1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * IPv6 packet mangling table, a port of the IPv4 mangle table to IPv6
4 *
5 * Copyright (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
6 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
7 */
8 #include <linux/module.h>
9 #include <linux/netfilter_ipv6/ip6_tables.h>
10 #include <linux/slab.h>
11 #include <net/ipv6.h>
12
13 MODULE_LICENSE("GPL");
14 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
15 MODULE_DESCRIPTION("ip6tables mangle table");
16
17 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
18 (1 << NF_INET_LOCAL_IN) | \
19 (1 << NF_INET_FORWARD) | \
20 (1 << NF_INET_LOCAL_OUT) | \
21 (1 << NF_INET_POST_ROUTING))
22
23 static const struct xt_table packet_mangler = {
24 .name = "mangle",
25 .valid_hooks = MANGLE_VALID_HOOKS,
26 .me = THIS_MODULE,
27 .af = NFPROTO_IPV6,
28 .priority = NF_IP6_PRI_MANGLE,
29 };
30
31 static unsigned int
32 ip6t_mangle_out(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
33 {
34 struct in6_addr saddr, daddr;
35 unsigned int ret, verdict;
36 u32 flowlabel, mark;
37 u8 hop_limit;
38 int err;
39
40 /* save source/dest address, mark, hoplimit, flowlabel, priority, */
41 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
42 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
43 mark = skb->mark;
44 hop_limit = ipv6_hdr(skb)->hop_limit;
45
46 /* flowlabel and prio (includes version, which shouldn't change either */
47 flowlabel = *((u_int32_t *)ipv6_hdr(skb));
48
49 ret = ip6t_do_table(priv, skb, state);
50 verdict = ret & NF_VERDICT_MASK;
51
52 if (verdict != NF_DROP && verdict != NF_STOLEN &&
53 (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
54 !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
55 skb->mark != mark ||
56 ipv6_hdr(skb)->hop_limit != hop_limit ||
57 flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
58 err = ip6_route_me_harder(state->net, state->sk, skb);
59 if (err < 0)
60 ret = NF_DROP_ERR(err);
61 }
62
63 return ret;
64 }
65
66 /* The work comes in here from netfilter.c. */
67 static unsigned int
68 ip6table_mangle_hook(void *priv, struct sk_buff *skb,
69 const struct nf_hook_state *state)
70 {
71 if (state->hook == NF_INET_LOCAL_OUT)
72 return ip6t_mangle_out(priv, skb, state);
73 return ip6t_do_table(priv, skb, state);
74 }
75
76 static struct nf_hook_ops *mangle_ops __read_mostly;
77 static int ip6table_mangle_table_init(struct net *net)
78 {
79 struct ip6t_replace *repl;
80 int ret;
81
82 repl = ip6t_alloc_initial_table(&packet_mangler);
83 if (repl == NULL)
84 return -ENOMEM;
85 ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops);
86 kfree(repl);
87 return ret;
88 }
89
90 static void __net_exit ip6table_mangle_net_pre_exit(struct net *net)
91 {
92 ip6t_unregister_table_pre_exit(net, "mangle");
93 }
94
95 static void __net_exit ip6table_mangle_net_exit(struct net *net)
96 {
97 ip6t_unregister_table_exit(net, "mangle");
98 }
99
100 static struct pernet_operations ip6table_mangle_net_ops = {
101 .pre_exit = ip6table_mangle_net_pre_exit,
102 .exit = ip6table_mangle_net_exit,
103 };
104
105 static int __init ip6table_mangle_init(void)
106 {
107 int ret = xt_register_template(&packet_mangler,
108 ip6table_mangle_table_init);
109
110 if (ret < 0)
111 return ret;
112
113 mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook);
114 if (IS_ERR(mangle_ops)) {
115 xt_unregister_template(&packet_mangler);
116 return PTR_ERR(mangle_ops);
117 }
118
119 ret = register_pernet_subsys(&ip6table_mangle_net_ops);
120 if (ret < 0) {
121 xt_unregister_template(&packet_mangler);
122 kfree(mangle_ops);
123 return ret;
124 }
125
126 return ret;
127 }
128
129 static void __exit ip6table_mangle_fini(void)
130 {
131 unregister_pernet_subsys(&ip6table_mangle_net_ops);
132 xt_unregister_template(&packet_mangler);
133 kfree(mangle_ops);
134 }
135
136 module_init(ip6table_mangle_init);
137 module_exit(ip6table_mangle_fini);
138
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