Re: [RFC] IMA Log Snapshotting Design Proposal

Paul Moore
2023-08-30T22:21:22Z

On Wed, Aug 30, 2023 at 5:50 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> On Wed, 2023-08-30 at 16:47 -0400, Paul Moore wrote:
> > On Wed, Aug 30, 2023 at 4:25 PM Mimi Zohar <zohar@linux.ibm.com> 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, and your
continued avoidance is getting me increasingly annoyed.

--
paul-moore.com