5023ac52ffec0e2ad0b5b99f323a536c7eced346
[linux-2.6.git] / net / ipv6 / netfilter / ip6table_mangle.c
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 const 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 const struct xt_table packet_mangler = {
61         .name           = "mangle",
62         .valid_hooks    = MANGLE_VALID_HOOKS,
63         .me             = THIS_MODULE,
64         .af             = NFPROTO_IPV6,
65         .priority       = NF_IP6_PRI_MANGLE,
66 };
67
68 static unsigned int
69 ip6t_local_out_hook(unsigned int hook,
70                    struct sk_buff *skb,
71                    const struct net_device *out,
72                    int (*okfn)(struct sk_buff *))
73 {
74
75         unsigned int ret;
76         struct in6_addr saddr, daddr;
77         u_int8_t hop_limit;
78         u_int32_t flowlabel, mark;
79
80 #if 0
81         /* root is playing with raw sockets. */
82         if (skb->len < sizeof(struct iphdr) ||
83             ip_hdrlen(skb) < sizeof(struct iphdr)) {
84                 if (net_ratelimit())
85                         printk("ip6t_hook: happy cracking.\n");
86                 return NF_ACCEPT;
87         }
88 #endif
89
90         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
91         memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
92         memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
93         mark = skb->mark;
94         hop_limit = ipv6_hdr(skb)->hop_limit;
95
96         /* flowlabel and prio (includes version, which shouldn't change either */
97         flowlabel = *((u_int32_t *)ipv6_hdr(skb));
98
99         ret = ip6t_do_table(skb, hook, NULL, out,
100                             dev_net(out)->ipv6.ip6table_mangle);
101
102         if (ret != NF_DROP && ret != NF_STOLEN &&
103             (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr)) ||
104              memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr)) ||
105              skb->mark != mark ||
106              ipv6_hdr(skb)->hop_limit != hop_limit))
107                 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
108
109         return ret;
110 }
111
112 /* The work comes in here from netfilter.c. */
113 static unsigned int
114 ip6table_mangle_hook(unsigned int hook, struct sk_buff *skb,
115                      const struct net_device *in, const struct net_device *out,
116                      int (*okfn)(struct sk_buff *))
117 {
118         if (hook == NF_INET_LOCAL_OUT)
119                 return ip6t_local_out_hook(hook, skb, out, okfn);
120
121         /* INPUT/FORWARD */
122         return ip6t_do_table(skb, hook, in, out,
123                              dev_net(in)->ipv6.ip6table_mangle);
124 }
125
126 static struct nf_hook_ops *mangle_ops __read_mostly;
127 static int __net_init ip6table_mangle_net_init(struct net *net)
128 {
129         /* Register table */
130         net->ipv6.ip6table_mangle =
131                 ip6t_register_table(net, &packet_mangler, &initial_table.repl);
132         if (IS_ERR(net->ipv6.ip6table_mangle))
133                 return PTR_ERR(net->ipv6.ip6table_mangle);
134         return 0;
135 }
136
137 static void __net_exit ip6table_mangle_net_exit(struct net *net)
138 {
139         ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
140 }
141
142 static struct pernet_operations ip6table_mangle_net_ops = {
143         .init = ip6table_mangle_net_init,
144         .exit = ip6table_mangle_net_exit,
145 };
146
147 static int __init ip6table_mangle_init(void)
148 {
149         int ret;
150
151         ret = register_pernet_subsys(&ip6table_mangle_net_ops);
152         if (ret < 0)
153                 return ret;
154
155         /* Register hooks */
156         mangle_ops = xt_hook_link(&packet_mangler, ip6table_mangle_hook);
157         if (IS_ERR(mangle_ops)) {
158                 ret = PTR_ERR(mangle_ops);
159                 goto cleanup_table;
160         }
161
162         return ret;
163
164  cleanup_table:
165         unregister_pernet_subsys(&ip6table_mangle_net_ops);
166         return ret;
167 }
168
169 static void __exit ip6table_mangle_fini(void)
170 {
171         xt_hook_unlink(&packet_mangler, mangle_ops);
172         unregister_pernet_subsys(&ip6table_mangle_net_ops);
173 }
174
175 module_init(ip6table_mangle_init);
176 module_exit(ip6table_mangle_fini);