man
1 tpm2_getcap
tpm2_getcap(1) General Commands Manual tpm2_getcap(1)
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 capability
groups are:
o algorithms: Display data about supported algorithms.
o commands: Display data about supported commands.
o pcrs: Display currently allocated PCRs.
o properties-fixed: Display fixed TPM properties.
o properties-variable: Display variable TPM properties.
o ecc-curves: Display data about elliptic curves.
o handles-transient: Display handles about transient objects.
o handles-persistent: Display handles about persistent objects.
o handles-permanent: Display handles about permanent objects.
o handles-pcr: Display handles about PCRs.
o handles-nv-index: Display handles about NV Indices.
o handles-loaded-session: Display handles about both loaded HMAC and
policy sessions.
o handles-saved-session: Display handles about saved sessions.
OPTIONS
o -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
...
COMMON OPTIONS
This collection of options are common to many programs and provide in-
formation that many users may expect.
o -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 re-
quested, the tool will provide errors from man on stderr. If the
"no-man" option if specified, or the manpager fails, the short op-
tions 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.
o -v, --version: Display version information for this tool, supported
tctis and exit.
o -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.
o -Q, --quiet: Silence normal tool output to stdout.
o -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 vari-
able.
The current known TCTIs are:
o tabrmd - The resource manager, called tabrmd
(https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
abrmd as a tcti name are synonymous.
o mssim - Typically used for communicating to the TPM software simula-
tor.
o device - Used when talking directly to a TPM device file.
o none - Do not initalize a connection with the TPM. Some tools allow
for off-tpm options and thus support not using a TCTI. Tools that do
not support it will error when attempted to be used without a TCTI
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-op-
tion-config> results in the default being used for that portion respec-
tively.
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 indi-
cate 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 li-
brary name as understood by dlopen(3) semantics.
TCTI OPTIONS
This collection of options are used to configure the various known TCTI
modules available:
o 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="de-
vice:/dev/tpm0"
o 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_TC-
TI="mssim:host=localhost,port=2321"
o abrmd: For the abrmd TCTI, the configuration string format is a se-
ries of simple key value pairs separated by a `,' character. Each
key and value string are separated by a `=' character.
o 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.ex-
ample.FooBar:
\--tcti=tabrmd:bus_name=com.example.FooBar
Specify the default (abrmd) tcti and a config string of bus_type=ses-
sion:
\--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:
o 0 - Success.
o 1 - General non-specific error.
o 2 - Options handling error.
o 3 - Authentication error.
o 4 - TCTI related error.
o 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.01.org/mailman/listinfo/tpm2)
tpm2-tools tpm2_getcap(1)