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Message-Id: <20201015074333.445510-2-hegtvedt@cisco.com>
Date: Thu, 15 Oct 2020 09:43:33 +0200
From: Hans-Christian Noren Egtvedt <hegtvedt@...co.com>
To: linux-kernel@...r.kernel.org
Cc: gregkh@...uxfoundation.org,
Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
Marcel Holtmann <marcel@...tmann.org>
Subject: [PATCH v4.4/bluetooth 2/2] Bluetooth: Disconnect if E0 is used for Level 4
From: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>
E0 is not allowed with Level 4:
BLUETOOTH CORE SPECIFICATION Version 5.2 | Vol 3, Part C page 1319:
'128-bit equivalent strength for link and encryption keys
required using FIPS approved algorithms (E0 not allowed,
SAFER+ not allowed, and P-192 not allowed; encryption key
not shortened'
SC enabled:
> HCI Event: Read Remote Extended Features (0x23) plen 13
Status: Success (0x00)
Handle: 256
Page: 1/2
Features: 0x0b 0x00 0x00 0x00 0x00 0x00 0x00 0x00
Secure Simple Pairing (Host Support)
LE Supported (Host)
Secure Connections (Host Support)
> HCI Event: Encryption Change (0x08) plen 4
Status: Success (0x00)
Handle: 256
Encryption: Enabled with AES-CCM (0x02)
SC disabled:
> HCI Event: Read Remote Extended Features (0x23) plen 13
Status: Success (0x00)
Handle: 256
Page: 1/2
Features: 0x03 0x00 0x00 0x00 0x00 0x00 0x00 0x00
Secure Simple Pairing (Host Support)
LE Supported (Host)
> HCI Event: Encryption Change (0x08) plen 4
Status: Success (0x00)
Handle: 256
Encryption: Enabled with E0 (0x01)
[May 8 20:23] Bluetooth: hci0: Invalid security: expect AES but E0 was used
< HCI Command: Disconnect (0x01|0x0006) plen 3
Handle: 256
Reason: Authentication Failure (0x05)
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>
Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
(cherry picked from commit 8746f135bb01872ff412d408ea1aa9ebd328c1f5)
(cherry picked from commit f263237a1709a6dbf1dc9945187f1e64c53a4b73)
---
AFAICT, fixing CVE 2020-10135 Bluetooth impersonation attacks have been
left out for the 4.4 stable kernel. I cherry picked what I assume are
the appropriate two patches missing from the 4.9 stable kernel. Please
add them to upcoming 4.4 stable releases.
include/net/bluetooth/hci_core.h | 10 ++++++----
net/bluetooth/hci_conn.c | 17 +++++++++++++++++
net/bluetooth/hci_event.c | 20 ++++++++------------
3 files changed, 31 insertions(+), 16 deletions(-)
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 0269a772bfe1..d07730be8d5a 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1256,11 +1256,13 @@ static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
else
encrypt = 0x01;
- if (conn->sec_level == BT_SECURITY_SDP)
- conn->sec_level = BT_SECURITY_LOW;
+ if (!status) {
+ if (conn->sec_level == BT_SECURITY_SDP)
+ conn->sec_level = BT_SECURITY_LOW;
- if (conn->pending_sec_level > conn->sec_level)
- conn->sec_level = conn->pending_sec_level;
+ if (conn->pending_sec_level > conn->sec_level)
+ conn->sec_level = conn->pending_sec_level;
+ }
mutex_lock(&hci_cb_list_lock);
list_for_each_entry(cb, &hci_cb_list, list) {
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 2ff5950e9712..2567249b5bce 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1175,6 +1175,23 @@ int hci_conn_check_link_mode(struct hci_conn *conn)
return 0;
}
+ /* AES encryption is required for Level 4:
+ *
+ * BLUETOOTH CORE SPECIFICATION Version 5.2 | Vol 3, Part C
+ * page 1319:
+ *
+ * 128-bit equivalent strength for link and encryption keys
+ * required using FIPS approved algorithms (E0 not allowed,
+ * SAFER+ not allowed, and P-192 not allowed; encryption key
+ * not shortened)
+ */
+ if (conn->sec_level == BT_SECURITY_FIPS &&
+ !test_bit(HCI_CONN_AES_CCM, &conn->flags)) {
+ bt_dev_err(conn->hdev,
+ "Invalid security: Missing AES-CCM usage");
+ return 0;
+ }
+
if (hci_conn_ssp_enabled(conn) &&
!test_bit(HCI_CONN_ENCRYPT, &conn->flags))
return 0;
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index bb9c13506bca..f0e6cce921d8 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -2612,24 +2612,20 @@ static void hci_encrypt_change_evt(struct hci_dev *hdev, struct sk_buff *skb)
clear_bit(HCI_CONN_ENCRYPT_PEND, &conn->flags);
+ /* Check link security requirements are met */
+ if (!hci_conn_check_link_mode(conn))
+ ev->status = HCI_ERROR_AUTH_FAILURE;
+
if (ev->status && conn->state == BT_CONNECTED) {
+ /* Notify upper layers so they can cleanup before
+ * disconnecting.
+ */
+ hci_encrypt_cfm(conn, ev->status);
hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE);
hci_conn_drop(conn);
goto unlock;
}
- /* In Secure Connections Only mode, do not allow any connections
- * that are not encrypted with AES-CCM using a P-256 authenticated
- * combination key.
- */
- if (hci_dev_test_flag(hdev, HCI_SC_ONLY) &&
- (!test_bit(HCI_CONN_AES_CCM, &conn->flags) ||
- conn->key_type != HCI_LK_AUTH_COMBINATION_P256)) {
- hci_connect_cfm(conn, HCI_ERROR_AUTH_FAILURE);
- hci_conn_drop(conn);
- goto unlock;
- }
-
/* Try reading the encryption key size for encrypted ACL links */
if (!ev->status && ev->encrypt && conn->type == ACL_LINK) {
struct hci_cp_read_enc_key_size cp;
--
2.27.0
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