Enable LUKS2 and Argon2 Support for Packages
Because the LUKS partition uses LUKS2 and Argon2id, support for these LUKS configurations must be enabled for all software packages that unlock the LUKS partition.
Set USE Flags
The following USE settings need to be added to /etc/portage/package.use
:
sys-apps/systemd cryptsetup
sys-boot/grub device-mapper
sys-fs/cryptsetup argon2 -static-libs
The detailed instructions to do this are available in the Handbook.
The USE flag settings for sys-fs/cryptsetup
above should not change anything
as they are the same as the package’s default USE flag settings, so they do not
need to be explicitly declared; rather, they are included for completeness.
The argon2
USE flag must be enabled for Argon2id support. The static-libs
USE flag must be disabled so cryptsetup
can be built into the initramfs by
dracut, or else the LUKS partition could not be unlocked during boot.
Add Patches for GRUB 2.06
GRUB 2.06 has limited support for LUKS2. Although code implementing partial LUKS2 support exists in this version, the bootloader files installed using the default procedure do not support LUKS2. Argon2id is not supported at all in this version either.
Luckily, after applying the following patches to GRUB 2.06, LUKS2 support can be added to the installed bootloader files automatically, and Argon2id is supported too.
-
4500-grub-2.06-runtime-memregion-alloc.patch
: A patch set that allows GRUB to allocate new consecutive and large memory chunks, which is a prerequisite for Argon2 support in GRUB. Argon2 enhances the security of LUKS by increasing the size of memory required for unlocking computations, so GRUB must be able to allocate more memory when needed. This patch set was cherry-picked from changes staged for the next GRUB release. -
5000-grub-2.06-luks2-argon2-v4.patch
: The patch set that adds Argon2 support itself to GRUB. It was submitted to the grub-devel mailing list, but the GRUB project’s maintainers have not responded with regards to it yet. -
9500-grub-AUR-improved-luks2.patch
: A patch included in thegrub-improved-luks2-git
package on the AUR, which is what the Arch Wiki’s GRUB article recommends for users seeking great LUKS2 support in GRUB. This patch allows thegrub-install
command to automatically install bootloader files with LUKS2 support.
The numbers in front of the patches’ file names are there only to control the order in which they are applied (patches with a smaller ordinal are applied first). As long as the order is maintained, these numbers’ values are arbitrary.
To apply these patches to Gentoo’s GRUB package – sys-boot/grub
, add them as
Portage user patches to
/etc/portage/patches/sys-boot/grub-2.06
. Patches at this location are
applied to all Gentoo revisions of GRUB 2.06 (-r3
, -r4
, etc.). The
following commands may be used to do this:
# mkdir -p /etc/portage/patches/sys-boot/grub-2.06
# cd /etc/portage/patches/sys-boot/grub-2.06
# curl -O https://leo3418.github.io/res/collections/gentoo-config-luks2-grub-systemd/4500-grub-2.06-runtime-memregion-alloc.patch
# curl -O https://leo3418.github.io/res/collections/gentoo-config-luks2-grub-systemd/5000-grub-2.06-luks2-argon2-v4.patch
# curl -O https://leo3418.github.io/res/collections/gentoo-config-luks2-grub-systemd/9500-grub-AUR-improved-luks2.patch
Readers who are interested in learning more about Portage’s user patch feature are welcome to read another article on this website that discusses it in depth.
Because the patch set for Argon2 support modifies the file
grub-core/Makefile.core.def
, according to the sys-boot/grub
ebuild, the GRUB_AUTOGEN
environment variable must be
set. Otherwise, any builds of the package with the patch set applied would
fail. The environment variable can be set exclusively for all Gentoo
revisions of sys-boot/grub-2.06
in file
/etc/portage/env/sys-boot/grub-2.06
:
# mkdir -p /etc/portage/env/sys-boot
# echo 'GRUB_AUTOGEN=1' >> /etc/portage/env/sys-boot/grub-2.06
New Installation Only: Initialize Portage
If a new Gentoo installation is being performed, then please follow the instructions in the following Handbook sections under the Configuring Portage chapter:
- Installing a Gentoo ebuild repository snapshot from the web
- Optional: Updating the Gentoo ebuild repository
- Reading news items
- Choosing the right profile
Rebuild Packages
First, build sys-boot/grub
with the patches applied. Before starting the
build, please make sure that in the output of emerge
,
GRUB_PLATFORMS="efi-64"
is enabled for sys-boot/grub
. In other words,
please check that efi-64
is listed without a minus sign (-
) in front of
it under GRUB_PLATFORMS
. If this is not true, the Handbook has related
instructions to fix it.
# emerge --ask --verbose sys-boot/grub
These are the packages that would be merged, in order:
Calculating dependencies... done!
[ebuild N ] sys-boot/grub-2.06-r2:2/2.06-r2::gentoo USE="device-mapper fon
ts nls themes -doc -efiemu -libzfs -mount -sdl (-test) -truetype" GRUB_PLATFORMS
="efi-64 pc -coreboot -efi-32 -emu -ieee1275 (-loongson) -multiboot -qemu (-qemu
-mips) -uboot -xen -xen-32 -xen-pvh" 8171 KiB
Total: 1 package (1 new), Size of downloads: 8171 KiB
Would you like to merge these packages? [Yes/No]
Next, update the system’s world set to apply the USE flag changes:
# emerge --ask --verbose --update --deep --newuse @world