[NET] NETNS: Omit sock->sk_net without CONFIG_NET_NS.
[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                 tb->ib_net       = net;
39                 tb->port      = snum;
40                 tb->fastreuse = 0;
41                 INIT_HLIST_HEAD(&tb->owners);
42                 hlist_add_head(&tb->node, &head->chain);
43         }
44         return tb;
45 }
46
47 /*
48  * Caller must hold hashbucket lock for this tb with local BH disabled
49  */
50 void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
51 {
52         if (hlist_empty(&tb->owners)) {
53                 __hlist_del(&tb->node);
54                 kmem_cache_free(cachep, tb);
55         }
56 }
57
58 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
59                     const unsigned short snum)
60 {
61         inet_sk(sk)->num = snum;
62         sk_add_bind_node(sk, &tb->owners);
63         inet_csk(sk)->icsk_bind_hash = tb;
64 }
65
66 /*
67  * Get rid of any references to a local port held by the given sock.
68  */
69 static void __inet_put_port(struct sock *sk)
70 {
71         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
72         const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size);
73         struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
74         struct inet_bind_bucket *tb;
75
76         spin_lock(&head->lock);
77         tb = inet_csk(sk)->icsk_bind_hash;
78         __sk_del_bind_node(sk);
79         inet_csk(sk)->icsk_bind_hash = NULL;
80         inet_sk(sk)->num = 0;
81         inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
82         spin_unlock(&head->lock);
83 }
84
85 void inet_put_port(struct sock *sk)
86 {
87         local_bh_disable();
88         __inet_put_port(sk);
89         local_bh_enable();
90 }
91
92 EXPORT_SYMBOL(inet_put_port);
93
94 /*
95  * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
96  * Look, when several writers sleep and reader wakes them up, all but one
97  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
98  * this, _but_ remember, it adds useless work on UP machines (wake up each
99  * exclusive lock release). It should be ifdefed really.
100  */
101 void inet_listen_wlock(struct inet_hashinfo *hashinfo)
102         __acquires(hashinfo->lhash_lock)
103 {
104         write_lock(&hashinfo->lhash_lock);
105
106         if (atomic_read(&hashinfo->lhash_users)) {
107                 DEFINE_WAIT(wait);
108
109                 for (;;) {
110                         prepare_to_wait_exclusive(&hashinfo->lhash_wait,
111                                                   &wait, TASK_UNINTERRUPTIBLE);
112                         if (!atomic_read(&hashinfo->lhash_users))
113                                 break;
114                         write_unlock_bh(&hashinfo->lhash_lock);
115                         schedule();
116                         write_lock_bh(&hashinfo->lhash_lock);
117                 }
118
119                 finish_wait(&hashinfo->lhash_wait, &wait);
120         }
121 }
122
123 /*
124  * Don't inline this cruft. Here are some nice properties to exploit here. The
125  * BSD API does not allow a listening sock to specify the remote port nor the
126  * remote address for the connection. So always assume those are both
127  * wildcarded during the search since they can never be otherwise.
128  */
129 static struct sock *inet_lookup_listener_slow(struct net *net,
130                                               const struct hlist_head *head,
131                                               const __be32 daddr,
132                                               const unsigned short hnum,
133                                               const int dif)
134 {
135         struct sock *result = NULL, *sk;
136         const struct hlist_node *node;
137         int hiscore = -1;
138
139         sk_for_each(sk, node, head) {
140                 const struct inet_sock *inet = inet_sk(sk);
141
142                 if (sock_net(sk) == net && inet->num == hnum &&
143                                 !ipv6_only_sock(sk)) {
144                         const __be32 rcv_saddr = inet->rcv_saddr;
145                         int score = sk->sk_family == PF_INET ? 1 : 0;
146
147                         if (rcv_saddr) {
148                                 if (rcv_saddr != daddr)
149                                         continue;
150                                 score += 2;
151                         }
152                         if (sk->sk_bound_dev_if) {
153                                 if (sk->sk_bound_dev_if != dif)
154                                         continue;
155                                 score += 2;
156                         }
157                         if (score == 5)
158                                 return sk;
159                         if (score > hiscore) {
160                                 hiscore = score;
161                                 result  = sk;
162                         }
163                 }
164         }
165         return result;
166 }
167
168 /* Optimize the common listener case. */
169 struct sock *__inet_lookup_listener(struct net *net,
170                                     struct inet_hashinfo *hashinfo,
171                                     const __be32 daddr, const unsigned short hnum,
172                                     const int dif)
173 {
174         struct sock *sk = NULL;
175         const struct hlist_head *head;
176
177         read_lock(&hashinfo->lhash_lock);
178         head = &hashinfo->listening_hash[inet_lhashfn(hnum)];
179         if (!hlist_empty(head)) {
180                 const struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
181
182                 if (inet->num == hnum && !sk->sk_node.next &&
183                     (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
184                     (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
185                     !sk->sk_bound_dev_if && sock_net(sk) == net)
186                         goto sherry_cache;
187                 sk = inet_lookup_listener_slow(net, head, daddr, hnum, dif);
188         }
189         if (sk) {
190 sherry_cache:
191                 sock_hold(sk);
192         }
193         read_unlock(&hashinfo->lhash_lock);
194         return sk;
195 }
196 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
197
198 struct sock * __inet_lookup_established(struct net *net,
199                                   struct inet_hashinfo *hashinfo,
200                                   const __be32 saddr, const __be16 sport,
201                                   const __be32 daddr, const u16 hnum,
202                                   const int dif)
203 {
204         INET_ADDR_COOKIE(acookie, saddr, daddr)
205         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
206         struct sock *sk;
207         const struct hlist_node *node;
208         /* Optimize here for direct hit, only listening connections can
209          * have wildcards anyways.
210          */
211         unsigned int hash = inet_ehashfn(daddr, hnum, saddr, sport);
212         struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash);
213         rwlock_t *lock = inet_ehash_lockp(hashinfo, hash);
214
215         prefetch(head->chain.first);
216         read_lock(lock);
217         sk_for_each(sk, node, &head->chain) {
218                 if (INET_MATCH(sk, net, hash, acookie,
219                                         saddr, daddr, ports, dif))
220                         goto hit; /* You sunk my battleship! */
221         }
222
223         /* Must check for a TIME_WAIT'er before going to listener hash. */
224         sk_for_each(sk, node, &head->twchain) {
225                 if (INET_TW_MATCH(sk, net, hash, acookie,
226                                         saddr, daddr, ports, dif))
227                         goto hit;
228         }
229         sk = NULL;
230 out:
231         read_unlock(lock);
232         return sk;
233 hit:
234         sock_hold(sk);
235         goto out;
236 }
237 EXPORT_SYMBOL_GPL(__inet_lookup_established);
238
239 /* called with local bh disabled */
240 static int __inet_check_established(struct inet_timewait_death_row *death_row,
241                                     struct sock *sk, __u16 lport,
242                                     struct inet_timewait_sock **twp)
243 {
244         struct inet_hashinfo *hinfo = death_row->hashinfo;
245         struct inet_sock *inet = inet_sk(sk);
246         __be32 daddr = inet->rcv_saddr;
247         __be32 saddr = inet->daddr;
248         int dif = sk->sk_bound_dev_if;
249         INET_ADDR_COOKIE(acookie, saddr, daddr)
250         const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport);
251         unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);
252         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
253         rwlock_t *lock = inet_ehash_lockp(hinfo, hash);
254         struct sock *sk2;
255         const struct hlist_node *node;
256         struct inet_timewait_sock *tw;
257         struct net *net = sock_net(sk);
258
259         prefetch(head->chain.first);
260         write_lock(lock);
261
262         /* Check TIME-WAIT sockets first. */
263         sk_for_each(sk2, node, &head->twchain) {
264                 tw = inet_twsk(sk2);
265
266                 if (INET_TW_MATCH(sk2, net, hash, acookie,
267                                         saddr, daddr, ports, dif)) {
268                         if (twsk_unique(sk, sk2, twp))
269                                 goto unique;
270                         else
271                                 goto not_unique;
272                 }
273         }
274         tw = NULL;
275
276         /* And established part... */
277         sk_for_each(sk2, node, &head->chain) {
278                 if (INET_MATCH(sk2, net, hash, acookie,
279                                         saddr, daddr, ports, dif))
280                         goto not_unique;
281         }
282
283 unique:
284         /* Must record num and sport now. Otherwise we will see
285          * in hash table socket with a funny identity. */
286         inet->num = lport;
287         inet->sport = htons(lport);
288         sk->sk_hash = hash;
289         BUG_TRAP(sk_unhashed(sk));
290         __sk_add_node(sk, &head->chain);
291         sock_prot_inuse_add(sk->sk_prot, 1);
292         write_unlock(lock);
293
294         if (twp) {
295                 *twp = tw;
296                 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
297         } else if (tw) {
298                 /* Silly. Should hash-dance instead... */
299                 inet_twsk_deschedule(tw, death_row);
300                 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
301
302                 inet_twsk_put(tw);
303         }
304
305         return 0;
306
307 not_unique:
308         write_unlock(lock);
309         return -EADDRNOTAVAIL;
310 }
311
312 static inline u32 inet_sk_port_offset(const struct sock *sk)
313 {
314         const struct inet_sock *inet = inet_sk(sk);
315         return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,
316                                           inet->dport);
317 }
318
319 void __inet_hash_nolisten(struct sock *sk)
320 {
321         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
322         struct hlist_head *list;
323         rwlock_t *lock;
324         struct inet_ehash_bucket *head;
325
326         BUG_TRAP(sk_unhashed(sk));
327
328         sk->sk_hash = inet_sk_ehashfn(sk);
329         head = inet_ehash_bucket(hashinfo, sk->sk_hash);
330         list = &head->chain;
331         lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
332
333         write_lock(lock);
334         __sk_add_node(sk, list);
335         sock_prot_inuse_add(sk->sk_prot, 1);
336         write_unlock(lock);
337 }
338 EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
339
340 static void __inet_hash(struct sock *sk)
341 {
342         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
343         struct hlist_head *list;
344         rwlock_t *lock;
345
346         if (sk->sk_state != TCP_LISTEN) {
347                 __inet_hash_nolisten(sk);
348                 return;
349         }
350
351         BUG_TRAP(sk_unhashed(sk));
352         list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
353         lock = &hashinfo->lhash_lock;
354
355         inet_listen_wlock(hashinfo);
356         __sk_add_node(sk, list);
357         sock_prot_inuse_add(sk->sk_prot, 1);
358         write_unlock(lock);
359         wake_up(&hashinfo->lhash_wait);
360 }
361
362 void inet_hash(struct sock *sk)
363 {
364         if (sk->sk_state != TCP_CLOSE) {
365                 local_bh_disable();
366                 __inet_hash(sk);
367                 local_bh_enable();
368         }
369 }
370 EXPORT_SYMBOL_GPL(inet_hash);
371
372 void inet_unhash(struct sock *sk)
373 {
374         rwlock_t *lock;
375         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
376
377         if (sk_unhashed(sk))
378                 goto out;
379
380         if (sk->sk_state == TCP_LISTEN) {
381                 local_bh_disable();
382                 inet_listen_wlock(hashinfo);
383                 lock = &hashinfo->lhash_lock;
384         } else {
385                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
386                 write_lock_bh(lock);
387         }
388
389         if (__sk_del_node_init(sk))
390                 sock_prot_inuse_add(sk->sk_prot, -1);
391         write_unlock_bh(lock);
392 out:
393         if (sk->sk_state == TCP_LISTEN)
394                 wake_up(&hashinfo->lhash_wait);
395 }
396 EXPORT_SYMBOL_GPL(inet_unhash);
397
398 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
399                 struct sock *sk, u32 port_offset,
400                 int (*check_established)(struct inet_timewait_death_row *,
401                         struct sock *, __u16, struct inet_timewait_sock **),
402                 void (*hash)(struct sock *sk))
403 {
404         struct inet_hashinfo *hinfo = death_row->hashinfo;
405         const unsigned short snum = inet_sk(sk)->num;
406         struct inet_bind_hashbucket *head;
407         struct inet_bind_bucket *tb;
408         int ret;
409         struct net *net = sock_net(sk);
410
411         if (!snum) {
412                 int i, remaining, low, high, port;
413                 static u32 hint;
414                 u32 offset = hint + port_offset;
415                 struct hlist_node *node;
416                 struct inet_timewait_sock *tw = NULL;
417
418                 inet_get_local_port_range(&low, &high);
419                 remaining = (high - low) + 1;
420
421                 local_bh_disable();
422                 for (i = 1; i <= remaining; i++) {
423                         port = low + (i + offset) % remaining;
424                         head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
425                         spin_lock(&head->lock);
426
427                         /* Does not bother with rcv_saddr checks,
428                          * because the established check is already
429                          * unique enough.
430                          */
431                         inet_bind_bucket_for_each(tb, node, &head->chain) {
432                                 if (tb->ib_net == net && tb->port == port) {
433                                         BUG_TRAP(!hlist_empty(&tb->owners));
434                                         if (tb->fastreuse >= 0)
435                                                 goto next_port;
436                                         if (!check_established(death_row, sk,
437                                                                 port, &tw))
438                                                 goto ok;
439                                         goto next_port;
440                                 }
441                         }
442
443                         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
444                                         net, head, port);
445                         if (!tb) {
446                                 spin_unlock(&head->lock);
447                                 break;
448                         }
449                         tb->fastreuse = -1;
450                         goto ok;
451
452                 next_port:
453                         spin_unlock(&head->lock);
454                 }
455                 local_bh_enable();
456
457                 return -EADDRNOTAVAIL;
458
459 ok:
460                 hint += i;
461
462                 /* Head lock still held and bh's disabled */
463                 inet_bind_hash(sk, tb, port);
464                 if (sk_unhashed(sk)) {
465                         inet_sk(sk)->sport = htons(port);
466                         hash(sk);
467                 }
468                 spin_unlock(&head->lock);
469
470                 if (tw) {
471                         inet_twsk_deschedule(tw, death_row);
472                         inet_twsk_put(tw);
473                 }
474
475                 ret = 0;
476                 goto out;
477         }
478
479         head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)];
480         tb  = inet_csk(sk)->icsk_bind_hash;
481         spin_lock_bh(&head->lock);
482         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
483                 hash(sk);
484                 spin_unlock_bh(&head->lock);
485                 return 0;
486         } else {
487                 spin_unlock(&head->lock);
488                 /* No definite answer... Walk to established hash table */
489                 ret = check_established(death_row, sk, snum, NULL);
490 out:
491                 local_bh_enable();
492                 return ret;
493         }
494 }
495
496 /*
497  * Bind a port for a connect operation and hash it.
498  */
499 int inet_hash_connect(struct inet_timewait_death_row *death_row,
500                       struct sock *sk)
501 {
502         return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
503                         __inet_check_established, __inet_hash_nolisten);
504 }
505
506 EXPORT_SYMBOL_GPL(inet_hash_connect);