Bluetooth: ignore NULL link key and reject connection with the device which has same BD_ADDR
Subsystems (2)
cover Bluetooth: ignore NULL link key and reject connection with the device which has same BD_ADDR
This patch set 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.
Thus, we can ignore null link key in the handler of "Link Key Notification event" to relieve the attack. And, 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). So we reject the connection with device which has same BD_ADDR both on HCI_Create_Connection and HCI_Connection_Request to prevent the attack.
Similar implementations also show in btstack project. [3][4][5]
Lee, Chun-Yi (2):
Bluetooth: hci_event: Ignore NULL link key
Bluetooth: Reject connection with the device which has same BD_ADDR
net/bluetooth/hci_conn.c | 7 +++++++ net/bluetooth/hci_event.c | 16 ++++++++++++++++ 2 files changed, 23 insertions(+)
Signature · 1 line
2.35.3
PATCH 1/2 Bluetooth: hci_event: Ignore NULL link key
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.
Thus, we can ignore null link key in the handler of "Link Key Notification event" to relieve the attack. A similar implementation also shows in btstack project. [3]
v3: Drop the connection when null link key be detected.
v2:
- Used Link: tag instead of Closes:
- Used bt_dev_dbg instead of BT_DBG
- Added Fixes: tag
--- net/bluetooth/hci_event.c | 8 ++++++++ 1 file changed, 8 insertions(+)
net/bluetooth/hci_event.c +8 -0
@@ -4741,6 +4741,14 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, void *data,if (!conn) goto unlock; +/* Ignore NULL link key against CVE-2020-26555 */ +if (!memcmp (ev->link_key,ZERO_KEY ,HCI_LINK_KEY_SIZE )) { +bt_dev_dbg (hdev,"Ignore NULL link key (ZERO KEY) for %pMR" , &ev->bdaddr); +hci_disconnect (conn,HCI_ERROR_AUTH_FAILURE ); +hci_conn_drop (conn); + goto unlock; + } +hci_conn_hold (conn); conn->disc_timeout =HCI_DISCONN_TIMEOUT ;hci_conn_drop (conn);
Signature · 1 line
2.35.3
PATCH 2/2 Bluetooth: Reject connection with the device which has same BD_ADDR
In reply to Lee, Chun-YiThis 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]
--- net/bluetooth/hci_conn.c | 7 +++++++ net/bluetooth/hci_event.c | 8 ++++++++ 2 files changed, 15 insertions(+)
net/bluetooth/hci_conn.c +7 -0
@@ -1627,6 +1627,13 @@ 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 to the device 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 +8 -0
@@ -3267,6 +3267,14 @@ static void hci_conn_request_evt(struct hci_dev *hdev, void *data,bt_dev_dbg (hdev,"bdaddr %pMR type 0x%x" , &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 from the device 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);
Signature · 1 line
2.35.3
This is automated email and please do not reply to this email!
Dear submitter,
Thank you for submitting the patches to the linux bluetooth mailing list. This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=789101
---Test result---
Test Summary:
CheckPatch FAIL 2.89 seconds GitLint PASS 0.61 seconds SubjectPrefix PASS 0.20 seconds BuildKernel PASS 35.46 seconds CheckAllWarning PASS 39.10 seconds CheckSparse WARNING 44.54 seconds CheckSmatch WARNING 118.36 seconds BuildKernel32 PASS 34.21 seconds TestRunnerSetup PASS 520.60 seconds TestRunner_l2cap-tester PASS 32.09 seconds TestRunner_iso-tester PASS 55.24 seconds TestRunner_bnep-tester PASS 10.58 seconds TestRunner_mgmt-tester PASS 234.69 seconds TestRunner_rfcomm-tester PASS 16.34 seconds TestRunner_sco-tester PASS 19.67 seconds TestRunner_ioctl-tester PASS 18.91 seconds TestRunner_mesh-tester PASS 13.78 seconds TestRunner_smp-tester PASS 14.59 seconds TestRunner_userchan-tester PASS 11.30 seconds IncrementalBuild PASS 39.54 seconds
Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script
Output:
[2/2] Bluetooth: Reject connection with the device which has same BD_ADDR
ERROR: that open brace { should be on the previous line
#144: FILE: net/bluetooth/hci_conn.c:1631:
+ if (!bacmp(&hdev->bdaddr, dst))
+ {
ERROR: that open brace { should be on the previous line #162: FILE: net/bluetooth/hci_event.c:3271:
+ if (!bacmp(&hdev->bdaddr, &ev->bdaddr))
+ {
WARNING: line length of 108 exceeds 100 columns
#164: FILE: net/bluetooth/hci_event.c:3273:
+ bt_dev_dbg(hdev, "Reject connection from the device with same BD_ADDR %pMR\n", &ev->bdaddr);
total: 2 errors, 1 warnings, 0 checks, 27 lines checked
NOTE: For some of the reported defects, checkpatch may be able to
mechanically convert to the typical style using --fix or --fix-inplace.
/github/workspace/src/src/13405332.patch has style problems, please review.
NOTE: Ignored message types: UNKNOWN_COMMIT_ID
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
##############################
Test: CheckSparse - WARNING
Desc: Run sparse tool with linux kernel
Output:net/bluetooth/hci_event.c: note: in included file (through include/net/bluetooth/hci_core.h):net/bluetooth/hci_event.c: note: in included file (through include/net/bluetooth/hci_core.h):
##############################
Test: CheckSmatch - WARNING
Desc: Run smatch tool with source
Output:net/bluetooth/hci_event.c: note: in included file (through include/net/bluetooth/hci_core.h):net/bluetooth/hci_event.c: note: in included file (through include/net/bluetooth/hci_core.h):
---
Regards,
Linux Bluetooth