From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas Date: Thu, 23 Apr 2020 15:06:46 +0200 Subject: [PATCH] efi: Set image base address before jumping to the PE/COFF entry point Upstream GRUB uses the EFI LoadImage() and StartImage() to boot the Linux kernel. But our custom EFI loader that supports Secure Boot instead uses the EFI handover protocol (for x86) or jumping directly to the PE/COFF entry point (for aarch64). This is done to allow the bootloader to verify the images using the shim lock protocol to avoid booting untrusted binaries. Since the bootloader loads the kernel from the boot media instead of using LoadImage(), it is responsible to set the Loaded Image base address before booting the kernel. Otherwise the kernel EFI stub will complain that it was not set correctly and print the following warning message: EFI stub: ERROR: FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value Resolves: rhbz#1814690 Signed-off-by: Javier Martinez Canillas --- grub-core/loader/efi/linux.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/grub-core/loader/efi/linux.c b/grub-core/loader/efi/linux.c index 0622dfa48..e8b9ecb17 100644 --- a/grub-core/loader/efi/linux.c +++ b/grub-core/loader/efi/linux.c @@ -72,6 +72,7 @@ grub_err_t grub_efi_linux_boot (void *kernel_addr, grub_off_t handover_offset, void *kernel_params) { + grub_efi_loaded_image_t *loaded_image = NULL; handover_func hf; int offset = 0; @@ -79,6 +80,19 @@ grub_efi_linux_boot (void *kernel_addr, grub_off_t handover_offset, offset = 512; #endif + /* + * Since the EFI loader is not calling the LoadImage() and StartImage() + * services for loading the kernel and booting respectively, it has to + * set the Loaded Image base address. + */ + loaded_image = grub_efi_get_loaded_image (grub_efi_image_handle); + if (loaded_image) + loaded_image->image_base = kernel_addr; + else + grub_dprintf ("linux", "Loaded Image base address could not be set\n"); + + grub_dprintf ("linux", "kernel_addr: %p handover_offset: %p params: %p\n", + kernel_addr, (void *)(grub_efi_uintn_t)handover_offset, kernel_params); hf = (handover_func)((char *)kernel_addr + handover_offset + offset); hf (grub_efi_image_handle, grub_efi_system_table, kernel_params);