From a255fd33e08015335aeac619348536b5fda8303e Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Mon, 28 Sep 2020 20:08:29 +0200
Subject: [PATCH 11/46] efi: Lockdown the GRUB when the UEFI Secure Boot is
 enabled

If the UEFI Secure Boot is enabled then the GRUB must be locked down
to prevent executing code that can potentially be used to subvert its
verification mechanisms.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 grub-core/kern/efi/init.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/grub-core/kern/efi/init.c b/grub-core/kern/efi/init.c
index 9c143eed7..08ef2b8f4 100644
--- a/grub-core/kern/efi/init.c
+++ b/grub-core/kern/efi/init.c
@@ -21,6 +21,7 @@
 #include <grub/efi/console.h>
 #include <grub/efi/disk.h>
 #include <grub/efi/sb.h>
+#include <grub/lockdown.h>
 #include <grub/term.h>
 #include <grub/misc.h>
 #include <grub/env.h>
@@ -41,8 +42,15 @@ grub_efi_init (void)
   /* Initialize the memory management system.  */
   grub_efi_mm_init ();
 
-  /* Register the shim_lock verifier if UEFI Secure Boot is enabled. */
-  grub_shim_lock_verifier_setup ();
+  /*
+   * Lockdown the GRUB and register the shim_lock verifier
+   * if the UEFI Secure Boot is enabled.
+   */
+  if (grub_efi_get_secureboot () == GRUB_EFI_SECUREBOOT_MODE_ENABLED)
+    {
+      grub_lockdown ();
+      grub_shim_lock_verifier_setup ();
+    }
 
   efi_call_4 (grub_efi_system_table->boot_services->set_watchdog_timer,
 	      0, 0, 0, NULL);
-- 
2.26.2