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