1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
8 #include <linux/types.h>
9 #include <linux/icmp.h>
11 #include <linux/netfilter.h>
12 #include <linux/netfilter_ipv4.h>
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/proc_fs.h>
17 #include <net/checksum.h>
18 #include <linux/spinlock.h>
20 #include <net/netfilter/nf_conntrack.h>
21 #include <net/netfilter/nf_conntrack_core.h>
22 #include <net/netfilter/nf_conntrack_extend.h>
23 #include <net/netfilter/nf_nat.h>
24 #include <net/netfilter/nf_nat_rule.h>
25 #include <net/netfilter/nf_nat_protocol.h>
26 #include <net/netfilter/nf_nat_core.h>
27 #include <net/netfilter/nf_nat_helper.h>
28 #include <linux/netfilter_ipv4/ip_tables.h>
31 static void nat_decode_session(struct sk_buff
*skb
, struct flowi
*fl
)
33 const struct nf_conn
*ct
;
34 const struct nf_conntrack_tuple
*t
;
35 enum ip_conntrack_info ctinfo
;
36 enum ip_conntrack_dir dir
;
37 unsigned long statusbit
;
39 ct
= nf_ct_get(skb
, &ctinfo
);
42 dir
= CTINFO2DIR(ctinfo
);
43 t
= &ct
->tuplehash
[dir
].tuple
;
45 if (dir
== IP_CT_DIR_ORIGINAL
)
46 statusbit
= IPS_DST_NAT
;
48 statusbit
= IPS_SRC_NAT
;
50 if (ct
->status
& statusbit
) {
51 fl
->fl4_dst
= t
->dst
.u3
.ip
;
52 if (t
->dst
.protonum
== IPPROTO_TCP
||
53 t
->dst
.protonum
== IPPROTO_UDP
||
54 t
->dst
.protonum
== IPPROTO_UDPLITE
||
55 t
->dst
.protonum
== IPPROTO_DCCP
||
56 t
->dst
.protonum
== IPPROTO_SCTP
)
57 fl
->fl_ip_dport
= t
->dst
.u
.tcp
.port
;
60 statusbit
^= IPS_NAT_MASK
;
62 if (ct
->status
& statusbit
) {
63 fl
->fl4_src
= t
->src
.u3
.ip
;
64 if (t
->dst
.protonum
== IPPROTO_TCP
||
65 t
->dst
.protonum
== IPPROTO_UDP
||
66 t
->dst
.protonum
== IPPROTO_UDPLITE
||
67 t
->dst
.protonum
== IPPROTO_DCCP
||
68 t
->dst
.protonum
== IPPROTO_SCTP
)
69 fl
->fl_ip_sport
= t
->src
.u
.tcp
.port
;
75 nf_nat_fn(unsigned int hooknum
,
77 const struct net_device
*in
,
78 const struct net_device
*out
,
79 int (*okfn
)(struct sk_buff
*))
82 enum ip_conntrack_info ctinfo
;
83 struct nf_conn_nat
*nat
;
84 /* maniptype == SRC for postrouting. */
85 enum nf_nat_manip_type maniptype
= HOOK2MANIP(hooknum
);
87 /* We never see fragments: conntrack defrags on pre-routing
88 and local-out, and nf_nat_out protects post-routing. */
89 NF_CT_ASSERT(!(ip_hdr(skb
)->frag_off
& htons(IP_MF
| IP_OFFSET
)));
91 ct
= nf_ct_get(skb
, &ctinfo
);
92 /* Can't track? It's not due to stress, or conntrack would
93 have dropped it. Hence it's the user's responsibilty to
94 packet filter it out, or implement conntrack/NAT for that
99 /* Don't try to NAT if this packet is not conntracked */
100 if (ct
== &nf_conntrack_untracked
)
105 /* NAT module was loaded late. */
106 if (nf_ct_is_confirmed(ct
))
108 nat
= nf_ct_ext_add(ct
, NF_CT_EXT_NAT
, GFP_ATOMIC
);
110 pr_debug("failed to add NAT extension\n");
117 case IP_CT_RELATED
+IP_CT_IS_REPLY
:
118 if (ip_hdr(skb
)->protocol
== IPPROTO_ICMP
) {
119 if (!nf_nat_icmp_reply_translation(ct
, ctinfo
,
125 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
128 /* Seen it before? This can happen for loopback, retrans,
129 or local packets.. */
130 if (!nf_nat_initialized(ct
, maniptype
)) {
133 if (hooknum
== NF_INET_LOCAL_IN
)
134 /* LOCAL_IN hook doesn't have a chain! */
135 ret
= alloc_null_binding(ct
, hooknum
);
137 ret
= nf_nat_rule_find(skb
, hooknum
, in
, out
,
140 if (ret
!= NF_ACCEPT
) {
144 pr_debug("Already setup manip %s for ct %p\n",
145 maniptype
== IP_NAT_MANIP_SRC
? "SRC" : "DST",
151 NF_CT_ASSERT(ctinfo
== IP_CT_ESTABLISHED
||
152 ctinfo
== (IP_CT_ESTABLISHED
+IP_CT_IS_REPLY
));
155 return nf_nat_packet(ct
, ctinfo
, hooknum
, skb
);
159 nf_nat_in(unsigned int hooknum
,
161 const struct net_device
*in
,
162 const struct net_device
*out
,
163 int (*okfn
)(struct sk_buff
*))
166 __be32 daddr
= ip_hdr(skb
)->daddr
;
168 ret
= nf_nat_fn(hooknum
, skb
, in
, out
, okfn
);
169 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
&&
170 daddr
!= ip_hdr(skb
)->daddr
) {
171 dst_release(skb
->dst
);
178 nf_nat_out(unsigned int hooknum
,
180 const struct net_device
*in
,
181 const struct net_device
*out
,
182 int (*okfn
)(struct sk_buff
*))
185 const struct nf_conn
*ct
;
186 enum ip_conntrack_info ctinfo
;
190 /* root is playing with raw sockets. */
191 if (skb
->len
< sizeof(struct iphdr
) ||
192 ip_hdrlen(skb
) < sizeof(struct iphdr
))
195 ret
= nf_nat_fn(hooknum
, skb
, in
, out
, okfn
);
197 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
&&
198 (ct
= nf_ct_get(skb
, &ctinfo
)) != NULL
) {
199 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
201 if (ct
->tuplehash
[dir
].tuple
.src
.u3
.ip
!=
202 ct
->tuplehash
[!dir
].tuple
.dst
.u3
.ip
203 || ct
->tuplehash
[dir
].tuple
.src
.u
.all
!=
204 ct
->tuplehash
[!dir
].tuple
.dst
.u
.all
206 return ip_xfrm_me_harder(skb
) == 0 ? ret
: NF_DROP
;
213 nf_nat_local_fn(unsigned int hooknum
,
215 const struct net_device
*in
,
216 const struct net_device
*out
,
217 int (*okfn
)(struct sk_buff
*))
219 const struct nf_conn
*ct
;
220 enum ip_conntrack_info ctinfo
;
223 /* root is playing with raw sockets. */
224 if (skb
->len
< sizeof(struct iphdr
) ||
225 ip_hdrlen(skb
) < sizeof(struct iphdr
))
228 ret
= nf_nat_fn(hooknum
, skb
, in
, out
, okfn
);
229 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
&&
230 (ct
= nf_ct_get(skb
, &ctinfo
)) != NULL
) {
231 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
233 if (ct
->tuplehash
[dir
].tuple
.dst
.u3
.ip
!=
234 ct
->tuplehash
[!dir
].tuple
.src
.u3
.ip
) {
235 if (ip_route_me_harder(skb
, RTN_UNSPEC
))
239 else if (ct
->tuplehash
[dir
].tuple
.dst
.u
.all
!=
240 ct
->tuplehash
[!dir
].tuple
.src
.u
.all
)
241 if (ip_xfrm_me_harder(skb
))
248 /* We must be after connection tracking and before packet filtering. */
250 static struct nf_hook_ops nf_nat_ops
[] __read_mostly
= {
251 /* Before packet filtering, change destination */
254 .owner
= THIS_MODULE
,
256 .hooknum
= NF_INET_PRE_ROUTING
,
257 .priority
= NF_IP_PRI_NAT_DST
,
259 /* After packet filtering, change source */
262 .owner
= THIS_MODULE
,
264 .hooknum
= NF_INET_POST_ROUTING
,
265 .priority
= NF_IP_PRI_NAT_SRC
,
267 /* Before packet filtering, change destination */
269 .hook
= nf_nat_local_fn
,
270 .owner
= THIS_MODULE
,
272 .hooknum
= NF_INET_LOCAL_OUT
,
273 .priority
= NF_IP_PRI_NAT_DST
,
275 /* After packet filtering, change source */
278 .owner
= THIS_MODULE
,
280 .hooknum
= NF_INET_LOCAL_IN
,
281 .priority
= NF_IP_PRI_NAT_SRC
,
285 static int __init
nf_nat_standalone_init(void)
289 need_ipv4_conntrack();
292 BUG_ON(ip_nat_decode_session
!= NULL
);
293 rcu_assign_pointer(ip_nat_decode_session
, nat_decode_session
);
295 ret
= nf_nat_rule_init();
297 printk("nf_nat_init: can't setup rules.\n");
298 goto cleanup_decode_session
;
300 ret
= nf_register_hooks(nf_nat_ops
, ARRAY_SIZE(nf_nat_ops
));
302 printk("nf_nat_init: can't register hooks.\n");
303 goto cleanup_rule_init
;
308 nf_nat_rule_cleanup();
309 cleanup_decode_session
:
311 rcu_assign_pointer(ip_nat_decode_session
, NULL
);
317 static void __exit
nf_nat_standalone_fini(void)
319 nf_unregister_hooks(nf_nat_ops
, ARRAY_SIZE(nf_nat_ops
));
320 nf_nat_rule_cleanup();
322 rcu_assign_pointer(ip_nat_decode_session
, NULL
);
325 /* Conntrack caches are unregistered in nf_conntrack_cleanup */
328 module_init(nf_nat_standalone_init
);
329 module_exit(nf_nat_standalone_fini
);
331 MODULE_LICENSE("GPL");
332 MODULE_ALIAS("ip_nat");