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11#include <linux/module.h>
12#include <linux/netfilter_ipv6/ip6_tables.h>
13#include <linux/slab.h>
14#include <net/ipv6.h>
15
16MODULE_LICENSE("GPL");
17MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
18MODULE_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
26static 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
34static unsigned int
35ip6t_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
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
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
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
78static unsigned int
79ip6table_mangle_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
80 const struct net_device *in, const struct net_device *out,
81 int (*okfn)(struct sk_buff *))
82{
83 if (ops->hooknum == NF_INET_LOCAL_OUT)
84 return ip6t_mangle_out(skb, out);
85 if (ops->hooknum == NF_INET_POST_ROUTING)
86 return ip6t_do_table(skb, ops->hooknum, in, out,
87 dev_net(out)->ipv6.ip6table_mangle);
88
89 return ip6t_do_table(skb, ops->hooknum, in, out,
90 dev_net(in)->ipv6.ip6table_mangle);
91}
92
93static struct nf_hook_ops *mangle_ops __read_mostly;
94static 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_ERR_OR_ZERO(net->ipv6.ip6table_mangle);
105}
106
107static void __net_exit ip6table_mangle_net_exit(struct net *net)
108{
109 ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
110}
111
112static struct pernet_operations ip6table_mangle_net_ops = {
113 .init = ip6table_mangle_net_init,
114 .exit = ip6table_mangle_net_exit,
115};
116
117static 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
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
139static 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
145module_init(ip6table_mangle_init);
146module_exit(ip6table_mangle_fini);
147