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Arnaldo Carvalho de Melo77d8bf92005-08-09 20:00:51 -07001/*
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/config.h>
Arnaldo Carvalho de Melo2d8c4ce2005-08-09 20:07:13 -070017#include <linux/module.h>
Arnaldo Carvalho de Meloa7f5e7f2005-12-13 23:25:31 -080018#include <linux/random.h>
Arnaldo Carvalho de Melof3f05f72005-08-09 20:08:09 -070019#include <linux/sched.h>
Arnaldo Carvalho de Melo77d8bf92005-08-09 20:00:51 -070020#include <linux/slab.h>
Arnaldo Carvalho de Melof3f05f72005-08-09 20:08:09 -070021#include <linux/wait.h>
Arnaldo Carvalho de Melo77d8bf92005-08-09 20:00:51 -070022
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070023#include <net/inet_connection_sock.h>
Arnaldo Carvalho de Melo77d8bf92005-08-09 20:00:51 -070024#include <net/inet_hashtables.h>
Arnaldo Carvalho de Meloa7f5e7f2005-12-13 23:25:31 -080025#include <net/ip.h>
Arnaldo Carvalho de Melo77d8bf92005-08-09 20:00:51 -070026
27/*
28 * Allocate and initialize a new local port bind bucket.
29 * The bindhash mutex for snum's hash chain must be held here.
30 */
31struct inet_bind_bucket *inet_bind_bucket_create(kmem_cache_t *cachep,
32 struct inet_bind_hashbucket *head,
33 const unsigned short snum)
34{
35 struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, SLAB_ATOMIC);
36
37 if (tb != NULL) {
38 tb->port = snum;
39 tb->fastreuse = 0;
40 INIT_HLIST_HEAD(&tb->owners);
41 hlist_add_head(&tb->node, &head->chain);
42 }
43 return tb;
44}
45
46EXPORT_SYMBOL(inet_bind_bucket_create);
47
48/*
49 * Caller must hold hashbucket lock for this tb with local BH disabled
50 */
51void inet_bind_bucket_destroy(kmem_cache_t *cachep, struct inet_bind_bucket *tb)
52{
53 if (hlist_empty(&tb->owners)) {
54 __hlist_del(&tb->node);
55 kmem_cache_free(cachep, tb);
56 }
57}
Arnaldo Carvalho de Melo2d8c4ce2005-08-09 20:07:13 -070058
59void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
60 const unsigned short snum)
61{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070062 inet_sk(sk)->num = snum;
Arnaldo Carvalho de Melo2d8c4ce2005-08-09 20:07:13 -070063 sk_add_bind_node(sk, &tb->owners);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070064 inet_csk(sk)->icsk_bind_hash = tb;
Arnaldo Carvalho de Melo2d8c4ce2005-08-09 20:07:13 -070065}
66
67EXPORT_SYMBOL(inet_bind_hash);
68
69/*
70 * Get rid of any references to a local port held by the given sock.
71 */
72static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
73{
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070074 const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size);
Arnaldo Carvalho de Melo2d8c4ce2005-08-09 20:07:13 -070075 struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
76 struct inet_bind_bucket *tb;
77
78 spin_lock(&head->lock);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070079 tb = inet_csk(sk)->icsk_bind_hash;
Arnaldo Carvalho de Melo2d8c4ce2005-08-09 20:07:13 -070080 __sk_del_bind_node(sk);
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -070081 inet_csk(sk)->icsk_bind_hash = NULL;
82 inet_sk(sk)->num = 0;
Arnaldo Carvalho de Melo2d8c4ce2005-08-09 20:07:13 -070083 inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
84 spin_unlock(&head->lock);
85}
86
87void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
88{
89 local_bh_disable();
90 __inet_put_port(hashinfo, sk);
91 local_bh_enable();
92}
93
94EXPORT_SYMBOL(inet_put_port);
Arnaldo Carvalho de Melof3f05f72005-08-09 20:08:09 -070095
96/*
97 * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
98 * Look, when several writers sleep and reader wakes them up, all but one
99 * immediately hit write lock and grab all the cpus. Exclusive sleep solves
100 * this, _but_ remember, it adds useless work on UP machines (wake up each
101 * exclusive lock release). It should be ifdefed really.
102 */
103void inet_listen_wlock(struct inet_hashinfo *hashinfo)
104{
105 write_lock(&hashinfo->lhash_lock);
106
107 if (atomic_read(&hashinfo->lhash_users)) {
108 DEFINE_WAIT(wait);
109
110 for (;;) {
111 prepare_to_wait_exclusive(&hashinfo->lhash_wait,
112 &wait, TASK_UNINTERRUPTIBLE);
113 if (!atomic_read(&hashinfo->lhash_users))
114 break;
115 write_unlock_bh(&hashinfo->lhash_lock);
116 schedule();
117 write_lock_bh(&hashinfo->lhash_lock);
118 }
119
120 finish_wait(&hashinfo->lhash_wait, &wait);
121 }
122}
123
124EXPORT_SYMBOL(inet_listen_wlock);
Arnaldo Carvalho de Melo33b62232005-08-09 20:09:06 -0700125
126/*
127 * Don't inline this cruft. Here are some nice properties to exploit here. The
128 * BSD API does not allow a listening sock to specify the remote port nor the
129 * remote address for the connection. So always assume those are both
130 * wildcarded during the search since they can never be otherwise.
131 */
132struct sock *__inet_lookup_listener(const struct hlist_head *head, const u32 daddr,
133 const unsigned short hnum, 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 (inet->num == hnum && !ipv6_only_sock(sk)) {
143 const __u32 rcv_saddr = inet->rcv_saddr;
144 int score = sk->sk_family == PF_INET ? 1 : 0;
145
146 if (rcv_saddr) {
147 if (rcv_saddr != daddr)
148 continue;
149 score += 2;
150 }
151 if (sk->sk_bound_dev_if) {
152 if (sk->sk_bound_dev_if != dif)
153 continue;
154 score += 2;
155 }
156 if (score == 5)
157 return sk;
158 if (score > hiscore) {
159 hiscore = score;
160 result = sk;
161 }
162 }
163 }
164 return result;
165}
Arnaldo Carvalho de Meloe48c4142005-08-09 20:09:46 -0700166
167EXPORT_SYMBOL_GPL(__inet_lookup_listener);
Arnaldo Carvalho de Meloa7f5e7f2005-12-13 23:25:31 -0800168
169/* called with local bh disabled */
170static int __inet_check_established(struct inet_timewait_death_row *death_row,
171 struct sock *sk, __u16 lport,
172 struct inet_timewait_sock **twp)
173{
174 struct inet_hashinfo *hinfo = death_row->hashinfo;
175 struct inet_sock *inet = inet_sk(sk);
176 u32 daddr = inet->rcv_saddr;
177 u32 saddr = inet->daddr;
178 int dif = sk->sk_bound_dev_if;
179 INET_ADDR_COOKIE(acookie, saddr, daddr)
180 const __u32 ports = INET_COMBINED_PORTS(inet->dport, lport);
181 unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);
182 struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
183 struct sock *sk2;
184 const struct hlist_node *node;
185 struct inet_timewait_sock *tw;
186
187 prefetch(head->chain.first);
188 write_lock(&head->lock);
189
190 /* Check TIME-WAIT sockets first. */
191 sk_for_each(sk2, node, &(head + hinfo->ehash_size)->chain) {
192 tw = inet_twsk(sk2);
193
194 if (INET_TW_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) {
195 if (twsk_unique(sk, sk2, twp))
196 goto unique;
197 else
198 goto not_unique;
199 }
200 }
201 tw = NULL;
202
203 /* And established part... */
204 sk_for_each(sk2, node, &head->chain) {
205 if (INET_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif))
206 goto not_unique;
207 }
208
209unique:
210 /* Must record num and sport now. Otherwise we will see
211 * in hash table socket with a funny identity. */
212 inet->num = lport;
213 inet->sport = htons(lport);
214 sk->sk_hash = hash;
215 BUG_TRAP(sk_unhashed(sk));
216 __sk_add_node(sk, &head->chain);
217 sock_prot_inc_use(sk->sk_prot);
218 write_unlock(&head->lock);
219
220 if (twp) {
221 *twp = tw;
222 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
223 } else if (tw) {
224 /* Silly. Should hash-dance instead... */
225 inet_twsk_deschedule(tw, death_row);
226 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
227
228 inet_twsk_put(tw);
229 }
230
231 return 0;
232
233not_unique:
234 write_unlock(&head->lock);
235 return -EADDRNOTAVAIL;
236}
237
238static inline u32 inet_sk_port_offset(const struct sock *sk)
239{
240 const struct inet_sock *inet = inet_sk(sk);
241 return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,
242 inet->dport);
243}
244
245/*
246 * Bind a port for a connect operation and hash it.
247 */
248int inet_hash_connect(struct inet_timewait_death_row *death_row,
249 struct sock *sk)
250{
251 struct inet_hashinfo *hinfo = death_row->hashinfo;
252 const unsigned short snum = inet_sk(sk)->num;
253 struct inet_bind_hashbucket *head;
254 struct inet_bind_bucket *tb;
255 int ret;
256
257 if (!snum) {
258 int low = sysctl_local_port_range[0];
259 int high = sysctl_local_port_range[1];
260 int range = high - low;
261 int i;
262 int port;
263 static u32 hint;
264 u32 offset = hint + inet_sk_port_offset(sk);
265 struct hlist_node *node;
266 struct inet_timewait_sock *tw = NULL;
267
268 local_bh_disable();
269 for (i = 1; i <= range; i++) {
270 port = low + (i + offset) % range;
271 head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
272 spin_lock(&head->lock);
273
274 /* Does not bother with rcv_saddr checks,
275 * because the established check is already
276 * unique enough.
277 */
278 inet_bind_bucket_for_each(tb, node, &head->chain) {
279 if (tb->port == port) {
280 BUG_TRAP(!hlist_empty(&tb->owners));
281 if (tb->fastreuse >= 0)
282 goto next_port;
283 if (!__inet_check_established(death_row,
284 sk, port,
285 &tw))
286 goto ok;
287 goto next_port;
288 }
289 }
290
291 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, head, port);
292 if (!tb) {
293 spin_unlock(&head->lock);
294 break;
295 }
296 tb->fastreuse = -1;
297 goto ok;
298
299 next_port:
300 spin_unlock(&head->lock);
301 }
302 local_bh_enable();
303
304 return -EADDRNOTAVAIL;
305
306ok:
307 hint += i;
308
309 /* Head lock still held and bh's disabled */
310 inet_bind_hash(sk, tb, port);
311 if (sk_unhashed(sk)) {
312 inet_sk(sk)->sport = htons(port);
313 __inet_hash(hinfo, sk, 0);
314 }
315 spin_unlock(&head->lock);
316
317 if (tw) {
Alexey Dobriyan53b35312006-03-24 03:16:13 -0800318 inet_twsk_deschedule(tw, death_row);
Arnaldo Carvalho de Meloa7f5e7f2005-12-13 23:25:31 -0800319 inet_twsk_put(tw);
320 }
321
322 ret = 0;
323 goto out;
324 }
325
326 head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)];
327 tb = inet_csk(sk)->icsk_bind_hash;
328 spin_lock_bh(&head->lock);
329 if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
330 __inet_hash(hinfo, sk, 0);
331 spin_unlock_bh(&head->lock);
332 return 0;
333 } else {
334 spin_unlock(&head->lock);
335 /* No definite answer... Walk to established hash table */
336 ret = __inet_check_established(death_row, sk, snum, NULL);
337out:
338 local_bh_enable();
339 return ret;
340 }
341}
342
343EXPORT_SYMBOL_GPL(inet_hash_connect);