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/reboot.h>
20#include <linux/slab.h>
21#include "ima.h"
22
23#define AUDIT_CAUSE_LEN_MAX 32
24
25/* pre-allocated array of tpm_digest structures to extend a PCR */
26static struct tpm_digest *digests;
27
28LIST_HEAD(ima_measurements); /* list of all measurements */
29#ifdef CONFIG_IMA_KEXEC
30static unsigned long binary_runtime_size;
31#else
32static unsigned long binary_runtime_size = ULONG_MAX;
33#endif
34
35/* key: inode (before secure-hashing a file) */
36struct ima_h_table ima_htable = {
37 .len = ATOMIC_LONG_INIT(0),
38 .violations = ATOMIC_LONG_INIT(0),
39 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
40};
41
42/* mutex protects atomicity of extending measurement list
43 * and extending the TPM PCR aggregate. Since tpm_extend can take
44 * long (and the tpm driver uses a mutex), we can't use the spinlock.
45 */
46static DEFINE_MUTEX(ima_extend_list_mutex);
47
48/*
49 * Used internally by the kernel to suspend measurements.
50 * Protected by ima_extend_list_mutex.
51 */
52static bool ima_measurements_suspended;
53
54/* lookup up the digest value in the hash table, and return the entry */
55static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
56 int pcr)
57{
58 struct ima_queue_entry *qe, *ret = NULL;
59 unsigned int key;
60 int rc;
61
62 key = ima_hash_key(digest: digest_value);
63 rcu_read_lock();
64 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
65 rc = memcmp(p: qe->entry->digests[ima_hash_algo_idx].digest,
66 q: digest_value, size: hash_digest_size[ima_hash_algo]);
67 if ((rc == 0) && (qe->entry->pcr == pcr)) {
68 ret = qe;
69 break;
70 }
71 }
72 rcu_read_unlock();
73 return ret;
74}
75
76/*
77 * Calculate the memory required for serializing a single
78 * binary_runtime_measurement list entry, which contains a
79 * couple of variable length fields (e.g template name and data).
80 */
81static int get_binary_runtime_size(struct ima_template_entry *entry)
82{
83 int size = 0;
84
85 size += sizeof(u32); /* pcr */
86 size += TPM_DIGEST_SIZE;
87 size += sizeof(int); /* template name size field */
88 size += strlen(entry->template_desc->name);
89 size += sizeof(entry->template_data_len);
90 size += entry->template_data_len;
91 return size;
92}
93
94/* ima_add_template_entry helper function:
95 * - Add template entry to the measurement list and hash table, for
96 * all entries except those carried across kexec.
97 *
98 * (Called with ima_extend_list_mutex held.)
99 */
100static int ima_add_digest_entry(struct ima_template_entry *entry,
101 bool update_htable)
102{
103 struct ima_queue_entry *qe;
104 unsigned int key;
105
106 qe = kmalloc(sizeof(*qe), GFP_KERNEL);
107 if (qe == NULL) {
108 pr_err("OUT OF MEMORY ERROR creating queue entry\n");
109 return -ENOMEM;
110 }
111 qe->entry = entry;
112
113 INIT_LIST_HEAD(list: &qe->later);
114 list_add_tail_rcu(new: &qe->later, head: &ima_measurements);
115
116 atomic_long_inc(v: &ima_htable.len);
117 if (update_htable) {
118 key = ima_hash_key(digest: entry->digests[ima_hash_algo_idx].digest);
119 hlist_add_head_rcu(n: &qe->hnext, h: &ima_htable.queue[key]);
120 }
121
122 if (binary_runtime_size != ULONG_MAX) {
123 int size;
124
125 size = get_binary_runtime_size(entry);
126 binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
127 binary_runtime_size + size : ULONG_MAX;
128 }
129 return 0;
130}
131
132/*
133 * Return the amount of memory required for serializing the
134 * entire binary_runtime_measurement list, including the ima_kexec_hdr
135 * structure.
136 */
137unsigned long ima_get_binary_runtime_size(void)
138{
139 if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
140 return ULONG_MAX;
141 else
142 return binary_runtime_size + sizeof(struct ima_kexec_hdr);
143}
144
145static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
146{
147 int result = 0;
148
149 if (!ima_tpm_chip)
150 return result;
151
152 result = tpm_pcr_extend(chip: ima_tpm_chip, pcr_idx: pcr, digests: digests_arg);
153 if (result != 0)
154 pr_err("Error Communicating to TPM chip, result: %d\n", result);
155 return result;
156}
157
158/*
159 * Add template entry to the measurement list and hash table, and
160 * extend the pcr.
161 *
162 * On systems which support carrying the IMA measurement list across
163 * kexec, maintain the total memory size required for serializing the
164 * binary_runtime_measurements.
165 */
166int ima_add_template_entry(struct ima_template_entry *entry, int violation,
167 const char *op, struct inode *inode,
168 const unsigned char *filename)
169{
170 u8 *digest = entry->digests[ima_hash_algo_idx].digest;
171 struct tpm_digest *digests_arg = entry->digests;
172 const char *audit_cause = "hash_added";
173 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
174 int audit_info = 1;
175 int result = 0, tpmresult = 0;
176
177 mutex_lock(&ima_extend_list_mutex);
178
179 /*
180 * Avoid appending to the measurement log when the TPM subsystem has
181 * been shut down while preparing for system reboot.
182 */
183 if (ima_measurements_suspended) {
184 audit_cause = "measurements_suspended";
185 audit_info = 0;
186 result = -ENODEV;
187 goto out;
188 }
189
190 if (!violation && !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
191 if (ima_lookup_digest_entry(digest_value: digest, pcr: entry->pcr)) {
192 audit_cause = "hash_exists";
193 result = -EEXIST;
194 goto out;
195 }
196 }
197
198 result = ima_add_digest_entry(entry,
199 update_htable: !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE));
200 if (result < 0) {
201 audit_cause = "ENOMEM";
202 audit_info = 0;
203 goto out;
204 }
205
206 if (violation) /* invalidate pcr */
207 digests_arg = digests;
208
209 tpmresult = ima_pcr_extend(digests_arg, pcr: entry->pcr);
210 if (tpmresult != 0) {
211 snprintf(buf: tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, fmt: "TPM_error(%d)",
212 tpmresult);
213 audit_cause = tpm_audit_cause;
214 audit_info = 0;
215 }
216out:
217 mutex_unlock(lock: &ima_extend_list_mutex);
218 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, fname: filename,
219 op, cause: audit_cause, result, info: audit_info);
220 return result;
221}
222
223int ima_restore_measurement_entry(struct ima_template_entry *entry)
224{
225 int result = 0;
226
227 mutex_lock(&ima_extend_list_mutex);
228 result = ima_add_digest_entry(entry, update_htable: 0);
229 mutex_unlock(lock: &ima_extend_list_mutex);
230 return result;
231}
232
233static void ima_measurements_suspend(void)
234{
235 mutex_lock(&ima_extend_list_mutex);
236 ima_measurements_suspended = true;
237 mutex_unlock(lock: &ima_extend_list_mutex);
238}
239
240static int ima_reboot_notifier(struct notifier_block *nb,
241 unsigned long action,
242 void *data)
243{
244#ifdef CONFIG_IMA_KEXEC
245 if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot"))
246 ima_measure_kexec_event(event_name: "kexec_execute");
247#endif
248
249 ima_measurements_suspend();
250
251 return NOTIFY_DONE;
252}
253
254static struct notifier_block ima_reboot_nb = {
255 .notifier_call = ima_reboot_notifier,
256};
257
258void __init ima_init_reboot_notifier(void)
259{
260 register_reboot_notifier(&ima_reboot_nb);
261}
262
263int __init ima_init_digests(void)
264{
265 u16 digest_size;
266 u16 crypto_id;
267 int i;
268
269 if (!ima_tpm_chip)
270 return 0;
271
272 digests = kcalloc(ima_tpm_chip->nr_allocated_banks, sizeof(*digests),
273 GFP_NOFS);
274 if (!digests)
275 return -ENOMEM;
276
277 for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
278 digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
279 digest_size = ima_tpm_chip->allocated_banks[i].digest_size;
280 crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
281
282 /* for unmapped TPM algorithms digest is still a padded SHA1 */
283 if (crypto_id == HASH_ALGO__LAST)
284 digest_size = SHA1_DIGEST_SIZE;
285
286 memset(digests[i].digest, 0xff, digest_size);
287 }
288
289 return 0;
290}
291

source code of linux/security/integrity/ima/ima_queue.c