[IP]: Introduce ip_hdrlen()
[linux-3.10.git] / net / ipv4 / netfilter / nf_nat_core.c
1 /* NAT for netfilter; shared with compatibility layer. */
2
3 /* (C) 1999-2001 Paul `Rusty' Russell
4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include <linux/timer.h>
14 #include <linux/skbuff.h>
15 #include <linux/vmalloc.h>
16 #include <net/checksum.h>
17 #include <net/icmp.h>
18 #include <net/ip.h>
19 #include <net/tcp.h>  /* For tcp_prot in getorigdst */
20 #include <linux/icmp.h>
21 #include <linux/udp.h>
22 #include <linux/jhash.h>
23
24 #include <linux/netfilter_ipv4.h>
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_core.h>
27 #include <net/netfilter/nf_nat.h>
28 #include <net/netfilter/nf_nat_protocol.h>
29 #include <net/netfilter/nf_nat_core.h>
30 #include <net/netfilter/nf_nat_helper.h>
31 #include <net/netfilter/nf_conntrack_helper.h>
32 #include <net/netfilter/nf_conntrack_l3proto.h>
33 #include <net/netfilter/nf_conntrack_l4proto.h>
34
35 #if 0
36 #define DEBUGP printk
37 #else
38 #define DEBUGP(format, args...)
39 #endif
40
41 static DEFINE_RWLOCK(nf_nat_lock);
42
43 static struct nf_conntrack_l3proto *l3proto = NULL;
44
45 /* Calculated at init based on memory size */
46 static unsigned int nf_nat_htable_size;
47
48 static struct list_head *bysource;
49
50 #define MAX_IP_NAT_PROTO 256
51 static struct nf_nat_protocol *nf_nat_protos[MAX_IP_NAT_PROTO];
52
53 static inline struct nf_nat_protocol *
54 __nf_nat_proto_find(u_int8_t protonum)
55 {
56         return rcu_dereference(nf_nat_protos[protonum]);
57 }
58
59 struct nf_nat_protocol *
60 nf_nat_proto_find_get(u_int8_t protonum)
61 {
62         struct nf_nat_protocol *p;
63
64         rcu_read_lock();
65         p = __nf_nat_proto_find(protonum);
66         if (!try_module_get(p->me))
67                 p = &nf_nat_unknown_protocol;
68         rcu_read_unlock();
69
70         return p;
71 }
72 EXPORT_SYMBOL_GPL(nf_nat_proto_find_get);
73
74 void
75 nf_nat_proto_put(struct nf_nat_protocol *p)
76 {
77         module_put(p->me);
78 }
79 EXPORT_SYMBOL_GPL(nf_nat_proto_put);
80
81 /* We keep an extra hash for each conntrack, for fast searching. */
82 static inline unsigned int
83 hash_by_src(const struct nf_conntrack_tuple *tuple)
84 {
85         /* Original src, to ensure we map it consistently if poss. */
86         return jhash_3words((__force u32)tuple->src.u3.ip, tuple->src.u.all,
87                             tuple->dst.protonum, 0) % nf_nat_htable_size;
88 }
89
90 /* Noone using conntrack by the time this called. */
91 static void nf_nat_cleanup_conntrack(struct nf_conn *conn)
92 {
93         struct nf_conn_nat *nat;
94         if (!(conn->status & IPS_NAT_DONE_MASK))
95                 return;
96
97         nat = nfct_nat(conn);
98         write_lock_bh(&nf_nat_lock);
99         list_del(&nat->info.bysource);
100         write_unlock_bh(&nf_nat_lock);
101 }
102
103 /* Is this tuple already taken? (not by us) */
104 int
105 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
106                   const struct nf_conn *ignored_conntrack)
107 {
108         /* Conntrack tracking doesn't keep track of outgoing tuples; only
109            incoming ones.  NAT means they don't have a fixed mapping,
110            so we invert the tuple and look for the incoming reply.
111
112            We could keep a separate hash if this proves too slow. */
113         struct nf_conntrack_tuple reply;
114
115         nf_ct_invert_tuplepr(&reply, tuple);
116         return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
117 }
118 EXPORT_SYMBOL(nf_nat_used_tuple);
119
120 /* If we source map this tuple so reply looks like reply_tuple, will
121  * that meet the constraints of range. */
122 static int
123 in_range(const struct nf_conntrack_tuple *tuple,
124          const struct nf_nat_range *range)
125 {
126         struct nf_nat_protocol *proto;
127         int ret = 0;
128
129         /* If we are supposed to map IPs, then we must be in the
130            range specified, otherwise let this drag us onto a new src IP. */
131         if (range->flags & IP_NAT_RANGE_MAP_IPS) {
132                 if (ntohl(tuple->src.u3.ip) < ntohl(range->min_ip) ||
133                     ntohl(tuple->src.u3.ip) > ntohl(range->max_ip))
134                         return 0;
135         }
136
137         rcu_read_lock();
138         proto = __nf_nat_proto_find(tuple->dst.protonum);
139         if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
140             proto->in_range(tuple, IP_NAT_MANIP_SRC,
141                             &range->min, &range->max))
142                 ret = 1;
143         rcu_read_unlock();
144
145         return ret;
146 }
147
148 static inline int
149 same_src(const struct nf_conn *ct,
150          const struct nf_conntrack_tuple *tuple)
151 {
152         const struct nf_conntrack_tuple *t;
153
154         t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
155         return (t->dst.protonum == tuple->dst.protonum &&
156                 t->src.u3.ip == tuple->src.u3.ip &&
157                 t->src.u.all == tuple->src.u.all);
158 }
159
160 /* Only called for SRC manip */
161 static int
162 find_appropriate_src(const struct nf_conntrack_tuple *tuple,
163                      struct nf_conntrack_tuple *result,
164                      const struct nf_nat_range *range)
165 {
166         unsigned int h = hash_by_src(tuple);
167         struct nf_conn_nat *nat;
168         struct nf_conn *ct;
169
170         read_lock_bh(&nf_nat_lock);
171         list_for_each_entry(nat, &bysource[h], info.bysource) {
172                 ct = (struct nf_conn *)((char *)nat - offsetof(struct nf_conn, data));
173                 if (same_src(ct, tuple)) {
174                         /* Copy source part from reply tuple. */
175                         nf_ct_invert_tuplepr(result,
176                                        &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
177                         result->dst = tuple->dst;
178
179                         if (in_range(result, range)) {
180                                 read_unlock_bh(&nf_nat_lock);
181                                 return 1;
182                         }
183                 }
184         }
185         read_unlock_bh(&nf_nat_lock);
186         return 0;
187 }
188
189 /* For [FUTURE] fragmentation handling, we want the least-used
190    src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
191    if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
192    1-65535, we don't do pro-rata allocation based on ports; we choose
193    the ip with the lowest src-ip/dst-ip/proto usage.
194 */
195 static void
196 find_best_ips_proto(struct nf_conntrack_tuple *tuple,
197                     const struct nf_nat_range *range,
198                     const struct nf_conn *ct,
199                     enum nf_nat_manip_type maniptype)
200 {
201         __be32 *var_ipp;
202         /* Host order */
203         u_int32_t minip, maxip, j;
204
205         /* No IP mapping?  Do nothing. */
206         if (!(range->flags & IP_NAT_RANGE_MAP_IPS))
207                 return;
208
209         if (maniptype == IP_NAT_MANIP_SRC)
210                 var_ipp = &tuple->src.u3.ip;
211         else
212                 var_ipp = &tuple->dst.u3.ip;
213
214         /* Fast path: only one choice. */
215         if (range->min_ip == range->max_ip) {
216                 *var_ipp = range->min_ip;
217                 return;
218         }
219
220         /* Hashing source and destination IPs gives a fairly even
221          * spread in practice (if there are a small number of IPs
222          * involved, there usually aren't that many connections
223          * anyway).  The consistency means that servers see the same
224          * client coming from the same IP (some Internet Banking sites
225          * like this), even across reboots. */
226         minip = ntohl(range->min_ip);
227         maxip = ntohl(range->max_ip);
228         j = jhash_2words((__force u32)tuple->src.u3.ip,
229                          (__force u32)tuple->dst.u3.ip, 0);
230         *var_ipp = htonl(minip + j % (maxip - minip + 1));
231 }
232
233 /* Manipulate the tuple into the range given.  For NF_IP_POST_ROUTING,
234  * we change the source to map into the range.  For NF_IP_PRE_ROUTING
235  * and NF_IP_LOCAL_OUT, we change the destination to map into the
236  * range.  It might not be possible to get a unique tuple, but we try.
237  * At worst (or if we race), we will end up with a final duplicate in
238  * __ip_conntrack_confirm and drop the packet. */
239 static void
240 get_unique_tuple(struct nf_conntrack_tuple *tuple,
241                  const struct nf_conntrack_tuple *orig_tuple,
242                  const struct nf_nat_range *range,
243                  struct nf_conn *ct,
244                  enum nf_nat_manip_type maniptype)
245 {
246         struct nf_nat_protocol *proto;
247
248         /* 1) If this srcip/proto/src-proto-part is currently mapped,
249            and that same mapping gives a unique tuple within the given
250            range, use that.
251
252            This is only required for source (ie. NAT/masq) mappings.
253            So far, we don't do local source mappings, so multiple
254            manips not an issue.  */
255         if (maniptype == IP_NAT_MANIP_SRC) {
256                 if (find_appropriate_src(orig_tuple, tuple, range)) {
257                         DEBUGP("get_unique_tuple: Found current src map\n");
258                         if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
259                                 if (!nf_nat_used_tuple(tuple, ct))
260                                         return;
261                 }
262         }
263
264         /* 2) Select the least-used IP/proto combination in the given
265            range. */
266         *tuple = *orig_tuple;
267         find_best_ips_proto(tuple, range, ct, maniptype);
268
269         /* 3) The per-protocol part of the manip is made to map into
270            the range to make a unique tuple. */
271
272         rcu_read_lock();
273         proto = __nf_nat_proto_find(orig_tuple->dst.protonum);
274
275         /* Change protocol info to have some randomization */
276         if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) {
277                 proto->unique_tuple(tuple, range, maniptype, ct);
278                 goto out;
279         }
280
281         /* Only bother mapping if it's not already in range and unique */
282         if ((!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
283              proto->in_range(tuple, maniptype, &range->min, &range->max)) &&
284             !nf_nat_used_tuple(tuple, ct))
285                 goto out;
286
287         /* Last change: get protocol to try to obtain unique tuple. */
288         proto->unique_tuple(tuple, range, maniptype, ct);
289 out:
290         rcu_read_unlock();
291 }
292
293 unsigned int
294 nf_nat_setup_info(struct nf_conn *ct,
295                   const struct nf_nat_range *range,
296                   unsigned int hooknum)
297 {
298         struct nf_conntrack_tuple curr_tuple, new_tuple;
299         struct nf_conn_nat *nat = nfct_nat(ct);
300         struct nf_nat_info *info = &nat->info;
301         int have_to_hash = !(ct->status & IPS_NAT_DONE_MASK);
302         enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum);
303
304         NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
305                      hooknum == NF_IP_POST_ROUTING ||
306                      hooknum == NF_IP_LOCAL_IN ||
307                      hooknum == NF_IP_LOCAL_OUT);
308         BUG_ON(nf_nat_initialized(ct, maniptype));
309
310         /* What we've got will look like inverse of reply. Normally
311            this is what is in the conntrack, except for prior
312            manipulations (future optimization: if num_manips == 0,
313            orig_tp =
314            conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple) */
315         nf_ct_invert_tuplepr(&curr_tuple,
316                              &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
317
318         get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
319
320         if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
321                 struct nf_conntrack_tuple reply;
322
323                 /* Alter conntrack table so will recognize replies. */
324                 nf_ct_invert_tuplepr(&reply, &new_tuple);
325                 nf_conntrack_alter_reply(ct, &reply);
326
327                 /* Non-atomic: we own this at the moment. */
328                 if (maniptype == IP_NAT_MANIP_SRC)
329                         ct->status |= IPS_SRC_NAT;
330                 else
331                         ct->status |= IPS_DST_NAT;
332         }
333
334         /* Place in source hash if this is the first time. */
335         if (have_to_hash) {
336                 unsigned int srchash;
337
338                 srchash = hash_by_src(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
339                 write_lock_bh(&nf_nat_lock);
340                 list_add(&info->bysource, &bysource[srchash]);
341                 write_unlock_bh(&nf_nat_lock);
342         }
343
344         /* It's done. */
345         if (maniptype == IP_NAT_MANIP_DST)
346                 set_bit(IPS_DST_NAT_DONE_BIT, &ct->status);
347         else
348                 set_bit(IPS_SRC_NAT_DONE_BIT, &ct->status);
349
350         return NF_ACCEPT;
351 }
352 EXPORT_SYMBOL(nf_nat_setup_info);
353
354 /* Returns true if succeeded. */
355 static int
356 manip_pkt(u_int16_t proto,
357           struct sk_buff **pskb,
358           unsigned int iphdroff,
359           const struct nf_conntrack_tuple *target,
360           enum nf_nat_manip_type maniptype)
361 {
362         struct iphdr *iph;
363         struct nf_nat_protocol *p;
364
365         if (!skb_make_writable(pskb, iphdroff + sizeof(*iph)))
366                 return 0;
367
368         iph = (void *)(*pskb)->data + iphdroff;
369
370         /* Manipulate protcol part. */
371
372         /* rcu_read_lock()ed by nf_hook_slow */
373         p = __nf_nat_proto_find(proto);
374         if (!p->manip_pkt(pskb, iphdroff, target, maniptype))
375                 return 0;
376
377         iph = (void *)(*pskb)->data + iphdroff;
378
379         if (maniptype == IP_NAT_MANIP_SRC) {
380                 nf_csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
381                 iph->saddr = target->src.u3.ip;
382         } else {
383                 nf_csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
384                 iph->daddr = target->dst.u3.ip;
385         }
386         return 1;
387 }
388
389 /* Do packet manipulations according to nf_nat_setup_info. */
390 unsigned int nf_nat_packet(struct nf_conn *ct,
391                            enum ip_conntrack_info ctinfo,
392                            unsigned int hooknum,
393                            struct sk_buff **pskb)
394 {
395         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
396         unsigned long statusbit;
397         enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
398
399         if (mtype == IP_NAT_MANIP_SRC)
400                 statusbit = IPS_SRC_NAT;
401         else
402                 statusbit = IPS_DST_NAT;
403
404         /* Invert if this is reply dir. */
405         if (dir == IP_CT_DIR_REPLY)
406                 statusbit ^= IPS_NAT_MASK;
407
408         /* Non-atomic: these bits don't change. */
409         if (ct->status & statusbit) {
410                 struct nf_conntrack_tuple target;
411
412                 /* We are aiming to look like inverse of other direction. */
413                 nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
414
415                 if (!manip_pkt(target.dst.protonum, pskb, 0, &target, mtype))
416                         return NF_DROP;
417         }
418         return NF_ACCEPT;
419 }
420 EXPORT_SYMBOL_GPL(nf_nat_packet);
421
422 /* Dir is direction ICMP is coming from (opposite to packet it contains) */
423 int nf_nat_icmp_reply_translation(struct nf_conn *ct,
424                                   enum ip_conntrack_info ctinfo,
425                                   unsigned int hooknum,
426                                   struct sk_buff **pskb)
427 {
428         struct {
429                 struct icmphdr icmp;
430                 struct iphdr ip;
431         } *inside;
432         struct nf_conntrack_l4proto *l4proto;
433         struct nf_conntrack_tuple inner, target;
434         int hdrlen = ip_hdrlen(*pskb);
435         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
436         unsigned long statusbit;
437         enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
438
439         if (!skb_make_writable(pskb, hdrlen + sizeof(*inside)))
440                 return 0;
441
442         inside = (void *)(*pskb)->data + ip_hdrlen(*pskb);
443
444         /* We're actually going to mangle it beyond trivial checksum
445            adjustment, so make sure the current checksum is correct. */
446         if (nf_ip_checksum(*pskb, hooknum, hdrlen, 0))
447                 return 0;
448
449         /* Must be RELATED */
450         NF_CT_ASSERT((*pskb)->nfctinfo == IP_CT_RELATED ||
451                      (*pskb)->nfctinfo == IP_CT_RELATED+IP_CT_IS_REPLY);
452
453         /* Redirects on non-null nats must be dropped, else they'll
454            start talking to each other without our translation, and be
455            confused... --RR */
456         if (inside->icmp.type == ICMP_REDIRECT) {
457                 /* If NAT isn't finished, assume it and drop. */
458                 if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
459                         return 0;
460
461                 if (ct->status & IPS_NAT_MASK)
462                         return 0;
463         }
464
465         DEBUGP("icmp_reply_translation: translating error %p manp %u dir %s\n",
466                *pskb, manip, dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY");
467
468         /* rcu_read_lock()ed by nf_hook_slow */
469         l4proto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
470
471         if (!nf_ct_get_tuple(*pskb,
472                              ip_hdrlen(*pskb) + sizeof(struct icmphdr),
473                              (ip_hdrlen(*pskb) +
474                               sizeof(struct icmphdr) + inside->ip.ihl * 4),
475                              (u_int16_t)AF_INET,
476                              inside->ip.protocol,
477                              &inner, l3proto, l4proto))
478                 return 0;
479
480         /* Change inner back to look like incoming packet.  We do the
481            opposite manip on this hook to normal, because it might not
482            pass all hooks (locally-generated ICMP).  Consider incoming
483            packet: PREROUTING (DST manip), routing produces ICMP, goes
484            through POSTROUTING (which must correct the DST manip). */
485         if (!manip_pkt(inside->ip.protocol, pskb,
486                        ip_hdrlen(*pskb) + sizeof(inside->icmp),
487                        &ct->tuplehash[!dir].tuple,
488                        !manip))
489                 return 0;
490
491         if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) {
492                 /* Reloading "inside" here since manip_pkt inner. */
493                 inside = (void *)(*pskb)->data + ip_hdrlen(*pskb);
494                 inside->icmp.checksum = 0;
495                 inside->icmp.checksum =
496                         csum_fold(skb_checksum(*pskb, hdrlen,
497                                                (*pskb)->len - hdrlen, 0));
498         }
499
500         /* Change outer to look the reply to an incoming packet
501          * (proto 0 means don't invert per-proto part). */
502         if (manip == IP_NAT_MANIP_SRC)
503                 statusbit = IPS_SRC_NAT;
504         else
505                 statusbit = IPS_DST_NAT;
506
507         /* Invert if this is reply dir. */
508         if (dir == IP_CT_DIR_REPLY)
509                 statusbit ^= IPS_NAT_MASK;
510
511         if (ct->status & statusbit) {
512                 nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
513                 if (!manip_pkt(0, pskb, 0, &target, manip))
514                         return 0;
515         }
516
517         return 1;
518 }
519 EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);
520
521 /* Protocol registration. */
522 int nf_nat_protocol_register(struct nf_nat_protocol *proto)
523 {
524         int ret = 0;
525
526         write_lock_bh(&nf_nat_lock);
527         if (nf_nat_protos[proto->protonum] != &nf_nat_unknown_protocol) {
528                 ret = -EBUSY;
529                 goto out;
530         }
531         rcu_assign_pointer(nf_nat_protos[proto->protonum], proto);
532  out:
533         write_unlock_bh(&nf_nat_lock);
534         return ret;
535 }
536 EXPORT_SYMBOL(nf_nat_protocol_register);
537
538 /* Noone stores the protocol anywhere; simply delete it. */
539 void nf_nat_protocol_unregister(struct nf_nat_protocol *proto)
540 {
541         write_lock_bh(&nf_nat_lock);
542         rcu_assign_pointer(nf_nat_protos[proto->protonum],
543                            &nf_nat_unknown_protocol);
544         write_unlock_bh(&nf_nat_lock);
545         synchronize_rcu();
546 }
547 EXPORT_SYMBOL(nf_nat_protocol_unregister);
548
549 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
550 int
551 nf_nat_port_range_to_nfattr(struct sk_buff *skb,
552                             const struct nf_nat_range *range)
553 {
554         NFA_PUT(skb, CTA_PROTONAT_PORT_MIN, sizeof(__be16),
555                 &range->min.tcp.port);
556         NFA_PUT(skb, CTA_PROTONAT_PORT_MAX, sizeof(__be16),
557                 &range->max.tcp.port);
558
559         return 0;
560
561 nfattr_failure:
562         return -1;
563 }
564 EXPORT_SYMBOL_GPL(nf_nat_port_nfattr_to_range);
565
566 int
567 nf_nat_port_nfattr_to_range(struct nfattr *tb[], struct nf_nat_range *range)
568 {
569         int ret = 0;
570
571         /* we have to return whether we actually parsed something or not */
572
573         if (tb[CTA_PROTONAT_PORT_MIN-1]) {
574                 ret = 1;
575                 range->min.tcp.port =
576                         *(__be16 *)NFA_DATA(tb[CTA_PROTONAT_PORT_MIN-1]);
577         }
578
579         if (!tb[CTA_PROTONAT_PORT_MAX-1]) {
580                 if (ret)
581                         range->max.tcp.port = range->min.tcp.port;
582         } else {
583                 ret = 1;
584                 range->max.tcp.port =
585                         *(__be16 *)NFA_DATA(tb[CTA_PROTONAT_PORT_MAX-1]);
586         }
587
588         return ret;
589 }
590 EXPORT_SYMBOL_GPL(nf_nat_port_range_to_nfattr);
591 #endif
592
593 static int __init nf_nat_init(void)
594 {
595         size_t i;
596
597         /* Leave them the same for the moment. */
598         nf_nat_htable_size = nf_conntrack_htable_size;
599
600         /* One vmalloc for both hash tables */
601         bysource = vmalloc(sizeof(struct list_head) * nf_nat_htable_size);
602         if (!bysource)
603                 return -ENOMEM;
604
605         /* Sew in builtin protocols. */
606         write_lock_bh(&nf_nat_lock);
607         for (i = 0; i < MAX_IP_NAT_PROTO; i++)
608                 rcu_assign_pointer(nf_nat_protos[i], &nf_nat_unknown_protocol);
609         rcu_assign_pointer(nf_nat_protos[IPPROTO_TCP], &nf_nat_protocol_tcp);
610         rcu_assign_pointer(nf_nat_protos[IPPROTO_UDP], &nf_nat_protocol_udp);
611         rcu_assign_pointer(nf_nat_protos[IPPROTO_ICMP], &nf_nat_protocol_icmp);
612         write_unlock_bh(&nf_nat_lock);
613
614         for (i = 0; i < nf_nat_htable_size; i++) {
615                 INIT_LIST_HEAD(&bysource[i]);
616         }
617
618         /* FIXME: Man, this is a hack.  <SIGH> */
619         NF_CT_ASSERT(rcu_dereference(nf_conntrack_destroyed) == NULL);
620         rcu_assign_pointer(nf_conntrack_destroyed, nf_nat_cleanup_conntrack);
621
622         /* Initialize fake conntrack so that NAT will skip it */
623         nf_conntrack_untracked.status |= IPS_NAT_DONE_MASK;
624
625         l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET);
626         return 0;
627 }
628
629 /* Clear NAT section of all conntracks, in case we're loaded again. */
630 static int clean_nat(struct nf_conn *i, void *data)
631 {
632         struct nf_conn_nat *nat = nfct_nat(i);
633
634         if (!nat)
635                 return 0;
636         memset(nat, 0, sizeof(nat));
637         i->status &= ~(IPS_NAT_MASK | IPS_NAT_DONE_MASK | IPS_SEQ_ADJUST);
638         return 0;
639 }
640
641 static void __exit nf_nat_cleanup(void)
642 {
643         nf_ct_iterate_cleanup(&clean_nat, NULL);
644         rcu_assign_pointer(nf_conntrack_destroyed, NULL);
645         synchronize_rcu();
646         vfree(bysource);
647         nf_ct_l3proto_put(l3proto);
648 }
649
650 MODULE_LICENSE("GPL");
651
652 module_init(nf_nat_init);
653 module_exit(nf_nat_cleanup);