signal.c 101.7 KB
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/*
 *  linux/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
 *
 *  2003-06-02  Jim Houston - Concurrent Computer Corp.
 *		Changes to use preallocated sigqueue structures
 *		to allow signals to be sent reliably.
 */

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

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static struct kmem_cache *sigqueue_cachep;
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int print_fatal_signals __read_mostly;

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

	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
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	    handler == SIG_DFL && !(force && sig_kernel_only(sig)))
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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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	/*
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	 * Tracers may want to know about even ignored signal unless it
	 * is SIGKILL which can't be reported anyway but can be ignored
	 * by SIGNAL_UNKILLABLE task.
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	 */
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	if (t->ptrace && sig != SIGKILL)
		return 0;

	return sig_task_ignored(t, sig, force);
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}

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

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

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

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

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

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

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

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

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

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}

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

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

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

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

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

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

	if (!print_fatal_signals)
		return;

	if (!__ratelimit(&ratelimit_state))
		return;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	flush_signals(t);
}

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

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

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

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

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

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

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

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

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

			if (!hrtimer_is_queued(tmr) &&
T
Thomas Gleixner 已提交
607
			    tsk->signal->it_real_incr != 0) {
608 609 610 611 612
				hrtimer_forward(tmr, tmr->base->get_time(),
						tsk->signal->it_real_incr);
				hrtimer_restart(tmr);
			}
		}
613
#endif
614
	}
615

D
Davide Libenzi 已提交
616
	recalc_sigpending();
617 618 619 620
	if (!signr)
		return 0;

	if (unlikely(sig_kernel_stop(signr))) {
621 622 623 624 625 626 627 628 629 630 631 632
		/*
		 * 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.
		 */
633
		current->jobctl |= JOBCTL_STOP_DEQUEUED;
634
	}
635
#ifdef CONFIG_POSIX_TIMERS
636
	if (resched_timer) {
L
Linus Torvalds 已提交
637 638 639 640 641 642 643
		/*
		 * 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);
644
		posixtimer_rearm(info);
L
Linus Torvalds 已提交
645
		spin_lock(&tsk->sighand->siglock);
646 647 648

		/* Don't expose the si_sys_private value to userspace */
		info->si_sys_private = 0;
L
Linus Torvalds 已提交
649
	}
650
#endif
L
Linus Torvalds 已提交
651 652 653 654 655 656 657 658 659 660 661 662 663 664
	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
 */
665
void signal_wake_up_state(struct task_struct *t, unsigned int state)
L
Linus Torvalds 已提交
666 667 668
{
	set_tsk_thread_flag(t, TIF_SIGPENDING);
	/*
669
	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
M
Matthew Wilcox 已提交
670
	 * case. We don't check t->state here because there is a race with it
L
Linus Torvalds 已提交
671 672 673 674
	 * 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.
	 */
675
	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
L
Linus Torvalds 已提交
676 677 678
		kick_process(t);
}

679 680 681 682 683 684
/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 */
685
static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
686 687 688 689 690 691 692 693
{
	struct sigqueue *q, *n;
	sigset_t m;

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

694
	sigandnsets(&s->signal, &s->signal, mask);
695 696 697 698 699 700 701 702
	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
703

704 705 706 707 708 709 710 711 712 713 714
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));
}

715 716 717 718 719 720 721 722
/*
 * 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);

723 724 725 726
	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))
727 728
		return 1;

729
	if (ns_capable(tcred->user_ns, CAP_KILL))
730 731 732 733 734
		return 1;

	return 0;
}

L
Linus Torvalds 已提交
735 736
/*
 * Bad permissions for sending the signal
737
 * - the caller must hold the RCU read lock
L
Linus Torvalds 已提交
738 739 740 741
 */
static int check_kill_permission(int sig, struct siginfo *info,
				 struct task_struct *t)
{
742
	struct pid *sid;
743 744
	int error;

745
	if (!valid_signal(sig))
746 747
		return -EINVAL;

748
	if (!si_fromuser(info))
749
		return 0;
A
Amy Griffis 已提交
750

751 752
	error = audit_signal_info(sig, t); /* Let audit system see the signal */
	if (error)
L
Linus Torvalds 已提交
753
		return error;
754

755
	if (!same_thread_group(current, t) &&
756
	    !kill_ok_by_cred(t)) {
757 758 759 760 761 762 763 764 765 766 767 768 769
		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;
		}
	}
770

A
Amy Griffis 已提交
771
	return security_task_kill(t, info, sig, 0);
L
Linus Torvalds 已提交
772 773
}

774 775 776 777 778 779 780 781
/**
 * 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
782 783 784 785 786
 * 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.
787 788 789 790 791 792 793 794 795 796
 *
 * 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);
797
	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
798 799
}

L
Linus Torvalds 已提交
800
/*
801 802
 * 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
803 804
 * time regardless of blocking, ignoring, or handling.  This does the
 * actual continuing for SIGCONT, but not the actual stopping for stop
805 806 807 808
 * 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
809
 */
810
static bool prepare_signal(int sig, struct task_struct *p, bool force)
L
Linus Torvalds 已提交
811
{
812
	struct signal_struct *signal = p->signal;
L
Linus Torvalds 已提交
813
	struct task_struct *t;
814
	sigset_t flush;
L
Linus Torvalds 已提交
815

816
	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
817
		if (!(signal->flags & SIGNAL_GROUP_EXIT))
818
			return sig == SIGKILL;
L
Linus Torvalds 已提交
819
		/*
820
		 * The process is in the middle of dying, nothing to do.
L
Linus Torvalds 已提交
821
		 */
822
	} else if (sig_kernel_stop(sig)) {
L
Linus Torvalds 已提交
823 824 825
		/*
		 * This is a stop signal.  Remove SIGCONT from all queues.
		 */
826
		siginitset(&flush, sigmask(SIGCONT));
827
		flush_sigqueue_mask(&flush, &signal->shared_pending);
828
		for_each_thread(p, t)
829
			flush_sigqueue_mask(&flush, &t->pending);
L
Linus Torvalds 已提交
830
	} else if (sig == SIGCONT) {
831
		unsigned int why;
L
Linus Torvalds 已提交
832
		/*
833
		 * Remove all stop signals from all queues, wake all threads.
L
Linus Torvalds 已提交
834
		 */
835
		siginitset(&flush, SIG_KERNEL_STOP_MASK);
836
		flush_sigqueue_mask(&flush, &signal->shared_pending);
837
		for_each_thread(p, t) {
838
			flush_sigqueue_mask(&flush, &t->pending);
839
			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
840 841 842 843
			if (likely(!(t->ptrace & PT_SEIZED)))
				wake_up_state(t, __TASK_STOPPED);
			else
				ptrace_trap_notify(t);
844
		}
L
Linus Torvalds 已提交
845

846 847 848 849 850 851 852 853 854
		/*
		 * 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;
855
		if (signal->flags & SIGNAL_STOP_STOPPED)
856
			why |= SIGNAL_CLD_CONTINUED;
857
		else if (signal->group_stop_count)
858 859 860
			why |= SIGNAL_CLD_STOPPED;

		if (why) {
861
			/*
862
			 * The first thread which returns from do_signal_stop()
863 864 865
			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
			 * notify its parent. See get_signal_to_deliver().
			 */
866
			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
867 868
			signal->group_stop_count = 0;
			signal->group_exit_code = 0;
L
Linus Torvalds 已提交
869 870
		}
	}
871

872
	return !sig_ignored(p, sig, force);
L
Linus Torvalds 已提交
873 874
}

875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895
/*
 * 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);
}

896
static void complete_signal(int sig, struct task_struct *p, int group)
897 898 899 900 901 902 903 904 905 906 907 908
{
	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;
909
	else if (!group || thread_group_empty(p))
910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
		/*
		 * 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.
	 */
937
	if (sig_fatal(p, sig) &&
938
	    !(signal->flags & SIGNAL_GROUP_EXIT) &&
939
	    !sigismember(&t->real_blocked, sig) &&
940
	    (sig == SIGKILL || !p->ptrace)) {
941 942 943 944 945 946 947 948 949 950 951 952 953 954 955
		/*
		 * 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 {
956
				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
957 958 959 960 961 962 963 964 965 966 967 968 969 970 971
				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;
}

972 973 974 975 976
static inline int legacy_queue(struct sigpending *signals, int sig)
{
	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
}

977 978 979 980 981 982 983 984 985
#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;

986 987 988 989
	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();
990 991 992 993 994 995 996 997
}
#else
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
{
	return;
}
#endif

998 999
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
1000
{
1001
	struct sigpending *pending;
1002
	struct sigqueue *q;
1003
	int override_rlimit;
1004
	int ret = 0, result;
1005

1006
	assert_spin_locked(&t->sighand->siglock);
1007

1008
	result = TRACE_SIGNAL_IGNORED;
1009 1010
	if (!prepare_signal(sig, t,
			from_ancestor_ns || (info == SEND_SIG_FORCED)))
1011
		goto ret;
1012 1013

	pending = group ? &t->signal->shared_pending : &t->pending;
1014 1015 1016 1017 1018
	/*
	 * 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.
	 */
1019
	result = TRACE_SIGNAL_ALREADY_PENDING;
1020
	if (legacy_queue(pending, sig))
1021 1022 1023
		goto ret;

	result = TRACE_SIGNAL_DELIVERED;
L
Linus Torvalds 已提交
1024 1025 1026 1027
	/*
	 * fast-pathed signals for kernel-internal things like SIGSTOP
	 * or SIGKILL.
	 */
1028
	if (info == SEND_SIG_FORCED)
L
Linus Torvalds 已提交
1029 1030
		goto out_set;

1031 1032 1033 1034 1035 1036 1037 1038 1039
	/*
	 * 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.
	 */
1040 1041 1042 1043 1044
	if (sig < SIGRTMIN)
		override_rlimit = (is_si_special(info) || info->si_code >= 0);
	else
		override_rlimit = 0;

1045
	q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit);
L
Linus Torvalds 已提交
1046
	if (q) {
1047
		list_add_tail(&q->list, &pending->list);
L
Linus Torvalds 已提交
1048
		switch ((unsigned long) info) {
1049
		case (unsigned long) SEND_SIG_NOINFO:
1050
			clear_siginfo(&q->info);
L
Linus Torvalds 已提交
1051 1052 1053
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_USER;
1054
			q->info.si_pid = task_tgid_nr_ns(current,
1055
							task_active_pid_ns(t));
1056
			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1057
			break;
1058
		case (unsigned long) SEND_SIG_PRIV:
1059
			clear_siginfo(&q->info);
L
Linus Torvalds 已提交
1060 1061 1062 1063 1064 1065 1066 1067
			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);
1068 1069
			if (from_ancestor_ns)
				q->info.si_pid = 0;
L
Linus Torvalds 已提交
1070 1071
			break;
		}
1072 1073 1074

		userns_fixup_signal_uid(&q->info, t);

1075
	} else if (!is_si_special(info)) {
1076 1077 1078 1079 1080 1081
		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().
			 */
1082 1083 1084
			result = TRACE_SIGNAL_OVERFLOW_FAIL;
			ret = -EAGAIN;
			goto ret;
1085 1086 1087 1088 1089
		} else {
			/*
			 * This is a silent loss of information.  We still
			 * send the signal, but the *info bits are lost.
			 */
1090
			result = TRACE_SIGNAL_LOSE_INFO;
1091
		}
L
Linus Torvalds 已提交
1092 1093 1094
	}

out_set:
1095
	signalfd_notify(t, sig);
1096
	sigaddset(&pending->signal, sig);
1097
	complete_signal(sig, t, group);
1098 1099 1100
ret:
	trace_signal_generate(sig, info, t, group, result);
	return ret;
L
Linus Torvalds 已提交
1101 1102
}

1103 1104 1105
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
			int group)
{
1106 1107 1108
	int from_ancestor_ns = 0;

#ifdef CONFIG_PID_NS
1109 1110
	from_ancestor_ns = si_fromuser(info) &&
			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1111 1112 1113
#endif

	return __send_signal(sig, info, t, group, from_ancestor_ns);
1114 1115
}

1116
static void print_fatal_signal(int signr)
I
Ingo Molnar 已提交
1117
{
1118
	struct pt_regs *regs = signal_pt_regs();
1119
	pr_info("potentially unexpected fatal signal %d.\n", signr);
I
Ingo Molnar 已提交
1120

A
Al Viro 已提交
1121
#if defined(__i386__) && !defined(__arch_um__)
1122
	pr_info("code at %08lx: ", regs->ip);
I
Ingo Molnar 已提交
1123 1124 1125 1126 1127
	{
		int i;
		for (i = 0; i < 16; i++) {
			unsigned char insn;

1128 1129
			if (get_user(insn, (unsigned char *)(regs->ip + i)))
				break;
1130
			pr_cont("%02x ", insn);
I
Ingo Molnar 已提交
1131 1132
		}
	}
1133
	pr_cont("\n");
I
Ingo Molnar 已提交
1134
#endif
1135
	preempt_disable();
I
Ingo Molnar 已提交
1136
	show_regs(regs);
1137
	preempt_enable();
I
Ingo Molnar 已提交
1138 1139 1140 1141 1142 1143 1144 1145 1146 1147
}

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
1148

1149 1150 1151 1152 1153 1154
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
1155 1156 1157
static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
1158
	return send_signal(sig, info, t, 0);
L
Linus Torvalds 已提交
1159 1160
}

1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174
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
1175 1176 1177
/*
 * Force a signal that the process can't ignore: if necessary
 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1178 1179 1180 1181 1182
 *
 * 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.
 *
1183 1184
 * 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
1185 1186 1187 1188 1189
 */
int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
	unsigned long int flags;
1190 1191
	int ret, blocked, ignored;
	struct k_sigaction *action;
L
Linus Torvalds 已提交
1192 1193

	spin_lock_irqsave(&t->sighand->siglock, flags);
1194 1195 1196 1197 1198 1199 1200
	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
1201
			recalc_sigpending_and_wake(t);
1202
		}
L
Linus Torvalds 已提交
1203
	}
1204 1205 1206 1207 1208
	/*
	 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
	 * debugging to leave init killable.
	 */
	if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
1209
		t->signal->flags &= ~SIGNAL_UNKILLABLE;
L
Linus Torvalds 已提交
1210 1211 1212 1213 1214 1215 1216 1217 1218
	ret = specific_send_sig_info(sig, info, t);
	spin_unlock_irqrestore(&t->sighand->siglock, flags);

	return ret;
}

/*
 * Nuke all other threads in the group.
 */
1219
int zap_other_threads(struct task_struct *p)
L
Linus Torvalds 已提交
1220
{
1221 1222
	struct task_struct *t = p;
	int count = 0;
L
Linus Torvalds 已提交
1223 1224 1225

	p->signal->group_stop_count = 0;

1226
	while_each_thread(p, t) {
1227
		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1228 1229 1230
		count++;

		/* Don't bother with already dead threads */
L
Linus Torvalds 已提交
1231 1232 1233 1234 1235
		if (t->exit_state)
			continue;
		sigaddset(&t->pending.signal, SIGKILL);
		signal_wake_up(t, 1);
	}
1236 1237

	return count;
L
Linus Torvalds 已提交
1238 1239
}

1240 1241
struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
					   unsigned long *flags)
1242 1243 1244 1245
{
	struct sighand_struct *sighand;

	for (;;) {
1246 1247 1248 1249
		/*
		 * Disable interrupts early to avoid deadlocks.
		 * See rcu_read_unlock() comment header for details.
		 */
1250 1251
		local_irq_save(*flags);
		rcu_read_lock();
1252
		sighand = rcu_dereference(tsk->sighand);
1253 1254 1255
		if (unlikely(sighand == NULL)) {
			rcu_read_unlock();
			local_irq_restore(*flags);
1256
			break;
1257
		}
1258 1259
		/*
		 * This sighand can be already freed and even reused, but
1260
		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
1261 1262 1263 1264 1265 1266 1267 1268
		 * 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.
		 */
1269 1270 1271
		spin_lock(&sighand->siglock);
		if (likely(sighand == tsk->sighand)) {
			rcu_read_unlock();
1272
			break;
1273 1274 1275 1276
		}
		spin_unlock(&sighand->siglock);
		rcu_read_unlock();
		local_irq_restore(*flags);
1277 1278 1279 1280 1281
	}

	return sighand;
}

1282 1283 1284
/*
 * send signal info to all the members of a group
 */
L
Linus Torvalds 已提交
1285 1286
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
1287 1288 1289 1290 1291
	int ret;

	rcu_read_lock();
	ret = check_kill_permission(sig, info, p);
	rcu_read_unlock();
1292

1293 1294
	if (!ret && sig)
		ret = do_send_sig_info(sig, info, p, true);
L
Linus Torvalds 已提交
1295 1296 1297 1298 1299

	return ret;
}

/*
1300
 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
L
Linus Torvalds 已提交
1301
 * control characters do (^C, ^Z etc)
1302
 * - the caller must hold at least a readlock on tasklist_lock
L
Linus Torvalds 已提交
1303
 */
1304
int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
L
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1305 1306 1307 1308 1309 1310
{
	struct task_struct *p = NULL;
	int retval, success;

	success = 0;
	retval = -ESRCH;
1311
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
L
Linus Torvalds 已提交
1312 1313 1314
		int err = group_send_sig_info(sig, info, p);
		success |= !err;
		retval = err;
1315
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
L
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1316 1317 1318
	return success ? 0 : retval;
}

1319
int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
L
Linus Torvalds 已提交
1320
{
1321
	int error = -ESRCH;
L
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1322 1323
	struct task_struct *p;

1324 1325 1326 1327 1328 1329 1330 1331
	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;
1332

1333 1334 1335 1336 1337 1338
		/*
		 * 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
1339 1340
}

1341
static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1342 1343 1344
{
	int error;
	rcu_read_lock();
1345
	error = kill_pid_info(sig, info, find_vpid(pid));
1346 1347 1348 1349
	rcu_read_unlock();
	return error;
}

1350 1351 1352 1353
static int kill_as_cred_perm(const struct cred *cred,
			     struct task_struct *target)
{
	const struct cred *pcred = __task_cred(target);
1354 1355
	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))
1356 1357 1358 1359
		return 0;
	return 1;
}

1360
/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1361 1362
int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
			 const struct cred *cred, u32 secid)
1363 1364 1365
{
	int ret = -EINVAL;
	struct task_struct *p;
1366
	unsigned long flags;
1367 1368 1369 1370

	if (!valid_signal(sig))
		return ret;

1371
	rcu_read_lock();
1372
	p = pid_task(pid, PIDTYPE_PID);
1373 1374 1375 1376
	if (!p) {
		ret = -ESRCH;
		goto out_unlock;
	}
1377
	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1378 1379 1380
		ret = -EPERM;
		goto out_unlock;
	}
1381 1382 1383
	ret = security_task_kill(p, info, sig, secid);
	if (ret)
		goto out_unlock;
1384 1385 1386 1387 1388 1389 1390

	if (sig) {
		if (lock_task_sighand(p, &flags)) {
			ret = __send_signal(sig, info, p, 1, 0);
			unlock_task_sighand(p, &flags);
		} else
			ret = -ESRCH;
1391 1392
	}
out_unlock:
1393
	rcu_read_unlock();
1394 1395
	return ret;
}
1396
EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
L
Linus Torvalds 已提交
1397 1398 1399 1400 1401 1402 1403 1404

/*
 * 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.
 */

1405
static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
L
Linus Torvalds 已提交
1406
{
1407
	int ret;
1408 1409 1410 1411 1412 1413 1414 1415

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

1416 1417 1418 1419
	/* -INT_MIN is undefined.  Exclude this case to avoid a UBSAN warning */
	if (pid == INT_MIN)
		return -ESRCH;

1420 1421 1422 1423 1424
	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
1425 1426 1427 1428
		int retval = 0, count = 0;
		struct task_struct * p;

		for_each_process(p) {
1429 1430
			if (task_pid_vnr(p) > 1 &&
					!same_thread_group(p, current)) {
L
Linus Torvalds 已提交
1431 1432 1433 1434 1435 1436
				int err = group_send_sig_info(sig, info, p);
				++count;
				if (err != -EPERM)
					retval = err;
			}
		}
1437
		ret = count ? retval : -ESRCH;
L
Linus Torvalds 已提交
1438
	}
1439 1440
	read_unlock(&tasklist_lock);

1441
	return ret;
L
Linus Torvalds 已提交
1442 1443 1444 1445 1446 1447
}

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

1448
int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
L
Linus Torvalds 已提交
1449 1450 1451 1452 1453
{
	/*
	 * Make sure legacy kernel users don't send in bad values
	 * (normal paths check this in check_kill_permission).
	 */
1454
	if (!valid_signal(sig))
L
Linus Torvalds 已提交
1455 1456
		return -EINVAL;

1457
	return do_send_sig_info(sig, info, p, false);
L
Linus Torvalds 已提交
1458 1459
}

1460 1461 1462
#define __si_special(priv) \
	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)

L
Linus Torvalds 已提交
1463 1464 1465
int
send_sig(int sig, struct task_struct *p, int priv)
{
1466
	return send_sig_info(sig, __si_special(priv), p);
L
Linus Torvalds 已提交
1467 1468 1469 1470 1471
}

void
force_sig(int sig, struct task_struct *p)
{
1472
	force_sig_info(sig, SEND_SIG_PRIV, p);
L
Linus Torvalds 已提交
1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493
}

/*
 * 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;
}

1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540
int force_sig_fault(int sig, int code, void __user *addr
	___ARCH_SI_TRAPNO(int trapno)
	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
	, struct task_struct *t)
{
	struct siginfo info;

	clear_siginfo(&info);
	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code  = code;
	info.si_addr  = addr;
#ifdef __ARCH_SI_TRAPNO
	info.si_trapno = trapno;
#endif
#ifdef __ia64__
	info.si_imm = imm;
	info.si_flags = flags;
	info.si_isr = isr;
#endif
	return force_sig_info(info.si_signo, &info, t);
}

int send_sig_fault(int sig, int code, void __user *addr
	___ARCH_SI_TRAPNO(int trapno)
	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
	, struct task_struct *t)
{
	struct siginfo info;

	clear_siginfo(&info);
	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code  = code;
	info.si_addr  = addr;
#ifdef __ARCH_SI_TRAPNO
	info.si_trapno = trapno;
#endif
#ifdef __ia64__
	info.si_imm = imm;
	info.si_flags = flags;
	info.si_isr = isr;
#endif
	return send_sig_info(info.si_signo, &info, t);
}


1541 1542
int kill_pgrp(struct pid *pid, int sig, int priv)
{
1543 1544 1545 1546 1547 1548 1549
	int ret;

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

	return ret;
1550 1551 1552 1553 1554 1555 1556 1557 1558
}
EXPORT_SYMBOL(kill_pgrp);

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

L
Linus Torvalds 已提交
1559 1560 1561 1562
/*
 * 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
1563
 * expirations or I/O completions".  In the case of POSIX Timers
L
Linus Torvalds 已提交
1564 1565 1566 1567 1568 1569
 * 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)
{
1570
	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
L
Linus Torvalds 已提交
1571

1572
	if (q)
L
Linus Torvalds 已提交
1573
		q->flags |= SIGQUEUE_PREALLOC;
1574 1575

	return q;
L
Linus Torvalds 已提交
1576 1577 1578 1579 1580
}

void sigqueue_free(struct sigqueue *q)
{
	unsigned long flags;
1581 1582
	spinlock_t *lock = &current->sighand->siglock;

L
Linus Torvalds 已提交
1583 1584
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
	/*
1585 1586
	 * We must hold ->siglock while testing q->list
	 * to serialize with collect_signal() or with
1587
	 * __exit_signal()->flush_sigqueue().
L
Linus Torvalds 已提交
1588
	 */
1589
	spin_lock_irqsave(lock, flags);
1590 1591 1592 1593 1594
	q->flags &= ~SIGQUEUE_PREALLOC;
	/*
	 * If it is queued it will be freed when dequeued,
	 * like the "regular" sigqueue.
	 */
1595
	if (!list_empty(&q->list))
1596
		q = NULL;
1597 1598
	spin_unlock_irqrestore(lock, flags);

1599 1600
	if (q)
		__sigqueue_free(q);
L
Linus Torvalds 已提交
1601 1602
}

1603
int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1604
{
1605
	int sig = q->info.si_signo;
1606
	struct sigpending *pending;
1607
	unsigned long flags;
1608
	int ret, result;
1609

1610
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1611 1612 1613 1614 1615

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

1616
	ret = 1; /* the signal is ignored */
1617
	result = TRACE_SIGNAL_IGNORED;
1618
	if (!prepare_signal(sig, t, false))
1619 1620 1621
		goto out;

	ret = 0;
1622 1623 1624 1625 1626 1627 1628
	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++;
1629
		result = TRACE_SIGNAL_ALREADY_PENDING;
1630
		goto out;
1631
	}
1632
	q->info.si_overrun = 0;
1633 1634

	signalfd_notify(t, sig);
1635
	pending = group ? &t->signal->shared_pending : &t->pending;
1636 1637
	list_add_tail(&q->list, &pending->list);
	sigaddset(&pending->signal, sig);
1638
	complete_signal(sig, t, group);
1639
	result = TRACE_SIGNAL_DELIVERED;
1640
out:
1641
	trace_signal_generate(sig, &q->info, t, group, result);
1642 1643 1644
	unlock_task_sighand(t, &flags);
ret:
	return ret;
1645 1646
}

L
Linus Torvalds 已提交
1647 1648 1649
/*
 * 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
1650
 *
1651 1652
 * Returns true if our parent ignored us and so we've switched to
 * self-reaping.
L
Linus Torvalds 已提交
1653
 */
1654
bool do_notify_parent(struct task_struct *tsk, int sig)
L
Linus Torvalds 已提交
1655 1656 1657 1658
{
	struct siginfo info;
	unsigned long flags;
	struct sighand_struct *psig;
1659
	bool autoreap = false;
1660
	u64 utime, stime;
L
Linus Torvalds 已提交
1661 1662 1663 1664

	BUG_ON(sig == -1);

 	/* do_notify_parent_cldstop should have been called instead.  */
M
Matthew Wilcox 已提交
1665
 	BUG_ON(task_is_stopped_or_traced(tsk));
L
Linus Torvalds 已提交
1666

T
Tejun Heo 已提交
1667
	BUG_ON(!tsk->ptrace &&
L
Linus Torvalds 已提交
1668 1669
	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));

1670 1671 1672 1673 1674 1675 1676 1677 1678
	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;
	}

1679
	clear_siginfo(&info);
L
Linus Torvalds 已提交
1680 1681
	info.si_signo = sig;
	info.si_errno = 0;
1682
	/*
1683 1684
	 * We are under tasklist_lock here so our parent is tied to
	 * us and cannot change.
1685
	 *
1686 1687
	 * task_active_pid_ns will always return the same pid namespace
	 * until a task passes through release_task.
1688 1689 1690 1691 1692 1693
	 *
	 * 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();
1694
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1695 1696
	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
				       task_uid(tsk));
1697 1698
	rcu_read_unlock();

1699 1700 1701
	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
1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714

	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
1715
	if (!tsk->ptrace && sig == SIGCHLD &&
L
Linus Torvalds 已提交
1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732
	    (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).
		 */
1733
		autoreap = true;
L
Linus Torvalds 已提交
1734
		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1735
			sig = 0;
L
Linus Torvalds 已提交
1736
	}
1737
	if (valid_signal(sig) && sig)
L
Linus Torvalds 已提交
1738 1739 1740
		__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
1741

1742
	return autoreap;
L
Linus Torvalds 已提交
1743 1744
}

1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759
/**
 * 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
1760 1761 1762
{
	struct siginfo info;
	unsigned long flags;
1763
	struct task_struct *parent;
L
Linus Torvalds 已提交
1764
	struct sighand_struct *sighand;
1765
	u64 utime, stime;
L
Linus Torvalds 已提交
1766

1767
	if (for_ptracer) {
1768
		parent = tsk->parent;
1769
	} else {
1770 1771 1772 1773
		tsk = tsk->group_leader;
		parent = tsk->real_parent;
	}

1774
	clear_siginfo(&info);
L
Linus Torvalds 已提交
1775 1776
	info.si_signo = SIGCHLD;
	info.si_errno = 0;
1777
	/*
1778
	 * see comment in do_notify_parent() about the following 4 lines
1779 1780
	 */
	rcu_read_lock();
1781
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1782
	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1783 1784
	rcu_read_unlock();

1785 1786 1787
	task_cputime(tsk, &utime, &stime);
	info.si_utime = nsec_to_clock_t(utime);
	info.si_stime = nsec_to_clock_t(stime);
L
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1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815

 	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);
}

1816 1817
static inline int may_ptrace_stop(void)
{
T
Tejun Heo 已提交
1818
	if (!likely(current->ptrace))
1819 1820 1821 1822 1823 1824 1825
		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
1826
	 * ->siglock we must see ->core_state != NULL. Otherwise it
1827
	 * is safe to enter schedule().
1828 1829 1830 1831
	 *
	 * 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.
1832
	 */
1833
	if (unlikely(current->mm->core_state) &&
1834 1835 1836 1837 1838 1839
	    unlikely(current->mm == current->parent->mm))
		return 0;

	return 1;
}

R
Roland McGrath 已提交
1840
/*
1841
 * Return non-zero if there is a SIGKILL that should be waking us up.
R
Roland McGrath 已提交
1842 1843 1844 1845
 * Called with the siglock held.
 */
static int sigkill_pending(struct task_struct *tsk)
{
1846 1847
	return	sigismember(&tsk->pending.signal, SIGKILL) ||
		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
R
Roland McGrath 已提交
1848 1849
}

L
Linus Torvalds 已提交
1850 1851 1852 1853 1854 1855 1856 1857
/*
 * 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.
 *
1858 1859
 * 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
1860
 */
T
Tejun Heo 已提交
1861
static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1862 1863
	__releases(&current->sighand->siglock)
	__acquires(&current->sighand->siglock)
L
Linus Torvalds 已提交
1864
{
1865 1866
	bool gstop_done = false;

R
Roland McGrath 已提交
1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881
	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);
1882 1883
		if (sigkill_pending(current))
			return;
R
Roland McGrath 已提交
1884 1885
	}

L
Linus Torvalds 已提交
1886
	/*
1887 1888 1889 1890 1891
	 * 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
1892
	 */
1893
	set_current_state(TASK_TRACED);
L
Linus Torvalds 已提交
1894 1895 1896 1897

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

1898
	/*
1899 1900
	 * If @why is CLD_STOPPED, we're trapping to participate in a group
	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1901 1902 1903
	 * 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.
1904
	 */
1905
	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1906
		gstop_done = task_participate_group_stop(current);
1907

1908
	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1909
	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1910 1911
	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1912

1913
	/* entering a trap, clear TRAPPING */
1914
	task_clear_jobctl_trapping(current);
1915

L
Linus Torvalds 已提交
1916 1917
	spin_unlock_irq(&current->sighand->siglock);
	read_lock(&tasklist_lock);
1918
	if (may_ptrace_stop()) {
1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929
		/*
		 * 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);
1930
		if (gstop_done && ptrace_reparented(current))
1931 1932
			do_notify_parent_cldstop(current, false, why);

M
Miklos Szeredi 已提交
1933 1934 1935 1936 1937 1938 1939
		/*
		 * 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
1940
		read_unlock(&tasklist_lock);
M
Miklos Szeredi 已提交
1941
		preempt_enable_no_resched();
1942
		freezable_schedule();
L
Linus Torvalds 已提交
1943 1944 1945
	} else {
		/*
		 * By the time we got the lock, our tracer went away.
1946
		 * Don't drop the lock yet, another tracer may come.
1947 1948 1949
		 *
		 * If @gstop_done, the ptracer went away between group stop
		 * completion and here.  During detach, it would have set
1950 1951 1952
		 * 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
1953
		 */
1954 1955 1956
		if (gstop_done)
			do_notify_parent_cldstop(current, false, why);

1957
		/* tasklist protects us from ptrace_freeze_traced() */
1958
		__set_current_state(TASK_RUNNING);
1959 1960
		if (clear_code)
			current->exit_code = 0;
1961
		read_unlock(&tasklist_lock);
L
Linus Torvalds 已提交
1962 1963 1964 1965 1966 1967 1968 1969 1970 1971
	}

	/*
	 * 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
1972 1973 1974
	/* LISTENING can be set only during STOP traps, clear it */
	current->jobctl &= ~JOBCTL_LISTENING;

L
Linus Torvalds 已提交
1975 1976 1977
	/*
	 * Queued signals ignored us while we were stopped for tracing.
	 * So check for any that we should take before resuming user mode.
1978
	 * This sets TIF_SIGPENDING, but never clears it.
L
Linus Torvalds 已提交
1979
	 */
1980
	recalc_sigpending_tsk(current);
L
Linus Torvalds 已提交
1981 1982
}

T
Tejun Heo 已提交
1983
static void ptrace_do_notify(int signr, int exit_code, int why)
L
Linus Torvalds 已提交
1984 1985 1986
{
	siginfo_t info;

1987
	clear_siginfo(&info);
T
Tejun Heo 已提交
1988
	info.si_signo = signr;
L
Linus Torvalds 已提交
1989
	info.si_code = exit_code;
1990
	info.si_pid = task_pid_vnr(current);
1991
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1992 1993

	/* Let the debugger run.  */
T
Tejun Heo 已提交
1994 1995 1996 1997 1998 1999
	ptrace_stop(exit_code, why, 1, &info);
}

void ptrace_notify(int exit_code)
{
	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
2000 2001
	if (unlikely(current->task_works))
		task_work_run();
T
Tejun Heo 已提交
2002

L
Linus Torvalds 已提交
2003
	spin_lock_irq(&current->sighand->siglock);
T
Tejun Heo 已提交
2004
	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
L
Linus Torvalds 已提交
2005 2006 2007
	spin_unlock_irq(&current->sighand->siglock);
}

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
/**
 * 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
2029
 */
2030 2031
static bool do_signal_stop(int signr)
	__releases(&current->sighand->siglock)
L
Linus Torvalds 已提交
2032 2033 2034
{
	struct signal_struct *sig = current->signal;

2035
	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
2036
		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2037 2038
		struct task_struct *t;

2039 2040
		/* signr will be recorded in task->jobctl for retries */
		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2041

2042
		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2043
		    unlikely(signal_group_exit(sig)))
2044
			return false;
L
Linus Torvalds 已提交
2045
		/*
2046 2047 2048 2049 2050 2051 2052
		 * 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
2053 2054
		 * cause two group stops when !ptraced.  That is why we
		 * also check !task_is_stopped(t) below.
2055 2056 2057 2058 2059 2060 2061 2062
		 *
		 * 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
2063
		 */
2064 2065
		if (!(sig->flags & SIGNAL_STOP_STOPPED))
			sig->group_exit_code = signr;
L
Linus Torvalds 已提交
2066

2067 2068 2069 2070
		sig->group_stop_count = 0;

		if (task_set_jobctl_pending(current, signr | gstop))
			sig->group_stop_count++;
L
Linus Torvalds 已提交
2071

2072 2073
		t = current;
		while_each_thread(current, t) {
L
Linus Torvalds 已提交
2074
			/*
2075 2076 2077
			 * 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
2078
			 */
2079 2080
			if (!task_is_stopped(t) &&
			    task_set_jobctl_pending(t, signr | gstop)) {
2081
				sig->group_stop_count++;
2082 2083 2084 2085
				if (likely(!(t->ptrace & PT_SEIZED)))
					signal_wake_up(t, 0);
				else
					ptrace_trap_notify(t);
2086
			}
2087
		}
L
Linus Torvalds 已提交
2088
	}
2089

T
Tejun Heo 已提交
2090
	if (likely(!current->ptrace)) {
2091
		int notify = 0;
L
Linus Torvalds 已提交
2092

2093 2094 2095 2096 2097 2098 2099 2100
		/*
		 * 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;

2101
		__set_current_state(TASK_STOPPED);
2102 2103
		spin_unlock_irq(&current->sighand->siglock);

2104 2105 2106 2107 2108 2109 2110 2111 2112
		/*
		 * 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.
		 */
2113 2114
		if (notify) {
			read_lock(&tasklist_lock);
2115
			do_notify_parent_cldstop(current, false, notify);
2116 2117 2118 2119
			read_unlock(&tasklist_lock);
		}

		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2120
		freezable_schedule();
2121
		return true;
2122
	} else {
2123 2124 2125 2126 2127 2128
		/*
		 * 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;
2129
	}
2130
}
L
Linus Torvalds 已提交
2131

2132 2133 2134
/**
 * do_jobctl_trap - take care of ptrace jobctl traps
 *
T
Tejun Heo 已提交
2135 2136 2137 2138 2139 2140 2141
 * 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.
2142 2143 2144 2145 2146 2147 2148
 *
 * 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
2149
	struct signal_struct *signal = current->signal;
2150
	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2151

T
Tejun Heo 已提交
2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162
	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;
2163
	}
L
Linus Torvalds 已提交
2164 2165
}

2166
static int ptrace_signal(int signr, siginfo_t *info)
R
Roland McGrath 已提交
2167
{
2168 2169 2170 2171 2172 2173 2174 2175 2176 2177
	/*
	 * 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
2178
	ptrace_stop(signr, CLD_TRAPPED, 0, info);
R
Roland McGrath 已提交
2179 2180 2181 2182 2183 2184 2185 2186

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

	current->exit_code = 0;

2187 2188 2189 2190 2191 2192
	/*
	 * 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
2193
	if (signr != info->si_signo) {
2194
		clear_siginfo(info);
R
Roland McGrath 已提交
2195 2196 2197
		info->si_signo = signr;
		info->si_errno = 0;
		info->si_code = SI_USER;
2198
		rcu_read_lock();
R
Roland McGrath 已提交
2199
		info->si_pid = task_pid_vnr(current->parent);
2200 2201
		info->si_uid = from_kuid_munged(current_user_ns(),
						task_uid(current->parent));
2202
		rcu_read_unlock();
R
Roland McGrath 已提交
2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213
	}

	/* 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;
}

2214
int get_signal(struct ksignal *ksig)
L
Linus Torvalds 已提交
2215
{
2216 2217 2218
	struct sighand_struct *sighand = current->sighand;
	struct signal_struct *signal = current->signal;
	int signr;
L
Linus Torvalds 已提交
2219

2220 2221
	if (unlikely(current->task_works))
		task_work_run();
2222

2223 2224 2225
	if (unlikely(uprobe_deny_signal()))
		return 0;

R
Roland McGrath 已提交
2226
	/*
2227 2228 2229
	 * 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
2230
	 */
2231 2232
	try_to_freeze();

2233
relock:
2234
	spin_lock_irq(&sighand->siglock);
2235 2236 2237 2238 2239
	/*
	 * 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.
	 */
2240
	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2241 2242 2243 2244 2245 2246 2247
		int why;

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

2248
		signal->flags &= ~SIGNAL_CLD_MASK;
2249

2250
		spin_unlock_irq(&sighand->siglock);
R
Roland McGrath 已提交
2251

2252 2253 2254 2255 2256 2257 2258 2259
		/*
		 * 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
2260
		read_lock(&tasklist_lock);
2261 2262
		do_notify_parent_cldstop(current, false, why);

2263 2264 2265
		if (ptrace_reparented(current->group_leader))
			do_notify_parent_cldstop(current->group_leader,
						true, why);
T
Tejun Heo 已提交
2266
		read_unlock(&tasklist_lock);
2267

2268 2269 2270
		goto relock;
	}

L
Linus Torvalds 已提交
2271 2272
	for (;;) {
		struct k_sigaction *ka;
2273

T
Tejun Heo 已提交
2274 2275
		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
		    do_signal_stop(0))
2276
			goto relock;
2277

2278 2279 2280 2281 2282
		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
			do_jobctl_trap();
			spin_unlock_irq(&sighand->siglock);
			goto relock;
		}
L
Linus Torvalds 已提交
2283

2284
		signr = dequeue_signal(current, &current->blocked, &ksig->info);
2285

T
Tejun Heo 已提交
2286 2287
		if (!signr)
			break; /* will return 0 */
2288

2289
		if (unlikely(current->ptrace) && signr != SIGKILL) {
2290
			signr = ptrace_signal(signr, &ksig->info);
T
Tejun Heo 已提交
2291 2292
			if (!signr)
				continue;
L
Linus Torvalds 已提交
2293 2294
		}

T
Tejun Heo 已提交
2295 2296
		ka = &sighand->action[signr-1];

2297
		/* Trace actually delivered signals. */
2298
		trace_signal_deliver(signr, &ksig->info, ka);
2299

L
Linus Torvalds 已提交
2300 2301 2302 2303
		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
			continue;
		if (ka->sa.sa_handler != SIG_DFL) {
			/* Run the handler.  */
2304
			ksig->ka = *ka;
L
Linus Torvalds 已提交
2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317

			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;

2318
		/*
2319
		 * Global init gets no signals it doesn't want.
2320 2321 2322 2323 2324 2325 2326
		 * 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.
2327
		 */
2328
		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2329
				!sig_kernel_only(signr))
L
Linus Torvalds 已提交
2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343
			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) {
2344
				spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2345 2346 2347

				/* signals can be posted during this window */

2348
				if (is_current_pgrp_orphaned())
L
Linus Torvalds 已提交
2349 2350
					goto relock;

2351
				spin_lock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2352 2353
			}

2354
			if (likely(do_signal_stop(ksig->info.si_signo))) {
L
Linus Torvalds 已提交
2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365
				/* It released the siglock.  */
				goto relock;
			}

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

2366
		spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2367 2368 2369 2370 2371

		/*
		 * Anything else is fatal, maybe with a core dump.
		 */
		current->flags |= PF_SIGNALED;
2372

L
Linus Torvalds 已提交
2373
		if (sig_kernel_coredump(signr)) {
2374
			if (print_fatal_signals)
2375
				print_fatal_signal(ksig->info.si_signo);
2376
			proc_coredump_connector(current);
L
Linus Torvalds 已提交
2377 2378 2379 2380 2381 2382 2383 2384
			/*
			 * 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.
			 */
2385
			do_coredump(&ksig->info);
L
Linus Torvalds 已提交
2386 2387 2388 2389 2390
		}

		/*
		 * Death signals, no core dump.
		 */
2391
		do_group_exit(ksig->info.si_signo);
L
Linus Torvalds 已提交
2392 2393
		/* NOTREACHED */
	}
2394
	spin_unlock_irq(&sighand->siglock);
2395 2396 2397

	ksig->sig = signr;
	return ksig->sig > 0;
L
Linus Torvalds 已提交
2398 2399
}

2400
/**
A
Al Viro 已提交
2401
 * signal_delivered - 
R
Richard Weinberger 已提交
2402
 * @ksig:		kernel signal struct
A
Al Viro 已提交
2403
 * @stepping:		nonzero if debugger single-step or block-step in use
2404
 *
2405
 * This function should be called when a signal has successfully been
R
Richard Weinberger 已提交
2406
 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
A
Al Viro 已提交
2407
 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
R
Richard Weinberger 已提交
2408
 * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2409
 */
R
Richard Weinberger 已提交
2410
static void signal_delivered(struct ksignal *ksig, int stepping)
2411 2412 2413
{
	sigset_t blocked;

2414 2415 2416 2417 2418 2419
	/* 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
2420 2421 2422
	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
		sigaddset(&blocked, ksig->sig);
2423
	set_current_blocked(&blocked);
2424
	tracehook_signal_handler(stepping);
2425 2426
}

A
Al Viro 已提交
2427 2428 2429 2430 2431
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
2432
		signal_delivered(ksig, stepping);
A
Al Viro 已提交
2433 2434
}

2435 2436
/*
 * It could be that complete_signal() picked us to notify about the
2437 2438
 * group-wide signal. Other threads should be notified now to take
 * the shared signals in @which since we will not.
2439
 */
2440
static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2441
{
2442
	sigset_t retarget;
2443 2444
	struct task_struct *t;

2445 2446 2447 2448
	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
	if (sigisemptyset(&retarget))
		return;

2449 2450
	t = tsk;
	while_each_thread(tsk, t) {
2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463
		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;
2464 2465 2466
	}
}

O
Oleg Nesterov 已提交
2467 2468 2469
void exit_signals(struct task_struct *tsk)
{
	int group_stop = 0;
2470
	sigset_t unblocked;
O
Oleg Nesterov 已提交
2471

2472 2473 2474 2475
	/*
	 * @tsk is about to have PF_EXITING set - lock out users which
	 * expect stable threadgroup.
	 */
2476
	cgroup_threadgroup_change_begin(tsk);
2477

2478 2479
	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
		tsk->flags |= PF_EXITING;
2480
		cgroup_threadgroup_change_end(tsk);
2481
		return;
O
Oleg Nesterov 已提交
2482 2483
	}

2484
	spin_lock_irq(&tsk->sighand->siglock);
O
Oleg Nesterov 已提交
2485 2486 2487 2488 2489
	/*
	 * From now this task is not visible for group-wide signals,
	 * see wants_signal(), do_signal_stop().
	 */
	tsk->flags |= PF_EXITING;
2490

2491
	cgroup_threadgroup_change_end(tsk);
2492

2493 2494 2495
	if (!signal_pending(tsk))
		goto out;

2496 2497 2498
	unblocked = tsk->blocked;
	signotset(&unblocked);
	retarget_shared_pending(tsk, &unblocked);
2499

2500
	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2501
	    task_participate_group_stop(tsk))
T
Tejun Heo 已提交
2502
		group_stop = CLD_STOPPED;
2503
out:
O
Oleg Nesterov 已提交
2504 2505
	spin_unlock_irq(&tsk->sighand->siglock);

2506 2507 2508 2509
	/*
	 * If group stop has completed, deliver the notification.  This
	 * should always go to the real parent of the group leader.
	 */
2510
	if (unlikely(group_stop)) {
O
Oleg Nesterov 已提交
2511
		read_lock(&tasklist_lock);
2512
		do_notify_parent_cldstop(tsk, false, group_stop);
O
Oleg Nesterov 已提交
2513 2514 2515 2516
		read_unlock(&tasklist_lock);
	}
}

L
Linus Torvalds 已提交
2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528
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.
 */

2529 2530 2531
/**
 *  sys_restart_syscall - restart a system call
 */
2532
SYSCALL_DEFINE0(restart_syscall)
L
Linus Torvalds 已提交
2533
{
2534
	struct restart_block *restart = &current->restart_block;
L
Linus Torvalds 已提交
2535 2536 2537 2538 2539 2540 2541 2542
	return restart->fn(restart);
}

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

2543 2544 2545 2546 2547
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. */
2548
		sigandnsets(&newblocked, newset, &current->blocked);
2549 2550 2551 2552 2553 2554
		retarget_shared_pending(tsk, &newblocked);
	}
	tsk->blocked = *newset;
	recalc_sigpending();
}

2555 2556 2557 2558 2559 2560
/**
 * 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
2561
 */
2562 2563 2564
void set_current_blocked(sigset_t *newset)
{
	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2565
	__set_current_blocked(newset);
2566 2567 2568
}

void __set_current_blocked(const sigset_t *newset)
2569 2570 2571
{
	struct task_struct *tsk = current;

2572 2573 2574 2575 2576 2577 2578
	/*
	 * 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;

2579
	spin_lock_irq(&tsk->sighand->siglock);
2580
	__set_task_blocked(tsk, newset);
2581 2582
	spin_unlock_irq(&tsk->sighand->siglock);
}
L
Linus Torvalds 已提交
2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593

/*
 * 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)
{
2594 2595
	struct task_struct *tsk = current;
	sigset_t newset;
L
Linus Torvalds 已提交
2596

2597
	/* Lockless, only current can change ->blocked, never from irq */
2598
	if (oldset)
2599
		*oldset = tsk->blocked;
2600

L
Linus Torvalds 已提交
2601 2602
	switch (how) {
	case SIG_BLOCK:
2603
		sigorsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2604 2605
		break;
	case SIG_UNBLOCK:
2606
		sigandnsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2607 2608
		break;
	case SIG_SETMASK:
2609
		newset = *set;
L
Linus Torvalds 已提交
2610 2611
		break;
	default:
2612
		return -EINVAL;
L
Linus Torvalds 已提交
2613
	}
2614

2615
	__set_current_blocked(&newset);
2616
	return 0;
L
Linus Torvalds 已提交
2617 2618
}

2619 2620 2621
/**
 *  sys_rt_sigprocmask - change the list of currently blocked signals
 *  @how: whether to add, remove, or set signals
R
Randy Dunlap 已提交
2622
 *  @nset: stores pending signals
2623 2624 2625
 *  @oset: previous value of signal mask if non-null
 *  @sigsetsize: size of sigset_t type
 */
2626
SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2627
		sigset_t __user *, oset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2628 2629
{
	sigset_t old_set, new_set;
2630
	int error;
L
Linus Torvalds 已提交
2631 2632 2633

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
2634
		return -EINVAL;
L
Linus Torvalds 已提交
2635

2636 2637 2638 2639 2640
	old_set = current->blocked;

	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2641 2642
		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

2643
		error = sigprocmask(how, &new_set, NULL);
L
Linus Torvalds 已提交
2644
		if (error)
2645 2646
			return error;
	}
L
Linus Torvalds 已提交
2647

2648 2649 2650
	if (oset) {
		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2651
	}
2652 2653

	return 0;
L
Linus Torvalds 已提交
2654 2655
}

A
Al Viro 已提交
2656 2657 2658
#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
2659
{
A
Al Viro 已提交
2660 2661 2662 2663 2664 2665 2666 2667 2668
	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) {
		sigset_t new_set;
		int error;
A
Al Viro 已提交
2669
		if (get_compat_sigset(&new_set, nset))
A
Al Viro 已提交
2670 2671 2672 2673 2674 2675 2676
			return -EFAULT;
		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

		error = sigprocmask(how, &new_set, NULL);
		if (error)
			return error;
	}
2677
	return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
A
Al Viro 已提交
2678 2679
}
#endif
L
Linus Torvalds 已提交
2680

2681
static int do_sigpending(sigset_t *set)
L
Linus Torvalds 已提交
2682 2683
{
	spin_lock_irq(&current->sighand->siglock);
A
Al Viro 已提交
2684
	sigorsets(set, &current->pending.signal,
L
Linus Torvalds 已提交
2685 2686 2687 2688
		  &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
2689 2690
	sigandsets(set, &current->blocked, set);
	return 0;
2691
}
L
Linus Torvalds 已提交
2692

2693 2694 2695
/**
 *  sys_rt_sigpending - examine a pending signal that has been raised
 *			while blocked
2696
 *  @uset: stores pending signals
2697 2698
 *  @sigsetsize: size of sigset_t type or larger
 */
A
Al Viro 已提交
2699
SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2700
{
A
Al Viro 已提交
2701
	sigset_t set;
2702 2703 2704 2705 2706 2707
	int err;

	if (sigsetsize > sizeof(*uset))
		return -EINVAL;

	err = do_sigpending(&set);
A
Al Viro 已提交
2708 2709 2710 2711 2712 2713 2714 2715
	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
2716
{
A
Al Viro 已提交
2717
	sigset_t set;
2718 2719 2720 2721 2722 2723
	int err;

	if (sigsetsize > sizeof(*uset))
		return -EINVAL;

	err = do_sigpending(&set);
2724 2725
	if (!err)
		err = put_compat_sigset(uset, &set, sigsetsize);
A
Al Viro 已提交
2726
	return err;
L
Linus Torvalds 已提交
2727
}
A
Al Viro 已提交
2728
#endif
L
Linus Torvalds 已提交
2729

2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741
enum siginfo_layout siginfo_layout(int sig, int si_code)
{
	enum siginfo_layout layout = SIL_KILL;
	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
		static const struct {
			unsigned char limit, layout;
		} filter[] = {
			[SIGILL]  = { NSIGILL,  SIL_FAULT },
			[SIGFPE]  = { NSIGFPE,  SIL_FAULT },
			[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
			[SIGBUS]  = { NSIGBUS,  SIL_FAULT },
			[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
2742
#if defined(SIGEMT) && defined(NSIGEMT)
2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767
			[SIGEMT]  = { NSIGEMT,  SIL_FAULT },
#endif
			[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
			[SIGPOLL] = { NSIGPOLL, SIL_POLL },
			[SIGSYS]  = { NSIGSYS,  SIL_SYS },
		};
		if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit))
			layout = filter[sig].layout;
		else if (si_code <= NSIGPOLL)
			layout = SIL_POLL;
	} else {
		if (si_code == SI_TIMER)
			layout = SIL_TIMER;
		else if (si_code == SI_SIGIO)
			layout = SIL_POLL;
		else if (si_code < 0)
			layout = SIL_RT;
		/* Tests to support buggy kernel ABIs */
#ifdef TRAP_FIXME
		if ((sig == SIGTRAP) && (si_code == TRAP_FIXME))
			layout = SIL_FAULT;
#endif
#ifdef FPE_FIXME
		if ((sig == SIGFPE) && (si_code == FPE_FIXME))
			layout = SIL_FAULT;
2768 2769 2770 2771
#endif
#ifdef BUS_FIXME
		if ((sig == SIGBUS) && (si_code == BUS_FIXME))
			layout = SIL_FAULT;
2772 2773 2774 2775 2776
#endif
	}
	return layout;
}

A
Al Viro 已提交
2777
int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
L
Linus Torvalds 已提交
2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788
{
	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.
2789 2790
	 * Please remember to update the signalfd_copyinfo() function
	 * inside fs/signalfd.c too, in case siginfo_t changes.
L
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2791 2792 2793 2794 2795 2796
	 * 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);
2797 2798 2799
	err |= __put_user(from->si_code, &to->si_code);
	switch (siginfo_layout(from->si_signo, from->si_code)) {
	case SIL_KILL:
L
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2800 2801 2802
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		break;
2803 2804
	case SIL_TIMER:
		/* Unreached SI_TIMER is negative */
L
Linus Torvalds 已提交
2805
		break;
2806
	case SIL_POLL:
L
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2807 2808 2809
		err |= __put_user(from->si_band, &to->si_band);
		err |= __put_user(from->si_fd, &to->si_fd);
		break;
2810
	case SIL_FAULT:
L
Linus Torvalds 已提交
2811 2812 2813
		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
2814
#endif
2815 2816 2817 2818 2819
#ifdef __ia64__
		err |= __put_user(from->si_imm, &to->si_imm);
		err |= __put_user(from->si_flags, &to->si_flags);
		err |= __put_user(from->si_isr, &to->si_isr);
#endif
2820
		/*
A
Andi Kleen 已提交
2821
		 * Other callers might not initialize the si_lsb field,
2822
		 * so check explicitly for the right codes here.
A
Andi Kleen 已提交
2823
		 */
2824 2825 2826 2827 2828 2829
#ifdef BUS_MCEERR_AR
		if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AR)
			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
#endif
#ifdef BUS_MCEERR_AO
		if (from->si_signo == SIGBUS && from->si_code == BUS_MCEERR_AO)
A
Andi Kleen 已提交
2830
			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2831 2832
#endif
#ifdef SEGV_BNDERR
2833 2834 2835 2836
		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);
		}
2837 2838 2839 2840
#endif
#ifdef SEGV_PKUERR
		if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
			err |= __put_user(from->si_pkey, &to->si_pkey);
L
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2841 2842
#endif
		break;
2843
	case SIL_CHLD:
L
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2844 2845 2846 2847 2848 2849
		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;
2850
	case SIL_RT:
L
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2851 2852 2853 2854
		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;
2855
	case SIL_SYS:
2856 2857 2858 2859
		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;
L
Linus Torvalds 已提交
2860 2861 2862 2863
	}
	return err;
}

2864
#ifdef CONFIG_COMPAT
2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954
int copy_siginfo_to_user32(struct compat_siginfo __user *to,
			   const struct siginfo *from)
#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
{
	return __copy_siginfo_to_user32(to, from, in_x32_syscall());
}
int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
			     const struct siginfo *from, bool x32_ABI)
#endif
{
	struct compat_siginfo new;
	memset(&new, 0, sizeof(new));

	new.si_signo = from->si_signo;
	new.si_errno = from->si_errno;
	new.si_code  = from->si_code;
	switch(siginfo_layout(from->si_signo, from->si_code)) {
	case SIL_KILL:
		new.si_pid = from->si_pid;
		new.si_uid = from->si_uid;
		break;
	case SIL_TIMER:
		new.si_tid     = from->si_tid;
		new.si_overrun = from->si_overrun;
		new.si_int     = from->si_int;
		break;
	case SIL_POLL:
		new.si_band = from->si_band;
		new.si_fd   = from->si_fd;
		break;
	case SIL_FAULT:
		new.si_addr = ptr_to_compat(from->si_addr);
#ifdef __ARCH_SI_TRAPNO
		new.si_trapno = from->si_trapno;
#endif
#ifdef BUS_MCEERR_AR
		if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AR))
			new.si_addr_lsb = from->si_addr_lsb;
#endif
#ifdef BUS_MCEERR_AO
		if ((from->si_signo == SIGBUS) && (from->si_code == BUS_MCEERR_AO))
			new.si_addr_lsb = from->si_addr_lsb;
#endif
#ifdef SEGV_BNDERR
		if ((from->si_signo == SIGSEGV) &&
		    (from->si_code == SEGV_BNDERR)) {
			new.si_lower = ptr_to_compat(from->si_lower);
			new.si_upper = ptr_to_compat(from->si_upper);
		}
#endif
#ifdef SEGV_PKUERR
		if ((from->si_signo == SIGSEGV) &&
		    (from->si_code == SEGV_PKUERR))
			new.si_pkey = from->si_pkey;
#endif

		break;
	case SIL_CHLD:
		new.si_pid    = from->si_pid;
		new.si_uid    = from->si_uid;
		new.si_status = from->si_status;
#ifdef CONFIG_X86_X32_ABI
		if (x32_ABI) {
			new._sifields._sigchld_x32._utime = from->si_utime;
			new._sifields._sigchld_x32._stime = from->si_stime;
		} else
#endif
		{
			new.si_utime = from->si_utime;
			new.si_stime = from->si_stime;
		}
		break;
	case SIL_RT:
		new.si_pid = from->si_pid;
		new.si_uid = from->si_uid;
		new.si_int = from->si_int;
		break;
	case SIL_SYS:
		new.si_call_addr = ptr_to_compat(from->si_call_addr);
		new.si_syscall   = from->si_syscall;
		new.si_arch      = from->si_arch;
		break;
	}

	if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
		return -EFAULT;

	return 0;
}

2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034
int copy_siginfo_from_user32(struct siginfo *to,
			     const struct compat_siginfo __user *ufrom)
{
	struct compat_siginfo from;

	if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo)))
		return -EFAULT;

	clear_siginfo(to);
	to->si_signo = from.si_signo;
	to->si_errno = from.si_errno;
	to->si_code  = from.si_code;
	switch(siginfo_layout(from.si_signo, from.si_code)) {
	case SIL_KILL:
		to->si_pid = from.si_pid;
		to->si_uid = from.si_uid;
		break;
	case SIL_TIMER:
		to->si_tid     = from.si_tid;
		to->si_overrun = from.si_overrun;
		to->si_int     = from.si_int;
		break;
	case SIL_POLL:
		to->si_band = from.si_band;
		to->si_fd   = from.si_fd;
		break;
	case SIL_FAULT:
		to->si_addr = compat_ptr(from.si_addr);
#ifdef __ARCH_SI_TRAPNO
		to->si_trapno = from.si_trapno;
#endif
#ifdef BUS_MCEERR_AR
		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AR))
			to->si_addr_lsb = from.si_addr_lsb;
#endif
#ifdef BUS_MCEER_AO
		if ((from.si_signo == SIGBUS) && (from.si_code == BUS_MCEERR_AO))
			to->si_addr_lsb = from.si_addr_lsb;
#endif
#ifdef SEGV_BNDERR
		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) {
			to->si_lower = compat_ptr(from.si_lower);
			to->si_upper = compat_ptr(from.si_upper);
		}
#endif
#ifdef SEGV_PKUERR
		if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR))
			to->si_pkey = from.si_pkey;
#endif
		break;
	case SIL_CHLD:
		to->si_pid    = from.si_pid;
		to->si_uid    = from.si_uid;
		to->si_status = from.si_status;
#ifdef CONFIG_X86_X32_ABI
		if (in_x32_syscall()) {
			to->si_utime = from._sifields._sigchld_x32._utime;
			to->si_stime = from._sifields._sigchld_x32._stime;
		} else
#endif
		{
			to->si_utime = from.si_utime;
			to->si_stime = from.si_stime;
		}
		break;
	case SIL_RT:
		to->si_pid = from.si_pid;
		to->si_uid = from.si_uid;
		to->si_int = from.si_int;
		break;
	case SIL_SYS:
		to->si_call_addr = compat_ptr(from.si_call_addr);
		to->si_syscall   = from.si_syscall;
		to->si_arch      = from.si_arch;
		break;
	}
	return 0;
}
#endif /* CONFIG_COMPAT */

3035 3036 3037 3038 3039 3040
/**
 *  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
 */
3041
static int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
3042
		    const struct timespec *ts)
3043
{
T
Thomas Gleixner 已提交
3044
	ktime_t *to = NULL, timeout = KTIME_MAX;
3045 3046
	struct task_struct *tsk = current;
	sigset_t mask = *which;
3047
	int sig, ret = 0;
3048 3049 3050 3051

	if (ts) {
		if (!timespec_valid(ts))
			return -EINVAL;
3052 3053
		timeout = timespec_to_ktime(*ts);
		to = &timeout;
3054 3055 3056 3057 3058 3059 3060 3061 3062 3063
	}

	/*
	 * 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
3064
	if (!sig && timeout) {
3065 3066 3067
		/*
		 * None ready, temporarily unblock those we're interested
		 * while we are sleeping in so that we'll be awakened when
3068 3069
		 * they arrive. Unblocking is always fine, we can avoid
		 * set_current_blocked().
3070 3071 3072 3073 3074 3075
		 */
		tsk->real_blocked = tsk->blocked;
		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
		recalc_sigpending();
		spin_unlock_irq(&tsk->sighand->siglock);

3076 3077 3078
		__set_current_state(TASK_INTERRUPTIBLE);
		ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
							 HRTIMER_MODE_REL);
3079
		spin_lock_irq(&tsk->sighand->siglock);
3080
		__set_task_blocked(tsk, &tsk->real_blocked);
3081
		sigemptyset(&tsk->real_blocked);
3082
		sig = dequeue_signal(tsk, &mask, info);
3083 3084 3085 3086 3087
	}
	spin_unlock_irq(&tsk->sighand->siglock);

	if (sig)
		return sig;
3088
	return ret ? -EINTR : -EAGAIN;
3089 3090
}

3091 3092 3093 3094 3095 3096 3097 3098
/**
 *  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
 */
3099 3100 3101
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
3102 3103 3104 3105
{
	sigset_t these;
	struct timespec ts;
	siginfo_t info;
3106
	int ret;
L
Linus Torvalds 已提交
3107 3108 3109 3110 3111 3112 3113

	/* 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;
3114

L
Linus Torvalds 已提交
3115 3116 3117 3118 3119
	if (uts) {
		if (copy_from_user(&ts, uts, sizeof(ts)))
			return -EFAULT;
	}

3120
	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
L
Linus Torvalds 已提交
3121

3122 3123 3124
	if (ret > 0 && uinfo) {
		if (copy_siginfo_to_user(uinfo, &info))
			ret = -EFAULT;
L
Linus Torvalds 已提交
3125 3126 3127 3128 3129
	}

	return ret;
}

3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese,
		struct compat_siginfo __user *, uinfo,
		struct compat_timespec __user *, uts, compat_size_t, sigsetsize)
{
	sigset_t s;
	struct timespec t;
	siginfo_t info;
	long ret;

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

A
Al Viro 已提交
3143
	if (get_compat_sigset(&s, uthese))
3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161
		return -EFAULT;

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

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

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

	return ret;
}
#endif

3162 3163 3164 3165 3166
/**
 *  sys_kill - send a signal to a process
 *  @pid: the PID of the process
 *  @sig: signal to be sent
 */
3167
SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
3168 3169 3170
{
	struct siginfo info;

3171
	clear_siginfo(&info);
L
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3172 3173 3174
	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_USER;
3175
	info.si_pid = task_tgid_vnr(current);
3176
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
3177 3178 3179 3180

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

T
Thomas Gleixner 已提交
3181 3182
static int
do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
L
Linus Torvalds 已提交
3183 3184
{
	struct task_struct *p;
T
Thomas Gleixner 已提交
3185
	int error = -ESRCH;
L
Linus Torvalds 已提交
3186

3187
	rcu_read_lock();
3188
	p = find_task_by_vpid(pid);
3189
	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
T
Thomas Gleixner 已提交
3190
		error = check_kill_permission(sig, info, p);
L
Linus Torvalds 已提交
3191 3192 3193 3194
		/*
		 * The null signal is a permissions and process existence
		 * probe.  No signal is actually delivered.
		 */
3195 3196 3197 3198 3199 3200 3201 3202 3203
		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
3204 3205
		}
	}
3206
	rcu_read_unlock();
3207

L
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3208 3209 3210
	return error;
}

T
Thomas Gleixner 已提交
3211 3212
static int do_tkill(pid_t tgid, pid_t pid, int sig)
{
3213
	struct siginfo info;
T
Thomas Gleixner 已提交
3214

3215
	clear_siginfo(&info);
T
Thomas Gleixner 已提交
3216 3217 3218 3219
	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_TKILL;
	info.si_pid = task_tgid_vnr(current);
3220
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
T
Thomas Gleixner 已提交
3221 3222 3223 3224

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

3225 3226 3227 3228 3229 3230
/**
 *  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
 *
3231
 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
3232 3233 3234
 *  exists but it's not belonging to the target process anymore. This
 *  method solves the problem of threads exiting and PIDs getting reused.
 */
3235
SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
3236 3237 3238 3239 3240 3241 3242 3243
{
	/* This is only valid for single tasks */
	if (pid <= 0 || tgid <= 0)
		return -EINVAL;

	return do_tkill(tgid, pid, sig);
}

3244 3245 3246 3247 3248
/**
 *  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
3249 3250
 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
 */
3251
SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
3252 3253 3254 3255 3256
{
	/* This is only valid for single tasks */
	if (pid <= 0)
		return -EINVAL;

3257
	return do_tkill(0, pid, sig);
L
Linus Torvalds 已提交
3258 3259
}

A
Al Viro 已提交
3260 3261 3262 3263 3264
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.
	 */
3265
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
3266
	    (task_pid_vnr(current) != pid))
A
Al Viro 已提交
3267
		return -EPERM;
3268

A
Al Viro 已提交
3269 3270 3271 3272 3273 3274
	info->si_signo = sig;

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

3275 3276 3277 3278 3279 3280
/**
 *  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
 */
3281 3282
SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
		siginfo_t __user *, uinfo)
L
Linus Torvalds 已提交
3283 3284 3285 3286
{
	siginfo_t info;
	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
		return -EFAULT;
A
Al Viro 已提交
3287 3288
	return do_rt_sigqueueinfo(pid, sig, &info);
}
L
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3289

A
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3290 3291 3292 3293 3294 3295
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
3296
	siginfo_t info;
A
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3297 3298 3299 3300
	int ret = copy_siginfo_from_user32(&info, uinfo);
	if (unlikely(ret))
		return ret;
	return do_rt_sigqueueinfo(pid, sig, &info);
L
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3301
}
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3302
#endif
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3303

3304
static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
3305 3306 3307 3308 3309 3310
{
	/* 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.
3311 3312
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
3313 3314
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
	    (task_pid_vnr(current) != pid))
3315
		return -EPERM;
3316

3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332
	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);
}

3333 3334 3335 3336 3337 3338 3339
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
			compat_pid_t, tgid,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
3340
	siginfo_t info;
3341 3342 3343 3344 3345 3346 3347

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

3348
/*
3349
 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3350
 */
3351
void kernel_sigaction(int sig, __sighandler_t action)
3352
{
3353
	spin_lock_irq(&current->sighand->siglock);
3354 3355 3356
	current->sighand->action[sig - 1].sa.sa_handler = action;
	if (action == SIG_IGN) {
		sigset_t mask;
3357

3358 3359
		sigemptyset(&mask);
		sigaddset(&mask, sig);
3360

3361 3362 3363 3364
		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
		flush_sigqueue_mask(&mask, &current->pending);
		recalc_sigpending();
	}
3365 3366
	spin_unlock_irq(&current->sighand->siglock);
}
3367
EXPORT_SYMBOL(kernel_sigaction);
3368

3369 3370 3371 3372 3373
void __weak sigaction_compat_abi(struct k_sigaction *act,
		struct k_sigaction *oact)
{
}

3374
int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
L
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3375
{
3376
	struct task_struct *p = current, *t;
L
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3377
	struct k_sigaction *k;
3378
	sigset_t mask;
L
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3379

3380
	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
L
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3381 3382
		return -EINVAL;

3383
	k = &p->sighand->action[sig-1];
L
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3384

3385
	spin_lock_irq(&p->sighand->siglock);
L
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3386 3387 3388
	if (oact)
		*oact = *k;

3389 3390
	sigaction_compat_abi(act, oact);

L
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3391
	if (act) {
3392 3393
		sigdelsetmask(&act->sa.sa_mask,
			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3394
		*k = *act;
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3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405
		/*
		 * 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"
		 */
3406
		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3407 3408
			sigemptyset(&mask);
			sigaddset(&mask, sig);
3409 3410
			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
			for_each_thread(p, t)
3411
				flush_sigqueue_mask(&mask, &t->pending);
L
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3412 3413 3414
		}
	}

3415
	spin_unlock_irq(&p->sighand->siglock);
L
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3416 3417 3418
	return 0;
}

3419
static int
3420
do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
L
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3421
{
3422
	struct task_struct *t = current;
L
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3423

3424 3425 3426 3427 3428 3429 3430
	if (oss) {
		memset(oss, 0, sizeof(stack_t));
		oss->ss_sp = (void __user *) t->sas_ss_sp;
		oss->ss_size = t->sas_ss_size;
		oss->ss_flags = sas_ss_flags(sp) |
			(current->sas_ss_flags & SS_FLAG_BITS);
	}
L
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3431

3432 3433 3434 3435
	if (ss) {
		void __user *ss_sp = ss->ss_sp;
		size_t ss_size = ss->ss_size;
		unsigned ss_flags = ss->ss_flags;
3436
		int ss_mode;
L
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3437

3438 3439
		if (unlikely(on_sig_stack(sp)))
			return -EPERM;
L
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3440

3441
		ss_mode = ss_flags & ~SS_FLAG_BITS;
3442 3443 3444
		if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
				ss_mode != 0))
			return -EINVAL;
L
Linus Torvalds 已提交
3445

3446
		if (ss_mode == SS_DISABLE) {
L
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3447 3448 3449
			ss_size = 0;
			ss_sp = NULL;
		} else {
3450 3451
			if (unlikely(ss_size < MINSIGSTKSZ))
				return -ENOMEM;
L
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3452 3453
		}

3454 3455 3456
		t->sas_ss_sp = (unsigned long) ss_sp;
		t->sas_ss_size = ss_size;
		t->sas_ss_flags = ss_flags;
L
Linus Torvalds 已提交
3457
	}
3458
	return 0;
L
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3459
}
3460

3461 3462
SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
{
3463 3464 3465 3466 3467 3468 3469 3470 3471
	stack_t new, old;
	int err;
	if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
		return -EFAULT;
	err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
			      current_user_stack_pointer());
	if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
		err = -EFAULT;
	return err;
3472
}
L
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3473

A
Al Viro 已提交
3474 3475
int restore_altstack(const stack_t __user *uss)
{
3476 3477 3478 3479
	stack_t new;
	if (copy_from_user(&new, uss, sizeof(stack_t)))
		return -EFAULT;
	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
A
Al Viro 已提交
3480
	/* squash all but EFAULT for now */
3481
	return 0;
A
Al Viro 已提交
3482 3483
}

3484 3485 3486
int __save_altstack(stack_t __user *uss, unsigned long sp)
{
	struct task_struct *t = current;
3487 3488
	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3489
		__put_user(t->sas_ss_size, &uss->ss_size);
3490 3491 3492 3493 3494
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3495 3496
}

A
Al Viro 已提交
3497
#ifdef CONFIG_COMPAT
3498 3499 3500
COMPAT_SYSCALL_DEFINE2(sigaltstack,
			const compat_stack_t __user *, uss_ptr,
			compat_stack_t __user *, uoss_ptr)
A
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3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512
{
	stack_t uss, uoss;
	int ret;

	if (uss_ptr) {
		compat_stack_t uss32;
		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
			return -EFAULT;
		uss.ss_sp = compat_ptr(uss32.ss_sp);
		uss.ss_flags = uss32.ss_flags;
		uss.ss_size = uss32.ss_size;
	}
3513
	ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
A
Al Viro 已提交
3514 3515
			     compat_user_stack_pointer());
	if (ret >= 0 && uoss_ptr)  {
3516 3517 3518 3519 3520 3521
		compat_stack_t old;
		memset(&old, 0, sizeof(old));
		old.ss_sp = ptr_to_compat(uoss.ss_sp);
		old.ss_flags = uoss.ss_flags;
		old.ss_size = uoss.ss_size;
		if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
A
Al Viro 已提交
3522 3523 3524 3525 3526 3527 3528 3529 3530 3531 3532
			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;
}
3533 3534 3535

int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
{
3536
	int err;
3537
	struct task_struct *t = current;
3538 3539 3540
	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
			 &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3541
		__put_user(t->sas_ss_size, &uss->ss_size);
3542 3543 3544 3545 3546
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3547
}
A
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3548
#endif
L
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3549 3550 3551

#ifdef __ARCH_WANT_SYS_SIGPENDING

3552 3553 3554 3555
/**
 *  sys_sigpending - examine pending signals
 *  @set: where mask of pending signal is returned
 */
3556
SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
L
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3557
{
A
Al Viro 已提交
3558
	return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 
L
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3559 3560
}

A
Al Viro 已提交
3561 3562 3563 3564
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
{
	sigset_t set;
3565
	int err = do_sigpending(&set);
3566 3567
	if (!err)
		err = put_user(set.sig[0], set32);
A
Al Viro 已提交
3568 3569 3570 3571
	return err;
}
#endif

L
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3572 3573 3574
#endif

#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3575 3576 3577
/**
 *  sys_sigprocmask - examine and change blocked signals
 *  @how: whether to add, remove, or set signals
3578
 *  @nset: signals to add or remove (if non-null)
3579 3580
 *  @oset: previous value of signal mask if non-null
 *
3581 3582 3583
 * Some platforms have their own version with special arguments;
 * others support only sys_rt_sigprocmask.
 */
L
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3584

3585
SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3586
		old_sigset_t __user *, oset)
L
Linus Torvalds 已提交
3587 3588
{
	old_sigset_t old_set, new_set;
3589
	sigset_t new_blocked;
L
Linus Torvalds 已提交
3590

3591
	old_set = current->blocked.sig[0];
L
Linus Torvalds 已提交
3592

3593 3594 3595
	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(*nset)))
			return -EFAULT;
L
Linus Torvalds 已提交
3596

3597
		new_blocked = current->blocked;
L
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3598 3599 3600

		switch (how) {
		case SIG_BLOCK:
3601
			sigaddsetmask(&new_blocked, new_set);
L
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3602 3603
			break;
		case SIG_UNBLOCK:
3604
			sigdelsetmask(&new_blocked, new_set);
L
Linus Torvalds 已提交
3605 3606
			break;
		case SIG_SETMASK:
3607
			new_blocked.sig[0] = new_set;
L
Linus Torvalds 已提交
3608
			break;
3609 3610
		default:
			return -EINVAL;
L
Linus Torvalds 已提交
3611 3612
		}

3613
		set_current_blocked(&new_blocked);
3614 3615 3616
	}

	if (oset) {
L
Linus Torvalds 已提交
3617
		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3618
			return -EFAULT;
L
Linus Torvalds 已提交
3619
	}
3620 3621

	return 0;
L
Linus Torvalds 已提交
3622 3623 3624
}
#endif /* __ARCH_WANT_SYS_SIGPROCMASK */

3625
#ifndef CONFIG_ODD_RT_SIGACTION
3626 3627 3628
/**
 *  sys_rt_sigaction - alter an action taken by a process
 *  @sig: signal to be sent
3629 3630
 *  @act: new sigaction
 *  @oact: used to save the previous sigaction
3631 3632
 *  @sigsetsize: size of sigset_t type
 */
3633 3634 3635 3636
SYSCALL_DEFINE4(rt_sigaction, int, sig,
		const struct sigaction __user *, act,
		struct sigaction __user *, oact,
		size_t, sigsetsize)
L
Linus Torvalds 已提交
3637 3638 3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658
{
	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
Al Viro 已提交
3659 3660 3661 3662 3663 3664 3665 3666 3667 3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682
#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;
#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
A
Al Viro 已提交
3683
		ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask);
3684
		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
A
Al Viro 已提交
3685 3686 3687 3688 3689 3690 3691 3692
		if (ret)
			return -EFAULT;
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
	if (!ret && oact) {
		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
			       &oact->sa_handler);
3693 3694
		ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
					 sizeof(oact->sa_mask));
3695
		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
A
Al Viro 已提交
3696 3697 3698 3699 3700 3701 3702 3703
#ifdef __ARCH_HAS_SA_RESTORER
		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
				&oact->sa_restorer);
#endif
	}
	return ret;
}
#endif
3704
#endif /* !CONFIG_ODD_RT_SIGACTION */
L
Linus Torvalds 已提交
3705

3706 3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722 3723 3724 3725 3726 3727 3728 3729 3730 3731 3732 3733 3734 3735 3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760 3761 3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 3782
#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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3783

3784
#ifdef CONFIG_SGETMASK_SYSCALL
L
Linus Torvalds 已提交
3785 3786 3787 3788

/*
 * For backwards compatibility.  Functionality superseded by sigprocmask.
 */
3789
SYSCALL_DEFINE0(sgetmask)
L
Linus Torvalds 已提交
3790 3791 3792 3793 3794
{
	/* SMP safe */
	return current->blocked.sig[0];
}

3795
SYSCALL_DEFINE1(ssetmask, int, newmask)
L
Linus Torvalds 已提交
3796
{
3797 3798
	int old = current->blocked.sig[0];
	sigset_t newset;
L
Linus Torvalds 已提交
3799

3800
	siginitset(&newset, newmask);
3801
	set_current_blocked(&newset);
L
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3802 3803 3804

	return old;
}
3805
#endif /* CONFIG_SGETMASK_SYSCALL */
L
Linus Torvalds 已提交
3806 3807 3808 3809 3810

#ifdef __ARCH_WANT_SYS_SIGNAL
/*
 * For backwards compatibility.  Functionality superseded by sigaction.
 */
3811
SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
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{
	struct k_sigaction new_sa, old_sa;
	int ret;

	new_sa.sa.sa_handler = handler;
	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3818
	sigemptyset(&new_sa.sa.sa_mask);
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	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

3828
SYSCALL_DEFINE0(pause)
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{
3830
	while (!signal_pending(current)) {
3831
		__set_current_state(TASK_INTERRUPTIBLE);
3832 3833
		schedule();
	}
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	return -ERESTARTNOHAND;
}

#endif

3839
static int sigsuspend(sigset_t *set)
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{
	current->saved_sigmask = current->blocked;
	set_current_blocked(set);

3844 3845 3846 3847
	while (!signal_pending(current)) {
		__set_current_state(TASK_INTERRUPTIBLE);
		schedule();
	}
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	set_restore_sigmask();
	return -ERESTARTNOHAND;
}

3852 3853 3854 3855 3856 3857
/**
 *  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
 */
3858
SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3859 3860 3861 3862 3863 3864 3865 3866 3867
{
	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;
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	return sigsuspend(&newset);
3869
}
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#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
{
	sigset_t newset;

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

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	if (get_compat_sigset(&newset, unewset))
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		return -EFAULT;
	return sigsuspend(&newset);
}
#endif
3885

3886 3887 3888 3889 3890 3891 3892 3893 3894 3895 3896 3897 3898 3899 3900 3901
#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
3902

3903
__weak const char *arch_vma_name(struct vm_area_struct *vma)
3904 3905 3906 3907
{
	return NULL;
}

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void __init signals_init(void)
{
3910 3911 3912
	/* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
	BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
		!= offsetof(struct siginfo, _sifields._pad));
3913
	BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE);
3914

3915
	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
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}
3917 3918 3919 3920

#ifdef CONFIG_KGDB_KDB
#include <linux/kdb.h>
/*
3921
 * kdb_send_sig - Allows kdb to send signals without exposing
3922 3923 3924 3925
 * signal internals.  This function checks if the required locks are
 * available before calling the main signal code, to avoid kdb
 * deadlocks.
 */
3926
void kdb_send_sig(struct task_struct *t, int sig)
3927 3928
{
	static struct task_struct *kdb_prev_t;
3929
	int new_t, ret;
3930 3931 3932 3933 3934 3935 3936 3937 3938
	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;
	}
	new_t = kdb_prev_t != t;
	kdb_prev_t = t;
	if (t->state != TASK_RUNNING && new_t) {
3939
		spin_unlock(&t->sighand->siglock);
3940 3941 3942 3943 3944 3945 3946 3947
		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;
	}
3948 3949 3950
	ret = send_signal(sig, SEND_SIG_PRIV, t, false);
	spin_unlock(&t->sighand->siglock);
	if (ret)
3951 3952 3953 3954 3955 3956
		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 */