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/*
* Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
* Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
* Copyright (c) 2012 Intel Corporation
*
* 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.
*
* Development of this code funded by Astaro AG (http://www.astaro.com/)
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_ipv4.h>
#include <net/netfilter/nf_nat_l3proto.h>
#include <net/ip.h>
/*
* NAT chains
*/
static unsigned int nf_nat_fn(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
struct nf_conn_nat *nat;
enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum);
struct nft_pktinfo pkt;
unsigned int ret;
if (ct == NULL || nf_ct_is_untracked(ct))
return NF_ACCEPT;
NF_CT_ASSERT(!(ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)));
nat = nfct_nat(ct);
if (nat == NULL) {
/* Conntrack module was loaded late, can't add extension. */
if (nf_ct_is_confirmed(ct))
return NF_ACCEPT;
nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
if (nat == NULL)
return NF_ACCEPT;
}
switch (ctinfo) {
case IP_CT_RELATED:
case IP_CT_RELATED + IP_CT_IS_REPLY:
if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
ops->hooknum))
return NF_DROP;
else
return NF_ACCEPT;
}
/* Fall through */
case IP_CT_NEW:
if (nf_nat_initialized(ct, maniptype))
break;
nft_set_pktinfo_ipv4(&pkt, ops, skb, in, out);
ret = nft_do_chain_pktinfo(&pkt, ops);
if (ret != NF_ACCEPT)
return ret;
if (!nf_nat_initialized(ct, maniptype)) {
ret = nf_nat_alloc_null_binding(ct, ops->hooknum);
if (ret != NF_ACCEPT)
return ret;
}
default:
break;
}
return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
}
static unsigned int nf_nat_prerouting(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
__be32 daddr = ip_hdr(skb)->daddr;
unsigned int ret;
ret = nf_nat_fn(ops, skb, in, out, okfn);
if (ret != NF_DROP && ret != NF_STOLEN &&
ip_hdr(skb)->daddr != daddr) {
skb_dst_drop(skb);
}
return ret;
}
static unsigned int nf_nat_postrouting(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
enum ip_conntrack_info ctinfo __maybe_unused;
const struct nf_conn *ct __maybe_unused;
unsigned int ret;
ret = nf_nat_fn(ops, skb, in, out, okfn);
#ifdef CONFIG_XFRM
if (ret != NF_DROP && ret != NF_STOLEN &&
(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (ct->tuplehash[dir].tuple.src.u3.ip !=
ct->tuplehash[!dir].tuple.dst.u3.ip ||
ct->tuplehash[dir].tuple.src.u.all !=
ct->tuplehash[!dir].tuple.dst.u.all)
return nf_xfrm_me_harder(skb, AF_INET) == 0 ?
ret : NF_DROP;
}
#endif
return ret;
}
static unsigned int nf_nat_output(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
enum ip_conntrack_info ctinfo;
const struct nf_conn *ct;
unsigned int ret;
ret = nf_nat_fn(ops, skb, in, out, okfn);
if (ret != NF_DROP && ret != NF_STOLEN &&
(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
if (ct->tuplehash[dir].tuple.dst.u3.ip !=
ct->tuplehash[!dir].tuple.src.u3.ip) {
if (ip_route_me_harder(skb, RTN_UNSPEC))
ret = NF_DROP;
}
#ifdef CONFIG_XFRM
else if (ct->tuplehash[dir].tuple.dst.u.all !=
ct->tuplehash[!dir].tuple.src.u.all)
if (nf_xfrm_me_harder(skb, AF_INET))
ret = NF_DROP;
#endif
}
return ret;
}
static struct nf_chain_type nft_chain_nat_ipv4 = {
.family = NFPROTO_IPV4,
.name = "nat",
.type = NFT_CHAIN_T_NAT,
.hook_mask = (1 << NF_INET_PRE_ROUTING) |
(1 << NF_INET_POST_ROUTING) |
(1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_LOCAL_IN),
.fn = {
[NF_INET_PRE_ROUTING] = nf_nat_prerouting,
[NF_INET_POST_ROUTING] = nf_nat_postrouting,
[NF_INET_LOCAL_OUT] = nf_nat_output,
[NF_INET_LOCAL_IN] = nf_nat_fn,
},
.me = THIS_MODULE,
};
static int __init nft_chain_nat_init(void)
{
int err;
err = nft_register_chain_type(&nft_chain_nat_ipv4);
if (err < 0)
return err;
return 0;
}
static void __exit nft_chain_nat_exit(void)
{
nft_unregister_chain_type(&nft_chain_nat_ipv4);
}
module_init(nft_chain_nat_init);
module_exit(nft_chain_nat_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_ALIAS_NFT_CHAIN(AF_INET, "nat");
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