1/* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8
2 *
3 * (C) 2002 by Harald Welte <laforge@netfilter.org>
4 * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * See RFC2474 for a description of the DSCP field within the IP Header.
11*/
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13#include <linux/module.h>
14#include <linux/skbuff.h>
15#include <linux/ip.h>
16#include <linux/ipv6.h>
17#include <net/dsfield.h>
18
19#include <linux/netfilter/x_tables.h>
20#include <linux/netfilter/xt_DSCP.h>
21
22MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
23MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
24MODULE_LICENSE("GPL");
25MODULE_ALIAS("ipt_DSCP");
26MODULE_ALIAS("ip6t_DSCP");
27MODULE_ALIAS("ipt_TOS");
28MODULE_ALIAS("ip6t_TOS");
29
30static unsigned int
31dscp_tg(struct sk_buff *skb, const struct xt_action_param *par)
32{
33	const struct xt_DSCP_info *dinfo = par->targinfo;
34	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
35
36	if (dscp != dinfo->dscp) {
37		if (!skb_make_writable(skb, sizeof(struct iphdr)))
38			return NF_DROP;
39
40		ipv4_change_dsfield(ip_hdr(skb),
41				    (__force __u8)(~XT_DSCP_MASK),
42				    dinfo->dscp << XT_DSCP_SHIFT);
43
44	}
45	return XT_CONTINUE;
46}
47
48static unsigned int
49dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par)
50{
51	const struct xt_DSCP_info *dinfo = par->targinfo;
52	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
53
54	if (dscp != dinfo->dscp) {
55		if (!skb_make_writable(skb, sizeof(struct ipv6hdr)))
56			return NF_DROP;
57
58		ipv6_change_dsfield(ipv6_hdr(skb),
59				    (__force __u8)(~XT_DSCP_MASK),
60				    dinfo->dscp << XT_DSCP_SHIFT);
61	}
62	return XT_CONTINUE;
63}
64
65static int dscp_tg_check(const struct xt_tgchk_param *par)
66{
67	const struct xt_DSCP_info *info = par->targinfo;
68
69	if (info->dscp > XT_DSCP_MAX) {
70		pr_info("dscp %x out of range\n", info->dscp);
71		return -EDOM;
72	}
73	return 0;
74}
75
76static unsigned int
77tos_tg(struct sk_buff *skb, const struct xt_action_param *par)
78{
79	const struct xt_tos_target_info *info = par->targinfo;
80	struct iphdr *iph = ip_hdr(skb);
81	u_int8_t orig, nv;
82
83	orig = ipv4_get_dsfield(iph);
84	nv   = (orig & ~info->tos_mask) ^ info->tos_value;
85
86	if (orig != nv) {
87		if (!skb_make_writable(skb, sizeof(struct iphdr)))
88			return NF_DROP;
89		iph = ip_hdr(skb);
90		ipv4_change_dsfield(iph, 0, nv);
91	}
92
93	return XT_CONTINUE;
94}
95
96static unsigned int
97tos_tg6(struct sk_buff *skb, const struct xt_action_param *par)
98{
99	const struct xt_tos_target_info *info = par->targinfo;
100	struct ipv6hdr *iph = ipv6_hdr(skb);
101	u_int8_t orig, nv;
102
103	orig = ipv6_get_dsfield(iph);
104	nv   = (orig & ~info->tos_mask) ^ info->tos_value;
105
106	if (orig != nv) {
107		if (!skb_make_writable(skb, sizeof(struct iphdr)))
108			return NF_DROP;
109		iph = ipv6_hdr(skb);
110		ipv6_change_dsfield(iph, 0, nv);
111	}
112
113	return XT_CONTINUE;
114}
115
116static struct xt_target dscp_tg_reg[] __read_mostly = {
117	{
118		.name		= "DSCP",
119		.family		= NFPROTO_IPV4,
120		.checkentry	= dscp_tg_check,
121		.target		= dscp_tg,
122		.targetsize	= sizeof(struct xt_DSCP_info),
123		.table		= "mangle",
124		.me		= THIS_MODULE,
125	},
126	{
127		.name		= "DSCP",
128		.family		= NFPROTO_IPV6,
129		.checkentry	= dscp_tg_check,
130		.target		= dscp_tg6,
131		.targetsize	= sizeof(struct xt_DSCP_info),
132		.table		= "mangle",
133		.me		= THIS_MODULE,
134	},
135	{
136		.name		= "TOS",
137		.revision	= 1,
138		.family		= NFPROTO_IPV4,
139		.table		= "mangle",
140		.target		= tos_tg,
141		.targetsize	= sizeof(struct xt_tos_target_info),
142		.me		= THIS_MODULE,
143	},
144	{
145		.name		= "TOS",
146		.revision	= 1,
147		.family		= NFPROTO_IPV6,
148		.table		= "mangle",
149		.target		= tos_tg6,
150		.targetsize	= sizeof(struct xt_tos_target_info),
151		.me		= THIS_MODULE,
152	},
153};
154
155static int __init dscp_tg_init(void)
156{
157	return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
158}
159
160static void __exit dscp_tg_exit(void)
161{
162	xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
163}
164
165module_init(dscp_tg_init);
166module_exit(dscp_tg_exit);
167