1/* IP tables module for matching the value of the IPv4/IPv6 DSCP field
2 *
3 * (C) 2002 by Harald Welte <laforge@netfilter.org>
4 *
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.
8 */
9
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/ip.h>
13#include <linux/ipv6.h>
14#include <net/dsfield.h>
15
16#include <linux/netfilter/xt_dscp.h>
17#include <linux/netfilter/x_tables.h>
18
19MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
20MODULE_DESCRIPTION("x_tables DSCP matching module");
21MODULE_LICENSE("GPL");
22MODULE_ALIAS("ipt_dscp");
23MODULE_ALIAS("ip6t_dscp");
24
25static int match(const struct sk_buff *skb,
26		 const struct net_device *in,
27		 const struct net_device *out,
28		 const struct xt_match *match,
29		 const void *matchinfo,
30		 int offset,
31		 unsigned int protoff,
32		 int *hotdrop)
33{
34	const struct xt_dscp_info *info = matchinfo;
35	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
36
37	return (dscp == info->dscp) ^ !!info->invert;
38}
39
40static int match6(const struct sk_buff *skb,
41		  const struct net_device *in,
42		  const struct net_device *out,
43		  const struct xt_match *match,
44		  const void *matchinfo,
45		  int offset,
46		  unsigned int protoff,
47		  int *hotdrop)
48{
49	const struct xt_dscp_info *info = matchinfo;
50	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
51
52	return (dscp == info->dscp) ^ !!info->invert;
53}
54
55static int checkentry(const char *tablename,
56		      const void *info,
57		      const struct xt_match *match,
58		      void *matchinfo,
59		      unsigned int hook_mask)
60{
61	const u_int8_t dscp = ((struct xt_dscp_info *)matchinfo)->dscp;
62
63	if (dscp > XT_DSCP_MAX) {
64		printk(KERN_ERR "xt_dscp: dscp %x out of range\n", dscp);
65		return 0;
66	}
67
68	return 1;
69}
70
71static struct xt_match xt_dscp_match[] = {
72	{
73		.name		= "dscp",
74		.family		= AF_INET,
75		.checkentry	= checkentry,
76		.match		= match,
77		.matchsize	= sizeof(struct xt_dscp_info),
78		.me		= THIS_MODULE,
79	},
80	{
81		.name		= "dscp",
82		.family		= AF_INET6,
83		.checkentry	= checkentry,
84		.match		= match6,
85		.matchsize	= sizeof(struct xt_dscp_info),
86		.me		= THIS_MODULE,
87	},
88};
89
90static int __init xt_dscp_match_init(void)
91{
92	return xt_register_matches(xt_dscp_match, ARRAY_SIZE(xt_dscp_match));
93}
94
95static void __exit xt_dscp_match_fini(void)
96{
97	xt_unregister_matches(xt_dscp_match, ARRAY_SIZE(xt_dscp_match));
98}
99
100module_init(xt_dscp_match_init);
101module_exit(xt_dscp_match_fini);
102