One addition with LUKS2 was support of the key derival function Argon2
in addition to the previously supported PBKDF2 algortihm. In order to
ease getting in initial support for LUKS2, we only reused infrastructure
to support LUKS2 with PBKDF2, but left out Argon2.

This commit now introduces support for Argon2 to enable decryption of
LUKS2 partitions using this key derival function. As the code for Argon2
has been added in a previous commit in this series, adding support is
now trivial.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 Makefile.util.def           |  6 +++++-
 grub-core/Makefile.core.def |  2 +-
 grub-core/disk/luks2.c      | 13 +++++++++++--
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/Makefile.util.def b/Makefile.util.def
index f8b356cc1..39fe9cb7c 100644
--- a/Makefile.util.def
+++ b/Makefile.util.def
@@ -3,7 +3,7 @@ AutoGen definitions Makefile.tpl;
 library = {
   name = libgrubkern.a;
   cflags = '$(CFLAGS_GNULIB)';
-  cppflags = '$(CPPFLAGS_GNULIB) -I$(srcdir)/grub-core/lib/json';
+  cppflags = '$(CPPFLAGS_GNULIB) -I$(srcdir)/grub-core/lib/json -I$(srcdir)/grub-core/lib/argon2';
 
   common = util/misc.c;
   common = grub-core/kern/command.c;
@@ -36,6 +36,10 @@ library = {
   common = grub-core/kern/misc.c;
   common = grub-core/kern/partition.c;
   common = grub-core/lib/crypto.c;
+  common = grub-core/lib/argon2/argon2.c;
+  common = grub-core/lib/argon2/core.c;
+  common = grub-core/lib/argon2/ref.c;
+  common = grub-core/lib/argon2/blake2/blake2b.c;
   common = grub-core/lib/json/json.c;
   common = grub-core/disk/luks.c;
   common = grub-core/disk/luks2.c;
diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 3a004e88c..e5e5b216b 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -1197,7 +1197,7 @@ module = {
   common = disk/luks2.c;
   common = lib/gnulib/base64.c;
   cflags = '$(CFLAGS_POSIX) $(CFLAGS_GNULIB)';
-  cppflags = '$(CPPFLAGS_POSIX) $(CPPFLAGS_GNULIB) -I$(srcdir)/lib/json';
+  cppflags = '$(CPPFLAGS_POSIX) $(CPPFLAGS_GNULIB) -I$(srcdir)/lib/json -I$(srcdir)/lib/argon2';
 };
 
 module = {
diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index 02822c777..2ec0d4116 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -27,6 +27,7 @@
 #include <grub/partition.h>
 #include <grub/i18n.h>
 
+#include <argon2.h>
 #include <base64.h>
 #include <json.h>
 
@@ -448,8 +449,16 @@ luks2_decrypt_key (grub_uint8_t *out_key,
     {
       case LUKS2_KDF_TYPE_ARGON2I:
       case LUKS2_KDF_TYPE_ARGON2ID:
-	ret = grub_error (GRUB_ERR_BAD_ARGUMENT, "Argon2 not supported");
-	goto err;
+	ret = argon2_hash (k->kdf.u.argon2.time, k->kdf.u.argon2.memory, k->kdf.u.argon2.cpus,
+			   passphrase, passphraselen, salt, saltlen, area_key, k->area.key_size,
+			   k->kdf.type == LUKS2_KDF_TYPE_ARGON2I ? Argon2_i : Argon2_id,
+			   ARGON2_VERSION_NUMBER);
+        if (ret)
+	  {
+	    grub_dprintf ("luks2", "Argon2 failed: %s\n", argon2_error_message (ret));
+	    goto err;
+	  }
+        break;
       case LUKS2_KDF_TYPE_PBKDF2:
 	hash = grub_crypto_lookup_md_by_name (k->kdf.u.pbkdf2.hash);
 	if (!hash)
-- 
2.32.0