7 ms·

Implementing UEFI Secure Boot in Fedora

79 points by Garbage 14y ago

zurn 14y ago
Anyone know what kind of key revocation mechanisms Microsoft have in place?
- yungchin 14y ago
  See http://ozlabs.org/docs/uefi-secure-boot-impact-on-linux.pdf http://ozlabs.org/docs/uefi-secure-boot-impact-on-linux.pdf section 2.3: "This is known in the UEFI specification as the “forbidden signatures database”, and is modifiable during execution by authenticated software."
sounds 14y ago
I've never thought UEFI Secure Boot was a great idea, but Fedora paying Microsoft to get a signed boot loader feels, errrm, creepy to me. On the bright side however, Fedora's boot loader is just a signature verifying loader to boot grub2 - using _Fedora's_ PKI. That's encouraging because at an ideological level it's exploiting Microsoft's process to give Fedora control over everything downstream from their loader. The name even implies that it's a kind of workaround: "shim loader." (Shim is defined in some circles as a compatibility workaround.) I guess Fedora doesn't plan on becoming a signing authority for custom kernels, but in a pinch it could work. Please, everyone start contributing to http://coreboot.org http://coreboot.org ! [Edited for clarity.]
- av500 14y ago
  it does not give Fedora "control over the whole process". It's not only the bootloader that is signed, it's also kernel and modules. And if any of these is compromised, M$ can see that as a threat to a Windows installation on the same PC and revoke the "Fedora" keys. Not that M$ would have any incentive to do such a thing ever....
- lucian1900 14y ago
  As long as OEMs only listen to MS, coreboot will never happen. Even with UEFI, this doesn't have to be a problem.
  - sounds 14y ago
    Unless I misunderstand what you mean by "will never happen," I think you should take a second look at coreboot. It's happening. It's just not on _your_ laptop, but it could be. Try it out.
saulrh 14y ago
Microsoft will be offering signing services through their sysdev portal. It's not entirely free (there's a one-off $99 fee to gain access) In other words, Microsoft won. Not only have they made Linux significantly more difficult to develop and use, they have managed to actually extract money from open-source developers. This is why MS has such a bad reputation.
- InclinedPlane 14y ago
  I don't get it. My reading is that MS will sign Linux distros for a lifetime fee of $100 per vendor. That doesn't sound like MS is going to be living high off the hog from those proceeds, it sounds like a reasonable fee to prevent abuse of the system. Also, as far as I can tell a user (or an OEM) can just go into their UEFI settings and turn off secure boot, then install and boot completely unsigned anything. This doesn't seem like the end of the world to me.
  - slowpoke 14y ago
    >I don't get it. My reading is that MS will sign Linux distros for a lifetime fee of $100 per vendor. That's besides the point. It's that Microsoft - a software vendor - is suddenly the authority over distributing and signing keys for what amounts to a hardware lock mechanism that prevents you from doing whatever the fuck you want with your computer, all in the name of a false pretext of security. This is insanity. >Also, as far as I can tell a user (or an OEM) can just go into their UEFI settings and turn off secure boot, then install and boot completely unsigned anything. The problem is with what you've conveniently placed into parentheses - if the OEM decides to not give you the ability to turn it off, you're fucked. A hardware vendor should not have the ability to tell me what the fuck I can run off it. I'll admit that this is getting into slippery slope territory, but I can see a lot of OEMs using this "feature" because, hey, it worked for Apple - it can't be that bad⸮
    - cooldeal 14y ago
      >all in the name of a false pretext of security How is it false? Rootkits are a real danger, because they can be undetectable by any antivirus you can run. It's funny because many of same people attacking Microsoft here turn around and claim that Microsoft software is insecure and recommend you switch to OS X/Linux! >if the OEM decides to not give you the ability to turn it off, you're fucked In order to qualify for the Windows Logo, OEMs are REQUIRED by Microsoft to give the user the ability to turn it off or add their own keys. As such, UEFI software will have this feature anyway, so I seriously doubt any OEM would not do that, since they aren't saving anything and only the tech savvy will mess with the settings anyway.
gioele 14y ago
> Our first stage bootloader will be signed with a Microsoft key. It is a sad sad day.
rwmj 14y ago
So Microsoft will sign just about any bootloader for a one-off fee of $99? What's to stop me setting up a legit-looking company, writing a fake bootloader, getting it signed, then adding malware to Windows? If the key is blacklisted, I'll just sign up for another one. The whole idea of secure booting on hardware that you don't physically control is ridiculous anyway. You're trusting everything in that chain of software, from the bootloader, through the OS, through to every ring 0 driver, to not contain any exploitable bug. We know how well that worked out, just look at consoles & Android. Microsoft aren't stupid. They know this isn't going to provide real security. I think the intention is (a) prevent people easily repurposing machines to run Linux, (b) provide a sop to Big Content, (c) set expectations that you don't own the hardware you bought.
- deleted 14y ago
  [deleted]
- tzs 14y ago
  > I think the intention is (a) prevent people easily repurposing machines to run Linux Serious question: are there really many people who • know enough to take a Windows machine, obtain a Linux boot CD or boot USB drive, do whatever voodoo is required to make the computer boot from that instead of from the hard disk, and then go through the Linux install, but who cannot easily • figure out how to invoke the BIOS settings menu and change the secure boot option from "enabled" to "disabled" ? I understand that Linux is getting friendlier to non-techies, and many people report success in getting Grandma using Linux, but in almost all of these stories they installed Linux for Grandma. They did not just toss her a CD and say "try this!".
  - rwmj 14y ago
    It's an extra step in the process. Plus if you're dual booting, you have to switch the BIOS back and forth every time you switch between "secure" Windows 8 and Linux.
dhx 14y ago
Matthew’s earlier article “Why UEFI secure boot is difficult for Linux” is worth reading: http://mjg59.dreamwidth.org/9844.html http://mjg59.dreamwidth.org/9844.html
josteink 14y ago
Why does a computer (a physical general computation device) need, require or trust keys from Microsoft (one singular software vendor) in the first place? If this isn't defined as monopoly-abuse, I don't know what is.
- apetrovic 14y ago
  Just build a computer, a physical general computation device, with a motherboard that doesn't have Windows sticker on the box (the shiny thing issued by Microsoft) and you should be fine.
  - josteink 14y ago
    While that is a valid solution to the problem, it is also tippy-toing around why the problem is there in the first place. And that is what I was curious about.
- zokier 14y ago
  Computer doesn't require them. But your OEM has Micrsoft keys preinstalled to run the preinstalled Windows. Note this part: >While Microsoft have modified their original position and all x86 Windows machines will be required to have a firmware option to disable this or to permit users to enrol their own keys, it's not really an option to force all our users to play with hard to find firmware settings before they can run Fedora Two things can be picked from that quote: 1) If you don't want to trust MS, then put in your own keys. 2) Fedora got their bootloader signed for convenience, not because it would be required.
  - krakensden 14y ago
    It's not required now, but it will be to get a Windows 8 Certified logo. Which means basically everything will have it when Windows 8 comes out.
    - tzs 14y ago
      No. The original Windows 8 logo requirements were that secure boot be enabled by default, and were silent on whether or not the OEM could provide an option to disable it. Microsoft updated the requirements to say that OEMs must provide, on x86, a way to disable it or allow users to install their own keys.
conductor 14y ago
I wonder, once every piece of motherboards are shipped with MS key, how much CPU time would be needed to factor the private key and sign anything? Some distributed piece of software running on thousands of anonymous machines should solve the problem in weeks I think, or not?
- zurn 14y ago
  A SSL cert vendor has a popularized writeup for 2048-bit RSA (which UEFI uses according to http://www.uefi.org/learning_center/UEFI_Plugfest_2012Q1_v3_AMI.pdf http://www.uefi.org/learning_center/UEFI_Plugfest_2012Q1_v3_...) at http://www.digicert.com/TimeTravel/math.htm http://www.digicert.com/TimeTravel/math.htm: "[...] It is therefore estimated, that standard desktop computing power would take 4,294,967,296 x 1.5 million years to break a DigiCert 2048-bit SSL certificate. Or, in other words, a little over 6.4 quadrillion years."
rcthompson 14y ago
What if you bought a new house and the bank you bought it from told you that they would be keeping your house keys and not giving you a copy? It's not the most accurate analogy, but the point is that UEFI puts a lock on the boot process, which is itself arguably a good thing, but then Microsoft and others are trying to control the keys that rightfully belong to the owner of the hardware. Or more simply, locks are not bad per se, but if you aren't allowed to have the key to a lock that you supposedly own, then that's bad.

79 points by Garbage 14y ago

zurn 14y ago

Anyone know what kind of key revocation mechanisms Microsoft have in place?

yungchin 14y ago
See http://ozlabs.org/docs/uefi-secure-boot-impact-on-linux.pdf http://ozlabs.org/docs/uefi-secure-boot-impact-on-linux.pdf section 2.3: "This is known in the UEFI specification as the “forbidden signatures database”, and is modifiable during execution by authenticated software."

sounds 14y ago

I've never thought UEFI Secure Boot was a great idea, but Fedora paying Microsoft to get a signed boot loader feels, errrm, creepy to me. On the bright side however, Fedora's boot loader is just a signature verifying loader to boot grub2 - using _Fedora's_ PKI. That's encouraging because at an ideological level it's exploiting Microsoft's process to give Fedora control over everything downstream from their loader. The name even implies that it's a kind of workaround: "shim loader." (Shim is defined in some circles as a compatibility workaround.) I guess Fedora doesn't plan on becoming a signing authority for custom kernels, but in a pinch it could work. Please, everyone start contributing to http://coreboot.org http://coreboot.org ! [Edited for clarity.]

av500 14y ago
it does not give Fedora "control over the whole process". It's not only the bootloader that is signed, it's also kernel and modules. And if any of these is compromised, M$ can see that as a threat to a Windows installation on the same PC and revoke the "Fedora" keys. Not that M$ would have any incentive to do such a thing ever....
lucian1900 14y ago
As long as OEMs only listen to MS, coreboot will never happen. Even with UEFI, this doesn't have to be a problem.
- sounds 14y ago
  Unless I misunderstand what you mean by "will never happen," I think you should take a second look at coreboot. It's happening. It's just not on _your_ laptop, but it could be. Try it out.

saulrh 14y ago

Microsoft will be offering signing services through their sysdev portal. It's not entirely free (there's a one-off $99 fee to gain access) In other words, Microsoft won. Not only have they made Linux significantly more difficult to develop and use, they have managed to actually extract money from open-source developers. This is why MS has such a bad reputation.

InclinedPlane 14y ago
I don't get it. My reading is that MS will sign Linux distros for a lifetime fee of $100 per vendor. That doesn't sound like MS is going to be living high off the hog from those proceeds, it sounds like a reasonable fee to prevent abuse of the system. Also, as far as I can tell a user (or an OEM) can just go into their UEFI settings and turn off secure boot, then install and boot completely unsigned anything. This doesn't seem like the end of the world to me.
- slowpoke 14y ago
  >I don't get it. My reading is that MS will sign Linux distros for a lifetime fee of $100 per vendor. That's besides the point. It's that Microsoft - a software vendor - is suddenly the authority over distributing and signing keys for what amounts to a hardware lock mechanism that prevents you from doing whatever the fuck you want with your computer, all in the name of a false pretext of security. This is insanity. >Also, as far as I can tell a user (or an OEM) can just go into their UEFI settings and turn off secure boot, then install and boot completely unsigned anything. The problem is with what you've conveniently placed into parentheses - if the OEM decides to not give you the ability to turn it off, you're fucked. A hardware vendor should not have the ability to tell me what the fuck I can run off it. I'll admit that this is getting into slippery slope territory, but I can see a lot of OEMs using this "feature" because, hey, it worked for Apple - it can't be that bad⸮
  - cooldeal 14y ago
    >all in the name of a false pretext of security How is it false? Rootkits are a real danger, because they can be undetectable by any antivirus you can run. It's funny because many of same people attacking Microsoft here turn around and claim that Microsoft software is insecure and recommend you switch to OS X/Linux! >if the OEM decides to not give you the ability to turn it off, you're fucked In order to qualify for the Windows Logo, OEMs are REQUIRED by Microsoft to give the user the ability to turn it off or add their own keys. As such, UEFI software will have this feature anyway, so I seriously doubt any OEM would not do that, since they aren't saving anything and only the tech savvy will mess with the settings anyway.

gioele 14y ago

> Our first stage bootloader will be signed with a Microsoft key. It is a sad sad day.

rwmj 14y ago

So Microsoft will sign just about any bootloader for a one-off fee of $99? What's to stop me setting up a legit-looking company, writing a fake bootloader, getting it signed, then adding malware to Windows? If the key is blacklisted, I'll just sign up for another one. The whole idea of secure booting on hardware that you don't physically control is ridiculous anyway. You're trusting everything in that chain of software, from the bootloader, through the OS, through to every ring 0 driver, to not contain any exploitable bug. We know how well that worked out, just look at consoles & Android. Microsoft aren't stupid. They know this isn't going to provide real security. I think the intention is (a) prevent people easily repurposing machines to run Linux, (b) provide a sop to Big Content, (c) set expectations that you don't own the hardware you bought.

deleted 14y ago
[deleted]
tzs 14y ago
> I think the intention is (a) prevent people easily repurposing machines to run Linux Serious question: are there really many people who • know enough to take a Windows machine, obtain a Linux boot CD or boot USB drive, do whatever voodoo is required to make the computer boot from that instead of from the hard disk, and then go through the Linux install, but who cannot easily • figure out how to invoke the BIOS settings menu and change the secure boot option from "enabled" to "disabled" ? I understand that Linux is getting friendlier to non-techies, and many people report success in getting Grandma using Linux, but in almost all of these stories they installed Linux for Grandma. They did not just toss her a CD and say "try this!".
- rwmj 14y ago
  It's an extra step in the process. Plus if you're dual booting, you have to switch the BIOS back and forth every time you switch between "secure" Windows 8 and Linux.

dhx 14y ago

Matthew’s earlier article “Why UEFI secure boot is difficult for Linux” is worth reading: http://mjg59.dreamwidth.org/9844.html http://mjg59.dreamwidth.org/9844.html

josteink 14y ago

Why does a computer (a physical general computation device) need, require or trust keys from Microsoft (one singular software vendor) in the first place? If this isn't defined as monopoly-abuse, I don't know what is.

apetrovic 14y ago
Just build a computer, a physical general computation device, with a motherboard that doesn't have Windows sticker on the box (the shiny thing issued by Microsoft) and you should be fine.
- josteink 14y ago
  While that is a valid solution to the problem, it is also tippy-toing around why the problem is there in the first place. And that is what I was curious about.
zokier 14y ago
Computer doesn't require them. But your OEM has Micrsoft keys preinstalled to run the preinstalled Windows. Note this part: >While Microsoft have modified their original position and all x86 Windows machines will be required to have a firmware option to disable this or to permit users to enrol their own keys, it's not really an option to force all our users to play with hard to find firmware settings before they can run Fedora Two things can be picked from that quote: 1) If you don't want to trust MS, then put in your own keys. 2) Fedora got their bootloader signed for convenience, not because it would be required.
- krakensden 14y ago
  It's not required now, but it will be to get a Windows 8 Certified logo. Which means basically everything will have it when Windows 8 comes out.
  - tzs 14y ago
    No. The original Windows 8 logo requirements were that secure boot be enabled by default, and were silent on whether or not the OEM could provide an option to disable it. Microsoft updated the requirements to say that OEMs must provide, on x86, a way to disable it or allow users to install their own keys.

conductor 14y ago

I wonder, once every piece of motherboards are shipped with MS key, how much CPU time would be needed to factor the private key and sign anything? Some distributed piece of software running on thousands of anonymous machines should solve the problem in weeks I think, or not?

zurn 14y ago
A SSL cert vendor has a popularized writeup for 2048-bit RSA (which UEFI uses according to http://www.uefi.org/learning_center/UEFI_Plugfest_2012Q1_v3_AMI.pdf http://www.uefi.org/learning_center/UEFI_Plugfest_2012Q1_v3_...) at http://www.digicert.com/TimeTravel/math.htm http://www.digicert.com/TimeTravel/math.htm: "[...] It is therefore estimated, that standard desktop computing power would take 4,294,967,296 x 1.5 million years to break a DigiCert 2048-bit SSL certificate. Or, in other words, a little over 6.4 quadrillion years."

rcthompson 14y ago

What if you bought a new house and the bank you bought it from told you that they would be keeping your house keys and not giving you a copy? It's not the most accurate analogy, but the point is that UEFI puts a lock on the boot process, which is itself arguably a good thing, but then Microsoft and others are trying to control the keys that rightfully belong to the owner of the hardware. Or more simply, locks are not bad per se, but if you aren't allowed to have the key to a lock that you supposedly own, then that's bad.