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/config.h> 17 #include <linux/module.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 25 /* 26 * Allocate and initialize a new local port bind bucket. 27 * The bindhash mutex for snum's hash chain must be held here. 28 */ 29 struct inet_bind_bucket *inet_bind_bucket_create(kmem_cache_t *cachep, 30 struct inet_bind_hashbucket *head, 31 const unsigned short snum) 32 { 33 struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, SLAB_ATOMIC); 34 35 if (tb != NULL) { 36 tb->port = snum; 37 tb->fastreuse = 0; 38 INIT_HLIST_HEAD(&tb->owners); 39 hlist_add_head(&tb->node, &head->chain); 40 } 41 return tb; 42 } 43 44 EXPORT_SYMBOL(inet_bind_bucket_create); 45 46 /* 47 * Caller must hold hashbucket lock for this tb with local BH disabled 48 */ 49 void inet_bind_bucket_destroy(kmem_cache_t *cachep, struct inet_bind_bucket *tb) 50 { 51 if (hlist_empty(&tb->owners)) { 52 __hlist_del(&tb->node); 53 kmem_cache_free(cachep, tb); 54 } 55 } 56 57 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 58 const unsigned short snum) 59 { 60 inet_sk(sk)->num = snum; 61 sk_add_bind_node(sk, &tb->owners); 62 inet_csk(sk)->icsk_bind_hash = tb; 63 } 64 65 EXPORT_SYMBOL(inet_bind_hash); 66 67 /* 68 * Get rid of any references to a local port held by the given sock. 69 */ 70 static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk) 71 { 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 inet_hashinfo *hashinfo, struct sock *sk) 86 { 87 local_bh_disable(); 88 __inet_put_port(hashinfo, 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 { 103 write_lock(&hashinfo->lhash_lock); 104 105 if (atomic_read(&hashinfo->lhash_users)) { 106 DEFINE_WAIT(wait); 107 108 for (;;) { 109 prepare_to_wait_exclusive(&hashinfo->lhash_wait, 110 &wait, TASK_UNINTERRUPTIBLE); 111 if (!atomic_read(&hashinfo->lhash_users)) 112 break; 113 write_unlock_bh(&hashinfo->lhash_lock); 114 schedule(); 115 write_lock_bh(&hashinfo->lhash_lock); 116 } 117 118 finish_wait(&hashinfo->lhash_wait, &wait); 119 } 120 } 121 122 EXPORT_SYMBOL(inet_listen_wlock); 123 124 /* 125 * Don't inline this cruft. Here are some nice properties to exploit here. The 126 * BSD API does not allow a listening sock to specify the remote port nor the 127 * remote address for the connection. So always assume those are both 128 * wildcarded during the search since they can never be otherwise. 129 */ 130 struct sock *__inet_lookup_listener(const struct hlist_head *head, const u32 daddr, 131 const unsigned short hnum, const int dif) 132 { 133 struct sock *result = NULL, *sk; 134 const struct hlist_node *node; 135 int hiscore = -1; 136 137 sk_for_each(sk, node, head) { 138 const struct inet_sock *inet = inet_sk(sk); 139 140 if (inet->num == hnum && !ipv6_only_sock(sk)) { 141 const __u32 rcv_saddr = inet->rcv_saddr; 142 int score = sk->sk_family == PF_INET ? 1 : 0; 143 144 if (rcv_saddr) { 145 if (rcv_saddr != daddr) 146 continue; 147 score += 2; 148 } 149 if (sk->sk_bound_dev_if) { 150 if (sk->sk_bound_dev_if != dif) 151 continue; 152 score += 2; 153 } 154 if (score == 5) 155 return sk; 156 if (score > hiscore) { 157 hiscore = score; 158 result = sk; 159 } 160 } 161 } 162 return result; 163 } 164 165 EXPORT_SYMBOL_GPL(__inet_lookup_listener); 166