| /* SPDX-License-Identifier: GPL-2.0-only */ |
| /* This file is part of the coreboot project. */ |
| |
| #include <security/vboot/antirollback.h> |
| #include <program_loading.h> |
| #include <security/vboot/vboot_common.h> |
| #include <vb2_api.h> |
| #include <security/tpm/tss.h> |
| #include <fsp/memory_init.h> |
| #include <console/console.h> |
| #include <string.h> |
| |
| void mrc_cache_update_hash(const uint8_t *data, size_t size) |
| { |
| uint8_t data_hash[VB2_SHA256_DIGEST_SIZE]; |
| static const uint8_t dead_hash[VB2_SHA256_DIGEST_SIZE] = { |
| 0xba, 0xad, 0xda, 0x1a, /* BAADDA1A */ |
| 0xde, 0xad, 0xde, 0xad, /* DEADDEAD */ |
| 0xde, 0xad, 0xda, 0x1a, /* DEADDA1A */ |
| 0xba, 0xad, 0xba, 0xad, /* BAADBAAD */ |
| 0xba, 0xad, 0xda, 0x1a, /* BAADDA1A */ |
| 0xde, 0xad, 0xde, 0xad, /* DEADDEAD */ |
| 0xde, 0xad, 0xda, 0x1a, /* DEADDA1A */ |
| 0xba, 0xad, 0xba, 0xad, /* BAADBAAD */ |
| }; |
| const uint8_t *hash_ptr = data_hash; |
| |
| /* We do not store normal mode data hash in TPM. */ |
| if (!vboot_recovery_mode_enabled()) |
| return; |
| |
| /* Initialize TPM driver. */ |
| if (tlcl_lib_init() != VB2_SUCCESS) { |
| printk(BIOS_ERR, "MRC: TPM driver initialization failed.\n"); |
| return; |
| } |
| |
| /* Calculate hash of data generated by MRC. */ |
| if (vb2_digest_buffer(data, size, VB2_HASH_SHA256, data_hash, |
| sizeof(data_hash))) { |
| printk(BIOS_ERR, "MRC: SHA-256 calculation failed for data. " |
| "Not updating TPM hash space.\n"); |
| /* |
| * Since data is being updated in recovery cache, the hash |
| * currently stored in TPM recovery hash space is no longer |
| * valid. If we are not able to calculate hash of the data being |
| * updated, reset all the bits in TPM recovery hash space to |
| * pre-defined hash pattern. |
| */ |
| hash_ptr = dead_hash; |
| } |
| |
| /* Write hash of data to TPM space. */ |
| if (antirollback_write_space_rec_hash(hash_ptr, VB2_SHA256_DIGEST_SIZE) |
| != TPM_SUCCESS) { |
| printk(BIOS_ERR, "MRC: Could not save hash to TPM.\n"); |
| return; |
| } |
| |
| printk(BIOS_INFO, "MRC: TPM MRC hash updated successfully.\n"); |
| } |
| |
| int mrc_cache_verify_hash(const uint8_t *data, size_t size) |
| { |
| uint8_t data_hash[VB2_SHA256_DIGEST_SIZE]; |
| uint8_t tpm_hash[VB2_SHA256_DIGEST_SIZE]; |
| |
| /* We do not store normal mode data hash in TPM. */ |
| if (!vboot_recovery_mode_enabled()) |
| return 1; |
| |
| /* Calculate hash of data read from RECOVERY_MRC_CACHE. */ |
| if (vb2_digest_buffer(data, size, VB2_HASH_SHA256, data_hash, |
| sizeof(data_hash))) { |
| printk(BIOS_ERR, "MRC: SHA-256 calculation failed for data.\n"); |
| return 0; |
| } |
| |
| /* Initialize TPM driver. */ |
| if (tlcl_lib_init() != VB2_SUCCESS) { |
| printk(BIOS_ERR, "MRC: TPM driver initialization failed.\n"); |
| return 0; |
| } |
| |
| /* Read hash of MRC data saved in TPM. */ |
| if (antirollback_read_space_rec_hash(tpm_hash, sizeof(tpm_hash)) |
| != TPM_SUCCESS) { |
| printk(BIOS_ERR, "MRC: Could not read hash from TPM.\n"); |
| return 0; |
| } |
| |
| if (memcmp(tpm_hash, data_hash, sizeof(tpm_hash))) { |
| printk(BIOS_ERR, "MRC: Hash comparison failed.\n"); |
| return 0; |
| } |
| |
| printk(BIOS_INFO, "MRC: Hash comparison successful. " |
| "Using data from RECOVERY_MRC_CACHE\n"); |
| return 1; |
| } |