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_nat.h>
23 #include <net/netfilter/nf_nat_rule.h>
24 #include <net/netfilter/nf_nat_protocol.h>
25 #include <net/netfilter/nf_nat_core.h>
26 #include <net/netfilter/nf_nat_helper.h>
27 #include <linux/netfilter_ipv4/ip_tables.h>
32 #define DEBUGP(format, args...)
36 static void nat_decode_session(struct sk_buff
*skb
, struct flowi
*fl
)
39 struct nf_conntrack_tuple
*t
;
40 enum ip_conntrack_info ctinfo
;
41 enum ip_conntrack_dir dir
;
42 unsigned long statusbit
;
44 ct
= nf_ct_get(skb
, &ctinfo
);
47 dir
= CTINFO2DIR(ctinfo
);
48 t
= &ct
->tuplehash
[dir
].tuple
;
50 if (dir
== IP_CT_DIR_ORIGINAL
)
51 statusbit
= IPS_DST_NAT
;
53 statusbit
= IPS_SRC_NAT
;
55 if (ct
->status
& statusbit
) {
56 fl
->fl4_dst
= t
->dst
.u3
.ip
;
57 if (t
->dst
.protonum
== IPPROTO_TCP
||
58 t
->dst
.protonum
== IPPROTO_UDP
)
59 fl
->fl_ip_dport
= t
->dst
.u
.tcp
.port
;
62 statusbit
^= IPS_NAT_MASK
;
64 if (ct
->status
& statusbit
) {
65 fl
->fl4_src
= t
->src
.u3
.ip
;
66 if (t
->dst
.protonum
== IPPROTO_TCP
||
67 t
->dst
.protonum
== IPPROTO_UDP
)
68 fl
->fl_ip_sport
= t
->src
.u
.tcp
.port
;
74 nf_nat_fn(unsigned int hooknum
,
75 struct sk_buff
**pskb
,
76 const struct net_device
*in
,
77 const struct net_device
*out
,
78 int (*okfn
)(struct sk_buff
*))
81 enum ip_conntrack_info ctinfo
;
82 struct nf_conn_nat
*nat
;
83 /* maniptype == SRC for postrouting. */
84 enum nf_nat_manip_type maniptype
= HOOK2MANIP(hooknum
);
86 /* We never see fragments: conntrack defrags on pre-routing
87 and local-out, and nf_nat_out protects post-routing. */
88 NF_CT_ASSERT(!(ip_hdr(*pskb
)->frag_off
& htons(IP_MF
| IP_OFFSET
)));
90 ct
= nf_ct_get(*pskb
, &ctinfo
);
91 /* Can't track? It's not due to stress, or conntrack would
92 have dropped it. Hence it's the user's responsibilty to
93 packet filter it out, or implement conntrack/NAT for that
96 /* Exception: ICMP redirect to new connection (not in
97 hash table yet). We must not let this through, in
98 case we're doing NAT to the same network. */
99 if (ip_hdr(*pskb
)->protocol
== IPPROTO_ICMP
) {
100 struct icmphdr _hdr
, *hp
;
102 hp
= skb_header_pointer(*pskb
, ip_hdrlen(*pskb
),
103 sizeof(_hdr
), &_hdr
);
105 hp
->type
== ICMP_REDIRECT
)
111 /* Don't try to NAT if this packet is not conntracked */
112 if (ct
== &nf_conntrack_untracked
)
121 case IP_CT_RELATED
+IP_CT_IS_REPLY
:
122 if (ip_hdr(*pskb
)->protocol
== IPPROTO_ICMP
) {
123 if (!nf_nat_icmp_reply_translation(ct
, ctinfo
,
129 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
132 /* Seen it before? This can happen for loopback, retrans,
133 or local packets.. */
134 if (!nf_nat_initialized(ct
, maniptype
)) {
137 if (unlikely(nf_ct_is_confirmed(ct
)))
138 /* NAT module was loaded late */
139 ret
= alloc_null_binding_confirmed(ct
, hooknum
);
140 else if (hooknum
== NF_IP_LOCAL_IN
)
141 /* LOCAL_IN hook doesn't have a chain! */
142 ret
= alloc_null_binding(ct
, hooknum
);
144 ret
= nf_nat_rule_find(pskb
, hooknum
, in
, out
,
147 if (ret
!= NF_ACCEPT
) {
151 DEBUGP("Already setup manip %s for ct %p\n",
152 maniptype
== IP_NAT_MANIP_SRC
? "SRC" : "DST",
158 NF_CT_ASSERT(ctinfo
== IP_CT_ESTABLISHED
||
159 ctinfo
== (IP_CT_ESTABLISHED
+IP_CT_IS_REPLY
));
162 return nf_nat_packet(ct
, ctinfo
, hooknum
, pskb
);
166 nf_nat_in(unsigned int hooknum
,
167 struct sk_buff
**pskb
,
168 const struct net_device
*in
,
169 const struct net_device
*out
,
170 int (*okfn
)(struct sk_buff
*))
173 __be32 daddr
= ip_hdr(*pskb
)->daddr
;
175 ret
= nf_nat_fn(hooknum
, pskb
, in
, out
, okfn
);
176 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
&&
177 daddr
!= ip_hdr(*pskb
)->daddr
) {
178 dst_release((*pskb
)->dst
);
185 nf_nat_out(unsigned int hooknum
,
186 struct sk_buff
**pskb
,
187 const struct net_device
*in
,
188 const struct net_device
*out
,
189 int (*okfn
)(struct sk_buff
*))
193 enum ip_conntrack_info ctinfo
;
197 /* root is playing with raw sockets. */
198 if ((*pskb
)->len
< sizeof(struct iphdr
) ||
199 ip_hdrlen(*pskb
) < sizeof(struct iphdr
))
202 ret
= nf_nat_fn(hooknum
, pskb
, in
, out
, okfn
);
204 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
&&
205 (ct
= nf_ct_get(*pskb
, &ctinfo
)) != NULL
) {
206 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
208 if (ct
->tuplehash
[dir
].tuple
.src
.u3
.ip
!=
209 ct
->tuplehash
[!dir
].tuple
.dst
.u3
.ip
210 || ct
->tuplehash
[dir
].tuple
.src
.u
.all
!=
211 ct
->tuplehash
[!dir
].tuple
.dst
.u
.all
213 return ip_xfrm_me_harder(pskb
) == 0 ? ret
: NF_DROP
;
220 nf_nat_local_fn(unsigned int hooknum
,
221 struct sk_buff
**pskb
,
222 const struct net_device
*in
,
223 const struct net_device
*out
,
224 int (*okfn
)(struct sk_buff
*))
227 enum ip_conntrack_info ctinfo
;
230 /* root is playing with raw sockets. */
231 if ((*pskb
)->len
< sizeof(struct iphdr
) ||
232 ip_hdrlen(*pskb
) < sizeof(struct iphdr
))
235 ret
= nf_nat_fn(hooknum
, pskb
, in
, out
, okfn
);
236 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
&&
237 (ct
= nf_ct_get(*pskb
, &ctinfo
)) != NULL
) {
238 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
240 if (ct
->tuplehash
[dir
].tuple
.dst
.u3
.ip
!=
241 ct
->tuplehash
[!dir
].tuple
.src
.u3
.ip
) {
242 if (ip_route_me_harder(pskb
, RTN_UNSPEC
))
246 else if (ct
->tuplehash
[dir
].tuple
.dst
.u
.all
!=
247 ct
->tuplehash
[!dir
].tuple
.src
.u
.all
)
248 if (ip_xfrm_me_harder(pskb
))
256 nf_nat_adjust(unsigned int hooknum
,
257 struct sk_buff
**pskb
,
258 const struct net_device
*in
,
259 const struct net_device
*out
,
260 int (*okfn
)(struct sk_buff
*))
263 enum ip_conntrack_info ctinfo
;
265 ct
= nf_ct_get(*pskb
, &ctinfo
);
266 if (ct
&& test_bit(IPS_SEQ_ADJUST_BIT
, &ct
->status
)) {
267 DEBUGP("nf_nat_standalone: adjusting sequence number\n");
268 if (!nf_nat_seq_adjust(pskb
, ct
, ctinfo
))
274 /* We must be after connection tracking and before packet filtering. */
276 static struct nf_hook_ops nf_nat_ops
[] = {
277 /* Before packet filtering, change destination */
280 .owner
= THIS_MODULE
,
282 .hooknum
= NF_IP_PRE_ROUTING
,
283 .priority
= NF_IP_PRI_NAT_DST
,
285 /* After packet filtering, change source */
288 .owner
= THIS_MODULE
,
290 .hooknum
= NF_IP_POST_ROUTING
,
291 .priority
= NF_IP_PRI_NAT_SRC
,
293 /* After conntrack, adjust sequence number */
295 .hook
= nf_nat_adjust
,
296 .owner
= THIS_MODULE
,
298 .hooknum
= NF_IP_POST_ROUTING
,
299 .priority
= NF_IP_PRI_NAT_SEQ_ADJUST
,
301 /* Before packet filtering, change destination */
303 .hook
= nf_nat_local_fn
,
304 .owner
= THIS_MODULE
,
306 .hooknum
= NF_IP_LOCAL_OUT
,
307 .priority
= NF_IP_PRI_NAT_DST
,
309 /* After packet filtering, change source */
312 .owner
= THIS_MODULE
,
314 .hooknum
= NF_IP_LOCAL_IN
,
315 .priority
= NF_IP_PRI_NAT_SRC
,
317 /* After conntrack, adjust sequence number */
319 .hook
= nf_nat_adjust
,
320 .owner
= THIS_MODULE
,
322 .hooknum
= NF_IP_LOCAL_IN
,
323 .priority
= NF_IP_PRI_NAT_SEQ_ADJUST
,
327 static int __init
nf_nat_standalone_init(void)
333 size
= ALIGN(sizeof(struct nf_conn
), __alignof__(struct nf_conn_nat
)) +
334 sizeof(struct nf_conn_nat
);
335 ret
= nf_conntrack_register_cache(NF_CT_F_NAT
, "nf_nat:base", size
);
337 printk(KERN_ERR
"nf_nat_init: Unable to create slab cache\n");
341 size
= ALIGN(size
, __alignof__(struct nf_conn_help
)) +
342 sizeof(struct nf_conn_help
);
343 ret
= nf_conntrack_register_cache(NF_CT_F_NAT
|NF_CT_F_HELP
,
344 "nf_nat:help", size
);
346 printk(KERN_ERR
"nf_nat_init: Unable to create slab cache\n");
347 goto cleanup_register_cache
;
350 BUG_ON(ip_nat_decode_session
!= NULL
);
351 ip_nat_decode_session
= nat_decode_session
;
353 ret
= nf_nat_rule_init();
355 printk("nf_nat_init: can't setup rules.\n");
356 goto cleanup_decode_session
;
358 ret
= nf_register_hooks(nf_nat_ops
, ARRAY_SIZE(nf_nat_ops
));
360 printk("nf_nat_init: can't register hooks.\n");
361 goto cleanup_rule_init
;
363 nf_nat_module_is_loaded
= 1;
367 nf_nat_rule_cleanup();
368 cleanup_decode_session
:
370 ip_nat_decode_session
= NULL
;
373 nf_conntrack_unregister_cache(NF_CT_F_NAT
|NF_CT_F_HELP
);
374 cleanup_register_cache
:
375 nf_conntrack_unregister_cache(NF_CT_F_NAT
);
379 static void __exit
nf_nat_standalone_fini(void)
381 nf_unregister_hooks(nf_nat_ops
, ARRAY_SIZE(nf_nat_ops
));
382 nf_nat_rule_cleanup();
383 nf_nat_module_is_loaded
= 0;
385 ip_nat_decode_session
= NULL
;
388 /* Conntrack caches are unregistered in nf_conntrack_cleanup */
391 module_init(nf_nat_standalone_init
);
392 module_exit(nf_nat_standalone_fini
);
394 MODULE_LICENSE("GPL");
395 MODULE_ALIAS("ip_nat");