Bluetooth: Fix MITM protection requirement preservation

If an existing connection has a MITM protection requirement (the first
bit of the auth_type) then that requirement should not be cleared by new
sockets that reuse the ACL but don't have that requirement.

Signed-off-by: Johan Hedberg <johan.hedberg@nokia.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

net/bluetooth/hci_conn.c

@@ -442,6 +442,9 @@ static int hci_conn_auth(struct hci_conn *conn, __u8 sec_level, __u8 auth_type)
 	else if (conn->link_mode & HCI_LM_AUTH)
 		return 1;
 
+	/* Make sure we preserve an existing MITM requirement*/
+	auth_type |= (conn->auth_type & 0x01);
+
 	conn->auth_type = auth_type;
 
 	if (!test_and_set_bit(HCI_CONN_AUTH_PEND, &conn->pend)) {