We have a BT headset (Lenovo Thinkplus XT99), the pairing and connecting has no problem, once this headset is paired, bluez will remember this device and will auto re-connect it whenever the device is power on. The auto re-connecting works well with Windows and Android, but with Linux, it always fails. Through debugging, we found at the rfcomm connection stage, the bluetooth stack reports "Connection refused - security block (0x0003)". For this device, the re-connecting negotiation process is different from other BT headsets, it sends the Link_KEY_REQUEST command before the CONNECT_REQUEST completes, and it doesn't send ENCRYPT_CHANGE command during the negotiation. When the device sends the "connect complete" to hci, the ev->encr_mode is 1. So here in the conn_complete_evt(), if ev->encr_mode is 1, link type is ACL and HCI_CONN_ENCRYPT is not set, we set HCI_CONN_ENCRYPT to this conn, and update conn->enc_key_size accordingly. After this change, this BT headset could re-connect with Linux successfully. Signed-off-by: Hui Wang <hui.wang@xxxxxxxxxxxxx> --- This is the btmon log for auto re-connecting negotiation: Before applying this patch: https://pastebin.com/NUa9RJv8 After applying the patch: https://pastebin.com/GqviChTC net/bluetooth/hci_event.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index 4ae224824012..0c45beb08cb2 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -3208,6 +3208,32 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data, if (test_bit(HCI_ENCRYPT, &hdev->flags)) set_bit(HCI_CONN_ENCRYPT, &conn->flags); + /* "Link key request" completed ahead of "connect request" completes */ + if (ev->encr_mode == 1 && !test_bit(HCI_CONN_ENCRYPT, &conn->flags) && + ev->link_type == ACL_LINK) { + struct link_key *key; + struct hci_cp_read_enc_key_size cp; + + key = hci_find_link_key(hdev, &ev->bdaddr); + if (key) { + set_bit(HCI_CONN_ENCRYPT, &conn->flags); + + if (!(hdev->commands[20] & 0x10)) { + conn->enc_key_size = HCI_LINK_KEY_SIZE; + goto notify; + } + + cp.handle = cpu_to_le16(conn->handle); + if (hci_send_cmd(hdev, HCI_OP_READ_ENC_KEY_SIZE, + sizeof(cp), &cp)) { + bt_dev_err(hdev, "sending read key size failed"); + conn->enc_key_size = HCI_LINK_KEY_SIZE; + } +notify: + hci_encrypt_cfm(conn, ev->status); + } + } + /* Get remote features */ if (conn->type == ACL_LINK) { struct hci_cp_read_remote_features cp; -- 2.34.1
