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 struct nf_nat_info *info;
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(*pskb)->frag_off & htons(IP_MF | IP_OFFSET)));
91 ct = nf_ct_get(*pskb, &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
97 /* Exception: ICMP redirect to new connection (not in
98 hash table yet). We must not let this through, in
99 case we're doing NAT to the same network. */
100 if (ip_hdr(*pskb)->protocol == IPPROTO_ICMP) {
101 struct icmphdr _hdr, *hp;
103 hp = skb_header_pointer(*pskb, ip_hdrlen(*pskb),
104 sizeof(_hdr), &_hdr);
106 hp->type == ICMP_REDIRECT)
112 /* Don't try to NAT if this packet is not conntracked */
113 if (ct == &nf_conntrack_untracked)
122 case IP_CT_RELATED+IP_CT_IS_REPLY:
123 if (ip_hdr(*pskb)->protocol == IPPROTO_ICMP) {
124 if (!nf_nat_icmp_reply_translation(ct, ctinfo,
130 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
134 /* Seen it before? This can happen for loopback, retrans,
135 or local packets.. */
136 if (!nf_nat_initialized(ct, maniptype)) {
139 if (unlikely(nf_ct_is_confirmed(ct)))
140 /* NAT module was loaded late */
141 ret = alloc_null_binding_confirmed(ct, info,
143 else if (hooknum == NF_IP_LOCAL_IN)
144 /* LOCAL_IN hook doesn't have a chain! */
145 ret = alloc_null_binding(ct, info, hooknum);
147 ret = nf_nat_rule_find(pskb, hooknum, in, out,
150 if (ret != NF_ACCEPT) {
154 DEBUGP("Already setup manip %s for ct %p\n",
155 maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
161 NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
162 ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
167 return nf_nat_packet(ct, ctinfo, hooknum, pskb);
171 nf_nat_in(unsigned int hooknum,
172 struct sk_buff **pskb,
173 const struct net_device *in,
174 const struct net_device *out,
175 int (*okfn)(struct sk_buff *))
178 __be32 daddr = ip_hdr(*pskb)->daddr;
180 ret = nf_nat_fn(hooknum, pskb, in, out, okfn);
181 if (ret != NF_DROP && ret != NF_STOLEN &&
182 daddr != ip_hdr(*pskb)->daddr) {
183 dst_release((*pskb)->dst);
190 nf_nat_out(unsigned int hooknum,
191 struct sk_buff **pskb,
192 const struct net_device *in,
193 const struct net_device *out,
194 int (*okfn)(struct sk_buff *))
198 enum ip_conntrack_info ctinfo;
202 /* root is playing with raw sockets. */
203 if ((*pskb)->len < sizeof(struct iphdr) ||
204 ip_hdrlen(*pskb) < sizeof(struct iphdr))
207 ret = nf_nat_fn(hooknum, pskb, in, out, okfn);
209 if (ret != NF_DROP && ret != NF_STOLEN &&
210 (ct = nf_ct_get(*pskb, &ctinfo)) != NULL) {
211 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
213 if (ct->tuplehash[dir].tuple.src.u3.ip !=
214 ct->tuplehash[!dir].tuple.dst.u3.ip
215 || ct->tuplehash[dir].tuple.src.u.all !=
216 ct->tuplehash[!dir].tuple.dst.u.all
218 return ip_xfrm_me_harder(pskb) == 0 ? ret : NF_DROP;
225 nf_nat_local_fn(unsigned int hooknum,
226 struct sk_buff **pskb,
227 const struct net_device *in,
228 const struct net_device *out,
229 int (*okfn)(struct sk_buff *))
232 enum ip_conntrack_info ctinfo;
235 /* root is playing with raw sockets. */
236 if ((*pskb)->len < sizeof(struct iphdr) ||
237 ip_hdrlen(*pskb) < sizeof(struct iphdr))
240 ret = nf_nat_fn(hooknum, pskb, in, out, okfn);
241 if (ret != NF_DROP && ret != NF_STOLEN &&
242 (ct = nf_ct_get(*pskb, &ctinfo)) != NULL) {
243 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
245 if (ct->tuplehash[dir].tuple.dst.u3.ip !=
246 ct->tuplehash[!dir].tuple.src.u3.ip) {
247 if (ip_route_me_harder(pskb, RTN_UNSPEC))
251 else if (ct->tuplehash[dir].tuple.dst.u.all !=
252 ct->tuplehash[!dir].tuple.src.u.all)
253 if (ip_xfrm_me_harder(pskb))
261 nf_nat_adjust(unsigned int hooknum,
262 struct sk_buff **pskb,
263 const struct net_device *in,
264 const struct net_device *out,
265 int (*okfn)(struct sk_buff *))
268 enum ip_conntrack_info ctinfo;
270 ct = nf_ct_get(*pskb, &ctinfo);
271 if (ct && test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
272 DEBUGP("nf_nat_standalone: adjusting sequence number\n");
273 if (!nf_nat_seq_adjust(pskb, ct, ctinfo))
279 /* We must be after connection tracking and before packet filtering. */
281 static struct nf_hook_ops nf_nat_ops[] = {
282 /* Before packet filtering, change destination */
285 .owner = THIS_MODULE,
287 .hooknum = NF_IP_PRE_ROUTING,
288 .priority = NF_IP_PRI_NAT_DST,
290 /* After packet filtering, change source */
293 .owner = THIS_MODULE,
295 .hooknum = NF_IP_POST_ROUTING,
296 .priority = NF_IP_PRI_NAT_SRC,
298 /* After conntrack, adjust sequence number */
300 .hook = nf_nat_adjust,
301 .owner = THIS_MODULE,
303 .hooknum = NF_IP_POST_ROUTING,
304 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
306 /* Before packet filtering, change destination */
308 .hook = nf_nat_local_fn,
309 .owner = THIS_MODULE,
311 .hooknum = NF_IP_LOCAL_OUT,
312 .priority = NF_IP_PRI_NAT_DST,
314 /* After packet filtering, change source */
317 .owner = THIS_MODULE,
319 .hooknum = NF_IP_LOCAL_IN,
320 .priority = NF_IP_PRI_NAT_SRC,
322 /* After conntrack, adjust sequence number */
324 .hook = nf_nat_adjust,
325 .owner = THIS_MODULE,
327 .hooknum = NF_IP_LOCAL_IN,
328 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
332 static int __init nf_nat_standalone_init(void)
338 size = ALIGN(sizeof(struct nf_conn), __alignof__(struct nf_conn_nat)) +
339 sizeof(struct nf_conn_nat);
340 ret = nf_conntrack_register_cache(NF_CT_F_NAT, "nf_nat:base", size);
342 printk(KERN_ERR "nf_nat_init: Unable to create slab cache\n");
346 size = ALIGN(size, __alignof__(struct nf_conn_help)) +
347 sizeof(struct nf_conn_help);
348 ret = nf_conntrack_register_cache(NF_CT_F_NAT|NF_CT_F_HELP,
349 "nf_nat:help", size);
351 printk(KERN_ERR "nf_nat_init: Unable to create slab cache\n");
352 goto cleanup_register_cache;
355 BUG_ON(ip_nat_decode_session != NULL);
356 ip_nat_decode_session = nat_decode_session;
358 ret = nf_nat_rule_init();
360 printk("nf_nat_init: can't setup rules.\n");
361 goto cleanup_decode_session;
363 ret = nf_register_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops));
365 printk("nf_nat_init: can't register hooks.\n");
366 goto cleanup_rule_init;
368 nf_nat_module_is_loaded = 1;
372 nf_nat_rule_cleanup();
373 cleanup_decode_session:
375 ip_nat_decode_session = NULL;
378 nf_conntrack_unregister_cache(NF_CT_F_NAT|NF_CT_F_HELP);
379 cleanup_register_cache:
380 nf_conntrack_unregister_cache(NF_CT_F_NAT);
384 static void __exit nf_nat_standalone_fini(void)
386 nf_unregister_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops));
387 nf_nat_rule_cleanup();
388 nf_nat_module_is_loaded = 0;
390 ip_nat_decode_session = NULL;
393 /* Conntrack caches are unregistered in nf_conntrack_cleanup */
396 module_init(nf_nat_standalone_init);
397 module_exit(nf_nat_standalone_fini);
399 MODULE_LICENSE("GPL");
400 MODULE_ALIAS("ip_nat");