From 0f90c5d5f9faa31b53da6680175da19f9d8efbfa Mon Sep 17 00:00:00 2001 From: Subrata Banik Date: Wed, 27 Dec 2023 20:59:41 +0530 Subject: [PATCH] security/tpm: Retrieve factory configuration for device w/ Google TPM This patch enables retrieval of factory configuration data from Google TPM devices (both Cr50 and Ti50). This patch utilizes vendor-specific command TPM2_CR50_SUB_CMD_GET_FACTORY_CONFIG (68). The factory config space is a 64-bit, one-time programmable. For the unprovisioned one, the read will be 0x0. BUG=b:317880956 TEST=Able to retrieve the factory config from google/screebo. Change-Id: Ifd0e850770152a03aa46d7f8bbb76f7520a59081 Signed-off-by: Subrata Banik Reviewed-on: https://review.coreboot.org/c/coreboot/+/79736 Reviewed-by: Kapil Porwal Tested-by: build bot (Jenkins) --- src/security/tpm/tss/tcg-2.0/tss_marshaling.c | 5 ++++ src/security/tpm/tss/tcg-2.0/tss_structures.h | 5 ++++ src/security/tpm/tss/vendor/cr50/cr50.c | 28 +++++++++++++++++++ src/security/tpm/tss/vendor/cr50/cr50.h | 9 ++++++ 4 files changed, 47 insertions(+) diff --git a/src/security/tpm/tss/tcg-2.0/tss_marshaling.c b/src/security/tpm/tss/tcg-2.0/tss_marshaling.c index f1b9522e6c..5ade6395bb 100644 --- a/src/security/tpm/tss/tcg-2.0/tss_marshaling.c +++ b/src/security/tpm/tss/tcg-2.0/tss_marshaling.c @@ -348,6 +348,9 @@ static int marshal_cr50_vendor_command(struct obuf *ob, const void *command_body case TPM2_CR50_SUB_CMD_RESET_EC: rc |= obuf_write_be16(ob, *sub_command); break; + case TPM2_CR50_SUB_CMD_GET_FACTORY_CONFIG: + rc |= obuf_write_be16(ob, *sub_command); + break; default: /* Unsupported subcommand. */ printk(BIOS_WARNING, "Unsupported cr50 subcommand: 0x%04x\n", @@ -581,6 +584,8 @@ static int unmarshal_vendor_command(struct ibuf *ib, return ibuf_read_be8(ib, &vcr->boot_mode); case TPM2_CR50_SUB_CMD_RESET_EC: break; + case TPM2_CR50_SUB_CMD_GET_FACTORY_CONFIG: + return ibuf_read_be64(ib, &vcr->factory_config); default: printk(BIOS_ERR, "%s:%d - unsupported vendor command %#04x!\n", diff --git a/src/security/tpm/tss/tcg-2.0/tss_structures.h b/src/security/tpm/tss/tcg-2.0/tss_structures.h index a73f4c48e6..f2682b1878 100644 --- a/src/security/tpm/tss/tcg-2.0/tss_structures.h +++ b/src/security/tpm/tss/tcg-2.0/tss_structures.h @@ -352,6 +352,11 @@ struct vendor_command_response { uint8_t recovery_button_state; uint8_t tpm_mode; uint8_t boot_mode; + /* + * bits 63..8 : reserved + * bits 7..0 : factory config + */ + uint64_t factory_config; }; }; diff --git a/src/security/tpm/tss/vendor/cr50/cr50.c b/src/security/tpm/tss/vendor/cr50/cr50.c index 87889d128b..31eab2d5d4 100644 --- a/src/security/tpm/tss/vendor/cr50/cr50.c +++ b/src/security/tpm/tss/vendor/cr50/cr50.c @@ -176,3 +176,31 @@ tpm_result_t tlcl_cr50_reset_ec(void) return TPM_SUCCESS; } + +tpm_result_t tlcl_cr50_get_factory_config(uint64_t *factory_config) +{ + struct tpm2_response *response; + uint16_t factory_config_command = TPM2_CR50_SUB_CMD_GET_FACTORY_CONFIG; + *factory_config = 0; + + response = tpm_process_command(TPM2_CR50_VENDOR_COMMAND, &factory_config_command); + + if (!response) + return TPM_IOERROR; + + /* Explicitly inform caller when command is not supported */ + if (response->hdr.tpm_code == VENDOR_RC_NO_SUCH_COMMAND || + response->hdr.tpm_code == VENDOR_RC_NO_SUCH_SUBCOMMAND) + return TPM_CB_NO_SUCH_COMMAND; + + /* Unexpected return code from TPM */ + if (response->hdr.tpm_code) + return TPM_IOERROR; + + /* TPM command completed without error */ + *factory_config = response->vcr.factory_config; + + printk(BIOS_INFO, "Reading factory config = %016" PRIX64 "\n", *factory_config); + + return TPM_SUCCESS; +} diff --git a/src/security/tpm/tss/vendor/cr50/cr50.h b/src/security/tpm/tss/vendor/cr50/cr50.h index edd5083d17..f7e5c68332 100644 --- a/src/security/tpm/tss/vendor/cr50/cr50.h +++ b/src/security/tpm/tss/vendor/cr50/cr50.h @@ -17,6 +17,7 @@ #define TPM2_CR50_SUB_CMD_TPM_MODE (40) #define TPM2_CR50_SUB_CMD_GET_BOOT_MODE (52) #define TPM2_CR50_SUB_CMD_RESET_EC (53) +#define TPM2_CR50_SUB_CMD_GET_FACTORY_CONFIG (68) /* Cr50 vendor-specific error codes. */ #define VENDOR_RC_ERR 0x00000500 @@ -105,4 +106,12 @@ tpm_result_t tlcl_cr50_immediate_reset(uint16_t timeout_ms); */ tpm_result_t tlcl_cr50_reset_ec(void); +/** + * TPM command to get the factory config. + * + * Returns TPM_* for errors. + * On Success, TPM_SUCCESS if factory config is successfully retrieved. + */ +tpm_result_t tlcl_cr50_get_factory_config(uint64_t *factory_config); + #endif /* CR50_TSS_STRUCTURES_H_ */