net/ipv6/netfilter/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
  15 MODULE_DESCRIPTION("Xtables: IPv6 EUI64 address match");
  16 MODULE_LICENSE("GPL");
  17 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  18
  19 static bool
  20 eui64_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->fragoff != 0) {
  27                 par->hotdrop = true;
  28                 return false;
  29         }
  30
  31         memset(eui64, 0, sizeof(eui64));
  32
  33         if (eth_hdr(skb)->h_proto == htons(ETH_P_IPV6)) {
  34                 if (ipv6_hdr(skb)->version == 0x6) {
  35                         memcpy(eui64, eth_hdr(skb)->h_source, 3);
  36                         memcpy(eui64 + 5, eth_hdr(skb)->h_source + 3, 3);
  37                         eui64[3] = 0xff;
  38                         eui64[4] = 0xfe;
  39                         eui64[0] ^= 0x02;
  40
  41                         if (!memcmp(ipv6_hdr(skb)->saddr.s6_addr + 8, eui64,
  42                                     sizeof(eui64)))
  43                                 return true;
  44                 }
  45         }
  46
  47         return false;
  48 }
  49
  50 static struct xt_match eui64_mt6_reg __read_mostly = {
  51         .name           = "eui64",
  52         .family         = NFPROTO_IPV6,
  53         .match          = eui64_mt6,
  54         .matchsize      = sizeof(int),
  55         .hooks          = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN) |
  56                           (1 << NF_INET_FORWARD),
  57         .me             = THIS_MODULE,
  58 };
  59
  60 static int __init eui64_mt6_init(void)
  61 {
  62         return xt_register_match(&eui64_mt6_reg);
  63 }
  64
  65 static void __exit eui64_mt6_exit(void)
  66 {
  67         xt_unregister_match(&eui64_mt6_reg);
  68 }
  69
  70 module_init(eui64_mt6_init);
  71 module_exit(eui64_mt6_exit);