6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ard Biesheuvel ardb+git@google.com
From: Ard Biesheuvel ardb@kernel.org
[ Commit 11078876b7a6a1b7226344fecab968945c806832 upstream ]
Currently, the EFI stub relies on DXE services in some cases to clear non-execute restrictions from page allocations that need to be executable. This is dodgy, because DXE services are not specified by UEFI but by PI, and they are not intended for consumption by OS loaders. However, no alternative existed at the time.
Now, there is a new UEFI protocol that should be used instead, so if it exists, prefer it over the DXE services calls.
Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/r/20230807162720.545787-18-ardb@kernel.org Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/firmware/efi/libstub/x86-stub.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-)
--- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -26,6 +26,7 @@ const efi_system_table_t *efi_system_tab const efi_dxe_services_table_t *efi_dxe_table; u32 image_offset __section(".data"); static efi_loaded_image_t *image = NULL; +static efi_memory_attribute_protocol_t *memattr;
static efi_status_t preserve_pci_rom_image(efi_pci_io_protocol_t *pci, struct pci_setup_rom **__rom) @@ -222,12 +223,18 @@ void efi_adjust_memory_range_protection( unsigned long rounded_start, rounded_end; unsigned long unprotect_start, unprotect_size;
- if (efi_dxe_table == NULL) - return; - rounded_start = rounddown(start, EFI_PAGE_SIZE); rounded_end = roundup(start + size, EFI_PAGE_SIZE);
+ if (memattr != NULL) { + efi_call_proto(memattr, clear_memory_attributes, rounded_start, + rounded_end - rounded_start, EFI_MEMORY_XP); + return; + } + + if (efi_dxe_table == NULL) + return; + /* * Don't modify memory region attributes, they are * already suitable, to lower the possibility to @@ -758,6 +765,7 @@ void __noreturn efi_stub_entry(efi_handl efi_system_table_t *sys_table_arg, struct boot_params *boot_params) { + efi_guid_t guid = EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID; unsigned long bzimage_addr = (unsigned long)startup_32; unsigned long buffer_start, buffer_end; struct setup_header *hdr = &boot_params->hdr; @@ -769,13 +777,18 @@ void __noreturn efi_stub_entry(efi_handl if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) efi_exit(handle, EFI_INVALID_PARAMETER);
- efi_dxe_table = get_efi_config_table(EFI_DXE_SERVICES_TABLE_GUID); - if (efi_dxe_table && - efi_dxe_table->hdr.signature != EFI_DXE_SERVICES_TABLE_SIGNATURE) { - efi_warn("Ignoring DXE services table: invalid signature\n"); - efi_dxe_table = NULL; + if (IS_ENABLED(CONFIG_EFI_DXE_MEM_ATTRIBUTES)) { + efi_dxe_table = get_efi_config_table(EFI_DXE_SERVICES_TABLE_GUID); + if (efi_dxe_table && + efi_dxe_table->hdr.signature != EFI_DXE_SERVICES_TABLE_SIGNATURE) { + efi_warn("Ignoring DXE services table: invalid signature\n"); + efi_dxe_table = NULL; + } }
+ /* grab the memory attributes protocol if it exists */ + efi_bs_call(locate_protocol, &guid, NULL, (void **)&memattr); + status = efi_setup_5level_paging(); if (status != EFI_SUCCESS) { efi_err("efi_setup_5level_paging() failed!\n");