[SECURITY PATCH 005/117] efi: Lockdown the GRUB when the UEFI Secure Boot is enabled

[Daniel Kiper]

From: Javier Martinez Canillas <javierm@redhat.com>

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 b683bec5a..133346509 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>
@@ -40,8 +41,15 @@ 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);
-- 
2.11.0