root/net/bridge/netfilter/ebt_ip.c

DEFINITIONS

1. ebt_ip_mt
2. ebt_ip_mt_check
3. ebt_ip_init
4. ebt_ip_fini

/*
 *  ebt_ip
 *
 *      Authors:
 *      Bart De Schuymer <bdschuym@pandora.be>
 *
 *  April, 2002
 *
 *  Changes:
 *    added ip-sport and ip-dport
 *    Innominate Security Technologies AG <mhopf@innominate.com>
 *    September, 2002
 */
#include <linux/ip.h>
#include <net/ip.h>
#include <linux/in.h>
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_ip.h>

struct tcpudphdr {
        __be16 src;
        __be16 dst;
};

static bool
ebt_ip_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
        const struct ebt_ip_info *info = par->matchinfo;
        const struct iphdr *ih;
        struct iphdr _iph;
        const struct tcpudphdr *pptr;
        struct tcpudphdr _ports;

        ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
        if (ih == NULL)
                return false;
        if (info->bitmask & EBT_IP_TOS &&
           FWINV(info->tos != ih->tos, EBT_IP_TOS))
                return false;
        if (info->bitmask & EBT_IP_SOURCE &&
           FWINV((ih->saddr & info->smsk) !=
           info->saddr, EBT_IP_SOURCE))
                return false;
        if ((info->bitmask & EBT_IP_DEST) &&
           FWINV((ih->daddr & info->dmsk) !=
           info->daddr, EBT_IP_DEST))
                return false;
        if (info->bitmask & EBT_IP_PROTO) {
                if (FWINV(info->protocol != ih->protocol, EBT_IP_PROTO))
                        return false;
                if (!(info->bitmask & EBT_IP_DPORT) &&
                    !(info->bitmask & EBT_IP_SPORT))
                        return true;
                if (ntohs(ih->frag_off) & IP_OFFSET)
                        return false;
                pptr = skb_header_pointer(skb, ih->ihl*4,
                                          sizeof(_ports), &_ports);
                if (pptr == NULL)
                        return false;
                if (info->bitmask & EBT_IP_DPORT) {
                        u32 dst = ntohs(pptr->dst);
                        if (FWINV(dst < info->dport[0] ||
                                  dst > info->dport[1],
                                  EBT_IP_DPORT))
                        return false;
                }
                if (info->bitmask & EBT_IP_SPORT) {
                        u32 src = ntohs(pptr->src);
                        if (FWINV(src < info->sport[0] ||
                                  src > info->sport[1],
                                  EBT_IP_SPORT))
                        return false;
                }
        }
        return true;
}

static bool ebt_ip_mt_check(const struct xt_mtchk_param *par)
{
        const struct ebt_ip_info *info = par->matchinfo;
        const struct ebt_entry *e = par->entryinfo;

        if (e->ethproto != htons(ETH_P_IP) ||
           e->invflags & EBT_IPROTO)
                return false;
        if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
                return false;
        if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
                if (info->invflags & EBT_IP_PROTO)
                        return false;
                if (info->protocol != IPPROTO_TCP &&
                    info->protocol != IPPROTO_UDP &&
                    info->protocol != IPPROTO_UDPLITE &&
                    info->protocol != IPPROTO_SCTP &&
                    info->protocol != IPPROTO_DCCP)
                         return false;
        }
        if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
                return false;
        if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
                return false;
        return true;
}

static struct xt_match ebt_ip_mt_reg __read_mostly = {
        .name           = "ip",
        .revision       = 0,
        .family         = NFPROTO_BRIDGE,
        .match          = ebt_ip_mt,
        .checkentry     = ebt_ip_mt_check,
        .matchsize      = XT_ALIGN(sizeof(struct ebt_ip_info)),
        .me             = THIS_MODULE,
};

static int __init ebt_ip_init(void)
{
        return xt_register_match(&ebt_ip_mt_reg);
}

static void __exit ebt_ip_fini(void)
{
        xt_unregister_match(&ebt_ip_mt_reg);
}

module_init(ebt_ip_init);
module_exit(ebt_ip_fini);
MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
MODULE_LICENSE("GPL");