Bluetooth: Disconnect if E0 is used for Level 4

E0 is not allowed with Level 4:

BLUETOOTH CORE SPECIFICATION Version 5.2 | Vol 3, Part C page 1319:

  '128-bit equivalent strength for link and encryption keys
   required using FIPS approved algorithms (E0 not allowed,
   SAFER+ not allowed, and P-192 not allowed; encryption key
   not shortened'

SC enabled:

> HCI Event: Read Remote Extended Features (0x23) plen 13
        Status: Success (0x00)
        Handle: 256
        Page: 1/2
        Features: 0x0b 0x00 0x00 0x00 0x00 0x00 0x00 0x00
          Secure Simple Pairing (Host Support)
          LE Supported (Host)
          Secure Connections (Host Support)
> HCI Event: Encryption Change (0x08) plen 4
        Status: Success (0x00)
        Handle: 256
        Encryption: Enabled with AES-CCM (0x02)

SC disabled:

> HCI Event: Read Remote Extended Features (0x23) plen 13
        Status: Success (0x00)
        Handle: 256
        Page: 1/2
        Features: 0x03 0x00 0x00 0x00 0x00 0x00 0x00 0x00
          Secure Simple Pairing (Host Support)
          LE Supported (Host)
> HCI Event: Encryption Change (0x08) plen 4
        Status: Success (0x00)
        Handle: 256
        Encryption: Enabled with E0 (0x01)
[May 8 20:23] Bluetooth: hci0: Invalid security: expect AES but E0 was used
< HCI Command: Disconnect (0x01|0x0006) plen 3
        Handle: 256
        Reason: Authentication Failure (0x05)

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 77d2934..836dc99 100644 (file)
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1481,11 +1481,13 @@ static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
        else
                encrypt = 0x01;
 
-       if (conn->sec_level == BT_SECURITY_SDP)
-               conn->sec_level = BT_SECURITY_LOW;
+       if (!status) {
+               if (conn->sec_level == BT_SECURITY_SDP)
+                       conn->sec_level = BT_SECURITY_LOW;
 
-       if (conn->pending_sec_level > conn->sec_level)
-               conn->sec_level = conn->pending_sec_level;
+               if (conn->pending_sec_level > conn->sec_level)
+                       conn->sec_level = conn->pending_sec_level;
+       }
 
        mutex_lock(&hci_cb_list_lock);
        list_for_each_entry(cb, &hci_cb_list, list) {

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 47f3a45..8805d68 100644 (file)
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1322,6 +1322,23 @@ int hci_conn_check_link_mode(struct hci_conn *conn)
                        return 0;
        }
 
+        /* AES encryption is required for Level 4:
+         *
+         * BLUETOOTH CORE SPECIFICATION Version 5.2 | Vol 3, Part C
+         * page 1319:
+         *
+         * 128-bit equivalent strength for link and encryption keys
+         * required using FIPS approved algorithms (E0 not allowed,
+         * SAFER+ not allowed, and P-192 not allowed; encryption key
+         * not shortened)
+         */
+       if (conn->sec_level == BT_SECURITY_FIPS &&
+           !test_bit(HCI_CONN_AES_CCM, &conn->flags)) {
+               bt_dev_err(conn->hdev,
+                          "Invalid security: Missing AES-CCM usage");
+               return 0;
+       }
+
        if (hci_conn_ssp_enabled(conn) &&
            !test_bit(HCI_CONN_ENCRYPT, &conn->flags))
                return 0;

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index e08d4dd..e060fc9 100644 (file)
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3065,27 +3065,23 @@ static void hci_encrypt_change_evt(struct hci_dev *hdev, struct sk_buff *skb)
 
        clear_bit(HCI_CONN_ENCRYPT_PEND, &conn->flags);
 
+       /* Check link security requirements are met */
+       if (!hci_conn_check_link_mode(conn))
+               ev->status = HCI_ERROR_AUTH_FAILURE;
+
        if (ev->status && conn->state == BT_CONNECTED) {
                if (ev->status == HCI_ERROR_PIN_OR_KEY_MISSING)
                        set_bit(HCI_CONN_AUTH_FAILURE, &conn->flags);
 
+               /* Notify upper layers so they can cleanup before
+                * disconnecting.
+                */
+               hci_encrypt_cfm(conn, ev->status);
                hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE);
                hci_conn_drop(conn);
                goto unlock;
        }
 
-       /* In Secure Connections Only mode, do not allow any connections
-        * that are not encrypted with AES-CCM using a P-256 authenticated
-        * combination key.
-        */
-       if (hci_dev_test_flag(hdev, HCI_SC_ONLY) &&
-           (!test_bit(HCI_CONN_AES_CCM, &conn->flags) ||
-            conn->key_type != HCI_LK_AUTH_COMBINATION_P256)) {
-               hci_connect_cfm(conn, HCI_ERROR_AUTH_FAILURE);
-               hci_conn_drop(conn);
-               goto unlock;
-       }
-
        /* Try reading the encryption key size for encrypted ACL links */
        if (!ev->status && ev->encrypt && conn->type == ACL_LINK) {
                struct hci_cp_read_enc_key_size cp;