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  */
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 	int result = -ENOMEM;
51 	int violation = 0;
52 	struct {
53 		struct ima_digest_data hdr;
54 		char digest[TPM_MAX_DIGEST_SIZE];
55 	} hash;
56 
57 	memset(iint, 0, sizeof(*iint));
58 	memset(&hash, 0, sizeof(hash));
59 	iint->ima_hash = &hash.hdr;
60 	iint->ima_hash->algo = ima_hash_algo;
61 	iint->ima_hash->length = hash_digest_size[ima_hash_algo];
62 
63 	/*
64 	 * With TPM 2.0 hash agility, TPM chips could support multiple TPM
65 	 * PCR banks, allowing firmware to configure and enable different
66 	 * banks.  The SHA1 bank is not necessarily enabled.
67 	 *
68 	 * Use the same hash algorithm for reading the TPM PCRs as for
69 	 * calculating the boot aggregate digest.  Preference is given to
70 	 * the configured IMA default hash algorithm.  Otherwise, use the
71 	 * TCG required banks - SHA256 for TPM 2.0, SHA1 for TPM 1.2.
72 	 * Ultimately select SHA1 also for TPM 2.0 if the SHA256 PCR bank
73 	 * is not found.
74 	 */
75 	if (ima_tpm_chip) {
76 		result = ima_calc_boot_aggregate(&hash.hdr);
77 		if (result < 0) {
78 			audit_cause = "hashing_error";
79 			goto err_out;
80 		}
81 	}
82 
83 	result = ima_alloc_init_template(&event_data, &entry, NULL);
84 	if (result < 0) {
85 		audit_cause = "alloc_entry";
86 		goto err_out;
87 	}
88 
89 	result = ima_store_template(entry, violation, NULL,
90 				    boot_aggregate_name,
91 				    CONFIG_IMA_MEASURE_PCR_IDX);
92 	if (result < 0) {
93 		ima_free_template_entry(entry);
94 		audit_cause = "store_entry";
95 		goto err_out;
96 	}
97 	return 0;
98 err_out:
99 	integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, boot_aggregate_name, op,
100 			    audit_cause, result, 0);
101 	return result;
102 }
103 
104 #ifdef CONFIG_IMA_LOAD_X509
105 void __init ima_load_x509(void)
106 {
107 	int unset_flags = ima_policy_flag & IMA_APPRAISE;
108 
109 	ima_policy_flag &= ~unset_flags;
110 	integrity_load_x509(INTEGRITY_KEYRING_IMA, CONFIG_IMA_X509_PATH);
111 	ima_policy_flag |= unset_flags;
112 }
113 #endif
114 
115 int __init ima_init(void)
116 {
117 	int rc;
118 
119 	ima_tpm_chip = tpm_default_chip();
120 	if (!ima_tpm_chip)
121 		pr_info("No TPM chip found, activating TPM-bypass!\n");
122 
123 	rc = integrity_init_keyring(INTEGRITY_KEYRING_IMA);
124 	if (rc)
125 		return rc;
126 
127 	rc = ima_init_crypto();
128 	if (rc)
129 		return rc;
130 	rc = ima_init_template();
131 	if (rc != 0)
132 		return rc;
133 
134 	/* It can be called before ima_init_digests(), it does not use TPM. */
135 	ima_load_kexec_buffer();
136 
137 	rc = ima_init_digests();
138 	if (rc != 0)
139 		return rc;
140 	rc = ima_add_boot_aggregate();	/* boot aggregate must be first entry */
141 	if (rc != 0)
142 		return rc;
143 
144 	ima_init_policy();
145 
146 	rc = ima_fs_init();
147 	if (rc != 0)
148 		return rc;
149 
150 	ima_init_key_queue();
151 
152 	ima_measure_critical_data("kernel_info", "kernel_version",
153 				  UTS_RELEASE, strlen(UTS_RELEASE), false);
154 
155 	return rc;
156 }
157