ip6t_eui64.c

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/* Kernel module to match EUI64 address parameters. */

/* (C) 2001-2002 Andras Kis-Szabo <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <linux/if_ether.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>

MODULE_DESCRIPTION("Xtables: IPv6 EUI64 address match");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Andras Kis-Szabo <[email protected]>");

static bool
eui64_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
    unsigned char eui64[8];

    if (!(skb_mac_header(skb) >= skb->head &&
          skb_mac_header(skb) + ETH_HLEN <= skb->data) &&
        par->fragoff != 0) {
        par->hotdrop = true;
        return false;
    }

    memset(eui64, 0, sizeof(eui64));

    if (eth_hdr(skb)->h_proto == htons(ETH_P_IPV6)) {
        if (ipv6_hdr(skb)->version == 0x6) {
            memcpy(eui64, eth_hdr(skb)->h_source, 3);
            memcpy(eui64 + 5, eth_hdr(skb)->h_source + 3, 3);
            eui64[3] = 0xff;
            eui64[4] = 0xfe;
            eui64[0] ^= 0x02;

            if (!memcmp(ipv6_hdr(skb)->saddr.s6_addr + 8, eui64,
                    sizeof(eui64)))
                return true;
        }
    }

    return false;
}

static struct xt_match eui64_mt6_reg __read_mostly = {
    .name       = "eui64",
    .family     = NFPROTO_IPV6,
    .match      = eui64_mt6,
    .matchsize  = sizeof(int),
    .hooks      = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN) |
              (1 << NF_INET_FORWARD),
    .me     = THIS_MODULE,
};

static int __init eui64_mt6_init(void)
{
    return xt_register_match(&eui64_mt6_reg);
}

static void __exit eui64_mt6_exit(void)
{
    xt_unregister_match(&eui64_mt6_reg);
}

module_init(eui64_mt6_init);
module_exit(eui64_mt6_exit);