signal.c 94.7 KB
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/*
 *  linux/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
 *
 *  2003-06-02  Jim Houston - Concurrent Computer Corp.
 *		Changes to use preallocated sigqueue structures
 *		to allow signals to be sent reliably.
 */

#include <linux/slab.h>
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#include <linux/export.h>
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#include <linux/init.h>
#include <linux/sched.h>
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#include <linux/sched/user.h>
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#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
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#include <linux/coredump.h>
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#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/ptrace.h>
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#include <linux/signal.h>
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#include <linux/signalfd.h>
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#include <linux/ratelimit.h>
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#include <linux/tracehook.h>
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#include <linux/capability.h>
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#include <linux/freezer.h>
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#include <linux/pid_namespace.h>
#include <linux/nsproxy.h>
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#include <linux/user_namespace.h>
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#include <linux/uprobes.h>
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#include <linux/compat.h>
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#include <linux/cn_proc.h>
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#include <linux/compiler.h>

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

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static struct kmem_cache *sigqueue_cachep;
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int print_fatal_signals __read_mostly;

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

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

	return sig_handler_ignored(handler, sig);
}

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

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

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

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

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

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

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

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

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

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

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

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

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}

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

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

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

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

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

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

	if (!print_fatal_signals)
		return;

	if (!__ratelimit(&ratelimit_state))
		return;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	flush_signals(t);
}

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

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

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

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

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

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

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

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

			if (!hrtimer_is_queued(tmr) &&
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			    tsk->signal->it_real_incr != 0) {
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				hrtimer_forward(tmr, tmr->base->get_time(),
						tsk->signal->it_real_incr);
				hrtimer_restart(tmr);
			}
		}
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#endif
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	}
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	recalc_sigpending();
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	if (!signr)
		return 0;

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

660 661 662 663 664 665
/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 */
666
static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s)
667 668 669 670 671 672 673 674
{
	struct sigqueue *q, *n;
	sigset_t m;

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

675
	sigandnsets(&s->signal, &s->signal, mask);
676 677 678 679 680 681 682 683
	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
684

685 686 687 688 689 690 691 692 693 694 695
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));
}

696 697 698 699 700 701 702 703
/*
 * 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);

704 705 706 707
	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))
708 709
		return 1;

710
	if (ns_capable(tcred->user_ns, CAP_KILL))
711 712 713 714 715
		return 1;

	return 0;
}

L
Linus Torvalds 已提交
716 717
/*
 * Bad permissions for sending the signal
718
 * - the caller must hold the RCU read lock
L
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719 720 721 722
 */
static int check_kill_permission(int sig, struct siginfo *info,
				 struct task_struct *t)
{
723
	struct pid *sid;
724 725
	int error;

726
	if (!valid_signal(sig))
727 728
		return -EINVAL;

729
	if (!si_fromuser(info))
730
		return 0;
A
Amy Griffis 已提交
731

732 733
	error = audit_signal_info(sig, t); /* Let audit system see the signal */
	if (error)
L
Linus Torvalds 已提交
734
		return error;
735

736
	if (!same_thread_group(current, t) &&
737
	    !kill_ok_by_cred(t)) {
738 739 740 741 742 743 744 745 746 747 748 749 750
		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;
		}
	}
751

A
Amy Griffis 已提交
752
	return security_task_kill(t, info, sig, 0);
L
Linus Torvalds 已提交
753 754
}

755 756 757 758 759 760 761 762
/**
 * 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
763 764 765 766 767
 * 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.
768 769 770 771 772 773 774 775 776 777
 *
 * 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);
778
	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
779 780
}

L
Linus Torvalds 已提交
781
/*
782 783
 * 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
784 785
 * time regardless of blocking, ignoring, or handling.  This does the
 * actual continuing for SIGCONT, but not the actual stopping for stop
786 787 788 789
 * 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
790
 */
791
static bool prepare_signal(int sig, struct task_struct *p, bool force)
L
Linus Torvalds 已提交
792
{
793
	struct signal_struct *signal = p->signal;
L
Linus Torvalds 已提交
794
	struct task_struct *t;
795
	sigset_t flush;
L
Linus Torvalds 已提交
796

797
	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
798
		if (!(signal->flags & SIGNAL_GROUP_EXIT))
799
			return sig == SIGKILL;
L
Linus Torvalds 已提交
800
		/*
801
		 * The process is in the middle of dying, nothing to do.
L
Linus Torvalds 已提交
802
		 */
803
	} else if (sig_kernel_stop(sig)) {
L
Linus Torvalds 已提交
804 805 806
		/*
		 * This is a stop signal.  Remove SIGCONT from all queues.
		 */
807
		siginitset(&flush, sigmask(SIGCONT));
808
		flush_sigqueue_mask(&flush, &signal->shared_pending);
809
		for_each_thread(p, t)
810
			flush_sigqueue_mask(&flush, &t->pending);
L
Linus Torvalds 已提交
811
	} else if (sig == SIGCONT) {
812
		unsigned int why;
L
Linus Torvalds 已提交
813
		/*
814
		 * Remove all stop signals from all queues, wake all threads.
L
Linus Torvalds 已提交
815
		 */
816
		siginitset(&flush, SIG_KERNEL_STOP_MASK);
817
		flush_sigqueue_mask(&flush, &signal->shared_pending);
818
		for_each_thread(p, t) {
819
			flush_sigqueue_mask(&flush, &t->pending);
820
			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
821 822 823 824
			if (likely(!(t->ptrace & PT_SEIZED)))
				wake_up_state(t, __TASK_STOPPED);
			else
				ptrace_trap_notify(t);
825
		}
L
Linus Torvalds 已提交
826

827 828 829 830 831 832 833 834 835
		/*
		 * 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;
836
		if (signal->flags & SIGNAL_STOP_STOPPED)
837
			why |= SIGNAL_CLD_CONTINUED;
838
		else if (signal->group_stop_count)
839 840 841
			why |= SIGNAL_CLD_STOPPED;

		if (why) {
842
			/*
843
			 * The first thread which returns from do_signal_stop()
844 845 846
			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
			 * notify its parent. See get_signal_to_deliver().
			 */
847
			signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED);
848 849
			signal->group_stop_count = 0;
			signal->group_exit_code = 0;
L
Linus Torvalds 已提交
850 851
		}
	}
852

853
	return !sig_ignored(p, sig, force);
L
Linus Torvalds 已提交
854 855
}

856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876
/*
 * 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);
}

877
static void complete_signal(int sig, struct task_struct *p, int group)
878 879 880 881 882 883 884 885 886 887 888 889
{
	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;
890
	else if (!group || thread_group_empty(p))
891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917
		/*
		 * 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.
	 */
918 919
	if (sig_fatal(p, sig) &&
	    !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
920
	    !sigismember(&t->real_blocked, sig) &&
T
Tejun Heo 已提交
921
	    (sig == SIGKILL || !t->ptrace)) {
922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
		/*
		 * 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 {
937
				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
938 939 940 941 942 943 944 945 946 947 948 949 950 951 952
				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;
}

953 954 955 956 957
static inline int legacy_queue(struct sigpending *signals, int sig)
{
	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
}

958 959 960 961 962 963 964 965 966
#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;

967 968 969 970
	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();
971 972 973 974 975 976 977 978
}
#else
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
{
	return;
}
#endif

979 980
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
981
{
982
	struct sigpending *pending;
983
	struct sigqueue *q;
984
	int override_rlimit;
985
	int ret = 0, result;
986

987
	assert_spin_locked(&t->sighand->siglock);
988

989
	result = TRACE_SIGNAL_IGNORED;
990 991
	if (!prepare_signal(sig, t,
			from_ancestor_ns || (info == SEND_SIG_FORCED)))
992
		goto ret;
993 994

	pending = group ? &t->signal->shared_pending : &t->pending;
995 996 997 998 999
	/*
	 * 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.
	 */
1000
	result = TRACE_SIGNAL_ALREADY_PENDING;
1001
	if (legacy_queue(pending, sig))
1002 1003 1004
		goto ret;

	result = TRACE_SIGNAL_DELIVERED;
L
Linus Torvalds 已提交
1005 1006 1007 1008
	/*
	 * fast-pathed signals for kernel-internal things like SIGSTOP
	 * or SIGKILL.
	 */
1009
	if (info == SEND_SIG_FORCED)
L
Linus Torvalds 已提交
1010 1011
		goto out_set;

1012 1013 1014 1015 1016 1017 1018 1019 1020
	/*
	 * 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.
	 */
1021 1022 1023 1024 1025
	if (sig < SIGRTMIN)
		override_rlimit = (is_si_special(info) || info->si_code >= 0);
	else
		override_rlimit = 0;

1026
	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
1027
		override_rlimit);
L
Linus Torvalds 已提交
1028
	if (q) {
1029
		list_add_tail(&q->list, &pending->list);
L
Linus Torvalds 已提交
1030
		switch ((unsigned long) info) {
1031
		case (unsigned long) SEND_SIG_NOINFO:
L
Linus Torvalds 已提交
1032 1033 1034
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_USER;
1035
			q->info.si_pid = task_tgid_nr_ns(current,
1036
							task_active_pid_ns(t));
1037
			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1038
			break;
1039
		case (unsigned long) SEND_SIG_PRIV:
L
Linus Torvalds 已提交
1040 1041 1042 1043 1044 1045 1046 1047
			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);
1048 1049
			if (from_ancestor_ns)
				q->info.si_pid = 0;
L
Linus Torvalds 已提交
1050 1051
			break;
		}
1052 1053 1054

		userns_fixup_signal_uid(&q->info, t);

1055
	} else if (!is_si_special(info)) {
1056 1057 1058 1059 1060 1061
		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().
			 */
1062 1063 1064
			result = TRACE_SIGNAL_OVERFLOW_FAIL;
			ret = -EAGAIN;
			goto ret;
1065 1066 1067 1068 1069
		} else {
			/*
			 * This is a silent loss of information.  We still
			 * send the signal, but the *info bits are lost.
			 */
1070
			result = TRACE_SIGNAL_LOSE_INFO;
1071
		}
L
Linus Torvalds 已提交
1072 1073 1074
	}

out_set:
1075
	signalfd_notify(t, sig);
1076
	sigaddset(&pending->signal, sig);
1077
	complete_signal(sig, t, group);
1078 1079 1080
ret:
	trace_signal_generate(sig, info, t, group, result);
	return ret;
L
Linus Torvalds 已提交
1081 1082
}

1083 1084 1085
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
			int group)
{
1086 1087 1088
	int from_ancestor_ns = 0;

#ifdef CONFIG_PID_NS
1089 1090
	from_ancestor_ns = si_fromuser(info) &&
			   !task_pid_nr_ns(current, task_active_pid_ns(t));
1091 1092 1093
#endif

	return __send_signal(sig, info, t, group, from_ancestor_ns);
1094 1095
}

1096
static void print_fatal_signal(int signr)
I
Ingo Molnar 已提交
1097
{
1098
	struct pt_regs *regs = signal_pt_regs();
1099
	pr_info("potentially unexpected fatal signal %d.\n", signr);
I
Ingo Molnar 已提交
1100

A
Al Viro 已提交
1101
#if defined(__i386__) && !defined(__arch_um__)
1102
	pr_info("code at %08lx: ", regs->ip);
I
Ingo Molnar 已提交
1103 1104 1105 1106 1107
	{
		int i;
		for (i = 0; i < 16; i++) {
			unsigned char insn;

1108 1109
			if (get_user(insn, (unsigned char *)(regs->ip + i)))
				break;
1110
			pr_cont("%02x ", insn);
I
Ingo Molnar 已提交
1111 1112
		}
	}
1113
	pr_cont("\n");
I
Ingo Molnar 已提交
1114
#endif
1115
	preempt_disable();
I
Ingo Molnar 已提交
1116
	show_regs(regs);
1117
	preempt_enable();
I
Ingo Molnar 已提交
1118 1119 1120 1121 1122 1123 1124 1125 1126 1127
}

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
1128

1129 1130 1131 1132 1133 1134
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
1135 1136 1137
static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
1138
	return send_signal(sig, info, t, 0);
L
Linus Torvalds 已提交
1139 1140
}

1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154
int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
			bool group)
{
	unsigned long flags;
	int ret = -ESRCH;

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

	return ret;
}

L
Linus Torvalds 已提交
1155 1156 1157
/*
 * Force a signal that the process can't ignore: if necessary
 * we unblock the signal and change any SIG_IGN to SIG_DFL.
1158 1159 1160 1161 1162
 *
 * 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.
 *
1163 1164
 * We don't want to have recursive SIGSEGV's etc, for example,
 * that is why we also clear SIGNAL_UNKILLABLE.
L
Linus Torvalds 已提交
1165 1166 1167 1168 1169
 */
int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
	unsigned long int flags;
1170 1171
	int ret, blocked, ignored;
	struct k_sigaction *action;
L
Linus Torvalds 已提交
1172 1173

	spin_lock_irqsave(&t->sighand->siglock, flags);
1174 1175 1176 1177 1178 1179 1180
	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
1181
			recalc_sigpending_and_wake(t);
1182
		}
L
Linus Torvalds 已提交
1183
	}
1184 1185
	if (action->sa.sa_handler == SIG_DFL)
		t->signal->flags &= ~SIGNAL_UNKILLABLE;
L
Linus Torvalds 已提交
1186 1187 1188 1189 1190 1191 1192 1193 1194
	ret = specific_send_sig_info(sig, info, t);
	spin_unlock_irqrestore(&t->sighand->siglock, flags);

	return ret;
}

/*
 * Nuke all other threads in the group.
 */
1195
int zap_other_threads(struct task_struct *p)
L
Linus Torvalds 已提交
1196
{
1197 1198
	struct task_struct *t = p;
	int count = 0;
L
Linus Torvalds 已提交
1199 1200 1201

	p->signal->group_stop_count = 0;

1202
	while_each_thread(p, t) {
1203
		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1204 1205 1206
		count++;

		/* Don't bother with already dead threads */
L
Linus Torvalds 已提交
1207 1208 1209 1210 1211
		if (t->exit_state)
			continue;
		sigaddset(&t->pending.signal, SIGKILL);
		signal_wake_up(t, 1);
	}
1212 1213

	return count;
L
Linus Torvalds 已提交
1214 1215
}

1216 1217
struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
					   unsigned long *flags)
1218 1219 1220 1221
{
	struct sighand_struct *sighand;

	for (;;) {
1222 1223 1224 1225
		/*
		 * Disable interrupts early to avoid deadlocks.
		 * See rcu_read_unlock() comment header for details.
		 */
1226 1227
		local_irq_save(*flags);
		rcu_read_lock();
1228
		sighand = rcu_dereference(tsk->sighand);
1229 1230 1231
		if (unlikely(sighand == NULL)) {
			rcu_read_unlock();
			local_irq_restore(*flags);
1232
			break;
1233
		}
1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244
		/*
		 * This sighand can be already freed and even reused, but
		 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
		 * initializes ->siglock: this slab can't go away, it has
		 * the same object type, ->siglock can't be reinitialized.
		 *
		 * We need to ensure that tsk->sighand is still the same
		 * after we take the lock, we can race with de_thread() or
		 * __exit_signal(). In the latter case the next iteration
		 * must see ->sighand == NULL.
		 */
1245 1246 1247
		spin_lock(&sighand->siglock);
		if (likely(sighand == tsk->sighand)) {
			rcu_read_unlock();
1248
			break;
1249 1250 1251 1252
		}
		spin_unlock(&sighand->siglock);
		rcu_read_unlock();
		local_irq_restore(*flags);
1253 1254 1255 1256 1257
	}

	return sighand;
}

1258 1259 1260
/*
 * send signal info to all the members of a group
 */
L
Linus Torvalds 已提交
1261 1262
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
1263 1264 1265 1266 1267
	int ret;

	rcu_read_lock();
	ret = check_kill_permission(sig, info, p);
	rcu_read_unlock();
1268

1269 1270
	if (!ret && sig)
		ret = do_send_sig_info(sig, info, p, true);
L
Linus Torvalds 已提交
1271 1272 1273 1274 1275

	return ret;
}

/*
1276
 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
L
Linus Torvalds 已提交
1277
 * control characters do (^C, ^Z etc)
1278
 * - the caller must hold at least a readlock on tasklist_lock
L
Linus Torvalds 已提交
1279
 */
1280
int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
L
Linus Torvalds 已提交
1281 1282 1283 1284 1285 1286
{
	struct task_struct *p = NULL;
	int retval, success;

	success = 0;
	retval = -ESRCH;
1287
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
L
Linus Torvalds 已提交
1288 1289 1290
		int err = group_send_sig_info(sig, info, p);
		success |= !err;
		retval = err;
1291
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
L
Linus Torvalds 已提交
1292 1293 1294
	return success ? 0 : retval;
}

1295
int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
L
Linus Torvalds 已提交
1296
{
1297
	int error = -ESRCH;
L
Linus Torvalds 已提交
1298 1299
	struct task_struct *p;

1300 1301 1302 1303 1304 1305 1306 1307
	for (;;) {
		rcu_read_lock();
		p = pid_task(pid, PIDTYPE_PID);
		if (p)
			error = group_send_sig_info(sig, info, p);
		rcu_read_unlock();
		if (likely(!p || error != -ESRCH))
			return error;
1308

1309 1310 1311 1312 1313 1314
		/*
		 * The task was unhashed in between, try again.  If it
		 * is dead, pid_task() will return NULL, if we race with
		 * de_thread() it will find the new leader.
		 */
	}
L
Linus Torvalds 已提交
1315 1316
}

1317
int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1318 1319 1320
{
	int error;
	rcu_read_lock();
1321
	error = kill_pid_info(sig, info, find_vpid(pid));
1322 1323 1324 1325
	rcu_read_unlock();
	return error;
}

1326 1327 1328 1329
static int kill_as_cred_perm(const struct cred *cred,
			     struct task_struct *target)
{
	const struct cred *pcred = __task_cred(target);
1330 1331
	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))
1332 1333 1334 1335
		return 0;
	return 1;
}

1336
/* like kill_pid_info(), but doesn't use uid/euid of "current" */
1337 1338
int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
			 const struct cred *cred, u32 secid)
1339 1340 1341
{
	int ret = -EINVAL;
	struct task_struct *p;
1342
	unsigned long flags;
1343 1344 1345 1346

	if (!valid_signal(sig))
		return ret;

1347
	rcu_read_lock();
1348
	p = pid_task(pid, PIDTYPE_PID);
1349 1350 1351 1352
	if (!p) {
		ret = -ESRCH;
		goto out_unlock;
	}
1353
	if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
1354 1355 1356
		ret = -EPERM;
		goto out_unlock;
	}
1357 1358 1359
	ret = security_task_kill(p, info, sig, secid);
	if (ret)
		goto out_unlock;
1360 1361 1362 1363 1364 1365 1366

	if (sig) {
		if (lock_task_sighand(p, &flags)) {
			ret = __send_signal(sig, info, p, 1, 0);
			unlock_task_sighand(p, &flags);
		} else
			ret = -ESRCH;
1367 1368
	}
out_unlock:
1369
	rcu_read_unlock();
1370 1371
	return ret;
}
1372
EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
L
Linus Torvalds 已提交
1373 1374 1375 1376 1377 1378 1379 1380

/*
 * 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.
 */

1381
static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
L
Linus Torvalds 已提交
1382
{
1383
	int ret;
1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396

	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
1397 1398 1399 1400
		int retval = 0, count = 0;
		struct task_struct * p;

		for_each_process(p) {
1401 1402
			if (task_pid_vnr(p) > 1 &&
					!same_thread_group(p, current)) {
L
Linus Torvalds 已提交
1403 1404 1405 1406 1407 1408
				int err = group_send_sig_info(sig, info, p);
				++count;
				if (err != -EPERM)
					retval = err;
			}
		}
1409
		ret = count ? retval : -ESRCH;
L
Linus Torvalds 已提交
1410
	}
1411 1412
	read_unlock(&tasklist_lock);

1413
	return ret;
L
Linus Torvalds 已提交
1414 1415 1416 1417 1418 1419
}

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

1420
int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
L
Linus Torvalds 已提交
1421 1422 1423 1424 1425
{
	/*
	 * Make sure legacy kernel users don't send in bad values
	 * (normal paths check this in check_kill_permission).
	 */
1426
	if (!valid_signal(sig))
L
Linus Torvalds 已提交
1427 1428
		return -EINVAL;

1429
	return do_send_sig_info(sig, info, p, false);
L
Linus Torvalds 已提交
1430 1431
}

1432 1433 1434
#define __si_special(priv) \
	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)

L
Linus Torvalds 已提交
1435 1436 1437
int
send_sig(int sig, struct task_struct *p, int priv)
{
1438
	return send_sig_info(sig, __si_special(priv), p);
L
Linus Torvalds 已提交
1439 1440 1441 1442 1443
}

void
force_sig(int sig, struct task_struct *p)
{
1444
	force_sig_info(sig, SEND_SIG_PRIV, p);
L
Linus Torvalds 已提交
1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465
}

/*
 * 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;
}

1466 1467
int kill_pgrp(struct pid *pid, int sig, int priv)
{
1468 1469 1470 1471 1472 1473 1474
	int ret;

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

	return ret;
1475 1476 1477 1478 1479 1480 1481 1482 1483
}
EXPORT_SYMBOL(kill_pgrp);

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

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

1497
	if (q)
L
Linus Torvalds 已提交
1498
		q->flags |= SIGQUEUE_PREALLOC;
1499 1500

	return q;
L
Linus Torvalds 已提交
1501 1502 1503 1504 1505
}

void sigqueue_free(struct sigqueue *q)
{
	unsigned long flags;
1506 1507
	spinlock_t *lock = &current->sighand->siglock;

L
Linus Torvalds 已提交
1508 1509
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
	/*
1510 1511
	 * We must hold ->siglock while testing q->list
	 * to serialize with collect_signal() or with
1512
	 * __exit_signal()->flush_sigqueue().
L
Linus Torvalds 已提交
1513
	 */
1514
	spin_lock_irqsave(lock, flags);
1515 1516 1517 1518 1519
	q->flags &= ~SIGQUEUE_PREALLOC;
	/*
	 * If it is queued it will be freed when dequeued,
	 * like the "regular" sigqueue.
	 */
1520
	if (!list_empty(&q->list))
1521
		q = NULL;
1522 1523
	spin_unlock_irqrestore(lock, flags);

1524 1525
	if (q)
		__sigqueue_free(q);
L
Linus Torvalds 已提交
1526 1527
}

1528
int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
1529
{
1530
	int sig = q->info.si_signo;
1531
	struct sigpending *pending;
1532
	unsigned long flags;
1533
	int ret, result;
1534

1535
	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1536 1537 1538 1539 1540

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

1541
	ret = 1; /* the signal is ignored */
1542
	result = TRACE_SIGNAL_IGNORED;
1543
	if (!prepare_signal(sig, t, false))
1544 1545 1546
		goto out;

	ret = 0;
1547 1548 1549 1550 1551 1552 1553
	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++;
1554
		result = TRACE_SIGNAL_ALREADY_PENDING;
1555
		goto out;
1556
	}
1557
	q->info.si_overrun = 0;
1558 1559

	signalfd_notify(t, sig);
1560
	pending = group ? &t->signal->shared_pending : &t->pending;
1561 1562
	list_add_tail(&q->list, &pending->list);
	sigaddset(&pending->signal, sig);
1563
	complete_signal(sig, t, group);
1564
	result = TRACE_SIGNAL_DELIVERED;
1565
out:
1566
	trace_signal_generate(sig, &q->info, t, group, result);
1567 1568 1569
	unlock_task_sighand(t, &flags);
ret:
	return ret;
1570 1571
}

L
Linus Torvalds 已提交
1572 1573 1574
/*
 * 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
1575
 *
1576 1577
 * Returns true if our parent ignored us and so we've switched to
 * self-reaping.
L
Linus Torvalds 已提交
1578
 */
1579
bool do_notify_parent(struct task_struct *tsk, int sig)
L
Linus Torvalds 已提交
1580 1581 1582 1583
{
	struct siginfo info;
	unsigned long flags;
	struct sighand_struct *psig;
1584
	bool autoreap = false;
1585
	u64 utime, stime;
L
Linus Torvalds 已提交
1586 1587 1588 1589

	BUG_ON(sig == -1);

 	/* do_notify_parent_cldstop should have been called instead.  */
M
Matthew Wilcox 已提交
1590
 	BUG_ON(task_is_stopped_or_traced(tsk));
L
Linus Torvalds 已提交
1591

T
Tejun Heo 已提交
1592
	BUG_ON(!tsk->ptrace &&
L
Linus Torvalds 已提交
1593 1594
	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));

1595 1596 1597 1598 1599 1600 1601 1602 1603
	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
1604 1605
	info.si_signo = sig;
	info.si_errno = 0;
1606
	/*
1607 1608
	 * We are under tasklist_lock here so our parent is tied to
	 * us and cannot change.
1609
	 *
1610 1611
	 * task_active_pid_ns will always return the same pid namespace
	 * until a task passes through release_task.
1612 1613 1614 1615 1616 1617
	 *
	 * 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();
1618
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent));
1619 1620
	info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
				       task_uid(tsk));
1621 1622
	rcu_read_unlock();

1623 1624 1625
	task_cputime(tsk, &utime, &stime);
	info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime);
	info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime);
L
Linus Torvalds 已提交
1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638

	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
1639
	if (!tsk->ptrace && sig == SIGCHLD &&
L
Linus Torvalds 已提交
1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656
	    (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).
		 */
1657
		autoreap = true;
L
Linus Torvalds 已提交
1658
		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1659
			sig = 0;
L
Linus Torvalds 已提交
1660
	}
1661
	if (valid_signal(sig) && sig)
L
Linus Torvalds 已提交
1662 1663 1664
		__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
1665

1666
	return autoreap;
L
Linus Torvalds 已提交
1667 1668
}

1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683
/**
 * 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
1684 1685 1686
{
	struct siginfo info;
	unsigned long flags;
1687
	struct task_struct *parent;
L
Linus Torvalds 已提交
1688
	struct sighand_struct *sighand;
1689
	u64 utime, stime;
L
Linus Torvalds 已提交
1690

1691
	if (for_ptracer) {
1692
		parent = tsk->parent;
1693
	} else {
1694 1695 1696 1697
		tsk = tsk->group_leader;
		parent = tsk->real_parent;
	}

L
Linus Torvalds 已提交
1698 1699
	info.si_signo = SIGCHLD;
	info.si_errno = 0;
1700
	/*
1701
	 * see comment in do_notify_parent() about the following 4 lines
1702 1703
	 */
	rcu_read_lock();
1704
	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
1705
	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
1706 1707
	rcu_read_unlock();

1708 1709 1710
	task_cputime(tsk, &utime, &stime);
	info.si_utime = nsec_to_clock_t(utime);
	info.si_stime = nsec_to_clock_t(stime);
L
Linus Torvalds 已提交
1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738

 	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);
}

1739 1740
static inline int may_ptrace_stop(void)
{
T
Tejun Heo 已提交
1741
	if (!likely(current->ptrace))
1742 1743 1744 1745 1746 1747 1748
		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
1749
	 * ->siglock we must see ->core_state != NULL. Otherwise it
1750
	 * is safe to enter schedule().
1751 1752 1753 1754
	 *
	 * This is almost outdated, a task with the pending SIGKILL can't
	 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
	 * after SIGKILL was already dequeued.
1755
	 */
1756
	if (unlikely(current->mm->core_state) &&
1757 1758 1759 1760 1761 1762
	    unlikely(current->mm == current->parent->mm))
		return 0;

	return 1;
}

R
Roland McGrath 已提交
1763
/*
1764
 * Return non-zero if there is a SIGKILL that should be waking us up.
R
Roland McGrath 已提交
1765 1766 1767 1768
 * Called with the siglock held.
 */
static int sigkill_pending(struct task_struct *tsk)
{
1769 1770
	return	sigismember(&tsk->pending.signal, SIGKILL) ||
		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
R
Roland McGrath 已提交
1771 1772
}

L
Linus Torvalds 已提交
1773 1774 1775 1776 1777 1778 1779 1780
/*
 * 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.
 *
1781 1782
 * 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
1783
 */
T
Tejun Heo 已提交
1784
static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
1785 1786
	__releases(&current->sighand->siglock)
	__acquires(&current->sighand->siglock)
L
Linus Torvalds 已提交
1787
{
1788 1789
	bool gstop_done = false;

R
Roland McGrath 已提交
1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804
	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);
1805 1806
		if (sigkill_pending(current))
			return;
R
Roland McGrath 已提交
1807 1808
	}

L
Linus Torvalds 已提交
1809
	/*
1810 1811 1812 1813 1814
	 * 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
1815
	 */
1816
	set_current_state(TASK_TRACED);
L
Linus Torvalds 已提交
1817 1818 1819 1820

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

1821
	/*
1822 1823
	 * If @why is CLD_STOPPED, we're trapping to participate in a group
	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
1824 1825 1826
	 * 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.
1827
	 */
1828
	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
1829
		gstop_done = task_participate_group_stop(current);
1830

1831
	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
1832
	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
1833 1834
	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
1835

1836
	/* entering a trap, clear TRAPPING */
1837
	task_clear_jobctl_trapping(current);
1838

L
Linus Torvalds 已提交
1839 1840
	spin_unlock_irq(&current->sighand->siglock);
	read_lock(&tasklist_lock);
1841
	if (may_ptrace_stop()) {
1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852
		/*
		 * 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);
1853
		if (gstop_done && ptrace_reparented(current))
1854 1855
			do_notify_parent_cldstop(current, false, why);

M
Miklos Szeredi 已提交
1856 1857 1858 1859 1860 1861 1862
		/*
		 * 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
1863
		read_unlock(&tasklist_lock);
M
Miklos Szeredi 已提交
1864
		preempt_enable_no_resched();
1865
		freezable_schedule();
L
Linus Torvalds 已提交
1866 1867 1868
	} else {
		/*
		 * By the time we got the lock, our tracer went away.
1869
		 * Don't drop the lock yet, another tracer may come.
1870 1871 1872
		 *
		 * If @gstop_done, the ptracer went away between group stop
		 * completion and here.  During detach, it would have set
1873 1874 1875
		 * 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
1876
		 */
1877 1878 1879
		if (gstop_done)
			do_notify_parent_cldstop(current, false, why);

1880
		/* tasklist protects us from ptrace_freeze_traced() */
1881
		__set_current_state(TASK_RUNNING);
1882 1883
		if (clear_code)
			current->exit_code = 0;
1884
		read_unlock(&tasklist_lock);
L
Linus Torvalds 已提交
1885 1886 1887 1888 1889 1890 1891 1892 1893 1894
	}

	/*
	 * 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
1895 1896 1897
	/* LISTENING can be set only during STOP traps, clear it */
	current->jobctl &= ~JOBCTL_LISTENING;

L
Linus Torvalds 已提交
1898 1899 1900
	/*
	 * Queued signals ignored us while we were stopped for tracing.
	 * So check for any that we should take before resuming user mode.
1901
	 * This sets TIF_SIGPENDING, but never clears it.
L
Linus Torvalds 已提交
1902
	 */
1903
	recalc_sigpending_tsk(current);
L
Linus Torvalds 已提交
1904 1905
}

T
Tejun Heo 已提交
1906
static void ptrace_do_notify(int signr, int exit_code, int why)
L
Linus Torvalds 已提交
1907 1908 1909 1910
{
	siginfo_t info;

	memset(&info, 0, sizeof info);
T
Tejun Heo 已提交
1911
	info.si_signo = signr;
L
Linus Torvalds 已提交
1912
	info.si_code = exit_code;
1913
	info.si_pid = task_pid_vnr(current);
1914
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
1915 1916

	/* Let the debugger run.  */
T
Tejun Heo 已提交
1917 1918 1919 1920 1921 1922
	ptrace_stop(exit_code, why, 1, &info);
}

void ptrace_notify(int exit_code)
{
	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1923 1924
	if (unlikely(current->task_works))
		task_work_run();
T
Tejun Heo 已提交
1925

L
Linus Torvalds 已提交
1926
	spin_lock_irq(&current->sighand->siglock);
T
Tejun Heo 已提交
1927
	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
L
Linus Torvalds 已提交
1928 1929 1930
	spin_unlock_irq(&current->sighand->siglock);
}

1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951
/**
 * 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
1952
 */
1953 1954
static bool do_signal_stop(int signr)
	__releases(&current->sighand->siglock)
L
Linus Torvalds 已提交
1955 1956 1957
{
	struct signal_struct *sig = current->signal;

1958
	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
1959
		unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
1960 1961
		struct task_struct *t;

1962 1963
		/* signr will be recorded in task->jobctl for retries */
		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
1964

1965
		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
1966
		    unlikely(signal_group_exit(sig)))
1967
			return false;
L
Linus Torvalds 已提交
1968
		/*
1969 1970 1971 1972 1973 1974 1975
		 * 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
1976 1977
		 * cause two group stops when !ptraced.  That is why we
		 * also check !task_is_stopped(t) below.
1978 1979 1980 1981 1982 1983 1984 1985
		 *
		 * 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
1986
		 */
1987 1988
		if (!(sig->flags & SIGNAL_STOP_STOPPED))
			sig->group_exit_code = signr;
L
Linus Torvalds 已提交
1989

1990 1991 1992 1993
		sig->group_stop_count = 0;

		if (task_set_jobctl_pending(current, signr | gstop))
			sig->group_stop_count++;
L
Linus Torvalds 已提交
1994

1995 1996
		t = current;
		while_each_thread(current, t) {
L
Linus Torvalds 已提交
1997
			/*
1998 1999 2000
			 * 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
2001
			 */
2002 2003
			if (!task_is_stopped(t) &&
			    task_set_jobctl_pending(t, signr | gstop)) {
2004
				sig->group_stop_count++;
2005 2006 2007 2008
				if (likely(!(t->ptrace & PT_SEIZED)))
					signal_wake_up(t, 0);
				else
					ptrace_trap_notify(t);
2009
			}
2010
		}
L
Linus Torvalds 已提交
2011
	}
2012

T
Tejun Heo 已提交
2013
	if (likely(!current->ptrace)) {
2014
		int notify = 0;
L
Linus Torvalds 已提交
2015

2016 2017 2018 2019 2020 2021 2022 2023
		/*
		 * 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;

2024
		__set_current_state(TASK_STOPPED);
2025 2026
		spin_unlock_irq(&current->sighand->siglock);

2027 2028 2029 2030 2031 2032 2033 2034 2035
		/*
		 * 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.
		 */
2036 2037
		if (notify) {
			read_lock(&tasklist_lock);
2038
			do_notify_parent_cldstop(current, false, notify);
2039 2040 2041 2042
			read_unlock(&tasklist_lock);
		}

		/* Now we don't run again until woken by SIGCONT or SIGKILL */
2043
		freezable_schedule();
2044
		return true;
2045
	} else {
2046 2047 2048 2049 2050 2051
		/*
		 * 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;
2052
	}
2053
}
L
Linus Torvalds 已提交
2054

2055 2056 2057
/**
 * do_jobctl_trap - take care of ptrace jobctl traps
 *
T
Tejun Heo 已提交
2058 2059 2060 2061 2062 2063 2064
 * 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.
2065 2066 2067 2068 2069 2070 2071
 *
 * 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
2072
	struct signal_struct *signal = current->signal;
2073
	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
2074

T
Tejun Heo 已提交
2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085
	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;
2086
	}
L
Linus Torvalds 已提交
2087 2088
}

2089
static int ptrace_signal(int signr, siginfo_t *info)
R
Roland McGrath 已提交
2090
{
2091
	ptrace_signal_deliver();
2092 2093 2094 2095 2096 2097 2098 2099 2100 2101
	/*
	 * 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
2102
	ptrace_stop(signr, CLD_TRAPPED, 0, info);
R
Roland McGrath 已提交
2103 2104 2105 2106 2107 2108 2109 2110

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

	current->exit_code = 0;

2111 2112 2113 2114 2115 2116
	/*
	 * 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
2117 2118 2119 2120
	if (signr != info->si_signo) {
		info->si_signo = signr;
		info->si_errno = 0;
		info->si_code = SI_USER;
2121
		rcu_read_lock();
R
Roland McGrath 已提交
2122
		info->si_pid = task_pid_vnr(current->parent);
2123 2124
		info->si_uid = from_kuid_munged(current_user_ns(),
						task_uid(current->parent));
2125
		rcu_read_unlock();
R
Roland McGrath 已提交
2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136
	}

	/* 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;
}

2137
int get_signal(struct ksignal *ksig)
L
Linus Torvalds 已提交
2138
{
2139 2140 2141
	struct sighand_struct *sighand = current->sighand;
	struct signal_struct *signal = current->signal;
	int signr;
L
Linus Torvalds 已提交
2142

2143 2144
	if (unlikely(current->task_works))
		task_work_run();
2145

2146 2147 2148
	if (unlikely(uprobe_deny_signal()))
		return 0;

R
Roland McGrath 已提交
2149
	/*
2150 2151 2152
	 * Do this once, we can't return to user-mode if freezing() == T.
	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
	 * thus do not need another check after return.
R
Roland McGrath 已提交
2153
	 */
2154 2155
	try_to_freeze();

2156
relock:
2157
	spin_lock_irq(&sighand->siglock);
2158 2159 2160 2161 2162
	/*
	 * 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.
	 */
2163
	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
2164 2165 2166 2167 2168 2169 2170
		int why;

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

2171
		signal->flags &= ~SIGNAL_CLD_MASK;
2172

2173
		spin_unlock_irq(&sighand->siglock);
R
Roland McGrath 已提交
2174

2175 2176 2177 2178 2179 2180 2181 2182
		/*
		 * 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
2183
		read_lock(&tasklist_lock);
2184 2185
		do_notify_parent_cldstop(current, false, why);

2186 2187 2188
		if (ptrace_reparented(current->group_leader))
			do_notify_parent_cldstop(current->group_leader,
						true, why);
T
Tejun Heo 已提交
2189
		read_unlock(&tasklist_lock);
2190

2191 2192 2193
		goto relock;
	}

L
Linus Torvalds 已提交
2194 2195
	for (;;) {
		struct k_sigaction *ka;
2196

T
Tejun Heo 已提交
2197 2198
		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
		    do_signal_stop(0))
2199
			goto relock;
2200

2201 2202 2203 2204 2205
		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
			do_jobctl_trap();
			spin_unlock_irq(&sighand->siglock);
			goto relock;
		}
L
Linus Torvalds 已提交
2206

2207
		signr = dequeue_signal(current, &current->blocked, &ksig->info);
2208

T
Tejun Heo 已提交
2209 2210
		if (!signr)
			break; /* will return 0 */
2211

2212
		if (unlikely(current->ptrace) && signr != SIGKILL) {
2213
			signr = ptrace_signal(signr, &ksig->info);
T
Tejun Heo 已提交
2214 2215
			if (!signr)
				continue;
L
Linus Torvalds 已提交
2216 2217
		}

T
Tejun Heo 已提交
2218 2219
		ka = &sighand->action[signr-1];

2220
		/* Trace actually delivered signals. */
2221
		trace_signal_deliver(signr, &ksig->info, ka);
2222

L
Linus Torvalds 已提交
2223 2224 2225 2226
		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
			continue;
		if (ka->sa.sa_handler != SIG_DFL) {
			/* Run the handler.  */
2227
			ksig->ka = *ka;
L
Linus Torvalds 已提交
2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240

			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;

2241
		/*
2242
		 * Global init gets no signals it doesn't want.
2243 2244 2245 2246 2247 2248 2249
		 * 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.
2250
		 */
2251
		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
2252
				!sig_kernel_only(signr))
L
Linus Torvalds 已提交
2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266
			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) {
2267
				spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2268 2269 2270

				/* signals can be posted during this window */

2271
				if (is_current_pgrp_orphaned())
L
Linus Torvalds 已提交
2272 2273
					goto relock;

2274
				spin_lock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2275 2276
			}

2277
			if (likely(do_signal_stop(ksig->info.si_signo))) {
L
Linus Torvalds 已提交
2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288
				/* It released the siglock.  */
				goto relock;
			}

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

2289
		spin_unlock_irq(&sighand->siglock);
L
Linus Torvalds 已提交
2290 2291 2292 2293 2294

		/*
		 * Anything else is fatal, maybe with a core dump.
		 */
		current->flags |= PF_SIGNALED;
2295

L
Linus Torvalds 已提交
2296
		if (sig_kernel_coredump(signr)) {
2297
			if (print_fatal_signals)
2298
				print_fatal_signal(ksig->info.si_signo);
2299
			proc_coredump_connector(current);
L
Linus Torvalds 已提交
2300 2301 2302 2303 2304 2305 2306 2307
			/*
			 * 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.
			 */
2308
			do_coredump(&ksig->info);
L
Linus Torvalds 已提交
2309 2310 2311 2312 2313
		}

		/*
		 * Death signals, no core dump.
		 */
2314
		do_group_exit(ksig->info.si_signo);
L
Linus Torvalds 已提交
2315 2316
		/* NOTREACHED */
	}
2317
	spin_unlock_irq(&sighand->siglock);
2318 2319 2320

	ksig->sig = signr;
	return ksig->sig > 0;
L
Linus Torvalds 已提交
2321 2322
}

2323
/**
A
Al Viro 已提交
2324
 * signal_delivered - 
R
Richard Weinberger 已提交
2325
 * @ksig:		kernel signal struct
A
Al Viro 已提交
2326
 * @stepping:		nonzero if debugger single-step or block-step in use
2327
 *
2328
 * This function should be called when a signal has successfully been
R
Richard Weinberger 已提交
2329
 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
A
Al Viro 已提交
2330
 * is always blocked, and the signal itself is blocked unless %SA_NODEFER
R
Richard Weinberger 已提交
2331
 * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
2332
 */
R
Richard Weinberger 已提交
2333
static void signal_delivered(struct ksignal *ksig, int stepping)
2334 2335 2336
{
	sigset_t blocked;

2337 2338 2339 2340 2341 2342
	/* A signal was successfully delivered, and the
	   saved sigmask was stored on the signal frame,
	   and will be restored by sigreturn.  So we can
	   simply clear the restore sigmask flag.  */
	clear_restore_sigmask();

R
Richard Weinberger 已提交
2343 2344 2345
	sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
	if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
		sigaddset(&blocked, ksig->sig);
2346
	set_current_blocked(&blocked);
2347
	tracehook_signal_handler(stepping);
2348 2349
}

A
Al Viro 已提交
2350 2351 2352 2353 2354
void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
{
	if (failed)
		force_sigsegv(ksig->sig, current);
	else
R
Richard Weinberger 已提交
2355
		signal_delivered(ksig, stepping);
A
Al Viro 已提交
2356 2357
}

2358 2359
/*
 * It could be that complete_signal() picked us to notify about the
2360 2361
 * group-wide signal. Other threads should be notified now to take
 * the shared signals in @which since we will not.
2362
 */
2363
static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
2364
{
2365
	sigset_t retarget;
2366 2367
	struct task_struct *t;

2368 2369 2370 2371
	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
	if (sigisemptyset(&retarget))
		return;

2372 2373
	t = tsk;
	while_each_thread(tsk, t) {
2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386
		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;
2387 2388 2389
	}
}

O
Oleg Nesterov 已提交
2390 2391 2392
void exit_signals(struct task_struct *tsk)
{
	int group_stop = 0;
2393
	sigset_t unblocked;
O
Oleg Nesterov 已提交
2394

2395 2396 2397 2398
	/*
	 * @tsk is about to have PF_EXITING set - lock out users which
	 * expect stable threadgroup.
	 */
2399
	cgroup_threadgroup_change_begin(tsk);
2400

2401 2402
	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
		tsk->flags |= PF_EXITING;
2403
		cgroup_threadgroup_change_end(tsk);
2404
		return;
O
Oleg Nesterov 已提交
2405 2406
	}

2407
	spin_lock_irq(&tsk->sighand->siglock);
O
Oleg Nesterov 已提交
2408 2409 2410 2411 2412
	/*
	 * From now this task is not visible for group-wide signals,
	 * see wants_signal(), do_signal_stop().
	 */
	tsk->flags |= PF_EXITING;
2413

2414
	cgroup_threadgroup_change_end(tsk);
2415

2416 2417 2418
	if (!signal_pending(tsk))
		goto out;

2419 2420 2421
	unblocked = tsk->blocked;
	signotset(&unblocked);
	retarget_shared_pending(tsk, &unblocked);
2422

2423
	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
2424
	    task_participate_group_stop(tsk))
T
Tejun Heo 已提交
2425
		group_stop = CLD_STOPPED;
2426
out:
O
Oleg Nesterov 已提交
2427 2428
	spin_unlock_irq(&tsk->sighand->siglock);

2429 2430 2431 2432
	/*
	 * If group stop has completed, deliver the notification.  This
	 * should always go to the real parent of the group leader.
	 */
2433
	if (unlikely(group_stop)) {
O
Oleg Nesterov 已提交
2434
		read_lock(&tasklist_lock);
2435
		do_notify_parent_cldstop(tsk, false, group_stop);
O
Oleg Nesterov 已提交
2436 2437 2438 2439
		read_unlock(&tasklist_lock);
	}
}

L
Linus Torvalds 已提交
2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451
EXPORT_SYMBOL(recalc_sigpending);
EXPORT_SYMBOL_GPL(dequeue_signal);
EXPORT_SYMBOL(flush_signals);
EXPORT_SYMBOL(force_sig);
EXPORT_SYMBOL(send_sig);
EXPORT_SYMBOL(send_sig_info);
EXPORT_SYMBOL(sigprocmask);

/*
 * System call entry points.
 */

2452 2453 2454
/**
 *  sys_restart_syscall - restart a system call
 */
2455
SYSCALL_DEFINE0(restart_syscall)
L
Linus Torvalds 已提交
2456
{
2457
	struct restart_block *restart = &current->restart_block;
L
Linus Torvalds 已提交
2458 2459 2460 2461 2462 2463 2464 2465
	return restart->fn(restart);
}

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

2466 2467 2468 2469 2470
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. */
2471
		sigandnsets(&newblocked, newset, &current->blocked);
2472 2473 2474 2475 2476 2477
		retarget_shared_pending(tsk, &newblocked);
	}
	tsk->blocked = *newset;
	recalc_sigpending();
}

2478 2479 2480 2481 2482 2483
/**
 * 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
2484
 */
2485 2486 2487
void set_current_blocked(sigset_t *newset)
{
	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
2488
	__set_current_blocked(newset);
2489 2490 2491
}

void __set_current_blocked(const sigset_t *newset)
2492 2493 2494
{
	struct task_struct *tsk = current;

2495 2496 2497 2498 2499 2500 2501
	/*
	 * In case the signal mask hasn't changed, there is nothing we need
	 * to do. The current->blocked shouldn't be modified by other task.
	 */
	if (sigequalsets(&tsk->blocked, newset))
		return;

2502
	spin_lock_irq(&tsk->sighand->siglock);
2503
	__set_task_blocked(tsk, newset);
2504 2505
	spin_unlock_irq(&tsk->sighand->siglock);
}
L
Linus Torvalds 已提交
2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516

/*
 * 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)
{
2517 2518
	struct task_struct *tsk = current;
	sigset_t newset;
L
Linus Torvalds 已提交
2519

2520
	/* Lockless, only current can change ->blocked, never from irq */
2521
	if (oldset)
2522
		*oldset = tsk->blocked;
2523

L
Linus Torvalds 已提交
2524 2525
	switch (how) {
	case SIG_BLOCK:
2526
		sigorsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2527 2528
		break;
	case SIG_UNBLOCK:
2529
		sigandnsets(&newset, &tsk->blocked, set);
L
Linus Torvalds 已提交
2530 2531
		break;
	case SIG_SETMASK:
2532
		newset = *set;
L
Linus Torvalds 已提交
2533 2534
		break;
	default:
2535
		return -EINVAL;
L
Linus Torvalds 已提交
2536
	}
2537

2538
	__set_current_blocked(&newset);
2539
	return 0;
L
Linus Torvalds 已提交
2540 2541
}

2542 2543 2544
/**
 *  sys_rt_sigprocmask - change the list of currently blocked signals
 *  @how: whether to add, remove, or set signals
R
Randy Dunlap 已提交
2545
 *  @nset: stores pending signals
2546 2547 2548
 *  @oset: previous value of signal mask if non-null
 *  @sigsetsize: size of sigset_t type
 */
2549
SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
2550
		sigset_t __user *, oset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2551 2552
{
	sigset_t old_set, new_set;
2553
	int error;
L
Linus Torvalds 已提交
2554 2555 2556

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
2557
		return -EINVAL;
L
Linus Torvalds 已提交
2558

2559 2560 2561 2562 2563
	old_set = current->blocked;

	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2564 2565
		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

2566
		error = sigprocmask(how, &new_set, NULL);
L
Linus Torvalds 已提交
2567
		if (error)
2568 2569
			return error;
	}
L
Linus Torvalds 已提交
2570

2571 2572 2573
	if (oset) {
		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
			return -EFAULT;
L
Linus Torvalds 已提交
2574
	}
2575 2576

	return 0;
L
Linus Torvalds 已提交
2577 2578
}

A
Al Viro 已提交
2579 2580 2581
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
		compat_sigset_t __user *, oset, compat_size_t, sigsetsize)
L
Linus Torvalds 已提交
2582
{
A
Al Viro 已提交
2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606
#ifdef __BIG_ENDIAN
	sigset_t old_set = current->blocked;

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

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

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

		error = sigprocmask(how, &new_set, NULL);
		if (error)
			return error;
	}
	if (oset) {
		compat_sigset_t old32;
		sigset_to_compat(&old32, &old_set);
A
Al Viro 已提交
2607
		if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
A
Al Viro 已提交
2608 2609 2610 2611 2612 2613 2614 2615 2616
			return -EFAULT;
	}
	return 0;
#else
	return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
				  (sigset_t __user *)oset, sigsetsize);
#endif
}
#endif
L
Linus Torvalds 已提交
2617

A
Al Viro 已提交
2618
static int do_sigpending(void *set, unsigned long sigsetsize)
L
Linus Torvalds 已提交
2619 2620
{
	if (sigsetsize > sizeof(sigset_t))
A
Al Viro 已提交
2621
		return -EINVAL;
L
Linus Torvalds 已提交
2622 2623

	spin_lock_irq(&current->sighand->siglock);
A
Al Viro 已提交
2624
	sigorsets(set, &current->pending.signal,
L
Linus Torvalds 已提交
2625 2626 2627 2628
		  &current->signal->shared_pending.signal);
	spin_unlock_irq(&current->sighand->siglock);

	/* Outside the lock because only this thread touches it.  */
A
Al Viro 已提交
2629 2630
	sigandsets(set, &current->blocked, set);
	return 0;
2631
}
L
Linus Torvalds 已提交
2632

2633 2634 2635
/**
 *  sys_rt_sigpending - examine a pending signal that has been raised
 *			while blocked
2636
 *  @uset: stores pending signals
2637 2638
 *  @sigsetsize: size of sigset_t type or larger
 */
A
Al Viro 已提交
2639
SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
L
Linus Torvalds 已提交
2640
{
A
Al Viro 已提交
2641 2642 2643 2644 2645 2646 2647 2648 2649 2650
	sigset_t set;
	int err = do_sigpending(&set, sigsetsize);
	if (!err && copy_to_user(uset, &set, sigsetsize))
		err = -EFAULT;
	return err;
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
		compat_size_t, sigsetsize)
L
Linus Torvalds 已提交
2651
{
A
Al Viro 已提交
2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665
#ifdef __BIG_ENDIAN
	sigset_t set;
	int err = do_sigpending(&set, sigsetsize);
	if (!err) {
		compat_sigset_t set32;
		sigset_to_compat(&set32, &set);
		/* we can get here only if sigsetsize <= sizeof(set) */
		if (copy_to_user(uset, &set32, sigsetsize))
			err = -EFAULT;
	}
	return err;
#else
	return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
#endif
L
Linus Torvalds 已提交
2666
}
A
Al Viro 已提交
2667
#endif
L
Linus Torvalds 已提交
2668 2669 2670

#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER

A
Al Viro 已提交
2671
int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
L
Linus Torvalds 已提交
2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682
{
	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.
2683 2684
	 * Please remember to update the signalfd_copyinfo() function
	 * inside fs/signalfd.c too, in case siginfo_t changes.
L
Linus Torvalds 已提交
2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709
	 * 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
2710 2711
#endif
#ifdef BUS_MCEERR_AO
2712
		/*
A
Andi Kleen 已提交
2713
		 * Other callers might not initialize the si_lsb field,
2714
		 * so check explicitly for the right codes here.
A
Andi Kleen 已提交
2715
		 */
2716 2717
		if (from->si_signo == SIGBUS &&
		    (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
A
Andi Kleen 已提交
2718
			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
2719 2720
#endif
#ifdef SEGV_BNDERR
2721 2722 2723 2724
		if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
			err |= __put_user(from->si_lower, &to->si_lower);
			err |= __put_user(from->si_upper, &to->si_upper);
		}
2725 2726 2727 2728
#endif
#ifdef SEGV_PKUERR
		if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
			err |= __put_user(from->si_pkey, &to->si_pkey);
L
Linus Torvalds 已提交
2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743
#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;
2744 2745 2746 2747 2748 2749 2750
#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
2751 2752 2753 2754 2755 2756 2757 2758 2759 2760
	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

2761 2762 2763 2764 2765 2766 2767
/**
 *  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,
2768
		    const struct timespec *ts)
2769
{
T
Thomas Gleixner 已提交
2770
	ktime_t *to = NULL, timeout = KTIME_MAX;
2771 2772
	struct task_struct *tsk = current;
	sigset_t mask = *which;
2773
	int sig, ret = 0;
2774 2775 2776 2777

	if (ts) {
		if (!timespec_valid(ts))
			return -EINVAL;
2778 2779
		timeout = timespec_to_ktime(*ts);
		to = &timeout;
2780 2781 2782 2783 2784 2785 2786 2787 2788 2789
	}

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

	spin_lock_irq(&tsk->sighand->siglock);
	sig = dequeue_signal(tsk, &mask, info);
T
Thomas Gleixner 已提交
2790
	if (!sig && timeout) {
2791 2792 2793
		/*
		 * None ready, temporarily unblock those we're interested
		 * while we are sleeping in so that we'll be awakened when
2794 2795
		 * they arrive. Unblocking is always fine, we can avoid
		 * set_current_blocked().
2796 2797 2798 2799 2800 2801
		 */
		tsk->real_blocked = tsk->blocked;
		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
		recalc_sigpending();
		spin_unlock_irq(&tsk->sighand->siglock);

2802 2803 2804
		__set_current_state(TASK_INTERRUPTIBLE);
		ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns,
							 HRTIMER_MODE_REL);
2805
		spin_lock_irq(&tsk->sighand->siglock);
2806
		__set_task_blocked(tsk, &tsk->real_blocked);
2807
		sigemptyset(&tsk->real_blocked);
2808
		sig = dequeue_signal(tsk, &mask, info);
2809 2810 2811 2812 2813
	}
	spin_unlock_irq(&tsk->sighand->siglock);

	if (sig)
		return sig;
2814
	return ret ? -EINTR : -EAGAIN;
2815 2816
}

2817 2818 2819 2820 2821 2822 2823 2824
/**
 *  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
 */
2825 2826 2827
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
2828 2829 2830 2831
{
	sigset_t these;
	struct timespec ts;
	siginfo_t info;
2832
	int ret;
L
Linus Torvalds 已提交
2833 2834 2835 2836 2837 2838 2839

	/* 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;
2840

L
Linus Torvalds 已提交
2841 2842 2843 2844 2845
	if (uts) {
		if (copy_from_user(&ts, uts, sizeof(ts)))
			return -EFAULT;
	}

2846
	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
L
Linus Torvalds 已提交
2847

2848 2849 2850
	if (ret > 0 && uinfo) {
		if (copy_siginfo_to_user(uinfo, &info))
			ret = -EFAULT;
L
Linus Torvalds 已提交
2851 2852 2853 2854 2855
	}

	return ret;
}

2856 2857 2858 2859 2860
/**
 *  sys_kill - send a signal to a process
 *  @pid: the PID of the process
 *  @sig: signal to be sent
 */
2861
SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2862 2863 2864 2865 2866 2867
{
	struct siginfo info;

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_USER;
2868
	info.si_pid = task_tgid_vnr(current);
2869
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
L
Linus Torvalds 已提交
2870 2871 2872 2873

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

T
Thomas Gleixner 已提交
2874 2875
static int
do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
L
Linus Torvalds 已提交
2876 2877
{
	struct task_struct *p;
T
Thomas Gleixner 已提交
2878
	int error = -ESRCH;
L
Linus Torvalds 已提交
2879

2880
	rcu_read_lock();
2881
	p = find_task_by_vpid(pid);
2882
	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
T
Thomas Gleixner 已提交
2883
		error = check_kill_permission(sig, info, p);
L
Linus Torvalds 已提交
2884 2885 2886 2887
		/*
		 * The null signal is a permissions and process existence
		 * probe.  No signal is actually delivered.
		 */
2888 2889 2890 2891 2892 2893 2894 2895 2896
		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
2897 2898
		}
	}
2899
	rcu_read_unlock();
2900

L
Linus Torvalds 已提交
2901 2902 2903
	return error;
}

T
Thomas Gleixner 已提交
2904 2905
static int do_tkill(pid_t tgid, pid_t pid, int sig)
{
2906
	struct siginfo info = {};
T
Thomas Gleixner 已提交
2907 2908 2909 2910 2911

	info.si_signo = sig;
	info.si_errno = 0;
	info.si_code = SI_TKILL;
	info.si_pid = task_tgid_vnr(current);
2912
	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
T
Thomas Gleixner 已提交
2913 2914 2915 2916

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

2917 2918 2919 2920 2921 2922
/**
 *  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
 *
2923
 *  This syscall also checks the @tgid and returns -ESRCH even if the PID
2924 2925 2926
 *  exists but it's not belonging to the target process anymore. This
 *  method solves the problem of threads exiting and PIDs getting reused.
 */
2927
SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
2928 2929 2930 2931 2932 2933 2934 2935
{
	/* This is only valid for single tasks */
	if (pid <= 0 || tgid <= 0)
		return -EINVAL;

	return do_tkill(tgid, pid, sig);
}

2936 2937 2938 2939 2940
/**
 *  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
2941 2942
 *  Send a signal to only one task, even if it's a CLONE_THREAD task.
 */
2943
SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
L
Linus Torvalds 已提交
2944 2945 2946 2947 2948
{
	/* This is only valid for single tasks */
	if (pid <= 0)
		return -EINVAL;

2949
	return do_tkill(0, pid, sig);
L
Linus Torvalds 已提交
2950 2951
}

A
Al Viro 已提交
2952 2953 2954 2955 2956
static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
{
	/* Not even root can pretend to send signals from the kernel.
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
2957
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
2958
	    (task_pid_vnr(current) != pid))
A
Al Viro 已提交
2959
		return -EPERM;
2960

A
Al Viro 已提交
2961 2962 2963 2964 2965 2966
	info->si_signo = sig;

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

2967 2968 2969 2970 2971 2972
/**
 *  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
 */
2973 2974
SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
		siginfo_t __user *, uinfo)
L
Linus Torvalds 已提交
2975 2976 2977 2978
{
	siginfo_t info;
	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
		return -EFAULT;
A
Al Viro 已提交
2979 2980
	return do_rt_sigqueueinfo(pid, sig, &info);
}
L
Linus Torvalds 已提交
2981

A
Al Viro 已提交
2982 2983 2984 2985 2986 2987
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
2988
	siginfo_t info = {};
A
Al Viro 已提交
2989 2990 2991 2992
	int ret = copy_siginfo_from_user32(&info, uinfo);
	if (unlikely(ret))
		return ret;
	return do_rt_sigqueueinfo(pid, sig, &info);
L
Linus Torvalds 已提交
2993
}
A
Al Viro 已提交
2994
#endif
L
Linus Torvalds 已提交
2995

2996
static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
2997 2998 2999 3000 3001 3002
{
	/* 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.
3003 3004
	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
	 */
3005 3006
	if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
	    (task_pid_vnr(current) != pid))
3007
		return -EPERM;
3008

3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024
	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);
}

3025 3026 3027 3028 3029 3030 3031
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo,
			compat_pid_t, tgid,
			compat_pid_t, pid,
			int, sig,
			struct compat_siginfo __user *, uinfo)
{
3032
	siginfo_t info = {};
3033 3034 3035 3036 3037 3038 3039

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

3040
/*
3041
 * For kthreads only, must not be used if cloned with CLONE_SIGHAND
3042
 */
3043
void kernel_sigaction(int sig, __sighandler_t action)
3044
{
3045
	spin_lock_irq(&current->sighand->siglock);
3046 3047 3048
	current->sighand->action[sig - 1].sa.sa_handler = action;
	if (action == SIG_IGN) {
		sigset_t mask;
3049

3050 3051
		sigemptyset(&mask);
		sigaddset(&mask, sig);
3052

3053 3054 3055 3056
		flush_sigqueue_mask(&mask, &current->signal->shared_pending);
		flush_sigqueue_mask(&mask, &current->pending);
		recalc_sigpending();
	}
3057 3058
	spin_unlock_irq(&current->sighand->siglock);
}
3059
EXPORT_SYMBOL(kernel_sigaction);
3060

3061 3062 3063 3064 3065
void __weak sigaction_compat_abi(struct k_sigaction *act,
		struct k_sigaction *oact)
{
}

3066
int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
L
Linus Torvalds 已提交
3067
{
3068
	struct task_struct *p = current, *t;
L
Linus Torvalds 已提交
3069
	struct k_sigaction *k;
3070
	sigset_t mask;
L
Linus Torvalds 已提交
3071

3072
	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
L
Linus Torvalds 已提交
3073 3074
		return -EINVAL;

3075
	k = &p->sighand->action[sig-1];
L
Linus Torvalds 已提交
3076

3077
	spin_lock_irq(&p->sighand->siglock);
L
Linus Torvalds 已提交
3078 3079 3080
	if (oact)
		*oact = *k;

3081 3082
	sigaction_compat_abi(act, oact);

L
Linus Torvalds 已提交
3083
	if (act) {
3084 3085
		sigdelsetmask(&act->sa.sa_mask,
			      sigmask(SIGKILL) | sigmask(SIGSTOP));
3086
		*k = *act;
L
Linus Torvalds 已提交
3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097
		/*
		 * 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"
		 */
3098
		if (sig_handler_ignored(sig_handler(p, sig), sig)) {
3099 3100
			sigemptyset(&mask);
			sigaddset(&mask, sig);
3101 3102
			flush_sigqueue_mask(&mask, &p->signal->shared_pending);
			for_each_thread(p, t)
3103
				flush_sigqueue_mask(&mask, &t->pending);
L
Linus Torvalds 已提交
3104 3105 3106
		}
	}

3107
	spin_unlock_irq(&p->sighand->siglock);
L
Linus Torvalds 已提交
3108 3109 3110
	return 0;
}

3111
static int
L
Linus Torvalds 已提交
3112 3113 3114 3115 3116
do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
{
	stack_t oss;
	int error;

3117 3118
	oss.ss_sp = (void __user *) current->sas_ss_sp;
	oss.ss_size = current->sas_ss_size;
3119 3120
	oss.ss_flags = sas_ss_flags(sp) |
		(current->sas_ss_flags & SS_FLAG_BITS);
L
Linus Torvalds 已提交
3121 3122 3123 3124

	if (uss) {
		void __user *ss_sp;
		size_t ss_size;
3125 3126
		unsigned ss_flags;
		int ss_mode;
L
Linus Torvalds 已提交
3127 3128

		error = -EFAULT;
L
Linus Torvalds 已提交
3129 3130 3131 3132 3133 3134
		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
3135 3136 3137 3138 3139 3140
			goto out;

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

3141
		ss_mode = ss_flags & ~SS_FLAG_BITS;
L
Linus Torvalds 已提交
3142
		error = -EINVAL;
3143 3144
		if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
				ss_mode != 0)
L
Linus Torvalds 已提交
3145 3146
			goto out;

3147
		if (ss_mode == SS_DISABLE) {
L
Linus Torvalds 已提交
3148 3149 3150 3151 3152 3153 3154 3155 3156 3157
			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;
3158
		current->sas_ss_flags = ss_flags;
L
Linus Torvalds 已提交
3159 3160
	}

3161
	error = 0;
L
Linus Torvalds 已提交
3162 3163
	if (uoss) {
		error = -EFAULT;
3164
		if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
L
Linus Torvalds 已提交
3165
			goto out;
3166 3167 3168
		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
3169 3170 3171 3172 3173
	}

out:
	return error;
}
3174 3175 3176 3177
SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
{
	return do_sigaltstack(uss, uoss, current_user_stack_pointer());
}
L
Linus Torvalds 已提交
3178

A
Al Viro 已提交
3179 3180 3181 3182 3183 3184 3185
int restore_altstack(const stack_t __user *uss)
{
	int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
	/* squash all but EFAULT for now */
	return err == -EFAULT ? err : 0;
}

3186 3187 3188
int __save_altstack(stack_t __user *uss, unsigned long sp)
{
	struct task_struct *t = current;
3189 3190
	int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3191
		__put_user(t->sas_ss_size, &uss->ss_size);
3192 3193 3194 3195 3196
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3197 3198
}

A
Al Viro 已提交
3199
#ifdef CONFIG_COMPAT
3200 3201 3202
COMPAT_SYSCALL_DEFINE2(sigaltstack,
			const compat_stack_t __user *, uss_ptr,
			compat_stack_t __user *, uoss_ptr)
A
Al Viro 已提交
3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239
{
	stack_t uss, uoss;
	int ret;
	mm_segment_t seg;

	if (uss_ptr) {
		compat_stack_t uss32;

		memset(&uss, 0, sizeof(stack_t));
		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
			return -EFAULT;
		uss.ss_sp = compat_ptr(uss32.ss_sp);
		uss.ss_flags = uss32.ss_flags;
		uss.ss_size = uss32.ss_size;
	}
	seg = get_fs();
	set_fs(KERNEL_DS);
	ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
			     (stack_t __force __user *) &uoss,
			     compat_user_stack_pointer());
	set_fs(seg);
	if (ret >= 0 && uoss_ptr)  {
		if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
		    __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
		    __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
		    __put_user(uoss.ss_size, &uoss_ptr->ss_size))
			ret = -EFAULT;
	}
	return ret;
}

int compat_restore_altstack(const compat_stack_t __user *uss)
{
	int err = compat_sys_sigaltstack(uss, NULL);
	/* squash all but -EFAULT for now */
	return err == -EFAULT ? err : 0;
}
3240 3241 3242

int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
{
3243
	int err;
3244
	struct task_struct *t = current;
3245 3246 3247
	err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp),
			 &uss->ss_sp) |
		__put_user(t->sas_ss_flags, &uss->ss_flags) |
3248
		__put_user(t->sas_ss_size, &uss->ss_size);
3249 3250 3251 3252 3253
	if (err)
		return err;
	if (t->sas_ss_flags & SS_AUTODISARM)
		sas_ss_reset(t);
	return 0;
3254
}
A
Al Viro 已提交
3255
#endif
L
Linus Torvalds 已提交
3256 3257 3258

#ifdef __ARCH_WANT_SYS_SIGPENDING

3259 3260 3261 3262
/**
 *  sys_sigpending - examine pending signals
 *  @set: where mask of pending signal is returned
 */
3263
SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
L
Linus Torvalds 已提交
3264
{
A
Al Viro 已提交
3265
	return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 
L
Linus Torvalds 已提交
3266 3267 3268 3269 3270
}

#endif

#ifdef __ARCH_WANT_SYS_SIGPROCMASK
3271 3272 3273
/**
 *  sys_sigprocmask - examine and change blocked signals
 *  @how: whether to add, remove, or set signals
3274
 *  @nset: signals to add or remove (if non-null)
3275 3276
 *  @oset: previous value of signal mask if non-null
 *
3277 3278 3279
 * Some platforms have their own version with special arguments;
 * others support only sys_rt_sigprocmask.
 */
L
Linus Torvalds 已提交
3280

3281
SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
3282
		old_sigset_t __user *, oset)
L
Linus Torvalds 已提交
3283 3284
{
	old_sigset_t old_set, new_set;
3285
	sigset_t new_blocked;
L
Linus Torvalds 已提交
3286

3287
	old_set = current->blocked.sig[0];
L
Linus Torvalds 已提交
3288

3289 3290 3291
	if (nset) {
		if (copy_from_user(&new_set, nset, sizeof(*nset)))
			return -EFAULT;
L
Linus Torvalds 已提交
3292

3293
		new_blocked = current->blocked;
L
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3294 3295 3296

		switch (how) {
		case SIG_BLOCK:
3297
			sigaddsetmask(&new_blocked, new_set);
L
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3298 3299
			break;
		case SIG_UNBLOCK:
3300
			sigdelsetmask(&new_blocked, new_set);
L
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3301 3302
			break;
		case SIG_SETMASK:
3303
			new_blocked.sig[0] = new_set;
L
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3304
			break;
3305 3306
		default:
			return -EINVAL;
L
Linus Torvalds 已提交
3307 3308
		}

3309
		set_current_blocked(&new_blocked);
3310 3311 3312
	}

	if (oset) {
L
Linus Torvalds 已提交
3313
		if (copy_to_user(oset, &old_set, sizeof(*oset)))
3314
			return -EFAULT;
L
Linus Torvalds 已提交
3315
	}
3316 3317

	return 0;
L
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3318 3319 3320
}
#endif /* __ARCH_WANT_SYS_SIGPROCMASK */

3321
#ifndef CONFIG_ODD_RT_SIGACTION
3322 3323 3324
/**
 *  sys_rt_sigaction - alter an action taken by a process
 *  @sig: signal to be sent
3325 3326
 *  @act: new sigaction
 *  @oact: used to save the previous sigaction
3327 3328
 *  @sigsetsize: size of sigset_t type
 */
3329 3330 3331 3332
SYSCALL_DEFINE4(rt_sigaction, int, sig,
		const struct sigaction __user *, act,
		struct sigaction __user *, oact,
		size_t, sigsetsize)
L
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3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354
{
	struct k_sigaction new_sa, old_sa;
	int ret = -EINVAL;

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

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

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

	if (!ret && oact) {
		if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
			return -EFAULT;
	}
out:
	return ret;
}
A
Al Viro 已提交
3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
		const struct compat_sigaction __user *, act,
		struct compat_sigaction __user *, oact,
		compat_size_t, sigsetsize)
{
	struct k_sigaction new_ka, old_ka;
	compat_sigset_t mask;
#ifdef __ARCH_HAS_SA_RESTORER
	compat_uptr_t restorer;
#endif
	int ret;

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

	if (act) {
		compat_uptr_t handler;
		ret = get_user(handler, &act->sa_handler);
		new_ka.sa.sa_handler = compat_ptr(handler);
#ifdef __ARCH_HAS_SA_RESTORER
		ret |= get_user(restorer, &act->sa_restorer);
		new_ka.sa.sa_restorer = compat_ptr(restorer);
#endif
		ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask));
3381
		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
A
Al Viro 已提交
3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392
		if (ret)
			return -EFAULT;
		sigset_from_compat(&new_ka.sa.sa_mask, &mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
	if (!ret && oact) {
		sigset_to_compat(&mask, &old_ka.sa.sa_mask);
		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
			       &oact->sa_handler);
		ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
3393
		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
A
Al Viro 已提交
3394 3395 3396 3397 3398 3399 3400 3401
#ifdef __ARCH_HAS_SA_RESTORER
		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),
				&oact->sa_restorer);
#endif
	}
	return ret;
}
#endif
3402
#endif /* !CONFIG_ODD_RT_SIGACTION */
L
Linus Torvalds 已提交
3403

3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453 3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476 3477 3478 3479 3480
#ifdef CONFIG_OLD_SIGACTION
SYSCALL_DEFINE3(sigaction, int, sig,
		const struct old_sigaction __user *, act,
	        struct old_sigaction __user *, oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

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

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

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

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

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

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

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

	if (!ret && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(ptr_to_compat(old_ka.sa.sa_handler),
			       &oact->sa_handler) ||
		    __put_user(ptr_to_compat(old_ka.sa.sa_restorer),
			       &oact->sa_restorer) ||
		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
			return -EFAULT;
	}
	return ret;
}
#endif
L
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3481

3482
#ifdef CONFIG_SGETMASK_SYSCALL
L
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3483 3484 3485 3486

/*
 * For backwards compatibility.  Functionality superseded by sigprocmask.
 */
3487
SYSCALL_DEFINE0(sgetmask)
L
Linus Torvalds 已提交
3488 3489 3490 3491 3492
{
	/* SMP safe */
	return current->blocked.sig[0];
}

3493
SYSCALL_DEFINE1(ssetmask, int, newmask)
L
Linus Torvalds 已提交
3494
{
3495 3496
	int old = current->blocked.sig[0];
	sigset_t newset;
L
Linus Torvalds 已提交
3497

3498
	siginitset(&newset, newmask);
3499
	set_current_blocked(&newset);
L
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3500 3501 3502

	return old;
}
3503
#endif /* CONFIG_SGETMASK_SYSCALL */
L
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3504 3505 3506 3507 3508

#ifdef __ARCH_WANT_SYS_SIGNAL
/*
 * For backwards compatibility.  Functionality superseded by sigaction.
 */
3509
SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
L
Linus Torvalds 已提交
3510 3511 3512 3513 3514 3515
{
	struct k_sigaction new_sa, old_sa;
	int ret;

	new_sa.sa.sa_handler = handler;
	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
3516
	sigemptyset(&new_sa.sa.sa_mask);
L
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3517 3518 3519 3520 3521 3522 3523 3524 3525

	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

3526
SYSCALL_DEFINE0(pause)
L
Linus Torvalds 已提交
3527
{
3528
	while (!signal_pending(current)) {
3529
		__set_current_state(TASK_INTERRUPTIBLE);
3530 3531
		schedule();
	}
L
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3532 3533 3534 3535 3536
	return -ERESTARTNOHAND;
}

#endif

3537
static int sigsuspend(sigset_t *set)
A
Al Viro 已提交
3538 3539 3540 3541
{
	current->saved_sigmask = current->blocked;
	set_current_blocked(set);

3542 3543 3544 3545
	while (!signal_pending(current)) {
		__set_current_state(TASK_INTERRUPTIBLE);
		schedule();
	}
A
Al Viro 已提交
3546 3547 3548 3549
	set_restore_sigmask();
	return -ERESTARTNOHAND;
}

3550 3551 3552 3553 3554 3555
/**
 *  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
 */
3556
SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
3557 3558 3559 3560 3561 3562 3563 3564 3565
{
	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
3566
	return sigsuspend(&newset);
3567
}
A
Al Viro 已提交
3568 3569 3570 3571 3572 3573 3574 3575 3576 3577 3578 3579 3580 3581 3582 3583 3584 3585 3586 3587 3588 3589
 
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize)
{
#ifdef __BIG_ENDIAN
	sigset_t newset;
	compat_sigset_t newset32;

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

	if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t)))
		return -EFAULT;
	sigset_from_compat(&newset, &newset32);
	return sigsuspend(&newset);
#else
	/* on little-endian bitmaps don't care about granularity */
	return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize);
#endif
}
#endif
3590

3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606
#ifdef CONFIG_OLD_SIGSUSPEND
SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
{
	sigset_t blocked;
	siginitset(&blocked, mask);
	return sigsuspend(&blocked);
}
#endif
#ifdef CONFIG_OLD_SIGSUSPEND3
SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
{
	sigset_t blocked;
	siginitset(&blocked, mask);
	return sigsuspend(&blocked);
}
#endif
3607

3608
__weak const char *arch_vma_name(struct vm_area_struct *vma)
3609 3610 3611 3612
{
	return NULL;
}

L
Linus Torvalds 已提交
3613 3614
void __init signals_init(void)
{
3615 3616 3617 3618
	/* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */
	BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE
		!= offsetof(struct siginfo, _sifields._pad));

3619
	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
L
Linus Torvalds 已提交
3620
}
3621 3622 3623 3624 3625 3626 3627 3628 3629 3630 3631 3632 3633 3634 3635 3636 3637 3638 3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660

#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 */