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(&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. */
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, &packet_mangler, repl, mangle_ops);
86	kfree(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, "mangle");
93}
94
95static void __net_exit ip6table_mangle_net_exit(struct net *net)
96{
97	ip6t_unregister_table_exit(net, "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(&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
129static 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
136module_init(ip6table_mangle_init);
137module_exit(ip6table_mangle_fini);
138