Merge branch 'tcp-fix-bind-regression-and-more-tests'

Kuniyuki Iwashima says:

====================
tcp: Fix bind() regression and more tests.

bhash2 has not been well tested for IPV6_V6ONLY option.

This series fixes two regression around IPV6_V6ONLY, one of which
has been there since bhash2 introduction, and another is introduced
by a recent change.

Also, this series adds as many tests as possible to catch regression
easily.  The baseline is 28044fc1~ which is pre-bhash2 commit.

 Tested on 28044fc1~:
  # PASSED: 132 / 132 tests passed.
  # Totals: pass:132 fail:0 xfail:0 xpass:0 skip:0 error:0

 net.git:
  # FAILED: 125 / 132 tests passed.
  # Totals: pass:125 fail:7 xfail:0 xpass:0 skip:0 error:0

 With this series:
  # PASSED: 132 / 132 tests passed.
  # Totals: pass:132 fail:0 xfail:0 xpass:0 skip:0 error:0

v1: https://lore.kernel.org/netdev/20240325181923.48769-1-kuniyu@amazon.com/
====================

Link: https://lore.kernel.org/r/20240326204251.51301-1-kuniyu@amazon.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/inet_connection_sock.c

@@ -203,8 +203,15 @@ static bool __inet_bhash2_conflict(const struct sock *sk, struct sock *sk2,
 				   kuid_t sk_uid, bool relax,
 				   bool reuseport_cb_ok, bool reuseport_ok)
 {
-	if (sk->sk_family == AF_INET && ipv6_only_sock(sk2))
-		return false;
+	if (ipv6_only_sock(sk2)) {
+		if (sk->sk_family == AF_INET)
+			return false;
+
+#if IS_ENABLED(CONFIG_IPV6)
+		if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
+			return false;
+#endif
+	}
 
 	return inet_bind_conflict(sk, sk2, sk_uid, relax,
 				  reuseport_cb_ok, reuseport_ok);
@@ -287,6 +294,7 @@ static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l
 	struct sock_reuseport *reuseport_cb;
 	struct inet_bind_hashbucket *head2;
 	struct inet_bind2_bucket *tb2;
+	bool conflict = false;
 	bool reuseport_cb_ok;
 
 	rcu_read_lock();
@@ -299,18 +307,20 @@ static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l
 
 	spin_lock(&head2->lock);
 
-	inet_bind_bucket_for_each(tb2, &head2->chain)
-		if (inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
-			break;
+	inet_bind_bucket_for_each(tb2, &head2->chain) {
+		if (!inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
+			continue;
 
-	if (tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
-					reuseport_ok)) {
-		spin_unlock(&head2->lock);
-		return true;
+		if (!inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,	reuseport_ok))
+			continue;
+
+		conflict = true;
+		break;
 	}
 
 	spin_unlock(&head2->lock);
-	return false;
+
+	return conflict;
 }
 
 /*