1tpm2_policynv(1) General Commands Manual tpm2_policynv(1)
2
6 tpm2_policynv(1) - Evaluates policy authorization by comparing a speci‐
7 fied value against the contents in the specified NV Index.
8
10 tpm2_policynv [OPTIONS] [ARGUMENT] [ARGUMENT]
11
13 tpm2_policynv(1) - This command evaluates policy authorization by com‐
14 paring the contents written to an NV index against the one specified in
15 the tool options. The tool takes two arguments - (1) The NV index
16 specified as raw handle or an offset value to the nv handle range
17 “TPM2_HR_NV_INDEX” and (2) Comparison operator for magnitude comparison
18 and or bit test operations. In the specification the NV index holding
19 the data is called operandA and the data that the user specifies to
20 compare is called operandB. The comparison operator can be specified
21 as follows: * “eq” if operandA = operandB * “neq” if operandA !=
22 operandB * “sgt” if signed operandA > signed operandB * “ugt” if un‐
23 signed operandA > unsigned operandB * “slt” if signed operandA < signed
24 operandB * “ult” if unsigned operandA < unsigned operandB * “sge” if
25 signed operandA >= signed operandB * “uge” if unsigned operandA >= un‐
26 signed operandB * “sle” if signed operandA <= unsigned operandB * “ule”
27 if unsigned operandA <= unsigned operandB * “bs” if all bits set in
28 operandA are set in operandB * “bc” if all bits set in operandA are
29 clear in operandB
30
32 • -C, --hierarchy=OBJECT:
33 Specifies the hierarchy used to authorize. Supported options are:
34 • o for TPM_RH_OWNER
36 • p for TPM_RH_PLATFORM
38 • <num> where a hierarchy handle or nv-index may be used.
40 When -C isn’t explicitly passed the index handle will be used to au‐
42 thorize against the index. The index auth value is set via the -p
43 option to tpm2_nvdefine(1).
44 • -P, --auth=AUTH:
46 Specifies the authorization value for the hierarchy.
48 • -L, --policy=FILE:
50 File to save the policy digest.
52 • -S, --session=FILE:
54 The policy session file generated via the -S option to tpm2_star‐
56 tauthsession or saved off of a previous tool run.
57 • --offset=NATURAL_NUMBER:
59 The offset within the NV index to start comparing at. The size of
61 the data starting at offset and ending at size of NV index shall not
62 exceed the size of the operand specified in the options.
63 • --cphash=FILE
65 File path to record the hash of the command parameters. This is com‐
67 monly termed as cpHash. NOTE: When this option is selected, The tool
68 will not actually execute the command, it simply returns a cpHash.
69 • -i, --input=FILE:
71 Specifies the input file with data to compare to NV Index contents.
73 In the standard specification, this is termed as operand or operandB
74 more specifically . It can be specified as a file input or stdin if
75 option value is a “-”.
76 References
79 This collection of options are common to many programs and provide in‐
80 formation that many users may expect.
81 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
83 attempts to invoke the manpager for the tool, however, on failure
84 will output a short tool summary. This is the same behavior if the
85 “man” option argument is specified, however if explicit “man” is re‐
86 quested, the tool will provide errors from man on stderr. If the
87 “no-man” option if specified, or the manpager fails, the short op‐
88 tions will be output to stdout.
89 To successfully use the manpages feature requires the manpages to be
91 installed or on MANPATH, See man(1) for more details.
92 • -v, --version: Display version information for this tool, supported
94 tctis and exit.
95 • -V, --verbose: Increase the information that the tool prints to the
97 console during its execution. When using this option the file and
98 line number are printed.
99 • -Q, --quiet: Silence normal tool output to stdout.
101 • -Z, --enable-errata: Enable the application of errata fixups. Useful
103 if an errata fixup needs to be applied to commands sent to the TPM.
104 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
105 formation many users may expect.
106
108 The TCTI or “Transmission Interface” is the communication mechanism
109 with the TPM. TCTIs can be changed for communication with TPMs across
110 different mediums.
111 To control the TCTI, the tools respect:
113 1. The command line option -T or --tcti
115 2. The environment variable: TPM2TOOLS_TCTI.
117 Note: The command line option always overrides the environment vari‐
119 able.
120 The current known TCTIs are:
122 • tabrmd - The resource manager, called tabrmd
124 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
125 abrmd as a tcti name are synonymous.
126 • mssim - Typically used for communicating to the TPM software simula‐
128 tor.
129 • device - Used when talking directly to a TPM device file.
131 • none - Do not initalize a connection with the TPM. Some tools allow
133 for off-tpm options and thus support not using a TCTI. Tools that do
134 not support it will error when attempted to be used without a TCTI
135 connection. Does not support ANY options and MUST BE presented as
136 the exact text of “none”.
137 The arguments to either the command line option or the environment
139 variable are in the form:
140 <tcti-name>:<tcti-option-config>
142 Specifying an empty string for either the <tcti-name> or <tcti-op‐
144 tion-config> results in the default being used for that portion respec‐
145 tively.
146 TCTI Defaults
148 When a TCTI is not specified, the default TCTI is searched for using
149 dlopen(3) semantics. The tools will search for tabrmd, device and
150 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
151 what TCTI will be chosen as the default by using the -v option to print
152 the version information. The “default-tcti” key-value pair will indi‐
153 cate which of the aforementioned TCTIs is the default.
154 Custom TCTIs
156 Any TCTI that implements the dynamic TCTI interface can be loaded. The
157 tools internally use dlopen(3), and the raw tcti-name value is used for
158 the lookup. Thus, this could be a path to the shared library, or a li‐
159 brary name as understood by dlopen(3) semantics.
160
162 This collection of options are used to configure the various known TCTI
163 modules available:
164 • device: For the device TCTI, the TPM character device file for use by
166 the device TCTI can be specified. The default is /dev/tpm0.
167 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
169 vice:/dev/tpm0”
170 • mssim: For the mssim TCTI, the domain name or IP address and port
172 number used by the simulator can be specified. The default are
173 127.0.0.1 and 2321.
174 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
176 TI=“mssim:host=localhost,port=2321”
177 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
179 ries of simple key value pairs separated by a `,' character. Each
180 key and value string are separated by a `=' character.
181 • TCTI abrmd supports two keys:
183 1. `bus_name' : The name of the tabrmd service on the bus (a
185 string).
186 2. `bus_type' : The type of the dbus instance (a string) limited to
188 `session' and `system'.
189 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
191 ample.FooBar:
192 \--tcti=tabrmd:bus_name=com.example.FooBar
194 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
196 sion:
197 \--tcti:bus_type=session
199 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
201 ules.
202
204 Test if NV index content value is equal to an input number. To do this
205 we first create an NV index of size 1 byte and write a value. Eg.
206 0xAA. Next we attempt to create a policy that becomes valid if the
207 equality comparison operation of the NV index content against the one
208 specified in the tool options.
209 Define the test NV Index and write the value 0xAA to it
211 nv_test_index=0x01500001
212 tpm2_nvdefine -C o -p nvpass $nv_test_index -a "authread|authwrite" -s 1
213 echo "aa" | xxd -r -p | tpm2_nvwrite -P nvpass -i- $nv_test_index
214 Attempt defining policynv with wrong comparison value specified in options.
216 tpm2_startauthsession -S session.ctx --policy-session
217 ### This should fail
218 echo 0xBB | tpm2_policynv -S session.ctx -L policy.nv -i- 0x1500001 eq -P nvpass
219 tpm2_flushcontext session.ctx
220 Attempt defining policynv with right comparison value specified in options.
222 tpm2_startauthsession -S session.ctx --policy-session
223 ### This should pass
224 echo 0xAA | tpm2_policynv -S session.ctx -L policy.nv -i- 0x1500001 eq -P nvpass
225 tpm2_flushcontext session.ctx
226
228 Tools can return any of the following codes:
229 • 0 - Success.
231 • 1 - General non-specific error.
233 • 2 - Options handling error.
235 • 3 - Authentication error.
237 • 4 - TCTI related error.
239 • 5 - Non supported scheme. Applicable to tpm2_testparams.
241
243 It expects a session to be already established via tpm2_startauthses‐
244 sion(1) and requires one of the following:
245 • direct device access
247 • extended session support with tpm2-abrmd.
249 Without it, most resource managers will not save session state between
251 command invocations.
252
254 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
255
257 See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
258 fo/tpm2)
259tpm2-tools tpm2_policynv(1)