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SubjectRe: PING^7 (was Re: [PATCH v2 00/14] Corrections and customization of the SG_IO command whitelist (CVE-2012-4542))
On Sat, May 25, 2013 at 01:14:37PM +0200, Paolo Bonzini wrote:
> > Don't think we can. It'd be a behavior change clearly visible to
> > userland at this point.
>
> We can (and even for MMC) if it is a build-time configuration knob. It
> would satisfy those people who want the CVE fixed, as long as userspace
> gets some configurability.

I don't think that's a good idea. We can gradually try to phase it
out by triggering warning message if SG_IO commands are issued to !MMC
devices but I'm not sure that'd be worth the effort.

> > * Merge the patch to give out SG_IO access along with write access, so
> > the use cases which want to give out SG_IO access can do so
> > explicitly and be fully responsible for the device. This makes
> > sense to me. If one wants to be allowed to issue raw commands to
> > the hardware, one takes the full responsibility.
>
> That's not possible; it would make it impossible to do things like using
> a privileged helper to open the file and passing it back via SCM_RIGHTS
> to an unprivileged program (running as the user). This is the ptrace
> attack that you mentioned.

I have no idea what you're talking about. I'm describing the same
thing you implemented and posted.

--
tejun


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