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       · ARGUMENT the command line argument specifies the AUTH to be  set  for
29         the object specified with -c.
30
31   References

Context Object Format

33       The  type  of a context object, whether it is a handle or file name, is
34       determined according to the following logic in-order:
35
36       · If the argument is a file path, then the file is loaded as a restored
37         TPM transient object.
38
39       · If the argument is a prefix match on one of:
40
41         · owner: the owner hierarchy
42
43         · platform: the platform hierarchy
44
45         · endorsement: the endorsement hierarchy
46
47         · lockout: the lockout control persistent object
48
49       · If  the  argument argument can be loaded as a number it will be treat
50         as a handle, e.g.  0x81010013 and used directly.OBJECT.
51

Authorization Formatting

53       Authorization for use of an object in TPM2.0 can come  in  3  different
54       forms: 1.  Password 2.  HMAC 3.  Sessions
55
56       NOTE:  "Authorizations  default  to  the EMPTY PASSWORD when not speci‐
57       fied".
58
59   Passwords
60       Passwords are interpreted in the following  forms  below  using  prefix
61       identifiers.
62
63       Note:  By  default  passwords are assumed to be in the string form when
64       they do not have a prefix.
65
66   String
67       A string password, specified by prefix  "str:"  or  it's  absence  (raw
68       string without prefix) is not interpreted, and is directly used for au‐
69       thorization.
70
71   Examples
72              foobar
73              str:foobar
74
75   Hex-string
76       A hex-string password, specified by prefix "hex:" is converted  from  a
77       hexidecimal  form  into a byte array form, thus allowing passwords with
78       non-printable and/or terminal un-friendly characters.
79
80   Example
81              hex:0x1122334455667788
82
83   File
84       A file based password, specified be prefix "file:" should be  the  path
85       of  a  file  containing the password to be read by the tool or a "-" to
86       use stdin.  Storing passwords in files  prevents  information  leakage,
87       passwords passed as options can be read from the process list or common
88       shell history features.
89
90   Examples
91              # to use stdin and be prompted
92              file:-
93
94              # to use a file from a path
95              file:path/to/password/file
96
97              # to echo a password via stdin:
98              echo foobar | tpm2_tool -p file:-
99
100              # to use a bash here-string via stdin:
101
102              tpm2_tool -p file:- <<< foobar
103
104   Sessions
105       When using a policy session to authorize the use of an  object,  prefix
106       the  option argument with the session keyword.  Then indicate a path to
107       a session file that was created with tpm2_startauthsession(1).  Option‐
108       ally, if the session requires an auth value to be sent with the session
109       handle (eg policy password), then append a + and a string as  described
110       in the Passwords section.
111
112   Examples
113       To use a session context file called session.ctx.
114
115              session:session.ctx
116
117       To use a session context file called session.ctx AND send the authvalue
118       mypassword.
119
120              session:session.ctx+mypassword
121
122       To use a session context file called session.ctx AND send the HEX auth‐
123       value 0x11223344.
124
125              session:session.ctx+hex:11223344
126
127   PCR Authorizations
128       You  can satisfy a PCR policy using the "pcr:" prefix and the PCR mini‐
129       language.      The     PCR     minilanguage     is     as      follows:
130       <pcr-spec>=<raw-pcr-file>
131
132       The PCR spec is documented in in the section "PCR bank specifiers".
133
134       The  raw-pcr-file  is an optional the output of the raw PCR contents as
135       returned by tpm2_pcrread(1).
136
137       PCR bank specifiers (common/pcr.md)
138
139   Examples
140       To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
141       er of:
142
143              pcr:sha256:0,1,2,3
144
145       specifying AUTH.
146

COMMON OPTIONS

148       This  collection of options are common to many programs and provide in‐
149       formation that many users may expect.
150
151       · -h, --help=[man|no-man]: Display the tools manpage.  By  default,  it
152         attempts  to  invoke  the  manpager for the tool, however, on failure
153         will output a short tool summary.  This is the same behavior  if  the
154         "man"  option argument is specified, however if explicit "man" is re‐
155         quested, the tool will provide errors from man  on  stderr.   If  the
156         "no-man"  option  if  specified, or the manpager fails, the short op‐
157         tions will be output to stdout.
158
159         To successfully use the manpages feature requires the manpages to  be
160         installed or on MANPATH, See man(1) for more details.
161
162       · -v,  --version:  Display version information for this tool, supported
163         tctis and exit.
164
165       · -V, --verbose: Increase the information that the tool prints  to  the
166         console  during  its  execution.  When using this option the file and
167         line number are printed.
168
169       · -Q, --quiet: Silence normal tool output to stdout.
170
171       · -Z, --enable-errata: Enable the application of errata fixups.  Useful
172         if  an  errata fixup needs to be applied to commands sent to the TPM.
173         Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.   in‐
174         formation many users may expect.
175

TCTI Configuration

177       The  TCTI  or  "Transmission  Interface" is the communication mechanism
178       with the TPM.  TCTIs can be changed for communication with TPMs  across
179       different mediums.
180
181       To control the TCTI, the tools respect:
182
183       1. The command line option -T or --tcti
184
185       2. The environment variable: TPM2TOOLS_TCTI.
186
187       Note:  The  command  line option always overrides the environment vari‐
188       able.
189
190       The current known TCTIs are:
191
192       · tabrmd     -     The     resource     manager,     called      tabrmd
193         (https://github.com/tpm2-software/tpm2-abrmd).   Note that tabrmd and
194         abrmd as a tcti name are synonymous.
195
196       · mssim - Typically used for communicating to the TPM software  simula‐
197         tor.
198
199       · device - Used when talking directly to a TPM device file.
200
201       · none  - Do not initalize a connection with the TPM.  Some tools allow
202         for off-tpm options and thus support not using a TCTI.  Tools that do
203         not  support  it  will error when attempted to be used without a TCTI
204         connection.  Does not support ANY options and MUST  BE  presented  as
205         the exact text of "none".
206
207       The  arguments  to  either  the  command line option or the environment
208       variable are in the form:
209
210       <tcti-name>:<tcti-option-config>
211
212       Specifying an empty string for  either  the  <tcti-name>  or  <tcti-op‐
213       tion-config> results in the default being used for that portion respec‐
214       tively.
215
216   TCTI Defaults
217       When a TCTI is not specified, the default TCTI is  searched  for  using
218       dlopen(3)  semantics.   The  tools  will  search for tabrmd, device and
219       mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND.  You  can  query
220       what TCTI will be chosen as the default by using the -v option to print
221       the version information.  The "default-tcti" key-value pair will  indi‐
222       cate which of the aforementioned TCTIs is the default.
223
224   Custom TCTIs
225       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
226       tools internally use dlopen(3), and the raw tcti-name value is used for
227       the lookup.  Thus, this could be a path to the shared library, or a li‐
228       brary name as understood by dlopen(3) semantics.
229

TCTI OPTIONS

231       This collection of options are used to configure the various known TCTI
232       modules available:
233
234       · device: For the device TCTI, the TPM character device file for use by
235         the device TCTI can be specified.  The default is /dev/tpm0.
236
237         Example:   -T   device:/dev/tpm0   or   export    TPM2TOOLS_TCTI="de‐
238         vice:/dev/tpm0"
239
240       · mssim:  For  the  mssim  TCTI, the domain name or IP address and port
241         number used by the simulator  can  be  specified.   The  default  are
242         127.0.0.1 and 2321.
243
244         Example:  -T  mssim:host=localhost,port=2321  or export TPM2TOOLS_TC‐
245         TI="mssim:host=localhost,port=2321"
246
247       · abrmd: For the abrmd TCTI, the configuration string format is  a  se‐
248         ries  of  simple  key value pairs separated by a ',' character.  Each
249         key and value string are separated by a '=' character.
250
251         · TCTI abrmd supports two keys:
252
253           1. 'bus_name' : The name of  the  tabrmd  service  on  the  bus  (a
254              string).
255
256           2. 'bus_type' : The type of the dbus instance (a string) limited to
257              'session' and 'system'.
258
259         Specify the tabrmd tcti name and a config string of  bus_name=com.ex‐
260         ample.FooBar:
261
262         \--tcti=tabrmd:bus_name=com.example.FooBar
263
264         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
265         sion:
266
267         \--tcti:bus_type=session
268
269         NOTE: abrmd and tabrmd are synonymous.  the various known  TCTI  mod‐
270         ules.
271

EXAMPLES

273   Set owner, endorsement and lockout authorizations to an empty value
274              tpm2_clear lockoutpasswd
275
276   Clear the authorization values on the platform hierarchy
277              tpm2_clear -c p
278

Returns

280       Tools can return any of the following codes:
281
282       · 0 - Success.
283
284       · 1 - General non-specific error.
285
286       · 2 - Options handling error.
287
288       · 3 - Authentication error.
289
290       · 4 - TCTI related error.
291
292       · 5 - Non supported scheme.  Applicable to tpm2_testparams.
293

BUGS

295       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
296

HELP

298       See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
299
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302tpm2-tools                                                       tpm2_clear(1)
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