tcp: Add TIME_WAIT sockets in bhash2.

Jiri Slaby reported regression of bind() with a simple repro. [0]

The repro creates a TIME_WAIT socket and tries to bind() a new socket
with the same local address and port.  Before commit 28044fc1d495 ("net:
Add a bhash2 table hashed by port and address"), the bind() failed with
-EADDRINUSE, but now it succeeds.

The cited commit should have put TIME_WAIT sockets into bhash2; otherwise,
inet_bhash2_conflict() misses TIME_WAIT sockets when validating bind()
requests if the address is not a wildcard one.

The straight option is to move sk_bind2_node from struct sock to struct
sock_common to add twsk to bhash2 as implemented as RFC. [1]  However, the
binary layout change in the struct sock could affect performances moving
hot fields on different cachelines.

To avoid that, we add another TIME_WAIT list in inet_bind2_bucket and check
it while validating bind().

[0]: https://lore.kernel.org/netdev/6b971a4e-c7d8-411e-1f92-fda29b5b2fb9@kernel.org/
[1]: https://lore.kernel.org/netdev/20221221151258.25748-2-kuniyu@amazon.com/

Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address")
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 2 deletions

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 66fc940f9521..1d77d992e6e7 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -29,6 +29,7 @@
 void inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
 			  struct inet_hashinfo *hashinfo)
 {
+	struct inet_bind2_bucket *tb2 = tw->tw_tb2;
 	struct inet_bind_bucket *tb = tw->tw_tb;
 
 	if (!tb)
@@ -37,6 +38,11 @@ void inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
 	__hlist_del(&tw->tw_bind_node);
 	tw->tw_tb = NULL;
 	inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+
+	__hlist_del(&tw->tw_bind2_node);
+	tw->tw_tb2 = NULL;
+	inet_bind2_bucket_destroy(hashinfo->bind2_bucket_cachep, tb2);
+
 	__sock_put((struct sock *)tw);
 }
 
@@ -45,7 +51,7 @@ static void inet_twsk_kill(struct inet_timewait_sock *tw)
 {
 	struct inet_hashinfo *hashinfo = tw->tw_dr->hashinfo;
 	spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);
-	struct inet_bind_hashbucket *bhead;
+	struct inet_bind_hashbucket *bhead, *bhead2;
 
 	spin_lock(lock);
 	sk_nulls_del_node_init_rcu((struct sock *)tw);
@@ -54,9 +60,13 @@ static void inet_twsk_kill(struct inet_timewait_sock *tw)
 	/* Disassociate with bind bucket. */
 	bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num,
 			hashinfo->bhash_size)];
+	bhead2 = inet_bhashfn_portaddr(hashinfo, (struct sock *)tw,
+				       twsk_net(tw), tw->tw_num);
 
 	spin_lock(&bhead->lock);
+	spin_lock(&bhead2->lock);
 	inet_twsk_bind_unhash(tw, hashinfo);
+	spin_unlock(&bhead2->lock);
 	spin_unlock(&bhead->lock);
 
 	refcount_dec(&tw->tw_dr->tw_refcount);
@@ -93,6 +103,12 @@ static void inet_twsk_add_bind_node(struct inet_timewait_sock *tw,
 	hlist_add_head(&tw->tw_bind_node, list);
 }
 
+static void inet_twsk_add_bind2_node(struct inet_timewait_sock *tw,
+				     struct hlist_head *list)
+{
+	hlist_add_head(&tw->tw_bind2_node, list);
+}
+
 /*
  * Enter the time wait state. This is called with locally disabled BH.
  * Essentially we whip up a timewait bucket, copy the relevant info into it
@@ -105,17 +121,28 @@ void inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash);
 	spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
-	struct inet_bind_hashbucket *bhead;
+	struct inet_bind_hashbucket *bhead, *bhead2;
+
 	/* Step 1: Put TW into bind hash. Original socket stays there too.
 	   Note, that any socket with inet->num != 0 MUST be bound in
 	   binding cache, even if it is closed.
 	 */
 	bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->inet_num,
 			hashinfo->bhash_size)];
+	bhead2 = inet_bhashfn_portaddr(hashinfo, sk, twsk_net(tw), inet->inet_num);
+
 	spin_lock(&bhead->lock);
+	spin_lock(&bhead2->lock);
+
 	tw->tw_tb = icsk->icsk_bind_hash;
 	WARN_ON(!icsk->icsk_bind_hash);
 	inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
+
+	tw->tw_tb2 = icsk->icsk_bind2_hash;
+	WARN_ON(!icsk->icsk_bind2_hash);
+	inet_twsk_add_bind2_node(tw, &tw->tw_tb2->deathrow);
+
+	spin_unlock(&bhead2->lock);
 	spin_unlock(&bhead->lock);
 
 	spin_lock(lock);