net/netfilter/xt_realm.c

   1 /* IP tables module for matching the routing realm
   2  *
   3  * $Id: ipt_realm.c,v 1.3 2004/03/05 13:25:40 laforge Exp $
   4  *
   5  * (C) 2003 by Sampsa Ranta <sampsa@netsonic.fi>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/netdevice.h>
  15 #include <net/route.h>
  16
  17 #include <linux/netfilter_ipv4.h>
  18 #include <linux/netfilter/xt_realm.h>
  19 #include <linux/netfilter/x_tables.h>
  20
  21 MODULE_AUTHOR("Sampsa Ranta <sampsa@netsonic.fi>");
  22 MODULE_LICENSE("GPL");
  23 MODULE_DESCRIPTION("X_tables realm match");
  24 MODULE_ALIAS("ipt_realm");
  25
  26 static int
  27 match(const struct sk_buff *skb,
  28       const struct net_device *in,
  29       const struct net_device *out,
  30       const void *matchinfo,
  31       int offset,
  32       unsigned int protoff,
  33       int *hotdrop)
  34 {
  35         const struct xt_realm_info *info = matchinfo;
  36         struct dst_entry *dst = skb->dst;
  37
  38         return (info->id == (dst->tclassid & info->mask)) ^ info->invert;
  39 }
  40
  41 static int check(const char *tablename,
  42                  const void *ip,
  43                  void *matchinfo,
  44                  unsigned int matchsize,
  45                  unsigned int hook_mask)
  46 {
  47         if (hook_mask
  48             & ~((1 << NF_IP_POST_ROUTING) | (1 << NF_IP_FORWARD) |
  49                 (1 << NF_IP_LOCAL_OUT) | (1 << NF_IP_LOCAL_IN))) {
  50                 printk("xt_realm: only valid for POST_ROUTING, LOCAL_OUT, "
  51                        "LOCAL_IN or FORWARD.\n");
  52                 return 0;
  53         }
  54         if (matchsize != XT_ALIGN(sizeof(struct xt_realm_info))) {
  55                 printk("xt_realm: invalid matchsize.\n");
  56                 return 0;
  57         }
  58         return 1;
  59 }
  60
  61 static struct xt_match realm_match = {
  62         .name           = "realm",
  63         .match          = match,
  64         .checkentry     = check,
  65         .me             = THIS_MODULE
  66 };
  67
  68 static int __init init(void)
  69 {
  70         return xt_register_match(AF_INET, &realm_match);
  71 }
  72
  73 static void __exit fini(void)
  74 {
  75         xt_unregister_match(AF_INET, &realm_match);
  76 }
  77
  78 module_init(init);
  79 module_exit(fini);