1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Secure boot handling.
 4 *
 5 * Copyright (C) 2013,2014 Linaro Limited
 6 *     Roy Franz <roy.franz@linaro.org
 7 * 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 the
46	 * variable doesn't have the non-volatile attribute set, we might as
47	 * 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}

 
 1/*
 2 * Secure boot handling.
 3 *
 4 * Copyright (C) 2013,2014 Linaro Limited
 5 *     Roy Franz <roy.franz@linaro.org
 6 * Copyright (C) 2013 Red Hat, Inc.
 7 *     Mark Salter <msalter@redhat.com>
 8 *
 9 * This file is part of the Linux kernel, and is made available under the
10 * terms of the GNU General Public License version 2.
11 */
12#include <linux/efi.h>
13#include <asm/efi.h>
14
15#include "efistub.h"
16
17/* BIOS variables */
18static const efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
19static const efi_char16_t efi_SecureBoot_name[] = L"SecureBoot";
20static const efi_char16_t efi_SetupMode_name[] = L"SetupMode";
21
22/* SHIM variables */
23static const efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID;
24static const efi_char16_t shim_MokSBState_name[] = L"MokSBState";
25
26#define get_efi_var(name, vendor, ...) \
27	efi_call_runtime(get_variable, \
28			 (efi_char16_t *)(name), (efi_guid_t *)(vendor), \
29			 __VA_ARGS__);
 
30
31/*
32 * Determine whether we're in secure boot mode.
33 */
34enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table_arg)
35{
36	u32 attr;
37	u8 secboot, setupmode, moksbstate;
38	unsigned long size;
 
39	efi_status_t status;
 
40
41	size = sizeof(secboot);
42	status = get_efi_var(efi_SecureBoot_name, &efi_variable_guid,
43			     NULL, &size, &secboot);
44	if (status == EFI_NOT_FOUND)
45		return efi_secureboot_mode_disabled;
46	if (status != EFI_SUCCESS)
47		goto out_efi_err;
48
49	size = sizeof(setupmode);
50	status = get_efi_var(efi_SetupMode_name, &efi_variable_guid,
51			     NULL, &size, &setupmode);
52	if (status != EFI_SUCCESS)
53		goto out_efi_err;
54
55	if (secboot == 0 || setupmode == 1)
56		return efi_secureboot_mode_disabled;
57
58	/*
59	 * See if a user has put the shim into insecure mode. If so, and if the
60	 * variable doesn't have the runtime attribute set, we might as well
61	 * honor that.
62	 */
63	size = sizeof(moksbstate);
64	status = get_efi_var(shim_MokSBState_name, &shim_guid,
65			     &attr, &size, &moksbstate);
66
67	/* If it fails, we don't care why. Default to secure */
68	if (status != EFI_SUCCESS)
69		goto secure_boot_enabled;
70	if (!(attr & EFI_VARIABLE_RUNTIME_ACCESS) && moksbstate == 1)
71		return efi_secureboot_mode_disabled;
72
73secure_boot_enabled:
74	pr_efi(sys_table_arg, "UEFI Secure Boot is enabled.\n");
75	return efi_secureboot_mode_enabled;
76
77out_efi_err:
78	pr_efi_err(sys_table_arg, "Could not determine UEFI Secure Boot status.\n");
79	return efi_secureboot_mode_unknown;
80}