950-0429-Bluetooth-Check-key-sizes-only-when-Secure-Simple-Pa.patch

From 83f0a8986ae42e33bc16acda0451dce2cf4dfb55 Mon Sep 17 00:00:00 2001
From: Marcel Holtmann <marcel@holtmann.org>
Date: Wed, 22 May 2019 09:05:40 +0200
Subject: [PATCH] Bluetooth: Check key sizes only when Secure Simple
 Pairing is enabled

The encryption is only mandatory to be enforced when both sides are using
Secure Simple Pairing and this means the key size check makes only sense
in that case.

On legacy Bluetooth 2.0 and earlier devices like mice the encryption was
optional and thus causing an issue if the key size check is not bound to
using Secure Simple Pairing.

Fixes: d5bb334a8e17 ("Bluetooth: Align minimum encryption key size for LE and BR/EDR connections")
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org
---
 net/bluetooth/hci_conn.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1272,8 +1272,13 @@ int hci_conn_check_link_mode(struct hci_
 			return 0;
 	}
 
-	if (hci_conn_ssp_enabled(conn) &&
-	    !test_bit(HCI_CONN_ENCRYPT, &conn->flags))
+	/* If Secure Simple Pairing is not enabled, then legacy connection
+	 * setup is used and no encryption or key sizes can be enforced.
+	 */
+	if (!hci_conn_ssp_enabled(conn))
+		return 1;
+
+	if (!test_bit(HCI_CONN_ENCRYPT, &conn->flags))
 		return 0;
 
 	return 1;