siginfo(&info);
1746	info.si_signo = sig;
1747	info.si_errno = 0;
1748	info.si_code  = code;
1749	info.si_addr  = addr;
 
 
 
 
 
 
 
 
1750	return send_sig_info(info.si_signo, &info, t);
1751}
1752
1753int force_sig_mceerr(int code, void __user *addr, short lsb)
 
1754{
1755	struct kernel_siginfo info;
1756
1757	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1758	clear_siginfo(&info);
1759	info.si_signo = SIGBUS;
1760	info.si_errno = 0;
1761	info.si_code = code;
1762	info.si_addr = addr;
1763	info.si_addr_lsb = lsb;
1764	return force_sig_info(&info);
1765}
1766
1767int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
1768{
1769	struct kernel_siginfo info;
1770
1771	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
1772	clear_siginfo(&info);
1773	info.si_signo = SIGBUS;
1774	info.si_errno = 0;
1775	info.si_code = code;
1776	info.si_addr = addr;
1777	info.si_addr_lsb = lsb;
1778	return send_sig_info(info.si_signo, &info, t);
1779}
1780EXPORT_SYMBOL(send_sig_mceerr);
 
1781
 
1782int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
1783{
1784	struct kernel_siginfo info;
1785
1786	clear_siginfo(&info);
1787	info.si_signo = SIGSEGV;
1788	info.si_errno = 0;
1789	info.si_code  = SEGV_BNDERR;
1790	info.si_addr  = addr;
1791	info.si_lower = lower;
1792	info.si_upper = upper;
1793	return force_sig_info(&info);
1794}
 
1795
1796#ifdef SEGV_PKUERR
1797int force_sig_pkuerr(void __user *addr, u32 pkey)
1798{
1799	struct kernel_siginfo info;
1800
1801	clear_siginfo(&info);
1802	info.si_signo = SIGSEGV;
1803	info.si_errno = 0;
1804	info.si_code  = SEGV_PKUERR;
1805	info.si_addr  = addr;
1806	info.si_pkey  = pkey;
1807	return force_sig_info(&info);
1808}
1809#endif
1810
1811int send_sig_perf(void __user *addr, u32 type, u64 sig_data)
1812{
1813	struct kernel_siginfo info;
1814
1815	clear_siginfo(&info);
1816	info.si_signo     = SIGTRAP;
1817	info.si_errno     = 0;
1818	info.si_code      = TRAP_PERF;
1819	info.si_addr      = addr;
1820	info.si_perf_data = sig_data;
1821	info.si_perf_type = type;
1822
1823	/*
1824	 * Signals generated by perf events should not terminate the whole
1825	 * process if SIGTRAP is blocked, however, delivering the signal
1826	 * asynchronously is better than not delivering at all. But tell user
1827	 * space if the signal was asynchronous, so it can clearly be
1828	 * distinguished from normal synchronous ones.
1829	 */
1830	info.si_perf_flags = sigismember(&current->blocked, info.si_signo) ?
1831				     TRAP_PERF_FLAG_ASYNC :
1832				     0;
1833
1834	return send_sig_info(info.si_signo, &info, current);
1835}
1836
1837/**
1838 * force_sig_seccomp - signals the task to allow in-process syscall emulation
1839 * @syscall: syscall number to send to userland
1840 * @reason: filter-supplied reason code to send to userland (via si_errno)
1841 * @force_coredump: true to trigger a coredump
1842 *
1843 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
1844 */
1845int force_sig_seccomp(int syscall, int reason, bool force_coredump)
1846{
1847	struct kernel_siginfo info;
1848
1849	clear_siginfo(&info);
1850	info.si_signo = SIGSYS;
1851	info.si_code = SYS_SECCOMP;
1852	info.si_call_addr = (void __user *)KSTK_EIP(current);
1853	info.si_errno = reason;
1854	info.si_arch = syscall_get_arch(current);
1855	info.si_syscall = syscall;
1856	return force_sig_info_to_task(&info, current,
1857		force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
1858}
1859
1860/* For the crazy architectures that include trap information in
1861 * the errno field, instead of an actual errno value.
1862 */
1863int force_sig_ptrace_errno_trap(int errno, void __user *addr)
1864{
1865	struct kernel_siginfo info;
1866
1867	clear_siginfo(&info);
1868	info.si_signo = SIGTRAP;
1869	info.si_errno = errno;
1870	info.si_code  = TRAP_HWBKPT;
1871	info.si_addr  = addr;
1872	return force_sig_info(&info);
1873}
1874
1875/* For the rare architectures that include trap information using
1876 * si_trapno.
1877 */
1878int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
1879{
1880	struct kernel_siginfo info;
1881
1882	clear_siginfo(&info);
1883	info.si_signo = sig;
1884	info.si_errno = 0;
1885	info.si_code  = code;
1886	info.si_addr  = addr;
1887	info.si_trapno = trapno;
1888	return force_sig_info(&info);
1889}
1890
1891/* For the rare architectures that include trap information using
1892 * si_trapno.
1893 */
1894int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
1895			  struct task_struct *t)
1896{
1897	struct kernel_siginfo info;
1898
1899	clear_siginfo(&info);
1900	info.si_signo = sig;
1901	info.si_errno = 0;
1902	info.si_code  = code;
1903	info.si_addr  = addr;
1904	info.si_trapno = trapno;
1905	return send_sig_info(info.si_signo, &info, t);
1906}
1907
1908static int kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp)
1909{
1910	int ret;
1911	read_lock(&tasklist_lock);
1912	ret = __kill_pgrp_info(sig, info, pgrp);
1913	read_unlock(&tasklist_lock);
 
1914	return ret;
1915}
1916
1917int kill_pgrp(struct pid *pid, int sig, int priv)
1918{
1919	return kill_pgrp_info(sig, __si_special(priv), pid);
1920}
1921EXPORT_SYMBOL(kill_pgrp);
1922
1923int kill_pid(struct pid *pid, int sig, int priv)
1924{
1925	return kill_pid_info(sig, __si_special(priv), pid);
1926}
1927EXPORT_SYMBOL(kill_pid);
1928
1929/*
1930 * These functions support sending signals using preallocated sigqueue
1931 * structures.  This is needed "because realtime applications cannot
1932 * afford to lose notifications of asynchronous events, like timer
1933 * expirations or I/O completions".  In the case of POSIX Timers
1934 * we allocate the sigqueue structure from the timer_create.  If this
1935 * allocation fails we are able to report the failure to the application
1936 * with an EAGAIN error.
1937 */
1938struct sigqueue *sigqueue_alloc(void)
1939{
1940	return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);
 
 
 
 
 
1941}
1942
1943void sigqueue_free(struct sigqueue *q)
1944{
1945	unsigned long flags;
1946	spinlock_t *lock = &current->sighand->siglock;
1947
1948	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1949	/*
1950	 * We must hold ->siglock while testing q->list
1951	 * to serialize with collect_signal() or with
1952	 * __exit_signal()->flush_sigqueue().
1953	 */
1954	spin_lock_irqsave(lock, flags);
1955	q->flags &= ~SIGQUEUE_PREALLOC;
1956	/*
1957	 * If it is queued it will be freed when dequeued,
1958	 * like the "regular" sigqueue.
1959	 */
1960	if (!list_empty(&q->list))
1961		q = NULL;
1962	spin_unlock_irqrestore(lock, flags);
1963
1964	if (q)
1965		__sigqueue_free(q);
1966}
1967
1968int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
1969{
1970	int sig = q->info.si_signo;
1971	struct sigpending *pending;
1972	struct task_struct *t;
1973	unsigned long flags;
1974	int ret, result;
1975
1976	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1977
1978	ret = -1;
1979	rcu_read_lock();
1980
1981	/*
1982	 * This function is used by POSIX timers to deliver a timer signal.
1983	 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
1984	 * set), the signal must be delivered to the specific thread (queues
1985	 * into t->pending).
1986	 *
1987	 * Where type is not PIDTYPE_PID, signals must be delivered to the
1988	 * process. In this case, prefer to deliver to current if it is in
1989	 * the same thread group as the target process, which avoids
1990	 * unnecessarily waking up a potentially idle task.
1991	 */
1992	t = pid_task(pid, type);
1993	if (!t)
1994		goto ret;
1995	if (type != PIDTYPE_PID && same_thread_group(t, current))
1996		t = current;
1997	if (!likely(lock_task_sighand(t, &flags)))
1998		goto ret;
1999
2000	ret = 1; /* the signal is ignored */
2001	result = TRACE_SIGNAL_IGNORED;
2002	if (!prepare_signal(sig, t, false))
2003		goto out;
2004
2005	ret = 0;
2006	if (unlikely(!list_empty(&q->list))) {
2007		/*
2008		 * If an SI_TIMER entry is already queue just increment
2009		 * the overrun count.
2010		 */
2011		BUG_ON(q->info.si_code != SI_TIMER);
2012		q->info.si_overrun++;
2013		result = TRACE_SIGNAL_ALREADY_PENDING;
2014		goto out;
2015	}
2016	q->info.si_overrun = 0;
2017
2018	signalfd_notify(t, sig);
2019	pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
2020	list_add_tail(&q->list, &pending->list);
2021	sigaddset(&pending->signal, sig);
2022	complete_signal(sig, t, type);
2023	result = TRACE_SIGNAL_DELIVERED;
2024out:
2025	trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result);
2026	unlock_task_sighand(t, &flags);
2027ret:
2028	rcu_read_unlock();
2029	return ret;
2030}
2031
2032void do_notify_pidfd(struct task_struct *task)
2033{
2034	struct pid *pid = task_pid(task);
2035
2036	WARN_ON(task->exit_state == 0);
2037
2038	__wake_up(&pid->wait_pidfd, TASK_NORMAL, 0,
2039			poll_to_key(EPOLLIN | EPOLLRDNORM));
2040}
2041
2042/*
2043 * Let a parent know about the death of a child.
2044 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
2045 *
2046 * Returns true if our parent ignored us and so we've switched to
2047 * self-reaping.
2048 */
2049bool do_notify_parent(struct task_struct *tsk, int sig)
2050{
2051	struct kernel_siginfo info;
2052	unsigned long flags;
2053	struct sighand_struct *psig;
2054	bool autoreap = false;
2055	u64 utime, stime;
2056
2057	WARN_ON_ONCE(sig == -1);
2058
2059	/* do_notify_parent_cldstop should have been called instead.  */
2060	WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
2061
2062	WARN_ON_ONCE(!tsk->ptrace &&
2063	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
2064	/*
2065	 * tsk is a group leader and has no threads, wake up the
2066	 * non-PIDFD_THREAD waiters.
2067	 */
2068	if (thread_group_empty(tsk))
2069		do_notify_pidfd(tsk);
2070
2071	if (sig != SIGCHLD) {
2072		/*
2073		 * This is only possible if parent == real_parent.
2074		 * Check if it has changed security domain.
2075		 */
2076		if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
2077			sig = SIGCHLD;
2078	}
2079
2080	clear_siginfo(&info);
2081	info.si_signo = sig;
2082	info.si_errno = 0;
2083	/*
2084	 * We are under tasklist_lock here so our parent is tied to
2085	 * us and cannot change.
2086	 *
2087	 * task_active_pid_ns will always return the same pid namespace
2088	 * until a task passes through release_task.
2089	 *
2090	 * write_lock() currently calls preempt_disable() which is the
2091	 * same as rcu_read_lock(), but according to Oleg, this is not
2092	 * correct to rely on this
2093	 */
2094	rcu_read_lock();
2095	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
2096	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
2097				       task_uid(tsk));
2098	rcu_read_unlock();
2099
2100	task_cputime(tsk, &utime, &stime);
2101	info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
2102	info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
2103
2104	info.si_status = tsk->exit_code & 0x7f;
2105	if (tsk->exit_code & 0x80)
2106		info.si_code = CLD_DUMPED;
2107	else if (tsk->exit_code & 0x7f)
2108		info.si_code = CLD_KILLED;
2109	else {
2110		info.si_code = CLD_EXITED;
2111		info.si_status = tsk->exit_code >> 8;
2112	}
2113
2114	psig = tsk->parent->sighand;
2115	spin_lock_irqsave(&psig->siglock, flags);
2116	if (!tsk->ptrace && sig == SIGCHLD &&
2117	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
2118	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
2119		/*
2120		 * We are exiting and our parent doesn't care.  POSIX.1
2121		 * defines special semantics for setting SIGCHLD to SIG_IGN
2122		 * or setting the SA_NOCLDWAIT flag: we should be reaped
2123		 * automatically and not left for our parent's wait4 call.
2124		 * Rather than having the parent do it as a magic kind of
2125		 * signal handler, we just set this to tell do_exit that we
2126		 * can be cleaned up without becoming a zombie.  Note that
2127		 * we still call __wake_up_parent in this case, because a
2128		 * blocked sys_wait4 might now return -ECHILD.
2129		 *
2130		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
2131		 * is implementation-defined: we do (if you don't want
2132		 * it, just use SIG_IGN instead).
2133		 */
2134		autoreap = true;
2135		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
2136			sig = 0;
2137	}
2138	/*
2139	 * Send with __send_signal as si_pid and si_uid are in the
2140	 * parent's namespaces.
2141	 */
2142	if (valid_signal(sig) && sig)
2143		__send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false);
2144	__wake_up_parent(tsk, tsk->parent);
2145	spin_unlock_irqrestore(&psig->siglock, flags);
2146
2147	return autoreap;
2148}
2149
2150/**
2151 * do_notify_parent_cldstop - notify parent of stopped/continued state change
2152 * @tsk: task reporting the state change
2153 * @for_ptracer: the notification is for ptracer
2154 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
2155 *
2156 * Notify @tsk's parent that the stopped/continued state has changed.  If
2157 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
2158 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
2159 *
2160 * CONTEXT:
2161 * Must be called with tasklist_lock at least read locked.
2162 */
2163static void do_notify_parent_cldstop(struct task_struct *tsk,
2164				     bool for_ptracer, int why)
2165{
2166	struct kernel_siginfo info;
2167	unsigned long flags;
2168	struct task_struct *parent;
2169	struct sighand_struct *sighand;
2170	u64 utime, stime;
2171
2172	if (for_ptracer) {
2173		parent = tsk->parent;
2174	} else {
2175		tsk = tsk->group_leader;
2176		parent = tsk->real_parent;
2177	}
2178
2179	clear_siginfo(&info);
2180	info.si_signo = SIGCHLD;
2181	info.si_errno = 0;
2182	/*
2183	 * see comment in do_notify_parent() about the following 4 lines
2184	 */
2185	rcu_read_lock();
2186	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
2187	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
2188	rcu_read_unlock();
2189
2190	task_cputime(tsk, &utime, &stime);
2191	info.si_utime = nsec_to_clock_t(utime);
2192	info.si_stime = nsec_to_clock_t(stime);
2193
2194 	info.si_code = why;
2195 	switch (why) {
2196 	case CLD_CONTINUED:
2197 		info.si_status = SIGCONT;
2198 		break;
2199 	case CLD_STOPPED:
2200 		info.si_status = tsk->signal->group_exit_code & 0x7f;
2201 		break;
2202 	case CLD_TRAPPED:
2203 		info.si_status = tsk->exit_code & 0x7f;
2204 		break;
2205 	default:
2206 		BUG();
2207 	}
2208
2209	sighand = parent->sighand;
2210	spin_lock_irqsave(&sighand->siglock, flags);
2211	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
2212	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
2213		send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID);
2214	/*
2215	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
2216	 */
2217	__wake_up_parent(tsk, parent);
2218	spin_unlock_irqrestore(&sighand->siglock, flags);
2219}
2220
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2221/*
2222 * This must be called with current->sighand->siglock held.
2223 *
2224 * This should be the path for all ptrace stops.
2225 * We always set current->last_siginfo while stopped here.
2226 * That makes it a way to test a stopped process for
2227 * being ptrace-stopped vs being job-control-stopped.
2228 *
2229 * Returns the signal the ptracer requested the code resume
2230 * with.  If the code did not stop because the tracer is gone,
2231 * the stop signal remains unchanged unless clear_code.
2232 */
2233static int ptrace_stop(int exit_code, int why, unsigned long message,
2234		       kernel_siginfo_t *info)
2235	__releases(&current->sighand->siglock)
2236	__acquires(&current->sighand->siglock)
2237{
2238	bool gstop_done = false;
2239
2240	if (arch_ptrace_stop_needed()) {
2241		/*
2242		 * The arch code has something special to do before a
2243		 * ptrace stop.  This is allowed to block, e.g. for faults
2244		 * on user stack pages.  We can't keep the siglock while
2245		 * calling arch_ptrace_stop, so we must release it now.
2246		 * To preserve proper semantics, we must do this before
2247		 * any signal bookkeeping like checking group_stop_count.
 
 
 
2248		 */
2249		spin_unlock_irq(&current->sighand->siglock);
2250		arch_ptrace_stop();
2251		spin_lock_irq(&current->sighand->siglock);
 
 
2252	}
2253
2254	/*
2255	 * After this point ptrace_signal_wake_up or signal_wake_up
2256	 * will clear TASK_TRACED if ptrace_unlink happens or a fatal
2257	 * signal comes in.  Handle previous ptrace_unlinks and fatal
2258	 * signals here to prevent ptrace_stop sleeping in schedule.
2259	 */
2260	if (!current->ptrace || __fatal_signal_pending(current))
2261		return exit_code;
2262
2263	set_special_state(TASK_TRACED);
2264	current->jobctl |= JOBCTL_TRACED;
2265
2266	/*
2267	 * We're committing to trapping.  TRACED should be visible before
2268	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
2269	 * Also, transition to TRACED and updates to ->jobctl should be
2270	 * atomic with respect to siglock and should be done after the arch
2271	 * hook as siglock is released and regrabbed across it.
2272	 *
2273	 *     TRACER				    TRACEE
2274	 *
2275	 *     ptrace_attach()
2276	 * [L]   wait_on_bit(JOBCTL_TRAPPING)	[S] set_special_state(TRACED)
2277	 *     do_wait()
2278	 *       set_current_state()                smp_wmb();
2279	 *       ptrace_do_wait()
2280	 *         wait_task_stopped()
2281	 *           task_stopped_code()
2282	 * [L]         task_is_traced()		[S] task_clear_jobctl_trapping();
2283	 */
2284	smp_wmb();
2285
2286	current->ptrace_message = message;
2287	current->last_siginfo = info;
2288	current->exit_code = exit_code;
2289
2290	/*
2291	 * If @why is CLD_STOPPED, we're trapping to participate in a group
2292	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
2293	 * across siglock relocks since INTERRUPT was scheduled, PENDING
2294	 * could be clear now.  We act as if SIGCONT is received after
2295	 * TASK_TRACED is entered - ignore it.
2296	 */
2297	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
2298		gstop_done = task_participate_group_stop(current);
2299
2300	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
2301	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
2302	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
2303		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
2304
2305	/* entering a trap, clear TRAPPING */
2306	task_clear_jobctl_trapping(current);
2307
2308	spin_unlock_irq(&current->sighand->siglock);
2309	read_lock(&tasklist_lock);
2310	/*
2311	 * Notify parents of the stop.
2312	 *
2313	 * While ptraced, there are two parents - the ptracer and
2314	 * the real_parent of the group_leader.  The ptracer should
2315	 * know about every stop while the real parent is only
2316	 * interested in the completion of group stop.  The states
2317	 * for the two don't interact with each other.  Notify
2318	 * separately unless they're gonna be duplicates.
2319	 */
2320	if (current->ptrace)
2321		do_notify_parent_cldstop(current, true, why);
2322	if (gstop_done && (!current->ptrace || ptrace_reparented(current)))
2323		do_notify_parent_cldstop(current, false, why);
2324
2325	/*
2326	 * The previous do_notify_parent_cldstop() invocation woke ptracer.
2327	 * One a PREEMPTION kernel this can result in preemption requirement
2328	 * which will be fulfilled after read_unlock() and the ptracer will be
2329	 * put on the CPU.
2330	 * The ptracer is in wait_task_inactive(, __TASK_TRACED) waiting for
2331	 * this task wait in schedule(). If this task gets preempted then it
2332	 * remains enqueued on the runqueue. The ptracer will observe this and
2333	 * then sleep for a delay of one HZ tick. In the meantime this task
2334	 * gets scheduled, enters schedule() and will wait for the ptracer.
2335	 *
2336	 * This preemption point is not bad from a correctness point of
2337	 * view but extends the runtime by one HZ tick time due to the
2338	 * ptracer's sleep.  The preempt-disable section ensures that there
2339	 * will be no preemption between unlock and schedule() and so
2340	 * improving the performance since the ptracer will observe that
2341	 * the tracee is scheduled out once it gets on the CPU.
2342	 *
2343	 * On PREEMPT_RT locking tasklist_lock does not disable preemption.
2344	 * Therefore the task can be preempted after do_notify_parent_cldstop()
2345	 * before unlocking tasklist_lock so there is no benefit in doing this.
2346	 *
2347	 * In fact disabling preemption is harmful on PREEMPT_RT because
2348	 * the spinlock_t in cgroup_enter_frozen() must not be acquired
2349	 * with preemption disabled due to the 'sleeping' spinlock
2350	 * substitution of RT.
2351	 */
2352	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2353		preempt_disable();
2354	read_unlock(&tasklist_lock);
2355	cgroup_enter_frozen();
2356	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
2357		preempt_enable_no_resched();
2358	schedule();
2359	cgroup_leave_frozen(true);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2360
2361	/*
2362	 * We are back.  Now reacquire the siglock before touching
2363	 * last_siginfo, so that we are sure to have synchronized with
2364	 * any signal-sending on another CPU that wants to examine it.
2365	 */
2366	spin_lock_irq(&current->sighand->siglock);
2367	exit_code = current->exit_code;
2368	current->last_siginfo = NULL;
2369	current->ptrace_message = 0;
2370	current->exit_code = 0;
2371
2372	/* LISTENING can be set only during STOP traps, clear it */
2373	current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN);
2374
2375	/*
2376	 * Queued signals ignored us while we were stopped for tracing.
2377	 * So check for any that we should take before resuming user mode.
2378	 * This sets TIF_SIGPENDING, but never clears it.
2379	 */
2380	recalc_sigpending_tsk(current);
2381	return exit_code;
2382}
2383
2384static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
2385{
2386	kernel_siginfo_t info;
2387
2388	clear_siginfo(&info);
2389	info.si_signo = signr;
2390	info.si_code = exit_code;
2391	info.si_pid = task_pid_vnr(current);
2392	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
2393
2394	/* Let the debugger run.  */
2395	return ptrace_stop(exit_code, why, message, &info);
2396}
2397
2398int ptrace_notify(int exit_code, unsigned long message)
2399{
2400	int signr;
2401
2402	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2403	if (unlikely(task_work_pending(current)))
2404		task_work_run();
2405
2406	spin_lock_irq(&current->sighand->siglock);
2407	signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
2408	spin_unlock_irq(&current->sighand->siglock);
2409	return signr;
2410}
2411
2412/**
2413 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
2414 * @signr: signr causing group stop if initiating
2415 *
2416 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
2417 * and participate in it.  If already set, participate in the existing
2418 * group stop.  If participated in a group stop (and thus slept), %true is
2419 * returned with siglock released.
2420 *
2421 * If ptraced, this function doesn't handle stop itself.  Instead,
2422 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
2423 * untouched.  The caller must ensure that INTERRUPT trap handling takes
2424 * places afterwards.
2425 *
2426 * CONTEXT:
2427 * Must be called with @current->sighand->siglock held, which is released
2428 * on %true return.
2429 *
2430 * RETURNS:
2431 * %false if group stop is already cancelled or ptrace trap is scheduled.
2432 * %true if participated in group stop.
2433 */
2434static bool do_signal_stop(int signr)
2435	__releases(&current->sighand->siglock)
2436{
2437	struct signal_struct *sig = current->signal;
2438
2439	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2440		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2441		struct task_struct *t;
2442
2443		/* signr will be recorded in task->jobctl for retries */
2444		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2445
2446		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2447		    unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
2448		    unlikely(sig->group_exec_task))
2449			return false;
2450		/*
2451		 * There is no group stop already in progress.  We must
2452		 * initiate one now.
2453		 *
2454		 * While ptraced, a task may be resumed while group stop is
2455		 * still in effect and then receive a stop signal and
2456		 * initiate another group stop.  This deviates from the
2457		 * usual behavior as two consecutive stop signals can't
2458		 * cause two group stops when !ptraced.  That is why we
2459		 * also check !task_is_stopped(t) below.
2460		 *
2461		 * The condition can be distinguished by testing whether
2462		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
2463		 * group_exit_code in such case.
2464		 *
2465		 * This is not necessary for SIGNAL_STOP_CONTINUED because
2466		 * an intervening stop signal is required to cause two
2467		 * continued events regardless of ptrace.
2468		 */
2469		if (!(sig->flags & SIGNAL_STOP_STOPPED))
2470			sig->group_exit_code = signr;
2471
2472		sig->group_stop_count = 0;
 
2473		if (task_set_jobctl_pending(current, signr | gstop))
2474			sig->group_stop_count++;
2475
2476		for_other_threads(current, t) {
 
2477			/*
2478			 * Setting state to TASK_STOPPED for a group
2479			 * stop is always done with the siglock held,
2480			 * so this check has no races.
2481			 */
2482			if (!task_is_stopped(t) &&
2483			    task_set_jobctl_pending(t, signr | gstop)) {
2484				sig->group_stop_count++;
2485				if (likely(!(t->ptrace & PT_SEIZED)))
2486					signal_wake_up(t, 0);
2487				else
2488					ptrace_trap_notify(t);
2489			}
2490		}
2491	}
2492
2493	if (likely(!current->ptrace)) {
2494		int notify = 0;
2495
2496		/*
2497		 * If there are no other threads in the group, or if there
2498		 * is a group stop in progress and we are the last to stop,
2499		 * report to the parent.
2500		 */
2501		if (task_participate_group_stop(current))
2502			notify = CLD_STOPPED;
2503
2504		current->jobctl |= JOBCTL_STOPPED;
2505		set_special_state(TASK_STOPPED);
2506		spin_unlock_irq(&current->sighand->siglock);
2507
2508		/*
2509		 * Notify the parent of the group stop completion.  Because
2510		 * we're not holding either the siglock or tasklist_lock
2511		 * here, ptracer may attach inbetween; however, this is for
2512		 * group stop and should always be delivered to the real
2513		 * parent of the group leader.  The new ptracer will get
2514		 * its notification when this task transitions into
2515		 * TASK_TRACED.
2516		 */
2517		if (notify) {
2518			read_lock(&tasklist_lock);
2519			do_notify_parent_cldstop(current, false, notify);
2520			read_unlock(&tasklist_lock);
2521		}
2522
2523		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2524		cgroup_enter_frozen();
2525		schedule();
2526		return true;
2527	} else {
2528		/*
2529		 * While ptraced, group stop is handled by STOP trap.
2530		 * Schedule it and let the caller deal with it.
2531		 */
2532		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
2533		return false;
2534	}
2535}
2536
2537/**
2538 * do_jobctl_trap - take care of ptrace jobctl traps
2539 *
2540 * When PT_SEIZED, it's used for both group stop and explicit
2541 * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
2542 * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
2543 * the stop signal; otherwise, %SIGTRAP.
2544 *
2545 * When !PT_SEIZED, it's used only for group stop trap with stop signal
2546 * number as exit_code and no siginfo.
2547 *
2548 * CONTEXT:
2549 * Must be called with @current->sighand->siglock held, which may be
2550 * released and re-acquired before returning with intervening sleep.
2551 */
2552static void do_jobctl_trap(void)
2553{
2554	struct signal_struct *signal = current->signal;
2555	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2556
2557	if (current->ptrace & PT_SEIZED) {
2558		if (!signal->group_stop_count &&
2559		    !(signal->flags & SIGNAL_STOP_STOPPED))
2560			signr = SIGTRAP;
2561		WARN_ON_ONCE(!signr);
2562		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
2563				 CLD_STOPPED, 0);
2564	} else {
2565		WARN_ON_ONCE(!signr);
2566		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
 
2567	}
2568}
2569
2570/**
2571 * do_freezer_trap - handle the freezer jobctl trap
2572 *
2573 * Puts the task into frozen state, if only the task is not about to quit.
2574 * In this case it drops JOBCTL_TRAP_FREEZE.
2575 *
2576 * CONTEXT:
2577 * Must be called with @current->sighand->siglock held,
2578 * which is always released before returning.
2579 */
2580static void do_freezer_trap(void)
2581	__releases(&current->sighand->siglock)
2582{
2583	/*
2584	 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
2585	 * let's make another loop to give it a chance to be handled.
2586	 * In any case, we'll return back.
2587	 */
2588	if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
2589	     JOBCTL_TRAP_FREEZE) {
2590		spin_unlock_irq(&current->sighand->siglock);
2591		return;
2592	}
2593
2594	/*
2595	 * Now we're sure that there is no pending fatal signal and no
2596	 * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
2597	 * immediately (if there is a non-fatal signal pending), and
2598	 * put the task into sleep.
2599	 */
2600	__set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2601	clear_thread_flag(TIF_SIGPENDING);
2602	spin_unlock_irq(&current->sighand->siglock);
2603	cgroup_enter_frozen();
2604	schedule();
2605}
2606
2607static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
2608{
2609	/*
2610	 * We do not check sig_kernel_stop(signr) but set this marker
2611	 * unconditionally because we do not know whether debugger will
2612	 * change signr. This flag has no meaning unless we are going
2613	 * to stop after return from ptrace_stop(). In this case it will
2614	 * be checked in do_signal_stop(), we should only stop if it was
2615	 * not cleared by SIGCONT while we were sleeping. See also the
2616	 * comment in dequeue_signal().
2617	 */
2618	current->jobctl |= JOBCTL_STOP_DEQUEUED;
2619	signr = ptrace_stop(signr, CLD_TRAPPED, 0, info);
2620
2621	/* We're back.  Did the debugger cancel the sig?  */
 
2622	if (signr == 0)
2623		return signr;
2624
 
 
2625	/*
2626	 * Update the siginfo structure if the signal has
2627	 * changed.  If the debugger wanted something
2628	 * specific in the siginfo structure then it should
2629	 * have updated *info via PTRACE_SETSIGINFO.
2630	 */
2631	if (signr != info->si_signo) {
2632		clear_siginfo(info);
2633		info->si_signo = signr;
2634		info->si_errno = 0;
2635		info->si_code = SI_USER;
2636		rcu_read_lock();
2637		info->si_pid = task_pid_vnr(current->parent);
2638		info->si_uid = from_kuid_munged(current_user_ns(),
2639						task_uid(current->parent));
2640		rcu_read_unlock();
2641	}
2642
2643	/* If the (new) signal is now blocked, requeue it.  */
2644	if (sigismember(&current->blocked, signr) ||
2645	    fatal_signal_pending(current)) {
2646		send_signal_locked(signr, info, current, type);
2647		signr = 0;
2648	}
2649
2650	return signr;
2651}
2652
2653static void hide_si_addr_tag_bits(struct ksignal *ksig)
2654{
2655	switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
2656	case SIL_FAULT:
2657	case SIL_FAULT_TRAPNO:
2658	case SIL_FAULT_MCEERR:
2659	case SIL_FAULT_BNDERR:
2660	case SIL_FAULT_PKUERR:
2661	case SIL_FAULT_PERF_EVENT:
2662		ksig->info.si_addr = arch_untagged_si_addr(
2663			ksig->info.si_addr, ksig->sig, ksig->info.si_code);
2664		break;
2665	case SIL_KILL:
2666	case SIL_TIMER:
2667	case SIL_POLL:
2668	case SIL_CHLD:
2669	case SIL_RT:
2670	case SIL_SYS:
2671		break;
2672	}
2673}
2674
2675bool get_signal(struct ksignal *ksig)
2676{
2677	struct sighand_struct *sighand = current->sighand;
2678	struct signal_struct *signal = current->signal;
2679	int signr;
2680
2681	clear_notify_signal();
2682	if (unlikely(task_work_pending(current)))
2683		task_work_run();
2684
2685	if (!task_sigpending(current))
2686		return false;
2687
2688	if (unlikely(uprobe_deny_signal()))
2689		return false;
2690
2691	/*
2692	 * Do this once, we can't return to user-mode if freezing() == T.
2693	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
2694	 * thus do not need another check after return.
2695	 */
2696	try_to_freeze();
2697
2698relock:
2699	spin_lock_irq(&sighand->siglock);
2700
2701	/*
2702	 * Every stopped thread goes here after wakeup. Check to see if
2703	 * we should notify the parent, prepare_signal(SIGCONT) encodes
2704	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
2705	 */
2706	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2707		int why;
2708
2709		if (signal->flags & SIGNAL_CLD_CONTINUED)
2710			why = CLD_CONTINUED;
2711		else
2712			why = CLD_STOPPED;
2713
2714		signal->flags &= ~SIGNAL_CLD_MASK;
2715
2716		spin_unlock_irq(&sighand->siglock);
2717
2718		/*
2719		 * Notify the parent that we're continuing.  This event is
2720		 * always per-process and doesn't make whole lot of sense
2721		 * for ptracers, who shouldn't consume the state via
2722		 * wait(2) either, but, for backward compatibility, notify
2723		 * the ptracer of the group leader too unless it's gonna be
2724		 * a duplicate.
2725		 */
2726		read_lock(&tasklist_lock);
2727		do_notify_parent_cldstop(current, false, why);
2728
2729		if (ptrace_reparented(current->group_leader))
2730			do_notify_parent_cldstop(current->group_leader,
2731						true, why);
2732		read_unlock(&tasklist_lock);
2733
2734		goto relock;
2735	}
2736
2737	for (;;) {
2738		struct k_sigaction *ka;
2739		enum pid_type type;
2740
2741		/* Has this task already been marked for death? */
2742		if ((signal->flags & SIGNAL_GROUP_EXIT) ||
2743		     signal->group_exec_task) {
2744			signr = SIGKILL;
2745			sigdelset(&current->pending.signal, SIGKILL);
2746			trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
2747					     &sighand->action[SIGKILL-1]);
2748			recalc_sigpending();
2749			/*
2750			 * implies do_group_exit() or return to PF_USER_WORKER,
2751			 * no need to initialize ksig->info/etc.
2752			 */
2753			goto fatal;
2754		}
2755
2756		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
2757		    do_signal_stop(0))
2758			goto relock;
2759
2760		if (unlikely(current->jobctl &
2761			     (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
2762			if (current->jobctl & JOBCTL_TRAP_MASK) {
2763				do_jobctl_trap();
2764				spin_unlock_irq(&sighand->siglock);
2765			} else if (current->jobctl & JOBCTL_TRAP_FREEZE)
2766				do_freezer_trap();
2767
2768			goto relock;
2769		}
2770
2771		/*
2772		 * If the task is leaving the frozen state, let's update
2773		 * cgroup counters and reset the frozen bit.
2774		 */
2775		if (unlikely(cgroup_task_frozen(current))) {
2776			spin_unlock_irq(&sighand->siglock);
2777			cgroup_leave_frozen(false);
2778			goto relock;
2779		}
2780
2781		/*
2782		 * Signals generated by the execution of an instruction
2783		 * need to be delivered before any other pending signals
2784		 * so that the instruction pointer in the signal stack
2785		 * frame points to the faulting instruction.
2786		 */
2787		type = PIDTYPE_PID;
2788		signr = dequeue_synchronous_signal(&ksig->info);
2789		if (!signr)
2790			signr = dequeue_signal(current, &current->blocked,
2791					       &ksig->info, &type);
2792
2793		if (!signr)
2794			break; /* will return 0 */
2795
2796		if (unlikely(current->ptrace) && (signr != SIGKILL) &&
2797		    !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
2798			signr = ptrace_signal(signr, &ksig->info, type);
2799			if (!signr)
2800				continue;
2801		}
2802
2803		ka = &sighand->action[signr-1];
2804
2805		/* Trace actually delivered signals. */
2806		trace_signal_deliver(signr, &ksig->info, ka);
2807
2808		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
2809			continue;
2810		if (ka->sa.sa_handler != SIG_DFL) {
2811			/* Run the handler.  */
2812			ksig->ka = *ka;
2813
2814			if (ka->sa.sa_flags & SA_ONESHOT)
2815				ka->sa.sa_handler = SIG_DFL;
2816
2817			break; /* will return non-zero "signr" value */
2818		}
2819
2820		/*
2821		 * Now we are doing the default action for this signal.
2822		 */
2823		if (sig_kernel_ignore(signr)) /* Default is nothing. */
2824			continue;
2825
2826		/*
2827		 * Global init gets no signals it doesn't want.
2828		 * Container-init gets no signals it doesn't want from same
2829		 * container.
2830		 *
2831		 * Note that if global/container-init sees a sig_kernel_only()
2832		 * signal here, the signal must have been generated internally
2833		 * or must have come from an ancestor namespace. In either
2834		 * case, the signal cannot be dropped.
2835		 */
2836		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2837				!sig_kernel_only(signr))
2838			continue;
2839
2840		if (sig_kernel_stop(signr)) {
2841			/*
2842			 * The default action is to stop all threads in
2843			 * the thread group.  The job control signals
2844			 * do nothing in an orphaned pgrp, but SIGSTOP
2845			 * always works.  Note that siglock needs to be
2846			 * dropped during the call to is_orphaned_pgrp()
2847			 * because of lock ordering with tasklist_lock.
2848			 * This allows an intervening SIGCONT to be posted.
2849			 * We need to check for that and bail out if necessary.
2850			 */
2851			if (signr != SIGSTOP) {
2852				spin_unlock_irq(&sighand->siglock);
2853
2854				/* signals can be posted during this window */
2855
2856				if (is_current_pgrp_orphaned())
2857					goto relock;
2858
2859				spin_lock_irq(&sighand->siglock);
2860			}
2861
2862			if (likely(do_signal_stop(signr))) {
2863				/* It released the siglock.  */
2864				goto relock;
2865			}
2866
2867			/*
2868			 * We didn't actually stop, due to a race
2869			 * with SIGCONT or something like that.
2870			 */
2871			continue;
2872		}
2873
2874	fatal:
2875		spin_unlock_irq(&sighand->siglock);
2876		if (unlikely(cgroup_task_frozen(current)))
2877			cgroup_leave_frozen(true);
2878
2879		/*
2880		 * Anything else is fatal, maybe with a core dump.
2881		 */
2882		current->flags |= PF_SIGNALED;
2883
2884		if (sig_kernel_coredump(signr)) {
2885			if (print_fatal_signals)
2886				print_fatal_signal(signr);
2887			proc_coredump_connector(current);
2888			/*
2889			 * If it was able to dump core, this kills all
2890			 * other threads in the group and synchronizes with
2891			 * their demise.  If we lost the race with another
2892			 * thread getting here, it set group_exit_code
2893			 * first and our do_group_exit call below will use
2894			 * that value and ignore the one we pass it.
2895			 */
2896			do_coredump(&ksig->info);
2897		}
2898
2899		/*
2900		 * PF_USER_WORKER threads will catch and exit on fatal signals
2901		 * themselves. They have cleanup that must be performed, so we
2902		 * cannot call do_exit() on their behalf. Note that ksig won't
2903		 * be properly initialized, PF_USER_WORKER's shouldn't use it.
2904		 */
2905		if (current->flags & PF_USER_WORKER)
2906			goto out;
2907
2908		/*
2909		 * Death signals, no core dump.
2910		 */
2911		do_group_exit(signr);
2912		/* NOTREACHED */
2913	}
2914	spin_unlock_irq(&sighand->siglock);
2915
2916	ksig->sig = signr;
2917
2918	if (signr && !(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS))
2919		hide_si_addr_tag_bits(ksig);
2920out:
2921	return signr > 0;
2922}
2923
2924/**
2925 * signal_delivered - called after signal delivery to update blocked signals
2926 * @ksig:		kernel signal struct
2927 * @stepping:		nonzero if debugger single-step or block-step in use
2928 *
2929 * This function should be called when a signal has successfully been
2930 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
2931 * is always blocked), and the signal itself is blocked unless %SA_NODEFER
2932 * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2933 */
2934static void signal_delivered(struct ksignal *ksig, int stepping)
2935{
2936	sigset_t blocked;
2937
2938	/* A signal was successfully delivered, and the
2939	   saved sigmask was stored on the signal frame,
2940	   and will be restored by sigreturn.  So we can
2941	   simply clear the restore sigmask flag.  */
2942	clear_restore_sigmask();
2943
2944	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
2945	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
2946		sigaddset(&blocked, ksig->sig);
2947	set_current_blocked(&blocked);
2948	if (current->sas_ss_flags & SS_AUTODISARM)
2949		sas_ss_reset(current);
2950	if (stepping)
2951		ptrace_notify(SIGTRAP, 0);
2952}
2953
2954void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
2955{
2956	if (failed)
2957		force_sigsegv(ksig->sig);
2958	else
2959		signal_delivered(ksig, stepping);
2960}
2961
2962/*
2963 * It could be that complete_signal() picked us to notify about the
2964 * group-wide signal. Other threads should be notified now to take
2965 * the shared signals in @which since we will not.
2966 */
2967static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2968{
2969	sigset_t retarget;
2970	struct task_struct *t;
2971
2972	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
2973	if (sigisemptyset(&retarget))
2974		return;
2975
2976	for_other_threads(tsk, t) {
 
2977		if (t->flags & PF_EXITING)
2978			continue;
2979
2980		if (!has_pending_signals(&retarget, &t->blocked))
2981			continue;
2982		/* Remove the signals this thread can handle. */
2983		sigandsets(&retarget, &retarget, &t->blocked);
2984
2985		if (!task_sigpending(t))
2986			signal_wake_up(t, 0);
2987
2988		if (sigisemptyset(&retarget))
2989			break;
2990	}
2991}
2992
2993void exit_signals(struct task_struct *tsk)
2994{
2995	int group_stop = 0;
2996	sigset_t unblocked;
2997
2998	/*
2999	 * @tsk is about to have PF_EXITING set - lock out users which
3000	 * expect stable threadgroup.
3001	 */
3002	cgroup_threadgroup_change_begin(tsk);
3003
3004	if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
3005		sched_mm_cid_exit_signals(tsk);
3006		tsk->flags |= PF_EXITING;
3007		cgroup_threadgroup_change_end(tsk);
3008		return;
3009	}
3010
3011	spin_lock_irq(&tsk->sighand->siglock);
3012	/*
3013	 * From now this task is not visible for group-wide signals,
3014	 * see wants_signal(), do_signal_stop().
3015	 */
3016	sched_mm_cid_exit_signals(tsk);
3017	tsk->flags |= PF_EXITING;
3018
3019	cgroup_threadgroup_change_end(tsk);
3020
3021	if (!task_sigpending(tsk))
3022		goto out;
3023
3024	unblocked = tsk->blocked;
3025	signotset(&unblocked);
3026	retarget_shared_pending(tsk, &unblocked);
3027
3028	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
3029	    task_participate_group_stop(tsk))
3030		group_stop = CLD_STOPPED;
3031out:
3032	spin_unlock_irq(&tsk->sighand->siglock);
3033
3034	/*
3035	 * If group stop has completed, deliver the notification.  This
3036	 * should always go to the real parent of the group leader.
3037	 */
3038	if (unlikely(group_stop)) {
3039		read_lock(&tasklist_lock);
3040		do_notify_parent_cldstop(tsk, false, group_stop);
3041		read_unlock(&tasklist_lock);
3042	}
3043}
3044
 
 
 
 
 
 
 
 
3045/*
3046 * System call entry points.
3047 */
3048
3049/**
3050 *  sys_restart_syscall - restart a system call
3051 */
3052SYSCALL_DEFINE0(restart_syscall)
3053{
3054	struct restart_block *restart = &current->restart_block;
3055	return restart->fn(restart);
3056}
3057
3058long do_no_restart_syscall(struct restart_block *param)
3059{
3060	return -EINTR;
3061}
3062
3063static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
3064{
3065	if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
3066		sigset_t newblocked;
3067		/* A set of now blocked but previously unblocked signals. */
3068		sigandnsets(&newblocked, newset, &current->blocked);
3069		retarget_shared_pending(tsk, &newblocked);
3070	}
3071	tsk->blocked = *newset;
3072	recalc_sigpending();
3073}
3074
3075/**
3076 * set_current_blocked - change current->blocked mask
3077 * @newset: new mask
3078 *
3079 * It is wrong to change ->blocked directly, this helper should be used
3080 * to ensure the process can't miss a shared signal we are going to block.
3081 */
3082void set_current_blocked(sigset_t *newset)
3083{
3084	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
3085	__set_current_blocked(newset);
3086}
3087
3088void __set_current_blocked(const sigset_t *newset)
3089{
3090	struct task_struct *tsk = current;
3091
3092	/*
3093	 * In case the signal mask hasn't changed, there is nothing we need
3094	 * to do. The current->blocked shouldn't be modified by other task.
3095	 */
3096	if (sigequalsets(&tsk->blocked, newset))
3097		return;
3098
3099	spin_lock_irq(&tsk->sighand->siglock);
3100	__set_task_blocked(tsk, newset);
3101	spin_unlock_irq(&tsk->sighand->siglock);
3102}
3103
3104/*
3105 * This is also useful for kernel threads that want to temporarily
3106 * (or permanently) block certain signals.
3107 *
3108 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
3109 * interface happily blocks "unblockable" signals like SIGKILL
3110 * and friends.
3111 */
3112int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
3113{
3114	struct task_struct *tsk = current;
3115	sigset_t newset;
3116
3117	/* Lockless, only current can change ->blocked, never from irq */
3118	if (oldset)
3119		*oldset = tsk->blocked;
3120
3121	switch (how) {
3122	case SIG_BLOCK:
3123		sigorsets(&newset, &tsk->blocked, set);
3124		break;
3125	case SIG_UNBLOCK:
3126		sigandnsets(&newset, &tsk->blocked, set);
3127		break;
3128	case SIG_SETMASK:
3129		newset = *set;
3130		break;
3131	default:
3132		return -EINVAL;
3133	}
3134
3135	__set_current_blocked(&newset);
3136	return 0;
3137}
3138EXPORT_SYMBOL(sigprocmask);
3139
3140/*
3141 * The api helps set app-provided sigmasks.
3142 *
3143 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
3144 * epoll_pwait where a new sigmask is passed from userland for the syscalls.
3145 *
3146 * Note that it does set_restore_sigmask() in advance, so it must be always
3147 * paired with restore_saved_sigmask_unless() before return from syscall.
3148 */
3149int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
3150{
3151	sigset_t kmask;
3152
3153	if (!umask)
3154		return 0;
3155	if (sigsetsize != sizeof(sigset_t))
3156		return -EINVAL;
3157	if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
3158		return -EFAULT;
3159
3160	set_restore_sigmask();
3161	current->saved_sigmask = current->blocked;
3162	set_current_blocked(&kmask);
3163
3164	return 0;
3165}
3166
3167#ifdef CONFIG_COMPAT
3168int set_compat_user_sigmask(const compat_sigset_t __user *umask,
3169			    size_t sigsetsize)
3170{
3171	sigset_t kmask;
3172
3173	if (!umask)
3174		return 0;
3175	if (sigsetsize != sizeof(compat_sigset_t))
3176		return -EINVAL;
3177	if (get_compat_sigset(&kmask, umask))
3178		return -EFAULT;
3179
3180	set_restore_sigmask();
3181	current->saved_sigmask = current->blocked;
3182	set_current_blocked(&kmask);
3183
3184	return 0;
3185}
3186#endif
3187
3188/**
3189 *  sys_rt_sigprocmask - change the list of currently blocked signals
3190 *  @how: whether to add, remove, or set signals
3191 *  @nset: stores pending signals
3192 *  @oset: previous value of signal mask if non-null
3193 *  @sigsetsize: size of sigset_t type
3194 */
3195SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
3196		sigset_t __user *, oset, size_t, sigsetsize)
3197{
3198	sigset_t old_set, new_set;
3199	int error;
3200
3201	/* XXX: Don't preclude handling different sized sigset_t's.  */
3202	if (sigsetsize != sizeof(sigset_t))
3203		return -EINVAL;
3204
3205	old_set = current->blocked;
3206
3207	if (nset) {
3208		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
3209			return -EFAULT;
3210		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3211
3212		error = sigprocmask(how, &new_set, NULL);
3213		if (error)
3214			return error;
3215	}
3216
3217	if (oset) {
3218		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
3219			return -EFAULT;
3220	}
3221
3222	return 0;
3223}
3224
3225#ifdef CONFIG_COMPAT
3226COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
3227		compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
3228{
3229	sigset_t old_set = current->blocked;
3230
3231	/* XXX: Don't preclude handling different sized sigset_t's.  */
3232	if (sigsetsize != sizeof(sigset_t))
3233		return -EINVAL;
3234
3235	if (nset) {
3236		sigset_t new_set;
3237		int error;
3238		if (get_compat_sigset(&new_set, nset))
3239			return -EFAULT;
3240		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
3241
3242		error = sigprocmask(how, &new_set, NULL);
3243		if (error)
3244			return error;
3245	}
3246	return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
3247}
3248#endif
3249
3250static void do_sigpending(sigset_t *set)
3251{
3252	spin_lock_irq(&current->sighand->siglock);
3253	sigorsets(set, &current->pending.signal,
3254		  &current->signal->shared_pending.signal);
3255	spin_unlock_irq(&current->sighand->siglock);
3256
3257	/* Outside the lock because only this thread touches it.  */
3258	sigandsets(set, &current->blocked, set);
 
3259}
3260
3261/**
3262 *  sys_rt_sigpending - examine a pending signal that has been raised
3263 *			while blocked
3264 *  @uset: stores pending signals
3265 *  @sigsetsize: size of sigset_t type or larger
3266 */
3267SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
3268{
3269	sigset_t set;
 
3270
3271	if (sigsetsize > sizeof(*uset))
3272		return -EINVAL;
3273
3274	do_sigpending(&set);
3275
3276	if (copy_to_user(uset, &set, sigsetsize))
3277		return -EFAULT;
3278
3279	return 0;
3280}
3281
3282#ifdef CONFIG_COMPAT
3283COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
3284		compat_size_t, sigsetsize)
3285{
3286	sigset_t set;
 
3287
3288	if (sigsetsize > sizeof(*uset))
3289		return -EINVAL;
3290
3291	do_sigpending(&set);
3292
3293	return put_compat_sigset(uset, &set, sigsetsize);
 
3294}
3295#endif
3296
3297static const struct {
3298	unsigned char limit, layout;
3299} sig_sicodes[] = {
3300	[SIGILL]  = { NSIGILL,  SIL_FAULT },
3301	[SIGFPE]  = { NSIGFPE,  SIL_FAULT },
3302	[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
3303	[SIGBUS]  = { NSIGBUS,  SIL_FAULT },
3304	[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
3305#if defined(SIGEMT)
3306	[SIGEMT]  = { NSIGEMT,  SIL_FAULT },
3307#endif
3308	[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
3309	[SIGPOLL] = { NSIGPOLL, SIL_POLL },
3310	[SIGSYS]  = { NSIGSYS,  SIL_SYS },
3311};
3312
3313static bool known_siginfo_layout(unsigned sig, int si_code)
3314{
3315	if (si_code == SI_KERNEL)
3316		return true;
3317	else if ((si_code > SI_USER)) {
3318		if (sig_specific_sicodes(sig)) {
3319			if (si_code <= sig_sicodes[sig].limit)
3320				return true;
3321		}
3322		else if (si_code <= NSIGPOLL)
3323			return true;
3324	}
3325	else if (si_code >= SI_DETHREAD)
3326		return true;
3327	else if (si_code == SI_ASYNCNL)
3328		return true;
3329	return false;
3330}
3331
3332enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
3333{
3334	enum siginfo_layout layout = SIL_KILL;
3335	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
3336		if ((sig < ARRAY_SIZE(sig_sicodes)) &&
3337		    (si_code <= sig_sicodes[sig].limit)) {
3338			layout = sig_sicodes[sig].layout;
3339			/* Handle the exceptions */
3340			if ((sig == SIGBUS) &&
3341			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
3342				layout = SIL_FAULT_MCEERR;
3343			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
3344				layout = SIL_FAULT_BNDERR;
3345#ifdef SEGV_PKUERR
3346			else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
3347				layout = SIL_FAULT_PKUERR;
3348#endif
3349			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
3350				layout = SIL_FAULT_PERF_EVENT;
3351			else if (IS_ENABLED(CONFIG_SPARC) &&
3352				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
3353				layout = SIL_FAULT_TRAPNO;
3354			else if (IS_ENABLED(CONFIG_ALPHA) &&
3355				 ((sig == SIGFPE) ||
3356				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
3357				layout = SIL_FAULT_TRAPNO;
3358		}
3359		else if (si_code <= NSIGPOLL)
3360			layout = SIL_POLL;
3361	} else {
3362		if (si_code == SI_TIMER)
3363			layout = SIL_TIMER;
3364		else if (si_code == SI_SIGIO)
3365			layout = SIL_POLL;
3366		else if (si_code < 0)
3367			layout = SIL_RT;
 
 
 
 
 
 
 
 
 
3368	}
3369	return layout;
3370}
3371
3372static inline char __user *si_expansion(const siginfo_t __user *info)
3373{
3374	return ((char __user *)info) + sizeof(struct kernel_siginfo);
3375}
3376
3377int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
3378{
3379	char __user *expansion = si_expansion(to);
3380	if (copy_to_user(to, from , sizeof(struct kernel_siginfo)))
3381		return -EFAULT;
3382	if (clear_user(expansion, SI_EXPANSION_SIZE))
3383		return -EFAULT;
3384	return 0;
3385}
3386
3387static int post_copy_siginfo_from_user(kernel_siginfo_t *info,
3388				       const siginfo_t __user *from)
3389{
3390	if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) {
3391		char __user *expansion = si_expansion(from);
3392		char buf[SI_EXPANSION_SIZE];
3393		int i;
3394		/*
3395		 * An unknown si_code might need more than
3396		 * sizeof(struct kernel_siginfo) bytes.  Verify all of the
3397		 * extra bytes are 0.  This guarantees copy_siginfo_to_user
3398		 * will return this data to userspace exactly.
3399		 */
3400		if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE))
3401			return -EFAULT;
3402		for (i = 0; i < SI_EXPANSION_SIZE; i++) {
3403			if (buf[i] != 0)
3404				return -E2BIG;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3405		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3406	}
3407	return 0;
3408}
3409
3410static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to,
3411				    const siginfo_t __user *from)
 
 
3412{
3413	if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3414		return -EFAULT;
3415	to->si_signo = signo;
3416	return post_copy_siginfo_from_user(to, from);
3417}
3418
3419int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from)
 
3420{
3421	if (copy_from_user(to, from, sizeof(struct kernel_siginfo)))
3422		return -EFAULT;
3423	return post_copy_siginfo_from_user(to, from);
3424}
3425
3426#ifdef CONFIG_COMPAT
3427/**
3428 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo
3429 * @to: compat siginfo destination
3430 * @from: kernel siginfo source
3431 *
3432 * Note: This function does not work properly for the SIGCHLD on x32, but
3433 * fortunately it doesn't have to.  The only valid callers for this function are
3434 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code.
3435 * The latter does not care because SIGCHLD will never cause a coredump.
3436 */
3437void copy_siginfo_to_external32(struct compat_siginfo *to,
3438		const struct kernel_siginfo *from)
3439{
3440	memset(to, 0, sizeof(*to));
3441
3442	to->si_signo = from->si_signo;
3443	to->si_errno = from->si_errno;
3444	to->si_code  = from->si_code;
3445	switch(siginfo_layout(from->si_signo, from->si_code)) {
3446	case SIL_KILL:
3447		to->si_pid = from->si_pid;
3448		to->si_uid = from->si_uid;
3449		break;
3450	case SIL_TIMER:
3451		to->si_tid     = from->si_tid;
3452		to->si_overrun = from->si_overrun;
3453		to->si_int     = from->si_int;
3454		break;
3455	case SIL_POLL:
3456		to->si_band = from->si_band;
3457		to->si_fd   = from->si_fd;
3458		break;
3459	case SIL_FAULT:
3460		to->si_addr = ptr_to_compat(from->si_addr);
3461		break;
3462	case SIL_FAULT_TRAPNO:
3463		to->si_addr = ptr_to_compat(from->si_addr);
3464		to->si_trapno = from->si_trapno;
3465		break;
3466	case SIL_FAULT_MCEERR:
3467		to->si_addr = ptr_to_compat(from->si_addr);
3468		to->si_addr_lsb = from->si_addr_lsb;
3469		break;
3470	case SIL_FAULT_BNDERR:
3471		to->si_addr = ptr_to_compat(from->si_addr);
3472		to->si_lower = ptr_to_compat(from->si_lower);
3473		to->si_upper = ptr_to_compat(from->si_upper);
3474		break;
3475	case SIL_FAULT_PKUERR:
3476		to->si_addr = ptr_to_compat(from->si_addr);
3477		to->si_pkey = from->si_pkey;
3478		break;
3479	case SIL_FAULT_PERF_EVENT:
3480		to->si_addr = ptr_to_compat(from->si_addr);
3481		to->si_perf_data = from->si_perf_data;
3482		to->si_perf_type = from->si_perf_type;
3483		to->si_perf_flags = from->si_perf_flags;
 
3484		break;
3485	case SIL_CHLD:
3486		to->si_pid = from->si_pid;
3487		to->si_uid = from->si_uid;
3488		to->si_status = from->si_status;
3489		to->si_utime = from->si_utime;
3490		to->si_stime = from->si_stime;
 
 
 
 
 
 
 
 
3491		break;
3492	case SIL_RT:
3493		to->si_pid = from->si_pid;
3494		to->si_uid = from->si_uid;
3495		to->si_int = from->si_int;
3496		break;
3497	case SIL_SYS:
3498		to->si_call_addr = ptr_to_compat(from->si_call_addr);
3499		to->si_syscall   = from->si_syscall;
3500		to->si_arch      = from->si_arch;
3501		break;
3502	}
3503}
3504
3505int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
3506			   const struct kernel_siginfo *from)
3507{
3508	struct compat_siginfo new;
3509
3510	copy_siginfo_to_external32(&new, from);
3511	if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
3512		return -EFAULT;
 
3513	return 0;
3514}
3515
3516static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
3517					 const struct compat_siginfo *from)
3518{
 
 
 
 
 
3519	clear_siginfo(to);
3520	to->si_signo = from->si_signo;
3521	to->si_errno = from->si_errno;
3522	to->si_code  = from->si_code;
3523	switch(siginfo_layout(from->si_signo, from->si_code)) {
3524	case SIL_KILL:
3525		to->si_pid = from->si_pid;
3526		to->si_uid = from->si_uid;
3527		break;
3528	case SIL_TIMER:
3529		to->si_tid     = from->si_tid;
3530		to->si_overrun = from->si_overrun;
3531		to->si_int     = from->si_int;
3532		break;
3533	case SIL_POLL:
3534		to->si_band = from->si_band;
3535		to->si_fd   = from->si_fd;
3536		break;
3537	case SIL_FAULT:
3538		to->si_addr = compat_ptr(from->si_addr);
3539		break;
3540	case SIL_FAULT_TRAPNO:
3541		to->si_addr = compat_ptr(from->si_addr);
3542		to->si_trapno = from->si_trapno;
3543		break;
3544	case SIL_FAULT_MCEERR:
3545		to->si_addr = compat_ptr(from->si_addr);
3546		to->si_addr_lsb = from->si_addr_lsb;
3547		break;
3548	case SIL_FAULT_BNDERR:
3549		to->si_addr = compat_ptr(from->si_addr);
3550		to->si_lower = compat_ptr(from->si_lower);
3551		to->si_upper = compat_ptr(from->si_upper);
3552		break;
3553	case SIL_FAULT_PKUERR:
3554		to->si_addr = compat_ptr(from->si_addr);
3555		to->si_pkey = from->si_pkey;
3556		break;
3557	case SIL_FAULT_PERF_EVENT:
3558		to->si_addr = compat_ptr(from->si_addr);
3559		to->si_perf_data = from->si_perf_data;
3560		to->si_perf_type = from->si_perf_type;
3561		to->si_perf_flags = from->si_perf_flags;
3562		break;
3563	case SIL_CHLD:
3564		to->si_pid    = from->si_pid;
3565		to->si_uid    = from->si_uid;
3566		to->si_status = from->si_status;
3567#ifdef CONFIG_X86_X32_ABI
3568		if (in_x32_syscall()) {
3569			to->si_utime = from->_sifields._sigchld_x32._utime;
3570			to->si_stime = from->_sifields._sigchld_x32._stime;
3571		} else
3572#endif
3573		{
3574			to->si_utime = from->si_utime;
3575			to->si_stime = from->si_stime;
3576		}
3577		break;
3578	case SIL_RT:
3579		to->si_pid = from->si_pid;
3580		to->si_uid = from->si_uid;
3581		to->si_int = from->si_int;
3582		break;
3583	case SIL_SYS:
3584		to->si_call_addr = compat_ptr(from->si_call_addr);
3585		to->si_syscall   = from->si_syscall;
3586		to->si_arch      = from->si_arch;
3587		break;
3588	}
3589	return 0;
3590}
3591
3592static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to,
3593				      const struct compat_siginfo __user *ufrom)
3594{
3595	struct compat_siginfo from;
3596
3597	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3598		return -EFAULT;
3599
3600	from.si_signo = signo;
3601	return post_copy_siginfo_from_user32(to, &from);
3602}
3603
3604int copy_siginfo_from_user32(struct kernel_siginfo *to,
3605			     const struct compat_siginfo __user *ufrom)
3606{
3607	struct compat_siginfo from;
3608
3609	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
3610		return -EFAULT;
3611
3612	return post_copy_siginfo_from_user32(to, &from);
3613}
3614#endif /* CONFIG_COMPAT */
3615
3616/**
3617 *  do_sigtimedwait - wait for queued signals specified in @which
3618 *  @which: queued signals to wait for
3619 *  @info: if non-null, the signal's siginfo is returned here
3620 *  @ts: upper bound on process time suspension
3621 */
3622static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
3623		    const struct timespec64 *ts)
3624{
3625	ktime_t *to = NULL, timeout = KTIME_MAX;
3626	struct task_struct *tsk = current;
3627	sigset_t mask = *which;
3628	enum pid_type type;
3629	int sig, ret = 0;
3630
3631	if (ts) {
3632		if (!timespec64_valid(ts))
3633			return -EINVAL;
3634		timeout = timespec64_to_ktime(*ts);
3635		to = &timeout;
3636	}
3637
3638	/*
3639	 * Invert the set of allowed signals to get those we want to block.
3640	 */
3641	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
3642	signotset(&mask);
3643
3644	spin_lock_irq(&tsk->sighand->siglock);
3645	sig = dequeue_signal(tsk, &mask, info, &type);
3646	if (!sig && timeout) {
3647		/*
3648		 * None ready, temporarily unblock those we're interested
3649		 * while we are sleeping in so that we'll be awakened when
3650		 * they arrive. Unblocking is always fine, we can avoid
3651		 * set_current_blocked().
3652		 */
3653		tsk->real_blocked = tsk->blocked;
3654		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
3655		recalc_sigpending();
3656		spin_unlock_irq(&tsk->sighand->siglock);
3657
3658		__set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
3659		ret = schedule_hrtimeout_range(to, tsk->timer_slack_ns,
3660					       HRTIMER_MODE_REL);
3661		spin_lock_irq(&tsk->sighand->siglock);
3662		__set_task_blocked(tsk, &tsk->real_blocked);
3663		sigemptyset(&tsk->real_blocked);
3664		sig = dequeue_signal(tsk, &mask, info, &type);
3665	}
3666	spin_unlock_irq(&tsk->sighand->siglock);
3667
3668	if (sig)
3669		return sig;
3670	return ret ? -EINTR : -EAGAIN;
3671}
3672
3673/**
3674 *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
3675 *			in @uthese
3676 *  @uthese: queued signals to wait for
3677 *  @uinfo: if non-null, the signal's siginfo is returned here
3678 *  @uts: upper bound on process time suspension
3679 *  @sigsetsize: size of sigset_t type
3680 */
3681SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
3682		siginfo_t __user *, uinfo,
3683		const struct __kernel_timespec __user *, uts,
3684		size_t, sigsetsize)
3685{
3686	sigset_t these;
3687	struct timespec64 ts;
3688	kernel_siginfo_t info;
3689	int ret;
3690
3691	/* XXX: Don't preclude handling different sized sigset_t's.  */
3692	if (sigsetsize != sizeof(sigset_t))
3693		return -EINVAL;
3694
3695	if (copy_from_user(&these, uthese, sizeof(these)))
3696		return -EFAULT;
3697
3698	if (uts) {
3699		if (get_timespec64(&ts, uts))
3700			return -EFAULT;
3701	}
3702
3703	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3704
3705	if (ret > 0 && uinfo) {
3706		if (copy_siginfo_to_user(uinfo, &info))
3707			ret = -EFAULT;
3708	}
3709
3710	return ret;
3711}
3712
3713#ifdef CONFIG_COMPAT_32BIT_TIME
3714SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese,
3715		siginfo_t __user *, uinfo,
3716		const struct old_timespec32 __user *, uts,
3717		size_t, sigsetsize)
3718{
3719	sigset_t these;
3720	struct timespec64 ts;
3721	kernel_siginfo_t info;
3722	int ret;
3723
3724	if (sigsetsize != sizeof(sigset_t))
3725		return -EINVAL;
3726
3727	if (copy_from_user(&these, uthese, sizeof(these)))
3728		return -EFAULT;
3729
3730	if (uts) {
3731		if (get_old_timespec32(&ts, uts))
3732			return -EFAULT;
3733	}
3734
3735	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
3736
3737	if (ret > 0 && uinfo) {
3738		if (copy_siginfo_to_user(uinfo, &info))
3739			ret = -EFAULT;
3740	}
3741
3742	return ret;
3743}
3744#endif
3745
3746#ifdef CONFIG_COMPAT
3747COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese,
3748		struct compat_siginfo __user *, uinfo,
3749		struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize)
3750{
3751	sigset_t s;
3752	struct timespec64 t;
3753	kernel_siginfo_t info;
3754	long ret;
3755
3756	if (sigsetsize != sizeof(sigset_t))
3757		return -EINVAL;
3758
3759	if (get_compat_sigset(&s, uthese))
3760		return -EFAULT;
3761
3762	if (uts) {
3763		if (get_timespec64(&t, uts))
3764			return -EFAULT;
3765	}
3766
3767	ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3768
3769	if (ret > 0 && uinfo) {
3770		if (copy_siginfo_to_user32(uinfo, &info))
3771			ret = -EFAULT;
3772	}
3773
3774	return ret;
3775}
3776
3777#ifdef CONFIG_COMPAT_32BIT_TIME
3778COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese,
3779		struct compat_siginfo __user *, uinfo,
3780		struct old_timespec32 __user *, uts, compat_size_t, sigsetsize)
3781{
3782	sigset_t s;
3783	struct timespec64 t;
3784	kernel_siginfo_t info;
3785	long ret;
3786
3787	if (sigsetsize != sizeof(sigset_t))
3788		return -EINVAL;
3789
3790	if (get_compat_sigset(&s, uthese))
3791		return -EFAULT;
3792
3793	if (uts) {
3794		if (get_old_timespec32(&t, uts))
3795			return -EFAULT;
3796	}
3797
3798	ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);
3799
3800	if (ret > 0 && uinfo) {
3801		if (copy_siginfo_to_user32(uinfo, &info))
3802			ret = -EFAULT;
3803	}
3804
3805	return ret;
3806}
3807#endif
3808#endif
3809
3810static void prepare_kill_siginfo(int sig, struct kernel_siginfo *info,
3811				 enum pid_type type)
3812{
3813	clear_siginfo(info);
3814	info->si_signo = sig;
3815	info->si_errno = 0;
3816	info->si_code = (type == PIDTYPE_PID) ? SI_TKILL : SI_USER;
3817	info->si_pid = task_tgid_vnr(current);
3818	info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
3819}
3820
3821/**
3822 *  sys_kill - send a signal to a process
3823 *  @pid: the PID of the process
3824 *  @sig: signal to be sent
3825 */
3826SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
3827{
3828	struct kernel_siginfo info;
3829
3830	prepare_kill_siginfo(sig, &info, PIDTYPE_TGID);
 
 
 
 
 
3831
3832	return kill_something_info(sig, &info, pid);
3833}
3834
3835/*
3836 * Verify that the signaler and signalee either are in the same pid namespace
3837 * or that the signaler's pid namespace is an ancestor of the signalee's pid
3838 * namespace.
3839 */
3840static bool access_pidfd_pidns(struct pid *pid)
3841{
3842	struct pid_namespace *active = task_active_pid_ns(current);
3843	struct pid_namespace *p = ns_of_pid(pid);
3844
3845	for (;;) {
3846		if (!p)
3847			return false;
3848		if (p == active)
3849			break;
3850		p = p->parent;
3851	}
3852
3853	return true;
3854}
3855
3856static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
3857		siginfo_t __user *info)
3858{
3859#ifdef CONFIG_COMPAT
3860	/*
3861	 * Avoid hooking up compat syscalls and instead handle necessary
3862	 * conversions here. Note, this is a stop-gap measure and should not be
3863	 * considered a generic solution.
3864	 */
3865	if (in_compat_syscall())
3866		return copy_siginfo_from_user32(
3867			kinfo, (struct compat_siginfo __user *)info);
3868#endif
3869	return copy_siginfo_from_user(kinfo, info);
3870}
3871
3872static struct pid *pidfd_to_pid(const struct file *file)
3873{
3874	struct pid *pid;
3875
3876	pid = pidfd_pid(file);
3877	if (!IS_ERR(pid))
3878		return pid;
3879
3880	return tgid_pidfd_to_pid(file);
3881}
3882
3883#define PIDFD_SEND_SIGNAL_FLAGS                            \
3884	(PIDFD_SIGNAL_THREAD | PIDFD_SIGNAL_THREAD_GROUP | \
3885	 PIDFD_SIGNAL_PROCESS_GROUP)
3886
3887/**
3888 * sys_pidfd_send_signal - Signal a process through a pidfd
3889 * @pidfd:  file descriptor of the process
3890 * @sig:    signal to send
3891 * @info:   signal info
3892 * @flags:  future flags
3893 *
3894 * Send the signal to the thread group or to the individual thread depending
3895 * on PIDFD_THREAD.
3896 * In the future extension to @flags may be used to override the default scope
3897 * of @pidfd.
3898 *
3899 * Return: 0 on success, negative errno on failure
3900 */
3901SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
3902		siginfo_t __user *, info, unsigned int, flags)
3903{
3904	int ret;
3905	struct fd f;
3906	struct pid *pid;
3907	kernel_siginfo_t kinfo;
3908	enum pid_type type;
3909
3910	/* Enforce flags be set to 0 until we add an extension. */
3911	if (flags & ~PIDFD_SEND_SIGNAL_FLAGS)
3912		return -EINVAL;
3913
3914	/* Ensure that only a single signal scope determining flag is set. */
3915	if (hweight32(flags & PIDFD_SEND_SIGNAL_FLAGS) > 1)
3916		return -EINVAL;
3917
3918	f = fdget(pidfd);
3919	if (!f.file)
3920		return -EBADF;
3921
3922	/* Is this a pidfd? */
3923	pid = pidfd_to_pid(f.file);
3924	if (IS_ERR(pid)) {
3925		ret = PTR_ERR(pid);
3926		goto err;
3927	}
3928
3929	ret = -EINVAL;
3930	if (!access_pidfd_pidns(pid))
3931		goto err;
3932
3933	switch (flags) {
3934	case 0:
3935		/* Infer scope from the type of pidfd. */
3936		if (f.file->f_flags & PIDFD_THREAD)
3937			type = PIDTYPE_PID;
3938		else
3939			type = PIDTYPE_TGID;
3940		break;
3941	case PIDFD_SIGNAL_THREAD:
3942		type = PIDTYPE_PID;
3943		break;
3944	case PIDFD_SIGNAL_THREAD_GROUP:
3945		type = PIDTYPE_TGID;
3946		break;
3947	case PIDFD_SIGNAL_PROCESS_GROUP:
3948		type = PIDTYPE_PGID;
3949		break;
3950	}
3951
3952	if (info) {
3953		ret = copy_siginfo_from_user_any(&kinfo, info);
3954		if (unlikely(ret))
3955			goto err;
3956
3957		ret = -EINVAL;
3958		if (unlikely(sig != kinfo.si_signo))
3959			goto err;
3960
3961		/* Only allow sending arbitrary signals to yourself. */
3962		ret = -EPERM;
3963		if ((task_pid(current) != pid || type > PIDTYPE_TGID) &&
3964		    (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL))
3965			goto err;
3966	} else {
3967		prepare_kill_siginfo(sig, &kinfo, type);
3968	}
3969
3970	if (type == PIDTYPE_PGID)
3971		ret = kill_pgrp_info(sig, &kinfo, pid);
3972	else
3973		ret = kill_pid_info_type(sig, &kinfo, pid, type);
3974err:
3975	fdput(f);
3976	return ret;
3977}
3978
3979static int
3980do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
3981{
3982	struct task_struct *p;
3983	int error = -ESRCH;
3984
3985	rcu_read_lock();
3986	p = find_task_by_vpid(pid);
3987	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
3988		error = check_kill_permission(sig, info, p);
3989		/*
3990		 * The null signal is a permissions and process existence
3991		 * probe.  No signal is actually delivered.
3992		 */
3993		if (!error && sig) {
3994			error = do_send_sig_info(sig, info, p, PIDTYPE_PID);
3995			/*
3996			 * If lock_task_sighand() failed we pretend the task
3997			 * dies after receiving the signal. The window is tiny,
3998			 * and the signal is private anyway.
3999			 */
4000			if (unlikely(error == -ESRCH))
4001				error = 0;
4002		}
4003	}
4004	rcu_read_unlock();
4005
4006	return error;
4007}
4008
4009static int do_tkill(pid_t tgid, pid_t pid, int sig)
4010{
4011	struct kernel_siginfo info;
4012
4013	prepare_kill_siginfo(sig, &info, PIDTYPE_PID);
 
 
 
 
 
4014
4015	return do_send_specific(tgid, pid, sig, &info);
4016}
4017
4018/**
4019 *  sys_tgkill - send signal to one specific thread
4020 *  @tgid: the thread group ID of the thread
4021 *  @pid: the PID of the thread
4022 *  @sig: signal to be sent
4023 *
4024 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
4025 *  exists but it's not belonging to the target process anymore. This
4026 *  method solves the problem of threads exiting and PIDs getting reused.
4027 */
4028SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
4029{
4030	/* This is only valid for single tasks */
4031	if (pid <= 0 || tgid <= 0)
4032		return -EINVAL;
4033
4034	return do_tkill(tgid, pid, sig);
4035}
4036
4037/**
4038 *  sys_tkill - send signal to one specific task
4039 *  @pid: the PID of the task
4040 *  @sig: signal to be sent
4041 *
4042 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
4043 */
4044SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
4045{
4046	/* This is only valid for single tasks */
4047	if (pid <= 0)
4048		return -EINVAL;
4049
4050	return do_tkill(0, pid, sig);
4051}
4052
4053static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info)
4054{
4055	/* Not even root can pretend to send signals from the kernel.
4056	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4057	 */
4058	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4059	    (task_pid_vnr(current) != pid))
4060		return -EPERM;
4061
 
 
4062	/* POSIX.1b doesn't mention process groups.  */
4063	return kill_proc_info(sig, info, pid);
4064}
4065
4066/**
4067 *  sys_rt_sigqueueinfo - send signal information to a signal
4068 *  @pid: the PID of the thread
4069 *  @sig: signal to be sent
4070 *  @uinfo: signal info to be sent
4071 */
4072SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
4073		siginfo_t __user *, uinfo)
4074{
4075	kernel_siginfo_t info;
4076	int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4077	if (unlikely(ret))
4078		return ret;
4079	return do_rt_sigqueueinfo(pid, sig, &info);
4080}
4081
4082#ifdef CONFIG_COMPAT
4083COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
4084			compat_pid_t, pid,
4085			int, sig,
4086			struct compat_siginfo __user *, uinfo)
4087{
4088	kernel_siginfo_t info;
4089	int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4090	if (unlikely(ret))
4091		return ret;
4092	return do_rt_sigqueueinfo(pid, sig, &info);
4093}
4094#endif
4095
4096static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info)
4097{
4098	/* This is only valid for single tasks */
4099	if (pid <= 0 || tgid <= 0)
4100		return -EINVAL;
4101
4102	/* Not even root can pretend to send signals from the kernel.
4103	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
4104	 */
4105	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
4106	    (task_pid_vnr(current) != pid))
4107		return -EPERM;
4108
 
 
4109	return do_send_specific(tgid, pid, sig, info);
4110}
4111
4112SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
4113		siginfo_t __user *, uinfo)
4114{
4115	kernel_siginfo_t info;
4116	int ret = __copy_siginfo_from_user(sig, &info, uinfo);
4117	if (unlikely(ret))
4118		return ret;
 
4119	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4120}
4121
4122#ifdef CONFIG_COMPAT
4123COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
4124			compat_pid_t, tgid,
4125			compat_pid_t, pid,
4126			int, sig,
4127			struct compat_siginfo __user *, uinfo)
4128{
4129	kernel_siginfo_t info;
4130	int ret = __copy_siginfo_from_user32(sig, &info, uinfo);
4131	if (unlikely(ret))
4132		return ret;
4133	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
4134}
4135#endif
4136
4137/*
4138 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
4139 */
4140void kernel_sigaction(int sig, __sighandler_t action)
4141{
4142	spin_lock_irq(&current->sighand->siglock);
4143	current->sighand->action[sig - 1].sa.sa_handler = action;
4144	if (action == SIG_IGN) {
4145		sigset_t mask;
4146
4147		sigemptyset(&mask);
4148		sigaddset(&mask, sig);
4149
4150		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
4151		flush_sigqueue_mask(&mask, &current->pending);
4152		recalc_sigpending();
4153	}
4154	spin_unlock_irq(&current->sighand->siglock);
4155}
4156EXPORT_SYMBOL(kernel_sigaction);
4157
4158void __weak sigaction_compat_abi(struct k_sigaction *act,
4159		struct k_sigaction *oact)
4160{
4161}
4162
4163int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
4164{
4165	struct task_struct *p = current, *t;
4166	struct k_sigaction *k;
4167	sigset_t mask;
4168
4169	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
4170		return -EINVAL;
4171
4172	k = &p->sighand->action[sig-1];
4173
4174	spin_lock_irq(&p->sighand->siglock);
4175	if (k->sa.sa_flags & SA_IMMUTABLE) {
4176		spin_unlock_irq(&p->sighand->siglock);
4177		return -EINVAL;
4178	}
4179	if (oact)
4180		*oact = *k;
4181
4182	/*
4183	 * Make sure that we never accidentally claim to support SA_UNSUPPORTED,
4184	 * e.g. by having an architecture use the bit in their uapi.
4185	 */
4186	BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED);
4187
4188	/*
4189	 * Clear unknown flag bits in order to allow userspace to detect missing
4190	 * support for flag bits and to allow the kernel to use non-uapi bits
4191	 * internally.
4192	 */
4193	if (act)
4194		act->sa.sa_flags &= UAPI_SA_FLAGS;
4195	if (oact)
4196		oact->sa.sa_flags &= UAPI_SA_FLAGS;
4197
4198	sigaction_compat_abi(act, oact);
4199
4200	if (act) {
4201		sigdelsetmask(&act->sa.sa_mask,
4202			      sigmask(SIGKILL) | sigmask(SIGSTOP));
4203		*k = *act;
4204		/*
4205		 * POSIX 3.3.1.3:
4206		 *  "Setting a signal action to SIG_IGN for a signal that is
4207		 *   pending shall cause the pending signal to be discarded,
4208		 *   whether or not it is blocked."
4209		 *
4210		 *  "Setting a signal action to SIG_DFL for a signal that is
4211		 *   pending and whose default action is to ignore the signal
4212		 *   (for example, SIGCHLD), shall cause the pending signal to
4213		 *   be discarded, whether or not it is blocked"
4214		 */
4215		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
4216			sigemptyset(&mask);
4217			sigaddset(&mask, sig);
4218			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
4219			for_each_thread(p, t)
4220				flush_sigqueue_mask(&mask, &t->pending);
4221		}
4222	}
4223
4224	spin_unlock_irq(&p->sighand->siglock);
4225	return 0;
4226}
4227
4228#ifdef CONFIG_DYNAMIC_SIGFRAME
4229static inline void sigaltstack_lock(void)
4230	__acquires(&current->sighand->siglock)
4231{
4232	spin_lock_irq(&current->sighand->siglock);
4233}
4234
4235static inline void sigaltstack_unlock(void)
4236	__releases(&current->sighand->siglock)
4237{
4238	spin_unlock_irq(&current->sighand->siglock);
4239}
4240#else
4241static inline void sigaltstack_lock(void) { }
4242static inline void sigaltstack_unlock(void) { }
4243#endif
4244
4245static int
4246do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
4247		size_t min_ss_size)
4248{
4249	struct task_struct *t = current;
4250	int ret = 0;
4251
4252	if (oss) {
4253		memset(oss, 0, sizeof(stack_t));
4254		oss->ss_sp = (void __user *) t->sas_ss_sp;
4255		oss->ss_size = t->sas_ss_size;
4256		oss->ss_flags = sas_ss_flags(sp) |
4257			(current->sas_ss_flags & SS_FLAG_BITS);
4258	}
4259
4260	if (ss) {
4261		void __user *ss_sp = ss->ss_sp;
4262		size_t ss_size = ss->ss_size;
4263		unsigned ss_flags = ss->ss_flags;
4264		int ss_mode;
4265
4266		if (unlikely(on_sig_stack(sp)))
4267			return -EPERM;
4268
4269		ss_mode = ss_flags & ~SS_FLAG_BITS;
4270		if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
4271				ss_mode != 0))
4272			return -EINVAL;
4273
4274		/*
4275		 * Return before taking any locks if no actual
4276		 * sigaltstack changes were requested.
4277		 */
4278		if (t->sas_ss_sp == (unsigned long)ss_sp &&
4279		    t->sas_ss_size == ss_size &&
4280		    t->sas_ss_flags == ss_flags)
4281			return 0;
4282
4283		sigaltstack_lock();
4284		if (ss_mode == SS_DISABLE) {
4285			ss_size = 0;
4286			ss_sp = NULL;
4287		} else {
4288			if (unlikely(ss_size < min_ss_size))
4289				ret = -ENOMEM;
4290			if (!sigaltstack_size_valid(ss_size))
4291				ret = -ENOMEM;
4292		}
4293		if (!ret) {
4294			t->sas_ss_sp = (unsigned long) ss_sp;
4295			t->sas_ss_size = ss_size;
4296			t->sas_ss_flags = ss_flags;
4297		}
4298		sigaltstack_unlock();
4299	}
4300	return ret;
4301}
4302
4303SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
4304{
4305	stack_t new, old;
4306	int err;
4307	if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
4308		return -EFAULT;
4309	err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
4310			      current_user_stack_pointer(),
4311			      MINSIGSTKSZ);
4312	if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
4313		err = -EFAULT;
4314	return err;
4315}
4316
4317int restore_altstack(const stack_t __user *uss)
4318{
4319	stack_t new;
4320	if (copy_from_user(&new, uss, sizeof(stack_t)))
4321		return -EFAULT;
4322	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
4323			     MINSIGSTKSZ);
4324	/* squash all but EFAULT for now */
4325	return 0;
4326}
4327
4328int __save_altstack(stack_t __user *uss, unsigned long sp)
4329{
4330	struct task_struct *t = current;
4331	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
4332		__put_user(t->sas_ss_flags, &uss->ss_flags) |
4333		__put_user(t->sas_ss_size, &uss->ss_size);
4334	return err;
 
 
 
 
4335}
4336
4337#ifdef CONFIG_COMPAT
4338static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
4339				 compat_stack_t __user *uoss_ptr)
4340{
4341	stack_t uss, uoss;
4342	int ret;
4343
4344	if (uss_ptr) {
4345		compat_stack_t uss32;
4346		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
4347			return -EFAULT;
4348		uss.ss_sp = compat_ptr(uss32.ss_sp);
4349		uss.ss_flags = uss32.ss_flags;
4350		uss.ss_size = uss32.ss_size;
4351	}
4352	ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
4353			     compat_user_stack_pointer(),
4354			     COMPAT_MINSIGSTKSZ);
4355	if (ret >= 0 && uoss_ptr)  {
4356		compat_stack_t old;
4357		memset(&old, 0, sizeof(old));
4358		old.ss_sp = ptr_to_compat(uoss.ss_sp);
4359		old.ss_flags = uoss.ss_flags;
4360		old.ss_size = uoss.ss_size;
4361		if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
4362			ret = -EFAULT;
4363	}
4364	return ret;
4365}
4366
4367COMPAT_SYSCALL_DEFINE2(sigaltstack,
4368			const compat_stack_t __user *, uss_ptr,
4369			compat_stack_t __user *, uoss_ptr)
4370{
4371	return do_compat_sigaltstack(uss_ptr, uoss_ptr);
4372}
4373
4374int compat_restore_altstack(const compat_stack_t __user *uss)
4375{
4376	int err = do_compat_sigaltstack(uss, NULL);
4377	/* squash all but -EFAULT for now */
4378	return err == -EFAULT ? err : 0;
4379}
4380
4381int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
4382{
4383	int err;
4384	struct task_struct *t = current;
4385	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
4386			 &uss->ss_sp) |
4387		__put_user(t->sas_ss_flags, &uss->ss_flags) |
4388		__put_user(t->sas_ss_size, &uss->ss_size);
4389	return err;
 
 
 
 
4390}
4391#endif
4392
4393#ifdef __ARCH_WANT_SYS_SIGPENDING
4394
4395/**
4396 *  sys_sigpending - examine pending signals
4397 *  @uset: where mask of pending signal is returned
4398 */
4399SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
4400{
4401	sigset_t set;
 
4402
4403	if (sizeof(old_sigset_t) > sizeof(*uset))
4404		return -EINVAL;
4405
4406	do_sigpending(&set);
4407
4408	if (copy_to_user(uset, &set, sizeof(old_sigset_t)))
4409		return -EFAULT;
4410
4411	return 0;
4412}
4413
4414#ifdef CONFIG_COMPAT
4415COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
4416{
4417	sigset_t set;
4418
4419	do_sigpending(&set);
4420
4421	return put_user(set.sig[0], set32);
4422}
4423#endif
4424
4425#endif
4426
4427#ifdef __ARCH_WANT_SYS_SIGPROCMASK
4428/**
4429 *  sys_sigprocmask - examine and change blocked signals
4430 *  @how: whether to add, remove, or set signals
4431 *  @nset: signals to add or remove (if non-null)
4432 *  @oset: previous value of signal mask if non-null
4433 *
4434 * Some platforms have their own version with special arguments;
4435 * others support only sys_rt_sigprocmask.
4436 */
4437
4438SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
4439		old_sigset_t __user *, oset)
4440{
4441	old_sigset_t old_set, new_set;
4442	sigset_t new_blocked;
4443
4444	old_set = current->blocked.sig[0];
4445
4446	if (nset) {
4447		if (copy_from_user(&new_set, nset, sizeof(*nset)))
4448			return -EFAULT;
4449
4450		new_blocked = current->blocked;
4451
4452		switch (how) {
4453		case SIG_BLOCK:
4454			sigaddsetmask(&new_blocked, new_set);
4455			break;
4456		case SIG_UNBLOCK:
4457			sigdelsetmask(&new_blocked, new_set);
4458			break;
4459		case SIG_SETMASK:
4460			new_blocked.sig[0] = new_set;
4461			break;
4462		default:
4463			return -EINVAL;
4464		}
4465
4466		set_current_blocked(&new_blocked);
4467	}
4468
4469	if (oset) {
4470		if (copy_to_user(oset, &old_set, sizeof(*oset)))
4471			return -EFAULT;
4472	}
4473
4474	return 0;
4475}
4476#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
4477
4478#ifndef CONFIG_ODD_RT_SIGACTION
4479/**
4480 *  sys_rt_sigaction - alter an action taken by a process
4481 *  @sig: signal to be sent
4482 *  @act: new sigaction
4483 *  @oact: used to save the previous sigaction
4484 *  @sigsetsize: size of sigset_t type
4485 */
4486SYSCALL_DEFINE4(rt_sigaction, int, sig,
4487		const struct sigaction __user *, act,
4488		struct sigaction __user *, oact,
4489		size_t, sigsetsize)
4490{
4491	struct k_sigaction new_sa, old_sa;
4492	int ret;
4493
4494	/* XXX: Don't preclude handling different sized sigset_t's.  */
4495	if (sigsetsize != sizeof(sigset_t))
4496		return -EINVAL;
4497
4498	if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
4499		return -EFAULT;
 
 
4500
4501	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
4502	if (ret)
4503		return ret;
4504
4505	if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
4506		return -EFAULT;
4507
4508	return 0;
 
 
4509}
4510#ifdef CONFIG_COMPAT
4511COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
4512		const struct compat_sigaction __user *, act,
4513		struct compat_sigaction __user *, oact,
4514		compat_size_t, sigsetsize)
4515{
4516	struct k_sigaction new_ka, old_ka;
4517#ifdef __ARCH_HAS_SA_RESTORER
4518	compat_uptr_t restorer;
4519#endif
4520	int ret;
4521
4522	/* XXX: Don't preclude handling different sized sigset_t's.  */
4523	if (sigsetsize != sizeof(compat_sigset_t))
4524		return -EINVAL;
4525
4526	if (act) {
4527		compat_uptr_t handler;
4528		ret = get_user(handler, &act->sa_handler);
4529		new_ka.sa.sa_handler = compat_ptr(handler);
4530#ifdef __ARCH_HAS_SA_RESTORER
4531		ret |= get_user(restorer, &act->sa_restorer);
4532		new_ka.sa.sa_restorer = compat_ptr(restorer);
4533#endif
4534		ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
4535		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
4536		if (ret)
4537			return -EFAULT;
4538	}
4539
4540	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4541	if (!ret && oact) {
4542		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
4543			       &oact->sa_handler);
4544		ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
4545					 sizeof(oact->sa_mask));
4546		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
4547#ifdef __ARCH_HAS_SA_RESTORER
4548		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4549				&oact->sa_restorer);
4550#endif
4551	}
4552	return ret;
4553}
4554#endif
4555#endif /* !CONFIG_ODD_RT_SIGACTION */
4556
4557#ifdef CONFIG_OLD_SIGACTION
4558SYSCALL_DEFINE3(sigaction, int, sig,
4559		const struct old_sigaction __user *, act,
4560	        struct old_sigaction __user *, oact)
4561{
4562	struct k_sigaction new_ka, old_ka;
4563	int ret;
4564
4565	if (act) {
4566		old_sigset_t mask;
4567		if (!access_ok(act, sizeof(*act)) ||
4568		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
4569		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
4570		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4571		    __get_user(mask, &act->sa_mask))
4572			return -EFAULT;
4573#ifdef __ARCH_HAS_KA_RESTORER
4574		new_ka.ka_restorer = NULL;
4575#endif
4576		siginitset(&new_ka.sa.sa_mask, mask);
4577	}
4578
4579	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4580
4581	if (!ret && oact) {
4582		if (!access_ok(oact, sizeof(*oact)) ||
4583		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
4584		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
4585		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4586		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4587			return -EFAULT;
4588	}
4589
4590	return ret;
4591}
4592#endif
4593#ifdef CONFIG_COMPAT_OLD_SIGACTION
4594COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
4595		const struct compat_old_sigaction __user *, act,
4596	        struct compat_old_sigaction __user *, oact)
4597{
4598	struct k_sigaction new_ka, old_ka;
4599	int ret;
4600	compat_old_sigset_t mask;
4601	compat_uptr_t handler, restorer;
4602
4603	if (act) {
4604		if (!access_ok(act, sizeof(*act)) ||
4605		    __get_user(handler, &act->sa_handler) ||
4606		    __get_user(restorer, &act->sa_restorer) ||
4607		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
4608		    __get_user(mask, &act->sa_mask))
4609			return -EFAULT;
4610
4611#ifdef __ARCH_HAS_KA_RESTORER
4612		new_ka.ka_restorer = NULL;
4613#endif
4614		new_ka.sa.sa_handler = compat_ptr(handler);
4615		new_ka.sa.sa_restorer = compat_ptr(restorer);
4616		siginitset(&new_ka.sa.sa_mask, mask);
4617	}
4618
4619	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
4620
4621	if (!ret && oact) {
4622		if (!access_ok(oact, sizeof(*oact)) ||
4623		    __put_user(ptr_to_compat(old_ka.sa.sa_handler),
4624			       &oact->sa_handler) ||
4625		    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
4626			       &oact->sa_restorer) ||
4627		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
4628		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
4629			return -EFAULT;
4630	}
4631	return ret;
4632}
4633#endif
4634
4635#ifdef CONFIG_SGETMASK_SYSCALL
4636
4637/*
4638 * For backwards compatibility.  Functionality superseded by sigprocmask.
4639 */
4640SYSCALL_DEFINE0(sgetmask)
4641{
4642	/* SMP safe */
4643	return current->blocked.sig[0];
4644}
4645
4646SYSCALL_DEFINE1(ssetmask, int, newmask)
4647{
4648	int old = current->blocked.sig[0];
4649	sigset_t newset;
4650
4651	siginitset(&newset, newmask);
4652	set_current_blocked(&newset);
4653
4654	return old;
4655}
4656#endif /* CONFIG_SGETMASK_SYSCALL */
4657
4658#ifdef __ARCH_WANT_SYS_SIGNAL
4659/*
4660 * For backwards compatibility.  Functionality superseded by sigaction.
4661 */
4662SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
4663{
4664	struct k_sigaction new_sa, old_sa;
4665	int ret;
4666
4667	new_sa.sa.sa_handler = handler;
4668	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
4669	sigemptyset(&new_sa.sa.sa_mask);
4670
4671	ret = do_sigaction(sig, &new_sa, &old_sa);
4672
4673	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
4674}
4675#endif /* __ARCH_WANT_SYS_SIGNAL */
4676
4677#ifdef __ARCH_WANT_SYS_PAUSE
4678
4679SYSCALL_DEFINE0(pause)
4680{
4681	while (!signal_pending(current)) {
4682		__set_current_state(TASK_INTERRUPTIBLE);
4683		schedule();
4684	}
4685	return -ERESTARTNOHAND;
4686}
4687
4688#endif
4689
4690static int sigsuspend(sigset_t *set)
4691{
4692	current->saved_sigmask = current->blocked;
4693	set_current_blocked(set);
4694
4695	while (!signal_pending(current)) {
4696		__set_current_state(TASK_INTERRUPTIBLE);
4697		schedule();
4698	}
4699	set_restore_sigmask();
4700	return -ERESTARTNOHAND;
4701}
4702
4703/**
4704 *  sys_rt_sigsuspend - replace the signal mask for a value with the
4705 *	@unewset value until a signal is received
4706 *  @unewset: new signal mask value
4707 *  @sigsetsize: size of sigset_t type
4708 */
4709SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
4710{
4711	sigset_t newset;
4712
4713	/* XXX: Don't preclude handling different sized sigset_t's.  */
4714	if (sigsetsize != sizeof(sigset_t))
4715		return -EINVAL;
4716
4717	if (copy_from_user(&newset, unewset, sizeof(newset)))
4718		return -EFAULT;
4719	return sigsuspend(&newset);
4720}
4721 
4722#ifdef CONFIG_COMPAT
4723COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
4724{
4725	sigset_t newset;
4726
4727	/* XXX: Don't preclude handling different sized sigset_t's.  */
4728	if (sigsetsize != sizeof(sigset_t))
4729		return -EINVAL;
4730
4731	if (get_compat_sigset(&newset, unewset))
4732		return -EFAULT;
4733	return sigsuspend(&newset);
4734}
4735#endif
4736
4737#ifdef CONFIG_OLD_SIGSUSPEND
4738SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
4739{
4740	sigset_t blocked;
4741	siginitset(&blocked, mask);
4742	return sigsuspend(&blocked);
4743}
4744#endif
4745#ifdef CONFIG_OLD_SIGSUSPEND3
4746SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
4747{
4748	sigset_t blocked;
4749	siginitset(&blocked, mask);
4750	return sigsuspend(&blocked);
4751}
4752#endif
4753
4754__weak const char *arch_vma_name(struct vm_area_struct *vma)
4755{
4756	return NULL;
4757}
4758
4759static inline void siginfo_buildtime_checks(void)
4760{
 
 
 
4761	BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
4762
4763	/* Verify the offsets in the two siginfos match */
4764#define CHECK_OFFSET(field) \
4765	BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field))
4766
4767	/* kill */
4768	CHECK_OFFSET(si_pid);
4769	CHECK_OFFSET(si_uid);
4770
4771	/* timer */
4772	CHECK_OFFSET(si_tid);
4773	CHECK_OFFSET(si_overrun);
4774	CHECK_OFFSET(si_value);
4775
4776	/* rt */
4777	CHECK_OFFSET(si_pid);
4778	CHECK_OFFSET(si_uid);
4779	CHECK_OFFSET(si_value);
4780
4781	/* sigchld */
4782	CHECK_OFFSET(si_pid);
4783	CHECK_OFFSET(si_uid);
4784	CHECK_OFFSET(si_status);
4785	CHECK_OFFSET(si_utime);
4786	CHECK_OFFSET(si_stime);
4787
4788	/* sigfault */
4789	CHECK_OFFSET(si_addr);
4790	CHECK_OFFSET(si_trapno);
4791	CHECK_OFFSET(si_addr_lsb);
4792	CHECK_OFFSET(si_lower);
4793	CHECK_OFFSET(si_upper);
4794	CHECK_OFFSET(si_pkey);
4795	CHECK_OFFSET(si_perf_data);
4796	CHECK_OFFSET(si_perf_type);
4797	CHECK_OFFSET(si_perf_flags);
4798
4799	/* sigpoll */
4800	CHECK_OFFSET(si_band);
4801	CHECK_OFFSET(si_fd);
4802
4803	/* sigsys */
4804	CHECK_OFFSET(si_call_addr);
4805	CHECK_OFFSET(si_syscall);
4806	CHECK_OFFSET(si_arch);
4807#undef CHECK_OFFSET
4808
4809	/* usb asyncio */
4810	BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
4811		     offsetof(struct siginfo, si_addr));
4812	if (sizeof(int) == sizeof(void __user *)) {
4813		BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
4814			     sizeof(void __user *));
4815	} else {
4816		BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
4817			      sizeof_field(struct siginfo, si_uid)) !=
4818			     sizeof(void __user *));
4819		BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
4820			     offsetof(struct siginfo, si_uid));
4821	}
4822#ifdef CONFIG_COMPAT
4823	BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
4824		     offsetof(struct compat_siginfo, si_addr));
4825	BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4826		     sizeof(compat_uptr_t));
4827	BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
4828		     sizeof_field(struct siginfo, si_pid));
4829#endif
4830}
4831
4832#if defined(CONFIG_SYSCTL)
4833static struct ctl_table signal_debug_table[] = {
4834#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
4835	{
4836		.procname	= "exception-trace",
4837		.data		= &show_unhandled_signals,
4838		.maxlen		= sizeof(int),
4839		.mode		= 0644,
4840		.proc_handler	= proc_dointvec
4841	},
4842#endif
4843	{ }
4844};
4845
4846static int __init init_signal_sysctls(void)
4847{
4848	register_sysctl_init("debug", signal_debug_table);
4849	return 0;
4850}
4851early_initcall(init_signal_sysctls);
4852#endif /* CONFIG_SYSCTL */
4853
4854void __init signals_init(void)
4855{
4856	siginfo_buildtime_checks();
4857
4858	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
4859}
4860
4861#ifdef CONFIG_KGDB_KDB
4862#include <linux/kdb.h>
4863/*
4864 * kdb_send_sig - Allows kdb to send signals without exposing
4865 * signal internals.  This function checks if the required locks are
4866 * available before calling the main signal code, to avoid kdb
4867 * deadlocks.
4868 */
4869void kdb_send_sig(struct task_struct *t, int sig)
4870{
4871	static struct task_struct *kdb_prev_t;
4872	int new_t, ret;
4873	if (!spin_trylock(&t->sighand->siglock)) {
4874		kdb_printf("Can't do kill command now.\n"
4875			   "The sigmask lock is held somewhere else in "
4876			   "kernel, try again later\n");
4877		return;
4878	}
4879	new_t = kdb_prev_t != t;
4880	kdb_prev_t = t;
4881	if (!task_is_running(t) && new_t) {
4882		spin_unlock(&t->sighand->siglock);
4883		kdb_printf("Process is not RUNNING, sending a signal from "
4884			   "kdb risks deadlock\n"
4885			   "on the run queue locks. "
4886			   "The signal has _not_ been sent.\n"
4887			   "Reissue the kill command if you want to risk "
4888			   "the deadlock.\n");
4889		return;
4890	}
4891	ret = send_signal_locked(sig, SEND_SIG_PRIV, t, PIDTYPE_PID);
4892	spin_unlock(&t->sighand->siglock);
4893	if (ret)
4894		kdb_printf("Fail to deliver Signal %d to process %d.\n",
4895			   sig, t->pid);
4896	else
4897		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
4898}
4899#endif	/* CONFIG_KGDB_KDB */