LXR linux/net/netfilter/xt

   1/*
   2 * IP tables module for matching the value of the TTL
   3 * (C) 2000,2001 by Harald Welte <laforge@netfilter.org>
   4 *
   5 * Hop Limit matching module
   6 * (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12
  13#include <linux/ip.h>
  14#include <linux/ipv6.h>
  15#include <linux/module.h>
  16#include <linux/skbuff.h>
  17
  18#include <linux/netfilter/x_tables.h>
  19#include <linux/netfilter_ipv4/ipt_ttl.h>
  20#include <linux/netfilter_ipv6/ip6t_hl.h>
  21
  22MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
  23MODULE_DESCRIPTION("Xtables: Hoplimit/TTL field match");
  24MODULE_LICENSE("GPL");
  25MODULE_ALIAS("ipt_ttl");
  26MODULE_ALIAS("ip6t_hl");
  27
  28static bool ttl_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  29{
  30        const struct ipt_ttl_info *info = par->matchinfo;
  31        const u8 ttl = ip_hdr(skb)->ttl;
  32
  33        switch (info->mode) {
  34                case IPT_TTL_EQ:
  35                        return ttl == info->ttl;
  36                case IPT_TTL_NE:
  37                        return ttl != info->ttl;
  38                case IPT_TTL_LT:
  39                        return ttl < info->ttl;
  40                case IPT_TTL_GT:
  41                        return ttl > info->ttl;
  42                default:
  43                        printk(KERN_WARNING "ipt_ttl: unknown mode %d\n",
  44                                info->mode);
  45                        return false;
  46        }
  47
  48        return false;
  49}
  50
  51static bool hl_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
  52{
  53        const struct ip6t_hl_info *info = par->matchinfo;
  54        const struct ipv6hdr *ip6h = ipv6_hdr(skb);
  55
  56        switch (info->mode) {
  57                case IP6T_HL_EQ:
  58                        return ip6h->hop_limit == info->hop_limit;
  59                        break;
  60                case IP6T_HL_NE:
  61                        return ip6h->hop_limit != info->hop_limit;
  62                        break;
  63                case IP6T_HL_LT:
  64                        return ip6h->hop_limit < info->hop_limit;
  65                        break;
  66                case IP6T_HL_GT:
  67                        return ip6h->hop_limit > info->hop_limit;
  68                        break;
  69                default:
  70                        printk(KERN_WARNING "ip6t_hl: unknown mode %d\n",
  71                                info->mode);
  72                        return false;
  73        }
  74
  75        return false;
  76}
  77
  78static struct xt_match hl_mt_reg[] __read_mostly = {
  79        {
  80                .name       = "ttl",
  81                .revision   = 0,
  82                .family     = NFPROTO_IPV4,
  83                .match      = ttl_mt,
  84                .matchsize  = sizeof(struct ipt_ttl_info),
  85                .me         = THIS_MODULE,
  86        },
  87        {
  88                .name       = "hl",
  89                .revision   = 0,
  90                .family     = NFPROTO_IPV6,
  91                .match      = hl_mt6,
  92                .matchsize  = sizeof(struct ip6t_hl_info),
  93                .me         = THIS_MODULE,
  94        },
  95};
  96
  97static int __init hl_mt_init(void)
  98{
  99        return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
 100}
 101
 102static void __exit hl_mt_exit(void)
 103{
 104        xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
 105}
 106
 107module_init(hl_mt_init);
 108module_exit(hl_mt_exit);
 109