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Petition for AMD to open-source the PSP (backdoor) in their chips

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Re: Petition for AMD to open-source the PSP (backdoor) in their chips

#21

Post by kefka »

In all honesty, I'm waiting for a "Trusted Computing Chip" to have a key that can be set and reset.

I'd like to be able to authortatively say that a server I colo/rent is indeed mine. And given Trusted computing in a different context, I could guarantee that the machine is running my code.

And turned on to protect the file system, I could guarantee that the computer is a bastion, and that no foreign code I didn't approve is running. Then, turning on SELinux also provides another layer, where syscalls are prevented depending on RBAC level.

I could certainly see a whole lot of nice high security machines made available if AMD went the open route about this... But alas, these things usually only talk about Security from the user, to Media companies. meh, is all I can say.

Re: Petition for AMD to open-source the PSP (backdoor) in their chips

#24

Post by mrweasel »

wolfgke wrote: post #20
datatan wrote: post #17

Better option, remove the PSP. It serves no function in todays world.

> It serves no function in todays world. Wrong.

For most people it serves no function. It is kinda silly that ECC support is something you have to pay extra for, while PSP and IME is in every CPU.

Why not just leave it out and use it as an up-sell for corporate users?

Does anyone actually depend on PSP or IME for their day job? I would honestly love to hear how people use it.

Re: Petition for AMD to open-source the PSP (backdoor) in their chips

#25

Post by lallysingh »

analognoise wrote: post #18
bubblethink wrote: post #13

Earlier quoted context omitted.

>As long as there is a PSP on the system it cannot be fully controlled by the user, even if it's source code should be known. Why can't you have self-signed PSP/ME firmware ? Why is this not similar to the way android handles bootloaders ? i.e., You either have OEM's keys in the chain, or you have your own. If your employer owns the machine, they do whatever they want. If you own the machine, you do whatever you want…

It gives you the illusion of doing whatever you want, but it is still a system with complete and total access that you can't view.

How's that different from any integrated circuit?

Re: Petition for AMD to open-source the PSP (backdoor) in their chips

#26

Post by wolfgke »

mrweasel wrote: post #24
wolfgke wrote: post #20

Earlier quoted context omitted.

> It serves no function in todays world. Wrong.

For most people it serves no function. It is kinda silly that ECC support is something you have to pay extra for, while PSP and IME is in every CPU. Why not just leave it out and use it as an up-sell for corporate users? Does anyone actually depend on PSP or IME for their day job? I would honestly love to hear how people use it.

> It is kinda silly that ECC support is something you have to pay extra for,

As far as I know for Ryzen processors it is available in every processor.

> Why not just leave it out and use it as an up-sell for corporate users?

One trivial argument might be cost (indeed I consider it as plausible that it is cheaper to just produce one version of the chip).

But I also consider it as plausible that there is something deeper behind: Intel vPro (of which AMT is a part) is also used for ant theft (cf. [1]). Don't ask me about details how this is implemented - at least to my knowledge information about details are not completely trivial to find and Intel is rather secretive about anything that involves security. Now if only some Intel processors implemented Intel ME, Malory ([2]) could perhaps simply replace the processor by a one that does not implement Intel ME to circumvent the Anti Theft Technology (or at least this is something Intel fears). I consider it as rather plausible that something related to this might also be a reason why Intel does not sell processors without Intel ME (but consider this paragraph as speculative).

[1] https://en.wikipedia.org/w/index.php?title=Intel_vPro&oldid=...

[2] https://en.wikipedia.org/w/index.php?title=Alice_and_Bob&act...

Re: Petition for AMD to open-source the PSP (backdoor) in their chips

#27

Post by wolfgke »

kefka wrote: post #21

In all honesty, I'm waiting for a "Trusted Computing Chip" to have a key that can be set and reset. I'd like to be able to authortatively say that a server I colo/rent is indeed mine. And given Trusted computing in a different context, I could guarantee that the machine is running my code. And turned on to protect the file system, I could guarantee that the computer is a bastion, and that no foreign code I didn't app…

> In all honesty, I'm waiting for a "Trusted Computing Chip" to have a key that can be set and reset.

The "trusted" in "trusted computing" is used as it is defined in IT security (but not in the sense how an "ordinary user" understands it).

In this case "trusted" means that one can trust the computation since the user has no option to change it/have control over it. Because if they had, we could not trust the result of the computation since the user might have modified something etc.

In other words: If the user has such a freedom, we cannot trust the computation, but we have to trust the user.

Thus "trusted computing" that gives freedom to the machine owner is impossible.

If you buy a PC or laptop this is often not what you want (at least for the HN audience). IOW: Here in most cases you don't want trusted computing.

On the other hand, if you rent a server, you would love to have the trust that the data center provider cannot intercept/modify etc. what you do on the server. For this situation you consider the machine owner (datacenter operator) as potentially malicious and want technology where you can trust the computation.

Re: Petition for AMD to open-source the PSP (backdoor) in their chips

#28

Post by analognoise »

bubblethink wrote: post #19
analognoise wrote: post #18

Earlier quoted context omitted.

It gives you the illusion of doing whatever you want, but it is still a system with complete and total access that you can't view.

Why is it an illusion if you have the source ? You get the source, build it, sign it, and flash it. You can't verify that CPU will only accept your signed firmware and not something else under special circumstances, but you can't verify those sort of cases in hardware anyway. The CPU is a black box at the end of the day. Edit: Disabling becomes a special case of flashing in this case. Actual hardware disabling will l…

Exactly right; the CPU is a black box.

There's nothing stopping a PSP/IME from waking up on a magic packet, executing code that doesn't exists in flash (say, it is cleverly crafted into what looks like dummy transistors used to ensure an equal metallization layer), downloading new firmware from a C&C server, and re-flashing itself.

If you want to actually own the hardware, you'd probably need a custom chip layout all done by hand on a planar node so it was easily verifiable by a third party with relatively inexpensive tools; things like dopant-level attacks assume access to the machine physically as far as I know.

If you assume that a fab could be hostile, you'd have to zero the foundry attack surface.

This hypothetical chip would be dog slow and uncompetitive, but by god, it'd be yours.

Re: Petition for AMD to open-source the PSP (backdoor) in their chips

#29

Post by kefka »

wolfgke wrote: post #27
kefka wrote: post #21

In all honesty, I'm waiting for a "Trusted Computing Chip" to have a key that can be set and reset. I'd like to be able to authortatively say that a server I colo/rent is indeed mine. And given Trusted computing in a different context, I could guarantee that the machine is running my code. And turned on to protect the file system, I could guarantee that the computer is a bastion, and that no foreign code I didn't app…

> In all honesty, I'm waiting for a "Trusted Computing Chip" to have a key that can be set and reset. The "trusted" in "trusted computing" is used as it is defined in IT security (but not in the sense how an "ordinary user" understands it). In this case "trusted" means that one can trust the computation since the user has no option to change it/have control over it. Because if they had, we could not trust the result…

And I would accuse you of thinking in the narrow line of "TPM for media companies to control your hardware". There are other ways to go about this..

Think of the ORWL. It's a heavy crypto system that will delete its keys if it's tampered with (heat, cold, shock, pressure, penetration). If I hand these keys to someone else, they have control over the software installed. If they lose the keys, they're out of luck. If the device thinks there's a tampering, they're out of luck.

Now, this may be installed in my datacenter. Awesome. If I mess with it, it's easy to detect. Because everything auto-deletes on tamper. So it is my device by possession, but someone else controls it as I choose for the duration they have the keys.

This would be a great way to run secure systems, as I mentioned further up. Yes, I can run it in a datacenter, but I don't have to trust the datacenter. It's not impenetrable, but it's a heck of a lot better than other solutions.

(Yes, I'm still waiting for reasonably fast homomorphic encryption and processing. But I know that'll be a long time away. Even if Signal is doing some work on that area, the processing side is still about 7000x too slow.)

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