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=-19.0 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,SIGNED_OFF_BY,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 51445C5517A for ; Fri, 23 Oct 2020 22:55:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F116A2168B for ; Fri, 23 Oct 2020 22:54:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="s6tiEEKr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758400AbgJWWy5 (ORCPT ); Fri, 23 Oct 2020 18:54:57 -0400 Received: from linux.microsoft.com ([13.77.154.182]:35832 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758396AbgJWWy4 (ORCPT ); Fri, 23 Oct 2020 18:54:56 -0400 Received: from [192.168.86.21] (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id 1DA2020B4905; Fri, 23 Oct 2020 15:54:55 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 1DA2020B4905 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1603493695; bh=YGbAk5ZPXKS3MwP2MCJgwylXpPWtw4VBI3P7eYMsasE=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=s6tiEEKrsgrcNdDHkHFy1PWBspDVW/Y/1tk/hV4xn8q1r2paxanTHW5GdrRUAhYri YE8qrkSUe2ntdDnjt/3egpgUPwmyVtdcNSLTmaUskpAyc41w7fnauhNrq1INwTZ/ey Rl+Dh3T26UOBLDK3UQYnKavKO+J8KBFeOShs02I0= Subject: Re: [PATCH v4 5/6] IMA: add hook to measure critical data from kernel components To: Mimi Zohar , stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.com Cc: tyhicks@linux.microsoft.com, sashal@kernel.org, jmorris@namei.org, nramas@linux.microsoft.com, 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: <20200923192011.5293-1-tusharsu@linux.microsoft.com> <20200923192011.5293-6-tusharsu@linux.microsoft.com> From: Tushar Sugandhi Message-ID: <016d20e1-bb8f-f1f5-c69b-6fd811126e0c@linux.microsoft.com> Date: Fri, 23 Oct 2020 15:54:54 -0700 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=UTF-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: On 2020-10-22 3:35 p.m., Mimi Zohar wrote: > Hi Tushar, > > On Wed, 2020-09-23 at 12:20 -0700, Tushar Sugandhi wrote: >> Currently, IMA does not provide a generic function for kernel components >> to measure their data. A generic function provided by IMA would >> enable various parts of the kernel with easier and faster on-boarding to >> use IMA infrastructure, would avoid code duplication, and consistent >> usage of IMA policy option "data_sources:=" across the kernel. >> >> Add a new IMA func CRITICAL_DATA and a corresponding IMA hook >> ima_measure_critical_data() to support measuring various critical kernel >> components. Limit the measurement to the components that are specified >> in the IMA policy - CRITICAL_DATA+data_sources. >> >> Signed-off-by: Tushar Sugandhi > > Normally the new LSM or IMA hook is defined before defining a method of > constraining that hook. Please drop 2/6 (IMA: conditionally allow > empty rule data) and reverse the order of 4/6 and 5/6. That will > allow each patch to update the Documentation appropriately, making the > change self contained. > Sure. I will drop 2/6, and reverse the order of 4/6 and 5/6. >> --- >> Documentation/ABI/testing/ima_policy | 8 ++++++- >> include/linux/ima.h | 8 +++++++ >> security/integrity/ima/ima.h | 1 + >> security/integrity/ima/ima_api.c | 2 +- >> security/integrity/ima/ima_main.c | 26 +++++++++++++++++++++ >> security/integrity/ima/ima_policy.c | 34 ++++++++++++++++++++++++---- >> 6 files changed, 72 insertions(+), 7 deletions(-) >> >> diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy >> index a81cf79fb255..d33bb51309fc 100644 >> --- a/Documentation/ABI/testing/ima_policy >> +++ b/Documentation/ABI/testing/ima_policy >> @@ -29,7 +29,7 @@ Description: >> base: func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK] >> [FIRMWARE_CHECK] >> [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] >> - [KEXEC_CMDLINE] [KEY_CHECK] >> + [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA] >> mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] >> [[^]MAY_EXEC] >> fsmagic:= hex value >> @@ -51,6 +51,8 @@ Description: >> data_sources:= list of kernel components >> (eg, selinux|apparmor|dm-crypt) that contain data critical >> to the security of the kernel. >> + Only valid when action is "measure" and func is >> + CRITICAL_DATA. >> >> default policy: >> # PROC_SUPER_MAGIC >> @@ -128,3 +130,7 @@ Description: >> keys added to .builtin_trusted_keys or .ima keyring: >> >> measure func=KEY_CHECK keyrings=.builtin_trusted_keys|.ima >> + >> + Example of measure rule using CRITICAL_DATA to measure critical data >> + >> + measure func=CRITICAL_DATA data_sources=selinux|apparmor|dm-crypt > > > As data sources are added, the documentation example should be updated > to reflect the new source. Please do not include examples that don't > yet exist. > Makes sense. Will do. > >> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c >> index 6888fc372abf..d55896f28790 100644 >> --- a/security/integrity/ima/ima_main.c >> +++ b/security/integrity/ima/ima_main.c >> @@ -867,6 +867,32 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) >> fdput(f); >> } >> >> +/** >> + * ima_measure_critical_data - measure critical data >> + * @event_name: name for the given data >> + * @event_data_source: name of the event data source >> + * @buf: pointer to buffer containing data to measure >> + * @buf_len: length of buffer(in bytes) >> + * @measure_buf_hash: if set to true - will measure hash of the buf, >> + * instead of buf >> + * >> + * Buffers can only be measured, not appraised. >> + */ > > Perhaps the reason for defining both the event_name and > event_data_source will become clearer with an example. At this point I > can only guess as to why both are needed (e.g. perhaps a data source > defines multiple events). > Yes. Precisely. For example, in “dm-crypt” case: the data source is “dm-crypt” and possible events are “add_target”, “post_suspend”, "resume" etc. I will add a more detailed hook description as you suggested below, and explain this point in it. > While "Buffers can only be measured, not appraised" is true, it was cut > & pasted from ima_kexec_cmdline. Measuring the kexec boot cmdline is > self describing. Here, a larger, more detailed IMA hook description > would be appropriate. Will add. Thanks Mimi. > > thanks, > > Mimi >