netfilter: xtables: move ipt_ecn to xt_ecn

Prepare the ECN match for augmentation by an IPv6 counterpart. Since
no symbol dependencies to ipv6.ko are added, having a single ecn match
module is the more so welcome.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 5 insertions, 133 deletions

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 7e1f5cdaf11e..53b9c79c8025 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -76,11 +76,11 @@ config IP_NF_MATCH_AH
 config IP_NF_MATCH_ECN
 	tristate '"ecn" match support'
 	depends on NETFILTER_ADVANCED
-	help
-	  This option adds a `ECN' match, which allows you to match against
-	  the IPv4 and TCP header ECN fields.
-
-	  To compile it as a module, choose M here.  If unsure, say N.
+	select NETFILTER_XT_MATCH_ECN
+	---help---
+	This is a backwards-compat option for the user's convenience
+	(e.g. when running oldconfig). It selects
+	CONFIG_NETFILTER_XT_MATCH_ECN.
 
 config IP_NF_MATCH_RPFILTER
 	tristate '"rpfilter" reverse path filter match support'
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index 123dd88cea53..213a462b739b 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -49,7 +49,6 @@ obj-$(CONFIG_IP_NF_SECURITY) += iptable_security.o
 
 # matches
 obj-$(CONFIG_IP_NF_MATCH_AH) += ipt_ah.o
-obj-$(CONFIG_IP_NF_MATCH_ECN) += ipt_ecn.o
 obj-$(CONFIG_IP_NF_MATCH_RPFILTER) += ipt_rpfilter.o
 
 # targets
diff --git a/net/ipv4/netfilter/ipt_ecn.c b/net/ipv4/netfilter/ipt_ecn.c
deleted file mode 100644
index 2b57e52c746c..000000000000
--- a/net/ipv4/netfilter/ipt_ecn.c
+++ /dev/null
@@ -1,127 +0,0 @@
-/* IP tables module for matching the value of the IPv4 and TCP ECN bits
- *
- * (C) 2002 by Harald Welte <laforge@gnumonks.org>
- *
- * 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.
- */
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-#include <linux/in.h>
-#include <linux/ip.h>
-#include <net/ip.h>
-#include <linux/module.h>
-#include <linux/skbuff.h>
-#include <linux/tcp.h>
-
-#include <linux/netfilter/x_tables.h>
-#include <linux/netfilter_ipv4/ip_tables.h>
-#include <linux/netfilter_ipv4/ipt_ecn.h>
-
-MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
-MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match for IPv4");
-MODULE_LICENSE("GPL");
-
-static inline bool match_ip(const struct sk_buff *skb,
-			    const struct ipt_ecn_info *einfo)
-{
-	return ((ip_hdr(skb)->tos & IPT_ECN_IP_MASK) == einfo->ip_ect) ^
-	       !!(einfo->invert & IPT_ECN_OP_MATCH_IP);
-}
-
-static inline bool match_tcp(const struct sk_buff *skb,
-			     const struct ipt_ecn_info *einfo,
-			     bool *hotdrop)
-{
-	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);
-	if (th == NULL) {
-		*hotdrop = false;
-		return false;
-	}
-
-	if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
-		if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
-			if (th->ece == 1)
-				return false;
-		} else {
-			if (th->ece == 0)
-				return false;
-		}
-	}
-
-	if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
-		if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
-			if (th->cwr == 1)
-				return false;
-		} else {
-			if (th->cwr == 0)
-				return false;
-		}
-	}
-
-	return true;
-}
-
-static bool ecn_mt(const struct sk_buff *skb, struct xt_action_param *par)
-{
-	const struct ipt_ecn_info *info = par->matchinfo;
-
-	if (info->operation & IPT_ECN_OP_MATCH_IP)
-		if (!match_ip(skb, info))
-			return false;
-
-	if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
-		if (!match_tcp(skb, info, &par->hotdrop))
-			return false;
-	}
-
-	return true;
-}
-
-static int ecn_mt_check(const struct xt_mtchk_param *par)
-{
-	const struct ipt_ecn_info *info = par->matchinfo;
-	const struct ipt_ip *ip = par->entryinfo;
-
-	if (info->operation & IPT_ECN_OP_MATCH_MASK)
-		return -EINVAL;
-
-	if (info->invert & IPT_ECN_OP_MATCH_MASK)
-		return -EINVAL;
-
-	if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR) &&
-	    (ip->proto != IPPROTO_TCP || ip->invflags & IPT_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,
-	.matchsize	= sizeof(struct ipt_ecn_info),
-	.checkentry	= ecn_mt_check,
-	.me		= THIS_MODULE,
-};
-
-static int __init ecn_mt_init(void)
-{
-	return xt_register_match(&ecn_mt_reg);
-}
-
-static void __exit ecn_mt_exit(void)
-{
-	xt_unregister_match(&ecn_mt_reg);
-}
-
-module_init(ecn_mt_init);
-module_exit(ecn_mt_exit);