1// SPDX-License-Identifier: GPL-2.0-only
2/* IP tables module for matching the value of the IPv4/IPv6 DSCP field
3 *
4 * (C) 2002 by Harald Welte <laforge@netfilter.org>
5 */
6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7#include <linux/module.h>
8#include <linux/skbuff.h>
9#include <linux/ip.h>
10#include <linux/ipv6.h>
11#include <net/dsfield.h>
12
13#include <linux/netfilter/x_tables.h>
14#include <linux/netfilter/xt_dscp.h>
15
16MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
17MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
18MODULE_LICENSE("GPL");
19MODULE_ALIAS("ipt_dscp");
20MODULE_ALIAS("ip6t_dscp");
21MODULE_ALIAS("ipt_tos");
22MODULE_ALIAS("ip6t_tos");
23
24static bool
25dscp_mt(const struct sk_buff *skb, struct xt_action_param *par)
26{
27	const struct xt_dscp_info *info = par->matchinfo;
28	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
29
30	return (dscp == info->dscp) ^ !!info->invert;
31}
32
33static bool
34dscp_mt6(const struct sk_buff *skb, struct xt_action_param *par)
35{
36	const struct xt_dscp_info *info = par->matchinfo;
37	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
38
39	return (dscp == info->dscp) ^ !!info->invert;
40}
41
42static int dscp_mt_check(const struct xt_mtchk_param *par)
43{
44	const struct xt_dscp_info *info = par->matchinfo;
45
46	if (info->dscp > XT_DSCP_MAX)
47		return -EDOM;
48
49	return 0;
50}
51
52static bool tos_mt(const struct sk_buff *skb, struct xt_action_param *par)
53{
54	const struct xt_tos_match_info *info = par->matchinfo;
55
56	if (xt_family(par) == NFPROTO_IPV4)
57		return ((ip_hdr(skb)->tos & info->tos_mask) ==
58		       info->tos_value) ^ !!info->invert;
59	else
60		return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
61		       info->tos_value) ^ !!info->invert;
62}
63
64static struct xt_match dscp_mt_reg[] __read_mostly = {
65	{
66		.name		= "dscp",
67		.family		= NFPROTO_IPV4,
68		.checkentry	= dscp_mt_check,
69		.match		= dscp_mt,
70		.matchsize	= sizeof(struct xt_dscp_info),
71		.me		= THIS_MODULE,
72	},
73	{
74		.name		= "dscp",
75		.family		= NFPROTO_IPV6,
76		.checkentry	= dscp_mt_check,
77		.match		= dscp_mt6,
78		.matchsize	= sizeof(struct xt_dscp_info),
79		.me		= THIS_MODULE,
80	},
81	{
82		.name		= "tos",
83		.revision	= 1,
84		.family		= NFPROTO_IPV4,
85		.match		= tos_mt,
86		.matchsize	= sizeof(struct xt_tos_match_info),
87		.me		= THIS_MODULE,
88	},
89	{
90		.name		= "tos",
91		.revision	= 1,
92		.family		= NFPROTO_IPV6,
93		.match		= tos_mt,
94		.matchsize	= sizeof(struct xt_tos_match_info),
95		.me		= THIS_MODULE,
96	},
97};
98
99static int __init dscp_mt_init(void)
100{
101	return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
102}
103
104static void __exit dscp_mt_exit(void)
105{
106	xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
107}
108
109module_init(dscp_mt_init);
110module_exit(dscp_mt_exit);
111