The creator of systemd (Lennart Poettering) has recently created a new company dedicated to bringing hardware attestation to open source software.
What might this entail? A previous blog post could provide some clues:
So, let’s see how I would build a desktop OS. The trust chain matters, from the boot loader all the way to the apps. This means all code that is run must be cryptographically validated before it is run. This is in fact where big distributions currently fail pretty badly. This is a fault of current Linux distributions though, not of SecureBoot in general.
If this technology is successful, the end result could be that we would see our Linux laptops one day being as locked down as an Iphone or Android device.
There are lots of others who are equally concerned about this possibility: https://news.ycombinator.com/item?id=46784572
If the end user can arbitrarily sign code themselves that is bootable then it kind of defeats the purpose of secure boot.
The whole idea is that it makes it impossible to start if the chain of trust is broken.
It keeps someone from booting code that hasn’t been signed with my key. That’s the whole point of secure boot. If someone else has the key, then it’s not secure anymore.
The chain of trust starts with the owner of the hardware, not some random corporation that happens to make an OS. The owner can, if they wish, outsource the root of the chain of trust to a corporation, but that should be an active decision on their part, not something that happens just because the hardware was shipped with some random OS preloaded.
The thing is in such a case secureboot doesn’t help and is unnecessary. Secureboot only does anything for the concept of “trusted suppliers”.
If the system has available signing keys for itself, well, hypothetical malware could sign itself using those same keys The OS security mechanisms are the only things protecting that, and in which case the signature validation is redundant.
You can have trusted boot, e.g. LUKS volume sealed to TPM PCRs, but secureboot just doesnt make sense as a mechanism for a user to only trust themselves.
Thing is, that means you don’t really own the hardware that you buy, because a corporation is dictating what you can do with it even though it doesn’t belong to them. Most of us consider that unacceptable.
You’re arguing for protecting the PC from malicious changes made by you, the owner.
This is corporate speak. Yes, it would make sense to lock down a PC like that in a corporate setting.
For private use, the point is to secure the PC against malicious changes made by other people.
In this case, signing code yourself is perfectly fine.
They can & it doesn’t. They can change the platform key to become the platform owner & control the public keys they keep in the code signing databases. Secure Boot gives the platform owner control over authorized code signers of boot processes.