1/* SPDX-License-Identifier: GPL-2.0+ */
 2/*
 3 * Copyright (C) 2018 IBM Corporation
 4 */
 5#include <linux/efi.h>
 6#include <linux/module.h>
 7#include <linux/ima.h>
 8
 9extern struct boot_params boot_params;
10
11static enum efi_secureboot_mode get_sb_mode(void)
12{
13	efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
14	efi_status_t status;
15	unsigned long size;
16	u8 secboot, setupmode;
17
18	size = sizeof(secboot);
19
20	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) {
21		pr_info("ima: secureboot mode unknown, no efi\n");
22		return efi_secureboot_mode_unknown;
23	}
24
25	/* Get variable contents into buffer */
26	status = efi.get_variable(L"SecureBoot", &efi_variable_guid,
27				  NULL, &size, &secboot);
28	if (status == EFI_NOT_FOUND) {
29		pr_info("ima: secureboot mode disabled\n");
30		return efi_secureboot_mode_disabled;
31	}
32
33	if (status != EFI_SUCCESS) {
34		pr_info("ima: secureboot mode unknown\n");
35		return efi_secureboot_mode_unknown;
36	}
37
38	size = sizeof(setupmode);
39	status = efi.get_variable(L"SetupMode", &efi_variable_guid,
40				  NULL, &size, &setupmode);
41
42	if (status != EFI_SUCCESS)	/* ignore unknown SetupMode */
43		setupmode = 0;
44
45	if (secboot == 0 || setupmode == 1) {
46		pr_info("ima: secureboot mode disabled\n");
47		return efi_secureboot_mode_disabled;
48	}
49
50	pr_info("ima: secureboot mode enabled\n");
51	return efi_secureboot_mode_enabled;
52}
53
54bool arch_ima_get_secureboot(void)
55{
56	static enum efi_secureboot_mode sb_mode;
57	static bool initialized;
58
59	if (!initialized && efi_enabled(EFI_BOOT)) {
60		sb_mode = boot_params.secure_boot;
61
62		if (sb_mode == efi_secureboot_mode_unset)
63			sb_mode = get_sb_mode();
64		initialized = true;
65	}
66
67	if (sb_mode == efi_secureboot_mode_enabled)
68		return true;
69	else
70		return false;
71}
72
73/* secureboot arch rules */
74static const char * const sb_arch_rules[] = {
75#if !IS_ENABLED(CONFIG_KEXEC_SIG)
76	"appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig",
77#endif /* CONFIG_KEXEC_SIG */
78	"measure func=KEXEC_KERNEL_CHECK",
79#if !IS_ENABLED(CONFIG_MODULE_SIG)
80	"appraise func=MODULE_CHECK appraise_type=imasig",
81#endif
82	"measure func=MODULE_CHECK",
83	NULL
84};
85
86const char * const *arch_get_ima_policy(void)
87{
88	if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot()) {
89		if (IS_ENABLED(CONFIG_MODULE_SIG))
90			set_module_sig_enforced();
91		return sb_arch_rules;
92	}
93	return NULL;
94}