Ubuntu Manpage: tpm2_evictcontrol(1) - Make a transient object persistent or evict a persistent object.

NAME

       tpm2_evictcontrol(1) - Make a transient object persistent or evict a persistent object.

SYNOPSIS

       tpm2_evictcontrol [OPTIONS] [ARGUMENT]

DESCRIPTION

       tpm2_evictcontrol(1)  -  Allows  a  transient object to be made persistent or a persistent
       object to be evicted.  The HANDLE argument controls the index the handle will be  assigned
       to.  If the object specified via -c is transient, and a permanent HANDLE is specified, the
       object will be persisted at HANDLE.  If HANDLE is a -, then the object will  be  persisted
       at  the  first  available  permanent handle location.  If the object specified via -c is a
       permanent handle, then the object will be evicted from it’s permenent handle location.

OPTIONS

• -C, --hierarchy=OBJECT:

The authorization hierarchy used to authorize the commands. Defaults to the “owner”
hierarchy. Supported options are:

• o for TPM_RH_OWNER

• p for TPM_RH_PLATFORM

• <num> where a raw number can be used.

• -c, --object-context=OBJECT:

A context object specifier of a transient or persistent object. If OBJECT is a
transient object it will be persisted, either to the handle specified by the argument or
to first available vacant persistent handle. If the OBJECT is for a persistent object,
then the object will be evicted from non-volatile memory.

• -P, --auth=AUTH:

The authorization value for the hierarchy specified with -C.

• -o, --output=FILE:

Optionally output a serialized object representing the persistent handle. If
untampered, these files are safer to use then raw persistent handles. A raw persistent
handle should be verified that the object it points to is as expected.

• --cphash=FILE

File path to record the hash of the command parameters. This is commonly termed as
cpHash. NOTE: When this option is selected, The tool will not actually execute the
command, it simply returns a cpHash.

• ARGUMENT the command line argument specifies the persistent handle to save the transient
object to.

Output

       The  tool  outputs a YAML compliant dictionary with the fields: persistent-handle: action:
       evicted|persisted

       Where persistent-handle is the handle the action occurred to.  Where action can either  be
       one  of  evicted  or  persisted.   If  an  object  is evicted then the object is no longer
       resident at the persistent-handle address within the TPM.  If an object is persisted  then
       the object is resident at the persistent-handle address within the TPM.

   References

Context Object Format

       The type of a context object, whether it is a handle or file name, is determined according
       to the following logic in-order:

       • If the argument is a file path, then the file is loaded  as  a  restored  TPM  transient
         object.

       • If the argument is a prefix match on one of:

         • owner: the owner hierarchy

         • platform: the platform hierarchy

         • endorsement: the endorsement hierarchy

         • lockout: the lockout control persistent object

       • If  the  argument  argument  can  be  loaded  as  a number it will be treat as a handle,
         e.g. 0x81010013 and used directly._OBJECT_.

Authorization Formatting

Authorization for use of an object in TPM2.0 can come in 3 different forms: 1. Password
2. HMAC 3. Sessions

NOTE: “Authorizations default to the EMPTY PASSWORD when not specified”.

Passwords
Passwords are interpreted in the following forms below using prefix identifiers.

Note: By default passwords are assumed to be in the string form when they do not have a
prefix.

String
A string password, specified by prefix “str:” or it’s absence (raw string without prefix)
is not interpreted, and is directly used for authorization.

Examples
foobar
str:foobar

Hex-string
A hex-string password, specified by prefix “hex:” is converted from a hexidecimal form
into a byte array form, thus allowing passwords with non-printable and/or terminal un-
friendly characters.

Example
hex:1122334455667788

File
A file based password, specified be prefix “file:” should be the path of a file containing
the password to be read by the tool or a “-” to use stdin. Storing passwords in files
prevents information leakage, passwords passed as options can be read from the process
list or common shell history features.

Examples
# to use stdin and be prompted
file:-

# to use a file from a path
file:path/to/password/file

# to echo a password via stdin:
echo foobar | tpm2_tool -p file:-

# to use a bash here-string via stdin:

tpm2_tool -p file:- <<< foobar

Sessions
When using a policy session to authorize the use of an object, prefix the option argument
with the session keyword. Then indicate a path to a session file that was created with
tpm2_startauthsession(1). Optionally, if the session requires an auth value to be sent
with the session handle (eg policy password), then append a + and a string as described in
the Passwords section.

Examples
To use a session context file called session.ctx.

session:session.ctx

To use a session context file called session.ctx AND send the authvalue mypassword.

session:session.ctx+mypassword

To use a session context file called session.ctx AND send the HEX authvalue 0x11223344.

session:session.ctx+hex:11223344

PCR Authorizations
You can satisfy a PCR policy using the “pcr:” prefix and the PCR minilanguage. The PCR
minilanguage is as follows: <pcr-spec>=<raw-pcr-file>

The PCR spec is documented in in the section “PCR bank specifiers”.

The raw-pcr-file is an optional argument that contains the output of the raw PCR contents
as returned by tpm2_pcrread(1).

PCR bank specifiers

Examples
To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifier of:

pcr:sha256:0,1,2,3

specifying AUTH.

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

   To make a transient handle persistent at address 0x81010002
              tpm2_changeauth -c o ownerauth
              tpm2_createprimary -c primary.ctx -P ownerauth
              tpm2_evictcontrol -C o -c primary.ctx 0x81010002 -P ownerauth

   To evict a persistent handle
              tpm2_evictcontrol -C o -c 0x81010002 -P ownerauth

   To make a transient handle persistent and output a serialized persistent handle.
              tpm2_evictcontrol -C o -c primary.ctx -o primary.handle -P ownerauth

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)