1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Machine keyring routines.
4  *
5  * Copyright (c) 2021, Oracle and/or its affiliates.
6  */
7 
8 #include <linux/efi.h>
9 #include "../integrity.h"
10 
11 static __init int machine_keyring_init(void)
12 {
13 	int rc;
14 
15 	rc = integrity_init_keyring(INTEGRITY_KEYRING_MACHINE);
16 	if (rc)
17 		return rc;
18 
19 	pr_notice("Machine keyring initialized\n");
20 	return 0;
21 }
22 device_initcall(machine_keyring_init);
23 
24 void __init add_to_machine_keyring(const char *source, const void *data, size_t len)
25 {
26 	key_perm_t perm;
27 	int rc;
28 
29 	perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW;
30 	rc = integrity_load_cert(INTEGRITY_KEYRING_MACHINE, source, data, len, perm);
31 
32 	/*
33 	 * Some MOKList keys may not pass the machine keyring restrictions.
34 	 * If the restriction check does not pass and the platform keyring
35 	 * is configured, try to add it into that keyring instead.
36 	 */
37 	if (rc && efi_enabled(EFI_BOOT) &&
38 	    IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING))
39 		rc = integrity_load_cert(INTEGRITY_KEYRING_PLATFORM, source,
40 					 data, len, perm);
41 
42 	if (rc)
43 		pr_info("Error adding keys to machine keyring %s\n", source);
44 }
45 
46 /*
47  * Try to load the MokListTrustedRT MOK variable to see if we should trust
48  * the MOK keys within the kernel. It is not an error if this variable
49  * does not exist.  If it does not exist, MOK keys should not be trusted
50  * within the machine keyring.
51  */
52 static __init bool uefi_check_trust_mok_keys(void)
53 {
54 	struct efi_mokvar_table_entry *mokvar_entry;
55 
56 	mokvar_entry = efi_mokvar_entry_find("MokListTrustedRT");
57 
58 	if (mokvar_entry)
59 		return true;
60 
61 	return false;
62 }
63 
64 static bool __init trust_moklist(void)
65 {
66 	static bool initialized;
67 	static bool trust_mok;
68 
69 	if (!initialized) {
70 		initialized = true;
71 		trust_mok = false;
72 
73 		if (uefi_check_trust_mok_keys())
74 			trust_mok = true;
75 	}
76 
77 	return trust_mok;
78 }
79 
80 /*
81  * Provides platform specific check for trusting imputed keys before loading
82  * on .machine keyring. UEFI systems enable this trust based on a variable,
83  * and for other platforms, it is always enabled.
84  */
85 bool __init imputed_trust_enabled(void)
86 {
87 	if (efi_enabled(EFI_BOOT))
88 		return trust_moklist();
89 
90 	return true;
91 }
92