From 03eea19c19b52851002654c2818b765d4aa42894 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Fri, 5 May 2023 12:51:09 +0100 Subject: [efi] Allow currently selected image to be opened as "grub*.efi" Versions 15.4 and earlier of the UEFI shim are incapable of correctly parsing the command line in order to extract the second stage loader filename, and will always attempt to load "grubx64.efi" or equivalent. Versions 15.3 and later of the UEFI shim are currently incapable of loading a Linux kernel directly anyway, since the kernel does not include SBAT metadata. These versions will require a genuine shim-signed GRUB binary to be used as a crutch to assist shim in loading a Linux kernel. This leaves versions 15.2 and earlier of the UEFI shim (as currently used in e.g. RHEL7) as being capable of directly loading a Linux kernel, but incorrectly attempting to load it using the filename "grubx64.efi" or equivalent. To support the bugs in these older versions of the UEFI shim, allow the currently selected image to be opened via any filename of the form "grub*.efi". Signed-off-by: Michael Brown --- src/interface/efi/efi_file.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/src/interface/efi/efi_file.c b/src/interface/efi/efi_file.c index 673f902d5..266de4a6c 100644 --- a/src/interface/efi/efi_file.c +++ b/src/interface/efi/efi_file.c @@ -374,6 +374,7 @@ efi_file_open ( EFI_FILE_PROTOCOL *this, EFI_FILE_PROTOCOL **new, char buf[ wcslen ( wname ) + 1 /* NUL */ ]; struct image *image; char *name; + char *sep; /* Convert name to ASCII */ snprintf ( buf, sizeof ( buf ), "%ls", wname ); @@ -413,6 +414,16 @@ efi_file_open ( EFI_FILE_PROTOCOL *this, EFI_FILE_PROTOCOL **new, new ); } + /* Allow currently selected image to be opened as "grub*.efi", + * to work around buggy versions of the UEFI shim. + */ + if ( ( strncasecmp ( name, "grub", 4 ) == 0 ) && + ( ( sep = strrchr ( name, '.' ) ) != NULL ) && + ( strcasecmp ( sep, ".efi" ) == 0 ) && + ( ( image = image_find_selected() ) != NULL ) ) { + return efi_file_open_image ( image, wname, new ); + } + DBGC ( file, "EFIFILE %ls does not exist\n", wname ); return EFI_NOT_FOUND; } -- cgit