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Wed, 30 Aug 2023 23:06:32 +0000 (GMT) Message-ID: <0835ea7fd96df23419431301dfbc0d190e6c36f4.camel@linux.ibm.com> Subject: Re: [RFC] IMA Log Snapshotting Design Proposal From: Mimi Zohar To: Paul Moore Cc: Sush Shringarputale , linux-integrity@vger.kernel.org, peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca, kgold@linux.ibm.com, bhe@redhat.com, vgoyal@redhat.com, dyoung@redhat.com, kexec@lists.infradead.org, jmorris@namei.org, serge@hallyn.com, code@tyhicks.com, nramas@linux.microsoft.com, linux-security-module@vger.kernel.org, AmirGoldstein , Tushar Sugandhi Date: Wed, 30 Aug 2023 19:06:32 -0400 In-Reply-To: References: <277db5491460d5fd607785f2bcc733de39022a35.camel@linux.ibm.com> <0e1511e8819b24ab8a34a7b15821f06eff688f29.camel@linux.ibm.com> <8bc0f024-fc12-cb32-7af0-e500948cc6db@linux.microsoft.com> <7e32afa2596b9d8cfdc275614575b2023cd1d673.camel@linux.ibm.com> <077249ac2bf2cb6d34347514e921720bb0f30b66.camel@linux.ibm.com> <930e517c724fac27f7a1a4165af51dbc37cce4a0.camel@linux.ibm.com> <2d800c3c0b6b4908843b490c36ef9df0cb4da134.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-22.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: VEMtDM6WuitrslPHoPoNyN3_CV9oF8Ff X-Proofpoint-ORIG-GUID: viWottO6RWAVJm23NJcvh6L2lmowyLP9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.957,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-08-30_18,2023-08-29_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 adultscore=0 impostorscore=0 spamscore=0 suspectscore=0 malwarescore=0 mlxlogscore=999 bulkscore=0 mlxscore=0 phishscore=0 clxscore=1015 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2308100000 definitions=main-2308300209 Precedence: bulk List-ID: On Wed, 2023-08-30 at 18:23 -0400, Paul Moore wrote: > On Wed, Aug 30, 2023 at 6:21 PM Paul Moore wrote: > > On Wed, Aug 30, 2023 at 5:50 PM Mimi Zohar wrote: > > > On Wed, 2023-08-30 at 16:47 -0400, Paul Moore wrote: > > > > On Wed, Aug 30, 2023 at 4:25 PM Mimi Zohar wrote: > > > > > Your initial question was "what happens if the file/filesystem becomes > > > > > inaccessible at some point and an attestation client attempts to read > > > > > the entire log?". For what reason would it be inaccessible? For the > > > > > original single tmpfs file, what would make it inaccessible? > > > > > > > > In your reply that I had responded to you had mentioned that the > > > > kernel was simply being passed a fd and taking ownership of it, the fd > > > > could either be a tmpfs backed file or some form of persistent storage > > > > as both were discussed in this thread. I imagine a tmpfs filesystem > > > > could still be forcibly unmounted, resulting in problems, but I can't > > > > say that for certain. However, there are definitely cases where a fd > > > > backed against an arbitrary filesystem could run into problems: > > > > storage device issues for local filesystems, networking issues for > > > > network filesystems, and good old fashioned user/admin intervention in > > > > both cases. > > > > > > "I imagine tmpfs filesystem could still be forcibly unmounted" sounds > > > like an attack. Not being able to verify the measurement list against a > > > quote is probably a good thing. > > > > Okay, can you answer the question for an arbitrary persistent > > filesystem? That was always the more important question, ... The original proposal, not mine, suggested using a tmpfs file. The idea of writing the measurements to a file on a persistent filesystem wasn't mine either. Sush/Tushar were pushing for writing to a persistent file(s). No argument from me that writing to a file on an arbitrary persistent filesystem is not a good idea. -- thanks, Mimi