[systemd-devel] WebUSB

[Dan Williams]

On Tue, 2017-01-10 at 18:33 +0100, Greg KH wrote:
> On Tue, Jan 10, 2017 at 06:23:13PM +0100, Lars Knudsen wrote:
> > 
> > 
> > On Jan 10, 2017 18:19, "Greg KH" <greg at kroah.com> wrote:
> > 
> >     On Tue, Jan 10, 2017 at 06:04:46PM +0100, Lars Knudsen wrote:
> >     > I figured that made most sense :)
> >     >
> >     > Still, it would be good if we could have a rule to not grab
> > the CDC
> >     interface
> >     > part if the device includes WebUSB functionality.
> > 
> >     What exactly do you mean by "grab"?
> > 
> > MM probing :)
> 
> Probe should be fine, right?  Are you really thinking that MM needs
> to
> go "oh look, a cdc device, let's go look at all of the raw interfaces
> to
> ensure it really isn't a webusb device as well before I touch it!"
> 
> That way lies madness...
> 
> What's wrong with touching it?  The kernel already did, why would
> userspace care?

And we're quite happy to keep blacklisting specific VID/PID combos we
know are not modems. Another possible solution is to greylist devices
that happen to have webusb descriptors, such that they won't get auto-
probed, but could be probed on-demand via D-Bus.  But I'd rather that
happen via udev rules than MM trying to walk USB device attributes and
parsing webusb descriptors.

Dan

> >     > The likelihood of a modem+WebUSB combo is so small that it
> > must fall
> >     > in the category where potential rare exotic devices combining
> > it must
> >     > be whitelisted and the rest be left alone.
> > 
> >     I think you misunderstand just how crazy firmware authors can
> > be.  I'm
> >     sure we will see those types of devices in the wild.
> > 
> > ...But realistically how many? Bothering 99.9% to support the
> > special case
> > seems less logical than just finding the 0.1% and whitelisting it
> > (if needed)
> 
> That's the joy of writing an operating system for all devices on the
> planet, those 0.1% can be a lot of devices :)
> 
> Anyway, I don't think there's much to do here just yet, let's wait
> and
> see just how bad these webusb devices end up looking like...
> 
> thanks,
> 
> greg k-h
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