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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 3 Oct 2019 23:08:14 +0100 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 x93M8EWs54919378 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 3 Oct 2019 22:08:14 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E8611A4051; Thu, 3 Oct 2019 22:08:13 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 64297A4040; Thu, 3 Oct 2019 22:08:12 +0000 (GMT) Received: from dhcp-9-31-103-196.watson.ibm.com (unknown [9.31.103.196]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 3 Oct 2019 22:08:12 +0000 (GMT) Subject: Re: [PATCH] KEYS: asym_tpm: Switch to get_random_bytes() From: Mimi Zohar To: Jarkko Sakkinen Cc: David Safford , linux-integrity@vger.kernel.org, stable@vger.kernel.org, David Howells , Herbert Xu , "David S. Miller" , "open list:ASYMMETRIC KEYS" , "open list:CRYPTO API" , open list Date: Thu, 03 Oct 2019 18:08:11 -0400 In-Reply-To: <20191003215743.GB30511@linux.intel.com> References: <20190926171601.30404-1-jarkko.sakkinen@linux.intel.com> <1570024819.4999.119.camel@linux.ibm.com> <20191003114119.GF8933@linux.intel.com> <1570107752.4421.183.camel@linux.ibm.com> <20191003175854.GB19679@linux.intel.com> <1570128827.5046.19.camel@linux.ibm.com> <20191003215125.GA30511@linux.intel.com> <20191003215743.GB30511@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 (3.20.5-1.fc24) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19100322-0016-0000-0000-000002B3CD22 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19100322-0017-0000-0000-00003314D99D Message-Id: <1570140491.5046.33.camel@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-10-03_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=3 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=679 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910030179 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Fri, 2019-10-04 at 00:57 +0300, Jarkko Sakkinen wrote: > On Fri, Oct 04, 2019 at 12:51:25AM +0300, Jarkko Sakkinen wrote: > > On Thu, Oct 03, 2019 at 02:53:47PM -0400, Mimi Zohar wrote: > > > [Cc'ing David Safford] > > > > > > On Thu, 2019-10-03 at 20:58 +0300, Jarkko Sakkinen wrote: > > > > On Thu, Oct 03, 2019 at 09:02:32AM -0400, Mimi Zohar wrote: > > > > > On Thu, 2019-10-03 at 14:41 +0300, Jarkko Sakkinen wrote: > > > > > > On Wed, Oct 02, 2019 at 10:00:19AM -0400, Mimi Zohar wrote: > > > > > > > On Thu, 2019-09-26 at 20:16 +0300, Jarkko Sakkinen wrote: > > > > > > > > Only the kernel random pool should be used for generating random numbers. > > > > > > > > TPM contributes to that pool among the other sources of entropy. In here it > > > > > > > > is not, agreed, absolutely critical because TPM is what is trusted anyway > > > > > > > > but in order to remove tpm_get_random() we need to first remove all the > > > > > > > > call sites. > > > > > > > > > > > > > > At what point during boot is the kernel random pool available?  Does > > > > > > > this imply that you're planning on changing trusted keys as well? > > > > > > > > > > > > Well trusted keys *must* be changed to use it. It is not a choice > > > > > > because using a proprietary random number generator instead of defacto > > > > > > one in the kernel can be categorized as a *regression*. > > > > > > > > > > I really don't see how using the TPM random number for TPM trusted > > > > > keys would be considered a regression.  That by definition is a > > > > > trusted key.  If anything, changing what is currently being done would > > > > > be the regression.  > > > > > > > > It is really not a TPM trusted key. It trusted key that gets sealed with > > > > the TPM. The key itself is used in clear by kernel. The random number > > > > generator exists in the kernel to for a reason. > > > > > > > > It is without doubt a regression. > > > > > > You're misusing the term "regression" here.  A regression is something > > > that previously worked and has stopped working.  In this case, trusted > > > keys has always been based on the TPM random number generator.  Before > > > changing this, there needs to be some guarantees that the kernel > > > random number generator has a pool of random numbers early, on all > > > systems including embedded devices, not just servers. > > > > I'm not using the term regression incorrectly here. Wrong function > > was used to generate random numbers for the payload here. It is an > > obvious bug. > > At the time when trusted keys was introduced I'd say that it was a wrong > design decision and badly implemented code. But you are right in that as > far that code is considered it would unfair to speak of a regression. > > asym-tpm.c on the other hand this is fresh new code. There has been > *countless* of discussions over the years that random numbers should > come from multiple sources of entropy. There is no other categorization > than a bug for the tpm_get_random() there. This week's LWN article on "5.4 Merge window, part 2" discusses "boot- time entropy".  This article couldn't have been more perfectly timed. Mimi