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
13MODULE_LICENSE("GPL");
14MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
15MODULE_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
23static 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
31static unsigned int
32ip6t_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(a1: &ipv6_hdr(skb)->saddr, a2: &saddr) ||
54 !ipv6_addr_equal(a1: &ipv6_hdr(skb)->daddr, a2: &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(net: state->net, sk: 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. */
67static unsigned int
68ip6table_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
76static struct nf_hook_ops *mangle_ops __read_mostly;
77static 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, table: &packet_mangler, repl, ops: mangle_ops);
86 kfree(objp: repl);
87 return ret;
88}
89
90static void __net_exit ip6table_mangle_net_pre_exit(struct net *net)
91{
92 ip6t_unregister_table_pre_exit(net, name: "mangle");
93}
94
95static void __net_exit ip6table_mangle_net_exit(struct net *net)
96{
97 ip6t_unregister_table_exit(net, name: "mangle");
98}
99
100static struct pernet_operations ip6table_mangle_net_ops = {
101 .pre_exit = ip6table_mangle_net_pre_exit,
102 .exit = ip6table_mangle_net_exit,
103};
104
105static int __init ip6table_mangle_init(void)
106{
107 int ret = xt_register_template(t: &packet_mangler,
108 table_init: 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(ptr: mangle_ops)) {
115 xt_unregister_template(t: &packet_mangler);
116 return PTR_ERR(ptr: mangle_ops);
117 }
118
119 ret = register_pernet_subsys(&ip6table_mangle_net_ops);
120 if (ret < 0) {
121 xt_unregister_template(t: &packet_mangler);
122 kfree(objp: mangle_ops);
123 return ret;
124 }
125
126 return ret;
127}
128
129static void __exit ip6table_mangle_fini(void)
130{
131 unregister_pernet_subsys(&ip6table_mangle_net_ops);
132 xt_unregister_template(t: &packet_mangler);
133 kfree(objp: mangle_ops);
134}
135
136module_init(ip6table_mangle_init);
137module_exit(ip6table_mangle_fini);
138

source code of linux/net/ipv6/netfilter/ip6table_mangle.c