net/netfilter/xt_conntrack.c - linux - Git at Google

 /*
  *	xt_conntrack - Netfilter module to match connection tracking
  *	information. (Superset of Rusty's minimalistic state match.)
  *
  *	(C) 2001  Marc Boucher (marc@mbsi.ca).
  *	Copyright © CC Computer Consultants GmbH, 2007 - 2008
  *
  *	This program is free software; you can redistribute it and/or modify
  *	it under the terms of the GNU General Public License version 2 as
  *	published by the Free Software Foundation.
  */

 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <net/ipv6.h>
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter/xt_conntrack.h>
 #include <net/netfilter/nf_conntrack.h>

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
 MODULE_DESCRIPTION("Xtables: connection tracking state match");
 MODULE_ALIAS("ipt_conntrack");
 MODULE_ALIAS("ip6t_conntrack");

 static bool
 conntrack_addrcmp(const union nf_inet_addr *kaddr,
                   const union nf_inet_addr *uaddr,
                   const union nf_inet_addr *umask, unsigned int l3proto)
 {
 	if (l3proto == NFPROTO_IPV4)
 		return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
 	else if (l3proto == NFPROTO_IPV6)
 		return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
 		       &uaddr->in6) == 0;
 	else
 		return false;
 }

 static inline bool
 conntrack_mt_origsrc(const struct nf_conn *ct,
                      const struct xt_conntrack_mtinfo2 *info,
 		     u_int8_t family)
 {
 	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
 	       &info->origsrc_addr, &info->origsrc_mask, family);
 }

 static inline bool
 conntrack_mt_origdst(const struct nf_conn *ct,
                      const struct xt_conntrack_mtinfo2 *info,
 		     u_int8_t family)
 {
 	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
 	       &info->origdst_addr, &info->origdst_mask, family);
 }

 static inline bool
 conntrack_mt_replsrc(const struct nf_conn *ct,
                      const struct xt_conntrack_mtinfo2 *info,
 		     u_int8_t family)
 {
 	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
 	       &info->replsrc_addr, &info->replsrc_mask, family);
 }

 static inline bool
 conntrack_mt_repldst(const struct nf_conn *ct,
                      const struct xt_conntrack_mtinfo2 *info,
 		     u_int8_t family)
 {
 	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
 	       &info->repldst_addr, &info->repldst_mask, family);
 }

 static inline bool
 ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
                     const struct nf_conn *ct)
 {
 	const struct nf_conntrack_tuple *tuple;

 	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 	if ((info->match_flags & XT_CONNTRACK_PROTO) &&
 	    (nf_ct_protonum(ct) == info->l4proto) ^
 	    !(info->invert_flags & XT_CONNTRACK_PROTO))
 		return false;

 	/* Shortcut to match all recognized protocols by using ->src.all. */
 	if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
 	    (tuple->src.u.all == info->origsrc_port) ^
 	    !(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
 		return false;

 	if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
 	    (tuple->dst.u.all == info->origdst_port) ^
 	    !(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
 		return false;

 	tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;

 	if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
 	    (tuple->src.u.all == info->replsrc_port) ^
 	    !(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
 		return false;

 	if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
 	    (tuple->dst.u.all == info->repldst_port) ^
 	    !(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
 		return false;

 	return true;
 }

 static bool
 conntrack_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 {
 	const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
 	enum ip_conntrack_info ctinfo;
 	const struct nf_conn *ct;
 	unsigned int statebit;

 	ct = nf_ct_get(skb, &ctinfo);

 	if (ct == &nf_conntrack_untracked)
 		statebit = XT_CONNTRACK_STATE_UNTRACKED;
 	else if (ct != NULL)
 		statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
 	else
 		statebit = XT_CONNTRACK_STATE_INVALID;

 	if (info->match_flags & XT_CONNTRACK_STATE) {
 		if (ct != NULL) {
 			if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
 				statebit |= XT_CONNTRACK_STATE_SNAT;
 			if (test_bit(IPS_DST_NAT_BIT, &ct->status))
 				statebit |= XT_CONNTRACK_STATE_DNAT;
 		}
 		if (!!(info->state_mask & statebit) ^
 		    !(info->invert_flags & XT_CONNTRACK_STATE))
 			return false;
 	}

 	if (ct == NULL)
 		return info->match_flags & XT_CONNTRACK_STATE;
 	if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
 	    (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
 	    !!(info->invert_flags & XT_CONNTRACK_DIRECTION))
 		return false;

 	if (info->match_flags & XT_CONNTRACK_ORIGSRC)
 		if (conntrack_mt_origsrc(ct, info, par->family) ^
 		    !(info->invert_flags & XT_CONNTRACK_ORIGSRC))
 			return false;

 	if (info->match_flags & XT_CONNTRACK_ORIGDST)
 		if (conntrack_mt_origdst(ct, info, par->family) ^
 		    !(info->invert_flags & XT_CONNTRACK_ORIGDST))
 			return false;

 	if (info->match_flags & XT_CONNTRACK_REPLSRC)
 		if (conntrack_mt_replsrc(ct, info, par->family) ^
 		    !(info->invert_flags & XT_CONNTRACK_REPLSRC))
 			return false;

 	if (info->match_flags & XT_CONNTRACK_REPLDST)
 		if (conntrack_mt_repldst(ct, info, par->family) ^
 		    !(info->invert_flags & XT_CONNTRACK_REPLDST))
 			return false;

 	if (!ct_proto_port_check(info, ct))
 		return false;

 	if ((info->match_flags & XT_CONNTRACK_STATUS) &&
 	    (!!(info->status_mask & ct->status) ^
 	    !(info->invert_flags & XT_CONNTRACK_STATUS)))
 		return false;

 	if (info->match_flags & XT_CONNTRACK_EXPIRES) {
 		unsigned long expires = 0;

 		if (timer_pending(&ct->timeout))
 			expires = (ct->timeout.expires - jiffies) / HZ;
 		if ((expires >= info->expires_min &&
 		    expires <= info->expires_max) ^
 		    !(info->invert_flags & XT_CONNTRACK_EXPIRES))
 			return false;
 	}
 	return true;
 }

 static bool
 conntrack_mt_v1(const struct sk_buff *skb, const struct xt_match_param *par)
 {
 	const struct xt_conntrack_mtinfo2 *const *info = par->matchinfo;
 	struct xt_match_param newpar = *par;

 	newpar.matchinfo = *info;
 	return conntrack_mt(skb, &newpar);
 }

 static bool conntrack_mt_check(const struct xt_mtchk_param *par)
 {
 	if (nf_ct_l3proto_try_module_get(par->family) < 0) {
 		printk(KERN_WARNING "can't load conntrack support for "
 				    "proto=%u\n", par->family);
 		return false;
 	}
 	return true;
 }

 static bool conntrack_mt_check_v1(const struct xt_mtchk_param *par)
 {
 	struct xt_conntrack_mtinfo1 *info = par->matchinfo;
 	struct xt_conntrack_mtinfo2 *up;
 	int ret = conntrack_mt_check(par);

 	if (ret < 0)
 		return ret;

 	up = kmalloc(sizeof(*up), GFP_KERNEL);
 	if (up == NULL) {
 		nf_ct_l3proto_module_put(par->family);
 		return -ENOMEM;
 	}

 	/*
 	 * The strategy here is to minimize the overhead of v1 matching,
 	 * by prebuilding a v2 struct and putting the pointer into the
 	 * v1 dataspace.
 	 */
 	memcpy(up, info, offsetof(typeof(*info), state_mask));
 	up->state_mask  = info->state_mask;
 	up->status_mask = info->status_mask;
 	*(void **)info  = up;
 	return true;
 }

 static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
 {
 	nf_ct_l3proto_module_put(par->family);
 }

 static void conntrack_mt_destroy_v1(const struct xt_mtdtor_param *par)
 {
 	struct xt_conntrack_mtinfo2 **info = par->matchinfo;
 	kfree(*info);
 	conntrack_mt_destroy(par);
 }

 static struct xt_match conntrack_mt_reg[] __read_mostly = {
 	{
 		.name       = "conntrack",
 		.revision   = 1,
 		.family     = NFPROTO_UNSPEC,
 		.matchsize  = sizeof(struct xt_conntrack_mtinfo1),
 		.match      = conntrack_mt_v1,
 		.checkentry = conntrack_mt_check_v1,
 		.destroy    = conntrack_mt_destroy_v1,
 		.me         = THIS_MODULE,
 	},
 	{
 		.name       = "conntrack",
 		.revision   = 2,
 		.family     = NFPROTO_UNSPEC,
 		.matchsize  = sizeof(struct xt_conntrack_mtinfo2),
 		.match      = conntrack_mt,
 		.checkentry = conntrack_mt_check,
 		.destroy    = conntrack_mt_destroy,
 		.me         = THIS_MODULE,
 	},
 };

 static int __init conntrack_mt_init(void)
 {
 	return xt_register_matches(conntrack_mt_reg,
 	       ARRAY_SIZE(conntrack_mt_reg));
 }

 static void __exit conntrack_mt_exit(void)
 {
 	xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
 }

 module_init(conntrack_mt_init);
 module_exit(conntrack_mt_exit);
	/*
	* xt_conntrack - Netfilter module to match connection tracking
	* information. (Superset of Rusty's minimalistic state match.)
	*
	* (C) 2001 Marc Boucher (marc@mbsi.ca).
	* Copyright © CC Computer Consultants GmbH, 2007 - 2008
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/module.h>
	#include <linux/skbuff.h>
	#include <net/ipv6.h>
	#include <linux/netfilter/x_tables.h>
	#include <linux/netfilter/xt_conntrack.h>
	#include <net/netfilter/nf_conntrack.h>

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
	MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
	MODULE_DESCRIPTION("Xtables: connection tracking state match");
	MODULE_ALIAS("ipt_conntrack");
	MODULE_ALIAS("ip6t_conntrack");

	static bool
	conntrack_addrcmp(const union nf_inet_addr *kaddr,
	const union nf_inet_addr *uaddr,
	const union nf_inet_addr *umask, unsigned int l3proto)
	{
	if (l3proto == NFPROTO_IPV4)
	return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
	else if (l3proto == NFPROTO_IPV6)
	return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
	&uaddr->in6) == 0;
	else
	return false;
	}

	static inline bool
	conntrack_mt_origsrc(const struct nf_conn *ct,
	const struct xt_conntrack_mtinfo2 *info,
	u_int8_t family)
	{
	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
	&info->origsrc_addr, &info->origsrc_mask, family);
	}

	static inline bool
	conntrack_mt_origdst(const struct nf_conn *ct,
	const struct xt_conntrack_mtinfo2 *info,
	u_int8_t family)
	{
	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
	&info->origdst_addr, &info->origdst_mask, family);
	}

	static inline bool
	conntrack_mt_replsrc(const struct nf_conn *ct,
	const struct xt_conntrack_mtinfo2 *info,
	u_int8_t family)
	{
	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
	&info->replsrc_addr, &info->replsrc_mask, family);
	}

	static inline bool
	conntrack_mt_repldst(const struct nf_conn *ct,
	const struct xt_conntrack_mtinfo2 *info,
	u_int8_t family)
	{
	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
	&info->repldst_addr, &info->repldst_mask, family);
	}

	static inline bool
	ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
	const struct nf_conn *ct)
	{
	const struct nf_conntrack_tuple *tuple;

	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
	if ((info->match_flags & XT_CONNTRACK_PROTO) &&
	(nf_ct_protonum(ct) == info->l4proto) ^
	!(info->invert_flags & XT_CONNTRACK_PROTO))
	return false;

	/* Shortcut to match all recognized protocols by using ->src.all. */
	if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
	(tuple->src.u.all == info->origsrc_port) ^
	!(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
	return false;

	if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
	(tuple->dst.u.all == info->origdst_port) ^
	!(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
	return false;

	tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;

	if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
	(tuple->src.u.all == info->replsrc_port) ^
	!(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
	return false;

	if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
	(tuple->dst.u.all == info->repldst_port) ^
	!(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
	return false;

	return true;
	}

	static bool
	conntrack_mt(const struct sk_buff skb, const struct xt_match_param par)
	{
	const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
	enum ip_conntrack_info ctinfo;
	const struct nf_conn *ct;
	unsigned int statebit;

	ct = nf_ct_get(skb, &ctinfo);

	if (ct == &nf_conntrack_untracked)
	statebit = XT_CONNTRACK_STATE_UNTRACKED;
	else if (ct != NULL)
	statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
	else
	statebit = XT_CONNTRACK_STATE_INVALID;

	if (info->match_flags & XT_CONNTRACK_STATE) {
	if (ct != NULL) {
	if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
	statebit \|= XT_CONNTRACK_STATE_SNAT;
	if (test_bit(IPS_DST_NAT_BIT, &ct->status))
	statebit \|= XT_CONNTRACK_STATE_DNAT;
	}
	if (!!(info->state_mask & statebit) ^
	!(info->invert_flags & XT_CONNTRACK_STATE))
	return false;
	}

	if (ct == NULL)
	return info->match_flags & XT_CONNTRACK_STATE;
	if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
	(CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
	!!(info->invert_flags & XT_CONNTRACK_DIRECTION))
	return false;

	if (info->match_flags & XT_CONNTRACK_ORIGSRC)
	if (conntrack_mt_origsrc(ct, info, par->family) ^
	!(info->invert_flags & XT_CONNTRACK_ORIGSRC))
	return false;

	if (info->match_flags & XT_CONNTRACK_ORIGDST)
	if (conntrack_mt_origdst(ct, info, par->family) ^
	!(info->invert_flags & XT_CONNTRACK_ORIGDST))
	return false;

	if (info->match_flags & XT_CONNTRACK_REPLSRC)
	if (conntrack_mt_replsrc(ct, info, par->family) ^
	!(info->invert_flags & XT_CONNTRACK_REPLSRC))
	return false;

	if (info->match_flags & XT_CONNTRACK_REPLDST)
	if (conntrack_mt_repldst(ct, info, par->family) ^
	!(info->invert_flags & XT_CONNTRACK_REPLDST))
	return false;

	if (!ct_proto_port_check(info, ct))
	return false;

	if ((info->match_flags & XT_CONNTRACK_STATUS) &&
	(!!(info->status_mask & ct->status) ^
	!(info->invert_flags & XT_CONNTRACK_STATUS)))
	return false;

	if (info->match_flags & XT_CONNTRACK_EXPIRES) {
	unsigned long expires = 0;

	if (timer_pending(&ct->timeout))
	expires = (ct->timeout.expires - jiffies) / HZ;
	if ((expires >= info->expires_min &&
	expires <= info->expires_max) ^
	!(info->invert_flags & XT_CONNTRACK_EXPIRES))
	return false;
	}
	return true;
	}

	static bool
	conntrack_mt_v1(const struct sk_buff skb, const struct xt_match_param par)
	{
	const struct xt_conntrack_mtinfo2 const info = par->matchinfo;
	struct xt_match_param newpar = *par;

	newpar.matchinfo = *info;
	return conntrack_mt(skb, &newpar);
	}

	static bool conntrack_mt_check(const struct xt_mtchk_param *par)
	{
	if (nf_ct_l3proto_try_module_get(par->family) < 0) {
	printk(KERN_WARNING "can't load conntrack support for "
	"proto=%u\n", par->family);
	return false;
	}
	return true;
	}

	static bool conntrack_mt_check_v1(const struct xt_mtchk_param *par)
	{
	struct xt_conntrack_mtinfo1 *info = par->matchinfo;
	struct xt_conntrack_mtinfo2 *up;
	int ret = conntrack_mt_check(par);

	if (ret < 0)
	return ret;

	up = kmalloc(sizeof(*up), GFP_KERNEL);
	if (up == NULL) {
	nf_ct_l3proto_module_put(par->family);
	return -ENOMEM;
	}

	/*
	* The strategy here is to minimize the overhead of v1 matching,
	* by prebuilding a v2 struct and putting the pointer into the
	* v1 dataspace.
	*/
	memcpy(up, info, offsetof(typeof(*info), state_mask));
	up->state_mask = info->state_mask;
	up->status_mask = info->status_mask;
	(void *)info = up;
	return true;
	}

	static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
	{
	nf_ct_l3proto_module_put(par->family);
	}

	static void conntrack_mt_destroy_v1(const struct xt_mtdtor_param *par)
	{
	struct xt_conntrack_mtinfo2 **info = par->matchinfo;
	kfree(*info);
	conntrack_mt_destroy(par);
	}

	static struct xt_match conntrack_mt_reg[] __read_mostly = {
	{
	.name = "conntrack",
	.revision = 1,
	.family = NFPROTO_UNSPEC,
	.matchsize = sizeof(struct xt_conntrack_mtinfo1),
	.match = conntrack_mt_v1,
	.checkentry = conntrack_mt_check_v1,
	.destroy = conntrack_mt_destroy_v1,
	.me = THIS_MODULE,
	},
	{
	.name = "conntrack",
	.revision = 2,
	.family = NFPROTO_UNSPEC,
	.matchsize = sizeof(struct xt_conntrack_mtinfo2),
	.match = conntrack_mt,
	.checkentry = conntrack_mt_check,
	.destroy = conntrack_mt_destroy,
	.me = THIS_MODULE,
	},
	};

	static int __init conntrack_mt_init(void)
	{
	return xt_register_matches(conntrack_mt_reg,
	ARRAY_SIZE(conntrack_mt_reg));
	}

	static void __exit conntrack_mt_exit(void)
	{
	xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
	}

	module_init(conntrack_mt_init);
	module_exit(conntrack_mt_exit);