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 
16 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
17 MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
18 MODULE_LICENSE("GPL");
19 MODULE_ALIAS("ipt_dscp");
20 MODULE_ALIAS("ip6t_dscp");
21 MODULE_ALIAS("ipt_tos");
22 MODULE_ALIAS("ip6t_tos");
23 
24 static bool
dscp_mt(const struct sk_buff * skb,struct xt_action_param * par)25 dscp_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 
33 static bool
dscp_mt6(const struct sk_buff * skb,struct xt_action_param * par)34 dscp_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 
dscp_mt_check(const struct xt_mtchk_param * par)42 static 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 
tos_mt(const struct sk_buff * skb,struct xt_action_param * par)52 static 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 
64 static 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 
dscp_mt_init(void)99 static int __init dscp_mt_init(void)
100 {
101 	return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
102 }
103 
dscp_mt_exit(void)104 static void __exit dscp_mt_exit(void)
105 {
106 	xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
107 }
108 
109 module_init(dscp_mt_init);
110 module_exit(dscp_mt_exit);
111