NAME¶

TPMLIB_GetTPMProperty - Get a runtime property of the TPM

LIBRARY¶

TPM library (libtpms, -ltpms)

SYNOPSIS¶

#include <libtpms/tpm_library.h>

TPM_RESULT TPMLIB_GetTPMProperty(enum TPMLIB_TPMProperty, int *result);

DESCRIPTION¶

The TPMLIB_GetTPMProperty() call is used to retrieve run-time parameters of the TPM such as the number of authorization sessions it can hold or the maximum sizes of the permanent state, savestate or volatile state blobs.

This function can be called before or after the TPM has been created. The current implementation of libtpms will return the same value before and after the TPM was started.

With the introduction of the function TPMLIB_ChooseTPMVersion(), the call to this function should be executed after the TPM version has been chosen. The reason is that different TPM versions may return different values.

The following properties have been defined:

TPMPROP_TPM_RSA_KEY_LENGTH_MAX

The maximum size of an RSA key.

TPMPROP_TPM_BUFFER_MAX

The maximum sizes of the TPM command and result buffers.

TPMPROP_TPM_KEY_HANDLES

The number of key slots.

TPMPROP_TPM_OWNER_EVICT_KEY_HANDLES

The number of owner-evict keys.

TPMPROP_TPM_MIN_AUTH_SESSIONS

The number of authorization sessions.

TPMPROP_TPM_MIN_TRANS_SESSIONS

The number of transport sessions.

TPMPROP_TPM_MIN_DAA_SESSIONS

The number of DAA sessions.

TPMPROP_TPM_MIN_SESSION_LIST

The size of the session list.

TPMPROP_TPM_MIN_COUNTERS

The number of monotonic counters.

TPMPROP_TPM_NUM_FAMILY_TABLE_ENTRY_MIN

The number of family entries.

TPMPROP_TPM_NUM_DELEGATE_TABLE_ENTRY_MIN

The number of delegate entries.

TPMPROP_TPM_SPACE_SAFETY_MARGIN

The space safety margin used for the worst-case sizes of the savestate and volatile state blobs. This safety margin is not used for the size of the permanent data blob.

TPMPROP_TPM_MAX_NV_SPACE

The maximum size of the permanent data blob.

TPMPROP_TPM_MAX_SAVESTATE_SPACE

The maximum size of the savestate blob (includes the space safety margin).

TPMPROP_TPM_MAX_VOLATILESTATE_SPACE

The maximum size of the volatile state blob (includes the space saferty margin).

ERRORS¶

TPM_SUCCESS

The function completed successfully.

TPM_FAIL

An undefined property was queried.

For a complete list of TPM error codes please consult the include file libtpms/tpm_error.h

EXAMPLE¶

 #include <stdio.h>
 #include <libtpms/tpm_library.h>
 #include <libtpms/tpm_error.h>
 int main(void) {
     TPM_RESULT res;
     int result;
     int rc = 0;
     if (TPMLIB_MainInit() != TPM_SUCCESS) {
         fprintf(stderr, "Could not start the TPM.\n");
         return 1;
     }
     if (TPMLIB_GetTPMProperty(TPMPROP_TPM_RSA_KEY_LENGTH_MAX, &result)
         != TPM_SUCCESS) {
         fprintf(stderr, "Could not read the max. size of RSA keys.\n");
         goto err_exit;
     }
     fprintf(stdout, "Max. size of RSA keys: %d\n", result);
 err_exit:
     TPMLIB_Terminate();
     return 0;
 }

SEE ALSO¶

TPMLIB_MainInit(3), TPMLIB_Terminate(3), TPMLIB_Process(3), TPMLIB_RegisterCallbacks(3), TPMLIB_GetVersion(3), TPMLIB_ChooseTPMVersion(3)