Blame SOURCES/0126-efi-Set-image-base-address-before-jumping-to-the-PE-.patch

8e15ce
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
8e15ce
From: Javier Martinez Canillas <javierm@redhat.com>
8e15ce
Date: Thu, 23 Apr 2020 15:06:46 +0200
8e15ce
Subject: [PATCH] efi: Set image base address before jumping to the PE/COFF
8e15ce
 entry point
8e15ce
8e15ce
Upstream GRUB uses the EFI LoadImage() and StartImage() to boot the Linux
8e15ce
kernel. But our custom EFI loader that supports Secure Boot instead uses
8e15ce
the EFI handover protocol (for x86) or jumping directly to the PE/COFF
8e15ce
entry point (for aarch64).
8e15ce
8e15ce
This is done to allow the bootloader to verify the images using the shim
8e15ce
lock protocol to avoid booting untrusted binaries.
8e15ce
8e15ce
Since the bootloader loads the kernel from the boot media instead of using
8e15ce
LoadImage(), it is responsible to set the Loaded Image base address before
8e15ce
booting the kernel.
8e15ce
8e15ce
Otherwise the kernel EFI stub will complain that it was not set correctly
8e15ce
and print the following warning message:
8e15ce
8e15ce
EFI stub: ERROR: FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value
8e15ce
8e15ce
Resolves: rhbz#1814690
8e15ce
8e15ce
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
8e15ce
---
8e15ce
 grub-core/loader/efi/linux.c | 14 ++++++++++++++
8e15ce
 1 file changed, 14 insertions(+)
8e15ce
8e15ce
diff --git a/grub-core/loader/efi/linux.c b/grub-core/loader/efi/linux.c
b35c50
index 0622dfa48d..e8b9ecb17f 100644
8e15ce
--- a/grub-core/loader/efi/linux.c
8e15ce
+++ b/grub-core/loader/efi/linux.c
8e15ce
@@ -72,6 +72,7 @@ grub_err_t
8e15ce
 grub_efi_linux_boot (void *kernel_addr, grub_off_t handover_offset,
8e15ce
 		     void *kernel_params)
8e15ce
 {
8e15ce
+  grub_efi_loaded_image_t *loaded_image = NULL;
8e15ce
   handover_func hf;
8e15ce
   int offset = 0;
8e15ce
 
8e15ce
@@ -79,6 +80,19 @@ grub_efi_linux_boot (void *kernel_addr, grub_off_t handover_offset,
8e15ce
   offset = 512;
8e15ce
 #endif
8e15ce
 
8e15ce
+  /*
8e15ce
+   * Since the EFI loader is not calling the LoadImage() and StartImage()
8e15ce
+   * services for loading the kernel and booting respectively, it has to
8e15ce
+   * set the Loaded Image base address.
8e15ce
+   */
8e15ce
+  loaded_image = grub_efi_get_loaded_image (grub_efi_image_handle);
8e15ce
+  if (loaded_image)
8e15ce
+    loaded_image->image_base = kernel_addr;
8e15ce
+  else
8e15ce
+    grub_dprintf ("linux", "Loaded Image base address could not be set\n");
8e15ce
+
8e15ce
+  grub_dprintf ("linux", "kernel_addr: %p handover_offset: %p params: %p\n",
8e15ce
+		kernel_addr, (void *)(grub_efi_uintn_t)handover_offset, kernel_params);
8e15ce
   hf = (handover_func)((char *)kernel_addr + handover_offset + offset);
8e15ce
   hf (grub_efi_image_handle, grub_efi_system_table, kernel_params);
8e15ce