[PATCH v2 1/4] efi: Load env block from GRUB_ENV EFI variable in early init

[Glenn Washburn]

From: Peter Jones <pjo...@redhat.com>

This allows setting GRUB variables before any user interaction or GRUB
script can run. It is primarily intended to be used to turn on early
debugging.

Signed-off-by: Peter Jones <pjo...@redhat.com>
Replace grub_efi_guid_t -> grub_guid_t
Signed-off-by: Glenn Washburn <developm...@efficientek.com>
---
 grub-core/Makefile.core.def |  1 +
 grub-core/kern/efi/init.c   | 31 +++++++++++++++++++++++++++++++
 include/grub/efi/efi.h      |  5 +++++
 3 files changed, 37 insertions(+)

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 063ef5dd7801..5699736dad20 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -219,6 +219,7 @@ kernel = {
   efi = kern/efi/acpi.c;
   efi = kern/efi/sb.c;
   efi = kern/lockdown.c;
+  efi = lib/envblk.c;
   i386_coreboot = kern/i386/pc/acpi.c;
   i386_multiboot = kern/i386/pc/acpi.c;
   i386_coreboot = kern/acpi.c;
diff --git a/grub-core/kern/efi/init.c b/grub-core/kern/efi/init.c
index 1637077e1e96..2da6036129a1 100644
--- a/grub-core/kern/efi/init.c
+++ b/grub-core/kern/efi/init.c
@@ -28,8 +28,11 @@
 #include <grub/env.h>
 #include <grub/mm.h>
 #include <grub/kernel.h>
+
 #include <grub/stack_protector.h>
 
+#include <grub/lib/envblk.h>
+
 #ifdef GRUB_STACK_PROTECTOR
 
 static grub_efi_char16_t stack_chk_fail_msg[] =
@@ -94,6 +97,31 @@ grub_stack_protector_init (void)
 
 grub_addr_t grub_modbase;
 
+/* Helper for grub_efi_env_init */
+static int
+set_var (const char *name, const char *value,
+        void *whitelist __attribute__((__unused__)))
+{
+  grub_env_set (name, value);
+  return 0;
+}
+
+static void
+grub_efi_env_init (void)
+{
+  grub_guid_t efi_grub_guid = GRUB_EFI_GRUB_VARIABLE_GUID;
+  struct grub_envblk envblk_s = { NULL, 0 };
+  grub_envblk_t envblk = &envblk_s;
+
+  grub_efi_get_variable ("GRUB_ENV", &efi_grub_guid, &envblk_s.size,
+                         (void **) &envblk_s.buf);
+  if (envblk_s.buf == NULL || envblk_s.size < 1)
+    return;
+
+  grub_envblk_iterate (envblk, NULL, set_var);
+  grub_free (envblk_s.buf);
+}
+
 void
 grub_efi_init (void)
 {
@@ -105,6 +133,9 @@ grub_efi_init (void)
   /* Initialize the memory management system.  */
   grub_efi_mm_init ();
 
+  /* Populate environment with variables from EFI envblk, if it exists.  */
+  grub_efi_env_init ();
+
   /*
    * Lockdown the GRUB and register the shim_lock verifier
    * if the UEFI Secure Boot is enabled.
diff --git a/include/grub/efi/efi.h b/include/grub/efi/efi.h
index a5cd99e5afa9..3edf44dbda49 100644
--- a/include/grub/efi/efi.h
+++ b/include/grub/efi/efi.h
@@ -25,6 +25,11 @@
 #include <grub/efi/api.h>
 #include <grub/efi/pe32.h>
 
+#define GRUB_EFI_GRUB_VARIABLE_GUID \
+  { 0x91376aff, 0xcba6, 0x42be, \
+    { 0x94, 0x9d, 0x06, 0xfd, 0xe8, 0x11, 0x28, 0xe8 } \
+  }
+
 #define GRUB_LINUX_ARM_MAGIC_SIGNATURE 0x016f2818
 
 struct linux_arch_kernel_header {
-- 
2.34.1


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