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Mon, 2 Aug 2021 15:01:16 +0000 (GMT) Received: from li-f45666cc-3089-11b2-a85c-c57d1a57929f.ibm.com (unknown [9.160.118.203]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 2 Aug 2021 15:01:16 +0000 (GMT) Message-ID: <1efee8d7f62fb0e413f6e28d40af62610b8ce450.camel@linux.ibm.com> Subject: Re: [RFC][PATCH v2 06/12] diglim: Interfaces - digest_list_add, digest_list_del From: Mimi Zohar To: Roberto Sassu , "gregkh@linuxfoundation.org" , "mchehab+huawei@kernel.org" Cc: "linux-integrity@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Igor Stoppa Date: Mon, 02 Aug 2021 11:01:15 -0400 In-Reply-To: <96c7cd3d19254e84a6cb45b2a940e944@huawei.com> References: <20210726163700.2092768-1-roberto.sassu@huawei.com> <20210726163700.2092768-7-roberto.sassu@huawei.com> <1ef95096bee13578b3f906dd9f708c6af9d6ff18.camel@linux.ibm.com> <555bf01bee4b4ea7a9bee658366d535a@huawei.com> <2c731f07bd08f01f2a3e032814bc65ae9a8494ad.camel@linux.ibm.com> <96c7cd3d19254e84a6cb45b2a940e944@huawei.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.28.5 (3.28.5-16.el8) X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ZQwL0SeAMMVVukqfkoWNXexSkUKdmvJ7 X-Proofpoint-GUID: ZQwL0SeAMMVVukqfkoWNXexSkUKdmvJ7 Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-02_05:2021-08-02,2021-08-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 spamscore=0 bulkscore=0 adultscore=0 mlxlogscore=999 lowpriorityscore=0 clxscore=1011 impostorscore=0 malwarescore=0 phishscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108020094 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Mon, 2021-08-02 at 08:14 +0000, Roberto Sassu wrote: > > From: Roberto Sassu [mailto:roberto.sassu@huawei.com] > > Sent: Friday, July 30, 2021 4:25 PM > > > From: Mimi Zohar [mailto:zohar@linux.ibm.com] > > > Sent: Friday, July 30, 2021 4:03 PM > > > Hi Roberto, > > > > > > On Fri, 2021-07-30 at 13:16 +0000, Roberto Sassu wrote: > > > > > From: Mimi Zohar [mailto:zohar@linux.ibm.com] > > > > > Sent: Friday, July 30, 2021 2:40 PM > > > > > > > > "critical data", in this context, should probably be used for verifying > > > > > the in memory file digests and other state information haven't been > > > > > compromised. > > > > > > > > Actually, this is what we are doing currently. To keep the > > > > implementation simple, once the file or the buffer are uploaded > > > > to the kernel, they will not be modified, just accessed through > > > > the indexes. > > > > > > My main concern about digest lists is their integrity, from loading the > > > digest lists to their being stored in memory. A while back, there was > > > some work on defining a write once memory allocator. I don't recall > > > whatever happened to it. This would be a perfect usecase for that > > > memory allocator. > > > > Adding Igor in CC. > > > > Regarding loading, everything uploaded to the kernel is carefully > > evaluated. This should not be a concern. Regarding making them > > read-only, probably if you can subvert digest lists you can also > > remove the read-only protection (unless you use an hypervisor). > > I briefly talked with Igor. He also agreed with that, and added that > it could make it more difficult for an attacker to also disable the > protection. However, he is not planning to submit an update soon, > so I wouldn't consider this an option for now. Hi Roberto, Greg, As long as others understand and agree to the risk, the IMA details can be worked out. thanks, Mimi