1 files changed, 526 insertions, 0 deletions

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
new file mode 100644
index 0000000..4498190
--- /dev/null
+++ b/net/ipv4/inet_hashtables.c
@@ -0,0 +1,526 @@
+/*
+ * 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(struct kmem_cache *cachep,
+						 struct net *net,
+						 struct inet_bind_hashbucket *head,
+						 const unsigned short snum)
+{
+	struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
+
+	if (tb != NULL) {
+		tb->ib_net       = hold_net(net);
+		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(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
+{
+	if (hlist_empty(&tb->owners)) {
+		__hlist_del(&tb->node);
+		release_net(tb->ib_net);
+		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 sock *sk)
+{
+	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+	const int bhash = inet_bhashfn(sock_net(sk), 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 sock *sk)
+{
+	local_bh_disable();
+	__inet_put_port(sk);
+	local_bh_enable();
+}
+
+EXPORT_SYMBOL(inet_put_port);
+
+void __inet_inherit_port(struct sock *sk, struct sock *child)
+{
+	struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
+	const int bhash = inet_bhashfn(sock_net(sk), inet_sk(child)->num,
+			table->bhash_size);
+	struct inet_bind_hashbucket *head = &table->bhash[bhash];
+	struct inet_bind_bucket *tb;
+
+	spin_lock(&head->lock);
+	tb = inet_csk(sk)->icsk_bind_hash;
+	sk_add_bind_node(child, &tb->owners);
+	inet_csk(child)->icsk_bind_hash = tb;
+	spin_unlock(&head->lock);
+}
+
+EXPORT_SYMBOL_GPL(__inet_inherit_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)
+	__acquires(hashinfo->lhash_lock)
+{
+	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);
+	}
+}
+
+/*
+ * 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.
+ */
+static struct sock *inet_lookup_listener_slow(struct net *net,
+					      const struct hlist_head *head,
+					      const __be32 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 (net_eq(sock_net(sk), net) && inet->num == hnum &&
+				!ipv6_only_sock(sk)) {
+			const __be32 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;
+}
+
+/* Optimize the common listener case. */
+struct sock *__inet_lookup_listener(struct net *net,
+				    struct inet_hashinfo *hashinfo,
+				    const __be32 daddr, const unsigned short hnum,
+				    const int dif)
+{
+	struct sock *sk = NULL;
+	const struct hlist_head *head;
+
+	read_lock(&hashinfo->lhash_lock);
+	head = &hashinfo->listening_hash[inet_lhashfn(net, hnum)];
+	if (!hlist_empty(head)) {
+		const struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
+
+		if (inet->num == hnum && !sk->sk_node.next &&
+		    (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
+		    (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
+		    !sk->sk_bound_dev_if && net_eq(sock_net(sk), net))
+			goto sherry_cache;
+		sk = inet_lookup_listener_slow(net, head, daddr, hnum, dif);
+	}
+	if (sk) {
+sherry_cache:
+		sock_hold(sk);
+	}
+	read_unlock(&hashinfo->lhash_lock);
+	return sk;
+}
+EXPORT_SYMBOL_GPL(__inet_lookup_listener);
+
+struct sock * __inet_lookup_established(struct net *net,
+				  struct inet_hashinfo *hashinfo,
+				  const __be32 saddr, const __be16 sport,
+				  const __be32 daddr, const u16 hnum,
+				  const int dif)
+{
+	INET_ADDR_COOKIE(acookie, saddr, daddr)
+	const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
+	struct sock *sk;
+	const struct hlist_node *node;
+	/* Optimize here for direct hit, only listening connections can
+	 * have wildcards anyways.
+	 */
+	unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
+	struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash);
+	rwlock_t *lock = inet_ehash_lockp(hashinfo, hash);
+
+	prefetch(head->chain.first);
+	read_lock(lock);
+	sk_for_each(sk, node, &head->chain) {
+		if (INET_MATCH(sk, net, hash, acookie,
+					saddr, daddr, ports, dif))
+			goto hit; /* You sunk my battleship! */
+	}
+
+	/* Must check for a TIME_WAIT'er before going to listener hash. */
+	sk_for_each(sk, node, &head->twchain) {
+		if (INET_TW_MATCH(sk, net, hash, acookie,
+					saddr, daddr, ports, dif))
+			goto hit;
+	}
+	sk = NULL;
+out:
+	read_unlock(lock);
+	return sk;
+hit:
+	sock_hold(sk);
+	goto out;
+}
+EXPORT_SYMBOL_GPL(__inet_lookup_established);
+
+/* 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);
+	__be32 daddr = inet->rcv_saddr;
+	__be32 saddr = inet->daddr;
+	int dif = sk->sk_bound_dev_if;
+	INET_ADDR_COOKIE(acookie, saddr, daddr)
+	const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport);
+	struct net *net = sock_net(sk);
+	unsigned int hash = inet_ehashfn(net, daddr, lport, saddr, inet->dport);
+	struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
+	rwlock_t *lock = inet_ehash_lockp(hinfo, hash);
+	struct sock *sk2;
+	const struct hlist_node *node;
+	struct inet_timewait_sock *tw;
+
+	prefetch(head->chain.first);
+	write_lock(lock);
+
+	/* Check TIME-WAIT sockets first. */
+	sk_for_each(sk2, node, &head->twchain) {
+		tw = inet_twsk(sk2);
+
+		if (INET_TW_MATCH(sk2, net, 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, net, 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;
+	WARN_ON(!sk_unhashed(sk));
+	__sk_add_node(sk, &head->chain);
+	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
+	write_unlock(lock);
+
+	if (twp) {
+		*twp = tw;
+		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
+	} else if (tw) {
+		/* Silly. Should hash-dance instead... */
+		inet_twsk_deschedule(tw, death_row);
+		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
+
+		inet_twsk_put(tw);
+	}
+
+	return 0;
+
+not_unique:
+	write_unlock(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);
+}
+
+void __inet_hash_nolisten(struct sock *sk)
+{
+	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+	struct hlist_head *list;
+	rwlock_t *lock;
+	struct inet_ehash_bucket *head;
+
+	WARN_ON(!sk_unhashed(sk));
+
+	sk->sk_hash = inet_sk_ehashfn(sk);
+	head = inet_ehash_bucket(hashinfo, sk->sk_hash);
+	list = &head->chain;
+	lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
+
+	write_lock(lock);
+	__sk_add_node(sk, list);
+	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
+	write_unlock(lock);
+}
+EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
+
+static void __inet_hash(struct sock *sk)
+{
+	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+	struct hlist_head *list;
+	rwlock_t *lock;
+
+	if (sk->sk_state != TCP_LISTEN) {
+		__inet_hash_nolisten(sk);
+		return;
+	}
+
+	WARN_ON(!sk_unhashed(sk));
+	list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
+	lock = &hashinfo->lhash_lock;
+
+	inet_listen_wlock(hashinfo);
+	__sk_add_node(sk, list);
+	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
+	write_unlock(lock);
+	wake_up(&hashinfo->lhash_wait);
+}
+
+void inet_hash(struct sock *sk)
+{
+	if (sk->sk_state != TCP_CLOSE) {
+		local_bh_disable();
+		__inet_hash(sk);
+		local_bh_enable();
+	}
+}
+EXPORT_SYMBOL_GPL(inet_hash);
+
+void inet_unhash(struct sock *sk)
+{
+	rwlock_t *lock;
+	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+
+	if (sk_unhashed(sk))
+		goto out;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		local_bh_disable();
+		inet_listen_wlock(hashinfo);
+		lock = &hashinfo->lhash_lock;
+	} else {
+		lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
+		write_lock_bh(lock);
+	}
+
+	if (__sk_del_node_init(sk))
+		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+	write_unlock_bh(lock);
+out:
+	if (sk->sk_state == TCP_LISTEN)
+		wake_up(&hashinfo->lhash_wait);
+}
+EXPORT_SYMBOL_GPL(inet_unhash);
+
+int __inet_hash_connect(struct inet_timewait_death_row *death_row,
+		struct sock *sk, u32 port_offset,
+		int (*check_established)(struct inet_timewait_death_row *,
+			struct sock *, __u16, struct inet_timewait_sock **),
+		void (*hash)(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;
+	struct net *net = sock_net(sk);
+
+	if (!snum) {
+		int i, remaining, low, high, port;
+		static u32 hint;
+		u32 offset = hint + port_offset;
+		struct hlist_node *node;
+		struct inet_timewait_sock *tw = NULL;
+
+		inet_get_local_port_range(&low, &high);
+		remaining = (high - low) + 1;
+
+		local_bh_disable();
+		for (i = 1; i <= remaining; i++) {
+			port = low + (i + offset) % remaining;
+			head = &hinfo->bhash[inet_bhashfn(net, 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->ib_net == net && tb->port == port) {
+					WARN_ON(hlist_empty(&tb->owners));
+					if (tb->fastreuse >= 0)
+						goto next_port;
+					if (!check_established(death_row, sk,
+								port, &tw))
+						goto ok;
+					goto next_port;
+				}
+			}
+
+			tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
+					net, 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);
+			hash(sk);
+		}
+		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(net, 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) {
+		hash(sk);
+		spin_unlock_bh(&head->lock);
+		return 0;
+	} else {
+		spin_unlock(&head->lock);
+		/* No definite answer... Walk to established hash table */
+		ret = check_established(death_row, sk, snum, NULL);
+out:
+		local_bh_enable();
+		return ret;
+	}
+}
+
+/*
+ * Bind a port for a connect operation and hash it.
+ */
+int inet_hash_connect(struct inet_timewait_death_row *death_row,
+		      struct sock *sk)
+{
+	return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
+			__inet_check_established, __inet_hash_nolisten);
+}
+
+EXPORT_SYMBOL_GPL(inet_hash_connect);