tpm2_policyduplicationselect - Man Page
Restricts duplication to a specific new parent.
Synopsis
tpm2_policyduplicationselect [Options]
Description
tpm2_policyduplicationselect(1) - Restricts duplication to a specific new parent.
Options
-S, --session=FILE:
The policy session file generated via the -S option to tpm2_startauthsession(1).
-n, --object-name=FILE:
Input name file of the object to be duplicated.
-N, --parent-name=FILE:
Input name file of the new parent.
-L, --policy=FILE:
File to save the policy digest.
--include-object:
If exists, the object name will be included in the value in policy digest.
References
Common Options
This collection of options are common to many programs and provide information that many users may expect.
-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.
- -R, --autoflush: Enable autoflush for transient objects created by the command. If a parent object is loaded from a context file also the transient parent object will be flushed. Autoflush can also be activated if the environment variable TPM2TOOLS_AUTOFLUSH is is set to yes or true. information 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:
- The command line option -T or --tcti
- 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 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-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:
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 separated by a `,' character. Each key and value string are separated by a `=' character.
TCTI abrmd supports two keys:
- `bus_name' : The name of the tabrmd service on the bus (a string).
- `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. the various known TCTI modules.
Examples
Setup a duplication role policy to restricted new parent
Create source parent and destination(or new) parent
tpm2_createprimary -C n -g sha256 -G rsa -c dst_n.ctx -Q tpm2_createprimary -C o -g sha256 -G rsa -c src_o.ctx -Q
Create the restricted parent policy
tpm2_readpublic -c dst_n.ctx -n dst_n.name -Q tpm2_startauthsession -S session.ctx tpm2_policyduplicationselect -S session.ctx -N dst_n.name \ -L policydupselect.dat -Q tpm2_flushcontext session.ctx rm session.ctx
Create the object to be duplicated using the policy
tpm2_create -C src_o.ctx -g sha256 -G rsa -r dupkey.priv -u dupkey.pub \ -L policydupselect.dat -a "sensitivedataorigin|sign|decrypt" -c dupkey.ctx -Q tpm2_readpublic -c dupkey.ctx -n dupkey.name -Q
Satisfy the policy and duplicate the object
tpm2_startauthsession -S session.ctx --policy-session tpm2_policyduplicationselect -S session.ctx -N dst_n.name -n dupkey.name -Q tpm2_duplicate -C dst_n.ctx -c dupkey.ctx -G null -p session:session.ctx \ -r new_dupkey.priv -s dupseed.dat tpm2_flushcontext session.ctx rm session.ctx
Notes
- This command usually cooperates with tpm2_duplicate(1), so referring to the man page of tpm2_duplicate(1) is recommended.
- This command will set the policy session’s command code to TPM_CC_Duplicate which enables duplication role of the policy.
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.
Limitations
It expects a session to be already established via tpm2_startauthsession(1) and requires one of the following:
- direct device access
- extended session support with tpm2-abrmd.
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.linuxfoundation.org/mailman/listinfo/tpm2)