aboutsummaryrefslogtreecommitdiff
path: root/net/netfilter/xt_DSCP.c
blob: ae8271652efa9cf5a6f939fcedc3238ca6c865c7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
/* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8
 *
 * (C) 2002 by Harald Welte <laforge@netfilter.org>
 * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * See RFC2474 for a description of the DSCP field within the IP Header.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <net/dsfield.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_DSCP.h>

MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_DSCP");
MODULE_ALIAS("ip6t_DSCP");
MODULE_ALIAS("ipt_TOS");
MODULE_ALIAS("ip6t_TOS");

static unsigned int
dscp_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_DSCP_info *dinfo = par->targinfo;
	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;

	if (dscp != dinfo->dscp) {
		if (!skb_make_writable(skb, sizeof(struct iphdr)))
			return NF_DROP;

		ipv4_change_dsfield(ip_hdr(skb), (__u8)(~XT_DSCP_MASK),
				    dinfo->dscp << XT_DSCP_SHIFT);

	}
	return XT_CONTINUE;
}

static unsigned int
dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_DSCP_info *dinfo = par->targinfo;
	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;

	if (dscp != dinfo->dscp) {
		if (!skb_make_writable(skb, sizeof(struct ipv6hdr)))
			return NF_DROP;

		ipv6_change_dsfield(ipv6_hdr(skb), (__u8)(~XT_DSCP_MASK),
				    dinfo->dscp << XT_DSCP_SHIFT);
	}
	return XT_CONTINUE;
}

static int dscp_tg_check(const struct xt_tgchk_param *par)
{
	const struct xt_DSCP_info *info = par->targinfo;

	if (info->dscp > XT_DSCP_MAX) {
		pr_info("dscp %x out of range\n", info->dscp);
		return -EDOM;
	}
	return 0;
}

static unsigned int
tos_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_tos_target_info *info = par->targinfo;
	struct iphdr *iph = ip_hdr(skb);
	u_int8_t orig, nv;

	orig = ipv4_get_dsfield(iph);
	nv   = (orig & ~info->tos_mask) ^ info->tos_value;

	if (orig != nv) {
		if (!skb_make_writable(skb, sizeof(struct iphdr)))
			return NF_DROP;
		iph = ip_hdr(skb);
		ipv4_change_dsfield(iph, 0, nv);
	}

	return XT_CONTINUE;
}

static unsigned int
tos_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_tos_target_info *info = par->targinfo;
	struct ipv6hdr *iph = ipv6_hdr(skb);
	u_int8_t orig, nv;

	orig = ipv6_get_dsfield(iph);
	nv   = (orig & ~info->tos_mask) ^ info->tos_value;

	if (orig != nv) {
		if (!skb_make_writable(skb, sizeof(struct iphdr)))
			return NF_DROP;
		iph = ipv6_hdr(skb);
		ipv6_change_dsfield(iph, 0, nv);
	}

	return XT_CONTINUE;
}

static struct xt_target dscp_tg_reg[] __read_mostly = {
	{
		.name		= "DSCP",
		.family		= NFPROTO_IPV4,
		.checkentry	= dscp_tg_check,
		.target		= dscp_tg,
		.targetsize	= sizeof(struct xt_DSCP_info),
		.table		= "mangle",
		.me		= THIS_MODULE,
	},
	{
		.name		= "DSCP",
		.family		= NFPROTO_IPV6,
		.checkentry	= dscp_tg_check,
		.target		= dscp_tg6,
		.targetsize	= sizeof(struct xt_DSCP_info),
		.table		= "mangle",
		.me		= THIS_MODULE,
	},
	{
		.name		= "TOS",
		.revision	= 1,
		.family		= NFPROTO_IPV4,
		.table		= "mangle",
		.target		= tos_tg,
		.targetsize	= sizeof(struct xt_tos_target_info),
		.me		= THIS_MODULE,
	},
	{
		.name		= "TOS",
		.revision	= 1,
		.family		= NFPROTO_IPV6,
		.table		= "mangle",
		.target		= tos_tg6,
		.targetsize	= sizeof(struct xt_tos_target_info),
		.me		= THIS_MODULE,
	},
};

static int __init dscp_tg_init(void)
{
	return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
}

static void __exit dscp_tg_exit(void)
{
	xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
}

module_init(dscp_tg_init);
module_exit(dscp_tg_exit);