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

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Message-ID: <485C9C57-ABF1-4618-81D1-345597A1B9FA@oracle.com>
Date:   Wed, 25 Oct 2023 16:27:52 +0000
From:   Eric Snowberg <eric.snowberg@...cle.com>
To:     Mimi Zohar <zohar@...ux.ibm.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 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>