xt_pkttype.c

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/* (C) 1999-2001 Michal Ludvig <[email protected]>
 *
 * 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/if_ether.h>
#include <linux/if_packet.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>

#include <linux/netfilter/xt_pkttype.h>
#include <linux/netfilter/x_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michal Ludvig <[email protected]>");
MODULE_DESCRIPTION("Xtables: link layer packet type match");
MODULE_ALIAS("ipt_pkttype");
MODULE_ALIAS("ip6t_pkttype");

static bool
pkttype_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
    const struct xt_pkttype_info *info = par->matchinfo;
    u_int8_t type;

    if (skb->pkt_type != PACKET_LOOPBACK)
        type = skb->pkt_type;
    else if (par->family == NFPROTO_IPV4 &&
        ipv4_is_multicast(ip_hdr(skb)->daddr))
        type = PACKET_MULTICAST;
    else if (par->family == NFPROTO_IPV6 &&
        ipv6_hdr(skb)->daddr.s6_addr[0] == 0xFF)
        type = PACKET_MULTICAST;
    else
        type = PACKET_BROADCAST;

    return (type == info->pkttype) ^ info->invert;
}

static struct xt_match pkttype_mt_reg __read_mostly = {
    .name      = "pkttype",
    .revision  = 0,
    .family    = NFPROTO_UNSPEC,
    .match     = pkttype_mt,
    .matchsize = sizeof(struct xt_pkttype_info),
    .me        = THIS_MODULE,
};

static int __init pkttype_mt_init(void)
{
    return xt_register_match(&pkttype_mt_reg);
}

static void __exit pkttype_mt_exit(void)
{
    xt_unregister_match(&pkttype_mt_reg);
}

module_init(pkttype_mt_init);
module_exit(pkttype_mt_exit);