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It's absolutely astounding to me that anyone could claim, with a straight face, that the PSP "enhances security". The fact that one is not even offered the opt

It's absolutely astounding to me that anyone could claim, with a straight face, that the PSP "enhances security". The fact that one is not even offered the option of disabling the PSP (or the ME for that matter) tells us everything we need to know about the true purposes of these features.

illumin8 9y ago
Isn't it somewhat like a fuse in an electric circuit? Let's say, for example, that you had perfect overvoltage protection implemented in firmware, and could disconnect the mains quickly enough to prevent damage or a fire. But, the feature is implemented in firmware, which can be modified, so a malicious individual could disable this protection and expose you to risk of damage or fire. By implementing an unmodifiable security feature (like a physical fuse), you minimize the risk of a malicious individual bypassing the protection or security control.
- takeda 9y ago
  No, it doesn't work this way. CPU has various modes that are typically switched when booting. It could allow to control it before the system boot without forgoing security. Unless... that "security" is from the users that own it.
  - illumin8 9y ago
    The security also needs to protect against an attacker that has physical access to the device. This is necessary to prevent things like extracting encryption keys.
    - takeda 9y ago
      One of things I was taught is that you can't really protect if there is a physical access. Yes, you can make it harder, but that's pretty much it. That's why anyone who is serious have multiple layers of security. Take for example Google data centers, you need access to enter the facility and access to whatever you supposed to work. There are security guards which will follow and stay with you while you are performing your work. The mechanisms in the CPUs are there to protect CPUs from their users. Let say again you are a Google and are planning to use this technology. Why would you trust a third party to decide (by signing) what can run and cannot run on the CPU. What if that 3rd party happens to be your competitor. The issue is that person/company who owns the CPU doesn't have full control over it, they can't load their own certificates and use them for signing. They need to trust 3rd party with it.
  - euyyn 9y ago
    From someone that doesn't know anything about this: Is it impossible for malware to modify that boot code?
    - bryanbuckley 9y ago
      Obviously not. Except when it can. (joke..) You can google around for secure boot, trusted boot, chain of trust, etc. Breaking secure boot is the biggest vulnerability a device can experience (e.g. Apple will pay you the most money for this type of break).
    - takeda 9y ago
      Yes, that's why things like UEFI were invented to secure the hardware. Those things are not necessarily bad, the problem is with having control over what your computer runs. It's about whether you decide that or a 3rd party that you might not necessarily trust. If things are modifiable before the machine boots, and can't be modified once system has booted, then malware should not be able to modify it.
- daxorid 9y ago
  Oh, I'm absolutely in favor of tamper-resistant hardware security modules. But I also want the freedom to turn them off. If my threat model prioritizes despotic governments with the ear of AMD/Intel/ARM Licensees over, say, phishing rings, I should have the freedom to roll the dice if I so choose. As of now, I don't have even the choice.
  - illumin8 9y ago
    Sorry, I don't understand how this prioritizes despotic governments over phishing rings. Could you please clarify that? I think the goal here is two things: 1. Allow organizations that want a trusted execution environment to refuse to boot if the OS is not signed properly, to prevent risk of unapproved software execution. 2. Prevent attackers with physical access to the device from booting an unapproved OS that might be meant to extract encryption keys, or otherwise extract or tamper with data. These are very specific attack vectors that large enterprise customers are asking for to protect their data from malicious insiders, or just anyone with physical access to the datacenter and bad intentions. That it might be used to prevent Linux from loading is simply an unintended consequence.
    - daxorid 9y ago
      I believe points 1 and 2 could be addressed by implementing a trust-on-first-use model whereby the customer can set an initial signing public key for the PSP, which is then used to sign specific boot parameters. That way, as the customer, I can tell the PSP that I'd like to either require PSP-mediated secure boot, or permit boot if the PSP is disabled. OEMs and vendors selling to enterprise customers can pre-sign it for convenience, and tinfoil hats like me can disable it. Everybody wins. But we don't even have the choice.
- Joeri 9y ago
  This is more like a fuse that can read and modify the memory of the computer it delivers power to, is accessible over the internet, and for which you cannot get the source code let alone run your own code on it.
takeda 9y ago
Because it is securing the CPU from us, users. It's sad that devices that we are losing control over devices that we are purchasing. It's not just CPUs, phones even cars :/
- astrodust 9y ago
  A lot of these CPUs are purchased not by individual consumers but by corporations. Spend ten minutes in a typical IT department and you'd want any assistance you can get in protecting the computers from users.
  - marcosdumay 9y ago
    By all means, make it an upsell. If corporations ar that interested on it (what I doubt, I've never seen the interest), it can even be an expensive upsell. But why is it shoved into everybody, and impossible to turn off?
    - astrodust 9y ago
      It's because individuals don't protest loud enough, but corporations want this. It's market pressure. Apply market pressure by raising a consumer-level fuss if you think it's important to have chips without this.
      - marcosdumay 9y ago
        Every other thing that individuals don't want badly corporations want becomes an upsell used to segment the market. But those "security" engines don't.
    - bryanbuckley 9y ago
      > But why is it shoved into everybody, and impossible to turn off? I suspect business reasons? Or lack of demand? Maybe some of the same reasons it's not open source even though there is no reason it shouldn't be? Why can't you turn this (trusted computing) stuff off on iPhones etc?
Paul-ish 9y ago
They don't want you to turn DRM off.
nhaehnle 9y ago
To be fair, the PSP is involved quite intimately in the various features for securing VMs. With the Zen processors, it should in principle be possible to send an encrypted VM to a cloud provider and be certain that this is the VM that runs, and that the cloud provider has no way of readings its RAM (thanks to RAM encryption with a PSP-generated key). External audits of those security properties are of course basically impossible, but it is true that the PSP enhances security for some use cases. AFAIK those are only data center use cases, though; ordinary users don't benefit. It's true though that while the PSP as it is today doesn't hurt users, it could be turned into an anti-user artifact in the future. That's not really in AMD's interest, though.
brudgers 9y ago
I don't disagree that these features create legitimate reasons for concern. For me, whether or not such features are attractive more or less correlates to whether or not the product is a good fit for my needs. If its not attractive, then that particular CPU SKU is not the right product and I should decide if the tradeoff of PSP for performance is worth making and if not I should choose a different product. Faced with such a decision, if I am inclined to suspect nefarious motives, I'll assume that it is just as easy to install the ARM cores or the equivalent on other chip SKU's and just not tell me via the spec sheet since I have no practical way of determining if it has been done...and hence should probably assume it has been done.

illumin8 9y ago

Isn't it somewhat like a fuse in an electric circuit? Let's say, for example, that you had perfect overvoltage protection implemented in firmware, and could disconnect the mains quickly enough to prevent damage or a fire. But, the feature is implemented in firmware, which can be modified, so a malicious individual could disable this protection and expose you to risk of damage or fire. By implementing an unmodifiable security feature (like a physical fuse), you minimize the risk of a malicious individual bypassing the protection or security control.

takeda 9y ago
No, it doesn't work this way. CPU has various modes that are typically switched when booting. It could allow to control it before the system boot without forgoing security. Unless... that "security" is from the users that own it.
- illumin8 9y ago
  The security also needs to protect against an attacker that has physical access to the device. This is necessary to prevent things like extracting encryption keys.
  - takeda 9y ago
    One of things I was taught is that you can't really protect if there is a physical access. Yes, you can make it harder, but that's pretty much it. That's why anyone who is serious have multiple layers of security. Take for example Google data centers, you need access to enter the facility and access to whatever you supposed to work. There are security guards which will follow and stay with you while you are performing your work. The mechanisms in the CPUs are there to protect CPUs from their users. Let say again you are a Google and are planning to use this technology. Why would you trust a third party to decide (by signing) what can run and cannot run on the CPU. What if that 3rd party happens to be your competitor. The issue is that person/company who owns the CPU doesn't have full control over it, they can't load their own certificates and use them for signing. They need to trust 3rd party with it.
- euyyn 9y ago
  From someone that doesn't know anything about this: Is it impossible for malware to modify that boot code?
  - bryanbuckley 9y ago
    Obviously not. Except when it can. (joke..) You can google around for secure boot, trusted boot, chain of trust, etc. Breaking secure boot is the biggest vulnerability a device can experience (e.g. Apple will pay you the most money for this type of break).
  - takeda 9y ago
    Yes, that's why things like UEFI were invented to secure the hardware. Those things are not necessarily bad, the problem is with having control over what your computer runs. It's about whether you decide that or a 3rd party that you might not necessarily trust. If things are modifiable before the machine boots, and can't be modified once system has booted, then malware should not be able to modify it.
daxorid 9y ago
Oh, I'm absolutely in favor of tamper-resistant hardware security modules. But I also want the freedom to turn them off. If my threat model prioritizes despotic governments with the ear of AMD/Intel/ARM Licensees over, say, phishing rings, I should have the freedom to roll the dice if I so choose. As of now, I don't have even the choice.
- illumin8 9y ago
  Sorry, I don't understand how this prioritizes despotic governments over phishing rings. Could you please clarify that? I think the goal here is two things: 1. Allow organizations that want a trusted execution environment to refuse to boot if the OS is not signed properly, to prevent risk of unapproved software execution. 2. Prevent attackers with physical access to the device from booting an unapproved OS that might be meant to extract encryption keys, or otherwise extract or tamper with data. These are very specific attack vectors that large enterprise customers are asking for to protect their data from malicious insiders, or just anyone with physical access to the datacenter and bad intentions. That it might be used to prevent Linux from loading is simply an unintended consequence.
  - daxorid 9y ago
    I believe points 1 and 2 could be addressed by implementing a trust-on-first-use model whereby the customer can set an initial signing public key for the PSP, which is then used to sign specific boot parameters. That way, as the customer, I can tell the PSP that I'd like to either require PSP-mediated secure boot, or permit boot if the PSP is disabled. OEMs and vendors selling to enterprise customers can pre-sign it for convenience, and tinfoil hats like me can disable it. Everybody wins. But we don't even have the choice.
Joeri 9y ago
This is more like a fuse that can read and modify the memory of the computer it delivers power to, is accessible over the internet, and for which you cannot get the source code let alone run your own code on it.

takeda 9y ago

Because it is securing the CPU from us, users. It's sad that devices that we are losing control over devices that we are purchasing. It's not just CPUs, phones even cars :/

astrodust 9y ago
A lot of these CPUs are purchased not by individual consumers but by corporations. Spend ten minutes in a typical IT department and you'd want any assistance you can get in protecting the computers from users.
- marcosdumay 9y ago
  By all means, make it an upsell. If corporations ar that interested on it (what I doubt, I've never seen the interest), it can even be an expensive upsell. But why is it shoved into everybody, and impossible to turn off?
  - astrodust 9y ago
    It's because individuals don't protest loud enough, but corporations want this. It's market pressure. Apply market pressure by raising a consumer-level fuss if you think it's important to have chips without this.
    - marcosdumay 9y ago
      Every other thing that individuals don't want badly corporations want becomes an upsell used to segment the market. But those "security" engines don't.
  - bryanbuckley 9y ago
    > But why is it shoved into everybody, and impossible to turn off? I suspect business reasons? Or lack of demand? Maybe some of the same reasons it's not open source even though there is no reason it shouldn't be? Why can't you turn this (trusted computing) stuff off on iPhones etc?

Paul-ish 9y ago

They don't want you to turn DRM off.

nhaehnle 9y ago

To be fair, the PSP is involved quite intimately in the various features for securing VMs. With the Zen processors, it should in principle be possible to send an encrypted VM to a cloud provider and be certain that this is the VM that runs, and that the cloud provider has no way of readings its RAM (thanks to RAM encryption with a PSP-generated key). External audits of those security properties are of course basically impossible, but it is true that the PSP enhances security for some use cases. AFAIK those are only data center use cases, though; ordinary users don't benefit. It's true though that while the PSP as it is today doesn't hurt users, it could be turned into an anti-user artifact in the future. That's not really in AMD's interest, though.

brudgers 9y ago

I don't disagree that these features create legitimate reasons for concern. For me, whether or not such features are attractive more or less correlates to whether or not the product is a good fit for my needs. If its not attractive, then that particular CPU SKU is not the right product and I should decide if the tradeoff of PSP for performance is worth making and if not I should choose a different product. Faced with such a decision, if I am inclined to suspect nefarious motives, I'll assume that it is just as easy to install the ARM cores or the equivalent on other chip SKU's and just not tell me via the spec sheet since I have no practical way of determining if it has been done...and hence should probably assume it has been done.