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/module.h>
  12 #include <linux/skbuff.h>
  13
  14 #include <linux/netfilter_ipv6/ip6t_hl.h>
  15 #include <linux/netfilter_ipv6/ip6_tables.h>
  16
  17 MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
  18 MODULE_DESCRIPTION("IP tables Hop Limit matching module");
  19 MODULE_LICENSE("GPL");
  20
  21 static int match(const struct sk_buff *skb, const struct net_device *in,
  22                  const struct net_device *out, const void *matchinfo,
  23                  int offset, unsigned int protoff,
  24                  int *hotdrop)
  25 {
  26         const struct ip6t_hl_info *info = matchinfo;
  27         const struct ipv6hdr *ip6h = skb->nh.ipv6h;
  28
  29         switch (info->mode) {
  30                 case IP6T_HL_EQ:
  31                         return (ip6h->hop_limit == info->hop_limit);
  32                         break;
  33                 case IP6T_HL_NE:
  34                         return (!(ip6h->hop_limit == info->hop_limit));
  35                         break;
  36                 case IP6T_HL_LT:
  37                         return (ip6h->hop_limit < info->hop_limit);
  38                         break;
  39                 case IP6T_HL_GT:
  40                         return (ip6h->hop_limit > info->hop_limit);
  41                         break;
  42                 default:
  43                         printk(KERN_WARNING "ip6t_hl: unknown mode %d\n",
  44                                 info->mode);
  45                         return 0;
  46         }
  47
  48         return 0;
  49 }
  50
  51 static int checkentry(const char *tablename, const void *entry,
  52                       void *matchinfo, unsigned int matchsize,
  53                       unsigned int hook_mask)
  54 {
  55         if (matchsize != IP6T_ALIGN(sizeof(struct ip6t_hl_info)))
  56                 return 0;
  57
  58         return 1;
  59 }
  60
  61 static struct ip6t_match hl_match = {
  62         .name           = "hl",
  63         .match          = &match,
  64         .checkentry     = &checkentry,
  65         .me             = THIS_MODULE,
  66 };
  67
  68 static int __init init(void)
  69 {
  70         return ip6t_register_match(&hl_match);
  71 }
  72
  73 static void __exit fini(void)
  74 {
  75         ip6t_unregister_match(&hl_match);
  76
  77 }
  78
  79 module_init(init);
  80 module_exit(fini);