[PATCH 5.15 005/137] Bluetooth: Reject connection with the device which has same BD_ADDR

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5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lee, Chun-Yi <jlee@xxxxxxxx>

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@xxxxxxxxxxxxxxx
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: Lee, Chun-Yi <jlee@xxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/bluetooth/hci_conn.c  |    9 +++++++++
 net/bluetooth/hci_event.c |   11 +++++++++++
 2 files changed, 20 insertions(+)

--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1300,6 +1300,15 @@ struct hci_conn *hci_connect_acl(struct
 		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);
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -2794,6 +2794,17 @@ static void hci_conn_request_evt(struct
 	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);
 





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