Commit 3c6edd90 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi: zboot: create MemoryMapped() device path for the parent if needed 



LoadImage() is supposed to install an instance of the protocol
EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL onto the loaded image's handle so
that the program can figure out where it was loaded from. The reference
implementation even does this (with a NULL protocol pointer) if the call
to LoadImage() used the source buffer and size arguments, and passed
NULL for the image device path. Hand rolled implementations of LoadImage
may behave differently, though, and so it is better to tolerate
situations where the protocol is missing. And actually, concatenating an
Offset() node to a NULL device path (as we do currently) is not great
either.

So in cases where the protocol is absent, or when it points to NULL,
construct a MemoryMapped() device node as the base node that describes
the parent image's footprint in memory.

Cc: Daan De Meyer <daandemeyer@fb.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 04419e8a

drivers/firmware/efi/libstub/zboot.c

+16 −4
Original line number Diff line number Diff line
@@ -162,6 +162,11 @@ static void append_end_node(efi_device_path_protocol_t **dp) 
asmlinkage efi_status_t __efiapi

efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab)

{

	struct efi_mem_mapped_dev_path mmdp = {

		.header.type		= EFI_DEV_HW,

		.header.sub_type	= EFI_DEV_MEM_MAPPED,

		.header.length		= sizeof(struct efi_mem_mapped_dev_path)

	};

	efi_device_path_protocol_t *parent_dp, *dpp, *lf2_dp, *li_dp;

	efi_load_file2_protocol_t zboot_load_file2;

	efi_loaded_image_t *parent, *child;
@@ -191,13 +196,20 @@ efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab) 
	status = efi_bs_call(handle_protocol, handle,

			     &LOADED_IMAGE_DEVICE_PATH_PROTOCOL_GUID,

			     (void **)&parent_dp);

	if (status != EFI_SUCCESS) {

		log(L"Failed to locate parent's loaded image device path protocol");

		return status;

	if (status != EFI_SUCCESS || parent_dp == NULL) {

		// Create a MemoryMapped() device path node to describe

		// the parent image if no device path was provided.

		mmdp.memory_type	= parent->image_code_type;

		mmdp.starting_addr	= (unsigned long)parent->image_base;

		mmdp.ending_addr	= (unsigned long)parent->image_base +

					  parent->image_size - 1;

		parent_dp = &mmdp.header;

		dp_len = sizeof(mmdp);

	} else {

		dp_len = device_path_length(parent_dp);

	}



	// Allocate some pool memory for device path protocol data

	dp_len = parent_dp ? device_path_length(parent_dp) : 0;

	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,

			     2 * (dp_len + sizeof(struct efi_rel_offset_dev_path) +

			          sizeof(struct efi_generic_dev_path)) +

include/linux/efi.h

+7 −0
Original line number Diff line number Diff line
@@ -1004,6 +1004,13 @@ struct efi_rel_offset_dev_path { 
	u64				ending_offset;

} __packed;



struct efi_mem_mapped_dev_path {

	struct efi_generic_dev_path	header;

	u32				memory_type;

	u64				starting_addr;

	u64				ending_addr;

} __packed;



struct efi_dev_path {

	union {

		struct efi_generic_dev_path	header;