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 · -i, --input=FILE:
65 Specifies the input file with data to compare to NV Index contents.
67 In the standard specification, this is termed as operand or operandB
68 more specifically . It can be specified as a file input or stdin if
69 option value is a "-".
70 References
73 This collection of options are common to many programs and provide in‐
74 formation that many users may expect.
75 · -h, --help=[man|no-man]: Display the tools manpage. By default, it
77 attempts to invoke the manpager for the tool, however, on failure
78 will output a short tool summary. This is the same behavior if the
79 "man" option argument is specified, however if explicit "man" is re‐
80 quested, the tool will provide errors from man on stderr. If the
81 "no-man" option if specified, or the manpager fails, the short op‐
82 tions will be output to stdout.
83 To successfully use the manpages feature requires the manpages to be
85 installed or on MANPATH, See man(1) for more details.
86 · -v, --version: Display version information for this tool, supported
88 tctis and exit.
89 · -V, --verbose: Increase the information that the tool prints to the
91 console during its execution. When using this option the file and
92 line number are printed.
93 · -Q, --quiet: Silence normal tool output to stdout.
95 · -Z, --enable-errata: Enable the application of errata fixups. Useful
97 if an errata fixup needs to be applied to commands sent to the TPM.
98 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
99 formation many users may expect.
100
102 The TCTI or "Transmission Interface" is the communication mechanism
103 with the TPM. TCTIs can be changed for communication with TPMs across
104 different mediums.
105 To control the TCTI, the tools respect:
107 1. The command line option -T or --tcti
109 2. The environment variable: TPM2TOOLS_TCTI.
111 Note: The command line option always overrides the environment vari‐
113 able.
114 The current known TCTIs are:
116 · tabrmd - The resource manager, called tabrmd
118 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
119 abrmd as a tcti name are synonymous.
120 · mssim - Typically used for communicating to the TPM software simula‐
122 tor.
123 · device - Used when talking directly to a TPM device file.
125 · none - Do not initalize a connection with the TPM. Some tools allow
127 for off-tpm options and thus support not using a TCTI. Tools that do
128 not support it will error when attempted to be used without a TCTI
129 connection. Does not support ANY options and MUST BE presented as
130 the exact text of "none".
131 The arguments to either the command line option or the environment
133 variable are in the form:
134 <tcti-name>:<tcti-option-config>
136 Specifying an empty string for either the <tcti-name> or <tcti-op‐
138 tion-config> results in the default being used for that portion respec‐
139 tively.
140 TCTI Defaults
142 When a TCTI is not specified, the default TCTI is searched for using
143 dlopen(3) semantics. The tools will search for tabrmd, device and
144 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
145 what TCTI will be chosen as the default by using the -v option to print
146 the version information. The "default-tcti" key-value pair will indi‐
147 cate which of the aforementioned TCTIs is the default.
148 Custom TCTIs
150 Any TCTI that implements the dynamic TCTI interface can be loaded. The
151 tools internally use dlopen(3), and the raw tcti-name value is used for
152 the lookup. Thus, this could be a path to the shared library, or a li‐
153 brary name as understood by dlopen(3) semantics.
154
156 This collection of options are used to configure the various known TCTI
157 modules available:
158 · device: For the device TCTI, the TPM character device file for use by
160 the device TCTI can be specified. The default is /dev/tpm0.
161 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
163 vice:/dev/tpm0"
164 · mssim: For the mssim TCTI, the domain name or IP address and port
166 number used by the simulator can be specified. The default are
167 127.0.0.1 and 2321.
168 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
170 TI="mssim:host=localhost,port=2321"
171 · abrmd: For the abrmd TCTI, the configuration string format is a se‐
173 ries of simple key value pairs separated by a ',' character. Each
174 key and value string are separated by a '=' character.
175 · TCTI abrmd supports two keys:
177 1. 'bus_name' : The name of the tabrmd service on the bus (a
179 string).
180 2. 'bus_type' : The type of the dbus instance (a string) limited to
182 'session' and 'system'.
183 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
185 ample.FooBar:
186 \--tcti=tabrmd:bus_name=com.example.FooBar
188 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
190 sion:
191 \--tcti:bus_type=session
193 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
195 ules.
196
198 Test if NV index content value is equal to an input number. To do this
199 we first create an NV index of size 1 byte and write a value. Eg.
200 0xAA. Next we attempt to create a policy that becomes valid if the
201 equality comparison operation of the NV index content against the one
202 specified in the tool options.
203 Define the test NV Index and write the value 0xAA to it
205 nv_test_index=0x01500001
206 tpm2_nvdefine -C o -p nvpass $nv_test_index -a "authread|authwrite" -s 1
207 echo "aa" | xxd -r -p | tpm2_nvwrite -P nvpass -i- $nv_test_index
208 Attempt defining policynv with wrong comparison value specified in
210 options.
211 tpm2_startauthsession -S session.ctx --policy-session
213 ### This should fail
214 echo 0xBB | tpm2_policynv -S session.ctx -L policy.nv -i- 0x1500001 eq -P nvpass
215 tpm2_flushcontext session.ctx
216 Attempt defining policynv with right comparison value specified in
218 options.
219 tpm2_startauthsession -S session.ctx --policy-session
221 ### This should pass
222 echo 0xAA | tpm2_policynv -S session.ctx -L policy.nv -i- 0x1500001 eq -P nvpass
223 tpm2_flushcontext session.ctx
224
226 Tools can return any of the following codes:
227 · 0 - Success.
229 · 1 - General non-specific error.
231 · 2 - Options handling error.
233 · 3 - Authentication error.
235 · 4 - TCTI related error.
237 · 5 - Non supported scheme. Applicable to tpm2_testparams.
239
241 It expects a session to be already established via tpm2_startauthses‐
242 sion(1) and requires one of the following:
243 · direct device access
245 · extended session support with tpm2-abrmd.
247 Without it, most resource managers will not save session state between
249 command invocations.
250
252 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
253
255 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
256tpm2-tools tpm2_policynv(1)