xref: /openbmc/linux/net/netfilter/xt_DSCP.c (revision 168141f7)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8
3  *
4  * (C) 2002 by Harald Welte <laforge@netfilter.org>
5  * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
6  *
7  * See RFC2474 for a description of the DSCP field within the IP Header.
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 modification");
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 #define XT_DSCP_ECN_MASK	3u
28 
29 static unsigned int
dscp_tg(struct sk_buff * skb,const struct xt_action_param * par)30 dscp_tg(struct sk_buff *skb, const struct xt_action_param *par)
31 {
32 	const struct xt_DSCP_info *dinfo = par->targinfo;
33 	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
34 
35 	if (dscp != dinfo->dscp) {
36 		if (skb_ensure_writable(skb, sizeof(struct iphdr)))
37 			return NF_DROP;
38 
39 		ipv4_change_dsfield(ip_hdr(skb), XT_DSCP_ECN_MASK,
40 				    dinfo->dscp << XT_DSCP_SHIFT);
41 
42 	}
43 	return XT_CONTINUE;
44 }
45 
46 static unsigned int
dscp_tg6(struct sk_buff * skb,const struct xt_action_param * par)47 dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par)
48 {
49 	const struct xt_DSCP_info *dinfo = par->targinfo;
50 	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
51 
52 	if (dscp != dinfo->dscp) {
53 		if (skb_ensure_writable(skb, sizeof(struct ipv6hdr)))
54 			return NF_DROP;
55 
56 		ipv6_change_dsfield(ipv6_hdr(skb), XT_DSCP_ECN_MASK,
57 				    dinfo->dscp << XT_DSCP_SHIFT);
58 	}
59 	return XT_CONTINUE;
60 }
61 
dscp_tg_check(const struct xt_tgchk_param * par)62 static int dscp_tg_check(const struct xt_tgchk_param *par)
63 {
64 	const struct xt_DSCP_info *info = par->targinfo;
65 
66 	if (info->dscp > XT_DSCP_MAX)
67 		return -EDOM;
68 	return 0;
69 }
70 
71 static unsigned int
tos_tg(struct sk_buff * skb,const struct xt_action_param * par)72 tos_tg(struct sk_buff *skb, const struct xt_action_param *par)
73 {
74 	const struct xt_tos_target_info *info = par->targinfo;
75 	struct iphdr *iph = ip_hdr(skb);
76 	u_int8_t orig, nv;
77 
78 	orig = ipv4_get_dsfield(iph);
79 	nv   = (orig & ~info->tos_mask) ^ info->tos_value;
80 
81 	if (orig != nv) {
82 		if (skb_ensure_writable(skb, sizeof(struct iphdr)))
83 			return NF_DROP;
84 		iph = ip_hdr(skb);
85 		ipv4_change_dsfield(iph, 0, nv);
86 	}
87 
88 	return XT_CONTINUE;
89 }
90 
91 static unsigned int
tos_tg6(struct sk_buff * skb,const struct xt_action_param * par)92 tos_tg6(struct sk_buff *skb, const struct xt_action_param *par)
93 {
94 	const struct xt_tos_target_info *info = par->targinfo;
95 	struct ipv6hdr *iph = ipv6_hdr(skb);
96 	u_int8_t orig, nv;
97 
98 	orig = ipv6_get_dsfield(iph);
99 	nv   = (orig & ~info->tos_mask) ^ info->tos_value;
100 
101 	if (orig != nv) {
102 		if (skb_ensure_writable(skb, sizeof(struct iphdr)))
103 			return NF_DROP;
104 		iph = ipv6_hdr(skb);
105 		ipv6_change_dsfield(iph, 0, nv);
106 	}
107 
108 	return XT_CONTINUE;
109 }
110 
111 static struct xt_target dscp_tg_reg[] __read_mostly = {
112 	{
113 		.name		= "DSCP",
114 		.family		= NFPROTO_IPV4,
115 		.checkentry	= dscp_tg_check,
116 		.target		= dscp_tg,
117 		.targetsize	= sizeof(struct xt_DSCP_info),
118 		.table		= "mangle",
119 		.me		= THIS_MODULE,
120 	},
121 	{
122 		.name		= "DSCP",
123 		.family		= NFPROTO_IPV6,
124 		.checkentry	= dscp_tg_check,
125 		.target		= dscp_tg6,
126 		.targetsize	= sizeof(struct xt_DSCP_info),
127 		.table		= "mangle",
128 		.me		= THIS_MODULE,
129 	},
130 	{
131 		.name		= "TOS",
132 		.revision	= 1,
133 		.family		= NFPROTO_IPV4,
134 		.table		= "mangle",
135 		.target		= tos_tg,
136 		.targetsize	= sizeof(struct xt_tos_target_info),
137 		.me		= THIS_MODULE,
138 	},
139 	{
140 		.name		= "TOS",
141 		.revision	= 1,
142 		.family		= NFPROTO_IPV6,
143 		.table		= "mangle",
144 		.target		= tos_tg6,
145 		.targetsize	= sizeof(struct xt_tos_target_info),
146 		.me		= THIS_MODULE,
147 	},
148 };
149 
dscp_tg_init(void)150 static int __init dscp_tg_init(void)
151 {
152 	return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
153 }
154 
dscp_tg_exit(void)155 static void __exit dscp_tg_exit(void)
156 {
157 	xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
158 }
159 
160 module_init(dscp_tg_init);
161 module_exit(dscp_tg_exit);
162