net/ipv4/netfilter/ipt_addrtype.c

   1 /*
   2  *  iptables module to match inet_addr_type() of an ip.
   3  *
   4  *  Copyright (c) 2004 Patrick McHardy <kaber@trash.net>
   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/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/netdevice.h>
  15 #include <linux/ip.h>
  16 #include <net/route.h>
  17
  18 #include <linux/netfilter_ipv4/ipt_addrtype.h>
  19 #include <linux/netfilter_ipv4/ip_tables.h>
  20
  21 MODULE_LICENSE("GPL");
  22 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  23 MODULE_DESCRIPTION("iptables addrtype match");
  24
  25 static inline int match_type(u_int32_t addr, u_int16_t mask)
  26 {
  27         return !!(mask & (1 << inet_addr_type(addr)));
  28 }
  29
  30 static int match(const struct sk_buff *skb,
  31                  const struct net_device *in, const struct net_device *out,
  32                  const struct xt_match *match, const void *matchinfo,
  33                  int offset, unsigned int protoff, int *hotdrop)
  34 {
  35         const struct ipt_addrtype_info *info = matchinfo;
  36         const struct iphdr *iph = skb->nh.iph;
  37         int ret = 1;
  38
  39         if (info->source)
  40                 ret &= match_type(iph->saddr, info->source)^info->invert_source;
  41         if (info->dest)
  42                 ret &= match_type(iph->daddr, info->dest)^info->invert_dest;
  43
  44         return ret;
  45 }
  46
  47 static struct ipt_match addrtype_match = {
  48         .name           = "addrtype",
  49         .match          = match,
  50         .matchsize      = sizeof(struct ipt_addrtype_info),
  51         .me             = THIS_MODULE
  52 };
  53
  54 static int __init ipt_addrtype_init(void)
  55 {
  56         return ipt_register_match(&addrtype_match);
  57 }
  58
  59 static void __exit ipt_addrtype_fini(void)
  60 {
  61         ipt_unregister_match(&addrtype_match);
  62 }
  63
  64 module_init(ipt_addrtype_init);
  65 module_exit(ipt_addrtype_fini);