linux-kernel - Re: [PATCH v2] firmware_loader: use kernel credentials when reading firmware

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Message-ID: <YmgeSXJ9qWUI3J8/@bombadil.infradead.org>
Date:   Tue, 26 Apr 2022 09:31:05 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Thiébaud Weksteen <tweek@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jeffrey Vander Stoep <jeffv@...gle.com>,
        Saravana Kannan <saravanak@...gle.com>,
        Alistair Delva <adelva@...gle.com>,
        Adam Shih <adamshih@...gle.com>,
        SElinux list <selinux@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] firmware_loader: use kernel credentials when reading
 firmware

On Tue, Apr 26, 2022 at 02:18:59PM +1000, Thiébaud Weksteen wrote:
> > Can you elaborate on the last sentence? It's unclear how what you
> > describe is used exactly to allow driver to use direct filesystem
> > firmware loading.
> 
> I realize my use of the word "device" here was unfortunate. I meant devices as
> Android devices/systems. This may have contributed to the confusion.
> 
> Previously, Android systems were not setting up the firmware_class.path
> command line argument. It means that the userspace fallback was always
> kicking-in when a driver called request_firmware. This was handled by the
> ueventd process on Android, which is generally given access to all firmware
> files.
> 
> Now that more devices are setting up firmware_class.path, the call to
> request_firmware will end up using kernel_read_file_from_path_initns, which
> would have used the current process credentials.

That makes it crystal clear. This would be useful in the commit log.

> > And, given the feedback from Android it would seem this is a fix
> > which likely may be desirable to backport to some stable kernels?
> 
> Yes, that's right.

Especially in light of this.

  Luis