1tpm2_policyrestart(1) General Commands Manual tpm2_policyrestart(1)
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6 tpm2_policyrestart(1) - Restart an existing session with the TPM.
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9 tpm2_policyrestart [OPTIONS]
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12 tpm2_policyrestart(1) - Restarts a session with the TPM back to it’s
13 initial state. This is useful when the TPM gives one a
14 TPM_RC_PCR_CHANGED (0x00000128) error code when using a PCR policy ses‐
15 sion.
16 This will be returned if a PCR state affecting policy is altered during
18 the session. One could restart the session and try again, however, the
19 PCR state would still need to satisfy the policy.
20
22 • -S, --session=FILE:
23 Optional, A session file from tpm2_startauthsession(1)’s -S option.
25 This session is used in lieu of starting a session and using the PCR
26 policy options.
27 References
30 This collection of options are common to many programs and provide in‐
31 formation that many users may expect.
32 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
34 attempts to invoke the manpager for the tool, however, on failure
35 will output a short tool summary. This is the same behavior if the
36 “man” option argument is specified, however if explicit “man” is re‐
37 quested, the tool will provide errors from man on stderr. If the
38 “no-man” option if specified, or the manpager fails, the short op‐
39 tions will be output to stdout.
40 To successfully use the manpages feature requires the manpages to be
42 installed or on MANPATH, See man(1) for more details.
43 • -v, --version: Display version information for this tool, supported
45 tctis and exit.
46 • -V, --verbose: Increase the information that the tool prints to the
48 console during its execution. When using this option the file and
49 line number are printed.
50 • -Q, --quiet: Silence normal tool output to stdout.
52 • -Z, --enable-errata: Enable the application of errata fixups. Useful
54 if an errata fixup needs to be applied to commands sent to the TPM.
55 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
56 formation many users may expect.
57
59 The TCTI or “Transmission Interface” is the communication mechanism
60 with the TPM. TCTIs can be changed for communication with TPMs across
61 different mediums.
62 To control the TCTI, the tools respect:
64 1. The command line option -T or --tcti
66 2. The environment variable: TPM2TOOLS_TCTI.
68 Note: The command line option always overrides the environment vari‐
70 able.
71 The current known TCTIs are:
73 • tabrmd - The resource manager, called tabrmd
75 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
76 abrmd as a tcti name are synonymous.
77 • mssim - Typically used for communicating to the TPM software simula‐
79 tor.
80 • device - Used when talking directly to a TPM device file.
82 • none - Do not initalize a connection with the TPM. Some tools allow
84 for off-tpm options and thus support not using a TCTI. Tools that do
85 not support it will error when attempted to be used without a TCTI
86 connection. Does not support ANY options and MUST BE presented as
87 the exact text of “none”.
88 The arguments to either the command line option or the environment
90 variable are in the form:
91 <tcti-name>:<tcti-option-config>
93 Specifying an empty string for either the <tcti-name> or <tcti-op‐
95 tion-config> results in the default being used for that portion respec‐
96 tively.
97 TCTI Defaults
99 When a TCTI is not specified, the default TCTI is searched for using
100 dlopen(3) semantics. The tools will search for tabrmd, device and
101 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
102 what TCTI will be chosen as the default by using the -v option to print
103 the version information. The “default-tcti” key-value pair will indi‐
104 cate which of the aforementioned TCTIs is the default.
105 Custom TCTIs
107 Any TCTI that implements the dynamic TCTI interface can be loaded. The
108 tools internally use dlopen(3), and the raw tcti-name value is used for
109 the lookup. Thus, this could be a path to the shared library, or a li‐
110 brary name as understood by dlopen(3) semantics.
111
113 This collection of options are used to configure the various known TCTI
114 modules available:
115 • device: For the device TCTI, the TPM character device file for use by
117 the device TCTI can be specified. The default is /dev/tpm0.
118 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
120 vice:/dev/tpm0”
121 • mssim: For the mssim TCTI, the domain name or IP address and port
123 number used by the simulator can be specified. The default are
124 127.0.0.1 and 2321.
125 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
127 TI=“mssim:host=localhost,port=2321”
128 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
130 ries of simple key value pairs separated by a `,' character. Each
131 key and value string are separated by a `=' character.
132 • TCTI abrmd supports two keys:
134 1. `bus_name' : The name of the tabrmd service on the bus (a
136 string).
137 2. `bus_type' : The type of the dbus instance (a string) limited to
139 `session' and `system'.
140 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
142 ample.FooBar:
143 \--tcti=tabrmd:bus_name=com.example.FooBar
145 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
147 sion:
148 \--tcti:bus_type=session
150 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
152 ules.
153
155 Start a policy session and restart it, unsealing some data.
156 # create a policy and bind it to an object
157 tpm2_startauthsession -S session.dat
158 tpm2_policypcr -S session.dat -l "sha1:0,1,2,3" -L policy.dat
160 tpm2_createprimary -c primary.ctx
162 tpm2_create -Cprimary.ctx -u key.pub -r key.priv -L policy.dat -i- <<< "secret"
164 tpm2_load -C primary.ctx -c key.ctx -u key.pub -r key.priv
166 tpm2_flushcontext session.dat
168 # satisfy the policy and use the object
170 tpm2_startauthsession --policy -S session.dat
171 tpm2_policypcr -S session.dat -l "sha1:0,1,2,3"
173 # PCR event occurs here causing unseal to fail
175 tpm2_pcrevent 0 <<< "event data"
176 tpm2_unseal -psession:session.dat -c key.ct
178 ERROR: Esys_Unseal(0x128) - tpm:error(2.0): PCR have changed since checked
179 # Clear the policy digest to initial state, note access to object no longer allowed by
181 # policy so policyor would be useful here.
182 tpm2_policyrestart -S session.dat
183
185 Tools can return any of the following codes:
186 • 0 - Success.
188 • 1 - General non-specific error.
190 • 2 - Options handling error.
192 • 3 - Authentication error.
194 • 4 - TCTI related error.
196 • 5 - Non supported scheme. Applicable to tpm2_testparams.
198
200 It expects a session to be already established via tpm2_startauthses‐
201 sion(1) and requires one of the following:
202 • direct device access
204 • extended session support with tpm2-abrmd.
206 Without it, most resource managers will not save session state between
208 command invocations.
209
211 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
212
214 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
215tpm2-tools tpm2_policyrestart(1)