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, 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 for (offset = 0; offset < i_size; offset += rbuf_len) { 261 if (!rbuf[1] && offset) { 262 /* Not using two buffers, and it is not the first 263 * read/request, wait for the completion of the 264 * previous ahash_update() request. 265 */ 266 rc = ahash_wait(ahash_rc, &wait); 267 if (rc) 268 goto out3; 269 } 270 /* read buffer */ 271 rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]); 272 rc = integrity_kernel_read(file, offset, rbuf[active], 273 rbuf_len); 274 if (rc != rbuf_len) 275 goto out3; 276 277 if (rbuf[1] && offset) { 278 /* Using two buffers, and it is not the first 279 * read/request, wait for the completion of the 280 * previous ahash_update() request. 281 */ 282 rc = ahash_wait(ahash_rc, &wait); 283 if (rc) 284 goto out3; 285 } 286 287 sg_init_one(&sg[0], rbuf[active], rbuf_len); 288 ahash_request_set_crypt(req, sg, NULL, rbuf_len); 289 290 ahash_rc = crypto_ahash_update(req); 291 292 if (rbuf[1]) 293 active = !active; /* swap buffers, if we use two */ 294 } 295 /* wait for the last update request to complete */ 296 rc = ahash_wait(ahash_rc, &wait); 297 out3: 298 ima_free_pages(rbuf[0], rbuf_size[0]); 299 ima_free_pages(rbuf[1], rbuf_size[1]); 300 out2: 301 if (!rc) { 302 ahash_request_set_crypt(req, NULL, hash->digest, 0); 303 rc = ahash_wait(crypto_ahash_final(req), &wait); 304 } 305 out1: 306 ahash_request_free(req); 307 return rc; 308 } 309 310 static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash) 311 { 312 struct crypto_ahash *tfm; 313 int rc; 314 315 tfm = ima_alloc_atfm(hash->algo); 316 if (IS_ERR(tfm)) 317 return PTR_ERR(tfm); 318 319 rc = ima_calc_file_hash_atfm(file, hash, tfm); 320 321 ima_free_atfm(tfm); 322 323 return rc; 324 } 325 326 static int ima_calc_file_hash_tfm(struct file *file, 327 struct ima_digest_data *hash, 328 struct crypto_shash *tfm) 329 { 330 loff_t i_size, offset = 0; 331 char *rbuf; 332 int rc; 333 SHASH_DESC_ON_STACK(shash, tfm); 334 335 shash->tfm = tfm; 336 337 hash->length = crypto_shash_digestsize(tfm); 338 339 rc = crypto_shash_init(shash); 340 if (rc != 0) 341 return rc; 342 343 i_size = i_size_read(file_inode(file)); 344 345 if (i_size == 0) 346 goto out; 347 348 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); 349 if (!rbuf) 350 return -ENOMEM; 351 352 while (offset < i_size) { 353 int rbuf_len; 354 355 rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE); 356 if (rbuf_len < 0) { 357 rc = rbuf_len; 358 break; 359 } 360 if (rbuf_len == 0) 361 break; 362 offset += rbuf_len; 363 364 rc = crypto_shash_update(shash, rbuf, rbuf_len); 365 if (rc) 366 break; 367 } 368 kfree(rbuf); 369 out: 370 if (!rc) 371 rc = crypto_shash_final(shash, hash->digest); 372 return rc; 373 } 374 375 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash) 376 { 377 struct crypto_shash *tfm; 378 int rc; 379 380 tfm = ima_alloc_tfm(hash->algo); 381 if (IS_ERR(tfm)) 382 return PTR_ERR(tfm); 383 384 rc = ima_calc_file_hash_tfm(file, hash, tfm); 385 386 ima_free_tfm(tfm); 387 388 return rc; 389 } 390 391 /* 392 * ima_calc_file_hash - calculate file hash 393 * 394 * Asynchronous hash (ahash) allows using HW acceleration for calculating 395 * a hash. ahash performance varies for different data sizes on different 396 * crypto accelerators. shash performance might be better for smaller files. 397 * The 'ima.ahash_minsize' module parameter allows specifying the best 398 * minimum file size for using ahash on the system. 399 * 400 * If the ima.ahash_minsize parameter is not specified, this function uses 401 * shash for the hash calculation. If ahash fails, it falls back to using 402 * shash. 403 */ 404 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) 405 { 406 loff_t i_size; 407 int rc; 408 struct file *f = file; 409 bool new_file_instance = false, modified_flags = false; 410 411 /* 412 * For consistency, fail file's opened with the O_DIRECT flag on 413 * filesystems mounted with/without DAX option. 414 */ 415 if (file->f_flags & O_DIRECT) { 416 hash->length = hash_digest_size[ima_hash_algo]; 417 hash->algo = ima_hash_algo; 418 return -EINVAL; 419 } 420 421 /* Open a new file instance in O_RDONLY if we cannot read */ 422 if (!(file->f_mode & FMODE_READ)) { 423 int flags = file->f_flags & ~(O_WRONLY | O_APPEND | 424 O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL); 425 flags |= O_RDONLY; 426 f = dentry_open(&file->f_path, flags, file->f_cred); 427 if (IS_ERR(f)) { 428 /* 429 * Cannot open the file again, lets modify f_flags 430 * of original and continue 431 */ 432 pr_info_ratelimited("Unable to reopen file for reading.\n"); 433 f = file; 434 f->f_flags |= FMODE_READ; 435 modified_flags = true; 436 } else { 437 new_file_instance = true; 438 } 439 } 440 441 i_size = i_size_read(file_inode(f)); 442 443 if (ima_ahash_minsize && i_size >= ima_ahash_minsize) { 444 rc = ima_calc_file_ahash(f, hash); 445 if (!rc) 446 goto out; 447 } 448 449 rc = ima_calc_file_shash(f, hash); 450 out: 451 if (new_file_instance) 452 fput(f); 453 else if (modified_flags) 454 f->f_flags &= ~FMODE_READ; 455 return rc; 456 } 457 458 /* 459 * Calculate the hash of template data 460 */ 461 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data, 462 struct ima_template_desc *td, 463 int num_fields, 464 struct ima_digest_data *hash, 465 struct crypto_shash *tfm) 466 { 467 SHASH_DESC_ON_STACK(shash, tfm); 468 int rc, i; 469 470 shash->tfm = tfm; 471 472 hash->length = crypto_shash_digestsize(tfm); 473 474 rc = crypto_shash_init(shash); 475 if (rc != 0) 476 return rc; 477 478 for (i = 0; i < num_fields; i++) { 479 u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 }; 480 u8 *data_to_hash = field_data[i].data; 481 u32 datalen = field_data[i].len; 482 u32 datalen_to_hash = 483 !ima_canonical_fmt ? datalen : cpu_to_le32(datalen); 484 485 if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) { 486 rc = crypto_shash_update(shash, 487 (const u8 *) &datalen_to_hash, 488 sizeof(datalen_to_hash)); 489 if (rc) 490 break; 491 } else if (strcmp(td->fields[i]->field_id, "n") == 0) { 492 memcpy(buffer, data_to_hash, datalen); 493 data_to_hash = buffer; 494 datalen = IMA_EVENT_NAME_LEN_MAX + 1; 495 } 496 rc = crypto_shash_update(shash, data_to_hash, datalen); 497 if (rc) 498 break; 499 } 500 501 if (!rc) 502 rc = crypto_shash_final(shash, hash->digest); 503 504 return rc; 505 } 506 507 int ima_calc_field_array_hash(struct ima_field_data *field_data, 508 struct ima_template_desc *desc, int num_fields, 509 struct ima_digest_data *hash) 510 { 511 struct crypto_shash *tfm; 512 int rc; 513 514 tfm = ima_alloc_tfm(hash->algo); 515 if (IS_ERR(tfm)) 516 return PTR_ERR(tfm); 517 518 rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields, 519 hash, tfm); 520 521 ima_free_tfm(tfm); 522 523 return rc; 524 } 525 526 static int calc_buffer_ahash_atfm(const void *buf, loff_t len, 527 struct ima_digest_data *hash, 528 struct crypto_ahash *tfm) 529 { 530 struct ahash_request *req; 531 struct scatterlist sg; 532 struct crypto_wait wait; 533 int rc, ahash_rc = 0; 534 535 hash->length = crypto_ahash_digestsize(tfm); 536 537 req = ahash_request_alloc(tfm, GFP_KERNEL); 538 if (!req) 539 return -ENOMEM; 540 541 crypto_init_wait(&wait); 542 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | 543 CRYPTO_TFM_REQ_MAY_SLEEP, 544 crypto_req_done, &wait); 545 546 rc = ahash_wait(crypto_ahash_init(req), &wait); 547 if (rc) 548 goto out; 549 550 sg_init_one(&sg, buf, len); 551 ahash_request_set_crypt(req, &sg, NULL, len); 552 553 ahash_rc = crypto_ahash_update(req); 554 555 /* wait for the update request to complete */ 556 rc = ahash_wait(ahash_rc, &wait); 557 if (!rc) { 558 ahash_request_set_crypt(req, NULL, hash->digest, 0); 559 rc = ahash_wait(crypto_ahash_final(req), &wait); 560 } 561 out: 562 ahash_request_free(req); 563 return rc; 564 } 565 566 static int calc_buffer_ahash(const void *buf, loff_t len, 567 struct ima_digest_data *hash) 568 { 569 struct crypto_ahash *tfm; 570 int rc; 571 572 tfm = ima_alloc_atfm(hash->algo); 573 if (IS_ERR(tfm)) 574 return PTR_ERR(tfm); 575 576 rc = calc_buffer_ahash_atfm(buf, len, hash, tfm); 577 578 ima_free_atfm(tfm); 579 580 return rc; 581 } 582 583 static int calc_buffer_shash_tfm(const void *buf, loff_t size, 584 struct ima_digest_data *hash, 585 struct crypto_shash *tfm) 586 { 587 SHASH_DESC_ON_STACK(shash, tfm); 588 unsigned int len; 589 int rc; 590 591 shash->tfm = tfm; 592 593 hash->length = crypto_shash_digestsize(tfm); 594 595 rc = crypto_shash_init(shash); 596 if (rc != 0) 597 return rc; 598 599 while (size) { 600 len = size < PAGE_SIZE ? size : PAGE_SIZE; 601 rc = crypto_shash_update(shash, buf, len); 602 if (rc) 603 break; 604 buf += len; 605 size -= len; 606 } 607 608 if (!rc) 609 rc = crypto_shash_final(shash, hash->digest); 610 return rc; 611 } 612 613 static int calc_buffer_shash(const void *buf, loff_t len, 614 struct ima_digest_data *hash) 615 { 616 struct crypto_shash *tfm; 617 int rc; 618 619 tfm = ima_alloc_tfm(hash->algo); 620 if (IS_ERR(tfm)) 621 return PTR_ERR(tfm); 622 623 rc = calc_buffer_shash_tfm(buf, len, hash, tfm); 624 625 ima_free_tfm(tfm); 626 return rc; 627 } 628 629 int ima_calc_buffer_hash(const void *buf, loff_t len, 630 struct ima_digest_data *hash) 631 { 632 int rc; 633 634 if (ima_ahash_minsize && len >= ima_ahash_minsize) { 635 rc = calc_buffer_ahash(buf, len, hash); 636 if (!rc) 637 return 0; 638 } 639 640 return calc_buffer_shash(buf, len, hash); 641 } 642 643 static void __init ima_pcrread(u32 idx, struct tpm_digest *d) 644 { 645 if (!ima_tpm_chip) 646 return; 647 648 if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0) 649 pr_err("Error Communicating to TPM chip\n"); 650 } 651 652 /* 653 * Calculate the boot aggregate hash 654 */ 655 static int __init ima_calc_boot_aggregate_tfm(char *digest, 656 struct crypto_shash *tfm) 657 { 658 struct tpm_digest d = { .alg_id = TPM_ALG_SHA1, .digest = {0} }; 659 int rc; 660 u32 i; 661 SHASH_DESC_ON_STACK(shash, tfm); 662 663 shash->tfm = tfm; 664 665 rc = crypto_shash_init(shash); 666 if (rc != 0) 667 return rc; 668 669 /* cumulative sha1 over tpm registers 0-7 */ 670 for (i = TPM_PCR0; i < TPM_PCR8; i++) { 671 ima_pcrread(i, &d); 672 /* now accumulate with current aggregate */ 673 rc = crypto_shash_update(shash, d.digest, TPM_DIGEST_SIZE); 674 } 675 if (!rc) 676 crypto_shash_final(shash, digest); 677 return rc; 678 } 679 680 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash) 681 { 682 struct crypto_shash *tfm; 683 int rc; 684 685 tfm = ima_alloc_tfm(hash->algo); 686 if (IS_ERR(tfm)) 687 return PTR_ERR(tfm); 688 689 hash->length = crypto_shash_digestsize(tfm); 690 rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm); 691 692 ima_free_tfm(tfm); 693 694 return rc; 695 } 696