signal.c 95.7 KB
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/*
 *  linux/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
 *
 *  2003-06-02  Jim Houston - Concurrent Computer Corp.
 *		Changes to use preallocated sigqueue structures
 *		to allow signals to be sent reliably.
 */

#include <linux/slab.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/user.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/task.h>
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#include <linux/sched/task_stack.h>
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#include <linux/sched/cputime.h>
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#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
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#include <linux/coredump.h>
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#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/ptrace.h>
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#include <linux/signal.h>
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#include <linux/signalfd.h>
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#include <linux/ratelimit.h>
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#include <linux/tracehook.h>
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#include <linux/capability.h>
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#include <linux/freezer.h>
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#include <linux/pid_namespace.h>
#include <linux/nsproxy.h>
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#include <linux/user_namespace.h>
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#include <linux/uprobes.h>
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#include <linux/compat.h>
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#include <linux/cn_proc.h>
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#include <linux/compiler.h>
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#include <linux/posix-timers.h>
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#define CREATE_TRACE_POINTS
#include <trace/events/signal.h>
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#include <asm/param.h>
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#include <linux/uaccess.h>
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#include <asm/unistd.h>
#include <asm/siginfo.h>
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#include <asm/cacheflush.h>
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#include "audit.h"	/* audit_signal_info() */
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/*
 * SLAB caches for signal bits.
 */

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static struct kmem_cache *sigqueue_cachep;
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int print_fatal_signals __read_mostly;

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static void __user *sig_handler(struct task_struct *t, int sig)
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{
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	return t->sighand->action[sig - 1].sa.sa_handler;
}
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static int sig_handler_ignored(void __user *handler, int sig)
{
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	/* Is it explicitly or implicitly ignored? */
	return handler == SIG_IGN ||
		(handler == SIG_DFL && sig_kernel_ignore(sig));
}
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static int sig_task_ignored(struct task_struct *t, int sig, bool force)
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{
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	void __user *handler;
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	handler = sig_handler(t, sig);

	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
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			handler == SIG_DFL && !force)
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		return 1;

	return sig_handler_ignored(handler, sig);
}

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static int sig_ignored(struct task_struct *t, int sig, bool force)
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{
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	/*
	 * Blocked signals are never ignored, since the
	 * signal handler may change by the time it is
	 * unblocked.
	 */
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	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
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		return 0;

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	if (!sig_task_ignored(t, sig, force))
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		return 0;

	/*
	 * Tracers may want to know about even ignored signals.
	 */
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	return !t->ptrace;
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}

/*
 * Re-calculate pending state from the set of locally pending
 * signals, globally pending signals, and blocked signals.
 */
static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
{
	unsigned long ready;
	long i;

	switch (_NSIG_WORDS) {
	default:
		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
			ready |= signal->sig[i] &~ blocked->sig[i];
		break;

	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
		ready |= signal->sig[2] &~ blocked->sig[2];
		ready |= signal->sig[1] &~ blocked->sig[1];
		ready |= signal->sig[0] &~ blocked->sig[0];
		break;

	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
		ready |= signal->sig[0] &~ blocked->sig[0];
		break;

	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
	}
	return ready !=	0;
}

#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))

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static int recalc_sigpending_tsk(struct task_struct *t)
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{
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	if ((t->jobctl & JOBCTL_PENDING_MASK) ||
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	    PENDING(&t->pending, &t->blocked) ||
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	    PENDING(&t->signal->shared_pending, &t->blocked)) {
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		set_tsk_thread_flag(t, TIF_SIGPENDING);
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		return 1;
	}
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	/*
	 * We must never clear the flag in another thread, or in current
	 * when it's possible the current syscall is returning -ERESTART*.
	 * So we don't clear it here, and only callers who know they should do.
	 */
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	return 0;
}

/*
 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
 * This is superfluous when called on current, the wakeup is a harmless no-op.
 */
void recalc_sigpending_and_wake(struct task_struct *t)
{
	if (recalc_sigpending_tsk(t))
		signal_wake_up(t, 0);
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}

void recalc_sigpending(void)
{
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	if (!recalc_sigpending_tsk(current) && !freezing(current))
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		clear_thread_flag(TIF_SIGPENDING);

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}

/* Given the mask, find the first available signal that should be serviced. */

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#define SYNCHRONOUS_MASK \
	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
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	 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
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int next_signal(struct sigpending *pending, sigset_t *mask)
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{
	unsigned long i, *s, *m, x;
	int sig = 0;
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	s = pending->signal.sig;
	m = mask->sig;
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	/*
	 * Handle the first word specially: it contains the
	 * synchronous signals that need to be dequeued first.
	 */
	x = *s &~ *m;
	if (x) {
		if (x & SYNCHRONOUS_MASK)
			x &= SYNCHRONOUS_MASK;
		sig = ffz(~x) + 1;
		return sig;
	}

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	switch (_NSIG_WORDS) {
	default:
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		for (i = 1; i < _NSIG_WORDS; ++i) {
			x = *++s &~ *++m;
			if (!x)
				continue;
			sig = ffz(~x) + i*_NSIG_BPW + 1;
			break;
		}
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		break;

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	case 2:
		x = s[1] &~ m[1];
		if (!x)
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			break;
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		sig = ffz(~x) + _NSIG_BPW + 1;
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		break;

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	case 1:
		/* Nothing to do */
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		break;
	}
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	return sig;
}

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static inline void print_dropped_signal(int sig)
{
	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);

	if (!print_fatal_signals)
		return;

	if (!__ratelimit(&ratelimit_state))
		return;

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	pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
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				current->comm, current->pid, sig);
}

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/**
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 * task_set_jobctl_pending - set jobctl pending bits
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 * @task: target task
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 * @mask: pending bits to set
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 *
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 * Clear @mask from @task->jobctl.  @mask must be subset of
 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
 * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
 * cleared.  If @task is already being killed or exiting, this function
 * becomes noop.
 *
 * CONTEXT:
 * Must be called with @task->sighand->siglock held.
 *
 * RETURNS:
 * %true if @mask is set, %false if made noop because @task was dying.
 */
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bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask)
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{
	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));

	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
		return false;

	if (mask & JOBCTL_STOP_SIGMASK)
		task->jobctl &= ~JOBCTL_STOP_SIGMASK;

	task->jobctl |= mask;
	return true;
}

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/**
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 * task_clear_jobctl_trapping - clear jobctl trapping bit
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 * @task: target task
 *
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 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
 * Clear it and wake up the ptracer.  Note that we don't need any further
 * locking.  @task->siglock guarantees that @task->parent points to the
 * ptracer.
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 *
 * CONTEXT:
 * Must be called with @task->sighand->siglock held.
 */
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void task_clear_jobctl_trapping(struct task_struct *task)
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{
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	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
		task->jobctl &= ~JOBCTL_TRAPPING;
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		smp_mb();	/* advised by wake_up_bit() */
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		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
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	}
}

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/**
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 * task_clear_jobctl_pending - clear jobctl pending bits
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 * @task: target task
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 * @mask: pending bits to clear
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 *
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 * Clear @mask from @task->jobctl.  @mask must be subset of
 * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
 * STOP bits are cleared together.
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 *
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 * If clearing of @mask leaves no stop or trap pending, this function calls
 * task_clear_jobctl_trapping().
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 *
 * CONTEXT:
 * Must be called with @task->sighand->siglock held.
 */
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void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask)
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{
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	BUG_ON(mask & ~JOBCTL_PENDING_MASK);

	if (mask & JOBCTL_STOP_PENDING)
		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;

	task->jobctl &= ~mask;
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	if (!(task->jobctl & JOBCTL_PENDING_MASK))
		task_clear_jobctl_trapping(task);
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}

/**
 * task_participate_group_stop - participate in a group stop
 * @task: task participating in a group stop
 *
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 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
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 * Group stop states are cleared and the group stop count is consumed if
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 * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
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 * stop, the appropriate %SIGNAL_* flags are set.
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 *
 * CONTEXT:
 * Must be called with @task->sighand->siglock held.
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 *
 * RETURNS:
 * %true if group stop completion should be notified to the parent, %false
 * otherwise.
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 */
static bool task_participate_group_stop(struct task_struct *task)
{
	struct signal_struct *sig = task->signal;
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	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
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	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
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	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
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	if (!consume)
		return false;

	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
		sig->group_stop_count--;

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	/*
	 * Tell the caller to notify completion iff we are entering into a
	 * fresh group stop.  Read comment in do_signal_stop() for details.
	 */
	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
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		signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED);
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		return true;
	}
	return false;
}

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/*
 * allocate a new signal queue record
 * - this may be called without locks if and only if t == current, otherwise an
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 *   appropriate lock must be held to stop the target task from exiting
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 */
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static struct sigqueue *
__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
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{
	struct sigqueue *q = NULL;
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	struct user_struct *user;
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	/*
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	 * Protect access to @t credentials. This can go away when all
	 * callers hold rcu read lock.
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	 */
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	rcu_read_lock();
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	user = get_uid(__task_cred(t)->user);
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	atomic_inc(&user->sigpending);
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	rcu_read_unlock();
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	if (override_rlimit ||
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	    atomic_read(&user->sigpending) <=
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			task_rlimit(t, RLIMIT_SIGPENDING)) {
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		q = kmem_cache_alloc(sigqueue_cachep, flags);
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	} else {
		print_dropped_signal(sig);
	}

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	if (unlikely(q == NULL)) {
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		atomic_dec(&user->sigpending);
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		free_uid(user);
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	} else {
		INIT_LIST_HEAD(&q->list);
		q->flags = 0;
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		q->user = user;
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	}
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	return q;
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}

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static void __sigqueue_free(struct sigqueue *q)
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{
	if (q->flags & SIGQUEUE_PREALLOC)
		return;
	atomic_dec(&q->user->sigpending);
	free_uid(q->user);
	kmem_cache_free(sigqueue_cachep, q);
}

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void flush_sigqueue(struct sigpending *queue)
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{
	struct sigqueue *q;

	sigemptyset(&queue->signal);
	while (!list_empty(&queue->list)) {
		q = list_entry(queue->list.next, struct sigqueue , list);
		list_del_init(&q->list);
		__sigqueue_free(q);
	}
}

/*
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 * Flush all pending signals for this kthread.
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 */
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void flush_signals(struct task_struct *t)
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{
	unsigned long flags;

	spin_lock_irqsave(&t->sighand->siglock, flags);
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	clear_tsk_thread_flag(t, TIF_SIGPENDING);
	flush_sigqueue(&t->pending);
	flush_sigqueue(&t->signal->shared_pending);
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	spin_unlock_irqrestore(&t->sighand->siglock, flags);
}

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#ifdef CONFIG_POSIX_TIMERS
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static void __flush_itimer_signals(struct sigpending *pending)
{
	sigset_t signal, retain;
	struct sigqueue *q, *n;

	signal = pending->signal;
	sigemptyset(&retain);

	list_for_each_entry_safe(q, n, &pending->list, list) {
		int sig = q->info.si_signo;

		if (likely(q->info.si_code != SI_TIMER)) {
			sigaddset(&retain, sig);
		} else {
			sigdelset(&signal, sig);
			list_del_init(&q->list);
			__sigqueue_free(q);
		}
	}

	sigorsets(&pending->signal, &signal, &retain);
}

void flush_itimer_signals(void)
{
	struct task_struct *tsk = current;
	unsigned long flags;

	spin_lock_irqsave(&tsk->sighand->siglock, flags);
	__flush_itimer_signals(&tsk->pending);
	__flush_itimer_signals(&tsk->signal->shared_pending);
	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
}
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#endif
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void ignore_signals(struct task_struct *t)
{
	int i;

	for (i = 0; i < _NSIG; ++i)
		t->sighand->action[i].sa.sa_handler = SIG_IGN;

	flush_signals(t);
}

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/*
 * Flush all handlers for a task.
 */

void
flush_signal_handlers(struct task_struct *t, int force_default)
{
	int i;
	struct k_sigaction *ka = &t->sighand->action[0];
	for (i = _NSIG ; i != 0 ; i--) {
		if (force_default || ka->sa.sa_handler != SIG_IGN)
			ka->sa.sa_handler = SIG_DFL;
		ka->sa.sa_flags = 0;
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#ifdef __ARCH_HAS_SA_RESTORER
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		ka->sa.sa_restorer = NULL;
#endif
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		sigemptyset(&ka->sa.sa_mask);
		ka++;
	}
}

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int unhandled_signal(struct task_struct *tsk, int sig)
{
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	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
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	if (is_global_init(tsk))
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		return 1;
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	if (handler != SIG_IGN && handler != SIG_DFL)
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		return 0;
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	/* if ptraced, let the tracer determine */
	return !tsk->ptrace;
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}

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static void collect_signal(int sig, struct sigpending *list, siginfo_t *info,
			   bool *resched_timer)
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{
	struct sigqueue *q, *first = NULL;

	/*
	 * Collect the siginfo appropriate to this signal.  Check if
	 * there is another siginfo for the same signal.
	*/
	list_for_each_entry(q, &list->list, list) {
		if (q->info.si_signo == sig) {
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			if (first)
				goto still_pending;
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			first = q;
		}
	}
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	sigdelset(&list->signal, sig);

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	if (first) {
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still_pending:
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		list_del_init(&first->list);
		copy_siginfo(info, &first->info);
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		*resched_timer =
			(first->flags & SIGQUEUE_PREALLOC) &&
			(info->si_code == SI_TIMER) &&
			(info->si_sys_private);

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		__sigqueue_free(first);
	} else {
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		/*
		 * Ok, it wasn't in the queue.  This must be
		 * a fast-pathed signal or we must have been
		 * out of queue space.  So zero out the info.
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		 */
		info->si_signo = sig;
		info->si_errno = 0;
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		info->si_code = SI_USER;
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		info->si_pid = 0;
		info->si_uid = 0;
	}
}

static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
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			siginfo_t *info, bool *resched_timer)
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{
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	int sig = next_signal(pending, mask);
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	if (sig)
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		collect_signal(sig, pending, info, resched_timer);
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	return sig;
}

/*
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 * Dequeue a signal and return the element to the caller, which is
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 * expected to free it.
 *
 * All callers have to hold the siglock.
 */
int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
{
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	bool resched_timer = false;
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	int signr;
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	/* We only dequeue private signals from ourselves, we don't let
	 * signalfd steal them
	 */
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	signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
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	if (!signr) {
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		signr = __dequeue_signal(&tsk->signal->shared_pending,
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					 mask, info, &resched_timer);
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#ifdef CONFIG_POSIX_TIMERS
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		/*
		 * itimer signal ?
		 *
		 * itimers are process shared and we restart periodic
		 * itimers in the signal delivery path to prevent DoS
		 * attacks in the high resolution timer case. This is
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		 * compliant with the old way of self-restarting
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		 * itimers, as the SIGALRM is a legacy signal and only
		 * queued once. Changing the restart behaviour to
		 * restart the timer in the signal dequeue path is
		 * reducing the timer noise on heavy loaded !highres
		 * systems too.
		 */
		if (unlikely(signr == SIGALRM)) {
			struct hrtimer *tmr = &tsk->signal->real_timer;

			if (!hrtimer_is_queued(tmr) &&
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			    tsk->signal->it_real_incr != 0) {
605 606 607 608 609
				hrtimer_forward(tmr, tmr->base->get_time(),
						tsk->signal->it_real_incr);
				hrtimer_restart(tmr);
			}
		}
610
#endif
611
	}
612

D
Davide Libenzi 已提交
613
	recalc_sigpending();
614 615 616 617
	if (!signr)
		return 0;

	if (unlikely(sig_kernel_stop(signr))) {
618 619 620 621 622 623 624 625 626 627 628 629
		/*
		 * Set a marker that we have dequeued a stop signal.  Our
		 * caller might release the siglock and then the pending
		 * stop signal it is about to process is no longer in the
		 * pending bitmasks, but must still be cleared by a SIGCONT
		 * (and overruled by a SIGKILL).  So those cases clear this
		 * shared flag after we've set it.  Note that this flag may
		 * remain set after the signal we return is ignored or
		 * handled.  That doesn't matter because its only purpose
		 * is to alert stop-signal processing code when another
		 * processor has come along and cleared the flag.
		 */
630
		current->jobctl |= JOBCTL_STOP_DEQUEUED;
631
	}
632
#ifdef CONFIG_POSIX_TIMERS
633
	if (resched_timer) {
L
Linus Torvalds 已提交
634 635 636 637 638 639 640
		/*
		 * Release the siglock to ensure proper locking order
		 * of timer locks outside of siglocks.  Note, we leave
		 * irqs disabled here, since the posix-timers code is
		 * about to disable them again anyway.
		 */
		spin_unlock(&tsk->sighand->siglock);
641
		posixtimer_rearm(info);
L
Linus Torvalds 已提交
642 643
		spin_lock(&tsk->sighand->siglock);
	}
644
#endif
L
Linus Torvalds 已提交
645 646 647 648 649 650 651 652 653 654 655 656 657 658
	return signr;
}

/*
 * Tell a process that it has a new active signal..
 *
 * NOTE! we rely on the previous spin_lock to
 * lock interrupts for us! We can only be called with
 * "siglock" held, and the local interrupt must
 * have been disabled when that got acquired!
 *
 * No need to set need_resched since signal event passing
 * goes through ->blocked
 */
659
void signal_wake_up_state(struct task_struct *t, unsigned int state)
L
Linus Torvalds 已提交
660 661 662
{
	set_tsk_thread_flag(t, TIF_SIGPENDING);
	/*
663
	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
M
Matthew Wilcox 已提交
664
	 * case. We don't check t->state here because there is a race with it
L
Linus Torvalds 已提交
665 666 667 668
	 * executing another processor and just now entering stopped state.
	 * By using wake_up_state, we ensure the process will wake up and
	 * handle its death signal.
	 */
669
	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
L
Linus Torvalds 已提交
670 671 672
		kick_process(t);
}

673 674 675 676 677 678
/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 */
679
static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
680 681 682 683 684 685 686 687
{
	struct sigqueue *q, *n;
	sigset_t m;

	sigandsets(&m, mask, &s->signal);
	if (sigisemptyset(&m))
		return 0;

688
	sigandnsets(&s->signal, &s->signal, mask);
689 690 691 692 693 694 695 696
	list_for_each_entry_safe(q, n, &s->list, list) {
		if (sigismember(mask, q->info.si_signo)) {
			list_del_init(&q->list);
			__sigqueue_free(q);
		}
	}
	return 1;
}
L
Linus Torvalds 已提交
697

698 699 700 701 702 703 704 705 706 707 708
static inline int is_si_special(const struct siginfo *info)
{
	return info <= SEND_SIG_FORCED;
}

static inline bool si_fromuser(const struct siginfo *info)
{
	return info == SEND_SIG_NOINFO ||
		(!is_si_special(info) && SI_FROMUSER(info));
}

709 710 711 712 713 714 715 716
/*
 * called with RCU read lock from check_kill_permission()
 */
static int kill_ok_by_cred(struct task_struct *t)
{
	const struct cred *cred = current_cred();
	const struct cred *tcred = __task_cred(t);

717 718 719 720
	if (uid_eq(cred->euid, tcred->suid) ||
	    uid_eq(cred->euid, tcred->uid)  ||
	    uid_eq(cred->uid,  tcred->suid) ||
	    uid_eq(cred->uid,  tcred->uid))
721 722
		return 1;

723
	if (ns_capable(tcred->user_ns, CAP_KILL))
724 725 726 727 728
		return 1;

	return 0;
}

L
Linus Torvalds 已提交
729 730
/*
 * Bad permissions for sending the signal
731
 * - the caller must hold the RCU read lock
L
Linus Torvalds 已提交
732 733 734 735
 */
static int check_kill_permission(int sig, struct siginfo *info,
				 struct task_struct *t)
{
736
	struct pid *sid;
737 738
	int error;

739
	if (!valid_signal(sig))
740 741
		return -EINVAL;

742
	if (!si_fromuser(info))
743
		return 0;
A
Amy Griffis 已提交
744

745 746
	error = audit_signal_info(sig, t); /* Let audit system see the signal */
	if (error)
L
Linus Torvalds 已提交
747
		return error;
748

749
	if (!same_thread_group(current, t) &&
750
	    !kill_ok_by_cred(t)) {
751 752 753 754 755 756 757 758 759 760 761 762 763
		switch (sig) {
		case SIGCONT:
			sid = task_session(t);
			/*
			 * We don't return the error if sid == NULL. The
			 * task was unhashed, the caller must notice this.
			 */
			if (!sid || sid == task_session(current))
				break;
		default:
			return -EPERM;
		}
	}
764

A
Amy Griffis 已提交
765
	return security_task_kill(t, info, sig, 0);
L
Linus Torvalds 已提交
766 767
}

768 769 770 771 772 773 774 775
/**
 * ptrace_trap_notify - schedule trap to notify ptracer
 * @t: tracee wanting to notify tracer
 *
 * This function schedules sticky ptrace trap which is cleared on the next
 * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
 * ptracer.
 *
T
Tejun Heo 已提交
776 777 778 779 780
 * If @t is running, STOP trap will be taken.  If trapped for STOP and
 * ptracer is listening for events, tracee is woken up so that it can
 * re-trap for the new event.  If trapped otherwise, STOP trap will be
 * eventually taken without returning to userland after the existing traps
 * are finished by PTRACE_CONT.
781 782 783 784 785 786 787 788 789 790
 *
 * CONTEXT:
 * Must be called with @task->sighand->siglock held.
 */
static void ptrace_trap_notify(struct task_struct *t)
{
	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
	assert_spin_locked(&t->sighand->siglock);

	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
791
	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
792 793
}

L
Linus Torvalds 已提交
794
/*
795 796
 * Handle magic process-wide effects of stop/continue signals. Unlike
 * the signal actions, these happen immediately at signal-generation
L
Linus Torvalds 已提交
797 798
 * time regardless of blocking, ignoring, or handling.  This does the
 * actual continuing for SIGCONT, but not the actual stopping for stop
799 800 801 802
 * signals. The process stop is done as a signal action for SIG_DFL.
 *
 * Returns true if the signal should be actually delivered, otherwise
 * it should be dropped.
L
Linus Torvalds 已提交
803
 */
804
static bool prepare_signal(int sig, struct task_struct *p, bool force)
L
Linus Torvalds 已提交
805
{
806
	struct signal_struct *signal = p->signal;
L
Linus Torvalds 已提交
807
	struct task_struct *t;
808
	sigset_t flush;
L
Linus Torvalds 已提交
809

810
	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
811
		if (!(signal->flags & SIGNAL_GROUP_EXIT))
812
			return sig == SIGKILL;
L
Linus Torvalds 已提交
813
		/*
814
		 * The process is in the middle of dying, nothing to do.
L
Linus Torvalds 已提交
815
		 */
816
	} else if (sig_kernel_stop(sig)) {
L
Linus Torvalds 已提交
817 818 819
		/*
		 * This is a stop signal.  Remove SIGCONT from all queues.
		 */
820
		siginitset(&flush, sigmask(SIGCONT));
821
		flush_sigqueue_mask(&flush, &signal->shared_pending);
822
		for_each_thread(p, t)
823
			flush_sigqueue_mask(&flush, &t->pending);
L
Linus Torvalds 已提交
824
	} else if (sig == SIGCONT) {
825
		unsigned int why;
L
Linus Torvalds 已提交
826
		/*
827
		 * Remove all stop signals from all queues, wake all threads.
L
Linus Torvalds 已提交
828
		 */
829
		siginitset(&flush, SIG_KERNEL_STOP_MASK);
830
		flush_sigqueue_mask(&flush, &signal->shared_pending);
831
		for_each_thread(p, t) {
832
			flush_sigqueue_mask(&flush, &t->pending);
833
			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
834 835 836 837
			if (likely(!(t->ptrace & PT_SEIZED)))
				wake_up_state(t, __TASK_STOPPED);
			else
				ptrace_trap_notify(t);
838
		}
L
Linus Torvalds 已提交
839

840 841 842 843 844 845 846 847 848
		/*
		 * Notify the parent with CLD_CONTINUED if we were stopped.
		 *
		 * If we were in the middle of a group stop, we pretend it
		 * was already finished, and then continued. Since SIGCHLD
		 * doesn't queue we report only CLD_STOPPED, as if the next
		 * CLD_CONTINUED was dropped.
		 */
		why = 0;
849
		if (signal->flags & SIGNAL_STOP_STOPPED)
850
			why |= SIGNAL_CLD_CONTINUED;
851
		else if (signal->group_stop_count)
852 853 854
			why |= SIGNAL_CLD_STOPPED;

		if (why) {
855
			/*
856
			 * The first thread which returns from do_signal_stop()
857 858 859
			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
			 * notify its parent. See get_signal_to_deliver().
			 */
860
			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
861 862
			signal->group_stop_count = 0;
			signal->group_exit_code = 0;
L
Linus Torvalds 已提交
863 864
		}
	}
865

866
	return !sig_ignored(p, sig, force);
L
Linus Torvalds 已提交
867 868
}

869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889
/*
 * Test if P wants to take SIG.  After we've checked all threads with this,
 * it's equivalent to finding no threads not blocking SIG.  Any threads not
 * blocking SIG were ruled out because they are not running and already
 * have pending signals.  Such threads will dequeue from the shared queue
 * as soon as they're available, so putting the signal on the shared queue
 * will be equivalent to sending it to one such thread.
 */
static inline int wants_signal(int sig, struct task_struct *p)
{
	if (sigismember(&p->blocked, sig))
		return 0;
	if (p->flags & PF_EXITING)
		return 0;
	if (sig == SIGKILL)
		return 1;
	if (task_is_stopped_or_traced(p))
		return 0;
	return task_curr(p) || !signal_pending(p);
}

890
static void complete_signal(int sig, struct task_struct *p, int group)
891 892 893 894 895 896 897 898 899 900 901 902
{
	struct signal_struct *signal = p->signal;
	struct task_struct *t;

	/*
	 * Now find a thread we can wake up to take the signal off the queue.
	 *
	 * If the main thread wants the signal, it gets first crack.
	 * Probably the least surprising to the average bear.
	 */
	if (wants_signal(sig, p))
		t = p;
903
	else if (!group || thread_group_empty(p))
904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930
		/*
		 * There is just one thread and it does not need to be woken.
		 * It will dequeue unblocked signals before it runs again.
		 */
		return;
	else {
		/*
		 * Otherwise try to find a suitable thread.
		 */
		t = signal->curr_target;
		while (!wants_signal(sig, t)) {
			t = next_thread(t);
			if (t == signal->curr_target)
				/*
				 * No thread needs to be woken.
				 * Any eligible threads will see
				 * the signal in the queue soon.
				 */
				return;
		}
		signal->curr_target = t;
	}

	/*
	 * Found a killable thread.  If the signal will be fatal,
	 * then start taking the whole group down immediately.
	 */
931 932
	if (sig_fatal(p, sig) &&
	    !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
933
	    !sigismember(&t->real_blocked, sig) &&
T
Tejun Heo 已提交
934
	    (sig == SIGKILL || !t->ptrace)) {
935 936 937 938 939 940 941 942 943 944 945 946 947 948 949
		/*
		 * This signal will be fatal to the whole group.
		 */
		if (!sig_kernel_coredump(sig)) {
			/*
			 * Start a group exit and wake everybody up.
			 * This way we don't have other threads
			 * running and doing things after a slower
			 * thread has the fatal signal pending.
			 */
			signal->flags = SIGNAL_GROUP_EXIT;
			signal->group_exit_code = sig;
			signal->group_stop_count = 0;
			t = p;
			do {
950
				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
951 952 953 954 955 956 957 958 959 960 961 962 963 964 965
				sigaddset(&t->pending.signal, SIGKILL);
				signal_wake_up(t, 1);
			} while_each_thread(p, t);
			return;
		}
	}

	/*
	 * The signal is already in the shared-pending queue.
	 * Tell the chosen thread to wake up and dequeue it.
	 */
	signal_wake_up(t, sig == SIGKILL);
	return;
}

966 967 968 969 970
static inline int legacy_queue(struct sigpending *signals, int sig)
{
	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
}

971 972 973 974 975 976 977 978 979
#ifdef CONFIG_USER_NS
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
{
	if (current_user_ns() == task_cred_xxx(t, user_ns))
		return;

	if (SI_FROMKERNEL(info))
		return;

980 981 982 983
	rcu_read_lock();
	info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
					make_kuid(current_user_ns(), info->si_uid));
	rcu_read_unlock();
984 985 986 987 988 989 990 991
}
#else
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
{
	return;
}
#endif

992 993
static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
			int group, int from_ancestor_ns)
L
Linus Torvalds 已提交
994
{
995
	struct sigpending *pending;
996
	struct sigqueue *q;
997
	int override_rlimit;
998
	int ret = 0, result;
999

1000
	assert_spin_locked(&t->sighand->siglock);
1001

1002
	result = TRACE_SIGNAL_IGNORED;
1003 1004
	if (!prepare_signal(sig, t,
			from_ancestor_ns || (info == SEND_SIG_FORCED)))
1005
		goto ret;
1006 1007

	pending = group ? &t->signal->shared_pending : &t->pending;
1008 1009 1010 1011 1012
	/*
	 * Short-circuit ignored signals and support queuing
	 * exactly one non-rt signal, so that we can get more
	 * detailed information about the cause of the signal.
	 */
1013
	result = TRACE_SIGNAL_ALREADY_PENDING;
1014
	if (legacy_queue(pending, sig))
1015 1016 1017
		goto ret;

	result = TRACE_SIGNAL_DELIVERED;
L
Linus Torvalds 已提交
1018 1019 1020 1021
	/*
	 * fast-pathed signals for kernel-internal things like SIGSTOP
	 * or SIGKILL.
	 */
1022
	if (info == SEND_SIG_FORCED)
L
Linus Torvalds 已提交
1023 1024
		goto out_set;

1025 1026 1027 1028 1029 1030 1031 1032 1033
	/*
	 * Real-time signals must be queued if sent by sigqueue, or
	 * some other real-time mechanism.  It is implementation
	 * defined whether kill() does so.  We attempt to do so, on
	 * the principle of least surprise, but since kill is not
	 * allowed to fail with EAGAIN when low on memory we just
	 * make sure at least one signal gets delivered and don't
	 * pass on the info struct.
	 */
1034 1035 1036 1037 1038
	if (sig < SIGRTMIN)
		override_rlimit = (is_si_special(info) || info->si_code >= 0);
	else
		override_rlimit = 0;

1039
	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1040
		override_rlimit);
L
Linus Torvalds 已提交
1041
	if (q) {
1042
		list_add_tail(&q->list, &pending->list);
L
Linus Torvalds 已提交
1043
		switch ((unsigned long) info) {
1044
		case (unsigned long) SEND_SIG_NOINFO:
L
Linus Torvalds 已提交
1045 1046 1047
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_USER;
1048
			q->info.si_pid = task_tgid_nr_ns(current,
1049
							task_active_pid_ns(t));
1050
			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1051
			break;
1052
		case (unsigned long) SEND_SIG_PRIV:
L
Linus Torvalds 已提交
1053 1054 1055 1056 1057 1058 1059 1060
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_KERNEL;
			q->info.si_pid = 0;
			q->info.si_uid = 0;
			break;
		default:
			copy_siginfo(&q->info, info);
1061 1062
			if (from_ancestor_ns)
				q->info.si_pid = 0;
L
Linus Torvalds 已提交
1063 1064
			break;
		}
1065 1066 1067

		userns_fixup_signal_uid(&q->info, t);

1068
	} else if (!is_si_special(info)) {
1069 1070 1071 1072 1073 1074
		if (sig >= SIGRTMIN && info->si_code != SI_USER) {
			/*
			 * Queue overflow, abort.  We may abort if the
			 * signal was rt and sent by user using something
			 * other than kill().
			 */
1075 1076 1077
			result = TRACE_SIGNAL_OVERFLOW_FAIL;
			ret = -EAGAIN;
			goto ret;
1078 1079 1080 1081 1082
		} else {
			/*
			 * This is a silent loss of information.  We still
			 * send the signal, but the *info bits are lost.
			 */
1083
			result = TRACE_SIGNAL_LOSE_INFO;
1084
		}
L
Linus Torvalds 已提交
1085 1086 1087
	}

out_set:
1088
	signalfd_notify(t, sig);
1089
	sigaddset(&pending->signal, sig);
1090
	complete_signal(sig, t, group);
1091 1092 1093
ret:
	trace_signal_generate(sig, info, t, group, result);
	return ret;
L
Linus Torvalds 已提交
1094 1095
}

1096 1097 1098
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
			int group)
{
1099 1100 1101
	int from_ancestor_ns = 0;

#ifdef CONFIG_PID_NS
1102 1103
	from_ancestor_ns = si_fromuser(info) &&
			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1104 1105 1106
#endif

	return __send_signal(sig, info, t, group, from_ancestor_ns);
1107 1108
}

1109
static void print_fatal_signal(int signr)
I
Ingo Molnar 已提交
1110
{
1111
	struct pt_regs *regs = signal_pt_regs();
1112
	pr_info("potentially unexpected fatal signal %d.\n", signr);
I
Ingo Molnar 已提交
1113

A
Al Viro 已提交
1114
#if defined(__i386__) && !defined(__arch_um__)
1115
	pr_info("code at %08lx: ", regs->ip);
I
Ingo Molnar 已提交
1116 1117 1118 1119 1120
	{
		int i;
		for (i = 0; i < 16; i++) {
			unsigned char insn;

1121 1122
			if (get_user(insn, (unsigned char *)(regs->ip + i)))
				break;
1123
			pr_cont("%02x ", insn);
I
Ingo Molnar 已提交
1124 1125
		}
	}
1126
	pr_cont("\n");
I
Ingo Molnar 已提交
1127
#endif
1128
	preempt_disable();
I
Ingo Molnar 已提交
1129
	show_regs(regs);
1130
	preempt_enable();
I
Ingo Molnar 已提交
1131 1132 1133 1134 1135 1136 1137 1138 1139 1140
}

static int __init setup_print_fatal_signals(char *str)
{
	get_option (&str, &print_fatal_signals);

	return 1;
}

__setup("print-fatal-signals=", setup_print_fatal_signals);
L
Linus Torvalds 已提交
1141

1142 1143 1144 1145 1146 1147
int
__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
	return send_signal(sig, info, p, 1);
}

L
Linus Torvalds 已提交
1148 1149 1150
static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
1151
	return send_signal(sig, info, t, 0);
L
Linus Torvalds 已提交
1152 1153
}

1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167
int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
			bool group)
{
	unsigned long flags;
	int ret = -ESRCH;

	if (lock_task_sighand(p, &flags)) {
		ret = send_signal(sig, info, p, group);
		unlock_task_sighand(p, &flags);
	}

	return ret;
}

L
Linus Torvalds 已提交
1168 1169 1170
/*
 * Force a signal that the process can't ignore: if necessary
 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1171 1172 1173 1174 1175
 *
 * Note: If we unblock the signal, we always reset it to SIG_DFL,
 * since we do not want to have a signal handler that was blocked
 * be invoked when user space had explicitly blocked it.
 *
1176 1177
 * We don't want to have recursive SIGSEGV's etc, for example,
 * that is why we also clear SIGNAL_UNKILLABLE.
L
Linus Torvalds 已提交
1178 1179 1180 1181 1182
 */
int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
	unsigned long int flags;
1183 1184
	int ret, blocked, ignored;
	struct k_sigaction *action;
L
Linus Torvalds 已提交
1185 1186

	spin_lock_irqsave(&t->sighand->siglock, flags);
1187 1188 1189 1190 1191 1192 1193
	action = &t->sighand->action[sig-1];
	ignored = action->sa.sa_handler == SIG_IGN;
	blocked = sigismember(&t->blocked, sig);
	if (blocked || ignored) {
		action->sa.sa_handler = SIG_DFL;
		if (blocked) {
			sigdelset(&t->blocked, sig);
R
Roland McGrath 已提交
1194
			recalc_sigpending_and_wake(t);
1195
		}
L
Linus Torvalds 已提交
1196
	}
1197 1198
	if (action->sa.sa_handler == SIG_DFL)
		t->signal->flags &= ~SIGNAL_UNKILLABLE;
L
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1199 1200 1201 1202 1203 1204 1205 1206 1207
	ret = specific_send_sig_info(sig, info, t);
	spin_unlock_irqrestore(&t->sighand->siglock, flags);

	return ret;
}

/*
 * Nuke all other threads in the group.
 */
1208
int zap_other_threads(struct task_struct *p)
L
Linus Torvalds 已提交
1209
{
1210 1211
	struct task_struct *t = p;
	int count = 0;
L
Linus Torvalds 已提交
1212 1213 1214

	p->signal->group_stop_count = 0;

1215
	while_each_thread(p, t) {
1216
		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1217 1218 1219
		count++;

		/* Don't bother with already dead threads */
L
Linus Torvalds 已提交
1220 1221 1222 1223 1224
		if (t->exit_state)
			continue;
		sigaddset(&t->pending.signal, SIGKILL);
		signal_wake_up(t, 1);
	}
1225 1226

	return count;
L
Linus Torvalds 已提交
1227 1228
}

1229 1230
struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
					   unsigned long *flags)
1231 1232 1233 1234
{
	struct sighand_struct *sighand;

	for (;;) {
1235 1236 1237 1238
		/*
		 * Disable interrupts early to avoid deadlocks.
		 * See rcu_read_unlock() comment header for details.
		 */
1239 1240
		local_irq_save(*flags);
		rcu_read_lock();
1241
		sighand = rcu_dereference(tsk->sighand);
1242 1243 1244
		if (unlikely(sighand == NULL)) {
			rcu_read_unlock();
			local_irq_restore(*flags);
1245
			break;
1246
		}
1247 1248
		/*
		 * This sighand can be already freed and even reused, but
1249
		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1250 1251 1252 1253 1254 1255 1256 1257
		 * initializes ->siglock: this slab can't go away, it has
		 * the same object type, ->siglock can't be reinitialized.
		 *
		 * We need to ensure that tsk->sighand is still the same
		 * after we take the lock, we can race with de_thread() or
		 * __exit_signal(). In the latter case the next iteration
		 * must see ->sighand == NULL.
		 */
1258 1259 1260
		spin_lock(&sighand->siglock);
		if (likely(sighand == tsk->sighand)) {
			rcu_read_unlock();
1261
			break;
1262 1263 1264 1265
		}
		spin_unlock(&sighand->siglock);
		rcu_read_unlock();
		local_irq_restore(*flags);
1266 1267 1268 1269 1270
	}

	return sighand;
}

1271 1272 1273
/*
 * send signal info to all the members of a group
 */
L
Linus Torvalds 已提交
1274 1275
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
1276 1277 1278 1279 1280
	int ret;

	rcu_read_lock();
	ret = check_kill_permission(sig, info, p);
	rcu_read_unlock();
1281

1282 1283
	if (!ret && sig)
		ret = do_send_sig_info(sig, info, p, true);
L
Linus Torvalds 已提交
1284 1285 1286 1287 1288

	return ret;
}

/*
1289
 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
L
Linus Torvalds 已提交
1290
 * control characters do (^C, ^Z etc)
1291
 * - the caller must hold at least a readlock on tasklist_lock
L
Linus Torvalds 已提交
1292
 */
1293
int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
L
Linus Torvalds 已提交
1294 1295 1296 1297 1298 1299
{
	struct task_struct *p = NULL;
	int retval, success;

	success = 0;
	retval = -ESRCH;
1300
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
L
Linus Torvalds 已提交
1301 1302 1303
		int err = group_send_sig_info(sig, info, p);
		success |= !err;
		retval = err;
1304
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
L
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1305 1306 1307
	return success ? 0 : retval;
}

1308
int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
L
Linus Torvalds 已提交
1309
{
1310
	int error = -ESRCH;
L
Linus Torvalds 已提交
1311 1312
	struct task_struct *p;

1313 1314 1315 1316 1317 1318 1319 1320
	for (;;) {
		rcu_read_lock();
		p = pid_task(pid, PIDTYPE_PID);
		if (p)
			error = group_send_sig_info(sig, info, p);
		rcu_read_unlock();
		if (likely(!p || error != -ESRCH))
			return error;
1321

1322 1323 1324 1325 1326 1327
		/*
		 * The task was unhashed in between, try again.  If it
		 * is dead, pid_task() will return NULL, if we race with
		 * de_thread() it will find the new leader.
		 */
	}
L
Linus Torvalds 已提交
1328 1329
}

1330
static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1331 1332 1333
{
	int error;
	rcu_read_lock();
1334
	error = kill_pid_info(sig, info, find_vpid(pid));
1335 1336 1337 1338
	rcu_read_unlock();
	return error;
}

1339 1340 1341 1342
static int kill_as_cred_perm(const struct cred *cred,
			     struct task_struct *target)
{
	const struct cred *pcred = __task_cred(target);
1343 1344
	if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
	    !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
1345 1346 1347 1348
		return 0;
	return 1;
}

1349
/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1350 1351
int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
			 const struct cred *cred, u32 secid)
1352 1353 1354
{
	int ret = -EINVAL;
	struct task_struct *p;
1355
	unsigned long flags;
1356 1357 1358 1359

	if (!valid_signal(sig))
		return ret;

1360
	rcu_read_lock();
1361
	p = pid_task(pid, PIDTYPE_PID);
1362 1363 1364 1365
	if (!p) {
		ret = -ESRCH;
		goto out_unlock;
	}
1366
	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1367 1368 1369
		ret = -EPERM;
		goto out_unlock;
	}
1370 1371 1372
	ret = security_task_kill(p, info, sig, secid);
	if (ret)
		goto out_unlock;
1373 1374 1375 1376 1377 1378 1379

	if (sig) {
		if (lock_task_sighand(p, &flags)) {
			ret = __send_signal(sig, info, p, 1, 0);
			unlock_task_sighand(p, &flags);
		} else
			ret = -ESRCH;
1380 1381
	}
out_unlock:
1382
	rcu_read_unlock();
1383 1384
	return ret;
}
1385
EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
L
Linus Torvalds 已提交
1386 1387 1388 1389 1390 1391 1392 1393

/*
 * kill_something_info() interprets pid in interesting ways just like kill(2).
 *
 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
 * is probably wrong.  Should make it like BSD or SYSV.
 */

1394
static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
L
Linus Torvalds 已提交
1395
{
1396
	int ret;
1397 1398 1399 1400 1401 1402 1403 1404

	if (pid > 0) {
		rcu_read_lock();
		ret = kill_pid_info(sig, info, find_vpid(pid));
		rcu_read_unlock();
		return ret;
	}

1405 1406 1407 1408
	/* -INT_MIN is undefined.  Exclude this case to avoid a UBSAN warning */
	if (pid == INT_MIN)
		return -ESRCH;

1409 1410 1411 1412 1413
	read_lock(&tasklist_lock);
	if (pid != -1) {
		ret = __kill_pgrp_info(sig, info,
				pid ? find_vpid(-pid) : task_pgrp(current));
	} else {
L
Linus Torvalds 已提交
1414 1415 1416 1417
		int retval = 0, count = 0;
		struct task_struct * p;

		for_each_process(p) {
1418 1419
			if (task_pid_vnr(p) > 1 &&
					!same_thread_group(p, current)) {
L
Linus Torvalds 已提交
1420 1421 1422 1423 1424 1425
				int err = group_send_sig_info(sig, info, p);
				++count;
				if (err != -EPERM)
					retval = err;
			}
		}
1426
		ret = count ? retval : -ESRCH;
L
Linus Torvalds 已提交
1427
	}
1428 1429
	read_unlock(&tasklist_lock);

1430
	return ret;
L
Linus Torvalds 已提交
1431 1432 1433 1434 1435 1436
}

/*
 * These are for backward compatibility with the rest of the kernel source.
 */

1437
int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
L
Linus Torvalds 已提交
1438 1439 1440 1441 1442
{
	/*
	 * Make sure legacy kernel users don't send in bad values
	 * (normal paths check this in check_kill_permission).
	 */
1443
	if (!valid_signal(sig))
L
Linus Torvalds 已提交
1444 1445
		return -EINVAL;

1446
	return do_send_sig_info(sig, info, p, false);
L
Linus Torvalds 已提交
1447 1448
}

1449 1450 1451
#define __si_special(priv) \
	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)

L
Linus Torvalds 已提交
1452 1453 1454
int
send_sig(int sig, struct task_struct *p, int priv)
{
1455
	return send_sig_info(sig, __si_special(priv), p);
L
Linus Torvalds 已提交
1456 1457 1458 1459 1460
}

void
force_sig(int sig, struct task_struct *p)
{
1461
	force_sig_info(sig, SEND_SIG_PRIV, p);
L
Linus Torvalds 已提交
1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482
}

/*
 * When things go south during signal handling, we
 * will force a SIGSEGV. And if the signal that caused
 * the problem was already a SIGSEGV, we'll want to
 * make sure we don't even try to deliver the signal..
 */
int
force_sigsegv(int sig, struct task_struct *p)
{
	if (sig == SIGSEGV) {
		unsigned long flags;
		spin_lock_irqsave(&p->sighand->siglock, flags);
		p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
		spin_unlock_irqrestore(&p->sighand->siglock, flags);
	}
	force_sig(SIGSEGV, p);
	return 0;
}

1483 1484
int kill_pgrp(struct pid *pid, int sig, int priv)
{
1485 1486 1487 1488 1489 1490 1491
	int ret;

	read_lock(&tasklist_lock);
	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
	read_unlock(&tasklist_lock);

	return ret;
1492 1493 1494 1495 1496 1497 1498 1499 1500
}
EXPORT_SYMBOL(kill_pgrp);

int kill_pid(struct pid *pid, int sig, int priv)
{
	return kill_pid_info(sig, __si_special(priv), pid);
}
EXPORT_SYMBOL(kill_pid);

L
Linus Torvalds 已提交
1501 1502 1503 1504
/*
 * These functions support sending signals using preallocated sigqueue
 * structures.  This is needed "because realtime applications cannot
 * afford to lose notifications of asynchronous events, like timer
1505
 * expirations or I/O completions".  In the case of POSIX Timers
L
Linus Torvalds 已提交
1506 1507 1508 1509 1510 1511
 * we allocate the sigqueue structure from the timer_create.  If this
 * allocation fails we are able to report the failure to the application
 * with an EAGAIN error.
 */
struct sigqueue *sigqueue_alloc(void)
{
1512
	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
L
Linus Torvalds 已提交
1513

1514
	if (q)
L
Linus Torvalds 已提交
1515
		q->flags |= SIGQUEUE_PREALLOC;
1516 1517

	return q;
L
Linus Torvalds 已提交
1518 1519 1520 1521 1522
}

void sigqueue_free(struct sigqueue *q)
{
	unsigned long flags;
1523 1524
	spinlock_t *lock = &current->sighand->siglock;

L
Linus Torvalds 已提交
1525 1526
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
	/*
1527 1528
	 * We must hold ->siglock while testing q->list
	 * to serialize with collect_signal() or with
1529
	 * __exit_signal()->flush_sigqueue().
L
Linus Torvalds 已提交
1530
	 */
1531
	spin_lock_irqsave(lock, flags);
1532 1533 1534 1535 1536
	q->flags &= ~SIGQUEUE_PREALLOC;
	/*
	 * If it is queued it will be freed when dequeued,
	 * like the "regular" sigqueue.
	 */
1537
	if (!list_empty(&q->list))
1538
		q = NULL;
1539 1540
	spin_unlock_irqrestore(lock, flags);

1541 1542
	if (q)
		__sigqueue_free(q);
L
Linus Torvalds 已提交
1543 1544
}

1545
int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1546
{
1547
	int sig = q->info.si_signo;
1548
	struct sigpending *pending;
1549
	unsigned long flags;
1550
	int ret, result;
1551

1552
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1553 1554 1555 1556 1557

	ret = -1;
	if (!likely(lock_task_sighand(t, &flags)))
		goto ret;

1558
	ret = 1; /* the signal is ignored */
1559
	result = TRACE_SIGNAL_IGNORED;
1560
	if (!prepare_signal(sig, t, false))
1561 1562 1563
		goto out;

	ret = 0;
1564 1565 1566 1567 1568 1569 1570
	if (unlikely(!list_empty(&q->list))) {
		/*
		 * If an SI_TIMER entry is already queue just increment
		 * the overrun count.
		 */
		BUG_ON(q->info.si_code != SI_TIMER);
		q->info.si_overrun++;
1571
		result = TRACE_SIGNAL_ALREADY_PENDING;
1572
		goto out;
1573
	}
1574
	q->info.si_overrun = 0;
1575 1576

	signalfd_notify(t, sig);
1577
	pending = group ? &t->signal->shared_pending : &t->pending;
1578 1579
	list_add_tail(&q->list, &pending->list);
	sigaddset(&pending->signal, sig);
1580
	complete_signal(sig, t, group);
1581
	result = TRACE_SIGNAL_DELIVERED;
1582
out:
1583
	trace_signal_generate(sig, &q->info, t, group, result);
1584 1585 1586
	unlock_task_sighand(t, &flags);
ret:
	return ret;
1587 1588
}

L
Linus Torvalds 已提交
1589 1590 1591
/*
 * Let a parent know about the death of a child.
 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
R
Roland McGrath 已提交
1592
 *
1593 1594
 * Returns true if our parent ignored us and so we've switched to
 * self-reaping.
L
Linus Torvalds 已提交
1595
 */
1596
bool do_notify_parent(struct task_struct *tsk, int sig)
L
Linus Torvalds 已提交
1597 1598 1599 1600
{
	struct siginfo info;
	unsigned long flags;
	struct sighand_struct *psig;
1601
	bool autoreap = false;
1602
	u64 utime, stime;
L
Linus Torvalds 已提交
1603 1604 1605 1606

	BUG_ON(sig == -1);

 	/* do_notify_parent_cldstop should have been called instead.  */
M
Matthew Wilcox 已提交
1607
 	BUG_ON(task_is_stopped_or_traced(tsk));
L
Linus Torvalds 已提交
1608

T
Tejun Heo 已提交
1609
	BUG_ON(!tsk->ptrace &&
L
Linus Torvalds 已提交
1610 1611
	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));

1612 1613 1614 1615 1616 1617 1618 1619 1620
	if (sig != SIGCHLD) {
		/*
		 * This is only possible if parent == real_parent.
		 * Check if it has changed security domain.
		 */
		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
			sig = SIGCHLD;
	}

L
Linus Torvalds 已提交
1621 1622
	info.si_signo = sig;
	info.si_errno = 0;
1623
	/*
1624 1625
	 * We are under tasklist_lock here so our parent is tied to
	 * us and cannot change.
1626
	 *
1627 1628
	 * task_active_pid_ns will always return the same pid namespace
	 * until a task passes through release_task.
1629 1630 1631 1632 1633 1634
	 *
	 * write_lock() currently calls preempt_disable() which is the
	 * same as rcu_read_lock(), but according to Oleg, this is not
	 * correct to rely on this
	 */
	rcu_read_lock();
1635
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1636 1637
	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
				       task_uid(tsk));
1638 1639
	rcu_read_unlock();

1640 1641 1642
	task_cputime(tsk, &utime, &stime);
	info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
	info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
L
Linus Torvalds 已提交
1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655

	info.si_status = tsk->exit_code & 0x7f;
	if (tsk->exit_code & 0x80)
		info.si_code = CLD_DUMPED;
	else if (tsk->exit_code & 0x7f)
		info.si_code = CLD_KILLED;
	else {
		info.si_code = CLD_EXITED;
		info.si_status = tsk->exit_code >> 8;
	}

	psig = tsk->parent->sighand;
	spin_lock_irqsave(&psig->siglock, flags);
T
Tejun Heo 已提交
1656
	if (!tsk->ptrace && sig == SIGCHLD &&
L
Linus Torvalds 已提交
1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673
	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
		/*
		 * We are exiting and our parent doesn't care.  POSIX.1
		 * defines special semantics for setting SIGCHLD to SIG_IGN
		 * or setting the SA_NOCLDWAIT flag: we should be reaped
		 * automatically and not left for our parent's wait4 call.
		 * Rather than having the parent do it as a magic kind of
		 * signal handler, we just set this to tell do_exit that we
		 * can be cleaned up without becoming a zombie.  Note that
		 * we still call __wake_up_parent in this case, because a
		 * blocked sys_wait4 might now return -ECHILD.
		 *
		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
		 * is implementation-defined: we do (if you don't want
		 * it, just use SIG_IGN instead).
		 */
1674
		autoreap = true;
L
Linus Torvalds 已提交
1675
		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1676
			sig = 0;
L
Linus Torvalds 已提交
1677
	}
1678
	if (valid_signal(sig) && sig)
L
Linus Torvalds 已提交
1679 1680 1681
		__group_send_sig_info(sig, &info, tsk->parent);
	__wake_up_parent(tsk, tsk->parent);
	spin_unlock_irqrestore(&psig->siglock, flags);
R
Roland McGrath 已提交
1682

1683
	return autoreap;
L
Linus Torvalds 已提交
1684 1685
}

1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700
/**
 * do_notify_parent_cldstop - notify parent of stopped/continued state change
 * @tsk: task reporting the state change
 * @for_ptracer: the notification is for ptracer
 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
 *
 * Notify @tsk's parent that the stopped/continued state has changed.  If
 * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
 * If %true, @tsk reports to @tsk->parent which should be the ptracer.
 *
 * CONTEXT:
 * Must be called with tasklist_lock at least read locked.
 */
static void do_notify_parent_cldstop(struct task_struct *tsk,
				     bool for_ptracer, int why)
L
Linus Torvalds 已提交
1701 1702 1703
{
	struct siginfo info;
	unsigned long flags;
1704
	struct task_struct *parent;
L
Linus Torvalds 已提交
1705
	struct sighand_struct *sighand;
1706
	u64 utime, stime;
L
Linus Torvalds 已提交
1707

1708
	if (for_ptracer) {
1709
		parent = tsk->parent;
1710
	} else {
1711 1712 1713 1714
		tsk = tsk->group_leader;
		parent = tsk->real_parent;
	}

L
Linus Torvalds 已提交
1715 1716
	info.si_signo = SIGCHLD;
	info.si_errno = 0;
1717
	/*
1718
	 * see comment in do_notify_parent() about the following 4 lines
1719 1720
	 */
	rcu_read_lock();
1721
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1722
	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1723 1724
	rcu_read_unlock();

1725 1726 1727
	task_cputime(tsk, &utime, &stime);
	info.si_utime = nsec_to_clock_t(utime);
	info.si_stime = nsec_to_clock_t(stime);
L
Linus Torvalds 已提交
1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755

 	info.si_code = why;
 	switch (why) {
 	case CLD_CONTINUED:
 		info.si_status = SIGCONT;
 		break;
 	case CLD_STOPPED:
 		info.si_status = tsk->signal->group_exit_code & 0x7f;
 		break;
 	case CLD_TRAPPED:
 		info.si_status = tsk->exit_code & 0x7f;
 		break;
 	default:
 		BUG();
 	}

	sighand = parent->sighand;
	spin_lock_irqsave(&sighand->siglock, flags);
	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
		__group_send_sig_info(SIGCHLD, &info, parent);
	/*
	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
	 */
	__wake_up_parent(tsk, parent);
	spin_unlock_irqrestore(&sighand->siglock, flags);
}

1756 1757
static inline int may_ptrace_stop(void)
{
T
Tejun Heo 已提交
1758
	if (!likely(current->ptrace))
1759 1760 1761 1762 1763 1764 1765
		return 0;
	/*
	 * Are we in the middle of do_coredump?
	 * If so and our tracer is also part of the coredump stopping
	 * is a deadlock situation, and pointless because our tracer
	 * is dead so don't allow us to stop.
	 * If SIGKILL was already sent before the caller unlocked
1766
	 * ->siglock we must see ->core_state != NULL. Otherwise it
1767
	 * is safe to enter schedule().
1768 1769 1770 1771
	 *
	 * This is almost outdated, a task with the pending SIGKILL can't
	 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
	 * after SIGKILL was already dequeued.
1772
	 */
1773
	if (unlikely(current->mm->core_state) &&
1774 1775 1776 1777 1778 1779
	    unlikely(current->mm == current->parent->mm))
		return 0;

	return 1;
}

R
Roland McGrath 已提交
1780
/*
1781
 * Return non-zero if there is a SIGKILL that should be waking us up.
R
Roland McGrath 已提交
1782 1783 1784 1785
 * Called with the siglock held.
 */
static int sigkill_pending(struct task_struct *tsk)
{
1786 1787
	return	sigismember(&tsk->pending.signal, SIGKILL) ||
		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
R
Roland McGrath 已提交
1788 1789
}

L
Linus Torvalds 已提交
1790 1791 1792 1793 1794 1795 1796 1797
/*
 * This must be called with current->sighand->siglock held.
 *
 * This should be the path for all ptrace stops.
 * We always set current->last_siginfo while stopped here.
 * That makes it a way to test a stopped process for
 * being ptrace-stopped vs being job-control-stopped.
 *
1798 1799
 * If we actually decide not to stop at all because the tracer
 * is gone, we keep current->exit_code unless clear_code.
L
Linus Torvalds 已提交
1800
 */
T
Tejun Heo 已提交
1801
static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1802 1803
	__releases(&current->sighand->siglock)
	__acquires(&current->sighand->siglock)
L
Linus Torvalds 已提交
1804
{
1805 1806
	bool gstop_done = false;

R
Roland McGrath 已提交
1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821
	if (arch_ptrace_stop_needed(exit_code, info)) {
		/*
		 * The arch code has something special to do before a
		 * ptrace stop.  This is allowed to block, e.g. for faults
		 * on user stack pages.  We can't keep the siglock while
		 * calling arch_ptrace_stop, so we must release it now.
		 * To preserve proper semantics, we must do this before
		 * any signal bookkeeping like checking group_stop_count.
		 * Meanwhile, a SIGKILL could come in before we retake the
		 * siglock.  That must prevent us from sleeping in TASK_TRACED.
		 * So after regaining the lock, we must check for SIGKILL.
		 */
		spin_unlock_irq(&current->sighand->siglock);
		arch_ptrace_stop(exit_code, info);
		spin_lock_irq(&current->sighand->siglock);
1822 1823
		if (sigkill_pending(current))
			return;
R
Roland McGrath 已提交
1824 1825
	}

L
Linus Torvalds 已提交
1826
	/*
1827 1828 1829 1830 1831
	 * We're committing to trapping.  TRACED should be visible before
	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
	 * Also, transition to TRACED and updates to ->jobctl should be
	 * atomic with respect to siglock and should be done after the arch
	 * hook as siglock is released and regrabbed across it.
L
Linus Torvalds 已提交
1832
	 */
1833
	set_current_state(TASK_TRACED);
L
Linus Torvalds 已提交
1834 1835 1836 1837

	current->last_siginfo = info;
	current->exit_code = exit_code;

1838
	/*
1839 1840
	 * If @why is CLD_STOPPED, we're trapping to participate in a group
	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1841 1842 1843
	 * across siglock relocks since INTERRUPT was scheduled, PENDING
	 * could be clear now.  We act as if SIGCONT is received after
	 * TASK_TRACED is entered - ignore it.
1844
	 */
1845
	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1846
		gstop_done = task_participate_group_stop(current);
1847

1848
	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1849
	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1850 1851
	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1852

1853
	/* entering a trap, clear TRAPPING */
1854
	task_clear_jobctl_trapping(current);
1855

L
Linus Torvalds 已提交
1856 1857
	spin_unlock_irq(&current->sighand->siglock);
	read_lock(&tasklist_lock);
1858
	if (may_ptrace_stop()) {
1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869
		/*
		 * Notify parents of the stop.
		 *
		 * While ptraced, there are two parents - the ptracer and
		 * the real_parent of the group_leader.  The ptracer should
		 * know about every stop while the real parent is only
		 * interested in the completion of group stop.  The states
		 * for the two don't interact with each other.  Notify
		 * separately unless they're gonna be duplicates.
		 */
		do_notify_parent_cldstop(current, true, why);
1870
		if (gstop_done && ptrace_reparented(current))
1871 1872
			do_notify_parent_cldstop(current, false, why);

M
Miklos Szeredi 已提交
1873 1874 1875 1876 1877 1878 1879
		/*
		 * Don't want to allow preemption here, because
		 * sys_ptrace() needs this task to be inactive.
		 *
		 * XXX: implement read_unlock_no_resched().
		 */
		preempt_disable();
L
Linus Torvalds 已提交
1880
		read_unlock(&tasklist_lock);
M
Miklos Szeredi 已提交
1881
		preempt_enable_no_resched();
1882
		freezable_schedule();
L
Linus Torvalds 已提交
1883 1884 1885
	} else {
		/*
		 * By the time we got the lock, our tracer went away.
1886
		 * Don't drop the lock yet, another tracer may come.
1887 1888 1889
		 *
		 * If @gstop_done, the ptracer went away between group stop
		 * completion and here.  During detach, it would have set
1890 1891 1892
		 * JOBCTL_STOP_PENDING on us and we'll re-enter
		 * TASK_STOPPED in do_signal_stop() on return, so notifying
		 * the real parent of the group stop completion is enough.
L
Linus Torvalds 已提交
1893
		 */
1894 1895 1896
		if (gstop_done)
			do_notify_parent_cldstop(current, false, why);

1897
		/* tasklist protects us from ptrace_freeze_traced() */
1898
		__set_current_state(TASK_RUNNING);
1899 1900
		if (clear_code)
			current->exit_code = 0;
1901
		read_unlock(&tasklist_lock);
L
Linus Torvalds 已提交
1902 1903 1904 1905 1906 1907 1908 1909 1910 1911
	}

	/*
	 * We are back.  Now reacquire the siglock before touching
	 * last_siginfo, so that we are sure to have synchronized with
	 * any signal-sending on another CPU that wants to examine it.
	 */
	spin_lock_irq(&current->sighand->siglock);
	current->last_siginfo = NULL;

T
Tejun Heo 已提交
1912 1913 1914
	/* LISTENING can be set only during STOP traps, clear it */
	current->jobctl &= ~JOBCTL_LISTENING;

L
Linus Torvalds 已提交
1915 1916 1917
	/*
	 * Queued signals ignored us while we were stopped for tracing.
	 * So check for any that we should take before resuming user mode.
1918
	 * This sets TIF_SIGPENDING, but never clears it.
L
Linus Torvalds 已提交
1919
	 */
1920
	recalc_sigpending_tsk(current);
L
Linus Torvalds 已提交
1921 1922
}

T
Tejun Heo 已提交
1923
static void ptrace_do_notify(int signr, int exit_code, int why)
L
Linus Torvalds 已提交
1924 1925 1926 1927
{
	siginfo_t info;

	memset(&info, 0, sizeof info);
T
Tejun Heo 已提交
1928
	info.si_signo = signr;
L
Linus Torvalds 已提交
1929
	info.si_code = exit_code;
1930
	info.si_pid = task_pid_vnr(current);
1931
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1932 1933

	/* Let the debugger run.  */
T
Tejun Heo 已提交
1934 1935 1936 1937 1938 1939
	ptrace_stop(exit_code, why, 1, &info);
}

void ptrace_notify(int exit_code)
{
	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1940 1941
	if (unlikely(current->task_works))
		task_work_run();
T
Tejun Heo 已提交
1942

L
Linus Torvalds 已提交
1943
	spin_lock_irq(&current->sighand->siglock);
T
Tejun Heo 已提交
1944
	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
L
Linus Torvalds 已提交
1945 1946 1947
	spin_unlock_irq(&current->sighand->siglock);
}

1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968
/**
 * do_signal_stop - handle group stop for SIGSTOP and other stop signals
 * @signr: signr causing group stop if initiating
 *
 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
 * and participate in it.  If already set, participate in the existing
 * group stop.  If participated in a group stop (and thus slept), %true is
 * returned with siglock released.
 *
 * If ptraced, this function doesn't handle stop itself.  Instead,
 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
 * untouched.  The caller must ensure that INTERRUPT trap handling takes
 * places afterwards.
 *
 * CONTEXT:
 * Must be called with @current->sighand->siglock held, which is released
 * on %true return.
 *
 * RETURNS:
 * %false if group stop is already cancelled or ptrace trap is scheduled.
 * %true if participated in group stop.
L
Linus Torvalds 已提交
1969
 */
1970 1971
static bool do_signal_stop(int signr)
	__releases(&current->sighand->siglock)
L
Linus Torvalds 已提交
1972 1973 1974
{
	struct signal_struct *sig = current->signal;

1975
	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1976
		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1977 1978
		struct task_struct *t;

1979 1980
		/* signr will be recorded in task->jobctl for retries */
		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1981

1982
		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1983
		    unlikely(signal_group_exit(sig)))
1984
			return false;
L
Linus Torvalds 已提交
1985
		/*
1986 1987 1988 1989 1990 1991 1992
		 * There is no group stop already in progress.  We must
		 * initiate one now.
		 *
		 * While ptraced, a task may be resumed while group stop is
		 * still in effect and then receive a stop signal and
		 * initiate another group stop.  This deviates from the
		 * usual behavior as two consecutive stop signals can't
1993 1994
		 * cause two group stops when !ptraced.  That is why we
		 * also check !task_is_stopped(t) below.
1995 1996 1997 1998 1999 2000 2001 2002
		 *
		 * The condition can be distinguished by testing whether
		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
		 * group_exit_code in such case.
		 *
		 * This is not necessary for SIGNAL_STOP_CONTINUED because
		 * an intervening stop signal is required to cause two
		 * continued events regardless of ptrace.
L
Linus Torvalds 已提交
2003
		 */
2004 2005
		if (!(sig->flags & SIGNAL_STOP_STOPPED))
			sig->group_exit_code = signr;
L
Linus Torvalds 已提交
2006

2007 2008 2009 2010
		sig->group_stop_count = 0;

		if (task_set_jobctl_pending(current, signr | gstop))
			sig->group_stop_count++;
L
Linus Torvalds 已提交
2011

2012 2013
		t = current;
		while_each_thread(current, t) {
L
Linus Torvalds 已提交
2014
			/*
2015 2016 2017
			 * Setting state to TASK_STOPPED for a group
			 * stop is always done with the siglock held,
			 * so this check has no races.
L
Linus Torvalds 已提交
2018
			 */
2019 2020
			if (!task_is_stopped(t) &&
			    task_set_jobctl_pending(t, signr | gstop)) {
2021
				sig->group_stop_count++;
2022 2023 2024 2025
				if (likely(!(t->ptrace & PT_SEIZED)))
					signal_wake_up(t, 0);
				else
					ptrace_trap_notify(t);
2026
			}
2027
		}
L
Linus Torvalds 已提交
2028
	}
2029

T
Tejun Heo 已提交
2030
	if (likely(!current->ptrace)) {
2031
		int notify = 0;
L
Linus Torvalds 已提交
2032

2033 2034 2035 2036 2037 2038 2039 2040
		/*
		 * If there are no other threads in the group, or if there
		 * is a group stop in progress and we are the last to stop,
		 * report to the parent.
		 */
		if (task_participate_group_stop(current))
			notify = CLD_STOPPED;

2041
		__set_current_state(TASK_STOPPED);
2042 2043
		spin_unlock_irq(&current->sighand->siglock);

2044 2045 2046 2047 2048 2049 2050 2051 2052
		/*
		 * Notify the parent of the group stop completion.  Because
		 * we're not holding either the siglock or tasklist_lock
		 * here, ptracer may attach inbetween; however, this is for
		 * group stop and should always be delivered to the real
		 * parent of the group leader.  The new ptracer will get
		 * its notification when this task transitions into
		 * TASK_TRACED.
		 */
2053 2054
		if (notify) {
			read_lock(&tasklist_lock);
2055
			do_notify_parent_cldstop(current, false, notify);
2056 2057 2058 2059
			read_unlock(&tasklist_lock);
		}

		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2060
		freezable_schedule();
2061
		return true;
2062
	} else {
2063 2064 2065 2066 2067 2068
		/*
		 * While ptraced, group stop is handled by STOP trap.
		 * Schedule it and let the caller deal with it.
		 */
		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
		return false;
2069
	}
2070
}
L
Linus Torvalds 已提交
2071

2072 2073 2074
/**
 * do_jobctl_trap - take care of ptrace jobctl traps
 *
T
Tejun Heo 已提交
2075 2076 2077 2078 2079 2080 2081
 * When PT_SEIZED, it's used for both group stop and explicit
 * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
 * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
 * the stop signal; otherwise, %SIGTRAP.
 *
 * When !PT_SEIZED, it's used only for group stop trap with stop signal
 * number as exit_code and no siginfo.
2082 2083 2084 2085 2086 2087 2088
 *
 * CONTEXT:
 * Must be called with @current->sighand->siglock held, which may be
 * released and re-acquired before returning with intervening sleep.
 */
static void do_jobctl_trap(void)
{
T
Tejun Heo 已提交
2089
	struct signal_struct *signal = current->signal;
2090
	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2091

T
Tejun Heo 已提交
2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102
	if (current->ptrace & PT_SEIZED) {
		if (!signal->group_stop_count &&
		    !(signal->flags & SIGNAL_STOP_STOPPED))
			signr = SIGTRAP;
		WARN_ON_ONCE(!signr);
		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
				 CLD_STOPPED);
	} else {
		WARN_ON_ONCE(!signr);
		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
		current->exit_code = 0;
2103
	}
L
Linus Torvalds 已提交
2104 2105
}

2106
static int ptrace_signal(int signr, siginfo_t *info)
R
Roland McGrath 已提交
2107
{
2108 2109 2110 2111 2112 2113 2114 2115 2116 2117
	/*
	 * We do not check sig_kernel_stop(signr) but set this marker
	 * unconditionally because we do not know whether debugger will
	 * change signr. This flag has no meaning unless we are going
	 * to stop after return from ptrace_stop(). In this case it will
	 * be checked in do_signal_stop(), we should only stop if it was
	 * not cleared by SIGCONT while we were sleeping. See also the
	 * comment in dequeue_signal().
	 */
	current->jobctl |= JOBCTL_STOP_DEQUEUED;
T
Tejun Heo 已提交
2118
	ptrace_stop(signr, CLD_TRAPPED, 0, info);
R
Roland McGrath 已提交
2119 2120 2121 2122 2123 2124 2125 2126

	/* We're back.  Did the debugger cancel the sig?  */
	signr = current->exit_code;
	if (signr == 0)
		return signr;

	current->exit_code = 0;

2127 2128 2129 2130 2131 2132
	/*
	 * Update the siginfo structure if the signal has
	 * changed.  If the debugger wanted something
	 * specific in the siginfo structure then it should
	 * have updated *info via PTRACE_SETSIGINFO.
	 */
R
Roland McGrath 已提交
2133 2134 2135 2136
	if (signr != info->si_signo) {
		info->si_signo = signr;
		info->si_errno = 0;
		info->si_code = SI_USER;
2137
		rcu_read_lock();
R
Roland McGrath 已提交
2138
		info->si_pid = task_pid_vnr(current->parent);
2139 2140
		info->si_uid = from_kuid_munged(current_user_ns(),
						task_uid(current->parent));
2141
		rcu_read_unlock();
R
Roland McGrath 已提交
2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152
	}

	/* If the (new) signal is now blocked, requeue it.  */
	if (sigismember(&current->blocked, signr)) {
		specific_send_sig_info(signr, info, current);
		signr = 0;
	}

	return signr;
}

2153
int get_signal(struct ksignal *ksig)
L
Linus Torvalds 已提交
2154
{
2155 2156 2157
	struct sighand_struct *sighand = current->sighand;
	struct signal_struct *signal = current->signal;
	int signr;
L
Linus Torvalds 已提交
2158

2159 2160
	if (unlikely(current->task_works))
		task_work_run();
2161

2162 2163 2164
	if (unlikely(uprobe_deny_signal()))
		return 0;

R
Roland McGrath 已提交
2165
	/*
2166 2167 2168
	 * Do this once, we can't return to user-mode if freezing() == T.
	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
	 * thus do not need another check after return.
R
Roland McGrath 已提交
2169
	 */
2170 2171
	try_to_freeze();

2172
relock:
2173
	spin_lock_irq(&sighand->siglock);
2174 2175 2176 2177 2178
	/*
	 * Every stopped thread goes here after wakeup. Check to see if
	 * we should notify the parent, prepare_signal(SIGCONT) encodes
	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
	 */
2179
	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2180 2181 2182 2183 2184 2185 2186
		int why;

		if (signal->flags & SIGNAL_CLD_CONTINUED)
			why = CLD_CONTINUED;
		else
			why = CLD_STOPPED;

2187
		signal->flags &= ~SIGNAL_CLD_MASK;
2188

2189
		spin_unlock_irq(&sighand->siglock);
R
Roland McGrath 已提交
2190

2191 2192 2193 2194 2195 2196 2197 2198
		/*
		 * Notify the parent that we're continuing.  This event is
		 * always per-process and doesn't make whole lot of sense
		 * for ptracers, who shouldn't consume the state via
		 * wait(2) either, but, for backward compatibility, notify
		 * the ptracer of the group leader too unless it's gonna be
		 * a duplicate.
		 */
T
Tejun Heo 已提交
2199
		read_lock(&tasklist_lock);
2200 2201
		do_notify_parent_cldstop(current, false, why);

2202 2203 2204
		if (ptrace_reparented(current->group_leader))
			do_notify_parent_cldstop(current->group_leader,
						true, why);
T
Tejun Heo 已提交
2205
		read_unlock(&tasklist_lock);
2206

2207 2208 2209
		goto relock;
	}

L
Linus Torvalds 已提交
2210 2211
	for (;;) {
		struct k_sigaction *ka;
2212

T
Tejun Heo 已提交
2213 2214
		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
		    do_signal_stop(0))
2215
			goto relock;
2216

2217 2218 2219 2220 2221
		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
			do_jobctl_trap();
			spin_unlock_irq(&sighand->siglock);
			goto relock;
		}
L
Linus Torvalds 已提交
2222

2223
		signr = dequeue_signal(current, &current->blocked, &ksig->info);
2224

T
Tejun Heo 已提交
2225 2226
		if (!signr)
			break; /* will return 0 */
2227

2228
		if (unlikely(current->ptrace) && signr != SIGKILL) {
2229
			signr = ptrace_signal(signr, &ksig->info);
T
Tejun Heo 已提交
2230 2231
			if (!signr)
				continue;
L
Linus Torvalds 已提交
2232 2233
		}

T
Tejun Heo 已提交
2234 2235
		ka = &sighand->action[signr-1];

2236
		/* Trace actually delivered signals. */
2237
		trace_signal_deliver(signr, &ksig->info, ka);
2238

L
Linus Torvalds 已提交
2239 2240 2241 2242
		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
			continue;
		if (ka->sa.sa_handler != SIG_DFL) {
			/* Run the handler.  */
2243
			ksig->ka = *ka;
L
Linus Torvalds 已提交
2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256

			if (ka->sa.sa_flags & SA_ONESHOT)
				ka->sa.sa_handler = SIG_DFL;

			break; /* will return non-zero "signr" value */
		}

		/*
		 * Now we are doing the default action for this signal.
		 */
		if (sig_kernel_ignore(signr)) /* Default is nothing. */
			continue;

2257
		/*
2258
		 * Global init gets no signals it doesn't want.
2259 2260 2261 2262 2263 2264 2265
		 * Container-init gets no signals it doesn't want from same
		 * container.
		 *
		 * Note that if global/container-init sees a sig_kernel_only()
		 * signal here, the signal must have been generated internally
		 * or must have come from an ancestor namespace. In either
		 * case, the signal cannot be dropped.
2266
		 */
2267
		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2268
				!sig_kernel_only(signr))
L
Linus Torvalds 已提交
2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282
			continue;

		if (sig_kernel_stop(signr)) {
			/*
			 * The default action is to stop all threads in
			 * the thread group.  The job control signals
			 * do nothing in an orphaned pgrp, but SIGSTOP
			 * always works.  Note that siglock needs to be
			 * dropped during the call to is_orphaned_pgrp()
			 * because of lock ordering with tasklist_lock.
			 * This allows an intervening SIGCONT to be posted.
			 * We need to check for that and bail out if necessary.
			 */
			if (signr != SIGSTOP) {
2283
				spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2284 2285 2286

				/* signals can be posted during this window */

2287
				if (is_current_pgrp_orphaned())
L
Linus Torvalds 已提交
2288 2289
					goto relock;

2290
				spin_lock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2291 2292
			}

2293
			if (likely(do_signal_stop(ksig->info.si_signo))) {
L
Linus Torvalds 已提交
2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304
				/* It released the siglock.  */
				goto relock;
			}

			/*
			 * We didn't actually stop, due to a race
			 * with SIGCONT or something like that.
			 */
			continue;
		}

2305
		spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2306 2307 2308 2309 2310

		/*
		 * Anything else is fatal, maybe with a core dump.
		 */
		current->flags |= PF_SIGNALED;
2311

L
Linus Torvalds 已提交
2312
		if (sig_kernel_coredump(signr)) {
2313
			if (print_fatal_signals)
2314
				print_fatal_signal(ksig->info.si_signo);
2315
			proc_coredump_connector(current);
L
Linus Torvalds 已提交
2316 2317 2318 2319 2320 2321 2322 2323
			/*
			 * If it was able to dump core, this kills all
			 * other threads in the group and synchronizes with
			 * their demise.  If we lost the race with another
			 * thread getting here, it set group_exit_code
			 * first and our do_group_exit call below will use
			 * that value and ignore the one we pass it.
			 */
2324
			do_coredump(&ksig->info);
L
Linus Torvalds 已提交
2325 2326 2327 2328 2329
		}

		/*
		 * Death signals, no core dump.
		 */
2330
		do_group_exit(ksig->info.si_signo);
L
Linus Torvalds 已提交
2331 2332
		/* NOTREACHED */
	}
2333
	spin_unlock_irq(&sighand->siglock);
2334 2335 2336

	ksig->sig = signr;
	return ksig->sig > 0;
L
Linus Torvalds 已提交
2337 2338
}

2339
/**
A
Al Viro 已提交
2340
 * signal_delivered - 
R
Richard Weinberger 已提交
2341
 * @ksig:		kernel signal struct
A
Al Viro 已提交
2342
 * @stepping:		nonzero if debugger single-step or block-step in use
2343
 *
2344
 * This function should be called when a signal has successfully been
R
Richard Weinberger 已提交
2345
 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
A
Al Viro 已提交
2346
 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
R
Richard Weinberger 已提交
2347
 * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2348
 */
R
Richard Weinberger 已提交
2349
static void signal_delivered(struct ksignal *ksig, int stepping)
2350 2351 2352
{
	sigset_t blocked;

2353 2354 2355 2356 2357 2358
	/* A signal was successfully delivered, and the
	   saved sigmask was stored on the signal frame,
	   and will be restored by sigreturn.  So we can
	   simply clear the restore sigmask flag.  */
	clear_restore_sigmask();

R
Richard Weinberger 已提交
2359 2360 2361
	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
		sigaddset(&blocked, ksig->sig);
2362
	set_current_blocked(&blocked);
2363
	tracehook_signal_handler(stepping);
2364 2365
}

A
Al Viro 已提交
2366 2367 2368 2369 2370
void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
{
	if (failed)
		force_sigsegv(ksig->sig, current);
	else
R
Richard Weinberger 已提交
2371
		signal_delivered(ksig, stepping);
A
Al Viro 已提交
2372 2373
}

2374 2375
/*
 * It could be that complete_signal() picked us to notify about the
2376 2377
 * group-wide signal. Other threads should be notified now to take
 * the shared signals in @which since we will not.
2378
 */
2379
static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2380
{
2381
	sigset_t retarget;
2382 2383
	struct task_struct *t;

2384 2385 2386 2387
	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
	if (sigisemptyset(&retarget))
		return;

2388 2389
	t = tsk;
	while_each_thread(tsk, t) {
2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402
		if (t->flags & PF_EXITING)
			continue;

		if (!has_pending_signals(&retarget, &t->blocked))
			continue;
		/* Remove the signals this thread can handle. */
		sigandsets(&retarget, &retarget, &t->blocked);

		if (!signal_pending(t))
			signal_wake_up(t, 0);

		if (sigisemptyset(&retarget))
			break;
2403 2404 2405
	}
}

O
Oleg Nesterov 已提交
2406 2407 2408
void exit_signals(struct task_struct *tsk)
{
	int group_stop = 0;
2409
	sigset_t unblocked;
O
Oleg Nesterov 已提交
2410

2411 2412 2413 2414
	/*
	 * @tsk is about to have PF_EXITING set - lock out users which
	 * expect stable threadgroup.
	 */
2415
	cgroup_threadgroup_change_begin(tsk);
2416

2417 2418
	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
		tsk->flags |= PF_EXITING;
2419
		cgroup_threadgroup_change_end(tsk);
2420
		return;
O
Oleg Nesterov 已提交
2421 2422
	}

2423
	spin_lock_irq(&tsk->sighand->siglock);
O
Oleg Nesterov 已提交
2424 2425 2426 2427 2428
	/*
	 * From now this task is not visible for group-wide signals,
	 * see wants_signal(), do_signal_stop().
	 */
	tsk->flags |= PF_EXITING;
2429

2430
	cgroup_threadgroup_change_end(tsk);
2431

2432 2433 2434
	if (!signal_pending(tsk))
		goto out;

2435 2436 2437
	unblocked = tsk->blocked;
	signotset(&unblocked);
	retarget_shared_pending(tsk, &unblocked);
2438

2439
	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2440
	    task_participate_group_stop(tsk))
T
Tejun Heo 已提交
2441
		group_stop = CLD_STOPPED;
2442
out:
O
Oleg Nesterov 已提交
2443 2444
	spin_unlock_irq(&tsk->sighand->siglock);

2445 2446 2447 2448
	/*
	 * If group stop has completed, deliver the notification.  This
	 * should always go to the real parent of the group leader.
	 */
2449
	if (unlikely(group_stop)) {
O
Oleg Nesterov 已提交
2450
		read_lock(&tasklist_lock);
2451
		do_notify_parent_cldstop(tsk, false, group_stop);
O
Oleg Nesterov 已提交
2452 2453 2454 2455
		read_unlock(&tasklist_lock);
	}
}

L
Linus Torvalds 已提交
2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467
EXPORT_SYMBOL(recalc_sigpending);
EXPORT_SYMBOL_GPL(dequeue_signal);
EXPORT_SYMBOL(flush_signals);
EXPORT_SYMBOL(force_sig);
EXPORT_SYMBOL(send_sig);
EXPORT_SYMBOL(send_sig_info);
EXPORT_SYMBOL(sigprocmask);

/*
 * System call entry points.
 */

2468 2469 2470
/**
 *  sys_restart_syscall - restart a system call
 */
2471
SYSCALL_DEFINE0(restart_syscall)
L
Linus Torvalds 已提交
2472
{
2473
	struct restart_block *restart = &current->restart_block;
L
Linus Torvalds 已提交
2474 2475 2476 2477 2478 2479 2480 2481
	return restart->fn(restart);
}

long do_no_restart_syscall(struct restart_block *param)
{
	return -EINTR;
}

2482 2483 2484 2485 2486
static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
{
	if (signal_pending(tsk) && !thread_group_empty(tsk)) {
		sigset_t newblocked;
		/* A set of now blocked but previously unblocked signals. */
2487
		sigandnsets(&newblocked, newset, &current->blocked);
2488 2489 2490 2491 2492 2493
		retarget_shared_pending(tsk, &newblocked);
	}
	tsk->blocked = *newset;
	recalc_sigpending();
}

2494 2495 2496 2497 2498 2499
/**
 * set_current_blocked - change current->blocked mask
 * @newset: new mask
 *
 * It is wrong to change ->blocked directly, this helper should be used
 * to ensure the process can't miss a shared signal we are going to block.
L
Linus Torvalds 已提交
2500
 */
2501 2502 2503
void set_current_blocked(sigset_t *newset)
{
	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2504
	__set_current_blocked(newset);
2505 2506 2507
}

void __set_current_blocked(const sigset_t *newset)
2508 2509 2510
{
	struct task_struct *tsk = current;

2511 2512 2513 2514 2515 2516 2517
	/*
	 * In case the signal mask hasn't changed, there is nothing we need
	 * to do. The current->blocked shouldn't be modified by other task.
	 */
	if (sigequalsets(&tsk->blocked, newset))
		return;

2518
	spin_lock_irq(&tsk->sighand->siglock);
2519
	__set_task_blocked(tsk, newset);
2520 2521
	spin_unlock_irq(&tsk->sighand->siglock);
}
L
Linus Torvalds 已提交
2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532

/*
 * This is also useful for kernel threads that want to temporarily
 * (or permanently) block certain signals.
 *
 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
 * interface happily blocks "unblockable" signals like SIGKILL
 * and friends.
 */
int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
{
2533 2534
	struct task_struct *tsk = current;
	sigset_t newset;
L
Linus Torvalds 已提交
2535

2536
	/* Lockless, only current can change ->blocked, never from irq */
2537
	if (oldset)
2538
		*oldset = tsk->blocked;
2539

L
Linus Torvalds 已提交
2540 2541
	switch (how) {
	case SIG_BLOCK:
2542
		sigorsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2543 2544
		break;
	case SIG_UNBLOCK:
2545
		sigandnsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2546 2547
		break;
	case SIG_SETMASK:
2548
		newset = *set;
L
Linus Torvalds 已提交
2549 2550
		break;
	default:
2551
		return -EINVAL;
L
Linus Torvalds 已提交
2552
	}
2553

2554
	__set_current_blocked(&newset);
2555
	return 0;
L
Linus Torvalds 已提交
2556 2557
}

2558 2559 2560
/**
 *  sys_rt_sigprocmask - change the list of currently blocked signals
 *  @how: whether to add, remove, or set signals
R
Randy Dunlap 已提交
2561
 *  @nset: stores pending signals
2562 2563 2564
 *  @oset: previous value of signal mask if non-null
 *  @sigsetsize: size of sigset_t type
 */
2565
SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2566
		sigset_t __user *, oset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2567 2568
{
	sigset_t old_set, new_set;
2569
	int error;
L
Linus Torvalds 已提交
2570 2571 2572

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
2573
		return -EINVAL;
L
Linus Torvalds 已提交
2574

2575 2576 2577 2578 2579
	old_set = current->blocked;

	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2580 2581
		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

2582
		error = sigprocmask(how, &new_set, NULL);
L
Linus Torvalds 已提交
2583
		if (error)
2584 2585
			return error;
	}
L
Linus Torvalds 已提交
2586

2587 2588 2589
	if (oset) {
		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2590
	}
2591 2592

	return 0;
L
Linus Torvalds 已提交
2593 2594
}

A
Al Viro 已提交
2595 2596 2597
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
		compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
L
Linus Torvalds 已提交
2598
{
A
Al Viro 已提交
2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622
#ifdef __BIG_ENDIAN
	sigset_t old_set = current->blocked;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (nset) {
		compat_sigset_t new32;
		sigset_t new_set;
		int error;
		if (copy_from_user(&new32, nset, sizeof(compat_sigset_t)))
			return -EFAULT;

		sigset_from_compat(&new_set, &new32);
		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

		error = sigprocmask(how, &new_set, NULL);
		if (error)
			return error;
	}
	if (oset) {
		compat_sigset_t old32;
		sigset_to_compat(&old32, &old_set);
A
Al Viro 已提交
2623
		if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
A
Al Viro 已提交
2624 2625 2626 2627 2628 2629 2630 2631 2632
			return -EFAULT;
	}
	return 0;
#else
	return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
				  (sigset_t __user *)oset, sigsetsize);
#endif
}
#endif
L
Linus Torvalds 已提交
2633

A
Al Viro 已提交
2634
static int do_sigpending(void *set, unsigned long sigsetsize)
L
Linus Torvalds 已提交
2635 2636
{
	if (sigsetsize > sizeof(sigset_t))
A
Al Viro 已提交
2637
		return -EINVAL;
L
Linus Torvalds 已提交
2638 2639

	spin_lock_irq(&current->sighand->siglock);
A
Al Viro 已提交
2640
	sigorsets(set, &current->pending.signal,
L
Linus Torvalds 已提交
2641 2642 2643 2644
		  &current->signal->shared_pending.signal);
	spin_unlock_irq(&current->sighand->siglock);

	/* Outside the lock because only this thread touches it.  */
A
Al Viro 已提交
2645 2646
	sigandsets(set, &current->blocked, set);
	return 0;
2647
}
L
Linus Torvalds 已提交
2648

2649 2650 2651
/**
 *  sys_rt_sigpending - examine a pending signal that has been raised
 *			while blocked
2652
 *  @uset: stores pending signals
2653 2654
 *  @sigsetsize: size of sigset_t type or larger
 */
A
Al Viro 已提交
2655
SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2656
{
A
Al Viro 已提交
2657 2658 2659 2660 2661 2662 2663 2664 2665 2666
	sigset_t set;
	int err = do_sigpending(&set, sigsetsize);
	if (!err && copy_to_user(uset, &set, sigsetsize))
		err = -EFAULT;
	return err;
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
		compat_size_t, sigsetsize)
L
Linus Torvalds 已提交
2667
{
A
Al Viro 已提交
2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681
#ifdef __BIG_ENDIAN
	sigset_t set;
	int err = do_sigpending(&set, sigsetsize);
	if (!err) {
		compat_sigset_t set32;
		sigset_to_compat(&set32, &set);
		/* we can get here only if sigsetsize <= sizeof(set) */
		if (copy_to_user(uset, &set32, sigsetsize))
			err = -EFAULT;
	}
	return err;
#else
	return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
#endif
L
Linus Torvalds 已提交
2682
}
A
Al Viro 已提交
2683
#endif
L
Linus Torvalds 已提交
2684 2685 2686

#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER

A
Al Viro 已提交
2687
int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
L
Linus Torvalds 已提交
2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698
{
	int err;

	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
		return -EFAULT;
	if (from->si_code < 0)
		return __copy_to_user(to, from, sizeof(siginfo_t))
			? -EFAULT : 0;
	/*
	 * If you change siginfo_t structure, please be sure
	 * this code is fixed accordingly.
2699 2700
	 * Please remember to update the signalfd_copyinfo() function
	 * inside fs/signalfd.c too, in case siginfo_t changes.
L
Linus Torvalds 已提交
2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725
	 * It should never copy any pad contained in the structure
	 * to avoid security leaks, but must copy the generic
	 * 3 ints plus the relevant union member.
	 */
	err = __put_user(from->si_signo, &to->si_signo);
	err |= __put_user(from->si_errno, &to->si_errno);
	err |= __put_user((short)from->si_code, &to->si_code);
	switch (from->si_code & __SI_MASK) {
	case __SI_KILL:
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		break;
	case __SI_TIMER:
		 err |= __put_user(from->si_tid, &to->si_tid);
		 err |= __put_user(from->si_overrun, &to->si_overrun);
		 err |= __put_user(from->si_ptr, &to->si_ptr);
		break;
	case __SI_POLL:
		err |= __put_user(from->si_band, &to->si_band);
		err |= __put_user(from->si_fd, &to->si_fd);
		break;
	case __SI_FAULT:
		err |= __put_user(from->si_addr, &to->si_addr);
#ifdef __ARCH_SI_TRAPNO
		err |= __put_user(from->si_trapno, &to->si_trapno);
A
Andi Kleen 已提交
2726 2727
#endif
#ifdef BUS_MCEERR_AO
2728
		/*
A
Andi Kleen 已提交
2729
		 * Other callers might not initialize the si_lsb field,
2730
		 * so check explicitly for the right codes here.
A
Andi Kleen 已提交
2731
		 */
2732 2733
		if (from->si_signo == SIGBUS &&
		    (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
A
Andi Kleen 已提交
2734
			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2735 2736
#endif
#ifdef SEGV_BNDERR
2737 2738 2739 2740
		if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
			err |= __put_user(from->si_lower, &to->si_lower);
			err |= __put_user(from->si_upper, &to->si_upper);
		}
2741 2742 2743 2744
#endif
#ifdef SEGV_PKUERR
		if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
			err |= __put_user(from->si_pkey, &to->si_pkey);
L
Linus Torvalds 已提交
2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759
#endif
		break;
	case __SI_CHLD:
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		err |= __put_user(from->si_status, &to->si_status);
		err |= __put_user(from->si_utime, &to->si_utime);
		err |= __put_user(from->si_stime, &to->si_stime);
		break;
	case __SI_RT: /* This is not generated by the kernel as of now. */
	case __SI_MESGQ: /* But this is */
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		err |= __put_user(from->si_ptr, &to->si_ptr);
		break;
2760 2761 2762 2763 2764 2765 2766
#ifdef __ARCH_SIGSYS
	case __SI_SYS:
		err |= __put_user(from->si_call_addr, &to->si_call_addr);
		err |= __put_user(from->si_syscall, &to->si_syscall);
		err |= __put_user(from->si_arch, &to->si_arch);
		break;
#endif
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2767 2768 2769 2770 2771 2772 2773 2774 2775 2776
	default: /* this is just in case for now ... */
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		break;
	}
	return err;
}

#endif

2777 2778 2779 2780 2781 2782
/**
 *  do_sigtimedwait - wait for queued signals specified in @which
 *  @which: queued signals to wait for
 *  @info: if non-null, the signal's siginfo is returned here
 *  @ts: upper bound on process time suspension
 */
2783
static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2784
		    const struct timespec *ts)
2785
{
T
Thomas Gleixner 已提交
2786
	ktime_t *to = NULL, timeout = KTIME_MAX;
2787 2788
	struct task_struct *tsk = current;
	sigset_t mask = *which;
2789
	int sig, ret = 0;
2790 2791 2792 2793

	if (ts) {
		if (!timespec_valid(ts))
			return -EINVAL;
2794 2795
		timeout = timespec_to_ktime(*ts);
		to = &timeout;
2796 2797 2798 2799 2800 2801 2802 2803 2804 2805
	}

	/*
	 * Invert the set of allowed signals to get those we want to block.
	 */
	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
	signotset(&mask);

	spin_lock_irq(&tsk->sighand->siglock);
	sig = dequeue_signal(tsk, &mask, info);
T
Thomas Gleixner 已提交
2806
	if (!sig && timeout) {
2807 2808 2809
		/*
		 * None ready, temporarily unblock those we're interested
		 * while we are sleeping in so that we'll be awakened when
2810 2811
		 * they arrive. Unblocking is always fine, we can avoid
		 * set_current_blocked().
2812 2813 2814 2815 2816 2817
		 */
		tsk->real_blocked = tsk->blocked;
		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
		recalc_sigpending();
		spin_unlock_irq(&tsk->sighand->siglock);

2818 2819 2820
		__set_current_state(TASK_INTERRUPTIBLE);
		ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
							 HRTIMER_MODE_REL);
2821
		spin_lock_irq(&tsk->sighand->siglock);
2822
		__set_task_blocked(tsk, &tsk->real_blocked);
2823
		sigemptyset(&tsk->real_blocked);
2824
		sig = dequeue_signal(tsk, &mask, info);
2825 2826 2827 2828 2829
	}
	spin_unlock_irq(&tsk->sighand->siglock);

	if (sig)
		return sig;
2830
	return ret ? -EINTR : -EAGAIN;
2831 2832
}

2833 2834 2835 2836 2837 2838 2839 2840
/**
 *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
 *			in @uthese
 *  @uthese: queued signals to wait for
 *  @uinfo: if non-null, the signal's siginfo is returned here
 *  @uts: upper bound on process time suspension
 *  @sigsetsize: size of sigset_t type
 */
2841 2842 2843
SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
		siginfo_t __user *, uinfo, const struct timespec __user *, uts,
		size_t, sigsetsize)
L
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2844 2845 2846 2847
{
	sigset_t these;
	struct timespec ts;
	siginfo_t info;
2848
	int ret;
L
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2849 2850 2851 2852 2853 2854 2855

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (copy_from_user(&these, uthese, sizeof(these)))
		return -EFAULT;
2856

L
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2857 2858 2859 2860 2861
	if (uts) {
		if (copy_from_user(&ts, uts, sizeof(ts)))
			return -EFAULT;
	}

2862
	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
L
Linus Torvalds 已提交
2863

2864 2865 2866
	if (ret > 0 && uinfo) {
		if (copy_siginfo_to_user(uinfo, &info))
			ret = -EFAULT;
L
Linus Torvalds 已提交
2867 2868 2869 2870 2871
	}

	return ret;
}

2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
		struct compat_siginfo __user *, uinfo,
		struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
{
	compat_sigset_t s32;
	sigset_t s;
	struct timespec t;
	siginfo_t info;
	long ret;

	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (copy_from_user(&s32, uthese, sizeof(compat_sigset_t)))
		return -EFAULT;
	sigset_from_compat(&s, &s32);

	if (uts) {
		if (compat_get_timespec(&t, uts))
			return -EFAULT;
	}

	ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);

	if (ret > 0 && uinfo) {
		if (copy_siginfo_to_user32(uinfo, &info))
			ret = -EFAULT;
	}

	return ret;
}
#endif

2906 2907 2908 2909 2910
/**
 *  sys_kill - send a signal to a process
 *  @pid: the PID of the process
 *  @sig: signal to be sent
 */
2911
SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2912 2913 2914 2915 2916 2917
{
	struct siginfo info;

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_USER;
2918
	info.si_pid = task_tgid_vnr(current);
2919
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
2920 2921 2922 2923

	return kill_something_info(sig, &info, pid);
}

T
Thomas Gleixner 已提交
2924 2925
static int
do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
L
Linus Torvalds 已提交
2926 2927
{
	struct task_struct *p;
T
Thomas Gleixner 已提交
2928
	int error = -ESRCH;
L
Linus Torvalds 已提交
2929

2930
	rcu_read_lock();
2931
	p = find_task_by_vpid(pid);
2932
	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
T
Thomas Gleixner 已提交
2933
		error = check_kill_permission(sig, info, p);
L
Linus Torvalds 已提交
2934 2935 2936 2937
		/*
		 * The null signal is a permissions and process existence
		 * probe.  No signal is actually delivered.
		 */
2938 2939 2940 2941 2942 2943 2944 2945 2946
		if (!error && sig) {
			error = do_send_sig_info(sig, info, p, false);
			/*
			 * If lock_task_sighand() failed we pretend the task
			 * dies after receiving the signal. The window is tiny,
			 * and the signal is private anyway.
			 */
			if (unlikely(error == -ESRCH))
				error = 0;
L
Linus Torvalds 已提交
2947 2948
		}
	}
2949
	rcu_read_unlock();
2950

L
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2951 2952 2953
	return error;
}

T
Thomas Gleixner 已提交
2954 2955
static int do_tkill(pid_t tgid, pid_t pid, int sig)
{
2956
	struct siginfo info = {};
T
Thomas Gleixner 已提交
2957 2958 2959 2960 2961

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_TKILL;
	info.si_pid = task_tgid_vnr(current);
2962
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
T
Thomas Gleixner 已提交
2963 2964 2965 2966

	return do_send_specific(tgid, pid, sig, &info);
}

2967 2968 2969 2970 2971 2972
/**
 *  sys_tgkill - send signal to one specific thread
 *  @tgid: the thread group ID of the thread
 *  @pid: the PID of the thread
 *  @sig: signal to be sent
 *
2973
 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
2974 2975 2976
 *  exists but it's not belonging to the target process anymore. This
 *  method solves the problem of threads exiting and PIDs getting reused.
 */
2977
SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2978 2979 2980 2981 2982 2983 2984 2985
{
	/* This is only valid for single tasks */
	if (pid <= 0 || tgid <= 0)
		return -EINVAL;

	return do_tkill(tgid, pid, sig);
}

2986 2987 2988 2989 2990
/**
 *  sys_tkill - send signal to one specific task
 *  @pid: the PID of the task
 *  @sig: signal to be sent
 *
L
Linus Torvalds 已提交
2991 2992
 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
 */
2993
SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2994 2995 2996 2997 2998
{
	/* This is only valid for single tasks */
	if (pid <= 0)
		return -EINVAL;

2999
	return do_tkill(0, pid, sig);
L
Linus Torvalds 已提交
3000 3001
}

A
Al Viro 已提交
3002 3003 3004 3005 3006
static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
{
	/* Not even root can pretend to send signals from the kernel.
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
3007
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3008
	    (task_pid_vnr(current) != pid))
A
Al Viro 已提交
3009
		return -EPERM;
3010

A
Al Viro 已提交
3011 3012 3013 3014 3015 3016
	info->si_signo = sig;

	/* POSIX.1b doesn't mention process groups.  */
	return kill_proc_info(sig, info, pid);
}

3017 3018 3019 3020 3021 3022
/**
 *  sys_rt_sigqueueinfo - send signal information to a signal
 *  @pid: the PID of the thread
 *  @sig: signal to be sent
 *  @uinfo: signal info to be sent
 */
3023 3024
SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
		siginfo_t __user *, uinfo)
L
Linus Torvalds 已提交
3025 3026 3027 3028
{
	siginfo_t info;
	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
		return -EFAULT;
A
Al Viro 已提交
3029 3030
	return do_rt_sigqueueinfo(pid, sig, &info);
}
L
Linus Torvalds 已提交
3031

A
Al Viro 已提交
3032 3033 3034 3035 3036 3037
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
3038
	siginfo_t info = {};
A
Al Viro 已提交
3039 3040 3041 3042
	int ret = copy_siginfo_from_user32(&info, uinfo);
	if (unlikely(ret))
		return ret;
	return do_rt_sigqueueinfo(pid, sig, &info);
L
Linus Torvalds 已提交
3043
}
A
Al Viro 已提交
3044
#endif
L
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3045

3046
static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3047 3048 3049 3050 3051 3052
{
	/* This is only valid for single tasks */
	if (pid <= 0 || tgid <= 0)
		return -EINVAL;

	/* Not even root can pretend to send signals from the kernel.
3053 3054
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
3055 3056
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
	    (task_pid_vnr(current) != pid))
3057
		return -EPERM;
3058

3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074
	info->si_signo = sig;

	return do_send_specific(tgid, pid, sig, info);
}

SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
		siginfo_t __user *, uinfo)
{
	siginfo_t info;

	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
		return -EFAULT;

	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
}

3075 3076 3077 3078 3079 3080 3081
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
			compat_pid_t, tgid,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
3082
	siginfo_t info = {};
3083 3084 3085 3086 3087 3088 3089

	if (copy_siginfo_from_user32(&info, uinfo))
		return -EFAULT;
	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
}
#endif

3090
/*
3091
 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3092
 */
3093
void kernel_sigaction(int sig, __sighandler_t action)
3094
{
3095
	spin_lock_irq(&current->sighand->siglock);
3096 3097 3098
	current->sighand->action[sig - 1].sa.sa_handler = action;
	if (action == SIG_IGN) {
		sigset_t mask;
3099

3100 3101
		sigemptyset(&mask);
		sigaddset(&mask, sig);
3102

3103 3104 3105 3106
		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
		flush_sigqueue_mask(&mask, &current->pending);
		recalc_sigpending();
	}
3107 3108
	spin_unlock_irq(&current->sighand->siglock);
}
3109
EXPORT_SYMBOL(kernel_sigaction);
3110

3111 3112 3113 3114 3115
void __weak sigaction_compat_abi(struct k_sigaction *act,
		struct k_sigaction *oact)
{
}

3116
int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
L
Linus Torvalds 已提交
3117
{
3118
	struct task_struct *p = current, *t;
L
Linus Torvalds 已提交
3119
	struct k_sigaction *k;
3120
	sigset_t mask;
L
Linus Torvalds 已提交
3121

3122
	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
L
Linus Torvalds 已提交
3123 3124
		return -EINVAL;

3125
	k = &p->sighand->action[sig-1];
L
Linus Torvalds 已提交
3126

3127
	spin_lock_irq(&p->sighand->siglock);
L
Linus Torvalds 已提交
3128 3129 3130
	if (oact)
		*oact = *k;

3131 3132
	sigaction_compat_abi(act, oact);

L
Linus Torvalds 已提交
3133
	if (act) {
3134 3135
		sigdelsetmask(&act->sa.sa_mask,
			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3136
		*k = *act;
L
Linus Torvalds 已提交
3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147
		/*
		 * POSIX 3.3.1.3:
		 *  "Setting a signal action to SIG_IGN for a signal that is
		 *   pending shall cause the pending signal to be discarded,
		 *   whether or not it is blocked."
		 *
		 *  "Setting a signal action to SIG_DFL for a signal that is
		 *   pending and whose default action is to ignore the signal
		 *   (for example, SIGCHLD), shall cause the pending signal to
		 *   be discarded, whether or not it is blocked"
		 */
3148
		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3149 3150
			sigemptyset(&mask);
			sigaddset(&mask, sig);
3151 3152
			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
			for_each_thread(p, t)
3153
				flush_sigqueue_mask(&mask, &t->pending);
L
Linus Torvalds 已提交
3154 3155 3156
		}
	}

3157
	spin_unlock_irq(&p->sighand->siglock);
L
Linus Torvalds 已提交
3158 3159 3160
	return 0;
}

3161
static int
3162
do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
L
Linus Torvalds 已提交
3163
{
3164
	struct task_struct *t = current;
L
Linus Torvalds 已提交
3165

3166 3167 3168 3169 3170 3171 3172
	if (oss) {
		memset(oss, 0, sizeof(stack_t));
		oss->ss_sp = (void __user *) t->sas_ss_sp;
		oss->ss_size = t->sas_ss_size;
		oss->ss_flags = sas_ss_flags(sp) |
			(current->sas_ss_flags & SS_FLAG_BITS);
	}
L
Linus Torvalds 已提交
3173

3174 3175 3176 3177
	if (ss) {
		void __user *ss_sp = ss->ss_sp;
		size_t ss_size = ss->ss_size;
		unsigned ss_flags = ss->ss_flags;
3178
		int ss_mode;
L
Linus Torvalds 已提交
3179

3180 3181
		if (unlikely(on_sig_stack(sp)))
			return -EPERM;
L
Linus Torvalds 已提交
3182

3183
		ss_mode = ss_flags & ~SS_FLAG_BITS;
3184 3185 3186
		if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
				ss_mode != 0))
			return -EINVAL;
L
Linus Torvalds 已提交
3187

3188
		if (ss_mode == SS_DISABLE) {
L
Linus Torvalds 已提交
3189 3190 3191
			ss_size = 0;
			ss_sp = NULL;
		} else {
3192 3193
			if (unlikely(ss_size < MINSIGSTKSZ))
				return -ENOMEM;
L
Linus Torvalds 已提交
3194 3195
		}

3196 3197 3198
		t->sas_ss_sp = (unsigned long) ss_sp;
		t->sas_ss_size = ss_size;
		t->sas_ss_flags = ss_flags;
L
Linus Torvalds 已提交
3199
	}
3200
	return 0;
L
Linus Torvalds 已提交
3201
}
3202

3203 3204
SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
{
3205 3206 3207 3208 3209 3210 3211 3212 3213
	stack_t new, old;
	int err;
	if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
		return -EFAULT;
	err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
			      current_user_stack_pointer());
	if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
		err = -EFAULT;
	return err;
3214
}
L
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3215

A
Al Viro 已提交
3216 3217
int restore_altstack(const stack_t __user *uss)
{
3218 3219 3220 3221
	stack_t new;
	if (copy_from_user(&new, uss, sizeof(stack_t)))
		return -EFAULT;
	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
A
Al Viro 已提交
3222
	/* squash all but EFAULT for now */
3223
	return 0;
A
Al Viro 已提交
3224 3225
}

3226 3227 3228
int __save_altstack(stack_t __user *uss, unsigned long sp)
{
	struct task_struct *t = current;
3229 3230
	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3231
		__put_user(t->sas_ss_size, &uss->ss_size);
3232 3233 3234 3235 3236
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3237 3238
}

A
Al Viro 已提交
3239
#ifdef CONFIG_COMPAT
3240 3241 3242
COMPAT_SYSCALL_DEFINE2(sigaltstack,
			const compat_stack_t __user *, uss_ptr,
			compat_stack_t __user *, uoss_ptr)
A
Al Viro 已提交
3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254
{
	stack_t uss, uoss;
	int ret;

	if (uss_ptr) {
		compat_stack_t uss32;
		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
			return -EFAULT;
		uss.ss_sp = compat_ptr(uss32.ss_sp);
		uss.ss_flags = uss32.ss_flags;
		uss.ss_size = uss32.ss_size;
	}
3255
	ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
A
Al Viro 已提交
3256 3257
			     compat_user_stack_pointer());
	if (ret >= 0 && uoss_ptr)  {
3258 3259 3260 3261 3262 3263
		compat_stack_t old;
		memset(&old, 0, sizeof(old));
		old.ss_sp = ptr_to_compat(uoss.ss_sp);
		old.ss_flags = uoss.ss_flags;
		old.ss_size = uoss.ss_size;
		if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
A
Al Viro 已提交
3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274
			ret = -EFAULT;
	}
	return ret;
}

int compat_restore_altstack(const compat_stack_t __user *uss)
{
	int err = compat_sys_sigaltstack(uss, NULL);
	/* squash all but -EFAULT for now */
	return err == -EFAULT ? err : 0;
}
3275 3276 3277

int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
{
3278
	int err;
3279
	struct task_struct *t = current;
3280 3281 3282
	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
			 &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3283
		__put_user(t->sas_ss_size, &uss->ss_size);
3284 3285 3286 3287 3288
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3289
}
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#endif
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3291 3292 3293

#ifdef __ARCH_WANT_SYS_SIGPENDING

3294 3295 3296 3297
/**
 *  sys_sigpending - examine pending signals
 *  @set: where mask of pending signal is returned
 */
3298
SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
L
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3299
{
A
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3300
	return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 
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3301 3302
}

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3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
{
	sigset_t set;
	int err = do_sigpending(&set, sizeof(old_sigset_t)); 
	if (err == 0)
		if (copy_to_user(set32, &set, sizeof(old_sigset_t)))
			err = -EFAULT;
	return err;
}
#endif

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#endif

#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3318 3319 3320
/**
 *  sys_sigprocmask - examine and change blocked signals
 *  @how: whether to add, remove, or set signals
3321
 *  @nset: signals to add or remove (if non-null)
3322 3323
 *  @oset: previous value of signal mask if non-null
 *
3324 3325 3326
 * Some platforms have their own version with special arguments;
 * others support only sys_rt_sigprocmask.
 */
L
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3327

3328
SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3329
		old_sigset_t __user *, oset)
L
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3330 3331
{
	old_sigset_t old_set, new_set;
3332
	sigset_t new_blocked;
L
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3333

3334
	old_set = current->blocked.sig[0];
L
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3335

3336 3337 3338
	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(*nset)))
			return -EFAULT;
L
Linus Torvalds 已提交
3339

3340
		new_blocked = current->blocked;
L
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3341 3342 3343

		switch (how) {
		case SIG_BLOCK:
3344
			sigaddsetmask(&new_blocked, new_set);
L
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3345 3346
			break;
		case SIG_UNBLOCK:
3347
			sigdelsetmask(&new_blocked, new_set);
L
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3348 3349
			break;
		case SIG_SETMASK:
3350
			new_blocked.sig[0] = new_set;
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3351
			break;
3352 3353
		default:
			return -EINVAL;
L
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		}

3356
		set_current_blocked(&new_blocked);
3357 3358 3359
	}

	if (oset) {
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		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3361
			return -EFAULT;
L
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3362
	}
3363 3364

	return 0;
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}
#endif /* __ARCH_WANT_SYS_SIGPROCMASK */

3368
#ifndef CONFIG_ODD_RT_SIGACTION
3369 3370 3371
/**
 *  sys_rt_sigaction - alter an action taken by a process
 *  @sig: signal to be sent
3372 3373
 *  @act: new sigaction
 *  @oact: used to save the previous sigaction
3374 3375
 *  @sigsetsize: size of sigset_t type
 */
3376 3377 3378 3379
SYSCALL_DEFINE4(rt_sigaction, int, sig,
		const struct sigaction __user *, act,
		struct sigaction __user *, oact,
		size_t, sigsetsize)
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3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401
{
	struct k_sigaction new_sa, old_sa;
	int ret = -EINVAL;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		goto out;

	if (act) {
		if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
			return -EFAULT;
	}

	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);

	if (!ret && oact) {
		if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
			return -EFAULT;
	}
out:
	return ret;
}
A
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3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
		const struct compat_sigaction __user *, act,
		struct compat_sigaction __user *, oact,
		compat_size_t, sigsetsize)
{
	struct k_sigaction new_ka, old_ka;
	compat_sigset_t mask;
#ifdef __ARCH_HAS_SA_RESTORER
	compat_uptr_t restorer;
#endif
	int ret;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(compat_sigset_t))
		return -EINVAL;

	if (act) {
		compat_uptr_t handler;
		ret = get_user(handler, &act->sa_handler);
		new_ka.sa.sa_handler = compat_ptr(handler);
#ifdef __ARCH_HAS_SA_RESTORER
		ret |= get_user(restorer, &act->sa_restorer);
		new_ka.sa.sa_restorer = compat_ptr(restorer);
#endif
		ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3428
		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
A
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3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439
		if (ret)
			return -EFAULT;
		sigset_from_compat(&new_ka.sa.sa_mask, &mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
	if (!ret && oact) {
		sigset_to_compat(&mask, &old_ka.sa.sa_mask);
		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
			       &oact->sa_handler);
		ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3440
		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
A
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3441 3442 3443 3444 3445 3446 3447 3448
#ifdef __ARCH_HAS_SA_RESTORER
		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
				&oact->sa_restorer);
#endif
	}
	return ret;
}
#endif
3449
#endif /* !CONFIG_ODD_RT_SIGACTION */
L
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3450

3451 3452 3453 3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513 3514 3515 3516 3517 3518 3519 3520 3521 3522 3523 3524 3525 3526 3527
#ifdef CONFIG_OLD_SIGACTION
SYSCALL_DEFINE3(sigaction, int, sig,
		const struct old_sigaction __user *, act,
	        struct old_sigaction __user *, oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	if (act) {
		old_sigset_t mask;
		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
		    __get_user(mask, &act->sa_mask))
			return -EFAULT;
#ifdef __ARCH_HAS_KA_RESTORER
		new_ka.ka_restorer = NULL;
#endif
		siginitset(&new_ka.sa.sa_mask, mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

	if (!ret && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
			return -EFAULT;
	}

	return ret;
}
#endif
#ifdef CONFIG_COMPAT_OLD_SIGACTION
COMPAT_SYSCALL_DEFINE3(sigaction, int, sig,
		const struct compat_old_sigaction __user *, act,
	        struct compat_old_sigaction __user *, oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;
	compat_old_sigset_t mask;
	compat_uptr_t handler, restorer;

	if (act) {
		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(handler, &act->sa_handler) ||
		    __get_user(restorer, &act->sa_restorer) ||
		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
		    __get_user(mask, &act->sa_mask))
			return -EFAULT;

#ifdef __ARCH_HAS_KA_RESTORER
		new_ka.ka_restorer = NULL;
#endif
		new_ka.sa.sa_handler = compat_ptr(handler);
		new_ka.sa.sa_restorer = compat_ptr(restorer);
		siginitset(&new_ka.sa.sa_mask, mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

	if (!ret && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(ptr_to_compat(old_ka.sa.sa_handler),
			       &oact->sa_handler) ||
		    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
			       &oact->sa_restorer) ||
		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
			return -EFAULT;
	}
	return ret;
}
#endif
L
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3528

3529
#ifdef CONFIG_SGETMASK_SYSCALL
L
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3530 3531 3532 3533

/*
 * For backwards compatibility.  Functionality superseded by sigprocmask.
 */
3534
SYSCALL_DEFINE0(sgetmask)
L
Linus Torvalds 已提交
3535 3536 3537 3538 3539
{
	/* SMP safe */
	return current->blocked.sig[0];
}

3540
SYSCALL_DEFINE1(ssetmask, int, newmask)
L
Linus Torvalds 已提交
3541
{
3542 3543
	int old = current->blocked.sig[0];
	sigset_t newset;
L
Linus Torvalds 已提交
3544

3545
	siginitset(&newset, newmask);
3546
	set_current_blocked(&newset);
L
Linus Torvalds 已提交
3547 3548 3549

	return old;
}
3550
#endif /* CONFIG_SGETMASK_SYSCALL */
L
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3551 3552 3553 3554 3555

#ifdef __ARCH_WANT_SYS_SIGNAL
/*
 * For backwards compatibility.  Functionality superseded by sigaction.
 */
3556
SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
L
Linus Torvalds 已提交
3557 3558 3559 3560 3561 3562
{
	struct k_sigaction new_sa, old_sa;
	int ret;

	new_sa.sa.sa_handler = handler;
	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3563
	sigemptyset(&new_sa.sa.sa_mask);
L
Linus Torvalds 已提交
3564 3565 3566 3567 3568 3569 3570 3571 3572

	ret = do_sigaction(sig, &new_sa, &old_sa);

	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
}
#endif /* __ARCH_WANT_SYS_SIGNAL */

#ifdef __ARCH_WANT_SYS_PAUSE

3573
SYSCALL_DEFINE0(pause)
L
Linus Torvalds 已提交
3574
{
3575
	while (!signal_pending(current)) {
3576
		__set_current_state(TASK_INTERRUPTIBLE);
3577 3578
		schedule();
	}
L
Linus Torvalds 已提交
3579 3580 3581 3582 3583
	return -ERESTARTNOHAND;
}

#endif

3584
static int sigsuspend(sigset_t *set)
A
Al Viro 已提交
3585 3586 3587 3588
{
	current->saved_sigmask = current->blocked;
	set_current_blocked(set);

3589 3590 3591 3592
	while (!signal_pending(current)) {
		__set_current_state(TASK_INTERRUPTIBLE);
		schedule();
	}
A
Al Viro 已提交
3593 3594 3595 3596
	set_restore_sigmask();
	return -ERESTARTNOHAND;
}

3597 3598 3599 3600 3601 3602
/**
 *  sys_rt_sigsuspend - replace the signal mask for a value with the
 *	@unewset value until a signal is received
 *  @unewset: new signal mask value
 *  @sigsetsize: size of sigset_t type
 */
3603
SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3604 3605 3606 3607 3608 3609 3610 3611 3612
{
	sigset_t newset;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (copy_from_user(&newset, unewset, sizeof(newset)))
		return -EFAULT;
A
Al Viro 已提交
3613
	return sigsuspend(&newset);
3614
}
A
Al Viro 已提交
3615 3616 3617 3618 3619 3620 3621 3622 3623 3624 3625 3626 3627 3628 3629 3630 3631 3632 3633 3634 3635 3636
 
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
{
#ifdef __BIG_ENDIAN
	sigset_t newset;
	compat_sigset_t newset32;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
		return -EFAULT;
	sigset_from_compat(&newset, &newset32);
	return sigsuspend(&newset);
#else
	/* on little-endian bitmaps don't care about granularity */
	return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
#endif
}
#endif
3637

3638 3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649 3650 3651 3652 3653
#ifdef CONFIG_OLD_SIGSUSPEND
SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
{
	sigset_t blocked;
	siginitset(&blocked, mask);
	return sigsuspend(&blocked);
}
#endif
#ifdef CONFIG_OLD_SIGSUSPEND3
SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
{
	sigset_t blocked;
	siginitset(&blocked, mask);
	return sigsuspend(&blocked);
}
#endif
3654

3655
__weak const char *arch_vma_name(struct vm_area_struct *vma)
3656 3657 3658 3659
{
	return NULL;
}

L
Linus Torvalds 已提交
3660 3661
void __init signals_init(void)
{
3662 3663 3664 3665
	/* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
	BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
		!= offsetof(struct siginfo, _sifields._pad));

3666
	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
L
Linus Torvalds 已提交
3667
}
3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682 3683 3684 3685 3686 3687 3688 3689 3690 3691 3692 3693 3694 3695 3696 3697 3698 3699 3700 3701 3702 3703 3704 3705 3706 3707

#ifdef CONFIG_KGDB_KDB
#include <linux/kdb.h>
/*
 * kdb_send_sig_info - Allows kdb to send signals without exposing
 * signal internals.  This function checks if the required locks are
 * available before calling the main signal code, to avoid kdb
 * deadlocks.
 */
void
kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
{
	static struct task_struct *kdb_prev_t;
	int sig, new_t;
	if (!spin_trylock(&t->sighand->siglock)) {
		kdb_printf("Can't do kill command now.\n"
			   "The sigmask lock is held somewhere else in "
			   "kernel, try again later\n");
		return;
	}
	spin_unlock(&t->sighand->siglock);
	new_t = kdb_prev_t != t;
	kdb_prev_t = t;
	if (t->state != TASK_RUNNING && new_t) {
		kdb_printf("Process is not RUNNING, sending a signal from "
			   "kdb risks deadlock\n"
			   "on the run queue locks. "
			   "The signal has _not_ been sent.\n"
			   "Reissue the kill command if you want to risk "
			   "the deadlock.\n");
		return;
	}
	sig = info->si_signo;
	if (send_sig_info(sig, info, t))
		kdb_printf("Fail to deliver Signal %d to process %d.\n",
			   sig, t->pid);
	else
		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
}
#endif	/* CONFIG_KGDB_KDB */