1 /*
2  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
3  *
4  * Authors:
5  * Reiner Sailer      <sailer@watson.ibm.com>
6  * Leendert van Doorn <leendert@watson.ibm.com>
7  * Mimi Zohar         <zohar@us.ibm.com>
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License as
11  * published by the Free Software Foundation, version 2 of the
12  * License.
13  *
14  * File: ima_init.c
15  *             initialization and cleanup functions
16  */
17 
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 
20 #include <linux/module.h>
21 #include <linux/scatterlist.h>
22 #include <linux/slab.h>
23 #include <linux/err.h>
24 #include <crypto/hash_info.h>
25 #include "ima.h"
26 
27 /* name for boot aggregate entry */
28 static const char *boot_aggregate_name = "boot_aggregate";
29 int ima_used_chip;
30 
31 /* Add the boot aggregate to the IMA measurement list and extend
32  * the PCR register.
33  *
34  * Calculate the boot aggregate, a SHA1 over tpm registers 0-7,
35  * assuming a TPM chip exists, and zeroes if the TPM chip does not
36  * exist.  Add the boot aggregate measurement to the measurement
37  * list and extend the PCR register.
38  *
39  * If a tpm chip does not exist, indicate the core root of trust is
40  * not hardware based by invalidating the aggregate PCR value.
41  * (The aggregate PCR value is invalidated by adding one value to
42  * the measurement list and extending the aggregate PCR value with
43  * a different value.) Violations add a zero entry to the measurement
44  * list and extend the aggregate PCR value with ff...ff's.
45  */
46 static void __init ima_add_boot_aggregate(void)
47 {
48 	static const char op[] = "add_boot_aggregate";
49 	const char *audit_cause = "ENOMEM";
50 	struct ima_template_entry *entry;
51 	struct integrity_iint_cache tmp_iint, *iint = &tmp_iint;
52 	int result = -ENOMEM;
53 	int violation = 0;
54 	struct {
55 		struct ima_digest_data hdr;
56 		char digest[TPM_DIGEST_SIZE];
57 	} hash;
58 
59 	memset(iint, 0, sizeof(*iint));
60 	memset(&hash, 0, sizeof(hash));
61 	iint->ima_hash = &hash.hdr;
62 	iint->ima_hash->algo = HASH_ALGO_SHA1;
63 	iint->ima_hash->length = SHA1_DIGEST_SIZE;
64 
65 	if (ima_used_chip) {
66 		result = ima_calc_boot_aggregate(&hash.hdr);
67 		if (result < 0) {
68 			audit_cause = "hashing_error";
69 			goto err_out;
70 		}
71 	}
72 
73 	result = ima_alloc_init_template(iint, NULL, boot_aggregate_name,
74 					 NULL, 0, &entry);
75 	if (result < 0)
76 		return;
77 
78 	result = ima_store_template(entry, violation, NULL,
79 				    boot_aggregate_name);
80 	if (result < 0)
81 		ima_free_template_entry(entry);
82 	return;
83 err_out:
84 	integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, boot_aggregate_name, op,
85 			    audit_cause, result, 0);
86 }
87 
88 int __init ima_init(void)
89 {
90 	u8 pcr_i[TPM_DIGEST_SIZE];
91 	int rc;
92 
93 	ima_used_chip = 0;
94 	rc = tpm_pcr_read(TPM_ANY_NUM, 0, pcr_i);
95 	if (rc == 0)
96 		ima_used_chip = 1;
97 
98 	if (!ima_used_chip)
99 		pr_info("No TPM chip found, activating TPM-bypass!\n");
100 
101 	rc = ima_init_crypto();
102 	if (rc)
103 		return rc;
104 	rc = ima_init_template();
105 	if (rc != 0)
106 		return rc;
107 
108 	ima_add_boot_aggregate();	/* boot aggregate must be first entry */
109 	ima_init_policy();
110 
111 	return ima_fs_init();
112 }
113