signal.c 86.2 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>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#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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#define CREATE_TRACE_POINTS
#include <trace/events/signal.h>
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#include <asm/param.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/siginfo.h>
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#include <asm/cacheflush.h>
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#include "audit.h"	/* audit_signal_info() */
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/*
 * SLAB caches for signal bits.
 */

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static struct kmem_cache *sigqueue_cachep;
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int print_fatal_signals __read_mostly;

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

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

	return sig_handler_ignored(handler, sig);
}

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

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

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

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

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

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

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

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

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

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

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

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

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}

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

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

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

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

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

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

	if (!print_fatal_signals)
		return;

	if (!__ratelimit(&ratelimit_state))
		return;

	printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
				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.
 */
bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
{
	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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		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 int 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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		sig->flags = SIGNAL_STOP_STOPPED;
		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);
	}
}

/*
 * Flush all pending signals for a task.
 */
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void __flush_signals(struct task_struct *t)
{
	clear_tsk_thread_flag(t, TIF_SIGPENDING);
	flush_sigqueue(&t->pending);
	flush_sigqueue(&t->signal->shared_pending);
}

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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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	__flush_signals(t);
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	spin_unlock_irqrestore(&t->sighand->siglock, flags);
}

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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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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;
		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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/*
 * Notify the system that a driver wants to block all signals for this
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 * process, and wants to be notified if any signals at all were to be
 * sent/acted upon.  If the notifier routine returns non-zero, then the
 * signal will be acted upon after all.  If the notifier routine returns 0,
 * then then signal will be blocked.  Only one block per process is
 * allowed.  priv is a pointer to private data that the notifier routine
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 * can use to determine if the signal should be blocked or not.
 */
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void
block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
{
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	current->notifier_mask = mask;
	current->notifier_data = priv;
	current->notifier = notifier;
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
}

/* Notify the system that blocking has ended. */

void
unblock_all_signals(void)
{
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	current->notifier = NULL;
	current->notifier_data = NULL;
	recalc_sigpending();
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
}

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

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

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

static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
			siginfo_t *info)
{
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	int sig = next_signal(pending, mask);
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	if (sig) {
		if (current->notifier) {
			if (sigismember(current->notifier_mask, sig)) {
				if (!(current->notifier)(current->notifier_data)) {
					clear_thread_flag(TIF_SIGPENDING);
					return 0;
				}
			}
		}

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		collect_signal(sig, pending, info);
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	}

	return sig;
}

/*
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 * Dequeue a signal and return the element to the caller, which is
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 * expected to free it.
 *
 * All callers have to hold the siglock.
 */
int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
{
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	int signr;
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	/* We only dequeue private signals from ourselves, we don't let
	 * signalfd steal them
	 */
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	signr = __dequeue_signal(&tsk->pending, mask, info);
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	if (!signr) {
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		signr = __dequeue_signal(&tsk->signal->shared_pending,
					 mask, info);
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		/*
		 * 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) &&
			    tsk->signal->it_real_incr.tv64 != 0) {
				hrtimer_forward(tmr, tmr->base->get_time(),
						tsk->signal->it_real_incr);
				hrtimer_restart(tmr);
			}
		}
	}
636

D
Davide Libenzi 已提交
637
	recalc_sigpending();
638 639 640 641
	if (!signr)
		return 0;

	if (unlikely(sig_kernel_stop(signr))) {
642 643 644 645 646 647 648 649 650 651 652 653
		/*
		 * 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.
		 */
654
		current->jobctl |= JOBCTL_STOP_DEQUEUED;
655
	}
656
	if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
L
Linus Torvalds 已提交
657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687
		/*
		 * Release the siglock to ensure proper locking order
		 * of timer locks outside of siglocks.  Note, we leave
		 * irqs disabled here, since the posix-timers code is
		 * about to disable them again anyway.
		 */
		spin_unlock(&tsk->sighand->siglock);
		do_schedule_next_timer(info);
		spin_lock(&tsk->sighand->siglock);
	}
	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
 */
void signal_wake_up(struct task_struct *t, int resume)
{
	unsigned int mask;

	set_tsk_thread_flag(t, TIF_SIGPENDING);

	/*
M
Matthew Wilcox 已提交
688 689
	 * For SIGKILL, we want to wake it up in the stopped/traced/killable
	 * case. We don't check t->state here because there is a race with it
L
Linus Torvalds 已提交
690 691 692 693 694 695
	 * 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.
	 */
	mask = TASK_INTERRUPTIBLE;
	if (resume)
M
Matthew Wilcox 已提交
696
		mask |= TASK_WAKEKILL;
L
Linus Torvalds 已提交
697 698 699 700
	if (!wake_up_state(t, mask))
		kick_process(t);
}

701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718
/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 *
 * This version takes a sigset mask and looks at all signals,
 * not just those in the first mask word.
 */
static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
{
	struct sigqueue *q, *n;
	sigset_t m;

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

719
	sigandnsets(&s->signal, &s->signal, mask);
720 721 722 723 724 725 726 727
	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
728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751
/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 */
static int rm_from_queue(unsigned long mask, struct sigpending *s)
{
	struct sigqueue *q, *n;

	if (!sigtestsetmask(&s->signal, mask))
		return 0;

	sigdelsetmask(&s->signal, mask);
	list_for_each_entry_safe(q, n, &s->list, list) {
		if (q->info.si_signo < SIGRTMIN &&
		    (mask & sigmask(q->info.si_signo))) {
			list_del_init(&q->list);
			__sigqueue_free(q);
		}
	}
	return 1;
}

752 753 754 755 756 757 758 759 760 761 762
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));
}

763 764 765 766 767 768 769 770
/*
 * 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);

771 772 773 774
	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))
775 776
		return 1;

777
	if (ns_capable(tcred->user_ns, CAP_KILL))
778 779 780 781 782
		return 1;

	return 0;
}

L
Linus Torvalds 已提交
783 784
/*
 * Bad permissions for sending the signal
785
 * - the caller must hold the RCU read lock
L
Linus Torvalds 已提交
786 787 788 789
 */
static int check_kill_permission(int sig, struct siginfo *info,
				 struct task_struct *t)
{
790
	struct pid *sid;
791 792
	int error;

793
	if (!valid_signal(sig))
794 795
		return -EINVAL;

796
	if (!si_fromuser(info))
797
		return 0;
A
Amy Griffis 已提交
798

799 800
	error = audit_signal_info(sig, t); /* Let audit system see the signal */
	if (error)
L
Linus Torvalds 已提交
801
		return error;
802

803
	if (!same_thread_group(current, t) &&
804
	    !kill_ok_by_cred(t)) {
805 806 807 808 809 810 811 812 813 814 815 816 817
		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;
		}
	}
818

A
Amy Griffis 已提交
819
	return security_task_kill(t, info, sig, 0);
L
Linus Torvalds 已提交
820 821
}

822 823 824 825 826 827 828 829
/**
 * 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
830 831 832 833 834
 * 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.
835 836 837 838 839 840 841 842 843 844
 *
 * 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);
T
Tejun Heo 已提交
845
	signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
846 847
}

L
Linus Torvalds 已提交
848
/*
849 850
 * 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
851 852
 * time regardless of blocking, ignoring, or handling.  This does the
 * actual continuing for SIGCONT, but not the actual stopping for stop
853 854 855 856
 * 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
857
 */
858
static int prepare_signal(int sig, struct task_struct *p, bool force)
L
Linus Torvalds 已提交
859
{
860
	struct signal_struct *signal = p->signal;
L
Linus Torvalds 已提交
861 862
	struct task_struct *t;

863
	if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
L
Linus Torvalds 已提交
864
		/*
865
		 * The process is in the middle of dying, nothing to do.
L
Linus Torvalds 已提交
866
		 */
867
	} else if (sig_kernel_stop(sig)) {
L
Linus Torvalds 已提交
868 869 870
		/*
		 * This is a stop signal.  Remove SIGCONT from all queues.
		 */
871
		rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
L
Linus Torvalds 已提交
872 873 874
		t = p;
		do {
			rm_from_queue(sigmask(SIGCONT), &t->pending);
875
		} while_each_thread(p, t);
L
Linus Torvalds 已提交
876
	} else if (sig == SIGCONT) {
877
		unsigned int why;
L
Linus Torvalds 已提交
878
		/*
879
		 * Remove all stop signals from all queues, wake all threads.
L
Linus Torvalds 已提交
880
		 */
881
		rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
L
Linus Torvalds 已提交
882 883
		t = p;
		do {
884
			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
L
Linus Torvalds 已提交
885
			rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
886 887 888 889
			if (likely(!(t->ptrace & PT_SEIZED)))
				wake_up_state(t, __TASK_STOPPED);
			else
				ptrace_trap_notify(t);
890
		} while_each_thread(p, t);
L
Linus Torvalds 已提交
891

892 893 894 895 896 897 898 899 900
		/*
		 * 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;
901
		if (signal->flags & SIGNAL_STOP_STOPPED)
902
			why |= SIGNAL_CLD_CONTINUED;
903
		else if (signal->group_stop_count)
904 905 906
			why |= SIGNAL_CLD_STOPPED;

		if (why) {
907
			/*
908
			 * The first thread which returns from do_signal_stop()
909 910 911
			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
			 * notify its parent. See get_signal_to_deliver().
			 */
912 913 914
			signal->flags = why | SIGNAL_STOP_CONTINUED;
			signal->group_stop_count = 0;
			signal->group_exit_code = 0;
L
Linus Torvalds 已提交
915 916
		}
	}
917

918
	return !sig_ignored(p, sig, force);
L
Linus Torvalds 已提交
919 920
}

921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941
/*
 * 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);
}

942
static void complete_signal(int sig, struct task_struct *p, int group)
943 944 945 946 947 948 949 950 951 952 953 954
{
	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;
955
	else if (!group || thread_group_empty(p))
956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982
		/*
		 * 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.
	 */
983 984
	if (sig_fatal(p, sig) &&
	    !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
985
	    !sigismember(&t->real_blocked, sig) &&
T
Tejun Heo 已提交
986
	    (sig == SIGKILL || !t->ptrace)) {
987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001
		/*
		 * 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 {
1002
				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
				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;
}

1018 1019 1020 1021 1022
static inline int legacy_queue(struct sigpending *signals, int sig)
{
	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
}

1023 1024 1025 1026 1027 1028 1029 1030 1031
#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;

1032 1033 1034 1035
	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();
1036 1037 1038 1039 1040 1041 1042 1043
}
#else
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
{
	return;
}
#endif

1044 1045
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
1046
{
1047
	struct sigpending *pending;
1048
	struct sigqueue *q;
1049
	int override_rlimit;
1050
	int ret = 0, result;
1051

1052
	assert_spin_locked(&t->sighand->siglock);
1053

1054
	result = TRACE_SIGNAL_IGNORED;
1055 1056
	if (!prepare_signal(sig, t,
			from_ancestor_ns || (info == SEND_SIG_FORCED)))
1057
		goto ret;
1058 1059

	pending = group ? &t->signal->shared_pending : &t->pending;
1060 1061 1062 1063 1064
	/*
	 * 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.
	 */
1065
	result = TRACE_SIGNAL_ALREADY_PENDING;
1066
	if (legacy_queue(pending, sig))
1067 1068 1069
		goto ret;

	result = TRACE_SIGNAL_DELIVERED;
L
Linus Torvalds 已提交
1070 1071 1072 1073
	/*
	 * fast-pathed signals for kernel-internal things like SIGSTOP
	 * or SIGKILL.
	 */
1074
	if (info == SEND_SIG_FORCED)
L
Linus Torvalds 已提交
1075 1076
		goto out_set;

1077 1078 1079 1080 1081 1082 1083 1084 1085
	/*
	 * 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.
	 */
1086 1087 1088 1089 1090
	if (sig < SIGRTMIN)
		override_rlimit = (is_si_special(info) || info->si_code >= 0);
	else
		override_rlimit = 0;

1091
	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1092
		override_rlimit);
L
Linus Torvalds 已提交
1093
	if (q) {
1094
		list_add_tail(&q->list, &pending->list);
L
Linus Torvalds 已提交
1095
		switch ((unsigned long) info) {
1096
		case (unsigned long) SEND_SIG_NOINFO:
L
Linus Torvalds 已提交
1097 1098 1099
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_USER;
1100
			q->info.si_pid = task_tgid_nr_ns(current,
1101
							task_active_pid_ns(t));
1102
			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1103
			break;
1104
		case (unsigned long) SEND_SIG_PRIV:
L
Linus Torvalds 已提交
1105 1106 1107 1108 1109 1110 1111 1112
			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);
1113 1114
			if (from_ancestor_ns)
				q->info.si_pid = 0;
L
Linus Torvalds 已提交
1115 1116
			break;
		}
1117 1118 1119

		userns_fixup_signal_uid(&q->info, t);

1120
	} else if (!is_si_special(info)) {
1121 1122 1123 1124 1125 1126
		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().
			 */
1127 1128 1129
			result = TRACE_SIGNAL_OVERFLOW_FAIL;
			ret = -EAGAIN;
			goto ret;
1130 1131 1132 1133 1134
		} else {
			/*
			 * This is a silent loss of information.  We still
			 * send the signal, but the *info bits are lost.
			 */
1135
			result = TRACE_SIGNAL_LOSE_INFO;
1136
		}
L
Linus Torvalds 已提交
1137 1138 1139
	}

out_set:
1140
	signalfd_notify(t, sig);
1141
	sigaddset(&pending->signal, sig);
1142
	complete_signal(sig, t, group);
1143 1144 1145
ret:
	trace_signal_generate(sig, info, t, group, result);
	return ret;
L
Linus Torvalds 已提交
1146 1147
}

1148 1149 1150
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
			int group)
{
1151 1152 1153
	int from_ancestor_ns = 0;

#ifdef CONFIG_PID_NS
1154 1155
	from_ancestor_ns = si_fromuser(info) &&
			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1156 1157 1158
#endif

	return __send_signal(sig, info, t, group, from_ancestor_ns);
1159 1160
}

I
Ingo Molnar 已提交
1161 1162 1163
static void print_fatal_signal(struct pt_regs *regs, int signr)
{
	printk("%s/%d: potentially unexpected fatal signal %d.\n",
1164
		current->comm, task_pid_nr(current), signr);
I
Ingo Molnar 已提交
1165

A
Al Viro 已提交
1166
#if defined(__i386__) && !defined(__arch_um__)
1167
	printk("code at %08lx: ", regs->ip);
I
Ingo Molnar 已提交
1168 1169 1170 1171 1172
	{
		int i;
		for (i = 0; i < 16; i++) {
			unsigned char insn;

1173 1174
			if (get_user(insn, (unsigned char *)(regs->ip + i)))
				break;
I
Ingo Molnar 已提交
1175 1176 1177 1178 1179
			printk("%02x ", insn);
		}
	}
#endif
	printk("\n");
1180
	preempt_disable();
I
Ingo Molnar 已提交
1181
	show_regs(regs);
1182
	preempt_enable();
I
Ingo Molnar 已提交
1183 1184 1185 1186 1187 1188 1189 1190 1191 1192
}

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
1193

1194 1195 1196 1197 1198 1199
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
1200 1201 1202
static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
1203
	return send_signal(sig, info, t, 0);
L
Linus Torvalds 已提交
1204 1205
}

1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219
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
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1220 1221 1222
/*
 * Force a signal that the process can't ignore: if necessary
 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1223 1224 1225 1226 1227
 *
 * 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.
 *
1228 1229
 * We don't want to have recursive SIGSEGV's etc, for example,
 * that is why we also clear SIGNAL_UNKILLABLE.
L
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1230 1231 1232 1233 1234
 */
int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
	unsigned long int flags;
1235 1236
	int ret, blocked, ignored;
	struct k_sigaction *action;
L
Linus Torvalds 已提交
1237 1238

	spin_lock_irqsave(&t->sighand->siglock, flags);
1239 1240 1241 1242 1243 1244 1245
	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
1246
			recalc_sigpending_and_wake(t);
1247
		}
L
Linus Torvalds 已提交
1248
	}
1249 1250
	if (action->sa.sa_handler == SIG_DFL)
		t->signal->flags &= ~SIGNAL_UNKILLABLE;
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1251 1252 1253 1254 1255 1256 1257 1258 1259
	ret = specific_send_sig_info(sig, info, t);
	spin_unlock_irqrestore(&t->sighand->siglock, flags);

	return ret;
}

/*
 * Nuke all other threads in the group.
 */
1260
int zap_other_threads(struct task_struct *p)
L
Linus Torvalds 已提交
1261
{
1262 1263
	struct task_struct *t = p;
	int count = 0;
L
Linus Torvalds 已提交
1264 1265 1266

	p->signal->group_stop_count = 0;

1267
	while_each_thread(p, t) {
1268
		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1269 1270 1271
		count++;

		/* Don't bother with already dead threads */
L
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1272 1273 1274 1275 1276
		if (t->exit_state)
			continue;
		sigaddset(&t->pending.signal, SIGKILL);
		signal_wake_up(t, 1);
	}
1277 1278

	return count;
L
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1279 1280
}

1281 1282
struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
					   unsigned long *flags)
1283 1284 1285 1286
{
	struct sighand_struct *sighand;

	for (;;) {
1287 1288
		local_irq_save(*flags);
		rcu_read_lock();
1289
		sighand = rcu_dereference(tsk->sighand);
1290 1291 1292
		if (unlikely(sighand == NULL)) {
			rcu_read_unlock();
			local_irq_restore(*flags);
1293
			break;
1294
		}
1295

1296 1297 1298
		spin_lock(&sighand->siglock);
		if (likely(sighand == tsk->sighand)) {
			rcu_read_unlock();
1299
			break;
1300 1301 1302 1303
		}
		spin_unlock(&sighand->siglock);
		rcu_read_unlock();
		local_irq_restore(*flags);
1304 1305 1306 1307 1308
	}

	return sighand;
}

1309 1310 1311
/*
 * send signal info to all the members of a group
 */
L
Linus Torvalds 已提交
1312 1313
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
1314 1315 1316 1317 1318
	int ret;

	rcu_read_lock();
	ret = check_kill_permission(sig, info, p);
	rcu_read_unlock();
1319

1320 1321
	if (!ret && sig)
		ret = do_send_sig_info(sig, info, p, true);
L
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1322 1323 1324 1325 1326

	return ret;
}

/*
1327
 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
L
Linus Torvalds 已提交
1328
 * control characters do (^C, ^Z etc)
1329
 * - the caller must hold at least a readlock on tasklist_lock
L
Linus Torvalds 已提交
1330
 */
1331
int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
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1332 1333 1334 1335 1336 1337
{
	struct task_struct *p = NULL;
	int retval, success;

	success = 0;
	retval = -ESRCH;
1338
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
L
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1339 1340 1341
		int err = group_send_sig_info(sig, info, p);
		success |= !err;
		retval = err;
1342
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
L
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1343 1344 1345
	return success ? 0 : retval;
}

1346
int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
L
Linus Torvalds 已提交
1347
{
1348
	int error = -ESRCH;
L
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1349 1350
	struct task_struct *p;

I
Ingo Molnar 已提交
1351
	rcu_read_lock();
1352
retry:
1353
	p = pid_task(pid, PIDTYPE_PID);
1354
	if (p) {
L
Linus Torvalds 已提交
1355
		error = group_send_sig_info(sig, info, p);
1356 1357 1358 1359 1360 1361 1362 1363 1364
		if (unlikely(error == -ESRCH))
			/*
			 * 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.
			 */
			goto retry;
	}
I
Ingo Molnar 已提交
1365
	rcu_read_unlock();
1366

L
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1367 1368 1369
	return error;
}

1370
int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1371 1372 1373
{
	int error;
	rcu_read_lock();
1374
	error = kill_pid_info(sig, info, find_vpid(pid));
1375 1376 1377 1378
	rcu_read_unlock();
	return error;
}

1379 1380 1381 1382
static int kill_as_cred_perm(const struct cred *cred,
			     struct task_struct *target)
{
	const struct cred *pcred = __task_cred(target);
1383 1384
	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))
1385 1386 1387 1388
		return 0;
	return 1;
}

1389
/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1390 1391
int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
			 const struct cred *cred, u32 secid)
1392 1393 1394
{
	int ret = -EINVAL;
	struct task_struct *p;
1395
	unsigned long flags;
1396 1397 1398 1399

	if (!valid_signal(sig))
		return ret;

1400
	rcu_read_lock();
1401
	p = pid_task(pid, PIDTYPE_PID);
1402 1403 1404 1405
	if (!p) {
		ret = -ESRCH;
		goto out_unlock;
	}
1406
	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1407 1408 1409
		ret = -EPERM;
		goto out_unlock;
	}
1410 1411 1412
	ret = security_task_kill(p, info, sig, secid);
	if (ret)
		goto out_unlock;
1413 1414 1415 1416 1417 1418 1419

	if (sig) {
		if (lock_task_sighand(p, &flags)) {
			ret = __send_signal(sig, info, p, 1, 0);
			unlock_task_sighand(p, &flags);
		} else
			ret = -ESRCH;
1420 1421
	}
out_unlock:
1422
	rcu_read_unlock();
1423 1424
	return ret;
}
1425
EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
L
Linus Torvalds 已提交
1426 1427 1428 1429 1430 1431 1432 1433

/*
 * 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.
 */

1434
static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
L
Linus Torvalds 已提交
1435
{
1436
	int ret;
1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449

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

	read_lock(&tasklist_lock);
	if (pid != -1) {
		ret = __kill_pgrp_info(sig, info,
				pid ? find_vpid(-pid) : task_pgrp(current));
	} else {
L
Linus Torvalds 已提交
1450 1451 1452 1453
		int retval = 0, count = 0;
		struct task_struct * p;

		for_each_process(p) {
1454 1455
			if (task_pid_vnr(p) > 1 &&
					!same_thread_group(p, current)) {
L
Linus Torvalds 已提交
1456 1457 1458 1459 1460 1461
				int err = group_send_sig_info(sig, info, p);
				++count;
				if (err != -EPERM)
					retval = err;
			}
		}
1462
		ret = count ? retval : -ESRCH;
L
Linus Torvalds 已提交
1463
	}
1464 1465
	read_unlock(&tasklist_lock);

1466
	return ret;
L
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1467 1468 1469 1470 1471 1472
}

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

1473
int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
L
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1474 1475 1476 1477 1478
{
	/*
	 * Make sure legacy kernel users don't send in bad values
	 * (normal paths check this in check_kill_permission).
	 */
1479
	if (!valid_signal(sig))
L
Linus Torvalds 已提交
1480 1481
		return -EINVAL;

1482
	return do_send_sig_info(sig, info, p, false);
L
Linus Torvalds 已提交
1483 1484
}

1485 1486 1487
#define __si_special(priv) \
	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)

L
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1488 1489 1490
int
send_sig(int sig, struct task_struct *p, int priv)
{
1491
	return send_sig_info(sig, __si_special(priv), p);
L
Linus Torvalds 已提交
1492 1493 1494 1495 1496
}

void
force_sig(int sig, struct task_struct *p)
{
1497
	force_sig_info(sig, SEND_SIG_PRIV, p);
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1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518
}

/*
 * 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;
}

1519 1520
int kill_pgrp(struct pid *pid, int sig, int priv)
{
1521 1522 1523 1524 1525 1526 1527
	int ret;

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

	return ret;
1528 1529 1530 1531 1532 1533 1534 1535 1536
}
EXPORT_SYMBOL(kill_pgrp);

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

L
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1537 1538 1539 1540
/*
 * 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
1541
 * expirations or I/O completions".  In the case of POSIX Timers
L
Linus Torvalds 已提交
1542 1543 1544 1545 1546 1547
 * 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)
{
1548
	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
L
Linus Torvalds 已提交
1549

1550
	if (q)
L
Linus Torvalds 已提交
1551
		q->flags |= SIGQUEUE_PREALLOC;
1552 1553

	return q;
L
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1554 1555 1556 1557 1558
}

void sigqueue_free(struct sigqueue *q)
{
	unsigned long flags;
1559 1560
	spinlock_t *lock = &current->sighand->siglock;

L
Linus Torvalds 已提交
1561 1562
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
	/*
1563 1564
	 * We must hold ->siglock while testing q->list
	 * to serialize with collect_signal() or with
1565
	 * __exit_signal()->flush_sigqueue().
L
Linus Torvalds 已提交
1566
	 */
1567
	spin_lock_irqsave(lock, flags);
1568 1569 1570 1571 1572
	q->flags &= ~SIGQUEUE_PREALLOC;
	/*
	 * If it is queued it will be freed when dequeued,
	 * like the "regular" sigqueue.
	 */
1573
	if (!list_empty(&q->list))
1574
		q = NULL;
1575 1576
	spin_unlock_irqrestore(lock, flags);

1577 1578
	if (q)
		__sigqueue_free(q);
L
Linus Torvalds 已提交
1579 1580
}

1581
int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1582
{
1583
	int sig = q->info.si_signo;
1584
	struct sigpending *pending;
1585
	unsigned long flags;
1586
	int ret, result;
1587

1588
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1589 1590 1591 1592 1593

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

1594
	ret = 1; /* the signal is ignored */
1595
	result = TRACE_SIGNAL_IGNORED;
1596
	if (!prepare_signal(sig, t, false))
1597 1598 1599
		goto out;

	ret = 0;
1600 1601 1602 1603 1604 1605 1606
	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++;
1607
		result = TRACE_SIGNAL_ALREADY_PENDING;
1608
		goto out;
1609
	}
1610
	q->info.si_overrun = 0;
1611 1612

	signalfd_notify(t, sig);
1613
	pending = group ? &t->signal->shared_pending : &t->pending;
1614 1615
	list_add_tail(&q->list, &pending->list);
	sigaddset(&pending->signal, sig);
1616
	complete_signal(sig, t, group);
1617
	result = TRACE_SIGNAL_DELIVERED;
1618
out:
1619
	trace_signal_generate(sig, &q->info, t, group, result);
1620 1621 1622
	unlock_task_sighand(t, &flags);
ret:
	return ret;
1623 1624
}

L
Linus Torvalds 已提交
1625 1626 1627
/*
 * 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
1628
 *
1629 1630
 * Returns true if our parent ignored us and so we've switched to
 * self-reaping.
L
Linus Torvalds 已提交
1631
 */
1632
bool do_notify_parent(struct task_struct *tsk, int sig)
L
Linus Torvalds 已提交
1633 1634 1635 1636
{
	struct siginfo info;
	unsigned long flags;
	struct sighand_struct *psig;
1637
	bool autoreap = false;
L
Linus Torvalds 已提交
1638 1639 1640 1641

	BUG_ON(sig == -1);

 	/* do_notify_parent_cldstop should have been called instead.  */
M
Matthew Wilcox 已提交
1642
 	BUG_ON(task_is_stopped_or_traced(tsk));
L
Linus Torvalds 已提交
1643

T
Tejun Heo 已提交
1644
	BUG_ON(!tsk->ptrace &&
L
Linus Torvalds 已提交
1645 1646
	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));

1647 1648 1649 1650 1651 1652 1653 1654 1655
	if (sig != SIGCHLD) {
		/*
		 * This is only possible if parent == real_parent.
		 * Check if it has changed security domain.
		 */
		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
			sig = SIGCHLD;
	}

L
Linus Torvalds 已提交
1656 1657
	info.si_signo = sig;
	info.si_errno = 0;
1658
	/*
1659 1660
	 * We are under tasklist_lock here so our parent is tied to
	 * us and cannot change.
1661
	 *
1662 1663
	 * task_active_pid_ns will always return the same pid namespace
	 * until a task passes through release_task.
1664 1665 1666 1667 1668 1669
	 *
	 * 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();
1670
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1671 1672
	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
				       task_uid(tsk));
1673 1674
	rcu_read_unlock();

1675 1676
	info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
	info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
L
Linus Torvalds 已提交
1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689

	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
1690
	if (!tsk->ptrace && sig == SIGCHLD &&
L
Linus Torvalds 已提交
1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707
	    (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).
		 */
1708
		autoreap = true;
L
Linus Torvalds 已提交
1709
		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1710
			sig = 0;
L
Linus Torvalds 已提交
1711
	}
1712
	if (valid_signal(sig) && sig)
L
Linus Torvalds 已提交
1713 1714 1715
		__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
1716

1717
	return autoreap;
L
Linus Torvalds 已提交
1718 1719
}

1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734
/**
 * 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
1735 1736 1737
{
	struct siginfo info;
	unsigned long flags;
1738
	struct task_struct *parent;
L
Linus Torvalds 已提交
1739 1740
	struct sighand_struct *sighand;

1741
	if (for_ptracer) {
1742
		parent = tsk->parent;
1743
	} else {
1744 1745 1746 1747
		tsk = tsk->group_leader;
		parent = tsk->real_parent;
	}

L
Linus Torvalds 已提交
1748 1749
	info.si_signo = SIGCHLD;
	info.si_errno = 0;
1750
	/*
1751
	 * see comment in do_notify_parent() about the following 4 lines
1752 1753
	 */
	rcu_read_lock();
1754
	info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
1755
	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1756 1757
	rcu_read_unlock();

1758 1759
	info.si_utime = cputime_to_clock_t(tsk->utime);
	info.si_stime = cputime_to_clock_t(tsk->stime);
L
Linus Torvalds 已提交
1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787

 	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);
}

1788 1789
static inline int may_ptrace_stop(void)
{
T
Tejun Heo 已提交
1790
	if (!likely(current->ptrace))
1791 1792 1793 1794 1795 1796 1797
		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
1798
	 * ->siglock we must see ->core_state != NULL. Otherwise it
1799 1800
	 * is safe to enter schedule().
	 */
1801
	if (unlikely(current->mm->core_state) &&
1802 1803 1804 1805 1806 1807
	    unlikely(current->mm == current->parent->mm))
		return 0;

	return 1;
}

R
Roland McGrath 已提交
1808
/*
1809
 * Return non-zero if there is a SIGKILL that should be waking us up.
R
Roland McGrath 已提交
1810 1811 1812 1813
 * Called with the siglock held.
 */
static int sigkill_pending(struct task_struct *tsk)
{
1814 1815
	return	sigismember(&tsk->pending.signal, SIGKILL) ||
		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
R
Roland McGrath 已提交
1816 1817
}

L
Linus Torvalds 已提交
1818 1819 1820 1821 1822 1823 1824 1825
/*
 * 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.
 *
1826 1827
 * 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
1828
 */
T
Tejun Heo 已提交
1829
static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1830 1831
	__releases(&current->sighand->siglock)
	__acquires(&current->sighand->siglock)
L
Linus Torvalds 已提交
1832
{
1833 1834
	bool gstop_done = false;

R
Roland McGrath 已提交
1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849
	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);
1850 1851
		if (sigkill_pending(current))
			return;
R
Roland McGrath 已提交
1852 1853
	}

L
Linus Torvalds 已提交
1854
	/*
1855 1856 1857 1858 1859
	 * 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
1860
	 */
1861
	set_current_state(TASK_TRACED);
L
Linus Torvalds 已提交
1862 1863 1864 1865

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

1866
	/*
1867 1868
	 * If @why is CLD_STOPPED, we're trapping to participate in a group
	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1869 1870 1871
	 * 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.
1872
	 */
1873
	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1874
		gstop_done = task_participate_group_stop(current);
1875

1876
	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1877
	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1878 1879
	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1880

1881
	/* entering a trap, clear TRAPPING */
1882
	task_clear_jobctl_trapping(current);
1883

L
Linus Torvalds 已提交
1884 1885
	spin_unlock_irq(&current->sighand->siglock);
	read_lock(&tasklist_lock);
1886
	if (may_ptrace_stop()) {
1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897
		/*
		 * 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);
1898
		if (gstop_done && ptrace_reparented(current))
1899 1900
			do_notify_parent_cldstop(current, false, why);

M
Miklos Szeredi 已提交
1901 1902 1903 1904 1905 1906 1907
		/*
		 * 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
1908
		read_unlock(&tasklist_lock);
M
Miklos Szeredi 已提交
1909
		preempt_enable_no_resched();
L
Linus Torvalds 已提交
1910 1911 1912 1913
		schedule();
	} else {
		/*
		 * By the time we got the lock, our tracer went away.
1914
		 * Don't drop the lock yet, another tracer may come.
1915 1916 1917
		 *
		 * If @gstop_done, the ptracer went away between group stop
		 * completion and here.  During detach, it would have set
1918 1919 1920
		 * 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
1921
		 */
1922 1923 1924
		if (gstop_done)
			do_notify_parent_cldstop(current, false, why);

1925
		__set_current_state(TASK_RUNNING);
1926 1927
		if (clear_code)
			current->exit_code = 0;
1928
		read_unlock(&tasklist_lock);
L
Linus Torvalds 已提交
1929 1930
	}

R
Roland McGrath 已提交
1931 1932 1933 1934 1935 1936 1937
	/*
	 * While in TASK_TRACED, we were considered "frozen enough".
	 * Now that we woke up, it's crucial if we're supposed to be
	 * frozen that we freeze now before running anything substantial.
	 */
	try_to_freeze();

L
Linus Torvalds 已提交
1938 1939 1940 1941 1942 1943 1944 1945
	/*
	 * 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
1946 1947 1948
	/* LISTENING can be set only during STOP traps, clear it */
	current->jobctl &= ~JOBCTL_LISTENING;

L
Linus Torvalds 已提交
1949 1950 1951
	/*
	 * Queued signals ignored us while we were stopped for tracing.
	 * So check for any that we should take before resuming user mode.
1952
	 * This sets TIF_SIGPENDING, but never clears it.
L
Linus Torvalds 已提交
1953
	 */
1954
	recalc_sigpending_tsk(current);
L
Linus Torvalds 已提交
1955 1956
}

T
Tejun Heo 已提交
1957
static void ptrace_do_notify(int signr, int exit_code, int why)
L
Linus Torvalds 已提交
1958 1959 1960 1961
{
	siginfo_t info;

	memset(&info, 0, sizeof info);
T
Tejun Heo 已提交
1962
	info.si_signo = signr;
L
Linus Torvalds 已提交
1963
	info.si_code = exit_code;
1964
	info.si_pid = task_pid_vnr(current);
1965
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1966 1967

	/* Let the debugger run.  */
T
Tejun Heo 已提交
1968 1969 1970 1971 1972 1973
	ptrace_stop(exit_code, why, 1, &info);
}

void ptrace_notify(int exit_code)
{
	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1974 1975 1976 1977 1978 1979 1980
	if (unlikely(current->task_works)) {
		if (test_and_clear_ti_thread_flag(current_thread_info(),
						   TIF_NOTIFY_RESUME)) {
			smp_mb__after_clear_bit();
			task_work_run();
		}
	}
T
Tejun Heo 已提交
1981

L
Linus Torvalds 已提交
1982
	spin_lock_irq(&current->sighand->siglock);
T
Tejun Heo 已提交
1983
	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
L
Linus Torvalds 已提交
1984 1985 1986
	spin_unlock_irq(&current->sighand->siglock);
}

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
/**
 * 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
2008
 */
2009 2010
static bool do_signal_stop(int signr)
	__releases(&current->sighand->siglock)
L
Linus Torvalds 已提交
2011 2012 2013
{
	struct signal_struct *sig = current->signal;

2014 2015
	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
		unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
2016 2017
		struct task_struct *t;

2018 2019
		/* signr will be recorded in task->jobctl for retries */
		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
2020

2021
		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
2022
		    unlikely(signal_group_exit(sig)))
2023
			return false;
L
Linus Torvalds 已提交
2024
		/*
2025 2026 2027 2028 2029 2030 2031
		 * 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
2032 2033
		 * cause two group stops when !ptraced.  That is why we
		 * also check !task_is_stopped(t) below.
2034 2035 2036 2037 2038 2039 2040 2041
		 *
		 * 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
2042
		 */
2043 2044
		if (!(sig->flags & SIGNAL_STOP_STOPPED))
			sig->group_exit_code = signr;
L
Linus Torvalds 已提交
2045

2046 2047 2048 2049
		sig->group_stop_count = 0;

		if (task_set_jobctl_pending(current, signr | gstop))
			sig->group_stop_count++;
L
Linus Torvalds 已提交
2050

2051 2052
		for (t = next_thread(current); t != current;
		     t = next_thread(t)) {
L
Linus Torvalds 已提交
2053
			/*
2054 2055 2056
			 * 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
2057
			 */
2058 2059
			if (!task_is_stopped(t) &&
			    task_set_jobctl_pending(t, signr | gstop)) {
2060
				sig->group_stop_count++;
2061 2062 2063 2064
				if (likely(!(t->ptrace & PT_SEIZED)))
					signal_wake_up(t, 0);
				else
					ptrace_trap_notify(t);
2065
			}
2066
		}
L
Linus Torvalds 已提交
2067
	}
2068

T
Tejun Heo 已提交
2069
	if (likely(!current->ptrace)) {
2070
		int notify = 0;
L
Linus Torvalds 已提交
2071

2072 2073 2074 2075 2076 2077 2078 2079
		/*
		 * 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;

2080
		__set_current_state(TASK_STOPPED);
2081 2082
		spin_unlock_irq(&current->sighand->siglock);

2083 2084 2085 2086 2087 2088 2089 2090 2091
		/*
		 * 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.
		 */
2092 2093
		if (notify) {
			read_lock(&tasklist_lock);
2094
			do_notify_parent_cldstop(current, false, notify);
2095 2096 2097 2098 2099
			read_unlock(&tasklist_lock);
		}

		/* Now we don't run again until woken by SIGCONT or SIGKILL */
		schedule();
2100
		return true;
2101
	} else {
2102 2103 2104 2105 2106 2107
		/*
		 * 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;
2108
	}
2109
}
L
Linus Torvalds 已提交
2110

2111 2112 2113
/**
 * do_jobctl_trap - take care of ptrace jobctl traps
 *
T
Tejun Heo 已提交
2114 2115 2116 2117 2118 2119 2120
 * 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.
2121 2122 2123 2124 2125 2126 2127
 *
 * 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
2128
	struct signal_struct *signal = current->signal;
2129
	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2130

T
Tejun Heo 已提交
2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141
	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;
2142
	}
L
Linus Torvalds 已提交
2143 2144
}

R
Roland McGrath 已提交
2145 2146 2147 2148
static int ptrace_signal(int signr, siginfo_t *info,
			 struct pt_regs *regs, void *cookie)
{
	ptrace_signal_deliver(regs, cookie);
2149 2150 2151 2152 2153 2154 2155 2156 2157 2158
	/*
	 * 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
2159
	ptrace_stop(signr, CLD_TRAPPED, 0, info);
R
Roland McGrath 已提交
2160 2161 2162 2163 2164 2165 2166 2167

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

	current->exit_code = 0;

2168 2169 2170 2171 2172 2173
	/*
	 * 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
2174 2175 2176 2177
	if (signr != info->si_signo) {
		info->si_signo = signr;
		info->si_errno = 0;
		info->si_code = SI_USER;
2178
		rcu_read_lock();
R
Roland McGrath 已提交
2179
		info->si_pid = task_pid_vnr(current->parent);
2180 2181
		info->si_uid = from_kuid_munged(current_user_ns(),
						task_uid(current->parent));
2182
		rcu_read_unlock();
R
Roland McGrath 已提交
2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193
	}

	/* 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;
}

L
Linus Torvalds 已提交
2194 2195 2196
int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
			  struct pt_regs *regs, void *cookie)
{
2197 2198 2199
	struct sighand_struct *sighand = current->sighand;
	struct signal_struct *signal = current->signal;
	int signr;
L
Linus Torvalds 已提交
2200

2201 2202 2203 2204 2205 2206 2207 2208
	if (unlikely(current->task_works)) {
		if (test_and_clear_ti_thread_flag(current_thread_info(),
						   TIF_NOTIFY_RESUME)) {
			smp_mb__after_clear_bit();
			task_work_run();
		}
	}

2209 2210 2211
	if (unlikely(uprobe_deny_signal()))
		return 0;

R
Roland McGrath 已提交
2212 2213 2214 2215 2216 2217 2218
relock:
	/*
	 * We'll jump back here after any time we were stopped in TASK_STOPPED.
	 * While in TASK_STOPPED, we were considered "frozen enough".
	 * Now that we woke up, it's crucial if we're supposed to be
	 * frozen that we freeze now before running anything substantial.
	 */
2219 2220
	try_to_freeze();

2221
	spin_lock_irq(&sighand->siglock);
2222 2223 2224 2225 2226
	/*
	 * 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.
	 */
2227
	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2228 2229 2230 2231 2232 2233 2234
		int why;

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

2235
		signal->flags &= ~SIGNAL_CLD_MASK;
2236

2237
		spin_unlock_irq(&sighand->siglock);
R
Roland McGrath 已提交
2238

2239 2240 2241 2242 2243 2244 2245 2246
		/*
		 * 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
2247
		read_lock(&tasklist_lock);
2248 2249
		do_notify_parent_cldstop(current, false, why);

2250 2251 2252
		if (ptrace_reparented(current->group_leader))
			do_notify_parent_cldstop(current->group_leader,
						true, why);
T
Tejun Heo 已提交
2253
		read_unlock(&tasklist_lock);
2254

2255 2256 2257
		goto relock;
	}

L
Linus Torvalds 已提交
2258 2259
	for (;;) {
		struct k_sigaction *ka;
2260

T
Tejun Heo 已提交
2261 2262
		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
		    do_signal_stop(0))
2263
			goto relock;
2264

2265 2266 2267 2268 2269
		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
			do_jobctl_trap();
			spin_unlock_irq(&sighand->siglock);
			goto relock;
		}
L
Linus Torvalds 已提交
2270

T
Tejun Heo 已提交
2271
		signr = dequeue_signal(current, &current->blocked, info);
2272

T
Tejun Heo 已提交
2273 2274
		if (!signr)
			break; /* will return 0 */
2275

2276
		if (unlikely(current->ptrace) && signr != SIGKILL) {
T
Tejun Heo 已提交
2277 2278 2279 2280
			signr = ptrace_signal(signr, info,
					      regs, cookie);
			if (!signr)
				continue;
L
Linus Torvalds 已提交
2281 2282
		}

T
Tejun Heo 已提交
2283 2284
		ka = &sighand->action[signr-1];

2285 2286 2287
		/* Trace actually delivered signals. */
		trace_signal_deliver(signr, info, ka);

L
Linus Torvalds 已提交
2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305
		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
			continue;
		if (ka->sa.sa_handler != SIG_DFL) {
			/* Run the handler.  */
			*return_ka = *ka;

			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;

2306
		/*
2307
		 * Global init gets no signals it doesn't want.
2308 2309 2310 2311 2312 2313 2314
		 * 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.
2315
		 */
2316
		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2317
				!sig_kernel_only(signr))
L
Linus Torvalds 已提交
2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331
			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) {
2332
				spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2333 2334 2335

				/* signals can be posted during this window */

2336
				if (is_current_pgrp_orphaned())
L
Linus Torvalds 已提交
2337 2338
					goto relock;

2339
				spin_lock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2340 2341
			}

2342
			if (likely(do_signal_stop(info->si_signo))) {
L
Linus Torvalds 已提交
2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353
				/* It released the siglock.  */
				goto relock;
			}

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

2354
		spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2355 2356 2357 2358 2359

		/*
		 * Anything else is fatal, maybe with a core dump.
		 */
		current->flags |= PF_SIGNALED;
2360

L
Linus Torvalds 已提交
2361
		if (sig_kernel_coredump(signr)) {
2362
			if (print_fatal_signals)
2363
				print_fatal_signal(regs, info->si_signo);
L
Linus Torvalds 已提交
2364 2365 2366 2367 2368 2369 2370 2371
			/*
			 * 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.
			 */
2372
			do_coredump(info->si_signo, info->si_signo, regs);
L
Linus Torvalds 已提交
2373 2374 2375 2376 2377
		}

		/*
		 * Death signals, no core dump.
		 */
2378
		do_group_exit(info->si_signo);
L
Linus Torvalds 已提交
2379 2380
		/* NOTREACHED */
	}
2381
	spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2382 2383 2384
	return signr;
}

2385
/**
A
Al Viro 已提交
2386 2387 2388 2389 2390 2391
 * signal_delivered - 
 * @sig:		number of signal being delivered
 * @info:		siginfo_t of signal being delivered
 * @ka:			sigaction setting that chose the handler
 * @regs:		user register state
 * @stepping:		nonzero if debugger single-step or block-step in use
2392 2393
 *
 * This function should be called when a signal has succesfully been
A
Al Viro 已提交
2394 2395 2396
 * delivered. It updates the blocked signals accordingly (@ka->sa.sa_mask
 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
 * is set in @ka->sa.sa_flags.  Tracing is notified.
2397
 */
A
Al Viro 已提交
2398 2399
void signal_delivered(int sig, siginfo_t *info, struct k_sigaction *ka,
			struct pt_regs *regs, int stepping)
2400 2401 2402
{
	sigset_t blocked;

2403 2404 2405 2406 2407 2408
	/* 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();

2409 2410
	sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
	if (!(ka->sa.sa_flags & SA_NODEFER))
A
Al Viro 已提交
2411
		sigaddset(&blocked, sig);
2412
	set_current_blocked(&blocked);
A
Al Viro 已提交
2413
	tracehook_signal_handler(sig, info, ka, regs, stepping);
2414 2415
}

2416 2417
/*
 * It could be that complete_signal() picked us to notify about the
2418 2419
 * group-wide signal. Other threads should be notified now to take
 * the shared signals in @which since we will not.
2420
 */
2421
static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2422
{
2423
	sigset_t retarget;
2424 2425
	struct task_struct *t;

2426 2427 2428 2429
	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
	if (sigisemptyset(&retarget))
		return;

2430 2431
	t = tsk;
	while_each_thread(tsk, t) {
2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444
		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;
2445 2446 2447
	}
}

O
Oleg Nesterov 已提交
2448 2449 2450
void exit_signals(struct task_struct *tsk)
{
	int group_stop = 0;
2451
	sigset_t unblocked;
O
Oleg Nesterov 已提交
2452

2453 2454 2455 2456 2457 2458
	/*
	 * @tsk is about to have PF_EXITING set - lock out users which
	 * expect stable threadgroup.
	 */
	threadgroup_change_begin(tsk);

2459 2460
	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
		tsk->flags |= PF_EXITING;
2461
		threadgroup_change_end(tsk);
2462
		return;
O
Oleg Nesterov 已提交
2463 2464
	}

2465
	spin_lock_irq(&tsk->sighand->siglock);
O
Oleg Nesterov 已提交
2466 2467 2468 2469 2470
	/*
	 * From now this task is not visible for group-wide signals,
	 * see wants_signal(), do_signal_stop().
	 */
	tsk->flags |= PF_EXITING;
2471 2472 2473

	threadgroup_change_end(tsk);

2474 2475 2476
	if (!signal_pending(tsk))
		goto out;

2477 2478 2479
	unblocked = tsk->blocked;
	signotset(&unblocked);
	retarget_shared_pending(tsk, &unblocked);
2480

2481
	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2482
	    task_participate_group_stop(tsk))
T
Tejun Heo 已提交
2483
		group_stop = CLD_STOPPED;
2484
out:
O
Oleg Nesterov 已提交
2485 2486
	spin_unlock_irq(&tsk->sighand->siglock);

2487 2488 2489 2490
	/*
	 * If group stop has completed, deliver the notification.  This
	 * should always go to the real parent of the group leader.
	 */
2491
	if (unlikely(group_stop)) {
O
Oleg Nesterov 已提交
2492
		read_lock(&tasklist_lock);
2493
		do_notify_parent_cldstop(tsk, false, group_stop);
O
Oleg Nesterov 已提交
2494 2495 2496 2497
		read_unlock(&tasklist_lock);
	}
}

L
Linus Torvalds 已提交
2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512
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);
EXPORT_SYMBOL(block_all_signals);
EXPORT_SYMBOL(unblock_all_signals);


/*
 * System call entry points.
 */

2513 2514 2515
/**
 *  sys_restart_syscall - restart a system call
 */
2516
SYSCALL_DEFINE0(restart_syscall)
L
Linus Torvalds 已提交
2517 2518 2519 2520 2521 2522 2523 2524 2525 2526
{
	struct restart_block *restart = &current_thread_info()->restart_block;
	return restart->fn(restart);
}

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

2527 2528 2529 2530 2531
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. */
2532
		sigandnsets(&newblocked, newset, &current->blocked);
2533 2534 2535 2536 2537 2538
		retarget_shared_pending(tsk, &newblocked);
	}
	tsk->blocked = *newset;
	recalc_sigpending();
}

2539 2540 2541 2542 2543 2544
/**
 * 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
2545
 */
2546 2547 2548 2549 2550 2551 2552 2553 2554 2555
void set_current_blocked(sigset_t *newset)
{
	struct task_struct *tsk = current;
	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
	spin_lock_irq(&tsk->sighand->siglock);
	__set_task_blocked(tsk, newset);
	spin_unlock_irq(&tsk->sighand->siglock);
}

void __set_current_blocked(const sigset_t *newset)
2556 2557 2558 2559
{
	struct task_struct *tsk = current;

	spin_lock_irq(&tsk->sighand->siglock);
2560
	__set_task_blocked(tsk, newset);
2561 2562
	spin_unlock_irq(&tsk->sighand->siglock);
}
L
Linus Torvalds 已提交
2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573

/*
 * 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)
{
2574 2575
	struct task_struct *tsk = current;
	sigset_t newset;
L
Linus Torvalds 已提交
2576

2577
	/* Lockless, only current can change ->blocked, never from irq */
2578
	if (oldset)
2579
		*oldset = tsk->blocked;
2580

L
Linus Torvalds 已提交
2581 2582
	switch (how) {
	case SIG_BLOCK:
2583
		sigorsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2584 2585
		break;
	case SIG_UNBLOCK:
2586
		sigandnsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2587 2588
		break;
	case SIG_SETMASK:
2589
		newset = *set;
L
Linus Torvalds 已提交
2590 2591
		break;
	default:
2592
		return -EINVAL;
L
Linus Torvalds 已提交
2593
	}
2594

2595
	__set_current_blocked(&newset);
2596
	return 0;
L
Linus Torvalds 已提交
2597 2598
}

2599 2600 2601
/**
 *  sys_rt_sigprocmask - change the list of currently blocked signals
 *  @how: whether to add, remove, or set signals
R
Randy Dunlap 已提交
2602
 *  @nset: stores pending signals
2603 2604 2605
 *  @oset: previous value of signal mask if non-null
 *  @sigsetsize: size of sigset_t type
 */
2606
SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2607
		sigset_t __user *, oset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2608 2609
{
	sigset_t old_set, new_set;
2610
	int error;
L
Linus Torvalds 已提交
2611 2612 2613

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
2614
		return -EINVAL;
L
Linus Torvalds 已提交
2615

2616 2617 2618 2619 2620
	old_set = current->blocked;

	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2621 2622
		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

2623
		error = sigprocmask(how, &new_set, NULL);
L
Linus Torvalds 已提交
2624
		if (error)
2625 2626
			return error;
	}
L
Linus Torvalds 已提交
2627

2628 2629 2630
	if (oset) {
		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2631
	}
2632 2633

	return 0;
L
Linus Torvalds 已提交
2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657
}

long do_sigpending(void __user *set, unsigned long sigsetsize)
{
	long error = -EINVAL;
	sigset_t pending;

	if (sigsetsize > sizeof(sigset_t))
		goto out;

	spin_lock_irq(&current->sighand->siglock);
	sigorsets(&pending, &current->pending.signal,
		  &current->signal->shared_pending.signal);
	spin_unlock_irq(&current->sighand->siglock);

	/* Outside the lock because only this thread touches it.  */
	sigandsets(&pending, &current->blocked, &pending);

	error = -EFAULT;
	if (!copy_to_user(set, &pending, sigsetsize))
		error = 0;

out:
	return error;
2658
}
L
Linus Torvalds 已提交
2659

2660 2661 2662 2663 2664 2665
/**
 *  sys_rt_sigpending - examine a pending signal that has been raised
 *			while blocked
 *  @set: stores pending signals
 *  @sigsetsize: size of sigset_t type or larger
 */
2666
SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
L
Linus Torvalds 已提交
2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684
{
	return do_sigpending(set, sigsetsize);
}

#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER

int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
{
	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.
2685 2686
	 * Please remember to update the signalfd_copyinfo() function
	 * inside fs/signalfd.c too, in case siginfo_t changes.
L
Linus Torvalds 已提交
2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711
	 * It should never copy any pad contained in the structure
	 * to avoid security leaks, but must copy the generic
	 * 3 ints plus the relevant union member.
	 */
	err = __put_user(from->si_signo, &to->si_signo);
	err |= __put_user(from->si_errno, &to->si_errno);
	err |= __put_user((short)from->si_code, &to->si_code);
	switch (from->si_code & __SI_MASK) {
	case __SI_KILL:
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		break;
	case __SI_TIMER:
		 err |= __put_user(from->si_tid, &to->si_tid);
		 err |= __put_user(from->si_overrun, &to->si_overrun);
		 err |= __put_user(from->si_ptr, &to->si_ptr);
		break;
	case __SI_POLL:
		err |= __put_user(from->si_band, &to->si_band);
		err |= __put_user(from->si_fd, &to->si_fd);
		break;
	case __SI_FAULT:
		err |= __put_user(from->si_addr, &to->si_addr);
#ifdef __ARCH_SI_TRAPNO
		err |= __put_user(from->si_trapno, &to->si_trapno);
A
Andi Kleen 已提交
2712 2713
#endif
#ifdef BUS_MCEERR_AO
2714
		/*
A
Andi Kleen 已提交
2715
		 * Other callers might not initialize the si_lsb field,
2716
		 * so check explicitly for the right codes here.
A
Andi Kleen 已提交
2717 2718 2719
		 */
		if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
L
Linus Torvalds 已提交
2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734
#endif
		break;
	case __SI_CHLD:
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		err |= __put_user(from->si_status, &to->si_status);
		err |= __put_user(from->si_utime, &to->si_utime);
		err |= __put_user(from->si_stime, &to->si_stime);
		break;
	case __SI_RT: /* This is not generated by the kernel as of now. */
	case __SI_MESGQ: /* But this is */
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		err |= __put_user(from->si_ptr, &to->si_ptr);
		break;
2735 2736 2737 2738 2739 2740 2741
#ifdef __ARCH_SIGSYS
	case __SI_SYS:
		err |= __put_user(from->si_call_addr, &to->si_call_addr);
		err |= __put_user(from->si_syscall, &to->si_syscall);
		err |= __put_user(from->si_arch, &to->si_arch);
		break;
#endif
L
Linus Torvalds 已提交
2742 2743 2744 2745 2746 2747 2748 2749 2750 2751
	default: /* this is just in case for now ... */
		err |= __put_user(from->si_pid, &to->si_pid);
		err |= __put_user(from->si_uid, &to->si_uid);
		break;
	}
	return err;
}

#endif

2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789
/**
 *  do_sigtimedwait - wait for queued signals specified in @which
 *  @which: queued signals to wait for
 *  @info: if non-null, the signal's siginfo is returned here
 *  @ts: upper bound on process time suspension
 */
int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
			const struct timespec *ts)
{
	struct task_struct *tsk = current;
	long timeout = MAX_SCHEDULE_TIMEOUT;
	sigset_t mask = *which;
	int sig;

	if (ts) {
		if (!timespec_valid(ts))
			return -EINVAL;
		timeout = timespec_to_jiffies(ts);
		/*
		 * We can be close to the next tick, add another one
		 * to ensure we will wait at least the time asked for.
		 */
		if (ts->tv_sec || ts->tv_nsec)
			timeout++;
	}

	/*
	 * 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);
	if (!sig && timeout) {
		/*
		 * None ready, temporarily unblock those we're interested
		 * while we are sleeping in so that we'll be awakened when
2790 2791
		 * they arrive. Unblocking is always fine, we can avoid
		 * set_current_blocked().
2792 2793 2794 2795 2796 2797 2798 2799 2800
		 */
		tsk->real_blocked = tsk->blocked;
		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
		recalc_sigpending();
		spin_unlock_irq(&tsk->sighand->siglock);

		timeout = schedule_timeout_interruptible(timeout);

		spin_lock_irq(&tsk->sighand->siglock);
2801
		__set_task_blocked(tsk, &tsk->real_blocked);
2802
		siginitset(&tsk->real_blocked, 0);
2803
		sig = dequeue_signal(tsk, &mask, info);
2804 2805 2806 2807 2808 2809 2810 2811
	}
	spin_unlock_irq(&tsk->sighand->siglock);

	if (sig)
		return sig;
	return timeout ? -EINTR : -EAGAIN;
}

2812 2813 2814 2815 2816 2817 2818 2819
/**
 *  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
 */
2820 2821 2822
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
2823 2824 2825 2826
{
	sigset_t these;
	struct timespec ts;
	siginfo_t info;
2827
	int ret;
L
Linus Torvalds 已提交
2828 2829 2830 2831 2832 2833 2834

	/* 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;
2835

L
Linus Torvalds 已提交
2836 2837 2838 2839 2840
	if (uts) {
		if (copy_from_user(&ts, uts, sizeof(ts)))
			return -EFAULT;
	}

2841
	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
L
Linus Torvalds 已提交
2842

2843 2844 2845
	if (ret > 0 && uinfo) {
		if (copy_siginfo_to_user(uinfo, &info))
			ret = -EFAULT;
L
Linus Torvalds 已提交
2846 2847 2848 2849 2850
	}

	return ret;
}

2851 2852 2853 2854 2855
/**
 *  sys_kill - send a signal to a process
 *  @pid: the PID of the process
 *  @sig: signal to be sent
 */
2856
SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2857 2858 2859 2860 2861 2862
{
	struct siginfo info;

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_USER;
2863
	info.si_pid = task_tgid_vnr(current);
2864
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
2865 2866 2867 2868

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

T
Thomas Gleixner 已提交
2869 2870
static int
do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
L
Linus Torvalds 已提交
2871 2872
{
	struct task_struct *p;
T
Thomas Gleixner 已提交
2873
	int error = -ESRCH;
L
Linus Torvalds 已提交
2874

2875
	rcu_read_lock();
2876
	p = find_task_by_vpid(pid);
2877
	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
T
Thomas Gleixner 已提交
2878
		error = check_kill_permission(sig, info, p);
L
Linus Torvalds 已提交
2879 2880 2881 2882
		/*
		 * The null signal is a permissions and process existence
		 * probe.  No signal is actually delivered.
		 */
2883 2884 2885 2886 2887 2888 2889 2890 2891
		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
2892 2893
		}
	}
2894
	rcu_read_unlock();
2895

L
Linus Torvalds 已提交
2896 2897 2898
	return error;
}

T
Thomas Gleixner 已提交
2899 2900 2901 2902 2903 2904 2905 2906
static int do_tkill(pid_t tgid, pid_t pid, int sig)
{
	struct siginfo info;

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_TKILL;
	info.si_pid = task_tgid_vnr(current);
2907
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
T
Thomas Gleixner 已提交
2908 2909 2910 2911

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

2912 2913 2914 2915 2916 2917
/**
 *  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
 *
2918
 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
2919 2920 2921
 *  exists but it's not belonging to the target process anymore. This
 *  method solves the problem of threads exiting and PIDs getting reused.
 */
2922
SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2923 2924 2925 2926 2927 2928 2929 2930
{
	/* This is only valid for single tasks */
	if (pid <= 0 || tgid <= 0)
		return -EINVAL;

	return do_tkill(tgid, pid, sig);
}

2931 2932 2933 2934 2935
/**
 *  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
2936 2937
 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
 */
2938
SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2939 2940 2941 2942 2943
{
	/* This is only valid for single tasks */
	if (pid <= 0)
		return -EINVAL;

2944
	return do_tkill(0, pid, sig);
L
Linus Torvalds 已提交
2945 2946
}

2947 2948 2949 2950 2951 2952
/**
 *  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
 */
2953 2954
SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
		siginfo_t __user *, uinfo)
L
Linus Torvalds 已提交
2955 2956 2957 2958 2959 2960 2961
{
	siginfo_t info;

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

	/* Not even root can pretend to send signals from the kernel.
2962 2963
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
2964
	if (info.si_code >= 0 || info.si_code == SI_TKILL) {
2965 2966
		/* We used to allow any < 0 si_code */
		WARN_ON_ONCE(info.si_code < 0);
L
Linus Torvalds 已提交
2967
		return -EPERM;
2968
	}
L
Linus Torvalds 已提交
2969 2970 2971 2972 2973 2974
	info.si_signo = sig;

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

2975 2976 2977 2978 2979 2980 2981
long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
{
	/* 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.
2982 2983
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
2984
	if (info->si_code >= 0 || info->si_code == SI_TKILL) {
2985 2986
		/* We used to allow any < 0 si_code */
		WARN_ON_ONCE(info->si_code < 0);
2987
		return -EPERM;
2988
	}
2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004
	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);
}

3005
int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
L
Linus Torvalds 已提交
3006
{
3007
	struct task_struct *t = current;
L
Linus Torvalds 已提交
3008
	struct k_sigaction *k;
3009
	sigset_t mask;
L
Linus Torvalds 已提交
3010

3011
	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
L
Linus Torvalds 已提交
3012 3013
		return -EINVAL;

3014
	k = &t->sighand->action[sig-1];
L
Linus Torvalds 已提交
3015 3016 3017 3018 3019 3020

	spin_lock_irq(&current->sighand->siglock);
	if (oact)
		*oact = *k;

	if (act) {
3021 3022
		sigdelsetmask(&act->sa.sa_mask,
			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3023
		*k = *act;
L
Linus Torvalds 已提交
3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034
		/*
		 * 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"
		 */
3035
		if (sig_handler_ignored(sig_handler(t, sig), sig)) {
3036 3037 3038
			sigemptyset(&mask);
			sigaddset(&mask, sig);
			rm_from_queue_full(&mask, &t->signal->shared_pending);
L
Linus Torvalds 已提交
3039
			do {
3040
				rm_from_queue_full(&mask, &t->pending);
L
Linus Torvalds 已提交
3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055
				t = next_thread(t);
			} while (t != current);
		}
	}

	spin_unlock_irq(&current->sighand->siglock);
	return 0;
}

int 
do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
{
	stack_t oss;
	int error;

3056 3057 3058
	oss.ss_sp = (void __user *) current->sas_ss_sp;
	oss.ss_size = current->sas_ss_size;
	oss.ss_flags = sas_ss_flags(sp);
L
Linus Torvalds 已提交
3059 3060 3061 3062 3063 3064 3065

	if (uss) {
		void __user *ss_sp;
		size_t ss_size;
		int ss_flags;

		error = -EFAULT;
L
Linus Torvalds 已提交
3066 3067 3068 3069 3070 3071
		if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
			goto out;
		error = __get_user(ss_sp, &uss->ss_sp) |
			__get_user(ss_flags, &uss->ss_flags) |
			__get_user(ss_size, &uss->ss_size);
		if (error)
L
Linus Torvalds 已提交
3072 3073 3074 3075 3076 3077 3078 3079
			goto out;

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

		error = -EINVAL;
		/*
3080
		 * Note - this code used to test ss_flags incorrectly:
L
Linus Torvalds 已提交
3081 3082 3083
		 *  	  old code may have been written using ss_flags==0
		 *	  to mean ss_flags==SS_ONSTACK (as this was the only
		 *	  way that worked) - this fix preserves that older
3084
		 *	  mechanism.
L
Linus Torvalds 已提交
3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101
		 */
		if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
			goto out;

		if (ss_flags == SS_DISABLE) {
			ss_size = 0;
			ss_sp = NULL;
		} else {
			error = -ENOMEM;
			if (ss_size < MINSIGSTKSZ)
				goto out;
		}

		current->sas_ss_sp = (unsigned long) ss_sp;
		current->sas_ss_size = ss_size;
	}

3102
	error = 0;
L
Linus Torvalds 已提交
3103 3104
	if (uoss) {
		error = -EFAULT;
3105
		if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
L
Linus Torvalds 已提交
3106
			goto out;
3107 3108 3109
		error = __put_user(oss.ss_sp, &uoss->ss_sp) |
			__put_user(oss.ss_size, &uoss->ss_size) |
			__put_user(oss.ss_flags, &uoss->ss_flags);
L
Linus Torvalds 已提交
3110 3111 3112 3113 3114 3115 3116 3117
	}

out:
	return error;
}

#ifdef __ARCH_WANT_SYS_SIGPENDING

3118 3119 3120 3121
/**
 *  sys_sigpending - examine pending signals
 *  @set: where mask of pending signal is returned
 */
3122
SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
L
Linus Torvalds 已提交
3123 3124 3125 3126 3127 3128 3129
{
	return do_sigpending(set, sizeof(*set));
}

#endif

#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3130 3131 3132
/**
 *  sys_sigprocmask - examine and change blocked signals
 *  @how: whether to add, remove, or set signals
3133
 *  @nset: signals to add or remove (if non-null)
3134 3135
 *  @oset: previous value of signal mask if non-null
 *
3136 3137 3138
 * Some platforms have their own version with special arguments;
 * others support only sys_rt_sigprocmask.
 */
L
Linus Torvalds 已提交
3139

3140
SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3141
		old_sigset_t __user *, oset)
L
Linus Torvalds 已提交
3142 3143
{
	old_sigset_t old_set, new_set;
3144
	sigset_t new_blocked;
L
Linus Torvalds 已提交
3145

3146
	old_set = current->blocked.sig[0];
L
Linus Torvalds 已提交
3147

3148 3149 3150
	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(*nset)))
			return -EFAULT;
L
Linus Torvalds 已提交
3151 3152
		new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));

3153
		new_blocked = current->blocked;
L
Linus Torvalds 已提交
3154 3155 3156

		switch (how) {
		case SIG_BLOCK:
3157
			sigaddsetmask(&new_blocked, new_set);
L
Linus Torvalds 已提交
3158 3159
			break;
		case SIG_UNBLOCK:
3160
			sigdelsetmask(&new_blocked, new_set);
L
Linus Torvalds 已提交
3161 3162
			break;
		case SIG_SETMASK:
3163
			new_blocked.sig[0] = new_set;
L
Linus Torvalds 已提交
3164
			break;
3165 3166
		default:
			return -EINVAL;
L
Linus Torvalds 已提交
3167 3168
		}

3169
		__set_current_blocked(&new_blocked);
3170 3171 3172
	}

	if (oset) {
L
Linus Torvalds 已提交
3173
		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3174
			return -EFAULT;
L
Linus Torvalds 已提交
3175
	}
3176 3177

	return 0;
L
Linus Torvalds 已提交
3178 3179 3180 3181
}
#endif /* __ARCH_WANT_SYS_SIGPROCMASK */

#ifdef __ARCH_WANT_SYS_RT_SIGACTION
3182 3183 3184
/**
 *  sys_rt_sigaction - alter an action taken by a process
 *  @sig: signal to be sent
3185 3186
 *  @act: new sigaction
 *  @oact: used to save the previous sigaction
3187 3188
 *  @sigsetsize: size of sigset_t type
 */
3189 3190 3191 3192
SYSCALL_DEFINE4(rt_sigaction, int, sig,
		const struct sigaction __user *, act,
		struct sigaction __user *, oact,
		size_t, sigsetsize)
L
Linus Torvalds 已提交
3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221
{
	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;
}
#endif /* __ARCH_WANT_SYS_RT_SIGACTION */

#ifdef __ARCH_WANT_SYS_SGETMASK

/*
 * For backwards compatibility.  Functionality superseded by sigprocmask.
 */
3222
SYSCALL_DEFINE0(sgetmask)
L
Linus Torvalds 已提交
3223 3224 3225 3226 3227
{
	/* SMP safe */
	return current->blocked.sig[0];
}

3228
SYSCALL_DEFINE1(ssetmask, int, newmask)
L
Linus Torvalds 已提交
3229
{
3230 3231
	int old = current->blocked.sig[0];
	sigset_t newset;
L
Linus Torvalds 已提交
3232

3233
	set_current_blocked(&newset);
L
Linus Torvalds 已提交
3234 3235 3236 3237 3238 3239 3240 3241 3242

	return old;
}
#endif /* __ARCH_WANT_SGETMASK */

#ifdef __ARCH_WANT_SYS_SIGNAL
/*
 * For backwards compatibility.  Functionality superseded by sigaction.
 */
3243
SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
L
Linus Torvalds 已提交
3244 3245 3246 3247 3248 3249
{
	struct k_sigaction new_sa, old_sa;
	int ret;

	new_sa.sa.sa_handler = handler;
	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3250
	sigemptyset(&new_sa.sa.sa_mask);
L
Linus Torvalds 已提交
3251 3252 3253 3254 3255 3256 3257 3258 3259

	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

3260
SYSCALL_DEFINE0(pause)
L
Linus Torvalds 已提交
3261
{
3262 3263 3264 3265
	while (!signal_pending(current)) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
	}
L
Linus Torvalds 已提交
3266 3267 3268 3269 3270
	return -ERESTARTNOHAND;
}

#endif

A
Al Viro 已提交
3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281
int sigsuspend(sigset_t *set)
{
	current->saved_sigmask = current->blocked;
	set_current_blocked(set);

	current->state = TASK_INTERRUPTIBLE;
	schedule();
	set_restore_sigmask();
	return -ERESTARTNOHAND;
}

3282
#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
3283 3284 3285 3286 3287 3288
/**
 *  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
 */
3289
SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3290 3291 3292 3293 3294 3295 3296 3297 3298
{
	sigset_t newset;

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

	if (copy_from_user(&newset, unewset, sizeof(newset)))
		return -EFAULT;
A
Al Viro 已提交
3299
	return sigsuspend(&newset);
3300 3301 3302
}
#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */

3303 3304 3305 3306 3307
__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
{
	return NULL;
}

L
Linus Torvalds 已提交
3308 3309
void __init signals_init(void)
{
3310
	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
L
Linus Torvalds 已提交
3311
}
3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351

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