From 09ab6f4c2376a0fc31abde1e2991513f900ea825 Mon Sep 17 00:00:00 2001 From: Marcel Holtmann Date: Tue, 9 Sep 2008 07:19:20 +0200 Subject: [Bluetooth] Enforce correct authentication requirements With the introduction of Security Mode 4 and Simple Pairing from the Bluetooth 2.1 specification it became mandatory that the initiator requires authentication and encryption before any L2CAP channel can be established. The only exception here is PSM 1 for the service discovery protocol (SDP). It is meant to be used without any encryption since it contains only public information. This is how Bluetooth 2.0 and before handle connections on PSM 1. For Bluetooth 2.1 devices the pairing procedure differentiates between no bonding, general bonding and dedicated bonding. The L2CAP layer wrongly uses always general bonding when creating new connections, but it should not do this for SDP connections. In this case the authentication requirement should be no bonding and the just-works model should be used, but in case of non-SDP connection it is required to use general bonding. If the new connection requires man-in-the-middle (MITM) protection, it also first wrongly creates an unauthenticated link key and then later on requests an upgrade to an authenticated link key to provide full MITM protection. With Simple Pairing the link key generation is an expensive operation (compared to Bluetooth 2.0 and before) and doing this twice during a connection setup causes a noticeable delay when establishing a new connection. This should be avoided to not regress from the expected Bluetooth 2.0 connection times. The authentication requirements are known up-front and so enforce them. To fulfill these requirements the hci_connect() function has been extended with an authentication requirement parameter that will be stored inside the connection information and can be retrieved by userspace at any time. This allows the correct IO capabilities exchange and results in the expected behavior. Signed-off-by: Marcel Holtmann --- include/net/bluetooth/hci_core.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/net/bluetooth') diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h index cbf751094688..5e785b968e7e 100644 --- a/include/net/bluetooth/hci_core.h +++ b/include/net/bluetooth/hci_core.h @@ -325,7 +325,7 @@ int hci_conn_del(struct hci_conn *conn); void hci_conn_hash_flush(struct hci_dev *hdev); void hci_conn_check_pending(struct hci_dev *hdev); -struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *src); +struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8 auth_type); int hci_conn_auth(struct hci_conn *conn); int hci_conn_encrypt(struct hci_conn *conn); int hci_conn_change_link_key(struct hci_conn *conn); -- cgit v1.2.2 From e7c29cb16c833441fd2160642bb13025f4e7ac70 Mon Sep 17 00:00:00 2001 From: Marcel Holtmann Date: Tue, 9 Sep 2008 07:19:20 +0200 Subject: [Bluetooth] Reject L2CAP connections on an insecure ACL link The Security Mode 4 of the Bluetooth 2.1 specification has strict authentication and encryption requirements. It is the initiators job to create a secure ACL link. However in case of malicious devices, the acceptor has to make sure that the ACL is encrypted before allowing any kind of L2CAP connection. The only exception here is the PSM 1 for the service discovery protocol, because that is allowed to run on an insecure ACL link. Previously it was enough to reject a L2CAP connection during the connection setup phase, but with Bluetooth 2.1 it is forbidden to do any L2CAP protocol exchange on an insecure link (except SDP). The new hci_conn_check_link_mode() function can be used to check the integrity of an ACL link. This functions also takes care of the cases where Security Mode 4 is disabled or one of the devices is based on an older specification. Signed-off-by: Marcel Holtmann --- include/net/bluetooth/hci_core.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/net/bluetooth') diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h index 5e785b968e7e..46a43b721dd6 100644 --- a/include/net/bluetooth/hci_core.h +++ b/include/net/bluetooth/hci_core.h @@ -326,6 +326,7 @@ void hci_conn_hash_flush(struct hci_dev *hdev); void hci_conn_check_pending(struct hci_dev *hdev); struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8 auth_type); +int hci_conn_check_link_mode(struct hci_conn *conn); int hci_conn_auth(struct hci_conn *conn); int hci_conn_encrypt(struct hci_conn *conn); int hci_conn_change_link_key(struct hci_conn *conn); -- cgit v1.2.2