root/net/bridge/netfilter/ebtable_nat.c

DEFINITIONS

1. check
2. ebt_nat_dst
3. ebt_nat_src
4. ebtable_nat_init
5. ebtable_nat_fini

/*
 *  ebtable_nat
 *
 *      Authors:
 *      Bart De Schuymer <bdschuym@pandora.be>
 *
 *  April, 2002
 *
 */

#include <linux/netfilter_bridge/ebtables.h>
#include <linux/module.h>

#define NAT_VALID_HOOKS ((1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_LOCAL_OUT) | \
   (1 << NF_BR_POST_ROUTING))

static struct ebt_entries initial_chains[] =
{
        {
                .name   = "PREROUTING",
                .policy = EBT_ACCEPT,
        },
        {
                .name   = "OUTPUT",
                .policy = EBT_ACCEPT,
        },
        {
                .name   = "POSTROUTING",
                .policy = EBT_ACCEPT,
        }
};

static struct ebt_replace_kernel initial_table =
{
        .name           = "nat",
        .valid_hooks    = NAT_VALID_HOOKS,
        .entries_size   = 3 * sizeof(struct ebt_entries),
        .hook_entry     = {
                [NF_BR_PRE_ROUTING]     = &initial_chains[0],
                [NF_BR_LOCAL_OUT]       = &initial_chains[1],
                [NF_BR_POST_ROUTING]    = &initial_chains[2],
        },
        .entries        = (char *)initial_chains,
};

static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
{
        if (valid_hooks & ~NAT_VALID_HOOKS)
                return -EINVAL;
        return 0;
}

static struct ebt_table frame_nat =
{
        .name           = "nat",
        .table          = &initial_table,
        .valid_hooks    = NAT_VALID_HOOKS,
        .lock           = __RW_LOCK_UNLOCKED(frame_nat.lock),
        .check          = check,
        .me             = THIS_MODULE,
};

static unsigned int
ebt_nat_dst(unsigned int hook, struct sk_buff *skb, const struct net_device *in
   , const struct net_device *out, int (*okfn)(struct sk_buff *))
{
        return ebt_do_table(hook, skb, in, out, &frame_nat);
}

static unsigned int
ebt_nat_src(unsigned int hook, struct sk_buff *skb, const struct net_device *in
   , const struct net_device *out, int (*okfn)(struct sk_buff *))
{
        return ebt_do_table(hook, skb, in, out, &frame_nat);
}

static struct nf_hook_ops ebt_ops_nat[] __read_mostly = {
        {
                .hook           = ebt_nat_dst,
                .owner          = THIS_MODULE,
                .pf             = PF_BRIDGE,
                .hooknum        = NF_BR_LOCAL_OUT,
                .priority       = NF_BR_PRI_NAT_DST_OTHER,
        },
        {
                .hook           = ebt_nat_src,
                .owner          = THIS_MODULE,
                .pf             = PF_BRIDGE,
                .hooknum        = NF_BR_POST_ROUTING,
                .priority       = NF_BR_PRI_NAT_SRC,
        },
        {
                .hook           = ebt_nat_dst,
                .owner          = THIS_MODULE,
                .pf             = PF_BRIDGE,
                .hooknum        = NF_BR_PRE_ROUTING,
                .priority       = NF_BR_PRI_NAT_DST_BRIDGED,
        },
};

static int __init ebtable_nat_init(void)
{
        int ret;

        ret = ebt_register_table(&frame_nat);
        if (ret < 0)
                return ret;
        ret = nf_register_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
        if (ret < 0)
                ebt_unregister_table(&frame_nat);
        return ret;
}

static void __exit ebtable_nat_fini(void)
{
        nf_unregister_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
        ebt_unregister_table(&frame_nat);
}

module_init(ebtable_nat_init);
module_exit(ebtable_nat_fini);
MODULE_LICENSE("GPL");