Re: [PATCH v1.2 0/5] IMA: making i_readcount a first class inodecitizen (reposting)

[Linus Torvalds]

On Sun, Nov 21, 2010 at 5:18 AM, Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> wrote:
>
> IMA (and the proposed EVM/IMA-appraisal patches) detects file change
> based on i_version. When the file is closed, if the file has changed,
> IMA marks the file as needing to be re-measured. Of course this requires
> the filesystem to be mounted with iversion. Don't know if this helps.

If you only do this at close time, I see a _major_ security hole.

The attacker can just write to the file, and keep it open. Ta-daa,
everybody who reads it sees the new contents, but your IMA logic is
oblivious and thinks it doesn't need to be re-measured.

                            Linus
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