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343 lines
8.8 KiB
343 lines
8.8 KiB
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Generic INET transport hashtables
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*
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* Authors: Lotsa people, from code originally in tcp
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/random.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/wait.h>
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#include <net/inet_connection_sock.h>
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#include <net/inet_hashtables.h>
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#include <net/ip.h>
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/*
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* Allocate and initialize a new local port bind bucket.
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* The bindhash mutex for snum's hash chain must be held here.
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*/
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struct inet_bind_bucket *inet_bind_bucket_create(kmem_cache_t *cachep,
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struct inet_bind_hashbucket *head,
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const unsigned short snum)
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{
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struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, SLAB_ATOMIC);
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if (tb != NULL) {
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tb->port = snum;
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tb->fastreuse = 0;
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INIT_HLIST_HEAD(&tb->owners);
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hlist_add_head(&tb->node, &head->chain);
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}
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return tb;
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}
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EXPORT_SYMBOL(inet_bind_bucket_create);
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/*
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* Caller must hold hashbucket lock for this tb with local BH disabled
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*/
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void inet_bind_bucket_destroy(kmem_cache_t *cachep, struct inet_bind_bucket *tb)
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{
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if (hlist_empty(&tb->owners)) {
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__hlist_del(&tb->node);
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kmem_cache_free(cachep, tb);
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}
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}
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void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
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const unsigned short snum)
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{
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inet_sk(sk)->num = snum;
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sk_add_bind_node(sk, &tb->owners);
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inet_csk(sk)->icsk_bind_hash = tb;
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}
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EXPORT_SYMBOL(inet_bind_hash);
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/*
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* Get rid of any references to a local port held by the given sock.
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*/
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static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
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{
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const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size);
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struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
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struct inet_bind_bucket *tb;
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spin_lock(&head->lock);
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tb = inet_csk(sk)->icsk_bind_hash;
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__sk_del_bind_node(sk);
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inet_csk(sk)->icsk_bind_hash = NULL;
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inet_sk(sk)->num = 0;
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inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
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spin_unlock(&head->lock);
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}
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void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
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{
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local_bh_disable();
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__inet_put_port(hashinfo, sk);
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local_bh_enable();
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}
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EXPORT_SYMBOL(inet_put_port);
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/*
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* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
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* Look, when several writers sleep and reader wakes them up, all but one
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* immediately hit write lock and grab all the cpus. Exclusive sleep solves
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* this, _but_ remember, it adds useless work on UP machines (wake up each
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* exclusive lock release). It should be ifdefed really.
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*/
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void inet_listen_wlock(struct inet_hashinfo *hashinfo)
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{
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write_lock(&hashinfo->lhash_lock);
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if (atomic_read(&hashinfo->lhash_users)) {
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DEFINE_WAIT(wait);
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for (;;) {
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prepare_to_wait_exclusive(&hashinfo->lhash_wait,
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&wait, TASK_UNINTERRUPTIBLE);
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if (!atomic_read(&hashinfo->lhash_users))
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break;
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write_unlock_bh(&hashinfo->lhash_lock);
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schedule();
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write_lock_bh(&hashinfo->lhash_lock);
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}
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finish_wait(&hashinfo->lhash_wait, &wait);
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}
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}
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EXPORT_SYMBOL(inet_listen_wlock);
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/*
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* Don't inline this cruft. Here are some nice properties to exploit here. The
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* BSD API does not allow a listening sock to specify the remote port nor the
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* remote address for the connection. So always assume those are both
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* wildcarded during the search since they can never be otherwise.
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*/
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struct sock *__inet_lookup_listener(const struct hlist_head *head, const u32 daddr,
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const unsigned short hnum, const int dif)
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{
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struct sock *result = NULL, *sk;
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const struct hlist_node *node;
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int hiscore = -1;
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sk_for_each(sk, node, head) {
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const struct inet_sock *inet = inet_sk(sk);
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if (inet->num == hnum && !ipv6_only_sock(sk)) {
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const __u32 rcv_saddr = inet->rcv_saddr;
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int score = sk->sk_family == PF_INET ? 1 : 0;
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if (rcv_saddr) {
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if (rcv_saddr != daddr)
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continue;
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score += 2;
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}
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if (sk->sk_bound_dev_if) {
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if (sk->sk_bound_dev_if != dif)
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continue;
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score += 2;
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}
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if (score == 5)
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return sk;
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if (score > hiscore) {
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hiscore = score;
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result = sk;
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}
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}
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}
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return result;
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}
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EXPORT_SYMBOL_GPL(__inet_lookup_listener);
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/* called with local bh disabled */
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static int __inet_check_established(struct inet_timewait_death_row *death_row,
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struct sock *sk, __u16 lport,
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struct inet_timewait_sock **twp)
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{
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struct inet_hashinfo *hinfo = death_row->hashinfo;
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struct inet_sock *inet = inet_sk(sk);
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u32 daddr = inet->rcv_saddr;
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u32 saddr = inet->daddr;
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int dif = sk->sk_bound_dev_if;
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INET_ADDR_COOKIE(acookie, saddr, daddr)
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const __u32 ports = INET_COMBINED_PORTS(inet->dport, lport);
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unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);
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struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
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struct sock *sk2;
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const struct hlist_node *node;
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struct inet_timewait_sock *tw;
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prefetch(head->chain.first);
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write_lock(&head->lock);
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/* Check TIME-WAIT sockets first. */
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sk_for_each(sk2, node, &(head + hinfo->ehash_size)->chain) {
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tw = inet_twsk(sk2);
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if (INET_TW_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) {
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if (twsk_unique(sk, sk2, twp))
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goto unique;
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else
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goto not_unique;
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}
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}
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tw = NULL;
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/* And established part... */
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sk_for_each(sk2, node, &head->chain) {
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if (INET_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif))
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goto not_unique;
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}
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unique:
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/* Must record num and sport now. Otherwise we will see
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* in hash table socket with a funny identity. */
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inet->num = lport;
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inet->sport = htons(lport);
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sk->sk_hash = hash;
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BUG_TRAP(sk_unhashed(sk));
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__sk_add_node(sk, &head->chain);
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sock_prot_inc_use(sk->sk_prot);
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write_unlock(&head->lock);
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if (twp) {
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*twp = tw;
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NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
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} else if (tw) {
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/* Silly. Should hash-dance instead... */
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inet_twsk_deschedule(tw, death_row);
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NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
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inet_twsk_put(tw);
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}
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return 0;
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not_unique:
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write_unlock(&head->lock);
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return -EADDRNOTAVAIL;
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}
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static inline u32 inet_sk_port_offset(const struct sock *sk)
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{
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const struct inet_sock *inet = inet_sk(sk);
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return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,
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inet->dport);
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}
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/*
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* Bind a port for a connect operation and hash it.
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*/
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int inet_hash_connect(struct inet_timewait_death_row *death_row,
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struct sock *sk)
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{
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struct inet_hashinfo *hinfo = death_row->hashinfo;
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const unsigned short snum = inet_sk(sk)->num;
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struct inet_bind_hashbucket *head;
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struct inet_bind_bucket *tb;
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int ret;
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if (!snum) {
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int low = sysctl_local_port_range[0];
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int high = sysctl_local_port_range[1];
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int range = high - low;
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int i;
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int port;
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static u32 hint;
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u32 offset = hint + inet_sk_port_offset(sk);
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struct hlist_node *node;
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struct inet_timewait_sock *tw = NULL;
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local_bh_disable();
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for (i = 1; i <= range; i++) {
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port = low + (i + offset) % range;
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head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
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spin_lock(&head->lock);
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/* Does not bother with rcv_saddr checks,
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* because the established check is already
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* unique enough.
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*/
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inet_bind_bucket_for_each(tb, node, &head->chain) {
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if (tb->port == port) {
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BUG_TRAP(!hlist_empty(&tb->owners));
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if (tb->fastreuse >= 0)
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goto next_port;
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if (!__inet_check_established(death_row,
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sk, port,
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&tw))
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goto ok;
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goto next_port;
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}
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}
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tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, head, port);
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if (!tb) {
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spin_unlock(&head->lock);
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break;
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}
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tb->fastreuse = -1;
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goto ok;
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next_port:
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spin_unlock(&head->lock);
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}
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local_bh_enable();
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return -EADDRNOTAVAIL;
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ok:
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hint += i;
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/* Head lock still held and bh's disabled */
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inet_bind_hash(sk, tb, port);
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if (sk_unhashed(sk)) {
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inet_sk(sk)->sport = htons(port);
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__inet_hash(hinfo, sk, 0);
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}
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spin_unlock(&head->lock);
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if (tw) {
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inet_twsk_deschedule(tw, death_row);
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inet_twsk_put(tw);
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}
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ret = 0;
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goto out;
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}
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head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)];
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tb = inet_csk(sk)->icsk_bind_hash;
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spin_lock_bh(&head->lock);
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if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
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__inet_hash(hinfo, sk, 0);
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spin_unlock_bh(&head->lock);
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return 0;
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} else {
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spin_unlock(&head->lock);
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/* No definite answer... Walk to established hash table */
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ret = __inet_check_established(death_row, sk, snum, NULL);
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out:
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local_bh_enable();
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return ret;
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}
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}
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EXPORT_SYMBOL_GPL(inet_hash_connect);
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