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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E303AC5DF62 for ; Wed, 26 Jan 2022 02:28:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236392AbiAZC2L (ORCPT ); Tue, 25 Jan 2022 21:28:11 -0500 Received: from szxga01-in.huawei.com ([45.249.212.187]:35870 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236373AbiAZC2K (ORCPT ); Tue, 25 Jan 2022 21:28:10 -0500 Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Jk70Q1cHvzcckc; Wed, 26 Jan 2022 10:27:18 +0800 (CST) Received: from [10.67.110.173] (10.67.110.173) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 26 Jan 2022 10:28:07 +0800 Message-ID: <3933adf5-4e9d-6b22-2e46-55643c504f52@huawei.com> Date: Wed, 26 Jan 2022 10:28:07 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [RESEND][PATCH] Documentation: added order requirement for ima_hash= Content-Language: en-US To: Mimi Zohar , CC: , , , , , References: <20220125090237.120357-1-guozihua@huawei.com> <36b6058f2cdf6bead917c06ecc6e8769bb88130c.camel@linux.ibm.com> From: "Guozihua (Scott)" In-Reply-To: <36b6058f2cdf6bead917c06ecc6e8769bb88130c.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.110.173] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500024.china.huawei.com (7.185.36.203) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/1/26 9:07, Mimi Zohar wrote: > On Tue, 2022-01-25 at 17:02 +0800, GUO Zihua wrote: >> From: Guo Zihua >> >> Commandline parameter ima_hash= and ima_template= has order requirement >> for them to work correctly together. Namely ima_hash= must be >> specified after ima_template=, otherwise ima_template= will be ignored. >> >> The reason is that when handling ima_hash=, ima template would be set to >> the default value if it has not been initialized already, and that value >> cannot be changed afterwards by ima_template=. >> >> This patch adds this limitation to the documentation. >> >> Reviewed-by: Roberto Sassu >> Signed-off-by: Guo Zihua > > This issue should be limited to the original "ima" template format, > which only supports hash algorithms of 20 bytes or less. The "ima_ng" > template has been the default since larger digests and templates were > upstreamed back in Linux 3.13[1]. Do you really still have kernels > built with the original "ima" template? > > [1] Refer to commit 4286587dccd4 ("ima: add Kconfig default measurement > list template"). > > thanks, > > Mimi Hi Mimi, The issue is that if ima_hash is specified before ima_template, ima_template will not work. Built-in default only affects which template will be loaded eventually. For example, if the built-in default template is ima-ng and user would like to change it to ima-sig with sha512 by specifying "ima_hash=sha512 ima_template=ima-sig" in command line, the result will be ima-ng with sha512, not ima-sig with sha512. -- Best GUO Zihua > >> --- >> Documentation/admin-guide/kernel-parameters.txt | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index f5a27f067db9..1b5aa6ca65f8 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -1843,6 +1843,10 @@ >> The list of supported hash algorithms is defined >> in crypto/hash_info.h. >> >> + This parameter must be specified after ima_template=, >> + as it would set the default template and that cannot be >> + changed by ima_template= afterwards. >> + >> ima_policy= [IMA] >> The builtin policies to load during IMA setup. >> Format: "tcb | appraise_tcb | secure_boot | >> @@ -1879,6 +1883,9 @@ >> Formats: { "ima" | "ima-ng" | "ima-sig" } >> Default: "ima-ng" >> >> + This parameter must be specified before ima_hash=. >> + Please refer to ima_hash= for further explanation. >> + >> ima_template_fmt= >> [IMA] Define a custom template format. >> Format: { "field1|...|fieldN" } > > > .