swtpm(8) swtpm(8)
NAME
swtpm - TPM Emulator for TPM 1.2 and 2.0
SYNOPSIS
swtpm socket [OPTIONS]
swtpm chardev [OPTIONS]
swtpm cuse [OPTIONS]
DESCRIPTION
swtpm implements a TPM software emulator built on libtpms. It provides
access to TPM functionality over a TCP/IP socket interface or it can
listend for commands on a character device, or create a CUSE (character
device in userspace) interface for receiving of TPM commands.
Unless corresponding command line parameters are used, the swtpm socket
version requires that the environment variable TPM_PORT be set to the
TCP/IP port the process is supposed to listen on for TPM request
messages.
Similarly, the environment variable TPM_PATH can be set and contain the
name of a directory where the TPM can store its persistent state into.
The swtpm process can be gracefully terminated by sending a SIGTERM
signal to it.
The swtpm cuse version requires root rights to start the TPM.
Options for socket interface
The following options are supported if the socket interface is chosen:
-p|--port <port>
Use the given port rather than using the environment variable
TPM_PORT.
-t|--terminate
Terminate the TPM after the client has closed the connection.
--server [type=tcp][,port=<port>[,bindaddr=<address>
[,ifname=<ifname>]]][,fd=<fd>][,disconnect]
Expect TCP connections on the given port; if a port is not provided
a file descriptor must be passed with the fd parameter and the
commands are read from this file descriptor then. If a port is
provided the bind address on which to listen for TCP connections
can be provided as well; the default bind address is 127.0.0.1. If
a link local IPv6 address is provided, the name of the interface to
bind to must be provided with ifname.
This parameter enables a persistent connection by default unless
the disconnect option is given. This parameter should be used
rather than the -p and --fd options.
--server type=unixio[,path=<path>][,fd=<fd>]
[,mode=<0...>][,uid=<uid>][,gid=<gid>]
Expect UnixIO connections on the given path. If no path is
provided, a file descriptor must be passed instead. The mode
parameter allows a user to set the file mode bits of the UnixIO
path. The mode bits value must be given as an octal number starting
with a '0'. The default value is 0770. uid and gid set the
ownership of the UnixIO socket's path. This operation requires
root privileges.
Options for character device interface
The following options are supported if the chardev interface is chosen:
-c|--chardev <device path>
Use the given device to listen for TPM commands and send response
on.
--vtpm-proxy
Create a Linux vTPM proxy device instance and read TPM commands
from its backend device.
Options for the CUSE interface
The following options are supported if the cuse interface is chosen:
-n|--name <NAME>
The TPM will use a device with the given name. A device with the
given name will be created in /dev. This is a mandatory option.
-M|--maj <MAJOR>
Create the device with the given major number.
-m|--min <MINOR>
Create the device with the given minor number.
Options for socket and character device interfaces:
The following options are supported by the socket and character device
interfaces:
-f|--fd <fd>
Use the given socket file descriptor or character device file
descriptor for receiving TPM commands and sending responses. For
the socket interface, this option automatically assumes -t.
-d|--daemon
Daemonize the process.
--ctrl type=[unixio|tcp][,path=<path>]
[,port=<port>[,bindaddr=<address>[,ifname=<ifname>]]]
[,fd=<filedescriptor>|clientfd=<filedescriptor>]
[,mode=<0...>][,uid=<uid>][,gid=<gid>]
This option adds a control channel to the TPM. The control channel
can either use a UnixIO socket with a given path or filedescriptor
or it can use a TCP socket on the given port or filedescriptor. If
a port is provided the bind address on which to listen for TCP
connections can be provided as well; the default bind address is
127.0.0.1. If a link local IPv6 address is provided, the name of
the interface to bind to must be provided with ifname.
The mode parameter allows a user to set the file mode bits of the
UnixIO path. The mode bits value must be given as an octal number
starting with a '0'. The default value is 0770. uid and gid set
the ownership of the UnixIO socket's path. This operation requires
root privileges.
The control channel enables out-of-band control of the TPM, such as
resetting the TPM.
Options for all interfaces
The following options are support by all interfaces:
--tpmstate dir=<dir>[,mode=<0...>]|backend-uri=<uri>
Use the given path rather than using the environment variable
TPM_PATH.
If dir is specified, the TPM state files will be written to the dir
with the given file mode bits. This value must be given as an octal
number starting with a '0'. The default value is 0640.
If backend-uri is specified, the TPM state data will be stored to
the URI. Currently backend-uri=dir://<path_to_dir> and
backend-uri=file://<path_to_dir> are available. For 'dir://', the
URI should specify the path to the directory where files are
stored. If path_to_dir starts with a '/' then the path is
interpreted as an absolute path, otherwise it is a path relative to
the current directory. For 'file://', the URI should specify a
single file or block device where TPM state will be stored. A
blockdevice must exist already and be big enough to store all
state. (since v0.7)
--tpm2
Choose TPM 2 functionality; by default a TPM 1.2 is chosen.
--log [fd=<fd>|file=<path>][,level=<n>] [,prefix=<prefix>][,truncate]
Enable logging to a file given its file descriptor or its path. Use
'-' for path to suppress the logging.
The level parameter allows a user to choose the level of logging.
Starting at log level 5, libtpms debug logging is activated.
All logged lines will be prefixed with prefix. By default no prefix
is prepended.
If truncate is passed, the log file will be truncated.
--locality reject-locality-4[,allow-set-locality]
The reject-locality-4 parameter will cause TPM error messages to be
returned for requests to set the TPM into locality 4.
The allow-set-locality parameter allows the swtpm to receive
TPM/TPM2_SetLocality commands. This is parameter is useful if the
Linux VTPM proxy driver access is enabled by file descriptor
passing. This option is implied by the --vtpm-proxy option and
therefore need not be explicitly set if this option is passed. In
all other cases care should be taken as to who can send the
TPM/TPM2_SetLocality command.
--key file=<keyfile>|fd=<fd>
[,format=<hex|binary>][,mode=aes-cbc|aes-256-cbc],
[remove[=true|false]]
Enable encryption of the state files of the TPM. The keyfile must
contain an AES key of supported size; 128 bit (16 bytes) and 256
bit (32 bytes) keys are supported.
The key may be in binary format, in which case the file size must
be 16 or 32 bytes. If the key is in hex format (default), the key
may consist of 32 or 64 hex digits starting with an optional '0x'.
The mode parameter indicates which block chaining mode is to be
used. Currently aes-cbc (aes-128-cbc) and aes-256-cbc are
supported. The encrypted data is integrity protected using
encrypt-then-mac.
The remove parameter will attempt to remove the given keyfile once
the key has been read.
--key pwdfile=<passphrase file>|pwdfd=<fd>
[,mode=aes-cbc|aes-256-cbc][remove[=true|false]][,kdf=sha512|pbkdf2]
This variant of the key parameter allows a user to provide a
passphrase in a file. The file is read and a key is derived from
it using either a SHA512 hash or PBKDF2. By default PBKDF2 is used.
--migration-key file=<keyfile>|fd=<fd>
[,format=<hex|binary>][,mode=aes-cbc|aes-256-cbc]
[,remove[=true|false]]
The availability of a migration key ensures that the state of the
TPM will not be revealed in unencrypted form when the TPM state
blobs are retrieved through the ioctl interface. The migration key
is not used for encrypting TPM state written to files, this is what
the --key parameter is used for.
The migration key and the key used for encrypting the TPM state
files may be the same.
While the key for the TPM state files needs to stay with those
files it encrypts, the migration key needs to stay with the TPM
state blobs. If for example the state of the TPM is migrated
between hosts in a data center, then the TPM migration key must be
available at all the destinations, so in effect it may have to be a
key shared across all machines in the datacenter. In contrast to
that, the key used for encrypting the TPM state files can be
different for each TPM and need only be available on the host where
the TPM state resides.
The migration key enables the encryption of the TPM state blobs.
The keyfile must contain an AES key of supported size; 128 bit (16
bytes) and 256 bit (32 bytes) keys are supported.
The key may be in binary format, in which case the file size must
be 16 or 32 bytes. If the key is in hex format (default), the key
may consist of 32 or 64 hex digits starting with an optional '0x'.
The mode parameter indicates which block chaining mode is to be
used. Currently aes-cbc (aes-128-cbc) and aes-256-cbc are
supported. The encrypted data is integrity protected using
encrypt-then-mac.
The remove parameter will attempt to remove the given keyfile once
the key has been read.
--migration-key pwdfile=<passphrase file>|pwdfd=<fd>
[,mode=aes-cbc|aes-256-cbc][,remove[=true|false]][,pdf=sha512|pbkdf2]
This variant of the key parameter allows a user to provide a
passphrase in a file. The file is read and a key is derived from
it using either a SHA512 hash or PBKDF2. By default PBKDF2 is used.
--pid file=<pidfile>|fd=<filedescriptor>
This options allows a user to set the name of file where the
process ID (pid) of the TPM will be written into. It is also
possible to pass a file descriptor to a file that has been opened
for writing.
-r|--runas <owner>
Switch to the given user. This option can only be used when swtpm
is started as root.
--seccomp action=none|log|kill (since v0.2)
This option allows a user to select the action to take by the
seccomp profile when a syscall is executed that is not allowed. The
default is kill. To disable the seccomp profile, choose none. The
log action logs offending syscalls. The log action is only
available if libseccomp supports logging.
This option is only available on Linux and only if swtpm was
compiled with libseccomp support.
--flags [not-need-init]
[,startup-clear|startup-state|startup-deactivated|startup-none]
The not-need-init flag enables the TPM to accept TPM commands right
after start without requiring an INIT to be sent to it through the
command channel (see the '-i' option of swtpm_ioctl).
The startup options cause a TPM_Startup or TPM2_Startup command to
automatically be sent. The startup-deactivated option is only valid
for a TPM 1.2. These options imply not-need-init, except for the
startup-none option, which results in no command being sent.
If --vtpm-proxy is used, startup-clear is automatically chosen but
this can be changed with this option.
--print-capabilities (since v0.2)
Print capabilities that were added to swtpm after version 0.1. The
output may contain the following:
{
"type": "swtpm",
"features": [
"tpm-1.2",
"tpm-2.0",
"cmdarg-seccomp",
"cmdarg-key-fd",
"cmdarg-pwd-fd",
"cmdarg-print-states",
"nvram-backend-dir",
"nvram-backend-file",
"tpm-send-command-header",
"flags-opt-startup",
"rsa-keysize-1024",
"rsa-keysize-2048",
"rsa-keysize-3072"
],
"version": "0.7.0"
}
The version field is available since v0.7.
The meaning of the feature verbs is as follows:
tpm-1.2 (since v0.7)
TPM 1.2 emulation is supported (libtpms is compiled with 1.2
support).
tpm-2.0 (since v0.7)
TPM 2 emulation is supported (libtpms is compiled with 2.0
support).
(the --tpm2 option is supported)
cmdarg-seccomp (since v0.2)
The --seccomp option is supported.
cmdarg-key-fd (since v0.2)
The --key option supports the fd= parameter.
cmdarg-pwd-fd (since v0.2)
The --key option supports the pwdfd= parameter.
cmdarg-print-states (since v0.7)
The --print-states option is supported.
nvram-backend-dir (since v0.7)
The --tpmstate option supports the backend-uri=dir://...
parameter.
nvram-backend-file (since v0.7)
The --tpmstate option supports the backend-uri=file://...
parameter.
tpm-send-command-header (since v0.2)
The TPM 2 commands may be prefixed by a header that carries a
4-byte command, 1 byte for locality, and 4-byte TPM 2 command
length indicator. The TPM 2 will respond by preprending a
4-byte response indicator and a 4-byte trailer. All data is
sent in big endian format.
flags-opt-startup (since v0.3)
The --flags option supports the startup-... options.
rsa-keysize-2048 (since v0.4)
The TPM 2 supports the shown RSA key sizes. If none of the rsa-
keysize verbs is shown then only RSA 2048 bit keys are
supported.
--print-states (since v0.7)
This option allows to print out the TPM 1.2 or TPM 2 state blobs
that are currently stored in a storage backend. This option
requires that the storage backend be specified using the --tpmstate
option and if TPM 2 state blobs are supposed to be shown, the
--tpm2 option must be passed.
The following shows the JSON output of this option. It indicates
that the 'permall' and 'volatile' states are available.
{
"type": "swtpm",
"states": [
{
"name": "permall",
"size": 6013
}, {
"name": "volatile",
"size": 1087
}
]
}
-h|--help
Display usage info.
SEE ALSO
swtpm_bios, swtpm_cuse
swtpm 2023-05-18 swtpm(8)
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