1 /* IP tables module for matching the value of the IPv4 and TCP ECN bits
3 * (C) 2002 by Harald Welte <laforge@gnumonks.org>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/tcp.h>
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter_ipv4/ip_tables.h>
19 #include <linux/netfilter_ipv4/ipt_ecn.h>
21 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
22 MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match for IPv4");
23 MODULE_LICENSE("GPL");
25 static inline bool match_ip(const struct sk_buff *skb,
26 const struct ipt_ecn_info *einfo)
28 return (ip_hdr(skb)->tos & IPT_ECN_IP_MASK) == einfo->ip_ect;
31 static inline bool match_tcp(const struct sk_buff *skb,
32 const struct ipt_ecn_info *einfo,
36 const struct tcphdr *th;
38 /* In practice, TCP match does this, so can't fail. But let's
41 th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
47 if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
48 if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
57 if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
58 if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
70 static bool ecn_mt(const struct sk_buff *skb, struct xt_action_param *par)
72 const struct ipt_ecn_info *info = par->matchinfo;
74 if (info->operation & IPT_ECN_OP_MATCH_IP)
75 if (!match_ip(skb, info))
78 if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
79 if (!match_tcp(skb, info, &par->hotdrop))
86 static int ecn_mt_check(const struct xt_mtchk_param *par)
88 const struct ipt_ecn_info *info = par->matchinfo;
89 const struct ipt_ip *ip = par->entryinfo;
91 if (info->operation & IPT_ECN_OP_MATCH_MASK)
94 if (info->invert & IPT_ECN_OP_MATCH_MASK)
97 if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR) &&
98 (ip->proto != IPPROTO_TCP || ip->invflags & IPT_INV_PROTO)) {
99 pr_info("cannot match TCP bits in rule for non-tcp packets\n");
106 static struct xt_match ecn_mt_reg __read_mostly = {
108 .family = NFPROTO_IPV4,
110 .matchsize = sizeof(struct ipt_ecn_info),
111 .checkentry = ecn_mt_check,
115 static int __init ecn_mt_init(void)
117 return xt_register_match(&ecn_mt_reg);
120 static void __exit ecn_mt_exit(void)
122 xt_unregister_match(&ecn_mt_reg);
125 module_init(ecn_mt_init);
126 module_exit(ecn_mt_exit);