8 ms·

Secure Boot in the Era of the T2

106 points by archvile 8y ago

sudo-i 8y ago
Does this have any bearing on running linux on macbooks?
- monocasa 8y ago
  AFAIK, there's no way to inject new keys, so you have a exclusive choice between running Linux and having secure boot enabled. So it doesn't stop you in a way a game console might, but you lose some features of the hardware by doing so.
  - MrBingley 8y ago
    Even with secure boot disabled you can't install Linux on the internal SSD. Installing Linux on a Mac has already been very flaky for the last few years, but now is impossible. https://unix.stackexchange.com/questions/463422/how-can-you-get-any-version-of-linux-to-see-the-2018-macbook-pro-ssd https://unix.stackexchange.com/questions/463422/how-can-you-...
    - nneonneo 8y ago
      The likely problem is a lack of driver support for using the T2 as an SSD controller. I don’t think, based on Apple’s white paper, that they did anything to explicitly block Linux from accessing the internal SSD - it just needs to go through the T2 for that. Hopefully someone is working on the necessary driver support - these laptops are still very new so maybe nobody has gotten around to it yet.
      - saagarjha 8y ago
        Yes, the issue is that Linux doesn’t know how to talk to the SSD, not Apple stopping Linux from accessing the SSD.
      - michaelmrose 8y ago
        Apple is actively blocking unsigned software from accessing the internal storage as a security measure and providing no means to add allowed keys. Its possible there is a defect in this security that could be exploited but it would be explicitly a bug and would be liable to be patched in the next version of the software. You have completely misread the situation. This is apple taking over your machine while still expecting you to pay for it.
        yeloboy 8y ago
        Not if you disable secure boot. Imo they're probably right about Linux not being able to talk to T2. We'll see about that, I guess.
    - grecy 8y ago
      Interesting that Windows 10 installed via Boot Camp is an allowable exception, but Linux is not. I wonder if Apple have an official stance on that.. i.e. "we're working on it", or "never".
      - saagarjha 8y ago
        This is because Apple has included the keys for Windows, but has not added the Microsoft UEFI key for Linux.
- josteink 8y ago
  > Does this have any bearing on running linux on macbooks Unlike on PCs, on T2 Macs Linux will only be bootable with Secure boot disabled making the system much less secure. To make matters worse, the T2 chip administers access to the built in SSD, so it will be completely inaccessible for Linux to use for anything. When Apple stops supporting this machine, you won’t be able to keep it chugging by loading another OS. I could say Apple is trying to terminate the only remaining computing platform which respects end-user freedom and ownership, but I’m not sure if it would be a joke or not...
  - saagarjha 8y ago
    > the T2 chip administers access to the built in SSD, so it will be completely inaccessible for Linux to use for anything. This isn’t true. You can install Linux on this, providing you disable Secure Boot. You can’t currently access the SSD, but that’s more the result of a driver not existing than it being inherently disallowed.
    - Dunedan 8y ago
      > You can’t currently access the SSD, but that’s more the result of a driver not existing than it being inherently disallowed. That's not clear yet. There is a NVMe driver available in Linux which works fine with pre-T2 Macs. On T2 Macs however the whole platform resets a few seconds after initializing the NVMe controller. The question is: Is that a bug in the driver or NVMe implementation of the T2 chip or something Apple does intentionally?
      - X-Istence 8y ago
        Let's not attribute to malice what can easily be attributed to incompetence.
        floatboth 8y ago
        In a chip that has "secure" in its name, it's quite likely that a sudden system shutdown is intentional..
Shank 8y ago
> Apple should be lauded for trying to bring their laptop and desktop lines into the same defensive posture as their mobile offerings. I think this can't be stated enough. The fact of the matter is that pre T2, evil maid attacks were ridiculously easy. Now they're at least as secure as iOS -- which also means that shared vulnerabilities can be patched and detected. By no means is it perfect security, but it's a heck of a lot better than "stick boot disk in and gain keys to the kingdom." For so long we've gone by the mantra that physical access means you have root. Now we're a step ahead of that -- which is great for data privacy.
- userbinator 8y ago
  which is great for data privacy. ...and absolutely horrible for freedom. It used to be the case, and still widely accepted for a lot of other products, that physical ownership actually meant something beyond just being a consumer. Now companies are turning the security against users, lest they also be attackers. From the point of view of the DRM-advocating media corporations, the user is an attacker. Locking down the platform to allow only "trusted" (not by you, but by them!) code only benefits when their goals align with yours; you may agree with them on not wanting things like ransomware, but not on things like them not allowing you to share a file between two apps or even run code you wrote yourself. It's scarier than any security attack to see what used to be an open and free platform turned into a walled garden of corporate control and obedience. (Insert famous Benjamin Franklin quote.)
  - scarface74 8y ago
    Tell that to the million of Windows users that have 10 toolbars on their browser, ransomware, etc....
    - LeoNatan25 8y ago
      2001 called, it wants its outdated Windows memes back.
      - 8y ago
akvadrako 8y ago
The T2 does so much, essentially running an OS comparable to iOS. The author even suggests it might allow apps. It doesn't seem like it's a gain in security. Instead of attacking the "main system", you can just attack the T2; it's similar in complexity, meaning it will have similar vulnerabilities.
- IMcD23 8y ago
  Try pulling data off my iPhone with physical access. Now, try pulling data off a pre-T2 Mac. The T2 brings many security improvements to the Mac.
  - akvadrako 8y ago
    It's not because of the T2 though - it's because of the Secure Enclave holding the keys for disk encryption and firmware/kernel signatures. They might have bundled them together, but the layer around the secure part is just another system - it doesn't make anything more secure. All it's functions could have been taken up by the main system. The only possible security win is by making BridgeOS simpler and less likely to have vulnerabilities.
    - lloeki 8y ago
      I'd still say it's a net gain overall†, although the Great Bundling is questionable and definitely concerning in terms of attack surface, yet the synergies when finding and fixing vulnerabilities should not be taken lightly. † It's overall a good thing evil maid/law enforcement/whatever doesn't get to have trivial access to the user's device anymore.
cmurf 8y ago
The article reinforces my disappointment in Apple. First they use an Apple variant of Intel EFI 1.10 forever, even well passed the time UEFI incorporated Secure Boot. Instead of writing up a critique and proposal to fix any problems/limitations with UEFI Secure Boot, Apple has to go do a damned proprietary thing. Again. Also, the latest Macs do not contain the Microsoft UEFI signing key, only the Microsoft Windows and Applel signing keys. So the only way to boot Linux is to disable Secure Boot, leaving people less secure.
josteink 8y ago
> We believe the T2 platform is a leap forward in platform security in the Apple ecosystem, and it begins to bring exciting security properties like Secure Boot capabilities to the mass market. So the vast PC-market with UEFI secure boot which predates this by 6 year was somehow not the “mass market”, but the relatively tiny MacBook market is? With factual errors like this present already in the introduction, it’s hard to take anything which follows it seriously. This just comes off like fanboy-fluff.
- nneonneo 8y ago
  Serious question - how well does UEFI secure boot protect against an attacker with a high degree of physical access to the machine? Online docs focus mostly on the software/firmware security but less on the hardware side. Is hardware security specified, or left up to individual vendors?
  - josteink 8y ago
    > how well does UEFI secure boot protect against an attacker with a high degree of physical access to the machine? Everything is relative. When enabled, what Secure Boot ensures is that only boot media signed by a trusted a key (which unless user-replaced, typically are the vendor-provided key which trusts MS Windows and common Linux-distros) can be booted. This guarantees that the base OS and kernel booted by the machine can be trusted to not be tampered with by untrusted parties. That is, the most important part of the OS is protected against malicious modifications and attacks by the firmware. However if this is the only security-measure you have, there is nothing preventing a physical attacker from extracting the drive into another machine, and on this machine modify non-boot related OS-files to introduce a backdoor or trojan, and then put the drive back into the original machine. You will then boot a trusted kernel, which later on may load malicious code. Secure boot alone does not protect against a scenario like this. But if you use Secure Boot together with and BitLocker, LUKS or other full-disk encryption solutions, you should be reasonably secure, even against physical attackers. Basically Secure Boot is not a full security solution, but it is the base which you need for a fully trusted, tamper-proof computing environment. Without it, you wouldn't know if someone is logging your password or not when unlocking the encrypted drives.

106 points by archvile 8y ago

sudo-i 8y ago

Does this have any bearing on running linux on macbooks?

monocasa 8y ago
AFAIK, there's no way to inject new keys, so you have a exclusive choice between running Linux and having secure boot enabled. So it doesn't stop you in a way a game console might, but you lose some features of the hardware by doing so.
- MrBingley 8y ago
  Even with secure boot disabled you can't install Linux on the internal SSD. Installing Linux on a Mac has already been very flaky for the last few years, but now is impossible. https://unix.stackexchange.com/questions/463422/how-can-you-get-any-version-of-linux-to-see-the-2018-macbook-pro-ssd https://unix.stackexchange.com/questions/463422/how-can-you-...
  - nneonneo 8y ago
    The likely problem is a lack of driver support for using the T2 as an SSD controller. I don’t think, based on Apple’s white paper, that they did anything to explicitly block Linux from accessing the internal SSD - it just needs to go through the T2 for that. Hopefully someone is working on the necessary driver support - these laptops are still very new so maybe nobody has gotten around to it yet.
    - saagarjha 8y ago
      Yes, the issue is that Linux doesn’t know how to talk to the SSD, not Apple stopping Linux from accessing the SSD.
    - michaelmrose 8y ago
      Apple is actively blocking unsigned software from accessing the internal storage as a security measure and providing no means to add allowed keys. Its possible there is a defect in this security that could be exploited but it would be explicitly a bug and would be liable to be patched in the next version of the software. You have completely misread the situation. This is apple taking over your machine while still expecting you to pay for it.
      - yeloboy 8y ago
        Not if you disable secure boot. Imo they're probably right about Linux not being able to talk to T2. We'll see about that, I guess.
  - grecy 8y ago
    Interesting that Windows 10 installed via Boot Camp is an allowable exception, but Linux is not. I wonder if Apple have an official stance on that.. i.e. "we're working on it", or "never".
    - saagarjha 8y ago
      This is because Apple has included the keys for Windows, but has not added the Microsoft UEFI key for Linux.
josteink 8y ago
> Does this have any bearing on running linux on macbooks Unlike on PCs, on T2 Macs Linux will only be bootable with Secure boot disabled making the system much less secure. To make matters worse, the T2 chip administers access to the built in SSD, so it will be completely inaccessible for Linux to use for anything. When Apple stops supporting this machine, you won’t be able to keep it chugging by loading another OS. I could say Apple is trying to terminate the only remaining computing platform which respects end-user freedom and ownership, but I’m not sure if it would be a joke or not...
- saagarjha 8y ago
  > the T2 chip administers access to the built in SSD, so it will be completely inaccessible for Linux to use for anything. This isn’t true. You can install Linux on this, providing you disable Secure Boot. You can’t currently access the SSD, but that’s more the result of a driver not existing than it being inherently disallowed.
  - Dunedan 8y ago
    > You can’t currently access the SSD, but that’s more the result of a driver not existing than it being inherently disallowed. That's not clear yet. There is a NVMe driver available in Linux which works fine with pre-T2 Macs. On T2 Macs however the whole platform resets a few seconds after initializing the NVMe controller. The question is: Is that a bug in the driver or NVMe implementation of the T2 chip or something Apple does intentionally?
    - X-Istence 8y ago
      Let's not attribute to malice what can easily be attributed to incompetence.
      - floatboth 8y ago
        In a chip that has "secure" in its name, it's quite likely that a sudden system shutdown is intentional..

Shank 8y ago

> Apple should be lauded for trying to bring their laptop and desktop lines into the same defensive posture as their mobile offerings. I think this can't be stated enough. The fact of the matter is that pre T2, evil maid attacks were ridiculously easy. Now they're at least as secure as iOS -- which also means that shared vulnerabilities can be patched and detected. By no means is it perfect security, but it's a heck of a lot better than "stick boot disk in and gain keys to the kingdom." For so long we've gone by the mantra that physical access means you have root. Now we're a step ahead of that -- which is great for data privacy.

userbinator 8y ago
which is great for data privacy. ...and absolutely horrible for freedom. It used to be the case, and still widely accepted for a lot of other products, that physical ownership actually meant something beyond just being a consumer. Now companies are turning the security against users, lest they also be attackers. From the point of view of the DRM-advocating media corporations, the user is an attacker. Locking down the platform to allow only "trusted" (not by you, but by them!) code only benefits when their goals align with yours; you may agree with them on not wanting things like ransomware, but not on things like them not allowing you to share a file between two apps or even run code you wrote yourself. It's scarier than any security attack to see what used to be an open and free platform turned into a walled garden of corporate control and obedience. (Insert famous Benjamin Franklin quote.)
- scarface74 8y ago
  Tell that to the million of Windows users that have 10 toolbars on their browser, ransomware, etc....
  - LeoNatan25 8y ago
    2001 called, it wants its outdated Windows memes back.
    - 8y ago

akvadrako 8y ago

The T2 does so much, essentially running an OS comparable to iOS. The author even suggests it might allow apps. It doesn't seem like it's a gain in security. Instead of attacking the "main system", you can just attack the T2; it's similar in complexity, meaning it will have similar vulnerabilities.

IMcD23 8y ago
Try pulling data off my iPhone with physical access. Now, try pulling data off a pre-T2 Mac. The T2 brings many security improvements to the Mac.
- akvadrako 8y ago
  It's not because of the T2 though - it's because of the Secure Enclave holding the keys for disk encryption and firmware/kernel signatures. They might have bundled them together, but the layer around the secure part is just another system - it doesn't make anything more secure. All it's functions could have been taken up by the main system. The only possible security win is by making BridgeOS simpler and less likely to have vulnerabilities.
  - lloeki 8y ago
    I'd still say it's a net gain overall†, although the Great Bundling is questionable and definitely concerning in terms of attack surface, yet the synergies when finding and fixing vulnerabilities should not be taken lightly. † It's overall a good thing evil maid/law enforcement/whatever doesn't get to have trivial access to the user's device anymore.

cmurf 8y ago

The article reinforces my disappointment in Apple. First they use an Apple variant of Intel EFI 1.10 forever, even well passed the time UEFI incorporated Secure Boot. Instead of writing up a critique and proposal to fix any problems/limitations with UEFI Secure Boot, Apple has to go do a damned proprietary thing. Again. Also, the latest Macs do not contain the Microsoft UEFI signing key, only the Microsoft Windows and Applel signing keys. So the only way to boot Linux is to disable Secure Boot, leaving people less secure.

josteink 8y ago

> We believe the T2 platform is a leap forward in platform security in the Apple ecosystem, and it begins to bring exciting security properties like Secure Boot capabilities to the mass market. So the vast PC-market with UEFI secure boot which predates this by 6 year was somehow not the “mass market”, but the relatively tiny MacBook market is? With factual errors like this present already in the introduction, it’s hard to take anything which follows it seriously. This just comes off like fanboy-fluff.

nneonneo 8y ago
Serious question - how well does UEFI secure boot protect against an attacker with a high degree of physical access to the machine? Online docs focus mostly on the software/firmware security but less on the hardware side. Is hardware security specified, or left up to individual vendors?
- josteink 8y ago
  > how well does UEFI secure boot protect against an attacker with a high degree of physical access to the machine? Everything is relative. When enabled, what Secure Boot ensures is that only boot media signed by a trusted a key (which unless user-replaced, typically are the vendor-provided key which trusts MS Windows and common Linux-distros) can be booted. This guarantees that the base OS and kernel booted by the machine can be trusted to not be tampered with by untrusted parties. That is, the most important part of the OS is protected against malicious modifications and attacks by the firmware. However if this is the only security-measure you have, there is nothing preventing a physical attacker from extracting the drive into another machine, and on this machine modify non-boot related OS-files to introduce a backdoor or trojan, and then put the drive back into the original machine. You will then boot a trusted kernel, which later on may load malicious code. Secure boot alone does not protect against a scenario like this. But if you use Secure Boot together with and BitLocker, LUKS or other full-disk encryption solutions, you should be reasonably secure, even against physical attackers. Basically Secure Boot is not a full security solution, but it is the base which you need for a fully trusted, tamper-proof computing environment. Without it, you wouldn't know if someone is logging your password or not when unlocking the encrypted drives.