Re: [dm-devel] [PATCH 1/1] dm: add message command to disallow device open

[Mikulas Patocka]

On Fri, 15 Jul 2022, Daniil Lunev wrote:

> Hi Mike,
> Thank you for your response. I should have probably added more context
> to the commit message that I specified in the cover letter. The idea is to
> prohibit access of all userspace, including the root. The main concern here
> is potential system applications' vulnerabilities that can trick the system to
> operate on non-intended files with elevated permissions. While those could
> also be exploited to get more access to the regular file systems, those firstly
> has to be useable by userspace for normal system operation (e.g. to store
> user data), secondly, never contain plain text secrets. Swap content is a
> different story - access to it can leak very sensitive information, which
> otherwise is never available as plaintext on any persistent media - e.g. raw
> user secrets, raw disk encryption keys etc, other security related tokens.
> Thus we propose a mechanism to enable such a lockdown after necessary
> configuration has been done to the device at boot time.
> --Daniil

If someone gains root, he can do anything on the system.

I'm quite skeptical about these attempts; protecting the system from the 
root user is never-ending whack-a-mole game.

Mikulas