From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A269309EF1; Wed, 3 Dec 2025 16:16:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764778611; cv=none; b=CsurItQr5BZSaKuMI9ArIocPicNqS/tUzhWL6APiCIMoTQfGCmYxF7bPkTf+e87Gs3zJOgqVGXVCMwmJP1Lkzsua1SNCMSAjL4o87OVD6vsu53dXD5q1eO+54366ueu/LWEPsUHiD0msIHT7BgqPMGxpIp15RmBe/rM07m8e63g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764778611; c=relaxed/simple; bh=zdCjY0rMo3r4w0x9Ix85JRNKUf+R04ZTdODUFuHZAhA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rXQmquEgKWBm/x6NgaCV+U3PK5ip04r2hOv/Pyjih7pviXXGYEIasdItkNBzpjXLr5qr9PsaSCH+pqqa48TYbRN49N1Cj9iyNjQWwONXsxmYPRU6GTCNeYnnPmo5b9AhlCVGpf1iqZ5Xvu6p76+j439Wv1lWlJrYxfL34mCW4S8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rpARif03; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rpARif03" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3727C4CEF5; Wed, 3 Dec 2025 16:16:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764778611; bh=zdCjY0rMo3r4w0x9Ix85JRNKUf+R04ZTdODUFuHZAhA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rpARif03jt1d5y1swHB0LFFP2McSnvlx1Co0ktcmC/VdyMR1n+J4FRPdV12EGSJNG WYOt1Zx1YFoIpIOONzn2MbbjE/Bj13SUEGb3zoTdKKYQ9bOYBru8lnWttk1V8+JIp3 a+x4pYH8ZFhqlIV1pVFw3EHckEPQmrzNCbOq9D5U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alex Lu , Max Chou , Luiz Augusto von Dentz , Nazar Kalashnikov Subject: [PATCH 5.15 387/392] Bluetooth: Add more enc key size check Date: Wed, 3 Dec 2025 16:28:57 +0100 Message-ID: <20251203152428.434741791@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251203152414.082328008@linuxfoundation.org> References: <20251203152414.082328008@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Lu [ Upstream commit 04a342cc49a8522e99c9b3346371c329d841dcd2 ] When we are slave role and receives l2cap conn req when encryption has started, we should check the enc key size to avoid KNOB attack or BLUFFS attack. >>From SIG recommendation, implementations are advised to reject service-level connections on an encrypted baseband link with key strengths below 7 octets. A simple and clear way to achieve this is to place the enc key size check in hci_cc_read_enc_key_size() The btmon log below shows the case that lacks enc key size check. > HCI Event: Connect Request (0x04) plen 10 Address: BB:22:33:44:55:99 (OUI BB-22-33) Class: 0x480104 Major class: Computer (desktop, notebook, PDA, organizers) Minor class: Desktop workstation Capturing (Scanner, Microphone) Telephony (Cordless telephony, Modem, Headset) Link type: ACL (0x01) < HCI Command: Accept Connection Request (0x01|0x0009) plen 7 Address: BB:22:33:44:55:99 (OUI BB-22-33) Role: Peripheral (0x01) > HCI Event: Command Status (0x0f) plen 4 Accept Connection Request (0x01|0x0009) ncmd 2 Status: Success (0x00) > HCI Event: Connect Complete (0x03) plen 11 Status: Success (0x00) Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33) Link type: ACL (0x01) Encryption: Disabled (0x00) ... > HCI Event: Encryption Change (0x08) plen 4 Status: Success (0x00) Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33) Encryption: Enabled with E0 (0x01) < HCI Command: Read Encryption Key Size (0x05|0x0008) plen 2 Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33) > HCI Event: Command Complete (0x0e) plen 7 Read Encryption Key Size (0x05|0x0008) ncmd 2 Status: Success (0x00) Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33) Key size: 6 // We should check the enc key size ... > ACL Data RX: Handle 1 flags 0x02 dlen 12 L2CAP: Connection Request (0x02) ident 3 len 4 PSM: 25 (0x0019) Source CID: 64 < ACL Data TX: Handle 1 flags 0x00 dlen 16 L2CAP: Connection Response (0x03) ident 3 len 8 Destination CID: 64 Source CID: 64 Result: Connection pending (0x0001) Status: Authorization pending (0x0002) > HCI Event: Number of Completed Packets (0x13) plen 5 Num handles: 1 Handle: 1 Address: BB:22:33:44:55:99 (OUI BB-22-33) Count: 1 #35: len 16 (25 Kb/s) Latency: 5 msec (2-7 msec ~4 msec) < ACL Data TX: Handle 1 flags 0x00 dlen 16 L2CAP: Connection Response (0x03) ident 3 len 8 Destination CID: 64 Source CID: 64 Result: Connection successful (0x0000) Status: No further information available (0x0000) Cc: stable@vger.kernel.org Signed-off-by: Alex Lu Signed-off-by: Max Chou Signed-off-by: Luiz Augusto von Dentz [ Nazar Kalashnikov: change status to rp_status due to function parameter conflict ] Signed-off-by: Nazar Kalashnikov Signed-off-by: Greg Kroah-Hartman --- Backport fix for CVE-2023-24023 net/bluetooth/hci_event.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -3136,6 +3136,7 @@ static void read_enc_key_size_complete(s const struct hci_rp_read_enc_key_size *rp; struct hci_conn *conn; u16 handle; + u8 rp_status; BT_DBG("%s status 0x%02x", hdev->name, status); @@ -3145,6 +3146,7 @@ static void read_enc_key_size_complete(s } rp = (void *)skb->data; + rp_status = rp->status; handle = le16_to_cpu(rp->handle); hci_dev_lock(hdev); @@ -3157,15 +3159,30 @@ static void read_enc_key_size_complete(s * secure approach is to then assume the key size is 0 to force a * disconnection. */ - if (rp->status) { + if (rp_status) { bt_dev_err(hdev, "failed to read key size for handle %u", handle); conn->enc_key_size = 0; } else { conn->enc_key_size = rp->key_size; + rp_status = 0; + + if (conn->enc_key_size < hdev->min_enc_key_size) { + /* As slave role, the conn->state has been set to + * BT_CONNECTED and l2cap conn req might not be received + * yet, at this moment the l2cap layer almost does + * nothing with the non-zero status. + * So we also clear encrypt related bits, and then the + * handler of l2cap conn req will get the right secure + * state at a later time. + */ + rp_status = HCI_ERROR_AUTH_FAILURE; + clear_bit(HCI_CONN_ENCRYPT, &conn->flags); + clear_bit(HCI_CONN_AES_CCM, &conn->flags); + } } - hci_encrypt_cfm(conn, 0); + hci_encrypt_cfm(conn, rp_status); unlock: hci_dev_unlock(hdev);