From db1d70f2f3039e9fad1ad18bd466799d76b1ccc3 Mon Sep 17 00:00:00 2001 From: Glenn Washburn Date: Wed, 31 May 2023 23:16:26 -0500 Subject: [PATCH] loader/efi/chainloader: Do not require a $root visible to EFI firmware when chainloading The EFI chainloader checks that a device path can be created for the $root device before allowing chainloading to a given file. This is probably to ensure that the given file can be accessed and loaded by the firmware. However, since GRUB is loading the image itself, the firmware need not be able to access the file location of the image. So remove this check. Also, this fixes an issue where chainloading an image file on a location that is accessible by the firmware, e.g. (hd0,1)/efi/boot.efi, would fail when root is a location inaccessible by the firmware, e.g. memdisk. Use GRUB_EFI_BYTES_TO_PAGES() instead of doing the calculation explicitly. Add comment noting the section where the load options for the chainloaded EFI application is constructed. Signed-off-by: Glenn Washburn Reviewed-by: Ard Biesheuvel Reviewed-by: Daniel Kiper --- grub-core/loader/efi/chainloader.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c index 1759af632..1de98f783 100644 --- a/grub-core/loader/efi/chainloader.c +++ b/grub-core/loader/efi/chainloader.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -241,10 +242,9 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)), /* Get the root device's device path. */ dev = grub_device_open (0); - if (! dev) - goto fail; - - if (dev->disk) + if (dev == NULL) + ; + else if (dev->disk) dev_handle = grub_efidisk_get_device_handle (dev->disk); else if (dev->net && dev->net->server) { @@ -267,18 +267,15 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)), if (dev_handle) dp = grub_efi_get_device_path (dev_handle); - if (! dp) + if (dp != NULL) { - grub_error (GRUB_ERR_BAD_DEVICE, "not a valid root device"); - goto fail; - } - - file_path = make_file_path (dp, filename); - if (! file_path) - goto fail; + file_path = make_file_path (dp, filename); + if (file_path == NULL) + goto fail; - grub_printf ("file path: "); - grub_efi_print_device_path (file_path); + grub_printf ("file path: "); + grub_efi_print_device_path (file_path); + } size = grub_file_size (file); if (!size) @@ -287,7 +284,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)), filename); goto fail; } - pages = (((grub_efi_uintn_t) size + ((1 << 12) - 1)) >> 12); + pages = (grub_efi_uintn_t) GRUB_EFI_BYTES_TO_PAGES (size); status = b->allocate_pages (GRUB_EFI_ALLOCATE_ANY_PAGES, GRUB_EFI_LOADER_CODE, @@ -370,6 +367,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)), } loaded_image->device_handle = dev_handle; + /* Build load options with arguments from chainloader command line. */ if (argc > 1) { int i, len; -- 2.47.2