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1// SPDX-License-Identifier: GPL-2.02/*3 * Secure boot handling.4 *5 * Copyright (C) 2013,2014 Linaro Limited6 * Roy Franz <roy.franz@linaro.org7 * Copyright (C) 2013 Red Hat, Inc.8 * Mark Salter <msalter@redhat.com>9 */10#include <linux/efi.h>11#include <asm/efi.h>12 13#include "efistub.h"14 15/* SHIM variables */16static const efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;17static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";18 19static efi_status_t get_var(efi_char16_t *name, efi_guid_t *vendor, u32 *attr,20 unsigned long *data_size, void *data)21{22 return get_efi_var(name, vendor, attr, data_size, data);23}24 25/*26 * Determine whether we're in secure boot mode.27 */28enum efi_secureboot_mode efi_get_secureboot(void)29{30 u32 attr;31 unsigned long size;32 enum efi_secureboot_mode mode;33 efi_status_t status;34 u8 moksbstate;35 36 mode = efi_get_secureboot_mode(get_var);37 if (mode == efi_secureboot_mode_unknown) {38 efi_err("Could not determine UEFI Secure Boot status.\n");39 return efi_secureboot_mode_unknown;40 }41 if (mode != efi_secureboot_mode_enabled)42 return mode;43 44 /*45 * See if a user has put the shim into insecure mode. If so, and if the46 * variable doesn't have the non-volatile attribute set, we might as47 * well honor that.48 */49 size = sizeof(moksbstate);50 status = get_efi_var(shim_MokSBState_name, &shim_guid,51 &attr, &size, &moksbstate);52 53 /* If it fails, we don't care why. Default to secure */54 if (status != EFI_SUCCESS)55 goto secure_boot_enabled;56 if (!(attr & EFI_VARIABLE_NON_VOLATILE) && moksbstate == 1)57 return efi_secureboot_mode_disabled;58 59secure_boot_enabled:60 efi_info("UEFI Secure Boot is enabled.\n");61 return efi_secureboot_mode_enabled;62}63