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 */
25 static struct tpm_digest *digests;
26 
27 LIST_HEAD(ima_measurements);	/* list of all measurements */
28 #ifdef CONFIG_IMA_KEXEC
29 static unsigned long binary_runtime_size;
30 #else
31 static unsigned long binary_runtime_size = ULONG_MAX;
32 #endif
33 
34 /* key: inode (before secure-hashing a file) */
35 struct 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  */
45 static DEFINE_MUTEX(ima_extend_list_mutex);
46 
47 /* lookup up the digest value in the hash table, and return the entry */
48 static 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  */
74 static 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  */
93 static 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  */
130 unsigned 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 
138 static 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  */
159 int 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) {
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, 1);
180 	if (result < 0) {
181 		audit_cause = "ENOMEM";
182 		audit_info = 0;
183 		goto out;
184 	}
185 
186 	if (violation)		/* invalidate pcr */
187 		digests_arg = digests;
188 
189 	tpmresult = ima_pcr_extend(digests_arg, entry->pcr);
190 	if (tpmresult != 0) {
191 		snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
192 			 tpmresult);
193 		audit_cause = tpm_audit_cause;
194 		audit_info = 0;
195 	}
196 out:
197 	mutex_unlock(&ima_extend_list_mutex);
198 	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
199 			    op, audit_cause, result, audit_info);
200 	return result;
201 }
202 
203 int ima_restore_measurement_entry(struct ima_template_entry *entry)
204 {
205 	int result = 0;
206 
207 	mutex_lock(&ima_extend_list_mutex);
208 	result = ima_add_digest_entry(entry, 0);
209 	mutex_unlock(&ima_extend_list_mutex);
210 	return result;
211 }
212 
213 int __init ima_init_digests(void)
214 {
215 	u16 digest_size;
216 	u16 crypto_id;
217 	int i;
218 
219 	if (!ima_tpm_chip)
220 		return 0;
221 
222 	digests = kcalloc(ima_tpm_chip->nr_allocated_banks, sizeof(*digests),
223 			  GFP_NOFS);
224 	if (!digests)
225 		return -ENOMEM;
226 
227 	for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
228 		digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
229 		digest_size = ima_tpm_chip->allocated_banks[i].digest_size;
230 		crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
231 
232 		/* for unmapped TPM algorithms digest is still a padded SHA1 */
233 		if (crypto_id == HASH_ALGO__LAST)
234 			digest_size = SHA1_DIGEST_SIZE;
235 
236 		memset(digests[i].digest, 0xff, digest_size);
237 	}
238 
239 	return 0;
240 }
241