ip6t_eui64.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/* Kernel module to match EUI64 address parameters. */
 3
 4/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
 5 */
 6
 7#include <linux/module.h>
 8#include <linux/skbuff.h>
 9#include <linux/ipv6.h>
10#include <linux/if_ether.h>
11
12#include <linux/netfilter/x_tables.h>
13#include <linux/netfilter_ipv6/ip6_tables.h>
14
15MODULE_DESCRIPTION("Xtables: IPv6 EUI64 address match");
16MODULE_LICENSE("GPL");
17MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
18
19static bool
20eui64_mt6(const struct sk_buff *skb, struct xt_action_param *par)
21{
22	unsigned char eui64[8];
23
24	if (!(skb_mac_header(skb) >= skb->head &&
25	      skb_mac_header(skb) + ETH_HLEN <= skb->data)) {
26		par->hotdrop = true;
27		return false;
28	}
29
30	memset(eui64, 0, sizeof(eui64));
31
32	if (eth_hdr(skb)->h_proto == htons(ETH_P_IPV6)) {
33		if (ipv6_hdr(skb)->version == 0x6) {
34			memcpy(eui64, eth_hdr(skb)->h_source, 3);
35			memcpy(eui64 + 5, eth_hdr(skb)->h_source + 3, 3);
36			eui64[3] = 0xff;
37			eui64[4] = 0xfe;
38			eui64[0] ^= 0x02;
39
40			if (!memcmp(ipv6_hdr(skb)->saddr.s6_addr + 8, eui64,
41				    sizeof(eui64)))
42				return true;
43		}
44	}
45
46	return false;
47}
48
49static struct xt_match eui64_mt6_reg __read_mostly = {
50	.name		= "eui64",
51	.family		= NFPROTO_IPV6,
52	.match		= eui64_mt6,
53	.matchsize	= sizeof(int),
54	.hooks		= (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN) |
55			  (1 << NF_INET_FORWARD),
56	.me		= THIS_MODULE,
57};
58
59static int __init eui64_mt6_init(void)
60{
61	return xt_register_match(&eui64_mt6_reg);
62}
63
64static void __exit eui64_mt6_exit(void)
65{
66	xt_unregister_match(&eui64_mt6_reg);
67}
68
69module_init(eui64_mt6_init);
70module_exit(eui64_mt6_exit);