> This means for example, that an encrypted system must use an ext4 /boot partition; it is no longer possible to encrypt the /boot partition.
So, they want to let attackers modify /boot, including grub.conf and the kernel command line? This is better? Look at all these fun knobs attackers will be able to turn!
https://www.kernel.org/doc/Documentation/x86/x86_64/boot-opt...
This lets you disable machine check exceptions + the iommu. That means it'll force people to use a configuration that lets attackers stick a memory probe hardware device into the system + bypass a bunch of hardware security checks. Nice!
I also found module.sig_enforce which lets the attacker disable kernel module signature verification. Sadly, I couldn't find anything that lets you directly load a kernel module from /boot.
However, init.rd lives in /boot. I wonder if its signature is verified or not. At the very least, this approach implies that attackers can piecemeal downgrade stuff early in the boot process.
https://uapi-group.org/specifications/specs/unified_kernel_i...
On a more serious note, grub is ancient bloatware, it is way overcomplicated for what it does, it's asking to be replaced by systemd-boot distro-wide.
Look at Apple and Microsoft's bootloaders, they are dead simple and have barely changed in 20 years, it makes you wonder how the hell grub was even conceived. It has config files for config files.
grub tries to do the kitchen sink. But we live in a UEFI world now. Boot is simple. None of that is necessary anymore.
I'm wondering how much was interop with trying to boot multiple operating systems off the same disk?
https://github.com/jeffv03/yaboot/blob/master/ybin/ybin#L902
Surely some user editable data has to be stored in plaintext to be able to boot a system? Does grub.cfg need to be signed by the trust chain to be able to boot?
The only major downside is that you need to trust the hardware manufacturer (and their FIPS certification), which is fine for my purposes, but might not be fine for state secrets or extremely valuable trade secrets.
But at that point why even encrypt boot and not use something like a signed UKI for decrypting the rest of the disk? That way at least you only have the kernel, its modules and userspace (the initrd usually being a subset of the actual system) as bug/exploit surface instead of also including GRUB and all its modules ontop of that.
...man, when did Ubuntu start losing every battle they fought?
Consider devuan for your next machine. I've switched almost all my linux boxes to it, and it's great.
