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Fri, 14 May 2021 18:50:55 +0000 (GMT) Received: from demeter.local (unknown [9.160.6.19]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTPS; Fri, 14 May 2021 18:50:55 +0000 (GMT) Subject: Re: Security Working Group - Wednesday May 12 - results To: Michael Richardson , openbmc@lists.ozlabs.org References: <35156c27-e195-c238-1bb9-d20a30db3c63@linux.ibm.com> <8febdc9d-08bb-4094-9cad-7e6035c5bd71@linux.ibm.com> <4508.1620855321@localhost> From: Joseph Reynolds Message-ID: Date: Fri, 14 May 2021 13:50:54 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 In-Reply-To: <4508.1620855321@localhost> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-GUID: _3JCKf2kBSY2lW7L5nMDCZYXS8r93N_x X-Proofpoint-ORIG-GUID: _3JCKf2kBSY2lW7L5nMDCZYXS8r93N_x Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-05-14_08:2021-05-12, 2021-05-14 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 adultscore=0 mlxscore=0 lowpriorityscore=0 suspectscore=0 priorityscore=1501 mlxlogscore=999 clxscore=1011 spamscore=0 malwarescore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105140144 X-BeenThere: openbmc@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development list for OpenBMC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org Sender: "openbmc" On 5/12/21 4:35 PM, Michael Richardson wrote: > Joseph Reynolds wrote: > > 1. Security impacts of enabling kexec (load and optionally execute new > > kernel) in the BMC's production kernel.  How does this work and play > > with secure boot and with IMA? > > > 2. What are the security impacts of having the proc file system file > > /proc/sysrq-triggerwhich can cause kernel panics which can cause the > > BMC to terminate processing? > > > 3. In general, how can you (an operator or the BMC's host system) > > recover a BMC which has become unresponsive, for example, because its > > kernel processing has failed.  A design introduces using > > /proc/sysrq-triggertogether with a recovery kernel installed by kexec. > > This tussle between locking down the system against all intrusions, vs being > able to fix stuff when in trouble is a serious debate. > > (Based upon how easily random alien technology takes over the Enterprise, we > know which way Starfleet engineers went.) > > So I suggest that in most cases, the secure boot process should disable > kexec (and sysrq-trigger!), but that this should be an tunable attribute > under control of the secure boot process. > > For the majority of data center, business and home users of systems, the risk > of malware in the bootpath of the BMC exceeds the risk of BMC failures, and > the cost remediation (taking a machine out of commission when there is a BMC problem). > Having said that, there is a Right-to-Repair concern, and I really hope that > manufacturers will provide for a hardware jumper, and for installation of new > trust anchors. > > But, there is a variety of ways to do that from kernel cmdlines, to being able to > boot alternate kernels, and perhaps this could be punted down the road for > the operator that needs (#3). Perhaps, coming back to my (humour) above, it > will in fact be Mars Rover missions or Starlink satellites that need it, and > probably, they can afford to do that work. Michael, Thanks for the NASA, Elon Musk, and Star Trek references.  (I loved the Daleks in Star Wars!) I believe kexec and sysrq-trigger should remain disabled in the OpenBMC project defaults. And the IBM design cited attempts to balance security and usability. Although I understand there is work in the OCP security project and other places to recover a trust anchor, I don't see anything practical for OpenBMC to use. - Joseph IBM design: https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/42948 > > -- > ] Never tell me the odds! | ipv6 mesh networks [ > ] Michael Richardson, Sandelman Software Works | IoT architect [ > ] mcr@sandelman.ca http://www.sandelman.ca/ | ruby on rails [ >