GELI(8) BSD System Manager's Manual GELI(8)NAMEgeli — 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 follow‐
ing 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 hard‐
ware 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 verifica‐
tion) 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 - use‐
ful 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 (authenti‐
cation) 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 avail‐
able 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 recom‐
mended algorithm is HMAC/SHA256.
-b Ask for the passphrase on boot, before the
root partition is mounted. This makes it pos‐
sible 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 sup‐
ported 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 per‐
formance, 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 descrip‐
tion 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 (authentica‐
tion). For more information, see the descrip‐
tion of the init subcommand.
-e ealgo Encryption algorithm to use. For more informa‐
tion, see the description of the init subcom‐
mand.
-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 infor‐
mation, see the description of the attach sub‐
command.
-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 infor‐
mation, 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 subcom‐
mand, 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 compo‐
nent.
-P Do not use passphrase as the new key compo‐
nent.
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 dif‐
ferent 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 ker‐
nel 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 clos‐
ing all files and directories opened from a file system placed
on an encrypted device, unmounting the file system and detach‐
ing 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 mem‐
ory 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 descrip‐
tion 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 meta‐
data 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.
All variables can also be set in /boot/loader.conf.
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 informa‐
tion is printed. If set to 3, the maximum amount of debug infor‐
mation 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 soft‐
ware 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.
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 girlfriend
and one for you (so there will be no tragedy if she forgets her
passphrase):
# geli init /dev/da2
Enter new passphrase: (enter your passphrase)
Reenter new passphrase:
# geli setkey -n 1 /dev/da2
Enter passphrase: (enter your passphrase)
Enter new passphrase: (let your girlfriend enter her 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 key‐
file:
# 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 MODESgeli supports two encryption modes: XTS, which was standarized as IEE
P1619 and CBC with unpredictable IV. The CBC mode used by geli is very
similar to the mode ESSIV.
DATA AUTHENTICATIONgeli can verify data integrity when an authentication algorithm is speci‐
fied. 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 over‐
write any future changes with the data he owns without notice. In other
words geli will not protect your data against replay attacks.
SEE ALSOcrypto(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⟩
BSD October 20, 2010 BSD
