[NETFILTER]: Update modules' descriptions
[deliverable/linux.git] / net / ipv4 / netfilter / ipt_ECN.c
CommitLineData
1da177e4
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1/* iptables module for the IPv4 and TCP ECN bits, Version 1.5
2 *
3 * (C) 2002 by Harald Welte <laforge@netfilter.org>
e905a9ed 4 *
1da177e4 5 * This program is free software; you can redistribute it and/or modify
e905a9ed 6 * it under the terms of the GNU General Public License version 2 as
1da177e4 7 * published by the Free Software Foundation.
1da177e4
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8*/
9
6709dbbb 10#include <linux/in.h>
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11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <linux/ip.h>
c9bdd4b5 14#include <net/ip.h>
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15#include <linux/tcp.h>
16#include <net/checksum.h>
17
6709dbbb 18#include <linux/netfilter/x_tables.h>
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19#include <linux/netfilter_ipv4/ip_tables.h>
20#include <linux/netfilter_ipv4/ipt_ECN.h>
21
22MODULE_LICENSE("GPL");
23MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
2ae15b64 24MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag modification");
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25
26/* set ECT codepoint from IP header.
e1931b78
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27 * return false if there was an error. */
28static inline bool
3db05fea 29set_ect_ip(struct sk_buff *skb, const struct ipt_ECN_info *einfo)
1da177e4 30{
3db05fea 31 struct iphdr *iph = ip_hdr(skb);
1da177e4 32
da878c8e 33 if ((iph->tos & IPT_ECN_IP_MASK) != (einfo->ip_ect & IPT_ECN_IP_MASK)) {
43bc0ca7 34 __u8 oldtos;
3db05fea 35 if (!skb_make_writable(skb, sizeof(struct iphdr)))
e1931b78 36 return false;
3db05fea 37 iph = ip_hdr(skb);
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38 oldtos = iph->tos;
39 iph->tos &= ~IPT_ECN_IP_MASK;
40 iph->tos |= (einfo->ip_ect & IPT_ECN_IP_MASK);
be0ea7d5 41 csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
e905a9ed 42 }
e1931b78 43 return true;
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44}
45
e1931b78
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46/* Return false if there was an error. */
47static inline bool
3db05fea 48set_ect_tcp(struct sk_buff *skb, const struct ipt_ECN_info *einfo)
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49{
50 struct tcphdr _tcph, *tcph;
6a19d614 51 __be16 oldval;
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52
53 /* Not enought header? */
3db05fea 54 tcph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
1da177e4 55 if (!tcph)
e1931b78 56 return false;
1da177e4 57
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58 if ((!(einfo->operation & IPT_ECN_OP_SET_ECE) ||
59 tcph->ece == einfo->proto.tcp.ece) &&
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60 (!(einfo->operation & IPT_ECN_OP_SET_CWR) ||
61 tcph->cwr == einfo->proto.tcp.cwr))
e1931b78 62 return true;
1da177e4 63
3db05fea 64 if (!skb_make_writable(skb, ip_hdrlen(skb) + sizeof(*tcph)))
e1931b78 65 return false;
3db05fea 66 tcph = (void *)ip_hdr(skb) + ip_hdrlen(skb);
1da177e4 67
6a19d614 68 oldval = ((__be16 *)tcph)[6];
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69 if (einfo->operation & IPT_ECN_OP_SET_ECE)
70 tcph->ece = einfo->proto.tcp.ece;
71 if (einfo->operation & IPT_ECN_OP_SET_CWR)
72 tcph->cwr = einfo->proto.tcp.cwr;
1da177e4 73
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74 inet_proto_csum_replace2(&tcph->check, skb,
75 oldval, ((__be16 *)tcph)[6], 0);
e1931b78 76 return true;
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77}
78
79static unsigned int
d3c5ee6d
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80ecn_tg(struct sk_buff *skb, const struct net_device *in,
81 const struct net_device *out, unsigned int hooknum,
82 const struct xt_target *target, const void *targinfo)
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83{
84 const struct ipt_ECN_info *einfo = targinfo;
85
86 if (einfo->operation & IPT_ECN_OP_SET_IP)
3db05fea 87 if (!set_ect_ip(skb, einfo))
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88 return NF_DROP;
89
90 if (einfo->operation & (IPT_ECN_OP_SET_ECE | IPT_ECN_OP_SET_CWR)
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HX
91 && ip_hdr(skb)->protocol == IPPROTO_TCP)
92 if (!set_ect_tcp(skb, einfo))
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93 return NF_DROP;
94
6709dbbb 95 return XT_CONTINUE;
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96}
97
e1931b78 98static bool
d3c5ee6d
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99ecn_tg_check(const char *tablename, const void *e_void,
100 const struct xt_target *target, void *targinfo,
101 unsigned int hook_mask)
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102{
103 const struct ipt_ECN_info *einfo = (struct ipt_ECN_info *)targinfo;
2e4e6a17 104 const struct ipt_entry *e = e_void;
1da177e4 105
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106 if (einfo->operation & IPT_ECN_OP_MASK) {
107 printk(KERN_WARNING "ECN: unsupported ECN operation %x\n",
108 einfo->operation);
e1931b78 109 return false;
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110 }
111 if (einfo->ip_ect & ~IPT_ECN_IP_MASK) {
112 printk(KERN_WARNING "ECN: new ECT codepoint %x out of mask\n",
113 einfo->ip_ect);
e1931b78 114 return false;
1da177e4 115 }
1da177e4 116 if ((einfo->operation & (IPT_ECN_OP_SET_ECE|IPT_ECN_OP_SET_CWR))
6709dbbb 117 && (e->ip.proto != IPPROTO_TCP || (e->ip.invflags & XT_INV_PROTO))) {
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118 printk(KERN_WARNING "ECN: cannot use TCP operations on a "
119 "non-tcp rule\n");
e1931b78 120 return false;
1da177e4 121 }
e1931b78 122 return true;
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123}
124
d3c5ee6d 125static struct xt_target ecn_tg_reg __read_mostly = {
1da177e4 126 .name = "ECN",
6709dbbb 127 .family = AF_INET,
d3c5ee6d 128 .target = ecn_tg,
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PM
129 .targetsize = sizeof(struct ipt_ECN_info),
130 .table = "mangle",
d3c5ee6d 131 .checkentry = ecn_tg_check,
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132 .me = THIS_MODULE,
133};
134
d3c5ee6d 135static int __init ecn_tg_init(void)
1da177e4 136{
d3c5ee6d 137 return xt_register_target(&ecn_tg_reg);
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138}
139
d3c5ee6d 140static void __exit ecn_tg_exit(void)
1da177e4 141{
d3c5ee6d 142 xt_unregister_target(&ecn_tg_reg);
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143}
144
d3c5ee6d
JE
145module_init(ecn_tg_init);
146module_exit(ecn_tg_exit);
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