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 static struct nf_hook_ops ip_nat_ops[] = {
303 /* Before packet filtering, change destination */
306 .owner = THIS_MODULE,
308 .hooknum = NF_IP_PRE_ROUTING,
309 .priority = NF_IP_PRI_NAT_DST,
311 /* After packet filtering, change source */
314 .owner = THIS_MODULE,
316 .hooknum = NF_IP_POST_ROUTING,
317 .priority = NF_IP_PRI_NAT_SRC,
319 /* After conntrack, adjust sequence number */
321 .hook = ip_nat_adjust,
322 .owner = THIS_MODULE,
324 .hooknum = NF_IP_POST_ROUTING,
325 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
327 /* Before packet filtering, change destination */
329 .hook = ip_nat_local_fn,
330 .owner = THIS_MODULE,
332 .hooknum = NF_IP_LOCAL_OUT,
333 .priority = NF_IP_PRI_NAT_DST,
335 /* After packet filtering, change source */
338 .owner = THIS_MODULE,
340 .hooknum = NF_IP_LOCAL_IN,
341 .priority = NF_IP_PRI_NAT_SRC,
343 /* After conntrack, adjust sequence number */
345 .hook = ip_nat_adjust,
346 .owner = THIS_MODULE,
348 .hooknum = NF_IP_LOCAL_IN,
349 .priority = NF_IP_PRI_NAT_SEQ_ADJUST,
353 static int __init ip_nat_standalone_init(void)
360 BUG_ON(ip_nat_decode_session != NULL);
361 ip_nat_decode_session = nat_decode_session;
363 ret = ip_nat_rule_init();
365 printk("ip_nat_init: can't setup rules.\n");
366 goto cleanup_decode_session;
368 ret = nf_register_hooks(ip_nat_ops, ARRAY_SIZE(ip_nat_ops));
370 printk("ip_nat_init: can't register hooks.\n");
371 goto cleanup_rule_init;
376 ip_nat_rule_cleanup();
377 cleanup_decode_session:
379 ip_nat_decode_session = NULL;
385 static void __exit ip_nat_standalone_fini(void)
387 nf_unregister_hooks(ip_nat_ops, ARRAY_SIZE(ip_nat_ops));
388 ip_nat_rule_cleanup();
390 ip_nat_decode_session = NULL;
395 module_init(ip_nat_standalone_init);
396 module_exit(ip_nat_standalone_fini);
398 MODULE_LICENSE("GPL");