table of contents
| tpm2_policyor(1) | General Commands Manual | tpm2_policyor(1) |
NAME¶
tpm2_policyor(1) - 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¶
- •
- -L, --policy=FILE:
File to save the compounded policy digest.
- •
- -l, --policy-list=POLICY_FILE_LIST:
The list of files for the policy digests that has to be compounded resulting in individual policies being added to final policy digest that can authenticate the object. The list begins with the policy digest hash alg.
- •
- -S, --session=FILE:
The policy session file generated via the -S option to tpm2_startauthsession(1).
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. 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:
- 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 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:
- 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. the various known TCTI modules.
EXAMPLES¶
Creates two sets of PCR data files, one of them being the existing PCR values and other being a set of PCR values that would result if the PCR were extended with a known value. Now create two separate policy digests, each with one set of the PCR values using tpm2_policypcr(1) tool in trial sessions. Now build a policy_or with the two PCR policy digests as inputs. Create a sealing object with an authentication policy compounding the 2 policies with tpm2_policyor and seal a secret. Unsealing with either of the PCR sets should be successful.
Create two unique pcr policies with corresponding unique sets of¶
pcrs.
Start with pcr value 0¶
-
tpm2_pcrreset 23
PCR1 policy¶
-
tpm2_startauthsession -S session.ctx tpm2_policypcr -S session.ctx -l sha1:23 -L set1.pcr0.policy tpm2_flushcontext session.ctx rm session.ctx
PCR2 policy¶
-
tpm2_pcrextend 23:sha1=f1d2d2f924e986ac86fdf7b36c94bcdf32beec15 tpm2_startauthsession -S session.ctx tpm2_policypcr -S session.ctx -l sha1:23 -L set2.pcr0.policy tpm2_flushcontext session.ctx rm session.ctx
Create a policyOR resulting from compounding the two unique pcr¶
policies in an OR fashion
-
tpm2_startauthsession -S session.ctx tpm2_policyor -S session.ctx -L policyOR \ -l sha256:set1.pcr0.policy,set2.pcr0.policy tpm2_flushcontext session.ctx rm session.ctx
Create a sealing object with auth policyOR created above.¶
-
tpm2_createprimary -C o -c prim.ctx tpm2_create -g sha256 -u sealkey.pub -r sealkey.priv -L policyOR -C prim.ctx \ -i- <<< "secretpass" tpm2_load -C prim.ctx -c sealkey.ctx -u sealkey.pub -r sealkey.priv
Attempt unsealing by satisfying the policyOR by satisfying SECOND of¶
the two policies.
-
tpm2_startauthsession -S session.ctx --policy-session tpm2_policypcr -S session.ctx -l sha1:23 tpm2_policyor -S session.ctx -L policyOR \ -l sha256:set1.pcr0.policy,set2.pcr0.policy unsealed=`tpm2_unseal -p session:session.ctx -c sealkey.ctx` echo $unsealed tpm2_flushcontext session.ctx rm session.ctx
Extend the pcr to emulate tampering of the system software and hence¶
the pcr value.
-
tpm2_pcrextend 23:sha1=f1d2d2f924e986ac86fdf7b36c94bcdf32beec15
Attempt unsealing by trying to satisy the policOR by attempting to¶
satisy one of the two policies.
-
tpm2_startauthsession -S session.ctx --policy-session tpm2_policypcr -S session.ctx -l sha1:23
This should fail¶
-
tpm2_policyor -S session.ctx -L policyOR \ -l sha256:set1.pcr0.policy,set2.pcr0.policy tpm2_flushcontext session.ctx rm session.ctx
Reset pcr to get back to the first set of pcr value¶
-
tpm2_pcrreset 23
Attempt unsealing by satisfying the policyOR by satisfying FIRST of¶
the two policies.
-
tpm2_startauthsession -S session.ctx --policy-session tpm2_policypcr -S session.ctx -l sha1:23 tpm2_policyor -S session.ctx -L policyOR \ -l sha256:set1.pcr0.policy,set2.pcr0.policy unsealed=`tpm2_unseal -p session:session.ctx -c sealkey.ctx` echo $unsealed tpm2_flushcontext session.ctx rm session.ctx
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.01.org/mailman/listinfo/tpm2)
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