1tpm2_nvwritelock(1) General Commands Manual tpm2_nvwritelock(1)
2
6 tpm2_nvwritelock(1) - Lock the Non-Volatile (NV) index for further
7 writes.
8
10 tpm2_nvwritelock [OPTIONS] [ARGUMENT]
11
13 tpm2_nvwritelock(1) - Lock the Non-Volatile (NV) index for further
14 writes. The lock on the NV index is unlocked when the TPM is restarted
15 and the NV index becomes writable again. The index can be specified as
16 raw handle or an offset value to the nv handle range "TPM2_HR_NV_IN‐
17 DEX".
18
20 · -C, --hierarchy=OBJECT:
21 Specifies the hierarchy used to authorize. Supported options are:
22 · o for TPM_RH_OWNER
24 · p for TPM_RH_PLATFORM
26 · <num> where a hierarchy handle or nv-index may be used.
28 When -C isn't explicitly passed the index handle will be used to au‐
30 thorize against the index. The index auth value is set via the -p
31 option to tpm2_nvdefine(1).
32 · -P, --auth=AUTH:
34 Specifies the authorization value for the hierarchy.
36 · --global:
38 Lock all NV indices with attribute TPMA_NV_GLOBALLOCK. This option
40 does not require an NV index or offset as an argument.
41 · ARGUMENT the command line argument specifies the NV index or offset
43 number.
44 References
47 The type of a context object, whether it is a handle or file name, is
48 determined according to the following logic in-order:
49 · If the argument is a file path, then the file is loaded as a restored
51 TPM transient object.
52 · If the argument is a prefix match on one of:
54 · owner: the owner hierarchy
56 · platform: the platform hierarchy
58 · endorsement: the endorsement hierarchy
60 · lockout: the lockout control persistent object
62 · If the argument argument can be loaded as a number it will be treat
64 as a handle, e.g. 0x81010013 and used directly.OBJECT.
65
67 Authorization for use of an object in TPM2.0 can come in 3 different
68 forms: 1. Password 2. HMAC 3. Sessions
69 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
71 fied".
72 Passwords
74 Passwords are interpreted in the following forms below using prefix
75 identifiers.
76 Note: By default passwords are assumed to be in the string form when
78 they do not have a prefix.
79 String
81 A string password, specified by prefix "str:" or it's absence (raw
82 string without prefix) is not interpreted, and is directly used for au‐
83 thorization.
84 Examples
86 foobar
87 str:foobar
88 Hex-string
90 A hex-string password, specified by prefix "hex:" is converted from a
91 hexidecimal form into a byte array form, thus allowing passwords with
92 non-printable and/or terminal un-friendly characters.
93 Example
95 hex:0x1122334455667788
96 File
98 A file based password, specified be prefix "file:" should be the path
99 of a file containing the password to be read by the tool or a "-" to
100 use stdin. Storing passwords in files prevents information leakage,
101 passwords passed as options can be read from the process list or common
102 shell history features.
103 Examples
105 # to use stdin and be prompted
106 file:-
107 # to use a file from a path
109 file:path/to/password/file
110 # to echo a password via stdin:
112 echo foobar | tpm2_tool -p file:-
113 # to use a bash here-string via stdin:
115 tpm2_tool -p file:- <<< foobar
117 Sessions
119 When using a policy session to authorize the use of an object, prefix
120 the option argument with the session keyword. Then indicate a path to
121 a session file that was created with tpm2_startauthsession(1). Option‐
122 ally, if the session requires an auth value to be sent with the session
123 handle (eg policy password), then append a + and a string as described
124 in the Passwords section.
125 Examples
127 To use a session context file called session.ctx.
128 session:session.ctx
130 To use a session context file called session.ctx AND send the authvalue
132 mypassword.
133 session:session.ctx+mypassword
135 To use a session context file called session.ctx AND send the HEX auth‐
137 value 0x11223344.
138 session:session.ctx+hex:11223344
140 PCR Authorizations
142 You can satisfy a PCR policy using the "pcr:" prefix and the PCR mini‐
143 language. The PCR minilanguage is as follows:
144 <pcr-spec>=<raw-pcr-file>
145 The PCR spec is documented in in the section "PCR bank specifiers".
147 The raw-pcr-file is an optional the output of the raw PCR contents as
149 returned by tpm2_pcrread(1).
150 PCR bank specifiers (common/pcr.md)
152 Examples
154 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
155 er of:
156 pcr:sha256:0,1,2,3
158 specifying AUTH.
160
162 This collection of options are common to many programs and provide in‐
163 formation that many users may expect.
164 · -h, --help=[man|no-man]: Display the tools manpage. By default, it
166 attempts to invoke the manpager for the tool, however, on failure
167 will output a short tool summary. This is the same behavior if the
168 "man" option argument is specified, however if explicit "man" is re‐
169 quested, the tool will provide errors from man on stderr. If the
170 "no-man" option if specified, or the manpager fails, the short op‐
171 tions will be output to stdout.
172 To successfully use the manpages feature requires the manpages to be
174 installed or on MANPATH, See man(1) for more details.
175 · -v, --version: Display version information for this tool, supported
177 tctis and exit.
178 · -V, --verbose: Increase the information that the tool prints to the
180 console during its execution. When using this option the file and
181 line number are printed.
182 · -Q, --quiet: Silence normal tool output to stdout.
184 · -Z, --enable-errata: Enable the application of errata fixups. Useful
186 if an errata fixup needs to be applied to commands sent to the TPM.
187 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
188 formation many users may expect.
189
191 The TCTI or "Transmission Interface" is the communication mechanism
192 with the TPM. TCTIs can be changed for communication with TPMs across
193 different mediums.
194 To control the TCTI, the tools respect:
196 1. The command line option -T or --tcti
198 2. The environment variable: TPM2TOOLS_TCTI.
200 Note: The command line option always overrides the environment vari‐
202 able.
203 The current known TCTIs are:
205 · tabrmd - The resource manager, called tabrmd
207 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
208 abrmd as a tcti name are synonymous.
209 · mssim - Typically used for communicating to the TPM software simula‐
211 tor.
212 · device - Used when talking directly to a TPM device file.
214 · none - Do not initalize a connection with the TPM. Some tools allow
216 for off-tpm options and thus support not using a TCTI. Tools that do
217 not support it will error when attempted to be used without a TCTI
218 connection. Does not support ANY options and MUST BE presented as
219 the exact text of "none".
220 The arguments to either the command line option or the environment
222 variable are in the form:
223 <tcti-name>:<tcti-option-config>
225 Specifying an empty string for either the <tcti-name> or <tcti-op‐
227 tion-config> results in the default being used for that portion respec‐
228 tively.
229 TCTI Defaults
231 When a TCTI is not specified, the default TCTI is searched for using
232 dlopen(3) semantics. The tools will search for tabrmd, device and
233 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
234 what TCTI will be chosen as the default by using the -v option to print
235 the version information. The "default-tcti" key-value pair will indi‐
236 cate which of the aforementioned TCTIs is the default.
237 Custom TCTIs
239 Any TCTI that implements the dynamic TCTI interface can be loaded. The
240 tools internally use dlopen(3), and the raw tcti-name value is used for
241 the lookup. Thus, this could be a path to the shared library, or a li‐
242 brary name as understood by dlopen(3) semantics.
243
245 This collection of options are used to configure the various known TCTI
246 modules available:
247 · device: For the device TCTI, the TPM character device file for use by
249 the device TCTI can be specified. The default is /dev/tpm0.
250 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
252 vice:/dev/tpm0"
253 · mssim: For the mssim TCTI, the domain name or IP address and port
255 number used by the simulator can be specified. The default are
256 127.0.0.1 and 2321.
257 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
259 TI="mssim:host=localhost,port=2321"
260 · abrmd: For the abrmd TCTI, the configuration string format is a se‐
262 ries of simple key value pairs separated by a ',' character. Each
263 key and value string are separated by a '=' character.
264 · TCTI abrmd supports two keys:
266 1. 'bus_name' : The name of the tabrmd service on the bus (a
268 string).
269 2. 'bus_type' : The type of the dbus instance (a string) limited to
271 'session' and 'system'.
272 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
274 ample.FooBar:
275 \--tcti=tabrmd:bus_name=com.example.FooBar
277 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
279 sion:
280 \--tcti:bus_type=session
282 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
284 ules.
285
287 Lock an index
288 tpm2_nvdefine -C o -s 32 \
289 -a "ownerread|policywrite|ownerwrite|writedefine" 1
290 echo "foobar" > nv.writelock
292 tpm2_nvwrite -C o -i nv.writelock 1
294 tpm2_nvwritelock -C o 1
296 # fails with "NV access locked"
298 tpm2_nvwrite -C o -i nv.writelock 1
299 Global Lock
301 tpm2_nvdefine -C o -s 32 \
302 -a "ownerread|policywrite|ownerwrite|globallock" 1
303 tpm2_nvwritelock -C o --global
305 # this command fails with "NV access locked".
307 echo foo | tpm2_nvwrite -C o -i- 1
308
310 Tools can return any of the following codes:
311 · 0 - Success.
313 · 1 - General non-specific error.
315 · 2 - Options handling error.
317 · 3 - Authentication error.
319 · 4 - TCTI related error.
321 · 5 - Non supported scheme. Applicable to tpm2_testparams.
323
325 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
326
328 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
329tpm2-tools tpm2_nvwritelock(1)