Rethinking the Linux cloud stack for confidential VMs
(lwn.net)77 points by Bogdanp 6 hours ago
77 points by Bogdanp 6 hours ago
Unfortunately, if someone really wants into modern equipment it is rather trivial. As modern clouds often just used cost-optimized consumer grade CPUs/GPUs with sometimes minor conveniences like more ECC RAM, and backplane management options.
In many ways, incident detection and automated-recovery is more important than casting your servers in concrete.
Emulated VM can create read-only signed backing images, and thus may revert/monitor states. RancherVM is actually pretty useful when you dig into the architecture.
Best policy is to waste as much time and money of the irrational, and interleave tantalizing payloads of costly project failures. Adversaries eventually realize the lame prize is just not worth the effort, or steal things that ultimately will cost them later. =3
Why do you trust your physical servers? Do you believe it is impossible for a backdoor to exist in the CPU's Management Engine? Do you inspect the contents of every single network packet entering and exiting? Do you have a way of blocking or inspecting all electromagnetic radiation?
Confidential computing is trying to solve the very problem you are worried about. It is a way of providing compute as a service without the customer having to blindly trust the compute provider. It moves the line from "the host can do anything it wants" to "we're screwed if they are collaborating with Intel to bake a custom backdoor into their CPUs".
To me that sounds like a very reasonable goal. Go much beyond that, and the only plausible attacker is going to be the kind of people who'll simply drag you to a black site and apply the big wrench until you start divulging encryption keys.
A physical server can use all the same mechanisms a VM in a cloud can use (worst case put your stuff in a single "confidential" VM), but can also rely on physical control of the machine. But there is no longer a 3rd party cloud operator in a pre-privileged position to exploit VMM or CPU vulnerabilities.
It is essentially by definition more secure than a VM anywhere.
Timely considering the current (yet another) chip act. Presumably government mandated surveillance silicon would also require confidential compute capability.
https://www.atlanticcouncil.org/blogs/geotech-cues/how-the-c...
Funny, some people never consider burning goodwill with populations directly open a competitive advantage for competitors. =3
Years ago, I saw a demo for a confidential gaming VM with the idea that games could ship with a whole VM instead of an anti cheat engine. Most of the tech was around doing it performantly. I wonder why it was never productized.
My understanding is that some modern game DRM does use an approach like that. See https://connorjaydunn.github.io/blog/posts/denuvo-analysis/
Apple has done a good job on the implementation and documentation for their confidential computing (https://security.apple.com/documentation/private-cloud-compu...) but of course it’s Apple only. There’s a few folks working on a non-Apple version of this, eg https://confident.security/ and others (disclaimer that I helped work on a very early version of this.
Read the Apple docs - they are very well written and accessible for the average HN reader.
Bit Google Cloud and AWS support confidential computing: https://cloud.google.com/security/products/confidential-comp... https://aws.amazon.com/confidential-computing/
Confidential computing is the straw for many people to overcome GDPR headaches in Europe. I know particularly medical researchers that hope that they get access to scalable infrastructure this way, because they can tick it as the only additional TOM on the processor side. As mentioned in the comments of OP though it is more a promise than a reality at the moment with very little actual benefit in term of reducing relevant attack vectors.
I find the article a difficult read for someone not versed in “confidential computing”. It felt written for insiders and/or people smarter than me.
However, I feel that “confidential computing” is some kind of story to justify something that’s not possible: keep data ‘secure’ while running code on hardware maintained by others.
Any kind of encryption means that there is a secret somewhere and if you have control over the stack below the VM (hypervisor/hardware) you’ll be able to read that secret and defeat the encryption.
Maybe I’m missing something, though I believe that if the data is critical enough, it’s required to have 100% control over the hardware.
Now go buy an Oxide rack (no I didn’t invest in them)
The unique selling point here is that you don't need to trust the hypervisor or operator, as the separation and per-VM encryption is managed by the CPU itself.
The CPU itself can attest that it is running your code and that your dedicated slice of memory is encrypted using a key inaccessible to the hypervisor. Provided you still trust AMD/Intel to not put backdoors into their hardware, this allows you to run your code while the physical machine is in possession of a less-trusted party.
It's of course still not going to be enough for the truly paranoid, but I think it provides a neat solution for companies with security needs which can't be met via regular cloud hosting.
I don't believe so? I have no doubt that there have been vulnerabilities, but the technology is quite new and barely used in practice, so I would be surprised if there have been significant exploits already - let alone ones applicable in the wild rather than a lab.
Well there were some advances in the space of homomorphic encryption, which I find pretty cool and would be an encryption which does not require a secret to work on the data. Sadly the operations which are possible are limited and quite performance intensive.
Maybe this will check a box in some OpenStack cluster but it wont work for me personally. Anything sensitive I use physical servers. Once I am on a VM of a physical server that is not mine then my data is their data. It is just turtles all the way down and there will always be a way to obtain data. Whats more this is required for lawful intercept and authorities expect providers today to be able to live copy/clone a VM. There will always be a back door and when authorities can access the back door, so can the providers and malicious actors. Even more unpopular is that to me encryption is just mathematical obfuscation a.k.a. magic math and the devil is in the implementation details remember WEP and DVD encryption? Just like cell phones there will always be some simple "debugging" toggle function that can bypass it.