This is a note to let you know that I've just added the patch titled
Bluetooth: Reject connection with the device which has same BD_ADDR
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bluetooth-reject-connection-with-the-device-which-has-same-bd_addr.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1ffc6f8cc33268731fcf9629fc4438f6db1191fc Mon Sep 17 00:00:00 2001
From: "Lee, Chun-Yi" <jlee@xxxxxxxx>
Date: Sun, 1 Oct 2023 16:59:58 +0800
Subject: Bluetooth: Reject connection with the device which has same BD_ADDR
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
@@ -1207,6 +1207,15 @@ 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
@@ -2594,6 +2594,17 @@ 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);
Patches currently in stable-queue which might be from jlee@xxxxxxxx are
queue-5.4/bluetooth-hci_event-ignore-null-link-key.patch
queue-5.4/bluetooth-reject-connection-with-the-device-which-has-same-bd_addr.patch
