1 /* Copyright (c) 2013 The Chromium OS Authors. All rights reserved. 2 * Use of this source code is governed by a BSD-style license that can be 3 * found in the LICENSE file. 4 * 5 * Data structure definitions for verified boot, for on-disk / in-eeprom 6 * data. 7 */ 8 9 #ifndef VBOOT_REFERENCE_VBOOT_STRUCT_H_ 10 #define VBOOT_REFERENCE_VBOOT_STRUCT_H_ 11 #include <stdint.h> 12 13 /* Public key data */ 14 typedef struct VbPublicKey { 15 /* Offset of key data from start of this struct */ 16 uint64_t key_offset; 17 /* Size of key data in bytes (NOT strength of key in bits) */ 18 uint64_t key_size; 19 /* Signature algorithm used by the key */ 20 uint64_t algorithm; 21 /* Key version */ 22 uint64_t key_version; 23 } __attribute__((packed)) VbPublicKey; 24 25 #define EXPECTED_VBPUBLICKEY_SIZE 32 26 27 /* Signature data (a secure hash, possibly signed) */ 28 typedef struct VbSignature { 29 /* Offset of signature data from start of this struct */ 30 uint64_t sig_offset; 31 /* Size of signature data in bytes */ 32 uint64_t sig_size; 33 /* Size of the data block which was signed in bytes */ 34 uint64_t data_size; 35 } __attribute__((packed)) VbSignature; 36 37 #define EXPECTED_VBSIGNATURE_SIZE 24 38 39 #define KEY_BLOCK_MAGIC "CHROMEOS" 40 #define KEY_BLOCK_MAGIC_SIZE 8 41 42 #define KEY_BLOCK_HEADER_VERSION_MAJOR 2 43 #define KEY_BLOCK_HEADER_VERSION_MINOR 1 44 45 /* Flags for key_block_flags */ 46 /* The following flags set where the key is valid */ 47 #define KEY_BLOCK_FLAG_DEVELOPER_0 (0x01ULL) /* Developer switch off */ 48 #define KEY_BLOCK_FLAG_DEVELOPER_1 (0x02ULL) /* Developer switch on */ 49 #define KEY_BLOCK_FLAG_RECOVERY_0 (0x04ULL) /* Not recovery mode */ 50 #define KEY_BLOCK_FLAG_RECOVERY_1 (0x08ULL) /* Recovery mode */ 51 52 /* 53 * Key block, containing the public key used to sign some other chunk of data. 54 * 55 * This should be followed by: 56 * 1) The data_key key data, pointed to by data_key.key_offset. 57 * 2) The checksum data for (VBKeyBlockHeader + data_key data), pointed to 58 * by key_block_checksum.sig_offset. 59 * 3) The signature data for (VBKeyBlockHeader + data_key data), pointed to 60 * by key_block_signature.sig_offset. 61 */ 62 typedef struct VbKeyBlockHeader { 63 /* Magic number */ 64 uint8_t magic[KEY_BLOCK_MAGIC_SIZE]; 65 /* Version of this header format */ 66 uint32_t header_version_major; 67 /* Version of this header format */ 68 uint32_t header_version_minor; 69 /* 70 * Length of this entire key block, including keys, signatures, and 71 * padding, in bytes 72 */ 73 uint64_t key_block_size; 74 /* 75 * Signature for this key block (header + data pointed to by data_key) 76 * For use with signed data keys 77 */ 78 VbSignature key_block_signature; 79 /* 80 * SHA-512 checksum for this key block (header + data pointed to by 81 * data_key) For use with unsigned data keys 82 */ 83 VbSignature key_block_checksum; 84 /* Flags for key (KEY_BLOCK_FLAG_*) */ 85 uint64_t key_block_flags; 86 /* Key to verify the chunk of data */ 87 VbPublicKey data_key; 88 } __attribute__((packed)) VbKeyBlockHeader; 89 90 #define EXPECTED_VBKEYBLOCKHEADER_SIZE 112 91 92 /****************************************************************************/ 93 94 #define FIRMWARE_PREAMBLE_HEADER_VERSION_MAJOR 2 95 #define FIRMWARE_PREAMBLE_HEADER_VERSION_MINOR 1 96 97 /* 98 * Preamble block for rewritable firmware, version 2.0. All 2.x versions of 99 * this struct must start with the same data, to be compatible with version 2.0 100 * readers. 101 */ 102 typedef struct VbFirmwarePreambleHeader2_0 { 103 /* 104 * Size of this preamble, including keys, signatures, and padding, in 105 * bytes 106 */ 107 uint64_t preamble_size; 108 /* 109 * Signature for this preamble (header + kernel subkey + body 110 * signature) 111 */ 112 VbSignature preamble_signature; 113 /* Version of this header format (= 2) */ 114 uint32_t header_version_major; 115 /* Version of this header format (= 0) */ 116 uint32_t header_version_minor; 117 118 /* Firmware version */ 119 uint64_t firmware_version; 120 /* Key to verify kernel key block */ 121 VbPublicKey kernel_subkey; 122 /* Signature for the firmware body */ 123 VbSignature body_signature; 124 } __attribute__((packed)) VbFirmwarePreambleHeader2_0; 125 126 #define EXPECTED_VBFIRMWAREPREAMBLEHEADER2_0_SIZE 104 127 128 /* Flags for VbFirmwarePreambleHeader.flags */ 129 /* 130 * Use the normal/dev boot path from the read-only firmware, instead of 131 * verifying the body signature. 132 */ 133 #define VB_FIRMWARE_PREAMBLE_USE_RO_NORMAL 0x00000001 134 135 /* Premable block for rewritable firmware, version 2.1. 136 * 137 * The firmware preamble header should be followed by: 138 * 1) The kernel_subkey key data, pointed to by kernel_subkey.key_offset. 139 * 2) The signature data for the firmware body, pointed to by 140 * body_signature.sig_offset. 141 * 3) The signature data for (header + kernel_subkey data + body signature 142 * data), pointed to by preamble_signature.sig_offset. 143 */ 144 typedef struct VbFirmwarePreambleHeader { 145 /* 146 * Size of this preamble, including keys, signatures, and padding, in 147 * bytes 148 */ 149 uint64_t preamble_size; 150 /* 151 * Signature for this preamble (header + kernel subkey + body 152 * signature) 153 */ 154 VbSignature preamble_signature; 155 /* Version of this header format */ 156 uint32_t header_version_major; 157 /* Version of this header format */ 158 uint32_t header_version_minor; 159 160 /* Firmware version */ 161 uint64_t firmware_version; 162 /* Key to verify kernel key block */ 163 VbPublicKey kernel_subkey; 164 /* Signature for the firmware body */ 165 VbSignature body_signature; 166 167 /* 168 * Fields added in header version 2.1. You must verify the header 169 * version before reading these fields! 170 */ 171 /* 172 * Flags; see VB_FIRMWARE_PREAMBLE_*. Readers should return 0 for 173 * header version < 2.1. 174 */ 175 uint32_t flags; 176 } __attribute__((packed)) VbFirmwarePreambleHeader; 177 178 #define EXPECTED_VBFIRMWAREPREAMBLEHEADER2_1_SIZE 108 179 180 /****************************************************************************/ 181 182 #define KERNEL_PREAMBLE_HEADER_VERSION_MAJOR 2 183 #define KERNEL_PREAMBLE_HEADER_VERSION_MINOR 2 184 185 /* Preamble block for kernel, version 2.0 186 * 187 * This should be followed by: 188 * 1) The signature data for the kernel body, pointed to by 189 * body_signature.sig_offset. 190 * 2) The signature data for (VBFirmwarePreambleHeader + body signature 191 * data), pointed to by preamble_signature.sig_offset. 192 */ 193 typedef struct VbKernelPreambleHeader2_0 { 194 /* 195 * Size of this preamble, including keys, signatures, and padding, in 196 * bytes 197 */ 198 uint64_t preamble_size; 199 /* Signature for this preamble (header + body signature) */ 200 VbSignature preamble_signature; 201 /* Version of this header format */ 202 uint32_t header_version_major; 203 /* Version of this header format */ 204 uint32_t header_version_minor; 205 206 /* Kernel version */ 207 uint64_t kernel_version; 208 /* Load address for kernel body */ 209 uint64_t body_load_address; 210 /* Address of bootloader, after body is loaded at body_load_address */ 211 uint64_t bootloader_address; 212 /* Size of bootloader in bytes */ 213 uint64_t bootloader_size; 214 /* Signature for the kernel body */ 215 VbSignature body_signature; 216 } __attribute__((packed)) VbKernelPreambleHeader2_0; 217 218 #define EXPECTED_VBKERNELPREAMBLEHEADER2_0_SIZE 96 219 220 /* Preamble block for kernel, version 2.1 221 * 222 * This should be followed by: 223 * 1) The signature data for the kernel body, pointed to by 224 * body_signature.sig_offset. 225 * 2) The signature data for (VBFirmwarePreambleHeader + body signature 226 * data), pointed to by preamble_signature.sig_offset. 227 * 3) The 16-bit vmlinuz header, which is used for reconstruction of 228 * vmlinuz image. 229 */ 230 typedef struct VbKernelPreambleHeader { 231 /* 232 * Size of this preamble, including keys, signatures, vmlinuz header, 233 * and padding, in bytes 234 */ 235 uint64_t preamble_size; 236 /* Signature for this preamble (header + body signature) */ 237 VbSignature preamble_signature; 238 /* Version of this header format */ 239 uint32_t header_version_major; 240 /* Version of this header format */ 241 uint32_t header_version_minor; 242 243 /* Kernel version */ 244 uint64_t kernel_version; 245 /* Load address for kernel body */ 246 uint64_t body_load_address; 247 /* Address of bootloader, after body is loaded at body_load_address */ 248 uint64_t bootloader_address; 249 /* Size of bootloader in bytes */ 250 uint64_t bootloader_size; 251 /* Signature for the kernel body */ 252 VbSignature body_signature; 253 /* 254 * Fields added in header version 2.1. You must verify the header 255 * version before reading these fields! 256 */ 257 /* Address of 16-bit header for vmlinuz reassembly. Readers should 258 return 0 for header version < 2.1 */ 259 uint64_t vmlinuz_header_address; 260 /* Size of 16-bit header for vmlinuz in bytes. Readers should return 0 261 for header version < 2.1 */ 262 uint64_t vmlinuz_header_size; 263 /* 264 * Flags passed in by the signer. Readers should return 0 for header 265 * version < 2.2. Flags field is currently defined as: 266 * [31:2] - Reserved (for future use) 267 * [1:0] - Kernel image type (0b00 - CrOS, 0b01 - bootimg) 268 */ 269 uint32_t flags; 270 } __attribute__((packed)) VbKernelPreambleHeader; 271 272 #define EXPECTED_VBKERNELPREAMBLEHEADER2_1_SIZE 112 273 #define EXPECTED_VBKERNELPREAMBLEHEADER2_2_SIZE 116 274 275 /****************************************************************************/ 276 277 /* Constants and sub-structures for VbSharedDataHeader */ 278 279 /* Magic number for recognizing VbSharedDataHeader ("VbSD") */ 280 #define VB_SHARED_DATA_MAGIC 0x44536256 281 282 /* Minimum and recommended size of shared_data_blob in bytes. */ 283 #define VB_SHARED_DATA_MIN_SIZE 3072 284 #define VB_SHARED_DATA_REC_SIZE 16384 285 286 /* Flags for VbSharedDataHeader */ 287 /* LoadFirmware() tried firmware B because of VbNvStorage firmware B tries */ 288 #define VBSD_FWB_TRIED 0x00000001 289 /* 290 * LoadKernel() verified the good kernel keyblock using the kernel subkey from 291 * the firmware. If this flag is not present, it just used the hash of the 292 * kernel keyblock. 293 */ 294 #define VBSD_KERNEL_KEY_VERIFIED 0x00000002 295 /* LoadFirmware() was told the developer switch was on */ 296 #define VBSD_LF_DEV_SWITCH_ON 0x00000004 297 /* LoadFirmware() is requesting the read only normal/dev code path */ 298 #define VBSD_LF_USE_RO_NORMAL 0x00000008 299 /* Developer switch was enabled at boot time */ 300 #define VBSD_BOOT_DEV_SWITCH_ON 0x00000010 301 /* Recovery switch was enabled at boot time */ 302 #define VBSD_BOOT_REC_SWITCH_ON 0x00000020 303 /* Firmware write protect was enabled at boot time */ 304 #define VBSD_BOOT_FIRMWARE_WP_ENABLED 0x00000040 305 /* Boot is a S3->S0 resume, not a S5->S0 normal boot */ 306 #define VBSD_BOOT_S3_RESUME 0x00000100 307 /* Read-only firmware supports the normal/developer code path */ 308 #define VBSD_BOOT_RO_NORMAL_SUPPORT 0x00000200 309 /* VbInit() was told that the system has a virtual dev-switch */ 310 #define VBSD_HONOR_VIRT_DEV_SWITCH 0x00000400 311 /* VbInit() was told the system supports EC software sync */ 312 #define VBSD_EC_SOFTWARE_SYNC 0x00000800 313 /* VbInit() was told that the EC firmware is slow to update */ 314 #define VBSD_EC_SLOW_UPDATE 0x00001000 315 /* Firmware software write protect was enabled at boot time */ 316 #define VBSD_BOOT_FIRMWARE_SW_WP_ENABLED 0x00002000 317 /* VbInit() was told that the recovery button is a virtual one */ 318 #define VBSD_BOOT_REC_SWITCH_VIRTUAL 0x00004000 319 /* Firmware used vboot2 for firmware selection */ 320 #define VBSD_BOOT_FIRMWARE_VBOOT2 0x00008000 321 /* Firmware needs VGA Option ROM to display screens */ 322 #define VBSD_OPROM_MATTERS 0x00010000 323 /* Firmware has loaded the VGA Option ROM */ 324 #define VBSD_OPROM_LOADED 0x00020000 325 326 /* 327 * Supported flags by header version. It's ok to add new flags while keeping 328 * struct version 2 as long as flag-NOT-present is the correct value for 329 * existing hardware (Stumpy/Lumpy). 330 */ 331 #define VBSD_FLAGS_VERSION_1 0x00000007 /* Alex, ZGB */ 332 #define VBSD_FLAGS_VERSION_2 0x00000F7F 333 334 /* Result codes for VbSharedDataHeader.check_fw_a_result (and b_result) */ 335 #define VBSD_LF_CHECK_NOT_DONE 0 336 #define VBSD_LF_CHECK_DEV_MISMATCH 1 337 #define VBSD_LF_CHECK_REC_MISMATCH 2 338 #define VBSD_LF_CHECK_VERIFY_KEYBLOCK 3 339 #define VBSD_LF_CHECK_KEY_ROLLBACK 4 340 #define VBSD_LF_CHECK_DATA_KEY_PARSE 5 341 #define VBSD_LF_CHECK_VERIFY_PREAMBLE 6 342 #define VBSD_LF_CHECK_FW_ROLLBACK 7 343 #define VBSD_LF_CHECK_HEADER_VALID 8 344 #define VBSD_LF_CHECK_GET_FW_BODY 9 345 #define VBSD_LF_CHECK_HASH_WRONG_SIZE 10 346 #define VBSD_LF_CHECK_VERIFY_BODY 11 347 #define VBSD_LF_CHECK_VALID 12 348 /* 349 * Read-only normal path requested by firmware preamble, but unsupported by 350 * firmware. 351 */ 352 #define VBSD_LF_CHECK_NO_RO_NORMAL 13 353 354 /* Boot mode for VbSharedDataHeader.lk_boot_mode */ 355 #define VBSD_LK_BOOT_MODE_RECOVERY 0 356 #define VBSD_LK_BOOT_MODE_NORMAL 1 357 #define VBSD_LK_BOOT_MODE_DEVELOPER 2 358 359 /* Flags for VbSharedDataKernelPart.flags */ 360 #define VBSD_LKP_FLAG_KEY_BLOCK_VALID 0x01 361 362 /* Result codes for VbSharedDataKernelPart.check_result */ 363 #define VBSD_LKP_CHECK_NOT_DONE 0 364 #define VBSD_LKP_CHECK_TOO_SMALL 1 365 #define VBSD_LKP_CHECK_READ_START 2 366 #define VBSD_LKP_CHECK_KEY_BLOCK_SIG 3 367 #define VBSD_LKP_CHECK_KEY_BLOCK_HASH 4 368 #define VBSD_LKP_CHECK_DEV_MISMATCH 5 369 #define VBSD_LKP_CHECK_REC_MISMATCH 6 370 #define VBSD_LKP_CHECK_KEY_ROLLBACK 7 371 #define VBSD_LKP_CHECK_DATA_KEY_PARSE 8 372 #define VBSD_LKP_CHECK_VERIFY_PREAMBLE 9 373 #define VBSD_LKP_CHECK_KERNEL_ROLLBACK 10 374 #define VBSD_LKP_CHECK_PREAMBLE_VALID 11 375 /* 376 * Body load address check is omitted; this result code is deprecated and not 377 * used anywhere in the codebase. 378 */ 379 #define VBSD_LKP_CHECK_BODY_ADDRESS 12 380 #define VBSD_LKP_CHECK_BODY_OFFSET 13 381 #define VBSD_LKP_CHECK_SELF_SIGNED 14 382 #define VBSD_LKP_CHECK_BODY_EXCEEDS_MEM 15 383 #define VBSD_LKP_CHECK_BODY_EXCEEDS_PART 16 384 #define VBSD_LKP_CHECK_READ_DATA 17 385 #define VBSD_LKP_CHECK_VERIFY_DATA 18 386 #define VBSD_LKP_CHECK_KERNEL_GOOD 19 387 388 /* Information about a single kernel partition check in LoadKernel() */ 389 typedef struct VbSharedDataKernelPart { 390 uint64_t sector_start; /* Start sector of partition */ 391 uint64_t sector_count; /* Sector count of partition */ 392 uint32_t combined_version; /* Combined key+kernel version */ 393 uint8_t gpt_index; /* Index of partition in GPT */ 394 uint8_t check_result; /* Check result; see VBSD_LKP_CHECK_* */ 395 uint8_t flags; /* Flags (see VBSD_LKP_FLAG_* */ 396 uint8_t reserved0; /* Reserved for padding */ 397 } VbSharedDataKernelPart; 398 399 /* Number of kernel partitions to track per call. Must be power of 2. */ 400 #define VBSD_MAX_KERNEL_PARTS 8 401 402 /* Flags for VbSharedDataKernelCall.flags */ 403 /* Error initializing TPM in recovery mode */ 404 #define VBSD_LK_FLAG_REC_TPM_INIT_ERROR 0x00000001 405 406 /* Result codes for VbSharedDataKernelCall.check_result */ 407 #define VBSD_LKC_CHECK_NOT_DONE 0 408 #define VBSD_LKC_CHECK_DEV_SWITCH_MISMATCH 1 409 #define VBSD_LKC_CHECK_GPT_READ_ERROR 2 410 #define VBSD_LKC_CHECK_GPT_PARSE_ERROR 3 411 #define VBSD_LKC_CHECK_GOOD_PARTITION 4 412 #define VBSD_LKC_CHECK_INVALID_PARTITIONS 5 413 #define VBSD_LKC_CHECK_NO_PARTITIONS 6 414 415 /* Information about a single call to LoadKernel() */ 416 typedef struct VbSharedDataKernelCall { 417 /* Bottom 32 bits of flags passed in LoadKernelParams.boot_flags */ 418 uint32_t boot_flags; 419 /* Debug flags; see VBSD_LK_FLAG_* */ 420 uint32_t flags; 421 /* Number of sectors on drive */ 422 uint64_t sector_count; 423 /* Sector size in bytes */ 424 uint32_t sector_size; 425 /* Check result; see VBSD_LKC_CHECK_* */ 426 uint8_t check_result; 427 /* Boot mode for LoadKernel(); see VBSD_LK_BOOT_MODE_* constants */ 428 uint8_t boot_mode; 429 /* Test error number, if non-zero */ 430 uint8_t test_error_num; 431 /* Return code from LoadKernel() */ 432 uint8_t return_code; 433 /* Number of kernel partitions found */ 434 uint8_t kernel_parts_found; 435 /* Reserved for padding */ 436 uint8_t reserved0[7]; 437 /* Data on kernels */ 438 VbSharedDataKernelPart parts[VBSD_MAX_KERNEL_PARTS]; 439 } VbSharedDataKernelCall; 440 441 /* Number of kernel calls to track. Must be power of 2. */ 442 #define VBSD_MAX_KERNEL_CALLS 4 443 444 /* 445 * Data shared between LoadFirmware(), LoadKernel(), and OS. 446 * 447 * The boot process is: 448 * 1) Caller allocates buffer, at least VB_SHARED_DATA_MIN bytes, ideally 449 * VB_SHARED_DATA_REC_SIZE bytes. 450 * 2) If non-recovery boot, this is passed to LoadFirmware(), which 451 * initializes the buffer, adding this header and some data. 452 * 3) Buffer is passed to LoadKernel(). If this is a recovery boot, 453 * LoadKernel() initializes the buffer, adding this header. Regardless 454 * of boot type, LoadKernel() adds some data to the buffer. 455 * 4) Caller makes data available to the OS in a platform-dependent manner. 456 * For example, via ACPI or ATAGs. 457 */ 458 typedef struct VbSharedDataHeader { 459 /* Fields present in version 1 */ 460 /* Magic number for struct (VB_SHARED_DATA_MAGIC) */ 461 uint32_t magic; 462 /* Version of this structure */ 463 uint32_t struct_version; 464 /* Size of this structure in bytes */ 465 uint64_t struct_size; 466 /* Size of shared data buffer in bytes */ 467 uint64_t data_size; 468 /* Amount of shared data used so far */ 469 uint64_t data_used; 470 /* Flags */ 471 uint32_t flags; 472 /* Reserved for padding */ 473 uint32_t reserved0; 474 /* Kernel subkey, from firmware */ 475 VbPublicKey kernel_subkey; 476 /* Offset of kernel subkey data from start of this struct */ 477 uint64_t kernel_subkey_data_offset; 478 /* Size of kernel subkey data */ 479 uint64_t kernel_subkey_data_size; 480 481 /* 482 * Timer values from VbExGetTimer(). Unused values are set to 0. Note 483 * that these are now the enter/exit times for the wrapper API entry 484 * points; see crosbug.com/17018. */ 485 /* VbInit() enter/exit */ 486 uint64_t timer_vb_init_enter; 487 uint64_t timer_vb_init_exit; 488 /* VbSelectFirmware() enter/exit */ 489 uint64_t timer_vb_select_firmware_enter; 490 uint64_t timer_vb_select_firmware_exit; 491 /* VbSelectAndLoadKernel() enter/exit */ 492 uint64_t timer_vb_select_and_load_kernel_enter; 493 uint64_t timer_vb_select_and_load_kernel_exit; 494 495 /* Information stored in TPM, as retrieved by firmware */ 496 /* Current firmware version in TPM */ 497 uint32_t fw_version_tpm; 498 /* Current kernel version in TPM */ 499 uint32_t kernel_version_tpm; 500 501 /* Debugging information from LoadFirmware() */ 502 /* Result of checking RW firmware A and B */ 503 uint8_t check_fw_a_result; 504 uint8_t check_fw_b_result; 505 /* Firmware index returned by LoadFirmware() or 0xFF if failure */ 506 uint8_t firmware_index; 507 /* Reserved for padding */ 508 uint8_t reserved1; 509 /* Firmware TPM version at start of VbSelectFirmware() */ 510 uint32_t fw_version_tpm_start; 511 /* Firmware lowest version found */ 512 uint32_t fw_version_lowest; 513 514 /* Debugging information from LoadKernel() */ 515 /* Number of times LoadKernel() called */ 516 uint32_t lk_call_count; 517 /* Info on calls */ 518 VbSharedDataKernelCall lk_calls[VBSD_MAX_KERNEL_CALLS]; 519 520 /* 521 * Offset and size of supplemental kernel data. Reserve space for 522 * these fields now, so that future LoadKernel() versions can store 523 * information there without needing to shift down whatever data the 524 * original LoadFirmware() might have put immediately following its 525 * VbSharedDataHeader. 526 */ 527 uint64_t kernel_supplemental_offset; 528 uint64_t kernel_supplemental_size; 529 530 /* 531 * Fields added in version 2. Before accessing, make sure that 532 * struct_version >= 2 533 */ 534 /* Recovery reason for current boot */ 535 uint8_t recovery_reason; 536 /* Reserved for padding */ 537 uint8_t reserved2[7]; 538 /* Flags from firmware keyblock */ 539 uint64_t fw_keyblock_flags; 540 /* Kernel TPM version at start of VbSelectAndLoadKernel() */ 541 uint32_t kernel_version_tpm_start; 542 /* Kernel lowest version found */ 543 uint32_t kernel_version_lowest; 544 545 /* 546 * After read-only firmware which uses version 2 is released, any 547 * additional fields must be added below, and the struct version must 548 * be increased. Before reading/writing those fields, make sure that 549 * the struct being accessed is at least version 3. 550 * 551 * It's always ok for an older firmware to access a newer struct, since 552 * all the fields it knows about are present. Newer firmware needs to 553 * use reasonable defaults when accessing older structs. 554 */ 555 } __attribute__((packed)) VbSharedDataHeader; 556 557 /* 558 * Size of VbSharedDataheader for each version 559 * 560 * TODO: crossystem needs not to fail if called on a v1 system where 561 * sizeof(VbSharedDataHeader) was smaller 562 */ 563 #define VB_SHARED_DATA_HEADER_SIZE_V1 1072 564 #define VB_SHARED_DATA_HEADER_SIZE_V2 1096 565 566 #define VB_SHARED_DATA_VERSION 2 /* Version for struct_version */ 567 568 #endif /* VBOOT_REFERENCE_VBOOT_STRUCT_H_ */ 569