Re: [PATCH v1 00/15] Add support for Nitro Enclaves

Paolo Bonzini
2020-04-30T11:58:24Z

On 30/04/20 13:47, Alexander Graf wrote:
>>
>> So the issue would be that a firmware image provided by the parent could
>> be tampered with by something malicious running in the parent enclave?
>
> You have to have a root of trust somewhere. That root then checks and
> attests everything it runs. What exactly would you attest for with a
> flat address space model?
>
> So the issue is that the enclave code can not trust its own integrity if
> it doesn't have anything at a higher level attesting it. The way this is
> usually solved on bare metal systems is that you trust your CPU which
> then checks the firmware integrity (Boot Guard). Where would you put
> that check in a VM model?

In the enclave device driver, I would just limit the attestation to the
firmware image

So yeah it wouldn't be a mode where ne_load_image is not invoked and
the enclave starts in real mode at 0xffffff0. You would still need
"load image" functionality.

> How close would it be to a normal VM then? And
> if it's not, what's the point of sticking to such terrible legacy boot
> paths?

The point is that there's already two plausible loaders for the kernel
(bzImage and ELF), so I'd like to decouple the loader and the image.

Paolo