xt_nat.c

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/*
 * (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <[email protected]>
 * (C) 2011 Patrick McHardy <[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/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <net/netfilter/nf_nat_core.h>

static int xt_nat_checkentry_v0(const struct xt_tgchk_param *par)
{
    const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;

    if (mr->rangesize != 1) {
        pr_info("%s: multiple ranges no longer supported\n",
            par->target->name);
        return -EINVAL;
    }
    return 0;
}

static void xt_nat_convert_range(struct nf_nat_range *dst,
                 const struct nf_nat_ipv4_range *src)
{
    memset(&dst->min_addr, 0, sizeof(dst->min_addr));
    memset(&dst->max_addr, 0, sizeof(dst->max_addr));

    dst->flags   = src->flags;
    dst->min_addr.ip = src->min_ip;
    dst->max_addr.ip = src->max_ip;
    dst->min_proto   = src->min;
    dst->max_proto   = src->max;
}

static unsigned int
xt_snat_target_v0(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
    struct nf_nat_range range;
    enum ip_conntrack_info ctinfo;
    struct nf_conn *ct;

    ct = nf_ct_get(skb, &ctinfo);
    NF_CT_ASSERT(ct != NULL &&
             (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
              ctinfo == IP_CT_RELATED_REPLY));

    xt_nat_convert_range(&range, &mr->range[0]);
    return nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
}

static unsigned int
xt_dnat_target_v0(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
    struct nf_nat_range range;
    enum ip_conntrack_info ctinfo;
    struct nf_conn *ct;

    ct = nf_ct_get(skb, &ctinfo);
    NF_CT_ASSERT(ct != NULL &&
             (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));

    xt_nat_convert_range(&range, &mr->range[0]);
    return nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
}

static unsigned int
xt_snat_target_v1(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct nf_nat_range *range = par->targinfo;
    enum ip_conntrack_info ctinfo;
    struct nf_conn *ct;

    ct = nf_ct_get(skb, &ctinfo);
    NF_CT_ASSERT(ct != NULL &&
             (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
              ctinfo == IP_CT_RELATED_REPLY));

    return nf_nat_setup_info(ct, range, NF_NAT_MANIP_SRC);
}

static unsigned int
xt_dnat_target_v1(struct sk_buff *skb, const struct xt_action_param *par)
{
    const struct nf_nat_range *range = par->targinfo;
    enum ip_conntrack_info ctinfo;
    struct nf_conn *ct;

    ct = nf_ct_get(skb, &ctinfo);
    NF_CT_ASSERT(ct != NULL &&
             (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));

    return nf_nat_setup_info(ct, range, NF_NAT_MANIP_DST);
}

static struct xt_target xt_nat_target_reg[] __read_mostly = {
    {
        .name       = "SNAT",
        .revision   = 0,
        .checkentry = xt_nat_checkentry_v0,
        .target     = xt_snat_target_v0,
        .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
        .family     = NFPROTO_IPV4,
        .table      = "nat",
        .hooks      = (1 << NF_INET_POST_ROUTING) |
                  (1 << NF_INET_LOCAL_IN),
        .me     = THIS_MODULE,
    },
    {
        .name       = "DNAT",
        .revision   = 0,
        .checkentry = xt_nat_checkentry_v0,
        .target     = xt_dnat_target_v0,
        .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
        .family     = NFPROTO_IPV4,
        .table      = "nat",
        .hooks      = (1 << NF_INET_PRE_ROUTING) |
                  (1 << NF_INET_LOCAL_OUT),
        .me     = THIS_MODULE,
    },
    {
        .name       = "SNAT",
        .revision   = 1,
        .target     = xt_snat_target_v1,
        .targetsize = sizeof(struct nf_nat_range),
        .table      = "nat",
        .hooks      = (1 << NF_INET_POST_ROUTING) |
                  (1 << NF_INET_LOCAL_IN),
        .me     = THIS_MODULE,
    },
    {
        .name       = "DNAT",
        .revision   = 1,
        .target     = xt_dnat_target_v1,
        .targetsize = sizeof(struct nf_nat_range),
        .table      = "nat",
        .hooks      = (1 << NF_INET_PRE_ROUTING) |
                  (1 << NF_INET_LOCAL_OUT),
        .me     = THIS_MODULE,
    },
};

static int __init xt_nat_init(void)
{
    return xt_register_targets(xt_nat_target_reg,
                   ARRAY_SIZE(xt_nat_target_reg));
}

static void __exit xt_nat_exit(void)
{
    xt_unregister_targets(xt_nat_target_reg, ARRAY_SIZE(xt_nat_target_reg));
}

module_init(xt_nat_init);
module_exit(xt_nat_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <[email protected]>");
MODULE_ALIAS("ipt_SNAT");
MODULE_ALIAS("ipt_DNAT");
MODULE_ALIAS("ip6t_SNAT");
MODULE_ALIAS("ip6t_DNAT");