net/ipv4/netfilter/ipt_mark.c

   1 /* Kernel module to match NFMARK values. */
   2
   3 /* (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
   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 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12
  13 #include <linux/netfilter_ipv4/ipt_mark.h>
  14 #include <linux/netfilter_ipv4/ip_tables.h>
  15
  16 MODULE_LICENSE("GPL");
  17 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
  18 MODULE_DESCRIPTION("iptables mark matching module");
  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       int *hotdrop)
  27 {
  28         const struct ipt_mark_info *info = matchinfo;
  29
  30         return ((skb->nfmark & info->mask) == info->mark) ^ info->invert;
  31 }
  32
  33 static int
  34 checkentry(const char *tablename,
  35            const struct ipt_ip *ip,
  36            void *matchinfo,
  37            unsigned int matchsize,
  38            unsigned int hook_mask)
  39 {
  40         struct ipt_mark_info *minfo = (struct ipt_mark_info *) matchinfo;
  41
  42         if (matchsize != IPT_ALIGN(sizeof(struct ipt_mark_info)))
  43                 return 0;
  44
  45         if (minfo->mark > 0xffffffff || minfo->mask > 0xffffffff) {
  46                 printk(KERN_WARNING "mark: only supports 32bit mark\n");
  47                 return 0;
  48         }
  49
  50         return 1;
  51 }
  52
  53 static struct ipt_match mark_match = {
  54         .name           = "mark",
  55         .match          = &match,
  56         .checkentry     = &checkentry,
  57         .me             = THIS_MODULE,
  58 };
  59
  60 static int __init init(void)
  61 {
  62         return ipt_register_match(&mark_match);
  63 }
  64
  65 static void __exit fini(void)
  66 {
  67         ipt_unregister_match(&mark_match);
  68 }
  69
  70 module_init(init);
  71 module_exit(fini);