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 int 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 int 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 int 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
, int *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
);