ebt_802_3.c

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/*
 * 802_3
 *
 * Author:
 * Chris Vitale [email protected]
 *
 * May 2003
 *
 */
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_802_3.h>

static bool
ebt_802_3_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
    const struct ebt_802_3_info *info = par->matchinfo;
    const struct ebt_802_3_hdr *hdr = ebt_802_3_hdr(skb);
    __be16 type = hdr->llc.ui.ctrl & IS_UI ? hdr->llc.ui.type : hdr->llc.ni.type;

    if (info->bitmask & EBT_802_3_SAP) {
        if (FWINV(info->sap != hdr->llc.ui.ssap, EBT_802_3_SAP))
            return false;
        if (FWINV(info->sap != hdr->llc.ui.dsap, EBT_802_3_SAP))
            return false;
    }

    if (info->bitmask & EBT_802_3_TYPE) {
        if (!(hdr->llc.ui.dsap == CHECK_TYPE && hdr->llc.ui.ssap == CHECK_TYPE))
            return false;
        if (FWINV(info->type != type, EBT_802_3_TYPE))
            return false;
    }

    return true;
}

static int ebt_802_3_mt_check(const struct xt_mtchk_param *par)
{
    const struct ebt_802_3_info *info = par->matchinfo;

    if (info->bitmask & ~EBT_802_3_MASK || info->invflags & ~EBT_802_3_MASK)
        return -EINVAL;

    return 0;
}

static struct xt_match ebt_802_3_mt_reg __read_mostly = {
    .name       = "802_3",
    .revision   = 0,
    .family     = NFPROTO_BRIDGE,
    .match      = ebt_802_3_mt,
    .checkentry = ebt_802_3_mt_check,
    .matchsize  = sizeof(struct ebt_802_3_info),
    .me     = THIS_MODULE,
};

static int __init ebt_802_3_init(void)
{
    return xt_register_match(&ebt_802_3_mt_reg);
}

static void __exit ebt_802_3_fini(void)
{
    xt_unregister_match(&ebt_802_3_mt_reg);
}

module_init(ebt_802_3_init);
module_exit(ebt_802_3_fini);
MODULE_DESCRIPTION("Ebtables: DSAP/SSAP field and SNAP type matching");
MODULE_LICENSE("GPL");