[PATCH 5.0 88/95] Bluetooth: Align minimum encryption key size for LE and BR/EDR connections

Greg Kroah-Hartman
2019-05-09T18:58:03Z

From: Marcel Holtmann <marcel@holtmann.org>

commit d5bb334a8e171b262e48f378bd2096c0ea458265 upstream.

The minimum encryption key size for LE connections is 56 bits and to
align LE with BR/EDR, enforce 56 bits of minimum encryption key size for
BR/EDR connections as well.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/net/bluetooth/hci_core.h | 3 +++
net/bluetooth/hci_conn.c | 8 ++++++++
2 files changed, 11 insertions(+)

--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -190,6 +190,9 @@ struct adv_info {

#define HCI_MAX_SHORT_NAME_LENGTH 10

+/* Min encryption key size to match with SMP */
+#define HCI_MIN_ENC_KEY_SIZE 7
+
/* Default LE RPA expiry time, 15 minutes */
#define HCI_DEFAULT_RPA_TIMEOUT (15 * 60)

--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1276,6 +1276,14 @@ int hci_conn_check_link_mode(struct hci_
!test_bit(HCI_CONN_ENCRYPT, &conn->flags))
return 0;

+ /* The minimum encryption key size needs to be enforced by the
+ * host stack before establishing any L2CAP connections. The
+ * specification in theory allows a minimum of 1, but to align
+ * BR/EDR and LE transports, a minimum of 7 is chosen.
+ */
+ if (conn->enc_key_size < HCI_MIN_ENC_KEY_SIZE)
+ return 0;
+
return 1;
}