linux-kernel - Re: Fixing CVE-2017-15361

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Date:   Thu, 26 Oct 2017 19:02:37 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Michal Suchánek <msuchanek@...e.de>
Cc:     Peter Huewe <peterhuewe@....de>,
        Matthew Garrett <mjg59@...gle.com>,
        linux-integrity <linux-integrity@...r.kernel.org>,
        Kari Hiitola <kari@...aani.com>, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Alexander Steffen <Alexander.Steffen@...ineon.com>
Subject: Re: Fixing CVE-2017-15361

On Thu, Oct 26, 2017 at 04:57:48PM +0200, Michal Suchánek wrote:
> On Thu, 26 Oct 2017 16:06:02 +0200
> Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> wrote:
> 
> > On Thu, Oct 26, 2017 at 02:59:02PM +0200, Michal Suchánek wrote:
> > > It does not really matter. People ignore the messages unless looking
> > > for something specific as you already noticed. Warn seems adequate
> > > because the cipher is weaker than expected but not known to
> > > be compromised. People who care can look up the message. People who
> > > don't care will ignore it even if it's crit.  
> > 
> > Is it worth of trouble to do any driver changes then (open question to
> > everyone)? I'm not sure it is worth of trouble to add cruft to the
> > driver code for a warning that will likely be ignored anyway.
> 
> If the kernel can reliably detect the affected TPMs it saves the
> user the work of figuring out where the firmware revision is accessible
> on the running machine and what firmware revisions are affected.
> 
> Thanks
> 
> Michal

Just giving the warning does not require any kernel functionality. If
nothing proactive is required from the kernel I'd move the
responsibility to the user space. Nothing in the kernel is broken an
kernel cannot workaround the issue by ay means.

/Jarkko