xtables-addons/extensions/xt_ipaddr.c

/*
 *	"ipaddr" demo match for Xtables
 *	Copyright © Jan Engelhardt, 2008-2009
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the WTF Public License version 2 or
 *      (at your option) any later version.
 */
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <net/ipv6.h>
#include "compat_xtables.h"
#include "xt_ipaddr.h"

static bool ipaddr_mt4(const struct sk_buff *skb, struct xt_action_param *par)
{
	const struct xt_ipaddr_mtinfo *info = par->matchinfo;
	const struct iphdr *iph = ip_hdr(skb);

	printk(KERN_INFO
	       "xt_ipaddr: IN=%s OUT=%s "
	       "SRC=" NIPQUAD_FMT " DST=" NIPQUAD_FMT " "
	       "IPSRC=" NIPQUAD_FMT " IPDST=" NIPQUAD_FMT "\n",
	       (par->in != NULL) ? par->in->name : "",
	       (par->out != NULL) ? par->out->name : "",
	       NIPQUAD(iph->saddr), NIPQUAD(iph->daddr),
	       NIPQUAD(info->src), NIPQUAD(info->dst));

	if (info->flags & XT_IPADDR_SRC)
		if ((iph->saddr != info->src.ip) ^
		    !!(info->flags & XT_IPADDR_SRC_INV)) {
			printk(KERN_NOTICE "src IP - no match\n");
			return false;
		}

	if (info->flags & XT_IPADDR_DST)
		if ((iph->daddr != info->dst.ip) ^
		    !!(info->flags & XT_IPADDR_DST_INV)) {
			printk(KERN_NOTICE "dst IP - no match\n");
			return false;
		}

	return true;
}

static bool ipaddr_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
	const struct xt_ipaddr_mtinfo *info = par->matchinfo;
	const struct ipv6hdr *iph = ipv6_hdr(skb);

	printk(KERN_INFO
	       "xt_ipaddr: IN=%s OUT=%s "
	       "SRC=" NIP6_FMT " DST=" NIP6_FMT " "
	       "IPSRC=" NIP6_FMT " IPDST=" NIP6_FMT "\n",
	       (par->in != NULL) ? par->in->name : "",
	       (par->out != NULL) ? par->out->name : "",
	       NIP6(iph->saddr), NIP6(iph->daddr),
	       NIP6(info->src.in6), NIP6(info->dst.in6));

	if (info->flags & XT_IPADDR_SRC)
		if ((ipv6_addr_cmp(&iph->saddr, &info->src.in6) != 0) ^
		    !!(info->flags & XT_IPADDR_SRC_INV)) {
			printk(KERN_NOTICE "src IP - no match\n");
			return false;
		}

	if (info->flags & XT_IPADDR_DST)
		if ((ipv6_addr_cmp(&iph->daddr, &info->dst.in6) != 0) ^
		    !!(info->flags & XT_IPADDR_DST_INV)) {
			printk(KERN_NOTICE "dst IP - no match\n");
			return false;
		}

	return true;
}

static int ipaddr_mt_check(const struct xt_mtchk_param *par)
{
	const struct xt_ipaddr_mtinfo *info = par->matchinfo;

	printk(KERN_INFO "xt_ipaddr: Added a rule with -m ipaddr in "
	       "the %s table; this rule is reachable through hooks 0x%x\n",
	       par->table, par->hook_mask);

	if (par->match->family == NFPROTO_IPV4 &&
	    ntohl(info->src.ip) == 0xDEADBEEF) {
		printk(KERN_INFO "xt_ipaddr: I just thought I do not want "
		       "to let you match on 222.173.190.239\n");
		return -EPERM;
	}

	return 0;
}

static void ipaddr_mt_destroy(const struct xt_mtdtor_param *par)
{
	printk(KERN_INFO "One rule with ipaddr match got deleted\n");
}

static struct xt_match ipaddr_mt_reg[] __read_mostly = {
	{
		.name       = "ipaddr",
		.revision   = 0,
		.family     = NFPROTO_IPV4,
		.match      = ipaddr_mt4,
		.checkentry = ipaddr_mt_check,
		.destroy    = ipaddr_mt_destroy,
		.matchsize  = XT_ALIGN(sizeof(struct xt_ipaddr_mtinfo)),
		.me         = THIS_MODULE,
	},
	{
		.name       = "ipaddr",
		.revision   = 0,
		.family     = NFPROTO_IPV6,
		.match      = ipaddr_mt6,
		.checkentry = ipaddr_mt_check,
		.destroy    = ipaddr_mt_destroy,
		.matchsize  = XT_ALIGN(sizeof(struct xt_ipaddr_mtinfo)),
		.me         = THIS_MODULE,
	},
};

static int __init ipaddr_mt_init(void)
{
	return xt_register_matches(ipaddr_mt_reg, ARRAY_SIZE(ipaddr_mt_reg));
}

static void __exit ipaddr_mt_exit(void)
{
	xt_unregister_matches(ipaddr_mt_reg, ARRAY_SIZE(ipaddr_mt_reg));
}

module_init(ipaddr_mt_init);
module_exit(ipaddr_mt_exit);
MODULE_DESCRIPTION("Xtables: Match source/destination address");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_ipaddr");
MODULE_ALIAS("ip6t_ipaddr");