net/ipv4/netfilter/ipt_mark.c

/* Kernel module to match NFMARK values. */

/* (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/skbuff.h>

#include <linux/netfilter_ipv4/ipt_mark.h>
#include <linux/netfilter_ipv4/ip_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
MODULE_DESCRIPTION("iptables mark matching module");

static int
match(const struct sk_buff *skb,
      const struct net_device *in,
      const struct net_device *out,
      const void *matchinfo,
      int offset,
      int *hotdrop)
{
	const struct ipt_mark_info *info = matchinfo;

	return ((skb->nfmark & info->mask) == info->mark) ^ info->invert;
}

static int
checkentry(const char *tablename,
           const struct ipt_ip *ip,
           void *matchinfo,
           unsigned int matchsize,
           unsigned int hook_mask)
{
	struct ipt_mark_info *minfo = (struct ipt_mark_info *) matchinfo;

	if (matchsize != IPT_ALIGN(sizeof(struct ipt_mark_info)))
		return 0;

	if (minfo->mark > 0xffffffff || minfo->mask > 0xffffffff) {
		printk(KERN_WARNING "mark: only supports 32bit mark\n");
		return 0;
	}

	return 1;
}

static struct ipt_match mark_match = {
	.name		= "mark",
	.match		= &match,
	.checkentry	= &checkentry,
	.me		= THIS_MODULE,
};

static int __init init(void)
{
	return ipt_register_match(&mark_match);
}

static void __exit fini(void)
{
	ipt_unregister_match(&mark_match);
}

module_init(init);
module_exit(fini);