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.
6 * Generic INET transport hashtables
8 * Authors: Lotsa people, from code originally in tcp
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.
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>
22 #include <net/inet_connection_sock.h>
23 #include <net/inet_hashtables.h>
27 * Allocate and initialize a new local port bind bucket.
28 * The bindhash mutex for snum's hash chain must be held here.
30 struct inet_bind_bucket *inet_bind_bucket_create(kmem_cache_t *cachep,
31 struct inet_bind_hashbucket *head,
32 const unsigned short snum)
34 struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, SLAB_ATOMIC);
39 INIT_HLIST_HEAD(&tb->owners);
40 hlist_add_head(&tb->node, &head->chain);
46 * Caller must hold hashbucket lock for this tb with local BH disabled
48 void inet_bind_bucket_destroy(kmem_cache_t *cachep, struct inet_bind_bucket *tb)
50 if (hlist_empty(&tb->owners)) {
51 __hlist_del(&tb->node);
52 kmem_cache_free(cachep, tb);
56 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
57 const unsigned short snum)
59 inet_sk(sk)->num = snum;
60 sk_add_bind_node(sk, &tb->owners);
61 inet_csk(sk)->icsk_bind_hash = tb;
65 * Get rid of any references to a local port held by the given sock.
67 static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
69 const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size);
70 struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
71 struct inet_bind_bucket *tb;
73 spin_lock(&head->lock);
74 tb = inet_csk(sk)->icsk_bind_hash;
75 __sk_del_bind_node(sk);
76 inet_csk(sk)->icsk_bind_hash = NULL;
78 inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
79 spin_unlock(&head->lock);
82 void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
85 __inet_put_port(hashinfo, sk);
89 EXPORT_SYMBOL(inet_put_port);
92 * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
93 * Look, when several writers sleep and reader wakes them up, all but one
94 * immediately hit write lock and grab all the cpus. Exclusive sleep solves
95 * this, _but_ remember, it adds useless work on UP machines (wake up each
96 * exclusive lock release). It should be ifdefed really.
98 void inet_listen_wlock(struct inet_hashinfo *hashinfo)
100 write_lock(&hashinfo->lhash_lock);
102 if (atomic_read(&hashinfo->lhash_users)) {
106 prepare_to_wait_exclusive(&hashinfo->lhash_wait,
107 &wait, TASK_UNINTERRUPTIBLE);
108 if (!atomic_read(&hashinfo->lhash_users))
110 write_unlock_bh(&hashinfo->lhash_lock);
112 write_lock_bh(&hashinfo->lhash_lock);
115 finish_wait(&hashinfo->lhash_wait, &wait);
119 EXPORT_SYMBOL(inet_listen_wlock);
122 * Don't inline this cruft. Here are some nice properties to exploit here. The
123 * BSD API does not allow a listening sock to specify the remote port nor the
124 * remote address for the connection. So always assume those are both
125 * wildcarded during the search since they can never be otherwise.
127 struct sock *__inet_lookup_listener(const struct hlist_head *head, const u32 daddr,
128 const unsigned short hnum, const int dif)
130 struct sock *result = NULL, *sk;
131 const struct hlist_node *node;
134 sk_for_each(sk, node, head) {
135 const struct inet_sock *inet = inet_sk(sk);
137 if (inet->num == hnum && !ipv6_only_sock(sk)) {
138 const __u32 rcv_saddr = inet->rcv_saddr;
139 int score = sk->sk_family == PF_INET ? 1 : 0;
141 if (inet_addr_match(sk->sk_nx_info, daddr, rcv_saddr))
145 if (sk->sk_bound_dev_if) {
146 if (sk->sk_bound_dev_if != dif)
152 if (score > hiscore) {
161 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
163 /* called with local bh disabled */
164 static int __inet_check_established(struct inet_timewait_death_row *death_row,
165 struct sock *sk, __u16 lport,
166 struct inet_timewait_sock **twp)
168 struct inet_hashinfo *hinfo = death_row->hashinfo;
169 struct inet_sock *inet = inet_sk(sk);
170 u32 daddr = inet->rcv_saddr;
171 u32 saddr = inet->daddr;
172 int dif = sk->sk_bound_dev_if;
173 INET_ADDR_COOKIE(acookie, saddr, daddr)
174 const __u32 ports = INET_COMBINED_PORTS(inet->dport, lport);
175 unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);
176 struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
178 const struct hlist_node *node;
179 struct inet_timewait_sock *tw;
181 prefetch(head->chain.first);
182 write_lock(&head->lock);
184 /* Check TIME-WAIT sockets first. */
185 sk_for_each(sk2, node, &(head + hinfo->ehash_size)->chain) {
188 if (INET_TW_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) {
189 if (twsk_unique(sk, sk2, twp))
197 /* And established part... */
198 sk_for_each(sk2, node, &head->chain) {
199 if (INET_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif))
204 /* Must record num and sport now. Otherwise we will see
205 * in hash table socket with a funny identity. */
207 inet->sport = htons(lport);
209 BUG_TRAP(sk_unhashed(sk));
210 __sk_add_node(sk, &head->chain);
211 sock_prot_inc_use(sk->sk_prot);
212 write_unlock(&head->lock);
216 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
218 /* Silly. Should hash-dance instead... */
219 inet_twsk_deschedule(tw, death_row);
220 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
228 write_unlock(&head->lock);
229 return -EADDRNOTAVAIL;
232 static inline u32 inet_sk_port_offset(const struct sock *sk)
234 const struct inet_sock *inet = inet_sk(sk);
235 return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,
240 * Bind a port for a connect operation and hash it.
242 int inet_hash_connect(struct inet_timewait_death_row *death_row,
245 struct inet_hashinfo *hinfo = death_row->hashinfo;
246 const unsigned short snum = inet_sk(sk)->num;
247 struct inet_bind_hashbucket *head;
248 struct inet_bind_bucket *tb;
252 int low = sysctl_local_port_range[0];
253 int high = sysctl_local_port_range[1];
254 int range = high - low;
258 u32 offset = hint + inet_sk_port_offset(sk);
259 struct hlist_node *node;
260 struct inet_timewait_sock *tw = NULL;
263 for (i = 1; i <= range; i++) {
264 port = low + (i + offset) % range;
265 head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
266 spin_lock(&head->lock);
268 /* Does not bother with rcv_saddr checks,
269 * because the established check is already
272 inet_bind_bucket_for_each(tb, node, &head->chain) {
273 if (tb->port == port) {
274 BUG_TRAP(!hlist_empty(&tb->owners));
275 if (tb->fastreuse >= 0)
277 if (!__inet_check_established(death_row,
285 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, head, port);
287 spin_unlock(&head->lock);
294 spin_unlock(&head->lock);
298 return -EADDRNOTAVAIL;
303 /* Head lock still held and bh's disabled */
304 inet_bind_hash(sk, tb, port);
305 if (sk_unhashed(sk)) {
306 inet_sk(sk)->sport = htons(port);
307 __inet_hash(hinfo, sk, 0);
309 spin_unlock(&head->lock);
312 inet_twsk_deschedule(tw, death_row);
320 head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)];
321 tb = inet_csk(sk)->icsk_bind_hash;
322 spin_lock_bh(&head->lock);
323 if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
324 __inet_hash(hinfo, sk, 0);
325 spin_unlock_bh(&head->lock);
328 spin_unlock(&head->lock);
329 /* No definite answer... Walk to established hash table */
330 ret = __inet_check_established(death_row, sk, snum, NULL);
337 EXPORT_SYMBOL_GPL(inet_hash_connect);