tpm2_pcrreset(1)

1tpm2_pcrreset(1)            General Commands Manual           tpm2_pcrreset(1)
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NAME

6       tpm2_pcrreset(1) - Reset one or more PCR banks
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SYNOPSIS

9       tpm2_pcrreset [OPTIONS] PCR_INDEX ...
10

DESCRIPTION

12       tpm2_pcrreset(1)  -  Reset  PCR value in all banks for specified index.
13       More than one PCR index can be specified.
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15       The reset value is manufacturer-dependent and is either sequence of  00
16       or FF on the length of the hash algorithm for each supported bank.
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18       PCR_INDEX is a space separated list of PCR indexes to be reset when is‐
19       suing the command.
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OPTIONS

22       This tool accepts no tool specific options.
23
24       • --cphash=FILE
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26         File path to record the hash of the command parameters.  This is com‐
27         monly termed as cpHash.  NOTE: When this option is selected, The tool
28         will not actually execute the command, it simply returns a cpHash.
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COMMON OPTIONS

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

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

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

154   Reset a single PCR
155              tpm2_pcrreset 23
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157   Reset multiple PCRs
158              tpm2_pcrreset 16 23
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NOTES

161       On operating system’s locality (generally locality 0), only PCR 23  can
162       be  reset.  PCR-16 can also be reset on this locality, depending on TPM
163       manufacturers which could define this PCR as resettable.
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165       PCR 0 to 15 are not resettable (being part of SRTM).  PCR 16 to 22  are
166       mostly  reserved for DRTM or dedicated to specific localities and might
167       not be resettable depending on current TPM locality.
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Returns

170       Tools can return any of the following codes:
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172       • 0 - Success.
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174       • 1 - General non-specific error.
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176       • 2 - Options handling error.
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178       • 3 - Authentication error.
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180       • 4 - TCTI related error.
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182       • 5 - Non supported scheme.  Applicable to tpm2_testparams.
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BUGS

185       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
186

HELP

188       See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
189       fo/tpm2)
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193tpm2-tools                                                    tpm2_pcrreset(1)