tpm2_nvread

Section: General Commands Manual (1)
Updated: SEPTEMBER 2017
Page Index

NAME

tpm2_nvread(1) - Read the data stored in a Non-Volatile (NV)s index.

SYNOPSIS

tpm2_nvread [OPTIONS]

DESCRIPTION

tpm2_nvread(1) - Read the data stored in a Non-Volatile (NV)s index.

OPTIONS

•

-x, -index=NV_INDEX: Specifies the index to define the space at.

•

-a, -auth-handle=SECRET_DATA_FILE: specifies the handle used to authorize:

•: 0x40000001 for TPM_RH_OWNER
•: 0x4000000C for TPM_RH_PLATFORM

•

-f, -output=FILE: file to write data

•

-P, -handle-passwd=HANDLE_PASSWORD: specifies the password of authHandle. Passwords should follow the "password formatting standards, see section"Password Formatting“.

•

-s, -size=SIZE: Specifies the size of data to be read in bytes, starting from 0 if offset is not specified. If not specified, the size of the data as reported by the public portion of the index will be used.

•

-o, -offset=OFFSET: The offset within the NV index to start reading from.

•

-S, -input-session-handle=SIZE: Optional Input session handle from a policy session for authorization.

•

-L, -set-list==PCR_SELECTION_LIST:

: The list of pcr banks and selected PCRs' ids. PCR_SELECTION_LIST values should follow the pcr bank specifiers standards, see section "PCR Bank Specfiers".

•

-F,**-pcr-input-file=PCR_INPUT_FILE

: Optional Path or Name of the file containing expected pcr values for the specified index. Default is to read the current PCRs per the set list.

COMMON OPTIONS

This collection of options are common to many programs and provide information that many users may expect.

•: -h, -help: Display the tools manpage. This requires the manpages to be installed or on MANPATH, See man(1) for more details.
•: -v, -version: Display version information for this tool, supported tctis and exit.
•: -V, -verbose: Increase the information that the tool prints to the console during its execution. When using this option the file and line number are printed.
•: -Q, -quiet: Silence normal tool output to stdout.
•: -Z, -enable-errata: Enable the application of errata fixups. Useful if an errata fixup needs to be applied to commands sent to the TPM. # TCTI ENVIRONMENT

This collection of environment variables that may be used to configure the various TCTI modules available.

The values passed through these variables can be overridden on a per-command basis using the available command line options, see the TCTI_OPTIONS section.

The variables respected depend on how the software was configured.

•

TPM2TOOLS_TCTI_NAME: Select the TCTI used for communication with the next component down the TSS stack. In most configurations this will be the TPM but it could be a simulator or proxy. The current known TCTIs are:

•: tabrmd - The new resource manager, called tabrmd (https://github.com/01org/tpm2-abrmd).
•: socket - Typically used with the old resource manager, or talking directly to a simulator.
•: device - Used when talking directly to a TPM device file.

•

TPM2TOOLS_DEVICE_FILE: When using the device TCTI, specify the TPM device file. The default is "/dev/tpm0".

: Note: Using the tpm directly requires the users to ensure that concurrent access does not occur and that they manage the tpm resources. These tasks are usually managed by a resource manager. Linux 4.12 and greater supports an in kernel resource manager at "/dev/tpmrm", typically "/dev/tpmrm0".

•

TPM2TOOLS_SOCKET_ADDRESS: When using the socket TCTI, specify the domain name or IP address used. The default is 127.0.0.1.

•

TPM2TOOLS_SOCKET_PORT: When using the socket TCTI, specify the port number used. The default is 2321.

TCTI OPTIONS

This collection of options are used to configure the varous TCTI modules available. They override any environment variables.

•

-T, -tcti=TCTI_NAME[:TCTI_OPTIONS]: Select the TCTI used for communication with the next component down the TSS stack. In most configurations this will be the resource manager: tabrmd (https://github.com/01org/tpm2-abrmd) Optionally, tcti specific options can appended to TCTI_NAME by appending a : to TCTI_NAME.

•: For the device TCTI, the TPM device file for use by the device TCTI can be specified. The default is /dev/tpm0. Example: -T device:/dev/tpm0
•: For the socket TCTI, the domain name or IP address and port number used by the socket can be specified. The default are 127.0.0.1 and 2321. Example: -T socket:127.0.0.1:2321
•: For the abrmd TCTI, it takes no options. Example: -T abrmd

Password Formatting

Passwords are interpreted in two forms, string and hex-string. A string password is not interpreted, and is directly used for authorization. A hex-string, is converted from a hexidecimal form into a byte array form, thus allowing passwords with non-printable and/or terminal un-friendly characters.

By default passwords are assumed to be in the string form. Password form is specified with special prefix values, they are:

•: str: - Used to indicate it is a raw string. Useful for escaping a password that starts with the "hex:" prefix.
•: hex: - Used when specifying a password in hex string format.

EXAMPLES

To read 32 bytes from an index starting at offset 0:


tpm2_nvread -x 0x1500016 -a 0x40000001 -s 32

RETURNS

0 on success or 1 on failure.

BUGS

Github Issues (https://github.com/01org/tpm2-tools/issues)

HELP

See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)