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_char16_t efi_SecureBoot_name[] = L"SecureBoot";
14	efi_char16_t efi_SetupMode_name[] = L"SecureBoot";
15	efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
16	efi_status_t status;
17	unsigned long size;
18	u8 secboot, setupmode;
19
20	size = sizeof(secboot);
21
22	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
23		pr_info("ima: secureboot mode unknown, no efi\n");
24		return efi_secureboot_mode_unknown;
25	}
26
27	/* Get variable contents into buffer */
28	status = efi.get_variable(efi_SecureBoot_name, &efi_variable_guid,
29				  NULL, &size, &secboot);
30	if (status == EFI_NOT_FOUND) {
31		pr_info("ima: secureboot mode disabled\n");
32		return efi_secureboot_mode_disabled;
33	}
34
35	if (status != EFI_SUCCESS) {
36		pr_info("ima: secureboot mode unknown\n");
37		return efi_secureboot_mode_unknown;
38	}
39
40	size = sizeof(setupmode);
41	status = efi.get_variable(efi_SetupMode_name, &efi_variable_guid,
42				  NULL, &size, &setupmode);
43
44	if (status != EFI_SUCCESS)	/* ignore unknown SetupMode */
45		setupmode = 0;
46
47	if (secboot == 0 || setupmode == 1) {
48		pr_info("ima: secureboot mode disabled\n");
49		return efi_secureboot_mode_disabled;
50	}
51
52	pr_info("ima: secureboot mode enabled\n");
53	return efi_secureboot_mode_enabled;
54}
55
56bool arch_ima_get_secureboot(void)
57{
58	static enum efi_secureboot_mode sb_mode;
59	static bool initialized;
60
61	if (!initialized && efi_enabled(EFI_BOOT)) {
62		sb_mode = boot_params.secure_boot;
63
64		if (sb_mode == efi_secureboot_mode_unset)
65			sb_mode = get_sb_mode();
66		initialized = true;
67	}
68
69	if (sb_mode == efi_secureboot_mode_enabled)
70		return true;
71	else
72		return false;
73}
74
75/* secureboot arch rules */
76static const char * const sb_arch_rules[] = {
77#if !IS_ENABLED(CONFIG_KEXEC_SIG)
78	"appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig",
79#endif /* CONFIG_KEXEC_SIG */
80	"measure func=KEXEC_KERNEL_CHECK",
81#if !IS_ENABLED(CONFIG_MODULE_SIG)
82	"appraise func=MODULE_CHECK appraise_type=imasig",
83#endif
84	"measure func=MODULE_CHECK",
85	NULL
86};
87
88const char * const *arch_get_ima_policy(void)
89{
90	if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot()) {
91		if (IS_ENABLED(CONFIG_MODULE_SIG))
92			set_module_sig_enforced();
93		return sb_arch_rules;
94	}
95	return NULL;
96}