security/integrity/ima/ima_crypto.c

   1 /*
   2  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
   3  *
   4  * Authors:
   5  * Mimi Zohar <zohar@us.ibm.com>
   6  * Kylene Hall <kjhall@us.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation, version 2 of the License.
  11  *
  12  * File: ima_crypto.c
  13  *      Calculates md5/sha1 file hash, template hash, boot-aggreate hash
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/kernel.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/ratelimit.h>
  21 #include <linux/file.h>
  22 #include <linux/crypto.h>
  23 #include <linux/scatterlist.h>
  24 #include <linux/err.h>
  25 #include <linux/slab.h>
  26 #include <crypto/hash.h>
  27
  28 #include "ima.h"
  29
  30 /* minimum file size for ahash use */
  31 static unsigned long ima_ahash_minsize;
  32 module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
  33 MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");
  34
  35 /* default is 0 - 1 page. */
  36 static int ima_maxorder;
  37 static unsigned int ima_bufsize = PAGE_SIZE;
  38
  39 static int param_set_bufsize(const char *val, const struct kernel_param *kp)
  40 {
  41         unsigned long long size;
  42         int order;
  43
  44         size = memparse(val, NULL);
  45         order = get_order(size);
  46         if (order >= MAX_ORDER)
  47                 return -EINVAL;
  48         ima_maxorder = order;
  49         ima_bufsize = PAGE_SIZE << order;
  50         return 0;
  51 }
  52
  53 static const struct kernel_param_ops param_ops_bufsize = {
  54         .set = param_set_bufsize,
  55         .get = param_get_uint,
  56 };
  57 #define param_check_bufsize(name, p) __param_check(name, p, unsigned int)
  58
  59 module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
  60 MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
  61
  62 static struct crypto_shash *ima_shash_tfm;
  63 static struct crypto_ahash *ima_ahash_tfm;
  64
  65 int __init ima_init_crypto(void)
  66 {
  67         long rc;
  68
  69         ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
  70         if (IS_ERR(ima_shash_tfm)) {
  71                 rc = PTR_ERR(ima_shash_tfm);
  72                 pr_err("Can not allocate %s (reason: %ld)\n",
  73                        hash_algo_name[ima_hash_algo], rc);
  74                 return rc;
  75         }
  76         pr_info("Allocated hash algorithm: %s\n",
  77                 hash_algo_name[ima_hash_algo]);
  78         return 0;
  79 }
  80
  81 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
  82 {
  83         struct crypto_shash *tfm = ima_shash_tfm;
  84         int rc;
  85
  86         if (algo < 0 || algo >= HASH_ALGO__LAST)
  87                 algo = ima_hash_algo;
  88
  89         if (algo != ima_hash_algo) {
  90                 tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
  91                 if (IS_ERR(tfm)) {
  92                         rc = PTR_ERR(tfm);
  93                         pr_err("Can not allocate %s (reason: %d)\n",
  94                                hash_algo_name[algo], rc);
  95                 }
  96         }
  97         return tfm;
  98 }
  99
 100 static void ima_free_tfm(struct crypto_shash *tfm)
 101 {
 102         if (tfm != ima_shash_tfm)
 103                 crypto_free_shash(tfm);
 104 }
 105
 106 /**
 107  * ima_alloc_pages() - Allocate contiguous pages.
 108  * @max_size:       Maximum amount of memory to allocate.
 109  * @allocated_size: Returned size of actual allocation.
 110  * @last_warn:      Should the min_size allocation warn or not.
 111  *
 112  * Tries to do opportunistic allocation for memory first trying to allocate
 113  * max_size amount of memory and then splitting that until zero order is
 114  * reached. Allocation is tried without generating allocation warnings unless
 115  * last_warn is set. Last_warn set affects only last allocation of zero order.
 116  *
 117  * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
 118  *
 119  * Return pointer to allocated memory, or NULL on failure.
 120  */
 121 static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size,
 122                              int last_warn)
 123 {
 124         void *ptr;
 125         int order = ima_maxorder;
 126         gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY;
 127
 128         if (order)
 129                 order = min(get_order(max_size), order);
 130
 131         for (; order; order--) {
 132                 ptr = (void *)__get_free_pages(gfp_mask, order);
 133                 if (ptr) {
 134                         *allocated_size = PAGE_SIZE << order;
 135                         return ptr;
 136                 }
 137         }
 138
 139         /* order is zero - one page */
 140
 141         gfp_mask = GFP_KERNEL;
 142
 143         if (!last_warn)
 144                 gfp_mask |= __GFP_NOWARN;
 145
 146         ptr = (void *)__get_free_pages(gfp_mask, 0);
 147         if (ptr) {
 148                 *allocated_size = PAGE_SIZE;
 149                 return ptr;
 150         }
 151
 152         *allocated_size = 0;
 153         return NULL;
 154 }
 155
 156 /**
 157  * ima_free_pages() - Free pages allocated by ima_alloc_pages().
 158  * @ptr:  Pointer to allocated pages.
 159  * @size: Size of allocated buffer.
 160  */
 161 static void ima_free_pages(void *ptr, size_t size)
 162 {
 163         if (!ptr)
 164                 return;
 165         free_pages((unsigned long)ptr, get_order(size));
 166 }
 167
 168 static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
 169 {
 170         struct crypto_ahash *tfm = ima_ahash_tfm;
 171         int rc;
 172
 173         if (algo < 0 || algo >= HASH_ALGO__LAST)
 174                 algo = ima_hash_algo;
 175
 176         if (algo != ima_hash_algo || !tfm) {
 177                 tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
 178                 if (!IS_ERR(tfm)) {
 179                         if (algo == ima_hash_algo)
 180                                 ima_ahash_tfm = tfm;
 181                 } else {
 182                         rc = PTR_ERR(tfm);
 183                         pr_err("Can not allocate %s (reason: %d)\n",
 184                                hash_algo_name[algo], rc);
 185                 }
 186         }
 187         return tfm;
 188 }
 189
 190 static void ima_free_atfm(struct crypto_ahash *tfm)
 191 {
 192         if (tfm != ima_ahash_tfm)
 193                 crypto_free_ahash(tfm);
 194 }
 195
 196 static inline int ahash_wait(int err, struct crypto_wait *wait)
 197 {
 198
 199         err = crypto_wait_req(err, wait);
 200
 201         if (err)
 202                 pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);
 203
 204         return err;
 205 }
 206
 207 static int ima_calc_file_hash_atfm(struct file *file,
 208                                    struct ima_digest_data *hash,
 209                                    struct crypto_ahash *tfm)
 210 {
 211         loff_t i_size, offset;
 212         char *rbuf[2] = { NULL, };
 213         int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
 214         struct ahash_request *req;
 215         struct scatterlist sg[1];
 216         struct crypto_wait wait;
 217         size_t rbuf_size[2];
 218
 219         hash->length = crypto_ahash_digestsize(tfm);
 220
 221         req = ahash_request_alloc(tfm, GFP_KERNEL);
 222         if (!req)
 223                 return -ENOMEM;
 224
 225         crypto_init_wait(&wait);
 226         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 227                                    CRYPTO_TFM_REQ_MAY_SLEEP,
 228                                    crypto_req_done, &wait);
 229
 230         rc = ahash_wait(crypto_ahash_init(req), &wait);
 231         if (rc)
 232                 goto out1;
 233
 234         i_size = i_size_read(file_inode(file));
 235
 236         if (i_size == 0)
 237                 goto out2;
 238
 239         /*
 240          * Try to allocate maximum size of memory.
 241          * Fail if even a single page cannot be allocated.
 242          */
 243         rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
 244         if (!rbuf[0]) {
 245                 rc = -ENOMEM;
 246                 goto out1;
 247         }
 248
 249         /* Only allocate one buffer if that is enough. */
 250         if (i_size > rbuf_size[0]) {
 251                 /*
 252                  * Try to allocate secondary buffer. If that fails fallback to
 253                  * using single buffering. Use previous memory allocation size
 254                  * as baseline for possible allocation size.
 255                  */
 256                 rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
 257                                           &rbuf_size[1], 0);
 258         }
 259
 260         if (!(file->f_mode & FMODE_READ)) {
 261                 file->f_mode |= FMODE_READ;
 262                 read = 1;
 263         }
 264
 265         for (offset = 0; offset < i_size; offset += rbuf_len) {
 266                 if (!rbuf[1] && offset) {
 267                         /* Not using two buffers, and it is not the first
 268                          * read/request, wait for the completion of the
 269                          * previous ahash_update() request.
 270                          */
 271                         rc = ahash_wait(ahash_rc, &wait);
 272                         if (rc)
 273                                 goto out3;
 274                 }
 275                 /* read buffer */
 276                 rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
 277                 rc = integrity_kernel_read(file, offset, rbuf[active],
 278                                            rbuf_len);
 279                 if (rc != rbuf_len)
 280                         goto out3;
 281
 282                 if (rbuf[1] && offset) {
 283                         /* Using two buffers, and it is not the first
 284                          * read/request, wait for the completion of the
 285                          * previous ahash_update() request.
 286                          */
 287                         rc = ahash_wait(ahash_rc, &wait);
 288                         if (rc)
 289                                 goto out3;
 290                 }
 291
 292                 sg_init_one(&sg[0], rbuf[active], rbuf_len);
 293                 ahash_request_set_crypt(req, sg, NULL, rbuf_len);
 294
 295                 ahash_rc = crypto_ahash_update(req);
 296
 297                 if (rbuf[1])
 298                         active = !active; /* swap buffers, if we use two */
 299         }
 300         /* wait for the last update request to complete */
 301         rc = ahash_wait(ahash_rc, &wait);
 302 out3:
 303         if (read)
 304                 file->f_mode &= ~FMODE_READ;
 305         ima_free_pages(rbuf[0], rbuf_size[0]);
 306         ima_free_pages(rbuf[1], rbuf_size[1]);
 307 out2:
 308         if (!rc) {
 309                 ahash_request_set_crypt(req, NULL, hash->digest, 0);
 310                 rc = ahash_wait(crypto_ahash_final(req), &wait);
 311         }
 312 out1:
 313         ahash_request_free(req);
 314         return rc;
 315 }
 316
 317 static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
 318 {
 319         struct crypto_ahash *tfm;
 320         int rc;
 321
 322         tfm = ima_alloc_atfm(hash->algo);
 323         if (IS_ERR(tfm))
 324                 return PTR_ERR(tfm);
 325
 326         rc = ima_calc_file_hash_atfm(file, hash, tfm);
 327
 328         ima_free_atfm(tfm);
 329
 330         return rc;
 331 }
 332
 333 static int ima_calc_file_hash_tfm(struct file *file,
 334                                   struct ima_digest_data *hash,
 335                                   struct crypto_shash *tfm)
 336 {
 337         loff_t i_size, offset = 0;
 338         char *rbuf;
 339         int rc, read = 0;
 340         SHASH_DESC_ON_STACK(shash, tfm);
 341
 342         shash->tfm = tfm;
 343         shash->flags = 0;
 344
 345         hash->length = crypto_shash_digestsize(tfm);
 346
 347         rc = crypto_shash_init(shash);
 348         if (rc != 0)
 349                 return rc;
 350
 351         i_size = i_size_read(file_inode(file));
 352
 353         if (i_size == 0)
 354                 goto out;
 355
 356         rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 357         if (!rbuf)
 358                 return -ENOMEM;
 359
 360         if (!(file->f_mode & FMODE_READ)) {
 361                 file->f_mode |= FMODE_READ;
 362                 read = 1;
 363         }
 364
 365         while (offset < i_size) {
 366                 int rbuf_len;
 367
 368                 rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
 369                 if (rbuf_len < 0) {
 370                         rc = rbuf_len;
 371                         break;
 372                 }
 373                 if (rbuf_len == 0)
 374                         break;
 375                 offset += rbuf_len;
 376
 377                 rc = crypto_shash_update(shash, rbuf, rbuf_len);
 378                 if (rc)
 379                         break;
 380         }
 381         if (read)
 382                 file->f_mode &= ~FMODE_READ;
 383         kfree(rbuf);
 384 out:
 385         if (!rc)
 386                 rc = crypto_shash_final(shash, hash->digest);
 387         return rc;
 388 }
 389
 390 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash)
 391 {
 392         struct crypto_shash *tfm;
 393         int rc;
 394
 395         tfm = ima_alloc_tfm(hash->algo);
 396         if (IS_ERR(tfm))
 397                 return PTR_ERR(tfm);
 398
 399         rc = ima_calc_file_hash_tfm(file, hash, tfm);
 400
 401         ima_free_tfm(tfm);
 402
 403         return rc;
 404 }
 405
 406 /*
 407  * ima_calc_file_hash - calculate file hash
 408  *
 409  * Asynchronous hash (ahash) allows using HW acceleration for calculating
 410  * a hash. ahash performance varies for different data sizes on different
 411  * crypto accelerators. shash performance might be better for smaller files.
 412  * The 'ima.ahash_minsize' module parameter allows specifying the best
 413  * minimum file size for using ahash on the system.
 414  *
 415  * If the ima.ahash_minsize parameter is not specified, this function uses
 416  * shash for the hash calculation.  If ahash fails, it falls back to using
 417  * shash.
 418  */
 419 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 420 {
 421         loff_t i_size;
 422         int rc;
 423
 424         /*
 425          * For consistency, fail file's opened with the O_DIRECT flag on
 426          * filesystems mounted with/without DAX option.
 427          */
 428         if (file->f_flags & O_DIRECT) {
 429                 hash->length = hash_digest_size[ima_hash_algo];
 430                 hash->algo = ima_hash_algo;
 431                 return -EINVAL;
 432         }
 433
 434         i_size = i_size_read(file_inode(file));
 435
 436         if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
 437                 rc = ima_calc_file_ahash(file, hash);
 438                 if (!rc)
 439                         return 0;
 440         }
 441
 442         return ima_calc_file_shash(file, hash);
 443 }
 444
 445 /*
 446  * Calculate the hash of template data
 447  */
 448 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
 449                                          struct ima_template_desc *td,
 450                                          int num_fields,
 451                                          struct ima_digest_data *hash,
 452                                          struct crypto_shash *tfm)
 453 {
 454         SHASH_DESC_ON_STACK(shash, tfm);
 455         int rc, i;
 456
 457         shash->tfm = tfm;
 458         shash->flags = 0;
 459
 460         hash->length = crypto_shash_digestsize(tfm);
 461
 462         rc = crypto_shash_init(shash);
 463         if (rc != 0)
 464                 return rc;
 465
 466         for (i = 0; i < num_fields; i++) {
 467                 u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
 468                 u8 *data_to_hash = field_data[i].data;
 469                 u32 datalen = field_data[i].len;
 470                 u32 datalen_to_hash =
 471                     !ima_canonical_fmt ? datalen : cpu_to_le32(datalen);
 472
 473                 if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
 474                         rc = crypto_shash_update(shash,
 475                                                 (const u8 *) &datalen_to_hash,
 476                                                 sizeof(datalen_to_hash));
 477                         if (rc)
 478                                 break;
 479                 } else if (strcmp(td->fields[i]->field_id, "n") == 0) {
 480                         memcpy(buffer, data_to_hash, datalen);
 481                         data_to_hash = buffer;
 482                         datalen = IMA_EVENT_NAME_LEN_MAX + 1;
 483                 }
 484                 rc = crypto_shash_update(shash, data_to_hash, datalen);
 485                 if (rc)
 486                         break;
 487         }
 488
 489         if (!rc)
 490                 rc = crypto_shash_final(shash, hash->digest);
 491
 492         return rc;
 493 }
 494
 495 int ima_calc_field_array_hash(struct ima_field_data *field_data,
 496                               struct ima_template_desc *desc, int num_fields,
 497                               struct ima_digest_data *hash)
 498 {
 499         struct crypto_shash *tfm;
 500         int rc;
 501
 502         tfm = ima_alloc_tfm(hash->algo);
 503         if (IS_ERR(tfm))
 504                 return PTR_ERR(tfm);
 505
 506         rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
 507                                            hash, tfm);
 508
 509         ima_free_tfm(tfm);
 510
 511         return rc;
 512 }
 513
 514 static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
 515                                   struct ima_digest_data *hash,
 516                                   struct crypto_ahash *tfm)
 517 {
 518         struct ahash_request *req;
 519         struct scatterlist sg;
 520         struct crypto_wait wait;
 521         int rc, ahash_rc = 0;
 522
 523         hash->length = crypto_ahash_digestsize(tfm);
 524
 525         req = ahash_request_alloc(tfm, GFP_KERNEL);
 526         if (!req)
 527                 return -ENOMEM;
 528
 529         crypto_init_wait(&wait);
 530         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 531                                    CRYPTO_TFM_REQ_MAY_SLEEP,
 532                                    crypto_req_done, &wait);
 533
 534         rc = ahash_wait(crypto_ahash_init(req), &wait);
 535         if (rc)
 536                 goto out;
 537
 538         sg_init_one(&sg, buf, len);
 539         ahash_request_set_crypt(req, &sg, NULL, len);
 540
 541         ahash_rc = crypto_ahash_update(req);
 542
 543         /* wait for the update request to complete */
 544         rc = ahash_wait(ahash_rc, &wait);
 545         if (!rc) {
 546                 ahash_request_set_crypt(req, NULL, hash->digest, 0);
 547                 rc = ahash_wait(crypto_ahash_final(req), &wait);
 548         }
 549 out:
 550         ahash_request_free(req);
 551         return rc;
 552 }
 553
 554 static int calc_buffer_ahash(const void *buf, loff_t len,
 555                              struct ima_digest_data *hash)
 556 {
 557         struct crypto_ahash *tfm;
 558         int rc;
 559
 560         tfm = ima_alloc_atfm(hash->algo);
 561         if (IS_ERR(tfm))
 562                 return PTR_ERR(tfm);
 563
 564         rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);
 565
 566         ima_free_atfm(tfm);
 567
 568         return rc;
 569 }
 570
 571 static int calc_buffer_shash_tfm(const void *buf, loff_t size,
 572                                 struct ima_digest_data *hash,
 573                                 struct crypto_shash *tfm)
 574 {
 575         SHASH_DESC_ON_STACK(shash, tfm);
 576         unsigned int len;
 577         int rc;
 578
 579         shash->tfm = tfm;
 580         shash->flags = 0;
 581
 582         hash->length = crypto_shash_digestsize(tfm);
 583
 584         rc = crypto_shash_init(shash);
 585         if (rc != 0)
 586                 return rc;
 587
 588         while (size) {
 589                 len = size < PAGE_SIZE ? size : PAGE_SIZE;
 590                 rc = crypto_shash_update(shash, buf, len);
 591                 if (rc)
 592                         break;
 593                 buf += len;
 594                 size -= len;
 595         }
 596
 597         if (!rc)
 598                 rc = crypto_shash_final(shash, hash->digest);
 599         return rc;
 600 }
 601
 602 static int calc_buffer_shash(const void *buf, loff_t len,
 603                              struct ima_digest_data *hash)
 604 {
 605         struct crypto_shash *tfm;
 606         int rc;
 607
 608         tfm = ima_alloc_tfm(hash->algo);
 609         if (IS_ERR(tfm))
 610                 return PTR_ERR(tfm);
 611
 612         rc = calc_buffer_shash_tfm(buf, len, hash, tfm);
 613
 614         ima_free_tfm(tfm);
 615         return rc;
 616 }
 617
 618 int ima_calc_buffer_hash(const void *buf, loff_t len,
 619                          struct ima_digest_data *hash)
 620 {
 621         int rc;
 622
 623         if (ima_ahash_minsize && len >= ima_ahash_minsize) {
 624                 rc = calc_buffer_ahash(buf, len, hash);
 625                 if (!rc)
 626                         return 0;
 627         }
 628
 629         return calc_buffer_shash(buf, len, hash);
 630 }
 631
 632 static void __init ima_pcrread(int idx, u8 *pcr)
 633 {
 634         if (!ima_tpm_chip)
 635                 return;
 636
 637         if (tpm_pcr_read(ima_tpm_chip, idx, pcr) != 0)
 638                 pr_err("Error Communicating to TPM chip\n");
 639 }
 640
 641 /*
 642  * Calculate the boot aggregate hash
 643  */
 644 static int __init ima_calc_boot_aggregate_tfm(char *digest,
 645                                               struct crypto_shash *tfm)
 646 {
 647         u8 pcr_i[TPM_DIGEST_SIZE];
 648         int rc, i;
 649         SHASH_DESC_ON_STACK(shash, tfm);
 650
 651         shash->tfm = tfm;
 652         shash->flags = 0;
 653
 654         rc = crypto_shash_init(shash);
 655         if (rc != 0)
 656                 return rc;
 657
 658         /* cumulative sha1 over tpm registers 0-7 */
 659         for (i = TPM_PCR0; i < TPM_PCR8; i++) {
 660                 ima_pcrread(i, pcr_i);
 661                 /* now accumulate with current aggregate */
 662                 rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE);
 663         }
 664         if (!rc)
 665                 crypto_shash_final(shash, digest);
 666         return rc;
 667 }
 668
 669 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
 670 {
 671         struct crypto_shash *tfm;
 672         int rc;
 673
 674         tfm = ima_alloc_tfm(hash->algo);
 675         if (IS_ERR(tfm))
 676                 return PTR_ERR(tfm);
 677
 678         hash->length = crypto_shash_digestsize(tfm);
 679         rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);
 680
 681         ima_free_tfm(tfm);
 682
 683         return rc;
 684 }