geom/eli/geli.8

.\" Copyright (c) 2005-2019 Pawel Jakub Dawidek <pawel@dawidek.net>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd April 24, 2024
.Dt GELI 8
.Os
.Sh NAME
.Nm geli
.Nd "control utility for the cryptographic GEOM class"
.Sh SYNOPSIS
To compile GEOM_ELI into your kernel, add the following lines to your kernel
configuration file:
.Bd -ragged -offset indent
.Cd "device crypto"
.Cd "options GEOM_ELI"
.Ed
.Pp
Alternatively, to load the GEOM_ELI module at boot time, add the following line
to your
.Xr loader.conf 5 :
.Bd -literal -offset indent
geom_eli_load="YES"
.Ed
.Pp
.No Usage of the Nm
utility:
.Pp
.Nm
.Cm init
.Op Fl bdgPRTv
.Op Fl a Ar aalgo
.Op Fl B Ar backupfile
.Op Fl e Ar ealgo
.Op Fl i Ar iterations
.Op Fl J Ar newpassfile
.Op Fl K Ar newkeyfile
.Op Fl l Ar keylen
.Op Fl s Ar sectorsize
.Op Fl V Ar version
.Ar prov ...
.Nm
.Cm label - an alias for
.Cm init
.Nm
.Cm attach
.Op Fl Cdprv
.Op Fl n Ar keyno
.Op Fl j Ar passfile
.Op Fl k Ar keyfile
.Ar prov ...
.Nm
.Cm detach
.Op Fl fl
.Ar prov ...
.Nm
.Cm stop - an alias for
.Cm detach
.Nm
.Cm onetime
.Op Fl dRT
.Op Fl a Ar aalgo
.Op Fl e Ar ealgo
.Op Fl l Ar keylen
.Op Fl s Ar sectorsize
.Ar prov
.Nm
.Cm configure
.Op Fl bBdDgGrRtT
.Ar prov ...
.Nm
.Cm setkey
.Op Fl pPv
.Op Fl i Ar iterations
.Op Fl j Ar passfile
.Op Fl J Ar newpassfile
.Op Fl k Ar keyfile
.Op Fl K Ar newkeyfile
.Op Fl n Ar keyno
.Ar prov
.Nm
.Cm delkey
.Op Fl afv
.Op Fl n Ar keyno
.Ar prov
.Nm
.Cm kill
.Op Fl av
.Op Ar prov ...
.Nm
.Cm backup
.Op Fl v
.Ar prov
.Ar file
.Nm
.Cm restore
.Op Fl fv
.Ar file
.Ar prov
.Nm
.Cm suspend
.Op Fl v
.Fl a | Ar prov ...
.Nm
.Cm resume
.Op Fl pv
.Op Fl j Ar passfile
.Op Fl k Ar keyfile
.Ar prov
.Nm
.Cm resize
.Op Fl v
.Fl s Ar oldsize
.Ar prov
.Nm
.Cm version
.Op Ar prov ...
.Nm
.Cm clear
.Op Fl v
.Ar prov ...
.Nm
.Cm dump
.Op Fl v
.Ar prov ...
.Nm
.Cm list
.Nm
.Cm status
.Nm
.Cm load
.Nm
.Cm unload
.Sh DESCRIPTION
The
.Nm
utility is used to configure encryption on GEOM providers.
.Pp
The following is a list of the most important features:
.Pp
.Bl -bullet -offset indent -compact
.It
Utilizes the
.Xr crypto 9
framework, so when there is crypto hardware available,
.Nm
will make use of it automatically.
.It
Supports many cryptographic algorithms (currently
.Nm AES-XTS ,
.Nm AES-CBC ,
and
.Nm Camellia-CBC ) .
.It
Can optionally perform data authentication (integrity verification) utilizing
one of the following algorithms:
.Nm HMAC/SHA1 ,
.Nm HMAC/RIPEMD160 ,
.Nm HMAC/SHA256 ,
.Nm HMAC/SHA384
or
.Nm HMAC/SHA512 .
.It
Can create a User Key from up to two, piecewise components: a passphrase
entered via prompt or read from one or more passfiles; a keyfile read from
one or more files.
.It
Allows encryption of the root partition.
The user is asked for the passphrase before the root filesystem is mounted.
.It
Strengthens the passphrase component of the User Key with:
.Rs
.%A B. Kaliski
.%T "PKCS #5: Password-Based Cryptography Specification, Version 2.0."
.%R RFC
.%N 2898
.Re
.It
Allows the use of two independent User Keys (e.g., a
.Qq "user key"
and a
.Qq "company key" ) .
.It
It is fast -
.Nm
performs simple sector-to-sector encryption.
.It
Allows the encrypted Master Key to be backed up and restored,
so that if a user has to quickly destroy key material,
it is possible to get the data back by restoring keys from
backup.
.It
Providers can be configured to automatically detach on last close,
so users do not have to remember to detach providers after unmounting
the filesystems.
.It
Allows attaching a provider with a random, one-time Master Key,
which is useful for swap partitions and temporary filesystems.
.It
Allows verification of data integrity (data authentication).
.It
Allows suspending and resuming encrypted devices.
.El
.Pp
The first argument to
.Nm
indicates an action to be performed:
.Bl -tag -width ".Cm configure"
.It Cm init
Initialize providers which need to be encrypted.
If multiple providers are listed as arguments, they will all be initialized
with the same passphrase and/or User Key.
A unique salt will be randomly generated for each provider to ensure the
Master Key for each is unique.
Here you can set up the cryptographic algorithm to use, Data Key length,
etc.
The last sector of the providers is used to store metadata.
The
.Cm init
subcommand also automatically writes metadata backups to
.Pa /var/backups/<prov>.eli
file.
The metadata can be recovered with the
.Cm restore
subcommand described below.
.Pp
Additional options include:
.Bl -tag -width ".Fl J Ar newpassfile"
.It Fl a Ar aalgo
Enable data integrity verification (authentication) using the given algorithm.
This will reduce the size of storage available and also reduce speed.
For example, when using 4096 bytes sector and
.Nm HMAC/SHA256
algorithm, 89% of the original provider storage will be available for use.
Currently supported algorithms are:
.Nm HMAC/SHA1 ,
.Nm HMAC/RIPEMD160 ,
.Nm HMAC/SHA256 ,
.Nm HMAC/SHA384
and
.Nm HMAC/SHA512 .
If the option is not given, there will be no authentication, only encryption.
The recommended algorithm is
.Nm HMAC/SHA256 .
.It Fl b
Try to decrypt this partition during boot, before the root partition is mounted.
This makes it possible to use an encrypted root partition.
One will still need bootable unencrypted storage with a
.Pa /boot/
directory, which can be a CD-ROM disc or USB pen-drive, that can be removed
after boot.
.It Fl B Ar backupfile
File name to use for metadata backup instead of the default
.Pa /var/backups/<prov>.eli .
To inhibit backups, you can use
.Pa none
as the
.Ar backupfile .
If multiple providers were initialized in the one command, you can use
.Pa PROV
(all upper-case) in the file name, and it will be replaced with the provider
name.
If
.Pa PROV
is not found in the file name and multiple providers were initialized in the
one command,
.Pa -<prov>
will be appended to the end of the file name specified.
.It Fl d
When entering the passphrase to boot from this encrypted root filesystem, echo
.Ql *
characters.
This makes the length of the passphrase visible.
.It Fl e Ar ealgo
Encryption algorithm to use.
Currently supported algorithms are:
.Nm AES-XTS ,
.Nm AES-CBC ,
.Nm Camellia-CBC ,
and
.Nm NULL .
The default and recommended algorithm is
.Nm AES-XTS .
.Nm NULL
is unencrypted.
.It Fl g
Enable booting from this encrypted root filesystem.
The boot loader prompts for the passphrase and loads
.Xr loader 8
from the encrypted partition.
.It Fl i Ar iterations
Number of iterations to use with PKCS#5v2 when processing User Key
passphrase component.
If this option is not specified,
.Nm
will find the number of iterations which is equal to 2 seconds of crypto work.
If 0 is given, PKCS#5v2 will not be used.
PKCS#5v2 processing is performed once, after all parts of the passphrase
component have been read.
.It Fl J Ar newpassfile
Specifies a file which contains the passphrase component of the User Key
(or part of it).
If
.Ar newpassfile
is given as -, standard input will be used.
Only the first line (excluding new-line character) is taken from the given file.
This argument can be specified multiple times, which has the effect of
reassembling a single passphrase split across multiple files.
Cannot be combined with the
.Fl P
option.
.It Fl K Ar newkeyfile
Specifies a file which contains the keyfile component of the User Key
(or part of it).
If
.Ar newkeyfile
is given as -, standard input will be used.
This argument can be specified multiple times, which has the effect of
reassembling a single keyfile split across multiple keyfile parts.
.It Fl l Ar keylen
Data Key length to use with the given cryptographic algorithm.
If the length is not specified, the selected algorithm uses its
.Em default
key length.
.Bl -ohang -offset indent
.It Nm AES-XTS
.Em 128 ,
256
.It Nm AES-CBC , Nm Camellia-CBC
.Em 128 ,
192,
256
.El
.It Fl P
Do not use a passphrase as a component of the User Key.
Cannot be combined with the
.Fl J
option.
.It Fl s Ar sectorsize
Change decrypted provider's sector size.
Increasing the sector size allows increased performance,
because encryption/decryption which requires an initialization vector
is done per sector; fewer sectors means less computational work.
.It Fl R
Turn off automatic expansion.
By default, if the underlying provider grows, the encrypted provider will
grow automatically too.
The metadata will be moved to the new location.
If automatic expansion if turned off and the underlying provider changes
size, attaching encrypted provider will no longer be possible as the metadata
will no longer be located in the last sector.
In this case
.Nm GELI
will only log the previous size of the underlying provider, so metadata can
be found easier, if resize was done by mistake.
.It Fl T
Don't pass through
.Dv BIO_DELETE
calls (i.e., TRIM/UNMAP).
This can prevent an attacker from knowing how much space you're actually
using and which sectors contain live data, but will also prevent the
backing store (SSD, etc) from reclaiming space you're not using, which
may degrade its performance and lifespan.
The underlying provider may or may not actually obliterate the deleted
sectors when TRIM is enabled, so it should not be considered to add any
security.
.It Fl V Ar version
Metadata version to use.
This option is helpful when creating a provider that may be used by older
.Nm FreeBSD/GELI
versions.
Consult the
.Sx HISTORY
section to find which metadata version is supported by which
.Fx
version.
Note that using an older version of metadata may limit the number of
features available.
.El
.It Cm attach
Attach the given providers.
The encrypted Master Keys are loaded from the metadata and decrypted
using the given passphrase/keyfile and new GEOM providers are created
using the specified provider names.
A
.Qq .eli
suffix is added to the user specified provider names.
Multiple providers can only be attached with a single
.Cm attach
command if they all have the same passphrase and keyfiles.
.Pp
Additional options include:
.Bl -tag -width ".Fl j Ar passfile"
.It Fl C
Do a dry-run decryption.
This is useful to verify passphrase and keyfile without decrypting the device.
.It Fl d
If specified, the decrypted providers are detached automatically on last close,
so the user does not have to remember to detach
providers after unmounting the filesystems.
This only works when providers were opened for writing, and will not work if
the filesystems on the providers were mounted read-only.
Probably a better choice is the
.Fl l
option for the
.Cm detach
subcommand.
.It Fl n Ar keyno
Specifies the index number of the Master Key copy to use (could be 0 or 1).
If the index number is not provided all keys will be tested.
.It Fl j Ar passfile
Specifies a file which contains the passphrase component of the User Key
(or part of it).
For more information see the description of the
.Fl J
option for the
.Cm init
subcommand.
The same passfiles are used for all listed providers.
.It Fl k Ar keyfile
Specifies a file which contains the keyfile component of the User Key
(or part of it).
For more information see the description of the
.Fl K
option for the
.Cm init
subcommand.
The same keyfiles are used for all listed providers.
.It Fl p
Do not use a passphrase as a component of the User Keys.
Cannot be combined with the
.Fl j
option.
.It Fl r
Attach read-only providers.
They are not opened for writing.
.El
.It Cm detach
Detach the given providers, which means remove the devfs entry
and clear the Master Key and Data Keys from memory.
.Pp
Additional options include:
.Bl -tag -width ".Fl f"
.It Fl f
Force detach - detach even if the provider is open.
.It Fl l
Mark provider to detach on last close, after the last filesystem has been
unmounted.
If this option is specified, the provider will not be detached
while it is open, but will be automatically detached when it is closed for the
last time even if it was only opened for reading.
.El
.It Cm onetime
Attach the given providers with a random, one-time (ephemeral) Master Key.
The command can be used to encrypt swap partitions or temporary filesystems.
.Pp
Additional options include:
.Bl -tag -width ".Fl a Ar sectorsize"
.It Fl a Ar aalgo
Enable data integrity verification (authentication).
For more information, see the description of the
.Cm init
subcommand.
.It Fl e Ar ealgo
Encryption algorithm to use.
For more information, see the description of the
.Cm init
subcommand.
.It Fl d
Detach on last close, after the last filesystem has been unmounted.
Note: this option is not usable for temporary filesystems as the provider is
detached after the filesystem has been created.
It still can, and should, be used for swap partitions.
For more information, see the description of the
.Cm attach
subcommand.
.It Fl l Ar keylen
Data Key length to use with the given cryptographic algorithm.
For more information, see the description of the
.Cm init
subcommand.
.It Fl s Ar sectorsize
Change decrypted provider's sector size.
For more information, see the description of the
.Cm init
subcommand.
.It Fl R
Turn off automatic expansion.
For more information, see the description of the
.Cm init
subcommand.
.It Fl T
Disable TRIM/UNMAP passthru.
For more information, see the description of the
.Cm init
subcommand.
.El
.It Cm configure
Change configuration of the given providers.
.Pp
Additional options include:
.Bl -tag -width ".Fl b"
.It Fl b
Set the BOOT flag on the given providers.
For more information, see the description of the
.Cm init
subcommand.
.It Fl B
Remove the BOOT flag from the given providers.
.It Fl d
When entering the passphrase to boot from this encrypted root filesystem, echo
.Ql *
characters.
This makes the length of the passphrase visible.
.It Fl D
Disable echoing of any characters when a passphrase is entered to boot from this
encrypted root filesystem.
This hides the passphrase length.
.It Fl g
Enable booting from this encrypted root filesystem.
The boot loader prompts for the passphrase and loads
.Xr loader 8
from the encrypted partition.
.It Fl G
Deactivate booting from this encrypted root partition.
.It Fl r
Turn on automatic expansion.
For more information, see the description of the
.Cm init
subcommand.
.It Fl R
Turn off automatic expansion.
.It Fl t
Enable TRIM/UNMAP passthru.
For more information, see the description of the
.Cm init
subcommand.
.It Fl T
Disable TRIM/UNMAP passthru.
.El
.It Cm setkey
Install a copy of the Master Key into the selected slot, encrypted with
a new User Key.
If the selected slot is populated, replace the existing copy.
A provider has one Master Key, which can be stored in one or both slots,
each encrypted with an independent User Key.
With the
.Cm init
subcommand, only key number 0 is initialized.
The User Key can be changed at any time: for an attached provider,
for a detached provider, or on the backup file.
When a provider is attached, the user does not have to provide
an existing passphrase/keyfile.
.Pp
Additional options include:
.Bl -tag -width ".Fl J Ar newpassfile"
.It Fl i Ar iterations
Number of iterations to use with PKCS#5v2.
If 0 is given, PKCS#5v2 will not be used.
To be able to use this option with the
.Cm setkey
subcommand, only one key has to be defined and this key must be changed.
.It Fl j Ar passfile
Specifies a file which contains the passphrase component of a current User Key
(or part of it).
.It Fl J Ar newpassfile
Specifies a file which contains the passphrase component of the new User Key
(or part of it).
.It Fl k Ar keyfile
Specifies a file which contains the keyfile component of a current User Key
(or part of it).
.It Fl K Ar newkeyfile
Specifies a file which contains the keyfile component of the new User Key
(or part of it).
.It Fl n Ar keyno
Specifies the index number of the Master Key copy to change (could be 0 or 1).
If the provider is attached and no key number is given, the key
used for attaching the provider will be changed.
If the provider is detached (or we are operating on a backup file)
and no key number is given, the first Master Key copy to be successfully
decrypted with the provided User Key passphrase/keyfile will be changed.
.It Fl p
Do not use a passphrase as a component of the current User Key.
Cannot be combined with the
.Fl j
option.
.It Fl P
Do not use a passphrase as a component of the new User Key.
Cannot be combined with the
.Fl J
option.
.El
.It Cm delkey
Destroy (overwrite with random data) the selected Master Key copy.
If one is destroying keys for an attached provider, the provider
will not be detached even if all copies of the Master Key are destroyed.
It can even be rescued with the
.Cm setkey
subcommand because the Master Key is still in memory.
.Pp
Additional options include:
.Bl -tag -width ".Fl a Ar keyno"
.It Fl a
Destroy all copies of the Master Key (does not need
.Fl f
option).
.It Fl f
Force key destruction.
This option is needed to destroy the last copy of the Master Key.
.It Fl n Ar keyno
Specifies the index number of the Master Key copy.
If the provider is attached and no key number is given, the key
used for attaching the provider will be destroyed.
If provider is detached (or we are operating on a backup file) the key number
has to be given.
.El
.It Cm kill
This command should be used only in emergency situations.
It will destroy all copies of the Master Key on a given provider and will
detach it forcibly (if it is attached).
This is absolutely a one-way command - if you do not have a metadata
backup, your data is gone for good.
In case the provider was attached with the
.Fl r
flag, the keys will not be destroyed, only the provider will be detached.
.Pp
Additional options include:
.Bl -tag -width ".Fl a"
.It Fl a
If specified, all currently attached providers will be killed.
.El
.It Cm backup
Backup metadata from the given provider to the given file.
.It Cm restore
Restore metadata from the given file to the given provider.
.Pp
Additional options include:
.Bl -tag -width ".Fl f"
.It Fl f
Metadata contains the size of the provider to ensure that the correct
partition or slice is attached.
If an attempt is made to restore metadata to a provider that has a different
size,
.Nm
will refuse to restore the data unless the
.Fl f
switch is used.
If the partition or slice has been grown, the
.Cm resize
subcommand should be used rather than attempting to relocate the metadata
through
.Cm backup
and
.Cm restore .
.El
.It Cm suspend
Suspend device by waiting for all inflight requests to finish, clearing all
sensitive information such as the Master Key and Data Keys from kernel memory,
and blocking all further I/O requests until the
.Cm resume
subcommand is executed.
This functionality is useful for laptops.
Suspending a laptop should not leave an encrypted device attached.
The
.Cm suspend
subcommand can be used rather than closing all files and directories from
filesystems on the encrypted device, unmounting the filesystem, and
detaching the device.
Any access to the encrypted device will be blocked until the Master Key is
reloaded through the
.Cm resume
subcommand.
Thus there is no need to close nor unmount anything.
The
.Cm suspend
subcommand does not work with devices created with the
.Cm onetime
subcommand.
Please note that sensitive data might still be present in memory locations
such as the filesystem cache after suspending an encrypted device.
.Pp
Additional options include:
.Bl -tag -width ".Fl a"
.It Fl a
Suspend all
.Nm
devices.
.El
.It Cm resume
Resume previously suspended device.
The caller must ensure that executing this subcommand does not access the
suspended device, leading to a deadlock.
For example, suspending a device which contains the filesystem where the
.Nm
utility is stored is a bad idea.
.Pp
Additional options include:
.Bl -tag -width ".Fl j Ar passfile"
.It Fl j Ar passfile
Specifies a file which contains the passphrase component of the User Key,
or part of it.
For more information see the description of the
.Fl J
option for the
.Cm init
subcommand.
.It Fl k Ar keyfile
Specifies a file which contains the keyfile component of the User Key,
or part of it.
For more information see the description of the
.Fl K
option for the
.Cm init
subcommand.
.It Fl p
Do not use a passphrase as a component of the User Key.
Cannot be combined with the
.Fl j
option.
.El
.It Cm resize
Inform
.Nm
that the provider has been resized.
The old metadata block is relocated to the correct position at the end of the
provider and the provider size is updated.
.Pp
Additional options include:
.Bl -tag -width ".Fl s Ar oldsize"
.It Fl s Ar oldsize
The size of the provider before it was resized.
.El
.It Cm version
If no arguments are given, the
.Cm version
subcommand will print the version of
.Nm
userland utility as well as the version of the
.Nm ELI
GEOM class.
.Pp
If GEOM providers are specified, the
.Cm version
subcommand will print metadata version used by each of them.
.It Cm clear
Clear metadata from the given providers.
.Em WARNING :
This will erase with zeros the encrypted Master Key copies stored in the
metadata.
.It Cm dump
Dump metadata stored on the given providers.
.It Cm list
See
.Xr geom 8 .
.It Cm status
See
.Xr geom 8 .
.It Cm load
See
.Xr geom 8 .
.It Cm unload
See
.Xr geom 8 .
.El
.Pp
Additional options include:
.Bl -tag -width ".Fl v"
.It Fl v
Be more verbose.
.El
.Sh KEY SUMMARY
.Ss Master Key
Upon
.Cm init ,
the
.Nm
utility generates a random Master Key for the provider.
The Master Key never changes during the lifetime of the provider.
Each copy of the provider metadata, active or backed up to a file, can store
up to two, independently-encrypted copies of the Master Key.
.Ss User Key
Each stored copy of the Master Key is encrypted with a User Key, which
is generated by the
.Nm
utility from a passphrase and/or a keyfile.
The
.Nm
utility first reads all parts of the keyfile in the order specified on the
command line, then reads all parts of the stored passphrase in the order
specified on the command line.
If no passphrase parts are specified, the system prompts the user to enter
the passphrase.
The passphrase is optionally strengthened by PKCS#5v2.
The User Key is a digest computed over the concatenated keyfile and passphrase.
.Ss Data Key
During operation, one or more Data Keys are deterministically derived by
the kernel from the Master Key and cached in memory.
The number of Data Keys used by a given provider, and the way they are
derived, depend on the GELI version and whether the provider is configured to
use data authentication.
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 8
variables can be used to control the behavior of the
.Nm ELI
GEOM class.
The default value is shown next to each variable.
Some variables can also be set in
.Pa /boot/loader.conf .
.Bl -tag -width indent
.It Va kern.geom.eli.version
Version number of the
.Nm ELI
GEOM class.
.It Va kern.geom.eli.debug : No 0
Debug level of the
.Nm ELI
GEOM class.
This can be set to a number between 0 and 3 inclusive.
If set to 0, minimal debug information is printed.
If set to 3, the
maximum amount of debug information is printed.
.It Va kern.geom.eli.tries : No 3
Number of times a user is asked for the passphrase.
This is only used for providers which are attached on boot,
before the root filesystem is mounted.
If set to 0, attaching providers on boot will be disabled.
This variable should be set in
.Pa /boot/loader.conf .
.It Va kern.geom.eli.overwrites : No 5
Specifies how many times the Master Key is overwritten
with random values when it is destroyed.
After this operation it is filled with zeros.
.It Va kern.geom.eli.use_uma_bytes
.Nm
must allocate a buffer for every write operation, used when performing
encryption.
This sysctl reports the maximum size in bytes for which geli will perform the
allocation using
.Xr UMA 9 ,
as opposed to
.Xr malloc 9 .
.It Va kern.geom.eli.visible_passphrase : No 0
If set to 1, the passphrase entered on boot will be visible.
This alternative should be used with caution as the entered
passphrase can be logged and exposed via
.Xr dmesg 8 .
This variable should be set in
.Pa /boot/loader.conf .
.It Va kern.geom.eli.threads : No 0
Specifies how many kernel threads should be used for doing software
cryptography.
Its purpose is to increase performance on SMP systems.
If set to 0, a CPU-pinned thread will be started for every active CPU.
Note that this variable must be set prior to attaching
.Nm
to a disk.
.It Va kern.geom.eli.batch : No 0
When set to 1, can speed-up crypto operations by using batching.
Batching reduces the number of interrupts by responding to a group of
crypto requests with one interrupt.
The crypto card and the driver have to support this feature.
.It Va kern.geom.eli.key_cache_limit : No 8192
Specifies how many Data Keys to cache.
The default limit
(8192 keys) will allow caching of all keys for a 4TB provider with 512 byte
sectors and will take around 1MB of memory.
.It Va kern.geom.eli.key_cache_hits
Reports how many times we were looking up a Data Key and it was already in
cache.
This sysctl is not updated for providers that need fewer Data Keys than
the limit specified in
.Va kern.geom.eli.key_cache_limit .
.It Va kern.geom.eli.key_cache_misses
Reports how many times we were looking up a Data Key and it was not in cache.
This sysctl is not updated for providers that need fewer Data Keys than the limit
specified in
.Va kern.geom.eli.key_cache_limit .
.It Va kern.geom.eli.unmapped_io
Enable support for unmapped I/O buffers, currently implemented only on 64-bit
platforms.
This is an optimization which reduces the overhead of I/O processing.
This variable is intended for debugging purposes and must be set in
.Pa /boot/loader.conf .
.El
.Sh PERFORMANCE CONSIDERATIONS
The default value of
.Va kern.geom.eli.threads
is usually good for a system with one SSD.
However, it may need to be lowered on systems with many disks,
so as to avoid creating too much thread-switching overhead.
On systems with more disks than CPUs, it's best to set this variable
to 1.
.Pp
.Nm
internally uses
.Xr malloc 9
to allocate memory for operations larger than
.Va kern.geom.eli.use_uma_bytes ,
but malloc is slow for allocations larger than
.Va vm.kmem_zmax .
So it's best to avoid writing more than
.Ms MAX(kern.geom.eli.use_uma_bytes, vm.kmem_zmax)
in a single write operation.
On systems that format
.Xr zfs 4
on top of
.Nm ,
the maximum write size can be controlled by
.Va vfs.zfs.vdev.aggregation_limit
and
.Va vfs.zfs.vdev.aggregation_limit_non_rotating
for HDDs and SSDs, respectively.
.Sh EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.
.Sh EXAMPLES
Initialize a provider which is going to be encrypted with a
passphrase and random data from a file on the user's pen drive.
Use 4kB sector size.
Attach the provider, create a filesystem, and mount it.
Do the work.
Unmount the provider and detach it:
.Bd -literal -offset indent
# dd if=/dev/random of=/mnt/pendrive/da2.key bs=64 count=1
# geli init -s 4096 -K /mnt/pendrive/da2.key /dev/da2
Enter new passphrase:
Reenter new passphrase:
# geli attach -k /mnt/pendrive/da2.key /dev/da2
Enter passphrase:
# dd if=/dev/random of=/dev/da2.eli bs=1m
# newfs /dev/da2.eli
# mount /dev/da2.eli /mnt/secret
\&...
# umount /mnt/secret
# geli detach da2.eli
.Ed
.Pp
Create an encrypted provider, but use two User Keys:
one for your employee and one for you as the company's security officer
(so it is not a tragedy if the employee
.Qq accidentally
forgets his passphrase):
.Bd -literal -offset indent
# geli init /dev/da2
Enter new passphrase:	(enter security officer's passphrase)
Reenter new passphrase:
# geli setkey -n 1 /dev/da2
Enter passphrase:	(enter security officer's passphrase)
Enter new passphrase:	(let your employee enter his passphrase ...)
Reenter new passphrase:	(... twice)
.Ed
.Pp
You are the security officer in your company.
Create an encrypted provider for use by the user, but remember that users
forget their passphrases, so backup the Master Key with your own random key:
.Bd -literal -offset indent
# dd if=/dev/random of=/mnt/pendrive/keys/`hostname` bs=64 count=1
# geli init -P -K /mnt/pendrive/keys/`hostname` /dev/ada0s1e
# geli backup /dev/ada0s1e /mnt/pendrive/backups/`hostname`
(use key number 0, so the encrypted Master Key will be re-encrypted by this)
# geli setkey -n 0 -k /mnt/pendrive/keys/`hostname` /dev/ada0s1e
(allow the user to enter his passphrase)
Enter new passphrase:
Reenter new passphrase:
.Ed
.Pp
Encrypted swap partition setup:
.Bd -literal -offset indent
# dd if=/dev/random of=/dev/ada0s1b bs=1m
# geli onetime -d ada0s1b
# swapon /dev/ada0s1b.eli
.Ed
.Pp
The example below shows how to configure two providers which will be attached
on boot, before the root filesystem is mounted.
One of them is using passphrase and three keyfile parts and the other is
using only a keyfile in one part:
.Bd -literal -offset indent
# dd if=/dev/random of=/dev/da0 bs=1m
# dd if=/dev/random of=/boot/keys/da0.key0 bs=32k count=1
# dd if=/dev/random of=/boot/keys/da0.key1 bs=32k count=1
# dd if=/dev/random of=/boot/keys/da0.key2 bs=32k count=1
# geli init -b -K /boot/keys/da0.key0 -K /boot/keys/da0.key1 -K /boot/keys/da0.key2 da0
Enter new passphrase:
Reenter new passphrase:
# dd if=/dev/random of=/dev/da1s3a bs=1m
# dd if=/dev/random of=/boot/keys/da1s3a.key bs=128k count=1
# geli init -b -P -K /boot/keys/da1s3a.key da1s3a
.Ed
.Pp
The providers are initialized, now we have to add these lines to
.Pa /boot/loader.conf :
.Bd -literal -offset indent
geli_da0_keyfile0_load="YES"
geli_da0_keyfile0_type="da0:geli_keyfile0"
geli_da0_keyfile0_name="/boot/keys/da0.key0"
geli_da0_keyfile1_load="YES"
geli_da0_keyfile1_type="da0:geli_keyfile1"
geli_da0_keyfile1_name="/boot/keys/da0.key1"
geli_da0_keyfile2_load="YES"
geli_da0_keyfile2_type="da0:geli_keyfile2"
geli_da0_keyfile2_name="/boot/keys/da0.key2"

geli_da1s3a_keyfile0_load="YES"
geli_da1s3a_keyfile0_type="da1s3a:geli_keyfile0"
geli_da1s3a_keyfile0_name="/boot/keys/da1s3a.key"
.Ed
.Pp
If there is only one keyfile, the index might be omitted:
.Bd -literal -offset indent
geli_da1s3a_keyfile_load="YES"
geli_da1s3a_keyfile_type="da1s3a:geli_keyfile"
geli_da1s3a_keyfile_name="/boot/keys/da1s3a.key"
.Ed
.Pp
By convention, these loader variables are called
.Sm off
.Va geli_ No < Ar device No > Va _load .
.Sm on
However, the actual name prefix before
.Va _load , _type ,
or
.Va _name
does not matter.
At boot time, the
.Nm
module searches through all
.Sm off
.No < Va prefix No > Va _type No -like
.Sm on
variables that have a value of
.Sm off
.Dq < Ar device No > :geli_keyfile .
.Sm on
The paths to keyfiles are then extracted from
.Sm off
.No < Ar prefix No > Va _name
.Sm on
variables.
In the example above,
.Ar prefix
is
.Dq Li geli_da1s3a_keyfile .
.Pp
Not only configure encryption, but also data integrity verification using
.Nm HMAC/SHA256 .
.Bd -literal -offset indent
# geli init -a hmac/sha256 -s 4096 /dev/da0
Enter new passphrase:
Reenter new passphrase:
# geli attach /dev/da0
Enter passphrase:
# dd if=/dev/random of=/dev/da0.eli bs=1m
# newfs /dev/da0.eli
# mount /dev/da0.eli /mnt/secret
.Ed
.Pp
.Cm geli
writes the metadata backup by default to the
.Pa /var/backups/<prov>.eli
file.
If the metadata is lost in any way (e.g., by accidental overwrite), it can be restored.
Consider the following situation:
.Bd -literal -offset indent
# geli init /dev/da0
Enter new passphrase:
Reenter new passphrase:

Metadata backup can be found in /var/backups/da0.eli and
can be restored with the following command:

	# geli restore /var/backups/da0.eli /dev/da0

# geli clear /dev/da0
# geli attach /dev/da0
geli: Cannot read metadata from /dev/da0: Invalid argument.
# geli restore /var/backups/da0.eli /dev/da0
# geli attach /dev/da0
Enter passphrase:
.Ed
.Pp
If an encrypted filesystem is extended, it is necessary to relocate and
update the metadata:
.Bd -literal -offset indent
# gpart create -s GPT ada0
# gpart add -s 1g -t freebsd-ufs -i 1 ada0
# geli init -K keyfile -P ada0p1
# gpart resize -s 2g -i 1 ada0
# geli resize -s 1g ada0p1
# geli attach -k keyfile -p ada0p1
.Ed
.Pp
Initialize provider with the passphrase split into two files.
The provider can be attached using those two files or by entering
.Dq foobar
as the passphrase at the
.Nm
prompt:
.Bd -literal -offset indent
# echo foo > da0.pass0
# echo bar > da0.pass1
# geli init -J da0.pass0 -J da0.pass1 da0
# geli attach -j da0.pass0 -j da0.pass1 da0
# geli detach da0
# geli attach da0
Enter passphrase: foobar
.Ed
.Pp
Suspend all
.Nm
devices on a laptop, suspend the laptop, then resume devices one by one after
resuming the laptop:
.Bd -literal -offset indent
# geli suspend -a
# zzz
<resume your laptop>
# geli resume -p -k keyfile gpt/secret
# geli resume gpt/private
Enter passphrase:
.Ed
.Pp
To create a
.Nm
encrypted filesystem with a file as storage device follow this example.
First a file named private0 is created in
.Pa /usr
and attached as a memory disk like
.Pa /dev/md0
for example.
.Bd -literal -offset indent
# dd if=/dev/zero of=/usr/private0 bs=1m count=256
# chmod 0600 /usr/private0
# mdconfig -t vnode -f /usr/private0
.Ed
.Pp
It is recommended to place the following line in
.Xr rc.conf 5
to have the memory disk automatically created during boot.
.Bd -literal -offset indent
mdconfig_md0="-t vnode -f /usr/private0"
.Ed
.Pp
After
.Pa /dev/md0
is created a random key has to be generated and stored in a secure location,
like
.Pa /root
for example.
This key should be protected by a passphrase, which
is requested when geli init is called.
.Bd -literal -offset indent
# dd if=/dev/random of=/root/private0.key bs=64 count=1
# geli init -K /root/private0.key -s 4096 /dev/md0
Enter new passphrase:
Reenter new passphrase:
# geli attach -k /root/private0.key /dev/md0
Enter passphrase:
# dd if=/dev/random of=/dev/md0.eli bs=1m
.Ed
.Pp
Once the initialization of the
.Pa /dev/md0.eli
device is ready create a UFS filesystem and mount it for example in
.Pa /private .
.Bd -literal -offset indent
# newfs /dev/md0.eli
# mount /dev/md0.eli /private
.Ed
.Pp
After a system reboot the
.Nm
device can be mounted again with the following commands.
The call of geli attach will ask for the passphrase.
It is recommended to do this procedure after the boot, because otherwise
the boot process would be waiting for the passphrase input.
.Bd -literal -offset indent
# geli attach -k /root/private0.key /dev/md0
Enter passphrase:
# mount /dev/md0.eli /private
.Ed
.Sh ENCRYPTION MODES
.Nm
supports two encryption modes:
.Nm XTS ,
which was standardized as
.Nm IEEE P1619
and
.Nm CBC
with unpredictable IV.
The
.Nm CBC
mode used by
.Nm
is very similar to the mode
.Nm ESSIV .
.Sh DATA AUTHENTICATION
.Nm
can verify data integrity when an authentication algorithm is specified.
When data corruption/modification is detected,
.Nm
will not return any data, but instead will return an error
.Pq Er EINVAL .
The offset and size of the corrupted data will be printed on the console.
It is important to know against which attacks
.Nm
provides protection for your data.
If data is modified in-place or copied from one place on the disk
to another even without modification,
.Nm
should be able to detect such a change.
If an attacker can remember the encrypted data, he can overwrite any future
changes with the data he owns without it being noticed.
In other words
.Nm
will not protect your data against replay attacks.
.Pp
It is recommended to write to the whole provider before first use,
in order to make sure that all sectors and their corresponding
checksums are properly initialized into a consistent state.
One can safely ignore data authentication errors that occur immediately
after the first time a provider is attached and before it is
initialized in this way.
.Sh SEE ALSO
.Xr crypto 4 ,
.Xr geom 4 ,
.Xr loader.conf 5 ,
.Xr geom 8 ,
.Xr crypto 9
.Sh HISTORY
The
.Nm
utility appeared in
.Fx 6.0 .
Support for the
.Nm Camellia
block cipher was implemented by Yoshisato Yanagisawa in
.Fx 7.0 .
.Pp
Highest
.Nm GELI
metadata version supported by the given
.Fx
version:
.Bl -column -offset indent ".Sy FreeBSD" ".Sy version"
.It Sy FreeBSD Ta Sy GELI
.It Sy version Ta Sy version
.Pp
.It Li 6.0 Ta 0
.It Li 6.1 Ta 0
.It Li 6.2 Ta 3
.It Li 6.3 Ta 3
.It Li 6.4 Ta 3
.Pp
.It Li 7.0 Ta 3
.It Li 7.1 Ta 3
.It Li 7.2 Ta 3
.It Li 7.3 Ta 3
.It Li 7.4 Ta 3
.Pp
.It Li 8.0 Ta 3
.It Li 8.1 Ta 3
.It Li 8.2 Ta 5
.Pp
.It Li 9.0 Ta 6
.Pp
.It Li 10.0 Ta 7
.El
.Sh AUTHORS
.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org