net/ipv6/netfilter/ip6t_hl.c

   1 /* Hop Limit matching module */
   2
   3 /* (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
   4  * Based on HW's ttl module
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/ipv6.h>
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14
  15 #include <linux/netfilter_ipv6/ip6t_hl.h>
  16 #include <linux/netfilter/x_tables.h>
  17
  18 MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
  19 MODULE_DESCRIPTION("IP tables Hop Limit matching module");
  20 MODULE_LICENSE("GPL");
  21
  22 static int match(const struct sk_buff *skb,
  23                  const struct net_device *in, const struct net_device *out,
  24                  const struct xt_match *match, const void *matchinfo,
  25                  int offset, unsigned int protoff, int *hotdrop)
  26 {
  27         const struct ip6t_hl_info *info = matchinfo;
  28         const struct ipv6hdr *ip6h = skb->nh.ipv6h;
  29
  30         switch (info->mode) {
  31                 case IP6T_HL_EQ:
  32                         return (ip6h->hop_limit == info->hop_limit);
  33                         break;
  34                 case IP6T_HL_NE:
  35                         return (!(ip6h->hop_limit == info->hop_limit));
  36                         break;
  37                 case IP6T_HL_LT:
  38                         return (ip6h->hop_limit < info->hop_limit);
  39                         break;
  40                 case IP6T_HL_GT:
  41                         return (ip6h->hop_limit > info->hop_limit);
  42                         break;
  43                 default:
  44                         printk(KERN_WARNING "ip6t_hl: unknown mode %d\n",
  45                                 info->mode);
  46                         return 0;
  47         }
  48
  49         return 0;
  50 }
  51
  52 static struct xt_match hl_match = {
  53         .name           = "hl",
  54         .family         = AF_INET6,
  55         .match          = match,
  56         .matchsize      = sizeof(struct ip6t_hl_info),
  57         .me             = THIS_MODULE,
  58 };
  59
  60 static int __init ip6t_hl_init(void)
  61 {
  62         return xt_register_match(&hl_match);
  63 }
  64
  65 static void __exit ip6t_hl_fini(void)
  66 {
  67         xt_unregister_match(&hl_match);
  68 }
  69
  70 module_init(ip6t_hl_init);
  71 module_exit(ip6t_hl_fini);