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