| /* Copyright (c) 2012 The Chromium OS Authors. All rights reserved. |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| * |
| * Functions for loading a kernel from disk. |
| * (Firmware portion) |
| */ |
| |
| |
| #include "cgptlib.h" |
| #include "cgptlib_internal.h" |
| #include "gbb_header.h" |
| #include "load_kernel_fw.h" |
| #include "utility.h" |
| #include "vboot_api.h" |
| #include "vboot_common.h" |
| #include "vboot_kernel.h" |
| |
| #define KBUF_SIZE 65536 /* Bytes to read at start of kernel partition */ |
| #define LOWEST_TPM_VERSION 0xffffffff |
| |
| typedef enum BootMode { |
| kBootRecovery = 0, /* Recovery firmware, regardless of dev switch position */ |
| kBootNormal = 1, /* Normal boot - kernel must be verified */ |
| kBootDev = 2 /* Developer boot - self-signed kernel ok */ |
| } BootMode; |
| |
| |
| /* Allocates and reads GPT data from the drive. The sector_bytes and |
| * drive_sectors fields should be filled on input. The primary and |
| * secondary header and entries are filled on output. |
| * |
| * Returns 0 if successful, 1 if error. */ |
| int AllocAndReadGptData(VbExDiskHandle_t disk_handle, GptData* gptdata) { |
| |
| uint64_t entries_sectors = TOTAL_ENTRIES_SIZE / gptdata->sector_bytes; |
| |
| /* No data to be written yet */ |
| gptdata->modified = 0; |
| |
| /* Allocate all buffers */ |
| gptdata->primary_header = (uint8_t*)VbExMalloc(gptdata->sector_bytes); |
| gptdata->secondary_header = (uint8_t*)VbExMalloc(gptdata->sector_bytes); |
| gptdata->primary_entries = (uint8_t*)VbExMalloc(TOTAL_ENTRIES_SIZE); |
| gptdata->secondary_entries = (uint8_t*)VbExMalloc(TOTAL_ENTRIES_SIZE); |
| |
| if (gptdata->primary_header == NULL || gptdata->secondary_header == NULL || |
| gptdata->primary_entries == NULL || gptdata->secondary_entries == NULL) |
| return 1; |
| |
| /* Read data from the drive, skipping the protective MBR */ |
| if (0 != VbExDiskRead(disk_handle, 1, 1, gptdata->primary_header)) |
| return 1; |
| if (0 != VbExDiskRead(disk_handle, 2, entries_sectors, |
| gptdata->primary_entries)) |
| return 1; |
| if (0 != VbExDiskRead(disk_handle, |
| gptdata->drive_sectors - entries_sectors - 1, |
| entries_sectors, gptdata->secondary_entries)) |
| return 1; |
| if (0 != VbExDiskRead(disk_handle, gptdata->drive_sectors - 1, 1, |
| gptdata->secondary_header)) |
| return 1; |
| |
| return 0; |
| } |
| |
| |
| /* Writes any changes for the GPT data back to the drive, then frees |
| * the buffers. |
| * |
| * Returns 0 if successful, 1 if error. */ |
| int WriteAndFreeGptData(VbExDiskHandle_t disk_handle, GptData* gptdata) { |
| |
| uint64_t entries_sectors = TOTAL_ENTRIES_SIZE / gptdata->sector_bytes; |
| |
| if (gptdata->primary_header) { |
| if (gptdata->modified & GPT_MODIFIED_HEADER1) { |
| VBDEBUG(("Updating GPT header 1\n")); |
| if (0 != VbExDiskWrite(disk_handle, 1, 1, gptdata->primary_header)) |
| return 1; |
| } |
| VbExFree(gptdata->primary_header); |
| } |
| |
| if (gptdata->primary_entries) { |
| if (gptdata->modified & GPT_MODIFIED_ENTRIES1) { |
| VBDEBUG(("Updating GPT entries 1\n")); |
| if (0 != VbExDiskWrite(disk_handle, 2, entries_sectors, |
| gptdata->primary_entries)) |
| return 1; |
| } |
| VbExFree(gptdata->primary_entries); |
| } |
| |
| if (gptdata->secondary_entries) { |
| if (gptdata->modified & GPT_MODIFIED_ENTRIES2) { |
| VBDEBUG(("Updating GPT header 2\n")); |
| if (0 != VbExDiskWrite(disk_handle, |
| gptdata->drive_sectors - entries_sectors - 1, |
| entries_sectors, gptdata->secondary_entries)) |
| return 1; |
| } |
| VbExFree(gptdata->secondary_entries); |
| } |
| |
| if (gptdata->secondary_header) { |
| if (gptdata->modified & GPT_MODIFIED_HEADER2) { |
| VBDEBUG(("Updating GPT entries 2\n")); |
| if (0 != VbExDiskWrite(disk_handle, gptdata->drive_sectors - 1, 1, |
| gptdata->secondary_header)) |
| return 1; |
| } |
| VbExFree(gptdata->secondary_header); |
| } |
| |
| /* Success */ |
| return 0; |
| } |
| |
| /* disable MSVC warning on const logical expression (as in } while(0);) */ |
| __pragma(warning(disable: 4127)) |
| |
| |
| VbError_t LoadKernel(LoadKernelParams* params) { |
| VbSharedDataHeader* shared = (VbSharedDataHeader*)params->shared_data_blob; |
| VbSharedDataKernelCall* shcall = NULL; |
| VbNvContext* vnc = params->nv_context; |
| GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)params->gbb_data; |
| VbPublicKey* kernel_subkey; |
| GptData gpt; |
| uint64_t part_start, part_size; |
| uint64_t blba; |
| uint64_t kbuf_sectors; |
| uint8_t* kbuf = NULL; |
| int found_partitions = 0; |
| int good_partition = -1; |
| int good_partition_key_block_valid = 0; |
| uint32_t lowest_version = LOWEST_TPM_VERSION; |
| int rec_switch, dev_switch; |
| BootMode boot_mode; |
| uint32_t require_official_os = 0; |
| |
| VbError_t retval = VBERROR_UNKNOWN; |
| int recovery = VBNV_RECOVERY_RO_UNSPECIFIED; |
| |
| /* Sanity Checks */ |
| if (!params || |
| !params->bytes_per_lba || |
| !params->ending_lba || |
| !params->kernel_buffer || |
| !params->kernel_buffer_size) { |
| VBDEBUG(("LoadKernel() called with invalid params\n")); |
| retval = VBERROR_INVALID_PARAMETER; |
| goto LoadKernelExit; |
| } |
| |
| /* Clear output params in case we fail */ |
| params->partition_number = 0; |
| params->bootloader_address = 0; |
| params->bootloader_size = 0; |
| |
| /* Calculate switch positions and boot mode */ |
| rec_switch = (BOOT_FLAG_RECOVERY & params->boot_flags ? 1 : 0); |
| dev_switch = (BOOT_FLAG_DEVELOPER & params->boot_flags ? 1 : 0); |
| if (rec_switch) { |
| boot_mode = kBootRecovery; |
| } else if (dev_switch) { |
| boot_mode = kBootDev; |
| VbNvGet(vnc, VBNV_DEV_BOOT_SIGNED_ONLY, &require_official_os); |
| } else { |
| boot_mode = kBootNormal; |
| } |
| |
| /* Set up tracking for this call. This wraps around if called many times, |
| * so we need to initialize the call entry each time. */ |
| shcall = shared->lk_calls + (shared->lk_call_count |
| & (VBSD_MAX_KERNEL_CALLS - 1)); |
| Memset(shcall, 0, sizeof(VbSharedDataKernelCall)); |
| shcall->boot_flags = (uint32_t)params->boot_flags; |
| shcall->boot_mode = boot_mode; |
| shcall->sector_size = (uint32_t)params->bytes_per_lba; |
| shcall->sector_count = params->ending_lba + 1; |
| shared->lk_call_count++; |
| |
| /* Initialization */ |
| blba = params->bytes_per_lba; |
| kbuf_sectors = KBUF_SIZE / blba; |
| if (0 == kbuf_sectors) { |
| VBDEBUG(("LoadKernel() called with sector size > KBUF_SIZE\n")); |
| retval = VBERROR_INVALID_PARAMETER; |
| goto LoadKernelExit; |
| } |
| |
| if (kBootRecovery == boot_mode) { |
| /* Use the recovery key to verify the kernel */ |
| kernel_subkey = (VbPublicKey*)((uint8_t*)gbb + gbb->recovery_key_offset); |
| } else { |
| /* Use the kernel subkey passed from LoadFirmware(). */ |
| kernel_subkey = &shared->kernel_subkey; |
| } |
| |
| do { |
| /* Read GPT data */ |
| gpt.sector_bytes = (uint32_t)blba; |
| gpt.drive_sectors = params->ending_lba + 1; |
| if (0 != AllocAndReadGptData(params->disk_handle, &gpt)) { |
| VBDEBUG(("Unable to read GPT data\n")); |
| shcall->check_result = VBSD_LKC_CHECK_GPT_READ_ERROR; |
| break; |
| } |
| |
| /* Initialize GPT library */ |
| if (GPT_SUCCESS != GptInit(&gpt)) { |
| VBDEBUG(("Error parsing GPT\n")); |
| shcall->check_result = VBSD_LKC_CHECK_GPT_PARSE_ERROR; |
| break; |
| } |
| |
| /* Allocate kernel header buffers */ |
| kbuf = (uint8_t*)VbExMalloc(KBUF_SIZE); |
| if (!kbuf) |
| break; |
| |
| /* Loop over candidate kernel partitions */ |
| while (GPT_SUCCESS == GptNextKernelEntry(&gpt, &part_start, &part_size)) { |
| VbSharedDataKernelPart* shpart = NULL; |
| VbKeyBlockHeader* key_block; |
| VbKernelPreambleHeader* preamble; |
| RSAPublicKey* data_key = NULL; |
| uint64_t key_version; |
| uint32_t combined_version; |
| uint64_t body_offset; |
| uint64_t body_offset_sectors; |
| uint64_t body_sectors; |
| int key_block_valid = 1; |
| |
| VBDEBUG(("Found kernel entry at %" PRIu64 " size %" PRIu64 "\n", |
| part_start, part_size)); |
| |
| /* Set up tracking for this partition. This wraps around if called |
| * many times, so initialize the partition entry each time. */ |
| shpart = shcall->parts + (shcall->kernel_parts_found |
| & (VBSD_MAX_KERNEL_PARTS - 1)); |
| Memset(shpart, 0, sizeof(VbSharedDataKernelPart)); |
| shpart->sector_start = part_start; |
| shpart->sector_count = part_size; |
| /* TODO: GPT partitions start at 1, but cgptlib starts them at 0. |
| * Adjust here, until cgptlib is fixed. */ |
| shpart->gpt_index = (uint8_t)(gpt.current_kernel + 1); |
| shcall->kernel_parts_found++; |
| |
| /* Found at least one kernel partition. */ |
| found_partitions++; |
| |
| /* Read the first part of the kernel partition. */ |
| if (part_size < kbuf_sectors) { |
| VBDEBUG(("Partition too small to hold kernel.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_TOO_SMALL; |
| goto bad_kernel; |
| } |
| |
| if (0 != VbExDiskRead(params->disk_handle, part_start, kbuf_sectors, |
| kbuf)) { |
| VBDEBUG(("Unable to read start of partition.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_READ_START; |
| goto bad_kernel; |
| } |
| |
| /* Verify the key block. */ |
| key_block = (VbKeyBlockHeader*)kbuf; |
| if (0 != KeyBlockVerify(key_block, KBUF_SIZE, kernel_subkey, 0)) { |
| VBDEBUG(("Verifying key block signature failed.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_KEY_BLOCK_SIG; |
| |
| key_block_valid = 0; |
| |
| /* If we're not in developer mode, this kernel is bad. */ |
| if (kBootDev != boot_mode) |
| goto bad_kernel; |
| |
| /* In developer mode, we can explictly disallow self-signed kernels */ |
| if (require_official_os) { |
| VBDEBUG(("Self-signed custom kernels are not enabled.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_SELF_SIGNED; |
| goto bad_kernel; |
| } |
| |
| /* Allow the kernel if the SHA-512 hash of the key block is valid. */ |
| if (0 != KeyBlockVerify(key_block, KBUF_SIZE, kernel_subkey, 1)) { |
| VBDEBUG(("Verifying key block hash failed.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_KEY_BLOCK_HASH; |
| goto bad_kernel; |
| } |
| } |
| |
| /* Check the key block flags against the current boot mode. */ |
| if (!(key_block->key_block_flags & |
| (dev_switch ? KEY_BLOCK_FLAG_DEVELOPER_1 : |
| KEY_BLOCK_FLAG_DEVELOPER_0))) { |
| VBDEBUG(("Key block developer flag mismatch.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_DEV_MISMATCH; |
| key_block_valid = 0; |
| } |
| if (!(key_block->key_block_flags & |
| (rec_switch ? KEY_BLOCK_FLAG_RECOVERY_1 : |
| KEY_BLOCK_FLAG_RECOVERY_0))) { |
| VBDEBUG(("Key block recovery flag mismatch.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_REC_MISMATCH; |
| key_block_valid = 0; |
| } |
| |
| /* Check for rollback of key version except in recovery mode. */ |
| key_version = key_block->data_key.key_version; |
| if (kBootRecovery != boot_mode) { |
| if (key_version < (shared->kernel_version_tpm >> 16)) { |
| VBDEBUG(("Key version too old.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_KEY_ROLLBACK; |
| key_block_valid = 0; |
| } |
| if (key_version > 0xFFFF) { |
| /* Key version is stored in 16 bits in the TPM, so key versions |
| * greater than 0xFFFF can't be stored properly. */ |
| VBDEBUG(("Key version > 0xFFFF.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_KEY_ROLLBACK; |
| key_block_valid = 0; |
| } |
| } |
| |
| /* If we're not in developer mode, require the key block to be valid. */ |
| if (kBootDev != boot_mode && !key_block_valid) { |
| VBDEBUG(("Key block is invalid.\n")); |
| goto bad_kernel; |
| } |
| |
| /* Get the key for preamble/data verification from the key block. */ |
| data_key = PublicKeyToRSA(&key_block->data_key); |
| if (!data_key) { |
| VBDEBUG(("Data key bad.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_DATA_KEY_PARSE; |
| goto bad_kernel; |
| } |
| |
| /* Verify the preamble, which follows the key block */ |
| preamble = (VbKernelPreambleHeader*)(kbuf + key_block->key_block_size); |
| if ((0 != VerifyKernelPreamble(preamble, |
| KBUF_SIZE - key_block->key_block_size, |
| data_key))) { |
| VBDEBUG(("Preamble verification failed.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_VERIFY_PREAMBLE; |
| goto bad_kernel; |
| } |
| |
| /* If the key block is valid and we're not in recovery mode, check for |
| * rollback of the kernel version. */ |
| combined_version = (uint32_t)((key_version << 16) | |
| (preamble->kernel_version & 0xFFFF)); |
| shpart->combined_version = combined_version; |
| if (key_block_valid && kBootRecovery != boot_mode) { |
| if (combined_version < shared->kernel_version_tpm) { |
| VBDEBUG(("Kernel version too low.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_KERNEL_ROLLBACK; |
| /* If we're not in developer mode, kernel version must be valid. */ |
| if (kBootDev != boot_mode) |
| goto bad_kernel; |
| } |
| } |
| |
| VBDEBUG(("Kernel preamble is good.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_PREAMBLE_VALID; |
| |
| /* Check for lowest version from a valid header. */ |
| if (key_block_valid && lowest_version > combined_version) |
| lowest_version = combined_version; |
| else { |
| VBDEBUG(("Key block valid: %d\n", key_block_valid)); |
| VBDEBUG(("Combined version: %u\n", (unsigned) combined_version)); |
| } |
| |
| /* If we already have a good kernel, no need to read another |
| * one; we only needed to look at the versions to check for |
| * rollback. So skip to the next kernel preamble. */ |
| if (-1 != good_partition) |
| continue; |
| |
| /* Verify kernel body starts at a multiple of the sector size. */ |
| body_offset = key_block->key_block_size + preamble->preamble_size; |
| if (0 != body_offset % blba) { |
| VBDEBUG(("Kernel body not at multiple of sector size.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_BODY_OFFSET; |
| goto bad_kernel; |
| } |
| body_offset_sectors = body_offset / blba; |
| |
| /* Verify kernel body fits in the buffer */ |
| body_sectors = (preamble->body_signature.data_size + blba - 1) / blba; |
| if (body_sectors * blba > params->kernel_buffer_size) { |
| VBDEBUG(("Kernel body doesn't fit in memory.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_BODY_EXCEEDS_MEM; |
| goto bad_kernel; |
| } |
| |
| /* Verify kernel body fits in the partition */ |
| if (body_offset_sectors + body_sectors > part_size) { |
| VBDEBUG(("Kernel body doesn't fit in partition.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_BODY_EXCEEDS_PART; |
| goto bad_kernel; |
| } |
| |
| /* Read the kernel data */ |
| VBPERFSTART("VB_RKD"); |
| if (0 != VbExDiskRead(params->disk_handle, |
| part_start + body_offset_sectors, |
| body_sectors, params->kernel_buffer)) { |
| VBDEBUG(("Unable to read kernel data.\n")); |
| VBPERFEND("VB_RKD"); |
| shpart->check_result = VBSD_LKP_CHECK_READ_DATA; |
| goto bad_kernel; |
| } |
| VBPERFEND("VB_RKD"); |
| |
| /* Verify kernel data */ |
| if (0 != VerifyData((const uint8_t*)params->kernel_buffer, |
| params->kernel_buffer_size, |
| &preamble->body_signature, data_key)) { |
| VBDEBUG(("Kernel data verification failed.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_VERIFY_DATA; |
| goto bad_kernel; |
| } |
| |
| /* Done with the kernel signing key, so can free it now */ |
| RSAPublicKeyFree(data_key); |
| data_key = NULL; |
| |
| /* If we're still here, the kernel is valid. */ |
| /* Save the first good partition we find; that's the one we'll boot */ |
| VBDEBUG(("Partition is good.\n")); |
| shpart->check_result = VBSD_LKP_CHECK_KERNEL_GOOD; |
| if (key_block_valid) |
| shpart->flags |= VBSD_LKP_FLAG_KEY_BLOCK_VALID; |
| |
| good_partition_key_block_valid = key_block_valid; |
| /* TODO: GPT partitions start at 1, but cgptlib starts them at 0. |
| * Adjust here, until cgptlib is fixed. */ |
| good_partition = gpt.current_kernel + 1; |
| params->partition_number = gpt.current_kernel + 1; |
| GetCurrentKernelUniqueGuid(&gpt, ¶ms->partition_guid); |
| /* TODO: GetCurrentKernelUniqueGuid() should take a destination size, or |
| * the dest should be a struct, so we know it's big enough. */ |
| params->bootloader_address = preamble->bootloader_address; |
| params->bootloader_size = preamble->bootloader_size; |
| |
| /* Update GPT to note this is the kernel we're trying */ |
| GptUpdateKernelEntry(&gpt, GPT_UPDATE_ENTRY_TRY); |
| |
| /* If we're in recovery mode or we're about to boot a dev-signed kernel, |
| * there's no rollback protection, so we can stop at the first valid |
| * kernel. */ |
| if (kBootRecovery == boot_mode || !key_block_valid) { |
| VBDEBUG(("In recovery mode or dev-signed kernel\n")); |
| break; |
| } |
| |
| /* Otherwise, we do care about the key index in the TPM. If the good |
| * partition's key version is the same as the tpm, then the TPM doesn't |
| * need updating; we can stop now. Otherwise, we'll check all the other |
| * headers to see if they contain a newer key. */ |
| if (combined_version == shared->kernel_version_tpm) { |
| VBDEBUG(("Same kernel version\n")); |
| break; |
| } |
| |
| /* Continue, so that we skip the error handling code below */ |
| continue; |
| |
| bad_kernel: |
| /* Handle errors parsing this kernel */ |
| if (NULL != data_key) |
| RSAPublicKeyFree(data_key); |
| |
| VBDEBUG(("Marking kernel as invalid.\n")); |
| GptUpdateKernelEntry(&gpt, GPT_UPDATE_ENTRY_BAD); |
| |
| |
| } /* while(GptNextKernelEntry) */ |
| } while(0); |
| |
| /* Free kernel buffer */ |
| if (kbuf) |
| VbExFree(kbuf); |
| |
| /* Write and free GPT data */ |
| WriteAndFreeGptData(params->disk_handle, &gpt); |
| |
| /* Handle finding a good partition */ |
| if (good_partition >= 0) { |
| VBDEBUG(("Good_partition >= 0\n")); |
| shcall->check_result = VBSD_LKC_CHECK_GOOD_PARTITION; |
| shared->kernel_version_lowest = lowest_version; |
| /* Sanity check - only store a new TPM version if we found one. |
| * If lowest_version is still at its initial value, we didn't find |
| * one; for example, we're in developer mode and just didn't look. */ |
| if (lowest_version != LOWEST_TPM_VERSION && |
| lowest_version > shared->kernel_version_tpm) |
| shared->kernel_version_tpm = lowest_version; |
| |
| /* Success! */ |
| retval = VBERROR_SUCCESS; |
| } else if (found_partitions > 0) { |
| shcall->check_result = VBSD_LKC_CHECK_INVALID_PARTITIONS; |
| recovery = VBNV_RECOVERY_RW_INVALID_OS; |
| retval = VBERROR_INVALID_KERNEL_FOUND; |
| } else { |
| shcall->check_result = VBSD_LKC_CHECK_NO_PARTITIONS; |
| recovery = VBNV_RECOVERY_RW_NO_OS; |
| retval = VBERROR_NO_KERNEL_FOUND; |
| } |
| |
| LoadKernelExit: |
| |
| /* Store recovery request, if any */ |
| VbNvSet(vnc, VBNV_RECOVERY_REQUEST, VBERROR_SUCCESS != retval ? |
| recovery : VBNV_RECOVERY_NOT_REQUESTED); |
| |
| /* If LoadKernel was called with bad parameters, |
| * shcall may not be initialized. */ |
| if (shcall) |
| shcall->return_code = (uint8_t)retval; |
| |
| /* Save whether the good partition's key block was fully verified */ |
| if (good_partition_key_block_valid) |
| shared->flags |= VBSD_KERNEL_KEY_VERIFIED; |
| |
| /* Store how much shared data we used, if any */ |
| params->shared_data_size = shared->data_used; |
| |
| return retval; |
| } |