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 #include <linux/slab.h>
14 #include <net/ipv6.h>
15
16 MODULE_LICENSE("GPL");
17 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
18 MODULE_DESCRIPTION("ip6tables mangle table");
19
20 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
21 (1 << NF_INET_LOCAL_IN) | \
22 (1 << NF_INET_FORWARD) | \
23 (1 << NF_INET_LOCAL_OUT) | \
24 (1 << NF_INET_POST_ROUTING))
25
26 static int __net_init ip6table_mangle_table_init(struct net *net);
27
28 static const struct xt_table packet_mangler = {
29 .name = "mangle",
30 .valid_hooks = MANGLE_VALID_HOOKS,
31 .me = THIS_MODULE,
32 .af = NFPROTO_IPV6,
33 .priority = NF_IP6_PRI_MANGLE,
34 .table_init = ip6table_mangle_table_init,
35 };
36
37 static unsigned int
38 ip6t_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state)
39 {
40 unsigned int ret;
41 struct in6_addr saddr, daddr;
42 u_int8_t hop_limit;
43 u_int32_t flowlabel, mark;
44 int err;
45 #if 0
46 /* root is playing with raw sockets. */
47 if (skb->len < sizeof(struct iphdr) ||
48 ip_hdrlen(skb) < sizeof(struct iphdr)) {
49 net_warn_ratelimited("ip6t_hook: happy cracking\n");
50 return NF_ACCEPT;
51 }
52 #endif
53
54 /* save source/dest address, mark, hoplimit, flowlabel, priority, */
55 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
56 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
57 mark = skb->mark;
58 hop_limit = ipv6_hdr(skb)->hop_limit;
59
60 /* flowlabel and prio (includes version, which shouldn't change either */
61 flowlabel = *((u_int32_t *)ipv6_hdr(skb));
62
63 ret = ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
64
65 if (ret != NF_DROP && ret != NF_STOLEN &&
66 (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
67 !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
68 skb->mark != mark ||
69 ipv6_hdr(skb)->hop_limit != hop_limit ||
70 flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
71 err = ip6_route_me_harder(state->net, skb);
72 if (err < 0)
73 ret = NF_DROP_ERR(err);
74 }
75
76 return ret;
77 }
78
79 /* The work comes in here from netfilter.c. */
80 static unsigned int
81 ip6table_mangle_hook(void *priv, struct sk_buff *skb,
82 const struct nf_hook_state *state)
83 {
84 if (state->hook == NF_INET_LOCAL_OUT)
85 return ip6t_mangle_out(skb, state);
86 if (state->hook == NF_INET_POST_ROUTING)
87 return ip6t_do_table(skb, state,
88 state->net->ipv6.ip6table_mangle);
89 /* INPUT/FORWARD */
90 return ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
91 }
92
93 static struct nf_hook_ops *mangle_ops __read_mostly;
94 static int __net_init ip6table_mangle_table_init(struct net *net)
95 {
96 struct ip6t_replace *repl;
97 int ret;
98
99 if (net->ipv6.ip6table_mangle)
100 return 0;
101
102 repl = ip6t_alloc_initial_table(&packet_mangler);
103 if (repl == NULL)
104 return -ENOMEM;
105 ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops,
106 &net->ipv6.ip6table_mangle);
107 kfree(repl);
108 return ret;
109 }
110
111 static void __net_exit ip6table_mangle_net_exit(struct net *net)
112 {
113 if (!net->ipv6.ip6table_mangle)
114 return;
115
116 ip6t_unregister_table(net, net->ipv6.ip6table_mangle, mangle_ops);
117 net->ipv6.ip6table_mangle = NULL;
118 }
119
120 static struct pernet_operations ip6table_mangle_net_ops = {
121 .exit = ip6table_mangle_net_exit,
122 };
123
124 static int __init ip6table_mangle_init(void)
125 {
126 int ret;
127
128 mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook);
129 if (IS_ERR(mangle_ops))
130 return PTR_ERR(mangle_ops);
131
132 ret = register_pernet_subsys(&ip6table_mangle_net_ops);
133 if (ret < 0) {
134 kfree(mangle_ops);
135 return ret;
136 }
137
138 ret = ip6table_mangle_table_init(&init_net);
139 if (ret) {
140 unregister_pernet_subsys(&ip6table_mangle_net_ops);
141 kfree(mangle_ops);
142 }
143 return ret;
144 }
145
146 static void __exit ip6table_mangle_fini(void)
147 {
148 unregister_pernet_subsys(&ip6table_mangle_net_ops);
149 kfree(mangle_ops);
150 }
151
152 module_init(ip6table_mangle_init);
153 module_exit(ip6table_mangle_fini);
154
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