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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/x_tables.h>
17#include <linux/netfilter/xt_dscp.h>
18
19MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
20MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
21MODULE_LICENSE("GPL");
22MODULE_ALIAS("ipt_dscp");
23MODULE_ALIAS("ip6t_dscp");
24MODULE_ALIAS("ipt_tos");
25MODULE_ALIAS("ip6t_tos");
26
27static bool
28dscp_mt(const struct sk_buff *skb, struct xt_action_param *par)
29{
30	const struct xt_dscp_info *info = par->matchinfo;
31	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
32
33	return (dscp == info->dscp) ^ !!info->invert;
34}
35
36static bool
37dscp_mt6(const struct sk_buff *skb, struct xt_action_param *par)
38{
39	const struct xt_dscp_info *info = par->matchinfo;
40	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
41
42	return (dscp == info->dscp) ^ !!info->invert;
43}
44
45static int dscp_mt_check(const struct xt_mtchk_param *par)
46{
47	const struct xt_dscp_info *info = par->matchinfo;
48
49	if (info->dscp > XT_DSCP_MAX) {
50		pr_info("dscp %x out of range\n", info->dscp);
51		return -EDOM;
52	}
53
54	return 0;
55}
56
57static bool tos_mt(const struct sk_buff *skb, struct xt_action_param *par)
58{
59	const struct xt_tos_match_info *info = par->matchinfo;
60
61	if (par->family == NFPROTO_IPV4)
62		return ((ip_hdr(skb)->tos & info->tos_mask) ==
63		       info->tos_value) ^ !!info->invert;
64	else
65		return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
66		       info->tos_value) ^ !!info->invert;
67}
68
69static struct xt_match dscp_mt_reg[] __read_mostly = {
70	{
71		.name		= "dscp",
72		.family		= NFPROTO_IPV4,
73		.checkentry	= dscp_mt_check,
74		.match		= dscp_mt,
75		.matchsize	= sizeof(struct xt_dscp_info),
76		.me		= THIS_MODULE,
77	},
78	{
79		.name		= "dscp",
80		.family		= NFPROTO_IPV6,
81		.checkentry	= dscp_mt_check,
82		.match		= dscp_mt6,
83		.matchsize	= sizeof(struct xt_dscp_info),
84		.me		= THIS_MODULE,
85	},
86	{
87		.name		= "tos",
88		.revision	= 1,
89		.family		= NFPROTO_IPV4,
90		.match		= tos_mt,
91		.matchsize	= sizeof(struct xt_tos_match_info),
92		.me		= THIS_MODULE,
93	},
94	{
95		.name		= "tos",
96		.revision	= 1,
97		.family		= NFPROTO_IPV6,
98		.match		= tos_mt,
99		.matchsize	= sizeof(struct xt_tos_match_info),
100		.me		= THIS_MODULE,
101	},
102};
103
104static int __init dscp_mt_init(void)
105{
106	return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
107}
108
109static void __exit dscp_mt_exit(void)
110{
111	xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
112}
113
114module_init(dscp_mt_init);
115module_exit(dscp_mt_exit);
116