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 • --cphash=FILE
43 File path to record the hash of the command parameters. This is com‐
45 monly termed as cpHash. NOTE: When this option is selected, The tool
46 will not actually execute the command, it simply returns a cpHash un‐
47 less rphash is also required.
48 • --rphash=FILE
50 File path to record the hash of the response parameters. This is
52 commonly termed as rpHash.
53 • -S, --session=FILE:
55 The session created using tpm2_startauthsession. This can be used to
57 specify an auxiliary session for auditing and or encryption/decryp‐
58 tion of the parameters.
59 • -n, --name=FILE:
61 The name of the NV index that must be provided when only calculating
63 the cpHash without actually dispatching the command to the TPM.
64 • ARGUMENT the command line argument specifies the NV index or offset
66 number.
67 References
70 The type of a context object, whether it is a handle or file name, is
71 determined according to the following logic in-order:
72 • If the argument is a file path, then the file is loaded as a restored
74 TPM transient object.
75 • If the argument is a prefix match on one of:
77 • owner: the owner hierarchy
79 • platform: the platform hierarchy
81 • endorsement: the endorsement hierarchy
83 • lockout: the lockout control persistent object
85 • If the argument argument can be loaded as a number it will be treat
87 as a handle, e.g. 0x81010013 and used directly._OBJECT_.
88
90 Authorization for use of an object in TPM2.0 can come in 3 different
91 forms: 1. Password 2. HMAC 3. Sessions
92 NOTE: “Authorizations default to the EMPTY PASSWORD when not speci‐
94 fied”.
95 Passwords
97 Passwords are interpreted in the following forms below using prefix
98 identifiers.
99 Note: By default passwords are assumed to be in the string form when
101 they do not have a prefix.
102 String
104 A string password, specified by prefix “str:” or it’s absence (raw
105 string without prefix) is not interpreted, and is directly used for au‐
106 thorization.
107 Examples
109 foobar
110 str:foobar
111 Hex-string
113 A hex-string password, specified by prefix “hex:” is converted from a
114 hexidecimal form into a byte array form, thus allowing passwords with
115 non-printable and/or terminal un-friendly characters.
116 Example
118 hex:1122334455667788
119 File
121 A file based password, specified be prefix “file:” should be the path
122 of a file containing the password to be read by the tool or a “-” to
123 use stdin. Storing passwords in files prevents information leakage,
124 passwords passed as options can be read from the process list or common
125 shell history features.
126 Examples
128 # to use stdin and be prompted
129 file:-
130 # to use a file from a path
132 file:path/to/password/file
133 # to echo a password via stdin:
135 echo foobar | tpm2_tool -p file:-
136 # to use a bash here-string via stdin:
138 tpm2_tool -p file:- <<< foobar
140 Sessions
142 When using a policy session to authorize the use of an object, prefix
143 the option argument with the session keyword. Then indicate a path to
144 a session file that was created with tpm2_startauthsession(1). Option‐
145 ally, if the session requires an auth value to be sent with the session
146 handle (eg policy password), then append a + and a string as described
147 in the Passwords section.
148 Examples
150 To use a session context file called session.ctx.
151 session:session.ctx
153 To use a session context file called session.ctx AND send the authvalue
155 mypassword.
156 session:session.ctx+mypassword
158 To use a session context file called session.ctx AND send the HEX auth‐
160 value 0x11223344.
161 session:session.ctx+hex:11223344
163 PCR Authorizations
165 You can satisfy a PCR policy using the “pcr:” prefix and the PCR mini‐
166 language. The PCR minilanguage is as follows:
167 <pcr-spec>=<raw-pcr-file>
168 The PCR spec is documented in in the section “PCR bank specifiers”.
170 The raw-pcr-file is an optional argument that contains the output of
172 the raw PCR contents as returned by tpm2_pcrread(1).
173 PCR bank specifiers (pcr.md)
175 Examples
177 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
178 er of:
179 pcr:sha256:0,1,2,3
181 specifying AUTH.
183
185 This collection of options are common to many programs and provide in‐
186 formation that many users may expect.
187 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
189 attempts to invoke the manpager for the tool, however, on failure
190 will output a short tool summary. This is the same behavior if the
191 “man” option argument is specified, however if explicit “man” is re‐
192 quested, the tool will provide errors from man on stderr. If the
193 “no-man” option if specified, or the manpager fails, the short op‐
194 tions will be output to stdout.
195 To successfully use the manpages feature requires the manpages to be
197 installed or on MANPATH, See man(1) for more details.
198 • -v, --version: Display version information for this tool, supported
200 tctis and exit.
201 • -V, --verbose: Increase the information that the tool prints to the
203 console during its execution. When using this option the file and
204 line number are printed.
205 • -Q, --quiet: Silence normal tool output to stdout.
207 • -Z, --enable-errata: Enable the application of errata fixups. Useful
209 if an errata fixup needs to be applied to commands sent to the TPM.
210 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
211 formation many users may expect.
212
214 The TCTI or “Transmission Interface” is the communication mechanism
215 with the TPM. TCTIs can be changed for communication with TPMs across
216 different mediums.
217 To control the TCTI, the tools respect:
219 1. The command line option -T or --tcti
221 2. The environment variable: TPM2TOOLS_TCTI.
223 Note: The command line option always overrides the environment vari‐
225 able.
226 The current known TCTIs are:
228 • tabrmd - The resource manager, called tabrmd
230 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
231 abrmd as a tcti name are synonymous.
232 • mssim - Typically used for communicating to the TPM software simula‐
234 tor.
235 • device - Used when talking directly to a TPM device file.
237 • none - Do not initalize a connection with the TPM. Some tools allow
239 for off-tpm options and thus support not using a TCTI. Tools that do
240 not support it will error when attempted to be used without a TCTI
241 connection. Does not support ANY options and MUST BE presented as
242 the exact text of “none”.
243 The arguments to either the command line option or the environment
245 variable are in the form:
246 <tcti-name>:<tcti-option-config>
248 Specifying an empty string for either the <tcti-name> or <tcti-op‐
250 tion-config> results in the default being used for that portion respec‐
251 tively.
252 TCTI Defaults
254 When a TCTI is not specified, the default TCTI is searched for using
255 dlopen(3) semantics. The tools will search for tabrmd, device and
256 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
257 what TCTI will be chosen as the default by using the -v option to print
258 the version information. The “default-tcti” key-value pair will indi‐
259 cate which of the aforementioned TCTIs is the default.
260 Custom TCTIs
262 Any TCTI that implements the dynamic TCTI interface can be loaded. The
263 tools internally use dlopen(3), and the raw tcti-name value is used for
264 the lookup. Thus, this could be a path to the shared library, or a li‐
265 brary name as understood by dlopen(3) semantics.
266
268 This collection of options are used to configure the various known TCTI
269 modules available:
270 • device: For the device TCTI, the TPM character device file for use by
272 the device TCTI can be specified. The default is /dev/tpm0.
273 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
275 vice:/dev/tpm0”
276 • mssim: For the mssim TCTI, the domain name or IP address and port
278 number used by the simulator can be specified. The default are
279 127.0.0.1 and 2321.
280 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
282 TI=“mssim:host=localhost,port=2321”
283 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
285 ries of simple key value pairs separated by a `,' character. Each
286 key and value string are separated by a `=' character.
287 • TCTI abrmd supports two keys:
289 1. `bus_name' : The name of the tabrmd service on the bus (a
291 string).
292 2. `bus_type' : The type of the dbus instance (a string) limited to
294 `session' and `system'.
295 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
297 ample.FooBar:
298 \--tcti=tabrmd:bus_name=com.example.FooBar
300 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
302 sion:
303 \--tcti:bus_type=session
305 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
307 ules.
308
310 Lock an index
311 tpm2_nvdefine -C o -s 32 \
312 -a "ownerread|policywrite|ownerwrite|writedefine" 1
313 echo "foobar" > nv.writelock
315 tpm2_nvwrite -C o -i nv.writelock 1
317 tpm2_nvwritelock -C o 1
319 # fails with "NV access locked"
321 tpm2_nvwrite -C o -i nv.writelock 1
322 Global Lock
324 tpm2_nvdefine -C o -s 32 \
325 -a "ownerread|policywrite|ownerwrite|globallock" 1
326 tpm2_nvwritelock -C o --global
328 # this command fails with "NV access locked".
330 echo foo | tpm2_nvwrite -C o -i- 1
331
333 Tools can return any of the following codes:
334 • 0 - Success.
336 • 1 - General non-specific error.
338 • 2 - Options handling error.
340 • 3 - Authentication error.
342 • 4 - TCTI related error.
344 • 5 - Non supported scheme. Applicable to tpm2_testparams.
346
348 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
349
351 See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
352 fo/tpm2)
353tpm2-tools tpm2_nvwritelock(1)