tpm2_policyor - Man Page

logically OR's two policies together.

Synopsis

tpm2_policyor [Options]

Description

tpm2_policyor(1) - Generates a policy_or event with the TPM. It expects a session to be already established via tpm2_startauthsession(1). If the input session is a trial session this tool generates a policy digest that compounds two or more input policy digests such that the resulting policy digest requires at least one of the policy events being true. If the input session is real policy session tpm2_policyor(1) authenticates the object successfully if at least one of the policy events are true.

Options

References

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

Create an authorization policy for a sealing object that compounds a pcr policy and a policypassword in an OR fashion and show satisfying either policies could unseal the secret.

Create policypcr as first truth value for compounding the policies

tpm2_startauthsession -S session.ctx
tpm2_policypcr -S session.ctx -L policy.pcr -l sha256:0,1,2,3
tpm2_flushcontext session.ctx

Create policypassword as second truth value for compounding the

policies

tpm2_startauthsession -S session.ctx
tpm2_policypassword -S session.ctx -L policy.pass
tpm2_flushcontext session.ctx

Compound the two policies in an OR fashion with tpm2_policyor

command

tpm2_startauthsession -S session.ctx
tpm2_policyor -S session.ctx -L policy.or sha256:policy.pass,policy.pcr
tpm2_flushcontext session.ctx

Create a sealing object and attach the auth policy from

tpm2_policyor command

tpm2_createprimary -c prim.ctx -Q
echo "secret" | tpm2_create -C prim.ctx -c key.ctx -u key.pub -r key.priv \
-L policy.or -i-

Satisfy auth policy using password and unseal the secret

tpm2_startauthsession -S session.ctx --policy-session
tpm2_policypassword -S session.ctx
tpm2_policyor -S session.ctx sha256:policy.pass,policy.pcr
tpm2_unseal -c key.ctx -p session:session.ctx
tpm2_flushcontext session.ctx

Satisfy auth policy using pcr and unseal the secret

tpm2_startauthsession -S session.ctx --policy-session
tpm2_policypcr -S session.ctx -l sha256:0,1,2,3
tpm2_policyor -S session.ctx sha256:policy.pass,policy.pcr
tpm2_unseal -c key.ctx -p session:session.ctx
tpm2_flushcontext session.ctx

Returns

Tools can return any of the following codes:

Limitations

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.

Bugs

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

Help

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

Referenced By

tpm2_policypcr(1).

tpm2-tools General Commands Manual