Skip to content

L
linux
Switch branch/tag
  1. 09 Sep, 2008 3 commits
    • Marcel Holtmann's avatar
      [Bluetooth] Reject L2CAP connections on an insecure ACL link · e7c29cb1
      Marcel Holtmann authored 
      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: default avatarMarcel Holtmann <marcel@holtmann.org>
      e7c29cb1
    • Marcel Holtmann's avatar
      [Bluetooth] Enforce correct authentication requirements · 09ab6f4c
      Marcel Holtmann authored 
      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: default avatarMarcel Holtmann <marcel@holtmann.org>
      09ab6f4c
    • Marcel Holtmann's avatar
      [Bluetooth] Fix reference counting during ACL config stage · f1c08ca5
      Marcel Holtmann authored 
      The ACL config stage keeps holding a reference count on incoming
connections when requesting the extended features. This results in
keeping an ACL link up without any users. The problem here is that
the Bluetooth specification doesn't define an ownership of the ACL
link and thus it can happen that the implementation on the initiator
side doesn't care about disconnecting unused links. In this case the
acceptor needs to take care of this.
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
      f1c08ca5
  3. 28 Aug, 2008 17 commits
  5. 27 Aug, 2008 20 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7