5b194e3c4e254c0140b010033e9d60a150a78e7b
[linux-2.6.git] / net / netfilter / nf_conntrack_core.c
1 /* Connection state tracking for netfilter.  This is separated from,
2    but required by, the NAT layer; it can also be used by an iptables
3    extension. */
4
5 /* (C) 1999-2001 Paul `Rusty' Russell
6  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
7  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  */
13
14 #include <linux/types.h>
15 #include <linux/netfilter.h>
16 #include <linux/module.h>
17 #include <linux/skbuff.h>
18 #include <linux/proc_fs.h>
19 #include <linux/vmalloc.h>
20 #include <linux/stddef.h>
21 #include <linux/slab.h>
22 #include <linux/random.h>
23 #include <linux/jhash.h>
24 #include <linux/err.h>
25 #include <linux/percpu.h>
26 #include <linux/moduleparam.h>
27 #include <linux/notifier.h>
28 #include <linux/kernel.h>
29 #include <linux/netdevice.h>
30 #include <linux/socket.h>
31 #include <linux/mm.h>
32
33 #include <net/netfilter/nf_conntrack.h>
34 #include <net/netfilter/nf_conntrack_l3proto.h>
35 #include <net/netfilter/nf_conntrack_l4proto.h>
36 #include <net/netfilter/nf_conntrack_expect.h>
37 #include <net/netfilter/nf_conntrack_helper.h>
38 #include <net/netfilter/nf_conntrack_core.h>
39 #include <net/netfilter/nf_conntrack_extend.h>
40
41 #define NF_CONNTRACK_VERSION    "0.5.0"
42
43 DEFINE_RWLOCK(nf_conntrack_lock);
44 EXPORT_SYMBOL_GPL(nf_conntrack_lock);
45
46 /* nf_conntrack_standalone needs this */
47 atomic_t nf_conntrack_count = ATOMIC_INIT(0);
48 EXPORT_SYMBOL_GPL(nf_conntrack_count);
49
50 unsigned int nf_conntrack_htable_size __read_mostly;
51 EXPORT_SYMBOL_GPL(nf_conntrack_htable_size);
52
53 int nf_conntrack_max __read_mostly;
54 EXPORT_SYMBOL_GPL(nf_conntrack_max);
55
56 struct hlist_head *nf_conntrack_hash __read_mostly;
57 EXPORT_SYMBOL_GPL(nf_conntrack_hash);
58
59 struct nf_conn nf_conntrack_untracked __read_mostly;
60 EXPORT_SYMBOL_GPL(nf_conntrack_untracked);
61
62 unsigned int nf_ct_log_invalid __read_mostly;
63 HLIST_HEAD(unconfirmed);
64 static int nf_conntrack_vmalloc __read_mostly;
65 static struct kmem_cache *nf_conntrack_cachep __read_mostly;
66 static unsigned int nf_conntrack_next_id;
67
68 DEFINE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat);
69 EXPORT_PER_CPU_SYMBOL(nf_conntrack_stat);
70
71 static int nf_conntrack_hash_rnd_initted;
72 static unsigned int nf_conntrack_hash_rnd;
73
74 static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple,
75                                   unsigned int size, unsigned int rnd)
76 {
77         unsigned int a, b;
78
79         a = jhash2(tuple->src.u3.all, ARRAY_SIZE(tuple->src.u3.all),
80                    (tuple->src.l3num << 16) | tuple->dst.protonum);
81         b = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all),
82                    (tuple->src.u.all << 16) | tuple->dst.u.all);
83
84         return jhash_2words(a, b, rnd) % size;
85 }
86
87 static inline u_int32_t hash_conntrack(const struct nf_conntrack_tuple *tuple)
88 {
89         return __hash_conntrack(tuple, nf_conntrack_htable_size,
90                                 nf_conntrack_hash_rnd);
91 }
92
93 int
94 nf_ct_get_tuple(const struct sk_buff *skb,
95                 unsigned int nhoff,
96                 unsigned int dataoff,
97                 u_int16_t l3num,
98                 u_int8_t protonum,
99                 struct nf_conntrack_tuple *tuple,
100                 const struct nf_conntrack_l3proto *l3proto,
101                 const struct nf_conntrack_l4proto *l4proto)
102 {
103         NF_CT_TUPLE_U_BLANK(tuple);
104
105         tuple->src.l3num = l3num;
106         if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0)
107                 return 0;
108
109         tuple->dst.protonum = protonum;
110         tuple->dst.dir = IP_CT_DIR_ORIGINAL;
111
112         return l4proto->pkt_to_tuple(skb, dataoff, tuple);
113 }
114 EXPORT_SYMBOL_GPL(nf_ct_get_tuple);
115
116 int
117 nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse,
118                    const struct nf_conntrack_tuple *orig,
119                    const struct nf_conntrack_l3proto *l3proto,
120                    const struct nf_conntrack_l4proto *l4proto)
121 {
122         NF_CT_TUPLE_U_BLANK(inverse);
123
124         inverse->src.l3num = orig->src.l3num;
125         if (l3proto->invert_tuple(inverse, orig) == 0)
126                 return 0;
127
128         inverse->dst.dir = !orig->dst.dir;
129
130         inverse->dst.protonum = orig->dst.protonum;
131         return l4proto->invert_tuple(inverse, orig);
132 }
133 EXPORT_SYMBOL_GPL(nf_ct_invert_tuple);
134
135 static void
136 clean_from_lists(struct nf_conn *ct)
137 {
138         pr_debug("clean_from_lists(%p)\n", ct);
139         hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode);
140         hlist_del(&ct->tuplehash[IP_CT_DIR_REPLY].hnode);
141
142         /* Destroy all pending expectations */
143         nf_ct_remove_expectations(ct);
144 }
145
146 static void
147 destroy_conntrack(struct nf_conntrack *nfct)
148 {
149         struct nf_conn *ct = (struct nf_conn *)nfct;
150         struct nf_conntrack_l4proto *l4proto;
151
152         pr_debug("destroy_conntrack(%p)\n", ct);
153         NF_CT_ASSERT(atomic_read(&nfct->use) == 0);
154         NF_CT_ASSERT(!timer_pending(&ct->timeout));
155
156         nf_conntrack_event(IPCT_DESTROY, ct);
157         set_bit(IPS_DYING_BIT, &ct->status);
158
159         /* To make sure we don't get any weird locking issues here:
160          * destroy_conntrack() MUST NOT be called with a write lock
161          * to nf_conntrack_lock!!! -HW */
162         rcu_read_lock();
163         l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num,
164                                        ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
165         if (l4proto && l4proto->destroy)
166                 l4proto->destroy(ct);
167
168         nf_ct_ext_destroy(ct);
169
170         rcu_read_unlock();
171
172         write_lock_bh(&nf_conntrack_lock);
173         /* Expectations will have been removed in clean_from_lists,
174          * except TFTP can create an expectation on the first packet,
175          * before connection is in the list, so we need to clean here,
176          * too. */
177         nf_ct_remove_expectations(ct);
178
179         /* We overload first tuple to link into unconfirmed list. */
180         if (!nf_ct_is_confirmed(ct)) {
181                 BUG_ON(hlist_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode));
182                 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode);
183         }
184
185         NF_CT_STAT_INC(delete);
186         write_unlock_bh(&nf_conntrack_lock);
187
188         if (ct->master)
189                 nf_ct_put(ct->master);
190
191         pr_debug("destroy_conntrack: returning ct=%p to slab\n", ct);
192         nf_conntrack_free(ct);
193 }
194
195 static void death_by_timeout(unsigned long ul_conntrack)
196 {
197         struct nf_conn *ct = (void *)ul_conntrack;
198         struct nf_conn_help *help = nfct_help(ct);
199         struct nf_conntrack_helper *helper;
200
201         if (help) {
202                 rcu_read_lock();
203                 helper = rcu_dereference(help->helper);
204                 if (helper && helper->destroy)
205                         helper->destroy(ct);
206                 rcu_read_unlock();
207         }
208
209         write_lock_bh(&nf_conntrack_lock);
210         /* Inside lock so preempt is disabled on module removal path.
211          * Otherwise we can get spurious warnings. */
212         NF_CT_STAT_INC(delete_list);
213         clean_from_lists(ct);
214         write_unlock_bh(&nf_conntrack_lock);
215         nf_ct_put(ct);
216 }
217
218 struct nf_conntrack_tuple_hash *
219 __nf_conntrack_find(const struct nf_conntrack_tuple *tuple,
220                     const struct nf_conn *ignored_conntrack)
221 {
222         struct nf_conntrack_tuple_hash *h;
223         struct hlist_node *n;
224         unsigned int hash = hash_conntrack(tuple);
225
226         hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) {
227                 if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack &&
228                     nf_ct_tuple_equal(tuple, &h->tuple)) {
229                         NF_CT_STAT_INC(found);
230                         return h;
231                 }
232                 NF_CT_STAT_INC(searched);
233         }
234
235         return NULL;
236 }
237 EXPORT_SYMBOL_GPL(__nf_conntrack_find);
238
239 /* Find a connection corresponding to a tuple. */
240 struct nf_conntrack_tuple_hash *
241 nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple)
242 {
243         struct nf_conntrack_tuple_hash *h;
244
245         read_lock_bh(&nf_conntrack_lock);
246         h = __nf_conntrack_find(tuple, NULL);
247         if (h)
248                 atomic_inc(&nf_ct_tuplehash_to_ctrack(h)->ct_general.use);
249         read_unlock_bh(&nf_conntrack_lock);
250
251         return h;
252 }
253 EXPORT_SYMBOL_GPL(nf_conntrack_find_get);
254
255 static void __nf_conntrack_hash_insert(struct nf_conn *ct,
256                                        unsigned int hash,
257                                        unsigned int repl_hash)
258 {
259         ct->id = ++nf_conntrack_next_id;
260         hlist_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode,
261                        &nf_conntrack_hash[hash]);
262         hlist_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnode,
263                        &nf_conntrack_hash[repl_hash]);
264 }
265
266 void nf_conntrack_hash_insert(struct nf_conn *ct)
267 {
268         unsigned int hash, repl_hash;
269
270         hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
271         repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
272
273         write_lock_bh(&nf_conntrack_lock);
274         __nf_conntrack_hash_insert(ct, hash, repl_hash);
275         write_unlock_bh(&nf_conntrack_lock);
276 }
277 EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert);
278
279 /* Confirm a connection given skb; places it in hash table */
280 int
281 __nf_conntrack_confirm(struct sk_buff **pskb)
282 {
283         unsigned int hash, repl_hash;
284         struct nf_conntrack_tuple_hash *h;
285         struct nf_conn *ct;
286         struct nf_conn_help *help;
287         struct hlist_node *n;
288         enum ip_conntrack_info ctinfo;
289
290         ct = nf_ct_get(*pskb, &ctinfo);
291
292         /* ipt_REJECT uses nf_conntrack_attach to attach related
293            ICMP/TCP RST packets in other direction.  Actual packet
294            which created connection will be IP_CT_NEW or for an
295            expected connection, IP_CT_RELATED. */
296         if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
297                 return NF_ACCEPT;
298
299         hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
300         repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
301
302         /* We're not in hash table, and we refuse to set up related
303            connections for unconfirmed conns.  But packet copies and
304            REJECT will give spurious warnings here. */
305         /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */
306
307         /* No external references means noone else could have
308            confirmed us. */
309         NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
310         pr_debug("Confirming conntrack %p\n", ct);
311
312         write_lock_bh(&nf_conntrack_lock);
313
314         /* See if there's one in the list already, including reverse:
315            NAT could have grabbed it without realizing, since we're
316            not in the hash.  If there is, we lost race. */
317         hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode)
318                 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
319                                       &h->tuple))
320                         goto out;
321         hlist_for_each_entry(h, n, &nf_conntrack_hash[repl_hash], hnode)
322                 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
323                                       &h->tuple))
324                         goto out;
325
326         /* Remove from unconfirmed list */
327         hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode);
328
329         __nf_conntrack_hash_insert(ct, hash, repl_hash);
330         /* Timer relative to confirmation time, not original
331            setting time, otherwise we'd get timer wrap in
332            weird delay cases. */
333         ct->timeout.expires += jiffies;
334         add_timer(&ct->timeout);
335         atomic_inc(&ct->ct_general.use);
336         set_bit(IPS_CONFIRMED_BIT, &ct->status);
337         NF_CT_STAT_INC(insert);
338         write_unlock_bh(&nf_conntrack_lock);
339         help = nfct_help(ct);
340         if (help && help->helper)
341                 nf_conntrack_event_cache(IPCT_HELPER, *pskb);
342 #ifdef CONFIG_NF_NAT_NEEDED
343         if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) ||
344             test_bit(IPS_DST_NAT_DONE_BIT, &ct->status))
345                 nf_conntrack_event_cache(IPCT_NATINFO, *pskb);
346 #endif
347         nf_conntrack_event_cache(master_ct(ct) ?
348                                  IPCT_RELATED : IPCT_NEW, *pskb);
349         return NF_ACCEPT;
350
351 out:
352         NF_CT_STAT_INC(insert_failed);
353         write_unlock_bh(&nf_conntrack_lock);
354         return NF_DROP;
355 }
356 EXPORT_SYMBOL_GPL(__nf_conntrack_confirm);
357
358 /* Returns true if a connection correspondings to the tuple (required
359    for NAT). */
360 int
361 nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
362                          const struct nf_conn *ignored_conntrack)
363 {
364         struct nf_conntrack_tuple_hash *h;
365
366         read_lock_bh(&nf_conntrack_lock);
367         h = __nf_conntrack_find(tuple, ignored_conntrack);
368         read_unlock_bh(&nf_conntrack_lock);
369
370         return h != NULL;
371 }
372 EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken);
373
374 #define NF_CT_EVICTION_RANGE    8
375
376 /* There's a small race here where we may free a just-assured
377    connection.  Too bad: we're in trouble anyway. */
378 static int early_drop(unsigned int hash)
379 {
380         /* Use oldest entry, which is roughly LRU */
381         struct nf_conntrack_tuple_hash *h;
382         struct nf_conn *ct = NULL, *tmp;
383         struct hlist_node *n;
384         unsigned int i, cnt = 0;
385         int dropped = 0;
386
387         read_lock_bh(&nf_conntrack_lock);
388         for (i = 0; i < nf_conntrack_htable_size; i++) {
389                 hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) {
390                         tmp = nf_ct_tuplehash_to_ctrack(h);
391                         if (!test_bit(IPS_ASSURED_BIT, &tmp->status))
392                                 ct = tmp;
393                         cnt++;
394                 }
395                 if (ct || cnt >= NF_CT_EVICTION_RANGE)
396                         break;
397                 hash = (hash + 1) % nf_conntrack_htable_size;
398         }
399         if (ct)
400                 atomic_inc(&ct->ct_general.use);
401         read_unlock_bh(&nf_conntrack_lock);
402
403         if (!ct)
404                 return dropped;
405
406         if (del_timer(&ct->timeout)) {
407                 death_by_timeout((unsigned long)ct);
408                 dropped = 1;
409                 NF_CT_STAT_INC_ATOMIC(early_drop);
410         }
411         nf_ct_put(ct);
412         return dropped;
413 }
414
415 struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig,
416                                    const struct nf_conntrack_tuple *repl)
417 {
418         struct nf_conn *conntrack = NULL;
419
420         if (unlikely(!nf_conntrack_hash_rnd_initted)) {
421                 get_random_bytes(&nf_conntrack_hash_rnd, 4);
422                 nf_conntrack_hash_rnd_initted = 1;
423         }
424
425         /* We don't want any race condition at early drop stage */
426         atomic_inc(&nf_conntrack_count);
427
428         if (nf_conntrack_max
429             && atomic_read(&nf_conntrack_count) > nf_conntrack_max) {
430                 unsigned int hash = hash_conntrack(orig);
431                 if (!early_drop(hash)) {
432                         atomic_dec(&nf_conntrack_count);
433                         if (net_ratelimit())
434                                 printk(KERN_WARNING
435                                        "nf_conntrack: table full, dropping"
436                                        " packet.\n");
437                         return ERR_PTR(-ENOMEM);
438                 }
439         }
440
441         conntrack = kmem_cache_zalloc(nf_conntrack_cachep, GFP_ATOMIC);
442         if (conntrack == NULL) {
443                 pr_debug("nf_conntrack_alloc: Can't alloc conntrack.\n");
444                 atomic_dec(&nf_conntrack_count);
445                 return ERR_PTR(-ENOMEM);
446         }
447
448         atomic_set(&conntrack->ct_general.use, 1);
449         conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig;
450         conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl;
451         /* Don't set timer yet: wait for confirmation */
452         setup_timer(&conntrack->timeout, death_by_timeout,
453                     (unsigned long)conntrack);
454
455         return conntrack;
456 }
457 EXPORT_SYMBOL_GPL(nf_conntrack_alloc);
458
459 void nf_conntrack_free(struct nf_conn *conntrack)
460 {
461         nf_ct_ext_free(conntrack);
462         kmem_cache_free(nf_conntrack_cachep, conntrack);
463         atomic_dec(&nf_conntrack_count);
464 }
465 EXPORT_SYMBOL_GPL(nf_conntrack_free);
466
467 /* Allocate a new conntrack: we return -ENOMEM if classification
468    failed due to stress.  Otherwise it really is unclassifiable. */
469 static struct nf_conntrack_tuple_hash *
470 init_conntrack(const struct nf_conntrack_tuple *tuple,
471                struct nf_conntrack_l3proto *l3proto,
472                struct nf_conntrack_l4proto *l4proto,
473                struct sk_buff *skb,
474                unsigned int dataoff)
475 {
476         struct nf_conn *conntrack;
477         struct nf_conn_help *help;
478         struct nf_conntrack_tuple repl_tuple;
479         struct nf_conntrack_expect *exp;
480
481         if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) {
482                 pr_debug("Can't invert tuple.\n");
483                 return NULL;
484         }
485
486         conntrack = nf_conntrack_alloc(tuple, &repl_tuple);
487         if (conntrack == NULL || IS_ERR(conntrack)) {
488                 pr_debug("Can't allocate conntrack.\n");
489                 return (struct nf_conntrack_tuple_hash *)conntrack;
490         }
491
492         if (!l4proto->new(conntrack, skb, dataoff)) {
493                 nf_conntrack_free(conntrack);
494                 pr_debug("init conntrack: can't track with proto module\n");
495                 return NULL;
496         }
497
498         write_lock_bh(&nf_conntrack_lock);
499         exp = nf_ct_find_expectation(tuple);
500         if (exp) {
501                 pr_debug("conntrack: expectation arrives ct=%p exp=%p\n",
502                          conntrack, exp);
503                 /* Welcome, Mr. Bond.  We've been expecting you... */
504                 __set_bit(IPS_EXPECTED_BIT, &conntrack->status);
505                 conntrack->master = exp->master;
506                 if (exp->helper) {
507                         help = nf_ct_helper_ext_add(conntrack, GFP_ATOMIC);
508                         if (help)
509                                 rcu_assign_pointer(help->helper, exp->helper);
510                 }
511
512 #ifdef CONFIG_NF_CONNTRACK_MARK
513                 conntrack->mark = exp->master->mark;
514 #endif
515 #ifdef CONFIG_NF_CONNTRACK_SECMARK
516                 conntrack->secmark = exp->master->secmark;
517 #endif
518                 nf_conntrack_get(&conntrack->master->ct_general);
519                 NF_CT_STAT_INC(expect_new);
520         } else {
521                 struct nf_conntrack_helper *helper;
522
523                 helper = __nf_ct_helper_find(&repl_tuple);
524                 if (helper) {
525                         help = nf_ct_helper_ext_add(conntrack, GFP_ATOMIC);
526                         if (help)
527                                 rcu_assign_pointer(help->helper, helper);
528                 }
529                 NF_CT_STAT_INC(new);
530         }
531
532         /* Overload tuple linked list to put us in unconfirmed list. */
533         hlist_add_head(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].hnode,
534                        &unconfirmed);
535
536         write_unlock_bh(&nf_conntrack_lock);
537
538         if (exp) {
539                 if (exp->expectfn)
540                         exp->expectfn(conntrack, exp);
541                 nf_ct_expect_put(exp);
542         }
543
544         return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL];
545 }
546
547 /* On success, returns conntrack ptr, sets skb->nfct and ctinfo */
548 static inline struct nf_conn *
549 resolve_normal_ct(struct sk_buff *skb,
550                   unsigned int dataoff,
551                   u_int16_t l3num,
552                   u_int8_t protonum,
553                   struct nf_conntrack_l3proto *l3proto,
554                   struct nf_conntrack_l4proto *l4proto,
555                   int *set_reply,
556                   enum ip_conntrack_info *ctinfo)
557 {
558         struct nf_conntrack_tuple tuple;
559         struct nf_conntrack_tuple_hash *h;
560         struct nf_conn *ct;
561
562         if (!nf_ct_get_tuple(skb, skb_network_offset(skb),
563                              dataoff, l3num, protonum, &tuple, l3proto,
564                              l4proto)) {
565                 pr_debug("resolve_normal_ct: Can't get tuple\n");
566                 return NULL;
567         }
568
569         /* look for tuple match */
570         h = nf_conntrack_find_get(&tuple);
571         if (!h) {
572                 h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff);
573                 if (!h)
574                         return NULL;
575                 if (IS_ERR(h))
576                         return (void *)h;
577         }
578         ct = nf_ct_tuplehash_to_ctrack(h);
579
580         /* It exists; we have (non-exclusive) reference. */
581         if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) {
582                 *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY;
583                 /* Please set reply bit if this packet OK */
584                 *set_reply = 1;
585         } else {
586                 /* Once we've had two way comms, always ESTABLISHED. */
587                 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
588                         pr_debug("nf_conntrack_in: normal packet for %p\n", ct);
589                         *ctinfo = IP_CT_ESTABLISHED;
590                 } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) {
591                         pr_debug("nf_conntrack_in: related packet for %p\n",
592                                  ct);
593                         *ctinfo = IP_CT_RELATED;
594                 } else {
595                         pr_debug("nf_conntrack_in: new packet for %p\n", ct);
596                         *ctinfo = IP_CT_NEW;
597                 }
598                 *set_reply = 0;
599         }
600         skb->nfct = &ct->ct_general;
601         skb->nfctinfo = *ctinfo;
602         return ct;
603 }
604
605 unsigned int
606 nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb)
607 {
608         struct nf_conn *ct;
609         enum ip_conntrack_info ctinfo;
610         struct nf_conntrack_l3proto *l3proto;
611         struct nf_conntrack_l4proto *l4proto;
612         unsigned int dataoff;
613         u_int8_t protonum;
614         int set_reply = 0;
615         int ret;
616
617         /* Previously seen (loopback or untracked)?  Ignore. */
618         if ((*pskb)->nfct) {
619                 NF_CT_STAT_INC_ATOMIC(ignore);
620                 return NF_ACCEPT;
621         }
622
623         /* rcu_read_lock()ed by nf_hook_slow */
624         l3proto = __nf_ct_l3proto_find((u_int16_t)pf);
625         ret = l3proto->get_l4proto(*pskb, skb_network_offset(*pskb),
626                                    &dataoff, &protonum);
627         if (ret <= 0) {
628                 pr_debug("not prepared to track yet or error occured\n");
629                 NF_CT_STAT_INC_ATOMIC(error);
630                 NF_CT_STAT_INC_ATOMIC(invalid);
631                 return -ret;
632         }
633
634         l4proto = __nf_ct_l4proto_find((u_int16_t)pf, protonum);
635
636         /* It may be an special packet, error, unclean...
637          * inverse of the return code tells to the netfilter
638          * core what to do with the packet. */
639         if (l4proto->error != NULL &&
640             (ret = l4proto->error(*pskb, dataoff, &ctinfo, pf, hooknum)) <= 0) {
641                 NF_CT_STAT_INC_ATOMIC(error);
642                 NF_CT_STAT_INC_ATOMIC(invalid);
643                 return -ret;
644         }
645
646         ct = resolve_normal_ct(*pskb, dataoff, pf, protonum, l3proto, l4proto,
647                                &set_reply, &ctinfo);
648         if (!ct) {
649                 /* Not valid part of a connection */
650                 NF_CT_STAT_INC_ATOMIC(invalid);
651                 return NF_ACCEPT;
652         }
653
654         if (IS_ERR(ct)) {
655                 /* Too stressed to deal. */
656                 NF_CT_STAT_INC_ATOMIC(drop);
657                 return NF_DROP;
658         }
659
660         NF_CT_ASSERT((*pskb)->nfct);
661
662         ret = l4proto->packet(ct, *pskb, dataoff, ctinfo, pf, hooknum);
663         if (ret < 0) {
664                 /* Invalid: inverse of the return code tells
665                  * the netfilter core what to do */
666                 pr_debug("nf_conntrack_in: Can't track with proto module\n");
667                 nf_conntrack_put((*pskb)->nfct);
668                 (*pskb)->nfct = NULL;
669                 NF_CT_STAT_INC_ATOMIC(invalid);
670                 return -ret;
671         }
672
673         if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
674                 nf_conntrack_event_cache(IPCT_STATUS, *pskb);
675
676         return ret;
677 }
678 EXPORT_SYMBOL_GPL(nf_conntrack_in);
679
680 int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
681                          const struct nf_conntrack_tuple *orig)
682 {
683         int ret;
684
685         rcu_read_lock();
686         ret = nf_ct_invert_tuple(inverse, orig,
687                                  __nf_ct_l3proto_find(orig->src.l3num),
688                                  __nf_ct_l4proto_find(orig->src.l3num,
689                                                       orig->dst.protonum));
690         rcu_read_unlock();
691         return ret;
692 }
693 EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr);
694
695 /* Alter reply tuple (maybe alter helper).  This is for NAT, and is
696    implicitly racy: see __nf_conntrack_confirm */
697 void nf_conntrack_alter_reply(struct nf_conn *ct,
698                               const struct nf_conntrack_tuple *newreply)
699 {
700         struct nf_conn_help *help = nfct_help(ct);
701         struct nf_conntrack_helper *helper;
702
703         write_lock_bh(&nf_conntrack_lock);
704         /* Should be unconfirmed, so not in hash table yet */
705         NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
706
707         pr_debug("Altering reply tuple of %p to ", ct);
708         NF_CT_DUMP_TUPLE(newreply);
709
710         ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
711         if (ct->master || (help && help->expecting != 0))
712                 goto out;
713
714         helper = __nf_ct_helper_find(newreply);
715         if (helper == NULL) {
716                 if (help)
717                         rcu_assign_pointer(help->helper, NULL);
718                 goto out;
719         }
720
721         if (help == NULL) {
722                 help = nf_ct_helper_ext_add(ct, GFP_ATOMIC);
723                 if (help == NULL)
724                         goto out;
725         } else {
726                 memset(&help->help, 0, sizeof(help->help));
727         }
728
729         rcu_assign_pointer(help->helper, helper);
730 out:
731         write_unlock_bh(&nf_conntrack_lock);
732 }
733 EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);
734
735 /* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */
736 void __nf_ct_refresh_acct(struct nf_conn *ct,
737                           enum ip_conntrack_info ctinfo,
738                           const struct sk_buff *skb,
739                           unsigned long extra_jiffies,
740                           int do_acct)
741 {
742         int event = 0;
743
744         NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct);
745         NF_CT_ASSERT(skb);
746
747         write_lock_bh(&nf_conntrack_lock);
748
749         /* Only update if this is not a fixed timeout */
750         if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) {
751                 write_unlock_bh(&nf_conntrack_lock);
752                 return;
753         }
754
755         /* If not in hash table, timer will not be active yet */
756         if (!nf_ct_is_confirmed(ct)) {
757                 ct->timeout.expires = extra_jiffies;
758                 event = IPCT_REFRESH;
759         } else {
760                 unsigned long newtime = jiffies + extra_jiffies;
761
762                 /* Only update the timeout if the new timeout is at least
763                    HZ jiffies from the old timeout. Need del_timer for race
764                    avoidance (may already be dying). */
765                 if (newtime - ct->timeout.expires >= HZ
766                     && del_timer(&ct->timeout)) {
767                         ct->timeout.expires = newtime;
768                         add_timer(&ct->timeout);
769                         event = IPCT_REFRESH;
770                 }
771         }
772
773 #ifdef CONFIG_NF_CT_ACCT
774         if (do_acct) {
775                 ct->counters[CTINFO2DIR(ctinfo)].packets++;
776                 ct->counters[CTINFO2DIR(ctinfo)].bytes +=
777                         skb->len - skb_network_offset(skb);
778
779                 if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000)
780                     || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000))
781                         event |= IPCT_COUNTER_FILLING;
782         }
783 #endif
784
785         write_unlock_bh(&nf_conntrack_lock);
786
787         /* must be unlocked when calling event cache */
788         if (event)
789                 nf_conntrack_event_cache(event, skb);
790 }
791 EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct);
792
793 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
794
795 #include <linux/netfilter/nfnetlink.h>
796 #include <linux/netfilter/nfnetlink_conntrack.h>
797 #include <linux/mutex.h>
798
799
800 /* Generic function for tcp/udp/sctp/dccp and alike. This needs to be
801  * in ip_conntrack_core, since we don't want the protocols to autoload
802  * or depend on ctnetlink */
803 int nf_ct_port_tuple_to_nfattr(struct sk_buff *skb,
804                                const struct nf_conntrack_tuple *tuple)
805 {
806         NFA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t),
807                 &tuple->src.u.tcp.port);
808         NFA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t),
809                 &tuple->dst.u.tcp.port);
810         return 0;
811
812 nfattr_failure:
813         return -1;
814 }
815 EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nfattr);
816
817 static const size_t cta_min_proto[CTA_PROTO_MAX] = {
818         [CTA_PROTO_SRC_PORT-1]  = sizeof(u_int16_t),
819         [CTA_PROTO_DST_PORT-1]  = sizeof(u_int16_t)
820 };
821
822 int nf_ct_port_nfattr_to_tuple(struct nfattr *tb[],
823                                struct nf_conntrack_tuple *t)
824 {
825         if (!tb[CTA_PROTO_SRC_PORT-1] || !tb[CTA_PROTO_DST_PORT-1])
826                 return -EINVAL;
827
828         if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
829                 return -EINVAL;
830
831         t->src.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_SRC_PORT-1]);
832         t->dst.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_DST_PORT-1]);
833
834         return 0;
835 }
836 EXPORT_SYMBOL_GPL(nf_ct_port_nfattr_to_tuple);
837 #endif
838
839 /* Used by ipt_REJECT and ip6t_REJECT. */
840 void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb)
841 {
842         struct nf_conn *ct;
843         enum ip_conntrack_info ctinfo;
844
845         /* This ICMP is in reverse direction to the packet which caused it */
846         ct = nf_ct_get(skb, &ctinfo);
847         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
848                 ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY;
849         else
850                 ctinfo = IP_CT_RELATED;
851
852         /* Attach to new skbuff, and increment count */
853         nskb->nfct = &ct->ct_general;
854         nskb->nfctinfo = ctinfo;
855         nf_conntrack_get(nskb->nfct);
856 }
857 EXPORT_SYMBOL_GPL(__nf_conntrack_attach);
858
859 static inline int
860 do_iter(const struct nf_conntrack_tuple_hash *i,
861         int (*iter)(struct nf_conn *i, void *data),
862         void *data)
863 {
864         return iter(nf_ct_tuplehash_to_ctrack(i), data);
865 }
866
867 /* Bring out ya dead! */
868 static struct nf_conn *
869 get_next_corpse(int (*iter)(struct nf_conn *i, void *data),
870                 void *data, unsigned int *bucket)
871 {
872         struct nf_conntrack_tuple_hash *h;
873         struct nf_conn *ct;
874         struct hlist_node *n;
875
876         write_lock_bh(&nf_conntrack_lock);
877         for (; *bucket < nf_conntrack_htable_size; (*bucket)++) {
878                 hlist_for_each_entry(h, n, &nf_conntrack_hash[*bucket], hnode) {
879                         ct = nf_ct_tuplehash_to_ctrack(h);
880                         if (iter(ct, data))
881                                 goto found;
882                 }
883         }
884         hlist_for_each_entry(h, n, &unconfirmed, hnode) {
885                 ct = nf_ct_tuplehash_to_ctrack(h);
886                 if (iter(ct, data))
887                         set_bit(IPS_DYING_BIT, &ct->status);
888         }
889         write_unlock_bh(&nf_conntrack_lock);
890         return NULL;
891 found:
892         atomic_inc(&ct->ct_general.use);
893         write_unlock_bh(&nf_conntrack_lock);
894         return ct;
895 }
896
897 void
898 nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data)
899 {
900         struct nf_conn *ct;
901         unsigned int bucket = 0;
902
903         while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) {
904                 /* Time to push up daises... */
905                 if (del_timer(&ct->timeout))
906                         death_by_timeout((unsigned long)ct);
907                 /* ... else the timer will get him soon. */
908
909                 nf_ct_put(ct);
910         }
911 }
912 EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup);
913
914 static int kill_all(struct nf_conn *i, void *data)
915 {
916         return 1;
917 }
918
919 void nf_ct_free_hashtable(struct hlist_head *hash, int vmalloced, int size)
920 {
921         if (vmalloced)
922                 vfree(hash);
923         else
924                 free_pages((unsigned long)hash,
925                            get_order(sizeof(struct hlist_head) * size));
926 }
927 EXPORT_SYMBOL_GPL(nf_ct_free_hashtable);
928
929 void nf_conntrack_flush(void)
930 {
931         nf_ct_iterate_cleanup(kill_all, NULL);
932 }
933 EXPORT_SYMBOL_GPL(nf_conntrack_flush);
934
935 /* Mishearing the voices in his head, our hero wonders how he's
936    supposed to kill the mall. */
937 void nf_conntrack_cleanup(void)
938 {
939         rcu_assign_pointer(ip_ct_attach, NULL);
940
941         /* This makes sure all current packets have passed through
942            netfilter framework.  Roll on, two-stage module
943            delete... */
944         synchronize_net();
945
946         nf_ct_event_cache_flush();
947  i_see_dead_people:
948         nf_conntrack_flush();
949         if (atomic_read(&nf_conntrack_count) != 0) {
950                 schedule();
951                 goto i_see_dead_people;
952         }
953         /* wait until all references to nf_conntrack_untracked are dropped */
954         while (atomic_read(&nf_conntrack_untracked.ct_general.use) > 1)
955                 schedule();
956
957         rcu_assign_pointer(nf_ct_destroy, NULL);
958
959         kmem_cache_destroy(nf_conntrack_cachep);
960         nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc,
961                              nf_conntrack_htable_size);
962
963         nf_conntrack_proto_fini();
964         nf_conntrack_helper_fini();
965         nf_conntrack_expect_fini();
966 }
967
968 struct hlist_head *nf_ct_alloc_hashtable(int *sizep, int *vmalloced)
969 {
970         struct hlist_head *hash;
971         unsigned int size, i;
972
973         *vmalloced = 0;
974
975         size = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_head));
976         hash = (void*)__get_free_pages(GFP_KERNEL,
977                                        get_order(sizeof(struct hlist_head)
978                                                  * size));
979         if (!hash) {
980                 *vmalloced = 1;
981                 printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n");
982                 hash = vmalloc(sizeof(struct hlist_head) * size);
983         }
984
985         if (hash)
986                 for (i = 0; i < size; i++)
987                         INIT_HLIST_HEAD(&hash[i]);
988
989         return hash;
990 }
991 EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable);
992
993 int set_hashsize(const char *val, struct kernel_param *kp)
994 {
995         int i, bucket, hashsize, vmalloced;
996         int old_vmalloced, old_size;
997         int rnd;
998         struct hlist_head *hash, *old_hash;
999         struct nf_conntrack_tuple_hash *h;
1000
1001         /* On boot, we can set this without any fancy locking. */
1002         if (!nf_conntrack_htable_size)
1003                 return param_set_uint(val, kp);
1004
1005         hashsize = simple_strtol(val, NULL, 0);
1006         if (!hashsize)
1007                 return -EINVAL;
1008
1009         hash = nf_ct_alloc_hashtable(&hashsize, &vmalloced);
1010         if (!hash)
1011                 return -ENOMEM;
1012
1013         /* We have to rehahs for the new table anyway, so we also can
1014          * use a newrandom seed */
1015         get_random_bytes(&rnd, 4);
1016
1017         write_lock_bh(&nf_conntrack_lock);
1018         for (i = 0; i < nf_conntrack_htable_size; i++) {
1019                 while (!hlist_empty(&nf_conntrack_hash[i])) {
1020                         h = hlist_entry(nf_conntrack_hash[i].first,
1021                                         struct nf_conntrack_tuple_hash, hnode);
1022                         hlist_del(&h->hnode);
1023                         bucket = __hash_conntrack(&h->tuple, hashsize, rnd);
1024                         hlist_add_head(&h->hnode, &hash[bucket]);
1025                 }
1026         }
1027         old_size = nf_conntrack_htable_size;
1028         old_vmalloced = nf_conntrack_vmalloc;
1029         old_hash = nf_conntrack_hash;
1030
1031         nf_conntrack_htable_size = hashsize;
1032         nf_conntrack_vmalloc = vmalloced;
1033         nf_conntrack_hash = hash;
1034         nf_conntrack_hash_rnd = rnd;
1035         write_unlock_bh(&nf_conntrack_lock);
1036
1037         nf_ct_free_hashtable(old_hash, old_vmalloced, old_size);
1038         return 0;
1039 }
1040
1041 module_param_call(hashsize, set_hashsize, param_get_uint,
1042                   &nf_conntrack_htable_size, 0600);
1043
1044 int __init nf_conntrack_init(void)
1045 {
1046         int max_factor = 8;
1047         int ret;
1048
1049         /* Idea from tcp.c: use 1/16384 of memory.  On i386: 32MB
1050          * machine has 512 buckets. >= 1GB machines have 16384 buckets. */
1051         if (!nf_conntrack_htable_size) {
1052                 nf_conntrack_htable_size
1053                         = (((num_physpages << PAGE_SHIFT) / 16384)
1054                            / sizeof(struct hlist_head));
1055                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
1056                         nf_conntrack_htable_size = 16384;
1057                 if (nf_conntrack_htable_size < 32)
1058                         nf_conntrack_htable_size = 32;
1059
1060                 /* Use a max. factor of four by default to get the same max as
1061                  * with the old struct list_heads. When a table size is given
1062                  * we use the old value of 8 to avoid reducing the max.
1063                  * entries. */
1064                 max_factor = 4;
1065         }
1066         nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size,
1067                                                   &nf_conntrack_vmalloc);
1068         if (!nf_conntrack_hash) {
1069                 printk(KERN_ERR "Unable to create nf_conntrack_hash\n");
1070                 goto err_out;
1071         }
1072
1073         nf_conntrack_max = max_factor * nf_conntrack_htable_size;
1074
1075         printk("nf_conntrack version %s (%u buckets, %d max)\n",
1076                NF_CONNTRACK_VERSION, nf_conntrack_htable_size,
1077                nf_conntrack_max);
1078
1079         nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
1080                                                 sizeof(struct nf_conn),
1081                                                 0, 0, NULL, NULL);
1082         if (!nf_conntrack_cachep) {
1083                 printk(KERN_ERR "Unable to create nf_conn slab cache\n");
1084                 goto err_free_hash;
1085         }
1086
1087         ret = nf_conntrack_proto_init();
1088         if (ret < 0)
1089                 goto err_free_conntrack_slab;
1090
1091         ret = nf_conntrack_expect_init();
1092         if (ret < 0)
1093                 goto out_fini_proto;
1094
1095         ret = nf_conntrack_helper_init();
1096         if (ret < 0)
1097                 goto out_fini_expect;
1098
1099         /* For use by REJECT target */
1100         rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach);
1101         rcu_assign_pointer(nf_ct_destroy, destroy_conntrack);
1102
1103         /* Set up fake conntrack:
1104             - to never be deleted, not in any hashes */
1105         atomic_set(&nf_conntrack_untracked.ct_general.use, 1);
1106         /*  - and look it like as a confirmed connection */
1107         set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status);
1108
1109         return ret;
1110
1111 out_fini_expect:
1112         nf_conntrack_expect_fini();
1113 out_fini_proto:
1114         nf_conntrack_proto_fini();
1115 err_free_conntrack_slab:
1116         kmem_cache_destroy(nf_conntrack_cachep);
1117 err_free_hash:
1118         nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_vmalloc,
1119                              nf_conntrack_htable_size);
1120 err_out:
1121         return -ENOMEM;
1122 }