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