Bluetooth: Align minimum encryption key size for LE and BR/EDR connections

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index b386bf17e6c2c10808c8306ad7cbb4bb42e4713d..588746487c1a04dd3539ee134c12b6b22c0e2159 100644 (file)
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -142,6 +142,9 @@ struct oob_data {
 
 #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 1cb6405e44291bd7622da065b5c88a40d6b17bbe..6b35aba737486b3e1111acc64ff09c2c0050bfe0 100644 (file)
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -868,6 +868,14 @@ int hci_conn_check_link_mode(struct hci_conn *conn)
        if (hci_conn_ssp_enabled(conn) && !(conn->link_mode & HCI_LM_ENCRYPT))
                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;
 }