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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Trying to get secure boot + full disk encyrption + bootable timeshift backups working. How to make grub verify nothing? (self.linux)

submitted 1 year ago by moonpiedumplings to c/[email protected]

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So basically, my setup has everything encrypted except /boot/efi. This means that /boot/grub is encrypted, along with my kernels.

I am now attempting to get secure boot setup, to lock some stuff, down, but I encountered this issue: https://bbs.archlinux.org/viewtopic.php?id=282076

Now I could sign the font files... but I don't want to. Font files and grub config are located under /boot/grub, and therefore encrypted. An attacker doing something like removing my hard drive would not be able to modify them.

I don't want to go through the effort of encrypting font files, does anyone know if there is a version of grub that doesn't do this?

Actually, preferably, I would like a version of grub that doesn't verify ANYTHING. Since everything but grub's efi file is encrypted, it would be so much simpler to only do secure boot for that.

And yes, I do understand there are security benefits to being able to prevent an attacker that has gained some level of running access to do something like replacing your kernel. But I'm less concerned about that vector of attack, I would simply like to make it so that my laptops aren't affected by evil maid attacks, without losing benefits from timeshift or whatnot.

I found the specific commit where grub enforces verification of font files: https://github.com/rhboot/grub2/commit/539662956ad787fffa662720a67c98c217d78128

But I don't really feel interested in creating and maintaining my own fork of grub, and I am wondering if someone has already done that.

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[–] [email protected] 4 points 1 year ago* (last edited 1 year ago) (1 children)

If you're going for secure boot, I'd advise against GRUB.
Use an UKI, dm-verity and get one part of your disk encryption key from your TPM 2.0 (choose PCRs carefully). Is that not compatible with timeshift?
Also see safeboot.dev, even if that's just for Ubuntu 20.04.

[–] moonpiedumplings 2 points 1 year ago

Any setup where the kernels aren't stored on the btrfs root does not give bootable timeshift snapshots. This includes UKI.