net/ipv6/netfilter/ip6t_length.c

   1 /* Length Match - IPv6 Port */
   2
   3 /* (C) 1999-2001 James Morris <jmorros@intercode.com.au>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/netfilter_ipv6/ip6t_length.h>
  14 #include <linux/netfilter_ipv6/ip6_tables.h>
  15
  16 MODULE_LICENSE("GPL");
  17 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
  18 MODULE_DESCRIPTION("IPv6 packet length match");
  19
  20 static int
  21 match(const struct sk_buff *skb,
  22       const struct net_device *in,
  23       const struct net_device *out,
  24       const void *matchinfo,
  25       int offset,
  26       unsigned int protoff,
  27       int *hotdrop)
  28 {
  29         const struct ip6t_length_info *info = matchinfo;
  30         u_int16_t pktlen = ntohs(skb->nh.ipv6h->payload_len) + sizeof(struct ipv6hdr);
  31
  32         return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
  33 }
  34
  35 static int
  36 checkentry(const char *tablename,
  37            const struct ip6t_ip6 *ip,
  38            void *matchinfo,
  39            unsigned int matchsize,
  40            unsigned int hook_mask)
  41 {
  42         if (matchsize != IP6T_ALIGN(sizeof(struct ip6t_length_info)))
  43                 return 0;
  44
  45         return 1;
  46 }
  47
  48 static struct ip6t_match length_match = {
  49         .name           = "length",
  50         .match          = &match,
  51         .checkentry     = &checkentry,
  52         .me             = THIS_MODULE,
  53 };
  54
  55 static int __init init(void)
  56 {
  57         return ip6t_register_match(&length_match);
  58 }
  59
  60 static void __exit fini(void)
  61 {
  62         ip6t_unregister_match(&length_match);
  63 }
  64
  65 module_init(init);
  66 module_exit(fini);