On Sun, Jan 08, 2017 at 07:17:07PM +0100, bancfc@xxxxxxxxxxxxxxx wrote:
On 2016-12-27 04:05, bancfc@xxxxxxxxxxxxxxx wrote:Background: Canvas fingerprinting is a technique to track users based on their GPUs. https://en.wikipedia.org/wiki/Canvas_fingerprinting Someone did some testing and the good news is the fingerprint is common for all users of the same OS across all KVM users because it presents the same virtual GPU/drivers for everybody. What I need your help to find out is whether this holds for Virgil3D users that enable graphics acceleration. (I am running on Debian and the libvirt version in the repos is too old to have this included also
$ ./configure && make && make install # O:-)
I don't have multiple machines)
Oh, not even nested VMs won't hep here :(
To test this you need: To run plain FireFox on a virtualized distro (with GL acceleration enabled in libvirt) of your choice and visit https://browserleaks.com/canvas . Then repeat the same steps with that same distro (in a VM) on another physical machine and compare values. A good result is if you see the same numbers for both machines. That means the virtual device fingerprint is uniform for all virtual users.Bumping. I realized I post this in holiday season when it was easily missed.
Not only were even patches discussed during that time, but people will catch up on things after the break, don't worry.
Since CANVAS is about graphics drivers version the question can be simplified: Is the virtio-gpu driver version uniform across KVM versions?
I think the drivers and versions will not be the same nor different *all the time*. Based on what the method says, the main difference is done by font selection, hinting and antialiasing settings. I don't think that will be dependent on the graphics hardware. Although the hardware description might look the same. The details about that should probably be asked somewhere else than libvirt, e.g. whoever does virglrenderer or qemu or... I don't have another machine handy and my graphics guests are borked for some reason (and I spent a lot of time trying to fix those already), so I won't help much there. I tried it with some live media, but then realized it's not going to help. I'd have to try the same VM (not only distro), I guess.
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