1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
4 *
5 * Authors:
6 * Serge Hallyn <serue@us.ibm.com>
7 * Reiner Sailer <sailer@watson.ibm.com>
8 * Mimi Zohar <zohar@us.ibm.com>
9 *
10 * File: ima_queue.c
11 *       Implements queues that store template measurements and
12 *       maintains aggregate over the stored measurements
13 *       in the pre-configured TPM PCR (if available).
14 *       The measurement list is append-only. No entry is
15 *       ever removed or changed during the boot-cycle.
16 */
17
18#include <linux/rculist.h>
19#include <linux/slab.h>
20#include "ima.h"
21
22#define AUDIT_CAUSE_LEN_MAX 32
23
24/* pre-allocated array of tpm_digest structures to extend a PCR */
25static struct tpm_digest *digests;
26
27LIST_HEAD(ima_measurements);	/* list of all measurements */
28#ifdef CONFIG_IMA_KEXEC
29static unsigned long binary_runtime_size;
30#else
31static unsigned long binary_runtime_size = ULONG_MAX;
32#endif
33
34/* key: inode (before secure-hashing a file) */
35struct ima_h_table ima_htable = {
36	.len = ATOMIC_LONG_INIT(0),
37	.violations = ATOMIC_LONG_INIT(0),
38	.queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
39};
40
41/* mutex protects atomicity of extending measurement list
42 * and extending the TPM PCR aggregate. Since tpm_extend can take
43 * long (and the tpm driver uses a mutex), we can't use the spinlock.
44 */
45static DEFINE_MUTEX(ima_extend_list_mutex);
46
47/* lookup up the digest value in the hash table, and return the entry */
48static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
49						       int pcr)
50{
51	struct ima_queue_entry *qe, *ret = NULL;
52	unsigned int key;
53	int rc;
54
55	key = ima_hash_key(digest_value);
56	rcu_read_lock();
57	hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
58		rc = memcmp(qe->entry->digests[ima_hash_algo_idx].digest,
59			    digest_value, hash_digest_size[ima_hash_algo]);
60		if ((rc == 0) && (qe->entry->pcr == pcr)) {
61			ret = qe;
62			break;
63		}
64	}
65	rcu_read_unlock();
66	return ret;
67}
68
69/*
70 * Calculate the memory required for serializing a single
71 * binary_runtime_measurement list entry, which contains a
72 * couple of variable length fields (e.g template name and data).
73 */
74static int get_binary_runtime_size(struct ima_template_entry *entry)
75{
76	int size = 0;
77
78	size += sizeof(u32);	/* pcr */
79	size += TPM_DIGEST_SIZE;
80	size += sizeof(int);	/* template name size field */
81	size += strlen(entry->template_desc->name);
82	size += sizeof(entry->template_data_len);
83	size += entry->template_data_len;
84	return size;
85}
86
87/* ima_add_template_entry helper function:
88 * - Add template entry to the measurement list and hash table, for
89 *   all entries except those carried across kexec.
90 *
91 * (Called with ima_extend_list_mutex held.)
92 */
93static int ima_add_digest_entry(struct ima_template_entry *entry,
94				bool update_htable)
95{
96	struct ima_queue_entry *qe;
97	unsigned int key;
98
99	qe = kmalloc(sizeof(*qe), GFP_KERNEL);
100	if (qe == NULL) {
101		pr_err("OUT OF MEMORY ERROR creating queue entry\n");
102		return -ENOMEM;
103	}
104	qe->entry = entry;
105
106	INIT_LIST_HEAD(&qe->later);
107	list_add_tail_rcu(&qe->later, &ima_measurements);
108
109	atomic_long_inc(&ima_htable.len);
110	if (update_htable) {
111		key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
112		hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
113	}
114
115	if (binary_runtime_size != ULONG_MAX) {
116		int size;
117
118		size = get_binary_runtime_size(entry);
119		binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
120		     binary_runtime_size + size : ULONG_MAX;
121	}
122	return 0;
123}
124
125/*
126 * Return the amount of memory required for serializing the
127 * entire binary_runtime_measurement list, including the ima_kexec_hdr
128 * structure.
129 */
130unsigned long ima_get_binary_runtime_size(void)
131{
132	if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
133		return ULONG_MAX;
134	else
135		return binary_runtime_size + sizeof(struct ima_kexec_hdr);
136}
137
138static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
139{
140	int result = 0;
141
142	if (!ima_tpm_chip)
143		return result;
144
145	result = tpm_pcr_extend(ima_tpm_chip, pcr, digests_arg);
146	if (result != 0)
147		pr_err("Error Communicating to TPM chip, result: %d\n", result);
148	return result;
149}
150
151/*
152 * Add template entry to the measurement list and hash table, and
153 * extend the pcr.
154 *
155 * On systems which support carrying the IMA measurement list across
156 * kexec, maintain the total memory size required for serializing the
157 * binary_runtime_measurements.
158 */
159int ima_add_template_entry(struct ima_template_entry *entry, int violation,
160			   const char *op, struct inode *inode,
161			   const unsigned char *filename)
162{
163	u8 *digest = entry->digests[ima_hash_algo_idx].digest;
164	struct tpm_digest *digests_arg = entry->digests;
165	const char *audit_cause = "hash_added";
166	char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
167	int audit_info = 1;
168	int result = 0, tpmresult = 0;
169
170	mutex_lock(&ima_extend_list_mutex);
171	if (!violation && !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
172		if (ima_lookup_digest_entry(digest, entry->pcr)) {
173			audit_cause = "hash_exists";
174			result = -EEXIST;
175			goto out;
176		}
177	}
178
179	result = ima_add_digest_entry(entry,
180				      !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE));
181	if (result < 0) {
182		audit_cause = "ENOMEM";
183		audit_info = 0;
184		goto out;
185	}
186
187	if (violation)		/* invalidate pcr */
188		digests_arg = digests;
189
190	tpmresult = ima_pcr_extend(digests_arg, entry->pcr);
191	if (tpmresult != 0) {
192		snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
193			 tpmresult);
194		audit_cause = tpm_audit_cause;
195		audit_info = 0;
196	}
197out:
198	mutex_unlock(&ima_extend_list_mutex);
199	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
200			    op, audit_cause, result, audit_info);
201	return result;
202}
203
204int ima_restore_measurement_entry(struct ima_template_entry *entry)
205{
206	int result = 0;
207
208	mutex_lock(&ima_extend_list_mutex);
209	result = ima_add_digest_entry(entry, 0);
210	mutex_unlock(&ima_extend_list_mutex);
211	return result;
212}
213
214int __init ima_init_digests(void)
215{
216	u16 digest_size;
217	u16 crypto_id;
218	int i;
219
220	if (!ima_tpm_chip)
221		return 0;
222
223	digests = kcalloc(ima_tpm_chip->nr_allocated_banks, sizeof(*digests),
224			  GFP_NOFS);
225	if (!digests)
226		return -ENOMEM;
227
228	for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
229		digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
230		digest_size = ima_tpm_chip->allocated_banks[i].digest_size;
231		crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
232
233		/* for unmapped TPM algorithms digest is still a padded SHA1 */
234		if (crypto_id == HASH_ALGO__LAST)
235			digest_size = SHA1_DIGEST_SIZE;
236
237		memset(digests[i].digest, 0xff, digest_size);
238	}
239
240	return 0;
241}
242