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tpm2_policylocality - Man Page

Restrict TPM object authorization to specific localities.


tpm2_policylocality [Options] [ARGUMENT]


tpm2_policylocality(1) - Restricts TPM object authorization to specific TPM locality. Useful when you want to allow only specific locality with the TPM object. A locality indicates the source of the command, for example it could be from the application layer or the driver layer, each would have it’s own locality integer. Localities are hints to the TPM and are enforced by the software communicating to the TPM. Thus they are not trusted inputs on their own and are implemented in platform specific ways.

As an argument it takes the LOCALITY as an integer or friendly name.

Localities are fixed to a byte in size and have two representations, locality and extended locality.

Localities 0 through 4 are the normal locality representation and are represented as set bit indexes. Thus locality 0 is indicated by 1<<0 and locality 4 is indicated by 1<<4. Rather then using raw numbers, these localities can also be specified by the friendly names of: - zero: locality 0 or 1<<0 - one: locality 1 or 1<<1 - two: locality 2 or 1<<2 - three: locality 3 or 1<<3 - four: locality 4 or 1<<4

Anything from the range 32 - 255 are extended localities.



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:


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:


Start a policy session and extend it with a specific locality number (like 3). Attempts to perform other operations would fail.

Create an policy restricted by locality 3

tpm2_startauthsession -S session.dat

tpm2_policylocality -S session.dat -L policy.dat three

tpm2_flushcontext session.dat

Create the object with auth policy

tpm2_createprimary -C o -c prim.ctx

tpm2_create -C prim.ctx -u sealkey.pub -r sealkey.priv -L policy.dat \

Try unseal operation

tpm2_load -C prim.ctx -u sealkey.pub -r sealkey.priv -n sealkey.name \
-c sealkey.ctx

tpm2_startauthsession \--policy-session -S session.dat

tpm2_policylocality -S session.dat -L policy.dat three

# Change to locality 3, Note: this operation varies on different platforms

tpm2_unseal -p session:session.dat -c sealkey.ctx

tpm2_flushcontext session.dat


Tools can return any of the following codes:


It expects a session to be already established via tpm2_startauthsession(1) and requires one of the following:

Without it, most resource managers will not save session state between command invocations.


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


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


tpm2-tools General Commands Manual