signal.c 94.8 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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#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)
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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);
		__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,
			siginfo_t *info)
{
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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);
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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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	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);
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	if (!signr) {
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		signr = __dequeue_signal(&tsk->signal->shared_pending,
					 mask, info);
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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) {
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				hrtimer_forward(tmr, tmr->base->get_time(),
						tsk->signal->it_real_incr);
				hrtimer_restart(tmr);
			}
		}
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#endif
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	}
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	recalc_sigpending();
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	if (!signr)
		return 0;

	if (unlikely(sig_kernel_stop(signr))) {
609 610 611 612 613 614 615 616 617 618 619 620
		/*
		 * 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.
		 */
621
		current->jobctl |= JOBCTL_STOP_DEQUEUED;
622
	}
623
#ifdef CONFIG_POSIX_TIMERS
624
	if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
L
Linus Torvalds 已提交
625 626 627 628 629 630 631 632 633 634
		/*
		 * 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);
		do_schedule_next_timer(info);
		spin_lock(&tsk->sighand->siglock);
	}
635
#endif
L
Linus Torvalds 已提交
636 637 638 639 640 641 642 643 644 645 646 647 648 649
	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
 */
650
void signal_wake_up_state(struct task_struct *t, unsigned int state)
L
Linus Torvalds 已提交
651 652 653
{
	set_tsk_thread_flag(t, TIF_SIGPENDING);
	/*
654
	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
M
Matthew Wilcox 已提交
655
	 * case. We don't check t->state here because there is a race with it
L
Linus Torvalds 已提交
656 657 658 659
	 * 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.
	 */
660
	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
L
Linus Torvalds 已提交
661 662 663
		kick_process(t);
}

664 665 666 667 668 669
/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 */
670
static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
671 672 673 674 675 676 677 678
{
	struct sigqueue *q, *n;
	sigset_t m;

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

679
	sigandnsets(&s->signal, &s->signal, mask);
680 681 682 683 684 685 686 687
	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
688

689 690 691 692 693 694 695 696 697 698 699
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));
}

700 701 702 703 704 705 706 707
/*
 * 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);

708 709 710 711
	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))
712 713
		return 1;

714
	if (ns_capable(tcred->user_ns, CAP_KILL))
715 716 717 718 719
		return 1;

	return 0;
}

L
Linus Torvalds 已提交
720 721
/*
 * Bad permissions for sending the signal
722
 * - the caller must hold the RCU read lock
L
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723 724 725 726
 */
static int check_kill_permission(int sig, struct siginfo *info,
				 struct task_struct *t)
{
727
	struct pid *sid;
728 729
	int error;

730
	if (!valid_signal(sig))
731 732
		return -EINVAL;

733
	if (!si_fromuser(info))
734
		return 0;
A
Amy Griffis 已提交
735

736 737
	error = audit_signal_info(sig, t); /* Let audit system see the signal */
	if (error)
L
Linus Torvalds 已提交
738
		return error;
739

740
	if (!same_thread_group(current, t) &&
741
	    !kill_ok_by_cred(t)) {
742 743 744 745 746 747 748 749 750 751 752 753 754
		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;
		}
	}
755

A
Amy Griffis 已提交
756
	return security_task_kill(t, info, sig, 0);
L
Linus Torvalds 已提交
757 758
}

759 760 761 762 763 764 765 766
/**
 * 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
767 768 769 770 771
 * 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.
772 773 774 775 776 777 778 779 780 781
 *
 * 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);
782
	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
783 784
}

L
Linus Torvalds 已提交
785
/*
786 787
 * 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
788 789
 * time regardless of blocking, ignoring, or handling.  This does the
 * actual continuing for SIGCONT, but not the actual stopping for stop
790 791 792 793
 * 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
794
 */
795
static bool prepare_signal(int sig, struct task_struct *p, bool force)
L
Linus Torvalds 已提交
796
{
797
	struct signal_struct *signal = p->signal;
L
Linus Torvalds 已提交
798
	struct task_struct *t;
799
	sigset_t flush;
L
Linus Torvalds 已提交
800

801
	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
802
		if (!(signal->flags & SIGNAL_GROUP_EXIT))
803
			return sig == SIGKILL;
L
Linus Torvalds 已提交
804
		/*
805
		 * The process is in the middle of dying, nothing to do.
L
Linus Torvalds 已提交
806
		 */
807
	} else if (sig_kernel_stop(sig)) {
L
Linus Torvalds 已提交
808 809 810
		/*
		 * This is a stop signal.  Remove SIGCONT from all queues.
		 */
811
		siginitset(&flush, sigmask(SIGCONT));
812
		flush_sigqueue_mask(&flush, &signal->shared_pending);
813
		for_each_thread(p, t)
814
			flush_sigqueue_mask(&flush, &t->pending);
L
Linus Torvalds 已提交
815
	} else if (sig == SIGCONT) {
816
		unsigned int why;
L
Linus Torvalds 已提交
817
		/*
818
		 * Remove all stop signals from all queues, wake all threads.
L
Linus Torvalds 已提交
819
		 */
820
		siginitset(&flush, SIG_KERNEL_STOP_MASK);
821
		flush_sigqueue_mask(&flush, &signal->shared_pending);
822
		for_each_thread(p, t) {
823
			flush_sigqueue_mask(&flush, &t->pending);
824
			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
825 826 827 828
			if (likely(!(t->ptrace & PT_SEIZED)))
				wake_up_state(t, __TASK_STOPPED);
			else
				ptrace_trap_notify(t);
829
		}
L
Linus Torvalds 已提交
830

831 832 833 834 835 836 837 838 839
		/*
		 * 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;
840
		if (signal->flags & SIGNAL_STOP_STOPPED)
841
			why |= SIGNAL_CLD_CONTINUED;
842
		else if (signal->group_stop_count)
843 844 845
			why |= SIGNAL_CLD_STOPPED;

		if (why) {
846
			/*
847
			 * The first thread which returns from do_signal_stop()
848 849 850
			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
			 * notify its parent. See get_signal_to_deliver().
			 */
851
			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
852 853
			signal->group_stop_count = 0;
			signal->group_exit_code = 0;
L
Linus Torvalds 已提交
854 855
		}
	}
856

857
	return !sig_ignored(p, sig, force);
L
Linus Torvalds 已提交
858 859
}

860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880
/*
 * 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);
}

881
static void complete_signal(int sig, struct task_struct *p, int group)
882 883 884 885 886 887 888 889 890 891 892 893
{
	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;
894
	else if (!group || thread_group_empty(p))
895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921
		/*
		 * 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.
	 */
922 923
	if (sig_fatal(p, sig) &&
	    !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
924
	    !sigismember(&t->real_blocked, sig) &&
T
Tejun Heo 已提交
925
	    (sig == SIGKILL || !t->ptrace)) {
926 927 928 929 930 931 932 933 934 935 936 937 938 939 940
		/*
		 * 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 {
941
				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
942 943 944 945 946 947 948 949 950 951 952 953 954 955 956
				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;
}

957 958 959 960 961
static inline int legacy_queue(struct sigpending *signals, int sig)
{
	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
}

962 963 964 965 966 967 968 969 970
#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;

971 972 973 974
	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();
975 976 977 978 979 980 981 982
}
#else
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
{
	return;
}
#endif

983 984
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
985
{
986
	struct sigpending *pending;
987
	struct sigqueue *q;
988
	int override_rlimit;
989
	int ret = 0, result;
990

991
	assert_spin_locked(&t->sighand->siglock);
992

993
	result = TRACE_SIGNAL_IGNORED;
994 995
	if (!prepare_signal(sig, t,
			from_ancestor_ns || (info == SEND_SIG_FORCED)))
996
		goto ret;
997 998

	pending = group ? &t->signal->shared_pending : &t->pending;
999 1000 1001 1002 1003
	/*
	 * 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.
	 */
1004
	result = TRACE_SIGNAL_ALREADY_PENDING;
1005
	if (legacy_queue(pending, sig))
1006 1007 1008
		goto ret;

	result = TRACE_SIGNAL_DELIVERED;
L
Linus Torvalds 已提交
1009 1010 1011 1012
	/*
	 * fast-pathed signals for kernel-internal things like SIGSTOP
	 * or SIGKILL.
	 */
1013
	if (info == SEND_SIG_FORCED)
L
Linus Torvalds 已提交
1014 1015
		goto out_set;

1016 1017 1018 1019 1020 1021 1022 1023 1024
	/*
	 * 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.
	 */
1025 1026 1027 1028 1029
	if (sig < SIGRTMIN)
		override_rlimit = (is_si_special(info) || info->si_code >= 0);
	else
		override_rlimit = 0;

1030
	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1031
		override_rlimit);
L
Linus Torvalds 已提交
1032
	if (q) {
1033
		list_add_tail(&q->list, &pending->list);
L
Linus Torvalds 已提交
1034
		switch ((unsigned long) info) {
1035
		case (unsigned long) SEND_SIG_NOINFO:
L
Linus Torvalds 已提交
1036 1037 1038
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_USER;
1039
			q->info.si_pid = task_tgid_nr_ns(current,
1040
							task_active_pid_ns(t));
1041
			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1042
			break;
1043
		case (unsigned long) SEND_SIG_PRIV:
L
Linus Torvalds 已提交
1044 1045 1046 1047 1048 1049 1050 1051
			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);
1052 1053
			if (from_ancestor_ns)
				q->info.si_pid = 0;
L
Linus Torvalds 已提交
1054 1055
			break;
		}
1056 1057 1058

		userns_fixup_signal_uid(&q->info, t);

1059
	} else if (!is_si_special(info)) {
1060 1061 1062 1063 1064 1065
		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().
			 */
1066 1067 1068
			result = TRACE_SIGNAL_OVERFLOW_FAIL;
			ret = -EAGAIN;
			goto ret;
1069 1070 1071 1072 1073
		} else {
			/*
			 * This is a silent loss of information.  We still
			 * send the signal, but the *info bits are lost.
			 */
1074
			result = TRACE_SIGNAL_LOSE_INFO;
1075
		}
L
Linus Torvalds 已提交
1076 1077 1078
	}

out_set:
1079
	signalfd_notify(t, sig);
1080
	sigaddset(&pending->signal, sig);
1081
	complete_signal(sig, t, group);
1082 1083 1084
ret:
	trace_signal_generate(sig, info, t, group, result);
	return ret;
L
Linus Torvalds 已提交
1085 1086
}

1087 1088 1089
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
			int group)
{
1090 1091 1092
	int from_ancestor_ns = 0;

#ifdef CONFIG_PID_NS
1093 1094
	from_ancestor_ns = si_fromuser(info) &&
			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1095 1096 1097
#endif

	return __send_signal(sig, info, t, group, from_ancestor_ns);
1098 1099
}

1100
static void print_fatal_signal(int signr)
I
Ingo Molnar 已提交
1101
{
1102
	struct pt_regs *regs = signal_pt_regs();
1103
	pr_info("potentially unexpected fatal signal %d.\n", signr);
I
Ingo Molnar 已提交
1104

A
Al Viro 已提交
1105
#if defined(__i386__) && !defined(__arch_um__)
1106
	pr_info("code at %08lx: ", regs->ip);
I
Ingo Molnar 已提交
1107 1108 1109 1110 1111
	{
		int i;
		for (i = 0; i < 16; i++) {
			unsigned char insn;

1112 1113
			if (get_user(insn, (unsigned char *)(regs->ip + i)))
				break;
1114
			pr_cont("%02x ", insn);
I
Ingo Molnar 已提交
1115 1116
		}
	}
1117
	pr_cont("\n");
I
Ingo Molnar 已提交
1118
#endif
1119
	preempt_disable();
I
Ingo Molnar 已提交
1120
	show_regs(regs);
1121
	preempt_enable();
I
Ingo Molnar 已提交
1122 1123 1124 1125 1126 1127 1128 1129 1130 1131
}

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
1132

1133 1134 1135 1136 1137 1138
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
1139 1140 1141
static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
1142
	return send_signal(sig, info, t, 0);
L
Linus Torvalds 已提交
1143 1144
}

1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158
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
1159 1160 1161
/*
 * Force a signal that the process can't ignore: if necessary
 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1162 1163 1164 1165 1166
 *
 * 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.
 *
1167 1168
 * 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
1169 1170 1171 1172 1173
 */
int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
	unsigned long int flags;
1174 1175
	int ret, blocked, ignored;
	struct k_sigaction *action;
L
Linus Torvalds 已提交
1176 1177

	spin_lock_irqsave(&t->sighand->siglock, flags);
1178 1179 1180 1181 1182 1183 1184
	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
1185
			recalc_sigpending_and_wake(t);
1186
		}
L
Linus Torvalds 已提交
1187
	}
1188 1189
	if (action->sa.sa_handler == SIG_DFL)
		t->signal->flags &= ~SIGNAL_UNKILLABLE;
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1190 1191 1192 1193 1194 1195 1196 1197 1198
	ret = specific_send_sig_info(sig, info, t);
	spin_unlock_irqrestore(&t->sighand->siglock, flags);

	return ret;
}

/*
 * Nuke all other threads in the group.
 */
1199
int zap_other_threads(struct task_struct *p)
L
Linus Torvalds 已提交
1200
{
1201 1202
	struct task_struct *t = p;
	int count = 0;
L
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1203 1204 1205

	p->signal->group_stop_count = 0;

1206
	while_each_thread(p, t) {
1207
		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1208 1209 1210
		count++;

		/* Don't bother with already dead threads */
L
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1211 1212 1213 1214 1215
		if (t->exit_state)
			continue;
		sigaddset(&t->pending.signal, SIGKILL);
		signal_wake_up(t, 1);
	}
1216 1217

	return count;
L
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1218 1219
}

1220 1221
struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
					   unsigned long *flags)
1222 1223 1224 1225
{
	struct sighand_struct *sighand;

	for (;;) {
1226 1227 1228 1229
		/*
		 * Disable interrupts early to avoid deadlocks.
		 * See rcu_read_unlock() comment header for details.
		 */
1230 1231
		local_irq_save(*flags);
		rcu_read_lock();
1232
		sighand = rcu_dereference(tsk->sighand);
1233 1234 1235
		if (unlikely(sighand == NULL)) {
			rcu_read_unlock();
			local_irq_restore(*flags);
1236
			break;
1237
		}
1238 1239
		/*
		 * This sighand can be already freed and even reused, but
1240
		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1241 1242 1243 1244 1245 1246 1247 1248
		 * 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.
		 */
1249 1250 1251
		spin_lock(&sighand->siglock);
		if (likely(sighand == tsk->sighand)) {
			rcu_read_unlock();
1252
			break;
1253 1254 1255 1256
		}
		spin_unlock(&sighand->siglock);
		rcu_read_unlock();
		local_irq_restore(*flags);
1257 1258 1259 1260 1261
	}

	return sighand;
}

1262 1263 1264
/*
 * send signal info to all the members of a group
 */
L
Linus Torvalds 已提交
1265 1266
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
1267 1268 1269 1270 1271
	int ret;

	rcu_read_lock();
	ret = check_kill_permission(sig, info, p);
	rcu_read_unlock();
1272

1273 1274
	if (!ret && sig)
		ret = do_send_sig_info(sig, info, p, true);
L
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1275 1276 1277 1278 1279

	return ret;
}

/*
1280
 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
L
Linus Torvalds 已提交
1281
 * control characters do (^C, ^Z etc)
1282
 * - the caller must hold at least a readlock on tasklist_lock
L
Linus Torvalds 已提交
1283
 */
1284
int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
L
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1285 1286 1287 1288 1289 1290
{
	struct task_struct *p = NULL;
	int retval, success;

	success = 0;
	retval = -ESRCH;
1291
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
L
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1292 1293 1294
		int err = group_send_sig_info(sig, info, p);
		success |= !err;
		retval = err;
1295
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
L
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	return success ? 0 : retval;
}

1299
int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
L
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1300
{
1301
	int error = -ESRCH;
L
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1302 1303
	struct task_struct *p;

1304 1305 1306 1307 1308 1309 1310 1311
	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;
1312

1313 1314 1315 1316 1317 1318
		/*
		 * 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
1319 1320
}

1321
static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1322 1323 1324
{
	int error;
	rcu_read_lock();
1325
	error = kill_pid_info(sig, info, find_vpid(pid));
1326 1327 1328 1329
	rcu_read_unlock();
	return error;
}

1330 1331 1332 1333
static int kill_as_cred_perm(const struct cred *cred,
			     struct task_struct *target)
{
	const struct cred *pcred = __task_cred(target);
1334 1335
	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))
1336 1337 1338 1339
		return 0;
	return 1;
}

1340
/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1341 1342
int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
			 const struct cred *cred, u32 secid)
1343 1344 1345
{
	int ret = -EINVAL;
	struct task_struct *p;
1346
	unsigned long flags;
1347 1348 1349 1350

	if (!valid_signal(sig))
		return ret;

1351
	rcu_read_lock();
1352
	p = pid_task(pid, PIDTYPE_PID);
1353 1354 1355 1356
	if (!p) {
		ret = -ESRCH;
		goto out_unlock;
	}
1357
	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1358 1359 1360
		ret = -EPERM;
		goto out_unlock;
	}
1361 1362 1363
	ret = security_task_kill(p, info, sig, secid);
	if (ret)
		goto out_unlock;
1364 1365 1366 1367 1368 1369 1370

	if (sig) {
		if (lock_task_sighand(p, &flags)) {
			ret = __send_signal(sig, info, p, 1, 0);
			unlock_task_sighand(p, &flags);
		} else
			ret = -ESRCH;
1371 1372
	}
out_unlock:
1373
	rcu_read_unlock();
1374 1375
	return ret;
}
1376
EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
L
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1377 1378 1379 1380 1381 1382 1383 1384

/*
 * 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.
 */

1385
static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
L
Linus Torvalds 已提交
1386
{
1387
	int ret;
1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400

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

	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
1401 1402 1403 1404
		int retval = 0, count = 0;
		struct task_struct * p;

		for_each_process(p) {
1405 1406
			if (task_pid_vnr(p) > 1 &&
					!same_thread_group(p, current)) {
L
Linus Torvalds 已提交
1407 1408 1409 1410 1411 1412
				int err = group_send_sig_info(sig, info, p);
				++count;
				if (err != -EPERM)
					retval = err;
			}
		}
1413
		ret = count ? retval : -ESRCH;
L
Linus Torvalds 已提交
1414
	}
1415 1416
	read_unlock(&tasklist_lock);

1417
	return ret;
L
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1418 1419 1420 1421 1422 1423
}

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

1424
int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
L
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1425 1426 1427 1428 1429
{
	/*
	 * Make sure legacy kernel users don't send in bad values
	 * (normal paths check this in check_kill_permission).
	 */
1430
	if (!valid_signal(sig))
L
Linus Torvalds 已提交
1431 1432
		return -EINVAL;

1433
	return do_send_sig_info(sig, info, p, false);
L
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1434 1435
}

1436 1437 1438
#define __si_special(priv) \
	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)

L
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1439 1440 1441
int
send_sig(int sig, struct task_struct *p, int priv)
{
1442
	return send_sig_info(sig, __si_special(priv), p);
L
Linus Torvalds 已提交
1443 1444 1445 1446 1447
}

void
force_sig(int sig, struct task_struct *p)
{
1448
	force_sig_info(sig, SEND_SIG_PRIV, p);
L
Linus Torvalds 已提交
1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469
}

/*
 * 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;
}

1470 1471
int kill_pgrp(struct pid *pid, int sig, int priv)
{
1472 1473 1474 1475 1476 1477 1478
	int ret;

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

	return ret;
1479 1480 1481 1482 1483 1484 1485 1486 1487
}
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
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1488 1489 1490 1491
/*
 * 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
1492
 * expirations or I/O completions".  In the case of POSIX Timers
L
Linus Torvalds 已提交
1493 1494 1495 1496 1497 1498
 * 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)
{
1499
	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
L
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1500

1501
	if (q)
L
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1502
		q->flags |= SIGQUEUE_PREALLOC;
1503 1504

	return q;
L
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1505 1506 1507 1508 1509
}

void sigqueue_free(struct sigqueue *q)
{
	unsigned long flags;
1510 1511
	spinlock_t *lock = &current->sighand->siglock;

L
Linus Torvalds 已提交
1512 1513
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
	/*
1514 1515
	 * We must hold ->siglock while testing q->list
	 * to serialize with collect_signal() or with
1516
	 * __exit_signal()->flush_sigqueue().
L
Linus Torvalds 已提交
1517
	 */
1518
	spin_lock_irqsave(lock, flags);
1519 1520 1521 1522 1523
	q->flags &= ~SIGQUEUE_PREALLOC;
	/*
	 * If it is queued it will be freed when dequeued,
	 * like the "regular" sigqueue.
	 */
1524
	if (!list_empty(&q->list))
1525
		q = NULL;
1526 1527
	spin_unlock_irqrestore(lock, flags);

1528 1529
	if (q)
		__sigqueue_free(q);
L
Linus Torvalds 已提交
1530 1531
}

1532
int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1533
{
1534
	int sig = q->info.si_signo;
1535
	struct sigpending *pending;
1536
	unsigned long flags;
1537
	int ret, result;
1538

1539
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1540 1541 1542 1543 1544

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

1545
	ret = 1; /* the signal is ignored */
1546
	result = TRACE_SIGNAL_IGNORED;
1547
	if (!prepare_signal(sig, t, false))
1548 1549 1550
		goto out;

	ret = 0;
1551 1552 1553 1554 1555 1556 1557
	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++;
1558
		result = TRACE_SIGNAL_ALREADY_PENDING;
1559
		goto out;
1560
	}
1561
	q->info.si_overrun = 0;
1562 1563

	signalfd_notify(t, sig);
1564
	pending = group ? &t->signal->shared_pending : &t->pending;
1565 1566
	list_add_tail(&q->list, &pending->list);
	sigaddset(&pending->signal, sig);
1567
	complete_signal(sig, t, group);
1568
	result = TRACE_SIGNAL_DELIVERED;
1569
out:
1570
	trace_signal_generate(sig, &q->info, t, group, result);
1571 1572 1573
	unlock_task_sighand(t, &flags);
ret:
	return ret;
1574 1575
}

L
Linus Torvalds 已提交
1576 1577 1578
/*
 * 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
1579
 *
1580 1581
 * Returns true if our parent ignored us and so we've switched to
 * self-reaping.
L
Linus Torvalds 已提交
1582
 */
1583
bool do_notify_parent(struct task_struct *tsk, int sig)
L
Linus Torvalds 已提交
1584 1585 1586 1587
{
	struct siginfo info;
	unsigned long flags;
	struct sighand_struct *psig;
1588
	bool autoreap = false;
1589
	u64 utime, stime;
L
Linus Torvalds 已提交
1590 1591 1592 1593

	BUG_ON(sig == -1);

 	/* do_notify_parent_cldstop should have been called instead.  */
M
Matthew Wilcox 已提交
1594
 	BUG_ON(task_is_stopped_or_traced(tsk));
L
Linus Torvalds 已提交
1595

T
Tejun Heo 已提交
1596
	BUG_ON(!tsk->ptrace &&
L
Linus Torvalds 已提交
1597 1598
	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));

1599 1600 1601 1602 1603 1604 1605 1606 1607
	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
1608 1609
	info.si_signo = sig;
	info.si_errno = 0;
1610
	/*
1611 1612
	 * We are under tasklist_lock here so our parent is tied to
	 * us and cannot change.
1613
	 *
1614 1615
	 * task_active_pid_ns will always return the same pid namespace
	 * until a task passes through release_task.
1616 1617 1618 1619 1620 1621
	 *
	 * 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();
1622
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1623 1624
	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
				       task_uid(tsk));
1625 1626
	rcu_read_unlock();

1627 1628 1629
	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
1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642

	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
1643
	if (!tsk->ptrace && sig == SIGCHLD &&
L
Linus Torvalds 已提交
1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660
	    (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).
		 */
1661
		autoreap = true;
L
Linus Torvalds 已提交
1662
		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1663
			sig = 0;
L
Linus Torvalds 已提交
1664
	}
1665
	if (valid_signal(sig) && sig)
L
Linus Torvalds 已提交
1666 1667 1668
		__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
1669

1670
	return autoreap;
L
Linus Torvalds 已提交
1671 1672
}

1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687
/**
 * 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
1688 1689 1690
{
	struct siginfo info;
	unsigned long flags;
1691
	struct task_struct *parent;
L
Linus Torvalds 已提交
1692
	struct sighand_struct *sighand;
1693
	u64 utime, stime;
L
Linus Torvalds 已提交
1694

1695
	if (for_ptracer) {
1696
		parent = tsk->parent;
1697
	} else {
1698 1699 1700 1701
		tsk = tsk->group_leader;
		parent = tsk->real_parent;
	}

L
Linus Torvalds 已提交
1702 1703
	info.si_signo = SIGCHLD;
	info.si_errno = 0;
1704
	/*
1705
	 * see comment in do_notify_parent() about the following 4 lines
1706 1707
	 */
	rcu_read_lock();
1708
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1709
	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1710 1711
	rcu_read_unlock();

1712 1713 1714
	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
1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742

 	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);
}

1743 1744
static inline int may_ptrace_stop(void)
{
T
Tejun Heo 已提交
1745
	if (!likely(current->ptrace))
1746 1747 1748 1749 1750 1751 1752
		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
1753
	 * ->siglock we must see ->core_state != NULL. Otherwise it
1754
	 * is safe to enter schedule().
1755 1756 1757 1758
	 *
	 * 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.
1759
	 */
1760
	if (unlikely(current->mm->core_state) &&
1761 1762 1763 1764 1765 1766
	    unlikely(current->mm == current->parent->mm))
		return 0;

	return 1;
}

R
Roland McGrath 已提交
1767
/*
1768
 * Return non-zero if there is a SIGKILL that should be waking us up.
R
Roland McGrath 已提交
1769 1770 1771 1772
 * Called with the siglock held.
 */
static int sigkill_pending(struct task_struct *tsk)
{
1773 1774
	return	sigismember(&tsk->pending.signal, SIGKILL) ||
		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
R
Roland McGrath 已提交
1775 1776
}

L
Linus Torvalds 已提交
1777 1778 1779 1780 1781 1782 1783 1784
/*
 * 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.
 *
1785 1786
 * 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
1787
 */
T
Tejun Heo 已提交
1788
static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1789 1790
	__releases(&current->sighand->siglock)
	__acquires(&current->sighand->siglock)
L
Linus Torvalds 已提交
1791
{
1792 1793
	bool gstop_done = false;

R
Roland McGrath 已提交
1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808
	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);
1809 1810
		if (sigkill_pending(current))
			return;
R
Roland McGrath 已提交
1811 1812
	}

L
Linus Torvalds 已提交
1813
	/*
1814 1815 1816 1817 1818
	 * 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
1819
	 */
1820
	set_current_state(TASK_TRACED);
L
Linus Torvalds 已提交
1821 1822 1823 1824

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

1825
	/*
1826 1827
	 * If @why is CLD_STOPPED, we're trapping to participate in a group
	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1828 1829 1830
	 * 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.
1831
	 */
1832
	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1833
		gstop_done = task_participate_group_stop(current);
1834

1835
	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1836
	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1837 1838
	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1839

1840
	/* entering a trap, clear TRAPPING */
1841
	task_clear_jobctl_trapping(current);
1842

L
Linus Torvalds 已提交
1843 1844
	spin_unlock_irq(&current->sighand->siglock);
	read_lock(&tasklist_lock);
1845
	if (may_ptrace_stop()) {
1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856
		/*
		 * 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);
1857
		if (gstop_done && ptrace_reparented(current))
1858 1859
			do_notify_parent_cldstop(current, false, why);

M
Miklos Szeredi 已提交
1860 1861 1862 1863 1864 1865 1866
		/*
		 * 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
1867
		read_unlock(&tasklist_lock);
M
Miklos Szeredi 已提交
1868
		preempt_enable_no_resched();
1869
		freezable_schedule();
L
Linus Torvalds 已提交
1870 1871 1872
	} else {
		/*
		 * By the time we got the lock, our tracer went away.
1873
		 * Don't drop the lock yet, another tracer may come.
1874 1875 1876
		 *
		 * If @gstop_done, the ptracer went away between group stop
		 * completion and here.  During detach, it would have set
1877 1878 1879
		 * 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
1880
		 */
1881 1882 1883
		if (gstop_done)
			do_notify_parent_cldstop(current, false, why);

1884
		/* tasklist protects us from ptrace_freeze_traced() */
1885
		__set_current_state(TASK_RUNNING);
1886 1887
		if (clear_code)
			current->exit_code = 0;
1888
		read_unlock(&tasklist_lock);
L
Linus Torvalds 已提交
1889 1890 1891 1892 1893 1894 1895 1896 1897 1898
	}

	/*
	 * 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
1899 1900 1901
	/* LISTENING can be set only during STOP traps, clear it */
	current->jobctl &= ~JOBCTL_LISTENING;

L
Linus Torvalds 已提交
1902 1903 1904
	/*
	 * Queued signals ignored us while we were stopped for tracing.
	 * So check for any that we should take before resuming user mode.
1905
	 * This sets TIF_SIGPENDING, but never clears it.
L
Linus Torvalds 已提交
1906
	 */
1907
	recalc_sigpending_tsk(current);
L
Linus Torvalds 已提交
1908 1909
}

T
Tejun Heo 已提交
1910
static void ptrace_do_notify(int signr, int exit_code, int why)
L
Linus Torvalds 已提交
1911 1912 1913 1914
{
	siginfo_t info;

	memset(&info, 0, sizeof info);
T
Tejun Heo 已提交
1915
	info.si_signo = signr;
L
Linus Torvalds 已提交
1916
	info.si_code = exit_code;
1917
	info.si_pid = task_pid_vnr(current);
1918
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1919 1920

	/* Let the debugger run.  */
T
Tejun Heo 已提交
1921 1922 1923 1924 1925 1926
	ptrace_stop(exit_code, why, 1, &info);
}

void ptrace_notify(int exit_code)
{
	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1927 1928
	if (unlikely(current->task_works))
		task_work_run();
T
Tejun Heo 已提交
1929

L
Linus Torvalds 已提交
1930
	spin_lock_irq(&current->sighand->siglock);
T
Tejun Heo 已提交
1931
	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
L
Linus Torvalds 已提交
1932 1933 1934
	spin_unlock_irq(&current->sighand->siglock);
}

1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955
/**
 * 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
1956
 */
1957 1958
static bool do_signal_stop(int signr)
	__releases(&current->sighand->siglock)
L
Linus Torvalds 已提交
1959 1960 1961
{
	struct signal_struct *sig = current->signal;

1962
	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1963
		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1964 1965
		struct task_struct *t;

1966 1967
		/* signr will be recorded in task->jobctl for retries */
		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1968

1969
		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1970
		    unlikely(signal_group_exit(sig)))
1971
			return false;
L
Linus Torvalds 已提交
1972
		/*
1973 1974 1975 1976 1977 1978 1979
		 * 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
1980 1981
		 * cause two group stops when !ptraced.  That is why we
		 * also check !task_is_stopped(t) below.
1982 1983 1984 1985 1986 1987 1988 1989
		 *
		 * 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
1990
		 */
1991 1992
		if (!(sig->flags & SIGNAL_STOP_STOPPED))
			sig->group_exit_code = signr;
L
Linus Torvalds 已提交
1993

1994 1995 1996 1997
		sig->group_stop_count = 0;

		if (task_set_jobctl_pending(current, signr | gstop))
			sig->group_stop_count++;
L
Linus Torvalds 已提交
1998

1999 2000
		t = current;
		while_each_thread(current, t) {
L
Linus Torvalds 已提交
2001
			/*
2002 2003 2004
			 * 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
2005
			 */
2006 2007
			if (!task_is_stopped(t) &&
			    task_set_jobctl_pending(t, signr | gstop)) {
2008
				sig->group_stop_count++;
2009 2010 2011 2012
				if (likely(!(t->ptrace & PT_SEIZED)))
					signal_wake_up(t, 0);
				else
					ptrace_trap_notify(t);
2013
			}
2014
		}
L
Linus Torvalds 已提交
2015
	}
2016

T
Tejun Heo 已提交
2017
	if (likely(!current->ptrace)) {
2018
		int notify = 0;
L
Linus Torvalds 已提交
2019

2020 2021 2022 2023 2024 2025 2026 2027
		/*
		 * 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;

2028
		__set_current_state(TASK_STOPPED);
2029 2030
		spin_unlock_irq(&current->sighand->siglock);

2031 2032 2033 2034 2035 2036 2037 2038 2039
		/*
		 * 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.
		 */
2040 2041
		if (notify) {
			read_lock(&tasklist_lock);
2042
			do_notify_parent_cldstop(current, false, notify);
2043 2044 2045 2046
			read_unlock(&tasklist_lock);
		}

		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2047
		freezable_schedule();
2048
		return true;
2049
	} else {
2050 2051 2052 2053 2054 2055
		/*
		 * 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;
2056
	}
2057
}
L
Linus Torvalds 已提交
2058

2059 2060 2061
/**
 * do_jobctl_trap - take care of ptrace jobctl traps
 *
T
Tejun Heo 已提交
2062 2063 2064 2065 2066 2067 2068
 * 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.
2069 2070 2071 2072 2073 2074 2075
 *
 * 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
2076
	struct signal_struct *signal = current->signal;
2077
	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2078

T
Tejun Heo 已提交
2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089
	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;
2090
	}
L
Linus Torvalds 已提交
2091 2092
}

2093
static int ptrace_signal(int signr, siginfo_t *info)
R
Roland McGrath 已提交
2094
{
2095
	ptrace_signal_deliver();
2096 2097 2098 2099 2100 2101 2102 2103 2104 2105
	/*
	 * 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
2106
	ptrace_stop(signr, CLD_TRAPPED, 0, info);
R
Roland McGrath 已提交
2107 2108 2109 2110 2111 2112 2113 2114

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

	current->exit_code = 0;

2115 2116 2117 2118 2119 2120
	/*
	 * 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
2121 2122 2123 2124
	if (signr != info->si_signo) {
		info->si_signo = signr;
		info->si_errno = 0;
		info->si_code = SI_USER;
2125
		rcu_read_lock();
R
Roland McGrath 已提交
2126
		info->si_pid = task_pid_vnr(current->parent);
2127 2128
		info->si_uid = from_kuid_munged(current_user_ns(),
						task_uid(current->parent));
2129
		rcu_read_unlock();
R
Roland McGrath 已提交
2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140
	}

	/* 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;
}

2141
int get_signal(struct ksignal *ksig)
L
Linus Torvalds 已提交
2142
{
2143 2144 2145
	struct sighand_struct *sighand = current->sighand;
	struct signal_struct *signal = current->signal;
	int signr;
L
Linus Torvalds 已提交
2146

2147 2148
	if (unlikely(current->task_works))
		task_work_run();
2149

2150 2151 2152
	if (unlikely(uprobe_deny_signal()))
		return 0;

R
Roland McGrath 已提交
2153
	/*
2154 2155 2156
	 * 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
2157
	 */
2158 2159
	try_to_freeze();

2160
relock:
2161
	spin_lock_irq(&sighand->siglock);
2162 2163 2164 2165 2166
	/*
	 * 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.
	 */
2167
	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2168 2169 2170 2171 2172 2173 2174
		int why;

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

2175
		signal->flags &= ~SIGNAL_CLD_MASK;
2176

2177
		spin_unlock_irq(&sighand->siglock);
R
Roland McGrath 已提交
2178

2179 2180 2181 2182 2183 2184 2185 2186
		/*
		 * 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
2187
		read_lock(&tasklist_lock);
2188 2189
		do_notify_parent_cldstop(current, false, why);

2190 2191 2192
		if (ptrace_reparented(current->group_leader))
			do_notify_parent_cldstop(current->group_leader,
						true, why);
T
Tejun Heo 已提交
2193
		read_unlock(&tasklist_lock);
2194

2195 2196 2197
		goto relock;
	}

L
Linus Torvalds 已提交
2198 2199
	for (;;) {
		struct k_sigaction *ka;
2200

T
Tejun Heo 已提交
2201 2202
		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
		    do_signal_stop(0))
2203
			goto relock;
2204

2205 2206 2207 2208 2209
		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
			do_jobctl_trap();
			spin_unlock_irq(&sighand->siglock);
			goto relock;
		}
L
Linus Torvalds 已提交
2210

2211
		signr = dequeue_signal(current, &current->blocked, &ksig->info);
2212

T
Tejun Heo 已提交
2213 2214
		if (!signr)
			break; /* will return 0 */
2215

2216
		if (unlikely(current->ptrace) && signr != SIGKILL) {
2217
			signr = ptrace_signal(signr, &ksig->info);
T
Tejun Heo 已提交
2218 2219
			if (!signr)
				continue;
L
Linus Torvalds 已提交
2220 2221
		}

T
Tejun Heo 已提交
2222 2223
		ka = &sighand->action[signr-1];

2224
		/* Trace actually delivered signals. */
2225
		trace_signal_deliver(signr, &ksig->info, ka);
2226

L
Linus Torvalds 已提交
2227 2228 2229 2230
		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
			continue;
		if (ka->sa.sa_handler != SIG_DFL) {
			/* Run the handler.  */
2231
			ksig->ka = *ka;
L
Linus Torvalds 已提交
2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244

			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;

2245
		/*
2246
		 * Global init gets no signals it doesn't want.
2247 2248 2249 2250 2251 2252 2253
		 * 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.
2254
		 */
2255
		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2256
				!sig_kernel_only(signr))
L
Linus Torvalds 已提交
2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270
			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) {
2271
				spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2272 2273 2274

				/* signals can be posted during this window */

2275
				if (is_current_pgrp_orphaned())
L
Linus Torvalds 已提交
2276 2277
					goto relock;

2278
				spin_lock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2279 2280
			}

2281
			if (likely(do_signal_stop(ksig->info.si_signo))) {
L
Linus Torvalds 已提交
2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292
				/* It released the siglock.  */
				goto relock;
			}

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

2293
		spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2294 2295 2296 2297 2298

		/*
		 * Anything else is fatal, maybe with a core dump.
		 */
		current->flags |= PF_SIGNALED;
2299

L
Linus Torvalds 已提交
2300
		if (sig_kernel_coredump(signr)) {
2301
			if (print_fatal_signals)
2302
				print_fatal_signal(ksig->info.si_signo);
2303
			proc_coredump_connector(current);
L
Linus Torvalds 已提交
2304 2305 2306 2307 2308 2309 2310 2311
			/*
			 * 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.
			 */
2312
			do_coredump(&ksig->info);
L
Linus Torvalds 已提交
2313 2314 2315 2316 2317
		}

		/*
		 * Death signals, no core dump.
		 */
2318
		do_group_exit(ksig->info.si_signo);
L
Linus Torvalds 已提交
2319 2320
		/* NOTREACHED */
	}
2321
	spin_unlock_irq(&sighand->siglock);
2322 2323 2324

	ksig->sig = signr;
	return ksig->sig > 0;
L
Linus Torvalds 已提交
2325 2326
}

2327
/**
A
Al Viro 已提交
2328
 * signal_delivered - 
R
Richard Weinberger 已提交
2329
 * @ksig:		kernel signal struct
A
Al Viro 已提交
2330
 * @stepping:		nonzero if debugger single-step or block-step in use
2331
 *
2332
 * This function should be called when a signal has successfully been
R
Richard Weinberger 已提交
2333
 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
A
Al Viro 已提交
2334
 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
R
Richard Weinberger 已提交
2335
 * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2336
 */
R
Richard Weinberger 已提交
2337
static void signal_delivered(struct ksignal *ksig, int stepping)
2338 2339 2340
{
	sigset_t blocked;

2341 2342 2343 2344 2345 2346
	/* 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
2347 2348 2349
	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
		sigaddset(&blocked, ksig->sig);
2350
	set_current_blocked(&blocked);
2351
	tracehook_signal_handler(stepping);
2352 2353
}

A
Al Viro 已提交
2354 2355 2356 2357 2358
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
2359
		signal_delivered(ksig, stepping);
A
Al Viro 已提交
2360 2361
}

2362 2363
/*
 * It could be that complete_signal() picked us to notify about the
2364 2365
 * group-wide signal. Other threads should be notified now to take
 * the shared signals in @which since we will not.
2366
 */
2367
static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2368
{
2369
	sigset_t retarget;
2370 2371
	struct task_struct *t;

2372 2373 2374 2375
	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
	if (sigisemptyset(&retarget))
		return;

2376 2377
	t = tsk;
	while_each_thread(tsk, t) {
2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390
		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;
2391 2392 2393
	}
}

O
Oleg Nesterov 已提交
2394 2395 2396
void exit_signals(struct task_struct *tsk)
{
	int group_stop = 0;
2397
	sigset_t unblocked;
O
Oleg Nesterov 已提交
2398

2399 2400 2401 2402
	/*
	 * @tsk is about to have PF_EXITING set - lock out users which
	 * expect stable threadgroup.
	 */
2403
	cgroup_threadgroup_change_begin(tsk);
2404

2405 2406
	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
		tsk->flags |= PF_EXITING;
2407
		cgroup_threadgroup_change_end(tsk);
2408
		return;
O
Oleg Nesterov 已提交
2409 2410
	}

2411
	spin_lock_irq(&tsk->sighand->siglock);
O
Oleg Nesterov 已提交
2412 2413 2414 2415 2416
	/*
	 * From now this task is not visible for group-wide signals,
	 * see wants_signal(), do_signal_stop().
	 */
	tsk->flags |= PF_EXITING;
2417

2418
	cgroup_threadgroup_change_end(tsk);
2419

2420 2421 2422
	if (!signal_pending(tsk))
		goto out;

2423 2424 2425
	unblocked = tsk->blocked;
	signotset(&unblocked);
	retarget_shared_pending(tsk, &unblocked);
2426

2427
	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2428
	    task_participate_group_stop(tsk))
T
Tejun Heo 已提交
2429
		group_stop = CLD_STOPPED;
2430
out:
O
Oleg Nesterov 已提交
2431 2432
	spin_unlock_irq(&tsk->sighand->siglock);

2433 2434 2435 2436
	/*
	 * If group stop has completed, deliver the notification.  This
	 * should always go to the real parent of the group leader.
	 */
2437
	if (unlikely(group_stop)) {
O
Oleg Nesterov 已提交
2438
		read_lock(&tasklist_lock);
2439
		do_notify_parent_cldstop(tsk, false, group_stop);
O
Oleg Nesterov 已提交
2440 2441 2442 2443
		read_unlock(&tasklist_lock);
	}
}

L
Linus Torvalds 已提交
2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455
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.
 */

2456 2457 2458
/**
 *  sys_restart_syscall - restart a system call
 */
2459
SYSCALL_DEFINE0(restart_syscall)
L
Linus Torvalds 已提交
2460
{
2461
	struct restart_block *restart = &current->restart_block;
L
Linus Torvalds 已提交
2462 2463 2464 2465 2466 2467 2468 2469
	return restart->fn(restart);
}

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

2470 2471 2472 2473 2474
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. */
2475
		sigandnsets(&newblocked, newset, &current->blocked);
2476 2477 2478 2479 2480 2481
		retarget_shared_pending(tsk, &newblocked);
	}
	tsk->blocked = *newset;
	recalc_sigpending();
}

2482 2483 2484 2485 2486 2487
/**
 * 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
2488
 */
2489 2490 2491
void set_current_blocked(sigset_t *newset)
{
	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2492
	__set_current_blocked(newset);
2493 2494 2495
}

void __set_current_blocked(const sigset_t *newset)
2496 2497 2498
{
	struct task_struct *tsk = current;

2499 2500 2501 2502 2503 2504 2505
	/*
	 * 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;

2506
	spin_lock_irq(&tsk->sighand->siglock);
2507
	__set_task_blocked(tsk, newset);
2508 2509
	spin_unlock_irq(&tsk->sighand->siglock);
}
L
Linus Torvalds 已提交
2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520

/*
 * 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)
{
2521 2522
	struct task_struct *tsk = current;
	sigset_t newset;
L
Linus Torvalds 已提交
2523

2524
	/* Lockless, only current can change ->blocked, never from irq */
2525
	if (oldset)
2526
		*oldset = tsk->blocked;
2527

L
Linus Torvalds 已提交
2528 2529
	switch (how) {
	case SIG_BLOCK:
2530
		sigorsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2531 2532
		break;
	case SIG_UNBLOCK:
2533
		sigandnsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2534 2535
		break;
	case SIG_SETMASK:
2536
		newset = *set;
L
Linus Torvalds 已提交
2537 2538
		break;
	default:
2539
		return -EINVAL;
L
Linus Torvalds 已提交
2540
	}
2541

2542
	__set_current_blocked(&newset);
2543
	return 0;
L
Linus Torvalds 已提交
2544 2545
}

2546 2547 2548
/**
 *  sys_rt_sigprocmask - change the list of currently blocked signals
 *  @how: whether to add, remove, or set signals
R
Randy Dunlap 已提交
2549
 *  @nset: stores pending signals
2550 2551 2552
 *  @oset: previous value of signal mask if non-null
 *  @sigsetsize: size of sigset_t type
 */
2553
SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2554
		sigset_t __user *, oset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2555 2556
{
	sigset_t old_set, new_set;
2557
	int error;
L
Linus Torvalds 已提交
2558 2559 2560

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
2561
		return -EINVAL;
L
Linus Torvalds 已提交
2562

2563 2564 2565 2566 2567
	old_set = current->blocked;

	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2568 2569
		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

2570
		error = sigprocmask(how, &new_set, NULL);
L
Linus Torvalds 已提交
2571
		if (error)
2572 2573
			return error;
	}
L
Linus Torvalds 已提交
2574

2575 2576 2577
	if (oset) {
		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2578
	}
2579 2580

	return 0;
L
Linus Torvalds 已提交
2581 2582
}

A
Al Viro 已提交
2583 2584 2585
#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
2586
{
A
Al Viro 已提交
2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610
#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
2611
		if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
A
Al Viro 已提交
2612 2613 2614 2615 2616 2617 2618 2619 2620
			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
2621

A
Al Viro 已提交
2622
static int do_sigpending(void *set, unsigned long sigsetsize)
L
Linus Torvalds 已提交
2623 2624
{
	if (sigsetsize > sizeof(sigset_t))
A
Al Viro 已提交
2625
		return -EINVAL;
L
Linus Torvalds 已提交
2626 2627

	spin_lock_irq(&current->sighand->siglock);
A
Al Viro 已提交
2628
	sigorsets(set, &current->pending.signal,
L
Linus Torvalds 已提交
2629 2630 2631 2632
		  &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
2633 2634
	sigandsets(set, &current->blocked, set);
	return 0;
2635
}
L
Linus Torvalds 已提交
2636

2637 2638 2639
/**
 *  sys_rt_sigpending - examine a pending signal that has been raised
 *			while blocked
2640
 *  @uset: stores pending signals
2641 2642
 *  @sigsetsize: size of sigset_t type or larger
 */
A
Al Viro 已提交
2643
SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2644
{
A
Al Viro 已提交
2645 2646 2647 2648 2649 2650 2651 2652 2653 2654
	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
2655
{
A
Al Viro 已提交
2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669
#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
2670
}
A
Al Viro 已提交
2671
#endif
L
Linus Torvalds 已提交
2672 2673 2674

#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER

A
Al Viro 已提交
2675
int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
L
Linus Torvalds 已提交
2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686
{
	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.
2687 2688
	 * Please remember to update the signalfd_copyinfo() function
	 * inside fs/signalfd.c too, in case siginfo_t changes.
L
Linus Torvalds 已提交
2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713
	 * 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
2714 2715
#endif
#ifdef BUS_MCEERR_AO
2716
		/*
A
Andi Kleen 已提交
2717
		 * Other callers might not initialize the si_lsb field,
2718
		 * so check explicitly for the right codes here.
A
Andi Kleen 已提交
2719
		 */
2720 2721
		if (from->si_signo == SIGBUS &&
		    (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
A
Andi Kleen 已提交
2722
			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2723 2724
#endif
#ifdef SEGV_BNDERR
2725 2726 2727 2728
		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);
		}
2729 2730 2731 2732
#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
2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747
#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;
2748 2749 2750 2751 2752 2753 2754
#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
L
Linus Torvalds 已提交
2755 2756 2757 2758 2759 2760 2761 2762 2763 2764
	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

2765 2766 2767 2768 2769 2770 2771
/**
 *  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
 */
int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
2772
		    const struct timespec *ts)
2773
{
T
Thomas Gleixner 已提交
2774
	ktime_t *to = NULL, timeout = KTIME_MAX;
2775 2776
	struct task_struct *tsk = current;
	sigset_t mask = *which;
2777
	int sig, ret = 0;
2778 2779 2780 2781

	if (ts) {
		if (!timespec_valid(ts))
			return -EINVAL;
2782 2783
		timeout = timespec_to_ktime(*ts);
		to = &timeout;
2784 2785 2786 2787 2788 2789 2790 2791 2792 2793
	}

	/*
	 * 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
2794
	if (!sig && timeout) {
2795 2796 2797
		/*
		 * None ready, temporarily unblock those we're interested
		 * while we are sleeping in so that we'll be awakened when
2798 2799
		 * they arrive. Unblocking is always fine, we can avoid
		 * set_current_blocked().
2800 2801 2802 2803 2804 2805
		 */
		tsk->real_blocked = tsk->blocked;
		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
		recalc_sigpending();
		spin_unlock_irq(&tsk->sighand->siglock);

2806 2807 2808
		__set_current_state(TASK_INTERRUPTIBLE);
		ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
							 HRTIMER_MODE_REL);
2809
		spin_lock_irq(&tsk->sighand->siglock);
2810
		__set_task_blocked(tsk, &tsk->real_blocked);
2811
		sigemptyset(&tsk->real_blocked);
2812
		sig = dequeue_signal(tsk, &mask, info);
2813 2814 2815 2816 2817
	}
	spin_unlock_irq(&tsk->sighand->siglock);

	if (sig)
		return sig;
2818
	return ret ? -EINTR : -EAGAIN;
2819 2820
}

2821 2822 2823 2824 2825 2826 2827 2828
/**
 *  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
 */
2829 2830 2831
SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
		siginfo_t __user *, uinfo, const struct timespec __user *, uts,
		size_t, sigsetsize)
L
Linus Torvalds 已提交
2832 2833 2834 2835
{
	sigset_t these;
	struct timespec ts;
	siginfo_t info;
2836
	int ret;
L
Linus Torvalds 已提交
2837 2838 2839 2840 2841 2842 2843

	/* 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;
2844

L
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2845 2846 2847 2848 2849
	if (uts) {
		if (copy_from_user(&ts, uts, sizeof(ts)))
			return -EFAULT;
	}

2850
	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
L
Linus Torvalds 已提交
2851

2852 2853 2854
	if (ret > 0 && uinfo) {
		if (copy_siginfo_to_user(uinfo, &info))
			ret = -EFAULT;
L
Linus Torvalds 已提交
2855 2856 2857 2858 2859
	}

	return ret;
}

2860 2861 2862 2863 2864
/**
 *  sys_kill - send a signal to a process
 *  @pid: the PID of the process
 *  @sig: signal to be sent
 */
2865
SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2866 2867 2868 2869 2870 2871
{
	struct siginfo info;

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_USER;
2872
	info.si_pid = task_tgid_vnr(current);
2873
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
2874 2875 2876 2877

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

T
Thomas Gleixner 已提交
2878 2879
static int
do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
L
Linus Torvalds 已提交
2880 2881
{
	struct task_struct *p;
T
Thomas Gleixner 已提交
2882
	int error = -ESRCH;
L
Linus Torvalds 已提交
2883

2884
	rcu_read_lock();
2885
	p = find_task_by_vpid(pid);
2886
	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
T
Thomas Gleixner 已提交
2887
		error = check_kill_permission(sig, info, p);
L
Linus Torvalds 已提交
2888 2889 2890 2891
		/*
		 * The null signal is a permissions and process existence
		 * probe.  No signal is actually delivered.
		 */
2892 2893 2894 2895 2896 2897 2898 2899 2900
		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
2901 2902
		}
	}
2903
	rcu_read_unlock();
2904

L
Linus Torvalds 已提交
2905 2906 2907
	return error;
}

T
Thomas Gleixner 已提交
2908 2909
static int do_tkill(pid_t tgid, pid_t pid, int sig)
{
2910
	struct siginfo info = {};
T
Thomas Gleixner 已提交
2911 2912 2913 2914 2915

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_TKILL;
	info.si_pid = task_tgid_vnr(current);
2916
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
T
Thomas Gleixner 已提交
2917 2918 2919 2920

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

2921 2922 2923 2924 2925 2926
/**
 *  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
 *
2927
 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
2928 2929 2930
 *  exists but it's not belonging to the target process anymore. This
 *  method solves the problem of threads exiting and PIDs getting reused.
 */
2931
SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2932 2933 2934 2935 2936 2937 2938 2939
{
	/* This is only valid for single tasks */
	if (pid <= 0 || tgid <= 0)
		return -EINVAL;

	return do_tkill(tgid, pid, sig);
}

2940 2941 2942 2943 2944
/**
 *  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
2945 2946
 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
 */
2947
SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2948 2949 2950 2951 2952
{
	/* This is only valid for single tasks */
	if (pid <= 0)
		return -EINVAL;

2953
	return do_tkill(0, pid, sig);
L
Linus Torvalds 已提交
2954 2955
}

A
Al Viro 已提交
2956 2957 2958 2959 2960
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.
	 */
2961
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2962
	    (task_pid_vnr(current) != pid))
A
Al Viro 已提交
2963
		return -EPERM;
2964

A
Al Viro 已提交
2965 2966 2967 2968 2969 2970
	info->si_signo = sig;

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

2971 2972 2973 2974 2975 2976
/**
 *  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
 */
2977 2978
SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
		siginfo_t __user *, uinfo)
L
Linus Torvalds 已提交
2979 2980 2981 2982
{
	siginfo_t info;
	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
		return -EFAULT;
A
Al Viro 已提交
2983 2984
	return do_rt_sigqueueinfo(pid, sig, &info);
}
L
Linus Torvalds 已提交
2985

A
Al Viro 已提交
2986 2987 2988 2989 2990 2991
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
2992
	siginfo_t info = {};
A
Al Viro 已提交
2993 2994 2995 2996
	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
2997
}
A
Al Viro 已提交
2998
#endif
L
Linus Torvalds 已提交
2999

3000
static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3001 3002 3003 3004 3005 3006
{
	/* 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.
3007 3008
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
3009 3010
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
	    (task_pid_vnr(current) != pid))
3011
		return -EPERM;
3012

3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028
	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);
}

3029 3030 3031 3032 3033 3034 3035
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
			compat_pid_t, tgid,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
3036
	siginfo_t info = {};
3037 3038 3039 3040 3041 3042 3043

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

3044
/*
3045
 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3046
 */
3047
void kernel_sigaction(int sig, __sighandler_t action)
3048
{
3049
	spin_lock_irq(&current->sighand->siglock);
3050 3051 3052
	current->sighand->action[sig - 1].sa.sa_handler = action;
	if (action == SIG_IGN) {
		sigset_t mask;
3053

3054 3055
		sigemptyset(&mask);
		sigaddset(&mask, sig);
3056

3057 3058 3059 3060
		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
		flush_sigqueue_mask(&mask, &current->pending);
		recalc_sigpending();
	}
3061 3062
	spin_unlock_irq(&current->sighand->siglock);
}
3063
EXPORT_SYMBOL(kernel_sigaction);
3064

3065 3066 3067 3068 3069
void __weak sigaction_compat_abi(struct k_sigaction *act,
		struct k_sigaction *oact)
{
}

3070
int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
L
Linus Torvalds 已提交
3071
{
3072
	struct task_struct *p = current, *t;
L
Linus Torvalds 已提交
3073
	struct k_sigaction *k;
3074
	sigset_t mask;
L
Linus Torvalds 已提交
3075

3076
	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
L
Linus Torvalds 已提交
3077 3078
		return -EINVAL;

3079
	k = &p->sighand->action[sig-1];
L
Linus Torvalds 已提交
3080

3081
	spin_lock_irq(&p->sighand->siglock);
L
Linus Torvalds 已提交
3082 3083 3084
	if (oact)
		*oact = *k;

3085 3086
	sigaction_compat_abi(act, oact);

L
Linus Torvalds 已提交
3087
	if (act) {
3088 3089
		sigdelsetmask(&act->sa.sa_mask,
			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3090
		*k = *act;
L
Linus Torvalds 已提交
3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101
		/*
		 * 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"
		 */
3102
		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3103 3104
			sigemptyset(&mask);
			sigaddset(&mask, sig);
3105 3106
			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
			for_each_thread(p, t)
3107
				flush_sigqueue_mask(&mask, &t->pending);
L
Linus Torvalds 已提交
3108 3109 3110
		}
	}

3111
	spin_unlock_irq(&p->sighand->siglock);
L
Linus Torvalds 已提交
3112 3113 3114
	return 0;
}

3115
static int
L
Linus Torvalds 已提交
3116 3117 3118 3119 3120
do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
{
	stack_t oss;
	int error;

3121 3122
	oss.ss_sp = (void __user *) current->sas_ss_sp;
	oss.ss_size = current->sas_ss_size;
3123 3124
	oss.ss_flags = sas_ss_flags(sp) |
		(current->sas_ss_flags & SS_FLAG_BITS);
L
Linus Torvalds 已提交
3125 3126 3127 3128

	if (uss) {
		void __user *ss_sp;
		size_t ss_size;
3129 3130
		unsigned ss_flags;
		int ss_mode;
L
Linus Torvalds 已提交
3131 3132

		error = -EFAULT;
L
Linus Torvalds 已提交
3133 3134 3135 3136 3137 3138
		if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
			goto out;
		error = __get_user(ss_sp, &uss->ss_sp) |
			__get_user(ss_flags, &uss->ss_flags) |
			__get_user(ss_size, &uss->ss_size);
		if (error)
L
Linus Torvalds 已提交
3139 3140 3141 3142 3143 3144
			goto out;

		error = -EPERM;
		if (on_sig_stack(sp))
			goto out;

3145
		ss_mode = ss_flags & ~SS_FLAG_BITS;
L
Linus Torvalds 已提交
3146
		error = -EINVAL;
3147 3148
		if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
				ss_mode != 0)
L
Linus Torvalds 已提交
3149 3150
			goto out;

3151
		if (ss_mode == SS_DISABLE) {
L
Linus Torvalds 已提交
3152 3153 3154 3155 3156 3157 3158 3159 3160 3161
			ss_size = 0;
			ss_sp = NULL;
		} else {
			error = -ENOMEM;
			if (ss_size < MINSIGSTKSZ)
				goto out;
		}

		current->sas_ss_sp = (unsigned long) ss_sp;
		current->sas_ss_size = ss_size;
3162
		current->sas_ss_flags = ss_flags;
L
Linus Torvalds 已提交
3163 3164
	}

3165
	error = 0;
L
Linus Torvalds 已提交
3166 3167
	if (uoss) {
		error = -EFAULT;
3168
		if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
L
Linus Torvalds 已提交
3169
			goto out;
3170 3171 3172
		error = __put_user(oss.ss_sp, &uoss->ss_sp) |
			__put_user(oss.ss_size, &uoss->ss_size) |
			__put_user(oss.ss_flags, &uoss->ss_flags);
L
Linus Torvalds 已提交
3173 3174 3175 3176 3177
	}

out:
	return error;
}
3178 3179 3180 3181
SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
{
	return do_sigaltstack(uss, uoss, current_user_stack_pointer());
}
L
Linus Torvalds 已提交
3182

A
Al Viro 已提交
3183 3184 3185 3186 3187 3188 3189
int restore_altstack(const stack_t __user *uss)
{
	int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
	/* squash all but EFAULT for now */
	return err == -EFAULT ? err : 0;
}

3190 3191 3192
int __save_altstack(stack_t __user *uss, unsigned long sp)
{
	struct task_struct *t = current;
3193 3194
	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3195
		__put_user(t->sas_ss_size, &uss->ss_size);
3196 3197 3198 3199 3200
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3201 3202
}

A
Al Viro 已提交
3203
#ifdef CONFIG_COMPAT
3204 3205 3206
COMPAT_SYSCALL_DEFINE2(sigaltstack,
			const compat_stack_t __user *, uss_ptr,
			compat_stack_t __user *, uoss_ptr)
A
Al Viro 已提交
3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243
{
	stack_t uss, uoss;
	int ret;
	mm_segment_t seg;

	if (uss_ptr) {
		compat_stack_t uss32;

		memset(&uss, 0, sizeof(stack_t));
		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;
	}
	seg = get_fs();
	set_fs(KERNEL_DS);
	ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
			     (stack_t __force __user *) &uoss,
			     compat_user_stack_pointer());
	set_fs(seg);
	if (ret >= 0 && uoss_ptr)  {
		if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
		    __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
		    __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
		    __put_user(uoss.ss_size, &uoss_ptr->ss_size))
			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;
}
3244 3245 3246

int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
{
3247
	int err;
3248
	struct task_struct *t = current;
3249 3250 3251
	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
			 &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3252
		__put_user(t->sas_ss_size, &uss->ss_size);
3253 3254 3255 3256 3257
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3258
}
A
Al Viro 已提交
3259
#endif
L
Linus Torvalds 已提交
3260 3261 3262

#ifdef __ARCH_WANT_SYS_SIGPENDING

3263 3264 3265 3266
/**
 *  sys_sigpending - examine pending signals
 *  @set: where mask of pending signal is returned
 */
3267
SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
L
Linus Torvalds 已提交
3268
{
A
Al Viro 已提交
3269
	return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 
L
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3270 3271 3272 3273 3274
}

#endif

#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3275 3276 3277
/**
 *  sys_sigprocmask - examine and change blocked signals
 *  @how: whether to add, remove, or set signals
3278
 *  @nset: signals to add or remove (if non-null)
3279 3280
 *  @oset: previous value of signal mask if non-null
 *
3281 3282 3283
 * Some platforms have their own version with special arguments;
 * others support only sys_rt_sigprocmask.
 */
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3284

3285
SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3286
		old_sigset_t __user *, oset)
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3287 3288
{
	old_sigset_t old_set, new_set;
3289
	sigset_t new_blocked;
L
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3290

3291
	old_set = current->blocked.sig[0];
L
Linus Torvalds 已提交
3292

3293 3294 3295
	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(*nset)))
			return -EFAULT;
L
Linus Torvalds 已提交
3296

3297
		new_blocked = current->blocked;
L
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3298 3299 3300

		switch (how) {
		case SIG_BLOCK:
3301
			sigaddsetmask(&new_blocked, new_set);
L
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3302 3303
			break;
		case SIG_UNBLOCK:
3304
			sigdelsetmask(&new_blocked, new_set);
L
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3305 3306
			break;
		case SIG_SETMASK:
3307
			new_blocked.sig[0] = new_set;
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3308
			break;
3309 3310
		default:
			return -EINVAL;
L
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3311 3312
		}

3313
		set_current_blocked(&new_blocked);
3314 3315 3316
	}

	if (oset) {
L
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3317
		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3318
			return -EFAULT;
L
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3319
	}
3320 3321

	return 0;
L
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3322 3323 3324
}
#endif /* __ARCH_WANT_SYS_SIGPROCMASK */

3325
#ifndef CONFIG_ODD_RT_SIGACTION
3326 3327 3328
/**
 *  sys_rt_sigaction - alter an action taken by a process
 *  @sig: signal to be sent
3329 3330
 *  @act: new sigaction
 *  @oact: used to save the previous sigaction
3331 3332
 *  @sigsetsize: size of sigset_t type
 */
3333 3334 3335 3336
SYSCALL_DEFINE4(rt_sigaction, int, sig,
		const struct sigaction __user *, act,
		struct sigaction __user *, oact,
		size_t, sigsetsize)
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3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358
{
	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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3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384
#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));
3385
		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
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3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396
		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));
3397
		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
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3398 3399 3400 3401 3402 3403 3404 3405
#ifdef __ARCH_HAS_SA_RESTORER
		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
				&oact->sa_restorer);
#endif
	}
	return ret;
}
#endif
3406
#endif /* !CONFIG_ODD_RT_SIGACTION */
L
Linus Torvalds 已提交
3407

3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 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
#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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3485

3486
#ifdef CONFIG_SGETMASK_SYSCALL
L
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3487 3488 3489 3490

/*
 * For backwards compatibility.  Functionality superseded by sigprocmask.
 */
3491
SYSCALL_DEFINE0(sgetmask)
L
Linus Torvalds 已提交
3492 3493 3494 3495 3496
{
	/* SMP safe */
	return current->blocked.sig[0];
}

3497
SYSCALL_DEFINE1(ssetmask, int, newmask)
L
Linus Torvalds 已提交
3498
{
3499 3500
	int old = current->blocked.sig[0];
	sigset_t newset;
L
Linus Torvalds 已提交
3501

3502
	siginitset(&newset, newmask);
3503
	set_current_blocked(&newset);
L
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3504 3505 3506

	return old;
}
3507
#endif /* CONFIG_SGETMASK_SYSCALL */
L
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3508 3509 3510 3511 3512

#ifdef __ARCH_WANT_SYS_SIGNAL
/*
 * For backwards compatibility.  Functionality superseded by sigaction.
 */
3513
SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
L
Linus Torvalds 已提交
3514 3515 3516 3517 3518 3519
{
	struct k_sigaction new_sa, old_sa;
	int ret;

	new_sa.sa.sa_handler = handler;
	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3520
	sigemptyset(&new_sa.sa.sa_mask);
L
Linus Torvalds 已提交
3521 3522 3523 3524 3525 3526 3527 3528 3529

	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

3530
SYSCALL_DEFINE0(pause)
L
Linus Torvalds 已提交
3531
{
3532
	while (!signal_pending(current)) {
3533
		__set_current_state(TASK_INTERRUPTIBLE);
3534 3535
		schedule();
	}
L
Linus Torvalds 已提交
3536 3537 3538 3539 3540
	return -ERESTARTNOHAND;
}

#endif

3541
static int sigsuspend(sigset_t *set)
A
Al Viro 已提交
3542 3543 3544 3545
{
	current->saved_sigmask = current->blocked;
	set_current_blocked(set);

3546 3547 3548 3549
	while (!signal_pending(current)) {
		__set_current_state(TASK_INTERRUPTIBLE);
		schedule();
	}
A
Al Viro 已提交
3550 3551 3552 3553
	set_restore_sigmask();
	return -ERESTARTNOHAND;
}

3554 3555 3556 3557 3558 3559
/**
 *  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
 */
3560
SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3561 3562 3563 3564 3565 3566 3567 3568 3569
{
	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
3570
	return sigsuspend(&newset);
3571
}
A
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3572 3573 3574 3575 3576 3577 3578 3579 3580 3581 3582 3583 3584 3585 3586 3587 3588 3589 3590 3591 3592 3593
 
#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
3594

3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606 3607 3608 3609 3610
#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
3611

3612
__weak const char *arch_vma_name(struct vm_area_struct *vma)
3613 3614 3615 3616
{
	return NULL;
}

L
Linus Torvalds 已提交
3617 3618
void __init signals_init(void)
{
3619 3620 3621 3622
	/* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
	BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
		!= offsetof(struct siginfo, _sifields._pad));

3623
	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
L
Linus Torvalds 已提交
3624
}
3625 3626 3627 3628 3629 3630 3631 3632 3633 3634 3635 3636 3637 3638 3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661 3662 3663 3664

#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 */