1 /* IP tables module for matching the value of the IPv4 and TCP ECN bits
3 * ipt_ecn.c,v 1.3 2002/05/29 15:09:00 laforge Exp
5 * (C) 2002 by Harald Welte <laforge@gnumonks.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/tcp.h>
18 #include <linux/netfilter/x_tables.h>
19 #include <linux/netfilter_ipv4/ip_tables.h>
20 #include <linux/netfilter_ipv4/ipt_ecn.h>
22 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
23 MODULE_DESCRIPTION("iptables ECN matching module");
24 MODULE_LICENSE("GPL");
26 static inline int match_ip(const struct sk_buff *skb,
27 const struct ipt_ecn_info *einfo)
29 return ((skb->nh.iph->tos&IPT_ECN_IP_MASK) == einfo->ip_ect);
32 static inline int match_tcp(const struct sk_buff *skb,
33 const struct ipt_ecn_info *einfo,
36 struct tcphdr _tcph, *th;
38 /* In practice, TCP match does this, so can't fail. But let's
41 th = skb_header_pointer(skb, skb->nh.iph->ihl * 4,
42 sizeof(_tcph), &_tcph);
48 if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
49 if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
58 if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
59 if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
71 static int match(const struct sk_buff *skb,
72 const struct net_device *in, const struct net_device *out,
73 const struct xt_match *match, const void *matchinfo,
74 int offset, unsigned int protoff, int *hotdrop)
76 const struct ipt_ecn_info *info = matchinfo;
78 if (info->operation & IPT_ECN_OP_MATCH_IP)
79 if (!match_ip(skb, info))
82 if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
83 if (skb->nh.iph->protocol != IPPROTO_TCP)
85 if (!match_tcp(skb, info, hotdrop))
92 static int checkentry(const char *tablename, const void *ip_void,
93 const struct xt_match *match,
94 void *matchinfo, unsigned int hook_mask)
96 const struct ipt_ecn_info *info = matchinfo;
97 const struct ipt_ip *ip = ip_void;
99 if (info->operation & IPT_ECN_OP_MATCH_MASK)
102 if (info->invert & IPT_ECN_OP_MATCH_MASK)
105 if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)
106 && ip->proto != IPPROTO_TCP) {
107 printk(KERN_WARNING "ipt_ecn: can't match TCP bits in rule for"
108 " non-tcp packets\n");
115 static struct xt_match ecn_match = {
119 .matchsize = sizeof(struct ipt_ecn_info),
120 .checkentry = checkentry,
124 static int __init ipt_ecn_init(void)
126 return xt_register_match(&ecn_match);
129 static void __exit ipt_ecn_fini(void)
131 xt_unregister_match(&ecn_match);
134 module_init(ipt_ecn_init);
135 module_exit(ipt_ecn_fini);