GELI(8)

NAME
geli - control utility for cryptographic GEOM class

SYNOPSIS
To compile GEOM_ELI into your kernel, place the following lines in your kernel configuration file:

device crypto
options GEOM_ELI

Alternately, to load the GEOM_ELI module at boot time, place the following line in your loader.conf(5):

    geom_eli_load="YES"

Usage of the geli(8) utility:

geli init [-bPv] [-a aalgo] [-B backupfile] [-e ealgo] [-i iterations] [-J newpassfile] [-K newkeyfile] [-l keylen] [-s sectorsize] prov
geli label - an alias for init
geli attach [-dprv] [-j passfile] [-k keyfile] prov
geli detach [-fl] prov ...
geli stop - an alias for detach
geli onetime [-d] [-a aalgo] [-e ealgo] [-l keylen] [-s sectorsize] prov
geli configure [-bB] prov ...
geli setkey [-pPv] [-i iterations] [-j passfile] [-J newpassfile] [-k keyfile] [-K newkeyfile] [-n keyno] prov
geli delkey [-afv] [-n keyno] prov
geli kill [-av] [prov ...]
geli backup [-v] prov file
geli restore [-fv] file prov
geli suspend [-v] -a | prov ...
geli resume [-pv] [-j passfile] [-k keyfile] prov
geli resize [-v] -s oldsize prov
geli clear [-v] prov ...
geli dump [-v] prov ...
geli list
geli status
geli load
geli unload

DESCRIPTION
The geli utility is used to configure encryption on GEOM providers.

The following is a list of the most important features:

•   Utilizes the crypto(9) framework, so when there is crypto hardware available, geli will make use of it automatically.
•   Supports many cryptographic algorithms (currently AES-XTS, AES-CBC, Blowfish-CBC, Camellia-CBC and 3DES-CBC).
•   Can optionally perform data authentication (integrity verification) utilizing one of the following algorithms: HMAC/MD5, HMAC/SHA1, HMAC/RIPEMD160, HMAC/SHA256, HMAC/SHA384 or HMAC/SHA512.
•   Can create a key from a couple of components (user entered passphrase, random bits from a file, etc.).
•   Allows to encrypt the root partition - the user will be asked for the passphrase before the root file system is mounted.
•   The passphrase of the user is strengthened with: B. Kaliski, PKCS #5: Password-Based Cryptography Specification, Version 2.0., RFC, 2898.
•   Allows to use two independent keys (e.g. "user key" and "company key").
•   It is fast - geli performs simple sector-to-sector encryption.
•   Allows to backup/restore Master Keys, so when a user has to quickly destroy his keys, it is possible to get the data back by restoring keys from the backup.
•   Providers can be configured to automatically detach on last close (so users do not have to remember to detach providers after unmounting the file systems).
•   Allows to attach a provider with a random, one-time key - useful for swap partitions and temporary file systems.
•   Allows to verify data integrity (data authentication).
•   Allows to suspend and resume encrypted devices.

The first argument to geli indicates an action to be performed:

init
    Initialize provider which needs to be encrypted. Here you can set up the cryptographic algorithm to use, key length, etc. The last provider's sector is used to store metadata. The init subcommand also automatically backups metadata in /var/backups/<prov>.eli file. The metadata can be recovered with the restore subcommand described below.

    Additional options include:

    -a aalgo
        Enable data integrity verification (authentication) using the given algorithm. This will reduce size of available storage and also reduce speed. For example, when using 4096 bytes sector and HMAC/SHA256 algorithm, 89% of the original provider storage will be available for use. Currently supported algorithms are: HMAC/MD5, HMAC/SHA1, HMAC/RIPEMD160, HMAC/SHA256, HMAC/SHA384 and HMAC/SHA512. If the option is not given, there will be no authentication, only encryption. The recommended algorithm is HMAC/SHA256.

    -b  Ask for the passphrase on 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 /boot/ directory, which can be a CD-ROM disc or USB pen-drive, that can be removed after boot.

    -B backupfile
        File name to use for metadata backup instead of the default /var/backups/<prov>.eli. To inhibit backups, you can use none as the backupfile.

    -e ealgo
        Encryption algorithm to use. Currently supported algorithms are: AES-XTS, AES-CBC, Blowfish-CBC, Camellia-CBC and 3DES-CBC. The default and recommended algorithm is AES-XTS.

    -i iterations
        Number of iterations to use with PKCS#5v2. If this option is not specified, geli 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.

    -J newpassfile
        Specifies a file which contains the passphrase or its part. If 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.

    -K newkeyfile
        Specifies a file which contains part of the key. If newkeyfile is given as -, standard input will be used. This argument can be specified multiple times.

    -l keylen
        Key length to use with the given cryptographic algorithm. If not given, the default key length for the given algorithm is used, which is: 128 for AES-XTS, AES-CBC, Blowfish-CBC and Camellia-CBC and 192 for 3DES-CBC.

    -P  Do not use passphrase as the key component.

    -s sectorsize
        Change decrypted provider's sector size. Increasing sector size allows to increase performance, because we need to generate an IV and do encrypt/decrypt for every single sector - less number of sectors means less work to do.

attach
    Attach the given provider. The master key will be decrypted using the given passphrase/keyfile and a new GEOM provider will be created using the given provider's name with an ".eli" suffix.

    Additional options include:

    -d  If specified, a decrypted provider will be detached automatically on last close. This can help with short memory - user does not have to remember to detach the provider after unmounting the file system. It only works when the provider was opened for writing, so it will not work if the file system on the provider is mounted read-only. Probably a better choice is the -l option for the detach subcommand.

    -j passfile
        Specifies a file which contains the passphrase or its part. For more information see the description of the -J option for the init subcommand.

    -k keyfile
        Specifies a file which contains part of the key. For more information see the description of the -K option for the init subcommand.

    -p  Do not use passphrase as the key component.

    -r  Attach read-only provider. It will not be opened for writing.

detach
    Detach the given providers, which means remove the devfs entry and clear the keys from memory.

    Additional options include:

    -f  Force detach - detach even if the provider is open.

    -l  Mark provider to detach on last close. If this option is specified, the provider will not be detached until it is open, but when it will be closed last time, it will be automatically detached (even if it was only opened for reading).

onetime
    Attach the given providers with random, one-time keys. The command can be used to encrypt swap partitions or temporary file systems.

    Additional options include:

    -a aalgo
        Enable data integrity verification (authentication). For more information, see the description of the init subcommand.

    -e ealgo
        Encryption algorithm to use. For more information, see the description of the init subcommand.

    -d  Detach on last close. Note, the option is not usable for temporary file systems as the provider will be detached after creating the file system on it. It still can (and should be) used for swap partitions. For more information, see the description of the attach subcommand.

    -l keylen
        Key length to use with the given cryptographic algorithm. For more information, see the description of the init subcommand.

    -s sectorsize
        Change decrypted provider's sector size. For more information, see the description of the init subcommand.

configure
    Change configuration of the given providers.

    Additional options include:

    -b  Set the BOOT flag on the given providers. For more information, see the description of the init subcommand.

    -B  Remove the BOOT flag from the given providers.

setkey
    Change or setup (if not yet initialized) selected key. There is one master key, which can be encrypted with two independent user keys. With the init subcommand, only key number 0 is initialized. The key can always be changed: 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 old passphrase/keyfile.

    Additional options include:

    -i 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 setkey subcommand, only one key have to be defined and this key has to be changed.

    -j passfile
        Specifies a file which contains the old passphrase or its part.

    -J newpassfile
        Specifies a file which contains the new passphrase or its part.

    -k keyfile
        Specifies a file which contains part of the old key.

    -K newkeyfile
        Specifies a file which contains part of the new key.

    -n keyno
        Specifies the number of the key 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 key decrypted with the passphrase/keyfile will be changed.

    -p  Do not use passphrase as the old key component.

    -P  Do not use passphrase as the new key component.

delkey
    Destroy (overwrite with random data) the selected key. If one is destroying keys for an attached provider, the provider will not be detached even if all keys will be destroyed. It can be even rescued with the setkey subcommand.

    Additional options include:

    -a  Destroy all keys (does not need -f option).

    -f  Force key destruction. This option is needed to destroy the last key.

    -n keyno
        Specifies the key number. 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.

kill
    This command should be used in emergency situations. It will destroy all keys on the 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 -r flag, the keys will not be destroyed, only the provider will be detached.

    Additional options include:

    -a  If specified, all currently attached providers will be killed.

backup
    Backup metadata from the given provider to the given file.

restore
    Restore metadata from the given file to the given provider.

    Additional options include:

    -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, geli will refuse to restore the data unless the -f switch is used. If the partition or slice has been grown, the resize subcommand should be used rather than attempting to relocate the metadata through backup and restore.

suspend
    Suspend device by waiting for all inflight request to finish, clearing all sensitive informations (like keys) from the kernel memory and blocking all further I/O requests until the resume subcommand is executed. This functionality is useful for eg. laptops - when one wants to suspend a laptop, one does not want to leave encrypted device attached. Instead of closing all files and directories opened from a file system placed on an encrypted device, unmounting the file system and detaching the device, the suspend subcommand can be used. Any access to the encrypted device will be blocked until the keys are recovered through resume subcommand, thus there is no need to close nor unmount anything. The suspend subcommand does not work with devices created with the onetime subcommand. Please note that sensitive data might still be present in memory after suspending encrypted device, because of file system cache, etc.

    Additional options include:

    -a  Suspend all geli devices.

resume
    Resume previously suspended device. The caller must ensure that executing this subcommand won't try to access suspended device, which will lead to a deadlock. For example suspending device, which contains file system where the geli utility is stored is bad idea.

    Additional options include:

    -j passfile
        Specifies a file which contains the passphrase or its part. For more information see the description of the -J option for the init subcommand.

    -k keyfile
        Specifies a file which contains part of the key. For more information see the description of the -K option for the init subcommand.

    -p  Do not use passphrase as the key component.

resize
    Inform geli 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.

    Additional options include:

    -s oldsize
        The size of the provider before it was resized.

clear
    Clear metadata from the given providers.

dump
    Dump metadata stored on the given providers.

list
    See geom(8).

status
    See geom(8).

load
    See geom(8).

unload
    See geom(8).

Additional options include:

-v  Be more verbose.

SYSCTL VARIABLES
The following sysctl(8) variables can be used to control the behavior of the ELI GEOM class. The default value is shown next to each variable. Some variables can also be set in /boot/loader.conf.

kern.geom.eli.version
    Version number of the ELI GEOM class.

kern.geom.eli.debug: 0
    Debug level of the 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.

kern.geom.eli.tries: 3
    Number of times a user is asked for the passphrase. This is only used for providers which should be attached on boot (before the root file system is mounted). If set to 0, attaching providers on boot will be disabled. This variable should be set in /boot/loader.conf.

kern.geom.eli.overwrites: 5
    Specifies how many times the Master-Key will be overwritten with random values when it is destroyed. After this operation it is filled with zeros.

kern.geom.eli.visible_passphrase: 0
    If set to 1, the passphrase entered on boot (before the root file system is mounted) will be visible. This possibility should be used with caution as the entered passphrase can be logged and exposed via dmesg(8). This variable should be set in /boot/loader.conf.

kern.geom.eli.threads: 0
    Specifies how many kernel threads should be used for doing software cryptography. Its purpose is to increase performance on SMP systems. If hardware acceleration is available, only one thread will be started. If set to 0, CPU-bound thread will be started for every active CPU.

kern.geom.eli.batch: 0
    When set to 1, can speed-up crypto operations by using batching. Batching allows to reduce number of interrupts by responding on a group of crypto requests with one interrupt. The crypto card and the driver has to support this feature.

kern.geom.eli.key_cache_limit: 8192
    Specifies how many encryption keys to cache. The default limit (8192 keys) will allow to cache all keys for 4TB provider with 512 bytes sectors and will take around 1MB of memory.

kern.geom.eli.key_cache_hits
    Reports how many times we were looking up a key and it was already in cache. This sysctl is not updated for providers that need less keys than the limit specified in kern.geom.eli.key_cache_limit.

kern.geom.eli.key_cache_misses
    Reports how many times we were looking up a key and it was not in cache. This sysctl is not updated for providers that need less keys than the limit specified in kern.geom.eli.key_cache_limit.

EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.

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 file system and mount it. Do the work. Unmount the provider and detach it:

    # 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

Create an encrypted provider, but use two keys: one for your employee and one for you as company's security officer (so there is no tragedy if the employee "accidentally" forgets his passphrase):

    # geli init /dev/da2
    Enter new passphrase:	(enter security officer passphrase)
    Reenter new passphrase:
    # geli setkey -n 1 /dev/da2
    Enter passphrase:	(enter security officer passphrase)
    Enter new passphrase:	(let your employee enter his passphrase ...)
    Reenter new passphrase:	(... twice)

You are the security-person in your company. Create an encrypted provider for use by the user, but remember that users forget their passphrases, so back Master Key up with your own random key:

    # dd if=/dev/random of=/mnt/pendrive/keys/`hostname` bs=64 count=1
    # geli init -P -K /mnt/pendrive/keys/`hostname` /dev/ad0s1e
    # geli backup /dev/ad0s1e /mnt/pendrive/backups/`hostname`
    (use key number 0, so the encrypted Master Key by you will be overwritten)
    # geli setkey -n 0 -k /mnt/pendrive/keys/`hostname` /dev/ad0s1e
    (allow the user to enter his passphrase)
    Enter new passphrase:
    Reenter new passphrase:

Encrypted swap partition setup:

    # dd if=/dev/random of=/dev/ad0s1b bs=1m
    # geli onetime -d -e 3des ad0s1b
    # swapon /dev/ad0s1b.eli

The example below shows how to configure two providers which will be attached on boot (before the root file system is mounted). One of them is using passphrase and three keyfiles and the other is using only a keyfile:

    # 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

The providers are initialized, now we have to add those lines to /boot/loader.conf:

    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"

Not only configure encryption, but also data integrity verification using HMAC/SHA256.

    # 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

geli backups metadata by default to the /var/backups/<prov>.eli file. If metadata is lost in any way (eg. by accidental overwrite), it can be restored. Consider the following situation:

    # 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:

If an encrypted filesystem is extended, it is necessary to relocate and update the metadata:

    # 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

Initialize provider with passphrase split into two files. The provider can be attached by giving those two files or by giving “foobar” passphrase on geli prompt:

    # 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

Suspend all geli devices, suspend a laptop, then resume devices one by one after resuming a laptop:

    # geli suspend -a
    # zzz
    <resume your laptop>
    # geli resume -p -k keyfile gpt/secret
    # geli resume gpt/private
    Enter passphrase:

ENCRYPTION MODES
geli supports two encryption modes: XTS, which was standardized as IEE P1619 and CBC with unpredictable IV. The CBC mode used by geli is very similar to the mode ESSIV.

DATA AUTHENTICATION
geli can verify data integrity when an authentication algorithm is specified. When data corruption/modification is detected, geli will not return any data, but instead will return an error (EINVAL). The offset and size of the corrupted data will be printed on the console. It is important to know against which attacks geli provides protection for your data. If data is modified in-place or copied from one place on the disk to another even without modification, geli 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 notice. In other words geli will not protect your data against replay attacks.

It is recommended to write the whole provider before the first use, in order to make sure that all sectors and their corresponding checksums are properly initialized into a consistent state.

SEE ALSO
crypto(4), gbde(4), geom(4), loader.conf(5), gbde(8), geom(8), crypto(9)

HISTORY
The geli utility appeared in FreeBSD 6.0. Support for Camellia block cipher is implemented by Yoshisato Yanagisawa in FreeBSD 7.0.

AUTHORS
Pawel Jakub Dawidek <pjd@FreeBSD.org>