992d0ef31fa39028f037dc598f7ad20a8dc54c51
[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 #if 0
44 #define DEBUGP printk
45 #else
46 #define DEBUGP(format, args...)
47 #endif
48
49 DEFINE_RWLOCK(nf_conntrack_lock);
50 EXPORT_SYMBOL_GPL(nf_conntrack_lock);
51
52 /* nf_conntrack_standalone needs this */
53 atomic_t nf_conntrack_count = ATOMIC_INIT(0);
54 EXPORT_SYMBOL_GPL(nf_conntrack_count);
55
56 unsigned int nf_conntrack_htable_size __read_mostly;
57 EXPORT_SYMBOL_GPL(nf_conntrack_htable_size);
58
59 int nf_conntrack_max __read_mostly;
60 EXPORT_SYMBOL_GPL(nf_conntrack_max);
61
62 struct hlist_head *nf_conntrack_hash __read_mostly;
63 EXPORT_SYMBOL_GPL(nf_conntrack_hash);
64
65 struct nf_conn nf_conntrack_untracked __read_mostly;
66 EXPORT_SYMBOL_GPL(nf_conntrack_untracked);
67
68 unsigned int nf_ct_log_invalid __read_mostly;
69 HLIST_HEAD(unconfirmed);
70 static int nf_conntrack_vmalloc __read_mostly;
71 static struct kmem_cache *nf_conntrack_cachep __read_mostly;
72 static unsigned int nf_conntrack_next_id;
73
74 DEFINE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat);
75 EXPORT_PER_CPU_SYMBOL(nf_conntrack_stat);
76
77 static int nf_conntrack_hash_rnd_initted;
78 static unsigned int nf_conntrack_hash_rnd;
79
80 static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple,
81                                   unsigned int size, unsigned int rnd)
82 {
83         unsigned int a, b;
84
85         a = jhash2(tuple->src.u3.all, ARRAY_SIZE(tuple->src.u3.all),
86                    (tuple->src.l3num << 16) | tuple->dst.protonum);
87         b = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all),
88                    (tuple->src.u.all << 16) | tuple->dst.u.all);
89
90         return jhash_2words(a, b, rnd) % size;
91 }
92
93 static inline u_int32_t hash_conntrack(const struct nf_conntrack_tuple *tuple)
94 {
95         return __hash_conntrack(tuple, nf_conntrack_htable_size,
96                                 nf_conntrack_hash_rnd);
97 }
98
99 int
100 nf_ct_get_tuple(const struct sk_buff *skb,
101                 unsigned int nhoff,
102                 unsigned int dataoff,
103                 u_int16_t l3num,
104                 u_int8_t protonum,
105                 struct nf_conntrack_tuple *tuple,
106                 const struct nf_conntrack_l3proto *l3proto,
107                 const struct nf_conntrack_l4proto *l4proto)
108 {
109         NF_CT_TUPLE_U_BLANK(tuple);
110
111         tuple->src.l3num = l3num;
112         if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0)
113                 return 0;
114
115         tuple->dst.protonum = protonum;
116         tuple->dst.dir = IP_CT_DIR_ORIGINAL;
117
118         return l4proto->pkt_to_tuple(skb, dataoff, tuple);
119 }
120 EXPORT_SYMBOL_GPL(nf_ct_get_tuple);
121
122 int
123 nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse,
124                    const struct nf_conntrack_tuple *orig,
125                    const struct nf_conntrack_l3proto *l3proto,
126                    const struct nf_conntrack_l4proto *l4proto)
127 {
128         NF_CT_TUPLE_U_BLANK(inverse);
129
130         inverse->src.l3num = orig->src.l3num;
131         if (l3proto->invert_tuple(inverse, orig) == 0)
132                 return 0;
133
134         inverse->dst.dir = !orig->dst.dir;
135
136         inverse->dst.protonum = orig->dst.protonum;
137         return l4proto->invert_tuple(inverse, orig);
138 }
139 EXPORT_SYMBOL_GPL(nf_ct_invert_tuple);
140
141 static void
142 clean_from_lists(struct nf_conn *ct)
143 {
144         DEBUGP("clean_from_lists(%p)\n", ct);
145         hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode);
146         hlist_del(&ct->tuplehash[IP_CT_DIR_REPLY].hnode);
147
148         /* Destroy all pending expectations */
149         nf_ct_remove_expectations(ct);
150 }
151
152 static void
153 destroy_conntrack(struct nf_conntrack *nfct)
154 {
155         struct nf_conn *ct = (struct nf_conn *)nfct;
156         struct nf_conntrack_l4proto *l4proto;
157
158         DEBUGP("destroy_conntrack(%p)\n", ct);
159         NF_CT_ASSERT(atomic_read(&nfct->use) == 0);
160         NF_CT_ASSERT(!timer_pending(&ct->timeout));
161
162         nf_conntrack_event(IPCT_DESTROY, ct);
163         set_bit(IPS_DYING_BIT, &ct->status);
164
165         /* To make sure we don't get any weird locking issues here:
166          * destroy_conntrack() MUST NOT be called with a write lock
167          * to nf_conntrack_lock!!! -HW */
168         rcu_read_lock();
169         l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num,
170                                        ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
171         if (l4proto && l4proto->destroy)
172                 l4proto->destroy(ct);
173
174         nf_ct_ext_destroy(ct);
175
176         rcu_read_unlock();
177
178         write_lock_bh(&nf_conntrack_lock);
179         /* Expectations will have been removed in clean_from_lists,
180          * except TFTP can create an expectation on the first packet,
181          * before connection is in the list, so we need to clean here,
182          * too. */
183         nf_ct_remove_expectations(ct);
184
185         /* We overload first tuple to link into unconfirmed list. */
186         if (!nf_ct_is_confirmed(ct)) {
187                 BUG_ON(hlist_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode));
188                 hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode);
189         }
190
191         NF_CT_STAT_INC(delete);
192         write_unlock_bh(&nf_conntrack_lock);
193
194         if (ct->master)
195                 nf_ct_put(ct->master);
196
197         DEBUGP("destroy_conntrack: returning ct=%p to slab\n", ct);
198         nf_conntrack_free(ct);
199 }
200
201 static void death_by_timeout(unsigned long ul_conntrack)
202 {
203         struct nf_conn *ct = (void *)ul_conntrack;
204         struct nf_conn_help *help = nfct_help(ct);
205         struct nf_conntrack_helper *helper;
206
207         if (help) {
208                 rcu_read_lock();
209                 helper = rcu_dereference(help->helper);
210                 if (helper && helper->destroy)
211                         helper->destroy(ct);
212                 rcu_read_unlock();
213         }
214
215         write_lock_bh(&nf_conntrack_lock);
216         /* Inside lock so preempt is disabled on module removal path.
217          * Otherwise we can get spurious warnings. */
218         NF_CT_STAT_INC(delete_list);
219         clean_from_lists(ct);
220         write_unlock_bh(&nf_conntrack_lock);
221         nf_ct_put(ct);
222 }
223
224 struct nf_conntrack_tuple_hash *
225 __nf_conntrack_find(const struct nf_conntrack_tuple *tuple,
226                     const struct nf_conn *ignored_conntrack)
227 {
228         struct nf_conntrack_tuple_hash *h;
229         struct hlist_node *n;
230         unsigned int hash = hash_conntrack(tuple);
231
232         hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode) {
233                 if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack &&
234                     nf_ct_tuple_equal(tuple, &h->tuple)) {
235                         NF_CT_STAT_INC(found);
236                         return h;
237                 }
238                 NF_CT_STAT_INC(searched);
239         }
240
241         return NULL;
242 }
243 EXPORT_SYMBOL_GPL(__nf_conntrack_find);
244
245 /* Find a connection corresponding to a tuple. */
246 struct nf_conntrack_tuple_hash *
247 nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple,
248                       const struct nf_conn *ignored_conntrack)
249 {
250         struct nf_conntrack_tuple_hash *h;
251
252         read_lock_bh(&nf_conntrack_lock);
253         h = __nf_conntrack_find(tuple, ignored_conntrack);
254         if (h)
255                 atomic_inc(&nf_ct_tuplehash_to_ctrack(h)->ct_general.use);
256         read_unlock_bh(&nf_conntrack_lock);
257
258         return h;
259 }
260 EXPORT_SYMBOL_GPL(nf_conntrack_find_get);
261
262 static void __nf_conntrack_hash_insert(struct nf_conn *ct,
263                                        unsigned int hash,
264                                        unsigned int repl_hash)
265 {
266         ct->id = ++nf_conntrack_next_id;
267         hlist_add_head(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode,
268                        &nf_conntrack_hash[hash]);
269         hlist_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnode,
270                        &nf_conntrack_hash[repl_hash]);
271 }
272
273 void nf_conntrack_hash_insert(struct nf_conn *ct)
274 {
275         unsigned int hash, repl_hash;
276
277         hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
278         repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
279
280         write_lock_bh(&nf_conntrack_lock);
281         __nf_conntrack_hash_insert(ct, hash, repl_hash);
282         write_unlock_bh(&nf_conntrack_lock);
283 }
284 EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert);
285
286 /* Confirm a connection given skb; places it in hash table */
287 int
288 __nf_conntrack_confirm(struct sk_buff **pskb)
289 {
290         unsigned int hash, repl_hash;
291         struct nf_conntrack_tuple_hash *h;
292         struct nf_conn *ct;
293         struct nf_conn_help *help;
294         struct hlist_node *n;
295         enum ip_conntrack_info ctinfo;
296
297         ct = nf_ct_get(*pskb, &ctinfo);
298
299         /* ipt_REJECT uses nf_conntrack_attach to attach related
300            ICMP/TCP RST packets in other direction.  Actual packet
301            which created connection will be IP_CT_NEW or for an
302            expected connection, IP_CT_RELATED. */
303         if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
304                 return NF_ACCEPT;
305
306         hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
307         repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
308
309         /* We're not in hash table, and we refuse to set up related
310            connections for unconfirmed conns.  But packet copies and
311            REJECT will give spurious warnings here. */
312         /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */
313
314         /* No external references means noone else could have
315            confirmed us. */
316         NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
317         DEBUGP("Confirming conntrack %p\n", ct);
318
319         write_lock_bh(&nf_conntrack_lock);
320
321         /* See if there's one in the list already, including reverse:
322            NAT could have grabbed it without realizing, since we're
323            not in the hash.  If there is, we lost race. */
324         hlist_for_each_entry(h, n, &nf_conntrack_hash[hash], hnode)
325                 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
326                                       &h->tuple))
327                         goto out;
328         hlist_for_each_entry(h, n, &nf_conntrack_hash[repl_hash], hnode)
329                 if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
330                                       &h->tuple))
331                         goto out;
332
333         /* Remove from unconfirmed list */
334         hlist_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnode);
335
336         __nf_conntrack_hash_insert(ct, hash, repl_hash);
337         /* Timer relative to confirmation time, not original
338            setting time, otherwise we'd get timer wrap in
339            weird delay cases. */
340         ct->timeout.expires += jiffies;
341         add_timer(&ct->timeout);
342         atomic_inc(&ct->ct_general.use);
343         set_bit(IPS_CONFIRMED_BIT, &ct->status);
344         NF_CT_STAT_INC(insert);
345         write_unlock_bh(&nf_conntrack_lock);
346         help = nfct_help(ct);
347         if (help && help->helper)
348                 nf_conntrack_event_cache(IPCT_HELPER, *pskb);
349 #ifdef CONFIG_NF_NAT_NEEDED
350         if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) ||
351             test_bit(IPS_DST_NAT_DONE_BIT, &ct->status))
352                 nf_conntrack_event_cache(IPCT_NATINFO, *pskb);
353 #endif
354         nf_conntrack_event_cache(master_ct(ct) ?
355                                  IPCT_RELATED : IPCT_NEW, *pskb);
356         return NF_ACCEPT;
357
358 out:
359         NF_CT_STAT_INC(insert_failed);
360         write_unlock_bh(&nf_conntrack_lock);
361         return NF_DROP;
362 }
363 EXPORT_SYMBOL_GPL(__nf_conntrack_confirm);
364
365 /* Returns true if a connection correspondings to the tuple (required
366    for NAT). */
367 int
368 nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
369                          const struct nf_conn *ignored_conntrack)
370 {
371         struct nf_conntrack_tuple_hash *h;
372
373         read_lock_bh(&nf_conntrack_lock);
374         h = __nf_conntrack_find(tuple, ignored_conntrack);
375         read_unlock_bh(&nf_conntrack_lock);
376
377         return h != NULL;
378 }
379 EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken);
380
381 /* There's a small race here where we may free a just-assured
382    connection.  Too bad: we're in trouble anyway. */
383 static int early_drop(struct hlist_head *chain)
384 {
385         /* Use oldest entry, which is roughly LRU */
386         struct nf_conntrack_tuple_hash *h;
387         struct nf_conn *ct = NULL, *tmp;
388         struct hlist_node *n;
389         int dropped = 0;
390
391         read_lock_bh(&nf_conntrack_lock);
392         hlist_for_each_entry(h, n, chain, hnode) {
393                 tmp = nf_ct_tuplehash_to_ctrack(h);
394                 if (!test_bit(IPS_ASSURED_BIT, &tmp->status))
395                         ct = tmp;
396         }
397         if (ct)
398                 atomic_inc(&ct->ct_general.use);
399         read_unlock_bh(&nf_conntrack_lock);
400
401         if (!ct)
402                 return dropped;
403
404         if (del_timer(&ct->timeout)) {
405                 death_by_timeout((unsigned long)ct);
406                 dropped = 1;
407                 NF_CT_STAT_INC_ATOMIC(early_drop);
408         }
409         nf_ct_put(ct);
410         return dropped;
411 }
412
413 struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig,
414                                    const struct nf_conntrack_tuple *repl)
415 {
416         struct nf_conn *conntrack = NULL;
417
418         if (unlikely(!nf_conntrack_hash_rnd_initted)) {
419                 get_random_bytes(&nf_conntrack_hash_rnd, 4);
420                 nf_conntrack_hash_rnd_initted = 1;
421         }
422
423         /* We don't want any race condition at early drop stage */
424         atomic_inc(&nf_conntrack_count);
425
426         if (nf_conntrack_max
427             && atomic_read(&nf_conntrack_count) > nf_conntrack_max) {
428                 unsigned int hash = hash_conntrack(orig);
429                 /* Try dropping from this hash chain. */
430                 if (!early_drop(&nf_conntrack_hash[hash])) {
431                         atomic_dec(&nf_conntrack_count);
432                         if (net_ratelimit())
433                                 printk(KERN_WARNING
434                                        "nf_conntrack: table full, dropping"
435                                        " packet.\n");
436                         return ERR_PTR(-ENOMEM);
437                 }
438         }
439
440         conntrack = kmem_cache_zalloc(nf_conntrack_cachep, GFP_ATOMIC);
441         if (conntrack == NULL) {
442                 DEBUGP("nf_conntrack_alloc: Can't alloc conntrack.\n");
443                 atomic_dec(&nf_conntrack_count);
444                 return ERR_PTR(-ENOMEM);
445         }
446
447         atomic_set(&conntrack->ct_general.use, 1);
448         conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig;
449         conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl;
450         /* Don't set timer yet: wait for confirmation */
451         setup_timer(&conntrack->timeout, death_by_timeout,
452                     (unsigned long)conntrack);
453
454         return conntrack;
455 }
456 EXPORT_SYMBOL_GPL(nf_conntrack_alloc);
457
458 void nf_conntrack_free(struct nf_conn *conntrack)
459 {
460         nf_ct_ext_free(conntrack);
461         kmem_cache_free(nf_conntrack_cachep, conntrack);
462         atomic_dec(&nf_conntrack_count);
463 }
464 EXPORT_SYMBOL_GPL(nf_conntrack_free);
465
466 /* Allocate a new conntrack: we return -ENOMEM if classification
467    failed due to stress.  Otherwise it really is unclassifiable. */
468 static struct nf_conntrack_tuple_hash *
469 init_conntrack(const struct nf_conntrack_tuple *tuple,
470                struct nf_conntrack_l3proto *l3proto,
471                struct nf_conntrack_l4proto *l4proto,
472                struct sk_buff *skb,
473                unsigned int dataoff)
474 {
475         struct nf_conn *conntrack;
476         struct nf_conn_help *help;
477         struct nf_conntrack_tuple repl_tuple;
478         struct nf_conntrack_expect *exp;
479
480         if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) {
481                 DEBUGP("Can't invert tuple.\n");
482                 return NULL;
483         }
484
485         conntrack = nf_conntrack_alloc(tuple, &repl_tuple);
486         if (conntrack == NULL || IS_ERR(conntrack)) {
487                 DEBUGP("Can't allocate conntrack.\n");
488                 return (struct nf_conntrack_tuple_hash *)conntrack;
489         }
490
491         if (!l4proto->new(conntrack, skb, dataoff)) {
492                 nf_conntrack_free(conntrack);
493                 DEBUGP("init conntrack: can't track with proto module\n");
494                 return NULL;
495         }
496
497         write_lock_bh(&nf_conntrack_lock);
498         exp = find_expectation(tuple);
499         if (exp) {
500                 DEBUGP("conntrack: expectation arrives ct=%p exp=%p\n",
501                         conntrack, exp);
502                 /* Welcome, Mr. Bond.  We've been expecting you... */
503                 __set_bit(IPS_EXPECTED_BIT, &conntrack->status);
504                 conntrack->master = exp->master;
505                 if (exp->helper) {
506                         help = nf_ct_ext_add(conntrack, NF_CT_EXT_HELPER,
507                                              GFP_ATOMIC);
508                         if (help)
509                                 rcu_assign_pointer(help->helper, exp->helper);
510                         else
511                                 DEBUGP("failed to add helper extension area");
512                 }
513
514 #ifdef CONFIG_NF_CONNTRACK_MARK
515                 conntrack->mark = exp->master->mark;
516 #endif
517 #ifdef CONFIG_NF_CONNTRACK_SECMARK
518                 conntrack->secmark = exp->master->secmark;
519 #endif
520                 nf_conntrack_get(&conntrack->master->ct_general);
521                 NF_CT_STAT_INC(expect_new);
522         } else {
523                 struct nf_conntrack_helper *helper;
524
525                 helper = __nf_ct_helper_find(&repl_tuple);
526                 if (helper) {
527                         help = nf_ct_ext_add(conntrack, NF_CT_EXT_HELPER,
528                                              GFP_ATOMIC);
529                         if (help)
530                                 /* not in hash table yet, so not strictly
531                                    necessary */
532                                 rcu_assign_pointer(help->helper, helper);
533                         else
534                                 DEBUGP("failed to add helper extension area");
535                 }
536                 NF_CT_STAT_INC(new);
537         }
538
539         /* Overload tuple linked list to put us in unconfirmed list. */
540         hlist_add_head(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].hnode,
541                        &unconfirmed);
542
543         write_unlock_bh(&nf_conntrack_lock);
544
545         if (exp) {
546                 if (exp->expectfn)
547                         exp->expectfn(conntrack, exp);
548                 nf_conntrack_expect_put(exp);
549         }
550
551         return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL];
552 }
553
554 /* On success, returns conntrack ptr, sets skb->nfct and ctinfo */
555 static inline struct nf_conn *
556 resolve_normal_ct(struct sk_buff *skb,
557                   unsigned int dataoff,
558                   u_int16_t l3num,
559                   u_int8_t protonum,
560                   struct nf_conntrack_l3proto *l3proto,
561                   struct nf_conntrack_l4proto *l4proto,
562                   int *set_reply,
563                   enum ip_conntrack_info *ctinfo)
564 {
565         struct nf_conntrack_tuple tuple;
566         struct nf_conntrack_tuple_hash *h;
567         struct nf_conn *ct;
568
569         if (!nf_ct_get_tuple(skb, skb_network_offset(skb),
570                              dataoff, l3num, protonum, &tuple, l3proto,
571                              l4proto)) {
572                 DEBUGP("resolve_normal_ct: Can't get tuple\n");
573                 return NULL;
574         }
575
576         /* look for tuple match */
577         h = nf_conntrack_find_get(&tuple, NULL);
578         if (!h) {
579                 h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff);
580                 if (!h)
581                         return NULL;
582                 if (IS_ERR(h))
583                         return (void *)h;
584         }
585         ct = nf_ct_tuplehash_to_ctrack(h);
586
587         /* It exists; we have (non-exclusive) reference. */
588         if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) {
589                 *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY;
590                 /* Please set reply bit if this packet OK */
591                 *set_reply = 1;
592         } else {
593                 /* Once we've had two way comms, always ESTABLISHED. */
594                 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
595                         DEBUGP("nf_conntrack_in: normal packet for %p\n", ct);
596                         *ctinfo = IP_CT_ESTABLISHED;
597                 } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) {
598                         DEBUGP("nf_conntrack_in: related packet for %p\n", ct);
599                         *ctinfo = IP_CT_RELATED;
600                 } else {
601                         DEBUGP("nf_conntrack_in: new packet for %p\n", ct);
602                         *ctinfo = IP_CT_NEW;
603                 }
604                 *set_reply = 0;
605         }
606         skb->nfct = &ct->ct_general;
607         skb->nfctinfo = *ctinfo;
608         return ct;
609 }
610
611 unsigned int
612 nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb)
613 {
614         struct nf_conn *ct;
615         enum ip_conntrack_info ctinfo;
616         struct nf_conntrack_l3proto *l3proto;
617         struct nf_conntrack_l4proto *l4proto;
618         unsigned int dataoff;
619         u_int8_t protonum;
620         int set_reply = 0;
621         int ret;
622
623         /* Previously seen (loopback or untracked)?  Ignore. */
624         if ((*pskb)->nfct) {
625                 NF_CT_STAT_INC_ATOMIC(ignore);
626                 return NF_ACCEPT;
627         }
628
629         /* rcu_read_lock()ed by nf_hook_slow */
630         l3proto = __nf_ct_l3proto_find((u_int16_t)pf);
631
632         if ((ret = l3proto->prepare(pskb, hooknum, &dataoff, &protonum)) <= 0) {
633                 DEBUGP("not prepared to track yet or error occured\n");
634                 return -ret;
635         }
636
637         l4proto = __nf_ct_l4proto_find((u_int16_t)pf, protonum);
638
639         /* It may be an special packet, error, unclean...
640          * inverse of the return code tells to the netfilter
641          * core what to do with the packet. */
642         if (l4proto->error != NULL &&
643             (ret = l4proto->error(*pskb, dataoff, &ctinfo, pf, hooknum)) <= 0) {
644                 NF_CT_STAT_INC_ATOMIC(error);
645                 NF_CT_STAT_INC_ATOMIC(invalid);
646                 return -ret;
647         }
648
649         ct = resolve_normal_ct(*pskb, dataoff, pf, protonum, l3proto, l4proto,
650                                &set_reply, &ctinfo);
651         if (!ct) {
652                 /* Not valid part of a connection */
653                 NF_CT_STAT_INC_ATOMIC(invalid);
654                 return NF_ACCEPT;
655         }
656
657         if (IS_ERR(ct)) {
658                 /* Too stressed to deal. */
659                 NF_CT_STAT_INC_ATOMIC(drop);
660                 return NF_DROP;
661         }
662
663         NF_CT_ASSERT((*pskb)->nfct);
664
665         ret = l4proto->packet(ct, *pskb, dataoff, ctinfo, pf, hooknum);
666         if (ret < 0) {
667                 /* Invalid: inverse of the return code tells
668                  * the netfilter core what to do */
669                 DEBUGP("nf_conntrack_in: Can't track with proto module\n");
670                 nf_conntrack_put((*pskb)->nfct);
671                 (*pskb)->nfct = NULL;
672                 NF_CT_STAT_INC_ATOMIC(invalid);
673                 return -ret;
674         }
675
676         if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
677                 nf_conntrack_event_cache(IPCT_STATUS, *pskb);
678
679         return ret;
680 }
681 EXPORT_SYMBOL_GPL(nf_conntrack_in);
682
683 int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse,
684                          const struct nf_conntrack_tuple *orig)
685 {
686         int ret;
687
688         rcu_read_lock();
689         ret = nf_ct_invert_tuple(inverse, orig,
690                                  __nf_ct_l3proto_find(orig->src.l3num),
691                                  __nf_ct_l4proto_find(orig->src.l3num,
692                                                       orig->dst.protonum));
693         rcu_read_unlock();
694         return ret;
695 }
696 EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr);
697
698 /* Alter reply tuple (maybe alter helper).  This is for NAT, and is
699    implicitly racy: see __nf_conntrack_confirm */
700 void nf_conntrack_alter_reply(struct nf_conn *ct,
701                               const struct nf_conntrack_tuple *newreply)
702 {
703         struct nf_conn_help *help = nfct_help(ct);
704         struct nf_conntrack_helper *helper;
705
706         write_lock_bh(&nf_conntrack_lock);
707         /* Should be unconfirmed, so not in hash table yet */
708         NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
709
710         DEBUGP("Altering reply tuple of %p to ", ct);
711         NF_CT_DUMP_TUPLE(newreply);
712
713         ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
714         if (ct->master || (help && help->expecting != 0))
715                 goto out;
716
717         helper = __nf_ct_helper_find(newreply);
718         if (helper == NULL) {
719                 if (help)
720                         rcu_assign_pointer(help->helper, NULL);
721                 goto out;
722         }
723
724         if (help == NULL) {
725                 help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, GFP_ATOMIC);
726                 if (help == NULL) {
727                         DEBUGP("failed to add helper extension area");
728                         goto out;
729                 }
730         } else {
731                 memset(&help->help, 0, sizeof(help->help));
732         }
733
734         rcu_assign_pointer(help->helper, helper);
735 out:
736         write_unlock_bh(&nf_conntrack_lock);
737 }
738 EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);
739
740 /* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */
741 void __nf_ct_refresh_acct(struct nf_conn *ct,
742                           enum ip_conntrack_info ctinfo,
743                           const struct sk_buff *skb,
744                           unsigned long extra_jiffies,
745                           int do_acct)
746 {
747         int event = 0;
748
749         NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct);
750         NF_CT_ASSERT(skb);
751
752         write_lock_bh(&nf_conntrack_lock);
753
754         /* Only update if this is not a fixed timeout */
755         if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) {
756                 write_unlock_bh(&nf_conntrack_lock);
757                 return;
758         }
759
760         /* If not in hash table, timer will not be active yet */
761         if (!nf_ct_is_confirmed(ct)) {
762                 ct->timeout.expires = extra_jiffies;
763                 event = IPCT_REFRESH;
764         } else {
765                 unsigned long newtime = jiffies + extra_jiffies;
766
767                 /* Only update the timeout if the new timeout is at least
768                    HZ jiffies from the old timeout. Need del_timer for race
769                    avoidance (may already be dying). */
770                 if (newtime - ct->timeout.expires >= HZ
771                     && del_timer(&ct->timeout)) {
772                         ct->timeout.expires = newtime;
773                         add_timer(&ct->timeout);
774                         event = IPCT_REFRESH;
775                 }
776         }
777
778 #ifdef CONFIG_NF_CT_ACCT
779         if (do_acct) {
780                 ct->counters[CTINFO2DIR(ctinfo)].packets++;
781                 ct->counters[CTINFO2DIR(ctinfo)].bytes +=
782                         skb->len - skb_network_offset(skb);
783
784                 if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000)
785                     || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000))
786                         event |= IPCT_COUNTER_FILLING;
787         }
788 #endif
789
790         write_unlock_bh(&nf_conntrack_lock);
791
792         /* must be unlocked when calling event cache */
793         if (event)
794                 nf_conntrack_event_cache(event, skb);
795 }
796 EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct);
797
798 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
799
800 #include <linux/netfilter/nfnetlink.h>
801 #include <linux/netfilter/nfnetlink_conntrack.h>
802 #include <linux/mutex.h>
803
804
805 /* Generic function for tcp/udp/sctp/dccp and alike. This needs to be
806  * in ip_conntrack_core, since we don't want the protocols to autoload
807  * or depend on ctnetlink */
808 int nf_ct_port_tuple_to_nfattr(struct sk_buff *skb,
809                                const struct nf_conntrack_tuple *tuple)
810 {
811         NFA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t),
812                 &tuple->src.u.tcp.port);
813         NFA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t),
814                 &tuple->dst.u.tcp.port);
815         return 0;
816
817 nfattr_failure:
818         return -1;
819 }
820 EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nfattr);
821
822 static const size_t cta_min_proto[CTA_PROTO_MAX] = {
823         [CTA_PROTO_SRC_PORT-1]  = sizeof(u_int16_t),
824         [CTA_PROTO_DST_PORT-1]  = sizeof(u_int16_t)
825 };
826
827 int nf_ct_port_nfattr_to_tuple(struct nfattr *tb[],
828                                struct nf_conntrack_tuple *t)
829 {
830         if (!tb[CTA_PROTO_SRC_PORT-1] || !tb[CTA_PROTO_DST_PORT-1])
831                 return -EINVAL;
832
833         if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
834                 return -EINVAL;
835
836         t->src.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_SRC_PORT-1]);
837         t->dst.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_DST_PORT-1]);
838
839         return 0;
840 }
841 EXPORT_SYMBOL_GPL(nf_ct_port_nfattr_to_tuple);
842 #endif
843
844 /* Used by ipt_REJECT and ip6t_REJECT. */
845 void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb)
846 {
847         struct nf_conn *ct;
848         enum ip_conntrack_info ctinfo;
849
850         /* This ICMP is in reverse direction to the packet which caused it */
851         ct = nf_ct_get(skb, &ctinfo);
852         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
853                 ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY;
854         else
855                 ctinfo = IP_CT_RELATED;
856
857         /* Attach to new skbuff, and increment count */
858         nskb->nfct = &ct->ct_general;
859         nskb->nfctinfo = ctinfo;
860         nf_conntrack_get(nskb->nfct);
861 }
862 EXPORT_SYMBOL_GPL(__nf_conntrack_attach);
863
864 static inline int
865 do_iter(const struct nf_conntrack_tuple_hash *i,
866         int (*iter)(struct nf_conn *i, void *data),
867         void *data)
868 {
869         return iter(nf_ct_tuplehash_to_ctrack(i), data);
870 }
871
872 /* Bring out ya dead! */
873 static struct nf_conn *
874 get_next_corpse(int (*iter)(struct nf_conn *i, void *data),
875                 void *data, unsigned int *bucket)
876 {
877         struct nf_conntrack_tuple_hash *h;
878         struct nf_conn *ct;
879         struct hlist_node *n;
880
881         write_lock_bh(&nf_conntrack_lock);
882         for (; *bucket < nf_conntrack_htable_size; (*bucket)++) {
883                 hlist_for_each_entry(h, n, &nf_conntrack_hash[*bucket], hnode) {
884                         ct = nf_ct_tuplehash_to_ctrack(h);
885                         if (iter(ct, data))
886                                 goto found;
887                 }
888         }
889         hlist_for_each_entry(h, n, &unconfirmed, hnode) {
890                 ct = nf_ct_tuplehash_to_ctrack(h);
891                 if (iter(ct, data))
892                         set_bit(IPS_DYING_BIT, &ct->status);
893         }
894         write_unlock_bh(&nf_conntrack_lock);
895         return NULL;
896 found:
897         atomic_inc(&ct->ct_general.use);
898         write_unlock_bh(&nf_conntrack_lock);
899         return ct;
900 }
901
902 void
903 nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data)
904 {
905         struct nf_conn *ct;
906         unsigned int bucket = 0;
907
908         while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) {
909                 /* Time to push up daises... */
910                 if (del_timer(&ct->timeout))
911                         death_by_timeout((unsigned long)ct);
912                 /* ... else the timer will get him soon. */
913
914                 nf_ct_put(ct);
915         }
916 }
917 EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup);
918
919 static int kill_all(struct nf_conn *i, void *data)
920 {
921         return 1;
922 }
923
924 static void free_conntrack_hash(struct hlist_head *hash, int vmalloced,
925                                 int size)
926 {
927         if (vmalloced)
928                 vfree(hash);
929         else
930                 free_pages((unsigned long)hash,
931                            get_order(sizeof(struct hlist_head) * size));
932 }
933
934 void nf_conntrack_flush(void)
935 {
936         nf_ct_iterate_cleanup(kill_all, NULL);
937 }
938 EXPORT_SYMBOL_GPL(nf_conntrack_flush);
939
940 /* Mishearing the voices in his head, our hero wonders how he's
941    supposed to kill the mall. */
942 void nf_conntrack_cleanup(void)
943 {
944         rcu_assign_pointer(ip_ct_attach, NULL);
945
946         /* This makes sure all current packets have passed through
947            netfilter framework.  Roll on, two-stage module
948            delete... */
949         synchronize_net();
950
951         nf_ct_event_cache_flush();
952  i_see_dead_people:
953         nf_conntrack_flush();
954         if (atomic_read(&nf_conntrack_count) != 0) {
955                 schedule();
956                 goto i_see_dead_people;
957         }
958         /* wait until all references to nf_conntrack_untracked are dropped */
959         while (atomic_read(&nf_conntrack_untracked.ct_general.use) > 1)
960                 schedule();
961
962         rcu_assign_pointer(nf_ct_destroy, NULL);
963
964         kmem_cache_destroy(nf_conntrack_cachep);
965         kmem_cache_destroy(nf_conntrack_expect_cachep);
966         free_conntrack_hash(nf_conntrack_hash, nf_conntrack_vmalloc,
967                             nf_conntrack_htable_size);
968
969         nf_conntrack_proto_fini();
970         nf_conntrack_helper_fini();
971 }
972
973 static struct hlist_head *alloc_hashtable(int *sizep, int *vmalloced)
974 {
975         struct hlist_head *hash;
976         unsigned int size, i;
977
978         *vmalloced = 0;
979
980         size = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_head));
981         hash = (void*)__get_free_pages(GFP_KERNEL,
982                                        get_order(sizeof(struct hlist_head)
983                                                  * size));
984         if (!hash) {
985                 *vmalloced = 1;
986                 printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n");
987                 hash = vmalloc(sizeof(struct hlist_head) * size);
988         }
989
990         if (hash)
991                 for (i = 0; i < size; i++)
992                         INIT_HLIST_HEAD(&hash[i]);
993
994         return hash;
995 }
996
997 int set_hashsize(const char *val, struct kernel_param *kp)
998 {
999         int i, bucket, hashsize, vmalloced;
1000         int old_vmalloced, old_size;
1001         int rnd;
1002         struct hlist_head *hash, *old_hash;
1003         struct nf_conntrack_tuple_hash *h;
1004
1005         /* On boot, we can set this without any fancy locking. */
1006         if (!nf_conntrack_htable_size)
1007                 return param_set_uint(val, kp);
1008
1009         hashsize = simple_strtol(val, NULL, 0);
1010         if (!hashsize)
1011                 return -EINVAL;
1012
1013         hash = alloc_hashtable(&hashsize, &vmalloced);
1014         if (!hash)
1015                 return -ENOMEM;
1016
1017         /* We have to rehahs for the new table anyway, so we also can
1018          * use a newrandom seed */
1019         get_random_bytes(&rnd, 4);
1020
1021         write_lock_bh(&nf_conntrack_lock);
1022         for (i = 0; i < nf_conntrack_htable_size; i++) {
1023                 while (!hlist_empty(&nf_conntrack_hash[i])) {
1024                         h = hlist_entry(nf_conntrack_hash[i].first,
1025                                         struct nf_conntrack_tuple_hash, hnode);
1026                         hlist_del(&h->hnode);
1027                         bucket = __hash_conntrack(&h->tuple, hashsize, rnd);
1028                         hlist_add_head(&h->hnode, &hash[bucket]);
1029                 }
1030         }
1031         old_size = nf_conntrack_htable_size;
1032         old_vmalloced = nf_conntrack_vmalloc;
1033         old_hash = nf_conntrack_hash;
1034
1035         nf_conntrack_htable_size = hashsize;
1036         nf_conntrack_vmalloc = vmalloced;
1037         nf_conntrack_hash = hash;
1038         nf_conntrack_hash_rnd = rnd;
1039         write_unlock_bh(&nf_conntrack_lock);
1040
1041         free_conntrack_hash(old_hash, old_vmalloced, old_size);
1042         return 0;
1043 }
1044
1045 module_param_call(hashsize, set_hashsize, param_get_uint,
1046                   &nf_conntrack_htable_size, 0600);
1047
1048 int __init nf_conntrack_init(void)
1049 {
1050         int max_factor = 8;
1051         int ret;
1052
1053         /* Idea from tcp.c: use 1/16384 of memory.  On i386: 32MB
1054          * machine has 512 buckets. >= 1GB machines have 16384 buckets. */
1055         if (!nf_conntrack_htable_size) {
1056                 nf_conntrack_htable_size
1057                         = (((num_physpages << PAGE_SHIFT) / 16384)
1058                            / sizeof(struct hlist_head));
1059                 if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
1060                         nf_conntrack_htable_size = 16384;
1061                 if (nf_conntrack_htable_size < 32)
1062                         nf_conntrack_htable_size = 32;
1063
1064                 /* Use a max. factor of four by default to get the same max as
1065                  * with the old struct list_heads. When a table size is given
1066                  * we use the old value of 8 to avoid reducing the max.
1067                  * entries. */
1068                 max_factor = 4;
1069         }
1070         nf_conntrack_hash = alloc_hashtable(&nf_conntrack_htable_size,
1071                                             &nf_conntrack_vmalloc);
1072         if (!nf_conntrack_hash) {
1073                 printk(KERN_ERR "Unable to create nf_conntrack_hash\n");
1074                 goto err_out;
1075         }
1076
1077         nf_conntrack_max = max_factor * nf_conntrack_htable_size;
1078
1079         printk("nf_conntrack version %s (%u buckets, %d max)\n",
1080                NF_CONNTRACK_VERSION, nf_conntrack_htable_size,
1081                nf_conntrack_max);
1082
1083         nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
1084                                                 sizeof(struct nf_conn),
1085                                                 0, 0, NULL, NULL);
1086         if (!nf_conntrack_cachep) {
1087                 printk(KERN_ERR "Unable to create nf_conn slab cache\n");
1088                 goto err_free_hash;
1089         }
1090
1091         nf_conntrack_expect_cachep = kmem_cache_create("nf_conntrack_expect",
1092                                         sizeof(struct nf_conntrack_expect),
1093                                         0, 0, NULL, NULL);
1094         if (!nf_conntrack_expect_cachep) {
1095                 printk(KERN_ERR "Unable to create nf_expect slab cache\n");
1096                 goto err_free_conntrack_slab;
1097         }
1098
1099         ret = nf_conntrack_proto_init();
1100         if (ret < 0)
1101                 goto out_free_expect_slab;
1102
1103         ret = nf_conntrack_helper_init();
1104         if (ret < 0)
1105                 goto out_fini_proto;
1106
1107         /* For use by REJECT target */
1108         rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach);
1109         rcu_assign_pointer(nf_ct_destroy, destroy_conntrack);
1110
1111         /* Set up fake conntrack:
1112             - to never be deleted, not in any hashes */
1113         atomic_set(&nf_conntrack_untracked.ct_general.use, 1);
1114         /*  - and look it like as a confirmed connection */
1115         set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status);
1116
1117         return ret;
1118
1119 out_fini_proto:
1120         nf_conntrack_proto_fini();
1121 out_free_expect_slab:
1122         kmem_cache_destroy(nf_conntrack_expect_cachep);
1123 err_free_conntrack_slab:
1124         kmem_cache_destroy(nf_conntrack_cachep);
1125 err_free_hash:
1126         free_conntrack_hash(nf_conntrack_hash, nf_conntrack_vmalloc,
1127                             nf_conntrack_htable_size);
1128 err_out:
1129         return -ENOMEM;
1130 }