7cc179cfc7c11b3277c3fa86aaee6bf492fd19a1
[linux-2.6.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 <net/checksum.h>
16 #include <net/icmp.h>
17 #include <net/ip.h>
18 #include <net/tcp.h>  /* For tcp_prot in getorigdst */
19 #include <linux/icmp.h>
20 #include <linux/udp.h>
21 #include <linux/jhash.h>
22
23 #include <linux/netfilter_ipv4.h>
24 #include <net/netfilter/nf_conntrack.h>
25 #include <net/netfilter/nf_conntrack_core.h>
26 #include <net/netfilter/nf_nat.h>
27 #include <net/netfilter/nf_nat_protocol.h>
28 #include <net/netfilter/nf_nat_core.h>
29 #include <net/netfilter/nf_nat_helper.h>
30 #include <net/netfilter/nf_conntrack_helper.h>
31 #include <net/netfilter/nf_conntrack_l3proto.h>
32 #include <net/netfilter/nf_conntrack_l4proto.h>
33
34 static DEFINE_RWLOCK(nf_nat_lock);
35
36 static struct nf_conntrack_l3proto *l3proto __read_mostly;
37
38 /* Calculated at init based on memory size */
39 static unsigned int nf_nat_htable_size __read_mostly;
40 static int nf_nat_vmalloced;
41
42 static struct hlist_head *bysource __read_mostly;
43
44 #define MAX_IP_NAT_PROTO 256
45 static const struct nf_nat_protocol *nf_nat_protos[MAX_IP_NAT_PROTO]
46                                                 __read_mostly;
47
48 static inline const struct nf_nat_protocol *
49 __nf_nat_proto_find(u_int8_t protonum)
50 {
51         return rcu_dereference(nf_nat_protos[protonum]);
52 }
53
54 const struct nf_nat_protocol *
55 nf_nat_proto_find_get(u_int8_t protonum)
56 {
57         const struct nf_nat_protocol *p;
58
59         rcu_read_lock();
60         p = __nf_nat_proto_find(protonum);
61         if (!try_module_get(p->me))
62                 p = &nf_nat_unknown_protocol;
63         rcu_read_unlock();
64
65         return p;
66 }
67 EXPORT_SYMBOL_GPL(nf_nat_proto_find_get);
68
69 void
70 nf_nat_proto_put(const struct nf_nat_protocol *p)
71 {
72         module_put(p->me);
73 }
74 EXPORT_SYMBOL_GPL(nf_nat_proto_put);
75
76 /* We keep an extra hash for each conntrack, for fast searching. */
77 static inline unsigned int
78 hash_by_src(const struct nf_conntrack_tuple *tuple)
79 {
80         /* Original src, to ensure we map it consistently if poss. */
81         return jhash_3words((__force u32)tuple->src.u3.ip,
82                             (__force u32)tuple->src.u.all,
83                             tuple->dst.protonum, 0) % nf_nat_htable_size;
84 }
85
86 /* Is this tuple already taken? (not by us) */
87 int
88 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
89                   const struct nf_conn *ignored_conntrack)
90 {
91         /* Conntrack tracking doesn't keep track of outgoing tuples; only
92            incoming ones.  NAT means they don't have a fixed mapping,
93            so we invert the tuple and look for the incoming reply.
94
95            We could keep a separate hash if this proves too slow. */
96         struct nf_conntrack_tuple reply;
97
98         nf_ct_invert_tuplepr(&reply, tuple);
99         return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
100 }
101 EXPORT_SYMBOL(nf_nat_used_tuple);
102
103 /* If we source map this tuple so reply looks like reply_tuple, will
104  * that meet the constraints of range. */
105 static int
106 in_range(const struct nf_conntrack_tuple *tuple,
107          const struct nf_nat_range *range)
108 {
109         const struct nf_nat_protocol *proto;
110         int ret = 0;
111
112         /* If we are supposed to map IPs, then we must be in the
113            range specified, otherwise let this drag us onto a new src IP. */
114         if (range->flags & IP_NAT_RANGE_MAP_IPS) {
115                 if (ntohl(tuple->src.u3.ip) < ntohl(range->min_ip) ||
116                     ntohl(tuple->src.u3.ip) > ntohl(range->max_ip))
117                         return 0;
118         }
119
120         rcu_read_lock();
121         proto = __nf_nat_proto_find(tuple->dst.protonum);
122         if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
123             proto->in_range(tuple, IP_NAT_MANIP_SRC,
124                             &range->min, &range->max))
125                 ret = 1;
126         rcu_read_unlock();
127
128         return ret;
129 }
130
131 static inline int
132 same_src(const struct nf_conn *ct,
133          const struct nf_conntrack_tuple *tuple)
134 {
135         const struct nf_conntrack_tuple *t;
136
137         t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
138         return (t->dst.protonum == tuple->dst.protonum &&
139                 t->src.u3.ip == tuple->src.u3.ip &&
140                 t->src.u.all == tuple->src.u.all);
141 }
142
143 /* Only called for SRC manip */
144 static int
145 find_appropriate_src(const struct nf_conntrack_tuple *tuple,
146                      struct nf_conntrack_tuple *result,
147                      const struct nf_nat_range *range)
148 {
149         unsigned int h = hash_by_src(tuple);
150         struct nf_conn_nat *nat;
151         struct nf_conn *ct;
152         struct hlist_node *n;
153
154         read_lock_bh(&nf_nat_lock);
155         hlist_for_each_entry(nat, n, &bysource[h], bysource) {
156                 ct = nat->ct;
157                 if (same_src(ct, tuple)) {
158                         /* Copy source part from reply tuple. */
159                         nf_ct_invert_tuplepr(result,
160                                        &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
161                         result->dst = tuple->dst;
162
163                         if (in_range(result, range)) {
164                                 read_unlock_bh(&nf_nat_lock);
165                                 return 1;
166                         }
167                 }
168         }
169         read_unlock_bh(&nf_nat_lock);
170         return 0;
171 }
172
173 /* For [FUTURE] fragmentation handling, we want the least-used
174    src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
175    if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
176    1-65535, we don't do pro-rata allocation based on ports; we choose
177    the ip with the lowest src-ip/dst-ip/proto usage.
178 */
179 static void
180 find_best_ips_proto(struct nf_conntrack_tuple *tuple,
181                     const struct nf_nat_range *range,
182                     const struct nf_conn *ct,
183                     enum nf_nat_manip_type maniptype)
184 {
185         __be32 *var_ipp;
186         /* Host order */
187         u_int32_t minip, maxip, j;
188
189         /* No IP mapping?  Do nothing. */
190         if (!(range->flags & IP_NAT_RANGE_MAP_IPS))
191                 return;
192
193         if (maniptype == IP_NAT_MANIP_SRC)
194                 var_ipp = &tuple->src.u3.ip;
195         else
196                 var_ipp = &tuple->dst.u3.ip;
197
198         /* Fast path: only one choice. */
199         if (range->min_ip == range->max_ip) {
200                 *var_ipp = range->min_ip;
201                 return;
202         }
203
204         /* Hashing source and destination IPs gives a fairly even
205          * spread in practice (if there are a small number of IPs
206          * involved, there usually aren't that many connections
207          * anyway).  The consistency means that servers see the same
208          * client coming from the same IP (some Internet Banking sites
209          * like this), even across reboots. */
210         minip = ntohl(range->min_ip);
211         maxip = ntohl(range->max_ip);
212         j = jhash_2words((__force u32)tuple->src.u3.ip,
213                          (__force u32)tuple->dst.u3.ip, 0);
214         *var_ipp = htonl(minip + j % (maxip - minip + 1));
215 }
216
217 /* Manipulate the tuple into the range given.  For NF_INET_POST_ROUTING,
218  * we change the source to map into the range.  For NF_INET_PRE_ROUTING
219  * and NF_INET_LOCAL_OUT, we change the destination to map into the
220  * range.  It might not be possible to get a unique tuple, but we try.
221  * At worst (or if we race), we will end up with a final duplicate in
222  * __ip_conntrack_confirm and drop the packet. */
223 static void
224 get_unique_tuple(struct nf_conntrack_tuple *tuple,
225                  const struct nf_conntrack_tuple *orig_tuple,
226                  const struct nf_nat_range *range,
227                  struct nf_conn *ct,
228                  enum nf_nat_manip_type maniptype)
229 {
230         const struct nf_nat_protocol *proto;
231
232         /* 1) If this srcip/proto/src-proto-part is currently mapped,
233            and that same mapping gives a unique tuple within the given
234            range, use that.
235
236            This is only required for source (ie. NAT/masq) mappings.
237            So far, we don't do local source mappings, so multiple
238            manips not an issue.  */
239         if (maniptype == IP_NAT_MANIP_SRC) {
240                 if (find_appropriate_src(orig_tuple, tuple, range)) {
241                         pr_debug("get_unique_tuple: Found current src map\n");
242                         if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
243                                 if (!nf_nat_used_tuple(tuple, ct))
244                                         return;
245                 }
246         }
247
248         /* 2) Select the least-used IP/proto combination in the given
249            range. */
250         *tuple = *orig_tuple;
251         find_best_ips_proto(tuple, range, ct, maniptype);
252
253         /* 3) The per-protocol part of the manip is made to map into
254            the range to make a unique tuple. */
255
256         rcu_read_lock();
257         proto = __nf_nat_proto_find(orig_tuple->dst.protonum);
258
259         /* Change protocol info to have some randomization */
260         if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) {
261                 proto->unique_tuple(tuple, range, maniptype, ct);
262                 goto out;
263         }
264
265         /* Only bother mapping if it's not already in range and unique */
266         if ((!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
267              proto->in_range(tuple, maniptype, &range->min, &range->max)) &&
268             !nf_nat_used_tuple(tuple, ct))
269                 goto out;
270
271         /* Last change: get protocol to try to obtain unique tuple. */
272         proto->unique_tuple(tuple, range, maniptype, ct);
273 out:
274         rcu_read_unlock();
275 }
276
277 unsigned int
278 nf_nat_setup_info(struct nf_conn *ct,
279                   const struct nf_nat_range *range,
280                   unsigned int hooknum)
281 {
282         struct nf_conntrack_tuple curr_tuple, new_tuple;
283         struct nf_conn_nat *nat;
284         int have_to_hash = !(ct->status & IPS_NAT_DONE_MASK);
285         enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum);
286
287         /* nat helper or nfctnetlink also setup binding */
288         nat = nfct_nat(ct);
289         if (!nat) {
290                 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
291                 if (nat == NULL) {
292                         pr_debug("failed to add NAT extension\n");
293                         return NF_ACCEPT;
294                 }
295         }
296
297         NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING ||
298                      hooknum == NF_INET_POST_ROUTING ||
299                      hooknum == NF_INET_LOCAL_IN ||
300                      hooknum == NF_INET_LOCAL_OUT);
301         BUG_ON(nf_nat_initialized(ct, maniptype));
302
303         /* What we've got will look like inverse of reply. Normally
304            this is what is in the conntrack, except for prior
305            manipulations (future optimization: if num_manips == 0,
306            orig_tp =
307            conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple) */
308         nf_ct_invert_tuplepr(&curr_tuple,
309                              &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
310
311         get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
312
313         if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
314                 struct nf_conntrack_tuple reply;
315
316                 /* Alter conntrack table so will recognize replies. */
317                 nf_ct_invert_tuplepr(&reply, &new_tuple);
318                 nf_conntrack_alter_reply(ct, &reply);
319
320                 /* Non-atomic: we own this at the moment. */
321                 if (maniptype == IP_NAT_MANIP_SRC)
322                         ct->status |= IPS_SRC_NAT;
323                 else
324                         ct->status |= IPS_DST_NAT;
325         }
326
327         /* Place in source hash if this is the first time. */
328         if (have_to_hash) {
329                 unsigned int srchash;
330
331                 srchash = hash_by_src(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
332                 write_lock_bh(&nf_nat_lock);
333                 /* nf_conntrack_alter_reply might re-allocate exntension aera */
334                 nat = nfct_nat(ct);
335                 nat->ct = ct;
336                 hlist_add_head(&nat->bysource, &bysource[srchash]);
337                 write_unlock_bh(&nf_nat_lock);
338         }
339
340         /* It's done. */
341         if (maniptype == IP_NAT_MANIP_DST)
342                 set_bit(IPS_DST_NAT_DONE_BIT, &ct->status);
343         else
344                 set_bit(IPS_SRC_NAT_DONE_BIT, &ct->status);
345
346         return NF_ACCEPT;
347 }
348 EXPORT_SYMBOL(nf_nat_setup_info);
349
350 /* Returns true if succeeded. */
351 static int
352 manip_pkt(u_int16_t proto,
353           struct sk_buff *skb,
354           unsigned int iphdroff,
355           const struct nf_conntrack_tuple *target,
356           enum nf_nat_manip_type maniptype)
357 {
358         struct iphdr *iph;
359         const struct nf_nat_protocol *p;
360
361         if (!skb_make_writable(skb, iphdroff + sizeof(*iph)))
362                 return 0;
363
364         iph = (void *)skb->data + iphdroff;
365
366         /* Manipulate protcol part. */
367
368         /* rcu_read_lock()ed by nf_hook_slow */
369         p = __nf_nat_proto_find(proto);
370         if (!p->manip_pkt(skb, iphdroff, target, maniptype))
371                 return 0;
372
373         iph = (void *)skb->data + iphdroff;
374
375         if (maniptype == IP_NAT_MANIP_SRC) {
376                 csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
377                 iph->saddr = target->src.u3.ip;
378         } else {
379                 csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
380                 iph->daddr = target->dst.u3.ip;
381         }
382         return 1;
383 }
384
385 /* Do packet manipulations according to nf_nat_setup_info. */
386 unsigned int nf_nat_packet(struct nf_conn *ct,
387                            enum ip_conntrack_info ctinfo,
388                            unsigned int hooknum,
389                            struct sk_buff *skb)
390 {
391         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
392         unsigned long statusbit;
393         enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
394
395         if (mtype == IP_NAT_MANIP_SRC)
396                 statusbit = IPS_SRC_NAT;
397         else
398                 statusbit = IPS_DST_NAT;
399
400         /* Invert if this is reply dir. */
401         if (dir == IP_CT_DIR_REPLY)
402                 statusbit ^= IPS_NAT_MASK;
403
404         /* Non-atomic: these bits don't change. */
405         if (ct->status & statusbit) {
406                 struct nf_conntrack_tuple target;
407
408                 /* We are aiming to look like inverse of other direction. */
409                 nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
410
411                 if (!manip_pkt(target.dst.protonum, skb, 0, &target, mtype))
412                         return NF_DROP;
413         }
414         return NF_ACCEPT;
415 }
416 EXPORT_SYMBOL_GPL(nf_nat_packet);
417
418 /* Dir is direction ICMP is coming from (opposite to packet it contains) */
419 int nf_nat_icmp_reply_translation(struct nf_conn *ct,
420                                   enum ip_conntrack_info ctinfo,
421                                   unsigned int hooknum,
422                                   struct sk_buff *skb)
423 {
424         struct {
425                 struct icmphdr icmp;
426                 struct iphdr ip;
427         } *inside;
428         struct nf_conntrack_l4proto *l4proto;
429         struct nf_conntrack_tuple inner, target;
430         int hdrlen = ip_hdrlen(skb);
431         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
432         unsigned long statusbit;
433         enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
434
435         if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
436                 return 0;
437
438         inside = (void *)skb->data + ip_hdrlen(skb);
439
440         /* We're actually going to mangle it beyond trivial checksum
441            adjustment, so make sure the current checksum is correct. */
442         if (nf_ip_checksum(skb, hooknum, hdrlen, 0))
443                 return 0;
444
445         /* Must be RELATED */
446         NF_CT_ASSERT(skb->nfctinfo == IP_CT_RELATED ||
447                      skb->nfctinfo == IP_CT_RELATED+IP_CT_IS_REPLY);
448
449         /* Redirects on non-null nats must be dropped, else they'll
450            start talking to each other without our translation, and be
451            confused... --RR */
452         if (inside->icmp.type == ICMP_REDIRECT) {
453                 /* If NAT isn't finished, assume it and drop. */
454                 if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
455                         return 0;
456
457                 if (ct->status & IPS_NAT_MASK)
458                         return 0;
459         }
460
461         pr_debug("icmp_reply_translation: translating error %p manip %u "
462                  "dir %s\n", skb, manip,
463                  dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY");
464
465         /* rcu_read_lock()ed by nf_hook_slow */
466         l4proto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
467
468         if (!nf_ct_get_tuple(skb,
469                              ip_hdrlen(skb) + sizeof(struct icmphdr),
470                              (ip_hdrlen(skb) +
471                               sizeof(struct icmphdr) + inside->ip.ihl * 4),
472                              (u_int16_t)AF_INET,
473                              inside->ip.protocol,
474                              &inner, l3proto, l4proto))
475                 return 0;
476
477         /* Change inner back to look like incoming packet.  We do the
478            opposite manip on this hook to normal, because it might not
479            pass all hooks (locally-generated ICMP).  Consider incoming
480            packet: PREROUTING (DST manip), routing produces ICMP, goes
481            through POSTROUTING (which must correct the DST manip). */
482         if (!manip_pkt(inside->ip.protocol, skb,
483                        ip_hdrlen(skb) + sizeof(inside->icmp),
484                        &ct->tuplehash[!dir].tuple,
485                        !manip))
486                 return 0;
487
488         if (skb->ip_summed != CHECKSUM_PARTIAL) {
489                 /* Reloading "inside" here since manip_pkt inner. */
490                 inside = (void *)skb->data + ip_hdrlen(skb);
491                 inside->icmp.checksum = 0;
492                 inside->icmp.checksum =
493                         csum_fold(skb_checksum(skb, hdrlen,
494                                                skb->len - hdrlen, 0));
495         }
496
497         /* Change outer to look the reply to an incoming packet
498          * (proto 0 means don't invert per-proto part). */
499         if (manip == IP_NAT_MANIP_SRC)
500                 statusbit = IPS_SRC_NAT;
501         else
502                 statusbit = IPS_DST_NAT;
503
504         /* Invert if this is reply dir. */
505         if (dir == IP_CT_DIR_REPLY)
506                 statusbit ^= IPS_NAT_MASK;
507
508         if (ct->status & statusbit) {
509                 nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
510                 if (!manip_pkt(0, skb, 0, &target, manip))
511                         return 0;
512         }
513
514         return 1;
515 }
516 EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);
517
518 /* Protocol registration. */
519 int nf_nat_protocol_register(const struct nf_nat_protocol *proto)
520 {
521         int ret = 0;
522
523         write_lock_bh(&nf_nat_lock);
524         if (nf_nat_protos[proto->protonum] != &nf_nat_unknown_protocol) {
525                 ret = -EBUSY;
526                 goto out;
527         }
528         rcu_assign_pointer(nf_nat_protos[proto->protonum], proto);
529  out:
530         write_unlock_bh(&nf_nat_lock);
531         return ret;
532 }
533 EXPORT_SYMBOL(nf_nat_protocol_register);
534
535 /* Noone stores the protocol anywhere; simply delete it. */
536 void nf_nat_protocol_unregister(const struct nf_nat_protocol *proto)
537 {
538         write_lock_bh(&nf_nat_lock);
539         rcu_assign_pointer(nf_nat_protos[proto->protonum],
540                            &nf_nat_unknown_protocol);
541         write_unlock_bh(&nf_nat_lock);
542         synchronize_rcu();
543 }
544 EXPORT_SYMBOL(nf_nat_protocol_unregister);
545
546 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
547 int
548 nf_nat_port_range_to_nlattr(struct sk_buff *skb,
549                             const struct nf_nat_range *range)
550 {
551         NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MIN, range->min.tcp.port);
552         NLA_PUT_BE16(skb, CTA_PROTONAT_PORT_MAX, range->max.tcp.port);
553
554         return 0;
555
556 nla_put_failure:
557         return -1;
558 }
559 EXPORT_SYMBOL_GPL(nf_nat_port_nlattr_to_range);
560
561 int
562 nf_nat_port_nlattr_to_range(struct nlattr *tb[], struct nf_nat_range *range)
563 {
564         int ret = 0;
565
566         /* we have to return whether we actually parsed something or not */
567
568         if (tb[CTA_PROTONAT_PORT_MIN]) {
569                 ret = 1;
570                 range->min.tcp.port = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
571         }
572
573         if (!tb[CTA_PROTONAT_PORT_MAX]) {
574                 if (ret)
575                         range->max.tcp.port = range->min.tcp.port;
576         } else {
577                 ret = 1;
578                 range->max.tcp.port = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
579         }
580
581         return ret;
582 }
583 EXPORT_SYMBOL_GPL(nf_nat_port_range_to_nlattr);
584 #endif
585
586 /* Noone using conntrack by the time this called. */
587 static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
588 {
589         struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT);
590
591         if (nat == NULL || nat->ct == NULL)
592                 return;
593
594         NF_CT_ASSERT(nat->ct->status & IPS_NAT_DONE_MASK);
595
596         write_lock_bh(&nf_nat_lock);
597         hlist_del(&nat->bysource);
598         nat->ct = NULL;
599         write_unlock_bh(&nf_nat_lock);
600 }
601
602 static void nf_nat_move_storage(struct nf_conn *conntrack, void *old)
603 {
604         struct nf_conn_nat *new_nat = nf_ct_ext_find(conntrack, NF_CT_EXT_NAT);
605         struct nf_conn_nat *old_nat = (struct nf_conn_nat *)old;
606         struct nf_conn *ct = old_nat->ct;
607
608         if (!ct || !(ct->status & IPS_NAT_DONE_MASK))
609                 return;
610
611         write_lock_bh(&nf_nat_lock);
612         hlist_replace_rcu(&old_nat->bysource, &new_nat->bysource);
613         new_nat->ct = ct;
614         write_unlock_bh(&nf_nat_lock);
615 }
616
617 static struct nf_ct_ext_type nat_extend __read_mostly = {
618         .len            = sizeof(struct nf_conn_nat),
619         .align          = __alignof__(struct nf_conn_nat),
620         .destroy        = nf_nat_cleanup_conntrack,
621         .move           = nf_nat_move_storage,
622         .id             = NF_CT_EXT_NAT,
623         .flags          = NF_CT_EXT_F_PREALLOC,
624 };
625
626 static int __init nf_nat_init(void)
627 {
628         size_t i;
629         int ret;
630
631         ret = nf_ct_extend_register(&nat_extend);
632         if (ret < 0) {
633                 printk(KERN_ERR "nf_nat_core: Unable to register extension\n");
634                 return ret;
635         }
636
637         /* Leave them the same for the moment. */
638         nf_nat_htable_size = nf_conntrack_htable_size;
639
640         bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size,
641                                          &nf_nat_vmalloced);
642         if (!bysource) {
643                 ret = -ENOMEM;
644                 goto cleanup_extend;
645         }
646
647         /* Sew in builtin protocols. */
648         write_lock_bh(&nf_nat_lock);
649         for (i = 0; i < MAX_IP_NAT_PROTO; i++)
650                 rcu_assign_pointer(nf_nat_protos[i], &nf_nat_unknown_protocol);
651         rcu_assign_pointer(nf_nat_protos[IPPROTO_TCP], &nf_nat_protocol_tcp);
652         rcu_assign_pointer(nf_nat_protos[IPPROTO_UDP], &nf_nat_protocol_udp);
653         rcu_assign_pointer(nf_nat_protos[IPPROTO_ICMP], &nf_nat_protocol_icmp);
654         write_unlock_bh(&nf_nat_lock);
655
656         for (i = 0; i < nf_nat_htable_size; i++) {
657                 INIT_HLIST_HEAD(&bysource[i]);
658         }
659
660         /* Initialize fake conntrack so that NAT will skip it */
661         nf_conntrack_untracked.status |= IPS_NAT_DONE_MASK;
662
663         l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET);
664         return 0;
665
666  cleanup_extend:
667         nf_ct_extend_unregister(&nat_extend);
668         return ret;
669 }
670
671 /* Clear NAT section of all conntracks, in case we're loaded again. */
672 static int clean_nat(struct nf_conn *i, void *data)
673 {
674         struct nf_conn_nat *nat = nfct_nat(i);
675
676         if (!nat)
677                 return 0;
678         memset(nat, 0, sizeof(*nat));
679         i->status &= ~(IPS_NAT_MASK | IPS_NAT_DONE_MASK | IPS_SEQ_ADJUST);
680         return 0;
681 }
682
683 static void __exit nf_nat_cleanup(void)
684 {
685         nf_ct_iterate_cleanup(&clean_nat, NULL);
686         synchronize_rcu();
687         nf_ct_free_hashtable(bysource, nf_nat_vmalloced, nf_nat_htable_size);
688         nf_ct_l3proto_put(l3proto);
689         nf_ct_extend_unregister(&nat_extend);
690 }
691
692 MODULE_LICENSE("GPL");
693
694 module_init(nf_nat_init);
695 module_exit(nf_nat_cleanup);