Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 97ce8eca authored by Lee, Chun-Yi's avatar Lee, Chun-Yi Committed by Greg Kroah-Hartman
Browse files

Bluetooth: Reject connection with the device which has same BD_ADDR 

commit 1ffc6f8cc33268731fcf9629fc4438f6db1191fc upstream.

This change is used to relieve CVE-2020-26555. The description of
the CVE:

Bluetooth legacy BR/EDR PIN code pairing in Bluetooth Core Specification
1.0B through 5.2 may permit an unauthenticated nearby device to spoof
the BD_ADDR of the peer device to complete pairing without knowledge
of the PIN. [1]

The detail of this attack is in IEEE paper:
BlueMirror: Reflections on Bluetooth Pairing and Provisioning Protocols
[2]

It's a reflection attack. The paper mentioned that attacker can induce
the attacked target to generate null link key (zero key) without PIN
code. In BR/EDR, the key generation is actually handled in the controller
which is below HCI.

A condition of this attack is that attacker should change the
BR_ADDR of his hacking device (Host B) to equal to the BR_ADDR with
the target device being attacked (Host A).

Thus, we reject the connection with device which has same BD_ADDR
both on HCI_Create_Connection and HCI_Connection_Request to prevent
the attack. A similar implementation also shows in btstack project.
[3][4]

Cc: stable@vger.kernel.org
Link: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26555 [1]
Link: https://ieeexplore.ieee.org/abstract/document/9474325/authors#authors [2]
Link: https://github.com/bluekitchen/btstack/blob/master/src/hci.c#L3523 [3]
Link: https://github.com/bluekitchen/btstack/blob/master/src/hci.c#L7297

 [4]
Signed-off-by: default avatarLee, Chun-Yi <jlee@suse.com>
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6ce34783

net/bluetooth/hci_conn.c

+9 −0
Original line number Diff line number Diff line
@@ -1207,6 +1207,15 @@ struct hci_conn *hci_connect_acl(struct hci_dev *hdev, bdaddr_t *dst, 
		return ERR_PTR(-EOPNOTSUPP);

	}



	/* Reject outgoing connection to device with same BD ADDR against

	 * CVE-2020-26555

	 */

	if (!bacmp(&hdev->bdaddr, dst)) {

		bt_dev_dbg(hdev, "Reject connection with same BD_ADDR %pMR\n",

			   dst);

		return ERR_PTR(-ECONNREFUSED);

	}



	acl = hci_conn_hash_lookup_ba(hdev, ACL_LINK, dst);

	if (!acl) {

		acl = hci_conn_add(hdev, ACL_LINK, dst, HCI_ROLE_MASTER);

net/bluetooth/hci_event.c

+11 −0
Original line number Diff line number Diff line
@@ -2594,6 +2594,17 @@ static void hci_conn_request_evt(struct hci_dev *hdev, struct sk_buff *skb) 
	BT_DBG("%s bdaddr %pMR type 0x%x", hdev->name, &ev->bdaddr,

	       ev->link_type);



	/* Reject incoming connection from device with same BD ADDR against

	 * CVE-2020-26555

	 */

	if (!bacmp(&hdev->bdaddr, &ev->bdaddr))

	{

		bt_dev_dbg(hdev, "Reject connection with same BD_ADDR %pMR\n",

			   &ev->bdaddr);

		hci_reject_conn(hdev, &ev->bdaddr);

		return;

	}



	mask |= hci_proto_connect_ind(hdev, &ev->bdaddr, ev->link_type,

				      &flags);