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=-15.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 A4B6DC55ABD for ; Mon, 9 Nov 2020 17:24:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 44D8720789 for ; Mon, 9 Nov 2020 17:24:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="e20YFcng" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731554AbgKIRYG (ORCPT ); Mon, 9 Nov 2020 12:24:06 -0500 Received: from linux.microsoft.com ([13.77.154.182]:38056 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730588AbgKIRYG (ORCPT ); Mon, 9 Nov 2020 12:24:06 -0500 Received: from [192.168.0.104] (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id 0418D20B4905; Mon, 9 Nov 2020 09:24:04 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 0418D20B4905 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1604942645; bh=ta06hzgZzpA5ollIFWxpN65xzXn96qZS7d0S0MEGpnE=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=e20YFcngAW2EheTQNcto50vE8IPR7U6bJ1KFsZZSgd8SV7QIB7x1pSLCf8jIuKGz3 9osm//coJGoMMv9BUBy4SCs06mVYnb4vDoHn2vf5s3mzq6bkfeRcg5Dwv/QLyS71+O 6NzLb842Vpdr3vNJtLvTrpCmn6hGwUiqrL4VPRG8= Subject: Re: [PATCH v5 6/7] IMA: add critical_data to the built-in policy rules To: Mimi Zohar , Tushar Sugandhi , stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.com, paul@paul-moore.com Cc: tyhicks@linux.microsoft.com, sashal@kernel.org, jmorris@namei.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com References: <20201101222626.6111-1-tusharsu@linux.microsoft.com> <20201101222626.6111-7-tusharsu@linux.microsoft.com> <7219f4404bc1bed6eb090b94363c283ec3266a17.camel@linux.ibm.com> From: Lakshmi Ramasubramanian Message-ID: <4c568853-1e26-0a7b-f83b-022622e46031@linux.microsoft.com> Date: Mon, 9 Nov 2020 09:24:04 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/8/20 7:46 AM, Mimi Zohar wrote: > Hi Lakshmi, > > On Fri, 2020-11-06 at 15:51 -0800, Lakshmi Ramasubramanian wrote: >> >>>>> diff --git a/security/integrity/ima/ima_policy.c >>>>> b/security/integrity/ima/ima_policy.c >>>>> index ec99e0bb6c6f..dc8fe969d3fe 100644 >>>>> --- a/security/integrity/ima/ima_policy.c >>>>> +++ b/security/integrity/ima/ima_policy.c >>>> >>>>> @@ -875,6 +884,29 @@ void __init ima_init_policy(void) >>>>> ARRAY_SIZE(default_appraise_rules), >>>>> IMA_DEFAULT_POLICY); >>>>> + if (ima_use_critical_data) { >>>>> + template = lookup_template_desc("ima-buf"); >>>>> + if (!template) { >>>>> + ret = -EINVAL; >>>>> + goto out; >>>>> + } >>>>> + >>>>> + ret = template_desc_init_fields(template->fmt, >>>>> + &(template->fields), >>>>> + &(template->num_fields)); >>>> >>>> The default IMA template when measuring buffer data is "ima_buf". Is >>>> there a reason for allocating and initializing it here and not >>>> deferring it until process_buffer_measurement()? >>>> >>> >>> You are right - good catch. >>> I will remove the above and validate. >>> >> >> process_buffer_measurement() allocates and initializes "ima-buf" >> template only when the parameter "func" is NONE. Currently, only >> ima_check_blacklist() passes NONE for func when calling >> process_buffer_measurement(). >> >> If "func" is anything other than NONE, ima_match_policy() picks >> the default IMA template if the IMA policy rule does not specify a template. >> >> We need to add "ima-buf" in the built-in policy for critical_data so >> that the default template is not used for buffer measurement. >> >> Please let me know if I am missing something. >> > > Let's explain a bit further what is happening and why. As you said > ima_get_action() returns the template format, which may be the default > IMA template or the specific IMA policy rule template format. This > works properly for both the arch specific and custom policies, but not > for builtin policies, because the policy rules may contain a rule > specific .template field. When the rules don't contain a rule > specific template field, they default to the IMA default template. In > the case of builtin policies, the policy rules cannot contain the > .template field. > > The default template field for process_buffer_measurement() should > always be "ima-buf", not the default IMA template format. Let's fix > this prior to this patch. > > Probably something like this: > - In addition to initializing the default IMA template, initialize the > "ima-buf" template. Maybe something similiar to > ima_template_desc_current(). > - Set the default in process_buffer_measurement() to "ima-buf", before > calling ima_get_action(). > - modify ima_match_policy() so that the default policy isn't reset when > already specified. > Sure Mimi - I will try this out and update. thanks, -lakshmi > > >>>> >>>>> + if (ret) >>>>> + goto out; >>>>> + >>>>> + critical_data_rules[0].template = template; >>>>> + add_rules(critical_data_rules, >>>>> + ARRAY_SIZE(critical_data_rules), >>>>> + IMA_DEFAULT_POLICY); >>>>> + } >>>>> + >>>>> +out: >>>>> + if (ret) >>>>> + pr_err("%s failed, result: %d\n", __func__, ret); >>>>> + >>>>> ima_update_policy_flag(); >>>>> } >>>> >>> >>