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/types.h>
22 #include <linux/icmp.h>
24 #include <linux/netfilter.h>
25 #include <linux/netfilter_ipv4.h>
26 #include <linux/module.h>
27 #include <linux/skbuff.h>
28 #include <linux/proc_fs.h>
30 #include <net/checksum.h>
31 #include <linux/spinlock.h>
33 #include <linux/netfilter_ipv4/ip_nat.h>
34 #include <linux/netfilter_ipv4/ip_nat_rule.h>
35 #include <linux/netfilter_ipv4/ip_nat_protocol.h>
36 #include <linux/netfilter_ipv4/ip_nat_core.h>
37 #include <linux/netfilter_ipv4/ip_nat_helper.h>
38 #include <linux/netfilter_ipv4/ip_tables.h>
39 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
44 #define DEBUGP(format, args...)
48 static void nat_decode_session(struct sk_buff *skb, struct flowi *fl)
50 struct ip_conntrack *ct;
51 struct ip_conntrack_tuple *t;
52 enum ip_conntrack_info ctinfo;
53 enum ip_conntrack_dir dir;
54 unsigned long statusbit;
56 ct = ip_conntrack_get(skb, &ctinfo);
59 dir = CTINFO2DIR(ctinfo);
60 t = &ct->tuplehash[dir].tuple;
62 if (dir == IP_CT_DIR_ORIGINAL)
63 statusbit = IPS_DST_NAT;
65 statusbit = IPS_SRC_NAT;
67 if (ct->status & statusbit) {
68 fl->fl4_dst = t->dst.ip;
69 if (t->dst.protonum == IPPROTO_TCP ||
70 t->dst.protonum == IPPROTO_UDP)
71 fl->fl_ip_dport = t->dst.u.tcp.port;
74 statusbit ^= IPS_NAT_MASK;
76 if (ct->status & statusbit) {
77 fl->fl4_src = t->src.ip;
78 if (t->dst.protonum == IPPROTO_TCP ||
79 t->dst.protonum == IPPROTO_UDP)
80 fl->fl_ip_sport = t->src.u.tcp.port;
86 ip_nat_fn(unsigned int hooknum,
87 struct sk_buff **pskb,
88 const struct net_device *in,
89 const struct net_device *out,
90 int (*okfn)(struct sk_buff *))
92 struct ip_conntrack *ct;
93 enum ip_conntrack_info ctinfo;
94 struct ip_nat_info *info;
95 /* maniptype == SRC for postrouting. */
96 enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
98 /* We never see fragments: conntrack defrags on pre-routing
99 and local-out, and ip_nat_out protects post-routing. */
100 IP_NF_ASSERT(!(ip_hdr(*pskb)->frag_off
101 & htons(IP_MF|IP_OFFSET)));
103 ct = ip_conntrack_get(*pskb, &ctinfo);
104 /* Can't track? It's not due to stress, or conntrack would
105 have dropped it. Hence it's the user's responsibilty to
106 packet filter it out, or implement conntrack/NAT for that
109 /* Exception: ICMP redirect to new connection (not in
110 hash table yet). We must not let this through, in
111 case we're doing NAT to the same network. */
112 if (ip_hdr(*pskb)->protocol == IPPROTO_ICMP) {
113 struct icmphdr _hdr, *hp;
115 hp = skb_header_pointer(*pskb, ip_hdrlen(*pskb),
116 sizeof(_hdr), &_hdr);
118 hp->type == ICMP_REDIRECT)
124 /* Don't try to NAT if this packet is not conntracked */
125 if (ct == &ip_conntrack_untracked)
130 case IP_CT_RELATED+IP_CT_IS_REPLY:
131 if (ip_hdr(*pskb)->protocol == IPPROTO_ICMP) {
132 if (!ip_nat_icmp_reply_translation(ct, ctinfo,
138 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
140 info = &ct->nat.info;
142 /* Seen it before? This can happen for loopback, retrans,
143 or local packets.. */
144 if (!ip_nat_initialized(ct, maniptype)) {
147 if (unlikely(is_confirmed(ct)))
148 /* NAT module was loaded late */
149 ret = alloc_null_binding_confirmed(ct, info,
151 else if (hooknum == NF_IP_LOCAL_IN)
152 /* LOCAL_IN hook doesn't have a chain! */
153 ret = alloc_null_binding(ct, info, hooknum);
155 ret = ip_nat_rule_find(pskb, hooknum,
159 if (ret != NF_ACCEPT) {
163 DEBUGP("Already setup manip %s for ct %p\n",
164 maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
170 IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
171 || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
172 info = &ct->nat.info;
176 return ip_nat_packet(ct, ctinfo, hooknum, pskb);
180 ip_nat_in(unsigned int hooknum,
181 struct sk_buff **pskb,
182 const struct net_device *in,
183 const struct net_device *out,
184 int (*okfn)(struct sk_buff *))
187 __be32 daddr = ip_hdr(*pskb)->daddr;
189 ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
190 if (ret != NF_DROP && ret != NF_STOLEN
191 && daddr != ip_hdr(*pskb)->daddr) {
192 dst_release((*pskb)->dst);
199 ip_nat_out(unsigned int hooknum,
200 struct sk_buff **pskb,
201 const struct net_device *in,
202 const struct net_device *out,
203 int (*okfn)(struct sk_buff *))
206 struct ip_conntrack *ct;
207 enum ip_conntrack_info ctinfo;
211 /* root is playing with raw sockets. */
212 if ((*pskb)->len < sizeof(struct iphdr)
213 || ip_hdrlen(*pskb) < sizeof(struct iphdr))
216 ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
218 if (ret != NF_DROP && ret != NF_STOLEN
219 && (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
220 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
222 if (ct->tuplehash[dir].tuple.src.ip !=
223 ct->tuplehash[!dir].tuple.dst.ip
224 || ct->tuplehash[dir].tuple.src.u.all !=
225 ct->tuplehash[!dir].tuple.dst.u.all
227 return ip_xfrm_me_harder(pskb) == 0 ? ret : NF_DROP;
234 ip_nat_local_fn(unsigned int hooknum,
235 struct sk_buff **pskb,
236 const struct net_device *in,
237 const struct net_device *out,
238 int (*okfn)(struct sk_buff *))
240 struct ip_conntrack *ct;
241 enum ip_conntrack_info ctinfo;
244 /* root is playing with raw sockets. */
245 if ((*pskb)->len < sizeof(struct iphdr)
246 || ip_hdrlen(*pskb) < sizeof(struct iphdr))
249 ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
250 if (ret != NF_DROP && ret != NF_STOLEN
251 && (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
252 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
254 if (ct->tuplehash[dir].tuple.dst.ip !=
255 ct->tuplehash[!dir].tuple.src.ip) {
256 if (ip_route_me_harder(pskb, RTN_UNSPEC))
260 else if (ct->tuplehash[dir].tuple.dst.u.all !=
261 ct->tuplehash[!dir].tuple.src.u.all)
262 if (ip_xfrm_me_harder(pskb))
271 ip_nat_adjust(unsigned int hooknum,
272 struct sk_buff **pskb,
273 const struct net_device *in,
274 const struct net_device *out,
275 int (*okfn)(struct sk_buff *))
277 struct ip_conntrack *ct;
278 enum ip_conntrack_info ctinfo;
280 ct = ip_conntrack_get(*pskb, &ctinfo);
281 if (ct && test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
282 DEBUGP("ip_nat_standalone: adjusting sequence number\n");
283 if (!ip_nat_seq_adjust(pskb, ct, ctinfo))
289 /* We must be after connection tracking and before packet filtering. */
291 static struct nf_hook_ops ip_nat_ops[] = {
292 /* Before packet filtering, change destination */
295 .owner = THIS_MODULE,
297 .hooknum = NF_IP_PRE_ROUTING,
298 .priority = NF_IP_PRI_NAT_DST,
300 /* After packet filtering, change source */
303 .owner = THIS_MODULE,
305 .hooknum = NF_IP_POST_ROUTING,
306 .priority = NF_IP_PRI_NAT_SRC,
308 /* After conntrack, adjust sequence number */
310 .hook = ip_nat_adjust,
311 .owner = THIS_MODULE,
313 .hooknum = NF_IP_POST_ROUTING,
314 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
316 /* Before packet filtering, change destination */
318 .hook = ip_nat_local_fn,
319 .owner = THIS_MODULE,
321 .hooknum = NF_IP_LOCAL_OUT,
322 .priority = NF_IP_PRI_NAT_DST,
324 /* After packet filtering, change source */
327 .owner = THIS_MODULE,
329 .hooknum = NF_IP_LOCAL_IN,
330 .priority = NF_IP_PRI_NAT_SRC,
332 /* After conntrack, adjust sequence number */
334 .hook = ip_nat_adjust,
335 .owner = THIS_MODULE,
337 .hooknum = NF_IP_LOCAL_IN,
338 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
342 static int __init ip_nat_standalone_init(void)
349 BUG_ON(ip_nat_decode_session != NULL);
350 ip_nat_decode_session = nat_decode_session;
352 ret = ip_nat_rule_init();
354 printk("ip_nat_init: can't setup rules.\n");
355 goto cleanup_decode_session;
357 ret = nf_register_hooks(ip_nat_ops, ARRAY_SIZE(ip_nat_ops));
359 printk("ip_nat_init: can't register hooks.\n");
360 goto cleanup_rule_init;
365 ip_nat_rule_cleanup();
366 cleanup_decode_session:
368 ip_nat_decode_session = NULL;
374 static void __exit ip_nat_standalone_fini(void)
376 nf_unregister_hooks(ip_nat_ops, ARRAY_SIZE(ip_nat_ops));
377 ip_nat_rule_cleanup();
379 ip_nat_decode_session = NULL;
384 module_init(ip_nat_standalone_init);
385 module_exit(ip_nat_standalone_fini);
387 MODULE_LICENSE("GPL");