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Commit af0d29cd authored by Patrick McHardy's avatar Patrick McHardy Committed by Pablo Neira Ayuso
Browse files

netfilter: xtables: add an IPv6 capable version of the ECN match 

References: http://www.spinics.net/lists/netfilter-devel/msg18875.html



Augment xt_ecn by facilities to match on IPv6 packets' DSCP/TOS field
similar to how it is already done for the IPv4 packet field.

Signed-off-by: default avatarJan Engelhardt <jengelh@medozas.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent a4c6f9d3

net/netfilter/xt_ecn.c

+80 −26
Original line number Diff line number Diff line 
/* IP tables module for matching the value of the IPv4 and TCP ECN bits

/*

 * Xtables module for matching the value of the IPv4/IPv6 and TCP ECN bits

 *

 * (C) 2002 by Harald Welte <laforge@gnumonks.org>

 * (C) 2011 Patrick McHardy <kaber@trash.net>

 *

 * 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
@@ -17,32 +19,25 @@ 
#include <linux/netfilter/x_tables.h>

#include <linux/netfilter/xt_ecn.h>

#include <linux/netfilter_ipv4/ip_tables.h>

#include <linux/netfilter_ipv6/ip6_tables.h>



MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");

MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match for IPv4");

MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match");

MODULE_LICENSE("GPL");

MODULE_ALIAS("ipt_ecn");

MODULE_ALIAS("ip6t_ecn");



static inline bool match_ip(const struct sk_buff *skb,

			    const struct xt_ecn_info *einfo)

{

	return ((ip_hdr(skb)->tos & XT_ECN_IP_MASK) == einfo->ip_ect) ^

	       !!(einfo->invert & XT_ECN_OP_MATCH_IP);

}



static inline bool match_tcp(const struct sk_buff *skb,

			     const struct xt_ecn_info *einfo,

			     bool *hotdrop)

static bool match_tcp(const struct sk_buff *skb, struct xt_action_param *par)

{

	const struct xt_ecn_info *einfo = par->matchinfo;

	struct tcphdr _tcph;

	const struct tcphdr *th;



	/* In practice, TCP match does this, so can't fail.  But let's

	 * be good citizens.

	 */

	th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);

	th = skb_header_pointer(skb, par->thoff, sizeof(_tcph), &_tcph);

	if (th == NULL) {

		*hotdrop = false;

		return false;

	}
@@ -69,7 +64,14 @@ static inline bool match_tcp(const struct sk_buff *skb, 
	return true;

}



static bool ecn_mt(const struct sk_buff *skb, struct xt_action_param *par)

static inline bool match_ip(const struct sk_buff *skb,

			    const struct xt_ecn_info *einfo)

{

	return ((ip_hdr(skb)->tos & XT_ECN_IP_MASK) == einfo->ip_ect) ^

	       !!(einfo->invert & XT_ECN_OP_MATCH_IP);

}



static bool ecn_mt4(const struct sk_buff *skb, struct xt_action_param *par)

{

	const struct xt_ecn_info *info = par->matchinfo;
@@ -78,14 +80,14 @@ static bool ecn_mt(const struct sk_buff *skb, struct xt_action_param *par) 
			return false;



	if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR)) {

		if (!match_tcp(skb, info, &par->hotdrop))

		if (!match_tcp(skb, par))

			return false;

	}



	return true;

}



static int ecn_mt_check(const struct xt_mtchk_param *par)

static int ecn_mt_check4(const struct xt_mtchk_param *par)

{

	const struct xt_ecn_info *info = par->matchinfo;

	const struct ipt_ip *ip = par->entryinfo;
@@ -105,23 +107,75 @@ static int ecn_mt_check(const struct xt_mtchk_param *par) 
	return 0;

}



static struct xt_match ecn_mt_reg __read_mostly = {

static inline bool match_ipv6(const struct sk_buff *skb,

			      const struct xt_ecn_info *einfo)

{

	return (((ipv6_hdr(skb)->flow_lbl[0] >> 4) & XT_ECN_IP_MASK) ==

	        einfo->ip_ect) ^

	       !!(einfo->invert & XT_ECN_OP_MATCH_IP);

}



static bool ecn_mt6(const struct sk_buff *skb, struct xt_action_param *par)

{

	const struct xt_ecn_info *info = par->matchinfo;



	if (info->operation & XT_ECN_OP_MATCH_IP && !match_ipv6(skb, info))

		return false;



	if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) &&

	    !match_tcp(skb, par))

		return false;



	return true;

}



static int ecn_mt_check6(const struct xt_mtchk_param *par)

{

	const struct xt_ecn_info *info = par->matchinfo;

	const struct ip6t_ip6 *ip = par->entryinfo;



	if (info->operation & XT_ECN_OP_MATCH_MASK)

		return -EINVAL;



	if (info->invert & XT_ECN_OP_MATCH_MASK)

		return -EINVAL;



	if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) &&

	    (ip->proto != IPPROTO_TCP || ip->invflags & IP6T_INV_PROTO)) {

		pr_info("cannot match TCP bits in rule for non-tcp packets\n");

		return -EINVAL;

	}



	return 0;

}



static struct xt_match ecn_mt_reg[] __read_mostly = {

	{

		.name		= "ecn",

		.family		= NFPROTO_IPV4,

	.match		= ecn_mt,

		.match		= ecn_mt4,

		.matchsize	= sizeof(struct xt_ecn_info),

		.checkentry	= ecn_mt_check4,

		.me		= THIS_MODULE,

	},

	{

		.name		= "ecn",

		.family		= NFPROTO_IPV6,

		.match		= ecn_mt6,

		.matchsize	= sizeof(struct xt_ecn_info),

	.checkentry	= ecn_mt_check,

		.checkentry	= ecn_mt_check6,

		.me		= THIS_MODULE,

	},

};



static int __init ecn_mt_init(void)

{

	return xt_register_match(&ecn_mt_reg);

	return xt_register_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg));

}



static void __exit ecn_mt_exit(void)

{

	xt_unregister_match(&ecn_mt_reg);

	xt_unregister_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg));

}



module_init(ecn_mt_init);