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netfilter: nft_chain_nat_ipv4: use generic IPv4 NAT code from core
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Use the exported IPv4 NAT functions that are provided by the core. This
removes duplicated code so iptables and nft use the same NAT codebase.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Pablo Neira Ayuso committed Sep 2, 2014
1 parent 30766f4 commit 65cd90a
Showing 1 changed file with 37 additions and 120 deletions.
157 changes: 37 additions & 120 deletions net/ipv4/netfilter/nft_chain_nat_ipv4.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,136 +26,53 @@
#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 *))
static unsigned int nft_nat_do_chain(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
struct nf_conn *ct)
{
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 = nf_ct_nat_ext_add(ct);
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);
nft_set_pktinfo_ipv4(&pkt, ops, skb, in, out);

ret = nft_do_chain(&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);
return nft_do_chain(&pkt, ops);
}

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 *))
static unsigned int nft_nat_ipv4_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 *))
{
__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;
return nf_nat_ipv4_fn(ops, skb, in, out, nft_nat_do_chain);
}

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 *))
static unsigned int nft_nat_ipv4_in(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;
return nf_nat_ipv4_in(ops, skb, in, out, nft_nat_do_chain);
}

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 *))
static unsigned int nft_nat_ipv4_out(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);
return nf_nat_ipv4_out(ops, skb, in, out, nft_nat_do_chain);
}

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 unsigned int nft_nat_ipv4_local_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 *))
{
return nf_nat_ipv4_local_fn(ops, skb, in, out, nft_nat_do_chain);
}

static const struct nf_chain_type nft_chain_nat_ipv4 = {
Expand All @@ -168,10 +85,10 @@ static const struct nf_chain_type nft_chain_nat_ipv4 = {
(1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_LOCAL_IN),
.hooks = {
[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,
[NF_INET_PRE_ROUTING] = nft_nat_ipv4_in,
[NF_INET_POST_ROUTING] = nft_nat_ipv4_out,
[NF_INET_LOCAL_OUT] = nft_nat_ipv4_local_fn,
[NF_INET_LOCAL_IN] = nft_nat_ipv4_fn,
},
};

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