blob: 6224cdbc96697d71cf040fd2e5b25abe1d93c012 [file] [log] [blame]
* TPM handling.
* Copyright (C) 2016 CoreOS, Inc
* Copyright (C) 2017 Google, Inc.
* Matthew Garrett <>
* This file is part of the Linux kernel, and is made available under the
* terms of the GNU General Public License version 2.
#include <linux/efi.h>
#include <asm/efi.h>
#include "efistub.h"
static const efi_char16_t efi_MemoryOverWriteRequest_name[] = {
'M', 'e', 'm', 'o', 'r', 'y', 'O', 'v', 'e', 'r', 'w', 'r', 'i', 't',
'e', 'R', 'e', 'q', 'u', 'e', 's', 't', 'C', 'o', 'n', 't', 'r', 'o',
'l', 0
EFI_GUID(0xe20939be, 0x32d4, 0x41be, 0xa1, 0x50, 0x89, 0x7f, 0x85, 0xd4, 0x98, 0x29)
#define get_efi_var(name, vendor, ...) \
efi_call_runtime(get_variable, \
(efi_char16_t *)(name), (efi_guid_t *)(vendor), \
#define set_efi_var(name, vendor, ...) \
efi_call_runtime(set_variable, \
(efi_char16_t *)(name), (efi_guid_t *)(vendor), \
* Enable reboot attack mitigation. This requests that the firmware clear the
* RAM on next reboot before proceeding with boot, ensuring that any secrets
* are cleared. If userland has ensured that all secrets have been removed
* from RAM before reboot it can simply reset this variable.
void efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg)
u8 val = 1;
efi_guid_t var_guid = MEMORY_ONLY_RESET_CONTROL_GUID;
efi_status_t status;
unsigned long datasize = 0;
status = get_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
NULL, &datasize, NULL);
if (status == EFI_NOT_FOUND)
set_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
EFI_VARIABLE_RUNTIME_ACCESS, sizeof(val), &val);