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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 <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79736
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Subrata Banik 2023-12-27 20:59:41 +05:30
parent acf10d6096
commit 0f90c5d5f9
4 changed files with 47 additions and 0 deletions
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5
src/security/tpm/tss/tcg-2.0/tss_marshaling.c
View File

@ -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",

5
src/security/tpm/tss/tcg-2.0/tss_structures.h
View File

@ -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;
};
};

28
src/security/tpm/tss/vendor/cr50/cr50.c vendored
View File

@ -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;
}

9
src/security/tpm/tss/vendor/cr50/cr50.h vendored
View File

@ -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_ */