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Not sure I understand your comment. Of course kernel code is executed in the guest VM…what’s the problem with that? An adversary would have to break Xen securit
by rank0 4y ago
Not sure I understand your comment. Of course kernel code is executed in the guest VM…what’s the problem with that? An adversary would have to break Xen security controls to gain access to your other domains.
- megous 4y agoVM has to have some communication bridge to the host, for all the features of the modem. That's still quite a lot of attack surface, once guest VM is compromised. It's better to not expose the needless attack surface rather than just attempting to isolate the attack into a leaky VM.
- rank0 4y agoMy understanding is that the paravirtualization provided by Xen is an effective control. The guest shouldn’t have direct access to the hardware device io right? What is the alternative? If you don’t use a VM you have to expose dom0 directly to device io. EDIT: ah I see we’re talking about a Linux phone! I agree with your point I’m not sure mobile devices have the resources to isolate every component into a VM. Overkill indeed!
- bpye 4y agoMobile devices could, if the SOC allowed every device to be isolated with an IOMMU. Apple does this, Nvidia too (though some SoCs are broken) and I think Qualcomm might as well. A lot of the other ARM SoCs seem to have just one or maybe two domains (GPU and everything else), and a non standard IOMMU for even that too. I’ve looked a few times for an ARM SBC with a nice architecture to play with this stuff, Nvidia seemed to be the only option but they are also unobtanium right now.