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 const struct xt_table packet_mangler = {
27 .name = "mangle",
28 .valid_hooks = MANGLE_VALID_HOOKS,
29 .me = THIS_MODULE,
30 .af = NFPROTO_IPV6,
31 .priority = NF_IP6_PRI_MANGLE,
32 };
33
34 static unsigned int
ip6t_mangle_out(struct sk_buff * skb,const struct net_device * out)35 ip6t_mangle_out(struct sk_buff *skb, const struct net_device *out)
36 {
37 unsigned int ret;
38 struct in6_addr saddr, daddr;
39 u_int8_t hop_limit;
40 u_int32_t flowlabel, mark;
41 int err;
42 #if 0
43 /* root is playing with raw sockets. */
44 if (skb->len < sizeof(struct iphdr) ||
45 ip_hdrlen(skb) < sizeof(struct iphdr)) {
46 net_warn_ratelimited("ip6t_hook: happy cracking\n");
47 return NF_ACCEPT;
48 }
49 #endif
50
51 /* save source/dest address, mark, hoplimit, flowlabel, priority, */
52 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
53 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
54 mark = skb->mark;
55 hop_limit = ipv6_hdr(skb)->hop_limit;
56
57 /* flowlabel and prio (includes version, which shouldn't change either */
58 flowlabel = *((u_int32_t *)ipv6_hdr(skb));
59
60 ret = ip6t_do_table(skb, NF_INET_LOCAL_OUT, NULL, out,
61 dev_net(out)->ipv6.ip6table_mangle);
62
63 if (ret != NF_DROP && ret != NF_STOLEN &&
64 (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
65 !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
66 skb->mark != mark ||
67 ipv6_hdr(skb)->hop_limit != hop_limit ||
68 flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
69 err = ip6_route_me_harder(skb);
70 if (err < 0)
71 ret = NF_DROP_ERR(err);
72 }
73
74 return ret;
75 }
76
77 /* The work comes in here from netfilter.c. */
78 static unsigned int
ip6table_mangle_hook(unsigned int hook,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))79 ip6table_mangle_hook(unsigned int hook, struct sk_buff *skb,
80 const struct net_device *in, const struct net_device *out,
81 int (*okfn)(struct sk_buff *))
82 {
83 if (hook == NF_INET_LOCAL_OUT)
84 return ip6t_mangle_out(skb, out);
85 if (hook == NF_INET_POST_ROUTING)
86 return ip6t_do_table(skb, hook, in, out,
87 dev_net(out)->ipv6.ip6table_mangle);
88 /* INPUT/FORWARD */
89 return ip6t_do_table(skb, hook, in, out,
90 dev_net(in)->ipv6.ip6table_mangle);
91 }
92
93 static struct nf_hook_ops *mangle_ops __read_mostly;
ip6table_mangle_net_init(struct net * net)94 static int __net_init ip6table_mangle_net_init(struct net *net)
95 {
96 struct ip6t_replace *repl;
97
98 repl = ip6t_alloc_initial_table(&packet_mangler);
99 if (repl == NULL)
100 return -ENOMEM;
101 net->ipv6.ip6table_mangle =
102 ip6t_register_table(net, &packet_mangler, repl);
103 kfree(repl);
104 return PTR_RET(net->ipv6.ip6table_mangle);
105 }
106
ip6table_mangle_net_exit(struct net * net)107 static void __net_exit ip6table_mangle_net_exit(struct net *net)
108 {
109 ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
110 }
111
112 static struct pernet_operations ip6table_mangle_net_ops = {
113 .init = ip6table_mangle_net_init,
114 .exit = ip6table_mangle_net_exit,
115 };
116
ip6table_mangle_init(void)117 static int __init ip6table_mangle_init(void)
118 {
119 int ret;
120
121 ret = register_pernet_subsys(&ip6table_mangle_net_ops);
122 if (ret < 0)
123 return ret;
124
125 /* Register hooks */
126 mangle_ops = xt_hook_link(&packet_mangler, ip6table_mangle_hook);
127 if (IS_ERR(mangle_ops)) {
128 ret = PTR_ERR(mangle_ops);
129 goto cleanup_table;
130 }
131
132 return ret;
133
134 cleanup_table:
135 unregister_pernet_subsys(&ip6table_mangle_net_ops);
136 return ret;
137 }
138
ip6table_mangle_fini(void)139 static void __exit ip6table_mangle_fini(void)
140 {
141 xt_hook_unlink(&packet_mangler, mangle_ops);
142 unregister_pernet_subsys(&ip6table_mangle_net_ops);
143 }
144
145 module_init(ip6table_mangle_init);
146 module_exit(ip6table_mangle_fini);
147