From patchwork Fri Apr 29 11:26:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 12831857 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 71F76C433F5 for ; Fri, 29 Apr 2022 11:26:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358321AbiD2L3y (ORCPT ); Fri, 29 Apr 2022 07:29:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358313AbiD2L3w (ORCPT ); Fri, 29 Apr 2022 07:29:52 -0400 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EDCD649264; Fri, 29 Apr 2022 04:26:33 -0700 (PDT) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 23T8HK4Q025933; Fri, 29 Apr 2022 11:26:31 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=dhabbGXhdWEZKSomL5GlgkEUR4yGtHLfzEtnFb5cnto=; b=F8WSIGckqIpKWXuXajNlRkPHnuKuPZ1luIfIIvjle/sZn896LPRQOjv4A5Qpjj4Nubwg 42JdS9201qvxDMyAHHCszVkWm0oYiE8Ty8R2a+uIT6WfjVZa7I1L66i9Mfe0Bz2ZxyK0 SGoyFF5L1fXMkO5YJoTnFcThfzPJ/ZcB9R+YoFftWDZR+Lmw8uc6uL/KIp3GOrD+eas+ xh7otjOiB6Jq3hDCzmG2OLCdX9LeFQOU5+wr3pLbFmmDEClp2zOxgsnHeoR7Wl3omEI8 mIgdT1WkizbREGdTgNgGsvQvd5+GnPJoqwHc0/KnAjGd1Hqt48xExobJNesdq74Oxwdz fQ== Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3fqtqvtn2q-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 29 Apr 2022 11:26:31 +0000 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 23TBCmPA016335; Fri, 29 Apr 2022 11:26:29 GMT Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by ppma04ams.nl.ibm.com with ESMTP id 3fm9391055-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 29 Apr 2022 11:26:29 +0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 23TBQQQZ42139918 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 29 Apr 2022 11:26:26 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1452D11C050; Fri, 29 Apr 2022 11:26:26 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3E5A511C04A; Fri, 29 Apr 2022 11:26:25 +0000 (GMT) Received: from li-f45666cc-3089-11b2-a85c-c57d1a57929f.ibm.com.com (unknown [9.65.70.88]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 29 Apr 2022 11:26:25 +0000 (GMT) From: Mimi Zohar To: linux-integrity@vger.kernel.org Cc: Mimi Zohar , Eric Biggers , Stefan Berger , linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 7/7] fsverity: update the documentation Date: Fri, 29 Apr 2022 07:26:01 -0400 Message-Id: <20220429112601.1421947-8-zohar@linux.ibm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220429112601.1421947-1-zohar@linux.ibm.com> References: <20220429112601.1421947-1-zohar@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: TIcGhbkW5n5o72ztsMLT7cyPTxVcp1fl X-Proofpoint-ORIG-GUID: TIcGhbkW5n5o72ztsMLT7cyPTxVcp1fl X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-04-29_06,2022-04-28_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 spamscore=0 clxscore=1015 mlxscore=0 suspectscore=0 mlxlogscore=755 phishscore=0 malwarescore=0 adultscore=0 impostorscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2204290064 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org Update the fsverity documentation related to IMA signature support. Signed-off-by: Mimi Zohar Acked-by: Stefan Berger --- Documentation/filesystems/fsverity.rst | 35 +++++++++++++++++--------- 1 file changed, 23 insertions(+), 12 deletions(-) diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst index 8cc536d08f51..b7d42fd65e9d 100644 --- a/Documentation/filesystems/fsverity.rst +++ b/Documentation/filesystems/fsverity.rst @@ -70,12 +70,23 @@ must live on a read-write filesystem because they are independently updated and potentially user-installed, so dm-verity cannot be used. The base fs-verity feature is a hashing mechanism only; actually -authenticating the files is up to userspace. However, to meet some -users' needs, fs-verity optionally supports a simple signature -verification mechanism where users can configure the kernel to require -that all fs-verity files be signed by a key loaded into a keyring; see -`Built-in signature verification`_. Support for fs-verity file hashes -in IMA (Integrity Measurement Architecture) policies is also planned. +authenticating the files may be done by: + +* Userspace-only + +* Builtin signature verification + userspace policy + + fs-verity optionally supports a simple signature verification + mechanism where users can configure the kernel to require that + all fs-verity files be signed by a key loaded into a keyring; + see `Built-in signature verification`_. + +* Integrity Measurement Architecture (IMA) + + IMA supports including fs-verity file digests and signatures in the + IMA measurement list and verifying fs-verity based file signatures + stored as security.ima xattrs, based on policy. + User API ======== @@ -653,12 +664,12 @@ weren't already directly answered in other parts of this document. hashed and what to do with those hashes, such as log them, authenticate them, or add them to a measurement list. - IMA is planned to support the fs-verity hashing mechanism as an - alternative to doing full file hashes, for people who want the - performance and security benefits of the Merkle tree based hash. - But it doesn't make sense to force all uses of fs-verity to be - through IMA. As a standalone filesystem feature, fs-verity - already meets many users' needs, and it's testable like other + IMA supports the fs-verity hashing mechanism as an alternative + to full file hashes, for those who want the performance and + security benefits of the Merkle tree based hash. However, it + doesn't make sense to force all uses of fs-verity to be through + IMA. fs-verity already meets many users' needs even as a + standalone filesystem feature, and it's testable like other filesystem features e.g. with xfstests. :Q: Isn't fs-verity useless because the attacker can just modify the