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
15 MODULE_LICENSE("GPL");
16 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
17 MODULE_DESCRIPTION("ip6tables mangle table");
18
19 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
20 (1 << NF_INET_LOCAL_IN) | \
21 (1 << NF_INET_FORWARD) | \
22 (1 << NF_INET_LOCAL_OUT) | \
23 (1 << NF_INET_POST_ROUTING))
24
25 static const struct xt_table packet_mangler = {
26 .name = "mangle",
27 .valid_hooks = MANGLE_VALID_HOOKS,
28 .me = THIS_MODULE,
29 .af = NFPROTO_IPV6,
30 .priority = NF_IP6_PRI_MANGLE,
31 };
32
33 static unsigned int
ip6t_mangle_out(struct sk_buff * skb,const struct net_device * out)34 ip6t_mangle_out(struct sk_buff *skb, const struct net_device *out)
35 {
36 unsigned int ret;
37 struct in6_addr saddr, daddr;
38 u_int8_t hop_limit;
39 u_int32_t flowlabel, mark;
40
41 #if 0
42 /* root is playing with raw sockets. */
43 if (skb->len < sizeof(struct iphdr) ||
44 ip_hdrlen(skb) < sizeof(struct iphdr)) {
45 if (net_ratelimit())
46 pr_warning("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 (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr)) ||
65 memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr)) ||
66 skb->mark != mark ||
67 ipv6_hdr(skb)->hop_limit != hop_limit ||
68 flowlabel != *((u_int32_t *)ipv6_hdr(skb))))
69 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
70
71 return ret;
72 }
73
74 /* The work comes in here from netfilter.c. */
75 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 *))76 ip6table_mangle_hook(unsigned int hook, struct sk_buff *skb,
77 const struct net_device *in, const struct net_device *out,
78 int (*okfn)(struct sk_buff *))
79 {
80 if (hook == NF_INET_LOCAL_OUT)
81 return ip6t_mangle_out(skb, out);
82 if (hook == NF_INET_POST_ROUTING)
83 return ip6t_do_table(skb, hook, in, out,
84 dev_net(out)->ipv6.ip6table_mangle);
85 /* INPUT/FORWARD */
86 return ip6t_do_table(skb, hook, in, out,
87 dev_net(in)->ipv6.ip6table_mangle);
88 }
89
90 static struct nf_hook_ops *mangle_ops __read_mostly;
ip6table_mangle_net_init(struct net * net)91 static int __net_init ip6table_mangle_net_init(struct net *net)
92 {
93 struct ip6t_replace *repl;
94
95 repl = ip6t_alloc_initial_table(&packet_mangler);
96 if (repl == NULL)
97 return -ENOMEM;
98 net->ipv6.ip6table_mangle =
99 ip6t_register_table(net, &packet_mangler, repl);
100 kfree(repl);
101 if (IS_ERR(net->ipv6.ip6table_mangle))
102 return PTR_ERR(net->ipv6.ip6table_mangle);
103 return 0;
104 }
105
ip6table_mangle_net_exit(struct net * net)106 static void __net_exit ip6table_mangle_net_exit(struct net *net)
107 {
108 ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
109 }
110
111 static struct pernet_operations ip6table_mangle_net_ops = {
112 .init = ip6table_mangle_net_init,
113 .exit = ip6table_mangle_net_exit,
114 };
115
ip6table_mangle_init(void)116 static int __init ip6table_mangle_init(void)
117 {
118 int ret;
119
120 ret = register_pernet_subsys(&ip6table_mangle_net_ops);
121 if (ret < 0)
122 return ret;
123
124 /* Register hooks */
125 mangle_ops = xt_hook_link(&packet_mangler, ip6table_mangle_hook);
126 if (IS_ERR(mangle_ops)) {
127 ret = PTR_ERR(mangle_ops);
128 goto cleanup_table;
129 }
130
131 return ret;
132
133 cleanup_table:
134 unregister_pernet_subsys(&ip6table_mangle_net_ops);
135 return ret;
136 }
137
ip6table_mangle_fini(void)138 static void __exit ip6table_mangle_fini(void)
139 {
140 xt_hook_unlink(&packet_mangler, mangle_ops);
141 unregister_pernet_subsys(&ip6table_mangle_net_ops);
142 }
143
144 module_init(ip6table_mangle_init);
145 module_exit(ip6table_mangle_fini);
146