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, const struct net_device *in,
  31                  const struct net_device *out, const void *matchinfo,
  32                  int offset, int *hotdrop)
  33 {
  34         const struct ipt_addrtype_info *info = matchinfo;
  35         const struct iphdr *iph = skb->nh.iph;
  36         int ret = 1;
  37
  38         if (info->source)
  39                 ret &= match_type(iph->saddr, info->source)^info->invert_source;
  40         if (info->dest)
  41                 ret &= match_type(iph->daddr, info->dest)^info->invert_dest;
  42
  43         return ret;
  44 }
  45
  46 static int checkentry(const char *tablename, const struct ipt_ip *ip,
  47                       void *matchinfo, unsigned int matchsize,
  48                       unsigned int hook_mask)
  49 {
  50         if (matchsize != IPT_ALIGN(sizeof(struct ipt_addrtype_info))) {
  51                 printk(KERN_ERR "ipt_addrtype: invalid size (%u != %Zu)\n.",
  52                        matchsize, IPT_ALIGN(sizeof(struct ipt_addrtype_info)));
  53                 return 0;
  54         }
  55
  56         return 1;
  57 }
  58
  59 static struct ipt_match addrtype_match = {
  60         .name           = "addrtype",
  61         .match          = match,
  62         .checkentry     = checkentry,
  63         .me             = THIS_MODULE
  64 };
  65
  66 static int __init init(void)
  67 {
  68         return ipt_register_match(&addrtype_match);
  69 }
  70
  71 static void __exit fini(void)
  72 {
  73         ipt_unregister_match(&addrtype_match);
  74 }
  75
  76 module_init(init);
  77 module_exit(fini);