1tpm2_clearcontrol(1) General Commands Manual tpm2_clearcontrol(1)
2
6 tpm2_clearcontrol(1) - Set/ Clear TPMA_PERMANENT.disableClear attribute
7 to effectively block/ unblock lockout authorization handle for issuing
8 TPM clear.
9
11 tpm2_clearcontrol [OPTIONS] [ARGUMENT]
12
14 tpm2_clearcontrol(1) - Allows user with knowledge of either lockout
15 auth and or platform hierarchy auth to set disableClear which prevents
16 the lockout authorization's capability to execute tpm2_clear. Only us‐
17 er with authorization knowledge of the platform hierarchy can clear the
18 disableClear. By default it attempts to clear the disableClear bit.
19 Note: Platform hierarchy auth handle can always be used to clear the
21 TPM with tpm2_clear command.
22
24 · -C, --hierarchy=OBJECT:
25 Specifies what auth handle, either platform hierarchy or lockout the
27 tool should operate on. By default it operates on the platform hier‐
28 archy handle. Specify the handle as p|l|platform|lockout.
29 NOTE : Operating on platform hierarchy require platform authentica‐
31 tion.
32 · -P, --auth=AUTH:
34 The authorization value of the hierarchy specified with -C. This
36 tool only respects the Password and HMAC options.
37 · ARGUMENT ** Specify an integer 0|1 or string c|s to clear or set the
39 disableClear attribute.
40 References
43 The type of a context object, whether it is a handle or file name, is
44 determined according to the following logic in-order:
45 · If the argument is a file path, then the file is loaded as a restored
47 TPM transient object.
48 · If the argument is a prefix match on one of:
50 · owner: the owner hierarchy
52 · platform: the platform hierarchy
54 · endorsement: the endorsement hierarchy
56 · lockout: the lockout control persistent object
58 · If the argument argument can be loaded as a number it will be treat
60 as a handle, e.g. 0x81010013 and used directly.OBJECT.
61
63 Authorization for use of an object in TPM2.0 can come in 3 different
64 forms: 1. Password 2. HMAC 3. Sessions
65 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
67 fied".
68 Passwords
70 Passwords are interpreted in the following forms below using prefix
71 identifiers.
72 Note: By default passwords are assumed to be in the string form when
74 they do not have a prefix.
75 String
77 A string password, specified by prefix "str:" or it's absence (raw
78 string without prefix) is not interpreted, and is directly used for au‐
79 thorization.
80 Examples
82 foobar
83 str:foobar
84 Hex-string
86 A hex-string password, specified by prefix "hex:" is converted from a
87 hexidecimal form into a byte array form, thus allowing passwords with
88 non-printable and/or terminal un-friendly characters.
89 Example
91 hex:0x1122334455667788
92 File
94 A file based password, specified be prefix "file:" should be the path
95 of a file containing the password to be read by the tool or a "-" to
96 use stdin. Storing passwords in files prevents information leakage,
97 passwords passed as options can be read from the process list or common
98 shell history features.
99 Examples
101 # to use stdin and be prompted
102 file:-
103 # to use a file from a path
105 file:path/to/password/file
106 # to echo a password via stdin:
108 echo foobar | tpm2_tool -p file:-
109 # to use a bash here-string via stdin:
111 tpm2_tool -p file:- <<< foobar
113 Sessions
115 When using a policy session to authorize the use of an object, prefix
116 the option argument with the session keyword. Then indicate a path to
117 a session file that was created with tpm2_startauthsession(1). Option‐
118 ally, if the session requires an auth value to be sent with the session
119 handle (eg policy password), then append a + and a string as described
120 in the Passwords section.
121 Examples
123 To use a session context file called session.ctx.
124 session:session.ctx
126 To use a session context file called session.ctx AND send the authvalue
128 mypassword.
129 session:session.ctx+mypassword
131 To use a session context file called session.ctx AND send the HEX auth‐
133 value 0x11223344.
134 session:session.ctx+hex:11223344
136 PCR Authorizations
138 You can satisfy a PCR policy using the "pcr:" prefix and the PCR mini‐
139 language. The PCR minilanguage is as follows:
140 <pcr-spec>=<raw-pcr-file>
141 The PCR spec is documented in in the section "PCR bank specifiers".
143 The raw-pcr-file is an optional the output of the raw PCR contents as
145 returned by tpm2_pcrread(1).
146 PCR bank specifiers (common/pcr.md)
148 Examples
150 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
151 er of:
152 pcr:sha256:0,1,2,3
154 specifying AUTH.
156
158 This collection of options are common to many programs and provide in‐
159 formation that many users may expect.
160 · -h, --help=[man|no-man]: Display the tools manpage. By default, it
162 attempts to invoke the manpager for the tool, however, on failure
163 will output a short tool summary. This is the same behavior if the
164 "man" option argument is specified, however if explicit "man" is re‐
165 quested, the tool will provide errors from man on stderr. If the
166 "no-man" option if specified, or the manpager fails, the short op‐
167 tions will be output to stdout.
168 To successfully use the manpages feature requires the manpages to be
170 installed or on MANPATH, See man(1) for more details.
171 · -v, --version: Display version information for this tool, supported
173 tctis and exit.
174 · -V, --verbose: Increase the information that the tool prints to the
176 console during its execution. When using this option the file and
177 line number are printed.
178 · -Q, --quiet: Silence normal tool output to stdout.
180 · -Z, --enable-errata: Enable the application of errata fixups. Useful
182 if an errata fixup needs to be applied to commands sent to the TPM.
183 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
184 formation many users may expect.
185
187 The TCTI or "Transmission Interface" is the communication mechanism
188 with the TPM. TCTIs can be changed for communication with TPMs across
189 different mediums.
190 To control the TCTI, the tools respect:
192 1. The command line option -T or --tcti
194 2. The environment variable: TPM2TOOLS_TCTI.
196 Note: The command line option always overrides the environment vari‐
198 able.
199 The current known TCTIs are:
201 · tabrmd - The resource manager, called tabrmd
203 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
204 abrmd as a tcti name are synonymous.
205 · mssim - Typically used for communicating to the TPM software simula‐
207 tor.
208 · device - Used when talking directly to a TPM device file.
210 · none - Do not initalize a connection with the TPM. Some tools allow
212 for off-tpm options and thus support not using a TCTI. Tools that do
213 not support it will error when attempted to be used without a TCTI
214 connection. Does not support ANY options and MUST BE presented as
215 the exact text of "none".
216 The arguments to either the command line option or the environment
218 variable are in the form:
219 <tcti-name>:<tcti-option-config>
221 Specifying an empty string for either the <tcti-name> or <tcti-op‐
223 tion-config> results in the default being used for that portion respec‐
224 tively.
225 TCTI Defaults
227 When a TCTI is not specified, the default TCTI is searched for using
228 dlopen(3) semantics. The tools will search for tabrmd, device and
229 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
230 what TCTI will be chosen as the default by using the -v option to print
231 the version information. The "default-tcti" key-value pair will indi‐
232 cate which of the aforementioned TCTIs is the default.
233 Custom TCTIs
235 Any TCTI that implements the dynamic TCTI interface can be loaded. The
236 tools internally use dlopen(3), and the raw tcti-name value is used for
237 the lookup. Thus, this could be a path to the shared library, or a li‐
238 brary name as understood by dlopen(3) semantics.
239
241 This collection of options are used to configure the various known TCTI
242 modules available:
243 · device: For the device TCTI, the TPM character device file for use by
245 the device TCTI can be specified. The default is /dev/tpm0.
246 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
248 vice:/dev/tpm0"
249 · mssim: For the mssim TCTI, the domain name or IP address and port
251 number used by the simulator can be specified. The default are
252 127.0.0.1 and 2321.
253 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
255 TI="mssim:host=localhost,port=2321"
256 · abrmd: For the abrmd TCTI, the configuration string format is a se‐
258 ries of simple key value pairs separated by a ',' character. Each
259 key and value string are separated by a '=' character.
260 · TCTI abrmd supports two keys:
262 1. 'bus_name' : The name of the tabrmd service on the bus (a
264 string).
265 2. 'bus_type' : The type of the dbus instance (a string) limited to
267 'session' and 'system'.
268 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
270 ample.FooBar:
271 \--tcti=tabrmd:bus_name=com.example.FooBar
273 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
275 sion:
276 \--tcti:bus_type=session
278 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
280 ules.
281
283 Set the disableClear to block the lockout authorization's access
284 to TPM clear
285 tpm2_clearcontrol -C l s
287 Clear the disableClear to unblock lockout authorization for TPM
289 clear
290 tpm2_clearcontrol -C p c
292
294 Tools can return any of the following codes:
295 · 0 - Success.
297 · 1 - General non-specific error.
299 · 2 - Options handling error.
301 · 3 - Authentication error.
303 · 4 - TCTI related error.
305 · 5 - Non supported scheme. Applicable to tpm2_testparams.
307
309 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
310
312 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
313tpm2-tools tpm2_clearcontrol(1)