Commit 9cf42bca authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi: libstub: use EFI_LOADER_CODE region when moving the kernel in memory 



The EFI spec is not very clear about which permissions are being given
when allocating pages of a certain type. However, it is quite obvious
that EFI_LOADER_CODE is more likely to permit execution than
EFI_LOADER_DATA, which becomes relevant once we permit booting the
kernel proper with the firmware's 1:1 mapping still active.

Ostensibly, recent systems such as the Surface Pro X grant executable
permissions to EFI_LOADER_CODE regions but not EFI_LOADER_DATA regions.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 97712289

drivers/firmware/efi/libstub/alignedmem.c

+3 −2
Original line number Diff line number Diff line
@@ -22,7 +22,8 @@ 
 * Return:	status code

 */

efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,

					unsigned long max, unsigned long align)

					unsigned long max, unsigned long align,

					int memory_type)

{

	efi_physical_addr_t alloc_addr;

	efi_status_t status;
@@ -36,7 +37,7 @@ efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr, 
	slack = align / EFI_PAGE_SIZE - 1;



	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,

			     EFI_LOADER_DATA, size / EFI_PAGE_SIZE + slack,

			     memory_type, size / EFI_PAGE_SIZE + slack,

			     &alloc_addr);

	if (status != EFI_SUCCESS)

		return status;

drivers/firmware/efi/libstub/arm64-stub.c

+4 −2
Original line number Diff line number Diff line
@@ -102,7 +102,8 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, 
		 * locate the kernel at a randomized offset in physical memory.

		 */

		status = efi_random_alloc(*reserve_size, min_kimg_align,

					  reserve_addr, phys_seed);

					  reserve_addr, phys_seed,

					  EFI_LOADER_CODE);

		if (status != EFI_SUCCESS)

			efi_warn("efi_random_alloc() failed: 0x%lx\n", status);

	} else {
@@ -123,7 +124,8 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, 
		}



		status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,

						    ULONG_MAX, min_kimg_align);

						    ULONG_MAX, min_kimg_align,

						    EFI_LOADER_CODE);



		if (status != EFI_SUCCESS) {

			efi_err("Failed to relocate kernel\n");

drivers/firmware/efi/libstub/efistub.h

+4 −2
Original line number Diff line number Diff line
@@ -880,7 +880,8 @@ void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, 
efi_status_t efi_get_random_bytes(unsigned long size, u8 *out);



efi_status_t efi_random_alloc(unsigned long size, unsigned long align,

			      unsigned long *addr, unsigned long random_seed);

			      unsigned long *addr, unsigned long random_seed,

			      int memory_type);



efi_status_t check_platform_features(void);
@@ -905,7 +906,8 @@ efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr, 
				unsigned long max);



efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,

					unsigned long max, unsigned long align);

					unsigned long max, unsigned long align,

					int memory_type);



efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,

				 unsigned long *addr, unsigned long min);

drivers/firmware/efi/libstub/mem.c

+2 −1
Original line number Diff line number Diff line
@@ -91,7 +91,8 @@ efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr, 


	if (EFI_ALLOC_ALIGN > EFI_PAGE_SIZE)

		return efi_allocate_pages_aligned(size, addr, max,

						  EFI_ALLOC_ALIGN);

						  EFI_ALLOC_ALIGN,

						  EFI_LOADER_DATA);



	alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;

	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,

drivers/firmware/efi/libstub/randomalloc.c

+3 −2
Original line number Diff line number Diff line
@@ -53,7 +53,8 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md, 
efi_status_t efi_random_alloc(unsigned long size,

			      unsigned long align,

			      unsigned long *addr,

			      unsigned long random_seed)

			      unsigned long random_seed,

			      int memory_type)

{

	unsigned long total_slots = 0, target_slot;

	unsigned long total_mirrored_slots = 0;
@@ -118,7 +119,7 @@ efi_status_t efi_random_alloc(unsigned long size, 
		pages = size / EFI_PAGE_SIZE;



		status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,

				     EFI_LOADER_DATA, pages, &target);

				     memory_type, pages, &target);

		if (status == EFI_SUCCESS)

			*addr = target;

		break;