NAME

       tpm2_getcap(1) - Display TPM capabilities in a human readable form.

SYNOPSIS

       tpm2_getcap [OPTIONS] [CAPABILITY]

DESCRIPTION

       tpm2_getcap(1)  -  Query  the  TPM  for it’s capabilities / properties and print them to the console.  It
       takes a string form of the capability to query as an argument to the tool.  Currently supported capabili‐
       ty groups are:

       • algorithms: Display data about supported algorithms.

       • commands: Display data about supported commands.

       • pcrs: Display currently allocated PCRs.

       • properties-fixed: Display fixed TPM properties.

       • properties-variable: Display variable TPM properties.

       • ecc-curves: Display data about elliptic curves.

       • handles-transient: Display handles about transient objects.

       • handles-persistent: Display handles about persistent objects.

       • handles-permanent: Display handles about permanent objects.

       • handles-pcr: Display handles about PCRs.

       • handles-nv-index: Display handles about NV Indices.

       • handles-loaded-session: Display handles about both loaded HMAC and policy sessions.

       • handles-saved-session: Display handles about saved sessions.

       • vendor[:num]: Displays the vendor properties as a hex buffer output.  The string “vendor” can  be  suf‐
         fixed  with a colon followed by a number as understood by strtoul(3) with a 0 base.  That value is used
         as the property value within the
       TPM2_GetCapability command, and defaults to 1.  An example to call it with a  property  value  of  2  is:
       tpm2_getcap vendor:2

         NOTE: if vendor requests hang, try the “-i” option to ignore the moreData field and only read once.

OPTIONS

       • -l, --list:

         List  known  supported capability names.  These names can be supplied as the argument to the -c option.
         Output is in a YAML compliant list to stdout.

         For example:

                  - algorithms
                  - commands
                  - properties-fixed
                  ...

       • --ignore-moredata

       Ignores the moreData field when dealing with buggy TPM responses.

COMMON OPTIONS

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

       • -h, --help=[man|no-man]: Display the tools manpage.  By default, it attempts to invoke the manpager for
         the tool, however, on failure will output a short tool summary.  This is the same behavior if the “man”
         option argument is specified, however if explicit “man” is requested, the tool will provide errors from
         man  on  stderr.  If the “no-man” option if specified, or the manpager fails, the short options will be
         output to stdout.

         To successfully use the manpages feature requires the manpages to  be  installed  or  on  MANPATH,  See
         man(1) for more details.

       • -v, --version: Display version information for this tool, supported tctis and exit.

       • -V, --verbose: Increase the information that the tool prints to the console during its execution.  When
         using this option the file and line number are printed.

       • -Q, --quiet: Silence normal tool output to stdout.

       • -Z,  --enable-errata:  Enable  the application of errata fixups.  Useful if an errata fixup needs to be
         applied to commands sent to the TPM.  Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.

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:

       • tabrmd  - The resource manager, called tabrmd (https://github.com/tpm2-software/tpm2-abrmd).  Note that
         tabrmd and abrmd as a tcti name are synonymous.

       • mssim - Typically used for communicating to the TPM software simulator.

       • device - Used when talking directly to a TPM device file.

       • none - Do not initalize a connection with the TPM.  Some tools allow for off-tpm options and thus  sup‐
         port not using a TCTI.  Tools that do not support it will error when attempted to be used without a TC‐
         TI connection.  Does not support ANY options and MUST BE presented as the exact text of “none”.

       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 be‐
       ing 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 “de‐
       fault-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:

       • device: For the device TCTI, the TPM character device file for use by the device TCTI can be specified.
         The default is /dev/tpm0.

         Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“device:/dev/tpm0”

       • mssim:  For  the mssim TCTI, the domain name or IP address and port number used by the simulator can be
         specified.  The default are 127.0.0.1 and 2321.

         Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TCTI=“mssim:host=localhost,port=2321”

       • abrmd: For the abrmd TCTI, the configuration string format is a series of simple key value pairs  sepa‐
         rated by a `,' character.  Each key and value string are separated by a `=' character.

         • TCTI abrmd supports two keys:

           1. `bus_name' : The name of the tabrmd service on the bus (a string).

           2. `bus_type' : The type of the dbus instance (a string) limited to `session' and `system'.

         Specify the tabrmd tcti name and a config string of bus_name=com.example.FooBar:

                \--tcti=tabrmd:bus_name=com.example.FooBar

         Specify the default (abrmd) tcti and a config string of bus_type=session:

                \--tcti:bus_type=session

         NOTE: abrmd and tabrmd are synonymous.

EXAMPLES

   To list the fixed properties of the TPM
              tpm2_getcap properties-fixed

   To list the supported capability groups
              tpm2_getcap -l

Returns

       Tools can return any of the following codes:

       • 0 - Success.

       • 1 - General non-specific error.

       • 2 - Options handling error.

       • 3 - Authentication error.

       • 4 - TCTI related error.

       • 5 - Non supported scheme.  Applicable to tpm2_testparams.

BUGS

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

HELP

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

tpm2-tools                                                                                        tpm2_getcap(1)