From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 601E1C4332D for ; Wed, 27 Jan 2021 01:35:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 305FF2068D for ; Wed, 27 Jan 2021 01:35:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391903AbhA0BXL (ORCPT ); Tue, 26 Jan 2021 20:23:11 -0500 Received: from linux.microsoft.com ([13.77.154.182]:53948 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392754AbhAZTPn (ORCPT ); Tue, 26 Jan 2021 14:15:43 -0500 Received: from rapha-Virtual-Machine.mshome.net (unknown [131.107.160.57]) by linux.microsoft.com (Postfix) with ESMTPSA id A967C20B7192; Tue, 26 Jan 2021 11:15:00 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A967C20B7192 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1611688500; bh=3pedSW7ycGCkoC2khE7e44TNk6h2ZCycQXpy61AIp00=; h=From:To:Cc:Subject:Date:From; b=n7gmKKFThyhfdlV6QNQtEt+hoM+LQl95cEathr6VdOCHD7MAMN735j2Dw8fsuyWxU +9CDbV7zDrPbq+pjcEr4cNkNeZx4zcnn11lfYF2q2QltffFcxBkaA/MEm9ip2nyaQx NRdAP6/VOtdlWdlVmuaoLkFzf2f/5eOl5xiYeCyw= From: Raphael Gianotti To: zohar@linux.ibm.com Cc: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, tusharsu@linux.microsoft.com, nramas@linux.microsoft.com, tyhicks@linux.microsoft.com Subject: [PATCH v4] IMA: Measure kernel version in early boot Date: Tue, 26 Jan 2021 11:14:53 -0800 Message-Id: <20210126191453.3927-1-raphgi@linux.microsoft.com> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org The integrity of a kernel can be verified by the boot loader on cold boot, and during kexec, by the current running kernel, before it is loaded. However, it is still possible that the new kernel being loaded is older than the current kernel, and/or has known vulnerabilities. Therefore, it is imperative that an attestation service be able to verify the version of the kernel being loaded on the client, from cold boot and subsequent kexec system calls, ensuring that only kernels with versions known to be good are loaded. Measure the kernel version using ima_measure_critical_data() early on in the boot sequence, reducing the chances of known kernel vulnerabilities being exploited. With IMA being part of the kernel, this overall approach makes the measurement itself more trustworthy. To enable measuring the kernel version "ima_policy=critical_data" needs to be added to the kernel command line arguments. For example, BOOT_IMAGE=/boot/vmlinuz-5.11.0-rc3+ root=UUID=fd643309-a5d2-4ed3-b10d-3c579a5fab2f ro nomodeset ima_policy=critical_data If runtime measurement of the kernel version is ever needed, the following should be added to /etc/ima/ima-policy: measure func=CRITICAL_DATA label=kernel_info To extract the measured data after boot, the following command can be used: grep -m 1 "kernel_version" \ /sys/kernel/security/integrity/ima/ascii_runtime_measurements Sample output from the command above: 10 a8297d408e9d5155728b619761d0dd4cedf5ef5f ima-buf sha256:5660e19945be0119bc19cbbf8d9c33a09935ab5d30dad48aa11f879c67d70988 kernel_version 352e31312e302d7263332d31363138372d676564623634666537383234342d6469727479 The above hex-ascii string corresponds to the kernel version (e.g. xxd -r -p): 5.11.0-rc3-16187-gedb64fe78244-dirty Signed-off-by: Raphael Gianotti Signed-off-by: Mimi Zohar --- Change Log v4: - Updated patch description Change Log v3: - Updated critical data label as kernel_info in Documentation/ABI/testing/ima_policy - Moved the ima_measure_critical_data() call to ima_init() Change Log v2: - Changed the measurement to align with the latest version of ima_measure_critical_data(), without the need for queueing - Scoped the measurement to only measure the kernel version, found in UTS_RELEASE, instead of the entire linux_banner string This patch is based on commit e58bb688f2e4 "Merge branch 'measure-critical-data' into next-integrity" in "next-integrity-testing" branch Documentation/ABI/testing/ima_policy | 2 +- security/integrity/ima/ima_init.c | 5 +++++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 8365596cb42b..bc8e1cbe5e61 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -52,7 +52,7 @@ Description: template:= name of a defined IMA template type (eg, ima-ng). Only valid when action is "measure". pcr:= decimal value - label:= [selinux]|[data_label] + label:= [selinux]|[kernel_info]|[data_label] data_label:= a unique string used for grouping and limiting critical data. For example, "selinux" to measure critical data for SELinux. diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c index 4902fe7bd570..6e8742916d1d 100644 --- a/security/integrity/ima/ima_init.c +++ b/security/integrity/ima/ima_init.c @@ -15,6 +15,8 @@ #include #include #include +#include +#include #include "ima.h" @@ -147,5 +149,8 @@ int __init ima_init(void) ima_init_key_queue(); + ima_measure_critical_data("kernel_info", "kernel_version", + UTS_RELEASE, strlen(UTS_RELEASE), false); + return rc; } -- 2.28.0