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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
4 *
5 * Authors:
6 * Mimi Zohar <[email protected]>
7 * Kylene Hall <[email protected]>
8 *
9 * File: ima_crypto.c
10 * Calculates md5/sha1 file hash, template hash, boot-aggreate hash
11 */
12
13#include <linux/kernel.h>
14#include <linux/file.h>
15#include <linux/crypto.h>
16#include <linux/err.h>
17#include <linux/slab.h>
18#include <crypto/hash.h>
19
20#include "ima.h"
21
22static struct crypto_shash *ima_shash_tfm;
23
24int ima_sha1_idx __ro_after_init;
25int ima_hash_algo_idx __ro_after_init;
26/*
27 * Additional number of slots reserved, as needed, for SHA1
28 * and IMA default algo.
29 */
30int ima_extra_slots __ro_after_init;
31
32struct ima_algo_desc *ima_algo_array __ro_after_init;
33
34static int __init ima_init_ima_crypto(void)
35{
36 long rc;
37
38 ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
39 if (IS_ERR(ima_shash_tfm)) {
40 rc = PTR_ERR(ima_shash_tfm);
41 pr_err("Can not allocate %s (reason: %ld)\n",
42 hash_algo_name[ima_hash_algo], rc);
43 return rc;
44 }
45 pr_info("Allocated hash algorithm: %s\n",
46 hash_algo_name[ima_hash_algo]);
47 return 0;
48}
49
50static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
51{
52 struct crypto_shash *tfm = ima_shash_tfm;
53 int rc, i;
54
55 if (algo < 0 || algo >= HASH_ALGO__LAST)
56 algo = ima_hash_algo;
57
58 if (algo == ima_hash_algo)
59 return tfm;
60
61 for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++)
62 if (ima_algo_array[i].tfm && ima_algo_array[i].algo == algo)
63 return ima_algo_array[i].tfm;
64
65 tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
66 if (IS_ERR(tfm)) {
67 rc = PTR_ERR(tfm);
68 pr_err("Can not allocate %s (reason: %d)\n",
69 hash_algo_name[algo], rc);
70 }
71 return tfm;
72}
73
74int __init ima_init_crypto(void)
75{
76 unsigned int digest_size;
77 enum hash_algo algo;
78 long rc;
79 int i;
80
81 rc = ima_init_ima_crypto();
82 if (rc)
83 return rc;
84
85 ima_sha1_idx = -1;
86 ima_hash_algo_idx = -1;
87
88 for (i = 0; i < NR_BANKS(ima_tpm_chip); i++) {
89 algo = ima_tpm_chip->allocated_banks[i].crypto_id;
90 if (algo == HASH_ALGO_SHA1)
91 ima_sha1_idx = i;
92
93 if (algo == ima_hash_algo)
94 ima_hash_algo_idx = i;
95 }
96
97 if (ima_sha1_idx < 0) {
98 ima_sha1_idx = NR_BANKS(ima_tpm_chip) + ima_extra_slots++;
99 if (ima_hash_algo == HASH_ALGO_SHA1)
100 ima_hash_algo_idx = ima_sha1_idx;
101 }
102
103 if (ima_hash_algo_idx < 0)
104 ima_hash_algo_idx = NR_BANKS(ima_tpm_chip) + ima_extra_slots++;
105
106 ima_algo_array = kzalloc_objs(*ima_algo_array,
107 NR_BANKS(ima_tpm_chip) + ima_extra_slots);
108 if (!ima_algo_array) {
109 rc = -ENOMEM;
110 goto out;
111 }
112
113 for (i = 0; i < NR_BANKS(ima_tpm_chip); i++) {
114 algo = ima_tpm_chip->allocated_banks[i].crypto_id;
115 digest_size = ima_tpm_chip->allocated_banks[i].digest_size;
116 ima_algo_array[i].algo = algo;
117 ima_algo_array[i].digest_size = digest_size;
118
119 /* unknown TPM algorithm */
120 if (algo == HASH_ALGO__LAST)
121 continue;
122
123 if (algo == ima_hash_algo) {
124 ima_algo_array[i].tfm = ima_shash_tfm;
125 continue;
126 }
127
128 ima_algo_array[i].tfm = ima_alloc_tfm(algo);
129 if (IS_ERR(ima_algo_array[i].tfm)) {
130 if (algo == HASH_ALGO_SHA1) {
131 rc = PTR_ERR(ima_algo_array[i].tfm);
132 ima_algo_array[i].tfm = NULL;
133 goto out_array;
134 }
135
136 ima_algo_array[i].tfm = NULL;
137 }
138 }
139
140 if (ima_sha1_idx >= NR_BANKS(ima_tpm_chip)) {
141 if (ima_hash_algo == HASH_ALGO_SHA1) {
142 ima_algo_array[ima_sha1_idx].tfm = ima_shash_tfm;
143 } else {
144 ima_algo_array[ima_sha1_idx].tfm =
145 ima_alloc_tfm(HASH_ALGO_SHA1);
146 if (IS_ERR(ima_algo_array[ima_sha1_idx].tfm)) {
147 rc = PTR_ERR(ima_algo_array[ima_sha1_idx].tfm);
148 goto out_array;
149 }
150 }
151
152 ima_algo_array[ima_sha1_idx].algo = HASH_ALGO_SHA1;
153 ima_algo_array[ima_sha1_idx].digest_size = SHA1_DIGEST_SIZE;
154 }
155
156 if (ima_hash_algo_idx >= NR_BANKS(ima_tpm_chip) &&
157 ima_hash_algo_idx != ima_sha1_idx) {
158 digest_size = hash_digest_size[ima_hash_algo];
159 ima_algo_array[ima_hash_algo_idx].tfm = ima_shash_tfm;
160 ima_algo_array[ima_hash_algo_idx].algo = ima_hash_algo;
161 ima_algo_array[ima_hash_algo_idx].digest_size = digest_size;
162 }
163
164 return 0;
165out_array:
166 for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++) {
167 if (!ima_algo_array[i].tfm ||
168 ima_algo_array[i].tfm == ima_shash_tfm)
169 continue;
170
171 crypto_free_shash(ima_algo_array[i].tfm);
172 }
173 kfree(ima_algo_array);
174out:
175 crypto_free_shash(ima_shash_tfm);
176 return rc;
177}
178
179static void ima_free_tfm(struct crypto_shash *tfm)
180{
181 int i;
182
183 if (tfm == ima_shash_tfm)
184 return;
185
186 for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++)
187 if (ima_algo_array[i].tfm == tfm)
188 return;
189
190 crypto_free_shash(tfm);
191}
192
193static int ima_calc_file_hash_tfm(struct file *file,
194 struct ima_digest_data *hash,
195 struct crypto_shash *tfm)
196{
197 loff_t i_size, offset = 0;
198 char *rbuf;
199 int rc;
200 SHASH_DESC_ON_STACK(shash, tfm);
201
202 shash->tfm = tfm;
203
204 hash->length = crypto_shash_digestsize(tfm);
205
206 rc = crypto_shash_init(shash);
207 if (rc != 0)
208 return rc;
209
210 i_size = i_size_read(file_inode(file));
211
212 if (i_size == 0)
213 goto out;
214
215 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
216 if (!rbuf)
217 return -ENOMEM;
218
219 while (offset < i_size) {
220 int rbuf_len;
221
222 rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
223 if (rbuf_len < 0) {
224 rc = rbuf_len;
225 break;
226 }
227 if (rbuf_len == 0) { /* unexpected EOF */
228 rc = -EINVAL;
229 break;
230 }
231 offset += rbuf_len;
232
233 rc = crypto_shash_update(shash, rbuf, rbuf_len);
234 if (rc)
235 break;
236 }
237 kfree(rbuf);
238out:
239 if (!rc)
240 rc = crypto_shash_final(shash, hash->digest);
241 return rc;
242}
243
244/*
245 * ima_calc_file_hash - calculate file hash
246 */
247int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
248{
249 int rc;
250 struct file *f = file;
251 bool new_file_instance = false;
252 struct crypto_shash *tfm;
253
254 /*
255 * For consistency, fail file's opened with the O_DIRECT flag on
256 * filesystems mounted with/without DAX option.
257 */
258 if (file->f_flags & O_DIRECT) {
259 hash->length = hash_digest_size[ima_hash_algo];
260 hash->algo = ima_hash_algo;
261 return -EINVAL;
262 }
263
264 /* Open a new file instance in O_RDONLY if we cannot read */
265 if (!(file->f_mode & FMODE_READ)) {
266 int flags = file->f_flags & ~(O_WRONLY | O_APPEND |
267 O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL);
268 flags |= O_RDONLY;
269 f = dentry_open(&file->f_path, flags, file->f_cred);
270 if (IS_ERR(f))
271 return PTR_ERR(f);
272
273 new_file_instance = true;
274 }
275
276 tfm = ima_alloc_tfm(hash->algo);
277 if (IS_ERR(tfm)) {
278 rc = PTR_ERR(tfm);
279 } else {
280 rc = ima_calc_file_hash_tfm(f, hash, tfm);
281 ima_free_tfm(tfm);
282 }
283 if (new_file_instance)
284 fput(f);
285 return rc;
286}
287
288/*
289 * Calculate the hash of template data
290 */
291static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
292 struct ima_template_entry *entry,
293 int tfm_idx)
294{
295 SHASH_DESC_ON_STACK(shash, ima_algo_array[tfm_idx].tfm);
296 struct ima_template_desc *td = entry->template_desc;
297 int num_fields = entry->template_desc->num_fields;
298 int rc, i;
299
300 shash->tfm = ima_algo_array[tfm_idx].tfm;
301
302 rc = crypto_shash_init(shash);
303 if (rc != 0)
304 return rc;
305
306 for (i = 0; i < num_fields; i++) {
307 u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
308 u8 *data_to_hash = field_data[i].data;
309 u32 datalen = field_data[i].len;
310 u32 datalen_to_hash = !ima_canonical_fmt ?
311 datalen : (__force u32)cpu_to_le32(datalen);
312
313 if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
314 rc = crypto_shash_update(shash,
315 (const u8 *) &datalen_to_hash,
316 sizeof(datalen_to_hash));
317 if (rc)
318 break;
319 } else if (strcmp(td->fields[i]->field_id, "n") == 0) {
320 memcpy(buffer, data_to_hash, datalen);
321 data_to_hash = buffer;
322 datalen = IMA_EVENT_NAME_LEN_MAX + 1;
323 }
324 rc = crypto_shash_update(shash, data_to_hash, datalen);
325 if (rc)
326 break;
327 }
328
329 if (!rc)
330 rc = crypto_shash_final(shash, entry->digests[tfm_idx].digest);
331
332 return rc;
333}
334
335int ima_calc_field_array_hash(struct ima_field_data *field_data,
336 struct ima_template_entry *entry)
337{
338 u16 alg_id;
339 int rc, i;
340
341 rc = ima_calc_field_array_hash_tfm(field_data, entry, ima_sha1_idx);
342 if (rc)
343 return rc;
344
345 entry->digests[ima_sha1_idx].alg_id = TPM_ALG_SHA1;
346
347 for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++) {
348 if (i == ima_sha1_idx)
349 continue;
350
351 if (i < NR_BANKS(ima_tpm_chip)) {
352 alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
353 entry->digests[i].alg_id = alg_id;
354 }
355
356 /* for unmapped TPM algorithms digest is still a padded SHA1 */
357 if (!ima_algo_array[i].tfm) {
358 memcpy(entry->digests[i].digest,
359 entry->digests[ima_sha1_idx].digest,
360 TPM_DIGEST_SIZE);
361 continue;
362 }
363
364 rc = ima_calc_field_array_hash_tfm(field_data, entry, i);
365 if (rc)
366 return rc;
367 }
368 return rc;
369}
370
371static int calc_buffer_shash_tfm(const void *buf, loff_t size,
372 struct ima_digest_data *hash,
373 struct crypto_shash *tfm)
374{
375 SHASH_DESC_ON_STACK(shash, tfm);
376 unsigned int len;
377 int rc;
378
379 shash->tfm = tfm;
380
381 hash->length = crypto_shash_digestsize(tfm);
382
383 rc = crypto_shash_init(shash);
384 if (rc != 0)
385 return rc;
386
387 while (size) {
388 len = size < PAGE_SIZE ? size : PAGE_SIZE;
389 rc = crypto_shash_update(shash, buf, len);
390 if (rc)
391 break;
392 buf += len;
393 size -= len;
394 }
395
396 if (!rc)
397 rc = crypto_shash_final(shash, hash->digest);
398 return rc;
399}
400
401int ima_calc_buffer_hash(const void *buf, loff_t len,
402 struct ima_digest_data *hash)
403{
404 struct crypto_shash *tfm;
405 int rc;
406
407 tfm = ima_alloc_tfm(hash->algo);
408 if (IS_ERR(tfm))
409 return PTR_ERR(tfm);
410
411 rc = calc_buffer_shash_tfm(buf, len, hash, tfm);
412
413 ima_free_tfm(tfm);
414 return rc;
415}
416
417static void ima_pcrread(u32 idx, struct tpm_digest *d)
418{
419 if (!ima_tpm_chip)
420 return;
421
422 if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0)
423 pr_err("Error Communicating to TPM chip\n");
424}
425
426/*
427 * The boot_aggregate is a cumulative hash over TPM registers 0 - 7. With
428 * TPM 1.2 the boot_aggregate was based on reading the SHA1 PCRs, but with
429 * TPM 2.0 hash agility, TPM chips could support multiple TPM PCR banks,
430 * allowing firmware to configure and enable different banks.
431 *
432 * Knowing which TPM bank is read to calculate the boot_aggregate digest
433 * needs to be conveyed to a verifier. For this reason, use the same
434 * hash algorithm for reading the TPM PCRs as for calculating the boot
435 * aggregate digest as stored in the measurement list.
436 */
437static int ima_calc_boot_aggregate_tfm(char *digest, u16 alg_id,
438 struct crypto_shash *tfm)
439{
440 struct tpm_digest d = { .alg_id = alg_id, .digest = {0} };
441 int rc;
442 u32 i;
443 SHASH_DESC_ON_STACK(shash, tfm);
444
445 shash->tfm = tfm;
446
447 pr_devel("calculating the boot-aggregate based on TPM bank: %04x\n",
448 d.alg_id);
449
450 rc = crypto_shash_init(shash);
451 if (rc != 0)
452 return rc;
453
454 /* cumulative digest over TPM registers 0-7 */
455 for (i = TPM_PCR0; i < TPM_PCR8; i++) {
456 ima_pcrread(i, &d);
457 /* now accumulate with current aggregate */
458 rc = crypto_shash_update(shash, d.digest,
459 crypto_shash_digestsize(tfm));
460 if (rc != 0)
461 return rc;
462 }
463 /*
464 * Extend cumulative digest over TPM registers 8-9, which contain
465 * measurement for the kernel command line (reg. 8) and image (reg. 9)
466 * in a typical PCR allocation. Registers 8-9 are only included in
467 * non-SHA1 boot_aggregate digests to avoid ambiguity.
468 */
469 if (alg_id != TPM_ALG_SHA1) {
470 for (i = TPM_PCR8; i < TPM_PCR10; i++) {
471 ima_pcrread(i, &d);
472 rc = crypto_shash_update(shash, d.digest,
473 crypto_shash_digestsize(tfm));
474 }
475 }
476 if (!rc)
477 rc = crypto_shash_final(shash, digest);
478 return rc;
479}
480
481int ima_calc_boot_aggregate(struct ima_digest_data *hash)
482{
483 struct crypto_shash *tfm;
484 u16 crypto_id, alg_id;
485 int rc, i, bank_idx = -1;
486
487 for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
488 crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
489 if (crypto_id == hash->algo) {
490 bank_idx = i;
491 break;
492 }
493
494 if (crypto_id == HASH_ALGO_SHA256)
495 bank_idx = i;
496
497 if (bank_idx == -1 && crypto_id == HASH_ALGO_SHA1)
498 bank_idx = i;
499 }
500
501 if (bank_idx == -1) {
502 pr_err("No suitable TPM algorithm for boot aggregate\n");
503 return 0;
504 }
505
506 hash->algo = ima_tpm_chip->allocated_banks[bank_idx].crypto_id;
507
508 tfm = ima_alloc_tfm(hash->algo);
509 if (IS_ERR(tfm))
510 return PTR_ERR(tfm);
511
512 hash->length = crypto_shash_digestsize(tfm);
513 alg_id = ima_tpm_chip->allocated_banks[bank_idx].alg_id;
514 rc = ima_calc_boot_aggregate_tfm(hash->digest, alg_id, tfm);
515
516 ima_free_tfm(tfm);
517
518 return rc;
519}