root/net/netfilter/xt_physdev.c

DEFINITIONS

1. physdev_mt
2. physdev_mt_check
3. physdev_mt_init
4. physdev_mt_exit

/* Kernel module to match the bridge port in and
 * out device for IP packets coming into contact with a bridge. */

/* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
 *
 * 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/netfilter_bridge.h>
#include <linux/netfilter/xt_physdev.h>
#include <linux/netfilter/x_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
MODULE_DESCRIPTION("Xtables: Bridge physical device match");
MODULE_ALIAS("ipt_physdev");
MODULE_ALIAS("ip6t_physdev");

static bool
physdev_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
        int i;
        static const char nulldevname[IFNAMSIZ];
        const struct xt_physdev_info *info = par->matchinfo;
        bool ret;
        const char *indev, *outdev;
        const struct nf_bridge_info *nf_bridge;

        /* Not a bridged IP packet or no info available yet:
         * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
         * the destination device will be a bridge. */
        if (!(nf_bridge = skb->nf_bridge)) {
                /* Return MATCH if the invert flags of the used options are on */
                if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
                    !(info->invert & XT_PHYSDEV_OP_BRIDGED))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
                    !(info->invert & XT_PHYSDEV_OP_ISIN))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
                    !(info->invert & XT_PHYSDEV_OP_ISOUT))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
                    !(info->invert & XT_PHYSDEV_OP_IN))
                        return false;
                if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
                    !(info->invert & XT_PHYSDEV_OP_OUT))
                        return false;
                return true;
        }

        /* This only makes sense in the FORWARD and POSTROUTING chains */
        if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
            (!!(nf_bridge->mask & BRNF_BRIDGED) ^
            !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
                return false;

        if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
            (!nf_bridge->physindev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
            (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
            (!nf_bridge->physoutdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
                return false;

        if (!(info->bitmask & XT_PHYSDEV_OP_IN))
                goto match_outdev;
        indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
        for (i = 0, ret = false; i < IFNAMSIZ/sizeof(unsigned int); i++) {
                ret |= (((const unsigned int *)indev)[i]
                        ^ ((const unsigned int *)info->physindev)[i])
                        & ((const unsigned int *)info->in_mask)[i];
        }

        if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
                return false;

match_outdev:
        if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
                return true;
        outdev = nf_bridge->physoutdev ?
                 nf_bridge->physoutdev->name : nulldevname;
        for (i = 0, ret = false; i < IFNAMSIZ/sizeof(unsigned int); i++) {
                ret |= (((const unsigned int *)outdev)[i]
                        ^ ((const unsigned int *)info->physoutdev)[i])
                        & ((const unsigned int *)info->out_mask)[i];
        }

        return ret ^ !(info->invert & XT_PHYSDEV_OP_OUT);
}

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

        if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
            info->bitmask & ~XT_PHYSDEV_OP_MASK)
                return false;
        if (info->bitmask & XT_PHYSDEV_OP_OUT &&
            (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
             info->invert & XT_PHYSDEV_OP_BRIDGED) &&
            par->hook_mask & ((1 << NF_INET_LOCAL_OUT) |
            (1 << NF_INET_FORWARD) | (1 << NF_INET_POST_ROUTING))) {
                printk(KERN_WARNING "physdev match: using --physdev-out in the "
                       "OUTPUT, FORWARD and POSTROUTING chains for non-bridged "
                       "traffic is not supported anymore.\n");
                if (par->hook_mask & (1 << NF_INET_LOCAL_OUT))
                        return false;
        }
        return true;
}

static struct xt_match physdev_mt_reg __read_mostly = {
        .name       = "physdev",
        .revision   = 0,
        .family     = NFPROTO_UNSPEC,
        .checkentry = physdev_mt_check,
        .match      = physdev_mt,
        .matchsize  = sizeof(struct xt_physdev_info),
        .me         = THIS_MODULE,
};

static int __init physdev_mt_init(void)
{
        return xt_register_match(&physdev_mt_reg);
}

static void __exit physdev_mt_exit(void)
{
        xt_unregister_match(&physdev_mt_reg);
}

module_init(physdev_mt_init);
module_exit(physdev_mt_exit);