linux-kernel - Re: [PATCH 05/38] Annotate hardware config module parameters in drivers/char/

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Message-ID: <20170408152323.GB7879@kroah.com>
Date:   Sat, 8 Apr 2017 17:23:23 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-kernel@...r.kernel.org, gnomes@...rguk.ukuu.org.uk,
        Arnd Bergmann <arnd@...db.de>,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org
Subject: Re: [PATCH 05/38] Annotate hardware config module parameters in
 drivers/char/

On Wed, Apr 05, 2017 at 05:57:30PM +0100, David Howells wrote:
> When the kernel is running in secure boot mode, we lock down the kernel to
> prevent userspace from modifying the running kernel image.  Whilst this
> includes prohibiting access to things like /dev/mem, it must also prevent
> access by means of configuring driver modules in such a way as to cause a
> device to access or modify the kernel image.
> 
> To this end, annotate module_param* statements that refer to hardware
> configuration and indicate for future reference what type of parameter they
> specify.  The parameter parser in the core sees this information and can
> skip such parameters with an error message if the kernel is locked down.
> The module initialisation then runs as normal, but just sees whatever the
> default values for those parameters is.
> 
> Note that we do still need to do the module initialisation because some
> drivers have viable defaults set in case parameters aren't specified and
> some drivers support automatic configuration (e.g. PNP or PCI) in addition
> to manually coded parameters.
> 
> This patch annotates drivers in drivers/char/.
> 
> Suggested-by: Alan Cox <gnomes@...rguk.ukuu.org.uk>
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: Arnd Bergmann <arnd@...db.de>
> cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>