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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 | static unsigned int | |
28 | dscp_tg(struct sk_buff *skb, const struct xt_action_param *par) | |
29 | { | |
30 | const struct xt_DSCP_info *dinfo = par->targinfo; | |
31 | u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT; | |
32 | ||
33 | if (dscp != dinfo->dscp) { | |
34 | if (skb_ensure_writable(skb, sizeof(struct iphdr))) | |
35 | return NF_DROP; | |
36 | ||
37 | ipv4_change_dsfield(ip_hdr(skb), | |
38 | (__force __u8)(~XT_DSCP_MASK), | |
39 | dinfo->dscp << XT_DSCP_SHIFT); | |
40 | ||
41 | } | |
42 | return XT_CONTINUE; | |
43 | } | |
44 | ||
45 | static unsigned int | |
46 | dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par) | |
47 | { | |
48 | const struct xt_DSCP_info *dinfo = par->targinfo; | |
49 | u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT; | |
50 | ||
51 | if (dscp != dinfo->dscp) { | |
52 | if (skb_ensure_writable(skb, sizeof(struct ipv6hdr))) | |
53 | return NF_DROP; | |
54 | ||
55 | ipv6_change_dsfield(ipv6_hdr(skb), | |
56 | (__force __u8)(~XT_DSCP_MASK), | |
57 | dinfo->dscp << XT_DSCP_SHIFT); | |
58 | } | |
59 | return XT_CONTINUE; | |
60 | } | |
61 | ||
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 | |
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 | |
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 | ||
150 | static int __init dscp_tg_init(void) | |
151 | { | |
152 | return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg)); | |
153 | } | |
154 | ||
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); |