1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
4  *
5  * Authors:
6  * Reiner Sailer      <sailer@watson.ibm.com>
7  * Leendert van Doorn <leendert@watson.ibm.com>
8  * Mimi Zohar         <zohar@us.ibm.com>
9  *
10  * File: ima_init.c
11  *             initialization and cleanup functions
12  */
13 
14 #include <linux/init.h>
15 #include <linux/scatterlist.h>
16 #include <linux/slab.h>
17 #include <linux/err.h>
18 #include <linux/ima.h>
19 #include <generated/utsrelease.h>
20 
21 #include "ima.h"
22 
23 /* name for boot aggregate entry */
24 const char boot_aggregate_name[] = "boot_aggregate";
25 struct tpm_chip *ima_tpm_chip;
26 
27 /* Add the boot aggregate to the IMA measurement list and extend
28  * the PCR register.
29  *
30  * Calculate the boot aggregate, a hash over tpm registers 0-7,
31  * assuming a TPM chip exists, and zeroes if the TPM chip does not
32  * exist.  Add the boot aggregate measurement to the measurement
33  * list and extend the PCR register.
34  *
35  * If a tpm chip does not exist, indicate the core root of trust is
36  * not hardware based by invalidating the aggregate PCR value.
37  * (The aggregate PCR value is invalidated by adding one value to
38  * the measurement list and extending the aggregate PCR value with
39  * a different value.) Violations add a zero entry to the measurement
40  * list and extend the aggregate PCR value with ff...ff's.
41  */
ima_add_boot_aggregate(void)42 static int __init ima_add_boot_aggregate(void)
43 {
44 	static const char op[] = "add_boot_aggregate";
45 	const char *audit_cause = "ENOMEM";
46 	struct ima_template_entry *entry;
47 	struct integrity_iint_cache tmp_iint, *iint = &tmp_iint;
48 	struct ima_event_data event_data = { .iint = iint,
49 					     .filename = boot_aggregate_name };
50 	struct ima_max_digest_data hash;
51 	int result = -ENOMEM;
52 	int violation = 0;
53 
54 	memset(iint, 0, sizeof(*iint));
55 	memset(&hash, 0, sizeof(hash));
56 	iint->ima_hash = &hash.hdr;
57 	iint->ima_hash->algo = ima_hash_algo;
58 	iint->ima_hash->length = hash_digest_size[ima_hash_algo];
59 
60 	/*
61 	 * With TPM 2.0 hash agility, TPM chips could support multiple TPM
62 	 * PCR banks, allowing firmware to configure and enable different
63 	 * banks.  The SHA1 bank is not necessarily enabled.
64 	 *
65 	 * Use the same hash algorithm for reading the TPM PCRs as for
66 	 * calculating the boot aggregate digest.  Preference is given to
67 	 * the configured IMA default hash algorithm.  Otherwise, use the
68 	 * TCG required banks - SHA256 for TPM 2.0, SHA1 for TPM 1.2.
69 	 * Ultimately select SHA1 also for TPM 2.0 if the SHA256 PCR bank
70 	 * is not found.
71 	 */
72 	if (ima_tpm_chip) {
73 		result = ima_calc_boot_aggregate(&hash.hdr);
74 		if (result < 0) {
75 			audit_cause = "hashing_error";
76 			goto err_out;
77 		}
78 	}
79 
80 	result = ima_alloc_init_template(&event_data, &entry, NULL);
81 	if (result < 0) {
82 		audit_cause = "alloc_entry";
83 		goto err_out;
84 	}
85 
86 	result = ima_store_template(entry, violation, NULL,
87 				    boot_aggregate_name,
88 				    CONFIG_IMA_MEASURE_PCR_IDX);
89 	if (result < 0) {
90 		ima_free_template_entry(entry);
91 		audit_cause = "store_entry";
92 		goto err_out;
93 	}
94 	return 0;
95 err_out:
96 	integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, boot_aggregate_name, op,
97 			    audit_cause, result, 0);
98 	return result;
99 }
100 
101 #ifdef CONFIG_IMA_LOAD_X509
ima_load_x509(void)102 void __init ima_load_x509(void)
103 {
104 	int unset_flags = ima_policy_flag & IMA_APPRAISE;
105 
106 	ima_policy_flag &= ~unset_flags;
107 	integrity_load_x509(INTEGRITY_KEYRING_IMA, CONFIG_IMA_X509_PATH);
108 
109 	/* load also EVM key to avoid appraisal */
110 	evm_load_x509();
111 
112 	ima_policy_flag |= unset_flags;
113 }
114 #endif
115 
ima_init(void)116 int __init ima_init(void)
117 {
118 	int rc;
119 
120 	ima_tpm_chip = tpm_default_chip();
121 	if (!ima_tpm_chip)
122 		pr_info("No TPM chip found, activating TPM-bypass!\n");
123 
124 	rc = integrity_init_keyring(INTEGRITY_KEYRING_IMA);
125 	if (rc)
126 		return rc;
127 
128 	rc = ima_init_crypto();
129 	if (rc)
130 		return rc;
131 	rc = ima_init_template();
132 	if (rc != 0)
133 		return rc;
134 
135 	/* It can be called before ima_init_digests(), it does not use TPM. */
136 	ima_load_kexec_buffer();
137 
138 	rc = ima_init_digests();
139 	if (rc != 0)
140 		return rc;
141 	rc = ima_add_boot_aggregate();	/* boot aggregate must be first entry */
142 	if (rc != 0)
143 		return rc;
144 
145 	ima_init_policy();
146 
147 	rc = ima_fs_init();
148 	if (rc != 0)
149 		return rc;
150 
151 	ima_init_key_queue();
152 
153 	ima_measure_critical_data("kernel_info", "kernel_version",
154 				  UTS_RELEASE, strlen(UTS_RELEASE), false,
155 				  NULL, 0);
156 
157 	return rc;
158 }
159