tpm2_flushcontext man page

tpm2_flushcontext(1) — Remove a specified handle, or all contexts associated with a transient object, loaded session or saved session from the TPM.

Synopsis

tpm2_flushcontext [Options] [ARGUMENT]

Description

tpm2_flushcontext(1) - Remove a specified handle, or all contexts associated with a transient object, loaded session or saved session from the TPM. The object to be flushed is specified as the first argument to the tool and is in one of the following forms: - The handle of the object to be flushed from the TPM. Must be a valid handle number. - Flush a session via a session file. A session file is generated from tpm2_startauthsession(1)'s -S option.

Options

Common Options

This collection of options are common to many programs and provide information that many users may expect.

TCTI Configuration

The TCTI or "Transmission Interface" is the communication mechanism with the TPM. TCTIs can be changed for communication with TPMs across different mediums.

To control the TCTI, the tools respect:

  1. The command line option -T or --tcti
  2. The environment variable: TPM2TOOLS_TCTI.

Note: The command line option always overrides the environment variable.

The current known TCTIs are:

The arguments to either the command line option or the environment variable are in the form:

<tcti-name>:<tcti-option-config>

Specifying an empty string for either the <tcti-name> or <tcti-option-config> results in the default being used for that portion respectively.

TCTI Defaults

When a TCTI is not specified, the default TCTI is searched for using dlopen(3) semantics. The tools will search for tabrmd, device and mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query what TCTI will be chosen as the default by using the -v option to print the version information. The "default-tcti" key-value pair will indicate which of the aforementioned TCTIs is the default.

Custom TCTIs

Any TCTI that implements the dynamic TCTI interface can be loaded. The tools internally use dlopen(3), and the raw tcti-name value is used for the lookup. Thus, this could be a path to the shared library, or a library name as understood by dlopen(3) semantics.

Tcti Options

This collection of options are used to configure the various known TCTI modules available:

Examples

Flushing a Transient Object

Typically, when using the TPM, the interactions occur through a resource manager, like tpm2-abrmd(8). When the process exits, transient object handles are flushed. Thus, flushing transient objects through the command line is not required. However, when interacting with the TPM directly, this scenario is possible. The below example assumes direct TPM access not brokered by a resource manager. Specifically we will use the simulator.

tpm2_createprimary -Tmssim -c primary.ctx

tpm2_getcap -T mssim handles-transient
- 0x80000000

tpm2_flushcontext -T mssim 0x80000000

Flush All the Transient Objects

tpm2_flushcontext \--transient-object

Flush a Session

tpm2_startauthsession -S session.dat

tpm2_flushcontext session.dat

Returns

Tools can return any of the following codes:

Bugs

Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)

Help

See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)

Info

tpm2-tools General Commands Manual