1tpm2_clear(1) General Commands Manual tpm2_clear(1)
2
6 tpm2_clear(1) - Clears lockout, endorsement and owner hierarchy autho‐
7 rization values.
8
10 tpm2_clear [OPTIONS] [ARGUMENT]
11
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 NOTE: All objects created under the respective hierarchies are lost.
18
20 · -c, --auth-hierarchy=OBJECT:
21 Specifies the hierarchy the tools should operate on. By default it
23 operates on the lockout hierarchy.
24 NOTE : Operating on platform hierarchy require platform authentica‐
26 tion.
27 · ARGUMENT the command line argument specifies the AUTH to be set for
29 the object specified with -c.
30 References
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 · If the argument is a file path, then the file is loaded as a restored
37 TPM transient object.
38 · If the argument is a prefix match on one of:
40 · owner: the owner hierarchy
42 · platform: the platform hierarchy
44 · endorsement: the endorsement hierarchy
46 · lockout: the lockout control persistent object
48 · 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
53 Authorization for use of an object in TPM2.0 can come in 3 different
54 forms: 1. Password 2. HMAC 3. Sessions
55 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
57 fied".
58 Passwords
60 Passwords are interpreted in the following forms below using prefix
61 identifiers.
62 Note: By default passwords are assumed to be in the string form when
64 they do not have a prefix.
65 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 Examples
72 foobar
73 str:foobar
74 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 Example
81 hex:0x1122334455667788
82 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 Examples
91 # to use stdin and be prompted
92 file:-
93 # to use a file from a path
95 file:path/to/password/file
96 # to echo a password via stdin:
98 echo foobar | tpm2_tool -p file:-
99 # to use a bash here-string via stdin:
101 tpm2_tool -p file:- <<< foobar
103 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 Examples
113 To use a session context file called session.ctx.
114 session:session.ctx
116 To use a session context file called session.ctx AND send the authvalue
118 mypassword.
119 session:session.ctx+mypassword
121 To use a session context file called session.ctx AND send the HEX auth‐
123 value 0x11223344.
124 session:session.ctx+hex:11223344
126 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 The PCR spec is documented in in the section "PCR bank specifiers".
133 The raw-pcr-file is an optional the output of the raw PCR contents as
135 returned by tpm2_pcrread(1).
136 PCR bank specifiers (common/pcr.md)
138 Examples
140 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
141 er of:
142 pcr:sha256:0,1,2,3
144 specifying AUTH.
146
148 This collection of options are common to many programs and provide in‐
149 formation that many users may expect.
150 · -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 To successfully use the manpages feature requires the manpages to be
160 installed or on MANPATH, See man(1) for more details.
161 · -v, --version: Display version information for this tool, supported
163 tctis and exit.
164 · -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 · -Q, --quiet: Silence normal tool output to stdout.
170 · -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
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 To control the TCTI, the tools respect:
182 1. The command line option -T or --tcti
184 2. The environment variable: TPM2TOOLS_TCTI.
186 Note: The command line option always overrides the environment vari‐
188 able.
189 The current known TCTIs are:
191 · 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 · mssim - Typically used for communicating to the TPM software simula‐
197 tor.
198 · device - Used when talking directly to a TPM device file.
200 · 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 The arguments to either the command line option or the environment
208 variable are in the form:
209 <tcti-name>:<tcti-option-config>
211 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 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 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
231 This collection of options are used to configure the various known TCTI
232 modules available:
233 · 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 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
238 vice:/dev/tpm0"
239 · 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 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
245 TI="mssim:host=localhost,port=2321"
246 · 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 · TCTI abrmd supports two keys:
252 1. 'bus_name' : The name of the tabrmd service on the bus (a
254 string).
255 2. 'bus_type' : The type of the dbus instance (a string) limited to
257 'session' and 'system'.
258 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
260 ample.FooBar:
261 \--tcti=tabrmd:bus_name=com.example.FooBar
263 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
265 sion:
266 \--tcti:bus_type=session
268 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
270 ules.
271
273 Set owner, endorsement and lockout authorizations to an empty value
274 tpm2_clear lockoutpasswd
275 Clear the authorization values on the platform hierarchy
277 tpm2_clear -c p
278
280 Tools can return any of the following codes:
281 · 0 - Success.
283 · 1 - General non-specific error.
285 · 2 - Options handling error.
287 · 3 - Authentication error.
289 · 4 - TCTI related error.
291 · 5 - Non supported scheme. Applicable to tpm2_testparams.
293
295 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
296
298 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
299tpm2-tools tpm2_clear(1)