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 } 701