1 /* 2 * Copyright 2021 Google LLC 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 #include <assert.h> 17 #include <libcr51sign/libcr51sign.h> 18 #include <stdio.h> 19 #include <stdlib.h> 20 #include <string.h> 21 22 #ifdef __cplusplus 23 extern "C" 24 { 25 #endif 26 27 #ifndef USER_PRINT 28 #define CPRINTS(ctx, ...) fprintf(stderr, __VA_ARGS__) 29 #endif 30 31 #define MEMBER_SIZE(type, field) sizeof(((type*)0)->field) 32 33 // True of x is a power of two 34 #define POWER_OF_TWO(x) ((x) && !((x) & ((x)-1))) 35 36 // Maximum version supported. Major revisions are not backwards compatible. 37 #define MAX_MAJOR_VERSION 1 38 39 // Descriptor alignment on the external EEPROM. 40 #define DESCRIPTOR_ALIGNMENT (64 * 1024) 41 42 // SPS EEPROM sector size is 4KiB, since this is the smallest erasable size. 43 #define IMAGE_REGION_ALIGNMENT 4096 44 45 #define MAX_READ_SIZE 1024 46 47 #ifndef ARRAY_SIZE 48 #define ARRAY_SIZE(t) (sizeof(t) / sizeof(t[0])) 49 #endif 50 51 // Values of SIGNATURE_OFFSET shuold be same for all sig types (2048,3072,4096) 52 #define SIGNATURE_OFFSET offsetof(struct signature_rsa3072_pkcs15, modulus) 53 54 #ifndef BUILD_ASSERT 55 #define BUILD_ASSERT(cond) ((void)sizeof(char[1 - 2 * !(cond)])) 56 #endif 57 58 typedef enum libcr51sign_validation_failure_reason failure_reason; 59 60 // Returns the bytes size of keys used in the given signature_scheme. 61 // Return error if signature_scheme is invalid. 62 // 63 static failure_reason get_key_size(enum signature_scheme signature_scheme, 64 uint16_t* key_size) 65 { 66 switch (signature_scheme) 67 { 68 case SIGNATURE_RSA2048_PKCS15: 69 *key_size = 256; 70 return LIBCR51SIGN_SUCCESS; 71 case SIGNATURE_RSA3072_PKCS15: 72 *key_size = 384; 73 return LIBCR51SIGN_SUCCESS; 74 case SIGNATURE_RSA4096_PKCS15: 75 case SIGNATURE_RSA4096_PKCS15_SHA512: 76 *key_size = 512; 77 return LIBCR51SIGN_SUCCESS; 78 default: 79 return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; 80 } 81 } 82 83 // Returns the hash_type for a given signature scheme 84 // Returns error if scheme is invalid. 85 failure_reason get_hash_type_from_signature(enum signature_scheme scheme, 86 enum hash_type* type) 87 { 88 switch (scheme) 89 { 90 case SIGNATURE_RSA2048_PKCS15: 91 case SIGNATURE_RSA3072_PKCS15: 92 case SIGNATURE_RSA4096_PKCS15: 93 *type = HASH_SHA2_256; 94 return LIBCR51SIGN_SUCCESS; 95 case SIGNATURE_RSA4096_PKCS15_SHA512: 96 *type = HASH_SHA2_512; 97 return LIBCR51SIGN_SUCCESS; 98 default: 99 return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; 100 } 101 } 102 103 // Check if the given hash_type is supported. 104 // Returns error if hash_type is not supported. 105 static failure_reason is_hash_type_supported(enum hash_type type) 106 { 107 switch (type) 108 { 109 case HASH_SHA2_256: 110 case HASH_SHA2_512: 111 return LIBCR51SIGN_SUCCESS; 112 default: 113 return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE; 114 } 115 } 116 117 // Determines digest size for a given hash_type. 118 // Returns error if hash_type is not supported. 119 static failure_reason get_hash_digest_size(enum hash_type type, 120 uint32_t* size) 121 { 122 switch (type) 123 { 124 case HASH_SHA2_256: 125 *size = LIBCR51SIGN_SHA256_DIGEST_SIZE; 126 return LIBCR51SIGN_SUCCESS; 127 case HASH_SHA2_512: 128 *size = LIBCR51SIGN_SHA512_DIGEST_SIZE; 129 return LIBCR51SIGN_SUCCESS; 130 default: 131 return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE; 132 } 133 } 134 135 // Determines hash struct size for a given hash_type. 136 // Returns error if hash_type is not supported. 137 static failure_reason get_hash_struct_size(enum hash_type type, 138 uint32_t* size) 139 { 140 switch (type) 141 { 142 case HASH_SHA2_256: 143 *size = sizeof(struct hash_sha256); 144 return LIBCR51SIGN_SUCCESS; 145 case HASH_SHA2_512: 146 *size = sizeof(struct hash_sha256); 147 return LIBCR51SIGN_SUCCESS; 148 default: 149 return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE; 150 } 151 } 152 153 // Checks that: 154 // - The signing key is trusted 155 // - The target version is not denylisted 156 // If validating a staged update, also checks that: 157 // - The target image family matches the current image family 158 // - The image type transition is legal (i.e. dev -> *|| prod -> prod) or 159 // alternatively that the hardware ID is allowlisted 160 // Assuming the caller has performed following: 161 // board_get_base_key_index(); 162 // board_get_key_array 163 // Possible return codes: 164 // LIBCR51SIGN_SUCCESS = 0, 165 // LIBCR51SIGN_ERROR_RUNTIME_FAILURE = 1, 166 // LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR = 3, 167 // LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY = 4, 168 // LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED = 5, 169 170 static failure_reason 171 validate_transition(const struct libcr51sign_ctx* ctx, 172 const struct libcr51sign_intf* intf, 173 uint32_t signature_struct_offset) 174 { 175 BUILD_ASSERT((offsetof(struct signature_rsa2048_pkcs15, modulus) == 176 SIGNATURE_OFFSET && 177 offsetof(struct signature_rsa3072_pkcs15, modulus) == 178 SIGNATURE_OFFSET && 179 offsetof(struct signature_rsa4096_pkcs15, modulus) == 180 SIGNATURE_OFFSET)); 181 182 // Read up to the modulus. 183 enum 184 { 185 read_len = SIGNATURE_OFFSET 186 }; 187 uint8_t buffer[read_len]; 188 int rv; 189 rv = intf->read(ctx, signature_struct_offset, read_len, buffer); 190 if (rv != LIBCR51SIGN_SUCCESS) 191 { 192 CPRINTS(ctx, 193 "validate_transition: failed to read signature struct"); 194 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 195 } 196 if (*(uint32_t*)buffer != SIGNATURE_MAGIC) 197 { 198 CPRINTS(ctx, "validate_transition: bad signature magic"); 199 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 200 } 201 202 if (ctx->descriptor.image_family != ctx->current_image_family && 203 ctx->descriptor.image_family != IMAGE_FAMILY_ALL && 204 ctx->current_image_family != IMAGE_FAMILY_ALL) 205 { 206 CPRINTS(ctx, "validate_transition: invalid image family"); 207 return LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY; 208 } 209 210 if (intf->is_production_mode == NULL) 211 { 212 CPRINTS(ctx, "validate_transition: missing is_production_mode"); 213 return LIBCR51SIGN_ERROR_INVALID_INTERFACE; 214 } 215 if (intf->is_production_mode() && 216 (ctx->descriptor.image_type == IMAGE_DEV)) 217 { 218 CPRINTS(ctx, "validate_transition: checking exemption allowlist"); 219 220 // If function is NULL or if the function call return false, return 221 // error 222 if (intf->prod_to_dev_downgrade_allowed == NULL || 223 !intf->prod_to_dev_downgrade_allowed()) 224 { 225 CPRINTS(ctx, "validate_transition: illegal image type"); 226 return LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED; 227 } 228 } 229 return LIBCR51SIGN_SUCCESS; 230 } 231 232 // If caller had provided read_and_hash_update call that, otherwise call 233 // read and then update. 234 235 static failure_reason 236 read_and_hash_update(const struct libcr51sign_ctx* ctx, 237 const struct libcr51sign_intf* intf, 238 uint32_t offset, uint32_t size) 239 { 240 uint8_t read_buffer[MAX_READ_SIZE]; 241 int rv; 242 int read_size; 243 244 if (intf->read_and_hash_update) 245 { 246 rv = intf->read_and_hash_update((void*)ctx, offset, size); 247 } 248 else 249 { 250 if (!intf->hash_update) 251 { 252 CPRINTS(ctx, "read_and_hash_update: missing hash_update"); 253 return LIBCR51SIGN_ERROR_INVALID_INTERFACE; 254 } 255 do 256 { 257 read_size = size < MAX_READ_SIZE ? size : MAX_READ_SIZE; 258 rv = intf->read((void*)ctx, offset, read_size, read_buffer); 259 if (rv != LIBCR51SIGN_SUCCESS) 260 { 261 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 262 } 263 rv = intf->hash_update((void*)ctx, read_buffer, read_size); 264 if (rv != LIBCR51SIGN_SUCCESS) 265 { 266 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 267 } 268 offset += read_size; 269 size -= read_size; 270 } while (size > 0); 271 } 272 return rv; 273 } 274 275 // Validates the image_region array, namely that: 276 // - The regions are aligned, contiguous & exhaustive 277 // - That the image descriptor resides in a static region 278 // 279 // If the array is consistent, proceeds to hash the static regions and 280 // validates the hash. d_offset is the absolute image descriptor offset 281 282 static failure_reason validate_payload_regions( 283 const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf, 284 uint32_t d_offset, struct libcr51sign_validated_regions* image_regions) 285 { 286 // Allocate buffer to accomodate largest supported hash-type(SHA512) 287 uint8_t magic_and_digest[MEMBER_SIZE(struct hash_sha512, hash_magic) + 288 LIBCR51SIGN_SHA512_DIGEST_SIZE]; 289 uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE]; 290 uint32_t byte_count, region_count, image_size, hash_offset, digest_size; 291 uint32_t i; 292 uint8_t d_region_num = 0; 293 int rv; 294 struct image_region const* region; 295 296 if (image_regions == NULL) 297 { 298 CPRINTS(ctx, "Missing image region input"); 299 return LIBCR51SIGN_ERROR_INVALID_REGION_INPUT; 300 } 301 302 BUILD_ASSERT((MEMBER_SIZE(struct hash_sha256, hash_magic) == 303 MEMBER_SIZE(struct hash_sha512, hash_magic))); 304 image_size = ctx->descriptor.image_size; 305 region_count = ctx->descriptor.region_count; 306 hash_offset = d_offset + sizeof(struct image_descriptor) + 307 region_count * sizeof(struct image_region); 308 // Read the image_region array. 309 310 if (region_count > ARRAY_SIZE(image_regions->image_regions)) 311 { 312 CPRINTS(ctx, "validate_payload_regions: " 313 "ctx->descriptor.region_count is greater " 314 "than LIBCR51SIGN_MAX_REGION_COUNT"); 315 return LIBCR51SIGN_ERROR_INVALID_REGION_SIZE; 316 } 317 318 rv = intf->read(ctx, d_offset + sizeof(struct image_descriptor), 319 region_count * sizeof(struct image_region), 320 (uint8_t*)&image_regions->image_regions); 321 322 image_regions->region_count = region_count; 323 324 if (rv != LIBCR51SIGN_SUCCESS) 325 { 326 CPRINTS(ctx, 327 "validate_payload_regions: failed to read region array"); 328 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 329 } 330 331 // Validate that the regions are contiguous & exhaustive. 332 for (i = 0, byte_count = 0; i < region_count; i++) 333 { 334 region = image_regions->image_regions + i; 335 336 CPRINTS(ctx, 337 "validate_payload_regions: region #%d \"%s\" (%x - %x)", i, 338 (const char*)region->region_name, region->region_offset, 339 region->region_offset + region->region_size); 340 if ((region->region_offset % IMAGE_REGION_ALIGNMENT) != 0 || 341 (region->region_size % IMAGE_REGION_ALIGNMENT) != 0) 342 { 343 CPRINTS( 344 ctx, 345 "validate_payload_regions: regions must be sector aligned"); 346 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 347 } 348 if (region->region_offset != byte_count || 349 region->region_size > image_size - byte_count) 350 { 351 CPRINTS(ctx, "validate_payload_regions: invalid region array"); 352 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 353 } 354 byte_count += region->region_size; 355 // The image descriptor must be part of a static region. 356 if (d_offset >= region->region_offset && d_offset < byte_count) 357 { 358 d_region_num = i; 359 CPRINTS( 360 ctx, 361 "validate_payload_regions: image descriptor in region %d", 362 i); 363 // The descriptor can't span regions. 364 if (ctx->descriptor.descriptor_area_size > byte_count || 365 !(region->region_attributes & IMAGE_REGION_STATIC)) 366 { 367 CPRINTS( 368 ctx, 369 "validate_payload_regions: descriptor must reside in " 370 "static region"); 371 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 372 } 373 } 374 } 375 if (byte_count != image_size) 376 { 377 CPRINTS(ctx, "validate_payload_regions: invalid image size"); 378 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 379 } 380 381 rv = get_hash_digest_size(ctx->descriptor.hash_type, &digest_size); 382 if (rv != LIBCR51SIGN_SUCCESS) 383 { 384 return rv; 385 } 386 387 rv = intf->read(ctx, hash_offset, 388 MEMBER_SIZE(struct hash_sha256, hash_magic) + 389 digest_size, 390 magic_and_digest); 391 if (rv != LIBCR51SIGN_SUCCESS) 392 { 393 CPRINTS(ctx, 394 "validate_payload_regions: failed to read hash from flash"); 395 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 396 } 397 if (*(uint32_t*)magic_and_digest != HASH_MAGIC) 398 { 399 CPRINTS(ctx, "validate_payload_regions: bad hash magic"); 400 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 401 } 402 rv = intf->hash_init(ctx, ctx->descriptor.hash_type); 403 if (rv != LIBCR51SIGN_SUCCESS) 404 { 405 CPRINTS(ctx, "validate_payload_regions: hash_init failed"); 406 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 407 } 408 for (i = 0; i < region_count; i++) 409 { 410 uint32_t hash_start, hash_size; 411 region = image_regions->image_regions + i; 412 413 if (!(region->region_attributes & IMAGE_REGION_STATIC)) 414 { 415 continue; 416 } 417 hash_start = region->region_offset; 418 hash_size = region->region_size; 419 420 // Skip the descriptor. 421 do 422 { 423 if (i == d_region_num) 424 { 425 hash_size = d_offset - hash_start; 426 } 427 428 if (!hash_size) 429 { 430 hash_start += ctx->descriptor.descriptor_area_size; 431 hash_size = (region->region_offset + region->region_size - 432 hash_start); 433 } 434 CPRINTS("validate_payload_regions: hashing %s (%x - %x)", 435 (const char*)region->region_name, hash_start, 436 hash_start + hash_size); 437 // Read the image_region array. 438 rv = read_and_hash_update(ctx, intf, hash_start, hash_size); 439 if (rv != LIBCR51SIGN_SUCCESS) 440 { 441 return rv; 442 } 443 hash_start += hash_size; 444 } while (hash_start != region->region_offset + region->region_size); 445 } 446 rv = intf->hash_final((void*)ctx, (uint8_t*)dcrypto_digest); 447 448 if (rv != LIBCR51SIGN_SUCCESS) 449 { 450 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 451 } 452 453 if (memcmp(magic_and_digest + 454 MEMBER_SIZE(struct hash_sha256, hash_magic), 455 dcrypto_digest, digest_size)) 456 { 457 CPRINTS(ctx, "validate_payload_regions: invalid hash"); 458 return LIBCR51SIGN_ERROR_INVALID_HASH; 459 } 460 // Image is valid. 461 return LIBCR51SIGN_SUCCESS; 462 } 463 464 // Create empty image_regions to pass to validate_payload_regions 465 // Support validate_payload_regions_helper to remove image_regions as a 466 // required input. 467 468 static failure_reason 469 allocate_and_validate_payload_regions(const struct libcr51sign_ctx* ctx, 470 struct libcr51sign_intf* intf, 471 uint32_t d_offset) 472 { 473 struct libcr51sign_validated_regions image_regions; 474 return validate_payload_regions(ctx, intf, d_offset, &image_regions); 475 } 476 477 // Wrapper around validate_payload_regions to allow nullptr for 478 // image_regions. Calls allocate_and_validate_payload_regions when 479 // image_regions is nullptr to create placer holder image_regions. 480 481 static failure_reason validate_payload_regions_helper( 482 const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf, 483 uint32_t d_offset, struct libcr51sign_validated_regions* image_regions) 484 { 485 if (image_regions) 486 { 487 return validate_payload_regions(ctx, intf, d_offset, image_regions); 488 } 489 490 return allocate_and_validate_payload_regions(ctx, intf, d_offset); 491 } 492 493 // Check if the given signature_scheme is supported. 494 // Returns nonzero on error, zero on success 495 496 static failure_reason 497 is_signature_scheme_supported(enum signature_scheme scheme) 498 { 499 switch (scheme) 500 { 501 case SIGNATURE_RSA2048_PKCS15: 502 case SIGNATURE_RSA3072_PKCS15: 503 case SIGNATURE_RSA4096_PKCS15: 504 case SIGNATURE_RSA4096_PKCS15_SHA512: 505 return LIBCR51SIGN_SUCCESS; 506 default: 507 return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; 508 } 509 } 510 511 // Returns size of signature struct size in |size| 512 // Returns nonzero on error, zero on success 513 514 static failure_reason 515 get_signature_struct_size(enum signature_scheme scheme, uint32_t* size) 516 { 517 switch (scheme) 518 { 519 case SIGNATURE_RSA2048_PKCS15: 520 *size = sizeof(struct signature_rsa2048_pkcs15); 521 return LIBCR51SIGN_SUCCESS; 522 case SIGNATURE_RSA3072_PKCS15: 523 *size = sizeof(struct signature_rsa3072_pkcs15); 524 return LIBCR51SIGN_SUCCESS; 525 case SIGNATURE_RSA4096_PKCS15: 526 case SIGNATURE_RSA4096_PKCS15_SHA512: 527 *size = sizeof(struct signature_rsa4096_pkcs15); 528 return LIBCR51SIGN_SUCCESS; 529 default: 530 return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; 531 } 532 } 533 534 static failure_reason 535 get_signature_field_offset(enum signature_scheme scheme, 536 uint32_t* offset) 537 { 538 switch (scheme) 539 { 540 case SIGNATURE_RSA2048_PKCS15: 541 *offset = offsetof(struct signature_rsa2048_pkcs15, signature); 542 return LIBCR51SIGN_SUCCESS; 543 case SIGNATURE_RSA3072_PKCS15: 544 *offset = offsetof(struct signature_rsa3072_pkcs15, signature); 545 return LIBCR51SIGN_SUCCESS; 546 case SIGNATURE_RSA4096_PKCS15: 547 case SIGNATURE_RSA4096_PKCS15_SHA512: 548 *offset = offsetof(struct signature_rsa4096_pkcs15, signature); 549 return LIBCR51SIGN_SUCCESS; 550 default: 551 return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; 552 } 553 } 554 555 // Validates the signature (of type scheme) read from "device" at 556 //"raw_signature_offset" with "public_key" over a SHA256/SHA512 digest of 557 // EEPROM area "data_offset:data_size". 558 559 static failure_reason validate_signature( 560 const struct libcr51sign_ctx* ctx, const struct libcr51sign_intf* intf, 561 uint32_t data_offset, uint32_t data_size, enum signature_scheme scheme, 562 uint32_t raw_signature_offset) 563 { 564 uint8_t signature[LIBCR51SIGN_MAX_SIGNATURE_SIZE]; 565 uint16_t key_size; 566 uint32_t digest_size; 567 uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE]; 568 int rv; 569 enum hash_type hash_type; 570 571 if (!intf->hash_init) 572 { 573 CPRINTS(ctx, "validate_signature: missing hash_init"); 574 return LIBCR51SIGN_ERROR_INVALID_INTERFACE; 575 } 576 rv = get_hash_type_from_signature(scheme, &hash_type); 577 if (rv != LIBCR51SIGN_SUCCESS) 578 { 579 CPRINTS( 580 ctx, 581 "validate_payload_regions: hash_type from signature failed"); 582 return rv; 583 } 584 rv = intf->hash_init(ctx, hash_type); 585 if (rv != LIBCR51SIGN_SUCCESS) 586 { 587 CPRINTS(ctx, "validate_payload_regions: hash_init failed"); 588 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 589 } 590 rv = read_and_hash_update(ctx, intf, data_offset, data_size); 591 if (rv != LIBCR51SIGN_SUCCESS) 592 { 593 CPRINTS(ctx, "validate_signature: hash_update failed"); 594 return rv; 595 } 596 if (!intf->hash_final) 597 { 598 CPRINTS(ctx, "validate_signature: missing hash_final"); 599 return LIBCR51SIGN_ERROR_INVALID_INTERFACE; 600 } 601 rv = intf->hash_final((void*)ctx, dcrypto_digest); 602 if (rv != LIBCR51SIGN_SUCCESS) 603 { 604 CPRINTS(ctx, "validate_signature: hash_final failed (status = %d)", 605 rv); 606 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 607 } 608 rv = get_key_size(scheme, &key_size); 609 if (rv != LIBCR51SIGN_SUCCESS) 610 { 611 return rv; 612 } 613 614 rv = intf->read(ctx, raw_signature_offset, key_size, signature); 615 if (rv != LIBCR51SIGN_SUCCESS) 616 { 617 CPRINTS( 618 ctx, 619 "validate_signature: failed to read signature (status = %d)", 620 rv); 621 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 622 } 623 if (!intf->verify_signature) 624 { 625 CPRINTS(ctx, "validate_signature: missing verify_signature"); 626 return LIBCR51SIGN_ERROR_INVALID_INTERFACE; 627 } 628 rv = get_hash_digest_size(hash_type, &digest_size); 629 if (rv != LIBCR51SIGN_SUCCESS) 630 { 631 return rv; 632 } 633 rv = intf->verify_signature(ctx, scheme, signature, key_size, 634 dcrypto_digest, digest_size); 635 if (rv != LIBCR51SIGN_SUCCESS) 636 { 637 CPRINTS(ctx, 638 "validate_signature: verification failed (status = %d)", 639 rv); 640 return LIBCR51SIGN_ERROR_INVALID_SIGNATURE; 641 } 642 CPRINTS(ctx, "validate_signature: verification succeeded"); 643 return LIBCR51SIGN_SUCCESS; 644 } 645 646 // Sanity checks the image descriptor & validates its signature. 647 // This function does not validate the image_region array or image hash. 648 // 649 //@param[in] ctx context which describes the image and holds opaque private 650 // data for the user of the library 651 //@param[in] intf function pointers which interface to the current system 652 // and environment 653 //@param offset Absolute image descriptor flash offset. 654 //@param relative_offset Image descriptor offset relative to image start. 655 //@param image_size Image size in bytes. 656 //@param descriptor Output pointer to an image_descriptor struct 657 658 static failure_reason validate_descriptor( 659 const struct libcr51sign_ctx* ctx, const struct libcr51sign_intf* intf, 660 uint32_t offset, uint32_t relative_offset, uint32_t image_size) 661 { 662 uint32_t max_descriptor_size, signed_size, signature_scheme, 663 signature_offset; 664 uint32_t signature_struct_offset, signature_struct_size, 665 hash_struct_size; 666 int rv; 667 668 max_descriptor_size = image_size - relative_offset; 669 if (image_size < relative_offset || 670 max_descriptor_size < sizeof(struct image_descriptor)) 671 { 672 CPRINTS(ctx, "validate_descriptor: invalid arguments"); 673 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 674 } 675 676 rv = intf->read(ctx, offset, sizeof(ctx->descriptor), 677 (uint8_t*)&ctx->descriptor); 678 if (rv != LIBCR51SIGN_SUCCESS) 679 { 680 CPRINTS(ctx, "validate_descriptor: failed to read descriptor"); 681 return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; 682 } 683 if (ctx->descriptor.descriptor_magic != DESCRIPTOR_MAGIC || 684 ctx->descriptor.descriptor_offset != relative_offset || 685 ctx->descriptor.region_count == 0 || 686 ctx->descriptor.descriptor_area_size > max_descriptor_size || 687 ctx->descriptor.image_size != image_size) 688 { 689 CPRINTS(ctx, "validate_descriptor: invalid descriptor"); 690 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 691 } 692 if (ctx->descriptor.image_type != IMAGE_DEV && 693 ctx->descriptor.image_type != IMAGE_PROD && 694 ctx->descriptor.image_type != IMAGE_BREAKOUT && 695 ctx->descriptor.image_type != IMAGE_TEST && 696 ctx->descriptor.image_type != IMAGE_UNSIGNED_INTEGRITY) 697 { 698 CPRINTS(ctx, "validate_descriptor: bad image type"); 699 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 700 } 701 // Although the image_descriptor struct supports unauthenticated 702 // images, Haven will not allow it. 703 // Haven only supports SHA256 + RSA2048/RSA3072_PKCS15 currently. 704 705 signature_scheme = ctx->descriptor.signature_scheme; 706 707 rv = is_signature_scheme_supported(signature_scheme); 708 if (rv != LIBCR51SIGN_SUCCESS) 709 { 710 return rv; 711 } 712 rv = is_hash_type_supported(ctx->descriptor.hash_type); 713 if (rv != LIBCR51SIGN_SUCCESS) 714 { 715 CPRINTS(ctx, "validate_payload_regions: invalid hash type"); 716 return rv; 717 } 718 if (ctx->descriptor.descriptor_major > MAX_MAJOR_VERSION || 719 ctx->descriptor.region_count > LIBCR51SIGN_MAX_REGION_COUNT) 720 { 721 CPRINTS(ctx, "validate_descriptor: unsupported descriptor"); 722 return LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR; 723 } 724 rv = 725 get_signature_struct_size(signature_scheme, &signature_struct_size); 726 if (rv != LIBCR51SIGN_SUCCESS) 727 { 728 return rv; 729 } 730 731 // Compute the size of the signed portion of the image descriptor. 732 signed_size = 733 sizeof(struct image_descriptor) + 734 ctx->descriptor.region_count * sizeof(struct image_region); 735 rv = get_hash_struct_size(ctx->descriptor.hash_type, &hash_struct_size); 736 if (rv != LIBCR51SIGN_SUCCESS) 737 { 738 return rv; 739 } 740 signed_size += hash_struct_size; 741 if (ctx->descriptor.denylist_size) 742 { 743 signed_size += sizeof(struct denylist); 744 signed_size += 745 ctx->descriptor.denylist_size * sizeof(struct denylist_record); 746 } 747 if (ctx->descriptor.blob_size) 748 { 749 signed_size += sizeof(struct blob); 750 // Previous additions are guaranteed not to overflow. 751 if (ctx->descriptor.blob_size > 752 ctx->descriptor.descriptor_area_size - signed_size) 753 { 754 CPRINTS(ctx, "validate_descriptor: invalid blob size (0x%x)", 755 ctx->descriptor.blob_size); 756 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 757 } 758 signed_size += ctx->descriptor.blob_size; 759 } 760 if (signature_struct_size > 761 ctx->descriptor.descriptor_area_size - signed_size) 762 { 763 CPRINTS(ctx, 764 "validate_descriptor: invalid descriptor area size " 765 "(expected = 0x%x, actual = 0x%x)", 766 ctx->descriptor.descriptor_area_size, 767 signed_size + signature_struct_size); 768 return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; 769 } 770 signature_struct_offset = signed_size; 771 // Omit the actual signature. 772 rv = get_signature_field_offset(signature_scheme, &signature_offset); 773 if (rv != LIBCR51SIGN_SUCCESS) 774 { 775 return rv; 776 } 777 signed_size += signature_offset; 778 779 // Lookup key & validate transition. 780 rv = validate_transition(ctx, intf, offset + signature_struct_offset); 781 782 if (rv != LIBCR51SIGN_SUCCESS) 783 { 784 return rv; 785 } 786 return validate_signature(ctx, intf, offset, signed_size, 787 signature_scheme, offset + signed_size); 788 } 789 790 // Scans the external EEPROM for a magic value at "alignment" boundaries. 791 // 792 //@param device Handle to the external EEPROM. 793 //@param magic 8-byte pattern to search for. 794 //@param start_offset Offset to begin searching at. 795 //@param limit Exclusive address (e.g. EEPROM size). 796 //@param alignment Alignment boundaries (POW2) to search on. 797 //@param header_offset Location to place the new header offset. 798 //@return LIBCR51SIGN_SUCCESS (or non-zero on error). 799 800 int scan_for_magic_8(const struct libcr51sign_ctx* ctx, 801 const struct libcr51sign_intf* intf, uint64_t magic, 802 uint32_t start_offset, uint32_t limit, 803 uint32_t alignment, uint32_t* header_offset) 804 { 805 uint64_t read_data; 806 uint32_t offset; 807 int rv; 808 809 if (limit <= start_offset || limit > ctx->end_offset || 810 limit < sizeof(magic) || !POWER_OF_TWO(alignment)) 811 { 812 return LIBCR51SIGN_ERROR_INVALID_ARGUMENT; 813 } 814 815 if (!intf->read) 816 { 817 CPRINTS(ctx, "scan_for_magic_8: missing intf->read"); 818 return LIBCR51SIGN_ERROR_INVALID_INTERFACE; 819 } 820 // Align start_offset to the next valid boundary. 821 start_offset = ((start_offset - 1) & ~(alignment - 1)) + alignment; 822 for (offset = start_offset; offset < limit - sizeof(magic); 823 offset += alignment) 824 { 825 rv = intf->read((void*)ctx, offset, sizeof(read_data), 826 (uint8_t*)&read_data); 827 if (rv != LIBCR51SIGN_SUCCESS) 828 { 829 return rv; 830 } 831 if (read_data == magic) 832 { 833 if (header_offset) 834 { 835 *header_offset = offset; 836 } 837 return LIBCR51SIGN_SUCCESS; 838 } 839 } 840 // Failed to locate magic. 841 return LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC; 842 } 843 844 // Check whether the signature on the image is valid. 845 // Validates the authenticity of an EEPROM image. Scans for & validates the 846 // signature on the image descriptor. If the descriptor validates, hashes 847 // the rest of the image to verify its integrity. 848 // 849 // @param[in] ctx - context which describes the image and holds opaque 850 // private 851 // data for the user of the library 852 // @param[in] intf - function pointers which interface to the current system 853 // and environment 854 // @param[out] image_regions - image_region pointer to an array for the 855 // output 856 // 857 // @return nonzero on error, zero on success 858 859 failure_reason libcr51sign_validate( 860 const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf, 861 struct libcr51sign_validated_regions* image_regions) 862 { 863 uint32_t image_limit = 0; 864 int rv, rv_first_desc = LIBCR51SIGN_SUCCESS; 865 uint32_t descriptor_offset; 866 867 if (!ctx) 868 { 869 CPRINTS(ctx, "MIssing context"); 870 return LIBCR51SIGN_ERROR_INVALID_CONTEXT; 871 } 872 else if (!intf) 873 { 874 CPRINTS(ctx, "Missing interface"); 875 return LIBCR51SIGN_ERROR_INVALID_INTERFACE; 876 } 877 878 rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC, ctx->start_offset, 879 ctx->end_offset, DESCRIPTOR_ALIGNMENT, 880 &descriptor_offset); 881 while (rv == LIBCR51SIGN_SUCCESS) 882 { 883 CPRINTS(ctx, "validate: potential image descriptor found @%x ", 884 descriptor_offset); 885 // Validation is split into 2 functions to minimize 886 // stack usage. 887 888 rv = validate_descriptor(ctx, intf, descriptor_offset, 889 descriptor_offset - ctx->start_offset, 890 ctx->end_offset - ctx->start_offset); 891 if (rv != LIBCR51SIGN_SUCCESS) 892 { 893 CPRINTS(ctx, "validate: validate_descriptor() failed ec%d ", 894 rv); 895 } 896 897 if (rv == LIBCR51SIGN_SUCCESS) 898 { 899 rv = validate_payload_regions_helper( 900 ctx, intf, descriptor_offset, image_regions); 901 if (rv == LIBCR51SIGN_SUCCESS) 902 { 903 CPRINTS(ctx, "validate: success!"); 904 return rv; 905 } 906 CPRINTS(ctx, 907 "validate: validate_payload_regions() failed ec%d ", 908 rv); 909 } 910 // Store the first desc fail reason if any 911 if (rv != LIBCR51SIGN_SUCCESS && 912 rv_first_desc == LIBCR51SIGN_SUCCESS) 913 rv_first_desc = rv; 914 915 // scan_for_magic_8() will round up to the next aligned boundary. 916 descriptor_offset++; 917 image_limit = ctx->end_offset - ctx->start_offset; 918 rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC, 919 descriptor_offset, image_limit, 920 DESCRIPTOR_ALIGNMENT, &descriptor_offset); 921 } 922 CPRINTS(ctx, "validate: failed to validate image ec%d ", rv); 923 // If desc validation failed for some reason then return that reason 924 if (rv_first_desc != LIBCR51SIGN_SUCCESS) 925 return rv_first_desc; 926 else 927 return rv; 928 } 929 930 // @func to returns the libcr51sign error code as a string 931 // @param[in] ec - Error code 932 // @return error code in string format 933 934 const char* libcr51sign_errorcode_to_string(failure_reason ec) 935 { 936 switch (ec) 937 { 938 case LIBCR51SIGN_SUCCESS: 939 return "Success"; 940 case LIBCR51SIGN_ERROR_RUNTIME_FAILURE: 941 return "Runtime Error Failure"; 942 case LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR: 943 return "Unsupported descriptor"; 944 case LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR: 945 return "Invalid descriptor"; 946 case LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY: 947 return "Invalid image family"; 948 case LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED: 949 return "Image type disallowed"; 950 case LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED: 951 return "Dev downgrade disallowed"; 952 case LIBCR51SIGN_ERROR_UNTRUSTED_KEY: 953 return "Untrusted key"; 954 case LIBCR51SIGN_ERROR_INVALID_SIGNATURE: 955 return "Invalid signature"; 956 case LIBCR51SIGN_ERROR_INVALID_HASH: 957 return "Invalid hash"; 958 case LIBCR51SIGN_ERROR_INVALID_HASH_TYPE: 959 return "Invalid hash type"; 960 case LIBCR51SIGN_ERROR_INVALID_ARGUMENT: 961 return "Invalid Argument"; 962 case LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC: 963 return "Failed to locate descriptor"; 964 case LIBCR51SIGN_ERROR_INVALID_CONTEXT: 965 return "Invalid context"; 966 case LIBCR51SIGN_ERROR_INVALID_INTERFACE: 967 return "Invalid interface"; 968 case LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME: 969 return "Invalid signature scheme"; 970 case LIBCR51SIGN_ERROR_INVALID_REGION_INPUT: 971 return "Invalid image region input"; 972 case LIBCR51SIGN_ERROR_INVALID_REGION_SIZE: 973 return "Invalid image region size"; 974 default: 975 return "Unknown error"; 976 } 977 } 978 979 #ifdef __cplusplus 980 } // extern "C" 981 #endif 982