security/integrity/ima/ima_crypto.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
   4  *
   5  * Authors:
   6  * Mimi Zohar <zohar@us.ibm.com>
   7  * Kylene Hall <kjhall@us.ibm.com>
   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/moduleparam.h>
  15 #include <linux/ratelimit.h>
  16 #include <linux/file.h>
  17 #include <linux/crypto.h>
  18 #include <linux/scatterlist.h>
  19 #include <linux/err.h>
  20 #include <linux/slab.h>
  21 #include <crypto/hash.h>
  22
  23 #include "ima.h"
  24
  25 /* minimum file size for ahash use */
  26 static unsigned long ima_ahash_minsize;
  27 module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
  28 MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");
  29
  30 /* default is 0 - 1 page. */
  31 static int ima_maxorder;
  32 static unsigned int ima_bufsize = PAGE_SIZE;
  33
  34 static int param_set_bufsize(const char *val, const struct kernel_param *kp)
  35 {
  36         unsigned long long size;
  37         int order;
  38
  39         size = memparse(val, NULL);
  40         order = get_order(size);
  41         if (order >= MAX_ORDER)
  42                 return -EINVAL;
  43         ima_maxorder = order;
  44         ima_bufsize = PAGE_SIZE << order;
  45         return 0;
  46 }
  47
  48 static const struct kernel_param_ops param_ops_bufsize = {
  49         .set = param_set_bufsize,
  50         .get = param_get_uint,
  51 };
  52 #define param_check_bufsize(name, p) __param_check(name, p, unsigned int)
  53
  54 module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
  55 MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
  56
  57 static struct crypto_shash *ima_shash_tfm;
  58 static struct crypto_ahash *ima_ahash_tfm;
  59
  60 int __init ima_init_crypto(void)
  61 {
  62         long rc;
  63
  64         ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
  65         if (IS_ERR(ima_shash_tfm)) {
  66                 rc = PTR_ERR(ima_shash_tfm);
  67                 pr_err("Can not allocate %s (reason: %ld)\n",
  68                        hash_algo_name[ima_hash_algo], rc);
  69                 return rc;
  70         }
  71         pr_info("Allocated hash algorithm: %s\n",
  72                 hash_algo_name[ima_hash_algo]);
  73         return 0;
  74 }
  75
  76 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
  77 {
  78         struct crypto_shash *tfm = ima_shash_tfm;
  79         int rc;
  80
  81         if (algo < 0 || algo >= HASH_ALGO__LAST)
  82                 algo = ima_hash_algo;
  83
  84         if (algo != ima_hash_algo) {
  85                 tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
  86                 if (IS_ERR(tfm)) {
  87                         rc = PTR_ERR(tfm);
  88                         pr_err("Can not allocate %s (reason: %d)\n",
  89                                hash_algo_name[algo], rc);
  90                 }
  91         }
  92         return tfm;
  93 }
  94
  95 static void ima_free_tfm(struct crypto_shash *tfm)
  96 {
  97         if (tfm != ima_shash_tfm)
  98                 crypto_free_shash(tfm);
  99 }
 100
 101 /**
 102  * ima_alloc_pages() - Allocate contiguous pages.
 103  * @max_size:       Maximum amount of memory to allocate.
 104  * @allocated_size: Returned size of actual allocation.
 105  * @last_warn:      Should the min_size allocation warn or not.
 106  *
 107  * Tries to do opportunistic allocation for memory first trying to allocate
 108  * max_size amount of memory and then splitting that until zero order is
 109  * reached. Allocation is tried without generating allocation warnings unless
 110  * last_warn is set. Last_warn set affects only last allocation of zero order.
 111  *
 112  * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
 113  *
 114  * Return pointer to allocated memory, or NULL on failure.
 115  */
 116 static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size,
 117                              int last_warn)
 118 {
 119         void *ptr;
 120         int order = ima_maxorder;
 121         gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY;
 122
 123         if (order)
 124                 order = min(get_order(max_size), order);
 125
 126         for (; order; order--) {
 127                 ptr = (void *)__get_free_pages(gfp_mask, order);
 128                 if (ptr) {
 129                         *allocated_size = PAGE_SIZE << order;
 130                         return ptr;
 131                 }
 132         }
 133
 134         /* order is zero - one page */
 135
 136         gfp_mask = GFP_KERNEL;
 137
 138         if (!last_warn)
 139                 gfp_mask |= __GFP_NOWARN;
 140
 141         ptr = (void *)__get_free_pages(gfp_mask, 0);
 142         if (ptr) {
 143                 *allocated_size = PAGE_SIZE;
 144                 return ptr;
 145         }
 146
 147         *allocated_size = 0;
 148         return NULL;
 149 }
 150
 151 /**
 152  * ima_free_pages() - Free pages allocated by ima_alloc_pages().
 153  * @ptr:  Pointer to allocated pages.
 154  * @size: Size of allocated buffer.
 155  */
 156 static void ima_free_pages(void *ptr, size_t size)
 157 {
 158         if (!ptr)
 159                 return;
 160         free_pages((unsigned long)ptr, get_order(size));
 161 }
 162
 163 static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
 164 {
 165         struct crypto_ahash *tfm = ima_ahash_tfm;
 166         int rc;
 167
 168         if (algo < 0 || algo >= HASH_ALGO__LAST)
 169                 algo = ima_hash_algo;
 170
 171         if (algo != ima_hash_algo || !tfm) {
 172                 tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
 173                 if (!IS_ERR(tfm)) {
 174                         if (algo == ima_hash_algo)
 175                                 ima_ahash_tfm = tfm;
 176                 } else {
 177                         rc = PTR_ERR(tfm);
 178                         pr_err("Can not allocate %s (reason: %d)\n",
 179                                hash_algo_name[algo], rc);
 180                 }
 181         }
 182         return tfm;
 183 }
 184
 185 static void ima_free_atfm(struct crypto_ahash *tfm)
 186 {
 187         if (tfm != ima_ahash_tfm)
 188                 crypto_free_ahash(tfm);
 189 }
 190
 191 static inline int ahash_wait(int err, struct crypto_wait *wait)
 192 {
 193
 194         err = crypto_wait_req(err, wait);
 195
 196         if (err)
 197                 pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);
 198
 199         return err;
 200 }
 201
 202 static int ima_calc_file_hash_atfm(struct file *file,
 203                                    struct ima_digest_data *hash,
 204                                    struct crypto_ahash *tfm)
 205 {
 206         loff_t i_size, offset;
 207         char *rbuf[2] = { NULL, };
 208         int rc, rbuf_len, active = 0, ahash_rc = 0;
 209         struct ahash_request *req;
 210         struct scatterlist sg[1];
 211         struct crypto_wait wait;
 212         size_t rbuf_size[2];
 213
 214         hash->length = crypto_ahash_digestsize(tfm);
 215
 216         req = ahash_request_alloc(tfm, GFP_KERNEL);
 217         if (!req)
 218                 return -ENOMEM;
 219
 220         crypto_init_wait(&wait);
 221         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 222                                    CRYPTO_TFM_REQ_MAY_SLEEP,
 223                                    crypto_req_done, &wait);
 224
 225         rc = ahash_wait(crypto_ahash_init(req), &wait);
 226         if (rc)
 227                 goto out1;
 228
 229         i_size = i_size_read(file_inode(file));
 230
 231         if (i_size == 0)
 232                 goto out2;
 233
 234         /*
 235          * Try to allocate maximum size of memory.
 236          * Fail if even a single page cannot be allocated.
 237          */
 238         rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
 239         if (!rbuf[0]) {
 240                 rc = -ENOMEM;
 241                 goto out1;
 242         }
 243
 244         /* Only allocate one buffer if that is enough. */
 245         if (i_size > rbuf_size[0]) {
 246                 /*
 247                  * Try to allocate secondary buffer. If that fails fallback to
 248                  * using single buffering. Use previous memory allocation size
 249                  * as baseline for possible allocation size.
 250                  */
 251                 rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
 252                                           &rbuf_size[1], 0);
 253         }
 254
 255         for (offset = 0; offset < i_size; offset += rbuf_len) {
 256                 if (!rbuf[1] && offset) {
 257                         /* Not using two buffers, and it is not the first
 258                          * read/request, wait for the completion of the
 259                          * previous ahash_update() request.
 260                          */
 261                         rc = ahash_wait(ahash_rc, &wait);
 262                         if (rc)
 263                                 goto out3;
 264                 }
 265                 /* read buffer */
 266                 rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
 267                 rc = integrity_kernel_read(file, offset, rbuf[active],
 268                                            rbuf_len);
 269                 if (rc != rbuf_len) {
 270                         if (rc >= 0)
 271                                 rc = -EINVAL;
 272                         /*
 273                          * Forward current rc, do not overwrite with return value
 274                          * from ahash_wait()
 275                          */
 276                         ahash_wait(ahash_rc, &wait);
 277                         goto out3;
 278                 }
 279
 280                 if (rbuf[1] && offset) {
 281                         /* Using two buffers, and it is not the first
 282                          * read/request, wait for the completion of the
 283                          * previous ahash_update() request.
 284                          */
 285                         rc = ahash_wait(ahash_rc, &wait);
 286                         if (rc)
 287                                 goto out3;
 288                 }
 289
 290                 sg_init_one(&sg[0], rbuf[active], rbuf_len);
 291                 ahash_request_set_crypt(req, sg, NULL, rbuf_len);
 292
 293                 ahash_rc = crypto_ahash_update(req);
 294
 295                 if (rbuf[1])
 296                         active = !active; /* swap buffers, if we use two */
 297         }
 298         /* wait for the last update request to complete */
 299         rc = ahash_wait(ahash_rc, &wait);
 300 out3:
 301         ima_free_pages(rbuf[0], rbuf_size[0]);
 302         ima_free_pages(rbuf[1], rbuf_size[1]);
 303 out2:
 304         if (!rc) {
 305                 ahash_request_set_crypt(req, NULL, hash->digest, 0);
 306                 rc = ahash_wait(crypto_ahash_final(req), &wait);
 307         }
 308 out1:
 309         ahash_request_free(req);
 310         return rc;
 311 }
 312
 313 static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
 314 {
 315         struct crypto_ahash *tfm;
 316         int rc;
 317
 318         tfm = ima_alloc_atfm(hash->algo);
 319         if (IS_ERR(tfm))
 320                 return PTR_ERR(tfm);
 321
 322         rc = ima_calc_file_hash_atfm(file, hash, tfm);
 323
 324         ima_free_atfm(tfm);
 325
 326         return rc;
 327 }
 328
 329 static int ima_calc_file_hash_tfm(struct file *file,
 330                                   struct ima_digest_data *hash,
 331                                   struct crypto_shash *tfm)
 332 {
 333         loff_t i_size, offset = 0;
 334         char *rbuf;
 335         int rc;
 336         SHASH_DESC_ON_STACK(shash, tfm);
 337
 338         shash->tfm = tfm;
 339
 340         hash->length = crypto_shash_digestsize(tfm);
 341
 342         rc = crypto_shash_init(shash);
 343         if (rc != 0)
 344                 return rc;
 345
 346         i_size = i_size_read(file_inode(file));
 347
 348         if (i_size == 0)
 349                 goto out;
 350
 351         rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 352         if (!rbuf)
 353                 return -ENOMEM;
 354
 355         while (offset < i_size) {
 356                 int rbuf_len;
 357
 358                 rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
 359                 if (rbuf_len < 0) {
 360                         rc = rbuf_len;
 361                         break;
 362                 }
 363                 if (rbuf_len == 0) {    /* unexpected EOF */
 364                         rc = -EINVAL;
 365                         break;
 366                 }
 367                 offset += rbuf_len;
 368
 369                 rc = crypto_shash_update(shash, rbuf, rbuf_len);
 370                 if (rc)
 371                         break;
 372         }
 373         kfree(rbuf);
 374 out:
 375         if (!rc)
 376                 rc = crypto_shash_final(shash, hash->digest);
 377         return rc;
 378 }
 379
 380 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
 381 {
 382         struct crypto_shash *tfm;
 383         int rc;
 384
 385         tfm = ima_alloc_tfm(hash->algo);
 386         if (IS_ERR(tfm))
 387                 return PTR_ERR(tfm);
 388
 389         rc = ima_calc_file_hash_tfm(file, hash, tfm);
 390
 391         ima_free_tfm(tfm);
 392
 393         return rc;
 394 }
 395
 396 /*
 397  * ima_calc_file_hash - calculate file hash
 398  *
 399  * Asynchronous hash (ahash) allows using HW acceleration for calculating
 400  * a hash. ahash performance varies for different data sizes on different
 401  * crypto accelerators. shash performance might be better for smaller files.
 402  * The 'ima.ahash_minsize' module parameter allows specifying the best
 403  * minimum file size for using ahash on the system.
 404  *
 405  * If the ima.ahash_minsize parameter is not specified, this function uses
 406  * shash for the hash calculation.  If ahash fails, it falls back to using
 407  * shash.
 408  */
 409 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 410 {
 411         loff_t i_size;
 412         int rc;
 413         struct file *f = file;
 414         bool new_file_instance = false, modified_flags = false;
 415
 416         /*
 417          * For consistency, fail file's opened with the O_DIRECT flag on
 418          * filesystems mounted with/without DAX option.
 419          */
 420         if (file->f_flags & O_DIRECT) {
 421                 hash->length = hash_digest_size[ima_hash_algo];
 422                 hash->algo = ima_hash_algo;
 423                 return -EINVAL;
 424         }
 425
 426         /* Open a new file instance in O_RDONLY if we cannot read */
 427         if (!(file->f_mode & FMODE_READ)) {
 428                 int flags = file->f_flags & ~(O_WRONLY | O_APPEND |
 429                                 O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL);
 430                 flags |= O_RDONLY;
 431                 f = dentry_open(&file->f_path, flags, file->f_cred);
 432                 if (IS_ERR(f)) {
 433                         /*
 434                          * Cannot open the file again, lets modify f_flags
 435                          * of original and continue
 436                          */
 437                         pr_info_ratelimited("Unable to reopen file for reading.\n");
 438                         f = file;
 439                         f->f_flags |= FMODE_READ;
 440                         modified_flags = true;
 441                 } else {
 442                         new_file_instance = true;
 443                 }
 444         }
 445
 446         i_size = i_size_read(file_inode(f));
 447
 448         if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
 449                 rc = ima_calc_file_ahash(f, hash);
 450                 if (!rc)
 451                         goto out;
 452         }
 453
 454         rc = ima_calc_file_shash(f, hash);
 455 out:
 456         if (new_file_instance)
 457                 fput(f);
 458         else if (modified_flags)
 459                 f->f_flags &= ~FMODE_READ;
 460         return rc;
 461 }
 462
 463 /*
 464  * Calculate the hash of template data
 465  */
 466 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
 467                                          struct ima_template_desc *td,
 468                                          int num_fields,
 469                                          struct ima_digest_data *hash,
 470                                          struct crypto_shash *tfm)
 471 {
 472         SHASH_DESC_ON_STACK(shash, tfm);
 473         int rc, i;
 474
 475         shash->tfm = tfm;
 476
 477         hash->length = crypto_shash_digestsize(tfm);
 478
 479         rc = crypto_shash_init(shash);
 480         if (rc != 0)
 481                 return rc;
 482
 483         for (i = 0; i < num_fields; i++) {
 484                 u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
 485                 u8 *data_to_hash = field_data[i].data;
 486                 u32 datalen = field_data[i].len;
 487                 u32 datalen_to_hash =
 488                     !ima_canonical_fmt ? datalen : cpu_to_le32(datalen);
 489
 490                 if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
 491                         rc = crypto_shash_update(shash,
 492                                                 (const u8 *) &datalen_to_hash,
 493                                                 sizeof(datalen_to_hash));
 494                         if (rc)
 495                                 break;
 496                 } else if (strcmp(td->fields[i]->field_id, "n") == 0) {
 497                         memcpy(buffer, data_to_hash, datalen);
 498                         data_to_hash = buffer;
 499                         datalen = IMA_EVENT_NAME_LEN_MAX + 1;
 500                 }
 501                 rc = crypto_shash_update(shash, data_to_hash, datalen);
 502                 if (rc)
 503                         break;
 504         }
 505
 506         if (!rc)
 507                 rc = crypto_shash_final(shash, hash->digest);
 508
 509         return rc;
 510 }
 511
 512 int ima_calc_field_array_hash(struct ima_field_data *field_data,
 513                               struct ima_template_desc *desc, int num_fields,
 514                               struct ima_digest_data *hash)
 515 {
 516         struct crypto_shash *tfm;
 517         int rc;
 518
 519         tfm = ima_alloc_tfm(hash->algo);
 520         if (IS_ERR(tfm))
 521                 return PTR_ERR(tfm);
 522
 523         rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
 524                                            hash, tfm);
 525
 526         ima_free_tfm(tfm);
 527
 528         return rc;
 529 }
 530
 531 static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
 532                                   struct ima_digest_data *hash,
 533                                   struct crypto_ahash *tfm)
 534 {
 535         struct ahash_request *req;
 536         struct scatterlist sg;
 537         struct crypto_wait wait;
 538         int rc, ahash_rc = 0;
 539
 540         hash->length = crypto_ahash_digestsize(tfm);
 541
 542         req = ahash_request_alloc(tfm, GFP_KERNEL);
 543         if (!req)
 544                 return -ENOMEM;
 545
 546         crypto_init_wait(&wait);
 547         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 548                                    CRYPTO_TFM_REQ_MAY_SLEEP,
 549                                    crypto_req_done, &wait);
 550
 551         rc = ahash_wait(crypto_ahash_init(req), &wait);
 552         if (rc)
 553                 goto out;
 554
 555         sg_init_one(&sg, buf, len);
 556         ahash_request_set_crypt(req, &sg, NULL, len);
 557
 558         ahash_rc = crypto_ahash_update(req);
 559
 560         /* wait for the update request to complete */
 561         rc = ahash_wait(ahash_rc, &wait);
 562         if (!rc) {
 563                 ahash_request_set_crypt(req, NULL, hash->digest, 0);
 564                 rc = ahash_wait(crypto_ahash_final(req), &wait);
 565         }
 566 out:
 567         ahash_request_free(req);
 568         return rc;
 569 }
 570
 571 static int calc_buffer_ahash(const void *buf, loff_t len,
 572                              struct ima_digest_data *hash)
 573 {
 574         struct crypto_ahash *tfm;
 575         int rc;
 576
 577         tfm = ima_alloc_atfm(hash->algo);
 578         if (IS_ERR(tfm))
 579                 return PTR_ERR(tfm);
 580
 581         rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);
 582
 583         ima_free_atfm(tfm);
 584
 585         return rc;
 586 }
 587
 588 static int calc_buffer_shash_tfm(const void *buf, loff_t size,
 589                                 struct ima_digest_data *hash,
 590                                 struct crypto_shash *tfm)
 591 {
 592         SHASH_DESC_ON_STACK(shash, tfm);
 593         unsigned int len;
 594         int rc;
 595
 596         shash->tfm = tfm;
 597
 598         hash->length = crypto_shash_digestsize(tfm);
 599
 600         rc = crypto_shash_init(shash);
 601         if (rc != 0)
 602                 return rc;
 603
 604         while (size) {
 605                 len = size < PAGE_SIZE ? size : PAGE_SIZE;
 606                 rc = crypto_shash_update(shash, buf, len);
 607                 if (rc)
 608                         break;
 609                 buf += len;
 610                 size -= len;
 611         }
 612
 613         if (!rc)
 614                 rc = crypto_shash_final(shash, hash->digest);
 615         return rc;
 616 }
 617
 618 static int calc_buffer_shash(const void *buf, loff_t len,
 619                              struct ima_digest_data *hash)
 620 {
 621         struct crypto_shash *tfm;
 622         int rc;
 623
 624         tfm = ima_alloc_tfm(hash->algo);
 625         if (IS_ERR(tfm))
 626                 return PTR_ERR(tfm);
 627
 628         rc = calc_buffer_shash_tfm(buf, len, hash, tfm);
 629
 630         ima_free_tfm(tfm);
 631         return rc;
 632 }
 633
 634 int ima_calc_buffer_hash(const void *buf, loff_t len,
 635                          struct ima_digest_data *hash)
 636 {
 637         int rc;
 638
 639         if (ima_ahash_minsize && len >= ima_ahash_minsize) {
 640                 rc = calc_buffer_ahash(buf, len, hash);
 641                 if (!rc)
 642                         return 0;
 643         }
 644
 645         return calc_buffer_shash(buf, len, hash);
 646 }
 647
 648 static void __init ima_pcrread(u32 idx, struct tpm_digest *d)
 649 {
 650         if (!ima_tpm_chip)
 651                 return;
 652
 653         if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0)
 654                 pr_err("Error Communicating to TPM chip\n");
 655 }
 656
 657 /*
 658  * Calculate the boot aggregate hash
 659  */
 660 static int __init ima_calc_boot_aggregate_tfm(char *digest,
 661                                               struct crypto_shash *tfm)
 662 {
 663         struct tpm_digest d = { .alg_id = TPM_ALG_SHA1, .digest = {0} };
 664         int rc;
 665         u32 i;
 666         SHASH_DESC_ON_STACK(shash, tfm);
 667
 668         shash->tfm = tfm;
 669
 670         rc = crypto_shash_init(shash);
 671         if (rc != 0)
 672                 return rc;
 673
 674         /* cumulative sha1 over tpm registers 0-7 */
 675         for (i = TPM_PCR0; i < TPM_PCR8; i++) {
 676                 ima_pcrread(i, &d);
 677                 /* now accumulate with current aggregate */
 678                 rc = crypto_shash_update(shash, d.digest, TPM_DIGEST_SIZE);
 679         }
 680         if (!rc)
 681                 crypto_shash_final(shash, digest);
 682         return rc;
 683 }
 684
 685 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
 686 {
 687         struct crypto_shash *tfm;
 688         int rc;
 689
 690         tfm = ima_alloc_tfm(hash->algo);
 691         if (IS_ERR(tfm))
 692                 return PTR_ERR(tfm);
 693
 694         hash->length = crypto_shash_digestsize(tfm);
 695         rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);
 696
 697         ima_free_tfm(tfm);
 698
 699         return rc;
 700 }