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("Xtables: IPv6 Hop Limit field match");
  20 MODULE_LICENSE("GPL");
  21
  22 static bool
  23 hl_mt6(const struct sk_buff *skb, const struct net_device *in,
  24        const struct net_device *out, const struct xt_match *match,
  25        const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop)
  26 {
  27         const struct ip6t_hl_info *info = matchinfo;
  28         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
  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 false;
  47         }
  48
  49         return false;
  50 }
  51
  52 static struct xt_match hl_mt6_reg __read_mostly = {
  53         .name           = "hl",
  54         .family         = AF_INET6,
  55         .match          = hl_mt6,
  56         .matchsize      = sizeof(struct ip6t_hl_info),
  57         .me             = THIS_MODULE,
  58 };
  59
  60 static int __init hl_mt6_init(void)
  61 {
  62         return xt_register_match(&hl_mt6_reg);
  63 }
  64
  65 static void __exit hl_mt6_exit(void)
  66 {
  67         xt_unregister_match(&hl_mt6_reg);
  68 }
  69
  70 module_init(hl_mt6_init);
  71 module_exit(hl_mt6_exit);