linux-kernel - Re: [PATCH v10 10/27] ima: Move IMA securityfs files into ima

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Date:   Thu, 17 Feb 2022 09:44:40 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>,
        linux-integrity@...r.kernel.org
Cc:     serge@...lyn.com, christian.brauner@...ntu.com,
        containers@...ts.linux.dev, dmitry.kasatkin@...il.com,
        ebiederm@...ssion.com, krzysztof.struczynski@...wei.com,
        roberto.sassu@...wei.com, mpeters@...hat.com, lhinds@...hat.com,
        lsturman@...hat.com, puiterwi@...hat.com, jejb@...ux.ibm.com,
        jamjoom@...ibm.com, linux-kernel@...r.kernel.org,
        paul@...l-moore.com, rgb@...hat.com,
        linux-security-module@...r.kernel.org, jmorris@...ei.org,
        Christian Brauner <brauner@...nel.org>
Subject: Re: [PATCH v10 10/27] ima: Move IMA securityfs files into
 ima_namespace or onto stack

On Tue, 2022-02-01 at 15:37 -0500, Stefan Berger wrote:
> Earlier we simplified how dentry creation and deletion is manged in
> securityfs. This allows us to move IMA securityfs files from global
> variables directly into ima_fs_ns_init() itself. We can now rely on
> those dentries to be cleaned up when the securityfs instance is cleaned
> when the last reference to it is dropped.
> 
> Things are slightly different for the initial IMA namespace. In contrast
> to non-initial IMA namespaces it has pinning logic binding the lifetime
> of the securityfs superblock to created dentries. We need to keep this
> behavior to not regress userspace. Since IMA never removes most of the
> securityfs files the initial securityfs instance stays pinned. This also
> means even for the initial IMA namespace we don't need to keep
> references to these dentries anywhere.
> 
> The ima_policy file is the exception since IMA can end up removing it
> on systems that don't allow reading or extending the IMA custom policy.
> 
> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
> Acked-by: Christian Brauner <brauner@...nel.org>

Really nicely worded patch description.  Thanks!

Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>