root/net/ipv4/netfilter/ipt_addrtype.c

DEFINITIONS

1. match_type
2. addrtype_mt_v0
3. addrtype_mt_v1
4. addrtype_mt_checkentry_v1
5. addrtype_mt_init
6. addrtype_mt_exit

/*
 *  iptables module to match inet_addr_type() of an ip.
 *
 *  Copyright (c) 2004 Patrick McHardy <kaber@trash.net>
 *  (C) 2007 Laszlo Attila Toth <panther@balabit.hu>
 *
 *  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/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/ip.h>
#include <net/route.h>

#include <linux/netfilter_ipv4/ipt_addrtype.h>
#include <linux/netfilter/x_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("Xtables: address type match for IPv4");

static inline bool match_type(const struct net_device *dev, __be32 addr,
                              u_int16_t mask)
{
        return !!(mask & (1 << inet_dev_addr_type(&init_net, dev, addr)));
}

static bool
addrtype_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
{
        const struct ipt_addrtype_info *info = par->matchinfo;
        const struct iphdr *iph = ip_hdr(skb);
        bool ret = true;

        if (info->source)
                ret &= match_type(NULL, iph->saddr, info->source) ^
                       info->invert_source;
        if (info->dest)
                ret &= match_type(NULL, iph->daddr, info->dest) ^
                       info->invert_dest;

        return ret;
}

static bool
addrtype_mt_v1(const struct sk_buff *skb, const struct xt_match_param *par)
{
        const struct ipt_addrtype_info_v1 *info = par->matchinfo;
        const struct iphdr *iph = ip_hdr(skb);
        const struct net_device *dev = NULL;
        bool ret = true;

        if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN)
                dev = par->in;
        else if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT)
                dev = par->out;

        if (info->source)
                ret &= match_type(dev, iph->saddr, info->source) ^
                       (info->flags & IPT_ADDRTYPE_INVERT_SOURCE);
        if (ret && info->dest)
                ret &= match_type(dev, iph->daddr, info->dest) ^
                       !!(info->flags & IPT_ADDRTYPE_INVERT_DEST);
        return ret;
}

static bool addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
{
        struct ipt_addrtype_info_v1 *info = par->matchinfo;

        if (info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN &&
            info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
                printk(KERN_ERR "ipt_addrtype: both incoming and outgoing "
                                "interface limitation cannot be selected\n");
                return false;
        }

        if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
            (1 << NF_INET_LOCAL_IN)) &&
            info->flags & IPT_ADDRTYPE_LIMIT_IFACE_OUT) {
                printk(KERN_ERR "ipt_addrtype: output interface limitation "
                                "not valid in PRE_ROUTING and INPUT\n");
                return false;
        }

        if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
            (1 << NF_INET_LOCAL_OUT)) &&
            info->flags & IPT_ADDRTYPE_LIMIT_IFACE_IN) {
                printk(KERN_ERR "ipt_addrtype: input interface limitation "
                                "not valid in POST_ROUTING and OUTPUT\n");
                return false;
        }

        return true;
}

static struct xt_match addrtype_mt_reg[] __read_mostly = {
        {
                .name           = "addrtype",
                .family         = NFPROTO_IPV4,
                .match          = addrtype_mt_v0,
                .matchsize      = sizeof(struct ipt_addrtype_info),
                .me             = THIS_MODULE
        },
        {
                .name           = "addrtype",
                .family         = NFPROTO_IPV4,
                .revision       = 1,
                .match          = addrtype_mt_v1,
                .checkentry     = addrtype_mt_checkentry_v1,
                .matchsize      = sizeof(struct ipt_addrtype_info_v1),
                .me             = THIS_MODULE
        }
};

static int __init addrtype_mt_init(void)
{
        return xt_register_matches(addrtype_mt_reg,
                                   ARRAY_SIZE(addrtype_mt_reg));
}

static void __exit addrtype_mt_exit(void)
{
        xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
}

module_init(addrtype_mt_init);
module_exit(addrtype_mt_exit);