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To study how chips work, MIT researchers built their own operating system

news.mit.edu

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Re: To study how chips work, MIT researchers built their own operating system

#31

Post by saagarjha »

JdeBP wrote: post #13
saagarjha wrote: post #12

Earlier quoted context omitted.

I assume the idea is that finding tools and assembling other projects together into a build environment is comparatively easy but papering over entire components being missing is much harder

No. As I said, that's really a secondary niggle with the paper itself misrepresenting its reference, which as you can see already provides patches to paper over such stuff, as through the problem with XNU were redaction, which it isn't per that reference. The primary reason not to use XNU is what the paper goes into in detail; which is the architecture of XNU simply getting in the way, just as the architecture of Net…

Just because someone did it doesn't make it easy? I found the reference to support the claim fairly well

Re: To study how chips work, MIT researchers built their own operating system

#32

Post by exe34 »

asdewqqwer wrote: post #27
ReptileMan wrote: post #26

Earlier quoted context omitted.

Feel free to suggest a more suitable word. Research is usually defined against the the body of knowledge of the entity performing it and not all of humanity that ever lived.

Yet a published peer-reviewed research should be against humanity. I am also curious whether such research can bring knowledge that apple don't know, otherwise even it is impressive, there is a level of sadness in it from my view.

No it's against what's published by all of humanity. So if somebody knows something and hasn't published it, someone else can still scoop them.

Re: To study how chips work, MIT researchers built their own operating system

#33

Post by kwk1 »

j16sdiz wrote: post #21

I am very confused by calling this kind of work "researches". They are not pushing the boundary of human knowledge - they are playing game (reverse engineering) with other human.. maybe that is me having a very narrow definition of "research"

What you are talking about is sometimes called "basic research":

https://en.wikipedia.org/wiki/Basic_research

Re: To study how chips work, MIT researchers built their own operating system

#34

Post by voodooEntity »

jprx wrote: post #17

Hi everyone, Joseph (paper author) here. You can find Fractal on Github: https://github.com/jprx/fractal The full paper, slides from my S&P talk, and all our experiment data can be found at the Fractal project website here: https://fractal-os.com We've been building Fractal internally for a very long time (first commit was almost exactly 2 years ago), so it's exciting to finally share it with the world. Let me know w…

chapeau for this project - and thanks for sharing it with the world!

Re: To study how chips work, MIT researchers built their own operating system

#35

Post by costco »

landr0id wrote: post #14

Not to take away from the authors' work, but this was actually the approach taken by some engineers while Spectre / Meltdown were still under embargo. Not sure if they ever mentioned their work publicly so I will avoid naming them, but some talented folks from Microsoft who basically came to the same conclusion that a specialized environment free of noise was necessary both to test mitigations and find variants.

Related (2019):

https://gamozolabs.github.io/metrology/2019/08/19/sushi_roll...

https://gamozolabs.github.io/metrology/2019/12/30/load-port-...

Re: To study how chips work, MIT researchers built their own operating system

#36

Post by acka »

jprx wrote: post #19
hamburgererror wrote: post #18

Earlier quoted context omitted.

Can it run Doom?

Haven't gotten around to it yet haha

Studying how a processor running an operating system actually behaves by peeking right through the privilege barrier is the ultimate wall hack. Who needs noclip when we have Fractal?

Re: To study how chips work, MIT researchers built their own operating system

#37

Post by nippoo »

dataflow wrote: post #22
jprx wrote: post #17

Hi everyone, Joseph (paper author) here. You can find Fractal on Github: https://github.com/jprx/fractal The full paper, slides from my S&P talk, and all our experiment data can be found at the Fractal project website here: https://fractal-os.com We've been building Fractal internally for a very long time (first commit was almost exactly 2 years ago), so it's exciting to finally share it with the world. Let me know w…

At the risk of sounding extremely dumb, I have a question for you: if the hardware is susceptible to something that you can't actually reproduce with the software everyone runs on it, who should care, and why? Is it even really fair to call it a vulnerability at that point? Is the idea that this is supposed to help identify a different mechanism of exploiting the vulnerabilities with the shipped OS too? To give an an…

Great analogy. Li-ion batteries have several layers of defense against exploding, one of which are vents that, if all else fails, let the hydrogen gas safely escape rather than building up. It's perfectly fair for independent testers to say "we haven't found any flaws in the protection circuitry yet, but we should bypass it to see if the vents work as designed".

Re: To study how chips work, MIT researchers built their own operating system

#38

Post by pfannl »

dataflow wrote: post #22
jprx wrote: post #17

Hi everyone, Joseph (paper author) here. You can find Fractal on Github: https://github.com/jprx/fractal The full paper, slides from my S&P talk, and all our experiment data can be found at the Fractal project website here: https://fractal-os.com We've been building Fractal internally for a very long time (first commit was almost exactly 2 years ago), so it's exciting to finally share it with the world. Let me know w…

At the risk of sounding extremely dumb, I have a question for you: if the hardware is susceptible to something that you can't actually reproduce with the software everyone runs on it, who should care, and why? Is it even really fair to call it a vulnerability at that point? Is the idea that this is supposed to help identify a different mechanism of exploiting the vulnerabilities with the shipped OS too? To give an an…

The real benchmark is whether it can run Doom while measuring why Doom runs.

Re: To study how chips work, MIT researchers built their own operating system

#39

Post by vlovich123 »

jprx wrote: post #17

Hi everyone, Joseph (paper author) here. You can find Fractal on Github: https://github.com/jprx/fractal The full paper, slides from my S&P talk, and all our experiment data can be found at the Fractal project website here: https://fractal-os.com We've been building Fractal internally for a very long time (first commit was almost exactly 2 years ago), so it's exciting to finally share it with the world. Let me know w…

I didn’t quite understand the scope of impact of the issues highlighted in the article.

> The CPU still fetches the target into the instruction cache before the protection kicks in.

> In Phantom, ordinary instructions, including a no-op, can be misinterpreted by the CPU as branches, triggering speculative behavior the program never asked for.

Is the idea you combine these two to execute a BTB style attack? Is there a world in which speculative cache fetching is still fine if it’s non exploitable or is it always a risk and the performance cost of fixing the hardware negligible?

> The Fractal team showed that the conditional branch predictor has no privilege isolation at all

This one seems more serious. Now that it’s confirmed, does it provide a map for how to exploit it in a real system or is this non-exploitable in practice because of OS design choices around migration?

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