Serialize pfil hooks' adding/removing by netisr0

[dragonfly.git] / sys / net / pfil.c

/*	$NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $	*/
/* $DragonFly: src/sys/net/pfil.c,v 1.10 2008/09/14 08:58:55 sephe Exp $ */

/*
 * Copyright (c) 1996 Matthew R. Green
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/queue.h>

#include <net/if.h>
#include <net/pfil.h>
#include <net/netmsg2.h>

#define PFIL_CFGPORT	cpu_portfn(0)

struct netmsg_pfil {
	struct netmsg		pfil_nmsg;
	pfil_func_t		pfil_func;
	void			*pfil_arg;
	int			pfil_flags;
	struct pfil_head	*pfil_ph;
};

static int pfil_list_add(struct pfil_head *, pfil_func_t, void *, int);
static int pfil_list_remove(struct pfil_head *, pfil_func_t, void *, int);

LIST_HEAD(, pfil_head) pfil_head_list =
    LIST_HEAD_INITIALIZER(&pfil_head_list);

/*
 * pfil_run_hooks() runs the specified packet filter hooks.
 */
int
pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
    int dir)
{
	struct packet_filter_hook *pfh;
	struct mbuf *m = *mp;
	pfil_list_t *list;
	int rv = 0;

	if (dir == PFIL_IN)
		list = &ph->ph_in;
	else if (dir == PFIL_OUT)
		list = &ph->ph_out;
	else
		return 0; /* XXX panic? */

	TAILQ_FOREACH(pfh, list, pfil_link) {
		if (pfh->pfil_func != NULL) {
			rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir);
			if (rv != 0 || m == NULL)
				break;
		}
	}

	*mp = m;
	return (rv);
}

/*
 * pfil_head_register() registers a pfil_head with the packet filter
 * hook mechanism.
 */
int
pfil_head_register(struct pfil_head *ph)
{
	struct pfil_head *lph;

	LIST_FOREACH(lph, &pfil_head_list, ph_list) {
		if (ph->ph_type == lph->ph_type &&
		    ph->ph_un.phu_val == lph->ph_un.phu_val)
			return EEXIST;
	}

	TAILQ_INIT(&ph->ph_in);
	TAILQ_INIT(&ph->ph_out);
	ph->ph_hashooks = 0;

	LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);

	return (0);
}

/*
 * pfil_head_unregister() removes a pfil_head from the packet filter
 * hook mechanism.
 */
int
pfil_head_unregister(struct pfil_head *pfh)
{
	LIST_REMOVE(pfh, ph_list);
	return (0);
}

/*
 * pfil_head_get() returns the pfil_head for a given key/dlt.
 */
struct pfil_head *
pfil_head_get(int type, u_long val)
{
	struct pfil_head *ph;

	LIST_FOREACH(ph, &pfil_head_list, ph_list) {
		if (ph->ph_type == type && ph->ph_un.phu_val == val)
			break;
	}
	return (ph);
}

static void
pfil_add_hook_dispatch(struct netmsg *nmsg)
{
	struct netmsg_pfil *pfilmsg = (struct netmsg_pfil *)nmsg;
	pfil_func_t func = pfilmsg->pfil_func;
	void *arg = pfilmsg->pfil_arg;
	int flags = pfilmsg->pfil_flags;
	struct pfil_head *ph = pfilmsg->pfil_ph;
	int err = 0;

	if (flags & PFIL_IN) {
		err = pfil_list_add(ph, func, arg, flags & ~PFIL_OUT);
		if (err)
			goto reply;
	}
	if (flags & PFIL_OUT) {
		err = pfil_list_add(ph, func, arg, flags & ~PFIL_IN);
		if (err) {
			if (flags & PFIL_IN)
				pfil_list_remove(ph, func, arg, PFIL_IN);
		}
	}
reply:
	lwkt_replymsg(&nmsg->nm_lmsg, err);
}

/*
 * pfil_add_hook() adds a function to the packet filter hook.  the
 * flags are:
 *	PFIL_IN		call me on incoming packets
 *	PFIL_OUT	call me on outgoing packets
 *	PFIL_ALL	call me on all of the above
 *	PFIL_WAITOK	OK to call kmalloc with M_WAITOK.
 */
int
pfil_add_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
{
	struct netmsg_pfil pfilmsg;
	struct netmsg *nmsg;

	nmsg = &pfilmsg.pfil_nmsg;
	netmsg_init(nmsg, &curthread->td_msgport, 0, pfil_add_hook_dispatch);
	pfilmsg.pfil_func = func;
	pfilmsg.pfil_arg = arg;
	pfilmsg.pfil_flags = flags;
	pfilmsg.pfil_ph = ph;

	return lwkt_domsg(PFIL_CFGPORT, &nmsg->nm_lmsg, 0);
}

static int
pfil_list_add(struct pfil_head *ph, pfil_func_t func, void *arg, int flags)
{
	struct packet_filter_hook *pfh;
	pfil_list_t *list;

	KKASSERT(&curthread->td_msgport == PFIL_CFGPORT);

	list = (flags & PFIL_IN) ? &ph->ph_in : &ph->ph_out;

	/*
	 * First make sure the hook is not already there.
	 */
	TAILQ_FOREACH(pfh, list, pfil_link) {
		if (pfh->pfil_func == func && pfh->pfil_arg == arg)
			return EEXIST;
	}

	pfh = (struct packet_filter_hook *)kmalloc(sizeof(*pfh), M_IFADDR,
	    (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
	if (pfh == NULL)
		return ENOMEM;

	pfh->pfil_func = func;
	pfh->pfil_arg  = arg;

	/*
	 * insert the input list in reverse order of the output list
	 * so that the same path is followed in or out of the kernel.
	 */
	if (flags & PFIL_IN)
		TAILQ_INSERT_HEAD(list, pfh, pfil_link);
	else
		TAILQ_INSERT_TAIL(list, pfh, pfil_link);
	ph->ph_hashooks = 1;
	return (0);
}

static void
pfil_remove_hook_dispatch(struct netmsg *nmsg)
{
	struct netmsg_pfil *pfilmsg = (struct netmsg_pfil *)nmsg;
	pfil_func_t func = pfilmsg->pfil_func;
	void *arg = pfilmsg->pfil_arg;
	int flags = pfilmsg->pfil_flags;
	struct pfil_head *ph = pfilmsg->pfil_ph;
	int err = 0;

	if (flags & PFIL_IN)
		err = pfil_list_remove(ph, func, arg, PFIL_IN);
	if ((err == 0) && (flags & PFIL_OUT))
		err = pfil_list_remove(ph, func, arg, PFIL_OUT);
	lwkt_replymsg(&nmsg->nm_lmsg, err);
}

/*
 * pfil_remove_hook removes a specific function from the packet filter
 * hook list.
 */
int
pfil_remove_hook(pfil_func_t func, void *arg, int flags, struct pfil_head *ph)
{
	struct netmsg_pfil pfilmsg;
	struct netmsg *nmsg;

	nmsg = &pfilmsg.pfil_nmsg;
	netmsg_init(nmsg, &curthread->td_msgport, 0, pfil_remove_hook_dispatch);
	pfilmsg.pfil_func = func;
	pfilmsg.pfil_arg = arg;
	pfilmsg.pfil_flags = flags;
	pfilmsg.pfil_ph = ph;

	return lwkt_domsg(PFIL_CFGPORT, &nmsg->nm_lmsg, 0);
}

/*
 * pfil_list_remove is an internal function that takes a function off the
 * specified list.  Clear ph_hashooks if no functions remain on any list.
 */
static int
pfil_list_remove(struct pfil_head *ph, pfil_func_t func, void *arg, int flags)
{
	struct packet_filter_hook *pfh;
	pfil_list_t *list;

	KKASSERT(&curthread->td_msgport == PFIL_CFGPORT);

	list = (flags & PFIL_IN) ? &ph->ph_in : &ph->ph_out;

	TAILQ_FOREACH(pfh, list, pfil_link) {
		if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
			TAILQ_REMOVE(list, pfh, pfil_link);
			kfree(pfh, M_IFADDR);
			if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out))
				ph->ph_hashooks = 0;
			return 0;
		}
	}
	return ENOENT;
}