[Veserv]

Cool, show me a LPE in a seL4 deployment. Do you believe that is easier or harder than finding a KVM escape?

Since you are varying the security basis, implementation, and operational model simultaneously when you are comparing KVM to Linux to argue that the security basis is the important factor, I get to as well. Except mine is actually more fair because the design of a seL4-based system is actually much more similar to the design of a multi-tenant KVM-based system than the design of the KVM-based system is to the design of a Linux user environment.

[tptacek]

Amusingly, this is the 2nd time you've tried to argue with me about this Theo post. Last time, you yourself brought it up as a model of a good security argument.

https://news.ycombinator.com/item?id=41071954

Rather than replicating my response then, I'll just incorporate that link into my point.

I ported L4 to my ARM NUC a couple weeks ago. L4 is great. Of course, L4 is also principally a platform for virtualization, so it's a pretty odd bit of evidence to try to bring up. Where have you personally been using L4?

[Veserv]

Yes, you do enjoy evading the argument. You continuously point at implementation and operational model differences as proof that virtualization is the key factor. Theo's argument is literally that virtualization versus non-virtualization is irrelevant compared to implementation and operational model deficiencys. If you make garbage implementations and operational models, then you get garbage virtualization. If you have a good implementation and operational model then you do not need virtualization for "security".

As independent evidence for this point, virtualization is not the basis of security/isolation in seL4. You have isolation without any virtual machines. Virtual machines are just a feature on top that can leverage the existing isolation functionality to also provide isolated virtual machines. Of course, a secure deployment then requires you to leverage this foundation with a good operational model and system design since you can always make a insecure system even atop a good foundation. This demonstrates that virtualization is not necessary for a secure base, nor sufficient to achieve highly secure systems.

Just to hammer in the point that you are heavily misinterpreting Theo's response, this is the full sentence at the start of the post that Theo was responding to:

"Virtualization seems to have a lot of security benefits. Rootkits can lie to DomU but not Dom0, and of course snapshotting, migration etc is really nice."

Wow, amazing, rootkits can never be in Dom0 because Xen has "virtualization" magic pixie dust. Theo is pointing out how this is nonsense and virtualization will only provide security if you can create implementations without glaring security holes. Furthermore, you should not just listen to the people who brought you insecure system 1 when they tell you that this time for sure they are going to give you secure system 2; maybe have just a little bit of cynicism and ask for some evidence first.

[tptacek]

You keep mentioning seL4. I'm curious what work you've done with it. (I've done a bunch of L4 work.)