1 /* This file contains all the functions required for the standalone
4 These are not required by the compatibility layer.
7 /* (C) 1999-2001 Paul `Rusty' Russell
8 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
16 * 23 Apr 2001: Harald Welte <laforge@gnumonks.org>
17 * - new API and handling of conntrack/nat helpers
18 * - now capable of multiple expectations for one master
21 #include <linux/config.h>
22 #include <linux/types.h>
23 #include <linux/icmp.h>
25 #include <linux/netfilter.h>
26 #include <linux/netfilter_ipv4.h>
27 #include <linux/module.h>
28 #include <linux/skbuff.h>
29 #include <linux/proc_fs.h>
31 #include <net/checksum.h>
32 #include <linux/spinlock.h>
34 #define ASSERT_READ_LOCK(x)
35 #define ASSERT_WRITE_LOCK(x)
37 #include <linux/netfilter_ipv4/ip_nat.h>
38 #include <linux/netfilter_ipv4/ip_nat_rule.h>
39 #include <linux/netfilter_ipv4/ip_nat_protocol.h>
40 #include <linux/netfilter_ipv4/ip_nat_core.h>
41 #include <linux/netfilter_ipv4/ip_nat_helper.h>
42 #include <linux/netfilter_ipv4/ip_tables.h>
43 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
44 #include <linux/netfilter_ipv4/listhelp.h>
49 #define DEBUGP(format, args...)
52 #define HOOKNAME(hooknum) ((hooknum) == NF_IP_POST_ROUTING ? "POST_ROUTING" \
53 : ((hooknum) == NF_IP_PRE_ROUTING ? "PRE_ROUTING" \
54 : ((hooknum) == NF_IP_LOCAL_OUT ? "LOCAL_OUT" \
55 : ((hooknum) == NF_IP_LOCAL_IN ? "LOCAL_IN" \
59 static void nat_decode_session(struct sk_buff
*skb
, struct flowi
*fl
)
61 struct ip_conntrack
*ct
;
62 struct ip_conntrack_tuple
*t
;
63 enum ip_conntrack_info ctinfo
;
64 enum ip_conntrack_dir dir
;
65 unsigned long statusbit
;
67 ct
= ip_conntrack_get(skb
, &ctinfo
);
70 dir
= CTINFO2DIR(ctinfo
);
71 t
= &ct
->tuplehash
[dir
].tuple
;
73 if (dir
== IP_CT_DIR_ORIGINAL
)
74 statusbit
= IPS_DST_NAT
;
76 statusbit
= IPS_SRC_NAT
;
78 if (ct
->status
& statusbit
) {
79 fl
->fl4_dst
= t
->dst
.ip
;
80 if (t
->dst
.protonum
== IPPROTO_TCP
||
81 t
->dst
.protonum
== IPPROTO_UDP
)
82 fl
->fl_ip_dport
= t
->dst
.u
.tcp
.port
;
85 statusbit
^= IPS_NAT_MASK
;
87 if (ct
->status
& statusbit
) {
88 fl
->fl4_src
= t
->src
.ip
;
89 if (t
->dst
.protonum
== IPPROTO_TCP
||
90 t
->dst
.protonum
== IPPROTO_UDP
)
91 fl
->fl_ip_sport
= t
->src
.u
.tcp
.port
;
97 ip_nat_fn(unsigned int hooknum
,
98 struct sk_buff
**pskb
,
99 const struct net_device
*in
,
100 const struct net_device
*out
,
101 int (*okfn
)(struct sk_buff
*))
103 struct ip_conntrack
*ct
;
104 enum ip_conntrack_info ctinfo
;
105 struct ip_nat_info
*info
;
106 /* maniptype == SRC for postrouting. */
107 enum ip_nat_manip_type maniptype
= HOOK2MANIP(hooknum
);
109 /* We never see fragments: conntrack defrags on pre-routing
110 and local-out, and ip_nat_out protects post-routing. */
111 IP_NF_ASSERT(!((*pskb
)->nh
.iph
->frag_off
112 & htons(IP_MF
|IP_OFFSET
)));
114 /* If we had a hardware checksum before, it's now invalid */
115 if ((*pskb
)->ip_summed
== CHECKSUM_HW
)
116 if (skb_checksum_help(*pskb
, (out
== NULL
)))
119 ct
= ip_conntrack_get(*pskb
, &ctinfo
);
120 /* Can't track? It's not due to stress, or conntrack would
121 have dropped it. Hence it's the user's responsibilty to
122 packet filter it out, or implement conntrack/NAT for that
125 /* Exception: ICMP redirect to new connection (not in
126 hash table yet). We must not let this through, in
127 case we're doing NAT to the same network. */
128 if ((*pskb
)->nh
.iph
->protocol
== IPPROTO_ICMP
) {
129 struct icmphdr _hdr
, *hp
;
131 hp
= skb_header_pointer(*pskb
,
132 (*pskb
)->nh
.iph
->ihl
*4,
133 sizeof(_hdr
), &_hdr
);
135 hp
->type
== ICMP_REDIRECT
)
141 /* Don't try to NAT if this packet is not conntracked */
142 if (ct
== &ip_conntrack_untracked
)
147 case IP_CT_RELATED
+IP_CT_IS_REPLY
:
148 if ((*pskb
)->nh
.iph
->protocol
== IPPROTO_ICMP
) {
149 if (!ip_nat_icmp_reply_translation(pskb
, ct
, maniptype
,
155 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
157 info
= &ct
->nat
.info
;
159 /* Seen it before? This can happen for loopback, retrans,
160 or local packets.. */
161 if (!ip_nat_initialized(ct
, maniptype
)) {
164 if (unlikely(is_confirmed(ct
)))
165 /* NAT module was loaded late */
166 ret
= alloc_null_binding_confirmed(ct
, info
,
168 else if (hooknum
== NF_IP_LOCAL_IN
)
169 /* LOCAL_IN hook doesn't have a chain! */
170 ret
= alloc_null_binding(ct
, info
, hooknum
);
172 ret
= ip_nat_rule_find(pskb
, hooknum
,
176 if (ret
!= NF_ACCEPT
) {
180 DEBUGP("Already setup manip %s for ct %p\n",
181 maniptype
== IP_NAT_MANIP_SRC
? "SRC" : "DST",
187 IP_NF_ASSERT(ctinfo
== IP_CT_ESTABLISHED
188 || ctinfo
== (IP_CT_ESTABLISHED
+IP_CT_IS_REPLY
));
189 info
= &ct
->nat
.info
;
193 return ip_nat_packet(ct
, ctinfo
, hooknum
, pskb
);
197 ip_nat_in(unsigned int hooknum
,
198 struct sk_buff
**pskb
,
199 const struct net_device
*in
,
200 const struct net_device
*out
,
201 int (*okfn
)(struct sk_buff
*))
204 u_int32_t daddr
= (*pskb
)->nh
.iph
->daddr
;
206 ret
= ip_nat_fn(hooknum
, pskb
, in
, out
, okfn
);
207 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
208 && daddr
!= (*pskb
)->nh
.iph
->daddr
) {
209 dst_release((*pskb
)->dst
);
216 ip_nat_out(unsigned int hooknum
,
217 struct sk_buff
**pskb
,
218 const struct net_device
*in
,
219 const struct net_device
*out
,
220 int (*okfn
)(struct sk_buff
*))
222 struct ip_conntrack
*ct
;
223 enum ip_conntrack_info ctinfo
;
226 /* root is playing with raw sockets. */
227 if ((*pskb
)->len
< sizeof(struct iphdr
)
228 || (*pskb
)->nh
.iph
->ihl
* 4 < sizeof(struct iphdr
))
231 ret
= ip_nat_fn(hooknum
, pskb
, in
, out
, okfn
);
233 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
234 && (ct
= ip_conntrack_get(*pskb
, &ctinfo
)) != NULL
) {
235 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
237 if (ct
->tuplehash
[dir
].tuple
.src
.ip
!=
238 ct
->tuplehash
[!dir
].tuple
.dst
.ip
239 || ct
->tuplehash
[dir
].tuple
.src
.u
.all
!=
240 ct
->tuplehash
[!dir
].tuple
.dst
.u
.all
242 return ip_xfrm_me_harder(pskb
) == 0 ? ret
: NF_DROP
;
249 ip_nat_local_fn(unsigned int hooknum
,
250 struct sk_buff
**pskb
,
251 const struct net_device
*in
,
252 const struct net_device
*out
,
253 int (*okfn
)(struct sk_buff
*))
255 struct ip_conntrack
*ct
;
256 enum ip_conntrack_info ctinfo
;
259 /* root is playing with raw sockets. */
260 if ((*pskb
)->len
< sizeof(struct iphdr
)
261 || (*pskb
)->nh
.iph
->ihl
* 4 < sizeof(struct iphdr
))
264 ret
= ip_nat_fn(hooknum
, pskb
, in
, out
, okfn
);
265 if (ret
!= NF_DROP
&& ret
!= NF_STOLEN
266 && (ct
= ip_conntrack_get(*pskb
, &ctinfo
)) != NULL
) {
267 enum ip_conntrack_dir dir
= CTINFO2DIR(ctinfo
);
269 if (ct
->tuplehash
[dir
].tuple
.dst
.ip
!=
270 ct
->tuplehash
[!dir
].tuple
.src
.ip
272 || ct
->tuplehash
[dir
].tuple
.dst
.u
.all
!=
273 ct
->tuplehash
[!dir
].tuple
.src
.u
.all
276 return ip_route_me_harder(pskb
) == 0 ? ret
: NF_DROP
;
282 ip_nat_adjust(unsigned int hooknum
,
283 struct sk_buff
**pskb
,
284 const struct net_device
*in
,
285 const struct net_device
*out
,
286 int (*okfn
)(struct sk_buff
*))
288 struct ip_conntrack
*ct
;
289 enum ip_conntrack_info ctinfo
;
291 ct
= ip_conntrack_get(*pskb
, &ctinfo
);
292 if (ct
&& test_bit(IPS_SEQ_ADJUST_BIT
, &ct
->status
)) {
293 DEBUGP("ip_nat_standalone: adjusting sequence number\n");
294 if (!ip_nat_seq_adjust(pskb
, ct
, ctinfo
))
300 /* We must be after connection tracking and before packet filtering. */
302 /* Before packet filtering, change destination */
303 static struct nf_hook_ops ip_nat_in_ops
= {
305 .owner
= THIS_MODULE
,
307 .hooknum
= NF_IP_PRE_ROUTING
,
308 .priority
= NF_IP_PRI_NAT_DST
,
311 /* After packet filtering, change source */
312 static struct nf_hook_ops ip_nat_out_ops
= {
314 .owner
= THIS_MODULE
,
316 .hooknum
= NF_IP_POST_ROUTING
,
317 .priority
= NF_IP_PRI_NAT_SRC
,
320 /* After conntrack, adjust sequence number */
321 static struct nf_hook_ops ip_nat_adjust_out_ops
= {
322 .hook
= ip_nat_adjust
,
323 .owner
= THIS_MODULE
,
325 .hooknum
= NF_IP_POST_ROUTING
,
326 .priority
= NF_IP_PRI_NAT_SEQ_ADJUST
,
329 /* Before packet filtering, change destination */
330 static struct nf_hook_ops ip_nat_local_out_ops
= {
331 .hook
= ip_nat_local_fn
,
332 .owner
= THIS_MODULE
,
334 .hooknum
= NF_IP_LOCAL_OUT
,
335 .priority
= NF_IP_PRI_NAT_DST
,
338 /* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
339 static struct nf_hook_ops ip_nat_local_in_ops
= {
341 .owner
= THIS_MODULE
,
343 .hooknum
= NF_IP_LOCAL_IN
,
344 .priority
= NF_IP_PRI_NAT_SRC
,
347 /* After conntrack, adjust sequence number */
348 static struct nf_hook_ops ip_nat_adjust_in_ops
= {
349 .hook
= ip_nat_adjust
,
350 .owner
= THIS_MODULE
,
352 .hooknum
= NF_IP_LOCAL_IN
,
353 .priority
= NF_IP_PRI_NAT_SEQ_ADJUST
,
357 static int init_or_cleanup(int init
)
363 if (!init
) goto cleanup
;
366 BUG_ON(ip_nat_decode_session
!= NULL
);
367 ip_nat_decode_session
= nat_decode_session
;
369 ret
= ip_nat_rule_init();
371 printk("ip_nat_init: can't setup rules.\n");
372 goto cleanup_decode_session
;
374 ret
= nf_register_hook(&ip_nat_in_ops
);
376 printk("ip_nat_init: can't register in hook.\n");
377 goto cleanup_rule_init
;
379 ret
= nf_register_hook(&ip_nat_out_ops
);
381 printk("ip_nat_init: can't register out hook.\n");
384 ret
= nf_register_hook(&ip_nat_adjust_in_ops
);
386 printk("ip_nat_init: can't register adjust in hook.\n");
389 ret
= nf_register_hook(&ip_nat_adjust_out_ops
);
391 printk("ip_nat_init: can't register adjust out hook.\n");
392 goto cleanup_adjustin_ops
;
394 ret
= nf_register_hook(&ip_nat_local_out_ops
);
396 printk("ip_nat_init: can't register local out hook.\n");
397 goto cleanup_adjustout_ops
;;
399 ret
= nf_register_hook(&ip_nat_local_in_ops
);
401 printk("ip_nat_init: can't register local in hook.\n");
402 goto cleanup_localoutops
;
407 nf_unregister_hook(&ip_nat_local_in_ops
);
409 nf_unregister_hook(&ip_nat_local_out_ops
);
410 cleanup_adjustout_ops
:
411 nf_unregister_hook(&ip_nat_adjust_out_ops
);
412 cleanup_adjustin_ops
:
413 nf_unregister_hook(&ip_nat_adjust_in_ops
);
415 nf_unregister_hook(&ip_nat_out_ops
);
417 nf_unregister_hook(&ip_nat_in_ops
);
419 ip_nat_rule_cleanup();
420 cleanup_decode_session
:
422 ip_nat_decode_session
= NULL
;
428 static int __init
init(void)
430 return init_or_cleanup(1);
433 static void __exit
fini(void)
441 MODULE_LICENSE("GPL");