1tpm2_policynvwritten(1) General Commands Manual tpm2_policynvwritten(1)
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6 tpm2_policynvwritten(1) - Restrict TPM object authorization to the
7 written state of an NV index.
8
10 tpm2_policynvwritten [OPTIONS] [ARGUMENT]
11
13 tpm2_policynvwritten(1) - Restricts TPM object authorization to the
14 written state of an NV index. Useful when creating write once NV in‐
15 dexes.
16 As an [ARGUMENT] it takes the expected written state of the NV index.
18 It can be specified as s|c|0|1.
19
21 • -S, --session=FILE:
22 A session file from tpm2_startauthsession(1)’s -S option.
24 • -L, --policy=FILE:
26 File to save the policy digest.
28 • --cphash=FILE
30 File path to record the hash of the command parameters. This is com‐
32 monly termed as cpHash. NOTE: When this option is selected, The tool
33 will not actually execute the command, it simply returns a cpHash.
34 References
37 This collection of options are common to many programs and provide in‐
38 formation that many users may expect.
39 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
41 attempts to invoke the manpager for the tool, however, on failure
42 will output a short tool summary. This is the same behavior if the
43 “man” option argument is specified, however if explicit “man” is re‐
44 quested, the tool will provide errors from man on stderr. If the
45 “no-man” option if specified, or the manpager fails, the short op‐
46 tions will be output to stdout.
47 To successfully use the manpages feature requires the manpages to be
49 installed or on MANPATH, See man(1) for more details.
50 • -v, --version: Display version information for this tool, supported
52 tctis and exit.
53 • -V, --verbose: Increase the information that the tool prints to the
55 console during its execution. When using this option the file and
56 line number are printed.
57 • -Q, --quiet: Silence normal tool output to stdout.
59 • -Z, --enable-errata: Enable the application of errata fixups. Useful
61 if an errata fixup needs to be applied to commands sent to the TPM.
62 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
63 formation many users may expect.
64
66 The TCTI or “Transmission Interface” is the communication mechanism
67 with the TPM. TCTIs can be changed for communication with TPMs across
68 different mediums.
69 To control the TCTI, the tools respect:
71 1. The command line option -T or --tcti
73 2. The environment variable: TPM2TOOLS_TCTI.
75 Note: The command line option always overrides the environment vari‐
77 able.
78 The current known TCTIs are:
80 • tabrmd - The resource manager, called tabrmd
82 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
83 abrmd as a tcti name are synonymous.
84 • mssim - Typically used for communicating to the TPM software simula‐
86 tor.
87 • device - Used when talking directly to a TPM device file.
89 • none - Do not initalize a connection with the TPM. Some tools allow
91 for off-tpm options and thus support not using a TCTI. Tools that do
92 not support it will error when attempted to be used without a TCTI
93 connection. Does not support ANY options and MUST BE presented as
94 the exact text of “none”.
95 The arguments to either the command line option or the environment
97 variable are in the form:
98 <tcti-name>:<tcti-option-config>
100 Specifying an empty string for either the <tcti-name> or <tcti-op‐
102 tion-config> results in the default being used for that portion respec‐
103 tively.
104 TCTI Defaults
106 When a TCTI is not specified, the default TCTI is searched for using
107 dlopen(3) semantics. The tools will search for tabrmd, device and
108 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
109 what TCTI will be chosen as the default by using the -v option to print
110 the version information. The “default-tcti” key-value pair will indi‐
111 cate which of the aforementioned TCTIs is the default.
112 Custom TCTIs
114 Any TCTI that implements the dynamic TCTI interface can be loaded. The
115 tools internally use dlopen(3), and the raw tcti-name value is used for
116 the lookup. Thus, this could be a path to the shared library, or a li‐
117 brary name as understood by dlopen(3) semantics.
118
120 This collection of options are used to configure the various known TCTI
121 modules available:
122 • device: For the device TCTI, the TPM character device file for use by
124 the device TCTI can be specified. The default is /dev/tpm0.
125 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
127 vice:/dev/tpm0”
128 • mssim: For the mssim TCTI, the domain name or IP address and port
130 number used by the simulator can be specified. The default are
131 127.0.0.1 and 2321.
132 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
134 TI=“mssim:host=localhost,port=2321”
135 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
137 ries of simple key value pairs separated by a `,' character. Each
138 key and value string are separated by a `=' character.
139 • TCTI abrmd supports two keys:
141 1. `bus_name' : The name of the tabrmd service on the bus (a
143 string).
144 2. `bus_type' : The type of the dbus instance (a string) limited to
146 `session' and `system'.
147 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
149 ample.FooBar:
150 \--tcti=tabrmd:bus_name=com.example.FooBar
152 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
154 sion:
155 \--tcti:bus_type=session
157 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
159 ules.
160
162 Create a write once NV index. To do this the NV index is defined with
163 a write policy that is valid only if the NV index attribute “TP‐
164 MA_NV_WRITTEN” was never set.
165 Define the NV index write policy
167 tpm2_startauthsession -S session.dat
168 tpm2_policycommandcode -S session.dat TPM2_CC_NV_Write
169 tpm2_policynvwritten -S session.dat -L nvwrite.policy c
170 tpm2_flushcontext session.dat
171 Define the NV index with the policy
173 tpm2_nvdefine -s 1 -a "authread|policywrite" -p nvrdpass -L nvwrite.policy
174 Write the NV index by satisfying the policy
176 tpm2_startauthsession -S session.dat --policy-session
177 tpm2_policycommandcode -S session.dat TPM2_CC_NV_Write
178 tpm2_policynvwritten -S session.dat c
179 echo 0xAA | xxd -r -p | tpm2_nvwrite 0x01000000 -i- -P session:session.dat
180 tpm2_flushcontext session.dat
181
183 Tools can return any of the following codes:
184 • 0 - Success.
186 • 1 - General non-specific error.
188 • 2 - Options handling error.
190 • 3 - Authentication error.
192 • 4 - TCTI related error.
194 • 5 - Non supported scheme. Applicable to tpm2_testparams.
196
198 It expects a session to be already established via tpm2_startauthses‐
199 sion(1) and requires one of the following:
200 • direct device access
202 • extended session support with tpm2-abrmd.
204 Without it, most resource managers will not save session state between
206 command invocations.
207
209 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
210
212 See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
213 fo/tpm2)
214tpm2-tools tpm2_policynvwritten(1)