linux-kernel - Re: [PATCH v3] ima: detect changes to the backing overlay file

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Date:   Wed, 25 Oct 2023 14:01:15 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Eric Snowberg <eric.snowberg@...cle.com>
Cc:     "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Raul Rangel <rrangel@...omium.org>,
        Amir Goldstein <amir73il@...il.com>
Subject: Re: [PATCH v3] ima: detect changes to the backing overlay file

On Wed, 2023-10-25 at 16:27 +0000, Eric Snowberg wrote:
> 
> > On Oct 25, 2023, at 8:39 AM, Mimi Zohar <zohar@...ux.ibm.com> wrote:
> > 
> > Commit 18b44bc5a672 ("ovl: Always reevaluate the file signature for
> > IMA") forced signature re-evaulation on every file access.
> > 
> > Instead of always re-evaluating the file's integrity, detect a change
> > to the backing file, by comparing the cached file metadata with the
> > backing file's metadata.  Verifying just the i_version has not changed
> > is insufficient.  In addition save and compare the i_ino and s_dev
> > as well.
> > 
> > Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
> 
> I ran the file integrity tests that originally uncovered the need for 
> "Commit 18b44bc5a672 ("ovl: Always reevaluate the file signature for 
> IMA”). When the backing file is changed, file integrity remains.  For that 
> part, feel free to add:
> 
> Tested-by: Eric Snowberg <eric.snowberg@...cle.com>

Thanks!

Mimi