grub: import phc argon2 implementation (for luks2)

Patches pulled from:
https://git.nicholasjohnson.ch/grub
This is the author of the rebased patches:
https://nicholasjohnson.ch/
(Nicholas Johnson <nick@nicholasjohnson.ch>)

However, this is a *rebase* performed by Nicholas,
based on these patches:

https://aur.archlinux.org/cgit/aur.git/tree/?h=grub-improved-luks2-git
...at revision: 1c7932d90f1f62d0fd5485c5eb8ad79fa4c2f50d

The AUR patches were based on GRUB 2.06, whereas Nicholas's
rebase is upon grub 2.12, which Libreboot currently uses.

These patches import the PHC implementation of argon2i/id
key derivation functions, seen here:
https://github.com/P-H-C/phc-winner-argon2

GRUB (upstream) does not merge these patches and probably won't,
because even though they're libre, they're not copylefted or
otherwise under GPL terms that GRUB can accept.

Therefore, we in Libreboot must maintain these from now on,
for our version of GRUB. The upshot? LUKSv2 decryption should
now work, perfectly, in GRUB!

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/resources/grub/patches/0008-Make-grub-install-work-with-Argon2.patch b/resources/grub/patches/0008-Make-grub-install-work-with-Argon2.patch
new file mode 100644
index 00000000..dc65b7a6
--- /dev/null
+++ b/resources/grub/patches/0008-Make-grub-install-work-with-Argon2.patch
@@ -0,0 +1,26 @@
+From 6c9a6625c0dc038d1bdbdc13665f40e269e86496 Mon Sep 17 00:00:00 2001
+From: Ax333l <main@axelen.xyz>
+Date: Thu, 17 Aug 2023 00:00:00 +0000
+Subject: [PATCH 6/6] Make grub-install work with Argon2
+
+Signed-off-by: Nicholas Johnson <nick@nicholasjohnson.ch>
+---
+ util/grub-install.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/util/grub-install.c b/util/grub-install.c
+index 1ad04db36..a8a3330b8 100644
+--- a/util/grub-install.c
++++ b/util/grub-install.c
+@@ -448,6 +448,8 @@ probe_mods (grub_disk_t disk)
+     {
+       grub_util_cryptodisk_get_abstraction (disk,
+ 					    push_cryptodisk_module, NULL);
++      /* HACK: always push argon2 */
++      grub_install_push_module ("argon2");
+       have_abstractions = 1;
+       have_cryptodisk = 1;
+     }
+-- 
+2.39.2
+