1tpm2_readclock(1)           General Commands Manual          tpm2_readclock(1)
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NAME

6       tpm2_readclock(1) - Retrieves the time information from the TPM.
7

SYNOPSIS

9       tpm2_readclock [OPTIONS]
10

DESCRIPTION

12       tpm2_readclock(1)  -Reads the current TPMS_TIME_INFO structure from the
13       TPM.  The structure contains the current setting of Time, Clock, reset‐
14       Count,  and  restartCount.   The structure is output as YAML to stdout.
15       The YAML output is defined as:
16
17              time: 13673142     # 64 bit value of time TPM has been powered on in ms.
18              clock_info:
19                clock: 13673142  # 64 bit value of time TPM has been powered on since last TPM2_Clear in ms.
20                reset_count: 0   # 32 bit value of the number of TPM Resets since the last
21                                 # TPM2_Clear.
22                restart_count: 0 # 32 bit value of the number of times that TPM2_Shutdown or
23                                 # _TPM_Hash_Start have occurred since the last TPM Reset or
24                                 # TPM2_Clear.
25                safe: yes        # boolean yes|no value that no value of Clock greater than
26                                 # the current value of Clock has been previously reported by
27                                 # the TPM.
28
29       This tool takes no arguments and no tool specific options.
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31   References

COMMON OPTIONS

33       This collection of options are common to many programs and provide  in‐
34       formation that many users may expect.
35
36       • -h,  --help=[man|no-man]:  Display the tools manpage.  By default, it
37         attempts to invoke the manpager for the  tool,  however,  on  failure
38         will  output  a short tool summary.  This is the same behavior if the
39         “man” option argument is specified, however if explicit “man” is  re‐
40         quested,  the  tool  will  provide errors from man on stderr.  If the
41         “no-man” option if specified, or the manpager fails,  the  short  op‐
42         tions will be output to stdout.
43
44         To  successfully use the manpages feature requires the manpages to be
45         installed or on MANPATH, See man(1) for more details.
46
47       • -v, --version: Display version information for this  tool,  supported
48         tctis and exit.
49
50       • -V,  --verbose:  Increase the information that the tool prints to the
51         console during its execution.  When using this option  the  file  and
52         line number are printed.
53
54       • -Q, --quiet: Silence normal tool output to stdout.
55
56       • -Z, --enable-errata: Enable the application of errata fixups.  Useful
57         if an errata fixup needs to be applied to commands sent to  the  TPM.
58         Defining  the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.  in‐
59         formation many users may expect.
60

TCTI Configuration

62       The TCTI or “Transmission Interface”  is  the  communication  mechanism
63       with  the TPM.  TCTIs can be changed for communication with TPMs across
64       different mediums.
65
66       To control the TCTI, the tools respect:
67
68       1. The command line option -T or --tcti
69
70       2. The environment variable: TPM2TOOLS_TCTI.
71
72       Note: The command line option always overrides  the  environment  vari‐
73       able.
74
75       The current known TCTIs are:
76
77       • tabrmd      -     The     resource     manager,     called     tabrmd
78         (https://github.com/tpm2-software/tpm2-abrmd).  Note that tabrmd  and
79         abrmd as a tcti name are synonymous.
80
81       • mssim  - Typically used for communicating to the TPM software simula‐
82         tor.
83
84       • device - Used when talking directly to a TPM device file.
85
86       • none - Do not initalize a connection with the TPM.  Some tools  allow
87         for off-tpm options and thus support not using a TCTI.  Tools that do
88         not support it will error when attempted to be used  without  a  TCTI
89         connection.   Does  not  support ANY options and MUST BE presented as
90         the exact text of “none”.
91
92       The arguments to either the command  line  option  or  the  environment
93       variable are in the form:
94
95       <tcti-name>:<tcti-option-config>
96
97       Specifying  an  empty  string  for  either the <tcti-name> or <tcti-op‐
98       tion-config> results in the default being used for that portion respec‐
99       tively.
100
101   TCTI Defaults
102       When  a  TCTI  is not specified, the default TCTI is searched for using
103       dlopen(3) semantics.  The tools will  search  for  tabrmd,  device  and
104       mssim  TCTIs  IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query
105       what TCTI will be chosen as the default by using the -v option to print
106       the  version information.  The “default-tcti” key-value pair will indi‐
107       cate which of the aforementioned TCTIs is the default.
108
109   Custom TCTIs
110       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
111       tools internally use dlopen(3), and the raw tcti-name value is used for
112       the lookup.  Thus, this could be a path to the shared library, or a li‐
113       brary name as understood by dlopen(3) semantics.
114

TCTI OPTIONS

116       This collection of options are used to configure the various known TCTI
117       modules available:
118
119       • device: For the device TCTI, the TPM character device file for use by
120         the device TCTI can be specified.  The default is /dev/tpm0.
121
122         Example:    -T   device:/dev/tpm0   or   export   TPM2TOOLS_TCTI=“de‐
123         vice:/dev/tpm0”
124
125       • mssim: For the mssim TCTI, the domain name or  IP  address  and  port
126         number  used  by  the  simulator  can  be specified.  The default are
127         127.0.0.1 and 2321.
128
129         Example: -T mssim:host=localhost,port=2321  or  export  TPM2TOOLS_TC‐
130         TI=“mssim:host=localhost,port=2321”
131
132       • abrmd:  For  the abrmd TCTI, the configuration string format is a se‐
133         ries of simple key value pairs separated by a  `,'  character.   Each
134         key and value string are separated by a `=' character.
135
136         • TCTI abrmd supports two keys:
137
138           1. `bus_name'  :  The  name  of  the  tabrmd  service on the bus (a
139              string).
140
141           2. `bus_type' : The type of the dbus instance (a string) limited to
142              `session' and `system'.
143
144         Specify  the tabrmd tcti name and a config string of bus_name=com.ex‐
145         ample.FooBar:
146
147                \--tcti=tabrmd:bus_name=com.example.FooBar
148
149         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
150         sion:
151
152                \--tcti:bus_type=session
153
154         NOTE:  abrmd  and tabrmd are synonymous.  the various known TCTI mod‐
155         ules.
156

EXAMPLES

158   Read the clock
159              tpm2_readclock
160              time: 13673142
161              clock_info:
162                clock: 13673142
163                reset_count: 0
164                restart_count: 0
165                safe: yes
166

Returns

168       Tools can return any of the following codes:
169
170       • 0 - Success.
171
172       • 1 - General non-specific error.
173
174       • 2 - Options handling error.
175
176       • 3 - Authentication error.
177
178       • 4 - TCTI related error.
179
180       • 5 - Non supported scheme.  Applicable to tpm2_testparams.
181

BUGS

183       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
184

HELP

186       See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
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190tpm2-tools                                                   tpm2_readclock(1)