/* SPDX-License-Identifier: BSD-3-Clause */ /* * Functions for querying, manipulating and locking rollback indices * stored in the TPM NVRAM. */ #include #include #include #include #include #include #include #include #define VBDEBUG(format, args...) \ printk(BIOS_INFO, "%s():%d: " format, __func__, __LINE__, ## args) #define RETURN_ON_FAILURE(tpm_cmd) do { \ uint32_t result_; \ if ((result_ = (tpm_cmd)) != TPM_SUCCESS) { \ VBDEBUG("Antirollback: %08x returned by " #tpm_cmd \ "\n", (int)result_); \ return result_; \ } \ } while (0) static uint32_t safe_write(uint32_t index, const void *data, uint32_t length); static uint32_t read_space_firmware(struct vb2_context *ctx) { RETURN_ON_FAILURE(tlcl_read(FIRMWARE_NV_INDEX, ctx->secdata_firmware, VB2_SECDATA_FIRMWARE_SIZE)); return TPM_SUCCESS; } uint32_t antirollback_read_space_kernel(struct vb2_context *ctx) { if (!CONFIG(TPM2)) { /* * Before reading the kernel space, verify its permissions. If * the kernel space has the wrong permission, we give up. This * will need to be fixed by the recovery kernel. We will have * to worry about this because at any time (even with PP turned * off) the TPM owner can remove and redefine a PP-protected * space (but not write to it). */ uint32_t perms; RETURN_ON_FAILURE(tlcl_get_permissions(KERNEL_NV_INDEX, &perms)); if (perms != TPM_NV_PER_PPWRITE) { printk(BIOS_ERR, "TPM: invalid secdata_kernel permissions\n"); return TPM_E_CORRUPTED_STATE; } } uint8_t size = VB2_SECDATA_KERNEL_SIZE; uint32_t ret; /* Start with the version 1.0 size used by all modern cr50-boards. */ ret = tlcl_read(KERNEL_NV_INDEX, ctx->secdata_kernel, size); if (ret == TPM_E_RANGE) { /* Fallback to version 0.2(minimum) size and re-read. */ VBDEBUG("Antirollback: NV read out of range, trying min size\n"); size = VB2_SECDATA_KERNEL_MIN_SIZE; ret = tlcl_read(KERNEL_NV_INDEX, ctx->secdata_kernel, size); } RETURN_ON_FAILURE(ret); if (vb2api_secdata_kernel_check(ctx, &size) == VB2_ERROR_SECDATA_KERNEL_INCOMPLETE) /* Re-read. vboot will run the check and handle errors. */ RETURN_ON_FAILURE(tlcl_read(KERNEL_NV_INDEX, ctx->secdata_kernel, size)); return TPM_SUCCESS; } #if CONFIG(TPM2) static uint32_t read_space_mrc_hash(uint32_t index, uint8_t *data) { RETURN_ON_FAILURE(tlcl_read(index, data, HASH_NV_SIZE)); return TPM_SUCCESS; } /* * This is used to initialize the TPM space for recovery hash after defining * it. Since there is no data available to calculate hash at the point where TPM * space is defined, initialize it to all 0s. */ static const uint8_t mrc_hash_data[HASH_NV_SIZE] = { }; /* * Different sets of NVRAM space attributes apply to the "ro" spaces, * i.e. those which should not be possible to delete or modify once * the RO exits, and the rest of the NVRAM spaces. */ static const TPMA_NV ro_space_attributes = { .TPMA_NV_PPWRITE = 1, .TPMA_NV_AUTHREAD = 1, .TPMA_NV_PPREAD = 1, .TPMA_NV_PLATFORMCREATE = 1, .TPMA_NV_WRITE_STCLEAR = 1, .TPMA_NV_POLICY_DELETE = 1, }; static const TPMA_NV rw_space_attributes = { .TPMA_NV_PPWRITE = 1, .TPMA_NV_AUTHREAD = 1, .TPMA_NV_PPREAD = 1, .TPMA_NV_PLATFORMCREATE = 1, .TPMA_NV_WRITE_STCLEAR = 1, }; const static TPMA_NV rw_counter_attributes = { .TPMA_NV_AUTHWRITE = 1, .TPMA_NV_AUTHREAD = 1, .TPMA_NV_PPREAD = 1, .TPMA_NV_PPWRITE = 1, .TPMA_NV_PLATFORMCREATE = 1, .TPMA_NV_COUNTER = 1, .TPMA_NV_NO_DA = 1, .TPMA_NV_WRITE_STCLEAR = 1, }; static const TPMA_NV fwmp_attr = { .TPMA_NV_PLATFORMCREATE = 1, .TPMA_NV_OWNERWRITE = 1, .TPMA_NV_AUTHREAD = 1, .TPMA_NV_PPREAD = 1, .TPMA_NV_PPWRITE = 1, }; /* Attributes for spaces that enable zero-touch enrollment (ZTE) */ static const TPMA_NV zte_attr = { .TPMA_NV_PLATFORMCREATE = 1, .TPMA_NV_WRITEDEFINE = 1, .TPMA_NV_AUTHWRITE = 1, .TPMA_NV_AUTHREAD = 1, .TPMA_NV_PPWRITE = 1, .TPMA_NV_PPREAD = 1, .TPMA_NV_NO_DA = 1, .TPMA_NV_POLICY_DELETE = 1, }; static const TPMA_NV zte_rma_bytes_attr = { .TPMA_NV_PLATFORMCREATE = 1, .TPMA_NV_BITS = 1, .TPMA_NV_AUTHWRITE = 1, .TPMA_NV_AUTHREAD = 1, .TPMA_NV_PPWRITE = 1, .TPMA_NV_PPREAD = 1, .TPMA_NV_NO_DA = 1, .TPMA_NV_POLICY_DELETE = 1, }; /* * This policy digest was obtained using TPM2_PolicyOR on 3 digests * corresponding to a sequence of * -) TPM2_PolicyCommandCode(TPM_CC_NV_UndefineSpaceSpecial), * -) TPM2_PolicyPCR(PCR0, ). * where is * 1) all zeros = initial, unextended state: * - Value to extend to initial PCR0: * * - Resulting PCR0: * 0000000000000000000000000000000000000000000000000000000000000000 * - Policy digest for PolicyCommandCode + PolicyPCR: * 4B44FC4192DB5AD7167E0135708FD374890A06BFB56317DF01F24F2226542A3F * 2) result of extending (SHA1(0x00|0x01|0x00) | 00s to SHA256 size) * - Value to extend to initial PCR0: * 62571891215b4efc1ceab744ce59dd0b66ea6f73000000000000000000000000 * - Resulting PCR0: * 9F9EA866D3F34FE3A3112AE9CB1FBABC6FFE8CD261D42493BC6842A9E4F93B3D * - Policy digest for PolicyCommandCode + PolicyPCR: * CB5C8014E27A5F7586AAE42DB4F9776A977BCBC952CA61E33609DA2B2C329418 * 3) result of extending (SHA1(0x01|0x01|0x00) | 00s to SHA256 size) * - Value to extend to initial PCR0: * 47ec8d98366433dc002e7721c9e37d5067547937000000000000000000000000 * - Resulting PCR0: * 2A7580E5DA289546F4D2E0509CC6DE155EA131818954D36D49E027FD42B8C8F8 * - Policy digest for PolicyCommandCode + PolicyPCR: * E6EF4F0296AC3EF0F53906480985B1BE8058E0E517E5F74A5B8A415EFE339D87 * Values #2 and #3 correspond to two forms of recovery mode as extended by * vb2api_get_pcr_digest(). * As a result, the digest allows deleting the space with UndefineSpaceSpecial * at early RO stages (before extending PCR0) or from recovery mode. */ static const uint8_t pcr0_allowed_policy[] = { 0x44, 0x44, 0x79, 0x00, 0xCB, 0xB8, 0x3F, 0x5B, 0x15, 0x76, 0x56, 0x50, 0xEF, 0x96, 0x98, 0x0A, 0x2B, 0x96, 0x6E, 0xA9, 0x09, 0x04, 0x4A, 0x01, 0xB8, 0x5F, 0xA5, 0x4A, 0x96, 0xFC, 0x59, 0x84}; static const uint8_t unsatisfiable_policy[VB2_SHA256_DIGEST_SIZE] = "hmwhat if RBR beat merc in 2021"; static uint32_t define_space(const char *name, uint32_t index, uint32_t length, const TPMA_NV nv_attributes, const uint8_t *nv_policy, size_t nv_policy_size) { uint32_t rv; rv = tlcl_define_space(index, length, nv_attributes, nv_policy, nv_policy_size); if (rv == TPM_E_NV_DEFINED) { /* * Continue with writing: it may be defined, but not written * to. In that case a subsequent tlcl_read() would still return * TPM_E_BADINDEX on TPM 2.0. The cases when some non-firmware * space is defined while the firmware space is not there * should be rare (interrupted initialization), so no big harm * in writing once again even if it was written already. */ VBDEBUG("%s: %s space already exists\n", __func__, name); rv = TPM_SUCCESS; } return rv; } /* Nothing special in the TPM2 path yet. */ static uint32_t safe_write(uint32_t index, const void *data, uint32_t length) { return tlcl_write(index, data, length); } static uint32_t setup_space(const char *name, uint32_t index, const void *data, uint32_t length, const TPMA_NV nv_attributes, const uint8_t *nv_policy, size_t nv_policy_size) { uint32_t rv; rv = define_space(name, index, length, nv_attributes, nv_policy, nv_policy_size); if (rv != TPM_SUCCESS) return rv; return safe_write(index, data, length); } static uint32_t setup_firmware_space(struct vb2_context *ctx) { uint32_t firmware_space_size = vb2api_secdata_firmware_create(ctx); return setup_space("firmware", FIRMWARE_NV_INDEX, ctx->secdata_firmware, firmware_space_size, ro_space_attributes, pcr0_allowed_policy, sizeof(pcr0_allowed_policy)); } static uint32_t setup_fwmp_space(struct vb2_context *ctx) { uint32_t fwmp_space_size = vb2api_secdata_fwmp_create(ctx); return setup_space("FWMP", FWMP_NV_INDEX, ctx->secdata_fwmp, fwmp_space_size, fwmp_attr, NULL, 0); } static uint32_t setup_kernel_space(struct vb2_context *ctx) { uint32_t kernel_space_size = vb2api_secdata_kernel_create(ctx); return setup_space("kernel", KERNEL_NV_INDEX, ctx->secdata_kernel, kernel_space_size, rw_space_attributes, NULL, 0); } static uint32_t set_mrc_hash_space(uint32_t index, const uint8_t *data) { if (index == MRC_REC_HASH_NV_INDEX) { return setup_space("RO MRC Hash", index, data, HASH_NV_SIZE, ro_space_attributes, pcr0_allowed_policy, sizeof(pcr0_allowed_policy)); } else { return setup_space("RW MRC Hash", index, data, HASH_NV_SIZE, rw_space_attributes, NULL, 0); } } /** * Set up the Zero-Touch Enrollment(ZTE) related spaces. * * These spaces are not used by firmware, but we do need to initialize them. */ static uint32_t setup_zte_spaces(void) { uint32_t rv; uint64_t rma_bytes_counter_default = 0; uint8_t rma_sn_bits_default[16]; uint8_t board_id_default[12]; /* Initialize defaults: Board ID and RMA+SN Bits must be initialized to all 0xFFs. */ memset(rma_sn_bits_default, 0xFF, ARRAY_SIZE(rma_sn_bits_default)); memset(board_id_default, 0xFF, ARRAY_SIZE(board_id_default)); /* Set up RMA + SN Bits */ rv = setup_space("RMA + SN Bits", ZTE_RMA_SN_BITS_INDEX, rma_sn_bits_default, sizeof(rma_sn_bits_default), zte_attr, unsatisfiable_policy, sizeof(unsatisfiable_policy)); if (rv != TPM_SUCCESS) { VBDEBUG("%s: Failed to set up RMA + SN Bits space\n", __func__); return rv; } rv = setup_space("Board ID", ZTE_BOARD_ID_NV_INDEX, board_id_default, sizeof(board_id_default), zte_attr, unsatisfiable_policy, sizeof(unsatisfiable_policy)); if (rv != TPM_SUCCESS) { VBDEBUG("%s: Failed to set up Board ID space\n", __func__); return rv; } /* Set up RMA Bytes counter */ rv = define_space("RMA Bytes Counter", ZTE_RMA_BYTES_COUNTER_INDEX, sizeof(rma_bytes_counter_default), zte_rma_bytes_attr, unsatisfiable_policy, sizeof(unsatisfiable_policy)); if (rv != TPM_SUCCESS) { VBDEBUG("%s: Failed to define RMA Bytes space\n", __func__); return rv; } /* * Since the RMA counter has the BITS attribute, we need to call * TPM2_NV_SetBits() in order to initialize it. */ rv = tlcl_set_bits(ZTE_RMA_BYTES_COUNTER_INDEX, rma_bytes_counter_default); if (rv != TPM_SUCCESS) { VBDEBUG("%s: Failed to init RMA Bytes counter space\n", __func__); return rv; } return rv; } static uint32_t enterprise_rollback_create_counter(void) { /* * No need to increment the counter to initialize, this can be done later. */ return tlcl_define_space(ENT_ROLLBACK_COUNTER_INDEX, /*size=*/8, rw_counter_attributes, NULL, 0); } static uint32_t _factory_initialize_tpm(struct vb2_context *ctx) { RETURN_ON_FAILURE(tlcl_force_clear()); /* * Of all NVRAM spaces defined by this function the firmware space * must be defined last, because its existence is considered an * indication that TPM factory initialization was successfully * completed. */ RETURN_ON_FAILURE(setup_kernel_space(ctx)); /* * Define and set rec hash space, if available. No need to * create the RW hash space because we will definitely boot * once in normal mode before shipping, meaning that the space * will get created with correct permissions while still in * our hands. */ if (CONFIG(VBOOT_HAS_REC_HASH_SPACE)) RETURN_ON_FAILURE(set_mrc_hash_space(MRC_REC_HASH_NV_INDEX, mrc_hash_data)); /* Define and write firmware management parameters space. */ RETURN_ON_FAILURE(setup_fwmp_space(ctx)); /* * Define and write zero-touch enrollment (ZTE) spaces. For Cr50 devices, * these are set up elsewhere via TPM vendor commands. */ if (CONFIG(CHROMEOS) && (!(CONFIG(MAINBOARD_HAS_SPI_TPM_CR50) || CONFIG(MAINBOARD_HAS_I2C_TPM_CR50)))) RETURN_ON_FAILURE(setup_zte_spaces()); /* * On TPM 2.0, create a counter that survives TPM clear. This allows to * securely lock data during enterprise rollback by binding to this * counter's value. */ if (CONFIG(CHROMEOS)) RETURN_ON_FAILURE(enterprise_rollback_create_counter()); RETURN_ON_FAILURE(setup_firmware_space(ctx)); return TPM_SUCCESS; } uint32_t antirollback_lock_space_firmware(void) { return tlcl_lock_nv_write(FIRMWARE_NV_INDEX); } uint32_t antirollback_read_space_mrc_hash(uint32_t index, uint8_t *data, uint32_t size) { if (size != HASH_NV_SIZE) { VBDEBUG("TPM: Incorrect buffer size for hash idx 0x%x. " "(Expected=0x%x Actual=0x%x).\n", index, HASH_NV_SIZE, size); return TPM_E_READ_FAILURE; } return read_space_mrc_hash(index, data); } uint32_t antirollback_write_space_mrc_hash(uint32_t index, const uint8_t *data, uint32_t size) { uint8_t spc_data[HASH_NV_SIZE]; uint32_t rv; if (size != HASH_NV_SIZE) { VBDEBUG("TPM: Incorrect buffer size for hash idx 0x%x. " "(Expected=0x%x Actual=0x%x).\n", index, HASH_NV_SIZE, size); return TPM_E_WRITE_FAILURE; } rv = read_space_mrc_hash(index, spc_data); if (rv == TPM_E_BADINDEX) { /* * If space is not defined already for hash, define * new space. */ VBDEBUG("TPM: Initializing hash space.\n"); return set_mrc_hash_space(index, data); } if (rv != TPM_SUCCESS) return rv; return safe_write(index, data, size); } uint32_t antirollback_lock_space_mrc_hash(uint32_t index) { return tlcl_lock_nv_write(index); } #else /** * Like tlcl_write(), but checks for write errors due to hitting the 64-write * limit and clears the TPM when that happens. This can only happen when the * TPM is unowned, so it is OK to clear it (and we really have no choice). * This is not expected to happen frequently, but it could happen. */ static uint32_t safe_write(uint32_t index, const void *data, uint32_t length) { uint32_t result = tlcl_write(index, data, length); if (result == TPM_E_MAXNVWRITES) { RETURN_ON_FAILURE(tpm_clear_and_reenable()); return tlcl_write(index, data, length); } else { return result; } } /** * Similarly to safe_write(), this ensures we don't fail a DefineSpace because * we hit the TPM write limit. This is even less likely to happen than with * writes because we only define spaces once at initialization, but we'd * rather be paranoid about this. */ static uint32_t safe_define_space(uint32_t index, uint32_t perm, uint32_t size) { uint32_t result = tlcl_define_space(index, perm, size); if (result == TPM_E_MAXNVWRITES) { RETURN_ON_FAILURE(tpm_clear_and_reenable()); return tlcl_define_space(index, perm, size); } else { return result; } } static uint32_t _factory_initialize_tpm(struct vb2_context *ctx) { TPM_PERMANENT_FLAGS pflags; uint32_t result; vb2api_secdata_kernel_create_v0(ctx); result = tlcl_get_permanent_flags(&pflags); if (result != TPM_SUCCESS) return result; /* * TPM may come from the factory without physical presence finalized. * Fix if necessary. */ VBDEBUG("TPM: physicalPresenceLifetimeLock=%d\n", pflags.physicalPresenceLifetimeLock); if (!pflags.physicalPresenceLifetimeLock) { VBDEBUG("TPM: Finalizing physical presence\n"); RETURN_ON_FAILURE(tlcl_finalize_physical_presence()); } /* * The TPM will not enforce the NV authorization restrictions until the * execution of a TPM_NV_DefineSpace with the handle of * TPM_NV_INDEX_LOCK. Here we create that space if it doesn't already * exist. */ VBDEBUG("TPM: nvLocked=%d\n", pflags.nvLocked); if (!pflags.nvLocked) { VBDEBUG("TPM: Enabling NV locking\n"); RETURN_ON_FAILURE(tlcl_set_nv_locked()); } /* Clear TPM owner, in case the TPM is already owned for some reason. */ VBDEBUG("TPM: Clearing owner\n"); RETURN_ON_FAILURE(tpm_clear_and_reenable()); /* Define and write secdata_kernel space. */ RETURN_ON_FAILURE(safe_define_space(KERNEL_NV_INDEX, TPM_NV_PER_PPWRITE, VB2_SECDATA_KERNEL_SIZE_V02)); RETURN_ON_FAILURE(safe_write(KERNEL_NV_INDEX, ctx->secdata_kernel, VB2_SECDATA_KERNEL_SIZE_V02)); /* Define and write secdata_firmware space. */ RETURN_ON_FAILURE(safe_define_space(FIRMWARE_NV_INDEX, TPM_NV_PER_GLOBALLOCK | TPM_NV_PER_PPWRITE, VB2_SECDATA_FIRMWARE_SIZE)); RETURN_ON_FAILURE(safe_write(FIRMWARE_NV_INDEX, ctx->secdata_firmware, VB2_SECDATA_FIRMWARE_SIZE)); return TPM_SUCCESS; } uint32_t antirollback_lock_space_firmware(void) { return tlcl_set_global_lock(); } #endif /** * Perform one-time initializations. * * Create the NVRAM spaces, and set their initial values as needed. Sets the * nvLocked bit and ensures the physical presence command is enabled and * locked. */ static uint32_t factory_initialize_tpm(struct vb2_context *ctx) { uint32_t result; /* * Set initial values of secdata_firmware space. * kernel space is created in _factory_initialize_tpm(). */ vb2api_secdata_firmware_create(ctx); VBDEBUG("TPM: factory initialization\n"); /* * Do a full test. This only happens the first time the device is * turned on in the factory, so performance is not an issue. This is * almost certainly not necessary, but it gives us more confidence * about some code paths below that are difficult to * test---specifically the ones that set lifetime flags, and are only * executed once per physical TPM. */ result = tlcl_self_test_full(); if (result != TPM_SUCCESS) return result; result = _factory_initialize_tpm(ctx); if (result != TPM_SUCCESS) return result; /* _factory_initialize_tpm() writes initial secdata values to TPM immediately, so let vboot know that it's up to date now. */ ctx->flags &= ~(VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED | VB2_CONTEXT_SECDATA_KERNEL_CHANGED); VBDEBUG("TPM: factory initialization successful\n"); return TPM_SUCCESS; } uint32_t antirollback_read_space_firmware(struct vb2_context *ctx) { uint32_t rv; /* Read the firmware space. */ rv = read_space_firmware(ctx); if (rv == TPM_E_BADINDEX) { /* This seems the first time we've run. Initialize the TPM. */ VBDEBUG("TPM: Not initialized yet.\n"); RETURN_ON_FAILURE(factory_initialize_tpm(ctx)); } else if (rv != TPM_SUCCESS) { VBDEBUG("TPM: Firmware space in a bad state; giving up.\n"); return TPM_E_CORRUPTED_STATE; } return TPM_SUCCESS; } uint32_t antirollback_write_space_firmware(struct vb2_context *ctx) { if (CONFIG(CR50_IMMEDIATELY_COMMIT_FW_SECDATA)) tlcl_cr50_enable_nvcommits(); return safe_write(FIRMWARE_NV_INDEX, ctx->secdata_firmware, VB2_SECDATA_FIRMWARE_SIZE); } uint32_t antirollback_write_space_kernel(struct vb2_context *ctx) { /* Learn the expected size. */ uint8_t size = VB2_SECDATA_KERNEL_MIN_SIZE; vb2api_secdata_kernel_check(ctx, &size); /* * Ensure that the TPM actually commits our changes to NVMEN in case * there is a power loss or other unexpected event. The AP does not * write to the TPM during normal boot flow; it only writes during * recovery, software sync, or other special boot flows. When the AP * wants to write, it is imporant to actually commit changes. */ if (CONFIG(CR50_IMMEDIATELY_COMMIT_FW_SECDATA)) tlcl_cr50_enable_nvcommits(); return safe_write(KERNEL_NV_INDEX, ctx->secdata_kernel, size); } vb2_error_t vb2ex_tpm_clear_owner(struct vb2_context *ctx) { uint32_t rv; printk(BIOS_INFO, "Clearing TPM owner\n"); rv = tpm_clear_and_reenable(); if (rv) return VB2_ERROR_EX_TPM_CLEAR_OWNER; return VB2_SUCCESS; }