linux-kernel - Re: [PATCH v9 04/23] securityfs: Extend securityfs with namespacing support

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Message-ID: <b811c99ee635704cf42cf35dbe9df15460df9c1f.camel@linux.ibm.com>
Date:   Mon, 31 Jan 2022 18:43:12 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>,
        Stefan Berger <stefanb@...ux.vnet.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,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Christian Brauner <brauner@...nel.org>
Subject: Re: [PATCH v9 04/23] securityfs: Extend securityfs with namespacing
 support

On Mon, 2022-01-31 at 17:28 -0500, Stefan Berger wrote:
> On 1/27/22 11:53, Mimi Zohar wrote:
> > On Tue, 2022-01-25 at 17:46 -0500, Stefan Berger wrote:
> >> From: Stefan Berger <stefanb@...ux.ibm.com>
> >>
> >> Enable multiple instances of securityfs by keying each instance with a
> >> pointer to the user namespace it belongs to.
> >>
> >> Since we do not need the pinning of the filesystem for the virtualization
> >> case, limit the usage of simple_pin_fs() and simpe_release_fs() to the
> >> case when the init_user_ns is active. This simplifies the cleanup for the
> >> virtualization case where usage of securityfs_remove() to free dentries
> >> is not needed anymore.
> > Could you add a sentence here explaining why securityfs_remove() isn't
> > needed in the virtualization case?
> 
> At this point the reason is that simple_pin_fs() is not used for the 
> virtualization case.
> 
> Maybe it should say: ... to free dentries is *therefore* not needed anymore.

Probably it's obvious, but I was looking for something along the lines
of, "The securityfs file or directory is automatically removed based on
reference count."

No need to update it.

thanks,

Mimi