=head1 NAME

swtpm - TPM Emulator for TPM 1.2 and 2.0

=head1 SYNOPSIS

B<swtpm socket [OPTIONS]>

B<swtpm chardev [OPTIONS]>

B<swtpm cuse [OPTIONS]>

=head1 DESCRIPTION

B<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
B<swtpm> socket version requires that the environment variable I<TPM_PORT>
be set to the TCP/IP port the process is supposed to listen on for TPM
request messages. 

Similarly, the environment variable I<TPM_PATH> can be set and
contain the name of a directory where the TPM can store its persistent
state into.

The B<swtpm> process can be gracefully terminated by sending a
I<SIGTERM> signal to it.

The B<swtpm> cuse version requires root rights to start the TPM.

=head1 Options for socket interface

The following options are supported if the I<socket> interface is chosen:

=over 4

=item B<-p|--port <port>>

Use the given port rather than using the environment variable TPM_PORT.

=item B<-t|--terminate>

Terminate the TPM after the client has closed the data channel connection
(TCP only).

=item B<--server [type=tcp][,port=E<lt>portE<gt>[,bindaddr=E<lt>addressE<gt> [,ifname=E<lt>ifnameE<gt>]]][,fd=E<lt>fdE<gt>][,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 I<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 I<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.

=item B<--server type=unixio[,path=E<lt>pathE<gt>][,fd=E<lt>fdE<gt>] [,mode=E<lt>0...E<gt>][,uid=E<lt>uidE<gt>][,gid=E<lt>gidE<gt>]>

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.

=back


=head1 Options for character device interface

The following options are supported if the I<chardev> interface is chosen:

=over 4

=item B<-c|--chardev <device path>>

Use the given device to listen for TPM commands and send response on.

=item B<--vtpm-proxy>

Create a Linux vTPM proxy device instance and read TPM commands from its
backend device.

=back


=head1 Options for the CUSE interface

The following options are supported if the I<cuse> interface is chosen:

=over 4

=item B<-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.

=item B<-M|--maj <MAJOR>>

Create the device with the given major number.

=item B<-m|--min <MINOR>>

Create the device with the given minor number.

=back


=head1 Options for socket and character device interfaces:

The following options are supported by the socket and character device interfaces:

=over 4

=item B<-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.

=item B<-d|--daemon>

Daemonize the process.

=item B<--ctrl type=[unixio|tcp][,path=E<lt>pathE<gt>] [,port=E<lt>portE<gt>[,bindaddr=E<lt>addressE<gt>[,ifname=E<lt>ifnameE<gt>]]] [,fd=E<lt>filedescriptorE<gt>|clientfd=E<lt>filedescriptorE<gt>] [,mode=E<lt>0...E<gt>][,uid=E<lt>uidE<gt>][,gid=E<lt>gidE<gt>][,terminate] >

This option adds a control channel to the TPM. The control channel can either use a UnixIO socket with
a given I<path> or I<filedescriptor> or it can use a TCP socket on the given I<port> or I<filedescriptor>.
If a port is provided the I<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 I<ifname>.

The I<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. I<uid> and I<gid> set the ownership of the UnixIO socket's path.
This operation requires root privileges.

The I<terminate> parameter enables the automatic termination of swtpm when the
control channel connection has been lost. This is useful in scenarios where
the control channel connection is held permanently, such as by QEMU, and
swtpm should terminate upon abnormal termination of the client that could
not send a CMD_SHUTDOWN via the control channel anymore.

The control channel enables out-of-band control of the TPM, such as resetting the TPM.

=back


=head1 Options for all interfaces

The following options are support by all interfaces:

=over 4

=item B<--tpmstate dir=E<lt>dirE<gt>[,mode=E<lt>0...E<gt>]|backend-uri=E<lt>uriE<gt>>

Use the given path rather than using the environment variable TPM_PATH.

If I<dir> is specified, the TPM state files will be written to the I<dir> with
the given file I<mode> bits. This value must be given as an octal number starting with a '0'.
The default value is 0640.

If I<backend-uri> is specified, the TPM state data will be stored to the URI.
Currently I<backend-uri=dir://<path_to_dir>> and I<backend-uri=file://<path_to_dir>>
are available. For 'dir://', the URI should specify the path to the directory where
files are stored. If I<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)

=item B<--tpm2>

Choose TPM 2 functionality; by default a TPM 1.2 is chosen.

=item B<--log [fd=E<lt>fdE<gt>|file=E<lt>pathE<gt>][,level=E<lt>nE<gt>] [,prefix=E<lt>prefixE<gt>][,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 I<truncate> is passed, the log file will be truncated.

=item B<--locality reject-locality-4[,allow-set-locality]>

The I<reject-locality-4> parameter will cause TPM error messages to be
returned for requests to set the TPM into locality 4.

The I<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 I<--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.

=item B<--key file=E<lt>keyfileE<gt>|fd=E<lt>fdE<gt> [,format=E<lt>hex|binaryE<gt>][,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 I<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 I<remove> parameter will attempt to remove the given keyfile once the key
has been read.

=item B<--key pwdfile=E<lt>passphrase fileE<gt>|pwdfd=E<lt>fdE<gt> [,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.

=item B<--migration-key file=E<lt>keyfileE<gt>|fd=E<lt>fdE<gt> [,format=E<lt>hex|binaryE<gt>][,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 I<--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 B<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 I<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 I<remove> parameter will attempt to remove the given keyfile once the key
has been read.

=item B<--migration-key pwdfile=E<lt>passphrase fileE<gt>|pwdfd=E<lt>fdE<gt> [,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.

=item B<--pid file=E<lt>pidfileE<gt>|fd=E<lt>filedescriptorE<gt>>

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.

=item B<-r|--runas E<lt>ownerE<gt>>

Switch to the given user. This option can only be used when swtpm is started as root.

=item B<-R|--chroot E<lt>path<gt>>

Chroot to the given directory at startup. This option can only be used when swtpm is
started as root.

=item B<--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 I<kill>. To disable
the seccomp profile, choose I<none>. The I<log> action logs offending syscalls.
The I<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.

=item B<--flags [not-need-init][,startup-clear|startup-state|startup-deactivated|startup-none][,disable-auto-shutdown]>

The I<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 I<startup> options cause a TPM_Startup or TPM2_Startup command to
automatically be sent. The I<startup-deactivated> option is only valid for
a TPM 1.2. These options imply I<not-need-init>, except for the
I<startup-none> option, which results in no command being sent.

If I<--vtpm-proxy> is used, I<startup-clear> is automatically chosen but
this can be changed with this option.

The I<disable-auto-shutdown> flag prevents swtpm from automatically sending a
TPM2_Shutdown() before the reset of a TPM 2 or before the swtpm process
is terminated. When this flag is not provide swtpm will send this command to
avoid increasing the dictionary attack (DA) lockout counter and ulimately
a DA lockout by the TPM 2 due to omission of sending a required TPM2_Shutdown()
before TPM 2 reset or swtpm process termination.

=item B<--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",
        "cmdarg-chroot",
        "cmdarg-migration",
        "nvram-backend-dir",
        "nvram-backend-file",
        "tpm-send-command-header",
        "flags-opt-startup",
        "flags-opt-disable-auto-shutdown",
        "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:

=over 4

=item B<tpm-1.2> (since v0.7)

TPM 1.2 emulation is supported (libtpms is compiled with 1.2 support).

=item B<tpm-2.0> (since v0.7)

TPM 2 emulation is supported (libtpms is compiled with 2.0 support).

(the I<--tpm2> option is supported)

=item B<cmdarg-seccomp> (since v0.2)

The I<--seccomp> option is supported.

=item B<cmdarg-key-fd> (since v0.2)

The I<--key> option supports the I<fd=> parameter.

=item B<cmdarg-pwd-fd> (since v0.2)

The I<--key> option supports the I<pwdfd=> parameter.

=item B<cmdarg-print-states> (since v0.7)

The I<--print-states> option is supported.

=item B<cmdarg-chroot> (since v0.8)

The I<--chroot> option is supported.

=item B<cmdarg-migration> (since v0.8)

The I<--migration> option is supported.

=item B<nvram-backend-dir> (since v0.7)

The I<--tpmstate> option supports the I<backend-uri=dir://...>
parameter.

=item B<nvram-backend-file> (since v0.7)

The I<--tpmstate> option supports the I<backend-uri=file://...>
parameter.

=item B<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.

=item B<flags-opt-startup> (since v0.3)

The I<--flags> option supports the I<startup-...> options.

=item B<flags-opt-disable-auto-shutdown> (since v0.8)

The I<--flags> option supports the I<disable-auto-shutdown> flag.

=item B<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.

=back

=item B<--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 I<--tpmstate> option
and if TPM 2 state blobs are supposed to be shown, the I<--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
        }
      ]
    }

=item B<--migration [incoming][,release-lock-outgoing]>

This option allows to control the locking of the NVRAM storage
for the purpose of supporting migration between hosts that have
shared storage setup for the swtpm's state directory and if
locking is supported by the storage backend. The directory storage
backend for example supports locking and therefore requires usage
of this option in case of shared storage.
When providing the I<incoming> option parameter swtpm defers the
locking of the NVRAM until the state blobs are received or until the
first TPM command is processed if no state blobs were received.
The I<release-lock-outgoing> option parameter causes swtpm to
release any NVRAM lock once the TPM's 'savestate' blob is received
from swtpm. To avoid releasing the lock too early the 'permanent'
and 'volatile' state blobs must be received before the 'savestate'
blob.

=item B<-h|--help>

Display usage info.

=back

=head1 NOTES

If a TPM 2 is used, the user is typically required to send a TPM2_Shutdown()
command to a TPM 2 to avoid possibly increasing the TPM_PT_LOCKOUT_COUNTER
that may lead to a dictionary attack (DA) lockout upon next startup
(TPM2_Startup()) of the TPM 2. Whether the TPM_PT_LOCKOUT_COUNTER is
increased depends on previous commands sent to the TPM 2 as well as
internal state of the TPM 2. One example that will trigger the counter to
increase is the omission of a password when trying to access a
password-protected object or NVRAM location that has the DA attribute set,
followed by termination of swtpm without sending TPM2_Shutdown(). To avoid
a DA lockout swtpm will make a best-effort and send a TPM2_Shutdown(SU_STATE)
or TPM2_Shutdown(SU_CLEAR) if found necessary.

=head1 SEE ALSO

B<swtpm_bios>, B<swtpm_cuse>