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=-5.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no 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 B7242C433E0 for ; Wed, 24 Mar 2021 20:50:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 90BE661A18 for ; Wed, 24 Mar 2021 20:50:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238206AbhCXUuH (ORCPT ); Wed, 24 Mar 2021 16:50:07 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42388 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238108AbhCXUtk (ORCPT ); Wed, 24 Mar 2021 16:49:40 -0400 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 12OKWpqh157879; Wed, 24 Mar 2021 16:49:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : subject : from : to : cc : date : in-reply-to : references : content-type : content-transfer-encoding : mime-version; s=pp1; bh=oSk4ZvpIFfpvGW9vz/hLhm3l5dMxtXS4oNfyPDLD3r8=; b=X9C83N0V6kwHaDns3tPOXthGbKVrxbHgyJjF4T8Oz1lzzyv0C8n0N0yOrfSmAGhvUytg ZMshhOamMXbkMAiZRw9ceA/zcNsbum0UBtI1OlCaLWrf+xF+HdpzSAQWSohskcFZedLs WlyyCAOkzPV5ThH+ku1bEIFXl9nnlmLE+qnSViMaTiJ+51kGyge3X8RRHFVhGefWQenG LhCYm33xF52xUJxKQkUwhVBpn1ur6HVotFQXa4LrOnOeD5wvwnB6uxhNPkGzHqe7UuN6 QGG8peL7VJLzWibEZ78gWlB91IJj+qR+2/CzO18IoCGRxnHsl46h/4bimUwy0BKHimQt jg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 37g865gaw0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Mar 2021 16:49:17 -0400 Received: from m0098417.ppops.net (m0098417.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 12OKXi6w161283; Wed, 24 Mar 2021 16:49:17 -0400 Received: from ppma06fra.de.ibm.com (48.49.7a9f.ip4.static.sl-reverse.com [159.122.73.72]) by mx0a-001b2d01.pphosted.com with ESMTP id 37g865gavk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Mar 2021 16:49:17 -0400 Received: from pps.filterd (ppma06fra.de.ibm.com [127.0.0.1]) by ppma06fra.de.ibm.com (8.16.0.43/8.16.0.43) with SMTP id 12OKnF15028449; Wed, 24 Mar 2021 20:49:15 GMT Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by ppma06fra.de.ibm.com with ESMTP id 37d9a62fn6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Mar 2021 20:49:15 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 12OKnCc942860938 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 24 Mar 2021 20:49:12 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BD3C7A404D; Wed, 24 Mar 2021 20:49:12 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 54DF0A4059; Wed, 24 Mar 2021 20:49:07 +0000 (GMT) Received: from li-f45666cc-3089-11b2-a85c-c57d1a57929f.ibm.com (unknown [9.163.11.141]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 24 Mar 2021 20:49:07 +0000 (GMT) Message-ID: Subject: Re: [PATCH v1 3/3] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys From: Mimi Zohar To: jejb@linux.ibm.com, Ahmad Fatoum , Horia =?UTF-8?Q?Geant=C4=83?= , Jonathan Corbet , David Howells , Jarkko Sakkinen Cc: "kernel@pengutronix.de" , James Morris , "Serge E. Hallyn" , Aymen Sghaier , Herbert Xu , "David S. Miller" , Udit Agarwal , Jan Luebbe , David Gstir , Franck Lenormand , Sumit Garg , "keyrings@vger.kernel.org" , "linux-crypto@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-integrity@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-security-module@vger.kernel.org" , Pascal Van Leeuwen Date: Wed, 24 Mar 2021 16:49:05 -0400 In-Reply-To: <9ba89168d8c4f1e3d6797a0b3713e152ac6388fd.camel@linux.ibm.com> References: <319e558e1bd19b80ad6447c167a2c3942bdafea2.1615914058.git-series.a.fatoum@pengutronix.de> <01e6e13d-2968-0aa5-c4c8-7458b7bde462@nxp.com> <45a9e159-2dcb-85bf-02bd-2993d50b5748@pengutronix.de> <9ba89168d8c4f1e3d6797a0b3713e152ac6388fd.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-14.el8) X-TM-AS-GCONF: 00 Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-03-24_13:2021-03-24,2021-03-24 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 suspectscore=0 phishscore=0 priorityscore=1501 malwarescore=0 mlxscore=0 clxscore=1011 spamscore=0 adultscore=0 lowpriorityscore=0 impostorscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103240150 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Wed, 2021-03-24 at 09:14 -0700, James Bottomley wrote: > On Tue, 2021-03-23 at 14:07 -0400, Mimi Zohar wrote: > > On Tue, 2021-03-23 at 17:35 +0100, Ahmad Fatoum wrote: > > > Hello Horia, > > > > > > On 21.03.21 21:48, Horia Geantă wrote: > > > > On 3/16/2021 7:02 PM, Ahmad Fatoum wrote: > > > > [...] > > > > > +struct trusted_key_ops caam_trusted_key_ops = { > > > > > + .migratable = 0, /* non-migratable */ > > > > > + .init = trusted_caam_init, > > > > > + .seal = trusted_caam_seal, > > > > > + .unseal = trusted_caam_unseal, > > > > > + .exit = trusted_caam_exit, > > > > > +}; > > > > caam has random number generation capabilities, so it's worth > > > > using that > > > > by implementing .get_random. > > > > > > If the CAAM HWRNG is already seeding the kernel RNG, why not use > > > the kernel's? > > > > > > Makes for less code duplication IMO. > > > > Using kernel RNG, in general, for trusted keys has been discussed > > before. Please refer to Dave Safford's detailed explanation for not > > using it [1]. > > > > [1] > > https://lore.kernel.org/linux-integrity/BCA04D5D9A3B764C9B7405BBA4D4A3C035F2A38B@ALPMBAPA12.e2k.ad.ge.com/ > > I still don't think relying on one source of randomness to be > cryptographically secure is a good idea. The fear of bugs in the > kernel entropy pool is reasonable, but since it's widely used they're > unlikely to persist very long. Studies have shown that some TPMs > (notably the chinese manufactured ones) have suspicious failures in > their RNGs: > > https://www.researchgate.net/publication/45934562_Benchmarking_the_True_Random_Number_Generator_of_TPM_Chips > > And most cryptograhpers recommend using a TPM for entropy mixing rather > than directly: > > https://blog.cryptographyengineering.com/category/rngs/ > > The TPMFail paper also shows that in spite of NIST certification > things can go wrong with a TPM: > > https://tpm.fail/ We already had a lengthy discussion on replacing the TPM RNG with the kernel RNG for trusted keys, when TEE was being introduced [2,3]. I'm not interested in re-hashing that discussion here. The only difference now is that CAAM is a new trust source. I suspect the same concerns/issues persist, but at least in this case using the kernel RNG would not be a regression. [2] Pascal Van Leeuwen on mixing different sources of entropy and certification - https://lore.kernel.org/linux-integrity/MN2PR20MB29732A856A40131A671F949FCA950@MN2PR20MB2973.namprd20.prod.outlook.com/ [3] Jarrko on "regression" and tpm_asym.c - https://lore.kernel.org/linux-integrity/20191014190033.GA15552@linux.intel.com/ Mimi