csu3_am335x/EVSE/GPL/tpm2-tools-5.1/man/man1/tpm2_startauthsession.1

.\" Automatically generated by Pandoc 1.19.2.4
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.TH "tpm2_startauthsession" "1" "" "tpm2\-tools" "General Commands Manual"
.hy
.SH NAME
.PP
\f[B]tpm2_startauthsession\f[](1) \- Start a session with the TPM.
.SH SYNOPSIS
.PP
\f[B]tpm2_startauthsession\f[] [\f[I]OPTIONS\f[]]
.SH DESCRIPTION
.PP
\f[B]tpm2_startauthsession\f[](1) \- Starts a session with the TPM.
The default is to start a \f[I]trial\f[] session unless the \f[B]\-a\f[]
option is specified.
Saves the policy session data to a file.
This file can then be used in subsequent tools that can use a policy
file for authorization or policy events.
.PP
This will not work with resource managers (RMs) outside of
tpm2\-abrmd (https://%20github.com/tpm2-software/tpm2-abrmd), as most
RMs will flush session handles when a client disconnects from the IPC
channel.
.PP
This will work with direct TPM access, but note that internally this
calls a \f[I]ContextSave\f[] and a \f[I]ContextLoad\f[] on the session
handle, thus the session \f[B]cannot\f[] be saved/loaded again.
.SH OPTIONS
.IP \[bu] 2
\f[B]\-\-policy\-session\f[]:
.RS 2
.PP
Start a policy session of type \f[B]TPM_SE_POLICY\f[].
Default without this option is \f[B]TPM_SE_TRIAL\f[].
.PP
\f[B]NOTE\f[]: A \f[I]trial\f[] session is used when building a policy
and a \f[I]policy\f[] session is used when authenticating with a policy.
.RE
.IP \[bu] 2
\f[B]\-\-audit\-session\f[]:
.RS 2
.PP
Start an HMAC session to be used as an audit session.
Default without this option is \f[B]TPM2_SE_TRIAL\f[].
.RE
.IP \[bu] 2
\f[B]\-\-hmac\-session\f[]:
.RS 2
.PP
Start an HMAC session of type \f[B]TPM_SE_HMAC\f[].
Default without this option is \f[B]TPM2_SE_TRIAL\f[].
.RE
.IP \[bu] 2
\f[B]\-g\f[], \f[B]\-\-hash\-algorithm\f[]=\f[I]ALGORITHM\f[]:
.RS 2
.PP
The hash algorithm used in computation of the policy digest.
.RE
.IP \[bu] 2
\f[B]\-c\f[], \f[B]\-\-key\-context\f[]=\f[I]OBJECT\f[]:
.RS 2
.PP
Set the tpmkey and bind objects to be the same.
Session parameter encryption is turned on.
Session parameter decryption is turned on.
Parameter encryption/decryption symmetric\-key set to AES\-CFB.
.RE
.IP \[bu] 2
\f[B]\-S\f[], \f[B]\-\-session\f[]=\f[I]FILE\f[]:
.RS 2
.PP
The name of the policy session file, required.
.RE
.IP \[bu] 2
\f[B]\-\-bind\-context\f[]=\f[I]FILE\f[]:
.RS 2
.PP
Set the bind object.
Session parameter encryption is off.
Use \f[B]tpm2_sessionconfig\f[] to turn on.
Session parameter decryption is off.
Use \f[B]tpm2_sessionconfig\f[] to turn on.
Parameter encryption/decryption symmetric\-key set to AES\-CFB.
.RE
.IP \[bu] 2
\f[B]\-\-bind\-auth\f[]=\f[I]AUTH\f[]:
.RS 2
.PP
Set the authorization value for the bind object.
.RE
.IP \[bu] 2
\f[B]\-\-tpmkey\-context\f[]=\f[I]FILE\f[]:
.RS 2
.PP
Set the tpmkey object.
Session parameter encryption is off.
Use \f[B]tpm2_sessionconfig\f[] to turn on.
Session parameter decryption is off.
Use \f[B]tpm2_sessionconfig\f[] to turn on.
Parameter encryption/decryption symmetric\-key set to AES\-CFB.
.RE
.SS References
.SH Context Object Format
.PP
The type of a context object, whether it is a handle or file name, is
determined according to the following logic \f[I]in\-order\f[]:
.IP \[bu] 2
If the argument is a file path, then the file is loaded as a restored
TPM transient object.
.IP \[bu] 2
If the argument is a \f[I]prefix\f[] match on one of:
.RS 2
.IP \[bu] 2
owner: the owner hierarchy
.IP \[bu] 2
platform: the platform hierarchy
.IP \[bu] 2
endorsement: the endorsement hierarchy
.IP \[bu] 2
lockout: the lockout control persistent object
.RE
.IP \[bu] 2
If the argument argument can be loaded as a number it will be treat as a
handle, e.g.
0x81010013 and used directly.\f[I]OBJECT\f[].
.SH Authorization Formatting
.PP
Authorization for use of an object in TPM2.0 can come in 3 different
forms: 1.
Password 2.
HMAC 3.
Sessions
.PP
\f[B]NOTE:\f[] "Authorizations default to the \f[B]EMPTY PASSWORD\f[]
when not specified".
.SS Passwords
.PP
Passwords are interpreted in the following forms below using prefix
identifiers.
.PP
\f[B]Note\f[]: By default passwords are assumed to be in the string form
when they do not have a prefix.
.SS String
.PP
A string password, specified by prefix "str:" or it\[aq]s absence (raw
string without prefix) is not interpreted, and is directly used for
authorization.
.SS Examples
.IP
.nf
\f[C]
foobar
str:foobar
\f[]
.fi
.SS Hex\-string
.PP
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.
.SS Example
.IP
.nf
\f[C]
hex:0x1122334455667788
\f[]
.fi
.SS File
.PP
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.
.SS Examples
.IP
.nf
\f[C]
#\ 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
\f[]
.fi
.SS Sessions
.PP
When using a policy session to authorize the use of an object, prefix
the option argument with the \f[I]session\f[] 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 \f[B]Passwords\f[] section.
.SS Examples
.PP
To use a session context file called \f[I]session.ctx\f[].
.IP
.nf
\f[C]
session:session.ctx
\f[]
.fi
.PP
To use a session context file called \f[I]session.ctx\f[] \f[B]AND\f[]
send the authvalue mypassword.
.IP
.nf
\f[C]
session:session.ctx+mypassword
\f[]
.fi
.PP
To use a session context file called \f[I]session.ctx\f[] \f[B]AND\f[]
send the \f[I]HEX\f[] authvalue 0x11223344.
.IP
.nf
\f[C]
session:session.ctx+hex:11223344
\f[]
.fi
.SS PCR Authorizations
.PP
You can satisfy a PCR policy using the "pcr:" prefix and the PCR
minilanguage.
The PCR minilanguage is as follows:
\f[C]<pcr\-spec>=<raw\-pcr\-file>\f[]
.PP
The PCR spec is documented in in the section "PCR bank specifiers".
.PP
The \f[C]raw\-pcr\-file\f[] is an \f[B]optional\f[] the output of the
raw PCR contents as returned by \f[I]tpm2_pcrread(1)\f[].
.PP
PCR bank specifiers (common/pcr.md)
.SS Examples
.PP
To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifier
of:
.IP
.nf
\f[C]
pcr:sha256:0,1,2,3
\f[]
.fi
.PP
specifying \f[I]AUTH\f[].
.SH COMMON OPTIONS
.PP
This collection of options are common to many programs and provide
information that many users may expect.
.IP \[bu] 2
\f[B]\-h\f[], \f[B]\-\-help=[man|no\-man]\f[]: 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.
.RS 2
.PP
To successfully use the manpages feature requires the manpages to be
installed or on \f[I]MANPATH\f[], See man(1) for more details.
.RE
.IP \[bu] 2
\f[B]\-v\f[], \f[B]\-\-version\f[]: Display version information for this
tool, supported tctis and exit.
.IP \[bu] 2
\f[B]\-V\f[], \f[B]\-\-verbose\f[]: Increase the information that the
tool prints to the console during its execution.
When using this option the file and line number are printed.
.IP \[bu] 2
\f[B]\-Q\f[], \f[B]\-\-quiet\f[]: Silence normal tool output to stdout.
.IP \[bu] 2
\f[B]\-Z\f[], \f[B]\-\-enable\-errata\f[]: 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.
.SH TCTI Configuration
.PP
The TCTI or "Transmission Interface" is the communication mechanism with
the TPM.
TCTIs can be changed for communication with TPMs across different
mediums.
.PP
To control the TCTI, the tools respect:
.IP "1." 3
The command line option \f[B]\-T\f[] or \f[B]\-\-tcti\f[]
.IP "2." 3
The environment variable: \f[I]TPM2TOOLS_TCTI\f[].
.PP
\f[B]Note:\f[] The command line option always overrides the environment
variable.
.PP
The current known TCTIs are:
.IP \[bu] 2
tabrmd \- The resource manager, called
tabrmd (https://github.com/tpm2-software/tpm2-abrmd).
Note that tabrmd and abrmd as a tcti name are synonymous.
.IP \[bu] 2
mssim \- Typically used for communicating to the TPM software simulator.
.IP \[bu] 2
device \- Used when talking directly to a TPM device file.
.IP \[bu] 2
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 \f[I]ANY\f[] options and \f[I]MUST BE\f[] presented as
the exact text of "none".
.PP
The arguments to either the command line option or the environment
variable are in the form:
.PP
\f[C]<tcti\-name>:<tcti\-option\-config>\f[]
.PP
Specifying an empty string for either the \f[C]<tcti\-name>\f[] or
\f[C]<tcti\-option\-config>\f[] results in the default being used for
that portion respectively.
.SS TCTI Defaults
.PP
When a TCTI is not specified, the default TCTI is searched for using
\f[I]dlopen(3)\f[] semantics.
The tools will search for \f[I]tabrmd\f[], \f[I]device\f[] and
\f[I]mssim\f[] TCTIs \f[B]IN THAT ORDER\f[] and \f[B]USE THE FIRST ONE
FOUND\f[].
You can query what TCTI will be chosen as the default by using the
\f[B]\-v\f[] option to print the version information.
The "default\-tcti" key\-value pair will indicate which of the
aforementioned TCTIs is the default.
.SS Custom TCTIs
.PP
Any TCTI that implements the dynamic TCTI interface can be loaded.
The tools internally use \f[I]dlopen(3)\f[], and the raw
\f[I]tcti\-name\f[] value is used for the lookup.
Thus, this could be a path to the shared library, or a library name as
understood by \f[I]dlopen(3)\f[] semantics.
.SH TCTI OPTIONS
.PP
This collection of options are used to configure the various known TCTI
modules available:
.IP \[bu] 2
\f[B]device\f[]: For the device TCTI, the TPM character device file for
use by the device TCTI can be specified.
The default is \f[I]/dev/tpm0\f[].
.RS 2
.PP
Example: \f[B]\-T device:/dev/tpm0\f[] or \f[B]export
\f[I]TPM2TOOLS_TCTI\f[]="device:/dev/tpm0"\f[]
.RE
.IP \[bu] 2
\f[B]mssim\f[]: 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.
.RS 2
.PP
Example: \f[B]\-T mssim:host=localhost,port=2321\f[] or \f[B]export
\f[I]TPM2TOOLS_TCTI\f[]="mssim:host=localhost,port=2321"\f[]
.RE
.IP \[bu] 2
\f[B]abrmd\f[]: For the abrmd TCTI, the configuration string format is a
series of simple key value pairs separated by a \[aq],\[aq] character.
Each key and value string are separated by a \[aq]=\[aq] character.
.RS 2
.IP \[bu] 2
TCTI abrmd supports two keys:
.RS 2
.IP "1." 3
\[aq]bus_name\[aq] : The name of the tabrmd service on the bus (a
string).
.IP "2." 3
\[aq]bus_type\[aq] : The type of the dbus instance (a string) limited to
\[aq]session\[aq] and \[aq]system\[aq].
.RE
.PP
Specify the tabrmd tcti name and a config string of
\f[C]bus_name=com.example.FooBar\f[]:
.PP
\f[C]\\\-\-tcti=tabrmd:bus_name=com.example.FooBar\f[]
.PP
Specify the default (abrmd) tcti and a config string of
\f[C]bus_type=session\f[]:
.PP
\f[C]\\\-\-tcti:bus_type=session\f[]
.PP
\f[B]NOTE\f[]: abrmd and tabrmd are synonymous.
the various known TCTI modules.
# EXAMPLES
.RE
.SS Start a \f[I]trial\f[] session and save the session data to a file
.IP
.nf
\f[C]
tpm2_startauthsession\ \-S\ mysession.ctx
\f[]
.fi
.SS Start a \f[I]policy\f[] session and save the session data to a file
.IP
.nf
\f[C]
tpm2_startauthsession\ \-\-policy\-session\ \-S\ mysession.ctx
\f[]
.fi
.SS Start an encrypted and bound \f[I]policy\f[] session and save the
session data to a file
.IP
.nf
\f[C]
tpm2_createprimary\ \-c\ primary.ctx
tpm2_startauthsession\ \-\-policy\-session\ \-c\ primary.ctx\ \-S\ mysession.ctx
\f[]
.fi
.SH Returns
.PP
Tools can return any of the following codes:
.IP \[bu] 2
0 \- Success.
.IP \[bu] 2
1 \- General non\-specific error.
.IP \[bu] 2
2 \- Options handling error.
.IP \[bu] 2
3 \- Authentication error.
.IP \[bu] 2
4 \- TCTI related error.
.IP \[bu] 2
5 \- Non supported scheme.
Applicable to tpm2_testparams.
.SH BUGS
.PP
Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
.SH HELP
.PP
See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)