Hi!

(sorry to bring up old thread).

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Intel(R) SGX is a set of CPU instructions that can be used by applications
to set aside private regions of code and data. The code outside the enclave
is disallowed to access the memory inside the enclave by the CPU access
control.  In a way you can think that SGX provides inverted sandbox. It
protects the application from a malicious host.

Do you intend to allow non-root applications to use SGX?

What are non-evil uses for SGX?

...because it is quite useful for some kinds of evil:

The default permissions for the device are 600.

Good. This does not belong to non-root.

There are entirely legitimate use cases for using this as an
unprivileged user. However, that'll be up to system and distribution
policy, which can evolve over time, and it makes sense for the *initial*
kernel permission to start out root-only and then adjust permissions via
udev.

Agreed.

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What are some non-evil uses for SGX?

Building a software certificate store. Hardening key-agent software like
ssh-agent or gpg-agent. Building a challenge-response authentication
system. Providing more assurance that your server infrastructure is
uncompromised. Offloading computation to a system without having to
fully trust that system.

I think you can do the crypto stuff... as crypto already verifies the
results. But I don't think you can do the computation offload.

As one of many possibilities, imagine a distcc that didn't have to trust
the compile nodes. The compile nodes could fail to return results at
all, but they couldn't alter the results.

distcc on untrusted nodes ... oh yes, that would be great.

Except that you can't do it, right? :-).

First, AFAICT it would be quite hard to get gcc to run under SGX. But
maybe you have spare month or three and can do it.

But ... you really can't guarantee getting right results. Evil owner
of the machine might intentionaly overheat the CPU, glitch the power,
induce single-bit errors using gamma source, ... You can't do it.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
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