net/ipv4: EXPORT_SYMBOL cleanups
[linux-3.10.git] / net / ipv4 / inet_hashtables.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              Generic INET transport hashtables
7  *
8  * Authors:     Lotsa people, from code originally in tcp
9  *
10  *      This program is free software; you can redistribute it and/or
11  *      modify it under the terms of the GNU General Public License
12  *      as published by the Free Software Foundation; either version
13  *      2 of the License, or (at your option) any later version.
14  */
15
16 #include <linux/module.h>
17 #include <linux/random.h>
18 #include <linux/sched.h>
19 #include <linux/slab.h>
20 #include <linux/wait.h>
21
22 #include <net/inet_connection_sock.h>
23 #include <net/inet_hashtables.h>
24 #include <net/ip.h>
25
26 /*
27  * Allocate and initialize a new local port bind bucket.
28  * The bindhash mutex for snum's hash chain must be held here.
29  */
30 struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
31                                                  struct net *net,
32                                                  struct inet_bind_hashbucket *head,
33                                                  const unsigned short snum)
34 {
35         struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
36
37         if (tb != NULL) {
38                 write_pnet(&tb->ib_net, hold_net(net));
39                 tb->port      = snum;
40                 tb->fastreuse = 0;
41                 tb->num_owners = 0;
42                 INIT_HLIST_HEAD(&tb->owners);
43                 hlist_add_head(&tb->node, &head->chain);
44         }
45         return tb;
46 }
47
48 /*
49  * Caller must hold hashbucket lock for this tb with local BH disabled
50  */
51 void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
52 {
53         if (hlist_empty(&tb->owners)) {
54                 __hlist_del(&tb->node);
55                 release_net(ib_net(tb));
56                 kmem_cache_free(cachep, tb);
57         }
58 }
59
60 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
61                     const unsigned short snum)
62 {
63         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
64
65         atomic_inc(&hashinfo->bsockets);
66
67         inet_sk(sk)->inet_num = snum;
68         sk_add_bind_node(sk, &tb->owners);
69         tb->num_owners++;
70         inet_csk(sk)->icsk_bind_hash = tb;
71 }
72
73 /*
74  * Get rid of any references to a local port held by the given sock.
75  */
76 static void __inet_put_port(struct sock *sk)
77 {
78         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
79         const int bhash = inet_bhashfn(sock_net(sk), inet_sk(sk)->inet_num,
80                         hashinfo->bhash_size);
81         struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
82         struct inet_bind_bucket *tb;
83
84         atomic_dec(&hashinfo->bsockets);
85
86         spin_lock(&head->lock);
87         tb = inet_csk(sk)->icsk_bind_hash;
88         __sk_del_bind_node(sk);
89         tb->num_owners--;
90         inet_csk(sk)->icsk_bind_hash = NULL;
91         inet_sk(sk)->inet_num = 0;
92         inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
93         spin_unlock(&head->lock);
94 }
95
96 void inet_put_port(struct sock *sk)
97 {
98         local_bh_disable();
99         __inet_put_port(sk);
100         local_bh_enable();
101 }
102 EXPORT_SYMBOL(inet_put_port);
103
104 void __inet_inherit_port(struct sock *sk, struct sock *child)
105 {
106         struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
107         const int bhash = inet_bhashfn(sock_net(sk), inet_sk(child)->inet_num,
108                         table->bhash_size);
109         struct inet_bind_hashbucket *head = &table->bhash[bhash];
110         struct inet_bind_bucket *tb;
111
112         spin_lock(&head->lock);
113         tb = inet_csk(sk)->icsk_bind_hash;
114         sk_add_bind_node(child, &tb->owners);
115         inet_csk(child)->icsk_bind_hash = tb;
116         spin_unlock(&head->lock);
117 }
118 EXPORT_SYMBOL_GPL(__inet_inherit_port);
119
120 static inline int compute_score(struct sock *sk, struct net *net,
121                                 const unsigned short hnum, const __be32 daddr,
122                                 const int dif)
123 {
124         int score = -1;
125         struct inet_sock *inet = inet_sk(sk);
126
127         if (net_eq(sock_net(sk), net) && inet->inet_num == hnum &&
128                         !ipv6_only_sock(sk)) {
129                 __be32 rcv_saddr = inet->inet_rcv_saddr;
130                 score = sk->sk_family == PF_INET ? 1 : 0;
131                 if (rcv_saddr) {
132                         if (rcv_saddr != daddr)
133                                 return -1;
134                         score += 2;
135                 }
136                 if (sk->sk_bound_dev_if) {
137                         if (sk->sk_bound_dev_if != dif)
138                                 return -1;
139                         score += 2;
140                 }
141         }
142         return score;
143 }
144
145 /*
146  * Don't inline this cruft. Here are some nice properties to exploit here. The
147  * BSD API does not allow a listening sock to specify the remote port nor the
148  * remote address for the connection. So always assume those are both
149  * wildcarded during the search since they can never be otherwise.
150  */
151
152
153 struct sock *__inet_lookup_listener(struct net *net,
154                                     struct inet_hashinfo *hashinfo,
155                                     const __be32 daddr, const unsigned short hnum,
156                                     const int dif)
157 {
158         struct sock *sk, *result;
159         struct hlist_nulls_node *node;
160         unsigned int hash = inet_lhashfn(net, hnum);
161         struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
162         int score, hiscore;
163
164         rcu_read_lock();
165 begin:
166         result = NULL;
167         hiscore = -1;
168         sk_nulls_for_each_rcu(sk, node, &ilb->head) {
169                 score = compute_score(sk, net, hnum, daddr, dif);
170                 if (score > hiscore) {
171                         result = sk;
172                         hiscore = score;
173                 }
174         }
175         /*
176          * if the nulls value we got at the end of this lookup is
177          * not the expected one, we must restart lookup.
178          * We probably met an item that was moved to another chain.
179          */
180         if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
181                 goto begin;
182         if (result) {
183                 if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
184                         result = NULL;
185                 else if (unlikely(compute_score(result, net, hnum, daddr,
186                                   dif) < hiscore)) {
187                         sock_put(result);
188                         goto begin;
189                 }
190         }
191         rcu_read_unlock();
192         return result;
193 }
194 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
195
196 struct sock * __inet_lookup_established(struct net *net,
197                                   struct inet_hashinfo *hashinfo,
198                                   const __be32 saddr, const __be16 sport,
199                                   const __be32 daddr, const u16 hnum,
200                                   const int dif)
201 {
202         INET_ADDR_COOKIE(acookie, saddr, daddr)
203         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
204         struct sock *sk;
205         const struct hlist_nulls_node *node;
206         /* Optimize here for direct hit, only listening connections can
207          * have wildcards anyways.
208          */
209         unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
210         unsigned int slot = hash & hashinfo->ehash_mask;
211         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
212
213         rcu_read_lock();
214 begin:
215         sk_nulls_for_each_rcu(sk, node, &head->chain) {
216                 if (INET_MATCH(sk, net, hash, acookie,
217                                         saddr, daddr, ports, dif)) {
218                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
219                                 goto begintw;
220                         if (unlikely(!INET_MATCH(sk, net, hash, acookie,
221                                 saddr, daddr, ports, dif))) {
222                                 sock_put(sk);
223                                 goto begin;
224                         }
225                         goto out;
226                 }
227         }
228         /*
229          * if the nulls value we got at the end of this lookup is
230          * not the expected one, we must restart lookup.
231          * We probably met an item that was moved to another chain.
232          */
233         if (get_nulls_value(node) != slot)
234                 goto begin;
235
236 begintw:
237         /* Must check for a TIME_WAIT'er before going to listener hash. */
238         sk_nulls_for_each_rcu(sk, node, &head->twchain) {
239                 if (INET_TW_MATCH(sk, net, hash, acookie,
240                                         saddr, daddr, ports, dif)) {
241                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
242                                 sk = NULL;
243                                 goto out;
244                         }
245                         if (unlikely(!INET_TW_MATCH(sk, net, hash, acookie,
246                                  saddr, daddr, ports, dif))) {
247                                 sock_put(sk);
248                                 goto begintw;
249                         }
250                         goto out;
251                 }
252         }
253         /*
254          * if the nulls value we got at the end of this lookup is
255          * not the expected one, we must restart lookup.
256          * We probably met an item that was moved to another chain.
257          */
258         if (get_nulls_value(node) != slot)
259                 goto begintw;
260         sk = NULL;
261 out:
262         rcu_read_unlock();
263         return sk;
264 }
265 EXPORT_SYMBOL_GPL(__inet_lookup_established);
266
267 /* called with local bh disabled */
268 static int __inet_check_established(struct inet_timewait_death_row *death_row,
269                                     struct sock *sk, __u16 lport,
270                                     struct inet_timewait_sock **twp)
271 {
272         struct inet_hashinfo *hinfo = death_row->hashinfo;
273         struct inet_sock *inet = inet_sk(sk);
274         __be32 daddr = inet->inet_rcv_saddr;
275         __be32 saddr = inet->inet_daddr;
276         int dif = sk->sk_bound_dev_if;
277         INET_ADDR_COOKIE(acookie, saddr, daddr)
278         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
279         struct net *net = sock_net(sk);
280         unsigned int hash = inet_ehashfn(net, daddr, lport,
281                                          saddr, inet->inet_dport);
282         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
283         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
284         struct sock *sk2;
285         const struct hlist_nulls_node *node;
286         struct inet_timewait_sock *tw;
287         int twrefcnt = 0;
288
289         spin_lock(lock);
290
291         /* Check TIME-WAIT sockets first. */
292         sk_nulls_for_each(sk2, node, &head->twchain) {
293                 tw = inet_twsk(sk2);
294
295                 if (INET_TW_MATCH(sk2, net, hash, acookie,
296                                         saddr, daddr, ports, dif)) {
297                         if (twsk_unique(sk, sk2, twp))
298                                 goto unique;
299                         else
300                                 goto not_unique;
301                 }
302         }
303         tw = NULL;
304
305         /* And established part... */
306         sk_nulls_for_each(sk2, node, &head->chain) {
307                 if (INET_MATCH(sk2, net, hash, acookie,
308                                         saddr, daddr, ports, dif))
309                         goto not_unique;
310         }
311
312 unique:
313         /* Must record num and sport now. Otherwise we will see
314          * in hash table socket with a funny identity. */
315         inet->inet_num = lport;
316         inet->inet_sport = htons(lport);
317         sk->sk_hash = hash;
318         WARN_ON(!sk_unhashed(sk));
319         __sk_nulls_add_node_rcu(sk, &head->chain);
320         if (tw) {
321                 twrefcnt = inet_twsk_unhash(tw);
322                 NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
323         }
324         spin_unlock(lock);
325         if (twrefcnt)
326                 inet_twsk_put(tw);
327         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
328
329         if (twp) {
330                 *twp = tw;
331         } else if (tw) {
332                 /* Silly. Should hash-dance instead... */
333                 inet_twsk_deschedule(tw, death_row);
334
335                 inet_twsk_put(tw);
336         }
337         return 0;
338
339 not_unique:
340         spin_unlock(lock);
341         return -EADDRNOTAVAIL;
342 }
343
344 static inline u32 inet_sk_port_offset(const struct sock *sk)
345 {
346         const struct inet_sock *inet = inet_sk(sk);
347         return secure_ipv4_port_ephemeral(inet->inet_rcv_saddr,
348                                           inet->inet_daddr,
349                                           inet->inet_dport);
350 }
351
352 int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw)
353 {
354         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
355         struct hlist_nulls_head *list;
356         spinlock_t *lock;
357         struct inet_ehash_bucket *head;
358         int twrefcnt = 0;
359
360         WARN_ON(!sk_unhashed(sk));
361
362         sk->sk_hash = inet_sk_ehashfn(sk);
363         head = inet_ehash_bucket(hashinfo, sk->sk_hash);
364         list = &head->chain;
365         lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
366
367         spin_lock(lock);
368         __sk_nulls_add_node_rcu(sk, list);
369         if (tw) {
370                 WARN_ON(sk->sk_hash != tw->tw_hash);
371                 twrefcnt = inet_twsk_unhash(tw);
372         }
373         spin_unlock(lock);
374         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
375         return twrefcnt;
376 }
377 EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
378
379 static void __inet_hash(struct sock *sk)
380 {
381         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
382         struct inet_listen_hashbucket *ilb;
383
384         if (sk->sk_state != TCP_LISTEN) {
385                 __inet_hash_nolisten(sk, NULL);
386                 return;
387         }
388
389         WARN_ON(!sk_unhashed(sk));
390         ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
391
392         spin_lock(&ilb->lock);
393         __sk_nulls_add_node_rcu(sk, &ilb->head);
394         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
395         spin_unlock(&ilb->lock);
396 }
397
398 void inet_hash(struct sock *sk)
399 {
400         if (sk->sk_state != TCP_CLOSE) {
401                 local_bh_disable();
402                 __inet_hash(sk);
403                 local_bh_enable();
404         }
405 }
406 EXPORT_SYMBOL_GPL(inet_hash);
407
408 void inet_unhash(struct sock *sk)
409 {
410         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
411         spinlock_t *lock;
412         int done;
413
414         if (sk_unhashed(sk))
415                 return;
416
417         if (sk->sk_state == TCP_LISTEN)
418                 lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
419         else
420                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
421
422         spin_lock_bh(lock);
423         done =__sk_nulls_del_node_init_rcu(sk);
424         if (done)
425                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
426         spin_unlock_bh(lock);
427 }
428 EXPORT_SYMBOL_GPL(inet_unhash);
429
430 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
431                 struct sock *sk, u32 port_offset,
432                 int (*check_established)(struct inet_timewait_death_row *,
433                         struct sock *, __u16, struct inet_timewait_sock **),
434                 int (*hash)(struct sock *sk, struct inet_timewait_sock *twp))
435 {
436         struct inet_hashinfo *hinfo = death_row->hashinfo;
437         const unsigned short snum = inet_sk(sk)->inet_num;
438         struct inet_bind_hashbucket *head;
439         struct inet_bind_bucket *tb;
440         int ret;
441         struct net *net = sock_net(sk);
442         int twrefcnt = 1;
443
444         if (!snum) {
445                 int i, remaining, low, high, port;
446                 static u32 hint;
447                 u32 offset = hint + port_offset;
448                 struct hlist_node *node;
449                 struct inet_timewait_sock *tw = NULL;
450
451                 inet_get_local_port_range(&low, &high);
452                 remaining = (high - low) + 1;
453
454                 local_bh_disable();
455                 for (i = 1; i <= remaining; i++) {
456                         port = low + (i + offset) % remaining;
457                         if (inet_is_reserved_local_port(port))
458                                 continue;
459                         head = &hinfo->bhash[inet_bhashfn(net, port,
460                                         hinfo->bhash_size)];
461                         spin_lock(&head->lock);
462
463                         /* Does not bother with rcv_saddr checks,
464                          * because the established check is already
465                          * unique enough.
466                          */
467                         inet_bind_bucket_for_each(tb, node, &head->chain) {
468                                 if (net_eq(ib_net(tb), net) &&
469                                     tb->port == port) {
470                                         if (tb->fastreuse >= 0)
471                                                 goto next_port;
472                                         WARN_ON(hlist_empty(&tb->owners));
473                                         if (!check_established(death_row, sk,
474                                                                 port, &tw))
475                                                 goto ok;
476                                         goto next_port;
477                                 }
478                         }
479
480                         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
481                                         net, head, port);
482                         if (!tb) {
483                                 spin_unlock(&head->lock);
484                                 break;
485                         }
486                         tb->fastreuse = -1;
487                         goto ok;
488
489                 next_port:
490                         spin_unlock(&head->lock);
491                 }
492                 local_bh_enable();
493
494                 return -EADDRNOTAVAIL;
495
496 ok:
497                 hint += i;
498
499                 /* Head lock still held and bh's disabled */
500                 inet_bind_hash(sk, tb, port);
501                 if (sk_unhashed(sk)) {
502                         inet_sk(sk)->inet_sport = htons(port);
503                         twrefcnt += hash(sk, tw);
504                 }
505                 if (tw)
506                         twrefcnt += inet_twsk_bind_unhash(tw, hinfo);
507                 spin_unlock(&head->lock);
508
509                 if (tw) {
510                         inet_twsk_deschedule(tw, death_row);
511                         while (twrefcnt) {
512                                 twrefcnt--;
513                                 inet_twsk_put(tw);
514                         }
515                 }
516
517                 ret = 0;
518                 goto out;
519         }
520
521         head = &hinfo->bhash[inet_bhashfn(net, snum, hinfo->bhash_size)];
522         tb  = inet_csk(sk)->icsk_bind_hash;
523         spin_lock_bh(&head->lock);
524         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
525                 hash(sk, NULL);
526                 spin_unlock_bh(&head->lock);
527                 return 0;
528         } else {
529                 spin_unlock(&head->lock);
530                 /* No definite answer... Walk to established hash table */
531                 ret = check_established(death_row, sk, snum, NULL);
532 out:
533                 local_bh_enable();
534                 return ret;
535         }
536 }
537
538 /*
539  * Bind a port for a connect operation and hash it.
540  */
541 int inet_hash_connect(struct inet_timewait_death_row *death_row,
542                       struct sock *sk)
543 {
544         return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
545                         __inet_check_established, __inet_hash_nolisten);
546 }
547 EXPORT_SYMBOL_GPL(inet_hash_connect);
548
549 void inet_hashinfo_init(struct inet_hashinfo *h)
550 {
551         int i;
552
553         atomic_set(&h->bsockets, 0);
554         for (i = 0; i < INET_LHTABLE_SIZE; i++) {
555                 spin_lock_init(&h->listening_hash[i].lock);
556                 INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].head,
557                                       i + LISTENING_NULLS_BASE);
558                 }
559 }
560 EXPORT_SYMBOL_GPL(inet_hashinfo_init);