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
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 #include <linux/netfilter_ipv4/ipt_TOS.h>
22
23 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
24 MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
25 MODULE_LICENSE("GPL");
26 MODULE_ALIAS("ipt_DSCP");
27 MODULE_ALIAS("ip6t_DSCP");
28 MODULE_ALIAS("ipt_TOS");
29 MODULE_ALIAS("ip6t_TOS");
30
31 static unsigned int
dscp_tg(struct sk_buff * skb,const struct xt_target_param * par)32 dscp_tg(struct sk_buff *skb, const struct xt_target_param *par)
33 {
34 const struct xt_DSCP_info *dinfo = par->targinfo;
35 u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
36
37 if (dscp != dinfo->dscp) {
38 if (!skb_make_writable(skb, sizeof(struct iphdr)))
39 return NF_DROP;
40
41 ipv4_change_dsfield(ip_hdr(skb), (__u8)(~XT_DSCP_MASK),
42 dinfo->dscp << XT_DSCP_SHIFT);
43
44 }
45 return XT_CONTINUE;
46 }
47
48 static unsigned int
dscp_tg6(struct sk_buff * skb,const struct xt_target_param * par)49 dscp_tg6(struct sk_buff *skb, const struct xt_target_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), (__u8)(~XT_DSCP_MASK),
59 dinfo->dscp << XT_DSCP_SHIFT);
60 }
61 return XT_CONTINUE;
62 }
63
dscp_tg_check(const struct xt_tgchk_param * par)64 static bool dscp_tg_check(const struct xt_tgchk_param *par)
65 {
66 const struct xt_DSCP_info *info = par->targinfo;
67
68 if (info->dscp > XT_DSCP_MAX) {
69 printk(KERN_WARNING "DSCP: dscp %x out of range\n", info->dscp);
70 return false;
71 }
72 return true;
73 }
74
75 static unsigned int
tos_tg_v0(struct sk_buff * skb,const struct xt_target_param * par)76 tos_tg_v0(struct sk_buff *skb, const struct xt_target_param *par)
77 {
78 const struct ipt_tos_target_info *info = par->targinfo;
79 struct iphdr *iph = ip_hdr(skb);
80 u_int8_t oldtos;
81
82 if ((iph->tos & IPTOS_TOS_MASK) != info->tos) {
83 if (!skb_make_writable(skb, sizeof(struct iphdr)))
84 return NF_DROP;
85
86 iph = ip_hdr(skb);
87 oldtos = iph->tos;
88 iph->tos = (iph->tos & IPTOS_PREC_MASK) | info->tos;
89 csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
90 }
91
92 return XT_CONTINUE;
93 }
94
tos_tg_check_v0(const struct xt_tgchk_param * par)95 static bool tos_tg_check_v0(const struct xt_tgchk_param *par)
96 {
97 const struct ipt_tos_target_info *info = par->targinfo;
98 const uint8_t tos = info->tos;
99
100 if (tos != IPTOS_LOWDELAY && tos != IPTOS_THROUGHPUT &&
101 tos != IPTOS_RELIABILITY && tos != IPTOS_MINCOST &&
102 tos != IPTOS_NORMALSVC) {
103 printk(KERN_WARNING "TOS: bad tos value %#x\n", tos);
104 return false;
105 }
106
107 return true;
108 }
109
110 static unsigned int
tos_tg(struct sk_buff * skb,const struct xt_target_param * par)111 tos_tg(struct sk_buff *skb, const struct xt_target_param *par)
112 {
113 const struct xt_tos_target_info *info = par->targinfo;
114 struct iphdr *iph = ip_hdr(skb);
115 u_int8_t orig, nv;
116
117 orig = ipv4_get_dsfield(iph);
118 nv = (orig & ~info->tos_mask) ^ info->tos_value;
119
120 if (orig != nv) {
121 if (!skb_make_writable(skb, sizeof(struct iphdr)))
122 return NF_DROP;
123 iph = ip_hdr(skb);
124 ipv4_change_dsfield(iph, 0, nv);
125 }
126
127 return XT_CONTINUE;
128 }
129
130 static unsigned int
tos_tg6(struct sk_buff * skb,const struct xt_target_param * par)131 tos_tg6(struct sk_buff *skb, const struct xt_target_param *par)
132 {
133 const struct xt_tos_target_info *info = par->targinfo;
134 struct ipv6hdr *iph = ipv6_hdr(skb);
135 u_int8_t orig, nv;
136
137 orig = ipv6_get_dsfield(iph);
138 nv = (orig & info->tos_mask) ^ info->tos_value;
139
140 if (orig != nv) {
141 if (!skb_make_writable(skb, sizeof(struct iphdr)))
142 return NF_DROP;
143 iph = ipv6_hdr(skb);
144 ipv6_change_dsfield(iph, 0, nv);
145 }
146
147 return XT_CONTINUE;
148 }
149
150 static struct xt_target dscp_tg_reg[] __read_mostly = {
151 {
152 .name = "DSCP",
153 .family = NFPROTO_IPV4,
154 .checkentry = dscp_tg_check,
155 .target = dscp_tg,
156 .targetsize = sizeof(struct xt_DSCP_info),
157 .table = "mangle",
158 .me = THIS_MODULE,
159 },
160 {
161 .name = "DSCP",
162 .family = NFPROTO_IPV6,
163 .checkentry = dscp_tg_check,
164 .target = dscp_tg6,
165 .targetsize = sizeof(struct xt_DSCP_info),
166 .table = "mangle",
167 .me = THIS_MODULE,
168 },
169 {
170 .name = "TOS",
171 .revision = 0,
172 .family = NFPROTO_IPV4,
173 .table = "mangle",
174 .target = tos_tg_v0,
175 .targetsize = sizeof(struct ipt_tos_target_info),
176 .checkentry = tos_tg_check_v0,
177 .me = THIS_MODULE,
178 },
179 {
180 .name = "TOS",
181 .revision = 1,
182 .family = NFPROTO_IPV4,
183 .table = "mangle",
184 .target = tos_tg,
185 .targetsize = sizeof(struct xt_tos_target_info),
186 .me = THIS_MODULE,
187 },
188 {
189 .name = "TOS",
190 .revision = 1,
191 .family = NFPROTO_IPV6,
192 .table = "mangle",
193 .target = tos_tg6,
194 .targetsize = sizeof(struct xt_tos_target_info),
195 .me = THIS_MODULE,
196 },
197 };
198
dscp_tg_init(void)199 static int __init dscp_tg_init(void)
200 {
201 return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
202 }
203
dscp_tg_exit(void)204 static void __exit dscp_tg_exit(void)
205 {
206 xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
207 }
208
209 module_init(dscp_tg_init);
210 module_exit(dscp_tg_exit);
211