2019-04-24 20:19:23

by Marcel Holtmann

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

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 <[email protected]>
---
include/net/bluetooth/hci_core.h | 3 +++
net/bluetooth/hci_conn.c | 8 ++++++++
2 files changed, 11 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 094e61e07030..05b1b96f4d9e 100644
--- 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)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index bd4978ce8c45..3cf0764d5793 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1276,6 +1276,14 @@ int hci_conn_check_link_mode(struct hci_conn *conn)
!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;
}

--
2.20.1

2019-04-25 14:11:40

by Johan Hedberg

Subject: Re: [PATCH] Bluetooth: Align minimum encryption key size for LE and BR/EDR connections

Hi Marcel,

On Wed, Apr 24, 2019, Marcel Holtmann wrote:
> 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 <[email protected]>
> ---
> include/net/bluetooth/hci_core.h | 3 +++
> net/bluetooth/hci_conn.c | 8 ++++++++
> 2 files changed, 11 insertions(+)

Applied to bluetooth-next. Thanks.

Johan