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.
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("iptables ECN matching module");
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,
35 struct tcphdr _tcph, *th;
37 /* In practice, TCP match does this, so can't fail. But let's
40 th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
46 if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
47 if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
56 if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
57 if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
69 static bool match(const struct sk_buff *skb,
70 const struct net_device *in, const struct net_device *out,
71 const struct xt_match *match, const void *matchinfo,
72 int offset, unsigned int protoff, bool *hotdrop)
74 const struct ipt_ecn_info *info = matchinfo;
76 if (info->operation & IPT_ECN_OP_MATCH_IP)
77 if (!match_ip(skb, info))
80 if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
81 if (ip_hdr(skb)->protocol != IPPROTO_TCP)
83 if (!match_tcp(skb, info, hotdrop))
90 static int checkentry(const char *tablename, const void *ip_void,
91 const struct xt_match *match,
92 void *matchinfo, unsigned int hook_mask)
94 const struct ipt_ecn_info *info = matchinfo;
95 const struct ipt_ip *ip = ip_void;
97 if (info->operation & IPT_ECN_OP_MATCH_MASK)
100 if (info->invert & IPT_ECN_OP_MATCH_MASK)
103 if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)
104 && ip->proto != IPPROTO_TCP) {
105 printk(KERN_WARNING "ipt_ecn: can't match TCP bits in rule for"
106 " non-tcp packets\n");
113 static struct xt_match ecn_match = {
117 .matchsize = sizeof(struct ipt_ecn_info),
118 .checkentry = checkentry,
122 static int __init ipt_ecn_init(void)
124 return xt_register_match(&ecn_match);
127 static void __exit ipt_ecn_fini(void)
129 xt_unregister_match(&ecn_match);
132 module_init(ipt_ecn_init);
133 module_exit(ipt_ecn_fini);