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