[NETFILTER]: Fix section mismatch warnings
[linux-2.6.git] / net / ipv4 / netfilter / ip_nat_standalone.c
1 /* This file contains all the functions required for the standalone
2    ip_nat module.
3
4    These are not required by the compatibility layer.
5 */
6
7 /* (C) 1999-2001 Paul `Rusty' Russell
8  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
9  *
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.
13  */
14
15 /*
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
19  * */
20
21 #include <linux/config.h>
22 #include <linux/types.h>
23 #include <linux/icmp.h>
24 #include <linux/ip.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>
30 #include <net/ip.h>
31 #include <net/checksum.h>
32 #include <linux/spinlock.h>
33
34 #define ASSERT_READ_LOCK(x)
35 #define ASSERT_WRITE_LOCK(x)
36
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>
45
46 #if 0
47 #define DEBUGP printk
48 #else
49 #define DEBUGP(format, args...)
50 #endif
51
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"  \
56                                     : "*ERROR*")))
57
58 #ifdef CONFIG_XFRM
59 static void nat_decode_session(struct sk_buff *skb, struct flowi *fl)
60 {
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;
66
67         ct = ip_conntrack_get(skb, &ctinfo);
68         if (ct == NULL)
69                 return;
70         dir = CTINFO2DIR(ctinfo);
71         t = &ct->tuplehash[dir].tuple;
72
73         if (dir == IP_CT_DIR_ORIGINAL)
74                 statusbit = IPS_DST_NAT;
75         else
76                 statusbit = IPS_SRC_NAT;
77
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;
83         }
84
85         statusbit ^= IPS_NAT_MASK;
86
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;
92         }
93 }
94 #endif
95                 
96 static unsigned int
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 *))
102 {
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);
108
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)));
113
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)))
117                         return NF_DROP;
118
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
123            protocol. 8) --RR */
124         if (!ct) {
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;
130
131                         hp = skb_header_pointer(*pskb,
132                                                 (*pskb)->nh.iph->ihl*4,
133                                                 sizeof(_hdr), &_hdr);
134                         if (hp != NULL &&
135                             hp->type == ICMP_REDIRECT)
136                                 return NF_DROP;
137                 }
138                 return NF_ACCEPT;
139         }
140
141         /* Don't try to NAT if this packet is not conntracked */
142         if (ct == &ip_conntrack_untracked)
143                 return NF_ACCEPT;
144
145         switch (ctinfo) {
146         case IP_CT_RELATED:
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,
150                                                            CTINFO2DIR(ctinfo)))
151                                 return NF_DROP;
152                         else
153                                 return NF_ACCEPT;
154                 }
155                 /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
156         case IP_CT_NEW:
157                 info = &ct->nat.info;
158
159                 /* Seen it before?  This can happen for loopback, retrans,
160                    or local packets.. */
161                 if (!ip_nat_initialized(ct, maniptype)) {
162                         unsigned int ret;
163
164                         if (unlikely(is_confirmed(ct)))
165                                 /* NAT module was loaded late */
166                                 ret = alloc_null_binding_confirmed(ct, info,
167                                                                    hooknum);
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);
171                         else
172                                 ret = ip_nat_rule_find(pskb, hooknum,
173                                                        in, out, ct,
174                                                        info);
175
176                         if (ret != NF_ACCEPT) {
177                                 return ret;
178                         }
179                 } else
180                         DEBUGP("Already setup manip %s for ct %p\n",
181                                maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
182                                ct);
183                 break;
184
185         default:
186                 /* ESTABLISHED */
187                 IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
188                              || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
189                 info = &ct->nat.info;
190         }
191
192         IP_NF_ASSERT(info);
193         return ip_nat_packet(ct, ctinfo, hooknum, pskb);
194 }
195
196 static unsigned int
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 *))
202 {
203         unsigned int ret;
204         u_int32_t daddr = (*pskb)->nh.iph->daddr;
205
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);
210                 (*pskb)->dst = NULL;
211         }
212         return ret;
213 }
214
215 static unsigned int
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 *))
221 {
222         struct ip_conntrack *ct;
223         enum ip_conntrack_info ctinfo;
224         unsigned int ret;
225
226         /* root is playing with raw sockets. */
227         if ((*pskb)->len < sizeof(struct iphdr)
228             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
229                 return NF_ACCEPT;
230
231         ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
232 #ifdef CONFIG_XFRM
233         if (ret != NF_DROP && ret != NF_STOLEN
234             && (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
235                 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
236
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
241                     )
242                         return ip_xfrm_me_harder(pskb) == 0 ? ret : NF_DROP;
243         }
244 #endif
245         return ret;
246 }
247
248 static unsigned int
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 *))
254 {
255         struct ip_conntrack *ct;
256         enum ip_conntrack_info ctinfo;
257         unsigned int ret;
258
259         /* root is playing with raw sockets. */
260         if ((*pskb)->len < sizeof(struct iphdr)
261             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
262                 return NF_ACCEPT;
263
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);
268
269                 if (ct->tuplehash[dir].tuple.dst.ip !=
270                     ct->tuplehash[!dir].tuple.src.ip
271 #ifdef CONFIG_XFRM
272                     || ct->tuplehash[dir].tuple.dst.u.all !=
273                        ct->tuplehash[!dir].tuple.src.u.all
274 #endif
275                     )
276                         return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
277         }
278         return ret;
279 }
280
281 static unsigned int
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 *))
287 {
288         struct ip_conntrack *ct;
289         enum ip_conntrack_info ctinfo;
290
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))
295                         return NF_DROP;
296         }
297         return NF_ACCEPT;
298 }
299
300 /* We must be after connection tracking and before packet filtering. */
301
302 static struct nf_hook_ops ip_nat_ops[] = {
303         /* Before packet filtering, change destination */
304         {
305                 .hook           = ip_nat_in,
306                 .owner          = THIS_MODULE,
307                 .pf             = PF_INET,
308                 .hooknum        = NF_IP_PRE_ROUTING,
309                 .priority       = NF_IP_PRI_NAT_DST,
310         },
311         /* After packet filtering, change source */
312         {
313                 .hook           = ip_nat_out,
314                 .owner          = THIS_MODULE,
315                 .pf             = PF_INET,
316                 .hooknum        = NF_IP_POST_ROUTING,
317                 .priority       = NF_IP_PRI_NAT_SRC,
318         },
319         /* After conntrack, adjust sequence number */
320         {
321                 .hook           = ip_nat_adjust,
322                 .owner          = THIS_MODULE,
323                 .pf             = PF_INET,
324                 .hooknum        = NF_IP_POST_ROUTING,
325                 .priority       = NF_IP_PRI_NAT_SEQ_ADJUST,
326         },
327         /* Before packet filtering, change destination */
328         {
329                 .hook           = ip_nat_local_fn,
330                 .owner          = THIS_MODULE,
331                 .pf             = PF_INET,
332                 .hooknum        = NF_IP_LOCAL_OUT,
333                 .priority       = NF_IP_PRI_NAT_DST,
334         },
335         /* After packet filtering, change source */
336         {
337                 .hook           = ip_nat_fn,
338                 .owner          = THIS_MODULE,
339                 .pf             = PF_INET,
340                 .hooknum        = NF_IP_LOCAL_IN,
341                 .priority       = NF_IP_PRI_NAT_SRC,
342         },
343         /* After conntrack, adjust sequence number */
344         {
345                 .hook           = ip_nat_adjust,
346                 .owner          = THIS_MODULE,
347                 .pf             = PF_INET,
348                 .hooknum        = NF_IP_LOCAL_IN,
349                 .priority       = NF_IP_PRI_NAT_SEQ_ADJUST,
350         },
351 };
352
353 static int __init ip_nat_standalone_init(void)
354 {
355         int ret = 0;
356
357         need_conntrack();
358
359 #ifdef CONFIG_XFRM
360         BUG_ON(ip_nat_decode_session != NULL);
361         ip_nat_decode_session = nat_decode_session;
362 #endif
363         ret = ip_nat_rule_init();
364         if (ret < 0) {
365                 printk("ip_nat_init: can't setup rules.\n");
366                 goto cleanup_decode_session;
367         }
368         ret = nf_register_hooks(ip_nat_ops, ARRAY_SIZE(ip_nat_ops));
369         if (ret < 0) {
370                 printk("ip_nat_init: can't register hooks.\n");
371                 goto cleanup_rule_init;
372         }
373         return ret;
374
375  cleanup_rule_init:
376         ip_nat_rule_cleanup();
377  cleanup_decode_session:
378 #ifdef CONFIG_XFRM
379         ip_nat_decode_session = NULL;
380         synchronize_net();
381 #endif
382         return ret;
383 }
384
385 static void __exit ip_nat_standalone_fini(void)
386 {
387         nf_unregister_hooks(ip_nat_ops, ARRAY_SIZE(ip_nat_ops));
388         ip_nat_rule_cleanup();
389 #ifdef CONFIG_XFRM
390         ip_nat_decode_session = NULL;
391         synchronize_net();
392 #endif
393 }
394
395 module_init(ip_nat_standalone_init);
396 module_exit(ip_nat_standalone_fini);
397
398 MODULE_LICENSE("GPL");