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=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 CF0CAC7618F for ; Mon, 15 Jul 2019 16:54:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B0E4A2080A for ; Mon, 15 Jul 2019 16:54:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731252AbfGOQyM (ORCPT ); Mon, 15 Jul 2019 12:54:12 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:33086 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729533AbfGOQyL (ORCPT ); Mon, 15 Jul 2019 12:54:11 -0400 Received: from LHREML713-CAH.china.huawei.com (unknown [172.18.7.106]) by Forcepoint Email with ESMTP id DF8A4F5A9A65B8C0C267; Mon, 15 Jul 2019 17:54:09 +0100 (IST) Received: from [10.220.96.108] (10.220.96.108) by smtpsuk.huawei.com (10.201.108.36) with Microsoft SMTP Server (TLS) id 14.3.408.0; Mon, 15 Jul 2019 17:54:04 +0100 Subject: Re: [PATCH v4 0/3] initramfs: add support for xattrs in the initial ram disk To: Rob Landley , , Arvind Sankar CC: Mimi Zohar , , , , , , , , , , , , , , , References: <20190523121803.21638-1-roberto.sassu@huawei.com> <541e9ea1-024f-5c22-0b58-f8692e6c1eb1@landley.net> <33cfb804-6a17-39f0-92b7-01d54e9c452d@huawei.com> <1561909199.3985.33.camel@linux.ibm.com> <45164486-782f-a442-e442-6f56f9299c66@huawei.com> <1561991485.4067.14.camel@linux.ibm.com> From: Roberto Sassu Message-ID: Date: Mon, 15 Jul 2019 18:54:12 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <1561991485.4067.14.camel@linux.ibm.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.220.96.108] X-CFilter-Loop: Reflected Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Rob, Peter, Arvind, did you have the chance to have a look at this version of the patch set? Thanks Roberto On 7/1/2019 4:31 PM, Mimi Zohar wrote: > On Mon, 2019-07-01 at 16:42 +0300, Roberto Sassu wrote: >> On 6/30/2019 6:39 PM, Mimi Zohar wrote: >>> On Wed, 2019-06-26 at 10:15 +0200, Roberto Sassu wrote: >>>> On 6/3/2019 8:32 PM, Rob Landley wrote: >>>>> On 6/3/19 4:31 AM, Roberto Sassu wrote: >>>>>>> This patch set aims at solving the following use case: appraise files from >>>>>>> the initial ram disk. To do that, IMA checks the signature/hash from the >>>>>>> security.ima xattr. Unfortunately, this use case cannot be implemented >>>>>>> currently, as the CPIO format does not support xattrs. >>>>>>> >>>>>>> This proposal consists in including file metadata as additional files named >>>>>>> METADATA!!!, for each file added to the ram disk. The CPIO parser in the >>>>>>> kernel recognizes these special files from the file name, and calls the >>>>>>> appropriate parser to add metadata to the previously extracted file. It has >>>>>>> been proposed to use bit 17:16 of the file mode as a way to recognize files >>>>>>> with metadata, but both the kernel and the cpio tool declare the file mode >>>>>>> as unsigned short. >>>>>> >>>>>> Any opinion on this patch set? >>>>>> >>>>>> Thanks >>>>>> >>>>>> Roberto >>>>> >>>>> Sorry, I've had the window open since you posted it but haven't gotten around to >>>>> it. I'll try to build it later today. >>>>> >>>>> It does look interesting, and I have no objections to the basic approach. I >>>>> should be able to add support to toybox cpio over a weekend once I've got the >>>>> kernel doing it to test against. >>>> >>>> Ok. >>>> >>>> Let me give some instructions so that people can test this patch set. >>>> >>>> To add xattrs to the ram disk embedded in the kernel it is sufficient >>>> to set CONFIG_INITRAMFS_FILE_METADATA="xattr" and >>>> CONFIG_INITRAMFS_SOURCE="" in the kernel configuration. >>>> >>>> To add xattrs to the external ram disk, it is necessary to patch cpio: >>>> >>>> https://github.com/euleros/cpio/commit/531cabc88e9ecdc3231fad6e4856869baa9a91ef >>>> (xattr-v1 branch) >>>> >>>> and dracut: >>>> >>>> https://github.com/euleros/dracut/commit/a2dee56ea80495c2c1871bc73186f7b00dc8bf3b >>>> (digest-lists branch) >>>> >>>> The same modification can be done for mkinitramfs (add '-e xattr' to the >>>> cpio command line). >>>> >>>> To simplify the test, it would be sufficient to replace only the cpio >>>> binary and the dracut script with the modified versions. For dracut, the >>>> patch should be applied to the local dracut (after it has been renamed >>>> to dracut.sh). >>>> >>>> Then, run: >>>> >>>> dracut -e xattr -I (add -f to overwrite the ram disk) >>>> >>>> Xattrs can be seen by stopping the boot process for example by adding >>>> rd.break to the kernel command line. >>> >>> A simple way of testing, without needing any changes other than the >>> kernel patches, is to save the dracut temporary directory by supplying >>> "--keep" on the dracut command line, calling >>> usr/gen_initramfs_list.sh, followed by usr/gen_init_cpio with the "-e >>> xattr" option. >> >> Alternatively, follow the instructions to create the embedded ram disk >> with xattrs, and use the existing external ram disk created with dracut >> to check if xattrs are created. > > True, but this alternative is for those who normally use dracut to > create an initramfs, but don't want to update cpio or dracut. > > Mimi > -- HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Li Peng, Li Jian, Shi Yanli