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
19 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
20 MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
21 MODULE_LICENSE("GPL");
22 MODULE_ALIAS("ipt_dscp");
23 MODULE_ALIAS("ip6t_dscp");
24 MODULE_ALIAS("ipt_tos");
25 MODULE_ALIAS("ip6t_tos");
26
27 static bool
dscp_mt(const struct sk_buff * skb,struct xt_action_param * par)28 dscp_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
36 static bool
dscp_mt6(const struct sk_buff * skb,struct xt_action_param * par)37 dscp_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
dscp_mt_check(const struct xt_mtchk_param * par)45 static 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 return -EDOM;
51
52 return 0;
53 }
54
tos_mt(const struct sk_buff * skb,struct xt_action_param * par)55 static bool tos_mt(const struct sk_buff *skb, struct xt_action_param *par)
56 {
57 const struct xt_tos_match_info *info = par->matchinfo;
58
59 if (xt_family(par) == NFPROTO_IPV4)
60 return ((ip_hdr(skb)->tos & info->tos_mask) ==
61 info->tos_value) ^ !!info->invert;
62 else
63 return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
64 info->tos_value) ^ !!info->invert;
65 }
66
67 static struct xt_match dscp_mt_reg[] __read_mostly = {
68 {
69 .name = "dscp",
70 .family = NFPROTO_IPV4,
71 .checkentry = dscp_mt_check,
72 .match = dscp_mt,
73 .matchsize = sizeof(struct xt_dscp_info),
74 .me = THIS_MODULE,
75 },
76 {
77 .name = "dscp",
78 .family = NFPROTO_IPV6,
79 .checkentry = dscp_mt_check,
80 .match = dscp_mt6,
81 .matchsize = sizeof(struct xt_dscp_info),
82 .me = THIS_MODULE,
83 },
84 {
85 .name = "tos",
86 .revision = 1,
87 .family = NFPROTO_IPV4,
88 .match = tos_mt,
89 .matchsize = sizeof(struct xt_tos_match_info),
90 .me = THIS_MODULE,
91 },
92 {
93 .name = "tos",
94 .revision = 1,
95 .family = NFPROTO_IPV6,
96 .match = tos_mt,
97 .matchsize = sizeof(struct xt_tos_match_info),
98 .me = THIS_MODULE,
99 },
100 };
101
dscp_mt_init(void)102 static int __init dscp_mt_init(void)
103 {
104 return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
105 }
106
dscp_mt_exit(void)107 static void __exit dscp_mt_exit(void)
108 {
109 xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
110 }
111
112 module_init(dscp_mt_init);
113 module_exit(dscp_mt_exit);
114
