1 /*
2 * IPv6 packet mangling table, a port of the IPv4 mangle table to IPv6
3 *
4 * Copyright (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
5 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11 #include <linux/module.h>
12 #include <linux/netfilter_ipv6/ip6_tables.h>
13
14 MODULE_LICENSE("GPL");
15 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
16 MODULE_DESCRIPTION("ip6tables mangle table");
17
18 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
19 (1 << NF_INET_LOCAL_IN) | \
20 (1 << NF_INET_FORWARD) | \
21 (1 << NF_INET_LOCAL_OUT) | \
22 (1 << NF_INET_POST_ROUTING))
23
24 static struct
25 {
26 struct ip6t_replace repl;
27 struct ip6t_standard entries[5];
28 struct ip6t_error term;
29 } initial_table __net_initdata = {
30 .repl = {
31 .name = "mangle",
32 .valid_hooks = MANGLE_VALID_HOOKS,
33 .num_entries = 6,
34 .size = sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
35 .hook_entry = {
36 [NF_INET_PRE_ROUTING] = 0,
37 [NF_INET_LOCAL_IN] = sizeof(struct ip6t_standard),
38 [NF_INET_FORWARD] = sizeof(struct ip6t_standard) * 2,
39 [NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard) * 3,
40 [NF_INET_POST_ROUTING] = sizeof(struct ip6t_standard) * 4,
41 },
42 .underflow = {
43 [NF_INET_PRE_ROUTING] = 0,
44 [NF_INET_LOCAL_IN] = sizeof(struct ip6t_standard),
45 [NF_INET_FORWARD] = sizeof(struct ip6t_standard) * 2,
46 [NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard) * 3,
47 [NF_INET_POST_ROUTING] = sizeof(struct ip6t_standard) * 4,
48 },
49 },
50 .entries = {
51 IP6T_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
52 IP6T_STANDARD_INIT(NF_ACCEPT), /* LOCAL_IN */
53 IP6T_STANDARD_INIT(NF_ACCEPT), /* FORWARD */
54 IP6T_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
55 IP6T_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
56 },
57 .term = IP6T_ERROR_INIT, /* ERROR */
58 };
59
60 static struct xt_table packet_mangler = {
61 .name = "mangle",
62 .valid_hooks = MANGLE_VALID_HOOKS,
63 .lock = RW_LOCK_UNLOCKED,
64 .me = THIS_MODULE,
65 .af = AF_INET6,
66 };
67
68 /* The work comes in here from netfilter.c. */
69 static unsigned int
70 ip6t_route_hook(unsigned int hook,
71 struct sk_buff *skb,
72 const struct net_device *in,
73 const struct net_device *out,
74 int (*okfn)(struct sk_buff *))
75 {
76 return ip6t_do_table(skb, hook, in, out, init_net.ipv6.ip6table_mangle);
77 }
78
79 static unsigned int
80 ip6t_local_hook(unsigned int hook,
81 struct sk_buff *skb,
82 const struct net_device *in,
83 const struct net_device *out,
84 int (*okfn)(struct sk_buff *))
85 {
86
87 unsigned int ret;
88 struct in6_addr saddr, daddr;
89 u_int8_t hop_limit;
90 u_int32_t flowlabel, mark;
91
92 #if 0
93 /* root is playing with raw sockets. */
94 if (skb->len < sizeof(struct iphdr)
95 || ip_hdrlen(skb) < sizeof(struct iphdr)) {
96 if (net_ratelimit())
97 printk("ip6t_hook: happy cracking.\n");
98 return NF_ACCEPT;
99 }
100 #endif
101
102 /* save source/dest address, mark, hoplimit, flowlabel, priority, */
103 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
104 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
105 mark = skb->mark;
106 hop_limit = ipv6_hdr(skb)->hop_limit;
107
108 /* flowlabel and prio (includes version, which shouldn't change either */
109 flowlabel = *((u_int32_t *)ipv6_hdr(skb));
110
111 ret = ip6t_do_table(skb, hook, in, out, init_net.ipv6.ip6table_mangle);
112
113 if (ret != NF_DROP && ret != NF_STOLEN
114 && (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr))
115 || memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr))
116 || skb->mark != mark
117 || ipv6_hdr(skb)->hop_limit != hop_limit))
118 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
119
120 return ret;
121 }
122
123 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
124 {
125 .hook = ip6t_route_hook,
126 .owner = THIS_MODULE,
127 .pf = PF_INET6,
128 .hooknum = NF_INET_PRE_ROUTING,
129 .priority = NF_IP6_PRI_MANGLE,
130 },
131 {
132 .hook = ip6t_local_hook,
133 .owner = THIS_MODULE,
134 .pf = PF_INET6,
135 .hooknum = NF_INET_LOCAL_IN,
136 .priority = NF_IP6_PRI_MANGLE,
137 },
138 {
139 .hook = ip6t_route_hook,
140 .owner = THIS_MODULE,
141 .pf = PF_INET6,
142 .hooknum = NF_INET_FORWARD,
143 .priority = NF_IP6_PRI_MANGLE,
144 },
145 {
146 .hook = ip6t_local_hook,
147 .owner = THIS_MODULE,
148 .pf = PF_INET6,
149 .hooknum = NF_INET_LOCAL_OUT,
150 .priority = NF_IP6_PRI_MANGLE,
151 },
152 {
153 .hook = ip6t_route_hook,
154 .owner = THIS_MODULE,
155 .pf = PF_INET6,
156 .hooknum = NF_INET_POST_ROUTING,
157 .priority = NF_IP6_PRI_MANGLE,
158 },
159 };
160
161 static int __net_init ip6table_mangle_net_init(struct net *net)
162 {
163 /* Register table */
164 net->ipv6.ip6table_mangle =
165 ip6t_register_table(net, &packet_mangler, &initial_table.repl);
166 if (IS_ERR(net->ipv6.ip6table_mangle))
167 return PTR_ERR(net->ipv6.ip6table_mangle);
168 return 0;
169 }
170
171 static void __net_exit ip6table_mangle_net_exit(struct net *net)
172 {
173 ip6t_unregister_table(net->ipv6.ip6table_mangle);
174 }
175
176 static struct pernet_operations ip6table_mangle_net_ops = {
177 .init = ip6table_mangle_net_init,
178 .exit = ip6table_mangle_net_exit,
179 };
180
181 static int __init ip6table_mangle_init(void)
182 {
183 int ret;
184
185 ret = register_pernet_subsys(&ip6table_mangle_net_ops);
186 if (ret < 0)
187 return ret;
188
189 /* Register hooks */
190 ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
191 if (ret < 0)
192 goto cleanup_table;
193
194 return ret;
195
196 cleanup_table:
197 unregister_pernet_subsys(&ip6table_mangle_net_ops);
198 return ret;
199 }
200
201 static void __exit ip6table_mangle_fini(void)
202 {
203 nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
204 unregister_pernet_subsys(&ip6table_mangle_net_ops);
205 }
206
207 module_init(ip6table_mangle_init);
208 module_exit(ip6table_mangle_fini);
209
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