User: Password:
|
|
Subscribe / Log in / New account

No signed kernel, just a signed boot loader

No signed kernel, just a signed boot loader

Posted Jun 25, 2012 18:56 UTC (Mon) by jspaleta (subscriber, #50639)
In reply to: No signed kernel, just a signed boot loader by pboddie
Parent article: Details on Ubuntu's UEFI secure boot plan

The core issue here is the on-by-default requirement for consumer hardware coupled with the specs limitations which prevents a mult-vendor trust chain.

Secureboot as a concept is not a bad thing. The policy surrounding how to enable secureboot for consumer devices needs some iteration however. There is absolutely nothing wrong with an off-by-default secureboot even with the current specification and limitations. On-by-default, has some definite challenges, and MS's certification process requirements brings these challenged directly into the forefront of the discussion.

Even with an on-by-default scheme, if users can disable secureboot to regain access to a system that has been impacted by a key revocation I really don't see a fundamental problem. As long as users are not locked out of the firmware config screens to disable secureboot on the hardware they purchased, a 3rd party revocation process is best described as a very stringent notification about a potential system compromise. If users can disable secureboot they do not lose access to their systems even after a key that their current configuration requires has been revoked.

In fact I'd wager that once the security benefit is digested more widely large institutions like the US Department of Defense and the State Department and even municipal power companies will be making heavy use of secureboot with their own signing keys on a lot of critical infrastructure and even desktops and laptops...so they don't even have to implicitly trust any Vendor (including Microsoft). They'll use the firmware reconfiguration to the fullest to load their own keys on their hardware and then self-sign binaries and to control the revocation process from end-to-end.

-jef


(Log in to post comments)

No signed kernel, just a signed boot loader

Posted Jun 25, 2012 19:13 UTC (Mon) by raven667 (subscriber, #5198) [Link]

> specs limitations which prevents a mult-vendor trust chain

I'm not sure that's true, you can have many vendor and user keys loaded into the firmware but to get your key pre-loaded would require some relationship with the vendor so your hardware coverage is likely to be less than 100%, whereas all the vendors want to be able to run MS so that key is virtually guaranteed to be loaded by default.

Actual binaries can be signed by only one key though so to boot and reduce the number of boot media spins required forces you to choose which key you are going to use to sign your initial boot loader and the MS key wins on convenience there.

> Even with an on-by-default scheme, if users can disable secureboot to regain access to a system that has been impacted by a key revocation I really don't see a fundamental problem

Which is exactly the case now for x86. Win8 ARM hosts are boot locked but that's its own separate issue at this time, I don't think any Linux vendor is going to fool around with them. Just don't buy them an expect to run anything else on them (not much different that the rest of the ARM market anyway).

> companies will be making heavy use of secureboot with their own signing keys

Thats probably something they will want to do but it depends on how to sign or re-sign boot binaries. Is it possible to re-sign the Windows 8 boot loader for example and have the system not broken? Certainly this will be do-able, maybe even common, with Linux systems.

No signed kernel, just a signed boot loader

Posted Jun 26, 2012 7:27 UTC (Tue) by ssmith32 (subscriber, #72404) [Link]

You seem to have a lot of faith in municipal power companies commitment to security...

Unfortunately, regardless of the "should", there are plenty of examples to the contrary.

Whatever the original intent, in reality, UEFI's largest impact so far has been to impose a significant cost on open-source software, with the to-be-determined security benefits still vaporware..


Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds