1tpm2_clear(1)               General Commands Manual              tpm2_clear(1)
2
3
4

NAME

6       tpm2_clear(1)  - Clears lockout, endorsement and owner hierarchy autho‐
7       rization values.
8

SYNOPSIS

10       tpm2_clear [OPTIONS] [ARGUMENT]
11

DESCRIPTION

13       tpm2_clear(1) - Send a clear command to the TPM to clear the 3  hierar‐
14       chy  authorization values.  As an argument takes the auth value for ei‐
15       ther platform or lockout hierarchy
16
17       NOTE: All objects created under the respective hierarchies are lost.
18

OPTIONS

20-c, --auth-hierarchy=OBJECT:
21
22         Specifies the hierarchy the tools should operate on.  By  default  it
23         operates on the lockout hierarchy.
24
25         NOTE  :  Operating on platform hierarchy require platform authentica‐
26         tion.
27
28--cphash=FILE
29
30         File path to record the hash of the command parameters.  This is com‐
31         monly termed as cpHash.  NOTE: When this option is selected, The tool
32         will not actually execute the command, it simply returns a cpHash.
33
34ARGUMENT the command line argument specifies the AUTH to be  set  for
35         the object specified with -c.
36
37   References

Context Object Format

39       The  type  of a context object, whether it is a handle or file name, is
40       determined according to the following logic in-order:
41
42       • If the argument is a file path, then the file is loaded as a restored
43         TPM transient object.
44
45       • If the argument is a prefix match on one of:
46
47         • owner: the owner hierarchy
48
49         • platform: the platform hierarchy
50
51         • endorsement: the endorsement hierarchy
52
53         • lockout: the lockout control persistent object
54
55       • If  the  argument argument can be loaded as a number it will be treat
56         as a handle, e.g. 0x81010013 and used directly._OBJECT_.
57

Authorization Formatting

59       Authorization for use of an object in TPM2.0 can come  in  3  different
60       forms: 1.  Password 2.  HMAC 3.  Sessions
61
62       NOTE:  “Authorizations  default  to  the EMPTY PASSWORD when not speci‐
63       fied”.
64
65   Passwords
66       Passwords are interpreted in the following  forms  below  using  prefix
67       identifiers.
68
69       Note:  By  default  passwords are assumed to be in the string form when
70       they do not have a prefix.
71
72   String
73       A string password, specified by prefix  “str:”  or  it’s  absence  (raw
74       string without prefix) is not interpreted, and is directly used for au‐
75       thorization.
76
77   Examples
78              foobar
79              str:foobar
80
81   Hex-string
82       A hex-string password, specified by prefix “hex:” is converted  from  a
83       hexidecimal  form  into a byte array form, thus allowing passwords with
84       non-printable and/or terminal un-friendly characters.
85
86   Example
87              hex:1122334455667788
88
89   File
90       A file based password, specified be prefix “file:” should be  the  path
91       of  a  file  containing the password to be read by the tool or a “-” to
92       use stdin.  Storing passwords in files  prevents  information  leakage,
93       passwords passed as options can be read from the process list or common
94       shell history features.
95
96   Examples
97              # to use stdin and be prompted
98              file:-
99
100              # to use a file from a path
101              file:path/to/password/file
102
103              # to echo a password via stdin:
104              echo foobar | tpm2_tool -p file:-
105
106              # to use a bash here-string via stdin:
107
108              tpm2_tool -p file:- <<< foobar
109
110   Sessions
111       When using a policy session to authorize the use of an  object,  prefix
112       the  option argument with the session keyword.  Then indicate a path to
113       a session file that was created with tpm2_startauthsession(1).  Option‐
114       ally, if the session requires an auth value to be sent with the session
115       handle (eg policy password), then append a + and a string as  described
116       in the Passwords section.
117
118   Examples
119       To use a session context file called session.ctx.
120
121              session:session.ctx
122
123       To use a session context file called session.ctx AND send the authvalue
124       mypassword.
125
126              session:session.ctx+mypassword
127
128       To use a session context file called session.ctx AND send the HEX auth‐
129       value 0x11223344.
130
131              session:session.ctx+hex:11223344
132
133   PCR Authorizations
134       You  can satisfy a PCR policy using the “pcr:” prefix and the PCR mini‐
135       language.      The     PCR     minilanguage     is     as      follows:
136       <pcr-spec>=<raw-pcr-file>
137
138       The PCR spec is documented in in the section “PCR bank specifiers”.
139
140       The  raw-pcr-file  is  an optional argument that contains the output of
141       the raw PCR contents as returned by tpm2_pcrread(1).
142
143       PCR bank specifiers (pcr.md)
144
145   Examples
146       To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
147       er of:
148
149              pcr:sha256:0,1,2,3
150
151       specifying AUTH.
152

COMMON OPTIONS

154       This  collection of options are common to many programs and provide in‐
155       formation that many users may expect.
156
157-h, --help=[man|no-man]: Display the tools manpage.  By  default,  it
158         attempts  to  invoke  the  manpager for the tool, however, on failure
159         will output a short tool summary.  This is the same behavior  if  the
160         “man”  option argument is specified, however if explicit “man” is re‐
161         quested, the tool will provide errors from man  on  stderr.   If  the
162         “no-man”  option  if  specified, or the manpager fails, the short op‐
163         tions will be output to stdout.
164
165         To successfully use the manpages feature requires the manpages to  be
166         installed or on MANPATH, See man(1) for more details.
167
168-v,  --version:  Display version information for this tool, supported
169         tctis and exit.
170
171-V, --verbose: Increase the information that the tool prints  to  the
172         console  during  its  execution.  When using this option the file and
173         line number are printed.
174
175-Q, --quiet: Silence normal tool output to stdout.
176
177-Z, --enable-errata: Enable the application of errata fixups.  Useful
178         if  an  errata fixup needs to be applied to commands sent to the TPM.
179         Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.   in‐
180         formation many users may expect.
181

TCTI Configuration

183       The  TCTI  or  “Transmission  Interface” is the communication mechanism
184       with the TPM.  TCTIs can be changed for communication with TPMs  across
185       different mediums.
186
187       To control the TCTI, the tools respect:
188
189       1. The command line option -T or --tcti
190
191       2. The environment variable: TPM2TOOLS_TCTI.
192
193       Note:  The  command  line option always overrides the environment vari‐
194       able.
195
196       The current known TCTIs are:
197
198       • tabrmd     -     The     resource     manager,     called      tabrmd
199         (https://github.com/tpm2-software/tpm2-abrmd).   Note that tabrmd and
200         abrmd as a tcti name are synonymous.
201
202       • mssim - Typically used for communicating to the TPM software  simula‐
203         tor.
204
205       • device - Used when talking directly to a TPM device file.
206
207       • none  - Do not initalize a connection with the TPM.  Some tools allow
208         for off-tpm options and thus support not using a TCTI.  Tools that do
209         not  support  it  will error when attempted to be used without a TCTI
210         connection.  Does not support ANY options and MUST  BE  presented  as
211         the exact text of “none”.
212
213       The  arguments  to  either  the  command line option or the environment
214       variable are in the form:
215
216       <tcti-name>:<tcti-option-config>
217
218       Specifying an empty string for  either  the  <tcti-name>  or  <tcti-op‐
219       tion-config> results in the default being used for that portion respec‐
220       tively.
221
222   TCTI Defaults
223       When a TCTI is not specified, the default TCTI is  searched  for  using
224       dlopen(3)  semantics.   The  tools  will  search for tabrmd, device and
225       mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND.  You  can  query
226       what TCTI will be chosen as the default by using the -v option to print
227       the version information.  The “default-tcti” key-value pair will  indi‐
228       cate which of the aforementioned TCTIs is the default.
229
230   Custom TCTIs
231       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
232       tools internally use dlopen(3), and the raw tcti-name value is used for
233       the lookup.  Thus, this could be a path to the shared library, or a li‐
234       brary name as understood by dlopen(3) semantics.
235

TCTI OPTIONS

237       This collection of options are used to configure the various known TCTI
238       modules available:
239
240device: For the device TCTI, the TPM character device file for use by
241         the device TCTI can be specified.  The default is /dev/tpm0.
242
243         Example:   -T   device:/dev/tpm0   or   export    TPM2TOOLS_TCTI=“de‐
244         vice:/dev/tpm0”
245
246mssim:  For  the  mssim  TCTI, the domain name or IP address and port
247         number used by the simulator  can  be  specified.   The  default  are
248         127.0.0.1 and 2321.
249
250         Example:  -T  mssim:host=localhost,port=2321  or export TPM2TOOLS_TC‐
251         TI=“mssim:host=localhost,port=2321”
252
253abrmd: For the abrmd TCTI, the configuration string format is  a  se‐
254         ries  of  simple  key value pairs separated by a `,' character.  Each
255         key and value string are separated by a `=' character.
256
257         • TCTI abrmd supports two keys:
258
259           1. `bus_name' : The name of  the  tabrmd  service  on  the  bus  (a
260              string).
261
262           2. `bus_type' : The type of the dbus instance (a string) limited to
263              `session' and `system'.
264
265         Specify the tabrmd tcti name and a config string of  bus_name=com.ex‐
266         ample.FooBar:
267
268                \--tcti=tabrmd:bus_name=com.example.FooBar
269
270         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
271         sion:
272
273                \--tcti:bus_type=session
274
275         NOTE: abrmd and tabrmd are synonymous.  the various known  TCTI  mod‐
276         ules.
277

EXAMPLES

279   Set owner, endorsement and lockout authorizations to an empty value
280              tpm2_clear lockoutpasswd
281
282   Clear the authorization values on the platform hierarchy
283              tpm2_clear -c p
284

Returns

286       Tools can return any of the following codes:
287
288       • 0 - Success.
289
290       • 1 - General non-specific error.
291
292       • 2 - Options handling error.
293
294       • 3 - Authentication error.
295
296       • 4 - TCTI related error.
297
298       • 5 - Non supported scheme.  Applicable to tpm2_testparams.
299

BUGS

301       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
302

HELP

304       See the Mailing List (https://lists.linuxfoundation.org/mailman/listin
305       fo/tpm2)
306
307
308
309tpm2-tools                                                       tpm2_clear(1)
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