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 int __net_init ip6table_mangle_table_init(struct net *net);
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 .table_init = ip6table_mangle_table_init,
32 };
33
34 static unsigned int
ip6t_mangle_out(struct sk_buff * skb,const struct nf_hook_state * state)35 ip6t_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state)
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
43 /* save source/dest address, mark, hoplimit, flowlabel, priority, */
44 memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
45 memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
46 mark = skb->mark;
47 hop_limit = ipv6_hdr(skb)->hop_limit;
48
49 /* flowlabel and prio (includes version, which shouldn't change either */
50 flowlabel = *((u_int32_t *)ipv6_hdr(skb));
51
52 ret = ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
53
54 if (ret != NF_DROP && ret != NF_STOLEN &&
55 (!ipv6_addr_equal(&ipv6_hdr(skb)->saddr, &saddr) ||
56 !ipv6_addr_equal(&ipv6_hdr(skb)->daddr, &daddr) ||
57 skb->mark != mark ||
58 ipv6_hdr(skb)->hop_limit != hop_limit ||
59 flowlabel != *((u_int32_t *)ipv6_hdr(skb)))) {
60 err = ip6_route_me_harder(state->net, state->sk, skb);
61 if (err < 0)
62 ret = NF_DROP_ERR(err);
63 }
64
65 return ret;
66 }
67
68 /* The work comes in here from netfilter.c. */
69 static unsigned int
ip6table_mangle_hook(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)70 ip6table_mangle_hook(void *priv, struct sk_buff *skb,
71 const struct nf_hook_state *state)
72 {
73 if (state->hook == NF_INET_LOCAL_OUT)
74 return ip6t_mangle_out(skb, state);
75 return ip6t_do_table(skb, state, state->net->ipv6.ip6table_mangle);
76 }
77
78 static struct nf_hook_ops *mangle_ops __read_mostly;
ip6table_mangle_table_init(struct net * net)79 static int __net_init ip6table_mangle_table_init(struct net *net)
80 {
81 struct ip6t_replace *repl;
82 int ret;
83
84 if (net->ipv6.ip6table_mangle)
85 return 0;
86
87 repl = ip6t_alloc_initial_table(&packet_mangler);
88 if (repl == NULL)
89 return -ENOMEM;
90 ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops,
91 &net->ipv6.ip6table_mangle);
92 kfree(repl);
93 return ret;
94 }
95
ip6table_mangle_net_pre_exit(struct net * net)96 static void __net_exit ip6table_mangle_net_pre_exit(struct net *net)
97 {
98 if (net->ipv6.ip6table_mangle)
99 ip6t_unregister_table_pre_exit(net, net->ipv6.ip6table_mangle,
100 mangle_ops);
101 }
102
ip6table_mangle_net_exit(struct net * net)103 static void __net_exit ip6table_mangle_net_exit(struct net *net)
104 {
105 if (!net->ipv6.ip6table_mangle)
106 return;
107
108 ip6t_unregister_table_exit(net, net->ipv6.ip6table_mangle);
109 net->ipv6.ip6table_mangle = NULL;
110 }
111
112 static struct pernet_operations ip6table_mangle_net_ops = {
113 .pre_exit = ip6table_mangle_net_pre_exit,
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 mangle_ops = xt_hook_ops_alloc(&packet_mangler, ip6table_mangle_hook);
122 if (IS_ERR(mangle_ops))
123 return PTR_ERR(mangle_ops);
124
125 ret = register_pernet_subsys(&ip6table_mangle_net_ops);
126 if (ret < 0) {
127 kfree(mangle_ops);
128 return ret;
129 }
130
131 ret = ip6table_mangle_table_init(&init_net);
132 if (ret) {
133 unregister_pernet_subsys(&ip6table_mangle_net_ops);
134 kfree(mangle_ops);
135 }
136 return ret;
137 }
138
ip6table_mangle_fini(void)139 static void __exit ip6table_mangle_fini(void)
140 {
141 unregister_pernet_subsys(&ip6table_mangle_net_ops);
142 kfree(mangle_ops);
143 }
144
145 module_init(ip6table_mangle_init);
146 module_exit(ip6table_mangle_fini);
147