Re: [libvirt] libvirt mdev migration, mdevctl integration

On Tue, Dec 10, 2019 at 11:24:44AM +0100, Cornelia Huck wrote: > On Tue, 10 Dec 2019 10:09:34 +0000 > Daniel P. Berrangé <berrange(a)redhat.com&gt; wrote: > > > On Mon, Dec 09, 2019 at 02:23:38PM -0600, Jonathon Jongsma wrote: > > > mdevctl also supports assigning arbitrary sysfs attributes to a device. > > > These attributes have an explicit ordering and are written to sysfs in > > > the specified order when a device is started. This might be the only > > > thing that doesn't fit into the current xml format. > > Not sure how much the 'explicit ordering' is actually required by the > devices currently supporting this. It's probably a good idea to keep > this, though, as future device types might end up having such a > requirement. > > > Well we need to define a schema, but there will need to be some kind > > of validation added because. AFAICT, mdevctl does no validation, so a > > plain passthrough of this allows arbitrary writing of files anywhere > > on the host given a suitable malicious attribute name. > > Uh, we really should do something about that in mdevctl as well. Writes > outside the sysfs hierarchy should not be allowed. I'm pretty worried about overall safety/reliability of the mdevctrl tool in general. Given that it is written in shell, it is really hard to ensure that it isn't vulnerable to any shell quoting / meta character flaws, whether from malicious or accidental data input.