On Di, 09.05.23 15:04, Chris Murphy (lists(a)colorremedies.com) wrote:
> This makese no sense. If you want /boot to just be a subvolume
> rootfs btrfs, then this would imply it's also covered by the same
> security choices, i.e. encryption. We want to bind that sooner or
> later to things like TPM2, FIDO2, PKCS11. And that's simply not
> feasible from a boot loader environment.
Windows and macOS do this, so it is feasible, the question is what
are the consequences of this and are we willing to live with them?
They focus on a much more limited set of functionality.
Also, are you volunteering to implement and maintain a full LUKS2, TPM2,
FIDO2 and PKCS11 stack in UEFI mode? Good luck, man! And it's not
getting any simpler. Next thing coming up is probably PassKey support,
which means networking support. That's going to be fun in UEFI to support!
I mean, these things tend to grow and become more complicated over
time, and if you avoid Linux userspace then you make your life
impossibly hard. And I really don't see Chris Murphy stepping up and
maintaining that mess. Or are you?
As someone who actually occasionally writes UEFI code: ffs, give up on
the idea to reimplement complex auth protocols in UEFI mode! You want
to do *less* stuff in UEFI, not pile on and pile on. Grub's reputation
suffered because they are basically reimplementing a crappy version of
Linux in their boot loader. Get yourself out of that Grub mindset, man!
This idea appears so "out there" to me, I am sorry, but I somehow
can't believe you seriously are proposing this.
One obvious consequence, it further creates dependency on a single
bootloader, GRUB. Or we need an independent project that provides an
EFI program for unlocking LUKS volumes within the pre-boot
environment, thus making plaintext view available to any bootloader.
Sorry, this is *such* *a* *bad* *idea*.
> Hence, the place the kernel is loaded from (regardless if you
> it /efi or /boot or /boot/efi, and regardless what fs it is) must
> be accessible from the boot loader easily, without requiring
> implementation of TPM2/FIDO2/PKCS11 hookup in the boot loader.
I understand that might be difficult and something we don't want to
do for resource reasons, but there isn't a technical impediment for
Well, that's true, you can hack anything up that a Turing machine can
execute and also run it in UEFI mode, but I seriously hope that you
are not actually suggesting this.
FAT isn't resizable. The growth requirement for /boot is greater
some use cases more than others, so there is pressure building
because it will create waste for some use cases and
underprovisioning in other use cases. Those unverprovisioned being
told they can't upgrade but need to reprovision to solve this is
If you don't want to resize VFAT and XBOOTLDR is not enough to address
this problem we can relatively easily extend XBOOTLDR to allow more than one
additional such partition we can search through. The code in the boot
loader is relatively straightforward. The limiting factor is more
figuring out where to mount those.
But seriously, you are making up synthetic probems. If ESP is too
small add a large XBOOTLDR and I am pretty sure we'll be fine for a
long long time before this comes an issue again. So long in fact it
might never become.
Right. Hence Linux Boot. Dump all the toy drivers in favor of real
ones. And a real user space.
I mean you understand that this just adds another chain to the boot
process? if you do what you are proposing then you need to build a
kernel that supports all that, i.e. all the complex storage, graphics
and so on that you want to boot from, and thus you'll also have alrge
images, and then what did you gain? You ave to put that in the ESP
too, and the size limits still apply. It's illusionary to believe that
the size constraints for a kernel + drivers + complex storage stack +
crypto stack + auth stack would not apply to kernel that just runs in
uefi mode instead of native mode...
Lennart Poettering, Berlin