On Wed, Jul 01, 2020 at 10:47:50AM +0200, Pavel Machek wrote: > Hi! > > > > We normally trust the hardware NOT to be malicious. (Because if hacker > > > has physical access to hardware and lot of resources, you lost). > > > > That is what we originally thought, however the world has changed and we > > need to be better about this, now that it is trivial to create a "bad" > > device. > > I'm not disagreeing. > > > > This is still true today, but maybe trusting USB devices is bad idea, > > > so drivers are being cleaned up. PCI drivers will be WORSE in this > > > regard. And you can't really protect against malicious CPU, and it is > > > very very hard to protect against malicous RAM (probably not practical > > > without explicit CPU support). > > > > > > Linux was designed with "don't let hackers near your hardware" threat > > > model in mind. > > > > Yes, it originally was designed that way, but again, the world has > > changed so we have to change with it. That is why USB has for a long > > time now, allowed you to not bind drivers to devices that you do not > > "trust", and that trust can be determined by userspace. That all came > > about thanks to the work done by the wireless USB spec people and kernel > > authors, which showed that maybe you just don't want to trust any device > > that comes within range of your system :) > > Again, not disagreeing; but note the scale here. > > It is mandatory to defend against malicious wireless USB devices. Turns out there are no more wireless USB devices in the world, and the code for that is gone from Linux :) > We probably should work on robustness against malicious USB devices. We are, and do have, that support today. > Malicious PCI-express devices are lot less of concern. Not really, they are a lot of concern to some people. Valid attacks are out there today, see the thunderbolt attacks that numerous people have done and published recently and for many years. > Defending against malicious CPU/RAM does not make much sense. That's what the spectre and rowhammer fixes have been for :) thanks, greg k-h
